KING'S College LONDON Top Library 201001026 1 KING'S COLLEGE LONDON Digitized by the Internet Archive in 2015 https://archive.org/details/b2130046x_0002 THE CYCLOPAEDIA OF ANATOMY and PHYSIOLOGY. VOL. II. LONDON : MARCHANT, PRINTER, I NG RAM-COURT- THE OF ANATOMY and PHYSIOLOGY. EDITED BY ROBERT B. TODD, M.D. F.R.S. FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS) PROFESSOR OF PHYSIOLOGY AND OF GENERAL AND MORBID ANATOMY IN KING'S COLLEGE, LONDON, ETC. ETC. I) I A I N 8. LONDON: SHERWOOD, GILBERT, AND PIPER, PATERNOSTER- ROW. 1839. CONTRIBUTORS. ROBERT ADAMS, Esq. Surgeon to the Richmond Hospital, and Lecturer on Anatomy and Surgery, Duhlin. B. ALCOCK, M.B. Dublin. W. P. ALISON, M.D. F.R.S.E. Professor of the Institutes of Medicine in the Univer- sity of Edinburgh, &c. JOHN ANDERSON, Esq. M.E.S. Richmond. J. APJOHN, M.D. M.R.I.A. Prof, of Chem. to the Royal Coll.'of Surgeons, Ireland. VICTOR AUDOUIN, M.D. Paris. Profcsseur-Administrateurau Musecd'Histoire Naturelle. B. G. BABINGTON, M.D. F.R.S. THOMAS BELL, F.R.S. Professor of Zoology in King's College, London. CHARLES BENSON, M.D. M.R.I.A. Prof, of Med. to the Royal Col. of Surgeons, Ireland. JOHN BOSTOCK, M.D. V.P.R.S. London. W. BOWMAN, Esq. Demonstrator of Anatomy, King's College, London. W. T. BRANDE, F.R.S. Professor of Chemistry to the Royal Institution, &c. J. E. BRENAN, M.D. G.BRESCHET, M.D. Surgeon to the Hotel-Dieu, Paris. W. B. CARPENTER, Esq. Lect. on Forensic Med. at the Bristol Med. Sch., &c. JOHN COLDSTREAM, M.D. Leith. Member of the Wernerian Natural History Society of Edinburgh, &c. &c. DAVID CRAIGIE, M.D. F.R.S.E. Fellow of the RoyalCollege of Physicians,Edinburgh,&c. T. BLIZARD CURLING, Esq. Assistant Surgeon to the London Hospital, and Lec- turer on Morbid Anatomv. G. P. DESHAYES, M.D. Paris. A. T. S. DODD, Esq. Surgeon to the Infirmary, Chichester, and late Demon- strator of Anatomy at Guy's Hospital. H. DUTROCHET, M.D. Member of the Institute of France, Paris. W.F.EDWARDS, M.D. F.R.S. Member of the Institute of France, Paris. H. MILNE EDWARDS, M.D. Professor of Natural History to the College of Henry IV., and to the Central School of Arts and Manu- factures, Paris. ARTHUR FARRE, M.B. F.R.S. Physician to the Gen. Disp., and Lect. on Forensic Med. and Comp. Anat. and Physiol, at St. Bartholo- mew's Hospital. R. D. GRAINGER, Esq. Lecturer on Anatomy and Physiology at the Webb- Street School of Anatomy. R. E. GRANT, M.D. F.R.S. L. & E. Fellow of the Royal College of Physicians, Edinburgh, and Professor of Comparative Anatomy and Zoology in University College, &c. &c. MARSHALL HALL, M.D. F.R.S. L. & E. London. HENRY HANCOCK, Esq. Lect. on Anat. and Physiology at, and Surgeon to the Charing-Crnss Hospital. ROBERT HARRISON, M.D. M.R.I.A. Prof, of Anat. and Surg, in the Univ. of Dublin. JOHN HART, M.D. M.RJ.A. Prof, of Anat. in the Royal Coll. of Sur. Dublin. ISID. GEOFFROY ST. H1LAIRE, M.D. Member of the Institute of France, Paris. ARTHUR JACOB, M.D. M.R.I.A. Professor of Anatomy and Physiology to the Royal College of Surgeons in Ireland. T. RYMER JONES, Esq. Prof, of Comp. Anat., in King's College, London. T. WHARTON JONES, Esq. London. F. KIERNAN, F.R.S. London. T. WILKINSON KING, Esq. Lect. on Comp. Anat. and Physiol, at Guy's Hospital. SAMUEL LANE, Esq. Lecturer on Anatomy, St. George's Hospital, London. F. T. MACDOUGALL, Esq. JOHN MALYN, Esq. Surgeon to the Western Dispensary. W. F. MONTGOMERY, M.D. M.R.I.A. Fellow and Professor of Midwifery to the King and Queen's College of Physicians in Ireland. GEORGE NEWPORT, Esq. Vice-Pres. of the Entomological Society of London. R. OWEN, F.R.S. F.G.S. Professor of Comparative Anatomy and Physiology to the Royal College of Surgeons in London. RICHARD PARTRIDGE, F.R.S. Prof, of Descriptive and Surgical Anat. in King's Coll. London. BENJAMIN PHILLIPS, F.R.S. London. Surgeon to the Marylebone Infirmary. W. H. PORTER, Esq. Prof, of Surgery to the Royal Coll. of Surg, in Ireland. J. C. PRICHARD, M.D. F.R.S. Corresponding Member of the Institute of France, Member of the Royal Academy of Medicine of Palis, and Senior Physician to the Bristol Infirmary. G. O. REES, M.D. London. J. REID, M.D. Edinburgh. Fellow of the Royal College of Physicians in Edin- burgh, and Lecturer on the Institutes of Medicine. EDWARD R1GBY, M.D. F.L.S. Lect. on Midwifery at St. Bartholomew's Hospital. J. FORBES ROYLE, M.D. V.P.R.S. F.G.S. Professor of Materia Medicain King's College, London. HENRY SEARLE, Esq. London. E. R. A. SERRES, M.D. Physician to the Hospital of La Pitie, &c. &.C. Paris. W. SHARPEY, M.D. F.R.S.E. Prof, of Anat. and Physiol, in Univ. Col. London. JOHN SIMON, Esq. Demonstrator of Anatomy in King's College, London. J. Y. SIMPSON, M.D. Fellow of the Royal College of Physicians, Edinburgh, and Lecturer on Midwifery. SAMUEL SOLLY, F.R.S. GABRIEL STOKES, M.D. Surgeon to the South Eastern Dispensary, and Demon- strator of Anatomy in the Park-street School of Medi- cine, Dublin. J. A. SYMONDS, M.D. Physician to the Bristol General Hospital and Dispen- sary, and Lecturer on the Theory and Practice of Medi- cine at the Bristol Medical School. ALLEN THOMSON, M.D. Fellow of the Royal College of Surgeons, andLccturer on the Institutions of Medicine, Edinburgh. RUDOLPH WAGNER, M.D. Professor of Medicine and of Comparative Anatomy in the Royal University, Eiiangen. C. WIIEATSTONE, F.R.S. Professor of Natural Philosophy in King's College, London. REV. G.WILLIS, F.R.S. F.G.S. Cambridge. R. WILLIS, M.D. Physician to the Royal Infirmary for Children, and Lecturer on the Theory and Practice of Medicine in the Aldersgate-street School. W. J.ERASMUS WILSON, Esq. Leclureron Anat .and Physiol, in Sydenham Coll Lon.; and Consulting Surgeon to the St. Pancras Infirmary. W. YARRELL, F.L.S. F.Z.S. CONTENTS OF THE SECOND VOLUME. Diaphragm Dr. Benson Digestion Dr. linstock Digestive Canal Dr. Grant Echinodermata Dr. Sharpey Edentata T. Bell, Esq Elasticity Dr.Brcnan Elbow, Region of the Dr. Hart . . Elbow, Joint of, } Page 1 6 27 . 30 4G 55 62 Normal Anatomy Dr. Hart » 05 Elbow, Joint of, Ab- \ j R. Adams, Esq. . . 07 normal Anatomy . Electricity, Animal .. Dr. Coldstream . . Endosmosis Dr. Dutrochet .... Entozoa R. Owen, Esq Erectile Tissue ...... Dr. Hart Excretion Dr. Alison Extremity Dr. Todd Eye Dr. Jacob Face R. Partridge, Esq. Fascia Dr. Todd Fat W.T. Brande,Esq. Femoral Artery Dr. Alcock Fibrine W.T. Brande, Esq. Fibro-Cartilage Dr. Todd Fibrous Tissue R.D.Grainger, Esq. Fibular Artery Dr. Todd Fifth Pair of Nerves. . Dr. Alcock Foetus Dr. Montgomery. Foot, Bones and Joints of Fool, Abnormal Con- i ' , cA.T. S. Dodd,Esq. ditions of } Foot, Regions and i „. . „ \A.T.S.Dodd,Esq. Muscles of 5 ' 1 Todd 81 98 111 144 117 154 171 207 229 231 235 257 260 203 267 268 316 338 347 350 } .S'. Solly, Esq 361 Fore-arm, Muscles and Regions of . Fourth Pair of Nerves Dr. Alcock Ganglion R.D.Grainger, Esq. Gasteropoda T. Rymer Jones, Esq. 370 371 377 Gelatin W.T. Brande, Esq. Generation. Organs > „ „ „ _, ' h \T. Rymer Jones, Esq. of ' Generation Dr. Allen Thomson.. Gland R.D. Grainger, Esq. Glosso pharyngeal ~> _ _ . , J Dr. Real Nerve * Glutasal Region A T. S. Dodd, Esq. Groin, Region of the Dr. Todd Haamatosiue Dr. Rees Hand, Bones of the Dr. Todd Hand, Abnormal > } R. Adams, Esq Conditions of the ' Hand, Muscles of > _ _ ,,,, _ ,,' ' ^F.T. M'Dougall, Esq. Hand, Regions of the F. T. M'Dougall, Esq. Hearing, Organ of. . T. W. Jones, Esq. . . Hearing Dr. Todd Heart Dr. Reid Heart, on the -v Arrangement of >H. Searle, Esq the Fibres of the s Page 41)4 400 424 480 194 500 503 503 505 510 519 523 529 564 577 619 Heart, Abnormal 1 „ ',. . „ , \Dr. Todd Conditions of the ' Heat, Animal Dr. W.F.Edwards . Hermaphroditism .. Dr. Simpson Hernia W. II. Porter, Esq. Hibernation Dr. Marshall Hall . . Hip-Joint, Normal > TT . i II. Hancock, Esq. . . Anatomy ' Hip-Joint, Abnor- ) r. . , „ v k. Adams, Esq. malConditions of Hyperemia Dr. Todd Hypertrophy Dr. Todd Iliac Arteries Dr. Alcock , Innominata Artery . H. Hancock, Esq. . . Insecta G. Newport, Esq. . Insectivora T. Bell, Esq 630 648 684 738 764 770 780 825 826 827 850 853 994 THE CYCLOPAEDIA ANATOMY AND PHYSIOLOGY. DIAPHRAGM (in anatomy), (Jia^ay^a, inter, and (p^curo-a, sepio, claudo ; Lat. dia- phragm a ; Ital. diaf'ramma; Fr. diaphragms; Ger. Zwerchfell ; Eng. midriff), the name given to that musculo-tendinous septum by which the cavities of the thorax and abdomen are separated from each other in the Mammalia. Nothing analogous to the diaphragm of mam- mals can be detected in the Invertebrate classes of animals ; the function of which it is a princi- pal muscularagentin the Mammalia, respiration, being effected by the skin, intestines, stigmata, trachea1, gills, &c. Most of the Vertebrata, however, exhibit something analogous to the diaphragm. Thus in Fishes the muscular sep- tum dividing the cavity of the branchial ap- paratus (thorax) from the abdomen bears a certain resemblance to the diaphragm. Birds have muscles which proceed obliquely upwards in the form of flat bundles of fibres from the middle of the lower ribs to the under part of the lungs, where they are lost in the pleura covering these organs ; and thus by their con- traction depress the lungs themselves, expand their cells, and facilitate the ingress of air into them. These muscular fibres are particu- larly developed in the parrot.* But, as has been said, it is only in Mammalia that the genuine diaphragm is to be found ; and all the animals of this class possess it. The organ, as might be expected, undergoes some modifica- tions in different families. In amphibious and cetaceous mammalia it approximates to that of birds. A very strong and fleshy diaphragm is * C. G. Carus, Comparative Anatomy. VOL. II. attached to the dorsal side of the cavity of the trunk so low down that it ascends considerably in order to be connected in a peculiar manner with the upper and anterior extremity of the abdominal muscles ; so that the lungs lie be- hind rather than above the diaphragm.'* In the porpoise there is no central tendon.f The horse, elephant, rhinoceros, and other animals whose ribs approach the pelvis, have a very- extensive diaphragm, which forms an elevated arch towards the thorax.} This shape is neces- sary to accommodate the bulky contents of the abdomen, without altering the attachments of the muscle, which, as in man, are connected to the lowest ribs. Some other variations from the structure and form of the diaphragm in man might be noticed, but they are very unim- portant. We shall therefore proceed to give a detailed account of the muscle in the human subject. Diaphragm (human anatomy). — The dia- phragm in man is a muscle of great importance (post cor facile princeps, Haller), being the chief agent by which respiration is carried on, while it assists in the performance of many other im- portant processes. It is placed between the thorax and abdomen, forming a convex floor to the former, and a concave ceiling to the latter. Although a single muscle, and situated in the median line, it is not symmetrical ; the right side of it is more extensive than the left. Symmetry, however, was not necessary in an * C. G. Cams, Comparative Anatomy, t Tyson. % Cuvier, Anat. Comp. vol. iv. B 2 DIAPHRAGM. organ which could exert no influence on the external form ; nor was it to be expected in a muscle which is not wholly voluntary. In this article it is intended to describe, 1st, the form, structure, and organization of the diaphragm ; 2nd, its uses ; and, 3rd, its malformations and diseases. Fig. I. Thoracic surface seen from behind, the vertebrae being removed. For the convenience of description the dia- phragm is usually divided into two portions — the upper, which is called the costal, or true or greater muscle ; and the lower, which is named the vertebral, or smaller, and is also well known as the crura or pillars. This division is sanc- tioned by the situation, the shape, and the uses of the two portions. The upper portion, placed tranversely, (sep- tum transversum,) is thin, but of great super- ficial extent, being connected by its margins to the entire circumference of the inferior outlet of the thorax. Narrow between the sternum and spine, it spreads out on each side into large wings, and its outline bears some resemblance to the figure of eight laid on the side, thus od . The centre is tendinous ; the border consists of fleshy fibres. The tendinous part (Jig. 1, T) {centrum tendineum, s. nerveum, s. phrenicum, cordifbrm tendon) is of considerable size, and in shape resembles the trefoil leaf. It presents a large semicircular notch behind towards the spine, and is deeply divided on its anterior margin into three lobes, of which one points for- wards and one to each side. Of these lobes the right is usually the largest, the left the smallest; the anterior is the shortest, and sometimes the broadest; the left is the narrowest and often the longest. But these proportions will be found to vary in different individuals. The tendon is composed of fibres which pursue various courses. The greater number radiate from the vertebral notch ; these are crossed by others which run in every direction, and which seem to be continuous with the muscular fibres ; and others again appear to be laid on the tendon as accessaries, rather than as con- tributing to its texture. These last are most distinctly seen in old men, and on the under surface of the right lobe. The tendinous centre forms nearly the highest part of the arch. It is less curved than the fleshy portion, and more fixed in its position. One large opening pre- sents itself here, between the right and middle lobes, through which the vena cava passes to the heart. From the anterior and lateral margins of this tendon the muscular fibres pass off in arches, to be inserted into all the base of the thorax by digitations which mix with those of the trans- versus abdominis. Beginning in front, we find two slender fasci- culi running downwards and forwards to the ensiform cartilage. These are separated from each other by a line of cellular tissue, marking the median line of the muscle; sometimes one or both of these bundles may be absent, pro- bably resulting from an arrest of formation. To the outside of these, on each side, a con- siderable triangular interval exists, where the pleura and peritoneum are separated only by cellular substance. Here some small branches of the internal mammary artery pass to the ab- domen ; and in this situation fluids might easily find their way from the cellular tissue of one cavity to that of the other. The fibres next in order, bounding these spaces externally, are much longer ; they pass outwards and down- wards to the seventh rib, and are inserted by a DIAPHRAGM. A, broad digitation into the point of the bone and into about one half of the adjoining portion of its cartilage. The next fibres are still longer, usually the longest of all; they run outwards, then downwards, forming the second digitation, which is attached in a similar manner to the eighth rib. The following fibres becoming shorter as they approach the spinal notch, go to the ninth and tenth ribs, and are similarly con- nected. The succeeding ones, still shorter, proceed to the eleventh and twelfth, and attach themselves to a considerable portion of their length. In the two lowest intercostal spaces the diaphragm and transversus abdominis are united by a common aponeurosis, which is very thin ; and here it is not very unusual to meet with a deficiency in the diaphragm. The thin portion of the muscle, near to the crura, has its short fleshy fibres inserted into the ligamentum arcuatum externum.* (JVg. 1, d.) This last appel- lation is bestowed on a thin aponeurosis which stretches from the inferior margin of the last rib to the point of the transverse process of the first lumbar vertebra. In reality it is nothing more than the anterior layer of the tendon of the transversus abdominis which lies in front of the quadratus lumborum muscle, and is connected to the lowest rib. By pulling the rib outwards the aponeurosis is projected into a fold which looks like a ligament. It is designated ex- ternum to distinguish it from another that is much stronger and more truly ligamentous, which arches over the psoas magnus muscle, is attached to the transverse process of the first lumbar vertebra (just where the former ends), and to the body of the second. The latter is known as the ligamentum arcuatum internum f (fig. it is also called the true, and the external the false, — names derived from their structure. The vertebral or smaller muscle of the dia- phragm is placed almost perpendicularly. The fibres pass off from the concave margin of the tendon which is turned to the spine. They run downwards and a little backwards at first, then along the lumbar vertebra, into which they are principally inserted. The shortest and most external of them go to the internal ligamentum arcuatum ; but the greater number form two large and long fasciculi, the crura, or pillars, or appendices of the diaphragm. The right crus is longer and thicker than the left, and is nearer to the middle line. It is attached by tendinous slips to the bodies of the three (often of the four) superior lumbar ver- tebrae and to the intervertebral substances. The left is attached in a similar way, but never de- scends so low. Both become smaller as they pass down, the more external fibres being soonest inserted. The muscular bundles, on quitting the cordiform tendon, separate imme- diately from each other, to permit the oesopha- gus to pass into the abdomen, and unite again behind that tube. Here a crossing or inter- lacing of the fibres takes place, a considerable bundle descending from the left side of the * Arcus tendinous exterior, Scnac. t Arcus tendineus interior, Id. oesophagus to the right crus, and a smaller one from the right side to the left crus. In general the latter is placed anteriorly ; and occasionally two bundles descend from each side alternating with their opposites. The fleshy fibres again separate on a level with the lower edge of the last dorsal vertebra to allow the aorta to pass, and they continue afterwards distinct. The foramina or openings which present themselves in this septum require to be noticed. Three large ones have been already mentioned ; but as the organs which they transmit are of great importance, they deserve more minute at- tention. The first is situated in the tendon of the diaphragm, toward its posterior part, a little to the right of the centre (Jig A, c). It corre- sponds to the line of division between the middle and right lobes. Its shape is quadrangular, (foramen quadratum,) having an anterior, a pos- terior, a right and a left edge. The right is the longest, the anterior the shortest, and these two often appear to form but one. The inferior vena cava passes through this opening and im- mediately empties itself into the right auricle of the heart. The vein is firmly connected to the foramen by means of thin aponeuroses sent off from the tendinous margins; the posterior margin sending fibres upwards, the lateral downwards, and the anterior in both directions. This is the highest opening in the diaphragm, being on a level with the lower edge of the ninth dorsal vertebra and fifth rib. As the boundaries of it are entirely tendinous they cannot act on the vein themselves, and the ac- tion of the muscular fibres only serves to keep it dilated. Some branches of the phrenic nerve accompany this vein. A little to the left of the median line, and close behind the central tendon, we find an opening of an elliptical form through which the oesophagus and pneumogastric nerves pass (fig. i,e). Its major axis, two inches in length, is di- rected obliquely downwardsand backwards. The borders are entirely muscular, at least very ge- nerally, for it sometimes happens that the ante- rior extremity is bounded by the cordiform ten- don. It results from a separation of the fibres which are descending to constitute the crura, and may be said to lie between the crura. The crossing or interlacing of the fibres which takes place just behind it must enable them to shut up this opening completely when they act strongly. This foramen is on a level with the tenth dorsal vertebra, its upper and lower an- gles corresponding to the planes of the upper and lower surfaces of that bone. About two inches below the inferior point of the oesophageal opening the aorta may be seen, coming out of the thorax, opposite the lower edge of the last dorsal vertebra (fig. 1, a.) This great vessel enters the abdomen by a canal which is formed posteriorly by bone, anteriorly by the decussating fibres, and on either side by the crura of the diaphragm. These crura, after passing along the sides of the artery, almost meet behind it by their tendinous expansions lower down. The margin of the aortic opening is bordered with tendon, and the fleshy fibres are so connected with it that their action does B 2 4 DIAPHRAGM. not at all diminish the size of the passage Along with the aorta and to its right side we see the vena azygos and thoracic duct passing into the thorax. Some other foramina transmit vessels and nerves, but they are very small and irregular. The sympathetic nerve usually passes with the psoas muscle under the internal ligamentum arcuatum. The right splanchnic slips out of the thorax between the fibres of the right eras, at a point internal, superior, and anterior to the sympathetic. The left splanchnic comes in the same way, or more frequently with the aorta. The lesser splanchnic passes at the outer side of the former, separated from it by a few fibres. Behind the external ligamentum arcuatum the last dorsal nerve may be seen. Filaments of the phrenic nerve pierce the muscle in several places, principally its tendinous part, and some pass through the opening for the vena cava. And branches of the internal mammary artery creep through those cellular' spaces which are left between the xiphoid cartilage and first costal attachment. The upper muscle of the diaphragm is lined for the most part of its under surface by the peritoneum, and on its upper by the pleurae and pericardium ; being thus placed between serous membranes. In some points the peri- toneum is reflected off to form ligaments for the liver, and there this last organ comes in contact with the muscle. The same thing oc- curs to a small extent in the case of the kid- neys. The upper surface too is for a little way all along its margin destitute of serous covering, and in contact with the ribs, intercostal mus- cles, quadratus lumborum, psoas, and triangu- laris sterni. Over the serous membranes on the thoracic surface we find on each side the base of the lungs, and in the centre the heart resting on the middle lobe of the tendon and on some muscular fibres to its right. The ab- dominal surface is related to the liver, stomach, spleen, and kidneys. The inferior muscle of the diaphragm has one surface turned back to the spinal column, and in contact with it and with a little of the aorta; the other surface looks forwards, and is covered by the suprarenal capsules, the semi- lunar ganglia, and various nerves, the aorta and its principal branches, the ascending cava, the commencement of the abdominal vena porta and its tributaries, the pancreas, stomach, duo- denum, and occasionally other parts. Little or no peritoneum can touch this portion. Arteries. — A muscle of so much importance in the animal economy as the diaphragm, and so perpetually in action, requires a large supply of blood. This it receives through numerous channels and from distinct sources ; and as all its vessels inosculate freely in its substance, no failure in the supply can well occur. The phrenic and internal mammary are distributed to its middle ; the same vessels, with the in- tercostal, the lumbal, and some small aortic twigs, feed the circumference. Veins. — The veins of the diaphragm accom- pany the arteries as in other parts of the body ; each artery having one or two vena; comites. The principal veins, however, correspond to the phrenic artery, and pour their blood into two trunks, a right and a left, which empty them- selves into the cava. They are usually seen on the under surface of the tendon, sometimes on the upper; or there may be two above and two below. Occasionally they lie between the two surfaces, so that their entrance into the cava is not seen ; and in some cases they join the hepatic veins. Lymphatics. — The diaphragm is furnished with lymphatic vessels as other muscles, but there is nothing peculiar in them. They are not easily demonstrated, as they do not form any very distinct trunks, but join with the lymphatics of the neighbouring organs. Nerves. — The diaphragm receives a great number of nerves. The lumbar send twigs to the crura, the lower dorsal to the broad muscle, and there is a phrenic plexus sent off from the solar, which accompanies the phrenic arteries, and distributes its numerous and delicate fila- ments with extreme minuteness to the under surface of the muscle. From the plexus which the eighth pair forms on the stomach, we trace also some fine filaments. But the chief and most important nerves are the phrenic. The phrenic nerve arises from the cervical plexus ; its principal origin is from the fourth cervical nerve, to which there is usually joined a small twig from the third. It runs down along the anterior scalenus, and gets into the thorax be- tween the subclavian artery and vein. In the neck it generally receives filaments from each cervical nerve. As it enters the thorax, it com- municates with the inferior cervical ganglion, and gets a filament from the descendens noni and the pneumogastric. The nerve thus formed is conducted by the mediastinum and pericar- dium, in front of the root of the lung, to the diaphragm; the left being a little longer than the right, and thrown somewhat further back by the position of the heart. It enters the diaphragm at the anterior edge of the tendon in six or seven branches, the largest of which pass backwards. Some go through the muscle, ramify on its under sur- face, and anastomose with the solar plexus ; and one may usually be traced through the opening for the cava on to that plexus. The influence which these nerves exert on die organ will presently be adverted to. Uses. — The chief use of the diaphragm is to assist in the function of respiration, and it will be found to be the principal agent in the me- chanical part of that process. By its action the thoracic cavity is enlarged from above downwards, whilst its circumference is in- creased by the intercostal and other muscles. When the diaphragm acts, the entire muscle descends, pushing the abdominal viscera down- wards and forwards ; but its different portions descend very unequally. The tendinous centre is nearly fixed, and the crura are incapable of much change of position ; it is only in the broad lateral expansions that the motion is very apparent. The muscular fibres of these when relaxed are pressed upwards, and present arches, convex to the thorax, and rising even above the tendon ; but when brought into ac- tion, each fibre approaches to a right line, which runs obliquely down from the tendon to its point of insertion. Thus, instead of a great arch we have a number of inclined planes, very short in front, very long at the sides, and of intermediate length further back, all surmount- ed by a tendinous platform. The base of the lung resting on the muscle descends with it ; the liver, stomach, spleen, and all the moveable viscera of the abdomen are pressed downwards and forwards against the abdominal muscles. When the diaphragm descends, therefore, in- spiration takes place by the rush of air into the expanding thorax ; when it ascends expiration is the result, the air being forced out. In the former case the diaphragm is active ; in the latter it is completely passive, following the re- siliency of the lungs, and pressed up by the action of the abdominal muscles on the viscera beneath.* The central tendon descends very little on account of its attachment to the peri- cardium : descent here would be useless or worse; but the lateral portions on which the broad bases of the lungs rest, freely change their place, and allow of considerable expansion of the thorax where it is most required. From viewing the insertion of the diaphragm into the lower ribs it might be thought that they would be drawn in by its action, and the capacity of the thorax thereby diminished more than increased; but the intercostals prevent this occurrence by acting at the same moment to elevate and draw out the ribs. The crura, besides acting in common with the broad muscle in enlarging the thorax, serve to fix the central tendon, and prevent it from being drawn to either side by the irregular ac- tion of either half of the muscle, or forced too high up. They may also by their fibres conti- nued on each side of the oesophageal orifice, and contracting in concert with the rest of the muscle, close that opening, and thus prevent regurgitation from the stomach at the time when this viscus is pressed upon by the descent of the diaphragm. The extent to which the diaphragm descends is not great. The central tendon will not admit of much displacement in the normal state of the parts, and the shape and motions of the liver show that even the great ate do not un- dergo much alteration. Haller indeed says that he saw the diaphragm descend so much in violent inspiration as to present a convexity to- wards the abdomen. f But this is quite incre- dible. The utmost muscular effort, if there were no fixed point in its centre, could only obliterate the arch; but even this we think im- possible on account of its attachments. We find on some occasions one side of the dia- phragm act independently of the other. The importance of the diaphragm in respira- tion is shewn by the difficulty with which that ,,r * Senac says the anterior fibres assist in expira- tion by drawing the ribs inwards and backwards. Acad, des Sciences, 1729. t In violentissima respiratione omnino vidi deor- sum versus abdomen diaphragma convexum reddi. Haller, Elcm. I'hys. lib. viii. sect. 1. IAGM. 5 function is performed when the actions of the muscle are interfered with. Ascites and tu- mours in the abdomen render the breathing shorter; even a full meal will have this effect, owing to the impediments to the descent of the diaphragm. If the phrenic nerves be divided in a living animal, great difficulty of breathing- follows, the entire labour of respiration being thrown on the muscles which elevate the ribs. If the spinal marrow be divided above the, giving off of the phrenic nerves, respiration ceases at once, but not so if divided imme- diately below that point ; and in a case of fatal dyspnoea Beclard could find no cause but a tumour on one of the phrenic nerves. Besides the part which it plays in respira- tion, it is probable that the diaphragm, by its ordinary motions, exerts a beneficial influence on the digestive organs. The liver must be more or less affected by it in its secretion, and the gall-bladder is supposed to receive from it a compression which in some degree makes amends for the want of muscular fibres,* whilst the agitation of the hollow viscera will favour the transmission of their contents. The chyle in the lacteals and thoracic duct may also receive an impulse from the dia- phragm. Some anatomists were of opinion that the venous circulation in the abdomen was also assisted by the pressure, but the absence of valves in these vessels must prevent them from deriving any assistance from alternate compres- sion and relaxation. It acts powerfully, how- ever, on the venous circulation of the whole system by the vacuum which it has a tendency to form in the thorax. The nerves which pass through the dia- phragm, as the par vagum, sympathetics, and splanchnics, were formerly supposed to suffer compression, and the alternate transmission and interruption of the nervous influence, it was thought, could account for the pulsations of the heart and the vermicular motions of the intestines. But all this is too obviously erro- neous to require comment. The diaphragm assists, though rather as a passive instrument, in the expulsion of the urine, feces, &c. For this purpose the thorax is filled with air, the rima glottidis is closed, and the diaphragm forms a resisting surface against which the abdominal muscles press the hollow viscera, and force out their contents wherever an exit is afforded them. The diaphragm is more or less engaged in hiccup, yawning, sighing, sobbing, groaning, which are all actions connected in various ways with the function of respiration, and some of them more especially dependent on the dia- phragm, particularly hiccup, which is an explo- sive inspiration, in which the diaphragm acts involuntarily by a short and sudden effort, a sound being at the same time produced in the larynx. The diaphragm also performs an important part in vomiting. A full inspiration precedes this act, then the glottis is closed, and the ab- * Senac. 6 DIGESTION. dominal muscles forcibly press the stomach against the diaphragm, so as to assist the anti- peristaltic motion of that viscus. Magendie made experiments to show that unless the dia- phragm or abdominal muscles acted on the stomach, no vomiting could take place. He went too far, however, when he attributed the entire result to them. Substituting a pig's bladder for the stomach, he injected tartar emetic into the veins, and vomiting followed. But he forgot that pressure might readily empty a dead bladder and have little effect on a living stomach. And that such is the case we may be certain, else every cough would evacuate the stomach. Lastly, the diaphragm acts the part of a sep- tum or mediastinum to separate the two great cavities between which it is placed. When this septum is wanting, the abdominal viscera get into the thorax, and in such cases the lungs are constantly found in a rudimentary state : their further evolution being impeded by the pressure exerted on them by the intruding viscera.* It has been stated that the oesophageal open- ing may be closed by those fibres of the crura which curve round it. The other openings, as the aortic, and that for the ascending cava, can- not be diminished by the efforts of the muscle. This is plain from the tendinous margins which they present, and the manner in which the mus- cular fibres are attached to their borders. We have not mentioned some of the uses which the ancients ascribed to the diaphragm — as, that it is the seat of the passions,f that it prevented noxious vapours from rising into the thorax, that it fanned the hypochondria, and so forth. These are too fanciful to demand serious notice. Malformations and diseases. — The dia- phragm may be absent in whole or in part by congenital malformation. In the very young foetus the thorax and abdomen form one cavity, as in birds, reptiles, and fishes ; and the deve- lopment of the diaphragm, as of most other organs, is by a process of growth from the cir- cumference to 'the centre. If, therefore, an arrest of formation occur at a very early period of foetal existence, the muscle may be entirely wanting; if at a later period, some deficiency will be found at or near the centre. An exam- ple of the total absence of the diaphragm was dissected by Diemorbroeck. The subject lived to the age of seven years without suffering any inconvenience except a frequent cough. J Con- genital deficiencies near its middle are not very rare. They are observed oftener towards the left than the right side, and are always accom- panied with a protrusion of the abdominal viscera into the thorax, not vice versa. The development of the thoracic viscera is impeded by this intrusion, and they remain more or less * Andral's Pathological Anatomy, tr. by Town- send and West, vol. i. t The word phrenic, used with reference to the diaphragm, as phrenic nerve, phrenic centre, &c. has its origin in this opinion, p£Vif, a ), situated on the second portion of intestine. This last-mentioned vessel, which may be con- sidered as the great pulmonary vein, sends branches on the intestine which open into the wide part of the main artery, and thus the blood is carried to the place whence it set out. According to Delle Chiaje, the principal vein, after diminishing in width, opens into the oblong sac which is connected with the vessels of the feet, and out of this bag six vessels issue. One of these is the great artery, which runs along the intestine ; the other five are the vessels of the tentacula and feet previously described; each of them sends four branches forwards to the tentacula, and a long one backwards between the longitudinal muscles to the vesicles of the feet. 5. Nerves. — Tiedemann discovered a nervous system in the star-fish. He describes it (in A. aurantiaca) as consisting of a delicate white cord surrounding the mouth, in form of a ring immediately on the outside of the circular vessel into which the heart opens, and of di- verging filaments which arise from the annular cord opposite the rays. ( Fig. 23.) There are Fig. 23. c,feet ; e,feet cut across ; f, apertures for the feet. three filaments for each ray; one runs along the under surface in the median line, and ap- pears to send small branches to the feet ; the other two, which are shorter, pass between the first and second segment of the ray into the interior of the body, and are probably distri- buted to the stomach. Tiedemann could dis- cover no ganglia, but others describe minute ganglia as existing at the points where the diverging filaments originate.* The Echinodermata have not generally been supposed to possess any other sense than that of touch. Professor Ehrenberg has how- ever recently called attention to certain parts in the Asterias, which he is disposed to re- gard as organs of vision.f These have the ap- pearance of small red spots, one of which is seen at the extremity of each ray. They have been long known to exist in several species of Asterias, but no one ever assigned to them any particular use till lately, when Professor Ehrenberg, struck with their resemblance in aspect to the eyes of Entomostraca and Infusoria, conjectured that they might be of the same nature. He states that he has traced the long nerve of the ray as far as the extremity, where it swells into a sort of ganglion with which the red point or supposed eye is connected. In the Echinus Tiedemann observed fine filaments on the internal surface of the mem- brane which fills the inferior opening of the shell, and on the dental apparatus and the longitudinal vessels of the feet, from which he inferred that a nervous system probably existed in the Echinus analogous in form to that of the Asterias. In the same way he was led to sus- pect the existence of such a system in the Holothuria, though by dissection he could make out nothing more than several exceedingly delicate filaments, some of which were situated in the neighbourhood of the mouth, and ap- peared to enter the tentacula, and others lay on the longitudinal muscles. Dr. Grant de- scribes a connected nervous system in the Echi- nus and Holothuria, but without mentioning on whose observations his description, which we here transcribe, is founded. " A nervous chord," he states, " is seen round the oeso- phagus of the Echinus, which sends delicate white filaments to the complicated muscular and sensitive apparatus of the mouth ; other nerves are seen extending upwards from the same oesophageal ring, along the course of the vessels in the interior of the abdominal cavity. In the Holothuria the nervous sys- tem is extensively developed. Interior to the osseous apparatus of the mouth is a white nervous ring around the oesophagus, from which nerves pass outwards to the large ramified tentacula around the mouth, and others extend upwards along the course of the eight strong longitudinal muscular bands. Fine white filaments are likewise seen passing inwards to the stomach and alimentary ap- paratus."! In a recent notice of some obser- vations on the Echinus by M. Van Beneden, it is stated that he distinctly recognized a nervous collar surrounding the oesophagus. 6. Generative organs. — The only organs hitherto discovered in the Echinodermata, which * Grant's Comparative Anatomy, p. 184. t Miiller's Archiv fiir Anatomie, Physiologie, &c, 1834. p. 577. X Comparative Anatomy, p. 184. ECHINODERMATA. 45 can with certainty be regarded as belonging to the generative system, are the ovaries, which are found in all. These animals would there- fore appear to have no distinction of sex. Whether the concurrence of two individuals is in general necessary for propagation is uncer- tain ; O. Fabricius affirms it of the star-fish, but further observation would be required satis- factorily to establish the fact ; he says " con- greditur" (Ast. rubens) " mense Maio, oribus arete connexis, altera supina."* a. The ovaries of Asterias seem to vary in number according to the species. In A. rubens and aurantiaca there are ten, two being situated in each ray, above the vesicles of the feet. Each of these organs consists in the former species of an oblong cluster of ramified tubes, (Jigs A 2 and 16, o, and ato', cut short), proceeding all from a single stem by which the organ is fixed, and terminating in round vesicular dila- tations. In A. aurantiaca the tubes are not all connected by a single stem, but form about twenty fasciculi, each of which has a distinct attachment (jig. 22, o, u ). The vesicles contain a whitish pulpy sub- stance, with which they are more or less dis- tended according to the season of the year; so that the ovary, varying thus in size, is found to occupy sometimes a greater at other times a less extent of the ray, to the commencement or base of which it is attached. Tiedemann could discover no excretory duct of the ovary; and nothing positive is known as to the way in which the ova are formed and discharged from the body. Tiedemann conjectures that they escape by openings situate in the neigh- bourhood of the mouth, in the angles between the rays. The Ophiurahas also ten ovaries, which do not lie in the rays, but in the central part of the animal, and which, according to Meckel, open externally by orifices on the ventral sur- face. b. The Echinus has five ovaries, (fig. 10, c,) attached to the inside of the shell in the upper part of the body, and occupying the spaces between the five rows of feet. They are often joined together laterally. They consist of an assemblage of small round bodies, which are the ova. Five short tubular oviducts come from the upper end of the ovaries and open externally by an equal number of orifices, pierced in five oval plates which surround the anus. The size of these organs, as in the star- fish, varies much according to the degree of maturity of the ova. The ovary, or row as it is named, is the part used as food. Mr. Pen- nant states that the E. esculentus is " eaten by the poor in many parts of England, and by the better sort abroad ;" in ancient Rome the Echini formed a favourite dish at the tables of the great. c. The ovary of Ilolothuria tubulosa (Jig. 34, m, p. 109, vol. i ) is situated at the fore part of the body near the stomach and first portion of the intestine. It is a tube with many clus- tering branches, which terminate in blind and * Fauna Gvocnlandica, p. 368. slightly dilated extremities. The main tube or oviduct runs forwards along the stomach, and opens externally on the dorsal aspect of the body a little way behind the mouth. Between the insertion of its branches and its external orifice, eight or ten pyriform vesicles open into it, close to each other, by long tubular pedi- cles. The size of the ovary varies excessively at different periods ; its branches usually contain a whitish fluid ; but Tiedemann states that about the end of October he has in some in- stances found the organ enlarged to twice or three times its usual dimensions, and con- taining oblong brown-coloured bodies from half a line to a line in length, which he sup- poses were eggs or perhaps embryos. From a statement of O. Fabricius it would appear that the Hoi. pentactes is ovo-vivi parous : he says, " est vivipara : mense enim Martio in ilia versus anum pullum libere natantem, rubicundum vidi."* The pyriform vesicles are found en- larged at the same time with the ovary itself, and Tiedemann conjectures they may be male organs, by which a fecundating fluid is produced and applied to the ova. 7. Regeneration of lost parts. — The star-fish affords an example of great regenerating power. Individuals are often found which have evi- dently sustained the loss of one or more rays, and in which new rays, as yet incomplete in their growth, occupy the place of the old. Experiments have been even purposely made which were attended with the same result; but we are not aware that the process of regeneration in these animals has been care- fully traced in its successive steps, or at least fully described. In 1741 and 42, Messrs. Bernard de Jussieu, Guettard, and Gerard de Villars made observations and experiments on this subject at various parts of the coast of France. These researches were undertaken at the request of M. de Reaumur, who thus de- scribes them. " They (M. de Jussieu and Guettard) brought me specimens of star-fish with four large rays and a small one still growing ; they found others with only three large and two extremely small rays ; others again with two large rays and three very small, and, as it seemed, very young ones. Lastly they more than once met with a single large ray from which four small ones had begun to sprout." After remarking that the fact had been long familiarly known to the fishermen, M. Reaumur continues, " The portions into which Messrs. Jussieu and Guet- tard had divided the animals appeared to go on well, the wounds cicatrized and consoli- dated, but the experimenters were obliged to limit their stay on the coast to about fifteen days ; too short a period to trace the progress of a reproduction which apparently is not completed till after several months, or perhaps even upwards of a year."-f BlBLIOGKAPH Y.— Kleinius, Naturalis dispositio * Fauna Groenlandica, p. 353. f Reaumur, Memoires pour servir a l'histoire des insectes, tome vi. preface, page lx. sq. 46 EDENTATA. Echinodermatum, 4to. Lips. 1778. Linkius, De stellis marinis, fol. Lips. 1733. Blainville, Diet, des Sc. Nat. art. Oursin. Tiedeinann, Anatomie der Rohrenholothurie, &c. Heidelberg, 1820. Eh- renberg, in Meckel's Archiv fur Anat. &c. 1834. Delle Chiaje, Memorie sulla storia degli animali senza vertebre del regno di Napoli. (W. Sharper/.) EDENTATA. — A group of mammiferous animals, exhibiting no very distinct general characters to indicate any close mutual affinities between them, but agreeing in the unimport- ant character of the absence of incisive teeth and the possession of long claws. They may indeed be considered as consisting of two very distinct groups ; the one exclusively vegetable feeders, the other generally insectivorous in their habits. To the first belong the Sloths ( Brudypm ), (fig. 24), constituting the Tar- digrada of Illiger ; to the second, the Ant- eaters ( Myrmecophaga), ( fig. 25), the Arma- dillos ( Dasypus), ("^g. 26), the Pangolin ( Ma- nis ) (fig. 27), with their congeners, and the re- cently discovered American fossorial animal, the Chlamyphorus, forming the Edentata proper. The enormous extinct animal, the Megathe- rium (Jig. 28), may be considered as an addi- tional form, and a very interesting and impor- tant one, as it certainly exhibits some charac- ters which appear to connect the Tardigrada and the true Edentata. The organisation of these forms is so different as to require a se- parate description. The Ornithorynchus and the Echidna are necessarily excluded from the Edentata, with which they had been united by Cuvier and others, and form the group called Monotremata by Geoffroy. In the Sloths, the whole structure is evidently formed to enable them to pass their life in trees, amongst the branches of which they con- stantly reside, hanging with the back down- wards and creeping slowly along in this remark- able position, embracing the bough, and Skeleton of the Ant-eater, EDENTATA. Fig. 26. 47 Skeleton of the Armadillo. Fig. 27. Skeleton of the Mams. Fig. 28. Skeleton of the Megatherium. stretching out their hands, which in the AY or Bradypus tridactylus are of great length, to enable them to lay hold of the extreme twigs, and bring them to the mouth. Their progres- sion on the ground is excessively slow and awkward, and should they be obliged to have recourse to it either from accident or from being forced by famine to seek a new tree on which to obtain their subsistence, they quit it as speedily as their peculiar organization will permit, and ascend the nearest tree with an awkward attempt at alacrity. The whole of their structure is admirably adapted to these extraordinary habits; and although upon a comparison of these slow-moving creatures with the active and intelligent and elegant ani- mals which form the more conspicuous groups of the Edentata, they may appear to possess but few advantages of structure, and little to excite interest in their habits, yet a careful investigation into the relation between their organization and their mode of life will shew that not even in the most elevated forms of the animal creation, does the wisdom of the 48 EDENTATA. Creator display itself more fully than in the construction of these contemned and apparently apathetic beings. I must refer the reader to a highly interesting paper by Professor Buck- land in the Linnaean Transactions, in which the libels of Cuvier on this maligned animal are beautifully and satisfactorily refuted. The Ant-eaters and Armadillos, on the other hand, which may be considered as the true Edentata, are constructed for very different habits, and the Chlurnyphorus must be consi- dered as offering a very near affinity to the latter genus. The Ant-eaters with their thick long hair and fossorial claws, and the long ex- tensile tongue with which they are furnished, are thus enabled to scratch or dig up the ant- hills and to receive their minute but multi- tudinous inhabitants on the mucous surface of the tongue; whilst by their long dense hair they are protected from the annoyance or dan- ger which their little troublesome victims would otherwise inflict. The Armadillos and the Chlamyphorus, on the other hand, pursue their insect prey either on or beneath the sur- face of the earth, and are protected from the attacks of their enemies by the panoply of mail with which they are furnished. The osseous system. The cranium. — The ge- neral character which at once strikes us in look- ing at the cranium of the Sloths (Jig. 29) is its Fig. 29. Head of the Sloth. extreme shortness, particularly with regard to the facial portion, and the roundness of its whole contour. In the insectivorous forms the muzzle, on the contrary, is greatly elongated. The frontal bone in the Tardigrada is large, and the anterior portion convex ; it has no zygo- matic process, and the frontal and orbital por- tions pass into each other by a very obtuse angle. The parietal bone in most is of a square figure. In the Armadillos (fig. 30) and in the Fig. 30. Head of the Armadillo. Orycteropus the two parietals are united from an early period ; in the Ant-eaters, on the con- trary, they remain separate. In the Sloth the squamous portion of the temporal bone is of large dimensions, and the acoustic portion of but moderate size. The zygomatic process is small and does not reach the jugal bone ; a con- struction which is still more conspicuously seen in the Ant-eaters. The occipital bone is large ; the squamous portion broad and rounded, the superior part being continued to the inferior by an obtuse angle in the Sloths, and by nearly a right anglein the true Edentata. The occipital foramen is round. The jugal bone offers some remarkable peculiarities in its form. In the Ant-eaters (Jig. 31) it occurs in a Fig. 31. Head of the Ant-eater. very imperfect condition, being merely an ob- long plate of bone, terminating posteriorly in a rounded point, situated in the posterior ex- tremity of the superior maxillary bone, and beneath the lachrymal, extending posteriorly scarcely beyond the latter ; consequently it is remote from the temporal bone throughout the whole length of the temporal fossa, and there is no zygomatic arch. In the Munis (fig. 32) it is absolutely wanting. In the Arma- Fig. 32. Head of the Manis. dillos it is somewhat more fully developed ; it is larger and higher and reaches the tem- poral bone by its posterior portion. In the Sloths, especially in the Bradypus diJactylus, or Unau, it attains a much greater size, and has on its inferior margin a long process extending downwards and backwards almost to the base of the lower jaw. This remarkable process is also found in the enormous fossil animal the Megatherium (Jig. 33). The posterior extremity of the jugal bone is remote from the zygomatic process of the temporal in the Sloths, but in the Megatherium these bones are united, and the zygomatic arch is therefore complete. The in- ferior maxillary bone varies excessively in this order. In the Orycteropus, Manis, and Myrme- cophaga, it is extremely long and depressed ; its height does not greatly vary in the whole of its length. In the Armadillos it is much shorter, and in the Sloths it is extremely short and trun- cated. The intermaxillary bone is excessively small in the Ant-eaters and the Sloth, which are not furnished with any incisive teeth, but in Armadillos it attains a somewhat greater degree of development, especially in the genus Da- EDENTATA. 49 Fig. 33. Head of the Megatherium. sypus. The inferior maxillary bone varies no less in its form in the different genera of this incongruous order than the superior. It is greatly elongated and very slender in the Edentata proper, particularly in the Ant-eaters ; the ascending plate is thin and small, the right and left branches of the bone are united at the symphysis to a considerable extent, and at a very acute angle. In the Sloths this bone ex- hibits a very different structure; it is short and deep, the ascending plate is broad and almost square, the angular process is very large, and the two branches of the jaw unite at the symphysis without an angle, the anterior por- tion of each side being curved inwards to meet its fellow. In the Megatherium the body of the bone is still higher and shorter, but the an- terior part is prolonged into a narrow and de- pressed groove somewhat similar to that of the elephant. The vertebral column. — The variation in the form and construction of the vertebra will be found to bear an exact relation to the habits of the different genera. The cervical vertebra of the A'i, Bradypus triductylus, have always, until very recently, been believed to form an excep- tion to the general law, which assigns seven as the strict number of these bones in the mam- miferous animals. That this number should exist equally in the hog and the giraffe is in- deed a remarkable fact, and may be considered as a striking illustration of the law by which variations in volume in any particular system of organs are provided for rather by the differ- ence in volume or in the relative proportions of the organs themselves, than by any abrupt change in their number. The supposed excep- tion to this law which now comes under our notice consists in the fact that the neck of the animal in question, (speaking of the part rather in reference to its use than in strict ana- tomical language,) is formed of nine vertebrae. Two skeletons in my own possession, however, have enabled me to demonstrate that the posterior two of these vertebrae (Jig. 34) have attached to them the rudiments of two pair of ribs in the form of small elongated bones articulated to the transverse processes of these bones, which are therefore to be considered as truly dorsal ver- tebrae, modified into a cervical form and func- tion, suited to the peculiar wants of the animal. The object of the increased number of ver- tebrae in the neck is evidently to allow of a more extensive rotation of the head ; for as VOL. II. Fig. 34. Neck of the Sloth. each of the bones turns to a small extent upon the succeeding one, it is clear that the degree of rotation of the extreme point will be in pro- portion to the number of moveable pieces in the whole series. When the habits of this extraordinary animal are considered, hanging as it does from the under surface of boughs with the back downwards, it is obvious that the only means by which it could look downwards towards the ground must be»by rotation of the neck ; and as it was necessary, in order to effect this without diminishing the firmness of the cervical portion of the vertebral column, to add certain moveable points to the number possessed by the rest of the class, the ad- ditional motion was acquired by modifying the two superior dorsal vertebrae, and giving them the office of cervical, rather than in- fringing on a rule which is thus preserved entire without a single known exception. In the two-toed Sloth there is but one pair of these rudimentary ribs, and consequently only the first dorsal vertebra enters into the compo- sition of the neck. The dorsal portion of the vertebral column is particularly long in the Ant-eaters as well as the Sloth. These vertebrae are also generally more numerous in this than in most other groups— the great Ant-eater having sixteen, the A'i fourteen, and the (Jnau no less than twenty-three — a larger number than is found in any other mammi- ferous animal. The ribs offer some striking peculiarities in their construction. In the Ant- eaters and Armadillos they are excessively broad with the exception of the first and second. In the Myrmecophaga jubala and M. didacti/la they overlap each other in an imbricated man- ner on the upper part, — a conformation which gives great solidity to the chest. The Sloths and the Megatherium exhibit also considerable breadth of the ribs, but to a much less extent than that just described, and the latter animal, E 50 EDENTATA. at least in the remains lately described by Mr. Clift, the part joining the sternum, and answer- ing to the cartilages of the ribs, is bony and is connected to the rib itself by a moveable arti- culation. The lumbar vertebra are generally broad and furnished with strong spinous pro- cesses. The transverse processes are incon- siderable in the Sloths, but large in the Edentata proper. In the Armadillos the anterior articu- lar processes are particularly strong and larger even than the spinous. This is the case, but to a less degree, in the Ant-eaters. In the Orycte- ropus there are slight indications of inferior spinous processes on most of the lumbar verte- bra, consisting of a small longitudinal crest. The caudal vertebrae vary excessively in num- ber. In the Unau and Bradypus didactylus they are very few — not more than seven or eight ; in the large Ant-eater forty, and in the African Manis forty-five. In the remains of the Megatherium lately deposited in the Mu- seum of the Royal College of Surgeons, the tail would appear, according to Mr. Clift's computation, to consist of eighteen vertebrae at least. The caudal vertebra? of the Edentata proper have inferior spinous processes of a remarkable form, being constituted of two branches meeting inferiorly in the median line. The Megatherium possesses similar V-shaped processes. In the Myrmecophaga didactyla the two branches are not united in the anterior two of them. The sternum offers a considerable developement of themanubriumor anterior bone in the whole of the Edentata, particularly in the Ant-eaters and Armadillos. It is also rather large in the Megatherium. The pelvis in the Edentata proper is much elongated, and the acetabulum rather behind the middle of the whole length of the bones. The ileum, which forms the anterior half of the pel- vis in the Armadillo, is fixed to the sacrum by its posterior portion, a surface of considerable extent. The ischium and pubis are large, the is- chiatic notch wide, and the cavity of the pelvis capacious. In the Sloths and Megatherium the pelvis is of large dimensions, the ilia very broad, especially in the latter ; the cavity capa- cious, and the outlet large. The ossa pubis are joined at the symphysis in most of the Eden- tata, as is now ascertained by Mr. Clift, in the Megatherium . In the Myrmecophaga didac- tyla, it is stated by Cuvier to be open. The size of the pelvis in the Megatherium is enormous. On comparison of it with the pelvis of an elephant eleven feet in length, Mr. Clift found that in the former the ilia are 5ft. lin , and in the latter only 3ft. 8in. The anterior extremity. — The principal cha- racteristic of the bones of the arm in the Sloth is their extraordinary length. The humerus is very much elongated and cylindrical, with the elevations but slightly marked. The ulna and radius axe ajso very long, and bowed, so that the bones are distant at the middle of their length ; the radius is very broad anteriorly. The very complete power of pronation and su- pination enjoyed by this animal is no less ob- viously suited to its habits than the great length of its anterior extremities ; both of which peculiarities are admirably subservient to the complicated objects of holding by the boughs, of advancing along their under-surface, and of reaching and bringing to the mouth the leaves on which it feeds ; and the structure of the hand (Jig. 35) is no less suited to the same pur- Pig. 35. Hand of the Sloth. poses. The carpus is as long as it is broad ; it is composed of six pieces only, of which four form the first series, and two the second. The os scaphoides is the largest of the whole, and is articulated with the os semilunare by a convex articular surface : the os cuneiforme presents on its ulnar side an oblique flattened surface ; the os pisiforme, which is not named by Cuvier, does however exist, though it is of small size. The inner and larger piece of the anterior series probably consists of the as trapezium, trape- zoideum, and magnum united; and the external one solely of the os unciforme. In the Unau the os trapezoides is distinct. The metacarpal bones, to return to the AY, consist of three per- fect and two rudimentary, the whole of which are united at their base to each other and to the inner solid carpal piece, consisting of the three bones before mentioned; so that in fact the five metacarpal bones, with the os trapezium, tra- pezoideum, and magnum, form one solid osseous piece. The fingers, which are three only, are very long, and consist each of two moveable phalanges only, the first being very small and early anchylosed to the metacarpal bone. In a very young skeleton in my possession, these bones are not yet united. There is but very little flexion between this part and the second phalanx, but between the latter and the third or ungueal phalanx the flexion is complete, the latter being bent down to the palm with perfect ease. These ungueal bones are very long, curved, laterally compressed, large at the base, at which part there is, as in the cats, a bony sheath to cover the base of the claw ; and the latter envelopes the phalanx for about five-sixths of its length. The posterior extremity in this remarkable animal offers no less striking peculiarities. The breadth and openness of its pelvis have been already noticed. Fhefemur is articulated to the acetabulum so as to stand obliquely outwards from the pelvis ; it has a short head, and is it- self rather short, strong, and flattened. The tibia and Jibula are long and slender, and some- what curved ; the superior articular surfaces of the tibia are flat, that of the inferior extremity EDENTATA. 51 small, triangular and slightly concave ; but the most extraordinary articulation is that of the fibula with the astragalus; its inferior extremity terminates in a conical point, which enters and plays in a corresponding cavity in the latter bone. This peculiarity of the articulation of the ankle, which was considered by Cuvier as only additional evidence of the imperfection of the animal's structure, is no less admirably adapted to its habits than those points which have been previously noticed. The feet, it is true, are turned inwards, and there is no pos- sibility of placing the sole on the ground; but it is the better adapted for clasping boughs, and the freedom of rotation which is provided by this curious joint allows of every kind of motion required in such circumstances. The tarsus consists of the astragalus and os calcis, which are separate, and of the usual anterior series of bones, which in the aged individuals are anchylosed together as well as to the meta- tarsal bones, which are themselves united as in the carpus. The tubercle of the os calcis is very long, and so situated as to afford a sort of opposing thumb to the flexed phalanges. The latter bones very nearly resemble those of the anterior extremity. It is impossible not to be struck, even on a superficial view of the extraordinary structure of the anterior and posterior extremities of the Sloth, with the complete adaptation of this deviation from the normal form to its peculiar mode of life. Grasping the boughs of trees on which it both feeds and reposes, crawling along with the back downwards and the belly pressed against the tree, and culling, with the long arms, the leaves at the inaccessible extre- mities of the branches, the usual construction of the members would be absolutely useless, and an incumbrance instead of an assistance. But by the great breadth of the pelvis, the di- rection of the femora, the long and curved claws, the consolidation of the tarsus, and the curious structure of the articulation of the fibula with the astragalus, every requirement of security and progression is obtained; whilst in the an- terior extremity the extensive motion of the shoulder-joint, the great length of the arms, the complete flexion of the fingers, and other peculia- rities, combine, with that security and facility of progression, the most effective means of ob- taining the animal's peculiar food. Of the Edentata proper. — The extremities in animals of this class are, as may be con- cluded from their habits, very differently constituted from those which have just been described. In all of them the object to be obtained is facility in digging the ground, or scratching up immense nests, in search of the insects which constitute the principal food of most of these animals. The gigantic Megatherium, however, appears to have combined the phytopha- gous character of the Sloth with the fossorial habits of the Dasy- pus, and is supposed to have lived upon roots, which it snatched or dug up with its enormous claws. The scapula of theA.nt-eaters and Armadillos is found nearly like that of the Sloth ; in the Myrmecophagajubata a process of bone extends from the coracoid process to the anterior margin, rendering that which is a notch in other species a complete foramen. A second spine inferior to the true one is also observed in that species, in which respect it resembles the Unau or two-toed Sloth. The scapula of the Armadillos is very high and narrow. In that of the Mega- therium there exists a large process of bone ex- tending from the coracoid process to the acro- mion,andthus completely uniting theseprocesses. The clavicle exists in many of the Edentata, as the Armadillos and Ant-eaters, but is wanting in the Manis or Pangolin. That of the Megathe- rium offers a remarkable peculiarity. It extends from the acromion, not to the sternum as in all other cases, but to the first rib. The humerus is in most of the order very short and robust, and its elevations strongly marked. In the Ant-eaters the part above the inner condyle is extremely developed, to give attachment to the powerful flexors of the claws ; and the crests for the in- sertion of the deltoid and great pectoral muscles are very prominent and angular, — a structure which is also conspicuous in the Armadillos and Manis. The humerus of the Megatherium has a similar general form; it is rude, short, and excessively strong, with abrupt and large ele- vations for the different muscular attachments ; the inferior part especially becomes suddenly larger, from the existence of a strong and ele- vated external crest. The habits of the Edentata proper demand a very different construction of the fore-arm from that of the Sloth. Requiring immense strength in digging the ground, the short ole- cranon which exists in the Sloth would be wholly inefficient. A long lever is necessary, and hence we find that in the whole of these the olecranon is of an extraordinary length, and that in the Megatherium its more moderate length is compensated for by its immense strength. In the five-toed Armadillo this pro- cess is so extensive as to render the ulna no less than twice the length of the radius, and in the other species of the same genus it is not much less. Trie radius is broad, robust, and strongly marked, particularly towards the carpal extremity. The hand in the Myrmeco- phuga (fig 36) and its kindred genus Manis Fig. 36. Hand of the Ant-eater. E 2 S3 EDENTATA. offers a very remarkable structure. The ungueal phalanges, like those of the Sloth, are restricted in their motion to simple flexion, in which position they are retained during repose by Strong ligaments. In the Myrmecophaga the terminal phalanges are deeply grooved in the margin ; in the latter they are bifid. The pha- langes of the fingers themselves are very une- qual in length and thickness. The middle finger is of extraordinary size, every articula- tion being very robust, and almost twice as thick as either of the others; the next on each side are nearly as long but much smaller, and the outer shorter still and very slender. The outer finger has no claw ; the four others are furnished with claws. The hand in Dasypus and Orycleropus is also of a very remarkable conformation, particularly in the gigantic spe- cies of Armadillo, Priodunta gigantea (Jig 37) Fig. 37. Hand of the Gigantic Armadillo. of Fr. Cuvier. Amongst the peculiarities of structure in this animal are the following. In addition to several remarkable anomalies in the carpal bones, the bone which results from the ossification of the flexor profundus muscle is very large, developed posteriorly into a large and irregularly formed head, articulated by large surfaces to the os semi- lunar and pisiforme, presenting concave sur- faces on the side of the fore-arm, and termi- nating towards the hand by an enlargement which is compressed and smaller than the head. The metacarpals are no less extraordinary. Those of the thumb and index, as well as their phalanges, are slender, of the usual construc- tion, but that of the middle finger is irregularly rectangular and broader than it is long ; and the phalanx which it supports is of a corresponding form and size, being extraordinarily short and broad. The corresponding bones of the fourth finger are similarly formed, but somewhat smaller. The ungueal or terminal phalanx of the middle finger is enormously large and strong, curved outwards, and having at its base a large bony hood or case for the lodgement of the claw; the terminal phalanx of the fourth finger is similar, but of somewhat smaller di- mensions. The fifth or little finger is much smaller, but is furnished with a claw of some size. The conformation of the hand of this animal affords a most formidable weapon, or as a powerful fossorial instrument, in the three outer claws, whilst the two inner ones are only formed for scratching or other similarly slight actions. The posterior extremity of the Edentata proper offers perhaps less striking peculiarities of structure. The femur in general is of mo- derate length, but large and strong; and an elevated crest, arising from the great trochanter, extends nearly the whole length of the bone. In the Ant-eaters and the Megatherium, it is particularly broad and flattened, and the greater and lesser trochanters are not particularly pro- minent. In the genus Dasypus the great tro- chanter on the contrary is of great size, and from the middle of its outer margin arises a large process which is directed outwards. The tibia and fibula in the latter genus are extremely broad, arched, and anchylosed at both extremi- ties. In the Ant-eaters, on the other hand, these bones are of the ordinary form, and have no osseous union. In the Megatherium they are united by the superior third of their length, and closely in contact at the lower part ; they are both short and extremely thick, particularly the tibia. The tarsus is composed in the two-toed Ant-eaters of at least eight distinct bones, the largest of which is a supernumerary ' bone, situated at the inner part of the 5335^s foot, upon the scaphoid; it extendsback- wards as far as the tuberosity of the os calcis, and thus forms a broad base Ik to the posterior part of the sole of the \ 11 foot. The Myrmecophaga jubata has \ 1 also a supernumerary bone, but of t/ smaller dimensions ; but the Armadillos and Orycteropus have but the seven or- dinary bones of the tarsus. The metatarsal bones and the toes are probably invariably five throughout the Edentata proper; the toes of the posterior extremity offer few peculiarities of any consequence. Both the anterior and poste- rior feet of the Megatherium are peculiar in their structure. In the former, those fingers which are completely formed are the three middle ones, the little finger being rudimentary, and the thumb having no claw. The ungueal pha- langes of the three former are enormously deve- loped, principally as regards the bony enve- lope for the base of the claw ; the size and thickness of which indicate that the claws themselves must have been of great size and immense strength, and have afforded powerful implements for tearing up the suiface of the ground in search of roots. On the hinder foot, there is a single toe of a similar con- struction, which is the third ; the fourth and fifth, although of considerable size, bore no claws. This enormous extinct animal is cer- tainly among the most extraordinary produc- tions of the ancient world. Of dimensions the most unwieldy, and with a skeleton as solid as that of the most enormous amongst the Pachy- dermata, we find a cranium, and especially teeth, which exhibit a very near relation to those of the Sloth, and members which are no less remarkably allied to the Ant-eaters and the Ar- madillos. However the difference in bulk may iippear at first sight to interfere with the idea of these affinities, and however difficult it may be at once to reconcile the relation between a small active animal like the Armadillo, or an inhabitant of trees like the Sloth, and this enormous and unwieldy tenant of the earth's earlier surface, the affinities are neither less true nor more probable than those which subsist between the light rabbit-like hyrax EDENTATA. 53 and the ponderous rhinoceros of the present world. There is still another very interesting animal, the account of whose osteology I have not in- termixed with that of the other Edentata, be- cause it is as yet but little known, and because its peculiarities are particularly interesting. This is the Chlamyphorus truncatus (fig- 38) of Dr.Harlam, of which I have the opportunity of animals belonging to the same order. To the Echidna and Ornithorynchus it is also similar in the first bone of the sternum, and in the bony articulations as well as the dilated con- necting plates of the true and false ribs. " In the form of the lower jaw, and in other points equally obvious, the Chlamyphorus ex- hibits characters to be found in some species of Ruminant ia and Pachydermuta. On Skeleton of the CMamyplwrus truncatus. offering a very correct figure, for which I am indebted to the kindness of my friend Mr. Yarrell. This very remarkable animal was discovered in the interior of Chili, burrowing like the mole, and like that animal residing principally underground. The detail of its organization will be found, as given by Mr. Yarrell, in the third volume of the Zoolo- gical Journal, to which I refer. The general results of that gentleman's observations are as follow : " It has much less real resemblance to the mole, Talpa Europea, than its external form and subterranean habits would induce us to expect. In the shortness and great strength of the legs, and in the articulation of the claws to the first phalanges of the toes, it is similar ; but in the form of the bones of the anterior extre- mity, as well as in the compressed claws, it is perfectly different ; nor do the articulations of the bones nor the arrangement of the muscles, allow any of the lateral motion so conspicuous in the mole. The hinder extremities of the Chlamyphorus are also much more powerful. "It resembles the Brady pus tridactylus in the form of the teeth, and in the acute descending process of the zygoma, but here all comparison with the Sloth ceases. " The skeleton of the Chlamyphorus will be found to resemble that of the Armadillo (Dasypi species plures) more than any other known quadruped. In the peculiar ossification of the cervical vertebrae ; in possessing the sesamoid bones of the feet ; in the general form of all the bones, except those of the pelvis, as well as in the nature of the external covering, they are decidedly similar ; they differ however in the form and appendages of the head, in the com- position and arrangement of the coat of mail, and particularly in the posterior truncated ex- tremity and tail. " There is a resemblance to be perceived in the form of some of the bones of the Chlamy- phorus to those of the Oryctcropus capensis and Murmecophaga jubata, as might be expected in this sketch of its relations it is unnecessary to dilate. Its near affinity to the genera Dasy- pus and Tatusia however is so obvious that there can be no doubt of the propriety of con- sidering it as belonging to the same family of the order; whilst its relation to the mole can of course only be considered as one of analogy, in which respect it offers many interesting characters." Digestive organs. — In the character of these organs there is no less diversity between the Turdigrada and the Edentata proper than in the osteology already described. The former, essentially herbivorous, yet living principally upon the young succulent leaves which clothe the extremities of the branches, have the teeth formed for bruising this kind of nourishment, and an articulation of the lower jaw which allows of a degree of motion commensurate with the object. The teeth consist of a cylinder of bone enclosed within a simple case of enamel, but without any of the convolutions of these two substances which characterize the structure of these organs in the Ruminantia and other graminivorous animals. They are in fact the most simple which are found in any of the Mammifera. There is a single canine on each side above and below, both in the Unau, but none in the Ai. In one form of the Armadillos, the genus Dasypus as now restricted, there are two in- cisive teeth in the upper and four in the lower jaw, and sixteen molares in each. In the allied genus Tatusia there are no incisive or canine teeth, and the molares are even rather more numerous, and in the Priodonta Gigas there are no less than fifty in the upper and forty-eight in the lower jaw. These are all simple, and formed for crushing insects. The stomach in the Sloths is very remarkably formed. In the Brady pus didactylus (Jig. 39) it is double. The first is large and rounded, con- tracted posteriorly, and produced into a conical appendix, which is doubled from the left to the right, and its cavity is separated from that 54 EDENTATA. Fig. 39. Stomach of the Sloth. of the stomach by a semilunar fold. The cardia opens very far towards the right side, leaving a very large pouch, and enters a canal which proceeds along the right side of the first stomach, giving off from its right margin a broad process, which separates the pouch of the stomach from the other cavity, which lies between the pouch and the appendix before mentioned. Thus the first stomach is divided into three cavities. The canal already described turns from the left towards the right, and enters the second stomach by a narrow opening. The second stomach is of a slender form, much smaller than the former ; its parietes are very thin for the first half of its length, but much thickened towards the pylorus ; and the two portions are sepa- rated by a semilunar fold. Again, the first portion of this second stomach is itself partially divided by a beautifully indented fold, the dentated processes of which are directed towards the pylorus. There is also attached to the second stomach a small cul-de-sac, which lies between two similar ones connected with the first stomach, the internal surface of all of which appears to be glandular. In the AT the appendix to the second stomach is much longer, and divided into three chambers by two membranous partitions. The whole of this structure, and especially the canal which extends from the cardia to the second stomach, indicates a very remarkable relation to that of the ruminants, and is evidently intended for the digestion of vege- table substances only. In the Edetitata proper the stomach is, as may be expected, far more simple. In the Myrmecophaga didactyla it is of a globular form, and simple. In the Manis pentadaclyla or Pangolin, it is internally divided by a fold into two cavities, of which the left, analogous to the paunch, is thin, and the pyloric, or true digestive portion, much thicker. The intestinal canal does not present the same striking distinctions between the large and small intestines which are observed in most other mammifera. There are in the Ant-eaters two ccecal appendices, which may be considered as forming the boundary between the two portions, of which the posterior is very much shorter than the anterior. It is remarkable that the entrance to these' small cceca is so contracted as wholly to prevent the passage of any faeces into them. In the Munis longicauda there is not the vestige of a coecum. In the Orycteropus it is short and oval. In the Turdigrada, the Ai for example, the large intestine is at once distinguished from the small by its sudden enlargement, and at their junction is found a slight fold, which partially separates them. The liver offers but few peculiarities of consequence in a physiological point of view. In the Ant-eaters, the Armadillos, and the Orycterope, it consists of three lobes. In the former the hepatic duct joins the cystic at a considerable distance from the neck of the gall-bladder, and, as in the Armadillo, at a very acute angle. Organs of circulation. — In a paper in the Philosophical Transactions, Sir A. Carlisle described a very remarkable peculiarity of the arrangement of the arteries of the limbs in several slow-moving animals, of which number were the Bradypus tridactylus and Bradypus didactylus. It appears that the axillary and iliac arteries, on entering the upper and lower limbs, are suddenly divided into a number of cylinders of equal size, which occasionally anastomose with each other. They are ex- * clusively distributed in the muscles. Those of the other parts of the body, and even those of the limbs which supply the bones, &c. do not deviate from the usual mode of distribution. In the former species no less than forty-two of these cylinders were counted on the superficies of the brachial fasciculus, and there were probably not less than twenty concealed in the middle. In the second species they were less numerous, and deviated from the usual form. This difference in the two species is perfectly consistent with what is known of their habits ; for there can be no doubt that the peculiarity has reference to the slowness of motion of these animals, in which character the Ai far exceeds the Unau. " The effect of this peculiar disposition of the arteries, in the limbs of these slow-moving quadrupeds, will be that of retarding the velocity of the blood. It is well known, and has been explained by various writers, that the blood moves quicker in the arteries near the heart than in the remote branches ; and also, that fluids move more rapidly through tubes which branch oft* suddenly from large trunks than if they had been propelled for a considerable distance through small-sized cylinders ; be- sides the frequent communications in the cylinders of the Bradypus tridactylus must produce eddies which will retard the progress of the fluid. From these and a variety of other facts, it will appear that one effect on the animal economy, connected with this ar- rangement of vessels, must be that of di- minishing the velocity of blood passing into the muscles of the limbs. It may be difficult to determine whether the slow movement of the blood sent to these muscles be a subor- dinate convenience to other primary causes of their slow contraction, or whether it be of itself the immediate and principal cause." The integument in the Manis as well as in ELASTICITY 55 the genera Dasi/pus and Tutmia, comprehend- ing the Armadillos, and in Chlumyplwrus, ex- hibits various modifications of a very extraordi- nary nature. The body of the Munis is co- vered with large imbricated scales, of a more or less rhomboidal form, of a horny consistence, and a reddish brown colour. The true struc- ture of these scales is undoubtedly a congeries of hairs, as is evinced in the longitudinal lines with which they are all marked. They form a very firm and complete protection to the animal when rolled up in a ball, which is its ordinary means of escaping from danger. The scales cover the whole surface, excepting the inferior part of the head and tail, the axilla;, the middle of the belly, the inner surface of the thighs, and the soles of the feet, all of which parts, excepting the latter, are furnished with a few scattered hairs. In the Armadillos an osseous crust or shell envelopes the whole of the upper part of the head and the body, the outer part of the limbs, and the whole of the tail. The inferior parts of the body are not thus protected, but scantly covered with hair, intermixed with a kind of hard warts or scales. Their armour is composed of a helmet covering the upper part of the head, of a buckler over the shoulders, a similar one over the crupper, and the back has numerous imbricated bands, which move upon each other, varying in num- ber in the different species; the tail is covered by rings, also allowing of motion. It is clear that this hard bony armour is capable of afford- ing these animals the most complete protection when coiled up, which is the position usually assumed by them when in danger, or during repose. Although there is mutual motion only at the margins of the different pieces and at the commissures of the bands, there is considerable yielding at every portion of this coat of mail. Each of the larger pieces is composed of nume- rous adherent smaller ones, hexagonal, and per- fectly tessellated ; those of the shoulders are arranged in segments of concentric circles, the concavity being in front, so that the anterior series, which is the shortest, embraces the neck of the animal. The covering of the posterior part has a similar arrangement, but reversed, so that the short concave margin meets the origin of the tail. The cuirass of the Chlamy- plwrus truncatus differs in many respects from that of the Armadillos, and is thus described by Dr. Harlam in the only account which we have of the details of this singular animal, with the exception of the very interesting descrip- tion of its osteology by Mr.Yarrell, in the third volume of the Zoological Journal. " The shell which covers the body is of a consistence somewhat more dense and inflexi- ble than sole leather of equal thickness. It is composed of a series of plates of a square, rhomboidal, or cubical form ; each row sepa- rated by an epidermal or membranous produc- tion, which is reflected above and beneath, over the plates ; the rows include from fifteen to twenty-two plates; the shell being broadest at its posterior half, extending about one-half round the body ; this covering is loose through- out, excepting along the spine of the back and top of the head ; being attached to the back immediately above the spine, by a loose arti- cular production, and by two remarkable bony processes ; on the top of the os fronds, by means of two large plates, which are nearly in- corporated with the bone beneath ; but for this attachment, and the tail being firmly curved beneath the belly, the covering would be very easily detached. The number of rows of plates on the back, counting from the vertex, (where they commence,) is twenty-four; at the twenty- fourth the shell curves suddenly downwards, so as to form a right angle with the body ; this truncated surface is composed of plates nearly similar to those of the back ; they are disposed in semicircular rows, five in number ; the lower margin somewhat elliptical, presents a notch in its centre, in which is attached the free portion of tail, which makes an abrupt curvature, and runs beneath the belly parallel to the axis of the body ; the free portion of the tail consists of fourteen caudal vertebra1, surrounded by as many plates, similar to those of the body ; the extremity of the tail being depressed so as to form a paddle ; the rest of the tail compressed. The caudal vertebra? extend up to the top of the back, beneath the truncated surface, where the sacrum is bent to meet the tail. The supe- rior semicircular margin of the truncated sur- face, together with the lateral margins of the shell, are beautifully fringed with silky hair.'' It is much to be regretted that but little is known of the generation of these animals. The dissections which have hitherto been made of the more interesting forms have been imper- fectly performed, or the subjects themselves have been in such a condition as to allow of but very incomplete observations. For BiBUo^A'rHiY, see that of Mammalia. ELASTICITY (Germ. Springkraft, Fe- derkrqf't) is that property of natural bodies in virtue of which they admit of change either of size or form from the application of external force, resuming, upon the suspension of that force, their proper shape or volume. Though elasticity is a purely physical pro- perty, its investigation is scarcely less interest- ing in physiological than in mechanical science. The most cursory examination of a living body is sufficient to convince us, that nature, in regulating its varied functions, has availed herself no less of physical than of vital laws. As it is the province of the physiologist to explain and analyze the several actions whose aggregate is life, to trace each to its proper source, and to distinguish those which are truly vital from those which are merely mecha- nical, it is plain that an acquaintance with the physical properties of the material elements of living bodies becomes one of the foundations of his knowledge. Hence, in a publication, the design of which is to present a complete view of the structure and functions of living 5(3 ELASTICITY. beings, it would be improper to omit some notice of those properties of' matter which are so frequently and so admirably employed in fitting them for their uses. In this article we shall offer, in the first place, some remarks upon elasticity generally, upon its laws, and upon the distinction between it and other forces ; we shall next advert to its existence in the organized tissues of the animal machine ; and, lastly, we shall point out some important actions in the living body where elasticity plays a principal part. I. General remarks on elasticity — its laws, fyc. — The degree of elasticity possessed by un- organized bodies is extremely variable; in some it is so great that they have obtained the name of perfectly elastic ; while in others this property is so extremely small, that its very existence has been overlooked. Air is the most perfectly elastic substance with which we are acquainted ; in experiments made upon atmospheric air a portion of it has been left for years subjected to a continued pressure, upon the removal of which under the same temperature and barometric altitude, it forth- with resumed its original volume. Amongst solid bodies, the most conspicuously elastic are certain metals and metallic alloys, glass, ivory, &c; while other solids, such as moist clay, butter, wax, and many similar substances, possess elasticity in an almost imperceptible degree. Fluids have long been considered as completely inelastic ; but though it is ex- tremely difficult to demonstrate this property, yet the experiments of Canton would seem to indicate its existence ; they place at least be- yond all doubt their possession of another property, namely, compressibility, — a pro- perty somewhat allied to that we are now con- sidering. The laws which regulate the elastic force are not exactly the same in these three classes of natural bodies. In the gaseous or perfectly elastic bodies elasticity may be said to deter- mine their volume : their particles having an incessant tendency to expand into a greater space are controuled merely by the surround- ing pressure, and hence the bulk of gases is always inversely proportional to the compres- sing force. This law, at least in the case of atmospheric air, applies within all known de- grees of condensation and rarefaction. By means of accumulated pressure, air may be so reduced in volume, that upon suddenly libe- rating it, as in the air-gun, it expands with amazing force ; and in the receiver of the air- pump, even when reduced to one-thousandth pirt its original quantity, it has still elasticity enough to raise the valve. Another important law of elasticity in gases is that its power is increased by heat and diminished by cold, and this applies not only to the permanently elastic gases but to those likewise of another kind, such as the vapours of alcohol, mer- cury, nitric and muriatic acids, and water ; the elastic vapours of the nitric and muriatic acids not unfrequently burst the vessels containing them ; the vapours of mercury have broken through an iron box ; and the vapours of al- cohol have sometimes occasioned in distil- leries the most terrible explosions : the elas- ticity of steam, and the fact that wg can in- crease its power to any extent by means of heat, has enabled us to construct the steam- engine, and thus armed mankind with a phy- sical power superior to every obstacle. Solid bodies are never perfectly elastic ; for although some, when acted upon by forces within a certain range, are as completely elastic as the gases themselves, yet if the disturbing force be carried beyond a certain degree, they will never resume their original condition. Thus, a harp-string gently drawn by the finger is thrown by its elasticity into vibratory mo- tions, returning when these have ceased to its exact original state: this may be frequently repeated and always with the same effect, as proved by the same note being repeatedly ob- tained. If, however, it be once drawn with too great a force, it no longer returns to its original condition, a different tone is now produced by it : in other words, the solid substance of which it is composed exhibits a perfect elasticity, not, as the gases, under every degree of force, but only within a certain limit. Heat pro- duces very different effects upon the elasticity of gaseous and solid bodies; we have just seen that we can increase the elastic power of the former to any extent by means of heat, but the elasticity of solids is, on the contrary, usually diminished by it ; very high tempera- tures completely destroy it even in the most elastic metals. The design of this article does not permit us to enter more fully into the con- sideration of those laws, or of the experiments by which they are demonstrated. We must refer for the further investigation of this sub- ject to works which treat expressly upon physics. The various hypotheses which have been put forth to explain the nature of elasticity, though many of them extremely ingenious, do not however properly come within the pro- vince of the physical much less of the phy- siological enquirer. Indeed, while men di- rected their attention to such speculations little or no progress was made in real knowledge. The cause of elasticity, like that of life, is probably beyond the sphere of human un- derstanding ; and hence, in both sciences, the method of investigation should be the same — to study the laws or conditions under which the phenomena present themselves, and to lay aside all speculations as to their causes. But in abandoning these inquiries into the nature of elasticity we must particularly advert to the necessity of the physiologist possessing a clear and definite idea of this property of matter, so as to be enabled to recognize it under every circumstance, and to distinguish it from other physical and vital forces. Ignorance upon this point has been at all times a fruitful source of error in physiological investigations. The pro- perty with which it is especially liable to be confounded is contractility : when it is re- membered that at one period of medic al his- ELASTICITY. S7 tory these two properties were looked upon as identical ; that even the illustrious Cullen has scarcely distinguished them, and that some of our most eminent living physiologists have fallen into manifest errors upon the same sub- ject, it becomes plain that we cannot be too particular in familiarizing ourselves with the distinctions between these totally independent forces. It is not enough to say that contractility is a vital and elasticity a physical property; for as we are ignorant alike of the nature of life and of elasticity, a distinction founded upon any such assumption must necessarily be futile. It is only by a diligent comparison of then- respective laws that we can assign to each its proper limits. Let us then observe in con- trasting them, first, that elasticity can never act as a prime mover; it is never a source of power, but merely the reaction of a force pre- viously applied : thus, the elasticity of the spring will never of itself set the watch in motion unless some external force shall, in the first instance, have acted upon or bent it. But contractility can of itself originate motion, at least it is not essential that any mechanical force with which we are acquainted should precede its action. Again, the force of elas- ticity can never exceed that other power which has called it into existence ; if, for instance, a weight of one pound be required to depress an elastic spring, the force of reaction upon the removal of that weight can never exceed the measure of a pound. But, in the case of muscular contraction, there is no such limit ; there is no fixed ratio between the cause and the effect; the slightest touch of a sharp in- strument will, in an irritable muscle, such as the heart, excite the most violent contractions. Elasticity cannot manifest itself except by the removal or suspension of the cause which has called it into action : muscularity requires no such suspension of its exciting cause. The exciting cause of elasticity is always of a phy- sical nature; but many other causes no ways allied to physical ones may excite the muscular power. Lastly, elasticity is not destroyed by death nor affected by opium or other narcotics, while contractility presents a very striking con- trast in both these respects. These facts are quite conclusive in proving that muscular and elastic contraction are go- verned by distinct laws, and cannot conse- quently be referred to the same source. But if some physiologists have erred in overlooking the distinctions between these two properties, if they have not analysed with sufficient care, others have unquestionably erred in an oppo- site direction, and by pushing analysis too far, have attributed to imaginary forces effects which are the result of elasticity alone. We feel much diffidence in controverting any doc- trine supported by the genius and authority of Bichat, but we confess that the distinction which that celebrated anatomist is so anxious throughout his various works to establish be- tween what he terms " contractility of tissue" and elasticity, appears to us unfounded. Elas- ticity according to him is a purely physical property. Contractility of tissue, though not actually a vital one, is however found only in the animal tissues; it does not depend directly upon life, but results merely from the texture and organization of those particles which con- stitute the vital organs. The following passage from his work upon " Life and Death" may, perhaps, assist us in understanding his views upon this subject. " Most organs of our bodies are held in a state of tension by various causes ; the voluntary muscles by their anta- gonists ; the hollow muscles by the substances contained within them ; the vessels by means of their circulating fluids; the skin of one portion of the body by that which covers the neighbouring part; the alveolar walls by the teeth contained within them. Now, upon the suspension of the distending causes, contrac- tion takes place: divide a long muscle, — its antagonist becomes shortened; empty a hol- low muscle, it shrinks upon itself: prevent the blood from entering an artery, the vessel be- comes a ligament: cut through the integu- ments, the divided edges are separated from each other by the contraction of the adjoining skin : extract a tooth from its alveolus, that channel becomes obliterated. * * * In all these cases it is the removal of a tension naturally inherent in the tissue which determines its contraction: — in other instances it is the re- moval of a tension which does not naturally reside in the part. Thus we see the abdomen contract after parturition ; the maxillary sinus after the extirpation of a fungous growth ; the cellular tissue after the removal of an abscess ; the tunica vaginalis after the operation for hydrocele; the integument of the scrotum after the removal of an enlarged testicle ; the aneurismal sac upon the emptying of its fluid." He remarks in another place that motion when the result of elasticity is quick and sud- den, and ceases as abruptly as it has been pro- duced; but the motions which result from contractility of tissue are slow and impercep- tible, lasting frequently for hours and even days, as are seen in the retraction of muscles after amputation. The distinction laid down in these passages appears to us totally un- supported : to say, for example, that even in a dead artery there are two principles of con- traction which, though their mode of action is literally the same, should nevertheless be con- sidered distinct and referred to different sources appears contrary to every rule of philosophic reasoning. As to the distinction drawn from the comparative quickness of these motions, it is only necessary to say that upon this view of the subject even the movement of the watch-spring itself cannot be attributed to elas- ticity. We must then conclude that there are two and only two forces to which all the various movements of living bodies can be referred ; the one a vital force regulated by its own proper laws, the other a general physical property, whose mode of action is essentially the same in organized and unorganized bodies : the phenomena above enumerated by Bichat 58 ELASTICITY. are certainly not the result of vital action (for he admits that the contractility of tissue to which he ascribes them is not destroyed by death) : they must then be owing to a physical force, and amongst the various physical agen- cies we are acquainted with, elasticity is the only one to which they can be referred. The " vis tnortua" of Haller appears like- wise to differ little if at all from elasticity. Speaking of this force he observes, that, as indeed the very name implies, it is totally in- dependent of life, and adds — " Haec vis in partibus animalium perpetuo agere videtur, etiamsi non perpetuus effectus adparet. Vi- detur enim contractio cuique particulae propria a contraria contractione duorum elementorum vicinorum impugnari et distrahi, ut qua? breviores fieri non possunt, quin mediam par- ticulam distrahant. Id dum fit in omnibus, quies videtur, quae est summa virium contra- riarum se destruentium. Quam primum vero aliqua particula a sodalibus separatur, inflicto vulnere, tunc utique labium vulneris, nunc liberum, nec a contraria potestate retentum, se ad earn vicinam, a qua trahitur, integramque incisa? membranae partem retrahit." The facts so accurately described in this passage are easily explained by the operation of elasticity. Why then multiply causes ? Why assume the existence of another principle in order to ac- count for them ? The phenomena ascribed by Cullen and others to what he terms " tonicity," are also, at least in many instances, the effects of the same physical force. (See Contrac- tility.) II. The tissues of the animal body are pos- sessed of very various degrees of elasticity; some of them are but little inferior to the most highly elastic unorganized substances, while others are endowed with this property in so very trifling a degree, that in our physiological and pathological reasonings concerning them, we may almost consider it as absent. We shall endeavour to arrange the principal organic tissues in the order of their elasticity, and shall then proceed to offer a few remarks upon each. 1. Yellow fibrous tissue. 2. Cartilage. 3. Fibro-cartilage. 4. Skin. 5. Cellular mem- brane. 6. Muscle. 7. Bone. 8. Mucous membrane. 9. Serous membrane. 10. Ner- vous matter. 11. Fibrous membrane. This view of the comparative elasticity of the different tissues must not be regarded as rigorously exact : owing to the impossibility of procuring each one perfectly separate from the others, the result of our experiments can be considered merely as approximate. 1. The yellow fibrous system. — The tissues composing this system are unquestionably the most highly elastic of all : the ligamenta sub- flava which unite the laminae of the vertebrae to one another, and the ligamentum nuchas which suspends the head in some of the larger quadrupeds, are scarcely inferior to caoutchouc in this respect. The middle coat of arteries is referred by Beclard to the yellow fibrous system, perhaps from its possessing in so high a degree this characteristic property. Its exis- tence may be demonstrated by various experi- ments, and many of the physiological and pathological phenomena of the arterial tissue are modified or determined by its presence. The sudden expansion of an artery whether in the living or dead body upon the removal of a force pressing its sides together ; the gradual contraction of a divided artery, by means of which hemorrhage is so frequently arrested ; the contraction or obliteration of the vessel beyond the ligature, after it has been taken up in aneurism ; the obliteration of the umbilical arteries and of the ductus arteriosus soon after birth ; the gaping which occurs in longitudinal wounds of arteries owing to the recession of the divided edges; the power possessed by these vessels of accommodating their size to the quantity of circulating blood, (thus causing endless variations in the volume of the pulse even in the same individual) ; — all these facts have been accounted for by the transverse elasticity of the middle coat. The effects of this property in a longitudinal direction may be seen in the retraction of divided arteries during amputation ; in the sort of locomotion which these vessels undergo from the impulse of the blood, and in the enlargement of a transverse arterial wound by the retraction of its edges. The proper coat of veins, though belonging likewise to this system, is however much less elastic than that of the arteries ; but we cannot agree with those who deny this property to the venous tissue. The sudden flow of blood from a portion of vein included between two ligatures ; the constantly varying size of the cutaneous veins according to the volume of their contents ; the obliteration under certain circumstances of veins where circulation has been arrested, appear to us explicable only by attributing this property to them. 2. Cartilage is possessed of very great elas- ticity. On pressing the point of a scalpel into cartilage it is expelled upon the suspension of the force by the contraction of the sur- rounding substance. It may also be well de- monstrated by twisting or bending the carti- lages of the ribs, or those of the nose, eyelid, &c. The elasticity of cartilage in the adult is much greater than in the child or old person. We shall allude presently to the several impor- tant objects to which this property as connected with cartilage is applied. 3. Fibro-cartilage. — The elasticity of this tissue may be studied in the intervertebral fibro-cartilages, in which it contributes so remarkably to the obscure movements of the spinal column and to the security of the chord : it is remarkably displayed in restoring the sub- stance to its proper condition, when pressure rather than twisting or bending has been the cause of derangement. The fibro-cartilaginous funnels through which the tendons are trans- mitted, possess likewise this property to a great extent. Bichat found, on removing a tendon in a living dog, that the funnel through which it had been transmitted became impervious, like an artery under similar circumstances. ELASTICITY. 59 4. Skin. — The great elasticity of the cuta- neous tissue is exhibited in innumerable in- stances; the extension which it undergoes in pregnancy, in ascites, in cases of large fatty and other tumours, and the promptitude with which in these instances it returns to its proper state after the removal of the distending causes, are matters of every day observation, and are chiefly owing to its elasticity. The great re- traction of the integuments in amputation depends likewise upon the same principle. There is perhaps no tissue in the body where elasticity is more impaired by advanced age : in the young or adult subject, when, owing to disease or other causes, the subcutaneous adi- pose matter has become suddenly absorbed, the skin, owing to its great elasticity, is ena- bled to contract, and thus accommodate itself to the diminished distention ; while in old age, under the same circumstances, the power of contraction is lost, and hence it hangs in loose folds or wrinkles, so characteristic of that period of life. These remarks are meant to apply chiefly to the true skin or corion. 5. Cellular tisme ranks high among the elastic structures : many of the cases which we have just instanced as proving the elasticity of the cutaneous tissue, indicate likewise its existence in the cellular membrane; anasarca, oedema, and still more emphysema, can occur only in consequence of the distention of those filamentous threads which form the cells ; and as recession occurs immediately upon the re- moval of the distending force, it is plain that elasticity is the principle to which the change must be attributed. We may likewise remark that there is no tissue whose elasticity is so frequently and perhaps so usefully em- ployed as that which we are now considering ; for it is by this property of cellular membrane that the motion of the several muscles is per- mitted and even assisted : thus upon elevating the arm the yielding cellular tissue of the axilla permits the member to be drawn up- wards, and when the arm is again depressed the elasticity of the same tense filaments as- sists in some degree the muscles which bring it down. 6. Muscle. — Elasticity appears to belong to the muscular system in a very high degree ; it is, however, extremely difficult to estimate its extent in the muscular fibre itself, partly owing to its being the seat of two other contractile forces, the vis insita and vis nervea, and partly to the great quantity of cellular and other tis- sues which enter into the structure of muscle, and thus impart to it their physical properties. There are however many instances in which we must concede elasticity to the muscular fibre ; the contraction which occurs in the abdominal muscles even long after death, upon removing the accumulation of air or fluid contained within the peritoneum; and the recession of the cut edges which takes place upon dividing a muscle under the same circumstances, cannot be ascribed either to the vis nervea or to the vis insita, (for they have ceased to exist,) and the contraction is evidently too extensive to be attributed wholly to the cellular tissue. But we may observe the operation of this property even in the living muscles : on dividing the facial muscles of one side in a living animal the mouth is gradually drawn towards the opposite, and this takes place not by the effort, but solely by the elasticity of the un- injured muscles, which have now no coun- teracting force upon the other side to resist their contraction. So it is with all the other muscles during what is called their state of rest : the elasticity of one class is exactly ba- lanced by the same property in their antago- nists; and hence when the influence of the will is completely withdrawn, as in sleep, we may estimate the comparative quantity of elas- ticity which antagonizing muscles are possessed of : those of the face for example are exactly equal upon opposite sides in this respect, and accordingly the mouth retains its proper central position ; but in the limbs, as the elasticity of the flexors exceeds that of the extensors, we usually find these parts of the body during sleep in a semiflexed position. 7. Bone possesses considerable elasticity, though its degree is frequently underrated by the superficial observer. It is not easily demon- strable in the larger bones, but upon cutting even these into thin plates its existence becomes at once evident. There are many phenomena both healthy and diseased which depend upon the elasticity of bone ; the enlargement of the maxillary sinus from the growth of fungus within its cavity, and the collapse of its walls upon the removal of the distending matter; the obliteration of the alveolus after the extraction of a tooth ; the narrowing of the optic hole which is found in cases of atrophy of the optic nerves, and of the carotid canal after tying the carotid artery ; the diminution of the orbital cavity which gradually takes place upon extir- pation of the eye — all these changes depend in a great degree upon the elastic qualities of bone. The great elasticity of the osseous system in the young subject, and the almost entire absence of it in the bones of old persons, is at once ex- plained by the fact that elasticity resides in the cartilaginous and not in the earthy ingredient ; the great proportion of the former in the young bone, and the accumulating deposition of earthy matter as age advances, are known to every observer. 8. Mucous membrane. — That this tissue is possessed of some degree of elasticity would appear from the well-known contraction which is found in the lower part of the intestinal canal after the establishment of an artificial anus; from the great variation of size which is observed in the stomach, and by means of which it can accomodate itself to the quantity of food con- tained within it; and from many other simi- lar instances. But in these cases it is often difficult to determine how far contraction de- pends upon the mucous membrane, or upon the other tissues with which it is associated. We should also bear in mind that the contraction of the inner coat of the stomach is much less than might in the first instance be supposed ; 60 ELASTICITY. the numerous folds or rugee into which it is thrown seem destined to compensate for its im- perfect elasticity. 9. Serous membrane is still lower in the scale. In those organs whose size is subjected to frequent variation, such as the stomach, in- testines, urinary bladder, &c, we find an inter- esting provision to permit enlargement without at all stretching their serous envelope. The organ, instead of possessing a simple serous capsule, is inserted between two loosely adher- ent folds of peritoneum which permit its insinu- ation between them as soon as distension takes place. By this simple contrivance the possibi- lity of rupture or even tension of the serous coat is completely obviated, even in cases of extreme enlargement. The tunica vaginalis testis would appear to possess more elasticity than other membranes of this class : — after the ope- ration for hydrocele, a disease in which it is distended far beyond its proper limits, a sudden contraction of its tissue evidently occurs. 10. Nervous matter. — Upon the division of a nerve little or no retraction of the divided ex- tremities takes place. The brain however possesses an obscure elasticity, as may be seen upon making a horizontal section of its sub- stance : the numerous red points which there present themselves are owing to the blood forced from the divided vessels by the surrounding pressure. 11. Fibrous membrane is remarkable for its very low degree of elasticity; hence liga- ments and tendons often give way rather than yield to a distending force. It is owing to the unyielding nature of the subcutaneous fascia in some situations that abscesses and other swel- lings occurring beneath, produce but little swel- ling upon the surface, and cause such severe pain to the patient; hence too upon dividing this fascia, no enlargement of the wound occurs as in other tissues by the elastic retraction of its edges. When the distending force however is slowly applied, there appears to exist some degree of" elasticity even in fibrous membranes ; thus in hydrops articuli the structures about the joint are frequently much distended by the ac- cumulation of fluid within, upon the absorption of which they slowly resume their proper con- dition. III. We shall now proceed to point out some instances in which elasticity plays an im- portant part in the mechanism of organized beings ; but it may be necessary to remark that in doing so we by no means profess to give an anatomical description of the various structures alluded to. We shall endeavour merely to bring into one general view some of the most inter- esting cases in which elasticity plays a prominent part, and thus enable the reader to refer to the separate articles in which these details are fully discussed. Nature avails herself of this physical property in the construction of organized bodies, for several distinct ends. It is sometimes employed as a means of protecting certain delicate and important organs by bearing off or decomposing the forces to which they are exposed. It is often used to economise muscular contraction, not only in supporting depending parts, but likewise in effecting the movement of one por- tion of the body upon another. In some instan- ces it is rendered subservient to the general movement of the body, or locomotion. By elas- ticity the proper patulous condition of certain canals and outlets is secured ; and lastly, it very often serves to divide the power of particular muscles or sets of muscles, and thus to transfer the contractile force from one portion of an ap- paratus to another. 1. Elasticity is employed by nature as a means of protecting the body generally, or some of its organs more particularly, against external violence. The great elasticity of the various tissues in the young subject, and of the osseous system especially, affords at that period of life no inconsiderable security to the whole system : the bones themselves can yield in a very great degree to external impressions and thus prevent their bad effects. The frequent and apparently dangerous falls of children, and the perfect im- punity with which they are encountered, are known to every one, and can easily be accounted for by the great elasticity of the tissues at that period of life. The opposite extreme of human existence, in which we meet with the reverse of these conditions, is equally illustrative of our subject ; for then the bones, owing to the pro- gressive accumulation of earthy matter, have al- most lost their power of yielding, and hence a very slight force is sufficient to fracture them. But elasticity plays a still more important part in protecting certain organs, such as the spinal chord, whose structure is so delicate that it may be torn by the slightest violence, and whose func- tion is frequently deranged even by mere con- cussion. The mechanism of the vertebral column exhibits at every step the most admirable appli- cation of elasticity to the protection of its con- tents. An unskilful mechanic who sought to afford the greatest security to this contained or- gan might naturally enough suppose that its safety would be proportionate to the strength and density of the material which he should employ in incasing it ; he would probably have thrown around it a strong cylinder of solid bone, such as we see employed for a different object in the tibia or femur. But the condition of old age again affords us a complete refutation of such reasonings ; the spinal column by the successive consolidation of its component parts is then in fact converted into one long cylinder of extraordinary strength ; it has become literally a single bone ; but now every touch upon the surface of the body, every application of the foot upon the ground, is conveyed by the solid and almost inelastic bones to the spinal cord, thus rendering even the movements of progression a source of pain ; hence repose is the natural con- dition of this period of life, as restless activity is that of childhood. But looking at the spinal column in the active or adult age we perceive a totally different mechanism ; it now consists of no less than twenty-four distinct bones piled one upon the other and connected by twenty-four layers of fibro-cartilage, a tissue, as we have al- ELASTICITY. 61 ready seen, possessed of extraordinary elasticity. The chord, instead of filling the whole cavity, is suspended within it by means of an elastic liga- ment; and thus this delicate cylinder of nervous matter is hung loosely upon a series of elastic springs which effectually break the many jolts and concussions incident to the frame in the various movements of active life. It is owing to this extreme elasticity of the spinal column, that even after very long-continued pressure, it soon recovers its proper condition. When, for instance, from long and severe exercise the fibro- cartilages have become somewhat pressed down by the superincumbent weight, a few hours' repose in the horizontal position is sufficient to restore the spine to its proper length. This fact has not escaped the shrewd practical observa- tion of the lower classes ; when admission into the army can be obtained only by persons of a certain stature, the candidate who apprehends he can spare nothing in that particular, usually presents himself after his night's repose. The delicate viscera of the thoracic cavity owe like- wise their safety in a great degree to the same me- chanism. The cartilages which connect the ribs and sternum, and which, as we shall presently find, are destined to modify the movements of the thorax, tend likewise to its security by per- mitting it to yield to external forces. The ob- scure elasticity of the ribs themselves and of the ligaments connecting them to the spine contri- bute to the same end ; hence we seldom find the thoracic viscera ruptured even by the greatest violence applied against their walls. It is this elasticity, aided no doubt by other still more efficient causes, which enables the mountebank to receive with impunity the blows of the weightiest sledge on an anvil laid upon his chest. 2. Elasticity is often had recourse to as a substitute for muscular contraction, and, as it would appear, with a view to economize that more important property. We find, for ex- ample, that in most animals the abdominal viscera are supported in their position chiefly by the muscles of the abdomen, and that on being forced downwards in inspiration by the descent of the diaphragm, they are again pressed upwards by the contraction of these muscles. In the large ruminating quadrupeds whose abdominal viscera are of so great a size, and in whom, owing to the horizontal position of the trunk, these organs tend directly down- wards, the quantity of muscular power requi- site to support and move them should neces- sarily have been of great amount ; but instead of increasing the quantity of muscle to such an extent, nature has effected her purposes by much more simple means. Beneath the abdominal integuments there exists a mem- brane of great strength and elasticity, which not only supports the viscera but also helps to elevate them after they have been forced downwards in inspiration. The elastic liga- mentum nucha, which in these animals sup- ports the very weighty head, is a simple but complete substitute for the great mass of muscle which should have existed on the back part of the neck, in order to effect the same end. So obviously in this instance is elasticity a substitute for muscularity, that upon com- paring the structure in various animals we find the strength and elasticity of the ligament always proportionate to the weight of the head which it has to support. In the carnivora an interesting application of this property is seen in the retractile ligament passing between the claw and the phalangeal bone ; as the claw in many genera is the chief weapon of attack, it must not be suffered to come into contact with the ground in progression, for otherwise it would become blunted, as seen in those which do not use it for the purposes mentioned; it is consequently suspended by the retractile liga- ment until drawn down at the will of the animal by means of the flexor muscles. Elasticity is here used as the means of suspension in order to save the effort of a constant muscular exer- tion. In the mollusea we see this property again employed to economize muscularity : the shell of the oyster admits of being opened as well as closed at the will of the animal ; but muscularity is the source of the one ac- tion; elasticity residing in a strong ligament is the means of effecting the other. 3. Elasticity frequently preserves the patu- lous condition of certain outlets in the animal body, as, for example, those of the eyes and nostrils. This object is attained by the inser- tion of a rim of highly elastic cartilage into the soft parts which bound these openings. A material of greater rigidity, such as bone, would, it may be objected, have answered the purpose still better: but the rigidity of that substance would have greatly interfered with the free movements necessary for the functions of the lids, and in the nose would not only have increased the risk of injury from external violence, but would have prevented the ap- proximation of the alse which must take place in order to expel the nasal mucus. Neither would a soft and inelastic material have an- swered the purpose, for then the first effect of inspiration would be to approximate the edges of the opening, and thus to prevent the further entrance of air. The tracheal and bronchial canals are likewise preserved patulous by the same elastic material ; and we again meet with it performing a like office in the Eustachian tube and the external meatus of the ear. 4. Elasticity is sometimes rendered subser- vient to locomotion, or the general movement of the body. The elastic pad placed beneath the foot of the dromedary and many other ani- mals is no doubt intended to facilitate progres- sion, and to compensate in some degree for the yielding looseness of the sands upon which they tread. The same apparatus is found in very great perfection in the feet of the carni- vora, and must be of great use in enabling them to make those enormous bounds by which they spring upon their prey. But perhaps one of the most interesting examples of elasticity being rendered subservient to locomotion is met with in certain fish. The salmon, during its annual ascent to fresh-water streams for the 62 REGION OF THE ELBOW. purpose of depositing its spawn, often encoun- ters cataracts of great height, and which would seem to render farther progress impos- sible. By means, however, of a powerfully muscular tail and elastic spine it is enabled to surmount those obstacles ; resting one side upon a solid fulcrum, it seizes its tail between its teeth, and thus draws itself into an arch of amazing tension ; then suddenly letting go its hold, and thus freeing the elastic spring which its body represented, it is thrown into the air, often, as Twiss has seen in Ballyshannon in Ireland, to a height of twelve or fifteen feet, and falls beyond the obstacle which had op- posed it. 5. Elasticity becomes occasionally in the animal machine a means of dividing muscular force, and thus transferring it from one portion of an apparatus to another. The muscles of inspiration are, if we may use the word, too strong for their opponents, and hence it be- comes necessary to transfer a portion of their superfluous strength to the weaker set. This is effected by means of the elastic cartilages which connect the ribs and sternum. The in- spiratory muscles in enlarging the thorax act with such a force that they not only elevate the ribs, but even stretch and twist the cartilages, and hence no sooner is inspiration completed than elasticity conies into play, tending to depress the ribs and thus to assist the weaker muscles. But we must not fall into the error of suppo- sing that elasticity is in this case a substitute for muscularity, and much less that it is in itself a source of power. The only power exercised by it is that which it has just bor- rowed from the inspiratory muscles : had not the elasticity of the cartilages been set in action by this external agency, it would, like the elas- ticity of the watch-spring under the same cir- cumstances, have remained for ever dormant. In those interesting discussions which have arisen of late years relative to what is termed the suction power of the heart, we apprehend that much error has arisen from overlooking this simple law of elasticity. That doctine will of course be fully stated and examined in its proper place ; at present we shall merely observe that it was first regularly put forward in the admirable work of Dr. Wilson Philip, that it was followed up and explained by Dr. Carson, and that these views were regarded by Laennec with such respect that he pronounces their discovery the most important step made in this department of physiology since the time of Harvey. The heart, it is said, is not merely a forcing pump which by the contrac- tion of its ventricle propels the blood through- out the arteries ; it is likewise a suction pump, for by the expansion of the auricles it draws in the blood from the veins. Now this expansive force, if indeed it exist at all, is, we are quite satisfied, merely the effect of the heart's elas- ticity; for the reasonings of those who attempt to prove it of a specific nature are evidently insufficient. In this point of view the heart's expansion cannot be regarded as a new and independent power; if that organ be really elastic, then the muscular force of its systole must be greater than it would otherwise have been, for it has not only to propel the blood through the arterial system, but likewise to overcome the resisting elasticity of its own structure: this suction power of the heart is then merely the recoil of the surplus force ; what is gained upon the one hand is lost upon the other ; and hence elasticity in this instance cannot be regarded as an independent prin- ciple contributing to the blood's motion, but merely as a means of dividing muscular power and transferring a portion of it from the begin- ning of the arterial to the end of the venous system. 6. An interesting application of elasticity in the animal machine is to convert an occasional or intermitting force into a continued one. As human ingenuity has long since discovered the application of this principle, we may see it employed in many mechanical contrivances. In the common fire-engine, for instance, we observe that though it is worked by interrupted jerks, yet the water issues from its pipe, not per saltum as we should have expected, but in one uniform and continued stream. This is effected by causing the fluid to pass, in the first instance, into a hermetically sealed vessel con- taining a portion of atmospheric air : the accu- mulation of the water presses the air into a smaller space, but in doing so it is reacted upon by the elasticity of that gas, which may thus be considered as a powerfully elastic spring exerting upon the surface of the water an uniform and continual pressure. The very same principle is employed in the mechanism of the arterial system. Upon opening one of the small arteries we perceive that the blood does not flow per saltum as in those which are nearer to the heart, but issues in an uniform and uninterrupted stream. The intermitting action of the heart has in fact been converted into a continued one by means of the elasticity of the arterial tissue. We might indeed say with truth that the blood in these small arteries is not directly propelled by the heart at all; the force of that organ is expended in distend- ing the larger elastic arteries, as the force in the fire-engine is expended in compressing the air. The immediate cause of motion is in the one case the reaction of the elastic air, and in the other the reaction of the elactic artery. For the Bibliography of this article, see that of Fibrous Tissue and Muscle. ( Joint E. Bretian.) ELBOW, REGION OF THE ; fold or bend of the arm. (Fr. plidubras; coude.) The region of the elbow is situated at the angular union of the arm with the fore-arm, and con- tains the humero-cubital articulation and the various organs which surround it : the extent of this region may be determined, superiorly by a circular line at a finger's breadth above the internal condyle, and inferiorly by a similar line at two fingers' breadth below that process : its greatest extent is in the transverse direction, and it forms an angle salient posteriorly and TtEGION OF THE ELBOW. 63 retiring in front, which cannot be effaced even in the utmost extension of the fore-arm. The ' anterior surface of this region when examined in the arm of a muscular man presents a triangular depression, in which is observed the confluence of several large subcutaneous veins ; the base of this depression is above ; the sides are formed by two prominences, of which the ex- ternal is larger and more marked than the in- ternal, and the apex of the triangle is formed inferiorly by the convergence of these pro- minences, which consist of the two masses of the muscles of the fore-arm which arise from the condyles of the humerus. This triangular depression is divided superiorly into two por- tions by a prominence formed by the tendon of the biceps ; in the external or larger portion the median cephalic vein is situated, the in- ternal is occupied by the oblique course of the median basilic vein and the trunk of the brachial artery, the pulsations of which can usually be felt and are even sometimes visible in this space : the superficial radial or cephalic vein and the two ulnar veins which contribute to form the basilic are also apparent in this region, being situated over the lateral mus- cular prominences. In the arm of a corpulent female, instead of the appearances here de- scribed, the front of the elbow presents a semilunar fold or depression, the concavity of which embraces the prominence formed by the biceps. Laterally, the region of the elbow presents two prominences formed by the condyles of the humerus, of which the internal is more marked and higher than the external : in the arms of corpulent persons, on the contrary, two depressions like dimples are placed over the condyles. Posteriorly, the olecranon forms a remark- able prominence, the situation of which varies in its relation to the condyles of the humerus according to the different motions of the fore- arm ; in complete extension it is above the level of these processes, in semiflexion it is on the same level with them, and is below them when the elbow is flexed to a right angle. On either side of the olecranon there is a depression of which that on the internal side is more marked ; pressure here produces a painful sensation which is felt in the little ringer and the inner side of the ring-finger; in the depression external to the olecranon the posterior edge of the head of the radius can be felt rotating immediately below the external condyle when pronation and supination of the fore-arm are performed. An accurate know- ledge of the relations of these parts is essential to the forming an accurate diagnosis in cases of fractures and dislocations in this region. Skin and subcutaneous tissue. — The skin covering this region is thin, smooth, and de- licate in front ; it is furnished with hairs over the lateral prominences, where it also contains sebaceous follicles in greater numbers than over the anterior depression. In consequence of being very vascular and plentifully supplied with nerves, the skin here is prone to inflam- mation, and is often the seat of small phlegmo- nous abscesses and of erysipelas. Posteriorly the skin is thicker, rough on the surface, and generally thrown into transverse folds above the olecranon, particularly in extension : it abounds more in sebaceous follicles and hairs here than on the anterior surface. The sub- cutaneous cellular tissue in front consists of two layers : one of these, more deep-seated, forms a sort of fascia, between the layers of which the subcutaneous veins and nerves are situated ; the other, superficial, is principally composed of adipose tissue and varies very much in thickness. In lean persons this latter layer is often of extreme tenuity ; while the other, on the contrary, is then thicker and more closely adherent to the skin. This deeper layer is considerably thicker over the anterior angular depression than on the lateral pro- minences : it sinks in between the pronator radii teres and supinator longus in company with the deep median vein, and is continuous with the cellular tissue between the muscles and around the articulation. Posteriorly the subcutaneous cellular membrane is more loose and lamellar : adipose tissue is almost always absent in it over the condyles of the humerus, and on the smooth posterior surface of the olecranon, there is merely a subcutaneous bursa mucosa between the skin and the peri- osteum. The subcutaneous cellular tissue in front of the elbow contains some large veins, besides lymphatics and filaments of cutaneous nerves. As the subcutaneous veins in this region are those most frequently selected by surgeons for the operation of phlebotomy, and as un- toward consequences sometimes result from a want of due care or of sufficient anatomical knowledge on the part of the operator, their situation and connexions should be carefully studied. These veins are subject to much variety in their size, number, and situation: the following arrangement of them is that most uniformly adopted by authors as the normal one : three principal veins coming from the fore-aim enter the lower part of this region: 1st, the radial or cephalic on the external side courses along the external muscular prominence and ascends to the arm on the external side of the biceps ; 2d, the ulnar or basilic ascends over the in- ternal muscular prominence and the internal condyle of the humerus to the inner side of the biceps; 3d, the median vein ascending from the front of the fore-arm enters the apex of the triangular depression of the elbow, at which point it is usually augmented by a deep branch coming from the deep radial and ulnar veins, and immediately divides at an acute angle into two branches, one of which ascends on each side of the biceps ; the internal of these, called median basilic, runs obliquely upwards and inwards over the course of the brachial artery, and joins the basilic vein above the internal condyle ; its lower extremity is external to the brachial artery, which it crosses obliquely so as to get internal to it superiorly : 84 REGION -OF THE ELBOW. the other division of the median vein, called median cephalic, passes obliquely upwards and outwards, external to the prominence formed by the biceps, and joins the cephalic at an acute angle above the external condyle. The cephalic, the basilic, and the two divi- sions of the median vein joining them, form a figure which somewhat resembles the Roman capital letter M. The superficial lymphatic vessels follow the course of the veins ; those on the internal side are larger and enter small ganglions, varying in number from two to five, which are situated in the subcutaneous cellular tissue, above and in front of the internal condyle, where they are sometimes seen swollen and inflamed in consequence of inflammatory affections of the hand or fore- arm. The subcutaneous nerves are : branches of the internal cutaneous, usually three or four in number, the external cutaneous, and some twigs from the radial and ulnar nerves. The branches of the internal cutaneous pass down to the fore-arm, generally superficial to the basilic and median basilic veins, while the external cutaneous lies deeper than the ce- phalic and median cephalic, with the latter of which it is more intimately connected. Some twigs from both the internal and the external cutaneous nerves are distributed to the inte- guments behind the elbow. Aponeurosis. — The aponeurosis of the region of the elbow is continuous with the brachial aponeurosis above, and with that of the fore- arm inferiorly ; it is strong behind the elbow, where it receives an expansion from the tendon of the triceps, and has an intimate adhesion to the margin of the olecranon : on each side it is firmly attached to the condyles of the hu- merus, sending off several layers from its internal surface, which form septa between the origins of the muscles of the fore-arm which arise from these processes : anteriorly it is spread over the triangular depression, where its strength is considerably increased by ex- pansions which it receives from the tendons of the biceps and the brachials amicus ; the ex- pansion from the brachiaeus anticus comes forward on the external side of the tendon of the biceps, and is lost over the external mus- cular prominence of the fore-arm in front of the external condyle ; the expansion from the biceps forms a narrow band about half an inch in breadth where it is first detached from the tendon of that muscle ; it then descends obliquely to the inner side of the fore-arm, on the aponeurosis of which it is lost about two inches below the inner condyle. Superiorly this expansion crosses over the brachial artery, and its superior margin is defined by a lunated border to which the brachial aponeurosis is attached, while its inferior margin is con- founded with the aponeurosis of the fore- arm. From the above described attachments of the tendons of the biceps and brachiaeus an- ticus to the aponeurosis of this region, it fol- lows as a necessary consequence that the con- tractions of these muscles must have the effect of rendering it more tense. The aponeurosis of the arm assumes the form of a very thin fascia as it approaches the superior margin of the expansion of the biceps ; at this place it often appears to degenerate into cellular tissue which covers an oval space placed obliquely, the broader extremity of which is below, being bounded by the expan- sion of the biceps externally and inferiorly, and by a sort of defined border terminating the lower margin of the brachial aponeurosis superiorly and internally : in this oval space the brachial artery and the median nerve which lies to its inner side are more thinly covered than in any other part of their course. The aponeurosis is also very weak on the external side of the expansion of the biceps, where it is pierced by the deep branch of the median vein, and by the external cutaneous nerve which comes from beneath the aponeurosis at this place. The brachial artery terminates by dividing into the radial and ulnar arteries in the tri- angular depression, which is bounded exter- nally by the supinator longus and internally by the pronator radii teres. This artery enters the region of the elbow on the internal side of the tendon of the biceps included in a common sheath with its two venae comites, one of which lies on either side of it ; it lies on the surface of the brachiaeus anticus, and, becoming deeper as it descends, it divides into the radial and ulnar arteries at about an inch below the level of the internal condyle. The median nerve lies internal to it, separated from it at first by cellular tissue ; lower down, where this nerve pierces the pro- nator teres, the external origin of that muscle arising from the coronoid process is interposed between it and the artery : the radial and ulnar arteries, while still in this region, give off their recurrent branches, which pass upwards, encir- cling the condyles of the humerus, to anasto- mose with the profundae and anastomotic branches of the brachial, as described in the article Brachial Artery. The venae comites of the brachial, radial, and ulnar arteries are double : these vessels are also accompanied by a deep set of lymphatics. The nerves which traverse this region beneath the aponeurosis are, the median on the internal side of the brachial artery ; the radial, which, descending between the brachiaeus anticus and the supinator radii longus, then between the biceps and ex- tensor carpi radialis, divides into two branches, the posterior of which passes between the supi- nator brevis and extensor carpi radialis brevior to the muscles on the back part of the fore-arm, while the anterior branch or proper radial nerve descends in the fore-arm under the su- pinator radii longus. The trunk of the ulnar nerve passes behind the internal condyle, and entering between the two heads of the flexor carpi ulnaris follows that muscle down the fore-arm. Development. — In early life the condyles of the humerus are not so well marked, nor is ARTICULATION OF THE ELBOW. 65 the olecranon so prominent, in consequence of which extension of the elbow can be carried farther than in the adult. At the same period the lesser sigmoid cavity of the ulna is pro- portionally smaller, and the annular ligament of the radius much more extensive. Varieties. — When a high division of the brachial artery takes place, it often happens that the radial artery takes a superficial course, sometimes under and occasionally over the aponeurosis to its usual destination. The pos- sibility of this occurrence should be constantly held in recollection in performing phlebotomy in this region, as it is evident that the vessel, when thus superficially situated, is exposed to be wounded by the lancet of the operator. In considering the relative advantages pre- sented by each of the superficial veins which may be selected for phlebotomy, it is necessary to remark that the operation may be performed on any of the veins at the bend of the arm ; on the cephalic and basilic veins it is un- attended with any danger; not so, however, when either the median basilic or median cephalic is the vessel selected. When bleed- ing in the median basilic vein about the mid- dle of its course, if the lancet should transfix the vein, there is danger of the instrument wounding the brachial artery, an accident of serious consequence ; the risk of this accident is not so great when the vein is opened near its lower part, as the brachial artery retires from it here towards the bottom of the trian- gular depression of the elbow ; besides the occasional risk of wounding the radial artery, which, in consequence of a high bifurcation of the brachial, sometimes follows the super- ficial course already alluded to, the branches of the internal cutaneous nerve may be wholly or partially divided ; in which latter case sharp pains are usually felt extending along the course of these nerves. Opening the median cephalic vein may be performed without ap- prehension of injury to the brachial artery; the external cutaneous nerve however, the trunk of which lies behind this vein, may suffer a puncture, in consequence of the lancet being pushed too deeply, the consequences follow- ing which have been in many instances a pain- ful affection extending along the branches of this nerve to their terminations. In those un- fortunate cases in which the brachial artery is punctured, should the wound in the artery not be closed and united by properly regulated pressure, the consequence likely to ensue may be one of the following: 1, the blood escap- ing from the wound in the artery may become diffused through the cellular membrane of the limb extending principally upwards towards the axilla along the sheath of the vessel, ( the diffused false aneurism ;) 2, the blood which escapes from the artery may be circumscribed within a limited space by the cellular mem- brane which surrounds it becoming condensed, (the circumscribed false aneurism ;) 3, the wounded orifices of the artery and vein may remain in apposition, and adhere to each other, allowing the blood to pass from the artery VOL. II. directly into the vein, constituting the affection called aneurismal varix ; 4, or a circum- scribed sac may be formed between the artery and vein, having a communication with both vessels, the varicose aneurism. (J. Hart.) ELBOW (ARTICULATION OF THE), ayxcov, cubitus ; Fr. coude ; Germ, elbogen ; Ital. gomito. The elbow or humero-cubital articulation is an angular ginglymus formed by the inferior articular extremity of the os humeri and the superior articular extremities of the radius and ulna, the surfaces of which are, in. the recent state, covered with a cartilaginous incrustation, and kept in apposition by an ex- tensive synovial capsule, an anterior, a poste- rior, and two strong lateral ligaments. The muscles which cover this articulation are, the brachiaeus anticus, the inferior tendon of the triceps, and some of the muscles of the fore-arm anteriorly, the triceps and anconasus posteriorly, and the superior attachments of several of the muscles of the fore-arm laterally. Bones. — The lower part of the humerus is flattened before and behind, and curved a little forwards : an obtuse longitudinal ridge, on a line corresponding to the lesser tuberosity at its superior extremity, divides it into two slo- ping surfaces anteriorly, while posteriorly it presents a broad, flat, triangular surface : a sharp ridge on each side terminates below in a rough tuberosity, called a condyle ; the exter- nal condyle is the smaller of the two, and when the arm hangs loosely by the side, it is directed outwards and forwards : the internal condyle is much larger, more prominent, and directed inwards and backwards : a line let fall per- pendicularly from the most prominent part of the greater tuberosity above would fall upon the external condyle ; the internal condyle bears a similar relation to the centre of the superior articular head of the humerus. The inferior articular surface extends transversely, below and between the condyles, and presents a series of eminences and depressions ; begin- ning at the external side, a small spheroidal eminence, the eminentia capitata or lesser head, situated on the front of the external condyle, directed forwards and received into the circular cavity on the head of the radius, internal to this is a small grooved depression which lodges the internal part of the border of that cavity: the remainder of this surface forms a sort of pulley, to which the greater sigmoid cavity of the ulna corresponds; this, which is called the trochlea, presents a large depression placed be- tween two raised ridges : the depressed portion of the trochlea winds round the lower extre- mity of the humerus in an oblique direction from before backwards and a little outwards, being broader behind than in front ; its external border forms a semicircular ridge, smooth in front and sharp behind, the anterior part of which corresponds to the division between the radius and ulna; its internal margin also forms a semicircular ridge, sharper and more promi- nent than the external, and which projects half CO ARTICULATION OF THE ELBOW. an inch below the internal condyle, having be- tween it and this latter process a sinuosity in which the ulnar nerve lies ; it is the prominence of this ridge which determines the obliquity in the direction of the humerus, observable when its inferior articular extremity is placed on a horizontal surface. Behind and above the trochlea a large trian- gular depression (fossa posterior ) receives the olecranon in extension of the fore-arm ; a simi- lar depression of smaller size (fossa anterior) receives the coronoid process in flexion ; these two fossae are separated by a plate of bone, often so thin as to be diaphanous, and some- times they communicate by an aperture, the longest diameter of which is transverse, as in the quadrumana, carnivora, glires, and pachy- dermata ; Meckel is of opinion that the exist- ence of this aperture in the human subject is more frequent in the Negro and Papuas than in the Caucasian race ;* however it did not exist in any one of three Negroes and four Mulattoes which I dissected, while I possess two specimens of it, and have seen several others which occurred in Europeans : a second small fossa frequently exists above in front of the eminentia capitata, into which the head of the radius is received in complete flexion. The superior extremity of the ulna presents anteriorly a deep cavity, ( the greater sigmoid cavity,) which is concave from above down- wards and convex in the transverse direction : it is bounded behind by the olecranon and in front by the coronoid process ; the surface of this cavity is smooth and covered by cartilage, with the exception of a rough transverse notch which extends from the internal side nearly the whole way across it, and the inequalities of which are effaced in the recent state by a cushion of soft adipose tissue : on the external side of the coronoid process there is a small smooth lateral surface, oval in shape, ( the lesser sigmoid cavity,) which is concave from before backwards ; this depression is covered by an extension of the cartilage of the greater sigmoid cavity, and receives the internal side of the head of the radius. The superior extremity of the radius forms a shallow circular depression which receives the lesser head of the humerus; this surface is covered by a cartilage which extends over its circumference on a circular surface applied to the lesser sigmoid cavity of the ulna internally, and embraced by the annular ligament in the rest of its extent : the articular head of the radius is supported on a cylindrical portion, called its neck, which is much smaller in its circumference, of about a finger's breadth long and curved a little outwards, its junction with the shaft of the bone being marked internally by a rough tuberosity, the tubercle of the ra- dius, into the posterior side of which the tendon of the triceps is inserted. Ligaments. — The fibrous ligaments of the elbow are four in number; 1st, the anterior * Handbucli der menschlicherf Anatomie, band ii. ligament consists of oblique and perpendicular fibres arising superiorly from the front of the condyles and the part of the humerus imme- diately above the two anterior articular fossse, and is inserted into the anterior edge of the coronoid process of the ulna inferiorly ; 2d, the posterior ligament is less distinct than the an- terior, consisting of transverse fibres extending from one condyle to the other, which become more evident when the elbow is flexed ; 3d, the external lateral ligament arises from the ante- rior surface of the external condyle by a thick cord-like fasciculus of shining silvery fibres, and spreads out into a broad flat expansion, which is inserted into the whole length of the annular ligament of the radius and into the anterior and posterior margins of the lesser sig- moid cavity of the ulna; the tendons of origin of the supinator brevis and extensor muscles of the hand are intimately connected to the exter- nal surface of this ligament, but can be easily separated from it by careful dissection ; 4th, the internal lateral ligament arises from the an- terior surface of the internal condyle of the humerus, and passing over the internal side of the synovial capsule, divides into two portions, an anterior and a posterior, the former of which is inserted into the inner side of the coronoid process, and the latter into the internal side of the olecranon : this ligament presents more of a flattened form, and is more easily separated from the tendons of the muscles which cover it than the external lateral ligament. The synovial capsule, having covered the ar- ticular surface of the humerus, ascends above this surface as high as an irregular continuous line, including the two anterior articular fossog in front, the posterior articular fossa behind, and limited by the bases of the condyles late- rally ; at the level of this line the capsule is re- flected from the humerus, and descends on the internal surfaces of the fibrous ligaments to be expanded over the articular surfaces of the radius and ulna, to the cartilaginous coverings of which it adheres in the same intimate man- ner as to that of the articular surface of the humerus ; the portion of it corresponding to the radius descends within the annular liga- ment, below which it is reflected on the neck, and thence continued over the head of that bone ; while it becomes attached to the ulna at the line which circumscribes the greater and lesser sigmoid cavities over the surfaces of which it is extended ; this capsule, which is rather tense where it lines the lateral ligaments, is flaccid and sacculated anteriorly and poste- riorly, so as not to interfere with the freedom of flexion and extension of the elbow : below the margin of the annular ligament and before it is attached to the neck of the radius, it forms a cul-de-sac so loose as to permit the rotatory motions of that bone to be executed without restraint. Several masses of adipose cellular tissue are situated around the articulation external to the synovial capsule, more especially in the articu- lar fossae at the posterior margin of the olecra- non : between the radius and ulna and in the ABNORMAL CONDITION OF THE ELBOW-JOINT. 67 notch on the internal side of the greater sigmoid cavity, there always occurs a mass of this sub- stance from which a production extends over the rough groove described above, dividing the sigmoid cavity transversely. The synovial capsule adheres closely to the fibrous ligaments, except where masses of adi- pose tissue are interposed, to which it is but loosely connected. Motions. — The elbow is a joint remarkable for possessing great solidity, which is partly owing to the extent of its osseous surfaces and the manner in which they are locked into each other, and partly to the strong lateral ligaments and the muscles which surround it. The motions enjoyed by the elbow-joint are flexion and extension. Flexion may vary in degree so as to be com- plete or incomplete : in complete flexion the fore-arm is carried forwards and inwards in an oblique direction across the front of the thorax, so as to bring the hand towards the mouth ; the direction of the fore-arm is determined in this movement by the obliquity of the trochlea of the humerus from behind forwards and in- wards, as described above, and influenced by the clavicle preventing the falling inwards of the shoulder; were it not for the support of the clavicle, the hand in this movement, instead of being carried to the mouth, would be direct- ed to the shoulder of the opposite side : when flexion of the elbow is carried to its greatest extent, the coronoid process and the head of the radius are received into the anterior articu- lar fossae of the humerus, displacing the adipose masses from these cavities, the olecranon is brought downwards on the trochlea so as to be placed below the level of the condyles of the humerus ; the posterior part of the synovial capsule, the posterior ligament, and the triceps and anconeus muscles are made tense, and applied to the adipose mass in the posterior articular fossa and to the posterior part of the trochlea : the anterior part of the capsule and the anterior ligament are relaxed, as are also the lateral ligaments. A dislocation is rendered impossible in this state of the articulation, being effectually opposed by the hold which the coronoid process has on the front of the trochlea of the humerus. In partial flexion or semiflexion, the several parts of the articulation are differently circum- stanced ; the coronoid process being carried down is no longer applied to the front of the humerus, the olecranon is on a plane with the condyles, and the lateral ligaments are on the stretch : in this state of the parts a powerful force applied to the olecranon from behind might have the effect of displacing the ulna forwards, were it not for the great mobility of the limb, owing to which a force thus applied is moderated or altogether expended in increa- sing the degree of flexion ; hence a dislocation of the ulna forwards on the humerus is an acci- dent which never happens. In extension, the olecranon, ascending above the level of the condyles, is received into the posterior articular fossa, displacing the adipose substance which previously occupied that fossa, the radius is brought back on the lesser head of the humerus, over the anterior part of which and of the trochlea the capsule and the anterior ligament are stretched; the lateral ligaments, the tendon of the triceps, and the brachials anticus are also in a state of tension : the pos- terior part of the capsule and the posterior ligament are necessarily relaxed. It is when the elbow is in such a state of extension as here described that a dislocation of the fore-arm backwards usually occurs in consequence of a fall on the hand ; the force producing the dis- location in this case operates in the following way, the fore-arm serving as a fixed point, the humerus becomes a lever of the first order, the fulcrum of which is the point of the olecranon applied to the posterior side of its lower extre- mity, the power is represented by the weight of the trunk of the body applied to its superior extremity in front, and acting with a force pro- portioned to its remoteness from the point of resistance formed by the ligaments and muscles which are found in a state of tension in front ; when this force is such as to overcome the re- sistance, the ligaments in front are ruptured, the lower extremity of the humerus is then driven downwards in front of the bones of the fore-arm, the upper extremities of which are forced upwards behind the humerus, so that the coronoid process comes to occupy the nor- mal situation of the olecranon in the posterior articular fossa. Lateral motion. — Anatomists have been divided in opinion as to the possibility of any lateral motion being performed by the ulna on the humerus. Albinus, Boyer, Beclard, Cru- veilhier, and others, have denied the occurrence of it; Monro and Bichat, however, have dis- tinctly noticed it : they consider that this mo- tion is possible only in the semifixed state of the elbow, when the lateral ligaments are most relaxed : in complete flexion, as well as in ex- tension, the tense state of these ligaments effec- tually opposes any such movement. In my opinion it is easy to satisfy one's self as to the occurrence of this motion ; it consists of a slight degree of rolling of the middle prominent part of the greater sigmoid cavity in the fossa of the trochlea, produced by those fibres of the lower part of the triceps which extend from the con- dyle on each side to the olecranon, and by the action of the anconeus externally, (J. Hart.) ELBOW-JOINT, ABNORMAL CON- DITION OF.— Placed in the middle of the long lever which the upper extremity repre- sents, the elbow-joint is of necessity exposed to numerous accidents, the most remarkable of which are fractures and luxations. These, re- duced or unreduced, produce immediate and remote effects, to which it is our business in this place to advert. Congenital malforma- tions sometimes, though very rarely, are to be met with affecting this articulation, and require some brief consideration. The several structures too, which enter into the composition of the elbow-joint, are each and all occasionally affected by acute and f 2 08 ABNORMAL CONDITION OF THE ELBOW-JOINT. chronic inflammations, the consequences of which we cannot omit to notice, and many of these have their reputed source either in struma or syphilis, while others are attributed to an ar- thritic or to a rheumatic diathesis. I. -Accident. — Fractures. — Fractures of the bones of the elbow-joint may be classed as to their situation and direction : first, as they affect the lower extremity of the humerus ; and, secondly, as they engage the upper extremities of the bones of the fore-arm. 1. Simple fractures of the humerus near the elbow-joint may be transverse or oblique. When this bone is fractured transversely at its lower part immediately above its condyles, or in young subjects through its lower epiphysis, in either case the olecranon process is pulled backwards and upwards by the triceps, while the part of the humerus superior to the fracture, that is, almost the whole of the bone, is carried forwards, and forms such a projection below as much resembles a luxation forwards of the true articular extremity of the bone ; the prominence in front is also considerably increased by the in- clination forwards of the upper extremity of the lower short fragment, which is pulled in this direction by the supinators and pronators taking their fixed point below. The prominence for- wards, fori led by the angle of contact between the upper and lower fragments of the humerus, is covered in front by the brachialis anticus and biceps; and there is a projection behind formed by the olecranon process equally well marked ; so that, in comparing the posterior aspects of the two articulations, we see the ole- cranon process at the affected side exceed by its projection backwards that of the uninjured arm an inch or more : when to all this we add the observation that the antero-posterior diameter of the arm is evidently augmented, we have here many of the signs which might lead one to sus- pect the existence of the luxation of the bones of the fore-arm backwards. There is this differ- ence however, namely, that in fracture a crepitus can be felt, and the deformity is not accompa- nied with any changes of the normal relations existing between the olecranon and the con- dyles. Oblique fractures near the elbow-joint are usually prolonged into the articulation, and may be either external or internal. The frac- ture may traverse in an oblique line from without inwards, and from above downwards ; and then the external condyle and capitulum of the humerus will be detached from the shaft of that bone, and will constitute the external or inferior fragment ; or the fracture may take place obliquely from above downwards, and from within outwards, so as to comprehend the trochlea of the humerus and internal con- dyle in the inner fragment. In the first case, or external fracture, the posterior muscles of the fore-arm will have a tendency to pull the condyle downwards and backwards ; and in the second, the internal fragment with the trochlea will be drawn downwards and for- wards by the pronator muscles. Oblique fractures, extending into the elbow- joint, detaching the external condyle of the os humeri, maybe detected by the following sym- ptoms. There is considerable swelling and pain upon pressure on the external condyle : and the motions of the elbow-joint, both of ex- tension and flexion, are performed with pain; but the principal diagnostic sign is the crepitus produced by communicating a rotatory motion to the fore-arm. If the portion of the frac- tured condyle be large, it is drawn a little backwards, and it carries the radius with it ; but if the portion be small, this circumstance does not occur ; if the fracture of the external condyle take place immediately above it and within the synovial sac, it is stated by Sir A. Cooper that no union will take place except by means of ligament.* The oblique fracture of the external condyle is frequently met with in children ; a fall on the hand forwards may cause it, the impulse being transmitted along the radius to the capitulum and outer condyle of the humerus. The connexion of the radius with the ulna at this period of life is so loose that no resistance is afforded to the forcible ascent of the radius when a sudden fall for- wards on the palm of the hand occurs : and hence in the young subject particularly an oblique fracture of the outer condyle of the humerus can readily happen : at a late period of life, the connexions between the bones of the fore-arm are so strong and unyielding, that from a similar fall forwards on the hand, it is the lower extremity of the radius which would be obliquely fractured. There is at this moment in the Richmond Hospital a young woman who met with this oblique fracture of the external condyle of the humerus near the elbow, when she was only five years of age. The outer condyle and capitulum of the humerus were detached ob- liquely from the shaft of the bone and thrown backwards, carrying with them the head and upper extremity of the radius ; she now has very good use of her arm, but in consequence of the accident much deformity exists, parti- cularly when she extends the fore-arm. The obtuse angle salient internally, which the fore- arm forms with the arm in the natural state when it is fully extended, and the hand supi- nated, does not exist. On the contrary, in this case the salient angle is external, and corres- ponds to the outer condyle and head of the radius, and the retiring angle is placed inter- nally. (See Jig. 40.) The internal condyle of the humerus is fre- quently broken obliquely from the body of the bone, and the symptoms by which the accident is known are the following : when the fore-arm is extended on the arm, the ulna projects be- hind the humerus; the lower end of the hume- rus, too, advances on the ulna, so that it can be easily felt on the anterior part of the joint ; on flexing the fore-arm on the arm, the ulna resumes its usual position ; by grasping the condyles and bending and extending the fore- arm, a crepitus is perceived at the internal con- dyle : this accident usually occurs in youth, * See plate xxvi. fig. 1, of Sir A. Cooper's work on Fractures and Dislocations. ABNORMAL CONDITION OF THE ELBOW-JOINT. 69 Fig. 40. Fracture and retraction of the outer condyle of the humerus. although it may be seen in those advanced in life. It is an injury very likely to be mis- taken for a dislocation. 2. Fractures which engage the upper extre- mity of the bones of the fore-arm are chiefly confined to the ulna, for the radius very seldom suffers. Sometimes the olecranon process at the ulna is broken off, and occasionally a frac- ture of the coronoid process occurs, the con- sequences of which last accident are sometimes very serious. Sir A. Cooper gives us the fol- lowing history: "A gentleman came to London for the opinion of different surgeons upon an injury he had received in his elbow. lie had fallen on his hand whilst in the act of running, and on rising he found his elbow incapable of being bent, nor could he entirely extend it ; he applied to his surgeon in the country, who upon examination found that the ulna pro- jected backwards when the arm was ex- tended, but it was without much difficulty drawn forwards and bent, and the deformity was then removed. It was concluded that the coronoid process was detached from the ulna, and that thus during extension the ulna slip] ed back behind the inner condyle of the humerus." A preparation of an accident, supposed to be similar, is preserved in the Museum of St. Thomas's Hospital; the coronoid process, which had been broken off within the joint, had united by ligament only, so as to move readily upon the ulna, and thus alter the sigmoid cavity of the ulna so much as to allow in extension that bone to glide backwards upon the condyles of the humerus. Fracture of the olecranon. — This process of the ulna is not unfrequently broken off, and the accident is attended by symptoms which render the injury so evident that the nature of the case can hardly be mistaken. Pain is felt at the back of the elbow, and a soft swelling is soon produced there, through which the surgeon's finger readily sinks into the joint ; the olecranon can be felt in a detached piece elevated sometimes to half an inch and some- times to two inches above the portion of the ulna from which it has been broken. This elevated portion of bone moves readily from side to side, but it is with great difficulty drawn downwards ; if the arm be bent, the separation between the ulna and olecranon be- comes much greater. The patient has scarcely any power to extend the fore-arm, and the attempt produces very considerable pain, but he bends it with facility, and if the limb be left undisturbed it is prone to remain in the semiflexed position. For se- veral days after the injury has been sustained, much swelling of the elbow is produced, there is an appearance of ecchymosis to a consider- able extent, and an effusion of fluid into the joint ensues; but the extent to which these symptoms proceed depends upon the violence which produced the accident. The rotation of the radius upon the ulna is still preserved; no crepitus is felt unless the separation of the bone is extremely slight. Fractures of the upper extremity of the ulna are sometimes very com- plicated. Thus Mr. Samuel Cooper informs us that there is a preparation in the Museum of the London University, illustrating a case in which the ulna is broken at the elbow, the posterior fragment being displaced backwards by the action of the triceps ; the coronoid process is broken off ; the upper head of the radius is also dislocated from the lesser sigmoid cavity of the ulna, and drawn upwards by the action of the biceps. Luxations. — The bones of tho fore-arm are liable to a great variety of luxations at the elbow-joint ; the following arrangement will pro- bably be found to comprehend most of those accidents as yet known and described. 1. Luxations of both bones backwards; 2. Luxations of both bones laterally, complete and incomplete ; 3. Luxations of both bones laterally and posteriorly ; 4. Luxation of the ulna alone backwards; 5. Luxation of the radius alone forward ; 6. Luxation of the ra- dius externally and superiorly ; 7. Complete luxation of the radius backwards ; 8. Sub-lux- ation of the radius backward ; 9. Congenital luxation of the radius. 1. Luxation of both bones of the fore-arm backwards. — This luxation is the most frequent of all those to which the elbow-joint is liable; it is usually produced by a fall on the palm of the hand, the fore-arm being at the time ex- tended on the arm, and carried forwards, as when a person falling forwards puts out his hand to save himself. The patient suffers at the moment of the acci- dent an acute pain in the elbow-joint, and is often conscious of something having given way in the joint. The fore-arm inclines to a state of supina- tion (Jig. 41); the whole extremity is manifestly shortened ; the olecranon process rises very much above the level of the tuberosities; or, to speak more correctly, with reference to the po- sition of the limb, which is always presented to 70 ABNORMAL CONDITION OF THE ELBOW-JOINT. Fig. 41. Luxation of both bones backwards. us for examination more or less flexed, this process is placed much behind and somewhat below the plane of the condyles of the humerus. The tendon of the triceps carried back with the olecranon stands out in relief, as the tendo Achillis does from the malleoli. This part of the triceps thus standing out can be seized through the integuments by the fingers, and we perceive in front an interval between it and the back part of the humerus. Anteriorly, in the fold of the arm, through the thickness of the soft parts, we can feel a hard tumour, situated obliquely from without inwards and back- wards, formed by the lower articular extremity of the humerus. The rounded head of the radius can be seen prominent below the exter- nal condyle, and we can occasionally even sink the end of the thumb into the hollow of its cup-like extremity, and if now a movement of pronation and supination be communicated to it, the nature of the case becomes very evi- dent. The patient himself feels the arm powerless, and we find we can communicate to it but little motion. When we make the attempt to rotate or flex the arm on the fore-arm, we find our efforts resisted, and that we give the patient pain ; a little extension of the elbow-joint is allowed ; and we have invariably found that a lateral movement of abduction and adduction could be given to the fore-arm, motions this joint does not enjoy in the natural state, but which we can account for being now permitted, when we recollect the complete laceration the lateral ligaments must suffer in this injury. The transverse fracture of the lower extremity of the humerus, or a forcible separation of its lower epiphysis, are accidents most liable to be confounded with luxation of both bones backwards; but although the elbow projects much backwards, and there is a marked prominence in front, still the relative position of the condyles of the humerus and the olecra- non process is not altered in the fracture, as they have already been described to be, in the lux- ation. Add to this, that in the fracture the sur- geon can flex the patient's fore-arm on his arm, a movement which, in the luxation, the patient can neither himself fully perform, nor can it be communicated. In the case of the transverse fracture also, notwithstanding the apparent similitude at first with the luxation, when a steady extension is made by pulling the hand forwards, while the arm is fixed, all the marks of luxation disap- pear, to return again very shortly, when the extending force is relaxed. In fracture, too, a characteristic crepitus may be felt just above the elbow-joint, by rotating the fore-arm on the humerus. It is very true that, in some cases of luxation, the dislocated bones are very rea- dily restored to their place, and on the other hand, that a transverse fracture of the humerus may, after it is reduced, remain so for a little time, and thus we may perhaps account for the fact, that these accidents have been confounded with each other, and the mistake is a serious one. To guard against error in our diagnosis, it would be well, after the bones have been re- duced, to try the experiment of pushing the fore-arm backwards, while the arm is steadily pressed forwards ; if the accident has been a luxation, no change occurs, but if there has been a transverse fracture of the humerus, or of the coronoid process of the ulna, all appear- ances which erroneously induced a suspicion that the accident was one of luxation, are re- newed, but not so the error of attributing these appearances to a luxation, for now the exist- ence of a fracture can no longer be doubted. Lastly, after the bones, in a case of luxation, are apparently restored, it will be prudent to examine the head of the radius, and it will be right to be satisfied that this bone has also been replaced as well as the ulna, for, in the luxa- tion of both bones backwards, the connexion of the radius with the ulna by means of the coronary and oblique ligaments, may have suffered, and under such circumstances, if care be not taken, the restoration of the radius to the lesser sig- moid cavity of the ulna and capitulum of the humerus may have been forgotten, as we have known to have happened in one instance. When the luxation of both bones backwards is simple, and by mistake or neglect has been left unreduced, the case soon becomes irreme- ABNORMAL CONDITION OF THE ELBOW-JOINT. 71 diable ; the patient for ever loses the power of fully flexing the fore-arm, and the muscles of the arm become more or less atrophied ; the powers of pronation and supination also become impaired, but extension of the elbow-joint can be performed. Sir A. Cooper had an opportunity of dissect- ing a compound luxation of the elbow-joint, in which the radius and ulna were thrown back- wards, and the specimen is preserved in the Museum of St. Thomas's Hospital, and a re- presentation given in his work on dislocations : see plate xxiii. fig. 2. The coronoid process of the ulna was thrown into the posterior fossa of the os humeri, and the olecranon projected at the back part of the elbow, above its natura 1 situation, an inch and a half. The radius was placed behind the external condyle of the os humeri, and the humerus was thrown forwards on the anterior part of the fore-arm, where it formed a large projection. The capsular liga- ment was torn through anteriorly to a great ex- tent; the coronary ligament remained entire. The biceps muscle was slightly put on the stretch by the radius receding, but the brachia- lis anticus was excessively stretched by the altered position of the coronoid process of the ulna. This was a recent case ; but it would ap- pear from the dissections which have been made of cases which had been left for a long time unreduced, that a new bony cavity had been made on the front of the coronoid process of the ulna, while the brachialis anticus be- came the seat of ossific depositions. An in- teresting case of this kind is recorded by Cru- veilhier, and figured by him in his Anat. Pathol, plate iv. fig. 1. Beclard also met with a simi- lar case in dissection. 2. Lateral dislocation of the bones of the fore- arm.— Lateral dislocations of the elbow-joint are rare, and this circumstance is owing to the great transverse extent of the articular surfaces, to the inequalities which the corresponding surface of the humerus presents in the transverse di- rection, to the strength of the lateral liga- ments, and the attachment to them of the tendons of those superficial muscles which pass to the anterior and posterior part of the fore-arm, which tendons almost identify themselves with the laleral ligaments, and must considerably strengthen and support the joint laterally. Again, the force which would have a tendency to luxate the bones laterally can very rarely be directed in such a manner as to produce the luxation we are now considering, nor are the muscles ever so directed as to produce them. We find in authors circumstantial accounts of the symptoms of the complete luxation outwards and also of the complete luxation inwards ; but we have not had any opportuni- ties ourselves of witnessing these complete luxa- tions as the immediate result of accidents. Indeed we can scarcely conceive any complete luxation outwards to correspond exactly to the description given ; as we imagine that when- ever the bones of the fore-arm are completely thrown outwards, these bones must be drawn Fig. 42. Luxation outwards of both bones of the fore-arm, consecutive to caries of the trochlea and great sigmoid canity of the ulna. immediately upward along the outer side of the arm. We can conceive it possible, however, that the bones of the fore-arm may be completely dislocated inwards from the trochlea of the humerus, and still be restrained from yielding to those forces which would draw them upwards and inwards, by the great pro- jection inwards of the internal condyle of the humerus, which we know is so much more prominent than the external. We could scarcely mistake the case of complete lateral luxation of the fore-arm, whether it was inwards or outwards. In the incomplete lateral luxations of the bones of the fore-arm at the elbow-joint, the articular surfaces of the bones are still in con- nexion, but the points of contact of their naturally corresponding surfaces are altered more or less as to their relative positions to each other. In these luxations the bones of the fore-arm may be thrown partially outwards or partially inwards. In the luxation outwards, the cavity of the superior extremity of the radius abandons the lesser head of the humerus, and its cup-like extremity may be felt beneath the skin, while the great sigmoid cavity of the ulna corresponds to the capitulum of the humerus from which the radius has been dis- placed. As to the anatomy of the parts under such circumstances, the ligaments must be all torn, the biceps and triceps muscles must be pulled outwards in the direction of the bones of the fore-arm, into which they are inserted, the supinator brevis muscle cannot escape lace- ration, and the musculo-spiral nerve must be more or less stretched. There must be danger of such a luxation being rendered complete or even compound. One of the most remarkable of the external signs of this injury is an increase of breadth of the fore-arm in the line of the articulation. There is a considerable projection seen at the outer side of the arm formed by the head of the radius, and an angular depression immediately above this. On the inner side of the arm we see the 72 ABNORMAL CONDITION OF THE ELBOW-JOINT. prominence formed by the inner condyle of the humerus, and its lower extremity. The fore-arm is flexed, and the patient feels it impossible to move the joint. The deviation and curved direc- tion outwards given to the biceps and triceps, and approximation of the olecranon to the outer condyle of the humerus, all taken toge- ther sufficiently characterize this rare accident. In the incomplete luxation inwards, the cavity of the superior extremity of the radius, in abandoning the small head of the humerus, may be carried more or less inwards, and be placed under the internal border of the articu- lar pulley or trochlea of this bone, while the inner edge of the great sigmoid cavity of the ulna and olecranon process must project in- wards beneath the inner condyle of the humerus. The ligaments must be all torn as well as some of the muscles arising from the internal con- dyle of the humerus, the biceps and triceps are turned from their usual direction and are curved inwards, and the ulnar nerve must be more or less stretched. The external signs of incomplete luxation inwards are what the anatomy of the parts above described would lead us to expect; there is a remarkable increase of breadth across the line of the joint, perma- nent flexion of the fore-arm, and a powerless condition of the limb, all which were noticed m the former case. We must add to these a remarkable projection below and internal to the inner condyle of the humerus, formed by the internal edge of the great sigmoid cavity of the ulna. Our attention is also attracted by the approximation of the olecranon process and inner condyle of the humerus to each other, and the distance Of the olecranon from the outer condyle of the humerus, which forms a remarkable projection externally. 3. Under the head of lateral luxations of the elbow-joint, Sir A. Cooper has described accidents which might perhaps be more cor- rectly designated- — a, complete luxation of the bones of the fore-arm at the elbow backwards and outwards ; b, complete luxation of the bones of the fore-arm at the elbow backwards and inwards. a. Luxation of the bones of the fore-arm backwards and outwards. — In this case the ulna, instead of being thrown into the posterior fossa of the os humeri, has its coronoid process situated on the back part of the external con- dyle of the humerus. The projection of the ulna backwards is greater in this than in the former luxation, and the radius forms a pro- tuberance behind and on the outer side of the os humeri, so as to produce a depression above it. The rotation of the head of the radius can be distinctly felt by rolling the hand. b. Luxation of the bones of the fore-arm backwards and inwards. — Sometimes the ulna is thrown on the internal condyle of the os humeri, but it still projects posteriorly, as in the external dislocation, and then the head of the radius is placed in the posterior fossa of the humerus. The external condyle of the humerus in this case projects very much out- wards, and the usual prominence of the inter- nal condyle is lost. The olecranon process approaches nearer than natural to the middle line of the body, and is pointed inwards, being thrown more posteriorly than in any other lux- ation. 4. Luxation of the ulna alone directly back- wards.— The ulna is sometimes thrown back upon the os humeri, without being followed by the radius. The appearance of the limb is much deformed by the contortion inwards of the fore-arm and hand ; the olecranon projects, and can be felt behind the os humeri. Exten- sion of the arm is impracticable but by force, which will reduce the luxation, and it cannot be bent to more than a right angle. It is an accident somewhat difficult to detect, but its distinguishing marks are the projection of the ulna, and the twist of the fore-arm inwards. A specimen of this accident is preserved in the Museum of St. Thomas's Hospital ; the luxa- tion had existed for a length of time. The coronoid process of the ulna was thrown into the posterior fossa of the humerus, and the olecranon was found projecting behind the humerus much beyond its usual situation. The radius rested upon the external condyle, and had formed a small socket for its head, in which it was able to roll.* The coronary and oblique ligaments had been torn through, and also a small part of the interosseous ligament. The brachialis anticus was stretched round the trochlea of the humerus, and the triceps had been carried backwards with the olecranon. 5. Luxations of the upper extremity of the radius from the humerus and ulna. — When we look into the best books we possess for infor- mation on this subject, we must be struck with the remarkable discrepancy of the opinions we find expressed by the authors. Thus, upon the subject of luxation forwards of the radius, we find the celebrated Boyer stating that he doubts such a luxation can occur without being complicated with a fracture. Sanson states that this luxation forwards has never been observed, and moreover advances what he considers as anatomical and physiological explanations, to show the impossibility of such an occurrence. Sir A. Cooper, on the contrary, gives six examples of the luxation of the upper extre- mity of the radius forwards. The French writers state of the luxation of this extremity of the radius backwards, that although it is rare it has been many times witnessed, while Sir A. Cooper, alluding to this luxation back- wards, says, " this is an accident which I have- never seen in the living," but he gives an anatomical account of the appearances found in a subject, the history of which was unknown, brought into St. Thomas's Hospital for dissec- tion. Having thus stated the different opinions of authors upon this subject, we shall proceed to give an account of — a, the luxation of the upper extremity of the radius forwards ; b, of its luxation laterally and upwards ; c, of its luxation backwards ; d, of its sub-luxation ; e, of its congenital luxation backwards. * See plate xxiv.fg. 2, in Sir A. Cooper's work. ABNORMAL CONDITION OF THE ELBOW-JOINT. 73 a. Luxation of the radius at the elbow-joint forwards. — The symptoms of this accident are as follows : the fore-arm is slightly bent, but cannot be brought to a right angle with the arm, nor can it be completely extended ; when it is suddenly bent, the head of the radius strikes against the fore part of the humerus, and pro- duces so sudden a stop to its motion as at once to convince the surgeon that one bone strikes against the other. The hand is placed in a prone position; but neither its pronation nor its supination can be completely performed, although its pronation may be nearly complete. The head of the radius may be felt on the front and upper part of the elbow-joint, and if rota- tion of the hand be attempted, the bone will be perceived to roll; this last circumstance and the sudden stop to the bending of the arm are the best diagnostic marks of this injury. In the dissection of this case, the head of the radius is found resting in the hollow above the external condyle of the os humeri. The ulna is in its natural position. The coronary and part of the capsular ligaments as well as the oblique and a portion of the interosseous liga- ments are torn through. The laceration of the latter ligament allows of the separation of the two bones. The biceps muscle is shortened (fig- 43). Fig. 43. Luxation of the radius forwards. We have known an instance in which this accident was produced in the following man- ner : the patient in endeavouring to protect his head from a blow aimed at him by a man who with both hands wielded a spade, received the force and weight of the spade on the edge of the ulna, which, at the same time that it pro- duced a compound fracture of this bone, also dislocated the radius forwards. This latter complication not having been discovered in time, remained ever afterwards unreduced. b. Lateral dislocation of the upper extremity of the radius. — This is an accident we find alluded to for the first time by Sir A. Cooper, in the appendix to the edition of his work on luxations. He does not adduce any recent case of it, but states that Mr. Freeman brought to his house a gentleman, aged twenty-five, whose pony having run away with him when he was twelve years old, he had struck his elbow against a tree, while his arm was bent and advanced before his head, in consequence of which the olecranon was broken, and the radius luxated upwards and outwards above the external condyle. When the arm was bent, the head of the radius passed the os humeri ; he had a useful motion of the limb, but neither the flexion nor the extension was complete. As the case here stated is the only one we are acquainted with on record of luxation of the radius upwards and outwards, we may be perhaps excused for exceeding our ordinary limits by relating the following case of this accident ; the subject of it was a very intelligent medical student, about twenty-three years old, and we shall give the case nearly in his own words : — He writes as follows : " When I was very- young, a blow was aimed at my head by a person having a heavy boat-pole in his hands. I endeavoured to save my head by parrying the blow with my left arm. I received the pole on the middle and back part of the fore-arm with a force which knocked me down, and caused a wide lacerated wound where the pole came in contact with it. Whether a luxation of the radius occurred at this time or not was not known, but ever since the accident the arm has been weak, and about seven years ago the weakness increased, and it became liable to partial luxations forwards upon the slightest causes, which luxations I reduced myself by making extension with my right arm, until at length I got a severe fall, which dislocated it to such an extent, forwards and outwards, as to defy my attempts to restore it. The arm was locked in the flexed position, and the head of the radius was to be felt high up, and pro- jecting slightly outside the external condyle of the humerus. The biceps muscle was con- tracted, and its tendon was very prominent, hard, and tense, like a bowstring. The hand was supinated. I suffered little pain, except when extension was attempted, when it became intense. Sir A. Cooper remarks, in his cases of luxation of the radius forwards, that the fore-arm is slightly bent, but cannot be bent to a right angle, nor completely extended. My arm was bent to an acute angle, and could not admit of the slightest extension. The luxation was reduced by extension, and in six weeks passive motion was begun; but I found it painful to use it, and the head of the radius would often catch in the ridge above the ex- ternal condyle, but on extending the arm it returned with a noise into its place. A month, however, did not pass before I was one morn- ing awakened in making some awkward move- ment in my bed, and my arm became luxated worse than ever. On this occasion the surgeon who heretofore had easily replaced the bone found it impracticable to effect it, and called in Mr. Colles to his assistance ; but although much force was used it was in vain. From this time the head of the radius never was 7-! ABNORMAL CONDITION OF THE ELBOW-JOINT. returned back to its proper situation, but habi- tually remained dislocated completely forwards in front of the external condyle. The liga- ments seemed to have been so lacerated, and the joint felt so weak, that I was in constant terror lest the bone should be further luxated as formerly, and that it should again slip over the external condyle of the humerus. I could extend my arm, but not fully, and could rotate it, but could not flex it sufficiently to use my fork at dinner. In this state I remained for six years, and in the winter of 1834-5 the radius was again luxated laterally over the external condyle of the humerus by a fall from my bed. Now the difficulty experienced in bringing the bone back to the situation it had so long occu- pied in front of the external condyle, was ex- treme. I went to the hospital, and two sur- geons, assisted by six of my brother pupils, could not, with all their force, reduce the bone. The pulleys were also now used, but without suc- cess. Dr. O'Beirne and the late Dr. M'Dowel were called into consultation ; they placed me sitting on my bed, and fixing the hollow angle at the bend of the elbow against one of the bed-posts, they used great force to straighten it, in which they succeeded; that is to say, they replaced the bone, not into its original berth, but back to the new socket, which had been formed for it in front of the external con- dyle, where it had been lodged for six years previously to the last accident, and where it now remains. At this moment it presents all the characters assigned to the luxation of the radius forwards ; the rounded head of this bone is quite prominent in front of the external con- dyle of the humerus, in which situation it seems to have worked for itself a socket, and behind the head of the radius a deep depres- sion exists. The arm has a rounded appear- ance, and the fore-arm is .much wasted." This case seems to us important as proving three circumsi.ances : 1 . that a partial luxation forwards of the radius can exist from relaxation or elongation of ligaments ; 2 . that this partial luxation or weakness of the joint is readily convertible into the true luxation forwards ; and, 3. that in the case of unreduced luxation of the radius forwards the patient is still in danger of further luxation of this bone laterally, or above the capitulum and outer condyle of the humerus. e. Luxation of the tipper extremity of' the radius backwards. — This luxation would appear to be the most frequent the upper extremity of the radius is liable to, although it cannot be considered a common accident. When, how- ever, we consider the functions of this joint and its form, we shall not be surprised to find the luxation backwards- more usual than that forwards. The articulation is less sustained posteriorly by muscular parts than in front, when the fleshy bellies of the supinators cover and support it. There is also much latitude given to the movement of pronation, and the pronators are very powerful muscles. During a forced pronation, the radius becomes very oblique, and its upper extremity has a strong- tendency to pass behind the axis of the hu- merus. The motion of supination, on the contrary, is not so frequent, the muscles to effect it are not so powerful, and the oblique and interos- seous ligaments, which afford no restraint in the motion of pronation, are, on the contrary, soon rendered tense, and oppose a forced supination, which is the movement most likely to be followed by the luxation forwards. We think, therefore, we have physiological grounds for our belief that the luxation of the radius backwards ought to be the most frequent lux- ation of the radius at the elbow-joint. When the luxation of the upper extremity of the radius backward has occurred, the patient feels at the moment a severe pain in the region of the joint. The fore-arm is flexed, and the hand remains fixed in a state of pronation. Supination cannot be effected either by the voluntary action of muscles or by force ap- plied, and each effort, tending to produce this effect, is attended with a considerable augmen- tation of pain. The hand and fingers are held in a moderate state of flexion. Finally, the superior extremity of the radius forms a mani- fest prominence behind the capitulum or small head of the humerus. When the bone is left unreduced, many of the motions of the fore-arm are rendered im- perfect, particularly supination ; but the shoul- der articulation becomes somewhat more free, and in some degree this circumstance makes up for the deficiency. Sir A. Cooper, who has not seen any example of this luxation of the radius backwards in the living subject, has given us an account of a dis- section of this injury. He informs us that in the winter of 1821 a subject was brought for dis- section into the theatre of St. Thomas's Hos- pital, in which was found this luxation, which had never been reduced. The head of the radius was thrown behind the external condyle of the humerus, and rather to the lower extre- mity of that bone. When the arm was ex- tended, the head of the radius could be seen as well as felt behind the externat condyle of the humerus. On dissecting the ligaments, the coronary ligament was found to be torn through at its fore part, and the oblique ligament had also given way. The capsular ligament was partially torn, and the head of the radius would have receded much more had. it not been supported by the fascia which extends over the muscles of the fore-arm. d. Sub-luxation of the tipper extremity of the radius, with elongation of the coronary ligament. — While Boyer denies the possibility of any partial luxation of the upper extremity of the radius, he describes very clearly an abnormal condition of the radio-humeral joint, of which we have seen many examples, and which perhaps we may call a sub-luxation. The ligaments which connect the head of the radius to the ulna, in the cases above alluded to, undergo a gradual relaxation and elonga- tion, so that whenever an unusual effort is made to produce a strong pronation of the ABNORMAL CONDITION OF THE ELBOW-JOINT. 75 fore-arm, the head of the radius is permitted to pass backwards, somewhat behind its na- tural situation ; but as soon as the effort ceases, the radius resumes its natural position in the lesser sigmoid cavity of the ulna. A true lux- ation in these cases cannot be said to happen, unless the effort of pronation is sufficient to bring the superior extremity of the radius behind the small head of the humerus ; when- ever this has occurred, then the sub-luxation is converted into the complete luxation of the radius backwards, and presents all the cha- racters of this accident, and it cannot be re- placed without the assistance of art. It is known to anatomists that the radio-cubital joint is not advanced much in its development in infants ; that the lesser sigmoid cavity is as yet small and shallow ; and that the coronary ligament of the radius is proportionally longer and more yielding than it is destined to be in after life. This articulation, however, is fully equal, even at this earliest period of life, to sustain any efforts that its own pronator muscles can communicate to it ; but it is by no means constructed so as to be able to resist those forced movements of pronation and stretching we see too frequently given to the fore-arms of infants of a tender age, by their attendants, who in lifting them from the ground usually seize them by the fore-arms, these being at the time in a full state of pro- nation. Thus we find that in delicate children the foundation is laid for that elongation of the coronary ligament, which ends in the con- dition of this joint we have denominated sub- luxation. We have usually observed that the subjects of this affection were delicate from their youth, and that sometimes only one, and that frequently both arms were affected ; that in all cases the extremity was more or less deformed, having a bowed appearance, the convexity being external ; that a very evident protuberance could be seen and felt in the situation of the head of the radius ; and that the patient had nearly perfect use of the arm, although he could neither fully flex nor extend it. When the surgeon places his thumb on the external condyle of the humerus and head of the radius in one of these cases, and at the same time has the fore-arm supinated, the head of the radius is felt to rotate in its proper place, and on its axis, as in its perfect condition ; but if now a forced movement of pronation be given to the head of the radius, the latter will be observed to slip backwards towards the olecranon process : every time the patient him- self fully pronates the fore-arm, the sub-lux- ation occurs, and in supination the radius resumes its place again. This relaxation of the ligaments of the radio-cubital joint, no matter how produced, at all events predisposes those affected with it to the more complete luxation of the radius backwards. e. Congenital or original luxation of the superior extremity of the radius backward,^ — Dupuytren is the first pathologist who has spoken of the congenital luxation of the radius; he met with a case of the kind in dissection, and described it in his lectures. He found that the superior extremity of each radius had abandoned its natural situation, and was found situated behind the inferior extremity of the humerus, having passed this extremity an inch at least. This disposition being absolutely the same on each side of the body, there existed no difference between these two luxations, which were probably conge- nital. It is also stated that Dupuytren had mentioned that about twenty or twenty-five years before he dissected the case now alluded to, he had seen a case nearly similar, but he was unwilling to speak positively on these cases, as the history was unknown, and acci- dent or disease might have produced similar results. Cruveilhier, in his very valuable work on Pathological Anatomy, quotes the above ob- servations from Dupuytren's lectures, and seems to disagree entirely with the celebrated surgeon of the Hotel-Dieu, advancing it as his opinion, that it vvould be much more na- tural to suppose that the cases described by Dupuytren were not congenital, but rather very old luxations, a long time left unre- duced. It is very true that Dupuytren speaks with hesitation about the matter, as he appears to have met with but two cases, nor can any one speak with certainty on this subject, until ob- servation on the living, and anatomical in- vestigations, shall be combined to elucidate the matter ; but we think that already enough can be adduced to shew, that we have strong grounds for believing that such a congenital defect as luxation of the upper extremity of the radius backwards may be occasionally met with, and this is an opinion we think our- selves authorised to advance, because of the facts and reasons we can adduce to support it. In the Museum of the Royal College of Sur- geons in Ireland, there is a specimen, which the writer considers to be one of congenital lux- ation of the upper extremity of the left radius backwards; fig. 44 is a representation of it. The outer condyle of the humerus exists, but in front of it there is no rounded head or capitulum for the radius, or any trace of the usual convex articular surface ever having existed. The coronoid process and great sig- moid cavity of the ulna are unusually large transversely, and stretch almost the whole way across the lower articular extremity of the humerus, which is entirely formed into one single trochlea wider than natural. The head of the radius, which seems never to have been adequately developed, is situated behind the plane of the outer condyle of the humerus. The tubercle of the radius is much enlarged, and leans against the lesser sigmoid cavity of the ulna, while the neck of the radius, directed somewhat backward, is twice its natural length, and instead of reaching merely to the level of the lesser sigmoid cavity of the ulna, stretches as high up along the ulna as to reach near to the level of the summit of the olecranon pro- cess, while the carpal extremities of the radius 76 ABNORMAL CONDITION OF THE ELBOW-JOINT. and ulna are, in their natural state, on an even line with each other. There is scarcely any interosseous interval, the bones seem so closely connected with each other. Indeed, from the inspec- tion of this preparation, we may justly infer that the fore-arm during life had remained much in a state of semiflexion on the arm, and of rigid pronation, and that the movement of supination was nearly impracticable. This defective formation, or atrophy of the capitu- lum and increased deve- lopement of the trochlea of the humerus, which was so formed to ac- commodate itself to the unusual breadth acquired by the coronoid process and the whole of the ulna, must not be con- sidered unprecedented. We find, by referring to the beautiful work of Sandifort, (the Museum Anatomicum, table ciii. fig. 3,) a case similar to the above delineated (fig. 45). In referring to it, the author states that the bones of the fore-arm were anchylosed , that the form of the ca pitulum was the head of the radius ■was luxated completely backwards, and that the ulna alone remained in articulation with the hu- meri s ; the parallelism between these two cases will be still more fully seen, when, speaking of the lower articular extre- mity of the humerus, we . ; Congenital luxation of the lost, tnat Tadius backlvarfom Fig. 45. ■ ' IP 1 1 1 k it find that he says," Figura A ergocapituliperiil.Rotula /llOHMHB|>t unica, sed major forma- I^J^^|' tur;" and of the ulna, " insignem acquisivit am- plitudinem et totam infe- , r. . , Vonqemtal malformation norem ossis humeri par- »f HgU hJumerm _ tem admittere potuit. trochlea enlarged— no In examining very capitulum. lately the splendid col- lection of morbid specimens contained in the Museum of Guy's Hospital, the writer's attention was caught by observing a pre- paration of the radius and ulna, belonging, he is certain, to the same class of diseases now under consideration, namely, congenital luxations of the radius. In this preparation there is a very oblique relative position of the bones of the fore-arm to each other. While their carpal extremities are exactly upon a line with each other below, the neck of the radius is elongated upwards, and the head of this bone is displaced much backwards, and is situated behind and below the outer condyle of the humerus, and reaches nearly to the summit of the olecranon. The coronoid pro- cess and great sigmoid cavity of the ulna have acquired much breadth, and what is remark- able in this case, and in which it differs from any other we have seen, is, that a process of caries had been going on in the articulation. Cruveilhier has given four drawings of two cases of complete luxation backward of the radius, which he however does not consider to be congenital. Nor is it in our power abso- lutely to prove that they are specimens of congenital luxations backwards, although we feel persuaded that all the cases we have re- ferred to, these inclusive, are very curious specimens of this congenital deformity of the radio-humeral articulation. The previous history of all the cases we have collected is totally unknown ; it is re- corded of them all, that the arm was re- markable for its deficient development, that the fore-arm was in a state of demi-pro- nation and demi-flexion, that the movement of extension was incomplete, and of su- pination impossible. Cruveilhier, in the ac- count he has given of both his cases, states that the superior extremity of the radius was at the level of the summit of the olecranon process (Jig- 46), and that the infe- rior or carpal extremity of the two bones of the fore- arm were on the same pre- cise line below, and that no deformity here existed. The head of the radius and tu- bercle were deformed, or ra- ther imperfectly developed, while there was an elonga- tion of the neck of the ra- dius upwards for more than an inch. Cruveilhier can- not concur with those who consider these cases as ex- amples of congenital luxa- tions, but looks upon them as old luxations, which had been left unreduced. For our part we cannot see in these pathological ob- servations any thing to con- vince us that any one of the cases alluded to was an old luxation originally produced by accident or disease. Sup- pose, for argument sake, it be admitted that, from long disease, the form of the , capitulum was altogether Malformation of the j £ fa t, d; nQ radius, in winch , > ... , it was found as longer m contact with it, and long as the ulna, that the acquired breadth of Fig. 46. 1 ABNORMAL CONDITION OF THE ELBOW-JOINT. 77 the sigmoid cavity of the ulna was the result of a natural effort to compensate for the loss of strength the joint suffered from the dislocation of the radius. Still, supposing it possible that the surface of the capitulum of the humerus could be so completely removed, under such circumstances, as we find it was in the cases of which Jigs. 44 and 45 are delineations, we may ask, is it likely, from accident or disease, that both elbow-joints should be similarly affected, as they were in Dupuytren's cases. Another circumstance in our mind cannot be accounted for, unless by supposing these cases congenital, namely, the alteration and great elongation of the neck of the radius. " L'ex- tremite superieure de chaque radius avait abandonne sa situation naturelle, se trouvait place derriere l'extremite inferieure de l'hu- merus, et depassait cette extremite d'un pouce au moins. Cette disposition etait ab- solument la meme de chaque cote du corps." We know of no process which could take place in the head and neck of the radius after it had been dislocated, which could satis- factorily account for the elongation of the radius, which has been remarked in these cases. While looking on them as congenital, we need not be surprised at it ; for we have known the neck of the femur elongated and atrophied, in the case of congenital luxation of the femur, and have very frequently seen the lower extremity of the ulna exceed in length by half an inch the corresponding extremity of the radius ; and these were cases in which no doubt could be entertained that they were congenital. Disease. — -Acute and chronic inflammation produces effects on the membranes, cartilages, and bones entering into the composition of the elbow-joint, which will be found nearly analo- gous to those which the same morbid action pro- duces on similar structures in other articulations. A few local peculiarities, if we may so call them, when the elbow is the seat of the acute or chronic disease, should alone occupy our atten- tion here. Synovitis of the elbow-joint, uncombined with any affection of the other structures, is rare ; it may, however, present itself either in the acute or subacute form. Increased effusion of fluid into the joint, accompanied with the usual local and sympathetic phenomena of in- flammation, is the result. Two well-marked oblong swellings at each side of the olecranon process in these cases first present themselves, which after a time, if the disease proceeds, join and form one swelling, which extends up the back of the arm, occupying the cellular in- terval existing between the back part of the humerus and the front of the triceps muscle, opposite to the outer condyle of the humerus and head of the radius; the supinators arising here are, in severe cases, occasionally elevated and thrown out from the bones by a soft tumour, which, upon examination, conveys to the fingers a distinct feeling of a fluid contained beneath. The nature of the accumulated fluid will, when the joint is cut into, be found to vary. When the effusion has followed an acute attack of in- flammation of the membrane, it will be gene- rally found to be purulent, though sometimes we have observed the quality of the synovia but little altered, except that it was more or less turbid. When the contents of the synovial sac have been washed away, the membrane will be seen to be highly vascular, and the ves- sels of the subsynovial tissue congested with blood, and its cells infiltrated with se- rum; while, if fine injection, coloured with vermillion, is thrown into the vascular system of these parts, the unusual redness the mem- branes assume can only be compared in height of colouring to the membrane of the eye in acute conjunctivitis. With this intense red- ness of the surrounding membranes is strongly contrasted the appearance of the cartilages of the joint; these, but little altered from their natural colour, are seldom in this articulation found covered with vascular membranes, and even when the surrounding structures are mi- nutely injected, the fluid cannot be made to penetrate the synovial investment of the carti- lages. Cartilage. — When acute inflammation has existed in the synovial membrane or bones of the elbow-joint, the articular cartilages covering these will very frequently be found to have assumed, in patches, a dull yellow colour ; in the latter discoloured points the cartilage is soft- ened, and a blunt probe slightly pressed will sink into its structure, and its subjacent surface will be found to be detached. A new vascular membrane having been interposed between the cartilage and the cancellous structure of the bone, this elevation and partial detachment of the articular cartilages from the heads of the bone, and interposition of a new organized mem- brane, are probably the usual preludes to those other changes we notice. Thus sometimes a leaf or flap of the articular cartilage, adherent only by an edge, hangs into the cavity of the joint, and again fragments of this structure completely detached are found loose in the in- terior of the articulation. In these instances there is reason to conjecture that the diseased action which detached the cartilage began on the surface of this structure contiguous to the bone. We have occasionally, however, evidence of ulcerative absorption having commenced on the free surface of the cartilage. The peculiar worm-eaten appearance which the surfaces of cartilages next the cavity of the joint occa- sionally present, and which, wherever it exists, is considered by many pathologists to be the result of a process of ulceration which had be- gun on the free surfaces of the articular carti- lages, has been occasionally though rarely seen in the elbow-joint ; much more frequently in examining elbow-joints which have been the seat of disease, the articular surfaces of the bones have been found extensively divested of their cartilages ; a few patches of them alone here and there remain ; and these, though apparently thinner than natural, are of their ordinary tex- ture, and are firmly adherent to bone. Such extensive removal of cartilage, which has exposed the cancelli of the heads of the bones, has generally been the result of some 78 ABNORMAL CONDITION OF THE ELBOW-JOINT. very violent attack of inflammation, which, no matter in what situation it had originated, ulti- mately we find had not spared any of the tis- sues entering into the formation of the articu- lation. Bone. — The elastic white swelling (which is one of the usual external signs of this articular caries when the bones of the elbow-joint are the seat of the affection) is always situated poste- riorly, and gives a characteristic appearance and a rounded form to the back part of the elbow-joint, which cannot be mistaken nor misunderstood. The wasted appearance of the arm above and of the fore-arm below makes this swelling more conspicuous, and the whole limb remains habitually in the semiflexed posi- tion, with the fore-arm somewhat prone ; every movement of the articulation causes the patient much pain. The disease, thus arrived at its second or third stage, may remain stationary for a time or terminate in an anchylosis of the bones ; commonly, however, the morbid pro- cess goes on. Luxation of one or both bones of the fore-arm occurs, symptomatic abscesses present themselves, and these after a time make their way to the surface, and discharge their contents through openings, sometimes near, and frequently at a distance from the joint; and thus, at length, we see formed direct outlets as well as sinuses and fistulous canals, which give exit to exhausting discharges. The pain and irritation attendant on the disease itself, added to all these, give rise to hectic fever, which too frequently nothing but the desperate measure of amputation will arrest. The disease, which produces such serious consequences, often be- gins very insidiously, either in the head of the radius and external condyle of the humerus, or in the trochlea of this bone and the great sig- moid cavity of the ulna. When the disease begins at the radial side, the pain runs along the course of the musculo-spiral nerve, and there is a manifest swelling externally in the situation of the radio-humeral articulation : although there is even now a marked tendency in the fore-arm to remain in a semiflexed posi- tion, still gentle flexion and limited extension are admissible ; but when the radius is pressed against the humerus, and a movement of rota- tion at the same time is given to the fore-arm, much pain is complained of. The disease may go on, confining itself chiefly to the radial side of the elbow-joint through its first stage of pain and swelling ; through its second of effu- sion of fluids and relaxation of the coronary and external lateral ligament; and, thirdly, to dislo- cation backwards of the head of the radius, and even to suppuration and discharge of mat- ter through an ulceration or slough of the inte- guments. When the caries has commenced in one of the opposed surfaces of the trochlea of the humerus or great sigmoid cavity of the ulna, the swelling and effusion are first noticed in- ternally at the side of the olecranon and inter- nal condyle. The pain extends to the wrist along the course of the ulnar nerve ; the fore- arm is in this case also in a state of semi- flexion, and any attempt to extend or increase the degree of flexion causes very severe pain, while, on the contrary, a movement of rotation of the fore-arm is permitted. If the disease pro- ceeds, the great sigmoid cavity of the ulna be- comes wider and deeper, and the humerus ad- vances on the coronoid process ; the internal lateral ligaments are relaxed, and the triceps drags back the fore-arm, so that the olecranon process projects somewhat posteriorly, and there is a tendency to a displacement backwards. Whether the disease has originated on the radial or ulnar side of the joint, it very generally spreads so as to involve the articular surfaces of the three bones, and now the disease, termed scrophulous white swelling, becomes fully esta- blished, and is easily recognized by the usual signs. Besides dislocation backwards, either of the radius or of the ulna singly, or of both these bones together, lateral displacements of the bones of the fore-arm at the elbow have been noticed as a consequence of caries ; nor need we be surprised at such variety of posi- tion being assumed by the bones, when inflam- mation has softened the strong lateral ligaments and caused their ulceration. While the patient is confined to bed or to the horizontal posture, the mere position which is given to the fore-arm on the pillow will influence the direction of the displacement that will occur. We have seen, under such circumstances, complete late- ral displacement of both bones of the fore-arm outwards. The internal condyle of the hume- rus pressing against the integuments covering it had caused a round slough, through which the internal condyle of this bone protruded, while the rounded head of the radius had on the outer side caused a similar slough and ulceration of the integuments, through which the upper cup-like extremity of this bone had protruded. This lateral displacement of both bones of the fore-arm outwards, whether occurring sud- denly from accident, or slowly from the effects of articular caries, if it be complete, must always (we imagine) be followed by a consecutive dislocation upwards. In this case of caries above alluded to, we found the whole extremity somewhat shortened, that the hand remained habitually prone, and that the fore- arm (in a state of semiflexion as to the arm) was directed with considerable obliquity in- wards. It was plain that the causes of all these external signs were, that both bones of the fore-arm having their normal relation to each other, were first carried completely out- side the inferior extremity of the humerus, and were then drawn upwards above the level of the outer condyle of this bone. The olecranon process was not thrown at all backwards, but was situated immediately above and outside the external condyle of the humerus ; the coro- noid process was in front of this bone; the inner semilunar edge of the great sigmoid ca- vity therefore corresponded to the convexity of the outer side of the humerus, and seemed, as it were, to embrace this bone here so as to for- bid any further retraction of the fore-arm. When we proceed to examine an elbow-joint which has been the seat of a scrophulous white ABNORMAL CONDITION OF THE ELBOW-JOINT. 79 swelling that had presented the usual charac- ters of this disease in its advanced form, we usually notice the surface of the skin studded over here and there with the orifices of fistulous canals ; these are found generally to have pro- ceeded by a winding course, either from the cavity of the elbow-joint or from the cancellous structure of the bones, or from both these sources. W hen a section is made of the bones in this advanced period of the disease, they will generally be found to be softened in the interior, and to contain a fatty or yellowish cheese-like matter in their cells ; when exam- ined in an earlier stage of this scrophulous caries, these organs are generally found to be pre- ternaturally red and vascular, and with much less proportion of earthy matter than natural, so that they admit not only of being cut with a knife without turning its edge, but yield and are crushed under very slight pressure. We have also occasionally opportunities of examining the joint when the process of caries would appear to have been arrested and to have given place to a new growth of bony vege- tations around the joint ; under such circum- stances, conical granulations, several lines in length, shoot out like stalactites around the trochlea of the humerus and from the olecranon and coronoid processes of the ulna ; the bones are, however, in these specimens remarkably light, porous, and friable. In some cases, however, the caries of the bone has altogether ceased, and a process of anchylosis has been es- tablished, and the fore-arm is flexed on the arm : a section through the elbow-joint longitudinally will in such cases frequently exhibit a com- plete continuation of the cancelli through the joint from the cells of the humerus to those of the radius and ulna. Rheumatism. — The elbow-joint, like all the other articulations, is liable to attacks of acute rheumatic inflammation, the external signs of which differ but little from those which we observe to attend an ordinary case of acute synovitis. The disease, however, seldom fixes itself for any time upon this or any one joint in particular and usually terminates favourably, so that opportunities seldom occur of ascer- taining by anatomical examination the effects of this species of inflammation in the different structures of the elbow-joint. But this articu- lation is, in the adult and in those advanced in life, affected by a disease which, for want of a better name, is termed chronic rheumatism, the anatomical characters of which are very remarkable, yet they never have received from pathologists that attention they appear to us to deserve. In these cases the elbow- joint becomes enlarged and deformed; its or- dinary movements, whether of flexion, exten- sion, or rotation, become restricted within very narrow limits ; and when we communicate to the joint any of these motions, the patient complains of much pain, and a very remarkable crepitation of rough rubbing surfaces is per- ceived : a careful external examination of the joint will in such circumstances enable us to detect foreign bodies in the articulation. Some of them are small, but others occasionally are met with of a very large size, and can easily be felt through the integuments. Sometimes the synovial membrane of the joint itself is much distended with fluid, and the bursa of the ole- cranon is likewise affected, in which small fo- reign bodies are also to be detected : sometimes, however, there would appear to exist in the in- terior of the joint even less synovia than natural. The muscles of the arm and fore-arm for want of use are more or less wasted and atrophied. As the external appearances vary, so also do we find the anatomical characters of the disease to pre- sent varieties, some of which deserve notice. We have found the most general abnormal ap- pearance to be that the cartilages are removed from the heads of the bones which are greatly enlarged, and that these articular surfaces are covered by a smooth porcelain-like deposit, and after a time attain the polish and smooth- ness of ivory : the trochlea of the humerus, also, and corresponding surface of the great sigmoid cavity of the ulna are also marked with narrow parallel sulci or grooves in the di- rection of flexion and extension. In these cases the radio-humeral joint is- likewise affected, the head of the radius becomes greatly enlarged, and it assumes quite a globular form, while the anterior and outer part of the lower extremity of the humerus will have its capitulum or con- vex head not only removed, but here the humerus will be found to be even excavated to receive the head of the radius, and to accom- modate itself to the new form it has acquired from disease. In many cases where the radius had become thus enlarged and of a globular form, the writer has found the cartilage removed altogether and its place occupied by an ivory- like enamel. In two examples he has seen a depression or dimple in this rounded head of the radius, similar to what naturally exists in the head of the femur, and in these two cases, strange to relate, a distinct bundle of ligament- ous fibres analogous to a round ligament passed from the dimple or depression alluded to, con- necting this head of the radius to the back part of the sigmoid cavity of the ulna. In some few cases, when the external signs of this chronic disease in the elbow-joint were present, we have found the bones of this articulation enlarged, hard, and presenting a rough porous appearance, while the cartilage was entirely removed ; but in these specimens no ivorv deposit was formed. These were cases in which the same disease existed locally, and the same disposition prevailed in the constitution ; but from the bones having been kept in a state of quietude, the rough surfaces of the articular extremities had not been smoothed by the effects of friction, nor an ivory-like enamel formed. We believe that in such cases, were life prolonged, anchyloses would be established : in other instances the head of the radius has not been found enlarged as above described, but otherwise altered from its natural form. The superior articular extremity of this bone has been found excavated from before back- wards, its outline not being circular nor exactly oval but ovoidal, accurately representing on a small scale the glenoid cavity of the scapula. 80 ABNORMAL CONDITION OF THE ELBOW-JOINT. It may be remarked that one of our patients, a man, aged sixty, in the surgical wards of the House of Industry, who had for many years suffered from the severest forms of chronic rheumatism in all the articulations, got diarrhoea and died. The writer had previously noted in particular the condition of the right elbow- joint; the motions of flexion and extension were very limited, attended with much crepi- tation, and caused to the patient very great pain. The exact condition of the bones described in the preceding paragraph existed, and the loss of the circular outline of the radius fully accounted for what we had in this case previously noted, viz. that to remove the hand from the state of pronation in which it habitually remained, or to communicate any movement of rotation to the radius was nearly impracticable; the glenoid-shaped surface for the head of the radius allowed of flexion and extension in the radio-humeral articulation, but any except the perfect circular form was ill- suited to permit any rotatory movement of the radius on the ulna. This then is a peculiar disease which causes a complete removal of the articular cartilage from the head of the bones of the elbow-joint, so that the porous sub- stance of the bones becomes exposed : they do not become carious, but on the contrary they are enlarged, hard, aud their surfaces seem to expand. If the joint be much used, the effects of friction become evident; if kept at rest, they are rough, and anchylosis may take place. From the phenomena we observe in the variety of cases that present themselves, we may infer that, when this disease affects the elbow-joint, in whichever bone most vitality exists and most active nutrition is going on, enlargement would appear to take place, while in the bone which is softer arid in which the process of nutrition is least, the effects of fric- tion become of course most manifest. Thus, in some cases, as already mentioned, we have found the head of the radius greatly enlarged and of a globular form, and the outer condyle of the humerus excavated to adapt itself to this convexity, while on the contrary, in other cases the outer condyle of the humerus seemed to have been the seat of active nutrition, and the head of the radius to have been rendered soft and to have yielded to the effects of friction. In all these cases, there seems to be a veiy active cir- culation of blood in the capillary vessels of the bones and other structures of the joint. Much of the synovial membrane may be removed with the cartilages ; but the synovial folds and fimbriae (as they are called) which encircle the neck of the radius, and occupy the different fossae in front and behind the trochlea of the humerus, become unusually vascular and en- larged. In most of the cases we have examined, we have discovered what are called foreign bodies in the cavity of the joint. These we have found of all sizes, from that of a pea to that of a walnut. Some were seen hanging into the cavity of the articulation, being suspended by white slender membranous threads which seemed to be productions from the synovial sac; and some were loose in the joint: while, as to their structure, some were cartilaginous and bony. The number of these foreign bodies we have seen in the cavity of the elbow-joint we confess has astonished us, amounting in one case to twenty, in another to forty-five. In all these cases the vessels of the synovial fimbria; of the joint were in a highly congested state. The co-existence, therefore, of foreign bodies with such a condition of the membranes and their capillary vessels as these dissections elicited, cannot be too fully impressed on the mind of the practical surgeon, who is some- times solicited to undertake an apparently simple operation for their removal. Lastly, instead of the few scattered fibres external to the synovial sac, which, in this joint, when in a normal state, can scarcely be said to resemble even the rudiment of a capsule, we have found in these morbid specimens the thickness and number of ligamentous fibres so considerable, that the joint seemed to possess almost a com- plete capsular ligament. In Cruveilhier's Pathological Anatomy, Li- vraison No. 9, Plate 6, Figure 1, there is a gra- phic delineation of an elbow, illustrating many of the points here alluded to : he denominates the disease usure des cartilages, but it is quite sufficient to look at one of these cases, either in the living or the dead, to be satisfied that the disease does not confine itself to the cartilages of the joint, but that the arti- cular heads of the bones are also engaged; indeed, in many of our specimens, the bones of the elbow-joint are so much enlarged as to resemble at first sight the knee-joint; the shafts also of the ulna and radius are heavier and harder than natural,and their cancellated struc- ture no longer exists, the cells being so densely penetrated with phosphate of lime that the sections of these bones in several parts present the appearance of ivory. This account of the state of the elbow-joint produced by that slow disease called chronic rheumatism, is the result of many observations and dissections made specially by ourselves. We may also add that Mr. Smith, the able curator of the Museum of the Richmond Hospital, who has given equal attention to such investigations, has examined and preserved several specimens which verify the account here given of the anatomical cha- racters of this disease ; while, under the writer's own immediate charge in the House of Industry, are numerous living examples of, and sufferers from, this chronic disease, affecting the elbow- joint. In most of these cases, however, some of the other articulations are equally engaged.* ( R. Adams.) * [Since the preceding article was put to press, the Editor has been favoured with the following communication from the Author, which is too inte- resting to be omitted : '* Within these three days I met with a very singular case of congenital deformity of both elbows in a girl about eleven years of age. The radius could be felt to press forwards and backwards for the extent of an inch when it was rotated either in pronation or su- pination. These movements did not consist in a simple rotation of the radius on its longitu- ANIMAL ELECTRICITY. 81 ELECTRICITY, ANIMAL.— A power, or imponderable agent, possessed by and evolved from certain living animals, which enables them, independently of the operations of external agents on their structures, to pro- duce several of the phenomena exhibited by common and voltaic electricity, generated in inorganic matter. The animals so endowed, with which we are at present acquainted, are all fishes ; and the effect by which their power is most sensibly made known to us is the feeling of a shock, or momentary stunning, which is experienced in the hand that touches their surface. It is still doubtful whether the agent which produces this effect be absolutely identical with those which produce the various pheno- mena of common and voltaic electricity, ther- mo-electricity, &c; but the most recent re- searches on the subject render it probable that it is the same in its nature, although different in intensity. When Galvani discovered the possibility of exciting muscular contraction by establishing an external communication between the nerves and muscles by means of metals, he imagined that the contraction was produced by the sti- mulus of a peculiar agent (or fluid) existing in the nerves in a state of accumulation, which, being attracted by the metals, passed along them to the external surface of the muscles. The agent, which was supposed to remain latent in the nerves, was called by some " the nervous fluid," as it was imagined to be identical with that power which animates the nerves during life. Galvani seems to have entertained this notion. Other philosophers, avoiding a name derived from a theory, denominated the agent Galvanism. Afterwards it was called Animal dinal axis, but a real change of place of the upper extremity of the radius on the outer con- dyle of the humerus. The elbow was but slightly deformed, and all its motions were perfect ex- cept extension, which was not complete, but the girl had perfect rise of both arms and fore-arms, which were exactly similarly formed. The ra- dius seemed principally in fault, and the motions of the upper head corresponded much to the de- scription given of the subluxation. (Vide p. 74.) I was afforded an opportunity of examining the joints in consequence of the child having died of scarlet fever. Both joints were exactly alike. The radius was large, the great sigmoid cavity of the ulna was not half its usual size, and the coronoid process did not exist. The trochlea on the humerus, corresponding to the diminished sigmoid cavity, was one-half less than its natural size so that the lower extremity of the humerus bore so striking a resemblance to the condyles of the femur, when viewed posteriorly from the popli- teal space, that nobody could look at it without observing the striking resemblance in miniature of the humerus to the femur. There were fib ous bands representing the crucial ligaments, and all the fibres around were yellow and stronger than na tural. The annular ligament of the head of the radius was wider than natural but much stronger, and accounted for the passing to and fro of this head in pronation and supination. That the deformity was congenital no one can doubt : the appearance — the history —the exis- tence of the same malformation on both sides, all prove it." Dec. 12, 1836'.] VOL. II. Electricity. These views were supported by Valli, Carradori, Aldini, and Fowler. But, since Volta and others demonstrated that the contractions of the muscles in Galvani's expe- riments were owing to electricity developed by the contact of the metals employed, and not to any fluid pre-existent in the nerves, the term Animal Electricity has had its meaning changed. At present, most physiologists use it in the sense which is implied in the defini- tion given above. That is not called Animal Electricity which is generated by the friction of animal sub- stances one upon the other, or by the mere contact of animal tissues of dissimilar natures. The phenomena so developed have their source in common and voltaic electricity. They are phenomena exhibited by animals in common with inorganic matter. As the study of these, however, may ultimately lead to the elucidation of some points connected with the electricity of living fishes, they shall be noticed in the course of the following article. It is in the mode of its development that the chief peculiarity of Animal Electricity consists. None of the usual excitants of elec- tricity are concerned in it. There is no che- mical action, no friction, no alterations of tem- perature, no pressure, no change of form. The exercise of the animal's will, and the integrity of the nervous system, as well as of certain peculiar organs which exist in all the animals endowed with electrical power, seem to be alone sufficient for its evolution. The following are the systematic names of the electrical fishes at present known : — Torpedo nurke. unimaculata. llisso. murmoratu. Ditto. Galvanii. Ditto. Gymnolus electricus. Trichiurus electricus. Malapterurus electricus. Tetraodon electricus. The four species of Torpedo inhabit various parts of the Atlantic and Mediterranean. They were formerly regarded as constituting one species, (Raia Torpedo, of Linnaeus;) and now Dr. John Davy proposes to reduce them to two ; having satisfied himself (and in this he is supported by the opinions of Cuvier and of Rudolphi) that the T. marmorata and T. Gal- vanii are merely varieties of the same species, for which he suggests the name of T. diversi- color. It is known in Italy by the name of the Tremola. The other species (the Occhiatella of the Italians) Dr. Davy thinks would be better named T. oculata. Both pass in Malta under the term Haddayla. The first of these species (T. vulgaris, of Fleming,) occurs on the south coast of England, where it some- times attains a great size. Pennant mentions one which measured four feet in length and two and a half in breadth, and weighed fifty- three pounds. And Mr. Walsh describes an- other which was four feet six inches in length, and of the weight of seventy-three pounds.* * Phil. Trans. 1774. G 89 ANIMAL ELECTRICITY. Both species (Na§xii of Aristotle and Oppian) are abundant in some parts of the Mediter- ranean, and are frequently brought to the market of Rome. Off the west coasts of France, in Table-bay at the Cape of Good Hope, in the Persian Gulf and in the Pacific Ocean, the same, or at least nearly similar species are plentiful. They frequently form an article of food amongst the poorer class in the coast towns between the Loire and the Ga- ronne; but the electrical organs are carefully avoided, as they are supposed to possess some poisonous properties. The Gymnotus is found in several of the rivers of South America ; it was met with by Humboldt in the Guarapiche, the Oronoco, the Colorado, and the Amazon. The Malapterurus (Silurus, of Linnreus) occurs in the Niger, the Senegal, and the Nile; the Trichiurus in the Indian Seas ; the Tetraodon has been met with only on the shores of Jo- hanna, one of the Comoro Isles. According to Margrav* there is a kind of ray-shark on the coasts of Brazil, which possesses the power of giving shocks. He described the fish under the name of Paraque.f It is the Rhinobatus electricus of Schneider and other modern ich- thyologists. But in an examination which Rudolphi made of the fish in question, he found no structure resembling that peculiar organ which exists in all the well-known elec- trical fishes. No other naturalist has made the same observation as Margrav, so that the elec- trical power of this fish cannot be regarded as satisfactorily ascertained. In Maxwell's Ob- servations on Congo, mention is made of a large fish " like a cod," possessed of electrical powers, which was taken in the Atlantic Ocean. No such animal has yet come under the notice of any scientific observer. Certain insects seem to be possessed of some power re- sembling animal electricity in its effects, but few observations have hitherto been made on these. Reduvius serratus is one of the insects so endowed ; with regard to which an intel- ligent naturalist reports, that, on placing a living individual on the palm of his hand, he felt a kind of shock, which extended even to his shoulder; and that, immediately after- wards, he perceived on his hand red spots at the places whereon the six feet of the insect had rested.]: Margrav described a species of Mantis, a native of Brazil, which, on being touched, gave a shock felt through the whole body. According to the report of Molina§ and Vidaure,|| when the Sepia hexapodia is seized with the naked hand, a degree of numb- ness is felt, which continues for a few seconds. Alcyonium bursa, a native of the German Ocean, is said to have communicated to the hand a sensation like that of an electrical shock. It must be regarded as an extremely interest- * Hist, rerum Nat. Brasil. 1648. t The name Puraqua is used by Condamine in reference to the Gymnotus. X Kirby and Spence's Entomol. vol. i. 110. 6 Naturgesch. von Chili. S. 175. jj Gesch. des Kbnigr. Chili. S. 63. f Treviranus, Biologie. V. 144. ing fact that the electric fishes belong to genera widely removed, from one another in structure and habits, and yet that their own structure is not so peculiar as to prevent them from being arranged along with many other fishes posses- sing no degree of the same power and no vestige of a structure analogous to their own. As the fishes enumerated above have not all been examined with the same degree of atten- tion, we are ignorant of the extent to which they exhibit phenomena exactly resembling one another. But it is well ascertained that they all agree in possessing the power of commu- nicating a sudden shock to the hand which touches them. This shock causes a certain degree of temporary numbness not only in the finger which immediately touches the fish, but also in the hand, and sometimes even in the arm. The sensation produced has been com- pared by different experimenters to the shock felt on the discharge of a Leyden phial, dif- fering from it only in force. Hence the shock caused by an electrical fish is said to be pro- duced by a discharge of its electricity. The numerous facts relating to the phenomena which accompany or are connected with this discharge, which have been collected by the industry of the many observers of the last and the present age, who have devoted their atten- tion to the subject,* may be conveniently ar- ranged under the following heads: 1. the circumstances under which the discharge takes place : 2. the motions of the fish in the act of discharging : 3. physiological effects of the discharge: 4. magnetical effects of the discharge : 5. chemical effects of the dis- charge : 6. results of experiments on the transmission of the discharge through various conducting bodies : 7. the production of a spark and evolution of heat : 8. results of experiments in which the nerves, electrical organs, and other parts, were mutilated : 9. descriptions of the electrical organs in the several fishes which have been anatomized. I. Circumstances under which the discharge takes place. — Electrical fishes exert their pecu- liar power only occasionally, at irregular inter- vals, and chiefly when excited by the approach of some animal, or by the irritation of their surface by some foreign body. The discharge, both with regard to time and intensity, seems to be dependent on an exertion of the will. They discharge both in water and in air. Sometimes the discharge is repeated several times in close succession ; at other times, par- ticularly when the fish is languid, only one discharge follows each irritation. The inten- sity of the torpedo's discharge is generally greater when the fish is vigorous, becomes gra- dually less as its strength fails, and is wholly imperceptible shortly before death takes place ; but Dr. Davy has met with some languid and dying fish which exerted considerable electrical * Redi, Reaumur, Walsh, Ingenhousz, John Hunter, Cavendish, Bancroft, Spallanzani, Wil- liamson, Humboldt, Gay Lussac, Geoffroy, J. T. Todd, and Dr. John Davy, have all laboured in the same field of inquiry. ANIMAL ELECTRICITY. 83 power. No irritation has ever produced a dis- charge after death. The intensity of the elec- trical power seems to bear no relation to the size of the fish, at least after it has attained mature age ; small fish are almost always ac- tively electrical. The torpedo sometimes bears great irritation, even the firm grasp of a hand, without dis- charging. In these circumstances it writhes and twists itself about for some time, using strong efforts to escape, before it emits its electricity. In a few instances it has been found impossible by any means to excite even vigorous torpedos to discharge. Both Lace- pede and Reaumur handled and irritated the most lively torpedos, even while yet in their native element, without experiencing any shock. But generally the shocks are stronger when the skin of the fish is in any way irritated. All electrical fishes soon become exhausted and die, even in sea-water, when they are excited to give a continued succession of discharges. But fishes much exhausted by frequent dis- charges recover their electrical energy after a few hours' rest. The torpedo seems to possess electrical power even in the earliest periods of its existence. Spallanzani relates that he found within a female torpedo two living foetuses, which gave distinct shocks on being removed from their coverings. Dr. Davy, also, once received a sharp although not a strong shock, in extracting foetal fish from the uterine cavities of a dying torpedo. When the Gymnotus is grasped by the hand, the intensity of the discharge is moderate at first, but is increased if the pressure be conti- nued. The torpedo discharges whenever it is taken out of the water ; and Walsh found that a vigorous fish repeats the discharge as often as it is lifted out, and again on being re-im- mersed ; also that it gives more violent shocks in air than in water. Spallanzani found the shock to be more severe when the fish was laid on a plate of glass. The following observation, reported by Walsh, seems to prove that the Gymnotus can distinguish at some distance between substances capable of receiving and conducting its discharge, and those which can- not conduct ; and that (excepting when it is much irritated) it discharges only when con- ducting bodies are presented to it. Two wires were put into the water of the vessel in which a Gymnotus was swimming; these wires were of some length, and stretched; they termi- nated in two glasses filled with water placed at a considerable distance from each other. Whilst the apparatus remained in this state, and the circulation was of course interrupted, the animal did not prepare to exercise his power, but whenever any conducting substance filled the interval, and rendered the circle complete, it instantly approached the wires, arranged itself, and gave the shock. The same fish, according to the observations of Messrs. Humboldt and Bonpland, appears to have the power of transmitting its discharge in any direction it pleases, or towards the point where it is most sharply irritated ; and further, it seems to be able to discharge, some- times from a single point, at other times from the whole of its surface. Dr. Davy has s itis- fied himself that the Torpedo also has the power of discharging its electricity in any direction it chooses. The shock produced by the discharge of the Gymnotus is most severely felt when one hand seizes the head and the other the tail. When two persons take hold of a Gymnotus, the one by the head or by the middle of the body, and the other by the tail, both standing on the ground, shocks are felt, sometimes by one alone, sometimes by both. It has been ob- served that when metals are placed in the vessel or pond containing a Gymnotus, the fish appears much agitated, and discharges very frequently. II. Motions of the. fish in the act of dis- charging.— These have been particularly ob- served only in the Torpedo and Gymnotus. At the time of discharging, according to some ob- servers, the Torpedo generally becomes some- what tumid anterior to the lateral fins, retracts its eyes within their orbits, and moves its lateral fins in a convulsive manner. When the fish begins to lose its plumpness, after having given frequent shocks, " a little tran- sient agitation" is perceptible along the carti- lages which surround the electrical organs at the time of the discharge. Dr. Davy, how- ever, states that he has never seen the Torpedo of the Mediterranean retract its eyes at the time of discharging ; and that he has not been able to associate any apparent movement of the fish with the electrical discharge. The Gymnotus sometimes emits pie strongest discharges without moving any part of its sur- face in the slightest perceptible degree. But, at other times, it seems to arrange itself so as to bring the side of its body into a parallel with the object of its attack before discharging. When a small fish is brought near a Gymno- tus, it swims directly up to it, as if about to seize it ; on approaching close, however, it halts, seems to view the fish for a few seconds, and then, without making the smallest move- ment discoverable by the eye, emits its dis- charge ; should the small fish not be killed by the first, the Gymnotus gives a second, and a third shock, until its object is accomplished. It continues to kill a large number in close succession, if they be supplied to it, but it eats very few. III. Physiological effects of the discharge. — The effects of the discharge on man vary ac- cording to its intensity and the extent of the surface of the fish which is touched. A vigo- rous torpedo causes a momentary shock, which is felt through the arm even as far as the shoul- der, and. leaves a degree of painful numbness in the finger and hand, continuing for a few seconds, and then going off entirely. Some observers have compared the sensation pro- duced to that felt in the arm when the elbow is struck so as to compress strongly the ulnar nerve ; and others (even such as have been much accustomed to receive electric shocks) have declared the sensation to be extremely painful ; Gay Lussac and Humboldt say that G 2 84 ANIMAL ELECTRICITY. it is more so than the shock produced by the Leyden phial ; and Configliachi compares it to that caused by the contact of two poles of the voltaic pile. Ingenhousz thus describes his sensations under the discharge of the tor- pedo. " I took a torpedo in my hand, so that my thumbs pressed gently on the upper surface of the lateral fin, whilst my forefingers pressed the opposite side. About one or two minutes after I felt a sudden trembling in my thumbs, which extended no further than my hands ; this lasted about two or three seconds. After some seconds more, the same trembling was felt again. Sometimes it did not return in several minutes, and then came again at very different intervals. Sometimes I felt the trem- bling both in my fingers and my thumb. These tremors gave me the same sensations as if a great number of very small electrical bottles were discharged through my hand very quickly one after the other. Sometimes the shock was very weak, at other times so strong that I was very near being obliged to quit my hold of the animal."* Walsh ascertained that the same torpedo has the power of discharging in two different manners, so as to produce at one time the effect described by Ingenhousz as a trembling, and at another time a sharp instan- taneous shock closely resembling that produced by the discharge of a Leyden phial.f Accord- ing to Sir H. Davy, " whoever has felt the shocks both of the voltaic battery and of the torpedo must have been convinced, as far as sensation is concerned, of their strict ana- logy-"t Sometimes the torpedo buries itself in the sand left dry at ebb-tide; and it has occasionally happened, according to some naturalists, that persons walking across the sand, and treading upon the spot beneath which the electrical fish lay concealed, have received his discharge so fully as to be thrown down.§ The effects produced by the discharge of the Gymnotus are more severe. When it is touched with one hand, a smart shock is generally felt in the hand and fore-arm ; and, when both hands are applied, the shock passes through the breast. The discharges of large fish (they grow to the length of twenty feet in their native rivers) sometimes prove sufficient to deprive * Phil. Trans. 1775, 2. t Phil. Trans. 1773, 467. % Phil. Trans. 1829, 15. § The experience of Dr. Davy would lead us to call in question the possibility of such an occurrence ; for he has always found it necessary to touch the opposite surfaces of the electrical organs or organ to receive the torpedo's shock. He has irritated torpe- dos very frequently by pressing with the finger on different parts of the back, but however much the fish were irritated he never had any sensation re- ferable to the passage of the electricity. In corro- boration of his opinion that the fish cannot give a shock excepting the two opposite surfaces of its electrical organs be connected by conductors, Dr.D. states that when one surface only is touched and irri- tated, the fish themselves appear to make an effort to bring, by muscular contraction, the border of the other surface into contact with the offending body. This" is done even by fcetal fish. Phil. Trans. 1834.' men, while bathing, of sense and motion. Fermin found that a strong one had power to give a shock to fourteen persons at the same time ; and other experimenters have seen twenty- seven persons simultaneously receive its shock. Humboldt states that, having placed his feet on a fresh Gymnotus, he experienced a more dreadful shock than he ever received from a Leyden phial, and that it left a severe pain in his knees and in other parts of his body, which continued for seveial hours. Sometimes the discharge occasions strong contractions of the flexor muscles of the hand which grasps the fish, so that it cannot be immediately let go ; and then, the shock being repeated still more severely, painful sensations are experienced thoughout the whole body, and headache with soreness of the legs remains for some time after.* Paralytic affections, as well as giddiness and dimness of sight, are said sometimes to have followed the reception of strong discharges.f It is stated by some observers that there are men who are as insusceptible of the shocks of electrical fishes as others are of those from the Leyden phial ; and that women affected with nervous diseases are seldom conscious of receiving the discharge. Kaempfer asserted} that, by sup- pressing respiration for a short time, any man may render himself insensible to the torpedo's discharge; but this has been disproved by Walsh and other observers. Regarding the effects of the discharges of the other electrical fishes, we know very little. The shock given by the Malapterurusof the Nile and Niger (Silurus, Linn.) is said to be more feeble than that of the Torpedo, and yet very painful, attended with trembling, and followed by soreness of the limbs. In attempting to take an individual of Tetraodon electricus in his hand, Lieutenant Paterson (its discoverer) received so severe an electrical shock that he was obliged to quit his hold. The effects of the discharge of the Gymnotus on the larger animals cannot be better illustrated then by the account which Humboldt has given of the method of capturing the fish adopted by the South American Indians. This method consists in irritating the fish by driving horses into the pools which it inhabits. It directs its electricity in repeated discharges against these horses until it becomes exhausted, when it falls an easy and harmless prey into the hands of the fishermen. Humboldt saw about thirty wild horses and mules forced into a pool con- taining numerous Gymnoti. The Indians sur- rounded the banks closely, and being armed with harpoons and long reeds, effectually pre- vented the escape of the horses. The fishes were aroused by their trampling, and, coming to the surface, directed their electrical discharges against the bellies of the intruders. Several horses were quickly stunned, and disappeared beneath the surface of the water. Others, ex- hibiting signs of dreadful agony, hurried to the bank, with bristled mane and haggard eye, but * Bryant, Trans. Amer. Soc. ii. 167. t Flagg, do. ii. 170. - I X Amoen. Exot. 514. ANIMAL ELECTRICITY. 85 there they were met by the wild cries and violent menaces of the Indians, which forced them again to enter the water. And when, at last, the sur- vivors were permitted to leave the pool, they came out enfeebled to the last degree, and their benumbed limbs being unable to support them, they stretched themselves out upon the sand completely exhausted. In the course of five minutes two horses were drowned. By degrees, the discharges from the Gymnoti becoming less intense, the horses no longer manifested the same signs of agony, and the wearied fishes ap- proached the margin of the pool, almost lifeless; and then they were easily captured by means of small harpoons attached to long cords. The fishes left in a pool thus disturbed were found scarcely able to give even weak shocks at the end of two days from the time of their combat with the horses. Humboldt concluded from what he saw and heard, that the horses which are lost in the course of this singular fishery are not killed, but merely stunned, by the dis- charge. Their death is occasioned by the con- sequent submersion. In this way many mules are destroyed in at- tempting to ford rivers inhabited by the Gymno- tus. So great a number of mules were thus lost within the last few years at a ford near Uritucu, that the road by it was entirely abandoned. When small fishes receive the discharge of a Gymnotus, they are immediately stunned, turn upon their backs, and remain motionless. They however, for the most part, recover after being removed to another vessel. Reaumur reports that he once saw a duck killed by the repeated discharges of a torpedo ; but both Ingenhousz and Dr. John Davy kept small fishes in the same vessel with torpedos, without observing that the former showed any symptoms of suffering from the shock of the latter. Humboldt saw one Gymnotus receive the discharge of another with- out giving any evidence of feeling it. Galvani, having placed some frogs' thighs, skinned, on the back of a torpedo, saw them convulsed when the fish was excited to discharge. It is said that the discharge of the torpedo is used medicinally by the Arabians of the present day, particularly in fevers. The patient is placed naked on a table, and the fish applied to all the members of the body in succession, so that each should receive, at least, one shock. This treat- ment causes rather severe suffering, but enjoys the reputation of being febrifuge. IV. Magnetical effects of the discharge — Schilling asserted that he had seen the magnetic needle set in motion by the discharge of a Gym- notus ;* also, that the fish was attracted by a magnet, and adhered to it ; and that it became so languid when detached from the magnet, that it gave no shock when irritated. Ingenhousz, Spallanzani, Flagg, Humboldt, and Bonpland obtained no such results in repeating the expe- riments of Schilling. Professor Hahn of Ley- den suggests that the fish examined by Schilling may have been coated with particles of ferrugi- nous sand, which frequently forms the beds of the American rivers inhabited by the Gymnotus ; * Mem. de l'Acad. de Berlin, 1770. and that these, adhering to its glutinous skin, may have given rise to the phenomena observed by Schilling. In quoting the contradictory statements of the above-mentioned observers, Treviranus remarks,* " it is a striking circum- stance that so good an observer as Schilling was should have been convinced that he saw such magnetic phenomena in connexion with the fish, and still more remarkable is it that Humboldt and Bonpland should have found a belief in the possession of magnetic properties by the Gymnotus prevalent amongst the inhabitants of the Savannas of Caraccas." Sir Humphry Davy passed many strong dis- charges from a torpedo through the circuit of an extremely delicate magnetic electrometer, with- out perceiving the slightest deviation of, or effect on, the needle. He explained this negative result by supposing, that the motion of the electricity in the organ of the torpedo is in no measurable time, and that a current of some continuance is necessary to produce the devia- tion of the magnetic needle.f Under more favourable circumstances than those in which Sir H. Davy investigated the properties of the electricity of the torpedo, Dr. John Davy re- sumed the enquiry at Malta, and ascertained, in the most satisfactory manner, that animal elec- tricity is capable of producing magnetic effects. He not only saw the needle of a magnetic elec- trometer very much affected by the discharge of a torpedo, but he found needles, previously free from magnetism, converted into magnets by the same. In one experiment, he placed eight needles within a spiral, formed of fine copper wire, one inch and a half long, and one tenth of an inch in diameter, containingaboutonehundred and eighty convolutions, and weighingfour grains and a half. A single discharge from a torpedo, six inches long, having been passed through this, the contained needles were all converted into magnets, each one as strong as if only one had been used. It was found that the ends of the needles which were nearest the ventral sur- face of the fish had received southern polarity, and of course the other extremities northern po- larity. The discharges from fish, only four hours after they were taken from the uterine cavities of their mother, were sufficiently strong to magne- tize needles through the medium of a spiral, al- though but feebly. The same kind of result was obtained with the multiplier; the needle of which, when subjected to a torpedo's discharge, indicated that the electricity of the dorsal surface corresponded with that of the copperplate of the voltaic pile, and the electricity of the ventral surface with that of the zinc plate. In 1827, before Dr. Davy performed his ex- periments, similar magnetic effects were observed by means of the multiplier, by MM. De Blainville and Fleuriau, at La Rochelle. They * Biologie, v. 145. t Phil. Trans. 1829. 16. Similar experiments were made with the discharge of the Gymnotus by Messrs. Rittenhouse and Kinnersly with the same results. They saw no effect produced on the elec- trometer. Philadelphia Med . and Phys. Journal, i. 15. 86 ANIMAL ELECTRICITY. thrust into the electrical organ of a torpedo the two needles which terminate the wires of Schweigger's multiplier, and immediately saw the magnetic needle describe more than half a revolution.* V. Chemical effects of the discharge. — It does not appear that any observer before Sir H. Davy attempted to ascertain what chemical effects the discharge from electrical fishes is capable of producing. But Sir Humphry obtained only negative results. He passed the shocks of the torpedo through the unterrupted circuit made by the silver wire through water, without being able to perceive the slightest de- composition of the water.f Dr. John Davy, however, has obtained decisive evidence of chemical agency being exerted by animal elec- tricity. The fishes which he made use of in his experiments were more recently taken from the sea, and were, consequently, more vigorous than those which were the subjects of Sir Humphry's observations; and it was, probably, owing to this circumstance that the results which he obtained were different from those of his brother's experiments. By means of golden wires, one of which was applied to the upper surface of the fish, and the other to its under surface, Dr. Davy passed the discharge from a torpedo through solutions of nitrate of silver, common salt, and superacetate of lead, and found that all were decomposed. The decomposition of the superacetate of lead was effected only when the fish seemed to put forth all its energy, after being much irritated. J From the solution of nitrate of silver, the metal was precipitated only on the wire connected with the ventral surface of the fish. When platina wires were used, and plunged into nitric acid, gas was given off only from that in con- nexion with the dorsal surface. A solution of iodide of potassium and starch having been subjected to the discharge conveyed along the platma wires, had the iodine in combination with the starch precipitated from it on the wire from the upper surface.§ By the same dis- charges which produced these chemical effects, the needle in the galvanometer was moved, the spirit in the air-thermometer was raised, and needles in the spiral were magnetized. VI. Results of experiments on the transmis- sion of the discharge through various conduct- ing bodies. — Almost all bodies which are con- ductors of common and voltaic electricity con- duct also the discharge of electrical fishes ; and those which are non-conductors with regard to the former are the same with regard to the latter. But the discharge of the torpedo, when feeble, does not pass along even good conductors ; and this circumstance has given rise to some dis- crepancy between the statements of different observers. Walsh received the torpedo's dis- charge through iron bolts and wet hempen cords. The French fishermen declare that they sometimes receive shocks through nets, while * Pouillet, Plem. de Phys. i. 773. t Phil. Trans. 1829. t Phil. Trans. 1832. § Phil. Trans. 1834. the fish is twelve feet distant from their hands. But Humboldt and Gay Lussac state that they received no shock when they touched the fish with a key or any other conducting body;* further, that when they placed the fish upon a metallic plate, so that the inferior surface of its electric organ touched the metal, the hand which supported it felt no shock : and they concluded from their experiments that the torpedo could not transmit its discharge through even a thin layer of water ; although they found that when, two persons applied each one hand to the fish, and completed a circuit through their own bodies by means of a pointed piece of metal held in the other hand, and plunged into a little water placed upon an insulating body, both felt the shock. In one instance Dr. Davy received the torpedo's shock through water, but his hand was within a very short distance of the fish. Walsh transmitted the torpedo's discharge through a chain of eight persons, who com- municated with one another only by water con- tained in basins, in which their hands were immersed. And the same observer also found that when a torpedo was touched with a single finger of one hand, while the other hand was held in the water at some distance, shocks were distinctly felt in both hands. Numerous observations made on the Gymnotus leave no doubt with regard to the passage of its discharge through water. If a person hold his finger in the water several inches (some say even ten feet) distant from the fish, and another person touch it, both receive shocks equally severe. Dr. Williamson found that a person holding his finger in a stream of water, running from a hole made in the bottom of a wooden vessel in which a Gymnotus was swimming, very dis- tinctly felt all the discharges given by the fish. The discharge from the Gymnotus passes through a chain of ten persons, so that they all seem to feel the shock in the same degree. It is con- ducted by iron rods several feet in length. It does not pass through air, interposed between metallic conductors, until these are brought within about one-hundredth of an inch of each other. So far as they have been examined, the phe- nomena presented by the discharge of the Silurus have been found to be nearly the same as those just detailed. VII. The production of a spark, and evolu- tion of heat. — No observer has hitherto seen light emitted from the body of any electrical fish at the time of the discharge ; but, by artificial arrangements, some have succeeded in pro- ducing sparks in the course of the circuit de- scribed by the discharge. In 1792, Gardini saw a spark from a torpedo's discharge, in the course of his repeating some of Walsh's experiments. And in 1797, Galvani obtained a small spark, visible only with the aid of a lens, from a torpedo ; but it does not appear that any other observer has been equally successful with regard to this fish. Very recently, Dr. Davy has directed his attention particularly to this point, and, although he used active fish, and took * Ann. de Chimie, t. lxv. 15. ANIMAL ELECTRICITY. 87 every possible precaution, he could neither, in the light, detect the slightest indications of the passage of electricity through even very small intervals of air, nor observe a spark in the dark. He was equally unsuccessful in using an elec- troscope formed on the principle of Coulomb's, which displayed sparks when touched either with a small rod of glass slightly excited, or of sealing-wax. He varied the trials, using highly rarefied air at ordinary temperatures, and also condensed air deprived of moisture, with the same negative result. He insulated the fish on a plate of glass, wiped its margin dry, and besmeared it with oil, but no spark could be procured. Dr. Davy was more successful in obtaining indications of the evolution of heat during the torpedo's discharge. He used Harris's electro- meter, and saw proof of an elevation of tem- perature in the motions of the fluid in the air- thermometer; thus corroborating the prediction of Dr. Faraday, who was previously convinced that, by means of this instrument, the evolution of heat by animal electricity would be made evident. Dr. Davy made several experiments with the view of ascertaining whether very fine platina wire might not be ignited in the passage of the electricity of the torpedo, but never witnessed the expected effect. Upon this he remarks, "This want of ignition may, at first view, seem contrary to the effect on the ther- mometer ; but perhaps it ought not to be con- sidered so, taking into account the rapid man- ner in which the heat evolved in the fine pla- tina wire must be carried off by the adjoining compound wire of platina and silver."* From the discharge of the Gymnotus, Walsh, Fahlberg, Guisan, and other observers of the last century, obtained sparks. Walsh attached a thin sheet of pewter to a plate of glass, cut a very fine slit in it, and then passed the discharge along the metallic sheet, the fish being at the time out of the water. A spark was very dis- tinctly seen at the margins of the slit. Fahlberg of Stockholm used the same kind of apparatus, but with gold leaves instead of pewter, and placed the margins of these about a line apart. Dr. Williamson fixed two brass rods in a frame, and brought their points to within one-hundredth of an inch of each other, but, although the dis- charge of the gymnotus passed from one rod to the other through the intervening air, there was no spark. Humboldt watched an active Gym- notus for a long time during the night, and irritated it so as to obtain from it many sharp discharges, but he saw no spark. VIII. Results of experiments in which the nerves, electrical organs, and other parts were mutilated. — The general result of these experi- ments is, that destruction of the communications between the electrical organs and the nervous centres is followed by annihilation of the power of discharging. According to Mr. Todd, (whose experiments were made on the torpedo at the Cape of Good Hope,) it is necessary to cut through all the nerves going to the electrical organs to destroy * Phil. Trans. 1834. their peculiar powers. He cut through all on one side, and some on the other, but still shocks were given. He also lacerated the organs themselves extensively, without destroy- ing the discharging power. Mr. Todd found that fishes in which all the electrical nerves had been cut appeared more vivacious after the operation than before it, and actually lived longer than others not so injured, but which were excited to discharge frequently.* In repeating Mr. Todd's experiments, Dr. Davy obtained very similar results; but he mentions that "when a small portion of brain was accidentally left, contiguous to the elec- trical nerves of one side, and with which they were connected, the fish, on being irritated, gave a shock to an assistant, who grasped the corresponding electrical organ. "f Spallanzani found that the torpedo loses its power of giving shocks after the aponeurotic covering of the electrical organs is removed ; but that the cutting out of the heart does not lessen this power until the animal life begins to suffer from the loss of blood. Humboldt cut a Gymnotus through the mid- dle of the body transversely, and found that the anterior portion alone continued to give shocks. Experiments of this kind have not yet been performed on the Silurus ; but, judging from the structure of the organs in this fish, we have every reason to expect that the results of such experiments on it would be the same. While we would not be understood to sanction the wanton repetition of experiments such as these, which cannot but be productive of much suffer- ing to the subjects of them, we must yet repeat here the suggestion recently made by Professor Muller of Berlin with regard to future experi- ments on the Gymnotus and Silurus. He points out how very desirable it is to ascertain whether the double organs of these fishes act as opposite electromotors, which might be determined by cutting out one organ from either side, and then exciting the fish to discharge. The same dis- tinguished physiologist remarks that if he had an opportunity of experimenting on the torpedo, his first experiment should be, after having cut through the nerves going to the electrical organs, to irritate their cut extremities, still in connexion with the organs, with mechanical and galvanic stimulants, with the view of discovering whether these would excite the organs to discharge their electricity.^ IX. Anatomy of the electrical organs. — The experiments referred to in the former section sufficiently demonstrate that the manifestation of the peculiar power possessed by electrical fishes depends on the integrity of the connexion between their nervous centres and certain organs of a peculiar structure, which have been named the electrical organs. These have been particularly examined in the Torpedo, Gymnotus, and Silurus, by several anatomists, and no doubt is entertained that they, together * Phil. Trans. 1816. f Phil. Trans. 1834. 120. I Handbuch der Physiol, des Menschen. Co- blenz. 1833. 38 ANIMAL ELECTRICITY. with their large nerves, are the sole means coverings are discovered investing the electrical employed in bringing this mysterious agent organs. The outer one has longitudinal fibres, under the control of the animal's volition, which are rather loosely adherent, and, around They are therefore well worthy of an attentive the margins of the organs, seem to inosculate examination. with the skin. The inner fascia is of consider- 1. The electrical organs in the torpedo. — able density, forms the immediate tunic of the The torpedo is a flat fish, possessing the same electric columns, and sends processes down general appearance and structure as the rays, between them to form their partitions. Through- and classed along with them in zoological sys- out their whole extent, the essential part of the terns. The electrical organs occupy a large electrical organs is formed by a whitish soft Fig. 47. Upper surface of electrical organ of left side. A, common integuments. B, hranchial opening. C, eye. D, situation of the gills. E E, skin dis- sected off from the electrical organ, and turned outwards. F, part of the skin which covered the gills, G G, the upper surface of electrical organ. part of the broad expansions of the body, which in the other allied fishes are formed only by the lateral fins. They form two sepa- rate masses, one on either side of the head and gills, extending outwardly to the cartilaginous margins of the great fins; and, posteriorly, to the cartilage which separates the thoracic from the al dorainal cavity. Their form and the honey-comb embossments of their surfaces can be distinguished through the skin both of the dorsal and ventral aspects. The common inte- guments being removed, two strong fascial pulp, divided into numerous pentagonal prisms by the fascial processes just mentioned. These lie close together, parallel with one another, and perpendicularly between the dorsal and ventral surfaces of the fish, so that their extre- mities are separated from these surfaces only by their fascial and the common integuments. YVhen these are removed, the columns present something of the appearance of a honey-comb. The columns are longest next to the head and gills, and thence gra lually diminish outwardly, until, on the external margin, they are only ANIMAL ELECTRICITY. 89 about one-sixth of the length of the internal ones. In a fish described by John Hunter,* of which the whole electrical organ was about five inches in length, the longest column was about one inch and a half, and the shortest about one-fourth of an inch in length. In the same fish the average diameter of each column was about two-tenths of an inch. In a fish from the Mediterranean, thirteen inches and a half in length, and about seven inches in breadth, (which, through the kindness of Dr. Allen Thomson, we have had an opportunity of examining in detail,) the length of the longest columns is one inch, and that of the shortest about three-tenths of an inch. Most of these columns are either irregular pentagons, or irregular hexagons ; a few are nearly tetra- gonal. They are united to one another by short but strong fibres, and by a reticular expansion of tendinous threads spread through them. Their number varies considerably ac- cording to the age of the fish. Hunter con- jectured that a few new columns are added every year to the circumference of the organ. In one of the largest fish that has yet been particularly examined, which was four feet and a half in length, the number of columns in one electrical organ was 1182. Mr. Hunter found 470 in each organ in a fish of ordinary size. Mr. Hunter described each column as being divided into numerous distinct compart- ments by delicate membranous partitions, placed horizontally, at very short distances from each other. The interstices between them appeared to him to contain a fluid. He found the partitions in several places adhering to one another by bloodvessels; and all, throughout their whole extent, attached to the inside of the column by a fine cellular membrane. In a column of one inch in length, he reckoned 150 partitions, and it appeared to him that their number is the same within the same space in all the columns.f Hence, he thought it likely that " the increase in the length of a column, during the growth of the animal, does not enlarge the distance between each partition in proportion to that growth, but that new partitions are formed and added to the extre- mity of the column from the fascia." The partitions are covered with fine network of arteries, veins, and nerves. According to Hunter, " they are very vascular." He described the numerous arterial branches which ramify on the walls of the columns as " sending in- wards from the circumference all around, on each partition, small arteries which anastomose upon it, and passing also from one to the other, unite with the vessels of the adjacent parti- tions." The partitions themselves are so deli- cate as not to admit of being satisfactorily examined in the fresh fish : (all Hunter's obser- vations were made upon fish that had been preserved in spirits, by which, doubtless, the delicate membranes were rendered more opaque, and therefore more easily visible.) In point * Pl.il. Trans 1773, 481. t Desmotilins and Majenriie say that they found only seven or eight partitions in each column. Anat. des Syst. Nerv. ii. 378. of fact, Dr. Davy has never seen them in the course of the numerous dissections which he has made of the electrical organs in fish recently taken; whereas, in specimens sent hither by him, preserved in spirits, Dr. Allen Thomson and the writer of this article have satisfactorily ascertained their existence and structure as described by Hunter. Dr. Davy says, " when I have examined with a single lens, which magnifies more than 200 times, a column of the electrical organs, it has not exhibited any regular structure ; it has appeared as a homo- geneous mass, with a few fibres passing into it in irregular directions, which were probably nervous fibres."* However, after having im- mersed the organs in boiling water, Dr. Davy has occasionally seen something like a lami- nated structure within the column. Rudolphi satisfied himself of the division of the columns by membranous partitions, and further, that each partition is supplied with a distinct nerve.-f- In a memoir on the comparative anatomy of the Torpedo, Gymnotus, and Silurus, Geoff'roy described! the columns as being filled with a semifluid matter composed of gelatine and albumen. A lar«e quantity of fluid enters into the composition of the general mass of the elec- trical organs. Dr. Davy has found that they lose more by drying than any other part of the fish — nearly 93 per cent.; while the soft parts in general, including the electrical organs, lose only 84.5 per cent,§ He believes that the fluids of the organs hold various substances in solution, but the exact nature and proportions of them have not been ascertained. We are indebted to the same indefatigable observer for an ac- count of the specific gravity of the electrical organs. He found it to be very low compared with that of the truly muscular parts of the fish, — namely, 1.020, to water as 1.0G0, while that of a part of the abdominal muscles of the same full-grown fish was 1.058, and of the dorsal muscles 1.065. In a fish eight inches long, five inches across the widest part, and which weighed 2065 grains entire, the electric organs together weighed 302 grains, the liver only 105 grains. No contraction has ever been seen in the electrical organs of living fish under the stimu- lus of the strongest excitants, not even under that of galvanism ; so that, although what appear to be tendinous threads are spread amongst and over the columns, we have no reason to suppose that any muscular tissue enters into their composition. But, in all directions, they are exposed to the pressure of * Phil. Trans. 1832. 259. t Ahhandl. der Acad, der Wissensch. in Berlin. 1820. 224. t Ann. dn Mus. TvTo. 5. § The sma'lest torpedo employed hy Dr. Davy in his experiments weighed 410 grains, and con- tained only 48 grains of solid matter; its elec- trical organs weighed 150 grains, and contained only 14 grains of solid matter; yet this small mass gave sharp shocks, converted needles into magnets, affected distinctly the multiplier, and acted as a chemical agent. " A priori, how inconceivable that these effects could be so produced'." 00 ANIMAL ELECTRICITY. strong muscles, such as are plainly designed to compress them. Some of these are inserted into the marginal cartilages of the fins; and there is a set of very powerful ones, arranged in a cruci- form manner on the ventral surface, so placed as to compress the electrical organs most strongly during their contraction. Dr. Davy remarks, " It is only necessary to compare these muscles as they exist in the torpedo with the same in any other species of ray to be convinced that they are adequate to, and designed for, the compression of the batteries." Some observers, as John Hunter, state that a large proportion of blood circulates through the electrical organs. Girardi found the torpedo much more full of blood than the other rays.* But Dr. Davy says, that there are very few vessels containing red blood in the organs them- selves; although their tegumentary coverings and the adjoining mucous system are highly vascular. The arteries of the organs are branches from the arteries of the gills ; their veins run between the gills direct to the auricle. The temperature of the electrical organs is not at all higher than that of other parts of the fish. All anatomists who have examined the torpedo have had their attention much arrested by the great size of the nerves distributed to the electri- cal organs. These consist of three principal trunks, all arising immediately from the cerebro- spinal system. The two anterior trunks are re- garded by Desmoulins and Majendie f as portions of the fifth pair of nerves, and the third as a branch of the eighth pair. But the first electrical nerve seems to have an origin altogether distinct from the root of what is unquestionably the main portion of the fifth pair, although it certainly is in very close proximity with it, and, in passing out of the cranium, the two nerves seem to be in some degree united for a short space. Immediately beyond this point of union, the electrical nerve sends a soft twig to a small cavity within the adjoining cartilage, (which Dr. Davy thinks is the ear,) and then divides into three small branches, and two large ones. One of the small branches goes to the gills, another to the neighbouring muscles, and the third to the mouth. The first of the large branches runs along the outer margin of the electrical organ, advancing first anteriorly, then going round to the posterior part of its circumference, and losing itself in the mucous glands of the tegu- mentary system, without sending a single twig into the electrical organ itself. The other great branch is inferior to the former in position, but much more voluminous ; it enters the electrical organ, and is ramified through its anterior third part, passing between its columns, and giving off numerous twigs for the supply of the walls of the columns, and the partitions, on which it terminates; some of which pass even into the gelatinous matter with which the columns are filled. This branch, from its very origin, has all its fibres separated, isolated, and parallel, held together only by cellular tissue, which also forms a kind of membranous sheath around * Mem. della Soc. Ital. iii. 553. t Anat. Comp. des Syst, nerv. the nerve. Just as it reaches the organ, it is divided horizontally into two portions, one of which runs near the upper surface, the other on the plane between the lower and middle thirds of the thickness of the organ. When examined with a high magnifying power, the minute branches of the electrical nerves present a dotted appearance, showing as if the medullary substance were arranged within the sheath, not in a continuous line, but in a succession of small portions with a little space between each.* The second electrical nerve rises a little be- hind the former. After leaving the cranium, it divides into two large branches, which, with the exception of a few twigs which go to the gills, are wholly distributed in the middle third of the electrical organs, in the same manner as the first pair. The third electrical nerve arises'from the brain close to the second, from which, however, it is separated by a thin cartilaginous plate. The greater portion of it goes to the electrical organ, and is distributed through its posterior third. It also supplies part of the gills, the gullet, the sto- mach, and the tail. Dr. Davy says it appeared to him that the branch of this nerve which goes to the stomach is the principal nerve of that organ : it is spread over its great arch.f The same observer also points out as deserving of particular attention, a very large plexus of nerves formed by a union of the anterior and posterior cervical nerves, of the former of which there are seventeen on either side, and only fourteen of the latter. This plexus presents itself as a single trunk just below the transverse cartilage that divides the thoracic from the abdominal cavity. It sends a recurrent branch to the muscles and skin of the under surface of the thorax; but the larger portion is distributed upon the pectoral fin and the neighbouring parts. The motive and sentient powers of the muscles and integuments connected with the electrical organs seem to depend on this plexus. The only other peculiarity of structure in the torpedo which can be supposed to be in any way connected with its electrical power, is in the system of mucous ducts, which is much more fully developed in it than in any other ray with which we are acquainted. It consists of numerous groups of glands arranged chiefly around the electrical organs; and of tubes con- nected with these, having strong and dense coats, filled with a thick mucus secreted by the glands. The tubes open chiefly on the dorsal surface of the skin, and pour out the mucus, * Dr. John Davy, Phil. Trans. 1834. t On this subject, Dr. Davy remarks — *' It is an interesting fact that the nerves of the stomach are derived from those supplying the electrical organs. Perhaps superfluous electricity, when not required for the defence of the animal, may be directed to this organ to promote digestion. In the instance of a fish which I had in my possession alive many days, and which was frequently excited to give shocks, di- gestion appeared to have been completely arrested; when it died, a small fish was found in its stomach, much in the same state as when it was swallowed — no portion of it had been dissolved." ANIMAL ELECTRICITY. 91 Fig. 48. The right electrical organ divided horizontally at the place where the nerves enter, the upper half being turned outwards. A A, The first or anterior electrical nerve. B B, The second or middle nerve arising behind the gill. C C, The anterior branch of the third nerve arising behind the second gill. D D, The posterior branch of the third nerve arising behind the third gill. which, probably, serves as a medium of com- munication between the electrical organs ; being, apparently, a better conductor of electricity than either the naked skin or salt water* With regard to the development of the elec- trical organs, it appears that, in the earliest stages of foetal growth, they cannot be seen. In a foetus of about seven-tenths of an inch in length, Dr. Davy found neither electrical organs nor fins. In another, more than one inch long, the organs were beginning to appear, and the roots of the electrical nerves were visible, although the brain could not be seen. In this stage, the external branchial filaments • were about six-tenths of an inch in length, and pre- * Davy, Phil. Trans. 1832. Also Annates du Mus. no. v., in which E. Geoffroy endeavoured to show that the common mucous system of rays is absent in the torpedo, and that its place is supplied by the columns of the electrical organs, which he believed to be analogous to the mucous ducts. sented a very remarkable appearance. In a foetus of two inches and a half long, the electrical organs were distinctly formed, and the branchial filaments still long. These filaments Dr. Davy supposes to be destined to absorb matter for the formation of the electrical organs, and, perhaps, the gills and adjoining mucous glands. They are most numerous and of greatest length while the electrical organs are forming, appearing just before these organs begin to be developed, and being removed when they are tolerably com- plete.— In no other allied fishes is there the same " elaborate apparatus of filaments ;" where they do exist, they are less numerous and very much shorter. 2. The electrical organs in the Gymnotus. — This fish has a general resemblance in form to the common eel. Its electrical organs occupy nearly one-third of its whole bulk. They are formed by two series of tendinous membranes ; one of which consists of horizontal plates, run- 92 ANIMAL ELECTRICITY. ning from the abdominal cavity towards the tail, placed one above another with short distances between them ; the other of perpendicular plates, forming, along with the other series, small quad- rangular cells, which are filled with a semi-gela- tinous transparent substance. This structure is divided longitudinally into two pairs of distinct organs, one considerably larger than the other. The greater pair (k k, fig. 49) lies above the other, and immediately beneath the long mus- cles of the tail. They are separated from one another by part of these muscles, by the air- bladder, and by a central membranous partition. They occupy a large portion of the lower and lateral parts of the body, and are covered exter- nally only by the common integuments. The smaller pair are covered also by the muscles of the caudal fin. Both pairs of organs are some- what angular in their transverse section, trun- cated anteriorly, tapering towards the tail. In theGymnotus dissected by John Hunter,* which was about two feet four inches long, the large Fig. 49. The surface of the electrical organs of the Gymnotus, on the right side, after removal of the integuments. a, the lower jaw. b, the abdomen, c, anus, d, pectoral fin. e, dorsal surface of fish. //, anal fin. gg, skin turned back, h h, lateral muscles of the anal fin turned back with the skin, to expose the small electrical organ, i, part of this muscle left in its place, k k, the large electrical organ. / I, the small electrical oiyan. m m, the substance which divides the large organ from the small, n, a space from which the partition is removed. organ of one side was about one inch and one quarter in breadth at its thickest part, and in this space there were thirty-four longitudinal septa. (In a specimen examined by Dr. Knox, there were thirty-one of these septa.f) The smaller organ in the same fish was about half an inch in breadth, and contained fourteen septa, which were slightly waved. The per- pendicular or transverse membranes are placed much more closely toge- ther than those of the other series. John Hunter and Dr. Knox counted two hundred and forty of them in an inch. They are of a softer texture than the longitudinal plates. It ap- pears probable (as Hunter suggested) that these septa, longitudinal and transverse, answer the same purpose as the columns in the torpedo. La- cepede calculated that the discharg- ing surface of these organs in a fish four feet in length is, at least, one hundred and twenty-three square feet in extent; while in a torpedo of ordi- nary size, the discharging surface is only about fifty-eight feet square. The nerves of the electrical organs of the Gymnotus are derived from the spinal marrow alone. They are very large and numerous, and are divided into very fine twigs on the cells of the organs. Dr. Knox counted fifteen nervous branches distributed to each inch of the organ. He describes them as being flattened like the ci- liary nerves of Mammalia. Each * Phil. Trans. Ixv. 1775. t Edin. Journ. of Science, i. 96. 1824. A transverse section of the Gymnotus. a, the surface of the side of the fish, b, the anal fin. c c, cut ends of the dorsal muscles, d, cavity of the air-bladder. e, body of the spine. /, spinal marrow, g, aorta and vena cava, h h, cut ends of the two large electrical organs, i i, cut ends of the two small organs, k, partition between the two organs. ANIMAL ELECTRICITY. 93 nerve is, for the most part, divided into five distinct branches before entering the electrical organs ; and these are again subdivided into, at least, as many branches as there are longi- tudinal septa. Rudolphi describes a nerve formed from branches of the fifth pair and sympathetic, which runs beneath the lateral line, over the surface of the electrical organs, but does not enter them. This has, by some, been supposed to be an electrical nerve, but without sufficient reason.* 3. The electrical organs in the Silurus. — The only organ that can be regarded as con- nected with the electrical function in this fish is a thick layer of dense cellular tissue, which completely surrounds the body immediately beneath the integuments. So compact is it that, at first sight, it might be mistaken for a deposit of fatty matter. But, under the mi- croscope, it appears to be composed of ten- dinous fibres, closely interwoven, the meshes of which are filled with a gelatinous substance. This organ is divided by a strong aponeurotic membrane into two circular layers, one outer, lying immediately beneath the corion, the other interna], placed above the muscles. Both or- gans are isolated from the surrounding paits by a dense fascia, excepting where the nerves and bloodvessels enter. The cells or meshes in the outer organ, formed by its reticulated fibres, are rhombic in shape, and very minute, so as to require a lens to see them well. The component tissue of the inner organ is some- what flaky, and also cellular. The nerves of the outer organ are branches of the fifth pair, which runs beneath the lateral line and above the aponeurotic covering of the organ. This aponeurosis is pierced by many holes for the transmission of the nerves, which are lost within the cellular tissue of the organ. The intercostals supply the inner organ : their electrical branches are numerous and remarka- bly fine.f The organs of the other known electrical fishes have not yet come under the notice of any anatomist. In taking a general view of these interesting organs, we are struck with the existence of a certain degree of analogy amongst them, and yet we fail to discover such resemblances as might be expected, and such as exist between the structures of other organs performing the same functions in different animals. Here we have tendinous membranes variously arranged, yet all so as to form a series of separate cells filled with a gelatinous matter. But how great is the difference between the large columnar cell in the torpedo full of delicate partitions, and the minute rhombic cells of the Silurus ! All, however, are equally supplied with nerves of very great size, larger than any others in the same animals; and, indeed, we may venture to say, larger than any nerve in any other ani- mal of like bulk. " Abhandl. der Acad. v. Berlin, 1820-21. 229, and Blainville, Princ. d'Anat. Comp. i. 232. t Rudolphi, (Abhandl. der Acad. v. Berlin. 1824.) 140. The organs vary in different fishes ; first, in situation relatively to other organs. They bound the sides of the head in the torpedo ; run along the tail of the Gymnotus, and sur- round the body of the Silurus ; secondly, in having different sources of nervous energy ; and, thirdly, in the form of the cells. No other fishes have aponeuroses so extensive, or such an accumulation of gelatine and albumen in any cellular organ. Broussonet remarked that " all the electrical fishes at present known to us, although all belonging to different classes, have yet certain characters in common. All, for instance, have the skin smooth, without scales, thick, and pierced with small holes, most numerous about the head, and which pour out a peculiar fluid. Their fins are formed of soft and flexible rays, united by means of dense membranes. Neither the Gymnotus nor torpedo has any dorsal fin ; the Silurus has only a small one, without rays, situated near the tail. All have small eyes."* X. Analogies of animal electricity . — Setting aside the vague hypotheses of the older philo- sophers, (some of whom attributed the phe- nomena produced by the peculiar power of electrical fishes entirely to the mechanical effect of certain rapid motions of their surface, and others to the influence of currents of minute corpuscules flowing from the body of the fish in the act of discharging,) we can have no dif- ficulty in referring this very remarkable series of phenomena to the agency of some power very analogous to common or voltaic elec- tricity, which seems to stand in the same rela- tion to these as they do to electricity derived from other sources.-f- It was by Muschenbroek that the effects of the torpedo's discharge were first referred to electricity. He was led to imagine that the agent producing the shock was truly electrical from the similarity of its effects to those of the discharge of the Leydenjar. Succeeding observations, however, as we have seen, have shewn that certain differences exist between the phenomena produced by Animal Electricity and those observed in con- nexion with the discharge of the Leyden jar : the chief of these are — its passage through air only to a very small distance; its producing only very slight igniting effects even when con- siderably accumulated ; and its manifesting but feebly the phenomena of attraction and repulsion. Further, it affects the multiplier more strongly than common electricity does under ordinary circumstances, and its chemical effects are more distinct. From voltaic elec- tricity it is distinguished by the comparative feebleness of its power of decomposing water; by the greater sharpness of the shock caused by the discharge, and by the weakness of its magnetizing power. Only four of the eight experimental effects enumerated by Dr. Faradayf as characteristic * Mem. de l'Acad. de Paris, 1782. 693. t It is interesting to know that the Arabic name of the torpedo (Rausch) means also lightning. X Philos. Trans. 1833. 94 ANIMAL ELECTRICITY. of common and voltaic electricity are pro- duced by animal electricity; which appears to be sufficient to prove that the latter is as much a peculiar power distinct from these as are the agents called magneto-electricity and thermo-electricity. Perhaps, however, what we at present regard as so many powers dif- fering from one another in their natures, may be merely modifications of the same power, varied in its sensible properties by changes in the circumstances under which they are mani- fested. This latter view is that taken by D.r. Wilson Philip, who holds that Animal Elec- tricity is just common electricity modified in its properties by those of life, under the in- fluence of which it operates in the living animal. Sir Humphry Davy thought he saw a stronger analogy between common and animal electricity, than between voltaic and animal electricity, but concluded that the latter would be found by more extended researches than he was able to make to be " of a distinctive and peculiar kind."* Cavendish, on the other hand, believed that there is a complete identity between common electricity and that of fishes. And this lie laboured to prove by imitating several of the peculiarities of the discharge of the torpedo by a particular arrangement of small Leyden jars, forming a battery, from which the electricity was discharged in large quantity but of low intensity.f Others, again, have attempted to trace a certain resemblance between the structure of the electrical organs of the torpedo and the formation of the voltaic pile, " inasmuch as they are formed of alter- nate layers of moistened conductors of dif- ferent natures, to wit, of membranous parti- tions, and of gelatinous and albuminous fluid." (Tiedemann.) They suppose that the nerves, being spread over one side of the transverse partitions of the cells, produce opposite states of electrical tension on the two sides of the partition. In the present imperfect state of electrical science, all such hypotheses are un- satisfactory. The only conclusions which, in our opinion, can be legitimately drawn from the accumu- lated facts on the subject are — that the shock given by electrical fishes is caused by an agent closely allied in its nature to common elec- tricity and other like powers ;} and that the developement and discharge of this agent are strictly dependent on the integrity of the ner- vous communication between certain peculiar organs and the great nervous centres. It is evident that the nervous system plays a very important part in the electrical function. But whether its influence merely stimulates the electrical organs to do what their organic * Philos. Trans. 1829. 16. t Philos. Trans. 1776. 196. % The latest experiments on the subject, with which we are acquainted, are those of Messrs. Becquerel and Breschet, reported to the Academy of Sciences in October, 1835, (Ann. des Sciences Nat. n. s. iv. 253,) which seem to have been per- formed with great care. The experimenters com- pletely satisfied themselves that the shock of the torpedo is the result of an electrical discharge . ■ structure renders them capable of doing, or really supplies them with a stream of the im-, ponderable agent which they accumulate, and then, under voluntary impulses, discharge,, is still a point for further investigation. In the structure of the electrical organs, we do not see any arrangement such as researches in elec- tricity artificially developed lead us to believe fitted either to produce or to accumulate elec- tricity. But this is in itself no reason why we should conclude that the organs have not such powers. It seems more in accordance with what we know of the actions of other parts of the animal frame, to believe that they do possess such powers. But — if the elec- trical organs, by their organic structure, be fitted to develope and to discharge electricity under the nervous influence, just as a gland secretes its peculiar fluid and its ducts eject it, why (it may be asked) are the nerves going to these organs of so very great a size compared with the same parts in other organs of similar bulk and very energetic action ? Is their sub- jection to the will of the animal sufficient to account for the difference ? or does it indicate, as some physiologists maintain, that the ner- vous influence does more in this case than merely supply the vital stimulus such as is received by all other organs in common ? In other words — is the agent discharged by the fish as electricity first developed in the ner- vous centres, and only accumulated in the electrical organs ; and is this agent identical with common nervism ? To these questions we cannot yet give a satisfactory reply. They point the way to some very interesting and im- portant fields of investigation, and cheer us with the hope of considerably extending our acquaintance with the physiology of the nerves, on the supposition that the phenomena of ani- mal electricity shall one day be proved to be owing to an accumulation and discharge of the very same agent that causes contraction of muscles, &c. Such a view appears to have been taken of this subject by Sir II. Davy when he remarked,* " there seems a gleam of light worth pursuing in the peculiarities of animal electricity, — its connexion with so large a nervous system, — its dependence on the will of the animal, — and the instantaneous nature of its transfer, which may lead, when pursued by adequate inquirers, to results very important for physiology." Treviranus, in 1818, suggested the likelihood of the power concerned m the ma- nifestation of electrical phenomena by animals, being one of those on which continuance of life in general depends. " Perhaps," said he,f " it is the same power which enables the tor- pedo to give electric shocks that is the imme- diate cause of the contraction of muscular fibres." The same hypothesis is thus ex- pressed by Carus4 " Numerous nerves are distributed upon the cells of the electrical organs, and as it is through the agency of * Philos. Trans. 1828. t Biologie. v. 141. \ Traite element, d'anat. comp. 2d edit. i. 392. (French translation by Jourdan. ) ANIMAL ELECTRICITY. 95 these nerves that the organs act, it is not im- possible that the nervous influence itself is accumulated in these cells as in condensers, and that it is discharged at will, just as this influence is accumulated in the muscular tissue to produce contraction of its fibres." It was reflection on the phenomena of animal elec- tricity that led Dr. Wollaston to form the hy- pothesis, which he supported with so much ability, of secretion in general being depen- dant on electricity, conveyed by the nerves, and acting on the secerning organs.* Dr. Wilson Philip, also, thinks that the circum- stances under which electrical action is mani- fested by fishes go to the support of his theory of the nervous influence being identical with common and voltaic electricity. Dr. Faraday says that, from the time that it was shewn that electricity could perform the functions of the nervous influence, he has had no doubt of their very close relation, and probably as effects of one common cause. To the numerous list of learned observers who have speculated on this interesting subject, we have to add the re- spected name of Sir John Herschel, who imagines that the present state of electrical science warrants the conjecture, that the brain and spinal marrow form an electric organ, which is spontaneously discharged along the nerves, at brief intervals, " when the tension of the electricity reaches a certain point. "f Meissner, again, supposes that the blood be- comes charged with electricity in the lungs, during the chemical process of respiration ; that the electricity immediately traverses the nerves of the lungs, and then the other parts of the ganglionic system ; that hence the cen- tral organs of the nervous system become charged ; and that the brain, on and through which the will acts, being charged, excites the several organs to activity through the medium of their respective nerves, along which electric currents are passed.} The facts, (in addition to those which have chiefly engaged our atten- tion in this article,) upon which such theories are built are, — (1) that the muscles of an animal recently dead contract when common electricity passes through them, just as they do when they are subject to the animal's will ; (2) that voltaic electricity acts upon secreting organs, so as to enable them in some degree to carry on their functions after their proper nerves have been cut; and (3) that the same agent appears to influence powerfully the capillary circulation. But, although these facts, taken along with what we know of the phenomena of the electricity of fishes, certainly do appear to favour the views to which we have just ■* Phil. Mag. xxxiii. 488. f Discourse on the Study of Nat. Phil. 343. t Syst. der Heilkunde. Wien. 1832. If hypo- theses such as these should hereafter be proved to express the true state of the case, the electrical fishes will become objects of great interest to the physiologist, as presenting him with opportunities, such as no other animals afford, of studying in accumulation the properties of that wonderful agent, which is the moving power of the animal organiza- tion, and a very important link in the chain of causes and effects bj< which life is manifested. alluded, there are yet other facts which are so' hostile to them as to make it probable that they do not express the truth. For instance, the most carefully conducted experiments have failed to demonstrate the existence of electric currents through muscles during their contrac- tion; which, from all that is known of the phenomena exhibited by electricity in other circumstances, it may be presumed would not have been the case had it been the immediate stimulant of muscular contraction. M. Per- son has applied the poles of a galvanometer to the spinal marrow without obtaining any indi- cations of the existence of electrical currents through its substance. The subjects of Per- son's experiments were cats, dogs, rabbits, eels, and frogs. The spinal canal having been opened, the piles of the galvanometer were placed in communication with the anterior and posterior columns of the cord. This was clone at different parts, after the roots of the nerves had been cut. Small plates of platina, with which the wires of the instrument were armed, were thrust into the cerebellum and into several of the largest nerves. These experiments were repeated after the animals had been placed under the influence of strychnia. But there was no certain indication of electricity ob- tained, although the most delicate instruments were used.* Person's experiments have been repeated by Muller with the same results. Messrs. Prevost and Dumas, however, state that, having armed the branches of their gal- vanometer with two wires of platina, exactly alike, and having plunged one of them into the muscles of a frog's leg, while, with the other, heated to redness, they touched its nerves, they saw considerable deviations of the needle of the instrument follow the contrac- tions of the muscles.f But seeing that the electricity made manifest in this experiment may have been developed rather by the con- tact of the hot wire and the nerves than by the nervous actions, we cannot admit that it is sufficient to prove the existence of electrical currents in muscles during their contraction. Dr. Faraday, also, has lately experimented on living muscles with the very delicate galvano- meter invented by himself, but has entirely failed to obtain indications of moving electri- city. Negative results such as these, obtained by so many practised observers, are sufficient to induce us to withhold our assent from those theories which make nervism identical with electricity, until the whole subject shall have been more fully investigated. As in some degree illustrative of the pheno- mena of animal electricity, properly so called, we must here take notice of the manifestation of common electricity in animal substances and in living animals. The mere contact of heterogeneous bodies is * Journal de Physiol, x, 217. Some years ago M. Pouillet announced that he had witnessed electrical phenomena during the operation of the acupuncture of muscles ; but he has since con- fessed that he was deceived. f Edwards, De l'iiifiuencc ties agens physiques sur la Vie, in Appendix. 96 ANIMAL ELECTRICITY. sufficient for the development of electricity; and animal tissues of dissimilar natures, both living and dead, obey the same law as other sub- stances in this respect. For instance, a kind of voltaic pile has been formed by building up layers of muscle and nerve placed one above the other alternately; (Buntzen :) also by placing one upon another alternate layers of muscular fibre and brain, separated by a porous substance, soaked in salt-water. (Lagrave.) Another such has been made with plates of one kind of metal, fresh muscle, and salt-water, or blood, which acted on the galvanometer. When the con- ductors of a galvanometer (Schweigger's) are armed with plates of platina, on one of which a piece of muscle of a few ounces in weight is placed, and the conductors are then plunged in blood or in a weak solution of salt, a deviation of the magnetic needle of the in- strument is perceptible. (Prevost and Dumas.) The same happens when to one conductor is applied a plate of platina moistened with mu- riate of antimony or nitric acid, to the other a piece of nerve, muscle, or brain, and both are brought into contact. (Majendie.) Dry piles of considerable electrical power may be formed of organic materials alone, without the interven- tion of metals. If concentrated extracts of organic bodies (animal or vegetable) be spread upon thin paper, and piles be built up of discs cut from this paper, so that two dissimilar layers be separated by two thicknesses of the paper, so much electricity is developed that the elec- trometer is affected. (Kcemtz.) When two persons, both insulated, join hands, electricity is developed sufficiently to affect Coulomb's electroscope. And, if the contraction of mus- cles, the nervous connexion of which with the living body has been destroyed, be considered as a proof that thpy are subject to the influence of electricity, there are numerous experiments on record tending to prove that electricity is evolved by the mere contact of two dissimilar animal substances. Galvani, Volta, Humboldt, Aldini, Kellie, and Miiller, have all found that when the muscles and the great nerves of a frog's limb are touched synchronously with a piece of the muscle of a warm-blooded animal, weak contractions of the frog's muscles ensue ; and that, when the crural muscles are cut and folded back so as to touch the lumbar nerves, muscular contractions are perceived in the lower part of the limb. Aldini excited most powerful contractions by bringing the nerves of a warm- blooded animal into contact with the muscles of a cold-blooded animal, and vice versa. And Miiller has further found that contractions are excited by touching the moistened skin of the leg with the nerves of the thigh dissected out and turned down upon them ; the nerves being- held by means of an insulating rod.* Tiedemann thus states the general results of experiments such as these. "1. The nerves of the muscles in which it is proposed to excite convulsions must make part of the chain. 2. The nerve or portion of nerve which is to * Handbuch der Physiol, des Mensclicn. Berlin, 1833. make part of the chain must be isolated as completely as may be, and no other conductor must produce derivation in this portion of the chain, so as to oblige the electric current, when developed in the chain, to take a course through the nerves. 3. Cceteris paribus, the convulsions are so much stronger, and are manifested over a greater extent, as the nervous portion, acting as a conductor, enters into the chain. 4- The convulsions are so much more powerful, and last the longer, as the chain is quickly formed, and the surface with which the parts consti- tuting it are in contact is extensive."* And lastly, we now know that even the evaporation of fluids, and changes in the molecular consti- tution of both solids and fluids are always accompanied by electrical excitation. . Applying these facts to our knowledge of the various processes of the animal ceconomy, we cannot but conclude that, in the course of the many interchanges that are constantly taking place amongst the component particles of all living organs, electricity (perhaps modified by the organic forces) must be developed alto- gether independently of nervous influence. It is certain, however, that electricity flowing from this source is very feebly manifested ; at least it affects our best electrometers in a very incon- siderable degree. Saussure frequently ex- amined the electricity of his own body by means of Volta's electrometer, used along with a condenser, but always failed to perceive any indications of free electricity while he was entirely naked. It was also imperceptible while lie perspired freely, and when his clothing was cold. Under other circumstances, he found the electricity of his body sometimes positive, and at other times negative ; but he could not determine the causes of these variations. Simi- lar observations were made by Hemmer of Mannheim in 1786, both on the electricity of his own body, and on that of many other indi- viduals placed in various circumstances. He obtained the following results. 1. Electricity is developed in all men, but varies in intensity and in nature in different individuals. 2. The character and intensity of the electricity fre- quently varies in the same person. In 2422 experiments, it was 1252 times positive, 771 negative, and 399 times imperceptible. 3. When the body is at rest and warm, its electricity is always positive. 4. When the surface is much cooled, the electricity becomes negative. 5. It is also negative when the muscular vigour is diminished. More recently this subject has been investigated by Messrs. Pfaff and Ahrens.f They used a gold-leaf electrometer; and the subjects of their observations were insulated. The collecting plate screwed on the electrometer was touched by the person experimented upon. The upper plate of the same was placed in communication with the ground by means of conductors. The results which they thus pro- cured were as follows: — 1. The electricity of healthy men is generally positive. 2. Irritable men of sanguine temperament have more free * Pliysiol. trans!, by Drs. Gully and Lane, 276". t Meckel's Arehiv. iii. 161. ANIMAL ELECTRICITY. 97 electricity than those of a phlegmatic tempera- ment. 3. An increased accumulation of elec- tricity takes place in the evening. 4. Spirituous drinks augment its intensity. 5. The elec- tricity of Women is more frequently negative than that of men. 6. In winter, while the body is very cold, no electricity is manifested, but it gradually reappears as the body is warmed. 7. The whole body naked, as well as every part of .it, shews the same phenomena. 8. During the existence of rheumatism, the electricity is greatly diminished in intensity, but as the dis- ease declines it again increases. Gardini found that the electricity of women during menstrua- tion and pregnancy is negative. Some individuals exhibit electrical pheno- mena much more readily than others. Some persons, for instance, hardly ever pull off articles of dress worn next the skin without sparks and a crackling noise being produced. It is related of a certain monk that sparks were always emitted from his hair when it was stroked back- wards ; and of an Italian lady that her skin, when rubbed with a linen cloth, gave out sparks, attended with a crackling noise. The same phenomenon, as exhibited by the cat, and by other animals covered with a soft fur, is daily observed. But it has been stated that the cat's electricity may be accumulated in its own body and given off suddenly, so as to produce a shock. Romer says,* " If one take a cat in his lap, in dry weather, and apply the left hand to its breast, while with the right he strokes its back, at first he obtains only a few sparks from the hair; but, after continuing to stroke for some time, he receives a sharp shock, which is often felt above the wrists of both arms. At the same moment, the animal runs off with expressions of terror, and will seldom submit itself to a second experiment." In repeating this experiment, we have obtained the like result. We are not aware of any other observer having met with any thing resembling an accumulation of electricity in quadrupeds, excepting Cotugno, who asserted that, in dissecting a living mouse, lie felt an electric shock when its tail touched his finger.f XL Uses of animal electricity. — The pur- pose which the electrical function is fitted to serve in the animal economy is proba- bly not single. It is very evident that the discharge from the organs frequently strikes terror into the enemies of their possessors, and thus it may be regarded as a means of defence; while, in certain circumstances, it may be useful in enabling the fish more easily to secure its prey. But this, probably, is not all. It is very likely, as Dr. Roget has suggested,! that the electrical organs communicate to the fish perceptions of electrical states and changes in surrounding bodies, (very different from any that we can feel,) in the same way as other organs of sense convey perceptions with regard * Gilbert's Ann. der Phys. B. xvii. t Humboldt. Ueber die gereii-te Musk-ei-uttd- ' Nervenfaser. Berlin, 1793. i. 30. t Bridgewater Treatise, i, 31. , \ L VOL. II. J' V v ,. - — to light and sound. Such perceptions we carl conceive to be very useful and pleasurable to animals living in the dark abysses of the waters. Some of Dr. John Davy's observations make it very doubtful whether the electrical function is ever subservient to that of prehension of food. He kept young torpedos for a period of five months or more, in large jars of salt water, during which time they ate nothing, although very small fishes, both dead and alive, were put into the water. Yet they grew, and their elec- trical energies and general activity increased.* The small fishes seemed to have no dread of the torpedos. On one occasion, however, when a lively torpedo was placed in a small vessel along with a smelt, and excited to discharge, the smelt was evidently alarmed, and once or twice, when exposed to the shock, leaped nearly out of the vessel, but it was not injured by the electricity. It has also been frequently ob- served of the gymnotus that it eats very few of the fishes that it kills by its discharge. The electrical power of the young fish is proportionally very much greater than that of the old, and can be exerted without exhaus- tion and loss of life much more frequently. After a few shocks, most of the old fish which Dr. Davy has endeavoured to keep alive have become languid, and died in a few hours, whilst young ones, from three to six inches long, remained active during ten or fifteen days, and sometimes lived as many weeks. Hence Dr. Davy concludes that the chief use of the electrical function is to guard the fish from its enemies, rather than to enable it to destroy its prey, and so provide itself with food. He fur- ther conjectures that, besides its defensive use, the electrical function may serve also to assist in respiration by effecting the decomposition of the surrounding water, and so supplying the gills with air when the fish is lying covered with mud or sand, in which it is easy to con- ceive that pure air may be deficient. And Dr. Davy has often imagined that he saw something of this kind going on. After repeated dis- charges, he has observed, all around the margin of the pectoral fins, an appearance as if very minute bubbles of air were generated in it and confined. That this may be one purpose which the electrical function is designed to serve, is rendered still more probable by the circumstance, that the gills (in the torpedo at least) are largely supplied with twigs of the electrical nerves. In fishes in which he had cut the electrical nerves, Dr. Davy found the secretion of the cutaneous mucus considerably diminished or altogether arrested ; and hence he supposes that the electricity assists in the production of this fluid. Lastly, it has been conjectured that the elec- trical function is subservient to that of digestion. This idea was started by Mr. J. Couch some years ago.f He says, " Without denying that the torpedo may devour that which it disables by the shock, I conceive that the principal use of this power has a reference to the functions of -J Phil. Trans. 1835. >"> s j N^Jiinn. Trans, xiv. 89. «-'. { ' A"*** H / 1 98 NDOSMOSIS. digestion. It is well known that an effect of lightning or the electric shock is to deprive animated bodies very suddenly of their irrita- bility ; and that thereby they are rendered more readily disposed to pass into a state of disso- lution than they would otherwise be; in which condition the digestive powers of the stomach can be much more speedily and effectually exerted on them. If any creature may seem to require such a preparation of the food more than another, it is the torpedo, the whole intes- tinal canal of which is not more than half as long as the stomach." These views receive some support from the fact that the nerves of the stomach are derived from those supplying the electrical organs ; and perhaps also from the fact, reported by Dr. Davy regarding a torpedo, in which, after it had been frequently excited to give shocks, diges- tion seemed to be completely arrested. The only conclusion to which, in the present state of our knowledge, we can come on this point is, that although the electrical organs form a very efficient means of defence from their enemies for the fishes which possess them, this is not the only purpose they are intended to serve ; what, however, their other uses are is at present only matter of conjecture. There remains yet unentered upon a large field of enquiry connected with the physiology of those wonderful organs, which, we doubt not, will yield to future ages very striking examples of that nice and close adaptation of means to ends which so clearly proves to us the existence and continued exercise of Wisdom Supreme, " upholding all things by the word of his power," making the smallest of his works " very good," and " to be thought upon." Bibliography.— Volta, Memorie sull' elettri- cita animali, 1782. Gahani, Dell' uso e dell' at- tivita dell' arco conduttore nelle contrazioni dei moscoli. Bologna, 1794. Ejus. Memorie sull' elettricita animate, Bologn. 1797. Fowler, Expe- riments and Observations relative to the influence called animal electricity. Lond. 1793. Aldini, Essai Theorique et experimental sur le Galvanisme, et in Bulletin des sciences, an xi.. No. 68. Pfaff, Ueber thierische Elettricitiit und Reizburkeit. Leipzig, 1795. Humboldt, Versuche iiber die ge- reizte Muskel und Nervenfaser. Berlin, 1797. Treviranus, Biologie. Tiedemann, Physiologic M'uller, Physiologie. Carus, Anat. Comp. French ed. t. i. Lorenzini, Osservazioni interno alle tor- pedini, Flor. 1678. Walsh, Phil. Trans. 1774. Pringle on the Torpedo, Lond. 1783. higenhousz, Phil. Trans. 1775. Hunter, Phil. Trans, t. lxiii. et lxv. Geoffrey Saint Hilaire, Ann. du Mns. t. i. Humboldt, Kecueil d'observ. de zoologie et d'anat. comp. Knox, Edin. Journal of Science, 1824. Todd, Phil. Trans. 1816. Davy, Phil. Trans. 1834. Majendie and Desmoulins, Anat. des Systemes Nerv. t. ii. Rudolphi, Abhandl. der Acad, der Wissen- schaft in Berlin, 1820. Becquerel, Tiaite d'Elec- tricite et Galvanism, t. iv. Par. 1836. (John Coldstream. ) ENCEPHALON. In order to lay before the reader a connected view of the Anatomy of the Encephalon in conjunction with that of the Medulla Spinalis, the Anatomy of both these organs will be given under the article " Ner- vous Centres." ENDOSMOSIS, (ivSov, intus, acr^o?, im- pulsus). — Accident having made me acquainted with the fact that a small animal bladder, con- taining an organic fluid, became considerably distended by remaining for some time plunged in water, and that the water even expelled" the thicker fluid contained within the bladder, when there was a hole by which it could escape, I be- thought me of the probable cause of this pheno- menon, and soon came to the conclusion that it depended on the difference of density between the included or interior fluid, and the water or exterior fluid. I found that the coeca of fowls filled with milk, thin syrup, &c. and secured with a ligature, became turgid and even excessively distended when treated in the same way. I now discovered that the fluids contained in the coeca permeated their coals, and were diffused in the surrounding water. I saw, further, that two opposite currents were established through the parietes of the coeca; the first and stronger formed by the exterior water flowing towards the fluid contained in the coeca; the second and weaker, by the thick included fluid flow- ing towards the water. To the first of these currents I gave the name of Endosmosis, and to the second that of Exosnwsis. These titles, I must allow, are objectionable, and perhaps badly chosen. The first conveys the idea of an entrance and the second of an exit. Now, the phenomenon, regarded in its proper point of view, consists in a double permeation of fluids, abstracted from any idea of entrance or exit. Besides, the current of endosmosis, which, etymologically speaking, expresses an in-going current, may nevertheless be, experimentally speaking, an out-going current ; this, for exam- ple, happens when a hollow membranous organ, containing water, comes to be placed in contact exteriorly with a fluid more dense than water. There is then a current of endosmosis which goes out of the bladder, and a current of exos- mosis which enters it. Thus facts are found in contradiction to the terms, and these I should not have hesitated to change, if their general adoption did not render this change very diffi- cult, and subject to great inconvenience. I have, therefore, resolved to retain them, wishing it to be understood by naturalists that no attention is here paid to their etymological signification. To estimate the amount of endosmosis I contrived an apparatus to which I gave the name of endosmometer ; it consists of a small bottle, the bottom of which is taken out, and replaced by a piece of bladder. Into this bottle I pour some dense fluid, and close the neck with a cork, through which a glass tube, fixed upon a graduated scale, is passed. I then plunge the bottle, which I entitle the reservoir of' the endosmometer, into pure water, which, by en- dosmosis, penetrates the bottle in various quan- tities through the membrane closing its bottom. The dense fluid in the bottle, increased in quan- tity by this addition, rises in the tube fitted to its neck, and the velocity of its ascent becomes the measure of the velocity of the endosmosis. To measure the strength of endosmosis, I have made use of an endosmometer in which the tube was twice bent upon itself, the as- ENDOSMOSIS. 99 tending branch containing a column of mer- cury,* which was raised by the interior fluid of the §ndosmometer in proportion as the en- dosmosis, increased the volume of this fluid.* By means of these two instruments I have foetid that the velocity and strength of endos- mosis follow exactly the same law. Both are m relation to the quantities which express, in two comparative experiments, the excess of density of two dense fluids contained in the endosmometer, above the density of water, which in these two experiments is exterior to the instrument. Thus, for example, in putting successively into the same endosmometer, syrup of which the density is 1.1, and syrup of which the density is 1.2, and in plunging in both cases the reservoir of the endosmometer into pure water, you obtain in the first case an en- dosmosis, of which the strength and velocity are represented by 1 , and in the second case an endosmosis, of which the strength and velocity are represented by 2 ; that is to say, by the numbers relative to the fractionals 0.1 and 0.2, which express the excesses of density of the two solutions of sugar above the density of water, which is 1. I have ascertained by ex- periment that the strength of endosmosis is such that, with syrup of which the density is 1.11, and an endosmometer, the opening of which is closed by three pieces of bladder, one over the other, you obtain an endosmosis which raises the mercury to 1 metre 238 millimetres, or 4.5 inches 9 lines, which is equivalent to an elevation of water of 16 metres 77 centimetres, or 51 feet 8 inches. It follows from this, that in employing syrup, of which the density was 1.33, (its ordinary density,) you would obtain an endosmosis, the strength of which would be capable of raising water more than 150 feet. Fluids of a different nature have, with refer- ence to endosmosis, properties which are in no way in proportion to their respective densities. Thus sugar-water and gum-water of the same density, being put successively into the same endosmometer, which is plunged into pure water, the former produces the endosmosis with a velocity as 17, and the latter with a velocity as 8 only. I have seen, in the same manner, a solution of hydrochlorate of soda and a solution of sulphate of soda of the same density, put successively in the same endosmo- meter surrounded with pure water; the velo- city of the endosmosis produced by the solu- tion of sulphate of soda is exactly double that of the endosmosis produced by the solution of hydrochlorate of soda. These results are inva- riable, and I am persuaded that if 1 have ever obtained a different result, the experiment has been defective. I have made several experiments since with gelatinous and albuminous waters placed suc- cessively in the same endosmometer, surround- ed with pure water, which produced endos- mosis severally in the proportion of 1 to 4 ; so that the albumen had four times more power of endosmosis than the gelatine. I have seen * See my work entitled, Nouvelles Recherches sur l'cndosmose et l'exosmose, &c. 8vo. Paris, 1828. by another experiment that the power of en- dosmosis of syrup is to the power of endos- mosis of albuminous water of the same den- sity, as 11 is to 12. All alkalies and soluble salts produce en- dosmosis ; so do all acids, but each with spe- cial phenomena, which will be noticed by and by. These chemical agents in general occasion an endosmosis of short duration only, when the endosmometer is closed with a portion of an animal membrane. Organic fluids alone, which are not very sensibly either acid or alkaline, or salt, produce lasting endosmosis, which, in- deed, does not stop until the fluids are altered by putrefaction, when they become charged with sulphuretted hydrogen. I have shown that when an endosmometer is closed with a thin plate of baked clay instead of the animal mem- brane, the endosmosis which a saline solution produces, and which would have stopped in a few hours with the animal membrane, continues to go on indefinitely with the baked clay. The property of destroying endosmosis may be considered as belonging to all chemical re- agents, but merely on account of their sus- ceptibility to enter into combination with the permeable partition of the endosmometer. Thus all acids, alkalies, soluble salts, alcohol, &c. being disposed to combine with the elements of organic membranes, destroy endosmosis, al- though they had induced it before their complete combination with the elements of the membrane had taken place ; and it is not until this combi- nation is complete that endosmosis ceases. Or- ganic fluids, which have no chemical action upon the elements of the membrane of the endosmo- meter, ought not, consequently, to tend to the destruction of endosmosis, unless some change should take place which should give them a chemical action, such as they usually acquire by decomposition, when they usually become charged with sulphuretted hydrogen. My earlier experiments tended to show that carbonate of lime (chuux carbonatee ) reduced to thin laminje, and employed to close an en- dosmometer, is totally without the power of producing endosmosis ; my latter experiments have somewhat modified this conclusion. After having vainly employed lamhrae of carbonate of lime of greater or less thickness, I finished .by making use of one of white marble, two millimetres in thickness, but with no better success. Without carrying my experiments further, I concluded that porous carbonate of lime was totally unapt to excite endosmosis. This conclusion having, notwithstanding, left some doubts in my mind, I again took the same plate of marble with the intention of measuring- its permeability to water, compared with the various degrees of thickness which I could give it, and of renewing, at the same time, my at- tempts to make it produce endosmosis. Having closed an endosmometer with this plate of mar- ble, I filled the reservoir and the tube of the instrument with pure water, and suspended it over a vessel filled with water, in which the plate of marble only was immersed. If the marble had been permeable to water, the fluid con- tained in the endosmometer would have flowed h 2 100 ENDOSMOSIS. through the capillary conduits of the plate, and this flow would have become perceptible by the sinking of the water in the tube, the inte- rior of which was only two millimeters in dia- meter. The result of this experiment was that the plate of marble, which was four centimeters in diameter, did not lose by filtration, in one day, more than the small quantity of water capable, by its subtraction, of lowering its level one millimeter and a half in the tube. I next tried syrup in this endosmometer, the reservoir being plunged into pure water ; but no endosmosis was induced. I now reduced the thickness of the plate of marble to one millimeter and a half; in this state it lost by filtration, in the course of a day, eleven mil- limeters of water measured by the tube. The permeability of this plate was, as may be per- ceived, very sensibly increased : still the en- dosmometer which it closed when filled with syrup showed no indications of endosmosis. 1 reduced the thickness of the plate of marble to one millimeter. In this state it lost by fil- tration, in the space of a day, twenty-one milli- meters of water measured in the tube. I put into the endosmometer, which this plate of marble closed, the same syrup which had been used in the preceding experiments, and the density of which was 1.12, and I now ob- tained an endosmosis which manifested itself by an ascension of seven millimeters in four- and-twenty hours. This last experiment proved ' to me that carbonate of lime was not, as I had hitherto found it, totally without the power to produce endosmosis. 1 wished to compare this plate of marble with a piece of bladder of the same surface under the double point of view, of their permeability, and their respec- tive properties of producing endosmosis. Having therefore taken off the plate of marble which closed the endosmometer, I replaced it by a piece of bladder whose permeability to water I measured in the same manner as above. 1 found this permeability very nearly equal to that of the plate of marble of one millimeter in thick- ness. I then put into this endosmometer some syrup similar in density to that which I had used in the same endosmometer closed with the plate of marble. The endosmosis which I obtained raised the syrup seventy-three millimeters in three hours. Thus the permea- bility to water being equal in the bladder and in the plate of marble, the endosmosis pro- duced by the first was to the endosmosis pro- duced by the second as 584 is to 7, a most extraordinary difference, and difficult to be accounted for. These experiments prove that carbonate of lime is but very little apt to pro- duce endosmosis, in which it differs singularly from baked clay, thin laminaB of which are almost as apt to produce endosmosis as organic membranes. The varieties of sulphate of lime which may be employed in endosmometrical experiments are not sufficiently numerous or of sufficient variety of permeability for it to be possible to appreciate the properties of this substance in relation to endosmosis. I found that the sul- phate of lime used in the manufacture of plaster in the environs of Paris, employed in thin plates to close an endosmometer, did not produce endosmosis. But this mineral is per- haps too easily permeable. In fact it is found impossible to obtain endosmosis when the in- terior fluid of the endosmometer flows easily by filtration, in virtue of its weight, through porous plates. I should say as much of plates of freestone ( gres) which I have employed without success in these experiments, but that I recollect to have obtained the phenomenon in a very slight degree with a plate of freestone very close-grained and very little permeable to fluids. I have tried a variety of experiments shew- ing that an increase of temperature increases endosmosis. This result has been confirmed by repeated experiments. The quantity of the same fluid introduced by endosmosis, and with the same sort of per- meable partition, is generally in proportion to the extent of surface of this partition. The following experiment demonstrated this fact. I took two endosmometers, the membranes of which, taken from the same bladder, were of diameters in the relation of one to two; I filled the reservoirs of these two endosmometers with syrup of equal density, and then plunged them into pure water. I had taken care to weigh them previously with great exactness. After continuing the experiment for two hours, I weighed the instruments afresh, and found in the large endosmometer four times as great an increase of weight as in the small one, which proved that the first had introduced, by endos- mosis, four times as much water as the second. This relation was exactly that of the extent of surface of their respective membranes, the diameters of which were as one is to two, and their surfaces consequently as one is to four. 1 have thus enumerated the effects; let us now endeavour to ascertain their causes. The first idea which presented itself to my mind to explain the phenomenon of endosmosis was that it was owing to electricity. We know that effects exactly similar to those of endos- mosis are produced by means of the electricity of the voltaic pile in the experiment of M. Porret, inserted in the Annates de Chirnie, vol. xi. p. 137. This naturalist having divided a vessel into two compartments by a septum of bladder, filled one of the compartments with water, and put only a small quantity in the other. Havmg placed the positive pole of the pile in communication with the compartment full of water, and the negative pole with the compartment containing little water, the fluid was forced through the bladder from the full compartment into the almost empty one, and there rose to a higher level than that to which it was reduced in the original full compart- ment. I varied this experiment by applying it to my own apparatus. I put pure water into an endosmometer, the membrane of which was plunged into water. I made the interior water of the endosmometer communicate with the negative pole of the pile, and the exterior END0SM0S1S. 101 water with the positive pole. I soon saw the water rise in the tube of the instrument : en- dosmosis had taken place. The similarity of effects led me to admit that some particular and unknown mode or form of electricity was the cause of the endosmosis produced by the heterogeneous nature of fluids. It was in vain, however, that I tried to discover signs of this electricity with the most delicate electro- meters. In reflecting afterwards upon what might be the common cause of the phenomenon pre- sented in Porret's experiment and that of or- dinary endosmosis, I was inclined to think that electricity might not be the immediate cause of the effects exhibited, and that it only acted in the case cited by producing heteroge- neousness of quality in the two fluids subjected to the positive and negative poles. Experience seems to have confirmed my doubts on this point. I took a small endosmometer of glass, closed by a piece of bladder, and filled its re- servoir with water coloured blue with the co- louring matter of violets; I plunged the reser- voir of this endosmometer into the same co- loured water contained in a small glass vessel ; I put this latter fluid in communication with the positive pole of the voltaic pile, and the interior fluid of the endosmometer in commu- nication with the negative pole. The exterior blue fluid soon became red, and consequently acid, and the interior blue fluid became green, and consequently alkaline. These two fluids having thus become heterogeneous, to this may be ascribed the endosmosis which manifested itself, and which increased the volume of the interior fluid at the expense of the volume of the exterior fluid. Thus electricity would not be in this case the immediate cause of endos- mosis, but the remote one ; it would only act in producing the heterogeneous quality in the two fluids, and it would be this quality which would produce the passage of fluids as in the experiments on endosmosis, the discovery of which belongs to me. But let us now inquire in what way hetero- geneousness of quality in two fluids, separated by a membranous partition, occasions the phe- nomenon of endosmosis. Upon this point opinions are greatly divided. M. Poisson and Mr. Power have each, in his own way, given an analytical explanation of the phenomenon, and ascribed it to the action of the capillary canals of the porous septum interposed be- tween»the two fluids. In this explanation the phenomenon of the current of exosmosis is set aside, or regarded as occurring merely acciden- tally. Now this is entirely opposed to the fact, — we have constantly evidence of the simulta- neous existence of the two opposite and une- qual currents of endosmosis and exosmosis. Endosmosis by others has been held to be simply the effect of the viscidity of one of the fluids divided by a porous septum. This visci- dity prevents the upper fluid from permeating the interposed septum, whilst the inferior fluid, little or not at all viscid, filters readily through the septum and mingles with the upper fluid, whose volume it consequently increases. This opinion, published by a man of distinction, de- serves to be seriously investigated. When an equal weight of gum arabic and of sugar is dissolved in two equal weights of water, the viscidity of the different solutions is by no means the same, the solution of the gum is ob- viously more viscid than that of the sugar. Now if these two solutions be divided by a piece of bladder, the current of endosmosis will be found to flow from the solution of the gum towards that of the sugar ; in other words, from the more viscid to the less viscid fluid; in this instance, consequently, we see the more- viscid fluid permeating the membrane with greater facility or in greater quantity, than the1 less viscid fluid. More than this, the same phenomenon takes place if the quantity of the gum be made double that of the sugar. I have, for instance, tried a solution of two parts of gum arabic in thirty-two parts of water, (den- sity 1.023,) and a solution of one part of sugar in the same quantity of the menstruum, (den- sity 1.01-1,) divided by a piece of bladder, and found that the endosmotic current was still directed from the solution of the gum towards that of the sugar. These facts suffice to prove- that the endosmotic current does not always flow from the less towards the more viscid fluid. It is not, therefore, the inequality of vicosity in these two fluids which is, in this instance, the cause of their unequal permeation across the porous lamina which separates them. In order to place these facts beyond a doubt, the comparative viscidity of the gum-water and the sugar-water which were made use of in the experiments of which I have been speaking, required to be accurately measured. Such a comparative estimate of the viscidity of fluids may be obtained by observing the time which an equal quantity of each of them, at the same temperature, takes to run through a glass capil- lary tube. In this way I tried, 1st, pure water; 2d, a solution of one part of sugar in thirty-two parts of water; 3d, a solution of one part of gum-arabic in thirty-two parts of water; 4th, and lastly, a solution of two parts of gum in thirty- two of water. With a temperature of +7° cent. I found that fifteen centilitres of pure water passed through a capillary tube of glass in one hundred and fifty-seven seconds; that fifteen centilitres of the solution of one part of sugar in thirty-two of water passed through the same tube in one hundred and fifty-nine seconds and a half ; that fifteen centilitres of the solution of one part of gum in thirty-two of water passed through in two bundled and sixty-two seconds and one-third ; and that the same quantity of the solution of two parts of gum in thirty-two of water required three hundred and twenty-six seconds to pass through. From these experiments it appears that the viscidity of the solution of sua;ar, in the propor- tion of one to thirty-two of water, (density 1.014,) is very little above that of pure water; that the viscidity of the solution of gum-arabic, in the proportion of one to thirty-two of water, is much greater than that of the sugared water 102 ENDOSMOSIS. just mentioned ; and finally, that the viscidity of the gum-water, containing two parts of gum to thirty-two of water, (density 1.023,) is twice as viscid as the solution of sugar employed. It seems that nothing more is wanting to these proofs of the fact that endosmosis does not depend on the mere viscidity of fluids. Nevertheless I shall cite another proof of this truth. The very singular fact I am about to mention will also prove that the septa employed exert a special influence on the direction in which endosmosis takes place. It is well known that, in separating water from alcohol by an organized animal or vege- table membrane, the endosmotic current flows from the water towards the alcohol. I employed oil-silk (taffetas go?nme ) or silk covered with a layer of caoutchouc, which may be regarded as equivalent to a thin lamina of elastic gum, as the medium of separation between these two fluids. During the first thirty-six hours of the experiment, I observed an extremely slow en^ dosmotic current from the alcohol towards the water. After this period the endosmosis, with the same direction, became very rapid. This increase in the rapidity of the endosmosis I considered due to some alteration in the caout- chouc produced by the action of the alcohol, and in consequence of which it became more readily permeable. The endosmotic current, however, let it be observed, is always from the water towards the alcohol in this experiment, instead of being from the alcohol towards the water, as is constantly the case when the septum between the spirit and the water is formed by an organic, whether animal or vegetable, tissue. We have thus a clear demonstration of the great influence possessed by the septum upon the direction of the current of endosmosis. We have, also, in the instance just quoted, a proof that the different degrees of viscidity of two liquids plays no part in the production of this phenomenon. I would remark that the endos- motic current carrying the alcohol towards the watey athwart the septum of caoutchouc is ac- companied by a counter-current, which carries the water towards the alcohol through the same septum. I assured myself that the alcohol had received some addition of water ; and yet it is well known that caoutchouc is impermeable to water ; which would seem to say that the latter fluid could only have passed through the sep- tum of caoutchouc by becoming mingled with the alcohol occupying the molecular interstices of that substance. Once within these intersti- ces the alcohol attracts the water by the affinity of mixture, (a finite de mixtion ) and enables it to penetrate the substance of the caoutchouc, which denies all access to water when it is pure. It is therefore to the state of commixtion within the capillary tubes of the septum that the two opposed fluids proceed the one towards the other with cross but unequal motions. The means I took to ascertain the fact of water having become mixed with the alcohol was simple enough : I set fire to a quantity of the fluid which had served for the experiment, and found that, after all the spirit had burned out, a considerable quantity of water remained, whilst the alcohol, previously to being so em- ployed, burned away entirely, leaving no water behind it. The theoretical views of Magnus in regard to endosmosis have been adopted by Berzelius in his Chemistry, and the idea upon which they are based has been reproduced by M. Poisson. To give a clear notion of this theory, let us sup- pose that a measure of salt water is separated from a measure of pure water by a permeable septum, a piece of bladder for example ; the current of endosmosis, in this instance, will be from the pure water towards the salt, and for the following reason : in the salt water there are three attractions, namely, the attraction of the molecules of the water for one another; secondly, the attraction of the molecules of the salt for one another; and thirdly, the reciprocal attraction of the molecules of the water and of the molecules of the salt. The pure water on the opposite side of the septum again has no more than a single form of attraction, to wit, that of its particles for one another. The salt water subjected to three attractions will be moved, it may be imagined, with greater diffi- culty than the pure water, the molecules of which are obedient to but one attraction. Con- sequently, in the reciprocal attraction of these two fluids, the one, the molecules of which are the least subjected to attraction among them- selves, will make its way with greatest rapidity athwart the capillary conduits of the dividing membrane. This theory has a seducing aspect, but we shall find immediately that it is inapplicable to certain endosmotic phenomena presented by acids. I have shown above that it is not always to- wards the denser fluid that the endosmotic cur- rent is turned. Thus alcohol and ether are very much less dense than water, and yet it is towards these fluids of inferior density that water flows in endosmotic experiments. Alco- hol and ether have this in common with dense fluids generally, that they rise to a less height in capillary tubes than water. From this ob- servation I was led to imagine that the endos- motic current was always from the fluid having the greatest power of capillary ascension, to- wards the fluid having the least of this capa- city. It is true, indeed, as we have already seen, that alcohol proceeds by endosmosis to- wards water when the medium dividing them is caoutchouc. This would seem to say that alcohol would rise higher than water in capil- lary tubes of caoutchouc; and it is certain that caoutchouc has a greater attraction for alcohol than for water, inasmuch as the surface of India-rubber is much more readily wetted by alcohol than by water, which only adheres to it partially and imperfectly. This fact, there- fore, would not be in contradiction to my theory ; although I must confess that it is not reconcilable with certain endosmotic pheno- mena presented by the acids, as we shall imme- diately have occasion to perceive. In spite of this, however, I do not think I ought to pass ENDOSMOSIS. 103 in silence all the proofs that seem to establish this theory upon a basis of sufficient solidity ; for I cannot but perceive that it is applicable to the most general phenomena of endosmosis, phenomena, too, which the acids, like all other fluid bodies, exhibit, although they also present endosmotic phenomena in addition of a diffe- rent nature, and which belong to them exclu- sively. Inequality of density being one cause of en- dosmosis among fluids, it became a point with me first to ascertain what differences in power of capillary ascension resulted from determi- nate differences of density among fluids ; and next, to discover whether the difference in power of capillary ascent of two fluids bore any constant ratio to the difference of endos- mosis as it is proclaimed by experiment. The height to which different fluids rise in capillary tubes depends on a variety of causes, in appearance very different, but which must have some fundamental analogy. Of all fluids water is that which rises highest; and sub- stances held dissolved in it which increase its density, lessen its power of capillary ascent, which is also diminished by increase of tempe- rature : hot water ascends a less way in a capil- lary tube than cold water. Combustible fluids, such as alcohol and ether, are like dense fluids in regard to power of capillary ascent ; so that combustibility acts in the same manner as den- sity in this respect. The matter of which ca- pillary tubes are formed is also endowed with the power of modifying the capillary ascent of fluids. Thus water, at the same temperature, will not rise to the same height in a series of equal capillary tubes made of different mate- rials. These multiplied elements, which enter into the determination of the capillary ascend- ing power of different fluids, render it an ex- tremely complicated phenomenon. To simplify the study of this phenomenon in the greatest possible degree, let us confine ourselves to the use of two fluids, namely, water and a solution of the hydrochlorate of soda. It is easy to try the latter fluid of different densities, and to compare the power of capillary ascent pos- sessed by each of these with that of pure water at like temperatures. The same glass tube will answer for these comparative experiments. Be- fore detailing these experiments, however, I have one important remark to make, which is this; that the layer of fluid which moistens, internally, the canal of a tube is one of the elements of the capillary ascension which this tube effects. Thus, water will rise to a de- terminate height, in a tube interiorly moistened with water ; but if the interior of the tube be moistened by a saline solution, or by any other watery fluid, or by alcohol, pure water will not again rise so high in this tube as when it was moistened by water only. It will be in vain to attempt to cleanse the tube by passing water repeatedly through it ; water will never detach the stratum of saline or other liquid which ad- heres to it, and which diminishes its power of producing capillary ascension. To detach this stratum of fluid you must pass a filiform body repeatedly through the tube full of water ; it is only by the rubbing of this body that the stratum can be detached. It must be evident after this observation, that in making experiments on the power of capillary ascension with various fluids and with the same tube, it is necessary to cleanse this tube with great care before each experiment; without this we should have de- fective results. We must also take care not to warm the tube by holding it between the fingers, for if the temperature be increased it will no longer exert so strong a capillary attrac- tion. Let us now pass to the detail of these experiments. I prepared a solution of hydrochlorate of soda, the density of which was 1.12, the den- sity of the water being one. I took a part of this solution and to it added an equal volume of water, which gave it a density of 1.06. I had thus two saline solutions, of which the excess of density, above the density of water, was 0.12 and 0.06. The excess was thus in the relation of two to one. From my former experiments, these two excesses ought to serve as measures of the endosmosis produced by each of these saline solutions, put successively into the same endosmometer plunged in pure water. In fact, having submitted both of the saline solutions to experiment, I obtained from the most dense solution an endosmosis exactly double of that which was produced by the least dense solution. I next inquired into the rela- tion existing between the known density of these two saline solutions and water, and the power of capillary ascension possessed by the three fluids. I took a glass tube, whose capillary action raised water to the height of 12 lines at a temperature of + 10 degrees It. (50 Fahrenh.) I found that the same tube, at the same tem- perature, raised to 6j lines the solution of hydrochlorate of soda, the density of which was 1.12, and that it raised to 9^ lines the solution of the same salt, the density of which was 1.06. 1. The capillary ascension of the water being .... 12 The capillary ascension of the most dense fluid being 6 \ The excess of the capillary ascension of water is 5 1 2. The capillary ascension of water being ... 12 The capillary ascension of the least dense saline solution being 9 1 The excess of the capillary ascension of water is 2 1 Thus the two excesses of the capillary ascen- sion of water above the capillary ascension of each of these saline solutions are 5i| and 2^, or 4| and 2f. numbers which are in the relation of two to one, as are the two excesses 0.12 and 0.06 of the density of the two saline solutions above the density of water. Here, then, are two saline solutions which, put separately in relation to pure water, produce endosmosis intherelation of 2 to 1. Shall we refer this result to the 104 ENDOSMOSIS. circumstance that the excesses of density of each of these saline solutions over the density of water are in the ratio of 2 to 1, or to this, — that the excesses in the power of capillary ascent of each of these saline solutions over the power of capillary ascent of water are in the ratio of 2 to 1 ? In other words, is it the re- spective density of the two fluids which regu- lates or determines their endosmosis, or is it the respective powers of capillary ascension of the fluids severally ? The following experiment will solve this question. We have seen above that a solution of sulphate of soda and a solution of hydro- chlorate of soda of equal densities being put in relation to pure water, produce endosmoses which are in the relation of two to one. Here the difference of density does not interfere with the regulation of the endosmosis; we must then see if it be regulated by the power of capillary ascension. I prepared a solution of sulphate of soda and one of hy drochlorate of soda, having the same density 1.085, and tested their ca- pillary ascension in the same tube in which we have seen pure water raised to a height of 12 lines at a temperature of + 10 degrees R. I found that in the same tube and at the same temperature the capillary ascension of the so- lution of sulphate of soda was of 8 lines, and that of the solution of hydrochlorate of soda was of 10 lines. The excess of the capil- lary ascension of water above that of the solu- tion of sulphate of soda is consequently 4 ; the excess of the capillary ascension of water above the solution of hydrochlorate of soda is 2. These two excesses are in the relation of two to one, a relation which also measures the endosmosis produced with the concurrence of water by each of these two solutions of equal density. The result of this is that the capillary ascension, or power of capillary ascent, of fluids governs their endosmosis, and that their density only intervenes in this case as the determining cause of their capillary ascension. But how does the capillary action operate here ? This ap- pears to be difficult to determine. The capillary action never carries fluids out of the canals in which it takes place ; how then apply this action to the phenomenon of double permeation, which takes place in endosmosis and exosmosis ? This double permeation, which carries two he- terogeneous fluids towards each other, seems as though it were the result of the reciprocal attraction of the two fluids, of their tendency to associate by admixture. In experiments of endosmosis made with a dense fluid and water, the tendency to mix is favoured by the respec- tive positions of the two .fluids ; the dense fluid is above and the water below. This dis- position may possibly be one cause which fa- vours the reciprocal mixture of the two fluids, whose specific gravity would tend to place them in an inverse situation to that given them in the experiment. This does not take place when experiments on endosmosis are made with alcohol and water; then the alcohol, spe- cifically lighter than water, is situated above this latter fluid, and, notwithstanding this, the endosmosis is exceedingly energetic ; we must then acknowledge that the specific gravity of two fluids has not here the degree of influence that might be supposed to belong to it at first sight. We have consequently no means left to explain the course of the two fluids towards each other athwart the capillary canals of the parti- tion which separates them, but their reciprocal attraction or tendency to admixture. In ad- mitting that such is the efficient cause of this double permeation we must also necessarily admit that this efficient cause is governed in its operation by the capillary action of the par- tition. Here another question presents itself, — do the two fluids accomplish their admixture in the capillary canals themselves, or do they cross the partition by different capillary canals, so that neither fluid mixes with its opposite fluid until the moment of its exit from the capillary canals ? On the latter hypothesis it were necessary to admit that the number and diameter of the capillary canals followed sepa- rately by each of the two fluids must be per- fectly equal, for, without that, how would the general result of this double permeation, a result which is explained by the quantity of endosmo- sis, be in exact relation with the capillary action on the two fluids ? Now it is repugnant to reason to admit any such perfect equality among all the capillary canals, or to suppose an equal number especially fitted for the transmission of each of the two fluids. It must then necessarily be allowed that the transmission of the two op- posite fluids takes place by the same capillary canals, and that consequently this double movement of transmission takes place by a reciprocal penetration of the two fluids. The preceding theory, with which I was at one time inclined to rest satisfied, and which, indeed, seemed to be based on a sufficiently firm foundation, was however brought into jeo- pardy by a discovery which I made subse- quently, in regard to the phenomena of endos- mosis exhibited by certain acids separated from pure water by a layer of animal mem- brane. In the earliest experiments I made on the endosmosis of the acids, I observed a number of anomalous phenomena, for which I felt my- self incompetent to assign any sufficient reason. I had always placed the acids above the water, from which they were separated by a layer of animal membrane. Certain acids, such as the hydrochloric, at very different degrees of den- sity, and nitric acid only at pretty high degrees of density, gave me an endosmosis, the current of which was directed from the inferior water towards the superior acid, so that the acid rose gradually in the tube of the endosmometer. On the other hand, I had always found the sulphuric acid pretty largely diluted, and the hydrosulphuric acid, under the same circum- stances as the acids mentioned above, gradually to sink in the tube of the endosmometer. I con- cluded from this that, these acids did not occasion any endosmosis, and that they passed mechani- cally, and merely in virtue of their gravity, athwart the animal membrane to mingle with the water. I had also found that the sulphuric ENDOSMOSIS. 105 arid hydrosulphuric acids, added to gum-water, deprived it of the faculty of producing endos- mosis, and that this acidulated water fell in the tube of the endosmometer, instead of rising, as simple gum-water constantly does. These facts induced me to say metaphorically that the sul- phuric and hydrosulphuric acids were the ene- mies of endosmosis. More recent inquiries have enabled me to see the above mentioned phenomena in ano- ther light. It was the oxalic acid which led me to the conclusions I shall now lay be- fore the reader. Having poured a solution of this acid into the endosmometer closed with a piece of bladder, and placed the re- servoir m water, I found the acid fluid sink rapidly in the tube, and flow towards the inferior water, making its way by filtration through the animal membrane. I then reversed the arrangement observed in this experi- ment. I filled the endosmometer with water, and plunged the reservoir into a solution of oxalic acid. I was now surprised to find the water making its way rapidly into the endos- mometer, and the column rising in the tube, so that, in opposition to all I had yet observed, here was the current of endosmosis directed from the acid towards the water. The follow- ing are the particulars of this experiment. Having poured some rain-water into the reser- voir of the endosmometer, I plunged the reser- voir, closed with a piece of bladder, into a so- lution of oxalic acid of the density of 1.045, (11.6 parts of crystallized acid in 100 of the solution,) the temperature being + 25 cent. The ascent of the water in the tube of the en- dosmometer lasted for three days, becoming gradually slower and slower. The ascent hav- ing then become almost imperceptible, I emp- tied the endosmometer, in the contents of which I found water charged with oxalic acid. The exterior fluid was reduced in density to 1.033, so that, whilst the lower acid had pene- trated the upper water by endosmosis, the water had penetrated the acid by exosmosis, and thus diminished its density ; the permea- tion of the water, however, had been less con- siderable than that of the acid ; so that the upper water, increased in volume, had risen in the tube of the endosmometer. We have thus, in the present instance, another obvious proof of the existence of two opposite and unequal currents. Having filled the reservoir of the en- dosmometer anew with rain-water, I placed it in the solution of oxalic acid already used, and of the reduced density of 1.033. The ascent in the tube which again occurred, having almost ceased at the end of two days, I tested the fluid in the endosmometer, and found it to con- tain oxalic acid, and discovered the density of the external fluid further reduced to 1.025. I re- peated the same experiment a third time, filling the reservoir of the endosmometer with rain- water, and plunging it in the old acid solution. Endosmosis went on as before, but with less celerity. Having given up the experiment, after the lapse of twenty-four hours I found the density of the exterior fluid now reduced to 1.023, and the internal fluid to contain a por- tion of oxalic acid as before. I reduced the densi'y of the exterior acid solution to 1.01, but the included water still gave evidence of a pretty active endosmosis. I reduced the den- sity of the acid to 1.005, (1.2 of acid to 100 of the solution,) and the endosmosis was still very remarkable. In these experiments I found that the endosmosis was by so much the more rapid as the exterior acid solution was more dense, so that the capacity of oxalic acid to permeate an animal membrane would appear to increase with the density of its solution in water. In these experiments, too, we observe a fluid, more dense than water, and having a less power of capillary ascent than it, never- theless forming the stronger current, or current of endosmosis, whilst the water opposed to this fluid forms the iveukcr current, or counter-cur- rent of exosmosis. This is in opposition to all I had observed before ; and the theory I had raised on the different capacities of capillary ascent possessed by two opposed fluids is con- sequently shaken, or at all events proved to be no longer generally applicable. What may be the cause of this new phenomenon ? Do animal membranes give passage more readily through their meshes to solutions of oxalic acid than to water ? This point I sought to determine by the following experiments. The filtration of a fluid, by virtue of its gra- vity, through a porous lamina, the capillary canals of which are very minute, is not readily appreciable, unless the inferior or outer surface of this porous plate is kept plunged in or moistened by the same fluid. It is in this way only that the filtration of fluids through animal membranes, the texture of which is dense (a piece of bladder for example,) becomes appre- ciable. It is essential that the inferior aspect of the membrane be bathed with the same fluid as that which rests on its superior aspect, in order that no foreign cause modify its filtration. We know in fact that the heterogeneousness of two fluids, by producing endosmosis, would completely mask the effects of simple filtration. Would I, then, try the filtration of water through a membrane, I apply this membrane to an en- dosmometer, which I fill with water to a certain height in the tube of the instrument; I next apply the lower surface of this membrane to the surface of a body of water placed below it. The water contained in the endosmometer filters through the membrane and mingles with the water in the vessel below; the amount of this filtration in a given time is indicated by the fall of the column in the graduated tube of the instrument. Would I essay comparatively the filtration of any watery solution, I place this solution in the same endosmometer, and taking care to keep the exterior of the membranous part of the instrument in contact with a solution of the same nature, situated below it, I observe the degree to which the depression of the co- lumn in the tube takes place in a space of time equal to that which was taken by the filtration of the water. It is necessary to begin by proving the filtration of water; after this the filtration of the watery solution may be tried; but it is always to be borne in mind that the 106 ENDOSMOSIS. membrane of the endosmometer must have been kept plunged in the watery solution about to be experimented on for at least a quarter of an hour, in order that it may become tho- roughly impregnated with the solution, and to secure that this should take the place of the water which the membrane had formerly con- tained in its pores. Without this measure of precaution, the results of the second experi- ment would be faulty. It is also indispensa- ble that the circumstances under which the two experiments are performed are in all re- spects exactly alike. It was in this way that I proceeded to ascertain comparatively the capa- city of filtration of water to that of . a watery solution of oxalic acid through a piece of blad- der. I found that the filtrating power of rain- water, at the temperature of + 21 cent, being denoted by 24, the filtrating power of a watery solution of oxalic acid of no greater density than 1.005, (1.2 of acid to 100 of solution,) was denoted by 12. A solution of the same acid, of the density of 1 .01 , being tried, its filtrating power was found to be represented by 9. By these ex- periments it is therefore proved that water tra- verses an animal membrane more readily than a solution of oxalic acid. Why then does the latter solution traverse an animal membrane more readily and in greater quantity than water, when it is water which is in contact with the surface of the membrane opposite to that which is in contact with the acid ? This is a question which I find it impossible to answer in the present state of our knowledge. The discovery of this singular property of the oxalic acid to cause the endosmotic current to flow towards the water when separated from the latter fluid by a lamina of ammal mem- brane, led me to imagine that all the acids would be found to possess a similar property. And this I ascertained, in the first instance, to be the case in regard to the tartaric and citric acids. Both of these acids are much more so- luble in water than oxalic acid. The saturated solution of oxalic acid at + 25 cent, has no higher a density than 1.045 (11.6 acid to 100 of the solution.) But the solubility of the tar- taric and citric acids is such that their watery solutions may have a density of far greater amount. I tried the endosmotic effects of the tartaric and citric acids in watery solution of various density, and I discovered, not without surprise, that very dense solutions of them and solutions of inferior density exhibited endos- motic phenomena in inverse ratios. Thus, when a solution of tartaric acid was of a den- sity above 1.05, (11 crystallized acid in 100 of solution,) and it was divided from water by an animal membrane, the temperature being + 25 cent, the endosmotic current is directed from the water towards the acid ; but when, under the same circumstances, the density of the acid solution is below 1.05, the current of endos- mosis is directed from the acid towards the water, just as we have found it to be with refe- rence to the oxalic acid. Consequently, ac- cording to its greater or less density, tartaric acid presents the phenomenon of endosmosis in two opposite directions. At the mean density of 1.05, at a temperature of ■+• 25° cent, it exhibits no obvious endosmotic phenomena whatever ; not that there is not reciprocal pe- netration between the acid and the water, which are divided by the animal membrane ; but this reciprocal penetration takes place so equally on either side, that there is no increase of bulk of the one fluid at the cost of the other — there is no endosmosis. The citric acid exhibits pre- cisely the same phenomena ; the point of mean density, which divides its two opposed endos- motic capacities, is also very nearly the same, namely, 1 .05 at a temperature of -\- 25° cent. These facts induced me to imagine that if the oxalic acid alone presented the endosmotic cur- rent directed from the acid towards the water, this arose from the fact of its solution at + 25° cent, falling short of the density necessary to permit the acid solution to cause the endosmo- tic current to flow from the water towards the acid. The preceding observations were made during the heats of summer. The centigrade thermo- meter was standing at + 25° when I determined the mean term of density of the solution of tar- taric acid, above and short of which the endos- mosis happening between this solution and water is directed towards the acid. ..It was of importance to know whether a depression of temperature would cause any modification in these phenomena. I therefore repeated the same experiments when the temperature was 4-15° cent, and I was astonished to find that the mean term of density, of which we have spoken above, was considerably altered, being made to move in the direction of the increase of density of the acid solution. Thus the mean term of density being 1.05, (11 crystallized acid to 100 solution,) at a temperature of + 25° cent, it came to be 1.1, (21 acid to 100 solu- tion,) at a temperature of + 15° of the same scale ; that is to say, the solution of tartaric acid, which now occupies the mean term, con- tains nearly twice as much acid as the solution which stood at the previous mean term, when the temperature was ten degrees of the centi- grade scale higher. This first essay was enough to lead to the inference that the mean term of density, which we are now discussing, would undergo further alterations in the same sense with further depressions of temperature; and this was actually found to be the case. At a temperature of 8J° cent, the solution of tarta- ric acid, of the density 1.1, was no longer the solution of mean density dividing the two op- posed endosmotic currents, as it was when the temperature was + 15° cent. This solution then caused the endosmotic current to flow freely towards the water. I had to increase its density to 1.15 (30 acid to 100 solution) to come to the new mean term, beyond which the current of endosmosis was directed towards the acid, and within which it was directed towards the water. With the temperature depressed to a quarter of a degree cent, above zero, the solution of tartaric acid, of the density of 1.15, no longer presented the mean term ; this solution now occasioned endosmosis towards the water, which indicated that the mean term was to be ENDOSMOSIS. 107 sought for in a more dense solution of tartaric acid, and this I actually found in a solution of the density of 1.21 (40 acid to 100 solution). Every solution of this acid of greater density than 1.21, at the temperature of £th of a degree above zero cent, caused the endosmotic cur- rent to flow from the water towards the acid, and every solution of the same acid, under the density of 1.21, caused the endosmotic current from the acid towards the water. From all these experiments it follows that a fall of tem- perature favours the endosmosis towards the water, and that a rise of temperature favours the endosmosis towards the acid. Jn fact, the same solution of tartaric acid occasions at one time endosmosis towards the acid, when the temperature is high ; at another, endosmosis towards the water when the temperature is re- latively low. It would appear from this, that a depression of temperature renders the solu- tion of tartaric acid more apt than water to permeate animal membranes, and that there is a certain concordance between this capacity of permeation and the temperature and the den- sity of the acid solution. This phenonemon, at first sight, appears analogous to that which M. Girard discovered,* in regard to the com- parative flow of a solution of nitre and of pure water through a capillary glass tube. M. Girard found that, at a temperature of +10°, a solu- tion of one part of nitrate of potash in three parts of water flows more rapidly than pure water through a capillary glass tube, whilst the same solution flows more slowly than water when the temperature is above -|- 10°. To discover whether this apparent analogy was well founded or not, I made an experiment to ascertain the relative duration of the flow through a capillary glass tube of a given mea- sure of pure water, and a like measure of a solution of tartaric acid, the density of which was 1.05 (21.8 parts acid, 100 solution.) The temperature being + 7° cent. I found that fifteen centilitres of water flowed through a ca- pillary glass tube in 157 seconds; but the same quantity of the solution of tartaric acid required 301 seconds to pass through the same capillary tube. There is consequently no ac- tual analogy to be established between the re- sults of the experiments of M. Girard and the fact of the endosmosis towards the water, which takes place when at a temperature of +7° cent, a solution of tartaric acid of the den- sity of 1.105, is separated from a volume of pure water by a piece of an animal membrane. It may be as well if I here state that when a solution of one part of nitrate of potash in three parts of water was separated by a piece of bladder from pure water, I have always ob- served the endosmotic current directed towards the solution ; the temperature might be at zero, or -J- 10°, or higher, the same phenome- non always occurred. This is sufficient to prove that endosmosis is governed by laws en- tirely different from those that preside over simple capillary filtration. I add, that the solution of tartaric acid, of 1.105 density, hav- ' Mem. de l'Acud. des Sciences, 1816. ing a viscidity nearly the double of that of water, and passing, nevertheless, by endosmo- sis into the latter fluid, when it is separated from it by an animal membrane, and the tem- perature is + 7° cent, also proves that endos- mosis does not generally depend on the visci- dity of fluids. Acid solutions are the only fluids which have yet been found to occasion the endosmotic cur- rent to flow towards water when separated from this fluid by an animal membrane. The whole of the acids, without exception, exhibit this phenomenon, which was long overlooked by me, from its having been confounded with another phenomenon, namely, the abolition of endosmosis. I have in fact shown, in a work already before the public,* that all fluids which act chemically on the membrane of the endos- mometer, put an end, with greater or less cele- rity, to the phenomenon of endosmosis, — it goes on for some time, but it never fails to cease at length. Sulphuric acid, above all the other acids, has the property of putting an end to endosmosis. This acid, poured into the en- dosmometer, sinks by virtue of its simple gravity towards the lower water, filtering mechanically through the membrane placed between it and the water. If the position of the two fluids be reversed, the endosmometer being charged with water, and the sulphuric acid placed externally and on the lower level, the water still sinks to- wards the acid, passing in its turn mechani- cally through the membranous septum of the instrument, rendered incapable of effecting en- dosmosis. From these experiments I was led at first to conclude that sulphuric acid was in- active as regards endosmosis ; in other words, was incapable of exhibiting or producing this phenomenon. I have since found, however, that the sulphuric, like all the other acids, has the faculty of exerting endosmosis in the two opposite directions, but always during a very brief space of time only. Thus the tempera- ture being + 10° cent., sulphuric acid, of the density of 1.093, separated from water by a piece of bladder, the endosmotic current is directed from the water towards the acid, but the phenomenon lasts only for a short time ; the current soon ceases, and if the acid be on the higher level, it then begins to sink by sim- ple mechanical filtration towards the water. At the same temperature of + 10° cent., the sulphuric acid attenuated to 1.054 being placed in the endosmometer, and the reservoir and a part of the tube being plunged in water, en- dosmosis is established, but in this case the current is from the acid towards the water, so that the acid liquor sinks in the tube ; and that this sinking is due to endosmosis is demon- strated by the fact of the acid continuing to sink in the tube of the endosmometer a consi- derable way below the level of the external water, and not stopping short when the level is obtained, as it does when the descent is owing to simple mechanical filtration. In this expe- riment, as in the one detailed immediately be- * Nouv. Redhetches sur l'Emlosmose, &c. p. 25. See also my Memoir in the 49th vol. of the Annates de Chimie, p. 415. 108 ENDOSMOSIS. fore it, the endosmosis towards the water is abolished, and then the column in the endos- mometer begins to rise again slowly, until the level of the external and included fluids corre- spond. We, therefore, see that at a tempera- ture of + 10° cent., sulphuric acid, of the density of 1.093, presents the current of endos- mosis from the water towards the acid ; whilst the density being 1.054, the endosmosis is from the acid towards the water. Between these two opposite endosmotic currents there necessarily exists a mean when no phenomena of the kind occur. This mean, the tempera- ture continuing 10°, I find to belong to sul- phuric acid of the density of 1.07. The two fluids, divided by the animal membrane of the endosmometer, penetrate one another athwart the septum reciprocally and in equal measure, so that the contents of the endosmometer re- main for a certain time at the same height in the tube of the instrument ; subsequently the contained fluid begins to sink in consequence of the cessation of all endosmosis. These ex- periments were necessarily undertaken when the temperature was mpderate or low ; the phenomena detailed would not else have been appreciable ; for in a warm atmosphere the abolition of endosmosis by sulphuric acid is accomplished so rapidly, that it is with diffi- culty the slight current established in the first instance can be observed. Sulphurous acid, of the density 1.02, sepa- rated from water by an animal membrane, only exhibits endosmosis towards the water ; this endosmosis is pretty active at first ; but after the lapse of a brief interval the current ceases, just as it does with the sulphuric acid. These results I came to after a number of experi- ments, the temperature being at one time + 5°, and at another +25° cent. Formerly I regarded the hydrosulphuric acid as inactive in regard to endosmosis ; I assimi- lated it, in this respect, with the sulphuric acid. The fact, however, is that, like the sulphuric acid, it has the property of producing endos- mosis. The acid I employed was of the den- sity of 1 .00628. With a piece of bladder be- tween this acid and water, the endosmosis was constantly towards the water. This conclusion was not influenced by variations of tempera- ture between -j- 4° and -f- 25° cent. The ac- tion was somewhat protracted, but the endos- mosis never failed to cease after a certain time, as in the case of the sulphuric acid. The nitric acid of considerable density exhi- bits endosmosis towards the acid when sepa- rated from water by a piece of animal mem- brane. Thus, at a temperature of +10° cent, this acid (density 1.12 or higher) presents the current flowing towards the acid. Under the same circumstances, but of the density of 1.08, the endosmosis is towards the water. Of the density 1.09, the mean term between the two opposite endosmoses is obtained. At higher temperatures the nitric acid very speedily puts an end to the phenomena of endosmosis, espe- cially when its density is not very high, so that it becomes difficult to perceive the very tran- sient currents produced in the first instance. The hydrochloric is the most potent of all the mineral acids in directing the current of endosmosis from the water towards the acid. Its density must be considerably reduced before it. offers the direction of the current changed, or from the acid towards the water. At a tempe- rature of 4- 22° cent, for instance, the hydro- chloric acid has to be brought, by the addition of water, to a density no higher than 1.003, before it presents the endosmosis flowing to- wards the water, from which, as understood, it is divided by a layer of animal membrane. Of greater density the endosmosis is towards the acid. When the temperature is lower than + 22°, the same acid, of greater density, ac- quires the property of causing endosmosis to- wards the water. Thus, with the centigrade thermometer at + 10°, I found that hydro- chloric acid of 1.017 density presented the mean term between the two opposite endosmo- ses. At the same temperature hydrochloric acid, of 1.02 density, presented endosmosis to- wards the acid, and of 1.015 density, endos- mosis towards the water. Under a higher temperature, however, and of the latter density (1.015), the endosmosis was towards the water, so that a depression of 12° cent, in tem- perature causes the mean term of the density of hydrochloric acid, which separates the two op- posed endosmoses, to rise from that of about 1.003 to that of 1.027; that is to say, the quantity of acid added to the water must be increased almost six-fold to produce the same effects. In the present state of our knowledge, we find it quite impossible to give any explanation of the remarkable phenomenon exhibited in the changes of direction of the endosmotic currents according to the degree of density of the acid and the temperature. The singularity of this phenomenon will appear the greater when the following observation is taken into the account. Hitherto it was always by a layer of animal membrane that I separated the acid from the water. Instead of the animal membrane I now tried the effect of one of vegetable origin. We have seen above that oxalic acid, whatever its density and under whatever temperature, when separated from water by an animal mem- brane, always exhibited endosmosis from the acid towards the water. I filled a pod of the colutea arborexcens, which being opened at one end only and forming a little bag, was readily attached by means of a ligature to a glass tube, with a solution of oxalic acid, and having plunged it into rain-water, endosmosis was ma- nifested by the ascent of the contained acid fluid in the tube ; that is to say, the current flowed from the water towards the acid. The lower part of the leek ( allium porrum ) is en- veloped or sheathed by the tubular petioles of the leaves. By slitting these cylindrical tubes down one side, vegetable membranous webs, of sufficient breadth and strength to be tied upon the reservoir of an endosmometer, are readily obtained. An endosmometer, fitted with one of these vegetable membranes, having been filled with a solution of oxalic acid, and then plunged into rain-water, the included fluid rose ENDOSMOSIS. 109 gradually in the tube of the endosmometer, so that the endosmosis was from the water towards the acid, the reverse of that which takes place when the endosmometer is furnished with an animal membrane. The tartaric and citric acids of densities below 1.05, and at a tempe- rature of + 25° cent, exhibit endosmosis to- wards the water with an animal membrane ; but with a vegetable membrane the case is altered ; the endosmosis being then directed from the water towards the acid. I have tried solutions of tartaric acid, decreasing gradually in density from 1.05 (11 tartaric acid to 100 solution) to a density so low as 1.0004, (1 tar- taric acid, 1000 solution,) and always seen the endosmosis towards the acid. A gradual fall in the temperature from -J- 25° to near zero did not affect the result. Sulphuric acid of 1.0274 density and at a temperature of ■+■ 4° centes. when separated from water by a vegetable membrane, exhibited endosmosis towards the acid ; separated by an animal membrane, however, the endosmosis was towards the water. Hydrosulphuric acid (density 1.00628) sepa- rated from water by an animal membrane, always shows endosmosis towards the water ; but separated by a vegetable membrane, the current is as uniformly towards the acid. The experiment from which I deduce this result was only performed at a temperature of -j- 5°. Sulphurous acid (density 1.02) separated from water by an animal membrane, exhibits an active endosmosis towards the water, at every temperature from zero up to + 25° centes. (I have made no experiments on endosmosis at higher temperatures.) When sulphurous acid, of the density of 1.02, is separated from water by a layer of vegetable membrane, it presents neither endosmosis towards the acid nor endos- mosis towards the water ; it then appears to be under the influence of the simple laws presiding over the flow of fluids by filtration : there is abolition of endosmosis. [ was anxious to see what endosmotic effects it would produce with an endosmometer closed with a layer of baked clay, and it was not without surprise that I saw the current flowing vigorously towards the water. I had put the acid into the reservoir of the endosmometer; and the included fluid rose to a considerable height in the tube of the in- strument, which I had taken care to immerse in water to the place where the acid rose in the tube. The acid continued to sink in the tube of the endosmometer for four hours, and had then fallen to about 12 centimetres below the level of the external water ; it subsequently be- gan to rise slowly in the tube, and finally gained the level of the external water, where it remained. It was obvious that the sulphurous acid had sunk in the tube below the level of the water, in consequence of endosmosis towards the water, and that its subsequent rise to the level of the water was due to simple filtration through the membrane. Endosmosis had then ceased. Sulphuric acid, diluted with water to the den- sity of 1.0549, exhibits the same phenomena as sulphurous acid when separated from water by a lamina of baked clay : it first occasions en- dosmosis towards the water, but after some minutes this endosmosis ceases, and is not re- placed by endosmosis of an opposite nature ; simple filtration from the effect of gravity is all that then takes place; endosmosis of each kind is put a stop to. Hydrosulphuric acid, sepa- rated from water by a lamina of baked clay, gives the same results precisely as the sulphu- ric acid. This phenomenon is rendered still more strange by the fact of its not being general. Thus the oxalic acid exhibits endosmosis to- wards the acid when this is separated from water by a lamina of baked clay. This fact I ascertained under a variety of temperatures from + 4° to + 25° centes. and with solutions of the acid of as great density as could be ob- tained at each temperature, as well as with so- lutions of very low density. The tartaric acid also presents endosmosis towards the acid when separated from water by a lamina of baked clay. I had formerly found * that a little sul- phuric or hydrosulphuric acid added to gum- water, causes the current of endosmosis to cease flowing from the water towards the gum-water, so that the latter fluid, instead of rising in the tube of the endosmometer, begins gradually to fall. I then attributed this phenomenon to the abolition of endosmosis ; but it is evident that in certain cases it is owing to the current of en- dosmosis changing its direction and flowing from the acid towards the water. Thus, with reference to the acidulated gum-water, of which I have just spoken, when placed above water, from which it was separated by an animal membrane, it fell in the stem of the endosmo- meter and flowed towards the water, either from the abolition of endosmosis, and in virtue of its gravity, or in consequence of the establishment of an endosmotic current towards the external water. Experiment can alone determine which of these two causes is the efficient one of the descent of the acidulated fluid in the stem of the endosmometer. The whole of the acids used of such density as comports with the pro- duction of endosmosis towards water, and in sufficient quantity, are adequate to overcome the disposition which any fluid may possess to produce endosmosis in the opposite direction. Here is a case in illustration of this point. The power of sugar-water in causing endosmosis is very great, as I have shown already. Water holding no more than one-sixteenth of its weight of sugar in solution causes rapid endos- mosis from the water towards the solution. But I have found that, by adding to this sweet liquid a quantity of oxalic acid equal in weight to that of the sugar which it holds in solution, the direction of the endosmotic current is im- mediately changed ; the flow is no longer from the water towards the solution, but from the sweet-sour solution towards the water, so that the oxalic acid may be said to compel the sac- charine solution to which it is added to take the direction of the endosmotic current which is proper to it. Here it is the viscid and dense fluid, with little power of capillary ascent, which traverses the animal membrane with * Nouv. Rech. sur l'Endosmose, p. 8. 110 ENDOSMOSIS. greater ease and more rapidity than pure water. This may be added to the facts set forth already to prove, in the most decided manner, that the greater power of permeation manifested by one of the two fluids in experiments on endosmosis does not follow from any greater viscidity it may possess than the fluid opposed to it. In sixteen parts of water I dissolved two parts of sugar and one part of oxalic acid. In this so- lution I plunged the reservoir of an endosmo- meter, closed with a piece of bladder, and filled with pure water : this did not show any diffe- rence of level in the tube during the two hours that I continued the experiment. There was consequently no endosmosis. Nevertheless, I found that the water contained in the endosmo- meter contained a large quantity of oxalic acid, whether tested by the addition of lime-water or by the palate, which last also detected the presence of sugar. Thus the sweet-sour fluid, exterior to the endosmometer, had penetrated the water contained within its cavity. If this circumstance was proclaimed by no increase in the volume of the water, this undoubtedly was owing to the included water having lost by the descending counter-current an amount exactly equal to the amount it had gained by the in- ward or ascending current. There was no en- dosmosis in the sense in which I use that word, although it is certain that there were two active antagonist currents athwart the membrane which separated the two fluids. It must not be lost sight of that I only give the title of endosmosis to a stronger current opposed to a weaker counter-current, antagonists to each other, and proceeding simultaneously athwart the septum, dividing the two fluids which are made the subjects of experiment. The instant these two antagonist currents become equal, there is no accumulation of fluid on one side, and there is then no longer any effort at dilatation or im- pulsion ; in a word, there is no longer any endosmosis. The opposite directions in which the endos- mosis towards water, effected by acids of deter- minate density, and the endosmosis from water occasioned by other fluids, would lead us to conclude that in placing such a fluid as gum- water or sugar-water in an endosmometer fur- nished with an animal membrane, and in con- tact externally with an acid solution of appro- priate density, we should have a much more rapid endosmosis towards the included fluid than if it were pure water in which the endos- mometer was plunged ; and this in fact is what I have found to be the case by experiment. Into an endosmometer, closed with a piece of bladder, I poured a solution of five parts of sugar in twenty-four parts of water. .Having plunged the reservoir of the instrument into water, I obtained in the course of an hour an ascent of the included fluid, which may be re- presented by the number 9. The reservoir of the same endosmometer filled with a portion of the same saccharine solution, having been plunged into a solution of oxalic acid, the den- sity of which was 1.014, (3.2 parts acid to 100 solution,) I obtained in the course of an hour an ascent of the included fluid, which required to be represented by the number 27. The substitution of a solution of oxalic acid for pure water consequently caused the amount of endosmosis in the same interval of time to be tripled. I obtained like results with the tarta- ric and citric acids, employed of the densities required to enable them to produce endosmosis towards water. From these experiments it would appear that water, charged with a small proportion of one of the acids, of which men- tion has been made, possesses a power of pene- tration athwart animal membranes greater than that inherent in pure water. But a direct ex- periment, detailed in an earlier part of this paper, proves that this is not the case ; pure water used by itself is still the fluid that pos- sesses the greatest power of penetrating through animal membranes. If, consequently, in those experiments which I have last described, the water charged with acid passed more readily and more copiously into the saccharine solu- tion than pure water, this happens undoubtedly from other causes or conditions which I cannot take upon me to explain, but which appear to be : 1st. A reciprocal action between the two heterogeneous fluids, an action which modifies, which even completely inverts the natural power of penetration possessed by each of the fluids when employed singly ; 2d. % particular action of the membrane upon the two fluids which penetrate it, an action which, with the animal membrane, gives the stronger current or current of endosmosis to the acid solution of due density, and the weaker current or coun- ter-current of exosmosis to the pure water. It seems to me impossible to deny this peculiar action to the animal membrane, when we see that a vegetable membrane in the same circum- stances produces endosmotic phenomena di- rectly the reverse. The peculiar influence of the membranous septum is likewise manifested in a very striking way in the experiment in which I have shown that the current of endos- mosis flows from water towards alcohol when these two fluids are divided by an animal membrane, and, on the contrary, that the cur- rent of endosmosis flows from alcohol towards water when the two fluids are separated by a membranous septum of caoutchouc. Endosmosis, in the present order of things, is a phenomenon restricted to the realm of or- ganization ; it is nowhere observed in the inor- ganic world. It is in fact only among organ- ized beings that we observe fluids of different density separated by thin septa and capillary pores ; we meet with nothing of the same kind among inorganic bodies. Endosmosis, then, is a physical phenomenon inherent exclusively in organic bodies, and observation teaches us that this phenomenon plays a part of the high- est importance in their economy. It is among vegetables especially that the importance of the phenomenon strikes us ; I have, in fact, de- monstrated that it is to endosmosis that are due, in great part, the motions of the sap, and particularly its very energetic ascending motion. I have also shown that all the spontaneous mo- tions of vegetables are referable to endosmosis. The organic vegetable tissue is composed of a ENTOZOA. Ill multitude of agglomerated cells mingled with tubes. The whole of these hollow organs, the parietes of which are extremely thin, and which contain fluids the densities of which vary, ne- cessarily make mutual exchanges of their con- tents by way of endosmosis and exosmosis. Nor can we suppose but that the same pheno- mena take place among the various cells and cavities exhibited by the organism of animals. But the effects of endosmosis, its influence on the physiological phenomena presented by ani- mals, has yet to be determined ; and here, un- doubtedly, the physiologist has an ample field before him for inquiry. I shall only say in conclusion, and with reference to this very in- teresting part of the subject, that I have satis- fied myself that it is to endosmosis that the motions of the well-known spiral spring tubes of the milt of the cuttle-fish, when put into water, are owing. (H. Dutrochet.) ENTOZOA, (euto?, intus, tpov, animal,) eA/aikGe; crrgoyyvhoi, eA^ivQe; wXcnuca, ctcry.a.- £»Je;, Arist. et Antiq. Vers Intestinaux, Cuv. Entelmintha, Splanchnelmintha, Zeder. The term Entozoa, like the term Infusoria, is indicative of a series of animals, associated together chiefly in consequence of a similarity of local habitation ; which in the present class is the internal parts of animals. In treating therefore of the organization of these parasites, we are compelled to consider them, not as a class of animals established on any common, exclusive, or intelligible cha- racters, but as the inhabitants of a peculiar dis- trict or country. They do not, indeed, present the types of so many distinct groups as those into which the naturalist finds it necessary to distribute the subjects of a local Fauna, yet they can as little be regarded as constituting one natural assem- blage in the system of Animated Nature. And it may be further observed that as the members of no single class of animals are con- fined to one particular country, so neither are the differgfit natural groups of Entozoa exclu- sivelv^jepresented by species parasitic in the interior of animal bodies. Few zoologists, we apprehend, would dissociate and place in sepa- rate classes, in any system professing to set forth the natural affinities of the animal king- dom, the P lunar ia from the Tremutoda, or the Vibrioniclce from the microscopic parasite of the human muscles. In the present article it is proposed to divide the various animals confounded together under the common term of Entozoa or Entelmintha into three primary groups or classes; and, as in speaking of the traits of organization common to each, it becomes not only convenient but necessary to have terms for the groups so spoken of, they will be denominated Protel- mint/ia, Sterelmintha, and Ccelelmintha respec- tively. It may be observed that each of these groups, which here follow one another in the order of their respective superiority or com- plexity of organization, has been indicated, and more or less accurately defined by pre- vious zoologists. After the dismemberment of the Infusoria of Cuvier into the classes Polygastrica and Kotifera, which resulted from the researches of Professor Ehrenberg into the structure of these microscopic beings, there remained certain families of Animalcules which could not be definitely classed with either : these were the Cercariadce and Vibrio- nida. Mr. Pritchard, in his very useful work on Animalcules, has applied to the latter fa- mily the term Entozoa, from the analogy of their external form to the ordinary species of intestinal worms ; and it is somewhat singular that a species referrible to the Vibrionidce should subsequently have been detected in the human body itself. Premising that the tribe Vibrionidie as at present constituted is by no means a natural group, and that some of the higher organized genera, as Anguillula, are re- ferrible to the highest rather than the lowest of the classes of Entozoa, we join the lower organ- ized genera, which have no distinct oviducts, and which, like the parasitic Trichina, resemble the foetal stage of the Nematoid worms, with the Cercariada, in which the generative apparatus is equally inconspicuous; and these families, dismembered from the Infusoria of Lamarck, constitute the class Protelmintha, the first or earliest forms of Entozoa. The second and third classes correspond to the two divisions of the class Intestinalia, in the ' Regne Animal ' of Cuvier, and which are there respectively denominated ' Vers Intesti- naux Parenchymateux,' and ' Vers Intestinaux Cavitaires.' The characters of these classes will be fully considered hereafter; and in the mean- while but little apology seems necessary for in- venting names expressive of the leading distinc- tion of each group as Latin equivalents for the compound French phrases by which they have hitherto been designated. Etyu>s, forma.) Vermes taniaformes, Bandwurmer, Tape-worms. Char. Body elongated, flattened, soft, continuous, or articulated. Head either simply labiate, or provided with pits (bothria) or suctorious orifices (oscula suctoria) either two or four in number, and sometimes with four retractile un- armed or uncinated tentacles. Andro- gynous generative organs. Obs. In this order Rudolphi includes the inarticulated Ligula, with simple heads un- provided with bothria or suckers; a conjunc- tion which detracts from the natural character of the group. Cuvier separates the Ligula from the Tania, and they form exclusively his Order Cestoidea ; it must be observed, however, that the passage from the one to the other is rendered very gradual by the traces of bothria, and of generative organs which appear in the higher organized Ligula found in the intestines of Birds ; and respecting which Rudolphi hazards the theory that they are the more simple Ligula of Fishes, developed into a higher grade of structure by the warmth and abundant nutri- ment which they meet with in the intestines of Birds which have swallowed the Fishes infested by them. Oudo III. Them atoda, (T^fta, foramen, r^ri/ji.cc.TaS'rii foraminosus.) Vermes suctorii, Saugwurmer, Fluke- worms. Char. Body soft, rounded, or flattened. Head indistinct, with a suctorious fo- ramen ; generally one or more suctorious cavities for adhesion in different parts of the body. Organs of' both sexes in each individual. Obs. This very natural order includes, in the system of Cuvier, many species which do not infest other animals, but are found only in fresh waters ; these non-parasitic species form the greater part of the genus Planaria of Muller, (Jig. 80.) Rudolphi, who seems to have sup- posed the Planaria to be of a more simple organization than they truly possess, approxi- mates them to the Ligulas or inarticulated Ces- toidea. Other naturalists, unwilling to asso- ciate the Planaria with the Entozoa, have placed them in the Class Anellida, but the absence of a ganglionic abdominal nervous chord, of a floating intestine, and of an anus, renders such an association very arbitrary. Ordo IV. Acanthocepuala, (a.jca>6a, spina, x.i$a.\-n, caput.) Vermes uncinati, Haeken-wvrmer, Hooked-woi^ms. Char. Body elongated, round, sub-elas- tic. Head with a retractile proboscis armed with recurved spines, (Jig. 74.) Sexual Organs appropriated to distinct individuals, male and female. Obs. This natural group includes the most noxious of the internal parasites ; fortunately no species is known to infest the human body. They abound in the lower animals, and present great diversity of form, some being cylindrical and others sacciform. OrdoV. Nematoidea, (iD^a.,Jilum, ei^oj, forma.) Vermes teretes, Rund-w'urmer. Round- worms. Char. Body elongated, rounded, elastic. Mouth variously organized according to the genera. A true intestinal canal terminating by a distinct anus. Sexes distinct. Obs. The internal character which Rudolphi has introduced in his definition of this Order,* viz. that derived from the structure of the ali- mentary canal, its free course through the body, and its termination by a distinct anus at the extremity opposite the mouth, is one of much greater value than any of the external modifica- tions of the body which characterize the four preceding orders. It is, in fact, a trait of or- ganization which is accompanied by corre- sponding modifications of other important parts, more especially the nervous system. The Entozoa which manifest this higher type of structure form in the syslem of Cuvier a group equivalent to that which is constituted by the four other orders combined. The En- tozoa composing the first four orders above characterized have no distinct abdominal cavity or intestine,but the digestive function is carried on in canals without an anal outlet excavated in the parenchymatous substance of the body, and Cuvier accordingly denominates them the Vers intestinaux parenchymateux. The Ne- matoidea, with which Cuvier rightly associates the genus Pentastoma of Rudolphi, and also (but less naturally) the Vers rigidules of La- marck, or Epizoa, he denominates ' Vers intes- tinaux cavitaires.' With respect to the Epizoa, or the external Lerna?an parasites of Fishes, although they agree with the Nematoidea and all inferior Entozoa in the absence of distinct respiratory organs, yet the ciliated natatory members which they possess in the young state, and the exter- nal ovarian appendages of the adult, are cha- racters which raise them above the Entozoa as a distinct and higher class of animals, having intimate relations with the soft-skinned Sipho- nostomous Crustaceans. Limiting, then, the Cavitary Entozoa to the Nematoidea of Rudolphi, and the Genera Lin- guatula, Pentastoma, Porocephulus, and Syn- gamus, which, under the habit of Cestoid or Trematode Worms, mask a higher grade of organization, we propose to regard them as a group equivalent to the Sterelmintha, and to retain for them the name of Ctzlelmintha. The class of Entozoa thus constituted em- braces already the types of three different orders, of which one is formed by the Nema- toidea of Rudolphi, a second has been esta- blished by Diesing for the genus Pentastoma and its congeneric forms, under the name of * " Corpus teres elasticum, tractus intestinalis hinc ore, illinc ano terminatus. Alia individua mascula, alia feminea. "Synops. Entox. p. 3. ENTOZOA. 117 Acanthotheca ; and the singular organization of the Syngamus of Siebold, presently to be described, clearly indicates the type of a third order of Cavitary Entozoa. As a short description has already been given of the species of Protelmintha which inhabit the human body, we shall proceed to notice those species belonging to the two di- visions of Entozoa above defined, which have a similar locality, before entering upon the organization of the class generally. The first and simplest parasite which de- mands our attention is the common globular Hydatid, which is frequently developed in the substance of the liver, kidney, or other abdo- minal viscera, and occasionally exists in prodi- gious numbers in dropsical cysts in the human subject. Considerable diversity of opinion still exists as to the nature of these ambiguous productions, to which Laennec first gave the name of Ace- phalocysts ; we shall nevertheless admit them into the category of human parasites, for reasons which are stated in the following descrip- tion. The Acephalocyst is an organized being, consisting of a globular bag, which is com- posed of condensed albuminous matter, of a laminated texture, and contains a limpid co- lourless fluid, with a little albuminous and a greater proportion of gelatinous substance. The properties by which we recognize the Acephalocyst as an independent or individual organized being are, first, growth, by intrinsic power of imbibition ; and, secondly, reproduc- tion of its species by gemmation. The young Acephalocysts are developed between the layers of the parent cyst, and thrown off either inter- nally or externally according to the species. As the best observers agree in stating that the Acephalocyst is impassive under the appli- cation of stimuli of any kind, and manifests no contractile power either partial or general, save such as evidently results from elasticity, in short, neither feels nor moves, it cannot, as the animal kingdom is at present characterized, be referred to that division of organic nature. It would then be a question how far its chemical composition forbids us to rank the Acephalocyst among vegetables. In this king- dom it would obviously take place next those simple and minute vesicles, which, in the aggregate, constitute the green matter of Priestly, ( Protococcus viridis, Agardh ;) or those equally simple but differently coloured Psychodiaria, which give rise to the red snow of the Arctic regions, (Protococcus Ker- mesianus.) These " first-born of Flora'' con- sist in fact of a simple transparent cyst, and propagate their kind by gemmules developed from the external surface of the parent. Or shall we, from the accidental circum- stance of the Acephalocyst being developed in the interior of animal bodies, regard it, as Rudolphi would persuade, in the same light as an ulcer, or pustule, — as a mere morbid pro- duct? The reasons assigned by the learned Pro- Acephalocystis endogena. fessor* do induce us to consider the Acephalo- cyst as a being far inferior in the scale of orga- nization to the Cysticercus; but still not the less as an independent organized species, sharing its place of development and sphere of existence in common with the rest of the Entozoa. Acephulocystis endogena. Pill-box Hydatid of Hunter, (fig. 56). This species is so called from the circum- Fig. 56. stance of the gem- mules being detach- ed from the internal surface of the cyst, where they grow, and, in like man- ner, propagate their kind, so that the successive genera- tions produce the appearance descri- bed by Hunter and other pathologists. The membrane of the cyst is thin, delicate, transparent, or with a certain pearly semi-opacity; it tears readily and equally in every direction, and can, in large specimens, be separated into lamina;. The phenomenon of endosmose is readily seen by placing the recent Acepha- locyst in a coloured liquid, little streams of which are gradually transmitted and mingle with the fluid of the parasite. The vesicles or gemmules, developed in the parietes of the cyst, may be observed of different sizes, some of microscopic dimensions, others of a line in diameter before they are cast off, see fig. 56, where a shows the laminated membrane, b the minute Acephalocysts developed between its layers. The Acephalocyst of the Ox and other Ru- minant Animals differs from that of the Hu- man Subject in excluding the gemmule from the external surface, whence the species is termed Acephulocystis exogena by Kuril. Both kinds are contained in an adventitious cyst, com- posed of the condensed cellular substance of the organ in which they are developed. The Genus Echinococcus is admitted by Rudolphi into the Order Cystica, less on ac- count of the external globular cyst, which, like the Acephalocyst, is unprovided with a head or mouth, than from the structure of the minute bodies which it contains, and which are described as possessing the armed and suctorious head characteristic of the Ccenuri and Cysticerci. It must be ob- served that Rudolphi-f does not ascribe this * Mihi, quidem, ea tandem hydatis animal vivum vocatur, qua? vitam propriam degit uti Cys- ticerci, Coenuri, &c. Quae autem organismi alieni ( v. c. humani) particulum efficit animal, me judice, dici nequit. Mortua non est, quamdiu organismi partem sistit, uti etiam ulcus, pustula, efflorescentia ; sed haec ideo non sunt animalia. — ■ Synops. Entoz. p. 551. t Vermiculi globosi, subglobosi, obovati, obcor- dati, etc.; pro capite plus minus vel exserto vel rctracto; posticc mox obtusissimi, mox obtusi, mox acuti. Corona uncinulorum, uti vidctur, duplex. 118 ENTOZOA. complicated structure to the vermiculi of the Human Echinococcus on his own authority, and speaks doubtfully respecting the coronet of hooklets and suctorious mouths of the ver- miculi contained in the cyst of the Echinococcus of the Sheep, Hog, &c. The Echinococcus hominis, (Jig. 57,) which occurs in cysts in the Fig. 57. liver, spleen, omen- tum, or mesentery, is composed ofan exter- nal yellow coriace- ous, sometimes crus- taceous tunic, and an internal transparent, firm, gelatinous membrane. The form of the contained ver- miculi is represented in the magnified view subjoined, (fig. 58,) taken from the Elminto- grafia humuna of Delle Chiaje. Fig. 58. Echinococcus hominis. Vermictcfi ofi Echinococcus hominis, highly magnified Miiller*\fe!&. recently described a species of Echinococ^svgaded with the urine by a young man labouring under symptoms of renal disease. The tunfe of the containing cyst was a thick white membrane, not naturally divided into laminse; th&Wiimalcules floating in the con- tained fluid presented a circle of hooklets and four obtuse processes round the head ; the pos- terior end of the body obtuse : some of thenj were inclosed in small vesicles floating in the large one ; others presented a filamentary pro- cess at their obtuse end, probably a connecting pedicle which had been broken through. Of the species entitled Echinococcus veteri- norum we have carefully examined several in- dividuals soon after they were extracted from the recently-killed animal, (a sow, in which they existed in great abundance in cysts in the abdomen.) The containing cysts were com- posed of two layers, artificially separable, both of a gelatinous texture, nearly colourless and subtransparent, the external one being the firmest. The contained fluid was colourless and limpid, with a few granular bodies floating Oscula suetoria quatuor ; an haec in omnibus ? Ipse saltern in suis Echinococcis non vidi, set! dum Be- rolini recens examinarem, microscopio solito et bono destitutes erara. —Hist. Entoz. * Archiv fur Physiol. (Jahresbcricht), 1836. in it, and immense numbers of extremely mi- nute particles applied but not adherent to the internal surface of the cyst. On examining these particles with a high magnifying power, they were seen to be living animalcules of an ovate form, moving freely by means of superfi- cial vibratile cilia, having an orifice at the smaller end from which a granular and glairy substance was occasionally discharged, and a trilobate de- pression at the greater and anterior extremity produced by the retraction of part of the body. I watched attentively and for a long period a number of these animalcules in the hope of seeing the head completely protruded, but with- out success. On compressing the animalcula between plates of glass, a group of long, slen- der, straight, sharp-pointed spines became vi- sible within the body, at its anterior part, and directed towards the anterior depression, pre- cisely resembling the parts described and fi- gured by Ehrenberg as the teeth of the Poly- gastric Infusories ; the rest of the body was occupied by large clear globules, the stomachs ? and smaller granules. Animalcules thus orga- nized, it is evident, cannot be classed with cystic Entozoa, but must be referred to the Polygastric Infusoria, The globular cyst which is commonly deve- loped in the brain of Sheep differs from the Echinococcus in having organically attached to itanumber of small vermiform appendages, pro- vided severally with suctorious orifices, and an uncinated rostellum, similar to those in the head of the Armed Tanis. But as this cystic genus, denominated Canurus, (xonof, communis, av^oc, cauda, from the terminal cyst being common to many bodies and heads,) is not met with in the human subject, a simple notice of it is here sufficient. When the dilated cyst forms the termina- tion of a single Entozoon, organized as above described, it is termed Cysticercus, (xvotk, vesica, xipx.of, cauda), and of this genus there are several species, distinguished for the most part by the forms and proportions of the neck or body intervening between the head and the cyst ; as for example, the Cyst. J'asciolaris, Cyst, fistularis, Cyst, longicoltis, Cyst, tenuicollis, &c. The only species of this genus known to infest the human body is the Cysticercus cellulose, Rud. (the Hydatis Finna of Blumenbach). It is developed, like the Trichina, in the interfascicular cel- lular tissue of the muscles, and, like it, is in- variably surrounded by an adventitious cap- sule of the surrounding substance condensed by the adhesive inflammation. Fig. 59 exhi- Fig. 59. Portion of human muscle, with Cysticercus cdluloscc. EWTOZOA. 119 bits a portion of muscle thus infested; a the adventitious cyst laid open, exposing the Hy- datid; a' the adventitious cyst elongated by the extension of the head and neck of the inclosed hydatid b in the direction of the muscular fibres. The cysticercus itself sometimes attains the size exhibited in Jig. 60, in which a indicates the Fig. 60. Fig. 61. Magnified head of Cysticerus celluloses. head, b the neck or body, and c the dilated vesicular tail. Fig. 61 exhibits the head sufficiently magnified to show the uncinated rostellum or proboscis d for irritation and adhesion, and the suctorious discs e e for im- bibing the surrounding nutriment. The occurrence of this Entozoon in the Hu- man Subject appears to be less common in this country than on the Continent. In the course of five years we have become acquainted with only two cases, one in a subject at the Dis- secting-Rooms of St. Bartholomew's, the other in a subject at the Webb-street School of Ana- tomy. Rudolphi relates that out of two hun- dred and fifty bodies dissected annually at the Anatomical School of Berlin, from four to five were found through nine consecutive years to be infested more or less copiously with the Cysticercus cellulose; for the most part the subjects had been of the leucophlegmatic temperament, but not affected with ascites or anasarca. The muscles most obnoxious to the Entozoon in question are the glutcei, psoas, iliacus internus, and the extensors of the thigh; they have been found also in the muscular tissue of the heart, and in parts not muscular, as the brain and eye. Soemmering detected one specimen of the Cysticercus cellulose in the anterior chamber of the eye of a young woman a;t. 18.* The following is a more re- cent account of a specimen which was deve- loped in the anterior chamber of the eye of a patient in the Glasgow Ophthalmic Infirmary. " Case. — From the month of August, 1832, till about the middle of January, 1833, when she was first brought to Mr. Logan, the child had suffered repeated attacks of inflammation in the left eye. Mr. L. found the cornea so nebulous, and the ophthalmia so severe, that he dreaded a total loss of sight. He treated the case as one of scrofulous ophthalmia; and after the use of alterative medicines, and the appli- cation of a blister behind the ear, the inflam- * See Isis, 1830, p. 717, as quoted by Norc'- mann, Mikrographisrhe Beitrage zur Naturgcschicte tier wirbellosen thiere. matory symptoms subsided, leaving, however, a slight opacity of the lower part of the cornea. After a week, the child was again brought to Mr. L., who, on examining the eye, disco- vered, to his great surprise, a semitransparent body, of about two lines in diameter, floating unattached in the anterior chamber. This body appeared almost perfectly spherical, ex- cept that there proceeded from its lower edge a slender process, of a white colour, with a slightly bulbous extremity, not unlike the pro- boscis of a common fly. This process Mr. L. observed to be of greater specific gravity than the spherical or cystic portion, so that it always turned into the most depending position. He also remarked that it was projected or elongated from time to time, and again retracted, sp as to be completely hid within the cystic portion ; while this, in its turn, assumed various changes of form, explicable only on the supposition of the whole constituting a living hydatid. " On the 3d April, when I examined the case, I found the cornea slightly nebulous, the eye free from inflammation and pain, and the ap- pearances and movements of the animal exactly such as described by Mr. Logan. When the patient kept her head "at rest, as she sat before me, in a moderate light, the animal covered the two lower thirds of the pupil. Watching it carefully, its cystic portion was seen to be- come more or less spherical, and then to assume a flattened form, while its head I saw at one moment thrust suddenly down to the bottom of the anterior chamber, and at the next drawn up so completely as scarcely to be visible. Mr. Meikle turned the child's head gently back, and instantly the hydatid revolved through the aqueous humour, so that the head fell to the upper edge of the cornea, now become the more depending part. On the child again leaning forwards, it settled like a little balloon in its former position, preventing the patient from seeing objects directly before her, or below the level of the eye, but permitting the vision of such as were placed above. Mr. Logan had observed no increase of size in the animal while it was under his inspection. Mr. Meikle had watched it carefully for three weeks without observing any other change than a slight increase in the opacity of the cystic portion. " To every one who had seen or heard of Mr. Logan's case, the question naturally occurred, Ought not this animal to be removed from the eye? Mr. Logan and Mr. Meikle appeared to have deferred employing any means for destroy- ing or removing it ; first, because it seemed to be producing no mischief : and, secondly, be- cause there was a probability that it was a short-lived animal, and likely therefore speedily to perish and shrink away, so as to give no greater irritation than a shred of lenticular capsule. Various means naturally suggested themselves for killing the animal, such as passing electric or galvanic shocks through the eye, rubbing in oil of turpentine round the orbital region, giving this medicine internally in small doses, or putting the child on a course of sulphate of quiua, or some other vegetable 120 ENTOZOA. bitter known to be inimical to the life of the Entozoa. As the patient appeared to be in perfect health, it was natural to suppose that the other organs were free from hydatids, and that a change of diet would have little or no effect upon the solitary individual in the aque- ous humour. Had she, on the contrary, pre- sented a cachectic constitution, with pale com- plexion, tumid belly, debility, and fever, none of which symptoms were present, we should have been led to suspect that what was visible, in the eye was but a sample of innumerable hydatids in the internal parts of the body, and might have recommended a change of diet, with some hopes of success. In the course of six weeks after I saw the patient, the cysticercus having enlarged in size, the vessels of the con- junctiva and sclerotica became turgid, the iris changed in colour, and less free in its motions, while the child complained much of pain in the eye ; it was decided that the operation of ex- traction should be attempted, and I owe to Dr. Robertson of Edinburgh, who operated, the communication of the following particulars. The incision of the cornea was performed with- out the slightest difficulty, but no persuasion or threats could induce the child again to open the eye ; she became perfectly unruly, and the muscles compressed the eye-ball so powerfully that the lens was forced out, and the hydatid ruptured. The patient was put to bed in this state. In the evening Dr. R. succeeded in getting the girl to open the eyelids, when with the forceps he extracted from the lips of the incision the remains of the animal in shreds, it being so delicate as scarcely to bear the slightest touch. A portion of the iris remained in the wound, which nothing would induce the girl to allow Dr. R. to attempt to return. " After the eye healed, the cornea remained clear, except at the cicatrice, where it was only semitransparent; the pupil, in consequence of adhesion to the cicatrice, was elliptical, and the opaque capsule of the lens occupied the pu- pillary aperture. The patient readily recog- nized the presence of light." The Cysticercus cellulosa occurs also in quadrupeds, and is found most commonly and in greatest abundance in the Hog, giving rise to that state of the muscles which is called " measly pork." Of the Cestoid Ol der of Entozoa two species belonging to different genera infest the Hu- man Body. The Swiss and Russians are troubled with the Bo'thriocephdlus latus; the English, Dutch, and Germans with the Tama solium : both kinds occur, but not simulta- neously in the same individual, in the French. It is not in our province to dwell upon the medical remedies for these parasites, but we may observe that the old vermifuge mentioned by Celsus, viz. the bark of the pomegranate, is equally efficacious and safer perhaps than the oleum terebinthina commonly employed in this country for theexpulsion of theTape-worm. From the singular geographical distribution, as it may be termed, of the above Cestoid parasites, the Bothriocepnalui latus rarely falls under the observation of the English Enlozoo- logist. It may be readily distinguished from the Tenia solium by the form of the segments, which are broader than they are long, and by the position of the genital pores, which occur in a series along the middle of one of the flat- tened surfaces of the body, and not at the mar- gin of each segment as in the Tania solium. The head, which was for a long time a deside- ratum in natural history, has at length been dis- covered by Bremser. It is of an elongated form, two-thirds of a line in length, and presents, in- stead of the four round oscula Fig. 62. characteristic of the true Tania, two lateral longitudinal fossae, or bothria, ( a a, Jig. 62, which is a highly-magnified view of the head of the Bothrioce- phalus latus.) The Tania solium (Jig. 63) attains the length of from four to ten feet, and has been ob- served to extend from the pylo- rus to within seven inches of the anus of the human intes- tine.* Its breadth varies from one-fourth of a line at its an- terior part to three or four lines towards the posterior part of the body, which then again diminishes. The head is small, Head of Bothrio- and generally hemispherical, cephalm latus broader than long, and often magnified. as if truncated anteriorly : the Fie 63. Tcenia solium, two-thirds natural sixe. \ * See Robin, in J urnal de Medecinc, torn. xxv. (1766), p. 222. ENTOZOA. 121 four mouths, or oscula, are situated on the anterior surface, ( a, Jig. 63,) and surround the central rostellum, which is very short, termi- nated by a minute apical papilla, and surround- ed by a double circle of small recurved hooks. The segments of the neck, or anterior part of the body, are represented by transverse rugae, the marginal angles of which scarcely project be- yond the lateral line ; the succeeding seg- ments are subquadrate, their length scarcely exceeding their breadth, they then become sen- sibly longer, narrower anteriorly, thicker and broader at the posterior margin, which slightly overlaps the succeeding joint ; the last series of segments are sometimes twice or three times as long as they are broad. The generative orifices (b, b) are placed near the middle of one of the margins of each joint, and are generally alter- nate. The Tania solium is subject to many varieties of form or malformations; the head has been ob- served to present six oscula instead of four. In the Imperial Museum at Vienna, so celebrated for its entozoological collection, there is a por- tion of a Tania solium, of which one of the margins is single and the other double, as it were two taeniae joined by one margin. In the Museum of the College of Surgeons is preserved a fragment of the Tsema solium of unusual size; it swells out suddenly to the breadth of three- fourths of an inch with a proportionate degree of thickness, and then diminishes to the usual breadth.* The species of Tania infesting the intestines of other animals are extremely numerous, ne- vertheless they are rare in Fishes, in which they seem to be replaced by the Bothriocephali and Ligulte. The determination of the species in this, as in every other natural and circumscribed genus, is extremely difficult and often uncer- tain : their study is facilitated by distributing them into the three following sections, of which the first includes those species which are de- prived of a proboscis, Teenia inermes ; the second those which have a proboscis, but un- armed, T&n'ue rostellata ; the third the Tape-worms with an uncinated proboscis, Tania ar- viatcE. The Trematode Order, which is the most extensive division of the Parenchymatous class of En- tozoa, and embraces the greatest number of generic forms, in- cludes only two species infesting the human body, one of which, the liver-fluke (Distoma hepati- cum ), is extremely rare, and the other ( Polystoma Pinguicola) somewhat problematical. The Distoma heputicum (Jig. 64) is found in the gall-bladder and ducts of the liver of a variety of quadrupeds, and very com- monly in the Sheep. When it occurs in the Human species, it is generally developed in the Sec Catal. of Nat. Hist. No. 216. Fig. 64. same locality. The form of this species of En- tozoa is ovate, elongate, flattened ; the anterior pore or true mouth (a) is round and small, the posterior cavity (b), which is imperforate and subservient only to adhesion and locomotion, is large, transversely oval, and situated on the ventral surface of the body in the anterior moiety. Between these cavities there is a third orifice (c) exclusively destined, like the orifice on each joint of the Taenia, to the generative system ; and from which a small cylindrical process, or lemniscus, is generally protruded in the full-sized specimens. The form of the body is so different in the young Distomata, that Rudolphi was induced to believe the specimens from the human gall- bladder which were in this state, to belong to a distinct species, which he termed lanceo- latum ; this modification, which is wholly de- pendent upon age, is shown in the subjoined figure ; and we shall hereafter have to notice the more extraordinary changes, amounting to a metamorphosis, which the Distomata infesting the intestines of Fish undergo. The Polystoma Pinguicola was discovered by Treutler, in the cavity of an indurated adi- pose tubercle, in the left ovarium of a female, aetat. 20 ; it is represented in situ, at A, Jig. 62. Its natural size and shape is shewn at B, the body is depressed,subconvex above, concave below, subtruncate anteriorly, a little contracted behind the head, pointed at the posterior extremity. On the under side of the head C, there are six orbicular pores disposed in a semi- lunar form : a larger sucto- rious cavity occurs on the ventral aspect at the begin- ning of the tail (b B), and a small orifice is situated at the apical extremity. A second species of Po- lystoma (Polystoma Vena- rum ), stated by Treutler to have been situated in the anterior tibial vein of a Man, which was accidentally ruptured while bathing, is generally supposed to have belonged to a species of Planaria, and to have been acci- dentally introduced into the strange locality above-mentioned . The worms of the Trematode order are those which are most frequent in the interior of the eyes of different animals, perhaps the most singular situation in which Entozoa have as yet been found, and respecting which much in- teresting information has recently been given by Ur. Nordmann, in the first part of his beautiful work entitled " Mikrographische Beitrage zur Naturgeschicte der Wirbellosen Thiere." Of the species described and figured in that work, we have selected for illustration the Diplostomum volvens. Fig. 66 exhibits a magnified view of the vitreous humour of a Perch ( Percujluviutilis, Linn.) containing numerous specimens of fchis Polystoma Pinguicola. 122 ENTOZOA. Fig. 66. Diplostomum volvens in the eye of a Perch. parasite, which sometimes exists in such pro- digious numbers, that the cavity of the eyeball is almost exclusively filled by them. They not only infest the vitreous but also the aqueous humours, and have been found in the choroid gland. All the species of Diplostomum are very small, seldom exceeding a sixth part of a line in length. They resemble the genus Distoma, and present some affinity to the Cercaria, which infest the fresh-water Snails ; but they have characters peculiar to themselves which entitle them to rank as a distinct genus ; of these the principal external one is the addi- tional sucker developed on the ventral aspect of the body, as compared with Distoma, whence Nordmann calls the genus Diplosto- mum, though Diplo-cott/lus would be the more appropriate designation, since, as before ob- served, the ventral depressions are simply organs of adhesion, and have no communication with the alimentary canal. Besides the suckers the Diplostomum has an anterior mouth f a, jig. 81), as in the Distoma. The first or anterior sucker (b,Jig. 81 ) is twice the size of the mouth; and the second ( c,jig. 81) is again double the size of the former. As the figure shows the vessels from the dorsal aspect, these suckers can only be seen in outline. The animal has great power over them and can contract the parenchyma of the body surrounding them, so as to make them project like rudimental extremities from the ventral surface. It has been already observed that no species of the Acanthocephalous order of Entozoa has hitherto been found in the Human body, the illustration of this form of the Sterelmintha will therefore be confined to the section treat- ing of the general anatomy of the Entozoa. The Class Calelmintha contains several species of Entozoa which are obnoxious to man ; of these may be first mentioned the Medina or Guinea-worm ( Filaria Medinensis, Gmel.) This species is developed in the sub- cutaneous cellular texture, generally in the lower extremities, especially the feet, sometimes in the scrotum, and also, but very rarely, be- Fig. 67. neath the tunica conjunctiva of the eye. It appears to be endemic in the tropical regions of Asia and Africa. The length of this worm varies from six inches, to two, eight, or twelve feet; its thick- ness from half to two-thirds of a line ; it is of a whitish colour in general, but some- times of a dark brown hue. The body is round and sub- equal, a little attenuated to- wards the anterior extremity. In a recent specimen of small size, we have observed that the orbicular mouth was surround- ed by three slightly raised swellings, which were conti- nued a little way along the body and gradually lost ; the body is traversed by two lon- gitudinal lines corresponding to the intervals of the two well- marked fasciculi of longitu- dinal muscular fibres. The caudal extremity of the male is obtuse, and emits a single spiculum ; in the female it is acute and suddenly inflected. The Filaria Medinensis, as has just been observed, is oc- casionally located in the close vicinity of the organ of vision ; but another much smaller spe- cies of the same Genus of Nematoidea infests the cavity of the eyeball itself. The Filaria oculi humani was detected by Nordmann in the Liquor Morgagni of the capsule of a crystalline lens of a man who had undergone the operation of extraction for ca- taract under the hands of the Baron von Grafe. In this in- stance the capsule of the lens had been extracted entire, and upon a careful examination half an hour after extraction there wereobserved in the fluid above-mentioned two minute and delicate Filaria coiled up in the form of a ring. One of these worms, when examined microscopically, presented a rupture in the mid- dle of its body, probably occasioned by the ex- tracting needle, from which rupture the intesti- nal canal was protruding ; the other was entire and measured three-fourths of a line in length ; it presented a simple mouth without any appa- rent papillse, (as are observed to characterize the large Filaria which infests the eye of the Horse,) and through the transparent integument could be seen a straight intestinal canal, sur- rounded by convolutions of the oviducts, and terminating at an incurved anal extremity. The third species of Filaria enumerated among the Entozoa Hominis is the Filaria Filaria Medinensis. ENTOZOA. 123 bronchialis (jig. 68); it was detected by Treut- ler* in the enlarged Fig. 68. bronchial glands of a n man: the length of this JST. worm is about an inch ; l/f it is slender, subatten- 11 uated anteriorly (a), II and emitting the male j j spiculum from an in- II curved obtuse anal ex- \\ tremity (6). w. The next Human \% Entozoon of the Ne- matoid order belongs \|i to the genus Tricho- ]l cephalus, which, like J a Filaria, is character- li ized by an orbicular M mouth, but differs from it in the capillary form ^ of the anterior part of Filaria bronchialis, »he h°p> anf in. the magnified. i°rm of the sheath or preputial covering of the male spiculum. The species in question, the Tricocephalus dispar, Rud. is of small size, and the male (* fig. 69) is rather less than the female. It occurs most commonly in the coecum and colon, more rarely in the small intestines. Occasionally it is found loose in the abdominal cavity, having perforated the coats of the intestine. The capillary portion of this species makes about two-thirds of its entire length ; it is transversely striated, and contains a simple straight intestinal canal; the head (a) is acute, with a small simple terminal mouth. The thick part of the body is spirally convoluted on the same plane, and exhibits more plainly the dilated moniliform intestine (6) ; it terminates in an obtuse anal extremity, from the inner side of which pro- ject the intromittent spiculum and its sheath (c, d). The corresponding extremity in the female exhibits a simple foramen, which, like the outlet of a cloaca, serves the office of both anus and vulva. With respect to the following parasite of the Human body, the Spiroptera Hominis, Rud., considerable obscurity prevails. A poor wo- man, who is still living in the workhouse of the parish of St. Sepulchre, London, has been subject, since the year 1806, (when she was twenty-four years old,) up to the present time, to retention of urine, accompanied with dis- tress and pain indicative of disease of the bladder. The catheter has been employed from time to time during this long period to draw off the urine, and its application has been, and continues occasionally to be, followed by the extraction and subsequent discharge of worms, or vermiform substances, with nume- rous small granular bodies. The latter are of uniform size, resembling small grains of sand : those which we have examined, and which were preserved in spirit, present a subglobular, or irregularly flattened form ; but when recently * Opusc. Patholog. Anat. p. 10, tab. ii. fig. 3 — 7. Hamularia Lymphaiica. Fig 69. Trichocepludus dispar. (*Natural she. ) expelled, I am assured by my friend Dr. Arthur Farre, that they are perfectly spherical ; they consist of an external smooth, firm, dia- phanous coat, including a compact mass of brown and minutely granular substance. The inner surface of the containing capsule pre- sents, under the microscope, a regular, beau- tiful, and minute reticulation, produced by depressions or cells of a hexagonal form. These, therefore, we regard as ova, and not as fortuitous morbid productions.* The vermi- * " Ovula vero sic dicta subglobosa cum arenulis 124 ENTOZOA. form substances are elongated bodies of a moderately firm, solid, homogeneous texture, varying in length from four to eight inches ; attenuated at both extremities; having the diameter of a line half-way between the ex- tremities and the middle part, where the body is contracted and abruptly bent upon itself. Some are irregularly trigonal, others tetragonal. In the three-sided specimens one surface is broad, convex, and smooth ; the other two are narrow and concave, and separated by a nar- row longitudinal groove, in which is sometimes lodged a filamentary brown concretion. In the tetragonal portions the broad smooth sur- face is divided into two parts by the rising of the middle part of the convexity into an angle. The most remarkable appearance in these am- biguous productions is the beautiful crenation of one of the angles or ridges between the convex and concave facet; which, from its regularity and constancy, can hardly be ac- counted for on the theory of their nature and origin suggested by Rudolphi : ' lymphamque in canalibus fistulosis coactam passimque com- pressam filum inrequale efformare crediderim.'* On the other hand it is equally difficult to form any satisfactory notion of these substances as organized bodies growing by an inherent and independent vitality. We have not been able to observe a single example in vhich the substance had both extremities well defined and unbroken ; these, on the contrary, are flattened, membranous, and more or less jagged and irregular. They present no trace of ali- mentary or generative orifices on any part of their exterior surface, nor any canals subser- vient to those functions, in the interior paren- Fig. 70. Spiroptera hominis. (* Natural sixe.) per catheterem ex vesica pauperculs educta, ne- quaquam talia habenda sunt. Corpuscula sunt plus minus globosa, tertiam lineae partem diametro superantia, duriuscula, forcipi comprimenti reni- tentia, dissecta solida visa, quominus pro hydalulis haberi possint, quales pritno suspicatus sum. Con- crcmenta; sunt lymphatica in vesica imorbosa ex humoribus alienatis ibidem secretis, simili forsan inodo acarenula; ex lolio pra;cipitata." — Rudolphi, Synops. Entoz. p. 251. * Ibid. p. 252. chyma. If subsequent observations on re- cently expelled specimens of these most curious and interesting productions should, however, establish their claims to be regarded as Entozoa, they will probably rank as a sim- ple form of Sterelmint/ia.* The existence of the Spiroptera Hominis is founded on the observation of substances very different from the preceding productions. The specimens so called were transmitted to Ru- dolphi, in a separate phial, at the same time with the ova and larger parenchymatous bodies above described, and are presumed to have been expelled from the same female under the same circumstances. They consisted of six small Nematoid worms of different sexes ; the males (fig. 70*) were eight, the females ten lines in length, slender, white, highly elastic. The head (£ mese m°tions. The Tcenia solium, l'Ei I when recently expelled from the Ttenia body by the irritation of a vermifuge solium. remedy, is occasionally contracted to the length of a few inches, the * See Preparation, No. 409 A, Physiological Series Mus. Roy. Coll. of Surg. Catalogue, vol. i, p. 115. f Rudolphi, Hist. Entoz. i. p. 223. segments appearing as close-set transverse stria; ; when placed in water, after a few hours it will have returned to a length of as many feet. Werner* relates an instance of a Taenia which extended from the anus of a patient to the length of three feet, and which returned itself almost wholly into the intestine, the dependent part being drawn upwards by the superior. Other and still more extraordinary instances of the movements of the Cestoid worms are on re- cord ; but that the separated joints of the Tania solium should be able to creep several feet up a perpendicular wall could scarcely gain a mo- ment's credit, if the fact were not related by no less distinguished a naturalist than Pallas.t In general the muscular fibres cannot be observed in the diaphanous bodies of the smaller Trernatoda, yet every part is endowed with active contractility: in the larger species, however, both longitudinal and transverse strata of fibres may be demonstrated in the tegumen- tary muscular covering of the body ; both which we have distinctly seen in the large Distoma clavatum. The muscular fibres of the aceta- bula are disposed in two series, one radiating from the centre to the circumference, the other in concentric circles. The muscular tissue is also well developed around the base of the sucker, by which the animal is enabled to pro- trude them from the surface. In the Planaria, in which, as in the Tania, according to our observations, the muscular system is indicated only by striae on the super- ficies of the apparently homogeneous paren- chyma, the phenomena of muscularity are strikingly displayed in the varied and energetic actions of the living animal. They lengthen, shorten, widen, contract, or contort the body in various degrees and directions : their mode of locomotion on a solid plane is by an insen- sible undulation, or successive approximation of small proportions of the body, producing a gliding movement, as in the Slug; and the same actions take place in swimming through the water, except that the body is reversed ; and the ventral surface turned upwards, as in the Carinaria and other aquatic Gastropods. When seizing a living prey, as in fig. 76, the contractions of the body Fig. 76. are more vigorous and In the Fkhinorhynchus the muscular fibres are of a whitish colour, semi- transparent, and of a ge- latinous appearance; they Planaria lactea (B), aie eminently contractile, feeding on a Nais. and readily respond to the application of both chemical and pbysical stimuli. Cloquet ob- served them to contract under the influence of the galvanic current six hours after the cessation * As quoted by Rudolphi. * Taenia ad trium ulnarum longitudinem ex mulieris ano propen- dens, in casu qnem Wernerus (1. c. 47) ret'ert, tota fere in pristinum hospitium rediit, pars pro- pendens itaque a superiore sursum ducta : similes omnino casus Andryus habet.' — Ibid. p. 223. t Also quoted by Rudolphi, p. 223. ENTOZOA. 129 of all spontaneous movement. The general muscles of the body are disposed in two layers, of which the fibres of the external are trans- verse, those of the internal longitudinal. With respect to the disposition of the mus- cular system of the Nematoid worms, a dif- ference of opinion is entertained by some ex- perienced comparative anatomists. Professor De Blainville* describes, in the Ascaris lumbricoides, the external stratum of muscular fibres as being longitudinal, while the internal, he observes, are evidently trans- verse, and much more numerous at the an- terior than the posterior part of the body. M. Cloquet, on the contrary, in his elaborate monograph on the Ascaris lumbricoides, states that the exterior layers of muscular fibres are transverse, and the internal longitudinal. In a large specimen of the Strongylus gigus, Rud., which we have dissected and examined micro- scopically for the muscular system, we find that a very thin layer of transverse fibres ad- heres strongly to the integument, the fibres being imbedded in delicate furrows on the internal surface of the skin ; within this layer, and adhering to it, but less firmly than the transverse fibres do to the integument, there is a thicker layer of longitudinal fasciculi, which are a little separated from one another, and distributed, not in eight distinct series, but pretty equally over the whole internal circumference of the body. Each fasciculus is seen under a high magnifying power to be composed of many very fine fibres, but these do not present the transverse striae which are visible by the same power in the voluntary muscular fibres of the higher animals. The longitudinal fibres are covered with a soft tissue composed of small obtuse processes, filled with a pulpy substance, and containing innumerable pellucid globules, and at the an- terior extremity of the body this tissue assumes a disposition as of transverse fasciculi ( fig. 79). In the Ascaris lumbricoides similar internal transverse bands are shown in Jig. 88,e,e, and are those which Professor Blainville regards as muscular, and Cloquet as vascular organs. We cannot detect a tubular structure in these parts, neither have they the texture and con- sistence of the true fibrous parts : they are soft pulpy substances, doubtless connected with the nutritious functions, and probably the or- gans of absorption. Besides the general muscular investment of the body, there are distinct muscles in most of the Entozoa, developed for the movement of particular parts, as the retractile hooks of the Linguatula and Porocephalus, and the probo- scides of the Cestoid and Acanthocephalous worms. Of the latter organ the Lchinorhynchus gigas offers a good example. The proboscis in this species (Jig. 77) is a short, firm, elastic, cylindrical tube, buried with its appropriate mus- cles in the neck of the animal, as in a sheath; and having its anterior extremity (a, b) terminated * Dictionnaire des Sciences Naturelles, torn. iii. App. p. 40. + Anatomie de l'Ascaride Lombricoide, p. 17. VOL. II. Fig. 77. Retracted proboscis and its muscles, Echynorhynchus gigas. Cloquet. by a spherical eminence armed with four rows of recurved spines. The retractor muscles are four in number, two superior and two inferior, (J\ g,) flattened, elongated, and of a triangular figure. They are continuous at their base or posterior extremity, with the longitudinal fibres of the body ; their anterior extremity, which is extremely delicate, is inserted into the poste- rior part of the proboscis. The protractile mus- cles (c, d) are also four in number, short but strong, and forming, as it were, a sheath to the proboscis ; they are attached to the anterior part of the tegumentary sheath, and pass back- wards to be inserted into the posterior extremity of the proboscis in the intervals left by the retractor muscles. The motions of the pro- boscis thus liberally supplied, are, as might be expected, more lively than those exhibited by any other part of the body. When it is drawn back into its sheath by means of the retractor muscles, the hooklets seem to be drawn close to the side of the bulbous extremity, whence we may infer that these also have their appro- priate muscles. Nervous system. — The Entozoa in which the nerves can be most easily and distinctly demonstrated, are the Linguatula tanioides and the larger species of the Nematoidea, especially the Strongylus gigas. In the Linguatula a proportionally large ganglion (g, Jig. 78) is situated immediately behind the mouth, and below the oesophagus, which is turned forward in the figure, at o; small nerves (h, i, k) radiate from this centre to supply the muscular apparatus of the mouth and contiguous prehensile hooklets ; and two large chords (7, 1) pass backwards and extend along the sides of the abdominal aspect of the body to near the posterior extremity, where K 130 ENTOZOA. E'4 78. ihey gradually become - expanded and blended ;* with the muscular tissue. I® _ In the Strongylus gigas, a slender nervous ring (a, a, Jig. 79) sur- rounds the beginning of the gullet, and a single chord is continued from its inferior part and ex- tends in a straight line along the middle of the ventral aspect (c, d) to the opposite extremity of the body, where a slight swelling is formed im- mediately anterior to the anus, which is surround- ed by a loop (e) analo- gous to that with which the nervous chord com- menced. The abdominal nerve is situated internal to the longitudinal mus- cular fibres, and is easily distinguishablefromthem with the naked eye by its whiter colour, and the slender branches (b, b) which it sends off on each side. These transverse twigs are given off at pretty regular intervals of about half a line, and may be traced round to nearly the opposite side of the body. The entire nervous chord in the fe- male of thisspecies passes to the left side of the vulva, and does not di- vide to give passage to the termination of the vagina, as Cloquet de- scribes the corresponding ventral chord to do in the Ascaris Lutnbricoides. In the latter species, and most other Nematoidea, a dorsal nervous chord is continued from the oesophageal ring down the middle line of that aspect of the body corres- ponding to the ventral chord on the opposite aspect; but we have not found the dorsal chord in the Strongylus gigas. The nervous system in the latter Entozoon obviously therefore ap- proximates to that of the Anellides; but it differs in the absence of the ganglions, which in all the red-blooded worms unite at regular inter- vals two lateral nervous columns ; it resembles on the other hand most closely the simple and single ventral chord in the Sipunculus. Living Ascarides are sensible to different mechanical stimuli applied to the surface of the body, and the sudden and convulsive movements which take place when alcohol, vinegar, or alum-solution are applied to the mouth, would seem to imply that they possess a sense of taste: tor light, noise, or odour they 111 Nervous system and fe- male organs of genera- tion of Linguatula tce- nioides, magnified. mm mm Commencement and termina- tion of the nervous system, Strongylus gigas, magnified. Fig. 79. are, as might be ex- pected from the sphere of their ex- istence, totally in- sensible. In those Entozoa which infest the parts of an animal body, where they may be exposed to the influ- ence of light, as the gills of fishes, we should not be un- prepared to meet with coloured eye- specks, or such sim- ple forms of the or- gan of vision as oc- cur in Infusoria and other invertebrate animals of a low grade of organiza- tion. Nordmann de- tected four small round ocelli, of a dark-brown colour, in the Gyrodactylusauriculatus, a Cestoid worm, found in the branchial mucus of the Bream and Carp ; the eye-specks are situated a little way behind the head, and yield on pressure a blackish pigment. V. Baer observed two small blackish ocelli behind the orifice of the mouth in the Polystomum Integerrimum, a Trematode species, which infests the urinary or allantoid bladder of the Frog and Toad. Now this large receptacle is well known to contain almost pure water ; and as the Poly- stomum is very closely allied to the Planaria, which habitually live in fresh water, it is pro- bable that the allantoid bladder may be only its occasional and accidental habitation. With respect to the Planaria these are almost univer- sally provided with eye-specks, varying in num- ber from two, as in the Planar ia lactea, (Jig. 80, A) to forty, of a brown or black colour, the external covering of which is tran- sparent and corneous. From the experiments of M. Duges* on these non-parasitic Stere.lminthu, we learn that when the solar light is directed to the head, they escape from its influence by a sudden move- ment, and they also give unequi- vocal, though less energetic, proofs of their subjection to the influence of diffused and artificial light. The temporary ocelli observed in the young of certain species of Dis- toma\ will be presently noticed. * Annales des Sciences Natnrelles, 1828, p. 10. t Conf. also Rudolphi, Synops. Entoz. p. 442, where, in the description of the Scolex polymor- phus, a Cestoid worm infesting the intestines of Fish and Cephalopoda, he observes, " punctu duo volo corporis albi sanguinea, sa?pe lulgentia, qualia nullis in Entozois aliis videre Iicuit, quaeque in Gobii minuti Scolece vasa duo rubra parallela pone caput incipientia et retrorsum ducta, in corpore autera evanida, effingere observavi." ENTOZOA. 131 Digestive organs. — We have already alluded to the two leading modifications of the ali- mentary canal, on which the binary division of the Entozoa of Rudolphi is founded, viz. into Sterelmintha or those in which the nu- trient tubes, without anal outlet, are simply excavated in the general parenchyma, and into the Cazlelmintha, in which an intestinal canal, with proper parietes, floats in a distinct ab- dominal cavity, and has a separate outlet for the excrements. In both these divisions the mouth is variously modified, so as to afford zoological characters for the subordinate groups ; and the alimentary canal itself in the Sterelmintha presents several important differences of structure. Cystica. — The Cystic worms are generally gifted, as in the species ( Cysticercivs cellulose ) which occasionally infests the human subject, with an uncinated proboscis for adhering to and irritating, and four suctorious mouths for ab- sorbing the fluid secreted by, the adventitious cyst in which they are lodged. In the larger Cysticerci lateral canals may be traced from the suctorious pores extending down the body towards the terminal cyst, but they appear not to terminate in that cavity, the fluid of which is more probably the result of secretion or endosmosis. We cannot, however, partici- pate in the opinion of Rudolphi,* that the retracted head derives nutriment from the surrounding fluid of the caudal vesicle, for if that were the case, where would be the neces- sity for an armed rostellum in addition to the absorbent pores? The frequency with which the Cysticerci are found with the head so retracted, may be attributed to the in- stinctive action arising from the stimulus of diminished temperature and other changes in the surrounding parts occasioned by the death of the animal in which the hydatid has been developed. Cestoidea. — In the Ccstoidea the digestive apparatus commences for the most part by two or four oral apertures, to which, in many spe- cies (the Tania armata ), a central uncinated proboscis is superadded, as in the Cysticerci. Sometimes the mouths are in the form of oblong pits or fossa?, as in the Botliriocephalus lotus, and the allied species grouped under the same gene- ric name; or they have the structure of circular suctorious discs, as in the Tania solium, and othertrue Tania.f In both genera two alimen- tary canals are continued backwards in a straight line near the lateral margins of the body (e, e, . " Osculis lamen canalihusque dictis omnem aquae vim vesica caudali collectam parari potuisse vix credibile, sed hac parata vermem eandem absorbere ideoque semper fere caput liuic immissum offerre, longe aliam vero fluidi advehendi viam dari, plurima suadent."— Hist. Entoz. i. p. 279. t Many beautiful preparations, showing the nutrient canals of the Tania solium injected with coloured size and quicksilver, are preserved in the Hunterian collection, (see Nos. 843, 844, 845.) These were prepared, during the life-time of John Hunter, and were presented to that great anato- mist by Sir Anthony Carlisle, by whom they are described in the ' Observations upon the Struc- ture and (Economy of Taeniae,' in the second vo- lume of the Linnscan Transactions, (1794). Jig. 90), and are united by transverse canals (fi.fi Jig-W) passing across the posterior margins of the segments. These connecting canals are relatively wider in the Tania solium than in the Bothriocephalus latus, their size apparently depending on the length of the segments, which is much greater in the former than the latter. Neither the transverse nor the longi- tudinal vessels undergo any partial dilatations. The chief point at issue respecting the digestive organs of the Tape-worms is, whether the nu- triment is imbibed by them through the pores which occur at the sides or margins of each joint, or whether the entire body is dependent for its nutriment upon the anterior mouths from which the lateral canals commence. The re- sults of numerous examinations, which I have made with this view, both on Bothriocephali* and Taeniae, have uniformly corresponded with those of Rudolphi, and I entirely subscribe to the opinion of that experienced helminthologist, that the marginal or lateral orifices of the seg- ments are exclusively the outlets of the gene- rative organs. In some species of Tape-worm, as the Tania sphanocephalus, in which no ovaria have been detected, there has been a corresponding ab- sence both of lateral and marginal pores, while the lateral longitudinal canals have been pre- sent and of the ordinary size. In the Tania solium the generative pores being placed at one or other of the lateral margins of the seg- ments, the ducts of the ovary and testis ( g, h, Jig. 90) cross the longitudinal canal of that side, and give rise to a deceptive appearance, as if a short tube were continued from the alimentary canal to the pore. But in the Bothriocephalus latus and Bothriocephalus Pythonis the generative pores open upon the middle of one of the surfaces of each segment, and in these it is plain that the lateral nu- trient vessels have no communication with the central pores. The orifices of the segments, in short, correspond with the modifications of the generative apparatus, while the nutrient canals undergo no corresponding change. Nutrition may be assisted by superficial ab- sorption ; and, as Rudolphi suggests,! the se- parated segments may for a short time imbibe nutriment by the open orifices of the broken canals ; but setting aside cutaneous absorption and the more problematical action of the rup- * Principally on that species which infests the intestines of the large serpent commonly exhibited in this country the Python Tigris, Dand. And we invite the attention of comparative anatomists interested in this point to an injected preparation of one of these worms in the Museum of the Royal College of Surgeons, No. 846 A. t " Al. Olfers (de veget. et anim. p. 35) articulos TamicB singulos ope absorptionis cutanea? perparum, maxime autem ope osculi marginalis nutriri contendit, sed osculum hoc vere ad genitalia pertinpre in capite insequente evincam. Si cl. vir absorptionem cutaneam minoris sestumat, hac de re non litigabo, sed res alio modo explicari potest. Annon enim ad vasa linearia nutneniia, utrinque longitudinaliter decurrentia, si articulus solutus est, in utroque ejus fine utrinque hiantia, absorbendi ofncium deferri posset." — Synops. Entoz. p. 585. K 2 132 ENTOZOA. tured vessels, the head of the Tape-worm is the sole natural instrument by which it im- bibes its nutriment, and it is to the expulsion of this part that the attention of the physician should be principally directed, in his attempts to relieve a patient from these exhausting para- sites. Trematoda. — Four kinds of vessels or canals are met with in the parenchymatous body of the Trematode worms, viz. digestive, nutritive or sanguiferous, seminal, and ovigerous. In the genus Monostoma, the digestive canal is bifur- cated, each branch traverses in a serpentine direction the sides of the body, and they are united, in some species, by a transverse com- municating vessel at the caudal extremity ; in others, as Monost. mutabile, they converge and terminate in an arched vessel at the posterior part of the body. They are of small size, and not very clearly distinguishable from the sangui- ferous vessels. In the Distoma hepaticum, the digestive organs are more distinctly developed. The oesophagus is continued from the anterior pore, and forms a short wide tube, shaped like an inverted funnel. Two intestinal canals are continued from its apex, which immediately begin to send off from their outer sides short and wide ccecal processes, and continue thus ramifying to the opposite end of the body, but have no anal outlet. Rudolphi* states that when successfully injected with mercury, more minute vessels are continued from the apices of the digestive canals, which form a net- work over the superficies of the body. A similar dendritic form of the digestive canal obtains in the singular genus Diplozoon, discovered by Nordmann in the gills of the Bream; the central canal and ramified ccecal processes in this En- tozoon are represented (Jig. 328, vol.i. p. 654,) on that moiety, which is opposite the left hand of the observer : on the other moiety the vascu- lar system alone is delineated. The latter is not, like the digestive canal, common to both halves of the body, but consists of two closed systems of vessels, each peculiar to its own moiety. Two principal trunks, a, a, traverse the sides of each moiety, preserving a uniform diameter throughout their entire course. In the external vessels marked a, a, Nordmann states that the blood is conveyed forwards or towards the head: in the internal ones, it passes back- wards in the opposite direction. The latter vessels commence by many minute branches which unite in the space between the oral suckers and the anterior extremity of the body, and terminate between the disc and suckers at the posterior extremity of the body. The exterior or ascending vessels begin where these disappear and pass towards the opposite end of the body : both trunks freely inter- communicate by means of superficial capil- laries. The blood moves through them with great rapidity, but without being influenced by any contraction or dilatation of the vessels themselves. The circulation continues for three or four hours to go on uninterruptedly in * Entoz, Synopsis, p. 583. each moiety of the Diplozoon, after they have been separated from one another by a division of the connecting band. The blood itself is per- fectly limpid. It should be observed, with refe- rence to the above description, that the appear- ance of circulatory movements in the vessels of the Diplozoon par adoxum is ascribed by Ehren- berg ( Weigmann's Arckiven, 1835, th. ii.) and Siebold (Ibid. 1836, th. ii.) to the motion of cilia on the inner surface of the vascular canals. In the genus Diplostomum, in which the nutritious and vascular systems characteristic of the Trematoda are peculiarly well displayed, (fig. 81,) a short and slightly dilated canal is continued from the mouth, and soon divides into two alimentary passages or intestines, e, e, which diverge, and proceed in a slightly un- dulating course, towards the hinder sacciform appendage of the body, dilating as they de- scend, and ultimately terminating each in a blind extremity, f,f. The contents of this long bifid blind alimentary canal are of a yellowish brown colour, especially in old individuals, and consist of a finely granular substance. As there is no separate anal aperture, the crude and effete particles are probably regurgitated and cast out by the mouth, as in all other Trematoda. The posterior projection of the body, g, Nordmann compares to the posterior appen- dage in the Cercaria ; it is terminated by a posterior aperture which seems to be the ex- cretory outlet of some secerning organ ; since a milky fluid is sometimes ejected from it with force. In a species of Distoma ( Distoma clavatum, Rud.) which I recently dissected, Fig. 81. ENTOZOA. 133 there is a similar aperture which forms the outlet of a vertically compressed sac situ- ated between the chyle-receptacles (see Trans- actions of the Zoological Society, plate 4, p. 381, pi. 41, figs. 17, 18, d, g). In the Diplostomum volvens Nordmann supposes the aperture in question, h, to be the termination of a canal continued from the oviduct. Besides this canal the posterior appendage of the body is occupied by a sac of a corresponding form containing a milky fluid, i, i, and to which the term of chyle-receptacle is given by Nord- mann, as was previously done by Laurer to a corresponding cavity in the Amphisioma coni- cum. The nutritious contents of this canal would seem to exude through the parietes of the coecal extremities of the intestines, as no distinct aperture of communication is obvious. Two vessels, k, k, are continued on each side from the anterior and external part of the chyle receptacle; they extend forwards to the anterior third of the body, and are there broughtinto com- munication by a transverse vessel, which ex- tends across the dorsal aspect of the body. From the point of union of the transverse with the external lateral vessels, a vessel is continued for- ward on each side, appearing as the continuation of the external lateral one. These vessels, m, m, are reflected inward at the anterior angles of the body, and unite in the middle line to form the vessel, n, which may be regarded, according to Nordmann, as representing the arterial trunk, and which is continued to the posterior extremity of the body, distributing branches on each side throughout its whole length. Nord- mann observed a circulation of fluid in the vessels marked m, m, which was unaccom- panied by any pulsation, and which may there- fore be compared to the Fig. 82. cyclosisofthe nutrient fluids in the vessels of Polygas- trica, Polypi, and other Acrita, and is probably due to the action of vibratile cilia. In a few species of Pla- naria the mouth is terminal and anterior, as in the Distornata ; these form the subgenus Prostoma of Professor Duges.* In the greater nu mber of these non- parasitic Sterelmintha the alimentarycanal commences from a cavity situated at the middle of the inferior sur- face of the body. A pro- boscis or suctorious tube (a, fig. 82), varying in length according to the species, is contained in this cavity, from which it can be pro- truded, and the mouth is situated in the form of a round pore at the extremity of this proboscis. The ac- tion of this tube is well dis- Dendritic digestive cavity, Planaria lactea. Duges, Annales des Sciences, 1828, p. 16. played when a hungry Planaria makes an attack upon a Nats ; it then wraps its flat body around its prey (see fig. 76,) and applies to it the extre- mity of its trumpet-shaped sucker ; the red- blood of the little Anellide is seen to dis- appear from the part in contact with the sucker; and if the body of the Nais be broken in the conflict, the Planaria directs the extremity of the proboscis to the torn and bleeding surface. After a meal of this kind the digestive canals of the Planaria are displayed by the red colour of their contents, like the corresponding parts of the Liver-fluke when filled with bile, and they greatly resemble the latter in structure ; instead of two canals, however, three are con- tinued from the base of the proboscis ; one of these is central (6), and passes upwards to the anterior extremity of the body, distributing its vvide coeca on either side ; the other two (c, c) descend, almost parallel to one another, and give off their ccecal processes chiefly from the outer margin, as in the Distoma. The Plunarice are, equally with the parasitic Trematoda, de- void of an anus : and the remains of Poly- gastric infusories swallowed by them have been seen to be regurgitated by the proboscis. Mi- nute nutrient vessels are continued from the extremities of the intestinal cceca, and form a very fine cutaneous network, which communi- cate with a mesial and dorsal canal and two lateral vessels, as in the Diplostomum. Some species of the Trematode Entozoa are infested by parasitic Polygastnca which belong to the Monads : Nordmann observed some brown corpuscles by the sides of the alimen- tary canal of a Diplostdnium, which contained minute particles in continual and lively motion. On crushing the corpuscles between plates of glass an immense concourse of the moving atoms escaped : they were smaller than the Monas atomos of Miiller, of an oval form, and of a clear yellow colour; their movements were very singular : they whirled rapidly round on their axis, then darted forward in a straight line, whirled round again, and again darted forward. When we consider that the Diplos- tomum itself does not exceed a quarter of a line in length, and that the aqueous humour of a single eye serves as the sphere of existence to hundreds of individuals, what views does the fact of the parasites of so minute an Ento- zoon open of the boundless and inexhaustible field of the animal creation ! Acanthocephala.—The worms of this order, although in external form, in the development of the tegumentary and muscular system, and above all in their dioecious generation, they ap- proach very closely the Nematoid Worms, yet preserve the distinguishing character of the Sterelminthoid class in the structure of the digestive organs. In the Echinorhynclius gigas the mouth is an extremely minute pore, situated on a projectile armed proboscis, the structure of which we have already described. From its posterior part are continued two long cylindrical canals (e, e, Jigs. 83,84) which ad- here closely to the muscular fibres by their outer side, and project on the opposite side into the triangular cavity (/i, fig. 84) left between the 134 ENTOZOA. fill ovaries in the female and testes in the male. They are extremely minute at their commencement, but increase so as to be readily visible in the middle of their course. They are trans- parent and irregularly dila- ted or sacculated at inter- vals. Posteriorly they ter- minate in a cul-de-sac, and have no anal outlet. They contain a transparent in- odorous albuminous liquid, give off no visible lateral branches, and do not com- municate together in any part of their course. Be- sides these canals we find in the cavity of the body of an Echinorhynchus two long wavy tubes called lemnisci, (d, d, Jig. 83). They are attached to the lateral parts of the neck by an extremely attenuated an- terior extremity, float freely in the remainder of their extent, and terminate in an enlarged obtuse and imper- forate extremity. They are of a whitish colour, tran- sparent in the living worm, but become opake after death; they present consi- derable variety of form, and would seem to be highly irritable parts, since they are not unfrequently found fold- ed into a packet, or twisted both together, and turned to one side of the body. When examined with a high microscopic power, a tran- sparent vessel is perceived running through the centre and ramifying as it descends in the substance of the lem- niscus, which is soft, fragile, and granular. Cloquet com- pares these organs to the nutrient processes which project into the abdominal cavity of the Ascaris, and they are also regarded by Goeze, Zeder,and Rudolphi as belonging to the organs of nutrition. In the Cazlelmintha or Cavitary Entozoa, the ali- mentary canal is single and of large size, and extends nearly in a straight line from the mouth to the anus, which are at opposite extremities of the body. With regard to the existence of an anal outlet, the parasitic Entozoon, ( Syngamus irachealis, Siebold,) which infests the windpipe of our common Gallinaceous Birds, presents an exception. It was supposed by Montague to be a singleindividual with two pedunculate mouths: Digestive and gene- rative organs, Echi- norhynchus gigas, female. Transverse section of Echinorhynchus gigas. and by Rudolphi was placed in the same group as Distoma furcatum, which is a true double- necked Trematode worm. But the digestive system has the essential character of the ccelel- minthic structure, the intestine floating freely in an abdominal cavity. The orifice at the extremity of the smaller or male branch leads to a muscular oesophagus, which is continuous with a somewhat broader reddish-brown intes- tine, continued in a tortuous manner down the neck, and terminating in a cul-de-sac prior to the confluence of the extremity of this branch with the body of the female. The mouth of the larger branch, which is the true continua- tion of the larger and single body, leads first to a horny basin-like cavity, which communi- cates by an opposite pore, surrounded by six horny hooks or teeth, with the oesophagus, from which a similar reddish-brown intestine is continued, but in a more tortuous manner than in the male, through the whole body, ter- minating in a cul-de-sac at the caudal extre- mity. In both intestinal canals are molecules of apparently the colouring matter of blood. Their inner surface is reticulate. In the freedom of these intestines from the muscular parietes of the body, and in the cy- lindrical form of the latter, we have a close affinity to the Nematoid type: but the intestine is blind — without an anal outlet. It is not, however, bifurcate, as in the true Trematoda. In the genus Linguatula or Pentastonia of Rudolphi, the intestine is a simple straight tube, and is surrounded by the convolutions of the oviduct : the two intest inula cceca with which Rudolphi describes the alimentary canal as being complicated,* appertain to the gene- rative system, and communicate exclusively with the oviduct : the intestine terminates by a distinct anus at the posterior extremity of the body. In the Nematoidea the intestine is also frequently concealed in a part of its extent by the coils of the genital tubes, but these are disposed in masses by the side of the alimen- tary canal, and not wound around it as in the Linguatula: in most species the alimentary canal is attached to the internal parietes of the abdominal cavity by means of numerous small laminated or filamentary processes. In the Strongylus gigas the mouth (A, Jig. 71) is surrounded by six papillae; the cesopha- * .Synopsis Ento?. p. 534. ENTOZOA. 135 gus (b,Jig.. 95) is round and slightly contorted, and suddenly dilates at the distance of about two inches from the mouth into the intestinal canal; there is no gastric portion marked off in this canal by an inferior constriction, but it is conti- nued of uniform structure, slightly enlarging in diameter to the anus. The chief pecu- liarity of the intestine in this species is that it is a square and not a cylindrical tube, and the mesenteric processes pass from the four longitudinal and nearly equidistant angles of the intestine to the abdominal parietes. These processes, when viewed by a high mag- nifying power, are partly composed of fibres and partly of strings of clear globules, which appear like moniliform vessels turning around the fibres. The whole inner surface of the abdominal cavity is beset with soft, short, obtuse, pulpy processes, which probably im- bibe the nutriment exuded from the intestine into the general cavity of the body, and carry it to the four longitudinal vessels, which tra- verse at equal distances the muscular parietes. The analogous processes are more highly de- veloped in the Ascaris lumbricoides, in which species we shall consider the digestive and nutritive apparatus more in detail. The mouth (d, fig. 87 and fig. 85) is sur- rounded with three tubercles, of which one is superior (a, fig. 85), the others inferior (b, b) ; they are rounded externally, triangular inter- nally, and slightly granulated on the opposed surfaces which form the boundaries of the oral aperture (c). The longitudinal muscles of the body are attached to these tubercles ; the dorsal fasciculus converges to a point to be inserted into the superior one ; the ventral fasciculus contracts and then divides to be inserted into the two which are situated below. By means of these attachments the lon- gitudinal muscles serve to produce the divarication of the tubercles and the open- ing of the mouth ; the tu- bercles are approximated by the action of a sphincter muscle. The oesophagus (e,fig. Head and mouth of 87) is muscular and four AscarU lumbricoides. or five lines in length, nar- row, slightly dilated pos- teriorly, and attached to the muscular pa- Fig. 86. Fig. 85. Transverse section of Ascaris lumbricoides, magnified. rietes of the body by means of slender, radiated filaments : its cavity is occupied by three lon- gitudinal ridges, which meet in the centre and reduce the canal to a triangular form. The oesophagus is separated by a well-marked con- striction from the second part of the digestive canal, which in the rest of its course presents no natural division into stomach and intestine. The anterior portion of the canal is attached by filaments, as in the Strongylus, to the pro- cesses and lining membrane Fig. 87. of the abdominal cavity. Those rf which come off from the sides of the canal (d, d) communi- cate with the nutritious vessels and appendages, and in pass- ing from the intestine they diverge and leave on each side a triangular space, of which the base corresponds to the lateral line or vessel (e, fig. 80), and the apex to the side of the intestine. These lateral spaces are filled with a serous fluid, and are continuous with the common cavity contain- ing the alimentary and gene- rative tubes. About the mid- dle of the body the intestine becomes narrower, being here surrounded and compressed by the aggregated loops of the oviduct or testis, and the me- senteric processes or filaments diminish in number, and at last leave the intestine quite free, which then gradually en- larges to within a short dis- tance of its termination (h). The parietes of the intestine are thin and transparent, and easily lacerable ; they consist of a gelatinous membrane, the internal surface of which is disposed in irregular angular meshes and transverse folds, which gradually disappear to- wards the lower part of the canal. The soft obtuse processes (f, ./', fig. 86) analogous to those which project from the lining membrane of the abdo- minal cavityin the Strongulus, acquire a considerable deve- lopment in the Ascaris. They arise chiefly in the dorsal and ventral regions, and are con- tinued from numerous trans- verse bands ( e,e,fig. 88) which pass across the body from one lateral absorbent vessel to the other. In the anterior third of the body these transverse bands (vaisseaux nourriciers, Cloquet,) are quite concealed Digestive and gene- ft the Passes in question rative tubes, Ascaris ( appendices nourriciers, Clo- lumbrkoides, male, quet), but are very conspicu- 136 ENTOZOA. ous at the posterior part of the body. The nervous chord passes at a right angle to the transverse bands between them and the longi- tudinal muscles, and sometimes is included in loops of the former, as at d, fig. 88. Both the pendant processes and the transverse bands are composed of a homogeneous spongy tissue, without any central cavity, and appear to form a nidus of nutrient matter like the fatty omen- tal processes in higher animals. The longitudinal lines (c,c,fig. 86, 88), which extend along each side the body of the Ascaris Lumbricoides, and which are very conspicuous Fig. 88. Nutritive processes and vascular canah magnified, Ascaris lumbricoides. externally through the transparent integument, consist each of a narrow flattened tract of opaque substance, by some anatomists considered as nervous, and a very slender vessel which ad- heres closely to the outer side of the band. The two bands become expanded at the an- terior extremity of the body, and unite in forming a circle around the oesophagus : the vessels, on the contrary, become detached from the bands, and pass transversely below the oesophagus to anastomose together, forming a simple loop or arch, the convexity of which is anterior. By pressure the reddish fluid con- tained in these vessels- may be made to tra- verse them backwards and forwards. With respect to the accessory glands of the digestive system of the Entozoa, I have hi- therto met with them in two species only of the Nematoidea, in both of which they pre- sented the primitive form of simple elongated unbranched cceca. The first being developed from the commencement of the alimentary canal, and co-existing with a pair of rudimen- tal jaws, must be regarded as salivary organs. They exist in a species of worm which infests the stomach of the Tiger, and which I have recently described under the name of Gnathostoma aculeatum.* They consist of four slender elongated cceca, communi- cating with the mouth, and gradually increas- ing in size as they extend backwards into the abdominal cavity, where they end each in a cul-de-sac ; they are placed at equal distances around the alimentary canal, and have no at- tachment except at their open anterior extre- mity. The length of each ccecum is about one-twentieth of the entire alimentary canal. Their parietes under a high magnifying power present a beautiful arrangement of spirally decussating fibres. Their contents when recent are clear, but become opaque when immersed in alcohol. That the Gnathostoma is not the larva of an insect is proved by the complete development of the generative system, which resembles that of the Ascarides, and by the absence of a ganglionic nervous system. The second example of an accessory digestive gland occurs in a species of Ascaris infesting the stomach of the Dugong : here a single elongated ccecum is developed from the in- testine at a distance of half an inch from the mouth ; and is continued upwards, lying by the side of the beginning of the intestine, with its blind extremity close to the mouth ; from the position where the secretion of this ccecum enters the intestine, it may be regarded as re- presenting a rudimental liver.f Respiratory Organs. — The Entozoa have no distinct internal or external organs of respi- ration. The skin in many of the Trematoda and Acanthocephala is highly vascular,^ and the circulating fluids in these worms may be- . come oxygenated by contact with the vascular °°o°&S^y mucous membranes of the higher organized animals which they infest. In the Planarim the surrounding water is renewed upon the vascular surface of the body by means of the currents excited by the action of vibratile cilia; and the young of certain species of Distomata, which pass the first epoch of their existence under the form of Polygastric In- fusoria, freely moving in water, are pro- vided with superficial vibratile cilia arranged in longitudinal rows; but these organj| of lo- comotion and adjuncts to the respiratory pro- cess are lost when the Distomata resume their position as parasites in the intestines of the Fishes from which they were originally ex- pelled. Excretory glands. — As an example of an organ of excretion, we may refer to the glan- dular sac lodged in the enlarged extremity of the Distoma clavatum, which opens externally * Proceedings of the Zoological Society^ Nov. 5, 1836. t See the Preparation, No. 429 A, Mus. Coll. Surgeons, Phys. Catalogue, p. 121. X Conf. Echinorhynchus vasculosus,Entoz.Synop. p. 581. ENTOZOA. 137 by a small orifice in the centre of that part,* and the corresponding cavities from which a clear or milky fluid is ejected by the posterior pores of some smaller species of Distomaia and Diplostomata.f Organs of generation. — The generative sys- tem in the Entozoa presents great varieties in the form, structure, and combination of its several parts. Sometimes the female or productive organs alone are discernible. In many Cestoidea, and in all the Trematoda, the male gland is present and communicates with the oviduct, so that each individual is sufficient for itself in the reproductive capacity. In the Acanthocephala and Ne- matoidea the sexes are distinct, and a con- currence of two individuals is required for impregnation. No trace of a generative apparatus has hither- to been detected in the Cystic Entozoa. They would seem to be gemmiparous, and to have the reproductive power diffused over the whole cyst, at least in the Acephalocysts, in which the young are not developed from any special organ, or limited to any particular part of the cyst. The ovaries in the most simple of the Ces- toid worms, as the Ligula, are situated in the centre of each joint, where they open by a transverse aperture, from which projects a small filamentary process or lemniscus, re- garded by Rudolphi as a male organ. In the Bolhriocephali the ovaries have a similar po- sition, and in the Bothriocephalus latus (Jig. 89) assume a stellated figure, with Fig. 89. the aperture in the centre, T3 /, which is situated in the mid- dle of each joint. In the Bothriocephalus microcephalus the ovary consists of one or two rounded corpuscles in the centre of the joints, but the generative orifices are margi- nal and irregularly alternate, and the oviducts may be dis- tinctly seen passing backwards to them. In the^. Tenia Candelabra- C ria a sacciform ovary exists in each segment, which sends '©Sjj® off an oviduct to the marginal outlet. Besides which, ac- ^^(|P§' cording to Rudolphi, there is (Gaj%} a longitudinal canal, uniting Ovarian apertures the different ovaries together, and ova, Bothrio- and undergoing a partial dila- cephalm latus. tation at the anterior part of each joint. — May not this be the male organ ? The androgynous structure of the generative apparatus is very well displayed in the Tape- worm of this country, the Tania Solium. In each joint of this worm there is a large branched ovarium (i, jig. 90) from which a duct (/i) is continued to the lateral open- Pig. 90. * See Zool. Trans, pt. iv. vol. i. p. 381. ng. 18. See Nordmann, loc. cit. p. 38. t See Nordmann, loc. cit. p. 140. pi. 41. c " e Generative organs maynijied, Tania ing. The ova are crowded in the ovary ; and in those situated in the posterior segments of the body, they generally present a brownish colour, which renders the form of their recep- tacle sufficiently conspicuous.* In segments which have been expelled separately, we have observed the ovary to be nearly empty, and it is in these that the male duct and gland is most easily perceived. For this purpose it is only necessary to place the segment between two slips of glass, and view it by means of a simple lens, magnifying from twenty to thirty diameters: a well-defined line (g), more slender and opake than the oviduct, may then be traced extending from the termination of the oviduct, at the lateral opening, to the middle of the joint, and inclining in a curved or * The dendritic ovarian receptacles can also be injected with mercury or coloured size, and they have been regarded, but erroneously, as forming part of the nutrient apparatus. 138 ENTOZOA. slightly wavy line to near the middle of the posterior margin of the segment, where it ter- minates in a small oval vesicle. This, as seen by transmitted light, is sub-transparent in the centre and opaque at the circumference, indi- cating its hollow or vesicular structure. The duct, or vas deferens, contains a grumous se- cretion ; it is slightly dilated just before its termination. In this species therefore, as also in Amphis- toma conicum, the ova are impregnated in their passage outward. But in several species of Distomata, as D. clavigerum, ovatum, cirrige- rum, and in the Distuma hepaticum, the ova escape by an aperture situated near the base of the penis, and reciprocal fecundation exists. The concourse of two individuals must also take place in those species of the genus Monos- tomum, which, like the Monostomum mutabile, are viviparous, and in which the orifices of the male and female parts are distinct. All the Sterelmintha of the Trematode order are androgynous; but the generative apparatus, instead of being divided and multiplied as in the Taniaz, is individualized, and its several parts receive a higher degree of development. We have selected the figure which Nordmann has given of the Distoma per latum, on account Fig. 91. €f s Generative organs, Distoma perlatum, magnified. of the clearness with which the several parts are delineated, but it must be observed that it deviates in some remarkable peculiarities from what may be regarded as the Trematode type of the reproductive organs. The specimen is seen from the under side, part of the parietes of the body having been removed ; a is the oral aperture, b the oesophagus seen through fhe transparent integument, c d the windings of the beginning of the simple digestive cavity, e e the two intestinal prolon- gations, f f the dilated claviform coecal ter- minations of the intestines, g the two internal, and h the two external trunks of the vascular system proceeding to the anterior part of the body ; i is the great sacciform uterus, k ap- parently glandular bodies contained therein, I m the two testes, which are beset internally with small spines or cilia; n the projecting cirrus from which the ova are expelled, o the terminal dilatation of the oviduct which com- municates with the testes, p p p p convo- lutions of the oviduct which are filled with ova, q q the mass of ova which lies above the ovi- duct, and occupies almost the whole cavity of the body, r r the passages by which the ovaries communicate with the uterus or dilated commencement of the oviduct. The generative organs present some varieties in the Planaria, but are essentially the same as in the Distomata. In the Planaria lactea the penis and oviduct are situated below, and the two vesicular and secerning parts of the apparatus towards the upper part of the body. The male organ (a, Jig. 92) consists, according Fig. 92. to the researches of Professor Duges, of two parts, one of which is free, smooth, semi- transparent, contractile, and always divided into two portions by a circular constriction ; it is traversed by a central canal, susceptible of being dilated into a vesicle, and is open at its free extremity, which is turned backwards ; the second division is thicker, more opaque, vesicular, adherent to the contiguous paren- chyma, and receives two flexuous spermatic canals (6, b). The free portion of the penis is con- tained within a cylindrical muscular sheath (c), which is adherent to the circumference of the base of the intromittent organ, and serves to protrude it externally. This sheath commu- nicates with the terminal sac of the female apparatus near its outlet by a projecting orifice (d). The oviduct (e) opens into the posterior part of the terminal sac : it is a narrow tube which passes directly backwards, and dividing into two equal branches, again subdivides and ramifies amongst the branches of the dendritic digestive organ. Besides the ovary there are two accessory vesicles (gand/i), communicating together by a narrow duct (f ), and opening into the terminal generative sac. M. Baar twice witnessed the copulation of ENTOZOA. 139 Planaria in the species Planaria torva. Upon separating the individuals, he perceived a long white tube projecting from the genital pore of each, proving the reciprocity of fecundation. Notwithstanding the complicated apparatus above described, the Planaria, are remark- able for their spontaneous fissiparous gene- ration, and the facility with which detached or mutilated parts assume the form and func- tions of the perfect animal. Fig. 92, o, repre- sents a Planaria lacteu, with the anterior part of the body artificially divided in the longitu- dinal direction ; Jig. 92, e, shews the same in- dividual having two perfect heads, the result of the preceding operation. The female generative organs of the Lingua- tula ( Pentastoma ) tanioicles present a struc- ture in some respects analogous to that of the DisUnna pcrlatum: the ovary (n, n, Jig. 78) is a part distinct from the tubular oviduct, and is attached to the integument or pa- rietes of the body, extending down the middle of the dorsal aspect. It consists of a thin stratum of minute granules ; clustered in a ramified form to minute white tubes, which converge and ultimately unite to form two oviducts (o, o, Jig. 78). These tubes pro- ceed from the anterior extremity of the ovary, diverge, pass on each side of the alimentary canal, and unite beneath the origins of the nerves of the body, so as to surround the oesophagus and these nerves as in a loop. The single tube (p) formed by the union of the two oviducts above described, descends, winding round the alimentary canal in numerous coils, and ter- minates at the anal extremity of the body. The single oviduct, besides receiving the ova from the two tubes (o, o), communicates at its com- mencement with two elongated pyriform sacs {m, m), which prepare and pour into the ovi- duct an opaque white secretion. These bodies, from their analogy to the impregnating glands in the Trematoda, I was led to regard (in the description, published in the Zoological Trans- actions, of the only individual of this interesting species that I have hitherto been able to pro- cure for dissection,) as testes, and the gene- ration of the Linguatula to be androgynous, without reciprocal fecundation ; individuals, however, of the male sex have since been de- scribed in this species by Miram* and Diesing. The male Linguatula is, as in dioecious Entozoa generally, much smaller than the female : the generative apparatus consists of two winding seminal tubes or testes, and a single vas deferens, which carries the semen from the testes by a very narrow tube, and afterwards grows wider. It communicates anteriorly with two capillary processes, or penes, which are connected together at their origin by a cordiform glandular body, repre- senting a prostate or vesicula seminalis. The external orifices of the male apparatus, accord- ing to Miram, are two in number, and are situated on the dorsal aspect of the body, just behind the head. Diesing, however, describes the male Pen- * Nova Acta Acad. Natura= Cuiios. tom.xvii. tastomu as having only a single penis, which perforates the interspace between the second and first segments of the body, and protrudes below and behind the oral aperture. Much interest attends the consideration of the reproductive organs of the dioecious En- tozoa, since they are the first and most simple forms of the animal kingdom which present that condition of the generative function. In the Acanthocephala the structure of the generative apparatus has been ably elucidated by Cloquet in the species which commonly infests the Hog, viz. the Echinorhynchus gigas. The male organs consist of two testes, two vasa defe- rentia, which unite together to terminate in a single vesicula seminalis, and a long penis gifted with a particular muscular apparatus. The testes (J', ft, Jig. 93) are cylindrical bodies, pointed at both ex- Fig. 93. tremities, of nearly the same magnitude, but situated one a little anterior to the other. The anterior one is attached by a filamentary process (g) to the posterior extremity of the proboscis : the posterior gland is connected by a similar filament to the in- ternal parietes of the body. The vasa deferentia (i), after their union, form seve- ral irregular dilatations (/c), which together constitute a lobulated vesicula seminalis. This reservoir is filled with a white grumous fluid like that which is found in the testes, and it is embraced posteriorly by the retractor muscles of the penis (r, r), which form a kind of coni- cal sheath for it. A small, firm,white, and apparently glandular body (q) is situated at the point of union between the vesi- cula seminalis and the penis. The penis is a straight, cylindrical, firm, white or- gan, and in the retracted state is terminated by a di- lated portion (o), occupying , „ the posterior extremity of Male organs of gene- & b , fa hj , ^ ration, Jzchinorhun- { ' . . r chus gigas. pears when the mtromittent organ is protruded. This action is produced by the muscles s, s, when the penis presents the form of a short broad cone, adhering by the apex to the caudal extremity of the body: it is retracted by the muscles r, ;■, above described. The female organs consist of two ovaries and one oviduct. The former are long and wide cylindrical canals, which of themselves occupy almost the whole cavity of the body extending from the proboscis to the tail (//, h, Jig. 83) They are situated, one at the ventral, the other at the dorsal aspects of the body, and 140 ENTOZOA. are separated in the greater part of their extent by a septum : see fig. 84, J] g, which shows them in transverse section. They contain a prodigious quantity of ova, and adhere by their outer surfaces very firmly to the muscular parietes of the body. The dorsal ovary opens into the ventral one by an oblique valvular aperture about an inch distant from the extremity of the proboscis, anterior to which the common cavity extends forwards between the lateral lemnisci, and terminates by a conical canal {i, fig. 83), which is attached to the posterior portion of the pro- boscis. The two ovaries terminate in a dif- ferent manner posteriorly, the dorsal one end- ing in a cul-de-sac, the ventral becoming continued in a slender oviduct (k), which opens by an extremely minute pore at the caudal extremity of the body (/). The tissue of the ovaries is remarkable for its trans- parency and apparent delicacy, but it pos- sesses a moderate degree of resistance. The generative organs in the Nematoidea are upon the whole more simple than in the Acanthocephala. The testis in each of the genera is a single tube, but differs in its mode and place of ter- mination, and the modifications of the intro- mittent part of the male apparatus have afforded good generic characters. Genitale masculum, spiculum simplex, is the phrase employed by Rudolphi in the formula of the genus Filaria, and this appears to be founded on an observation made on the Filaria jiapillosa, in which he once saw a slender spicu- lum projecting from near the apex of the tail. According to the recent observations of Dr. Leblond,* the male-duct in the Filaria papil- Fig. 94. Penis of Ascaris lumbricoides. * " Quelqucs Materiaux pour servir a l'Histoirc dcs Filaircs ct Strongles, 8vo. Paris, 1836." losa terminates at the anterior extremity of the body close to the mouth. From this aperture the slender duct, after a slight con- tortion, is continued straight down the body to a dilated elongated sac, which represents the testis. In the Ascaris lumbricoides the penis {a, fig. 94) projects from the anterior part of the anus in the form of a slender, conical, slightly curved process, at the extremity of which a minute pore may be observed with the aid of the micro- scope. The base of the penis (b) communicates with a seminal reservoir, and is attached to several muscular fibres, destined for its re- traction and protrusion : the reservoir is about an inch in length, and gradually enlarges as it advances forwards : the testis or seminal tube is continued from the middle of the anterior truncated extremity of the reservoir; it pre- sents the form of a long, slender, cylindrical, whitish-coloured tube, extends to the anterior third of the body, forming numerous convo- lutions and loops about the intestine, and its attenuated extremity adheres intimately to the nutrient vessels of the dorsal region of the body. The total length of the seminiferous tube in an ordinary sized Ascaris lumbricoides is from two feet and a half to three feet. Its contents, when examined with a high micro- scopic power, consist of a transparent viscous fluid, in which float an innumerable quantity of round white globules, much smaller than the ova in the corresponding tubes of the female. In the genus Trichocephalus the fila- mentary testis is convoluted around the intes- tine in the enlarged posterior part of the body. The intromittent organ in the Trichocephalus dispar is inclosed in a distinct sheath, which is everted together with the penis, and then presents the form of an elongated cone (c, Jig. 69), adhering by its apex to the enlarged anal extremity of the body, and having the simple filiform spiculum or penis {d,fig. 69) projecting from the middle of its base. In the Strongylus gigas the bursa or sheath of the penis terminates the posterior extremity of the body, and is a cutaneous production, of a round, enlarged, truncated form, with the spiculum projecting from its centre, as at B, fig. 71. In other species of Strongylus, as in the Strongylus inflexus, the bursa penis is bifid, and in the Strongylus armatus it is divided into four lobes : the obvious functions of these appendages, as of the lateral alaeform cuta- neous productions which characterize the Phy- salopterte and Spiropterg, is to embrace the vulva of the female, and ensure an effective intromission and impregnation of the ova. In the genus Cucullanus, and in most of the smaller species of Ascaris, the intromittent organ consists of a double spiculum. This is also the case in the Syngamus tra- chealis, the parasitic worm before alluded to as infesting the trachea of the common fowl, and occasioning the disease termed the ' Gapes.' In this species the male individual appears as a branch from the body of the female. The testis begins near the middle of the oesophagus by a slender blind extremity, and winds round ENTOZOA. 141 the gut, as it descends, gradually enlarging, to the lower part of the intestine, where it sud- denly contracts and runs down, as a very slender canal, to near the vulva. It is partly covered by two long slender bodies of a horny sub- stance, representing a bifurcate penis. From this comparison of different genera of the Nematoidea, it is seen that, although there are many varieties of structure in the efferent and copulative part of the male gene- rative apparatus, the essential or secerning por- tion uniformly consists of a single tube. A like uniformity of structure does not obtain in the essential parts of the female organs : in a few instances the ovary is single, correspond- ing to the testis in the male, but in the greater number of the Nematoid worms it consists of two filamentary tubes. The Strongylus gigas is an example of the more simple structure above alluded to. The single ovary commences by an obtuse blind extremity close to the anal extremity of the body, and is firmly attached to the termination of the intestine ; it passes first in a straight line towards the anterior extremity of the body, and when arrived to within a short distance from the vulva, is again Fig. 95. attached to the parietes of the body, and makes Jpjk a sudden turn back- »B wards (f,fig- 95); it MvWRk then forms two long AwlHsm. loops about the mid- dle of the body and returns again forwards, suddenly dilating into an uterus (e), which is three inches in length, and from the anterior extremity of which a slender cylindrical tube, or vagina, about an inch in length, (e,d, Jig. 95) is continued, BWjpKK' ft X\ which after forming a ' 1 ■ small convolution ter- minates in the vulva, at the distance of two inches from the ante- rior extremity of the body. Rudolphi was uncertain as to the ter- mination of the ovi- duct in the Strongylus gigas, and Professor Otto, who appears to have mistaken its blind commencement for its termination, believed that the oviduct opened into the rectum. The theory which had suggested itself to Rudolphi of the corre- lation of a simple ovi- Anterior extremity of the duct in the female with Strongylus gtgas, showing ^ splcmum simplex the commencement oj the f , r . A t digestive and the termina- ot tne male, and Ot a Hon of the generative tube, double oviduct with the spiculum duplex, receives additional dis- proof from the circumstance of the uteri and oviducts being double in the Strongylus in- Jiexus and Strongylus armatus. In the former species (which infests the bronchial tubes and pulmonary vessels of the Porpesse, and which I once found in the right ventricle of the heart of that animal,) each of the two female tubular organs may be divided into ovary, oviduct, and uterus : the ovary is one inch in length, commences by a point opposite the middle of the body, and, after slightly enlarging, abruptly contracts into a capillary duct about two lines in length, which may be termed the oviduct, or Fallopian tube, and this opens into a dilated moniliform uterus three inches in length ; the divisions here described were constant in several individuals examined, and cannot, therefore, be considered to result from partial contractions. Both tubes are remark- ably short, presenting none of the convolutions characteristic of the oviducts of Ascaris and Filaria, but extend, in a straight line, (with the exception of the short twisted capillary communication between the ovaria and uteri,) to the vulva, which forms a slight projec- tion below the curved anal extremity of the body. The reason of this situation of the vulva seems to be the fixed condition of the head of this species of Strongylus. In both sexes it is commonly imbedded so tightly in a con- densed portion of the periphery of the lung as to be with difficulty extracted ; the anal extre- mity, on the contrary, hangs freely in the larger branches of the bronchi, where the coitus, in consequence of the above dispo- sition of the female organs, may readily take place. In the Strongylus armatus the two oviducts terminate in a single dilated uterus, and the vulva is situated at the anterior extremity of the body, close to the mouth. We find a similar situation of the vulva in a species of Filaria, about thirty inches in length, which infests the abdominal cavity of the Rhea, or American Ostrich. The single portion of the genital tube continued from the vulva is one inch and a quarter in length ; it then divides, and the two oviducts, after forming several interlaced convolutions in the middle third of the body, separate ; one ex- tends to the anal, the other to the oral ex- tremities of the body, where the capillary portions of the oviducts respectively com- mence. In the Asearis Lumbricoides the female organs (Jig. 96) consist of a vulva, a vagina, a uterus, which divides into two long tortuous oviducts gradually diminishing to a capillary tube, which may be regarded as ovaries. All these parts are remarkable in the recent animal for their extreme whiteness. The vulva (d, Jig. 72,) is situated on the ventral surface of the body at the junction of the anterior and middle thirds of the body, which is generally marked at that part by a slight constriction. The vagina is a slightly wavy canal five or six lines in length, which passes beneath the in- ENTOZOA. testine and dilates into the uterus (/c, fig. 96). The division of this part soon takes place, and the cornua extend with an irregularly wavy course to near the posterior extremity of the body, gradually diminish- ing in size; they are then reflected forwards and form numerous, and apparently inextricable, coils about the two posterior thirds of the intestine. Hunter has successfully unravelled these convolutions, and each of the tubes may be seen in the preparation in the Hunterian Collection to measure upwards of four feet. The generative organs contained in the female, or longer branch of the St/n- gamus trachealis. have a cor- responding structure with those of the Nematoidea. The capillary unbranched ovary and uterus are double, as in Ascaris, Spiroptera, Filaria, and most Stron- gyli. The vulva is in the form of a transverse slit, and is situated at the ante- rior third of the body, im- mediately below the attach- ment of the male branch. In the Nematoidea the male individual is always smaller, and sometimes dis- proportionately so, than the female. At the season of reproduction the anal ex- tremity of the male is at- tached to the vulva of the female by the intromission of the single or double spi- culum, and the adhesion of the surrounding tumid la- bia; and, as the vulva of the female is generally si- tuated at a distance from either extremity of her body, the male has the appearance of a branch or young indi- vidual sent off by gemma- tion, but attached at an acute angle to the body of the female.* In the Heteroura andro- phora of Nitzch (Herscli and Gruber's Encyclopae- die, th. vi. p. 49, and th. ix. * See Figures of Nematoid Entozoa in copulation, in Bremser, Icones Heluiinthum tab. iii. fig. 8. 15. ; and Gurlt, Lehrbuch der Patholog : Ana- tomic der Haus-Saiigethiere, tab. vi. fig. 35. taf. 3. f. 7.) the male maintains a'n habitual con- nexion with the female, which lias a horny pre- hensile process for the purpose of retaining the male in this position. Here there is no conflu- ence of the substance of the bodies of the two sexes ; the individuals are distinct in their su- perficies as in their internal organization. But this singular species offers the transitional grade to that still more extraordinary Entozoon, the Syrtgamus trachealis, in which the male is orga- nically blended by its caudal extremity with the female, immediately anterior to the slit-shaped aperture of the vulva, which is situated as usual near the anterior third of the body. By this union a kind of hermaphroditism is produced ; but the male apparatus is furnished with its own peculiar nutrient system ; and an indivi- dual animal is constituted distinct in every respect, save in its terminal confluence, with the body of the female. This condition of animal life, which was conceived by Hunter as within the circle of physiological possibilities, (see Anim. (Economy, p. 46,) has hitherto been only exemplified in this single species of Ento- zoon ; the discovery of the true nature of which is due to the sagacity and patient research of Dr. Charles Theodore Von Siebold. The Entozoa of the parenchymatous class are chiefly oviparous, those of the cavitary class for the most part ovoviviparous. The germinal vesicle has not yet been dis- covered in the vitelline substance of the ova of the Acantlwcephata, Trematodu, or Ces- toidca ; but it is distinctly discernible in the ova of the Nematoidea ; I have also observed and have figured it in the highly organized ovum of the Linguatula tcenioides. The ova of the Tcenice present considerable varieties of size and form in different species ; Rudolphi has figured seven forms of these ova in the Synopsis Entozoorum, (tab. iii.)* Some are much elongated and pointed at both extremities, others elliptical : the ova of the Bothriocep/ialus lutus are of the latter form, ( L, fig 89) ; those of the Tcenia solium are sphe- rical, as are also the ova of Tcenia jilifor mis. In some species the development of the em- bryo Tape-worm has been observed to have distinctly commenced in the undischarged ova, as in the Tcenia polymorpha. In dissecting a Touraco infested by the 'Tcenia filiformis, we found that the segments of the Taenia in which the ova were most developed had been de- tached from the rest of the body, a process remarkably analogous to that which takes place in the Lernece and Entomostraca, where the external ovaries are cast off, when charged with mature ova. A few of the Trematode Entozoa, as the Monostoma mutabile, produce the young alive ; but these have a very different form from the parent. It would seem that they were des- tined to pass a transitional state of their ex- istence in a fluid medium permeated by light, since two coloured ocelli have been discovered on the head, and the surface of the body is beset with locomotive vibratile cilia. f * Synopsis Entoz. p. 505, pi. iii. fig. 10, 11. f See Siebold, in Wcigmann's Archiv. 1835. ENTOZOA. 143 The ova of the greater part of the Tremutoda are excluded prior to the full development of the fcetus ; they are generally of an oval but some- times spherical form, and many of them singu- larly resemble the seeds or capsules of certain mosses, in having a small circular portion of the outer covering separate from the rest, and closing the cavity of the egg like a lid. Nordmann has studied the development of the young of the Distoma hians, which infest the intestines of the perch. According to this excellent observer the foetus raises, in its en- deavours to slip out of the egg, the small lid, and writhes about for- some time, being still attached to one point of the egg. In about six hours it succeeds in freeing itself from the egg-coverings ; and at this period it differs in every respect from the shape of the parent animal ; the body, which is of a mucous con- sistence and perfectly transparent, is of an oval form ; the anterior mouth forms a small square- shaped projection, and the whole surface of the body is beset with many longitudinal rows of short cilia, which are in rapid and incessant motion, and create a vortex in the surrounding water, similar to that which the Polygastric Infusoria produce. The little animal having its anterior extremity diminish- ing to a point, is well formed for swimming, and by means of its vibratile cilia, quickly darts out of the field of vision when under the microscope. At the distance of one-third of the body from the anterior extremity there is a single coloured eye-speck, from which, when pressed between glass plates, there escapes a brilliant blue-coloured pigment. Thus orga- nized, the young of the intestinal parasite just described move to and fro in water as if this were their natural element, and approximate in form and structure most closely to the Poly- gastric Infusoria of the genus Paramaciuiii, Ehrenb. In this state, doubtless, they are ejected by the Fish, in the intestines of which they were originally developed, into the sur- rounding water, and when again received into the alimentary canal undergo their metamorphosis, lose, like the Lerneae and Cirripedes, the organ of vision which guided the movements of their young and free life, and grow and procreate at the expense of the nutrient secretions with which they are now abundantly provided. In the Cceklmintha the young cast their in- tegument, and would seem in some species, as the Fittirkt Medinaisis, to undergo a change in the form and proportions of the extremities of the body, but they do not possess cilia or ocelli, as in the Trematoda above-mentioned. The ova of the Linguutula are of an oval form : the germinal vesicle is situated near the superficies half-way between the two extremi- ties ; the vitelline membrane is surrounded with a strong cortical membrane : the develop- ment of the fcetus takes place out of the body. In the Strongylus gigas, Strongt/tus injiexus, and a species of Trichosoma infesting the in- testines of the Goatsucker, we have found the fcetus completely formed in the ova contained in the uterus or terminal segment of the gene- rative tube, while those in the ovary or narrow commencement of the same part were still occu- pied with the granular matter of the vitellus. The mature ova of the Strongylus gigas are of an elliptical form, and the embryo within is plainly seen coiled up through the trans- parent coats of the egg; the resemblance which these bear to the Trichina when inclosed in its inner cyst is very striking : the hypothesis suggested by this resemblance need only be alluded to for the purpose of exciting the at- tention of those, who may hereafter meet with the preceding minute muscular parasite, to the existence of larger Nematoid Entozoa in other parts of the body. Cloquet describes the ova in the beginning of the ovaries of the Ascuris Lwnbricoides as consisting of rounded linear corpuscles, pointed at one extremity, thickened at the other; in the middle of the ovaries they as- sume an elongated triangular form, and one of their angles frequently supports a small spherical eminence ; the base of the ovum adheres to the parietes of the oviduct, the apex projects into its cavity. In the enlarged canals, which he terms the cornua of the uterus, the ova are unattached and of a conoid or irre- gularly triangular figure. In the uterus itself they have assumed an ovoid or elliptical form, are surrounded by a transparent glairy mucus, and are composed of a transparent cortical membrane, perfectly smooth on the external surface, and filled with a transparent fluid, in which floats a linear embryo, disposed either in a straight line or coiled up. Cloquet never observed the young Ascarides excluded from the egg in the interior of the uterus, and we equally searched in vain for free embryos in the generative tubes of the Strongylus and Oxyurus above-mentioned, although their de- velopment in regard to form appeared to be complete in the ovum ; the structure of the embryo resembles that of the simpler Vibriones, there being no generative tubes apparent, and the cavity of the body being occupied by a granular parenchyma. With respect to the exclusion of the ova in these and similar ovo-viviparous Nematoid Entozoa, it would appear to be very commonly accompanied with a rupture of the parietes of the body and of the generative tube. Ru- dolphi observes, with respect to the Cucullanus, " Ovula, verme quieto, per intervalla ex vulva pullulent; quin eodem disrupto, quod saepe accidit, ovula vel embryones ex ovariis pro- lapsis parituque ruptis vi quadam et undatim protroduntur." The generation of the Filaria Mediaensis is of the viviparous kind, and the progeny is countless, — " Filaria? nostra," observes Rudol- phi, " prole quasi farctae sunt, quod si harum longitudinem illius vero minutiem spectas, foetuum multa millium millia singulis tribuit." What is most remarkable is, that these em- bryos are not, as in the Sti-ungt/lus and the Nematoid genera above-mentioned, enveloped in an egg-covering, nor are they included in a special generative tube, but float freely along witli a granular substance in the common mus- cular envelope of the cavity of the body. 144 ERECTILE' TISSUE. M. Jacobson," who has recently published a description and figures of the young Filaria Medinensis, compares the body of the mother to a tube or sheath inhabited by the young ones ; and, after a careful examination of three individuals, we have equally failed in detecting either generative or digestive tubes within the muscular sac of the body. The external tunic of the body is a firm subtransparent elastic integument, which, examined under a high magnifying power, presents fine trans- verse striae, occasioned most probably by ad- herent muscular fibres. Within this tunic and readily separable from it are the longitu- dinal muscular fibres, which are arranged in two fasciculi, separated from each other by two well-marked intervals on opposite sides of the body, which are indicated by an impression (or furrow, as the worm dries by evaporation) on the exterior surface. When from long maceration the crisp outer integument has become separated from the longitudinal mus- cular bands, these might be mistaken for two tubes contained loosely within the cavity. 1 believe that these muscular bands are the tubes Jibrineuses, described by Dr. Le Blond f as the alimentary canal and intestine in the fragment of Filaria Medinensis, which he dissected. In a small Filaria Medinensis, containing no vermiculi, we have also failed to discover any distinct tubes for digestion or generation. It is interesting to observe that the young of the Filaria Medinensis do not resemble the parent in form ; one extremity is obtuse, the body slightly enlarges for about one-fourth of its length, then gradually diminishes to within a third of the opposite extremity, which is capillary and terminates in the finest point. The enlarged part of the worm contains a granular substance, and is coiled upon itself, and presents a distinct but minute annulation of the integument : the capillary extremity is smooth, transparent, and generally straight. The Trichocephalus dispar closely resembles in its external form the foetus, if it be such, of the Filaria Medinensis. BIBLIOGRAPHY. — ■ Redi, Osservazioni intorno agli animali viventi che si trovano negli animali viventi, Firenze, 1684. Block, Abhand. von d. Erzeugung Eingewerdwiirmer. Berl. 1782. Goeze, Versuch einer Naturgeschichte der Eingewerdwiir- mer, und Naehtrag dazn. Leipz. 1782-1800. Vol- lisneri, Considerazioni ed esperienze intorno alia generazione de vermi ordinarj del corpo umano. Padova, 1782. Werner, Vermium intestinalium, &c. brevis expositio. Leipz. 1782. Retzius, Lec- tiones publicae de Vermibus intestinalibus, Holm. 1786. Schrauh, Verzeuhniss der bisherigen hin- langlich. bekannten Eingeweidwiirmer, Munch, 1788. Rudolphi, Observ. circa vermes intestinales, 2 fasc. Greifsw. 1793-95. Rudolphi, Entozoorum s. vermium intestinalium historia naturalis, 2 in 3 vol. Amst. 1808-9. Rudolphi, Entozoorum Synop- sis, Berl. 1819. Treutler, Obs. pathol. anat. ad helminthologiamcorp. humani. Leipz. 1793. Zeder, Anleitung zur Naturgeschichte des Eingeweidwiir- * Nouvelles Annales du Museum d'Histoire Na- turelle, torn. iii. p. 80, pi. v. f Quelques Mateiiaux pour servir a. l'Histoire des Filaires et des Strongles, 8vo. 1836. mer. Bamb. 1803. Olfers, De vegetativis et ani- matis corporibus in corporibus viventibus reperiun- dis comment. Berl. 1816. Fucker, Brevis Entozo- orum s. verm, intest. expositio. Vienna?, 1822. Bremser, Ueber lebende Wiirmer in lebenden Mens- chen. Wien, 1819; trad, en francais, par MM. Grundler et de Blainville, Paris, 1825. Bremser, Icones Helminthorum Systema Rudolphii illus- trantes, Wien. 1823. Joerdens, Entomologie und Helminthologie des Mensch. Koerpers. 2Bde. Hof. 1801-02. Lidth de Jeude, Recueil des figures des Vers intestinaux, Leid. 1829. Cloquet, Anatomie des Vers intestinaux, Paris, 1824. Creplin, Observ. de Entozois, Greifesw. 1825-29. Schmalx, De En- tozoorum systemati nervoso, Leipz. 1827. Ejus, Tabulae anatomicae Entozoorum, Dresd. 1831. Le Blond, Quelques materiaux pour servir a l'histoire des filaires et des strongles, Paris, 1836. Mehlis, Obs. Anat. d,e distomate hepatico et lanceolate, Gotting. 1825. Nordinann, Mikrographische Bei- tr'age, 2 Bde. Berlin, 1832. Jacobson, in Nouv. Annales du Museum d'Hist. Nat. torn. iii. Klein, in Philos. Trans, for 1730. Carlisle, in Trans, of the Linnean Society, vol. ii. Laennec, in Bulletin des Sciences de l'Ecole de Medecine, An xiii. Home, in Philos. Trans, for 1793 ; Frisch, in Miscell. Berolinensia, torn. iii. ; and for further re- ferences to numerous papers on the natural history of particular families and species, vide Reuss s Repertorium, &c. Scientiae Naturalis, torn. i. Zoo- logia, &c. Gotting. ; the first vol. of Rudolphi's Entozoorum historia naturalis, and Wieyemann's Archiv fiir Naturgeschichte und Vergleichende Anatomie. (R. Owen.) ERECTILE TISSUE, (tela erectilis ; Fr. tissu erectile ; Germ, das erectile, oder schwell- bare Gewebe,) a structure composed prin- cipally of bloodvessels, intimately interwoven with nervous filaments. This tissue in its ordi- nary state is soft, flaccid, and spongy ; but when influenced by various causes of excite- ment, whether these consist of stimuli directly applied, or operating through the medium of the sensorium, it exhibits the faculty of admit- ting an influx of blood much greater in quantity than what is sufficient for its nutrition, and in virtue of which it suffers a state of turgescence giving rise to a swollen condition, with more or less of rigidity and increased sensibility of the organs into the structure of which it enters, and which state has been long known by the name of erection. From the property of under- going erection peculiar to this tissue, Dupuytren and Rullier first applied to it the term erectile, and the propriety of this distinguishing appel- lation is now very generally admitted by anato- mical authors. The erectile tissue is developed in various degrees in the several parts of the animal economy in which it occurs ; it is abundant and particularly evident in the corpora caver- nosa penis, corpus spongiosum urethras, clitoris, nymphae, plexus retifbrmis, the nipples of the mammary glands, less marked in the red borders of the lips, &c; it also enters into the structure of the papillae of the skin and the villi of the mucous membranes which possess the property of becoming erected in the per- formance of their functions, as is exemplified in the papillae of the tongue. These consist of the pulpy terminations of nerves enveloped by this tissue; in their unexcited state they appear ERECTILE TISSUE. 145 small, pale, soft, and shrunken ; but when excited to erection, they become increased in size, stiff, red, and distended with blood, at the same time that their sensibility is remark- ably exalted. The foregoing remarks apply equally to the cutaneous papillae, particularly those on the pulpy extremities of the fingers, where the sense of touch is developed in its highest degree of perfection. Erectile tissue has also been recognised in the callosities on the buttocks of some of the quadrumana, in the comb and gills of the cock, the wattles of the turkey, and in the tongue of the chamelion.* It is not improbable that this tissue enters into the structure of the and Beclard seems disposed to consider that it exists in the spleen, as well from the appearance which that organ presents when a section of it is made, as from the different states in which it is found on opening the bodies of animals; being sometimes contracted and corrugated on the surface, and at other times plump, smooth, and swollen. In some of the situations above enumerated, the erectile tissue is enclosed in a fibrous sheath which limits its extent and determines the form of the organs in which it occurs ; while in other situations it is deployed superficially, as in the tegumentary organs. It is in the corpora cavernosa penis and corpus spongiosum urethrae, however, that the erectile tissue has been more especially made the subject of anatomical and physiological research ; and the results of the investigations instituted in these organs have been rather inferred from analogy than directly proved as equally applicable to it in all other situations in which its existence has been indicated. According to De Graaf, Ruysch, Duverney, Boerhaave, Haller, and Bichat, the cavernous bodies of the penis and urethra consist of a loose and elastic spongy tissue formed of in- numerable cells, into which, during erection^ blood is poured from the arteries, and from which it is afterwards removed by an absorbing power of the veins. Such an opinion wou^d" accord with the appearances observed o&h examining sections of this structure after having been inflated and dried, but careful examina- tion of it when previously prepared by injec- tion, proves the foregoing opinion to be founded in error. Vesalius, who appears to have directed his attention to the particular nature of this struc- ture in the penis, describes it as composed of innumerable fasciculi of arteries and veins closely interwoven, and included in an invest- ing srieath. Malpighi considered it as composed of diver- ticula or appendices of veins. • Mascagni, who at one time believed in the existence of cells interposed between the veins and arteries, in consequence of subsequent researches abandoned that opinion, and de- monstrated the fact, that a plexus of veins with arteries corresponding, but smaller and less * On the structure and mechanism of the tongue of the chamelion, by J. Houston, in Transactions of the Royal Irish Academy, vol. xv. VOL. II. numerous, formed the corpus spongiosum urethrae, glans, and plexus retiformis, and that the arteries entering this substance terminated in the commencement of veins. Mr. Hunter remarked that the corpus spon- giosum urethrae and glans penis were not spongy or cellular, but made up of a plexus of veins, and that this structure is discernible in the human subject, but much more distinctly seen in many animals, as the horse. &c. Subsequent researches respecting the struc- ture of the penis and clitoris of man, the horse, elephant, ram, &c. have been instituted by Duverney, Mascagni, Baron Cuvier, Tiede- mann, Ribes, Moreschi, Panizza, Beclard, Weber, &c and the result has been a con- firmation of the views developed by Vesalius, Malpighi, and Hunter. Moreschi, in particular, has shewn that the corpora cavernosa penis, corpus spongiosum urethrae, and glans consist of a congeries of fine vessels in all animals, whether covered by skin, hairs, spines, or scales ; and that these vessels, which are principally veins, are characterized by their abundance, tenuity, and softness, which distinguish them from the veins in the muscles and other parts of the body. The annexed figure (Jig. 97) from Moreschi Fig. 97. 146 ERECTILE TISSUE. represents the plexiform arrangement of the veins apparent on the surface of the glans, and which empty themselves into the superficial veins of the penis. Miiller having more recently investigated the structure of the penis, has announced the discovery of two sets of arteries in that organ, differing from one another in their size, their mode of termination, and their use; the first he calls nourishing twigs ( raminutritii), which are distributed upon the walls of the veins and throughout the spongy substance, differing in no respect from the nutritive arteries of other parts ; they anastomose with each other freely,, and end in the general capillary network. The second set of arteries he calls arteria heli- cmm. In order to see these vessels, an injection of size and vermilion should be thrown into a separated penis through the avteria profunda : when the injection has become cold, the corpora cavernosa should be cut open longitu- dinally, and that portion of the injection which has escaped into the cells carefully washed out. If the tissue of the corpora cavernosa be now examined at its posterior third with a lens, it will be seen that, in addition to the nutritious arteries, there is another class of vessels of different form, size, and distribution. These branches are short, being about a line in length and a fifth of a millimetre in diameter; they are given off from the larger branches as well as from the finest twigs of the artery. Although fine, they are still easily recognised with the naked eye ; most of them come off at a right angle, and projecting into the cavities of the spongy substance, either terminate abruptly or swell out into a club-like process without again subdividing. These vessels appear most obvious and are most easily examined in the penis of man, to which the following description refers. These twigs branch off from place to place, sometimes alone, and sometimes in little bundles of from three to ten in number; these, as well as the former, project constantly into the cells or venous cavities of the corpora cavernosa penis. When the arteries thus form a bundle, they arise by a common stem. Sometimes such a vessel, whether it proceeds from the artery as a single branch or as part of a cluster, divides into two or three parallel branches, which also either terminate abruptly, or else swell out near their extremity. Almost all these arteries have this character, that they are bent like a horn, so that the end describes half a circle, or somewhat more. When such a branch so divides itself, there are formed doubly bent twigs inclined one to the other. Many of these arteries enlarge towards their end ; this enlargement is gradual, and is greatest at tome little distance from the extremity, so that the end is somewhat conical, terminating immediately in a rounded point without giving off any branches. The diameter of these arte- rial twigs, in their middle, is from one-fifth to one-sixth of a millimetre : those which branch off from the trunk of the arteria profunda penis are no larger than those which arise from its finest twigs. It is by no means unusual to observe the finest twigs of the arteria profunda giving off branches of this kind which seem much thicker than the twig from which they arose. The annexed figure (fig. 98) (from Muller's Archiv.) repre- sents a portion of the arteria profunda penis of man, with its arteria helicina somewhat mag- nified. These remarkable arte- ries have a great resem- blance to the tendrils of the vine, only that they are so much shorter in proportion to their thick- ness, whence they have received the name arteria? helicina3. Their termi- nations may also be com- pared to a crosier. .By a more minute examination of these vessels either with the lens or with the microscope, it will be seen that, although they at all times project into the venous cavities of the corpora cavernosa, yet they are not entirely naked, but are covered with a delicate mem- brane, which under the microscope appears granular (Jig. 99). After a more forcible in- jection this envelope is no longer visible. When the arteries form a bundle, the whole is covered by a slight gauze-like membrane. With respect to this in- vesting membrane, Profes- sor Miiller appears- to con- sider it as performing an important part in producing the phenomena of erection. These tendril-like arteries have neither on their surface nor their extremities any openings discoverable with the aid of the microscope ; and when the blood, as it is probable, escapes from them in large masses into the cells of the corpora cavernosa during erection, it must either traverse invisible openings, or pass through small openings which become en- larged by the dilatation of these arteries. If the great number of the tendril-like branches of the arteria profunda be compared with the very fine nutritious twigs of the same vessel, it is evident that when the former are filled they must take up the greater part of the blood of the arteria profunda; the diameter of the profunda therefore not only includes its nu- tritious twigs, but also the tendril-like branches, which derive their blood from it, yet pro- bably allow none to pass except during erec- tion ; therefore the blood in the unerected state only traverses the nutritive branches and ar- rives at the commencement of the venous cells in smaller quantities, while during erection it probably passes in considerable quantity into the cells through these tendril-like vessels. Professor Miiller, after pointing out the dif- ference between the tendril-shaped vessels and the looped vessels discovered by Weber in the EXCRETION. 147 villi of the placenta, observes : our vessels are simple; they bend themselves at the end, but do not return to their trunk as a loop, being simply blood-containing processes of the ar- teries which project freely into the cellular cavities of the veins of the corpora cavernosa. These vessels are most numerous in the pos- terior part of the corpora cavernosa ; they occur but seldom in the middle and anterior parts : they are also present in the corpus spongiosum urethra, especially in the bulb; here also they become less frequent anteriorly, and as yet they have not been perceived in the glans. They are much more difficult of detection in the corpus spongiosum urethra than in the corpora cavernosa, where they are very easily exhibited, especially in the human penis. In no other animal have they been found so dis- tinct, or so uniform in their existence as in man. The greater development of these arteries, adds Professor Miiller, in the posterior parts of the organ corresponds with the fact of erection being always earlier evident there, as if the blood distributed itself from thence into the venous cells. During erection blood is accumulated in large quantity in the erectile tissue, but the cause and mechanism of this accumulation are but imperfectly known. Hebenstreit ascribes it to a living power, named turgor vitalis, which exists in different degrees in almost all the textures of the animal body, but most dis- tinctly in the erectile tissue. It still remains, however, to be proved how far erection de- pends on mechanical pressure affecting the veins which convey blood from this structure, and consequent retardation of the venous circu- lation ; and how far it may depend upon an increased flow of blood to its arteries accompa- nied, or perhaps more correctly, occasioned by an increase of sensibility,* or whether it may not depend upon the influence of both these causes combined. • Erectile tissue appears sometimes to be de- veloped as a morbid production, which has been described under the names of varicose tumour, aneurism by anastomosis, na?vus ma- ternus, telangiectasis, &c. Its anatomical cha- racters are of the same kind as those of the [* It must be obvious that the discovery of the arterial lielicince by Professor Miiller favours this theory of erection, as proving the existence of ves- sels distinct from the ordinary ones, which receive and transmit the increased supply of blood to the venous cells. What, in other organs, is effected by a diminished tonicity in the arteries, and a con- sequent enlargement of them, ultimately giving rise to the tortuosity so striking in some cases, is here effected by means of a very peculiar set of arterial processes superadded to the ordinary nutri- tious arteries of the organ. In the pregnant uterus the increased supply of blood is provided for by the enlargement and consequent tortuosity of its ordi- nary arteries ; there are no sinuous veins here to receive the new supply of blood, and consequently erection is not present ; but in the case of the penis this phenomenon occurs in consequence of the existence of the sinuous veins which constitute so large a proportion of the corpora cavernosa. It will be interesting to inquire whether any similar or analogous arrangement of arterial processes exists in other erectile organs. — Ed.] normal erectile tissue ; it varies in size, being more or less circumscribed, sometimes sur- rounded by a thin fibrous envelope; presenting internally an appearance of cells or spongy cavities, but consisting, in reality, of an in- extricable congeries of arteries and veins which communicate by innumerable anastomoses like capillary vessels, but much larger, espe- cially the veins. It is difficult to inject it from the arteries, more easy from the neighbouring veins, which are sometimes much enlarged. This alteration most commonly exists in the substance of the skin, where it sometimes re- sembles the comb and other analogous parts of the gallinaceae. The skin of the face, espe- cially that of the lips, is frequently its seat. It has been observed in the subcutaneous cel- lular tissue in masses of various dimensions, sometimes so large as to occupy an entire limb. It rarely affects the internal organs ; sometimes it extends beneath the mucous membrane of the mouth, mostly in the vicinity of the red borders of the lips. This production is occa- sionally affected by a vibratory motion amount- ing sometimes to a pulsation resembling that of ananeurismal tumour, which is increased by all the causes which excite the activity of the general circulation ; it cannot be properly said that this structure has the property of under- going erection. It is often congenital, some- times it appears to have been produced by accidental causes ; it sometimes remains un- altered ; but it more usually continues to in- crease in size until some of its cavities burst, when hemorrhage of a troublesome description ensues. Beclard considers the hemorrhoidal tumours which occur round the anus as constituting a variety of anormal erectile tissue. Bibliography. — Vesalius de corp. hnmani fabrica, lib. v. cap. xiv. Venet. 1564. De Grauf Regner, De virorum organis, &c. p. 99 et seq. Lugd. Bat. 1668. Malpighi Marcelli opera, omnia, torn. ii. p. 221. London, 1686. Rui/sch FHd., Observatio, C. Amstel. 1691. Haller, Ele- menta, lib. ii. sect. i. §24, et lib. xxvii. sect. iii. 4 10. Mascagni, Prodromo della grande anatomia, Firenze, 1819. Hunter John, On certain parts of the animal economy, Lond. 1786. Moreschi Alex. Comment, de urethras corporis glandisque structura, Mediolani, 1817. Duvernay, in comment. Petro- polit. torn. ii. p. 200. Cuvier, Lecons d'anatomie comparee, torn. iv. Paris, 1799 — 1805. Tiedemtinn, in Journal complementaire, torn. iv. p. 282. Hebenstreit, G. De turgore vitali in Brera Sylloge, torn. ii. Duverney, (Euvres anatomiques, torn. ii. Paris, 1761. Mascagni, P. Hist, vasorum lymphat. sect. ii. Scnis, 1787. Beclard, Anat. generate, Paris, 1823. Weber, H. E. Allgemeine anatomie, p. 415. Braunschweig, 1830. Craigie David, M.D. Elements of general and pathological anatomy, Edin. 1828. Miiller, in Archiv fiir Physiologic, Jahr 1835, p. 202. The paper of Professor Miiller has been very ably translaied in the London Me- dical Gazette, No. 423. (J. Hart.) EXCRETION.— This term is applied to the formation of those fluids in the animal economy, which are destined to no useful purpose in the system, but are intended to be discharged from it, and the retention of which is injurious or 148 EXCRETION. even fatal. The term used by the older phy- siologists was excrementitious secretions. Some general observations may be made on these ex- cretions, with the view both of stating the pre- sent extent of our knowledge on this mysterious subject, and of pointing out the importance of an arrangement and combination of facts re- lating to it, which are usually treated, perhaps, in too unconnected a manner, but the con- nexion of which is already perceptible, and can hardly fail to be satisfactorily elucidated in the progress of physiology. When we shall have more precise informa- tion as to the peculiar, and hitherto obscure principles, which regulate the chemical changes continually taking place in living bodies, it does not seem unreasonable to anticipate, that a dis- covery will be made, connecting the excretions of the body with the assimilation of the food, and with the nourishment of the different tex- tures, a discovery which may be equally as important in illustrating the chemical phenome- na of the living body, as that of the circulation was in explaining those changes which come more immediately under our observation. In the mean time, we can point out a great deal of contrivance, connected with the general function of excretion, and can state what are the general injurious results, when this contrivance fails of its intended effect; but we are unable to explain how the contrivance effects its purpose, or to point out any general law, by which these in- jurious results are determined. I. We may state, in the first place, that the necessity for some kind of excretion, or dis- charge of certain matter from the organized frame, corresponding to the acts of nutrition, or of reception and assimilation of external matter, is a law of vital action, applicable to all organized beings without exception. The uni- versality of the excretion of carbon, (whether pure, or in the form of carbonic acid, we need not now inquire,) has been established by the inquiries of Mr. Ellis and others, and the poi- sonous influence of the carbonic acid, in an un- diluted state, to all living beings, is an equally general fact. In all animals, which possess organs of such size and distinctness as to make their economy matter of observation, other excre- tions are likewise observed; and in vegetables, it is not only certain that various excretions, besides the exhalation of water and of carbonic acid, take place, but it is even believed by De Candolle, that all the peculiar products of vital action, excepting only gum, sugar, starch, and lignine, (which have nearly the same elementary composition, and are convertible into one another,) and, perhaps, fixed oils, are applied to no useful purpose in the economy, and are poisonous to the plants in which they are formed, if taken in by their roots and com- bined with their sap; so that, although often long retained in individual portions of the plants, they all possess the essential characters of excretions* And it appears to be well ascer- tained by the observations of De Candolle and of Macaire, that at least great part of the proper * Physiol. Veget. p. 217. juices of vegetables, which descend chiefly by their bark, and are expelled into the soil, are destined to excretion only, and are noxious to plants of the same species, or even of the same families, if growing in that soil (although often useful to the growth of plants of different fami- lies) ; and this principle has been happily ap- plied by the former author to explain the neces- sity of rotation of crops of different natural families, to prevent deterioration of the produce.* As this necessity of excretion appears to be so general an accompaniment of the vital action of all organized beings, it seems obvious that there must be some general law, which deter- mines the noxious quality of these products of that action, and imposes the necessity of their expulsion. Yet it is certain that the chemi- cal elements which pass off in the excretions, are the same which are found in the textures of the animal body, and in the nourishment, which is essential to animal life. It would appear, therefore, that the noxious property belongs to certain combinations only of these elements, which are formed in the course of the chemical changes in living beings, and which, when once formed, must either be ex- pelled from the body, or else laid up in cells appropriated for the purpose, (as in the case of the resins and volatile oils in vegetables, and of the bile in the gall-bladder in animals,) and kept out of the mass of the nourishing fluid. There is one general fact, on which much stress has been justly laid by Dr. Prout, which is confirmed by M. Raspail, and which may, perhaps, be concerned in determining the noxious qualities of certain compounds, in liv- ing beings, viz. that although the elements which enter into the composition of organized bodies, readily combine, in other circumstances, so as to form crystals, yet the peculiar combi- nations which they form in all the textures which are essential constituents of those organic structures are never crystalline. When a crystal occurs in an organized body, according to Dr. Prout,f it is always either the result of disease, or of some artificial process, or it is part of an excretion, separated from the nourishing fluid and from the useful textures.! Every one of these textures contains, even in its minutest particles, saline and earthy, as well as animal or vegetable matter ; § but the combinations are always so arranged, by the powers of life, that these saline and earthy particles are always dif- fused through membranes, fibres, or cells, never concentrated in crystals. On the other hand, the elements constituting the peculiar matters of the excretions are generally in such a state of combination as readily to assume the crystalline form, either alone, or in the simplest farther combinations of which they are susceptible ; and it seems possible, that this circumstance may be part at least of the cause which necessi- tates their expulsion. This is only matter of * Ibid. p. 249, and p. 1496. t Lectures in Medical Gazette, vol. viii. | " Jamais je n'ai apercu," says Raspail, " de cristaux dans le sein d'une cellule vivante et d'ac- croisemtnt," Raspail, Chimie Organique, § 1378. § Ibid. $1390. EXCRETION. 149 speculation, but that somp such general prin- ciple determines the incompatibility of the mat- ters of the excretions with the life of the struc- tures in which they are formed, can hardly be doubted. II. Although the necessity of various excre- tions is obvious, there is a difficulty, both in the case of animals and vegetables, in fixing on those products of vital action which come exclu- sively under this denomination ; and it appears certain, that some of the organs of excretion (such as the lungs) are at the same time de- stined to other purposes, particularly absorption ; and even that part of certain excreted fluids (such as the bile) is employed likewise in the work of assimilation. But it is certain that the lungs or gills, the skin, the intestines, and the kidneys, are the outlets for excreted matters in all vertebrated animals. 1. There can be no doubt that the watery vapour and carbonic acid which are exhaled from the lungs, are strictly excretions, although it is still doubted by some physiologists, whe- ther the latter substance is truly exhaled, or rather formed at the lungs; on the latter sup- position we should say, that the excretions of the lungs are water and carbon. It appears certain, from some experiments of Dr. Gordon, that no animal or saline matter escapes by this outlet. The total amount of loss by this excretion in twenty-four hours, in a middle-sized man, has been stated by Lavoisier and Seguin as aver- aging about fifteen ounces ; and it must be re- membered, that as we have good evidence of very considerable absorption at the lungs, the whole quantity of matter excreted must consi- derably exceed this weight. Indeed, Mr. Dal- ton estimates the exhalation of watery vapour only from the lungs at twenty-four ounces in the day. Some have estimated the quantity of carbon alone escaping in this way in the day at eleven ounces; but this estimate is probably exaggerated. It seems to be ascertained by the experiments of Dr. Edwards, of Despretz, and Collard de Martigny, that there is at times an obvious exhalation of azote by the lungs; and Dr. Edwards expresses an opinion that there is probably, at all times, both an exhalation and absorption of that gas, but that these processes in general nearly compensate one another. According to Dr. Prout's views, re- cently, though briefly, announced, we may, per- haps, state the source and cause of the forma- tion of the carbonic acid, and assign the use of the excretion of the water, which escapes by the lungs, with more precision. He supposes the acid to be evolved in the course of the circula- tion, by that " process of reduction," by which the gelatin of the animal textures is formed from the albumen of the blood ; and the water to be given off chiefly /rom the weak albuminous matters of the chyle, and to be an essential part of the " process of completion," by which this is converted into the strong albumen of the blood? 2. The excretion by the skin is chiefly See IJridgewater Treatise, p. 524. watery vapour; the escape of carbon, or carbonic acid, by this outlet appears to be to a very small amount, and to be very variable. In the sen- sible perspiration or sweat there is an excess of lactic acid, a small quantity of the same animal and saline matters as are contained in the serum of the blood, and a little oily or fatty matter, probably from the sebaceous glands ; the whole loss by this excretion in the human adult has been stated as averaging about thirty ounces in the day, but is evidently liable to very great variety. Many experiments prove that there is much less compensating absorption by this tex- ture than by the lungs. 3. The excretions by the bowels are, properly speaking, only those parts of the alvine evacua- tions, which are secreted within the body itself, and mixed with the residue of the food. It is probable that part of the secretions from all parts of the prima viae are thus excreted, but the only one of which it has been ascertained that it is, in part at least, destined necessarily for excretion, is the bile. It is certain that the peculiar animal matter of this secretion, (re- garded by some as of pretty simple and by others as of very complicated composition) is never found in the healthy state in the lacteal vessels or thoracic duct — that it is found in full quantity along with the residue of the aliments in the lower intestines, — that it is increased in quantity when the excretion of urine is sup- pressed in animals by extirpation of the kid- neys ; and again, that when this secretion is sup- pressed, the urine is increased and altered ; and we can therefore have no difficulty about regard- ing this part of the bile as strictly an excretion, notwithstanding that we have good evidence, that at least the alkali of the bile is of use in the digestion and assimilation of the food. Of the quantity of matter strictly excreted from the intestines in the day it must of course be very difficult to judge. The chemical elements that escape in the biliary matter must be chiefly carbon and hydrogen. 4. The urine is the most complex of the ex- cretions, particularly as to saline impregnation, containing not only the salts which are detected in the blood, but a portion of every earthy and saline matter that can be found in any part of the body, besides the peculiar and highly azo- tised animal matters, lithic acid and urea. The average quantity of urine passed in twenty-four hours may be about forty ounces, but is very liable to variation, particularly by temperature, being generally greater, as the excretion by the skin is less. The quantity of solid matter, animal, earthy, and saline, that passes off in this way has been stated at about fifteen drachms on an average, and is evidently much less liable to change, the density of urine, in the healthy state, always diminishing as its quantity increases, and vice versa. The milk, and the semen, although destined to no useful office in the system in which they are formed, are rather to be called recrementilious secretions than excretions. Yet the former has this property in common with excretions, that its retention within the body, when the conditions of its formation exist, i^ 150 EXCRETION. hurtful. The menstrual discharge may be regarded as strictly an excretion, though one which is required only in the human species and for a limited time. Berzelius stated several distinctions, which he thought important, between the excremen- titious and recrementitious secretions in the animal body, particularly that the former are always acid, that each of them contains more than one animal matter, and that their salts are more numerous and varied than those in the blood, while the latter have an excess of alkali from the same saline ingredients as the serum of the blood, and each contains only a single animal principle, substituted for the albumen of the serum. But these distinctions are cer- tainly inapplicable in several instances, and the only one of them which appears to be a general fact, is the more complex saline impregnation of the excreted fluids. III. It is unnecessary to dwell on the well- known injurious effects, on the animal oeconomy, of the suppression of any of these excretions. It may, indeed, reasonably be doubted, whether the rapidly fatal effects of obstructing the ex- posure of the blood to the air at the lungs are owing to the retention of carbon, or carbonic acid ; it seems much more probable that the cause which stops the circulation at the lungs in asphyxia, is the suspension of the absorption of free oxygen into the blood, rather than the suspension of the evolution of carbon or car- bonic acid. But even if the circulation could be maintained, after the exposure of the blood to the air is suspended, we know that the carbonic acid which we have good reason to believe would soon be in excess in the blood, would then act as a narcotic poison. Of the effects of suspension of the excretion by the skin we can- not speak with certainty, because that is a case which probably hardly ever occurs ; and if it were to occur, the lungs and kidneys would probably act as perfect succedanea. But it is worthy of notice that at a time when the skin is known to be nearly unfit for its usual functions — during the desquamation that succeeds exan- the.matous diseases, and especially scarlatina, — the lungs and the kidneys, on which an unusual burden may thereby be supposed to be thrown, are remarkably prone to disease. The effect of suppression of the excretion of urine (i. e. of ischuria renalis), whether occurring as a disease in man, or produced by extirpation of the kid- neys in animals, is uniformly more or less of febrile symptoms quickly followed by coma and death ; and in these circumstances it is now known, that the urea may be detected in the blood. A variety of morbid affections, and particularly an affection of the nervous system marked by inaptitude for muscular or mental exertion, always follows the obstruction of the excretion of bile, and absorption of bile into the blood constituting jaundice. There are a few cases of intense jaundice which terminate in coma and death as rapidly as the ischuria renalis does, and with as little morbid appearance in the brain to explain this kind of fatal termination ; and in several such cases the remarkable phenomenon has been observed after death, that the bile-ducts have been pervious and empty.* It is obvious, that it is this last circumstance only, that can make a case of jaundice analogous to cases of the ischuria renalis. If it shall appear to be a general fact, that the cases of jaundice presenting this remarkable appearance on dissection are those which terminate with unusual rapidity in the way of coma, the analogy will appear to be complete ; and when such cases are compared with those, much more frequently occurring, where the excretion of bile is only obstructed, not suppressed, and where months frequently elapse without any bad symptom occurring, — it appears a reason- able conjecture, that the retention in the blood of matters destined for excretion, is more rapidly and certainly injurious than the re- absorption of matters which have been excreted from the blood at their ordinary outlet, but not expelled from the body. Although there is still much obscurity in regard to the intention of the menstrual dis- charge, yet it may be stated as a general fact, that the suppression of this evacuation is more frequently followed by injurious effects (particu- larly affections of the nervous system, or vica- rious hemorrhage) than the stopping of an equal amount of haemorrhage, going on equally slowly, would be ; so that the general principle applicable to other excretions is exemplified here likewise. IV. The next question in regard to the ex- cretions is, in what manner they are effected ; and on this question, although we must profess ignorance in the last result, yet it is instructive to observe, what seems now to be well ascer- tained, that the large size, and apparently com- plex structure, of several of the organs of excre- tion, appear to be no part of the contrivance for the formation of these fluids from the blood. It is stated by Cuvier, as the result of a general review of the structure of glandular organs in different classes of animals, that pro- ducts very nearly resembling each other, and evidently answering the same ends, are formed in organs where the structure, and the disposi- tion of vessels are very various ; and again, that substances the most widely different are formed in organs that are in these respects ex- tremely similar ;f and that this should be the case will not appear surprising when we consider the result of the most minute and accurate observations on the ultimate structure even of those secreting organs, which form substances the most dissimilar to the general nourishing fluid, either of animals or vegetables. " Chaque cellule de la structure vegetale," says De Candolle, " peut etre considered comme une vesicule organique et vivante, qui est entouree, ou de cavites dans lesquelles abordent des liquides, ou de cellules remplies elles-memes de * See Marsh in Dublin Hospital Reports, vol. iii. Two cases of exactly the same description have oc- curred within these few years in the Edinburgh Clinical wards. t Lecons d'Anat. Comp. t. v. p. 214. EXCRETION. 151 liquides. Cette vesicule, par sa vitalite propre, absorbe une partie du fluide qui l'entoure ; ce fluide est ou de l'eau presque pure, et alors elle en est simplement impregnee et lubrifiee ; ou de l'eau plus ou moins chargee de cette matiere gommeuse, elaboree dans les feuilles, et d'autres matieres alimentaires qui peuvent se trouver portees avec la seve dans les diverses parties. Lit vesicule qui Pa absorbte lui J'ait subir une action determin'ce d'apres sa propre nature, et cette action modifie les materiaux contenus dans la cellule, de maniere a en faire, ou l'une des matieres communes que nous avons considerees, ou l'une des matieres que nous aurons bientot a examiner, telles que les huiles volatiles, les resines, &c. Certains vaisseaux analogues a la nature des cellules jouent le meme role sous ce rapport. Les matieres ainsi localement elaborees peuvent, ou rester dans les cellules ou les vaisseaux qui leur ont donne naissance, ou s'extravaser au dehors et donner lieu, soit a des excretions, soit a des transports des matieres d'une partie a 1 'autre du tissu."* The description given by Dutrochet of the act of secretion as it may almost be detected in the glands of the lower classes of animals, is exactly similar. " Entre les vesicules qui composent le tissu organique des animaux rampentles vaisseaux sanguins, chez les animaux a circulation : ces vesicules sont appliquees sur les parois des vaisseaux ; et il est certain que la cavite des vesicules ne communique point immediatement avec la cavite des vais- seaux, puisque le meme fluide n'existe point dans leurs cavites. Ce fait est tres facile a verifier, en examinant au microscope le tissu d'un organe secretive chez un mollusque gas- teropode, celui de la foie par example : on voit toutes les vesicules de cet organe remplies par la bile, que Ton distingue a sa couleur, tandisque les vaisseaux sanguins qui cotoient ces vesicules n'ont que la diaphaniete que leur donne l'etat incolore du sang qui les remplit. Ainsi, les vaisseaux sanguins n'existent que comme des moyens d'irrigation pour les vesi- cules qu'ils cotoient, et ce n'est peut-etre que par filtration que le fluide sanguin penetre, en si modifiant, jusque dans ces vesicules elemen- taires. Le systeme sanguin, considere dans son entier, forme une cavite sans issue, dans laquelle rien ne peut entrer, et de laquelle rien ne peut sortir, autrement que par filtration."f Any one who is acquainted with the elabo- rate " Vasorum Lymphaticorum Historia" of Mascagni, will recognize the perfect accordance of this statement with the result of his careful and minute investigation of the structure of the secreting organs in the higher animals.} We may consider, then, the act of secretion, en derniere analyse," as consisting simply in * Physiol. Vegetale, p. 215. t L'agent immediat du mouvement vital devoile, &c. p. 192. J It must Dot be considered as ascertained, that the files or tracks of globules of blood seen under the microscope, and usually called capillaries, have really, in all animals, aud all parts of these, vascular coats. It seems pretty certain, that in the passage of certain portions of a compound fluid through a thin living membrane, and the exclusion of others; or, according to the for- tunate expression of Dutrochet, as a chemical filtration. " All that is necessary for any kind of secretion in a living animal," says Mr. Mayo, " is a vascular membrane, and all the arrangements of the glands appear to be merely contrivances for conveniently packing a great extent of such a surface in a small compass." And if we are asked, to what cause we can ascribe this escape of certain matters from the circulating fluid through one portion of mem- brane, and of others through another, we can only answer, in the words of this last author, that it depends on the exercise of certain " vital affinities,'' peculiar to the living stale, and the existence of which will always be an ultimate fact in Physiology, although we may attain to a knowledge of the laws according to which they operate. V. One principle may already be laid down, almost with certainty, as to the exercise of these powers in the present instance, viz. that the peculiar matters characterizing the excretions are not actually/brmerf from the blood at the parts where they appear, but only separated from the blood at these parts, — their formation, if not actually completed, having been at least considerably advanced, in the blood itself which reaches these parts. Of this we are well assured, chiefly by the following facts. 1. The experiments already mentioned, first made by Prevost and Dumas, have proved that within a short time after the extirpation of the kidneys in animals, urea may be detected in the blood, showing clearly that the existence of these glands is not necessary to the forma- tion of this very peculiar excrementitious matter, and giving us reason to conjecture that the office of the kidneys is, not to form the urea, but to attract it out of the blood as fast as it is formed there. The same existence of urea in the blood has been ascertained in the human body, both in cases of diseased kidneys, when the excretion there was much impeded, and in cases of malignant cholera, when the excretion was suppressed. The cases of rapidly fatal jaun- dice al ready mentioned, where the bile-ducts were pervious and empty, would seem to have been cases where the peculiar matter of the bile has been in like manner formed in the blood, without finding the usual vent at the liver. And it will appear under the head of Respira- tion, particularly from the experiments of Dr. Edwards, and of Collard de Martigny, that there is good reason to believe the carbonic acid of expired air to be formed in the course of the circulation, and only exchanged for oxygen at the lungs. 2. There are various instances in disease, of substances generally found in the secretions of certain glands only, being deposited in situa- tions quite unusual, and where no texture similar to these glands exists; e. g. cholesterine, many cases they are only lines or membranes, or channels in a solid parenchyma ; but still the obser- vation in the text applies strictly to the escape of any particles of the circulating fluid from them. 152 EXCRETION. which in the natural state is found only in the bile, has been found deposited in diseased structures in the brain, kidneys, pelvis, scro- tum, &c. ; and lithic acid, naturally existing only in the urine, is deposited in cases of chalk- stone in the textures immediately surrounding the joints of the fingers and toes. It seems to be nearly in like manner that purulent matter, when mixed in unusual quantity with the blood, as by inflammation of a vein, is fre- quently deposited in individual parts of the body, with little or none of the usual sym- ptoms, or of the other accompaniments, of in- flammation at these parts. 3. There are a considerable number of cases recorded on unexceptionable evidence, where excretions have passed off per aliena cola, i. e. by organs which in the natural state yield no such products, and the structure of which is widely different from that of the glands where they are usually secreted. This has been most frequently observed of the milk and of the urine, and of the latter, both in cases where the secretion at the kidneys had been sup- pressed, and in cases where its discharge by the urinary passages has been obstructed, so as to occasion its re-absorption. In both cases it is obvious that the peculiar matter of this excretion must have been first mixed generally with the blood, and then deposited in indivi- dual parts of the system, widely different as well as distant from those where it usually appears. In cases of this kind collected by Haller,* the vicarious discharge of urine is stated to have occurred from the skin, from the stomach, from the intestines, and from the nipples; and in cases recorded by Dr. Arnold and Dr. Sen- ter in America, it is stated to have been passed by vomiting, by stool, from the nose and from the mammae, as well as other parts.f Both in cases given by Haller, and in one recorded in Magendie's Journal de Physiologie, (vol. vii.) milk is stated to have been evacuated in quan- tity from pustules that formed on the thigh ; and among the former are instances of its hav- ing passed off from the salivary glands, the kidneys, and the uterus. Such statements were formerly considered as fabulous, but since the facts already mentioned (and particularly the appearance of urea in the blood after ex- tirpation of the kidneys) have been ascertained, this scepticism seems no longer reasonable. It must be here observed, that the healthy blood is easily shown to contain in itself mat- ters more nearly akin to all the solid textures and to the other secreted fluids of the body, than to the bile and the urine ; and hence, if we are satisfied that the elaboration of these latter fluids is effected in the blood itself, and does not essentially require any special action of the organs in which they usually appear, there can be little hesitation about extending this inference to other acts of secretion and to nutrition. It appears, therefore, at least highly probable, that the whole processes of as- similation and elaboration of the fluids in the * Elem. Phys. lib. vii. ch. 1. t London Med. and Phys. Journal, 1828. living body are carried on, as other chemical changes on fluids are, in the interior of these fluids themselves, and that the solids of the body are concerned in these changes only in two ways : first, by securing the complete sub- division and intimate intermixture of the fluids necessary to their chemical changes ; and second- ly, by determining the parts of the body where peculiar matters, already existing in the blood, shall be deposited from it, or attracted out of it. VI. We may next enquire, what is the most probable original source of the matters which are thrown out of the body in the way of ex- cretion. As it is generally believed, and on strong grounds, that the solid textures, as well as prepared fluids of the body, are liable to continual decay and renovation, it has long been the general belief, that the materials for the ex- cretions are supplied chiefly from those sub- stances which have formed part of the textures, and, after fulfilling their office there, have been taken back into the circulation with a view to their discharge from the body. And it has been conjectured, certainly with much probabi- lity, by Berzelius and by Autenrieth, that the animal matters thus mixed with the blood on their way to the excretories, are distinguishable from the albuminous or nutritious parts of the blood, by their solubility both in hot and cold water, and constitute the animal matter of the serosity, or uncoagulable animal matter of the blood. This is supported by the observation, that, when the kidneys are extirpated, this part of the blood is first observed to increase in amount, and afterwards it is here that the urea is detected.* And the connexion of the excretions with absorption from all parts of the body seems farther illustrated by the pheno- mena of diabetes, which may be held to be the disease in which there is the strongest evidence of increased absorption in all parts of the body, from the rapid digestion, the rapid recurrence of thirst after drinking, the dryness of the sur- face, and the progressive emaciation notwith- standing the excessive amount of ingesta ; and in which the quantity of the urine is often ten times, and the solid contents of the urine often twenty times, the average quantity in health.f But it should not be too hastily concluded, that all the solid constituents of the animal body are liable to continual absorption and renova- tion. The permanence of coloured marks on the skin, noticed by Magendie, is sufficient evidence, that, in some of the textures, any such change must go on very slowly ; and some of the best observers doubt whether any such pro- cess of alternate deposition and absorption takes place in vegetables, in which, nevertheless, as we have seen, excretion is a necessary process. * Provost ct Dumas in Ann. de Chimie, t. xxiii. p. 97. t The change of nature of the animal part of this solid matter, (viz. the disappearance of part of the urea, and substitution of an excessive quantity of sugar,) is evidently connected with the singular fact ascertained by Dr. Prout, that sugar differs from urea simply in containing no azote, and a dou- hle quantity of carbon and oxygen : a discovery which will, probably, acquire a greatly increased importance in the progress of organic chemistry. EXCRETION. 153 Dr. Prout has lately stated strong reasons for thinking, that great part of the contents of the lymphatic vessels are not excrementitious, but destined for useful purposes in the animal eco- nomy; remarking particularly on the way in which hybernating animals appear to be nou- rished by absorption of their own Jut* And it is obviously possible, that the excre- tions may be required to purify the blood of matters taken in from without, or evolved in the coui^se of the circulation and its abundant changes, as well as to purify it of what has been absorbed from the system itself. Now that we know, that great part of the ingesta into the stomach are taken up by the veins, and pass through the liver on their way to the heart ; and, likewise, that the venous blood is the chief source of the excretions of bile, it seems pro- bable, that one important use of this excretion is, to subject a part of the ingesta to a second filtration, or rejection of part of their ingre- dients, subsidiary to that which they undergo in the primae via?. This may also be probably one principal reason why the great mass of the chyle, and other products of absorption in the body, should be mixed with the blood just before its concentration at the heart, and subsequent dif- fusion through the lungs ; and thus participate in a purification, by the rejection of water and carbonic acid, before they are applied to the purposes of nutrition. We know, that in birds, reptiles, and fishes, there is a venous circulation similar to that of the vena porta?, through the substance of the kidneys, of most of the blood coming from the lower half of the body ; a part of the ingredients of that blood will, there- fore, be evolved with the urine; and, in the case of the reptiles, it has been lately ascertained, that this venous blood receives, before entering the kidneys, the contents of numerous and large lymphatics.f At all events, if we are right in supposing, that, in the higher animals, all the great chemi- cal changes which are wrought on the blood, even the formation of the excretions, are effected during its circulation in the bloodvessels them- selves, we can thereby acquire a general notion of the intention of several contrivances, the use of which is otherwise very obscure. We can understand, that the object of the concentration of the blood at the heart may be not merely mechanical, but, partly, also chemical ; and we can see the intention of the heart being so ad- mirably adapted, by the articulated structure of its internal surfaces, not only to receive and propel, but also most effectually to intermix, all the component particles of the blood, both be- fore and after its exposure to the air ; the most perfect illustration of which power of the heart is afforded by the effect it produces on any com- pressible and elastic fluid which is received in a mass of any considerable volume into its cavi- ties, and which is necessarily subdivided into so many minute globules, and compressed in so many directions, that it cannot escape from the heart, and so stops the circulation. * Bridgcwater Treatise, p. 515, et seq. t M'uller, in Phil. Transactions, 1833. Again, when we attend to the manner in which substances foreign to the circulation are absorbed into it, whether from the system itself, or from without, we see a great deal of contri- vance, evidently adapted, andprobably intended, to secure the most gradual introduction, and the most perfect intermixture possible, and to allow the escape of certain parts of the compound fluid formed. Thus of the contents of the primae via?, part are absorbed into the veins, and sent through the capillaries of the liver and those of the lungs, (both admitting of excretion,) before they are admitted into the arteries. What is taken up by the lacteals has already undergone much elaboration by living fluids ; this portion passes through the mesenteric glands, and is, probably, so far intermixed with the blood there, and partly received into the veins passing from them to the liver;* and the rest is mixed with much matter flowing from other parts of the system by the lymphatics; and, according to the views of Dr. Proutt as to the nature of absorption, is so far assimilated by this mixture also, before it is poured into the great veins in the state of chyle, to undergo the thorough agitation at both sides of the heart, and to participate in the changes at the lungs. What is absorbed from other parts of the body seems to be partly taken up by the veins, partly also by lymphatics which immediately convey it into adjacent veins; the remainder passes through lymphatic glands, and is there pretty certainly subjected to an intermixture and an interchange of particles with blood; after which it has necessarily much further adm'ix- ture, and two thorough agitations at the heart, as well as the exposure at the lungs, to undergo, before arriving at the left side of the heart. In those of the vertebrated animals which have no lymphatic glands, the thorough inter- mixture of the fluids contained in the lymphatic vessels is provided for by numerous plexuses,}: and, in the case of reptiles, by distinct lympha- tic hearts communicating with veins ;§ and we are sure, that much of the matters absorbed in these animals, whether by veins or lymphatics, passes through the capillaries of the kidneys or liver, as well as the lungs, before reaching the arteries. When we see so much contrivance, evidently adapted for giving every facility to the gradual operation of the vital affinities subsisting among the constituents of the blood, before it reaches the scene of any of the acts of nutrition, secre- tion, or excretion, we cannot be surprised to find, that these acts themselves should appear to be so simple as the observations already quoted would seem to indicate. It must be admitted, that if we consider these contrivances in the higher animals as important agents in the elaboration of the blood, and con- sequent formation of the textures and prepared fluids of the body, there is a difficulty in under- standing how these objects can be accomplished * Tiedemann et Gmelin, Recherches, &c. t Bridgewater Treatise, ubi stipra. t Cuvier, Lemons, &c. t. iv. p. 98. § Miiller, ubi supra. 154 EXTREMITY. in the lowest classes, particularly the insects and zoophyta, where the nourishment of various textures, and formation of secretions and excre- tions, has been thought to be merely in the way of imbibition from a central cavity.* But it is to be observed, that in several of these tribes, in insects, and even in the infusory animals, recent observations have disclosed a much more com- plex apparatus for the movement of the fluids, than was previously suspected. And, in regard to the lowest zoophyta, it may be said in general, that if there is little apparent provision for the elaboration of the fluids, there is also little occasion for it,— first, because there is little variety of textures to be nourished, and secondly, because the simplicity of their structure is such, that all the particles of their nourishing fluid, — -admitted into a central cavity, flowing thence towards their surface, and acted on by the air at all parts of that surface, — are similarly situate in regard to all the agents by which they can be affected, and must be equally fitted for the changes which the vital affinities there acting on them can produce, so that the same necessity for gradual intermixture, and repeated agitation, of heterogeneous mate- rials, does not probably exist in them, as in the animals of more complex structure. The analogy of their economy, therefore, is not a serious objection to the inference we have drawn from so many other facts, as to the numerous changes which are wrought in the blood of the higher animals, while circulating in the vessels, and as to the function of excre- tion being a necessary accompaniment of the assimilation of aliment, and nutrition of tex- tures, even independently of their renovation by processes of ultimate deposition and absorption . C W. P. Alison.) EXTREMITY, (in human anatomy), mem- brunt, artus; Gr. ^eXo;, zaXov ; Fr. extremit't, membre ; Germ. Gliedmassen ; Ital. membro. This term is used to denote certain appendages most manifest in the vertebrated classes of animals, employed as instruments of prehen- sion, or support, or motion, also occasionally employed for other purposes sufficiently in- dicated by the habits of the animal. In fa- miliar language we apply the word, limb, synonymously, and the superior and inferior limbs of man, or the anterior and posterior ones of the Mammiferous Quadrupeds, are the best examples by which we can illustrate our de- finition. When these appendages exist in their complete number, i. e. four, they are distin- guished either by the appellatives already mentioned, anterior and posterior, or superior and inferior, or more precisely pectoral, and pelvic or ventral, or again atlantal and sacral. In Fishes we find that in most instances the anterior limbs (pectoral fins) are larger than the posterior (ventral fins) : and sometimes the posterior are absent altogether, as in the com- mon eel. In Fishes we look for the simplest form of the skeleton of the more highly de- veloped limbs in Man and Mammalia : and * Cuvicr, Le^ns, &c. 27. here we find, more or less obviously in differ- ent instances, the same elements which sub- sequently appear in a more distinct and com- plete form. Thus, in the case of the Lophius piscatorius, we find very distinctly the scapula and clavicle forming the bond of connection of the other bones of the limb to the trunk. We can also recognize the radius and ulna, what seems to be a very rudimentary humerus, and the bones of the carpus, as well as the phalanges, which generally greatly exceed in number any arrangement that is to be found in the higher classes. The ventral fins, how- ever, the analogues of the posterior extremities, are not so developed : while bones analogous to the phalanges of the feet are found in it, we meet no trace of the femur, tibia, or fibula In all the other Vertebrata we find the an- terior and posterior extremities developed on a plan similar to that in man, with such vari- ations as the manner of life of the animal requires. We must, however, notice an excep- tion in the case of serpents and Cetacea. In the former there are no limbs, or at least the merest trace of them ; in the latter the pos- terior are absent, although the anterior exhibit very perfectly all the elements of the human upper extremity. We propose to devote the present article to the detail of the descriptive anatomy of the osseous system of the extremities in Man, in whom, by reason of his erect attitude, the terms superior and inferior are substituted for anterior and posterior, as applied to the ex- tremities of the lower animals. Superior extremity. — The superior extremity is connected to the trunk through the medium of two bones, which, as being intimately con- nected with the motions of the limb, first de- mand attention. These bones are the clavicle and scapula, and are commonly called the bones of the shoulder. Clavicle (from clavis, a key;) collar-bone ; syn. ligula, jugulum, os furcate; Germ. Schlus- selbein. This bone is situated at the upper and anterior part of the thorax, and forms the anterior part of the shoulder : its direction is from within outwards, so that its external end, which is articulated with the scapula, is pos- terior, and on a plane superior to its internal end, which is articulated with the sternum. It thus constitutes the key to the bony arch formed at the shoulder, and hence its integrity is especially necessary to the integrity of the motions of the shoulder. The clavicle is a long bone, cylindrical, and so curved as to resemble the italic f placed horizontally. Its internal extremity is thick and rounded, while its external one is flat- tened ; of its two curves one is internal, with its convexity directed forwards ; the other ex- ternal, with its convexity directed backwards. The internal extremity, also called sternal, is formed by a gradual expansion of the shaft of the bone, which, however, still preserves the general cylindrical form, but is flattened a little on its superior surface : in size this ex- ceeds all other parts of the bone. The inner surface of this extremity of the clavicle is EXTREMITY. 155 destined for articulation with the sternum, and accordingly we find on it a considerable arti- cular facet, which is convex from above down- wards, and concave from before backwards. The outline of this surface is triangular, and each angle is easily distinguishable by the degree of its prominence : thus, one angle is situated anteriorly and inferiorly, it is the least prominent ; a second is posterior and inferior, it is the most prominent; and the third is su- perior, and may easily be felt under the inte- guments in the different motions of the bone. The external or acromial end of the clavicle is at once distinguished by its flattened appear- ance; it is flattened on its superior and in- ferior surfaces. At its extremity we find an elliptical articular surface adapted to a similar one upon the acromion process ; this surface is nearly plane, its long axis is directed horizon- tally from before backwards. The body or shaft of the bone presents se- veral points deserving of notice. The superior surface is smooth and rounded, expanding to- wards the sternal end, where it affords attach- ment to the clavicular portion of the sterno- mastoid muscle. It expands likewise towards the acromial end, but loses the cylindrical form and becomes flattened : the central part is the most contracted and the most cylindrical; here the bone is almost subcutaneous, being co- vered only by the common integument, some fibres of the platysma, and crossed by the supra-clavicular filaments from the cervical plexus of nerves. On the inferior surface of the clavicle we notice towards its sternal end a rough surface for the insertion of the costo-clavicular or rhom- boid ligament : external to this and extending outwards is a superficial excavation along the inferior surface of the bone, which lodges the subclavius muscle. This groove terminates at the commencement of the external fourth of the bone, where we notice a rough and promi- nent surface for the insertion of the coraco-cla- vicular or conoid and trapezoid ligaments; in the articulated skeleton this surface corresponds to the root of the coracoid process, immediately over which it lies. On the inferior surface, near its middle, is the orifice of the canal for the transmission of the nutritious artery, the direction of which is outwards. The anterior edge is thicker and more rounded towards the inner than towards the outer end, where it partakes of the general flattened ap- pearance of the bone at that part; in the former situation it affords attachment to the pectoralis major muscle — in the latter to the deltoid. The two internal thirds of this edge are convex, its external third is concave. The posterior edge is smooth and thin upon its two internal thirds, thicker and rougher at its external third, where the trapezius muscle is inserted into it; in the former situation this edge is convex, in the latter it is concave. The relations of the clavicle in this situation are in- teresting : it forms the anterior boundary of a space somewhat triangular in form, through which a communication is formed between the axilla and the neck. The posterior boundary of this opening is formed by the superior border of the scapula, and the internal by the inferior vertebra of the cervical region of the spine, while the first rib constitutes a sort of floor, over which pass the various vessels, nerves, and other parts which enter the cavity of the axilla. The anterior third of the first rib passes beneath the sternal end of the clavicle, but its two posterior thirds lie on a plane superior to it. Consequently we find that the cone of the pleura passes up behind this end of the clavicle so as to be on a level with it, hence the so- noriety elicited by percussion of the clavicle, and hence likewise the possibility in many instances, where embonpoint does not interfere, of hearing the respiratory murmur in the supra- clavicular region. The great importance of the clavicle in the motions of the upper extremity is rendered abundantly evident by observing how com- pletely synchronous are its movements with even the slightest change of position in the arm. But this is illustrated in a more striking man- ner by reference to the comparative anatomy of this bone. Those animals only possess a well- developed clavicle whose habits of life require extensive and varied movements of the shoul- der. Where the anterior extremity is employed merely as an instrument of progressive motion on a plane surface, we have no clavicle ; hence this bone is absent from the skeletons of Pa- chydermata, Ruminantia, Solipeda, and the mo- tions of the shoulders are only such as are required for the flexion and extension of the limb. In the Carnivora, where there is a slight increase in the range of motion of the anterior extremities, a rudimentary clavicle exists, and in this class we observe that the size of the bone in the different orders bears a direct relation to the extent of motion enjoyed by the limb. Thus it is smallest in the Dogs and largest in the Cats; in these animals it has no attachment to either the sternum or the scapula, but is enclosed in the flesh, and does not occupy much more than half the space between the two bones last named. " But, however imperfect," says Sir C. Bell, " it marks a correspondence in the bones of the shoulder to those of the arm and paw, and the extent of the motion enjoyed. When the bear stands up, we perceive, by his ungainly attitude and the motion of his paws, that there must be a wide difference in the bones of his upper extremity from those of the ruminant or solipede. He can take the keeper's hat from his head and hold it; he can hug an animal to death. The ant-bear especially, as he is defi- cient in teeth, possesses extraordinary powers of hugging with his great paws; and, although harmless in disposition, he can squeeze his enemy the jaguar to death. These actions and the power of climbing result from the structure of the shoulder, or from possessing a collar-bone however imperfect."* In those Mammalia that dig and burrow in the ground, or whose anterior extremities are so modified as to aid them in flight, or who are skilful in seizing upon and holding objects * Bridgcwatei Treatise, p. 48. 156 EXTREMITY. with their paws, the clavicle is fully developed, and extends the whole way from the scapula to the sternum. Thus in the Rodentia this bone is very perfect, as, for example, the Squirrel, the Beaver, the Rabbit, the Rat, &c. The Bat affords an example of a very strong and long clavicle, as also the Mole and the Hedgehog among the Insectivora. Among the Edentata those tribes possess a clavicle whose habits are fossorial, as the Ant- eater, the Armadillos, and even the Gigantic Megatherium, in which animal, however, the clavicle presented the peculiarity of being arti- culated with the first rib instead of with the sternum. In the Quadrumana the clavicles are strong and curved as in the human subject. In Birds, the bone which is analogous to the clavicle presents similar variations in its developement, according to the range of motion required in the anterior extremity, or in other words, in proportion to the extent to which the powers of flight are enjoyed. Thus, in some these bones are anchylosed along the mesial line, and constitute the furculum ; in others they are cartilaginous internally; and in others they do not reach the sternum.* In women the clavicle is in general less curved than in men ; the diminution in the incurvation is most manifest in the external portion. Accord- ing to Cruveilhier, the clavicles are often une- qually developed in the same individual accord- ing as one limb is more used than the other, and sometimes the difference is sufficiently obvious to enable one to ascertain from the relative size of the clavicles, whether the individual is right or left-handed. Structure. — The clavicle contains a conside- rable proportion of compact tissue in its shaft, and a cylindrical medullary canal ; at the ex- tremities the compact tissue greatly diminishes, and is replaced by the reticular, which likewise fills up the bone and obliterates the medullary cavity. Developement. — A strong argument as to the great importance of this bone to the motions of the shoulder, is derived from its precocious de- velopement ; for although the cartilaginous nidus of the vertebrae as well as that of the ribs appear before that of the clavicle, yet the latter bone begins to ossify sooner and is completed more rapidly than any other bone in the body, ex- cepting perhaps the lower jaw, which some- times takes the precedence in the process of ossification. It is remarkable too for the diver- sity in its proportional size, which it presents at different periods; thus, according to Meckel, about the middle of the second month of pregnancy, the clavicle is four times longer than the humerus or femur, and it is not until the fourth month that the humerus exceeds it in length. The clavicle has but one primitive point of ossification : a supplementary point is developed under the form of a very thin lamella at the anterior part of the sternal extremity .f Scapula, scapulum, omoplata, (wfto;, hume- rus, wXaru;, latus.) Fr. omoplate; Germ, das Schulterblatt. — This bone forms the posterior * See Avrs, p. 285, vol. i. t Cruveilhier, Anat. Desc. t. i. p. 219. and principal portion of the shoulder; it is placed on the posterior and outer part of the thorax, and occupies a space which extends from the second to the seventh rib. The scapula is very thin in the greatest part of its extent, quite papyraceous in some places. It is triangular in form, and anatomists com- monly describe its sides or borders, its angles, and its surfaces. The borders, or costa, of the scapula are three in number, and are named according to the position they occupy or the relation they bear: thus there are the superior border or cervical, the posterior or vertebral, and the anterior or axillary. The cervical border (also called the coracoid ) is the shortest, being some- what less than a fourth of the length of the vertebral border; it is connected posteriorly with the vertebral at an angle the apex of which is rounded off; it is slightly concave,and the bone for some way below it is very thin, and the bor- der itself is acute. Anteriorly it terminates in a notch which is bounded in front by one root of the coracoid process, ( incisura semilunaris, lunula, coracoid notch.) This notch is converted into a foramen by a ligament which is often ossi- fied, and thus the suprascapular nerve, which is lodged in the notch, is separated from the artery of the same name, which passes over the ligament. The extent, therefore, of the cervical border is from the posterior superior angle to this notch. The levator anguli sca- pulae and the omo-hyoid muscles are attached to this border. The vertebral border, also called the base of the scapula, is the longest, being in an ave- rage-sized bone from seven to eight inches in length ; it is sharp in its whole extent, which is limited above by the posterior superior angle, and below by the inferior angle. At the junc- tion of the superior fourth with the remaining portion there is an inclined surface, triangular in form, the base confounded with the margin of the bone, the apex continued to the spine. This surface is smooth, and the ascending fibres of the trapezius muscle glide over it. To that part of this edge, which is above the surface, the levator anguli scapulae is attached, and below it the rhomboidei. The anterior or axillary border is limited above by the glenoid cavity, and below by the inferior angle of the scapula. It is much thicker than either of the others, and its thick- ness increases towards its upper extremity, where, close to the glenoid cavity, there is a rough surface which gives attachment to the long head of the triceps muscle ; inferior to this, the edge affords insertion to the teres minor muscle, and still lower down to the teres major. The superior and posterior angle is formed by the junction of the cervical and vertebral bor- ders; it is a little less than a right angle, and is chiefly remarkable for affording insertion to the levator anguli scapula; muscle. The inferior angle, formed by the union of the axillary and vertebral borders, is very acute; the bone here is very thick and spongy ; part of the latissimus dorsi glides over this angle, and sometimes some of its fibres are inserted into it. It is EXTREMITY. 157 only this portion of the muscle which separates this part of the scapula from the common inte- guments, and to this superficial position is at- tributed the more frequent occurrence of frac- tures from direct violence in this than in any other portion of the bone. The angle between the cervical and axillary borders is truncated, and presents many points of great interest. We here notice an articular concavity, destined to contribute to the for- mation of the shoulder-joint, commonly known under the name of the glenoid cavity, (sinus articularis.J This cavity, which is a very superficial one, is oval ; the long axis of the oval being vertical in its direction, the acute extremity of the oval is situated superiorly, and here the edge of the bone is cut and rounded off towards the posterior part, where is inserted the tendon of the biceps. The cavity is surrounded by a thick lip of bone, to which in the recent state the fibre-cartilage, called glenoid ligament, is applied. At the internal or anterior part of this border, is a notch for the passage of the tendon of the sub- scapularis muscle. The aspect of the glenoid cavity when the scapula is quiescent is outwards and slightly upwards and forwards. This cavity is connected with the rest of the bone by a thick but contracted portion denominated the neck of the scapula. The neck of the scapula is surmounted by a remarkable curved process, called the coracoid process, (xopaf, corvus.) This process, well compared to a semiflexed finger, is directed forwards and outwards, it is connected to the scapula by a thick portion, which seems to arise by two roots, one posterior, thick and rough, lying immediately in front of the notch in the cervical border, the other anterior and thin, and connected with the apex of the glenoid cavity. The concave surface of the coracoid process is directed downwards and outwards, and in the recent state projects over the upper and internal part of the shoul- der-joint: its convex surface is rough, and has inserted into it the ligaments by which the clavicle is tied to it. The coracoid process affords attachment by its internal edge to the pectoralis minor muscle ; to its outer edge is affixed the ligament which, with the acromion process, completes the osseo-ligamentous arch over the shoulder-joint, and by its summit it gives insertion to the short head of the biceps and to the coraco-brachialis. It remains only to examine the surfaces of this bone. The anterior surface forms in the greatest part of its extent a shallow fossa, fossa subscapularis, which is limited above and be- hind by the superior and posterior margins of the bone, and in front by a smooth and rounded ridge, which extends from the glenoid cavity to the inferior angle. This fossa is frequently intersected in various directions by bony ridges. Cruveilhier remarks, that in a well-formed per- son, this surface ought to be exactly adapted to the thorax; but when the chest is contracted, as in phthisical patients, the scapula not par- ticipating to a proportionate extent in the con- traction, there follows such a change of re- lation that the scapula; become very prominent behind, and are in some degree detached from the ribs like wings, whence the expression scapula alata, applied to the projection of the shoulders in phthisical patients. The whole fossa has lodged in and inserted into it the subscapularis muscle, whence its name. At the superior posterior angle and the inferior one, are rough surfaces into which are inserted the superior and inferior fibres of the serratus magnus muscle. The posterior surface is remarkable for its- division into two portions by a large process which projects from it nearly horizontally back- wards and slightly upwards. This process, called the spine of the scapula, is fixed to the bone at the line of union of its superior and mid- dle thirds ; it commences at the triangular surface already noticed at the termination of the superior fourth of the vertebral border of the scapula, thence it proceeds outwards, in- clining a little upwards, and just where the neck of the scapula is united with the rest of the bone, this spine ceases to be connected with the scapula, and is continued outwards in a slightly arched form, as a broad and flattened process, denominated the acromion process, (ax^o;, summus, w|ao{, humerus.) The spine presents posteriorly a thick and rough edge, which by its superior border gives attachment to the trapezius muscle, and by its inferior to the deltoid, the intervening space being covered by the aponeurotic expansion which connects the muscles last-named. The superior surface of the spine looks nearly directly upwards; it is concave, and contributes to form the fossa supra-spinata. The inferior surface, on the other hand, forming part of the fossa supra- spinata, is convex anteriorly and slightly con- cave posteriorly, and looks downwards and backwards ; on each surface we observe a large nutritious foramen. The posterior edge of the spine is quite subcutaneous, and the physician often finds it desirable to practise percussion upon it. Above the spine of the scapula is the fossa supra-spinata, which lodges the muscle of the same name, formed in front by the scapula, behind by the spine, both surfaces being slightly concave. Below the spine is the fossa supra-spinata much larger than the preceding, slightly convex, except towards its anterior part. This fossa is formed by the scapula below and the inferior surface of the spine above ; it is limited in front by a ridge which proceeds downwards and backwards, from the glenoid cavity to the inferior angle, and bounds behind a surface which gives attachment to the teres major and minor muscles. Into this ridge itself is inserted a fibrous fascia, which separates the attachment of the last-named muscles from the fossa infra-spinata and the insertion of the muscle of the same name. The two fossae, thus separated by the spine, com- municate through a channel formed on the posterior part of the neck of the scapula and bounded behind by the spine ; through tin's channel pass the arterial and nervous ramifica- tions from the superior to the inferior fossa. The acromion process is evidently continu- 158 EXTREMITY. ous with the posterior thick edge of the spine of the scapula, and viewed from above ap- pears to be merely an expansion of it. The narrowest part of the process is where it seems to spring from the spine, forming a sort of pedicle. Its posterior surface is convex, rough, covered with fibrous tissue in the recent state ; its aspect is upwards and backwards. Here the process is quite subcutaneous as the pos- terior part of the spine of the scapula. The anterior surface is concave, smooth, looks downwards and forwards to the posterior and superior part of the shoulder-joint. The posterior or inferior edge of the process con- tinuous with the corresponding edge of the spine of the scapula forms a curve, convex downwards and outwards, and terminates in the pointed extremity or apex of the pro- cess ; all this edge affords attachment to the deltoid muscle. The superior edge is con- cave ; near the apex we observe upon it a plane oval articular surface to which the acromial extremity of the clavicle is articulated ; into this edge the trapezius muscle is inserted. The apex of the acromion, which is imme- diately in front of the articular surface for the clavicle, gives insertion to the apex of the liga- ment, whose base is attached to the outer edge of the coracoid process. The scapula is connected to the trunk through its articulation with the clavicle, but chiefly through the intervention of muscles, so that muscles are inserted into all its edges, and its surfaces are " cushioned with muscles." It is, then, as might be anticipated, a very moveable bone, and its motions consist in more or less extensive revolutions round an axis through its centre. This bone, then, being the medium of connexion between the pectoral extremity and the trunk, it is evident that the great move- ments of the former must depend upon the movements produced in the scapula by the muscles which pass to it from the trunk ; more- over, when some of these muscles fix the scapula, it becomes the point whence the others act in producing the motions of the ribs. The scapula, then, is an essential element in the upper extremity, and it exists wherever we find that limb in a perfectly developed state, but it experiences various modifications in position and shape according to the uses to which the upper extremity is applied. In quadrupeds the position of the scapula is more forwards and on the side of the chest, for in them the anterior extremity is employed as an instrument of support. It is interesting to observe the variation in the aspect of the glenoid cavity, according to the oblique or upright position of the scapula, indicating whether the pectoral extremities are used chiefly as instruments of support or as instruments of prehension, Stc. When freedom and rapidity of motion are required conjoined with strength, we find the scapula placed obliquely over the ribs, and a corresponding obliquity between the humerus and scapula. " In the horse, as in most quadrupeds, the speed results from the strength of the loins and hinder extremities, for it is the muscles there which propel the animal. But were the anterior extremities joined to the trunk firmly and by bone, they could not withstand the shock from the descent of the whole weight thrown forwards ; even though they were as powerful as the posterior extremities they would suffer fracture or dis- location. We cannot but admire, therefore, the provision in all quadrupeds whose speed is great, and whose spring is extensive, that, from the structure of their bones, they have an elastic resistance by which the shock of descend- ing is diminished. " If we observe the bones of the anterior extremity in the horse, we shall see that the scapula is oblique to the chest, the humerus oblique to the scapula, and the bones of the fore-arm at an angle with the humerus. Were these bones connected together in a straight line, end to end, the shock of alighting would be conveyed through a solid column, and the bones of the foot or the joints would suffer from the concussion. When the rider is thrown forwards on his hands, and more certainly when he is pitched on his shoulder, the collar-bone is broken, because in man this bone forms a link of connexion between the shoulder and the trunk, so as to receive the whole shock; and the same would happen in the horse, the stag, and all quadrupeds of great strength and swiftness, were not the scapula sustained by muscles and not by bone, and did not the bones recoil and fold up." " The horse-jockey runs his hand down the horse's neck in a knowing way and says, ' this horse has got a heavy shoulder, he is a slow horse.' He is right, but he does not under- stand the matter; it is not possible that the shoulder can be too much loaded with muscle, for muscle is the source of motion and bestows power. What the jockey feels and forms his judgement on is the abrupt transition from the neck to the shoulder, which, in a horse for the turf, ought to be a smooth undulating surface. This abruptness or prominence of the shoulder is a consequence of the upright position of the scapula; the sloping and light shoulder results from its obliquity. An upright shoulder is the mark of a stumbling horse — it does not revolve easily to throw forward the foot."* A comparison between the skeleton of the anterior extremity in the elephant and in one of the stag kind illustrates how the oblique position of the scapula is favourable to rapidity of motion, while the upright position is that most calculated for supporting weight. In the elephant the glenoid cavity of the scapula is placed vertically over the head of the humerus, and all the other component parts of the limb are similarly disposed, so as to form a complete pillar of support for the trunk. Hence the attitude of standing in the elephant requires but slight muscular effort, and in this position he is in such complete repose as often to obtain sleep. In this animal, then, the angle between the scapula and humerus is nearly obliterated, but in the stag it approaches closely to a right angle, the scapula is oblique to the ribs, and * Sir Charles Bell, Bridgewater Treatise*' EXTREMITY. 159 the humerus to the scapula. The rule seems to be that where the pectoral extremity is chiefly a pillar of support, the aspect of the glenoid cavity is nearly vertically downwards. If free- dom and rapidity of motion be required in addition to strength as a member of support, the trunk being lighter, the scapula is oblique, and consequently the glenoid cavity looks downwards and forwards ; or if the limb be not used to support the trunk, then the aspect of the glenoid cavity is no longer downwards but outwards, as in man. Structure. — The greatest part of the scapula is composed of very thin almost papyraceous compact substance ; but its processes, and the enlargements at its edges and angles, contain reticular tissue. Developement. — This bone is developed by six points of ossification ; one for the body, and five supplementary ones, viz. one for the coracoid process, two for the acromion, one for the posterior border of the bone, and one for its inferior angle. The ossification of the body commences about the second month, and the spine appears in the third month as a growth from the posterior surface of the scapula. The union of the several epiphyses is not completed till late, and it is not until after the fifteenth year that the ossification is finished. The bones of the upper extremity, properly so called, are the humerus, radius, ulna, and bones of the hand. Humerus, (os brachii ; Fr. Vos du bras; Germ, das Oberarmbein ). This is the longest bone of the upper extremity; it is situated between the scapula and forearm, being, as it were, suspended by muscle and ligament from the former. Like all long bones, the humerus consists of a shaft and two extremities. The superior extremity is formed by a smooth and rounded convexity, rather less than half a sphere ; a slight depression in, or constriction of, the bone, most manifest above, marks the limit of this articular eminence. The eminence is called the head of the humerus ; the constric- tion indicates what is denominated the anato- mical neck of the bone, being that portion which connects the head to the shaft, and analogous to the more developed neck of the thigh-bone. The axis of the neck is but a continuation of that of the head, and passes in a direction from within outwards and down- wards, forming an obtuse angle with the axis of the shaft. The head of the humerus is entirely covered by articular cartilage, and arti- culates with the glenoid cavity of the scapula, to which, however, it obviously does not at all correspond in dimensions. The inferior part of the anatomical neck of the humerus is very slightly marked, and is continued in a smooth declivity slightly con- cave from above downwards, into the shaft of the bone. Its superior part is more distinct, and the depth of the groove here seems in a great degree owing to the prominence of two bony protuberances, one situated anteriorly, called the lesser tuberosity, and the other pos- teriorly, denominated the greater tuberosity. The lesser tuberosity of the humerus ( tuber- culum minus ) is somewhat conical in shape, and inferiorly it ends in a smooth, rounded bony ridge (spina tuberculi minoris ), which extends downwards and inwards, gradually diminishing in prominence till it is lost in the shaft of the bone at the inner part of its ante- rior surface. The lesser tuberosity gives in- sertion to the tendon of the subscapulars muscle, and the ridge or spine last described forms the anterior and internal boundary of the bicipital groove. The greater tuberosity (tuberculum majus, externum s. posterius ) forms a considerable prominence on the upper and outer part of the humerus, being the most external part in that situation and easily to be felt under the integuments. Superiorly the constriction cor- responding to the anatomical neck separates it from the head of the humerus ; inferiorly it is continued into and gradually lost in the shaft of the bone at its outer part. A very distinct and prominent ridge ( spina tuberculi majoris) is continued from its anterior extremity down- wards and inclining very slightly inwards, which terminates about the middle of the an- terior surface of the bone, just internal to the deltoid ridge. This ridge is most prominent but smooth in its upper third, in its inferior two-thirds it is less prominent but rough ; it forms the posterior boundary of the bicipital groove. On the greater tuberosity three dis- tinct surfaces are marked, to the anterior of which the supra-spinatus muscle is attached, to the middle the infra-spinatus, and to the posterior the teres minor. The bicipital groove commences above be- tween the two tuberosities, and passes down- wards and slightly inwards, bounded before and behind by the spines which proceed from those tubercles. This groove, very distinct at its commencement, ceases to be so a little above the termination of the superior third ; in the recent state it is lined by the tendinous expansion of the latissimus dorsi and teres major muscles, and lodges the tendon of the biceps muscle, whence its name. From the anatomical neck the bone gra- dually tapers down and becomes more cylin- drical in its form ; this upper portion is, for the convenience of description, distinguished by the name of surgical neck of the humerus. The middle third of the shaft of the bone is prismatic in form ; the external spine whicli commences at the greater tuberosity is continued down, forming a prominent ridge all down the front of the bone to the termination of its flattened inferior third. The outer part of the middle third of the humerus is remarkable for the rough surface into which the deltoid muscle is inserted, the deltoid ridge, situated nearer the upper than the lower part of this portion, and directed downwards and very slightly forwards. The inner part of the middle third presents a smooth, flattened, and inclined surface, which is continued down in this form to within a very short distance of the inferior extremity of the bone. The posterior surface is rounded and very smooth. 160 EXTREMITY. At the junction of the middle and inferior thirds we notice a very slight and superficial groove passing downwards and inwards, and very much resembling what one would ima- gine might be produced by an attempt to twist the bone while yet in a yielding condition, the inferior third having been twisted inwards and the two superior thirds outwards. This groove indicates the spiral course from above down- wards and from without inwards of the musculo- spiral or radial nerve. Below this groove is the inferior third of the humerus, the anatomical characters of which are very distinct from those of the remaining parts of the bone. A pro- minent and rounded ridge, continuous with that already noticed in connexion with the greater tuberosity, passes vertically down in front of it; from each side of this ridge a smooth surface inclines backwards, forming an inclined plane on each side of it, the ex- ternal being larger and more distinct than the internal. The posterior surface of the upper part of this portion is flat and very smooth. As the bone descends it expands considerably late- rally, so as to present in front a broad surface slightly convex from side to side, bounded on either side by prominent edges, continued from the edges of the inclined planes above de- scribed. Each edge terminates in a pro- minence, the inner one being the largest ; the inner edge itself being thicker, more pro- minent, and describing a slight curve as it descends. The posterior surface is limited below by a deep depression, to be further de- scribed hereafter. Thus, by its gradual expan- sion laterally, the inferior portion of the hu- merus, being about one fifth of the entire length of the bone, has a triangular figure, the base being formed by the inferior articular ex- tremity of the bone. The whole shaft of the humerus is com- pletely clothed with muscle. We have already indicated the place of insertion of the deltoid muscle on the outer surface of the bone ; all that portion of the outer and anterior surface below the deltoid ridge, and for a little way on each side of its inferior extremity, is co- vered by the brachiaeus anticus muscle. In- ternal to the bicipital groove, on the inner surface of the humerus, about its middle, the coraco-brachialis muscle is inserted. The ex- ternal edge below the spiral groove affords attachment to the brachials anticus, supinator longus, extensor carpi radialis longior, and the triceps muscles. The internal edge below the insertion of the coraco-brachialis has the brachiaus anticus and triceps muscles inserted into it, and both edges afford insertion to intermuscular apo- neuroses, which separate the muscles con- nected with the anterior from those on the posterior part of the bone. The posterior sur- face is completely covered by the triceps mus- cle, excepting in the line which corresponds to the groove already referred to, in which the radial nerve and musculo-spiral artery pass. The foramen for the nutritious artery is found upon the internal surface at the inferior ex- tremity of its middle third ; the direction of the canal is downwards ; sometimes this fora- men exists upon' the external, or upon the in- ternal surface. The inferior extremity of the humerus is terminated by an articular cylinder, which pro- jects into a plane anterior to that of the shaft of the bone, (processus cubitalis ). This cy- linder is placed transversely, but in transverse extent it falls short of the widest part of the inferior third of the humerus. Various de- pressions and elevations are marked upon the surface of this cylinder. Proceeding from without inwards, we notice a convexity or rounded head, limited externally by the mar- gin of the cylinder and internally by a groove, which passes in a curved direction from before backwards, the concavity of the curve corres- ponding to the rounded head. This head is properly denominated the external condyle of the humerus ; it articulates with a cavity on the head of the radius ; the anatomist should notice that the axis of this head passes in a direction downwards and forwards. On the anterior surface of the humerus immediately above this head, we observe a slight and very superficial depression which receives the edge or lip of the cavity of the radius, when the forearm is in a state of complete flexion. Internal to the groove which bounds the con- dyle on the inner side, we have a pulley-like surface, which is destined for articulation with the ulna. The concavity which forms the cen- tral part of this pulley is deep, but deeper and wider behind than before; its anterior ex- tremity terminates in communicating with an oval depression on the anterior surface of the bone (fovea anterior minor), which in flexion of the forearm receives the anterior projecting angle of the coronoid process of the ulna ; the posterior extremity terminates in a similar depression, (fovea posterior v. sinus maximus,) but a much deeper one, and of greater dimen- sions generally, occupying, in short, nearly the whole posterior surface of the bone; this de- pression receives the olecranon process of the ulna, when the elbow-joint is in extension. The trochlear concavity, in passing from before backwards, takes a curved direction, so that its posterior extremity is much nearer the external part of the articular cylinder than the anterior. This has an important influence on the direc- tion of the motions of the forearm. These two depressions are separated from each other by a thin osseous lamina, almost transparent. We sometimes meet with instances in which this lamina is perforated in consequence of a defect of ossification ; and Meckel states that he has found this perforation more frequently in the bones of Negroes and Papuas than in those of the superior races of mankind. It is the permanent condition of many pachydermata, rodentia, carnivora, and quadrumana. On the inside the trochlear concavity is bounded by a thick and projecting lip, which, when the bone is placed at right angles with a horizontal plane surface, descends lower down than any other part, so that this part comes in contact with the plane surface, while the remaining EXTREMITY. portion of the articular cylinder is raised con- siderably above it. This arrangement accounts for the hollow angle manifest on the outer side of the elbow-joint when the forearm is extended. We have yet to describe two processes which are connected in great measure with the outer and inner extremities of the articular cy- linder, and to which we have already referred, as being the points in which the margins of the bone terminate. The external one is trian- gular and thick, rough upon its surface, and projects slightly. It is improperly called the external condyle — more correctly it should be designated epicondi/le, being applied to the outer surface of what is properly the external condyle. This process affords attachment to the external lateral ligament of the elbow- joint and to the principal supinator and ex- tensor muscles on the forearm, whence it has been called condylus extensorius. The inter- nal process is very prominent, distinctly trian- gular, terminating the inner edge of the hu- merus and connected with the trochlea; it is more correctly denominated epitrochlea. It affords insertion to the internal lateral ligament, and to the pronator and flexor muscles of the forearm. Its posterior surface is slightly hol- lowed at the line of its junction with the rest of the bone ; the ulnar nerve passes behind it. The humerus is the principal lever of the pectoral extremity ; hence in all animals its strength is proportionate to the force and power which is required in the limb. In the ele- phant it is a massive pillar of support; and here we may notice a variety following the same law which influences the difference in the aspect of the glenoid cavity of the scapula, already noticed ; namely, that the angle be- tween the axes of the head and shaft of the humerus, is at its maximum when the arm- bone is mainly an instrument of support, and diminishes as that bone is more used for pre- hension and other purposes ; and as this use is found for this bone chiefly in the human sub- ject, we may presume that in man the angle in question is the least removed from a right angle. When this limb is used mainly for support and progression, a considerable range of motion in the shoulder-joint is not required, the tuberosities at the upper extremity of the bone project and limit the motions of the joint. When, however, a considerable motion is ne- cessary,these tubercles are depressed as in man, so as not to interfere with these motions. The lower extremity of the humerus likewise affords marks indicative of the mobility of the fore- arm and hand ; thus, in the one case one or both of the edges of the bone which terminate in the epitrochlea and epicondyle are promi- nent and strong in proportion as the muscles which arise from it are frequently called into play, as when the pronating and supinating motions of the forearm are extensive : in the other case this ridge is imperfectly developed, and the principal modification of the lower end of the bone is to be seen in the articular cy- linder, where greater depth is given to the trochlea, in order to afford increased strength and security to the elbow-joint. VOL. II. One of the most singular instances of the developement of bony processes in accordance with muscular power is in the case of the mole. In this little animal the whole anterior ex- tremity is constructed entirely with reference to its burrowing habits; its short, thick, and almost square clavicle and its elongated lever- like scapula tend to the same end, as its amaz- ingly strong humerus. The upper extremity of this latter bone is extremely broad ; it pre- sents two articular surfaces, being articulated with the clavicle as well as with the scapula, and the tuberosities which give insertion to the muscles of rotation are enormously de- veloped. The body of the bone is short, thick, and strong; the inferior extremity is nearly as large as the superior ; both the epicondyle and epitrochlea are very highly developed, especially the latter, which is accounted for by the fact that the muscles of pronation are those most called into action, in order to enable the animal to employ the accessory bone on the radial side of the hand, in scraping up the earth. This large size of the humerus, and great develope- ment of its muscular eminences, is found in all fossorial animals, as the megatherium, the pan- golins, beavers, ant-eaters, moles, and mono- tremata. In the two last the developement is the most remarkable. In the class of Birds, the humerus is de- veloped as regards the prominence of its mus- cular protuberances, in proportion to the powers of flight. In birds which fly, those eminences are strong and prominent, and the bone itself is proportionally strong; but in those which do not fly, the bone is weak and gene- rally short. In the common pigeon, for ex- ample, the enlargement of the scapular ex- tremity of the humerus, and the developement of the tubercles is very manifest, as well as the strength and thickness of the shaft of the bone. Structure. — The structure of the humerus is characteristic of that of long bones in general. In a vertical section we observe that the re- ticular texture is chiefly accumulated towards the extremities; the shaft being mainly formed of compact tissue. At the upper extremity we notice the mark of union of the epiphysis of the head, which corresponds to the line of the anatomical neck of the bone. The canal, when a transverse section of it is viewed, appears somewhat quadrilateral in form. Its walls are formed of very dense compact tissue. Developement. — The ossification of the hu- merus begins in its shaft, and that very early, according to Meckel about the second month ; the shaft goes on enlarging, but the extremities are still cartilaginous during the whole of in- tra-uterine life, and for the first year after birth. The superior extremity is developed by two points of ossification, one for the head, the other for the great tuberosity ; about the be- ginning of the second year the ossification of the head of the bone commences, and from the four-and-twentieth to the thirtieth month the ossification of the great tuberosity begins. According to Beclard, a small ossific point for the lesser tuberosity is visible in the fifth or M 162 EXTREMITY. sixth year ; from the eighth to the ninth year the ossifie elements of the head of the hume- rus become united and the head is com- pleted. The inferior extremity of the humerus, accord- ing to Cruveilhier, begins to ossify later than the superior. The first point of ossification noticed in it is for the external condyle: this appears at the age of two years and a half ; at seven years a second point of ossification commences for the epitrochlea; at twelve a third point appears for the internal edge of the trochlea; and at sixteen years a fourth point for the epicondyle. These four points of ossification, Cruveilhier states, are united in the following order: first, in the second year, the two points of the trochlea are united ; and, secondly, at sixteen years the trochlea, epicondyle, and the condyle form a a single piece.* The union of the extremities with the shaft of the bone takes place from the eighteenth to the twentieth year; and all ob- servers agree in stating that the union of the inferior extremity with the shaft always pre- cedes that of the superior extremity, although the ossification of the latter is prior. Forearm. — The bones of the forearm are the ulna and radius, of which the former con- stitutes the second essential element in the elbow-joint, the radius being chiefly an acces- sory bone to provide for the wider range of motion of the hand. The ulna therefore is the principal lever of the forearm, and the motions of flexion and extension of that segment of the limb upon the arm depend upon it ; at its superior extremity it forms a very firm hinge- jomt with the trochlea of the humerus, but in- feriorly its connexion with the carpus at the wrist-joint is very slight, and it forms by no means an essential element of that joint. On the other hand, the radius at its inferior ex- tremity forms a very important part of the wrist-joint, but at its superior its connection with the elbow-joint is due to its necessary articulation with the outer side of the ulna. Vina (KV@nov, cubitus; Fr. os du coitde ; Germ, das Elleribogenbein.f) This bone is situated on the inner side of the forearm. It is the longest and the largest bone of that region, and in the vertical position of the limb it is directed downwards and a little outwards, the obliquity being occasioned by the greater pro- jection downwards of the inner lip of the trochlea of the humerus, as already alluded to in describing that bone. The upper or humeral extremity of the ulna is at once distinguished by its great size from the inferior extremity. It consists of two pro- cesses joined to each other at a right angle, and so that that angle opens forwards. One of these processes is vertical, and is continued in * Cruveilhier, Anat. Descr. torn. i. p. 231. t The term focile was applied to this bone as well as to the radius by some of the ancient anatomists, in imitation of the Arabians, who used the word send, sc. an instrument analogous to our tinder-box, which consisted of two sticks, similar in appear- ance and proportions to the bones of the forearm. Focile majw was the ulna, focile minus the radius. Blumenbach, Beschreibung der Knochen, p. 395. the direction of the long axis of the bone, and is little else than a continuation of the shaft ; this is the olecranon: the other is horizontal, anterior to the olecranon, as it were placed upon the superior extremity of the bone, so as to project considerably beyond the plane of its anterior surface : this is the coronoid process. The olecranon, (wXehi, cubitus, k^oivov, caput,") also called processus anconeus, may be said to begin from the angle of junction of the coro- noid process with it ; there the bone appears slightly constricted, for above that point it ex- pands. We notice five surfaces upon it. The superior surface is horizontal ; it presents pos- teriorly a muscular impression affording inser- tion to the triceps extensor, and anteriorly it ends in a remarkable beak, which, in the state of complete extension, is received into the ole- cranon cavity of the humerus. The posterior surface is rough with a very obviously trian- gular outline ; this surface gives insertion to the triceps muscle. The internal surface is also rough, and covered by the fibrous ex- pansion from the tendon of the triceps, and at its anterior margin affords insertion to the superior fibres of the internal lateral ligament. The external surface is smooth, and also is covered by the fibrous expansion from the ten- don of the triceps. The anterior surface is articular ; it presents the appearance of having been covered by articular cartilage ; it is divided by a rounded vertical ridge into two unequal portions, of which the internal is larger than the external. This surface is limited below by a transverse depression, non-articular, in which some fatty matter is deposited in the recent state. The surface is convex from side to side in the centre, and each of its lateral portions is concave ; the whole surface is concave from above downwards. In the extended state of the forearm this articular surface of the olecra- non is applied to the posterior part of the trochlea of the humerus ; it forms the posterior part of the great sigmoid cavity of the ulna. The coronoid process is wedge-shaped, at- tached by its base to the anterior surface of the ulna, the sharper edge projecting forwards and free. This edge is convex, and sometimes forms a point ; it is received into the coronoid cavity of the humerus. On the external sur- face of the coronoid process is an oval articular facet, concave from behind forwards, whose long axis is horizontal ; this is the lesser sigmoid cavity, and is articulated with the inner side of the head of the radius ; the internal surface is rough, and has a projecting lip, which affords attachment to the anterior fibres of the internal lateral ligament. The anterior surface is in- clined from above downwards and from before backwards, so that its aspect is downwards and forwards ; it is slightly hollowed transversely, and is rough, the roughness being continued down for a little way in front of the bone, thus forming a rough surface triangular in form, the base corresponding to the anterior edge of the coronoid process ; this surface affords insertion to the brachiaeus anticus muscle. The superior surface forms the anterior portion of the great EXTREMITY. 163 sigmoid cavity; like the similar surface on the olecranon, it is divided by an obtuse ridge directed from before backwards, into two une- qual portions ; these portions correspond in shape and size with those already noticed on the olecranon. The shaft of the ulna gradually tapers from above downwards ; it is triangular in its entire extent, excepting for about an inch above the inferior extremity, where the bone is distinctly cylindrical. On the shaft anatomists commonly describe three surfaces. The anterior surface is broader in the middle than at its extremities; it is slightly concave in the transverse direction in its middle third ; on this surface, at its upper part, we notice the orifice of the nutritious canal, which is directed upwards towards the coro- noid and olecranon. By its three superior fourths this surface affords attachments to the flexor digitorum profundus, and by its inferior fourth to the pronator quadratus; the place of attachment of this latter muscle is limited above by an oblique line which passes from without inwards and from above downwards. The in- ternal surface is smooth, and convex in its en- tire extent; widest above, it gradually tapers to the inferior extremity. In its inferior fourth it is subcutaneous, and to its three superior fourths is attached the deep flexor muscle of the fingers ; the aspect of this surface is back- wards as well as inwards. The third surface is posterior. The two in- ferior thirds of this surface are smooth, the mid- dle being flat and the lowest rounded ; here are attached the extensor muscles of the thumb and that of the index finger. In the superior third we distinctly notice two surfaces, easily distinguishable by the difference of aspect ; the internal one, which is continued up on the olecranon process, looks backwards and slightly outwards; to it the anconaeus muscle is attached superiorly, and inferiorly the extensor carpi ulnaris. The external of these two surfaces looks directly outwards, and is separated from that last described by a line which passes ob- liquely downwards and inwards ; to this sur- face, which commences just below the lesser sigmoid cavity, the supinator brevis is attached, and below it, commences the line of attachment of the extensor muscles already alluded to. Three edges separate the surfaces above de- scribed ; of these the external is at once distin- guished by its greater prominence ; it is sharp in nearly its two inferior thirds, and superiorly is lost on the surface to which the supinator brevis is attached ; all that part of this edge which is prominent and sharp gives insertion to the interosseous ligament. The anterior edge commences just below the coronoid pro- cess, and terminates, inclining a little back- wards, in front of the styloid process of the ulna : it is rounded and smooth in its entire extent, and has the deep flexor of the fingers and the pronator quadratus inserted into it. The posterior edge commences at the apex of the posterior surface of the olecranon, and ter- minates insensibly towards the inferior fourth of the bone. The inferior or carpal extremity of the ulna is very small; it forms a slightly rounded head ; on its posterior and internal part is a small process, projecting vertically downwards and ending in a point, to which the internal lateral ligament of' the wrist-joint is attached : this process is the styloid process ; external to this is a depression or pit, into which is inserted the triangular cartilage of the wrist-joint, and external to this depression is the rounded head, which is smooth on its inferior surface, covered with cartilage in the recent state ; the triangular cartilage glides upon this surface. On the outer side of the head is an articular convexity which articulates with a concave surface on the inner side of the carpal extremity of the radius. On the posterior surface of the head, imme- diately external to the styloid process, there is a slight channel, in which is lodged the tendon of the extensor carpi ulnaris. Structure. — The olecranon and coronoid processes are completely cellular in structure, excepting the external cortex of compact tissue. The inferior extremity of the ulna is likewise cellular, but the shaft is mainly composed of compact tissue, hollowed by a medullary canal, which commences a little below the coronoid process, and terminates just above the inferior extremity. liadius, (Germ, die Speiche,) so called from its being compared to the spoke of a wheel ; it is the shorter of the two bones of the forearm ; its proportion to the ulna being as 11 to 12. The superior extremity or head of the radius is a cylindrical head excavated on its superior surface so as to form a superficial cavity, cuvitas glenoidea, which is articulated with the external condyle of the humerus. The circumference of this head consists of a deep lip of bone present- ing a smooth surface covered by cartilage in the recent state, the depth of which, measured verti- cally, is greatest on the inner side, so as there to form an oval convex articular facet which is adapted to the lesser sigmoid cavity of the ulna ; the remainder of the circumference is embraced by the annular ligament of the radius. The head of the radius is connected to the shaft by a short and cylindrical neck, which passes obliquely downwards and inwards; the neck of the radius is limited inferiorly and on the ulnar side by a rounded tubercular process, into the internal posterior and rough partof which the biceps mus- cle is inserted, the bicipital tuberosity or tubercle of the radius; the anterior part of this tubercle, over which the tendon of the biceps glides, is smooth. For about an inch below this process the bone retains the cylindrical form, being here embraced by the inferior fibres of the su- pinator brevis muscle; but below this the bone becomes distinctly prismatic in its form, and begins to expand to its inferior or carpal extre- mity. We here describe three surfaces as in the ulna : the anterior is inclined inwards, its aspect is forwards and inwards ; about its middle this surface is slightly hollowed from above downwards; at the junction of its middle and inferior third it is convex, and in its inferior third, where it attains its greatest lateral expan- sion, it is concave again. At the superior third of the bone we notice on this surface the nutri- 164 EXTREMITY. tious foramen, the canal following the same direction as that of the ulna, namely upwards. The muscles attached to the anterior surface of the radius are the flexor pollicis proprius, con- nected with the two superior thirds of the bone, and the pronator quadratus occupying the in- ferior third. The posterior surface of the radius is likewise inclined, and looks backwards and inwards, very narrow in its whole extent, but broadest at its inferior extremity, convex in its superior and inferior thirds, and slightly con- cave from above downwards in its middle third. This last portion of the bone affords attachment to the two inferior extensor muscles of the thumb ; the superior third is embraced by the supinator brevis, and the inferior third has applied to it the tendon of the common extensor of the fingers, the indicator, and the extensor tertii internodii pollicis. The external surface is convex in its whole extent, and like the others expands inferiorly; about its middle we observe a rough surface, which gives insertion to the pronator quadratus ; in its upper portion the surface is embraced by the supinator brevis, and inferiorly the radial extensors of the wrist are applied to it. Of the three edges which separate these sur- faces, the internal is sharp, and extends from about an inch below the bicipital tuberosity to about the same distance above the carpal extre- mity of the radius; at this latter point the edge seems to bifurcate and form a plane triangular surface above the inferior extremity of the ra- dius. This edge gives attachment in its entire extent to the interosseous ligament. The an- terior edge is rounded ; it distinctly originates from the bicipital tuberosity, and terminates at the outer side of the carpal extremity of the radius in front of the styloid process. The su- pinator brevis, the proper flexor of the thumb, and the flexor sublimis of the fingers, have attachments to this edge above, and below the pronator quadratus and supinator longus are inserted into it. The posterior edge is very imperfectly defined, being distinct only in its middle. The inferior or carpal extremity of the radius is the largest part of the bone ; it is irregularly quadrilateral in form. Its inferior surface forms an articular excavation, the outline of which is triangular, the apex being external and the base internal ; this surface is divided into two by a slightly prominent line which passes from before backwards ; the outer of these two portions retains the triangular form, and is articulated with the scaphoid bone of the carpus ; the internal is quadrilateral, and articulated with the lunar bone. At its inner margin, this surface is continuous with a slightly excavated articular facet on the ulnar side of the inferior extremity of the bone, which is articulated with the convex surface on the cor- responding part of the ulna. The inferior ex- tremity of the radius presents, at its outer part, a pyramidal process projecting downwards and slightly outwards ; this is the styloid process, which by its apex gives attachment to the ex- ternal lateral ligament of the wrist-joint. The anterior margin of the inferior extremity is slightly concave from side to side ; it gives at- tachment to the anterior ligament of the wrist- joint, and the tendons of the flexor muscles of the fingers pass over it into the palm of the hand. On the posterior margin of this extremity we observe two grooves : the internal one, wide and very superficial, lodges the tendons of the com- mon extensor of the fingers and the indicator ; the external, deeper and oblique, lodges the extensor tertii internodii pollicis. Externally we notice likewise two superficial grooves, of which the posterior lodges the radial extensors of the wrist, and the anterior is traversed by the extensores primi et secundi internodii pollicis. Structure — The central canal extends up- wards into the neck of the bone; it is cylin- drical at the extremities, and prismatic in the centre. Both extremities are composed of can- cellated structure. Developement of the bones of the fore-arm. — Both bones appear about the same time, and if not synchronously with the humerus, at least a very little later. With both bones the ossifi- cation begins on the shafts, which are very early completed ; the ossific point of the shaft of the radius is said, by Beclard and Cruveil- hier, to begin some days before that of the ulna. In the radius the inferior extremity begins to ossify before the superior, about the end of the second year. The ossification of the superior extremity begins between the seventh and ninth year; it is united to the shaft about the twelfth year, whilst the inferior extremity, whose ossification begins earlier, is not united till the eighteenth or twentieth year. The progress of the ossification of the ulna is very similar. The inferior extremity developed by a single point of ossification begins first, about the sixth year. A little later the olecra- non begins to ossify; the coronoid is formed by an extension of ossification from the shaft. The union of the superior extremity of the ulna with the shaft takes place about the fifteenth or sixteenth year ; that of the inferior about the eighteenth or twentieth. It is important to observe that the articula- tion of the radius with the ulna, in the manner in which it is effected in man, has reference to the motions of the hand. Pronation and supi- nation of the hand are effected by the rotation of the head of the radius within the coronary ligament and on the lesser sigmoid cavity of the ulna. The hand is so connected with the radius that it follows the motions of that bone ; when, therefore, the radius rotates in such a direction that its inferior part crosses the ulna, the posterior edge is directed outwards, and its anterior surface inwards and backwards; the palm of the hand is turned backwards and the dorsum forwards ; the forearm and hand are then said to be in pronation. On the contrary, when the rotation is such that the ulna and ra- dius are placed on the same plane, the dorsum of the hand is directed backwards and the palm forwards ; this is supination. In the lower animals we never find this mode of articulation of the radius with the ulna, unless there be also present the motions of su- pination and pronation of the hand. In such EXTREMITY. 165 animals, evidence of the existence of these motions is afforded by certain points in the conformation of the radius and ulna them- selves, such as the peculiar form of the head of the radius, and the concave articular sur- face on the ulnar side of its lower extremity, as well as the lesser sigmoid cavity of the ulna, and the convexity on the radial side of the head of the same bone. This is found in many of the Carnivora, but chiefly in the Quadru- mana. In the Ruminants and Solipeds the radius and ulna are consolidated together so as to form one bone; they can, however, be distin- guished at the humeral end, where the latter bone is conspicuous by its elongated olecranon, which not only affords insertion to the extensor muscles of the arm, but also increases the secu- rity of the elbow-joint. The radius, which is the principal bone of the fore-arm, is so arti- culated with the humerus as to admit of free flexion and extension, but it is fixed in the state of pronation. In many of the other Mam- malia the radius and ulna are distinct through- out, but do not admit of the rotation of the one on the other; this is the case in Rodentia, many Carnivora, Pachydermata, Edentata, In- sectivora, and Cetacea. In the Sloth, how- ever, among the Edentata, the motions of pro- nation and supination are conspicuous, and the olecranon is imperfectly developed ; on the contrary, in the Edentata proper, as the Arma- dillo, Megatherium, &c. these motions do not exist, and the olecranon is very much deve- loped. In the Cheiroptera the radius is the principal bone of the fore-arm, the ulna being developed only as to its humeral extremity consisting sometimes of little more than its olecranon ; and in some, as the Vespertilio vam- pyrus, the olecranon exists in the form of a pa- tella, connected with the upper extremity of the ulna. In Birds the radius and ulna are distinct throughout, but do not admit of motion between them; they are fixed in a state intermediate be- tween pronation and supination. The Hand.- — The third division of the upper extremity is the hand : for the description of the bones which compose it, we refer to the article Hand. Inferior extremity. — The bones which form the skeleton of the inferior or pelvic extremity are the femur, tibia, fibula, and the bones of the foot, occupying subdivisions of this mem- ber, which correspond to the arm, forearm, and hand in the pectoral extremity. Femur (thigh-bone, os Jemoris v. cruris, os coxa. Fr. os de la cuisse, le femur. Germ, das Schenkelbein.) This is the largest and longest bone of theskeleton; it constitutes the upper part of the inferior extremity, and is articulated with the pelvis above and the tibia inferiorly. The femur exhibits very obviously the characteristic marks of the class of long bones in its elonga- ted and cylindrical shaft, and its swollen extre- mities. The superior extremity of the femur consists of a spherical head, connected to the shaft of the bone by a neck. The head is very regu- larly spheroidal, being nearly two-thirds of a sphere; it is limited towards the neck by a waving line which passes all round, and corre- sponds to the margin of the acetabulum. The whole head of the femur is incrusted in the recent state with articular cartilage, excepting at one point, where there is a depression or pit, varying in depth in different subjects. The precise situation of this depression is just infe- rior and posterior to the point at which the axis of the head of the femur would pass out : into this depression the ligamentum teres is in- serted. From the head of the femur is prolonged outwards and downwards to the upper end of the shaft the neck (cervix v. colium Jemoris ). This portion of bone, cylindrical where it is connected to the head, gradually expands as it proceeds outwards, and is flattened in front and behind. That portion of the neck of the femur which is connected with the shaft may be called its base; here we observe two lines, by which the demarcation between the neck and shaft is indicated ; one of these lines is anterior, being simply a rough line extending from the great trochanter obliquely downwards, inwards, and slightly backwards to the lesser trochanter, and thence called the anterior inter- trochanteric line, into which the capsular liga- ment of the hip-joint is inserted ; the other line may be more correctly designated a prominent ridge ; it is situated at the posterior part of the base of the neck, and extended also between the trochanters, the posterior intertrochanteric line. The anterior surface of the neck of the femur is for the most part plane, but slightly concave just external to the line of junction of the head. The superior surface of the neck is concave, being limited on the outside by the great tro- chanter ; the posterior surface is likewise con- cave, being, as it were, hollowed from within outwards. The inferior surface is slightly con- cave from above downwards, but rounded from before backwards : this surface inclines down- wards and outwards, and at its termination is connected with the trochanter minor behind, and the inner side of the shaft of the bone in front ; in length it exceeds all the rest ; the su- perior surface is the shortest, and the posterior is longer than the anterior. On all the surfaces of the neck we observe numerous foramina for the transmission of vessels into the substance of the bone ; these foramina are largest and most numerous on the superior surface. At the superior angle of the base of the neck of the femur, and at the upper and outer part of the shaft of the bone, we observe a large and thick process, the trochanter major, (from t^o^ocu, roto,) processus exterior Jemoris ; it is a prolongation upwards of the shaft of the bone, but its most elevated point is below the level of the head of the bone, corresponding to the upper part of the line of junction of the head with the neck. " This eminence," says Cruveilhier, " whose size is considerable, and which makes a very manifest prominence under the skin, ought to be studied with care in its relations as to its relative position ; first, witli the crista ilii, beyond which it projects exter- 166 EXTREMITY. nally ; secondly, with the external condyle of the femur; thirdly, with the malleolus exter- nus, because these relations are constantly va- luable guides, as well in the diagnosis as in the reduction, of the luxations of the femur and of the fractures of the neck or shaft of the bone." The external surface of the great trochanter is convex and rough, and the tendon of the gluteus maximus muscle covers it in the recent condition ; this surface is terminated below by a projecting line, into which is inserted the upper extremity of the vastus externus muscle. The internal surface is of much less extent : it is placed at right angles with the superior sur- face of the neck of the bone, and at its posterior part it is excavated so as to form a deep pit or depression, the digital cavity or jfpssd trochante- rica, into which are inserted the tendon of the pyriformis, the gemelli, and the obturatores internus and externus. The anterior edge is thick and irregular ; the glutei medius and minimus are inserted into it, the former into its inferior, the latter into its superior part. Superiorly the trochanter forms a thin edge, more or less pointed, into the interior half of which the gluteus minimus is inserted, and into its posterior or pointed portion the gluteus medius; it may in general be observed, that the size of this pointed part of the superior edge of the great trochanter is proportionate to the developement of the gluteus medius mus- cle. The posterior edge is convex and thick, and gives attachment to the quadratus femoris muscle. At the inferior angle of the base of the cervix femoris, and on the internal and posterior part, we notice a short conical process, trochanter minor, ( processus interior femoris,) attached to the bone by its base, 1 its apex directed downwards, inwards, and backwards, smooth on its whole surface. This process affords insertion to the tendon of the psoas and iliacus muscles. In the maleadult, theaxis of the head and neck of the femur passes downwards, outwards, and slightly backwards, and forms an obtuse angle with the shaft, an angle of about 135 degrees. In the female this angle is somewhat smaller, and approaches more nearly to a right angle, which contributes with the greater lateral dimensions of the pelvis, to increase the distance of the trochanters of opposite sides from each other, and to cause that projection of these processes which forms a peculiarity of the female form. In early age, when the neck of the femur is imperfectly developed, the angle between the neck and shaft is not defined ; in the earliest condition the connexion of the head and shaft very much resembles the permanent condition of the corresponding parts in the humerus ; as the neck becomes developed, the angle is ren- dered apparent, at first, however, little removed from a right angle, but subsequently it in- creases up to the adult period ; after that time we often find that the neck of the bone dimi- nishes in its dimensions, and the angle is con- sequently altered, so as to approximate to a right angle. The following may be given as the mean measurements of the different parts of the neck of the femur. In the centre it measures about one inch, its posterior surface about fifteen lines, its inferior edge about twenty lines, and its superior about eleven lines ; its vertical diameter, in its most contracted part, is about seventeen lines, and its antero-posteiior about ten. The shaft of the femur forms a slight curve from above downwards, convex anteriorly and concave posteriorly, the excavation thus formed behind being filled up by the powerful muscles on the back of the thigh. It likewise presents the appearance as if it had been twisted, like that which we have noticed in the humerus, the inferior extremity being twisted inwards, the superior in the contrary direction. Cru- veilhier remarks, that this curvature of torsion is in relation with the disposition of the femoral artery, which in its spiral course passes from the anterior to the posterior surface of the bone. In the greater part of its extent the shaft of the femur is prismatic ; at the superior extre- mity it is expanded laterally and flattened ; at the inferior it is likewise very considerably ex- panded. The anterior surface of the shaft is smooth and rounded ; at the upper part it is a little rough : this surface is covered completely by the triceps extensor muscle. The posterior surface is divided along the middle into two, which are inclined, the one forwards and in- wards, the other forwards and outwards ; the external surface is covered by the vastus exter- nus, the internal by the vastus internus. In the middle, separating these two surfaces, is a rough ridge, tinea aspera, which occupies two- fifths of the shaft of the bone about its middle, but is bifurcated above and below. Superiorly the bifurcation takes place about the termina- tion of the superior fifth ; two lines proceed, the external, rough and prominent, to the great trochanter ; the internal, rather indistinct, to the lesser trochanter. The external line gives in- sertion to the vastus externus, the adductor magnus, and the gluteus maximus ; the pecti- nffius and the vastus internus are inserted into the internal line. Inferiorly, the bifurcation takes place at a point corresponding to the commencement of the two inferior fifths ; each line proceeds down to the corresponding con- dyle, and a triangular space is thus enclosed, the base of which is formed by the posterior extremities of the condyles, and the apex is at the point of bifurcation of the linea aspera. This space, which presents a smooth surface, slightly concave in both the vertical and trans- verse directions, forms the floor of the popliteal region. The external line, from the inferior bifurcation, is more prominent than the inter- nal, and gives insertion to the vastus externus and to the short head of the biceps. The in- ternal is very faint superiorly where the femoral artery passes over it, and inferiorly the vastus internus and the adductor magnus are inserted into it. The nutritious foramen of the femur is found either upon, or on one side of, the linea aspera. EXTREMITY. 167 The direction of the canal is upwards towards the head of the femur. The inferior extremity of the femur is much more considerable than the superior. We no- tice upon it two articular processes of large size, united in front, but separated by a deep depression posteriorly. These processes are the external and internal condyles ; at the point of union of these two condyles in front, we ob- serve a transversely concave surface, which ex- tends for a little distance upwards upon the anterior surface of the bone ; this is the trochlea of the femur, on which the patella moves. The deep notch which separates the condyles poste- riorly is denominated the intercondyloid notch. Each condyle is ovoidal in its outline and convex. The external condyle is placed di- rectly under the external part of the femur ; it projects more forwards than the internal con- dyle ; its antero-posterior diameter is less than that of the internal condyle, but its trans- verse is greater. On the other hand, the in- ternal condyle projects inwards out of the plane of the internal surface of the bone; its posterior extremity extends much further backwards than that of the external, and if the bone be placed at right angles, with a plane surface, it will be seen that this condyle alone touches that surface, a circumstance which arises from the internal condyle project- ing downwards more than the external. It is also worthy of notice, as resulting from this conformation of the internal condyle, that in order to bring both condyles in contact with a plane surface, the bone must be made to in- cline with the inferior extremity inwards. Above the posterior extremity of each condyle there is a depression for the insertion of the two heads of the gastrocnemius muscle. The external surface of the external condyle is continuous with the outer surface of the shaft; it is rough and convex, and is called by some anatomists the external tuberosity. At its" posterior part there is a prominent tubercle to which the external lateral ligament is attached, and below and a little posterior to this is a de- pression into which the tendon of the popliteus is inserted. The internal surface of this con- dyle forms the outer wall of the depression which separates the condyles behind ; it is concave, and has the anterior crucial ligament inserted into it. The inner wall of this notch is formed by the external surface of the in- ternal condyle, which is likewise concave, and into it are implanted the fibres of the pos- terior crucial ligament. The internal surface of this condyle, or the internal tuberosity, is rough, much more convex than the external tuberosity; the internal lateral ligament and tendon of the adductor magnus are inserted into it. Both the tuberosities are perforated by a number of minute foramina for the trans- mission of vessels to the cancellated texture. Structure. — A vertical section of the femur demonstrates its structure to be the same as that of all the long bones, composed of can- cellated texture at the extremities and com- pact in the shaft, which is bored by a cylin- drical canal. Posteriorly the compact tissue is of great density and hardness, especially where it forms the linea aspera or spine of the bone. When the section of the femur is made so as to divide the neck vertically in its long axis into two equal portions, we observe how ad- mirably the arrangement of the osseous texture in this part is adapted to the function which it has to perform. The head is entirely composed of reticular texture surrounded by a thin cortex ; this cortex gradually increases in thickness on the upper surface of the neck till it reaches the great trochanter. On the inferior surface of the neck, however, the compact tissue, although thin near the head, becomes very much in- creased in thickness as it curves downwards and outwards to the lesser trochanter. We observe, moreover, that although the principal portion of the head and neck are composed of reticular texture, in certain parts this texture is more loose than in others. From the upper part of the head to the thick part of the compact tissue on the inferior surface of the neck, a series of parallel fibres proceed in an oblique course, and closely applied to one another; these fibres receive and transmit the weight to the arch of the neck. Again, the reticular texture is loose and rare, external to these fibres and in all the inferior part of the head of the bone where no stress is laid upon the bone. Developemenl. — According to Beclard, the femur begins to ossify before the humerus; its ossification commences about the thirtieth day by a point for the shaft. A second point of ossification is for the inferior extremity, and this consists in a single osseous nucleus which is formed within the last month of foetal ex- istence, and is situated between the two con- dyles, occupying the centre of the cartilage. According to Cruveilhier this osseous nucleus appears during the last fifteen days of intra- uterine life. " The constant presence," adds this author, " of this osseous point in the inferior extremity of the femur is a fact of great im- portance in legal medicine ; because from the knowledge of this circumstance alone, namely, that this nucleus exists in the epiphysis of the inferior extremity of the femur of a fetus, we can pronounce that fetus to have arrived at its full period." The neck of the femur is formed by an ex- tension from the body. The head has a distinct point of ossification which begins to form at the end of the first year. The trochanters have each a separate point of ossification ; that of the great trochanter is formed about the third or fourth year, that of the lesser from the thir- teenth to the fourteenth year. These several osseous points are united to the shaft about the period of puberty in the following order ; first, the trochanter minor, next the head and trochan- ter major, and lastly the inferior extremity. In the skeleton the femur is articulated so that its inferior extremity approximates the corresponding part of the bone of the op- posite side, while the superior extremities are separated from each other to a considerable extent. One object of this oblique position of the femora has been already referred to, namely, to bring both condyles of each femur in con- 168 EXTREMITY. tact with the articular surfaces of the vertical tibiae. In women, in consequence of the more horizontal position of the neck of the femur and the greater width of the pelvis, the ob- liquity is more manifest, and hence they are naturally more in-kneed than men, as from the greater projection of the internal condyle that surface alone would come in contact with the tibia if the position of the femur were vertical. The separation above is ef- fected by the neck of the bone, and the ad- vantage of this arrangement is to give a more favourable insertion to the muscles of rotation ; they thus acquire a lever power proportionate to the length of the neck, a fact which is abundantly manifest by comparing the relative powers of rotation in the shoulder and hip joints; in the former these motions are more extensive, because, from the peculiar form of the joint, the obstacles to extent of motion are fewer; in the latter they are effected with greater power at a less expense of muscular force. In comparing the femur of man with that of the lower mammalia, we notice the imperfect developement or the non-developement of the cervix in the latter, the head in some being placed nearly vertically over the shaft of the bone, and also the small size of the trochanters, and the magnitude of the trochanter major in some classes. The curved form of the shaft of the femur is much less in the lower mammalia than in man ; in some the femur is perfectly straight, and as a consequence the linea aspera or spine is indistinctly marked. The propor- tionate length of the femur to the other bones of the inferior extremity differs also : in man it exceeds that of the tibia; in the inferior mammalia, although in most cases the strongest bone, the femur is shorter than the tibia, and shorter even than the foot, although longer than each segment of this portion of the limb. The trochlea in the inferior extremity is deeper, and the transverse dimensions of the condyles are less than in man. Patella, (rotula, knee-pan, os sesamoideum maximum, Bertin ; Fr. la rotule ; Germ, die Kniesclieibe ). This bone, although belonging to the class of sesamoid bones, is yet so fully developed in the adult human subject, and is so essential to the integrity of the knee-joint, that it is usual to examine its anatomical characters along with those of the other bones of the in- ferior extremity. Its developement in the tendon of the rectus femoris leads to its being classed among the sesamoid bones. The patella is of a triangular form, the apex being directed downwards and the base up- wards ; the former is connected with the tibia by the continued tendon of the rectus, under the name of ligamentum patellae; the tendon of the rectus and the tendinous expansions of the triceps extensor are inserted into the base, which expansions are likewise implanted into the margins of the bone, so that the whole circumference and anterior surface of the pa- tella are invested with tendinous fibres. The anterior surface of the patella is very slightly convex, and exhibits a fibrous ap- pearance produced by vertical and parallel fibres, with narrow fissures between, into which the fibrous expansion which invests this surface is implanted. The posterior surface is articular and adapted to the trochlea of the femur. A vertical ridge, which inclines a little outwards in its descent, divides this sur- face into two lateral portions ; each of these por- tions is a concave articular facet for adaptation to the anterior part of each condyle of the femur, and consequently there is between these surfaces the same inequality which exists be- tween the condyles. In the recent condition these surfaces are covered by a soft and very elastic cartilage. Structure and developement. — The patella is entirely composed of cancellated texture, the anterior surface being covered by a thin lamella of very fibrous compact tissue already referred to. This bone is developed by a single point of ossification, which commences about the second year. The patella exists pretty generally among Mammalia, also among Birds. It is most de- veloped in the Pachydermata and the Solipeds, and also in the Monotremata ; and least so in the Carnivora and Quadrumana. It is absent in Cheiroptera and Marsupiata.* Leg. — The bones that form the second segment of the inferior extremity are the Tibia and Fibula. Tibia, (shin-bone; Germ, das Schienbein.) This bone is situated between the inferior ex- tremity of the femur and the astragalus. Its length is to that of the femur as five to six. It forms the principal support of the leg, on the inside of which it is placed, and its volume is five times that of the fibula. After the femur, it is the longest bone in the body, being longer than the humerus. The upper or femoral extremity of the tibia is thicker and broader than the remaining parts of the bone, and is properly the head of the bone. Its transverse extent is much greater than its antero-posterior. Its superior surface presents two bony processes lying on the same plane, denominated condyles of the tibia. Each of these has upon its superior surface a superficial concave articular facet, oval with long axis from before backwards; to these surfaces the term condyle has been improperly applied ; but they are more correctly called the glenoid cavities of the tibia, ( cavilates glenoidea, ex- terna et interna). These cavities correspond to the condyles of the femur, having the semi- lunar cartilages interposed ; the outer cavity approaches more to the circular form than the internal one ; it is likewise much less deep, and at its posterior part it is even convex. The internal one, on the other hand, is uniformly concave, and its antero-posterior axis greatly exceeds its transverse. These sur- faces are separated in the centre by a pyra- midal eminence whose apex appears bifurcated, the subdivisions of which are separated by a narrow rough space. This is the spine of the tibia, (acclivitas intercondyloidea ) ; it corres ponds to the intercondyloid' fossa of the femur * Meckel, Anat. Compar. EXTREMITY. 169 where the crucial ligaments are attached. Anterior and posterior to this spine are two rough depressions, the posterior more hollowed than the anterior : into the former the posterior crucial ligament is inserted, and the latter re- ceives the anterior crucial ligament. The circumference of the head is rough and perforated by a vast number of minute vas- cular foramina. Each condyle projects late- rally beyond the plane of the corresponding surface of the shaft, the internal to a greater extent than the external. These lateral pro- jections are distinguished by the name of Tu- berosities. The internal tuberosity gives in- sertion at its lower part to the internal lateral ligament of the knee-joint; posteriorly this tuberosity is grooved, and one of the tendons of the semi-membranosus is inserted into the groove, and separates the internal lateral ligament from the bone in this situation. At the pos- terior part of the external tuberosity there is a small articular facet, nearly circular and plane, with which the fibula is articulated. In front of the head of the tibia there is a rough triangular surface, the apex of which is directed downwards and forms a promi- nence, which is smooth at its superior part, but rough inferiorly. The ligamentum patellae is inserted in the latter situation ; the smooth portion indicates the position of a bursa which intervenes between the ligament and the bone. This prominence is called the anterior tube- rosity, and by some anatomists the spine. From the inferior rough portion of this tube- rosity there passes upwards and outwards a prominent line, most prominent at its ter- mination, where the tibialis anticus muscle has one of its attachments. The shaft of the tibia has the form of a triangular prism in almost its whole extent: at its inferior third this form is less distinct, in consequence of the angles being rounded off. Of the three surfaces the anterior is that which presents the greatest dimensions : it is smooth and slightly convex in its entire extent, in- clined backwards and inwards, subcutaneous, except at its upper part, where an aponeurotic expansion connected with the tendons of the semi-tendinosus, sartorius, and gracilis muscles. The inferior fourth of this surface is much more convex than the upper portion, and looks directly inwards. The external surface is in- clined backwards and outwards, and is con- cave in its three superior fifths, convex in the rest of its extent. The depth of the superior concave portion is proportionate to the de- velopement of the tibialis anticus muscle, to which it gives insertion. The inferior con- vex portion is of less extent than the superior, and as it descends it experiences a change of aspect, so as to look directly forwards. This change is in accordance with the altered di- rection of the tendons of the tibialis anticus and extensor muscles of the toes, which lie in contact with the bone in this situation. The posterior surface is expanded at its extremities and contracted in the centre. At its superior part a triangular surface is marked off from the rest, towards the upper extremity by an oblique line, which proceeds from below up- wards, and from within outwards; into this line are inserted the poplitasus, soloeus, tibialis posticus, and the long flexor muscle of the toes. The space which intervenes between this line and the posterior margin of the head of the bone is covered by the poplitaeus muscle and forms part of the floor of the popliteal space. Immediately below this oblique line, the orifice of the nutritious canal is situated, penetrating the bone obliquely downwards ; this canal is the largest of the medullary canals of the long bones ; and Cruveilhier states that he has traced a nervous filament passing into it in company with its artery. All that portion of the posterior surface which is below the oblique line is smooth and divided by a ver- tical line, which is variously developed in dif- ferent subjects; the tibialis posticus muscle and the long flexor of the toes are attached to this surface. Three distinct edges separate these surfaces. The anterior edge ( crista tibia ) is very promi- nent and sharp in its three superior fourths, but rounded off below : in its upper part it is quite subcutaneous, and may be felt under the skin. The external edge forms a very distinct line of demarcation between the internal and posterior surfaces ; it gives attachment to the interosseous ligament, and at its inferior extremity it bifur- cates and encloses a concave triangular surface, in which the fibula rests. The internal edge is more rounded than either of the others ; more distinct inferiorly than superiorly. At its up- per end it gives insertion to the internal lateral ligament of the knee-joint and the popliteus muscle, and lower down to the solceus and the common flexor of the toes. ^^.j..-—— The inferior or tarsal extneihity of the tibia is of larger dimensions than the shaft, although much smaller than the superior. On its infe- rior surface we notice a quadrilateral articular cavity, of greater dimensions transversely than from before backwards, concave in this latter direction, and slightly convex transversely, in consequence of the existence of a slight ridge in the centre, which passes from before backwards. This surface is for articulation with the supe- rior part of the body of the astragalus to form the ankle-joint. The anterior surface of the inferior extremity of the tibia is convex and rough ; it gives in- sertion to the anterior ligamentous fibres of the ankle-joint, and the tendons of the extensor muscles pass over it. The posterior surface is very slightly convex ; sometimes a very super- ficial groove exists upon it for lodging the ten- don of the flexor pollicis longus ; and internal to that, and lying behind the internal malleolus, a more distinct and constant groove, which passes obliquely downwards and inwards, and lodges the tendons of the tibialis posticus and flexor communis. On the inside of the inferior extremity, we observe that the bone is prolonged downwards and slightly inwards, forming a thick and flat- tened process, quadrilateral in form, called malleolus interims. The internal surface of this process is rough and convex; it is quite 170 EXTREMITY. subcutaneous; its external surface is smooth, and exhibits a triangular articular facet, which is united at a little more than a right angle with the articular surface on the inferior extremity of the tibia; by this facet the internal malleolus moves on the inner surface of the body of the astragalus. The apex of the mal- leolus has the internal lateral ligament of the ankle-joint inserted into it ; the anterior edge gives insertion to ligamentous fibres, and the posterior edge, much thicker than the antgrior, is closely connected with the posterior surface of the inferior extremity of the tibia, and has upon it the oblique groove already referred to. In comparing the position of the malleolus in- ternus with that of the internal tuberosity of the tibia, (which may best be done by laying the bone on its posterior surface on a horizontal plane,) it will be observed that the malleolus is considerably anterior to the tuberosity, a fact which is attributable to the same cause which occasions the change of aspect in the inferior part of each of the three surfaces of the shaft, namely, a torsion of the bone similar to that already noticed in the other long bones of the extremities. This torsion is manifest at the junction of the inferior and middle thirds, the lower part having the appearance of being twisted inwards, and the upper part outwards. The outer side of the tarsal extremity of the tibia is excavated so as to form a triangular surface, rough in its entire extent, to which the fibula is applied, and into which are implanted the strong ligamentous fibres by which that bone is tied to the tibia. Structure. — The cancellated texture is accu- mulate^ in large quantity at the extremities, where, especially at the superior, a line is very frequently apparent on the whole circumference, indicating the place of junction of the epiphysis and shaft. The medullary canal is large, ap- proaching the cylindrical form, and surrounded by a dense compact tissue. Fibula (Fr.perone; Germ. Wadenbein). — This bone is situated on the outer and posterior part of the tibia. It is about the same length as that bone, but as its upper extremity is ap- plied to the under surface of the external tube- rosity, its inferior extremity projects below that of the tibia. There is a slight obliquity in its direction, and in consequence, its inferior extre- mity advances more forwards than its superior. The fibula is a very slender bone in its entire extent, however its extremities are a little enlarged. The superior extremity or head of the fibula (capitulum) is somewhat rounded on its inner side, flattened on its external surface, terminating superiorly in a point into which the external lateral ligament of the knee-joint is inserted, anterior and posterior to which the edge of the bone receives the tendon of the biceps muscle. At the upper and anterior part of its internal surface there is a small sur- face nearly plane, which is articulated with a similar one on the external tuberosity of the tibia. On the shaft of the fibula we may dis- tinguish three surfaces, but in consequence of the great extent to which the fibula appears to have undergone torsion, it is at first difficult to detect the lines of demarcation between these surfaces. The ex ternal surface is very narrow and convex in its upper third, gradually ex- pands as it descends, and becomes hollowed out in its middle third, where it receives the peroncei muscles ; in both these portions the aspect of this surface is outwards and slightly forwards. In the inferior third it is quite flat, and its aspect is outwards and backwards. The internal surface has a longitudinal sharp ridge upon it, which gives insertion to the interosse- ous ligament. This crest divides the internal surface into two portions; the anterior, very small, in some cases not exceeding two or three lines, gives attachment to the extensor muscles of the toes and the peronaeus tertius ; the pos- terior, much more considerable and slightly concave longitudinally for about its two supe- rior thirds, has the tibialis posticus inserted into it. This surface, which above looks nearly directly inwards, looks forwards in its inferior third. The posterior surface is also very nar- row above, and expands as it descends ; upon it the twist in the bone is very obvious. In its superior third this surface looks outwards and backwards ; in its middle third, where it is much more expanded, it looks directly back- wards ; and in its inferior third its aspect is inwards, and here it terminates in forming a rough surface which is adapted to the similar one on the fibular side of the inferior extremity of the tibia. Superiorly the posterior surface of the tibia gives attachment to the soloeus muscle, and lower down to the flexor pollicis proprius. The orifice of the nutritious canal, directed down- wards and forwards, is found here. A knowledge of the edges which separate these surfaces will assist the student in understanding the position of the surfaces themselves. The anterior edge begins just below the head, passes down in front of the bone as far as the middle, then becomes exter- nal and bifurcates, enclosing a triangular sur- face on the outside of the inferior extremity of the bone, which is quite subcutaneous. The external edge is at first external, and about the commencement of the inferior third it begins to wind round so as ultimately to become posterior. The internal edge, which is the most acute, and is more prominent in the centre than at its extremities, passes forwards inferiorly, and terminates in front of the inferior extre- mity of the bone : below it gives attachment to the interosseous ligament. The inferior extremity is long and flat, and terminates in a point; it extends entirely below the inferior articular surface on the tibia, and, as Cruveilhier aptly remarks, it forms exter- nally the pendant to the malleolus internus, which it exceeds in length and thickness ; it is consequently called the malleolus externus. The internal surface of the external malleolus presents in its anterior two-thirds a plane triangular surface for articulation with the astragalus; behind this surface there is an excavation, which is rough, and gives insertion to the posterior external lateral ligament. The external surface is convex and subcutaneous, and the posterior surface is grooved for the EYE. 171 passage of the tendons of the peronan muscles. The apex of the malleolus is directed down- wards, and is the point of attachment of the middle external lateral ligament. Structure. — This bone is very light and elastic, a property rendered necessary by the antagonist muscles which are inserted into its opposite surfaces. Its extremities are composed of cancellated structure, which extends some way to the shaft of the bone. The medullary canal, very narrow and irregular, is found only in its middle third. Developement of the bones of the leg. — The tibia begins to ossify somewhat earlier than the fibula. Both bones begin to ossify in their shafts ; the ossific point of the shaft of the tibia appears about the middle of the second month. According to Meckel, in the embryo of ten weeks, the fibula is not above half the length of the tibia; after the third month the two bones are nearly equal. Both bones have an ossific point for each extremity. The superior extremity of the tibia begins to ossify towards the termination of the first year after birth. The inferior extre- mity is ossified in the course of the second year : the external malleolus is a prolongation of the inferior extremity. The union of the extremities with the shaft commences by the inferior, and is completed from the eighteenth to the twenty-fifth year. The ossification of the fibula follows nearly the same course, excepting that the superior extremity does not begin to ossify till the fifth year. The tibia constitutes the principal pillar of support to the leg. It is placed perpendicu- larly under the femur, and as the latter bone is inclined inwards, it follows that there must be an angle formed between these two bones at the knee-joint, a very obtuse one, with its apex inwards.'* It is then by the strength and direction of the tibia that the leg firmly sup- ports the body in the erect attitude; the fibula seems not to contribute at all to the solidity of the limb, but is chiefly employed to increase the surface of attachment for the muscles of the leg. The developement of the tibia and fibula in the inferior mammalia is pretty similar to that of the radius and ulna. The tibia is always fully developed, and, as in man, is the prin- cipal bone of the leg, its size being pro- portionate to the weight and strength of the animal. Admitting the fibula to be the ana- logue of the latter bone, we find that, as it is rudimentary in the Solipeds and Ruminants, so the fibula is in a similar condition in these animals. In the former animals this bone is applied to the external side of the head of the tibia in the form of an elongated stilet, termi- nating less than half way down in a fine point. On the other hand, in Ruminants it is only the inferior part of the fibula that is developed ; it appears under the form of a small narrow bone, extending a very little way upwards, and form- ing the external malleolus. * A preternatural obliquity of the femur causes a corresponding divergence of the tibia from the perpendicular. When the femur is directed un- usually inwards, the tibia is directed downwards and outwards. In Pachydermata the fibula is fully deve- loped and quite distinct from the tibia, and very small in proportion. In Edentata the two bones are fully developed, and in the Sloths the inferior extremity of the fibula con- tributes to form the articular surface for the astragalus. In Rodentia the two bones are united together in the inferior half, as also with the Insectivora, particularly in the Mole. In many Carnivora these bones are fully developed and detached : this is particularly manifest in the Pbocida; and the Felidae. In the Dogs, however, the fibula is attached to the posterior part of the tibia. For the description of the bones composing the foot, we refer to the article under that head ; and for further details on the osseous system of the extremities, we refer to the articles Osseous System (Comp. Anat.) and Skeleton. Abnormal condition of the bones of the extre- mities.— A congenital malformation of one or more of the extremities is classed by Isidore Geoffroy St. Hilaire among what he denomi- nates " Monstres Ectromeliens," of which he has three subdivisions : 1st, where the hands or feet appear to exist alone, and seem to be connected with the trunk without the inter- vention of all or some of the intermediate segments ; these he denominates Phocomeles, {(puxri, Phoca, and p.EXo;, membrum,) from their resemblance to the permanent condition of the aquatic mammalia : 2d, cases in which there are one or more incomplete limbs terminating in the form of stumps : to these he gives the name Hemimeles: and, lastly, where the limb or limbs are wholly absent or scarcely at all developed. An interesting case of Phoco- melia is recorded by Dumeril ; all the limbs were in this condition, owing to the absence of the humerus, and forearm bones in the upper extremity, and the presence of a very imperfect femur, developed only as to the head and tro- chanters, and a very imperfect tibia in the lower extremity. The clavicle and scapula were pre- sent, but presented some irregularities of form.* The congenitaj absence of these last bones is rare excepting where the other bones of the limb are also absent. It would be inconsistent with the objects of this article to prosecute this subject further; we therefore refer for further details to the article Monstrosity. For Bibliography, see that of Anatomy (Introduction). (R. B. Todd.) EYE, (in human anatomy), ofpOafyto;, orga- nonvisus; oculus. Yr.CEil; Germ, das Auge ; Ital. Occ/ii'o. — The human eye is a hollow sphere, about one inch in diameter, with a circular aperture in the anterior part about one-fifth of this sphere in breadth, filled by a transparent convex portion called the cornea, through which the light is transmitted. Within this hollow * Hull, de la Sor. Philomath, t. iii.( quoted in Geoff. St. Hilaire 's Anom. de 1'OrganizaUon, t. ii. p. 211. 172 EYE. sphere, and at a short distance behind the trans- parent convex portion or cornea, is fixed a double convex lens, called the crystalline lens or crystalline humour; and between this cor- nea and crystalline lens is interposed a parti- tion or screen called the iris, with a circular aperture in its centre called the pupil. The inner surface of this hollow sphere, as well as the back, of the iris or screen, are covered or stained with a black material. The space be- tween the cornea and crystalline lens, in which the iris is placed, is filled with a transparent fluid, called the aqueous humour, and the space between the crystalline lens and the bot- tom of the sphere is filled with a similar fluid, called the vitreous humour. The annexed figure represents a section of this simple piece of opti- cal mechanism, much larger than natural to render the parts more distinct. Fig. 100. An acquaintance with the laws which regu- late the transmission of the rays of light through transparent bodies, and with the manner in which the lenticular form changes the direction of these rays,:teaches ;" ttyat a correct image of ex- ternal objects is form^d-in -the bottom of the eye in consequence of the^above adjustment of its parts. First, the rays of 'light acquire a con- vergence in their passage through the cornea and aqueous humour, then the central portion of the pencil of rays is transmitted through the pupil, and, finally, the rays in their passage through the crystalline lens acquire such addi- tional convergence, that they are brought to a focus on the bottom as represented in the an- nexed diagram. Such are the essential component parts of the eye, considered as a piece of optical me- chanism, but viewed as a piece of anatomical mechanism, its construction is much more com- plicated, and the materials of which it is com- posed are necessarily totally different from those of any human contrivance of a similar nature. It lives in common with the body of which it forms a part, it grows and is repaired ; conse- quently, the animal organisation destined for such functions must constitute an essential part of its construction. The organ derives its permanent spherical form, its external strength, and the support of the delicate parts within it, from a strong opaque membrane called the sclerotic coat; while the convex portion, called cornea, in front, equally strong, being transparent, allows the rays of light to pass without interruption. The interior of the portion of the sphere formed by the sclerotic coat is lined throughout by a soft membrane called the choroid, necessarily con- stituting another hollow sphere, accurately adapted and adhering to the inside of the for- mer. This also has its circular aperture ante- riorly, into which is fitted the screen called iris, as the cornea is fitted into the aperture in the sclerotic. While the external surface of this choroid coat is comparatively rough and coarse in its organization, as it adheres to the equally coarse surface of the sclerotic, the interior is exquisitely smooth and soft, being destined to embrace the retina, another spherically dis- posed membrane of extreme delicacy. The screen called iris, which is fitted into the cir- cular aperture anteriorly, is as different from the choroid coat in its organization as the cor- nea is from the sclerotic: it is perfectly plane, and therefore forms with the concave surface of the cornea a cavity of the shape of a plano- convex lens, called the anterior chamber. In or on the choroid coat the principal vessels and nerves, destined to supply the interior of the organ, are distributed, and in its texture and upon its inner surface is deposited the black material, which in this part of the chamber, as well as on the back of the iris, is so essential a provision. At the anterior margin the choroid is more firmly united to the corresponding mar- gin of the sclerotic by a circular band of pecu- liar structure called the ciliary ligament, and on its inner surface, in the same place, it is fur- Fig. 101. EYE. 173 nished with a circle of prominent folds called ciliary processes, by means of which it is united to the corresponding surface of the hyaloid membrane of the vitreous humour. The an- nexed figure represents a section of this hollow sphere lodged within the sclerotic sphere. The external circle, a a, between the two black lines represents a section of the strong opaque membrane called the sclerotic, which consti- tutes the case or resisting sides of the organ ; b is the transparent lenticular window called cornea, which fills the aperture left in the ante- rior part of the sclerotic for its reception ; d d is the place of union between the sclerotic and cornea, to which the ciliary ligament on the outside of the anterior margin of the choroid sphere corresponds ; e e the circle bounded by the line marking the inner surface of the sclerotic externally, and by the shaded part in- ternally, represents a section of the hollow sphere called choroid. At the point d d, cor- responding to the place of union between the sclerotic and cornea, this choroid projects exter- nally, encroaching upon the sclerotic in a pecu- liar manner, to be presently described as the ciliary ligament; while at the ■same'1 point it projects internally in the shape of- -a" series of folds, to be described as the ciliary processes. The white productions extending from the same points in a vertical direction into the chamber of the aqueous humour, between the eorhe'a ahd crystalline lens, represent a section of - the screen called the iris, f is a section of the crystalline lens. " ?! Fig. 102. a Through a small aperture in the sclerotic apd choroid membranes in the bottom of the eye, the optic nerve is transmitted, and imme- diately expands into a texture of the most ex- quisite delicacy, called the retina. This con- stitutes a third spherically disposed membrane, not however of the same extent as the sclerotic or choroid, being discontinued at a distance of about an eighth of an inch from the anterior margins of these membranes. This is the ner- vous expansion endowed with the peculiar description of sensibility which renders the ani- mal conscious of the presence of light. The globe of the eye, as above described, is ob- viously divided by the iris into two chambers of very unequal dimensions; that in front bound- ed by the cornea being very small, and that behind bounded by the retina being very large. This large posterior chamber is distended by a spherical transparent mass, called the vitreous humour, which does not, however, fill this pos- terior chamber completely, but is discontinued or compressed at a short distance behind the iris, leaving a narrow space between it and that membrane, called the posterior chamber of the aqueous humour. This spherical mass is of ex- tremely soft consistence, and is composed of a delicate transparent cellular membrane called the hyaloid membrane, the cells of which are distended with a transparent fluid. In the small space between the anterior part of the vitreous humour and the back of the iris, called the posterior chamber of the aqueous humour, and lodged in a depression formed for its re- ception in the vitreous humour, is placed the double convex lens called the crystalline lens. The relation of these parts to each other may be seen in the last figure, and the one below represents the optic nerve expanded in the form of a spherical membrane over the sphere of vitreous humour, with the crystalline lens lodged Sn a depression on the anterior part of that sphere, and surrounded by a circle of radiating lines, which are delicate folds corres- ponding to the folds of the choroid, called the ciliary processes. Fig. 103. The piece of animal optical mechanism thus constructed is lodged in an open cavity of the skull called the orbit, and js furnished with six small muscles for its motions inserted into the outside of the sclerotic coat. The transparent cornea through which the light is transmitted is necessarily exposed, and not being in its nature suited to such exposure, is covered with a membrane called conjunctiva, which also extends over the sclerotic, where that membrane con- stitutes the anterior part of the globe, and then being reflected, lines the eyelids, and finally be- comes continuous with the skin of the face. The human eye is, as has been stated above, probably a sphere of about one inch in diameter. Petit, however, who appears to have first made the attempt to determine the proportions of the organ accurately, describes the axis to be to the diameter as 135 to 136, and the younger S6m- merring, apparently from his own observations, as 10 to 9.5. This belief in a slight differ- ence in dimension may, however, have b;ei 174 EYE. adopted from not making allowance for the projection of the cornea, which is a portion of a smaller sphere than the globe itself, and con- sequently projects beyond its circumference. From the flaccid state of the eye even shortly after death, it must be very difficult to measure it accurately. The question is, however, for- tunately of little practical importance. The eyeball of the male is generally a little larger than that of the female ; and if a close inquiry be made into the matte . ., much difference in this respect might probably be detected in different individuals. I have seen the eyeball in an adult of full size not larger than that of a child of five years old ; and there is much apparent difference in consequence of the difference in the depth of the orbit, and in the gape of the eyelids. Although the human eyeball is nearly a perfect sphere, that precise form is obviously not an essential requisite in the construction of a perfect organ of vision. In all the vertebral animals the bottom of the eye, where the retina is expanded, is probably a portion of a correct sphere, but in many the anterior part is com- pressed, or in other words the sphere is trun- cated, to adapt it to the form and dimensions of the head, or to bring the cornea and lens nearer to the retina. In the mysticete whale the axis is to the diameter as 20 to 29 ; in the swan as 7 to 10 ; in the turtle as about 8 to 10 ; and in the cod as 14 to 17. This deviation from the spherical form demands a corresponding provi- sion in the construction of the sclerotic, to be noticed when describing that membrane. For a fuller account of the comparative proportional measurements of the eye, the student is referred to the works of Cuvier and D. W. Sommer- ring, as quoted at the end of this article ; the limits of which do not admit of a greater detail of facts derived from comparative anatomy than the illustration of the description of the human organ absolutely demands. Having attempted to give a general notion of the mechanism of the eye in the preceding paragraphs, it remains to consider each com- ponent part separately, and to determine its organization, properties, and application, as well as the changes to which it is liable from age, disease, or other circumstances. Of the sclerotic membrane. — This, as has been stated, constitutes, with the transpa- rent cornea, the external case upon which the integrity of the more delicate inter- nal parts of the organ depends, otherwise in- capable of preserving their precise relations to each other : without such support the compo- nent structures must fall to pieces, or be crushed by external pressure. The name is derived from the Greek cntM^ou, and it has also been called cornea and cornea opaca in contradistinc- tion to the true or transparent cornea, a structure to which it bears no resemblance whatsoever ; it is the same animal material which exists in all parts of the body where strength with flexi- bility is required, the material which in modern times has been denominated fibrous mem- brane. When carefully freed from all ex- traneous matter by clipping with a pair of scissors under water, it presents the brilliant silvery-white appearance so characteristic of the fibrous membranes. The white streaks which give the fibrous appearance appeal' ar- ranged concentrically as the lines on imper- fectly polished metallic surfaces. It is inelastic as other fibrous membranes, and so strong that it does not tear or yield unless exposed to the greatest violence. Although penetrated by the vessels going into and returning from the in- ternal parts of the eye, it does not appear to have much more red blood circulating through its texture than other tendinous expansions distinguished for their whiteness. The vas- cularity of the anterior part, however, where it is exposed in the living body, constituting the tunica albuginea, or while of the eye, is different from that of the rest of the mem- brane. The four straight muscles are pene- trated by small branches of the ophthalmic artery, the delicate ramifications of which con- verge to the circumference of the cornea, for the nutrition of which membrane they appear to be destined. In the natural state they can scarcely be detected, but when enlarged by in- flammation, present a remarkable appearance, considered by practical writers one of the most characteristic symptoms of inflammation of the eyeball, or, as it is called, iritis. They then appear as numerous distinct vessels, and as they approach the margin of the cornea, become so minute and subdivided, that they can no longer be distinguished as separate vessels, but merely present a uniform red tint, described as a pink zone. The colour of this inflammatory vascula- rity is also characteristic. Whether from the vessels being more arterial than venous, or from their distribution in so white a structure, they present a brilliant pink appearance very different from the deep red of conjunctival in- flammation, which often enables the practi- tioner to pronounce an opinion as to the nature of the disease before he makes a close examin- ation. The inner surface of the sclerotic where it is in contact with the choroid, does not present the same brilliant silver-white appearance that it does externally, being stained with the black colouring matter ; it is also obscured by a thin layer of cellular membrane, by means of which it is united to the external surface of the cho- roid.* This layer of cellular membrane was described by Le Cat, and more particularly by Zinn, as a distinct membrane, and considered to be a continuation of the pia mater ; it is, how- ever, obviously nothing more than the connect- ing material applied here as in other parts of the body where union is requisite. The thickness of the sclerotic is greater m the bottom of the eye than at its anterior part, where it is so thin that it allows the black colour of the choroid to appear through it, giving to this part of the eye a blue tint, particularly remark- able in young persons of delicate frame. The at- tachments of the four straight muscles, how- ever, appear to increase the thickness in this * [Arnold and others describe and figure a serous membrane in this situation ( Spiunwebenhaut , arach- noidal nculi). See the figure of a vertical section of the eye in Arnold uber das Auge, tab. iii. fig. 2, and copied into Mr. Mackenzie's work on the Eye. — Ed.] EYE. 175 situation ; but that there is no general thick- ening in this part from this cause is proved by the thinness of the membrane in the inter- vals between and beneath these tendons. The consequence of this greater thinness of the membrane anteriorly is, that when the eyeball is ruptured by a blow, the laceration takes place at a short distance from the cornea. In animals in whom the eyeball deviates much from a true sphere, as in the horse, ox, sheep, and above all, in the whale, the sclerotic is much thicker posteriorly than anteriorly, being in the latter animal from three quarters to an inch in thickness, while it is not more than a line at its junction with the cornea. The rea- son for the existence of this provision is, that the form of the perfect sphere is preserved by the uniform resistance of the contents, but when these contents are spherical in one part, and flattened in another, the external case must pos- sess strength sufficient to preserve this irregu- larity of form. It is remarkable that this strength is conferred in the class mammalia by giving to the sclerotic increase of thickness, the fibrous structure remaining nearly the same in its nature, while in birds, reptiles, and fishes, the requisite strength is derived from the pre- sence of a cartilaginous cup or portion of sphere, disposed within a very thin fibrous sclerotic. This cartilaginous sclerotic, as it is often called in the books, exists, as far as 1 have been able to ascertain, in these three classes, and is in some individuals very remarkable. In birds it is thin and flexible, giving a degree of elasticity, which distinguishes the eyeball in this class. In fishes, as has been observed by Cuvier and others, the cartilage is always present, and is particularly thick in the sturgeon ; it is even osseous in some, as the sea-bream, from the eye of which animal I have often obtained it in the form of a hard crust by putrefactive maceration. Among the reptiles the turtle presents a good example of this structure. Where the deviation from the spherical form is very great, as in birds, additional provision is made to sustain the form of the organ. This consists of a series of small osseous plates ar- ranged in a circle round the margin of the cor- nea, lapping over each other at the edges, and intimately connected with the fibrous and car- tilaginous layers of the sclerotic. A similar provision exists in* the turtle, and also in the chameleon, and many other lizards, but not perhaps so neatly and perfectly arranged as in birds. It is found in the great fossil reptiles Ichthyosaurus and Plesiosaurus. The sclerotic, like other fibrous membranes, being inelastic and unyielding, does not be- come stretched when fluids accumulate in the eyeball in consequence of inflammation, or in other words, the eyeball does not become en- larged from effusion of serum or secretion of purulent matter into its chambers. To this probably may be attributed the intolerable torture and sense of tension experienced when the eyeball suppurates, as well as the severe pain extending to the temple in some forms of inflammation. The pain in such cases must not, however, be wholly attributed to this dis- tension of an unyielding membrane. The fibrous membranes in general, when affected by rheumatic or arthritic inflammation, become acutely sensible, and the cause of much suffer- ing ; and the sclerotic, when similarly affected, acquires the same description of painful sen- sibility, apparently independent of distension from effusion. In certain forms of inflam- mation and other morbid changes of the eyeball, the sclerotic appears to yield to distension, as in scrofulous inflammation and hydrophthalmia ; but this is not a mechanical stretching, but an alteration in structure at- tended witli a thinning of the membrane, and consequent alteration in the shape of the globe. It appears that the cornea and sclerotic are peculiarly, if not in many instances almost ex- clusively, the seat of the disease in chronic scrofulous inflammation of the eyeball. This inference may, I think, be justly drawn from the fact, that in such cases the sclerotic becomes so much thinned that the dark choroid projects in the form of a tumour, and the eye loses its spherical form ; yet the pupil remains regular, the lens transparent, and the retina sensible to light. When the cornea is destroyed by slough or ulceration in severe ophthalmia, allowing the lens and more or less of the vitreous hu- mour to escape, the sclerotic does not accom- modate itself to the diminished contents by a uniform contraction, but merely falls in ; and when the eye has been completely emptied, it is found many years after the injury folded up into a small irregular mass in the bottom of the orbit. When the organization of the eye is completely destroyed by idiopathic, rheumatic, or syphilitic inflammation, the sclerotic becomes flaccid, and the whole eyeball soft, allovfing the contraction of the four straight muscles to produce corresponding depressions, and thus convert the sphere into a form somewhat cu- bical. Of the cornea. — This is the transparent body which fills the circular aperture in the anterior part of the spherical sclerotic; it is called cornea from its supposed resemblance to transparent horn, and cornea transparent in contradistinction to the sclerotic, which, as has been stated, is called cornea opaca. It is generally described as a transparent structure, serving to the eye the same purpose as the crystal to the watch ; but this is not a correct comparison : the crystal merely transmits the light without changing the direction of the rays ; the cornea, whether it be considered in itself a lens, or as the sphe- rical surface of the aqueous humour, refracts the rays and causes them to converge to a focus. Haller, although he does not directly say that it is a lens, yet states that if held over ■a book it magnifies the letters, which of course results from its lenticular form ; and Cuvier and Biot distinctly call it a meniscus. On the other hand, the Sommerrings, both father and son, describe it as a mere segment of a sphere, the curve of the convexity corresponding to that of the concavity, as in the watch crystal. I consider it to be a lens and a meniscus. If it be removed from the eye a short time after death with a portion of the sclerotic, and dipped in water to smooth its surfaces, it magnifies ob- jects when held between them and the eye, as 176 EYE. stated by Haller ; and sections of the cornea of the eye of the horse, ox, sheep, or other large animals, shew that the part is much thicker in the centre than at the circumference. It is also to be observed that it has the same provi- sion for the preservation of its lenticular form in a correct state as the crystalline lens, as will presently be explained. The statements made by authors respecting the measurements of the curvatures of the surface of the cornea can be considered only as an approximation to the truth. It is obvious that there must be much difficulty in accurately ascertaining the matter during life, and after death the form is so speedily altered by evaporation that the curve cannot remain the same as during life, hence the measurements differ. Haller says it is a portion of a sphere seven lines and a half in diameter; Wintringham that the chord is equal to 1.05 of an inch, the versed sine of this chord 0.29, and consequently the radius is equal to 0.620215 of an inch. Mr. Lloyd, in his Optics, states, on the authority of Chossat, that the surface of the cornea is not spherical but spheroidical. He says, " the bounding surfaces of the refracting media, however, are not spherical but spheroidical. This remark- able fact was long since suspected by M. Petit, but of late has been placed on the clearest evidence by the accurate measurements of Chossat. This author has found that the cornea of the eye of the ox is an ellipsoid of revolution round the greater axis, this axis being inclined inwards about 10°. The ratio of the major axis to the distance between the foci in the generating ellipse he found to be 1.3; and this agreeing very nearly with 1.337, the index of refraction of the aqueous humour, it follows .that parallel rays will be refracted to a focus by the surface of this humour with ma- thematical accuracy." Whether we consider the cornea as a distinct lens, or as constituting the spherical surface of the aqueous humour, there can be no doubt of its importance as an agent in causing the convergence of the rays of light to a focus on the retina in conjunction with the crystalline lens. If other proof were wanted, it is afforded by the comparatively perfect optical mechanism of the eye after the crystalline lens has been removed by the opera- tion for cataract. The vision in such cases, especially in young persons, is often so good that individuals are satisfied with it for the common purposes of life, and do not resort to the use of the usual convex glasses. The cir- cumference of the cornea is not perfectly cir- cular externally, although it is internally; the sclerotic laps a little over it both superiorly and inferiorly, so that it appears a little wider than it is deep, the vertical being to the horizontal diameter as fifteen to sixteen. Although the cornea is in general description considered a simple and uniform membrane, it is undoubtedly composed of three forms of animal structure, as different from each other as any other three in the animal. These are the conjunctiva, which constitutes the exposed sur- face ; the proper cornea, upon which the strength of the part depends ; and the elastic cornea, which lines the inner concave surface. The conjunctiva is evidently a continuation of the skin, which, reflected in the form of a vas- cular membrane, lines the eyelids, from which it is continued as a delicate transparent mem- brane over the anterior part of the globe, ad- hering loosely to the sclerotic, and closely to the cornea. The existence of conjunctiva on the surface of the cornea proper admits of easy demonstration, and its identity of character with the rest of the conjunctiva and skin of satisfactory proof. If the surface, shortly after death, be scraped with the point of a needle, the soft texture of the conjunctiva is easily torn and detached, and the tough, firm, polished surface of the cornea proper exposed ; and if the eye be allowed to remain for forty-eight hours in water, the whole layer may by a little care be turned off in the form of a distinct membrane. During life, patches of the con- junctiva are frequently scraped off by accident, or by the point of the needle of the surgeon as he attempts to remove foreign bodies implanted in the cornea proper; it is also occasionally ac- cidentally removed by lime or other escharotics. When the vessels of the conjunctiva over the sclerotic become enlarged, and filled with red blood in consequence of preceding inflamma- tion, that over the cornea at length becomes equally red, and has its transparency greatly impaired by the vascular ramifications. • In pustular ophthalmia, the pustules form on the conjunctiva over the cornea as well as on that over the sclerotic ; and in small-pox, vision is frequently destroyed by this part of the tegu- mentary membrane participating in the general disease. In cases where the surface is con- stantly exposed to the atmosphere in conse- quence of prominent staphyloma or destruc- tion or eversion of the eyelids, the conjunctiva of the cornea occasionally becomes covered with cuticle in common with the rest of the membrane. In animals over whose eyes the skin is continued without forming eyelids, the continuity of it over the cornea is obvious. In the mole-rat ( Aspalax xemni.), where the skin is uninterruptedly continued over the eye, the hairs grow from the part over the cornea as well as from the rest. When snakes cast their covering, the cuticle is detached from the cornea as well as from the rest of the body; and when the skin is drawn off the body of an eel, it is detached with equal ease from the cornea as from the rest of the eye. The cornea proper, upon which the strength of this part of the eye depends, is the structure to which the appellation cornea is generally exclusively applied ; it is, as might very rea- sonably be expected from the office which it performs, a material of peculiar nature and organization, not identical with any other of the' simple membranes. During life, and before it becomes altered by the changes which take place after death, it is perfectly trans- parent, colourless, and apparently homoge- neous. This perfect transparency, however, depends upon the peculiar relation of the component parts of its texture, for if the eye- ball of an animal recently dead be firmly squeezed, the cornea is rendered completely opaque, by altering that relation of parts, and EYE. 177 as speedily recovers its transparency upon the removal of the pressure. The chemical com- position of the cornea is similar to that of the fibrous membranes in general and the sclerotic in particular : like the latter structure, it is con- verted into gelatine by boiling ; but Berzelius states that it contains also a small quantity of fibrine or coagulated albumen, as proved by the formation of a precipitate upon adding the cyanuret of ferro-prussiate of potass to acetic acid, in which the membrane has been digested. The cornea possesses great strength, being seldom or never ruptured by blows on the eye- ball, which frequently tear the sclerotic exten- sively. It does not yield to distension from increased secretion, effusion, or suppuration within the eyeball in consequence of inflam- mation, but it becomes extended and altered by growth both in shape and dimensions, as may be observed in prominent staphyloma, lvydrophthalmia, and that peculiar alteration called staphyloma pellucidum, in which the spherical form of the membrane degenerates into a cone, but retains its transparency. The cornea is destitute of red vessels, yet it affords a signal example of colourless and transparent texture possessing vital powers inferior to no other. No structure in the body appears more capable of uniting by the first intention. The wound inflicted in extracting a cataract is often healed in forty-eight hours, yet the lips are bathed internally with the aqueous humour, and externally with the tears. Ulcers fill up and cicatrize upon its surface ; and al- though the vessels, under such circumstances, frequently become so much enlarged as to admit red blood, yet there can be no doubt that ulcers do heal without a single red vessel making its appearance. Abscesses form in the cornea, and contain purulent matter of the same appearance as elsewhere ; they are gene- rally said to be between the layers of the cornea, but they are evidently distinct cavities circumscribed by the inflammatory process as i. ^her cases; occasionally, however, the whole texture of the cornea becomes infil- trated with purulent matter, as the cellular membrane in erysipelas. The rapidity with which this membrane is destroyed by the ul- cerative process is another proof of its superior vitality. In a few days a mere speck of ulce- ration, the consequence of a pustule, extends through the entire thickness, and permits the iris to protrude; and in gonorrhoeal and infantile purulent ophthalmia, the process is much more rapid and extensive. It is true that in the latter case the destruction is attributed to gan- grene or sloughing, and to a certain extent correctly; but an accurate observer must admit that the two processes co-operate in the pro- duction of the lamentable consequences which result from these diseases. Ulcers of the cornea fill up by granulation and cicatrize as in other parts of the body, but the repaired part does not possess the original organization, and is consequently destitute of that transparency and regularity of surface so essential for its func- tions ; hence the various forms and degrees of VOL. II. opacity enumerated under the technical titles of albugo, leucoma, margarita, nebula, &c. which are probably never remedied, however minute they may be, notwithstanding the ge- neral reliance placed in the various stimulating applications made for this purpose. Slight opacities, or nebula as they are called, if con- fined to the conjunctival covering of the cornea, gradually disappear after the inflammation sub- sides, as does also diffused opacity of the cornea itself, the consequence of scrofulous inflammation ; but I believe opacities from ulceration and cicatrix are seldom if ever re- moved. The effect of acute inflammation is to render this, and perhaps all transparent and colourless membranes, white and opaque with- out producing redness ; this may be seen in wounds, where the edges speedily become gray ; and in the white circle which frequently occupies the margin of the cornea in the in- flammations of the eyeball commonly called iritis. The cornea in a state of health is destitute of sensibility. Of this I have frequently sa- tisfied myself by actual experiment in cases of injury of the eye, where the texture of the part is exposed. When foreign bodies, such as specks of steel or other metals, are lodged in its structure, the surgeon experiences much dif- ficulty in his attempts to remove them, from the extremely painful sensibility of the con- junctiva as he touches it with his needle ; but the moment he strikes the point of the instru- ment beneath the foreign body into the cornea itself, the eye becomes steady, and he may touch, scrape, or cut any part of the membrane uncovered by conjunctiva without complaint. It has already been stated that the cornea, as it constitutes the transparent medium for the passage of the rays of light, is composed of three distinct forms of structure altogether dif- ferent from each other, the conjunctiva, the cornea proper, and the elastic cornea. The latter membrane is now to be described. In many of our books this membrane is vaguely alluded to as the membrane of the aqueous humour ; but with this it must not for a mo- ment be confounded. It is a distinct provision for a specific purpose, totally different from that for which the other is provided. It was known to and described by Duddell, Decemet, Demours, and latterly by Mr. Sawrey ; but all these authors having unfortunately published their accounts in separate and probably small treatises, not preserved in any journal, I have not been able to consult them. It is, however, distinctly recognized by Clemens, D. W. Sommerring, Blainville, and Hegar ; and in a paper on the anatomy of the eye in the Me- dico-Chirurgical Transactions, I endeavoured to direct attention to it without effect. The struc- ture here alluded to is a firm, elastic, exqui- sitely transparent membrane, exactly applied to the inner surface of the cornea proper, and se- parating it from the aqueous humour. When the eye has been macerated for a week or ten days in water, by which the cornea proper is rendered completely opaque, this membrane re- N 178 EYE. tains its transparency perfectly ; it also retains its transparency after long-continued immersion in alcohol, or even in boiling water. When detached, it curls up and does not fall flaccid or float loosely in water, as other delicate mem- branes. It also presents a peculiar sparkling- appearance in water, depending upon its greater refractive power; in fact it presents all the characters of cartilage, and is evidently of pre- cisely the same nature as the capsule of the crystalline lens. When the cornea proper is penetrated by ulceration, a small vesicular trans- parent prominence has been repeatedly ob- served in ihe bottom of the ulcer, confining for a time the aqueous humour, but ultimately giving way, and allowing that fluid to escape, and the iris to prolapse; there can be little doubt that it is this membrane which presents this appearance. In syphilitic iritis, this mem- brane becomes partially opaque, appearing d usted or speckled over with small dots altogether different in appearance from any form of opacity observed on the conjunctiva or cornea proper. When it has been touched by the point of the needle in breaking up a cataract, an opacity is produced closely resembling cap- sular cataract. There is no difficulty in pre- paring and demonstrating this membrane in the eye of the sheep, ox, and especially the horse, and it may with a little care be exhibited in the human and other smaller eyes. The eye of a horse having been macerated in water for six or eight days, or until the cornea proper be- comes white, should be grasped in the left hand so as to render the anterior part plump, and then inserting the point of a sharp knife into the structure of the cornea at its junction with the scleiotic, layer after layer should be gra- dually divided by repeated touches round the circumference, until the whole thickness is cut through and the transparent elastic cornea ap- pears, after which the cornea proper may be turned off by pulling it gently with the forceps. The use of the elastic cornea does not appear to me doubtful. The crystalline lens is lodged in a capsule of precisely the same nature, evi- dently destined to preserve correctly the curva- ture of each surface of that body, a condition obviously necessary to secure the perfection of the optical mechanism of the organ. The elastic cornea in the same way, by its firmness, resistance, and elasticity, preserves the requi- site permanent correct curvature of the flaccid cornea proper. The cornea proper is closely and intimately connected to the sclerotic at its circumference. There does not appear to be any mechanical adaptation resembling the fitting of a watch-glass into the bezel, as stated in books; but a ming- ling of texture, as in many other instances in the body. The two structures cannot be separated without anatomical artifice and much vio- lence. If the eye be macerated in water for a month, and then plunged into boiling water, the cornea may be torn from the sclerotic ; but these destructive processes prove little with re- gard to animal organization. The conjunctival covering of the cornea is, as has been already stated,eontinuouswith the rest of the conjunctiva, and the elastic cornea is continued for a short distance beneath the sclerotic, as if slipped in between it and the ciliary ligament. The cornea, thus composed of three different structures, varies in appearance at different periods of life. In the fetus at birth it is slightly cloudy, and even of a pinkish tint, as if it contained some red particles in its blood ; this is, however, more apparent on examination after death than during life ; it is also thicker in its centre. In old age it is harder, tougher, and less transparent than in youth, and fre- quently becomes completely opaque at its cir- cumference, presenting the appearance denomi- nated in the books arcus senilis. How far the alteration in the power of adaptation to distance, which occurs in advanced life, is to be attri- buted to change in curvature of the cornea, is not settled. If the foregoing account be correct, the ap- parently simple transparent body which fills the aperture in the anterior part of the sclerotic, is composed of three distinct varieties of organic structure, liable to changes from disease equally distinct and varied. When the aqueous hu- mour becomes the subject of description, I will endeavour to shew that there is good rea- son for believing that a fourth may be added to these three, the membrane which lines the chamber in which this fluid is lodged, and by which it is secreted. Let it not be supposed that this division of an apparently simple piece of organization into so many distinct parts, is merely an exhibition of minute anatomical re- finement. The distinction is essentially neces- sary to enable the surgeon to account for the appearances produced by disease in this part, and to guide him in the diagnosis and treat- ment. Of the choroid coat. — This membrane has been so called from its supposed resem- blance to the chorion of the gravid uterus; it has also sometimes been called uvea from its resemblance to a grape, a term, howevei, which is now more frequently applied to the iris. It has already been stated that the spherical external case of the eye called the sclerotic embraces another spherically disposed membrane, called the choroid coat, accurately fitted and adhering to it throughout. This spherically disposed membrane has also its cir- cular aperture anteriorly, into which is fitted the screen or diaphragm called the iris. This choroid membrane cannot be considered essen- tial to the perfection of the organ considered merely as a piece of optical mechanism, as a spherical camera obscura, but is obviously an important part of its anatomical organization, and an essential provision for the perfection of its vital functions. It appears to be destined to secure the requisite mechanical connexion be- tween the coarser and more rigid sclerotic case and the parts within, as well as to secure these delicate parts in their situation, and preserve their form, at the same time affording a me- dium for the distribution and support of the vessels and nerves. , EYE. 179 This membrane is of a deep brown or black colour, being stained with the colouring matter called the black pigment; but when this is removed, it exhibits a high degree of arterial and venous vascularity. Its external surface is comparatively rough, coarse, and flocculent, and obscured by the cellular membrane which connects it to the sclerotic. The inner surface, which is in contact with the retina, presents a very different appearance. It is soft and smooth, and when minutely injected, resembles the more delicate mucous membranes, and exhibits a remarkable degree of minute villous vascu- larity. The external surface being composed of the larger branches of arteries, veins, and nerves, may be torn away from the soft, smooth, and more closely interwoven inner layer, or the inner layer may be partially dissected up from it, with some care, especially in the eyes of the larger quadrupeds. This manoeuvre having been executed by Ruysch, and prepara- tions so formed displayed by him, the inner layer has been denominated the tunica Ruys- chiana. But this is a mere anatomical artifice. There is no natural division into two layers, the soft, smooth, and highly vascular inner surface being formed by the ultimate subdivi- sion and distribution of the larger branches of vessels, which exhibit themselves sepaiately on the outside. It is a condition somewhat analo- gous to that of the skin, where the soft, smooth, villous external surface presents so remarkable a contrast to the rough internal surface with its layer of cellular membrane uniting it to the subjacent parts. ~->The choroid is supplied with blood from the ophthalmic artery by the short ciliary arteries, which penetrate the sclerotic at a short distance from the entrance of the optic nerve, and are distributed to it in nearly twenty small branches. These branches ramify and inosculate freely on the outside of the membrane, and are visible as distinct vessels, especially on the posterior part of the sphere. They finally terminate on the inner surface, forming a beautiful vascular expansion. The long ciliary arteries give scarcely any twig to the choroid, being distri- buted to the iris, and the anterior branches furnished to the sclerotic, as described in speaking of that membrane, do not penetrate to the choroid. The veins of the choroid pre- sent a peculiar appearance. The ramifications are arranged in the form of arches or portions of a circle, bending round to a common trunk like those of certain trees with pendulous branches. They discharge their blood into four or five larger branches which penetrate the sclerotic at nearly equal distances from each other behind the middle of the eyeball. On account of this peculiar arrangement they have received the name of vasa vorticosa. They lie external to the ciliary arteries, but the ultimate ramifications pervade the inner surface in the same manner as the arteries ; and if the venous System of the eye be minutely injected, the same beautiful uniform villous vascularity is displayed as in the arterial injections. The annexed figure is a copy of Zinn's re- presentation of the vasa vorticosa. Fig. 104. The numerous nerves which pierce the scle- rotic and run forward between that membrane and the choroid, called ciliary nerves, being distributed almost exclusively to the iris, are to be noticed when that organ is described ; small branches of them are, however, probably distributed to the choroid and its appendages, and possibly even to the retina and hyaloid membrane. The inner villous surface of the choroid, which in man is stained with the black pig- ment, in several other animals presents a bril- liant colour and metallic lustre. This is called the tapeturn. It is not a superadded material nor dependent on any imposed or separable colour- ing matter, but is merely a different condition of the surface of the choroid or tunica Ruvs- chiana, by means of which rays of light of a certain colour only are reflected. It exists in the form of a large irregular patch, occupying the bottom of the eye toward the outside of the entrance of the optic nerve. It is of a beautiful blue, green, or yellow colour, with splendid metallic lustre, and sometimes white as silver. It is not obscured by the black pigment which covers the rest of the surface and even encroaches a little on its margin, and consequently it acts most perfectly as a concave reflector, causing the rays of light previously concentrated on the bottom of the eye by the lens to be returned, and to produce that re- markable luminous appearance observed in the eyes of cats and other animals when seen in obscure situations. This provision is, absent m man, the quadrumanous animals, bats, the insectivorous order, perhaps all the rodentia, the sloths and many other of the class mammalia ; while it is present in the majority if not all of the ruminants, as well as in the horse, the cetacea, and most of the carnivorous tribe. -It does not appear to exist in birds or reptiles, and is absent in the osseous, although present in the cartilaginous fishes. I must here, how- ever, state that I am obliged to speak loosely respecting this matter, as the subject has not yet been thoroughly investigated. The use of this tapetum has not been ascertained, or the reason why it exists in some and is absent in other animals explained. It is obvious that where it is present the rays of light are trans- mitted through the retina, and again when reflected by the tapetum are returned through the same retina, thus twice pervading that structure. k 2 180 EYE. On the outside and anterior part of the choroid, where the margin of that membrane corresponds to the place of union between the sclerotic and cornea, a peculiar and distinct formation exists apparently for the purpose of securing a firm union between the two mem- branes. It is commonly called the ciliary liga- ment, also orbiculus ciliaris, circulus ciliaris, by Lieutaud plexus ciliaris, by Zinn armulus cellulosus, and by Sommerring gangliform ring. It is a gray circle of soft cellular membrane about two lines broad, applied like a band round the margin of the aperture into which the iris is fitted. It adheres closely to the choroid, and almost equally closely to the scle- rotic, especially in the groove where the cornea joins that membrane. It contains few red vessels, and is not stained by the black pig- ment; consequently it is of a whitish colour. The ciliary nerves penetrate it and subdivide in its structure. Hence it has been considered by Sommerring as a ganglion, aftd had been previously described by Lieutaud as a nervous plexus. The ciliary nerves, however, merely pass through, and may easily be traced on to the iris. It is evidently a mere band of cellular membrane serving to bind the choroid and sclerotic together at this point, and is obviously a provision essentially necessary for the perfec- tion of the anatomical mechanism of the eye, as without it the aqueous humour must, from pressure on the eyeball, be forced back be- tween the two membranes. In man it is broader in proportion than in the larger quadrupeds, and in birds it is particularly large and dense, adhering more closely to the circle of osseous plates than to the choroid, and consequently presents a very remarkable appearance when the latter membrane is pulled off with the ciliary processes and iris, an appearance to which the attention of anatomists was first drawn by Mr. Crampton. From its position and appearance the ciliary ligament has often been suspected to be a muscular organ, destined by its contraction to alter the form of the cornea, and thus adapt the eye to distance. There is not, however, sufficient evidence to sustain such an opinion. The plate introduced to represent the ciliary nerves, as well as that which represents the iris, exhibit this part of the organization of the eyeball in connexion with the choroid. On the inside of the choroid, surrounding the aperture into which the iris is fitted, and corresponding in position within to the ciliary ligament without, exists another peculiar pro- vision destined to establish a connexion between this part and the hyaloid membrane of the vitreous humour, as the ciliary ligament esta- blishes a similar connexion between the sclerotic and choroid. This is the corpus ciliare or ciliary processes, called sometimes incorrectly ciliary ligament, and by Sommerring corona ciliaris. It is composed of a number of dis- tinct folds or productions of the choroid, having their anterior extremities extended to the back of the iris, while the posterior gradually dimi- nish until lost in the membrane from which they originate. Each fold or ciliary process is a production or continuation of the choroid, and cannot be separated from it unless clipped off by the scissors. They appear to be com- posed altogether of a remarkable interlacement of arteries and veins derived from those of the choroid, and exhibit no appearance whatsoever of muscular organization, although considered by Porterfield and others as endowed with that function. These are sixty or seventy in num- ber, fifty-seven being enumerated by Sommer- ring, and seventy by Zinn. They are about two lines in length, but are not equally so, every alternate one being shorter than the next to it. The free internal margin of each ciliary process is buried in the hyaloid membrane of the vitreous humour at its anterior part, round the circumference of the crystalline lens, and a corresponding production of the hyaloid mem- brane projects into the space between these processes so as to establish a most perfect bond of union between the two structures. The ciliary processes appear to be attached to the circumference of the lens, and are often de- scribed as having such connexion. This, how- ever, is not the case. The anterior extremities do not touch the circumference of the lens; they project into the posterior chamber of the aqueous humour up to the back of the iris, and consequently constitute the circumferen- tial boundary of that cavity. When the eye becomes flaccid from evaporation after death, the ciliary processes fall down to the margin of the lens and appear to adhere ; but if the cornea and iris be removed from the eye of a subject recently dead, a circle of hyaloid membrane may distinctly be seen occupying the space between the ciliary processes and lens, through which the observer can see to the bottom of the eye. This space is represented and pointed out in Sommemug's plates. The annexed figure from Zinn's work represents the corpus ciliare or circle of ciliary processes on a large scale. Fig. 105. The choroid, in common with several other parts of the eye and its appendages, is stained by a black colouring matter secreted in and upon different textures. In man it is of a dark- brown colour, but in other animals is generally EYE. 181 black, and so loosely connected with the struc- ture in which it is deposited, that in dissecting the eyes of our common graminivorous animals under waterit becomes diffused, and colours the fluid as the ink of the cuttle-fish obscures the water into which it is shed. It is not confined to any one particular structure, but is deposited in every situation where it is necessary for the purpose for which it is destined. It is found in considerable quantity on the inner surface of the choroid, where it appears as if laid on in the form of a paint, and is frequently so described ; but it is much more probable that it is deposited in the interstices of the exqui- sitely fine cellular membrane which connects the choroid with the delicate covering of the retina. In this situation it often, especially in infants, presents the appearance of a perfectly distinct black membrane, which may be peeled off in flakes or allowed to remain on the retina in patches, as noticed by Haller. It also per- vades the structure of the choroid, at least in the adult, and even stains the inner surface of the sclerotic and the cellular layer which con- nects these two membranes. It is deposited in larger quantity in the ciliary processes and upon the back and in the texture of the iris. In many animals it is found forming a black ring round the margin of the cornea and in the edge of the third eye-lid, as well as in the pecten or marsupium nigrum in birds. It is even sometimes found scattered, as if acci- dentally, as in the texture of the sclerotic in hogs, and within the sheaths of the optic nerve in oxen; it is obvious that it does not require any special form of organization for its produc- tion, but is merely secreted into the cellular membrane, where necessary, as the colouring matter is secreted with cuticle on the skin. It is darker in the earlier periods of life, and in the infant is more confined to the inner sur- face of the choroid and to the posterior surface of the iris, than pervading the texture of either of these membranes. In old age it evidently fades, and even appears as if absorbed in patches. It is sometimes altogether absent, as in those animals called albinos, where all the parts usually coloured are unstained. Its use is obviously to prevent the rays of light from being reflected from surfaces where they should be absorbed, a provision as essential to the perfection of the animal eye as to the artificial optical instrument. It is also applied to give complete opacity to prevent the transmission of light, and hence is deposited in large quantity in and on the iris, as well as in the ciliary pro- cesses which correspond in situation to the exposed part of the sclerotic, through which the light might otherwise pass to the bottom of the eye, and disturb correct vision. The layer of black pigment on the inner surface of the choroid has undergone a careful microscopic investigation, especially by Mr. T. W. Jones, the results of which are stated in a short account of the anatomy of the eye prefixed to the second edition of Mr. M'Kenzie's work on Diseases of the Eye: He says that it possesses organization and constitutes a real membrane, and when examined with the raiscroseope " is 106. seen to consist of very minute flat bodies of a hexagonal form, joined together at their edges. These bodies, which are about ^th of an inch in diameter, consist of a central transparent nucleus, surrounded by an envelope of colour- ing matter, which is most accumulated at their edges The centre, indeed, of each hexa- gonal plate is a transparent point, and appears somewhat elevated, the elevations on the inner surface corresponding to depressions to be described in the membrane of Jacob. That part of the membrane of the pigment situated on the pars mm plicata of the ciliary body around the ciliary processes, and on the poste- rior surface of the iris, is composed of irregu- larly rounded bodies, analogous to the hexa- gonal plates. In albinos the same membrane exists, but contains no pigment. The bodies composing it are but little deve- loped, being nothing but the central nuclei separated from each other by large intervals, and not hexagonal, but circular, or even globular." The annexed figure represents this mem- brane of the pigment as described. Sometimes the black pigment is totally or partially deficient, not only in inferior animals, but also in man, constituting the variety deno- minated albino, of which the white rabbit affords a good example. The circumstance lias attracted considerable attention, and has been the subject of particular observation by Mr. Hunter, Blumenbach, and many others. Dr. Sachs has given a curiously elaborate account of himself and his sister, who are botli albinos. The eye in such cases appears of a beauti- fully brilliant red, in consequence of the blood being seen circulating through the transparent textures unobscured by the pigment, but the individual suffers from the defect in conse- quence of the light being transmitted through all the exposed part of the organ ; proving that the covering of black pigment is deposited on the back of the iris and in the ciliary pro- cesses to obviate this injurious consequence. In human albinos the eyes have often a tremu- lous oscillating motion, and the individual is unable to bear strong light. The colour of the black pigment does not ap- pear to depend on the presence of carbon or other dark material, and the minute quantity of oxide of iron contained in it is obviously insufficient for the production of so deep a tint. It is insoluble in water, either hot or cold, or in dilute sulphuric acid ; but strong nitric or sulphuric acids decompose it, and are decom- posed by it. Caustic potash is said to dissolve it, though with difficulty, but as ammonia is evolved during the process, and the nature of the pigment necessarily altered, it cannot be considered a case of simple solution. By destructive distillation it affords an empyreu- rcatic oil, inflammable gases, and carbonate of ammonia. It is, therefore, obviously an anw mal principle siii generis, its elements being oxygen, hydrogen, carbon, and nitrogen. One hundred parts in a dry state leave, when incinerated, 4.46 of acalx, consisting of chlo- ride of calcium, carbonate of hme, phosphate 182 EYE. of lime, and peroxide of iron. For these par- ticulars I am indebted to Dr. Apjohn. Of the iris. — This is the circular partition or screen interposed between the cornea and crys- talline lens, filling up the aperture in the ante- rior part of the sphere of the choroid, and conse- quently exactly fitted to the place of union of the ciliary ligament and choroid with the sclerotic round the cornea. It has an aperture in the centre called the pupil, through which the central portion of the pencil of rays incident upon the cornea is transmitted, while the extreme rays are intercepted ; and appears to answer the same purpose as the diaphragm or eye-stop in the telescope, but with this advantage, that it is enlarged or diminished according to the quantity of light, the distance of objects, or even the will of the individual. The iris is frequently called uvea, a term also applied to the spherical choroid ; or the anterior part is called iris, and the posterior uvea. To avoid confusion the term should be discarded alto- gether, and that of iris alone retained to designate this important part of the organ. The surface of the iris is flat or plane, al- though it appears convex when seen through the cornea, or when in dissecting the eye it falls on the convex surface of the crystalline lens. It is remarkable that the aperture or pupil is not exactly in the centre of the disc, but a little towards the inside. The anterior surface presents a very peculiar and remarkable appearance, evidently not depending on or arising from vascular ramifications or nervous distribution. This appearance is described with precision and accuracy both by Zinn and Haller, although unnoticed or only briefly al- luded to in many of the slovenly compilations which have appeared since they wrote. It is, however, described by Meckel, who saw what he describes, and read what he quotes. Haller's words are as follow : — " In anteriori lamina iridis eminet natura flocculenta, vane in flam- mulas quasdam introrsum euntes disposita, quibus aliqua est similitudo rotundorum ar- cuum, ad centrum pupilla; convexorum. Qui- vis flocculus est serpentinarum striarum intror- sum convergentium, et intermistarum macu- larum fuscarum congeries : conjuncti vero flocculenti fasciculi arcuin quasi serratum, emi- nentem, ad aliquam a pupilla distantiam effi- ciunt, qui convexus eminet, quasi antrorsum, suprareliquum planum pupilleeelatus. Fabricse pulchritudinem nulla icon expressit." (Ele- menta Physiologic, torn. v. p. 369.) Zinn's description is equally accurate and precise. In the 12th volume of the Medico-Chirurgical Transactions I have noticed this structure m the following words : " If the iris be attentively examined in the living subject, or under water after the cornea has been removed, a number of irregularly shaped masses may be seen pro- jecting from the middle space between the circumference and the pupil. From the con- vexities of these masses, a number of elevated lines, equally irregular in size and number, proceed toward the pupil, and attach them- selves at the distance of about a twentieth pait of ah inch from its margin, and from this point of attachment a number of much smaller stria converge to the edge of the central open- ing. It is quite impossible for words to give an adequate idea of this appearance. If I ventured to compare it with any other with which I am acquainted, I should say that it resembled strongly the carnea columns and cordce tendinea of the heart, both in form, arrangement, and irregularity of conformation. This structure is more strongly marked in the hazel than in the blue iris ; and in many cases the fleshy projections coalesce, by which they appear less distinct ; but the loops or cords which arise from them always exist, and often project so much from the plane of the iris as to admit of having a small probe or bristle passed beneath them. That this appearance of the iris does not depend on any particular disposition of its vessels, i6, I think, obvious, from the thickness of these cords or stric being so much greater than the vessels of the iris, from their being arranged in a manner altogether different from vascular inosculation, and finally, because the iris when successfully injected and expanded does not present that interlacement of branches surrounding the pupil which has so often been described from observation of its uninjected state." The anterior surface of the iris is of a light blue colour in persons of fair skin and light hair, of a blue grey in others, sometimes of a mixture of tints called a hazel iris ; and in negroes and others, where the skin is stained by the usual colouring matter, the iris is of a deep brown, and is commonly described as a black eye, being pervaded by the black pigment throughout its texture, as well as coated with it on its posterior surface. In animals altogether destitute of the usual colouring matter on the surface, called albinos, the iris has no other colour than that of the blood which circulates in its vessels. The annexed engraving is a copy of a most accu- rately executed representation of the face of the iris, shewing the cameo1 columna and corda tendinea much magnified. Fig. 107. The posterior surface of the iris is as remark- able as the anterior, but altogether different in its nature. 1 have given the following des- cription of it in the paper to which I allude in EYE. 183 the Medico-Chirurgical Transactions. " In order to obtain a correct view of the posterior surface of the iris, a transverse vertical section of the eye should be made at the distance of about an eighth of an inch behind the cornea, and the lens, and portion of vitreous humour attached to it, removed : the iris now appears covered by a thick layer of black pigment, marked by a number of converging lines ; these lines on close inspection are found to be channels or hollows, as if resulting from a puckering or folding of the membrane. The pigment is secured from being detached, and diffused in the aqueous humour, by a fine transparent membrane, which is closely attached to the margin of the pupil, from whence it is continued over the back of the iris, and anterior extremities of the ciliary processes, to the cir- cumference of the lens, over the front of the • capsule of which it is also probably extended, if it be, as may be supposed, the membrane of the aqueous humour. This delicate membrane may be turned down by the point of a needle ; as it is connected to the iris by loose cellular structure only, in the interstices of which the black pigment is deposited. It is at first black, but by gentle agitation in water the colouring matter is removed, and the membrane remains transparent. When the membrane and pig- ment have been removed, the back of the iris appears free from colour, and marked by a number of delicate elevated folds, converging from the ciliary processes to within a short distance of the pupil ; they are permanent and essential, and seem of the same nature as the ciliary processes. The pupil is immediately surrounded by a well-defined distinct circle, about the twentieth part of an inch in diameter, of a denser structure than the rest of the iris : this is what has been long described as the orbicular muscle, or constrictor of the pupil. If the iris be treated, as I before mentioned, by maceration and extension, this appearance still preserves its integrity, and retains its original character." Haller and Zinn describe these converging radiating folds, but the former de- nies the existence of the circular arrangement round the margin of the pupil, of the presence of which I do not entertain the slightest doubt, but which is sometimes so slightly marked, that I am not surprized to find its existence doubted if the part has not been examined in a variety of examples. This circle, or orbicular muscle, is sometimes equally visible on the anterior surface, but is generally obscured by the converging cords above described. The folds or elevations on the back of the iris, con- verging toward the pupil, have been considered the muscular agents for dilating the pupil, but if examined in the eyes of the larger quadru- peds, it is obvious that they are destined to give this part of the organ the requisite degree of opacity, and to afford an appropriate place for the deposit of the black pigment, in this res- pect closely resembling the ciliary processes, and the pecten in the eye of birds, so much so, that I think they might be appropriately called the ciliary processes of the iris. The iris is most plentifully supplied with bloodvessels and nerves. The two long ciliary arteries which penetrate the sclerotic posteri- orly advance horizontally, about the middle of the eyeball, between that membrane and the choriod, to the iris, where each divides into two branches, which proceed round the circumfer- ence and inosculate with each other, thus form- ing an arterial circle, from which numberless branches converge to the pupil. Much impor- tance has been attached by anatomists to the manner in which these radiating vessels are disposed, in consequence of the representation of Ruysch, who exhibited them as forming a series of inosculations at a short distance from the pupil, since called the lesser circle of the iris. I do not deny that the vessels of the iris inosculate as in other parts of the body, but I do not believe that they present this very re- markable appearance, and I suspect that Ruysch exaggerated what he had seen, or de- scribed from an iris in which the injection had been extravasated and entangled in the tendi- nous cords, which I have described as extend- ing from the fleshy bodies to the margin of the pupil. The question is fortunately of no importance. It is sufficient to know that the organ is amply supplied with arterial blood. The iris is plentifully furnished with nerves : they are derived from the third and fifth pairs, with communications from the sym- pathetic, and consequently having connexions with the sixjth. They penetrate the sclerotic posteriorly, and advance towards the iris be- tween the sclerotic and choroid, about fifteen or twenty in number : arrived at the ciliary ligament, they divide at acute angles, and may be traced through this structure until they are finally lost in the iris, as seen in the annexed figure. Fig. 108. From the foregoing description, it appears that the iris is eminently distinguished for the perfection of its organization ; and endowed as it is with the power of enlarging or diminishing the aperture in its centre, there can be little doubt that it is a beautiful application of mus- cular structure and function to the perfection of this most elaborately constructed organ. The authority of Haller operates to the pre- sent day to throw a doubt upon the muscula- rity of the iris ; but Haller, strange as it may appear, was not correctly informed in many particulars respecting this structure. He de- nies the existence of the orbicular muscle ; he doubts the irritability of the organ, and he even 184 EYE. considers it destitute of sensibility, and as- sumes that the pupil is dilated after death. Any anatomist may, however, demonstrate the orbicular muscle; any surgeon breaking up a cataract, may elicit the irritability, and see the pupil contract, as the fragments of the lens or the side of the needle touch its margin. The pain produced by pinching or cutting the iris in operations for cataract and artificial pupil is no longer matter of doubt, and the assumption that the pupil dilates when death takes place is disproved by daily observation. The pupd contracts to exclude light when too abundant, and dilates to admit it when deficient in quan- tity ; the heart contracts to expel the blood, and dilates to receive it; the diaphragm con- tracts to fill the lungs, and relaxes to assist in emptying them. I can see no material differ- ence between the phenomena exhibited by the actions of the iris, and those displayed by the muscular system generally. I believe that when the pupil contracts to intercept light, that con- traction is accomplished by the orbicular mus- cle, which operates as any other sphincter ; and that when the pupil is dilated to admit light, the dilatation is accomplished by the con- traction of the structure, which I have said re- sembles the carnea columnm and corda tendinea in the heart. During foetal life the aperture in the centre is closed by a membrane, hence technically called membrana pupi/laris. The discovery of this membrane was first announced by VVachendorf, but was subsequently claimed by Albinus, and still later by Dr. Hunter for a person of the name of Sandys. It is usually described as existing from the earliest period of fatal life to the seventh month, when it disappears. In the paper communicated by me to the Medico- Chirurgical Society, I have endeavoured to shew that this description is not correct, but that this membrane continues to the ninth month. The account there given is as follows : " If the eye be examined about the fifth month, the membrana papillaris is found in great perfec- tion, extended across a very large pupil ; the vessels presenting that singular looped arrange- ment, (with a small irregular transparent por- tion in the centre,) well depicted by Wrisberg, Blumenbach, Albinus, Sommerring, Cloquet, and others. About the sixth month it is equally perfect; the pupil is however smaller, the iris being more developed. Subsequently to this date the vessels begin to diminish in size and number, and a larger transparent portion occu- pies the centre. At the approach of the eighth month, a few vessels cross the pupil, or ramify through the membrane at a short distance from the margin, without at all presenting the looped appearance of the previous period, but ad- muting a free communication between the ves- sels of the opposite side of the iris. The pupil is now still more diminished in size, and the iris has assumed its characteristic coloured ap- pearance; notwithstanding the absence of ves- sels, the membrane still preserves its integrity, though perfectly transparent. The period now approaches when it is to disappear; this occur- rence takes place, according to my observations, a short time previous or subsequent to birth. In every instance where I have made the exa- mination, I have found the membrana papillaris existing in a greater or less degree of perfection in the new-born infant; frequently perfect without the smallest breach, sometimes pre- senting ragged apertures in several places, and, in other instances, nothing existing but a rem- nant hanging across the pupil like a cobweb. I have even succeeded in injecting a single ves- sel in the membrana papillaris of the ninth month. Where I have examined it in subjects who have lived for a week or fortnight after birth, as proved by the umbilicus being healed, I have uniformly found a few shreds still re- maining. It is obvious from the preceding observations, that the membrane does not dis- appear by a rent taking place in the centre, and retraction of the vessels to the iris, as sup- posed by Blumenbach, but that it at first loses its vascularity, then becomes exceedingly thin and delicate, and is finally absorbed. The de- monstration of what I have advanced respect- ing this delicate part is attended with much difficulty, and requires great patience. The display of the membrana papillaris of the seventh month is comparatively easy ; but at the ninth month, or subsequently, it can only be accom- plished by particular management. The eye, together with the appendages, should be care- fully removed from the head ; it should then be freed from all extraneous parts by the scis- sors, under water, and a careful section made at a short distance behind the cornea; taking care to include the vitreous humour in the divi- sion, in order that the lens may remain in its proper situation. The portion to be examined should now be removed into a shallow vessel of water, to the bottom of which a piece of wax has been secured. The operator should be provided with fine dissecting forceps and nee- dles in light handles; with one needle he should pin the sclerotic down to the wax, and with the other raise the lens, and portion of vitreous humour attached to it, from the ciliary processes, and separate the ciliary ligament from the sclerotic. He may now expect to dis- cover the membrana pupillaris, but its perfect transparency renders it completely invisible ; he may, however, ascertain the existence, by taking a minute particle of the retina and dropping it into the centre of the pupil, where it remains suspended if this membrane exist. The preparation should now be taken up in a watch-glass, and placed in a weak mix- ture of spirit and water, and a little pow- dered alum raised on the point of a needle dropped upon it. After a day or two it may be examined; and if the membrane be pre- sent, it has become sufficiently opaque to be visible, and may now be suspended in a bottle of very dilute spirit." In the annexed engravings, A represents the membrana pu- pillaris of about the fifth month, present- ing the peculiar looped arrangement of the vessels. B represents the membrane about the eighth month, not presenting the looped ar- rangement. C represents the membrane with a red vessel in its structure at the ninth month. D EYE. 185 shews a few shreds of the membrane remaining a week or more after birth. Fig. 109. The pupil is closed by this membrane during foetal life in order to preserve its dimensions, and secure a correct growth of the iris while the organ is in darkness. If the membrane disap- peared about the seventh month, the pupil should become dilated and remain so during the two succeeding months, unless the muscu- lar power be undeveloped, which is not proba- ble, as it may be seen to operate shortly after birth. Of the retina. — This is the third spheri- cally disposed membrane entering into the structure of the eye, and may be considered the most essential of all, being that which is endowed with the peculiar description of sensibility which renders the individual con- scious of the presence of light. It is as exactly fitted to the inside of the choroid as that membrane is to the sclerotic, but does not extend to the anterior margin of the choroid as that structure extends to the anterior margin of the sclerotic. The retina is destined to be penetrated by the rays of light, which, reflected from surrounding objects, are collected to form images on the bottom of the eye, consequently its extension as far forward as the choroid or sclerotic is unnecessary, and nature makes no- thing superfluous. It is discontinued at the posterior extremities of the ciliary processes of the choroid, at the distance of about an eighth of an inch from the anterior margin of that membrane. The retina is evidently the optic nerve ex- panded in the bottom of the eye in the form of a segment of a sphere. That nerve differs, in some respects, in construction from the other nerves of the body. In its course from the hole in the bone through which it enters the orbit until it enters the eye, it is of a cylindrical form, and proceeds in a waving line to its desti- nation. The medullary fibres are involved in a tough strong material, not separable into cords or bundles as in other nerves, but constituting a cylinder of collected tubes, from the divided extremity of which the medullary matter may be squeezed in as soft and pulpy a form as it exists in the brain. It is not easy to determine by anatomical investigation, whether the medullary material is disposed in tubes or in a cellular structure, but as that material is universally disposed in a fibrous form, both in brain and nerve, it is more than probable that it is so ar- ranged here. These cerebral fibres involved thus in a cylindrical bundle of tubes, techni- cally called neurilema by modern anatomists, is covered externally by a fine transparent membrane, adhering to it so closely that it re- quires some care to separate it; and this is again covered by a tube of strong fibrous mem- brane, the sheath of the optic nerve continued from the dura mater to the sclerotic, to which membrane it adheres so firmly, that it cannot be separated except by the knife. Formerly the sclerotic was considered to be a continuation of the dura mater, and much importance, in a pathological point of view, was attached to the circumstance, but although both structures are of the fibrous class, the sclerotic is very different in texture, and the adhesion between them is not more remarkable than any other of the numerous adhesions which occur between fi- brous membranes. Where the optic nerve enters the eye, it is contracted in diameter, as if a string had been tied round it, and then passes through a hole in the sclerotic, to which it adheres. When seen from the inside, after removing the retina and choroid, it appears in the form of a circu- lar spot, perforated with small holes, from which the medullary material may be expressed. This is the lamina cribrosa of Albinus, consi- dered to be a part of the sclerotic, but which is really nothing more than the terminating ex- tremity of the nerve. The optic nerve does not enter the eye in the centre of the globe, but ahout an eighth of an inch to the side of it, assuming the centre to correspond to the extremity of a line passing from the middle of the cornea, through the centre of the eyeball to its back. The nerve is generally described and represented as pro- jecting in the form of a round prominence, as it enters the eye ; but this is not, I believe, the state of the part dining life, but is produced by the contraction of the neurilema pressing out the medullary matter in this form. As the nerve enters the eye, it immediately expands into and constitutes the retina, the medullary fibres separating and spreading out on the sphe- rical vitreous humour. The expansion of the nerve in separate fibres cannot be distinctly seen in the human eye, but may be recognized with some care in the eye of the ox, and with- out difficulty in that of the hare and rabbit, where it divides into two bundles, as has been well described by Zinn in the Gottingen Com- mentaries. The retina does not consist of medullary or cerebral fibrous matter alone. As the brain has its pia mater and arachnoid membrane, and the nerve its neurilema, this nervous struc- ture has its appropriate provision for its sup- port and the distribution of its vessels. This is the vascular layer, first accurately described by Albinus. It is a delicate transparent mem- 186 EYE. brane, of such strength, that when detached, it may be moved about in water, and freely ex- amined without breaking. It adheres so firmly to the hyaloid membrane of the vitreous hu- mour in the fresh eye, that it cannot be sepa- rated entire, and the medullary fibres adhere so closely to its external surface, that they can- not be detached at all in the form of a distinct membrane. To demonstrate the vascular layer, the sclerotic should be carefully removed, leav- ing a portion of the optic nerve freed from its sheath ; the choroid should then also be re- moved under water, by tearing it asunder with a pair of forceps in each hand. The vitreous humour, covered by the retina only, should then be allowed to remain about two days in the water, at the end of which time the me- dullary layer softens and separates into flakes, which may be scraped from the vascular layer beneath by passing the edge of a knife gently over it, after which the vascular layer may be detached by careful management, and sus- pended in a bottle from the optic nerve. The retina is supplied with blood from the ophthalmic artery, a small branch of which penetrates the optic nerve at a short distance from the back of the eye, and proceeds through its centre until it arrives at the retina. The hole in the centre of the nerve, through which it passes, was formerly called the porus opticus. Arrived at the retina, the vessel, under the name of the central artery of the retina, divides into two branches, which surround the foramen of Sdmmerring, and sending ramifications in every direction, terminate by encircling the an- terior margin. Besides the branches which carry red blood, the central artery probably furnishes a transparent branch to the centre of the vitreous humour, as such a branch running on to the back of the crystalline lens, may be injected in the eye of the foetus, and a transpa- rent production from the central artery into the vitreous humour may be observed in the eyes of oxen and other large animals. The arteries of the retina supply the vitreous humour with blood, as no other source exists, except from the ciliary processes of the choroid, which, being buried in the hyaloid membrane, most probably furnish vessels to the anterior part, and in dissecting the vascular layer above de- scribed, in which the vessels ramify, it is found to adhere to the hyaloid membrane by points along the course of the vessels, which points, it is reasonable to believe, are small branches. As the medullary or cerebral fibres of the retina are sustained on the inside by the vascu- lar layer above described, they are also protected on the outside by another membrane, which separates them from the inner surface of the choroid. This is the membrane which I des- cribed in a communication in the Philosophical Transactions in 1819, and as I cannot give a more intelligible account of it than that there contained, I venture to introduce it here. " Anatomists describe the retina as consisting of two portions, the medullary expansion of the nerve, and a membranous or vascular layer. The former externally, next to the choroid coat, and the latter internally, next to the • vitreous humour. All, however, except Albinus and some of his disciples, agree, that the nervous layer cannot be separated so as to present the appearance of a distinct membrane, though it may be scraped off. leaving the vascular layer perfect. That the medullary expansion of the optic nerve is supported by a vascular layer, does not, I think, admit of doubt ; but it does not appear that Albinus was right in supposing that the nervous layer can be separated in form of a distinct membrane, though shreds of a considerable size may be detached, especially if hardened by acid or spirit. " Exclusive of these two layers, I find that the retina is covered on its external surface by a delicate transparent membrane, united to it by cellular substance and vessels. This struc- ture, not hitherto noticed by anatomists, I first observed in the spring of the last year, and have since so frequently demonstrated, as to leave no doubt on my mind of its existence as a distinct and perfect membrane, apparently of the same nature as that which lines serous cavi- ties. I cannot describe it better, than by detailing the method to be adopted for examining and dis- playing it. Having procured a human eye, within forty-eight hours after death, a thread should be passed through the layers of the cor- nea, by which the eye may be secured under water, by attaching it to a piece of wax, previ- ously fastened to the bottom of the vessel, the posterior half of the sclerotic having been first removed. With a pair of dissecting forceps in each hand, the choroid coat should be gently torn open and turned down. If the exposed surface be now carefully examined, an ex- perienced eye may perceive, that this is not the appearance usually presented by the retina ; instead of the blue-white reticulated surface of that membrane, a uniform villous structure, more or less tinged by the black pigment, pre- sents itself. If the extremity of the ivory handle of a dissecting knife be pushed against this surface, a breach is made in it, and a mem- brane of great delicacy may be separated and turned down in folds over the choroid coat, presenting the most beautiful specimen of a delicate tissue which the human body affords. If a small opening be made in the membrane, and the blunt end of a probe introduced be- neath, it may be separated throughout, without being turned down, remaining loose over the retina ; in which state if a small particle of paper or globule of air be introduced under it, it is raised so as to be seen against the light, and is thus displayed to great advantage ; or it is sometimes so strong as to support small glo- bules of quicksilver dropped between it and the retina, which renders its membranous na- ture still more evident. If a few drops of acid be added to the water after the membrane has been separated, it becomes opaque and much firmer, and may thus be preserved for several days, even without being immersed in spirit. " That it is not the nervous layer which I de- tach, is proved by the most superficial exa- mination; first, because it is impossible to separate that part of the retina, so as to present the appearance I mention ; and, secondly, be- EYE. 187 cause I leave the retina uninjured, and present- ing the appearance described by anatomists, especially the yellow spot of Soemmering, which is never seen to advantage until this membrane be removed : and hence it is that conformation, as well as the fibrous structure of the retina in some animals, become better marked from remaining some time in water, by which the membrane I speak of is de- tached. " The extent and connections of this mem- brane are sufficiently explained by saying, that it covers the retina from the optic nerve to the ciliary processes. To enter into farther inves- tigation on this subject would lead to a dis- cussion respecting the structure of the optic nerve, and the termination of the retina an- teriorly, to which it is my intention to return at a future period. "The appearance of this part I find to vary in the different classes of animals and in man, according to age and other circumstances. In the foetus of nine months it is exceedingly de- licate, and with difficulty displayed. In youth it is transparent, and scarcely tinged by the black pigment. In the adult it is firmer, and more deeply stained by the pigment, which sometimes adheres to it so closely as to colour it almost as deeply as the choroid coat itself; and to those who have seen it in this state, it must appear extraordinary that it should not have been before observed- In one subject, aged fifty, it possessed so great a degree of strength as to allow me to pass a probe under it, and thus convey the vitreous humour covered by it and the retina from one side of the basm to the other ; and in a younger subject I have seen it partially separated from the retina by an effused fluid. In the sheep, ox, horse, or any other individual of the class mammalia which I have had an opportunity of examining, it presents the same character as in man ; but is not so much tinged by the black pigment, adheres more firmly to the retina, is more uniform in its structure, and presents a more elegant appear- ance when turned down over the black choroid coat. In the bird it presents a rich yellow brown tint, and when raised, the blue retina presents it- self beneath ; in animals of this class, however, it is difficult to separate it to any extent, though I can detach it in small portions. In fishes, the struc- ture of this membrane is peculiar and curious. It has been already described as the medullary layer of the retina by Haller and L'uvier, but I think incorrectly, as it does not present any of the characters of nervous structure, and the retina is found perfect beneath it. If the scle- rotic coat be removed behind, with the choroid coat and gland so called, the black pigment is found resting upon, and attached to, a soft friable thick fleecy structure, which can only be detached in small portions, as it breaks when turned down in large quantity. Or if the cornea and iris be removed anteriorly, and the vitreous humour and lens withdrawn, the retina muy be pulled from the membrane, which re- mains attached to the choroid coat, its inner surlace not tinged by the black, pigment, but presenting a clear white, not unaptly compared by llaller to snow. " Besides being connected to the retina, I find that the membrane is also attached to the cho- roid coat, apparently by fine cellular substance and vessels ; but its connection with the retina being stronger, it generally remains attached to that membrane, though small portions are sometimes pulled off with the choroid coat. From this fact I think it follows, that the accounts hitherto given of the anatomy of these parts are incorrect. The best anatomists de- scribe the external surface of the retina as being merely in contact with the choroid coat, as the internal with the vitreous humour, but both totally unconnected by cellular mem- brane, or vessels, and even having a fluid secreted between them : some indeed speak loosely and generally of vessels passing from the choroid to the retina, but obviously not from actual observation, as I believe no one has ever seen vessels passing from the one membrane to the other. My observations lead me to conclude, that wherever the different parts of the eye are in contact, they are con- nected to each other by cellular substance, and, consequently, by vessels ; for I consider the failure of injections no proof of the want of vascularity in transparent and delicate parts, though some anatomists lay it down as a cri- terion. Undoubtedly the connection between these parts is exceedingly delicate, and, hence, is destroyed by the common method of ex- amining this organ ; but I think it is proved in the following way. I have before me the eye of a sheep killed this day, the cornea secured to a piece of wax fastened under water, and the posterior half of the sclerotic coat carefully removed. I thrust the point of the blade of a pair of sharp scissors through the choroid coat into the vitreous humour, to the depth of about an eighth of an inch, and divide all, so as to insulate a square portion of each membrane, leaving the edges free, and consequently no connection except by surface; yet the choroid does not recede from the mem- brane I describe, the membrane from the retina, nor the retina from the vitreous humour. I take the end of the portion of choroid in the forceps, turn it half down, and pass a pin through the edge, the weight of which is in- sufficient to pull it from its connection. I se- parate the membrane in like manner, but the retina I can scarcely detach from the vitreous humour, so strong is the connection. The same fact may be ascertained by making a transverse vertical section of the eye, removing the vitreous humour from the posterior seg- ment, and taking the retina in the forceps, pulling it gently from the choroid, when it will appear beyond a doubt that there is a connec- tion between them. " Let us contrast this account of the matter with the common one. The retina, a raein- biane of such delicacy, is described as being extended between the vitreous humour and choroid, from the optic nerve to the ciliary processes, being mere'y laid between them, 188 EYE. without any connection, and the medullary fibres in contact with a coloured mucus re- tained in its situation by its consistence alone. This account is totally at variance with the general laws of the animal economy ; in no instance have we parts, so dissimilar in nature, in actual contact: wherever contact without connection exists, each surface is covered by a membrane, from which a fluid is secreted; and wherever parts are united, it is by the medium of cellular membrane, of which se- rous membrane may be considered as a mo- dification. If the retina be merely in contact with the vitreous humour and choroid, we argue from analogy, that a cavity lined by serous membrane exists both on its internal and external surface : but this is not the fact. In the eye a distinction of parts was necessary, but to accomplish this a serous membrane was not required ; it is only demanded where great precision in the motion of parts was indis- pensable, as in the head, thorax, and abdo- men ; a single membrane, with the interpo- sition of cellular substance, answers the pur- pose here. By this explanation we surmount another difficulty, the unphilosophical idea of the colouring matter being laid on the choroid, and retained in its situation by its viscidity, is discarded; as it follows, if this account be correct, that it is secreted into the interstices of fine cellular membrane here, as it is upon the ciliary processes, back of the iris, and pecten, under the conjunctiva, round the cornea, and in the edge of the membrana nictitans and sheath of the optic nerve in many animals. Dissections are recorded where fluids have been found collected between the choroid and retina, by which the structure of the latter membrane was destroyed ; the ex- planation here given is. as sufficient to account for the existence of this fluid, as that which attributes it to the increased secretion of a serous membrane." The membrane is represented as it exists in the eye of the sheep, in the annexed figure, from my paper in the Medico-Chirurgical Transactions. Fig. Ill, Mr. Dalrymple, in his valuable work on the anatomy of the eye, takes a different view of the arrangement of this part of the retina : he says : — " From observations made on the human eye, in connection with other expe- riments on the eyes of animal, I am induced to consider it as a double reflected serous mem- brane. I was first led to take up this opinion in the year 1827, by the accidental observation of a very delicate membrane, which lined and was adherent to the entire choroid. Having minutely injected the eye of a sheep, I made a vertical transverse section through the sclero- tic, choroid, and retina, which last membrane, with Jacob's tunic, properly so called, and the vitreous body I removed. I then placed the remaining portion of the eye in dilute spirits of wine, intending to preserve it for the ex- hibition of the tapetum, which in this instance was remarkably beautiful. A few minutes after its immersion the tapetum lost to a con- siderable extent its brilliant hue, and I re- moved it from the glass to wash from its sur- face some deposit, which I thought might have obscured its polish. In doinjj this, how- ever, I detached a delicate membrane, mi- nutely filled with injection, and this membrane it was which on being placed in the spirit, became slightly opaque and produced the effect alluded to ; for the tapetum thus denuded in- stantly recovered, and still retains its bril- liancy." The inference that the membrane in ques- tion is a double reflected serous membrane is certainly more in conformity with analogy than the assumption that it is a single layer, but this uniformity in nature's operations has been too much insisted upon. I have above stated my reasons for considering it a single layer, and not a double serous membrane; and I should be inclined to think that the layer which Mr. Dal- rymple found adhering to the choroid was the membrane itself, which had not come away with the retina and vitreous humour, as 1 have found sometimes to happen, did not Mr. Dal- rymple further state that he has " in his pos- session a preparation, which does most dis- tinctly shew the double portions of this mem- brane ; one lining the choroid, the .other reflected over the pulpy structure of the retina." Mr. Jones, in the work formerly alluded to, gives the annexed representation of the mem- brane as it appears when Fig. Ml. highly magnified. Fig. 113 is a representation of the membrane by Mr. Bauer, magnified fifty diameters, from the Philosophical Transactions for 1822. In the centre of the retina, and consequently in the axis of vision, about an eighth of an inch from the entrance of the optic nerve, a very remarkable condition of structure exists. This is a small point destitute of cerebral or medullary fibres, appearing like a hole in the membrane, and hence called the foramen of Sommerring, from the distinguished anatomist who discovered it. This point is surrounded by a yellow margin, and the retina is here also puckered into a peculiar form of fold. Som- merring, in the Commentationes Societatis EYE. 189 Fig. 113. Regiee Gottingenses, gives the following account of the discovery. " On the 27th of January, 1791, while I examined the eyes of a very fine and healthy young man, a few hours previously drowned in the Rhine, being per- fectly fresh, transparent, and full, and sup- ported in an appropriate fluid, with the in- tention of exhibiting a perfect specimen of the retina to my pupils in the anatomical theatre, I so clearly detected in the posterior part of the retina, which was expanded without a single fold, on account of the perfect state of the eye, a round yellow spot, that I was convinced it was a natural appearance, and not a colour produced by any method of preparation. In examining this spot more accurately, I perceived in its centre a little hole occupying the situation of the true centre of the retina. With the same care I examined the other eye and found it exactly similar. I then communicated the discovery to my pupils in the public demonstrations." " In this precise spot, or in the very centre of the re- tina, is found an actual deficiency of the me- dullary layer, or a real hole perfectly round, with a defined margin a fourth of a line in diameter." " The transparent vitreous humour and black pigment are so clearly seen through this hole, that there can be no doubt that it is a real aperture, which being situated in the centre of the retina may be appro- priately termed the foramen centrule. Sur- rounding this J'oramen centrale the remark- able yellow colour resembling that of gum guita is so disposed that it appears much deeper toward the margin, and totally dis- appears at a distance of a line. This colour varies much according to the age of the individual, being very faint in infants, much deeper at puberty, on account of the thickness and whiteness of the retina at that period, appearing of a deep yellow brownish or crocus colour. In more ad- vanced age the colour is less intense, prin- cipally on account of the diminished whiteness of the retina, which also appears extenuated at that period. Even the choroid, where it corresponds to this fora- men, sometimes appears a little deeper- coloured." In the paper above alluded to, published in the Medico-Chirurgical Transactions, I have given the result of some careful in- quiries into the structure of this part, from which the following observations are ex- tracted. " Sommerring describes it as a hole in the retina with a yellow margin, mentioning as accidental a fold which occupies the situation of this hole and tends to conceal it, and thus accounting for its remaining so long unnoticed. This appearance is so constant and remarkable, that its existence may be very rationally considered essential to correct vision, and it therefore becomes an interesting object of speculation. The circumstances which it seems important to ascertain, are, whe- ther it is actually a hole in the retina with a yellow margin ; whether, in addition to this hole, the retina is folded or puckered in at this part ; or whether the appearance of a hole arises from a deficiency of the medullary layer of the retina without any orifice in its vascular layer. Both Sommerring himself and many others seem to consider that the fold is accidental and the consequences of changes occurring after death. It is here necessary to call to mind what those changes are with respect to the retina. If the eye had become flaccid previous to dissection, the retina on being exposed presents an irre- gular surface, arising from a number of folds diverging from the optic nerve as from a centre, and evidently produced by the loss of support from the partial evaporation of the fluid of the vitreous humour. These folds, however, never observe any regular form, or preserve precise situations, and may be obliterated by changing the position of the eye in the water. They disappear altogether after the part has remained some time in water, in consequence of the vitreous humour becoming again distended from imbibing the fluid in which it is im- mersed. It however requires no very great care or experience to distinguish between those accidental folds and the peculiar one in ques- tion. tlf the examination be made from with- out, removing the sclerotic and choroid behind, 190 EYE. the retina appears to be forced or drawn at tins point into the vitreous humour to the depth of about a twelfth of an inch, the entire fold being something more than an eighth in length. At first there is little or no appearance of a hole, but after the eye has remained for some time in the water, the fold begins to give way, and a small slit makes its appearance, which gradually widens, and assumes the appearance of a round hole. This hole is large in pro- portion to the degree to which the fold has yielded ; and when the fold totally disappears, as it sometimes does, the transparent point gives the appearance which Sommerring re- presents, of a hole with a yellow margin. If, instead of making the examination in this way from the outside, we view this part through the vitreous humour, the appearance of the hole is more remarkable ; but still that part of the retina is evidently projected forward be- yond the level of the rest of that membrane. In the eye of a young man, which I had an opportunity of examining under peculiarly favourable circumstances, within five hours after death, I noticed the following appear- ances. The cornea and iris having been cut away, and the lens removed from its situation, I placed the part in water, beneath one of the globular glasses, and held it so as to allow the strong light of a mid-day sun to fall directly upon it ; when the retina to the outside of the optic nerve presented unequivocally the ap- pearance of being drawn or folded into the form of a cross or star, with a dark speck in the centre, surrounded by a pale yellow areola. I further satisfied myself of the prominence of the fold by holding a needle opposite to it, while the light shone full upon it, a shadow being thus cast upon the retina which deviated from the straight line when passed over the situation of the fold. To ascertain whether there is actually a hole in the retina, or merely a deficiency of nervous matter at this point, 1 allowed the eye to remain for some days in water, until the connexions of the parts began to give way. I then introduced a small probe between the retina and vitreous humour, the part still remaining in water, and bringing the blunt point of the instrument opposite the transparent spot, attempted to pass it through, but found I could not do so without force sufficient to tear the membrane. I also re- moved the nervous matter by maceration and agitation in water, and on floating the vascular layer, found that I could no longer ascertain where the spot had originally existed, there being no hole in the situation previously occu- pied by the transparent speck." It is remarkable that the foramen of Sommer- ring has not been found in the eyes of any of the mammalia except those of the quudrumanu, in some of whom it lias been detected by Home, Cuvier, and others, but the extent to which it may be traced in this tribe has not been satis- factorily ascertained. Dr. Knox, in a paper in the Memoirs of the Wernerian Natural History Society, announces the discovery of its existence in certain lizards. In the lacerta superciliosa he says, " the retina is very thick, and somewhat firm and opaque. Where the optic nerve enters the interior of the eye-ball, there is a distinct marsupium or black circular body, proceeding- forwards apparently through the centre of the vitreous humour. Anteriorly, somewhat supe- riorly and towards the mesial line or plane, we perceive, on looking over the surface of the retina which regards the vitreous humour, a comparatively large transparent, nearly circular spot, through which may be distinguished the dark-coloured choroid. Close to this is gene- rally placed a fold or reduplication of the retina, which is in general remarkably distinct. This fold or folds, (for there are more than one) either proceed from the transparent point towards the insertion of the optic nerve, or close to it. Sometimes the fold seems, as it were, to lie over the transparent point, and partly to conceal it from view ; or the point is formed in the edge of the fold itself, as in apes, but in general the fold runs directly from the insertion of the optic nerve upwards and inwards, pressing very close to the edge of the foramen centrale." The foramen was also seen in the lacerta striata, lacerta calotes, and others, while it was not to be detected in the gecko, crocodile, and some others. It was also subsequently discovered in the chameleon. The annexed figures represent the foramen of Sommerring in the human eye. A, shews the retina expanded over the vitreous humour : on the right is the place from which the optic nerve was cut away, and from which the ves- sels branch out : on the left is \he foramen of Sommerring, represented by a black dot sur- rounded by a dark shade. B, shews the retina with a portion of the optic nerve. The exter- nal membrane is turned down as in the pre- ceding representation of the same structure in the sheep's eye, and the foramen of Sommer- ring, instead of a distinct hole, presents the appearance of a fold or depression with elevated sides. The wood-engraving does not admit of the delicacy of finish necessary to express per- fectly this condition of the part. Fig.WA. A. B. There is no part of the anatomy of the eye respecting which there has been so much diver- sity of opinion as the anterior termination of the retina. It has already been stated that it extends to the posterior extremities of the ciliary processes, where it is discontinued, pre- senting an undulating edge corresponding to the indented margin of this part of the corpus ciliare. Some assert that it extends to the mar- gin of the lens, others that it is the vascular EYE. 191 layer only which extends so far, and others that the vascular layer extends over the lens. No one however at present, who describes from observation, denies the termination of the ner- vous layer at the posterior margin of the ciliary body, although many insist upon the extension of the vascular layer to the circumference of the lens. The subject has received more attention „than it deserves, as it involves no consideration of importance, either physiological or anato- mical ; but I am convinced from a very care- ful scrutiny that no such layer extends between the ciliary processes of the choroid and those of the hyaloid membrane ; these two parts being mutually inserted into each other, as will pre- sently be explained. In the paper above quoted in the Medico-Chirurgical Transactions 1 have explained what appears to me to be the arrangement of this part in the following words : " On removing the choroid, ciliary processes, and iris, we see the retina terminating with a denned dentated margin, about a quarter of an inch from the circumference of the lens : be- tween this line of termination and the lens, the vitreous humour retains upon its surface part of the black pigment which covered the ciliary processes. If the eye be examined shortly after death, removing the black pigment from this part of the vitreous humour with a camel- hair pencil, there is an appearance of, at least, the vascular layer being continued to the lens ; this part not being so transparent as the rest of the hyaloid membrane, or so opaque as the retina. From such an examination 1 was led to con- clude that the vascular layer was continued to the margin of the lens, this part not being so transparent as the rest of the hyaloid membrane, or so opaque as the retina. From such an examination I was led to conclude that the vascular layer was continued to the margin of the lens, but I adopted a con- trary opinion after I had witnessed the change which took place when the part had remained twenty-four hours in water : the retina then separating with a slight force, and frequently detached by the disturbance given in making the examination. If, after removing the choroid without disturbing the retina, the part be al- lowed to remain in water for some days, the medullary part of the retina begins to give way, and may be altogether detached by agita- tion in water, leaving the vascular layer firmly attached at the line of termination just de- scribed. V\ ith all the care I could bestow, I have, however, never succeeded in separating this layer from the vitreous humour further. If the maceration be continued for a few days longer, the vascular layer of the retina gives way, the larger vessels alone remaining attached at the original line of termination of the retina, and appearing to enter the hyaloid membrane at this part ; the appearance which at first so much resembled the vascular layer proceeding towards the lens remaining unchanged, being in fact part of the vitreous humour itself. The circumstance which has most strengthened the notion of the retina being continued forward to the lens is, that often on raising the choroid and ciliary processes from the vitreous humour, we find those processes covered in several places by a fine semi-transparent membrane insinuated between the folds ; this is supposed to be the vascular layer of the retina, but is really the corresponding part of the hyaloid membrane which is torn up, being firmly united to this part of the choroid." After this article had been prepared for press, I received an admirable monograph upon the retina by B. C. It. Langenbeck, son of the celebrated professor of that name in the Uni- versity of Gottingen, in which the nature, structure, and relations of this most important and interesting part of the organ are subjected to a critical and elaborate inquiry. He advo- cates the membranous nature of the black pig- ment on the inner surface of the choroid, and gives an engraving of its organization as ascer- tained by the microscope, resembling that given from the essay of Mr. Jones in the preceding pages. He devotes several pages to the de- scription of the membrane which I found covering the medullary layer of the retina, and adds the testimony of a skilful anatomist in support of my description, sufficient to coun- terbalance the convenient scepticism of certain writers better skilled in making plausible books than difficult dissections. The fibrous struc- ture of the medullary layer of the retina is established, and a plate given of the peculiar nodulated condition of these fibres. The work concludes with an account of the morbid changes of structure observed in the retina, a subject which, notwithstanding its manfest importance, has not hitherto attracted the atten- tion which it deserves. I am indebted to Dr. Graves for the following abstract of some recent investigations of Treviranus on the same subject. " From microscopical examinations Treviranus demonstrates that the cerebral mass, both medullary and cortical, consists of hollow cylinders containing a soft matter. These cylinders, extremely minute in the cortical substance, are somewhat larger in the medul- lary, and still larger in the nerves. In the retina he finds, that after the optic nerve has penetrated the sclerotic and choroid, its cylin- ders or nervous tubes spread themselves out on every side either singly or collected into bundles, each cylinder or collection of tubes bending inwards through the vascular layer, and terminating in the form of a papilla on the vitreous humour." Of the vitreous humour. — It has already been stated that the globe of the eye is divided into two chambers by the iris, the posterior of which is distended by a spherical transparent mass called the vitreous humour, which does not completely fill this chamber between the back of the iris and the hollow sphere of the retina, but is discontinued or compressed at a short distance from the back of the iris, having a narrow space between it and that membrane, called the posterior chamber of the aqueous humour. This trans- parent mass is composed of water containing certain saline and animal ingredients, deposited in exquisitely delicate and perfectly transparent cellular membrane ; hence it is capable of sus- 192 EYE. taining its own weight and preserving its form when placed in water, and in air presents the appearance of a gelatinous mass, scarcely de- serving the name of solid. The cellular struc- ture, in which the watery fluid is lodged, has been called the hyaloid membrane, and the whole mass denominated the vitreous humour. The fluid of the vitreous humour, according to Berzelius, is composed of water, containing about one and a half per cent, of animal and saline ingredients; it has a saline taste, and acquires a slight opaline tint by being boiled. It consists of water 98.40, chloruret of soda with a little extractive matter 1.42, a substance solu- ble in water 0.02, and albumen 0.16. Its specific gravity is 1.059. When the hyaloid membrane is examined in its natural state, its cellular organization can scarcely be ascertained on account of its transparency ; but if it be suspended on the point of a pin until the fluid is allowed to drop out, it may be inflated with a fine blowpipe and dried, or if the whole be placed in strong spirit or weak acid, the mem- brane becomes opaque, and its organization obvious. It has been supposed that the cells in which the fluid is lodged present a determi- nate form, and attempts have been made to prove this by freezing the eye and examining the frozen fragments; but any one who has seen the hyaloid membrane rendered opaque by acid must allow that the cells are too minute to admit of such investigation, and that the frozen masses, supposed to be the contents of cells, are merely fragments of the hyaloid membrane with their contained fluid. Although the hyaloid membrane is perfectly transparent, and the red particles of the blood do not circu- late in its vessels, there can be little doubt that its growth and nutrition are effected by the circulation of a transparent fluid in vessels continuous with those conveying red blood. It is an established fact that transparent tex- tures which in a natural state do not exhibit a trace of coloured fluid, when excited or inflamed, become filled with red vessels, as may be seen in the conjunctiva. It is there- fore reasonable to admit that the hyaloid mem- brane does not present a deviation from this general law. The fluid of the vitreous humour, it is to be presumed from analogy, is secreted by the vessels of the hyaloid membrane, and if no red vessels can be detected, the secretion must be accomplished by transparent ones. It has already been stated that the vascular layer of the retina adheres to the surface of the vitreous humour, and that the points of adhe- sion are stronger along the course of the vessels than in the intermediate spaces ; it is therefore most probable that the more superficial part of the sphere is supplied with transparent blood from the arteries of the retina, while a branch directly from the central artery, as it penetrates the porus opticus, enters behind, and extends to the back of the lens : such a branch can be injected in the foetus, and is found to ramify on the back of the capsule of the lens ; and in the eyes of large quadrupeds a transparent production, probably vascular, has been ob- served proceeding from the entrance of the optic nerve into the mass of the vitreous humour. It is also probable that the ciliary processes of the choroid, which are buried in the hyaloid membrane anteriorly, supply blood to that part of the sphere. That the vitreous humour undergoes changes analogous to those which take place in textures supplied with red blood, is proved by its hyaloid membrane being found opaque and thickened in eyes which have been destroyed by internal inflam- mation. A total disorganization of the vitreous humour is a frequent occurrence, the hyaloid membrane losing its cohesion to such a degree that the fluid escapes from the eye as freely as the aqueous humour when the cornea is divided in the operation of extraction ; and after the lens and its capsule have been removed by operations with the needle, opacity of the hyaloid membrane is occasionally, although rarely, observed. Allusion has frequently been made in books to an appearance in the eye denominated glaucoma, attributed, rather vaguely, to opacity of the vitreous humour; it appears, however, to be nothing more than the usual opacity of the lens which occurs in advanced life, seen through a dilated pupil. As an additional proof of the vascularity of the vitreous humour may be adduced the fact, that in the eyes of sheep, injured by blows in driving to the shambles, the vitreous humour is deeply tinged with red blood. The spherical mass of vitreous humour, it has already been stated, is exactly fitted into and adheres to the inner surface of the retina. From the anterior termination of the retina to the posterior chamber of the aqueous humour, it is in contact with, and adhering to, the ciliary processes of the choroid. Where it is truncated or compressed on its anterior part to form the posterior chamber of the aqueous humour, it has the crystalline lens fitted into a depression in its centre, while a narrow circle of it appears between the circumference of the lens and the anterior extremities of the ciliary processes of the choroid, forming part of the boundaries of this chamber of aqueous humour. If the eye be allowed to remain for a day or two in water in order to destroy by maceration the delicate connexions between the hyaloid membrane and the choroid, and then the vitreous humour with the lens attached care- fully separated, the point of a fine blowpipe may be introduced under the surface of the hyaloid membrane at the circumference of the lens, and a series of cells' encircling the lens inflated. This is the canal of Petit, or canal godronne. It is thus described by the dis- coverer in the Histoire de l'Academie des Sciences for 1726. " I have discovered a small canal surrounding the crystalline, which I call the circular canal godronnd ; it can be seen only by inflating it, and when filled with air it forms itself into folds similar to the ornaments on silver plate, called for this reason Vaiselle godronne. It is formed by the doubling of the hyaloid membrane, which is contracted into cells at equal distances by little canals which traverse it, and which do not admit of the same degree of extension as the membrane, EYE. 193 which is very feeble; it thus becomes godronne. If the crystalline be removed from its capsule without injuring the membrane which forms this canal, these godronne folds are not formed by inflation or only in a very slight degree, but the canal becomes larger. It is in man commonly a line and aquarter, aline and a half ortwo lines in breadth, and not larger in the ox." An- nexed is a representation of this canal of Petit on a large scale. Fig. 115. Fig. 116. As the nature of the connection between the choroid and the hyaloid membrane, the formation of the posterior chamber of the aqueous humour, and the structure of this canal of Petit, have been the subject of contro- versy, I venture to introduce here an extract on this subject from the paper published by me in the Medico-Chirurgical Transactions. " If the sclerotic, choroid, iris, and retina be removed one or two days after death, leaving the vitreous humour with the lens embedded on its anterior part, we observe a number of stria on the vitreous humour, converging towards the circumference of the lens, cor- responding in number, size, and form to the ciliary processes, giving the same appearance collectively that the circle of ciliary processes or corpus ciliare does on the choroid, and nar- rowed towards the nasal side as the corpus ciliare is. This appearance has been noticed by most authors, but some describe it as arising merely from the marks left by the ciliary processes, while others consider these stria of the same nature as those productions of the choroid, and call them the ciliary pro- cesses of the vitreous humour ; it is the corona ciliaris of Camper and Ziun. If we remove the black pigment with a camel-hair pencil, we leave those productions on the vitreous humour more distinctly marked than when covered by the colouring matter, and presenting all the characters above stated, commencing behind with a well-defined margin, and terminating anteriorly by attachment to the capsule of the lens, the furrows between them capable of receiving the ciliary processes of the choroid, and the folds calculated to be lodged in the corresponding furrows of these processes. The annexed figure is a representation of the vitreous humour of the human eye thus treated. " If the cornea and iris be removed from a human eye within a few hours after death, a dark circle surrounding the lens, between it and the anterior extremities of the ciliary pro- cesses, may be observed : this is the part of the corona ciliaris of the vitreous humour to which the ciliary processes of the choroid do not extend, which appears dark on account of its perfect transparency ; the converging strict are evident, even on this part where the ciliary processes are not insinuated, interrupting the view if we attempt to look into the bottom of the eye by the side of the lens. It is, in my opinion, therefore certain, that part of the vitreous humour enters into the formation of the posterior chamber of the aqueous humour. The demonstration of this fact is, however, attended with difficulty, because the flaccidity arising from even slight evaporation of the fluids of the eye permits the ends of the ciliary processes which present themselves in the posterior chamber of the aqueous humour to fall towards the circumference of the lens, and appear attached there. For myself I can say that having made the dissection in the way just pointed out, the eye of course in water, and beneath one of those globular vessels which I formerly described, I could see to the bottom of the eye through the space in front of the vitreous humour, between the ciliary processes and the margin of the lens ; this space is, however, perhaps larger in some individuals than in others. Each fold of the corona ciliaris of the vitreous humour seems to consist of two layers of hyaloid membrane, capable of being separated one from the other byinrlation, and ad- mitting of communication with each other round, the lens. It appears to me that the canal of Petit or canal godronne is formed in consequence of these folds receiving the injected air one from the other ; it is, however, generally described as being formed by the membrane of the vitreous humour splitting at the circumference of the lens, one layer going before and the other behind that body, the canal existing between these two layers and the capsule of the lens. That the capsule of the lens has no share in the formation of the canal of Petit, I conclude from filling this canal with air, and allowing the part to remain for some days in water, and then with great care removing the lens included in its capsule; this I do not find, however, causes the air to escape from the cells, but leaves them presenting nearly the original appearance ; and after the air has escaped, I can pass a small probe all round in this canal, 194 EYE. raising by this means the folds from the hyaloid membrane. It is difficult, however, to pre- serve the air in these folds for any length of time under water, because the tendency of the air to ascend causes the rupture of the membrane, by which it is allowed to escape. After the lens, included in its proper capsule, has been detached from its situation on the vitreous humour, the space it occupied pre- sents the appearance of a circular depression, surrounded by those productions of the hyaloid membrane of which I have just spoken ; the vitreous humour remaining in every respect perfect, notwithstanding this abstraction of the lens." M. Ribes, in the Memoires de la Societe" Medicale d'Emulation for 1816, describes the ciliary processes of the vitreous humour as follows. " At the anterior part of the vitreous humour, and at a short distance from the cir- cumference of the crystalline, may be seen a ciliary body almost altogether similar to that of the choroid, and which has been named by anatomists corona ciliaris, but no writer has hitherto pointed out its structure, or the impor- tant office it appears to perform. Each of these processes has a margin adherent to the vitreous humour, and encroaches a little on the circumference of the lens. It appears to me impossible to ascertain whether the surfaces are reticulated, but they are villous. The free margin is obviously fringed, and presents nearly the variety of appearance observed in the fringes of ciliary processes (of the choroid) of different animals examined by me, except that the summits are black ; the interval which separates each process of the vitreous humour is a species of depressed transparent gutter. The black colour of the free margins and the transparency of the space which separates each ciliary process adorns the anterior part of the vitreous humour with a circle remarkable for its agreeable effect, and which has been com- pared to the disc of a radiated flower." Dr. Knox, in a communication made to the Royal Society of Edinburgh, at the same time that mine was made to the Medico-Chirurgical Society, describes the ciliary processes of the choroid as follows : " In whatever way, the membrane or assemblage of membranes pro- ceeds forwards to be inserted into the circum- ference of the capsule of the lens, forming in its passage numerous longitudinal folds, and small projecting fimbriated bodies, by which, in a natural state, the transparent humours are connected with the superjacent ciliary body (of the choroid) ; when examined with a good glass, these folds are remarkably distinct, and the whole bears the closest resemblance in its distribution to the true ciliary body and pro- cesses. I have, therefore, ventured to call them the internal or transparent ciliary body, or the ciliary body of the hyaloid membrane, in contradistinction to that of the choroid." It must not be forgotten that these ciliary pro- cesses of the hyaloid membrane were described by Monro in his Treatise on the Eye, and are strongly marked in a coarsely executed plate. He considered that the retina was continued to the lens, and describes its course under the ciliary processes of the choroid ; thus " on ex- amining the retina with still greater accuracy, it appears that it has exactly the same number of folds or doublings that the choroid coat has; for it enters double between the ciliary pro- cesses, nearly in the same way that the pia mater enters into the coats of the brain. The furrows and doublings of the retina, which, if we are to use the favourite term ciliary, may be called its ciliary processes, make an impres- sion on the anterior part of the vitreous hu- mour." The structure alluded to was also observed by Hovius nearly an hundred years before. From the preceding observations respecting the ciliary processes of the vitreous humour, it may justly be inferred that the ciliary pro- cesses of the choroid, and these ciliary pro- cesses of the vitreous humour, are of the same nature, differing only in those of the choroid receiving red blood, while those of the vitreous humour receive a transparent fluid by their bloodvessels. The adaptation of these two circles of folds to each other appears to be a most beautiful example of mechanical con- struction occurring in soft parts : it is a species of dovetailing of the one structure into the other, by which an intimate union is secured between one part of considerable strength and another of extreme delicacy. A connexion equally perfect is established between the ex- ternal surface of the choroid at its margin, and the corresponding margin of the sclerotic, by means of the ciliary ligament; in fact, with- out these two provisions of ciliary ligament and ciliary processes, and their application between the sclerotic, choroid, and vitreous humour, the chambers of the eye must be imperfectly constructed, and the optical me- chanism of the organ defective. It is the mechanical bond between these dissimilar parts which perfects the chamber of aqueous humour, and prevents that fluid from escaping, either between the sclerotic and choroid, or between the choroid and vitreous humour. Of the crystalline leiis. — It has been al- ready stated, that there is a double convex lens within the sphere of the eye, at a short distance behind the external lens or cornea. This is the crystalline lens or crystalline humour, which gives additional convergence to the rays of light transmitted through the pupil. It is placed in a depression, formed for its reception on the anterior, compressed, or truncated portion of the vitreous humour, where that body approaches the back of the iris, and constitutes part of the boundaries of the posterior chamber of the aqueous humour. In this depression it adheres firmly to the hya- loid membrane, and from the vessels of that structure derives its nutriment. This double convex lens does not present the same curvature on both surfaces, the anterior being less curved than the posterior, in the ratio of about 4 to 3- Attempts have been made to determine with accuracy the nature of these curvatures, first by Petit, and subsequently by Wintringham, Chossat, and others. The re- EYE. 195 suits of the numerous experiments of Petit lead to the conclusion, that the anterior curvature is that of a portion of a sphere from six to seven lines and a half in diameter, the posterior that of a sphere of from five to six lines and a quarter. From the same source it appears that the dia- meter is from four lines to four lines and a half, the axis or thickness about two lines, and the weight three or four grains. I am, however, inclined to agree with the observation of Porter- field, that, " as it is scarce possible to measure the crystalline and the other parts of the eye with that exactness that may be depended on, all nice calculations founded on such measures must be fallacious and uncertain, and, therefore, should, for the most part, be looked on rather as illustrations than strict demonstrations of the points in question." The method by which Petit arrived at these results must render them of doubtful value, the curvatures having been determined by the application of brass plates cut to the requisite form. The results of Chossat's experiments, conducted with great care, and with the assistance of the megascope, are thus stated by Mr. Lloyd in his Treatise on Optics : " This author has found that the cornea of the eye of the ox is an ellipsoid of revolution round the greater axis, this axis being inclined inwards about 10°. The ratio of the major axis to the distance between the foci in the generating ellipse he found to be 1.3 ; and this agreeing very nearly with 1.337, the index of refraction of the aqueous humour, it follows that parallel rays will be refracted to a focus, by the surface of this humour, with mathemathical accuracy. The same author found likewise that the two surfaces of the crystalline lens are ellip- soids of revolution round the lesser axis ; and it is somewhat remarkable that the axes of these sur- faces do notcoincide in direction either with each other, or with the axis of the cornea, these axes being both inclined outwards, and containing with each other, in the horizontal section in which they lie, an angle of about 5P." It must not be forgotten that these observations apply to the crystalline of the ox, not to that of man, and also that, as Chossat himself admits, the evaporation of the fluid part of the lens, or the absorption or imbibition of the water in which it is immersed, may materially alter the curva- ture. I cannot myself believe it possible to separate a fresh lens in its capsule perfectly from the hyaloid membrane without injuring its structure, and endangering an alteration in its form. Haller states that Kepler considered the anterior convexity to approach to a sphe- roid, and the posterior to a hyperbolic cone. Wintringham states the results of his inquiries as to this matter as follows : — " In order to take the dimensions of the eye of an ox, I placed it on a horizontal board and applied three moveable silks, which were kept extended by small plummets, so as to be exact tangents to the arch of the cornea, as well at each can- thus, as at the vertex ; then applying a very exactly divided scale, I found that the chord of the cornea was equal to 1 .05 of an inch, the versed sine of this chord to be 0.29, and con- sequently the radius of the cornea was equal to 0.620215 of an inch. I then carefully took off the cornea, and replaced the eye as before, and found, by applying one of the threads as a tan- gent to the vertex of the crystalline, that the distance between this and the vertex of the cor- nea was 0.355 of an inch. Afterwards I took the crystalline out without injuring its figure, or displacing the capsula, and then applying the threads to each surface of this humour, as was done before to the arch of the cornea, I found that the chord of the crystalline was 0.74 of an inch, and its versed sine, with respect to the anterior surface, to be 0.189 of an inch, and consequently the radius of this surface was 0.45665 of the same. In like manner the versed sine to the same chord, with respect to the posterior surface of the crystalline, I found to be equal to 0.38845 of an inch. Lastly, I found the axis of the crystalline and that of the whole eye from the cornea to the retina to be 0.574, 2.21 respectively.'" Whatever doubts may be entertained respecting the accuracy of the measurements of the lens, there can be none that the form is different at different periods of life, in the human subject. It also appears to differ in different individuals at the same period of life, and probably the curvature is not the same in both eyes. In other animals the dif- ference in form is most remarkable. In the human fetus, even up to the ninth month, it is almost spherical. Petit states that he found the anterior curvature in a fetus of seven months, a portion of a sphere of three lines diameter, and the posterior of two and a half, and the same in a new-born infant. In an in- fant eight days old, the anterior convexity was a portion of a sphere of four lines, and the posterior of three. All anatomists concur in considering the lens to approach more to a sphere at this period. In childhood the curva- tures still continue much greater than in ad- vanced life ; from ten to twenty probably de- crease, and from that period to forty, forty-five, or fifty, remain stationary, when they become much less; being, according to the tables of Petit, portions of spheres from seven to even twelve lines in diameter, and on the posterior of six or eight. Every day's observation proves that the lens becomes flattened, and its curva- tures diminished as persons advance in life. It is seen in dissection, when extracted by opera- tion, and even during life; the distance between its anterior surface and the back of the iris be- ing so great in some old persons, that the sha- dow of the pupil may be seen upon it, while at an earlier period it actually touches that part of the membrane. This diminution of the curva- tures of the lens commences about the age of forty-five. Petit found the anterior convexity varying from a sphere of about seven to twelve lines diameter, and the posterior from fire to eight in persons from fifty to sixty-five years of age. The alteration in power of adaptation, and the indistinctness of vision of near objects which takes place at this period, is probably to be attributed to this cause, although a diminu- tion of the muscular power of the iris, and con- sequent inactivity of the pupil, may contribute to the defect. It is also to be recollected that the density of the lens is much increased at this period, and that the young person whose lens o 2 196 EYE. presents greater curvatures does not require concave glasses, as the old person requires con- vex ones. The state of the eye, after the re- moval of the lens by operation for cataract, proves that it is a part of the organ essentially necessary for correct vision. When the eye is in other respects perfect, without any shred of opaque capsule, any irregularity or adhesion of the pupil, or any alteration in the curvature of the cornea, as in young persons who have had the lens properly broken up with a fine needle through the cornea, vision is so good for distant objects, that such persons are able to pursue their common occupations, and walk with safety through crowded streets, but they require the use of a convex lens, of from three and a half to five inches focus, for reading or vision of near ; old persons, however, generally require convex glasses on all occasions after the removal of the lens. That the curvatures of the lens are fre- quently different in different individuals may be inferred from the frequency of short sight, or defective power of adaptation, not attributa- ble to any peculiarity of the cornea. Petit states that he found lenses of which the two convexities were equal, and others of which the anterior was greater than the posterior, and more than once, one more convex on its ante- rior surface in one eye, while that in the other eye was in a natural state. He also occasion- ally found the lens as convex in the advanced period of life as in youth. I have repeatedly observed the perfection of vision and power of adaptation much greater in one eye than the other in the same individual, without any defect of the cornea, pupil, or retina ; and occasionally have found young persons requiring the com- mon convex glasses used by persons advanced in life, and old persons becoming near-sighted, and requiring concaves. The annexed letters shew the difference of curvature at the different periods of life, as represented by Sbmmerring. A is the lens of the foetus; B, that of a child of six years of age ; and C, that of an adult. Fig. 117. ABC The colour of the lens is also different at different periods of life. In the foetus it is often of a reddish colour; at birth and in in- fancy it appears slightly opaque or opaline ; in youth it is perfectly transparent; and in the more advanced periods of life acquires a yel- lowish or amber tint. These varieties in colour are not visible, unless the lens be removed from the eye, until the colour becomes so deep in old age as to diminish the transparency, when it appears opaque or milky, or resembling the semitransparent horn used for lanterns. The hard lenticular cataract of advanced life appears to be nothing more than the extreme of this change of colour, at least when extracted and placed on white paper it presents no other disorganization ; but the lens of old persons, when seen in a good light and with a dilated pupil, always appears more or less opaque, al- though vision remains perfect. The depth of colour is sometimes so great, without any milkiness or opacity, that the pupil appears quite transparent although vision is lost. This is perhaps the state of lens vaguely alluded to by authors under the name of black cataract. The consistence of the lens varies as much as its colour. In infancy it is soft and pulpy, in youth firmer, but still so soft that it may be crushed between the finger and thumb, and in old age becomes tough and firm. Hence it is that in the earlier periods of life cataracts may be broken up completely into a pulp, and absorbed with certainty, while in old persons they adhere to the needle, unless very deli- cately touched, and are very liable to be de- tached from the capsule and thrown upon the iris, causing the destruction of the organ. On this account, therefore, the operation of extrac- tion must generally be resorted to in old per- sons labouring under this form of cataract, while the complete division of it with the needle and exposure of the fragments to the contact of the aqueous humour secures its removal by absorption in young persons. It must not, however, be forgotten that the softer lenticular cataract occasionally occurs in ad- vanced life. The crystalline lens is a little heavier than water. Porterfield, from the experiments of Bryan Robinson, infers that the specific gra- vity of the human lens is to that of the other humours as eleven to ten, the latter being nearly the same as water; 'and W.intringham, from his experiments, concludes that the den- sity of the crystalline is to that of the vitreous humour in the ratio of nine to ten; the spe- cific gravity of the latter being ;to water as 10024 to 10000. The density of the lens is not the same throughout, the surface being nearly fluid, while the centre scarcely yields to the pressure of the finger and thumb, especially in advanced life. Wintringham found the spe- cific gravity of the centre of the lens of the ox to exceed that of the entire lens in the propor- tion of twenty-seven to twenty-six. The re- fractive power is consequently greater than that of the other humours. On this head Mr. Lloyd, in his Optics, says, " In their refrac- tive power, the aqueous and vitreous humours differ very little from that of water. The re- fractive index of the aqueous humour is 1.337, . and that of the vitreous humour 1.339; that of water being 1.336. The refractive power of the crystalline is greater, its mean refracting index being 1.384. The density of the crystal- line, however, is not uniform, but increases gradually from the outside to the centre. This increase of density serves to correct the aber- ration by increasing the convergence of the central rays more than that of the extreme parts of the pencil." Dr. Brewster, in his Treatise on Optics, says, " I have found the following to be the refractive powers of the different humours of the eye, the ray of light being incident upon them from the eye : aqueous humour 1.336; crystalline, surface 1.3767, centre 1.3990, mean 1.3839; vitreous humour 1.3394. But as the rays refracted by the aqueous humour pass into the crystalline, and EYE. L97 tliose from the crystalline into the vitreous humour, the indices of refraction of the sepa- rating surface of these humours will be, from the aqueous humour to the outer coat of the crystalline 1.0466, from the aqueous humour to the crystalline, using the mean index, 1.0353, from the vitreous to the outer coat of the cry- stalline 1.0445, from the vitreous to the crystal- line, using the mean index, 1.0332." Dr. Young says, " On the whole it is probable that the refractive power of the centre of the human crystalline, in its living state, is to that of water nearly as 18 to 7; that the water im- bibed after death reduces it to the ratio of 21 to 20 ; but that on account of the unequable den- sity, its effect in the eye is equivalent to a refraction of 14 to 13 for its whole size." Respecting the chemical composition of the lens, Berzelius observes, that " the liquid in its cells is more concentrated than any other in the body. It is completely diaphanous and colourless, holding in solution a particular animal matter belonging evidently to the class of albuminous substances, but differing from fibrine in not coagulating spontaneously, and from albumen, inasmuch as the concentrated solution, instead of becoming a coherent mass on the application of heat, becomes granulated exactly as the colouring matter of the blood when coagulated, from which it only differs in the absence of colour. All those chemical properties are the same as those of the co- louring matter of the blood. The following are the principles of which the lens is com- posed : peculiar coagulable albuminous matter 35.9, alcoholic extract with salts 2.4, watery extract with traces of salts 1.3, membrane form- ing the cells 2.4, water 58.0. From the preceding observations it might reasonably be supposed that the lens is com- posed of a homogeneous material, such as al- bumen or gelatine, more consolidated in the centre than at the circumference ; but this is not the case ; on the contrary, it exhibits as much of elaborate organization as any other structure in the animal economy. It consists of an outer case or capsule, so totally different from the solid body contained within it, that they must be separately investigated and de- scribed. The body of the lens, it has been already stated, consists of certain saline and animal ingredients combined with more than their weight of water, and when perfectly transparent presents the appearance of a tena- cious unorganized mass; but when rendered opaque by disease, loss of vitality, heat, or im- mersion in certain fluids, its intimate structure becomes visible. If the lens with the capsule attached to the hyaloid membrane be removed from the eye and placed in water, the following day it is found slightly opaque or opaline, and split into several portions by fissures extending from the centre to the circumference, as seen in fig. 118. This appearance is rendered still more obvious by immersion in spirit, or the addition of a few drops of acid to the water. If a lens thus circumstanced be al- lowed to remain some days in water, it con- tinues to expand and unfold itself, and if delicately touched and opened by the point of a needle, and carefully transferred to spirit, and as it hardens is still more unravelled by dissection, it ultimately presents a remarkable fibrous or tufted appearance, as represented in the figure below, drawn by me some years ago from a preparation of the lens of a fish thus treated (the Lophius piscatorius ). The three annexed figures represent the structure of the lens above alluded to: A is the human crystal- line in its natural state; B, the same split up into its component plates ; and C, unravelled in the fish. Fig. 118. C This very remarkable structure of the body of the lens appears to have been first accu- rately described by Leeuwenhoek, subse- quently by Dr. Young, and still more recently by Sir David Brewster. Leeuwenhoek says, " It may be compared to a small globe or sphere, made up of thin pieces of paper laid one on another, and supposing each paper to be composed of particles or lines placed some- what in the position of the meridian lines on a globe, extending from one pole to the other." Again he says, " With regard to the before- mentioned scales or coats, I found them so exceedingly thin, that, measuring them by my eye, I must say that there were more than two thousand of them lying one upon another." " And, lastly, I saw that eacjj^of these coats or scales was formed of filaments or threads placed in regular order, side by side, each coat being the thickness of one such filament." The peculiar arrangement of these fibres he describes as follows : " Hence we may collect how ex- cessively thin these filaments are; and we shall be struck with admiration in viewing the won- derful manner they take their course, not in a regular circle round the ball of the crystalline humour, as I first thought, but by three dif- ferent circuits proceeding from the point L, which point I will call their axis or centre. They do not on the other side of the sphere approach each other in a centre like this at L, but return in a short or sudden turn or bend, where they are the shortest, so that the filaments of which each coat is composed have not in reality any termination or end. To explain this more particularly, the shortest filaments, M K, H N, and O F, which fill the space on the other side of the sphere, constitute a kind of axis or centre, similar to this at L, so that the fila- ments M K, having gone their extent, and filled up the space on the other side, in like manner as is here shewn by the lines ELI, return back and become the shortest filaments H N. These filaments H N, passing on the other side 198 EYE. of the spheve, again form another axis or centre, and return in the direction O F, and the fila- ments O F, again on the other side of the sphere, collect round a third centre, and thence return in the direction K M ; so that the fila- ments which are on this side of the sphere collect round a third centre, and thence return in the direction KM; so that the filaments which are on this side the shortest, on the other side are the longest, and those which there are the shortest are here the longest." Annexed is Leeuwenhoek's representation (fig. 119). Fig. 119. Dr. Young differs from Leeuwenhoek as to the arrangement of the fibres and other parti- culars, and in his last paper corrects the de- scription given by himself in a former one ; he says, " The number of radiations (of the fibres) is of little consequence , but I find that in the human crystalline there are ten on each side, not three, as I once from a hasty observation concluded." " In quadrupeds the fibres at their angular meeting are certainly not conti- nued as Leeuwenhoek imagined." Beneath is Dr. Young's last view of the arrangement of the fibres, which Dr. Brewster has shown to be incorrect, but the introduction of which is jus- tified by the source from which it is derived. Fig. 120. Sir David Brewster says that the direction of the fibres is different in different animals; the simplest arrangement being that of birds, and the cod, haddock, and several other fishes. In it the fibres, like the meridians of a globe, con- verge to two opposite points of a spheroidal or lenticular solid, as in the annexed figure. Fig. 121. The second or next simplest structure he detected in the salmon, shark, trout, and other fishes ; as well as in the hare, rabbit, and por- poise among the mammalia; and in the alli- gator, gecko, and others among reptiles. Such lenses have two septa at each pole, as in the annexed figure. % Fig. 122. The third or more complex structure exists in mammalia in general, " in which three septa diverge from each pole of the lens, at angles of 120°, the septa of the posterior surface bisect- ing the angles formed by the septa of the ante- rior surface, as in the annexed figure (7?g.l23). EYE. 199 Fig. 123. The mode in which these fibres are laterally united to each other is equally curious. Sir David Brewster says that he ascertained this in looking at a bright light through a thin lamina of the lens of a cod, when he observed two faint and broad prismatic images, situated in a line exactly perpendicular to that which joined the common coloured images. Their angular distance from the central image was nearly five times greater than that of the first ordinary prismatic images, and no doubt whatsoever could be entertained that they were owing to a number of minute lines perpendicular to the direction of the fibres, and whose distance did not exceed the jj&dth of an inch. Upon ap- plying a good microscope to a well-prepared lamina, the two fibres were found united by a series of teeth exactly like those of rack work, the projecting teeth of one fibre entering into the hollows between the teeth of the adjacent one, as in fig. 124. Fig. 124. I have said that the lens consists of an outer case or capsule totally different from the solid body contained within it. This capsule is strong, elastic, and perfectly transparent. In the paper to which I have alluded in the Me- dico-Chirurgical Transactions, I gave the fol- lowing detailed description of its nature and properties : — " The real nature of the capsule of the lens has not, I think, been sufficiently attended to; its thickness, strength, and elasticity, have cer- tainly been noticed, but have not attracted that attention which a fact so interesting, both in a physiological and pathological point of view, deserves. That its structure is cartilaginous, I should conclude,^rs/, from its elasticity, which causes it to assume a peculiar appearance when the lens has been removed, not falling loose into folds as other membranes, but coiled in different directions ; or if the lens be removed by opening the capsule behind, and with- drawing it through the vitreous humour, allow- ing the water in which the part is immersed to replace the lens, the capsule preserves in a great degree its original form, especially in the eye of the fish ; secondly, from the density and firmness of its texture, which may be ascer- tained by attempting to wound it by a cataract needle, by cutting it upon a solid body, or compressing it between the teeth; thirdly, from its permanent transparency, which it does not lose except on the application of very strong acid or boiling water, and then only in a slight degree ; maceration in water for some months, or immersion in spirit of strength sufficient to preserve anatomical preparations, having little or no effect upon it. If the lens be removed from the eye of a fish dressed for the table, the capsule may be raised by the point of a pin, and be still found almost perfectly transparent. This combination of density and transparency gives the capsule a peculiar sparkling appear- ance in water, in consequence of the reflection of light from its surface, resembling a portion of thin glass which had assumed an irregular form while soft; this sparkling I consider very characteristic of this structure. The properties just enumerated appear to me to distinguish it from every other texture but cartilage ; still, however, it may be said that cartilage is not transparent, but even the cartilage of the joints is semi-transparent, and, if divided into very thin portions, is sufficiently pellucid to permit the perception of dark objects placed behind it, and we obtain it almost perfectly transparent where it gives form to the globe of the eye, as in the sclerotic of birds and fishes. If the soft consistence, almost approaching to fluidity, of the external part of the lens, be considered, the necessity of a capsule capable itself of pre- serving a determinate form is obvious. If the lens were enclosed in a capsule such as that which envelopes the vitreous humour, its sur- face could not be expected to present the ne- cessary regular and permanent curvature ; nor could we expect that if the form of the lens were changed, it could be restored without this provision of an elastic capsule." The capsule is liable to become opaque and constitute cataract, as the body of the lens is. These capsular cataracts are easily distinguished 200 EYE. from the lenticular. They never present the stellated appearance frequently observed when the texture of the opaque lens opens in the cap- sule as it does when macerated in water, nor the uniform horny or the milky blue appearance of common lenticular cataract. The opacity in capsular cataract exists in the shape of irregular dots or patches, of an opaque paper-white ap- pearance, and when touched with the needle are found hard and elastic, like indurated cartilage, the spaces between the specks of opacity fre- quently remaining perfectly transparent. It appears to be generally assumed by writers on anatomy that a watery fluid is interposed between the body of the lens and its capsule, from an incidental observation of Morgagni when discussing the difference in density be- tween the surface and centre of the lens; hence it has been called the aqua Morgagni. The observation of this celebrated anatomist, in his Adversaria Anatomica, which has led to the universal adoption of this notion, is, however, merely that upon opening the capsule he had frequently found a fluid to escape. " Deinde eadem tunica in vitulis etiam, bobusque sive recens, sive non ita recens occisis perforata, pluries animadverti, illico humorem quendam aqueum prodire : quod et in homine observare visus sum, atque adeo credidi, hujus humoris secretione prohibita, crystallinum siccum, et opacum fieri fere ut in extracto exsiccatoque crvstallino contingit." He does not, however, subsequently dwell upon or insist upon the point. I do not believe that any such fluid exists in a natural state, but that its accumula- tion is a consequence of loss of vitality; the water combined with the solid parts of the lens escaping to the surface and being detained by the capsule, as occurs in the pericardium and other parts of the body. In the eyes of sheep and oxen, when examined a few hours after death, not a trace of any such fluid can be detected, but after about twenty-four hours it is found in considerable quantity. In the human eye a fluid sometimes accumulates in the capsule, constituting a particular form of cataract, which presses against the iris, and almost touches the cornea ; but such eyes are, I believe, always unsound. From this erro- neous notion of an interposed fluid between the lens and its capsule has arisen the adop- tion of an unsustained and improbable conclu- sion, that the lens has no vital connexion with its capsule, and consequently must be produced and preserved by some process analogous to secretion. Respecting this matter I have ob- served, in the paper above alluded to, " The lens has been considered by some as having no connexion with its capsule, and consequently that its formation and growth is accomplished without the assistance of vessels; such a notion is so completely at variance with the known laws of the animal economy, that we are justi- fied in rejecting it, unless supported by un- questionable proof. The only reasons which have been advanced in support of this conclu- sion are, the failure of attempts to inject its vessels, and the ease with which it may be separated from its capsule when that mem- brane is opened. These reasons are far from being satisfactory; it does not necessarily follow that parts do not contain vessels, be- cause vve cannot inject them ; we frequently fail when theie can be no doubt of their exist- ence, especially where they do not carry red blood. I have not myself succeeded in in- jecting the vessels of the lens, but I have not repeated the trial so often as to make me despair of accomplishing it, more especially as Albinus, an anatomist whose accuracy is universally acknowledged, asserts, that after a successful injection of the capsule of the lens, he could see a vessel passing into the centre of the lens itself. Lobe, who was his pupil, bears testimony to this. The assertion that the lens is not connected with its capsule, I think I can show to be incorrect; it has been made from want of care in pursuing the inves- tigation, and from a notion that a fluid exists throughout between the lens and its capsule. When the capsule is opened, its elasticity causes it to separate from the lens ; especially if the eye be examined some days after death, or has been kept in water, as then the lens swells, and often even bursts the capsule and protrudes through the opening, by which the connexion is destroyed. I have however satis- fied myself that the lens is connected with its capsule (and that connexion by no means slight) by the following method. I remove the cornea and iris from an eye, within a few hours after death, and place it in water, then with a pair of sharp-pointed scissors I divide the capsule all round at the circumference of the lens, taking care that the division is made behind the anterior convexity, so that the lens cannot be retained by any portion of the cap- sule supporting it in front. I next invert the eye, holding it by the optic nerve, when I find that the lens cannot be displaced by agitation, if the eye be sufficiently fresh. In the eye of a young man about six hours dead, I found that, on pushing a cataract needle into the lens, after the anterior part of the capsule had been removed, I could raise the eye from the bottom of the vessel, and even half way out of the water, by the connexion between the lens and its capsule. It afterwards required consider- able force to separate them, by passing the needle beneath the lens, and raising it from its situation. I believe those who have been in the habit of performing the operation of ex- traction, have occasionally encountered consi- derable difficulty in detaching the lens from its situation after the capsule had been freely opened, this difficulty I consider fairly refer- able to the natural connexion just noticed." When the lens enclosed in its capsule is de- tached from the hyaloid membrane, the con- nexion between it and the capsule is destroyed by the handling, and, in consequence, it moves freely within that covering, affording to those who believe that there is no union between the two surfaces fallacious evidence in support of that opinion, which, if not sustained by better proof, should be abandoned. Dr. Young in- sists upon the existence of the natural con- nexion by vessels and even by nerves between EYE, the lens and its capsule ; he says, " The cap- sule adheres to the ciliary substance, and the lens to the capsule, principally in two or three points ; but I confess I have not been able to observe that these points are exactly opposite to the trunks of nerves; so that probably the adhesion is chiefly caused by those vessels which are sometimes seen passing to the cap- sule in injected eyes. We may, however, dis- cover ramifications from some of these points upon and within the substance of the lens, generally following a direction near to that of the fibres, and sometimes proceeding from a point opposite to one of the radiating lines of the same surface. But the principal vessels of the lens appear to be derived from the central artery, by two or three branches at some little distance from the posterior vortex, which I conceive to be the cause of the frequent adhe- sion of a portion of a cataract to the capsule about this point ; they follow nearly the course of the radiations and then of the fibres ; but there is often a superficial subdivision of one of the radii at the spot where one of them enters." The great size of the vessels distri- buted on the back of the capsule in the foetus strengthens the conclusion that the lens is fur- nished with vessels as the rest of the body. When the eye of a foetus of seven or eight months is finely injected, a branch from the central artery of the retina is filled and may be traced through the centre of the vitreous hu- mour to the back of the capsule, where it ramifies in a remarkably beautiful manner, assuming, according to Sommerring, a stellated or radiating arrangement. Zinn declares that he found branches from this vessel penetrating the lens : " Optime autem placet observatio arteriolar lentis, in oculo infantis, cujus vasa cera optime erant repleta, summa voluptate mihi visas, quam prope marginem ad convexi- tatem posteriorem diktam, duobus ramulis perforata capsula in ipsam substantiam lentis profunde se immergentem cortissime con- spexi." He also quotes the authority of Ruysch, Moeller, Albinus, and Winslow, as favouring the same view. Against such au- thority I find that of the French systematic writer Bichat advanced ; but on such a point his opinion is of little value. Annexed is Zinn's representa- Fig. 125. tion of the distribu- tion of the branch of the central artery on the back of the capsule, from a preparation in Lieberkiihn's mu- seum. Similar fi- gures have been given by Albinus, Sommerring, and Sir Charles Bell. Of the aqueous humour. — In the preliminary observations at the commencement of this article, I stated that a cavity or space filled with water exists between the cornea and crys- talline lens, in which space the iris is extended, with its aperture or pupil, to moderate the quantity of light, and interrupt the passage of the extreme rays. It is bounded anteriorly by the concave inner surface of the cornea, and posteriorly by the crystalline lens and other parts, and is necessarily divided into two spaces or chambers by the iris. That in front of the iris, called the anterior chamber, is bounded by the concave inner surface of the cornea anteriorly, and by the flat surface of the iris posteriorly, which, I have already stated, is a plane, not a convex surface, as represented in the plates of Zinn and others. The size of this space is necessarily small, and varies in different individuals according to the convexity of the cornea, which also frequently varies. It is always, however, sufficiently large to allow the surgeon to introduce a needle to break up a cataract without wounding the iris or cornea. The posterior chamber is bounded in front by the back of the iris, and behind by the crys- talline lens ; with that portion of the hyaloid membrane of the vitreous humour, which is between the anterior termination of the ciliary processes of the choroid and the circumference of the lens. The circumference of the pos- terior chamber is bounded by the anterior ex- tremities of the ciliary processes of the choroid, as they extend from the vitreous humour to the back of the iris. It does not appear to be generally admitted or well understood that any part of the hyaloid membrane of the vitreous humour enters into the composition of the posterior chamber of the aqueous hu- mour, notwithstanding the decisive opinion and accurate representation of the celebrated Sommerring, in which I entirely concur, as I have stated above in describing the vitreous humour. The size of the posterior chamber has been the subject of much discussion and contro- versy, and various attempts have been made by freezing the eye and other means to deter- mine the matter. Petit, after a careful inves- tigation, considered that the distance between the lens and iris was less than a quarter or half a line, in which Haller appears to concur. Winslow, in the Memoirs of the French Aca- demy for 1721, insists that the iris is in contact with the lens. Lieutaud, in his Essais Ana- tomiques, is equally positive on this point, and even denies altogether the existence of a posterior chamber. The question is not an indifferent one, inasmuch as it involves impor- tant considerations as to operations for cataract and inflammations of the iris. Modern ana- tomists appear, generally, to consider the dis- tance between the lens and iris to be greater than it really is. Although I cannot agree with Winslow and Lieutaud that the margin of the pupil is always in contact with the lens, I believe it frequently is so, especially in the earlier periods of life, when the curvatures of the lens are considerable. In iritis adhesions generally take place between the margin of the pupil and the capsule of the lens, a conse- quence not easily accounted for, if the parts be not iu contact. In old age the lens be- comes much flattened, and therefore retreats from the pupil, to such a degree that the sha- 202 EYE. dow of the iris may often be seen in aerescentic form on a cataract ; and in such persons, whe- ther from this cause or from the inflammation not being of the adhesive character, blindness is more frequently attended with dilated pupil. In breaking up cataracts through the cornea, I have repeatedly satisfied myself of the con- tact or close vicinity of the two surfaces by placing the needle between them. The an- nexed outline section, from the work of Sbm- merring, shews how small he considered the space between the iris and lens, and displays accurately how the posterior chamber is formed by the iris an- teriorly, the lens pos- teriorly, and the cili- ary processes at the circumference, with the small circular portion of the hyaloid mem- brane of the vitreous humour between the ciiliary processes of the choroid and the circumference of the lens. It appears to me unaccountable why sur- geons, with these anatomical facts before them, still continue to introduce the needle into the posterior chamber, to break up cataracts, in- stead of passing it through the cornea into the anterior chamber, where ample space exists, and a full view is obtained of all the steps of the operation. In doing so the needle is thrust through opaque parts among delicate structures, into a narrow cavity, where, hidden by the iris, it can be used with little certainty of correct application. At the same time, instead of penetrating the simple structure of the cornea, which bears injury as well as any other struc- ture of the body, the instrument pervades the fibrous sclerotic, a structure impatient of in- jury and prone to inflammation, punctures the ciliary ligament at the imminent risk of in- juring one of the ciliary nerves or even wound- ing the long ciliary artery, and finally passes through one of the most vascular parts in the body, the corpus ciliare. The practice appears a signal instance of the influence of education, habit, and authority in setting improvement at defiance. The proofs afforded of the close vicinity of the margin of the pupil to the cap- sule of the lens, should remind the surgeon that one of the greatest dangers to be ap- prehended in iritis is the adhesion of these two parts, and that one of the first steps in the treatment should be to separate them by the application of belladonna, which, by its pecu- liar influence on the pupil, dilates that aper- ture, and, consequently, brings its margin more opposite the circumference of the lens and at a greater distance from the prominent central portion. The aqueous humour, although constituting so essential a part of the optical mechanism of the eye, is but small in quantity ; according to Petit not more than four or five grains. Its specific gravity and refractive power scarcely differ from that of water; and according to Berzelius, 100 parts contain 98.10 of water, 1.15 of chloruret of soda with a slight trace of alcoholic extract, 0.75 of extractive matter soluble in water only, and a mere trace of albumen. It is perfectly transparent, but is said to be milky in the foetus. The source from which this fluid is derived has been the subject of controversy in con- sequence of Nuck, a professor of anatomy at Leyden, having asserted that he had discovered certain ducts through which it was transmitted, and published a small treatise to that effect, which ducts were proved to be vesssels by a cotemporary writer, Chrouet, in which deci- sion subsequent authors have concurred. In the present day this fluid is generally believed to be secreted by a membrane lining the cavity, as the fluid which lubricates the serous cavities is secreted by their lining membranes. Al- though this is in all probability the fact, the circumstances are not exactly the same in both cases. In the serous cavities, merely as much fluid as moistens the surface is poured out, while in the chamber of the aqueous humour sufficient to distend the cavity is secreted. In the serous cavities the membrane from which they derive their name can be demonstrated ; in the chamber of aqueous humour this can scarcely be accomplished. I have resorted to various methods to enable me to demonstrate the existence of the membrane of the aqueous humour on the back of the elastic cornea, such as maceration, immersion in hot water, soaking in alcohol, and treating with acids, alkalis, and various salts, but without effect. In describing the structure of the cornea, I have shewn that the elastic cornea itself can- not for a moment be considered the membrane in question, on account of its strength, thick- ness, elasticity, and abrupt termination ; and I do not think that the demonstration of a serous membrane expanded on such a struc- ture as transparent cartilage is to be expected, inasmuch as the demonstration of the synovial membrane on the cartilages of incrustation in the joints is attended with much difficulty. The pathological fact which tends most to prove the existence of such a membrane here, is, that in iritis, especially that of a syphilitic character, the aqueous humour appears often very muddy, especially in the inferior half of the chamber; this, however, in the latter stages may be found to arise from a delicate speckled opacity on the back of the cornea, which re- mains permanently, and injures vision con- siderably. Analogy also favours the inference that the whole cavity of the chamber must be lined by serous membrane, inasmuch as all structures, of whatsoever nature they may be, in the serous or synovial cavities, are so covered or lined. This provision is so universal, that if such various structure, as the elastic cornea, iris, capsule of the lens, ciliary processes, and hyaloid membrane, which enter into the con- struction of the chamber of aqueous humour, be exposed to the contact of the fluid without EYE. 203 any intervening membrane, it constitutes an unexpected anomaly in the animal ceconomy. The consequences of inflammation greatly strengthen the conclusion that the cavity is lined by a membrane of the serous character. The slightest injuries or even small ulcers of the cornea are frequently accompanied by effu- sion of purulent matter into the anterior chamber, from the extension of the inflam- mation into that cavity, constituting the hy- popion or onyx of the books ; and the yellow masses which appear on the iris in syphilitic iritis, whether they are abscesses, or as they are called, globules of lymph, are effusions beneath a delicate membrane, as vessels may be seen with a magnifying glass, ramifying over them. In iritis the rapidity with which adhesions are formed between the margin of the pupil and the capsule, proves that these two structures are covered by a membrane of this nature. In addition to all these facts the still more conclusive one is to be adduced, namely, that the membrane can without diffi- culty be demonstrated on the back of the iris, as I have stated in speaking of that part of the organ, and as it is represented in Jig. 127, where the fold of membrane stained with black pigment is seen turned down from that structure. In the preceding pages I have availed my- self of whatever valuable and appropriate facts in comparative anatomy I found calculated to illustrate or explain the structure of the human eye. There are, however, two organs in other animals which do not exist even in the most imperfect or rudimental state in the human subject — the pecten or marsupium nigrum in birds, and the choroid gland or choroid muscle in fishes. Of the pecten. — This organ is called pecten from its folded form bearing some resemblance to a comb, and marsupium nigrum from its resemblance in the eye of the ostrich to a black purse, according to the anatomists of the French Academy, who compiled the collection of memoirs on comparative anatomy. The organ is obviously a screen projected from the bottom of the eye forward toward the crys- talline lens, and, consequently, received into a corresponding notch or wedge-shaped hollow in the vitreous humour; it appears to be of the same vascular structure as the choroid, and is deeply stained with the black pigment, which renders it perfectly opaque and imper- vious to light. The annexed figure, from the work of D. W. Sommerring, represents it in the eye of the golden eagle. Fig. 128. Fig 127. It is composed of a delicate membrane, highly vascular, folded exactly like the plaits of a fan, and when removed with sharp scissors from the bottom of the eye, and its free margin cut along the edge so as to allow the folds to be pulled open, it may be spread out into a strip of continuous riband-shaped membrane, as seen in Jig. 1 29, from a paper of Sir E. Home's in the Philosophical Transactions for 1822. Fig. 129. The first account I find of it is by Petit in the Mem. de 1'Acad. Roy. 1735. He says it is a trapezium or trapezoid, five lines long at the base, and three lines and a half deep, com- posed of parallel fibres, and that a fine trans- parent filament runs from the anterior superior angle to the capsule of the crystalline lens, not easily seen on account of its transparency, and that sometimes the angle itself is attached to the capsule near its margin. Haller, in his work " Sur la formation du coeur dans le HP poulet," describes it as follows: — " It is a black membrane folded at very acute angles, as the paper of a fan, upon which transparent vessels are expanded ; it generally resembles the ciliary processes. It originates from the sclerotic in the posterior part of the eye by a serrated line, pierces the choroid, retina, and vitreous humour to attach itself to the side of the capsule of the crystalline, very near the corona ciliaris. The posterior extremity is broad, and the anterior narrows till it becomes 204 EYE. adherent to the capsule of the lens by an inser- tion a little narrower. This insertion appears to be effected by the intervention of the hyaloid membrane, to which this fan is attached. I have not had time to establish this con- nexion to my satisfaction, and I still entertain doubts respecting it. I have seen a red artery accompany this feather-like production and run to the crystalline. It would be very convenient for physiology that this folded membrane should prove muscular ; we should then have the organ sought after, which would retract the crystalline to the bottom of the eye." In the Elementa Physiologic, t. v. p. 390, he says it originates from the entrance of the optic nerve, but that you may remove the retina and leave the pecten. He says again, " it advances for- ward to the posteiior part of the capsule, to which it sometimes adheres by a thread, and sometimes the lens is merely drawn toward it." An artery and vein is supplied to each fold, and perhaps to the capsule of the lens. In the Opera Minora he says that there are two red vessels to each fold in the kite, and no cord runs to the lens ; that in the heron a branch of artery runs to each fold, and it adheres so closely to the lens that it cannot be ascertained whether a red vessel runs from it to the lens or not ; that in the duck it is contracted toward the lens, and adheres to it by a thread contain- ing a red vessel. He also says that in the wild duck it arises from the margin of the linea alba, which terminates the entrance of the optic nerve, contains numerous vessels, and adheres to the lens ; and in the pie it is large and adheres to the lens, so as to pull it. D. W. Sbmmerring says, that in the pecten of the golden eagle, of which Jig. 128 is a representation, there are fourteen folds like ciliary processes, and that it adheres by a transparent filament to the capsule of the lens ; that in the great horned owl it is short and thick, with eight folds, and adhering to the lens by an hyaloid filament, although at a great distance from it; and that in the macaw it is longer than broad, has seven folds, and adheres to the lens. In the ostrich he says it is shaped like a patella at its base, which is white, oval, and thick; eight lines long and five broad, distinctly separate from the choroid, above which it rises, the retina being interposed. From the longer diameter of this patella (or base) a white plane or lamina projects even up to the lens, and sends out on each side seven small plaits, the lower ones partly double, the upper ones simple, black, and delicate. This conical body, something like a black purse, tapers toward the lens, and by its apex is attached to the capsule by a short semi-pellucid ligament. The white substance of the base and partition of the pecten should not be con- founded with the medullary part of the optic nerve, which, emerging on all sides from be- neath the base, expands into a great, ample, and tender retina, terminating behind the ciliary processes with a defined margin. Cuvier, in his Lectures on Comparative Anatomy, says, " It appears of the same nature as the choroid, although it has no connexion with it ; it is like- wise very delicate, very vascular, and imbued with black pigment. Its vessels are derived from a particular branch of the ophthalmic artery, different from two which belong to the choroid ; they descend on the folds of the black membrane and form ramifications there of great beauty when injected. This mem- brane penetrates directly into the vitreous humour, as if a wedge had been driven into it ; it is in a vertical plane directed obliquely forward. The angle nearest the cornea in those species in which it is very broad, and all its anterior margin in those in which it is narrow, comes nearly to the inferior boundary of the capsule of the crystalline. In some species it approaches so near that it is difficult to say whether or not it is attached to it ; such is the case in the swan, the heron, the turkey, &c. according to Petit ; but there are other birds in which it remains at some distance, and in which it does not appear to attach itself except to some of the numerous plates which divide the vitreous humour into cells. In the swan, heron, and turkey, this membrane is broader in the direction parallel to the produced extre- mity of the optic nerve than in the contrary direction. In the ostrich, cassowary, and owl the reverse is observed. It is folded like a sleeve in a direction perpendicular to the caudal termination of the optic nerve. The folds are rounded in most species ; in the ostrich and cassowary they are compressed and sharp, and so high perpendicular to the plane of the membrane that at first sight it resembles a black purse. The folds vary in number, there being sixteen in the swan, ten or twelve in the duck and vulture, fifteen in the ostrich, and seven in the grand duke or great horned owl. The purpose for which the pecten exists in the eyes of birds does not appear to be fully ascertained. Petit says, " when a bird views an object with both eyes, the rays enter oblique- ly in consequence of the situation of the cornea and crystalline lens, and proceed to the bottom of the eye ; but as they enter in lines parallel to the membrane, they do not encounter it. The rays which enter the eye in lines perpen- dicular to the plane of the cornea encounter this membrane, and are absorbed by it as well as those which come from the posterior side ; the subject is, however, a difficult one." Haller supposed that it was merely destined to afford a medium through which vessels might pass to carry blood to the crystalline. Cuvier says, " It is difficult to assign the real use of this membrane. Its position should cause part of the rays which come from objects at the side of the bird to fall upon it. Petit believed that it was destined to absorb these rays and prevent their disturbing distinct vision of objects placed in front. Others thought, and the opinion has been lately reiterated by Home, that it possesses muscular power, and that its use is to approach the lens to the retina when the bird wishes to see distant objects. Never- theless, muscular fibre cannot be detected in it, and the experiments intended to prove its muscularity after death are not absolutely con- clusive ; moreover, as it is attached to the side EYE. 205 of the crystalline, it could move it only obliquely." The experiments and inferences contained in Sir E. Home's paper in the Phi- losophical Transactions for 1796, do not appear to me worthy of any attention. A pecten in an imperfect or rudimentary state appears to exist in fishes and reptiles, and has been noticed by Haller, W. Sommerring, and Dr. Knox. In the article Aves of this work Mr. Owen has also described the pecten, and to that arti- cle I refer the reader for additional information. Of the choroid gland or choroid muscle. — The eyes of fishes present several remarkable peculiarities, to be accounted for perhaps from their occasional residence in the obscurity of the deep, and at other times near the surface, exposed to the full blaze of sunshine; they must also be frequently exposed to great pres- sure at considerable depths. The sclerotic is not merely a fibrous membrane, but is strength- ened by a cartilaginous cup, and sometimes even by one composed of bone ; the cornea is generally flat or presenting little of lenticular character; the crystalline lens is spherical, and so dense that its central part is a hard solid ; and the choroid presents the remarkable pecu- liarity which I have now to describe. On cutting through the cartilaginous sclerotic, a fluid is found generally interposed between this and the choroid; at least it is so in the genus gadus, (cod, haddock, &c.) The external part of the choroid is formed by a most beau- tiful membrane of a brilliant silver aspect, scarcely to be distinguished from that metal when rough and recently cleaned. On tearing this membrane away, the vascular choroid is exposed, and a red horse-shoe-shaped promi- nent mass, encircling the entrance of the optic nerve, appears. This is the choroid gland or choroid muscle. The veins of the choroid, apparently commencing from the iris, ascend in tortuous inosculating branches, of enormous size compared with the dimensions of the part, and appear to terminate by entering this horse- shoe-shaped organ, but this is not their distri- bution, as it is not hollow. The area enclosed by the organ round the optic nerve does not exhibit the same extreme vascularity. On pulling away a delicate film which covers the organ, it appears composed of lamina: or plates divisible into fibres, which run transversely from within outwards, confined into a compact body by the delicate film just spoken of, and a concave depression in the structure beneath. The annexed plate, made from an accurate drawing of a careful dissection, represents the general form and vascularity remarkably well. Fig. 130. Haller, speaking of the choroid in fishes, says, " this organ is a fleshy pulp, composed of short columns densely consolidated, resembling red gelatine." Cuvier says, " its colour is com- monly a vivid red, its substance is soft and more glandular than muscular ; at least fibres cannot be distinguished on it, although the bloodvessels form more deeply coloured pa- rallel lines on its surface. Its form is com- monly that of a small cylinder bent like a ring round the nerve, which ring is not, however, complete ; a segment of greater or less length is always deficient. Sometimes, as in the Perca lubrax, it is composed of two pieces, one on each side of the optic nerve. In other cases it is not in a circle but an irregular curve, as in the Salmon, Tetradon mola, and Cod ; but in the carps and most other fishes it approaches to to a circle. Those who suppose that the eye changes its figure according to the distance of objects, think that this muscle is destined to produce this effect by contracting the choroid ; but it appears to me that the numerous vessels passing out of it should rather lead to its being considered a gland destined to secrete some of the humours of the eye. These vessels are white, fine, very tortuous, and appear to traverse the tunica Ruyschiana; they are well seen in the Te- tradon mola and Perca labrax. In the Cod they are very large, anastomose together, and are covered by a white and opaque mucus. This gland does not exist in the cartilaginous fishes, as the Rays and Sharks, in which it approaches more to the character of the eye in the Mam- malia, as has already been observed in speak- ing of the tapetum and ciliary processes." D. W. Summering says, " Around the insertion of the nerve is seen a peculiar red, thick, soft body of a horse-shoe shape, respecting which it is doubted whether it be muscular, glandular, or merely vascular. It is undoubtedly ex- tremely vascular, and contains many large, branching, inosculating vessels, forming a proper membrane gradually becoming thin, and terminating at the iris. This vascular membrane constitutes the second or middle layer of the choroid." This description applies to the eye of the Cod. Sir E. Home, in a Croonian lecture published in the Philoso- phical Transactions for 1796, says that Mr. Hunter considered the organ in question to be muscular, and proceeds to state that " this muscle has a tendinous centre round the optic nerve, at which part it is attached to the scle- rotic coat; the muscular fibres are short, and go off from the central tendon in all directions: the shape of the muscle is nearly that of a horse-shoe; anteriorly it is attached to the choroid coat, and by means of that to the sclerotic. Its action tends evidently to bring the retina forwards ; and in general the optic nerve in fishes makes a bend where it enters the eye, to admit of this motion without the nerve being stretched. In those fishes that have the sclerotic coat completely covered with bone, the whole adjustment to great dis- tances must be produced by the action of the choroid muscle; but in the others, which are by far the greater number, this effect will be 206 EYE. much assisted by the action of the straight muscles pulling the eye-ball against the socket, and compressing the posterior part, which, as it is the only membranous part in many fishes, would appear to be formed so for that pur- pose" Although it must be admitted that these conclusions of Sir E. Home are derived from insufficient data, and are probably incor- rect in many particulars, yet it is not very im- probable that the part in question may be mus- cular, and, if so, may be instrumental in adapt- ing the eye to distance by pushing up the retina toward the lens. The organization of the part is certainly not merely vascular, as stated by Cuvier, and undoubtedly bears a stronger resemblance to muscular than any other structure ; it also retains the peculiar colour of red muscle after all the rest of the eye has been blanched by continued macera- tion in water. I think, however, Sir E. Home goes too far when he describes a central tendon without reservation. For further information on the subject of this article, see Vision, and Vision, Organ of. BIBLIOGRAPHY. — In pursuit of information re- specting the anatomy of the eye, the student need scarcely go farther back than Zinn's work, or the article on the same subject in Haller's Elementa Physiologic The older anatomical writers were, generally speaking, uninformed on the subject. Ruysch's works contain some observations worthy of attention at the time he wrote, but now scarcely worth recording ; especially as he was a vain man, and wrote for present fame and character rather than truth. In Albinus's Annotationes Academical a few facts are recorded, upon the accuracy of which the student may place reliance, as he was an anatomist. Morgagni also added to the existing information of the period at which he wrote, but has left little more than notes or cursory remarks. Petit's papers in the Memoires de 1 Academie Royale des Sciences contain much original and valuable matter. In this earlier period the con- tributions of Nuck, Hovius, Briggs, and Leeuwen- hoek should not be overlooked. Coteraporary with or immediately following Haller and Zinn, Porter- field, Le Cat, Lieutaud, the second Monro, Blu- menbach, Sommerring, and many others made valuable additions to our information on this subject. The annexed list contains the titles of those works which I have consulted ; some of the more modern German monographs I have been obliged to quote or consult from those who copied from them, having endeavoured in vain to procure them : such are those of Ddllenger, Chelius, Huschke, Jacob- son, Kicser, Weber, and some others. Nuck, Lialographia et ductuum aquosorum ana- tome nova, Lugd. Bat. 1695. Warner Chrouet, De tribus humoribus oculi, 1691. Hovius, De circu- lari humorum motu in oculis, Ludg. Bat. 1716. Briggs, Ophthalmographia, Lugd. Bat. 1686. Leuwenhoek, Arcana naturae detecta, Delphis, 1695 ; or in the Philosophical Transactions, or in the translation of his select works by Hoole, Lond. 1816. Ruyschii Thesaurus, Amstel. 1729. Al- binus, Annotationes academical. Morgagni, Ad- versaria anatomica, Ludg. Bat. 1723, and Epistola:, Venetiis, 1750. Haller, Elementa physiologia; corporis humani, torn. v. Lausanne, 1763 ; also in Opera minora, and Formation du cocur dans le poulet. Zinn, Descriptio anatomica oculi humani, Gotting. 1780, and also in Commentarii Societatis Rpgiie Scientiarum Gotlingenses, t. iv. 1754. Petit, in Memnires de l'Academie Royale des Sciences, 1723, 25, 26, &c. Winslow, Mem. de i'Acad. 1721. Moeller, Observationes circa retinam, in Halleri Disputationes anatomica; select, t. vii. Camper, De quibusdam oculi paitibus, in Halleri Disp. anat. Lobe, De oculo humano, in same. Wintringham, On animal structure, London, 1740. Le Cat, Traite des Sens, Rouen, 1740. Bertrandi, Dissertatio de oculo, in Opere anatomische e cerusiche. Porterfield, On the eye, Edinburgh, 1759. Lieutaud, Essais anatomiques, Paris, 1766. Dud- dell, Treatise on the diseases of the horny coat in the eye, Lond. 1729. Descemet, An sola lens crystallina cataractae sedes, Paris, 1758. Demours, Lettre a M. Petit, Paris, 1767. Brendel, De fabrica oculi in fcctibus abortivis, Got. 1752. Blumenbach, De oculis leucoethiopum et iridis motu, Gott. 1786. Wachendorf, Commercium litterarium, 1744. Fon- tana, Traite sur le venin de la vipere, Florence, 1781. Walther, J. G. Epistola anat. ad Wilhelm Hunter, Berolin, 1758. Soemmering, Abbildungen des menschlichen Auges, or Icones oculi humani ; or translated into French by Demours. Simmering, also in Commentarii Soc. Reg. Gotting. Monro, On the brain, the eye, and the ear, Edin. 1797. Camparetti, Observationes dioptrics; et anatomica; de coloribus, visu et oculo, Patavii, 1798. Sattig, Lentis crys- tallina; structura fibrosa, Halae, 1794. Mauchart, De cornea, in Haller's Disputationes chirurgica;, or in Reuss Dissertationes Tubingenses. Dr. Young, in the Philosophical Tansactions, 1793 et seq. Home, in several papers in the Philosophical Transactions, see Index. Red, De structura ner- vorum, Halae, 1796. Rosenthal, De oculi quibus- dam partibus, 1801. Angely, De oculo organisque lachrymalibus, Erlang. 1803 ; or, again, Schreger vergleichenden Anatomie des Auges, Leipzig, 1810. Baerens, Systematis lentis crystallina monographia, Tubings, 1819, and in Radius Scriptores oph- thalmologic minores. Clemens, Tunica; cornea; et humoris aquei monographia, Gott. 1816, and in Radius, S. O. M. Sacks, Historia duorum leu- ccethiopum, Solisbaci, 1812. Maunoir, Sur l'or- ganisation de l'iris, Paris, 1812. Ribes, in Me- moires de la Societe Med. d'Emulation, an 8ieme, Paris, 1817. Chelius, Ueber die durchsichtige Hornhaut des auges, Carlsruhe, 1818. Voit, Oculi humani anatomia et pathologia, Norimbergae, 1810. Hegar, De oculi partibus quibusdam, Gott. 1818. Cuvier, Le<;ons d'anat. comp. Bell's Anatomy. Meckel's Handbuch d. menschl. anatomie, or the French translation. Sommering, D. W. De oculorum hominis animaliumque sectione horizontale, Gott. 1818. Knox, Comparative anatomy of the eye. Trans. Royal Society of Edinburgh, 1823. Cloquet, J. Sur la membrane pupillaire, Paris, 1818. «/acofao»,SuppIementa ad ophthalmiatriam.Havnia;, 1821. Ddllenger, Illustratio ichnographica oculi, Werceburg, 1817. Weber, De motu iridis, Lipsia;, 1828. Jacob, in Philosophical Transactions, 1819. Martegiani, Novae observationes de oculo human., Napoli, 1812. Sawrey, An account of a newly- discovered membrane in the human eye, Lond. 1807. Husche, Commentatio de pectinis in oculo avium potestate, Jense, 1827. Schneider, Das ende der nervenhaut in menslichen auges, Munchen, 1827. Kieser, De anamorphosi oculi, Gott. 1804. Jacob, in Medico-Chirurgical Transactions, vol. xii. Lond. 1823. F. A. ab Ammon, De genesi et usu maculae lutrae, Vinariae, 1830. Dieterich, F. C. Uber die verwundengen des linsensystems, Tubing. 1824. Ddllenger, Uber das Strahlenblaitchen im menschlkhen auges in Acta Ph. Med. Acad. Caesar- Leop. Car. nat. cur. t. ix. Horrebow, M. Tractatus de oculo humano, Havniae, 1792. Jacob Imans, Dissertatio inaug. de oculo, Lugd. Bat. 1820. Lieblien, V. Bemerkungen uber das system der krystalliense bei Saugthieren und. vogeln. Wurz- burg, 1821. Muller, F. Anatomische und physio- logische darstellung des menschlichen auges, Wien. 1819. J. Muller, Zur vergliechenden physiologie des gesichtssines des menschen und der Thiere, Leipsig, 1826. G. R. Treviranus, Beilrage zur anatomie und physiologic der Sinnesweikezcuge des FACE. 207 Menschen und der Thiere, 1 Heft. Bremen, 1828. Wardrop's Morbid anatomy of the eye. Dalrymple's Anatomy of the eye, Lond. 1834. Mackenzie, On diseases of the eye, Lond. 1834. Lloyd, On light and vision, Lond. 1831. Biot, Precis elementaire d« physique, Paris, 1824. Langenbeck, B. C. R. De retina, Gott. 1836. Berzelius, Traitede chimie, Paris, 1833. Ammon, Zeitschrift fur die oph- thalmologic. Radius, Scriptores ophthalmologic! minores. Reils, Archiv. fiir die physiologie. Meckel's Archiv. F. Arnold, Untersuchungen iiber das auge des menschen, Heidelberg, 1832. Giralde, Sur ['organization de l'ceil, Paris, 1836. For the latest observations on the retina, see Ehrenberg, Beobachtung iiber Structur des Seelenorgans, Ber- lin, 1836. For the comparative anatomy of the eye, which is still imperfect, I refer the student to the paper of Zinn in the Gottingen Commentaries, as above quoted ; Bidloo, De oculis et visu ; the article on the eye in Haller's Elementa Physiologiae ; Cam- paretti's observations; Home's papers in the Philo- sophical Transactions ; Knox's Comparative ana- tomy of the eye ; Cuvier's Comparative anatomy ; J. Muller, Vergleichende Physiologie des Gesicht- sinnes ; and, above all, to D. W. Sbmmering's book. For perfect systematic treatises on the anatomy of the eye, the student is referred to Zinn's well-known and highly valuable work, Arnold's work just quoted, and, in English, Mr. Dalrymple's treatise. (Arthur Jacob.) FACE (in anatomy) (Gr. nzaawrtov ; Lat. fades, vultus, os ; Tr.fuce; Germ. Antlitz, Gesicht ; Ital. faccia ). — In vertebrated animals this term is applied to denote the anterior part of the head, with which most of the organs of the senses are connected ; while the cranium is destined to contain and protect the encephalic organs, the face is the seat of the organs of sight, smell, and taste, and in some animals of a special organ of touch. The relative sizes of cranium and face depend, therefore, in a great measure on the relative development of those important organs which belong to each. For the characters of the face in the different classes of animals, we refer to the articles devoted to the anatomy of them, and to the article Osseous System. Face (in human anatomy). The face is situated before and below the cranium, which bounds it above ; on the sides, it is limited by the zygomatic arches, behind by the ears and the depression which corresponds to the upper region of the pharynx, and below by the base of the lower jaw and the chin. The disposition pf the face is symmetrical ; its anterior surface is trapezoidal, the largest side being above ; and its vertical section is triangular. It pre- sents an assemblage of organs which serve dif- ferent purposes, and which by their configura- tion and proportions constitute what are called the features; individually the face presents many varieties, not only in the foim and degree of development of its several parts, as the nose, mouth, &c, but also in the condition of its bones, muscles, skin, and adipose tissue. The varieties of form presented by the face afford some of the most distinctive characters of the different races of mankind. It differs also ac- cording to the age and sex of the individual ; in the infant, the peculiarities depend princi- pally upon the disposition of the bones, and in particular on the absence of the teeth ; but the soft parts have also their distinctions at this age, for while the fat is abundant, the muscles are but little developed, and hence the slightly marked features and the plump cheeks of infancy. In old age, again, the aspect of the face is the reverse of this, for not only do its thinness and the predominance of the muscles throw out the features, but the skin is covered with folds and wrinkles, from its own relaxation and the absence of fat, aided perhaps by the action of the muscles. The loss of the teeth, moreover, allows the lower jaw (when the mouth is closed) to be thrown in front of the upper, and thus the length of the face is dimi- nished, and a peculiar expression is imparted to the countenance. In women, (from the delicacy of the features and the abundance of the cellular tissue,) the face preserves the roundness of form, and something of the characteristics of childhood. Bones of the Face. — The bones of the face comprise all those of the skull which do not contribute to form the cavity for the brain ; they inclose, either by themselves or in con- junction with the adjacent bones of the cranium, 1 . the organs of three senses, viz. sight, smelling, and taste ; 2. the organs of mastica- tion and the orifices of the respiratory and digestive canals ; 3. they give attachment to most of the muscles of expression. The face is divided into the upper or the fixed, and the lower or the moveable jaw, both of which are provided with teeth. The lower jaw is a single and symmetrical bone ; the upper jaw, though formed of thirteen bones, consists principally of two, viz. the ossa maxillaria superiora, to which the others may be considered as additions, being attached to them immoveably, and forming altogether one large, irregular, and symmetrical piece, which constitutes the upper jaw. Of the fourteen bones which contribute to the face, two only are single or median ; the others are double, and form six pairs, viz. 2 ossa maxilla superioris ; 2 ossa paluti ; 2 ossa nasi ; 2 ossa mala ; 2 ossa lachrymalia ; 2 ossa turbinata inferiora. The two single bones are, the vomer and the os maxilla in- serioris. The superior maxillary bones, ( ossa maxil- luria superiora ; Germ, die Obern Kinnbacken- beine oder Oberkiefer.) These bones, situated in the middle and front of the face, are of a very irregular figure ; they are united below along the median line, and form together, the greater part of the upper jaw. Each has four surfaces, viz. i. a facial or anterior; 2. a posterior or zygomatic ; 3. an internal or naso- palatine; 4. a superior or orbitur. The borders are three; 1. an anterior or naso-maxillary ; 2. a posterior or pterygoid; 3. an inferior or alveolar. The facial surface presents from before backwards, 1. the fossa myrtiformis, a depres- sion situated above the incisor teeth, which gives attachment to the depressor labii superi- oris; 2. the canine ridge, which corresponds to the socket of the canine tooth, and which sepa- rates the myrtifoim from, 3. the canine (or the 208 FACE. infra-orbitar) fossa, which gives attachment to the levator anguli oris, and at the upper part of which is seen the infra-orbitar foramen, giving exit to the vessels and nerves of the same name ; 4. the malar ridge, a semicircular crest which descends vertically from the malar pro- cess to the alveolar border of the bone, and divides its facial from its zygomatic surface, which is prominent behind, where it forms the maxillary tuberosity, most conspicuous before the exit of the last molar tooth, which in the child is lodged within it. On this surface are several small holes, (posterior dental fora- mina,) which are the orifices of canals for the posterior and superior dental vessels and nerves. From the upper and front part of the ante- rior surface of the bone a long vertical process {the nasal process ) ascends between the nasal and lachrymal bones to be united with the frontal ; its external surface is rough, presenting small irregular holes, which transmit vessels to the cancellous interior of the bone and to the nose, and giving attachment to the levator labii superiorisalsque nasi muscle. The internal sur- face of this process is marked with some minute grooves and holes for vessels, and, tracing it from below upwards, by a transverse ridge or crest {the inferior turbinated ridge ) for the lower spongy bone ; above this by a depres- sion corresponding to the middle meatus; next by a crest ( the superior turbinated ridge ) for the upper spongy bone of the ethmoid ; and above this by a surface which receives and completes some of the anterior ethmoid cells. The nasal process has three borders: i. an anterior, thin and inclined from above downwards and forwards; above, it is cut obliquely from the internal towards the external surface of the bone, and below in the contrary direction, so that this edge of the nasal process and the corresponding border of the nasal bone with which it is united, mutu- ally overlap each other. 2. A posterior border, or surface, thick and divided into two margins by a deep vertical groove (the lachrymo-nasal canal) which contributes to lodge the lachrymal sac above, and the nasal duct below. The direction of the lachrymo-nasal canal is curved from above downwards and outwards ; so that its convexity looks forwards and inwards, and its concavity in the contrary direction. The inner margin of this groove is thin, and is united above to the anterior border of the os unguis, and below to the inferior spongy bone. The outer margin is bounded and gives attach- ment to the tendon and to some of the fibres of the orbicularis palpebrarum ; it commonly ter- minates below in a little tubercle (the lachrymal tubercle). 3. The upper border of the nasal process, which is short, thick, and irregular, is articulated with the internal angular process of the frontal bone. The orbitar surface of the bone is the small- est; it is quadrilateral, smooth, and slightly concave, with an inclination from above down- wards and from within outwards ; it forms the greater part of the floor of the orbit. Along the middle of its posterior half runs, in a direc- tion forwards and outwards, the infra-orbitar groove, which anteriorly becomes a complete canal {the infra-orbitar canal ), and finally divides into an internal or larger canal, which terminates at the infra-orbitar hole in the canine fossa, and into an external or small conduit, which runs in the anterior wall of the antrum, and conveys the superior anterior den- tal nerves to the incisor and canine teeth ; this outer subdivision of the canal presents several varieties in different individuals. The orbitar surface (or plate) has four borders: 1. The posterior, which, free and notched in the mid- dle by the commencement of the infra-orbitar canal, forms with the orbitar plate of the sphe- noid and palate bones the inferior orbitar or the spheno-maxillary fissure. 2. The internal, which articulates from behind forwards succes- sively with the palate, the ethmoid, and the lachrymal bones. 3. The anterior, short and smooth, separates the orbitar from the facial surfaces of the bone; at its inner extremity is the nasal process already described. 4. The external is united to the malar bone; on the outer side of this border is a rough triangular projecting surface (the malar process ) which receives the os mala, and which forms an angle of union between the anterior, posterior, and superior surfaces of the upper maxillary bone. The internal or naso-palatine surface is di- vided along the anterior three-fourths into two unequal parts by an horizontal plate of bone {the palatine process) : above this is the nasal portion forming the upper three-fourths of this surface, and below it, is the palatine part which forms the remaining fourth. The palatine process forms the anterior three- fourths of the floor of the nose, and roof of the mouth; it presents a smooth upper surface, concave transversely, and nearly flat in the op- posite direction : it is broad behind and narrow in front, where there is placed the orifice of the anterior palatine canal, which takes a direction downwards, forwards, and inwards, unites with the corresponding canal in the opposite bone at the median plane, and forms a common canal {the canulis incisivus ), which opens below by a hole {the foramen incisivum ) on the roof of the mouth, immediately behind the middle incisor teeth. The anterior palatine canals and the incisive canal, which are often included to- gether under a common name, form a tube re- sembling the letter Y, being bifid above and single below. The inferior surface of the pa- latine process is rough and concave, and forms the anterior and larger part of the roof of the mouth ; its internal border is long and rough, thick in front, narrow behind, and united with the corresponding border of the opposite bone forms the maxillary suture : this border is sur- mounted by a half-furrow which, with that of its fellow bone, forms a groove for the reception of a part of the vomer. The posterior border is short and cut obliquely at the expense of the upper surface ; it supports the anterior margin of the horizontal part of the palate-bone. The pala- tine division of the internal surface of the upper maxillary bone is narrow, and forms part of the arched roof of the mouth ; along its junc- tion with the palatine process is a broad shal- FACE. 20? low groove for lodging the posterior palatine nerves and vessels. The nasal portion of the internal surface is placed above the palatine process, and is lined on its anterior three-fourths by the pituitary membrane. Tracing this sur- face from before backwards we observe, 1. the lower aperture of the naso-lachrymal canal, situate just behind the inferior turbinated crest of the nasal process ; 2. posterior to this, the orifice of the maxillary sinus, or antrum of Highmore, which in the sepaiated bone is a large opening, but is contracted in the united face by the lachrymal, the ethmoid, the palate, and the inferior turbinated bones, which are attached around its margin. Above this aper- ture are seen some cells which unite with those of the ethmoid, and its lower edge presents a fissure in which is received the maxillary pro- cess of the palate-bone. Below the inferior turbinated crest, the naso-lachrymal canal and the orifice of the antrum, the bone is concave and smooth, and forms a part of the inferior meatus of the nose; behind this smooth surface and the orifice of the antrum, the bone is rough for the attachment of the vertical plate of the os palati, and it presents a groove, which, descending obliquely forwards to the palatine division of this surface, forms a part of the posterior palatine canal. The rnaxil/ary sinus (sinus maxillaris, antrum Hig/irnori ; Germ, die Oberkieferhohlc) oc- cupies in the adult the whole body of the bone : its form is triangular, with the base directed internally towards the orifice which has been already described, and the apex out- wards towards the malar process. Its superior wall is formed by the orbitar plate; the pos- terior corresponds to the maxillary tuberosity ; and the anterior to the canine fossa. All these walls present ridges or crests, which lodge canals for the passage of nerves. The posterior and anterior walls contain the su- perior, anterior, and posterior dental canals, which lodge nerves of the same name. The upper wall contains the infra-orbitar groove and canal, which gives passage to the upper maxillary nerve. Borders. — 1 . The anterior or naso-maxillary border is united above along the nasal process to the nasal bone. Below this it is thin and presents a deep semicircular notch, which forms the lateral and inferior portions of the anterior aperture of the nose. At the lower extremity of this notch the bone projects, and forms with its fellow of the opposite side the anterior nasal spine. The remainder of this border proceeds downwards and a little forwards to terminate on the alveolar border of the bone between the two middle incisor teeth. 2. The posterior or pterygo-pa/atine border, thick, rounded, and vertical, is united below to the palate bone, and above it forms, with the palate bone, the anterior border of the pterygo-maxillary fissure. 3. The inferior or alveolar border is thick and broad, especially behind, and forms about the fourth of an oval. It is perforated with conical cavities (alveoli ) for the reception of the roots of eight teeth. These cavities are VOL. It. separated by thin transverse laminae. Tracing them backwards from the anterior extremity of the border, the orifices of the two first are nearly circular, and receive the incisors ; they are the largest, and are placed below the nasal notch. The third, in form transversely oval, receives the canine tooth, is of great depth, and ascends in front of the canine fossa. The fourth and fifth, also transversely oval, but not so deep, receive the lesser molar teeth ; they generally present ridges in their septa which correspond to grooves in the fangs of the teeth which are implanted into them. The orifices of the three last cavities are quadrilateral, and receive the molar teeth. The sixth and seventh are subdivided into three lesser cavities, of which the two external are smaller than the inner one. Sometimes one of the molar teeth has four fangs, and then we find its socket subdivided into a cor- responding number of cavities. The eighth alveolus, which receives the last molar tooth or dens sapiential, is not so distinctly divided into subordinate cavities, but presents ridges like the lesser molar. The outline of the alveolar border is waving, convex where it corresponds to the alveoli, and depressed op- posite their septa. The whole of this border is covered by the gums, and presents innu- merable pores for the nutritious vessels. The surfaces of the alveoli are also similarly marked. Connexions. — The upper maxillary articu- lates with two bones of the cranium, viz. the ethmoid and frontal, and sometimes with the sphenoid by its pterygoid processes, or by an union of the orbitar plates of both bones at the outer extremity of the spheno-maxillary fissure. In this case the malar bone does not enter into the formation of this fissure. The upper maxillary articulates with its fellow and with all the bones of the face. The me- dian and lateral cartilages of the nose are at- tached to it. It receives the upper teeth, and gives attachment to eight muscles, viz. the orbicularis palpebrarum, the inferior oblique of the eye, the levator labii superioris alaeque nasi, the levator labii proprius, the depressor alae nasi, the compressor narium, the levator anguli oris, and the buccinator ; often also to some of the fibres of the temporal and the external pterygoid muscles. It lodges the naso-palatine ganglion, and gives passage to the infra-orbitar and to the anterior and pos- terior palatine and dental vessels and nerves. It forms the greater part of the sides of the nose, and of the floor of that cavity, and of the orbit, as well as of the roof of the mouth. It contains the maxillary sinus and the nasal duct. Structure. — This bone is lighter than might be expected from its size, being occupied by the large antrum maxillare. It is cancellous only at the tuberosity, along the alveolar border, and at the malar and palatine processes. Developement. — The ossification of this bone commences as early as the thirtieth or thirty- fifth day of fipetal life, near its alveolar border, and it is complete at birth. It presents at p 210 FACE. this period, and often much later, two remark- able fissures. 1. The incisive fissure, which may be traced from the alveolar border be- tween the canine and lateral incisor tooth backwards and upwards, along the incisive canal towards the nasal process : it is sel- dom observable on the facial surface of the bone. The part of the bone circumscribed by this fissure appears to correspond to the inter- maxillary bone of animals, and is probably developed as a separate piece : it supports the incisor teeth. 2. A fissure is often found ex- tending from the infra-orbitar groove forwards to the orifice of the canal. The existence of these fissures has led some anatomists to sup- pose that the bone is developed by these ossitic points. At birth and in infancy the bone presents a much greater proportion from before back- wards than vertically : its nasal process is long, its orbitar plate large, the antrum is already distinct, the tuberosity prominent, and there are some remarkable holes behind the incisor teeth, which are said to have an important connexion with the development of the second set of teeth. In the adult the increase in the vertical di- mensions corresponds with the developement of the antrum and alveolar border. In old age the alveoli are obliterated, the border con- tracts, and the jaw diminishes in height. In the small vertical diameter the senile and in- fantile upper jaw bear a resemblance to each other. In the inferior mammalia, the maxillary bones are separated anteriorly in the middle line by a bone called os intermaxillare or incisivum, which contains the superior incisor teeth when they are present ; sometimes this bone is distinctly divisible into two by suture. This bone is present, although the superior incisors be absent, as in Ruminants and Eden- tata, but in such cases is very small: on the other hand, when the incisor teeth are largely developed, it is of considerable size, as in the Rodentia. In the mature human foetus no sign of this bone exists, but in examining the skulls of foetuses about the third or fourth month of pregnancy, we observe it perfectly distinct from the maxillary bone. It sometimes happens that at more advanced periods, whether of in- tra or extra-uterine life, evidence of the separa- tion of the intermaxillary bone exists, and as Meckel says, we often find a transverse narrow " lacuna" on the vault of the palate, extending from the external incisor tooth to the anterior palatine foramen. According to Weber, how- ever, who examined the extensive collection of foetal skeletons belonging to Professor Ilg in Prague, the intermaxillary bone was distinct only in those that had a double hare-lip. He considers, however, that the intermaxillary bone readily separates when the skull of a child of one or two years old is placed for some time in dilute muriatic acid.* The palate bones, ( ossa palatinu ; Germ. * See Weber in Kroriep's Notizen, 1820, quoted in Hildebrandt's Anatomie, B. ii. S. 95. die Saumenbeine,) situated at the back part of the nose and roof of the mouth, locked be- tween the maxillary bones and pterygoid pro- cesses of the sphenoid, consist of two thin plates, one short and horizontal, the palatine ; the other long and vertical, the nasal. The palatine process, or plate, has two surfaces and four borders. The upper surface, or the nasal, is smooth and concave, and forms the posterior fourth of the floor of the nose. The lower sur- face, the palatine, rough, and slightly concave anteriorly, has on its posterior and outer part a transverse crest with a depression behind it for theattachmentof thecircumflexus palati muscle. In front and to the outer side of this is the inferior orifice of the posterior palatine canal, behind which are two or three small openings called accessoi'y palatine holes, and in front of it is the commencement of the groove which lodges the posterior palatine vessels and nerves. The anterior border is cut obliquely from below upwards and forwards, and rests on the posterior border of the palatine plate of the upper maxillary bone, forming with it the transverse palato-maxillary suture. The pos- terior border, thin and concave, gives attach- ment to the soft palate. The internal border, rough and thick, is united to its fellow of the opposite side ; above, it forms a grooved crest, which receives a part of the vomer, and is continuous with a similar crest formed on the internal border of the palatine plate of the upper maxillary bone. Behind, this border terminates in a sharp point, which, in conjunction with the corres- ponding projection of the opposite bone, forms the postei-ior nasal spine, to which the levator uvulae muscle is attached. The external border is continuous with the vertical plate. The nasal process, or plate, has two surfaces and four borders. The internal or nasal pre- sents, tracing it from below upwards, 1. a smooth concave surface, which forms part of the inferior meatus : 2. a horizontal crest, the inferior turbinated crest, for the attach- ment of the inferior turbinated bone : 3. ano- ther concave surface forming part of the mid- dle meatus : 4. another horizontal crest (the superior turbinated crest ), shorter than the former, for the attachment of the middle tur- binated bone of the ethmoid. This surface is covered with the pituitary membrane. The external or zygomato-maxillury surface is rough in front, where it rests against the upper maxillary bone ; behind this the lower two-thirds are marked by a groove, which, in conjunction with one on the upper maxillary bone, forms the posterior palatine canal. Above this, the bone is smooth, and forms the inner and deep part of the pterygo-maxillary fissure. The anterior border, thin and projecting, forms a process (the maxillary ) which is re- ceived into the fissure in the lower edge of the orifice of the maxillary sinus. The posterior or pterygoid border is united to the anterior border of the pterygoid process of the sphenoid : below, it becomes broad and is continued along a process which stands FACE. 211 downwards, outwards, and backwards, from the angle of union of the posterior borders of the vertical and horizontal plates of the bone. This process is the pterygoid or pyramidal, and presents three grooves behind, viz. one internal and one external, (of which the inner is the deeper,) for the reception of the anterior borders of the lower extremity of the pterygoid plates ; and a middle triangular groove extending high up, and which forms a part of the pterygoid fossa. The outer surface of this process is rough, and is articulated with the upper maxillary bone : its apex is continuous with the external pterygoid plate. The inferior border is united to the horizon- tal plate. The superior border presents a deep semi- circular notch (sometimes a hole), which with the sphenoid bone above forms the spheno- palatineforamen. This notch divides the upper border into two processes, 1. the posterior (the sphenoidal); 2. the anterior (the orbitar). The sphenoidal process is curved inwards and back- wards, and has three surfaces, 1. an internal or nasal, forming part of the cavity of the nose; 2. an external, which forms below the spheno- palatine foramen the deep wall of the pterygo- maxillary fissure ; 3. an upper, which is con- cave and rests against the body of the sphenoid bone, and contributes to the pterygo-palatine canal. The orbitar process stands upwards and outwards on a narrow neck, and presents five surfaces. 1. The anterior (or maxillary) arti- culates with the upper maxillary bone. 2. The internal (or ethmoidal) forms a cell which unites with those of the ethmoid. 3. A posterior (or sphenoidal) presents a cell uniting with the sphenoid, and communicating with its sinuses. 4. The superior (or orbitar), which is smooth and contributes to form the floor of the orbit: its posterior border forms a part of the spheno- maxillary fissure, and separates the orbitar sur- face from, 5. the external or zygomatic, which looks into the pterygo-maxillary fissure. Connexions. — Each palate bone articulates with five bones, viz. two of the cranium, the sphenoid and the ethmoid ; and with three of the face, the upper maxillary, the inferior turbi- nated, and the vomer, besides its fellow bone of the opposite side. It is lined with the buccal and pituitary membrane. It contributes to form the cavities of the mouth, nose, and orbit ; the pterygo-maxillary fissure, and the zygomatic and pterygoid fossae. It gives attachment to the soft palate, and passage to the spheno-palatine, pterygo-palatine, and posterior palatine vessels and nerves ; also to the two pterygoid muscles, the circumflexus palati, the levator uvulae, the palato-glossus, and the palato-pharyngeus. The structure is compact, except at its pte- rygoid process, where it is cancellous. Developement. — It is complete at birth, ex- cept that the vertical plate is short to corre- spond with the short vertical diameter of the upper maxillary. About the third month ossification appears in a single point, at the junction of the two plates with the pyramidal process. Malar bones (ossa mala- v. malaria v. zygo- matica ; Fr. os de la pommette ; Germ, die Jochbeine oder Backenbeine). — These bones, corresponding in situation to the prominence of the cheeks, are somewhat of a quadrilateral figure. Each presents three surfaces; 1. an external ox facial; 2. an internal or temporo- zygomatic ; 3. a superior or orbitar. There are besides four borders and four angles. The facial surface forms the eminence of the cheek, looks outwards and forwards, is smooth and slightly convex in front, and is marked by one or more small holes (malar foramina), which give passage to vessels and nerves. It is covered above by the integuments and the orbi- cularis palpebrarum, and below and externally it gives attachment to the zygomatic muscles. The temporo-zygomatic surface is smooth and concave below ; and internally there is a rough surface which rests on the malar process of the upper maxillary : about the centre or to- wards the upper part of this surface is observed the internal orifice of a malar canal or a malar hole. The temporal muscle is attached to this surface. The orbitar surface is smooth, concave, and is formed upon a plate of bone ( the orbitar process ), which stands inwards, and contributes to the outer wall and floor of the orbit : its op- posite surface above makes part of the tempo- ral fossa. On the orbitar surface we observe the orifice of a malar canal. The orbitar pro- cess has an irregular summit, which receives the frontal bone ; below, it is articulated with the outer border of the orbitar plate of the sphenoid ; in the middle it corresponds to the extremity of the spheno-maxillary fissure ; and inferiorly it is united to the outer border of the orbitar plate of the upper maxillary bone. Of the four borders two are anterior and two posterior. The anterior superior, or the orbi- tar, is smooth, concave, and forms the outer and lower third of the base of the orbit. The anterior inferior, or the maxillary, rests upon the malar process of the upper maxilla from its extremity to the inferior orbitar foramen. The posterior superior, or temporal border, is waved like the letter S, and gives attachment to the temporal fascia. The posterior inferior, or masseteric border, is thick, and gives attach- ment to a muscle of the same name. The four angles are, 1 . thick, rough, superior or frontal, which receives the external angular process of the frontal bone; 2. the interior or orbitar, which is pointed ; and, 3. the inferior or malar, which is round, and forms the extremities of the maxillary border, and which rests on the malar process of that bone. The posterior or zygomatic is cut obliquely from above down- wards and backwards, and supports the zygo- matic process of the temporal bone. Connexions. — The malar is connected with and locked between four bones, viz. the frontal, the sphenoid, the upper maxillary, and the temporal. It contributes to form the orbit, the temporal, and the zygomatic fossae. It gives attachment to four muscles, viz. the temporal, the masseter, and the two zygomatic ; and it gives passage to malar vessels and nerves. 212 FACE. The structure is compact, except near its upper and lower angles, where there is some cancellous tissue. Developement . — Its ossification commences in one piece about the fiftieth day, and is com- pleted at birth, when the bone appears thicker, and its orbitar plate larger in proportion than in the adult : its vertical diameter is, however, narrow, and the malar holes are large. The nasal bones (ossa nasi; Germ, die Nusenbeine ) form the upper part of the nose, and are placed between the nasal pro- cesses of the upper maxillary and below the frontal bones, inclining from above downwards and forwards. They have two surfaces, and their form is quadrilateral, the vertical exceed- ing the transverse diameter. They are stout and narrow above, and thin and broader below. The anterior or cutaneous surface is smooth, covered by the integuments and pyramidalis muscle, concave from above downwards, con- vex transversely. An oblique hole for the passage of vessels is usually found above the centre of one or both nasal bones, and some smaller foramina are scattered over the surface. The posterior or pituitary surface is concave, narrow, especially above, and lined by the olfactory membrane, presenting grooves for vessels and the internal orifice of the canal (or hole) mentioned above. The borders are four : a superior, short, thick, dentated, inclined from above down- wards and backwards, and resting on the nasal notch of the frontal bone between its two in- ternal angular processes : the inferior border, longer than the preceding, thin, jagged, in- clining from the median line downwards and outwards, and generally presenting about its centre a slight notch for the passage for a fila- ment of the nasal nerve. This border forms the upper and front part of the anterior opening of the nasal fossa, and gives attachment to the lateral cartilages of the nose. The external border is the longest, and is cut obliquely for its articulation with the nasal process of the upper maxillary bone. The internal border is shorter, thick and rough above, and thin be- low : it forms, on the inner aspect of the bone, in conjunction with the corresponding part of the bone of the opposite side, a ridge and groove for the reception of the nasal process or spine of the frontal bone, and for the upper and anterior border of the perpendicular plate of the ethmoid. Connexions. — The nasal bones articulate with each other, with the frontal, ethmoid, and upper maxillary bones, and with the lateral cartilages of the nose : they form a part of the cavity of the nose. Their structure is cancellous and thick above, thin and compact below. Developement. — They are perfectly ossified at birth, when they are proportionally longer than in the adult, corresponding in this respect with the depth of the orbit and the smallness of the anterior aperture of the nose. The ossifica- tion of each nasal bone commences by a single point about the beginning of the third month. The lachrymal bones ( ossa unguis v. lachry- malia ; Germ, die Thrdnenbeine ) are qua- drilateral in form, thin, semitransparent, and are situated on the anterior part of the inner wall of the orbit between the ethmoid, frontal, and upper maxillary bones ; they derive one of their names from the resemblance which they bear to a finger-nail. Each bone presents two surfaces and four borders. The external or orbitar surface is divided at its anterior third by a vertical crest, terminating below in a little curved process which forms the outer wall of the upper orifice of the nasal canal ; in front of this crest the bone is per- forated with numerous little holes, and its sur- face is concave and forms with that of the nasal process of the upper maxilla the canal for the lachrymal sac. The posterior part of this surface is smooth, nearly flat, and is continuous with that of the os planum of the ethmoid, which lies immediately behind it. The internal or ethmoidal surface is rough, and is divided by a vertical groove, which corresponds to the crest on the orbitar aspect of the bone ; the anterior division is convex and forms part of the middle meatus; the pos- terior division, is in contact with the ethmoid and contributes to close its cells. Of the four borders, the superior is the shortest and thickest ; it is irregular and arti- culates with the inner border of the orbitar plate of the os frontis. The inferior is divided into two parts by the lower extremity of the crest already described on the anterior surface of the bone ; in front of this the border de- scends along a thin process or angle of the bone, which is articulated with the inferior turbinated bone, and contributes to form the inner wall of the canal for the nasal duct ; behind, this border is broad, and rests on the inner margin of the orbitar plate of the upper maxillary bone. The anterior border is slightly grooved for the reception of the inner margin of the posterior border of the nasal process belonging to the upper maxilla. The posterior border is thin and articulates with the anterior edge of the os planum. The os unguis has four angles, of which the anterior inferior is remarkable for its length. Connexions. — This bone articulates with the frontal, the upper maxillary, the ethmoid, and the inferior turbinated ; it contributes to form part of the orbit of the cavity of the nose and of the groove for the lachrymo-nasal duct. It gives attachment to the reflected portion of the tendon of the orbicularis palpebrarum, and to the tendon of the tensor tarsi muscles. In structure it is thin and compact. Development. — It is complete at birth, ex- cept at its posterior superior angle, where there is a deficiency between it and the frontal and ethmoid bones, and where a separate piece is sometimes formed. It is broader from back to front in proportion, at this period of life, than in the adult, and its lachrymal groove is larger. Its ossification commences by a single point between the third and sixth months. A small lachrymal bone has been described as sometimes found at the lower part of the os unguis; and not unfrequently some separate FACE, 213 pieces are found at its angles, formed either from the ethmoid or from the orbitar plate of the upper maxillary bone. The inferior turbinated bones, (ossa spongiosa v. turbinata infima; Germ, die untern Muschel- beine ) of an oval form, thin and spongy in their appearance, are placed horizontally along the lower part of the outer wall of the nasal cavities, separating the middle from the inferior meatus, and contributing to increase the surface of the nose. Each bone presents two surfaces, two borders, and two extremities. The internal surface is rough, convex, and looks towards the septum of the nose, which it sometimes touches on one side when that partition inclines more than usually to the right or left. The external surface is concave, exhibiting many small fossae or pits ; it looks towards the upper maxilla and forms a part of the inferior meatus. Both surfaces are very irregular or spongy and are pitted by vessels, but especially by veins, which ramify abundantly upon them. The inferior border is convex and thick, particu- larly at its centre, where it descends towards the floor of the nose. The vpper border is thin and irregular, and presents from before backwards, 1. a thin edge, which is attached to the inferior turbinated crest on the nasal process of the upper maxilla; 2. a process (the lachrymal ) which ascends towards the curved process of the os unguis, with which and with the adjacent part of the upper jaw-bone it unites to complete the canal for the nasal duct; 3. some irregular projections ( ethmoidal pro- cesses) which ascend and unite with the ethmoid ; 4. a thin, curled, dog's-ear-looking process (the auricular or maxillary ), which, descending and overhanging the internal sur- face of the bone, is attached to the lower part of the opening of the antrum, which it con- tributes to circumscribe ; 5. an edge which is articulated with the inferior turbinated crest of the palate-bone. The orifice of the antrum is situated just above the centre of this border, and opens consequently into the middle mea- tus. The extremities or angles are formed by the union of the two borders ; the posterior extre- mity is more pointed than the anterior. Connexions. — Each inferior turbinated is united with four other bones, viz. the uppe* maxillary, the lachrymal, the ethmoid, and Jip palate. It is covered with the pituitary me"ui- brane ; it contributes to enlarge the surface of the nasal cavity, and to form a part of nasal canal and middle and lower meatus. Its structure is compact. Its development commences at the fifth montti by a single point of ossification. The vomer (Germ, das Pflugscharbein) is of a quadrilateral figure, and resembles a ploughshare; it is a single and symmetrical bone, situated in the median plane, and forming the posterior and inferior part of the septum nasi. It has two lateral surfaces and four borders. The surfaces, which are right' and left, are smooth, flat, and lined by the pitui- tary membrane; sometimes, when the bone inclines much to either side of the nose, one of these surfaces is convex and the other concave ; they present an oblique groove or grooves for the naso-palatine nerves and vessels. The superior border (or surface) is broad, and may be termed the base of the bone ; it presents a deep groove in the middle, which receives the rostrum of the sphenoid, and on each side of this are two plates or lamina? (sometimes called the alee) which are received into fissures of the sphenoid on each side of the rostrum, and which contribute to form a longitudinal canal for the ethmoidal vessels. The anterior border is oblique from above downwards and forwards; above it presents a deep groove, which is a continuation of that on the upper border, and which receives the perpendicular plate of the ethmoid : below, this border is nearly flat, where it is united to the middle cartilage of the nose. The inferior border is the longest, and is received into the grooved crest formed by the united palatine plates of the superior maxillary and palate bones ; in front this border extends as far as the anterior nasal spine. The posterior border, thick above, thin be- low, is oblique, slightly curved, and forms the partition between the two posterior openings of the nose. Connexions.- — The vomer is connected with four bones, viz. the sphenoid and ethmoid above, the superior maxillary and palate below : it is covered with the pituitary membrane, and forms, with the perpendicular plate of the ethmoid and the middle cartilage, the septum of the nose. Its structure is compact, and it is formed of two thin lateral plates, which are distinct above, but united inferiorly. Its development occurs by a single ossific point about the third month, and at birth it is completely ossified. The os maxillare informs (Germ, das untere Kiunbackenbein, oder der Unterkiefor). This single bone, which alone forms the lower jaw, occupies the lower and lateral parts of the face ; it is a flat, symmetrical bone, and bears some resemblance in shape to a horse-shoe. It con- sists of a middleor horizontal portion (the body ), and of two lateral ascending branches (the rami), which are connected with the body nearly at right angles. The body is curved, nearly horizontal, in- clining from before backwards, and a little upwards, and presents two surfaces and two ^orders. The anterior surface is convex, and has in the centre a vertical line (crista mentulis ex- terna), which marks the union of the two hai - as >.f which the bone consists in the young subject : this line terminates below in a tri- angular t.ninence (the mental process). The v$;, a .-u direction of the lower jaw at the sym- pl i , and its curved figure anteriorly, form- ii ; h it is termed the chin, are both charac- terise of the human race. From the angles J in' mental process arises on each side the -external oblique line, faintly marked in front, but becoming distinct as it ascends diagonally 214 FACE. along this surface of the bone to terminate at the anterior border of the ramus of the jaw; it gives attachment to muscles and separates the external surface of the bone into two parts, viz. an anterior superior, which presents, ex- ternal to the symphysis, 1. a depression (the J'ossa mentalis ) for the attachment of a muscle; 2. to the outer side of this the mental foramen, which is directed obliquely upwards and out- wards; it is the lower orifice of the inferior dental canal, which conveys nerves and vessels to the teeth of the lower jaw; 3. a number of ridges and grooves near the alveolar border of the jaw, which correspond to the sockets of the teeth and to the septa which divide them : this part of the bone is covered by the gums. The surface below and behind the oblique line is smooth, or only faintly marked with irre- gular lines for the attachment of the platysma myoides. The intei-nal surface of the body of the lower jaw is concave, and presents in the median line, at the symphysis, a vertical crest (crista merit alis interna ), which is not so distinct as the corresponding ridge on the outer surface of the bone : at its lower extremity is a tubercle having four summits ( the genial processes, yiniov, chin, spina interna,) which give attachment to two pairs of muscles, viz. the two superior genial processes to the genio- hyo-glossi, the two inferior to the genio- hyoidei : below and to the outer side of these processes, on the lower border of the bone, are two oval rough depressions, one on each side of the symphysis, for the attachment of the anterior bellies of the digastric muscles. From the genial processes proceeds obliquely upwards and backwards, to join the anterior border of the ramus of the jaw, the internal oblique line, or the mylo-hyoid ridge. It is distinctly marked and very prominent oppo- site the last molar tooth ; like the external oblique line it divides the bone diagonally into two triangular portions, the anterior of which, situated above and in front of the ridge, is smooth, concave, and to the outer side of the genial processes presents a depression ( sublingual J'ossa ) for the reception of the sub- lingual gland : elsewhere this surface is lined by the gums, and forms the inner wall of the alveolar cavities; but it is destitute of the ridges and depressions which are seen on the outer surface ot the bone. The triangular surface below the oblique line is marked by numerous small holes for the passage of nu- tritious vessels, and by a large depression (the submaxillary J'ossa ) for the reception of the submaxillary gland. The two oblique maxillary lines which have been just described divide the body of the jaw into two portions, one superior or alveolar, the other inferior or basilar: in the foetus the former predominates considerably; in the adult they are nearly equal, and in the edentulous jaw of old age the body almost entirely consists of the basilar portion. The upper or alveolar border forms a lesser curve than that of the alveolar border of the superior maxilla : like it, however, it presents sockets for the reception of sixteen teeth, which vary also in form and depth in correspondence with the fangs of the teeth which they lodge. The orifices of the sockets, however, take a direction different from those of the upper jaw, for while the sockets of the upper incisors look downwards and forwards, those of the lower are directed upwards and backwards; and again the alveoli of the upper canine and molar teeth look downwards and outwards, whereas those of the lower are directed up- wards and inwards : hence, from this different inclination of the teeth in the two jaws, and from the larger curve described by the alveolar border of the superior maxilla, we find that when the mouth is closed the upper front teeth cover the lower and at the sides overhang them a little. This arrangement is favourable to the division and mastication of the food. The lower border or base is smooth and thick, and forms a larger curve than the upper, so that the surfaces of this jaw have an in- clination from above downwards and forwards: it forms the oval border of the lower part of the face, and is the strongest portion of the bone. The rami are flat, quadrilateral processes, which stand up from the body of the jaw at almost a right angle : in the child and old person this angle is much more obtuse. Each ramus presents two surfaces and four borders. The external or masseteric surface has an inclination from above downwards and more or less outwards : it is rough, especially below, where it presents some irregular oblique ridges and depressions for the attachment of the masseter: in front of these marks, near the lower border of the bone, there is often a slight groove, which indicates the course of the facial vessels. The internal or pterygoid surface is also rough below for the attachment of the internal pterygoid muscle. In its centre is the spreading superior orifice (superior dental foramen) of the lower dentul canal, marked and partly hidden internally by a spine, which gives attachment to the internal lateral ligament of the temporo-maxillary articulation : from this hole, taking a direction downwards and for- wards is a groove (the mylo-hyoid groove ), which lodges the branch of the inferior dental artery and nerve. The borders of the rami are, an anterior or buccal, grooved below, where it corre- sponds with the alveolar border of the bone ; the margins of this groove, which are con- tinuous with the oblique lines of the bone, unite above and form a sharp convex edge. The posterior or parotid border is round and thick above, and narrow below, and is em- braced by the parotid gland : inferiorly and internally it gives attachment to the stylo- maxillaiy ligament. The superior or zygomatic border is sharp and concave, forming a notch ( the sigmoid notch ), which looks upwards. The inferior border is rounded, and is con- tinuous with the lower border of the body. The angles of the lower jaw are formed by the union of the body and rami ; each FACE. 215 is turned a little outwards, and in the adult forms nearly a right angle ; in the infant and in the old person it is obtuse. This part of the bone is prominent and separates the in- sertion of the masseter and internal pterygoid muscles. On the upper part of each ramus stand two processes, which are separated by the sigmoid notch ; the anterior is the coronoid, which is of a triangular form, flattened laterally, and sharp in front and behind ; its summit is somewhat rounded : this process gives at- tachment to the temporal muscles. The con- dyloid process is situated behind the sigmoid notch, and arises from the ramus by a narrow neck, which is directed upwards and a little inwards, swelling above into an oval head or condyle, that has an articular surface on its summit. This articular surface is trans- versely oval, convex, covered in the recent subject with cartilage, and inclines from within outwards and a little forwards. The condyle, from the direction of its neck, somewhat over- hangs the internal surface of the ramus; it is articulated with the anterior division of the glenoid cavity of the temporal bone. The direction and form of its articular surfaces are calculated to facilitate the rotatory move- ments of the lower jaw during mastication. In front the neck of the condyle presents a depression for the attachment of the external pterygoid muscle. Structure. — The lower jaw is formed of two complete plates, united by cancellous tissue, which is traversed by a long curved canal (the inferior dental canal), which conveys the vessels and nerves that supply the teeth. This canal commences in a groove just above the superior dental foramen, which is situated on the internal surface of the ramus ; it then enters the substance of the bone, taking the course of the internal oblique line below, and parallel to which it runs as far as the second bicuspid tooth, where it divides into two canals, one short and wide, which terminates on the external surface of the bone at the inferior dental foramen ; and another smaller one, which continues onwards as far as the middle incisor tooth, where it ceases. From the upper side of this dental canal small tubes arise, which proceed to the alveoli ; they convey vessels and nerves to the fangs of the teeth. The situation and size of the dental canal vary according to the age of the individual. At birth it runs near the lower border of the bone, and is of considerable magnitude; after the second dentition it becomes placed just below the mylo-hyoid ridge ; in the edentulous jaw it runs along the alveolar border of the bone, its size is much diminished, and the mental foramen is found close upon the upper border of the bone. Connexions and uses.- — The lower jaw is arti- culated with the temporal bones, and receives the sixteen inferior teeth. It gives attachment to fourteen pairs of muscles, viz. the temporal, the masseter, the two pterygoids, the bucci- nator, the superior constrictor of the pharynx, the depressor anguli oris, the depressor iabii inferioris, the levator menti, the platysma, the genio-hyo-glossus, the genio-hyoideus, the mylo-hyoideus, and the digastric. Four pairs of ligaments are attached to it, viz. the external and the internal lateral ligaments of the tem- poro-maxillary articulation, the pterygo-maxil- lary (or intermaxillary) ligament, and the stylo- maxillary ligament. It forms the lower part of the face and the cavity of the mouth ; it protects the tongue, salivary gland, and pharynx ; it differs from the upper jaw and from all the other bones of the head in its remarkable mobility ; and it contributes essentially to mastication as well as to deglutition and articulation. Development.- — The lower jaw at birth con- sists of two lateral halves, which are united vertically in front along the median line by a piece of cartilage, forming what has been improperly called a symphysis. A few months after birth the removal of this cartilage com- mences, and the two halves of the bone become united below; but not unfrequently a fissure remains above for several months. At this period the alveolar border is, like that of the upper jaw, very thick, and contains some large irregular cavities which lodge the first set of teeth. Besides the superior dental foramen there is found in the foetus another, which leads to a temporary canal that supplies the first set of teeth, and behind the alveoli of the incisors may be observed a row of holes which are said to be connected with the de- velopment of the second set of teeth. Some authors maintain that each side of the lower jaw is developed by four separate points of ossification ; but this assertion wants confirma- tion. It is certain that this bone is among those which are the most early developed, and in the embryo of two months it is already of considerable size. Its alveolar border is at first a mere groove, of which the internal margin is defective, and which gradually be- comes hollowed into separate sockets as the teeth are developed. The changes of form which the lower jaw undergoes from birth till old age depend chiefly upon the development and decay of the teeth. Some of these changes have been already noticed, and will be found to correspond with those which occur in the alveolar border of the upper maxilla; the varying form and direction of the rami and angles of the lower jaw we have noticed, and for the more detailed account of the de- velopment of this bone as connected with dentition, we refer to the article Teeth. Of the face in general. — Dimensions. — The vertical diameter of the face is the greatest, and extends in front from the nasal eminences of the frontal bone to the lower border of the symphysis menti ; this diameter decreases as we trace it backwards. The transverse dia- meter is next in length if measured at the level of the malar bone, where it is most con- siderable; below and above this it gradually diminishes. The antero-posterior diameter is greatest at the level of the cheek-bones, where it extends from the cuneiform process of the occi- pital boneto the anterior nasal spine of the upper 216 FACE. maxilla ; this diameter also diminishes both above and below, but more especially below, where it comprises merely the thickness of the mental portion of the lower jaw. The bones which form the upper jaw are united with those of the cranium above by a very irregular surface ; below they are on a level with the occipital foramen, and hence that part of the face which descends below the cranium is formed exclusively by the lower jaw. The area of the face, as presented by a vertical longitudinal section of the skull, is of a triangular figure, and forms (the lower jaw excepted) in the European about one- fifth of the whole area of the skull ; in the Negro the area of the face increases in propor- tion, and forms two-fifths of the whole. The bones of the face form, when united, a pyramid with four irregular surfaces or regions, and presenting a base above, which is connected with the cranium, an apex below at the chin. The anterior surface or facial region presents many varieties of form and proportion in different individuals, as well as others more important, which characterise the various races of mankind : (see the article Man.) This region is bounded above by the lower border of the frontal bone, extended between its two external angular processes: laterally it is limited by lines drawn from these processes to the anterior inferior angles of the malar bones : below this it follows the curve of the malar ridge of the upper maxilla, and it terminates at the outer extremity of the base of the lower jaw. This surface presents from above downwards along the median line, the fronto-nasal suture, which is continued laterally into the fronto-maxillary and fronto-ethmoidal sutures, all contributing to form the common transverse facial suture which unites the bones of the cranium and face. Below the fronto-nasal suture the nasal bones, united by the nasal suture, form the prominent arch of the nose in conjunction with the nasal processes of the upper maxillary bones, with which the ossa nasi articulate on each side by the naso-maxillary suture. Below the nasal bones is the anterior orifice of the nasal fossae, of apyriform shape, narrow above, broad inferiorly, where it terminates in the projecting anterior nasal spine : the margins of this orifice are sharp, and are formed by the nasal and upper maxillary bones. Below the nasal spine is the intermaxillary suture, which terminates on the alveolar border of the upper jaw between the middle incisor teeth : on each side of this suture is the myrtiform fossa. On the lower jaw is observed, in the median line, the mental ridge and process, and on each side of it a depression for muscles. The facial region presents from above down- wards, on each side, the aperture or base of the orbit, of a quadilateral form, and in- clining from within outwards and a little back- wards. The margin of this opening is formed above by the supra-ciliary ridge of the frontal bone, in which is observed the supra-orbitar notch or foramen. At the outer extremity of this ridge is the fronto-jugal suture, uniting the external angular process of the frontal bone with the frontal process of the malar : below this is the prominence of the cheek and the curved orbitar border of the malar bone, forming the outer and lower part of the margin of the orbit. Internal to this we find the short orbitar border of the upper maxillary bone, which presents at its nasal end the groove for the lachrymal sac. Below the inferior border of the orbit is the infra- orbitar foramen, to the outer side of which is the oblique jugo-maxillary suture, and below it the canine fossa, bounded exter- nally by the malar ridge, in front by the canine ridge and the anterior orifice of the nose, and below by the alveolar border of the jaw and by the teeth. On the lower jaw we find the teeth, the alveolar ridges and depressions, the mental foramen, and the ex- ternal oblique line. The posterior or guttural surface consists of three parts, two of which, the upper and lower, are vertical ; the middle is horizontal. The upper vertical portion presents along the median line the oblique posterior border of the vomer, which divides the posterior apertures of the nasal fossae; above is the articulation formed by the base of the vomer and the sphenoid ; below is the posterior nasal spine formed by the united palate bones. At the sides of the vomer are the oval posterior orifices of the nose, greatest in their vertical diameter, and bounded superiorly by the sphenoid and sphenoidal processes of the palate bones, inferiorly by the palatine plates of the same bones, internally by the vomer, and externally by the pterygoid processes. On the outside of these apertures are placed the pterygoid fossae, formed by the pterygoid plates of the sphenoid and by the pyramidal process of the palate bone. External to these are the large zygomatic fossae or spaces, which belong to the lateral regions of the face. The horizontal portion of this surface is oval, concave, rough, and forms the roof of the mouth, consisting of the palatine plates of the palate and upper maxillary bones, on which is seen a crucial suture, formed by the longitudinal and transverse palatine sutures. At the posterior and outer angles of this hori- zontal portion are situated the posterior palatine canals and the grooves which proceed from them along the roof of the mouth ; on the inferior surface of the palate bones are ridges and depressions for the attachment of muscles, while behind the middle incisor teeth is placed the anterior palatine foramen. At the sides and in front the palatine arch is bounded by the alveolar border and teeth of the upper jaw, behind which descend the pterygoid pro- cesses of the sphenoid and palate bones. The inferior vertical division of this region is formed by the inner surface of the lower jaw and teeth ; it presents in front, along the median line, the inner mental ridge, and the genial processes ; external to these the internal oblique lines, the sublingual and submaxillary fossae, the superior dental foramen, its groove FACE. 217 and process; the condyles and angles of the jaw, its alveolar border and its base, which terminates it below, and near which, at the chin, are seen the depressions for the digastric muscles. The lateral or zygomatic surfaces on each side are bounded above by the temporal border of the malar bone and by the zygomatic arch ; in front by a line extended vertically from the external angular process of the frontal bone to the base of the lower jaw, and behind and below by the free border of the body and ramus of the inferior maxilla. This region presents a superficial and a deep portion : the former comprises the lateral aspect of the malar bone, the zygomatic arch, and the external surface of the ramus of the jaw. On it we may remark, proceeding from above downwards, the temporal border of the malar bone and zygoma, forming the outer boundary of the temporal fossa; the external malar holes, the zygoma and its suture, which unites the malar and temporal bones; the inferior or masseteric border of the zygoma, the sigmoid notch of the lower jaw and the outer surface of its ramus, coronoid and condyloid processes and angle. The deeper division of this region presents the large zygomatic fossa, and is situated internal to the ramus of the jaw, which forms its outer boundary, and which must be removed to expose it completely : this done, the fossa is brought into view, bounded in front by the posterior surface of the upper jaw and part of the malar bone ; superiorly by the inferior surface of the great wing of the sphe- noid below its temporal ridge; at this part of the fossa are seen the spheno-tempoval suture, the spinous process, and the spinous and oval foramina of the sphenoid bone. The narrow inner boundary is formed by the external ptery- goid plate of the sphenoid ; behind and below the fossa is open. At the bottom of the zygo- matic fossa is situated the pterygo-maxillary fissure, forming the external orifice of the spheno-maxillary fossa, which is a cavity situated between the tuberosity of the upper jaw in front, and the pterygoid process and palate bone behind : in this fossa are five holes, viz. three which open into it from behind, the foramen rotundum, the vidian or pterygoid, and the pterygo-palatine ; one opening inter- nally at the upper part ; the spheno-palatine ; one below, the upper orifice of the posterior palatine canal. The zygomatic fossa presents also at its upper and anterior part, the spheno- maxillary fissure, which is directed from within outwards and forwards, and is formed inter- nally by the orbitar processes of the palate and upper maxillary bones, externally by the orbitar plate of the sphenoid, atid at its outer extremity, which is large, by the malar bone; it forms a communication between the orbit and the zygo- matic fossa. Its inner end joins the sphenoidal and the pterygo-maxillary fissures, with the former of which it forms an acute, and with the latter, a right angle : thus these three fissures may be considered as branching from a common centre at the back of the orbit; they give passage to a number of vessels and nerves, and establish communications between the cavi. ties of the face and cranium. The superior or cranial region is very irregu- lar, and is immoveably united to the cranium. It presents along the median line, from before backwards, the articulation of the nasal bone, with the nasal spine of the frontal, the union of this spine with the perpendicular plate of the ethmoid, the articulation of this plate with the vomer, the articulation of the vomer with the sphenoid. Along the sides, from within outwards, are seen the arched roof of the nasal fossae formed in front of the nasal bones, in the middle by the cribriform plate of the ethmoid, and behind by the body of the sphenoid. External to these parts are found the base of the pterygoid process, the articulation of the palate with the body of the sphenoid bone, the pterygo-palatine canal, the spheno-palatine foramen ; next the spongy masses of the ethmoid united behind with the sphenoid, and anteriorly with the os frontis; and still more forwards are seen the articula- tions of this bone with the lachrymal, upper maxillary, and nasal. To the outer side of these articulations is the triangular roof of the orbit, limited externally by the sphenoid and malar bones and by the sphenoidal fissure. Next may be observed the orbitar plates of the sphenoid, forming the greater part of the outer wall of the orbit, and lastly the zygoma. The inner border of the orbitar plate of the frontal bone presents the fronto-lachrymal and the frontal-ethmoidal sutures ; the outer border the spheno-frontal and fronto-jugal sutures. The internal structure of the face appears to be very complex, presenting several cavities and divisions which give it at the same time strength and lightness. The arrangement of these parts may be understood by observing, 1. the perpendicular septum formed by the ethmoid and vomer, which divides the upper part of the face into two equal halves; 2. in each half three horizontal divisions, viz. an upper or frontal, which separates the cranium from the orbit ; a middle or maxillary, placed between the orbit and the cavity of the nose, and an inferior or palatine situated between the nose and mouth; 3. three outer divisions, viz. an upper or spheno-jugal, forming the outer wall of the orbit, and separating that cavity from the temporal fossa; a middle, formed by the maxillary tuberosity which separates the cavity of the nose from the spheno-maxillary and zygomatic fossae ; an inferior, formed by the ramus of the jaw; 4. above and at the centre the ethmoid and lachrymal bones sepa- rate the orbits from each other and from the cavities of the nose. The principal cavities of the face are the orbits, the nasal fossae, and the mouth ; and with these all the rest are more or less con- nected. These cavities will be described under the several articles, Orbit, Nose, Mouth. Mechanism of the face. — The face forms a structure which combines both strength and lightness ; the former quality is owing to the arched form of its exterior and to the strong pillars of supports (to be presently described) 213 FACE. which connect its different parts to each other and to the cranium. The lightness of the face depends upon the thinness of some of its bones, and the large cavities which it com- prises. The two upper maxillary bones form by their alveolar border and palatine arch a strong platform, from which ascend five osseous pillars; one median, formed by the vomer and the perpendicular plate of the ethmoid; two at the sides of the nose, formed by the nasal process of the superior maxilla ; and at the lateral parts of the face two others, formed by the malar processes of the upper jaw and the malar bones. All these pillars connect the upper jaw with the bones of the cranium, and contribute by their form, strength, or extent of articulation to resist or diffuse the concussion of violent blows applied to the face. The strength of the lower jaw depends upon its arched form and upon its mobility, but, from its exposed situation, it is notwithstand- ing frequently broken. Development of the face. — The development of the face consists not merely in its general increase, but in the relative proportion of its several parts at different periods of life. As the face contains the organs of sight, smell, and taste, together with those of mastication, we shall not expect to find it much deve- loped in the foetus and infant while these parts are scarcely called into action ; accord- ingly, we observe the vertical diameter of the face (strictly so called) to be very short, which is owing to the slight elevation of the ethmoid, the lachrymal, the upper and the lower maxil- lary bones, consequent on the imperfect deve- lopment of the nasal cavities, the maxillary sinuses, and the teeth; see Jig. 131. The Fig. 131. orbits, indeed, are remarkably large, but this depends upon the great development of the cranium and the breadth of the orbitar plates of the frontal bones, for in their vertical dia- meters the orbits are not remarkable at this period of life. The transverse diameter of the face in the fetus is considerable across the orbits, but below these it is narrower in proportion than in the adult. The other chief peculiarities of the fetal face are, the small size of the nasal cavi- ties, the absence of the canine fossa?, depend- ing partly on the small vertical diameter of the upper jaw, and partly upon the teeth being still lodged withm it; the prominence and shortness of the alveolar borders of both jaws, the vertical direction of the symphysis menti, which even inclines from above downwards and a little backwards; the remarkable con- vexity of the maxillary tuberosities, owing to the teeth being lodged within them ; and the great obliquity from above downwards and forwards of the posterior apertures of the nose, arising from the smallness of the maxillary sinuses; the small antero-posterior diameter of the palatine arch, which depends upon the same cause; and, finally, the oblique direction of the rami of the lower jaw : see Jig. 377, vol. i. p. 742. In the adult, as the ethmoid and turbinated bones together with the maxillary sinuses become developed, the nasal cavities enlarge, especially in their vertical diameter; above, they communicate with the frontal sinuses, which are now fully formed and projecting ; the jaws have become deeper from the protru- Fig. 132. sion of the teeth, which cause a considerable addition to the vertical diameter of the face ; below, the palatine arch has extended back- wards with the development of the maxillary sinuses, and the posterior apertures of the nose have become in consequence nearly vertical : the rami of the lower jaw form also nearly a right angle with its body. In old age the vertical diameter of the face decreases in consequence of the loss of the teeth and the contraction of the alveolar borders of the jaws, which touch each other when the mouth is closed; the rami of the jaw resume the oblique direction of childhood, (Jig. 133;) Fig. 133. FACE. 219 and the symphysis inclines from the shrunken alveolar border downwards and forwards to the base of the bone, and gives to the chin the projecting appearance which is so character- istic of this period of life. The art iculations of the face comprise those of the upper and that of the lower jaw. The articulations of the bones of the upper jaw with each other and with those of the cra- nium are all of the kind called suture, but they present considerable variety in the extent, form, and adaptation of their articular surfaces. Those bones of the face which contribute to form its columns of support, and to which this part of the head owes its strength and resistance to violence, have their articular surfaces for the most part broad and rough, presenting emi- nences and depressions which are adapted to those of the contiguous bone; examples of this firm articulation are seen, 1. at the anterior part of the intermaxillary suture, where the two palatine plates unite and form the horizontal column or base of the upper jaw; 2. at the nasal columns, where the nasal bones and the nasal processes of the upper maxillae unite with the frontal ; 3. on the sides of the face, or where the bones form their lateral or malar columns, viz. at the jugo-maxillary and jugo- frontal articulations. The spheno-jugal articu- lation, seen within the orbit, and the zygomatic or temporo-jugal, though formed by the union of comparatively narrow surfaces or borders, derive strength from their irregularity, and, in the case of the zygomatic suture, from its in- dented form, which maintains its security from vertical blows, as the curved direction of the zygoma protects it from lateral injury. Those sutures of the face which are, strictly speaking, harmonic, are such as are not exposed to any considerable pressure ; they present, nevertheless, some varieties in their mode of juxta-position. In some the adaptation is direct, as in the pterygo-palatine. In others one border or surface is received by another (schindylesis ), as in the articulations of the vomer with the sphenoid above, and with the groove in the palatine plates of the upper max- illary and palate bone inferiorly. Sometimes the surfaces are simply applied against each other, as the nasal plate of the palate bone on the nasal surface of the upper maxillary. Lastly, the edges may alternately overlap each other, as those of the nasal and upper maxillary bones. In all the sutures of the face, whatever may be the adaptation of the osseous surfaces, we find interposed a thin layer of cartilage uniting the contiguous surfaces of the bones. This is easily shown in some of the sutures by mace- ration, and only disappears in places as some of the bones become united with advancing age. The great number of pieces of which the upper jaw consists, and the varying form and direction of the sutures, all contribute, with the figure of the bones themselves, to give strength to this part of the skull, and to break the force of blows by diffusing them over- a widely ex- tended surface. The sutures of the face derive their names from the bones which contribute to form them; thus we have between the orbits the fronto- nasal, fronto-maxillary, and fronto-lachrymal sutures, all contributing to form part of the transverse suture. (See Cranium.) Lower down we find the nasal, the naso-maxillary, and the laehrymo-maxillary, which turns at right angles backwards along the inner wall of the orbit into the ethmoido-maxillary and pa- lato-orbitar sutures. On the outer side of the orbit may be observed the frorito-jugal and spheno-jugal sutures ; on the zygomatic arch the temporo-jugal suture; and below the pro- minence of the cheek, the jugo-maxillary suture, which is seen both on the anterior and posterior surface of the upper jaw. On the roof of the mouth are seen the longitudinal and the transverse palatine sutures, the former formed by the intermaxillary in front, and by the inter-palatine suture behind : the latter is often termed the transverse or horizontal palato- maxillary suture. There are some other sutures within the nose which it is unnecessary to enu- merate. The lower jaw articulates with the cranium by diarthrosis : this important joint will be particularly described in the article Temporo- MAXILLAKY ARTICULATION. The bones of the face are invested with periosteum or a fibrous membrane, which is variously modified and arranged in the orbits, nose and mouth, &c. ABNORMAL CONDITIONS OF THE BONES OF THE FACE. In the true acephalous foetus the bones of the face as well as those of the cranium are of course wanting, but the former are generally found in what are termed the false Acephalia (see Abnormal Conditions of the Cranium) ; it sometimes happens, not- withstanding, that the bones of the face are but imperfectly developed, presenting a variety of conformations which it is unnecessary to parti- cularise. The bones of the face, in some cases alone, and in others in conjunction with those of the cranium, not unfrequently acquire a de- gree of development quite disproportionate with the rest of the skeleton. In Corvisart's Journal de Medecine the case of a Moor is cited, whose head and face were so enormous that he could not stir abroad without being followed by the populace. It is related that the nose of this man, who was half an idiot, was four inches long, and his mouth so large that he would bite a melon in the proportion that an ordinary per- son would eat an apple. I have now before me the skull of a native of Shields, who was remarkable during life for the length of his face ; the entire head is large, but the bones of the face, and particularly the lower jaw, are enormously long. The abnormal development of the facial bones generally affects one jaw only, and more frequently the lower, as in the example just mentioned. Othercases, but they are much more rare, have been related in which the lower jaw was disproportionately small. When, from either of the circumstances 220 FACE. which have been just mentioned, the develop- ment of the two jaws is unequal, the corre- spondence of their alveolar borders is lost, and mastication becomes in proportion imperfect : in mammiferous animals the unequal size of the lower jaw, by preventing suckling, is often a cause of death. The bones of the face are much more symmetrical than those of the cra- nium, and rarely present the disproportion in their lateral development which is observed in the latter. Under the head of defect or arrest of deve- lopment may be noticed, 1. the occasional ab- sence of some of the bones, as for example, the lachrymal or the vomer; 2. the existence of fissures, or non-union of the upper maxillary bones, and, as a more rare case, the separation of the two halves of the lower jaw. Fissures of the upper jaw may exist in various degrees, and may occur with or without a corresponding cleft in the soft palate and lip ; it may appear as a mere slit along the middle of the roof of the mouth, forming a narrow communication between that cavity and one side of the nose ; or it may extend along the whole of the pala- tine arch, and be continuous behind with a similar division of the soft palate, without, at the same time, being accompanied with hare- lip. Sometimes the aperture is very wide, and the palatine plates of the upper maxillary and palate bones are almost entirely wanting ; in this case the vomer and middle cartilage of the nose are also partially or entirely absent; and there is both hare-Hp and cleft of the soft palate, so that the mouth, both sides of the nose, and the pharynx are laid into one great cavity. When the fissure exists at the anterior part of the palate only, it almost invariably occurs at the suture which has been described between the maxillary and intermaxillary bones, so that the cleft separates the canine from the lateral incisor tooth ; when the fissure occurs on both sides of the face, the four incisor teeth are separated from the others and lodged in an alveolar border, which usually in this case projects more or less towards the lip, in which there is also commonly a single or double cleft or hare-lip. Sometimes the fissure occurs in the intermaxillary bone itself between the lateral and middle incisor teeth, and then we find a single incisor on one side and three on the op- posite : it is very rarely that the cleft exists in the median line between the two intermaxillary bones. Among the arrests of development which occur in the bones of the face may be enume- rated a fissure which occasionally extends across the lower border of the orbit, and a suture which sometimes divides the os jugum into two pieces. The union which not unfrequently takes place between the bones of the upper jaw by the obliteration of their sutures, is commonly the effect of age, and usually occurs between the bones of the nose, between the vomer and sphenoid, and between the inferior turbinated and upper maxillary bones. Wounds and frac- tures of the bones of the face readily unite. Those most subject to these injuries are such as are the most prominent, viz. those of the nose, cheek, and lower jaw ; the last is the most frequently broken. The alveolar pro- cesses and the delicate bones in the orbit and nose are also liable to injury. The bones of the face are subject, like the rest, (though not so commonly as those of the cranium,) to hy- pertrophy and atrophy. Exostosis appears most frequently on the upper jaw, in the orbit, or along the alveolar border on the outer surface of the bones ; on the lower jaw it is situated usually along the alveolar border, at the angle or on the body of the bone. Inflammation of the periosteum and bones of the face occurs spontaneously or as the result of injuries or disease, and presents the usual phenomena. Abscesses also take place either within the cancellous structure of the more solid bones, or in the cavities which they contain ; when matter forms within the antrum, it may be evacuated by extracting the canine or the large molar tooth, which often projects into this ca- vity, and then piercing through the bottom of their sockets. When necrosis affects the bones of the face, its ravages are seldom repaired (as in the case of cylindrical bones) by the pro- duction of new osseous matter ; some attempts at reparation after the separation of a seques- trum have been, however, observed in the lower jaw. Caries, either simple or connected with syphilitic or strumous disease, may attack nearly all the bones of the face, but it more particularly affects the alveolar borders of the jaws and the delicate bones about the nose and palate ; it is often attended with partial ne- crosis. Caries of the face may occur as the re- sult of malignant ulcerations, of lupus, or of the various forms of cancer which affect the soft parts. Both the upper and lower jaw are sub- ject to osteosarcoma, commencing either on the surface or in the interior of the bones, and ac- quiring sometimes an enormous size, so as to encroach on the orbit, nose, and mouth, and materially to impede the motions of the lower jaw. For these growths and others more sim- ple, of a fibrous or fibrocartilaginous structure, large portions (sometimes amounting to nearly the whole) of the upper or lower jaw have been removed with success. Cyst-like tumours, con- taining a serous fluid, have been found in the lower jaw. The more intractable diseases of medullary sarcoma undjungous growths of va- rious kinds also attack the bones of the face. A few cases of hydatids (the acephalo-cystus) have been met with in the upper jaw. THE MUSCLES OF THE FACE are arranged around the orifices of the eyelids, the nose, and the mouth, and may be divided into constrictors and dilators of these apertures. The nostrils, however, undergo but little vari- ation in their dimensions, being maintained permanently open by the elastic cartilages which form them. The eyelids also contain elastic cartilages, which are moulded upon the front of the globe over which they glide in obedience to the muscles which dilate or con- tract the orifice between them. The mouth, which is the most mobile of the facial aper- FACE. tures, is also furnished with its contractor or sphincter muscle, and with many dilators which radiate from it at various angles. All the muscles of the face are superficially situated, and most of them are subcutaneous. In the palpebral regions, or about the eye- lids on each side, are placed, 1. a constrictor, or the orbicularis palpebrarum, of which the corrugator supercilii is an associate; 2. the levator palpebral and the occipito-frontalis, which are dilators, and antagonists of the two former muscles. The orbicularis palpebrarum, (naso-pulpebral, Chauss.) is a flat oval muscle, situated im- mediately underneath the skin, to which it adheres, and covering the base of the orbit and the superficial surface of the eyelids ; in the middle it presents a transverse aperture, which is the orifice of the palpebral, varying in size according to the individual, and giving apparently a greater or less magnitude to the globe itself, which, however, is of nearly uni- form dimensions in different persons. The orbicularis, like the other sphincter muscles, consists of concentric fibres, but it is peculiar in having a fixed tendon on one side, from which a great part of the fibres arise ; this tendon of the orbicularis, or ligamentum pal- pebrae, which is situated horizontally at the inner corner of the eye, is about two and a half lines in length, and half a line in breadth; it arises from the anterior border of the lachry- mal groove in the nasal process of the upper maxillary bone, and passing horizontally out- wards in front of the lachrymal sac, divides into a superior and an inferior slip, which are attached to the inner extremities of the corres- ponding eyelids. The tendon at first is flat- tened anteriorly and posteriorly, but afterwards becomes twisted so as to present horizontal surfaces. From its posterior part is detached a slip of fibres (the reflected tendon of the orbicularis), which proceeds backwards to- wards the os unguis, and forms the outer wall of the lachrymal canal. The orbicularis arises, 1. from the borders and surfaces of this tendon and from its reflected slip ; 2. from the internal angular process of the frontal bone and from the fronto- maxillary suture ; 3. from the nasal process of the upper maxillary bone ; and, 4. by short tendinous slips from the inner third of the lower border of the orbit. From these origins the upper and lower fibres of the muscle take a curved direction outwards, their concavity look- ing towards the aperture of the lids, and fol- lowing the course of the upper and lower borders of the orbit, which they overlap. They unite at the outer side ; not, however, by a tendinous raphe or septum, as some have described, but simply by the mingling of their fibres. Each half (the upper and lower) of the orbicularis consists really of two sets of fibres ; one, which covers the margins of the orbits, and forms the circumference of the muscles, is strong, tense, and of the usual reddish colour ; it arises from the direct ten- don, and from the frontal or upper maxillary bone. These form the orbicularis properly so called. The other set, which is pale and thin, covers the lids and proceeds almost in a hori- zontal direction outwards from the palpebral bifurcation of the orbicular tendon : this forms the ciliary or palpebrales. These two sets of fibres, as we shall presently see, are distin- guished as much by their functions as by their appearance. Relations. — The superficial surface of that part of the muscle which covers the lids (the palpebrales) is connected to the skin by delicate loose cellular tissue entirely destitute of fat. The stronger fibres which form the outer part of the muscles are closely adherent to the integument by cellular tissue more densely woven, and presenting more or less fat. The posterior surface covers, above, the lower part of the frontalis and the corrugator supercilii, with whose fibres it is connected ; internally the corresponding part of the fibro- cartilages of the lids, the lachrymal sac, and the inner border of the orbit externally, the outer border of the orbit and part of the tem- poral fascia inferiorly, the upper part of the malar bone, the origins of the levator labii superioris proprius, the part of the levator labii superioris alaeque nasi, and the inferior border of the orbit. At its circumference this muscle corresponds, by its upper half, to the frontal, which it slightly overlaps, and inter- nally to the border of the pyramidalis, with which it is connected ; externally it is free. Below its border is free, covering the origin, and giving some fibres to the lesser zygomatic ; and internally it is separated from the levator labii superioris alaeque nasi by cellular tissue, in which runs the facial vein. The central fibres cover the palpebral fascia and the lids, which separate them from the conjunctiva. Action. — The action of this muscle resem- bles that of other sphincters, the curved fibres in contraction approaching the centre ; but as in the orbicularis palpebrarum these fibres are fixed at the inner side, it follows that the skin to which the muscle is attached by its anterior surface is drawn towards the nose, and when the muscle is in strong action, becomes cor- rugated, presenting folds which converge to- wards the inner angle of the eye ; above, where the effect of the muscle on the skin is most marked in consequence of its closer connec- tion with the integuments, the brow and the skin of the forehead are drawn down by it and its associate the corrugator; the lower fibres when in strong action, draw the cheeks upwards and inwards. Like the other sphinc- ters, also, this is a mixed muscle. Those fibres which may be supposed to be voluntary, are the larger and outer ones, which corres- pond to the border of the orbit, and are of a red colour. The involuntary fibres are those thin ones which cover the lids, are of a pale colour, like the muscles of organic life, and arise from the palpebral subdivisions of the horizontal tendon. They contract involuntarily while we are awake, in the action of winking, and during sleep in maintaining the lids closed; they also act under the will in closing the lids, particularly the upper. It appears then 225 FACE. that the orbicularis may be divided both ana- tomically and physiologically into two sets of fibres; an outer, or orbicularis proper, which is entirely a voluntary muscle, and an inner (the palpebrals) which is both voluntary and involuntary in its action. These fibres may act independently of each other, for in wink- ing and during sleep the palpebralis contracts, while the orbicularis is quiescent ; and the orbicularis may contract even strongly, as when we peer with the eyes under the influence of a strong light, while the fibres of the pal- pebrals are relaxed. It has been supposed, however, by some, that during sleep the lid is closed simply by the weight of the upper palpebra, and the relaxation of its proper elevator muscle, but this seems in contra- diction to the fact that we meet with resistance in endeavouring to unclose the lids of a sleep- ing person. Corrugator supercilii, which is the associate of the orbicularis palpebrarum, has been al- ready described, together with the occipito- frontalis, which is the antagonist of those muscles. See Cranium, muscles of the, vol. i. p. 747. Levator palpebra superioris ( orbito-palpe- bral ), though situated within the orbit, is nevertheless the direct antagonist of the palbe- bralis, and is therefore properly described with these muscles of the face. It is a thin trian- gular muscle, which arises by a narrow slen- der tendon at the back of the orbit from the inferior surface of the lesser wing of the sphe- noid bone, above and in front of the optic foramen ; from this origin the fibres proceed almost horizontally forwards under the roof of the orbit, and gradually spreading and be- coming thinner as they advance, curve over the globe of the eye, and are inserted into the upper border and anterior surface of the upper lid. Relations. — Its upper surface is in contact, behind, with the frontal branch of the ophthal- mic nerve, which with some cellular tissue alone separates it from the periosteum of the roof of the orbit ; anteriorly with cellular tissue and the palpebral fascia, which separate it from the orbicularis. The lower surface behind rests upon the superior rectus oculi, with which it is connected by cellular tissue, and anteriorly on the conjunctiva and upper lid. Its action is to raise the upper lid, and to draw it backwards over the globe and under the supra-ciliary ridge. There is no separate muscle to effect the depression of the lower lid, that action being occasioned, as Sir C. Bell ingeniously suggested, by the protrusion of the eyeball. Nasal region. — The muscles of this region, some of which are common to the upper lip, are, 1. the pyramidalis ; 2. the levator labii superioris alaque nasi; 3. the triangularis nasi; 4. the depressor ala nasi. Pyramidalis is situated between the brows, and may be considered as a prolongation of the inner fibres of the frontalis : it is of a triangular form ; its base above is continuous with the fibres of the frontalis; below it con- tracts and is inserted into the aponeurotic ex- pansion of the triangularis nasi. It is sepa- rated from its fellow slip of the opposite side by a groove of cellular tissue. Relations. — Its superficial surface adheres to the skin ; its deep one rests on the nasal eminence of the frontal bone, the nasal bones, and part of the lateral cartilage of the nose. Use. — If this muscle acts at all on the nose, it is by drawing up the skin when the occipito- frontaiis is in action. Its more probable use is to give a fixed point to the frontalis, and to draw down the inner extremity of the brows and the skin between them. Levator labii superioris alaque nasi. — (I', fig. 134.) This is a thin, long, triangular Fig. 134. muscle, placed nearly vertically on each side of the nose. It arises narrow from the outer surface of the nasal process of the upper max- illary bone, immediately beneath the tendon of the orbicularis palpebrarum. It descends obliquely outwards, becoming broader, and terminates inferiorly by two slips, an internal short one, which is attached to the cartilage of the ala nasi, or to the fibrous membrane which invests it ; and an outer longer slip, which is attached to the skin of the upper lip near the nose, and mingles its fibres with the transversalis nasi, the levator labii superioris proprius, and the orbicularis oris. Relations. — Covered by the skin, and over- lapped a little above by the orbicularis pal- pebrarum, this muscle covers the nasal process of the upper maxillary bone, the triangularis nasi, and the depressor ala nasi. Its inner border above corresponds to the pyramidalis. Its action is to raise the ala of the nose and the adjacent part of the upper lip; in so doing it dilates also the nostril and becomes a muscle of inspiration. When strongly thrown into action, it corrugates the skin of the nose trans- versely. FACE. 223 Triangularis nasi ( transversalis nasi, com* pressor naris, Albin.) ( n, fig. 134), is a very thin triangular muscle, placed transversely on the middle of the side of the nose. To expose its origin, the levators of the upper lip must be turned aside, and the skin of the nose very carefully dissected off'. Its origin is then seen as a narrow slip from the inner part of the canine fossa, below the ala nasi ; from this point the fibres radiate inwards and upwards, and expand into a very thin aponeurosis, which crosses the ala nasi and the lateral car- tilage of the nose to be confounded along the median line with that of the opposite muscle, and with the pyramidalis. Bourgery describes two other origins, one superficial, attached to the skin below and to the outside of the ala nasi, and a middle one crossing and connected with the fibres of the levator of the upper lip. Relations. — It is covered at its origin by the levator labii superioris alreque nasi, and inter- nally by the integuments to which it super- ficially adheres ; it rests on part of the upper jaw, on the cartilages of the ala, and on the lateral cartilage. Its action is yet undetermined by anato- mists, some considering it a compressor or constrictor of the nose, others as a dilator or elevator. Cruveilhier thinks that its action varies with the form of the ala, which, when convex, makes it a compressor, when concave a dilator. Perhaps, as M. Bourgery suggests, its action depends upon which extremity is fixed, and that, when its base is fixed, its superficial fibres dilate the nostrils and draw the lip upwards and inwards, and that, when the muscle acts towards its maxillary attach- ment, it compresses the nostril. Depressor ala nasi ( musculus myrtiformis ), (fig. 134.) To expose this muscle the upper lip should be reversed, and the mucous mem- brane divided on each side of the franum labii. It is a short flat muscle, radiating upwards from the myrtiform fossa of the upper jaw, where it arises towards the ala of the nose, into the posterior part of which it is inserted below and internal to the dilator nasi. This muscle really consists of two sets of fibres, one which has been just described, the other which is in front of this and is attached above to the ala and septum of the nose, below to the inner surface of the orbicular fibres. The first set, or the naso-maxillary fibres, are de- pressors of the alae and contractors of the nostrils ; the second, or naso-labial fibres, are elevators of the upper lip. Relations. — It is covered by the mucous membrane of the upper lip, by the orbicularis oris, and by the levator labii superioris alseque nasi ; it covers the myrtiform fossa of the upper jaw : its inner border is separated from its fellow by the franum. A dilator ala nasi is described by Bourgery as a little triangular muscle, consisting of fibres placed underneath the skin lying on the outside of the ala nasi, from the posterior part of whose cartilages the fibres arise by a narrow point, and then radiate upwards, outwards, Fig. 135. and downwards, to be mingled with the fibres of the elevators of the lip, the orbicularis, and the naso-labial, all being attached to the skin. This muscle, ^according to Bourgery, directly draws the ala outwards, and is consequently a dilator of the nostril. The labial region presents in the centre, 1. a sphincter (the orbicularis oris), with which are associated two muscles on each side, the depressor labii superioris and the levator labii inferioris : all these are contractors or com- pressors of the lips : 2. a number of anta- gonist muscles or dilators, which comprise many muscles, which on each side radiate from the lips, or from their commissure at different angles. They are, above, the levator labii superioris proprius and the zygomaticus minor; below, the depressor labii inferioris at the commissure, the buccinator, the levator anguli oris, and the depressor anguli oris. By some anatomists the muscles of this region of the face are divided into, 1. the sphincter, and, 2. the elevators and depressors of the lips. Orbicularis or sphincter oris (labial,Chauss. and Dum.) (o o, fig. 134) is a thick oval muscle, placed transversely around the aper- ture of the mouth, which varies in «ize in dif- ferent persons, but bears no relation to the size of the buccal cavity. It extends above from the free border of the upper lip to the nostrils, and inferiorly from the free border of the lower lip to the depression above the chin. Its fibres, arranged in successive layers, consist of two semi-elliptical halves, one superior, the other inferior, which are on each side united externally to the commissure of the lips by decussating each other, and mingle also at their circumference with the dilators which are attached to it. These fibres are concentric, with their curve towards the lips ; the most central run nearly in a horizontal direction along the borders of the lips, and take a di- rection forwards, which gives the prominence to the lips which is so remarkable in the Negro. The outer fibres are more curved, and receive between their layers the extensors of the lips, which are attached around them. This is the only muscle of the face which has no attachment to bone. Relations. — The anterior surface is closely 224 FACE. connected with the thick skin which covers it. The posterior surface and free border is covered with the mucous membrane of the mouth, from which it is only separated in places by the labial glands, by the coronary vessels, and by numerous nerves. Its outer border or circum- ference receives the antagonist muscles which are attached around it. Actions. — The orbicularis enjoys a very va- ried and extensive motion, and possesses the remarkable power of either acting as a whole or in parts. Its simple use is to close the mouth, in correspondence with the elevation of the lower jaw, by bringing the red borders of the lips in contact, or by pressing them to- gether firmly. But the upper or lower labial fibres can act separately, or the fibres at either commissure, or the fibres of one side may con- tract, while the others are quiescent, so that different parts of the lips may be moved by different portions of the muscle, which is made in this way to antagonize in turn the different muscles which are attached around. The lips may be thrown forward by the con- traction of the labial and commissural fibres forming in strong action a circular projection, as in the action of whistling, or, when more relaxed, in blowing. By the contraction of the inner labial fibres the lips may, on the contrary, be turned inwards so as to cover the teeth. The play of the mouth, however, which contributes in so eminent a degree to the expression of the face, depends not only on the orbicularis, but upon its association with the different muscles which are attached around it. Naso-labialis is a small subcutaneous slip of fibres, only distinctly seen in strong muscular lips. It is situated on each side of the median depression of the upper lip, and arises from the lower septum of the nose at the back part of the nostril ; it proceeds downwards and out- wards, and is soon lost in the fibres of the or- bicularis. It is an elevator of the middle part of the upper lip, and is considered by some as an attachment of the orbicularis. Levator labii superioris (I', Jig. 134) is a thin, flat, quadrilateral muscle, situated about the middle of the face, and nearly on the same plane with the levator labii superioris alaeque nasi. It arises from the malar and upper maxillary bones where they form three-fourths of the lower border of the orbit, by short ten- dinous slips ; from this origin the fibres, con- verging a little, take a direction downwards and inwards, and are inserted partly super- ficially into the skin of the upper lip, and partly into the fibres of the orbicularis, between the insertion of the levator labii superioris alaque nasi and the lesser zygomatic, with which its fibres are partly covered and con- founded. Relations. — Its anterior surface is covered above by the orbicularis palpebrarum, below by the skin and by the muscles with which its fibres are mingled at its insertion. Its posterior surface covers the infra-orbitar vessels and nerves at their exit from the infra-orbitar fo- ramen, which, with some fat and cellular tissue, separates it from the upper part of the levator anguli oris. It covers also part of the trian- gularis nasi. Its action is to raise and draw a little out- wards the upper lip. Zi/gomaticus minor (3', fig. 134) is a narrow rounded muscle, often wanting It arises from the external surface of the os malas, and fre- quently also from the deep fibres of the orbicu- laris palpebrarum, by which its origin is co- vered ; it proceeds downwards and inwards, and is attached to the skin and orbicularis pal- pebrarum above the commissure of the lips, where its fibres are also confounded with those of the levator labii superioris proprius. Relations. — This muscle is covered in front by the orbicularis palpebrarum and skin ; its posterior surface conceals a part of the levator anguli oris and of the labial vein. Action. — It is an associate of the levator labii superioris, and contributes to raise the upper lip and draw it a little outwards. Zygomaticus major (3, jig. 134), placed to the outer side and a little below the preceding muscle, is of a rounded form, and arises by short tendinous slips from a depression on the posterior part of the outer surface of the os malae, near its lower border. Its fibres proceed downwards and inwards, nearly parallel with those of the lesser zygomatic, but much longer; and expanding a little below, they become con- founded with the fibres of the orbicularis oris at their commissure, and with those of the levator labii superioris, levator anguli oris, and depiessor anguli oris. Its superficial fibres are attached to the skin. Relations. — This muscle is surrounded by fat, which separates it from the skin. By its deep surface it rests above on the os mala; and the masseter; below, it is separated by fat from the buccinator and the levator labii supe- rioris : it crosses also the labial vein. Its action carries the commissure of the lips upwards and outwards, and is intermediate between the action of the levator and the buc- cinator: it is the antagonist of the levator an- guli oris in drawing the lip outwards; its associate in raising it. When both these mus- cles act, the commissure of the lips is directly raised. Levator anguli oris ( musculus caninus): ( c, Jig. 136). — To expose this, the levator labii superioris must be removed. It is a flat qua- drilateral muscle, which arises from the middle of the canine fossa of the upper jaw, and be- coming somewhat narrower takes a direction downwards and a little outwards and forwards, to terminate at the commissure of the hps, where its fibres mingle with those of the orbi- cularis, the buccinator, and the depressor anguli oris. Relations. — Deeply placed above, its ante- rior surface is covered by the infra-orbitar ves- sels and nerves, and by fat, which separate it from the levator labii superioris and the lesser zygomatic. Below it is covered by the zygo- matics major and the integument. The pos- terior surface of this muscle rests on the upper TACK. 2-2.-. maxillary bone on the mucous membrane of the mouth, and on the buccinator. Its action is to raise the commissure of the lips, and draw it a little inwards. Its action when as- sociated with that of the zygomatics has been already explained. Depressor anguli oris (triangularis oris) (t, Jig. 134) is a thin, triangular, subcutaneous muscle, situated at the lower part of the face. It arises by a broad base from the lower border of the inferior maxilla, and from the surface of the bone between this border and the external oblique line, extending from the chin to within half an inch of the masseter. The fibres con- verge and ascend towards the commissure of the lips, the posterior fibres taking a direction upwards and forwards, the middle nearly ver- tical, and the anterior describing a curve up- wards and backwards: they all terminate at the commissure of the lips, where they become united with those of the orbicularis and of the buccinator, and more superficially with the great zygomatic and levator anguli oris. Relations. — Its superficial surface is covered by the skin and by the fibres of the platysma, with which it is mingled. Its deep surface rests upon part of the depressor labii inferioris and buccinator: above it is connected with all the muscles of the commissure and with the skin. Action. — This muscle draws down the angle of the mouth, and in this respect is the anta- gonist of the great zygomatic and levator an- guli oris. Depressor labii inferioris ( quadrutus menti), ( d, fig. 136, 137) fiat and of a square form, is placed internal to the preceding, which partly conceals it. It arises from the inner half of the external oblique line of the lower jaw, and also from the platysma, with whose fibres it is continuous. Its fibres, which are parallel, pro- ceed upwards and inwards to be attached to the lip ; the deep fibres mingle with those of the orbicularis; the superficial pass in front of that muscle, and are fixed in the skin of the lip. The inner fibres decussate above with those of the muscle on the opposite side; below, with those of the levator menti. Fig. 136. VOL. II. Relations. — At its origin this muscle is co- vered by the triangularis, and elsewhere by the skin, to which it adheres intimately above. Its deep surface covers part of the lower jaw, the mental vessels and nerves, part of the orbicu- laris oris and levator menti. Through the an- gular interval between the two depressors of the lower lip, the levatores menti pass to their insertion. Its action is to draw downwards and out- wards one side of the lower lip; if the muscles on both sides act, the lip is drawn downwards and extended transversely. The stronger ac- tions of this muscle are usually accompanied by those of the platysma, with whose fibres, as we have seen, it is continuous. Levator menti (honppe du menton ) (e, fig. 136, 137) may be exposed by everting the lip and dividing the mucous membrane: it is a small round muscle, situated at the lower part of the face, and forming on each side a great part of the prominence of the chin. It arises in the incisive fossa below the incisor teeth of the lower jaw, external to the symphysis, and pro- ceeds downwards and forwards: it passes under the lower border of the orbicularis oris, and emerging between the depressor labii inferioris, expands a little to be inserted into the skin of the chin. Its fibres below are mingled with fat ; internally they are confounded with those of the fellow muscle, and externally with the fibres of the quadratus menti. In its action this muscle raises and corru- gates the chin, and by so doing raises also the lower lip and throws it forward. Fig. 137. Buccinator (b, fig. 136, 137). This muscle is situated on the side of the cheek, and to ex- pose it completely it is necessary to divide the muscles attached to the angle of the mouth, and to remove the ramus of the jaw and the muscle attached to it. The buccinator is a broad flat muscle, and arises, 1. behind and in the middle from an aponeurotic line, the pterygo-maxillary ligament or inter-maxillary ligament, which is common to it and the su- perior constrictor of the pharynx, and which is Q 220 FACE. extended between tlie lower extremity of t!ie internal pterygoid plate of tlie sphenoid bone and the posterior extremity of the internal ob- lique line of tlie lower. Above, the buccinator arises, 2. from the outer surface of the upper alveolar process, between the first malar tooth and the tuberosity ; 3. below from the outer side of the alveolar border opposite the three last malar teeth. From these three origins the fibres proceed forwards, the superior curving a little downwards, the inferior upwards, and the middle passing horizontally towards the angle of the mouth, where they mingle with the fibres of the orbicularis and the elevators and depressors of tlie commissure. The infe- rior and superior fibres become shorter as we trace them forwards, and some of them decus- sate at the angle of the mouth to unite with the opposite labial half of the orbicularis. The fibres of the buccinator are wavy, over- lapping each other, so that they admit of great distention, which is, however, limited by a buccal fascia, which is given off from the pterygo-maxillary ligament. Relations. — The buccinator is deeply situated behind, where it is covered by the ramus of the jaw and the edge of the masseter, from which it is separated by a quantity of fat, which projects beyond the mass, fills up the hollow in front of the masseter, and is always found even in thin subjects. In the middle it corresponds to the buccal vessels and nerves and to tlie transverse facial artery, which runs nearly parallel to its fibres, and to the duct of the parotid gland, which, resting at first upon its fibres, pierces them opposite the second molar tooth of the upper jaw, and opens obliquely into the mouth. A buccal fascia covers the posterior half of the muscle. At the commissure the buccinator is covered by the muscles which are attached to the angle of the mouth, and is crossed at right angles by the external maxillary artery and vein. By its internal surface this muscle covers the mucous membrane of the mouth, from which it is only separated by a layer of buccal glands. Action. — This muscle, being fixed behind, above, and below, acts principally in front on the commissure of the lips, which it draws horizontally backwards, elongating the aperture of the mouth transversely, and throwing the cheek into the vertical folds which are so re- markable in old age. In this respect it is the direct antagonist of the orbicularis oris: if both these muscles act together, the lips are extended and pressed against the teeth. When the cavity of the mouth is distended with air or liquids, this muscle is protruded at the checks, and its fibres become separated and curved. If now the muscle acts, the fibres become straightened, and the fluid is expelled from the mouth either abruptly or gradually according to the resistance of the orbicularis. This action of the orbicularis is exemplified either in spirting fluids from the mouth, or in playing on wind instruments. In mastica- tion the buccinator presses the food from between the cheek and gums into the cavity of the mouth. It assists also in deglutition when the mouth is closed, by pressing the food backwards towards the pharynx. Among the muscles of the face, it is ne- cessary to allude to some parts of the platysma, which are not only seen in this region, but which contribute materially to the motion and expression of the face. The platysma ( p, p,p, Jig. 138) is a large, broad, membranous layer of fibres, which extend from the upper and an- terior part of the chest, where they commence in the subcutaneous tissue, upwards over the anterior and lateral part of the neck, to the jaw and lower part of the face, where they are inserted above. The whole superficial surface of the muscle is subcutaneous, but less firmly attached to the integument just under the jaw than elsewhere. The under surface of its cervical portion is in relation with numerous important parts on the face: it covers from before backwards the lower part of the chin, the quadratus menti, the triangularis oris, the base of the lower jaw, tlie facial vessels, and part of the masseter. The arrangement of its facial portion is all that need be described here. Fig. 138. ' \ '^v'vvv As the fibres of the muscle incline upwards towards the median line, they meet below the symphysis of the chin, and some ascend as high as the levator menti. Externally the fibres seem to split to enclose the depressor anguli oris, and to proceed upwards and for- wards with that muscle and the quadratus menti to the lower lip and its angle. The middle fibres are attached to the base of the jaw, and posteriorly they mount over the FACE 227 angle, and are lost on the fascia of the masseter. A curious slip crosses these transversely, de- scending a little from the fascia covering the parotid gland towards the angle of the mouth. It is the risorius Santorini, which is, however, often wanting. The platysma draws clown the whole of the lower part of the face, or, acting more slightly, depresses the lower lip and the commissure in conjunction with their proper depressors. The slip called risorius, on the contrary, raises the angle of the mouth. The only fasciae of the face are, 1. a pal- pebral fascia, which connects the convex edges of the tarsal cartilages to the border of the orbit; and, 2. a buccal fascia, which, ex- tending forward from the intermaxillary liga- ment, covers the posterior half of the buccinator muscle : anterior to this it becomes lost in the surrounding cellular tissue. General review of t lie muscles of the face. — With one exception, all the muscles of the face are attached at one part to bone, and at another either to the skin or to some other muscle : their fibres are also red and firm at their fixed attachment, pale and thinner at their moveable extremity. With the exception of the orbicularis oris, which is a symmetrical muscle, all the others are arranged in pairs, one on each side of the face. The mouth being the most moveable, has by far the greatest number grouped around it. It pos- sesses, 1. a sphincter, the orbicularis oris, the important action of which on the lips in suction, respiration, whistling, blowing, and playing on wind instruments, in speech and in expression, has already been partly spoken of. The associate of this muscle is the levator menti. 2. The antagonist of this are, a, the naso-labialis, the transversalis nasi, the levator labii superioris, both proper and common to it and the nose, and which raise the upper lip ; b, the depressor labii inferioris and pla- tysma, which draw down the lower lip ; c, the buccinator, which extends the aperture of the mouth transversely ; d, the zygomatics, the risorius Santorini, and the levator anguli oris, which draw the commissure upwards ; and, e, the depressor anguli oris and platysma, which draw it downwards. About the eyes there are on each side, 1. a sphincter, the orbicularis palpebral and pal- pebralis, with the associate, the corrugator supercilii ; 2, the dilators, the occipato frontalis and levator palpebrae. About the nose there are, 1, a constrictor, the depressor alai nasi; 2. the dilators, levator labii superioris ala?que nasi and the dilator nasi; 3. the triangularis nasi, which probably both dilates and contracts the orifice of the nostrils according to the attachment, which is fixed. The muscles of the face, including the pyramidalis, the levator palpebrae, the naso- labialis, and the dilator alae nasi, are sixteen pairs in number; if we add the occipito- frontalis, the corrugator supercilii, and the platysma, nineteen pairs, and one symmetrical, the orbicularis oris. Of these, four pairs belong to the eye, three pairs to the nose, ten pairs and one single one to the mouth : two pairs are common to the mouth and the nose. The use of the muscles of the face with respect to expression is a subject of so much interest, and involves so many collateral facts, that it will be better considered under the separate article Physiognomy. It will be sufficient to observe here that the muscles which express lively feeling and the gay passions, such as the oecipito-frontalis, the levator pal- pebrarum, the levators and dilators of the lips and their commissure, do for the most part either raise or draw the parts from the median line ; and that those muscles which manifest the sadder feelings and the darker passions, as the corrugator supercilii, the pyramidalis, the levator menti, the depressors of the lower lip and its commissure, either depress the parts or draw them from the median line. The constant and habitual exercise of either of these sets of muscles leaves corresponding permanent folds in the skin, which are in- dicative of the habitual feelings and passions of the individual. T/ie integuments of the face. — The skin of the face is, with the exception of some parts, remarkable for its tenuity, for its abundant supply of vessels, nerves, and follicles ; for the growth of hair, which covers some parts of it; and for its attachment to the subjacent muscles. The vascularity of the skin in some parts is even beautiful, tinting the cheek and lips, as in the act of blushing, assisting in the expression of the feelings and passions. The subcutaneous cellular tissue is, in general, very dense in this region, and is mingled with more or less fat, except on the eyelids, where it is loose, delicate, and quite destitute of adipose tissue. Generally speaking, the skin of the face is more adherent, and the subjacent cel- lular tissue is more dense and less fatty, along the median line than at the lateral parts ; the nose and lips offer examples of this fact. At the sides the cellular tissue is looser below, near the base of the jaw, than higher up on the cheeks. Most of the muscles are more or less surrounded with fat, which, however, par- ticularly abounds on the cheeks and between the masseter and buccinator muscles. Vessels of t lie face. — The arteries are de- rived chiefly from the external carotid, viz. 1. the external maxillary or the facial artery, and its branches; 2. branches from the tem- poral, particularly the transverse facial artery ; 3. branches from the internal maxillary, more particularly the infra-orbitar, the buccal, and the superior and inferior dental arteries ; 4. some arteries which emerge from the orbit and are derived from the ophthalmic branch of the internal carotid. These vessels communicate very freely with each other, and form with their accompanying veins an intricate vascular network over the face. See Carotid Ar» tery. The veins are principally branches of the external jugular, viz. 1. the facial vein with its branches, which correspond generally to the trunk and branches of the facial artery, except that the facial vein is rather more superficial 92 FACE. and further from the median line than the artery ; 2. the transverse facial vein and some other small branches of the temporal; 3. veins corresponding to the branches of the internal maxillary artery already mentioned ; and, lastly, some veins about the nose and brow, which are connected with the ophthalmic vein within the orbit. Both arteries and veins are imbedded in the adipose tissue, and are often remarkably tortuous, more especially the ar- teries, in old persons. Their trunks and branches open in a direction towards the me- dian line, particularly at the upper part of the face. The lymphatics are much more numerous than those of the cranium, and follow prin- cipally the course of the bloodvessels, and terminate in the submaxillary and parotid lym- phatic ganglions ; in their course they traverse some ganglions, which are situated on the buc- cinator. The superficial lymphatics arise from all parts of the face, and, accompanying the su- perficial vessels, end in the submaxillary gan- glions; some of them traverse the smaller buccal ganglions. The deep lymphatics are situated in the zy- gomatic and pterygo-maxillary fossae ; they also accompany the bloodvessels, and ter- minate in the deep parotid and submaxillary ganglions. The lymphatic ganglions of the face are prin- cipally situated along the base of the jaw, and are termed the submaxillary ganglions. Others are placed on the jaw and buccinator, in front of the masseter (the buccal ganglions), and follow the facial vessels. Some lymphatic ganglions are situated underneath the zygoma (the zygomatic ganglions) ; and others, more numerous, are placed upon, within, or under- neath the parotid gland, and are termed the parotid ganglions. The deep lymphatics of the orbits, nose, and mouth, will be described with those cavities. The nerves (tf the face are derived from the three divisions of the fifth and from the portio dura of the seventh cerebral nerves. The branches from the fifth emerge on the face, 1. from the orbit; these come from the oph- thalmic or first division of the fifth, and are the frontal, the supra-trochlear, the infra- trochlear, and the lachrymal : 2. from the infra-orbitar foramen escape the infra-orbitar nerve, from the second division of the fifth or superior maxillary, and from the same source, emerging from underneath the ramus of the jaw, the buccal nerves: 3. from the mental foramen emerge branches of the inferior den- tal nerve, derived from the third division of the fifth or the inferior maxillary ; and from the same source, piercing the masseter, the masseteric nerves. The portio dura, after turn- ing over the posterior border of the lower jaw, forms a plexus (the pes anserinus) within the parotid gland, and divides into a great num- ber of branches, which are distributed on the face, and which have received various names corresponding to the regions where they run. The branches of the fifth nerve which are dis- tributed to the face principally supply the in- teguments, and those of the portio dura the muscles. Some filaments, however, of the fifth, such as the buccal branch, derived from the ganglionous portion, supply muscles; and, on the other hand, some cutaneous twigs are sent from the portio dura of the seventh to the commissure of the lips. Both nerves freely anastomose with each other on the face. For a more particular account of these nerves and of their functions, see Fifth pair of Nerves, Seventh pair of Cerebral Nerves, and Physiognomy. Abnormal conditions of the soft parts of the face. — The muscles of the face offer nothing very remarkable in their abnormal conditions ; like others, they become much developed by constant exercise, and on the other hand, when paralytic, they waste and lose both their colour and consistence; their fibres have been ob- served occasionally to have degenerated into a fatty substance, and the trichina spiralis has also been found among them as among those of other voluntary muscles. The bloodcessels of the face are subject to no anomalies in their course which call for notice in this place. It may be remarked, however, that they vary in size in different individuals, and are sometimes superficially and sometimes more deeply situated among the soft parts around ; their tortuosity in old age has already been adverted to. Vascular nevi are not unfrequentlv found on the face, in some cases deeply situated within the cavities or underneath the bones; in others, and more commonly, they lie superficially in the skin and subcutaneous tissues. They occur of the venous, arterial, or mixed kinds. The first sometimes attain a considerable magni- tude, as I have witnessed in the case of an old woman, in whom such a naevus grew on one cheek and lip, and exceeded in size the whole face. Such swellings are easily compressed, and often produce no other inconvenience than that of their deformity and weight. The arte- rial njevus, however, and more especially when deeply seated, is sometimes a formidable dis- ease, which may involve all the surrounding structures and ultimately prove fatal. The cu- taneous capillaries of the cheeks, and about the tip and ala; of the nose, often become enlarged and varicose, presenting a peculiar appearance, which is not uncommon in hard drinkers. The lymphatic glands of the face are particu- larly liable to inflammation, enlargement, and suppuration. In scrofula they often form im- mense swellings along the base of the jaw and about the parotid gland, sometimes remaining permanently enlarged, and sometimes suppura- ting and terminating in abscesses difficult to heal. The nerves of the face are liable to be pressed upon and irritated by the enlarged glands and by the tumours in this part of the body. The face is also subject to a most distressing com- plaint, termed tic dovlouroux, which may arise spontaneously or from injury, and which ap- pears to affect particularly, if not exclusively, the branches of the fifth pair of nerves, and FASCIA. 229 more especially the infra-orbitar. Neuralgia of the lower part of the face seems, however, in some instances to follow the course of those branches of the cervical plexus which proceed toward this region. Division of the nerves, though it sometimes checks, seldom cures this painful affection, for the divided nerves spee- dily reunite, and the complaint returns ; and this takes place even after a portion of the nerve has been removed. Spasmodic affections of the face are connected with the branches of the portio dura : both nerves are of course sub- ject to palsy. The cellular tissue of the face is abundant, vascular, mingled generally with more or less fat, and in some places, as on the eyelids, is so lax as to be peculiarly liable to infiltration with fluids. Sometimes it becomes emphyse- matous, in cases of wounds of the frontal sinuses and larynx. It is easily affected by erysipelas, and is the common seat of abscesses, which, however, as there is no fascia to confine the matter, rarely attain any considerable size, but soon make their way towards the surface of the skin. When, indeed, the pus forms on the forehead between the muscles and the pericra- nium, or beneath the fascia covering the parotid gland, or beneath that investing the masseter and posterior part of the buccinator muscles, the matter being more confined is longer in arriving at the surface, and is productive of more pain than in the former instance. En- cysted tumours are not unfrequently formed in this structure of the face. The skin of the face, from its vascularity and the almost homogeneous mass which it forms with the subjacent tissues, readily unites after incised wounds, and hence the success which has attended the attempts at reparation of some parts of this region, such as the nose, cheek, and lips ; the extensibility of the skin also favours such operations. Punctured and con- tused wounds of the face are apt to produce erysipelas when they affect those parts where the cellular tissue is most dense, as on the nose and the prominence of the cheek. Abscesses are the more common result where the cellular tissue is looser. The skin of the face becomes swollen and thickened in some complaints which attack it, such as scrofula, which produ- ces enlargement of the lips and nose, and ele- phantiasis, cancer, and a few other diseases which affect it more permanently. It is sub- ject also to freckles, stains, and discolorations of various kinds, enlargement, inflammation, and induration of its follicles; to a variety of cutaneous eruptions ; to ulcerations from scro- fula, scirrhus, lupus, 8cc. which frequently make great ravages not only in the soft parts of the face, but even in the bones ; to tubercles, warts, tumours, and anomalous growths of various kinds ; and finally to boils. Its vas- cularity renders it more liable than in other parts of the body to receive the impression of small-pox pustules. Like the bones, the soft parts of the face are subject to congenital mal- formation. 1. Its apertures may be closed more or less firmly ; this happens with the eye- lids, nostrils, and lips. 2. There may be de- fects of growth, as fissures in the lips, or hare- lip, which may be single or double, and exist alone or in combination with fissures of the palate. The fissure may vary in depth, some- times, in the upper lip, extending into one of the nostrils, and at others only affecting the border of the lip. Congenital cleft of the lower lip is very rare, and is never combined with fissure of the bone. The nose is sometimes fissured, presenting no cartilaginous septum, and but one large orifice or nostril. Occasion- ally a congenital fissure has been observed in the cheek. The abnormal conditions of the teeth, the orbits and their contents, of the lachrymal apparatus, and of the cavities of the nose and mouth, will be found under the seve- ral articles on these subjects. For the BIBLIOGRAPHY of this article, see Anatomy (Introduction). (R. Partridge.) FASCIA, (in general anatomy,) (Binde, se/iinge Sc/ieide, Flechsenhdute, Germ.) This term is applied to certain membranous expan- sions, existing in various regions of the body, and forming coverings to particular parts. These expansions are composed either of cellu- lar tissue, more or less condensed, or of fibrous tissue, the former being the cellular fascia, the latter the aponeuroses or aponeurotic fascia . The structure and connexions of a considerable number of the fascia? are highly interesting, as well with reference to correct diagnosis and prognosis in surgical disease, as in regard to the mode of proceeding in various operations. 1. Cellular fascia. — These are lamellae of cellular membrane of variable density, some- times loaded with fat, at other times totally devoid of it The best example of this form of fascia is the layer of cellular membrane which is immediately subjacent to the subcutaneous cellular tissue all over the body, and in most places so intimately connected with it as to be inseparable ; these in fact form but one mem- brane, which, although essentially the same everywhere, yet exhibits characters peculiar almost to each region of the body; it is gene- rally known under the name of the superficial fascia. Although this fascia is universal, there are, nevertheless, certain regions where, from its greater importance, it has been more care- fully examined than in others, and tcwhich we may best refer in order to investigate its pecu- liar characters. Of these regions those of the abdomen and the neck stand pre-eminent ; here this fascia constitutes a distinct membranif'orm expansion, and the principal variety it pre- sents in different subjects is as regards the greater or less quantity of fat deposited in it. Where a tendinous or fibrous expansion does not lie immediately under it, this fascia sends processes from its deep surface to invest the subjacent muscles and other parts; this is very manifest in the case of the fascia of the neck ; and in general it may be stated that the super- ficial fascia has a more or less intimate connec- tion with the proper cellular covering of sub- jacent organs, whether muscles or tendon> 230 FASCIA. The arrangement to which we allude in the fascia of the neck may be satisfactorily traced from the median line on the anterior surface of the neck, proceeding outwards on each side. On the median line the fascia; of opposite sides are intimately united so as to form a dense line, called by some anatomists liiiea alba cervkulis; thence on each side the fascia divides into laminae, investing the sterno-hyoid and thyroid muscles, the carotid artery and jugular vein, the sterno-mastoid, and other muscles ; and thus anatomists come to describe a superficial and a deep layer of the cervical fascia; the former being continuous with the superficial fascia covering the muscles on the anterior part of the thorax, the latter, intimately con- nected with all the deep-seated structures in the neck, may be traced outwards behind the sterno-mastoid muscle, along the posterior edge of which it becomes again united with the su- perficial layer; the fascia, thus re-constructed, passes through the triangular space which in- tervenes between the muscle last-named and the trapezius, and may be traced over that muscle to become continuous with the superfi- cial fascia on the back. It is the deep layer of this fascia which was described by Godman of Philadelphia* as passing downwards behind the sternum to be continuous with the fibrous pericardium. This description has been sub- sequently confirmed by more than one anato- mist in France, although denied by Cru- veilhier, and in this country by Sir Astley Cooper,t who has described it in the same manner, apparently without being acquainted with the previously recorded statements of the anatomists above referred to ; I may add that I have myself in many instances proved the accuracy of Godman's description. The cer- vical fascia is continuous superiorly with the superficial fascia on the face ; and inferiorly, besides tracing it into the pectoral region, we can follow it over the shoulder into the arm. The cervical fascia, in a great part of its extent, is not, as the superficial fascia elsewhere, in intimate connexion with the subcutaneous cel- lular tissue, but is separated from it on each side of the neck by the fibres of the platysma myoides. From this brief account of the cervi- cal fascia, (we refer for the more particular description to the article on the surgical ana- tomy of the Neck,) we learn one characteristic of the superficial fascia, namely, its continuity all over the body. The superficial fascia of the abdomen has attracted the attention of anatomists and sur- geons from its connexion with all herniary tumours in that region. I n its arrangement it is much less complex than the cervical fascia, being a uniform membranous expansion spread oVer the superficial muscular and aponeurotic structures of the abomen, continuous on either side and posteriorly with the superficial fascia of the lumbar regions, and inferiorly with that of the inferior extremities. See the description of it in the article Abdomen. * Anatomical Investigations, Philiidclph. 1821. \ On ihr thymus gland. The superficial fascia of the limbs is com- pletely confounded with the subcutaneous cel- lular tissue, and wants that condensation by which on the trunk generally, but particularly in the neck and abdomen, it is distinguished. There can be no doubt that the superficial fascia is no more than condensed cellular mem- brane, and its variety of appearance in different regions depends in a great measure upon pecu- liarities in the motions and arrangement of the parts contained in those regions, e.g. wherever the muscles of a part are in very frequent ac- tion, and at the same time the fascia is com- pressed between the integument and the mus- cles, it sutlers condensation ; this is conspicuous in the abdomen, where there is almost incessant muscular action in consequence of the respi- ratory movements, and where the weight of the viscera, thrown forwards in the erect posture, occasions a considerable pressure upon the an- terior and lateral portions of the abdoniii;al parietes. The deposition of adeps to any great extent is unfavourable to the existence of a distinct fascia superficialis, which is thereby, as it were, decomposed, and hence this fascia is not distinct from the subcutaneous cellular tissue in those regions where, either habitually or preternaturally, this substance is largely de- posited. The superficial fascia is identified with the subcutaneous cellular membrane in the cranial regions, a circumstance which seems attributa- ble to the firm adhesion of the aponeurotic ex- pansion of the occipito-frontalis muscle to the subcutaneous tissue, and also the cutaneous insertion of other muscles ; to a similar cause we may ascribe the indistinctness of this fascia in the face also, as likewise to the great depo- sition of fat in some parts of this region. In the pectoral region it is attenuated, and is more intimately connected with the proper cellular covering of the great muscles than with the subcutaneous cellular tissue. Where the superficial fascia has suffered condensation to a considerable extent, and there is a complete absence of adipose sub- stance, it assumes an appearance which has given rise to the designation " fibro-cellular," in consequence of the existence of thick, white, and opaque bundles intersecting the membrane in various directions; these bundles seem to be produced by the close application of the walls of the cells to each other, and the conse- quent obliteration of their cavities. This, how- ever, I believe is the nearest approach that the superficial fascia makes to fibrous membrane ; and I am strongly disposed to question the accuracy of Velpeau's assertion, that it is some- times transformed into the yellow fibrous or into muscular tissue. The elastic abdominal ex- pansion, described by Girard, is certainly not a conversion of the superficial fascia, but of the muscular aponeurosis. Among the cellular fasehe, Velpeau* de- scribes a layer of cellular membrane, pretty uniform in its characters, and in some localities of great practical importance, and gives it the * Anat. Chiiurg. t. i. p. 42. FAT. 231 name fascia supeijicialis interna. It is in contact with the serous membranes of the prin- cipal cavities in the body, with those of the abdomen, thorax, and pelvis in particular; in the former of which it has attracted most atten- tion under the denomination of {he fascia pro- pria. This cellular layer lies between the serous membrane and the fibrous layer which lines the parietes of the cavities, as for instance the fascia transversalis in the abdomen ; and consequently in this last cavity, when any viscus is protruded, carrying a peritoneal sac before it, this cellular layer uniformly forms the immediate investment of the sac, and is there- fore called fascia propria, a hernial covering which every practical surgeon well knows is often of considerable density and thickness, and to which indeed is attributable the so-called thickening of the sac itself. 2. Aponeuroses or aponeurotic fascne. — This appellation should be confined to those textures which are purely fibrous, and belong to either the white fibrous tissue or the yellow. In man, they belong entirely to the former class, but we see some interesting examples among the lower animals, where, while the same characters as to intimate texture are preserved, they assume a yellow colour, and exhibit most manifestly the property of elasticity. J^§^% The greatest numbe/^^fhe fibrous aponeu- roses are connected witliv muscular fibres, and in fact serve as tendons; to {facta,, and are de- scribed as such. Of these we have the best examples in the fibrous aponeuroses of the ab- dominal muscles, by which a considerable por- tion of the paries of this cavity is constructed of a resisting inelastic material, which is at the same time under the control and regulation of muscular fibre. These expansions are com- posed of silvery white parallel fibres, in many places strengthened by bundles which cross and interlace with the fibres last named, e. g. the intercolumnar bands at the apex of the ex- ternal abdominal ring. It is interesting to notice that in the larger quadrupeds, when the weight of the viscera is imposed on these aponeuroses, they are composed of the yellow elastic fibrous tissue. I have also seen the fascia lata thus converted. A second class of these aponeuroses consists of those which cover the soft parts in particular regions. In general we find that where there are many muscles covered, the aponeurosis sends in processes by which each muscle is separately invested, these processes being ulti- mately inserted into the periosteum of the bone. Thus the fascia lata of the thigh separates by means of processes prolonged from its deep surface, the various muscles to which it forms an external envelope, in such a manner that, if the muscles be carefully dissected away from a thigh, without opening the fascia more than is sufficient for their removal, it will appear to form a series of channels in which the muscles are lodged. A similar arrangement is found in the leg and foot, and in each of the segments of the upper extremity. The fascia lata has the peculiarity of being in a great degree influenced in its tension by a muscle, called from that office, tensor vagina J'cmoris, and the fascia which covers the palm of the hand is likewise governed by the palmaris longus, the connec- tion of which, however, with the fascia seems to have reference, not to the functions of the fascia, but to the power of the muscle, in aid of the other flexors of the wrist; the fascia; of the leg and arm too receive the terminal expan- sion of the tendons of muscles. The strength of these aponeurotic sheaths is proportionate to the strength of the muscles they cover; this is apparent, by comparing the fascia; of the arm and of the thigh; the strength of the latter greatly exceeds that of the former, and in the thigh itself the vastus externus muscle is covered by a portion of the fascia lata, much stronger than those which cover the muscles on its posterior and inner aspects. In a third class of aponeuroses are enume- rated simple lamellae of fibrous membrane, which are found for the most part in connexion with the walls of cavities : such are the fascia transversalis, connected with the abdomen ; the fascia iliaca and pelvica, connected with the pelvis ; and the fibrous expansion lining the thorax, which has not received a name. The aponeurotic fasciae are most valuable in their power of resistance, and thus efficacious in maintaining organs in their proper situa- tions ; that they exert a considerable degree of compression upon the muscles is rendered evident by the hernia of the muscular fibres which takes place when an incision is made into the fascia lata of the thigh ; they thus re- gulate the combined action of muscles and render more complete their isolated action. It is incumbent on the surgeon to remember how they confine purulent collections and oppose their progress to the surface, a property which is likewise observable in the cellular fascia?, whose power of resistance is, however, much less, but their elasticity much greater. Such is a brief notice of the generalities con- nected with the fascia? of the body : the situa- tion, connections, and structure of many of them are of great interest to the surgical anato- mist, and will be found fully detailed in the articles devoted to the surgical anatomy of the regions. The subject is also very com- prehensively treated in the following works, God/nan, Anatomical Investigations, Phila- delph. 1824; Vclpeau, Anat. Chirurgicale, t. i. ed. 2de ; Paillard, Description complete des Membranes fibreuses, Par. 1827 ; Cruveil/iier, Anat. Descript. t. ii. Aponeurologie, Par. 1834 ; Bourgert/, Anatomie de l'homme, t. ii. (R. B. Todd. J FAT. (o-TEaj, tti^eAjj, adeps, pinguedo; Fr. graissc; Germ. Fett; Ital. grasso.) Under this term we include a variety of animal pro- ducts which bear a general resemblance to each other, and to a series of corresponding substances in the vegetable kingdom ; the fats of animals being, like the vegetable oils, ternary compounds of carbon, hydrogen, and oxygen, and not, apparently in any instance, containing nitrogen, except as an adventitious or acciden- tal ingredient. 232 FAT. Fat is a deposition in the cellular membrane of certain parts of the body, especially under the skin, in the omentum, in the region of the kidneys, and within the cylindrical bones: it also occurs here and there among the muscles, and sometimes is accumulated to an extent so unnatural as to form a species of disease. In birds it is chiefly seated immediately below the skin, and in water-fowl it is largely secreted by the glands of the rump : in the whale and other warm-blooded inhabitants of the deep, it is chiefly contained in the head and jaw-bones, and abundantly interposed between the skin and the flesh ; in fish it abounds in the liver, as in the shark, cod, and ling, or is distributed over the whole body, as in the pilchard, herring, and sprat. Various opinions have been entertained re- specting the formation of fat, and its insolu- bility in water has led to the idea of its produc- tion in the places in which it occurs; but as it is found in the blood and in some other of the fluids of the body, it is probably partly received with the food, and partly formed by the process of secretion. Its remarkable absorption in cer- tain cases of disease of the chylopoietic viscera, and of deficiency of proper food, seems to point it out as a source of nutriment of which the ani- mal economy may avail itself on emergency ; and accordingly in cases of emaciation or atro- phy, it is the first substance which disappears. It varies in consistency and characters in the diffe- rent tribes of animals, and in the greater num- ber of amphibia and fishes it is usually liquid at ordinary temperatures. (See AdiposeTissue.) The general chemical characters of fat have been long known, as well as its important pro- perty of saponification by means of the alkalis ; but the real nature of the changes which it un- dergoes in this process, and the essential dis- tinctive characters of its varieties, were first satisfactorily investigated by Chevreul,* whose essay upon the subject has been justly cited as a -model of chemical research. It is chiefly from this source, and from the abstract of its contents given by Berzelius,f that we have taken the following details. All the varieties of fat are resolvable into mixtures of stearin and elain, (from cteac^, suet, and cXukiv, oil,) that is, into a solid and liquid ; but there are peculiar differences be- longing to these products in each individual species, which sometimes seem to depend upon very trifling causes, and at others to be con- nected with distinct ultimate composition. There are two modes by which the stearin and elain of fat may be separated: the one consists in subjecting it to pressure, (having previously softened it by heat, if necessary;) and the other, by the action of boiling alcohol, which, on cooling, deposits the stearin, and retains the elain in solution ; the latter separates on the addition of water, still however retaining a little stearin ; they may be ultimately separated by digestion in cold alcohol, sp. gr. .835, which * Kecherches chimiqucs sur les corps gras d'ori- gine animate. Paris, 1823. t Lehrbuch dei Cheroie. B. 3 and 4. Dresden, 1027. takes up the elain, and leaves it after careful distillation ; the stearin remains undissolved. Fat may be separated from its associated cellular texture, by cutting it into small pieces and melting it in boiling water ; it collects upon the surface, and when cold is removed, and again fused in a water-bath, and strained through fine cambric. Many varieties of fat, when dissolved in boiling alcohol and precipi- tated by water, leave a peculiar and slightly acid and saline extract in solution, apparently derived from the enveloping membranes. 1. The softer kinds of fat are termed lard, of which hogs-lard furnishes a good example: it is white, fusible at a temperature between 75° and 85°, and of a specific gravity = about 0.938. When cooled to 32°, and pressed between folds of bibulous paper, it gives out 62 per cent, of colourless elain, which remains fluid at very low temperatures, has a sp. gr. = .915, and is soluble in less than its weight of boiling alco- hol, the solution becoming turbid when cooled to about 140°. The residuary stearin is ino- dorous, hard, and granular: when fused, it remains liquid at the temperature of 100°, but, on congealing, it rises to 130°, and assumes a crystalline appearance. W hen hog's-lard becomes rancid, a pecu- liar volatile acid forms in it, which has not been examined. 100 parts of hog's-lard yield, when saponified, 94.65 margaric and oleic acid, which when fused concrete at 150°; and 9. of glycerine. According fo Chevreul's analysis, the ultimate elements of hog's-lard are — Carbon 79.098 Hydrogen 1 1.146 Oxygen 9.756 100.000 2. Human fat is another species of lard ; but it differs in different parts of the body. The fat from the kidney, when melted, is yellow, inodorous, begins to concrete at 77°, and is solid at about 60°. It requires 40 parts of boiling alcohol of 0.841 for solution, and this deposits stearin as it cools, which, when puri- fied bv pressure between folds of filtering paper at 77°, is colourless, fusible at 122°, and may then be cooled down to 105°, before it concretes ; in the act of concreting its tempera- ture rises to 120°, and it becomes crystalline, and soluble in about four parts of boiling alco- hol, the greater part being deposited in acicular crystals as the solution cools. The elain of human fat, obtained by the action of hot water upon the paper by which it had been absorbed, is colourless, remains fluid at 40°, and con- cretes at a lower temperature. Its specific gravity at 60° is .913 ; it is inodorous, and has a sweetish taste. It is soluble in less than its weight of boiline alcohol, and the solution be- comes turbid when cooled to about 62°. 100 parts of human fat yield, when saponified, about 96 of margaric and oleic acids fusible at about 90°, and from 9 to 10 of glycerin. According to Chevreul, human fat and its elain are composed as follows: — FAT. 233 FAT. Carbon 79.000 Hydrogen 11.416 Oxygen 9.584 100.000 ELAIN. 78 566 11.447 9.987 100.000 3. The Jut of beef when melted begins to concrete at 100°: it requires for solution 40 parts of boiling alcohol, and contains about three-fourths its weight of stearin, which is obtained by stirring the melted fat whilst it is concreting, and then pressing it in woollen cloths at a temperature of about 95", by which the elain is squeezed out, together with a por- tion of stearin, which is deposited at a lower temperature, for the elain does not congeal at 32°. The stearin is white, granularly crystal- line, fusible at 112°, and may be cooled to 100° before it congeals, when its temperature rises to 112°. It looks and burns like wax. 100 parts of alcohol dissolve 15 of this stearin : when saponified, it yields 0.95 of fat acids, which fuse at 130°. The elain of beef fat is colour- less and almost inodorous, and soluble in less than its weight of boiling alcohol. Candles made of the stearin of this fat, with a small addition of wax to destroy its brittle and crys- talline texture, are little inferior to wax candles. 4. Neat's foot oil is obtained by boiling the lower ends of the shin-bones of the ox, after the removal of the hair and hoofs, in water. This oil remains fluid below"32°, and after the sepa- ration of the stearin, is used for greasing turret- clocks, which are often so exposed to cold as to freeze other oils. 5. Gout's fat is characterized by its peculiar colour, which seems to depend upon the pre- sence of a distinct fatty matter, which, in the separation of the stearin and elain, is asso- ciated with the latter, and which Chevreul has called hircin. When the elain is saponified, a liquid volatile acid is formed, which may be separated as follows : four parts of the fat are made into soap with one of hydrate of potassa dissolved in four of water : the soap is after- wards diluted, and decomposed by phosphoric or tartaric acid, by which the fat acids are sepa- rated : these are distilled with water, taking care that the contents of the retort do not boil over: the distilled liquid is saturated with hydjate of baryta, evaporated to dryness, and decomposed by distillation with sulphuric acid diluted with its weight of water : the acid is separated in the form of a colourless volatile oil which floats upon the distilled liquid ; Chevreul terms it hircic acid: it congeals at 32°: it has the odour of the goat, blended with that of acetic acid ; it reddens litmus, dissolves difficultly in water, and readily in alcohol : it forms distinct salts with the bases : the salt of ammonia has a strong hircine odour : that of potassa is deliquescent, and that of baryta difficultly soluble in water. 6. Mutton fat is whiter than that of beef, and acquires a peculiar odour by exposure to air; when melted it begins to concrete at about 100°. It requires 44 parts of boiling alcohol for solution. Its stearin, when fused, begins to congeal at 100°, and its temperature rises on solidification to 113°. 100 parts of alcohol dissolve 16 of it. Its elain is colourless, slightly odorous, sp. gr. 0.913, and 80 parts of it are soluble in 100 of boiling alcohol. When saponified, it yields a very small quantity of hircic acid. This species of fat, together with its stearin and elain, are composed as fol- lows : — FAT. STEARIN. ELAIN. Carbon 78.996 78.776 79.354 Hydrogen ..11.700 11.770 11.090 Oxygen 9.304 9.454 9.556 100.000 100.000 100000 7. Whale oil, or train oil, (from whale blub- ber,) sp. gr. .927, when cooled to 32°, deposits stearin ; the filtered oil is then soluble in 0.82 of boiling alcohol. Aided by heat it dissolves arsenious acid, oxide of copper, and oxide of lead ; sulphuric and muriatic acids render the latter combination turbid, nitric acid tinges it dark brown with effervescence; and it is coa- gulated by potassa and soda. This oil is easily saponified when mixed with 0.6 its weight of hydrated potassa, and five parts of water ; the soap is brown, soluble in water, and when de- composed by tartaric acid and the sour liquid distilled, it yields traces of phoeenic acid, also glycerine, and oleic and margarir, but no stearic acid : these acids are accompanied by a greasy substance which has the odour of the oil. The stearic portion of train oil, when freed from adhering elain by washing with weak alcohol, concretes, after having been fused, at a temperature between 70° and 80°; it is soluble in 1.8 parts of boiling alcohol, and is deposited in crystals as it cools, leaving a dark thick mother-liquor. When saponified, 100 parts yield 85 of margaric and oleic acids, 4 of a brown substance infusible at 212°, and per- fectly soluble in boiling alcohol, 7 of bitterish glycerine, and traces of phoeenic acid. 8. Spermaceti oil, the produce of the sper- maceti whale,* is lodged in the cartilaginous cells of a bony cavity on the upper part of the head ; as it cools, it deposits its peculiar stearic portion in the form of spermaceti; this sub- stance is further separated by pressure in wool- len bags from the oil, and is then washed with a weak solution of caustic potassa, melted in boiling water, and strained; it is commonly cast into oblong blocks, and if the interior liquid portion is drawn off when the exterior has concreted, the cavity exhibits upon its sur- faces a beautiful crystalline texture. Sperma- ceti, as it occurs in commerce, is in semi-trans- parent brittle masses of a foliated fracture, and soapy to the touch ; it has a slight odour and a greasy taste, and when long kept becomes yel- lowish and rancid. Its specific gravity is .943; it fuses at about 114°. 100 parts of boiling' alcohol, sp.gr. .823, dissolve 3.5 spermaceti, and about 0.9 is deposited on cooling. Warm ether dissolves it so copiously, that the solution conc-etes on cooling; by the aid of heat, it * Physetcr macrocephalus, or Cachalot. 234 FAT. dissolves in the fat and volatile oils, and is in part deposited as the solution cools. Alcohol always extracts a small portion of oil from the spermaceti of commerce; as the boiling alco- holic solution cools, it deposits the purified spermaceti in white crystalline scales, and in this state, Chevreul terms it cetine. Cetine does not fuse under 120°; it forms, on cooling, a lamellar, shining, inodorous, and insipid mass, which is volatile at high temperatures, and may be distilled without decomposition. It burns with a brilliant white flame, and dis- solves in about four parts of absolute alcohol ; it is very difficultly saponified; digested for several days at a temperature between 120° and 190°, with its weight of caustic potassa and two parts of water, it yields inargarate and oleate of potassa, and a peculiar fatty matter, which Chevreul calls ethal,* and which amounts to about 40 per cc7it. of the cetine used. To ob- tain it in an insulated state the results of the saponification of cetine are decomposed by tartaric acid, which separates the margaric and oleic acid, together with the ethal ; the fat acids are saturated with hydrate of baryta, and the resulting mixture well washed with water to separate all excess of base; it is then well dried, and digested in cold alcohol or ether, which takes up the ethal and leaves the barvtic salts ; the former is then obtained by evapora- tion of the solvent. Ethal is a solid, transpa- rent, crystalline, fatty matter, without smell or taste; when melted alone it congeals at 120° into a crystalline cake ; it is so volatile that it passes over in vapour when distilled with yvater. It burns like yvax, and is soluble in all propor- tions in pure alcohol at a temperature below 140°. It readily unites by fusion with fat and the fat acids, and yvhen pure is not acted upon by a solution of caustic potassa; but if mixed with a little soap it then forms a flexible yel- lowish compound, fusible at about 145°, and yielding an emulsive hydrate with boiling water. The ultimate composition of train oil, sper- maceti oil, spermaceti, cetine, and ethal, are shewn in the following tables : — TRAIN OIL. SPERMACETI OIL. ( 'ai bon . . Hydrogen Oxygen. . Board. . 76.1 . 12.4 .11.5 100.0 Carbon . . . Hydrogen. Oxygen ... SPERMACETI. Berard. ... 79.5 11.6 8.9 Ure. 79.0 10.5 10.5 100.0 < F. IT N E. Chevreul. 81.6(50 12.862 5.478 100.0 100.000 * From the first syllables of tin- words vlher ami alcohol t in Consequence of a resemblance in ultimate composition to those liquids. Carbon . . 17 Hydrogen 18 Oxygen. . 1 ethal. (Chevreul.) Atoms. £fnjra<«n(>. Theory. Erpertmnt. 102 79.69 79.766 18 14.06 13.945 8 6.25 6.289 128 100.00 100.000 9. Phoccnine is a peculiar fatty substance contained in the oil of certain species of por- poise ( Delphinus phocena and globiceps). When this oil is saponified, it yields margaric and oleic acid and cetine, and a peculiar vola- tile acid obtained by a process similar to that for separating hircic acid, and which has been termed phocenic acid.* It is a thin, colourless, strong-smelling oil, of a peculiar acrid, acid, and aromatic taste; its specific gravity is .932 ; it does not congeal yvhen cooled doyvn to 14°. Its boiling point is above 212°. In this state it is an hydrate, containing 9 per cent, of water, from which it has not been freed. It is solu- ble in all proportions in pure alcohol. The neutral salts of this acid ( plwecnatesj are inodorous, but any free acid, even the car- bonic, in a gentle heat, evolves the odour of the phocenic acid. Heated in the air they exhale an aromatic odour, dependent upon the forma- tion of a peculiar product. By dry distillation they blacken, evolve olefiant gas and carbonic acid, and a thin, odorous, yellow oil, insoluble in potassa. The pliocenates of potassa, soda, and ammonia, are deliquescent ; the phocenate of baryta forms efflorescent prismatic crystals ; and that of lime, small acicular prisms. The neutral phocenate of lead, evaporated in vacuo, yields flexible lamellar crystals, which are fusible and easily become basic when heated ; the subphocenate of lead is difficultly soluble and crystallisable, and decomposed by the car- bonic acid of the air. According to Chevreul, the anhydrous pho- cenic acid (as existing in its anhydrous salts) consists of Atoms. Equivalents, Theory. Experiment. Carbon . . 10 60 65.93 65.00 Hydrogen 7 7 7.69 8 25 Oxygen . . 3 24 26.38 26.75 1 91 100.00 100.00 And the oily hydrated acid is a compound of 1 atom of dry acid and 1 atom of yvater, or 91 + 9 = 100. 10. The Jut of birds has been but little exa- mined ; Chevreul states that the fat of gee* concretes after fusion at about 80° into a gra- nular mass of the consistency of butter. Ac- cording to llraconnot it yields by pressure at 32°, 0.68 of yellowish elain, having the odour and taste peculiar to this kind of fat, and 0.32 of stearin, fusible at 1 10°, and soluble in rather more than three parts of anhydrous alcohol. When saponified, it yields margaric and oleic acid and glycerine. • The same acid is contained, according to Chevreul, in the ripe berries of the Viburnum ojiutut. FEMORAL ARTERY. 235 The fat of the duck and the turkey nearly esembles the above. 11. Among insects, peculiar kinds of fat iave been obtained from ants, and from the ochini nl insect. The latter has been examined >y Pelletier and Caventou. (Ann. de Ch. et 'hys. viii. 271.) It is obtained by digesting iruised cochineal in ether, evaporating and re- issolving the residue in alcohol, till it remains ipon evaporation in the form of colourless iearly scales, insipid and inodorous, and fusible t 104°. 12. Under the term adipocere, we have else- where described a species of fatty matter which ppears to result from the slow decomposition f fi brine ; and in some diseased states of the iody, a large proportion of the flesh occasion- lly puts on the appearance of fat. In the i>rmer case, it has been supposed that the pro- luct is the fat originally existing in the body, which, during the putrefaction of the other larts, has become acidified, that is, converted nto margaric, stearic, and oleic acids ; and bat these acids are more or less saturated by lie ammonia which is at the same time gene- [Ued, and by small quantities of lime and nagnesia resulting from the decomposition of ertain salts of those earths pre-existing in the nimal matter. This view of the nature of adi- locere appears so far correct ; but the quantity >f the altered fatty matter which was found in he cases alluded to, and in others where heaps •I refuse flesh have been exposed to humid pu- refaction, is sometimes such as to render it lighly probable that a portion of the fatty natter is an actual product of the decay, and ot merely an educt or residue. In regard to the apparent morbid conver- ion of muscle into fat in the living body, Jerzelius observes that, because the muscles iecome white, it has been assumed that they re actually converted into fat, but that the ppearance depends solely upon the absence f red blood, for the muscles under such ircumstances do not lose their power of mo- ion. The truth is that, in these cases, the ccumulation of fat goes on to such an extent i the interstitial cellular membrane of the ruscular fibre, as gradually to occasion its lmost entire absorption, and such of the mus- ics as undergo this change gradually lose leir contractile powers. Two mutton-chops, fhich have undergone this change, and in .Inch the altered muscle and the ordinary ex- jrnal layer of adipose membrane are quite dis- nct, are preserved in the Museum of the "ollege of Surgeons, and there is a printed amphlet giving an account of the symptoms nder which the sheep laboured. What may e the chemical peculiarities of the fat depo- ited among the fibres, as compared with the rdinary fat, has not been ascertained. The above is an enumeration of such of the arieties of animal fat as have been chemically xamined. In their general characters they losely resemble the corresponding compounds f the vegetable kingdom ; and, with the exeep- ons specified, the process of saponification Fects upon them very similar changes : thev are also similarly acted on by the acids. Some of them seem to afford distinct products when subjected to destructive distillation, and during the decomposition of whale oil for the produc- tion of carburetted hydrogen for the purposes of gas illumination, a variety of binary com- pounds of hydrogen and carbon, with some other products, are obtained, the nature of which has been ably investigated by Professor Faraday. • ( W. T. Brande.) FEMORAL ARTERY (arteria cruralis; Germ, die Schenkelarterie ). The femoral ar- tery is the main channel through which the lower extremity is supplied with blood : in an extended sense it might, with propriety, be understood to comprehend so much of the artery of the extremity as is contained within the thigh, intermediate to those of the abdo- men and the leg; but the variety in the situ- ation and relations of that vessel in different stages of its course is so great that it has been distinguished into two, the proper femoral and the popliteal ; the former appellation being applied to so much of the vessel as is situate in the superior part of the limb, and the latter to that portion which is contained in the lower, in the popliteal region. The comparative ex- tent of the two divisions of the artery differs considerably, the femoral predominating much in this respect, and occupying two-thirds of the thigh, while the popliteal occupies but one; hence the particular extent of each may be exactly defined by dividing the thigh, longi- tudinally, into three equal parts, of which the two superior will appertain to the former, and the inferior to the latter. The proper femoral artery, then, engages the two superior thirds of the main artery of the thigh, continued from the external iliac artery above, and into the popliteal below. It emerges from beneath Poupart's ligament into the thigh, external to the femoral vein, and on the outside of the ilio-pectineal eminence of the os innominatum, and it passes into the popliteal region below through an aperture cir- cumscribed by the tendons of the adductor niagnus and vastus internus muscles. Its course is oblique from above downward, and from before backward, corresponding to a line reaching from a point midway between the anterior superior spinous process of the ilium, and the symphysis pubis upon the front of the limb above, to another midway between the two condyles of the femur, on the posterior aspect of the bone below. Its mean direction is straight, or nearly so, corresponding to the line which has been mentioned, or, according to Harrison,-)- to a line drawn from the centre of Poupart's ligament to the inner edge of the patella; but its course is, for the most part, more or less serpentine, the vessel forming as it descends curvatures directed inward and outward. The presence and degree of these curvatures, however, are influenced very much * Phil. Trans. 1825. t Surcic.il Anatomv of the Arteries, vol. ii. p. 137. 236 FEMORAL ARTERY. by the state of the vessel and by the position of the limb; when the artery is empty, they are less marked than when it is full ; and when the limb is extended, they are removed; when flexed, they are reproduced ; while in some subjects again, they appear to be absent, the line of the vessel's course being almost direct. The degree to which the artery passes back- ward is not equally great at all parts of its course: in its upper half, i.e. from Poupart's ligament until it lies upon the adductor longus muscle, the vessel inclines much more back- ward than in the remainder, and at the same time describes a curve concave forward, but both the latter particulars are more remarkable when the thigh is flexed, and in thin subjects, than when the limb is extended and in sub- jects which are in good condition ; in the last case the vessel is supported and held forward by the deep fat of the groin situate behind it. In its lower half the artery inclines less back- ward, being supported by the muscles against which it rests. The femoral artery is also described as in- clining inward * during its descent ; but this statement requires coirection, or at least ex- planation. The vessel certainly does incline inward at some parts of its course, and for the most part it does so as it descends from the os innominatum into the inguinal space, form- ing thereby the curvatures which have been mentioned ; but the general direction of it is either slightly outward, or at the most directly downward, not inward : the opinion that it is inward has arisen, it is to be supposed, from a partial view of its course, which, in conse- quence of its serpentine direction, is likely to mislead, and is at variance with that of the popliteal artery, (the lower part of the same vessel,) which is decidedly outward. In order to be assured of the true direction of the vessel, the writer has tested it carefully by means of the plumb-line, and he has always found that it inclined somewhat outward from the perpendicular : the degree, however, to which the proper femoral artery does so, is not considerable, though sufficient to place the matter beyond doubt. It is to be borne in mind that, in determin- ing the direction of the vessel's course, the limb must be placed in the bearing which it holds naturally in the erect posture, inasmuch as an inclination to either side will influence materially the direction of the artery : thus an inclination of the limb inward will at once give it the same tendency, and render it spiral, both which conditions are removed by placing the limb in its ordinary position. In consequence of the course which the vessel pursues, and of the oblique position of the femur conjointly, the femoral and popliteal arteries hold very different relations to the shaft of that bone ; the former, in the first stage of its course, being in a plane anterior to the femur, and in the middle of the limb being upon its inside; while the latter is situate be- hind the bone, and at the inferior part of the * Uoycr, Clo(]ucl, Harrison. popliteal region corresponds to the axis of its shaft: hence the artery is said* to pass some- what in a spiral manner in reference to the thigh bone ; but this is incorrect, the spiral course being only apparent and resulting from the combined effect of the obliquity of the artery itself backward and outward, and of the shaft of the femur inward and forward : that this is so may be satisfactorily shewn by the application of the plumb-line to the course of the artery, upon the different aspects of the limb; from which it will appear that, allow- ance being made for the serpentine deviations already adverted to, the general course of the vessel is, quum proximi, straight, and that it cannot, at all with propriety, be said to be spiral, this being not a real but an apparent direction, the result of the circumstances which have been mentioned. The point at which the femoral artery com- mences is referred by most writers to Poupart's ligament; this method of demarcation is at- tended with the inconvenience, that during life the exact situation of the ligament is difficult to determine, inasmuch as it does not run direct from one attachment to the other, and that in dissection its position is immediately altered on the division of its connections with the adjoining fascia-: hence the student, not having a fixed point of reference, is often at a loss to distinguish between the iliac and femo- ral arteries, and mistakes affecting the relations of the most important branches of those vessels are liable to be made. For those reasons it appears to me that it would be much pre- ferable to select some fixed and unchanging point to which to refer the commencement of the artery ; and for this purpose I would suggest the ilio-pectineal eminence of the os innominatum, which, to the student at least, if not to the practical surgeon, will afford an unerring guide to the distinction of the one vessel from the other; the femoral artery, at its entrance into the thigh, being situate im- mediately external to the inferior part of that prominence,t with which point the middle of the line connecting the anterior superior spi- nous process of the ilium and the symphysis of the pubis will also be found to correspond. The precise situation of the vessel is referred by some to the centre of Poupart's ligament, or a point midway between the anterior supe- rior spinous process of the ilium and the spinous process of the pubes ; by others to a point midway between the spinous process of the ilium and the symphysis of the pubes. With regard to this question it is to be ob- served that the relation of the artery to the points between which it is situate is not strictly the same in all instances ; that in some it will be found to correspond to the former, and in others to the latter account; but that the latter relation appears to prevail in so much the greater number, that it ought to be adopted as the rule. According to Velpeau it is distant two inches and a quarter from the spinous pro- * Harrison, op. cit. p. 137. t This point will be discussed again. FEMORAL ARTERY. cess of the pubes, and from two and a half to two and three quarters from the superior an- terior spinous process of the ilium. The femoral artery is attended through its entire course by the femoral vein, the two vessels lying in apposition and inclosed within a fibro-cellular investment, to which the ap- pellation femoral sheath will be applied. It is also related to the crural nerve or its branches, and it is contained, together with the vein, in a canal of fascia, which will be denominated the ft moral canal. It is necessary to dwell here, for a little, upon the distinction between the two appel- lations femoral canal and femoral sheath, that a confusion of the one with the other may not arise. The vessels have in fact, throughout their course, two distinct sheaths, which may be considered peculiar to them, contained the one within the other : the external is formed by the fascia lata in a manner to be presently explained, and is in all respects analogous to the canal furnished by the cervical fascia to the carotid artery and jugular vein. This outer sheath, which many may regard as the sheath of the vessels, extends from Poupart's liga- ment to the aperture by which they escape into the popliteal region, and will, for reasons which will appear more fully by-and-bye, be here called the femoral canal. The second or internal sheath is situate within the former, is of variable thickness, according to the point at which it may be examined, being for the most part very thin; adheres in general closely to the vessels, in which particular it differs from the outer one, within which they are com- paratively free ; and not only covers, but also separates them by a thin internal process, which by its density and intimate adhesion to the vessels connects them straitly to each other; it is further not confined, as the other is, to the vessels, while called femoral, but is prolonged upon them into the popliteal region, where in like manner it invests and connects them : to this investment the denomination femoral sheath will be applied. A distinction between the two structures is necessary in a description of the relations of the femoral artery, were it only to mark their existence, but that which I have adopted is rendered imperative by the use already made of the latter appellation with reference to the anatomy of hernia, in the history of which it is ap- plied not to the canal as formed by the fascia lata, but to that, through which the femoral vessels escape from the abdomen, and as formed by the fascia? transversalis and iliaca; and the prolongation of the former of these two fasciae being, in my opinion, con- tinued into the internal and immediate in- vestment of the vessels, it has appeared to me justifiable to extend the signification of the title femoral sheath, and to apply it to that investment throughout their entire course, as well below as above the saphenic opening of the fascia lata; while his application of the former appellation, femoral canal, is sanc- tioned by Cloquet, by whom it is used in the same sense. Beside those which have been already mentioned, the femoral artery has also, during its course, the following general re- lations : — posteriorly it corresponds in suc- cession to the psoas magnus, the pectinalis, the adductor brevis, adductor longus and ad- ductor magnus muscles; anteriorly it is, in the first part of its course, not covered by any muscle and is comparatively superficial ; and through the remainder and more exten- sive portion it is covered by the sartorius. Externally it corresponds to the psoas and iliacus, to the sartorius, the rectus, and lastly to the vastus internus muscles ; the latter of which is interposed between it and the inside of the femur: internally it corresponds to the pectinalis and the adductor longus mus- cles ; and lastly it is overlapped by the sar- torius. It is contained, through its upper half, in the inguinal region. This region is of a triangular prismatic form, the base of the triangle represented by it being above formed by Poupart's ligament, or by a line connecting the anterior superior spinous process of the ilium and the symphysis pubis; its apex below by the meeting of the sartorius and the adductor longus muscles. The sides of the prism are external and internal, inclined, the former backward and inward, the latter backward and outward, and meeting each other along the internal and posterior side of the femur; they are formed, the external by the iliacus and psoas, the rectus, the vastus internus and the sartorius muscles, and the internal by the pectinalis and the adductors. The base of the prism is in front, consisting of the coverings of the space. During its descent from the os innominatum into the inguinal region, the artery generally inclines inward, describing a curve convex out- ward ; and hence, as it seems to me, the entire course of the vessel has been assumed to be inward ; but this first curve, when present, is soon compensated by another in the opposite direction. In its lower half the artery is enclosed between muscles, the vastus internus upon its outside, the adductors longus and magnus behind it, and the sartorius in front. The course of the femoral artery may be advantageously divided into three parts or stages, to be distinguished as first, second, and third, or as superior, middle, and inferior thirds ; in each of which will be found such peculiarities in the relations of the vessel as will justify the number of subdivisions. They may be defined with sufficient precision by dividing the two superior thirds of the thigh into three equal parts, and they will occupy each, according to the stature, from three to five inches. The superior stage reaches from Poupart's ligament to the point at which the artery is first covered by the sartorius : during this its upper third, the vessel is not covered by muscle, except at its termination, where it is overlapped by the inner margin of the sartorius : it is therefore comparatively super- 238 FEMORAL ARTERY. ficial, and its pulsations can be felt during life with greater or less facility according to circumstances, to be explained. It has, how- ever, four structures interposed between it and the surface, and forming its coverings ; viz. the skin, the subcutaneous cellulai stratum, the anterior wall of the femoral canal, and the prolongation of the fascia transversalis or the femoral sheath. The subcutaneous cellular structure pre- sents a remarkable difference according to the condition of the subject or certain other cir- cumstances. When the body is devoid of fat or emaciated, this structure appears a thin, condensed, dry and lamelliform stratum, con- tinued from the abdomen downward upon the lower extremity, and generally denominated the superficial fascia of' the thigh; but when, on the contrary, the body is in good condition, and the quantity of superficial adeps is con- siderable, the appearance of a membranous expansion is removed, and in its stead a thick and uniform stratum of fat is found in- terposed between the skin and the fascia lata. In other cases presenting a medium condition, the stratum of fat and the membranous expan- sion may be both observed : in such case the former is generally superficial, and the latter underneath; but when the accumulation of adeps in the subcutaneous structure is more considerable, e. g. in the healthy infant or in many adults, particularly among females, no trace of superficial fascia is to be found. So much for the varieties which the subcutaneous cellular structure presents naturally. It is also found frequently in abnormal conditions deserving of attention : at times it is divisible to a greater or less extent into a succession of expansions, having each the appearances of fasciae and being of indeterminate number : this disposition, which occurs not unfrequently, and is of considerable importance in a practical point of view, appears due to the influence of pressure exerted by tumours, e. g. that of hernia. Again, in anasarca the subcutaneous structure becomes greatly increased in depth, and loses all appearance of membrane, seeming then a deep gelatinous stratum, consisting of the cellular structure and the effused serum. The depth, therefore, of the femoral artery from the surface, and the number of coverings which it may have in individual cases, must be materially influenced by those several con- ditions of the subcutaneous cellular structure when present, and they should never be lost sight of; else uncertainty and embarrassment must arise in the conduct of operations. It is further to be borne in mind that the account of the coverings of the artery given in this description has reference to the natural and most simple arrangement of those structures. The subcutaneous structure also encloses within it the superficial vessels, nerves, and glands, the relation of some of which to the artery requires notice. The superficial vessels are the saphena vein, the superficial femoral veins, and those veins and arteries by which the inguinal glands are supplied. The saphena vein ascends, from the inner and back part of the knee, along the inner and an- terior aspects of the thigh to its upper extre- mity, where it joins the femoral vein upon its anterior and internal side, at the distance of from one inch to an inch and a half below Poupart's ligament. During its ascent the vein passes forward and outward, and is situate internal to the femoral artery : at the lower extremity of the middle third of the thigh, (the point at which the artery is about to pass into the ham,) it is placed superficial to the vessel, between it and the internal surface of the limb, near to the inner, or at this part the posterior margin of the sartorius muscle ; but as the vein ascends, the distance between the vessels increases, partly because of the greater width of the thigh at its upper part, and partly because the course of the vein describes a curve convex inward ; and at the termination of the latter it amounts to the width of the femoral vein or somewrhat more ; lower down it is still greater in consequence of the curve formed by the saphena. Hence, in operations upon the superior part of the artery, the saphena ought to be exempt from danger ; while at the lower part it must be very much exposed, if the inner margin of the sartorius be cut upon as the guide to the vessel. The superficial femoral veins next claim attention : they are very irregular in their course and destination, and therefore are the moie likely to prove a source of embarrass- ment in operation. They are smaller than the saphena, but yet are in many cases of con- siderable size : they present, according to the subject, two dispositions; either they join the saphena during its ascent at variable points in the course of the thigh, and in such case cross the limb and the artery obliquely from without inward, at different heights ; or they form one or two considerable vessels, which ascend external to the saphena, and open into the femoral vein hi front, at the same time with the former vessel, passing through the superficial lamina of the fascia lata in the same manner as it does. When there are two such veins, the inner one is generally situate internal to the artery, between it and the saphena, and consequently very near to it ; while the external one, or the vein, if there be but one, runs upward and inward, and crosses the artery in its upper thi.d, between the point at which the saphena joins the femoral vein and that at which the artery is overlapped by the sartorius : the last-de- scribed vein, when present, must obviously be much endangered i:i exposing the femoral artery at this part of its course, and perhaps is the vessel which has given rise to the idea that the saphena itself may be encountered in cutting upon the artery in this situation. The superficial inguinal glands are distin- guished into two sets, a superior and an in- ferior: those of the former are more numerous, and nearer to the integuments than the latter. They are ranged immediately below l'oupart's ligament, having their longer diameter parallel to it, and in greatest number superficial to that part of the iliac portion of the fascia lata, FEMOKAI- ARTERY. 239 which is called its cribriform portion, and over the course of the femoral artery, across which they are placed obliquely : they are separated from the vessel hy the superficial lamina of the iliac portion of the fascia, and by the prolongation of the fascia transversal is, with the interposed cellular structure; and they derive numerous arterial and venous branches from the main trunks bene ath : those branches, which are given off partly by the vessels themselves, and partly by their super- ficial pudic, superficial epigastric, and su- perficial anterior iliac branches, pass through the interposed structures in order to reach the glands; in doing so they carry with them sheaths from the fascia lata, which is prolonged upon each as it < scapes, and thus they become the means of establishing that connection be- tween the fascia in the groin and die subcu- taneous stratum, in which the glands are enveloped, which is considered to influence so remarkably the course of femoral hernia. The glands of the second set are less nu- merous, are situate farther from Poupart's ligament than the former, being below the entrance of the saphena ; they are also deeper seated, lying upon the fascia lata, and they are placed with their longer diameter parallel, or nearly so, to the femur and to the course of the artery. Their relation to the artery is not in all cases the same, inasmuch as the disposition of neither part is strictly uniform, hut usually one or two of them lie over the vessel, or immediately on either side of its course; their relation to it, however, is, in the natural condition of the parts, not of great consequence; for in such case they may be easily held aside during operation if necessary, and thus both they and their lymphatic vessels be saved from injury. The relation of the inguinal glands, more particularly the superior, to the femoral artery suggests several inferences. 1st, That the very commencement of the artery's course, although the situation in which the vessel is nearest to the surface, and that in which it can be most easily distinguished by its pulsa- tion, is yet not the most eligible part at which to expose it, since the glands and their vessels cannot, by any precaution of the surgeon, be protected certainly from injury. 2dly, That phagedenic ulceration of the glands of the groin must be attended with great danger from the vicinity of the great vessels. 3dly, That hemorrhage consequent upon such ulceration does not necessarily proceed from those vessels themselves; but that it may, and in the ma- jority of cases in the first instance probably does arise from the branches supplying the glands ; and, 4th, That the groin is likely to be the seat of pulsating tumours requiring to be distinguished from aneurism. The third covering of the artery is the superficial lamina of the iliac portion of the fascia lata. This portion having covered the an- terior surface of the iliacus and psoas muscles as far as the middle of Poupart's ligament, along which it is attached from without inward, divides at that point into two laminae, a deep one and a superficial one; the former passes inward and backward from the ligament, upon the psoas muscle, to the ilio-pectineal eminence of the os innominatum, into which it is in- serted, continued thence upward, upon the inside of the muscle, along the brim of the pelvis into the fascia iliaca, and downward across the capsule of the ilio-femoral articula- tion, to which it is also attached : it is in fact that part of the fascia iliaca, (for the fascia iliaca and the iliac portion of the fascia lata are one and the same expansion, distinguished from each other only by Poupart's ligament,) which is situate upon the inside of the psoas magnus, and which forms the outer wall of the femoral canal, being interposed between the femoral artery and the muscle. At the iho- pectineal eminence it also meets and is iden- tified with the pubic portion of the fascia lata, which is attached to the pectineal line of the pubis, in continuation with this deep lamina of the iliac portion, covers the pectinalis muscle, and is situated immediately behind the vessels. When that part of the deep lamina of the iliac portion of the fascia lata which extends from Poupart's ligament to the ilio-pectineal eminence has had the prolonga- tion of the fascia downward detached from it, it appears as an oblique partition dividing the crural arch into two parts, an external containing the iliacus and psoas muscles with the crural nerve, and an internal containing the femoral vessels. The second lamina of the iliac portion of the fascia lata— the superficial one — passes inward across the femoral vessels, superficial to them and to the prolongation of the fascia transversalis, until it has reached the inside of the vessels : it is at the same time attached above, in front of the vessels, and in con- tinuation with the iliac portion itself, to the inferior margin of Poupart's ligament, from its middle to the base of its third insertion — Gimbernat's ligament, and upon their inside along the base of the latter ligament as far as the pectineal line of the pubis, into which it is finally inserted, external to the base of Gimbemat, between it and the insertion of the fascia transversalis upon the inside of the aperture of the femoral sheath, and where it is also identified with the pubic portion of the fascia attached along the same line : from thence it is united to the anterior surface of the pubic portion of the fascia lata, down- ward along the inside of the vessels. The superficial lamina of the iliac portion is thus thrown across the front of the vessels, and by the disposition, which has been detailed, the fascia lata encloses the vessels between the two laminae, and forms, by means of them and their connection at either side, a canal, within which are contained the vessels and the prolongation of the fascia transversalis covering them in front. The constitution of the canal, as described, may be considered to extend from Poupart's ligament until the artery is about to be covered by the sartorius; from whence its anterior wall is formed, through the remainder of the vessel's course, by another 240 FEMORAL ARTERY. anil deeper layer of the fascia. The canal thus formed, to which the author would apply, with Cloquet, the term femoral canal, is widest at its upper extremity, i. e. at Poupart's ligament ; from whence, as it descends, it contracts in width until it has passed the entrance of the saphena, beyond which it continues of nearly uniform capacity to its termination. The diminution in the transverse extent of the canal is due to the direction of the line of union between the superficial lamina of the iliac portion and the pubic portion of the fascia, which, as has been already stated, inclines outward as it descends from the pectineal line of the pubis to the point at which the saphena joins the femoral vein. In the interval between Poupart's ligament and the junction of the two veins the superficial lamina is thinner, less aponeu- rotic, and more of a cellular character than other parts of the fascia ; but it is subject to much variety in this respect : in all cases it is thinner and weaker internally than externally, but in some it is throughout distinct and un- broken, unless by the passage of vessels, and presents aponeurotic characters as decidedly as many other parts of the expansion ; while in others it is cellular, indistinct, and even fatty, not easily distinguishable from the subcuta- neous structure, and so thin as to seem de- ficient toward its inner part, or to have its line of union with the pubic portion inter- rupted at one or more points. The extent and connections of this portion of the fascia will be most satisfactorily displayed by first detaching Poupart's ligament, upon its abdo- minal side, from the fascia transversalis as it descends beneath the ligament, and then care- fully insinuating the handle of a knife down- ward beneath the ligament and the superficial lamina of the iliac portion of the fascia lata, between them and the prolongation of the fascia transversalis : this done, the superficial lamina may, with the guidance of the instru- ment beneath it, be satisfactorily traced. The fourth structure, by which the femoral artery is covered in the first stage of its course, is the prolongation of the fascia transversalis. The two abdominal fascia?, the transversalis and the iliaca, which are, at every other part of the crural arch, either identified and united, or inserted into bone, are separated in the in- terval between the middle of Poupart's and the base of Gimbernat's ligament, and de- scend into the thigh, the former in front of or superficial to the femoral vessels, beneath Pou- part's ligament and the superficial lamina of the iliac portion of the fascia lata ; the latter behind or deeper than the vessels, between them and the psoas and pectinalis muscles, constituting or continued into the pubic or deep portion of the fascia lata. The two fascia; thus leave an aperture beneath Poupart's liga- ment, through which the vessels escape from the abdomen, and at the same time inclose them between them ; the prolongation of the transversalis covering them in front, the iliac and pubic portion of the fascia lata situate behind them. As it descends upon the vessels, the prolongation from the transversalis is united to the fascia iliaca and iliac portion of the fascia lata upon their outside ; and to the pubic portion upon their inside, in the same manner as the superficial lamina of the iliac portion, and within it in reference to the femoral canal : it may therefore be viewed in one of two lights with regard to that canal, viz. either as de- scending into it superficial to the vessels, and entering into the constitution of its anterior wall, or as concurring with the other fasciae to form, beneath the superficial lamina of the iliac portion of the fascia lata, a sheath, in which the vessels are immediately contained. The latter is the view which has been adopted by anatomists, and the appellation femoral has been given to the sheath so formed. Like the superficial lamina of the iliac portion of the fascia lata, the prolongation of the fascia trans- versalis is wider at Poupart's ligament, and diminishes in w idth as it descends to the junc- tion of the saphena and femoral veins : hence the femoral sheath is considerably larger supe- riorly than inferiorly, does not embrace the vessels closely at their entrance into the thigh, and but for the aponeurotic expansion described by Colles, and termed by Cloquet the crural septum, would be open toward the abdomen ; but in proportion as they descend, it invests them more closely until it reaches the entrance of the saphena, at which point its connection to them is intimate, and from whence the prolon- gation seems to the author to be continued down- ward into the dense thin cellular or fibro-cellular investment, by which the artery and vein are surrounded and connected together within the femoral canal during the remainder of their course through the thigh. From Sir A. Coo- per's account of the prolongation it would appear that it terminated, or cannot be traced further than two inches below Poupart's liga- ment. Sir Astley says, " these vessels pass down within the sheath for about two inches, after which they carry with them a closely investing fascia derived from the fascia lata." By the " closely investing fascia," the author understands the proper sheath of the vessels, which has been adverted to, and with which the prolongation of the fascia transversalis appears to him to be identified. According to Professor Harrison,* " it soon becomes thin and indistinct, and is lost in the cribriform part of the fascia lata;" but in this view of its termination the author cannot concur ; the pro- longation is doubtless connected to the cribri- form fascia (the superficial lamina of the iliac portion of the fascia lata) by the vessels, which traverse both structures, but it is notwith- standing separable, without much difficulty, from it, by means of the proceeding already recommended for the display of that part — a proceeding equally applicable to that of the distinct existence and the connections of the expansion in question ; the superficial lamina being at the same time, as directed by Colles, divided from above downward, and its parts held to either side, inasmuch as a thin cellular * Dublin Dissector, p. 153. FEMORAL ARTERY. 241 oradipo.se stratum is interposed between tliem. The last particular in the disposition of the prolongation of the fascia transversalis, having reference to the femoral artery, is, that it is connected to the back of the femoral canal (the pubic portion of the fascia lata posterior to the vessels) by two septa or partitions, placed, one between the artery and vein, upon the inside of the former ; the other internal to the latter, between it and the femoral ring: by those the abdominal aperture of the femoral sheath is divided into three compartments : an external one occupied by the artery, a mid- dle one by the vein, and an internal by the lymphatics, and at times by a gland. The two former are so protected that the occurrence of hernia through them is rare ; in the case of the first probably impossible; but the internal, whether from weakness or deficiency of pro- tecting provisions, allows its protrusion, and hence the relation of the femoral vessels, and more particularly of the artery to the neck of the sac of femoral hernia, upon the outer side of which it is always situate, separated from it by the vein. At the lower part of the first stage the artery is crossed obliquely by the most internal of the deep branches of the crural nerve, which for distinction sake might be called internal geni- cular : it enters the femoral canal on the out- side of the vessels above, at a variable distance from Poupart's ligament ; descends from without inward upon the front of the artery within the canal ; and escapes from it below on the inside of the vessel under cover of the sartorius. Situate, as the nerve is, within the femoral canal, upon the front of the artery, and close'y connected to it by the femoral sheath, it is very likely, unless care be taken to avoid it, to be included in a ligature at the same time with the vessel : it will not, how- ever, be always encountered, inasmuch as it crosses the artery, and at a point higher or lower in different subjects. At times a second branch of the crural nerve crosses the artery in like manner as the former and lower down, but it is not to be always observed. Posteriorly in its first stage the artery rests, first upon the inner margin of the psoas magnus, from which it is separated by the deep lamina of the iliac portion of the fascia lata: while so related, it is situate over the anterior surface of the os innominatum, external to the iliopec- tineal eminence, having the two structures, already mentioned, interposed.* Below the * In this the author has ventured to differ from the account usually given of the relation of the artery to the os innominatum, according to which ( Boyer, Cloquet,) the vessel must be understood to be situate internal to the point mentioned, being said to lie upon the os pubis ; but in his opinion this is not correct. The artery lies on the psoas, which is not internal to the eminence, and upon the deep lamina of the iliac portion of the fascia lata covering the muscle, which at its most internal part is inserted into the eminence; consequently the vessel, which lies on the lamina, must be ex- ternal to that point of bone, and observation will be found to confirm this view. VOL. II. os innominatum it is placed over the head of the femur, from which it is separated by the same parts, and also by the capsular ligament of the articulation, and the synovial bursa, which exists between the front of the capsule, and the psoas and iliacus muscles. There are then in this situation two resisting surfaces against which compression of the vessel may be effected; and here also, as observed by Harrison, a tumour with pulsation may occur in case of effusion either into the bursa simply, or into the joint, when a communication exists between the former and the synovial membrane of the latter. Having passed the margin of the psoas and the head of the femur, the artery corresponds to the tendon of the psoas and iliacus, to the pectinalis, and to a small portion of the ad- ductor brevis, which parts it crosses obliquely in its descent : it is not, however, in contact with them, but is separated from them by a space of some depth occupied by cellular structure and vessels. The distance of the artery from the muscles varies according to circumstances : when the thigh is extended or rotated inward, it is increased; when, on the other hand, it is flexed or rotated outward,* it is diminished : in the former case, the artery is brought nearer to the anterior surface of the thigh by the extension, and by the rotation the lesser trochanter, which is in the middle and deepest part of the space, is carried back- ward from that surface. The vessels which occupy the interval be- tween the artery and the muscles are the pro- funda vein, the circumflex veins, and the femoral vein in part, they being next to the artery and immediately behind it ; posterior to them are, at times, the profunda artery, and at the upper part, according to circumstances, one or other of the circumflex arteries, when arising, as in ordinary, from it. External to the artery in its first stage are the psoas and iliacus muscles, the sartorius, the rectus, and the upper extremity of the vastus internus muscles ; from all which it is separated by the wall of the femoral canal. At the entrance of the artery into the thigh, and for about an inch below Poupart's liga- ment, the crural portion of the genito-crural nerve is contained within the femoral canal in immediate apposition with the vessel upon its outer side. External to it are situate also the crural nerve above, and itssaphena branch below. Except in rare instances, the profunda artery lies on the outer side of the femoral during a greater or less extent of its first stage ; but it is, unless occasionally near to its origin, at the same time posterior to it, and is subject to varieties in its relation which will be more particularly detailed in the description of that vessel. Internally the artery corresponds, though at a distance, to the pectinalis and adductor mus- cles. The femoral vein at the upper part is very nearly upon the same level ; the artery, however, is somewhat anterior to it, probably * Harrison. B FEMORAL ARTERY. from resting upon the psoas, while the vein corresponds to the pubes between that muscle and the pectinalis: hence the two vessels at their entrance into the thigh, allowance being made for the trifling difference which has been mentioned, lie side by side, the vein internal to the artery ; but as the former descends from the pubes, it recedes from the surface more than the artery, and at the same time inclines outward, and thus it becomes posterior to it at the lower part of the stage, so as to be con- cealed by the artery by the time it has reached its termination. It is included with the artery in the femoral sheath, and is separated from it by the external of the two septa, which have been described. In its second stage the relations of the artery differ considerably from those in its first. In the first place it is covered throughout by the sartorius, the muscle crossing it obliquely from without inward, and thence first overlapping it by its inner edge, and gradually extending over it until the vessel is directly covered by it. Secondly, it is in consequence covered by two laminae of the fascia lata enclosing the muscle; one superficial to it, the other beneath it, form- ing the front of the femoral canal ; it has then two new coverings, the muscle and the second lamina of the fascia. Thirdly, the femoral vein, which is very closely connected to the artery, is directly behind it, between it and the adduc- tor longus muscle, to which the artery corre- sponds posteriorly. Fourthly, it has no part deserving of attention upon its inside ; and, lastly, the saphenus nerve is within the femoral canal, along the outer side of the artery and anterior to it. The inferior third of the artery also presents some peculiarities of relation. The vessel is still covered by the sartorius; but here the muscle is more to the inner, as in the second stage it is more to the outer side of the vessel, not only connecting it in front, but also lying against its inner side, and the more so the nearer we approach the termination of the stage ; so much so indeed, that at its termina- tion, the artery, when injected, may be felt beneath the outer margin of the muscle ; and hence the difference between the mode of pro- ceeding with regard to the sartorius recom- mended generally to be adopted, when occasion arises for seeking the artery in its inferior third, and that to be pursued when the vessel is to be exposed in its second stage ; it being ad- vised, in the latter case, to displace the inner edge of the muscle outward, and in the former the outer inward, in order to reach the vessel with the greatest ease and certainty. The ves- sel is also covered by the same two laminae of the fascia ; but the deep one presents at this part remarkable features : it increases in thick- ness and is more aponeurotic in proportion as it descends, and hence it is stronger the nearer we approach the termination of the course of the artery ; but in the inferior third its thick- ness is still further augmented by numerous tendinous fibres, which pass from the tendons of the adductors longus and magnus to that of the vastus internus, add very much to the thickness of the fascia, and give to it the ap- pearance of a tendiuous expansion of great strength, connecting the tendons of the mus- cles, which have been mentioned, and covering the artery upon its anterior and internal sides- It is also to be observed that this accession of fibres from the tendons exists only in the infe- rior third of the artery's course, and not in its middle stage, and hence the covering of the vessel beneath the sartorius, or the anterior wall of the canal, is much thicker and stronger in the former than in the latter ; and hence also one of the difficulties encountered in getting at the vessel in the third stage. The artery in this third stage is situate upon the inside of the shaft of the femur, crossing it ob- liquely from before backward : it is not, how- ever, in contact with the bone, but is separated from it by the vastus internus muscle : it is enclosed, as before stated, between muscles ; the sartorius before and internal to it, the ad- ductors longus and magnus behind it, and the vastus internus on its outside. The other relations of the vessel in this stage are to the saphena vein, the saphenus nerve, the femoral vein, and the superficial superior internal articular artery. The first is situate between the femoral artery and the internal face of the thigh, for the most part along the inner margin of the sartorius, but varying some- what in this respect, lying at times upou the muscle, from its middle to its inner edge, and at others posterior to it. The saphenus nerve is placed at first, as in the second stage, exter- nal and anterior to the artery, but it crosses it at its termination and escapes from the canal, upon its inside, in company with the superficial articular artery, as the vessel is about to pass into the popliteal space. The femoral vein is behind the artery and somewhat external to it : the latter relation of the vein is expressly de- nied by Velpeau,* but after careful examina- tion the author does not hesitate to affirm it. The superficial superior internal articular artery, a branch of the femoral, is given off by the artery immediately before its termination ; it arises from the front of the vessel, descends nearly in the course of it, escapes from the femoral canal in company with the saphenus nerve, and, holding generally the same relation to that nerve which the femoral itself does, may hence be mistaken for that artery at the inferior pait of its course. Thus the relations of the vessel are here in several particulars the reverse of those in its former stages, and the methods most eligible for adoption in operation ought to be varied accordingly. Operation in its last stage is seldom required, but it may be necessary, as in wounds of the artery at that part, in which case the mode of proceeding with regard to the sartorius and to the artery should be the reverse of that recommended for the upper stage, the muscle being to be displaced inward in order to expose the artery, and the separation of the latter from the vein to be effected in the same direction. ' Anatomie dts Regiow, t. ii. p. 485. «d. 1. FEMORAL ARTERY. 243 At the termination of its third stage the artery passes into the ham and there receives the name of popliteal : it enters the popliteal region through an elliptical aperture situate to the inside of the femur at the junction of its middle and inferior thirds, and upon a plane with its posterior face, the longer diameter of which corresponds to the course of the artery, and which is circumscribed by the lower mar- gin of the united tendons of the adductor longus and the adductor magnus above, by the connection between the tendon of the adductor magnus and that of the vastus interims below ; by the tendon of the adductor magnus inter- nally, and by that of the vastus internus exter- nally : in passing through, the artery carries with it a prolongation of the femoral sheath, by which the popliteal vessels become invested and connected. Varieties. — The superficial femoral artery sel- dom presents a variation from itsaccustomed dis- position,so much so that it may almost be held to be uniform in this respect : however two forms of deviation have been observed, rare in occur- rence, but of great importance in a practical point of view. Two instances of the first ab- normal arrangement are recorded, one of which occurred to Sir Charles Bell, and has been pub- lished by him in Anderson's Quarterly Journal for the year 1826: the second is preserved in the Museum of the College of Surgeons, and has been described in the fourth volume of the Dublin Hospital Reports by Dr. Houston, Conservator to the Museum. In these cases the femoral artery divided into two vessels of nearly equal size, which pursued the usual course of the artery side by side and very close together, not, however, in contact, but contained in distinct compartments of the sheath and separated by a septum : hence the existence of the second artery might in operation easily pass unobserved, it not being brought into view by opening the sheath of the other. One was also larger than the other, and situate internal and on a plane posterior to it. In Bell's case the discovery was the consequence of the un- fortunate event of an operation for popliteal aneurism ; the operation was performed in the middle third of the thigh. The pulsation of the aneurism, which was arrested on the appli- cation of the ligature, returned after an interval of some seconds, and became nearly as distinct as before : it ceased again upon the third day, but the patient was carried off on the sixth day by an erysipelatous inflammation of the thigh. On examination after death, it was ascertained that the disposition, which has been described, was present, and that but one of the two vessels had been tied. The second form of deviation is a high bifurcation into the posterior tibial and peroneal arteries : of this an instance* has been recorded by Sandifort, in which the division took place immediately below Poupart's ligament ; and Portalf states that the crural artery has been seen to divide into two large branches shortly • Green on the Varieties in the Arterial System, and Sandifort, Observ. Anat. Pathol, iv. 97. t Anatomie Medicale, t. iii. p. 326. after its escape from the abdomen, and then there were two popliteal arteries : he further states that among individuals, in which the brachial artery was bifurcated higher than usual, the crural artery was so also in a remarkable proportion.* A division of the femoral artery into two trunks of equal size, running parallel and so near together, that they might be conveniently included in one ligature, is recorded by Gooch in the Philosophical Transactions for the year 1 775, it being the third instance in amputations of the thigh, in which he had observed such a lasus naturpect, which affect very much its relation to the femoral artery. Its general direction is downward, backward, and outward ; still more outward than the femoral : it is seldom how- ever direct, but describes one or more inflec- tions, by which its course is made at times to cross once or oftener that of the other vessel ; and hence the diversities in its relation to the femoral which have been adverted to. When the course of the vessel is direct or little tor- tuous, the profunda is situate throughout, external to the femoral, and this relation would appear to prevail at least as frequently as any • Op. cit. p. 328. t Treatise on Diseases of Arteries and Veins, p. 434. X On Diseases of the Heart, &c. p. 319, 20. i Ibid. [I JExplicalio Tabulanim Arteriaruin, p. 323. f Ibid. 246 FEMORAL ARTERY. other, or to be the most prevalent, for such is the view of the course of the artery given by Haller,* in two of three views in which the relative course of the two vessels is repre- sented, and by Tiedemannf in two of four views. But at other times, when the artery is more tortuous, after descending for a little way external to the femoral, it makes a turn, and passes inward behind it, and thus fre- quently gains the inner side of that vessel before it reaches the adductor longus, after which it again inclines outward toward its destination. Such is the view given of its course by Scarpa,^ with which the description of Harrison coincides : it is similarly repre- sented by Tiedemann in fig. 4, tab. xxxiii., and also by Haller § in one instance; but the author is disposed to regard this as a less common disposition, as well from the fre- quency with which he has observed the former one to occur, as from the weight of the autho- rities which have been adduced in favour of that opinion. In other but rare instances the profunda, arising from the inside of the femo- ral, inclines at first inward and becomes in- ternal to it, and then bending outward crosses behind the femoral to its outer side: of this arrangement an instance is furnished by Tiede- mann in fig. 3, tab. xxxiii. And in others the artery does not in the first instance incline sensibly to either side; but arising from the back of the femoral it descends behind that vessel, and does not gain its outer side until it has reached the lower part of the inguinal region. When the profunda artery arises very near to or above Poupart's ligament, and from the outer side of the femoral, is large and pursues its ordinary course, two arteries of equal or nearly equal size may be found, at the upper part of the inguinal region, side by side, and upon the same level, and thence liable to be taken, either of them, for the femoral artery. When such an arrangement occurs, the ex- ternal|| of the two vessels will almost certainly be found to be the profunda, for if that artery have once passed inward behind the femoral, it cannot afterward gain the same level with it, so as to be situate at the same time internal to and on the same plane with it : further, as the profunda descends, it recedes from the an- terior surface more than the femoral, in order to pass behind the adductor longus, and thus it gains at the lower part of the region a deeper situation than the other. But inasmuch as the profunda occasionally arises from the inside of the femoral artery, it may be possible for it, in case of high origin, to be the inner of the two vessels adverted to. Such a circumstance, however, if it ever occur, must be extremely rare, but in order to guard against it, the pre- * Icones Anatomies. t Tabulas Arteriarum. Tab. xxxi. and fig. 2. tab. xxxiii. % Reflexions et Observations Anatomico-chirur- gicales sur l'Aneurisme, tab. lire. $ Op. cit. || Harrison, op. cit. vol. ii. p. J65. Hargrave, System of Operative Surgery. caution recommended of alternately compres- sing the vessels and ascertaining the effect previous to the application of a ligature, should never be neglected. Branches of the profunda artery . — The pro- funda gives off a considerable number of branches, some of which being distributed to the muscles, by which the artery passes, and not being remarkable either for their size or their communications, have not received par- ticular names. Those which are most de- serving of attention, whether for their size, the extent and peculiarity of their course, or the anastomoses which they form with other arteries, are five or six in number, viz. two circumflex arteries, and three or at times four perforating arteries. The circumflex arteries are so named because they wind round the upper extremity of the femur, and form an arterial circle around it : they are distinguished by the epithets external and internal, being destined, one to the outer, the other to the inner side of the limb : they are vessels of considerable size and importance because both of the extent of parts which they supply, and of the communications which are established through them between the femoral, the arteries of the pelvis, and those of the lower parts of the limb. tt The external circumflex artery at times is the first branch of the profunda ; at others it is preceded by the internal circumflex : it is given off from the profunda while it lies on the outside of the femoral at a variable dis- tance from Poupart's ligament, and arises from the outer side of the artery : occasionally it is given off by the femoral itself; it runs directly outward, or outward and downward, in front of the psoas and iliacus muscles; beneath the sartorius and rectus, and either between or behind the divisions of the crural nerve ; and divides after a short course into three branches, viz. an ascending, a descending, and a circum- flex. a. The first, the ascending branch, runs up- ward and outward toward the superior anterior spinous process of the ilium, between the iliacus internus and the glutreus medius mus- cles, and concealed by the tensor vaginas femoris : as it proceeds, it gives branches to those muscles; and having reached the outer and back part of the spinous process, it ter- minates in an anastomosis with a branch of the glutceal, and also with the deep cir- cumflex ilii arteries. The anastomosis with the glutceal artery becomes remarkably en- larged when the main vessel is interrupted above the origin of the profunda, as may be seen from Sir A. Cooper's case of femoral aneurism.* b. The second, the descending branch, runs downward and outward beneath the rectus muscle, between it and the triceps crural, and divides after a short course for the most part into several branches of considerable size and great length for the supply of those muscles and for establishing communications : the branches are * Guy's Hospital Reports, Jan. 1836, pi* 1. FEMORAL ARTERY. 247 at times so many as five or six, and are dis- tributed one or more to the rectus, entering the muscle upon its deep surface, and pro- longed to a great length within its substance ; one to the vastus internus, one to the cruraeus, and one or two to the vastus extern us : they are accompanied, several of them, by branches of the crural nerve, and they run for a con- siderable distance, particularly the infe- rior branch to the vastus externus, between the divisions of the triceps crural muscle, before entering their substance : they are pro- longed very low down, and may be followed some of them to near the knee, where they anastomose with branches of the femoral in the vastus internus, and with the superior articular arteries. But the branches of the descending division of the external circum- flex artery are by no means uniform in number or destination, more or fewer of the arteries just described being at times branches of the profunda itself; thus, at times that to the vastus internus, that to the cruraeus, and that to the rectus, arise from the profunda below the circumflex, and in such case the descend- ing branch of the latter consists solely of the branch or branches destined to the vastus ex- ternus muscle. c. The third, the circumflex branch, pursues at first the course of the original vessel, and runs outward across the upper extremity of the shaft of the femur below the great trochanter, beneath the rectus and tensor vaginae muscles, and superficial to the cruraeus. It gives, in this situation, branches to the cruraeus, the iliacus, the rectus and tensor muscles. It then passes backward upon the outside of the femur to its posterior part, and thus surrounds the bone upon its anterior and external sides. In the latter part of its course it traverses the upper extremity of the vastus externus, and gives off, 1. branches upward and downward into the muscle; 2. a branch or branches which run between the vastus and the bone, and supply the periosteum ; 3. a branch to the gluteus maximus at its insertion, which, after furnishing it branches, perforates the muscle and becomes superficial. The circumflex divi- sion of the external circumflex anastomoses with the internal circumflex, the gluteal, the sciatic, and the perforating arteries. The ex- ternal circumflex artery is accompanied by a large vein, which crosses between the femoral and profunda arteries, superficial to the latter, in order to join the femoral or the profunda vein. 2. The internal circumflex artery is a larger vessel than the external : it is given off by the profunda usually after the external, and arises from the inner side of the artery, but at times it arises before the external. According to Harrison it " very frequently proceeds from the femoral artery, prior to the origin of the pro- funda ;" it has been found by Burns* arising from the external iliac artery, and also from the femoral artery a little below the crural arch. In the former case " it ran along the front of the lymphatic sheath f and in the second " it traversed the front of the common sheath of the great vein and also of the lymphatics ;" and in either case, as observed by Burns, it must be exposed to great danger in operation for femoral hernia. According to Green,* both circumflex arteries sometimes are furnished from a common trunk. It runs inward, back- ward, and downward toward the lesser tro- chanter into the deepest part of the inguinal region, and escapes from that spare posteriorly between the tendon of the psoas and the pecti- nalis muscles ; continues its course backward, on the inside of the neck of the femur and the capsular ligament, below the obturator exter- nus, behind the pectinalis, and anterior to the adductor magnus and the quadratus muscles, until it has got behind the neck of the bone; and lastly, it passes through the internal, which separates the inferior margin of the quadratus femoris from the upper margin of the adductor magnus, and thus gains the posterior region of the thigh, where it terminates as will be de- scribed. The internal circumflex artery is the vessel which gains the deepest situation in the groin : it is internal and posterior to the profunda, and when it arises from that artery, while external to the femoral, it crosses the latter vessel poste- riorly in its course. While within the inguinal region the internal circumflex artery gives off first a branch to the iliacus and psoas muscles: then a considerable branch, denominated by Tiedemann superficial circumflex branch, which contributes to supply the pectinalis, the adduc- tor longus, and the adductor brevis : it runs upward and inward upon the pectinalis, at the same time giving branches to it and to the ad- ductor longus, until it reaches the interval be- tween these muscles : it then divides into two, of which one ascends in the course of the original branch, between the muscles men- tioned, toward the origin of the adductor longus, supplying the two muscles, and ultimately anastomosing with branches of the obturator artery : small branches of it traverse the adduc- tor, and become cutaneous upon the upper and inner part of the thigh. The second branch passes downward and backward, also between the pectinalis and the adductor longus, gains the anterior surface of the adductor brevis, and there meets the obturator vessels and nerves: it divides into several branches, of which some are distributed to the last muscle, some anas- tomose with the obturator artery, and others with the upper perforating artery. Behind the pectinalis the internal circumflex artery gives several branches. Downward it gives a considerable one to the adductor mag- nus, which descends into that muscle, supplies it and anastomoses with the perforating arteries. Upward and forward it gives to -the adductor brevis and the obturator externus branches which communicate freely with the obturator artery after its escape from the pelvis. Out- ward it gives the articular artery of the hip a branch, small, but remarkable for its course and * Op. cit. p. 319. * Op. cit. p. 31. 248 FEMORAL ARTERY. destination ; it enters the articulation beneath the transverse ligament, through the notch at the internal and inferior part of the margin of the acetabulum, over which the ligament is thrown ; supplies the adipose structure which occupies the bottom of the socket, and is con- ducted by the ligamentum teres to the head of the femur, in which it is ultimately distributed. That part of the artery which reaches the head of the femur is of very inconsiderable size, and is the source upon which the nutrition of that part depends in fracture of the neck of the bone within the capsule. Lastly, upward and back- ward the artery sends off a considerable and regular branch which is usually described as one of its terminating branches, but which, in the opinion of the author, may with more pro- priety be considered as belonging to its middle stage. It passes upward and outward between the obturator externus and the quadratus mus- cles to the trochanteric fossa, where it is dis- tributed to the muscles inserted behind the trochanter, viz. to those which have been just mentioned ; to the obturator internus, the gemelli, the pyriformis, the glutei medius and minimus, and to the back of the ilio-femoral articulation, and where it inosculates with the gluteal, sciatic, and external circumflex arte- ries. It may be appropriately called the poste- rior trochanteric* branch. After its passage between the quadratus and the adductor magnus, the circumflex artery divides, in the posterior region of the thigh, into an ascending and a descending branch. The former passes upward to the origin of the biceps, semi - membranosus and tendinosus muscles, and to the gluteus maximus ; the latter downward to the former muscles, to the adductor magnus, and to the sciatic nerve. They communicate with the sciatic, the exter- nal circumflex, and superior perforating arte- ries. The perforating arteries are three or four in number. They are given off backward by the profunda, below the origin of the circumflex arteries, and are denominated numerically first, second, third, &c. They all pass from the an- terior to the posterior region of the thigh by perforating the adductor magnus, and at times also the adductor brevis, whence their name ; they divide for the most part into ascending and descending branches, and are consumed partly in the supply of that region, and partly in establishing a chain of communications be- tween the arteries of the trunk and the main artery at the upper and the lower parts of the thigh. 3. The first perforating artery arises from the profunda immediately below the lesser trochan- ter, nearly opposite the lower margin of the pectinalis : it passes backward, descending a little below the lower margin of the pectinalis, either between it and the upper one of the ad- ductor brevis, or through an aperture in the latter muscle : it next perforates the adductor magnus close to the linea aspera, and so gains the posterior region of the thigh, where it * Scarpa, op. cit. divides into two or three large branches, of which one ascends and is distributed to the gluteus maximus, communicating with the gluteal, sciatic, and circumflex arteries; ano- ther descends, supplies the long head of the biceps, the semi-membranosus and semi-tendi- nosus, and communicates with the inferior per- forating arteries ; and the third runs downward and outward into the vastus externus, through which it descends, communicating at the same time with the external circumflex artery. The artery also gives branches to the sciatic nerve, and, during its passage from the front to the back of the thigh, to the pectinalis and the ad- ductors. According to Hairison, f this artery is sometimes a branch of the internal circum- flex ; its course is nearly parallel to that vessel, and is separated from it by the tendon of the pectinaeus muscle, the first perforating artery passing below that teudon, while the circumflex artery runs superior to it." 4. The second perforating artery is generally the largest of those vessels : it arises a short distance below the first, and passes through both the adductors brevis and magnus ; it then divides, like the former, into ascending and de- scending branches : the former are distributed to the gluteus maximus, the vastus externus, and the tensor vaginae, likewise anastomosing with the first perforating, the gluteal, sciatic, and circumflex arteries : the latter are distri- buted to the biceps, semi-membranosus, and semi-tendinosus, the vastus externus, and the integuments of the back of the thigh, and in- osculate with the inferior perforating and with branches of the popliteal artery. The artery also gives branches to the adductor muscles and to the sciatic nerve and the nutritious artery of the femur, which enters a canal to be ob- served in the linea aspera, at the junction of the first and second thirds of the thigh, leading obliquely upward into the bone. The second perforating artery at times does not pass through the adductor brevis, but when the first does so, it generally runs inferior to it, perfora- ting the adductor magnus only. 5. The third perforating artery is smaller than either of the former, and arises lower down ; according to Harrison, at the upper edge of the adductor longus muscles, it passes through the adductor magnus, and divides in the same manner as the others : its branches are also similarly distributed, and anastomose with the second perforating artery from above, and with branches of the popliteal from below. When a fourth perforating artery exists, if. pursues a similar course and is distributed similarly to the last. The perforating branches of the profunda are subject to much varietj with regard to number, size, and precise course and distribution ; so much so that they hardly admit a definite description : the preceding ac- count has been taken from a comparison of the most approved authorities with the subject, in order, as far as possible, to embrace their nu- merous irregularities. Beside those branches, which have been enumerated, to which proper names have been given, the profunda artery gives off during its FEMORAL ARTERY. 249 course others less regular and less considerable, which are distributed to the muscles in its vicinity. Those are a branch to the pectinalis and adductor muscles, and one or more to the vastus internus and cruraeus muscles : it has been elsewhere stated that the descending branches of the external circumflex, destined to the last-named muscles, and one of those to the vastus externus, at times also arise from the profunda itself. After having given off the last perforating artery, the profunda, very much reduced in size, continues its descent behind the adductor longus muscle, inclining at the same time outward, and external to the femoral artery : it passes through the adductor magnus a little above the passage of the femoral into the ham, giving it small branches; then tra- verses the origin of the short head of the biceps, giving it also branches ; and, lastly, enters into the outer part of the vastus externus, through which it descends frequently to near the knee, distributing branches to the muscle, and anasto- mosing with the descending branches of the external circumflex and with the external arti- cular artery. The termination of the profunda is by some* called the fourth perforating artery. The profunda resembles very much in its course and termination the superior profunda or musculo-spiral branch of the brachial artery, to which it may be considered analogous. Immediately before the femoral artery passes into the popliteal space, it gives off its fifth and lowest branch. This is usually called the anastomotica magna artery, but there being no more reason to apply the epithet anastomotic to it than to the other brandies of the femora, and the great anastomotic artery of the thigh being in reality the profunda, the name given to it by Tiedemann seems much to be preferred, viz. superficial superior internal articular. It arises from the front of the femoral at the inferior part of its last stage, and immediately escapes from within the femoral canal, passing through its anterior wall at the same time with the saphenus nerve, as the femoral itself is about to pass into the ham. Having come through the aponeurosis forming the wall of the canal, it descends for some distance toward the inside of the knee parallel to the tendon of the adductor magnus and anterior to it in company with the saphenus nerve, and covered by the sartorius muscle. After a short course it divides into two branches. One of these runs down- ward and forward, in front of the adductor magnus, toward the patella ; enters the vastus internus and traverses it in its course ; divides within it into two branches, of which one runs between the muscle and the bone, and supplies the periosteum of the femur and the capsule of the articulation, anastomosing at the same time with the deep articulars; the other continues its course through the vastus, supplying the muscle, until it reaches the side of the tendon of the extensors : it then becomes superficial to the tendon, and descends upon the front of the patella, ramifying freely upon it, supplies the * Scarpa, op. cit. p. 17, 18. integuments and other superficial structures of the articulation on its anterior part, and com- municates freely with the other articular arte- ries. The second branch, into which the superfi- cial articular divides, descends posterior to the tendon of the adductor, in company with the saphenus nerve, and covered by the sartorius : as it descends, it gives branches to the ham- string muscles, the semi-membranosusandsemi- tendinosus, and also to the sartorius : when it has reached the inner side of the knee, it divides into two, of which one passes forward beneath the aponeurosis, upon the internal condyle of the femur, divides into branches which supply the superficial structures of the joint upon its inside, can be traced forward beneath the pa- tella, and form free communications with the other articular arteries, more particularly with the inferior internal one: the second descends to the leg, escapes from beneath the tendon of the sartorius, and then, turnin? forward, rami- fies over the internal surface of the tibia below its tubercle, supplies the insertions of the mus- cles and the coverings, and communicates with branches of the internal articular and of the tibial recurrent arteries. The superficial supe- rior internal articular artery is variable in size : at times it is of very considerable magnitude ; at others it is small, or even absent altogether, its place being supplied by a branch of the popliteal artery. Its distribution also varies with its size, the extent of the former being proportioned to the latter. The course of the artery diverges but little from that of the femoral, and the relation of the saphenus nerve to it is almost the same as that which the nerve holds to the latter vessel : hence, when the branch is large, it is liable to be mistaken in the operation of tying the main vessel, particularly in case of wound of the artery, for the femoral itself. The description of the articular artery here given has been taken from the plate of Tiedemann, in which the vessel is reprpsented with its most extended distribution. The femoral artery also gives off, during its descent through the thigh, beside the branches which have been described, several others to the muscles which are in its vicinity ; above, it sends branches to the sartorius, lliacus, and pectinalis; and in the middle of the thigh to the vastus internus on the one hand, and to the adductor muscles on the other. Those branches are for the most part inconsiderable in size, and have not received names, but they are de- serving of attention, inasmuch as they coope- rate in the collateral circulation, more particu- larly the second set, through which the femoral artery is generally preserved pervious, after ligature below the origin of the profunda, during a greater or less extent of the interval between the ligature and the popliteal artery, by means of the anastomoses between the branches in question and the circumflex arteries. The adequacy of the collateral circulation in the thigh to the maintenance and nutrition of the limb after the interruption of the femoral artery, has been so long established that it is 250 FEMORAL ARTERY. at present unnecessary to insist upon it. But the channels through which the circulation of the blood becomes in such cases restored, as well as the relations of the new circulation, are deserving of attention. The collateral connections of the femoral artery are distinguishable into those between it and the arteries of the trunk, those between it and the popliteal and arteries of the leg, and those between different parts of its own course. The communication of the femoral artery with the arteries of the trunk are established between it and both the internal and the external iliacs. Those with the internal iliac are formed, 1. by means of the inosculations of the branches of the profunda, the circumflex and perforating arteries with the obturator, glutceal, and sciatic arteries, all branches of the latter; 2. by those between the internal and external pudics ; and, 3. by the communications of the ilio-lumbar artery with the deep anterior iliac, by which the blood may be transferred to the superficial an- terior iliac or the external circumflex. From the obturator artery the bl ood is transmit- ted through theascending branches of the internal circumflex : this channel of communication be- comes, in cases of interruption of the external iliac artery, remarkably free, the branches esta- blishing it being much enlarged and tortuous : instances and representations of it may be found in the Medico-Chirurgical Transactions, vol. iv. and in Guy's Hospital Reports, IN o. 1, Jan. 1836, from the experience of Sir Astley Cooper. Through the glutceal artery the femoral com- municates with the internal iliac by the inoscu- lations between that vessel, the posterior tro- chanteric and the ascending terminal branches of the internal circumflex, and by those between it and the ascending and circumflex branches of the external circumflex artery : those connec- tions are displayed also in the works just referred to. The communication of the femoral with the internal iliac through the sciatic artery is esta- blished by the anastomosis of that vessel with the internal circumflex and the perforating arte- ries, for which also see the same works. The alteration in the condition of the sciatic artery or its branches caused by ligature of the femoral or of the external iliac artery presents one of the most remarkable results of that cir- cumstance : its branch to the sciatic nerve be- comes greatly enlarged, very tortuous, and so much elongated as to form at times a commu- nication between the sciatic artery and the posterior tibial. The connections established through the pudic and ilio-lumbar arteries are set forth, in the event of a case of ligature of the external iliac artery published in the Medico- Chirurgical Transactions, vol. xx. by Mr. Norman. The femoral artery communicates with the external iliac through means of the anastomoses between the anterior iliac arteries, internal and external, between the internal anterior iliac and the external circumflex ; and also by those be- tween the superficial and internal epigastrics. By the communications, which have been mentioned, the transmission of blood through the femoral artery may be restored, after the interruption of the external iliac artery, or of the femoral above the origin of the profunda, with sufficient freedom for the perfect nutrition of the limb ; of which numerous instances have been observed by different writers. The upper and lower parts of the femoral artery are also connected by collateral channels. Those are established by the communications which exist between the branches of the pro- funda artery arising from the upper extremity of the femoral, and branches of the latter given off during its course or from its lower extre- mity ; thus the blood may pass from the femo- ral artery above into the middle part of the vessel through the anastomosis existing between the descending branches of the external circum- flex artery, and the branches given by the femo- ral to the vastus internus muscle about the middle of the thigh. A similar communication exists upon the internal side of the femoral by means of the anastomoses by which descending branches of the internal circumflex are connected with those given by the femoral itself to the adductors. The collateral connection of the femoral with the popliteal artery is established through two channels: 1. through the anastomoses between the branches of the profunda, as well the ex- ternal circumflex as the perforating arteries, with the branches of the popliteal; whence the femoral may be interrupted at any part below the origin of the profunda, and the blood thus find a ready passage from it into the popliteal : 2. through those of the branches given by the femoral to the vastus internus and the superficial superior internal articular with the same. To the channels of communication which have been described are to be added, as pointed out by Scarpa, those established, by the arteries of the periosteum and of the in- ternal structure of the femur, between the main arteries above and below. The former are well represented by Scarpa,* and are formed by anastomoses between branches of the external circumflex, the profunda, the femoral and the popliteal distributed to the periosteum. Upon a review of the anastomotic con- nections of the femoral artery, its course pre- sents two stations at which communications are established, on the one hand with the main artery above, and on the other with that below, while in the interval they are connected the one with the other. Those are, 1. the first part of the vessel's course from its commence- ment to below the origin of the profunda ; and, 2. its lower part for so much of it as includes the origins of the branches to the triceps crural and adductor muscles, and the superficial superior internal articular. Again, it appears that through the first station, not only is the femoral connected with the arteries of the trunk and with the lower part of the vessel, but also it is connected * Reflexions sur l'Aneurisme, tab. ii. FEMORAL without the intermedium of the second with the popliteal artery, the latter forming by much the more free channel of communication be- tween the two vessels, whence the circulation of the lower part of the limb may be pre- served independent of the communication be- tween the upper and lower parts of the femoral artery, as has been exemplified in the case of Sir A. Cooper given in the Medico-Chirur- gical Transactions, vol. ii.; and, lastly, a com- munication exists by which the blood may be conveyed from the arteries of the trunk into the popliteal artery and the arteries of the leg, independent of the femoral and without trans- mission through any part of its canal. Hence varieties may be expected in the con- dition of the femoral artery in cases of inter- ruption, according to the situation of the interruption, and the influence of it or other circumstances in determining the course which the circulation is to take. When the artery is obstructed above the origin of the profunda independent of aneu- rism, the origin of that vessel being free from disease, it would appear that the trunk of the femoral does not undergo any alteration in its capacity, at least from the origin of the pro- funda downward : when an interval exists between the point of interruption and the origin of that vessel, the trunk may be di- minished for so much, while again it may continue unaltered ; thus in Sir A. Cooper's case* already referred to, the vessel was found reduced to about half its natural size between the origins of the epigastric and circumflex ilii arteries and that of the profunda, and from the latter it preserved its ordinary size through the remainder of its course : in Mr. Norman's casef on the other hand, it was of its natural size in the interval adverted to, but inasmuch as the origin of the profunda was obstructed in the latter case, it cannot be considered so fair an instance of the influence of the simple interruption at the part specified as the former, in which the femoral artery remained pervious after the cure of the aneurism. It is hence to be inferred, 1. that interruption of the femoral above the origin of the profunda or of the external iliac artery is not necessarily followed by obliteration of the former, unless it be of so much of the femoral as might intervene between the interruption and the origin of the profunda, where the ligature has been applied to the former: 2. that in such case the internal iliac is thenceforward the principal source from which the supply of blood to the lower extremity is to be derived ; and that the profunda artery through its inosculations with the branches of the internal iliac, constitutes the chief channel through which the transmission of the blood to the trunk of the femoral and the limb takes place : 3. that the external iliac artery con- tributes, but in an inferior degree, to the sup- ply of the limb, when the interruption is in the femoral itself : 4. that the femoral artery and its branches thenceforward are to be con- * Guy's Hospital Reports, t Med.-Chir. Trans, vol. xx. ARTERY. 251 sidered branches of the iliac arteries, rather of the internal than of the external, the trunk of the femoral itself being secondary to its own branches, by which the blood is transmitted into it from the iliacs. When the interruption of the femoral occurs below the origin of the profunda, the oblitera- tion of the trunk is no farther necessary than between the interruption and the origin of the profunda on the one hand, if no other branch intervene, and that of the next considerable branch upon the other. In such case the pro- funda artery becomes the main channel of the circulation through the lower extremity from its origin downward, and the femoral with its branches thenceforth are to be regarded as branches of it. But when the interruption arises from aneu- rism and the operation necessary for its cure, obliteration of the femoral, to a greater or less extent according to the case, for the most part ensues: this appears to depend upon the in- fluence, which the mode of cure of the disease exerts upon the circulation through the vessel, for the coagulation of the contents of the sac being generally produced by the interruption of the current of blood, the passage through the sac becomes obstructed, and along with it an extent of the artery upon both sides of the seat of the aneurism greater or less according to the disposition of the adjoining branches. The extent to which the obliteration of the artery has been found to proceed, has been different in different cases, but the varieties observed have been the following: 1. As re- gards that part of the vessel which is above the ligature, when the femoral artery has been tied below the origin of the profunda for po- pliteal aneurism, the vessel has been found, when the ligature has been applied to the lower part of the artery, either obliterated from the ligature to the origin of the pro- funda, as occurred in the first subject upon whom Mr. Hunter* operated for popliteal aneu- rism according to his method, or obliterated upward only as far as the origin of those mus- cular blanches of the artery, which arise below the profunda and anastomose with the articular arteries. 2. When the ligature has been ap- plied near to the origin of the piofunda, as in the operation of Scarpa, between it and the origin of the branches alluded to, the artery has been found obliterated from the point of interruption to the origin of the profunda. The condition of the artery below the seat of the ligature is equally subject to variety according to circumstances, and is still more deserving of attention than the former : it has been found in one of three states, either ob- literated throughout from the origin of the profunda down to the extremity of the popli- teal artery, as occurred in the case reported by Sir A. Cooper in the Medico-Chirurgical Transactions, vol. ii., or pervious throughout from the point of application of the ligature to the seat of the aneurism, where it was * Transactions of a Society for the improve- ment of Medical and Chirurgical Knowledge, vol. i. FEMORAL ARTERY. obliterated. Of this condition several in- stances are cited by Hodgson,* and a most remarkable one is in the possession of Mr. Adams of this city, through whose liberality the author is permitted to introduce a notice of it. It was obtained from a patient who had been operated on by the late Professor Todd, and is remarkable, 1. because the operation had been performed upon both limbs, and the condition of both is, as nearly as may be, the same; 2. because the obliteration at the seat of the ligature does not on either side exceed an inch, on one not being more than half that length ; and, 3. because the artery is pervious on both sides from the obliteration of the ligature to the lower part of the popliteal artery, the obliteration at the seat of the dis- ease appearing not to have extended beyond it; and being, on both sides, about two inches long. Thirdly, the artery has been found par- tially and irregularly obliterated, the vessel being closed at and for some distance below the seat of the ligature ; being then pervious, the blood being conveyed into it by the in- osculations between the minor branches of the artery arising below the interruption and those of the profunda from above ; and again im- pervious below, the blood being conveyed from it by similar branches anastomosing with the articular arteries. The effect of ligature of the external iliac upon the femoral artery, independent of the influence of aneurism, has been already ad- verted to. That effect is liable to be modified by the presence of the disease; thus in a case related by Sir A. Cooper in the fourth volume of the Medieo-Chirurgical Transactions, in which the iliac was tied for aneurism of the femoral artery at the middle of the thigh, the latter vessel was obliterated from the origin of the profunda downward. The case, re- corded by Mr. Norman, already referred to, in which the external iliac was also tied, presents another remarkable modification : in it the femoral remained pervious, but the root of the profunda was obliterated, while its branches were open. Operative relations of the femoral artery. — The femoral artery may be the subject of ope- ration at any part of its course, there being nothing either in its situation or relations to forbid the exposure of it at any point, if cir- cumstances should require it. All parts, how- ever, are not equally eligible, the vessel being in some situations more deeply situate, covered by a greater number and depth of parts, and its relations more complicated than at others. It has been taken up in each of the three stages into which its course has been divided, and the operations, which may according to circumstances be performed upon it, may with advantage be referred lo those. The propriety of thus distinguishing them will appear in a strong light, when tho.^e modifications, which the anatomical relations of the vessel may justify, shall have been discussed, as also from the history of the operations, which have been * Op. cit. 278, 9. and are proposed to be performed upon the femoral artery. In its first stage the vessel may be tied at two points, viz. either above or below the origin of the profunda artery : the operation at the former point, being performed under circumstances different from those in which that at the latter is admissible, may be con- sidered apart from the others, and the de- tail of it be postponed until they have been disposed of ; while the operation in the second case, and those in the second and third stages have been at different times performed for the same purpose — the cure of popliteal aneurism — and therefore a comparison of their several details and advantages merits attention. The situation in which the femoral artery was first taken up for popliteal aneurism is the third stage of its course : here it was tied, as is generally known, by J. Hunter. In his ope- ration Hunter made " an incision on the an- terior and inner part of the thigh rather below its middle;" i.e. in the third stage ; " which in- cision was continued obliquely across the inner edge of the sartorius muscle and made large :" the other steps of his operation it is not neces- sary at present to particularize ; the author would only remark, as a matter of history, that Hunter's application of ligatures has been mis- understood : he applied in bis first operation four ligatures to the artery, and it is com- monly, if not generally, said that they were drawn with various degrees of tightness ; but such was not the case, they were tied all equally tight : the account given in the report of the operation being, " the artery was now tied by both these ligatures," viz. the two upper, " but so slightly as only to compress the sides together. A similar application of ligatures was made a little lower. The reason for hav- ing four ligatures was to compress such a length of artery, as might make up for the want of tightness, it being wished to avoid great pressure on the vessel at any one part." The artery may be and has been frequently taken up in the middle stage, and the ope* ration, as described in several surgical works, will be found to belong to, if not to be in- tended for, that stage. During its two latter stages the artery is covered by the sartorius : in its uppermost it is not covered by the muscle, and consequently if it be necessary to displace the muscle to bring the artery into view above the last stage, it must be in the middle one, and in the account of the operation given by some of the highest authorities, the displace- ment of the sartorius is stated as one of the steps. This the author refers to not in a spirit of criticism, but in order to mark more strongly the distinction between the operations at the several stages, and to direct attention to the advantages possessed by that in the first over the others; more particularly since de- scriptions, which in strictness apply to the operation in the middle stage, and at a part of the artery's course below the first, may be found so put forward that the operations at the two points must be confounded; and thus the advantages contemplated by the proposer of FEMORAL ARTERY. 253 the latter be lost. It will be recollected that in the two inferior stages the artery is covered by the sartorius and by two laminae of the fascia lata, between which the muscle is situate : the vessel is, therefore, similarly cir- cumstanced in this particular throughout both, but in some other important respects the re- lations of the artery are different. 1. In its middle stage the vessel is nearer to the anterior plane of the limb. 2. The deep layer of fascia, by which it is covered, is far less thick and strong, particularly at its upper part. 3. The artery is not so completely covered by the sar- torius; and for those reasons the vessel may be more easily reached from before. These constitute the principal anatomical conside- rations why the middle stage should be pre- ferred to the lower for operation, but, since it is at times requisite to tie the vessel in its last stage, it is necessary to examine the influence which its anatomical relations may have upon the conduct of the operation at that part. 1. The greater depth of the artery from the anterior surface of the limb renders a more extended incision necessary : in cutting upon arteries " the centre of the incision should be," as directed by Guthrie, " if possible directly over that part of the artery on which it is in- tended to apply the ligature." In the case of the femoral artery in its third stage, the length of the incision should not be less than from four to five inches according to the volume of the limb ; its direction should correspond to that of the sartorius, but it must be varied somewhat according to the side of the muscle upon which the operator may purpose to seek the vessel. It should commence somewhat below the middle of the thigh, and be con- tinued as much upon the lower as upon the middle third of the limb. 2. The artery is situate, in its third stage, nearer to the outer than the inner margin of the sartorius, and the more so the nearer to its termination ; hence it may be exposed with greater ease and cer- tainty by cutting upon the outer edge of the muscle and displacing it inward. Hunter, in his operations, selected the inner margin, and displaced it forward and outward; but this proceeding is attended with disadvantages. 1. The saphena vein is more in the way and exposed to danger of being divided since it lies at this part, along or near the inner mar- gin of the sartorius. 2. The muscle lying more to the inner than the outer side of the artery must be more displaced, and the depth of the wound for the same reason greater when the vessel is sought from its inside.* 3. The ope- ration must be more inconvenient and em- barrassing, as well because of the former difficulties as because it must be performed more from the inside of the limb, and from within outward, than in the method by the * The contrary is maintained by Lisfranc and others ; but, according to the experience of the author, without sufficient reason. He has care- fully compared the depth of the wounds as made upon the opposite sides of the muscle, and in the subjects of examination that by the inside appeared to him the deeper. outer margin of the sartorius. Those objec- tions are avoided by cutting upon the outer edge of the muscle, against which, however, it has been advanced that in that method the vastus internus may be mistaken for the sar- torius, and that the wound being made from before, there is not a depending and ready outlet afforded to matter should it form, while by the other there is. The former of these objections cannot cany much weight, and for the second the best plan for obviating the dangers of inflammation and suppuration is, as much as possible, to render them unneces- sary, which is best accomplished by selecting that method by which the artery may be ex- posed most easily, and with least disturbance to the parts in its vicinity. To the writer, therefore, it seems that the method by the outer margin of the sartorius, which appears to have been suggested by Hutchison, is the more eligible in the operation for taking up the femoral in its third stage. 2. The great thickness and strength of the anterior wall of the femoral canal both increase the dif- ficulty of opening the canal, and render it desirable that that structure should be freely divided for the double purpose of facilitating the taking up of the artery, and preventing the injurious effect which must be produced by the confinement caused by the structure in question in the event of inflammation extend- ing along the vessel. 3. The relation of the vein to the artery at this part, viz. posterior and external, will make it more safe to pass the needle round the latter from without than from the outside ; this, however, is a rule which cannot be strictly adhered to, for the direction in which the instrument shall be passed must be varied according to circum- stances ; it would be difficult to pass it from the outside in case the artery were exposed from the inside of the sartorius ; but attention to the caution demanded by the position of the vein is, for this reason, only the more necessary. 4. The saphenus nerve being here within the femoral canal is to be carefully avoided ; it will be so with certainty, if the needle be carried from the outside 5 The mistake of confounding the superficial sune nor internal articular artery with the femoral must be also avoided* This mistake, which has occurred, ought not however to occur again ,„ the hands of a well-informed surgeon, for the possibility of it ought not to be lost sight of in operations at the lower part of the thigh; and it may be easily avoided by re- collecting, first, that the femoral itself is within the femoral canal, and therefore that any vessel, which presents before the division of the anterior wall of the canal, which is so remarkably thick in this situation that it can hardly be overlooked, cannot be the one which is sought for; and, secondly, that the course of the branch within the canal, after its origin is very short, and therefore that in case of°do'ubt the vessel which presents, must, if the arti- cular, conduct us directly to the trunk itself, * See that vessel. 254 FEMORAL ARTERY. when followed upward for a very short dis- tance. Lastly, the structures to be divided or put aside in order to expose the artery are, — 1. the skin; 2. the subcutaneous cellular stratum; 3. the superficial lamina of the fascia lata, forming the anterior wall of the sheath of the sartorius; 4. the sartorius itself; 5. the deep lamina of the fascia forming the posterior wall of the sheath of the sartorius, and the anterior wall of the femoral canal ; and, 6. the proper sheath of the vessels. The difference between the anatomical re- lations of the operation in the middle and inferior stages of the artery depends upon the modifications to be observed in the relations of the vessel at the two points, and also in some of the parts concerned. The number and order of the structures interposed between the surface and the artery are the same as in the third, but their disposition and relations differ in some important particulars so much as to authorize a difference in the proceedings to be adopted, and to justify a preference in favour of the former. 1. The artery is nearer to the anterior surface of the limb, and the more so the nearer to the commencement of the stage : it is therefore more easily reached and in the same proportion. 2. It is nearer to the inner than the outer margin of the sar- torius, and, in like manner, the more so, the nearer to its upper extremity ; and hence it may be brought into view with more ease and with less disturbance of the muscle by dis- placing its inner margin outward, than its outer inward. The latter proceeding is advocated by Hut- chison for the purpose of avoiding the sa- phena vein and the lymphatics. That the vein will be effectually secured from danger by cutting upon the outside of the sartorius will be at once admitted ; but it appears to the author that the advantage contemplated will be more than counterbalanced by the dis- advantages attending it, and on the other hand that the proceeding is not necessary: for, 1. if the outer margin of the muscle be cut upon in the middle of the vessel, the incision must be made considerably external to the line of the artery's course, and thereby the guide to the vessel otherwise afforded by that line must be lost, and uncertainty and consequently embarrassment be likely to ensue in seeking for the artery after having displaced the muscle. 2. Much more disturbance and violence are likely to be inflicted upon the artery and the adjoining parts by the plan in question, in- asmuch as the vessel is so much nearer to the inner than the outer margin of the muscle ; in consequence of which the muscle must be displaced to a much greater extent in proceed- ing from without inward, and the obstruction offered by it to the performance of the other steps of the operation must lead to greater violence either to the artery or to the muscle ; and afterward a valvular wound must be left, a circumstance very unfavourable in the event of the occurrence of inflammation and sup- puration in the vicinity of the track of the vessel, and those objections are the stronger because the artery is usually sought at the upper part of the stage, where it is but little overlapped by the muscle. On the other hand the saphena vein ought not to be endangered in the operation, for it is situate so far internal to the artery that the incision ought not to fall upon it. The case is different from that of cut- ting upon the inner margin of the sartorius during the third stage of the vessel ; for there the vein is for the most part close to the edge of the muscle, and the wound must be in- clined in depth from within outward, by which direction the vein is interposed between the surface and the artery ; whereas, in the second stage, whether the operator, in proceeding by the inner margin of the muscle, cut directly upon the artery's course or upon the edge of the sartorius, there is sufficient space between it and the vein to leave the latter safe. The course of the artery may be crossed at any part by the superficial femoral veins, as has been explained, and they, if they present, will be in danger of division ; but this inconvenience would not be removed by the plan in question, whereas both it and the danger to the saphena may be avoided by an easier and less ob- jectionable proceeding than that of cutting upon the outer edge of the sartorius, viz. 1. by ascertaining, through means of pressure, the situation and course of the veins ; and, 2. by proceeding with somewhat more caution, where there is reason to expect their presence, dividing first only the skin and continuing the incision through the subcutaneous structure, not by a single stroke, by which the vein if in the way must necessarily be divided, but gra- dually, until the vessel has been exposed and drawn aside. It seems therefore to the author not only unnecessary, but very objectionable to cut upon the outer margin of the sartorius, in exposing the femoral artery above the mid- dle of the thigh. 3. The anterior wall of the femoral canal is much thinner than in the third stage, and therefore more easily ma- naged. 4. The vein is directly behind the artery, and therefore the needle may be passed with equal safety from either side, according to circumstances : in operating by the inner margin of the sartorius it will be more easily done from the inside : the position of the vein and its close connection to the artery render it especially necessary that the extremity of the needle be kept in contact with the artery in being carried behind it. The saphenus nerve requires the same attention as in the third stage. But the situation in which it is at present generally considered most eligible to expose the artery for the application of a ligature, when circumstances do not forbid a choice, is that recommended by Scarpa, viz. in the upper third of the thigh, and in the first stage of the artery's course as described in the account of the anatomical relations of the vessel. In his description of the details of the operation, Scarpa directs thus : " The surgeon pressing with his fore-finger will explore the course of the superficial femoral artery, from the crural FEMORAL ARTERY. 255 arch downward, and when he comes to the place where he does not feel any more, or very confusedly, the vibration of the artery, he will there fix with his eye the inferior angle or ex- tremity of the incision which he proposes to make for bringing the artery into view. This lower angle of the incision will fall nearly on the internal margin of the sartorius muscle, just where this muscle crosses the course of the femoral artery. A little more than three inches above the place pointed out, the surgeon will begin his incision and carry it along the thigh in a slightly oblique line from without inwards, following the course of the femoral artery as far as the point fixed with the eye." By this incision the skin and cellular substance are to be divided, and the fascia lata exposed, " then with another stroke of the bistoury, with his hand free and unsupported, or upon a furrowed probe, he will divide along the thigh, and in the same direction as the external wound the fascia, and introducing the fore-finger of his left hand into the bottom of the incision, he will imme- diately feel the strong beating of the artery, and this without the necessity of removing the in- ternal margin of the sartorius from its position, or at least very little. With the point of the fore-finger of the left hand already touching the artery, the surgeon will separate it from its lateral connexions and from the vein;" after which the ligature is to be carried round it by means of a blunt aneurism-needle. The author has introduced the preceding account ia order to fix the precise situation of the operation as performed by Scarpa, because it appears to him that it has been to a certain degree lost sight of, and also to direct attention more strongly to the advantage proposed by that distin- guished surgeon in the adoption of the method which he has recommended. A very brief consideration of the descriptions given by se- veral writers* of the proceedings to be adopted in the operation of taking up the artery in the upper part of the thigh will suffice to shew either that Scarpa's method has been con- founded more or less with the operation at a lower point, or that its advantages have been disregarded: thus, while it is stated that the part of the limb in which the femoral artery can be tied with the greatest facility is between four and five inches below Poupart's ligament, and which is Scarpa's point,f the displacement of the sartorius is accounted a part of the ope- ration, and it has even been debated whether the incision should not be made on the outer edge of the sartorius, and the artery exposed by drawing the muscle inward ; but the dis- placement of the sartorius is not only not a necessary part of Scarpa's plan, but is that particular the avoidance of which he proposed to himself by the method he selected ; from whence it will appear that the operation, as described in the accounts alluded to, refers, strictly speaking, to the second and not to the first third of the vessel's course, within the latter of which it must be performed in order * Hodgson, &c. t The distance at which the sartorius crosses the artery varies according to the stature. to avoid the sartorius. . The structures to be divided in this operation are, 1. the skin, 2. the subcutaneous cellular structure, 3. the fascia lata, forming the anterior wall of the femoral canal. The extent of the superficial incisions need not exceed three inches, com- mencing above either according to the rule of Scarpa or about two inches below Poupart's ligament : the direction in which they should be made ought to correspond as nearly as pos- sible with the course of the artery. The extent to which the fascia lata is to be divided is stated differently by different writers : by some it is directed to be divided to the extent of about an inch : the direction of Scarpa is not precise upon the point in the text, though it is plain that he intended it should be divided to a much greater length than an inch, but in a note it is strongly insisted that the division of the fascia should correspond in extent to that of the external wound. Two reasons present for this : 1. greater facility in the performance of the operation, and less disturbance in con- sequence to the artery ; 2. the avoiding the injurious effects which must be produced by the confinement consequent upon too limited a division of the fascia in the event of the supervention of inflammation. It cannot be doubted that a division of an inch is altogether too short to meet those considerations, and that the fascia ought to be divided to a greater ex- tent ; on the other hand it does not appear that advantage would be gained by so free a divi- sion as that recommended by Scarpa ; and the rule of Guthrie seems the best calculated to ac- complish the ends in view : he advises the fascia to be divided for the space of two inches. The division may be effected either with or without the assistance of the director. It will be well to recollect here that, at the point at which the sartorius is about to overlap the artery, a du- plicature of the fascia takes place in order to enclose the muscle, and hence that, if the opening of the canal be attempted at the lower extremity of the stage, and close to the muscle, two layers of the fascia may require to be di- vided before this purpose can be accomplished. The femoral canal having been opened by the division of the fascia lata, the next step in the operation is the division of the proper sheath of the vessels and the insulation of the artery. Previous to this, should the internal genicular nerve be found to cross the canal superficial to the artery at the part, at which the vessel is to be detached from the contiguous parts, it should be separated and drawn outward. The insulation of the artery Scarpa recommends to be effected with the finger, raising the vessel from the wound even along with the vein if necessary; such a proceeding, however, must be very objectionable, as inflicting great dis- turbance and violence upon the artery. It is to be recollected that in order to insulate the artery it is necessary to divide or lacerate the investment, which immediately encloses the two vessels and connects them to each other, and which has been elsewhere denominated the femoral sheath ; this, though thin, is dense, and is to be expected to offer resistance to the 256 FEMORAL ARTERY. separation of the artery from the vein : the best method of effecting this, as it seems to the author, will be, after having opened the sheath directly over the centre of the artery either by a touch of the knife or first nipping up a part of it with the forceps ; making an aperture into it with the blade of the knife held horizon- tally, and extending the opening upon a di- rector to the length of " three-quarters or an inch," as recommended by Guthrie ; then with the forceps to take hold of each portion of the sheath in turn and drawing it to its own side, outward or inward as the case may be, to de- tach the artery from it with the extremity of a director or of the aneurism-needle, moving the extremity of the instrument gently upward and downward at the same time that the vessel is carried, by means of it, in the opposite direc- tion from the side of the sheath which is in the forceps ; by this proceeding the artery may be easily and safely insulated almost, if not quite, round, and with little if any disturbance to it. That done, the needle and ligature may be carried round the artery : the performance of this, which is the most delicate step in the operation, will be found much facilitated by the separation of the artery as recommended ; in fact, little more will then remain than to pass the needle, the passage having been al- ready opened. In doing so it will be well to hold the inner portion of the sheath, with the forceps, inward and backward, by which the vein will be drawn away from the artery, and at the same time to insinuate the blunt extre- mity of the aneurism-needle round the artery from within outward, because of the situation of the vein, moving it, if any obstruction be encountered, upward and downward, while it is also carried forward, and bearing the artery somewhat outward with it at the same time ; when the extremity of the needle has appeared on the outside of the artery it may be liberated, if necessary, by a touch of the scalpel upon it. In the execution of this manoeuvre two acci- dents are to be avoided, viz. injury of the vein, and inclusion of the saphenus nerve : the close juxta-position and attachment of the former to the artery render much care neces- sary to leave it uninjured; but the proceeding recommended will, if carefully executed, cer- tainly preserve it from being wounded. The saphenus nerve is here on the outside of the artery, and might be included within the liga- ture if the extremity of the needle were carried too far outward ; the operator should therefore assure himself, before tying the ligature, that the nerve has not been included ; but the risk of this accident ought not to be great at this part of the artery's course, certainly not so much so as at a lower point, inasmuch as the nerve has as yet hardly entered the femoral canal, and is therefore separated from the ar- tery by more or less of its outer wall; and with the precautions recommended in insulating the vessel and passing the ligature it will almost certainly be excluded at every part : the possi- bility of the accident is, however, not to be lost sight of. The needle having been carried round the artery, the ligature is to be taken hold of with the forceps, and one end drawn out, after which the needle is to be withdrawn. The advantages of the part chosen by Scarpa for this operation are numerous and obvious : 1. the artery is nearer to the surface and has fewer coverings; there is therefore less to be divided in order to bring it into view; 2. the vessel being more superficial, its pulsations can be more distinctly felt and its course ascer- tained previous to operation, a guide wanting in the lower parts of the thigh ; 3. " the ope- ration is done," as Guthrie observes, " on that part of the artery which is not covered by muscle, and all interference with the sartorius is avoided : this method obviates all discussion as to placing the ligature on the outside of the muscle." The plan of cutting upon the out- side of the sartorius in the upper stage of the artery must be, if contemplated by any, a pro- ceeding hardly defensible in the ordinary dis- position of the muscle, for all the reasons ad- vanced already against its use in the second stage apply with much greater force to it in the former case ; but it is at the same time to be observed that the distance of the point at which the muscle crosses the femoral artery is not ab- solutely regular, and that great deviation in this respect might render it necessary even to cut upon the outer margin of the muscle in order to expose the artery in the first third of its course. The distance from Poupart's liga- ment at which the muscle ordinarily crosses is, according to the stature, from three and a half to five inches, but it may in certain cases be found to cross so much sooner that the artery could not be exposed below the origin of the profunda without displacing the muscle ; thus Burns* mentions that he has seen, in conse- quence of malformation of the pelvis, the artery covered by the muscle, before it had reached two inches below the ligament, and the author has witnessed the same from retraction of the thighs, consequent apparently upon long con- finement to bed ; in the latter case it would certainly have been more easy to expose the vessel from the outer than from the inner side of the muscle ; but such cases are to be re- garded only as exceptions to be borne in mind, but not to influence our general conduct. 4. The performance of the last and most deli- cate parts of the operation must be much more easy and less embarrassed, the interference of the sartorius being avoided; while, on the other hand, all apprehension on account of the pro- funda is removed, since that vessel seldom, if ever, arises farther than two inches from Pou- part's ligament, and the course of the case after operation is more likely to be favourable and exempt from untoward occurrences, since much less violence must be done, and the superven- tion of injurious inflammation or its conse- quences thereby prevented. The operation for taking up the femoral ar- tery above the origin of the profunda is not often required, and, except in case of wound, may pro- bably give place altogether to that of tying the external iliac : it presents no advantage over * Op. cit. p. 321. FIBRINE. 257 the latter, it does not promise more successful results : should secondary hemorrhage succeed to it, there is little prospect that the ligature of the iliac would afterward succeed, and the uncertainty existing with regard to the point of origin of the profunda raises a very strong ob- jection against it, inasmuch as we cannot know whether the origin of that vessel be above, below, or at the point at which the ligature is to be applied : it is further exposed to the difficulty, before adverted to, which is likely to arise in cases of high origin of the profunda, in which that vessel may be taken for the femoral, and thus another source of embar- rassment be encountered. In the performance of it the following struc- tures will present : 1. the skin ; 2. the subcu- taneous cellular stratum along with the inguinal glands and the superficial inguinal vessels of the latter : those which are most exposed to be divided are the superficial epigastric and its branches ; the superficial anterior iliac and the superficial pudics may be encountered, but they are less likely; 3. the superficial lamina of the iliac portion of the fascia lata; and 4. the prolongation of the fascia transversalis, which forms the front of the femoral sheath. An incision three inches long will suffice ; it should commence above Poupart's ligament, and be continued in the line of the vessel for two inches below it. If the superficial vessels bleed, on division, so much as to interfere with the course of the operation, they should be at once secured ; otherwise they will probably cease themselves, and give no further trouble. The lymphatic glands, if in the way of the incisions, may be either held aside or removed. The fascia lata and sheath may be treated in the same manner as in the other operations described ; they can be easily distinguished in consequence of the thin stratum of fat which is usually interposed. The insulation of the artery and the passage of the needle require the same precautions as in the operations at other parts of the vessel's course. The vein being placed along the inside of the artery the needle should be passed from that side. The crural nerve and its branches are here altogether safe, as they lie without the femoral canal, but, as has been before pointed out, the crural branch of the genito-crural nerve may be included in the ligature; it will be most certainly avoided by the careful insulation of the artery: the operator should also assure himself, before tying the ligature, that no fila- ment is enclosed. Should two arteries present, as described in the anatomy of the profunda, and a question arise as to which is the femoral, the criteria pointed out will enable the operator to decide (see profunda artery ) ; and the difficulty will, almost certainly, be altogether avoided by cut- ting directly upon the centre line of the femoral as ascertained by its pulsations. Operation on the profunda artery. — From the anatomical details it follows that in the ma- jority of cases the profunda is situate, in the VOL. II, first stage of its course at least, at the outer or iliac side of the femoral artery, though upon a plane posterior to that vessel : it has also, at the same time, the same coverings, differing only in being contained in a sheath proper to itself; and hence, if necessary, the profunda might be reached in that situation by an opera- tion similar to that for exposing the femoral itself at the same place, in which much advan- tage would be obtained by first exposing the latter vessel, and following it as a guide to the origin of the former ; which, if in its usual situation, will be exposed by displacing the femoral inward, and then the proper sheath of the profunda should be opened to a certain ex- tent, in order to allow the application of the ligature at a sufficient distance from the origin of the vessel. But in the inferior stages of its course it may be laid down, as a general rule, that it cannot be reached from the front of the thigh, inasmuch as, with the exception of those cases in which it is throughout external to the femoral, and in which, from its deep position, and the want of a guide to its exact situation, the rule will yet equally apply, it is not only more deeply seated, but it is separated from the anterior surface of the limb by the super- ficial femoral artery, and by the femoral, pro- funda, and circumflex veins, as well as by the coverings of the femoral vessels, and lastly by the adductor longus muscle. In any case, did circumstances render necessary the attempt to tie the profunda, it would be an operation in which much uncertainty and difficulty must be anticipated, in consequence of the varieties presented by that artery in its origin and course. For Bibliography see ANATOMY (INTRODUC- TION), and A RTEU Y. ( B. Alcock.) FIBRINE, {Ywfibrine; Germ. Faserstoff.) Under this name physiologists and chemists have generally described the animal proximate principle constituting that part of muscular fibre which is insoluble in cold water, and that portion of the coagulum of blood which re- mains after the removal of its colouring matter. The fibrine of blood is best obtained by stirring a quantity of fresh-drawn blood with a piece of wood, to which the coagulum adheres, and may afterwards be washed in large and repeated portions of water till it loses its co- louring particles, and remains in the form of a buff-coloured, fibrous, and somewhat elastic substance ; this may then be partially dried by pressure between folds of blotting-paper, di- gested in alcohol to remove fat, and then care- fully dried, during which process it loses about three-fourths of its weight, and becomes brittle and of a yellowish colour: it is insipid and in- odorous. In cold water it slowly resumes its original appearance but does not dissolve : when, however, it is subjected to the long- continued action of boiling water it shrinks and becomes friable, and a portion of a newly- formed substance is at the same time taken up by the water, which gives it a yellowish colour and the smell and taste of boiled meat, and s 258 FIBRINE. which, when obtained by evaporation, is brittle, yellow, and again soluble in water : this solu- tion is rendered turbid by infusion of galls, but the precipitate differs from that yielded by gelatin, and appears to be a distinct product. The insoluble residue has lost its original cha- racters; it no longer gelatinises with acids or alkalies, and is insoluble in acetic acid and in caustic ammonia. The action of acids and alkalies upon the fibrine of blood has been studied in detail by Berzelius and others ; the following is an ab- stract of their results. * All the acids, except the nitric, render fibrine transparent and gelatinous : the diluted acids cause it to shrink up. In sulphuric acid it acquires the appearance of a bulky yellow jelly, which immediately shrinks upon the addition of water, and is a combination of the acid and fib rine ; when well washed upon a filter it gra- dually becomes transparent and soluble, and in that state is a neutral sulphate of fibrine. It is again rendered opaque by dilute sulphuric acid, and is precipitated from its aqueous solu- tion by that acid in the form of white flakes, which appear to be a supersulphate. When fibrine is heated in sulphuric acid, both are decomposed, the mass blackens, and sulphu- rous acid is evolved. If the colouring matter has not been entirely washed out of the fibrine, the sulphuric solution is of a brown or purple colour. Nitric acid communicates a yellow colour to fibrine, and, if cold and dilute, combines with it to form a neutral nitrate, analogous to the sulphate When fibrine is digested in nitric acid, nitrogen is evolved, and its composition considerably changed, as we shall more parti- cularly mention in describing the action of this acid on muscular fibre. Muriatic acid gelatinises fibrine and then gradually dissolves it, forming a dark blue liquid, or purple and violet, if retaining any haematosin. This solution, when diluted with water, deposits a white muriate of fibrine, which, like the sulphate, gelatinises when the excess of acid is washed away, and becomes soluble, and is again thrown down from its aqueous solution by excess of acid. The blue liquid, after the separation of the precipitate by dilution, retains its colour, but loses it when saturated with ammonia, and with excess of ammonia becomes yellow. Fibrine digested in dilute muriatic acid is converted into the same white compound as that precipitated by water from the concentrated muriatic solu- tion. Wrhen boiled in the acid, nitrogen is evolved, and a solution is obtained, which, after the saturation of the acid, is precipitated by infusion of galls, but not by alkali or ferrocy- anuret of potassium ; on evaporating the solution to dryness a dark brown saline mass remains, so that the fibrine appears to have undergone some decomposition. * Berzelius, Lehrbuch der Thier-Chemie, Woh- ler's German translation. Dresden, 1831. See also Medico-Chirurgical Transactions, vol. iii. p. 201. A solution of recently-fused phosphoric acid acts upon fibrine in the same way as the sul- phuric acid ; but if the acid solution has been kept for some weeks, the fibrine then forms with it a soluble jelly, which is not precipitated by excess of acid. Concentrated acetic acid converts fibrine into a jelly easily soluble in warm water. When this solution is boiled, a little nitrogen is evolved, but nothing is precipitated ; when gently eva- porated, it gelatinises, and leaves, on desic- cation, an opaque insoluble residue. The other acids added to this acetic solution produce precipitates which are compounds of fibrine with the added acid. Fibrine is also preci- pitated from the acetic solution by caustic pot- assa, but is redissolved by excess of alkali. The acetic solution of fibrine is precipitated in white flakes by ferrocyanuret of potassium : this precipitate, when dried, appears to be a compound of fibrine with cyanuret of iron and hydrocyanic acid; it is insoluble in dilute acids, but is decomposed by caustic alkalis, which abstract the cyanuret of iron and hydro- cyanic acid, and the remaining fibrine first gelatinises and then dissolves. 100 parts of this compound, carefully dried at 167°, and then incinerated in a weighed platinum cru- cible, gave 2.8 red oxide of iron,=7.8 of the combination of cyanuret of iron with hydro- cyanic acid; whence it follows that 92.2 of fibrine were contained in the white precipitated compound. Caustic potassa, even much diluted, dissolves fibrine. If the solution is very dilute, the fibrine gradually forms a bulky jelly, which, heated in a close vessel to about 130°, dissolves into a pale yellow liquid, not quite transparent, and which soon clogs a filter. The yellow tint appears to arise from the presence of a small portion of adhering haematosin. When this alkaline solution is saturated by muriatic or acetic acid, it exhales a peculiar fetid odour and blackens silver, announcing the presence of sulphur, so that the animal matter seems to have suffered some slight change. It is stated by Berzelius that fibrine is capable of neutral- izing the alkali, and that such neutral com- pound may be obtained by dissolving the fibrine in the alkaline solution, and adding acetic acid till it begins to occasion a precipi- tate ; the filtered liquid is then perfectly neu- tral, but the potassa bears a very small propor- tion to the fibrine. This neutral solution, he says, much resembles white of egg, and is coagulated by alcohol and acids, though not by heat. Gently evaporated, it gelatinises, and, when dry, assumes the appearance of albumen dried without coagulation. In this state it dissolves in warm water, and is first thrown down, and then redissolved by the acids when added in excess. Alcohol throws down nearly the whole of the fibrine from its neutral alkaline solution : if there be excess of alkali, much of the fibrine is retained. Mr. Hatchett found that fibrine, when digested in strong caustic potassa, evolved ammonia and yielded a species of soap; acids occasion a precipitate in this solution which is altered fibrine, for it neither gelati- FIBRINE. 259 hises nor dissolves in acetic acid: ammonia acts as potassa, but less energetically. When fibrine is digested in solution of per- sulphate of iron, or of copper, or of perchlo- ride of mercury, it combines with those salts, shrinks up, and loses all tendency to putre- faction. When the alkaline solution of fibrine is decomposed by metallic salts, the precipitate consists of the fibrine in combination with the metallic oxide; some of these compounds are soluble in caustic potassa. Tannin combines with fibrine, and occasions a precipitate both in its alkaline and acid solu- tions: the tanned fibrine resists putrefaction. The ultimate composition of fibrine has been determined by Gay Lussac and Thenard, and by Michaelis, who made a comparative ana- lysis of that of arterial and venous blood : the following are their results: — Gay Lussac Michaelis. and Thenard. Arterial. Venous. Nitrogen ..19.934 17.587 17.267 Carbon ..53.360 51.374 50.440 Hydrogen 7-021 7.254 8.228 Oxygen ..19.685 23.785 24.065 100.000 100.000 100.000 The mean of these results gives nearly the fol- lowing atomic composition : — Atoms. Equivalents. Theory. Nitrogen 1 14 19.72 Carbon 6 36 50.70 Hydrogen 5 5 7.04 Oxygen 2 16 22.54 1 71 100.00 In reference to this atomic estimate, which is suggested by Leopold Gmelin,* Berzelius observes, that from the feeble saturating power of fibrine, its equivalent number is probably very high, that is, that it includes a larger number of simple atoms; but as we have at present no accurate means of determining its combining proportion or saturating power, its atomic constitution cannot be satisfactorily determined. Moreover, it appears that in the above analyses the fat was not separated, nor is any notice taken of the minute portion of sul- phur, the presence of which has been above adverted to. When Berzelius first obtained fat from fibrine by digesting it in alcohol and in ether, he con- cluded that it arose from the decomposition of a portion of the fibrine by those agents ; that it was a product and not an educt; but the sub- sequent experiments of Chevreul leave no doubt that the fat exists ready formed in the blood. This fat is very soluble in alcohol, and the solution is slightly acid; when it is burned, the ash, instead of being acid, like that of the fatty matter of the brain, is alkaline, whence it appears that it existed saponified, or partly so, in the blood. Another important variety of fibrine is that which constitutes muscular fibre, but it is so interwoven with the nerves and vessels and cellular and adipose membrane, that its pro- perties are probably always more or less modi- * Handbuch der Theoretischen Chemie. fied by foreign matters. The colour of muscles appears to depend upon that of the blood in their capillary vessels; and their moisture is referable to water, which may be expelled by drying them upon a water-bath, when they lose upon an average 75 per cent. If muscular fibre in thin slices is washed with water till all soluble matters are removed, the residue, when carefully dried, does not exceed 17 or 18 per cent, of the original weight. To obtain the fibrine of a muscle, it must be finely minced and washed in repeated portions of water at 60° or 70°, till all colouring and soluble substances are withdrawn, and till the residue is colourless, insipid, and inodorous; it is then strongly pressed between folds of linen, which renders it semitransparent and pulverulent. Berzelius observes that in this state it becomes so strongly electro-positive when triturated, that the particles repel each other and adhere to the mortar, and that it stil retains fat which is separable by alcohol or ether. When long boiled in water, it shrinks, hardens, and yields a portion of gelatine de- rived from the insterstitial cellular membrane; the fibrine itself is also modified by the con- tinued action of boiling water, and loses its solubility in acetic acid, which, when digested with it in its previous state, forms a gelatinous mass soluble in water, but slightly turbid from the presence of fat and a portion of insoluble membrane, derived apparently from the vessels which pervaded the original muscle. It is soluble in diluted caustic potassa, and precipi- tated by excess of muriatic acid, the precipitate being a compound of fibrine with excess of muriatic acid, and which, when washed with distilled water, becomes gelatinous and soluble, being reduced to the state of a neutral muriate of fibrine.* When the fibrine of muscle is mixed with its weight of sulphuric acid, it swells and dis- solves, and, when gently heated, a little fat rises to the surface and may be separated : if the mass is then diluted with twice its weight of water and boiled for nine hours, (occasion- ally replacing the loss by evaporation,) am- monia is formed, which combines with the acid, and on saturating it with carbonate of lime, filtering, and evaporating to dryness, a yellow residue remains, consisting of three distinct products: two of these are taken up by digestion in boiling alcohol of the specific gravity of .845, and are obtained upon evapo- ration ; this residue, treated with alcohol of the specific gravity of .830, communicates to it (1) a portion of a peculiar extractive matter, and the insoluble remainder (2) is white, soluble in water and crystallisable, and has been called by Braconnot leucine.^ It fuses at 212°, ex- * It will be observed, by reference to the article ALBUMEN, that that principle and fibrine, if not identical, are very closely allied, and appear rather to differ in organization than in essential chemical characters : accordingly the fibrine of the blood may be considered as a modification of seralbumen, and that of muscular fibre as little differing from the fibrine of the blood. t Ann. de Chim. et Phys. xiii. 119. S 2 260 FIBRQ-CARTILAGE. haling the odour of roasted meat, and partly sublimes : it is difficultly soluble in alcohol. It dissolves in nitric acid, and yields on eva- poration a white crystalline compound, the nitro-lcucic acid. The portion of the original residue which is insoluble in alcohol (3) is yellow, and its aqueous solution is precipi- tated by infusion of galls, subacetate of lead, nitrate of mercury, and persulphate of iron. It appears therefore that the products of the action of sulphuric acid upon the fibrine of muscle, are, 1, an extractive matter soluble in alcohol; 2. leucine; and 3. extractive, inso- luble in alcohol but soluble in water. (W. T. Brande.) FIBRO-CARTILAGE, (Cartilago liga- ment osav .fibrosa ; Fr. Tissu fibrocartilagineux ; Germ. Faser-Knorpel oder Band-Knorpel ). — As early as the time of Galen we find certain organs distinguished by the appellation vtv^o- Xov&guh*; cvv§tap.oi, and Fallopius uses a similar term, namely, chondrosyndesmos, as denoting a substance distinct from true carti- lage. Haase* also, who wrote in 1747, speaks of two structures different from true cartilage, under the names of cartilagines ligamentoste and cartilagines mixta. Bichat likewise recog- nised a class of tissues distinct from pure cartilage, and by him it would appear that the name fibro-cartilage was first employed. It is evident that no organ should be classed under the head of fibro-cartilage unless it con- sist distinctly of fibrous tissue and cartilage intermixed, and thus combine not only the structure but the properties of both, the strength and power of resistance of the one, and the elas- ticity of the other; nevertheless, we shall find, in examining the various structures which are admitted by anatomists to be fibro-cartilaginous, that the fibrous tissue predominates in such a manner as to justify Beclard in regarding fibro- cartilage as a portion of the ligamentous struc- ture, which might be designated cartilaginiform ligamentous organs. The distinction was fully admitted too by Mr. Hunter in reference to the texture of the so-called inter-articular car- tilages. Speaking of that of the temporo- maxillary articulation, he says, " its texture is ligamento-cartilaginous."t The classification of fibro-cartilages adopted by Meckel seems to me to be the best; he arranges them under three classes:— 1. Those whose two surfaces are free wholly or at least in great part, and whose edges are united to the synovial capsules, the moveable fibro-car- tilages of articulation. 2. Those which are free by one of their surfaces, and which adhere to bone or tendon by the other : these are the fibro-cartilages of tendinous sheaths, or those which limit the articular cavities, and may be called fibro-cartilages of circumference or cylindrical fibro-cartilages. 3. Those whose two surfaces are adherent in their entire extent to the bones between which they are placed. * De fabrica cartilaginum, Lipsiae, 1747. t Hunter on the Teeth. Of these classes the first and third and some of those which come under the second belong to the articulations. Their forms and structure have already been described in the article Articulation. I may here, however, notice the statement of Weber* in regard to the discs interposed between the vertebrae, which have been generally regarded as fibro-cartilaginous. This anatomist denies that they exhibit any intermixture of cartilaginous substance, and considers that this is rendered manifest by stretching the intervertebral substance, by which it becomes reduced to a fibrous expansion C sehnighautige Masse ) ; he consequently places these intervertebral discs among the fibrous tissues. There can be no doubt that the cir- cumference of each disc is purely fibrous, and that the concentric vertical lamellae of fibrous tissue extend for some distance towards the centre of the disc; but I am at a loss to per- ceive any resemblance to fibrous tissues in the soft and elastic, and yielding substance which forms the centre. It seems to me that this texture can only be regarded as a modified form of cartilage, differing in its want of density from the ordinary cartilage, whether permanent or temporary. The intervertebral substance, however, to whatever texture it may ultimately be decided to belong, does present very striking differences from the other organs which are placed among the fibro-cartilages. It is in the fibro-cartilages of the second class that we see most uniformly the inter- mixture of the fibrous and cartilaginous texture, although here, likewise, the fibrous tissue pre- dominates over the cartilaginous. The fibro-cartilages are remarkable for their great flexibility, in virtue of which they are enabled to resist fracture, and this property is no doubt owing to the intermixture of fibrous tissue; cartilaginous laminae, on the other hand, are easily broken by bending, and many of them exhibit a fibrous appearance on the surface of the fracture, which, however, arises from the irregular fracture and not from the existence of fibres. Fibro-cartilages are of a dull white colour and quite opaque ; they have no perichon- drium, but are either in immediate connexion with bone, being inserted into it by their fibrous burjdles, or are covered by the synovial mem- brane of the joint in which they are enclosed. Their physical and vital properties are those which belong to pure cartilage and to fibrous tissue. Their force of cohesion is very great and surpasses even that of bones. They are more vascular than pure cartilage, but in the natural state they admit very few vessels carry- ing red blood. Bichat examined the fibro- cartilages in an animal which died asphyxiated, and found these organs not injected. The remarkable manner in which fibro-cartilages resist the influence of a compressing tumour, as a pulsating aneurism, is well known; while by such means the bodies of the vertebrae are completely destroyed, the intervertebral discs will remain quite uninjured. * Einige Beobachtungen iiber das Structur der Knorpel und Faser-Knorpel, in Meckel's Archiv for 1827. F1BR0-CARTILAGE. 261 Fibro-cartilages dry readily when exposed to the air and become of a deep yellow colour; they resist for a very long time, many months, the influence of maceration, and by long-con- tinued boiling they become converted into a gelatinous substance. Their chemical compo- sition is said to be made up of albumen, phos- phate of lime, chlorurets of sodium and of potassium, sulphate of lime and other salts, usually found in animal textures. The microscopic characters of fibro-cartilage do not seem to have been investigated with the same care as those of many other textures. I have examined by transmitted light very thin slices of the fibro-cartilages in the knee and temporo-maxillary joint, and the appearance presented was uniformly that of a very compli- cated cellular structure, composed of minute meshes, very irregular in size and shape. In examining the intervertebral substance I have distinctly seen, towards the circumference of the d ise, those fine and uniform cylindrical fibres with wave-like bendings described and figured by Jordan j* but towards the centre the texture exhibited the cellular appearance with larger meshes, similar to that seen in the fibro- cartilages of the knee and joint of the lower jaw.f Of the structures placed by Bichat among the fibro-cartilages, some have been considered by Meckel, Beclard, Weber, and other anato- mists to be pure cartilage, and as it seems to me with much justice. These are the membra- niform cartilages of the external ear, Eustachian tube, nose, larynx, trachea, and eyelids. The cartilaginous nature of most of these textures is very apparent upon carefully dissecting off the dense perichondrium which invests them, and to which, doubtless, they owe their flexi- bility, or more correctly, by which they are prevented from being fractured under the influence of a bending force. Careful micro- scopic observation may assist materially in affording marks indicative of pure cartilage ; and as the observations of Purkinje, Miiller, and Miescher approach in some degree to this object, I have thought it not foreign to the subject of this article to introduce here some account of these researches. The results of Purkinje's examinations of the minute structure of bone as well as cartilage were published in the year 1834 in an inaugural dissertation by Deutsch.I Miiller and Miescher have further investigated the subject and confirmed the statements of Purkinje.§ In examining thin slices of cartilage under * Uber das Gewebe der Tunica Dartos, &c. Muller's Archiv, 1834. + Miescher states that in infants this part of the intervertebral substance is composed of a pellucid mucus, which, under the microscope, sometimes exhibits some of the cartilaginous corpuscles to be noticed in a subsequent part of this article, but in adults it is composed of adipose tissue! t De penitiori ossium structura. Diss, inaug. Vratisl. 1834. § Vid. Miiller, Vergleichende Anatomic der Myxinoiden, Berlin, 1835, and Miescher, de ossium genes, structura, et vita. Diss, inaug. Berol. 1836. b Fie. 139. the microscope by transmitted light, Purkinje observed numerous little bodies irregularly dis- persed through its texture, of a round or oval form, and somewhat less transparent than the intervening substance. The annexed figure, taken from Miiller's work already referred to, gives a representation of these bodies : they are deno- minated by Purkinje cartilaginous corpuscles (Knorpel Korperchen). In some cases, as in tem- porary cartilage, they ap^ peared to consist of mi- nute granules ; they pre- sented this appearance likewise in the cartilagi- nous part of the cranium of a frog. In the costal cartilages they were solid, and in the cartilaginous fishes, as in the lamprey, their contents were of a soft or fluid consistence. According to Purkinje, these corpuscles are found in the temporary cartilages, in permanent cartilage, in cartilage which becomes ossified in old age, as that of the ribs and larynx, in the cartilages of the nose and septum narium. According to Miescher there are two kinds of permanent cartilage, differing from each other as well by external characters as by in- ternal structure ; one of these scarcely differs at all from the temporary cartilage, the other is very dissimilar in structure. The first class is at once distinguished by its azure whiteness and by its pellucid brightness, not unlike that of mother-of-pearl, from the second, which is yellowish in colour, not pellucid, and spongy in texture. To the former class belong all articular cartilages, those of the ribs,* that of the ensiform cartilage of the sternum, the thy- roid, cricoid, and arytenoid cartilages, and those of the septum narium and aire nasi. All the cartilages of this class are characterized by containing the microscopic corpuscles above described, variously arranged in each form of cartilage, in some placed in clusters, in others closely aggregated together in one part and separated in another. It is interesting to ob- serve that the temporary cartilage universally contains these corpuscles, and as all the carti- lages we have described are more or less prone to ossification in advanced age, we are led to the inference, that these corpuscles thus de- posited are characteristic of cartilage which admits of becoming ossified.f * Sic Miescher. t The cartilages most liable to ossify by the pro- gress of age in man, are those which most fre- quently exhibit, after a certain period, a per- manently ossified condition in some of the inferior classes of animals. Thus, in birds, and among mammals, in monotremata, cheiroptera, and cetacca, the cartilages of the ribs show a very early dis- position to ossify. In birds the laryngeal cartilages are very apt to ossify, and in swine and oxen par tial ossifications of the same cartilages are not 262 FIBRO-CARTILAGE. To the second class of cartilages belong those of the external ear, of the epiglottis, and the capitula of Santo rini, connected with the apices of the arytenoid cartilages, which in the ruminants, the hog tribe, and others, are of con- siderable size. Besides the characters already mentioned which distinguish this class of car- tilage from the former, the microscope dis- closes some further differences. " Placed under the microscope," says Miescher, " the cartilages of this class present a very delicate network, opaque, composed of small round meshes which are filled by a uniform, pellucid substance, and each generally contains a single corpuscle somewhat roundish or oblong." The cartilages that belong to this class are con- trasted with those of the former, as being never transformed into bone. I may add, that in my own examinations of pure cartilage, from the skeletons of cartila- ginous fishes, and from the human subject, I have found the foregoing descriptions correct. The cartilaginous corpuscles may be always seen under the compound microscope, with an object glass of a quarter of an inch or an eighth of an inch focus. In man and the mammalia, the following structures may be enumerated as belonging to the class of fibro-cartilages: 1. The so-called inter-articular cartilages in the knee, sterno- clavicular, and temporo-maxillary joints ; that in the wrist-joint seems to me to be purely cartilaginous. 2. The fibro-cartilages of cir- cumference, as in the hip and shoulder-joints. 3. The fibro-cartilages of tendons, which ulti- timately form sesamoid bones, and those of tendinous sheaths. 4. According to Miescher, the tarsal cartilages. 5. The inter-osseous lamina;, as those between the pubes, pieces of the sacrum and coccyx, and, in a modified form, the intervertebral substance. In the inferior vertebrata and in the inver- tebrata fibro-cartilage gradually disappears : in the former, the intervertebral substance seems to be the only remnant of it, excepting perhaps the sclerotic coat of the eye in some fishes. In the invertebrata, Blainville considers the three tubercular teeth of the leech as being fibro-cartilaginous. Morbid conditions of fibro-cartilage. — As fibro-cartilage in its physical and vital pro- perties so nearly approaches pure cartilage, it is reasonable to expect a great similarity in the phenomena of disease as they are manifested in the two tissues. Fibro-cartilage appears to be susceptible of reparation in the same man- ner as pure cartilage. (See Cartilage.) A substance bearing some resemblance to fibro- cartilage sometimes forms the connecting me- dium between the fractured portions of a bone, where bony union cannot be obtained. The phenomena of inflammation and ulce- ration in fibro-cartilages are very similar to unfrequently found. Ossification of the nasal cartilages is extremely rave, but in the hog tribe two bones extend from ihe intermaxillary bone into the cartilage of the proboscis. — Vide Miescher, )oc. cit. p, 27. those in pure cartilage : in the joints these morbid changes are generally complicated with similar diseased conditions of the other tex- tures, either cartilages or bones, whence they are propagated to the fibro-cartilages. It is well known that a condition of the interverte- bral discs, which is commonly spoken of under the name of ulceration, is frequently coin- cident with caries of the vertebrae, having in some instances preceded the vertebral disease, and in others followed it. To Sir Benjamin Brodie we are indebted for the observation that the diseased state of the intervertebral substance has sometimes the precedence of that of the bones ; in one case, related by him, where ulceration of the articular cartilages had begun in several other parts, those between the bodies of some of the dorsal vertebrae were found to have been very much altered from their natural structure. He adds, " I had an opportunity of noticing a similar morbid condition of two of the intervertebral cartilages in a patient who, some time after having received a blow on the loins, was affected with such symptoms as in- duced Mr. Keate to consider this case as one of incipient caries of the spine, and to treat it, accordingly, with caustic issues ; and who under these circumstances died of another complaint. Opportunities of examining the morbid appearances in this very early stage of disease in the spine are of very rare occur- rence, but they are sufficiently frequent when the disease has made a greater progress; and in such cases I have, in some instances, found the intervertebral cartilages in a state of ulce- ration while the bones were either in a perfectly healthy state, or merely affected with chronic inflammation, without having lost their natural texture and hardness."* Otto mentions that he has several times satisfied himself that the destruction of the spine may originally spring from the intervertebral substance; but he has never found suppuration, unless when at the same time the bones and neighbouring cellular tissue were inflamed.+ The anatomical cha- racters of this condition to which we have been alluding consist in an erosion and soften- ing of the fibro-cartilage, frequently attended with the effusion on the surface of a dirty puriform and often fetid fluid. Fibro-cartilage is not prone to become ossi- fied; in very old subjects the superficial portion of the intervertebral substances is often ossi- fied, but this is an extension of ossification from the bone or from the anterior common ligament : it is very rare to find any of the inter-articular fibro-cartilages ossified. The ossification of the interpubic fibro-cartilage in advanced age seems to be of a similar nature to that of the intervertebral substances. Masses of a substance very similar to fibro- cartilage are sometimes met with accidentally developed ; we find them in or connected with the uterus, in tumours, and in serous or sy-» novial membranes. (R. B. Todd.) * Brodie on the Joints, edit. 2d, p. 231, t Pathol. Anat. by South. FIBROUS TISSUE. 263' FIBROUS TISSUE * tela fibrosa, vel ten- dinea ; Germ, das sehnige Gewebe. The parts comprised in the fibrous system may with propriety be referred to two separate and distinct classes. I. White fibrous organs. — Under this head the following structures, distinguished by their whitish colour, their fibrous organization, and their great power of resistance, are in- cluded : — a, the periosteum and perichondrium ; b, fasciae or muscular aponeuroses ; c, sheaths of the tendons ; d, fibrous coverings of certain organs ; e, ligaments ; j\ tendons. II. Yellow elastic fibrous organs. — There are certain organs, ex. gr. the yellow ligaments ( ligumenta subflava ) of the spine, which resemble those of the former class by their fibrous structure, but which present so many important peculiarities in their texture and properties, that it is necessary to consider them apart from the preceding. All these organs resemble each other by possessing more or less a yellow colour, and a remarkable de- gree of elasticity. I. White fibrous organs. — Organiza- tion. This consists of a union of white or grayish fibres more or less distinct accord- ing to the part in which they are examined ; thus they are very apparent in most of the ligaments, in the fascia, in the periosteum, and in many tendons, as in those of the obliquus abdominis externus, pectoralis major, &c. In other structures, on the contrary, as in the greater number of tendons, the fibres are so small and so closely united that they cannot be perceived but with difficulty, although they be- come more evident on maceration. In most parts of the body they observe a parallel direc- tion, whilst in other places they pass in an irre- gular manner, so as to cross and interlace with each other, occasionally constituting, as in the instance of the dura mater and of the tendinous centre of the diaphragm, a very intricate net- work of fibres. The result of a careful examination proves that the remarkably firm and resisting threads which constitute the basis of the various fibrous organs, are composed of condensed cellular tissue. In certain regions we may perceive the gradual transformation of the cellular tissue into a fibrous organ, as in the formation of the superficial fascia of the abdomen ; whilst by prolonged maceration the most dense tendon or ligament may be reduced into a pulpy cellu- lar substance : this opinion is corroborated by Isenflamm, who conceives that this tissue is formed by cellular fibres impregnated with gluten and albumen ; and also by Beclard, who regards it as being composed of cellular texture very much condensed. We may therefore conclude that the ideas of Professor Chaussier, * The expression fibrous tissue is by no means well chosen, as it is equally applicable to other and dissimilar organs, such as muscles, nerves, &c. all of which are eminently distinguished by a fibrous structure. It is, however, preferable to retain a received though inaccurate term, than to add to that multitude of names which already so much encumbers the science of anatomy. as to the existence of an elementary organic solid, called by him the albugineous fibre, and which is supposed to form the basis of all the ligamentous and tendinous parts of the body, are erroneous. The individual fibres are surrounded by pro- cesses of a more lax membrane, which pene- trates between them, and which is rendered particularly apparent by maceration and in cer- tain diseases. The differences that are observed in contrasting the various fibrous organs with each other, a ligament for example with a ten- don, seem principally to result from the larger or smaller proportion of the interfibrous cellu- lar substance and on the degree of its conden- sation. This combination of the common cel- lular tissue with the ligamentous fibres allows the fibrous organs to yield in a very slight de- gree when extended by the elasticity which is thus bestowed, and also slightly to contract on themselves on the removal of the extending force. Bloodvessels. — The proper fibrous tissue re- ceives but a small quantity of blood, the arteries being minute in size, and principally carrying a colourless fluid. The great vascularity of the dura m;iter and periosteum is no exception to this remark, because the vessels of these membranes are not proper to them, but to the veins they cover. Absorbents. — The ravages of disease in the neighbourhood of joints, involving the liga- ments in ulceration ; the sloughing of tendons, the destruction of the periosteum by the pres- sure of aneurism, of the tunica albuginea in scrofulous or malignant fungus of the testis, are abundant proofs of the existence of absor- bent vessels. Nerves. — According to Monro, nervous fila- ments may be traced to some of the fibrous organs ; and other anatomists, Cruveilhier for instance, speak of nerves being furnished to the joints; in general, however, none are to be seen ; but as sensibility becomes developed in disease, we must presume that communications do exist with the encephalon. Chemical properties. — The principal sub- stances that have been detected in the fibrous as in the cellular tissue consist of coagulated albumen and gelatine ; a small quantity of mucus and saline matter has also been disco- vered. The effects of desiccation are well known, tendons and ligaments becoming hard, transparent, yellowish, and fragile. This tissue resists maceration for a long time, but at length it is rendered soft and flocculent, so that the fibres can be separated and unravelled ; ulti- mately it is converted into a pulpy and fila- mentous cellular mass. Properties. — The offices which these organs are designed to fulfil in the economy being, with the exception of the periosteum and its analogous membrane the dura mater, of a me- chanical character, the properties by which they are distinguished are almost entirely of a physical nature. They offer great resistance to rupture, and thus the ligaments are capable of opposing the shocks to which, in the violent movements of the joints, they are so frequently 264 FIBROUS TISSUE. exposed ; whilst the same cohesive property enables the tendons, under all ordinary circum- stances, to bear the immense force of muscular contraction. Having considered the general characters of these organs, I shall proceed to describe the most essential properties of each individual class. 1. Of the periosteum. — This may be regard- ed as the most important of the fibrous tissues ; indeed so universal are its connexions, that if any common centre of this system were sought for, we should certainly coincide with Bichat in considering this to be the periosteum. Dis- carding the erroneous ideas of the ancients and Arabian physicians, who imagined that the membranes of the body were all continued from those of the head, we shall find that, with the exception of the perichondrium of the larynx and the fibrous tunics of some glandular bodies, all the fibrous organs are in connexion with the periosteum. The inner surface of the periosteum firmly adheres to the several bones by a multitude of delicate processes passing into the openings observed on their external surface. These pro- cesses convey into the bones an amazing num- ber of fine arteries and veins, called therefore periosteal, and which may be regarded as the principal, or as some anatomists contend, the only proper vessels of the osseous tissue. The outer surface is rough, and is united by the cellular tissue to the surrounding muscles, tendons, ligaments, and fascia? ; in the nostrils, sinuses, and tympanum, the periosteum is, however, joined to the mucous membranes, and in the skull the surface unattached to the bones is lined by the arachnoid. The periosteum constitutes the nutrient membrane of the bones, and thus bears an im- portant part in the process of ossification and in the reparation of fractured and diseased bones ; it also serves as a medium for the attachment of the ligaments, tendons, and fascia? to the skeleton. 2. Fascia. — The fibrous fasciae or aponeu- roses not only invest the surface of the limbs, but also furnish a number of processes, which, penetrating deeply among the several muscles, form sheaths to those organs, by which they as well as the bloodvessels and nerves are main- tained in their proper situation. It is evident that these partitions must exert a great influence on the growth of various kinds of tumours, on effusion of blood, on the extravasation of urine, and on the formation of matter; so that their relations form an important branch of surgical anatomy. In order to give to these muscular envelopes the necessary degree of tension, they are either provided with special muscles, as in the case of the tensor vagina? femoris and the palmaris longus, or they receive processes from the neighbouring tendons, as from the biceps cubiti, semi-tendinosus, and so forth. The aponeuroses thus braced afford a firm support to the parts they cover, and in this manner they increase the powers of the muscu- lar system ; whilst by their resistance they efficiently protect the vessels and nerves from external violence, and at the same time proba- bly assist in the circulation of the blood and lymph, and so prevent varicose enlargement of the deep-seated veins and oedema of the extre- mities. See Fascia. 3. Tendinous sheaths.— These are in their office analogous with the last, excepting that, instead of fixing the muscles, they secure the tendons during muscular action. The thecal ligaments of the hand and foot, the annular ligaments of the wrist and ankle, and the fascial sheaths around the knee are of this character. They are distinguished by their great strength, and as they are internally lined by synovial membrane, they facilitate the play of the ten- dons ; and in many instances, as in the trochlea of the os frontis and the sulci of the carpal extre- mity of the radius, they also modify the action of the muscles whose tendons they transmit. 4. Fibrous coverings.- — -Certain organs are provided, for the purpose of protection, with dense ligamentous coverings ; of this order are the dura mater, the sclerotic coat of the eye, the loose portion of the pericardium, the proper covering of the kidney, of the salivary glands, mamma, spleen, thyroid gland, thymus, lym- phatic glands, of the prostate, testicle and ovary ; probably the exterior investment of the nervous ganglia is of the same character. Some of these envelopes, as the dura mater, pericar- dium, and tunica albuginea testis, are lined on one surface by a serous membrane, and thus constitute Jibro-serous membranes, or as they are called by Beclard, compound fibrous mem- branes. 5. Ligaments. — These bodies possess in an eminent degree those properties by which the whole fibrous system is distinguished ; and consequently the term ligamentous is often em- ployed to designate the whole of the fibrous organs. The ligaments fulfil a very important office in the animal economy by binding together the various bones of the skeleton, an object which they are enabled to effect in consequence of their fibres being very firmly attached, and as it were consolidated with the osseous system through the medium of the periosteum. It is stated by Portal, that after the bones have been softened by the influence of an acid, the liga- ments are observed to send processes into their substance, which cause the ligaments to adhere so firmly that, although by very great force they may be torn, yet they cannot be separated from the bones. Although these organs are dissimilar in shape, yet there are three forms among them which predominate: t. the capsular, 2. the funicular, 3. what, for want of a better ex- pression, may be called laminated. The true fibrous capsules which consist of cylindrical bags lined internally by synovial membrane, are confined to the shoulder and hip-joints, although imperfect capsules exist in many other articulations. The funicular and la- minated ligaments are much more universally diffused, assisting in fact in the formation of every joint in the skeleton. FIBROUS TISSUE. 6. Tendons. — These organs, which serve to connect the muscles to the osseous system, are composed of fibres so closely disposed that some anatomists, but erroneously, doubt their identity with the other fibrous organs. This compactness is owing to the extreme con- densation of the intervening cellular tissue, which is also the cause of these bodies re- sisting for a longer period than the ligamen- tous or fascial structures, the influence of ma- ceration. Every tendon is united by one of its ex- tremities to the fibres of the muscle to which it belongs, and by the other it is connected with the bone or other part on which the muscle is destined to act. The exact mode of connexion between the tendinous and mus- cular tissues is difficult to determine. Ocular and microscopical inspection seem to prove that the tendinous fibres result from the con- tinuation and condensation of those cellular sheaths, which inclose and in part form the muscular fibrils. It has, however, been stated that there is an intermediate substance between the muscle and the tendon, different from both of them, and serving to connect them together. The details relative to the mecha- nical disposition of these organs belong to the consideration of the muscular system. — See Muscle. II. Yellow elastic fibrous organs. — (Tela elastica.) It was justly observed by Bichat that the ligaments placed between the arches of the vertebrae differ in their nature from the other ligaments of the body; and modern anatomists, admitting this distinction, have enumerated the following structures as a separate class of the fibrous organs : the yellow ligaments of the spine ; the external and espe- cially the middle or proper membrane of the arteries, the fibrous covering of the excretory ducts; the ligamentous tissue joining the carti- lages of the air-passages; the fibrous envelope of the cavernous bodies of the penis and clitoris, and of the vesiculas seminales. Although the highest authorities consider that the middle tunic of the arteries is com- posed of this tissue, yet the correctness of this opinion is very doubtful. It is true that, as far as colour is concerned, the similarity is well founded ; but the arterial fibrous coat is endowed with a power of contraction, evi- dently distinct from mere elastic contraction, which is totally wanting in the true yellow fibrous tissue. In addition to the parts above named, it is necessary to add that in certain organs where great elasticity is requisite there is a peculiar yellow cellular substance, which, although it does not present the dense and fibrous cha- racter, appears to belong essentially to the organs under consideration. This texture is particularly distinct in the mucous folds which constitute the superior boundary of the glottis, a part that is remarkable for its extra- ordinary elasticity.* * It is slated by Sir E. Home (Lett, on Comp. Anat. vol. ii. p. 49,) that this tissue enters into the It occasionally happens, as in the forma- tion of the intervertebral substance, that the yellow fibrous tissue and the common liga- mentous are combined. A more striking instance of this combination is seen in the construction of the connecting ligament which forms the hinge in bivalve shells, in which one part, the external, is composed of ligamentous matter, whilst another, the internal, consists of a highly elastic fibrous tissue. Organization and properties. — If the yellow ligament of the spine or the ligamentum nu- chas in ruminants be examined, it will be seen that each is smooth on its surface, and is made up of a great number of longitudinal and highly elastic fibres, which, in the latter in- stance, are readily separated and unravelled by the finger. This texture is, I believe, sui generis, and is altogether distinct from the common ligamentous structures. In a recent publication,* M. Laurent conceives that this tissue is intermediate in its characters to the tissus scltreux (under which term he proposes to class the white fibrous organs, the cartilages and bones,) and the muscular tissue ; he there- fore calls it tissu sclero-sarceux. Although it is very doubtful if the elastic fibrous structures have any thing in their organization similar to the muscular fibre, yet it is certain that in function they are intermediate between the common ligaments and the muscles, a fact which is kept in view in thellunterian Museum, in which the elastic ligaments are placed next to the muscles. The resistance and elasticity of these organs enable them firmly to connect together the parts to which they are attached, and at the same time allow them to yield to double their length on the application of an extending force. In this manner they economise mus- cular action, by substituting for that force the power of elasticity. This employment of an elastic rather than a muscular power is evinced in the yellow ligaments of the spine, which pull the vertebras towards each other, and thus assist the muscles in maintaining the upright posture. The same thing is also seen in many of the lower ani- mals ; as in the support of the head by the ligamentum nuchas — the retraction of the claws in the feline carnivora by an elastic ligament — and the support of the abdominal organs in many large quadrupeds by the elastic super- ficial fascia. But the most interesting ex- ample of this economy of muscular action is displayed in the bivalve shell of the oyster and other acephalous mollusca, in which in- stance not only is the shell kept open by the elastic ligament of the hinge for the purpose of admitting the nutriment of the animal ; but formation of muscle ; but this is probably erro- neous, as the elasticity of muscles depends on the large proportion of elastic cellular membrane w hich they contain. Lobstein has also published some observations in the Jour. Univer. des Sc. Med. on the tissue of the uterus, which he regards as ana- logous to the so-called yellow tissue of the middle arterial coat. * Annales Franchises el Eu-angcres d'Anal. et dc Physiol. Jan. 1837. I*. 59. 266 FIBROUS TISSUE. as the valves are designed by nature to be separated only to a limited extent, an elastic ligamentous structure is placed between them towards their centre, and in this manner all undue separation is prevented without any demand being made on the force of the ad- ductor muscle.* Morbid anatomy. I. Inflammation. — The low degree of organization possessed by this tissue modifies the inflammatory process, which is usually chronic in its nature, and often extremely insidious in its progress ; occa- sionally, however, as in sprains, acute rheu- matism, &c, the fibrous organs are the seat of very active disease. Owing to their great density, but little swelling takes place unless there be chronic and prolonged inflammation ; in which case, as is particularly observed in disease of the joints, a quantity of jelly-like fluid is poured into the interstitial cellular tissue, the proper fibres become massed toge- ther and with the surrounding parts, till in the advanced stage all traces of the original for- mation being lost in the diseased mass, it be- comes reduced to the pulpy consistence of diseased cellular membrane, of which the healthy structure is a modification. This deposit and thickening are the most common products of inflammation in liga- mentous parts ; but it occasionally happens that a true abscess is formed, as when pus is thrown out between the dura mater and cra- nium. I have known one case connected with disease of the bone, in which matter was de- posited in the substance of the dura mater, and in which the operation of trephining was ultimately required for the relief of the patient. Ulceration is a frequent result of scrophu- lous disease of the joints, causing great ravages in the ligaments and neighbouring parts. Mortification of ligament is not a common occurrence, whilst in the acute inflammation of tendon, especially in neglected thecal ab- scess, and of fascia in consequence of large abscess under it, sloughing is not unfrequently witnessed. There are of course certain modifications in the effects of inflammation according to the part attacked. Thus, in ligament, there is a great tendency to ulceration ; in tendon to mortification ; in the periosteum to great in- duration ; and, as we see in the formation of a node and of callus, to a transformation into cartilage and even bone. When fascia is the seat of disease, the consolidation arising from effusion often gives rise to a retraction of the affected part; a result which has been observed, for example, in inflammation of the aponeu- * Leach, Bullet, des Sciences, 1818. P. 14. [Mr. Hunter fully recognised the value of this elastic tissue, and in his Museum he set apart a series for its illustration under two classes — 1st, as an antagonist to muscle, and 2d, in aid of mus- cular action. In the former class he places such examples as that of the oyster alluded to in the text, in the latter the ligamenta nuchae and the elastic fibrous expansion on the abdomen of the elephant and other larger quadrupeds. See the Descriptive and Illustrated Catalogue of the Hun- terian Museum, vol. i. — Ed.] rosis of the fore-arm, and in that affection of the palmar fascia called by Boyer and other writers crispatura tendinum* II. Cartilaginous transformation and ossi- fication.— Many parts of the fibrous system not unfrequently become cartilaginous or even osseous. The cartilaginous transformation is often observed in the ligaments of diseased and anchylosed joints; in the periosteum after fractures and in the formation of nodes ; in tendons, especially those which are exposed to great friction in the fibrous covering of the spleen. I have had opportunities of seeing many specimens of cartilaginous deposit taking place between the periosteum and the bone, and evidently arising from the former. The valuable collection of my friend Mr. Listen contains a very fine specimen of a large carti- laginous tumour proceeding from the peri- osteum. Ossification, although extremely common, occurs much more frequently in some than in other classes of these organs : thus it is often met with in the dura mater, in which structure, as far as I have observed, the bony excres- cence always proceeds from the inner layer or that towards the arachnoid, and consequently presses against the brain. In one very re- markable specimen in my possession, nearly the whole of the falx, and a large extent of the membrane attached to the vault of the cranium, are completely ossified. In an instance, ob- served I believe by Dr. Barlow (Southwark), the heart was completely encased in bone, owing to the entire ossification of the peri- cardium. The cicatrix of a wounded tendon is often osseous. III. Fungus. — The dura mater, the peri- osteum, the fascia, &c, are subject to excres- cences having a fungoid appearance, which vary in their nature, often consisting of a chronic, indolent growth, whilst at other times they are evidently scrophulous, and occasion- ally they are malignant. In the progress of those cases where the disease is situated near the bones, these organs are implicated, and some doubt has conse- quently arisen concerning the first seat of the disease ; it is, however, proved by examination that in the fungus of the dura mater and other fibrous parts, the bones are only secondarily affected. A good illustration of this fact is afforded by a preparation consisting of an extensive fungus arising from the periosteum covering the tibia, in which it is evident, al- * Boyer, Traite des Malad. Chir. torn. v. p. 55. This peculiar affection was some years since pointed out by Sir A. Cooper, and has since been more fully described by Baron Dupuytren, (Lecons Orales de Chir. Clin. torn. i. p. 2). The tension and contrac- tion of the palmar fascia, which are usually caused by continued pressure, give rise to aretraction of one or more of the fingers, and may be removed by transversely and freely dividing the aponeurosis opposite to the metacarpo phalangean joint. I have known one case of similar induration of the fibrous sheath of the corpus cavcrnosum penis ; and I have learnt from Sir A. Cooper that he has seen several such cases, occurring in persons who had freely indulged in sexual intercourse. Boyer has made a similar observation. FIBULAR ARTERY. 267 though the subjacent bone has been partly absorbed, that the fungoid disease entirely originated from the periosteum* Malignant fungus occasionally arises from the periosteum. I have seen one case of this disease connected with the tibia, in which amputation was performed, but with an un- favourable result, the patient sinking rapidly from mortification. In medullary sarcoma that membrane is often involved. Osteo - sarcoma, according to Ilowship, Craigie, and Meckel, occasionally has its ori- gin in the periosteum. ( R. D. Grainger. ) FIBULAR ARTERY, (art'eria peronaa ; Fr. artire peroniere ; Germ, die Wudenbein- urterie ). — This artery is commonly described as a branch of the posterior tibial, or it may be said to be one of the branches resulting from the bifurcation of a short trunk which has its origin immediately from the popliteal, and which has been described under the name of the tibio-peroneal artery, the other branch of the bifurcation being what is ordinarily considered as the continued posterior tibial trunk. The origin of the fibular artery is situated about an inch below the inferior margin of the popliteus muscle, thence the artery extends downwards and with a very gradual inclination outwards, and terminates in the region of the external ankle, just above the os calcis and behind the fibula. It is a vessel of smaller size than the posterior tibial, and about equal to the anterior tibial, and it is interesting to ob- serve that the varieties in its calibre are in the inverse ratio of the calibre of the anterior and posterior tibial, but more especially of the former. To expose the fibular artery in dissection the gastrocnemius and soleus muscles must be raised, and the deep fascia of the leg dissected away. The artery is then seen resting at first for a very short distance upon the tibialis posti- cus muscle, and from it getting upon the pos- terior surface of the fibula near its tibial edge, where the vessel is imbedded in the flexor pol- licis proprius and encased between that muscle and the bone. Inferiorly it passes between the flexor pollicis proprius and tibialis posticus, and is applied to the posterior surface of the interosseous ligament. The fibular artery is sometimes altogether absent, and then its place is supplied by rami- fications of the posterior tibial. Sometimes the fibular artery takes its rise higher up than the point we have indicated ; but more frequently it has a lower origin, in which case it presents a calibre smaller than that which may be con- sidered as usual ; the vessel, indeed, is found to be smaller the lower down its origin is. It is in these cases that the anterior tibial especially and the posterior tibial occur of a larger size than The result of dissection induces me to suppose that in many old and intractable ulceis, the fun- goid excrescences seen on the surface arise either from the fascia of the leg or from the periosteum, according as they are placed on the outer or inner part of the limb. natural, as it were to compensate for the de- ficiency of the fibular. Branches.- — The first branches the fibular artery gives off are small muscular ones on either side to the soleus, tibialis posticus, flexor pollicis proprius, to which in its whole course it gives a liberal supply; also to the fibula and the peroncei muscles. From its inner side, according to Cruveilhier, it gives an anasto- motic branch to the posterior tibial, which passes transversely or obliquely from one artery to the other. This branch sometimes attains a considerable size, and in such cases after its communication with the posterior tibial, that artery also becomes considerably enlarged. The fibular artery divides into its two termi- nal arteries in the inferior third of the leg; these are the anterior and posterior peroneal arteries. Anterior peroneal artery, (urteria peronaa anterior and perjorans peronaa.) This branch gains the anterior surface of the leg by piercing the interosseous ligament, where it is covered by the peronaeus tertius muscle. The situation at which this perforation takes place is stated by Harrison to be about two inches above the external ankle; it then inclines downwards upon the outer side of the tibia, anastomoses by a transverse branch with the anti-tibial, com- municates with the external malleolar artery from the anterior tibial, giving off numerous branches both before and after the anastomosis, which pass down to the tarsus and communi- cate with the tarsal arteries. This artery is generally smaller than the posterior, some- times so small that the ordinary injection fails to penetrate it. If there be any anomaly in the size of the anterior tibial artery, this branch is generally large in proportion as that artery is small, and in such a case it might exceed the posterior peroneal in calibre. The arteries of the dorsum of the foot spring from the anterior peroneal when the anterior tibial exhibits this deficiency. Posterior peroneal artery, {A. peronaa pos- terior ; calcanienne externe, Cruveilhier). This branch continues the course of the fibular artery behind the external malleolus to the outer side of the os calcis; it runs parallel to the outer edge of the tendo Achillis, being immediately covered by the continuation of the fascia of the leg. A transverse branch from the inner side of this artery establishes its communication with the posterior tibial, and inferiorly it distributes its terminal branches to the muscles and other parts on the outside of the os calcis to anasto- mose with the external tarsal and plantar arteries; some small vessels proceed round the tendo Achillis to effect a further communication with the posterior tibial. This may be considered as the terminal branch of the fibular artery ; it is absent only when the fibular artery passes entirely forwards, or vi hen it directly opens into the posterior tibial without having any further communica- tion with the arteries of the ankle. The fibular artery is evidently a valuable anastomotic trunk to both the tibial arteries, a deficiency in either of which it is prepared to 268 FIFTH PAIR OF NERVES. supply. Deriving its origin from the same source, and anastomosing freely with both in all parts of their respective courses, it is pre- pared to take the place of either, one might say, at a moment's warning, and the freedom of this communication affords a sufficient indica- tion to surgeons how ineffectual in cases of wounds a single ligature would be; in short, here as in other places where arterial communi- cations are so free, the rule of practice is so clearly pointed out by the anatomy as almost to render it superfluous to appeal to experience. The relations of this artery to operations being very similar to those of the posterior tibial, we refer on this head to the article Tibial Ar- teries. (R. B. Todd.) FIFTH PAIR OF NERVES.— This title is derived from the relation which the nerve bears numerically to the other encephalic pairs; it is the fifth nerve met with on the base of the brain counting from before backwards. The fifth is also called the trigeminal (Winslow) and the trifacial (Chaussier) nerve. It is the nerve upon which the general and tactile sensi- bility of the face and its cavities, as well as the voluntary power of certain muscles of these parts, depends. The following account of this nerve is meant to apply especially to the human subject; but as a knowledge of its structure and distribution in other animals must contribute very much to enlighten us in regard to its true character and properties in man, occasion has been taken to mention those particulars by which it is dis- tinguished throughout the animal series. The fifth nerve is connected at its one ex- tremity with the medulla oblongata, whilst its other end is distributed to the eye and its appendages, to the nostrils, to the palate, the mouth and tongue, to the salivary glands, to the ear, to the integuments and muscles of the face, forehead, and temple, and to the muscles which move the lower jaw in mas- tication, the temporal, pterygoid, and mas- seter muscles. The general distribution of the nerve throughout the animal series corres- ponds to that in man ; but, in certain animals and classes, varieties are presented, which claim our attention equally, whether as matters of curiosity or of physiological interest. In some individuals of the class Mammalia, the eyes possess a very inferior degree of develop- ment; a distinct optic nerve either does not exist or its existence is a matter of doubt, and its place is supplied, in part or alto- gether, by a branch of the second division of the fifth nerve: thus, in the Mole, accord- ing to M. Serres,* the optic is altogether absent, and its place is supplied by a branch of the fifth ; but, according to Treviranus,f that animal is provided with an optic nerve, as large as a human hair, and according to CarusJ it joins an optic branch from the fifth, and the two concur to form the retina. In * Anatomie Comparce du Cerveau, &c. t Journal Complementaire. | Journal Compl. other animals of the same class the optic seems decidedly absent, and its place is supplied al- together by the fifth. Among Reptiles also in- stances occur, in which the optic nerve is wanting. According to both Tie viranus* and Serres, f the fifth nerve takes the place of the optic in the Proteus Anguinus. A va- riety in distribution, still more remarkable, is presented in the disposition of the fifth nerve in Fishes. Among the Rays the audi- tory appears to be, not a distinct nerve, but a branch of the fifth : J the special organs, with which they are provided, likewise, in many instances, derive their nerves from the fifth pair; thus, in some the electrical § organs are supplied by that nerve, and also the albu- mino-gelatinous organs : lastly, in many the nerve is distributed || in a manner and to an extent for which there is no analogy among other animals, the fins being throughout fur- nished with branches from the fifth. Hence in Fish, in which the distribution of the nerve is so much more extended than in other animals, both the size of it is propor- tionally greater, and it consists of a greater^ number of divisions ; these, which in the three other classes of vertebrate animals are only three, amounting with them to from three to six. See sketch of nerves in the Ray and Cod. (Figs. 144, 145.) The size of the fifth nerve is very great, it being by far the largest of those proceeding from the medulla oblongata. In this respect it pre- sents much variety according to the animal or its class. M. Serres states that, the nerves being proportioned always to the volume of the organs from whence they proceed, the extent of the face and of the organs of the senses taken together gives the size of this nerve in the different classes of vertebrate animals. Among the Mammalia the extent of the face and of the organs of the senses increases pro- gressively from Man to Apes, the Carnivora, the Ruminantia, and the Rodentia, and, ac- cording to him, the size of the fifth nerves follows in a general manner the same pro- gression. Birds are remarkable for the atrophy of the muscles of the face and of several of the organs of the senses, and their fifth nerve is far from presenting the developement to be observed in the inferior Mammalia. Reptiles are still lower than Birds with regard to the dimensions of the nerves of the fifth pair; while in Fish** the size of the nerve is very great, and even surpasses in some the volume it presents in the other classes.ft However just the estimate of the comparative volume of the nerve in different animals, as here stated, may * Op. cit. t Op. cit. j Dusmoulins, Journal de Physiologie, t. li. Serres, op. cit. § Desmoulins, Anatomie des Systemes Nerveux, &c. Carus, Rudolphi. || Desmoulins, op. cit. If Desmoulins, op. cit. ** See Sketches of Nerve in the Ray and Cod, Jigs. 144, 145. ' ft Serres, Anatomic Comparce du Cerveau, dans les quatre classes des Animaux. Vertebres. FIFTH PAIR OF NERVES. 209 be, the data, from which it is professedly drawn, may be reasonably objected to. In the first place the volume of the organ cannot be assumed as being alone the measure of that of the nerve supplying it • the degree of ner- vous endowment, whether general or special, which the organ enjoys, must be also taken into account ; and in the second, the extent of the organs of the senses cannot be admitted as a measure of the volume of the fifth nerve, which is not connected with them all ; thus the greater part of the organs of touch is inde- pendent of that nerve. It appears to me that the extent of distribution and amount of endowment conjointly determine the volume of the nerve, and that the latter cannot be inferred a priori. Each nerve is composed of two portions, which are remarkable for particular characters, and have received distinct names; they differ from each other in size, in anatomical disposi- tion, and in function ; one of them, larger than the other, is provided with a ganglion, and dif- fers in its distribution ; it also differs in proper- ties, being subservient to sensation ; the other is small, has no ganglion, and is destined to volition ; they are hence denominated, the former the larger, the ganglionic or the sentient portion, the latter the smaller, the non-ganglio- nic or the voluntary portion. The distinction of the nerve into two por- tions appears to prevail uniformly throughout the animal series. According to M. Serres, it is to be observed in all the classes of the ver- tebrate animals except the Reptiles ; but in them, according to him, the lateral fasciculi * are wanting. The latter assertion, however, is incorrect, the distinction being to be observed as satisfactorily in that class as in any other.f Again, the distinction is not equally remarkable in all ; in some it is still more so than in man ; in others it is less; and according to the same authority, it is to be observed among Mam- malia the more easily as we pass from Man to the Rodentia. Among the Cetacea it is divi- ded throughout into two separate fasciculi.}; Each of the two portions of which the nerve consists is a packet containing numerous fas- ciculi, which are again divisible into filaments. The fasciculi, of which the packets are com- posed, are differently circumstanced in different stages of the course of the nerve ; in one part they are bound up so closely together that they cannot without difficulty be separated from each other and disentangled, while in another they are but loosely connected and are easily sepa- rated. The two packets are associated together more or less intimately throughout their course ; but inasmuch as they present remarkable varieties in their disposition and mutual relations at dif- ferent parts, it may be advantageous to divide the nerve, through its course, into three por- tions or stages; one from the ganglion to the connexion of the nerve with the brain, which * The name by which he designates the lesser portion of the nerve, t See sketch of fifth nerve in the Turtle,/,?. 143. t Op. cit. may be denominated its internal or encephalic portion; a second from the ganglion to its ulti- mate distribution, its external or peripheric portion ; and, thirdly, its ganglion. Such a distinction may not be free from objection, but being adopted for the convenience of descrip- tion, it possesses at least the recommendation that there exist well-defined points of demar- cation, whether there exist or not any difference in the properties of those several portions. The nerve, in its encephalic portion, is partly within and partly superficial to the substance of the brain. The superficial part is from one-half to three-fourths of an inch in length, of a flattened form, and of very considerable size. It presents a loose fascicular texture, and is enclosed within a prolongation of the arachnoid membrane sent off upon it from the surface of the brain ; this prolongation is, as in the case of all those sent upon the vessels or nerves, in their passage from that organ to the parietes of the cranium, a cylindrical sheath, within which the nerve is enclosed ; it is at first remarkably loose, but as the nerve recedes from the brain, the membrane invests it more closely, and is continued upon it as far as the ganglion, from which it is reflected to the surface of the canal in which the nerve is contained. In the last particular the disposition of the membrane is subject to variety, for it is at times continued beneath the ganglion, and partially invests the trunks proceeding from this body before it is reflected to line the canal. Throughout this part of the nerve the two packets composing it are connected by cellular structure and vessels, and are enclosed within the prolongation of arachnoid membrane just described ; but there does not appear to be any interchange of nervous filaments between them, and they are connected so loosely that they can be separated from each other with great facility. They consist each of numerous fasciculi held together, like the packets themselves, so loosely that the latter can be easily opened out and decomposed. The fasciculi of both packets are irregular in size, some large, others small ; those of the larger are for the most part some- what smaller than those of the lesser, but they are much more numerous, amounting, accord- ing to J. F. Meckel,* to thirty or forty; while those of the lesser amount, according to the same authority, only to from nine to fourteen. The fasciculi again are composed of numerous and delicate filaments. The number of the fila- ments is very great, but differently estimated by different authorities; according to Meckel those of the greater packet amount to about one hundred, collected into thirty or forty fasciculi ; while, according to Cloquet,f the total number of filaments contained by both packets varies from seventy to one hundred, of which he allots five or six to the smaller, and the remainder to the larger packet. This difference of opinion Meckel explains by sup- posing that fasciculi have been taken for fila- ments and not decomposed, and this appears * Manuel d'Anatomic. t Anatomic Descriptive. 270 FIFTH PAIR very probable, inasmuch as Cloquet takes no account of fasciculi, and in his description of the smaller packet it is manifest that he has assumed the fasciculi, of which it is composed, to be filaments, for he does not attribute to it a greater number of filaments than it contains of fasciculi. But if Cloquet have underrated the filaments of the larger packet, Meckel junior has certainly overrated the fasciculi of the smaller one. From his account of the latter, it is to be concluded that it contains from three to fourteen fasciculi, but either of those numbers is too great, as will be seen from an examination of the subject, from which it will appear that they do not exceed the number attributed to them by Cloquet. The ultimate number of filaments, however, would seem to be somewhat uncertain, for it appears to depend very much upon the delicacy with which the separation of them may be effected ; and after all it is not a matter of any great importance. According to Wrisberg* and Scemmerringl the number of fibres contained in the greater packet is always less in the foetus than in the adult. The filaments of the smaller are stated by Cloquet to be larger, softer, and whiter than those of the other; but with regard to the difference of size it is probable that this opinion has arisen also from his having assumed the fasciculi to be filaments, inas- much as, when the fasciculi have been decom- posed, the filaments seem to be equally fine in both packets ; and for the other points of sup- posed difference the author has not been able satisfactorily to observe any in man. In other animals, however, — in some fish at least — a remarkable difference may be observed between the characters of the ganglionic and non-gan- glionic portions, the latter of which, in the Cod, is much softer, and of a darker, not whiter, colour than the other. The fascicular and filamentous disposition which has been described, is not, however, presented by the encephalic portion of the nerve through its entire extent, but only in that part of it which is superficial to the brain ; nor is it acquired by it until after it has emerged one or two lines from the substance of the organ, and then it does not assume it through- out at once, but at first superficially and later internally. The appearance of distinct fila- ments and fasciculi in one part and their ab- sence in the other appears owing to the exist- ence of neurilema in the former, for in one as in the other the nervous matter appears to be arranged in longitudinal tracts, which pre- sent in one case the form of expansions, and in the other are divided by the neurilema into separate cords ; and again the occurrence of the filamentous disposition earlier upon the surface than internally, is attributed to the superficial substance of the nerve being pro- vided with neurilema sooner than the inter- nal ; hence the length of the substance of the nerve without neurilema is greater internally * Observations Anatomicre de quinto pari ner- vorum, &c. t In Imdwig, Script. Neurol. Min. Ueber das Organ der Seele. OF NERVES. than externally, and when the nerve has been pulled away from its attachment to the brain, the rupture occurring at the point at which the neurilema commences, the part which is left projects in the middle, and presents a conical eminence of white matter: this, as Cloquet justly remarks, is but an incidental appearance, and not entitled to be considered, as it was by Bichat,* a real tubercle, from which the nerve arose. In neither packet are the fasciculi laid simply in apposition ; in both, but more remarkably in the larger, they are connected by frequent interchanges of filaments, and that to such a degree that the nerve when opened out appears to form an inextricable plexus, in which it is not improbable that every filament of it is connected directly or indirectly with all the others; this plexiform arrangement diminishes as the nerve approaches the gan- glion, before reaching which the fasciculi be- come more distinct. The fifth nerve is attached to the surface of the brain on either side of the pons Varolii, at a distance of three-fourths of an inch from its middle line. It is attached to the middle crus of the cerebellum, on its anterior inferior surface, about one-fourth of an inch from its superior, and half an inch from its inferior margin. The place of the attachment of the nerve to the exterior of the brain varies greatly in dif- ferent classes of animals ; in man, it is, as has been mentioned, the crus cerebelli on either side of the pons; in the other orders of the Mammalia it is either, as in the human sub- ject, the crus cerebelli, or, when the pons is less developed than in man, the nerve is at- tached behind that part between it and the trapezium of the medulla oblongata; in the other three classes of vertebrate animals, in which the pons and trapezium are both want- ing, the nerve is uniformly attached to the la- teral parts of the spina! bulb. This contrast is equally curious and important; it affords us a natural analysis, which will throw much light on the next step in our inquiry, viz. the origin of the nerve, or its ultimate connexion with the brain. It furnishes also, as has been sug- gested by Gall and Spurzheim,f an explana- tion of the complication which exists in the human being, in whom the great developement and the situation of the pons render it neces- sary that the nerve should traverse it, in order to reach the surface of the brain. At the attachment of the nerve to the crus cerebelli in the human subject, the non-gan- glionic portion or lesser packet is situate above and to the inner side of the greater. At that place it is separated or separable into two parts, while the greater continues undivided, and hence the nerve is described as having three roots, one for the greater and two for the lesser packet. The existence of two roots for the lesser packet had been announced by Santorini,! but they have been more parti- * Anatomie Descriptive. t Anatomie et Physiologie du Systeme Nerveux. X Observations Anatomical. FIFTH PAIR OF NERVES. 271 cularly and accurately described by Palletta.* They are distinguished by the latter into supe- rior and inferior, being attached to the eras cerebelli, one above and behind the other, and they are frequently separated from each other at their attachment by an interval of one or two lines or more. In such case the superior root is superior and parallel to the inner side of the greater packet, while the inferior is in- ternal to it, and, it may be, on a level with its inferior surface; hence, in such instances, the greater packet corresponds to the interval be- tween the roots of the lesser, and the inferior root of the lesser, in its course from the brain, is placed at first along the inner side of the greater packet, while the superior descends internal to the greater packet, and joins the inferior beneath it to constitute the lesser packet. This is not, however, uniformly the relation of the roots of the nerve at their at- tachment to the crus, for the distance at which they are placed from each other varies very much; in some instances the roots of the lesser packet are perfectly distinct and separated by the interval mentioned, the inferior being either in immediate contact with the greater packet, and even entering the crus through the same aperture, or being separated from it by an interval varying, according to J. F. Meckel, from a quarter of a line to a line; while in others the roots of the lesser packet are not manifestly distinct, but the fasciculi of which they consist are attached to the crus in an un- interrupted series reaching, from the attachment of the greater packet, to within a line or less of the posterior face of the crus, and separated the one from the other by trifling intervals; in the latter case the lesser packet is, for the most part, altogether superior to the greater at their attachment. But even in this the lesser is still distinguishable into two sets of fasciculi, which take different routes through the substance of the crus, one traversing it nearer to its ante- rior, the other to its posterior surface. It has been already stated that the lesser packet of the nerve is characterized by the absence of a ganglion; it also has no connexion with the ganglion of the larger packet, but passes it without entering into it, and then becomes attached to one of the trunks proceeding from it; it is further maintained to be distributed ultimately into those branches which are given by the third division of the fifth to the muscles of mastication. Palletta-I concluded from these circumstances that it was a nerve distinct from the remainder of the fifth ; and observing that the superior root was principally consumed in the temporal muscle, and the inferior in the buccinator, forming the long buccal nerve, he called the former the " crotaphitic," and the latter the " buccinator" nerves. The distri- bution of the leaser packet to the muscles of mastication has been confirmed by Mayo ]; from * Pallet'.a, De Nervis crotaphitico et buccina- torio, an. 1784. Script. Neurol. Min. Select. Lud- wig. t Op. cit. t Commentaries, and Physiology. the dissection of the nerve in the ass. He differs, however, from Palletta with regard to its distribution to the buccinator, which he denies : this point will come under considera- tion again. It has been proposed by Eschncht* to denominate it the masticatory nerve. The place at which the nerve is attached to the surface of the brain in the human subject is to be regarded only as the point at which it enters or emerges from the substance of the organ, inasmuch as it can be, without difficulty, followed to a much deeper part, and the fibres of the crus, which are transverse to those of the nerve, manifestly separate from each other, at the entrance of the nerve, to allow it a passage. The larger packet of the nerve is that whose course into the brain can be most easily traced; this circumstance depends partly upon the greater size of the packet, and partly upon the fact that, for the most part, its tracts are not separated from each other by those of the crus, but traverse that part in a body, the fibres of the crus seeming to be simply laid in apposi- tion with it, and connected to it by some deli-, cate medium ; while those of the lesser are, in the greater number of instances, separated from each other, or even interlaced with those of the crus ; hence the fibres of the crus may be easily raised, without injury to the nerve, from the larger packet, and its course be displayed, while the lesser cannot be followed but with difficulty. The larger is, however, subject to variety in the latter respect ; in many instances the fasciculi of the crus do traverse and divide it, and very frequently near its ultimate attach- ment, and this circumstance, when it occurs, renders the pursuit of its course more difficult ; but even here the fasciculus merely traverses it, and its tracts are not permanently separated, but reunite after the fasciculus has passed. The course of the packet may be exposed to a considerable extent even in the recent brain ; but for the satisfactory determination of the point, it is necessary that the brain be prepared by some of the methods recommended for that purpose, of which immersion in strong spirit is by far the best, nor does it require much time, for the substance will be found to separate more easily when it has acquired only a certain degree of firmness, than when hardened to the degree which long immersion produces; the plan which the author has found most success- ful has been to commence the dissection early, to return to it frequently, and at each time to pursue it so far and so far only as it was satis- factory. The course of the larger packet is also beneath and before that of the lesser, and hence, in the usual mode of dissection, in which the brain is reversed, it presents itself first. Its direction is backward, downward, and in- ward, toward the upper extremity of the spinal bulb ; in its course the packet first traverses the middle crus of the cerebellum from its an- terior toward its posterior surface, and from its superior toward its inferior margin ; it pursues this course until it has reached the back of the crus, and descended so low as its inferior mar- * Journal de Physiologie, t. vi. 272 FIFTH PAIR OF NERVES. gin ; it is then situate in the angle formed by the three peduncles of the cerebellum at their junction with the hemisphere; behind the middle, beneath the superior and above the in- ferior, and before, or in common language, be- neath the floor of the fourth ventricle. Thus far the course of the nerve may be ascertained without much difficulty; it is probably the same point to which Santorini had traced it, as described in his ' Observations Anatomicae,' in 1724, and from which Scemmerring has more expressly stated it to be derived, in his work ' De corporis humani fabrica,' pub- lished 1798, in which he states "that it ap- pears to arise almost from the very floor of the fourth ventricle." * At the point last described Fig. 140. Lateral view of the pons, spinal bulb, and course of the Fifth Nerve in man. 1 Pons Varolii. 2 Spinal bulb. 3 Olivary body. 4 Spinal cord. 5 Superior peduncle of cerebellum. 6 Cut surfaces of middle ditto. 7 Inferior peduncle of cerebellum. 8 Cut surface of crus cerebri. 9 Ganglion of Fifth Nerve reversed. 10 Ganglionic portion of the nerve. 11 Non-ganglionic portion of Fifth Nerve. 11 Roots of non-ganglionic portion. 12 Eminence at the insertion of both portions of the Fifth Nerve. 13 Fasciculus to anterior column of spinal cord- 14 Fasciculus to posterior column. 15 Auditory nerve. 16 Portio dura. 17 Posterior roots of superior cervical nerves. * Santorini, however, appears to have followed the nerve out into the spinal bulb, though, as will be seen, he did not succeed in determining its real and ultimate connection. the greater packet is attached to the side of the medulla oblongata. The point of attachment is very close to the interior of the fourth ven- tricle, being separated from it only by a thin lamina, which is little, if any thing, more than the " epithelium" of Reil : it is situate in the angle formed by the peduncles of the cerebel- lum, behind the middle one, by the outer margin of the pons, and posterior to it, and above its lower one : it is also superior to the attachment of the auditory nerve, separated from it by an interval of some lines. We shall, in the next place, direct attention to the course and connection of the lesser packet of the nerve. In none of the authorities which the author has had an opportunity of consulting, has he found a particular origin assigned to the lesser packet. By most anatomical writers it is over- looked ; J. F. Meckel states that it can be traced a certain way into the crus, but he goes no further; Mayo asserts that the lesser portion arises close upon the greater, and, in a sketch of the origins of the nerves given by him in his Physiology, it is represented traversing the crus cerebelli, as a single fasciculus, above and behind the greater, and attached to some part above that from which the greater is re- presented to arise : but still the origin is not defined, and it is manifestly intended to be distinct from that of the greater packet. The author has succeeded, as it appears to him, satisfactorily in tracing both the roots of the lesser packet to a destination for which he was not prepared ; at setting out he expected to have found the origin of the lesser different from that of the greater packet, and to have followed it to a prolongation of the anterior columns of the spinal cord, as has been stated by Harrison ;* it was therefore with surprise that, after a patient dissection, he succeeded in tracing both its roots to the same point, to which the greater packet is attached, behind the middle crus of the cerebellum (see Jig. 140, 12); both the roots traverse the crus, as the greater does, the inferior very frequently in company with and internal to the greater packet, or separated from it by a very thin stratum of the substance of the crus, the superior near to the superior surface of that part, and separated from the greater packet by an interposed stratum of two or more lines; the course of the latter is so near to the surface of the crus, that it can frequently be traced for a considerable way by the eye without dissec- tion : they present, in their mode of traversing the crus, two remarkable varieties ; in some in- stances the fasciculi, of which they are com- posed, are separated from each other and even interlaced with those of the crus, and in such the pursuit of them is intricate and difficult ; in others they pass in two distinct packets, and in these they are more easily followed. As they proceed they approach the greater packet, so that the interval between them and it gradu- ally diminishes, and having traversed the crus, they are both attached below and behind it to * Dublin Dissector. FIFTH PAIR OF NERVES. 273 the same part as the greater packet, and poste- rior to it. (See fig. 1 40). This view of the con- nection of the lesser packet, if confirmed, must lead to interesting results with regard to the rela- tions of the two portions of the fifth nerve at least ; it will at all events decide the question as yet in dispute, whether they are to be regarded as distinct nerves, or parts of the same ; upon this point further light will be thrown by the disposition of the same part in fish, in which the source of the uncertainty prevailing with regard to the nerve in the higher classes does not exist to the same amount ; inasmuch as the ganglionic and non-gangl ionic divisions of the nerve seem for the greater part associated in their distribution. Fig. 141. Back view of pons, bulb, and course of the Fifth Nerve in man, 18 Tubercula quadrigemina. 19 Continuation upward of the tract from which the Fifth Nerve arises. The other referenoes indicate the same parts as in the preceding figure. When the adjoining matter has been care- fully cleared away from the part to which the packets of the nerve are attached, that part ap- pears to be a longitudinal tract of a yellowish- white colour, composed of fibres running in the same direction, and capable of being followed both upward and downward : upward this tract seems continued beneath the superior peduncle of the cerebellum;* downward it descends from * Of the nature of the structure continued up- ward from the attachment of the nerve the author is not satisfied : it presents, when cleared, the ap- pearance given to it in fig. 141 , 19, but it is very cine- ritious in character, and he is not prepared to say whether it be a continuation of the tract from which the nerve appears to arise, or a part of the floor of the fourth ventricle at its upper extremity, con- nected to the attachment of the nerve : the mode in which the nerve arises in the bird and the turtle appears to the author opposed to the opinion that the tract to which the nerve is attached is, in them at least, any thing more than a continuation or VOL. II. behind the pons into the spinal bulb, and after a short course divides into two cords, one for each column of the spinal marrow (see Jigs. 140, 141). At the entrance of the tract into the bulb it is situate deep, before the floor of the fourth ventricle and behind the superficial attachment of the two portions of the seventh pair, which must be separated from each other and displaced in order that it may be ex- posed : externally the tract corresponds to the peduncles of the cerebellum, and is united in- ternally to the cineritious matter of the floor of the ventricle. At the point of attachment the tract presents a somewhat prominent en- largement, (Jigs. 140, 141, 12,) which the au- thor will venture to call an eminence, though with hesitation, lest it be considered an ex- aggeration, from which the nerve may be held to arise. It is said that the nerve may be held to arise from this tract, because, though it be certainly not its ultimate connection with the brain, and though cords can be traced from it to more remote parts, yet the union of the cords at the point, and the attachment of both portions of the nerve to it, seem to mark it as the origin of the nerve ; the change of character too which will be described as occurring at the attach- ment of the nerve, countenances the opinion that the tract is not simply a continuation of the nerve. It may be doubted whether the eminence really exist, or whether it be not merely the result of dissection : the author will not insist upon it, but several considerations induce him to consider it real : in the first place, he almost uniformly finds it,* and secondly, it seems to be a common point to the two portions of the nerve and to the other cords, which form part of its encephalic connections ; and lastly, this view is corroborated by the disposition of the same part in other animals ; for a similar ap- pearance will be found, at the attachment of the nerve behind the pons, in other mammalia as well as in man after the separation of the adjoining matter, e. g. in the horse ; and it is even asserted by Desmoulins that an eminence may be observed naturally upon the floor of the fourth ventricle, in some animals, at the attachment of the nerve. His statement is : " on observe meme dans les rongeurs, les taupes, et les herissons, un petit mamelon ou tubercle sur l'extremite ant6rieure du bord du ventricule ; mamelon, clans tequel se conlinuent les fibres posterieures de la cinquieme paire, et de l'acouslique." When the tract has reached the point at which the inferior peduncle of the cerebellum first inclines outward toward the hemisphere, it separates, as has been stated, into two parts or cords, (see Jigs. 140, 141,) destined, one, as is already known, to the posterior, the other, according to the author's belief, to the an- terior column of the spinal cord. The course and disposition of these cords are remarkable and root of the nerve, but admitting this, he cannot satisfy himself that it is to be regarded in the same light in the Mammalia. * The attachment of both the packets must be made out, else the enlargement will not appear. T 274 FIFTH PAIR OF NERVES. apparently contrary to analogy ; they are dis- tinguishable into anterior and posterior, but they descend, the anterior to the posterior, and the posterior to the anterior columns. The an- terior cord is by much the larger, and is pro- longed through the inferior peduncle of the cerebellum, until at the inferior extremity of the bulb it is continued into the longitudinal fasciculi of the corresponding posterior column of the spinal marrow ; it is situate along the outer side of the olivary body, but separated from it by a slight interval, nor does it seem to have any connection with that body : it is imbedded in the substance of the superior part of the peduncle, situate, however, nearer to its anterior than its posterior surface, and laid obliquely across its fibres as they pass outward toward the hemisphere of the cerebellum ; but as it proceeds it becomes gradually more super- ficial, gains the outer side of the peduncle, and at the lower extremity of the bulb is actually at its surface almost immediately behind the lateral fissure of the cord and the posterior roots of the superior cervical nerves. The existence and course of this cord have been first established and described by Rolando in his " Saggio sopra la vera Struttura del Cervello," and also in a memoir upon the Anatomy of the Medulla oblongata, published in the fourth volume of the Journal of Physiology. The posterior cord is much smaller than the former ; it descends behind the inferior pedun- cle of the cerebellum, as it passes outward into the hemisphere, and upon the posterior aspect of the spinal bulb ; enters the posterior fissure of the bulb, between the posterior py- ramids, and can be traced some way down- ward, in the bottom of the fissure, along the back of the anterior column of the same side, into which it appears to be ultimately con- tinued. (Figs. 140, 141, 13.) The preceding account of the encephalic connections of the fifth nerve differs very much from that adopted by some of the highest modern authorities. It is not necessary to allude to the opinions entertained upon the point, before the course of the nerve had ieen particularly inquired into; but, accord- ing to some of the most recent, the nerve arises from the groove between the restiform and olivary bodies, and from the olivary bodies themselves. Such is the view given of the origin of .the nerve by Gall and Spurzheim in their fifth plate of the brain, in which the nerve is represented breaking up, on the out- side of the olivary body, into several fasciculi, which plunge obliquely into it. In their account* of the course of the nerve into the brain they state, " on peut aisement suivre son cours entier jusq'au dessous du cote exterieur des corps olivaires ;" this might be, perhaps, interpreted to mean beyond the ulivuries, reference being had to the relations of those bodies in the erect posture ; but from the representation given it is obvious that the in- tended meaning is, that the nerve can be fol- 1 Anatomie et Physiologie du Systerae Ner- vciix, loin. i. p. 107. lowed to beneath, i. e. underneath, their outer side, the brain being placed in the manner ordinarily adopted for dissection, in which the anterior aspect of the olivaries is rendered superior; indeed their representation is alto- gether incompatible with the opinion that they had traced the nerve beyond the bodies. Such al so is the opinion of J. F. Meckel,* according to whom the nerve " passes under the posterior peduncle of the cerebellum, along the outer side of the pons, toward the groove between the olivary and restiform bo- dies, where it arises in part from the groove and in part from the olivary eminences." Cloquetf likewise states the nerve to arise between the olivary and restiform bodies, and has adopted and copied, in his late work,} the view given of its origin by Call and Spurz- heim. Further, the discovery of this origin of the nerve has been attributed by Meckel§ and others to Santorini. It is a hardy thing to contradict such au- thorities as have been quoted, and the influence which they justly carry with them has made the author hesitate before adopting a contrary opinion ; but if reference be made to the work|j of Santorini on the point, it will be found that he nowhere, in his account of the origin of the nerve, assigns the groove between the restiform and olivary bodies as its situation in the spinal bulb, as will appear from the following extract, the only paragraph of his account in which he particularizes it, and in which he supposes it to be situate between the olivary and pyramidal bodies : " Unde in interiorem medullas, ob- longata? caudicem conjectus, fere inter olivaria et pyramidalia corpora locatus, quo demum pergat, cum tenuium fibrarum implexus, turn earumdem mollitudo, ne consequerer, omnino prohibuere ;" from which it is plain, as has been stated, that he supposed the nerve to be between the two latter bodies ; and also that he had not been able to trace it to any particular destination, although, in a succeeding para- graph, he conjectures the olivary body to be its source : hence there is reason to conclude that succeeding anatomists have assumed his conjecture to be an established fact, and have modelled their accounts and representations accordingly. Moreover, since the olivary bodies .do not exist in the lower classes of animals, it is not likely that they should be points of origin or attachment for nerves ; in fine, the author has so uniformly succeeded in tracing the nerve to the destination which has been described, that he is satisfied of the accuracy of it, in which he is confirmed by the fact that the account here given accords with the opinions of Santorini, Scemmerring, and Rolando, so far as that of the first has been determined to be accurate, or as those of the others extend : the particulars in which it differs from, or rather in which it goes beyond these, rest upon the author's authority and remain to be confirmed, * Manuel d'Anatoinie, French edit, f Traite d' Anatomie descriptive. X Anatomie de l'Homme. S,Seenote5, p. 82, op. cit. vol. ii. | Observatioiies Anatomies. FIFTH PAIR OF NERVES. 275 viz . the attachment of the two packets to the same point, the existence of the eminence at the inser- tion, and that of a cord of communication with the anterior column of the spinal marrow. The encephalic connections of the nerve, as detailed, are corroborated by those to be observed in inferior animals. In those Mam- malia in which the pons is but little deve- loped, the nerve is attached between that part and the trapezium ; in those instances in which the pons is more so, the nerve is attached, superficially, not actually behind that part, but near to its posterior margin; with little trouble it can be followed to the back of the pons, where it is attached, as in Man, to the medulla oblongata, the point of attachment presenting here also, after the separation of the adjoining matter, the appearance of an emi- nence or tubercle, from whence a cord de- scends beneath the trapezium into the lateral column of the spinal bulb. This cord is of great size in many animals ; and in some can be seen distinctly, without dissection, upon the surface of the spinal bulb, in consequence of the degree to which it projects : it is well expressed in the delineation of the brain of the calf in the third plate of Gall and Spurzheim, and in that of the brain of the horse in fig. 275 of M. Serres' Illustrations of the Comparative Anatomy of the Brain. In Birds, Reptiles, and Fish, neither pons, trapezium, nor olivary bodies exist, and the nerve is attached to the lateral part of the spinal bulb at its superior or anterior extremity, and to its lateral column — the prolongation of the superior column of the spinal cord. In all three the point of attachment is situate a little way from the back of the bulb and be- neath the floor of the ventricle, the cineritioua stratum, of which the latter consists, being directly connected to the back of the nerve. In Birds (fig. 142) the continuation of the nerve Fig. 142. Brain and Fifth Nerves of the Goose. 1 Inferior surface of cerebrum. 2 Spinal bulb. 3 Ganglia of fifth nerves. 4 Root of nerve from lateral column of the bulb exposed by turning aside the superficial stratum of that part. 5 First division of the fifth. 6 Second do. 7 Third do. 8 Auditory nerve. On one side (the reader's right) the non-gan- glionic fasciculus has been traced beneath the gan- glion into the third division of the nerve. can be traced downward along the side of the bulb toward the spinal cord, and without diffi- culty, inasmuch as it is superficial and is not crossed by a trapezium, as in the Mammalia. In the Turtle the nerve can be traced in like manner from the point of attachment down- ward into the lateral column ; and in Fish the Fig. 143. Origin of nerve in Turtle. 1 Spinal bulb. 2 Fifth nerves. The pin is passed between the ganglionic and non-ganglionic fasciculi, the latter being continued into the third division. 3 Ganglion. 4 First division of the nerve. 5 Second do. 6 Third do. attachment is in all essentials similar : the com- parative small ness of the bulb and the direc- tion which the nerve takes in its course out- ward, make it resemble the spinal nerves more than in the other classes; but its encephalic connection is strictly the same, namely, to the lateral column of the bulb beneath the floor of the ventricle. In the Cod, after the removal of the floor of the ventricle from the back of the nerve, the latter may be followed for some way into the column, though neither to the same extent nor so satisfactorily as in the bird or the Turtle; and in the Ray, while the two inferior fasciculi of the nerve — for in this fish it consists originally of three — are connected in the usual mode to the lateral column, the superior is attached to a convolution formed by the floor, in consequence of a greater developement of its margin. In the Cod the convolution adverted to does not exist, but the floor of the ventricle cannot be raised from the nerve without destroy- ing a connection of some kind between them. In the latter fish the fifth nerve is attached before and rather superior to the auditory nerve, and the two nerves are quite distinct as far as the point of attachment, but there they are in t 2 ' Brain and Fifth Nerves of the Cod. 1 Non-ganglionic portions (on the reader's left c Third do side) separated from the ganglionic and thrown back. 2 Ganglionic portion. a First branches of both portions. b Second do. " d Fourth branch derived from both, e Fifth branch derived only from the ganglionic. The third division has been removed on the left side. immediate apposition and appear to have the same source. In the Ray it is different; in it (he auditory seems merely a branch of the fifth (Jig. 145, 7) given off from its posterior ganglionic fasciculus about three lines from its attachment to the spinal bulb, and before the formation of its ganglion. After the preceding details it must seem Fig. 14.5. Brain and Fifth Nerves of the Bay. a Anterior ganglionic portion of the fifth nerve. b Posterior do. c Non-ganglionic portion. On the reader's left it is laid back to display its connexion with the extraordinary if the nerve in the higher ani- mals differed, in its ultimate connection with posterior ganglionic ; on the right it is in situ. e First branches of the two portions. f Second do. 7 Auditory nerves. the brain, so very much from that in the in- ferior, as it is represented by some to 4o. FIFTH PAIR OF NERVES. Yet it is asserted by M. Serres,* who has founded his opinion upon the observations which he has made upon the successive de- velopement of the brain and nerves in the embryo of vertebrate animals, that in the Mammalia the nerve is implanted upon the trapezium. Such is the form of expression by which he intends, as the author understands, the ultimate connection of the nerve with the brain. Now, in the first place, we have al- ready seen where that connection is in those animals in which the trapezium does not exist, and it appears to the author reasonable to con- clude that similar nerves have similar or ana- logous attachments in the several classes of animals, however the parts with which they are connected may be complicated or ob- scured by superadded structures. In the second place the trapezium can be regarded only as a superadded structure, and is not among those parts from which nerves are likely to arise, being itself but a commissure: and, thirdly, the situation and connections of the part to which the nerve is attached, are altogether in- compatible with the opinion that it is the tra- pezium, inasmuch as the latter is situate be- fore the cords, which ascend from the anterior columns of the spinal cord to the crura cerebri, while the structure with which the nerve is connected is posterior to them. For these reasons the author concludes that M. Series has mistaken the place of the nerve's attach- ment in the Mammalia. In conclusion, the representation of the ori- gin of the nerve, which appears to the writer to be the most remote of all from the real one, is that given by Swan, in his plates of the nerves lately published, in which the fifth is re- flected into the auditory nerve : such a con- nection is merely artificial and does not really exist ; it can be produced only by stopping short in the pursuit of the fifth nerve, and mould- ing it into the anterior root of the auditory, which is in contact with it. This view of its encephalic attachment has probably originated in the intimate connection known to exist between the two nerves in in- ferior animals. The complication of the cere- bral connection of the nerve in the higher animals may be now better understood. In those, in which the pons and trapezium do not exist, the nerve emerges directly from the spinal bulb, in a manner similar to the ad- joining nerves ; but in those, in which the bodies alluded to are present, inasmuch as the attachment of the nerve is behind them, it can reach the surface only by either passing be- tween them, or traversing their substance. Hence, if the nerve simply traverse them, it ought not to receive any accession of fibres from them, and such, according to the writer's experience, is the case. As it emerges from the pons, the lesser packet receives an epithe- lium from its surface; but he has not been able to detect any fibres originating within the substance of that part. The structural arrangement, which the ence- * Op. cit. phalic portion of the nerve presents within the brain, is different from that, for which it is- remarkable, while superficial to it. Exter- nally it is, as has been stated, of a fascicular texture; but, within, that appearance is not to be observed : there the larger portion is a white, soft, homogeneous, flattened cord, the delicacy of which, in the natural state, forbids the separation of it into distinct parts ; but when sufficiently hardened, it may be divided into numerous thin strata, and these again into delicate fibrils. That such an arrangement is a natural, and not an artificial appearance, is manifest from the circumstance, that the sepa- ration into fibrils can be effected only in one direction, the length of the nerve, and that they break off when it is attempted in the other. The nerve retains those characters as far as its attachment behind the crus, but there they cease ; the pure white colour suddenly disappears ; the point of attachment and the cords descending from it present a cineritious tint ; and they are not absolutely distinct from the surrounding substance, as the nerve had previously been, but immersed in it ; they are, however, still manifestly composed of fila- ments, which may be rent either toward or from the point of attachment ; and after im- mersion in spirit they become nearly white. The course of the nerve, from its attachment to the surface of the brain, is forward and out- ward toward the internal anterior extremity of the petrous portion of the temporal bone ; it next passes over the superior margin of that portion, and descends upon its anterior surface into the middle fossa of the base of the cra- nium, where it reaches the Gasserian ganglion. During its short course, from its attachment to the brain, to the ganglion, it is at first contained within the proper cerebral cavity, by the side of the pons Varolii, and beneath the internal anterior angle of the tentorium cerebelli ; in the second place, in the middle fossa, it is not within the cerebral cavity of the cranium, but beneath it, separated fro n it by a lamina of dura mater; it is there contained in a canal or chamber, formed by a separation of the dura mater into two layers, between which the nerve and its ganglion are inclosed, one be- neath them attached to the bone, another above separating thein from the brain. This chamber is situate immediately external to, and lower than the cavernous sinus, but separated from it by the inferior lamina of the dura mater just described, which ascends from the bone to join the superior, and in so doing forms a septum between the two chambers ; it is about three-fourths of an inch long, reaching from the superior margin of the petrous bone to the anterior margin of the depression upon its anterior surface, in which the ganglion rests. In front this chamber is wide, containing at that part the ganglion, and sends fibrous offsets upon the nervous trunks proceeding from it; poste- riorly it is narrow, and presents an oval aperture, about one-third of an inch long, situate ex- ternal and inferior to the posterior clinoid pro- cess of the sphenoid bone beneath the attach- ment of the tentorium cerebelli to that process, 278 FIFTH PAIR OF NERVES. and also beneath the superior petrous sinus : by this aperture the chamber communicates with the cerebral cavity and the nerve enters. The chamber is lined by the arachnoid mem- brane, as far as the posterior margin of the gan- glion, but along this the membrane is reflected from the interior of the chamber to the nerve, and returns upon it into the cranium : hence the nerve is free within the chamber, while the dura mater is attached to the surfaces of tlie ganglion, and so closely that it requires care to separate it from them. The cham- ber presents a remarkable variety in its con- struction in some animals: in the horse, for instance, its parietes are not simply fibrous, as in man, but, frequently at least, in great part osseous, being at the same time lined by the membrane. The passage of the nerve over the margin of the petrous bone is marked by an inter- ruption in the sharp edge, which the bone presents external to that point, and its site upon its anterior surface, as also that of the ganglion by a corresponding shallow depres- sion. Throughout the course of this portion of the nerve, the relation of the two packets to each other varies ; at the attachment of the nerve to the crus cerebelli, the smaller packet, allowance being made for those vaiieties pre- sented by it in its mode of attachment, is superior and internal to the larger; in the in- terval between the crus and the margin of the petrous bone, the smaller packet gradually descends along the inner side of the larger, until it has reached the same level, so that the two packets are placed immediately side by side upon the margin of the bone, the lesser internal to the greater; but as the nerve pro- ceeds into the middle fossa, the smaller, at the same time, passes from within outward beneath the larger, and also beneath the gan- glion, toward its outer and posterior extremity; during this course it has no communication with the ganglion, but is quite distinct from it, though inclosed in common in the chamber formed by the dura mater, and connected with it by a dense cellular or fibrous structure; but having thus passed the ganglion, the lesser packet is united to the third trunk proceeding from that body, and with it constitutes the third division of the nerve. The larger packet, on the contrary, is at- tached to the ganglion. It has been before stated that the plexiform arrangement, which it presents, becomes less, as it approaches that body; its fasciculi become more distinct; they separate from each other, so that the width of the packet is greatly increased, and having rea hed the posterior margin of the ganglion they are received into the channel which it presents; in which they are ranged, in series, from one extremity of the body to the other, overlapped by its edges, and enter abruptly into the substance of the ganglion. External portion of the nerve. — The external orperipheric portion of the nerve consists of three large trunks or divisions, which are connected, on the one hand by their ramifications, with the organs to which the nerve is distributed, and on the other, with the ganglion and the brain. They are distributed, generally speaking, to three different regions of the head and face, one to the uppermost, another to the middle or superior maxillary, and the third to the lowest or inferior maxillary regions, and they are denominated, either numerically, first, second, and third, as by the first Meckel; or, according to the parts to which they are dis- tributed, the first the ophthalmic, by Willis; the second the superior maxillary, and the third the inferior maxillary, by Winslow. These methods of distinction have their several advantages. Could we select names which would give adequate ideas of the distribution of the trunks, the latter would certainly be preferable; but inasmuch as those which have been selected do not at all adequately express that distribution, and are attended, therefore, with the inconvenience of riot giving a suffi- ciently enlarged idea thereof, it would probably have been better, had the former been from the first adopted and adhered to, for such names could not create any incorrect impression with regard to the distribution of the several divisions of the nerve ; in fact, the epithets ophthalmic, superior, and inferior maxillaries ought to be altogether discarded, for, beside the objection to their use already stated, it will be found, upon reference to the anatomy of other animals, that they are by no means dis- tinctly appropriate, and that the circumstances upon which they are founded are purely inci- dental, associated with the peculiarities of the animal ; for the proof of which, see the com- parative disposition of the fifth nerve in the several classes. The three trunks differ from each other in size. The first, the ophthalmic, is the smallest; the second, the superior maxillary, is inter- mediate in size ; and the third, the inferior maxillary, is by much the largest. They are connected to the anterior convex margin of the ganglion, — the first to its superior internal extremity, the second to its middle, and the third to its inferior external extremity. At their attachment they are wide, flattened, and of a cineritious tint; but as they proceed they become contracted in width, cylindrical or oval in form, and of a white colour. Their texture is fascicular and compact, the fasciculi of which they are composed being bound up closely together, and they differ remarkably in com- position, the two first, the ophthalmic and superior maxillary, being derived altogether from the ganglion, and thus being, in anato- mical constitution, simple ; whereas the third is composed of two parts, one derived from the ganglion, and another formed by the lesser packet of the nerve, which does not join that body, and hence that division is compound. The trunks rest partly against the outer side of the cavernous sinus and in part upon the base of the cranium in its middle fossa, and they are enclosed in offsets from the fibrous chamber, in which the ganglion is contained. Their relative position corresponds to the posi- tion of the ganglion ; the first is superior and FIFTH PAIR OF NERVES. 279 internal to the other two, the second is inferior and external to the first, and the third is exter- nal, posterior, and inferior to both the others. They go off from the ganglion at different inclinations, the first forward and slightly upward, the second directly forward, and the third almost directly downward ; hence the first and second form a very acute angle with each other, while that between the second and third is much greater. First or ophthalmic division. — This division is distributed to the eye and its appendages, to the nostril, and to the forehead. It is the smallest of the three trunks proceeding from the ganglion, and is situate superior and inter- nal to the other two. It is about three-fourths of an inch long from the ganglion to its division into branches, and is contained thus far within the cranium. Its course is forward, upward, and slightly outward toward the upper part of the foramen lacerum of the orbit. It is laid against the outer side of the cavernous sinus, in company with the third and fourth nerves, and is contained in the external wall of the sinus, being separated from the interior of that chamber by a thin septum, which is a prolon- gation of the inferior internal wall of the canal in which the nerve and ganglion are contained. The septum is dense, but at the same time so thin and transparent that the nerve can be seen through it from the side of the sinus, while the lamina of the dura mater, by which it is sepa- rated from the interior of the cranium, is so thick and opaque, that the course of the nerve is a'together concealed from that side. At its outset the nerve is beneath, and external to the third and fourth nerves, and external and some- what superior to the sixth, which is within the sinus; but ascending as it proceeds, it gains, about the middle of the sinus, the same level with the third, placed still at its outer side, and inferior to the fourth, and then terminates by dividing into branches. Presently after its origin from the. ganglion the nerve is joined by one or more very fine filaments from the sympathetic : this is ex- pressly denied by the first Meckel, but he was certainly mistaken; they are very faithfully represented by Arnold. In order to display them the sixth nerve may be separated carefully from the carotid artery in the cavernous sinus, after which it will be found that branches of the sympathetic ascend upon the artery internal to that nerve, and distinct from those which are connected with it. Having surmounted it they branch off, some upon the artery as it passes to the brain, others to other destinations, and of the latter some incline outward above the sixth nerve and are connected to the first division of the fifth: they are short and very delicate. The first division of the fifth gives off no branch from its outset to its final division, except an extraordinary filament described by Arnold, and denominated by him the recurrent branch of the first division of the fifth. It arises from the upper side of the trunk immediately after it leaves the ganglion, runs backward above this body at a very acute angle, enters the struc- ture of the tentorium cerebelli, and divides be- tween its laminae into several very delicate fila- ments. The branches into which the first division of the fifth ultimately divides are either two orthree; according to the elder Meckel and the greater number of authorities they are three; according to others they are sometimes three, but are more frequently only two. The three branches are the frontal, the nasal, and the lachrymal. When the branches are but two, they are, according to J. F. Meckel, the nasal and the frontal, the latter in such case giving off that, which in the other mode of distribution is the third, the lachrymal. Theelder Meckel attributes the difference of opinion which prevails with re- gard to this point to the fact that the lachrymal nerve frequently has a second root derived from the frontal, which in such cases has been assumed to be the origin of the nerve. The names which have been applied to those branches have been taken either from their destination or from their relative course ; thus the frontal, so called from its distribution to the forehead, is also called the superior or middle branch; the nasal, so called because finally distributed to the nostril, the internal or inferior, and the lachrymal, which derives its name from the 'achrymal gland, the external. The three branches differ in size; the frontal is considerably larger than either of the others, the nasal is second, and the lachrymal is much the smallest. They all three traverse the orbit, but they pursue different routes, and have, at entering, very different relations. 1. The frontal tierve appears in the human subject, both from its size and itsdirection, to be the continuation of the original trunk. In other animals, however, it is otherwise: in them the predominance of the frontal nerve diminishes along with that of the superior region of the face, until in some it ceases to exist as a pri- mary branch of the first division of the fifth, and its place is supplied by a secondary branch of another, while the nasal branch increases in the same proportion, and seems ultimately to constitute itself the first division of the fifth.* The frontal nerve passes upward and forward toward the highest part of the forameii 1 ice rum of the orbit, and enters that region through it. It then continues its course through the orbit, to the superciliary foramen and escapes through it to the forehead. During this course it is. placed, before it has entered the orbit, at the outer side of the third nerve ; it then rises above the third and crosses over it to its inner side. In doing so it is accompanied by the fourth nerve, to which it is external and in- ferior; it enters the orbit in company with the fourth and nearly on the same level, but still external to and somewhat beneath it. In entering, it passes above the origin of the superior rectus muscle, and all the other pans transmitted through the foramen lacerum, with the exception of the fourth nerve. At the en-, trance of the frontal nerve into the orbit and during its course from its origin thereto it is * See comparative distribution of the fifth rieive, 280 FIFTH PAIR OF NERVES. closely attached to the fourth nerve, but pre- sently after separates from it, the fourth in- clining inward, is continued forward to the superciliary foramen, lying upon the superior surface of the superior rectus and levator palpe- bral muscles, being through its whole course within the orbit immediately beneath its roof. Having reached the foramen it passes through it, and changing its direction, ascends round the superciliary arch, upon the forehead, be- neath the orbicularis palpebrarum and frontalis muscles, and is thenceforth called by some the external frontal nerve in contradistinction to a branch from itself, the supra-trochlear,or internal frontal. In its mode of escape from the orbit the frontal nerve is subject to some variety, consequent in part upon the mode in which the superciliary foramen is formed, that being in some instances altogether osseous, in others osseous only at its superior part and completed by ligament below; in this case the nerve escapes through an osseous notch, and not a foramen. In other instances, again, when the nerve divides previous to its escape it is some- times transmitted through two apertures. The distribution of the frontal nerve, as well as that of most of the secondary branches, is subject to varieties, which the author has en- deavoured to embrace in the following account. In the first place the frontal, at its entrance into the orbit, anastomoses with the fourth nerve. Next it gives off, some time after its entrance and previous to its division, a long and slender branch, which runs forward and inward toward the trochlea of the superior oblique. Then it divides into two branches, a larger one, the continuation of the nerve, which escapes through the superciliary foramen, and a smaller, the supra-trochleur or internal frontal. The latter passes forward and at the same time inward toward the trochlea of the oblique muscle, escapes from the orbit internal to the continued trunk of the frontal nerve, and ascending upon the forehead beneath the coirugator supercilii, orbicularis, and frontalis musc'es, it has received the name of internal frontal, in contradistinction to the continued trunk, which is at the same time called external frontal. The point at which the frontal divides is variable; for the most part the division takes place about midway in the orbit. In some instances it occurs before the nerve has reached that point, and in others, again, not until it has approached nearer to the anterior margin of the orbit. The distance of the division from the margin of the orbit appears to modify the course of the internal branch : when it is far back, the nerve escapes from the orbit above the trochlea, and hence the name supra-tro- chlear, given to it by Meckel ; and when near the margin it escapes external to the trochlea, be- tween it and the superciliary foramen ; while in the latter case a branch of the nerve is transmitted above the trochlea, in the usual course of the nerve itself. Nor is the size of the two branches into which the frontal divides equal or uni- form ; for the most part the external branch is the larger, but in some instances the two are of equal size. In its course forward the supra- trochlear nerve gives off first, occasionally a delicate branch, which frequently arises from the frontal itself prior to its division, the course and destination of which have been already described. Next it gives off, in some instances before, in others not till after it has escaped from the orbit, a branch which passes inward toward the internal canthus, and, uniting with either the infra-trochlear itself or a branch of it, concurs in forming a small plexus, from which filaments are distributed to the structures of the upper eyelid, toward its internal part, and to the eyebrow. Having escaped from the orbit, the supra-trochlear nerve divides into two sets of branches, denominated palpebral and frontal ; the first descend into the superior eyelid, and are distributed to the structures of that part ; the filaments communicating exter- nally with those of the frontal, and internally with those of the infra-trochlear. The frontal branches ascend round the superciliary arch, beneath the orbicularis palpebrarum and the coirugator supercilii muscles, upon the fore- head, and these are disposed of in a manner similar to that in which the branches of the proper or external frontal are. Some are dis- tributed to the orbicularis, corrugator, and fron- talis muscles ; other, long branches, ascend beneath the frontalis, traverse it, and become subcutaneous, and are distributed to the inte- guments of the scalp upon the forehead. Of these the external unites with the internal branch of the external frontal, and forms with it a common branch, which has the same destination as the others. The external larger branch of the frontal, called, in contrast with the last, the external frontal nerve, also divides into two sets of branches, palpebral and frontal. The nerve in some instances emerges from the orbit a single trunk, in others it divides be- fore it escapes from that region, for the most part into two branches, which are transmitted sometimes through the same, at others through distinct apertures, and from which the several ramifications arise, they themselves becoming ultimately the long frontal branches. Immediately after their escape the frontal branches give off externally slender filaments, which run outward toward the external can- thus, one beneath the eyebrow, through the upper eyelid, and one or more through the brow itself; these ramify as they proceed, sup- ply the lid and brow at their outer part, and anastomose with filaments of the portio dura, and of the superficial temporal nerve. The frontal branches are arranged into super- ficial and deep ; those epithets have been diffe- rently applied by different writers ; thus those which the elder Meckel terms the superficial, Boyer and Cloquet denominate the deep branches ; nor is this to be wondered at, inas- much as both sets become ultimately superficial ; it were better, perhaps, to arrange them into short and long branches. The short branches are distributed to the orbicularis muscle, the corrugator, and the frontalis, and having sup- plied those muscles, they or others of them be- come subcutaneous, and terminate in the inte- FIFTH PAIR OF NERVES. 281 guments of the eyebrow and forehead : one of these branches, as described by Meckel, runs outward, through the orbicularis, toward the external canthus, and establishes anasto- moses with filaments of the facial portio dura nerve. The long branches are two, an external and an internal ; of those the external is, for the most part, the larger ; they ascend beneath the frontalis and the frontal aponeurosis, the former inclining outward, the latter inward, as they ascend ; they distribute in their course ramifications to the muscle, and to the deeper structures of the scalp, as well as some- times, according to Meckel, to the pericra- nium, and traversing the frontal aponeurosis, they become subcutaneous, and terminate in the structure and integument of the scalp. The external communicates with the superficial temporal nerves ; the internal with the internal frontal, the supra-trochlear. They are said both to anastomose with the branches of the sub- occipital nerve ; but Meckel states that he has pursued them until they have escaped his sight, and yet he could not discover any anastomoses between them and the branches of that nerve. 2. The nasal nerve is in size the second branch of the first division of the fifth, and arises always separately from the original trunk. Its course is inferior and internal to those of the other two, and hence the nerve is called by some the inferior, by others the internal branch. It is distributed partly to the eye and its appen- dages and partly to the nostril, and hence it is also called naso-ocular by Scemmerring. The direction of its course is forward and very much inward; it passes through the foramen lacerum into the orbit ; then traverses that re- gion from without inward toward its internal wall, and having reached it at the foramen or- bitarium internum anterius, it escapes from the orbit through that foramen, and passes into the cranium ; it emerges into the cranium from beneath the margin of the orbitar process of the frontal bone, and crosses the cribriform plate of the ethmoid obliquely forward and inward, contained in a channel in the bone, and in- vested by the dura mater, until it reaches the crista gal 1 i ; it then descends from the cranium into the nostril, through the cleft, which exists at either side of the crista galli at the anterior part of the cribriform plate, and having reached the roof of the nostril, it divides into its final branches.* The nasal branch is concealed at its origin by the frontal, which is situate external and superior to it. Before its entrance into the orbit it is placed by the outer side of and closely ap- plied to the third nerve. In entering the orbit * The nasal is usually described as terminating by dividing within the orbit into two branches, the ethmoidal or internal nasal, and the infra-trochlear or external nasal : the author has preferred considering the former as the continuation of the nerve, be- cause in inferior animals both the nasal is the prin- cipal portion of the first division of the fifth, or alone constitutes it', and it is manifestly prolonged, as such, into the nostril and the beak. See Com- parative Distribution, it passes between the two.posterior attachments of the external rectus muscle, in company with the third and sixth nerves, external to the former and between its two divisions, and internal and somewhat superior to the latter. In its course across the orbit the nasal nerve passes above the optic nerve, immersed in fat, and accompanied by the ophthalmic artery, being at the same time beneath the levator palpebral, ihe superior oblique, and superior rectus muscles, and in crossing the optic nerve, it is placed between it and the last mentioned muscle. Through the foramen or- bitarium the nerve is accompanied by the an- terior ethmoidal artery, and within the cra- nium is situate beneath but not in contact with the olfactory bulb, being separated from it by the dura mater. The course of the nerve from the orbit to the nostril is liable to be modified by the developement of the frontal sinuses ; when they are very large, and extend, as they not unfrequently do, into the orbitar processes of the frontal bone and the horizontal plate of the ethmoid, the nerve may cross to the side of the crista galli without entering the cranium, being contained in a lamella of the ethmoidal bone. The nasal branch, before entering the orbit, receives, according to Bock, J. F. Meckel, and Cloquet, a filament from the sympathetic. The branches which the nasal gives ofT, are the lenticular, the ciliary, the infra-trochlear, and the nasal. The lenticular branch is given off as the nasal enters the orbit, and on the outer side of the optic nerve; it is a delicate branch, about half an inch long; it first anastomoses with the supe- rior division of the third nerve ; then inns for- ward along the outer side of the optic nerve, and terminates by joining the superior and pos- terior part of the lenticular ganglion. Accord- ing to Bock and Meckel junior, it occasionally gives off a ciliary nerve, and according to Meckel senior it is, in rare instances, derived from the third nerve. To the latter statement, however, the author hesitates to assent : it ap- pears to him, that it should rather be said in such cases to be wanting. The ophthalmic, lenticular or ciliary ganglion, according to Cloquet, is of an oblong form — its greater length from behind forward ; it is one of the smallest ganglia of the body, being, however, variable in size ; its colour is reddish, at times white ; it exists constantly in the human subject : it is situate between the external rectus muscle and the optic nerve, laid against the outer side of the nerve, at a little distance from its entrance into the orbit ; its external surface convex, corresponding to the muscle ; its internal, concave, to the nerve ; to its superior posterior angle is attached the len- ticular twig of the nasal branch of the first division of the fifth ; this filament constituting its long root ; to its inferior posterior angle a filament from the inferior division of the third nerve is attached, constituting its short root. To the posterior part of the ganglion are also attached two filaments derived, one from the cavernous ganglion or the carotid plexus ; the other, the constant existence of which has not 282 FIFTH PAIR OF NERVES. been yet established, from the sphenopalatine ganglion. The ganglion gives off from its anterior ex- tremity a considerable number of very delicate filaments, denominated from their distribution ciliary : they amount to from twelve to sixteen ; are reddish and tortuous; and run forward along the optic nerve to the back of the eye, which they enter at a short distance from the nerve. They are distinguished into two fasci- culi, superior and inferior ; which are attached, one to the superior anterior, the other to the inferior anterior angles of the ganglion : the former is the smaller ; contains at first but three filaments, which, as they proceed, divide so as to produce six, and run parallel to each other above the optic nerve: the second fasciculus is situate on the outside of and beneath the optic nerve, and contains from six to ten filaments col- lected at their origin into six branches : they pass beneath the nerve and incline inward, so as to gain, some of them, its inner side : one of them runs outward and joins one of the ciliary branches of the nasal nerve. The ciliary nerves all penetrate the sclerotic coat of the eye sepa- rately and obliquely ; then run forward between the sclerotic and choroid coats, without giving filaments to either, lodged in channels upon the inner surface of the former:, as they ap- proach the ciliary circle they divide, each into two or three filaments, which enter the circle and are lost in it : some of them pierce the choroid at the anterior part of the eye, and go to the ciliary processes. The ciliary branches are two or three in number ; they are very delicate, and are given off, while the nasal is crossing the optic nerve ; they run forward along the optic, imbedded in fat, penetrate the sclerotic coat of the eye pos- teriorly, and then continue forward between the sclerotic and choroid coats, in like manner as the other ciliary nerves, to the ciliary circle. The infra-trochlear brunch, so called by the elder Meckel, because it escapes from the orbit beneath the trochlea of the oblique mus- cle, is also called external nasal. It is given off when the nasal has reached the inner wall of the orbit, and as it is about to enter the fora- men orbitarium ; it is a branch comparatively considerable, at times longer, at others smaller decidedly than the continuation of the nasal ; it runs directly forward along the inner wall, beneath the superior oblique muscle, toward its trochlea, and having reached that, escapes from the orbit beneath it. It then divides, in the internal canthus of the eye, into two branches, a superior and an inferior. The infra-trochlear, while within the orbit, gives off occasionally, soon after its origin, a small branch, which returns and joins the nasal before it enters the foramen orbitarium ;* also a delicate branch, which joins a corre- sponding branch given off either by the supra- trochlear or the frontal. The distribution of the nerve resulting from their junction has been already described under the frontal nerve. Of its ultimate branches, the superior joins and forms a plexus with a branch of the supra-tro- chlear nerve, already described, given off either immediately before or after that nerve has escaped from the orbit. From the junction of the two, numerous delicate ramifications are distributed to the upper eyelid and to the eye- brow. The inferiorgives off several ramifications, which are distributed to the origin of the cor- rugator, the orbicularis, and the pyramidalis nasi muscles ; to the conjunctiva, at the inter- nal canthus ; the carunculalachrymalis and the lachrymal sac. Of those ramifications, one de- scends before the tendon of the orbicularis, and communicates with a branch of the portio dura: another communicates with a branch of the infra-orbital; but the latter anastomosis is uncertain.* The nasal nerve having entered the nostril di- vides at the roof of the cavity into two branches, an external and an internal: of these the former descends behind the nasal process of the frontal and the corresponding nasal bones, contained in the groove or canal observable upon their posterior surface. It escapes from beneath them at their inferior margin, emerging between it and the lateral cartilage of the nose, and then descends along the corresponding ala, superfi- cial to the cartilage, and covered by the mus- cles of the ala, toward the tip : as it approaches the tip, it divides into two filaments, one of which is distributed to that part, and the other to the ala. During its descent along the side of the nose it also gives off some delicate fila- ments, and anastomoses with the ramifications of the nasal branches of the infra-orbital nerve and with the portio dura. It is called by Chaussier the naso-lobar : it is also generally known as the nerve of Cotunnius. The second branch, as it proceeds, divides presently into two, of which one attaches itself to the septum, and descends, between the pituitary membrane and the periosteum, parallel and near to its an- terior margin, as the 7iaso-palatine of Scarpa does to its posterior : as it proceeds, it furnishes ramifications to the membrane of the septum. The second attaches itself to the outer wall of the nostril, and descends, in like manner be- tween the mucous membrane and the perios- teum, along its anterior part, in front of the middle turbinate bone, until it reaches the an- terior extremity of the inferior one : it then breaks up into branches, of which some are distributed to the convex surface of the latter bone in front, and others beneath it to the an- terior part of the inferior meatus. The distri- bution of the branch is very happily represented in Arnold's Icones. The nasal nerve is described as giving also, in some instances, but not uniformly, a branch to the membrane of the superior turbinate bone, at the superior part of the nostril. 3. The third branch of the first division of the fifth is the lachrymal: it has been so called by Winslow from its distribution to the lachrymal gland : it is the smallest of the three branches : its course is external to that of the others, and hence it is also called the external branch. It » J. F. Meckel. * The elder Meckel. FIFTH PAIR OF NERVES. 283 arises, for the most part, from the ophthalmic at the same time with its other branches ; J. F-. Meckel asserts that it arises more fre- quently from a trunk common to it and the frontal ; but the contrary is maintained by the elder Meckel ; he, however, states that it arises frequently by two roots, one from the ophthalmic, and a second from the frontal, and once he has seen it derive a root from the tem- poro-malar branch of the superior maxillary nerve.* When it arises from the ophthalmic, it is at its origin, inferior to the frontal, and exter- nal to the nasal. Its course is forward and outward at a very acute angle with the frontal ; it enters the orbit through the foramen lacerum, and from its origin until its entrance it is con- tained in the dura mater lining the inner side of the middle fossa of the base of the cranium, beneath the lesser wing of the sphenoid bone : in entering it passes above the origins of the external rectus muscle, between it and the pe- riosteum, and pursues its course along the outer wall of the orbit, external to the superior rectus and superior to the external, until it reaches the lachrymal gland : it then passes between the gland and the eyeball, and then divides into branches. It is accompanied through its course by the lachrymal artery. The branches into which it divides are, for the most part, three ; they enter the gland on its ocular surface, traverse it and ae^un escape from it on its external aspect ; in their course through the gland they divide and commu- nicate with each other, and thus form within it a plexus, from which numerous ramifications are distributed to its substance. After having supplied the gland the branches of the lachry- mal emerge from it, and pursue two destina- tions : one of them, which is for the most part the first branch of the nerve, and is frequently given off before it has reached the gland, de- scends backward toward thespheno-maxillary cleft, and joins the temporal branch of the temporo-malar branch of the second division of the fifth. In its course this branch passes first between the external rectus muscle and the outer wall of the orbit, then becomes attached to the wall, and is either simply inclosed in the periosteum, or contained in a groove or canal in the orbitar process of the malar, or some- times of the sphenoid bone ; in this canal it meets the branch of the temporo-malar, and from the junction of the two results a filament, the des- tination of which will be described under that of the temporo-malar. This branch of the lachrymal nerve is called the posterior or sphe- nomaxillary : it might from its destination be appropriately termed temporal: it frequently gives off in its descent a filament, which passes forward, escapes from the orbit beneath the ex- ternal canthus, and is distributed as the other branches of the lachrymal are. The remaining branches of the lachrymal escape from the orbit into the upper eyelid, beneath the exter- * [According to Cruveilhier the lachrymal nerve very often arises by two filaments, one from the ophthalmic, the other from the fourth nerve, and Swan describes this as the normal condition. — Cruveilhier, Anat. Descr. t. iv. p. 911. — Ed.] nal part of the superciliary arch. They give off numerous filaments, which are distributed to the structures of the lid, the conjunctiva, the orbicular muscle, and the integument : the ex- ternal of them, which are the largest, not only supply branches to the upper, but descend be- hind the external commissure of the lids into the lower one, which they supply at its outer part; they are also distributed to the superfi- cial parts on the malar region. They anasto- mose with the frontal nerve, the superficial temporal, the facial, the temporo-malar, and the infra-orbital nerves. The second division of the fifth. — This has been called also by Winslow, in consequence of its distribution, the superior maxillary nerve. It is the second trunk connected with the Gasserian ganglion, and is intermediate to the others, both in size and situation ; larger than the first, and placed beneath and external to it; smaller than the third, and situate internal, superior and anterior to it ; it is attached to the middle of the anterior convex margin of the ganglion ; at first it is flattened, wide, and of a cineritious tint ; but, as it proceeds, it becomes contracted in width, of a cylindrical form, and presents a white colour. At leaving the gan- glion it is joined by a filament of the sympa- thetic. This has been seen by Munniks* and Laumonier,f and is stated by Meckel junior, on the authority of the latter. The communi- cation between the sympathetic and the second and third divisions is called in question by Arnold.} That with the third the author has not yet made out, but that with the second he has found satisfactorily established by a fila- ment from the branch of the sympathetic which joins the sixth nerve : this filament connects the sixth to the second division of the fifth, and is short, but grosser than those which join the first : in consequence of the irregularity which pre- vails in the arrangement of the sympathetic system, the description here given may not apply in other instances. The course of the second division of the fifth within the cranium is short ; it is directed for- ward, slightly outward and downward, toward the superior maxillary or the foramen rotundum of the sphenoid bone ; having reached that foramen it enters the canal, of which it is the aperture, and escapes through it from the cranium. While within the latter the nerve is contained in a sheath of dura mater, and rests in a shallow channel on the body of the sphenoid bone, at its junction with the great ala. From the cranium it enters the spheno-maxillary fossa, and crosses that fossa at its superior extremity, from behind forward, inclining still downward and outward, though but slightly ; its course across the fossa is also very short, extended between the root of the pterygoid process behind and the highest part of the posterior wall of the maxillary antrum before ; having traversed the superior part of the fossa it enters the infra-orbital canal, through * De Origine nervi intercostalis. t Roux, Journ. de Med. t. xciii. X Journ. Comp. t. xxiv. 284 FIFTH PAIR OF NERVES. which it is transmitted, in company with the in- fra-orbital artery, to the face. In the canal it is situate in the floor of the orbit or the roof of the antrum, separated from each cavity, more or less perfectly, by a thin lamina of bone ; its course within the canal is by much its longest stage ; as the nerve approaches the anterior extremity of the canal, it inclines inward, and thus its course is rendered a curve, convex outward. In this respect, however, it pre- sents varieties, dependant upon the transverse dimensions of the face, which being great, the course of the nerve is more curved and vice versa, it being sometimes nearly straight. From the time that the nerve enters the canal, it has been called infra-orbital ; but, inasmuch as that part of it is manifestly but the con- tinuation of the trunk, and names are already rather too numerous than otherwise, it would be better if that one were discarded. From the infra-orbital canal the nerve escapes through its anterior aperture into the face ; that aperture corresponds, for the most part, to the point of junction of the two external with the internal third of the inferior margin of the orbit, and is from a quarter to half an inch below it ; its situation, however, is not uniform ; in some skeletons it wdl be found to correspond nearly to the middle of the margin, and this circum- stance is worthy of attention, in consequence of its relation to the operation for the division of the nerve. At its escape from the canal the nerve is concealed by the lower margin of the orbicu- laris palpebrarum and by the levator labii supe- rioris muscle, beneath which it is placed, and it is above the upper extremity of the origin of the levator anguli oris : immediately after its escape it separates into a number of branches, which go off in different directions to their several destinations, but principally downward. The branches which the second division gives off are the temporo-malar, the spheno- palatine, the posterior superior dental, the an- terior superior dental, and the facial branches. While within the cranium the nerve gives off no branch. 1. The first branch given off by the second division, the temporo-malar, has been called cutaneous malar by the elder Meckel ; it has been also called orbitar, but without good reason ; the name temporo-malar fully expresses its distribution. This branch is given off by the nerve, either while yet within the canal, through which it escapes from the cranium, or after it has entered the spheno-maxillary fossa ; it is one of its smallest branches ; it passes for- ward through the fossa, toward the spheno- maxillary cleft, enters the orbit through the cleft, and then pursues its course forward and outward, along the floor of that region, beneath the inferior rectus muscle, and about the mid- dle of it divides into two branches ; an exter- nal, the temporal, and an anterior, the malar. Before entering the orbit it sometimes gives off a small branch, which enters that cavity through the periosteum of the posterior part of the orbitar process of the sphenoid bone, and joins the lachrymal branch of the first division, presenting one of the instances of a second root to that branch, as described by the elder Meckel. The external temporal branch passes toward the outer wall of the orbit, ascends between it and the external rectus muscle ; then becomes attached to the wall, and continues its course either through the periosteum, or in a groove, or at times through a canal in the orbitar pro- cess of the malar, or occasionally of the sphe- noid bone ; here it is joined by the posterior temporal branch of the lachrymal nerve, the third branch of the first division : the conjoined branch is then transmitted into the temporal fossa, through an aperture on the temporal sur- face of the orbitar process of the malar bone ; there it is joined by a small branch of the an- terior deep temporal branch of the inferior maxillary or third division of the fifth, and plunging among the fibres of the temporal muscle, it is distributed to them in common with the filaments of the deep temporal ; a filament or filaments of it gain the superficial surface of the muscle, perforate its aponeurosis, become subcutaneous, and are distributed su- perficially upon the temple, communicating with filaments of the portio dura, and of the superficial temporal branch of the third divi- sion. The temporal branch of the temporo- malar is sometimes double, or divides into two, one communicating with the branch of the lachrymal, the other transmitted to the temple. The malar branch pursues the course of the original nerve, until it has reached nearly to the anterior margin of the orbit, at its inferior external angle ; then it enters, either single or divided into two, the corresponding canal or canals, by which the malar bone is perforated, and through them is transmitted outward and forward to the malar region of the face. Its ramifications are distributed to the inferior ex- ternal part of the orbicularis palpebrarum, and to the integuments of the malar region ; they communicate with those of the portio dura, of the superficial temporal and lachrymal nerves, and of the palpebral branches of the second division. Before reaching the malar canals, the malar branch frequently gives off one or more filaments, which ascend to the lachrymal gland, unite with those of the lachrymal nerve, and follow a similar distribution. •2. The branches, which are given off next by the second division of the fifth, are those by which the nerve is connected to the spheno- palatine ganglion; they are hence denominated the spheno-palatine ; the ramifications derived from thein, or from the ganglion with which they are connected, are distributed to the nos- tril and the palate, and they may hence with more propriety be termed the naso-palatine, an appellation which is the more appropriate, since it is already applied to the corresponding branch of the second division of the fifth in other animals. It is at the same time to be borne in mind that a difficulty has been created in this matter by the application of the epithet in question to certain secondary branches, to be mentioned by and-by; but the latter use of the term ought to be discarded. They are irregular in number, there being sometimes but one, at FIFTH PAIR OF NERVES. 285 others two or three : they are short and of con- siderable size, and arise from the inferior side of the nerve, immediately after it has entered the spheno-maxillary fossa ; they descend from it, almost perpendicularly, into the fossa, pos- terior to the internal maxillary artery, and im- mersed in fat, and after a very short course they are connected to the ganglion, from which they may seem to ascend to the nerve. They are thus described by Cloquet, but this view is not sanctioned either by comparative anatomy, or by the result of experiments, both which prove that they are to be considered branches of the nerve, with which the ganglion is con- nected. The ganglion has been first described by the elder Meckel,* and hence has also received the title of Meckel's ganglion ; it is very small, of a grey colour, and firm consistence ; its shape is triangular or cordiform, one surface directed outward, the other inward ; it is situate immediately external to the spheno-palatine foramen, its internal surface, which is flat, cor- responding to the foramen, its external, which is convex, to the zygomatic fossa. It is subject to variety ; in some instances it is wanting, and then the spheno-palatine nerve gives off those branches which otherwise arise from the ganglion : in other rare cases, according to Meckel, the two principal branches, which arise from the ganglion when present, or from the spheno-palatine when single, viz. the Vidian and the palatine, proceed separately from the trunk of the second division of the fifth ; in others again the author has observed a cineri- tious soft enlargement upon the Vidian nerve at its junction with the spheno-palatine, but not involving that nerve or the branches pro- ceeding from it ; and this, it is worth remark- ing, is precisely the disposition of the ganglion in the dog and some other animals. Different views have been taken of the nature and rela- tions of this ganglion : the Meckels, by the elder of whom it was discovered, Bichat, Boyer, and others, have regarded it as belonging pro- perly to the fifth nerve, and formed by the branches which have been mentioned : Cloquet, on the other hand, considers and describes it as a part of the ganglionic or sympathetic system, and all the nerves connected with it, as well the original spheno-palatine branches as the others, to be branches from it : Cruveil- hier again, while he admits the existence of ganglionic structure, yet leaves it uncertain whether he regards it as a sympathetic or a cerebro-spinal ganglion, but he differs from Cloquet in maintaining that " the nerves," which seem to arise from it, " are not detached from the ganglion itself, and come directly from the superior maxillary." The opinions of Cloquet and Cruveilhier appear to the author to be both, to a certain degree, well-founded. The ganglion would seem not to be properly a part of the fifth nerve, because, 1 . it is not, as he believes, present in animals below the mam- malia ; 2. it is not always present even in them, and in neither case is the general distribution of the part of the fifth nerve, with which it is connected, influenced by its absence ; 3. it is manifestly different in its characters from the fifth nerve and from the branches of the nerve to which it is attached, nor does it resemble the cerebro-spinal ganglia, the peculiar appear- ance of these bodies, viz. white filaments enter- ing and emerging, their continuity being appa- rently interrupted by an interposed mass of cineritious matter, not being observable ; while, on the other hand, it resembles the ganglia of the sympathetic, and is actually connected with that nerve by a branch having precisely the same qualities with those which proceed from it, viz. by the inferior branch of the Vidian nerve : for those reasons the author would adopt the opinion of Cloquet, that the ganglion is properly a part of the ganglionic system, and that it is only accessory to the fifth nerve. On the other hand, it appears to him that Cloquet is mistaken in considering the ganglion as the source of all the nervous filaments connected with it, and more particularly of the spheno- palatine branches of the second division of the fifth, to which in man the ganglion is attached, for, as has been already stated, the general dis- tribution and existence of these branches are not at all influenced by the absence of the gan- glion, and when present it allows in general, as Cruveilhier has observed, the nerves to be fol- lowed up and down from the swelling, and lastly, any obscurity existing with regard to this point in the human subject will be at once removed by reference to the disposition of the ganglion in other animals, in none of which that the author has examined does it involve the nerve, but is merely connected to it either by filaments or by one extremity, the continuity of the nerve being altogether uninterrupted, and a marked contrast being to be observed between the characters of the two parts : thus in the dog, the ganglion is an oblong dark- grey swelling, with the posterior extremity of which the Vidian nerve is united, while its an- terior is attached to the naso-palatine nerve. The author, therefore, concurs in the opinion of Cruveilhier, so far as to regard the nerves con- nected with the ganglion, for the greater part, as branches of the fifth nerve and not of the ganglion; but he would exclude from this view the Vidian nerve, or at least its carotidean branch, which appears to him to belong to the sympathetic system. (See posterior branch of ganglion.) The disposition of this ganglion throughout the animal series is an object of interest. The author cannot assert its existence in the mam- malia universally, but from indirect considera- tions it appears to him likely that it does exist; generally at least, in animals of that class. It is asserted in the work* of Desmoulins and Majendie on the Anatomy of the Nervous Sys- tem in vertebrate Animals, that " there does not exist any trace of it in cats, dogs, the rumi- nantia, the rodentia, the horse, &c. ;" and it is reasonable to infer that they had found it in others. Now their statement with regard to * Mem. de l'Acad. de Berlin, 1794, * Tom, ii. p. 396, 286 FIFTH PAIR OF NERVES. its absence is, in the majority of the instances which they have selected, positively incorrect, for the author has ascertained its existence most satisfactorily in the dog, the horse, the cat, the cow, and the rabbit. Nor is any ex- ception to its existence mentioned by Cuvier, and hence he thinks it likely that it does exist generally, if not universally, throughout the class. It is not however similarly disposed in all ; in some it is connected with the primitive naso-palatine nerve ; in others with its nasal ; and in others again with its palatine division : in some it gives off few filaments ; in others, the horse, e. g. they are numerous beyond de- scription. The ganglion does not appear to exist in the inferior classes. From the spheno-palatine ganglion or nerve, according to the view of their source adopted, there is given off a considerable number of branches, which run in different directions and have different destinations: they have been distinguished into four sets, viz. superior, infe- rior, internal, and posterior. The superior branches are very delicate and, in some in- stances at least, numerous. Among them are described and represented by Arnold two long slender filaments, which join the optic : ano- ther is also mentioned by him to be sometimes found connected with the ophthalmic ganglion. The discovery of this connection between the two ganglia is due to Tiedemann, who found, upon the left side of a man, an anastomosis between them, established by a filament, of tolerable size, which, arising from the inner face of the spheno-palatine, entered the orbit and passing above the inferior branch of the motor- oculi nerve, where it gives off the short root, went in company with the last to gain the in- ferior and posterior part of the ophthalmic gan- glion ;* and beside those there may be found, in favourable subjects, others, which seem destined to the posterior ethmoidal cells. The inferior branch is the largest given off by the ganglion; it is distributed principally to the palate, and hence is called " the palatine ;" but it supplies the nostril also in part, and hence it has been suggested by J. F. Meckel, that it might be appropriately called the " naso-palatine :" this appellation has, however, been applied by Scarpa to one of the internal branches, and it has been already explained that it belongs more properly to the original branch before its junction with the ganglion. The palatine nerve descends from the ganglion into the spheno-maxillary fossa, posterior to the internal maxillary artery and toward the pterygo-palatine canals, and after a short course divides into three branches ; an anterior, larger one, denominated " the great palatine," and two posterior smaller branches, " the lesser palatine nerves." These branches continue to descend in com- pany until they reach the superior apertures of the canals ; they then enter the canals and are transmitted downward through them to the palate and fauces. The great palatine descends through the anterior pterygo-palatine canal, * Journal Compl. vol. xxiv. Arnold. in company with a branch of the palatine artery, at the same time inclining forward : during its descent it gives off, in some in- stances before, in others after it has entered the canal, either one or two filaments, which descend inward, pass through the nasal process of the palate bone, and enter the nostril at the back part of the middle meatus, between the posterior extremities of the middle and in- ferior turbinate bones : one of them is dis- tributed to the membrane of the middle bone and of the middle meatus ; the other to that of the convex surface of the inferior bone : when a single branch arises from the palatine it divides into two, which follow a similar distribution ; these branches are denominated by the elder Meckel inferior nasal nerves in con- tradistinction to the superior nasal, to be de- scribed, given off by the ganglion and by the Vidian nerve. Another filament is described by Cloquet arising from the palatine shortly before it escapes from the canal, entering the nostril through the perpendicular plate of the palate bone, running along the margin of the inferior turbinate bone, and lost upon the ascending process of the superior maxillary bone, often also contained in an osseous canal. The great palatine nerve, then, for the most part divides into three branches, of which one, the smallest, descends through an accessory canal, in the pterygoid process of the palate- bone, leading from the anterior, and escapes from it inferiorly into the soft palate in which it is consumed. The other two escape from the pterygo- palatine canal, through the posterior palatine foramen, into the palate : at emerging from the foramen they are situate very far back, in the posterior angle of the hard palate on either side, and behind the last molar tooth of the upper jaw; they are immediately super- ficial to the periosteum, and above the other structures of the palate ; they are lodged, along with the branches of the accompanying artery, in channels upon the inferior surface of the palatine processes of the palate and the superior maxillary bones; they pass forward, one along the alveolar arch, the other toward the middle line of the palate, and subdivide, each, into several branches, which are dis- tributed to the structures of the hard palate, the mucous glands and membrane, and to the gums, and communicate in front with branches of the naso-palatine ganglion. In some instances the palatine nerve does not divide into those ultimate branches until after it has escaped from the palatine canal ; but their disposition in such cases is in other respects the same. The lesser palatine nerves are posterior to the greater ; they are transmitted also through the pterygo-palatine canals, the first through the posterior, the second through the external. The first, the larger of the two, and called middle palatine nerve, escapes from the canal inferiorly in front of the hamular process of the sphenoid bone, and divides into filaments, which are distributed to the soft paiate and its muscles. FIFTH PAIR OF NERVES. The second, the posterior, little palatine nerve, descends at first between the external pterygoid muscle and the posterior wall of the antrum, then enters the canal, and escapes inferiorly external to the former ; it divides into two filaments, one of which is distributed to the soft palate, the other to the tonsils and arches of the palate. Those branches are accompanied by minute branches of the palatine artery. The internal branches vary in number from three to five; they arise from the inner surface of the ganglion, run directly inward, posterior to the nasal branch of the internal maxillary artery, toward the spheno-palatine foramen, which they immediately reach ; pass through the foramen, perforating the structure by which it is closed, and enter the nostril, and thus attach the ganglion closely to the foramen : at their entrance into the nostril they are situate before and beneath the anterior wall of the sphenoidal sinus, at the back part of the su- perior meatus, and immediately above the posterior extremity of the middle turbinate bone. They are distinguishable, according to the majority of descriptions, into two sets; one destined to the outer wall of the nostril and denominated by Meckel anterior superior nasal, in contradistinction to branches of the Vidian nerve, which he has designated " posterior superior nasal," and another con- nected with the septum. A third destination has been assigned to them by Arnold, accord- ing to whom a branch derived either from one of the nerves of the septum, or originally from the ganglion itself, is distributed to the supe- rior part of the pharynx, corresponding to the pharyngeal branch of Bock. The anterior superior nasal branches are either one or two in number ; when but one, it divides into branches corresponding to the two; it is so expressed in Arnold's fifth plate ; one of the two divides into filaments, which are distributed to the posterior ethmoidal cells, to the posterior part of the superior turbinate bone, and to the superior meatus, to the mem- brane of those parts. The second distributes its filaments to the convex surface of the mid- dle turbinate bone; according to Cloquet they in part perforate the bone, and thus gain its concave surface : they all run between the periosteum and the mucous membrane, and are distributed finally to the latter. The branches connected with the septum are two, a short and a long one ; they both pass across the anterior wall of the sphenoidal sinus from without inward, and thus reach the posterior part of the septum nasi, become attached to it, and changing their direction descend forward along it, between the perios- teum and mucous membrane. The short, lesser, branch is situate very near to the posterior margin of the septum, to which it is parallel in its course, and distri- butes its filaments to the membrane of the posterior part of it : one of them is repre- sented by Arnold as constituting the pharyn- geal branch. The long branch descends to the superior aperture of the anterior palatine canal, enters the canal, and in it the nerves of the two sides are united to a small ganglion denominated the naso -palatine ; from it filaments descend to the anterior part of the palate, in which they are distributed and communicate with filaments of the palatine nerves. Each nerve, during its course along the septum, is situate nearer to its position inferior than to its supe- rior anterior margins : it is said not to give any filaments during its descent, but this is incorrect, as is well represented by Arnold ; those, which it gives off, are distributed to the membrane of the septum about its middle; at times also it divides into two filaments, which are afterwards reunited. Each nerve is received inferiorly in a separate canal, which inclining inward is soon united to the other in the palatine, and in it the nerve or the naso-palatine ganglion receives a filament of communication from the anterior superior den- tal branch of the second division of the fifth, as described by Cloquet. This branch has been particularly described, first by Scarpa,* and by him denominated the naso-palatine ; it has been also described by J. Hunter,-}- between whom and Scarpa appears to lie the merit of having first ob- served it ; it is also known as " the nerve of the septum," but the latter appellation is ma- nifestly incorrect; nor is the former free from objection, inasmuch as the same title has been applied, and with reason, in the inferior Mam- malia, to the original branch given off by the second division of the fifth for the supply of the nostril and palate, with which the spheno- palatine ganglion is connected, and which in man has received the name of spheno-palatine branch. The branch of the ganglion in ques- tion is called by some the nerve of Cotunnius, but incorrectly ; having been first described by Scarpa, it cannot with justice be attributed to the former. The posterior branch of the ganglion is de- scribed and represented by the majority of authorities as arising single and in its course dividing into two filaments; but Bock, J. F. Meckel, and Hirzel state that the two fila- ments at times are throughout distinct and connected separately to the ganglion; and Arnold represents, in like manner, two fila- ments arising from the ganglion, corresponding to the two into which the single nerve divides. The posterior branch arises from the back of the ganglion, passes directly backward from it, and is received immediately into the pterygoid or Vidian canal, along with the corresponding branch of the internal maxillary artery : it is transmitted through the canal backward and slightly outward, beneath the course of the second division of the fifth itself, and external to, or in many instances beneath the sphenoidal sinus ; having traversed the canal, * Annotationes Academics, in which is also con- tained a good representation of the nerve as a single branch. t Animal (Economy. 288 FIFTH PAIR OF NERVES. it escapes from its posterior aperture into the foramen lacerum anterius basis cranii : in this it is contained in the fibrous structure by which the foramen is closed, and is situate at the outer side of and beneath the internal carotid artery, as that vessel ascends, from the aperture of its canal in the petrous bone, into the cavernous sinus. Here also, or even before it has escaped from the Vidian canal, it receives, when single, a filament of com- munication from the superior cervical ganglion of the sympathetic : this filament had been long regarded as arising from the posterior branch itself, and — though at present gene- rally* considered a branch from the sympa- thetic— it has been for the most part described, in systematic works, as such under the name of the inferior, deep, sympathic, or carotidean branch of the Vidian nerve. In its direction it certainly resembles a branch of that nerve ; but in that particular it is equally entitled to be regarded one from the sympathetic to the spheno-palatine ganglion, it being either from before backward and from above downward, or from behind forward and from below up- ward. Further, in sensible qualities it strictly resembles other branches of the latter nerve ; it is, as has been stated, at times separate from the proper Vidian, and connected directly with the spheno-palatine ganglion ; and it is, in fact, but one of the branches which ascend into the cranium from the superior cervical ganglion along the internal carotid artery, so that it would be equally correct to describe that fila- ment which is connected with the sixth nerve as a branch of that nerve, as to style the fila- ment in question a branch of the Vidian nerve. The view of the nature of this filament here advanced is, however, not universally admitted. Cruveilhier objects to it because the cranial branch of the Vidian nerve appears to him to resemble in all respects the carotidean : this, however, cannot be considered a valid objec- tion, it can only prove that one branch may be as much allied to the ganglionic system as the other, but the validity of the assertion may be questioned ; however it may be in man, the characters of the two branches in the larger quadrupeds, the horse e. g. are sufficiently distinct, the cranial branch being of a pure white colour, and the carotidean having a gan- glionic enlargement upon it at its junction with the cranial. While traversing the pterygoid canal, soon after it has entered that canal, and in some cases even before, the posterior branch of the gan- glion gives ofF from its inner side two or three filaments, denominated by the elder Meckel posterior superior nasal : these enter the poste- rior superior part of the nostril, in one case by passing through the spheno-palatine foramen, in the other by perforating the inner wall of the pterygoid canal, and are distributed to the posterior part of the lateral wall of the nostril, to the root of the septum, to the sphenoidal sinus and to the lateral wall of the pharynx in the vicinity of the orifice of the Eustachian Bock, Cloquet, Hirzel, J. F. Meckel. tube. These branches frequently arise from the ganglion itself by a single filament, de- nominated by Bock the pharyngeal nerve, and represented by Arnold among die internal branches of the ganglion : it divides into fila- ments distributed to the several parts men- tioned. After the junction of the sympathetic fila- ment, the posterior branch is continued through the fibrous structure already mentioned, ex- ternal to the internal carotid artery, and thus enters the cranium. It then passes out- ward, backward, and upward, upon the ante- rior surface of the petrous bone, beneath the third division of the fifth, very near its attachment to the Gasserian ganglion, and enclosed in the dura mater : it is at the same time lodged in a channel upon the sur- face of the bone. It is stated by Cloquet that it here sends into the cavity of the tympanum by two canals, the orifices of which are to be seen in the channel one above the other, two filaments of extreme delicacy, which go to anastomose together upon the promontory, and to communicate with a filament of the supe- rior cervical ganglion, and with the glosso- pharyngeal nerve. According to Hirzel,* this connection between the superficial branch of the Vidian and the tympanic branch of the glosso-pharyngeal nerve on the nerve of Jacob- son, takes place in the vicinity of the junction of the former with the facial nerve. Accord- ing to Arnold,f the superficial branch of the Vidian nerve is, as proved by the researches of others and his own, not simple, but composed of two or of several filaments, and is accom- panied by one or more very delicate filaments from the carotid plexus. In one instance he found the petrous nerve composed of four filaments on the right, and three on the left. The existence of several distinct filaments in the Vidian nerve may be easily observed in the larger animals. It pursues the course men- tioned, until it has reached the hiatus Fallopii, through which it is transmitted to the aqueduct of Fallopius, where it meets and becomes in- timately connected with the facial portio dura nerve. At their junction the facial nerve pre- sents a gangliform swelling, from which two very delicate filaments proceed to the auditory nerve. J From the time that the posterior branch of the ganglion enters the cranium until it has joined the facial nerve, it is called the cranial or superficial petrous branch of the Vidian nerve ; by Arnold petrosus superficialis major in contradistinction to another nervous filament, which connects his ' otic' ganglion to the tym- panic branch of the glosso-pharyngeal nerve ; but the application of either of these epithets would be rendered unnecessary by ceasing to consider the filament by which the posterior branch of the ganglion is connected to the sympathetic, a branch of the former. The posterior branch is also known by other * Journ. Corapl. t. xxii. + Journ. Compl. t. xxiv. % Arnold. See lingual branch of third division and chorda tympani. j1> ()?■ FIFTH PAIR OF NERVES. 289 names, viz. the recurrent, the pterygoid, the Vidian, the anastomotic, or sympathies. 3. The next branch or branches of the su- perior maxillary nerve are the posterior supe- rior dental. These arise from the nerve in front of the internal maxillary artery, between it and the back of the antrum, and are sepa- rated from the artery by the spheno-palatine ; they are very irregular as to their number and precise place of origin ; at times there is but one branch, at others there are two or three : they are distributed to the buccinator muscle and the mucous membrane of the posterior lateral part of the mouth, to the roots of the posterior teeth, the membrane of the maxil- lary antrum, and the gum of the upper jaw. When but one branch is present, its sub- divisions supply the place of the others. It descends into the fossa, behind the superior maxillary bone, and before the internal maxil- lary artery, and after a certain way divides into two branches or sets of branches, posterior and anterior. The posterior consists of several long slen- der filaments, which continue to descend im- mersed in the fat of the zygomatic fossa, until they reach the surface of the buccinator muscle; they then in part are distributed to it, but in greater number pass between the fibres of the muscle and are lost in the mucous membrane of the mouth. The anterior branch descends for some time, until it reaches the back of the maxilla; it then enters a canal in the bone, within which it is transmitted forward through the wall of the antrum ; after a short way it escapes from the canal and continues its course forward within the wall, between it and the lining membrane, describing a curve convex down- ward ; having reached the front of the antrum it ascends and terminates by joining either the anterior superior dental or a branch of that nerve. During its course around the antrum the anterior branch of the nerve gives off down- ward numerous delicate filaments, which de- scend toward the teeth, traverse the structure of the alveolar arch, and in part are distributed to the roots of the posterior superior teeth in a manner analogous to that of the inferior dental nerves : in part they escape inferiorly from the alveolar arch between the sockets of the teeth, and are consumed in the gums. The nerve is also stated to give filaments to the membrane of the maxillary antrum. 4. Shortly before its escape from the infra- orbital canal, but at a distance somewhat variable from it, the second division of the fifth gives oft" its next regular branch, the anterior superior dental : this descends, from tbe infraorbital canal, through one of its own name in the anterior wall of the antrum to- ward the canine tooth ; it next runs inward above the root of that tooth, and then again descends through the perpendicular process of the maxillary bone, until it reaches the floor of the nostril, and is continued inward through the horizontal process of the bone above the roots of the incisor teeth. VOL. II. While descending through the wall of the antrum the anterior superior dental nerve either is joined by the termination of the anterior branch of the posterior dental, or it divides into two, one of which inclines outward and joins that branch, the other pursues the course of the nerve. It supplies the anterior teeth of the upper jaw in the same manner as the pos- terior nerve does the posterior teeth ; it also gives at its termination filaments to the mem- brane of the nostril, and one to the naso- palatine ganglion or nerve. Besides the regular dental nerves, others at times arise from the second division of the fifth within the infraorbital canal, and take the place of branches of the regular nerves. 5. The facial brandies of the second division of the fifth are from five to seven in number ; they differ from each other in size, and branch off in different directions; they are distin- guished, according to the direction in which they run and their destination, into three sets; a superior or palpebral, an inferior or labial, and an internal or nasal. For the most part there is but one superior or palpebral branch, though sometimes there are two. This branch is destined to supply the lower eyelid, and is denominated the inferior palpebral nerve ; it presents some variety in its mode of origin and its course ; most frequently it does not separate from the trunk till after the latter has escaped from the infraorbital foramen; but in some instances it does so within the in- fraorbital canal, is transmitted through a dis- tinct canal, and escapes into the face through a separate foramen, situate internal to the infra- orbital ; it ascends inward toward the lower lid, in front of the inferior margin of the orbit ; in its ascent it is situate beneath the orbicularis palpebrarum, to which it gives filaments, which after supplying the muscle become cutaneous, and it is frequently contained in a superficial groove on the superior maxilla ; having reached the lid it divides into two branches, an external and an internal. The external runs outward, through the lid, toward the external angle, supplies its structures on that side, and anasto- moses with filaments of the portio dura, and of the inferior palpebral branches of the lachrymal nerve. The internal ascends in the course of the original nerve toward the internal canthus of the eye, gives a filament to the side of the nose, which communicates with the naso-lobar branch of the nasal nerve, supplies the lower lid at its internal part, is also distributed to the carun- cula and lachrymal sac, and anastomoses with a filament of the inferior branch of the infra- trochlear nerve described in the account of that nerve. It sometimes anastomoses also with the portio dura. When there is a second palpebral branch, it takes the place of the external branch of the former, which in such case is denominated the internal inferior palpebral, and the second the external. It perforates the levator labii supe- rioris muscle ; ascends toward the external angle of the eye, beneath the orbicularis palpe- brarum ; and, like the external branch of the inferior palpebral, already described, supplies u 290 FIFTH PAIR OF NERVES. the structure of the lid, and anastomoses with the portio dura, lachrymal, and malar nerves, as also with the internal palpebral. The descending or labial branches are the largest and the most numerous ; for the most part they are three, at times four. They de- scend to the upper lip, one toward its middle, the second toward its intermediate, and the third toward its outer part, the commissure of the lips, and are denominated internal, mid- dle, and external; they are situate, all at first, beneath the levator labii superioris, between it and the levator anguli oris or canine muscle; as they descend, they give filaments to these muscles and to the parts superficial to them ; and they pass to their several destinations, the internal between the levator labii and the de- pressor alas nasi ; the middle between the same muscles ; and the external superficial to the levator anguli, and uncovered by the levator labii ; as they approach the lip they divide each into branches, which are distributed to the structures of the part at their several situa- tions ; to the orbicularis oris, and the insertions of the other muscles of the lip, to the integu- ment of the lip, internal and external, and also to the labial glands ; they all communicate to- gether, and with branches of the portio dura ; the external more particularly with the latter, as also with the neighbouring branches of the fifth ; the internal with the inferior nasal ; the external with the inferior labial and buccal nerves. In the infraorbital region, the branches of the superior maxillary are crossed by and interlaced with those of the portio dura; the latter running from without inward, and for the most part superficial to the former ; but also beneath and among them, and even forming loops about them ; while the former run from above downward, and are principally deeply seated. In consequence of this diversity in their directions and the numerous anastomoses which they hold with each other, the branches of the two nerves form a very intricate mesh in that region. In some Carnivora filaments of the facial branches of the fifth nerve have been traced into the bulbs of the hairs of the whiskers and the tufts with which they are furnished ; this is remarkably so in the seal, as described by Andral : they are strongly expressed by Rapp.* The internal or nasal branches are, for the most part, two ; they are termed superficial nasal by the elder Meckel, and distinguished into supe- rior and inferior; they pass, both, inward toward the nose, beneath the levator labii superioris, the inferior at the same time descending, and having reached the side of the nostril they sub- divide. The superior is the smaller of the two,, and arises frequently from a branch common to it and the internal inferior palpebral ; it divides into three, of which the first, the uppermost, is distributed to the origin of the levator labii alaeque nasi, to the compressor naris, and to the integuments on the dorsum of the nose; the * Die Verrichtungen des funften Hirnnerven- paars. second, the middle, to the compressor naris and also to the integuments of the nostril, and the third, the inferior, to the compressor naris, to the depressor alae nasi, and to the integu- ments of the ala. The inferior superficial nasal, the larger of the two, first gives occasionally a branch, which ascends to the eyelid ; then communicates with the superior, and having reached the ala of the nose, it gives off numerous ramifications which are distributed to the levator and depressor alae, to the integuments of the inferior part of the ala, of the tip, and of the septum, and also to the upper lip ; it communicates with the rami- fications of the naso-lobar branch of the nasal nerve, of the internal labial, and of the portio dura. The third division of the fifth. — This trunk has been denominated by Winslow, on account of its general distribution, the inferior maxillary nerve, and it is generally known by that appel- lation ; yet it appears to the writer that it would have been much better had that title been applied only to that portion of the nerve which enters the lower jaw. Such is the opinion of the elder Meckel, who observes that this use of the epithet leads to the inconveni- ence that the branch alluded to and the trunk of the nerve may be easily confounded. It is much the largest of the three divisions, and differs remarkably from the other two in its composition ; they are both single, and derived altogether from the Gasserian ganglion; it on the contrary is composed and made up of two portions, one derived from the ganglion, the other not connected with it ; the former is the largest of the three trunks connected with the ganglion ; it is attached to its posterior external extremity ; at its attachment it is cineritious and very wide, but as it proceeds it loses that tint, and acquires a compressed cylindrical form. It is situate external, posterior, and in- ferior to the others, and its course within the cranium is very short or none, for from the ganglion it enters at once the inferior maxillary or foramen ovale of the sphenoid bone, and escapes from the cavity, passing downward, for- ward, and outward, nearly at right angles with the second division of the fifth. Before leaving the cranium it is joined, as the first and second divisions are, by a filament from the sympa- thetic, according to Munniks, Laumonier, and Bock* The second portion, of which the third division is composed, is , the lesser packet of the fifth itself; this, it has been already stated, does not join the ganglion, but passing out- ward, beneath that body, is united to the former portion posteriorly, in the foramen ovale ; it forms, however, but a small proportion of the nerve, that part which is attached to the gan- glion exceeding it very much in size. At its junction, it is placed posterior to the other, but it immediately spreads out, and increases very much in width, and at the same time is lapped round the inner side of the ganglionic portion so as to get before it, and to form the * Op. cit. and Journ. Compl. FIFTH PAIR OF NERVES. 291 anterior part of the nerve by the time it has escaped from the cranium. The third division of the fifth nerve, after its escape from the cranium, is situate in the superior, posterior, and internal part of the zygomatic fossa; it is placed immediately be- hind the external pterygoid muscle, before and somewhat internal to the styloid process of the sphenoid bone, internal to and on a line with the anterior margin of the temporo-maxillary articulation, and external to the Eustachian tube. So soon as the inferior maxillary nerve has entered the fossa, it gives off, immediately beneath the superior wall of that fossa, a set of branches remarkable for their source and destination ; they proceed from the front of the nerve ; their regular number is five, but they present variety in this respect, being in some instances not so many at their origin, in others amounting to six ; they vary also in the mode in which they arise ; for the most part they are given off separately and branch off, as rays, from the nerve, but at times the nerve divides into two branches, a smaller anterior one, and a larger posterior; in such case the anterior divides immediately into the branches, which otherwise arise from the nerve itself. These branches are the masseteric, the deep temporals, the buccal, and the pterygoid nerves, and they are ranged in succession from behind forward, and from without inward ; the first is external and posterior; to it succeed the tempo- rals, then the buccal, and lastly the pterygoid. 1 . The masseteric branch proceeds from the anteriorand outer part of the nerve; it passes out- ward, nearly transversely, beneath the superior wall of the temporal fossa, and in front of the articular surface of the temporal bone ; it crosses obliquely over the external pterygoid muscle, at its outer extremity, between the muscle and the wall of the fossa, and then inclines down- ward through the sigmoid notch of the lower jaw, in front of its neck, and of the insertion of the external pterygoid muscle, and posterior to the coronoid process and the tendon of the temporal muscle. Having traversed the notch it descends forward, external to the ramus of the jaw, and passing between the two portions of the masseter, divides into numerous ramifica- tions, which are distributed altogether to that muscle : while between the portions of the masseter, it inclines from its posterior toward its anterior margin, and its terminating filament can be traced to the latter at the inferior part of the muscle. This branch gives off, during its course, some minor branches ; while in front of the articulation of the jaw it gives one or more filaments to the articulation ; in the next place it gives a small branch to the posterior part of the temporal muscle, and lastly it fre- quently gives off the external or posterior deep temporal nerve. 2. The deep temporal branches are two; they are distinguished into posterior and anterior or external and internal. The anterior is the larger. They present varieties in their num- ber and mode of origin ; at times there is but one, at others there are three ; in some instances they arise by a common origin ; in others, and for the most part, separately, and in others again the posterior or lesser branch is given off either by the masseteric or the buccal nerve. They both pass outward, in front of the tem- poro-maxillary articulation, between the exter- nal pterygoid muscle and the superior wall of the zygomatic fossa; they then change their direction and ascend in the temporal fossa, be- tween the muscle and the surface of the fossa, and divide into branches, which attach them- selves to the temporal muscle, on its deep sur- face, and are distributed, those of the posterior to its posterior, and those of the anterior to its middle and anterior parts. The two branches frequently anastomose with each other as they leave the zygomatic fossa. The anterior also frequently communicates with or receives a branch from the buccal nerve, and by one of its anterior filaments it anastomoses with the nerve resulting from the junction of the tempo- ral branches of the lachrymal nerve and the temporo-malar branch of the second division of the fifth. This communication between the three divisions of the fifth is however, accord- ing to the elder Meckel, subject to variety; he states that he has seen the communicating branch of the anterior deep temporal at times enter the orbit either through the malar bone, or through the spheno-maxillary fissure, and there unite with the conjoined branch of the other two. 3. The buccal nerve is the largest and the principal of these branches ; it arises from the front of the inferior maxillary nerve, next in or- der after the anterior deep temporal, for the most part a distinct and single branch ; but it is not unusual to find the buccal nerve give off one or both of the deep temporals, or in rare cases all the three former branches : in some instances also it arises double, the two filaments, of. which it is then composed, being separated by a portion of the external pterygoid muscle. It runs downward and forward, passing at first either and for the most part through the exter- nal or between the two pterygoid muscles, be- neath the .external and external to the internal; having traversed the pterygoid it descends in front of its inferior part, internal to the coronoid process of the lower jaw, and the inferior part of the temporal muscle, next between the ten- don of the temporal and the buccinator, then between the anterior margin of the masseter and the latter muscle, and finally emerging from between them it inclines toward the angle of the mouth, superficial to the buccinator and beneath the dense expansion by which that muscle is covered. During its descent it is immersed in the fat which occupies the lower part of the zygomatic fossa. The ramifications which it gives off are numerous; first while traversing and immediately after escaping from the pterygoid it gives branches to the muscle ; at the same time it gives off a fasciculus of branches which pass outward, in front of the external pterygoid to the internal surface of the temporal muscle, at its inferior part ; some of these descend with the muscle v 2 292 FIFTH PAIR OF NERVES. toward its insertion, and are distributed to it at that point, others ascend in the temporal fossa, between the muscle and the bone, penetrate the muscle, and are distributed, along with the branches of the anterior deep temporal, with which they anastomose freely, to the muscle at its inferior anterior part. In the next place, while between the masseter and the buccinator, the nerve gives off backward several branches, three or four, which are distributed to the buc- cinator at its origin, to the buccal glands, and to the membrane of the mouth ; as it lies upon the last-named muscle, between the ramus of the jaw and the angle of the mouth, it gives filaments to it at its middle and anterior part, which, like the former, both supply the muscle, pass through its fibres, and are distributed also to the buccal glands and membrane. Finally, as the nerve approaches the angle of the mouth, it divides into two, occasionally three, branches; these two branches pursue the direction of the nerve toward the angle, passing beneath the facial vein and inclining, one upward, the other downward; after a short course they are united both to branches of the portio dura, the inferior to a branch of the inferior or cervico-facial divi- sion, the superior to one of the superior or tem- poro-facial division of that nerve. By their union they form conjoined branches or loops, from each of which are given off several fila- ments to the muscles of the mouth at their in- sertion into the angle ; from the superior, more particularly, to the buccinator, the zygomatic, and levator anguli ; and from the inferior to the buccinator and depressor anguli oris. 4. The fifth and last of these branches is the pterygoid; it is the smallest of them, and arises from the anterior internal part of the trunk ; it passes inward and downward, be- hind the external pterygoid, and then between the internal pterygoid and circumtlexus palati muscles ; it gives a filament of some size to the latter muscle, and then entering into the internal pterygoid at its upper extremity, it is consumed altogether in that muscle. The external pterygoid also, at times, but not uniformly, receives a distinct filament from the trunk ; when present it arises from the front of the nerve, beneath the buccal branch, and passes forward directly to the muscle, in which it is consumed. The constitution of these branches is peculiar, and is a matter of much interest: involving physiological ques- tions, this subject is deferred to another oc- casion. In consequence of its connection with the third division of the fifth, and more particularly with the lesser packet of the nerve, this seems a fit place to advert to the ganglion discovered by Arnold, and by him denominated Otic or auricular, of which the following sketch has been taken from his own account. It is situate at the inner side of the third branch of the fifth, some lines beneath the foramen ovale, at the part where the deep temporal, the masseteric, and the buccal nerves are de- tached from the same side, and a little above the origin of the superficial temporal nerve : its posterior part touches the middle meningeal artery, and the internal the internal pterygoid muscle : an abundant adipose tissue surrounds it : its form is not altogether regular, however it approaches to an oval, flattened internally and externally. It is united to the trunk of the third division not merely by cellular tissue, but by many filaments, which enter into the formation of the ganglion ; these filaments, which come solely from the lesser portion of the nerve, are mostly extremely short, and can only be observed when we try to separate the ganglion from the trunk ; but in cases where the ganglion is situate rather distant from the nerve, the filaments are of course longer and can be more easily observed. With regard to the branches of the third division, the pterygoid nerve espe- cially is in very intimate connection with the otic ganglion, so that in a superficial examina- tion it appears as if it arose from it ; but, in a more accurate investigation, it is clear that this nerve soon after its origin penetrates through a part of the substance of the ganglion and takes up some of it : the slender branch, which ramifies in the tensor palati, is likewise in very intimate relation with this ganglion, and distinguishes itself from the other branches by its reddish appearance. The ganglion thus communicates with the lesser packet of the fifth : it also communicates with the glosso- pharyngeal and with the facial and auditory nerves by means of the nervus tympanicus. But, the ganglion being a body which is to be regarded as distinct from the fifth nerve, and not part of it, a further pursuit of its connections and properties would be here out of place. See Svmpathetic Nerve. The third division of the fifth descends from the foramen ovale, outward into the zygomatic fossa, posterior to the external pterygoid muscle, before the superior part of the levator palati, and internal and parallel to the middle me- ningeal artery. After a course of half an inch from the foramen, it divides for tiie most part into two large branches, an anterior internal one destined to the tongue, denominated the Ungual branch, and an external posterior one, which is transmitted through the inferior max- illary canal, and, escaping from this, through the mental foramen, is distributed finally to the muscles and integuments of the chin ; this second branch is called inferior dental, or inferior maxillary nerve ; the latter, as has been already intimated, appears much the more appropriate appellation. The first branch bears, very generally, the name of gustatory nerve from its presumed connection with the sense of taste; but, since the opinion that it is the nerve in which the sense of taste resides has been brought into question, and since, as will appear by-and- bye, it is at least certainly not the sole nerve of that sense, it is obvious that that name should be discontinued. The manner in which the third division finally divides is not always such as has been described : in some instances it separates fairly FIFTH PAIR OF NERVES. 293 into three branches, viz. the lingual, the inferior maxillary, and the superficial temporal, and such is the mode of division mentioned by the elder Meckel. The writer has before him an instance of another mode ; the inferior maxillary arises by two roots, and the' original trunk divides into two parts; one common to the lingual, and one root of the maxillary ; the other to the superficial temporal and the other root : the superficial temporal is thus, in this instance, equally an original branch as the others, and is connected to the maxillary by a filament, which it gives off soon after its origin, while the maxillary is also connected in the usual mode to the lingual : the maxillary artery, however, passes through the loop formed by the two roots of the former nerve. The length of the third division from the ganglion to its bifurcation is about three fourths of an inch, one fourth contained within the bone during its escape from the cranium, and the other two between the aperture externally and the division. When it divides into two, the branches are, at times, of the same size, but for the most part the inferior maxillary is the larger; they descend at first in close apposition with each other, but as they proceed they gradually separate, the lingual branch inclining inward and forward, the inferior maxillary outward, in the course of the original nerve, in order to gain the aperture of the dental canal ; they thus leave between them an angular interval, acute above, through which the internal maxillary artery for the most part passes. In their descent they cross, at right angles, the artery internal to the origin of the middle meningeal branch : in doing so either they pass both behind the vessel, or the lingual branch passes before, and the inferior maxillary behind it. The two nerves are most frequently connected, soon after their origin, by a short and delicate branch, which passes from the inferior maxillary to the lingual, and forms, with the nerves, a triangle, through which the artery passes in those instances in which the lingual descends before it. The nerves are situate internal to the neck and ramus of the jaw, between the pterygoid muscles, posterior and inferior to the external, external and anterior to the internal ; and they are contained in a triangular space included between the two muscles and the jaw, bounded superiorly by the external, beneath and in- ternally by the internal pterygoid, and externally by the jaw; through this space they pass from above downward, the lingual from behind forward, and from without inward, the maxil- lary from within outward, toward the aperture of the dental canal, and holding the mutual relation already indicated, — the lingual anterior and internal, the maxillary posterior and ex- ternal. Before pursuing these branches of the third division further, it will be well to describe the superficial temporal nerve. This branch has been viewed differently by different autho- rities ; by some it is accounted one of the former set, the superior anterior branches of the third division ; by Meckel it is described as one of three, into which the continuation of the nerve divides. It arises for the most part by two, and in some instances by three, roots ; a larger one from the inferior dental nerve, and a smaller from the trunk of the third division itself, given off at the same time with its superior branches, and deri- ved from the same source; the two roots forming together a loop, through which the middle meningeal artery ascends: in conse- quence of this mode of origin it appears better to describe it thus separately, and not to refer it to either of the sets described. It has, however, been already explained that in some cases it appears to be an original branch of the third division, one of three into which it finally divides. The nerve runs outward, backward, and somewhat upward, behind the external ptery- goid muscle, toward the back of the neck of the lower jaw ; it then passes behind it and the condyle, between them and the auditory canal, traversing the posterior part of the glenoidal cavity of the temporal bone, and imbedded in the process of the parotid gland, which occupies it. The superficial temporal nerve, while within the ramus of the jaw, pursues a course nearly the reverse of that of the trunk of the internal maxillary artery in the first part of its course. At first it is situate before the tensor palati muscle, between it and the external pterygoid ; then it passes between the internal lateral ligament of the maxillary articulation and the neck of the jaw, situate at the same time above and in contact with the artery ; and lastly, it is situate behind the condyle of the jaw, between it and the meatus auditorius, and involved in the parotid. The nerve gives off numerous branches ; when it has reached the situation last described, it breaks up at once into a leash of branches, which pass off in different directions : of these two, at times only one, are destined for the interior of the meatus auditorius ; they ascend toward the canal, become attached to its ex- terior, and pass through the fibrous structure of the tube, close to its connection with the osseous portion : having thus gained its interior, they are distributed to its lining membrane, its sebaceous follicles, and the membrane of the tympanum. Before entering the tube they give some delicate filaments to its exterior; these branches may be called the internal auricular. Others, the smallest which the nerve gives off, descend along the external carotid artery, are in part distributed to the parotid gland, and establish upon the artery a manifest com- munication with branches of the sympathetic. Its next branches, two in number, pass out- ward through the substance of the parotid, behind the neck of the jaw; one external or superficial, the other internal to the temporal artery; and turning forward round the posterior margin of the jaw, either they both, having given some fine ramifications to the gland, join the temporo-facial branch of the portio dura, immediately before its division, or one of them joins the facial branch of the tern- 294 FIFTH PAIR OF NERVES. poro-facial, while the other continues forward, upon the face, below the zygoma, and deeper than the branches of the temporo-facial : it divides into numerous long filaments, of which some join both branches of the temporo-facial ; others are distributed superficially upon the side of the face beneath the zygoma and upon the malar region, and, ascending over the former part, to the inferior anterior part of the temple, as far forward as the margin of the orbit. These may be called the commu- nicating branches, in consequence of the re- markable and important communication which they establish with the portio dura. The next may be called external auricular ; they ascend to the anterior part of the car- tilaginous tube of the ear, concealed by the temporal artery, attach themselves to the tube in front, and are distributed to the integuments of the concha. Lastly, the superficial temporal nerve emerges from the parotid gland, beneath the root of the zygoma, between the condyle of the jaw and the cartilaginous tube of the ear, in company with the temporal artery, and concealed by it : it then changes its course and ascends with the artery behind the zygoma and in front of the ear, upon the temple : there it emerges from beneath the artery, posterior to it, and divides into branches, which become subcutaneous, run superficial to the fascia and the artery beneath the subcutaneous cellular structure, and are ultimately distributed to the integument of the temple : their number is two or three ; they may be distinguished into anterior, middle, and posterior, and they are destined to the corresponding parts of the temple : they correspond in their course, but by no means regularly or strictly so, to the branches of the temporal artery, from which they are separated by the fascia. Of the two terminal branches of the third division, the larger one, the inferior maxil- lary or dental, descends outward to the upper orifice of the inferior maxillary canal. In its course it passes always behind the inter- nal maxillary artery, and soon glides between the internal lateral ligament of the temporo- maxillary articulation, and the ramus of the jaw, descending in front of the anterior margin of the ligament, which thus becomes interposed between it and the lingual branch, and also be- tween it and the internal pterygoid muscle, from the pressure of which the ligament is considered to protect it. In that situation it is joined by the inferior dental artery, a branch of the internal maxillary given off between the ligament and the jaw, which accompanies it through its further course. It next enters the canal, and is trans- mitted through it downward, forward, and inward toward the chin, beneath the sockets of the teeth; having reached the termination of the canal, it is reflected upward and outward through the mental foramen, and escapes from the canal upon the lateral and superficial surface of the jaw, at either side of the chin; at its exit it is beneath the second bicuspid tooth of the lower jaw, and covered by the muscles of the lip : it then terminates by dividing into two branches, called inferior labial nerves, external and internal. The branches of the inferior maxillary are as follow : — presently after its origin it gives off the branch by which the lingual branch and the inferior maxillary are connected, and which completes the loop through which the internal maxillary artery passes ; also the branch which forms a root of the superficial temporal nerve. Next, imme- diately before entering the dental canal, it gives off a long slender branch, denominated mylo- hyoid nerve ; this branch descends forward and inward along the inside of the ramus of the jaw, between it and the internal pterygoid muscle, and lodged in a groove upon the sur- face of the bone, which leads in the same direction, and is occasionally in part a bony canal ; it is covered in the groove by a prolon- gation of the internal lateral ligament, and escapes from it inferiorly in front of the insertion of the internal pterygoid muscle and beneath the lingual branch; it then passes beneath or external to the mylohyoid muscle, between the submaxillary gland and the internal surface of the jaw, gains the surface of the muscle itself and runs forward and inward above the super- ficial portion of the gland, between it and the muscle, and accompanied by the submental artery; finally, it divides into a leash of branches. Of these one is sometimes destined to the sub- maxillary gland ; two or three are distributed to the mylohyoid muscle; another to the anterior belly of the digastric, and the last passes first between the anterior belly of the digastric and the mylohyoid, gives filaments to the muscles in its passage, then ascends upon the chin internal to the belly of the digastric, and is consumed in the depressor labii muscle. The next branches of the nerve are those which are given off by it while within the inferior maxillary canal : they have two desti- nations, viz. the roots and periosteum of the teeth and the gum of the lower jaw. During its course through the canal the nerve gives off several long, slender branches, which run for some distance within the canal, ascend thence through the bone beneath and on either side of the roots of the teeth, ramify as they proceed, and distribute their ramifications to the desti- nations which have been mentioned. The author has never found these branches as they are for the most part represented, viz. short single filaments ascending almost directly into the several fangs of the teeth : they are deci- dedly less remarkable and less numerous in the old subject after the fall of the teeth than in the young. Again, at the mental foramen, and immediately before its escape from the canal, the nerve gives off a more considerable branch, denominated by Cruveilhier dentaire incisif, which is continued through the jaw toward the symphysis beneath the canine and incisor teeth, and distributed to them. The former set supplies the posterior molar teeth. Accord- ing to the general opinion the nerves of the teeth enter the fangs through the apertures in their extremities, and are transmitted through them into the bodies of the teeth, to be con- sumed in the pulp and the structure of the FIFTH PAIR OF NERVES. 295 leeth themselves. J. Hunter, however, has stated in his work on the teeth, that he has never succeeded in tracing nerves into the fangs, and the experience of the writer, so far as it extends, tends to confinn the doubt thus ex- pressed; he has frequently traced the filaments to the structure at the root of the fang, but never into the fang, and in the jaw of the fcetal calf they may be found distributed in number upon the membrane of the pulp, but he has not been able to follow them into the pulp itself. The filaments sent into the gums from the dental nerves, superior as well as inferior, traverse the alveolar arch, escape from the bone upon its gingival aspect, and at once enter the gum : they are well represented by Arnold. The final branches of the inferior maxillary nerve are the inf erior labial, internal and exter- nal. Of these the internal is the larger; it ascends toward the mouth, inclining inward, and breaks up into a great number of ramifica- tions, which are distributed to the depressor labii inferioris, the depressor anguli oris, the orbicularis, and the levator menti, also to the integument and internal membrane of the lip, and to the labial glands; they anastomose with branches of the inferior division of the portio dura. The external inclines toward the angle of the mouth ; it also gives off a great number of ramifications, distributed to the depressor anguli, the orbicularis, and the insertion of the muscles at the angle, the integument, and internal membrane of the lip, and the labial glands; it also anastomoses with branches of the portio dura. The Ungual branch of the third division. — The situation and relative size and position of the lingual and inferior maxillary branches in the first part of their course, have been already described. Having crossed the internal maxil- lary artery, the lingual branch pursues its course downward, forward, and inward, passing first between the pterygoid muscles in the manner described, and then between the internal ptery- goid and the ramus of the jaw, until it has reached the anterior margin of that muscle; during this part of its course it is at first separated from the inferior maxillary nerve by the internal lateral ligament, which is placed between them, the lingual branch internal, the maxillary external to it, and afterward it is situate anterior and superior to the mylohyoid branch of the maxillary. Having reached the margin of the pterygoid it emerges from between the muscle and the jaw, immediately behind the posterior extremity of the mylohyoid ridge, and enters into the digastric or submaxillary space, in which it is among the parts most deeply situate; within this space it continues to run forward and inward, until, at the anterior extremity, it attaches itself to the under surface of the tongue, and is prolonged by one of its branches to the extremity of that organ. During its course through the digastric space, it is at first left uncovered by the muscles inferiorly, and in the interval between the margin of the pterygoid and that of the mylohyoid, where it is situate betwee» the mucous membrane of the mouth and the posterior extremity of the submaxillary gland ; it then passes internal to the mylohyoid muscle, between it and the stylo-glossus, hyo-glossus, and genio-glossus, and is at the same time contained in a triangu- lar or wedge-shaped space, the base of which is above and the apex below ; this space is bounded above by the mucous membrane of the mouth, externally by the mylohyoid muscle, and internally by the hyo-glossus, stylo-glossus, and genio-glossus muscles. In it are contained the sublingual gland, the deep process of the submaxillary and the duct of that gland with the lingual branch of the fifth and the ninth nerves; in the anterior part and superiorly, immediately beneath the mucous membrane, is situate the sublingual gland ; at the posterior and rather inferiorly the deep process of the submaxillary ; while the nerves and the duct are placed at the posterior or external part of the lingual branch of the fifth above, imme- diately beneath the mucous membrane; the ninth below, along, and above the cornu of the os hyoides, and the duct between the nerves; but as the three parts pass forward, the duct and lingual branch cross each other, the nerve descending, the duct ascending be- tween the nerve and the hyo-glossus, and in consequence of this circumstance, at the ante- rior part of the space, the duct is superior, the lingual branch is intermediate, and the ninth nerve is below. At first the lingual branch is above the deep process of the submaxillary gland, then it is situate internal and superior to it, external and inferior to the duct; as it pro- ceeds, it is beneath the sublingual gland, and, lastly, it ascends internal to that gland, between it and the genio-glossjj^4e£e*der to reach the tongue. j\s\^*~ ^Sfir At the posterior part of the space, the nerve is immediately beneath the mucous membrane; as it proceeds it descends from, but toward the anterior part again ascends, and is in con- tact with the membrane as it becomes attached to the tongue. Having reached the anterior margin of the hyo-glossus the nerve breaks up into three branches, posterior, middle, and anterior. Of these the posterior is the shortest, and ascends almost directly ; the middle runs upward and forward, and the anterior, which is much longer than, and at the same time inferior to the others, almost directly forward, along the under surface of the tongue, between the genio- glossus and the stylo-glossus ; the former muscle internal, the latter external to it. In its course beneath the tongue it is accompanied by the ranine artery, which joins it at the anterior margin of the hyo-glossus, and is situate inferior to it, immediately above the mucous membrane. The lingual nerve does not give off many branches in the first part of its course : soon after its origin it receives the branch of com- munication, by which the inferior dental nerve is connected to it. About the same point or presently after it is also joined by the chorda tympani. The uncertainty which has prevailed with regard to the source of this nerve renders 296 FIFTH PAIR OF NERVES. a more particular account of it necessary than would otherwise be required. The chorda tym- pani — a delicate filament — is given offfrom the portio dura shortly before that nerve escapes from the aqueduct of Fallopius, behind and be- low the tympanum : it passes upward and for- ward toward the tympanum, contained in a spe- cial canal of the bone, and having reached the back of the chamber it emerges from its posterior wall through a small aperture beneath the base of the pyramid; it then attaches itself to the outer wall of the tympanum and crosses it toward the anterior, having first received* a delicate filament from the sympathetic, and running forward, upward, and outward. During its course from the posterior to the anterior wall it is situate at first beneath the short cms of the incus, then between the long crus of the incus and the superior part of the handle of the malleus, to which it is connected by the lining membrane of the tympanum. Having ascended above the internal muscle of the malleus it changes its direction and runs down- ward, forward, and inward along the superior anterior part of the circumference of the mem- brana tympani, until it has reached the anterior wall of the chamber, from which it goes out through the Glaserian fissure, along the tendon of the anterior muscle of the malleus. It is throughout excluded from the interior of the tympanum by the lining membrane, which is connected to it upon that side ; it is therefore incorrect to say that it crosses the chamber. After its escape from the tympanum the nerve continues to descend forward and inward in front of the levator palati muscle, and after a course from three-fourths of an inch to an inch long it is attached at a very acute angle to the back of the lingual branch, becomes inclosed in the same sheath with the nerve, and con- tinues connected with it altogether until the nerve has reached the posterior extremity of the submaxillary gland : at that point the chorda tympani divides into two parts, one of which is despatched to the submaxillary gan- glion, and the other continued along with the lingual branch. By somef it is stated that it separates from the nerve at the ganglion, and is altogether ununited to it; this, however, is incorrect. During its descent in company with the lingual branch there may be observed, upon particular examination of the conjoined trunk, a communication and identification be- tween the nervous matter of the two nerves. Originally the chorda tympani was regarded as either a recurrent filament of the lingual branch of the fifth or a branch of the portio dura : afterwards the opinion was adopted that it was not a branch of the portio dura, but the cranial superficial petrous branch of the Vidian nerve, which, instead of uniting and being iden- tified with the portio dura, descended through the aqueduct merely in apposition with it or within the same sheath, separated from it again before the nerve escaped from the aqueduct, and constituted the chorda tympani. This view * Bock, Meckel junior, Cloquet. t Cloquet. of the nature of the chord, suggested first, as it would appear, by J. Hunter, has been advo- cated also by Cloquet and Hirzel, and is at present entertained by many in this country at least; it has been objected to by Arnold, and another has been advanced by him from obser- vations made upon the calf and the human subject. Hunter's account of the connection of the nerves is as follows : " This nerve com- posed of portio dura and the branch of the fifth pair sends off, in the adult, the chorda tympani before its exit from the skull, and in the foetus, immediately after. The termination of the branch called chorda tympani I shall not de- scribe, yet I am almost certain it is not a branch of the seventh pair of nerves, but the last-described branch from the fifth pair," i. e. the Vidian, " for I think I have been able to separate this branch from the portio dura, and have found it lead to the chorda tympani ; per- haps is continued into it ; but this is a point very difficult to determine, as the portio dura is a compact nerve, and not so fasciculated as some others are."* According to Arnold, nei- ther of the previous opinions is correct; but the petrous nerve anastomoses with filaments of the facial nerve, principally the external, with which it forms a gangliform swelling at the place at which the nerve receives it ; and the branch which forms the corda tympani arises from the gangliform swelling of the facial nerve, and holds in an intimate manner to the petrous nerve ; however it is not to be consi- dered a continuation of the latter : it is united, during its course, to the facial nerve by several filaments, and consequently the chorda tympani ought to be regarded neither as a branch of the facial nerve nor as a continuation of the petrous nerve, but as one composed of both.f Cru- veilhier J maintains that the chorda tympani is not a prolongation of the Vidian nerve, but he assigns no reason for his opinion. The ques- tion at issue probably cannot be decided from the human subject: the impediment opposed to its satisfactory determination by the density of the facial nerve, as admitted by Hunter, and by the manner in which the facial and the Vidian nerves are in it blended together at their junction, will hardly permit the point being accurately ascertained ; but the same diffi- culty does not exist in other animals, and if the disposition of the Vidian nerve at its junction with the facial be examined, in the horse e.g., no doubt will remain that, 1. the Vidian nerve certainly does not run simply in apposition with the facial nerve, and, 2. the chorda tympani is certainly not a mere conti- nuation of the Vidian nerve. In the horse the facial nerve is much less dense, and more easily analyzed than in man, and at the point of junc- tion with the Vidian its filaments are so free and so loosely connected, that little more is re- quired than to open the packet without violence in order to display satisfactorily the disposition of the Vidian at its junction with the facial : the * Animal (Economy, p. 267. t Journ. Compl. t. xxiv. p. 339, 341. i Anatomie Descriptive. FIFTH PAIR OF NERVES. 297 Vidian passes into the interior of the packet, crossing its fasciculi nearly at right angles, but rather in a reflex direction, and then spreads out and breaks up into a number of very delicate fila- ments with which cineritious matter is inter- mixed, and thus a ganglionic structure is pro- duced, which is in some instances more mani- fest than in others, and is at the same time connected with fasciculi of the facial nerve. The filaments into which the Vidian separates can be followed in both directions, some re- trograde, and some along with the facial : the former appear to pass partly to the auditory nerve, as stated by Arnold, and partly to the facial between the point at which the Vidian joins it and the brain : they can be rent from the one into the other, and indeed look more like filaments from the facial to the Vidian than from the latter to the former. The latter fila- ments of the Vidian are dispersed among the fasciculi of the facial, with which they become united, and can be followed by means of a careful dissection for some distance : their number the writer is not prepared to state : the fasciculus of the facial from which the chorda tympani more particularly arises, appears deci- dedly to receive one or it may be more. Fur- ther, the chorda tympani does not arise by a single root, but is formed by two or tliree de- rived from different parts of the facial. The opinion that the chorda tympani is a continu- ation of the Vidian nerve appears, therefore, to the writer altogether unfounded, and while he admits that the conclusion of Arnold may proba- bly be well-founded, with regard to its compound nature, he yet must dissent from the opinion that the branch which forms it arises immediately from the gangliform swelling of the facial : the fasciculus, from which its principal root pro- ceeds, existing distinctly upon both sides of, and consequently not arising from the swelling, however it may receive an accession from, or be affected by its connection with this part. The author cannot refrain from regarding the chord as a branch of the facial nerve in the same sense with any other branch arising within the limits of the influence of the Vidian nerve. Magendie maintains that the chord is a continuation of the Vidian, because the section of the fifth nerve itself deprives the ear of all sensibility, but whatever part the chord may play in the sensi- bility of the ear, and it is doubtful that it plays any, the result of the experiment will be easily explained by the doctrine of Eschricht, that the facial nerve owes its sensibility to the fifth nerve, the division of which must in such case influence through the Vidian nerve any branch of the facial arising within the range of its in- fluence. After the junction of the chorda tympani with the lingual branch, the latter gives at times a small branch to the internal pterygoid mus- cle : during its descent along the ramus of the jaw, it also gives filaments to the arches of the palate, to the mucous membrane of the cheek, and to the gum of the lower jaw. While the nerve is situate between the mucous membrane of the mouth and the submaxillary gland, it is connected by means of two, three, or four fila- ments with the submaxillary ganglion. This ganglion is a small reddish body resembling the spheno-palatine ganglion in size, colour, and consistence, situate above the posterior extre- mity of the submaxillary gland, and connected superiorly with the lingual branch by the fila- ments mentioned ; inferiorly there arises from it a considerable number of very delicate nerves, which descend through the divisions of the gland, anastomose with each other, and are distributed for the most part to the substance of the gland ; one of them descends upon the hyoglossus, anastomoses with a filament from the ninth, and enters into the genioglossus muscle, and another long one accompanies the duct of the gland. A filament of communi- cation also from the superior cervical ganglion of the sympathetic reaches the submaxillary ganglion by following the course of the facial artery, and is represented by Arnold. The filaments by which the ganglion is con- nected to the lingual branch, are, as has been stated, two, three, or four ; they are not attached to the nerve all together, but one or two some lines before the others, and they are remarkable for the circumstance, that the posterior descend forward, while the anterior descend backward ; on attentive examination it is found that the posterior are derived one from the chorda tym- pani, and the other from the lingual branch itself ; it also appears that the filament derived from the former source is but a part of the cord, the remainder being continued on with the trunk of the lingual, and again that the anterior filament or filaments, which descend backward to the ganglion, are continuations of the poste- rior, which, after having been connected to the ganglion, ascend forward from it again to the trunk of the nerve. The course of those fila- ments of connection is well described and re- presented by the elder Meckel, and a very accu- rate delineation of them is given by Treviranus and Arnold. To this connection probably it is, that we are to attribute the influence which impressions on the organs of taste, or even sounds exert upon the salivary apparatus ; let us, when hungry, only hear a sound associated in our minds, in any way, with the gratification of our appetite, and at once that apparatus is roused into activity. Next, while lying between the mylohyoid and the hyoglossus muscles, the lingual nerve sends off from its inferior side some branches, which descend upon the hyoglossus, and anastomose with filaments ascending from the ninth nerve. At the same time, from its superior side, it gives filaments ; some of which, the posterior, are distributed to the mucous membrane and to the gum of the lower jaw ; others, the ante- rior, to the sublingual gland, and by some of their ramifications to the membrane and the gum. Lastly, the nerve divides at the anterior margin of the hyoglossus into its lingual branches ; these are, at first, three, poste- rior, middle, and anterior ; they pass up- ward and forward, and divide, each into two or three branches, which altogether di- verge from the nerve, and are ranged in suc- cession from behind forward, along the line 298 FIFTH PAIR OF NERVES. of separation between the stylo-glossus and the genio-glossus ; they traverse the substance of the tongue toward its superior surface and mar- gin, and run along its inferior surface, above the mucous membrane, toward its extremity ; as they proceed they subdivide, and thus re- sults a great number of filaments, the course of which through the tongue is remarkable ; they appear not to terminate, any of them, in the substance of it, but they traverse it as long, slender, single filaments, unconnected with its structure until they approach its superior sur- face, when they break up into pencils (to adopt the phrase used) of still more delicate filaments, which may be followed into the mu- cous membrane ; the posterior filaments of the posterior branch insinuate themselves internal to the hyoglossus, and reach as far back as the foramen coecum ; the filaments of the anterior are distributed to the extremity of the tongue, and are continued between the under surface of it and the mucous membrane very near to the tip, the substance of which they then tra- verse in order to reach its superior aspect and margin : they thus supply the mucous mem- brane of the organ upon its superior and lateral parts, from the foramen ccecum to its point. Ganglion of the fijtk nerve (Ganglion semilunare Gasseri). See Jig. 140, 9. — The ganglion of the fifth nerve is a body of crescentic form, a cineritious colour, and firm consistence. It presents two surfaces, two margins, and two extremities : its surfaces are both slightly pro- minent, and are directed one upward, outward, and forward, the other downward, inward, and backward ; they are also, the former con- cave and the latter convex longitudinally, the ganglion being somewhat curved upon itself in the same direction : they are both for the most part adherent to the lamina? of dura mater, which form the chamber in which the gan- glion is contained ; but it is not uncommon to find the arachnoid membrane prolonged beneath it, so that its inferior surface in such instances is free ; the superior corresponds to the cranial cavity in its middle fossa, being excluded from it only by the dura mater; the inferior rests, with the intervention of dura mater also, upon the petrous portion of the temporal bone, the great ala of the sphenoid, and against the outer side of the cavernous sinus. The margins of the ganglion are di- rected one forward and downward, the other backward and upward ; the anterior is convex, and to it are attached the three great trunks, which compose the ganglionic portion of the nerve in its third stage ; the posterior is con- cave and presents through its entire length a deep groove, into which the fasciculi of the ganglionic packet of the nerve are received. The extremities are obtuse, and project beyond the packet at either side ; they are situate re- latively, one superior, internal, and anterior to the other. When the ganglion is in situ, the chord of the arch which it forms is six or seven lines long ; Niemeyer has sometimes found it amount to from nine to ten:* its width * De origine pans quinti nervorum cerebri mono- graphia, Halae, 1812. is about two lines, and its thickness, according to the part, from half a line to a line. Its colour and appearance vary much according to the subject : the former is always of a cine- ritious tint of different degrees of intensity ; when the subject is wasted, flabby, or anasar- cous, it is pale or grey, while, if the subject have been robust and corpulent, it is of a deep brown colour : in the former case also a plexi- form arrangement is more perceptible, whereas in the latter the ganglion seems composed of two concentric arcs, an anterior of lighter colour and manifestly plexiform character, and a posterior of very deep colour and apparently homogeneous indeterminate texture, devoid al- together of the plexiform appearance. A particular inquiry into the structure and probable function of the ganglion of the fifth nerve would involve that of the cerebro-spinal ganglia in general, and will be better post- poned to another occasion : it will suffice for the present to state that according to both Monro and Scarpa, they are composed in part of nervous chords, and in part by a soft grey or brown substance, which fills the intervals between the nervous filaments, and which according to the former resembles the cortical matter of the brain, while in the opinion of the latter it is a cellular texture filled by a matter, which varies in character according to the subject; thus he states that he has found it fatty in fat and watery in anasar- cous subjects. 2. That nervous filaments can be traced through them without interruption from the nerves situate above to those situate below the ganglion, which opinion is objected to by Niemeyer, who compares the connection of the former with the ganglion to that of the foetal and maternal portions of the placenta ; but inspection suffices to satisfy one that this idea of Niemeyer is incorrect; for whether additional filaments be furnished or not by the ganglion, the continuity of filaments above and below it is evident even in the human subject, and is still more manifest in other animals : in the horse it is easily seen, par- ticularly after a section of the ganglion. The question whether the ganglion receives filaments from the sympathetic system has been a subject of dispute among anatomists. The elder Meckel* denies the existence of any filaments of connection between the sympa- thetic and the fifth nerve, while within the fibrous chamber or while situate by the cavern- ous sinus ; and others also, among whom are Eustachius, Haller, Albinus, and Morgagni, are of the same opinion ; but later investiga- tions have put it beyond doubt that such a communication does exist. Bockf has de- scribed filaments of the sympathetic united to the trunk of the fifth, before the formation of the Gasserian ganglion, and which join chiefly the fasciculi of the trunk, from which the ophthalmic nerve originates. And Arnold * Scriptores Neurologici Minores, torn. i. t Beschreibung des funften Nervenpaares und seiner Verbindung mit andern Nerven, vorzuglich mlt dem Gangliensystem, 1817. FIFTH PAIR OF NERVES. 299 states M that several very delicate filaments go from the carotid plexus to the semilunar gan- glion, particularly to the first and third branches of the nerve, and upon those points the gan- glionic matter is accumulated in greater abun- dance."* Besides this connection between the sympathetic and the ganglion, others exist between it and the branches of the ganglion. The ganglion appears to constitute an essen- tial part of the fifth nerve throughout verte- brate animals, and to be uniformly present. It also presents in all the common character of being composed both of white and cineri- tious matter, though the comparative amount of the two constituents vanes according to the class, the order, or even the individual. The presence of the two structures the author would regard as essential to the constitution of cerebro-spinal ganglia, and he would ex- clude from such those enlargements presented by nerves in certain situations, but from which cineritious matter appears to be absent. In Mammalia, Birds, and Reptiles, the fifth nerve is provided with a single ganglion, but in Fish and in both orders of that class it possesses for the mosi part two ganglia and two gan- glionic fasciculi ; this however is not uniformly so, for in some, e. g. the lophius piscatorius, the ganglion is single. Vital Properties of the Fifth Pair of Nerves. — The discussion of the vital properties of the fifth nerve the writer pro- poses may be fitly arranged under the following heads: 1. its sensibility; 2. its influence upon the faculties of sensation and volition, as also upon the ordinary sensibility of the parts to which it is distributed; 3. its relation to the special senses and connection with the function of nutrition. 1. Sensibility. — Numerous experiments per- formed and repeated by different physiologists have established the fact, that the filth nerve enjoys exquisite sensibility. Bell appears to have been the first who directed attention particularly to this point: in his paper, pub- lished in the Philosophical Transactions for the year 1821, it is stated that, touching the su- perior maxillary branch of the fifth nerve, when exposed in an ass, " gave acute pain." In the first of Mayo's experiments upon the fifth nerve, published in his Commentaries in 1822, it was also found that " on pinching the opposite extremities" (those connected with the brain) " of the infraorbital and inferior maxillary nerves in an ass, the animal struggled violently as at the moment of dividing the nerves: these latter results uniformly attend the division of the nerves above-mentioned, and of that branch of the fifth which joins the portio dura."! Similar results were obtained by the writer last quoted from experiments of the same description upon the dog and the rabbit, and upon the pigeon, in regard to the first division of the fifth. He also found " that on pinching the gustatory nerves in living rabbits pain was evinced." Magendie * Journ. Compl. torn. xxiv. t Commentaries, No. 1, p. 110. carried the inquiry farther, and in the fourth volume* of the Journal of Physiology, has related an experiment in which he exposed the fifth nerve within the cranium in the rabbit and dog, and found that the slightest touch produced signs of acute sensibility. From the preceding facts we infer that the ganglionic portion of the nerve at least is exquisitely sensitive, and that it is endowed with sen- sibility through its entire extent : further, the experiment of Magendie indicates that the sen- sibility of the nerve is proper and independent of the influence of other nerves, he having ex- perimented upon it at a point prior to its junction with any other. With regard to the non-ganglionic portion of the nerve, our data are at present altogether analogical : it is so situated that satisfactory experiments upon it separately are hardly to be accomplished, so that we are left to infer of it as probable what has been ascertained of other non-ganglionic nervous cords, viz. the anterior roots of the spinal nerves. The question in regard to the functions of the different portions of the spinal nerves has been inquired into by Magendie, by whom the endowments of both sets of roots have been tested in various modes, and who has inferred that the anterior roots are not devoid of sen- sibility, and if they be sensitive it is probable that the lesser packet of the fifth is sensitive also.f 2. Influence of the fifth nerve upon sensation and volition. — It is hardly necessary to remark that this point has been the subject of much dispute, as well with regard to the fact itself as to the relative claims of the several inquirers to whom we are indebted for the investigation of the matter: however, physiologists now seem to be generally agreed that the nerve is one of compound function, being subservient to both the faculties of sensation and volition, and that the faculty of sensation is dependent upon its ganglionic, that of voluntary motion upon its non-ganglionic portion, and that it thus resembles the spinal nerves. That the nerve is one of compound function, and sub- servient to the two faculties, was announced by Bell in the paper already alluded to. He there distinguishes the nerves into two classes ; one original and symmetrical, the other super- added and irregular. To the former class he refers the spinal nerves, the suboccipital, and the fifth nerve, and assigns to them the fol- lowing characters, namely, they hive all double origins ; they have all ganglia on one of their roots ; they go out laterally to certain divisions of the body; they do not interfere to unite the divisions of the frame ; thei/ are all mus- cular nerves, ordering the voluntary motions of the frame ; they are all exquisitely sensible, and the source of the common sensibility of the surfaces of the body : to ii he refers the nerves of the spine, the suboccipital, and the fifth nerve. I It has been already stated that * P. 314. t Journal tie Physiologie, t. ii. p. 368. X Philosophical Transactions, 1821, p. 404. 300 FIFTH PAIR OF NERVES. he had ascertained by experiment that the fifth nerve was exquisitely sensitive ; that it is the source of the sensibility of the parts to which it is distributed, he has also determined, for in allusion to the fifth he says, " if the nerve of this original class be divided, the skin and common substance is deprived of sensibility;"* and " by an experiment made on the 16th of March, it was found that, on cutting the infra-orbitary branch of the fifth on the left side, the sensibility of that side was completely destroyed/' f The experiments of Bell were repeated by Magendie, and a similar result, so far as regards the sentient properties of the fifth, obtained, as mentioned in the Journal de Physiologie, Octobre 1821. A similar result has been obtained also by Mayo in his experiments upon the fifth nerve, as detailed in his Commentaries for August 1822, more than a year after the publication of Bell's paper. In his first experiment the infra-orbital and inferior maxillary branches were divided on either side in an ass, where they emerge from their canals, and the sensibility of the lips seemed to be destroyed : and, in a second experiment, the frontal nerve was divided on one side of the forehead of an ass, when the neighbouring surface appeared to lose its sen- sibility : the same effect was produced by the division of that branch of the fifth which joins the portio dura, inasmuch as the cheek loses sensation upon its division. From these ex- periments Mayo concluded that the facial branches of the fifth are nerves of sensation. The experiments upon the influence of the nerve on sensation have been carried still further by Magendie ; he divided the nerves within the cranium, where they lie against the cavernous sinus, and also between the pons Varolii and the petrous portion of the temporal bone, and in both instances he obtained the same result with regard to the sensibility of the parts to which the nerves are distributed, viz. total loss of sensibility on one or both sides of the face, according as one or both nerves were divided ; this extended not only to the integuments as in the former trials, but also to the lining membrane of the nostrils, to the conjunctiva, to the tongue and the interior of the mouth. The effect upon the nostril was so remarkable that the most active effluvia, even those of ammonia and acetic acid, pro- duced no impression upon it: in like manner neither piercing instruments nor ammonia ex- cited any sensation when applied to the con- junctiva, and the tongue was insensible to the action of sapid bodies at its anterior part. From such accumulated evidence but one conclusion can be drawn, viz. that the fifth is the nerve of general and tactile sensation to the face and its cavities, or to the parts upon which it is distributed. With regard to the influence of the fifth nerve upon volition, it has been already stated that Bell had announced it, as one of his regular or symmetrical nerves, to be " a muscular * Philosophical Transactions, 1821, p. 405. f Ibid. p. 417. nerve ordering the voluntary motions." This conclusion with regard to the fifth nerve he adopted in consequence of the following ex- periment, and of the result, which, as he conceived, he obtained from it. " An ass being tied and thrown, the superior maxillary branch of the fifth nerve was exposed. Touching this nerve gave acute pain. It was divided, but no change took place in the motion of the nostril ; the cartilages continued to expand regularly in time with the other parts which combine in the act of respiration ; but the side of the lip was observed to hang low, and it was dragged to the other side. The same branch of the fifth was divided on the opposite side, and the animal let loose. He could no longer pick up his corn ; the power of elevating and projecting the lip, as in gathering food, was lost. To open the lips the animal pressed the mouth against the ground, and at length licked the oats from the ground with his tongue. The loss of motion of the lips in eating was so obvious, that it was thought a useless cruelty to cut the other branches of the fifth." The inference here indicated is obvious, viz. that the motion of the lips in eating depends upon the superior maxillary branches of the fifth pair, so far at least as the distribution of those branches extends ; and what he conceived he had thus established with regard to one branch he inferred analogically of the rest. The opinion that the fifth is a muscular nerve as well as one of sensibility Bell also maintains in later writings, and supports by additional experiments : thus, in his Erposition of the Natural System of the Nerves, published in 1824, he says, " to confirm this opinion by experiment, the nerve of the fifth pair was exposed at its root, in an ass, the moment the animal was killed ; and on irritating the nerve the muscles of the jaw acted, and the jaw was closed with a snap. On dividing the root of the nerve in a living animal, the jaw fell relaxed." That the fifth is to a certain extent a nerve of voluntary motion is univer- sally admitted, but then a question arises of equal interest and delicacy; of interest for its own nature, and of delicacy because of the personal claims and feelings involved in it. The question is, — it being admitted that the nerve is one of double function, — is such function enjoyed equally by all its branches and by both its portions ; and if otherwise, upon which do they severally depend ? From the extracts quoted it is evident that no dis- tinction in function between the different branches of the nerve was contemplated by Bell at the time the first was written, in 1821, and that he regarded them as being all alike nerves of compound function, — nerves both of voluntary motion and sensation; and, such being the case, either that he had not recognised a difference between the properties of the gan- glionic and the non-ganglionic portions of the nerve, or that he was then not aware of the peculiar distribution of the latter ; nor is any express information afforded us upon the subject in his earlier writings, or antecedent to 1823. The conclusion to which he had arrived with FIFTH PAIR OF NERVES. 301 regard to the nerve generally and its superior maxillary branch in particular, in the year 1821, has been stated ; in his communication to the Royal Society in 1823, he adds, " all the nerves, without a single exception, which bestow sensibility from the top of the head to the toe have ganglia on their roots ; and those which have no ganglia are not nerves of sensation, but are for the purpose of or- dering the muscular frame:" from this, when applied to the fifth nerve, it might be inferred that sensation depended upon its ganglionic, and muscular action upon its non-ganglionic portion. But between the years 1821 and 1823 additions had been made by others to the knowledge of the functions of the fifth nerve which require notice. It is to be borne in mind that Bell inferred from his first ex- periment, published in 1821, that the superior maxillary nerve is one both of sensation and voluntary motion to the lips (see the preceding page) : to this conclusion Magendie was the first to object, for in the Journal of Physiology for October of the same year (1821), he says, " we have repeated these experiments along with Messrs. Shaw and Dupuy, and the result which we have obtained agrees perfectly with that which we have just related, with the ex- ception always of the influence of the section of the infra-orbital upon mastication, an in- fluence which I have never been able to perceive." In August 1822 Mayo published, in his Com- mentaries, his " experiments to determine the influence of the portio dura of the seventh, and of the facial branches of the fifth pair of nerves." Those relating to the latter point, which have been already alluded to, are as follow. 1. The infra-orbital and inferior max- illary branches of the fifth were divided on either side, where they emerge from their re- spective canals; the lips did not lose their tone or customary apposition to each other and to the teeth ; but their sensibility seemed destroyed : when oats were offered it, the animal pressed its lips against the vessel which contained the food, and finally raised the latter with its tongue and teeth. On pinching with a forceps the extremities nearest the lips of the divided nerves, no movement whatever of the lips ensued : on pinching the opposite extremities of the nerves, the animal struggled violently, as at the moment of dividing the nerves. Some days afterwards, though the animal did not raise its food with its lips, the latter seemed to be moved during mastica- tion by their own muscles." 2. " Some days after, the frontal nerve was divided on one side of the forehead of the same ass, when the neighbouring surface appeared to have lost sensation, but its muscles were not paralysed." 4, 5, and 6. The branch of the fifth, that joins the portio dura, was divided on either side : in the fourth experi- ment, the under lip at first appeared to fall away from the teeth; at times the lips were just closed: in the fifth and sixth, the under lip did not hang down, and no difference was observed between the action of the muscles of either side ; but, he observes in a later publi- cation, " the cheek loses sensation upon its division." The results of these experiments, while they confirm fully the inference drawn by Bell with regard to the influence of the nerve over sensation, are altogether at variance with that of his experiment relating to the con- trol of the superior maxillary nerve over mus- cular motion, and are equally incompatible with the doctrine that the branches of the nerve., which were the subjects of experiment, have any direct connexion with muscular contrac- tion ; for while, on the one hand, the division of the nerves was followed by total loss of sensibility in the lips, on the other, the latter did not fall away either from each other or from the teeth, nor did irritation of the portions of the nerves connected with the lips excite any movement whatever of those parts, but they seemed afterwards to be moved during mastication by their own muscles. Mayo in- ferred accordingly from his experiments, " that the frontal, infra-orbital, and inferior maxillary are nerves of sensation only, to which office that branch of the fifth which joins the portio dura probably contributes." A circumstance in the first experiment doubtless seems at variance with the conclusion which Mayo has drawn, and demands consideration here, be- cause, unless unexplained, the fact is inconsis- tent with the inference. It has been stated that both in Bell's and Mayo's experiment, the animal ceased to take up its food with its lips after the division of the facial branches of the fifth, and from that circumstance chiefly the former appears to have inferred that the motions of the lips in eating depended on these nerves ; but the inference is objected to by Mayo as " a theoretical account of the fact that the animal did not elevate and project its lip ; this fact," he says, " was noticed in my own expe- riments, but appeared to me from the first equally consistent with the hypothesis, that the lip had merely lost its sensibility, as with Mr. Bell's explanation," that it had lost its muscu- lar power. The fact may be obviously ex- plained by either of the two suppositions, and it is very remarkable that it should occur equally in one case as in the other. In the one, the muscles of the lips having been de- prived of their power of voluntary contraction, the lips themselves cannot, of course, be made use of to take hold of an object ; and in the other, the animal not being made aware of the contact of the food in consequence of the loss of sensation, volition is not exerted, nor are the muscles called into action in order to take hold of it. To the latter cause it is attributed by Mayo, after the division of the branches of the fifth, and he confirms this view of its pro- duction by reference to the effect of anaesthesia in the human subject : " in that disease the sensation of the extremities is wholly lost, while their muscular power remains. Now it is remarkable that in persons thus affected the muscles of the insensible part can only be exerted efficiently when another sense is em- ployed to guide them, and to supply the place of that which has been lost : a person afflicted with anaesthesia is described in a case quoted 302 FIFTH PAIR OF NERVES. by Dr. Yelloly, as liable on turning her eyes aside to drop glasses, plates, &c. which she held in safety so long as she looked at them ;" but that the absence of motion in the lips on the division of the fifth is due to the loss of sensation merely, and not of voluntary power, is positively proved by the effect of the division of the portio dura on the two sides, an experi- ment performed for the first time by Mayo : in it the voluntary motion of the lips is altogether lost, while sensation continues unaffected,* and hence the division of the fifth cannot deprive them of voluntary power, but only of sensation. The explanation of Mayo has been admitted and adopted by Bell himself in his " Exposi- tion," 1824, in which he has added to the detail of his experiment, as already related, the following note : " what I attributed to the effect of the loss of motion by the division of the fifth, was in fact produced by loss of sen- sation;" and he corroborates this by the case of a gentleman in whom loss of sensation in the lip had been produced by extraction of a tooth. " On putting a tumbler of water to his lips, he said, ' Why, you have given me a broken glass :' he thought that he put half a glass to his lips, because the lip had been de- prived of sensation in one half of its extent ; lie retained the power of moving the lip, but not of feeling with the lip." The last particu- lar noted is of great value, as demonstrating satisfactorily the separation of the two faculties, and, taken in connexion with anatomical con- siderations, renders it necessary to refer them to separate sources. It is manifest, then, that the circumstance of the animal not taking up the food by means of the lips, after the divi- sion of the fifth nerve, is not proof that it had lost the voluntary muscular power of them, but only that it did exert it, not having been, as it were, apprised of the necessity of doing so. It is also stated by Bell, that on the division of the nerve upon one side, " the side of the lip was observed to hang low, and it was dragged to the other side." This result also is objected to by Mayo, first, as contrary to his observation, for in his first experiment, after the division of the infra-orbital and inferior maxillary nerves, " the lips did not lose their tone or customary apposition to each other and to the teeth;" and secondly, as being the effect of an extensive division of the muscular fibres, a cause quite adequate certainly to explain the fall of the lip, independent of the influence of the nerves. The difficulty, there- fore, which these circumstances appear at first to present is removed, and we are left to deter- * It will be satisfactory to those interested in this question to know, that the result of Mayo's experiment has received full confirmation from those of others; and first from Shaw, who has bestowed so much labour to establish the respiratory connexion of the portio dura. In the Medical and Physical Journal for December, 1822, he writes, " immediately on cutting the nerve (the portio dura) on both sides, the lips became so paralyzed that the animal could no longer use them in raising its food." The same result has been obtained by Mr. Broughton in experiments upon the horse, as detailed in the same Journal, June, 1823. mine the question by other means, and they are abundantly furnished from other sources. In the first place, the division of the nerves completely destroys the sensation of the parts to which they are distributed, without pro- ducing any effect upon the tone or contractile power of those parts, nor does irritation of the divided nerves excite muscular contractions. Secondly, were these nerves the source of the voluntary powers of the parts they supply, the division of every other nerve must fail to affect that power while the former remain entire; but Mayo, in several instances, divided the portio dura alone on both sides, and the result was, that " the lips immediately fell away from the teeth, and hung flaccid," and could not be used by the animal to take hold of food, and consequently had lost ail volun- tary power ; while, " when the extremity, nearest the lips, of either divided nerve was pinched, the muscles of the lips and nostrils on that side were convulsed." Bell doubtless asserts that after the division of the portio dura nerve on one side, the animal " ate without the slightest impediment;" to this Mayo objects that " the experiment is inconclusive, because the nerve was not divided on both sides;" but in truth the experiment is quite conclusive, for though the animal can eat, and without impediment, his eating is far from perfect, and the imperfection is not the less obvious because confined to one side. When an animal which has had the portio dura divided upon one side only takes food, the lips remain motionless upon that side; and when it masticates, the lips continue in the same state, while on the otheT side they ac- tively co-operate, the food and saliva escaping on the side at which the nerve has been cut, and on the other being confined within the mouth. Now, if any action of the lips be voluntary, it is assuredly that by which they co-operate in the prehension and mastication of food ; and since no action of their muscles can be excited by irritation of the branches of the fifth nerve, while such action can be ex- cited by that of the portio dura, and all volun- tary action is destroyed by the division of that nerve, but one inference remains, that ot Mayo already adverted to, viz. — that those branches of the fifth in question possess no influence upon the voluntary faculty of the muscles ; that they are exclusively sentient ; and that the contractile power of the muscles of the face, whether voluntary or involuntary, is to be attri- buted to another source. After what has been stated, we must admit that Mayo has been the first expressly to an- nounce that the function of these nerves is restricted to sensation. Beyond that, however, he has not gone, in reference to the question of sensation, in the publication alluded to, though it must be admitted that little remained to be added in order to complete the conclu- sion, that the ganglionic portion of the nerve is exclusively sentient. At the same time he inferred, " from the preceding anatomical details," — viz. their exclusive distribution to muscles, — " that other branches of the third FIFTH PAIR OF NERVES. 303 division of the fifth are voluntary nerves to the pterygoid, the masseter, the temporal, and buccinator muscles." Here again he has not reached the conclusion, though he has fallen but little short of it, and though, as in the former instance with regard to sensation, he has been the first to announce a restriction of the motor properties of the nerve to particular branches. The opinion expressed by Bell, in June 1823, has been already quoted, and from it we are bound to admit, that then at least he recognised the distinction at present acknow- ledged with reference to the appropriate function of the ganglionic and non-ganglionic portions. But in Mayo's Commentaries for July 1823, the conclusion is for the first time expressly stated thus : — " In the last paper of the preceding number, I mentioned that the division of the supra-orbital, infra-orbital, and inferior max- illary nerves, at the points where they emerge from their canals upon the face, produces loss of sensation, and of that alone, in the corres- ponding parts or the face. I have since, after the division of the fourth branch which emerges on the face, — namely, that which joins the portio dura, — ascertained that this branch like- wise is a nerve of sensation, inasmuch as the cheek loses sensation upon its division. I mentioned in addition that I concluded that other branches of the fifth nerve, from their distribution, are voluntary nerves. Now it is well known that the fifth nerve at its origin consists of two portions ; a larger part, which alone enters the Gasserian ganglion, and ano- ther smaller, which does not enter, but passes below the ganglion to join itself with the third division of the fifth. Towards the close of last summer I endeavoured to trace the final distribution of this small portion in the ass, and succeeded in making out that it furnishes those branches, which are. distributed exclu- sively to muscles : I have since ascertained that in the human body precisely the same distribution exists. But the iemaining branches of the fifth are proved to be nerves of sensation ; thus it appears that the fifth nerve consists of two portions, one of which has no ganglion, and is a nerve of voluntary motion (and pro- bably of muscular sensation) ; and another, which passes through a ganglion, and furnishes branches, which are exclusively nerves of the special senses." We return now to the question of the pro- perties of the non-ganglionic portion of the fifth nerve. It has been stated that Mayo was the first to announce the restriction of the voluntary influence of the fifth to certain branches, and that he was led to this conclu- sion from the observation of the fact that certain branches of the nerve ate distributed exclusively to muscles. These muscles he has stated, in the first part of his Commentaries, to be the pterygoid, the masseter, the temporal, and buccinator; to which he has added, in his second part, the circumflexus palati ; by dis- section he ascertained that as well in man as in the ass, the lesser portion of the nerve " fur- nishes those branches which are distributed ex- clusively to muscles;" and having already determined that the ganglionic portions of the nerve are destined exclusively to sensation, he came to the conclusion that the non-ganglionic portion is a nerve of voluntary motion. His first conclusion upon this point he himself states to have " involved a trifling error : the pterygoid, masseter, and temporal muscles are indeed exclusively supplied by the fifth, and therefore, without doubt, the branches so dis- tributed are voluntary nerves, but the bucci- nator receives branches from the portio dura as well, and I have found subsequently, that pinching the branch of the fifth that perforates the muscle, produces no action in it : and in accordance with this view he writes in his Physiology,* " I was led to observe that there were muscles which received no branches from any nerve but the fifth ; these muscles are the masseter, the temporal, the two pterygoids, and the circumflexus palati. After some care- ful dissection, I made out that the smaller fasciculus of the fifth is entirely consumed upon the supply of the muscles 1 have named." The determination of the constitution and function of the buccal branch of the inferior maxillary nerve has become a matter of greater importance since the publication of Bell's work on the Nervous System in 1830. In it he says, " I am particular in re-stating this, because from time to time it has been reported that I had abandoned my original opinions, whereas every thing has tended to confirm them." Now, it will be remembered that Bell's original opinion is, that the muscles of the face are endowed with two powers, a volun- tary one, dependent on the fifth nerve, and an involuntary respiratory one, dependent on the portio dura ; also, that in the first instance he attributed the voluntary power of these muscles to the facial branches of the fifth, but that he had abandoned that idea, and acknowledged that what he had attributed to loss of motion was in fact due to loss of sensation. In the work adverted to he has taken new ground, and at the same time reiterates his first opinion with regard to the existence of the two distinct contractile powers in the muscles of the face, and attributes to the buccal nerve that influence over their voluntary motion which he had before referred to the infra-orbital, &c. Thus, " but finding that the connexion between the motor root and the superior maxillary nerve proved to be only by cellular texture, and con- sidering the affirmation of M. Magendie and those who followed him, that the infra-orbitary branch had no influence upon the lips, I pro- secuted with more interest the ramus buccinalis labialis," — the buccal nerve, — " and nobody, I presume, will doubt that the distribution of this division confirms the notions drawn from the anatomy of the trunk, not only that the fifth nerve is the manducatory nerve as it belongs to the muscles of the jaws, but also that it is distributed to the muscles of the cheek and lips to bring them into correspondence with the motions of the jaws." To the point at issue the writer has directed particular atten- * 1833, p. 261. 304 FIFTH PAIR OF NERVES. tion : he has made repeated dissections of the distribution of the lesser packet of the nerve both in the horse and in man, and after a care- ful examination, it appears to him that Mayo is essentially right, though the view given by him does not exactly agree with the arrange- ment of the nerve as found by the author either in the horse or in man. In the former the masseteric branch arises from the lesser packet by two fasciculi, one of which runs round the ganglionic portion of the third division of the nerve, and joins the other and larger fasciculus before it : the facial portion of the buccal nerve appears to the author to be purely gan- glionic, but the root of the nerve in part appears to be derived from the non-ganglionic portion and is not ; and in part may or may not be considered to proceed from it. It is entangled at its origin with fasciculi of that por- tion, more or fewer of the filaments which it derives from the ganglionic packet passing be- tween and even interlacing with fasciculi of the non-ganglionic ; but by a patient proceeding these may be traced to their proper source, and the nerve be extricated from this connexion. It is, however, difficult to accomplish it at times, at others it is sufficiently easy. Again, one or more branches of the non-ganglionic portion accompany the buccal nerve for some distance, connected to it more or less intimately, but apparently not enclosed within the same sheath, though communicating with the nerve by fila- ments from a ganglionic fasciculus and separa- ble without injury to either. These branches, however, separate from the nerve again for dis- tribution before it leaves the zygomatic fossa ; they may be considered, or not, to belong to the nerve, but they do not affect the question with regard to its facial portion ; and the author believes that the arrangement described is not uniform, the branches adverted to not always accompanying the buccal nerve. Again, on the one hand it has been already shewn that division of the portio dura on both sides deprives the facial muscles of all inde- pendent* contractile power, whether voluntary or involuntary ; and on the other, Mayo has found that irritation of the buccal nerve does not excite contraction in those muscles : the author has taken occasion several times to repeat the experiment of Mayo upon the latter nerve after it had emerged upon the face, and he has not succeeded in obtaining contraction of the facial muscles thereby, while the strug- gles of the animal, excited by the irritation of the nerve, proved it to be one of exquisite sen- sibility. It appears then to the author impos- sible to admit that the facial muscles either possess two contractile powers dependent on distinct nerves, or that they derive any volun- tary power from the fifth. It is extraordinary that Magendie, who was the first to detect the error into which Bell had fallen with regard to the influence of the infra- orbital nerve over the motions of the muscles * This expression has been used because the muscles may be still excited to contraction by irri- tation of the portion of the nerve connected with them. of the face, and has, according to his own report, divided the portio dura on animals, should, notwithstanding all that has been written upon the subject, have adopted the opinion that the muscles of the face are en- dowed with the two distinct faculties of motion, one of which is derived from the fifth. His view will be found at page 703-4, Anatomie des Systemes Nerveux, &c, and the opinion there expressed is implied in a note at page 191, Journal de Physiologie, t. x. In the former he says, " Now Mr. Charles Bell in England and M. Magendie in France by cutting the facial nerve have paralyzed the respiratory motions of all the side of the face correspond- ing to the nerve cut. But the muscles which receive at once filaments from the facial nerve and from the fifth pair were paralyzed only in their action relative to respiration and to the expression of the physiognomy." The influence of the fifth nerve upon the tac- tile sensibility of the parts with which it is con- nected has been discussed : its influence upon their ordinary sensibility also requires notice. From the preceding details it appears esta- blished that it is to the same nerve that this property also of the parts in general is due; but there is reason to believe that the nerve exerts a more extended control over this faculty than was at first supposed. At the commence- ment of the inquiries into the functions of the nerves of the face, the opinion generally held was that the facial nerve — portio dura of the seventh pair — was devoid of sensibility. Fur- ther observations, however, showed that this conclusion was erroneous, and that the insen- sibility to any injury done to the nerve in question manifested by the subjects of experi- ment, and from which the inference had been drawn, was only apparent, and to be referred to the constitution of the individual animal or of its species. The sensibility of the facial nerve having been established, a question arose, whether that property was independent and proper to it, or whether it was conferred by another ? Those who first observed the sensi- bility of the nerve adopted the former opinion ; but considerations entitled certainly to much weight led Eschricht to suspect that the facial nerve is not endowed with independent sensi- bility, and that the sensibility which is manifested when it is injured is conferred on it by the fifth nerve. In order to determine the question he performed a series of experiments in which he divided the fifth nerve within the cranium upon one side after having opened the cavity and removed so much of the corresponding hemi- sphere of the brain as was necessary for the accomplishment of his purpose : the facial nerve of the same side was then exposed, and its properties tested. The faculties of the animal are so little affected by the removal of the brain, that the result of the experiment seems free from objection, while all influence of the fifth nerve upon the sensibility of the facial or other parts must be destroyed. In his first successful experiment irritation of the facial excited spasms of the lips, and also in- dications of suffering so decided that a doubt FIFTH PAIR OF NERVES. 305 could not be entertained : the fifth nerve had also been fairly divided: thus far, therefore, his conjecture was disproved. Pursuing his inquiry still further, he found in his next experiment that no indication whatever of pain was manifested by the animal on irritation of the facial on the side on which the fifth nerve had been cut ; but in two succeeding experi- ments he ascertained that while irritation of the nerve anterior to the meatus auditorius pro- duced no other effect but spasms of the nasal and labial muscles, when exerted posterior to that point it excited manifest evidence of suf- fering : this latter circumstance he accounts for by the communications of the posterior part of the facial with other sentient nerves besides the fifth, and he has come to the conclusion that the former nerve is not endowed with independent sensibility, but that it derives the property from the fifth and other sentient nerves : this ques- tion, however, requires further investigation.* Relation of the fifth pair of nerves to the special senses. — The organs of the special senses are in the higher classes and in the case of smell, sight, and hearing, each supplied with nerves from at least two sources. Besides the particular nerves, which are generally consi- dered to be the source or medium of the spe- cial sense, they are furnished with branches from the fifth pair; and a question must, at the outset, be asked in regard to the two nerves derived from these different sources, as to which is to be considered the proper nerve of the peculiar sense enjoyed ? In connexion with the two separate nervous supplies, it is also to be observed that each organ enjoys two kinds of sensibility, viz. the special sensibility, through which sensations of the particular sense are received, and the general sensibility, in which the several organs of the body partici- pate, and which is the medium through which impressions of contact are conveyed. The exis- tence of the special sense, the coincidence of the particidar nerve, the impairment or loss of the special function uniformly consequent upon the injury or destruction, whether by disease or otherwise, of that nerve ; and the community both of function and distribution, displayed by the nerve from which the organs of the senses are in common supplied, have led physiologists generally to the conclusion that in each case the particular nerve is the medium of the special sense, and that the fifth nerve confers upon the organs of the spe- cial senses general sensibility only. The con- clusion thus commonly adopted has been at different times called in question : thus Mery and Brunet, in 1697, denied to the nerves of the first pair the function of smell, and attri- * Eschricht, de functionibus nervorum faciei et olfactus organi, Hafn. 1825. | The superficial tem- poral nerve doubtless contributes mainly to supply sensibility to the posterior twigs of the facial : but so much difficulty do some see in satisfactorily accounting for the sensibility of the portio dura, that they find it convenient to discover two roots of oiigin, and a ganglion on one, thus reducing it to the class of compound nerves. See Arnold, Icones capitis nervorum ; also Gaedechcns, nervi facialis physiologia et pathologia. — En.] VOL. II. buted this sense to the fifth nerve * The ques- tion of the connexion between the fifth nerve and the special senses is one of much difficulty, and probably we are not as yet in possession of sufficient data from which to draw a positive conclusion upon it when viewed in all its bear- ings. It resolves itself into three: 1. how far the nerve may be concerned in the perception of special sensations in those cases in which nerves, considered to be specially intended for their perception, exist: 2. how far its co- operation or influence may be necessary to enable the special nerves to fulfil their func- tions: 3. how far it may be capable of taking the place of those special nerves, and of be- coming, under certain conditions, media of perception to sensations, for which, in other cases, peculiar nerves are conferred. We shall review the relation of the nerve to the several senses in succession, bearing in mind the three points to which our attention is to be directed. That it is a medium of perception in the case of two senses, viz. touch and taste, is already so universally acknowledged that it is unneces- sary to dwell upon the point. The importance of the fifth nerve in the three other senses of smell, sight, and hearing, has been advocated by several physiologists, and more particularly by Magendie, who ap- pears disposed to view the fifth nerve as the source or medium of all the three. His appli- cation of this doctrine, however, has reference more particularly to the sense of smelling, upon which he has performed a series of expe- riments, of which the following is a summary : he destroyed entirely the olfactory nerves within the cranium, and he found the animal still sensible to strong odours, such as ammonia, acetic acid, essential oil of lavender. The sen- sibility of the interior of the nasal cavity had lost nothing of its energy; the introduction of a stylet had the same effect as upon a dog which had not been touched. This experiment he performed several times, and always with the same results. He next divided the fifth nerves within the cranium, of course before they had given branches to the nostrils, and found all trace of the action of strong odours to disappear. He hence concluded that smell, in so far as pungent smells are con- cerned, is exercised by the branches of the fifth pair, and that the first is not concerned in the function. To this conclusion he himseli starts the objection that the agents used are not odours, properly speaking, but chemical, pun- gent, irritating vapours, and that by the section of the fifth we destroy not the sense of smell, but only the sensibility of the membrane of the nose to these irritating vapours, and he admits the force of the objection with respect to some of the vapours alluded to ; but he denies that it will apply to the oil of lavender or that of Dippel, the effect of which in the experiments is the same. In order to remove the difficulty he destroyed the olfactory nerves of a dog of particularly fine nose, and then enclosing por- tions of food of various kinds in paper, he * See Journal Complementaire, v. 20. x 306 FIFTH PAIR OF NERVES. presented them to the animal, and it always undid the paper and possessed itself of the food ; but, he adds, " I do not regard this ex- periment as satisfactory, because in other cir- cumstances it appeared to me to want smell to discover food which I put near him without his knowledge" (a son insu ). However, the latter circumstance is overlooked by Magendie, and his conclusion is, " une fois le nerf trifa- cial coupe, toute trace de sensibilite disparait, aucun corps odorant a distance ou en contact, les corrosifs memes n'affectent plus en aucune facon la pituitaire."* Doubtless this conclu- sion is qualified by another immediately suc- ceeding, " that does not prove that the seat of smell is in the branches of the fifth pair; but it proves at least that the olfactory nerve has an indispensable need of the branches of the fifth pair to be able to enter into action ; that it is devoid of general sensibility, and that it can have only a special sensibility relative to odorous bodies. "\ The latter must be ad- mitted to come, if not quite, at least very near to the general opinion, but it is altogether at variance with the former, and one is rather at fault for the author's precise meaning. Refe- rence to later writings, however, leaves no doubt upon that point. In the conjoint work of Desmoulins and Magendie (1825) upon the nervous system of the vertebrata, besides other similar passages, will be found the following: " La cinquicme paire, par ses branches nasales dans les mammiferes, et par ses branches pro- pres a la cavite pre-oculaire des trigonocephales et des serpents a sonnettes, est done l'organe de l'odorat."J Notwithstanding the weight of Magendie's authority, a careful review of the matter will not permit us to assent to this con- clusion, and compels us to avow not only that it is not proved, but that the premises justify a contrary one. In the first place it is not war- rantable to call the effluvia of ammonia or acetic acid odours : they are no more odours than the fumes of muriatic or nitric acid ; and, though aware of the objection, he still calls them odeurs fortes, and bases his inference upon their operation. But he says the objec- tion does not apply to oil of lavender or the animal oil of Dippel : this, however, is but an assumption at variance with fact; in the human subject these agents may act feebly upon the sensibility of the membrane of the nostrils, and may not appear to possess irritating properties ; but this will not prove that they act similarly upon animals, whose organ of smell is more sensitive than that of man, and accordingly Dr. Eschricht,§ who combats the opinion of Magendie, has found that, on application to the nostrils of those animals upon which the experiments of Magendie have been performed, they produce all the same effects which am- monia or nitric acid does. In the second place his experiment of presenting food to a dog, whose olfactories had been destroyed, enclosed * Journal de Physiologie, t. iv. p. 306. t Ibid. t T. ii. p. 712. § Journal de Physiologie, t. »i. p. 350. in paper, and in which the animal undid the paper, upon his own showing not only does not justify his inference, but, so far as it reaches, proves the contrary. To establish his position the animal must have discovered the food by smell, without knowing that it was in the paper; but it is manifest, from Magendie's own relation, that when the animal undid the paper, it knew, or was led by some circum- stance to expect the food to be in it ; but that when it was not already aware or in expecta- tion that the food was near it, it did not dis- cover it. To the writer it seems that the na- tural inference from the experiment, as related, is that the animal's proper sense of smell de- pended upon the olfactory nerves, inasmuch as it did not display fair evidence of its presence after their destruction, and that the sensibility displayed by the membrane of the nostrils after the destruction of these nerves, and dependent upon the fifth, has reference only to those im- pressions which are objects of tactile or general sensation, but not of the special sense. At the same time, however, that we express our dissent from Magendie with regard to the nervous connexion of the proper sense of smell, it must be admitted that his researches posi- tively indicate a distinction between the media of perception in the case of different agents operating on the olfactory organ, which it has been too much the habit to regard as pro- ducing their impressions all through the olfac- tory nerves : they have gone a considerable way in demonstrating the separation of those media; a result which is made complete by the conti- nuance of the simple sense after the loss of the influence of the fifth nerve consequent upon disease : further, they indicate that sensations derived through the organ of smell are less simple than they are usually accounted ; that they may be, and probably are for the most part, compound, resulting from the combina- tion of impressions made upon the two senses thus shewn to be enjoyed by the organ. Magendie's view has been adopted, and an endeavour made to corroborate and establish it by Desmoulins in ' Reflexions' upon a case communicated by Beclard, and published in the fifth volume of the Journal of Physiology. The case is that of a patient, in whom the olfactory nerves and their bulbs were de- stroyed by the growth of a tubercular disease from the anterior lobes of the brain ; " yet he took snuff with pleasure, appeared to distin- guish its different qualities, and was affected disagreeably by the smell of the suppuration of an abscess with which one of his neighbours was afflicted." From this case, from that of Series, related elsewhere, and the experiments of Magendie viewed in connexion, Desmoulins has adopted the opinion that " the nerves and lobes called olfactory are alien to the sense of smell, or at all events co-operate so little in it, that the sense continues to be exerted without them ; that, on the contrary, this sense resides essentially in the branches of the fifth pair, which are distributed to the nostrils." Serres' case has been discussed elsewhere; that of Beclard appears at first unanswerable ; but FIFTH PAIR OF NERVES. 307 how will it appear after the qualification by which it is followed has been perused ? " I owe it to truth," he says, " to add that these last statements were not collected till after the dissection, and that they were gathered from the patients of the ward." Such an admission manifestly destroys the value of the case : evi- dence obtained only after the individual's death, so little marked as during his lifetime to have been overlooked, and relating to a question at once so obscure and delicate, can hardly fail to be imperfect; but admitting that the patient did relish and distinguish between different kinds of snuff, and that he was disagreeably affected by his neighbour's ailment, what then? The chief property of common, if not of every snuff, is pungency and not odour, and the per- ception of pungency is not the function of the olfactory nerve; and one may be as disagree- ably affected by a disgusting sight as by a dis- gusting smell, and the patients of the ward not make any distinction between the senses af- fected, until taught by the inquiries made that it must have been that of smell. And if the case just quoted prove the existence in the organ of smell of a sensibility to the impres- sion of volatile agents independent of the ol- factory, and conferred by the fifth nerve, the existence of another equally independent of the latter is satisfactorily established by the continuance of smell in those cases in which the faculty conferred by the fifth nerve has been lost through disease. This may be seen from reference to the case furnished by Beclard, and advanced by the very advocates of Magendie's doctrine in support of it; but the fact is still more strongly established by the case some time since published by Mr. Bishop, in which, though the fifth nerve was completely destroyed by the pressure of a tumour within the cra- nium, and both the ordinary and tactile sensi- bility of the same side of the face and its cavi- ties was in consequence altogether lost, the sense of smell continued unimpaired. In a case of disease of the fifth nerve which the writer has witnessed, the patient did acknow- ledge the perception of certain odoriferous agents ; but judging from it alone, he could not say that smell was not impaired ; on the contrary it seemed very much so, inasmuch as the patient denied at first any perception of the impression of several agents accounled odorous, and when he did say that he smelt these, it was not of himself, nor until he had been particularly questioned, and then he said it was * up in his head' that he felt the sensa- tion, and positive must take precedence of nega- tive evidence. Further, it is very likely that in the case of sensations, themselves neither dis- agreeable nor acute, the vividness of which may depend very much upon association with other and more acute ones, the former may be disregarded where the latter have been lost, and hence the rashness of inferring that brutes have lost certain faculties, because in the course of experiments they do not by the exercise of these give evidence of their existence. The fact of the absence of olfactory nerves in the Cetacea as established by Cuvier has also led some to the conclusion that the proper faculty of smell may be capable of being transferred at least to the fifth ; but until the faculty has been proved to exist in such case, the inference is manifestly not warranted by the premises. It appears then that there is a distinct per- ceptive faculty enjoyed by the nostrils, inde- pendent of the fifth and dependent on the olfactory nerve; that we possess no positive evidence of the latter nerves being in any case the media by which this peculiar perception is recognized, but that they serve for the recogni- tion only of impressions of contact, pungency, or irritation. 2. Relation of the fifth nerves to vision. — • That in all animals having at once the faculty of vision and an optic nerve, the latter is in- dispensably necessary to the exercise of the former cannot be denied : — disease or division of the nerve is uniformly attended by loss of the function ; but some circumstances coun- tenance the opinion that the fifth nerve pos- sesses a more important connection with vision than may at first appear. 1. Injury of the frontal and certain other branches of the fifth nerve has been long accounted among the causes of amaurosis. 2. Maj;eiidie has found that " on division of the two ' fifth ' nerves upon an animal it seems blind." 3. The fact which countenances most strongly the opinion that the fifth nerve is concerned directly in the function of vision is derived from com- parative anatomy. It has been stated that in certain animals a special optic nerve is wanting, and the ocular nerve is derived from the fifth pair. Of this it appears universally admitted that the proteus anguinus is an instance; its eyes are situate immediately beneath the epi- dermis, which is transparent * in front of them ; the optic nerve is wanting,-)- and the only nerve received by the eye is a branch of the second division of the fifth. \ Whatever vision, there- fore, may be enjoyed by this animal, and according to Carus§ it is considerable, must be exerted through the medium of the fifth nerve. Among the mammalia also are several animals which appear to be in the same, or nearly the same state ; but anatomists are not agreed on the point : the absence of a special optic nerve in the mole was announced by Zinn, || who shewed that its place was taken by a branch of the fifth. Carus and Treviranus, however, maintain that the optic does exist in the animal, but that it is very minute, grey, and capillary ; that in the same proportion the fifth nerve is large, and that its second division at its exit from the cranium gives off a branch, which enters the globe of the eye, and according to the former concurs in forming the retina.lf Serres again positively denies the existence of the optic nerve in the mole, and maintains that these anatomists are mistaken ; he states that he has sought the * Serres. t Treviranus, Serres. X Ibid. § Comparative Anatomy. [I De differentia fabricae oculi humani et brntorum. Tl Journal Complementaire, vol. xv. x 2 308 FIFTH PAIR. OF NERVES. nerve with the greatest care in thirty or forty of these animals, and never succeeded in finding it; and also in confirmation thereof that the optic foramen is wanting in the sphenoid bone. According to him several other of the mammalia are similarly constituted, viz. the mus typhlus, the mus capensis, the chrysochlore, and the sorex araneus. Of these the mole, the mus capensis, and the sorex arensis decidedly enjoy vision, the first ac- cording to the observations of Geoffroy St. Hilaiie and Cuvier ; the second according to those of Uelalande, and the third according to Series himself ; and if his view of the anatomical disposition of their ocular nerve be correct, the fifth nerve must in them also take the place of the optic and serve as the medium of sight. Treviranus, though he maintains the existence of a special nerve in the mole, yet says, from the disproportion of the optic and the ocular branch of the fifth, that in that animal the latter ought or must have to fulfil in vision more important functions than the optic nerve.* When to these facts we add the view of the nervous connections of the senses in invertebrate animals advocated by Treviranus, viz. that the nerves of the senses in them are all branches of the fifth pair, the general proposition seems sufficiently probable, viz. that the fifth nerve is capable of acting as a medium of perception to impressions of light. But on the one hand, until it be proved what the exact nature of the optic faculty is which animals devoid of a special optic nerve possess, the question must be held to be undecided. It may be that the faculty is different in the two cases ; that where the special nerve is absent, the faculty may amount, as suggested by Treviranus, to no more than a mere perception of light, and that the im- pression is then not visual, but only one of ordinary sensibility. Such a distinction, in the sense in which that term is understood in reference to the higher animals, is easily conceived, and indeed is demonstrable from the influence of light upon an inflamed or irritable eye, and if such a distinction do naturally exist, the apparent anomaly presented by animals being sensible of light and seeming to enjoy vision without a special optic nerve will be removed, while such a faculty may suffice fully for the condition of the animal. Again, the evidence in favour of the opinion that the fifth is directly concerned in vision where a special nerve exists, seems altogether insufficient. In the first place, though in- juries involving the frontal or other branches of the fifth nerve may induce amaurosis, it remains to be proved that the injury of the nerve is the cause of the disease, and that this did not rather arise from the effect of the injury upon other parts concerned in vision; a view which is greatly confirmed by the fact that the' mere section of the nerve has not been found to occasion any such affection of vision. In the second place the experiments of Magendie are far from satisfactory. In * Ibid. vol. xv. p. 210. order to determine the influence of the fifth nerve upon vision, he performed the following experiments, from which he inferred that the section of the fifth nerve destroys sight without abolishing entirely all sensibility of the eye for light, and suggests in explanation either that the fifth is the medium of perception, or that it is necessary to enable the optic to act. After having divided the fifth pair on one side in rabbits, he threw suddenly upon the eye the light of a wax candle, and no effect was produced ; the same being tried upon the sound eye, the only effect produced was move- ments of the iris. Under the impression that this was not sufficiently intense, he tried that of a powerful lamp, but, even with the as- sistance of a lens, the result was the same. He then tried the experiment with solar light, and by making the eye pass suddenly from the shade to the direct light of the sun, an impression was produced and the animal im- mediately closed its eyelids. Such data cannot be admitted as sufficient to justify the inference that vision is destroyed by the section of the fifth nerve. In the first place it is to be recollected that the experiment was made upon rabbits, in which Magendie has elsewhere told us that section of the fifth nerve produces strong con- traction of the iris, consequently great dimi- nution of the size of the pupil : and of what value, then, is the result that, under the in- fluence of the light of a candle or a lamp, an impression was not made sufficiently powerful to cause the animal to give evidence of it? In the second place the animal did, under all the disadvantages, give sufficient evidence that its vision was not destroyed ; there is, therefore, no reason for the conclusion drawn from the experiment related. On the other hand. Mayo has found that the fifth nerve may be divided within the cranium in the cat and pigeon, and vision continue unaffected; which circumstance shows that the apparent loss of vision in the rabbit was owing to the great contraction of the pupil, while according to Magendie's statement there does not remain any trace whatever of sensi- bility to the impression of light in the eye after the section of the optic nerve. We must, then, conclude that the optic nerve is the proper medium of perception to visual im- pressions, and that the co-operation of the fifth nerve is not even necessary to enable the optic nerve to fulfil its function. As the instrument of the general sensibility of the structures of the eye, however, the fifth nerve may be the channel through which impressions not visual, though perhaps excited by an agent of vision, viz. light, may be conveyed. The conclusion thus drawn from experimental physiology is fully confirmed in man by the history of those cases in which the influence of the fifth nerve has been lost from disease : of these two have been adduced by Bell in the Philosophical Transactions for 1823, one from the observation of Mr. Crampton, the other from that of Dr. Macmichael, in which the surface of the eye was totally insensible, whilst vision was entire ; and another, still FIFTH PAIR OF NERVES. 309 more remarkable, has been reported by Mr. Bishop,* in which the functions of the fifth nerve seemed altogether obliterated by the pressure of a diseased growth within the cranium, and yet the patient saw distinctly to the last, the only derangement which oc- curred in the function of vision being the loss of the power of distinguishing colours, which appears sufficiently accounted for by a certain degree of pressure exerted by the tumour upon the optic nerve. Magendie endeavours to support his views upon this and other points connected with the properties of the nerve by reference to a case reported by Serres, which appears very inadequate, and will be discussed by-and-bye. Influence of the fifth nerve on hearing. — The great affinity between the sense of hearing and that of touch renders it more easy to conceive how hearing might be excited through the medium of the fifth nerve. As we have seen that the ocular nerve in certain animals is a branch of the fifth nerve, so is the auditory. Among the cartilaginous fishes there are several instances in which this occurs. The origin of the auditory nerve from the fifth in fishes was first announced by Scarpa,-)- and by him sup- posed to apply to fish generally. This view is combated by Treviranus:J it is admitted in part by Serres ; he states that in osseous fishes the auditory nerve is united at its in- sertion with the fifth; in cartilaginous fishes, that thp auditory is sometimes confounded with th^ fifth, sometimes separated distinctly enough, as in the raia'clavata. From his own observations the writer would say, that in the bony fishes the two nerves cannot be said to be united or to arise the one from the other, but only to have a common superficial attach- ment to the medulla oblongata ; and from the analogy of the same nerves in the higher classes of animals, he would not admit, without further proof, a common superficial attachment as establishing identity of ultimate connection with the encephalon. As to the cartilaginous fishes, it appears to him that Serres has fallen into an error with regard to the connection of the auditory nerve. It appears to the writer that the fifth and the auditory are con- founded in the raia clavata as plainly as in any other individual of the class ; the posterior ganglionic fasciculus of the fifth and the auditory nerve form one trunk for a distance of some lines after leaving the medulla ob- longata ; they are at all events enclosed within the same sheath : § but whether they are to be regarded as branches of a common trunk or not, it is difficult to decide. The weight of naalogy is certainly opposed to a conclusion * Medical Gazette, vol. xvii. t De Audita et Olfactu. 1 Journ. Compl. § Serres seems to have overlooked the fact that there exist two ganglionic fasciculi in the raia clavata ; that he has assumed the anterior fasci- culus to be the fifth, and described the posterior, with which the auditory is connected, as the auditory and facial nerves : the error will be manifest upon tracing the distribution of the fasciculus. in the affirmative ; and, though this were ad- mitted, a difference between the auditory and the other branches of the fifth (as supposed) must still be admitted, inasmuch as the auditory separates from the nerve before the occurrence of the ganglion, and has not itself a ganglion. On the other hand the auditory may be se- parated from the rest of the nerve, after the division of the common investing membrane, with little or no laceration of fibres. Still it may be asked why, if they be distinct nerves, are they united into one trunk? The opinion that the fifth nerve holds an important in- fluence over the sense of hearing derives support from the circumstance, that in most, if not all, the cases of disease of the nerve, the sense of hearing becomes impaired, though not obliterated. The last question proposed to be considered with reference to the functions of the fifth nerve is its connection with nutrition. The opinion that the nerve controls the nutrition of the parts which it supplies has been advocated by Magendie, more particularly with regard to the eye. It has been already stated that we are indebted to this writer for information in regard to results of the division of the entire trunk of the nerve within the cranium. Of these the most prominent is the entire loss of sensibility on the same side of the face, and in regard to the eye especially, loss of sensibility in the conjunc- tiva, upon which the most irritating chemical agents then produce no impression. These immediate effects of the section were followed by others not less remarkable : on the next day the sound eye was found inflamed by the ammonia, which had been applied to it, while the other presented no trace of inflam- mation. Other changes, however, supervene. The cornea of the eye of the side on which the section is made, twenty-four hours after- wards begins to become opaque ; after seventy- two it is much more so ; and five or six days after it is as white as alabaster. On the second day the conjunctiva becomes red, inflames, and secretes a puriform matter. About the second day the iris also becomes red and in- flames, and false membranes are formed upon its surface. Finally the cornea ulcerates, the humours of the eye escape, and the globe contracts into a small tubercle. In endeavouring to ascertain the cause of these changes, Ma- gendie, on the supposition that they might be owing either to the continued exposure of the eye to the air or to the want of the lachrymal secretion, divided the portio dura in one rabbit, the effect of which is to destroy the power of closing the eyelids ; and from others he cut out the lachrymal gland ; but in neither case did opacity of the cornea suc- ceed. The sequence of the effects mentioned after the section of the nerve might naturally lead us to infer that the loss of nervous in- fluence gives rise to them. But such is not the inference drawn by Magendie, nor indeed can it be admitted : absence or subtraction of an influence cannot be directly the cause of an alteration in the condition of an object 310 FIFTH PAIR OF NERVES. otherwise than by allowing it to come or return to a state from which it is preserved by the presence of the influence ; and there is no good reason, either theoretical or experimental, for believing that the state induced in the case under consideration is one in which the eye would necessarily be, which, in fact, would be natural to the organ but for the restraining influence exerted through the fifth nerve. It is easy to imagine that the absence of such an influence should render a part slow to take on any vital action ; though even this, until proved, is an assumption — an assumption which we are induced to adopt from the fre- quency with which sensation and pain are found associated with the establishment of cer- tain vital processes, more particularly inflam- mation, but which is, on the other hand, con- tradicted by the readiness with which inflam- mation and its consequences are excited in parts whose nervous faculties are impaired or destroyed by agencies which make little or no impression when those faculties are retained, and which must be demonstrated before admit- ted, since it is manifest from the occurrence of that process after the destruction of all trans- mitted influence at least, that the principle — the main-spring of it must reside elsewhere; and hence that, if in the natural state the nerve influence the process at all by means of such a property, it can be only in the character of a secondary and controlling power. It does, however, seem proved by the result of Magen- die's experiment, that the interruption of the influence did retard the inflammatory process, inasmuch as the eye, on the side of the undi- vided nerve, was very actively inflamed the day after the application of ammonia to it, whilst the other eye did not present any trace of in- flammation ; a circumstance by the way diffi- cult, if not impossible, to reconcile with the doctrine that the process of inflammation is directly influenced in either way, whether posi- tively or negatively, by the power of the nerve ; and further, that the division of the nerve should diminish the vital powers of the eye, and thereby render it less able to resist the effects which inflammatory action tends to pro- duce. But indeed there does not appear any reason for admitting that the alterations which took place in the condition of the eye were produced directly by the loss of nervous influ- ence. Having, as he conceived, disproved, by the experiment related, the idea that the alte- rations were owing to the continued exposure of the eye to the air, or to the want of the lachrymal secretion, — the only other causes which appear to have occurred to him, — Ma- gendie arrived at a conclusion the opposite of that just mentioned, and adopted the opinion that the phenomena " depend upon an influ- ence purely nervous"* exerted by the fifth nerve upon the eye, — " an influence independent of the connection of the nerve with the spinal mar- row, "f — an influence " proper to the nerve, * Anatomie des Systemes nerveux, &c. t. ii. p. 716. t Journal de Physiologie, p. 304. which has not its source in the cerebro-spinal system, and which is even the more energetic, the farther we remove from that system to a certain distance," of which the following is his proof. " Alterations of nutrition in the eye are the less complete, the less rapid, as we remove farther from the point of branching of the nerves of the fifth pair, and as we cut, within the cra- nium, the fasciculus of origin the nearer to its insertion ; finally, the section of the nerve on the margin of the fourth ventricle no longer produces any alteration in the state of the eye." * In this view there are plainly two posi- tions advanced, viz. that the nerve does itself exert a proper and independent influence upon the nutrition of the eye, and that it is the sec- tion of the nerve which causes the exercise of that influence, or, to use his own words, which is the cause of the inflammation, &c. That the occurrence of the alterations in the eye, in the case in question, is not due to an influence exerted by the brain through the nerve, and that it must proceed from another cause, and that not dependent upon the connection be- tween them, is manifest, since it is consequent upon the interruption of that connection ; and therefore, if the nerve do possess the supposed influence, it must be a proper and independent one : but are we, therefore, to infer that the nerve does exert such an influence upon the organ ? It appears to the writer that we cannot : for can we suppose that the nerve is endowed with a property to be displayed expressly under cir- cumstances, which it is fair to say were not contemplated in the establishment of natural laws, viz. in cases of mutilation? or is it possi- ble that a separate influence can exist in the nerve and increase in energy in proportion as the nerve is curtailed ; for the nearer the section is made to the eye, the more remarkable are the effects ; or if any other proof that the nerve does not possess such an influence be wanting, can we suppose that it is possessed for the eye and not for the other parts to which the branches of the nerve are distributed ? Why does not inflammation forthwith assail the nostrils, the mouth, and cheeks upon the mere section of the nerve,f as well as the eye ? Manifestly be- * Op. cit. ibid. t It is stated by Professor Alison, Outlines of Physiology, p. 147, that inflammation, ulceration, and sloughing are produced sometimes on the mem- brane of the nose and on the gums by section of the fifth nerve, "as was first ascertained by Magendie." The only passages approaching at all to this state- ment, which the author has found in Magendie's writings, are at page 181, Journal de Physiologie, t. iv, and page 717, Anatomie des Systemes Ner- veux, &c. Desmoulins et Magendie, t. ii. In the first he says, " when a single nerve is cut, there appear alterations in the nostrils, the mouth, the surface of the tongue on that side ; the half of the tongue becomes whitish, its epidermis is thickened, the gums quit the teeth ; the alimentary matters sink into the intervals which are formed ; probably because the animals having no longer their atten- tion attracted by the sensation of the tendency of the matters to pass between the teeth and the gums, push them thither without perceiving it;" and in the second, " a part of the broken food re- mains on that side, between the teeth and the cheek, and its contact terminates by ulcerating the FIFTH PAIR OF NERVES. 311 cause no such influence exists ; and indeed the data upon which it has been assumed, instead of proving the position, leave it precisely as it was ; for insomuch as the occurrence of the phenomena upon the section prove the exist- ence of the influence of the nerve, in the same degree does the absence of the phenomena upon the section of the nerve disprove it. But was the inflammation caused by the section of the nerve? This question, which cer- tainly ought to have been determined satisfac- torily before a theory had been founded upon the assumption, appears to the writer to have been decided too hastily in the affirmative. If the section were the cause, no sufficient reason can be assigned why it should occasion inflam- mation in one part, to which the nerve is distri- buted, and not in another, yet such is the case; the eye is the only part in which inflammation supervenes, either so uniformly or so quickly as to afford any ground for attributing the pro- cess to the section. In the second place, were the section the real and essential cause, it can- not be supposed either on the one hand that non-essential circumstances could influence, or at all events prevent the effect, or on the other, that they could produce it. Now it will pre- sently appear that both the one and the other may take place ; and a comparison of Magen- die's experiments and their results would alone suffice to shew that the real cause is to be sought elsewhere than in the section of the nerve. Magendie divided the nerve in three different situations ; first, through the temporal fossa; secondly, within the cranium, between the Gasserian ganglion and the pons Varolii ; and thirdly, at the margin of the fourth ventri- cle ; and his own general account of the results, which has been already cited, is as follows : *f those alterations in the nutrition of the eye are the less complete, the less rapid, as we recede more from the point of branching of the nerves of the fifth pair, and as we cut, within the cra- nium, its fasciculus of origin the nearer to its insertion ; finally, the section on the margin of the fourth ventricle no longer produces any alteration." It is plain, then, that the nerve may be cut, and the changes in the eye ensue or not, according to circumstances to be yet explained. On the other hand, that effects similar in kind, if not equal in degree, may be produced by circumstances not essential to their production, — according to the doctrine main- tained, but incidentally associated with the supposed cause, — that such effects may be pro- buccal membrane." In neither of those extracts is there mention of inflammation or sloughing ; and the ulceration which is mentioned, is attributed to another cause than the section of the nerve. On the other hand, the writer has frequently divided the lingual branches of the fifth nerve and pre- served the animals for months afterward, and he has been unable to detect any change in the condi- tion of the tongue, except this, that in some the tip of the organ, from being allowed to remain between the teeth, and thus to be exposed to injury, ulce- rated, and this continued until the tip was re- moved, when the extremity of the organ healed, and it appeared to be in all other respects as before. duced by such circumstances, when dissociated from the other and operating separately, the author feels justified in asserting, from the re- sult of some experiments lately made by him- self, which lead to the conclusion that similar effects may be produced without the section of the nerve at all, and that an injury in the vici- nity of the orbit may excite them though nei- ther the trunk of the fifth itself, nor its ophthal- mic division have been divided. In an endea- vour to determine the nerves of taste, he under- took the removal of the ganglion of Meckel from the dog ; in order to accomplish this it was necessary to displace the zygoma and the coro- noid process of the jaw ; he attempted it seve- ral times before he succeeded, and failed at different stages of the operation ; but in almost every instance the eye of the same side became bleared within the next two days. The animal kept it nearly closed : a whitish puriform mat- ter was discharged from it, in quantity propor- tioned to the case, which concreted between the lids ; and the animal made no attempt to remove the matter or cleanse the eye : the affec- tion of the eye was always proportioned to the violence done, and abated with the inflamma- tion of the wound ; and in one of the instances in which the ganglion was removed, it actually produced opacity of the cornea, and ulceration in that structure, which continued after the lapse of more than a month from the operation ; yet most assuredly neither infra-orbital nor ophthalmic nerves had been divided. Thus, if, on the one hand, the nerve may be cut and the changes not ensue, on the other it may be left uncut, and the changes may occur. It may be objected that the effects here de- scribed fall very far short of those which took place in the experiments of Magendie. That they fall short of those which occurred on the division of the nerve in the temporal fossa is quite true, but it is equally so that they far ex- ceed those consequent upon the section at the margin of the fourth ventricle. The objection, therefore, would be devoid of weight, and if we suppose superadded to the violence already done when the nerves are not divided, the ad- ditional violence necessarily inflicted in the division of them, we shall have a ready expla- nation furnished of the higher degree to which the effects produced amount in one case than in the other. From the preceding considerations it appears to the author necessary to infer, that the changes which supervene in the eye after the section of the fifth nerve in certain cases, take place inde- pendently of the section, as the primary, imme- diate, or proper cause ; for were it otherwise, it cannot be supposed either that the difference of half an inch to one side or the other, as re- gards the point of section, could so influence the cause as to prevent or allow these changes, or that they could occur, even in degree, without it. How, then, are the phenomena to be ex- plained? It has been said by Magendie that they are less marked the more we recede from the point of branching of the nerve; but it is to be further observed, that, as we recede from the point of branching of the nerve, we recede 312 FIFTH PAIR OF NERVES. also from the orbit, the eye and its appendages, and in our operation for the division of the nerve we do less violence either in their vicinity or actually to them, until the operation is per- formed at such a distance from those parts, that they are not involved in the injury inflicted. Thus the nerve cannot be divided through the temporal fossa without great violence done to the parts in the vicinity of the orbit, and con- nected with the eye as well as the fifth nerve, as is evident from the result, and as has been explained elsewhere.* In the section be- tween the ganglion and the pons, the violence is inflicted at a part more remote than the former, from the orbit, &c, and here, according to his own account, the effect upon the eye was much less considerable. But the most re- markable fact is, that the alterations of nutrition are much less marked than in the former mode of experiment ; there forms only a partial in- flammation at the superior part of the eye, and the opacity which ensues occupies but a small segment upon the circumference of the cornea at the superior part ; and in the third case the parts injured are so far removed from the eye, — (in dividing the nerve on the margin of the fourth ventricle, Magendie exposed the parts by " opening the spinal envelopes between the occiput and the first vertebra,") — that the effects of the injury could not, under ordinary circum- stances, extend to it, and accordingly in it no alteration occurred. It would seem, then, that the great violencef inflicted, either in the vici- nity of the eye or actually to its appendages, constitutes the primary and immediate cause of the alterations which took place in the eye in the experiments under consideration. But it is likely they were the result of more causes than one, for there were also engaged in the experi- ments other agencies, the influence of which must have enhanced greatly that of the violence inflicted by the operation; thus, in the first place, in some of the instances at least, — and we have no evidence that it was not so in all, — ■ * It is hardly possible to conceive the section effected at the point and in the mode adopted, without a division of most of the nerves and vessels supplying the eye and its appendages. t A better idea of the injury likely to be inflicted in the experiment will be formed from a brief ac- count of the mode of conducting it. A lancet- pointed style is driven into tlie cranium through the temporal fossa and through its base, and when carried in to such depth as the experience of the operator teaches him to be sufficient, its point is moved upward and downward, until the loss of sensa- tion in the superficial paits assures him thatthe fifth nerve has been divided. After such a proceeding the question should rather be, what mischief has not been done than what has. There cannot be any assurance that, in the division of the fifth, the third, fourth, and sixth nerves with the branches of the sympathetic — nay, the optic itself — have not been involved : and if to this be added the almost cer- tainty of dividing the internal carotid artery, from which the supply of blood to the internal structures of the eye is directly derived, and the division of which causes the death of the greater number of the subjects of experiment, an amount of injury will be made out, quite adequate to account for the total loss of the eye, and which must reduce the influence of the fifth in producing it to a low degree indeed. a highly irritating agent was introduced, and, in consequence of the insensibility of the organ, probably in considerable quantity, into the eye; and in the second the eye was left under cir- cumstances more than enough to excite inflam- mation and to produce serious injury to it, though the organ had remained in full posses- sion of all those safeguards with which its sen- sibility and the sympathetic action established thereby between its several protecting appen- dages naturally endow it ; for " the eye was dry;" and " the eyelids were either widely open and immoveable, or else they were glued together by the puriform matters, which were dried between their margins ;" and an organ so circumstanced has abundant cause for inflamma- tion, independently either of nervous influence or of its absence. It may be said that Magen- die has proved that neither the open state of the eyelids nor the want of the lachrymal secre- tion is adequate to the effect. Admitting for a moment that he has, he certainly has not shewn that the combined influence of the two is inad- equate to produce it ; but the first position is by no means satisfactorily established : his mode of determining the question, whether the inflammation was excited by the eye remaining constantly open or not, was by the division of the portio dura, and his experiment has certainly proved that the effect of the section of that nerve will not excite inflammation in the eye, but no more ; inasmuch as such section does not produce a permanently open state of the eye : an eye so circumstanced will be closed during sleep, and even during the waking state it requires attention and experience in such observations to discover that the animal has lost the power of closing the lids by a muscular effort of those parts themselves ; for by the sud- den exertion of the power of retracting the eye, which inferior animals possess to a remarkable degree, the lids become nearly, if not quite, closed, and the animal appears to wink as well as before, while by rolling the eye the different parts of its surface are in turn brought beneath the lids, and thus no one part is ever left long absolutely uncovered. So great indeed is the power which brutes possess in this respect, that the author has seen a dog in which the portio dura had been divided on one side, presented for observation, and persons aware that the nerve had been divided, yet not able to disco- ver on which side it had been done, and even deny that the lids were paralyzed on either side, until something was approximated to each eye successively, when the uninjured eye was at once closed, but the other remained open, and the animal appeared looking at the object, which it was unable to exclude. It is obvious, then, that the question has not been and cannot be determined in this way. To the causes already enumerated must be added the loss of the nervous influence, for it is not intended, in what has preceded, to assert that the section of the fifth has no share in the production of the changes in the eye, but only that it is not the primary or essential cause of them. Indirectly it must contribute powerfully to produce and aggravate, or it may even excite FIFTH PAIR OF NERVES. 313 them ; for by destroying the sensation of the organ, it must leave it exposed to the unin- terrupted influence of many irritating agents, which naturally would excite inflammation, were it not that we are warned through the sensibility of the organ to avoid or to remove them, but in every such case they are the im- mediate, and the insensibility only the mediate cause of the effects produced, and such, it ap- pears to the author, is the part played by the section of the fifth in giving rise to inflamma- tion in the eye. It is further to be observed that the occurrence of inflammation in the eye in cases in which the influence of the fifth nerve upon it had been lost, had been noticed and given to the public by Bell prior to the publication of it by Magendie. In the Philo- sophical Transactions for 1823, (Magendie's memoir dates 1824,) Sir C. Bell reports the case of a patient under the care of his colleague Dr. Macmichael, in which the surface of the eye was totally insensible, and the eye re- mained fixed and directed straightforward, while the vision was entire. " The outward apparatus being without sensibility and mo- tion, and the surface not cleared of irritating particles, inflammation has taken place, and the cornea is becoming opaque ; thus proving the necessity of the motions of the eye to the preservation of the organ." And in the same volume he reports also a case from the expe- rience of Mr. Crampton of Dublin, bearing strongly upon the question, because it shews satisfactorily that the sensation of the organ, and consequently the influence of the nerve, may be obliterated, and inflammation not ensue until a stimulus have been applied, though the conjunctiva manifestly retained its susceptibility to the impression of that sti- mulus. Mr. Crampton's account of the case is as follows: " When she told me her eye was dead, as she expressed it, to be certain I drew my finger over its surface, and so far was this from giving her pain, that she assured me she could not feel that I was touching it at all. The eyelids made no effort to close, while I was doing this; but the conjunctiva appeared sen- sible to the stimulus, as a number of vessels on the surface of the eye became immediately in- jected with blood." Another circumstance may be advanced in fa- vour of the opinion that the nerve influences the nutrition of the parts, to which it is necessary to allude, viz. the wasting of the muscles of masti- cation in cases of the loss of the nerve's influence. This fact may be otherwise explained ; the de- velopment of muscles is always influenced by their exercise, which being lost they waste, and it is neutralized by the counter-fact that, though these masticatory muscles waste, the muscles of the face and its other structures do not. In fine there appears to the writer to be no good reason for attributing to the fifth nerve a direct influence upon the nutrition of the structures to which it is distributed; the existence of such an influence would be incompatible with the simplicity of natural laws, for in such case there must be two such influences in existence, one in the nerve directing the nutrition of the parts with which it is connected, and anothe elsewhere to direct that of the nerve. Magendie confirms his view of the influence exerted by the fifth nerve upon the functions and nutrition of the eye, by reference to a case published by Serres in the fifth volume of the Journal of Physiology, which " presented all the phenomena attending section of the fifth pair," and in which there existed complete alteration of the trunk of the nerve in its sen- sible portion ; " followed by loss of sight, of smell, of hearing, and of taste on the same side." Before detailing this case, the writer cannot refra:n from observing that in such cases none but unquestionable evidence can be admitted if we would arrive at a certain and unquestionable conclusion. Whether the case of Series be such, it rests with the reader to decide; and first, what was the condition of the patient in other respects ? Serres replies : " His air was dull; his physiognomy gave, at first sight, the idea of imbecility; he seemed to conceive slowly and to comprehend with difficulty, the questions which were put to him. When he wished to reply, it was evi- dent that he experienced difficulty in express- ing himself; he pronounced with difficulty, and the little that he said seemed to require, on his part, a considerable effort : his cranium was voluminous compared to the rest of his body ; some pupils suspecting a commencing hydrocephalus, thought that they observed a separation between the parietal and temporal bones, but the prominence of the eyes made me reject that conjecture ; the maxillary and malar bones were a little separated, which had produced a flattening of the nose ; the pa- tient had some difficulty in moving the tongue; the motions and sensibility of the limbs were not affected, only he moved the lower extre- mities less freely than the upper ; he had been for some time subject to epilepsy; he had a sister deaf and dumb." A case so complicated as this, in which there manifestly existed ex- tended disease of the encephalon, must be rejected as altogether inconclusive. But to proceed, the patient was admitted into hospital in September 1823: at his admission he had a chronic ophthalmia of his right eye, which was considered scrofulous. In the course of De- cember he was attacked by an acute ophthalmia of the same eye, attended by adema of the lids, and commencing opacity of the cornea; the ophthalmia was dispersed after ten or twelve days; but the cornea was rendered altogether opaque throughout its whole extent; of course the loss of vision on that side was the neces- sary result. In the course of January 1824 it was observed that the right eye was insensible, and soon after that the eyelid and nostril of the same side were also insensible, and likewise the tongue on that side, while all was natural on the other; soon after the gums inflamed upon the right; they were red, some white places existed here and there, they were swollen at the circumference of the sockets; the tongue moved always with difficulty; the hearing was not then affected; in July the affection of the gums extended to the left side, but the right 314 FIFTH PAIR OF NERVES. was always more affected than the left. During August the gums became separated on the right from the necks of the teeth ; there existed between the latter and the gums spaces into which tartar and portions of food had pene- trated ; the patient suffered from the epileptic paroxysms with variable degrees of severity : he next fell into a general cachexy, with extreme debility, impeded respiration, small frequent pulse, great alteration of countenance, and un- usual taciturnity. It is stated that in August he acknowledged deafness on the right, which diminished and again increased; the sensibility was perfectly preserved in all the extent of the right side of the face ; the patient died on the 12th of August. Both the brain and the fifth nerve were found after death much diseased, the brain on the left and the nerve on the right side. The details of the case have been given more at length than may perhaps seem necessary, but the question is interesting, and as the bearing of the case upon it could not be determined otherwise, the writer has endeavoured to give them faithfully. The difficulty of obtain- ing precise knowledge from so complicated a case has been already adverted to. We come next to inquire how far it substantiates the writer's views, or how far it can be considered to establish the opinion of Magendie. Serres, as has been already stated, announces it as an instance of disease of the fifth nerve followed by loss of smell, sight, hearing, &c. Surely the loss of these several functions, thus an- nounced, should have been satisfactorily esta- blished, before asserted ; but such does not appear to have been the case. For the first, notwithstanding the announcement, we find Serres himself, after the patient's death, ac- knowledging, " toutefois l'odorat n'avait pas completement disparu, puisque,"* &c. The sense of smell then plainly was not lost. In the next place there was loss of vision, but from what cause ? from opacity of the cornea, and, so far as we have data for forming a judgment, from it alone. We have no reason to think that any alteration had been pro- duced in the power of the eye to receive sensations of light, any disturbance in the function of the retina, or any other change than the occurrence of a physical impediment to the exercise of a function, which the organ may have retained in full vigour, had it only been allowed to exert it: the evidence, there- fore, afforded by the case, is too imperfect to be of value. Let us next inquire how far it bears out the opinion that the fifth nerve possesses a proper and direct influence upon the nutrition of the eye : here we shall find ourselves equally at fault for the resemblance which it has been sought to establish. In Magendie's experi- ments the section of the nerve preceded the occurrence of the phenomena, and it is reason- able to expect, that, here, the loss of sensibi- lity, which we are to regard as the analogue of the section, should have preceded the oc- 1 Journ. de Phys. t. v. p. 245. currence of the inflammation of the eye ; but no. The patient had a chronic ophthalmia, con- sidered scrofulous at the time of his admission; (he was admitted in September, and in De- cember he was attacked by acute ophthalmia, attended by oedema of the lids ; a circumstance not noticed in any of Magendie's experiments;) the inflammation was dispersed, and in the course of January, and not till then, (i. e. four months after his admission and about one after the occurrence of the second inflammation,) the insensibility of the eye was for the first time observed. Surely we have no reasonable grounds here for attributing the inflammation of the eye and the opacity of the cornea to the disease of the nerve, or for supposing that there existed any connexion, in the relation of cause and effect, between them. If we seek for a resemblance in other points, we shall be equally disappointed. It has been already remarked that oedema of the eyelids, which occurred in this case, is not one of the phenomena of Magendie's experiments. Again, the affection of the gums related is altogether unlike : in Serres' case they are stated to have become inflamed, and to have been affected on both sides, only more on the right than on the left; in Magendie's it is simply stated that they separated from the teeth and only on the side on which the nerve had been divided ; and, lastly, the continuance of sensibility upon the right side of the face throughout casts an im- pervious obscurity over the entire. Besides those effects of the section of the trunk of the nerve which have been discus- sed, there are others, for which we are in- debted also to Magendie, and which deserve notice. lie found after the section of the nerve that the eye was dry, and the motion of winking had ceased ; the globe of the eye itself seemed to have lost all its motions ; the iris was strongly contracted and immoveable. The loss of sensibility in the conjunctiva, and the sus- pension of the secretion of the tears, he refers to the loss of the influence of the fifth nerve upon the former part and upon the lachrymal gland : the explanation of the first is in accor- dance with the previously established proper- ties of the nerve as already ascertained by Mayo, but it is not equally so that the secretion of the lachrymal gland is directly controlled by the same influence, and it remains to be deter- mined whether the effect in this case was not an indirect one, consequent upon the previous insensibility of the conjunctiva. The other re- sults of the section — the immobility of the eyelids, that of the eye, and the permanent contraction of the pupil — he has not satisfac- torily explained : the immobility of the lids may, it appears to the author, be attributed with much probability to the insensibility of the conjunctiva or of the internal structures of the eye, and seems a likely consequence there- of : the ordinary action of winking would seem to be called into play through the sensations of those structures, and the cessation of that action upon the loss of their sensibility is as natural an effect as the immobility of the lips FIFTH PAIR OF NERVES. 315 on the contact of food consequent upon the division of the infra-orbital and inferior maxil- lary nerves : and this view derives confirmation from the circumstance that in the instance under consideration the immobility of the lids is not the consequence of paralysis, for on the sudden admission of solar light into the eye, the action of the muscle was excited, and the eyelids were closed. The immobility of the eye itself the author cannot but regard as an incidental circumstance, caused by the com- plication to which Magendie himself refers, viz. the division of the motor nerves of the eye along with the fifth, and this explanation is rendered more likely, if not confirmed, by the effect of the section when made between the ganglion and the brain, in which case the motor nerves are not involved, nor the motion of the eye affected. It is to be regretted that Magendie has not given a report of a dissec- tion after death of some of the animals upon which the former experiment had been per- formed, by which the question might have been determined. The permanent contraction of the iris is an extraordinary and as yet unex- plained effect : it occurred only when the experiment was made upon rabbits, and is at variance with the results of similar experi- ments upon other animals, performed both by Mayo and by Magendie himself. In Mayo's* experiments, which were done upon pigeons, in no instance was contraction of the pupil caused by division of the nerves connected with the eye or its appendages. When the optic nerve was divided, the pupil became fully dilated. When the third nerve was divided, the same result ensued ; and when the fifth was divided, the iris contracted as usual on the admission of light; in Magendie's experiments again upon cats and dogs the pupil was en- larged.f The fact is, however, confirmed by Mayo, who found that when the fifth nerve was compressed in a rabbit after death, the pupil became contracted slowly and gradually, and then slowly dilated ; and when the nerve was divided, the pupil became contracted to the utmost, and remained so. A correspond- ing difference between the conditions of the pupil after death in the subjects of experi- ment has been observed by Mayo, according to whom in the pigeon and cat it is naturally dilated, but in the rabbit, on the contrary, contracted.^: It has been already stated that Magendie divided the nerve within the cranium both after and before the occurrence of the ganglion : in the latter case — when the section is made between the ganglion and the brain — the re- sults are different in some remarkable respects from those attending the section in the former: the effect upon the senses is equally marked ; but the motions of the globe of the eye are preserved almost always, from which the author would infer that the loss of those motions in the former must have been caused by the divi- * Comment, part ii, p. 4, 5. t Journal, t. iv. p. 309. t Physiology. sion of the motor nerves along with the fifth, by the side of the cavernous sinus ; and also the changes which occur in the tissues of the eye are much less considerable ; the inflamma- tion and opacity ensue, but not to the same extent. Another very remarkable result of the sec- tion is displayed in the animal's mode of pro- gression as related by Magendie : " when the two nerves are cut upon an animal it seems blind, and its mode of progression is most sin- gular ; it advances only with the chin leant strongly upon the ground, pushing thus its head before it, and using it as a guide as the blind does his staff : the progression of an animal in this state differs altogether from that of an animal simply deprived of sight ; the latter guides itself easily by means of its whiskers, and by the sensibility of the skin of its face ; it stops at hollows, feels obstacles, and, in fine, it would be difficult to know whether it is blind or not; while the animal whose fifth nerves have been cut has but one mode of moving, and instead of avoiding obstacles, it persists often in pushing against them for several hours, so as finally to exco- riate the skin of the anterior part of the head."* This account, which is well calculated to excite at first extreme surprise, is after all strictly consistent, and illustrates strongly the importance of the nerves in question : in fact to the animal so circumstanced the head and face must be as a part which it does not possess, or rather of which it has been suddenly deprived, and which it yet believes itself to retain ; it can have no consciousness of their existence, while from habit, memory, and ignorance of the real condition of the parts, it yet believes them to be present, and to exercise all their usual func- tions. Thus the human being whose limb has been removed without any knowledge of what has actually occurred believes that he still pos- sesses it, acts as if he did, and is only con- vinced of his loss by the evidence of the senses of sight and touch. In like manner the ani- mal acts under the impression that it still possesses its ordinary faculties, and being altogether unconscious of the contact of ob- stacles in consequence of its loss of sensation in the part which encounters them, it acts as if it were not in contact with them, and endeavours still to advance, while it is unable to make use of sight, if this faculty be retained, as a a guide, because it has lost the correcting and regulating assistance of the sensation of its face as exercised through its whiskers ; and hence it does not appear to the author that the apparent blindness of the animal proves real blindness. Unassisted sight cannot teach us the distance of objects ; and the animal sud- denly deprived of the faculty of sensation may see the object, but not being made aware of its contact, must suppose that it has not reached it, inasmuch as the usual notice of its presence is not given by the sensibility of the face. Lastly, when the nerves have been divided * Journ. de Phys. t. iv. p. 181. 316 FCETUS. upon both sides, the lower jaw ceases to be supported by its muscles, and falls.* Influence of disease on the junctions of the nerve. — The inferences drawn from the anatomy of the nerve and from physiological experiment conjointly have been confirmed in a remarkable manner by the effect of disease of the nerve upon the functions of the parts to which it is distributed: several instances have been pub- lished exemplifying either partially or com- pletely that effect, when, whether from disease of the trunk of the nerve itself or from pressure upon it, its office has been interrupted, all the parts supplied by it are deprived altogether of both their tactile and ordinary sensibility : this loss of sensibility extends to the whole of the corresponding side of the head so far as the distribution of the nerve reaches to the fore- head, temple, ear, surface of the eye and its appendages, cheek, nostril externally and inter- nally, lower part of the face, lips, and mouth, the corresponding half of the tongue, of the palate, and the fauces ; upon all these parts the roughest contact produces no perceptible im- pression ; inflammation is not attended by pain, the most pungent or irritating effluvia do not affect the nostril or the conjunctiva, and the sense of taste is altogether lost in the aute- rior part of the same side of the tongue : at the same time the muscles of mastication — the ex- ternal ones at least — lose their contractile power, remain inactive during the process and waste, whence are produced a flattening and depres- sion in the site of the temporal and masseter, with prominence of the adjoining points of bone : however the special senses continue un- affected apparently, unless in so far as the sense of contact may be necessary to the perfect or ordinary fulfilment of their function, the olfac- tory function seems much impaired ; the pa- tient is insensible to the impression of ammo- nia, snuff, or other pungent agent, but still ac- knowledges a perception of odour. Vision continues throughout, and appears unaf- fected, unless from the supervention of in- flammation, by which the eye may be spoiled, or from the extension of the disease to the optic nerve or the brain : in the case before alluded to, which the author has witnessed, vision re- mained perfect for a considerable time ; amau- rotic symptoms supervened during the course of the disease ; but even after the occurrence of opacity of the cornea in consequence of in- flammation, the patient could still distinguish light. Hearing appears to have been affected in most, if not all the cases, in which the dis- ease had attained a considerable degree; it was so in the case seen by the author ; the sense of contact would seem associated with the perfect exercise of the sense. The facial muscles re- tain their contractile power; in the instance alluded to, though the temporal and masseter seemed quite paralyzed, the buccinator acted with energy as ascertained by holding the cheek between the finger and thumb during its con- tractions ; the slight want of adjustment, which may occur about the mouth, seems caused by * Magendie, Bell. the want of sensation in the lips. Lastly, in all such cases the eye of the affected side is liable to have inflammation excited in it by incidental causes ; for the most part this occurs at an advanced stage of the disease, and can be referred to some exciting cause ; it is attended by but little, if any pain, and opacity of the cornea is an usual result.* (For the Bibliography see Nerve.) (B. Alcock.) FOETUS, Gr. wnpa. ; Ft, foetus; Germ. die Frucht ; (normal anatomy). See Ovum. FOETUS (abnormal anatomy). Considering the peculiar circumstances of the foetus in utero, we would, at first sight, be inclined to suppose that, although of course exposed to the risk of injury from accidents or diseases occurring to the mother, it would not be liable to many or serious accidents of its own ; nevertheless, ob- servation and experience soon reveal to us a very different state of facts, and force upon us the sad truth that the seeds of life are often sown adulterated with those of infirmity and decay, that disease may mutilate, and death destroy, even before our entrance into life ; for as far as investigation has enabled us to reach, we have reason to believe that the child before birth is not only liable to certain affections which may be considered peculiarly its own, but is also subject to almost all those which affect the adult. Of these affections some appear to be, 1. strictly innate in the constitution of the foetus; 2. some communicated by infection from the mother's system ; 3. some from the father's sys- tem, or perhaps through that of the mother, she herself not being the subject of the affection entailed, as in certain forms of syphilis, scrofula, and small-pox ; 4. some, from strong mental impressions on the mother; 5. some, arising from morbid alterations in the envelopes of the ovum, the placenta, and cord, or in the uterus itself; 6. some, from the influence of external agents, as falls, blows, pressure, &c. The investigation of these abnormal con- ditions is invested with a deep interest, not only as an important pathological inquiry, but as conducive to the adoption of mea- sures calculated to be beneficial to both mo- ther and child ; to the child, by suggesting the strong necessity for preventing the exposure of the mother to influences likely to affect the welfare of her unborn offspring, as well as for removing their effects by proper remedial means : and to the mother, by affording us occasionally information of the existence of diseased taints in her system, of which we might otherwise long remain ignorant ; or by guarding her against the ill effects of unhealthy states of the child ; for, although each indivi- dual has a separate existence, there is at the * Mayo, Commentaries and Physiology ; Bell, Philosoph. Transactions and on Nerves, 1830 ; Serres, Journal de Physiologic, t. viii ; Noble, Medical Gazette ; Bishop, Medical Gazette, vol. xvii. FCETUS. same time a very close and intimate mutual dependence of the one on the other; and, con- trary to what we would at first expect, the health of the mother is more apt to suffer from morbid conditions of the foetus in utero than is the latter to be injured in its developement by the state of the mother's system. Thus we see how great a disturbance is often caused in the maternal system by a blighted ovum, or a dead and putrid foetus ; while, on the other hand, we frequently observe that women in states of the most infirm health,* both mental and bo- dily, nay even when sinking under the ravages of some wasting disease, or depressed and worn out by mental suffering, by want of food or ex- cessive fatigue, give birth to full-grown and well-thriven children. The affections to which the foetus is liable vary not a little according to the period of its existence at which we consider it ; during the earlier periods, when the formative process is in most active operation, and the developement of the different organs is proceeding rapidly, many important and remarkable organic altera- tions take place ; some from arrest of develop- ment caused by imperfection in or morbid alteration of the structures of the ovum ; some by destruction of parts already formed, by atrophy or inflammation, or both conjoined ; some by the effects of excessive secretion and the consequent unnatural distension, &c; while those affections, to which more strictly belong the name of diseases, affect the more matured foetus, whose organization approaches more closely that of the new-born child. In order to give a full account of the morbid and abnormal conditions of the foetus, we should embrace also those of its appendages or surrounding structures of the ovum ; these, however, will be alluded to at present only so far as is absolutely unavoidable, as they will receive full consideration in the articles Ovum and Placenta : and in like manner several varieties of malformation will be with more propriety described under the head of Mon- strosity, while others will be found under the account of the different organs concerned. The germ, even before its vivification in the ovary, may have a morbid taint communicated to it from the system of the female in whom it resides, or from that of the man with whom she cohabits, so that the tendency to disease or malformation sometimes precedes the first im- pulse that leads to the establishment of life. Another source of abnormal conditions in the foetus occurs in the cohesion or intus-susception of germs, in consequence of more than one ovulum being contained within the same vesi- cle ; under which circumstances unnatural union may take place between two foetuses, and give rise to the production of such anoma- lies in organization as the Siamese twins, or to other forms of foetal duplicity, more or less re- sembling the remarkable instance represented in the annexed sketch of two children born a * See several instances recorded by Mauriceau, Malad. Extension performed .by rl. Downwards and in wards accomplished by ." The motions between the first and second row ofW tarsal bones* are . . . U s , by 1. Flexion performed by 4. 5. 2. Extension by The motions of the toes are-< 3. Abduction by 4. Adduction by In this table we are struck with the propor- tion which the antagonist muscles bear to each other, both in numbers and in individual as well as collective power. This proportion is of course regulated by the demand for muscular force in the ordinary movements of the joints. The extension of the ankle, in the most ordi- nary mode of its performance, implies the lift- ing of the whole weight of the body by the elevation of the heel, the toes resting upon the ground. This, owing to the unequal length of the two levers, requires an immense power, while the shortness of the moveable lever allows of very little extent of motion. The gastro- * It is remarkable that so original and accurate an observer as Dr. Barclay should attribute this motion to the ankle-joint, and sliould deny any motion, more than a mere yielding, to any of the tarsal bones. But it is still more surprising that he should make the same observation of the carpus, when so very considerable a part of the ordinary motion at the wrist is obviously between the two rows of carpal bones. See Barclay on Muscular Motion, pp. 404, 447. Tibialis anticus. Peroneus tertius. Extensor longus digitorum. Extensor proprius pcfflrcis. Gastrocnemius externus. Gastrocnemius internus. Plantaris. Flexor longus digitorum. Flexor longus pollicis. Tibialis posticus. Peroneus longus. Peroneus brevis. Tibialis posticus. Extensor proprius pollicis. Flexor longus digitorum. Flexor longus pollicis. Peroneus Longus. Peroneus brevis. Peroneus tertius. Extensor longus digitorum. Flexor longus pollicis. Flexor brevis pollicis. Flexor longus digitorum. Flexor brevis digitorum. Flexor accessorius digitorum. Lumbricales. Flexor brevis minimi digiti. Extensor proprius pollicis. Extensor longus digitorum. Extensor brevis digitorum. Abductor pollicis. Abductor minimi digiti. f Pri< I Prk (_ Prior tertii digiti. . Adductor pollicis. . Transversalis. {Prior minimi digiti. Posterior indicis. Posterior meda digiti. . Posterior tertii digiti. cnetnii are accordingly thick short muscles, with a long and powerful tendon. These are assisted by the plantaris and five other muscles. Flexion, on the contrary, which generally im- plies merely the elevation of the foot, without any other force to overcome, is adequately provided for by only four muscles, and these not large, indeed one of them very small. The assistance rendered by the five auxiliary muscles, which pass behind the malleoli, though considerable on the whole, yet is small individually in proportion to their size, owing to the disadvantageous situation which their tendons occupy at so very short a distance from the centre of motion ; for this reason, — when the tendo Achillis is ruptured, the patient is as incapable of walking as if all the extensor muscles were divided, yet when the body is resting the antagonism of the extensors is not entirely lost. The foot is not permanently bent upwards, and the simple act of extension can be accomplished without great difficulty. One of the most remarkable of all the extensor muscles, both as to its course and its function, rior indicis. InterosseH Prior medii digiti. 360 MUSCLES OF THE FOOT. is the peroneous externus. (See Leg, Mus- cles of.) The tendon of this muscle passes behind the outer malleolus, then, running downwards and forwards, it enters a groove formed in the os calcis, close behind the pro- minence of the base of the fifth metatarsal bone. It then runs across the sole of the foot, in contact with the bones, to be fixed to the inner cuneiform bone and metatarsal bone of the great toe. The course and situation of the tendon well deserve particular attention in the dissection of the foot. Without some study, it is impossible fully to understand its office, or how essential its action is to the mechanism of progression. If we examine the general form of the foot, we see that the anterior end of it is not square, owing to the comparative length of the toes. These are not of equal length, but are each shorter than the other as we proceed outwards, the outermost of all being the short- est. This part of the foot then is like the end of an oblong, with one angle greatly rounded off. When, therefore, the weight of the body is, by the elevation of the heel, thrown forwards upon the toes, there is necessarily a tendency, in this shape of the foot, to tilt the pressing force out- wards, whereas if all the toes had been of equal length, the elevation of the heel would simply have thrown the weight directly forwards, the support being equal on both sides of the foot. This tendency outwards, occasioned by the difference in length of the toes, is still further increased by the difference in strength, the largest, the most unyielding support, being on the inner side of the foot, the smallest and the most yielding being on the outer. This then being the construction of the basis of support, some means of counteracting this tendency was necessary to enable us to carry the body directly forwards, even in the simple act of walking, and still more in the more violent exertions. This is accomplished by the peroneus longus, whose tendon, like a girt, passes under the outer edge of the sole, and thus, lifting this, and in some degree turning the sole outwards, throws the weight of the body upon the great toe. This action of the muscle is particularly exemplified in the movements of skaiting. The movements of the bones of the tarsus are so distinct and constant that we have clas- sified the muscles which act upon them sepa- rately from those of the ankle. (See Foot, Joints of.) The muscles of the great toe are remarkable, as might be expected, for their size and strength. The long flexor is considerably larger than that common to the other toes, and gives to this a slip of its tendon, so that the flexor longus pol- licis does in fact assist in flexing all the toes. The general arrangement of all the muscles and tendons in the sole is very curious, and has a further object than the mere flexion of the toes. The great toe is, as we see, well provided, and it needs this, since it bears the greatest share of the burden of the body in walking, &c. The muscular provision for the other toes is as considerable, and indeed more so, in pro- portion to the size of the toes. There is, 1st, the flexor brevis digitorum ; 2d, the flexor longus Fig. 169. 1 Flexor accessorius. 2 Flexor pollicis longus. 3 Flexor digitorum longus. 4 Slip from the flexor pollicis longus to the flexor digitorum longus. 5 Lumbricales. 6 Tendon of long flexor. digitorum ; 3d, this tendon receives an aux- iliary tendon from the long flexor of the great toe; 4th,themassacarnea; 5th, the lumbricales. There can be little doubt that the use of all these muscles is to give a powerful support to the antero-posterior arch of the foot, to which purpose the mere ligaments would be little equal. But we must admire not only the number and force but the arrangement of these muscles, which are so placed as to act, almost all of them, from the same centre, and there- fore with greater advantage for the object of strengthening the arch. Thus the flexor brevis digitorum lies pretty nearly central in this region, while immediately under it the flexor longus digitorum, running from within outwards, is crossed in the opposite oblique direction by the flexor longus pollicis, and these again are still further checked outwards by the flexor accesso- rius, so that the centre of action of all these mus- cles and of the lumbricales also, which arise from the long flexor tendon, is in the same line as the flexor brevis, which lies over them, and as a support to the great arch of the foot this arrange- ment of the muscular chords must have a pecu- liarly advantageous effect. (A. T. S. Dodd.) For the Bibliography, see Anatomy (Intro- duction). FORE-ARM. 361 FORE-ARM, (Surgical anatomy), (Anti- brachium ; Fr. Avant-brus; Germ, der V order- arm )■ This term is applied to that portion of the upper extremity which is situated be- tween the elbow and wrist-joint. In the well-formed male all the muscles of this region, but especially the supinators, from the fascia which covers them being extremely thin, when thrown into action stand out in strong relief, giving an appearance of great power concentrated within a small space. In the female, on the contrary, the fore-arm, from the great preponderance of adipose tissue, presents a swelling outline and rounded form, not the less beautiful, perhaps, from indicating deficiency of muscular energy, and conveying the idea of softness and dependence. The usual and least constrained position of the fore-arm is with the hand between prona- tion and supination, that is, with the palm of the hand inwards and the dorsum outwards; but for the purpose of anatomical description the palm of the hand is supposed to face for- wards and the dorsum backwards, the fore-arm being extended. In this position the fore- arm obviously differs from the arm in being wider from side to side than from before back- wards. Superiorly it presents in front a very slightly convex surface, but inferiorly there is formed by the flexor tendon a distinct central projection, which is bounded by the flexor carpi radialis on the radial side, and by the flexor carpi ulnaris on the ulnar. The posterior surface of the fore-arm is more irregularly convex than the anterior; the greatest convexity is nearer the ulnar than the radial edge, and is formed by the olecranon above and the shaft of the ulna below, which is covered only by the skin superiorly. A con- siderable depression may be observed, bounded on the inner side by the olecranon, and on the outer by the supinators ; in this depression the outer condyle may be felt. To the inner side of the olecranon there is a corresponding but much smaller depression, in which the inner condyle is situated. For about three inches above the wrist-joint the fore-arm pos- teriorly is slightly concave in the centre in consequence of the marked projection of the ulna and radius on either side. In the motions of pronation and supination the shape of the fore-arm is considerably changed ; but as no practical advantage can attend a detailed ac- count of the changes undergone, we shall not dwell upon them here. The parts composing the fore-arm are as fol- low : the radius and ulna, the muscles of the hand and fingers, the radial and ulnar arteries with their branches, the venae satellites of these arteries and the subcutaneous veins, the radial, ulnar, median, and cutaneous nerves, the ab- sorbent vessels, a quantity of cellular and adipose tissue, various aponeuroses, and the common integuments. The configuration, relative position, and connection of the bones of the fore-arm have been described in the article Extremity. They move together in the flexion and exten- sion of the fore-arm on the os humeri at the elbow-joint, under the influence of the biceps flexor cubiti and brachialis anticus, and the triceps extensor cubiti and anconeus. In the motions of supination and pronation the radius is always rolled upon the ulna, the latter remaining perfectly fixed, though this fact has been disputed in consequence of the thick sacciform ligament of the wrist and the tendon of the extensor carpi ulnaris being felt to roll under the finger when placed on the inferior extremity of the ulna during the motion of rotation and supination, and thus communicating the sensation of a motion in the ulna itself. The skin of the fore-arm differs considerably on the dorsal and anterior aspects. On the former it is coarse and comparatively rough, containing numerous small hairs ; on the latter it is smooth and more delicate, and the adipose tissue being more abundant on the anterior, the whole surface is more even, while on the posterior the extensor muscles of the hand and fingers, being slightly covered, project considerably. Neither of the regions, however, contain so much fat as most other parts of the body. The superficial veins which are subject to the greatest variety, are usually more distinct and numerous on the dorsal aspect, particularly at the lower part. The subcutaneous nerves, which are very numerous, are derived from the following sources : 1st, the internal cutaneous nerve, which is one of the divisions of the axillary plexus; 2dly, the cutaneous branch of the radial ; 3dly, the musculo-cutaneous. The internal cutaneous nerve divides into two branches in the upper arm, in which region it accompanies the basilic vein. These two branches penetrate the fascia separately above the elbow-joint, and the one, the an- terior branch, descends on the front of the fore-arm, the other, the posterior, on the back of it. The anterior branch usually passes behind the basilic vein, sending a small twig or two anterior to it. Its course is continued to the wrist-joint, supplying the skin on the anterior and inner side throughout ; the pos- terior division accompanies the basilic vein, and may be always traced to the back part of the wrist. The small branches of this nerve, which cross in front of the basilic or median basilic vein, are occasionally wounded in the opera- tion of venesection ; an accident which gene- rally excites considerable inflammation, with severe constitutional irritation, symptoms which are sometimes erroneously attributed to the action of a foul lancet. The skin on the anterior surface of the outer half of the fore-arm is supplied with nerves by the external cutaneous nerve, a division of the axillary plexus : it is a deep-seated mus- cular nerve in the upper arm and penetrates the fascia, becoming subcutaneous anterior and a little below the elbow-joint. In this situation it is posterior to the median cephalic 362 FORE-ARM. vein ; its branches are numerous throughout its course, which terminates at the wrist-joint in the supply of branches to the skin on the dorsum and ball of the thumb, which inosculate with the cutaneous of the radial. This last-mentioned branch, the cutaneous of the radial, is derived from its trunk on the outer side of the middle of the arm ; imme- diately after that nerve has emerged from between the triceps extensor and the bone, a series of branches is distributed to the skin of the arm. The remainder of the nerve, which is a descending branch of some size, passes down behind the elbow-joint, and be- coming subcutaneous supplies the skin of the posterior surface of the outer half of the fore- arm, and corresponds to the musculo-cutaneous on the anterior. Thus it will be seen that the skin on the inner side of the fore-arm, both anteriorly and posteriorly, is supplied by the internal cutaneous, while that on the outer side is supplied in front by the musculo-cu- taneous, and behind by the radial nerve. The superficial veins of the fore-arm, though subject to the greatest variety, are usually distinguished by the names of the cephalic, basilic, and median. The two first commence on the back of the hand ; the cephalic on the external, and the basilic on the internal side. They freely anastomose at the lower part of the fore-arm, after which they separate, and reaching the anterior surface below the elbow, are joined by the median vein, as described in the article Elbow. The superficial absorbents take nearly the same course as the veins, though they are far more numerous, and on the whole pursue a straighter direction. The course of these vessels is occasionally demonstrated in the living subject by active inflammation of their coats following the absorption of irritating matter. Aponeurosis. — The aponeurosis of the fore- arm is simply a continuation of the same structure, which surrounds and supports the muscles of the upper arm ; it varies very much in density and appearance in different situa- tions ; this difference arises from the fact that both the triceps extensor and biceps flexor cubiti send to it many fibres, which not merely give additional strength to its texture, but also act as a medium through which these muscles possess the power of making tense the fascia. This provision for tightening and supporting the fascia of the fore-arm is analogous to those arrangements which we meet with in the thigh and leg. The fascia of the fore-arm is strongest at the posterior part of the limb, on each side of the olecranon. The fibres derived from the tendon of the triceps on the external side pass trans- versely outwards to be inserted into the outer condyle, intermingling with the radial exten- sors at their origin, at the same time firmly connected to the olecranon process, posteriorand internal edge of the ulna, thus forming a dense and firm covering to the anconeus, between which muscle and the extensor carpi ulnaris a process of fascia is met with which forms a dense septum between the two. The fibres from the internal edge of the triceps at the upper part also pass transversely, reaching the inner condyle, intermingle with the origin of the flexor muscles ; others again, descending at the back part of the arm, form an aponeurosis over the flexor carpi ulnaris; while those which pass forwards intermingle with the aponeurotic fibres of the biceps. These fibres from the biceps are uniformly strong and distinct, and give a great firmness and density to the fascia on the inner side of the arm covering the flexor muscles, which is not met with on the outer side of the arm supporting the supinators. The fascia in front of the fore-arm which covers the supinators receives its last fibrous connexion from the tendon of the deltoid. The fascia of the fore-arm on reaching the posterior part of the wrist-joint has interwoven with its texture many beautifully distinct fibres, taking a slightly oblique course from without to within, and from above to below ; these fibres, which are firmly attached to the radius on the outer side and the ulna on the inner, become insen- sibly lost in the fascia on the back part of the hand, which resembles in its homogeneous appearance the fascia on the lower part of the fore-arm ; these supplementary fibres to the fascia, though presenting a distinct edge neither above nor below, act as a ligament to the exten- sor tendons in their passage behind the wrist- joint, which has been called by some anatomists the posterior annular ligament ; between these tendons and the ligament there is a large and distinct bursa, not unfrequently the seat of inflammation. The fascia on the lower and fore part of the fore-arm, consisting principally of transverse fibres, becomes gradually thinner, and in front of the wrist-joint is inseparably in- terwoven with the fibres of the annular ligament. The aponeurosis of the fore-arm forms many septa between the muscles. Commencing with the description of the septa in the back part of the arm, we find a dense and strong one sepa- rating the anconeus from the extensor carpi ulnaris, and from which the latter muscle takes part of its origin. A second dips between the extensor carpi ulnaris and extensor communis digitorum, giving origin to both. A third is found between the common extensors of the fin- gers and radial extensors. The radial extensors and supinators are not thus separated from each other. A fourth process, distinct though com- paratively thin, separates the supinator radii longus from the brachialis anticus, the tendon of the biceps, pronator radii teres, and flexor carpi radialis. There is also another process which unites the tendon of the supinator radii longus on the outer side to the flexor carpi ulnaris on the inner side, and forms a firm and dense covering to the radial artery. The pro- nator radii teres is scarcely separated from the flexor carpi radialis by a distinct septum, though the last-mentioned muscle is completely separated from the palmaris longui by a dipping in of the fascia. Between the flexor communis digitorum sublimis and flexor carpi ulnaris there is a very perfect and distinct septum. FORE- ARM. 363 Of the different morbid growths which arise in the cellular tissue of the fore-arm, those ■which are superficial and those which are beneath the fascia require careful distinction, the removal of the former being easily effected, while all operations on the latter require great consideration and care. The superficial tumour projects under the skin, creating some deformity ; it may be moved with facility, for its attachments are loose ; while, on the other hand, the deep- seated or sub-fascial tumour has frequently a flat- tened surface, and often appears, on superficial examination, insignificant and of small extent, while in fact its mass is considerable, bur- rowing deeply between the muscles. It is to be distinguished from the supra-fascial tumour by its comparative immobility, by the various effects produced upon it by the fascia when in a state of tension or relaxation, by the pain produced by pressure on nerves, or impediment to the circulation from pressure on the vessels. In the removal of the sub-fascial tumour the operator must call to mind the direction and relative position of the muscles in the neigh- bourhood of it, as the roots or under surface of these generally follow the interspace between the muscles, and are thus guided to a great depth among the vessels and nerves of the fore-arm. The same principles apply to the diagnosis and treatment of superficial and deep-sealed abscesses. The superficial abscess is less cir- cumscribed ; the matter is diffused without limit through the subcutaneous tissue ; from its position the absorption of the superincum- bent tissues takes place rapidly, the skin either giving way entirely without the aid of the surgeon, or else pointing at some particular spot indicates where the abscess lancet may be employed with advantage. The sub-fascial abscess, on the contrary, pro- ceeds slowly in many cases, and even insidiously, bound down by the unyielding fascia ; it tells us of its presence, in the first instance, rather by the constitutional disturbance which it rouses than any striking indications of local mischief. These abscesses are occasionally the consequence of inflammation commencing in the theca of the flexor tendons, and the bur- rowing of the matter upwards in the course of the tendons. The septa of the fascia, which have been described passing down between the muscles to the bone, limit the passage of the pus in different directions. The fascia itself is not much subject to disease, though it seems peculiarly disposed to slough as a consequence of phlegmonous ery- sipelas. Vessels. — The main arteries of the fore-arm are the radial and ulnar, into which the brachial artery divides just below the bend of the elbow. The brachial artery at this spot has on its outer side the tendon of the biceps ; on its inner side, one of the venae comites, the median nerve, and the pronator radii teres muscle. Behind the brachial artery is the brachialis anticus muscle, and in front of it the fascial insertion of the biceps muscle. The radial artery, which is the smaller of the two divisions, pursues nearly the same direction as the brachial, and in the lower part of the upper third of the fore-arm is found exactly midway between the radial and ulnar surfaces, overlapped by the supinator radii longus, and lying upon the tendon of the pronator radii teres muscle, with the radial nerve about a quarter of an inch to its outer side, and separated by fat and cellular mem- brane. From this point the radial artery descends towards the wrist-joint, and at the lower part of the upper half of the fore-arm quits the pronator radii teres, and passes on to the anterior surface of the flexor longus pollicis, having the flexor carpi radialis to its inner side. A little lower down, that is, at the upper part of the lower third, the vessel emerges from beneath the supinator radii longus muscle, and is covered only by the fascia. In its further course to the wrist-joint the flexor carpi radialis maintains its position on the inner side, to which the tendon of the supinator radii longus corresponds on the outer. The radial nerve no longer accompanies the vessel, for it has now slid under the supinator radii longus, and reached the posterior face of the arm. As the radial artery just above the wrist-joint is covered only by the fascia, and lies upon the bone, its pulsations are easily felt, and in con- sequence of its convenient situation is generally selected by the medical practitioner to ascertain the general state of the circulation. We should, however, always bear in mind the great variety both in size and distribution to which this vessel is liable, and take the precaution of at least examining the radial artery in both arms. The inner edge of the supinator radii muscle is a certain guide to the situation of this artery should the surgeon be required to secure it, and this should always be effected by two ligatures, as its free anastomosis below will certainly produce secondary hemorrhage if this precaution is neglected. As the nerve lies on the outer side of the artery, the needle must be passed from without inwards. The ulnar artery has a deep course, first passing beneath the median nerve, which se- parates it from the pronator radii teres muscle, next beneath the flexor digitorum sublimis, the two last muscles separating it from the flexor carpi radialis and palmaris longus, and upon the flexor digitorum profundus, and when it reaches the tendon of this muscle midway between the wrist and elbow-joints, it comes into contact with the ulnar nerve, by which it is separated from the flexor carpi ulnaris muscle on its inner side. In its further descent to the wrist-joint it is situated between the flexor communis digitorum sublimis and flexor carpi ulnaris. Gradually sliding behind, the tendon of the latter remains covered by it for about two inches above the annular liga- ment of the wrist, in front of which it passes into the palm of the hand. The third branch worthy of mention in this division of the fore- arm is the anterior interosseal. This vessel 364 FORE-ARM. is a branch of the ulnar artery, and not unfre- quently is of large size, though usually of a calibre about intermediate to the two last men- tioned. It arises from the ulnar artery where that vessel is covered by the pronator radii teres, and descending towards the interosseal ligament reaches that structure a little below the tendon of the biceps. It is accompanied by a branch of the median nerve in its course downwards ; lies between the interosseous liga- ments and the external edge of the flexor com- munis digitorum profundus ; it terminates by dividing into two branches, of which one passes backwards through the interosseal liga- ment, anastomosing with the posterior inter- osseal, and the other, a small branch , descends over the wrist-joint into the palm of the hand, where it anastomoses with the deep palmar arch. In the posterior region of the fore-arm we meet with only one vessel of any size ; this is the posterior interosseal artery, a branch from the anterior interosseal, which passes through the interosseal ligament opposite the tubercle of the radius; its course is not so straight and uniform as the anterior, its distri- buent branches are larger and more numerous, and it may be said to ramble down between the extensor muscles and the interosseal liga- ment, though it does not lie so immediately in contact with the ligament as the anterior inter- osseal. It terminates by anastomosis with the vessels about the wrist-joint. Such is the usual distribution of these ves- sels ; they are, nevertheless, subject to every kind of variety, and theoperator previously to the commencement of an operation ought always carefully to examine the course of these vessels in order to detect any anormal arrangement either in relation to their size or distribution. The arteries of the fore-arm are more ex- posed to accidents from cutting instruments than most other vessels in the body ; and the usual plan of securing the vessel in these cases is to apply two ligatures on the wounded trunk, one above and the other below the orifice, the latter being required in consequence of the free anastomosis of the vessels in the hand. But the fore-arm is occasionally wounded by sharp penetrating instruments, which passing deeply into the fleshy mass, the vessel which has been wounded is not immediately indicated, and the surgeon is consequently at a loss to discover which of the three main trunks requires the application of a ligature. An examination through the wound would tend to aggravate the mischief, and besides, the search is often attended with difficulty, and often unsatisfactory. In such cases it will be found far more advantageous to arrest the hemorrhage by pres- sure on the brachial artery, at the same time allaying the local inflammation by due attention to the position of the arm, and the usual antiphlogistic remedies, a plan which I have seen adopted with great success by Mr. Tyrrell, at St. Thomas's Hospital.* * See St. Thomas's Hospital Reports, edited by John F. South, No. i. p. 25. There are some cases, however, which im- peratively require the application of ligatures, as for instance, when either of these vessels is opened by sloughing of the tissues from phleg- monous inflammation, or from aneurism in the fore-arm or hand. In the first of these cases, patients have frequently been lost from the temporary suspension of the hemorrhage by the use of cold applications or accidental circumstance, and its occurring again suddenly during the absence of the surgeon. In the performance of the operation of tying the radial artery the supinator radii longus muscle affords an unerring guide throughout the fore-arm, but the surgeon must remember that the inner edge of this muscle is not on the outer side of the fore-arm, but as nearly in the centre as possible. The needle must be passed from without inwards, in order to avoid wound- ing the nerve. The ulnar artery cannot be secured in the upper third of the arm, it lies so completely covered by most of the flexors arising from the inner condyle ; as soon as the vessel has gained its position between the flexor carpi ulnaris and the flexor digitorum communis, it may be easily reached, the former muscle overlapping it, and therefore forming an excellent guide. The needle in this operation must be passed from within outwards, as the nerve lies to the ulnar side of the artery. The bones of the fore-arm are not unfre- quently fractured, either singly or together, but the radius, from its external position and strong connection with the bones of the hand, is more frequently fractured than the ulna. The injury generally takes place a little above the middle of the bone. When both bones are fractured, the accident is frequently occasioned by the passage of a heavy weight over the limb, the violence acting immediately on the injured portions. Jn child- hood these bones are sometimes bent instead of being broken, and as the deformity is slight, though the effect altogether very serious, the nature of the accident is not very readily de- tected. " When these bones are fractured near their inferior extremities," says M. Boyer,* " the in- flammatory swelling might render the diagnosis difficult, and cause the fracture to be mistaken for a luxation of the hand. But the two cases may be distinguished by simply moving the hand ; by the motion, if there be luxation with- out fracture, the styloid processes of the radius and ulna will not change their situation ; but if a fracture do exist, these processes will follow the motion of the hand." If the radius be fractured a little below the head and above the tubercle, that is, through the neck, and the annular ligament remain en- tire, the deformity is so slight that there is great difficulty in detecting the nature of the injury, especially if there be much swelling and effu- * Lectures of Boyer upon Diseases of the Bones, arranged by M. Richerand, translated by M. Far- rell, vol. i. p. 161. MUSCLES OF THE FORE-ARM. 365 sion. Unless the surgeon can distinctly feel the head of the radius, so that he can clearly ascertain on rotating the lower portion with the hand, that the upper does follow but remains perfectly unmoved, he has no equivocal guide as to the real nature of the injury. If the ulna is fractured separately from the radius, which seldom occurs, the injury gene- rally happens to the lower third of the bone, which is much smaller and more exposed than the upper ; the accident is easily detected by running the finger down the posterior edge of the bone. When the radius is fractured near its centre, the pronator quadratus muscle ob- tains entire power over the bone, and drawing the lower portion across towards the ulna, causes a considerable projection in the anterior interosseous space. If this be not corrected by the use of a pad, as recommended a little fur- ther on, the two bones will unite, and all mo- tion of pronation and supination be entirely lost. In all these cases of fracture of the bones of the fore-arm, nearly the same plan of treatment is required, namely, 1st, two pads, increasing in thickness from the elbow to the wrist, and not wider in any place than the arm itself, suffi- ciently soft to be pushed well into the interos- seal spaces, applied anteriorly and posteriorly ; a long linen roller enveloping the hand and the whole of the fore-arm, and pressing the pads between the two bones, so as to counteract the action of the two pronator muscles which have a tendency to bring them together. Splints ex- tending from the elbow to the hand. When the radius alone is fractured, it is ad- visable not to support the hand, but to allow it to hang down, and by this plan the hand acting as a weight, will draw the lower fractured por- tion, which has a tendency to overlap the upper, downwards, and thus bring them into apposition. (Samuel Solly.) FORE-ARM, MUSCLES OF THE.— When we consider how varied and complex are the motions of the arm and hand, it is no matter of surprize that so many as nineteen muscles should be found composing the fleshy mass of the fore-arm. These muscles may be classified in reference to their action, and are briefly enumerated as follows: — In the first place there is one muscle physio- logically belonging to the upper arm, the anco- neus ; the rest are connected with the hand ; for instance, there are three flexors of the hand ; flexor carpi radialis, flexor carpi ulnaris, pal- maris longus. Three extensors of the hand, extensor carpi radialis longior, extensor carpi radialis brevior, extensor carpi ulnaris. Three long flexors of the thumb and fingers ; flexor communis digitorum sublimis, flexor communis digitorum -profundus, flexor longus proprius pollicis. Five extensors of the thumb and fingers, extensor ossis metacarpi pollicis, exten- sor primi internodii, extensor secundi internodii, extensor communis digitorum, extensor indicis. Two supinators, supinator radii longus, supina- tor radii brevis. Two pronators, pronator ra- dii teres, pronator quadratus. In proceeding to describe the attachments and relations of the foregoing muscles, it will be found convenient to examine them as they are met with in the following regions of the fore-arm. 1. The anterior region, which con- tains a superficial and a deep set of muscles. 2. The posterior region, which likewise has its superficial and its deep layers of muscles. These regions again may be conveniently sub- divided into radial and ulnar sections, between which a very natural line of demarcation is observable after the skin and adipose tissue have been removed. Exactly on this line, and one-thiid from the elbow and two-thirds from the wrist-joint, two long muscles will be found in contact, the supi- nator radii longus in the radial section, the flexor carpi radialis in the ulnar. Above and below this point these muscles diverge. The flexor carpi radialis, at its origin from the inter- nal condyle, is distant, from the boundary line referred to, at least one-third of the transverse diameter of the arm, and the space thus left, triangular in its figure, contains a large portion of the pronator radii teres. The radial edge of the pronator radii teres is in contact with the supinator radii longus to the extent of about an inch and a half; this muscle descending in like manner obliquely from its origin in the ulnar section towards the radial leaves above a similar though small triangular space, in which the tendon of the biceps flexor cubiti is lodged. Below the point referred to above, between the elbow and wrist, the flexor carpi radialis runs in contact with and on the ulnar side of the boundary line till within an inch and a half of the wrist-joint, where it gradually slides into the radial section, so that at the annular liga- ment the tendon of the flexor carpi radialis will be found entirely in the radial region with its internal edge in contact with the boundary line. Thus it will be seen that a line drawn from the elbow to the wrist and dividing the fore- arm into two portions, of which the internal or ulnar section is exactly two-thirds, while the external or radial section is only one-third of the transverse width, not merely forms an arti- ficial division into radial and ulnar sections, but also points out the exact situation of the tendon of the biceps, the outer edge of the pronator radii teres, and the flexor carpi radi- alis, and in addition, as we shall presently see, the supinator radii longus. The fleshy belly of this muscle lies exactly parallel with this boundary line in the upper half of the arm. In consequence of the supinator radii longus becoming tendinous about the middle of the fore-arm, and the tendon being narrower in its transverse diameter than the muscle, a space is left at the lower part of the arm between it and the flexor carpi radialis, and the supinator radii longus is no longer met in contact with the boundary line. In this space is lodged the radial artery, lying midway between these two 366 MUSCLES OF THE FORE-ARM. tendons, separated "from the flexor longus pol- licis by a deep layer of fascia, which is united to the edge of the supinator radii longus on the outer side, and the flexor carpi ulnaris on the inner side Muscles in the anterior region of the fore-arm. — a. Superficial layer of muscles. — On the radial side we observe two, supinator radii longus and extensor carpi radialis lon- gior. 1. Supinator radii longus, (grand supina- teur, Cloq., brachio-radialis, Soemm.,) arises by a broad, flat, fleshy origin from the rough ridge, on the outer side of the lower extremity of the os humeri, which gradually terminates in the outer condyle; it is connected at the apex of its origin with the deltoid : it arises likewise from the intermuscular ligaments of the upper arm ; passing over the elbow-joint, its surfaces, which in the upper arm face outwards and in- wards, are converted into anterior and posterior in the fore-arm ; opposite the tubercle of the radius it becomes tendinous on its under sur- face, and the fleshy fibres on its anterior face entirely disappear about the middle of the fore- arm in a flat tendon, which, narrowing as it descends, is inserted into the external edge of the base of the radius. This muscle at its origin has to the inner side of it the brachialis anticus muscle and the radial nerve and superior profunda artery; to its outer side and posteriorly the triceps ex- tensor cubiti; a little lower down and just above the elbow-joint it has the extensor carpi radialis longior to its outer side, which maintains a uniform relation to it in its whole course ; in passing over the elbow-joint the tendon of the biceps flexor cubiti separates it from the bra- chialis anticus; below the tendon of the biceps muscle, we meet with, first, the pronator radii teres in apposition with its internal edge ; and, next, the flexor carpi radialis. In contact with its posterior face superiorly is the supinator radii brevis ; below this muscle the tendon of the pronator radii teres ; and still lower down the flexor longus pollicis. The supinator radii longus, in addition to its action as a supinator of the hand, is a flexor of the fore-arm upon the arm. 2. Extensor carpi radialis longior, ( radi- alis externus longior, Soemm., humero sus-me- tacurpien, Chauss., Dumas,) arises from the lower extremity of the ridge above referred to, and from the outer condyle. Advancing for- ward it passes over the front of the elbow- joint, and soon becoming tendinous on its an- terior surface descends on the anterior part of the fore-arm, partly overlapped by the tendon of the supinator radii longus — its tendon gra- dually seeks the posterior part of the arm, and running through a broad shallow depression appropriated to it and the second radial exten- sor, finishes its course by being inserted into the back part of the metacarpal bone supporting the index finger. This muscle, as its name implies, is an extensor of the hand, possessing also a slight power in effecting its abduction. In the ulnar section of the anterior super- ficial antibrachial region we find five mus- cles. 1. Pronator radii teres arises tendinous, above the elbow-joint from the intermuscular ligament of the upper arm, from the front part of the internal condyle of the os humeri, from the process of fascia separating it from the flexor carpi radialis, and from the ulna close to the insertion of the brachialis anticus. This muscle, though tendinous at its origin, soon becomes fleshy, and from its rounded form, which causes a distinct projection beneath the skin at the front and upper part of the fore-arm, derives its name. Its fleshy fibres terminate in a tendon as it enters the radial section, which gradually be- comes wider as it descends, and sliding behind the supinator radii longus and extensor carpi radialis and in front of the radius, is inserted into the outer and back part of that bone. The pronator radii teres has to its outer side, supe- riorly, the tendon of the biceps muscle; below the tubercle of the radius it has the internal edge of the supinator radii longus in apposition with it, and as it slides in a spiral direction round the radius, and behind this muscle, it has the supinator radii brevis superior and external to it ; to its inner side it has throughout its course the flexor carpi radialis. In the ulnar section the anterior surface of this muscle is in contact with the fascia; in the radial it is covered by the supinator radii longus, the two radial extensors, and crossed by the radial artery and nerve. The posterior surface of this muscle is in contact with the anterior ligament of the elbow-joint, the bra- chialis anticus, the median nerve, ulnar artery, the flexor communis digitorum sublimis and radius. This muscle, while presenting a smooth and tendinous face to the under surface of the supinator longus and radial extensors, conti- nues fleshy on its under surface to the very point of its connexion with the radius, the muscle beneath, whose surface is in contact with its fleshy fibres, being clothed in a similar manner with tendon; this admirable contri- vance for preventing friction is by no means peculiar to this situation, though its utility is frequently overlooked. The name of this muscle indicates its action as a pronator of the hand, and when that effect has been produced, if its contractile power be still further excited, it will flex the fore-arm upon the upper. In case of fracture of the radius, this power is excited injuriously in bringing the radius across the ulna, and thus obliterating the interosseal space, and if not corrected by the surgeon, causing unnatural union of the two bones. 2. Flexor carpi radialis ( M. radialis internus, Winslow, Albinus, Lieutaud, Sabatier, Soemm. ; grand palmaire, or radial anterieur, Cloquet ;) arises from the internal condyle of the humerus in common with the last-mentioned muscle; at the point where these two muscles are con- nected with the humerus there exists no na- tural separation between them. About an inch and a half from their origin a separation is effected by the dipping in of the fascia forming MUSCLES OF THE FORE-ARM. 367 one of the muscular septa previously referred to. At the lower part of the upper third of the fore- arm their separation is complete. The flexor carpi radialis first changes its muscular fibres for tendinous on its anterior face, and a rounded tendon is the result at the upper part of the lower third of the arm. This tendon passes in front of the wrist-joint and through a groove in the os trapezium, is ultimately inserted into the base of the metacarpal bone supporting the fore-finger. This muscle has on its outer edge, in the superior third of the fore-arm, the pronator radii teres, in the two inferior thirds the supi- nator radii longus ; the palmaris longus to its inner edge, both at its origin and throughout its whole course in the fore-arm. Anterior to it there is simply the fascia, its posterior face is in contact with the superficial flexor of the fingers above and the long flexor of the thumb below. The tendon of this muscle projects distinctly through the skin at the lower part of the arm. The flexor carpi radialis, besides flexing the whole hand on the fore-arm, bends the second row of carpal bones upon the first. It will also act as an abductor of the hand, in consequence of its being fixed on the outer side of the hand in the pulley-like groove of the trapezium through which it passes. It slightly assists the pronator muscles in their influence over the hand. 3. The palmaris longus, Soemm., epitrochlo- palmaire, Chauss. The origin of this muscle, which is in common with the other flexors, is from the inner condyle, also from a tendinous intermuscular septum which separates it from the flexor carpi radialis on the outer side and the flexor communis digitorum on the inner. This muscle, the smallest of those situated in the fore-arm, becomes tendinous midway be- tween the elbow and wrist-joint. This tendon, which is narrow and slender, descends to the annular ligament, and is ultimately connected with the palmar fascia. This fascia has some- times been considered as a mere expansion of the tendon of the palmaris longus, but as the muscle is occasionally wanting and the fascia never, we regard it rather as another instance of that useful connexion of muscles with fascia; which we have already had occasion to admire. This muscle, except at its origin where it has the flexor carpi radialis to its inner side and the flexor communis to the outer, maintains a posi- tion completely superficial to the other muscles, its posterior face lying upon the flexor communis sublimis. This muscle flexes the hand, and makes tense the palmar fascia and annular ligament, and thus takes off from the palmar vessels and nerves and the tendons of the digital flexors the pressure to which they are exposed when the hand grasps a solid body firmly; as, for in- stance, when the whole weight of the body is sustained, as in the case of the sailor climbing the rigging of a vessel, by the power of the flexors of the fingers and hand. 4. Flexor communis digitorum sublimis per- forutus. ( Muse ul us perforatus, Soemm., epi- troehlo-phalanginien commun, Chauss.) This muscle also arises from the inner condyle in common with the other muscles, and from a strong tendinous septum separating it from the flexor carpi ulnaris. About the middle of the fore-arm this portion of the muscle is joined by muscular fibres which arise from the radius im- mediately below the insertion of the supinator radii brevis, and on the inner side of the pro- nator radii teres. Between these two origins of the flexor communis digitorum is placed the median nerve. The tendinous fibres, into which the muscle is gradually transformed, become first apparent on the anterior surface, and next being collected ultimately split into four cords, which passing behind the annular ligament of the wrist, enter the palm of the hand ; oppo- site the first phalanx of the four fingers these cords, splitting into two portions and allowing the passage of the deep flexors, terminate by being inserted in the rough edge on the sides of the second phalanges. The tendons of this muscle as well as the deep flexor are bound down to the phalanges by smooth tendinous sheaths or thecal which are dense and firm be- tween the articulations, but insensibly disap- pearing opposite the joint, where their presence would interfere with the motion of the parts; they are lined by synovial membrane to prevent unnecessary friction. Although the lateral width of this muscle is considerable, only a very narrow edge is in contact with the fascia, the remainder being covered by the last-mentioned muscles, so that some anatomists have described it as constitu- ting a middle layer. On the internal edge is placed the flexor carpi ulnaris, which maintains the same relative position to it throughout the fore-arm. In contact with its posterior face we have the flexor digitorum profundus, the flexor longus pollicis, and the ulnar artery, vein, and nerve. This muscle flexes the second phalanx on the first, and the first on the metacarpus, and the whole hand on the fore-arm. 5. Flexor carpi ulnaris, (musculus ulnaris internus, Soemm, cubital interne, Portal, cu- bito-carpien, Chauss.) This muscle arises from the internal extremity of the internal condyle of the humerus from the tendinous intermuscu- lar septum, between it and the flexor carpi digi- torum sublimis, and from the olecranon process of the ulna; between these two heads the ulnar nerve is situated ; its origin from the ulna is not limited to the olecranon process, for it con- tinues its connexion with that bone nearly as low down as the origin of the pronator quad- ratus. This muscle, which arises tendinous and fleshy, merges into tendinous fibres on its anterior surface at the upper part of the lower third of the fore-arm. The tendon by degrees becomes more rounded, but does not cease to receive fleshy fibres until it terminates by be- coming inserted into the annular ligament and os pisiforme. The flexor carpi ulnaris, forming the inner margin of the muscles of the fore-arm, is in contact witli the fascia: its external edge touches 368 MUSCLES OF THE FORE-ARM. the flexor communis digitorum sublimis. The relation of this muscle to the ulnar artery has induced some anatomists to denominate it muscle satellite de I'artire cubitale. In addition to its power as a flexor of the hand on the fore-arm, this muscle adducts the hand, drawing it towards the mesial line. b. The deep layer of muscles. — These are three in number, the flexor longus proprius pollicis, flexor communis digitorum profundus perforans, and the pronator quadratus. A por- tion of the supinator radii brevis is also found in it. 1. The flexor longus proprius pollicis, Scemm. ( ' Radio -phalangettien du pouce, Chauss.) This muscle, situated most exter- nally, arises by two heads ; one, narrow, rounded, tendinous, and fleshy, from the inner condyle of the humerus; the other, broad and fleshy, from the front of the radius, below the insertion of the biceps and supinator radii brevis, and from the interosseal ligament, extending as low down as the insertion of the pronator quadratus. Its tendon, first formed on its internal and anterior edge, descends behind the annular ligament of the wrist-joint, and taking its course between the two heads of the flexor brevis pollicis, is inserted into the last phalanx of the thumb. This muscle is covered anteriorly by the supinator radii longus and extensor carpi radialis iongior, except at the lower part, where it is simply covered by the deep fascia on which the radial artery lies. To its inner side is the flexor digitorum profundus. This muscle is a flexor of the last phalanx of the thumb, a powerful and important muscle in grasping objects. 2. Flexor communis digitorum profundus perforans. ( M. perforans, Scemm. M. cubito- phalangettien commun, Chauss.) arises tendi- nous from the front of the ulna immediately below the insertion of the brachialis anticus into the tubercle of that bone, and from the same as low down as the pronator quadratus ; also from the interosseous ligament. It becomes tendinous on its anterior face about the middle of the "ore-arm, thus presenting a smooth and polished surface to the muscles in front of it : like the superficial flexor, it forms its four tendons, which, after traversing the palm of the hand and piercing the split tendons of the superficial flexor, are ultimately inserted into the third phalanx of each of the fingers. This muscle has the flexor longus pollicis to its outer side ; the flexor carpi ulnaris to its inner ; and the flexor carpi radialis, flexor com- munis digitorum sublimis and palmaris longus, anterior to it. To flex the fingers on the hand, commencing with the flexion of the last phalanx on the others, and the whole hand on the fore-arm, constitutes the principal action of this muscle. 3. Pronator quadratus, Scemm. ( Cubito- radial, Chauss.) This muscle, entirely covered by those mentioned above, presents a beauti- ful appearance on their removal, from the ten- dinous surface admitting by its transparency the colour of the muscle to shine, as it were, through it. It arises from the ulna about an inch and a half above the wrist-joint, occupying exactly that extent of the surface of the bone with its attachments : it is inserted fleshy into the lower part of the radius. This muscle, simple as its action appears, that of rolling the radius over the ulna, per- forms a most important part in those easy mo- tions of the hand which the artist uncon- sciously produces when he is engaged sketching in bold and flowing lines the subject of his picture. To the surgeon a knowledge of the attach- ments of this muscle is peculiarly important, for in those cases in which the radius is frac- tured near its lower extremity it draws the injured bone into the field of the flexor tendons, and by bringing it into close contact with the ulna, produces a deformity which great care will alone obviate. Posterior antebrachial region. — If we now look to the posterior part of the fore-arm, we shall find that though it may be divided into radial and ulnar sections like the anterior, the propor- tions between them will be very different ; for one- fifth of the transverse diameter of the arm alone can be correctly allotted to the radial region in the upper part, and two-fifths close to the wrist- joint. The line of demarcation between these two regions is accurately formed in the dissected arm by the radial edge of the extensor com- munis digitorum. This muscle, like those on the anterior surface of the arm, is wide and muscular above, tendinous and comparatively narrow below ; and hence we find the radial section wider below than it is above. In the ulnar section, we have the extensor communis digitorum to the outer side; in contact with this muscle, on its ulnar side, is the extensor carpi ulnaris. This muscle, at its origin at the upper part of the arm, is narrow, and the space, thus yielded as it were by its form, is occupied by the anconeus, which forms the boundary of this region on the ulnar side. The space left at the lower part of the arm, from the divergence of the tendons of the extensor carpi ulnaris and extensor communis digitorum, permits a view of the indicator. The radial section contains at its upper part solely the extensor carpi radialis brevior ; but at the upper part of the middle of the arm, we have sliding into it from behind the extensor communis digitorum, the extensor ossis meta- carpi pollicis, and extensor primi internodii pollicis. These pursue their course obliquely across the radial section till they reach the outer edge of the arm. Lower down than these muscles and scarcely in contact with their inferior edges, we discover the tendon of the extensor secundi internodii pollicis likewise emerging from beneath the extensor communis digitorum. a. Superficial muscles of the posterior anti- brachial region. — 1. Anconeus ( epicondylo- cubital, Chauss.) though usually described as a distinct muscle, is, in reality, a continuation MUSCLES OF THE FORE-ARM. 3C9 of the triceps extensor cubiti: the fibres of each are perfectly continuous, and there is no line of demarcation between them. An artificial boundary may be made by drawing a line horizontally inwards when the fore-arm is ex- tended on the upper arm, between the outer condyle of the os humeri and the olecranon process of the ulna. With this view of the limit of the upper edge of the anconeus, it may be described as a triangular muscle, the base above and the apex below. This muscle arises ten- dinous from the back part of the outer condyle, its external and anterior edge continuing ten- dinous almost to its insertion ; its superior fleshy fibres pass transversely inwards and backwards, to be inserted into the fascia of the fore-arm and also into the olecranon ; the middle and inferior fibres pass backwards to the ulna with various degrees of obliquity, and occupy by their insertion about one-third of the bone from its superior extremity. This muscle is a simple extensor of the fore-arm. 2. Extensor carpi ulnaris, (ulnaris exter- nus, Scemm.; cubito sus-metucarpien, Chauss.) arises from the back part of the outer con- dyle between the anconeus and the extensor communis digitorum, with which latter muscle it is so intimately connected that, more strictly speaking, it ought to be said to arise in a common tendon. Connected by a narrow origin to the humerus it gradually expands, and about the middle of the fore-arm, a tendon being formed in the centre, it exhibits in its further course a well-marked specimen of the double penniform muscle. The tendon of this muscle, in its passage towards the wrist-joint, runs in an especial groove appropriated for its reception in the back part of the ulna ; it ter- minates by being inserted in the metacarpal bone supporting the little finger. The extensor carpi ulnaris is more or less connected with the fascia throughout the whole of the upper arm. This muscle extends the first row of carpal bones on the second and the whole hand on the fore-arm ; it is likewise an adductor of the hand. 3. Extensor communis digitorum ( epicondylo sus-phalangettien commun, Chauss. Dumas) arises from the back part of the outer condyle in common with the extensor carpi ulnaris on its outer side, and the extensor carpi radialis brevior on its inner side. The connexion of this muscle to the os humeri is extremely narrow in comparison with the width of the muscle in the centre of the fore-arm. In its ample attachment to the fascia it resembles the flexor ulnaris, and, like it, is a penniform muscle. We not unfrequenly find a portion of this muscle so entirely distinct from the rest that anatomists have occasionally described it as a separate muscle, under the name of the extensor proprius minimi digiti ; for being inserted into the little finger, it possesses the power of extending that portion of the hand. It passes behind the posterior annular ligament of the wrist-joint, splits into four tendons, which, expanding on the back part of the phalanges of the four fingers, convey the power VOL. II. of the muscle to each phalanx in an equal degree. The tendons of this muscle in their passage behind the annular ligament of the wrist-joint are clothed by a synovial membrane (reflected like all other synovial membranes) so as to form a perfect purse or bursa. Both these muscles are intimately connected upon their under surface at the upper part of the arm, with the aponeurosis covering fhe supi- nator radii brevis. This muscle is an extensor of the fingers and the hand on the fore-arm. 4. Extensor carpi radialis brevior, (radialis externus brevior, Soemm. Epicondylo sus- mctacurpien, Chauss. Dumas), with a small portion of the extensor carpi radialis longior, occupies the radial division of the poste- rior superficial antibrachial region. This muscle arises from the outer condyle by a flattened narrow origin, in common with the extensor communis digitorum, being overlapped on its outer side by the extensor carpi radialis longior. This muscle, like most we have described in the fore-arm, swells out towards the centre, where, gradually becoming tendi- nous, it again diminishes in size. It passes the same groove in the radius as the extensor carpi radialis longior, and terminates by an insertion into the metacarpal bone of the middle finger. The under surface of this muscle is tendinous at the upper part of the arm, which permits it to play without friction upon the smooth and tendinous face of the supinator radii brevis with which it is in contact. This muscle acts as an extensor of the hand on the fore-arm and an abductor. b. Deep muscles of the posterior antibrachial region. — The muscles in this region com- mencing above, are the supinator radii brevis, the extensor ossis metacarpi pollicis, the, exten- sor primi internodii pollicis, the extensor secundi internodii, and the indicator. 1 . Supinator radii brevis, ( epicondylo-rcidial, Chauss.) arises tendinous from that portion of the outer and back part of the ulna, unoccupied by the insertion of the anconeus; it arises also from the back part of the outer condyle, covered at its origin from the outer condyle by the extensor communis digitorum and by the exten- sor carpi radialis brevior. Its posterior and external surface is tendinous, its internal fleshy, and it embraces so much of the upper extremity of the radius, as to form an imperfect tube. Anteriorly we find it partly overlapping the tubercle of that bone, with the tendon of the biceps which is inserted into it. Between these and the under surface of the muscle is a large and distinct bursa mucosa ; it covers rather more than the upper third of the radius by its insertion, extending as low down as the pro- nator radii teres. This muscle is the main agent in effecting the supination of the hand. 2. Extensor ossis metacarpi pollicis, (ab- ductor longus pollicis manus, Scemm. cubito- radi sus-rnetacarpien, Dumas,) arises from the ulna, interosseous ligament, and the back part of the radius, opposite the insertion of the pronator radii teres, having to its outer side the supi- '1 2 B FOURTH PAIR OF NERVES. nator radii brevis, to its inner the extensor primi internodii pollicis. It is covered posteriorly by the extensor communis digitorum and extensor carpi ulnaris. Gliding downwards and out- wards from beneath these muscles and becoming tendinous on its under surface, it slips over the lower third of the posterior face of the radius, and then running in a groove on the outer side of that bone, common to it and the next men- tioned muscle, is ultimately inserted into the metacarpal bone of the thumb. The action of this muscle is to extend the metacarpal bone of the thumb, which corre- sponds as regards its capacity for motion, with the phalanges of the fingers. 3. Extensor primi internodii ( extensor minor pollicis munus, Scemm.; cubito sus- phalangettien du police, Chauss.) is a very small muscle compared with the last, though varying much in size in different subjects. It lies between the extensor ossis metacarpi pollicis and the extensor secundi internodii, passing through the same groove in the radius as the extensor ossis metacarpi pollicis, it becomes inserted into the first phalanx of the thumb. 4. The extensor secundi internodii pollicis ( extensor major pollicis munus, Scemm. ; cubito sus-phalangettien du pouce, Chauss.) — This muscle is usually larger than the former; it arises fleshy from the ulna and interosseous ligament ; becoming tendinous in its centre, it presents the same penniform appearance referred to above. The groove in the radius which is narrow and deep, this tendon alone being lodged in it. It is situated between that for the two radial extensors and the broad and hollow one for the common extensors and indicator. Crossing on the back of the wrist the radial extensors it is finally inserted into the second phalanx of the thumb. This mus- cle is entirely covered in the fore-arm by the common extensors of the fingers. 5. The indicator (cubito sus-phalangettien de I'index ) occupies the remaining portion of the posterior interosseal space. Like the three last described muscles it is penniform, and arises fleshy from the ulna and interosseous ligament, it descends to the hand and passes through the same groove at the back of the radius as that of the extensor communis digi- torum, it is inserted into the posterior surface of the three phalanges of the index finger. This muscle is entirely concealed by the exten- sor carpi ulnaris and extensor communis digi- torum. The names of this and the two preceding muscles indicate their actions. For Bin-iocbaphy, see Anatomy, (Intro- duction.) (Samuel Solly.) FOURTH PAIR OF NERVES (nervus trochleuris, s. patheticus ). — The fourth pair is the most slender of the encephalic nerves. They are intermediate in the 'Order of succession to the third or motor oculiand the fifth nerves, and hence the name. Each nerve is attached at its encephalic extremity to the lateral part of the superior surface of the anterior medullary velum or valve of Vieussens, immediately behind the testes or the posterior of the tubercula quadrigemina. It is divided at its attachment, for the most part, into two roots, inserted at a little distance from each other, one close to the testes, the other posterior to it. Occasionally it has but one root and sometimes even three. Gall and Spurzheim* are of opinion that the nerve might be traced to a more remote point, and according to Mayof " its fibrils appear to pass through the filaments of the pillar of the valve, and in part to arise from the back part of the medulla oblongata." The nerve is concealed at its insertion by the superior vermiform process of the cerebellum, and it is not immediately provided with neu- rilemma, and hence, as also because of its delicacy, it is very easily broken off. Its course within the cranium is circuitous and long, longer than that of the other nerves. It passes outward, downward, and forward : it first descends external to the superior peduncle of the cerebellum (the processus a cerebello ad testes), between it and the vermiform process, then becomes invested with arachnoid mem- brane and free, and runs round the lateral part of the crus cerebri, above the superior margin of the pons Varolii, and beneath the free edge of the tentorium cerebelli, until it reaches the posterior clinoid process of the sphenoid bone; it then enters the outer wall of the cavernous sinus between the points of attachment of the tentorium, and is transmitted through a canal in the dura mater, by which the wall is formed, forward to the foramen lacerum of the orbit. It does not enter the sinus, being contained in a canal in its outer wall. At the posterior part of the sinus the nerve is situate beneath the third, between it and the first division of the fifth nerve; but at the anterior, and as they are about to pass into the orbit, the fourth and frontal branch of the fifth are both above the third, the fourth internal and a little superior to the frontal. The nerve lastly enters the orbit through the superior part of the foramen lacerum in com- pany with the frontal, above the levator palpebral muscle, and immediately beneath the roof of the region. Having entered, it runs forward and inward, gains the surface of the superior oblique muscle, and attaching itself to it upon its superior aspect, about its middle, it divides into filaments, which are all distributed to the muscle. The fourth nerve does not give off any branch during its course to the oblique muscle, unless, at times, first a filamentdescnbed by Cruveilhier, and, according to him,distributed to the tentorium cerebelli. This filament arises from the nerve while traversing the wall of the cavernous sinus, runs backward into the substance of the ten- torium, and divides into two or three branches: Cruveilhier calls it " the branch of the tento- rium." Secondly, according to both Swan and Cruveilhier, the fourth nerve gives off a fila- * Anatomie Ju Systeme nerveux. f Physiology. GANGLION. 371 ment to the lachrymal branch of the fifth. Before its entrance into the orbit the nerve receives a filament from the sympathetic,* and at or immediately after entering, it receives one also from the frontal branch of the fifth, by the accession of which it is sensibly increased in size. It is very closely connected to the frontal itself at the back of the orbit. Upon the fourth nerve the power of the superior oblique muscle is considered to depend. It is remarkable that this muscle should be provided with an especial nerve, differing, apparently, so much in its encephalic relations from those by which the others are supplied ; but the theories which have been advanced upon the subject are as yet so unsubstantial, that we think it better to leave them untouched. (See Orbit, muscles of the). The nerve exists with similar relations in all the veriebrata. For the Bibliography, see Nerve. (B. Alcock.) GANGLION, (Gr. yayyXiov, Germ. Nerven Knoten.)— This term is applied to several dis- tinct structures : to the nodules placed on cer- tain nerves, to the lymphatic glands or gan- glions, to certain bodies, as the thyroid, the thymus, &c, which have been called by some anatomists vascular ganglions, and lastly, in surgical language, to the enlargement of the synovial bursas. It is, however, most gene- rally applied to the ganglions of the nerves; but of late years many anatomists, who con- ceive that the various masses of grey matter met with in the encephalon and spinal chord are, together with the ganglia of the nerves, sources of nervous power, have extended to those masses the general term of ganglion. Although there can be no doubt that the analogy has a real foundation, and that this application of the word is both convenient and correct, it is nevertheless proposed, in obe- dience to custom, to retain the old and more limited sense of the term ganglion, and to devote the present article to the structure of the ganglions of the spinal and sympathetic nerves, referring the reader for an account of the functions of these bodies to the articles Nervous System and Sympathetic Nerve. The nervous ganglions consist of a number of oval or roundish organs connected with certain nerves, and placed deeply in the trunk of the body, to which they are confined, being situated, with the exception of those of the head, in the immediate vicinity of the vertebral column. Their number and size are subject to variation, not only in different persons, but even on the two sides of the same individual; the following is the enumeration which approaches nearest to the truth : thirty on each side of the body, placed on the posterior roots of the spinal nerves ; one on each side, situated on the larger origin of the fifth pair; the ganglions of the great sympathetic consisting of the follow- ing, connected on each side of the body with what * See Pauli in Muller's Archiv. for 1834. is regarded as the trunk of this nerve, viz. three cervical, twelve dorsal, three to four or five lumbar, three to five sacral ; to these we must add some large masses placed near the mesial plane, viz. two semilunar, three or four coeliac ganglions, and one cardiac ganglion, first de- scribed by Wrisberg, but which is occasionally deficient ; and lastly, forming a part of the great sympathetic, the ophthalmic, the sphenopala- tine, the otic, and the submaxillary ganglions, and a small body usually met with in the caver nous sinus, the cavernous ganglion. M. Hip. Cloquet has described in rather vague terms a small reddish mass placed in the anterior palatine canal, which he calls the nasopalatine ganglion ; but Arnold, Cruveilhier, and others deny, and with good reason, the existence of this body. A gangliform enlargement is con- stantly seen on the commencement of the ner- vus vagus, and a second lower down ; a similar swelling is also placed on the glosso- pharyngeal nerve (g. petrosum). Professor Miiller of Berlin has discovered above this enlargement a true ganglion on the the. glosso-pharyngeal (ganglion jugulare nervi glosso-pharyngei), occupying half or two-thirds of the trunk of the nerve, and being precisely to that nerve what the Intervertebral ganglion and the Gasserian are to the spinal nerves and the fifth pair. My colleague Mr. Walker has shown me this ganglion, which is placed in the upper part of the foramen lacerum basis cranii posterius, and corresponds to the above descrip- tion.* Arnold has further noticed that at the junc- tion of the superior twig of the Vidian nerve, or nervus innominatus, with the facial nerve, there is a gangliform swelling.f Mayer has discovered a minute posterior root of the sublingual nerve, with a ganglion on it, in some mammalia (ox, dog, pig), and in one instance in man. Thus the total number of ganglions in the human body amounts to about one hundred and twenty-seven, exclusive of the gangliform enlargements on the pneumo-gastric, glosso- pharyngeal, and the facial nerves. These bodies have been variously arranged . by writers on this subject ; thus by WeberJ they are divided into ganglions of reinforce- ment, such as those on the spinal nerves, and into ganglions of origin, of which those of the sympathetic, the ophthalmic, and the spheno- palatine are examples; whilst Wutzer,§ classing them according to their situation and relations, considers that there are three orders, 1. the cerebral ; 2. the spinal ; 3. the vegetative : the first comprises the Gasserian ganglion, the ophthalmic, and the ganglion of Meckel, to which must be added the otic ganglion of Ar- * This very interesting discovery confirms the opinion that the glosso-pharyngeal is, like the spi- nal and the fifth, a compound nerve of motion and sensation. See Medizinische Vereins-Zeitune. Berlin, 1833. t Icones Nerv. Corp. p. 2. tab. ii. and vii. t Anat. Compar. nervi sympath. § De corp. hum. ganglior. fabrica atquc usu, p. 52. 372 GANGLION. nold ; in the second order are enumerated the thirty spinal ganglions and the ganglionic en- largement of the nervus vagus and glosso-pha- ryngeus ; in the third division are included the ganglions of the sympathetic nerve. The former of these arrangements is objec- tionable, because offices are assigned to the ganglions the existence of which has not been ascertained ; and the latter is so far erroneous that in this classification the ganglion of the fifth pair is separated from the spinal, to which it is undoubtedly similar; whilst the ophthalmic and spheno-palatine are as incorrectly divided from the system of the sympathetic* In endeavouring to detect that which con- stitutes the essential difference among these numerous bodies, we ought to pay special attention to the character of the nerves which are attached to the ganglions. Taking this as the only rational guide, I should refer them to two classes. 1. Those which are placed on sentient nerves, comprising the Gasserian, the ganglion .of the glosso-pharyngeus, and the spinal ganglions The gangliform enlargement of the nervus vagus should be referred to this order, inasmuch as there can be little doubt, although this at present is not proved, that this nerve is compounded, like the spinal nerves, of motor and sentient fibrils, a surmise supported by the distribution of the vagus, and still more by the interesting discovery of my friend Mr. Solly, of the existence of certain motor fibrils in the exact part of the medulla oblon- gata, whence this nerve arises.f 2. Those which have connected with them both motor and sentient nerves, and are, as I believe, always in relation with contractile and sensitive structures : J those, namely, of the great sympathetic nerve, comprising the cer- vical, the dorsal, lumbar, and sacral, together with the cardiac, the semilunar and coeliac, also the ophthalmic, the spheno-palatine, the otic, submaxillary, and cavernous. These classes nearly correspond with the * The following is the classification of Mailer : 1. Ganglia of the posterior roots of the spinal nerves, of the larger portion of the nervus trige- minus, of the nervus vagus, and ganglion jugulare nervi glosso-pharyngei. 2. Ganglia of the great sympathetic. 3. Ganglia which occur at the points of junction of the cerebro-spinal nerves with the branches of the sympathetic, comprising ganglion petrosum nervi glosso-pharyngei, intumescentia gangliformis nervi facialis, ganglion spheno-pala- tinum, ciliare, oticum (probably). To which should bo added ganglion submaxillare. Handbuch der Physiol, der Menschen. Erster Band. p. 588. t According to the present opinion, the whole of the fibres belonging to the nervus vagus enter into the ganglion; and Bischoff imagines that this nerve derives its motor portion from the spinal accessory. The intimate relations between these two nerves require further investigation. X It cannot be too often repeated that sensibility, or, to speak more correctly, the capability of being excited by the contact of a physical agent, may exist without being accompanied wiih conscious- ness : the inner surface of the heart, of the blood- vessels, and intestine are as capable of being ex- cited as the skin or the retina ; but the impressions which they receive are not usually perceived by the mind. simple and compound ganglions of Scarpa* and Meckel.f There are occasionally found ganglia on other nerves ; thus, Mr. Swan X has noticed one on the posterior spinal nerve, where it is placed under the extensor tendons of the wrist. My friend Mr. Pilcher has also found in two subjects a gangliform enlargement on the internal nasal nerve, where it is lodged on the ethmoidal bone. It is necessary to remark that although the ganglia of the first class are placed on certain of those nerves which are commonly regarded as being subordinate simply to sensation, yet the highly important observations of Dr. M. Hall,§ which have, I conceive, opened an en- tirely new field in physiology, render it doubt- ful that those bodies are essential to the exer- cise of sensation. Organization. — Although the cerebro-spinal and sympathetic ganglia present some impor- tant peculiarities when contrasted with each other, particularly as regards the proportions of the grey and fibrous substances, still as both classes possess essentially the same struc- ture, they may with propriety be considered in a collective manner. Every ganglion contains two totally distinct substances which have a close relation to, and are, I believe, identical with the grey and fibrous matters, constituting the encephalon and other parts of the nervous system. It is true that the appearance of these bodies is in many respects dissimilar to that of the brain ; but at length it is universally admitted that differences in mere physical properties are unimportant, and do not constitute any test as to tlve essential structure of an organ. In the present instance the diversity may very readily be understood when the difference of situation is considered. The cerebral organ is enclosed in a cavity, the cranium, formed of some of the strongest bones of the skeleton, and hence, being effectually defended from the effects of motion and external pressure, all its parts are soft and delicate ; whilst the ganglia, placed on bones which move on each other, slightly it is true, are exposed to external compression, and consequently a much firmer texture is required. It is for this reason that these bodies are invested in a dense fibrous capsule, which is to them what the cranium is to the encephalon, and which furnishes in addition a number of internal processes surrounding each fibril, and sustaining the spherical masses of grey matter. The difficulty of detecting the intimate texture is by these means greatly increased ; but as it is so similar to that of the cerebrum, it is desirable to examine the con- stituent parts according to the order observed in investigating that organ. I. Reddish grey matter. — The quantity of this substance, often called the peculiar matter of the ganglions, but which, as I have stated, * Anat. Annotat. liber primus. De nerv. gang, et plex. p 9. t Man. d'Anat. i:. i. ^231. i On the Nerves, pi. xxii. fig. 3. § Lcct. on the Nerv. Sys. 183b'. GANGLION. 373 is possessed by those bodies in common with the brain and spinal chord, is very considerable, constituting apparently the largest, and cer- tainly the most essential part of the ganglion. It is so intimately connected with the fibres that these latter appear as if they were incrusted, being surrounded in every direction by this greyish matter; but although this intimate intermixture is very evident, no fibrils can be perceived actually terminating in or arising from the grey matter. A section of one of the sympathetic ganglia, the first cervical for ex- ample, displays this incrustation of the fibres and the interposition between them of rounded masses of the grey matter ; but the Gasseiian is in many respects the most favourable for ex- amination. Much difference of opinion exists concerning the true nature of this substance. Scarpa con- tends that it is not analogous with the grey matter of the brain, but that it consists of a fiocculent a, a, Fasciculi of splanchnic nerve. b, b, Fibres running through the ganglion. c, c, Branches collected from the former, and emerging. This juicy or gelatinous substance, which is met with in the spinal as well as in the sympa- thetic ganglia, does not, however, according to Lobstein, appear to be an essential part of the organization, as it varies in its proportion in different ganglia, and may even be absent ; nor, it is said, can it be assimilated with the grey matter of the brain. Ehrenberg also controverts the opinion that the ganglia resemble the grey part of the brain ; but although he has found by microscopical inspection, that these bodies contain an over- tissue loaded with a mucilaginous fluid, which becomes oily in obesity, and watery and abun- dant in anasarca. The accumulation of fat in the true ganglionic tissue has, however, been denied by Beclard, Wutzer, and others. Ac- cording to Bichat, whose opinions must always command our respect, " the ganglions have a colour very different from that of the nerves. They present a soft spongy tissue, somewhat similar to the lymphatic glands, but which has nothing in common either with the cerebral substance or with that of the nerves." It is stated by Lobstein, who has published one of the latest and most minute accounts of the structure and diseases of the sympathetic nerve,* that he has observed lying contiguous to the white and filamentous tissue another substance presenting a fiocculent appearance, with globules interspersed (muteries vel sub- stantia orbicularis tomentosa ), and which he regards as the second material of the ganglia. d, d, Fiocculent or orbicular substance placed be- tween and applied to fibres. e, e, Foramina perforating the ganglion. whelming proportion of large varicose tubes, similar to those of the fibrous portion of the brain, yet he has also shewn that they possess minute varicose fibres like those of the grey substance ; and what particularly is deserving of notice, he has detected in the muscles of the fibres granules similar to those which are found in the cervical portion of the brain.f * De Nervi Sympath. Humani, fabrica, usu, ct morbis, p. 66. t Structur des Seelenorgans bci Menschen uud Thiercn, Berlin, 1836, p. 31. Fig. 170. Semilunar ganglion, twice the natural lixe. 374 GANGLION. Notwithstanding these and other high au- thorities, the researches of many recent writers, which have thrown so much new and valuable light on the mutual relations of the component parts of the nervous system, leave little room for doubting the identity of these two sub- stances. The analogy of the whole nervous system tends to prove that this peculiar matter is nothing else than the grey substance ; in the Gasserian ganglion, indeed, the resemblance is so striking that no doubt of their identity can be entertained. This view of the subject was taken by Winslow, Johnstone, and others; and lately the existence of grey matter has been admitted by Dr. Fletcher, an assumption, indeed, which is the basis of his hypothesis, that the ganglionic system of nerves is the im- mediate seat of irritability.* II. Fibres. — This is a most important branch of the present inquiry, because a knowledge of the connexions of these bodies with the other parts of the nervous system and with each other, as well as of the internal disposition of their fibres, is indispensable to the investigation of their functions. The subject may be re- solved into two questions, a. What is the arrangement of the fibres in the ganglia ? b. What is the nature of the fibres which arc connected with the ganglia ? a. The internal disposition of the nervous filaments, owing to the very intimate relations subsisting betweeu them and the grey matter, is difficult to determine; and hence it has happened that great difference of opinion pre- vails on this point. I shall in the first place describe the arrangement in the most simple of these organs, and for that purpose shall select that of the portio major of the fifth pair. On inspection it is seen that the large coarse fibrils of the nerve on approaching the ganglion begin to spread out from each other, and although in its interior they are, as we have already observed, encrusted by the grey matter, yet, on scraping this away, the fibres may be seen still passing on uninterruptedly, but becoming more and more separated from each other. It is this disposition which Scarpa has aptly enough compared to a rope the two ends of which remain twisted, whilst in the middle the component threads are unfolded and pulled asunder. A similar, but less distinct arrange- ment exists in the spinal ganglia. Although the continuity of the fibres through the ganglion is easily demonstrated, yet it would be wrong to conclude that this passage is all that happens ; for in the first place the three branches of the trigeminal nerve which emerge from, are decidedly larger than the trunk of the same nerve which passes into the ganglion. Their physical qualities are also altered, especially as relates to their colour, which, instead of having the whitish aspect common to the proper fibres of the cerebro- spinal axis, is for some distance of the reddish hue proper to the ganglionic system ; and again it would be in opposition to all our notions of the properties of the grey matter * Rudiments of Physiol, st. ii. a. p. 87. to imagine that the fibres do not maintain intimate connexions with that substance, by which means its influence, whatever it may be, is communicated to those threads. In the sympathetic ganglions the internal formation is much more intricate ; and it is especially in reference to these bodies that so much diversity of opinion prevails among anatomists. The researches of Monro,* Scarpa,f and Lobstein,} as well as ocular inspection, prove that some fibres undoubtedly pass without interruption through the ganglion. On making a section of the first cervical ganglion, previously hardened by alcohol, fibres will be perceived, which, although se- parated from each other by irregular interstices filled with grey matter, are still continued uninterruptedly from one to the other ex- tremity. There are, however, besides these, other fibres, which are so complex that it is almost impossible to demonstrate their exact disposition. I believe, however, that, inde- pendently of those fibrils which run through the ganglion, there are some which terminate in, and others which arise from the grey matter in its interior. Fig. 171. Superior cervical ganglion of the great intercostal nerve of the right side. a, Trunk of the great intercostal nerve a little below the foramen caroticum. b, Trunk of the nerve below the superior cervical ganglion. c, c, c, c, The branches which from the three superior cervico-spinal nerves run to join the su- perior cervical ganglion of the great intercostal nerve, d, d, d, Nerves issuing from the superior cervical ganglion, e. Nervous fibriform stratum of the ganglion, f, Reticulated plexus produced by the mingling of the nervous fibres, g, Reticulated or plexiform nervous filaments. h, Nervous filaments variously mingled with others connected with the neighbouring cerebral and spinal nerves, t, The nervous filaments of which the trunk of the intercostal nerve below the superior cervical ganglion is composed. * Obs. on Nerv. Sys. p. 54. + L. c. p. 14, Tab. 1. fig. I, 2,3, 4. t L. c. Tab. tertia. GANGLION. 375 b. What is the nature of tlte fibres which are connected with the ganglia ? The very interesting inquiries of Brown, Darwall, Teale, Stanley, and others into the nature of those frequent affections now generally known under the term of neuralgic diseases, by which a new and unexpected light has been thrown on a most obscure branch of pathology, render this part of the present investigation of pre-eminent importance. The mutual in- fluence exerted by the cerebro-spinal axis and the great sympathetic on each other, in consequence of which disease of the brain and spinal chord may cause morbid actions and conditions of the organs of digestion, circulation, and secretion, and vice versa, can only be experienced by a reference to the relations which exist between these two great divisions of the nervous system. Unfortu- nately, however, this question, so important both as regards physiology and pathology, is not easily resolved on account of the difficulty in the present state of our knowledge of dis- tinguishing from each other the different species of fibres which enter into these organs. I shall in the first place speak of the fibres which are perceptible to the naked eye, and afterwards point out the information that has been afforded by microscopical examination. The intervertebral ganglia (and these ob- servations may be applied to those of the fifth pair, of the glosso-pharyngeal, and of the pneumo-gastric) receive fibres only from the posterior roots of the spinal nerves, which, since the researches of Bell, Magendie, and Mayo, have been regarded as being subordinate to sensation. But if the important principles announced by Dr. M. Hall be susceptible, as I believe they are, of that confirmation from anatomical examination of which at present they stand in need, then to the true sensiferous fibrils which enter these ganglia we must add what are called by Dr. Hall incident filaments. It is also a question which yet remains to be decided, whether the twigs that are known to run between the posterior roots of the spinal nerves and the sympathetic ganglions pass in reality from the former to the latter or from the latter to the former ; if, as appears most probable, these threads are furnished by the sympathetic, then it is to be presumed they are subsequently continued to the intervertebral ganglions. With respect to the sympathetic ganglions, the following are the only facts that are at this time established. 1. There are longitudinal commissural fila- ments by which the ganglia are joined to each other, and by which they are formed, however remote they may be from one another, into one great and extensive system. 2. There are fibrils which extend between the motiferous part of the cerebro-spinal axis and the sympathetic, but whether they are derived from the former or the latter is not de- cided. 3. There are sentient fibrils observing a similar disposition. As the anatomical facts by which these facts are established will be found under the head Sympathetic Nerve, only a few remarks are required in this place. 1. With respect to the longitudinal com- missural fibres, they are as necessary here as in other parts of the nervous system ; and although Bichat speaks of this connexion of the ganglions being occasionally absent, such deficiencies are extremely rare, and if they do really exist, must be regarded as an ab- normal state. The importance of this con- nexion is rendered apparent by the union of the several nodules placed on the trunk of the sympathetic, which is so constant that anato- mists were for a long time so far misled by it as to compare tliis gangliated cord with the common nerves of the body ; but it is perhaps still more striking in the commissural fibres, which are so invariably noticed passing from the sympathetic to the small ganglia of the head. 2 and 3. In consequence of the motor and sentient nerves of the head usually forming distinct trunks, the ophthalmic ganglion offers a natural analysis, as it were, of the connexion between the great sympathetic and the cerebro- spinal axis. One twig passes between this small body and the nasal nerve of the fifth pair (sentient); a second extends between it and the lower division of the third pair (motor). The dissections of Arnold prove that a similar connexion exists in the spheno-palatine, the otic, and the submaxillary ganglia.* Mayo has also ascertained that the branches placed between the ganglia of the great sympathetic and the compound nerves of the spine are of a twofold character, one set being attached to the sentient and the other to the motor root. The adjoining figure (7%. 172), copied from a dissection I made for this purpose, shows the mode of communication in the thorax. Fig. 172. a, Anterior root. c, Ditto, b, Posterior root entering the ganglion, d, Sympathetic ganglion. e, Filament of communication to posterior root. f, Filament of communication to anterior root. * These connexions are very beautifully repre- sented in his work, Icones Nerv. Capit. Tab. 5, 6, 7, and 8. On some points relative to the otic ganglion it has been proved by the dissections of Schlemm that Arnold was in error, especially as relates to the branch supposed to be furnished from the ganglion to the tarsor tympani. 376 GANGLION. Notwithstanding so many important points have been established, it must be confessed that much remains to be decided. Thus, for example, we perceive that the ganglion of Meckel, like the ganglions of the sympathetic in the neck, has connected with it a motor fibril ; but this fibril, as Arnold has observed, presents the whitish character and firm texture common to the cerebro-spinal nerves, and therefore, it must be presumed, passes from the portio dura to the ganglion, whilst the twigs uniting the cervical nerves and the sympathetic are reddish and soft, rendering it probable, as Fletcher supposes, that they are furnished by the ganglia. Such being the imperfect results of ocular inspection, we are naturally anxious to obtain more exact information, especially in reference to the character of the different orders of fibres which are connected with the ganglia. The microscopical observations which are being car- ried on at this time with so much zeal in Ger- many, and from the prosecution of which the most valuable evidence may be anticipated respecting the undecided points of minute anatomy, have already thrown some light on this interesting question. Thus Ehrenberg* has de- tected in the sympathetic not only the varicose fibres which some imagine are proper to that system, but also some of the cylindrical fibres of which the cerebro-spinal nerves are principally composed. According to Lauth and Remark, the nerves of organic life (i. e. of the sympa- thetic) consist for the most part of varicose fibres mixed up with a small proportion of cylindrical ; whilst those of animal life consist principally of cylindrical mingled with a few varicose fibres. This is the exact appearance which must have been anticipated, if the mu- tual interchange of fibres described by Bichat,f W. Philip,} Mayo,§ Fletcher,|| and others, really exist. It may here be remarked that although the accuracy of Ehrenberg's researches, confirmed as they have been by Muller, Purkinje, Valen- tin and others, is called in question by Krause, Berres, and Treviranus, yet the essential fact of there being a decided difference in the phy- sical character of different orders of nervous fibres, and, consequently, a test for their suc- cessful analysis, is universally admitted.^! Lastly, it is a question of great interest whether there are not, independently of the relations which exist between the sympathetic and the cerebro-spinal axis, fibres proper to the former, * h. c. p. 31. t An. Gen. i. p. 220. " The ganglions (of the sympathetic) like the brain furnish and receive their particular nerves." i On Vital Functions, and Gulstonian Lect. « Out. of Phy. 4th edit. p. 259. || Rud. of Phy. part ii. a. p. 76. ^ Since the above was written I have learnt that the doubts expressed by Treviranus, Arnold, and others, as to the correctness of the views of Ehren- berg, have been confirmed. Professor Muller attributes the appearance of the varicose fibres to artificial causes ; and it is said that Ehrenberg himself doubt3 if such fibres exist in; th"e" normal condition. which establish between them and the organs they supply with nerves most important con- nexions. Our present knowledge does not afford the means of solving this question ; and, although my attention has been particularly directed to this subject, still, as my observa- tions are as yet incomplete, I shall satisfy myself by expressing my conviction that such a system of nervous fibres does exist. Covering. — Every ganglion possesses two coverings: the outer one in the spinal ganglions is very firm, being derived from the vertebral dura mater, whilst in the sympathetic gan- glions it is composed of condensed cellular tissue. On raising very carefully the external capsule, a more delicate tunic is exposed, which adheres to the proper ganglionic tissue. Bloodvessels.— These bodies, like all other parts of the nervous system, are amply sup- plied with arterial blood. After a successful injection, two, three, or more arteries, derived from the neighbouring vessels, may be readily observed running to the ganglion. Each vessel, having perforated the coverings of the ganglion, forms according to Wutzer a plexus on the inner surface of the capsule, and at length sends de- licate branches into the pulpy matter, which, with the aid of the microscope, may be ob- served to run in the same direction with the nervous filaments. (See figs. 171, 172.) The exact mode in which these vessels terminate is unknown, but it is probable, as in the cerebro- spinal system, that each nervous fibre is ac- companied by a minute artery and vein. No lymphatics have been demonstrated, but ana- logy tends to prove their existence, and Lob- stein states that he has often seen them forming networks around the ganglions. Chemical composition. — The experiments performed by Bichat* and Wutzerf would tend to show that the substance of the ganglions is distinct in its qualities from the cerebral matter and also from that of the nerves. By boiling, it is at first hardened, but soon becomes softened ; maceration in cold water renders it more soft and pulpy, and if sufficiently prolonged, the water being frequently changed, it is converted into adipocire. It is liquefied by the alkalies, and is rendered crisp and hard by the acids and alcohol. Bibliography. — Haase, De gangliis nervor. Scarpa, Anat. Annot. Liber i. de nerv. gang, et plexibus. Monro, Obs. on nerv. system. Soem- mering, De corp. hum. fabric, t. iv. Bichat, Anat. gen. Wutzer, De corp. hum. ganglior. fabrica atque usu. This work contains an elaborate list of the various authors who have treated of the ganglions, and an epitome of their opinions. Lobstein, De nervi sympath. humani, fabrica, usu et morbis. F. Arnold, Kopfthiel des Vegetativen nervensystem, beim Menschen. J. Muller, Hand-- buch der Physiol, des Menschen, 1834. C. J. Eh- renberg, Structur des Seelenorgans bei Menschen und Thieren, Berlin, 1836 ; Anat. der Microsko- pischen Gebilde der Menschlichen Kbrpers. Wien. 1836. C R. D. Grainger.) * Anat. Gen. t. i. p. 226. + De Corp. Hum. Gang. Fabrica atque Usu, § 55. The reader will find in this work many de- tails relative to the above subject. GASTEROPODA. 377 GASTEROPODA, (yeumf, venter, nov<;, pes; Eng. Gasteropods ; Fr. Gasteropodes ; Germ. Buuchf'usser ; Mollusca Rcpentia, Poli.) Definition. — An extensive class of the Mol- luscous division of the animal kingdom dis- tinguished by the structure and position of their locomotive apparatus, which consists of a mus- cular disc attached to the ventral surface of the body, serving either as an instrument by means of which the animal can crawl, or in rarer instances compressed into a muscular mem- brane useful in swimming. Characters of the class. — Body soft, enclosed in a muscular covering, which, from its contrac- tility in every direction, produces great variety in the external form of the animal : the back is covered with a mantle of greater or less extent, which in most of the geneia secretes a shell either enclosed within its substance, or, as is more frequently the case, external and suffi- ciently large to conceal and protect the whole body, in which case it is often provided with an operculum capable of closing its orifice when the animal is lodged within it. The head is anterior, distinct, and generally furnished with two, four, or six tentacles, which are placed above the oral aperture, and merely serve as instruments of touch. The eyes are two in number, and are placed sometimes on the head itself, but more generally at the base, at the side or at the extremity of the tentacles ; they are always very small, and not unfre- quently wanting. The muscular disc which is subservient to locomotion is called the foot, and is generally broad and fleshy, forming a powerful sucker, bnt in some instances it takes the shape of a deep furrow, or is compressed into a vertical lamella. The respiratory appa- ratus varies in structure ; in some genera it is composed of vascular ramifications which line a cavity into which the respired medium is freely admitted. Others are provided with branchiae, adapted to the respiration of water, variously disposed upon the exterior of the body, or concealed internally. The heart generally consists of an auricle and ventricle, and is systemic, or, in other words, receives the blood from the organs of respiration, and propels it through the body. The seiuul organs vary in their structure in different orders ; in the greater number each individual is possessed both of an ovigerous and impreg- nating apparatus, but copulation is essentia! to fecundity: in many the sexes are distinct, and some are hermaphrodite and self-impreg- nating. Some species are terrestrial and others aquatic. In separating the Gasteropoda into orders, the naturalist finds in the position and structure of the branchial apparatus a character suffi- ciently obvious ; and as the arrangement of these organs is modified by the circumstances of each individual, and is generally in relation with the peculiarities met with in the internal organization of the animal, the branchiae are at present universally referred to as affording a convenient basis of classification. We shall in this article follow the arrangement adopted VOL. II. by Ferussac, of which, as well as of the systems of other zoologists, an outline is con- tained in the following table. Order I. NUDIBRANCHIATA* (Cuv.) Syn. Polybranchiata,-f and genus Doris, Blainville ; Gasteropodes Dermobranchcs,X Du- meril ; Gasteropodes Tritoniens, Lamarck. In these the branchiae are symmetrical, as- suming a variety of forms, but always placed upon some part of the back, where they are unprotected by any covering ; the animals may be provided with a shell or naked, but they are all hermaphrodite with mutual copulation, and marine. 1st Sub-order, Anthobranchiata,\ Goldfuss; Cyclobranchiata,\\ Blainville. 1st Fam. Doris. 2d Sub-order, Polybranchiata, Blainville. 2d Fam. Tritonia, fig. 173. 3d Fam. Glaucus, fig. 174. Fig. 173. Order II. INFE ROBRANC HI A TA , (Cuv. and Blain.) Syn. Gast. Dermobranches, Dumeril; Gasi. Fhyllidkns, Lamarck. In the Inferobranchiate Gasteropods the branchiae are arranged under the inferior border of the mantle on both sides of the body, or upon one side only : the mantle sometimes contains a calcareous lamella. All the genera * Nudns, naked •, branchiae, gills, t IToXuf , maruj ; branchiae. X Aep/ua, shin. § Av0o;, a flower. || Kux'htx;, a circle. 2 c 378 GASTEROPODA. are hermaphrodite with reciprocal impregnation, and marine. 1st Sub-order, Phyllidiadce, Cuv. 1st Fam. Phyllidia, Jig. 175. 2d Sub-order, Semi-phyllidiada, Lam. 2d Fam. Gastroplax, Blainville. 3d Fam. Pieurobranchus, Cuv. Fig. 175. Order III. TECTIBRANCHIATA* (Cuv.) Syn. Chismobnmches, Blainville; Gust. Adelobranches,-\ Dumeril; Gast. P/iyllidiens and Laplysiens, Lamarck. In tins order the branchia? are placed upon the dorsal aspect of the body, but are pro- tected by a fold of the mantle which almost always contains a shell presenting a rudimen- tary spire. They are all hermaphrodite like the preceding, and marine. 1st Fam. Dikera. 2d Fam. Altera. Order IV. PULMONALIA INOPER- CULATA, (Ferussac ) Syn. Pulmones, Cuv.; J Pulmobr (inches, Blainville; Gast. Trac/ielipodes,§ Lamarck. The respiratory apparatus is here adapted to the respiration of atmospheric air, and instead of being composed of branchial tufts or la- minae, consists of a cavity lined by the rami- fications of the pulmonary vessels, the entrance to which can be opened or closed at the plea- sure of the animal. Almost all the species are provided with a shell either turbinated or concealed within the mantle, but are never furnished with a calcareous operculum. Every * Tectus, covered, f A$r,Xo;, concealed. | Pulmo, lungs. § Tpap^nXof, tlie neck ; nov;, foot. individual is hermaphrodite, but mutual copu- lation is essential to fertility. Some are terres- trial, others inhabit fresh water, and some are marine. 1st Sub-order, Geophilida,* Ferussac. 1st Fam. Limax. 2d Fam. Helix. 2d Sub-order, Gehydrophilida,\ Ferussac. 3d Fam. Auricula. 3d Sub-order, Hygrophilida?,l Ferussac. 4th Fam. Limneeus. Order V. PULMONALIA OPERCU- LATA, (Ferussac.) Syn. Pectinibranchiatajj Cuv. ; Siphoni- branchiata,\\ Blain. The respiratory organs of the animals form- ing this order are similar in structure to those found in the last, but they differ materially in other points. In all the operculated division the shell is closed by a calcareous operculum not found in the last, and instead of that hermaphrodite condition of the sexual organs common to the inoperculated order, the sexes are distinct, the male and female parts existing in different individuals. They are all terres- trial. 1st Fam. Helicina. 2d Fam. Turbicina. Order VI. PEC TIN1 BRA NC HI A TA, (Cuv.) Syn. Trachelipodes, Lamarck ; Monopleuri- brunches, Blain. ; Gast. Adelobranches and Siphonibranches, Dumeril. This extensive order, which comprises most of the univalve mollusks whose shells enrich our cabinets, is characterized by a respira- tory apparatus adapted to an aquatic medium. The branchise are pectinated, consisting of ranges of fringes disposed like the teeth of a comb, and generally enclosed in a dorsal cavity which opens externally at the side of the body or above the head. The shell is always turbi- nated, and sometimes provided with an oper- culum. The sexes are separate, and the ani- mals fluviatile or marine. 1st Sub-order, Pomastomidaft Ferussac ; Chis- mobranches, Blainville. 1st Fam. Turbo, Lin. 2d Fam. Trochus, Lin. 2d Sub-order, Hemipomastomidte, Ferussac. 3d Fam. Cerithium, Adanson. 4th Fam. Buccinum, Lin. 5th Fam. Murex, Lin. 6th Fam. Strombus, Lin. 7th Fam. Conns, Lin. 3d Sub-order, Apomastomida, Ferussac. 8th Fam. 9th Fam. Volutu, Lin. 10th Fam. 4th Sub-order, Adelodermida, Ferussac. 11th Fam. Sigarelus, Adanson. * r», the earth ; $ iXem, to love. f Vn, the earth ; v$a>p, the water ; iX£ft>. $ Typt;, moist ; iAe«. § Pecten, -inis, a comb. || 2icfa)v, a canal. % Ua>jA.a, operculum; epai, to carry. t KaTiWTpa, a covering. 2d Fam. Capulus* 3d Sub-order, Heteropodaf Nucleobranches, Blainville. 3d Fam. Pterotrachea, Jig. 177. Order VIII. CYCLOBRANCHIATA, (Cuv.) Syn. Dermobranches, Dum.; Gast. Phylli- diens, Lam. ; Gast. Chismobi-anches, Blain. In this order the branchia; are arranged under the margin of the mantle around the circumference of the body ; the shell is a simple shield, either composed of one piece, which is never turbinated, or else made up of several divisions. They are all hermaphrodite and self-impregnating. 1st Sub-order, Chismobranchiata, Blain. ; Cy- clobranchiata, Goldfuss. 1st Fam. Patella. 2d Sub-order, Pulyplaxiphora,\ Blain. 2d Fam. Oscabrion. Cuvier detaches the genera Vermetus, Magi- lus, and Siliquaria from the Pectinibranchiata on account of the irregular form of their shell, which is only spiral at its commencement, and is usually firmly attached to some foreign body, a circumstance which involves as a necessary consequence the hermaphrodite type of the sexual organs, so that these genera are self- impregnating. He has, therefore, arranged them in a separate order, to which he applies the name of Tubulibranckiata, Tegumentary system. — The skin which in- vests the Gasteropoda varies exceedingly in texture, not only in different species but in dif- ferent pares of the same animal ; its structure being modified by a variety of circumstances connected with the habits of the creature, the presence or absence of a calcareous covering, or the mode of respiration. In the naked Gaste- ropods, especially in the terrestrial species, it is thick and rugose, serving as a protection against the vicissitudes consequent upon the changeable medium which they inhabit. In such as are aquatic the integument is proportionably thin- ner, and its surface more smooth and even ; in both, however, it differs much in texture in dif- ferent parts of the body ; thus in the dermo- branchiate species it becomes attenuated into a thin film, where it invests the vascular appen- dages subservient to respiration, and such por- tions as cover the organs of sense assume a transparency and delicacy adapted to the sen- sibility of the parts beneath. In those orders which are provided with shells, the integument which protects such parts of the body as are exposed when the animal partially emerges from its abode, is thick and spongy, and very different from the thin fibrous membrane which invests the mass of viscera contained within the shell. We are led by various circum- stances to presume that the skin of all the Gasteropods is in structure essentially ana- logous to that of higher animals, and in de- * Many of the CapuloiJ Gasteropods are thought by Cuvier to be dioecious. f E-ripoc, different ; Ttovt, foot. t rioXuf, many; ir'Ka^, a scale ; «, w,) the details of its arrangement are more minutely shewn; yet even in the beautiful drawing of Cuvier, from which our plate is copied, the minute divisions of this superb plexus are but inadequately shewn. The order which has been established by Ferussac, under the name of Pulmonalia operculatu, is composed of individuals classed by Cuvier among the Pectinibranchiata, to which in every cir- cumstance, with the exception of the struc- ture of the respiratory system, they are closely allied ; these, however, breathe the air in a cavity analogous to that which we have just described, only differing in the position and nature of the aperture leading to it, which here, instead of being a rounded orifice in the margin of the collar, opened and closed at the will of the animal, is a large fissure placed above the head, exactly as in the Pectinibranchiate order. Organs of circulation. — Having thus de- scribed the different arrangements of the branchiae, we shall be enabled more readily to investigate those modifications in the dis- position of the organs subservient to the cir- culation of the blood which are dependent thereupon. Throughout the whole class, with GASTEROPODA. Fig. 190. 391 the exception of the Scutibranchiate and some of the Cyclobranchiate orders, the heart is single, consisting of an auricular and ventri- cular cavity, and is interposed between the branchial or pulmonary vessels and the system, receiving the aerated blood from the respiratory organs, and propelling it through the body. The heart of Aplysia (fig. 191, e, g) or of the Snail, (fig. 190, o, p) will exemplify its ordi- nary structure. The auricle varies slightly in shape in different genera, but is always ex- tremely thin and pellucid, containing in its coats muscular bands of great delicacy. The ventricle is provided with stronger walls, and is generally separated from the auricle by a valve, formed of two pieces. The heart is en- closed in a pericardium, but its position is re- gulated by that of the branchiae; and from the great diversity of arrangement which we have found the latter to present, a corresponding want of uniformity in the locality which the heart occupies may be readily expected. We shall select two forms of the respiratory organ as examples of the variable position of the heart, and as illustrations of the usual distribu- tion of the bloodvessels, viz. the Snail, (vide Circulation, fig. 322, and the Doris, fig. 321,) and afterwards notice the principal aber- rations from the ordinary disposition. In the Snail, the blood derived from the whole body is brought by great veins, performing the func- tions both of the vena cava and of a pulmonary artery, to the plexus of vessels lining the floor of the respiratory cavity ; after here undergoing the needful aeration, it enters the heart, from whence it is driven into the aorta. The aorta immediately divides into two trunks, one dis- tributed to the liver, the intestine, and the ovary; the other supplying the stomach, the oral apparatus, the organs of generation, and the foot. In the Slug the arteries are perfectly white and opaque, and their ramifications, which may be traced with great readiness, are extremely beautiful. In Doris (fig. 321) the heart is, in conse- quence of the position of the branchiae around the anus, removed quite to the posterior extre- mity of the body. The blood derived from all parts of the body is conducted by large veins to the respiratory organs ; the pulmonary arte- ries which return it from thence unite into a circular vessel (b, b), surrounding the anus, and from this arise two vessels, emptying them- selves into the auricle. The aorta, on issuing from the heart, divides into two large vessels, the first supplying the intestinal canal, stomach, and duodenum, the organs of generation, the foot, and the mouth ; whilst the other large trunk is entirely distributed to the liver. In Tritoniu the heart is placed near the centre of the body, and the auiicle itself resem- bles a cylindrical vessel placed transversely 392 GASTEROPODA. across the other viscera, and communicating with the ventricle near its middle. The blood arrives at the heart through four vessels from the long fringe of branchiae, two comina; from the anterior and two from the posterior parts. We have already described the disposition of the branchiae in the Tectibranchiate order, but in following the course of the circulating fluid, we shall find in some of the individuals in- cluded in this division circumstances requiring special notice, as being of extreme interest to the physiologist. In Aplysia, the blood re- turned from the system is brought by two lars;e venous trunks to the vena cava or pulmonary artery (fig. 191, b); for in this case the same Fig. 191. vessel performs the functions of both ; these large veins turn round in the vicinity of the operculum, and unite into one trunk prior to their dispersion over the branchial plates, but on opening them at this point so as to display their interior, a most singular arrangement is brought to light; the sides of the veins are found to be formed of muscular bands (c) crossing each other in various directions, and leaving spaces between them ; these intervals are seen even by the naked eye to be apertures establishing a free communication between the interior of the vein and the abdominal cavity, and allowing injection to pass with facility from the vein into the visceral cavity, or from the abdomen into the vein : the anterior portion of each of these vessels may indeed be said to be literally confounded with the general cavity of the the body, a few muscular bands, forming no obstacle to a perfect communication, being the only separation between the two. It is there- fore evident that the fluids contained in the abdominal cavity may in this manner have free access to the mass of the blood as it approaches the respiratory organ, and that the veins can thus perform the office of the ab- sorbent system ; but in what mariner the blood is prevented from escaping through the same channels is not at all obvious, although pro- bably during life the contraction of the fasci- culi which bound these apertures may in some measure obstruct the intercourse. It is from this circumstance, and the analogous commu- nication which exists in the Cephalopoda by the intervention of the spongy appendages to the venaa cavae found in those Mollusks, that Cuvier was led to the conclusion that in all the class the veins are the immediate agents of absorption, and that an absorbent system does not exist in any but the vertebrate division of the animal kingdom. We meet, moreover, in Aplysia with another peculiarity in the cir- culating vessels; the aorta, shortly after its commencement, divides into two large arteries (A //'), one of which presents nothing peculiar in its distribution; but to the larger of the two, whilst still enclosed in the pericardium, we find appended a remarkable structure, the use of which has been hitherto perfectly inexpli- cable : projecting from the opposite sides of the vessel are two vascular crests, represented in if formed of a plexus of vessels issuing from the aorta itself, and ramifying in an ex- ceedingly beautiful manner through the sub- stance of these extraordinary organs ; in other respects the arteries are distributed in the usual manner. The Cyclobranchiate and Scutibran- chiate Gasteropods approximate the testaceous class in many points of their organization, but in none more so than in the position which the heart is found to occupy, and the arrangement of its cavities. In Patella, indeed, the heart is placed in the anterior part of the body, and still conforms in its general structure to the description which we have given above ; but in Oscabrio the auricle is divided into two distinct portions, one receiving the blood from each range of branchial plates ; and in Haliotis, Fissurclla, Emargenula, and Parmophorus, not only is this division of the auricle met with, but the ventricle, as in many of the testaceous Mollusks, is perforated by the rectum, and the similarity of arrangement which is here presented with what is met with in the Con- chifera will be readily appreciated by a refer- ence to the article which treats of the anatomy of that division of the Mollusca. Nervous system. — The nervous system of the Gasteropoda furnishes us with the most perfect form of the heterogangliate, or as it has been lesshappily denominated, cyclo-gangliated type. It consists of a variable number of ganglia or nervous centres disposed in different parts of the body, but connected with each other by cords of communication, and from these ganglia the nerves appropriated to dif- ferent parts proceed. Each ganglion, therefore, is a distinct brain; and were the preponderance in size to be regarded as the criterion of rela- tive importance, it would not unfrequently be hard to say to which the pre-eminence is due. There is, however, as we shall soon perceive, an uniformity in the arrangement of certain masses, and a regularity in the appropriation of the nerves proceeding from them to parti- cular organs, which leave us little room for GASTEROPODA. 393 hesitation upon this point ; before, however, entering upon a more detailed account, we will offer a few general observations upon this system, applicable to the whole class. The nervous centres are obviously of a different nature from the cords by means of which they are connected into one system, and from the nerves arising from them ; the nervous mass of the ganglion itself is generally granular in its appearance, whilst the texture of the nerves is homogeneous and smooth ; the distinction is, however, in a few instances, rendered still more remarkable by a striking difference in colour ; thus in Aplysia, whilst the nerves are of a pure white, the ganglionic centres are of a beautiful red tint; the same circumstance is met with in the Bulimus Stagna'is, and has also been remarked in many of the conchi- ferous Mollusca. A second peculiarity may be noticed in the mode in which the nerves and ganglia are invested with a neurilema or sheath, so loosely connected with them that it may be inflated or injected with great facility, and for this reason the nerves have been mis- taken for vessels by some authors. As an example of the most perfectly dis- persed arrangement of the nervous centres we shall select Aplysia, in which the ganglia are more numerous than in the generality of the Gasteropod Mollusks. In this animal we find a ganglion placed above the cesophagus to which the name of the brain is universally allowed, not so much on account of its size as because throughout the class it constantly occupies the same position, and as invariably supplies those nerves which are distributed to the most important organs of sense ; in this case its branches run to the muscles of the head and to the male organ of generation ; it likewise sends on either side a large branch to each of the great tentacles, which as they approach those organs give origin to the optic nerves. On each side of the cesophagus is found another ganglion equalling the brain in size, and constituting two other nervous centres, which are united to each other and to the brain by cords so disposed as to form a collar around the cesophagus; each of these gives off a number of nervous filaments, which are lost in the muscular envelope of the body ; a fourth ganglion joined to the brain by two cords is found under the fleshy mass of the mouth ; this supplies the cesophagus, the muscles of the mouth, and the salivary glands. At a considerable distance from these, and placed near the posterior portion of the body in the vicinity of the female generative organs and the respiratory apparatus, is a fifth gan- glion communicating with the second and third by means of two long nerves, and giving branches to the liver, the alimentary canal, the female generative system, as also to the branchiae and the muscles of the operculum. From this account it will be seen that none of these ganglia can be said to preside exclusively over any particular apparatus, branches from each being distributed to very different struc- tures ; but yet, speaking generally, there ap- vor,. ii. pears to be some reason for classifying their functions. Thus the brain is exclusively the centre of the principal senses : the two great lateral ganglia supply the bulk of the muscu- lar system ; the sub-oral ganglion is particularly subservient to mastication and deglutition, and the fifth or posterior nucleus being almost entirely appropriated to the supply of the digestive, respiratory, circulatory, and gene- rative viscera, might be regarded as analogous to the sympathetic. There are, however, but few of the Gasteropoda in which the ganglia are so distinct in position and function as in Aplysia. In the inoperculate pulmonary Gas- teropods, as in the Snail and Slug, the nervous centres are only two in number, namely, the brain, placed in its usual position above the cesophagus, and a large sub-cesophageal gan- glion connected with it by two cords embracing the oesophageal tube. The brain in this case supplies nerves to the muscles of the mouth and lips, as well as to the skin in their vici- nity ; it likewise furnishes the nerves of touch and of vision, besides those distributed to the generative organs, and from the sub-cesopha- geal ganglion, which fully equals the brain in size, arise those nerves which supply the muscles of the body and the viscera. There is, however, placed under the cesophagus a very minute nervous mass, which from the con- stancy of its occurrence is worthy of notice ; it is formed by the union of two minute nerves arising from the brain, and the little filaments which it gives off are lost in the cesophagus itself. One remarkable circumstance may be men- tioned as being probably peculiar to the class under consideration, namely, the changes of position to which their nervous centres are subject ; obeying the movements of the mass of the mouth, with which they are inti- mately connected, they are pulled backwards and forwards by the muscles serving for the protrusion and retraction of the oral appa- ratus, and are thus constantly changing their relations with the surrounding parts. In the Snail it would seem that the great size of the nervous collar which embraces the cesophagus will in some circumstances permit the mass of the mouth to pass entirely through it, so that sometimes the brain rests upon the oeso- phagus, and at others is placed upon the in- verted lips. In most of the Pectinibranchiata, the brain consists of two ganglia united by a transverse cord ; from these two centres arise the principal nerves, two of which unite to form a small ganglion beneath the cesophagus, from which that tube derives its peculiar supply. It is in the Nudibranchiate division, how- ever, that the nervous centres exist in their most concentrated form, and in these it is doubtful whether there are any ganglia, except the large supra-cesophageal brain. We may take Tritonia as an example of this form of the nervous system. In this beautiful Gasteropod the brain consists of four tubercles placed across the commencement of the cesophagus, the nervous collar being completed by a simple 2 D 394 GASTEROPODA. cord; all the nerves which supply the skin, the muscular integument, the tentacles, the eye, and the muscles of the mouth arise from the brain, and anatomists have not hitherto detected any other source of nervous supply, although Cuvier suspected two minute bodies, which he found beneath the oesophagus appa- rently connected with the brain, to be of a ganglionic nature. The slow-moving and repent tribes of which we are now speaking have their powers of sense almost entirely limited to the perception of objects in actual contact with their bodies, and instruments adapted to touch and vision are the only organs of sense which the anato- mist has been able to distinguish. The utter want of an internal skeleton or of an external ar- ticulated crust forbids us to expect that any of them are provided with an apparatus specially calculated to appreciate sonorous undulations. Their tongue, coated as it is with horny plates, studded with spines, or absolutely corneous in texture, is obviously rather an instrument of deglutition than an organ of taste. No re- searches have hitherto detected any part of the body which could be looked upon as devoted to smell ; the eye is generally a mere point, rather inferred to be such by analogy than clearly adapted to vision; and the sense of touch in fact is the only one which anatomical evidence would intimate to be perfectly deve- loped. Yet in spite of these apparent defi- ciencies, observation teaches us that many genera are not utterly deprived of the power of appre- ciating intimations from without connected with the perception of odours ; it has been found by direct experiment that some of them are pe- culiarly sensible of the approach of scented bodies ; thus the snail, although at rest within the shelly covering which forms its habitation, will with great quickness perceive the proximity of scented plants which are agreeable articles of food, and promptly issue from its concealment to devour them. Some anatomists have sup- posed that it is at the entrance of the respiratory cavity that we are to look for the special seat of smell, where, as the air alternately enters and is expelled by the movements of respiration, the odorous particles with which it may be impreg- nated are rendered sensible. Others with scarcely less probability conceive that the whole surface of the body which is exposed to the at- mosphere may be endowed with a power of smelling, the quantity of nerves which are dis- tributed to the integument, and the moisture with which it is constantly lubricated, seeming to adapt it perfectly to the performance of this function, giving it all the characters of a Schneiderian membrane. It is not impossible that sounds may be perceived in a somewhat analogous manner, although no proof has yet been adduced that any of the Gasteropoda are sensible to impressions of this nature. The sense of touch is exquisitely delicate over the whole surface of the animal, but more especially so in the foot, which is extremely vascular and abundantly supplied with nerves ; yet in spite of this delicacy in the organisation of the skin which makes it so sensible of contact, it appears to have been beneficently ordered that animals so helpless and exposed to injury from every quarter, are but little sensible to pain, and that such is the case, M. Ferussac, a diligent ob- server of their economy, bears ample testimony. " I have seen," says he, " the terrestrial gaste- ropods allow their skin to be eaten by others, and in spite of large wounds thus produced, shew no sign of pain." But besides the sen- sation generally distributed over the skin, we may observe in most instances organs of variable form which seem peculiarly appropriated to touch. These are the tentacles, or horns as they are usually termed, which occupy a va- riable position upon the anterior part of the animal. The tentacles vary in number in different genera : thus in Flanorbis we find two, in the generality of cases four; in a few, as some spe- cies of (Eolis, six ; and in Polycera even eight of these appendages are met with. The structure of the tentacles is by no means the same in all the individuals belonging to this class. In the aquatic species they are to a greater or less ex- tent retractile, but can in no case be entirely concealed within the body, as is usual in the terrestrial division ; they are therefore not hol- low, but composed of various strata of circular, oblique, and longitudinal muscular fibres, by means of which they are moved in every direc- tion, and applied with facility to the objects submitted to their examination. In all instances they are plentifully supplied with nerves arising immediately from the brain. Their shape is subject to great variation ; they are usually simple processes from the surface of the body more or less elongated, and in some cases even filiform, as in Planorbis. In Murex (Jig. 193) each tentacle is a thick and fleshy stem, near the extremity of which a smaller one is appended. In Tritonia each tentacle is com- posed of five feathery leaflets, and is enclosed in a kind of sheath which surrounds its base. In Doris the two inferior are broad, flat, and fleshy, while the superior are thick and club- shaped. In Scyllaa they consist of broad fleshy expansions attached by thin pedicles to the anterior part of the body. In Thethys they are placed at the base of the veil which characterises the animal, but in all cases they are solid and incapable of entire retraction. In the terrestrial Gasteropoda, in which from many causes the tentacles are more exposed to injury, a much more complicated structure is needed, by which these important organs are not only moved with facility in different directions, but which allows them to be perfectly withdrawn into the interior of the body, from which posi- tion they may be made to emerge at the will of the animal : the mechanism by which this is effected will be understood by referring to Jig. 192, representing a dissection of the common snail, and exhibiting the tentacles in different states of protrusion. Each tentacle (c, d,) is here seen to be a hollow tube, the walls of which are composed of circular bands of muscle, and capable of being inverted like the finger of a glove; it is in fact, when not in use, drawn with- in itself by an extremely simple arrangement, GASTEROPODA. 395 Fig. 192. Structure of the tentacle! in the Garden-Snail ( Helix Pomatia ). From the common retractor muscles of the foot four long muscular slips are detached, one for each horn ; these run in company with the nerve to each tentacle, passing within its tube when protruded, quite to the extremity (g). The contraction of this muscle dragging the apex of the organ inwards, as seen at c, of course causes its complete inversion, whilst its protrusion is effected by the alternate contrac- tions of the circular bands of muscle of which the walls of each tentacle are composed. There is, however, another peculiarity rendered neces- sary by this singular mechanism, by which the nerves supplying the sense of touch may be enabled to accommodate themselves to such sudden and extensive changes of position ; for this purpose the nerves supplying these organs are of great length, reaching with facility to the end of the tubes when protruded, and in their retracted state the nerves are seen folded up within the body in large convolutions. In the figure, a a indicates the origins of the retractor muscles of the foot from the columella; b, the right superior tentacle fully protruded ; c, the left superior tentacle partially retracted ; d, the left inferior tentacle extended, and e, the right inferior tentacle fully retracted and concealed within the body ; f\ the nerve supplying the superior tentacle elongated by its extension ; g, the retractor muscle of the same tentacle arising from the common retractor muscle of the foot and inserted into the extremity of the tube ; /), the nerve of the opposite side thrown into folds ; i, the retractor muscle of the same tentacle contracted ; k, the aperture through which the nerve and retractor muscle enter the tentacle d ; I, the brain ; m, the subcesophageal ganglion ; n, the eye. Vision. — The eyes of Gasteropoda are ex- tremely small in comparison with the bulk of the animals, and seem more to represent the rudiments of an organ of sight than to be adapted to distinct vision. In many species indeed they appear to be absolutely wanting. When found, they resemble minute black points, by far too email to admit of any satisfactory examination of their internal structure; and even in the largest forms of the organ which are met with in the more bulky marine genera, it is with difficulty that their organisation can be explored. In Jig. 193 we have delineated the position and structure of the eye in a large Murex. Fig. 193. Tentacles and eye of Murex. The natural size of the organ is seen in the upper figure, in which on the right side the organ is represented untouched, while on the left a section has been made to exhibit its interior. This section when magnified, as in the lower figure, shews us that it consists of a spherical cavity lined posteriorly with a dark choroidal membrane, and containing a large spherical lens ; the position and structure of the retina we have been unable satisfactorily to determine, although the visual nerve may be readily traced to the back of the choroid, where it seems to expand ; but whether, as in the Cephalopods, its sentient portion is spread out behind the pigment which lines the eye-ball, or whether, as in the forms of the organ common to the vertebrate orders, the retina is placed anterior to the choroid, is a question which we are at present unable to solve. But however this may be, we see anteriorly a distinct pupil surrounded by a dark radiating zone, apparently an iris, to which it corresponds at least in position, although that it is really capable of contracting or en- larging the pupillary aperture is more than our observations warrant us in affirming. Finding, therefore, the eye of the Murex to offer a struc- ture which indubitably entitles it to be regarded as an organ of sight, we are justified in consi- dering the more minute specks of smaller Gas- teropoda as similarly formed and subservient to the same office. In the aquatic species the eyes are generally placed at the base of the su- perior or larger tentacles, although not unfre- quently they are supported upon short pedicles appropriated to them, as is the case in Haliotis and others. In Murex we have seen that the tentacles which support them are large and 2 d 2 396 GASTEROPODA. fleshy, and by the position of the eyes at the extremity of so long a stem these can be readily directed to different objects. In no case, how- ever, can they be retracted within the body so as to be quite enclosed in the visceral cavity. In the terrestrial Gasteropods the eyes are gene- rally placed at the extremity of the superior horns, a position which manifestly extends the range of vision, and moreover, in consequence of the structure which we have described when speaking of the organs of touch, may be com- pletely drawn within the body. In jig. 189, b, the eye of Vaginulus is seen at the extremity of the upper tentacle, and the origin of the optic nerve (c ) from the brain (d), as well as the convolutions which it makes to allow of its adaptation to the varying length of the tentacle, and the bulb in which it terminates behind the eyeball (b*), are sufficiently displayed. In Jig. 192, b, the eye of the snail exhibiting the same circumstances has been represented, and the apparatus by which the movements of the whole organ are effected is so clearly shewn as to render further description superfluous. Generative system. — The description of the generative apparatus of the Gasteropoda forms one of the most remarkable parts of their history, and the complication which it presents in some orders is probably unique in the ani- mal kingdom. The class may be divided, as far as relates to this function, into three great divisions: — 1st. Hermaphrodite and self-im- pregnating; 2d. Hermaphrodite, but recipro- cally impregnating each other by mutual copulation ; 3d. Sexes distinct, the female being impregnated by copulation with the male. We shall consider each of these divi- sions in the order in which they have been enumerated. The lowest orders approximate the Conchifera in most parts of their organisa- tion, and in the arrangement of their generative system we need not be surprised to see a manifest resemblance. The Scutibr uncinate and Cyclobranchiate orders, therefore, present this great distinguishing character, which more than any other detaches them from the others, namely, that every individual being furnished both with ovigerous and impregnating organs is sufficient to the impregnation of its own ova. Nothing, in truth, can be more simple than such an arrangement. The ovary is found, ■when empty, embedded in the substance of the liver, but at certain epochs it becomes so much distended with ova as to cover in great part the rest of the viscera ; from this ovary arises a simple canal or oviduct, which termi- nates after a short course in the neighbourhood of the anus. No trace of accessory apparatus has been found, and the only part to which the office of a testis is assignable is the tube through which the ova are discharged, which probably furnishes a secretion subservient to the impregnation of the eggs. Such is the structure of the generative system in Haliotis, Patella, and others of the orders to which these respectively belong, exhibiting a simpli- city of parts widely different from what is found in the division which next presents itself to our notice. The second type of the genera- tive apparatus is common to the Nudibran- chiute, Infer abranchiate, Tectibranchiate, and Inoperculated pulmonary orders ; in all of which every individual is provided with both male and female organs of copulation, and, accordingly, mutual impregnation is effected by the congress of two individuals, or in a few instances by the combination of several. We shall select the common snail ( Helix pomatia) as the most familiar illustration of the general arrangement of the parts composing this double apparatus, leaving the varieties which it presents to sub- sequent notice. The admirable plate of Cuvier, of which Jig. 190 is a copy, represents the whole system with that clearness and fidelity so characteristic of all the laborious contribu- tions to science which we owe to his indefati- gable industry. The female portion consists of the ovary, the oviduct, and an enlarged portion of the oviduct which forms a receptacle for the ova, and is called by Cuvier the womb (la matrice). The ovary (q) is a racemose mass embedded in that portion of the liver which is enclosed in the last spire of the body, i. e. that part which is placed nearest to the apex of the shell ; from this proceeds a slender oviduct (r), folded in zigzag curves, and vari- ously convoluted : it commences by many small branches derived from the ovary, and terminates in a mass (s), regarded by Cuvier as the testis, in which it becomes so attenuated that it is difficult to trace it ; emerging, how- ever, from this mass, it expands into the womb (t), which is a long, capacious, and sacculated canal, and capable of much dis- tension, in which the eggs are retained until they have acquired their full development : this viscus opens into the common generative cavity at e, Jig. 194. The male organs consist of a testicle, vas deferens, and penis. The testicle (s, Jig. 190) appears to be composed of two distinct portions, the larger of which is soft and homogeneous in texture, but the smaller has a granulated ap- pearance ; the latter (m) runs along the womb like a mesentery, connecting its folds as far as the termination of that viscus. The testicle varies much in size at different periods, being generally very small, but during the season of love it dilates so as to fill nearly half of the viscera] cavity, at which time the womb like- wise is much enlarged. From the testicle arises its vas deferens or excretory duct, which terminates in the penis near the base of that organ. The penis (fig. 194, n) is a most sin- gular instrument, resembling a long hollow whip-lash, formed of circular fibres, and, like the tentacles, capable of complete inversion, which in fact occurs whenever it is protruded from the body ; it is also furnished with a re- tractor muscle (Jig. 190, w ), serving to draw it back again after copulation is accomplished. The penis is not perforated at its extremity, but the vas deferens terminates within it by a small aperture, which of course during the inversion of the organ opens externally at about one-third of the length of the penis from its root ; the aperture by which the vas defe- rens thus opens upon the exterior of the penis, GASTEROPODA. 397 when that organ is protruded, is sufficiently distinct, admitting with facility an ordinary bristle (fig. 194, I). On slitting up the penis as it usually lies retracted into the visceral cavity, its inner membrane is found gathered into longitudinal folds, and this provision is needful to allow of that distension which must occur during its erection, at which time this lining membrane becomes the external integu- ment of the protruded organ. These parts would seem sufficient in them- selves to fulfil the functions belonging to the organs of both sexes, nevertheless we find others superadded, the uses of which are not so readily assignable ; these are the bladder, as it is called by Cuvier, the multifid vesicles, and the sac of the dart. The sac which has been called the bladder (fig. 190, z, fg. 194, o) is invariably present; it consists of a round vesicle, variable in size, communicating by means of a canal, generally of considerable length and diameter, with the termination of the matrix : it is usually found filled with a thick and viscid brownish matter, and is generally supposed to furnish an enve- lope to the eggs as they escape from the con- voluted oviduct, an opinion, however, as we shall afterwards see, which is not without op- ponents. The multifid vesicles (fig. 190, x, fig. 194, c ) are much less constantly met with, and are in fact almost peculiar to the snail ; they are two groups of cceca, each composed of about thirty blind tubes, which after uniting into larger canals ultimately form a principal duct on each side, through which the secretion which they furnish is poured at a little distance below the orifice leading to the bladder into the passage by which the ova are expelled. The fluid furnished by these curious glandular appendages is white and milky, but as this secretion is almost peculiar to the genus Helir, its use is extremely problematic. The sac if the dart (fig. 190, y, fig. 194, b) is another part of the generative apparatus only found in the snail, and from the extraordinary instrument which it conceals is perhaps the most singular appendage to the generative sys- tem met with in any class of animals. It is an oblong sac with strong muscular walls opening by a special aperture into the common generative cavity, like which it is capable of complete inversion. On opening it, its cavity is seen to be quadrangular, and at its bottom projects a four-sided fleshy tubercle, which secretes the curious weapon that this sac is destined to conceal. This (fig. 194, b ) con- sists of a four-sided calcareous and apparently crystalline spike, about five lines in length, which grows by successive layers deposited at its base from the surface of the fleshy tubercle to which it is attached : it will be evident that when the sac is everted, the dart contained within it will be protruded externally. This dart, if broken off from its place of attachment, is speedily renewed. To complete our description of the parts composing this complex organisation, it remains only to mention the common generative cavity Generative organs of Helix Pomatia. (fig. 194, a ), into which the others open ; this, when in its ordinary position, is a muscular bag, opening externally by a large aperture near the upper tentacle on the right side of the neck, whilst at its bottom are seen the orifices of three distinct passages, one leading to the penis, one to the female organs, and a third to the sac of the dart. This cavity, like that of the dart, is capable of inversion, which is effected partly by the action of its muscular walls, aided in all probability by a kind of temporary erection, and when thus turned in- side out, the orifices leading to the penis, the womb, and the sac of the dart of course become external. In order to understand the functions of these various parts it will be necessary to describe at length the singular mode in which copulation is effected. When two snails, amorously dis- posed, approach each other, they begin their blandishments by rubbing the surfaces of their bodies together, touching successively every part. This preliminary testimony of affection lasts for several hours, gradually exciting the animals to more effective demonstrations. At the end of this time the generative orifice, placed on the right side of the neck, is seen to dilate, and the common generative cavity becoming gradually inverted displays ex- ternally the three apertures which open into it. This being effected, an encounter of a truly unique character commences; the opening- leading to the sac of the dart next expands, and that organ undergoing a similar inversion displays the dart affixed to its bottom. A series of manoeuvres may then be witnessed of an unaccountable description ; each snail, in turn, inspired with an alacrity perfectly foreign to its ordinary sluggish movements, striving with his dart to prick the body of his associate, which with equal promptitude endeavours to 398 GASTEROPODA. avoid the wound, retreating into his shell, and performing a variety of evolutions to get out of reach. At length, however, the assailant suc- ceeds, and strikes the point of his weapon into the skin of his paramour at any vulnerable point which may be found. The dart is gene- rally broken off by this encounter, sometimes sticking in the skin, but more frequently dropping to the ground. The reptile Cupid having thus exhausted his quiver, becomes in turn the object of a similar attack, exhibiting apparently an equal anxiety to avoid the threat- ening point of the weapon bared against him. At last he receives the love-inspiring wound, and the preliminaries thus completed, each prepares for the completion of their embraces. The other two apertures next dilate, and from one of them issues the long and whip-like penis, unrolling itself like the finger of a glove ; this being fully developed is introduced into the vaginal orifice of the other snail, which in the same manner inserting its penis into the female aperture of the former, both mutually impreg- nate and are impregnated. See fig. 195. Fig. 195. It is difficult to conceive what can be the use of the dart so singularly employed ; it would seem to bean instrument for stimulating the sleeping energies of the creatures to a needful pitch of excitement ; yet why it should be peculiar to the snail is not obvious, for in the slug and other Mollusca certainly not less apathetic, no such structure has been detected. In Vaginulus (jig. 189) a similar arrange- ment of the principal organs is observable, although some modifications are met with which deserve our notice. No sac of the dart is found in this animal, but a fasciculus of cceca, analogous to the multifid vesicles as far as their structure is concerned, is connected, not with the female apparatus, as in the snail, hut with the male organs. The orifices of the two sexual systems are here separated by a considerable interval, the penis emerging at the side of the neck, near the right superior tentacle at z, while the orifice of the female parts is placed between the cuirass and the mantle, considerably further back. The ovary (m) is similar in structure to that of the snail ; and its duct, in like manner, forms many convolutions in the substance of the testicle (/>), from which it issues, much increased in size, to expand into a large membranous re- ceptacle (), resembling the corresponding part in the snail, and a thick muscular cavity, from which the former arises as a kind of appendage ; on opening the thicker portion its interior is seen to be rugose, and to enclose a small body, something like the caput gallinaginis in the human urethra. The multijid vesicles (y) open near the exterior orifice, through which the whole apparatus, by a process of inversion already described, is protruded so as to form the male organ of ex- citement. In many of the Tectibranchiata a remark- able arrangement of the generative organs is found, as the male viscera are divided into two distinct portions, the exciting organ being at one extremity of the body, while the testis is found connected with the female apparatus in a distant part of the system. This will be seen in Doridium Meckelii (fig- 196); the penis (/), seen retracted in the figure, issues from the side of the neck, and has appended to its root a zig-zag tube, inclosed in a mem- branous canal, the nature of which is un- known. Quite detached from these, and placed near the anus, we have the matrix ( f), the testis (g), and the bladder (i), occupying their usual relative position as regards each other, and terminating in the vulva or sac of generation (//). In Aplysia the organ of excitement is found GASTEROPODA. 399 Fig. 196. near the right tentacle, where it protrudes, as in the Snail, for the purpose of copulation, by the inversion of its walls; it is, however, absolutely imperforate, and receives no duct by which it can communicate with the testis so as to become instrumental in immission; but externally a deep groove is seen upon its surface when in a state of protrusion, which is continuous with a long furrow seen upon the surface of the body, continued from the base of the penis to the orifice of the female ap- paratus. Fig. 197 represents the secreting Fig. 197. Generative organs of Aplysiu. portions of this system removed from the body, and displayed so as to expose the internal structure of the parts composing it. The ovary (ft) is a large oval, whitish, and granular mass, from which the oviduct arises by several distinct tubes which emerge from different parts of its substance : this oviduct opens into the common tube (e), which may be called the vagina. The mass (J] g), called by Cuvier the testis, and supposed by him to be solid and homogeneous in its texture, is found, when opened, to he divided by spiral septa, resem- bling the scala cochleae in the ears of Mam- malia (g), and thus forms a long spiral cavity communicating with the commencement of the vagina, in which latter tube we also find aper- tures by which the vesicle ( p) and the larger sacculus (o) communicate with the common passage. In Onchidium, an aquatic species belonging to the inoperculate pulmonary order, the male and female parts are in a similar manner placed at opposite extremities of the body, but the former assume a more complicated structure than in the Tectibranchiata, which we have described. The ovary (Jig. 198, a, a, a) Fig. 198. Generative organs of Onchidium. consists of two masses replete with ova, each of which furnishes a short duct ; the two thus formed unite into a convoluted tube (b), which is the common oviduct : arriving at the mass always regarded by Cuvier as the testis, it enlarges and forms within the substance of that organ many convolutions, on emerging from which it runs directly in the shape of a narrow canal (rf), to the external orifice (h). The bladder (j) receives a large duct (e) from the mass here assumed to be the testis, and gives off another of equal size, which joins the Oviduct (rf) prior to its termination. This 40Q GASTEROPODA. would seem to form a complete system in itself ; yet, on examining the male organ of excitement, we find it connected with considerable appendages, the nature of which it is difficult to conjecture. The sac (m) is muscular, and resembles the mus- cular root of the penis in the genera already described, being, as in them, capable of in- version : at its base are seen two cul-de-sacs, into each of which opens a long and flexuous canal (/, ?;). The canal marked n is very slender, and when unfolded is four times the length of the body of the animal ; its termi- nation at the point most remote from the mus- cular sac into which it opens is apparently closed. The other tube marked / is much wider and of extraordinary length; its com- mencement (t) is extremely convoluted and fully eight times as long as the body ; its walls are thin, but it is supplied plentifully with blood by means of a large artery interlaced with its convolutions ; at k it becomes enveloped in a fleshy mass of considerable thickness, after which, assuming its original appearance, it proceeds to the cul-de-sac, at the bottom of which it terminates. In Jig. b, 1 98, the muscular cavity (m) has been laid open, and the mode in which the above tubes enter it has been displayed ; the smaller one(n) ends in a little horny papilla (q) seen in the engraving ; the larger tube (7) terminates by a kind of glans penis, perforated by a large aperture and sur- rounded by a kind of prepuce (p) : on open- ing the vessel a little before its entrance into the muscular sac, it is found to conceal a sharp horny dart (o), supported upon a fleshy pedicle, and readily protrusible through the aperture p; the analogy between this singular instrument and the dart of the Snail is ob- vious, for when the muscular sac («) is everted, the papilla; (p, q) become external, and the horny point being pushed out of the former will probably form a stimulus of the same description. We have hitherto abstained entirely from mixing up with our description of these prin- cipal forms which the generative system of the mutually impregnating Gasteropoda presents, the discussions which have arisen concerning the real nature of the different organs which have been described, and have designated them by the terms usually applied to the respective parts,without reference to their individual func- tions. It now, however, becomes necessary to lay before our readers the principal opinions which are recorded upon this subject. The chief points of debate have been the bladder, and the on;an which we have described under the appellation of testicle. The bladder is, from its constant occurrence, evidently an organ of some essential use: it was regarded by Swammerdam as the secreting structure from which the colouring fluid peculiar to some species is produced, especially in the Murices and others of the marine genera ; it was there- fore named by him sac of the purple; but we shall afterwards find that this fluid is derived from another source. Blainville, on the other hand, considers this vesicle as analogous to the urinary bladder of Vertebrata ; in reference to this hypothesis, however, we should be inclined to ask, with Cuvier, where are the kidneys ? and even upon the supposition that the secretion of the bladder itself was analogous to the urinary fluid, we are not aware of any chemical proofs of its nature which are sufficient to establish the identity. Delle Chiaje again sustains that the sac of the purple is, in fact, the testis, and that its secretion, poured as it constantly is into the termination of the oviduct, is in re- ality the fecundating fluid ; yet against this we must urge the distribution of the vas deferens met with in the Helices, which from its entire arrangement converts the organ of excitement in these animals into an apparatus of immis- sion, whose nature cannot be mistaken. The opinion which we consider most consonant with all the circumstances of its position, is that it is a reservoir for the seminal fluid analogous to the spermotheca of certain insects. Cuvier expressly notices the constant relation which exists between the length of the penis and that of the canal which leads to this sac- culus, and when we remark the long chains of ova which are slowly extruded in most of the Gasteropoda, we are readily disposed to admit of the necessity of such a reservoir, which, treasuring up the semen until the eggs are about to be expelled, applies it efficiently to the ova as they successively pass the orifice of its duct. This supposition derives additional weight from what we have found to be the arrangement of the seminal ducts in Vaginulus and Onchidium. In the former we observed that, besides the canal, which, as in the Snail, perforates the root of the penis and thus be- comes subservient to copulation, the vas de- ferens actually pours a part of its contents by a separate canal into the bladder itself, which, as in all cases, communicates with the egg- passage. In Onchidium the connexion be- tween the testis and this receptacle is equally striking, as will be obvious on reference to the drawing given above. In Aplysia, Delle Chiaje considers the testicle as described by Cuvier to be in reality the matrix or receptacle for the ova, in which they attain their full development prior to expulsion, basing his opinion upon the disposition of the spiral cavity which it contains. We are entirely left to conjecture as to the uses of the other appendages found in par- ticular species, and the multifid vesicles of the Snail, which are wanting even in the Slug, the tortuous canal connected with the penis of Doridium, and the still more singular organs belonging to the male apparatus of Onchidium, must still remain the subjects of observation and experiment. The third form of the generative system in which the sexes are distinct, is met with in all the Pectinibranchiate order, and in the operculated Pulmonalia of Ferussac. In Buc- cinum, which we shall select as an example of the general arrangement of the sexual organs in the former, the male is at once distinguish- GASTEROPODA. 401 Fig. 199. Male organs of Buccirium. able by the enormous penis attached to the right side of the neck (jig. 199), which is not, as in the last division, capable of retraction within the body, but remains permanently ex- ternal, being, when not in use, folded back and lodged within the branchial cavity, from which however it is frequently protruded without any apparent object. In the female there is no rudiment of such a structure, but the generative aperture is seen to be situated a little within the edge of the pulmonary cavity, being a simple hole leading to the oviduct. The internal organs of the male, represented in the annexed figure, con- sist simply of a testicle and its excretory canal. The testis is of considerable size, sharing with the liver the smaller convolutions of the shell ; from this arises the vas deferens, which forms by its convolutions a kind of epididymis (Jig. 199, b), and then increasing in diameter enters the root of the penis, through which it passes by a tortuous course (d) to the tubercle at the extremity of this organ, where it opens externally. The penis when opened, as re- presented in the engraving, is seen to contain strong transverse fasciculi of muscle, which probably cause the erection of this organ ; they will at the same time lengthen it, so as to destroy in a great measure the zig-zag turns into which the vas deferens is thrown in its usual relaxed state. In the female the position of the testicle is occupied by the ovary, while the vas deferens is represented by a thick and glandular oviduct. In Mures the penis of the male is pro- portionally smaller; and, instead of a com- plete vas deferens, penetrating to its extremity, there is merely a groove along its surface, along which the semen flows. In Voluta the ex- terior groove only runs to the base of the penis, and in Strombus the male organ is a mere tubercle. In the Pulmonalia operculaia the organs of both sexes are in every respect similar to those of the Pectin ibranchiale order. In Valudina alone ( Helix vivipara, Lin.) the penis is retrac- til e, issuing from ahole found in the right tentacle, and from the disparity in size between the tentacles, arising from this cause, the male is readily distinguished. The females of this genus are not unfrequently ovo-viviparous, the ova remaining in their capacious oviduct until they are hatched. Spallanzani asserts that, if the young of Paludina are taken at the moment of their birth, and kept entirely separate from others of their species, they can reproduce without im- pregnation, like the Aphides and Monoculi, in which the same connexion with the male is found to fecundate not only the female herself, but her offspring for several generations. Nevertheless, whether Spallanzani's observa- tions be correct or not, the males are fully as numerous as the females, so that it would be difficult to imagine the object of such a de- viation from the ordinary proceedings of na- ture. Ova. — The spawn of the Gasteropod Mol- lusca is found under diverse forms ; it is usually in the marine species attached to the surface of stones, shells, or sea-weed, the ova being connected with each other in long ri- bands or delicate festoons, which are some- times extremely beautiful and curious. The Doris and Tritonia deposit their ova in this manner, and the mass of eggs deposited by them resembles a frill of lace of extreme beauty. In Aplysia the spawn is found to resemble long gelatinous threads, in the centre of which the ova are seen, varying in tint, so as to give different colours to different parts of the thread; the whole strikingly resembles strings of vermicelli, and the Italians in fact have applied to them the name of vermicelli murini. In Helix and Bulimus the eggs are naked and protected by a hard shell, whilst in Buccinum, Voluta, Murex, and other marine species, the ova are enveloped in membranous sacs agglomerated together in large bunches ; these sacs have been erroneously regarded as the eggs themselves; they are, however, merely coriaceous envelopes, answering the purpose of the gelatinous coating enclosing the eggs of other species, several eggs being contained in each bag, in which, when mature, the young are easily seen. It would seem that extraordinary provisions have been made by nature for the multiplication of these creatures, in spite of the numerous enemies which devour them, or the vicissitudes of temperature to which, espe- cially in the terrestrial species, their eggs are necessarily subject. We are indebted to M. Leuchs for several interesting observations concerning the ova of slugs, which explain in a great degree the quantities of them which in some seasons infest gardens and vineyards, becoming, from the devastation which they cause, serious plagues to the agriculturist. The number of eggs varies with the healthiness of the animal, the supply of food, or the tem- perature of the season ; yet it is probable that a single slug will lay five hundred, under ordinary circumstances : thus, supposing a thousand of these creatures to be collected in 402 GASTEROPODA. a given space, they will give birth in a few weeks to five hundred thousand young slugs, which multiplying in their turn would pro- duce at the second laying two hundred and fifty millions of eggs. This fact is well worth the notice of the farmer, who, instead of dri- ving away with so much assiduity crows and other birds which live upon these destructive, though apparently insignificant, animals, would do well occasionally to cherish them as fellow- labourers in his grounds. The Terrestrial Mol- lusca, helpless and incapable of defence, afford food to numberless indefatigable assail- ants, and their preservation is provided for, not only by the number of their eggs, but by a peculiar tenacity of vitality which these ex- hibit under circumstances which would be thought sufficient to destroy the young before they were hatched. The skin of the eggs of the slug is coriaceous and very elastic, so that when compressed they soon resume their shape : exposure to intense cold does not de- stroy their fertility, and they have been known to resist a temperature of 40° without ap- parent injury. When dried by artificial heat, they shrivel up to minute points only distin- guishable by the microscope, yet in this state, if they be put into water, they readily absorb it and are restored to their former plumpness. The same thing happens to those which are dried by the action of the sun and apparently destroyed; a shower of rain is sufficient to supply them with the fluid which they had lost and to restore their fertility. This drying ap- pears not to injure them. M. Leuchs found that after being eight times treated in this manner, they were hatched on being placed in favourable circumstances, and even eggs in which the embryo was distinctly formed, sur- vived such treatment without damage. Reproduction of' lost parts. — Not less won- derful is the power which snails possess of repro- ducing lost parts, after mutilation by accident or design. The results of the experiments of Spallanzani upon this subject are very curious ; he found that if the large tentacle of a snail were amputated, the extremity of the stump heals, forming a small swelling of a lighter colour than the rest of the horn ; in this swel- ling a black point soon becomes visible, which is a new eye, and the mutilated member, in- creasing in length, shortly equals its original size, although it is for some time of a lighter colour than its uninjured fellow, which in other respects it perfectly resembles. The process sometimes varies a little ; it frequently happens that the end of the stump, instead of becom- ing round, is elongated and tapers to a point, from the apex of which the new eye is seen to " squeeze out ;" the end of the tentacle then assumes a globular shape, and the most accu- rate dissection cannot distinguish the newly formed eye from the original. If, instead of the horn, the head is cut quite off, a new one will succeed : the new head, however, does not at first contain all the parts of the old one, but they are gradually developed, piece by piece, at different intervals, until at length a head differing little, if at all, from the original pattern is completed. In some cases the ob- ject is effected by a different proceeding, the new part appearing like a round tubercle, con- taining the rudiments of the lips and of the smaller horns, which is united to the mouth and the new-formed tooth, the other parts, as the larger horns and the anterior part of the foot, being totally deficient. In another snail the larger tentacle on the right side first ap- peared, not more than one-tenth of an inch in length, but already provided with its eye, and at a short distance beneath this the linea- ments of the lips separately developed them- selves. In a third snail a group of three horns is seen, two of which will acquire their full developement, while the third is just above the level of the skin. These and many other varieties have been observed ; but in most instances there is no perceptible difference between the new head and the one cut off, the exact line of separation being indicated by an ash-coloured mark distinguishable two years after the experiment. The same effects follow, whether the head be removed above or below the brain, and in the latter case a new brain, with all its nerves, is speedily con- structed. The collar and foot are also per- fectly restored after their removal. Slugs reproduce their horns as well as snails, but their power of manufacturing a new head is much inferior. Muscular integument. — None of the Gaste- ropoda have any thing analogous to an endo- skeleton, a circumstance which sufficiently ac- counts for the varied forms which the same in- dividual assumes under different circumstances, for the body being unsupported by any re- sisting framework, readily yields to the con- tractions of the muscular integument with which it is covered. It is from this circum- stance that the zoologist finds the preservation of the natural forms of the recent animals a task of such extreme difficulty, owing to the corrugation and distortion produced by the or- dinary modes of preservation ; it is scarcely possible indeed, in many cases, to recognise with tolerable accuracy the natural appearance of these creatures in the shrunken specimens generally preserved in our cabinets, and the collector of these objects would do well never to omit, when circumstances allow him the op- portunity, to preserve some sketch of the living forms of such exotic species as may come into his possession. Body. — In the naked Gasteropods the whole body is found to be inclosed in a muscular in- tegument, the basis of which is a cellular web of extraordinarily extensible character, in which the muscular fibres may be seen to cross each other in various directions, some passing longi- tudinally from one extremity of the animal to- wards the opposite end, while others, assuming different degrees of obliquity, are interwoven with the rest, so as to occasion the elongation or contraction of the body in every assignable direction. Within this muscular bag the vis- cera are contained, as well as the organs sub- GASTEROPODA. 403 servient to mastication, the apparatus of the external senses, and of the organs employed in copulation, which are, when unemployed, re- tracted within its cavity by special muscular fasciculi spoken of elsewhere. Retractile muscles. — In the spirivalve genera the muscular walls which inclose the body only exist in such parts as, during the extended state of the animal, are protruded from the shell ; that part of the body which is concealed within its cavity being provided with a much more delicate and membranous envelope ; in such, however, a necessity exists for an additional muscular apparatus, serving to retract the body and foot within the cavity of its calcareous abode, and of course exhibiting various modifi- cations of arrangement in conformity with the shape of the shell itself. In the turbinated shells, the retracting muscles consist of strong fasciculi of fibres arising from the columella or axis of the shell, and diverging from this point, spread in several slips, which become interlaced with the fibres composing the foot and muscular investment. In the flattened forms of Patella and Chiton, the muscular fibres arise all around the margin of the shell, excepting at its anterior part; these penetrating the mantle are intimately interwoven with the muscles forming the circumference of the foot. The animal of the Haliotis is fixed to its ex- panded and semi-turbinated shell by a single large and ovoid muscle, which takes its origin from near the middle of the last spire ; what- ever the disposition of these muscles, however, their action is obviously of two kinds ; and not only are they the agents by which the creature retires within its covering, but by raising the central portion of the disc of the foot, whilst its margins are in apposition with the plane of progression, they will, by producing a vacuum beneath, convert the whole apparatus into a sucker, the adhesive power of which will be proportioned to the extent of its surface. Foot. — The foot of the Gasteropoda is their principal agent of progression. It is generally a fleshy disc, of variable size and shape, attached to the ventral surface, and forming when ex- panded an organ by means of which the animal can adhere to surrounding objects. In the naked genera it is small, but in the conchife- rous species, especially in such as are provided with dense and weighty shells, its dimensions and force are proportionally increased. In its internal structure it resembles the muscular in- vestment of the body, of which in fact it is merely an expansion, consisting of muscular fibres interlacing each other in every possible direction, as may be developed by continued maceration. In the Slug, when opened from the back, the superior layer of fibres is found to run transversely, arising apparently from two tendinous lines which run longitudinally near the centre of the organ, and terminating near the margins of the disc ; beneath these, longi- tudinal fasciculi may be detected, but so inter- laced with other fibres assuming every degree of obliquity, that it is impossible to unravel the complicated structure which they form. In the Limpet (Patella) the lower fibres of the foot are transverse, but near the circumference they become distinctly interwoven with circular fas- ciculi ; the superior stratum viewed from above consists of two series of oblique fibres, which meet at an acute angle on the middle line, whilst the substance of the organ is composed of muscular bands variously disposed : from such a structure the movements of the foot are readily understood ; the transverse fibres by their contraction will elongate the ellipsis of the foot by diminishing its breadth, whilst the longitudinal, having a contrary action, will, by the combination of their effects, produce every movement needful for the progression of the creature. On minutely inspecting the foot of a terrestrial Gasteropod, as it crawls upon a transparent surface, it will be found to be divided into a certain number of transverse seg- ments of variable size by a particular arrange- ment of the longitudinal muscular fibres, which seem to form, when the creature advances, un- dulations limited by the points of contact. These sections appear alternately to form a vacuum upon the surface where the animal is placed, that which follows advancing to take the place of that which precedes it, the trans- mission of movement occurring from behind forwards, a mechanism which causes the animal to advance by a slow and uniform progression. The above structure of the foot, and conse- quent mode of locomotion, although the most usual, is susceptible of considerable modifica- tion. Thus in Sci/llaa, we find it only adapted for grasping the thin stems of fuci and other submarine plants, being for that purpose com- pressed and grooved inferiorly into a deep sul- cus. In the Tornatella fusciata, Lam. the struc- ture of the foot is remarkable : beaten incessantly by the waves, in the cavities of rocks which it frequents, nearly on a level with the surface of the sea, to the violence of which it is always exposed, it has need of additional powers of retaining its hold ; its foot is therefore divided into two adhering portions, placed at each extremity, and separated by a wide interval ; when it crawls it fixes the posterior disc and advances the other, which it attaches firmly to the plane of progression, and this being effected, the hinder sucker is detached and drawn for- wards, locomotion being accomplished by the alternate adhesion of these two prehensile discs. In Cyclostorna the foot is likewise furnished with two longitudinal adhering lobes, which are advanced alternately. But the foot is not merely an instrument of progression on a solid surface, in many species being convertible, at the will of the animal, into a boat, by means of which the creature can suspend itself in an in- verted position at the surface of the water, where by the aid of its mantle and tentacles, it can row itself from place to place. The Buli- mus stagnalis, so common in our pools of fresh water, is a good example of this mode of sail- ing ; and in the marine species, Aplysia and Gastropteron may be enumerated as exhibiting a similar structure. Some of the naked Gasteropods, as Aplysia and Thethys, are able to move through the water in the same manner as the leech by an 404 GELATIN. undulatory movement of the whole body, a mode of progression which in Thethys is mate- rially assisted by the membranous expansion of the mantle placed around the anterior part of the body, which forms a broad veil, and from the muscular fibres contained within it, must necessarily be an important agent in swim- ming. Particular secretions. — Many of the Gaste- ropoda, in addition to the secretions which have been mentioned, furnish others adapted to peculiar circumstances, and produced from special organs. In the Snail and the Slug tribes a slimy mucus is furnished in great abundance from an organ which has been denominated the " sac of the viscosity ;" this is a membranous bag sur- rounding the pericardium, which when opened is found to be divided internally by delicate septa arising from its walls ; from this proceeds a capacious duct, which follows the course of the rectum, to which it is intimately united, to open externally in the neighbourhood of the respiratory aperture. The viscid secretion of this gland spreading over the surface of the foot is most probably an assistant in progres- sion, causing it to adhere more intimately to the surfaces over which the animal crawls. Aplysia furnishes three distinct fluids issuing from different parts of the body. The first is a glairy mucus, which exudes in considerable quantities from the surface of the mantle, espe- cially when the creature is irritated. The se- cond i- a whitish liquor, which is thick and acrid, and has been reputed venomous; it is emitted in very small quantities, but its smell is strong and highly nauseous: the gland which produces it is a little reniform mass placed near the vulva, close to which is the orifice of its excretory canal. Blainville looks upon this as the representative of a urinary apparatus, but it does not appear to exist in all the species, and is never emitted except when the animal is tor- mented. The third secretion is much more abundant than the other two, and is generally of a beau- tiful lake colour, except in Aplysia citrina, in which it is yellow. It is contained in a spongy substance, which occupies all those portions of the little mantle or operculum to which the shell does not extend. All the areolae of this tissue are filled with a purple matter, the colour of which is so intense, that when it is expressed it has a black violet hue, but when mixed with a large quantity of water, imparts to it the co- lour of port wine. This colouring fluid seems to exude through the skin of the mantle, no ex- cretory duct having been found specially ap- propriated to its escape : it is apparently pro- duced from a triangular glandular mass situated in the base of the mantle. Several speeies of Murex secrete a similar fluid, which, like the ink of the cuttle-fish, serves as a defence from attack ; in all cases it is expelled with force, and in such abundance as to colour the water around to a considerable distance. There is a species of Limax, (Limax nocti- lucus, ) described by M. Orbigny,which produces a phosphorescent secretion capable of emitting a light of considerable brilliancy. The luminous organ is a small disc of a greenish colour by day-light, soft in texture, and slightly contractile. The light is only visible when the creature is expanded and in motion. The disc is always covered with a greenish mucus, which, if wiped off, is speedily renewed. It is found to be connected with the generative organs, and ap- pears to be principally useful during the season of love. BIBLIOGRAPHY. — Swammerdam, Biblia Naturae seu Historia Jnsectorum, t'ol. 1737. Cuvier, G. Lecon9 d'Anatomie Comparee, 8vo. 1799. Ibid. Memoires pour servir a l'Histoire et I'Anatomie des Mollusques, 4to. 1817. Be Blainville, de l'Orga- nization des Animaux, on Principes d'Anatomie Comparee, 8vo. 1822. Belle Chiaje, Memorie sulla storia e notomia degli animali senza vertebre del Regno di Napoli, Ferussac, Histoire des Mollus- ques terrestres et fluviatiles, fol. Spallanxani, Opuscoli di Fisica animale e vegetabile, 1776. Reaumur, De la formation ct de l'accroisse- ment des coquilles des animaux tant terrestres qu'aquatiques, in the Memoires de l'Acad. des Sciences, 1709. He continued the subject in the same work for 1716, under the title of Eclaircisse- mens des quelques difficultes sur la formation et l'accroissement des coquilles. Hatchett, on the chemical Composition of Shells, Phil. Trans. 1799- 1800. Beaudant, Memoire sur la structure des parties solides des Mollusques, Annales du Museum, torn. xvi. p. 66. Weiss, M. Sur la progression des Gasteropodes Terrestres, Journ. de Physique de Rozier, An. i. p. 410. Lamarck, Systeme des Ani- maux sans Vertebras, 7 vol. 8vo. 1815-1822. Har- derus, Examen Anatomicum cochlear terrestris do- miportse, Basileas, 1679. ( T. Ri/mer Jones.) GELATIN (Fr. gelatine; Germ. Leim. Gallerte ). This term is applied to an im- portant principle obtained by boiling certain animal substances in water, and filtering or straining the solution, which, if sufficiently concentrated, gelatinises, or concretes into a translucent tremulous mass on cooling, which may be again liquefied and gelatinised by heat and cold. Many varieties of gelatin occur in commerce, of which glue is perhaps the most important : it is obtained by boiling the refuse pieces of skin and hide, and the scrapings and clippings from the tan-yard, in a sufficient quantity of water, till a sample taken out of the boiler forms, on cooling, a stiff jel ly ; the solution is then strained whilst hot, and run into coolers, where it concretes, and is afterwards cut by a wire into slices, which are dried upon nets. Membranes, tendons, cartilage, horn-shavings, and other similar sub- stances also yield a jelly, which, however, is less stiff and binding than the former, espe- cially when obtained from young animals : size is a jelly of this description. Isinglass, which consists of several parts of the entrails of fish, and especially the sound, &c. of the sturgeon, yields a very pure and tasteless jelly, which is chiefly used for the table ; the jelly of calves' feet and hartshorn-shavings is some- what similar. As jelly cannot be extracted by cold water, and as we have no direct evidence of its existence in the various substances from which GELATIN. 405 it is obtained previous to the action of boiling water, and, moreover, as it does not occur in any of the animal fluids or secretions, it has been regarded by some chemists, and especially by Berzelius, as a product of the action of water and heat, and not as a mere educt. He compares its formation to the conversion of starch into gum and sugar, and remarks that in both cases the change is ac- celerated by the presence of dilute acids. Pure gelatin is colourless, transparent, in- odorous, insipid, and neither acid nor alkaline ; heat softens it and exhales a peculiar odour, and it burns with smoke and flame, leaving a bulky coal, difficult of incineration and containing phosphate of lime : it yields much ammonia, and the other ordinary products of analogous animal compounds, when subjected to destructive distillation. In cold water dry gelatin swells and be- comes opaque, and when gently heated it dissolves and forms a clear colourless solution, which gelatinises when cold. According to Dr. Bostock, one part of isinglass to 100 parts of water yields a perfect jelly, but with 180 of water it does not concrete.* Those modifications of gelatin which are the least soluble in hot water yield the strongest jelly. When the same portion of jelly is repeatedly liquefied and cooled, it gradually loses the property of gelatinising, and becomes so far modified as to leave a brownish gummy residue when evaporated, which readily dissolves in cold water. L. Gmelin kept a solution of isinglass in a sealed tube for several weeks at the temperature of 212° : it was thus changed to the consistency of turpentine, was deliquescent, soluble in cold water, and par- tially so in alcohol. An aqueous solution of gelatin exposed for some time to the air at the temperature of 60° to 70° becomes at first thinner and sour, and afterwards ammoniacal and fetid : the addition of acetic acid prevents the putrefac- tion without impairing the adhesive power of the gelatin. Gelatin is insoluble in alcohol and ether, and in the fixed and volatile oils. When a strong aqueous solution of gelatin is dropped into alcohol, it forms a white adhesive and elastic mass, which adheres strongly to the glass, and which, like dry gelatin, softens, but does not dissolve in cold water. When chlorine is passed through a warm and somewhat concentrated solution of gelatin, each bubble becomes covered with an elastic film, and deposits, on bursting, a white, tough viscid matter; the whole of the gelatin is thus precipitated, and free muriatic acid is formed. This chloride of gelatin is insoluble in water and alcohol, and remains acid, and smells of chlorine, even after it has been kneaded in warm water. Dissolved in caustic am- monia in a tube over mercury, it evolves nitrogen and becomes mucilaginous. It is soluble in acetic acid; but the solution, though rendered turbid by dilution, gives no preci- * Nicholson's Journal, xi. 244. pitate by ferro-cyanuret of potassium, so that the gelatin is not thus converted into albumen, No analogous compound is produced either by iodine or bromine. The action of sulphuric acid on gelatin has been studied by Braconnot.* When one part of glue and two of sulphuric acid are mixed, they form in twenty-four hours a clear fluid, which, when diluted with eight parts of water, boiled for eight hours, (the loss by evaporation being replaced by fresh portions of water,) and then neutralised by chalk, filtered, evaporated to the consistency of syrup, and set aside for a month, yields a crystalline crust of a peculiar saccharine substance, which is insoluble in alcohol and ether, unsusceptible of vinous fermentation, and gives ammonia by destructive distillation. It combines and forms a peculiar crystallisable compound with nitric acid, which he calls the nitro-saccharic acid, and which combines with the salifiable bases and forms distinct salts, the Droperties of which closely resemble the carbuzotates. Dilute nitric acid dissolves gelatin without the evolution of nitrous gas, and forms a yellow solution, which, by evaporation, (or the ad- dition of an alkali,) becomes darker, and at last evolves nitrous gas, and passes (often with ignition) into a spongy coal.f By concen- trated nitric acid gelatin is converted into malic and oxalic acids, a fatly substance, and artificial tan. J Acetic acid dissolves gelatin and the solution does not gelatinise, but upon drying, the ad- hesive power of the gelatin is unimpaired : the dilute acids do not generally prevent ge- latinisation. Neither the dilute caustic alkalis nor am- monia prevent the concretion of a solution of gelatin, but they render- it turbid by precipi- tating its phosphate of lime. Gelatin is soluble in strong caustic potash, with the exception of a residue of phosphate of lime. The solu- tion, when neutralised by acetic acid, does not gelatinise, and yields on evaporation a compound of gelatine with acetate of potash, which is soluble in alcohol. Sulphuric acid precipitates sulphate of potash from this acetic solution, in combination with gelatin ; and this compound precipitate, dissolved in water, crystallizes by spontaneous evaporation to the last drop.§ Hydrate of lime does not affect a solution of gelatin, but much lime is dissolved by it: it also takes up a considerable quantity of recently precipitated phosphate of lime. Gelatin is not precipitated by solution of alum, but when an alkali is added the alurnine falls in combination with gelatin. The alu- minous solution of gelatin is used for sizing paper, and for communicating to woollen cloth a certain degree of impenetrability to water. The acetates of lead do not precipitate pure gelatin; by corrosive sublimate its solution is * Annalcs de Chim. et Pliys. xiii. t Hatchett, Phil. Trans. 1800, p. 369. t Ibid. § Berzelius. 406 ORGANS OF GENERATION. rendered at first turbid, and when excess is added a white adhesive compound falls: nitrate and per-nitrate of mercury and chloride of tin occasion nearly similar changes. But the me- tallic salt which is the most decided precipitant of gelatin, and which does not affect albumen, is sulphate of platinum ; it throws it down even from very dilute solutions, in the form of brown flocculi, which, when collected and dried, become black and brittle, and which, according to Mr. Edmund Davy, to whom we owe this effective test, consist of about 76 per cent, of sulphate of platinum and 24 per cent, of gelatin and water. We now come to the most important and characteristic property of gelatin, which is, that of combining with tannin, and upon which the art of tanning, or the conversion of skin into leather, essentially depends, for the true skin ( cutis ) of animals consists of a condensed and fibrous form of organised gelatin, and, when properly prepared and im- mersed in a solution of vegetable astringent matter or tannin, it becomes gradually pene- trated by and combined with it, and when dried is rendered insoluble and durable. The tannin of the gall-nut is perhaps that which forms the most insoluble precipitate in gelati- nous solutions, and is therefore the most de- licate test of the presence of gelatin ; but, as albumen is also thrown down by it, the absence of the latter must have been previously ascer- tained. (See Albumen.) A strong infusion of galls occasions a precipitate in water holding less than a five-thousandth part of gelatin in solution, and, if added to a strong solution of gelatin, it throws it down in the form of a curdy precipitate, more or less dense and coloured according to the greater or less excess of the precipitant. The precipitated compound is insoluble in water, dilute acids, and alcohol, and when dried becomes hard and brittle, but again softens and acquires its former appear- ance when soaked in water : it may be termed tanno-gelatin. When tannin is added to a solution of gelatin, the latter being in excess, and especially if it be warm, no precipitate is immediately formed, for tanno-gelatin, when recently precipitated, is to a certain extent soluble in liquid gelatin. Tanno-gelatin does not appear to be a definite compound ; at least it is difficult to obtain it as such : the preci- pitate by infusion of galls consists, when care- fully dried, of about 40 per cent, of tan and 60 of gelatin. When obtained by other astringents, such as oak-bark, catechu, and kino, it differs in the relative proportion of its components and in its other characters, and often contains extractive matter. According to Sir H.Davy,* 100 parts of calf-skin thoroughly tanned by infusion of galls increase in weight 64 parts ; by strong infusion of oak-bark 34, and by weak 17; by concentrated infusion of willow- bark 34, and by dilute 15 ; and by infusion of catechu 19. Mr. Hatchett's researches have shewn that gelatin is also precipitated by the varieties * Philos. Trans. of artificial tan, and that the compound thrown down resembles in its leading characters the tanno-gelatin of natural tan. The ultimate composition of gelatin (pure isinglass) has been quantitatively determined by Gay Lussac and Thenard, with the following results : — Nitrogen Carbon Oxygen Atoms. Equiv. Theory. Experiment. . 1 14 16.09 16.998 . 7 42 48.28 47.881 . 7 7 8.04 7.914 . 3 24 27.59 27.207 1 87 100.00 100.000 As the combining proportion of gelatin has not been accurately ascertained, its equivalent number, as above given, is open to doubt, but it is probably correct, and the theoretical and experimental results closely correspond. ( W. T. Brandt.) GENERATION, ORGANS OF, (Com- parative Anatomy). — Few subjects connected with physiology have been investigated more assiduously than that of the generation of ani- mals ; and in none, perhaps, has the poverty of our knowledge of the operations of nature been more conspicuously exemplified. In studying many functions of the animal economy, the laws of chemistry and mechanics have been suc- cessfully appealed to by the philosopher, and their application to the operations of the animal frame satisfactorily substantiated ; but in at- tempting to explain the wonderful process by which organized bodies are perpetuated, all the resources of modern science have been found totally inadequate to the task, and we are still left to record facts and observations concerning the structure of the organs appropriated to the propagation of animals, without being in any degree able to connect them with the results so continually offered to our contemplation. In taking a general survey of the animal kingdom, we are at once struck with the infinite variety of forms which it presents, adapted to an end- less diversity of circumstances, and might expect to meet with a corresponding dissimilarity in the organization of the generative apparatus pecu- liar to each : no such dissimilarity, however, exists in nature, the modes of reproduction conform to a few grand types, and the increasing complexity of parts, apparent as we ascend to higher classes, which it will be our business to trace in this article, will be seen to depend rather upon modifications in the arrangement of secondary structures than upon any deviation from the fundamental organization of the more immediate agents. Without entering upon any discussion con- cerning the theories which have from time to time been advocated relative to spontaneous generation, we shall divide all animals as re- lates to the generative function into three great classes, grouping together such as are 1st. Fissiparous, in which the propagation of the species is effected by the spontaneous divi- sion of one individual into two or more, pre- cisely resembling the original being. ORGANS OF GENERATION. 407 2nd. Gemmiparous, in which the young sprout as it were from the substance of the parent. 3rd. Oviparous, producing their offspring from ova or germs developed in special organs adapted to their formation. Of these modes of reproduction the two first are confined to the lowest or acrite division of the animal kingdom, whilst the third or ovipa- r?Uo type is common to all other classes. Fissiparous generation is the simplest possi- ble, and presupposes a corresponding simpli- city of structure in the animals which propa- gate in this manner. It is principally confined to the Polygastric animalcules, most of which are multiplied by the spontaneous separation of an individual into two portions precisely resem- bling each other, and capable of performing all the functions which originally belonged to the undivided creature. Some of the larger species of Trichoda are well calculated to exhibit to the microscopic observer the steps by which this process is accomplished : the animalcule, prior to its division, is seen to become slightly elongated, and a tiansparent line is gradually distinguishable, indicating the course of the in- tended fissure ; at each extremity of this line a contraction of the body is speedily observable, and the lateral indentations become deeper and deeper, till at length a perfect separation is effected. The direction in which this divi- sion occurs is not always the same even in the same species ; thus, instead of traversing the shorter axis of the body it not unfrequently assumes a longitudinal or oblique direction, and from this cause it is not unusual to find the newly divided creatures differing materially in appearance from their adult or rather conjoined form ; for in this process the old animalcules literally become converted into young ones. In some of the more complex forms of Poly- gastrica the fissiparous mode of generation exhi- bits modifications which are extremely curious. In the beautiful Vorticella, whose bell-shaped bodies are supported on long and exquisitely irritable stems, the division commences at the large ciliated extremity of the animalcule, from which point it gradually extends in a longitudi- nal direction towards the insertion of the stem, dividing the body into two equal portions, one or both of which becoming speedily detached from the pedicle, might easily in this state be mistaken for creatures of a different genus, and have in fact been described as such by many authors. The new animalcule, when thus deprived of its pedicle, is seen to be fur- nished with cilia at the opposite extremity to that on which they were previously found, while from the other end, originally the mouth, a new foot-stalk becomes gradually developed, and the creature assumes the shape proper to its species. If one of the bells remain attached to the pedi- cle, it continues to perform the same movements as before the separation of the new animalcule ; but if both become detached, the foot-stalk perishes. In the strangely compound symmetrical bo- dies of Gonium a provision for separation appears to be made in the detached portions of which each perfect animal is apparently com- posed. The body of Gonium pectorale con- sists of sixteen minute transparent globes of unequal size, arranged in the same plane. This beautiful animalcule is propagated by a separation of its integrant spherules, the creature dividing into four portions precisely similar to each other, and composed individually of one of the central globules united to three of the smaller marginal ones ; and no sooner is the division accomplished than the component globes of each portion increasing in number, the new animalcules assume the dimensions and appearance of that of which they originally formed parts. In the Gonium pulvinatum the fissiparous mode of generation gives origin to a still more numerous progeny. The young animalcule is a minute, flat, diaphanous and quadrangular membrane, which swims through the fluid in which it is found by movements sufficiently in- dicative of its animal nature : as it enlarges, the surface is seen to become marked by two series of parallel lines which cross each other at right an- gles and divide the creature into smaller squares, which ultimately separate and become distinct representations of the original animalcule. Some of the Nematoid worms, as the Nais, are likewise said to propagate by spontaneous division. Gemmiparous generation. — This mode of re- production, like the fissiparous, is confined to the lowest tribes of animal existence, and the creatures which propagate in this manner are unprovided with any apparatus specially appro- priated to generation. The young appear as gemmae or buds, which at certain periods sprout from the homogeneous parenchyma which com- poses the body of the parent, and these buds gra- dually assuming the form of the original by a kind of vegetative growth, become in a short time capable of an independent existence. The gemmiparous type of the generative function is met with through a wider range of the animal kingdom than the last, existing under modified forms in many species of Polygastric Infusoria, and of Polyps, as well as in Sponges, the Cys- tiform Entozoa, and probably in some Acale- phae. It is in the Cystoid Entozoa that we find it in its simplest form. In the Cysticercus and like- wise in the Ccenurus, the transparent membra- nous bag of which the animal consists is filled with a glairy fluid, in which occasionally young hydatids are seen floating about. These young Cysticerci in the earliest period of their forma- tion are seen to pullulate from the parietes of the parent sac, and gradually enlarging they ultimately separate from their connexions, be- coming detached and perfect animals. Many of the Polygastrica are multiplied by a similar process, of which the Volvox globator may serve as an illustration. This beautiful ani- malcule is a minute diaphanous globe, which under the microscope is generally seen to con- tain a variable number of smaller globules, which are the young : these, when first discoverable, are .attached to the inner surface of the parent, but speedily detaching themselves they are 408 ORGANS OF GENERATION. found rolling loosely within the body of the larger animalcule, effecting their rotatory move- ments by the agency of cilia of extreme minute- ness, which under a good microscope are seen to cover their external surface. The contained globules having attained a sufficient maturity, the parent volvox bursts, and thus by its own destruction allows its progeny to escape from their imprisonment. The multiplication of these animalcules is effected with considerable rapidity, and it not unfrequently happens that even before the escape of the second generation the gem mules of a third may be observed within their bodies, which in like manner advancing through similar stages of development will ter- minate by their birth the existence of their parent.* It would appear from the observations of Professor Grant, that in the sponges, notwith- standing their different form, the process of re- production is entirely similar. In these curious animals the gemmules are developed in the substance of that living parenchyma which coats their porous skeletons, and when mature are expelled through the fcecal orifices to com- mence an independent existence. When sepa- rated from the parent sponge, these gemmules, like those of the volvox, are ciliated over a great portion of their surface, and being thus endowed with a power of locomotion, are enabled to swim to a considerable distance in search of a situation adapted to their future growth, until having at length selected a permanent support, they become attached, and developing within themselves the spicular or horny skeleton pecu- liar to their species, they gradually assume the porous texture and particular character of the sponge from which they were produced. But it is in the gelatinous Polypes that we meet with the most perfect forms of gemmi- ferous propagation : of this the Hydra viridis, orfresh-water polype, affordsan interesting illus- tration, and from the facility with which it may be procured and examined by glasses of very ordinary powers, it is well calculated to illus- trate the mode of generation which we are at present considering. The body of this simple polype is transparent, and under the microscope appears to be entirely made up of translucent granules, without any trace of internal appara- tus appropriated to reproduction. The gem- mules by which it is propagated sprout from some part of the surface, appearing first as mere gelatinous excrescences, but gradually enlarging they assume the form of their parent, acquiring similar filamentary tentacles and a gastric cavity of the same simple structure. As long as the junction between the polype and its off- spring continues, both seem to enjoy a commu- nity of being, the food caught by the original one being destined for the nourishment of both ; but at length, the newly-formed animal having at- tained a certain bulk, and become capable of employing its own tentacles for the prehension of food, detaches itself with an effort, and as- * [Some physiologists, however, refer the genera- tion of this creature to the fissiparous mode. See the succeeding article. — En.] sumes an independent existence. This mode of multiplication is exceedingly rapid, a few hours sufficing for the perfect developement of the young creature ; and not unfrequently even before its separation, another gemmule may be observed emerging from the newly-formed polype, soon to exhibit the same form and ex- ercise the same functions as the parent from which it sprouts. The propagation of some of the lithophytour polypes resembles that of the hydra, the young being produced from buds or gemmules, which sprout from the living investment of their cal- careous skeleton. Such are the Fungia, in which the young are at first pedunculated, and fixed to the laminae upon the upper surface of the mass from which they spring ; in this state they might readily be mistaken for solitary Caryophyllia, but in time they separate from the parent stock, and loosing the pedicle which originally supported them, they assume the form of their species. Oviferous generation. — In the third, and by far the most numerous division of the animal kingdom, the young are derived from ova or eggs, in which the germ of the future being is evolved, and from which the young animals escape in a more or less perfect state. It will be seen that the ovum which gives birth to all the higher animals differs essentially from the gemma furnished by the gemmiferous classes ; in the gemmiferous type the bud or offshoot of the parent appears by a kind of vegetative evolution to assume the proportions and functions of the original from which it sprang. The ovum we would define as a nidus, containing not only the germ of the future animal, but a sufficient quantity of nu- tritious matter, serving as a pabulum to the embryo during its earliest state of existence, and supplying the materials for its growth until sufficiently mature to derive them from other sources. We have already shewn that in the fissiparous and gemmiferous animals there is no necessity for any special generative appa- ratus, but in the oviferous classes we find, for the most part, a distinct system, more or less complicated in structure, in which the repro- ductive ova are developed and matured. It must be confessed, however, that in the present state of our knowledge upon this subject we are not prepared to state how far the existence of a generative system is exclusively confined to the ovigerous type. We are well aware that many authors describe generative canals to exist in several of the polypiferous tribes, although the reproductive germs produced from them resemble in their ciliated organs of pro- gression and mode of development the gem- mules of less elaborately organized polypes; yet, on the other hand, as we have abundant evidence to prove that such polypes as have the ovigerous canals most distinctly formed, as the Actinias for instance, produce their young per- fectly organized and evidently developed from true ova, we are content, in the present state of our knowledge upon this subject, to regard the presence of generative canals as co-existent with ovigerous generation, and shall leave ORGANS OF GENERATION. 409 future observations to determine more accu- rately the mode of reproduction in the corti- ciferous polypes, -which is a subject at present involved in much contradiction and obscurity. Taking this view of the subject, we find, upon cursorily glancing over the ovigerous classes of animals, that important modifications of structure in the generative system render further classification necessary. In the lower forms, ovigerous organs only have been dis- covered, in which the ova are secreted, and when matured, escape from the body, fit in every respect for the production of a new animal. In other instances, in addition to the apparatus immediately appropriated to the de- velopement of the ova, we find a superadded portion destined to furnish a secretion which is essential to their fertility, forming an apparatus of impregnation. Sometimes the impregnating organs are found in every individual, appended to the ovigerous parts, rendering each creature sufficient for the impregnation of its own ova : in other instances, although each animal pos- sesses both ovigerous and impregnating or- gans, the cooperation of two individuals or more is necessary to fertility ; and in other cases again, the apparatus which furnishes the ova, and that destined to the production of the im- pregnating fluid, are found in distinct indivi- duals, distinguished by the appellations of male and female : we shall accordingly di- vide all oviparous animals into the following groups : — 1. Such as are provided with ovigerous organs only. 2. Animals having, in addition to the ovige- rous apparatus, a glandular structure, the secretion of which is probably subservient to the fertility of the ova. 3. Ovigerous and impregnating organs, co- existent in each individual, but the cooperation of two or more needful for mutual impregna- tion. 4. The ovigerous and impregnating appa- ratus existing in distinct individuals. First Division. — Animals in which ovigerous organs only have been distinctly recognized. It would seem from the observations of Ehrenberg that some of the Polygastrica be- long to this division, although the exact nature of the generative system in such species remains still a matter of uncertainty. In the Kolpoda Cucullus the spawn consists of a loose mass of ova, connected by delicate filaments, from which the young are gradually evolved after their extrusion from the parent animalcule, and some of the parenchymatous Entozoa appear to be similarly circumstanced. In the Acalepha;, at least in such as have been most attentively examined, the generative system conforms to the type at present under consideration. From the researches of Gaede and Eysenhardt it appears that the ovaria are four in number, disposed in a cruciform manner upon the dorsal aspect of the body or that which is opposite to the mouth. These ovaria, which at certain seasons of the year are re- markably distended and often beautifully VOL. II. coloured, open into the interior of the stomach- The young Medusae are hatched in the ovaria, and afterwards escaping into the alimentary canals excavated in the substance of the body, acquire in that situation a very perfect state of development, and are ultimately excluded through the oral aperture, or in the llhizosto- matous species through the ramified canals of the pedicle. In the fleshy polypes (Actinia?) the ovigerous system consists of long, convoluted filiform tubes, contained between the stomach and the parietes of the body, and separated by partitions which divide that space into compartments. These tubes are attached by a delicate mesen- tery, and according to Spix open in an irregular manner into the digestive cavity, into which the ova escape. The period or mode in which the eggs are hatched is unknown, but that the young escape fully formed and in every point resembling their parent through the stomachal orifice is attested botli by Dicquemare and Blainville.* The different forms of Echinodermata pre- sent a similar simple arrangement of the gene- rative apparatus. In the Asteriadcs each ray is furnished with two clusters of short ovigerous tubes, which are closed at one extremity, but open at the other into a cavity common to each group. These organs open by a series of aper- tures placed around the circumference of the mouth at the base of each ray. In the spring these ovaria are distended with eggs of a reddish-brown colour, which are expelled in clusters and left upon the beach exposed to the influence of the sun, where they are ulti- mately hatched.f The radiated type of structure is likewise manifest in the disposition of the generative organs of the Ecbinida? : in these the ovaria are never single cr simply bilobed, but are at least four in number, or, as is generally the case, five. Each ovigerous organ consists of a simple dilated sacculus, which at certain seasons is distended with ova, and at such times in some species, as in the edible Echinus, the eggs are sought after as an article of food. The ovaria open externally by a corresponding number of simple apertures, which are placed around the anal orifice when it is central, but otherwise are considerably removed from this point. Nothing analogous to a male apparatus has been detected in the Echinida. The eggs are deposited in spring in the recesses of rocks or among the fucus which covers them ; and before they are hatched the young may be dis- covered in the interior partially covered with a calcareous shell, the rest of the integument still remaining membranous. * Spix and Delle Chiajc assert that there are other filiform tubes mixed up with the ovarian ducts, which they regard as the testes, but neither the observations of other authors nor our own exami- nations confirm this view of the subject. t Tischer and Spix describe a singular flexuous intestiniform organ which is found upon the dorsal aspect of the stomach as a male apparatus, and Blainville considers this part as in some degree connected with generation. 2 E 410 ORGANS OF GENERATION. The Holothuridse present in the elongated form of their bodies an evident approximation to the annulose type of structure, and a propor- tionate concentration of the generative system ; in these we find but one ovary floating loosely in the visceral cavity, and composed of numerous very long cceca, which terminate by a single orifice placed on the median line, near the oral extremity of the animal.* The eggs when dis- charged are connected into masses composed of long strings of ova, but the mode of their development is but little known. Although from the relations of the Mollus- cous division of the animal kingdom we might infer that a more elevated type of structure would characterize their organs of reproduction, the present state of our knowledge of the anatomy of these creatures compels us to arrange the lowest orders of that extensive class with those tribes which only possess an ovigerous system ; for although an androgynous confor- mation is presumed by many to exist in all Bivalves, the presence of any superadded im- pregnating portion has not yet been pointed out, and even the course of the ova in their passage from the ovarian cavity remains a mat- ter of speculation. In the Conchiferous order, from causes sufficiently obvious when we con- sider the peculiar structure of the animals which compose it, the full development of their numerous ova could not be accom- plished in the ovary itself, which occupies a large portion of the body, as any material in- crease of bulk produced from this cause would materially interfere with the closing of the shell ; at an early period, therefore, the ova are transferred from the nidus in which they were formed to the branchial fringes, between the lamina; of which they perfect their growth, and are fully exposed to the influence of the element around them. Oken traced a canal through which he supposed the ova to be con- veyed directly from the ovaria to the gills ;f but notwithstanding his observations Carus contends J that the eggs pass into the stomach through one of the openings hitherto considered as belonging exclusively to the biliary ducts, whence they are evacuated through the mouth and conveyed into the openings of the gills by the water which flows between the pallial laminae from before backwards, and ultimately escape by two canals which open below the anal tubes. In the Tunicata, and also in those forms of the Gasteropodous Mollusca which most nearly approximate the Conchifera in the details of their organization, the ovary is imbedded in the substance of the liver, and the ova are dis- * Here, also, Blainville conjectures that there is a supplementary impregnating portion, but it is evident that in a treatise like the present it would be worse than useless to recapitulate the surmises of authors upon subjects only capable of solution by positive demonstration, and we shall therefore endeavour rather to adhere strictly to the narration of what is clearly established by observa- tion, than to indicate what theory or analogy would lead us to suspect. t Goetting, gel. Anzeigeu, 1806. } Introduct. to Comp. Anat. charged through a simple duct, unprovided with any appendage which can be looked upon as a male apparatus. It is true, indeed, that in all these cases the walls of the oviduct may themselves furnish a fertilizing fluid, and by many physiologists they are supposed thus to supply the want of male parts ; such an hypo- thesis, however, is, to say the least of it, entirely gratuitous ; but as it is more our busi- ness to trace the development of organs than the modes in which their deficiency may be supplied, we are content to leave the question without further discussion in this place. Second Division. — Animals provided with ovigerous organs combined with an addi- tional secreting structure, probably sub- servient to the fertilization of the ova. In this type of the generative system it must be obvious that the function attributed to the superadded portion is by no means indubitably substantiated, the opinions of physiologists relating to its office being rather based upon analogical reasoning than supported by direct evidence ; and, in fact, some authors deny entirely that a necessity for the impregnation of the ova is more evident in this division than in the last. Nevertheless, although it is im- possible distinctly to prove the identity in function between the appended portion and the testis of higher forms of organization, the evidence afforded from the position which it invariably occupies, and from the considera- tion of the parts connected with generation in dioecious animals to which we are insensibly conducted by this species of Hermaphrodism, is sufficiently cogent to warrant our application of the term ovarium to the nidus wherein the ova are produced, and to justify us in designa- ting the accessory organ as a testis or apparatus for impregnation. The Tsenioid Sterelmintha furnish us with one of the simplest examples of this arrange- ment of the generative organs. In the long and tape-like bodies of these Entozoa each segment, with the exception of the smaller ones near the head, possesses distinct ovigerous and impregnating structures. The female part of the apparatus occupies the centre of the joint, and consists of lateral tubes ramifying from a centra! canal, which at times may be seen to be full of minute granular ova. From these ovigerous canals a duct issues, which commu- nicates with the lateral pore and receives before its termination two delicate tubes, recognizable under the microscope as dark lines imbedded in the pulpy segment, and which may be pre- sumed to furnish an impregnating secretion. In the Rotifera, or wheel-animalcules, the female apparatus consists of two long and comparatively wide sacculi, in which the ova are developed ; these open at the anal orifice, and receive near this point two narrow cceca, which, as in the last case, may secrete a fer- tilizing fluid, serving to impregnate the eggs prior to their expulsion. The ova of these minute creatures, before the escape of the young, are exceedingly beautiful subjects for the microscope, the wheels of the embryo ORGANS OF GENERATION. 411 being easily distinguished in rapid action through the pellucid coverings of the egg. In the Cirrhopoda we have most probably an example of this mode of generation, pre- suming, that is, that the opinions of Cuvier upon this subject are correct. These opinions, it is true, have been disputed by various authorities, as will be evident on reference to the article Cirrhopoda ; but their correct- ness has been so fully supported by the dissections of John Hunter, recently given to the world,* that it seems best at least to pause before repudiating the conclusions to which these great anatomists, unacquainted with the labours of each other, were indivi- dually conducted. In the Cirripeds the ovaria are two in number, placed on each side of the stomach ; the two oviducts which proceed from these unite to form a single elongated tube, the parietes of which are thick and apparently glandular. It is evident that in this case the walls of the common canal, or ovipo- sitor as it is usually termed, may serve to secrete a seminal fluid, impregnating the eggs at the period of their extrusion ; and such, in the opinion of the authors above mentioned, is a part of its office. Third Division. — Ovigerous and impreg- nating organs co-existent, but the co- operation of two individuals necessary tor mutual impregnation. This arrangement of the generative system occurs in some of the Parenchymatous Entozoa, in the Annelida, and also in the Pteropod and some Gasteropod Mollusca. Some of the Entozoa, as Fasciola and Planaria, furnish the simplest examples of this hermaphrodite condition. In these creatures the male organs consist of spermatic coeca, communicating with a minute extensible penis, which is placed behind the oral sucker. Near the penis a small orifice is seen, leading to the ovigerous canals, which have no communication with the impregnating apparatus ; and the copula- tion of two individuals is thus indispensable to a reciprocal fertilization of the ova. Those of the Annelida in which the gene- rative system is best understood are androgy- nous, and mutually impregnate each other, although it is probable that in the tubicolous genera, which are immoveably fixed to the same spot, and almost deprived of locomotion, each individual may in itself be sufficient for reproduction. In the Abranchiate and Dorsibranchiate Annelida the male apparatus is composed of several pairs of secreting bodies, arranged on each side of the mesial plane, those of the same side communicating with each other by a common vas deferens. In the Leech the vasa deferentia, which convey the secretion of the numerous testicular masses, terminate in a long protractile tubular penis, and at a short distance behind this the opening which leads * Catalogue of the Physiological Series of Com- parative Anatomy contained in the Hunterian Collection, vol. i. to the female parts may be discovered. These latter consist of a simple uterine sacculus, or receptacle for the ova, to which two minute ovaries are appended. The congress of two individuals is effected by the reciprocal in- troduction of the organs of intromission into the vulva;. In the Earthworm and Nais the intromittent apparatus is deficient, so that some authors have even doubted that the process of copulation, which is undeniably essential to fecundity, does more than stimulate each individual to self-impregnation. In the Earth-worm, as well as in Arenicola and Aphrodita, the ova, after escaping from the ovaria, are retained in the cellular meshes which surround the alimentary canal, in which they are not unfrequently hatched, the young being most probably expelled through a tubular aperture at the posterior extremity of the body. As regards the generative system, the Pte- ropod Mollusca approximate the more complex type seen in the Gasteropoda. In Clio borealis, the ovary, which is partially enveloped by the liver, gives off a slender duct, which, after a short course, plunges into a glandular tube ; this, becoming gradually narrower, terminates in a round sac placed on the left side of the head, where it opens externally : near this point is the penis, or organ of intromission, communicating with a small sacculus, by which the male secretion is probably furnished. Fig. 200. Testis of Helix. The most complicated forms of this species of hermaphrodism are met with in the Gas- teropod division of Mollusca, existing through- out the Nudibranchiate, Tectibianchiate, In- ferobranchiate, and Ilcteropod orders, as well as in those pulmonary genera which are un- provided with a calcareous operculum. In all these cases the testis is single and divided into lobuli, connected together by the divisions of the vas deferens so as to exhibit a racemose arrangement, and each lobule, on minute in- spection, is found to consist of little peduncu- lated vesicles (jig. 200). A slender vas defe- rens conducts the secretion of this testicle to the base of an intromittent organ of a most sin- gular description ; this is a muscular tube of great length, which, when not in use, is in- verted and concealed within the body, but ca- pable of protrusion at the will of the animal. The female portion of this system is composed of one ovary, provided with an ample and tortuous oviduct, which serves, indeed, as a kind of uterus or egg receptacle, wherein the 2 e 2 412 ORGANS OF GENERATION. ova are retained until ripe for extrusion. Near the termination of this oviduct are placed several additional appendages, some of which are apparently destined to furnish an invest- ment for the ova, whilst one, which is con- stantly present, is probably a reservoir for the seminal fluid required to fertilize the eegs as they are expelled. (See Gasteropoda.)" The external parts are so disposed that during the copulation of two individuals the male organ of each is introduced into the orifice leading to the female apparatus of the other, both thus impregnating and being im- pregnated at the same time. In Lymnai/s stagnalis we have a curious exception to this mode of copulation, for in this animal the sexual organs are so placed that mutual impregnation is impossible, and accordingly fecundation is accomplished by a combination of individuals, each of which performs the office of a male to another, while to a third it acts the part of a female, and long strings of them are often seen thus united. Fourth Division. — Sexes distinct, that is, the ovigerous and impregnating organs placed in separate individuals. This type of the reproductive apparatus extends through a wide range of animals, and is found in a great number of classes utterly dissimilar in outward form and internal struc- ture ; so that, in order to give a connected view of the comparative organization of the parts of generation, we shall be unavoidably com- pelled to group together animals widely sepa- rated by the laws of zoological arrangement. Feeling, however, that by so doing we shall lay before our readers a much more easily intelligible comparison of the organs belonging to our subject, we shall not scruple to bring together, in one view, analogous forms of the generative apparatus, in whatever classes they may be found. Animals in which the sexes are distinct may be divided into three classes ; the first including such as are oviparous, the second embracing the ovo-viviparous orders, while the third will comprehend the strictly viviparous animals. It will be seen that the terms here employed have been used from time immemorial, but nevertheless in a widely different sense to that in which the present state of our knowledge sanctions their application. To us it appears that we ought to regard all creatures as ovipa- rous whose offspring, at the period of their escape from the ovum, are sufficiently mature to admit of their independent existence. In the ovo-viviparous division, on the contrary, the ova are hatched and the embryo expelled at an early period of its formation ; the embryo is thus born in an extremely imperfect state, the materials for its future developement being supplied by the mammary secretion of the parent ; such is the case with all the marsupial orders. In the vivipara the earliest stages of growth are precisely similar to those which mark the progress of evolution in the ovi- parous type, and the provisions made for the nourishment of the rudimentary being in every respect analogous ; the great distinction consists in the subsequent maturation of the embryo within a uterine cavity, and the forma- tion of a placenta, which characterizes the highest form of mammiferous animals. The oviparous classes, which form by far the most numerous division, produce their young from ova, in which the germs of the future beings are developed for the most part subsequent to the expulsion of the egg from the body of the parent. In this case the ovum necessarily contains a sufficient store of nourishment for the support of the embryo during the whole period of foetal life, at the termination of which it is produced in a suffi- ciently advanced stage of its growth to render it capable of independent existence. It will readily be perceived that under this division we include many animals which, according to the old meaning of the terms, were looked upon as ovo-viviparous or viviparous in their mode of reproduction ; a distinction which, as the words have been hitherto applied, appears to the writer by no means sufficiently grounded upon physiological views to admit of its conti- nuance. It is certainly very true that some ani- mals included in this division are found to pro- duce their young in a living state ; but the mere hatching of the egg within the oviductus of the mother, instead of subsequent to its ex- pulsion, is not a circumstance of sufficient importance to be regarded as constituting another type of the generative process, more especially as such an occurrence is entirely fortuitous, observation having proved that the same animal at one time produces its young alive and at another in the egg state, in obedience to circumstances connected with food, tem- perature, or confinement. With this extension of the term, oviparous animals in which the sexes are distinct will be found in many classes belonging to the diploneurose, cyclogangliate, and vertebrate divisions of the animal kingdom, combined with modifications in the structure and arrangement of the generative apparatus, which it will be our business to trace. The earliest appearance of this type is found in the cavitary Entozoa (Coelelmintha), and the sexual organs, both in the male and female of these creatures, may be regarded as ex- hibiting the greatest possible simplicity of structure, consisting merely of secreting tubes, which in one sex produce the seminal fluid, in the other develope the ova. The seminal organ, or testis of the male, is generally a single tube of extreme length and tenuity, winding in large folds around the alimentary canal, and occupying a large portion of the abdominal cavity ; when unravelled, its length is found to be many times that of the animal ; at one extremity it dwindles down to a filament of the utmost tenuity, which floats loosely in the juices of the body, whilst at the op- posite end it terminates in a prolonged tubular penis, or organ of intromission, placed near the anal orifice. In the females of some species, as in Ascaris, the ovigerous system is composed of two tubes, each exceeding in length and tortuosity the seminal vessel of the ORGANS OF GENERATION. 413 male, and measuring in some cases upwards of six feet. These tubes, after becoming con- siderably increased in size so as to form a kind of receptacle for the ova which they generate, unite prior to their termination in the vulva, the aperture of which is found upon the ventral surface of the body at about one third of its length from the anterior extremity. In Strongylus the ovarian tube is single, and its orifice nearer to the mouth. In many species, as Filaria, the young are produced alive, the ova being hatched in the oviduct, a sufficient proof of internal impregnation having been accomplished. The Myriapoda, in every part of their struc- ture, form the transition from the Annelida to the articulated classes properly so called. They are divided by entomologists into two classes, the lulida or Chilognatha, and the Scolopen- dridte or Chilopoda, a division strictly in con- formity with their internal structure; the former in fact represent the Annelida; like the Abran- chiate division of that class, they breathe by air-sacs, communicating with spiracles seen upon the exterior of their bodies. The Scolo- pendra, on the contrary, respire by tracheae, which permeate their viscera, as in the insect classes. In the generative system of these creatures a similar relationship is evident. In lulus, the generative system occupies the ante- rior segments of the body, the sexual apertures being found upon the rings near the cephalic extremity, whilst in Scolopendra they are placed, as in insects, near the anal orifice. As regards the internal sexual organs of lulus, but little is known conclusively, and our own researches upon this point have not been sufficiently satis- factory to enable us to speak positively con- cerning them, although the result leads us to suspect that in these creatures not only are the sexual parts analogous to those of the Anne- lida, but that, as in many of that class, the ova are retained in cellular interstices surrounding the intestinal canal for some time prior to their expulsion. In the Scolopendra the generative organs are more easily distinguishable, and much resem- ble those of insects ; they are, however, exceed- ingly curious. In Jig. 201 we have represented the male apparatus of the Scolopendra mnrsi- tans. The testes (a, a, a) are seven in number, and closely packed in parallel lines; each testis is composed of two parts, precisely similar to each other, which are seen separate at b ; from each extremity of the fusiform testis arises a narrow duct, so that there are fourteen pairs of ducts arising from the fourteen secreting organs. Each of the testicular bodies is hollow inter- nally. The ducts ultimately end in a common tube (c), which soon becomes enlarged and tortuous, terminating by a simple aperture near the anus. Just prior to its termination, the en- larged canal receives five accessory glands, four of which (d, d, d, d) are intimately united, until unravelled, as seen in the figure, while the fifth (e) is a simple ccecum of considerable length. The ovarian system of the female Scolopen- dra is a single tube, apparently without secon- dary ramifications. Fig. 201. Male generative organs of the Scolopendra morsitam. Insects. — In the numerous and diversified tribes of the insect world a great uniformity is observable in the general arrangement of the generative apparatus. The sexes are invariably separate, but while the internal organs are con- stantly double and symmetrically disposed on both sides of the mesial plane, the external parts which are subservient to copulation are removed to the posterior extremity of the body, and are single. Throughout the whole class the sexual system only arrives at that state of perfection which is compatible with reproduc- tion in the perfect or imago state of the animal, although it may be detected in a rudimentary form even in the larva, being gradually more and more perfected during the developement of the pupa. The business of procreation in insects thus exclusively belonging to the per- fectly formed creature, is accomplished only at the termination of their existence, and the whole tribe is remarkable from this circumstance. The internal generative organs in male in- sects are described as consisting of three por- tions, the testes with their vasa deferentia, the vesicular seminales, and the canalis excretorius. The testes, or, in other words, those portions of the apparatus which are supposed to furnish the essential part of the fecundating- fluid, like the rest of the glandular system, consist of cceca or utricles floating loosely in the abdominal 414 ORGANS OF GENERATION. cavity, immersed in the juices of the body, from which they derive their secretion. Never- theless, although essentially constructed upon similar principles, the testicular cceca present a singular diversity of form in different genera, and some of the modifications are sufficiently curious, although in the present state of our knowledge it would be hopeless to attempt to explain the reason of their existence. Midler, from a comparison of the researches of various authors upon this subject, has given the follow- ing summary of the principal forms of the sperm-secreting organs, and although the cata- logue of varieties might doubtless be considera- bly extended, those given will abundantly an- swer our present purpose. Beginning from the tubular vessel, which is the simplest form of the testis, he traces it through the various com- plications here enumerated. 1. Simple tubes not branched, but more or less convoluted and closed at one extre- mity. 2. Spiral tubes similarly closed, as in Spho- drus t err kola. 3. Spiral tubes rolled up into little balls, as in Carabus auratus, Aptiuus displosor, Dytiscus, &c. 4. Simple tubes irregularly branched, each branch vesicular near its extremity, as in Prionus coriarius. 5. Simple tubes, divided in a verticillate manner, each division being terminated by a capsule ; Scurabteus nasicornis, (Swammerdam.) 6. Simple tubes, divided as the last, but each division ending in a vesicle, as in Trie hius fuse iatus. 7. Simple tubes ending in stellated capsules, the apices of which are produced into slender tubes ; ISepa cinerea, (Swam- merdam.) 8. Simple tubes giving off a series of canals, each of which is terminated by a disc- shaped capsule ; Cetonia aurata. 9. Simple tubes, ending in flower-shaped capsules, i. e. each capsule consisting of a central vesicle, with other smaller ones placed around it, as in Asida gigas, CEdemera adcarutu, Diaperis violacea, Tenebrio obscurus, (Edemera carulea, &c. 10. Simple tubes, each terminated by a trans- verse capsule, resembling the anther of a flower, as in Apis, Bombyx, Scaris, Calvinia, &c. 11. Simple tubes, dividing into minute radia- ting utricles ; Bostrichus capucinus. 12. Simple tubes, each terminated by a cap- sule, which is covered externally with innumerable little vesicles or utricles, as in Musca asilus, Eiater murinus, Blaps gigas, Telephones J'uscus. 13. Simple tubes, ending in an elongated sac- culus,to the sides of which are appended small vesicles arranged in longitudinal rows, as in Semblis bicauduta. 14. Simple tubes terminating in verticillate utricles, as in Clerus alveolarius. 15. Simple tubes, from which arise utricles Fig. 202. arranged like the teeth of a comb, as in Hydrophilus piceus. 16. Simple tubes, terminated by a simple sac- culus ; Gyrinus nutator. 17. Simple tubes, terminated by a bunch of vesicles. 18. Simple tubes, dividing into minute canals, forming a kind of cauda equina ; Tri- chodes apiarius. 19. Branched tubes, each branch being termi- nated by . a vesicle, as in Stuphilinus maxitloHM. ( Fig. 202.) 20. Tubes very much branched, some of the ramusculi ending in bunches of leaf- like utricles, others dilating into pe- dunculated vesicles ; Sylpha obscura. ( fig. 203.) 21. Simple loculated utricles, as in Ephe- mera. It is manifest from this sur- vey that, although the secern- ing organs differ so much in form, the canals composing them invariably terminate in blind extremities ; nor is it less obvious that the nature of the testis does not depend upon any peculiar arrange- ment of the seminal tubes, but upon the increase of surface obtained by the various ar- rangement of the vessels. Se- cretion, therefore, here, as in every other case, is effected by the internal surface of tubes, utricles, sacculi, &c. the same end being accomplished in some cases by means of very long simple canals, which in others is effected by smaller Testicle of Staphy- branches, tubes, or agglome- linus muxillosus. rated vesicles. Fig. 203. V Testicle of Silpha obscura. Appended to the excretory ducts of the testi- cular organs, near their termination, is found a group of caecal tubes, evidently destined to provide an accessory secretion; these have been named from analogy vesicula seminules. They ORGANS OF GENERATION. 415 vary much in their form, being sometimes elon- gated, tortuous, convoluted, or ventricose, or at others short and straight. The seminal vesicles are generally two in number, even in those Lepi- doptera in which the testis is single. In some insects, as Tenebrio molitor and Hydrophilus piceus, there are four; in others, as Dytiscus marginalis, six ; and in Locusta and Blatta, they are very numerous. In some insects these tubes are found to be of surprising length ; thus in Oryctes nasicornis they are twenty times as long as the body, and in Cetonia aurata even sixty times the length of the animal. The vasa deferentia and vesiculse seminales ulti- mately terminate in one common tube, the ca- nalis excretorius, which communicates with the root of the penis; this canal is composed of muscular walls largely supplied with tracheal vessels, serving as a receptacle for the genital secretions, and no doubt is the agent by which, during coition, their expulsion is effected. The penis of insects is a hollow tube, capable of being protruded from the anal extremity of the body : its texture is generally membranous, but sometimes horny, and its shape exhibits considerable variety ; it is usually cylindrical or nearly so, becoming more slender towards its termination. In Cliermis pyrus, however, the end is enlarged ; in the common wasp it is spoon-shaped; in Cruhro bilobed, and in some Vespa curved and bifid at its extremity. In Musca vivipura its apex is covered with spines ; in Tyrop/iaga putris and some other Muscidaa it is spiral. The penis of Coleoptera is furnished with a bivalve sheath, destined to open the vulva of the female prior to its inser- tion. In some Diptera (Muscidae) a remark- able inversion of the usual arrangement of the organs of copulation is observable ; in these the females are provided with a retractile penis, whilst in the males the generative apparatus terminates by a simple aperture. During coi- tion in this case, it is the penis of the female which is introduced into the genital opening of the male, and thus becomes the recipient of the fecundating fluid. The Dragon-flies (Libel- lula) are remarkable from the position which the male organ is found to occupy, being placed under the anterior part of the elongated abdo- men, but in the female the sexual aperture occupies the usual situation near the anus. This arrangement accounts for the singular position which these insects assume during copulation. In addition to the organs above enumerated as composing the male system in insects, we may notice appendages which are found in some tribes which materially assist in effecting the intercourse of the sexes : these are named prekensores, and serve to seize and secure the female during coitus. These holders assume a great variety of shapes, and likewise are diffe- rently disposed according to circumstances. They generally surround the aperture through which the penis is extruded, but in Libellula the mode in which the sexes embrace each other renders additional security indispensable; in this tribe, therefore, besides the anal preken- sores, an additional pair of forceps is placed under the second abdominal segment. The prehensores are generally two in number; but in many Lepidoptera, Conopis and Libellula, three are placed around the anus. In Culex there are two pairs. In Locusta morbillostz there are five, and in Formica six holders. In some tribes, as Megachilis, Agrionidas, and Locusta, they are retracted within the abdomen when not employed. In insects the ovigerous or female generative apparatus consists likewise essentially of tubes or cceca, the arrangement of which is tolerably uniform. They may be divided into the ovaria, the oviducts, the spermotheca, or receptacle for the seminal fluid of the male, the accessory glands, and the ovipositor, which latter is, in many insects, an instrument adapted to intro- duce the eggs at the period of their extrusion into situations suited to their developement. The ovaria are double throughout the whole class, each being composed of a variable num- ber of membranous tubes arising from the oviduct. Rifferschweils considers the ovaries to be formed upon two primary types, being either flagelliform, that is, composed of conical tubes of equal length, which are inserted at the same place at the extremity of the oviduct, as in the Lepidoptera, the Bee, &c. ; or racemose, consisting of short conical tubes, so proceeding from the primary branches as to render the ovary racemose or pinnated, such as they are in many Neuroptera, Coleoptera, and Diptera. The number of tubes composing each ovary varies in different genera and species ; some- times there are but two, at others four, five, six, eight, or twelve, and in the more prolific insects this number is much increased; thus, in Acrida viridisvima there are thirty, and in the hive-bee not fewer than a hundred and fifty cceca in each ovarian packet. The number of eggs will of course depend upon the number and divisions of these ovarian tubes, and thus while some insects only lay two, four, or six eggs, others will produce sixty or seventy, and some gregarious insects a much greater num- ber : thus the hive-bee will probably give birth to many thousand young, and in the Termite ant (Hermes bellicosus) the fecundity of the female is absolutely incalculable. This extra- ordinary fertility renders indispensable certain restrictions which we find imposed upon this numerous class, tending materially to limit their excessive multiplication. Thus, through- out the whole race one generation only is pro- duced from the same insect, the business of reproduction being usually the termination of its existence ; and in the most prolific tribes, namely, those which live in society, as the Bee and the Termite, one female only in each com- munity is found to be fertile, the sexual organs of all the rest remaining in a rudimentary or undeveloped state, although capable of de- velopement, should the destruction of the queen render such a provision for the preserva- tion of the race indispensably necessary. (See Inseota.) The oviductus or excretory canal common to the ovarian tubes of the corresponding side of the body, sometimes opens into the cloaca, 416 ORGANS OF GENERATION. the eggs escaping by the anal passage; but in other cases, having joined that of the opposite side, it terminates externally by a distinct aperture ; near its extremity, however, it re- ceives the auxiliary tubes or ccoca, namely, the spermotlieca and the accessory glands. The spei motheca is a membranous saecu- lus of varying size and shape, regarded by Herold and Malpighi as a receptacle in which the seminal fluid of the male is de- posited and retained, — an opinion which has been sanctioned by subsequent anatomists ; it is found only in such insects as deposit their eggs in slow succession, and is presumed to be a provision for the gradual fertilization of the ova during their transit through the ovi- duct. It is only upon this supposition that it is possible to account for the impregnation of some insects which are employed for a long period in the business of oviposition, as is the case, for instance, with the hive-bee, in which a single coitus fertilizes all the eggs that are laid for a space of two years, amounting some- times to twenty or thirty thousand in number; and yet, in this case, it is difficult to conceive how so small a reservoir, scarcely larger in- deed than the head of a pin, can retain a sufficiency of this fluid for such a purpose, a difficulty which is scarcely lessened by admit- ting the hypothesis of Dr. Iiaighton, who refers the act of impregnation rather to some pene- trating effluvium or uuru sem'maiis, which the seminal liquor may emit during a long period, than to actual contact between the semen and the ova. The auxiliary glands (glandule succenlu- riata ), which are appended to the oviduct of insects, perform an office which is by no means satisfactorily determined; the most usual sup- position is that they furnish some secretion connected with the investment of the ova, either for the completion of the shell, or, as is more probably the case, for the purpose of uniting them together by a tenacious mucus into the long strings or masses in which they are not unfrequently extruded. The structure of these secerning caeca differs in different insects, but will be found to conform in most cases to one or other of the following types: — ■ 1. Most frequently they are merely elon- gated tubes closed at one extremity while the other opens into the oviduct. 2. In some cases the primary ccaca give off secondary branches. 3. In others, as in Hippobosca, they are ramified tubes terminated by blind canals. 4. In Etater Murium they present a very remarkable structure, being composed of a number of triangular capsules united by canals arising from each angle until the terminal vessels are reduced to simple cosca. The ovipositor is the last part of the female generative apparatus of insects which we have to notice. This singular appendage to the oviduct presents many varieties in its structure, being adapted to the introduction of the ova into certain localities either fitted for their matu- ration, or, as is more frequently the case, suited to the necessities of the larva after its escape from the egg ; but a detailed account of the forms which this organ assumes in dif- ferent tribes would necessarily be incompatible with the limits of this article, and the reader is therefore referred for further information to the article Insecta. Some insects are ovo-viviparous in a mo- dified sense, and their offspring are produced in the larva or even in the pupa state, the eggs being hatched in the body of the parent, and the young matured to a certain extent before they are expelled. In such cases the oviducts unite to form a capacious matrix, in which at certain seasons the larvaa are contained either agglomerated in masses, or arranged parallel with each other in flat bands. In this state each larva is invested in a delicate membra- nous bag. It is remarkable that all these larvee are carnivorous, their office being to remove putrifying flesh ; hence the necessity of their being produced in such a state as immediately to commence the woik to which they are des- tined. Some Aphides, or plant-lice, are ovo-vivi- parous in the early part of the year, but ovi- parous as winter approaches, — a provision evi- dently intended to secure the preservation of the embryo during the inclement season, the eggs remaining unhatched until the return of spring. The Aphides likewise in their mode of gene- ration furnish the physiologist with one of the most extraordinary anomalies met with in the animal kingdom. From an accurate series of observations, first instituted by Bonnet, and subsequently confirmed by the indefatigable Lyonnet, it is now received as an established fact that the females of these insects have the faculty of giving birth to young ones without having had any intercourse with the other sex. From the experiments of these naturalists it appears to have been incontestably proved that if a female Aphis at the moment of its birth be rigorously kept from communication with others of its species, it will, if supplied with proper food, give birth to a brood of young ones, and not only so, but if one of the off- spring so produced be similarly treated, it like- wise will prove fruitful, and so on to the fifth generation, according to Bonnet, or even still further, as Lyonnet afterwards ascertained. Bonnet supposed, in explanation of this cir- cumstance, that the Aphides are truly andro- gynous, each being possessed both of ovige- rous and impregnating organs ; yet this sup- position is incompatible with the fact, that the male insect is almost as common as the female, and that the sexes copulate in the usual manner during the termination of the summer season. The only solution of this phenomenon appears to be that one intercourse with the male suf- fices for the impregnation of all the females which in one season spring from the same union. But the Aphides are not the only ex- amples of this curious fact, as some of the Branchiopod Crustaceans, as Daphnia pennuta, Mull. ( Monoculus pulex, L.) are equally ca- pable of producing fertile females through several successive generations ; nevertheless ORGANS OF GENERATION. 417 both Bonnet and Jurine observed that the fe- male Aphides and Branchiopods that were fertile without the usual intercourse of the sexes were less fruitful than their mother, and those of the last generation less so than the first. Arachnida. — In the Arachnida the gene- rative system, both in the male and female, is even more simple than that of insects. The testes of the male are two in number, each being an elongated membranous bag, closed at one extremity, whilst the opposite is conti- nuous with a slender and tortuous vas deferens, the terminations of which are indicated ex- ternally by two very small orifices distinguish- able on the under surface of the abdomen near its junction with the thorax. The apertures through which the seminal fluid is discharged are totally unprovided with any apparatus of intromission or excitement; in lieu of which many genera are provided with a singular sub- stitute, or at least with an organ supposed by some authors to be an exciting organ. This is found at the extremity of the maxillary palpus, but for a detailed account of its structure and presumed functions the reader is referred to the article Arachnida. The female organs of the Araneidae are equally devoid of complication. The ovaries are simple membranous bags, which occupy when distended a considerable portion of the abdomen, and are found to contain ova ag- gregated together in considerable numbers. From each of these ovigerous sacs a short canal leads to an aperture situated near the base of the abdomen, through which, when mature, the ova are discharged. The most re- markable circumstance observable in this form of the generative system is the complete sepa- ration which exists between the sexual organs of the two sides of the body, which, both in the male and female, not only do not com- municate internally, but open upon the exterior by distinct apertures ; the insulation is, in fact, so perfect that in some cases the eggs gene- rated in the two ovaria are laid at distinct and distant periods. According; to Audebert some spiders are rendered fertile for several years by one intercourse with the male. In the Scorpions the male generative ap- paratus consists of a testis composed of nu- merous tubes united together, so as to form a series of loops, the secretion of which is dis- charged externally by a double penis resembling that of some reptiles, which is protruded through a valvular aperture seen upon the ventral surface of the thorax. The female organs of the Scorpion, like those of the male, are composed of loops of tubes, uniting together at different points, and when distended with ova resembling a neck- lace of beads : they open by two canals, (vol. i. fig. 84, c, p. 205), at the same point which the sexual aperture of the male has been seen to oc- cupy, each having a small caecum or succentu- riate gland appended near its termination. The eggs of Scorpions are hatched in the oviducts, and the progress of the develop>ement of the embryo maybe easily distinguished through the transparent coats of the ovum, resembling most accurately that observed by Herold in the evo- lution of the young spiders, figures of which are given elsewhere.* Crustacea. — As in the Arachnida, the gene- rative system of Crustaceans is for the most part double, the parts belonging to the two sides of the body being generally completely distinct from each other, not only internally but at their termination. In the higher orders the testes of the male and the ovaries of the other sex are found to be situated in the dorsal region of the thorax ; in both cases these organs appear at first sight to be of a dense glandular structure, but, on examination, are found to be essentially composed of tubular convolutions. In both the male and the fe- male, the excretory canals are simple tubes, which, after some convolutions, terminate in the male by prominent apertures, found upon the eoxal portion of the fifth or posterior pair of true legs, and in the female by similar open- ings at the base of the third pair. As in Insects, the female organs have in many genera a sacculated appendage, or copu- latory pouch as it is termed, which is, in fact, analogous in function to the spermotheca of insects, serving as a reservoir in which the male semen is detained for the purpose of im- pregnating the eggs as they successively escape from the body. After their exclusion from the oviduct the eggs of Crustaceans are generally carried about by the female. In the Decapoda they are appended by a glutinous material to the false feet situated under the tail. In the Isopoda and others they are retained in recep- tacles formed by scales placed under the ab- domen, whilst in the Entomostracous forms, as well as in many Epizoa approximating the Crustacea in structure, a remarkable provision is made for perfecting the eggs external to the bodies of these minute creatures, the females being provided with one or two membranous sacs appended to the posterior part of the abdomen, into which the oviducts open, and in which the ova are retained until they arrive at maturity. Mollusca. — Several of the more perfectly organised Mollusca come likewise under this division of our subject. Such are the Pectini- branchiate Gasteropoda, in which the structure of the generative apparatus is sufficiently sim- ple. In the male a large testis, composed of racemose follicles, shares with the liver the convolutions of the shell : from this the seminal secretion passes by a long and tortuous vas deferens to the extremity of the penis, which is in these creatures an extensile and very muscular organ, situated on the right side of the neck, and not unfrequently of enormous size when compared with the bulk of the animal. The ovarium in the female Pectinibranchiate Gasteropods corresponds in position with the male testis ; the oviduct arising from it is capacious, glandular, and convoluted, serving in some genera, as in Turbo, as a receptacle * Vide Article ARACHNIDA. 418 ORGANS OF GENERATION. in which the eggs are frequently hatched. Near its termination the oviduct communicates with a glandular apparatus supposed to furnish the viscid envelope by means of which the eggs are generally agglutinated together. In the Cephalopoda likewise, as in the Mol- lusca generally, the generative system is single. In this class the testis is an azygos viscus, composed of elongated branched cceca, in- closed in a membranous capsule, into which apparently the seminal fluid escapes. The vas deferens is narrow, and convoluted at first, but afterwards it enlarges and becomes mus- cular in its structure, serving doubtless as an instrument for the expulsion of the semen. This seminal canal receives the duct of a large glandular mass, and dilating into a pouch, ultimately terminates at the root of a rudi- mentary penis, apparently adapted to intro- mission, although it has not yet been ascer- tained whether actual copulation takes place, or whether the ova are fecundated after their extrusion, as is the case with fishes. In the female Cephalopoda the ovarium, like the testis of the male, is azygos, and placed in the same situation. Its structure is remark- able, being a strong capsule, to the interior of which adheres a. cluster of vesicular bodies denominated ovisacs, from which, at certain seasons, the ova escape. From the ovarian capsule arises the oviduct; this is in some instances a single tube, but in others divides into two canals; in either case, before its ter- mination behind the base of the syphon, it passes through a thick laminated glandular structure, which secretes the dense coriaceous investment enclosing the ova, and the material which unites them into the racemose clusters in which they are usually found. Verlebrata Ovipara. — In the vertebrate divi- sion of the animal kingdom the generative system presents great varieties, although from the lower to the higher orders we may distinctly trace a series of gradations which, in a physio- logical point of view, are of the highest interest. In Fishes the ovaria are formed upon two distinct types. In the osseous fishes they are for the most part two large membranous sacs, which, when distended, occupy a considerable share of the abdominal cavity; these open by a short canal in the vicinity of the anus. In these capacious sacs the ova are developed : they are found united, together by a delicate membrane, and attached in numerous festoons to the walls of the ovary until sufficiently mature for expul- sion, when, breaking loose from their con- nexions, they escape into the ovarian cavity and are discharged through its excretory duct. In this case the Fallopian tubes found in other vertebrata do not exist, the oviduct being pro- longed from the ovary itself in the same manner as the duct of a secreting gland, and the whole apparatus, in fact, strongly resembles what we have found in the Conchifera and other Mol- lusks, the great distinction consisting in the necessity which here exists for the impregnation of the ova by the agency of the male. The fecundation of the eggs is effected externally, after their expulsion, and, in fact, it is the spawn rather than the female, which forms the object of the pursuit of the male, as in most instances both sexes appear as careless con- cerning each other as they are of the off- spring which they produce. The ova, which are incalculably numerous, are deposited in shallow water, where they may receive the influence of the solar beams, and in this situa- tion are eagerly sought after by the males destined to make them fertile; these, urged apparently by the necessity of ridding them- selves of an inconvenient load, discharge the secretion of their voluminous testes into the water, which, becoming diffused in the vicinity of the ova, is sufficient for their impregnation. In the males of this class of fishes the testes are of enormous size, equalling in bulk the ovaria of the other sex, and occupying a corres- ponding situation in the abdomen. Each testis is made up of a congeries of seminal canals, which, when inflated through the excretory duct, distend the whole organ. The seminal tubes are in most instances arranged parallel to each other, and are closed at one extremity while the other terminates in the common canal or vas deferens, which in every respect resem- bles the oviduct of the female. This is the most usual structure of the male apparatus of fishes, but in some, as in the Shad ( C/upea Alosa), the seminiferous tubes form innumerable ramifications and anastomoses in the substance of the testicle, easily discernible by the naked eye; and from the plexus thus produced ccecal tubes are prolonged to the sur- face of the organ, where they terminate by rounded extremities, giving the whole viscus, externally, a granulated appearance. (Fig. 204.) A few of the osseous fishes form remarkable exceptions to the usual mode of impregnation, the ova of the female being in such fecundated prior to their expulsion by actual copulation with the male ; and in some rare instances, as in the Blennins viviparus, the young are even produced alive, the ova being retained within the oviduct until they are hatched. In such cases the termination of the vas deferens swells into an external projection resembling a rudi- mentary penis, and, indeed, actually performing the office of an organ of intromission. In the more highly organized cartilaginous fishes, and even in some osseous genera, the structure of the generative system is entirely different, commencing that type which charac- terizes the reproductive organs of all the other vertebrate classes. In these the ovaria are not hollow sacs which have their cavity prolonged to the exterior of the body, but the ova are developed between layers of membrane sus- pended in the abdomen, which are unprovided with any canal immediately communicating with them. Such are the ovaria of the Eel and the Lamprey, which are formed of nume- rous festoons of delicate and vascular membrane suspended in front of the spine. The ova pro- duced between these membranous layers when mature break loose into the cavity of the abdomen, and are discharged through a simple orifice in the neighbourhood of the anus. In ORGANS OF GENERATION. 419 Fig. 204. Structure of the Testes in Clupea Alosa. this arrangement we have, therefore, the simplest form of the isolated ovaria of Reptiles, Birds, ond Mammalia, in alt of which the ova escape Jrom the surface of the ovary, not from its interior; and in the orifice through which the eggs are ultimately expelled from the abdomen we see the first rudiment of a Fallopian tube. In the Lamprey this orifice is prolonged into a short canal, and in Rays and Sharks assumes the form of an oviduct with which we shall afterwards see the Fallopian tubes of Mammals are identical; for whatever the complication which it afterwards assumes, the oviduct or Fallopian tube (for the two are the same in function) only receives the ova after their escape into the cavity of the abdomen to facilitate their ultimate expulsion. In Rays and Sharks the oviduct is double, commencing, however, by a fimbriated aperture common to both, which receives the eggs from the ovaria ; each oviduct is at first narrow and membranous, having its lining membrane longitudinally plicated, but before its termination the walls suddenly increase in thickness, developing in their interior a large gland destined to furnish the horny covering which invests the eggs of these creatures. Beyond the gland the oviduct expands into a capacious bag, which communi- cates with the cloaca. In this class of fishes the testis, like the ovary, is not hollow. In the Eel and Lamprey the secretion of the testis escapes from the external surface of the organ into the abdomi- nal cavity, whence, like the eggs in the females of the same tribes, it is expelled through a simple orifice provided for its egress. In these creatures the testis and ovarium are so entirely similar that they have been confounded by authors, the secreting granules in the one sex and the ova in the other being both disposed in regular laminae, and only differing inas- much as the testicular granules are smaller than the mature ova. The structure of the testis in Rays and Sharks is peculiar, these animals being appa- rently provided with both the kinds of testis above described. Each testicle consists of two portions quite detached from each other; the one is formed of an aggregation of globular masses as large as peas, from which no excre- tory duct has been found to issue ; the other is made up of convoluted canals, which, gradually uniting together, terminate in a capacious tube. The tuberculated mass has been described as the testis, while the convoluted tubes of the other portion were regarded as an epididymus, whence the vas deferens took its origin. There is, however, no communication between the granular part and that whence the vas deferens issues ; it is, therefore, probable that the former is analogous to the solid testis of the Eel and Lamprey, pouring its secretion into the abdo- minal cavity, whence it is emitted through the apertures well known to communicate in these creatures between the peritoneal bag and the exterior, while the latter is identical with the usual form of the testis in osseous fishes. TheBatrachian Reptiles in their mode of gene- ration, as well in so many other points of their economy, form the transition from the branchi- ferous to the pulmonary forms of theVertebrata, and hence the study of their sexual organs is ex- ceedingly interesting. The ovaria of these ani- mals in their entire organization resemble those of the Lamprey. Their size, however, is much in- ferior, and t'*e whole or^an exhibits a more con- centrated arrangement. The vascular membrane which forms each ovary is arranged in large folds on the sides of the spine, and the ova are deposited in great numbers between the lamellae of which it consists. The oviducts are long and tortuous, each commencing by a fimbriated aperture which is found to be situated at the side of the pericardium, and so bound down in that position by its peritoneal attach- ment-; thatwhen the interval which separates this point from the ovaria is considered, it is difficult to conceive how the ova, when dislodged from the nidus in which they were formed, can be brought into the oviduct; the only supposition, in fact, which will account for it is, that the eggs break loose into the abdominal cavity and thus make their way to the extremities of the oviducts. Before terminating in the cloaca the oviducts expand into capacious recepta- cles, in which the ova are collected prior to their expulsion, and glued together by a glairy secretion into masses which distend the whole of the abdomen. The ovaria of the Salamanders resemble those of the frog, as do the oviducts, but the membranous sacs which retain the ova are less considerable than in the Anourous Batrachia : the same observations apply to the perenni- branchiate orders. The structure of the testis in frogs is almost the same as that of the same organ in the cuttle-fish. If the investing tunic be removed, the whole substance of the organ appears com- posed of globules; but if these are gently sepa- 420 ORGANS OF GENERATION. rated, they are found to be merely the blind terminations of as many seminal tubes which run from the centre to the circumference of the testicle. The seminiferous ducts arising from Testis of Frog. these perforate the investing tunic of the kidney, upon which the testis is placed, and, according to Swammerdam, terminate in the ureters, which thus perform likewise the office of the vas deferens. We have carefully repeated Swammerdam 's dissection of these parts, which are represented at fig. 206. Fig. 206. Generative organs of Male Frog. a, Cloaca ; b, opening of genito-urinary canal ; c, opening of bladder into cloaca ; d, rectum; e, bladder ; /, testes, that of the right side in situ; g, kidneys; h, seminiferous tubes; i, tube serving both as ureter and vas deferens ; k, vesiculae seminales ; I, fatty appendages to the kidney. In other Amphibia the organization of the testis is essentially the same, but the seminal coeca, owing to their greater length, are tortuous and convoluted. The ova are impregnated in exitu by the aspersion of the seminal secretion of the male, who, firmly fixed upon the back of his mate, assists by his embraces the expulsion of the gelatinous masses in which the eggs are im- bedded. No organ of intromission, therefore, is required, and the generative ducts, both in the male and female, open by simple apertures into the cloaca. Nevertheless, in a few instances internal impregnation is effected ; such is the case with Triton, Laurent, in which, although no copulation takes place, the male fluid dif- fused through the surrounding water finds its way into the genitals of the female in sufficient quantities to secure fecundation. Moreover, in the Salamander f Lacerta Salamandra ) an intromission is accomplished, the male pos- sessing a rudimentary organ for that purpose ; in this latter case the eggs are even hatched in the oviduct and the young produced in the tadpole state. In the other reptiles the structure and arrangement of the generative organs is very similar; the same organization, in fact, exists through the whole class with slight modifica- tions adapted to the different forms or habits of different orders. Fig. 207. The testes are invariably double, placed symmetrically on the two sides of the body, and attached by membranous connexions to the vertebral column. On unravelling their inter- nal structure they are found to consist entirely of blind tubes enclosed in a membranous cap- sule; these seminiferous canals are much longer than in the amphibious tribes, and, conse- quently, present a tortuous arrangement, readily seen through the transparent covering of the testes (Fig. 207.) From these tubes a variable number of efferent canals proceed, which, after remaining for a short distance enclosed in a pro- longation of the tunics of the testicle, unite into a vas deferens, which is prolonged on each side to the cloaca, and there terminates at the root of the rudimentary penis. In the higher Reptilia impregnation is always effected internally, and the males are conse- quently provided with an organ of excitement, differing much in form, but invariably imper- forate, being merely grooved upon its surface by a channel, along which the semen flows into the cloaca of the female, but without any provision for its forcible expulsion. This kind of penis consists entirely of the corpora cavernosa, arising by two crura, ORGANS OF GENERATION. 421 which unite intimately along the upper aspect of the organ, but leave inferiorly a deep fissure which is continued to the extremity. In the Chelonia this organ of excitement is very large, and terminates in a single point, but in many Saurian and Ophidian species its extremity is bifid, each division being covered with sharp and recurved spines, an arrangement which, in creatures so deficient in organs of prehension, is evidently adapted to ensure efficient copu- lation. In the females of these reptiles the structure of the ovaria is interesting, gradually leading us from the folds of vascular membrane, between which the numerous eggs of the Batrachia are generated, to the form which they present in Birds. Each ovary assumes a racemose ap- pearance, and consists of a number of ova in various states of perfection, which are loosely attached to the sides of the vertebral column by folds of peritoneum. Their structure, however, is essentially that which has been already de- scribed, and the ova, when matured between the vascular lamina; of the ovarian investments, escape, as in frogs, from the surface of these viscera by a laceration of the investing mem- brane, and would break loose into the abdo- minal cavity did not the more perfect develope- ment of the oviducts, which here have their patulous extremities so disposed that they can grasp the ovaria during excitement, prevent such an occurrence, by receiving the germs imme- diately from the ruptured ovary. The oviducts are two in number, membranous at first, but glandular as they approach their termination in the cloaca. In these the eggs receive an albuminous investment which they absorb in the first portion of the canal, and prior to their expulsion are furnished with a coriaceous or cal- careous covering produced from the thicker portion of the oviferous tube. The females of the Cliclonia have a clitoris, or rudiment of the male penis, which is in a similar manner provided with muscles for its retraction into the cloaca after extrusion. In other Reptiles the clitoris is deficient. Birds form a remarkable exception to the usual arrangement of the internal sexual organs in oviparous vertebrate., the ovarium and oviduct being single throughout the class, an organi- zation which is evidently in relation with that lightness and activity essential to their habits. This deviation from the usual type, however, is only apparent, arising from the non-develop- ment of the ovary and its duct on one side of the body, although both exist in a rudimentary state. The ovarium, as in Reptiles, is racemose, consisting of ova in different stages of growth, each enclosed in a vascular membrane, which forms a pedicle attaching it to the general cluster, and is ruptured by the escape of the germ enclosed within it. The oviduct is short in comparison with that of many reptiles, and the structure of its lining membrane indicates the offices performed by different portions of the canal, being smooth and vascular in its upper portion, where the yolk receives its albuminous covering, but becoming villous and plicated where it secretes the shell. Male birds, like reptiles, are furnished with two testes, which, from their comparatively in- significant size, do not materially interfere with the bulk of the viscera; yet even these only as- sume their full proportions at stated times, namely, at that period of the year when their office is required. The testes are constantly situated in the ab- dominal cavity immediately behind the lungs and under the anterior extremity of the kidney : as in all cases, they consist of sperm-secreting tubes, but of such extreme tenuity that their diameter was estimated by Muller as not greater than the 0 00528 of a Parisian inch. These canals are enclosed in a proper capsule, which sends septa into the interior of the organ; they unite to form a slightly flexuous vas defe- rens, which accompanies the ureter of the cor- responding side. The vasa deferentia termi- nate by separate orifices in the cloacal cavity near the root of the rudimentary penis when such exists, but even in its most perfect forms the male organ is merely an instrument serv- ing for the conveyance of the seminal liquor along a groove seen upon its surface, there being as yet no corpus spongiosum or inclosed urethra as in the Mammiferous classes, adapted to an efficient injection of the semen into the female parts, nor any auxiliary secretions sub- servient to the same purpose. In the females of those genera in which the penis is most de- veloped, a clitoris is found to occupy a similar position. The Mammalia differ remarkably from the other vertebrate classes in the elaborate deve- lopement of the sexual organs in both sexes. The increased complication of these parts is attri- butable in the male to the necessity for a much more efficient intromission of the spermatic secretions during coitus, and in the female to the superadded function of gestation which characterizes the class. On comparing the male organs of Mammi- fera with those of the oviparous vertebrata, several circumstances demand our notice, the most striking of which is the separation of the canals provided for excretion into two distinct systems, each terminating externally by an appropriate orifice, thus detaching entirely the digestive emunctory from the genito-urinary apparatus, which hitherto we have found to dis- charge themselves by one common orifice com- municating with a cloacal cavity. With one interesting exception furnished by the Mono- tremata, such a separation exists throughout all the Mammiferous orders. Internally a still further isolation is evident in the separation of the urinary and generative organs by the pro- vision of a urinary bladder, in which the secre- tion of the kidneys is stored up until its expul- sion becomes necessary ; the same excretory canal, however, is still common to both these systems. In the ovipara the penis was merely furrowed with a sulcus, along which the semen trickled during the union of the sexes without being impelled by any expulsive apparatus ; but in the class of which we are now speaking the urethral canal becomes surrounded by vas- cular erectile tissue, forming a complete tube through which the seminal liquor is powerfully 422 ORGANS OF GENERATION. ejaculated during copulation by a muscular arrangement provided for that purpose ; and in the last place the emission of the fecundating fluid is further provided for by the addition of secondary secretions, which from augmenting its quantity facilitates its ejection. We shall proceed to speak of these circum- stances seriatim, examining first, the structure and position of the testis and its duct; secondly, auxiliary glands which add their secretions to the seminal liquor; thirdly, the structure of the penis, and arrangement of the organs of intro- mission. We have found in all the classes of verte- brata of which we have hitherto treated, that the testes consisted essentially of blind tubes. In Frogs these sperm-secreting canals were ex- ceedingly short; in other Amphibia they become elongated and flexuous. In Reptiles their length and convolution was still further in- creased, until at length in Birds and Mamma- lia their length is so great, and their delicacy so excessive, that they are with difficulty unra- velled. In all animals the terminations of the seminal tubes are found to be closed, neither is any increase or diminution perceptible in the diameter of one of these vessels throughout its whole course. Another circumstance which, with one or two exceptions, is common to all Mammals, is that they never ramify or divide.* Mammalia differ much amongst each other as regards the length, number, convolutions, and general arrangement of these secerning vessels of the testis. In the Ass they are very delicate; of greater diameter in the Cynoce- phalus and larger Carnivora, as well as in the Hog and Rhinoceros. They are very large in the Glire$, and in Sciurus their diameter reaches -0-01453 inch (Paris), whilst in the Hedgehog they are only 0-00970 inch. The tenuity of the walls of these seminal vessels is extreme, and scarcely applicable by the micrometer ; they are united together by a most delicate tissue of capillary bloodvessels, serving to imbue them with that blood from which the semen is separated, which when se- creted accumulates in the cavities of these tubes in readiness for expulsion. The testes are very variously situated in the adult state of different mammals. Sometimes they are contained within the abdominal cavity, attached on each side of the spinal column by folds of the peritoneum, as in the ovipara ; at other times they descend into the skin of the groin through the inguinal canal, and not un- fiequently are contained in a scrotal pouch formed by the integument behind the pubic arch ; and in the Marsupial division, which, when describing the female sexual organs, we shall find to constitute a distinct type of the generative system, they are suspended in front of the pelvis. The excretory duct of each testis or vas de- ferens is formed by the junction of the seminal canals of the testis ; it is at first much convo- luted, forming a mass appended to the testicle, denominated the epididymus ; and whatever * In Sciurus they have been observed to divide dichotomously. may be the position of the testicle, it runs to discharge itself into the canal of the urethra near the commencement of that tube. The prostate gland is a secreting- body of pe- culiar structure, which, in man, embraces the neck of the bladder, and opens by ten or twelve ducts into the urethra near its commencement. It is very constant in its existence, being found in all orders of Mammalia, excepting, perhaps, the greater number of the Rodentia, the Mole, and the Hedgehog, in which it is apparently replaced by secerning organs of a widely dif- ferent structure; otherwise, the internal organi- zation of this gland is nearly the same in all animals that possess it, consisting essentially of cells, each of which is subdivided into others of extreme minuteness. From these cells the excretory ducts take their rise, and the whole organ may be readily inflated by forcing air into the canals which issue from it : the whole is enclosed in a dense fibrous capsule. In some animals, as the Elephant and Solipeds, the prostate is double or even quadruple, and in this case the centre of each portion has within it a large cavity which communicates with the smaller cells, and gives origin to the excretory tube. Coivpers glands. — These glands in the hu- man subject are two very small bodies situated behind the bulb of the urethra, which furnish minute canals, opening obliquely into the urino- generative canal near its posterior portion ; but minute as they are in man, they are found in other creatures to be much more voluminous, net unfrequently equalling the prostate in size, and in some cases, especially in the Marsupial division, they are increased in number ; thus in the Opossums and Kangaroo-rat there are four, while in the Wombat ( Fhascolomys), the Kangaroo, and others, even six are found : nevertheless in most of the Carnivora, except the Felidae and Hyenas, and in the greater number of Ruminants, Solipeds, Amphibia, and Cetacea, they are deficient. The internal structure of Coivpers glands varies. In man and many others they are composed of simple follicles ; in other cases, as in Sciurus, the Marmot and the Hog, they consist of conical sacculi, which exhibit in- ternally a cellular appearance. In the Beaver (Castor Fiber ) their texture is spongy, being formed of large cells, divided by septa into smaller ones of extreme minuteness ; those of the Mole are similarly constructed. In Vi- verra Zibetha, the feline tribes and the Hyena, they are made up of separate lobules ; and in the Ichneumon these glands are composed of vesicles united by a common duct. In the Hedgehog ( Erinaceus Europceus) they are found in a very singular position, being partly situated beneath the rami of the pubis and ischium, and partly beneath the skin on the inner side of the thigh, being so remote from the other glands that their existence was over- looked by Cuvier. Each gland consists of pyramidal lobules, which, by their apices, give rise to the excretory canals. In some of the Marsupiata their minute structure resembles what is found in the Hedge- hog; and each of them is surrounded by a ORGANS OF GENERATION. 423 powerful muscular sheath, calculated to en- sure the expulsion of tha fluid which they elaborate. The most remarkable arrangement cf Cow- per's glands is seen in the Ichneumon ( Her- pestes Ichneumon, Illiger): in this animal they are very large and occupy their usual position, being invested with v. strong muscular coat; but their excretory ducts, instead of termi- nating as usual in the bulbous portion of the urethra, are prolonged beneath the penis nearly to the extremity of that organ, where they open into a cul-de-sac common to them and the canal of the urethra. Accessor!/ vesicles. — These are auxiliary glands, which pour their secretions into the canal of the urethra. They appear, when present, to take the place of the prostate, being only found where that organ is deficient, and accordingly, although of a totally different structure from that body, they have been called prostates by various authors. They are usually packets of membranous cceca, more or less ra- mified, and in the season of sexual excitement are filled with a fluid resembling that contained in the vesiculae seminales. These organs exist in all Rodents except Squirrels, Marmots, and Hares, and also in the Hedgehog and the Mole, but have not been found in any other mammalia. They are invariably composed of intestinules or branched cceca, arranged in packets, the number of which varies much. Thus ia the Mole there are five such bundles, forming a mass of ramified tubes larger than the bladder ; in the Hedgehog there are four, and in Cricetus vulgaris and Dasyproeta Aguti two fasciculi. But besides the secreting structures above enumerated as forming the ordinary appendages to the male generative system of Mammifers, additional ones are occasionally found, placed out of the positions in which the succenturiate glands usually exist. Thus in Solipeds a long ccecum containing a glairy fluid is placed be- tween the insertions of the vasa deferentia, which communicates with the urethra by an appropriate orifice; and in Cricetus and manv of the Murida: the ends of the deferent canals before their termination are provided with bunches of small glandular follicles, which in the former resemble small bunches of grapes. The annexed figure, (fig. 208,) representing the male generative viscera of the Hat ( Mus liattus) exhibits an example of the greatest com- plication of these parts, and will serve to illus- trate the situation of the organs above described. A represents the bladder turned forwards, B the rectum, and C the testis of the left side. The succenturiate glands here found are a, a, the vesiculic seminales ; b, the anterior fasciculus of the accessory vesicles or anterior prostate of some authors, which on the opposite side is un- ravelled to display the cceca which compose it; c, the middle prostatic cceca; d, the anterior prostatic cceca. These all communicate with the urethra, and in addition to these we have on each side the racemose bunch of follicles (e) which is appended to the termination of the vas deferens ( /'). Structure of the penis. — The great difference between the penis of Mammifers and that which has been described as existing in the oviparous vertebrata, consists in theinclosure of the canal of the urethra, which is no longer a simple groove formed by the junction of the corpora cavernosa, but becomes surrounded with a cy- linder of erectile tissue usually denominated the corpus spongiosum urethra. The corpus cavcrnosum, which generally forms the great bulk of the organ, arises by two crura, which are firmly attached to the rami of the ischium in the males of all placental Mammalia; and even in the Cetacea, where there is no pelvis, two bones placed on each side of the corpus caver- nosum give a support to the penis, which is attached to them by fibrous ligaments ; never- theless, in the Marsupiata the crura of the corpus cavernosum are quite free, or only loosely attached to the ischiadic bones by the muscular sheaths in which they are en- veloped. The crura of the corpora cavernosa unite to form the body of the penis, their union being generally marked by a strong septum, which more or less completely divides the organ into two lateral halves. In some animals, as in the Dog, this septum is very distinct ; but in other cases, especially in many of the Plantigrade Carnivora and in most of the Pachydermatous and Cetaceous tribes such a partition is entirely wanting; in such cases the fibrous lamellae, which arise from the dense capsule surrounding this portion of the penis, and traverse the vascular tissue which is con- tained in its interior, unite at a central- part in a kind of cord formed by their union. In some anima's the organ is supported by a bone developed in its interior: this arrangement exists in the Quadruniana, Cheiroptera, the lJluntigrade and Digitigrade Carnivora (ex- cept the Hyaena), and in the Rodentia, also in Seals and Cetaceans. In a few instances it is so large as to form a large portion of the penis, as in Whales ; in others, as in many Carnivora and Rodentia, it is extremely small, but what- ever its form or size it is invariably found in- timately connected with the corpus caverno- sum. The urethra, as in man, consists of a mus- cular and of a vascular portion, the former receiving the ducts of the succenturiate and 424 GENERATION. seminal glands, the latter embedded in the erectile tissue of the corpus spongiosum. The muscular portion does not always join the vas- cular part in a straight line ; but, on the con- trary, in some animals, as in Ruminants gene- rally and in the Boar, the former opens by an orifice perforated in the upper wall of the latter, at a little distance from its commence- ment, so that a c ul-de-sac is left excavated in the bulb of the urethra or commencement of the spongy portion, in which the fluids poured into the muscular part are mixed with the se- cretion of Cowper's glands, which enters the sides of the excavation. In Squirrels and Marmots a similar cul-de- sac exists, which only receives the secretion of Cowper's glands, and is continued forwards as a narrow tube surrounded by vascular tissue, beneath the urethra, as far as the middle of the penis, where the two canals unite. The course of the urethra in the great Kan- garoo ( Macropus major) is peculiar; instead of passing, as is usually the case, beneath the corpus cavernosum, it is inclosed in a canal passing through the centre of the penis, from which it only emerges at the extremity of the glans ; owing to this arrangement, the spongy investment of the canal is in this animal con- founded with the vascular tissue of the corpus cavernosum. In others of the Marsupiata the corpus spon- giosum, like the cavernous body, arises by two crura, which are quite unattached, each being invested with a strong muscular sheath, and even in some placental Mammals, as the Water- rat and the Camel, rudiments of this division are distinguishable. The glans penis, or extremity of the intro- mittent organ, presents many modifications in form and in the nature of its surface. It is frequently smooth and highly sensible, as in man, being only covered by a delicate skin ; yet in other instances, as in the feline Carni- vora, it is armed with stiff recurved bristles ; sometimes the armature represents horny scales or strong spines, and in not a few genera we find horny serrated plates projecting from its surface; and, as though these formidable saws were insufficient, they are occasionally com- bined with horny prongs protruded from the extremity of the penis during its erection. These last appendages are found in various families of the Rodentia, as in Guinea-pigs and Agoutis. The limits of this article will not permit us to expatiate further on this part of our subject; we must therefore refer the reader for a description of the various forms of the penis and of the muscles belonging to that organ to the articles which treat of the Mam- miferous orders individually. The female Mammalia exhibit in their gene- rative system a beautiful gradation of struc- ture. They naturally divide themselves in conformity with their mode of gestation into two classes, viz. the Ovo-vivipara or Marsu- piata, and the Viviparu, properly so called, comprising the placental orders. The former division approximates in every particular to the oviparous type of structure : the ovaria are racemose, as in birds; the ovi- ducts, which now assume the name of uteri, are still double, opening by distinct orifices into the vagina, which also is not unfrequently di- vided. But the great feature which distin- guishes the ovo-viviparous mammals is the peculiar apparatus in which gestation is com- pleted, the embryo being expelled from the uterus at a very early period, without ever con- tracting any vascular connexion with that organ, to be lodged in a marsupium or pouch con- nected with the abdomen of the mother, in which the nipples are contained. In this situ- ation it becomes attached by its mouth to one of the teats, and thus derives from the mam- mary secretion the nourishment essential to its growth. — See Marsupiata. In the Placental division gestation is com- pleted within the uterine cavity by the deve- lopment of a vascular mass of different con- struction in different classes, called the Pla- centa. The ovaria here gradually lose their racemose appearance, and are converted into small and solid masses, in which the ova or Graafian vesicles are evolved. The uterus, at first completely divided, as in some of the Rodentia, in which the two cornua open se- parately into a single vaginal canal, by degrees unites, and by a progressive coalescence attains that concentration most perfectly exhibited in the human female. To enter more largely into details connected with the generative organs of the Mammiferous classes would needlessly swell the bulk of this article, in which our object has been to lay before the reader a connected view of the mo- difications met with in the reproductive system throughout the animal kingdom, and thus to connect with each other the numerous facts relating to this subject which are elsewhere more minutely recorded in this work. For the anatomy of the Organs of Generation in Man, see PENIS, PROSTATE, TESTIS, VESlCUL^E SEMINALES. ( T. Rymer Jones.) GENERATION (in Physiology) generatio; Fr. generation; Germ. Zeugung ; Ital. gene- razione;) is the process by which the young of living bodies are produced, and their spe- cies continued. In common language the term is frequently confined to the mere act of union of the sexes of animals; but in general and animal physiology it is generally employed in the more extended signification given to it in the following article, viz. to denote the assem- blage of all the functions of animals concerned in the formation of their young, and as syno- nymous, therefore, with the function of Repro- duction. In directing our attention to the mode in which the function of reproduction is effected in various classes of animals, so many striking differences present themselves, that we find it difficult if not impossible to point out any general circumstances in respect to which they all agree. Some animals, for example, are propagated by the division of their whole bodies into pieces, each of which by a pecu- GENERATION. 425 liar change becomes an independent individual entering upon a new life. Others arise like the parts of a tree by buds which remain for a time attached to the parent stem, and being afterwards separated from it assume an inde- pendent existence. A third class of animals have the power of forming and throwing off from their bodies a small portion of organized matter, which, though at the time of its sepa- ration from the parent, not resembling it either in form or organization, is yet possessed of the power of living for itself, and, after passing through a variety of successive changes of growth and evolution, of at last acquiring the exact semblance of the parent by which it was produced. In a fourth and last class, com- prehending much the greatest number of ani- mals, the function of reproduction involves a greater complication of vital processes than in the three other classes above alluded to. The union of two individuals of different sex be- comes necessary, and the young owe their origin to the evolution of a more complex organized structure termed the egg, which is formed in and separated from the body of the female parent, and is the product of the union of the male and female of all animals in which the distinction of sex exists. The ovum or egg is most familiarly known to us in the eggs of domestic birds, to which the product of sexual union in all animals belonging to this fourth class bears a strict analogy in every essential particular. It may be stated as a general fact, that the reproductive function involves a greater num- ber of vital processes in the higher and more complicated than in the lower and simpler kinds of animals. Yet there are exceptions to this rule, and we do not always trace a correspondence between the degree of com- plication of the generative process of any animal and the place which that animal holds in the scale of being ; for there are some tribes of animals which are propagated in more than one of the ways above mentioned, and there are some, to which, from the simplicity of their other functions and organization, a low place in the zoological scale has been assigned, and which nevertheless resemble the higher animals in respect to their mode of reproduction. A very superficial view, however, of the vari- eties of the form obvious in the reproductive process of different animals demonstrates the importance of the reproductive functions in the economy of life, as it points out the intimate relation which these functions bear to the habits, mode of life, and organization of each animal, and shews the infinite care and fore- sight with which nature, in every variety of circumstance, has provided for the regular and undisturbed performance of those acts by which the species of organize 1 beings are con- tinued from age to age, in an undeviating suc- cession of generations. These facts also fully justify our regarding, along with Cuvier, the reproductive function as constituting one of the fundamental divisions in a classification of the processes of the animal economy. While, therefoie, the principal object of the VOL. II. present article is to describe the process of generation in Man and the higher Vertebrated animals, it will be necessary and proper for us to allude also to the reproductive function as it is performed in all the various members of the animal series ; for in this, as in other de- partments of Physiology, the more complicated forms of the process derive much illustration from the study of the more simple, and we may hope thus more fully to point out the general importance of the functions now under consideration. We purpose to follow an arrangement adapted chiefly to the consideration of Human Generation. In all the animals in which dis- tinction of sex subsists, the male and female organs subservient to reproduction must co- operate for the completion of the generative process; and in the greater number of the more perfect animals, as also in Man, the two kinds of sexual organs being placed on separate in- dividuals of the same species, the concurrence of both these individuals, or of both male and female parents, is necessary for the for- mation of the fruitful products from which the offspring proceeds. The circumstances, then, which give rise to the union of the sexes and the phenomena which accompany that union, form some of the topics of the present article. The product of fruitful sexual union in all animals is one or more eggs, from each of which, under the influence of certain favourable circumstances, different in different tribes, the young animal is produced by an intricate pro- cess of vital growth. The greater part of the substance composing the egg is furnished by the female parent : but this egg of the female would be wholly barren, or would not undergo any of those changes by which the young animal is formed, unless it received irfsome way or other the influence of the product of the generative organs of the male ; and the egg formed by the female may be regarded as im- perfect until the change now alluded to has been effected in it. It is then said to be fecundated or rendered fruitful by the semen of the male. The mode of formation of the egg and seminal matter, the mode of their separation from the place of their formation, the structure and properties of each of these products, the manner in which they are brought together, the influence which they exert upon one another, and the consequent result in the production of the young, con- stitute the principal remaining topics which fall to be discussed by us at present. In this article our attention must chiefly be confined to such operations or functions of the male and female parents as are preliminary to or necessary for the formation of a ripe and fruit- ful ovum, — that is, an egg capable of giving birth to a new animal the same as either of its parents, when placed in those circumstances which are favourable to its evolution. It is not intended to speak in this place of the changes of the ovum itself in which the for- mation of the young animal consists : the consideration of these is reserved for the article Ovum. 2 F 426 GENERATION. Before treating in detail of Human Gene- ration, we introduce some remarks on the nature of the reproductive function in general, and a sketch of the principal varieties of the forms it assumes in different classes of ani- mals. I. THE FUNCTION OF REPRODUCTION GENE- RALLY CONSIDERED. 1. Introductory remarks. — The process by which the young of animals are formed has, from the earliest periods of science, always been an object of peculiar interest and atten- tion to inquirers into the functions of animated beings. Scientific men as well as the more ignorant have looked with a mixed feeling of wonder and admiration upon the intricate changes which precede and accompany the first appearance and gradual formation of all the different textures and organs belonging to animal bodies. The gradual construction or building up of the whole frame-work of the animal body, and its various important organs, — the formation of the nerves and brain that feel and think, the muscles that move, the blood with its containing organs that propel it and apply it to the purposes of nutrition, — the appearance step by step of all the remark- able structures out of which the different organs are formed, — the development of the appropriate vital powers of each of them, — the comparatively simple structure of the sub- stance of the egg, and the impossibility of detecting in it by the most exact scrutiny, before the commencement of the formative process, any appearance of the parts after- wards arising there — have naturally led phy- siologists to inquire minutely into the pro- perties of that egg, and the process by which so remarkable a production is generated. The ascertained fact that the egg possesses vital powers belonging to itself, and that its life is in a great measure independent of that of its parents, — that the vital powers of the egg are capable of being called into operation and in- fluenced in many animals by determinate external physical agents, such as heat, air, light, and electricity, — the obscure nature of the influence exerted by the male upon the female product in the perfecting of the egg, — the preservation of the specific distinctions of animals from one generation to another in un- deviating succession, — the transmission of oc- casional varieties or peculiarities of form and of hereditary resemblances from parent to offspring, — and, in fine, the important relation which the generative process bears to other functions of the animal economy, are among the more prominent circumstances which, while they throw a certain air of mystery over the functions of reproduction, have at the same time given them an interest in the eyes of the physiologist, which increases as his acquaint- ance with their details becomes more ex- tended. It is a common remark that generation is at once the most obscure and the most wonderful of the processes occurring in organized bodies. Hence, perhaps, it has happened that,while there are few subjects of physiological inquiry upon which so many authors have written, there is none upon which so many have freely indulged their fancies in framing unwarranted hypotheses and absurd speculations. This is an error which belongs to the early stage of investigation in most branches of natural knowledge, and which in the instance before us may be traced very directly to the comparative want of cor- rect information which for a long time pre- vailed regarding the phenomena of the gene- rative processes. For, if we except the re- markable investigations of Aristotle, Fabricius, Harvey, Malpighi, Wolff, and Haller, it may be said that it is only towards the conclusion of the last or the commencement of the pre- sent century that our subject has been studied with that accuracy of observation and freedom from hypothesis which are calcu- lated to insure steady progress in the attain- ment of physical knowledge. When ex- tended observation shall have rendered more familiar to the physiologist the different steps of the intricate processes by which an egg is formed and the young animal is developed from it, although he may not cease to admire the changes in which these processes consist, the feeling of wonder will be in a great mea- sure lost to him ; and he will not be inclined to look upon the gradual formation and growth of the child as more extraordinary than the constant and regular nutrition of the fully formed body. Are the inscrutable workings of the brain and nerves, the constant energy of the beating heart, the unwearied and pow- erful exertions of the voluntary muscles, the secretion of different fluids from the glands, and the regular supply of suitable organic materials to all parts of the body, so as to maintain the healthy structure of each and fit them for the performance of their respective offices, less remarkable and astonishing, or, in other words, less far removed from our accurate knowledge and comprehension, than the first origin and early growth of the same organs at a time when both their structure and functions are greatly more simple? Certainly not. These remarkable changes are all objects of wonder to the vulgar in proportion as they are unknown. The man of science regards the ultimate cause of all vital processes as equally inexplicable, and, aware of the bounds set to his knowledge of life, limits his inquiries con- cerning its various processes to the investigation of their phenomena. At the same time it may be allowed that the fact that the mere contact of the male seminal fluid seems to awaken and call forth from the otherwise inanimate egg all those vital powers which are afterwards concerned in sustaining the life of the new being, is one of the most striking and simple examples of vital agency, and one less suited than most others to be observed or experimentally investigated. The theoretical physiologist, in contemplating this fact, is apt to conceive that here he has ar- rived at one of tbf primitive causes or foun- dations of animal ! fe, and that he has here obtained the key; many of its hidden won- GENERATION. 427 ders : he passes the limits which ought to - bound his inquiries, and in most instances invents fanciful and curious speculations rather than makes sound generalizations of ascer- tained facts. 2. Theories of generation. — The vast num- ber of the theories of generation renders it impossible to mention even the more im- portant in this place. Drelincourt, an author of the last century, brought together so many as two hundred and sixty-two " groundless hypotheses" concerning generation from the writings of his predecessors, " and nothing is more certain," quaintly remarks Blumenbach, " than that Drelincourt's own theory formed the two hundred and sixty-third."* Of these theories two principal classes may be distinguished, according as they more di- rectly relate, 1st, to the action of the parent organs, or 2d, to the changes in the egg belonging to the formation of the new animal. Of the first of these classes of theories Haller made three divisions, according as the offspring is supposed to proceed, 1st, exclusively from the organs of the male parent, 2d, entirely from those of the female, or 3d, from the union of the male and female products. The second class of these theories, that, viz. which relates more particularly to the formation of the new animal, may be arranged under two heads, according as the new animal is supposed, 1st, to be newly formed from amorphous materials at the time when it makes its appearance in the egg, or 2d, to have its parts rendered visible, by their being expanded, unfolded, or evolved from a previously existing though in- visible condition in the germ. The greater number of the older theories of generation may then be brought under one or other of the above-mentioned divisions, viz. the theory of the Ovists, of the Spermatists, that of Combination, Evolution or Epigenesis. According to the first-mentioned of these hypotheses, or that of the Ovists, the female parent is held to afford all the materials neces- sary for the formation of the offspring, the male doing no more than awakening the forma- tive powers possessed by, and lying dormant in, the female product. This was the theory of Pythagoras, adopted in a modified form by Aristotle ; and we shall afterwards see that it resembles most closely the prevailing opinion of more modern times. The terms, however, in which some of the older authors expressed this theory are very vague, as, for example, in the notion that the embryo or new product " is formed from the menstrual blood of the female, assisted by a sort of moisture descend- ing from the brain during sexual union." According to the second theory, or that of the Spermatists, among the early supporters of which Galen maybe reckoned, it was supposed that the male semen alone furnished all the vital parts of the new animal, the female organs merely affording the offspring a fit place and suitable materials for its nourishment. * See Blumenbach uber den Bildungstrieb,12mo. Gotting. 1791. Anglice by A. Crichton : An Essay on Generation, 12mo. Lond. 1792. Immediately upon the discovery of the seminal animalcules, these minute moving particles were regarded by some as the rudiments of the new animal. They were said to be miniature representations of men, and were styled ho- munculi, one author going so far as to delineate in the seminal animalcule the body, limbs, features, and all the parts of the grown human body. The microscopic animalcules were held by others to be of different sexes, to copulate, and thus to engender male and female off- spring; and the celebrated Leeuwenhoek, who was among the first to observe these animal- cules, described minutely the manner in which they gained the interior of the egg, and held that after their entrance they were retained there by a valvular apparatus. The theory of Syngenesis or Combination seems to have been applied principally to the explanation of reproduction of quadrupeds and man, the existence and nature of the ova of which were involved in doubt. This hypothesis con- sists in the supposition that male and female parents both furnish simultaneously some semen or product ; that these products, after sexual union, combine with one another in the uterus, and thus give rise to the egg or structure from which the foetus is formed. In connexion with this theory we may also mention that of Meta- morphosis, according to which a formative substance is held to exist, but is allowed to change its form in order to be converted into the new being ; as also the notion of Buffon that organic molecules universally pervade plants and animals, that these are all endowed with productive powers, that a certain number are employed in the construction of the textures of organized bodies, and that in the process of generation the superabundant quantity of them proceeds to the sexual organs and there consti- tutes the rudiments of the offspring. The theories of generation proposed before the commencement of the seventeenth century are either unsatisfactory or erroneous from the entire want of accurate knowledge prevailing before that time regarding the relation of the egg to reproduction. The conversion of one animal into another, constituting equivocal or spontaneous generations, was very generally believed in ; and the process of the formation of the egcr was equally ill understood in the lower and higher classes of animals. It was in the course of the seventeenth century that the labours, first of Harvey, and afterwards of Swammerdam, Redi, Malpighi, De Graaf, and Vallisneri, gave rise to greater precision of knowledge and opinions regarding this subject, and finally established the Harveyan dictum, " omne vivum ex ovo," which may be regarded as the starting - point or basis of modern researches. The theories of generation seem after the period of Harvey to have changed somewhat their object, and to have been directed more exclusively to the explanation of the formative process, or the manner in which the parts of the foetus are first formed in the egg and after- wards attain their ultimate structure and con- figuration. 2 f 2 428 GENERATION. It was then that the foundation was laid for the discussion between Epigenesis and Evolu- tion, the two theories of generation which have more recently occupied the attention of men of science, and which, as has already been remarked, relate principally to the nature of the formative process. Harvey and Malpighi may be regarded as the first who endea- voured, from the observation of facts, to establish the general law of Epigenesis as opposed to the older views of Preformation entertained by the Ovists or Spermatists ; but it was not till near the middle of the last century that these opinions were opposed to one another in a decidedly controversial manner. At that time Caspar Frederick Wolff* sup- ported the system of Epigenesis by a reference to observations on the minute changes of the egg of the fowl during the early stages of formation of the chick, while Haller and Bonnet advocated the opposite opinion of Evolution. Wolff and those who followed his system held that no appearance of the new animal is to be found in the perfect impregnated egg before the commencement of incubation, but that when the formative process is established by the influence of heat, air, and other circum- stances necessary to induce it, the parts of the foetus are gradually put together or built up by the apposition of their constituent molecules. Hallerf referred both to his own observations on the chick and to a variety of collateral arguments in support of the system of Evolu- tion, holding that when the foetus makes its appearance in the egg, it does so merely in consequence of the enlargement or evolution of its parts which pre-exist, though in an invisible condition, in the egg. Bonnet} carried this theory further than any one else, but trusting mainly to the observations of Haller on the formation of the foetus, he supported his overdrawn views on highly hypothetical reason- ing. Bonnet, in what is termed the theory of Emboitement, held not only that the whole of the parts of the foetus pre-exist in the egg before the time of their appearance, but also that the germs of all the animals which have been or are to be born pre-exist from the begin- ning in the ovaries of the female ; that the genital organs of the first parents of any species, therefore, contain the germs of all their pos- terity ; that these germs lie dormant in their abode until one or more are aroused by the exciting influence of the male; and that con- sequently there is not in nature the new forma- tion of any animal. We shall have occasion to shew in the article Ovum that the most recent researches concern- ing the mode of formation of the foetus in birds, quadrupeds, and other animals, and more particularly the microscopic observations * Theoria Generationis, published as an Inaugu- ral Dissertation at Berlin in 1759, and republished jn 8vo. in 1774. t Elementa Physiologiae, &c. torn. vii. Mem. sur la formation du Cceur dans le Poulet. Lau- sanne, 1758, Opera Minora, torn. ii. f Palingenesie Philosophique, Geneve, 1769 ; also in his Considerations sur les Corps Organises. of Meckel, Pander, Baer, and Rathke,* have shewn the theory of Epigenesis or super- formation of parts to be much more consistent with what is known from observation than the theory of Evolution. In modern writings, however, the term Development is, without reference to theory, employed to denote the mode of growth of the foetus more frequently than any other. We would further remark in relation to our present subject that various names have at different times been given by authors gene- ralizing the phenomena of development to the powers supposed to operate in the formation of the young ; as, for example, the Anima vege- taliva, Nisus J'ormativus, Vis plastica, Vis essentialis, expansive, resisting, and vegeta- tive forces. These terms can be considered as little else than general expressions of the fact that the foetus is formed and grows in the egg, and are not more satisfactory expla- nations of the cause of its formation than the hypothesis of organic affinity is of the process of assimilation in the adult animal. As the knowledge of minute anatomy and physiology has increased, and the accurate observation of the process of developement has been more extended, the number of such hypotheses has gradually diminished. Thus the somewhat vague discussion as to the relative probability of Epigenesis and Evo- lution has led to the laborious and accurate investigation of the various steps of the forma- tive process or developement of the foetus, and the conjectures as to the forces or causes which give rise to the growth of the new animal have fallen into comparative neglect; the erroneous notions respecting the source of the germs of male or female offsprings from one or other ovary or testicle have been replaced by a more satisfactory examination of the mode of deve- lopment of the sexual organs in the early stages of their advancement; and the inquiry as to the share taken by one or other parent in the process of generation has been pursued in more modern times by the attentive investigation of the functions of the male and female organs of reproduction, upon the same principles that guide the physiologist in his attempts to explain any other class of functions of the economy. Recent writings on our subject are not, how- ever, altogether free from vague hypotheses of the same nature as the older theories of gene- ration above mentioned. The mechanical explanation of fecundation by the entrance of the seminal animalcule into the egg has been revived by one author; a second considers all the changes of development as under the influence of electro-magnetic currents ; and a third explains the same changes by attributing them to a spontaneous motive power and organic affinitive properties of the molecules of the ovum. It has been well remarked by Professor * After these observers may be mentioned Serres, Prevost and Dumas, Dutrochet, Rolando, Purkinje and Valentin, Coste, and otheis, as contributing materially to the knowledge of this subject. GENERATION. 429 Burdach that the generative function, com- prising the production of a fruitful egg and the formation of the young animal from it, are natural phenomena not more secret in their essence than others occurring in organized bodies, and which, therefore, ought to be investigated by obtaining a knowledge of the conditions in which they take place, and of the operations and changes in which they consist. The illustrious Harvey in his 51st Exercita- tion expresses himself thus decidedly a sup- porter of the theory of Epigenesis, — " it is plain that the chicken is built up by Epigenesis or the additament of parts budding one out of another;" but he does not admit that separate powers, such as the "alterative or immutative, formative, attractive, retentive, digestive, and expulsive faculties, or those of apposition, agglutination, and assimilative nutrition de- scribed by Fabricius," can be distinguished in the production of the chicken. He thus limits our knowledge of the subject in the 54th Exercitation : " But as in the greater world we say Jovis omnia plena, all things are full of the Deity, so also in the little edifice of a chicken, and all its actions and operations, digitus Dei, the finger of God or the God of nature doth reveale himself." " A more sub- lime and diviner artificer (than Man is) seems to make and preserve man ; and a nobler agent than a cock doth produce a Chicken out of the egge. For we acknowledge our omnipotent God and most high Creator to be every where present in the structure of all creatures living, and to point himself out by his workes ; whose instruments the cock and hen are in the gene- ration of the chicken. For it is most apparent, that in the generation of the chicken out of the egge, all things are set up and formed, with a most singular providence, divine wisdom, and an admirable and incomprehensible artifice." " Nor can these attributes appertain to any but to the Omnipotent Maker of all things, under what name soever we cloud him ; whether it be the mem divina, the divine mind with Aristotle, or anima mundi, the soul of the universe with Plato; or with others natura nuturans, Nature of nature herself; or else Saturnus or Jupiter with the heathen, or rather as befits us, the Creatour and Father of all things in heaven and earth ; upon whom all animals and their births depend: and at whose beck or mandat, all things are created and begotten."* 3. Spontaneous generation of animals. — In this introductory view of the function of gene- ration, it may be proper shortly to inquire whether a regular affiliation from parent to offspring be an indispensable condition for the continuation of the species of every kind of animal, — a question somewhat speculative in its nature, but of considerable interest in rela- tion to some of the general doctrines of physio- logy, as well as closely connected with our present subject. It has already been stated in * Anatomical Exercitations concerning the Ge- neration of Living Creatures. London, 1653, p. 310 ct seq. general terms that origin by generation and the power of reproduction are characteristics be- longing to all organized bodies whether of the vegetable or animal kingdoms. The existence of life implies the sequence of decay and death, or m other words, those varied operations and changes which together constitute the living state continue to occur in each organized body for a limited period only : they sooner or later undergo a gradual alteration, are less regularly performed, and ultimately entirely cease in death. But although every individual belong- ing to the organized kingdom of nature is necessarily subject to death, the species of each plant and animal never becomes extinct, but is continued upon earth in an undeviating suc- cession of generations. The origin of.a mineral, on the other hand, is wholly independent of any pre-existing body of its own kind ; and, in the mineral kingdom, all those bodies are held to belong to the same species which agree in external form, physical properties, and chemical constitution. The mineral owes its first origin, as its subsequent increase, to the simple union of its component particles ; but the successive generations of every species of organized bodies constitute an uninterrupted chain extending from the time of their first creation, and in which the formation of every new link that is added depends on its tem- porary attachment to that which preceded it. So fixed, indeed, is the law of continued reproduction of organized bodies, that many naturalists have, in the absence of more definite distinctive characters, adopted the circumstance of reproduction as the only certain means of determining what individuals ought to be regarded as belonging to one species. While most naturalists readily admit the correctness of the above-mentioned general law, some are inclined to hold that it is not universally applicable, and that there are excep- tions to it both in the vegetable and animal kingdoms of organized nature. It is among the simplest kinds of plants and animals that these exceptions are conceived to exist, and more particularly among cryptogamic plants of the nature of mould, small microscopic animalcules formed in infusions of decaying organic matters, and the Entozoa which live in the bodies of other animals. These living productions are supposed by some to arise in- dependently of others of the same kind, nearly in the manner of minerals, by the aggregation of their component molecules, with this diffe- rence, that these molecules are of an organic kind. This sort of production without parents has been termed Spontaneous Generation. It has also received at different times various other appellations, such as equivocal, doubtful, primitive, original, and heterogeneous gene- ration. At one time it was a common belief among scientific men as well as the vulgar that many animals might be produced by sponta- neous generation, as for example, the numerous insects or their larvae infesting putrid sub- stances, various kinds of worms (Annelida), and Molluscous animals, as well as even 430 GENERATION. some fishes and reptiles ; but the increased knowledge of the structure and habits of these animals, and in particular the observations of Redi* and others, demonstrated the error of this opinion, and shewed it to have arisen merely from the circumstance of their real mode of generation not having been observed. After this many felt inclined to reject entirely the occurrence of spontaneous generation in any class of organized beings, and at the present day the question cannot be regarded as by any means entirely set at rest. From the nature of the observations and experiments required in an investigation of this nature, there is almost an impossibility of arriving at a perfectly satis- factory conclusion ; but so far as the facts at present entitle us to form an opinion, it may be stated that spontaneous generation, if it occurs, takes place in the simplest kinds of organized beings only ; that in most of them it is only occasional ; and that therefore this form of ge- neration is to be looked upon as a rare excep- tion to the usual and almost universal mode of reproduction by the separation of a living por- tion from a parent body. Minute animalcules, the greater number of which are so small as to be visible only with the microscope, are formed in the infusions of almost all kinds of organic matter, such as starch, sugar, gum, seeds, and different animal substances, when these infusions enter into pu- trefaction. The kinds of these animalcules are very numerous, and the circumstances which seem to determine the formation of one or other sort are infinitely varied. Thus the nature of the substance suspended in the infusion; and, in the same infusions, the degree of heat, the extent of the decomposition, the quantity and nature of the air admitted, the rapidity with which it is renewed, and the strength of the in- fusion or the relative proportion of water and organic matter in it, all appear to exert a certain inlluence in determining the formation of one or other of the kinds of animalcule. Two suppositions may be entertained regard- ing the first origin of Infusoria ; the one, that of their spontaneous generation ; the other, that of their developement or evolution from some pre-existing egg or germ. Those who disbe- lieve in the first and adopt the second hypo- thesis hold that the ova of the animalcules exist in the substances of the infusions, or are float- ing every where in the atmospheric air ; that these ova become developed in that species of infusion only which is suited to serve as their proper nidus or matrix; and that all the varieties of animalculse in different infusions depend upon the infusions being suited, from their composition or the external agencies to which they are subjected, to cause the develop- ment of different sorts of ova. The supporters of the hypothesis of Spontaneous Generation hold, on the other hand, that certain changes of composition of the organic molecules in the infusions, in whatever way induced, are the sole cause of the formation of one or other kind of ainrnalcule. * De Geaeratione Insectorum. Amst. 1686. Spallanzani,* one of the most strenuous op- ponents of the hypothesis of spontaneous gene- ration, shewed by very accurate experiments that no animalcules are formed when the access of air to the infusion is completely prevented, as for example, when it is covered with a little oil, or the vessel containing it is closely sealed ; and he thence concluded that the germs of the ani- malcules must exist in the atmosphere; but the supporters of the hypothesis consider them- selves as entitled to hold that no production of animalcules takes place in these circumstances, merely because the exclusion of the air has the effect of preventing that species of decomposi- tion which they regard as necessary for the formation of the Infusoria. It is stated by some experimenters that ani- malcules are produced when the infusions are exposed to hydrogen and nitrogen gases, or to atmospheric air artificially prepared ; in which it is held that there can be no living ova of animalcules. Again, it appears from numerous experiments, that when the infusions have been exposed to a boiling temperature, which is ge- nerally believed to have the effect of destroying the life of all organized productions, the quan- tity of animalcules formed is not diminished. Some air, it has already been stated, must always be present ; but so far as we are aware, the ex- periments on this point have not been per- formed in such a manner as to ascertain, whe- ther or not, when an infusion is allowed to come in contact with a considerable portion of con- fined air, and the whole apparatus is exposed to a temperature above that of boiling water, the production of Infusoria may still take place; and we are consequently obliged, in the absence of more direct experiment, to have recourse to analogical reasoning. The following considerations appear to us to throw the balance of evidence in favour of the spontaneous production of Infusoria, mould, and the like. Firstly, those organic matters which are most soluble in water, and at the same time most prone to decomposition, give rise to the greatest quantity of animalcules or cryptogamic plants. Secondly, the nature of the animalcule or vegetable production bears a constant relation to the state of the infusion, so that, in similar circumstances, the same are always produced without this being influenced by the atmo- sphere. There seems also to be a certain pro- gressive advance in the productive powers of the infusion, for at the first the animalcules are only of the smallest kinds or Monades, and after- wards they become gradually larger and more complicated in their structure; after a time the production ceases, although the materials are by no means exhausted. When the quantity of water is very small and the organic matter abundant, the production is usually of a vege- table nature; when there is much water,animal- cules are more frequently produced. Thirdly, on the supposition that infusory ani- malcules are developed from ova, it is neces- * Tracts on the Nature of Animals and Vegeta- bles. Edin. 1799, (transl.) GENERATION. 431 sary to conclude, from the experiments already referred to, that these ova are in some instances derived from the atmosphere, but yet the num- ber of Infusoria is by no means in direct pro- portion with the quantity of air. We are also reduced to the necessity of holding that every portion of the atmospheric air is equally im- pregnated with infusorial germs or ova, and that these bodies may remain for years dis- solved, as it were, or invisibly suspended in the atmosphere, and in a perfectly dry state — a supposition contrary to analogy, and not fully warranted by the fact that Vibriones may be resuscitated by means of moisture after they have been kept in a dry state for long periods. Fourthly, it may be remarked that the exist- ence of ova, as belonging to many of the Infu- soria, is entirely hypothetical, since most of these animals are known, when once formed, to propagate by other means, as by the division of their whole bodies or by budding. The production of infusorial animalcules from solutions of granite, silex, &c. recently described by Mr. Crosse, we have no hesitation in pronouncing to be either a mistake, or the result of changes occurring in admixed particles of organic matter. The Entozoa, or that class of animals which live only in the bodies of others, afford proofs of spontaneous generation still more convincing than those already mentioned. These remark- able animal productions are capable of existing no where but in the bodies of those animals which they naturally inhabit : they live either loose or attached, within cavities or imbedded in the substance of the textures; sometimes in places, such as the alimentary canal or respira- tory passages, to which the external air has access, and at other times in close cavities of the body, into which there is no opening from without, such as the chambers of the eye, the serous sacs, cysts, and other cavities, in the parenchyma of organs, the bloodvessels, &c. Entozoa do not live for any length of time after being discharged from the natural places of their abode ; and they survive a very short time only after the death of the animals in which they live. If Entozoa are not admitted to be the pro- duct of spontaneous generation, in order to ac- count for their origin, it becomes necessary to suppose either that these creatures themselves or their ova pass directly from one animal to another, or that they are introduced through the medium of air or water. Upon the first sup- position, carnivorous animals ought to be affected with entozoa, at least in greatest quan- tity, if not in some instances exclusively ; and the entozoa infesting any particular animal ought to be of the same kind as those which exist in the animal serving it for food. But such is by no means the case. Herbivorous as well as carnivorous animals have entozoa, and in no less quantity, and each animal is the abode of its own-peculiar kind. The same en- tozoa infest the same animals in all localities and climates; thus all the human entozoa, with the exception of the Dracunculus or Guinea- worm, which is an external parasite rather than a true entozoon, are the same in all races of men. Neither do we recognise any simi- larity between the entozoa infesting animals of a particular district and allied tribes of animals living in the neighbouring waters In adopting the second supposition that the eggs or germs of Entozoa may gain the bodies of animals by circuitous routes, we are met by many difficulties in addition to those already stated in reference to a similar explanation of the origin of Infusoria. Many Entozoa reside only in particular organs of the body, and in the very interior of these organs, as the human Cysticercus cellulosus in the choroid plexus of the brain, in the substance of the brain itself, in the chambers of the eye, &.c. so that it is necessary to suppose the ova of Entozoa to have been introduced into the circulation, carried through the smallest bloodvessels, and depo- sited in the places in which they are developed. Animals living in the same situations and feed- ing on the same substances have different kinds of Entozoa. The ova of some of the Entozoa, as for example, those of the common round worm, (Ascaris lumbricoides,) are so large that they could not pass through the largest even of the capillary bloodvessels : the ova are so heavy that they could not be transmitted through the atmosphere ; and the supposition of the passage of the ova from parent to offspring is opposed by the mechanical difficulty of the transmission, as well as by the facts that parent and child are not always affected with the same kinds of worms, and that though the complaint of worms may be said to run in families, yet many escape, and one or more generations in the hereditary succession are frequently exempt from it. En- tozoa have been observed in the foetus of ani- mals, and supposing them to be introduced from without, it would be necessary to hold that the entozoa themselves or their ova have passed directly from the mother to the child in the uterus, or to have traversed a route through which the globules of the blood are not trans- mitted. Some of the Entozoa, we may further remark, when once formed, are viviparous or bear their young alive; and with regard to these kinds it would be necessary to suppose that they may arise by invisible ova or germs as well as pro- pagate in the viviparous mode. These facts appear to us to speak strongly in favour of the occasional occurrence of sponta- neous generation, — " a doctrine which, had it not been applied in many instances where it was manifestly untrue, would have met with less ridicule and a more just appreciation than it has usually obtained." The epithet " spon- taneous," which we have retained as the most common, is equally inappropriate as applied to this or to any other of the processes of nature ; and the analogy of by far the greater number of plants and animals militates against the proba- bility of the hypothesis ; but it must at the same time be held in mind that the organized bodies in which spontaneous production has been said to occur differ widely in their general structure and functions from those which are reproduced by means of ova ; and we are 432 GENERATION. scarcely entitled to reject the hypothesis of their spontaneous generation, merely on the ground that, in this respect, they do not agree with the rest of the animal kingdom. Uarvey even, who established the proposition omne vivum ex ovo, seems yet to have acknowledged the ne- cessity of admitting some difference between the more ordinary form of generation by means of an egg and that which he called of the spon- taneous kind.* In conclusion, we may remark, that while we feel inclined to admit the existence of spon- taneous generation among some species of cryp- togamic plants, infusorial animalcules, and en- tozoa, it must be held in recollection that many of these productions, after their first origin, propagate their species as parents, — that the so- called spontaneous kind of generation is to be looked upon as no more than an exception to the general law of reproduction, — and that therefore extreme caution is necessary in admit- ting any organized body to be the product of spontaneous generation upon the mere negative evidence of the absence of its seeds or ova. II. SKETCH OF THE PRINCIPAL FORMS OF THE REPRODUC1IVE FUNCTION IN DIFFE- RENT ANIMALS. Before proceeding to detail the different steps of Human Generation, which forms the more immediate subject of consideration in this arti- cle, we shall endeavour to present a short pre- liminary sketch of the various forms which the reproductive function assumes in different classes of animals. Reproduction may be divided into non-sexual and sexual, according as the whole process is accomplished by one class of organs in a single individual, or by the concurrence of two diffe- rent kinds of organs placed either upon one or upon two separate individuals of the same species ; the first form occurring among the simplest kinds of animals only, the second be- longing to all the vertebrated and the higher classes of invertebrated animals. 1. Non-sexual reproduction. — Of the non- sexual mode of reproduction three principal kinds may be distinguished, viz. first, by divi- sion ; second, by attached buds; and third, by separated gemma. Fissiparous generation. — The most common form of the fissiparous generation, as the first of these varieties has been called, is met with in some of the simpler Infusoria; but it also occurs occasionally in animals higher in the scale. It consists essentially in the division of the parent animal body into a certain number of subordinate masses, each of which, being endowed with independent life, becomes a new individual similar to that of which it originally formed a part. In some of the Infusoria in which the process of subdivision has been mi- nutely observed, fissures are seen to form in the sides of the animal which is about to be repro- duced ; these fissures gradually enlarge, and meeting widi one another, completely separate * See his Exercitations, as before quoted, pp. 327 and 343. the parts. In one kind of fissiparous genera- tion the parent body is split into irregularly shaped masses, in some two in number, in dif- ferent others, four, six, eight, or twelve, and in one, the Gonium pectorale, into as many as six- teen. Each of the subordinate masses, when first separated from its fellow, has an irregular shape, from which it gradually passes into the form and size of its parent. In a second form of the fissiparous genera- tion, the infusorial animal is divided into two equal and symmetrical halves ; in some in- stances in a longitudinal direction, as in Bac- cillaria and some Vorticellte ; in others in a transverse direction, as in Paramcecium, Cycli- dium, and Trichoda. The propagation of the Volvox globator, a remarkable infusorial animalcule, may perhaps be considered as belonging to the first of the above-mentioned varieties of fissiparous genera- tion.* This animal consists of an external vesicle of a lenticular shape, moving rapidly through the water by means of cilia in a whirl- ing manner. Within this outer vesicle there are smaller ones of the same kind, in the inte- rior of each of which still smaller ones may be distinguished by the aid of a high magnifying lens. The outer vesicle may be regarded as the parent, and the inclosed vesicles as its young, for in propagation the outer vesicle bursts and is torn into shreds, while the inclosed ones are set free, each of them to execute its independent motions in the water, and in its turn to burst, and thus propagate its like in discharging those which it contains. A fissiparous kind of generation is not, how- ever, confined to the Infusoria, but occurs also in some of the Cestoidea and Annelida. The most remarkable example is met with in the Nais and Nerei?. In the first of these genera, a small portion separated from the tail becomes the new animal. Before the actual separation of this caudal portion, it is marked off from the rest by a notch, and there are gradually formed on its sides the joints, hairs, and other indica- tions of the organs of the complete animal in miniature. The notch enlarges, and the part at last drops off capable of independent existence. In the Nais, that part of the offspring by which it is attached to the parent becomes the head, and in this way, according to the singular notion of Gruithuisen, who observed this sort of reproduction with attention ,t the tail of a Nais may be considered as gifted with perpe- tual life, since this part is extended into each of the new descendants.! We may regard as somewhat analogous to this kind of propagation the multiplication of individuals by division, which happens occa- sionally only or from accident in several of the lower animals which are usually reproduced * Another view taken of the reproduction of the Volvox globator is, that the young are formed in the manner of internal buds. t Nov. Act. Nat. Curios, torn. xi. % The segments of the infusorial animalcule that is propagating in the fissiparous mode are united by the parts which afterwards become the tails of the new individuals. GENERATION. 433 in another manner. The most remarkable ex- amples of this are met with in Polypi, Entozoa, and Annelida. When the Hydra viridis is cut. through either longitudinally or transversely, each segment continues to live and grow, and is gradually furnished with those parts of the body of which it was deprived by the division. Thus, when the polype is divided across the body, the part with the head and tentacula is gradually furnished with a body, while ten- tacula grow on the elongated extremity of the other part. When, again, the animal has been divided in a longitudinal direction, and four tentacula are left on each part, the opposite edges of each segment turn round and unite so as to complete the tube of the stomach, and four additional tentacula are formed upon each. Segments of the Tape-worm, Filaria, and also of some other Entozoa, are capable of living after separation and being converted in- to independent animals. In the Leech and Earth-worm, as well as some other Annelida, the division of the body into two or more seg- ments is not invariably followed by death, but some or all of the portions continue alive, and, acquiring the deficient organs, become con- verted into more or less perfect animals. Gemmiparous generation. — The second form of non-sexual propagation that deserves our attention is that in which the new individual grows upon the parent as a bud or sprout, at first exhibiting little appearance of the form or structure of the perfect animal ; gradually as- suming its form while still attached to the parent stem ; and being afterwards separated to enjoy independent existence. The best known examples of this kind of generation occur in the polypine and coralline animals, and the process has been observed with great attention by Trembley in the Hydra viridis.* In this animal the young polype makes its first appearance as a small conical eminence on the body of the parent: this gra- dually enlarges and becomes cylindrical ; a cavity is formed in its interior, which at first is separate, but afterwards comes to communicate with the stomach of the parent, so that aliments taken by the parent penetrate into the stomach of the offspring. As the new polype enlarges, the internal cavity opens at the free extremity, where a mouth, provided wilh tentacula, is formed. The young animal then catches and swallows food for itself: this food at first finds its way into the stomach of the parent, but after some time all communication between the two stomachs is prevented by the closure of the root of the stem of the small polype ; and afterwards the offspring is detached from the parent, be- comes a separate individual, and in its turn propagates new ones from its sides. The time at which the separation takes place seems to depend in some measure on the quantity of food within the reach of the parent ; this occur- ring at an early period when the supply is small, and when there may be supposed to be a ne- * Mem. pour servir a l'Hist. dcs Polypes d'eau douce. Leyden, 1744. cessity for the young to move about from place to place in search of sustenance. Sometimes indeed the separation is much retarded, and the young ones also propagate while remaining on the parent stem ; so that the polype assumes a branched form, the parent stem bearing families of several generations. The Sertularia, Vorticella, Zoantha Ellisii, and Cornularia Cornucopias, also propagate by shoots somewhat in the same manner as the Hydra.* Reproduction by separated buds or sporules. — The last form of the non-sexual reproduction is that in which the young are formed from small detached masses after they are separated from the body of the parent. These bodies, generally of a rounded form, may be regarded as buds formed in the parent body, as those of polypes are, but detached from it before the evolution of the new animal begins. They bear the same relation to the offspring as the egg of higher animals to their foetus or embryo, and might be regarded as ova but for an important dif- ference of structure to which we shall after- wards advert. They are called spora?, germina granulosa, and gemma?, or germs : they are homogeneous in their structure, and the whole of the substance of which they are composed is converted in the process of their development into the new animal. In some animals these sporules are formed in all parts of the body indiscriminately, and are therefore found dispersed through it ; in others there is present a peculiar organ in which they are formed, constituting the simplest form of a reproductive organ. The Actinia, Me- dusa?, and some of the lower tribes of Mollusca belong to the first of these sets. In the A.phro- dita the sporules lie in the interstices between the different organs of the animal. In those animals in which a particular organ is provided for the formation of the sporules, the name of ovary is given to that organ, — an application of the term not strictly correct, as it belongs more properly to the organ in which complete ova are produced. The production of sporules from a particular generative organ is much the most frequent mode of their formation, and it ob- tains in the greater number of the lower tribes of Mollusca. It is a fact worthy of notice that the spo- rules of some Zoophytes, as those of the Sponge observed by Dr. Grant, are endowed with a faculty of moving, sometimes darting with ra- pidity in various directions through the fluids in which they are produced. These motions seem to depend on Cilia: the sporules are also provided with a hook, by which they become attached to other objects when they settle, * According to Burdach the propagation of the Volvox globator, already mentioned, and of the Vibrio, Cerearia, and Cysticeveus, is effected by the formation of buds, and differs from that of the polype merely in the buds being formed and dis- charged inwardly. We might, perhaps, consider the regeneration of lost parts which takes place in some animals higher in the scale than those pro- pagating by buds as a manifestation in them of a similar power. 434 GENERATION. preparatory to their growth and conversion into the fixed and immoveable Zoophyte. We may here recal to the recollection of the reader that the different forms of non-sexual reproduction which we have now attempted to sketch are not confined respectively to par- ticular classes of animals, for several of these animals are reproduced in more than one manner. The alleged instances of non-sexual propa- gation occurring in animals higher in the scale than those already mentioned are very doubt- ful, and ought to be regarded either as founded in imperfect knowledge of their reproductive organs, or as rare exceptions to the general law of their propagation by the sexual mode.* 2. Sexual reproduction. — The existence in animals of generative organs of two kinds, and the necessity of the co-operation of both these organs in reproduction constitute the distinc- tion of sex, or of male and female. In sexual reproduction both kinds of organs produce a substance essentially concerned in the process. The product of the female organ, or ovarium, as it is called, is the ovum or egg, a consistent organised body of a regular and determinate shape, in which the new animal is first formed and resides during its early growth. A whitish fluid is almost always the product of the male organ or testicle, — termed semen, or the semi- nal fluid, from a belief formerly prevailing that it constituted, like the seed, the greater part of the new being. Nature of the ovum. — The egg is naturally produced by the female without the concur- rence of the male, that is, the whole substance is apparently formed by the female organ, but * In many of those instances in which female animals have been supposed to give rise to produc- tive ova, the males have at first escaped notice from the smallness of their number or other causes ; and with regard to others of the lower animals, it may very reasonably be doubted whether the products called ova have not been rather of the nature of gemmae or sporules, such as those formed in the Actinia and other animals naturally propagating in the non-sexual manner. As in this predicament may be mentioned, according to Burdach, Oxyuris, Filaria, Ligula, Tricuspidaria, and others of the Entozoa ; Serpula, Sabella, and other Tubicola ; Cirrhopoda, and Mussels, and Scutibranchiata and Cyclobranchiata. The Syngnathus was erroneously regarded by Pallas, and the Perca Marina by Cavolini, as propagating without sex. It is, how- ever, probable that some animals provided with both sexual organs, and which usually propagate in the sexual mode, are occasionally reproduced without the immediate concurrence of the male. Thus the female Aphis, after being once impreg- nated by the male, bears, for a certain portion of the year, female young only, which are capable of being reproduced for nine generations without any of these female animals receiving any new influence from the male. In the last of tliese generations occurring in autumn, males also are produced which impregnate the females destined to carry on the same succession of generations during the next season. According to some this extension of the fecun- dating influence of the male through more than one generation is not confined to the animals just men- tioned ; but without doubt the instances in which this has been supposed to be the case have been greatly over-reckoned. the egg so formed is incapable of giving birth to a new animal unless it receive a certain por- tion of, or influence from, the seminal sub- stance of the male. This addition of seminal fluid to the egg makes no immediate percep- tible alteration in its structure or appearance, but awakens in it the power of reproduction, fructifies or fecundates it by causing a physical or vital change, the essential nature of which is not fully understood. In the egg immediately after its fecundation, none of the parts of the new animal are visible. A certain time must elapse during which the egg is exposed to certain favourable influences of heat, air, &c. before the com- mencement of those changes of development and growth in which the formative process of the new animal consists. The great mass of the substance composing the egg consists of a fluid, holding in suspension granules of animal, albuminous, and oily matter. The form of the egg is given by the external coverings, and there is in every egg a determinate part or re- gion, corresponding in all animals, at which the small rudimentary parts of the embryo first make their appearance. To this part of the egg, which might be called its germ, the power of independent life and reproduction appears more immediately to belong; the granular fluid serves but to afford nourishment to the young being for a certain period. A gemma or spo- rule, on the other hand, is generally held to differ from the ovum in being homogeneous in its structure, having no investing membranes, and being entirely converted into the substance of the new animal produced from it. In the present state of our knowledge, however, the distinction between an ovum and a sporule must be admitted to be somewhat arbitrary. The position of the male and female genera- tive organs upon the same or upon different individuals, and the place or manner of the development of the young animal from an egg, are the two most prominent circumstances in regard to which the forms of sexual reproduc- tion differ from one another in various animals. The principal processes in which sexual re- production essentially consists, are, 1st, the formation of an egg by the female organs ; 2nd, the secretion of the seminal fluid by the male organ ; and 3rd, the union of the sexes, and means by which the seminal fluid is ap- plied to the egg so as to confer fecundity upon it. Hermaphrodite generation. — In some of the lower tribes of animals belonging chiefly to the Annelida, Acephala, and Gasteropoda, the male and female sexual organs are placed on one individual, an arrangement of the sexual organs termed Hermaphrodite, and all the indi- viduals belonging to one species are consequently similarly formed In Insects, Crustacea, some of the Mollusca, and all the Vertebrata, the dif- ferent sexual organs are placed on two distinct individuals, which are thus constituted respec- tively male and female. In the greater number of those animals in which the last-mentioned arrangement exists, besides the sexual pecu- liarities, there are in each certain general differ- GENERATION. 435 ences in the structure of the other parts of the body. In Hermaphrodite animals there are two modes in which fecundation takes place. In some of the Acephala, and in the Holothuriae, the union of the sexual organs necessary for fecundation takes place in a single individual; while in others, as Helix and Lymneus among the Gasteropoda, copulation, or the union of two individuals, is required, and there is mutual impregnation, the female organ of each animal being fecundated by the male of the other, — a mode of impregnation which also exists in the common Earth-worm, Leech, and some other animals. Occasionally we find that three or more individuals engage in this sort of mu- tual fecundation, being arranged in a chain or circle.* (See Hermaphrodite.) Dioecious reproduction, or with distinct in- dividuals of different sexes. Oviparous and viviparous generation. — In those animals again in which the position of the sexual organs on separate individuals renders copulation neces- sary, the mode of production of the new animal from the egg seems to be the most prominent circumstance according to which the reproduc- tive process is modified. Thus, while in a certain number of them the young are born alive, in others they are hatched from eggs laid by the female parent. This constitutes the difference between Viviparous and Oviparous animals ; to the first of which classes Mam- malia belong, to the second Birds, and most Reptiles and Fishes. A short comparison of the more important steps of the generative process in the Mammiferous animal and the Bird will most readily explain the difference between viviparous and oviparous generation. -f * In the Cyclostoma viviparum the sexes are distinct. f Harvey in the Sixty-third Exercitation thus enforces the analogy between the oviparous and viviparous modes of reproduction. " I have already given you the reason why I have drawn out documents concerning all other egges from the egges of Hens ; namely, because they are cheap and every man's purchase." — " But there is more difficulty in the search into the gene- ration of viviparous animals ; for we are almost quite debarred of dissecting the humane uterus : and to make any inquiry concerning this matter in Horses, Oxen, Goats, and other Cattel, cannot be without a great deal of pains and expense Hut those who are desirous to make tryal whether we deliver the truth or not, may essay the business in Doggs, Conies, Cats, and the like." — " Hut we in the entrance of these our observations have con- cluded that all animals are in some sort produced out of an egg : For the foetus of viviparous creatures is produced after the same manner and order out of a pre-existent conception, as the chicken is formed and constituted out of an egge. There being one and the same species of generation in them all, and the exordium or first principle of them all is either called an egge, or at lest something answer- able and proportionable to it. For an Egge is an exposed conception from which a Chicken is pro- duced ; but a conception is an egge retained within, untill the foetus have attained its just bulk and magnitude : in other matters it squares with an egge," &c. *' Besides, as a Chicken is hatched out of an Egg, by the fostering heat of the sitting Hen, or some other ascititious hospitable patronage, so also the foetus is produced out of the conception in In both these classes of animals ova are formed from the ovary, and in both the ova are fecundated within the body of the female parent. The process by which the egg is sepa- rated from the place of its formation, and the changes it undergoes in being perfected after this separation, are the same in both : but after the fecundation and completion of the egg, it is differently placed in the two classes of animals ; for in birds the egg passes through the oviduct and leaves the body of the female parent, to be hatched into life under the influence of favour- able external agents ; while in the mammiferous quadruped, the egg remains within the uterus of the female generative organs, becomes at- tached to it, and has there formed from it the young animal, which does not quit the body of the parent until it is capable of independent life. The egg of the bird leaves the body of the mother provided with a considerable quan- tity of organic matter, by which alone, under the influence of heat and air, the embryo is nourished during incubation. The egg of the mammiferous animal is extremely small com- pared to the size of the young animal at birth, and the foetus consequently draws a continual supply of the materials of its nourishment from the uterus of the mother, with which it is more or less intimately connected. The residence of the child or young animal in the body of the mother during its formation and growth is termed pregnancy, or utero-gestation.* Ovo-vtviparous generation. — There are other animals, however, besides Mammalia, which bear their young alive, as is the case in many cartilaginous and a few osseous fishes, in several Batrachia, Sauria, and Ophidia, and also in some Gasteropodous Mollusca, Insects, Annelida, and Entozoa. But there is an im- portant difference to be pointed out between the viviparous form of generation occurring in these animals and that which belongs to the Mammalia. For the female generative organs of the above-mentioned animals, as well as the eggs they produce, resemble much more closely in their structure those of oviparous than those of strictly viviparous animals. As, in the animals now under consideration, the the egge, by the soft and most natural warmth of the parent. — " And then, concerning that which relates to procreation, the fcetus is produced out of the conception in the selfe same mariner and order as the chicken out of the Egg ; with this only dif- ference, that in an egge, whatever relates to the constitution and nutrition of the Chicken, is at once contained in it ; but the conception ( after the fcetus is now formed out of it) doth attract more nourishment out of his parent's womb ; whereupon the nourish- ment increases with the foetus." — " The first Con- ception, or Rudiment, therefore, of all Animals is in the uterus," (this applies to Quadrupeds,) " which, according to Aristotle, is like an egg co- vered over with a membrane when the shell is pilled off." And Harvey finally concludes wiih Aristotle : "All animals, whether they be swimming, walking, or flying animals ; and whether they be born in the form of an Animal or of an Egg j ; are all generated after the same manner." * The nature of the egg of viviparous animals, which has only recently been fully understood, will be described in a subsequent part of this paper, and more in detail in the article UVUM. 436 GENERATION. egg is proportionally large, the foetus grows principally by the assimilation of materials procured from it, and there is not that intimate connection of structure nor interchange of substance between the mother and foetus which occurs in Mammalia. The term ovo-viviparous is applied to the variety of reproduction now under consideration ; as expressing that in it, although the foetus is produced fully formed and alive, the ovum is merely hatched within the parent body. We find, accordingly, that this form of generation is liable to vary, and occasionally to run into the truly oviparous kind. Thus, some animals which bear live young at one season lay eggs at another season of the year, as occurs in some Insects ; and in others, as Lacerta agilis, the ova remain within the mother's body for a part only of the time employed in the development of the young; the process of hatching beginning and going on for a longer or shorter time within the female parent, and being completed as in the bird without. In all truly viviparous, in most ovo-vivi- parous, and also in many oviparous animals, the ova are fecundated within the parent's body ; and we find provided for the purpose of introducing the seminal fluid into the female genital organs, a more or less complicated ap- paratus in both male and female, by which the union of the sexes is brought about. In the greater number of strictly oviparous ani- mals, and particularly those that are aquatic, as osseous fishes and Batrachian Reptiles, fecundation is operated externally to the pa- rent body; that is, there is no union of the sexual organs of the male and female, but the ova laid by the female are covered with a certain quantity of seminal fluid shed by the male.* Utero-gestation in the Mammalia is termi- nated by parturition or the birth of the young; while in the bird or oviparous animal birth con- sists in the exclusion of the young from the egg. At this period in Mammalia, the organic con- nection between mother and offspring is dis- solved, and in both viviparous and oviparous animals the birth is accompanied by important structural changes, which fit the offspring for independent life and aerial or aquatic respira- tion. The young of Mammalia after birth, though they cease to be organically connected with the mother, continue to derive a certain quantity of support from her, feeding on the milk secreted by the mamma?. But in all other classes of animals, the young are at birth capable of feeding on external aliment. Varieties in respect to utero-gestution and the developement of the young. — There is con- siderable variety among different animals in the degree of perfection at which the young have arrived at the period of birth. Thus, Insects, Batrachian Reptiles, and some other * In the land Salamander.which is ovo-viviparous and breeds in the water although there is no sexual union of the male and female, there is yet internal fecundation, the seminal fluid being carried into the oviduct of the female along with the water in which it is effused. animals leave the egg at a very early period ; differing widely from their parents in struc- ture and functions, they live for a time in a masked or larva condition, and undergo after- wards various changes or so-called metamor- phoses before attaining the mature condition. Fishes leave the egg while their structure is yet very incomplete; and even in the higher animals we observe varieties in this respect: thus, some birds, more especially those build- ing on trees, are unfledged, blind, and help- less when the shell is broken; and some quadrupeds, among which may be mentioned the Rodentia, Feline, and Canine species, are at birth blind and weak, and with little power of supporting their natural high tem- perature.* The most remarkable instance of variety of the kind now alluded to, how- ever, occurs in the Kangaroo and other Mar- supial animals, the generation of which de- serves more particular mention in this place as it exhibits a considerable deviation from the more ordinary reproductive process in Mam- malia, and is attended with some important modifications in the structure of the generative organs. In the Mammalia generally, it has already been stated that there is an intimate organic connection between the foetus and mother, by means of which the former is supplied with the materials of its growth. The intimacy of this union (as we shall explain more fully else- where) varies much in different tribes of ani- mals. It is greatest in the placenta of the human female, and from this there may be traced a series of animals in which it becomes more and more loose. According to recent researches in Comparative Anatomy, there is also observable in the descending series of these animals a nearer and nearer approach in the general structure of the body, and in the conformation of the generative organs to the oviparous type. This approach to the ovipa- rous structure is most strongly marked in the Marsupiata, as the Opossum, Kangaroo, &.C. and in the Monotremata, as the Ornithorynchus and Echidna. + Marsupiate generation. — The foetus of the marsupiate animal leaves the uterine system of the mother or is born at an early period of its formation, while it is yet of a very small size, and its organs are comparatively imperfectly formed. On being born it is introduced by the mother into the pouch or marsupium formed by a reduplication of the integuments of the lower part of the belly, and a short time after it gets there, the foetus is found attached by its mouth to one of the nipples of the mamma?, which are concealed within the mar- supium. The young of the marsupiate animal * Under the head of OVUM we shall shew that all animals undergo changes which constitute me- tamorphoses of one kind or other during their for- mation or development. t See the interesting papers by Mr. Owen on the Generation of the Kangaroo and Ornithoryn- chus in the Philosophical Transactions, part ii. for 1834, p. 333, and in the Transactions of the Zoological Society, vol. i. p. 221. GENERATION. 437 there receives its food by the mouth and is nourished by digestion at an early period of its advancement; and, although its external form and organization very much resemble that of the foetus of other mammiferous animals at a similar stage of their advancement when they are still confined to the uterus of the mother, their internal organization undergoes at the time of their exclusion the same remarkable changes which occur at birth, and which are connected with aerial respiration and the independence of the vital functions.* Monotrematous generation. — The generation of the Ornithorynchus and other monotrema- tous animals deserves also to be noticed here as differing in some respects from that of other Mammalia; but, unfortunately, this subject, which has been involved in obscurity ever since the first discovery of these remarkable animals, notwithstanding that several important facts have been recently ascertained, cannot be con- sidered as completely understood. The Orni- thorynchus and Echidna were long regarded as holding an intermediate place in respect to their organization between Mammalia and Birds. The existence of mammary glands was denied by the first dissectors of these animals ; and from this circumstance principally, toge- ther with the analogy in general structure al- ready alluded to, the Ornithorynchus was be- lieved by many to be oviparous. The recent investigations of Owen have proved the ex- istence of mammary glands as well as the suckling of the young, while they at the same time shew that the generative organs and the ova within the ovaries partake in a great degree of the oviparous structured In this approach to the oviparous type, however, it has been satisfactorily shewn that the Ornithorynchus resembles the class of Reptiles rather than that of Birds. The ova of this animal have not, how- ever, been found in any of its haunts ; and, although no one has yet had an opportunity of dissecting the gravid uterus, naturalists are now inclined to hold the opinion that it bears its young alive. Should this be fully proved to be the case, the Ornithorynchus may with justice be considered as an example among mammiferous animals of the ovo-viviparous form of generation, most analogous to that occurring in the Slow-worm or Adder; the ovum being, at the time of its descent into the oviduct, of proportionally large size, and there being no proper placenta or intimate organic union between the mother and foetus. Comparison of animal and vegetable repro- * For the details respecting the structure and functions of the generative organs of the Marsu- piata, the mode of passage of the embryo from the uterus to the pouch, see the article upon the Com- parative Anatomy of these animals, M ARSUPIATA. It is curious to note that until the discovery of the uterus of these animals by Tyson, the vaguest conjectures prevailed respecting their mode of reproduction, it being even supposed by some that the foetus grew from the first attached to the nipple, and consequently originated as a bud. t The name of Monotremata applied to these animals, it may be remarked, means with (me vent, they having a cloaca. duction. — In concluding this rapid sketch, it may not be out of place to introduce here a few remarks upon the analogies existing be- tween animal and vegetable reproduction. The seed of plants is generally regarded as corresponding to the egg of animals. The seed and egg correspond in being both the residence of the germ or living part from which the new organized body springs, and also in both containing a certain quantity of matter destined for the temporary nourishment of the growing embryo ; but the germ is in a different state in the seed and egg ; for while in the egg none of the parts of the new being are visible at the time of its separation from the parent, the rudiments of the embryo are fre- quently to be found, small but simulating in some degree the plant, in the germ of the seed when it is perfected, and before the commencement of germination. The circumstances favourable to evolution give rise to the development of the embryo in both, but in the animal the influence of the male conferring fecundity on the egg makes no perceptible alteration in the germ, while in the plant no part of the seed, neither cotyledon nor germ, is formed unless fecundation by the pollen of the male takes place ; and the seed is not separated from the ovary or place of its production until the rudimentary parts of the embryo are already sketched out. We have examples of non-sexual repro- duction of plants among the Cryptogamia, in which the new plant springs from sporules or granules endowed with the independent vital properties of the seed. The greater number of monocotyledonous and dicotyledonous plants may be regarded as hermaphrodite, as both the seeds and pollen are formed on the same individual, while in others the position of the sexual organs on distinct individuals corresponds with the more common arrangement in the animal king- dom.* In different tribes of plants we also observe examples of occasional propagation in a man- ner different from the more common one by seeds or sporules. Thus the buds and branches, which are the means of their ordinary growth and increase, may,when removed, be capable of independent existence and give rise to distinct plants, or even when still on the parent stock may take root and grow anew. Some buds separate naturally and are evolved in the man- ner of seeds when placed in favourable circum- stances ; and in a third class of instances sepa- rated buds are preserved in the collections of nutrient matter constituting the tuberous and bulbous roots by which many plants are pro- pagated. To complete the enumeration of the points of analogy between animal and vegetable re- production, it may be stated that there is the same reason for believing in the spontaneous generation of some of the Cryptogamic plants as in that of Infusorial animals. * As in strictly Hermaphrodite, Monoecious, and Dioecious plants. 438 GENERATION. The following table is intended to exhibit a synoptical view of the various forms of the Fissiparous Gemmiparous . . Hermaphrodite. Dioecious III. REPRODUCTIVE FUNCTION IN MAN AND THE HIGHER. ANIMALS. 1. Sketch of this Junction in man. — In now proceeding to a more detailed account of the function of generation, our description must be confined to the process of reproduction in the human species and in those animals which are most nearly allied to man. The following may be mentioned as the principal steps of the reproductive process in the female of the human species. The human offspring is derived from an egg like that of all the more perfect animals. The egg is gradually formed in the Graafian vesicle of the ovary at the period of maturity. In productive sexual union the vagina and uterus receive a certain quantity of the male seminal fluid, and a series of changes are induced in the female generative system which have the effect of dislodging one or more ova from their residence in the ovary, and of bringing these ova into contact with the seminal fluid, in order that they may be fecundated or rendered fruitful. The mechanism of the discharge of the ova is the following. The Graafian vesicle swells, and bursts at its most prominent part. The ovum escaping from its interior is received by the fimbriated cavity at the commencement of the Fallopian tube, along which tube it gradually passes until it reaches the interior of the uterus, where it arrives probably in ten or twelve days after sexual union. There is every reason to believe that before the ovum reaches the uterus it has already been exposed in some part of the genital organs to the influence of the male semen, and that it is consequently fecundated. We shall have occasion after- wards to inquire more minutely into the place and manner of this fecundation. The female is now said to have conceived or to be impreg- nated, and the ovum to be fecundated. We shall endeavour, for the sake of clearness, to bring the history of the steps of this process reproductive process occurring in different classes of animals. Parent splits, each part a new animal. 1. Transverse. 2. Longitudinal. 3. Irregular. Parent splits and discharges the young. Budding upon the parent stock. Separated buds. Gemmae or sporules. 1. On all parts of the body. 2. On one part or organ only. Both sexual organs on one individual. 1. Self-impregnation. 2. Mutual impregnation. Oviparous, laying eggs which are hatched. 1. External fecundation. 2. Internal fecundation. Ovo-viviparous. Eggs hatched within the maternal body. Mammiferous, suckling the young. 1 . Monotrematous. 2. Marsupial. 3. Placental or strictly vivi- parous. under the three distinct heads of, first, the changes of conception as regards the female, secondly, the process of fecundation as relating to the male, and thirdly, the effects of the union of the male and female product. Before the ovum reaches the uterus a change has already commenced in the interior of that organ, which in its farther progress has for its object to bring about an organic union between the uterus and the foetus with its coverings. The minute embryo soon becomes visible in the ovum, has envelopes formed over it which become connected with the lining membrane of the uterus, and as it advances in growth continually receives a supply of nourishment from the bloodvessels of the uterus. It is nourished in this way during the whole of its intra-uterine life, at the termination of which the child is brought into the world or born, being expelled from the uterus by those pain- ful efforts and contractions of the uterus con- stituting parturition or labour. The child is row capable of being nourished by digestion of food in the stomach, independently of any organic connexion with the mother, and breathes air by its lungs. Although all or- ganic connexion, however, between the mother and child is now dissolved, yet the infant is for a time dependent on the mother for nou- rishment, receiving by sucking from the mam- ma- the milk, which it assimilates by its own independent powers. In the present article our object is to describe only the processes of conception and fecundation, referring to the article Ovum for an account of the growth of the foetus, and to the articles Uterus, Ovary, &c. for the more minute anatomical and functional relations of these organs in the unimpregnated and impregnated states. Organs of reproduction. — The organs of reproduction in both sexes are frequently divi- ded by anatomists into external and internal, according as they are situated more or less near GENERATION. 439 the surface of the body ; but a more suitable arrangement of these organs in a functional point of view is that which is founded on the part which each of them is destined to perform in the generative act. The male organs consist •of the penis and urethra, testicles, seminal vesi- cles, seminal ducts, prostatic body, and Cowper's glands: the female organs, of the vulva, clitoris and nymphas, vagina, uterus, Fallopian tubes, and ovaries. The testicles in the male and the ovaries in the female are the productive organs, secreting or forming by an organic process the product of each respective sex ; the vasa defe- rentia and vesiculae seminales conduct and retain for a time the seminal fluid ; the Fallo- pian tubes conduct downwards the ovum from the ovary to the uterus ; the uterus receives and retains the ovum during pregnancy or the formation of the child. These constitute the internal organs ; the remaining parts are the external organs, and are chiefly connected with sexual union or the expulsion of the products from the body. The glans penis, the clitoris, and the neighbouring parts are the seat of that feeling which accompanies the venereal act: the penis, with its urethra, serves to conduct the seminal fluid into the vagina and uterus of the female : the vagina, besides receiving the seminal fluid, is the issue for the child when it is expelled from the uterus in parturition. Puberty .—It is only during a stated period of life that animals are capable of reproduction. In infancy, youth, and old age the functions of the sexual organs are in abeyance. The name of puberty is given to that period of life at which either sex first becomes capable of re- production, at which time various important structural and functional changes occur both in the sexual organs and in the whole eco- nomy. These changes are upon the whole more marked in the female than in the male, a cir- cumstance which may be attributed to the longer and more intimate connexion of the female with the product ; the maternal parent affording a supply of nourishment to the child during the whole of its intra-uterine life, while the male does no more than furnish momenta- rily a small quantity of the seminal fluid necessary for fecundation. Structural differences of the sexes. — In in- fancy and youth the two sexes do not differ materially in the general shape of the body, nor in physical powers ; but as the age of puberty approaches, and the sexual organs undergo those changes which fit them for the performance of their appropriate functions, the male and female bodies become altered in form, and acquire a more marked difference, while the mental and physical powers also par- take of this discrepancy. We shall do no more than mention here the most striking of these peculiarities, as a more detailed account of them belongs to another place. Besides these differences which belong im- mediately to the sexual conformation, the com- paratively broader shoulders and wider chest of the male, and the larger pelvis and ab- domen of the female, are universally known as constituting the chief peculiarities in the general contour of the body. The smaller size of the whole body in the female, amounting in general to a tenth of the whole height, the greater slenderness of the female frame, the less prominence of the muscles, the more tapering and rounded shape of the limbs, the greater quantity of fat under the skin and elsewhere, the smaller, smoother, and finer bones, and the more delicate texture of some other parts of the body, are all peculiarities of female conformation contrasting with the opposite qualities in the male body. As belonging to the male may be mentioned the low and rough voice from the larger size of the larynx and longer vocal cords,* the occurrence of hair on the chin, upper lip, and cheeks, as well as over the body and limbs, in which situations it is rarely met with in the female, the greater physical power and activity, capa- bility of enduring fatigue and daring, &c. As these changes in either sex are gradually developed, hair grows on the skin covering the symphysis pubis, in the neighbourhood of the genital organs,f and later under the axillae. The local changes attendant upon puberty in the male are the enlargement of the penis, its more frequent erection, and accompaniment of this by the sexual feeling ; the enlargement of the testicles, vesicute seminales, prostatic gland, and other accessory parts; the more depending condition of the testicles in the scrotum ; the secretion of a certain quantity of the seminal and prostatic fluids ; and, after the attainment of the full sexual powers, the occasional spontaneous emission of some of the seminal fluid, occurring in general at night during sleep, and being accompanied by some sexual feeling in dreams. In the female at this period, both external and internal organs undergo a considerable and rapid enlargement ; the mons veneris and external labia become more full ; the clitoris and nymphffi in many, but not in all, become susceptible of a certain degree of swelling or erection ; the breasts enlarge, the vesicles in the ovaries become dilated, and some of them more prominent, and there is established a periodical discharge of a certain quantity of a sanguineous fluid from the internal genital organs. Menstruation. — This periodical loss of blood demands the attention of the physiologist as one of the most remarkable of the sexual pecu- liarities of the human female, and as bearing an intimate relation not only to the generative process, but to most of the other functions of the economy. The periodical recurrence of the discharge of blood every lunar month or twenty-eight days * Comparative measurements have been made of the length of the vocal cords in boys imme- diately before and alter puberty, and those of the young men have been found to be nearly double the length of those of the boy. f Hence the name of this bone and of the period of life of which we are now speaking — pubes and puberty. 440 GENERATION. has given to it the name of menses or men- struation : the Greek word catamenia is also employed to denote it by medical men, and the English expressions of " the illness" or " the courses" are those in most common use among the vulgar. The menstrual flow of blood lasts usually for about five days, beginning and leaving off gradually, and being in greatest quantity towards the middle of the period. The in- terval is thus generally about twenty-three days. The discharge in general takes place slowly, or drop by drop. The menstrual flow of blood is preceded in most women by some symptoms of fever, a quicker and fuller pulse than usual, languor, headach, pains in the back, and frequently in the hypogastria or region of the ovaries, and by many other symptoms of general derange- ment of the functions, particularly in weak or unhealthy women. In young women upon the occasion of the first appearance of the menses all these symptoms are frequently more strongly marked. Menstruation may be regarded as the most certain sign of the arrival of puberty, and of the fitness of the human female for marriage, as there are very few instances on record in which conception has taken place before the occurrence of the menstrual discharge. It continues for the whole of that period of life during which women are capable of bearing children ; and after this, when it ceases, a considerable change in the female constitution ensues : the " change of life " or " critical period" is said to have arrived, from the liabi- lity there then is to the conversion of the plethoric state, previously relieved by men- struation, into some morbid affection either of the sexual or other organs of the body. During menstruation, the uterus, vagina, ovaries, and other parts of the genital organs are usually more vascular and turgid with blood than in the interval ; the mammae, which exhibit at all times a remarkable sympathy with the condition of the uterus, frequently participate in this increased activity at the menstrual period, as they then swell and be- come hard. Menstruation consists essentially in the exudation of a fluid resembling blood from the female genital organs, and principally from the uterus. Haller states that the blood has actually been observed to proceed from the uterus in women labouring under prolapsus of that organ, and John Hunter as well as others have found the cavity of the uterus filled with the fluid in women who have died during menstruation. Menstruation usually ceases during pregnancy, and in the majority of women during lactation also. In those instances in which the monthly flow has continued to take place during preg- nancy, there is reason to believe, according to Haller, that it may have proceeded from the upper part of the vagina, as the first changes attendant upon utero-gestation usually close firmly the neck of the uterus. The quantity of fluid which exudes during one menstrual period amounts in general to five or six ounces ; but this is subject to great variation from the mode of life of the indivi- dual, state of her health, diet, and other circumstances. The quantity is usually greatest, ceeteris paribus, in healthy women living well, but the increase of the quantity above a certain point or its diminution below another are equally to be regarded as unnatural or diseased states of the action. In tropical countries the quantity is greater than in more temperate regions, amounting occasionally to twelve or even twenty ounces. In Lapland and some other northern countries the quantity is, on the other hand, much below the mean, being occasionally as low as three ounces ; and yet in both these situations the women are to be regarded as within the bounds of health. The quantity of fluid lost in menstruation is increased by all those circumstances which cause a determination of blood to the pelvis or its contained viscera; hence the effect of posture, irritating diuretics, drastic purgatives, and those medicines termed emmenagogues. The nature of the fluid discharged in men- struation has not yet, we believe, been investi- gated with sufficient accuracy. It bears a close resemblance to blood, having generally the colour of the venous kind. It is generally fluid, but sometimes coagulates from exposure to air: it is generally believed to contain less fibrine than blood, and to be less prone to putrefaction. Respecting the causes of the menstrual dis- charge and its uses in the economy, many very absurd hypotheses have been advanced in me- dical writing's. It was a common belief among the ancients that the menstrual fluid exerted a baneful influence on every living object, plant, or animal, and many of the institutions and laws of antiquity shew that this natural process was looked upon with abhorrence. The corres- pondence in the length of time of the moon's changes with the recurrence of the menstrual period induced many to believe in an influence exerted by the moon on the female generative system ; but the error of such a notion is suffi- ciently proved by the circumstances, first, that more women are not found to menstruate at one period of the moon's changes than at another., and, second, that the women of any place men- truate at all different times. Besides this, many women do not menstruate regularly every lunar month. In some this change takes place every three weeks, in others every fortnight, and there are many in whom there is a varia- tion of one or two days on either side of the common period of twenty-eight days. When we consider the circumstances pre- viously mentioned respecting the intimate con- nexion subsisting between the menstrual flow and the processes of reproduction, we shall be led rather to the opinion that menstruation is to be regarded as a means of relieving the female system periodically from an overplus of blood which exists during the whole of the time in which it is capable of propagation. It occurs at this period of life only, it generally ceases during pregnancy, and it may therefore GENERATION. 441 correctly be regarded as the indication of the presence in the system of that quantity of nutrient matter, which, during pregnancy, is destined to serve for the nourishment of the child. We say that this flow does no more than indicate the surplus quantity of blood in the female genital organs ; for, as Burdach remarks, the loss of six ounces of blood for ten successive lunar periods amounts to only three pounds twelve ounces, whereas the foetus and its appendages during that period attain the weight of from ten to fifteen pounds, to which we might add the enormously increased weight of the uterus in order to estimate the whole addition which is made to the uterine system during pregnancy. Again, during lac- tation or nursing the tendency to a super- abundance of blood or plethora in the uterus is generally relieved by the flow of milk from the mammae, which, as has already been remarked, sympathize very constantly with the uterus and other parts of the generative system. Such a tendency to plethora as that we have just alluded to, it is scarcely necessary to remark, can have no connexion with lunar or planetary influences, and we are, perhaps, more justified in classing it along with those other changes of the economy which indicate a remarkable ten- dency in the human constitution to periodical recurrence of its actions. The crises of fevers on days terminating periods which are most frequently of the dura- tion of seven, fourteen, twenty-one, or twenty- eight days, are of this kind ; and it is deserving of notice that menstruation recurs more fre- quently in periods, the number of days of which are multiplies of seven, than in any others.* It has been attempted to be shewn that the male is subject to a periodical plethora in some respects similar to that which gives rise to menstruation in the female, but without any just reason, unless we choose to consider as such the gradual accumulation of seminal fluid, which frequently takes place in healthy men of sanguine temperament, and which gives rise to its periodical emission. With regard to menstruation we shall only farther remark that, according to Ilaller, Bur- dach, and some others, women are more liable to become pregnant immediately or within a few days after the cessation of menstruation than at other parts of the interval ; the probable reason of which will appear from details given in a subsequent part of this article. Periodical heat in animals. — None of the lower animals in the natural state appear to be subject to anything like a menstrual change or periodical discharge of blood. In lascivious Apes and in some of the domestic animals fed * According to the researches of Mr, Roberton of Manchester, detailed in an interesting paper, pub- lished in the Edinburgh Med. and Suig. Journal, vol. xxxviii. p. 237, out of 100 women, in sixty-eight the menstrual discharge returned every fourth week ; in twenty-eight every third week ; in one every se- cond week ; in ten at irregular intervals. These varieties usually exist as family and constitutional peculiarities. VOL. 11. highly, an exudation of bloody mucus from the vagina and external genital organs of the females sometimes occurs, but this is manifestly quite different from menstruation. There is, however, in most of the lower animals a very obvious periodicity in the functions of the reproductive organs; for while the human female is, during a certain period of life, nearly equally fit for propagation at all times, this is the case with very few animals, and, indeed, chiefly among those living in the un- natural state of domesticity. At certain seasons of the year there occurs in most of the lower animals a determination of blood to the genital organs of the female, accompanied by sexual desire, which leads them to the propagation of their species. This state of excitement, generally named " the heat,"* lasts for a longer or shorter period ; in the ewe for twenty-four hours only, in the cow and mare for a few days, in the bitch nine or ten days, and in the hen-pheasant for as long as two months. In most animals, after it has run its accustomed course, it disappears naturally, but it is more certainly and sooner dispelled by fruitful sexual union. The heat belongs more properly to the female than to the male, as there are many species whose females receive the male only at par- ticular seasons, while the male is at all times fit for propagation. In others, constituting the majority of instances, the male organs are sub- ject to the same periodical increase of activity as the female. The male in these animals is usually in heat at an earlier period than the female.f In some animals there is a more frequent periodical return of the heat than in others; thus the ewe which remains unimpregnated conies in heat every fourteen days ; the cow and some apes, the mare, ass, and buffalo every four weeks; the sow every fifteen or eighteen days ; but in these animals the high feeding attendant on domesticity may very probably occasion a more frequent and less natural return of the period of heat than would occur in the wild state. It would appear that the season of the year at which animals most commonly breed is subject to very many and extensive variations, according to the temperature, latitude, and other circumstances connected with the country which they inhabit. During the continuance of the heat a peculiar odour is exhaled from the genital organs, and there exudes chiefly from the external organs some bloody mucus, which, in some lascivious apes, resembles blood so much as to have given rise to the belief already alluded to that these animals menstruate. Age at which puberty occurs. — The appear- * Termed the Itut in the deer, wild boar, tkc. t In some male animals the signs of heat are very apparent. The fine colour of the plumage of most male birds in the breeding season, the deep colour of the comb, &c. in gallinaceous fowls, the thickness and bushy hair of the deer's neck, the greatly enlarged size of the testicles in the cock- sparrow, may be mentioned as familial' examples. 2 G 442 GENERATION. ance of puberty is gradual in both sexes, but, upon the whole, more slow in the male than in the female. The age at which it takes place varies in the same and in different countries according to the mode of life, physical and moral education, and other circumstances. It takes place at an earlier age in woman than in man : in the former most frequently in this country at from the age of thirteen to sixteen years, in the latter from fifteen to eighteen years; but instances are not unfrequent of girls menstruating and of boys passing into manhood one or two or even more years sooner or later than the above-mentioned periods, as from ten or eleven to twenty or twenty-two years.* These variations are to be considered as dependent on constitution in the greater num- ber of instances; but in respect to their ocbasional causes, it may be stated that all those circumstances which produce a determi- nation of blood to the sexual organs or pelvic viscera, which relax the body generally, or turn the attention of the young to the sexual function, tend to bring on sooner than natural the local changes of puberty. Warm rooms, a sedentary mode of life, particular kinds of reading, and some bad habits are all hurtful in this respect. According to the observations of many tra- vellers, puberty arrives sooner in warm than in temperate climates ; and some have hence too hastily concluded that the warmth of the tropical country has been the cause of the more precocious appearance of menstruation in wo- men and puberty in men, an opinion the error of which is shev\n by the fact that instances of very early puberty are not unfrequently met •with in high northern latitudes. f The occur- * According to Mr. Roberton's observations pre- viously quoted, the following are the ages at which 450 women began to menstruate : In their 1 1th year 10 „ 12th 19 „ 13th 53 „ 14th 85 „ 15th >> 97 „ 16th 76 „ 17th >* 57 „ 18th 26 ,, 19th 23 „ 20th 4 This table shews that the age of puberty of females in this country extends over a considerable number of years, ind is more equally distributed than is commonly alleged. t The opinion that menstruation happens at an earlier age in warmer climates is very generally enter- tained, as may be seen by a reference to the works of Haller, Boerhaave, Deninan, Burns, Dewees, and others. Mr. Roberton has successfully shewn its inaccuracy by an appeal to the facts stated by modern travellers, as llearne, Franklin, Richard- son, and Back with regard to the Northern Cana- dian Indians ; by Lyon and Parry with respect to the Esquimaux ; by Clarke in reference to the Laplanders; and by Tonke in relation to the Northern Russians ; all of whi. The following table exhibits approximatively the sizes of the spermatic animalculae of some * Beytrage zu der Lehre von der Spermatozoen, Wien, 1833. 2 II 2 460 GENERATION, of the more common animals in parts of a line:*— Parts of a line. Helix pomatia -410 Lymneas stagnalis -300 Aquatic Salamander -200 Viper -050 Polecat x Guinea-pig 1 Mouse V -040 Linnet 1 Sparrow J Hedgehog I Anguis fragilis S Bull -028 a^::::::::::::::::::::::1-^ Goat ~\ ^::::::::::::::::::::\-::\^ Rabbit ) Common fowl -016 Frog -013 D°g ] -008 Man (according to Der Gleichen) S Man (according to BufTon) -006 Gruithuisen states that he has observed the seminal animalcules to propagate by division of their bodies, or fissiparous generation. But we are far from attaching implicit faith to all that has been stated even as matter of observa- tion regarding these bodies. We ought not to omit in this place to state another and a different view which has recently been taken of the nature of the moving particles of the semen ; we mean that of G. Treviranus, who, founding chiefly upon observations made by himself in the lower animals, as Mollusca and Insects, adopted the opinion that these particles are not independent animals, but ana- logous in their structure and properties to the fibrils and particles occurring in the pollen of plants. Their motion he seems to regard as of the same kind with that discovered by R. Brown to exist in infusions of these and oilier minute floating particles, and not as of an animal or spontaneous kind. He deduces this conclu- sion principally from the alleged observation that the motion of the so-called animalcules is not the same as that of ordinary Infusoria, but differs from it in this respect, that it is simply vibratory and constant, and not interrupted by any of those stops or pauses and changes from place to place which are held to indicate spon- taneity in the motions of Infusoria.f Some of the facts already stated by us shew the fallacy of the opinion of Treviranus. Baer, who regards the Spermatozoa as distinct living animals, holds that Treviranus has observed only an imperfect condition of the animalcule, and states in the work of BurdachJ. some addi- tional observations of his own made in the snail, which promise, when pursued further, to remove some of the difficulties respecting the nature of these bodies. Baer states that he has observed the head and tail parts to become separated from one another, and both these parts, but especially the tail, to move about after separation. Baer has observed also that there are various stages of formation and change of the seminal animalcule, during which not only their form but also their motions undergo remarkable alterations, and he supposes that Treviranus must have observed the spermatic animalcule of the snail and mussel in one of these stages only. Observations made* by the author of this article and by Dr. Sharpey in the frog, seem to bear upon this point, and to be in some degree confirmatory of the view given by Baer. We have almost invariably found, in observing the seminal fluid of the frog in the spring or summer, that the animal- cules contained in it are not of the kind de- scribed by authors in this animal, viz. with both head and tail, but of the thread-like form only. These were collected in bundles in the thick part of the fluid, and generally moved with a continued vibration such as we have previously described. In the thin part of the fl nid there were a few round-shaped or monad- like infusoria. Occasionally it happened that when water was added to the thick part of the fluid, and the bundles of the thread-like bodies were artificially broken down, some of them moved progressively through the fluid by the undulatory riggling of one of the extremi- ties ; and during their motion we were surprised to see some of those, which, when at rest, ap- peared to be destitute of any cephalic part, fre- quently assume the appearance of a head. This phenomenon we remarked to be owing to the circumstance that the end by which the animal- cule moved forward was bent backwards on the middle of the body, so as at one time to give exactly the tadpole-like appearance which is represented as a head in their plates by Messrs. Prevost and Dumas. There could be no doubt that this was the case, for in some, in which at one time the end was so closely joined to the body that it could not be seen, at another it loosened from it, and the thread-like animal- cule still continued to progress in the fluid with its curve forwards, and the two ends (of unequal length) floating separate and loose. The author has observed nearly the same phe- nomena in the spermatic fluid of the pigeon. Lastly, the observations of R. Wagner on the spermatic fluid of the Guinea-pig seem to prove more decidedly than any of the previously men- tioned facts that the spermatic infusoria are subject to remarkable changes of form at dif- ferent periods, and that they even go through a regular gradation of development. The discrepancy of these observations makes * This table is taken principally from the mea- surements of Prevost and Dumas given in their excellent account of the seminal animalcules pub- lished in the .Annales des Sciences Naturelles. t See a paper in Tiedemann's Zeitschrift, vol. v. part 2, 1835. f Vol. i. second edition. * These observations were made five years before the publication of this article. For further infor- mation respecting the Spermatozoa we refer the reader to the articles Entozoa and Semen ; in the last of which Mr. Wagner, who has investigated their nature with great success, will fully explain his views. GENERATION. 461 it apparent that we ought in the present state of our knowledge to be very cautious in making any general conclusion regarding the nature of the spermatic animalcules. It appears to be fully proved that some such animalcules always exist in the seminal fluid of animals when they are fit for propagation ; but it is by no means certain that they belong exclusively to the fluids which are the product of secretion in the tes- ticle, for animalcule very similar to them in general appearance and in motions are to be found in various other fluids and organs of animals. In all those parts of the body in which mucous secretions are accumulated, ani- malcule are formed, and in some of the lower animals the Cercarie of intestinal mucus are hardly to be distinguished from the animal- cule of their seminal fluid. Nor is it well ascertained that these animal- cules belong exclusively to the fluid of the tes- ticle, and do not sometimes occur in the secre- tions of other parts of the generative organs. They exist no doubt frequently in the seminal fluid of the testicle, but some recent observa- tions seem to shew that they are frequently imperfect in the fluid of that organ, and that in some animals at least they are not fully formed and do not acquire their powers of active mo- tion till some time after the seminal fluid is secreted, and when it has passed from the tes- ticle into other parts of the generative organs. On this account some hold, and with good reason, that they are to be regarded as the pro- duct of reciprocal changes of the ingredients of the seminal fluid on one another, rather than as secreted along with that fluid directly from the bloodvessels of the testicle, as others have sup- posed. In conclusion, we would remark that in regard to the seminal animalcule having both the body and tail, such as those that may be seen in the dog, cat, rabbit, or other quadru- peds, and which were described by the dis- coverers and early observers of the seminal animalcule, no one who has had an oppor- tunity of observing them carefully with a good lens magnifying three or four hundred diame- ters can doubt for a moment that they bear a close resemblance to some of the Infusoria, and that both from their structure and motions they are with as much justice as the Infusoria to be regarded as distinct animal beings. With re- gard to the other kinds above mentioned, or the changes they may undergo in different stages of their existence, farther investigations appear necessary to enable us to form an opinion. Although the spermatic animalcules, like other Entozoa, are formed only in living ani- mals and may be regarded as dependent for life on those animals in which they occur, yet they retain their life for a time after they leave the body. Thus the spermatic animalcules of the Polecat, which Prevost and Dumas ob- served with much attention, continued to move for fifteen or twenty minutes on the object- stand of the microscope ; and these experimen- ters state that when the seminal fluid is allowed to remain in the genital organs, the animalcules continue to live for fifteen or eighteen hours after the death of the animal. Their motions cease instantly when a strong electric spark is passed through the fluid containing them. Immediately after the discovery of the semi- nal animalcules, they were made the subject of very fanciful hypotheses, and were conceived to throw quite a new light upon some of the ob- scure parts of the generative process. To the supporters of the theory of pre-existing germs, their discovery opened up the prospect of being able to trace backwards one link more than had previously been done in the chain of life which connects the parent and offspring. By some they were considered as the cause of sexual en- joyment or venereal propensities. By others, the animalcule were held to be of different sexes, and, according as one or other gained the egg during fecundation, to give rise to a male or female offspring, and thus to determine its sex. They have been supposed by others to form the first rudiments of the foetus or lay the foundation in the germ of the egg from which the offspring is afterwards developed, and fecundation has thus been resolved into the simple passage of a seminal animalcule into the germinal part of the egg; and finally, one or two of the most fanciful of such dream- ing physiologists have (as we had occasion to remark at a former part of our article) not failed to perceive on a sufficiently minute inspection of the animalcule, that it already possessed all the organs belonging to the mature con- dition of the animal in the seminal fluid of which it existed ; compressed no doubt into a very small space, but from which it was easy to suppose the offspring to be formed by evo- lution.* Such notions require no refutation. Let us rather pass now to the inquiry of how far ob- servation and experiment have tended to throw light upon the essential circumstances upon which the fecundating property of the seminal fluid depends. The nature of the change which confers upon the egg the power of production is entirely unknown to us, and we already remarked towards the commencement of this article that this action is to be ranked among those vital operations of the animal economy which are placed beyond the reach of our means of investigation. We should with equal prospect of success proceed to inquire how life originates and is maintained in the parent, as to investigate the secret man- ner of the transmission of the vital spark from the parent to the offspring. The physiologist who would study this subject must therefore limit his inquiries in this as in other departments of his science to the search after those condi- tions or chain of circumstances which appear to be essential to the occurrence of the parti- cular change or phenomenon which is the object of his investigation. Our present object, then, is not to investigate the nature of the change by which the living * Gaultler, Generation dei Hommes et dea Animaux. Paris, 1750. 462 GENERATION. productive power is given to the egg, but to endeavour to establish what are the essential conditions of fecundation. Difference between the fecundated and unfe- cunduted ovum.- — In the first place, in reference to this subject, it would be interesting to know whether any material difference exists between the structure of the fecundated and unfecun- dated egg. In the common fowl we have seen that the whole substance of the egg, the yolk and ger- minal portion, the albumen, shell, and mem- brane, may be formed in the ovaries and oviduct, and excreted from the body of the hen without any connection with the cock ; but such an egg, though apparently the same in structure with that which is laid after connection with the cock, when subjected to the requisite heat, undergoes none of the changes of development which incubation induces in the fecundated egg, but only passes into chemical decomposi- tion like any other dead animal substance. Did any difference of structure exist between the fecundated and unfecundated egg, we should be disposed to look for it first in that part of the egg which is more immediately con- nected with the new being, viz. in its germinal portion ; but we regret to say that the investiga- tions of naturalists have not as yet pointed out any marked difference in a satisfactory manner. Malpighi, it is true, long ago pointed out a difference in the structure of the cicatricula of the egg of the common fowl which had had connection with the cock, and those of the hen living single, and the observations of this author were afterwards confirmed by Prevost and Dumas. In the impregnated egg the cicatri- cula is a well-defined whitish spot, with a re- gularly formed transparent area in its centre ; while in the unimpregnated egg there is no re- gularly shaped transparent area, but rather a number of small irregular clear spaces scattered over the surface of the cicatricula. We fear, however, that this appearance of irregularity exists as well in some eggs that have been laid after connection with the cock, and that the shape or appearance of the cicatricula can scarcely be depended upon as informing us whether an egg has been fecundated or not, since that appearance is much influenced by the state of the nucleus or white matter of the yolk situated below it, as well as by the state of the cicatricula itself. This subject is worthy, however, of the most accurate investigation, as it appears to offer the prospect of affording some information on this very obscure part of the generative process. In the ovarian ovulum, the vesicle of Pur- kinje, it will be recollected, occupies the centre of the cicatricula ; and this vesicle exists in the ovulum so long as it remains within the ovarian capsule, whether the hen have connection with the cock or not. In the impregnated fowl the germinal vesicle of Purkinje bursts, and leaves the transparent area in the centre of the cicatri- cula at the time when the ovulum passes from the ovarian capsule into the oviduct ; but it re- mains to be known if the same is the case, or what phenomena ensue upon the escape of the ovulum from the ovarium in the fowl which is entirely separated from the cock.* We do not know with certainty what befalls the vesicle of Purkinje in the ovulum of Mam- malia at the time of its escape from the ovarium. The analogy of all oviparous animals is strongly in favour of the supposition that it bursts in the same manner. M. Coste states that it does not burst, and Valentin supports an opposite view. While, therefore, we feel disposed to adopt the opinion that the seminal fluid, in fecunda- ting the egg, operates its peculiar change chiefly on the germinal part, and that the bursting of the germinal vesicle is very probably connected with the change of fecundation, it must be ad- mitted that further observations are still want- ing to afford a satisfactory proof of the correct- ness of these hypotheses. Is material contact of the semen and ovum necessary for fecundation ? — No one has ever discovered any of the seminal fluid within the egg : the most minute observation does not de- tect any appearance of this. A question then naturally presents itself in reference to the sub- ject of our present inquiry, viz. whether it is necessary that a certain quantity of the sub- stance of the seminal fluid should be brought into actual contact with the egg in order to cause its fecundation ? and if so, in what man- ner and in what part of the female organs such contact is brought about? Were we to look no further than to the manner in which fecundation is effected in many of the inferior animals, we might be in- duced at once to form the opinion that the mere contact of a certain quantity of the seminal fluid with their ova, in whatever way brought about, is all that is necessary for producing their fecun- dation. Thus, in the greater number of fishes the milt or seminal fluid of the male is shed over the spawn of the female after it is laid in water, without there being any nearer sexual intercourse; the fecundation is external to the body of the female, and we thus know with certainty that the ova and the seminal fluid are the only parts immediately concerned in the process. The same is the case in the common frog, in which there is copulation ; for in that animal, although the male and female remain united firmly together during a longer period than any other kind of animal, yet this union is not a means of producing fecundation, but rather of promoting the discharge of unim- pregnated ova from the generative system of the female. There is in fact no true sexual union : the spawn is laid by the female un- fecundated, and the male (separating then in general from the female) sprinkles seminal fluid on the ova floating in water. External and artificial fecundation. — The mode of fecundation just now mentioned sug- * We have long had the intention of instituting a series of observations comparing the changes of the impregnated and unimpregnated ovum in the oviduct, but have not yet had an opportunity, and we recommend it to those who may be anxious to engage in the investigation of this subject. GENERATION. 463 gested to Spallanzani* the ingenious expe- riment of artificial fecundation, which he first performed, and which furnished the most con- vincing proof that could be obtained, that, in such animals as the frog, sexual union is not essential to fecundation, and that, when the ova are ripe and the seminal fluid of the suit- able quality, the mere contact of the male and female products is sufficient to confer fertility upon the ova. Spallanzani opened very many female frogs at the time of propagation, but before they had laid any spawn, and consequently before im- pregnation could have occurred, and he satis- fied himself that the ripest ova extracted from the oviduct, and placed in water, gradually passed into putrefaction without undergoing any of the changes of development; while some of the same ova, upon which he had sprinkled some of the seminal fluid taken from the body of the male, and placed in similar vessels of water, had tadpoles formed from them in the same manner exactly as those which were fe- cundated by the male frog itself, f The same experiments were performed by Spallanzani on toads and newts with exactly the same result. . Spallanzani, in order to avoid every fallacy, allowed the female to remain in union with the male, and to lay her spawn in the natural way, preventing only the access of any of the seminal fluid of the male to the ova, by tying up the hinder part of the male's body in oiled silk, and these ova were alike barren, unless he added to them some of the seminal fluid in the artificial mode. TreviranusJ mentions the performance of the experiment of artificial fecundation in Fishes, viz. on the spawn of the Salmon, Trout, and Carp, by Duhamel and by Jacobi. Jacobi's experiments were repeated by Dr. Walker of Edinburgh ; and very recently it has again been performed on the spawn of the Tench and Bleak by Itusconi of Pavia. (Cyprinus Tine a and Alburnus.) The very complete series of experiments of Messrs. Prevost and Dumas§ on the frog- afford the most satisfactory confirmation of those of the Abbe Spallanzani. The following appear to be the more im- portant results deducible from these two sets of experiments. 1st. That a very small quantity indeed of the seminal matter is requisite for the fecundation of the ovum. 2d. That dilution of the seminal fluid with water within certain limits does not impede, but rather is favourable to its operation. 3d. That the absorbent power of the albumi- nous or gelatinous matter which surrounds the black yolk is highly useful in bringing the seminal substance in contact with the yolk, where it is obvious its effect must be produced. * Dissertazioni di fisica animale, &c. t This experiment the author has more than once performed with a similar result. t Erscheinungen und Gesezte des Organischen Ijebens. § Annul, des Sciences Nat. torn. i. This albuminous covering, corresponding to the white of the bird's egg, possesses the remark- able property of absorbing water, somewhat like gum tragacanth, in a determinate quantity, and thus increases greatly in bulk after being laid in water. In the experiments referred to, the absorption of the water by the jelly was fully demonstrated by the immersion of the ova in coloured water, and it was found also that the experiment of artificial fecundation suc- ceeded best when the ova had not been im- mersed in water for any considerable time pre- vious to the addition of the seminal fluid. The fecundation was less certain the longer the ova were allowed to remain in water before the ad- dition of the semen ; and it was shewn that this did not depend simply on the length of time of the separation of the ova from the body of the parent, by the fact that ova taken from the oviduct and kept without moisture re- tained their susceptibility of being fecundated for a much longer period, as sixteen or twenty hours. 4th. That the seminal fluid of the frog retains its fecundating power for about thirty hours after it has left the body of the male. 5th. Attempts were made by both the expe- rimenters above quoted to ascertain, by way of experiment, whether the seminal animalcules are indispensable to fecundation. Spallanzani came to the conclusion that the seminal fluid did not lose its peculiar powers although de- prived of its animalcules, or although the ani- malcules were dead ; but it must be admitted that the means employed by that observer to ascertain the presence or absence of the seminal animalcule were inferior to those we possess in more recent times. Messrs. Prevost and Dumas, who, it has already been remarked, consider the animalcules as the most important part of the seminal fluid in reference to its fecundating properties, state that they found in their experiments, that that part of the seminal fluid which had been subjected to a very careful filtration, and which had thus been wholly de- prived of its animalcules, had lost all fecunda- ting power, while the substance which remained in the filter, and which was rich in animalcules when diluted with water, possessed the same powers of fecundation as the pure seminal fluid. We think this experiment requires repetition and some modifications, for other ingredients, besides the animalcules of the seminal fluid, might be retained on the filter. 6th. Both Spallanzani and Prevostand Dumas have attempted to estimate the quantity of seminal fluid required for the fecundation of a certain number of ova, and the latter observers, pursuing their favourite idea to the utmost, have even endeavoured to calculate the number of animalcules which are necessary for the fructi- fication of one or more ova. In Spallanzani's experiments two grains of the semen of the toad fecundated one hundred and thirteen ova. Five grains of semen were mixed with eighteen ounces of water; the point of a needle dipped in this was made to touch an egg for an instant and produced fecundation. The proportion here might be estimated as 464 GENERATION. semen 1, to egg 1,064,000,000. The addition of a larger quantity of semen, or its remaining longer in contact with the egg, did not, accord- ing to Spallanzani, render the fecundation more complete than the instantaneous contact of the wetted needle's point. Prevost and Dumas state that they found the number of ova fecun- dated by a given quantity of seminal fluid is always below that of the animalcules which they estimated that fluid to contain; and by a sim- ple process of calculation it was easy to find how many animalcule served each ovum. A certain quantity of seminal fluid, for example, containing 225 animalcules, served to fecun- date 61 only out of 380 ova, to which it was added, so that each ovum required about 3| animalculce for its fecundation, or making allowance for a few of the animalcule which went astray into other ova, it may be stated as three in round numbers. It will be long before the vital processes can be traced with the arith- metical precision displayed in this calculation. Unfortunately for the calculations and even the observations upon which they are founded, one of the authors at a subsequent period published the theory which appears to have prompted them to revive an old and fanciful notion that the animalcule forms the rudiment of the new being. The animalcule, according to this hy- pothesis, makes its way through the stiff jelly surrounding the yolk, gains the centre of the germinal membrane, and esconces itself there in the very centre of that germinal membrane, laying thus the foundation of the primitive streak or the brain and spinal marrow of the foetus : its position (which is always the same) being no doubt determined by the laws of po- larity depending upon the electro-magnetic properties with which, according to equally fanciful theorists, the rudiments of the new being in the egg are endowed. Hitherto cold-blooded and oviparous animals only have been alluded to; but there are not wanting facts which render it highly probable that in viviparous animals also, contact of se- minal fluid with the ovum is the essential part of the fecundating process. Thus, Spallanzani confined a bitch for fourteen days before the arrival of heat, and for twenty-six days after it, so that, during that time, it could have had no connexion with any dog, and at the time of the heat he injected by means of a syringe a quantity of the dog's seminal fluid into the vagina. The bitch brought forth three young exactly at the usual length of time from the period of heat; — an experiment on artificial fecundation, which may in some sort be said to have been performed in the human species is the well-known instance in which John Hun- ter recommended to a man affected with hy- pospadiac malformation of the urethra, which rendered intromission of the seminal fluid impossible, the injection, by means of a sy- ringe, of the seminal fluid into the vagina, — an operation which, it is related, was attended with complete success. While these facts on the one hand tend to shew that no parts of the genital organs and no other agents are concerned in fecundation excepting the seminal fluid and the ova, and on the other hand afford the only positive evidence that can be obtained, that actual con- tact of the one with the other is necessary to induce the change, they have appeared unsa- tisfactory to some physiologisls,who cling to the opinion that, in quadrupeds and birds at least, contact is not necessary, and that fecundation may be effected either by some hidden sym- pathy (or concurrent action taking place in remote parts) between the external and internal organs of the female, or that this change may be operated by some imponderable influence which emanates from the seminal substance, to which the vague name of aura seminalis has been given. Course of the seminal fluid within the female organs. — In pursuing our examination of the alleged evidence upon which these and similar hypotheses are founded, it will be necessary to consider in this place another question, respecting which it is difficult in the present state of the inquiry to form a decided opinion, viz. whether, on the supposition of the seminal fluid and ova coming into actual contact, the course of the seminal fluid within the female organs of generation can in any instances be traced, and in what part of these organs it may be supposed to meet with the ova and operate their fecundation. In the first place the examples of ovarian conceptions, or rather gestations, have been ad- duced by some as a proof that fecundation necessarily takes place in the ovaries them- selves. But from what was said in a former part of this paper, it will be seen that such a belief is founded on an erroneous view of the nature of these misplaced gestations, as well as of the phenomena which occur in the ovary after conception. There is no reason to believe, we may repeat, that ova found developed in the neighbourhood of the ovary have retained their situation within the Graafian vesicle. On the contrary, they must in all probability have been first discharged from the ovary upon the rupture of the vesicle, and their places occu- pied by corpora lutea; and they may have been fecundated either while loose in the cavity of the peritoneum, or when they have descended some way in the Fallopian tubes, and meeting with the seminal fluid in the course of that tube, have been returned to the vicinity of the ovary by some inverted or un- natural action of the parts.* Although, therefore, no very decided opinion respecting the place at which fecundation occurs can be formed from the observation of what are termed ovarian and tubular gesta- tions, we are inclined to think that they shew * We need do no more than mention here a view taken by Sir Everard Home of the uses of the corpora lutea, which he holds to be a means of bringing the seminal fluid into contact with the ovum of the Graafian vesicle. This opinion re- quires no remark, as it will be at once perceived that it proceeds on the assumption, shewn to be erroneous in a former part of this paper, that the corpora lutea are formed before the rupture of the vesicles. GENERATION. 465 that this process may take place, in some in- stances at least, in the upper parts of the Fal- lopian tube, or even in the infundibulum. In the second place physiologists have en- deavoured to argue respecting the place of fecundation from the well-known fact that, in the common fowl, turkey, and probably some other birds, a single connexion with the male serves to fecundate more than one ovum, as, for example, in the common fowl twelve or twenty ova; and that, as there is usually only one ovum in the progress of descent through the oviduct at one time, we must conclude either that the yolks or ovula are fecundated by the rise of the seminal fluid to the ovary, or that the seminal fluid remains somewhere in the course of the oviduct, to be applied to the ovum as it descends. If we exclude the notions of an aura and sympathetic action, the former of the above-mentioned views ap- pears to us the most consistent with the facts that have already come under our knowledge. The notion entertained by Fabricius and others that there is a receptacle for containing the seminal fluid in the oviduct appears to be in- correct; and we find it difficult to believe that the seminal fluid can remain dispersed through the oviduct, or confined in any particular part of it and retain its power of fecundation, when we consider the manner in which each yolk descends from the ovary and receives in its passage the various accessory parts constituting the albumen and external coverings. Of course, in supposing fecundation to take place in the ovary, there remain two suppositions which may be entertained regarding the mode in which the seminal fluid gains the ovula ; for it might either pass directly up the tube of the oviduct, or be absorbed and take some cir- cuitous course. In the third place, we are inclined to think that in quadrupeds the ova must be already fecundated before their arrival in the uterus, that is, either in the neighbourhood of the ovary or in the tubes, for this reason, that at the time when the ovum first arrives in the uterus, it has already become considerably enlarged, and has undergone some of the changes of development ;* and when we con- sider how very regular and progressive these changes have been observed to be from the time when the ovum first enters the tubes, we shall be disposed to conclude that fecundation very probably takes place before then, or in the upper part of the tubes. In the fourth place, attempts have been made to trace the seminal fluid in animals opened shortly after sexual union. Most authors agree that much of the seminal fluid * We do not mean here to state that the parts of the foetus have appeared, but only that changes in the germinal membrane preparatory to the forma- tion of the foetus have taken place. Nothing of this kind lias ever been found in the unimpregn.ited animal, no appearance of any ovum, whicli, con- sidering how often vesicles are burst without sexual union, we think must have been the case had the ovum undergone the same changes in the unim- pregnated as in the impregnated animal until its arrival in the uterus. frequently flows out of the vagina soon after coition, and Harvey, De Graaf, and Haller were all unable to discover any traces of seminal fluid in the uterus even of various animals killed and opened soon after sexual union. Haller, however, while he states this as the result of his experiments, admits that the means which he possessed of ascertaining the presence or absence of the semen were im- perfect, and he himself believed that fluid to have entered the uterus. Various other physiologists, also, state that they have found seminal fluid in different parts of the female organs. Morgagni and Ruysch had two opportunities of examining the body of the human female very soon after coition, and found, on opening the uterus, a fluid which they regarded as semen. John Hunter states that he observed the same in a bitch, as also did Hausmann. But in all these instances some doubt may be enter- tained regarding the fluid which was considered as semen. Prevost and Dumas, trusting to the occur- rence of the seminal animalculae as a certain sign of the presence of seminal fluid, state that they have observed these animalcules, at different periods after coition, both in the uteius and tubes of dogs and rabbits; and it appears to result from the careful series of experiments performed by these physiologists that the longer the time was which had elapsed after coition, the farther the seminal fluid had advanced upwards within the female genital passages. Thus, at twenty-four hours after coition a great quantity of animalcules were found in the cornua of the uterus, but none either in the vagina or farther up the tubes; at forty-eight hours nearly the same was the case : on the third and fourth days there were many animalculse still in the cornua and some in the tubes, which continued in the dog till the fifth and sixth days; and upon one occa- sion only they observed a few animalcules near the infundibulum. Burdach and others, again, are not inclined to place much reliance on these observations, because animalcule of the nature of Cercariae have been noticed in the genital passages of female animals which had had no connection with the male. In the fifth place, experiments on the me- chanical obstruction of the uterus, Fallopian tubes, and vagina, appear of considerable im- portance in reference to this part of our sub- ject. Experiments of this kind were per- formed first by Haighton,* and afterwards by Blundel^ the results of which, making allow- ance for the more accurate knowledge we now possess respecting the indications afforded by the condition of the vesicles and corpora lutea in the ovary, may be stated as follows : — 1st. That when one of the cornua of the uterus or Fallopian tube of the rabbit is divided within a few hours after coition, and oblite- ration of the tube has followed, although corpora lutea are formed in both the ovaries * Philos. Transact, vol. Ixxxvi. p. 173. 466 GENERATION. (as a consequence of the rupture of vesicles), ova are not to be found on the injured side of the uterus, but pregnancy takes place on the other side. 2d. When the vagina was divided in a like manner at its upper part, although the usual number of corpora lutea were found in the ovaries, pregnancy did not occur. That the mere wound itself locally, or its hurtful effects on the constitution, did not prevent the develop- ment of the ova, was proved by the experiment purposely made of dividing the parts in the same way and allowing them to reunite by adhesion without obstruction of the tube, in which case uterine pregnancy occurred nearly as in the natural condition. 3d. In another set of experiments oblite- ration of the tubes was caused to take place at a later period, probably when the ova had descended and may be supposed to have met with the seminal fluid, and in these animals pregnancy occasionally but not always oc- curred. It would appear to follow from these expe- riments, that the seminal fluid does not rise in the female genital passages immediately upon its introduction, and not for more than a day after coition, and that those circumstances which impede the rise of the seminal fluid prevent fecundation. But they do not warrant the conclusion that impregnation must occur in the ovaries, since the vesicles may have burst, their contents be discharged, and corpora lutea formed without the seminal fluid having had access to the ovary; a fact which is well shewn by the interesting experiment performed by Dr. Blundell, of producing an obliteration of the upper part of the vagina in the unim- pregnated rabbit, then allowing coition to take place, and then finding, no pregnancy, but corpora lutea in the burst vesicles of the ovary. These experiments appear also as of im- portance in shewing that neither absorption of the semen by the lymphatics or bloodvessels, nor the passage by any other circuitous route, nor indeed any sympathetic action established by sexual union between remote parts of the female generative organs, can be the means of producing fecundation. There are, no doubt, great difficulties in the way of our understanding by what manner the seminal fluid accomplishes the passage up- wards in the genital organs of the female. Thus, the small size of the Fallopian tubes at once strikes us as a powerful obstacle ; but in many animals, as, for example, in the Rumi- nantia, there is an equally great difficulty in comprehending how the seminal fluid gains the uterus itself even; for in these animals the os uteri forms a long and uneven passage, inter- rupted by many hard cartilaginous projections, and closed in general by a very viscid and tena- cious mucus. But yet the seminal fluid must in all probability enter the cavity of the uterus.* * Burdach mentions, as supporting the view that the seminal fluid may be absorbed by the blood- vessels or lymphatics, and being carried into the In conclusion, we would remark that we must either suppose fecundation to be the effect of the actual contact of the seminal fluid with the ova in the upper part of the Fallopian tube or somewhere near the ovary, or we are reduced to form the opinion that the action of the seminal fluid on the lower part of the female genital organs may be twofold, viz. first, causing the commencement of the process of fecundation by a sympathetic in- fluence on the upper part of the tubes, and, in the second place, perfecting the change in the uterus when it meets there with the ovum. We feel inclined, in the present state of our knowledge, to give a preference to the first of these opinions. Nature of ike fecundating process. Hypo- thesis of an aura, fyc. — We return now to the consideration of the essential nature of the change of fecundation. The opinion that fecundation is attributable to the agency of an aura or emanation from, and not to the material contact of the seminal fluid, is founded chiefly upon alleged instances of conception having occurred in individuals (of the human species) in whom, from unnatural formation or disease, no direct passage existed from the vagina or external aperture to the internal organs, as well as upon some of the circumstances above alluded to, as shewing the difficulty of such a passage both in man and animals, even in the natural condition. No very definite idea, it may be remarked, can be attached to the term " aura," for it has been employed in varous acceptations by diffe- rent authors ; one considering it as of the nature of a gaseous or vaporific exhalation from the seminal fluid, another denying it the nature of a substance even of the most etherial kind, and considering it more as a spiritual or vital principle; and a third regarding it as of the nature of a nervous impression. These discrepancies only shew us that the term aura is to be taken rather as an expression for the unknown agency of the seminal fluid which causes fecundation, than as indicating its modus operandi or the part of its substance more immediately concerned in the action. Some authors have, however, even referred to direct experiment in favour of the agency of an aura. Mondat, for example, (De la Sterilite, 4to. edition, p. 17) states that he witnessed experi- ments performed by Morsaqui, of Turin, with this view, from which it was found that the bitch could be impregnated when it was im- possible, as he states, that the substance of the seminal fluid could in substance pass into the uterus or other parts. Recurved tubes, con- taining in the closed end a quantity of the dog's seminal fluid, were introduced into the general circulation occasion fecundation when it arrives at the ovary or other parts of the internal organs, Casp. Bartholin, Perrault, Sturm, and Grassmeyer. Dr. Harlan of Philadelphia, in a volume of Experimental Essays recently published, states that he found that the injection of semen into the bloodvessels of a bitch put a stop to the heat sooner than would otherwise have been the case. GENERATION. 467 vagina of the bitch in such a way that none of the fluid itself could escape, but only an emanation, vapour, or supposed aura rising from it, and in eighteen out of thirty animals on which the experiment was 'performed, with the subsequent occurrence of impregnation. But until these experiments shall have been confirmed by careful and frequent repetition, we must be allowed to doubt the possibility of performing such an experiment in a sufficiently accurate manner. Spallanzani, with a view to investigate the powers of a vapour supposed to rise from the seminal fluid, exposed a quantity of the ripe unimpregnated spawn of the frog for some time in the same vessel with a quantity of seminal fluid, the latter being placed at the bottom of the vessel, the ova at the top, and never was any fecundation produced; — an experiment, it is true, from which no more than negative evidence can be derived, but upon the whole more worthy of trust as being subject to fewer fallacies than those of Mondat. The instances in which it has been alleged that impregnation has taken place in the human female without there being any possibility of the seminal fluid itself passing inwards in the female genital passages, are of a very doubtful nature, and liable to so many sources of fallacy, that we feel little disposed to admit them as grounds of proof of the agency of an aura seminalis. In some of the cases in which it has been found, either in the course of pregnancy or at the time of child-birth, that the female passages are obstructed, there is reason to be- lieve that the closure has been produced sub- sequent to the occurrence of conception ; and the same may be said of those cases of ovarian gestations in which an obliteration of the Fal- lopian tubes has been observed. In the greater number of such cases, it may also be observed, the malformation of the parts has consisted in the much contracted state of the external orifice or some other part of the passage, rather than in their absolute closure, so that there was merely a difficulty and not an impossibility of the entrance of seminal fluid. But in opposi- tion to such vague and ill-ascertained observa- tions, a variety of circumstances, which it is not necessary to particularize, might be adduced, tending to show how very easily in the human female as well as in other animals all mecha- nical obstructions to the entrance of the seminal fluid into the uterus tend to prevent conception. General conclusions respecting fecundation. In conclusion we would remark, 1st, that while we readily admit a very small quantity indeed of the seminal fluid to be sufficient to produce fecundation, we think that what has previously been stated warrants the conclusion, that material contact of a certain quantity, however small, of the seminal fluid with the ovum is necessary to give rise to its fecunda- tion, and, consequently, that the hypothesis of an aura is untenable. And for the same reasons it follows that there are no just grounds for holding the opinion either that fecundation consists in a sympathetic action of a nervous kind, or that it is brought about by the absorp- tion of the semen into the circulatory or lymphatic vessels of the generative system. 2d. It is sufficiently obvious that in quadru- peds there is no exact proportion between the quantity of seminal substance or fluid received by the female or emitted by the male, and its effect in producing fecundation, — a circum- stance which points out a distinction which ought always to be borne in mind between that vital change on the female genital system and the whole economy and ovum, and the simple physical re-action which may take place be- tween the semen and ovum themselves. 3d. We may regard venereal excitement of the genital organs and impregnation of an ovum as different phenomena, for though they usually occur together, there are instances in which they take place quite independently. 4th. The action of impregnation is to be regarded as sui generis, or quite peculiar among the vital processes. It is not capable of being imitated by any other substance than the seminal fluid, and neither experiment nor ob- servation enables us to form the most distant conjecture what the nature of that action may be, which, from the influence of the male pro- duct, confers upon the ovum a new and independent life, and enables to give birth to a new individual the mass of organic matter in the egg, which, without the change of fecun- dation, would prove altogether barren and undergo no other changes than those of similar dead matters. The action, however, is in some respects reciprocal, and we cannot determine what part either of the two agents concerned performs in the change of fecundation : we know only this, that unless the seminal fluid be of the suitable composition it is ineffectual, and that ova are susceptible of its influence only when in that period of their evolution when they are ripe. Nor can we with certainty fix on what part of the egg the influence of the male semen more immediately operates. Since the foetus grows from the centre of the germinal layer, it has been commonly supposed that this is the part of the egg which is most imme- diately affected by fecundation, but we know nothing of this; and it might be held, on the other hand, that the effect of fecundation ope- rates on the rest of the contents of the egg in enabling them to be assimilated round the germinal centre or rallying point of the de- velopment of the new being. 5th. It has not yet been shewn that one part of the seminal fluid is more necessary to impregnation than another. The seminal animalcules form a natural ingredient of the fluid secreted in the testicle at the time when it is excreted for the purposes of propagation ; they appear to be invariably present, but addi- tional experiments are still wanting to prove them to be the active or essential agents of fecundation, much more the rudiments of the new being within the ovum. 6th. Like others of the operations of the animal economy, the action of fecundation is known principally in its effects; but it seems to be a question worthy of investigation whe- ther, in the phenomena exhibited during fecun- 468 GENERATION. elation, or the laws by which this change is regulated, it be in any respect analogous in its nature to the operation of certain poisonous or contagious principles, as for example, the venereal virus, vaccine matter, the contagious principle of small-pox, measles, scarlatina, plague, fevers, &c. The inimitable Harvey thus expresses himself regarding the essential nature of fecundation in different parts of the forty-ninth Exercitation on the efficient cause of the chicken. " Although it be a known thing subscribed by all that the foetus assumes its original and birth from the male and female, and consequently that the egge is produced by the cock and henne, and the chicken out of the egge, yet neither the schools of Physicians nor Aristotle's discerning brain have disclosed the manner how the cock and its seed doth mint and coine the chicken out of the egge." " This," he says, " is agreed upon by universal consent; that all animals whatsoever, which arise from male and female, are generated by the coition of both sexes, and so begotten as it were per contagium aliquod, by a kind of con- tagion." " Even also," he says, " by a breath or miasma," referring to the fecundation of the ova of fishes out of the body. " The lac maris, male's milk, propagating or genital liquor, vitale virus, vital or quickening venom," are all names of the seminal fluid of the male. Again, " The efficient in an egge, by a plastical vertue (because the male did only touch, though he be now far from touching and have no extremity reached out to it) doth frame and set up a foetus in its own species and resemblance." " What is there in genera- tion, that by a momentary touch (nay not touching at all, unlesse through the sides of many mediums) can orderly constitute the parts of the chicken by an epigenesis, and produce an univocal creature and its own like? and for no other reason but because it touched here- tofore." " The qualities of both parents are observable in the offspring, or the paternal and maternal handy-work may be tracked and pointed out both in the body and soul." The first cause must therefore be of a mixed kind. " It is required of the primary efficient in the fabrick of the chicken, that he employ skill, providence, wisdom, goodness, and understanding far above the capacity of our rational souls." 7th. In respect to the part of the female generative system at which fecundation takes place, it appears most probable that in quadru- peds and the human species this change occurs before the ovum reaches the uterus, or some way in the course of the Fallopian tubes ; perhaps most frequently in the upper part of them. There is, however, probably some variation among animals and in different cir- cumstances regarding this point. But while we state this as the conclusion most consistent with facts in the present state of our know- ledge, we ought not to omit the mention of the more prominent facts by which it is opposed. In some of the lower animals, fecundation seems to extend beyond the sphere of the ova which are ripe. In the Aphis (as was already mentioned at an early part of the paper) the production of young by the female goes on for several generations (eleven) without any sexual intercourse after that which gave rise to the first. In the Daphnia Longispina this is said also to be the case for twelve generations, and in the Monoculus pulex for fifteen. The queen-bee lays fruitful eggs during the whole year after being once impregnated ; and in the instance of the common fowl and some other birds, previously referred to more than once, if we reject the supposition of the seminal fluid remaining in action, it seems necessary to suppose that fecundation must occur in the ovary, since unripe ova are acted on by the fecundating medium at the same time with those which are arrived at maturity and are ready to descend into the oviduct.* Many physiologists also believe that the influence of the first impregnation extends to the products of subsequent ones. Thus Haller remarks that a mare which has bred with an ass and has had a mule foal, when it breeds next time with a horse, bears a foal having still some analogy with the ass. So also in the often cited instance of the mare which bred with a male Quagga, not only the immediate product, but three foals in subsequent breedings with an Arabian stallion, and these three even more than the first, partook of the peculiarities of the Quagga species. Instances of the same kind are mentioned by Burdach as occurring in the sow and bitch; and it is affirmed that the human female also, when twice married, bears occasionally to the second husband children resembling the first, both in bodily structure and mental powers. According to Hausmann, when a bitch has connexion with several dogs (and this is gene- rally the case during the continuance of the heat, sometimes to the amount of twenty,) she usually bears two kinds of puppies at least, and the greater number of these resemble the dog with which she first had connexion. We feel at a loss to decide what weight ought to be attached to these observations ; they appear to bear chiefly on the subjects which are discussed in the next part of this article. V. MISCELLANEOUS TOPICS RELATING TO THE PRECEDING HISTORY OF GENERATION. We have deferred until now the consideration of some topics which usually find a place in the history of the generative function, as we have thought it desirable to separate them from the preceding narrative on account of the vagueness of the facts and speculative nature of the opinions with which they are connected. The subject last discussed naturally leads to * Burdach hazards the opinion that in some quadrupeds the ova may not even be developed at the time of impregnation, as in the Roe-deer, which pair in July and August, but do not bear their young till May, and the Fox, the period of gesta- tion in which is much longer than we should sup- pose it ought to be, judging from the analogy of others of the Dog genus. GENERATION. 469 the first of these topics which we shall con- sider, viz. § 1. Superfatution. — In the first section of Part IV. it has been mentioned that in the human female, as soon as the ovum has arrived in the uterus, and even a short while before that period, the passage through the mouth and neck of the uterus is closed by a viscid mucus, which opposes a firm barrier against the entrance of seminal fluid, and thus prevents the occurrence of subsequent or reiterated con- ception. In some of the lower animals, on the other hand, it would appear that several consecutive conceptions not unfrequently occur, and in some animals this may be considered as the natural mode of generation. It becomes a point of some interest both in a physiological and in a medico-legal view to determine, whether, as has been supposed by some, the same ever takes place in the human species. The quadrupeds in which superfoetation (as a second conception during pregnancy is called) is said to occur possess a uterus with two horns, and it may be that in them the product of the first conception has occupied only one of the cornua of the uterus, and that the second conception occurred upon the other or empty side. This may be the case in the hare, for example, which is said to be particu- larly liable to superfoetation. In woman also, it has been supposed that a double form of uterus, which is present in rare instances as a malformation of that organ, may admit of a second conception on one side in the course of uterogestation confined to the other. But though this may be regarded as possible, we are not aware that any example of the actual occurrence of pregnancy in both cornua of a double uterus affords a satisfactory proof of it. Great caution is necessary in admitting the evidence of superfoetation, as many circum- stances concur to render it very fallacious. Women occasionally bear twins, or two chil- dren differing greatly in size and apparent age; and many are apt at once to form the conclu- sion from thence that the two children must have commenced their existence or have been generated at different times ; but it is much more likely in most of these instances, that the different appearance in the size and con- formation of the children has arisen solely from a difference in the rapidity and vigour of their growth. In by far the greater num- ber of such instances, the smaller of the children bears obvious marks of being stunted in its growth, and it is often deformed, blighted, or dead and shrunk ; and even although this were not the case and the children were both alive, a mere difference of size of children born at the same time must be regarded as very slight evidence indeed of so great a devi- ation from the usual phenomena of pregnancy as superfoetation. Those who believe in the possibility of the occurrence of superfoetation found their belief chiefly upon some rare instances of the birth of more than one perfectly developed child at successive periods so remote from one another that both cannot have been conceived at the same time, and it must be admitted that these cases, if correct, go far to prove the possibility of superfoetation. In reviewing the cases of alleged super- foetation two questions at once present them- selves for consideration, viz. 1st, whether a second conception may take place within a few hours or days after the first, or we may say at any period before the ovum is settled in the uterus; and, second, whether this may occur at a later period, as at two, three, four, or more months after the first conception. The puppies of a bitch, we have already mentioned, generally bear a resemblance to more than one of the dogs with which she has had connexion during the period of heat, and this period may extend to eight or nine days. A mare, which had been covered by a stallion, was five days afterwards covered by an ass, and bore at the usual time twins, one of which was a common foal, the other a mule.* Women have been known to bear two chil- dren of different colour; and in one of these instances the mother is said to have confessed to having admitted the embraces of a black servant a few hours after her husband, who was white. Facts like these seem to shew that sexual intercourse limited to an interval of a few days (most probably before the uterus has been closed by the decidua) may produce super- foetation. But we would remark that, although it may be that the mechanical obstruction of the decidua opposes an obstacle to the passage of semen upwards, or the descent of a new ovum into the uterus, there is obviously ano- ther cause why superfoetation should not occur : we mean that fundamental change in the con- stitution which is induced by pregnancy, similar to that which continues in the majority of women during lactation. But for such a constitutional change, we conceive continual derangement of the function of utero-gestation would attend that process in consequence of the recurrence of some of the more general symptoms of conception, even although a lodgement of a new ovum in the cavity of the uterus were impossible. The following cases serve to illustrate the nature of the more important facts on record which do not admit of an explanation, except- ing on the supposition that superfoetation has taken place. 1 . A woman bearing a full-grown male child had neither lochia nor milk after its birth, and a hundred and thirty-nine days afterwards bore a second child — a living girl, when the milk and lochia came naturally. Eisenmann, who had observed this case, explained the occurrence by supposing that a double uterus existed; but upon the woman's death some time afterwards, no unusual structure -was found.f * Archiv. Gen. torn. xii. p. 125. Another similar instance is related in torn. xvii. p. 89, of the same work. t See Burdach's Physiol. 470 GENERATION. 2. Desgvanges observed another instance in which a woman bore two girls at the interval of a hundred and sixty-eight days in the same circumstances as in the above-mentioned case.* 3. A third case is related by Fournier in which two girls were born at the interval of five months, there being lochia for a few days after the birth of the first.f 4. A fourth instance is mentioned of two children born at the interval of a hundred and nine days.J 5. Velpeau relates that a Mad. Bigaux had first a living child, and four and a half months, or a hundred and forty days afterwards, a second, also alive.§ We confess that we think these cases, if correctly reported, go far to prove the possible occasional occurrence of supeifcetation in the human species. On the supposition that two children born alive at different periods remote from one another have been conceived at the same time, three months appears to be the greatest extent to which the interval between their births could reach, the first being born prematurely at six and a half or seven months, and the second being retained in the uterus till the period of nine and a half or ten months; but this is improbable in some of the instances before us, as both children appeared equally complete, and no mere difference in the rate of their growth could account for their birth at so remote periods. We are reduced then to the necessity of ad- mitting the possibility, in very rare instances, of superfoetation ; but at the same time we may remark that the evidence regarding it is not sufficiently precise, and we are left entirely at a loss to explain what causes may give rise to this variation, and in what manner the seminal fluid may be supposed to pass through the uterus, or the new ovum to gain an entrance there. § 2. Influence exerted by parents on the qualities of their offspring in generation. — One of the most obvious and important laws of the reproductive function is that by which the specific distinction of animals is preserved. Like produces like ; and for the most part an undeviating succession of generations of simi- lar structure and qualities prevents both the extinction of any species and its being blended with or lost in any other. Numerous examples will recur to the mind of every one, of striking family resemblance, which point out in how many respects children frequently inherit their qualities from their parents ; but it must be held in remembrance that family or hereditary resemblance is seldom if ever complete, but * Diet, des Scien. Med. torn. liii. p. 418. % Ibid. torn. iv. p. 181. t Stark's Archiv fur die Geburtshulfe, &c. B. iv. S. 589. § Traite d'Accouchements, tom.i. p. 345, where cases are referred to by Pignot in the Bull, de !a Facult. 4e Annee, p. 123, by Wendt, Journal des Progres, torn. x. and Fahrenhorst, ibid. torn. viii. p. 161. only of that more general kind which belongs to the species. Thus in one family we re- cognise numerous, minute differences, and in fact it may be said that there are scarcely any two individuals of the same or of different family exactly alike. In respect to sex, the most obvious difference exists : the mother producing male and female; the son is not an exact copy of his father, nor the daughter of her mother, nor are they a mixture of both ; but each of them bears certain resemblances to one or other or to both of the parents, into which it may be interesting to inquire, — an in- vestigation which is to be regarded of some practical importance in reference to the breed- ing of cattle and other stock. As the female parent furnishes the greater part of the substance of the egg in all animals, and in viviparous animals provides also the materials which serve for the nourishment of the young with which it is intimately con- nected during utero-gestation, it might, a priori, have been supposed that the offspring should be more subject to be influenced by the qua- lities of the mother than by those of the father; but no general fact of this kind is established, and instances need not here be adduced which shew that the offspring, whether male or fe- male, bears nearly, if not quite, as many points of resemblance to the father as to the mother. Such influence as the male parent exerts upon the qualities of the offspring must be transmitted and take effect at the period of conception only, and the impression being that of the contact of the seminal fluid with the ovum must be momentary only. A cer- tain part of the female parent's influence is dependent on the original constitution of the ovum formed in her body, while another part of that influence may be supposed to extend through the whole period of utero-gestation. We shall first consider those instances of the transmission of hereditary qualities which appear to belong to the original constitution of the male and female generative products, and subsequently make some remarks on the influence which the female has been held to exert during the whole of pregnancy. The general structure of the body, the sta- ture, form, size of the bones, disposition to the formation of muscle, deposition of fat, or the reverse, seem to depend as frequently on the female as on the male parent in the human species. In some animals the male parent more frequently determines the size and general form of the body, as among feline animals, dogs, horses, &c. The bantam cock is said to cause the common hen to lay a small egg, and the common cock causes the bantam hen to lay a larger egg than usual. An enumeration of all the points of struc- ture which constitute family resemblance would detain us too long, and is unnecessary as they are familiar to every one. It does not appear to be satisfactorily established that the family resemblance is derived more from one than from the other parent, though in one family the influence of the one parent, and in another GENERATION. 471 family the influence of the other parent, may predominate.* Nor does it appear that any general law has been established regarding the transmission of the nature of the constitution, temperament, state of health, duration of life, &c; for in the human species at least these qualities of the offspring seem to be inherited from either parent or from both indiscriminately. The complexion and colour of the offspring has received much attention. In some animals the colour of both parents is sometimes pre- served, as in the piebald horse ; in others a mixture of the colours of the father and mo- ther appears in the offspring as an interme- diate tint. In other animals, and most fre- quently in the human species, the colour de- scends from one only of the parents. Thus among white races of the human species, it happens more frequently, when the parents are of different complexion, that the child takes after one or other of them than that its com- plexion is intermediate between those of the parents ; but it does not appear as yet to be ascertained that one parent determines the colour more frequently than the other. The offspring from the union of people of dark and white races of the human species usually has a complexion which is a mixture of or is intermediate between the complexions of the two parents, as in the Mulatto and other degrees of colouring; but it is alleged that in these instances the colour of the father usually pre- dominates over that of the mother. Thus a dark father produces with a white mother a darker child than a white father with a dark mother. Among animals there are infinite varieties in this respect. White colour is said to be more readily transmitted than others. In some animals, however, colour is trans- mitted with great regularity : thus it has been found that as many as two hundred and five of the product of two hundred and sixteen pairs of horses of similar colour inherited the colours of their parents. The degree of fruitfulness in bearing off- spring, or the opposite, sterility, the qualities of the voice, peculiarities in the degree of deli- cacy of the external senses, as long or short- sightedness, musical ear, &c, the physical powers of the body as illustrated in the speed or strength of horses, and peculiarities of the digestive functions of the nature of idiosyn- crasies, are other familiar examples of bodily qualities usually transmitted in hereditary de- scent from one or other parent to the offspring. Lastly, the qualities of the mind are, perhaps as much as the bodily configuration and powers, subject to influence from the hereditary in- fluence of parents upon their offspring. The powers of observation, memory, judgment, imagination, the fancy, and all that belongs to what is usually called genius, the emotions, * Br. Walker, in a short essay lately printed for private distribution, has attempted to shew that the upper and back part of the head usually resembles the mother, the face from the eyes downwards most frequently the father. passions, desires, and appetites, as inborn mental qualities of the offspring, are all liable to be influenced in the act of generation by the parents.* The hereditary predisposition of man and ani- mals to particular diseases also illustrates in a striking manner the general law now under con- sideration, and from its importance in reference to life assurance has attracted considerable at- tention. Almost all the forms of mental derangement are more or less directly hereditary, one of the parents or some near relation being affected. Of bodily diseases, pulmonary complaints, diseases of the heart, scrofula, rickets, worms, gout, rheumatism, hemorrhoids, hypochondri- asis, scirrhus, apoplexy, cataract, amaurosis, hernia, urinary calculi, may be mentioned as examples of diseases more or less directly transmitted as predispositions from parent to offspring. The goitral and cretinous affections combined with deficient intellect are striking examples of the effect of hereditary influence combined with that of the situation in which the cretins live. The union of goitrous per- sons in particular districts leads to the pro- duction of cretins, while the union of a cretin with a healthy person tends to the improve- ment of the offspring, or its gradual return to the healthy state. The predisposition to disease may be trans- mitted to the offspring from either parent, and from the one as often as from the other, but much more certainly when both the parents have been affected with the disease. We may also fhention, in connection with this subject, the transmission to the offspring of various marks and deformities in the struc- ture of the parents or their relations. The cretinism already mentioned is one of these, and there are numerous other cerebral de- formities which are so transmitted, as congeni- tal malformations, such as the acephalous and anencephalous states, spina bifida, cyclopia, &c. which run remarkably in particular families. In many instances the hereditary cause of these deformities has been distinctly traced to one or other of the parents. Naevus, moles, growths of hair in unusual places, hare-lip, deficient or supernumerary toes or fingers, have all been traced to hereditary influence, and probably as often to the one parent or his family as to the other. Malformations of the heart, congenital hernia, and indeed most other malformations, are capable of being traced to a similar origin. Were further illustration of this general law requisite, it would be found in the resem- blance of mules or hybrids produced by the union of two distinct races, varieties, or species of animals, which productions also afford an excellent opportunity of observing * In endeavouring to estimate the degree of original resemblance of offspring to parent mentally as well as bodily, but especially the former, great caution is necessary not to overlook that resem- blance between them which depends on education, similar habits, pursuits, mode of life, and conti- nual intercourse. 472 GENERATION. and comparing the amount of hereditary in- fluence exerted by one or other of the parents. The hybrid usually combines to a certain ex- tent the qualities of its father and mother, as in the familiar example of the common mule between the male ass and the mare, or in the product of the tiger and the lion, the dog and wolf, the pheasant and black grouse, the gold and common pheasant, and others. In some mules the qualities of the father predominate, in others those of the mother ; but so far as we are aware, the isolated facts regarding this point have not yet been brought under any general law. It has been asserted that acquired qualities, whether mental or bodily, of the parents are capable of being transmitted to their offspring. Thus the superiority of a civilized over a bar- barous nation is said to depend, not solely on the influence of an advanced state of educa- tion upon each new comer, but also on the greater natural powers of the children, derived from their parents at the moment of their production, or, in other words, the greater capability of the children to receive the higher mental acquirements and more refined ideas belonging to the civilized condition of society. Farther, it is asserted that dogs and cats which have accidentally lost their tails have brought forth young ones with a similar de- formity. Blumenbach affirms that a man who had lost his little finger had children with the same defect. A wound of the iris and a defor- mity of the finger occasioned by whitlow are said to have been transmitted. The well-trained pointer of this country produces a puppy much more capable of being trained than the dogs of the original breed. The retriever spaniel and the shepherd's colly are said to do the same. Well-broken horses produce docile foals, and lastly, the young of foxes living in hunting countries are naturally much more circumspect than those living in countries where they are not exposed to the danger of pursuit. We look upon all these alleged facts with distrust. Many of them are coincidences; others, we suspect, are false. It is obviously insufficient for our purpose to ascertain the qualities of the one generation which is born. We must also know to what circumstances the parent may have owed its peculiarity. We feel convinced that education more than any other circumstance has influenced the superior powers of the animals above alluded to, and there is no proof that the parent did not possess the same capabilities or natural powers as the offspring. There are, on the other hand, innumerable instances which shew that acquired alterations of structure are not transmitted. How many men are there who have lost limbs and yet have produced children in no respect maimed. A quadruped without the fore-legs has borne entire young. A bitch in which the spleen had been extirpated had young possessing that organ. Men with only one testicle have sons with the usual number ; and lastly, the people of nations, the males of which have been cir- cumcised during hundreds of years, have chil- dren with foreskins not a bit shorter than those of nations in which no such practice exists. The breeding of domestic animals of dif- ferent kinds, suited respectively to the various useful purposes for which they are employed, is a subject connected with the present question of high practical importance ; but unfortu- nately, though some practical men have well understood the proper method to be pursued, it is to be regretted that the facts have never been reduced to general rules, and that the theory has been almost entirely neglected. It is generally admitted as a fact proven that in the ox, horse, and other domestic animals the purer or less mixed the breed is, there is the greater probability of its trans- mitting to the offspring the qualities which it possesses, whether these be good or bad. Economical purposes have made the male in general the most important, simply because he serves for a considerable number of females. The consequence of this has been that more attention has been paid to the blood or purity of race of the stallion, bull, ram, and boar than to that of their females ; and hence it may be the case that these males more frequently transmit their qualities to the offspring than do the inferior females with "which they are often made to breed. But this circumstance can scarcely be adduced as a proof that the male, caeteris paribus, influences the offspring more than the female. Bad as well as good qualities may be trans- mitted, and, therefore, it is obvious that in endeavouring to improve any stock by engraft- ing a good quality, the breeder must choose a male which, besides the requisite good quality, is free from those defects of the female which it is desirable to sink. He must also select a male in the family of which the desired quality has been long resident. He cannot engraft the quality all at once, but must endeavour to introduce it by frequent crossing. In the horse, for example, the strength of bone and weight of muscle suitable for slow draught, the light frame and prodigious swift- ness of the race-horse, and the intermediate or rather combined qualities of the carriage-horse, hack, or hunter, are all capable of being pro- duced by proper attention to purity or mixture of breeds. The pace, speed, action, temper, courage, colour or quality of hair, and almost all other qualities may be increased, dimi- nished, or altered by a judicious admixture of different races. So also the immense weight of beef and fat of the large ox, the flavour of the flesh, the abundance or richness of the milk of the cow, are subject to modification in every different breeding. The economical breeder, then, while he has settled in his mind the object which he wishes to accomplish in any of his stocks, must hold in recollection that it is only by the combi- nation and continued succession of good qua- lities that he can ensure a permanent improve- ment. He must not expect to be able to effect this by crossing the breed of an impure blooded or worn-out female with a male of GENERATION. 4T3 superior qualities. Bad qualities may become fear that the mind, with all its peculiar tastes, as fixed as good ones, and a judicious selection prejudices, and passions, has too much to do of the good ones (as adapted for his purpose) with the greater number of matrimonial al- ought to be his first and principal object.* liances to allow physiological considerations A belief exists with some, founded, it is much jurisdiction, said, both on common observation and scien- From the different facts now touched upon, tific research, that frequent breeding in the it is obvious that the original type of the parents same family, or what is commonly called modifies that of their offspring; while, in gene- breeding in and in, has the effect of deterior- ral, varieties accidentally acquired do not pass ating a race. There appears, however, much in hereditary descent, unless they are of such a reason to believe that the opinion just now nature as to constitute a permanently distinct stated is founded in error. In a state of nature race or variety. it not unfrequently happens, among those ani- In the mixture of different races of the human mals especially which do not pair, that the species and of distinct species of animals we strongest males take precedence of the weaker, recognise a constant tendency in succeeding and naturally select the finest females (as generations to return to the original type or pure occurs in the deer); but in a state of domes- breed; an effect which seems to proceed natu- ticily this cannot always be the case, and rally from the general law already announced, inferior animals coming together give rise to that the purer the breed of either of the parents, inferior offspring; but, if in the farm-yard or in other words, the more nearly it approaches sufficient care be taken in the selection of the the original type or unmixed race, the more breeding males and females, it does not appear readily will its qualities descend to the off- that near relationship has any effect in dete- spring . When the mixed offspring of the black riorating the race, nor in impeding the trans- and white races of men unites with either the mission of good qualities which may be found black or the white, the offspring in successive in males and females of the same family. generations becomes more and more nearly The belief now alluded to has been held in allied to the pure breed with which the cross is relation to the human species also, and it is made, and at last wholly identified with it. affirmed that both the bodily and mental qua- We must look upon this general law of the lities of the offspring suffer gradual and pro- tendency of all mixed varieties to return to the gressive injury from the continued mixture of original type, together with the circumstance that successive generations of the same family or a hybrids rarely breed as means adopted by na- small number of families. Hence we find ture for the preservation of distinct species, that the marriage of cousins-german, which The transmission of hereditary resemblance, is according to law in this country, is repro- either as regards the general structure of the bated as prejudicial by some; and various body or peculiarities, is not, however, invan- royal families and aristocratic families are re- able, nor always immediate from parents to off- ferred to as examples of the bad effect of spring. Thus parents with certain deformities the restriction of conjugal union to a narrow may produce all their children naturally formed circle. and healthy ; or some of them only (in one It must be remembered, however, that the case the males, in a second the females, in a mutual selection of the parents is not quite the third some of both sexes) may inherit the ab- same in the human species as among the lower normal peculiarity, while the rest of the chil- animals ; and in the examples just referred to dren are healthy. But these healthy children, we feel even inclined to doubt whether, when from some disposition of their constitution, may due allowance is made for the nature of their transmit to their descendants either in the first education, it will be found that kings or or in a subsequent generation the defect which princes have become worse or less talented existed in their parents. The varieties in this re- in modern than in ancient times, or whether spect in the human species are almost infinite, among that class there is, on an average, a Thus, in one family all the children resembleone greater proportion of stupid men than in other parent in a striking manner ; in another the ranks of society. male children take after the father chiefly, the The regularity of feature and beauty of the females after the mother ; and in a third the Persian race has been greatly improved by converse holds, the peculiarities of the father their choice of the most beautiful Circassian descending principally to daughters, those of and Georgian wives ; and there are many the mother to sons,- — an arrangement of family examples of particular families in this country resemblance which is the most commonly pre- in which regular and handsome features and a valent according to M. Girou, who endeavours well-knit and fully developed form of body to shew that family resemblance frequently are hereditary. We shall not pursue the at- passes in an alternating manner from grand- tempt, however, which some have made to parent to grandchild. Thus, the grandchild apply the principles of cattle-breeding to the resembles the grandparent of the same sex, so human species ; for however desirable and that a boy whose father is like his (the father's) necessary an improvement of the breed may mother resembles most the grandfather, as in appear to some Utopian philanthropists, we the following plan. ^st Generation. Grand/. Grandm. Grand/. Gramlm. 2d ditto | Father Mother | 3d ditto Son Daughter Son Daiifrh. If it should be proved that a first or earlier 2 I * We refer the reader to the Farmer's Series of the Library of Useful Knowledge. Vols. Horse and Cattle. vol. ir. 474 GENERATION. impregnation influences the product of a sub- sequent one, in breeding any particular stock of animals, it would appear of importance that the female should always breed with well qua- lified males; and farther, that the genealogy of both parents for one step, if not more, back- wards, ought to enter as an item into the cal- culation of the probable qualifications of the offspring. Much information is, however, still wanting on this subject, which, as it involves the most obscure parts of the generative process, we can hardly expect ever to be able to fathom. It cannot but be a matter of wonder and extreme interest to inquire how, in the unformed germi- nal spot of the egg of the female at the moment when it receives the vital fecundating influence of the male semen, the disposition to the forma- tion of those minute modifications of structure and function which constitute hereditary re- semblances is capable of being retained and transmitted to the future offspring. The celebrated Darwin and some other fan- ciful speculators on physiological subjects held an opinion* that the transitory state of the minds of the father or mother at the instant of conception has a marked influence on the men- tal and physical qualities of the offspring. Thus it has been alleged that children begotten after debauchery or drunkenness are liable to idiocy or weakness both of mind and body ; that when the amorous propensities are too much excited, the offspring runs the risk of erring in the same way ; and in short, that ac- cording to the predominance of one or other sentiment, propensity, or frame of mind, the offspring may be a genius or a dolt, a sentimen- tal swain or an unfeeling brute, a thief, a rob- ber, a murderer, &c. Leaving to others the proof or disproof of the alleged facts upon which the above-mentioned belief is founded, we would take the liberty of expressing our doubts as to whether at the particular time alluded to by these theorists any idea but one is usually predominant. Nor shall we here dwell upon the obvious local treatment which is applicable upon the phrenological view of the subject; but as few may be aware of the real importance of that critical period in which life is conferred upon a new being, we have thought it right to put our married readers at least upon their guard against unrestrained yielding to any of the baser feelings or ideas, which do creep into the best-regulated establishments, requesting at the same time that they will communicate to their partners such information as may be con- sidered necessary for the attainment of the grand object in view, viz. the improvement of the po- pulation of this kingdom. The belief now stated as regards the human species has also been applied to animals, and that either parent may thus influence the off- spring. Thus it is asserted that the male race- horse when excited by running, if not fatigued, is in the best condition for communicating speed to his offspring. Again, it is related that at * More recently adopted by Mr. Combe, of Edin- burgh, in his Work on the Constitution of Man. the time when a stallion was about to cover a mare, the stallion's pale colour was objected to, whereupon the groom, knowing in the effect of colour upon horses' imaginations, presented before the stallion a mare of a pleasing colour, which had the desired effect of determining a dark colour in the offspring. This is said to have been repeated with success in the same horse more than once. As a similar case, the influence acting through the mother, it is related that a cow belonging to a farmer of Angus, in Scotland, had been grazing in company with an horned ox of a black and white colour for some time before it came into heat. The bull which impregnated the cow Had no horns, and differed totally from the ox in colour, as did also the cow itself ; and yet, wonderful to ralate, the next calf was black and white, and had horns. These stories lead us to the consideration of a host of extraordinary relations, from which the general conclusion has been drawn, by no very logical process of induction, that the imagina- tion of the female parent is capable of exerting a powerful influence on the structure and qua- lities of the offspring either at the moment of conception or during part of the period of utero- gestation. The effects of the mother's imagination upon the child are so various that we cannot hope to be able to reduce them to any general or com- plete enumeration. Those which have attracted the greatest share of attention are of the nature of blemishes, spots, wounds, deficient and re- dundant parts, in short, all unnatural or so- called monstrous formations of the child. The alleged causes of these unnatural for- mations include all those circumstances which powerfully excite the moral faculties, the fancy, desires, or passions of the mother ; sudden surprise, fear, anger, horror or disgust on her being a witness of any unusual or frightful event or object, or the opposite pas- sions of joy, pleasure, admiration, &c. as well as strong longings, desires, and appe- tites, whether satisfied or not. The influence of the mother's imagination upon the child is not confined in its effects to bodily disfigu- ration or change, however, for those who carry their belief its whole length hold that the mind of the child may also be similarly modified. Thus it is stated that the ambition, courage, and military skill of Napoleon Bonaparte had their foundation in the circumstance that the empe- ror's mother followed her husband in his cam- paigns, and was subjected to all the dangers of a military life ; while, on the other hand, the murder of David Rizzio in the presence of Queen Mary was the death-blow to the personal courage of King James, and occasioned that strong dislike of edged weapons for which that crafty and pedantic monarch was said to be re- markable. We can readily believe that all sudden or violent changes in the functions of the mo- ther, deranaements of the general circulation, nervous affections, and other circumstances which tend to disturb the uterine function, must cause or be liable to occasion injury to GENERATION. 475 the foetus or its coverings during pregnancy. So also we can understand that any violent affection of the mind of a pregnant woman, in so far as it tends to derange the bodily func- tions, may produce some effect on the nutrition of the child. Some contagious diseases pass from the mo- ther to the child in utero. Syphilis and small- pox may be mentioned as those the effects of which have been most frequently observed.* Typhous fever, on the other hand, is said rarely to affect the child. We know also that severe affections of the mother may cause the death of the child, and its premature expulsion or abor- tion. According to Hausmann, the effect of variations of the external atmosphere is visible in the unusual number of blind colts and hydro- cephalic pigs which are born after a wet sum- mer. Malformations of the fcetus of birds have been artificially produced by external injuries and altered position of the eggs during incuba- tion, f The transmission to the child of the effects of chemical poisons taken by the mother has also been observed ; but in all the foregoing the effect of the injury has been more or less general ; and there is no sufficient reason to conclude from them that a particular impres- sion on the mind of the mother is capable of producing physical injury, or a particular de- formity in one or other of the organs of the foetus. A vague notion is entertained by some that a certain influence is exerted by the hen or other bird on the eggs that they incubate, by which the qualities of the progeny are modified. But we must observe that hereditary resemblances are preserved in artificial incubation without the hen ; and although we are disposed to ad- mit that the female bird incubates its eggs with an instinctive care and perfection that art can rarely imitate, we are exceedingly sceptical as to the possibility of any other secret influence from the oviparous mother to its offspring once the eggs have left the body ; and the attempt to support the theory of imagination by this opinion is an explanation of the obscurum per obscurius. Were it possible to separate the better authen- ticated from the more fanciful relations of the effects of the mother's imagination, or to select those instances only in which the impression on the mind of the mother had been carefully noted before the birth of the child, we might expect in some degree to be able to free this question from the falsity and prejudice which obscures it. But such a separation we believe to be impossible, and we have therefore re- solved to enumerate shortly some of the more remarkable cases taken at random, \ from which * In reference to this, it is an interesting circum- stance that the child is affected with small-pox some time after the mother, as if the contagion had taken the same time to operate as it does in passing between two persons. t As in Geoffory St. Hilaire's experiments, which the author has more than once repeated with a si- milar result. i From Burdach's Physiologic, 15. ii. and from a talented Refutation of the Doctrine of the Imagina- we think the reader will best be able to judge what value or faith is to be attached to the facts now under consideration. In a certain number of these cases we are told that an injury of an organ in the mother causes a similar injury in a corresponding part of the child's body ; as in the following ex- amples. 1. A cow killed by the blow of a hatchet is found pregnant of a fcetus with a bruise on the same place of the forehead. 2. The same was the case with the young one of a hind that had been shot. 3. A pregnant cat which had had its tail trodden on bore five young, in four of which the tail was similarly wounded. 4. A woman bitten on the pudenda by a dog bore a boy having a wound of the glans penis. This boy suffered from epilepsy, and when the fits came on during sleep was frequently heard to call aloud, " the dog bites me ! " There are other similar cases on record. 5. A pregnant woman walking with a friend has her head knocked violently against her friend's, and shortly afterwards bears twins, which are joined together by the foreheads. 6. A gentlewoman who was cut for rupture in the groin during her pregnancy, bears a boy having a large scar in the same region, which he bore for thirty years afterwards. The injuries of others operating on the ima- gination of the mother may affect the structure of the child : thus — 7. A woman who was suddenly alarmed by seeing her husband come home with one side of his face swollen and distorted by a blow, bears a child (a girl) with a purple swelling covering the forehead, nose, &c. of the same side. 8. A child is born with hare-lip, which was caused by the mother's frequently seeing a child with the same deformity during her preg- nancy. 9. A mother seeing a criminal broke upon the wheel, bears an idiot child, of which the bones are similarly broken. 10. A woman seeing a person in an epileptic fit brings forth a child which is subject to epilepsy. 11. A lady in London, who is frightened by a beggar presenting the stump of an arm to her, bears a child wanting a hand. 12. A child is born with its head pierced, in consequence of its mother having seen a man run through the body with a sword. 13. A woman is forced to be present at the opening of a calf by the butcher. She after- wards bears a child with all the bowels hang- ing out of the abdomen. This woman was at the time of the accident aware that something was going wrong in the womb. 14. A similar misfortune happened to the child of another woman, who was imprudent enough to witness the disembowelling of a pig during her pregnancy. tionists, by Dr. Blundell, of London. Professor Burdach, we may remark, is inclined to adopt the belief. 476 GENERATION. The mere description of an event may affect the child, as in the following curious case. 15. A woman who had listened with con- siderable interest to a description of the ope- ration of circumcision bears a child with the foreskin split up and turned back ! 16. A woman who sees another affected with prolapsus uteri bears a child affected with the same disease. The examples of the effect of sudden fright, disgust, anger, joy, &c. are very numerous. 17. A lady absent from home is alarmed by seeing a great fire in the direction of and near her own house ; and some months afterwards bears a female child having the distinct mark of a flame on her forehead. 18. A pregnant woman frighted by her hus- band pursuing her with a drawn sword, bears a child with a large wound in the forehead. 19. A man who had personated a devil (or satyr according to other authorities) goes to bed in his assumed dress, and his wife, being then pregnant, afterwards bears a child having horns, cloven feet, &c. 20. A mother frighted by the firing of a gun has a child wounded as by a gun-shot. 21. A pregnant woman falls into a violent passion at not being able to obtain a particular piece of meat at a butcher's shop ; she bleeds at the nose, and wiping the blood from her lip, afterwards bears a child wanting the lip. 22. A woman two months before being brought to bed is alarmed by hearing a report that a neighbour had murdered his wife by a wound on the breast, and bears a child with a similar wound. 23. A child is born with the hair of one side black, that of the other white: competent judges declared at the time that both sides would have been white, but for the circum- stance that the mother had carried a heavy sack of coals during her pregnancy. 24. A woman frighted by the sudden ap- pearance of a negro brings forth a child with various black marks. 25. A mother is suddenly frighted by a lizard jumping into her breast, and afterwards gives birth to a child having a fleshy excre- scence exactly like a lizard growing from the breast, to which it adhered by the head or neck. 26. A child has a face exactly like a frog's, from the mother having held a frog in her hand about the time of conception. 27. The remarkable resemblance of a wo- man to an ape was fully accounted for by her mother having been much pleased with one of these animals when with child of her. The effect of the attentive contemplation of pictures, statues, &c. by pregnant women is worthy of notice. 28. A chi^d is born covered with hairs in consequent' of the mother having been in the habit of "beholding a picture of St. John the Baptist. 29. A woman gives birth to a child covered with hair and having the claws of a bear, from her constantly beholding the images and pic- tures of bears hung up every where in the dwelling of the Ursini family, to which she belonged. It is not stated by the Author of Waverley, whether any thing of the kind ever happened in the Bradwardine family. 30. A woman contemplating, too earnestly as it appears, a picture of St. Pius, has after- wards a child bearing a striking resemblance to an old man. 3 1 . The tyrant Dionysius was aware of the effect of pictures ; for he hung a beautiful picture in his wife's chamber, in order to im- prove his children's looks. 32. Two girls (twins) were born with their bodies joined together, their mother having during her pregnancy been in the habit of at- tentively contemplating two sacred images similarly placed. 33. A child is born with its skin all mottled in colour from the mother having made a visit to St. Winifred's Well, and seeing the red peb- bles there. 34. Another child was marked on the face, in consequence of the mother having worn black patches. The longings and depraved appetites to which pregnant women are liable are occa- sionally the causes of marks and deformities in their children. 35. There are a great many instances in which the longing of the mother after straw- berries, grapes, cherries, peaches, and other fruits has caused the growth of tumours in the children exactly resembling in each the fruit that was wished for, 36. A woman who had longed for a lobster brings forth a child much resembling one of these animals. 37. Another woman had a female child, the head of which was like a shell-fish (a bivalve, which opened and shut as a mouth), which proceeded from the mother's having had a strong desire for mussels at one time of her preg- nancy. 38. A pregnant woman longs, or has a great desire to bite the shoulder of a baker who happens to pass. The husband, wishing to humour this extraordinary fancy, hires the baker to submit to be bitten. The mother makes two bites, but of such a kind that the baker will not submit to more; and some time after- wards she is brought to bed of three children, one dead and two living. 39. A case of spina bifida near the sacrum is explained by the mother's having wished for fritters, and not obtaining them, having ap- plied her hand (we know not with what object) to a corresponding place in her own body. The impression on the fancy of the mother may be made before conception has taken place : thus — 40 A woman, whose children had pre- viously been healthy, six weeks before con- ception is suddenly frighted by a beggar who presents a stumped arm and a wooden leg, and threatens to embrace her : the next child had only one stump leg and two stump arms. The impression on the fancy may extend to the product of several successive conceptions. 41. A young woman frighted in her first GENERATION. 477 pregnancy by the sight of a child with hare-lip, bears a child with a complete deformity of the same kind : her second child had merely a deep slit, and her third no more than a mark in the same place. We do not wish to argue against this hy- pothesis from its prima facie absurdity merely; but we think it will be generally admitted that the greater number of the foregoing cases are ridiculous and incredible ; inasmuch as simple malformations of structure well known to ana- tomists have been rfgarded as the represen- tations of animals and other objects to which they bear a very distant if any resemblance, — cases, in short, in which it is apparent that the imagination of the bye-standers has been more active than that of the mother. We shall at once admit that we ought not to reject immediately an explanation of the me- chanism of a vital function on account of its obscurity merely ; but we assert that the gene- ral phenomena of the vital functions are capa- ble of being observed and reduced to fixed and general laws, which is certainly by no means the case with the effects of imagination, which are as various and contradictory as they are absurd and ridiculous. The anatomical connection of the maternal uterus and child is so well known that we may with safety affirm that no such communication exists as would be necessary for the transmission of an im- pression from the body of the mother to any particular organ of the foetus, and much less any means of conveying mental impressions only. The longings which are said to be so liable to cause injuries of the child seem to act in the same manner whether the appetite is satisfied or not, &c. But moral reasons are much stronger against the belief. It is obvious that in much the larger proportion of the cases related, the co- incidence of the mental impression on the mother with the injury done to the child is a post-partum observation and discovery. The mother and her friends, or the father, if such a deformity shall belong to his side of the house, are desirous of finding an explanation of the blemish which shall not be a stigma upon them; and in other instances it is to be feared that the idle and talkative women who attend upon child-beds, and even more scientific male accoucheurs, have encouraged the mother's belief in the effect of some alleged previous impression (selected from thousands) on her imagination, in order to hide undue violence employed during the delivery, or perhaps with a less culpable desire to quiet the fears of the mother while in the dangerous puerperal state. There is no doubt that there are innumerable instances in which the imagination and all the moral and intellectual powers of women have been highly excited during pregnancy without their children having suffered in any respects ; and there are not wanting instances of chil- dren being born with all kinds of deformity that have been attributed to the effect of imagination, without their being aware of any unusual impression having been made on their minds. Again, it may be remarked that the stage of the period of pregnancy at which the injury of the child may take place is by no means de- fined, and that there is no correspondence between the time or advancement of the foetus and the nature of the injury. Some injuries are said to have occurred or to have had their foundation laid at the very moment of con- ception, and even occasionally before that time, while others are inflicted only a few weeks be- fore birth. The monstrous appearances or malformations which constitute by far the greater part of the injuries attributed to the mother's imagination, are now no longer regarded as lusus naturae merely, or " sports of nature's fancy," as they used to be called ; but the times at which many of them must have occurred are known with some degree of certainty, and these times by no means correspond with the periods at which the imagination is said to have been affected. Besides this, nearly the whole of congenital malformations have been accurately anatomised, and their structure is reduced to general laws as regular and determinate in each individual form as the more usual or so- called natural structure. See Monstrosity. In this question, as in others of a like kind, reference has been made to scriptural autho- rity, in the history, viz. of Jacob's placing the peeled black and willow rods before the ewes which went to drink and afterwards conceived. But any one who pays the slightest attention to the whole of this relation will at once be convinced that the sacred writer, in describing the proceeding of Jacob, exhibits merely that patriarch's belief in the efficacy of such means; for in a subsequent part of the chapter Jacob is undeceived by the angel, who appears to him in a dream and informs him of the real cause of the multiplication of the speckled lambs, &c. viz. the circumstance that the ring-straked, speckled, and spotted males had leaped upon the females, and that the progeny therefore merely inherited their colour from their fathers. We now leave this unsatisfactory subject, upon which we have perhaps dwelt longer than it deserves. We have introduced the foregoing remarks partly in accordance with custom, and also with a view to shew how little connection exists between the facts of our subject and the vague fancies to which allusion has been made. In doing so we are aware that we are liable to the accusation, on the one hand, of having treated with too much levity facts and ob- servations upon which some are disposed im- plicitly to rely, and, on the other, of trifling with science in noticing even such vain fancies as belong to pregnant women and their atten- dant nurses. We conclude by adopting and expressing the opinion of Dr. Blundell, " that it is con- trary to experience, reason, and anatomy to believe that the strong attention of the mother's mind to a determinate object or event can cause a determinate or a specific impression upon the body of her child without any force or violence from without; and that it is equally improbable that, when the imagination is ope- 478 GENERATION. rating, the application of the mother's hand to any part of her own body will cause a dis- figuration or specific impression on a corres- ponding part of the body of the child." § 3. Number of children ; and relative proportion of the male and J'emale sexes. The simpler animals are, generally speaking, more fruitful than the complicated ones. As examples of great fecundity, may be mentioned some of the Entozoa and Mollusca, which pro- duce hundreds of thousands of ova ; among Crustacea and Insects some produce many thousand young. The Perch and Cyprinus genus among fishes produce some hundreds of thousands, and the common Cod, it is said, some millions of ova. Most of the Batrachia produce at least some hundreds. But in the warm-blooded Vertebrata, the necessity of in- cubation or utero-gestation puts a limit to the number of young ; and there are also compara- tively few in the Blenny, Skate, Shark, Land Salamander, or such animals as are ovo-vivi- parous. In the humau female, the number of chil- dren altogether produced is limited, first, by the number of Graafian vesicles in the ovaries, which usually amounts to from twelve to fif- teen in each ovary ; and second, by the length of the time during which a woman bears chil- dren, (the greatest extent of which is usually twenty-five years, that is, from the age of fifteen to forty, or twenty to forty-five,) the length of this period again depending upon the rapidity with which the births succeed one another, and the number of children produced at each. Women most frequently bear every twenty months, but some have children at shorter in- tervals, as of fifteen or even twelve months. This often depends upon the circumstance that in some lactation prevents conception ; in others it does not. The number of the eggs of birds for one in- cubation varies from two to sixteen. The num- ber of the young of Mammalia produced in one utero-gestation varies from one to fifteen, and occasionally more. Woman usually bears a single child. The proportion of twin-births to those of single children is estimated by Burdach as one to seventy or eighty : the proportion of triplet births one to six or seven thousand ; quadru- plets, one to twenty or fifty thousand. Occa- sionally five children come at one birth, and there are instances on record of six or even seven children being born at once. The causes of this greater or less fecundity are not known : they are in all probability various; being not of an accidental nature, but connected with the constitution of one or other of the parents, most frequently per- haps of the mother. A healthy woman bearing during the whole time, and with the common duration of inter- val, may have in all from twelve to sixteen chil- dren ; but some have as many as eighteen or twenty ; and when there are twins, &c. con- siderably more, as in the following remarkable instances. First, eighteen children at six births. Second, forty-four children in all, thirty in the first marriage, and fourteen in the second ; and in a still more extraordinary case, fifty-three children in all in one marriage, eighteen times single births, five limes twins, four times tri- plets, once six, and once seven.* Men have been known to beget seventy or eighty children in two or more marriages, but the tendency of polygamy is generally believed to be to diminish rather than to increase the number of the whole progeny. According to Marc, not more than two or three children are born from two thousand pros- titutes in the course of a year, — a circumstance depending in part on their want of liability to conception, and in part on frequent abortion. The proportion of children born in each mar- riage varies much in different countries. The following statement of the average number is taken from Burdach : Germany, 6 — 8 ; Eng- land, 5 — 7; France, 4 — 5; Spain and Italy, 2— 3.f In reference to the average proportion of male and female births, it appears from very exten- sive data that in this and most other countries the number of males usually exceeds that of females ; in this country in the proportion of four or five in a hundred. The circumstances which influence the pre- ponderance of male births are not known. The accompanying table shews how very constant it is in different countries. Table of the proportional number of males and females born in different countries ; the females being taken as 100. Great Britain 104.75 ^ f 106.55 FranCe ( 103.38 Prussia {ISqo Sweden 104.72 Wurtemburg . . 105.69 Westphalia and Rhine .... 105.86 Bohemia 105.38 Netherlands 106.44 Saxony and Silesia 106.05 Austria 106.10 Sicily 106.18 Brandenburg 106.27 Mecklenburg 107.07 Mailand 107.61 Russia 108.91 Jews in Prussia 112. in Breslau 114. in Leghorn 1 20. Christians in Leghorn 104. It has been found, on the other hand, that the first children of a marriage consist of a greater number of females and fewer males, in the pro- portion, according to Burdach, of fifty-three male births to a hundred females. A similar preponderance of females is said to exist among illegitimate children ; but the difference is ff See Fournier, Diet, des Scien. Med. torn iv. + According to Burdach, one marriage out of fifty is unfruitful ; there is one birth on an average for every twenty-five of the population of a place ; and taking the whole population of the world at six hundred and thirty-three millions, about fifty-one children are born every second ! GENERATION. 479 much less, not amounting to move than four or six in one hundred.* Malformations are said to occur more fre- quently among illegitimate than legitimate chil- dren ; and malformed children are more fre- quently of the female sex. This, together with the circumstance that illegitimate children are oftenest first born, may in some degree account for the greater number of females among them. The data upon which it has been attempted to found an explanation of the cause of the formation of a male or female offspring are very slender indeed ; nor are we likely ever to ob- tain knowledge which shall enable us to form a satisfactory theory regarding the cause of the determination of the sex. Some men beget always male children, others always females, in more than one marriage. The same seems sometimes to depend on the mother. In other marriages children of one sex are born for a time, and subsequently those of the other ; or the male and female children may alternate, &c. 8cc. without our being able to point out any circumstance which has given rise to the pro- duction of one or other sex. Accordingly many vague opinions have been entertained regarding this subject, as for exam- ple the following : 1. That the wishes or ideas of the parents at the time of conceptions may influence the sex of the offspring. 2. The nature of the food of the parents, par- ticularly of the mother during pregnancy. 3. The use of various medicines : hence the numerous charms and recipes for begetting children of either sex. 4. The quantity of oxygen absorbed during development. 5. The manner in which the spermatic artery is given off from the aorta, and 6. The older and equally groundless notion that male children come from the right testicle or ovary, and females from the left ; upon which hypothesis was founded the celebrated advice of Hippocrates : " Ubi femellam gene- rare volet (pater) coeat, ac dextram testem obli- ge!, quantum id tolerare poterit, sed si ma- rem generare appetat, sinister testis obligandus erit." A belief has long prevailed that the greater the strength of either of the parents in propor- tion to the other, the more of its own sex will be generated. M. Girou de Buzaraignes has paid considerable attention to the influence of age, strength, mode of life, &c. of the parents on the sex of the offspring, and has made a series of experiments on the domestic animals, from which, should they be confirmed, some important results may be expected. According to M. Girou,-|- male fathers among the domestic animals which are either too old or too young, produce with mature and healthy females more female than male offspring ; while female parents that are too old or too young in proportion to the males bear most males. This * Illegitimate Children . Legitimate ditto t Sur la Generation. France. Prussia. Hamburg. Buys. Boys. Boys. Girls- ..104- 102- 94-, .106- 106- 105 / 100 would appear to be the case in the human species also from the observations of Hofacker at Tubingen, and of Saddler on the English peerage : the children of a husband consider- ably younger than his wife being nearly in the proportion of ninety sons to a hundred daugh- ters ; while those of the husband considerably older than the mother are in the proportion of a hundred and fifty or a hundred and sixty sons to a hundred daughters ; the intermediate ages being found to give a proportionate scale. Burdach states that those women who are most fruitful bear many more boys than girls, as in the following examples : — Boys. Girls. 1st woman bore 26 6 2nd ditto, in first marriage .... 27 3 in second ditto 14 0 3rd ditto 38 15 According to Girou, female domestic animals bear more females when well nourished and left in repose than when much worked and on spare diet ; and it has been alleged that the sexes of plants are influenced by their nourish- ment or soil in which they grow ; dioecious plants having seeds which propagate more males in dry ground exposed to the sun, more females in moist, well manured, and shady ground ; monoecious plants bearing more of the staminiferous or pistilliferous flowers in cor- responding circumstances. XQ^J- — The explanation of the cause of this variation of the sex as well as of the original sexual dif- ference, it has already been remarked, is beyond the reach of investigation. Very interesting observations have, however, brought to light the different steps of the process by whicli the generative organs of either sex are gradually formed during the development of the foetus; and a series of facts has thus been established of great interest and importance as tending to elucidate the nature of those numerous remark- able malformations of the reproductive organs generally comprehended under the term Her- maphrodism. We refer the reader to the article upon this subject, and to that of Ovum, for a history of the process now alluded to, and shall not do more than merely mention in this place some of the more important results which have been obtained. 1st. It appears that in the earliest stages of foetal life, the sexes (or what may become afterwards either male or female, that is, all the young) are perfectly alike in structure. 2nd. That there exists in all a common ma- trix or rudimentary organ or set of organs, which at a later period is converted by deve- lopment into the male or female organs. 3rd. That the early type of the sexual organs is to be regarded as common and single, rather than double, as some have considered it. In conclusion, we may remark that we must confess ourselves equally unable to fathom the nature of the original bias or determination given by the parents, in consequence of which a male or a female child is produced, and to ascertain the manner in which any other here- ditary influence, quality, or conformation is transmitted from the parent to its offspring. At the same time it appears not improbable 480 GLAND. that the nature of the sex may in some degree be modified by circumstances affecting the female at an early period of utero-gestation. In reference to this subject we ought not to omit the mention of a fact which is well esta- blished, viz. that when the cow bears two calves, one of which is a male, the other, exteriorly re- sembling- the female, has its reproductive organs internally imperfectly formed, being of that kind of hermaphrodite formation usually called the Free Martin.* Bibliography. — Hofmann, G. De generatione et hsu partium, &c. 8vo. Altorf, 1648. Harvey, Guil. Excercitationes de generatione animalium, 4to. Lond. 1651. Malpighi, De formatione pulli in ovo, 4to. Lond. 1673; Ej. De ovo incubato, ib. 1686. Burtholinus, De form, et nutrit. foetus in utero, 4to. Hafn. 1687. De Graaf, De virorum organis generationi inservientibus, 8vo. Lugd. Batav. 1668 ; Ej. De muliemm organis, ib. 1672. Hartmann, Dubia de generatione viviparorura ex ovo, 4to. Regiom. 1699, in Haller, Diss. Anat. t. v. Trelincourt, De concepiione adversaria, 12mo. Lugd. Batav. 1682. Garden, A discourse on the modern theory of generation, Phil. Trans. 1691. Taury, De la generation et le nour. du foetus, Paris, 1700. Nigrisoli, Consid. intorno alia gene- razione de viventi, 4to. Ferrara, 1712. Valisnieri, Istoria della generaz. dell'uomo, Venet. 1721. A. Maitre Jean, Obs. sur la formation du poulet, 2mo. Paris, 1722. Leuwenhoech, in Phil. Trans, for 1693, 1699, 1701, 1711, and 1723; Opera om. 4to. Lugd. Batav. 1722. Brendel, De em- bryone in ovulo ante conceptionem, Gotting. 1740. D. de Super mile, Some reflexions on generation, Phil. Trans. 1740. Bianehi, De naturali, &c. generatione historia, Turin. 1741. ' Needham, A summary, &e. on generation, Phil. Trans. 1748. Buffon, Decouverte de la liqueur seminale, &c. Mem. de Paris} 1748. Haller, Ad Buffonii de generatione theoriam adnot. in Ej. Op. anat. minor, t. iii. Buffon, CEuvres de, t. i. and in Mem. de Paris, an 1753. Parsons, Philos. ob- se—'. on the analogy between the propagation of animals and that of vegetables, Lond. 1752. Haller, De quadrupedum utero, conceptu et foetn, in Ej. Op. anat. min. t. ii. Wolff, Theoria gene- rations, Halae, 1774. Spallanzani, Saggio d'osser- vazioni microscopiche concernenti il systema di generazione de Sig. Needham e Buffon, Modena, 1765. Memorie. sopra i muli di varii autori, Mo- dena, 1768. Sandifort, De ovo humano, in Ej. Obs. pathol. lib. iii. Senebier, Experiences pour servir a l'histoire de la generation, &c. de Spal- lanzani, &c. &c. Genev. 1785. Blumenbach, De nisu formativo Comm. Gotting. vol. viii. p. 41. Denrnan, Collection of engravings, Lond. 1787. Zroeifel, Uber die Entwickelungstheorie, ein brief an H. Senebier, Gotting. 1788. Mohrenheim, Nova conceptus atque generationis theoria, Kbnigsberg, 1789. Grasmeyer, De conceptione et fecundatioue, et Supplementa, Gotting. 1789. Speculations on the mode, &c. of impregnation, Edinb. 1789. Fontana, Lettera ad un amico sopra il systema degli soilluppi, Firenze, 1792; Transl. intoReil'sArchiv. Band. ii. Haighton, On the impregnation of ani- mals, Philos. Trans. 1797 ; Transl. in Reil's Archiv. Bd. 3d. Ludwig, De nisu formativo, Lips. 1801. Vicq d'Axyr, Anat. et phys. de l'ceuf, in CEuvres, t. iv. Pulley, On the proximate cause of impreg- nation, Lorrd. 1801. Oken,- Zeugung, Hamb. u. Wurzb. 1805. Prevost et Dumas, Nouv. theorie de generation, in Annates des Sciences Naturelles, 1825. The various systems of Physiology, but especially Treviranus, Burdach, vol. i., and Hal- ler's Elementa. ( Allen Thomson.) * See John Hunter's well known paper on the Free Martin in his Animal GSconomy, new ed. by Owen, 1838. GLAND, Gr. a^»; Lat. Glandula; Fr. Glande; Germ. Druse. An organ whose office is to separate from the blood a peculiar substance, almost invariably fluid ; constantly provided with an excretory duct ; formed of a process of the mucous mem- brane or of the skin, disposed either in the form of a sac or of a ramified canal ; which sac or canal in all cases is closed by a blind extremity ; and which, although amply supplied with blood, is never directly continuous with the bloodves- sels.* It is absolutely necessary to give this definite explanation of the meaning which is attached to the word gland in the present article, inasmuch as there is no term in anatomy that has been more vaguely, and as it appears to me more incorrectly employed. It is not necessary to point out the absurdity of applying this word to certain parts of the brain, or to the masses of fat contained in the joints, which were called by the older anato- mists glands ; in these instances the fallacy is immediately apparent; but there are other errors which, although less striking, are, I con- ceive, no less injurious in their effects. Thus in the glandular system many continental au- thorities include not only the liver, kidneys, salivary glands, and other organs, which are universally acknowledged to belong to this class ; but likewise the lymphatic glands, the thyroid, the thymus, the spleen, the supra- renal capsules, and the ovaries.f It is con- * The only real exception to this law is the testicle of fishes, in which no excretory duct seems to exist. t Bichat, after condemning the application of the term to the thyroid, the pineal gland, the lymphatic glands, &c. states, " we ought only to call those glands, which pour out by one or several ducts, a fluid which these bodies separate from the blood they receive by their vessels." Anat. Gen. torn. ii. p. 598. Meckel, on the contrary, objects to the opinion that an excretory duct is essential to a gland. Ac- cording to his definition the glandular system com- prises, 1. the mucous glands ; 2. the sebaceous glands ; 3. the liver, the salivary glands, the pan- creas, the lachrymal glands, the tonsils, testes, the ovaries, the prostate, Cowper's glands, the kidneys ; 4. the lymphatic glands, the thyroid, the mammary glands, thymus, spleen, supra-renal capsules. Man. d'Anat. torn. i. p. 511. It is surprising that so admirable a physiologist as Meckel should adopt this opinion. Professor Miiller has also a classification, which seems to me objectionable ; for he has admitted among the glands the spleen, thyroid, lymphatic glands, &c. It must not, however, be supposed from this arrangement that this profound anatomist considers these particular bodies as real glands. His classification is as follows. (Handbuch der Physiol, des Menschen, Coblenz, 1.834, p. 418.) « f A. Ganglia sanguineo- vasculvsa, the o I spleen in the digestive organs — the su- |3 % pra-renal capsules in the genital and 1 uro-poietic viscera — the thymus and J§ ^ \ thyroid in the respiratory apparatus — ■ § « J glandula choroidals in the eye — the m placenta in the fcetus. f B. G. lymphatico-vasculosa, the lym- M phatic and mesenteric glands. 5 * o 3 f f-1 .g * "° > Liver, salivary glands, testis, &c. w .2 ts 2 J 60 GLAND. 481 tended by these writers that the last named bodies elaborate from the blood certain fluids, and that as far as the real function of a gland is concerned, it matters not whether the secreted fluid escapes by a proper excretory duct, or is taken up by the lymphatic vessels; it is, in- deed, supposed by Haase that these bodies, like the true glands, possess excretory ducts, but this opinion has received little support. This method of viewing the subject appears to be very injudicious ; because it is based on the assumption that certain organs secrete fluids from the blood, but of which secretion we have no evidence ; and further, because organs are classed together, between which there is no similarity either of structure or of function. In establishing a well-founded distinction between parts which, in their general form and outward appearance, bear a resemblance to each other, it is proper to seek for some lead- ing and obvious character, concerning which there can be no dispute. In applying this rule to the presenUcase, we shall find that the spe- cial distinction of a true gland, as contrasted with those organs with which it has been assi- milated, is the possession of an excretory canal or duct ; and taking this as the essential cha- racteristic, there is no difficulty in perceiving that the glandular system in the human body ought to be restricted to the following parts: — Mucous glands, comprising, a, simple mu- cous glands or follicles, dispersed over the whole extent of the various mucous surfaces, either insulated or collected together, as the glandulae Peyeri seu aggregatae. b, Compound mucous glands, (g. agglutinate,) formed of the preceding, collected into masses, and slightly modified in their structure, comprising the molar, labial, palatine, and buccal glands, the lachrymal caruncle, tonsils, Cowper's glands, prostate, and seminal vesicles, c, Sebaceous glands, consisting of those of the skin, the ceruminous glands, the Meibomian glands, d, Conglomerate glands, (g. conglomerate ;) these, which are the most complex of the glan- dular organs, consisting of the salivary glands and pancreas, the mammary glands, the testicle, the kidney, and the liver. These glands may be classed according to their functions in the economy as follows: — I. P'or lubrication and protection ; a. mu- cous glands in all parts of the body ; b. seba- ceous glands ; c. lachrymal gland ; d. lachry- mal caruncle. II. Connected with digestion ; a. salivary gland ; b. pancreas ; c. liver. III. Connected with generation ; a. testis ; b. prostate ; c. seminal vesicles ; d. Cowper's glands; e. mammary gland. IV. For excretion ; a. kidney ; b. liver. By extending the principle that all glands are in reality nothing but processes of the mucous mem- brane ending in cul-de-sac, the lungs have, by some writers, been included amongst the glandular organs, the trachea, it is said, performing the office of an excretory duct. It is certain, as we shall subsequently show, that the lungs present, both in their formation and functions, a close approxima- tion to the true glands. VOL. II, The particular description of the above organs and the modifications of the general glandular structure they present, will be found in the articles Kidney, Lachrymal appara- tus, Mamma, &c. Situation. — The principal glands are placed in the head and abdomen ; in the extremities, with the exception of those of the skin, they are totally absent. In general they are pro- tected from external injury by being lodged deeply in the cavities of the body ; but to this rule there are several important exceptions, as the mammae, testes, parotid glands, &c. Organization. — In the whole range of Ana- tomy, whether Human or Comparative, there are probably no organs which, on account of the complexity of their structure, the number and variety of forms which they present, and the importance of their functions in the animal kingdom, are more interesting than the glands, or the structure of which, until within a very recent period, was more imperfectly understood. Even at the present time the prevailing ideas respecting the essential characters of the glan- dular organization are in general so vague and indefinite, and but too often positively errone- ous, that I feel myself called upon to enter more fully into the investigation of this subject, than would otherwise be necessary. Much of this uncertainty has arisen from the fact that, whilst the views of the immortal Malpighi, founded as they are on truly philosophic grounds, have never attracted that investigation to which they are so justly entitled, the theore- tical opinions of Ruysch, being received with all the eclat inspired by his unrivalled skill in vascular injections, have been generally adopted. It is true that, on many minor points, Malpighi was in error; and that the vagueness of his descriptions, and his infelicitous comparison of the ultimate divisions of the glands with clus- ters of grapes or acini,* greatly assisted in pre- venting his opinions being generally admitted or even comprehended. But those distin- guished anatomists who have, by their recent inquiries, at length decided the long-disputed theories of Malpighi and Ruysch, have proved that in all essential points the conclusions of the former great authority are founded in truth. Minute structure. — The investigation into the structure of the glands, when conducted in accordance with the enlightened principles of philosophical anatomy, shows that the laws which regulate their formation are simple and definite ; and that, although Nature has dis- played here, as in all her other works, immense fertility in modifying the forms and characters of the several glands, so as to render them effi- cient to the performance of their varied offices, yet in no single instance is there a departure from that structure, which constitutes the type of the whole glandular system. The unifor- * This term, so much employed in descriptions of the glands, yet so indefinite in its acepptation, has caused such confusion and misconception, that it is most desirable to abolish it from the nomen- clature of Anatomy. In the descriptive part of the present article, I shall therefore scrupulously avoid employing this expression. 2 K 482 GLAND. mity which, with the aid of Comparative Ana- tomy, has been so satisfactorily demonstrated in the development of the nervous and osseous systems, is equally evinced in the glands ; for whatever diversities may be presented in their form and appearances — whatever varieties may be remarked in the internal disposition of their component parts, as in contrasting a simple follicle with a conglomerate gland, or the tubu- lar biliferous organs of insects with the appa- rently solid liver of the Mammalia; whether, in short, they appear solid, cellular, or tubular, every glandular organ is nothing else than a modification of a simple closed sac. This im- portant truth is distinctly announced by Meckel in the following passage. " The most simple mucous glands, which are only simple sacs, present the type of the glandular formation. If we picture to ourselves this sac as being pro- longed and ramified, and interlacing its branches between those of the bloodvessels, we shall at length arrive at the most compound gland, without there ever being a direct communica- tion between the bloodvessels and the excretory ducts." * We have here briefly but clearly ex- pressed the great principle, in obedience to which the various glands are developed ; but that which Meckel only figuratively expressed, has since been realized in all its bearings and intricate details, by the extensive and laborious researches of several distinguished anatomists, and especially by Professor Miiller of Berlin. As it would be in vain to attempt to demon- strate the essential characters of the glandular formation, and to prove the uniformity which pervades the whole system, by selecting, as has been generally done, the most intricate organs ; I propose, in the first place, to describe the most simple form of gland, and, seizing this as a clue, to trace its gradual development through- out the whole series of glandular organs, so as to convey a general, but, it is hoped, compre- hensive account of this interesting branch of anatomy. With this object in view, the simple follicles of the skin and mucous membrane may be ad- vantageously selected ; because by tracing the successive development of these bodies, the gradual transformation of a simple sac into a tube, a ramified canal, and even a conglome- rate gland, may be very distinctly demonstrated. In fishes, whose aquatic mode of life renders an abundant defensive secretion necessary, the cutaneous follicles are more developed than in other animals, and constitute tubes or canals, which being carefully examined are found to end in ccecal extremities. A similar formation is seen in the bulbus glandulosus of most birds, where the mucous crypts are prolonged into short tubuli (fig. 209) ; whilst in the Ostrich ( Struthio camelus ) the follicles present an ap- pearance of cells. (Fig. 209, b). In some Amphibia, Salamandra maculuta for example, the glands of the external integument being very much developed, it is seen that each of * Man. d'An. i. p. 515. Beclard has a similar comparison : " it is true that a gland, like a folli- cle, consists of a canal closed at the extremity." Anat. Gen. p. 424. Fig. 209. a. Conglomerate folli- cular gland, Struthio rhea ; c. same, Meleagris ; d. same, Anser ;* the upper drawing shows the cylin- drical follicles in a young falcon. Fig. 210. those bodies is com- posed of a small flask- shaped pouch of the skin, which at one ex- tremity becoming en- larged into a base, there terminates in a. blindsac ; whilst at the other end being con- tracted, it opens by a short neck on the ex- ternal surface. (See fig. 210*.) A micro- scopical view of the coecal canals in the simpler glands is ap- pended. (See$g.2ll.) Fig. 211. Flask-shaped cutaneous The simple sacs and follicle or gland magni- tuDes just described are Jied—\W.i yery often couected t0ge. ther, giviug rise to aggregate or compound folli- cles, the arrangement and degree of complexity of which are very various. In some instances these sacs unite so as to form a gland witha single orifice or excretory duct, of which the Meibo- mian glands of the eye-lids are an example ; or again, the aggregate follicles may themselves be joined together with various degrees of compli- cation, in the form of a cluster, from which several excretory ducts proceed, as in the cu- runcula lachrymalis, the labial, buccal, and other mucous glands of the mouth, the tonsils, &c. In all these instances there is nothing but an evolution of the original sac, so that in the same manner as this is formed from the mucous membrane or skin, are the tubes and canals prolonged from the third pouch, by which con- trivance the surface subservient to secretion is, within a given space, greatly increased. The conversion of a sac or tube into a granular mass is also in this manner rendered very apparent ; and thus it is easy to understand how a rami- fied canal may produce the apparently solid * Home, Lect. on Comp. An. ii. tab. 46. t Berres. GLAND. 433 granules (the so much talked of acini ) of the liver and other conglomerate glands. Such, then, are the more simple forms of the glandular organs ; and if we proceed to those which are more complex, no difficulty is expe- rienced in proving, by the aid of comparative and developmental anatomy, that the structure, although it becomes more and more developed, is in character essentially the same. The inquiries of the anatomist in this respect are greatly facilitated by the existence of an univer- sal law connected with the process of organiza- tion, in accordance with which it happens that, whenever any particular gland first appears in the animal series, it presents invariably the simplest form of the glandular structure, al- though this same gland may subsequently attain in the higher classes the most intricate formation. It is for this reason the salivary glands are so simple when they first appear in birds, the pancreas in fishes, and the liver in insects. Ample confirmation of this gradual transition from simple to compound, which is in fact only another instance of the great laws which regulate the formation of the whole animal creation, is afforded by following any of the more intricate glands through the several stages of their development. Thus, if the pancreas be examined in its rudimentary state, it will be perceived that, like the mucous follicle, it is composed either of a fluid sac or of a tube more or less complicated. In the class Cephalopoda, the individuals of which are so remarkable by the complexity of their internal organization, the pancreas consists either of a simple sac opening into the intestine near the gizzard, (see fig. 219, p, fig. 220,/, vol. i. p. 533), or of a sprfal canal, (fig. 221, /', p. 535,) the secerning sifrface being increased by a number of lamina3. In most fishes there are numerous fluid appen- dages placed near the pyloric extremity of the stomach, ( appendices pyloric^,) which are with propriety regarded as constituting a rudimen- tary pancreas, (fig. 212,) and which, in the in- Fig. 212. Fig. 213. stance of the Sturgeon and Swordfish are ag- gregated into a glandular mass.* (See fig. 46, vol. i. p. 1 15.) The liver is certainly the most intricate struc- ture of all the glandular organs when examined in the higher animals ; and yet, if we descend to the lower classes, which present, as it were, a natural analysis of the various parts of the animal machine, the texture becomes suffici- ently simple. One of the most simple forms of this organ is probably furnished in the lum- bricus terrestris ; at least I have seen in that animal, in a few instances, a beautiful appear- ance of coecal tubuli composing the yellowish substance which coats the intestine, and which is thought by some authorities to constitute the liver. In many insects, Crustacea and other Articulata, the biliferous organs consist of fluid sacs proceeding from the stomach or intestine, and often assuming the appearance of tubes, but always closed at their distal extremities. In some instances these tubuli are very simple, (see fig. 37, d, vol. i. p. Ill,) but in other cases they are more complicated, and present a ramified arrangement ; and in this manner the structure evidently approaches that of the most compound or conglomerate glands. The liver of the Lobster presents an excellent illustration of the ccecal tubuli which constitute the secre- ting structure of so many species of glands. By cutting out a por- tion of this organ, and slightly unravelling the tubes by moving the section in water, the canals ending in cul- de-sac are beautifully seen, and if slightly magnified, it is found that they closely re- semble the pyloric ap- pendages of fishes. The * Haller remarks that, in the Skate and Shark, the pancreas is similar to that of higher animals 2 K 2 484 GLAND. adjoining figure (Jig. 214) conveys a very accurate representation of this structure as it exists in the biliary organs of the astacus Jluviatilis, the digital tubuli (c) being depicted as they appear when partly unravelled. In another of the Crustaceans, pagurus stria- tum (Jig. 215), the same kind of structure is Fig. 215. observed, constituting a very complex liver. In the squilla mantis that organ is so remark- ably intricate that Cuvier supposed it formed an exception when compared with the other genera of the Crustacea, which, as we have seen in the instances above, possess biliary organs composed of blind tubes, by being ta- bulated and solid like a conglomerate gland* It has, however, been ascertained that the lobules are excavated in their whole extent, and communicate by openings with the intes- tine, which runs through their spongy mass, so that the secreting surface is wonderfully increased in extent f That the liver consists of a blind pouch, originating from the intestinal canal and be- coming more and more complicated, is further shown in many of the Mollusca, in which the excretory ducts are so large that they appear like branches of the intestine, and thus present a structure which is somewhat analogous to * Lemons d'An. Comp. t.4. p. 152. It is proper to observe that Cuvier, in thus alluding to a solid conglomerate gland, appears to have fallen into the common error respecting the nature of the minute granules, or acini as they are called. t M'uller de Gland. Secernent. Struct, p. 70, $5. those curious ccecal diverticula observed in certain of the Annelida, well seen in the aphrudita acuteata, and which are by some anatomists regarded as forming a rudimentary liver. The evolution of the liver in the embryo affords an additional proof of the disposition of the secreting surface or membrane in the interior of the compound glands. In one of the Gasteropods ( Limnaus stagnalis ) the liver is first produced as a pellucid sac from the intestine. In an amphibious animal (buj'o cumpanisonus ) a prolongation in the form of a sac is seen in the intestinal membrane, which constitutes the first appearance of the liver; as the development proceeds, the hepatic duct is formed, and becoming ramified, produces at length a number of branching tubes, which present a granulated form. The evolution of the liver in the green lizard (lacerta viridh ) is very similar, the organ first appearing under the form of a hollow sac proceeding from and communicating with the cavity of the intestine, and subsequently having branches of ramified tubes added.* If from the investigation of these more simple forms, which might be multiplied almost ud in- finitum, we proceed to the conglomerate glands of Mammalia, it will be observed that, al- though the component parts of these highly organized bodies are so closely packed together as to present a solid and granular appearance, yet by a careful inspection it may be satisfac- torily determined that the true secreting struc- ture consists of tubuli with ccecal ends. For this purpose the testicle may be advantageously selected : if this organ without any previous injection be divided, the section at first sight seems to consist of a great number of small roundish bodies or granules; but if, as occa- sionally happens, the tubes are distended with semen at the time of death, by a more cautious examination it is immediately apparent that these little bodies are composed of a very fine tube coiled up or convoluted. By injecting the tubuli seminiferi with mercury, the formation of the little grains is rendered more evident; but the most successful mode of displaying the whole internal formation of the testis is by filling the tubuli with a coloured size injec- tion.f 1 1 was remarked by Ferrein J that the kid- ney is a tubular organ, and the extensive re- searches of Miiller as well as those of Huschke have proved that the secreting or cortical part is made up of an immense number of serpen- tine tubes of an equal diameter throughout, ending in blind sacs, and becoming continuous with the straight canals placed in the cones of the organ. This structure is seen in Jig. 216, where a magnified view of the cortical ducts of Ferrein, the secerning apparatus, and the straight excre- tory tubes is given as the parts exist in the sciurus. This structure offers a close resem- blance to the tubuliform liver of some insects. * Miiller 1. c. tab. x. Jig. 13. t Sir A. Cooper on Testicle. % Mem. de l'Acad. Roy. des Sc. 1749, p. 489. GLAND. 485 (See the biliary organs of Meloloutha Vulgaris, Jig. 38, vol. i. p. 111.) In the liver of Mammalia and Man, both in the embryo and after birth, it is much more difficult to demonstrate the ultimate tubes with their coecal extremities; indeed the existence of such canals is ra- ther deduced from the ana- logy of the liver in the lower animals than from actual ob- servation. M idler states that the blind free extremities of the biliary ducts are visible on the surface of the liver with the microscope in the embryo of Mammalia; but that owing to their compact arrangement they are less dis- tinct than in birds, so that their internal connexions can- not be perceived.* In a few Mammalia, however, as the squirrel, ( sciurusvu/garis,) he observed with the microscope the blind cylindrical extremi- ties of the biliary ducts on the surface of the liver, pre- senting a branching and foliaceous appearance. ( Fig. 217.) The exact mode of termination of Fia. 217. Fig. 216. the biliary tubuli was still more distinctly seen in a portion of liver considerably magnified, taken from an embryo of the quail, ( 'Tetruo coturnix,) about one inch long (Jig. 2X8). From the published Fie. 218. account of Mr. Kiernan's valuable observations on the minute structure of the liver, it does not appear that the actual terminations of the biliary tubes in blind extremities were perceived, although that such is their disposition is rendered very probable from what was seen with the mi- croscope, and especially because it was found that much greater difficulty was experi- enced in injecting these tubes than the bloodvessels, on account, as it was sur- mised, of the bile contained within them having no exit.* Lastly, in tracing the minute texture of these complex glands of the Mam- malia, it is necessary to call the attention of the reader to a circumstance which of all others has been the most fertile source of error, so much so indeed as to have misled the great majority of anatomists. It is this : in many glands small rounded or berry-shaped corpuscles seem to be appended to the commencement of the secreting tubes, so that a deceptive ap- pearance is produced, as if cells or little bags were placed between the terminal bloodvessels and the small excretory ducts. This appearance of cells or even of solid rounded corpuscles is depen- dent on two causes : in some glands the se- creting canals are so coiled up that, as is seen in the human testis, when a section is made in the uninjected state an apparently granular tex- ture is presented, (Jig. 219;) but a second influential circumstance is that in many in- stances each of the secreting tubes swells out at its ccecal end into a slightly enlarged cul- de-sac ( pedunculated tubes), so that when they are viewed in an aggregate form, the semblance of roundish-shaped granules is seen, (fig. 220.) As these and all other varieties which are presented in the glandular formation are * L. c. p. 80, $21, 22. * Phil. Trans. 1833, p. 741. 486 GLAND. It is, however, very remarkable that whilst those glands which arise from the alimentary canal present an immense variety in the ar- rangement of their secreting texture, the essen- tial glands of the genito-urinary apparatus, the kidney and the testicle, have a most uniform structure, consisting of serpentine tubes of the same diameter throughout their whole extent. The details into which I have thought it re- quisite to enter prove that the true secreting structure consists in every gland of nothing else than a vascular membrane, on the surface of which the glandular fluid is poured out; and consequently that in those complex organs, as the liver or kidney, in which the vascular se- Fig. 220. Peripheral ramification of the parotid du -t, with some of the vesicular terminations, magnified — 110.* Fig. 219. considered in the several articles on the individual glands, it is only necessary to state in this place that what are called indifferently lo- bules, glandular grains, vesicles, acini, &c. are in every instance composed simply of the secreting canals variously disposed and arranged creting membrane is, for the sake of conveni- ence, disposed in the form of extensively rami- fied tubes, it is most important to recollect that the glandular fluid is poured not only into the ccecal extremity or commencement of each tube, as is the commonly received opinion, but ak>ng the whole extent of the tube. For the establishment of this fact, certainly the most important in the history of the glands, we are principally indebted to Professor Muller. Excretory duct. — Although the essential seat of the glandular function is now ascertained, some difficulty exists in determining the actual extent of the secreting surface in the various organs ; or in other words, at what precise point the mucous canals ceasing to secrete, become mere excretory passages.^ An attempt to decide this point is, however, necessary, because until this time the majority of anato- * Berres, 1. c. pt. 5, tab. ix. fig. 2. t I allude here of course to the peculiar secre- tions, as the bile, urine, milk, &c. and not to the secretion of mucus, which we know is poured out along the whole extent of the excretory ducts. mists have signified by the term excretory duct, not only the canals which simply bear away the secreted fluid, but likewise those tubes which constitute the true secreting apparatus, and which, it is evident, are at the same time both secreting and excreting canals, as they not only secrete, but likewise carry to the larger and non-secreting ducts the fluids poured out by their parietes. In the simple sacculi or follicles, it is evi- dent that the secreting structure is co-equal with the extent of the bag itself, so that the little orifice becomes the excretory duct; in the tonsils, prostate, &c. there are several such orifices or ducts. But at what point does secretion cease in the compound glands ? Mr. Kiernan states,* that in the liver the secreting portion of the organ is confined to what he calls the lobular biliary plexuses, or to those tubes which are placed within the lobules ; so that here the excretory apparatus is very com- plex, consisting of the interlobular tubes, those * Phil. Trans. 1833, p. 741. GLAND. 487 of Glisson's capsules, and, lastly, of those which quit the organ. The limitation thus established, and which I have no doubt is strictly correct, may be applied to all those glands, such as the salivary, mammary organs, &c, which, like the liver, possess distinct lobules. In the kidney the true secreting structure is probably restricted to the serpen- tine tubes contained in the cortical texture, (canales corticales, or ducts of Ferrein,) the straight canals (tub. Belliniani) constituting the cones, which bodies, in a minute injection of the bloodvessels, are nearly colourless, being merely for excretion.* The testis, with its appendix the epididymis, presents an in- tricate arrangement; it is probable, however, that the principal secreting part consists of the seminal tubes which form the lobules, and that the vasa recta and efferentia are merely ex- cretory in their office; in the upper part of the epididymis a second secreting structure is met with, constituting the coni vasculosi, whilst the lower part containing the convolutions of the vas deferens is of the excretory character. It is proper to observe that the process of secretion is incessantly going on ; but with the exceptions of the mucous, sebaceous, and a few other glands, the fluids produced are destined to be poured out only at stated in- tervals ; it is, therefore, evident that some con- trivance is required, by which the several secre- tions may be retained, till the moment arrives when it is necessary they should be discharged. The liver may be selected to illustrate this principle : one of the most essential functions of that organ being the decarbonization of venous blood, its constant action is no less indispensable, indeed considering the whole animal series, is even more indispensable than that of the lungs themselves ; and yet the pro- duct of that action, the bile, is only designed to be poured into the duodenum during the process of digestion. In order to obviate the irritation of the bowels that would result from the incessant discharge of the bile, and at the same time to economise that fluid, the gall- bladder is provided, which, receiving the se- creted fluid in the intervals of digestion, fulfils all the conditions required. The absence of the gall-bladder in several classes of animals can scarcely be admitted as being incompatible with this explanation ; for the majority of these instances of deficiency occur in non- ruminant vegetable feeders, in several genera of the Pachydermata and Rodentia for example, in which it is evident that as the process of digestion must occupy a considerable period, a prolonged flow of bile is requisite, and a special reservoir is less necessary ; in addition to * It is stated by Muller that all his researches induce him to conclude that the serpentine tubuli of the cortical part constitute the true secreting texture; an opinion which is corroborated by a very curious preparation contained in the museum of the Webb -Street School of Anatomy, in which a sac has been formed on the outer surface of the kidney, containing a number of small calculi, and having no connexion whatever either with the straight tubes or with the infundibula. which it is known that in some of these cases, as in the horse and elephant, the principal trunk of the biliary ducts is very large, and may in some degree supply the place of a gall- bladder* The urinary bladder is a provision rather of convenience than of necessity, enabling the animals that possess it to retain the urine as it flows from the ureters, until a considerable accumulation takes place. These are the only instances in the human body of a distinct re- servoir being provided ;f but every gland, by retaining its secretion in the excretory ducts, has a power of emitting the fluid, under certain circumstances, in larger quantities than usual, as in the case of the salivary and lachrymal glands; a similar accumulation must take place in the seminal tubes and prostatic ducts, and especially in the lactiferous tubes and their terminal sinuses. In animals the examples of distinct reservoirs are too numerous to be here enumerated. Structure of the secreting canals and excre- tory ducts. — It is now certain that all these tubes are composed essentially of a prolonga- tion of the mucous membrane. The former, according to Muller, consist only of a single coat, but it must be presumed that they pos- sess in addition a tunic, having, independently of elasticity, a power of contraction by whicli their contents are propelled often in a direction opposed to gravity, and in obedience to the application of a mechanical stimulus to the surface on which the ducts terminate. In the excretory ducts the internal membrane is sur- rounded by a fibrous structure, which is very apparent in some of the larger canals, and probably exists in all. The fibres of this coat are of a greyish white or brownish colour, and are often so fine and compact that they are distinguished with great difficulty. The real character of this structure is not known ; in appearance there is little or no resemblance to proper muscle; the action, however, of the excretory canal seems to require a contractile power; and Meckel states that he has dis- tinctly perceived circular fibres in the vas deferens, which tube is said to be distinctly muscular in the bull. Bloodvessels. — If it be recollected that the arteries carry to the glands the materials of their various secretions, and if the large quan- tity of fluid formed by those viscera be called to mind, we shall not be surprised to find that with a few exceptions, such as the lungs and the brain, there are no organs so abundantly supplied with arterial blood. This supply is in proportion to the activity of secretion, rather than to the size of the gland ; thus the kidneys, * Carus, Traite Elem. d'An. Comp. ii. p. 269. It may be proper to state that the Otter, according to Daubenton, possesses the above dilatation of the duct in conjunction with a gall-bladder. f Some anatomists conceive that the vesiculas seminales are merely receptacles of the semen ; but this opinion has been to a great extent aban- doned in England since the observations of Hunter. See the works of Hunter, edit, by Palmer, vol. iv. p. 20. Note, p. 26. 488 GLAND. furnishing about four pints of urine daily, receive, in proportion to their bulk, more blood than the pancreas, where the secerning process is less active. That this is the principle which regulates the supply of blood is also evidenced in the vessels of the mammas, which receive a more ample supply of blood during lactation than at other periods. The sanguiferous vessels, like the secreting canals, present many varieties in their dis- position in the several glands, the varieties of form in each class being, however, definite in their character, and doubtless having a re- ference to the different kinds of fluids which are required to be separated from the circu- lating blood. Those organs which are pro- vided with a distinct envelope, as the testicle, the kidney, and liver, usually possess but one artery, which enters at the same fissure as the excretory canal ; other glands, presenting a more distinctly lobulated texture and having no proper capsule, the tonsil, pancreas, and mam- ma for instance, receive an indefinite number of arteries, which enter irregularly on all parts of the surface ; lastly, in the most simple form, as the mucous crypts, the secreting vessels con- stitute a delicate plexus on the surface of the little bag. In all those instances where the gland is large enough to receive one or more arterial trunks, it is found that the vessel having entered begins to divide into smaller branches, which penetrate between the masses of the gland, and these becoming smaller and smaller at length furnish an intricate plexus, the branches of which, as in the case of the simple bag or follicle, ramify on the surface of the blind secreting canals. It is only necessary to observe with respect to the veins, that when compared with their arteries, they are smaller than elsewhere ; and also that in common with the veins of the splanchnic cavities, they are devoid of valves, so that in the kidney, liver, &c. they may be beautifully displayed by the aid of a suc- cessful injection, even to their ultimate rami- fications. Arrangement of the minute bloodvessels. — In considering the intimate texture of the glands, it is essential to state the manner in which the last divisions of the sanguiferous vessels are disposed. By the aid of minute injection these vessels may be demonstrated, though with difficulty, as far as their termina- tion ; and they may also be observed in a few instances during life and whilst carrying on the circulation. An opinion to which we shall subsequently recur has been entertained by many anatomists, that the little arteries are either directly con- tinuous with the excretory ducts, or, as we should rather call them, the secreting canals, or, at all events, that some kind of direct commu- nication exists between the terminal arteries and the secreting canals. The most cautious and apparently successful researches, however, do not corroborate this opinion, but, on the contrary, show that no direct communication of any kind exists. In the lungs, which organs are formed and developed in exact accordance with the glandular structure, the ultimate divi- sions of the pulmonary artery, after freely ramifying over the surface of the air-cells, are known to terminate by direct continuity in the radicles of the pulmonary veins. Now, that which is demonstrated in the lungs equally applies in the case of the glands. In the simple lacunas of the mucous membrane the arteries are disposed over the surface of the pouch, but they end in the returning veins without opening on the secreting surface. Miiller states that on examining with a suffi- cient power the larva of the triton palustris, he observed streams of blood, traversed by single globules, running between the elongated secreting canals of the liver, and, further, that the last arteries pass immediately by a reticu- late anastomosis into the small hepatic veins. This disposition is seen in the adjoining figure, which represents the circuit of the blood in the larva of the triton fifteen lines in length. Fig. 221. a, vena cava ; b, vena portarum ; c, minute cur- reuts of blood in the gall-bladder. ^ GLAND. 489 Miiller expressly says, that in no organ are the free extremities of the bloodvessels seen, but that the arteries always pass by a reticulate anastomosis into the veins ; that the blood cir- culates between the secreting canals of the liver, and at length on their surface, so as, as it were, to soak their coats with blood, but it does not pass into the canals themselves; or, in other words, that the sanguiferous vessels are not continuous with the biliary tubes.* The important investigations of Kiernan respecting the minute anatomy of the liver, have shewn that the vena portee having divided so as to constitute an intricate plexus in each lobule of the organ, and having ramified on the secreting canals, terminates in the hepatic vein.f In the section on the development further evidence is furnished in corroboration of these observations. In all these instances, then, it is proved that there is no continuity between the arteries and the secreting tubes; and as the smallest secreting canals are always considerably larger than the smallest bloodvessels, the proportion varying in different glands, it may be assumed that in the whole glandular system, the arteries, having divided to a great degree of minuteness, and having ramified freely on the surface of the secreting canals, terminate directly in the re- turning veins. , Although in former times such a disposition of the bloodvessels as that now described would have been regarded as incompatible with the process of secretion, yet since the interesting researches of Dutrochet on Endos- mose and Exosmose,J there is no difficulty in understanding that fluids may readily pass from the interior of the arteries into the se- creting canals without there being any direct communication between these two orders of tubes. Not only may this passage take place, but even it is rendered probable by the experi- ments of Magendie§ that the bibulous matter constituting the glandular texture, and present- ing, as we have found, so many varieties in its physical characters, may separate fluids, varying, according to the gland employed, from the diversified substances mechanically mixed toge- ther and suspended in the blood. Lymphatic vessels. — Notwithstanding these are readily traced in the larger glands, their disposition, and especially their origin, are not known ; a connexion, however, has been rather generally admitted in certain glands between • De Gland. Struct., p. 74, § 12. Phys. des Menscben, 1 Band, p. 441. t Phil. Tran. 1833, p. 745. Mr. Kiernan infers that the hepatic artery terminates, not as is usually supposed in the vena hepatica, but in the vena porta?. Miiller, however, thinks it is not probable that this is the true disposition, because the prepa- rations of Leiberkuhn show that the capillary branches of the venae hepaticae can be as readily injected from the hepatic artery as from the hepatic vein. Notwithstanding these objections, analogy would induce us to suppose that Mr. Kiernan is correct in his supposition. | Nouv. Recher. sur l'Endos. et l'Exosmose, 1828. § Lect. on the Physical Conditions of the Tissues, Lancet, 1834-35. their ducts and the lymphatics. In one instance Cruikshank filled the absorbents of the mamma from the lactiferous ducts ; and both Walter and Kiernan contend that the absorbents of the liver may be injected from the biliary ducts. Miiller, on the contrary, denies this commu- nication, and states that the lymphatics are much larger than the smallest secreting canals. He also contends as to the results of injections, that the arguments drawn from them have no greater weight than all others derived from the fortuitous passage by rupture of fluids from one into a different order of vessels. Nerves. — In proportion to their size the glands, like the other organs of the vegetative functions, receive very small nerves, which are, with some few exceptions, derived from the system of the great sympathetic. The nervous fibrils surround and accompany the branches of the arteries, till, in the interior of the gland, they become so minute that it appears impossi- ble to detect their exact termination. Miiller states that they never separate from the blood- vessels, and, consequently, that they do not supply the proper glandular substance. But in such a case as this the evidence afforded by microscopical inspection alone should be re- ceived with great reserve, especially when it is recollected that in opposition to the doubtful information thus acquired must be placed the unquestioned fact that the mind is capable of influencing the contraction of the secreting and excreting tubes, as is instanced in the flow of the saliva, of the tears, and of the semen under certain mental impulses. But perhaps a still more striking illustration of the control of the nervous system is afforded by the discharge of several glandular fluids resulting from impres- sions acting on comparatively remote but associated surfaces — the pouring forth of the saliva for example, in consequence of the con- tact of various substances with the tongue ; of the bile and pancreatic juice from the applica- tion of food to the surface of the duodenum ; of the semen from the stimulation of the glans penis. In all these and similar instances it must be presumed from analogy that the effect of the physical impression is conveyed through the only known media of conduction, the nerves.* The facts here adduced respecting the influence of the nerves merely relate to the contraction of the secreting and excreting canals ; how far the nervous energy is essential to the process of glandular secretion itself be- longs to another division of the subject. (See Secretion.) Interstitial cellular tissue. — A considerable portion of every gland is made up of the con- necting cellular membrane, which, as in all other organs, enters the interior, where it fills up all the minute fissures and angles that intervene between the tubes and lobules, and at length, penetrating between the most minute of the secreting canals, it constitutes a nidus for the lodgement of the constituent parts. The investing membrane is in many instances * I have in another place entered more fully upon this question : Obs. on the Struct, and Funct. of the Spinal Cord, p. 136, ct scq. 490 GLAND. simply formed by the condensation of the con- necting cellular tissue, but in the larger glands a proper fibrous capsule is provided, which adheres more or less intimately to the proper glandular texture. General conclusions respecting the minute structure of glands. 1. That throughout the whole range of the animal kingdom and in every species of gland there is one uniform type, from which the glandular formation in no instance deviates. 2. That every gland consists of a membrane derived either from the skin or mucous mem- brane. 3. That this membrane is disposed either in the form of a pouch or of a tube more or less ramified, and terminates in every instance, with- out an exception, in a blind extremity. 4. That the secreting canals are most diversi- fied in form, being simply sacculated, branch- ing, pennitifid, nail-shaped, or enlarged at the commencement, cellular, berry-shaped, serpen- tine. 5. That granules or acini in the hypothetical sense of writers do not in reality exist. 6. That whatever may be the variety of form it is always subordinate to the grand principle which the whole glandular system displays, — namely, that the largest possible extent of secreting surface is contained in the smallest possible space. 7. That there is no immediate connexion or continuity between the secreting canals and the sanguiferous vessels. Hypotheses respecting the minute structure of glands. — I was desirous in the first part of this article to convey to the reader a com- prehensive view of the glandular structure, unincumbered by any reference to the opinions of anatomists on this subject; but the hy- potheses of Malpighi and Kuysch have so long divided the world of science, that it is necessary to ascertain how far the doctrines advocated by those celebrated men are in accordance with the above-stated conclusions. In doing this, however, much difficulty is experienced, especially in considering the opinions of Malpighi, inasmuch as his com- parisons of the minute structure of the liver, of which organ he principally treated, are very vague and obscure, and being for the most part unaccompanied by illustrative plates, it is almost impossible in many of his descriptions to detect the meaning he wishes to convey. But, notwithstanding these obstacles, it is evident, on studying his account of the liver and kidney, that justice has not been done to his researches; for he not only corrected many of the then prevailing errors, but also ascertained several important points connected with this interesting branch of anatomy. Malpighi compares the minute lobules of the liver and other conglomerate glands to a bunch of grapes, these lobules being joined to the neighbouring lobules by intermediate vessels. His words are, ': for as an entire bunch of grapes is formed of small bunches by a communion and tying together of vessels, which small bunches are themselves formed into a mass by appended grapes (acini); so the whole liver is formed by lobules many times folded, and which are themselves formed of glandular globules."* It is thus observed that Malpighi describes in the liver larger and smaller lobules ; and it is to these latter that the celebrated but vague term of acini appears to be more particularly applied. He observes that the lobules are of various forms in different animals ; in fishes having the shape of a trefoil, in the cat six-sided, &c. The inter- lobular spaces are noticed as being distinct in fishes, but as obscure in the more perfect animals. With respect to the intimate structure of the small lobules, or acini, Malpighi conceived that each of them consisted of a hollow vesicle, receiving the secreted fluid from the small arteries and conveying it into one of the roots or branches of the hepatic duct ; or, in other words, that the structure of the acinus was the same as that of the simple mucous follicle. Owing, however, to the imperfect means then possessed of prosecuting such inquiries, it is certain that Malpighi did not detect the ultimate structure ; for more exact observations have proved that the last divisions of the secreting canals, although they constantly terminate in ccecal extremities, do not always end in follicles, but that they may consist of serpentine tubes, as in the kidney, or of pennatifid canals, &c. It also has been determined that what he regarded as the last divisions of the ducts, or acini, are themselves composed of smaller canals. But his observations on the develope- ment of the liver in the chick shew that he was acquainted with the essential facts con- nected with the structure of that organ, and with the mode of its formation ; for among other interesting remarks, he says that on the seventh day of incubation the liver of a yellow- ish or ashen colour presents granules of rather an oblong form, and "as it were blind pouches, appended to the hepatic duct."f This hypothesis, founded as it is on so large a body of evidence, was generally re- ceived ; but the discovery of the art of minute injection, which seemed to afford ocular de- monstration of the fallacy of Malpighi's theory, induced the majority of anatomists to adopt the ideas rather pompously announced by Ruysch. This celebrated anatomist, rejecting the hypothesis of Malpighi, contended]: that he had proved, by injection, that the arteries are directly continuous with the excretory ducts; or that the little ducts proceed from the minute arteries, like lesser from larger brandies ; and that each acinus consists prin- cipally of bloodvessels, but contains also an excretory duct.§ In considering the merits of these two hy- potheses, it becomes apparent that Ruysch supported his opinion by evidence of a most insufficient character ; for in investigating the * De Viscer. Struct, cap. iii. p. 18. t De Format. Pulli in Ovo, p. 20. j Opuscul. Anat. de Fabric. Gland. Opera omnia, t. iii. § hoc cit. p. 56, Jig. 2. GLAND. 491 roost complicated glands he relied solely on his vascular injections, to the exclusion of the evidence afforded by the much more satisfactory researches of comparative and developmental anatomy. If, as Professor Miiller has ob- served, Ruysch had carefully examined his injected organs with the microscope, he would have found that between the most delicate plexuses of the bloodvessels there is always an additional substance destitute of vessels ; although these organs, when seen by the naked eye, appear to be stained in every direction with the coloured injection.* But even ad- mitting what frequently happens from a too forcible injection, that the matter thrown into the arteries is found in the ducts, this does not prove that the small bloodvessels are con- tinuous with the excretory canals ; for after the sanguiferous vessels are tilled, they easily become ruptured, and so allow their contents to escape into the ducts. It may further be objected, that in all the glandular organs which have been carefully inspected the commence- ments of the excretory ducts are larger than the least arteries ;f indeed, Ruysch's own account of this imaginary continuity is very vague, and the plates designed to illustrate his theory, especially that of the kidney, are any thing but satisfactory. As Ruysch did not employ the microscope, it is impossible he could have seen that continuity which he so confidently described ; indeed, as Haller remarks,^ 'l 's difficult, or rather as we should say impossible, to demonstrate, with the aid of the most powerful lens, the connexion of the last arteries with the coats of the ducts. Not only did Ruysch adopt a most in- sufficient mode in prosecuting his inquiries, but he assumed as a fact what was in reality a mere hypothesis, that secretion can only take place from the open mouths or orifices of the secerning arteries. The only point, therefore, which he discussed was, whether the passage of the arteries into the excretory ducts takes place gradually and insensibly, or suddenly and by the intervention of a follicle; for it never occurred to the anatomists of those times, or even to Haller and his contemporaries, that canals closed at their end by cul-de-sac, and without open arterial mouths, could secrete. § * Loc. cit. p. 8, § 4. t Diameter of secreting canals. Line Parotid gland . . . 0 0099 (Weber). Kidney .... 0-0166 (Meckel). Ditto 0-0180 (Weber). Testis .... 0 0564 (Miiller). Ditto 0 0648 (Lauth). Liver (in rabbits) . . 0 0140 ( Miiller). Diameter of capillary bloodvessels. Line Line Parotid . . 0 0030 to 0-0039 (Weber). Kidney . . 0 0044 to 0 0069 (Miiller). Testis . . . 0 0030 to 0 0035 (Weber). Burdach Physiol. Fiinfter Band. p. 38. For measurements in otber glands, see Miiller De Gland. Struct, p. 112; Valentin Handb. der En- twickelungs-geschichte, p. 535 et seq. } El. Phy. t. ii. p. 378. $ The existence of open mouths in the arteries of the serous membranes, where they are generally But the true opinions of Malpighi did not refer to the exact mode of termination pos- sessed by the arteries; nor did he imagine that any particular machine or follicle was interposed between the arteries and the ducts : his observations were rather directed to the more important circumstances relative to the disposition, formation, and extent of the true secreting canals. In concluding these remarks on the hypo- thesis of Malpighi, it is due to the character of that illustrious cultivator of anatomical sci- ence to state that his views are highly phi- losophic, and in a general manner correct — that they are supported by numerous obser- vations made on the glands of the lower ani- mals, as well as on the development of the liver during incubation — and that he had thus the sagacity to adopt the mode, which expe- rience has shown is alone capable of resolving this difficult question. It would be superfluous to enter into a de- tailed account of the opinions advanced by later anatomists, as they are for the most part simply modifications of the hypothesis either of Malpighi or of Ruysch. A few general observations will therefore suffice. Ferrein has the merit of being the first wri- ter who pointed out in a more distinct manner than had been done by Malpighi, the great importance of what are erroneously called the excretory ducts, but which constitute, as we have already shown, the true secerning struc- ture, lie remarks * that the cortical part of the kidney is composed of a collection of white cylindrical tubes, variously folded on them- selves (canales corticales, or ducts of Ferrein,) and he thought he had seen the same tubes in the liver. The serpentine cortical canals have been seen in birds by Galvani, to be filled with cretaceous urine after the ligature of the ureter. Although the researches of Ferrein are very important, yet they want that support from comparative anatomy, by which means alone they could have been made subservient to esta- blish any general principles. To Rolando belongs the honour of having demonstrated the mode in which the glands are developed from the alimentary canal. By carefully conducted observations on the in- cubated egg, he discovered that each of these organs in the first instance consists of an ele- vation or tubercle of the intestine, which sub- sequently becomes hollowed and forms a canal directly continuous with that of the intestine. He also distinctly announced what has since been demonstrated in all its details, that the lungs are formed, like the glands, by a pushing out of the upper end of the intestinal tube ; and he further describes the mode in which the bronchi and their subdivisions are deve- loped. The error of those writers who contend called exhalants, has never been proved ; on the contrary, on examining, with a powerful micro- scope, the circulation of the peritoneum in rabbits, 1 have repeatedly observed that the small arteries, after ramifying in a very complicated manner, become distinctly continuous with the little veins. * Mem. de l'Acad. Roy. des Sc. 1749, p. 492. 492 with Ruysch that the bloodvessels and the secreting canals are continuous with each other, is clearly shown ; in short, Rolando was the first modern anatomist, who, following in the footsteps of Malpighi, pointed out the manner in which the inquiry ought to be prosecuted, and thus laid the foundation of those laborious and interesting researches for which science is principally indebted to the German anatomists, and by which, within the last few years, the subject of the glandular organization has been so strikingly elucidated.* Development. — The investigations of Har- vey, Malpighi, Rolando, Weber, Meckel, Bar, Valentin, Rathke, Miiller, and many other anatomists, have very satisfactorily determined the manner in which the glands are in general developed. It is, however, necessary to pre- mise that these observations principally relate to those glandular organs which are appended to the alimentary canal, especially the salivary glands, the pancreas, and liver ; for as regards the development of those glands that are subordinate to the secretion of urine and to generation, comprising essentially the kidney and the testis, much uncertainty still prevails, although it is rather generally believed that the corpora Wolffiana, or false kidneys, are in some way or other connected with their primary for- mation.f From the researches that have been made with so much care, we learn that, although there are many modifications of the formative process in the different classes of the glandular organs, there are yet certain fixed laws in obedience to which they are produced. As the development of the individual glands is, how- ever, considered in the several articles on those organs, it is only requisite to describe in this place in a general manner, and without no- ticing the modifications of the general rule, the process of formation. In prosecuting this inquiry two different objects present themselves for examination, — the primitive substance in which the gland is developed, and the internal component parts, consisting essentially of the secreting tubuli and the bloodvessels. 1. Every gland is formed from a portion of the primary plastic and amorphous mass ( blastoderma ) of which the body of the embryo consists. 2. This mass is at first gelatinous, extremely delicate and diaphanous ; it subsequently be- * Journ. Comp. des Sc. Med. xvi, p. 54, p. 57. P. b'3. The honour of discovering the mode in which the glands appended to the alimentary pas- sage are formed by pushings-out of that tube has been by Burdach improperly attributed to Rathke. t It would be inconsistent with the perfection of the formative process to conceive that either the kidney or the testis requires the aid of any other glandular organ for their development ; besides which it may be mentioned that there is no actual connexion between the above glands and the corpora Wolffiana. Rathke observes. " Although they (corpora Wolffiana) are not organically connected with the kidneys and genital organs, they appear to be, in an early period of the life of the embryo, the precursor or representative of the kidney." Burdach, II. Band. p. 646. GLAND. comes thicker and less transparent. In the beginning it is solid, and in the case of those glands which are appended to the alimentary canal, — that is to say, the salivary glands, the liver, and the pancreas, (and the same laws are observed in the formation of the lungs,*) it appears as a projection on the mucous mem- brane. (Fig. 222, A.) a B ■PiL a 6 D A plan designed to show the first origin of the glands. a, b, alimentary canal ; g, gland. (The letters have the same signification in A, B, C, D.) 3. In a short time this rounded mass begins to project on its external surface, and thus forms a number of lobes, or, as it were, little islands, which, by the continuation of the same process, become more and more numerous and smaller in size; and thus, according to the cha- racter of the gland examined, are at length formed all the minute lobes of which it con- sists. (Fig. 222, B.) 4. Simultaneously with this development of the outer surface of the plastic mass, but quite independently of it, a metamorphosis is going on within, by which the internal canals, which subsequently become the secreting tubes, are formed. In the first instance a hollow or cavity is noticed communicating with the tube of the intestine, and which subsequently be- comes the principal or excretory duct. When it first appears it is a simple sac, (fig. 222, C,) but in proportion as the projections or lobes are formed on the external surface, lateral branches are added to the principal duct ; and these again become more and more ramified, till an indefinite number of tubes are formed. (Fig. Ill, D.) * Rathke, in Burdach's Phy. II. Band. p. 580, edit. 1837. Valentin, 1. c. p. 501 et seq. GLAND. 493 This development of coecal tubuli is seen in the liver of Limrueus stagnulis in the em- bryo state, (fig. 223). In the embryo of Lacerta vi- ridis, (fig. 224,) the rudimen- tary liver with its blind se- creting canals (e) are observed; the elongated heart (a) fur- Fig. 224. nishing the aorta (6) dividing into its right and left trunks, together with the principal venous trunk (c ), are represented ; d is the intestine, / the rudiment of the corpora Wolffiana, and g g the rudiments of the upper and lower extremities. One of the most remarkable differences ob- served in the development of the several glands relates to the proportion between the mass of the primary plastic substance, and the extent and number of the contained tubes ; thus, in the evolution of the liver there is seen a thick layer of the primitive matter ; whilst, on the contrary, the parotid gland in the embryo of a calf two inches seven lines long, consists of a tube visible to the naked eye, and not at all covered by parenchyma. 5. The mode in which the secondary tubes are developed has been observed with great care; and it is distinctly established that they do not proceed as mere elongations of the pri- mary cavity, but are formed in an indepen- dent manner. One of the latest writers on the development of the body, Valentin * has given a very exact account of the process in all the glands. He states that in the neighbour- hood of the chief duct or of a branch of it, small oblong accumulations of the plastic mass are formed, which become hollowed in the interior, and these hollows, at first inde- pendent of the principal cavity, subsequently communicate with it. It is also observed by Muller that in the kidney of Batrachian Am- phibia, the secreting tubes first appear as * Loc. cit. p. 521, et alibi. vesicles which are formed before the ureter, and therefore independently of the principal duct.* As the tubes become more developed, the plastic substance around them, by acquiring greater firmness, constitutes their walls, and thus determines their exact form and limits. It is necessary to state that in every instance without an exception, the newly-formed canals end in coecal extremities, which are often rather swollen, presenting a pedunculated ap- pearance. 6. In proportion as the canals become formed in the substance of the plastic mass, this latter gradually diminishes in quantity, till ultimately, when all the tubuli are formed, it is so much reduced that it merely fills up the interlobular fissures, and is in fact converted into the interstitial cellular tissue. 7. At the same period of time that the tubes are thus being formed, the bloodvessels are being developed ; and, as Muller and Valentin remark, a very close parallel is presented in the generation of these the essential parts of the gland. As in the case of the tubes, there are at first little masses, or islands, of the plastic substance, which subsequently join together, and their interior becoming liquified, a num- ber of little channels are formed containing a circulating fluid, and which channels, by the subsequent consolidation of their walls, are at length formed into perfect bloodvessels. Like the tubes these vessels are at first independent ; they afterwards open into larger trunks and ultimately into the heart. It is proper to remark that, although there is such a corres- pondence in the process of development in each instance, the bloodvessels are formed quite independently of the canals ; that they occupy a different part of the plastic mass; and that they never present that continuity which ought at this epoch to have been very apparent, if the theory of Ruysch had been founded in truth. 8. The several glands are not developed equally early, some having their organization much more advanced than others; thus at the time when the pancreas is so far formed as to contain an immense number of canals, the parotid presents only a single duct or a few ramifications.f The principle which regulates the relative degree of development has evi- dently reference to the importance of the organ during the foetal life ; and in this respect the liver is most remarkable, for that body being, as I conceive, the true decarbonising organ in the animal kingdom, and therefore its func- tions being doubtless necessary in the foetus, very quickly acquires a high degree of organi- zation, so much so that, as we learn from all observations, it very speedily fills the greatest part of the abdomen. J * De Gland. Struct, p. 87. t Rathke in Burdach's Phy. II. Band. p. 576. Valentin, 1. c. p. 225. $ In the embryo of a sheep five lines in length, Valentin has found the liver filling half of the abdominal cavity; and in the embryo eight lines long, that organ constitutes three-fourths of the bulk of the viscera contained in the peritoneum: 494 GLOSSO-PIIARYNGEAL NERVE. Lastly, The laws in obedience to which the glands are developed, are as universal as to their existence in the animal kingdom, as those which regulate the formation of the nervous, osseous, and vascular systems ; and thus it may be noticed that the complex glands of man and the mammalia, such as the parotid, the pancreas, and the liver, pass, in the various epochs of their development, through those forms, which in the lower animals, and espe- cially in the invertebrated tribes, constitute the permanent structure. It may also be stated, that when any particular gland first appears in the animal series, it presents the most simple structure, although the same gland in the higher classes acquires the highest degree of complexity. Thus, the liver in insects is tu- bular, and in many of the amphibia excavated into large cells ; the pancreas in fishes consists of separate tubuli; the salivary glands of birds are extremely simple ; so also are the mam- mary glands in the Cetacea, and the prostate glands in many of the Mammalia. Bibliography. — Malpighi, De vise, struct, cap. iii. p. 18, et alibi ; De format. Pulli in ovo, p. 20. Ruysch, Opera omnia, torn. iii. Holler, Elem. Phys. ii. Ferrein, Mem. de l'Acad. Roy. des Sc. 1749. Cuvier, Lei;ons d'Anat. Comp. torn, iv. Rolando, Journ. Comp. des Sc. Med. torn. xvi. The Treatises of Bichat, Meckel, and Beclard on Gen. Anat. Miiller, De gland, secernent, struct, penit. Handb. der Phy. I. Band. p. 418. Trans, of ditto by Baly, vol. i. p. 441. Burdach, Phy. II. Band. edit. 1837, pp. 258, 264, 287, 376, 375, et alibi. This volume contains a large collection of the most important facts relative to the deve- lopment of the several organs, V. Band. p. 36 et seq. Kiernan in Phil. Trans. 1833. Valentin, Handb. der Entwickelungs -geschichte, pp. 495, 514, 521, 533. Boer, De ovo Mammal., and in Burdach's Phy. Cants, Anat. Comp. par Jour- dan, torn. ii. Grant's Lect. on Comp. Anat. in Lancet, 1833-34. Blumenbach, Man. of Comp. Anat. by Coulson. Berres, Die Mikroskopischen Gebilde des Menschlichen Kbrpers. ( R. D. Grainger.) GLOSSO - PHARYNGEAL NERVE (nervus glosso-pharyngeus ; part of the sixth pair of Galen and the older anatomists ; part of the eighth pair of Willis ; the ninth pair of Soemmerring and some of the modern anato- mists). The glosso-pharyngeal, par vagum, and spinal accessory nerves were long considered as forming a single nerve. Willis first clearly pointed out the origin and course of the spinal accessory, separated it from the par vagum, and termed it the nervus accessorius. The glosso- pharyngeal appears to have been generally de- scribed at the time of Willis as a branch of the par vagum. The term glosso-pharyngeal was not applied to it until the time of Huber* Previous to the time of Willis, however, some anatomists, more particularly Fallopius,t Eu- (1. c. p. 517.) Similar observations have been made in other animals and in the human embryo by Meckel. * Epistola Anat. de Nervo Intercostali, De Nervis Octavi et Noni Paris, &c. p. 17. Goet. 1744. f Opera quae adhuc existant omnia, p. 455. Francof. stachius,* Bauhinus,f had shown that this nerve was really not a mere branch of the par vagum. The same thing was stated, more or less strongly, by many subsequent anatomists, more particu- larly by Winslow,]; Haller,§ and Vicq D'Azyr.|| Soemmerringlf and Andersch** were, how- ever, the first who fairly separated the glosso- pharyngeal from the par vagum, and ranked it as a distinct nerve. The glosso-pharyngei form the ninth pair of Soemmerring's classification of the encephalic nerves, and were termed the eighth pair by Andersch. There can be no doubt that if we adopt the numerical method of naming these nerves, the glosso-pharyngei properly form the ninth pair. To avoid, how- ever, all the misunderstanding which is apt to arise from the use of numerical names when applied to these nerves, the best designa- tion for the nerve at present under our conside- ration is the glosso-pharyngeal, derived from its being principally distributed upon the tongue and the pharynx. I need scarcely state that, under the term eighth pair, as it is most gene- rally used in modern writings, is included the glosso-pharyngeal, par vagum, and spinal ac- cessory nerves, ff Origin. — The glosso-pharyngeal nerve arises by from two to six filaments from the restiform body of the medulla oblongata, closely upon the groove which separates the restiform from the olivary body. At its origin it is placed im- mediately above and in the same line with the par vagum nerve, and between it and the portio dura of the seventh pair. lis lower margin is generally separated from the upper margin of the par vagum by a few small bloodvessels. From its origin it first proceeds outwards along with the par vagum and spinal accessory to reach the foramen lacerum posterius. Through the anterior and inner part of this foramen it escapes from the interior of the cra- nium, and is enclosed in a strong and separate sheath furnished by the dura mater.JJ In its passage through the foramen lacerum it is placed anterior to the par vagum and spinal accessory and the commencement of the inter- * Explicatio Tabularum Anatomicarum Eusta- chii, tab. xviii. Bat. 1744. t Theatrum Anatomicum, cap. xxiii. p. 659. Francof. 1605. \ Exposition Anatomiqne de la Structure du Corps Humain, torn. iii. p. 106. Amstel. 1743. $ Elementa Physiol, torn. iv. cap. xxix. p. 231-2. Laus. 1562. || Traite d'Anatomie et de Physiologie avec des planches coloriees, etc. No. iii. p. 56. Paris, 1786. If De Basi Encephali et Originibus Nervorum, &c. in torn. ii. p. 97. Ludwig. Script. Neurol. Sel. Min. 1792. ** Fragmentum Descrip. Nerv. Cardiac, in torn, ii. Ludwig. Sc. Neur. Sel. Min. p. 113. ft Those who may wish to examine at greater length the literature of this nerve may consult Soemmerring Oper. Cit. p. 97, and more particu- larly Kilian Anatomische Untersuchungen iiber dasneunte Himnervenpaar oderden Nervus Glosso- pharyngeus, p. 1-62. Pesth, 1822. |t According to Morgagni (Adversar. Anat. vi. Animad. xii.) and Wrisberg (De Nervis Pharyn- gis, in torn. iii. p. 52. Ludwig. Script. Neur. Sel. Min.) this septum separating the glosso-pharyn- geal from the par vagum is sometimes osseous. GLOSSO-PHARYNGEAL NERVE. 495 nal jugular vein, which lie in the order here enumerated. As the nerve issues from the lower part of the foramen lacerum it forms a small rounded chord, close to, but still quite separate from the par vagum, and is situated between the internal jugular vein and internal carotid artery. It now leaves the trunk of the par vagum, proceeds downwards, inwards, and forwards, passing in front of the internal carotid artery and behind the styloid muscles, and joins itself to the stylo-pharyngeus muscle. It runs at first along the lower margin of this muscle, and rests on the superior constrictor of the pharynx which separates it from the tonsil ; it then mounts on the anterior surface of the stylo-pharyngeus muscle, and passes be- tween it and the stylo-glossus to reach the base of the tongue, upon which it is ultimately dis- tributed. Occasionally, instead of turning over the lower edge of the stylo-pharyngeus, it per- forates this muscle. In following the course here described, it forms a slight curve, the con- vexity of which looks downwards, and it sends off several branches, which are principally dis- tributed to the pharynx and isthmus of the fauces. These branches vary very considerably in size and in number in different subjects, but the general distribution of the nerve is in all cases nearly the same. When the branches are few in number, this is compensated for by their increased bulk, and when they are more numerous they are of diminished size. This nerve generally anastomoses with the par vagum within the cranium by a pretty distinct branch.* As the nerve lies within the foramen lacerum it presents two swellings or ganglia upon it, and gives off some small branches. The superior of these two ganglia is considerably smaller than the inferior, and has been termed die ganglion ju- gidareby J. Muller, (fig. 225). It is described by Mullerf as generally present, though small, placed upon the posterior or external side of the nerve, and situated at the cranial end of the foramen lacerum. It can only be distinctly seen after the dura mater has been removed, and the upper margin of the opening chiseled away. I have repeatedly observed this gan- glion jugulare in the human subject. In one case which I lately dissected, where it was comparatively large, very distinct, and pre- sented undoubtedly all the appearance of a true ganglion, it appeared to me, after careful examination, that this swelling does not include the whole of the nerve, but is confined, as Muller states, to the posterior filaments. These posterior filaments do not seem to differ other- wise in appearance from the anterior. This ganglion was first pointed out by Ehrenritter, and mentioned by Soemmerring on his autho- rity.J Very little attention seems to have been paid to this ganglion, so that when it was lately re-described by Muller,§ it was supposed that * Op. cit. p. 114. t Handbuch der Physiologie des Menschen. Erster Band, p. 589. t Arnold in Tiedemann's Zeitschrift fur Physio- logie, vol. ii. p. 175, and J. Muller, in his Archiv. fur Anat. und Phys. &c. 1837. No. ii. p. 275. j> In Vergl. Jahresbericht Von 1833, Archiv. fur Anatomie und Physiol. 1834, p. 11. its existence in the human subject had been hitherto unknown.* Mayer, of Bonn, had, previous to this (1833), described two small swellings upon the root of the glosso-pharyn- geal in the ox, but he failed to detect any similar ganglion in the human species. No nervous filaments either leave or join that part of the trunk of the nerve upon which the gan- glion jugulare is placed. The inferior ganglion (ganglion petrosum, ganglion of Andersch) is considerably larger than the superior, is of an oblong shape, and includes all the filaments of the nerve. It is described by Anderschf as about five lines in length, and commencing about four lines below the place where the nerve perforates the dura mater. No doubt, if we include all that portion of the trunk of the nerve which appears to be somewhat increased in size, it may sometimes measure five lines, but the true gangliform enlargement is consi- derably less. As WutzerJ remarks, it is rarely found to exceed two lines in length. This gan- Natural size. Magn ified about four times. glion lies in a distinct depression in the pe- trous portion of the temporal bone, which Andersch terms receptaculum ganglioli petrosi. Some branches both proceed from and join that portion of the nerve occupied by this gan- glion petrosum. The most important of these is a small branch which proceeds from the ganglion into the tympanum (ramus tympani- cus nervi glosso-pharyngei ; nerve of Jacobson). The course and distribution of this branch were partly known to Schmiedal, Andersch, Ehren- ritter, and Comparetti,|| but were more fully * I find that Wutzer, in his Monograph " De Corporis Humani Gangliorum Fabrica atque Usu," p. 92, after describing the inferior ganglion of the glosso-pharyngeal, says, * secundarium ganglion quod nonnumquam adesse Ehrenritter contendit mini non sub oculos cecidit." t If Andersch is not to be considered the disco- verer of this ganglion, it cannot be denied that he first gave a full and clear description of it. (Op. cit. p. 115.) Kilian (Op. cit. p. 30 and 75) con- tends that the existence of this ganglion was known to Winslow. In evidence of this he quotes the following sentence from his Exposit. Anatom. torn, iii. " les deux portions (nervus glosso-pharyngeus et nervus vagus) sont edroitement collees ensemble et communiquent de part et d'autre par des filamens qui grossissent un peu la petite portion (glosso- pharyngeal.)" | Op. cit. p. 91. § [This figure is taken from a dissection by Mr. Walker in the Webb-street School of Anatomy. The Editor is indebted for it to the kindness of his friend Mr. Grainger.] || Vide Muller's Archiv. fur Anat. und Physiol. &c. No. ii. 1837. p. 281. 496 GLOSSO-PHARYNGEAL NERVE. described by Jacobson* Tlie nervus tympa- nicus enters a canal in the petrous portion of the temporal bone, and there anastomoses with the Vidian and the carotid plexus of the sym- pathetic. The orifice of this canal is placed between the jugular fossa and carotid canal, and external to the termination of the aqueduct of the cochlea. The ramus tympamcus is figured and described by Arnoldf as dividing into six filaments : 1. a filament to the fenestra rotunda ; 2. one to the fenestra ovalis ; 3. one which anastomoses with the sympathetic; 4. one distributed upon the Eustachian tube ; 5. one, which he terms nervus petrosus profundus minor, anastomosing with {lie spheno-palatine ganglion ; 6. one, the nervus petrosus superfi- cialis minor, which anastomoses with a branch from the otic ganglion or ganglion Arnoldi. The nerve of Jacobson thus forms an anasto- mosis among the glosso-pharyngeal, the second"' and third branches of the fifth pair, and the superior ganglion of the sympathetic.;!; A small branch arises from the ganglion petrosum, as delineated by Arnold,§ which unites itself to the auricular branch of the par vagum.|| Two other filaments are generally found con- nected with that part of the trunk of the nerve occupied by the ganglion petrosum. These are a communicating twig between the ganglion petrosum and ganglion of the par vagum, and an anastomosing filament of the sympathetic. As these filaments are very minute, and lie in a dense fibrous sheath, they can only be displayed by an exceedingly careful dissection. The communicating filament between these two ganglia of the glosso-pharyngeal and par vagum is short, and passes directly from the one gan- glion to the other. The communicating filament from the sympathetic comes from the superior cervical ganglion, mounts up between the trunks of the par vagum and glosso-pharyngeal, and divides into two portions, — one of these connecting itself to the ganglion petrosum, the other to the ganglion of the par vagum. The course and mode of termination of this com- municating filament of the sympathetic is re- presented differently by Wutzerlf from the de- scription here given. I have adopted that given by Arnold,** since it exactly agrees with my own dissections. Another branch has been described as arising from the ganglion petrosum immediately below the ramus tympanicus, and passing backwards behind the styloid process, to anastomose with the trunk of the facial after * Acta Reg. Soc. Havniensis Medic, torn. v. Copen. 1818. f Icones Nervorum Capitis, tab. vii. 1834. $ Cruveilhier (Anatomie Descriptive, torn. iv. p. 952, 1835) states that, in one subject he found this ramus tympanicus formed by two branches, one from the par vagum, the other from the glosso- pharyngeal. In another subject it was formed by a branch from the auricular of the pneumo-gastric united with one from the glosso-pharyngeal. § Op. cit. plates iii and v. II It appears that the ramus auricularis of the par vagum was described even to both its branches by Comparetti, p. 129, De Aure Interna, &c. 1 Op. cit. fig. vii. ** Op. cit. tab. iv. its exit from the stylo-mastoid foramen * We here see that the anatomy of that portion of the glosso-pharyngeal nerve which lies within the foramen lacerum is very complicated, but it must be at the same time obvious that it em- braces considerations of great interest in a phy- siological point of view. What the true nature of these two ganglia is, we cannot at present venture positively to de- cide. I may mention, however, that Midler f states that he is satisfied, that the superior gan- glion or ganglion jugulare resembles the Casse- rian ganglion upon the trigeminus or fifth pair, and those upon the posterior roots of the spinal nerves, for while one portion of the nerve swells into a ganglion, the other passes by without assisting in its formation. On the other hand, he believes that the inferior gan- glion differs decidedly from those upon the posterior roots of the spinal nerves, and resem- bles the swelling which is occasionally found upon a nerve where it is joined by branches from the sympathetic. The ramus tympanicus, according to his view, belongs to the sympa- thetic system of nerves.}: On escaping from the foramen lacerum the glosso - pharyngeal occasionally forms direct anastomoses with the par vagum, spinal acces- sory, and superior ganglion of the sympathetic; at other times it only anastomoses with these through its branches. Digastric and stylo-hyoid branch. — The origin of this branch is far from being regular. It frequently arises from the external side of the nerve soon after its exit from the foramen lace- rum. It ramifies, as its name implies, in the digastric and stylo-hyoid muscles. The fila- ments of this nerve anastomose in the substance of the digastric muscle with the digastric branch of the portio dura.§ Carotid branches are two or more in num- ber, and pass from the convexity of the nerve or from some of its pharyngeal branches, and proceed upon the surface of the internal carotid, where they form a very evident anastomosis with the sympathetic, with the pharyngeal, and other branches of the par vagum, and assist in form- ing the plexuses around the carotid arteries. They have been traced downwards for a consi- derable extent, and found to anastomose with the superior and even with the middle cardiac nerves. Pharyngeal branches. — The nerve next fur- nishes the pharyngeal branches, which are from two to four in number. The largest of these proceed downwards, and their ramifications can be traced over the whole of the pharynx, but more particularly over its upper and middle * Cruveilhier, op. cit. p. 953. He looks upon this twig as the rudiment of a considerable branch of the facial, which he found in one case partly to replace the glosso-pharyngeal. See also torn. iii. p. 424. t Archiv. fur Anat. &c. No. ii. 1837, p. 276. % Handbuch der Physiol. Erster Band. § Mr. Swan, in plate xvii. fig. 2 and 3, of his " Demonstrations of the Nerves of the Human Body," figures this communication as formed by a filament of the digastric branch of the facial going to join the trunk of the glosso-pharyngeal. GLOSSOPHARYNGEAL NERVE. 49T portions. One or generally more of these pha- ryngeal branches perforate the stylo-pharyngeus muscle, and can be traced partly downwards up- on the middle constrictor, partly upwards upon the superior constrictor and mucous membrane of the fauces, and also partly forwards upon the surface of the tonsils. 1 have traced one of these pharyngeal branches through the posterior part of the hyo-glossus muscle into the mucous membrane at the side of the posterior part of the tongue. These pharyngeal branches, by their anastomoses with the pharyngeal branches of the par vagum and pharyngeal branches of the sympathetic, form what is called the pha- ryngeal plexus of nerves!* A distinct swelling is frequently found over the internal carotid artery, formed by the confluence of the princi- pal pharyngeal branches of the glosso-pharyn- geus, of the superior pharyngeal branch of the par vagum, and the pharyngeal branches of the superior ganglion of the sympathetic. This swelling varies considerably in size and appear- ance. Huberf describes a small ganglion in the pharyngeal plexus. Haase^ shortly de- scribes this swelling as a gangliform enlarge- ment. Wrisberg ;§ states that a ganglion, of the size of the ophthalmic, is placed at the conflu- ence of these nerves. Scarpa|| describes and figures it as a gangliform plexus more particu- larly connected with the pharyngeal branch of the par vagum. Wutzer^f states that he has been unable to detect this pharyngeal ganglion. Kilian** and Arno!d,tf but more particularly Rilian, figure it as a plexus. Though I would not deny the occasional existence of a small ganglion in this region, yet I believe it will be found that this swelling is generally formed by the cellular tissue binding together these branches as they anastomose with and cross each other. \t Lingual branches. — After the trunk of the nerve lias furnished the pharyngeal branches, it sends off from its concave side some small twigs upon the surface of the tonsils. It then forms the lingual portion of the nerve, passes into the base of the tongue below the stylo- glossus and posterior margin of the hyo-glossus muscle, where it divides into three or four branches. The superior of these is principally distributed upon the posterior part of the sides of the tongue, and sends some twigs backwards upon the palato-glossus muscle and mucous membrane of the fauces, where they anastomose with the other tonsillitic twigs. The middle part of the termination of the nerve passes * A small twig from the hypo-glossal nerve can sometimes be traced into this plexus. As the su- perior pharyngeal branch of the par vagum is partly formed by the spinal accessory, this last nerve must assist in the formation of this plexus. t Op. cit. p. 18. X De Nervo phrenico dextri lateris duplici, &c. Ludwig, torn. iii. p. 115. § Op. cit. p. 58. jj Tabulae Neurologicae, plate 2. 1 Op. cit. p. 91. ** Op. cit. tab. ii. fig. 5. tt Op. cit. tab. iv. XX The glosso-pharyngeal in the dog is generally considerably increased in size where the principal pharyngeal branches are given off. VOL. II. through the lingualis and hyo-glossus muscles to reach the mucous membrane and papilla; at the side of the base of the tongue. The re- mainder of the nerve perforates the genic-hyo- glossus to reach the mucous membrane and papilla? in the middle of the base of the tongue. The distribution of these twigs is confined to the mucous surface at the base of the tongue, and do not extend beyond an inch in front of the foramen coecum. They pass through the muscles of the tongue without giving any fila- ments to them.* Tonsillitic twigs. — The different twigs of this nerve which we have described as passing to the tonsils, form„an intricate plexus, posterior to and around these bodies, which has been called the circulus tonsillaris. These tonsillitic twigs are ultimately intermixed with the as- cending filaments of the pharyngeal branch of the par vagum, and pass in considerable num- bers to the isthmus of the fauces and soft palate. They anastomose also with the pos- terior palatine branches of the second branch of the fifth pair, and, according to Wrisberg,f with a filament from the third branch of the fifth. In repeated dissections, both upon the hu- man subject and the dog, I have found, in tracing the branches of this nerve to their ulti- mate distribution upon the pharynx and fauces, that those branches of the glosso-pharyngeal which do not anastomose with the pharyngeal branch of the par vagum are principally distri- buted upon the mucous membrane, and that comparatively a small number of these fila- ments seem to terminate in the muscular fibre. The uncombined twigs of the pharyngeal branches of the par vagum are, on the other hand, distributed entirely to the muscular fibre. In a dissection of this kind care must be taken to select those twigs only which proceed to their distribution without exchanging filaments with any other nerve. It can be made more favourably in the dog than in the human spe- cies. The glosso-pharyngeus is still distri- buted upon the tongue in birds, in the frog, and certain of the amphibia, while this organ receives no branch from the fifth pair, and from this circumstance it has been considered the nervus gustatorius of these animals. J In fishes there is a branch of the par vagum called glosso-pharyngeal, which escapes from the base of the cranium by a separate opening, and is distributed upon the gills, and also upon the tongue as far as the skin of the mouth. Physiology. — It is only to the labours of anatomists and physiologists within the last few years that we are to look for any thing * In tracing these nerves, it has appeared to me that a few minute filaments terminate in the mus- cles of the tongue, but these are exceedingly few and small. The statement of Wrisberg, that the deep branches of the lingual portion of the glosso- pharyngeal are distributed to the muscles of the tongue, is opposed to the observations of the best anatomists, who have since his time examined the ultimate distribution of this nerve. + Op. cit. p. 51. X Handbuch der Physiologie, etc. ErstcrBand, p. 590, 772. 2 L 498 GLOSSO-PHARYNGEAL NERVE. like accurate data in enabling us to judge of the functions of this nerve. Its deep situa- tion, its proximity to important parts, and the consequent difficulty of exposing it in the living animal, have until very lately deterred physio- logists from making it an object of experimental investigation. Some have supposed that it supplies the nervous filaments upon which the sense of taste at the root of the tongue de- pends, while the third branch of the fifth pair furnishes those of the anterior part of this organ. Mr. Mayo* states that " when this nerve is pinched in an ass recently killed, a distinct convulsive action ensues, apparently including and limited to the stylo-pharyngeus muscle and upper part of the pharynx." He concluded from this that the glosso-pharyngeal is in part, probably, a nerve of voluntary mo- tion ; and from its distribution upon the sur- face at the root of the tongue, that it is also partly a nerve of common sensation. Sir C. Bell believes that this is the respiratory nerve of the tongue and pharynx, associating the movements of those organs with the muscles of respiration in speech and in deglutition. And we find it stated by Mr. Shaw f that its power of combining the movements of the tongue and pharynx in deglutition " has been shown by several experiments, the results of which were very curious, and corroborative of the views deduced from comparative anatomy." Panizza} has undertaken an experimental in- vestigation into the functions of the nerve, and obtained very unexpected results. From these we are led to believe that when this nerve is pricked in a living animal, this is attended by no indications of suffering and no convulsive movements ; that section of both nerves is followed by loss of taste, while the tactile sensibility of the tongue and the mus- cular movements of deglutition and mastication remain unimpaired ; that section of the fifth pair is on the contrary followed by loss of common sensation without any apparent effect upon the taste. From these and other experi- ments upon the nerves supplying the tongue, he concludes that the glosso-pharyngeal is the nerve upon which the sense of taste depends, and is therefore the true gustatory nerve. Dr, M. Hall and the late Mr. Broughton§ had, from experiments performed previous to the publication of those of Panizza, arrived at the conclusion that this nerve is not a nerve of com<- mon sensation. These gentlemen likewise reported at the meeting of the British As-< sociation for 1836 an experiment, the results of which were in exact accordance with those obtained by Panizza upon this nerve, but no details of these experiments have yet been pub- * Anatomical and Physiological Commentaries, n. ii. p. 11. 1822. + London Medical and Physical Journal, vol. xlix. 1823. X Edinburgh Medical and Surgical Journal, Jan. 1836, and Medical Gazette, Sept. 1835. § Fourth Report of British Scientific Association, and Mr. Broughton, in vol. xlv. of Edinburgh Me- dical and Surgical Journal. lished. Mr. Mayo* has stated several objec- tions to these conclusions of Panizza. He rests his grounds of dissent principally upon the fact that the distribution of this nerve is con- fined to the posterior part of the tongue ; while the sense of taste, he maintains, is also present in the anterior part of that organ, and consequently it cannot, in that part at least, depend upon the glosso-pharyngeal. The persistence of the sense of taste after section of the fifth pair may, Mr. Mayo supposes, depend upon the palatine twigs of the second branch of the fifth pair distri- buted upon the palate and isthmus of the fauces. Mr. Mayo attempted to decide the matter by experiment, but he did not carry this suffi- ciently far to obtain any satisfactory results. Dr. Alcockf has also lately examined into the functions of this nerve experimentally, and has arrived at conclusions at direct variance with those of Panizza; for according to Dr. Alcock, when this nerve is exposed and irritated in the living animal, it excites pain and spasmodic contractions of the pharynx and muscles of the throat. When divided on both sides, the ani- mal's taste, " to say the least of it, did not ap- pear to be much affected." He believes that the sense of taste enjoys " two media of percep- tion, and that these are the glosso-pharyngeal nerve and the lingual and palatine branches of the fifth." He also states that the muscular movements of deglutition are very much im- paired after section of the nerve on both sides. He concludes, then, that the glosso-pharyngeal are sentient nerves, and also influence muscular motion. He, however, is doubtful in what manner these muscular movements are excited by irritation of this nerve, for though " dis- posed to regard the result in question as the effect of a sentient impression excited through the nerve, and referred to the interior of the pharynx," from the fact that this movement ex- tends to muscles not supplied by this nerve, and forms an associated movement, he admits " that the circumstance may be as well ex- plained by an exalted degree of muscular excitement, or by a higher one than that ne- cessary to produce the simple starting." Pro- fessor Miilier J believes that an examination of the position of the ganglion jugulare will de- cide that the glosso-pharyngeal is a mixed nerve, and he maintains that the distribution of this nerve, partly for sensation (mucous mem- brane of the root of tongue), partly for the movements of muscles (stylo-pharyngeus and pharynx), exactly resembles that of the two roots of the nervus trigeminus. Unable amidst these discordant statements to come to any sa- tisfactory conclusions upon the proper func- tions of this nerve, I entered into a lengthened experimental and anatomical investigation for this purpose. The experiments were twenty- seven in number, and were performed upon as * Medical Gazette, Oct. 1835, and 4th edit, of Outlines of Physiology, p. 314. f Dublin Journal of Chemical and Medical Sci- ence, Nov. 1836. X Archiv fiir Anat. und Physiol, etc. n. ii. 1837, p. 276. GLOSSO-PHARYNGEAL NERVE. 499 many different dogs. Seventeen of these were upon the living animal, with the view of as- certaining if this nerve were to be considered both a nerve of sensation and motion, and what are the effects of its section upon the associated movements of deglutition, and on the sense of taste. The other ten were performed on ani- mals immediately after they had been deprived of sensation, for the purpose of satisfying my- self to what extent it was to be considered a motor nerve. The most remarkable effect wit- nessed in these experiments was an extensive convulsive movement of the muscles of the throat and lower part of the face on irritating this nerve in the living animal, provided the irritation was applied to the trunk of the nerve before it had given off its pharyngeal branches, or to one of these pharyngeal branches sepa- rately. These movements were equally well marked upon pinching the cranial end of the cut nerve after it had been divided at its exit from the foramen lacerum, as when the trunk of the nerve and all its branches were entire. In some of these experiments we observed a remarkable difference between the effects of irri- tating this nerve before and after it had given off its pharyngeal branches, which is valuable on this account, that it may explain the discrepan- cies between the results obtained by Panizza, Dr. M. Hall, and the late Mr. Broughton on the one hand, and Dr. Alcock on the other. For though I do not mean to affirm that pinch- ing the lingual portion of the nerve is never followed by indications of suffering, (for from the irregularity in the origin of the pharyngeal twigs, and the difficulty of judging at the bottom of a deep wound in the living animal at what particular part these are all given off, it is generally impossible to decide where the lingual portion may be said to begin,) yet I have no hesitation in saying that if in several of these experiments we had operated only on that portion of the nerve which first presented itself, and not proceeded to dissect it back- wards towards its place of exit from the cra- nium, we should have gone away with the impression that the irritation of this nerve was followed by no convulsive movements, and little if any indications of suffering. From a review of all the experiments which I have performed upon the glosso-pharyngeal nerves, I am inclined to draw the following conclusions : — 1. That this is a nerve of common sensation, as indicated by the unequivocal expression of pain by the animal, when the nerve is pricked, pinched, or cut. 2. That mechanical or chemical irritation of this nerve before it has given off its pha- ryngeal branches, or of any of these branches individually, is followed by extensive muscular movements of the throat and lower part of the face. 3. That the muscular movements thus ex- cited depend, not upon any influence extending downwards along the branches of the nerve to the muscles moved, but upon a reflex action transmitted through the central organs of the nervous system. 4. That these pharyngeal branches of the glosso-pharyngeal nerve possess endowments connected with the peculiar sensations of the mucous membrane upon which they are distri- buted, though we cannot pretend to say posi- tively in what these consist. 5. That this cannot be the sole nerve upon which all these sensations depend, since the perfect division of the trunk of the nerve on both sides does not interfere with the perfect performance of the function of deglutition. 6. That mechanical or chemical irritation of the nerve, immediately after the animal has been killed, is not followed by any muscular movements when sufficient care is taken to in- sulate it from the pharyngeal branch of the par vagum. And we here observe an important difference between the movements excited by irritation of the glosso-pharyngeal and those of a motor nerve, for while the movements pro- duced by the irritation of the glosso-pharyngeal are arrested as soon as the functions of the central organs of the nervous system have ceased, those from irritation of a motor nerve such as the pharyngeal branch of the par vagum, continue for some time after this, and when all connexion between it and the medulla oblongata has been cut off by the section of the nerve. 7. That the sense of taste is sufficiently acute, after perfect section of the nerve on both sides, to enable the animal readily to recog- nize bitter substances. 8. That it probably may participate with other nerves in the performance of the function of taste, but it certainly is not the special nerve of that sense. The sense of thirst which is referred to the fauces and pharynx does not appear to de- pend entirely upon the presence of this nerve. The animals in which it was divided lapped water of their own accord. I observed one of those in which the nerves were found satisfac- torily divided, rise, though feeble, walk up (o a dish containing water, lap some of it, and return again to the straw upon which he was previously lying. In all experiments upon the glosso-pharyn- geal nerve in the dog, too great care cannot be taken to avoid the pharyngeal branch of the par vagum, which is sometimes situated in im- mediate contact with it, at other times one or two lines below it, and is frequently united to it by a considerable communicating branch, so that it may readily be mistaken for a large pha- ryngeal branch of the glosso-pharyngeal. This precaution is the more necessary, as I am con- fident that these two nerves differ from each other in function, and this must consequently seriously affect the results. I attribute the dif- ficulty of deglutition after section of this nerve in the living animal, and the muscular move- ments on irritating it in the animal recently killed, observed by two of the preceding ex- perimenters, to a want of sufficient precaution irf separating these nerves from each other. These results were only observed by me when the pharyngeal branch of the par vagum was im- plicated in the experiment. 2 L 2 509 GLUTEAL REGION. With regard to the argument in favour of the motal properties of this nerve, drawn by Muller from its anatomy, it appears to me that this analogical mode of investigation, valuable though it is, must be permitted to yield to the more positive observations obtained from expe- riment. And though it may be granted that the apparent limitation of the ganglion jugu- lare to the posterior filaments of this nerve causes it here to resemble closely the double roots of the spinal nerves, yet we must be wary in drawing analogies between the glosso- pharyngeal and spinal nerves, since we have another ganglion situated immediately below this, viz. the ganglion petrosum, which involves the whole of the nerve, and to this assuredly we have no analogical structure in the spinal nerves. No doubt Miiller supposes that this inferior ganglion differs from those placed upon the posterior roots of the spinal nerves, and that it. belongs to the sympathetic system. But as nothing like conclusive proof is advanced in support of this opinion, we may in the mean time reasonably suspend our belief as to the probable influence which this lower ganglion may exert upon the functions of the nerve. Of course the fact that some of the filaments of the glosso-pharyngeal terminate in the mus- cular fibre, is no proof that these filaments are motal, for the muscular bundles have their sen- sitive as well as their motal filaments. (John Reid.) GLUTEAL REGION, (Surgical Anatomy.) (Fr. region fessiere.) The gluta?al region may be defined with tolerable precision to be all that space external to the pelvis which is covered by the glutaei muscles of each side. Its boun- daries seem naturally to be the crista of the ilium above; behind, the mesian line as low down as the point of the coccyx ; before, a line drawn from the anterior superior spinous pro- cess of the ilium to the trochanter major; and below, a line drawn from the point of the coccyx to the insertion of the glutaeus maximus; in fact, the inferior margin of this muscle forms the boundary line. These limits, better defined than those of most of the anatomical regions, separate this tract from the lumbar and iliac regions above, from the superior anterior region of the thigh in front, from the perineal and posterior regions of the thigh below, and from the corresponding part of the opposite side at the posterior mesian line. This space, which does not comprise many points of importance in surgical anatomy, is yet not without interest. Here are the glutseal and ischiadic arteries, also the commencement of the course of the great sciatic nerve. The internal pudic artery also skirts along the inferior edge of the gluteal region, but this will be best considered as part of the region of the perineum. The first thing that strikes us in the exami- nation of this region is the great density and thickness of the integuments ; they are inferior in this respect only to the sole of the foot. This density is, however, found greater pro- portionally in the true skin than in the cuticle, which retains much of the softness and pliabi- lity of the same covering in other parts of the body, and the end of this is evident, since whatever the pressure may be upon the gluttsal parts, a dense state of the cuticle in any degree similar to the sole of the foot would, in the varied positions and movements of the trunk, be quite incompatible with comfort. On the other hand, the true skin, though pliant, is remarkably dense and strong, its fibres almost tendinous in structure, interlacing each other in every direction, and united underneath to a strong but rather loose cellular tissue which connects it to the gluteus muscle. It is to the laxity of this cellular connexion that the inte- guments of this part are partly indebted for that pliability which enables us to rest with ease and comfort upon surfaces of various degrees of hardness and inequality. It contains a considerable quantity of fat, which adds to the softness and elasticity of this cushion, and is very different from the granular hard fat found in the plantar region. The density of the integumental covering of the gluteal region varies somewhat in different parts. It is greatest where it covers the tuber ischii, and gradually diminishes on all sides except on the side next the perineum, where the change is very abrupt from its characteristic density to the extreme thinness and delicacy of the perineal covering. The peculiarity of structure of the integument covering the glutaei should be borne in mind by the surgeon in the treatment of diseases of this part. Abscesses should on this account be earlier opened from the obstacle thus pre- sented to their pointing. It is on this account also, probably, that we so generally find abscesses here accompanied with sloughing of the cellular tissue, which is best, obviated by an early opening. The fleshy fibres of the gluteus maximus are covered by a somewhat denser stratum of cellular tissue, forming an aponeurosis distinct from the fascia lata of the thigh, though conti- nuous with it at the anterior edge of the muscle, where the fascia lata lies upon the anterior half of the glutaeus medius. The great glutaeus is composed of coarse and loosely connected fasciculi, running in a direction downwards and forwards. It commences by a somewhat semicircular line of origin from the posterior two-thirds of the crista ilii, from the side of the sacrum and of the coccyx. From this origin the fibres run somewhat converging towards the great trochanter and upper pait of the linea aspera. This direction of the fibres should be borne in mind in connexion with all remedial manipulations on this part, that the position in which the limb should be placed may be chosen most favourably for the relaxing of the muscle. The other muscles which are in this neighbourhood, and all of which move the thigh-bone, are so much smaller than this great muscle that the relaxing of this is of the first importance, and the position must be chosen with reference almost entirely to this. On reflecting the glutseus maximus the fol- lowing parts are brought into view : — 1st, several large branches of arteries and veins, which were divided m reflecting the muscle, and which GLUTEAL REGION. 501 passed into the substance of the great gluteus muscle; these are from the gluteal and ischiatic arteries, and appear principally at the upper and posterior part of the gluteus medius; 2d, the whole of the gluteus medius, the pos- terior two-thirds of which had been covered by the larger muscle; 3d, at the posterior edge of the gluteus medius is thepyriformis muscle part- ly concealed by it, and coming out of the supe- rior sacro-sciatic foramen ; 4th, next below the piriformis lie the two gemelli, with the tendon of the obturator internus between them, and below these is the quadratus femoris, having underneath it the strong tendon of the obturator externus; 5th, the great sciatic nerve is seen emerging from the superior sacro-sciatic fora- men near the sciatic artery. Sometimes it comes out entirely below the piriformis; some- times it descends in two branches, one of which peiforates that muscle, and they then unite. The trunk passes directly downwards, cross- ing the rotator muscles of the hip, and pass- ing between the projecting tuberosity of the ischium and the trochanter major. In this part of its course it is accompanied by the sciatic artery, which is seen about half an inch to the internal or sacral side of the nerve, and sends one considerable branch to supply the nerve, and runs tortuously imbedded in its iieuri'.ema. The course which the nerve and artery here take will be represented by a line drawn from the posterior superior spinous pro- cess of the ilium to a spot midway between the tuber ischii and trochanter major. Lastly, in this view are exposed the bursal sacs, of which there are several between the gluteus maxim us and the subjacent parts. The most considerable is found between it and the external surface of the trochanter major. A consider- able but smaller one is placed between its broad tendinous expansion and the upper part of the vastus externus, and two smaller ones com- monly between the muscle and the os femoris at the upper and back part of the thigh. The ischiatic artery at the commencement of its course is smaller than the gluteal, and comes down over the pyriformis muscle, and makes its exit from the pelvis through the lower part of the sciatic notch, between the pyriform and levator ani muscles, above the lesser sciatic ligament, and in front of the sciatic nerve ; it sometimes passes between the roots of this nerve. On the dorsum of the pelvis the sciatic artery is covered by the gluteus maximus muscle, and may be seen by a similar dissec- tion to that which exposes the gluteal artery, excepting that it is found about an inch and a half lower down than the last-named vessel. The gluteal artery comes out of the pelvis at the upper part of the sciatic notch in com- pany with the superior gluteal nerve and vein. It immediately winds upwards upon the dorsum ilii, keeping close to the bone, and shortly after its arrival upon the dorsum it divides into branches principally distributed to the gluteal muscles. To expose this artery and its branches in dissection, it is necessary to proceed as in the dissection of the gluteus maximus muscle. Next divide this muscle in a line from the posterior superior spine of the ilium to the tuberosity of the ischium. In making this dis- section several large arteries and veins must be injured. If the edges of the muscle be now- separated and the subjacent cellular membrane removed, the gluteal artery, accompanied by one or two large veins and by the gluteal nerve, may be seen escaping from the sciatic notch above the pyriform muscle, between it and the gluteus medius. This artery, as it escapes from the pelvis, lies three inches and a half from the mesian line, or from the spinous processes of the sacrum. The gluteal and ischiadic arteries, as we have seen, are covered by the gluteus maximus mus- cle, and lie at such a depth from the surface that they are not very liable to injury. Wounds, however, of this part do occasionally implicate these vessels, either in their large branches or even the trunks themselves, and they have been affected with aneurism, an instance of which is mentioned by Mr. J. Bell,* and which attained a considerable size. In the case of a wound, its direction will lead us to the situation of the artery ; and in the instance of aneurism just mentioned, Mr. Bell ventured to lay open the sac and thus reach the mouth of the gluteal artery, which he secured by liga- ture, and this perhaps might be accomplished in a very emaciated person; but generally speaking the artery lies so deep, and the vessels which must be wounded in rhak ing the neces- sary incisions would by their bleeding so ob- scure the operation, that the most experienced surgeons do not recommend the attempt under ordinary circumstances, but prefer the operation of tying the internal iliac.f As a guide, how- ever, to the situation of the gluteal artery, whether in the examination of a wound or in operating upon it, its position on the dorsum of the pelvis may be ascertained by drawing a line from the posterior spinous process of the ilium to the middle of the space between the tuberosity of the ischium and trochanter major. If this line is divided into three, the gluteal artery will be found emerging from the pelvis at the juncture of its upper and middle thirds.! To return to the consideration of the anato- mical structures which we expose in succession. We are struck with the difference in texture of the three glutei muscles. The fibres of the two smaller glutei are of moderate size and strength, while those of the larger gluteus are remarkable for their coarseness and large dimen- sions. The relative situation of the three muscles is also important. The position and direction of the gluteus maximus is just in that line in which the greatest vigour of action is required to erect the body by drawing the back part of the pelvis towards the trochanter major. In this operation it is assisted by the position of the gluteus medius and minimus, * Principles of Surgery, vol. i. p. 421. f See Med. Chir. Trans, vol. v. Also Guthrie on Diseases of Arteries, p. 364. } See Harrison's Surgical Anatomy of the Arte- ries, vol. ii. p. 1U0. 502 GLUTEAL REGION. the posterior fibres of which are covered by the gluteus maximus. These anterior fibres have a different action, varying in the different posi- tions of the body in relation to the thigh, and, according to this, consisting either in rotation inwards, abduction, or flexion of the femur, or, this bone being fixed, assisting in the various anterior movements of the pelvis upon the thigh. At the posterior edge of the middle gluteus is the pynformis coming out of the upper open- ing of the sciatic notch. Here, as we have seen, the gluteal artery is also emerging from the pelvis and winding round the upper edge of the notch. This, therefore, will be the situa- tion of an aneurism of this artery, and a pul- sating tumour being detected in the situation just indicated by measure, as the seat of this vessel, will be a very strong ground for deciding both as to the disease and the vessel diseased. A case lately came under our notice of a very obscure character in which a swelling was situated precisely, in the position of the gluteal artery, but without pulsation or any other sym- ptom of aneurism. The swelling was at first indistinct, but as the surrounding parts wasted under the effect of disease it became more pro- minent. It was firm to the touch and rather moveable, and about the size of a hen's egg. But the principal part of the disease showed itself within the pelvis in a tumour consisting almost entirely of coagulum, as was proved by puncture, situated behind the rectum, and pressing it forward so as to occupy nearly the whole pelvis, and obstructing the passage both of faeces and urine. As there was no decided symptom of aneurism no operation was at- tempted for the relief of the case, and as the girl, who is eighteen years of age, still lingers, the nature of the disease is not yet cleared up. But this part also occasionally gives exit to a hernial tumour, part of the intestines or even the bladder or ovary becoming thus displaced and being lodged in the sac* The superior opening of the sciatic notch is bounded above by the notch of the ilium, before by the de- scending ramus of the ischium, and below and behind by the superior sacro-sciatic ligament; and so large is the opening thus left that we might expect to find the protrusion of some of the viscera of the pelvis much more frequently than we do. Yet so completely is this part covered and defended by the pyriform muscle, the plexus of nerves, the glutei maximus and medius, that this form of hernia is an extremely rare occurrence. When it does occur in the adult, the diagnosis is very difficult while the hernia is small, owing to the great depth at which it is situated. When, however, it is congenital, the nature of the swelling is larger in proportion to the size of the surrounding parts, and the depth of the superjacent parts less ; yet even here Professor Schreger did not at first detect the nature of the swelling. In fact nothing but the actual feeling of the guggling of the gas of the intestines under the finger seems sufficient * See a summary of cases of ischiatic hernia in Cooper's Fint Lines of Surgery. to discriminate the case, and this is of course not to be expected when the gut is strangulated. Indeed, in Dr. Jones's case* the symptoms were not at all referred by the patient to the true seat of the disease, and the surgeon was in consequence never led to make any external examination of this part. It may be well to state here the anatomical relations of the hernial sac in this case, which was carefully dissected. " A small orifice in the side of the pelvis, anterior to but a little above the sciatic nerve and on the fore part of the pyriformis muscle, led into a bag situated under the gluteus maxi- mus muscle, and this was the hernial sac, in which the portion of intestine had been stran- gulated. The cellular membrane which con- nects the sciatic nerve to the surrounding parts of the ischiatic notch had yielded to the pres- sure of the peritoneum and viscera. The orifice of the hernial sac was placed anterior to the internal iliac artery and vein, below the obtura- tor artery and above the obturator vein. Its neck was situated anterior to the sciatic nerve, and its fundus, which was on the outer part of the pelvis, was covered by the gluteus maxi- mus. Anterior to but a little below the fundus of the sac, was situated the sciatic nerve, behind it the gluteal artery. Above, it was placed near the bone, and below appeared the muscles and ligaments of the pelvis." We must not conclude this article without a few words on the general form of the gluteal region as affording an important means of diagnosis in disease. In examining this re- gion in a healthy person we observe, 1st, the thick rounded prominence of the nates, formed by the posterior and inferior margin of the gluteus maximus ; 2d, the projection of the trochanter major, only covered by the integu- ments and the thin tendon of the last-named muscle ; 3d, the projection of the crista ilii7 forming the upper boundary of the region ; 4th, a depression, perpendicular in direction, between the nates and the trochanter major ; 5th, another depression, slighter than the last and transverse in direction, between the tro- chanter and crista ilii. Now almost all these points become altered in character and relation in disease. In dislo- cation of the femur they of course are changed by the difference in position which the trochan- ter assumes in common with the head of the bone ; and according to the unnatural situation which this occupies, so will the alteration in the general form of the parts be modified. But we now speak particularly of the changes of disease. Even in the inflammatory stage of disease of the hip-joint, it is surprising how great is the effect produced upon the nates. The roundness and fulness gradually go, the nates looks wasted, and the depression between this and the trochanter disappears. This wast- ing, arising from interstitial absorption of the gluteus and parts adjacent, is the more striking as it occurs too rapidly upon the affection of the joint to be the effect of inaction of the * See Sir A. Cooper on Hernia, part ii. p. 67. HiEMATOSINE. 503 muscle, as we have seen it occur in a marked degree in a rather severe attack of inflammation of the joint, which readily yielded to treat- ment.* Then in the more advanced stages of disease of the joint, the depressions above mentioned are not only lost, but from morbid depositions in the neighbourhood of the hip they become elevated and swollen, and the sharp prominences of the trochanter lost in the general fulness of the part. (A. T. S. Dodd.) GROIN, REGION OF THE, (Surgical Anatomy.) (Fr. Vaine, region inguinale.) The limits of this region, as understood by most surgical writers, seem to be wholly artificial. The groin constitutes the confines of the ab- domen and the thigh ; and Poupart's ligament forms a natural line of division between its femoral and its abdominal portions. A line drawn horizontally, the subject being erect, from the anterior superior spinous process of the ilium to the linea alba, forms the superior limit of this region, while below it may be defined by a line parallel to the former one, and extending from the pubis to the outer part of the thigh. For the particulars of this region, see Hernia, Femoral Artery, Abdomen, and Thigh, regions of the. (R. B. Todd.) H^MATOSINE, (ai^a, blood, and tt.ttto, to fall.) The colouring matter of the biood.f This principle separates with the fibrine of the blood when that fluid coagulates, and may be obtained free from adherent albuminous matter by the process recommended by Berzelius, which is as follows. The coagulum is first to be sliced in thin pieces with a sharp knife, and then carefully washed in separate portions of distilled water; by these means we separate the adherent serum, and if the washing is gently performed, but little haematosine be- comes washed away with it. The slices thus prepared are placed on a filter and allowed to drain : when the draining is complete, the slices are to be thrown into a glass vessel and broken up in distilled water ; we thus procure a solution of the colouring matter while any fibrine pre- sent gradually subsides. The liquor when poured off is a tolerably pure solution of haematosine. If it is wished to procure the principle in the solid form, the solution may be evaporated at a temperature not exceeding 100° Fahrenheit. Engelhart prefers heating the solution after filtration to about 150° Fahrenheit, which deter- mines the precipitation of the haematosine, while any albumen which may possibly exist * There seems to be a law of the animal economy that when a joint is diseased the muscles moving it immediately lose tone and bulk, and there is no more marked symptom of disease of an articulation than this wasting of the muscles which belong to it. t Lecanu considers that haematosine is a com- pound of albumen with a substance which lie be- lieves to be the true colouring matter of the blood, and which he calls Olobuline. in solution with it, remains dissolved at that temperature. Engelhart's process yields us haematosine in its purest form, but when thus obtained it is no longer soluble in water, whereas, if procured by evaporation at 100° Fahrenheit, it is still soluble, and what is very extraordinary, dry haematosine procured at that temperature, though it be afterwards subjected to a heat of 212" Fahrenheit, does not lose its property of dissolving in water. Haematosine may be described under two forms, viz. in solution and in the dry state. The aqueous solution of hamatosine is pre- cipitated by alcohol and the acids. The alkaline hydro-sulphurets and sulphuretted hy- drogen change the colour of the solution to green ; nearly all the metallic and earthy salts precipitate it. Infusion of galls produces a pale red precipitate; gallic acid, however, does not show this effect. Chlorine passed through a solution of haematosine decolorizes it. Bromine produces a similar result, but it is some time before the effect is observed. Iodine will also decolorize the solution after some hours, and produces a brown precipitate, which is found to contain iodine. Haematosine when dry is of a dark red co- lour and exceedingly hard, having a vitreous fracture. Its chemical properties in many re- spects resemble those of fibrine, and albumen in the coagulated state. Berzelius remarks that, like fibrine, it contains a fatty matter pe- culiar to itself which can be separated by ether; this is one point of resemblance in the opinion of that chemist. The action of acetic acid on haematosine is a very striking point of resem- blance between that body and fibrine ; for when the acid in the concentrated state is al- lowed to remain in contact with haematosine for a few hours, we observe that it is converted into a tremulous brown mass which is more or less soluble in water, and which during solu- tion evolves nitrogen gas. The nitric, hydro- chloric, and sulphuric acids, if diluted with an equal bulk of water, and digested on haema- tosine, become coloured yellow and disengage nitrogen ; but they do not dissolve the prin- ciple even at a boiling heat. The results of such digestions, however, in the hydrochloric and sulphuric acids, are soluble in water; but that which has been digested in nitric acid remains insoluble. Potash, soda, and ammonia dissolve haema- tosine with facility, and it is precipitated from such solution by the addition of an acid. The acetic acid acts thus, but re-dissolves the pre- cipitate if added in excess, as it would albu- men or fibrine. Tannin precipitates haematosine from solu- tion in alkalies. Tiedemann and Gmelin have observed that boiling alcohol will dissolve haematosine ; this is also the case to a considerable extent with its combinations with several of the acids which precipitate it. When haematosine is incinerated and decarbonized, it yields an ash amounting to 1.3 per cent, of its weight: this, according to Berzelius, is composed of the following sub- stances : — 504 IJ/T.MATOSINE. Carbonate of soda, with traces of phosphate 0.3 Phosphate of lime 0.1 Caustic lime 0.2 Subphosphate of iron 0.1 Sesqui-oxide of iron 0.5 Carbonic acid and loss 0.1 1.3 The ultimate analysis of hoematosine ap- proaches very nearly to that of fibrine. Mi- chael is declares to have found a difference of ultimate constitution between the colouring matter of arterial and venous blood : his ana- lyses are as follows : — arterial. v enuii?. Nitrogen 17.253 17.392 Carbon 51.382 53.231 Hydrogen 8.354 7.711 Oxygen 23.011 21.666 It will be observed, on examining these ana- lyses, that the difference of constitution is so small that we may reasonably conclude it has been produced by a difference in manipulation or some other extraneous cause capable of modifying the result: indeed, ultimate ana- lyses of identical substances have, when in the hands of different chemists, often yielded re- sults far more discrepant than these, and that too when each operator stood high as an ana- lyst. Berzelius, in remarking on these expe- riments, observes that it is impossible for the chemist to fix the state of blood whether arterial or venous; for it will lose its condition with respect to the colouring matter long before the chemist can procure its haematosine for analysis. Thus the venous clot becomes of a bright red colour when exposed to air, and arterial blood soon loses its vermilion hue. A great con- trariety of opinion exists as to the cause of the red colour of hamatosine, some chemists sup- posing that the iron contained in it takes an active part in its coloration, while others maintain that though iron is present it cannot be considered as the cause of colour. Win- terl imagined he had discovered the secret when he formed sulphocyanic acid (blutsaure) by carbonizing blood with carbonate of potash and precipitated salt of iron with the lixivium — an experiment quoted by Treviranus ; but we are unable to detect the sulphocyanic acid in blood, so this formation of a ferruginoifs co- louring matter must not be considered as in any way assisting in the inquiry, although it simulates the tint of blood most completely. Fourcroy asserted that subphosphate of iron was capable of imparting a red colour to serum, which is not the case, and went so far as to declare that the colourless globules of the chyle contained neutral phosphate of iron, which, when mixed with the blood, was de- composed by the alkali present into a sub- phosphate, whicl) on reaching the lungs be- came a pei-salt and imparted colour to the fluid. This idea is quite hypothetical, and in discordance with facts as observed by other chemists. Engelhart's experiments on hsematosine tend to shew that iron is in some way influential in producing the red colour of the blood. He showed that, though albumen and fibrine yielded no iron on incineration, the metal ex- isted in considerable quantity in hasmatosine. He found that a solution of red particles im- precated with sulphuretted hydrot;en became of a violet colour and then passed to a green, it being impossible to restore the original red tint. Chlorine when passed through the solution bleached it, having previously produced a green colour ; when decolorization was com- plete, white flocculi were observed to fall, which on being examined yielded no. appre- ciable ash, while the clear solution gave evi- dence of iron by the usual reagents. The white flocculi were supposed by Engelhart to be the colouring matter changed to white by the abstraction of its iron. It is evident that even if the colour of the blood were owing to some peculiar animal matter and not to iron, we should still expect decolorization by chlo- rine ; but yet the change of colour from red to green which that re-agent produces previous to decolorizing the solution, renders it probable that its action is on iron in some form of com- bination as yet unknown. Rose has shown that many organic matters interfere with the action of the tests for iron when present in solution with that metal, and quotes this to account for the failures in procuring the re- actions of iron from the blood in a fluid state. Some experiments of Berzelius, however, have proved that the artificial combinations of iron with albumen which Rose formed, can be pre- cipitated by ferrocyanate of potassa if they are previously treated with acetic acid : as this does not happen with blood, it is very pro- perly contended that Rose's experiments are not to be looked upon as an explanation of the difficulty. In a paper published by Mr. Brande in the Philosophical Transactions for 1812, that gentleman proposes to consider hsmatosine as an animal dye, which like co- chineal is capable of uniting with metallic oxides ; thus the oxides of mercury and tin are active precipitants of this colouring matter, and woollen clothes previously impregnated with a solution of bichloride of mercury have been permanently dyed by steeping them in a solution of hsematosine. The question as to whether or not iron be really necessary to the existence of the red colour of the blood can- not be considered as determined, and it is difficult to imagine any line of experimenting which could afford results sufficiently satis- factory to settle the point. Mr. Brande's ex- periments, by which he concluded that haema- tosine contained iron in no greater proportion than fibrine or albumen, would have placed the matter beyond doubt if other chemists had confirmed" his observations ; but the expe- riments of Dr. Engelhart published in 1825, and which have received very general con- firmation, show that fibrine and albumen when pure contain no iron, and that the metal exists in considerable quantity in hrcmatosine. (G. 0. Rees.) BONES OF THE HAND. 505 HAIR. See Tegumentaf.y System. HAND, BONES OF THE, (Human Ana- tomy.) The hand (veig, wiaraws; Hi. la main; Germ, die Hand,) is the inferior segment of the upper extremity. Its presence is charac- teristic of man and the Quadrumana. Although formed on the same general type, the hand will be found to exhibit many points of difference from the foot — characters strongly indicative of the diversity of use for which it is designed. In examining the skeleton of the hand, we observe subdivisions analogous to those which exist in the foot — the carpus cor- responding to the tarsus, the metacarpus to the metatarsus, and the phalanges of the fingers in every way analogous to those of the toes. Independently of the lightness and mobility which are such prominent features in the me- chanism of the hand, when contrasted with that of the foot, the divergence of the first or radial finger ( the thumb ) from the line of direction of the other four, is peculiarly cha- racteristic of the band. Whilst the four fingers, properly so called, are parallel to the middle line of the hand, the thumb, when extended, forms with itan angle of rather more than 45°. To this position of the thumb is due in the greatest part the facility of opposing it to one of the fingers, a movement so necessary in the pre- hension of minute objects.* The general form of the hand i.s oval, the obtuse extremity corresponding to the tips of the fingers, the unequal lengths of which oc- casion the curvature in this situation. On its posterior surface or dorsum, the hand is convex ; on its anterior surface or palm, it is concave : both these surfaces correspond to, and in the recent state are supported by, the bones of the carpus and metacarpus. I. Carpus (Germ, die Handivurzel). The carpus bears a much less proportion in size to the whole hand than the tarsus does to the foot ; it forms scarcely more than one-fourth of the hand. Its outline is oval, the long axis being transverse : if examined in a hand to which the ligaments are attached, the carpus will be found to form the posterior and osseous portion of an osseo-ligamentous ring, which gives pas- sage to the tendons of the fingers. It is con- sequently hollowed from side to side, and is bounded on each side by a bony ridge, which gives attachment to the ligament ( annular ligament ) which forms the anterior part of the ring ; on the radial side the ridge is formed by a process of the os trapezium and of the sca- phoid ; on the ulnar, where there is a more prominent ridge, by a process of the unciform bone, and by the os pisiforme. Seven bones, arranged in two rows, form the carpus. The superior row consists of the os navicu/ure, as lunare, and os cuneiformc, to which last is articulated a bone, constantly reckoned as a carpal bone, but which, I con- ceive, may be more correctly regarded as a sesamoid bone, the us pisiforme. The second * See the prefatory observations to the article Foot. or inferior row is formed by the os trapezium, os trupezoides, os magnum, and os unciforme. 1 . Os naviculare (os scuphoideum ; Fr. le scaphotde ; Germ, das Kahnbem). The na- vicular or scaphoid is the largest of the upper row, and likewise the most external. Its su- perior surface is convex, oval, with long axis transverse, articular, and is adapted to the outer part of the carpal articular extremity of the radius. The hollowed surface, to which it owes its name (boat-like ), is directed down- wards and inwards ; this is likewise articular and receives the head of the os magnum : con- tinuous with and to the inner side of this hollow surface, there is a plane one of a semi- lunar form, with which the os lunare is articu- lated. The scaphoid bone articulates with the trapezium and trapezoides, by a convex surface directed downwards and outwards. Externally this bone terminates in a pointed extremity which receives the external lateral ligament of the wrist-joint and the annularligament ( tuber- culum ossisnaviculuris, s.eminentia carpiradialis superior). The anterior and posterior surfaces of the bone are rough, and give attachment to the anterior and posterior radio-carpal ligaments. 2. Os lunare, (os semilunare v. iunatum ; Fr. le. semilunaire ; Germ, das Mondbein), situated between the scaphoid and the cunei- form bones, it presents four articular surfaces ; an upper one, convex and somewhat triangular in its outline, articulated with the radius; an inferior one, very much hollowed from before backwards (to the crescentic form of which the bone owes its name), articulated with the os magnum; an external surface, plane and square, adapted to the cuneiform bone ; and, lastly, an internal surface, by which it articu- lates with the scaphoid. 3. Os cuneiforme (os triquetrum s. pyra- midale; Fr. le pj/ramidale; Germ, dasdreiseitige Bein). This bone terminates the superior carpal row on the ulnar side; its upper surface is partly smooth, encrusted with cartilage in the recent state, where it is in contact with the triangular ligament of the wrist-joint, and partly rough where it gives attachment to liga- ments. Externally it articulates with the cunei- form bone, and inferiorly with the unciform by a large and concave suaface. The inner half of its anterior surface articulates with the pisiform bone, and the radial half of the same surface is rough for ligamentous insertion. The three bones just described, constituting the superior row of the carpus when united, present on their superior aspect a convex arti- cular surface which forms the carpal portion of the radio-carpal joint, the scaphoid and lunar being articulated with the radius, while the cuneiform glides upon the triangular carti- lage of the wrist. 4. Os pisiforme (from pisum, a pea; Fr. le pisiforme; Germ, das Erbsenbein). This little bone projects at the anterior part of the ulnar extremity of the superior carpal row; it forms what some anatomists designate eminentia carpi ulnuris superior, being part of the bony ridge already referred to on the ulnar side of the carpus. The prominence produced 506 BONES OF THE HAND. by this bone is easily felt during life, more especially during flexion of the wrist-joint. It is round every where, except posteriorly, where it presents a flat circular surface, by which it is articulated with the cuneiform bone. This bone is intimately connected with and as it were inclosed in the terminal portion of the tendon of the flexor carpi ulnaris. 5. Os trapezium (os multangulum majus ; Fr. le trapeze ; Germ, das grouse vielysinkliche Bein ). This bone is situated at the radial extremity of the inferior carpal row, having the scaphoid above it and the metacarpal bone of the thumb below it. We may describe six surfaces upon it, four articular and two non- articular, a. A large articular surface, situated on the external and inferior aspect of the bone. This surface is for articulation with the meta- carpal bone of the thumb : it is somewhat oval in form, the long axis passing from without inwards and downwards ; in this direction it is concave, from before backwards it is convex. The three remaining articular surfaces are on the internal and superior aspects of the bone. b. Internally, a very small plane surface, adapted to a corresponding one on the radial side of the carpal extremity of the second metacarpal bone. c. Above the last described surface and separated from it merely by a slight ridge, we find one of a somewhat triangular form and slightly concave, articulated with the radial side of the trapezoid, d. Quite on the superior aspect a small semicircular surface, adapted to the scaphoid. Of the non-articular surfaces, one is on the palmar aspect of the bone, and is easily distinguished by the prominent ridge or tubercle at its outer part, which gives attach- ment to the annular ligament, ( tuberculum, eminent ia carpi radialis inferior ;) and on the ulnar side of this ridge a groove in which the tendon of the flexor carpi radialis glides. The second non-articular surface is on the dorsal aspect : it is more extensive than the last, rough and tuberculated, affording insertion to ligaments. 6. Os trapezoides (os multangulum minus; Fr. le trapezoide ; Germ, das K/eine viel- winkliche Bein ). This is the second bone of the inferior carpal row ; it has the os trapezium on its radial and the os magnum on its ulnar side, the scaphoid above and the second meta- carpal bone below it. We describe four articular surfaces and two non-articular, a. The inferior one the largest, quadrilateral, much narrower in front than behind, convex from side to side, slightly concave from before backwards, is entirely devoted to articulation with the second metacarpal bone. b. On the radial side, a slightly convex surface for the trapezium. c. Superiorly a quadrilateral concave surface for articulation with the scaphoid, d. On the ulnar side a very small surface, adapted to a corresponding one on the radial side of the os magnum. The palmar surface is non-articular, five-sided, slightly excavated, and rough from the insertion of ligaments. The dorsal surface, also non- articular, is of greater extent, con- vex, and likewise rough. 7. Os magnum ( os capitatum ; Fr. le grand os; Germ, das Kupfbein). This bone is, as its name implies, principally characterized by its excess in size over the other carpal bones, and from the number of bones with which it is connected, it may be regarded as the key-bone of the carpus. Superiorly it is in the form of a rounded head (capitulum), flattened on the ulnar side, where it articulates with the unciform bone. The superior prominent portion of this head is received into the excavation of the lunar bone, and by its radial side it articulates with the inferior hollow surface of the scaphoid. The inferior portion of the bone is cuboid, and has been called the body ; it is rough and con- vex on its palmar surface, also rough but irregular on its dorsal, both these surfaces affording insertion to numerous ligaments. Inferiorly we notice an extensive articular sur- face, which is adapted in the centre to the third metacarpal bone, on the radial side to the second, and by a very small portion on the ulnar side to the fourth metacarpal bone. On the ulnar side of its inferior portion it articu- lates a second time with the os unciforme by a small circular articular surface, the cir- cumference of which nearly equals that of the flat surface of a split pea. Lastly, on its radial side it articulates with the trapezoid bone. Thus the os magnum articulates with seven bones ; three metacarpal bones, two carpal bones in the inferior row, and two in the supe- rior row. 8. Os unciforme (from uncus, a hook, os ha- matum; Fr, p os crocliu ou unciforme; Germ. das Hakenbein, oder Keilformiger Knocfien ). This bone has received its name from that which allows of its being easily distinguished from all the carpal bones, — namely, the hooked process, which projects from the radial edge of its palmar surface. This process constitutes a considerable prominence on the ulnar side of the carpus (eminentia carpi ulnaris inferior ), and affords insertion to the annular ligament. Its concavity looks towards the radial side of the carpus ; the remainder of the palmar sur- face is rough for ligamentous insertion. The dorsal surface is likewise rough, convex, and of considerable extent. This bone articulates inferiorly with the fourth and fifth metacarpal bones, on its radial side with the os magnum, and on its superior surface with the cuneiform bone. Structure of the carpal bones. — These bones are chiefly composed of the reticular osseous tissue, to which their extreme lightness is attri- butable, the surface being invested by a thin layer of compact texture, in this respect per- fectly resembling the bones of the tarsus. Developement. — The carpal bones are very late in their developement; at birth they are completely cartilaginous. According to Cru- veilhier, each bone is developed by a single point of ossification. The os magnum and os unciforme are the first in which the ossific pro- cess commences, about the end of the first year; between the third and fourth years it begins in the cuneiform, a year later in the trapezium and lunar, and between the eighth and ninth years in the scaphoid and trapezoid bones. The ossification of the pisiform does BONES OF THE HAND. 507 not begin till between the twelfth and fifteenth years, and Cruveilhier states that of all the bones of the skeleton it is the last in which the process of ossification is completed. II. Metacarpus (Germ, die Mdtelhand). Five bones constitute the metacarpus, the four internal ones being parallel to each other, the external one diverging outwards at an acute angle with the middle line of the hand. These bones vary in length from about two inches and a half to one inch six-eighths. They articulate inferiorly with the superior or metacarpal pha- langes, and superiorly with the carpus. Each metacarpal bone presents two extremi- ties, and a shaft or body between them. The superior or carpal extremity is expanded and wedge-shaped, the broader part being towards the dorsal aspect. Three articular surfaces exist on each ; one, the most extensive, on the superior or carpal surface, for articulation with a carpal bone ; the other two on the radial and ulnar surfaces, adapted to the adjacent meta- carpal bone or to a carpal bone. The palmar and dorsal surfaces are rough and irregular, and afford insertion to the ligaments which strengthen the earpo-metacarpal joints. The inferior or digital extremity is in the form of a rounded head, flattened on each side, where we notice a depression, and behind it a tubercle which affords insertion to the lateral ligament of the joint. The smooth articular surface of the head extends further upon the palmar sur- face of the bone than upon its dorsal surface, or, as in the case of the metatarsal bones, more on the side of flexion than on that of extension. The shaft or body is prismatic and slightly curved, so as to present a concavity towards the palmar surface, and a convexity to the dorsal. The metacarpal bones are numbered from without inwards. The first, or that of the thumb, is the shortest of all and likewise the thickest. Its carpal extremity will likewise serve to distinguish this bone ; it wants the cuneiform shape, and is rather wider on its palmar than its dorsal surface. It has no arti- cular facets on its sides, being articulated with the trapezium alone by means of a surface which is concave from before backwards, and convex from side to side; the body of this bone is flatter on its palmar and dorsal surfaces than any of the others. The second metacarpal bone is the longest ; it, however, exceeds the third by a very slight difference. It is further distinguished from the third by the diminutive size of the articular facet on the radial side of its carpal extremity. The third, metacarpal bone, though shorter than the second, is manifestly thicker and stronger; this excess of developement being attributable to its affording insertion to one of the most powerful muscles of the hand, — ■ namely, the adductor pollicis. The fourth and fifth metacarpal bones are shorter and in every way smaller than the pre- ceding ones. The fifth is shorter and somewhat thicker than the fourth : it has no articular facet on the ulnar side of its carpal extremity, but presents a prominent tubercle in that situation for the insertion of the extensor carpi ulnaris. The structure of the metacarpal bones is the same as that of the long bones in general. Developement. — There are two points of ossification for each metacarpal bone, one for the body and the carpal extremity, the other for the digital extremity. The first metacarpal bone, however, according to Cruveilhier, offers an exception to this, inasmuch as its carpal extremity is developed from a point of ossifica- tion distinct from that of the body. In some instances there are three points of ossification for each metacarpal bone. The bodies of the metacarpal bones are completely ossified at birth. Between the second and third years appear the points for the inferior extremity in the four inner bones and the superior extremity in the first, but the complete fusion of the extremities with the shafts does not take place till near the twentieth year. III. Fingers ( dixit i; Fr. les doigts ; Germ. die Finger ). The fingers differ strikingly from the toes as regards their length, to which, in- deed, is due their greater mobility. They are numbered in proceeding from the radial to the ulnar side of the hand. All except the thumb are composed of three phalanges, the superior or metacarpal, the middle, and the inferior or lingual: in the thumb the middle phalanx is absent. The fingers differ considerably in length ; the thumb is by far the shortest, and the middle finger is the longest. Next in length is the ring finger, then the index, and last and least the little finger. The metacarpal phalanges have the following general characters: — 1st, a body slightly con- cave from above downwards on the palmar surface, and convex on the dorsal ; 2d, a supe- rior or metacarpal extremity more expanded than the inferior, hollowed into an articular surface for the head of the metacarpal bone ; and 3d, an inferior extremity, having a pulley- like surface for articulation with the middle phalanx. The metacarpal phalanges are the longest. The middle phalanges present the same cha- racters as the preceding as regards the body. The superior extremity has a pulley-like articu- lar surface, convex transversely ; that of the inferior extremity being concave in the same direction. The ungual phalanges are readily distin- guished by the inferior or ungual extremity, which is rough, non-articular, horseshoe-shaped, with the convexity directed downwards. It is this part of the bone which supports the nail. The superior extremity is articulated with the middle phalanx by a pulley-like surface, con- cave transversely. The ungual phalanx of the thumb is considerably larger than that of any of the other fingers. In point of structure and developement the phalanges scarcely differ from the metacarpal bones. There are two points of ossification, one for the body and inferior extremity, the other for the superior extremity. This last is late in making its appearance, not until between the third and seventh year, while the ossifica- tion of the body commences at an early period of intia-utenne life. 508 BONES OF THE HAND. Although the perfect prehensile hand is pecu- liar to man and the Quadrumana, the inferior segment of the anterior extremity will be found to possess many interesting analogies through- out the mammiferous series. On this point we refer to the articles Osseous System (Comp. Anat.) and Skeleton. JOINTS OF THE HAND. Joints of the carpus. — The bones consti- tuting each row of the carpus are firmly con- nected by strong ligaments, so that their com- bined surfaces form one extended surface adapted to the radius, or to the metacarpus, or to each other. Thus the union of the superior articular surfaces of the upper carpal row con- stitutes the convex surface that contributes to the formation of the wrist-joint, whilst the united inferior articular surfaces of the same row are adapted to the united superior surfaces of the inferior carpal row. Again, the inferior articular surfaces of this last row enter into the formation of the carpo-metacarpal joints. - The several articulations of each row are strengthened by two sets of ligaments, one on the palmar, the other on the dorsal surface of the joints, palmar and dorsal ligaments; they extend transversely from one bone to the other. The palmar ligaments are considerably stronger than the dorsal. The synovial membranes which exist in these small articulations are merely offsets from the large synovial mem- brane which is interposed between the two rows of the carpus. In the articulation between the scaphoid and lunar bones, as well as in that between the lunar and cuneiform, we observe a remarkable fibre-cartilaginous lamina interposed in the whole extent of each articulation from before backwards, although not extending over the entire articular surfaces. These lamina; are readily seen on opening the radio-carpal joint in the interval between the bones above men- tioned ; they are attached to the palmar and dorsal ligaments by their anterior and posterior extremities. When dissected out they will be found to be wedge-shaped, the thick edge being directed towards the wrist-joint, and adherent to the synovial membrane of that joint. These laminae are described by most anatomists as ligaments, under the name of interosseous liga- ments. Of their fibro-cartilaginous nature, however, I have no doubt from repeated and careful examinations; they may therefore be more correctly denominated interosseous fibro- cartilages. Feeble interosseous ligaments exist on either side of the os magnum between it and the unciform on one side, and the trapezoid on the other ; they are best seen when these bones are torn from each other. Articulation of the two rows of carpal bones to each' other. — The superior articular surfaces of the four bones composing the inferior carpal row are adapted to the inferior articular surfaces of the scaphoid, lunar, and cuneiform bones. The head of the os magnum and the superior articular surface of the unciform bone form a prominent convexity, which is received into a deep concavity formed on the ulnar side by the cuneiform bone, on the radial side by the scaphoid, and in the centre by the lunar bone ; whilst external to the projection of the os mag- num, a superficial oblong concavity receives the convexity on the inferior and outer surface of the scaphoid. Thus the line of this articulation has somewhat of the course of the roman S placed horizontally, w. That part of the arti- culation which is to the ulnar side, then, par- takes more of the nature of enarthrodia or ball and socket joint, while that to the radial side is arthrodia with almost plane surfaces. This articulation is strengthened in front by an anterior or palmar ligament which is of considerable strength and thickness. Most of the fibres of this ligament are attached inferiorly to the palmar surface of the os magnum, whence they diverge to be inserted into the scaphoid, lunar, and cuneiform bones; some few fibres extend from the trapezoid and trape- zium to the scaphoid, and from the unciform to the cuneiform. Behind we find a dorsal ligament, also strong, although much less so than the palmar. This ligament extends obliquely from the bones of the first row to those of the second, but is stronger on the ulnar than on the radial side. The extent and con- nexions of both these ligaments are best seen when the joint is opened, by cutting through the dorsal ligament to view the palmar, and vice versa. The ligaments called lateral by some anatomists are merely the continuation of the lateral ligaments of the wrist-joint ; nor do those described by Cruveilhier under the name of glenoid ligaments deserve to be separated from the anterior and posterior, of which they constitute that portion most intimately connected with the anterior and posterior notches of the hollow cavity in which the head of the os mag- num is lodged. In opening this joint in the manner already described, it will be seen how extensive is its synovial membrane. It extends some distance on the palmar and dorsal surfaces of the neck of the os magnum, and sends two processes between the bones of the first row (between the scaphoid and lunar, and the lunar and cuneiform), and three processes between those of the second row, (one on each side of the os magnum,) and one between the trapezium and trapezoid. Motions of the carpal articulations. — An examination of the dissected carpus will at once show how limited are the motions between any two of the carpal bones of each row. The movement of one row upon the other, however, is more extensive, but only in the direction of flexion and extension, the former being con- siderably greater in consequence of the less resistance of the dorsal ligaments. Solidity and strength, a power of resistance to violence which might easily occasion fracture, were the carpus one solid bone, are gained by the num- ber of small bones of which it is composed, the arthrodial form of its articulations, and the strong ligaments by which the motions of these joints are restricted. Articulation of the pisiform bone. — The pisiform bone is so little connected with the mechanism of the carpus that its articulation BONES OF THE HAND. 509 with the cuneiform bone demands a separate consideration. A plane oval surface on the posterior part of the pisiform is articulated with a corresponding one on the palmar aspect of the cuneiform, and several strong ligaments strengthen the joint. Two lateral ligaments pass from the pisiform to the cuneiform bone, the internal, which is also anterior, being of considerable strength. This bone is further connected to the unciform by strong ligament- ous fibres; and a strong bundle, which bears the same relation to the tendon of the flexor carpi ulnaris as the ligamenturn patella? does to the tendon of the rectus femoris, extends to the carpal extremity of the fifth metacarpal bone. This joint is provided with a loose synovial membrane ; its motions are those of gliding in the directions of the axis of the articular surfaces. Carpo-metacarpal joints. — These are very strong articulations, and, with the exception of the first and fifth, enjoy a very limited extent of motion. The four internal ones are nearly plamform arthrodiee, restricted on the palmar and dorsal surfaces by strong and short liga- ments ( palmar and dorsal ligaments ), the latter being much better developed. The second metacarpal bone is articulated with the trapezoid in an extremely firm manner: its palmar liga- ment extends from the extremity of the meta- carpal bone to the trapezium internal to the ridge, and covered by the tendon of the radial flexor of the wrist. There are three dorsal ligaments, an external attached to the trapezium, and an internal to the os magnum. These two ligaments are oblique in their direction ; the third or middle one is vertical and attached to the trapezoid. The third metacarpal bone is arti- culated with the os magnum : here we find three strong palmar ligaments, an external one which extends obliquely outwards to the trape- zium, an internal one which passes in front of the carpal extremity of the fourth metacarpal bone, adhering to it, and inserted into the unciform and the fifth metacarpal bone, and a middle one which passes vertically to the os magnum. This joint has two dorsal ligaments, both inserted into the os magnum. The fourth metacarpal bone is articulated with the radial portion of the inferior articular surface, and with a very small portion of the os magnum; it has a single palmar and dorsal ligament. The fifth metacarpal bone is articulated with the outer part of the inferior surface of the unciform ; this surface is convex transversely and concave from befdre backwards, while that on the metacarpal bone is convex from before backwards and concave transversely. The proper ligaments of this joint are very feeble, being merely a few fibres attached to the ante- rior and posterior surfaces of the synovial mem- brane. The joint, however, is protected in front by the prominence of the unciform pro- cess, which descends a little below the line of the articulation, and limits the forward motion of the carpal extremity of the bone ; and pos- teriorly it is strengthened by the tendon of the extensor carpi ulnaris, while its motion ulnad is restricted by the strong internal palmar liga- ment of the third metacarpal bone, which we have already described as passing from that bone to the fifth metacarpal and the unciform bones. The fifth carpo-metacarpal articulation approaches in many particulars to the first; it has a greater latitude of motion than the three immediately preceding it, and its articular sur- faces very much resemble those of the first. Besides the palmar and dorsal ligaments already described, these metarearpal bones are very firmly connected to each other by short but strong ligaments, extending transversely from one to the other on the palmar and dorsal aspects. A common synovial membrane extends throughout the four joints above described ; this synovial membrane is continuous with that between the two rows of carpal bones. The digital extremities of the four inner metacarpal bones are connected by their trans- verse ligaments situated at the palmar surface and extending from one to the other. Curpo-metucurpal joints of the thumb. — The main feature by which this articulation is dis- tinguished from the other carpo-metacarpal joints is its great mobility. It is an arthrodia, and in many particulars resembles very much the sterno-clavicular joint. The trapezium presents a surface concave from within out- wards, and convex from before backwards, that on the metacarpal bone being convex in the transverse, and concave in the antero-pos- terior direction. The ligamentous apparatus of this joint has "very much the appearance of the capsular ligament of an enarthrosis, and has indeed been described as such by many anatomists ; but on a careful examination it will be found to consist of separate bundles of ligament placed at those situations in which the greatest tendency to displacement exists in the various motions of the joint. Four principal bundles may be described : one very thick and strong, situated at the posterior and outer part of the joint, (tig. dorsale, Weitbr.) extending from the metacarpal bone to a prominent tubercle on the outer part of the dorsal surface of the trapezium; this ligament limits flexion of the joint. A second ligament is situated directly in front of the joint, (lig. palmare, Weitbr.) is inserted into the trapezium immediately internal to its prominence; extension is limited by this ligament. The third and fourth bundles (lig- laterale ext. et int. Weitbr.) are situ- ated on the radial and ulnar sides of the joint : they are less distinct as well as less strong than those last described. That on the ulnar side is considerably the stronger; it limits abduc- tion of the thumb, whilst that on the radial side limits adduction. The synovial membrane of this joint is lax ; it is perfectly distinct from the general syno- vial membrane of the other carpo-metacarpal articulations. Motions of the carpo-metacarpal joints. — In the second, third, and fourth joints the motions are limited to a very slight, and during life scarcely appreciable gliding forwards or backwards : the strong transverse ligaments, 510 ABNORMAL CONDITIONS OF THE HAND. as well as the close manner in which the carpal extremities of the metacarpal bones are im- pacted together, render lateral motion impos- sible ; in the fifth joint the forward or back- ward motion is somewhat more extensive, but this joint is equally limited with the others in lateral movement. The carpo-metacarpal joint of the thumb enjoys motion forwards, backwards, inwards, and outwards, producing the movements of flexion and extension, abduction and ad- duction. The power of opposing the thumb to any of the fingers is due to the oblique direction of flexion in this joint: the bone moves forwards and inwards, passing through a line which would be concave inwards. This is by far the most extensive motion of the thumb, and it is by an excess of this motion that the dislocation of the metacarpal bone backwards is generally occasioned. Cruveil- hier observes that the weakness of the posterior ligament favours the occurrence of this lux- ation. I cannot, however, admit the weakness of this ligament ; on the contrary, it appears to me to be the strongest of all the ligaments of this joint ; which opinion, I find, is that of the accurate Weitbrecht. The motion of adduction is, on the other hand, the most limited, in consequence of the proximity of the second metacarpal bone ; that of abduction is very extensive, and when car- ried too far may occasion luxation inwards. JOINTS OF THE FINGERS. 1. Metacarpophalangeal joints. — The first phalanges are articulated by an oval concave surface, with the rounded oblong heads of the inferior extremities of the metacarpal bones : it is remarkable that the long axis of the oval concavity of the phalanx has a transverse di- rection, while the long axis of the head of the metacarpal bone is directed from before back- wards, and consequently at right angles with the former ; whence the great extent of lateral motion enjoyed by these joints. Each of these joints is strengthened by two lateral ligaments, of considerable strength, inserted into the tubercle behind the depression on each side of the head of the metacarpal bone ; the point of insertion into the phalanx is anterior to this, and consequently the direc- tion of the lateral ligaments is downwards and forwards; as they descend, these ligaments spread out, and their anterior fibres become identified with the anterior ligament. A third ligament, the anterior ligament, or glenoid ligament of Cruveilhier, seems des- tined more to increase the extent of the pha- langeal articular concavity anteriorly, than to maintain the integrity of the joint or limit its motions. This ligament is, as Bichat expresses it, a thick and dense fibrous bundle, in shape half a ring, placed in front of the palmar sur- face of the head of the metacarpal bone, com- posed of transverse fibres which adhere in- teriorly to the anterior edge of the concavity on the phalanx, and on each side are identified with the lateral ligaments and the transverse ligaments by which the metacarpal bones are connected. If the ligaments and synovial membrane of this joint be cut all round close to their attachment to the head of the meta- carpal bone, and that bone be removed, the synovial capsule and ligaments remaining at- tached to the phalanx, a very clear idea of the relative positions of the ligaments may be formed. The synovial membrane will then appear protected on three sides by ligament ; on the radial and ulnar side by the lateral ligaments, and in front the anterior ligaments, whilst posteriorly it is unprotected save by the sheath of the extensor tendon. In the metacaipo-phalangeal articulation of the thumb two sesamoid bones, developed in the substance of the anterior ligament, protect the joint in front. 2. Phalangeal joints. — These joints are all ginglymoid, the articular surfaces being pul- ley-like ; they are provided with lateral liga- ments similar to those of the metacarpopha- langeal joints, and also with anterior ligaments similarly disposed. Motions of the joints of the fingers. — In the phalangeal joints these motions are only flexion and extension ; the former are con- siderably more extensive, and are favoured by the inferior insertion of the lateral ligaments being on a plane anterior to their superior insertion. In addition to flexion and exten- sion the metacarpophalangeal joints enjoy con- siderable lateral motion, which is due to the glenoid form of the phalangeal articular sur- face, and to the enarthrodial form which the joint derives from the extension of that arti- cular surface by the anterior ligament. (R. B. Todd.) HAND, ABNORMAL CONDITIONS OF THE. Deviations from the normal condition of the different structures which enter into the composition of the hand are very numerous, and may be classed into those which are the result of, first, accident; second, disease; third, congenital malformation. I. ABNORMAL CONDITIONS, THE RESULT OF ACCIDENT. Fractures and luxations. ■ — Simple frac- tures of the bones of the hand are seldom followed by any notable deformity ; but lux- ations of these bones require from us some attention here. Luxation of the bones of the carpus. — The bones of the carpus are united to each other so solidly, and their movements seem so limited, that, without experience, we should be dis- posed to pronounce luxation of any of these bones impossible ; nevertheless, the head of the os magnum may be dislocated from the cavity formed for it by the scaphoid and semi- lunar bones. The first range of the bones of the carpus is articulated with the bones of the second range in such a manner that slight gliding movements of flexion and extension of the hand are permitted, which augment a little the movements of flexion and extension of the hand upon the forearm, and add some- what, as Cruveilhier says, to the grace of the movements of this portion of the upper ex- ABNORMAL CONDITIONS OF THE HAND. 511 tremity. In flexion, the head of the os mag- num, which is somewhat inclined backwards, raises up the thin capsule which surrounds its articulation, and, if this movement be carried very far, the capsule and accessory fibres which support the bone posteriorly are broken, and the os magnum escapes from the cavity in which it is naturally placed ; the dislocation cannot be called complete, yet the os magnum passes somewhat the level of the posterior surface of the other bones of the carpus. The accident is more common in women than in men, no doubt because the ligaments are weaker and the bones enjoy greater motion in the former than in the latter ; the luxation backwards of the os magnum, the only one which can occur, is always the result of a forced and violent flexion of the wrist, such, for example, as a fall on the back of the hand would produce. We recognize the luxation of the os mag- num by the history of the accident, and by the deformity produced. We perceive a hard cir- cumscribed tumour which has suddenly ap- peared on the back of the hand in the situation which corresponds to the head of the bone. This tumour becomes more prominent when the hand is flexed, and diminishes when it is extended ; we can make it disappear entirely by a slight compression. This luxation causes but little inconvenience, but the head of the os magnum always remains more salient when the hand is flexed, and forms a tumour more or less marked according to the extent of the displacement. We can easily reduce this luxation by ex- tending the hand, or by exercising a slight pressure on the head of the os magnum ; but, although it is easy to make the bone resume its position in the cavity formed for it by the scaphoid and semilunar bones, it is very dif- ficult to maintain it there, and the inconve- nience and deformity resulting from the luxation are so trivial that few persons will submit with patience to the means usually recommended. Luxation of the bones of the metacarpus. — Luxation of the metacarpal bone of the thumb. The carpal head of the metacarpal bone of the thumb, notwithstanding the range of motion it enjoys, is rarely dislocated. Sir A. Cooper, in his extensive experience, has seen but one spe- cies of this accident, viz. luxation of the meta- carpal bone of the thumb upon the os trapezium, inwards. " In the cases I have seen of this accident," says Sir Astley, " the metacarpal bone has been thrown inwards between the tra- pezium and the root of the metacarpal bone of the fore-finger; it forms a protuberance towards the palm of the hand; the thumb is bent back- wards, and cannot be brought towards the little finger: considerable pain and swelling are pro- duced by this accident." Luxation of the carpal head of the meta- carpal bone of the thumb backwards. Some surgeons seem to doubt that the metacarpal bone of the thumb is capable of being dis- located in any other direction than that in- wards; but the following case is given on the highly respectable authority of the experienced Boyer. Madame De la P luxated the metacarpal bone of her left thumb backwards on the dorsum of the trapezium by falling on the external or radial border of her hand ; the luxation was at first mistaken. When Boyer saw it six months after the accident, the su- perior extremity of the metacarpal bone of the thumb formed posteriorly a very remarkable prominence on the trapezium, and this bone and the phalanges of the thumb were inclined towards the palm of the hand. On pressing posteriorly on the prominence formed by the superior extremity of the dislocated bone, it could be made to resume its natural place and the prominence disappeared ; so long as the pressure was continued, the bone retained its place and the thumb enjoyed its natural powers of flexion and extension ; but as soon as the pressure was remitted, the bone became dis- placed anew, and the movements of the thumb impossible. The lady was unwilling to sub- mit to any treatment, and the condition of the joint remained unaltered. These luxations of the metacarpal bone of the thumb, whether backwards or inwards, must be rare, as the causes which are calculated to produce them must act through the first phalanx of the thumb, which, it is manifest, will be much more dis- posed to yield than the metacarpal bone. Luxation of the phalanges of the fingers. — - The first phalanx of the thumb as well as the first phalanx of any of the fingers may be luxated backwards; the luxation forwards of the phalanx is very rare and perhaps impossible, except in the index finger and the thumb. The mutual support which the first pha- langes of the fingers afford each other laterally, and the strength of the lateral ligaments render the luxation outwards or inwards very difficult. Luxations of the first phalanx of the thumb from the metacarpal bone. The first phalanx of the thumb may be luxated forwards to the palmar surface of the metacarpal bone, but this form of luxation is very rare, while the luxation of the same phalanx on the dorsum of the metacarpal bone is the most common and important displacement of any to which the bones of the hand are liable. We shall therefore consider this accident in detail. In some persons the first phalanx of the thumb can at will be dislocated backwards, solely by the contraction of the muscles. The displacement produced by accident, however, is much more extensive than this, which may be termed the voluntary luxation. When the first phalanx of the thumb is in a state of extreme extension, accident may dislocate it on the dorsum of the metacarpal bone. The signs of the injury are so evident that mistake appears impossible; the first phalanx is thrown back as if pulled by its two extensors, and forms nearly a right angle with its metacarpal bone (fig. 226) ; the head of the latter forms a remarkable tumour at the anterior part or palmar aspect of the articulation, while a prominence behind points out the situation of the base of the first phalanx : the last or distal phalanx is (in recent cases) flexed, and it soon becomes difficult or impossible to extend it, or to flex the first phalanx. ABNORMAL CONDITIONS OF THE HAND. Fig. 226. Luxation of the first phalanx of the thumb on the hack of the metacarpal bone. Anatomical characters of this accident. Op- portunities of ascertaining by dissection the actual condition of the parts when luxation backwards of the first phalanx of the thumb has recently happened, of course do not occur, but from the dissection of old unreduced in- juries of this kind,* and from experiments on the dead subject, we are led to infer that the immediate effects of the injury are, extensive laceration of the anterior part of the synovial membrane, and of one or both the lateral liga- ments, while the posterior portion of the cap- sule remains entire ; the base of the first pha- lanx is dragged to a considerable extent upon the dorsum of the metacarpal bone, elevating with it the tendons of the extensor primi and secundi internodii pollicis; the tendon of the flexor pollicis longus is carried inwards and under the head of the metacarpal bone. As the extensor ossis metarcarpi and opponens pollicis are not attached to the first phalanx, they are little affected by the luxation, but the con- dition of the three remaining muscles which are inserted into the base of the first phalanx requires consideration. These short muscles are the abductor pollicis, the flexor pollicis brevis, and the adductor pollicis. When the dislocation backwards of the first phalanx of the thumb has occurred, the large head of the metacarpal bone is at the same time thrown inwards towards the palm, and having forced its way between the two origins of the flexor pollicis brevis, the shaft of this bone, which is comparatively much narrower than the head, becomes tightly embraced by the two fleshy columns of the muscle. This is a state of things which should be taken into account when the obstacles to the reduction of this dislocation are considered, nor should it be forgotten that the direction and relative position of the points of attachment of all the muscles concerned must be altogether changed when the complete luxation has occurred ; their origins and insertions are more than na- turally approximated, and the line of direction of their action is thrown much behind the * See London Medical Gazette for Oct. 14, 1837, J. A. Lawrie, Glasgow. longitudinal axis of the metacarpal bone ; the tendons of the extensor primi and secundi internodii, and of the flexor pollicis longus are of course carried by the dislocated bone behind then- usual line of action; hence the action of all these muscles, after the luxation has oc- curred, becomes materially altered, their con- traction will no longer be resisted by the lateral and capsular ligaments, and the bone will be drawn upwards and backwards by them, a considerable distance on the dorsum of the metacarpal bone (Jig. 226). The flexors have their direction so altered and so thrown behind the longitudiua) axis, of the metacarpal bone of the thumb, that they now no longer act as flexors of the first phalanx to approxi- mate it to the palm ; on the contrary, they now have become extensors of the dislocated pha- lanx, and tend much by their contraction to increase the deformity.'* This dislocation is difficult to reduce, par- ticularly if the nature of the accident have not been speedily recognized. Various causes have been assigned for the opposition to the return of the bone; some think with the late Mi. Hey of Leeds, that a transverse section of the head of the metacarpal bone presents in its outline somewhat of a cuneiform figure ; and that, in consequence of the narrowest part of the wedge being thus placed anteriorly, it can easily under the influence of accident glide towards the palm by passing between the lateral ligaments which remain unbroken, and resist all return of the bone backwards to its original situation. Others imagine that the interposition of the anterior ligament and sesamoid bone attached to it between the arti- cular surfaces constitutes the principal ob- stacles to the reduction of this luxation. Again it has been asserted that the tendon of the flexor longus pollicis has been twisted spirally under the metacarpal bone, while some with more appearance of truth have supposed that the muscles are the principal sources of re- sistance. The learned author of the First Lines of Surgery has expressed his opinion that the return of the dislocated phalanx to its place is opposed by a combination of causes, viz. — the cuneiform shape of the bone and the re- sistance of the lateral ligaments, as suggested by Hey, the force of the muscles, and, lastly, he adds, because the surface for the applica- tion of the extending means is very limited. To most of these observations we have reason to object, particularly to the last, because we believe that all the force which it is justifiable to use may be easily applied ; and we should * In the experiments made by my colleaeue Mr. Mayne and myself on the dead subject, when we forcibly dislocated the first phalanx backwards, we found the anterior part of the synovial membrane and the external lateral ligament torn across ; the first phalanx was placed as in fig. 226. We found the head of the metacarpal bone driven between the two heads of the flexor pollicis brevis in such a way, that the external head of the muscle was placed upon the outside of the shaft of the bone in com- pany with the abductor pollicis, while the internal was situated at the inside of it, along with the ad- ductor and long flexor tendon. ABNORMAL CONDITIONS OF THE HAND. 513 ever keep in mind a case given on the authority of Mr. Hey, who informs us that the celebiated Mr. Bloomfieid reported to his class of pupils at St. George's Hospital, London, that he knew a surgeon increase the force of extension to such a degree in attempting reduction of this dislocation, that he tore oft' the thumb at the second joint. The idea that a transverse section of the head of the metacarpal bone presents an outline of a cuneiform figure with the narrowest part of the wedge towards the palm, or forwards, was first advanced by Mr. Hey, and has subsequently been adopted with too little reflection by many writers : for our part we do not think that the head of the metacarpal bone does present this form assigned to it by Hey. But even al- though it be conceded that it has occasionally a form which would answer to the description given by Mr. Hey, and that its cuneiform figure would facilitate its gliding between the lateral ligaments and forbid its return, surely such an obstacle to the return of the bone would suppose a state of integrity of both lateral ligaments. In our experiments on the dead subject, we found one of these lateral ligaments invariably torn whenever a complete luxation was effected ; but with the theory of Hey, which seems to us quite unsupported by the normal anatomy of the bone or the anatomy of the accident, how can we reconcile the observation, that when the first phalanx of the thumb is dislocated to the palmar instead of the dorsal aspect of the metacarpal bone, equal difficulty of reducing the luxation has been experienced by very eminent surgeons ' For example, Velpeau says, " we have seen but once the first phalanx of the thumb pass in front of the first metacarpal bone. The sub- ject of this accident was a woman aged forty- five years; the bone had been out for three days, there was no inflammation." I thought, says Velpeau, " that it was owing to some want of skill in myself that I could not succeed in reducing the luxation ; but M. Professor liou- gon also made fruitless efforts to effect it; finally, M. Roux, with his well-known address and ingenuity, was not more successful, and the bone remained ever afterwards unre- duced."* Upon the whole it would appear to us that in the case of the dislocation of the first pha- lanx of the thumb on the dorsum of the meta- carpal bone, the cause of the difficulty we ex- perience in reducing it will not be found either in the mechanical resistance of the lateral liga- ments or in the interposition of muscular or fibrous parts between the extremities of the dislocated bones, but that, whether the luxa- tion be the common one backwards or the more unusual one forwards, thevital contraction of numerous muscles on a small and yielding bone (whose ligaments have been lacerated) will be the principal opposing force we have to contend with. Most of these muscles will be found to be favourably circumstanced for the * Velpeau, Traitc d'Anatomie des Regions, torn. i. p. 475, edit. 1825. VOL. I / . opposition, for they are either inserted into or attached very close to the bones of the first phalanx of the thumb: they are six in number; some of them are of considerable length, and the aggregate force of both long and short muscles constitutes a very powerful means of maintaining displaced the first phalanx of the thumb ; nor should it be forgotten, in estimat- ing their force, that the very large supply of blood- vessels and nerves which these muscles receive, must add much more to the energy of their contraction than the size and number of their composing fibres would lead us to suppose. If such a view of the abnormal condition of the different structures which compose this articulation be correct, we should derive from it the important practical precept, that when we have one of those difficult cases to contend with, our first effort should be to reduce, as much as practicable, the irritability and vital force of the muscles which act on the dis- located bone before any of our mechanical appliances be resorted to. When the general system of the patient has been under the de- pressing influence of the usual means, viz. tartanzed antimony, &c, and under these fa- vourable circumstances the surgeon has with patience and perseverance used all the force that he deems expedient or justifiable, and has not succeeded in replacing the bone, our expe- rience would induce us to recommend that in such a case no further measures should be had recourse to. We have, in the museum of the Richmond Hospital, a cast of the hand of a man who had suffered this luxation sixteen years before the cast was taken. The history he gave the writer was briefly that he consulted an eminent surgeon, who used all the means in his power to reduce the dislocation, but could not succeed; that the surgeon then proposed to the man an operation which he explained, and which from the patient's description of it we may conclude consisted in laying bare the head of the metacarpal bone and removing it, as had been about that time recommended by Mr. Evans, of Kettley near Wellington ; the man, however, refused to consent to the pro- posal, and had good reason to be content with his own determination, as he can now oppose the point of the thumb to the other fingers, and can follow his business, which is that of a plas- terer, with very little inconvenience, affording us a proof that the advice given by Sir A. Cooper relative to irreducible dislocations of the metacarpal bone, may be well extended to the common dislocation backwards of the first phalanx, viz. " that if the bone cannot be re- duced by simple extension, it is best to leave the case to that degree of recovery which nature will in time produce, rather than divide the muscles or run any risk of injuring the nerves or the bloodvessels." The first phalanges of any of the other fin- gers may be luxated backwards. The little finger appears to us, after the thumb, the most liable to this accident ; it is sometimes difficult to reduce. Mr. Romer, a pupil of the Rich- mond Hospital, lately brought to the writer a patient who was the subject of luxation of the 2 M 514 ABNORMAL CONDITIONS OF THE HAND. first phalanx of the little finger on the back of its metacarpal bone. This patient was a female about thirty-five years of age ; the bone had been only a few hours luxated, and some inef- fectual attempts had been previously made to reduce it. The reduction was effected with some little difficulty by at first increasing the extension, and then by forcibly flexing the last phalanx. In this case the long extensor tendon of the little finger was displaced from its sheath and groove, and lay on the ulnar side of the metacarpal bone and luxated phalanx, and never afterwards could be maintained in its proper place. This accident is very easily re- cognized, yet it has been occasionally left un- reduced. It has been stated already that luxation of the first phalanx of the thumb forwards may occasionally happen, and we have also good authority for supposing that a similar luxation may occur to the phalanx of the index finger. These accidents, however, are very rare ; the middle, ring, and little fingers have never been seen thus displaced ; indeed, Boyer seems to think such an accident in these last, impossible from the nature of their articulation with their metacarpal bones. Luxation of the second, and third or distal phalanges. — The articulations of these pha- langes being only covered by the skin and the tendons of the flexor and extensor muscles, their luxations are also very easily recognized. In the luxation backwards, the only one which we have had occasion to observe, the luxated phalanx is turned to the side of extension, and forms with the phalanx above it an angle more or less open, \\hen it is the second phalanx which is luxated, the third is flexed by the elongation of the tendon of the deep flexor, and it is impossible to extend it or flex the second. The reduction of these luxations is generally easy if time be not allowed to elapse between the occurrence of the luxation and the period of attempting its reduction. II. DISEASED CONDITIONS. Caries and necrosis occasionally affect the bones of the hand, but the complete descrip- tions of these diseases, which have been else- where given in this work,* render superfluous here any special observations on these morbid actions when they manifest themselves in the region of the hand. The bones of the meta- carpus and phalanges are very frequently de- formed by a disease which (although it cannot be said to be exclusively observed in these bones) produces on the hand and fingers ap- pearances too remarkable to be left unnoticed in this place. The disease which we wish to describe as we have seen it in the bones of the hand would be by some designated as exostosis,! by others as benign osteo-sarcoma, and others J would be * See Bone, morbid anatomy. f See Scarpa, De Anatomia et Pathologia ossinm, cum tabulis aeneis, tab. \i.fig. 1, Exostosis ossiuin plerorumque manus dexterae. X Boyer, Maladies Chirurgicales, vol. iii. p. 579. disposed to preserve the somewhat objection- able but ancient name of spina ventosa. The metacarpal bones and the phalanges of the fingers are the usual seat of this disease, and in general many of them are simulta- neously engaged in it; the shafts of the affected bones are usually swelled out by the disease into tumours somewhat of a globular form, the articular extremities of the bones remaining perfectly free. It is by no means unusual to see the first and second phalanx of a finger forming two distinct globular swellings, while the last or distal phalanx is perfectly free from enlargement. It has been already mentioned that these tumours, when viewed externally, seem to have a spheroidal form ; but when the integuments of the bony shell which incloses the tumours are removed, we discover on their palmar as- pects the flexor tendons buried in deep grooves. This is of course best seen when the disease has existed long, and the tumours have attained a considerable size. If we have an opportunity of examining ana- tomically the phalanges while the disease is yet in its early stage, we shall find reason to conclude that the morbid process had com- menced deep in the interior of the bone, and that the tumour proceeding outwardly presented itself first on that aspect of the phalanx, or me- tacarpal bone, where there was the least resist- ance opposed to it ; hence we usually notice these tumours, when small, shewing themselves most on the dorsal aspect of these bones. As the disease increases they swell out laterally, and the whole circumference of the phalanx would be equally expanded were it not for the support given on the side of flexion by the flexor tendons and their strong fibrous sheaths. The integuments of these tumours preserve their natural sensibility, and are at first freely move- able over them ; but as the swellings gradually increase and undergo a species of softening in certain points, the integuments become adhe- rent at these points, and circular openings are formed in them which correspond to similar circular apertures in the shell of the bone, and through which the bony cysts discharge their contents ; these swellings of the bones of the hand, as far as we know, never degenerate into any disease of a malignant nature; but when they attain a considerable size, and are exca- vated by these cysts, and have large fistulous orifices, the irritation they produce and the discharge cause some febrile excitement of the constitution, and amputation may become ne- cessary. The following very remarkable case clearly proves the non-malignant nature of this disease; the history of it will serve well to illus- trate the natural progress of this form of dis- sease in the hand. A countryman of rather a delicate appear- ance, a air, as has been asserted. The liquid called the liquid of Cotugno, or by De Blainville peri- lymph, must not be confounded with ano- ther which is contained in the interior of the membraneous, labyrinth. Dominico Cotugno,^ though not actually the discoverer of this liquid, yet took a more correct view of it than his pre- decessors in this branch of anatomical research, Valsalva,! Vieussens,§ Cassebohm,|| and Mor- gagni.H He in fact recognised in it a substance fulfilling some office in the exercise of hearing, a view of the matter which was admitted by I Jailer, and put beyond doubt by Ph. Fr. Meckel,** and since their time recognised by all physiologists. The perilymph occupies, in the vestibule and semicircular canals, all the space not taken up by the membraneous labyrinth. The cochlea contains nothing but it ; and as all the cavi- * Comment. Bonon. torn. vii. Anatomia Surdi Nati. p. 422. t De Aqueductibus Auris Humans Anatomica Dissfrtatio, s. xxix.-xxxi. Neapoli, 1760. { De Aure Humana Tractatus, &c, cap. iii. s. 17, p. 79. Trajecti ad Rhenum, 1707. § Traite Nouveau de la Structure de l'oreille, p. 75. Toulouse, 1714. || Tractatus Quintus Anatomicus de Aure Hu- mana, &c, pp. 20-21. De Labyrintho. Hals Magd. 1735. 1; Epist. Anatom. xii. s. 64, p. 469. Venetiis 1740. *• Dissertatio Anatomico-Physiologica de Laby- rinthi Auris Cont-ntis, &c. Argentorati, 1777, s. 8. ties of the osseous labyrinth communicate, it is the same humour in each. In all fishes, except thecartilaginous with fixed gills, the labyrinthic cavity is very imperfect, being in many of them open towards the cranial cavity, or at the most separated from it only by a membraneous partition, as in the cod ; hence the encephalic liquid in some of them is not dis- tinct from the perilymph whose function it must perforin. In thecartilaginous fishes with fixed gills, on the contrary, the labyrinthic cavity is completely separated from the cranial ; therefore in them we meet with perilymph distinct from the encephalic liquid, and that, too, in pretty large quantity. In birds the perilymph is in much less quan- tity than in the mammifera, in proportion to the size of the membraneous labyrinth. In rep- tiles the quantity of perilymph is still less. Cotugno and Meckel supposed that the aqueducts were a sort of diverticula, or cavi- ties which served to let off the superabundant perilymph, when necessary, during the act of hearing. This opinion is, however, now-a-days very much questioned, and several anatomists, Brugnone, Ribes, Breschet, &c, refuse to those aqueducts the uses which Cotugno assigned them, and consider them merely as canals des- tined for the passage of bloodvessels. Although they may be insignificant in a physiological point of view, still, if the description I have given of them be correct, they must be consi- dered as something more than mere canals for the transmission of vessels. The constancy of the aqueducts, moreover, is another argument against their being mere vascular canals. Breschet,* and in Hildebrandt's Anatomieby Weberf the same idea is concisely expressed, explains the mode of formation of the aque- ducts by supposing that at first the labyrinthic cavity is nothing but a sac formed by a prolon- gation of the dura mater in the same way as the tunica vaginalis is of the peritoneum ; that as development proceeds, the tube of communi- cation between the labyrinthic sac of the dura mater and general cavity of the dura mater is gradually contracted and elongated ; and that as ossification extends, the tube becomes sur- rounded by osseous substance, and presents itself under the appearance of an aqueduct. "This view," says Breschet, "is rendered probable, for in many fishes the labyrinthic cavity forms one with that of the cranium, and if, in these animals, a prolongation of the walls of the cranium tended to separate the brain from the ear, there would result a small canal establishing a communication between the two cavities, and this canal would be nothing but an aqueduct." According to this view, the lining membrane of the labyrinthic cavity may be considered as a continuation of the arachnoideal layer of the dura mater, perhaps of the dura mater also. 2. The membraneous labyrinth, ( labyrinthus membranaceus. Fr. Lubyrinthe membraneux. Germ. Das hdutige Labyrinth.) — Within the * Op. cit. t Hand iv. p. 32. ORGAN OF HEARING. 537 osseous labyrinth is contained an extremely delicate and complicated membiano - ner- vous apparatus, called membraneous laby- rinth, first properly described by Scarpa.* It does not extend into all the compartments of the osseous labyrinth, but only occupies the vestibule and semicircular canals. The coch- lea, as has been said, contains in its cavity nothing but perilymph. The vestibular part of the membraneous labyrinth, and of that perhaps one of the pouches only, is all that is really fundamental in the structure of an organ of hearing. In the Crustacea and Cephalopodous Mollusca in which the organ of hearing exists in its sim- plest form, and even in the Cyclostomatous fishes there is nothing but a small pouch con- taining a little liquid and a lapilliform body. Much smaller than the cavities which con- tain it, the membraneous labyrinth is sus- pended as it were in the perilymph. It does not appear to adhere to the walls of the laby- rinthic cavity except at the points where it re- ceives nervous filaments. The component parts of the membraneous labyrinth are: — 1. The common sinus. 2. The membrane- ous ampullae and semicircular tubes. 3. The saccule. Fig. 238. A magnified representation of the left osseous laby- rinth laid open to show the membraneous labyrinth in its situation. ( From Breschet.) a. membraneous ampulla of the ampullary sinus of tlie anterior semicircular canal ; b. membrane- ous ampulla of the ampullary sinus of the external semicircular canal ; c. membraneous ampulla of the ampullary sinus of the posterior semicircular canal; d. anterior memhraneous semicircular tube; e. external membraneous semicircular tube ; f. posterior membraneous semicircular tube : g. coin- * De auditu ct olfactu. mon membraneous tube resulting from the junction of the tubes d and f ; h. the place where the ex- ternal membraneous semicircular tube opens into the common sinus ; i i. common sinus filling a great part of the vestibule ; k. a small mass of calcareous powder shining through its walls ; I I. saccule, also containing, m. another mass of cal- careous powder ; n a nervous fasciculus, furnishing, 0. an expansion to the anterior membraneous am- pulla ; p. another to the ampulla of the external tube, and q. a third to the common sinus ; r. ner- vous fasciculus to the saccule ; another fasciculus of nervous filaments, not letteted, is seen going to the ampulla of the posterior membraneous semi- circular tube ; s s. spiral lamina ; s. the termin- ation of the spiral lamina in the hamulus ; t. com- mencement of the scala tympani near the fenestra rotunda, which is here no longer seen ; u. com- mencement of the scala vestibuli ; x. extremity of the axis around which the termination of the spiral lamina turns ; y y. a bristle engaged in the heli- cotrema ; x. place where the summit of the axis is continued into the wall of the osseous labyrinth ; www, membraneous portion of the spiral lamina, particularly broad in the last turn, (lettered u u u in the figure instead of w w w) ; ***** * spaces between the walls of the labyrinthic cavity and membraneous labyrinth occupied by the peri- lymph. Fig. 239. The left membraneous labyrinth isolated together with the nerves. Magnified. ( From Breschet. J a. ampulla of the anterior semicircular tube ; b. ampulla of the horizontal semicircular tube ; c. ampulla of the posterior semicircular tube ; d. common tube ; e. mass of calcareous particles lying in the common sinus; f. the saccule con- taining also a mass of calcareous particles ; k. portio dura of the seventh pair ; m. nervous fila- ments to the ampulla of the anterior semicircular tube ; n. filaments to the ampulla of the hori- zontal semicircular tube; filaments are also seen going to the ampulla of the posterior semicircular tube, not lettered ; o. filaments to the common sinus ; q. filaments to the saccule ; r. cochlear nerve. The common sinus, membraneous ampulla, and membraneous semicircular tubes. — These constitute but one apparatus which is just the counterpart of the vestibule, ampullary sinuses, and semicircular canals of the osseous laby- rinth; the semicircular tubes opening into the ampullae and common sinus in the same way 538 ORGAN OF HEARING. that the semicircular canals open into the am- pullary dilatations and the vestibule. The common sinus is an elongated, laterally compressed pouch, and lies in the posterior part of the vestibule. It extends into the upper horn to join the ampulla of the superior vertical, and of the horizontal semicircular tubes ; and into the posterior and lower horn, to join the ampulla of the posterior semicircular tube, and to receive the tubulus communis and cylindrical extremity of the horizontal tube, as they emerge from their respective canals. Its upper end, which is larger than its lower, lies in the hemi-elliptical cavity, to the bottom of which it is fixed by nervous filaments. The membraneous tubes are only about a third part of the calibre of the semicircular canals in which they are contained. Like the latter they are distinguished by the epithets, superior vertical, posterior vertical, and hori- zontal. Each membraneous semicircular tube opens at one of its extremities, like its cor- responding osseous canal, into an oval dila- tation called ampulla, which on its part com- municates with the common sinus. As the vertical semicircular canals unite at one of their extremities to form the common canal, so their corresponding membraneous tubes also unite to form a common tube, tubulus communis, which occupies the common canal. At the place where the nervous filaments enter the common sinus, its wall presents a much more considerable thickness and consist- ence than elsewhere. According to Steifensand,* who has ex- amined the structure of the ampullae very carefully, each ampulla presents a very much arched surface, superficies convexa, and op- posite to this a concave or indented surface, superficies concava s. injiexa, which receives the nervous filaments. Where the nerve enters there is a transverse depression, sulcus trans- versa, by which this surface is divided into two parts. This transverse depression on the outside produces in the interior a fold of the membrane composing the wall of the ampulla, and through which the nerve enters. This fold forms a transverse septum, septum trans- versum, which divides the interior of the am- pulla into two parts; one of which, the sinus part, communicates by the osteum sinus with the common sinus, and the other, the tube part, by the osteum tubuli with the membraneous tube. Saccule, sacculus rotundus. This is a round membraneous bag, smaller than the common sinus in front of which it lies in the hemisphe- rical depression of the vestibule. It is firmly fixed in its place by nervous filaments which proceed to it through the apertures observed in the bottom of the hemispherical depression. As has been mentioned in regard to the com- mon sinus, the wall of the saccule presents an increase of thickness and consistence at the place where the nervous filaments enter it. * Miiller's Archiv. fiir Anat. Physiol, und wis- senschaftl. Medecin. 1835. Heft. II. pp. 173, 174. Small in the Mammifera, the saccule is very distinct and large in fishes. The common sinus and saccule adhere to each other, but whether their cavities com- municate has not been determined. They are fixed, as has been said, to the inner wall of the vestibule, by the nervous filaments which they receive through the apertures with which that part is perforated. Towards the outer wall they are nowhere in contact with the base of the stapes, the perilymph intervening. This circumstance, first distinctly pointed out by Scarpa,* and particularly insisted on by Bre- schet, shows that it is only by the intermedium of the perilymph that the movements of the stapes can have any impression on the nervous expansions of the membraneous labyrinth. The common sinus, ampullae, semicircular tubes, and saccule are composed of a firm trans- parent membraneous coat,within which is a ner- vous expansion, and outside which is a cellulo- vascular layer, in some places tinged black or brown. Of the nervous expansion we shall speak under the head of the auditory nerves. In the sheep, hare, rabbit, &c. the walls of the membraneous labyrinth present patches of black pigment, a circumstance noticed by Scarpa,! Comparetti,J and Breschet.§ Before I knew of the observations of these anatomists I had myself observed the fact. I was not, however, led to the discovery of it by accident; but, being engaged in researches on the pig- ment of the eye, and considering the analogy which the organs of sense bear to each other in their general anatomical structure, I was curious to know whether pigment did not exist also in the ear. Examination proved to me that it did ; for I found, as Scarpa and Com- paretti had previously noticed, pigment de- posited in the form of small black spots in the membraneous parts of the labyrinth in dif- ferent Mammifera. In some I have found a distinct cell ulo- vascular layer of a black or brown colour forming the outer surface of the membraneous labyrinth. And, contrary to what Breschet asserts, I have found pigment in the membraneous labyrinth of the human ear also. It appears, especially on the am- pullae, under the form of a slight but perfectly distinct brown tinge, similar to what is seen around the ciliary processes in the eyes of Albinos. Semicircular tubes are found in all the Ver- tebrate animals, with the single exception of the Cyclostomata. When they do exist there are never more nor less than three. The common sinus, ampullae, semicircular tubes, and saccule contain a limpid humour. Suspended in this humour there is found in the common sinus and also in the saccule a small mass of calcareous powder. The liquid of the membraneous labyrinth, * Anatomicae disquisitiones de Auditu et Olfactu, s. xvi. p. 55. t Op. cit. s. iv. p. 49. i Observat. Anatom. de aure interna coroparat. p. xxxii. Praefat. § Op. Cit. ORGAN OF HEARING. 539 or endolymph or vitreous humour (if' the ear. ( Aquula labyrinthi membranacei. Humor vitreus auris. Fr. Vitrine auditive. Germ. Wasser des hdutigen Labyrinths. Die Glasf'euchtigkeit des Ohres. — This humour, first distinctly pointed out by Scarpa, fills exactly all the cavities of the membrane- ous labyrinth, — that is to say, in the human ear, the common sinus, ampullae, the semi- circular tubes, and saccule. Like the peri- lymph, it is almost as limpid as water. In the endolymph there are, as has been said, always found suspended calcareous concre- tions. The endolymph is in birds as limpid as in the Mammifera; but in reptiles it is in general more dense than water and a little viscid. It is viscid in all fishes, but especially so in the Chondropterygenous, in which it often presents itself in the form of jelly. It is also very decidedly viscid in the Cephalopodous Mollusca. The masses of calcareous matter contained within the membraneous labyrinth. — In the ear- bulb of all animals which possess one, there are found small masses of a chalky nature ; in some solid, in others pulverulent. Solid concretions are found in the osseous fishes, and in the Chondropterygenous fishes with free gills, such as the sturgeon. The chalky mat- ter is in a pulverulent state in Mammifera, birds, reptiles, and in Chondropterygenous fishes with fixed gills. In the Batrachian rep- tiles and Cephalopodous Mollusca, the cal- careous matter appears rather under a concrete form. These calcareous masses are best known in osseous fishes, in which they are hard but brittle bodies of a determinate shape. In those animals, indeed, they have been erro- neously considered as analogous to the tym- panic ossicles of the higher V'ertebrata. MM. Breschet* and Huschkef have lately called particular attention to the subject, and have described masses of calcareous matter in the ear of reptiles, birds, and Mammifera. Scarpa and Comparetti had observed them in the human ear, without, however, detecting their nature. But they had been unequivocally noticed before by De Blainville ; % and pre- viously to the first publication of Breschet's papers on the ear in the Annates des Sciences Maturelles, I had also studied them throughout the animal series. Breschet has proposed for the solid masses the name of otolithi, from ovs, auris, and AiGo?, lapis; and for the pulverulent ones that of otoconia, from ot;;, and xon;, pulvis. Otoconia has been translated into German by Lincke § Ohrsand. Huschke calls the pulverulent matter * Lib. cit. t Isis, 1834. Heft. 1. p. 107. 1833. Heft. vii. p. 676. \ De l'Organization des Animauxou Principes d'Anatomie comparee, torn. i. p. 451-458. Paris, 1822. Also, Cours ile Physiologie generale et com- paree, &c. Paris, 1829. xii Lecon. p. 399. § Das Gehororgan, &c. s. 176. p. 203. Leipzic. 1837. V h ear-crystals, Ohrkrystalle. Krause, ear-chalk, Ohrkalk. In the ear of man and the Mammifera in general there are two masses of calcareous matter ; one in the common sinus and the other in the saccule. According to Huschke and Barruel they are composed of mucus, carbonate and phosphate of lime, and some animal matter. They are said to be more dis- tinct in the foetus than in the adult. From my own observations I should say that they exist in the human adult as distinctly as in the fcetus. Concretions are never found in the ampulla; or semicircular canals, either in man or any of the lower animals. Examined in man and the Mammifera the concretions are suspended in the endolymph, and correspond to the points of the common sinus and saccule where the nervous filaments are implanted. The grains composing the calcareous mass are held together by a soft mucous tissue. Huschke describes the grains as crystalline, small six-sided columns, pointed at the ends with three surfaces. They appear to me, under the microscope, to have an oval form, more or less elongated, in man and the mammifera, passing into a spindle shape in birds and rep- tiles, and, though transparent, they do not pre- sent any very decided crystalline form. The particles of chalk examined through the micro- scope have a somewhat similar appearance, but much smaller. The grains of the ear are of different sizes. Of a mass which I removed from the ear of a middle-aged man, the greatest number had their longest diameter equal to that of the globules of the human blood, that is, about the three-thousandth part of an inch. There is found in the cochlea of birds a mass of calcareous matter. Breschet says he has found, in cochleae of the human fcetus, which had been dried but not macerated, small masses of cretaceous matter deposited near the summit of the cochlea; and Huschke* once found, in the fluid of the cochlea of a child, a collection of microscopical crystals. Cruveilhier* asks, do the small masses of cretaceous matter, found in the ear of man and the mammifera, fulfil the same function as the stones in the ear of fishes ? or must they be considered as a remains only of a part import- ant in other animals ? Breschet says, " the otolithes and otoconies have, for their use, to communicate to the nervous extremities a more vivid and energetic impression than a simple liquid like the endolymph could do; for the vibrations of a solid body are much more sen- sible for their force and degree of intensity than those of a liquid body." However this may be, it appears that the development of these con- cretions coincides, in some degree, with the medium inhabited by the animal ; thus, they are stony in most animals living in water, and pulverulent in such as exist in air. The auditory or acoustic nerve. — Nervus au- * Loc. cit. t Anatomie descriptive, tome iii. p. 524. 4 ORGAN OF HEARING. 540 ditorius s. ucusticus. — Fr. Nerf audit if 'ou acous- tique. — Germ. Der Gehornerv. — The internal auditory meatus of the temporal bone appears to enrl in a cul-de-sac ; but, examined more closely, the bottom is found divided into two unequal-sized depressions, an upper and a lower, by a crest, which extends backwards from the anterior and outer wall of the meatus. The upper depression, which is the smaller, is subdivided into two, an anterior and a posterior, by a small vertical pillar. The anterior leads into the aqueduct of Fallopius, and gives pas- sage to the facial nerve. The posterior is almost funnel-shaped, and presents two or three pretty large apertures, and several smaller and less distinct ones. These are the mouths of small canals which lead into the vestibule, and their terminating orifices produce that sieve-like ap- pearance in the pyramidal elevation between the hemi-elliptical and hemispherical depres- sions, and which extends towards the ampullary dilatations in the superior horn of the vestibule. The lower and larger depression presents two subdivisions. The anterior and larger corres- ponds to the base of the axis of the cochlea ; it presents a spiral groove or tract — tractus spi- ralisJbraminutentus, answering to the turns of the cochlea, and perforated like a sieve by nu- merous apertures, which diminish in size towards the centre, where there is one opening larger than the rest. The posterior subdivision of the lower depiession is a small superficial fossa, perforated by two or three larger, and a great number of smaller apertures, which open into the hemispherical depression of the vestibule, producing the sieve-like spot already mentioned as existing there. Below this superficial fossa there is a pretty large hole, leading into a canal in the posterior wall of the vestibule, which opens by several small orifices, forming the sieve-like spot within the mouth of the ampullary dilatation of the lower extremity of the posterior vertical semicircular canal. The different minute apertures we have de- scribed give passage to the fibrils of the audi- tory nerve. The internal auditory meatus is lined by dura mater. The facial nerve enters the internal auditory meatus along with the auditory nerve. At the bottom of the meatus there is a communication between the two nerves, which was first pointed out by Mr. Sw?n. Separating from the audi- tory nerve, the facial leaves the internal meatus, by entering the aqueduct of Fallopius. From its origin to about where it enters the internal auditory meatus, the auditory nerve presents most distinctly the delicate-walled tubular structure of brain. Within the mea- tus it assumes the ordinary thick-walled cylin- drical tubular structure of nerves; a circum- stance overlooked by Ehrenberg, when he ad- duced, as a peculiarity of the special nerves of sense, that they presented throughout their course the so-called varicose tubular structure. The auditory nerve divides into two branches — an anterior, or cochlear ; and a posterior, or vestibular branch, — which externally remain united together as far as the bottom of the meatus. The former is whiter, and has its fila- ments more compactly bound together than the latter. Examined under the microscope, the cylindrical tubules of the cochlear nerve ap- peared to me to be larger than those of the vestibular, and to contain, or at least to give out, a greater quantity of nervous medulla. The anterior branch, or cochlear nerve, ner- vus cochlea, is something like a flat tape rolled on itself longways. It proceeds forwards to that depression at the bottom of the internal auditory meatus, already described as corres- ponding to the base of the axis. Here it resolves itself into a number of fine filaments, which enter the apertures in the spiral tract of holes. Traversing the small bony canals leading from those apertures into the substance of the axis, they enter the bony spiral lamina according as their turn comes, by bending nearly at a right angle, and spread out upon it. The first fila- ments given oft' are the largest, the rest gradually diminish in size. The first turn of the spiral lamina is supplied by those which enter the first turn of the spiral tract of holes ; the second turn receives the filaments which traverse the bony canals, into which the fine apertures of the second turn of the spiral tract lead ; and the last half turn is supplied by that large bundle of filaments ter- minating the nerve, and which, entering the axis by the large opening in the centre of the spiral tract, emerges at its summit. The vestibular nerve, nervus vestibuli, which presents a small gangliform enlargement, di- vides into three branches. The uppermost, which is the largest, lies in the depression be- hind the entrance to the aqueduct of Fallopius. Its filaments having penetrated the vestibule by the small apertures of the canals already mentioned in the pyramidal elevation, arrange themselves into three fasciculi; of which one is distributed to the common sinus, and the other two to the ampulla; belonging to the superior vertical and to the horizontal semicircular tube. The fibrils of the next branch enter the ves- tibule by the apertures at the bottom of the hemispherical depression, and terminate in the saccule. The third, or lowest branch, which is the smallest, enters that canal described in the pos- terior wall of the vestibule, and which opens by a sieve-like spot within the ampullary dila- tation of the posterior semicircular canal. Its fibrils are distributed to the ampulla of the posterior semicircular tube. Such is the description of the divisions of the auditory nerve as given by most authors, and as it has appeared to me in the examina- tions I have made. Krause and Breschet, how- ever, describe the mode of division ditfeiently. The former says the nerve of the saccule comes off from the cochlear nerve ; the latter, that the cochlear nerve (which he calls the posterior fasciculus of the auditory nerve) gives off both the saccular nerve and the filaments to the pos- terior ampulla. I have not at present an oppor- tunity to repeat my examination of the parts, ORGAN OF HEARING. 541 to enable me to say positively which description is the most correct.* The nervous fibrils of the cochlea, according to Breschet, traverse the osseous zone of the spiral lamina under the form of cylindrical bundles, which, in the middle zone, become flat, and anastomose by loops. These loops are intermingled with small osseous particles. Near the outer margin of the middle zone, the neurilemma leaves the nervous filaments, and goes to form the framework of the membraneous zone, whilst small globules are seen irregularly disseminated around the convexity of the loops which the filaments form by their anastomoses. All this, however, is not so unequivocally dis- tinct as Breschet pretends. What I have been able to see in regard to the termination of the nerves on the spiral lamina, is simply this : — The tubular structure of the nervous filaments ceases, among grains of nervous matter ar- ranged into a sort of expansion. There is nothing that can be called a termination in loops. Mueller thinks the nervous fibrils do not form loops in the bird's cochlea. " But," says Mueller, " it is of no consequence, in the present state of the physiology of the nerves, whether the nerves of sensation form at their terminations loops or not." Treviranusf found a papillary termination of the nervous filaments, not only in the retina, but also in the nervous expansions of the ear and nose. The papillae of the auditory nerve he saw on the spiral lamina of the cochlea in young mice. The osseous part is entirely covered with filamentous papillae, lying close together. Gottsche also found the ends of the nerves of the cochlea in hares and rabbits club- shaped. In the hare, the nervous cylinders ter- minate in an oval knob. The following figures from Breschet illustrate his views of the mode of termination of the nervous filaments of the cochlea. Fig. 240. The cochlear nerve entirely isolated. ( Magnified. ) a, a, a. trunk of the nerve -, 6, b, b. its filaments in the osseous zone of the spiral lamina ; c, c, c. the anastomoses in the middle zone. * In the sheep I have found the division of the auditory nerve corresponding to the first description given above. t Beitrage, &c. lsten Bandes 2tes Heft. Neue Untersuchungen ueber die organischen Elemente der thierischen Koerper, p. 55. Bremen, 1835. Fig. 24t. A, a small piece of the spiral lamina, natural size, as seen from the surface corresponding to the scala vestibuli. B, the same part considerably magnified to show the globular structure (?) of the nerves and the mode in which the neurilemma leaves them at the place where they form their anastomoses. a. Portion of the trunk of the cochlear nerve ; b. fasciculi lodged in the osseous zone of the cochlea ; c, c. anastomoses in the middle zone ; d, d, d. the neurilemma leaving the nervous loops, interlacing and forming the basis of the membraneous zone. As to the mode in which the nervous fila- ments enter and terminate in the membraneous labyrinth. The nervous filaments, according to Scarpa, before penetrating the vestibule of the small bony canals, lay aside their thicker sheath, and become softer and whiter. The filaments expand on the parts for which they are destined, appear to form a network, and, having penetrated into the interior, are resolved into a nervous pulp which lines the inner sur- face. Scarpa compares this nervous expansion in the saccule to the retina. According to Breschet's account, the nervous filaments, in penetrating into the interior of the different membraneous pouches, are accompa- nied by a sheath furnished by the pouch itself, which is folded inwards, and accompanies them until these filaments spread themselves out. Hence it is that, at the entrance of the nerves, the walls of the pouch are always thicker, and form a more or less considerable projection in the interior. This prominence is slight in the saccule and common sinus, but very well marked in the interior of the ampullae, where it forms a sort of incomplete septum across ; a structure which is small in man and the mam- mifera, but very much developed in birds and the higher reptiles. At those prominences the nervous filaments, says Breschet, present anastomosing loops, and the neurilemma leaving them to be incorporated with vessels, and thus to form the framework of the membraneous labyrinth, the nervous globules come into immediate contact with the mass of calcareous matter. What I have said of Breschet's account of 542 ORGAN OF HEARING. the terminations of the cochlear nerve is also applicable here. The filaments of the nerves of the common sinus and saccule expand in a fan-like manner on their walls, and having pe- netrated them, are resolved into a nervous layer like the retina, situated on the inner surface of the walls of those cavities. This nervous layer is, in the human ear, pervaded by extremely minute transparent fibres. In the rabbit I have distinctly seen, with a doublet magnifying 150 diameters, a fibrous or tubular structure similar to that of the retina first discovered by Ehren- berg. As regards the entrance of the nerves of the ampullae, Steifensand* gives a similar but more detailed account than Breschet, He says, the nerve, after having embraced in a forked man- ner about a third of the circumference of the ampulla, enters the wall of it. Resolving itself now into infinitely fine fila- ments, the nerve penetrates the septum which lies quite close to the opening in the common sinus, and which resembles a semilunar emi- nence projecting into the interior. It now covers the surface of the septum and a circum- scribed portion of the adjacent inner surface of the wall of the ampulla with an extremely deli- cate nervous pulp. The two ends of the semi- lunar septum, gradually flattening and spread- Fig. 242. Common sinus, together with the ampullee and semi - circular tubes, and the entrance of the nerves into them. ( From Steifensand. ) Fig. 243. The ampullee of the superior and horizontal semi- circular tubes, with a part of the common sinus. The fan-like expansion of the nervous fibrils on the latter is seen, and also the fork-like expansion of the nerves on the outer surface of the ampullee. Magnified, ( From Steifensand. ) * Miiller's Archiv. fur Anatomie, Physiologie, und wissenschaftliche Medecin, 1835. Heft. ii. s. 174 and 184. ing out, lose themselves in the wall of the am pulla. Fig. 244. Fig. 246. Fig. 245. n Fig. 244, (from Steifensand.) The ampulla opened in order to exhibit the septum. Fig. 245, (from Steifensand. ) The fork-like ter- mination of the nerve of the ampulla und the semilunar septum, having the appearance of pure nervous sub- stance. Fig. 246, ( also from Steifensand. J The expan- sion of the nervous pulp over the septum. Bloodvessels of' the labyrinth. — The prin- cipal artery of the labyrinth is the arteria auditiva interior. It is a branch of the basi- lar. It enters the internal auditory meatus along with the nerve of the seventh pair, and at the bottom of it divides into two branches, the cochlear and vestibular arteries, which enter the labyrinth with the corresponding nervous filaments. The cochlear artery, arteria cochlea, divides into a number of branches which enter the cochlea by the spiral tract of holes ; one in par- ticular, arteria centralis modioli, passes through the central canal of the axis as far as the apex of the cochlea. The vessels of the walls of the cochlea are more numerous in the scala vestibuli than in the scala tympani. The arterial branches on the spiral lamina anastomose with each other at the outer margin of the osseous zone. From the convexity of the anastomotic arches nume- rous small arteries arise and run parallel as far as the outer margin of the middle zone, where they again anastomose, forming loops infinitely smaller, from the convexity of which capillary vessels run. These capillary vessels terminate in a sinus of a venous nature, lodged in the substance of the outer margin of the spiral lamina. The vestibular artery, arteria vestibuli, sup- plies the vestibule and semicircular canals to- gether with their contents, the saccule, common sinus, ampulla?, and semicircular tubes, and sends a branch along the surface of the spiral lamina corresponding to the vestibular scala. The stylo-mastoid artery, a branch of the poste- rior auricular, sends a twig to the external semicircular canal. The occipital artery also frequently sends twigs to the labyrinth. The bloodvessels form a beautiful plexus on the ampullae, and considerable trunks run along the whole length of the semicircular tubes, sup- ported on their surface by a delicate cellular tissue, which forms the vehicle for the passage of the small lateral branches given off to the walls of the tubes. ORGAN OF HEARING. 543 Not much is known of the veins of the laby- rinth. The internal auditory artery is accom- panied by a corresponding vein which carries away the blood from the labyrinth, and empties it into the superior petrosal sinus. Another vein, says Weber,* goes perhaps from the laby- rinth through a small opening in the cleft of the aqueduct, and empties itself into the trans- verse sinus. Of the veins of the cochlea, some, according to Breschet, accompany their arteries ; others enter the sinus, lodged in the substance of the outer margin of the spiral lamina. Near the base of the cochlea, this sinus communicates with the veins of the vestibule. Nothing is known of the absorbents of the labyrinth. Fig. 247. A section of the cochlea parallel to its axis, showing the distribution of the vessels in its interior. It is the veins that are delineated, but their distribution is almost the same as that of the arteries. Magnified. ( From Breschet.) a, a. Veins accompanying the trunk of the coch- lear nerve, and penetrating the nervous branches across the spiral lamina ; b. first anastomoses at the periphery of the osseous zone ; c, c. second anasto- moses at the periphery of the middle zone ; d. last ramuscules, which are almost parallel, occupying the membraneous zone ; e, e, e. venous sinus in the peripheral margin of the membraneous zone. II. Accessory parts of the apparatus OF HEARING. Of these parts, the auricle collects the so- norous undulations, and the auditory passage conducts them to the middle ear or tympanum, where they are modified and transmitted to the sensitive part of the apparatus, the ear-bulb. A tympanum is found in reptiles, birds, and Mammifera, a perfect external ear only in the Mammifera. The lip-like folds of skin before the membrana tympani, in some birds and rep- tiles, may, however, be considered rudiments of an external ear. Among the Mammifera, the Cetacea have no auricle, and only a very contracted auditory passage. It was said that the tympanum exists in a greater number of animals than the cochlea. This refers to a discovery made by Weber,f that a prolongation of the swimming-blad- * In Hildebrandt's Anatomie. t De Aure et auditu Hominis et animalium, Lipsiae, 1820. der in the herring, in the cyprinoid fishes, in silurus glanis, and in several species of cobitis, has a connexion with the membraneous labyrinth in the same manner that the prolon- gation of the mucous membrane of the throat, forming essentially the tympanum and Eusta- chian tube, is extended to the surface of the labyrinth ; and moreover, that in all those fishes, with the exception of the herring, there exist bones analogous to the tympanic ossicles in the higher animals. 1. The middle ear, or tympanum, and its ap- pendages. The cavity of the typunum, cavitus tympani; Fr. cuisse du tympan ou du tambour ; Germ, die Trommelhohle oder Paukenhohle. — The cavity of the tympanum is a space lying at the peri- pheral surface of the ear-bulb, and measuring from above downwards as well as from before backwards about four-tenths of an inch, and from without inwards about three-twentieths of an inch. It is bounded internally by the outer wall of the osseous labyrinth ; externally by a vibratile membrane, the membrana tympani, and that portion of the temporal bone into , which it is framed. Anteriorly a canal, the [' Eustachian tube, leads from it into the throat ; and posteriorly and superiorly it communicates with the mastoid cells. The cavity of the tympanum is traversed by a chain of small bones, extending from the membrana tympani to the vestibular fenestra, and is lined by a very delicate membrane of a fibro-mucous character, which is prolonged into all its sinuosities and dependent cavities. This membrane is moreover reflected on the parts which traverse the cavity, and envelopes them. The lining membrane of the tympanum is con- tinuous through the medium of that of the Eustachian tube, with the mucous membrane of the throat. A condition essential to the due performance of the function of the tympanum is that the external air have free access to its cavity. Examined on the dry bone, the inner wall of the tympanum presents a considerable emi- nence; behind and below which is an opening somewhat of a triangular form, and in a fossa above it another opening, about twice the size of the preceding, and of an ovoid shape. From the description which has been already given of the osseous labyrinth,' it will be immediately perceived that the eminence in question, called the promontory, is that which the commence- ment of the cochlea forms; that the opening below and behind it is the fenestra rotunda or cochlear fenestra, and the opening above it the fenestra ovalis or vestibular fenestra. The surface of the promontory is marked by a groove ; sometimes instead of a groove there is a canal. This groove is continuous below with a canal, several lines in length, which opens in that depression in the partition be- twixt the lower orifice of the carotid canal and the foramen lacerum posterius. Above, in front of the vestibular fenestra, the groove again runs into a canal which proceeds forwards and up- wards between the canal for the internal muscle of the malleus and the commencement of the 544 ORGAN OF HEARING. aqueduct of Fallopius, and opens on the upper surface of the petrous portion of the temporal bone outside and in front of the hiatus of Fal- lopius. This canal, first accurately described by Arnold,* and called by him the tympanic canal, cana/is tympanicus, is traversed by the nerve of Jacobson, which establishes a com- munication betwixt the glosso-pharyngeal and the otic ganglion. Besides this groove there are several others corresponding to the branches of the tympanic plexus of nerves. The opening below and behind the promon- tory, the fenestra rotunda or cochlear fenestra, leads, by a short infundibuliform canal directed obliquely inwards, into the lower or tympanic scala of the cochlea. Looking into this very short canal sideways, a groove is remarked en- circling the margin of its inner orifice. This groove receives the circumference of the secon- dary membrane of the tympanum. The opening above the promontory, the fe- nestra ovalis or vestibular fenestra, has already been described in speaking of the vestibule. All that we have to add here is that it is sur- rounded externally close to its edge by a small channel or groove. Above the vestibular fenestra and running in much the same direction as its long diameter is a round elongated ridge, within which is the aqueduct of Fallopius. Below this ridge and behind the vestibular fenestra is a small mam- millary or pyramidal eminence, called the pyra- mid, eminentia papillaris s. protuberantia py- ramidalis. The apex of the pyramid, directed forwards and a little outwards, presents an opening leading into a canal, which extends backwards and downwards, then becom.ng vertical lies in front of the lower part of the aqueduct of Fallopius. In the thin lamina of bone which separates the two canals there is an aperture. The muscle of the stapes is lodged in the canal, and its tendon issues by the aperture in the apex, of the pyramid. About one-sixth of an inch behind the pyra- mid and close to the groove for the insertion of the circumference of the membrana tympani is the opening by which the chorda tympani, accompanied by an artery, enters the tym- panum. In front and a little above the vestibular fenestra, and on the anterior extremity of the prominence of the aqueduct of Fallopius, is a tubular projection with a wide open mouth directed outwards. This tubular projection, •which is generally found incomplete in the dry bone, in consequence of being composed of a very thin brittle substance, is what has been called the cochlear ij'orm process. It is the continuation, bent at nearly a right angle outwards, of the canal or half canal, about half an inch in length, and destined for the recep- tion of the internal muscle of the malleus, which lies above the osseous part of the Eusta- chian tube, and is separated from it merely by * Ueber den Canalis tympanicus und mastoideus, in Tiedemann's, Treviranus, und Gmelin's Zeit- schrift fur die Physiologie, B. iv. Heft 2, No. xxi. p. 284. a thin lamina of bone, the continuation of that forming the tubular projection. Fig. 248. The inner wall of tfie tympanum. a. Promontory; b. vestibular fenestra; c. coch- lear fenestra ; d. pyramid ; e. eminence of the aqueduct of Fallopius ; f. cochleariform process and half canal for the internal muscle of the mal- leus. The outer wall of the tympanum is formed by the membrana tympani and the inner ex- tremity of the osseous part of the external au- ditory passage, in which the membrana tympani is framed. Osseous portion of the auditory passage. — This leads from the outside of the temporal bone. In front of it lies the glenoid cavity, and behind it is the mastoid process. It is about three-quarters of an inch long. Its course is from without inwards and from behind forwards, at first a little upwards and then downwards. It is wider at either extre- mity than in its middle. A cross section of the passage presents an elliptical orifice, the long diameter of which is directed from behind forwards and from below upwards. Its extre- mities are cut obliquely in such a way that in- ternally the anterior wall exceeds the posterior, whereas at the outer orifice the posterior wall exceeds the anterior in length. The margin of the outer orifice is rough and irregular to give attachment to the cartilaginous portion of the passage and to the auricle. Just within the inner orifice the osseous auditory passage is grooved all round except at its upper part. This groove is for the reception of the circumference of the membrana tympani. In the foetus the osseous portion of the audi- tory passage is a mere ring of bone, the tym- panic ring, incomplete at the upper part where the groove in the adult is wanting. The tym- panic ring serves as a frame for the membrana tympani. On the inner surface of the superior extremity of the anterior cms of this incomplete ring of bone there is a broad superficial groove, into which the processus gracilis of the malleus is received. By-and-bye the tympanic ring is united to the temporal bone, and in process of time the part outside the groove grows outwards so as to form that plate of bone, thick behind, thin in front, rolled together in the form of an incom- plete tube, which in the adult composes the lower, the anterior, and the posterior walls of the osseous auditory passage. ORGAN OF HEARING. 545 The tympanic ring lies immediately behind the glenoid cavity of the temporal bone, from which its anterior part is separated by a fissure. The middle part of this fissure, together with a line indicating the whole, remains permanent in the adult, and is known by the name of fissure of Glasser. Its internal orifice is, in the adult as it is in the young bone, in the outer wall of the tympanum, anteriorly of, and close to the groove for the reception of the membrana tympani. The fissure of Glasser gives passage to the ligament, or so-called great external muscle of the malleus, which is inserted into the processus gracilis of the malleus. The chorda tympani does not actually pass through the fissure of Glasser as commonly described, but as M. Huguier* has shown, through a par- ticular canal, extremely narrow and about half an inch long, which runs in the line of the fissure, and opens at the re-entering angle be- tween the squamous and petrous portions of the temporal bone. • Membrane of' the tympanum, ( membrana tym- pani, Fr. la membrane, du tympan ou du tam- bour,) Germ, das TrommetfeU oder Pauken- j'ell. — A proper membrana tympani exists only in birds and mammifera. In reptiles there is a very imperfect representation of one. In birds the membrana tympani is convex externally, in the mammifera, on the contrary, it is concave. The convexity externally in birds forms a very important distinguishing character of the class. In the cetaceous mammifera the membrana tym- pani is thick, and presents a prolongation like the tube of a funnel into the cavity of the tym- panum. The membrana tympani is situated at the bottom of the external auditory passage, be- tween which and the cavity of the tympanum it is interposed like a partition. It is a thin, semi-transparent, glistening, dry-looking mem- brane. Its shape is an oval, truncated at one extremity, the upper. Rather more than the upper half of its vertical diameter is traversed by the handle of the malleus, which, when the membrane is examined on the living subject by means of the speculum auris, appears directed from above downwards and backwards. The longest diameter of the membrana tym- pani, which is directed from above downwards, and from behind forwards, is about eight- twentieths of an inch, and its shortest, that from behind forwards, somewhat less than seven twentieths of an inch. It is fixed by its cir- cumference in the circular groove already men- tioned, at the inner orifice of the osseous part of the external auditory passage, or in the foetus, the tympanic ring; and as in the adult the ori- fice is cut obliquely from behind forwards, from above downwards, and from without in- wards, so is the direction of the membrane. Hence it forms, with the upper and posterior wall of the auditory passage, an obtuse angle, and with the lower and anterior wall, an acute angle. Figure 249 represents the adult membrana * Cruveilhicr, Anatomie Descriptive, tome iii. p. 508. VOL. II. tympani of the right side; a. as seen from the auditory passage ; b. as seen from the tympa- num. Its shape, size, the mode in which the malleus is connected with it, and the cartila- ginous ring which forms its circumfeience, are sufficiently well shown. Fig. 249. The membrana tympani does not present plane surfaces. On the contrary its centre is drawn inwards, so that it is concave externally, and convex internally. This disposition of the membrana tympani depends on its connexion with the handle of the malleus. The latter being- fixed in its whole length to considerably more than the upper half of the vertical diameter of the former, and having an inward direction in- fenorly, the membrana tympani is, as it were, drawn inwards to it, hence the concavity ex- ternally. As regards the composition of the membrana tympani, it consists of a proper membrane and two borrowed layers, one of . which, covering the external surface of the proper membrane, is a delicate continuation, in the form of a blind end, of the lining of the auditory passage, and the other, situated on the inner surface, is a continuation of the delicate membrane which gives a lining generally to the cavity of the tympanum. The latter adheres very closely to the proper membrane, the other not so inti- mately, as it readily separates from it by putre- faction, and can be drawn out along with the rest of the epidermis of the external auditory passage in a cul-de-sac. Structure of the proper membrane.- — The pro- per membrane can be divided into two layers, an outer thin one, consisting of radiating fibres, and an inner thicker layer, which is less dis- tinctly fibrous, though, when torn it does indi- cate a fibrous disposition, and that in a direc- tion opposite to the former. The radiating fibres run from its circumference towards the centre, to be fixed to the handle of the malleus along its whole extent. Towards the centre they become stronger, and being, of course, more asrgregated, the layer which they compose is thicker and more compact in the centre than towards its circumference. The fibres which cross the radiating ones are also more aggre- gated at the centre. They run parallel with the handle of the malleus, and turn round its extremity. At the circumference of the proper membrane, there is a thick firm ligamen- tous or cartilaginous ring, (Jig. 249,) which is fixed in the groove of the bone. This liga- mentous ring appears to be formed by an ag- gregation of the circular fibres interwoven with the peripheral extremities of the radiating ones. The part of the membrana tympani midway between its centre and circumference is the thinnest. The radiating fibres have been supposed to 2 o 546 ORGAN OF HEARING. be muscular by Sir Everard Home and others, but this has not been confirmed by microscopi- cal examination. Mr. Shrapnell* describes at the anterior and superior part of the membrana tympani, above the short process of the malleus and its suspen- sory ligament, and where the groove in the bone is deficient, a flaccid tissue, composed of irre- gularly arranged fibres, to which he gives the name of membrana Jiuccida, in opposition to the re>t of the membrana tympani, which he calls membrana team. This flaccid tissue is more developed in some of the lower animals, the sheep and hare for instance, than in man, and can be readily made to bulge out towards the auditory passage by blowing air into the Eusta- chian tube. But we cannot look upon it, with Mr. Shrapnell, as properly forming any part of the membrana tympani. It is merely a mass of dense, reddish, vascular cellular tissue, sur- rounding the neck of the malleus, and conti- nuous with a similar tissue found under the lining integument of the upper wall of the osseous auditory passage. It is this same tis- sue which has been described as a muscle, and sometimes as a ligament. The membrana tympani has been said to present in the natural state a perforation closed by a valve. Rivinus,-f though not the first to mention it, dwelt on it, however, in a parti- cular manner, hence the perforation has been called hiatus Rivinianus. The subject has been more recently taken up by Wittmann and Vest.} The membrana tympani receives a nerve from the third division of the fifth, which has communications with filaments of the chorda tympani. To resume our description of the cavity of the tympanum: — In the upper wall of the tympanum there is an excavation for receiving the upper part of the incus, and leading from that, at the upper and back part of the tympa- num, is a short, wide, triangular canal, with a rough cellular surface. This is the passage to the mastoid cells, through the medium of a large cell, sinuosiias mastoidea s. sinus mammil- laris, s. antrum mammillare, which already ex- ists in the young bone between the squamous and petrous portions. The mastoid cells are cavities in the mas- toid process, all communicating with each other. They are quite irregular in regard to size, number, and relative situation. In early life, as the mastoid process is not fully formed, they do not exist, they are only found com- pletely developed in the adult. Inferiorly, the cavity of the tympanum forms a sort of furrow, which presents nothing parti- cular. It is bounded by the plate of bone which forms the outer wall of the jugular fossa. * On the form and strueture of the membrana tympani, in London Medical Gazette, vol. x. p. 120. London, 1832. t De audhus vitiis, Lipsiae, 1717, 4, p 32. Tab. adj. Fig. 1, b. et fig. 2, b. X Ueber die Wittmannsche Trommelfellklappe, in den medizinisch. .lahrbiichern des oestr. Staates. Bd. v. Wien, 1819, p. 123, 133. Anteriorly, the cavity of the tympanum opens into the osseous portion of the Eustachian tube. The ossicles or small bones of the ear (ossi- cula auditus s. aurium, Fr. osselets de I' ouie ; Germ. dieG eh'6rkn'6chelchen,orG eh'urbeinchen ). In the upper part of the cavity of the tympa- num, there are three small bones articulated with each other, and forming a chain which reaches from the membrana tympani to the ves- tibular fenestra. The bones are named malleus, incus, and stapes, from their resembling more or less respectively a hammer, an anvil, and a stirrup iron. The innermost and most essential is the sta- pes ; it is it alone which in birds and reptiles remains, when the others have disappeared, or been reduced to merely cartilaginous pieces. The stapes is engaged in the vestibular fenes- tra. The outermost of the chain, the malleus, is in connexion with the membrana tympani. The hammer bone, (malleus,) Fr. le marteau, Germ, das Hammer, presents a head, a neck, a handle, and two processes, one longer, and one shorter. The head, caput s. capitulum, is round and smooth on one surface, and on the other pre- sents a saddle-shaped depression, surrounded by a small elevated border. The depression articulates with the incus, and the border is for the attachment of the synovial capsule of this minute joint. The neck, collum s. cervix, is flattened in one diameter, and joins the handle at an obtuse angle. The handle, manubrium mallei, compressed from the side corresponding to the articular depression to the opposite side, and diminish- ing in thickness towards its extremity, forms, together with the short process, a double curve, like an Italic f. The extremity is also com- pressed, as if beaten flat, but in an opposite di- rection, so that the broad surfaces of the extre- mity correspond to the edges of the rest of the handle. Short or blunt process, processus brevis s. obtusus. From the projecting side of the an- gle formed by the junction of the neck and manubrium, this process, which is short, thick and conical, rises. The long or slender process, processus longus, s. gracilis, s. spinosus, s. Folii, springs from the neck, and from that side of it which corres- ponds with the non-articular surface of the head. The long process is of considera- ble length, and terminates in a broad, flat, spatula-like extremity, first described by Rau,* although the commencement or root of the process itself had been previously delineated and described by Folius. The long process is generally found broken off, either from its being so slender, or from its having been, especially in old subjects, united to the groove in which it is lodged. The anvil bone, incus, Fr. Venclume, Germ. * Boerhaave Praelect. in Tnstitt., Prop. iv. p. 358. ORGAN OF HEARING. 547 der Amboss. — This has been compared, also, to a bicuspid molar tooth. It is divided into a body, and two processes, or crura. The body, corpus, presents a concave articu- lar surface, by which it is joined to the malleus : around this surface is a groove, (particularly deep and broad on the side towards the laby- rinth, that is, the side on which the lenticular process projects,) for the insertion of the articu- lar capsule. The shorter of the two processes, crus s. pro- cessus superior s. brevis, is blunt at its apex, and compressed from one side to another. The longer process, crus s. processus inferior s. longus, is more slender, and becomes gradually thinner towards its extremity, where it is slightly curved, and where it presents, supported on a short bony pedicle, given off at a right angle from its side, the lenticular process, processus lenticularis incudis ;*' — a small oval plate so situated, that a line drawn through the long diameter of it would intersect obliquely a line corresponding to the long crus of the incus. The free surface of the lenticular process is convex, and is destined to articulate with the corresponding concave surface on the head of the stapes. The lenticular process has been, and is still, often described as a separate bone, under the name of os lenticulare. The stirrup bone, ( stapes ). Fr. Uetrier. Germ. Der Ziteigbiigel. — Exactly like a stirrup, this bone presents a base, two crura, and a head, where the crura unite. The base, basis, the essential part of the bone, has precisely the same shape as the vestibular fenestra to which it is applied, only a little smaller. The arched margin of the base cor- responds to the upper edge of the fenestra, and the indented margin to the lower edge. The surface of the base corresponding to the vestibular fenestra is slightly convex. The other surface is grooved ; but the groove is subdivided by a ridge, which extends obliquely along it lengthways, and which is continuous at its ex- tremities with the upper margin of the groove on the inner surface of one crus, and the lower margin of the groove of the opposite crus. The margin of the base projects like a ledge beyond the insertion of the crura. Of the two crura, one is shorter and straighter than the other ; both are grooved on the surfaces regarding each other, and the grooves are con- tinued into that just described in the base, in such a way that the groove of one crus is con- tinued into one of the divisions, and the groove of the other crus into the other. The head, capitulum, somewhat oblong and flat, presents a superficial depression on its top, oblique from above downwards, and from with- out inwards, for receiving the convex articular surface of the lenticular process of the incus. There is sometimes an appearance of a neck supporting the head. Position, connexions, and articulations of the small bones of the tympanum.- — The handle of * Blumenbach, Geschichte, und Beschreibung der menschl. Knochen, s. 50, p. 145. Fig. 250. Small bones of the tympanum of the left side, mag- nified considerably more than twice. ( f rom Soem- mering.) A is the malleus seen from the side correspond- ing to the membrana tympani : a. head ; b. articu- lar surface ; c. neck; d. handle; e. short process ; f. long process. B. The incus seen from its outer surface also : a. body ; b. articular surface ; c. short crus ; d. long crus ; e e. lenticular process. C. The stapes: a. head; b. neck; c. anterior and less bent crus ; d. posterior and more bent crus ; e. base. D. A fore-shortened view of the stapes : a. an- terior and less curved crus ; b. posterior crus, the two are seen uniting at the head, the articular sur- face of which is seen; c. base. the malleus is fixed to the membrana tympani. The articular surface on the head of the malleus, to the corresponding surface on the body of the incus, and the long process of the incus, is through the medium of its lenticular process articulated with the stapes. These two joints are furnished with small articular capsules. The head of the malleus lies in the upper space of the tympanum, above the upper margin of the membrana tympani. Its articular sur- face is directed obliquely backwards and in- wards. The surface of the neck, corresponding to the prominence of the angle which it forms with the manubrium, is hitched like a shoulder under the upper part of the circumference of the inner extremity of the auditory passage. The handle of the malleus, it has been said, is compressed from one side to another, so that it presents two flat surfaces and two edges or ridges. That edge or ridge which is continued down from the short process is turned outwards, and corresponds to the membrana tympani ; into it, indeed, along its whole extent, the cen- tral extremities of the radiating fibres of that membrane are inserted. The extremity of the handle of the malleus, which is curved forwards and outwards, is compressed, but in a direction contrary to the rest of the handle ; so that one of the flat surfaces, that corresponding to the outer ridge of the rest of the handle, is con- nected with the membrana tympani at a point below its centre, and nearer its anterior edge. It is at this point that the bottom of the con- cavity is which the membrana tympani presents externally. At its upper part the membrana tympani is pushed outwards by the short pro- cess of the malleus, which projects towards the auditory passage. 2 o 2 548 ORGAN OF HEARING. The long process of the malleus is directed forwards, and lies in a groove within the anterior part of that for the reception of the membrana tympani, and close to the fissure of Glasser. To the top of the head of the malleus, a ligament extends downwards from the upper wall of the cavity of the tympanum. Another ligament, known also under the name of the great external muscle of the malleus, proceeds from the spinous process of the sphenoid bone backwards and inwards, through the fissure of Glasser, and is inserted into the long process of the malleus. A third ligament has been de- scribed, as arising from within the upper and posterior margin of the inner orifice of the auditory passage above the margin of the niem- brana tympani, and proceeding downwards and inwards to be inserted into the handle of the malleus below the short process, close to the place where the connexion between the handle of the malleus and the membrana tympani ceases. Of this ligament, which has also been described as a muscle, small external muscle of the malleus, there is not much trace, except in the reddish cellular tissue already mentioned. The body of the incus lies in the upper and posterior part of the tympanic cavity. Its articular surface, corresponding to that of the malleus, is directed forwards, and a little up- wards and outwards. The articulating surfaces of the two bones are incrusted with cartilage, and the joint is provided with a synovial mem- brane, which is strengthened by ligamentous fibres. The short branch is directed horizon- tally backwards towards the entrance into the mastoid cells, and is there fixed by means of a short and broad ligament, which arises from a small pit in the outer wall, and embracing its extremity, is inserted on it. The long branch extends perpendicularly downwards, almost pa- rallel with the handle of the malleus, but nearer the inner wall of the tympanum, towards which its extremity, bearing the lenticular process, is curved. The stapes, situated lower down in the cavity of the tympanum than the other bones, lies with its base applied to the vestibular fenestra, to the circumference of which it is closely fixed by a circular ligament, ligamenhm annulare buseos stapidis. This ligament springs from the margin of the vestibular fenestra, and is inserted into the jutting margin of the base of the stapes all round. Besides this ligament, there are re- flections of the membrane lining the tympanum, and of that lining the vestibule. The con- nexions of the base of the stapes with the ves- tibular fenestra are such as to admit of some degree of movement, but not to any very great extent, — so little, that it would seem one object of the mechanism of the fenestra ovalis, and its closure by the base of the stapes, was merely to interrupt the continuity of the osseous walls of the vestibule. The short branch of the stapes is in front ; the long branch behind, and its head outwards, where it meets and art.culates with the lenticu- lar process of the Ion? branch of the incus. This articulation presents also cartilages of in- crustation, and a minute synovial capsule, to- gether with strengthening ligamentous fibres. Fig. 251. The small bones connected together, and their relation to the osseous labyrinth. Left side. Magnified. ( From Soemmerring . ) Muscles of the small bones. — Some anatomists admit four muscles : three attached to the mal- leus and one to the stapes. Of the three at- tached to the malleus,two are described as having for their action the relaxation of the membrana tympani; but these so called laxutores tym- pani are merely ligaments, and have been de- scribed above as such. I agree with Hagen- bach,* Breschet,t and Lincke,J that two muscles only can be distinctly demonstrated, and these two are both tensors of the tympanum. A relaxation, or state of rest of the membrana tympani, takes place of itself, as Treviranus§ remarks, when the tensors cease to act; hence a relaxator muscle of the membrana tympani was not required Muscle of the malleus, musculus interims mallei s. tensor tympani. — This muscle occupies the canal, or half canal, which was described as lying above the osseous part of the Eustachian tube. It arises from the posterior and under part of the sphenoid bone, from the superior part of the cartilaginous portion of the Eusta- chian tube, and also from an aponeurotic sheath which lines the canal, or completes the groove in which it is lodged. Its fibres proceed from before backwards, and terminate in a slender tendon, which bending at a right angle, as a rope over a pulley, enters the cavity of the tympanum, through the tubular projection al- ready described as a continuation of the canal in which it lies. Having entered the tympanum, it proceeds outwards, and is inserted into a slight elevation, sometimes remarked on the inner and anterior surface of the handle of the malleus below the long process, and also a little below and opposite the root of the shoit * Disquisitiones anatomicae circa miisculos amis intern* hominis et Mammalium, &c. Basileae, 1833, p. 20. t Op. cit. s. xxxiii. } Das Ciehororgan, &c. Leipzig, 1837, p. 140, s. 114. § Biolo^ie, Band. vi. p. 376. ORGAN OF HEARING. 546 process. The muscle of the malleus receives a nervous brand) from the otic ganglion. By the action of this muscle, the handle of the malleus is drawn inwards and forwards, whilst the head is moved in the opposite direc- tion, in consequence of the bone moving on its long process as on an axis. The result of this movement of the bone is, that the membrana tympani, which is attached to the handle of the malleus in its whole length, is also drawn in- wards and stretched. Besides the tension to which the membrana tympani is thus subjected, the base of the stapes is forced against the ves- tibular fenestra, m consequence of the move- ment communicated by the head of the malleus to the incus, which tends to press inwards the long extremity of the latter. Muscle of the stupes, M. stapedius. — This is lodged, and takes origin in the cavity of the pyramid already described. Much paler and smaller than the preceding muscle, it is inserted into the posterior and upper part of the head of the stapes by a slender tendon, which issues by the aperture in the summit of the py- ramid, and proceeds downwards and forwards to its termination. The stapedius muscle receives a nervous fila- ment from the facial nerve. The first effect of the action of this muscle will be to press the posterior part of the base of the stapes against the vestibular fenestra. At the same time the long branch of the incus will be drawn backwards and inwards, and the head of the malleus being, by this movement of the incus, pressed forwards and outwards, its han- dle will be carried inwards, and the membrana tympani thus put on the stretch. Breschet calls the muscle of the stapes a iaxator, but I do not know on what grounds. Magendie* mentions the circumstance that in the stapedius muscle of the ox and horse, there is imbedded a small lenticular bone. Professor Berthold of Gbttingenf has more lately called attention to the same circumstance. Berthold has not found this bone in man, nor sheep, nor deer, nor goats, nor swine. In the ox and calf it is about one-half to three-fourths of a line in its longest diameter, and one-third in the shortest, and lies surrounded by the mus- cular and tendinous substance where the for- mer passes into the latter. In the horse it is a little nearer the lower margin of the muscle and tendon, and is much smaller than in the ox; moreover, it is not round, but is a longish plate, somewhat thicker in the middle. At the place where the stapedius muscle is inserted into the stapes, HyrtlJ has sometimes found in the human ear a small process of bone which in some cases was so long as to extend * Sur les organes qui tendent ou relachent la mem- brane du tympan et la chaine des osselets de l'ouie dans l'homme et les animaux mammiferes. In Journal de Physiologie experimental, t. 1., p. 346. Paris, 1821. t Ueber ein linsenformiges Kndchelchen im Musculus Stapedius mehrerer Saugethiere. In Mueller's Archiv. Jahrg. 1838. i Beitr'age zur patbologischen Anatomie des Gehbrorgans, in the Medicin. Jahrb'ucher . des k. k. oestr. Staates. Wien 1836. Bd. xx. p. 439. into the belly of the muscle itself. Teichmeyer* has described this free bone of the stapedius muscle as constant in man. Having described the walls and contents of the cavity of the tympanum, we come now to speak of the membrane which lines it. The lining membrane of the cavity of the tympanum is in continuity with the mucous membrane of the throat, through the Kustachian tube. Extremely delicate, and in some parts very vascular, it is not merely a mucous membrane, but is theoretically a combination of periosteum and mucous membrane, being what Bicbat called fibro-mucous. It invests all the elevations and depressions observed on the walls of the tympanum, and extends into the mastoid cells. The outer layer of the mem- brane of the fenestra rotunda, membrana tym- pani secundaria, is a continuation of it. The base of the stapes is fixed by its circum- ference to the outer edge of the groove, which encircles the vestibular fenestra, by a membrane or ligament. The lining membrane of the ves- tibule, continued over the base of the stapes from within, also invests the inner surface of this annular ligament, whilst the outer surface of it is covered by the membrane lining the tympanum as it is reflected on the stapes. The membrane lining the tympanum invests the small bones and the tendons of their mus- cles where they run free in the cavity. A fold of it fills up the space bounded by the crura and base of the stapes. The chorda tympani, also, in its passage across the tympanum, is enve- loped by it. Lastly, it forms the inner bor- rowed layer of the membrana tympani, cover- ing and adhering closely to the handle of the malleus. The Eustachian tube, ( tuba Eustachii, s. ca- nalis pulatinus tympani; Fr. la trompe d'Eus- tuclii ; Germ, die Eustuchische Rohre oder der Gaumengang des mittlcren Ohrs.) — The Eustachian tube is a passage of communication betwixt the cavity of the tympanum and the throat. In length about an inch and a half, it is directed from behind forwards, from without inwards, and from above downwards. Its gut- tural orifice is wider than that by which it opens into the tympanum. Proceeding from the tympanum, its first part is an osseous canal, the osseous part of the Eus- tachian tube; the walls of the remainder of it are composed partly of cartilage, partly of fibrous membrane, the cartilaginous and mem- braneous portion of the Eustachian tube. The osseous part of the Eustachian tube, pars ossea tuba Eustachii, begins at the anterior and lower part of the tympanum, by a funnel-like orifice, and runs forwards and inwards on the outside of the carotid canal, and below that for the reception of the internal muscle of the mal- leus. It is about half an inch in length, and ends by a notched and irregular edge at the re- entering angle, between the squamous and petrous portions of the temporal bone. Its calibre contracts in its course forwards, and is compressed from without and below inwards * Vindiciae quorundam inventorum anat. in dubium vocatorum. Heme. 1727. 4. 550 ORGAN OF HEARING. and upwards. In the dry bone it is wide enough to admit the end of a quill stripped of its feathery part, about one-twelfth of an inch thick. In the recent state, when lined by its mucous membrane, it is very much narrower. The car tilaginous and membraneous portion of the Eustachian tube, pars curlitagineaet mem- branacea tuba Eustac/ut. — In the skull it is ob- served that the osseous part of the Eustachian tube is continuous with a sort of gutter which is formed by the outer and anterior side of the petrous bone, and the posterior inner and lower margin of the great wing of the sphenoid bone. To this gutter the external wall of that part of the Eustachian tube under consideration, which is partly cartilaginous and partly fibro-membra- neous, corresponds at its tympanic extremity; towards the guttural orifice of the tube, the membraneous wall is applied against the circum- flex muscle of the palate. The inner, and also the upper wall of this portion of the Eustachian tube, is formed of a grooved cartilaginous la- mina of a triangular form, fixed by dense cel- lular tissue to the irregular extremity of the osseous portion, to the apex of the petrous bone, and to the root of the inner plate of the pterygoid process of the sphenoid. At the guttural orifice of the Eustachian tube, it forms a semilunar prominence with its convexity turned upwards and backwards. The cartila- ginous plate of the outer wall does not extend to the mouth of the tube, but only fills up that place where the outer wall of the bony groove above-mentioned as continuous with the osseous part of the Eustachian tube is defective, that is, from before the foramen spinosum of the sphe- noid to the scaphoid fossa at the root of the in- ner plate of the pterygoid process. The cartilaginous and membraneous portion of the Eustachian tube is about one inch long. Being compressed from within outwards, a sec- tion of it is an elliptical fissure. From its junc- tion with the osseous portion, it goes on widen- ing, so that the point of junction is the narrow- est part of the tube; — in the recent state, about one-thirtieth of an inch in diameter, just suffi- cient to admit a small probe. The mouth of the Eustachian tube in the throat forms an oval-shaped fissure, about three-eighths of an inch long, bounded ante- riorly and posteriorly by prominent swollen edges. The fissure is directed obliquely from above downwards, and from before backwards, and is situated at the upper and lateral part of the pharynx behind the soft palate. In refe- rence to the nasal passage, my observation agrees with that of Kramer,* that the lower angle of the guttural orifice of the Eustachian tube lies a very little deeper than the horizontal line of the lowest meatus, whilst the upper angle is a little deeper than the horizontal line of the middle meatus. The Eustachian tube is essentially a tegumen- tary canal ; through it atmospherical air is ad- mitted into the tympanum, a condition which, by keeping up an equable pressure on either side of the membrana tympani, and giving free * Die Erkenntniss unci Heilung der Ohrenkrank- heiten. Berlin, 1836. p. 243. scope to the play of the small bones upon each other, is necessary for the perfect exercise of hearing. Its lining membrane is continuous with that of the throat on the one hand, and with that of the tympanum on the other. At the guttural orifice of the tube, it has all the properties of the mucous membrane of the nose and throat ; as it approaches the tympa- num it becomes thinner and finer, until it assumes all the characters of the fibro-mucous lining of the tympanum. Within the osseous portion of the tube, it no longer presents any of the mucous glands which are found in the mucous membrane of the prominent edges of the guttural orifice, and in that lining the carti- laginous and membraneous portion — mucous glands, which perform so important a part in the economy, and particularly the morbid states, of the Eustachian tube and apparatus of hear- ing generally. Fig. 252. The two muscles of the small bones, and the Eusta- chian tube. ( From Soemmerring.) a. b. c. d. Eustachian tube ; e. muscle of the mal- leus ; f. the muscle of the stapes. 2. The external ear, including the auditory passage. A. The auricle or the ear, ( auricula s. pin- na,) Fr. pavilion de L'oreille; Germ, das Ohr. — The human auricle, as is known, presents on the surface directed outwards, prominences bounding gutter-like depressions, which wind like a maze in different directions; but all lead at last into the auditory passage. Considered in a general way, the surface directed outwards is concave. The surface turned towards the side of the head is, on the contrary, generally speaking, convex, but it is depressed at the places corresponding to the elevations on the outer surface, and more elevated where the de- pressions are. The hem-like fold of the edge of the ear all round is called helix. The eminence within the helix is called ant helix, and the gutter-like depression between the two is called the navi- cular fossa. At its upper extremity the anthe- lix divides into two branches, between which is a triangular depression called fossa innominata. The lower extremity of the anthelix runs into a projection called antitragus, opposite which, and under the anterior part of the helix, is a broad projecting plate called tragus, which lies over the entrance of the auditory passage ORGAN OF HEARING. 551 like a valve. The posterior margin of the tragus, and anterior margin of the antitragus, meet inferiorly; but superiorly they are sepa- rated by a considerable notch. Bounded by the anthelix, tragus, and antitragus, and tra- versed horizontally by the commencement of the helix, is a deep cavity, called concha, at the an- terior part of which is the auditory passage leading from it, as the pipe from the mouth of a funnel. The lower pendulous part of the ear is called lobule. The cartilage of the ear is covered by peri- chondrium, which imparts considerable strength to it. When the perichondrium is removed by dissection, the cartilage is found to be very brittle. Fig. 253. a. b. c. d. e. the helix ; f.g. the upper and lower crura of the anthelix ; h. the point of junction of the two crura ; i. h. the anthelix ; I. tragus ■, m. antitragus ; n. lobule ; o. navicular fossa p. fossa innominata ; q cavity of the concha ; r. entrance of the auditory passage. The auricle of the left side ( reduced in size ). ( From Soemmerring . ) Stripped of the skin which invests it, the auricle is found to be composed of a cartila- ginous skeleton, on which its elasticity depends. The skeleton presents, with some modifications, all the eminences and depressions we have de- scribed, except the lobule, which consists merely of a prolonged fold of skin, between the layers of which is cellular and adipose tissue. In the skeleton of the auricle, the helix com- mences by an acute point in the excavation of the concha. Gradually becoming broader and more elevated, it proceeds obliquely up- wards and forwards, then turning round the upper margin of the ear, contracts in breadth ; and about the middle of the posterior margin, its hemlike fold having ceased, its simple edge is continued into a free tail-like process of car- tilage, which is separated by a fissure from the antitragus. On the anterior part of the helix above the tragus, there is a mammillary process of cartilage which gives attachment to a liga- ment. Behind and below the root of this mammillary process, there is a small vertical fissure in the helix, incisura helicis. Regarding the anthelix there is little more to be said, except that the lower branch of its upper extremity forms a very prominent crest ; and that inferiorly the anthelix is continued into the same tail-like process that the helix runs into, and is also partly continued into the anti- tragus. The antitragus is a small plate of cartilage, forming an angle, directed upwards and forwards. It is continuous by its base with the cartilage of the concha. The lobule hangs from the antitragus, and the tail-like process of cartilage common to the helix and anthelix. Tragus. — Between the helix and tragus there is no connexion by cartilage. The space is merely filled by a continuation of the fibrous cellular tissue which constitutes the upper and posterior part of the cartilaginous and mem- braneous portion of the auditory passage. Fig. 254. a. a. a. a. helix ; b. ant- helix ; c. two crura of anthelix ; d. cavity of the concha ; e. antitragus ; f. tragus ; g. fissure be- tween the tragus and commencement of carti- laginous portion of the . auditory passage, the larger fissure of Satito- rini. Skeleton of the cartilage of the external ear (dimi- nished). ( From Soemmerring.) The skin covering the cartilage of the ear adheres intimately to its unequal surface, less so to ij:s back and circumference. The lower part of the hem-like fold of the helix is formed entirely by it ; also the lobule, as has been already said. The skin of the auricle contains a number of sebaceous follicles, particularly in the concha, and around the entrance of the au- ditory passage. On the tragus is observed, especially in old people, a small tuft of hair, which has been compared to a goat's beard ; whence the name tragus,(Tgayo;, h ireus,) which the Germans trans- late Bock. The antitragus they call Gcgenbock. Ligaments of the ear. Anterior ligament, ( ligumentum auricula anterius ) . — This proceeds from the root of the zygomatic process to the lower and anterior part of the helix, and to the tragus. Posterior ligament, (ligumentum auricula posterius ). — Extends from the outer surface of the mastoid process to the posterior surface of the cartilage of the ear, where the concha runs into the auditory passage. Besides the above ligaments binding the ear to the head, there are others which extend from one point of the car- tilage of the ear to another. Muscles of the ear. — The muscles of the ear fall into two classes : viz. those which, arising from the head, are inserted into the ear, and move it as a whole ; and those which, extend- ing from one part of the cartilage to another, are calculated, were they strong enough, to pro- duce a change in the general form of the auricle. Muscles which move the ear as a whole, or the extrinsic muscles. — The elevator, or superior muscle of the ear, ( M. attollens auriculam s. superior auricula ), is a broad thin muscle, composed of fibres spread out on the upper part of the side of the head. It arises from the middle part of the epicranial aponeuroses, and also from the temporal aponeuroses ; thence, to its insertion into that elevation of the ear-carti- lage on the surface next the head, which cor- responds to the fossa innominata, the fibres be- come more aggregated, so that the muscle is much narrower, but thicker inferiorly than su- periorly. By elevating the upper part of the ORGAN OF HEARING. ear, it will widen and straighten the auditory passage. The retractor or posterior muscles of the ear, ( M. retrahentes auriculam, s. posteriores auri- cula.) These ordinarily consist of three bundles, sometimes only two, which, taking their origin from the mastoid process, run forwards to the cartilage of the ear, into winch they are inserted at the eminence on the back of the concha, corresponding to the commencement of the helix on the other side. In drawing the eai backwaids, these muscles Will dilate and flatten the concha, and widen the entrance to the auditory passage. The anterior muscle of the ear, ( M.uttrahens auriculam s. anterior auricula.,) arises from the zygomatic process, and, in its course backwards to the ear, gradually contracts, untd it ends in a short tendon, which is inserted into the anterior surlace of the helix, immediately above the tragus. It draws the ear forwards. Fig. 255. The cartilage of the left auricle from behind, and the extrinsic muscles ( diminished ). ( From Soemmer- ing). a. m. attollens auriculam ; b. m. anterior auri- culae ; c. d. two m. retrahentes auriculam. Intrinsic muscles of the ear.- — These muscles are very delicate and weak, little adapted to produce any sensible change in the form of the ear. Five are admitted : — The larger muscle of the helix, ( M. helicis major,) arises from the lower and anterior part of the helix, on the outer and anterior surface of which it ascends for about three quarters of an inch, and then is inserted into the helix above the point where the ear becomes free from its attachment to the head. "The smaller muscle of the helix, ( M. helicis minor.) — This lies farther down and more be- hind than the preceding. It begins at the place where the helix rises from the concha, and is inserted into the posterior margin of the ascend- ing portion of the helix. The muscle of the tragus, C m. tragicus). — Of an oblong square form, this muscle covers the outer surface of the tragus, from the lower part to the upper margin of which its fibres run. The muscle of the antitrugus, (m. antitragi- cus). — The fibres of this muscle arise from the outer surface of the antitiagus, and are inserted by a small tendon to which they converge into the lower extremity of the anthehx. Fig. 256. The intrinsic muscles situated on the concave side of the auricle (diminished ). ( From Soemmering ). The transverse muscle of the ear, ( m. trans- versa auricula,) is situated on the back of the ear. It is composed of fasciculi not very dis- tinctly muscular, which run from the dorsum of the concha to the back of the anthelix, and the elevation which corresponds to the navicular fossa. Fig. 257. a. transversus mus- cle ; 6. helix ; c. back of the concha ; d. tra- gus; e. fissure of San- torini. The back of the cartilage of the' external ear and the transversus muscle ( diminished ). ( From Soemmer- ing). B. 'The external auditory passage, (meatus au- ditorius externus s. porus acuslicus; Fr. Le. con- duit audit if ou uuriculaire; Germ. Der Gehor- gang.) — Like the Eustachian tube, the external auditory passage is composed of an osseous portion, and a portion partly cartilaginous and partly membraneous. The osseous portion has been already described as a part of the outer wall of the tympanum; the other portion comes to be noticed here as a continuation of the car- tilage of the auricle. The passage will then be considered as a whole. Cartilaginous and membraneous portion of the external auditory passage, meatus auditoriut cartilugineus-membranaceus. This portion of the auditory passage, about half an inch long, is formed in front and below by cartilage, above ORGAN OF HEARING. 553 and behind by dense fibro-membraneous cellu- lar tissue, in which many cerumiiious glands are imbedded. The plate of cartilage which forms the an- terior and lower wall of this portion of the auditory passage is of a triangular shape with a fissure running through ils base to near the apex. The base is below; the apex above. The base corresponds to the anterior surface of the mas- toid process. One side is attached to the anterior and lower part of the circumference of the outer extremity of the osseous passage, by dense and strong cellular tissue. The other side corresponds to the base of the tragus. The apex or angle formed by the two sides runs into the upper part of the base of the tragus, and corresponds to the root of the zygomatic process. The angle formed by the base, and that side which is attached to the osseous part of the passage, is extended into a broad pointed tongue, which is fixed into the deep and rough depression at the lowest part of the margin of the orifice of the osseous passage. The angle formed by the base and Ihe other side is continued into the concha. The dense fibrous cellular tissue, which completes the passage above and behind, ex- tends from the cartilage of the concha to the upper and posterior part of the margin of the external orifice of the osseous part of the passage. What are called the fissures of Santonni, incisure Suntoriniunte, are: — 1. that fissure extending through the base of the triangular plate of cartilage to near its apex ; and 2. that between the outer margin of the cartilage and the base of the tragus. These fissures are closed by fibrous cellular tissue which, particu- larly over the second fissure, appeared to San- torini to consist of muscular fibres. These fibres have, therefore, received the name of the muscle of the largest fissure, or the muscle of Santorini, m. incisure majuris s. Santorini. IJaller considered their action to be, by ap- proximating the cartilaginous pieces, to shorten the length of the passage. V iewed as a whole, the auditory passage is a canal of an oval calibre. It leads from the auricle to the tympanum, from the cavity of which it is separated by the interposition of the membrana tympani. In front of it lies the joint of the lower jaw, behind is the mastoid process. In the adult its length is about an inch and a quarter, and its direction is at first some- what forwards, then upwards and backwards, and lastly downwards and forwards again. Its louver wall is from one-tenth to one-fifth of an inch longer than the upper. The auditory passage is lined by a continua- tion of the skin of the auricle. This skin be- comes more and more delicate as it approaches the osseous part of the passage, — extremely so where it is continued on the outer surface of the membrana tympani. The skin of the audi- tory passage is covered with fine hairs, and in old persons close to the entrance, hairs like those on the tragus, sometimes of considerable length, are enrooted. The skin of the auditory passage is connected to the subjacent cartilage and bone by rather dense and sparing cellular tissue. The epider- mis readily separates by putrefaction, and may be drawn out like the finger of a glove, the blind end being the part which forms the outer borrowed layer of the membrana tympani. From about a tenth of an inch within the auditory passage to about one-fifth of an inch from the membrana tympani, the lining integu- ment is perforated by numerous small aper- tures, the terminations of the excretory ducts of the glands which secrete the ear-wax. These excretory orifices are most numerous about the middle of the passage, towards the termination of the cartilaginous and membraneous portion. The ceruminous glands, glandules cerumi? non . >* ■/ >' "v ; " ! v. ' ' 1 1 1 * J\ -< The most interesting irregular formation of the malleus is what appears to be connected in some manner with the above described early condition of the malleus and incus. Such cases are related by Hyrtl,* Heusinger,f and Hesselbach.J 2. Of the external ear. — The external ear soon disappears in the animal series. It is the last part of the apparatus of hearing which makes its appearance in the human embryo. It is very subject to irregular deve- lopment. It is only about the middle of the second month that a trace of it can be ob- served. It is at first merely a slight elevation of the skin, broad above, narrow below. In the middle of this elevation is a longitudinal fissure of the same form, which is narrower and at the same time deeper from above downwards. The prominence soon becomes more elevated and thinner at its posterior part, and projects above the surface of the side of the head, from which circumstance the middle depression is a little exposed. At the same time or soon after, the anterior part of the prominence is found divided into two halves by a transverse fissure running forwards; the inferior half is the antitragus, and the supe- rior the commencement of the helix. At the same time this anterior part of the external ear rises also, and the posterior spreads more out. In the third month the anthelix and tragus are developed ; the concha is not yet perfectly dis- tinct; it is only indicated by the middle de- pression. In the fourth and fifth month the hollow of the concha appears, and is completely formed in the sixth. The lobule is the last part which presents itself. The cartilage begins to be formed in the third month, but is developed slowly. To- wards the end of pregnancy, though thicker, harder, and firmer, it is still incomplete. The cartilaginous portion of the auditory passage as well as the auricle is at first pro- portionally much smaller than afterwards. The skin lining the auditory passage is softer and thicker than in the adult, and is covered with a thickly set down. In the foetus the auditory passage is rounder, straighter, and shorter than in the adult. The auricles may not be formed at all, or their development may be so arrested that they shall be represented merely by unshapely folds of skin with or without cartilage, or they may deviate more or less from their usual form, size, and situation. Imperfect formation of the auricle is frequently accompanied by ab- sence or closure of the auditory passage. Pro- fessor Samuel Cooper mentions the case of a child in which there was not the slightest trace either of external ear or auditory passage. * Op. et loc. cit. f Specimen mala; conformationis organorum auditus human! rarissimum et memoratu dignis- simum, cum tvibus tabulis aeri incisis. Jenae, 1824. % Beschreibung der pathologischen Priiparate, welche in der kbniglichen anatomischen Anstalt zu VVurzburg aufbewahit werden. Giessen, 1824. 2 P 562 ORGAN OF HEARING. Sometimes, however, the auditory passage has been found regular though the auricles were wanting. The auditory passage is sometimes found too wide, sometimes too narrow, sometimes too short. Closure of the auditory passage may be either partial or through its whole extent. It is move rarely the effect of disease than of irregular primitive formation. Partial closure may be by an extension of the skin over the mouth of the passage. Authors mention cases of a membraneous septum sometimes deep in the auditory passage and before the membrana tympani, sometimes nearer the entrance of the passage. In monstrous foetuses all the accessory parts of the apparatus of hearing together have been found wanting. II. PARALLEL BETWEEN THE EAR AND THE EYE. A parallel has often been drawn betwixt the ear and the eye. Breschet, in his memoir, already so often cited in the course of this article, compares the perilymph to the aqueous humour, the endolymph to the vitreous hu- mour, and the calcareous concretions to the crystalline body. The comparison which I should institute between the component parts of the ear and the eye is the following: — The osseous labyrinth may be compared to the sclerotica, and the fenestra rotunda, or coch- lear fenestra, to the cornea. To find a part in the eye analogous to the vestibular fenestra, we must first consider that the latter is a yielding part of the otherwise solid wall of the labyrinth ; that through the medium of it, the chain of small bones and their muscles in the tympanum exercise on the soft parts contained in the labyrinthic cavity, a certain degree of tension or compression fitted probably to accommodate in some man- ner the ear to the perception of different degrees of sound. In the case of the eye, the sclerotica,which corresponds to the osseous labyrinth, is thinner and more yielding at the middle of its circumference, (remarkably so in the Greenland seal). From this it has been supposed that the action of the muscles of the eye-ball might by their compression produce a change of shape fitted to accommodate the eye to distances. Hence the vestibular fenestra and middle thin part of the sclerotica might be compared to each other in as far as regards the function which each performs in the eco- nomy of its own organ. However this may be, the vestibular fenestra of the ear and the thin part of the sclerotica correspond to each other as far as can be in relative position ; and if we admit the action just mentioned of the muscles upon the eye-ball, we have, as I shall imme- diately show, their counterparts in the muscles of the small bones of the tympanum. The tympanic scala of the cochlea may be compared to the anterior chamber of the aqueous humour, and the vestibular scala to the posterior chamber. The spiral lamina, considering its vascu- larity and richness in nerves, and its forming a partition between two chambers containing an aqueous humour, may, as I have already said in a former part of this article, be con- sidered the counterpart of the iris, and the helicotrema that of the pupil. The membrane lining the labyrinthic cavity bears the same relation to the latter as the arachnoidea ticuli* does to the sclerotica. The space filled with perilymph, between the osse- ous and membraneous labyrinth, may be con- sidered analogous to that between the sclerotica and choroid. It however communicates with the scalae of the cochlea, the parts analogous to the chambers of the aqueous humour, be- cause there is nothing in the ear to be com- pared to the ciliary ligament. Forming the membraneous labyrinth we find, 1. a delicate cellular tissue supporting the branches of the bloodvessels, and which is sometimes found containing black pigment ; 2. a firm transparent membraneous coat, within which, 3. is a nervous expansion ; 4. the endo- lymph; 5. suspended in the latter the mass of calcareous matter. The cellulo-vascular layer containing pigment, together with the rest of the walls of the membraneous labyrinth, may be compared to the choroid coat of the eye, the nervous expansion to the retina, the endo- lymph to the vitreous humour, and the calca- reous mass to the lens. In the lower animals the cochlea is the first part of the ear-bulb to disappear ; in regard to the eye-ball, the aqueous chambers to which I have compared the scalae of the cochlea, are in like manner the first parts which in the de- preciation of the structure of the eye, in the animal series, disappear, e. g. the eye of the Cephalopodous Mollusca. Is the cochlear nerve the same in function with the vestibular? The vestibular nerve is the special nerve of hearing ; but does not the cochlear nerve perform some function in the economy of the ear analogous to what the ciliary nerves perform in that of the eye ? If an example is required in which the optic nervous filaments enter the eye separately as do the nervous filaments of the ear-bulb, it is to be found in the Cephalopodous Mol- lusca.f As in front of the eyeball there is, or rather would be, if it was not that the eyelids are constantly in contact with the eyeball, a space lined by a mucous membrane, the conjunctiva, so at the peripheral surface of the ear-bulb, there is a space, the tympanic cavity, lined by a mucous membrane also. Moreover, as there is a passage into the nose from the space bounded by the conjunctiva, so does the tym- * See mv figure and description of a horizontal section of the human eye, in Mackenzie's Practical Treatise on Diseases of the Eye. Second Edition. London, 1835. t See a paper " On the Retina of the Cuttle- fish," in the London and Edinburgh Philosophical Magazine for January, 1836. ORGAN OF HEARING. 563 panic cavity communicate with the throat by the Eustachian tube. In the tympanic cavity there is a chain of small bones, articulated to each other and moved by muscles, which serves to produce some change in the state of tension of the soft parts of the ear-bulb ; in the conjunctival space there is nothing analo- gous, although, without pushing the point too far, we might compare the muscles of the eye- ball with those of the ossicles of the tym- panum, both being equally, in fact, outside their respective mucous membranes. In re- gard to the ossicles I would remark that, according to the views of Weber,* they must be reckoned among those which do not belong to the skeleton, and which are of very incon- stant occurrence. Such are the bone of the penis in many animals, the teeth, the ring of bony plates round the front of the sclerotica of the bird's eye, SfC. Apart in the composition of the appendages of the eye analogous to the membrana tym- pani is only to be conceived by supposing the existence of a mediate ankyloblepharon, that is, an irregular membrane stretched between the edges of the eyelids, uniting them toge- ther and closing in the space lined by the con- junctiva, which space would now communi- cate with the exterior, only by the lachrymal canalicules and nasal duct, in the same way that the tympanic cavity communicates with the exterior only by the Eustachian tube. A congenital fissure or total absence of the mem- brana tympani is an irregularity of structure in the ear, which may be compared to what is regular in the eye. A mind accustomed to trace analogies will perceive a resemblance : — to the external auditory passage in that short space at the opening of the eyelids extending from the inner edge of the tarsal margin to the outer ; to the ceruininous glands in the Mei- bomian follicles; and to the hairs at the en- trance of the auditory passage in the eyelashes. The auricle, if it is necessary to look for a part corresponding to it, may be placed in the same category with the eyebrows. Bibliography.— General Works on the Organ of Hearing. Gabriel Fallopius, Observationes Anatomicae. Coloniae, 1562, 8vo. Bartholomeus Eustachius, Epis- tola de organis auditus. In ejus Opusculis Anato- micis. Venetiis, 1563, 4to. pp. 148-164. Volclier Koiter, De auditus instrumento. In ejus extern, et intern, princip. c. h. partium tabulae, &c. Nori- bergae, 1573, fol. pp. 88-105. Hieronymus Fabri- cius ab Aquapendente, Libellus de visione, voce et auditu. Rec. in ejus Opp. a B. S. Albino editis. Lugd. Batav. 1737, fol. Julius Casserius, De vocis aiiditusque organis historia anatomica. Ferrariae, 1600, fol. Et in ejus Pentaestheseion, h. e. de quinque sensibus liber. Francof. 1610, fol. lib. iv. pp. 148-265. Ceecilius Folios, Nova interna; anris delineatio. Venetiis, 1645. 4. Recus. in Bartho- lin! epistolis et in Halleri collect, dissert, anat. vol. iv. p. 365. Jean Mery, Description exacte de l'oreille ; ed. cum Lamy explic. median, des fonc- tions de l'ame. Paris, 1687, 12mo. Guichard Joseph du Verney, Observation sur l'organe de l'ouie, Mem. de Paris, vol. i. p. 395. Ditto, Traite * Hildebrandt's Anatomie, Band. iv. p. 39. de l'organe de l'ouie, contenant la structure, les usages et les maladies de toutes les parties de l'oreille. Paris, 1683-1718, 12mo. Leide, 1731, 8vo. Treatise on the organ of hearing. London, 1737, 8vo. G. C. Schelhammer , De auditu liber unus, &c. Lugd. Batav. 1684, 8vo. Rec. in Man- geti Bibl. anat. torn. ii. A. M. Valsalva, De aure humana tractatus, &c. Genevae, 1716, 4to. Ditto, Opera, h. e. tractatus de aure humana editione hac quarta accuratissime descriptus tabulisque arche- typis exornalus, &c. Omnia recensuit, &c. Joannes Baptista Morgagnus : tomi duo. Venetiis, 1740, 4to. R. Vieussens, Epistola ad Societatem Reg. Lond. missa de organo auditus. Philosophical Transactions, 1699, vol. xxi. p. 370. Ditto, Traite de la structure de l'oreille. Toulouse, 1714, 4to. J. F. Cassebohm, Disp. anat. inaug. de aure interna. Francof. cis Viadr. 1730, 4to. Ditto, Tractatus quatuor anatomici de aure humana, tribus rigura- rum" tabulis illustrati. Halae Magd., 1734, 4to. Ditto, Tractatus quintus de aure humana, cui acce- dit tractatus sextus anatomicus de aure monstri humani c. tribus figurarum tabulis. Halae Magd. 1735, 4to. B. S, Albinus, De aure humana inte- riore. In ejus Academicarum annotationum, lib. iv. Leidae, 1758, 4to. cap. ii. p. 14-15, tab. i. ii. Geoffroy, Dissertations sur l'organe de l'ouie ; 1«. de Phomme ; 2». des reptiles ; 3o. des poissons. Amsterdam, 1778, 8vo. A. Scarpa, Disquisitioncs anatomica; de auditu et olfactu. Ticini et Medio- lani, 1789, fol. c. tab. asn. A. Comparetti, Obser- vationes an itomicas de aure interna comparata, c. tab. iii. aen. Patavii, 4to. The date, 1789, is oij the title-page, but the book did not appear until 1791. C, F. L. Wildberq, Versuch einer anato- misch - physiologisch - pathologischen Abhandlung iibcr die Gehdrwerkzcuge des Menschen. Mit Kup- fern. Jena, 1795. S. T. Suemmerriny, Abbildung- en des menschlichen Hbrorgans. Frankf. a M. 1806, fol. Icones organi auditus humani. Francof. 1806, fol. J. C. Saunders, The anatomy of the human ear, &c. with a treatise on the diseases of that organ, &c. Lond. 1829. C. E. Pohl, Expo- sitio generalis anatomica organi auditus per classes animalium. Accedunt quinque tabula; lithogra- phicae. Vmdobonae, 1818, 4to. T. H. Weber, De aure et auditu hominis et animalium. Lipsiae, 1820. D. De Blainville, Traite de l'organisalion des Animanx, &c. vol. i. Aestheseiologie. Paris, 1822. J, van der Hoeven, Disput. anat. phys. de organo auditus in bomine. Traj. ad Rhen. 1822, 8vo. Expose sommaire des nouvelles rechcrches du Dr. Ribes sur quelques parties de l'oreille in- terne, in Magendie, Journal de Physiologie Experi- mentale, vol. ii. p. 237. A. Fischer, Tractatus anatomico-physiologicus de auditu hominis, cum tribus tabul. aeri incis. Mosquae, 1825, 8vo. J. C. Teule, De l'oreille, essai d'anatomie et de physio- logie precede d'un expose des lois de l'acoustique. Paris, 1828 , 8vo. G. Brescliet, Recherchcs ana- tomiques et physioloques sur l'organe de l'ouie et sur l'audition, dans l'homme et les animaux verte- brcs, 4to. Paris, 1836. Also in Mcmoires de l'Academie Royale de Medecine, torn. v. 3e fasci- cule. Paris, 1836. C. G. Liucke, Das Gehdrorgan in anatomischer, physiologischcr und pathologisch- anatomischer Hinsicht ; also, under the title, Hand- buch der th.eoretiscb.en und praktischen Ohrenheil- kunde. lstr. Band. Leipzig, 1837. Works on particular parts of the organ of hearing. On the labyrinth. — J. G. Brendel, Progr. de au- ditu in apice conchas. Goetting. 1747. Recus. in Halleri Collect, diss. anat. vol. iv. p. 399. Progr. quasdam analecta de concha auris humanae. Goet- tingae, 1747, 4to. ; also in his Opusc. edit. Wris- berg. Goett. 1769, 4to. vol. i. J. G. Zinn, Obser- vationes de vasis subtilioribus oculi et cochlea; auris interna;. Goettinga;, 1753, 4to. D. Cotunni, De aquaeductibus auris humana; interna; anatomica dis- sertatio. Neapoli, 1761, 8vo. Vienna;, 1774, 8vo. Recus. in Sandifort Thesaur. dissert, vol. i. p. 389. P. F. Meckel, Diss, de labyrinthi auris content!!!.. 2 P 2 564 HEARING. Argentorati, 1777, 4to. A. Monro, Three treatises on the brain, the eye, and the ear. Edinb. 1794, tract iii. Hrugnone, Observations anatomico-phy- siologiques sur le labyrinthe de l'oreille. In Me- moires de l'Acad. Imper. des Sciences, litt. et beaux arts de Tinin, pour les ann. 1805-1808. Sciences phys. et mathera. Turin, 1809, pp. 167- 176. XV . Krimer, Chemische Untersuchungen des Labyiinthwassers. In his Physiologische Abhand- lungen. Leipzig, 1820, p. 256. J. G. Ilg, Emige anatomische Beobacbtungen, enthaltend eine Be- richtigung des zeiiherigen Lehre vom Baue der Schnecke des menschlichen Gehbrorgans, nebst einer anatomischen Beschrcibung und Abbildung eines durch ausserordentliche Knochenwucherung selir mekwlircligen Schadels. Prag. 1821, 4to. F. Rosenthal, Ueber den Bau der Spindel in mens- schlichen Ohr. In Meckel's deutscbem Archiv. fur die Physiologie. B. viii. p. 74-78. Huschke, Tau- sende von Krystallen iin Gehbrorgan der Vbgel. In Froriep's Notizen. Bd. xxxiii. 1833. No. 3. 36. Ditto, Ueber Kalkkrystalle im Ohr und anderen Theilen des Fisches. In the Isis of Oken. 1833. Heft. vii. p. 675. Ditto, Berichtigung die Kalk- krystalle im Labyrinth betreffend. In the Isis, 1834. Heft. i. p. 107. Karl Steifemand, Untersuchungen iiber die Ampullen des Gehbrorgans. In Miiller's Archiv. f. Anatoraie, physiologie und wissenschaft- liche Medicin. Jahrg. 1835. Heft. ii. p. 17 1-189, and taf. ii. On the cavity of the tympanum. — D. Santorini, Opp. posth. tab. v. A. Scarpa, De structura fene- stras rotundas auris et de tympano secuudario ana- tomicas observations. Mutinas, 1772. On the membrana tympani. — A. Q. Rivinus, Diss, de auditus vitiis. Lipsias, 1717, 4to. p. 28, et tab. adj. Recus. in Halleii collect, dissert, anat. vol. iv. p. 309. A. F. Walther, Resp. Casp. Bose, Diss, anat. de membrana tympani. Lipsias, 1725, 4to. F. Caldani, Osservazioni sulla membrana del tim- pano e nuove ricerche sulla ellettricita. animate, lette nell' Academia di Scieuzedi Padova. Padova, 1794, 8vo. Everurd Home, On the structure and uses of the membrana tympani of the ear. In Philosophical Transactions, vol. xc. p. i. 1800, p. 1 ; also, On the difference of structure and uses of the human membrana tympani and that of the elephant. In Philos. Trans. 1823, p. i. p. 23. Brugnone, Observations anatomiques sur 1'origine de la mem- brane du tympan et de celle de la caisse. In iWc- moires de l'Acad. des Sciences litterat. et beaux arts de Turin ; pour les ann. x et xi. Scienc. Phys. et Math. 1 Part. Turin, an xii. pp. 1-10. Vest, Ueber die Wittmannsche Trommelfellklappe. In medic. Jahrbucher des oester. Staates. B. v. Wien, 1819, p. 123-133. H. J. Shrupnell, On the form and structure of the membrana tympani. In Lon- don Medical Gazette, vol. x. p. 120. On the ossicles. — P. Manfredi, Novas circa aurem observationes. In Mangeti Bibliothec. anatom. torn. ii. p. 454. J. A. Schmid, Diss, de periosteo ossiculoium auditus ejusque vasculis. Lugd. Bat. 1719, 4to. H. F. Teichmeyer, Diss. sist. vindi- cias quorundam inventorum meorum anatomicorum a Qonnnilis celeberrimis anatomicis in dubium vo- catorum, lo. de tribus ossiculis auditus majoribus, malleo, incnde et stapede ; 2o. de ossiculis auditus minoribus, ovali, semilunari, lenticulari et triangu- lari ; 3o. de foramine tympani. Jenas, 1727, 4io. Rec. in Halleri collect, diss. anat. vol. iv. p. 396. A. Carlisle, The physiology of the stapes, &c. In Philos. Trans. 1805, p. 193. T. W Chevalier, On the ligaments of the human ossicula auditus. In the Medico-Chirurgical Transactions, vol. xiii. p.i. 1825, p. 61. H. J. Shrapnetl, On the structure of the os incus, in Lond. Med. Gaz. vol. xii. p. 171. On the muscles of the ossicles. — Magendie, Sur les organes, qui tendent on relachent la membrane du tympan et la chaine des osselets de l'ouie dans Thomiue et les animaux mammiferes, in Journ. de Physiol, exp. torn. i. p. 341. E. Hagenbach, Dis- quisitiones anatomicas circa musculos auris internas homiuis et mammalium adjectis animadversionibus nonnullis de ganglio auriculari sive otico, cum tab. iv. asri incis. Basilcas, 1833, 4to. Bonnafpnt, Nou- velle exposition des mouvemens de la chaine des osselets de l'ouie. In Journal des Sciences Medi- cales de Montpellier. Prem. ann. torn. ii. livr. iii. 1834, p. 93, 97, and livr. v. p. 175-176. On the Eustachian tube. — J. Senac, Observation sur la trompe d'Eustache. In Mem. de l'Acad. de Paris, 1724. Hist. p. 37, edit. 8. Hist. p. 52. J. Kollner, Ueber den Zweck der Eustachischen Trotnpete. In Reil's Archiv. fur d. Physiologie. Bd. ii. Heft. 1. p. 18. J. D. Herholdt, Eine An- merkung ueber die Physiologie des Gehbrs. Ein Seitenstuck zur Abhandlung des Herrn Kollner. In Reil's Archiv. f. d. Physiologie. Bd. iii. Heft, ii. p. 165. J. Kollner, Priifung des Bemerkungen ueber die Physiologie des Gehbrs von Joh. Dan. Herholdt, in Reil's Archiv. Bd. iv. Heft. i. p. 105. C. Bressa, Ueber den Hauptnutzen der Eustachi- schen Rbhre. Pavia, 1808. Communicated by Meckel, in Reil's Archiv. Bd. viii. p. 67. A. H. Westrumb, Ueber die Bedeutung der Eustachischen Trompete. In Meckel's Archiv. fur Anatomie und Physiologie. Jahrg. 1828, p. 126-143. P. F. A. Lieboldt, Commentatio de usu tubas Eustachianas ex anatome tam humana quam comparata et phas- nomenis pathologicis illustratis. Goeltingas, 1829, 4to. On the external ear.— J. D. Santorini, De aure ex- teriore. In ejus Observat. anatom. Venetiis, 1724, 4to. cap. ii. p. 37. B. S. Albinus, De cartilagine auriculas. V. ejus Annotat. Academ. lib. vi. Leidas, 1764, 4to. cap. vii. p. 55, tab. iv. fig. 1, 2. On the muscles of the external ear. — J. D. Santo - rini, Observ. anatom. cap. i. tab. i, ejusdem tabulas xvii. posthum. ex edit. M. Girardi. Parm. 1775, fol. tab. i. A. F. Walther, Anatome musculorum teneriorum humani corporis repetita. Lipsias, 1731, 4to. with the table of Santorini. On the ear-wax . — Haygarth, in Medical Observa- tions and Inquiries, vol. iv. edit. 2, 1772, p. 198- 205. Berzelius, Lehrbuch der Thierchemie. Dres- den, 1831, 8vo. p. 440. On the comparative anatomy of the ear. — J. Hunter, An account of the organ ot hearing in fishes, in Phil. Trans, and Animal Economy. The works of Scarpa, Comparetti, Monro, Pohl, Weber, and De Blainville, already mentioned. G. R. Treviranus, Ueber den inneren Bau der Schnecke des Ohrs der Vbgel, in Tiedemann und Treviranus Zeitschrift fur Physiologie. B. i. 188-196. C.J. H. Windisch- mann, De penitiore auris in Amphibiis structura. Lipsias, 1831. G. Breschet, Recherches anato- miques et physiologiques sur l'organe de l'audition chez les oiseaux. Paris, 1836, in 8vo. and atlas in fol. Ditto, Sur l'organe de l'Audition chez les Poissons. Paris, 1837. C T. Wharton Jones.) HEARING (in Physiology,) audition ; Lat. auditus; Fr. l'audition, sens de l'ouie; Germ. das Gehor, Gehorsinn. — Of all the senses, that of hearing is the most valuable to man in his social condition, for without it all interchange of ideas through the medium of a spoken language would be impossible. To it indeed, as a distinguished metaphysician has remarked, we are indirectly indebted for the use of verbal language. By the sense of hearing men and animals take cognizance of sounds and distin- guish their varieties, the almost innumerable multitude of which may well excite our admi- ration of the sense. " Who," says the excel- lent Derham, " who but an intelligent Being, what less than an omnipotent and infinitely wise God, could contrive and make such a fine body, such a medium, so susceptible of every impression that the sense of hearing liath occasion HEARING. 565 for, to empower all animals to express their sense and meaning to others ; to make known their fears, their wants, their pains and sorrows in melancholick tones; their joys and pleasures in more harmonious notes; to send their minds at great distances in a short time in loud boations ; or to express their thoughts near at hand with a gentle voice or in secret whispers. And to say no more, who less than the same most wise and indulgent Creator could form such an ceconomy as that of melody and musick is ; that the medium should, as I said, so readily receive every impression of sound, and convey the melodious vibration of every musi- cal string, the harmonious pulses of every animal voice, and of every musical pipe; and the ear be as well adapted and ready to receive all these impressions as the medium to convey them. And lastly, that by means of the curious lodgment and inosculation of the auditory nerves, the orgasms of the spirits should be allayed and perturbations of the mind in a great measure quieted and stilled ; or to express it in the words of the last-cited famous author (Willis), ' that musick should not only affect the fancy with delight, but also give relief to the grief and sadness of the heart ; yea, appease all those turbulent passions which are excited in the breast by an immoderate ferment and fluctuation of the blood.'" Preliminary observations on sound:* — Sound is the result of an impulse of any kind con- veyed by the air to our ears. The analysis of what takes place on the production of various familiar sounds or noises abundantly explains this. If the ear be applied to one extremity of a long beam of timber and a person tap with his finger on the other, the impulse is distinctly perceived by the impression of sound which is conveyed. A fine probe introduced carefully through the meatus externus, and made to impinge upon the membrana tympani, however gently, will occasion the sensation of sound. To produce the sensation, then, of sound, an im- pulse is necessary either of some solid directly upon the membrane of the tympanum itself, or of the air which is always in contact with that membrane. The body by which the sound is produced, denominated by Professor Wheat- stone f a phonic, occasions in the surrounding air vibrations or oscillations, corresponding in number and extent to those which exist in itself; and these vibrations or oscillations being propagated to the organ of hearing, give rise to the sensation. This agitation of the air sur- rounding the body from whence the sound emanates is manifest in numerous instances ; — the report of a cannon, the rushing of waters, the rattling of carriages, which in the crowded tho- roughfares of London communicate their vibra- tions to the walls and floors of the houses and even to the furniture. In the familiar instance * It will be perceived that in the ensuing obser- vations the writer has borrowed largely from Sir John Herschel's admirable essay on sound in the Encyclopedia Metropolitana. He has also to acknowledge his obligations to the article on Acous- tics in Pouillet's Elcmens dc Physique. f Annals of Philosophy, new series, vol. vi. of eliciting sound from a finger-glass partly full of water by rubbing the wetted finger round its brim, the vibrations which this friction excites in the glass are rendered evident by the crispa- tions produced in the water immediately in contact with it. The vibration of the water, as indicated by these crispations, corresponds with that of the glass — the greater the intensity of the sound elicited, the more considerable are the vibrations in the glass, and consequently the more manifest are those of the water, and vice versa. " In musical sounds we may also observe an agitation which is often felt commu- nicating itself to the surrounding bodies. If, for example, we stand under or near a piano- forte when it is sounding', we feel a sensible tremor in the floor of the apartment. If we lay the finger or hand on the instrument or touch any other, such as a violin when it is sounding, or a bell, we feel the same sort of tremor in every part of them; and this is well observed in the case of any glass vessel, such as a tumbler or large cup. If we strike it so as to make it sound, and then touch the mouth of it with the finger, we feel a sensible tremor in the glass; and when this internal agitation is stopped, as it generally is by the contact with the finger, then the sound ceases along with it."* The disturbance produced in the air by a sounding body has been from a very early period illustrated by a reference to the waves formed in still water by a stone falling into it. " Voice," says Vitruvius, " is breath flowing and made sensible to the hearing by striking the air. It moves in infinite circumferences of circles, as when, by throwing a stone into still water, you produce innumerable circles of waves, increasing from the centre and spread- ing outwards, till the boundary of the space or some obstacle prevents their outlines from going further. In the same manner the voice makes its motions in circles. But in water the circles move breadthways upon a level plane; the voice proceeds in breadth, and also successively ascends in height."f That the presence of air is necessary for the production of sound is proved by the experiment first tried by HauksbeeJ and repeated by Biot. A bell was made to ring in the receiver of an air-pump, and in proportion as the air was exhausted it was found that the sound died away, and it again returned as the air was re-admitted. On the other hand, the bell sounded more strongly when the air within the receiver was condensed, and the greater the condensation of the air, the louder was the sound. Any irregular impulse communicated to the air produces a noise, in contradistinction to a musical sound. This latter results from a succession of impulses, which occur at ex- actly equal intervals of time, and which are exactly similar in duration and intensity. When these impulses succeed each other with great rapidity, the sound appears continuous, * Encycl. Britann. art. Acoustics, t Vitruvius de Arch. v. 3, quoted in Whewell's History of the Inductive Sciences. 1 Phil. Trans. 1705. 566 HEARING. in consequence of the duration of the impres- sion upon the auditory nerve. The frequency of repetition necessary for the production of a continued sound from single impulses is, according to Sir J. Herschel, probably not less than sixteen times in a second, though the limit would appear to differ in different ears. We distinguish in musical sounds, 1, the pitch ; 2, the intensity or loudness ; 3, the quality. The pitch of the sound depends on the rapidity with which the vibrations succeed each other, and any two sounds produced by the same number of vibrations or impulses in the same time are said to be in unison. The loudness or intensity depends upon the violence and extent of the primitive impulse. The quality is supposed by Sir J. Herschel to depend on the greater or less abruptness of the impulses, or generally, on the law which regulates the excur- sions of the molecules of air originally set in motion. Sound may be communicated by air, aeri- form fluids, liquids or solids, with variable degrees of velocity. In air at the temperature of 62° Fahr. sound travels at the rate of 1125 feet in a second, or 1090 feet in a second in dry air at the freezing temperature. The velocity with which sound travels is, however, quite independent of its intensity or its tone; sounds of all pitches and of every quality travel with equal speed, as is proved by the fact that distance does not destroy the harmony of a rapid piece of music played by a band. If notes of a different pitch travelled with different velocities, they would not reach the ear in the order in which they were played. Moreover, Biot put it to the test of direct ex- periment ; he caused several tunes to be played on a flute at the end of a pipe 3120 feet long, and found that they could be distinctly heard without the slightest derangement. Neither is the velocity of sound affected by an increase of density in the air. It is, how- ever, greater in warm than in cold air in conse- quence of the greater elasticity of the former. In the different gases much variety has been observed in the velocity of sound ; through car- bonic gas the rate of the velocity is said to be one-third slower than ordinary, but through hy- drogen gas, which is twelve times more elastic than common air, the speed exceeds the usual rate three and a half times. A more striking difference is as regards the intensity of sound or the impression it is capable of producing on our organs of hearing. This varies conside- rably with the increase or diminution in the density of the transmitting gas. By means of a piece of clock-work, which caused a ham- mer to strike at regular intervals, the conduct- ing power of the gas could be estimated, the clock-work being placed in a glass receiver filled with the gas. It was thus that Priestley ascer- tained that in hydrogen the sound was scarcely louder than in vacuo; in carbonic acid and in oxygen it was somewhat louder than in air. Water can transmit sound, as the anatomist would infer must be the case from the fact that fishes are provided with distinct and highly developed organs of hearing. Hauksbee, An- deron, the Abbe" Nollet, and Franklin have abundantly proved this by their experiments. M. Colladon, by means of a tin cylinder three yards long and eight inches in diameter, closed at its lower end but open to the air above, plunged vertically in the water, was enabled to hear the sound of a bell at a distance of about nine miles, and from numerous observations he concluded that the velocity of sound in water at about 46° Fahr. was equal to 4708 feet in the second. Solids convey sound as well as or even better than air or liquids. Elasticity and ho- mogeneousness are the qualities which best adapt solids for the conveyance of sound : hard substances, then, which are the most elastic, conduct sound best. An interesting experiment of Hassenfratz and Gay Lussac, in the quarries of Paris, affords a striking contrast of the relative conducting powers of air and solids. A blow of a hammer against the rock produced two sounds which separated in their progress ; that propagated through the stone arrived almost instantly, while the sound con- veyed by the air lagged behind. A more re- markable experiment was that of Herhold and Rahn, related by Chladni: — a metallic wire 600 feet long was stretched horizontally, and at one end a plate of sonorous metal was attached ; when the plate was slightly struck, a person at the opposite end, holding the wire in his teeth, heard at every blow two distinct sounds, the first transmitted almost simulta- neously by the metal, the other arriving later through the air. Biot, with the assistance of Messrs. Boulard and Malus, concluded the velocity of sound in cast iron at the tempera- ture 51° Fah. to be 11,090 feet in a second. litjiexion of sound. — Sonorous undulations in passing from one medium to another always experience a partial reflexion, and when they encounter a fixed obstacle, they are wholly reflected ; and in both cases the angle of in- cidence is, as in the reflexion of light, equal to the angle of reflexion. Echos are sounds reflected from some ob- stacle which is placed in their way, as the wall of a house, or those of an apartment, or the surface of a rock, or the vaulted roof of a church, &c; and a sound thus reflected may, by meeting another similar obstacle, be again reflected, and thus the echo may be repeated many times in succession, becoming, however, fainter at each repetition till it dies away alto- gether. The phenomena of echos illustrate beautifully the analogy between sound and light. Thus, the reflexion of sound from con- cave and convex surfaces takes place exactly as in the case of light : if a reflecting surface be concave towards an auditor, the sounds re- flected from its several points will converge towards him, exactly as reflected rays of light do ; and he will receive a sound more intense than if the surface were plane, and the more so the nearer it approaches to a sphere con- centric with himself; the contrary is the case if the echoing surface be convex. If the echo of a sound excited at one station be required to be heard most intensely at another, HEARING. 567 the two stations ought to be conjugate foci of the reflecting surface, i. e. such that if the reflecting surface were polished, rays of light diverging from one would be made after re- flexion to converge to the other. Hence, if a vault be in the form of a hollow ellipsoid of revolution, and a speaker be placed in one focus, his words will be heard by an auditor in the other, as if his ears were close to the other's lips. The same will hold good if the vault be composed of twosegments of paraboloids having a common axis, and their concavities turned towards each other; only in this case sounds excited in the focus of one segment will be collected in the focus of the other after two reflexions. The most favourable circumstances for the production of a distinct echo from plane sur- faces is when the auditor is placed between two such exactly half-way. In this situation the sounds reverberated from both will reach him at the same instant, and reinforce each other : if nearer to one surface than the other, the one will reach him sooner than the other, and the echo will be double and confused.* We propose to enquire the part which each portion of the complex auditory apparatus of man performs in the function of hearing. I. Of the internal ear. — The fact that a part, answering precisely to the vestibule, is to be met with in every class of animals in whom an auditory apparatus can be detected, affords a strong presumption that this portion of the labyrinth is the essential part of the organ. Here is the seat of the principal expansion of the auditory nerve upon the saccule and common sinus, which floating in the perilymph communicate, through the medium of that fluid, with the membrane of the fenestra ovalis, and consequently with the air contained in the tym- panum. Any vibrations or oscillations then excited in the membrane of the fenestra ovalis, cannot fail to affect the perilymph to a propor- tional extent, and through it the membranous vestibule. In the simple ear of Crustaceans as well as that of Cephalopods and the lowest Cyclostomous fishes, the sonorous impressions are conveyed directly to the vestibular cavity through the solid material in which that cavity is formed, or, as in some Crustaceans, through the vibration of an external membrane. In the higher organized fishes, too, the labyrinth constitutes the whole of the auditory apparatus, nor has it any kind of opening to or communication with the external air, being lodged in the walls or cavity of the cranium, the sonorous impressions must be conveyed through the solid cranial parietes ; for, in truth, there is no other mode in which they can be conveyed, and we know that solids are even better conductors of sound than either liquids or aerial fluids.f As to the function performed by the otolithes, * Herschel, Encycl. Metrop. t Hunter, Monro, Weber, and Treviranus, how- ever, describe a communication with the exterior in Rays and the Shark by two long canals ; but Scarpa, Bell, and Blainville positively deny that these ducts perform the office of auditory canals, j or the calcareous dust, otokonies, which are found in the sacculus vestibuli of the ears of Cephalopods and Fishes, no satisfactory theory has as yet been offered by any physiologist. Although it is now admitted that similar cal- careous particles exist in the vestibules of all vertebrated animals, still they are only in a rudimental condition when compared with those of fishes ; indeed it seems not unreason- able to suppose that the calcareous dust or otokonie of cartilaginous fishes (the ray or shark for example) is rudimental of the hard, porcellaneous, and artfully formed otolithe of the osseous fishes.* A sort of loose notion seems to prevail, that the presence of this hard body in the vestibule favours the communication of sound, by impinging upon the expansion of the auditory nerve. The following obser- vations of Camper no doubt propagated this idea, if they did not originally give rise to it : " Pour etre convaincfi," says this distinguished physiologist, " qu'un corps plus on moins dur, mais flottant dans une substance gela- tineuse recoit la plus legere commotion ou mouvement exterieur, on n'a qu'a remplir un verre de gelce de corne de cerf, ct y plonger quelque corps, on sentira aux doigts le mouve- ment de ce corps des qu'on remuera le verre, ou qu'on lui donnera un petit choc avec un doigt de l'autre main. Quand on enferme dans une petite vessie quelque corps dur, le moindre mouvement de la vessie fait branler ce corps, qui produit une sensation tres forte sur le doigt qui tient la vessie." f Sir A. Carlisle thinks that the nature of this substance has reference to the habits of the particular class of fishes in which it exists. " Fishes," he says, " are only provided with more simple organs of hearing, ordained to inform them of collisions among rocks and stones, or the rushing of water or moving bodies in that element : and since the collisions of stones or of water are only variable in their magnitude or intensity, fishes are provided with these dense ossicles to repeat the sem- blable acute tones of similarly dense substances, such as rocks, stones, gravel, &c." Again, " There is an especial sac of calcareous pulp given to skates and some other cartilaginous fishes in the place of the dense ossicles, ap- parently intended to respond to the movements of sand and muddy strata on which they are doomed to reside ; and it is remarkable that the sturgeon has its auditory ossicles consisting partly of hard substance and partly of calca- reous pulp." % Weber believes that the otolithes in fishes supply the place of the cochlea which is want- ing in these animals: the auditory nerves being connected with them receive the vibrations * So definite does the form of these otolithes appear to be in osseous fishes, that Cuvier says the osseous fishes may be determined by their otolithes as well as by any other character. t Mem. de l'Acad. des Sciences, an. 1779, and quoted in Scarpa De auditu et olfactu, p. 23. % Quoted from a Mss. Essay on sound, in the Hunterian Catalogue, vol. iii. p. 193. Miiller calls the otolithe " Eine freier solider Schwingungen repcrcutirender Kbrpcr." 568 HEARING. direct from them, or sometimes the otolithes are so placed with reference to the expansion of the vestibular nerve, as to be able to com- press it against the cranium. But in man and those animals in whom, in addition to a more complicated labyrinth, there is also an external auditory passage and tym- panum, it would appear that the sonorous vibrations are conducted in two ways ; first, through the meatus externus and tympanum to the vestibule and semicircular canals ; and, secondly, through the bones of the head di- rectly to the auditory nerve. Sounds pro- ceeding from external bodies, as Weber ob- serves, are conveyed in the former way ; but the oscillations of one's own voice, although they in part find their way by the external pas- sage, are chiefly conducted by the cranial bones; and, as Professor VVheatstone has remarked, those sounds are best heard which are articu- lated most in the mouth, and with that cavity least open, as e, ou, te, kew. Closing both ears by firmly pressing the hands upon them, one's own voice is not heard less distinctly, but on the contrary more loud and clear than when both ears are left open ; and if only one ear be closed, the voice is heard more distinctly and louder in that ear than in the open one.* The observations and experiments of Weber render it very probable that the cochlea is that part of the labyrinth which is more particularly suited to appreciate sounds communicated through the solid case of the head, or, to use his words, that sounds propagated through the bones of the head are heard specially by the cochlea, but that sounds conducted through the external meatus are perceived by the membra- nous vestibule and semicircular canals more easily than by the cochlea. The following con- siderations favour these views. It is an admitted fact in acoustics that sounds are most perfectly conducted by sub- stances of uniform elasticity, and that when propagated from air or water to a solid, or from a solid to air or water, they are conducted much less completely. Now, inasmuch as the cochlea may be regarded as part and parcel of the cranial bones, the sounds which are pro- pagated by these bones would reach the nervous expansion in that portion of the labyrinth by the most direct route; whereas, to affect the re- maining parts of the labyrinth, the sound must be conducted from the bone through the peri- lymph to the membranous vestibule and semi- circular canals. Moreover, when it is con- sidered that the cochlear nerves are disposed in a radiated manner in the lamina spiralis, it will appear evident that the oscillations pro- pagated to the petrous portion of the temporal bone must exert a direct influence on the coch- lear portion of the auditory nerve. One or two experiments with the tuning-fork show not only that the cranial bones do con- duct, but also that sounds, inaudible or im- perfectly audible through the meatus externus, may be distinctly heard when the sounding * E. H. Weber De Auditu in Annotai. Anatom. et Physiolog. Lips. 1834. body is brought into contact with a bone of the cranium or face. When the tuning-fork is put into vibration by striking it against any solid body, if held near the external ear its vibrations are heard distinctly, but let the handle be applied to the teeth or to the superior maxilla, and the sound appears much louder ; or if the fork be held near the ear until the sound has almost died away, and then its handle be ap- plied to the superior maxilla or the teeth, the sound seems greatly to revive and continues for a considerable period, the handle being kept in contact with the bone. When the conducting stem of the sounding tuning fork is placed on any part of the head, if both ears be closed by being covered with the hands, a considerable augmentation of the sound will be observed.* If the sounding- fork be kept in contact with the head for a short time, both ears remaining open, and then one ear be closed, the sound will be greatly augmented in the closed ear, and will appear to be heard exclusively by it. This experiment is more striking if the stem of the tuning-fork be applied to the mastoid process on one side : when both ears remain open, the sound seems to be heard chiefly by the ear in the vicinity of which the stem is placed, but when the opposite ear is closed, it appears as if the sound were transferred from the open to the closed ear ; and if the ear be alternately opened and closed, the sound will alternately appear to be transferred from the one to the other. Similar phenomena may be observed if both ears are closed on the first application of the tuning-fork. The sound is at first heard in the adjacent ear, and either remains in it or is transferred to the opposite one, according as the former remains closed or is opened. Mr. Wheatstone adds that if the meatus and concha of one ear be filled with water, the sound from the tuning-fork will be referred to the cavity containing the water in the same way as when it contained air and was closed by the hand. These phenomena afford obvious examples of the communication of sound through the bones of the head. The augmentation of the sound in the closed ear appears to result, as Mr. Wheatstone explains,f from the recipro- cation of the vibrations by the air contained within the closed cavity, and this explanation is confirmed by the fact that when the meatus is closed by a fibrous substance, such as wool, no increase is obtained. The following rationale may be offered of what occurs when the sound from the tuning-fork is communicated to a closed ear, in accordance with the views of Weber respecting the function of the cochlea. The vibrations of the fork are propagated by the bones of the head to the cochlea, the fluid of which being thus thrown into vibration causes the membrane of the fenestra rotunda to vibrate, * These experiments were first suggested by Professor Wheatstone. — See his experiments on audition in the Journal of the Royal Institution for July 1827. t Loc. cit. HEARING. by which as well as by the vibrations of the bones, the air in the tympanum is made to vibrate, and that cavity being closed the sono- rous vibrations are reflected from its walls so as to give rise to the augmentation of the sound. Autenrieth and Kemer believed the cochlea to be that part of the auditory apparatus by which we perceive what the French call the " timbre" of sounds; that quality, namely, which depends on the nature of the material of which the sounding body is constituted, as well as on its form and size, and in some degree on the manner in which sound is elicited from it; and they considered it the office of the vestibule to convey to the sen- sorium the pitch and strength of sounds. Their opinion as to the function of the cochlea was founded on some experiments as to the extent to which ceitain of the lower animals were affected by particular instruments of music : the results obtained from these experiments, when taken in connexion with certain dif- ferences in the form and other characteristics of the cochlea in those animals, led these authors to the conclusion that " those ani- mals alone seemed to perceive a difference of the ' timbre ' of sounds of pretty uniform pitch and loudness, in whom the cochlea was very long and projected considerably into the cavity of the tympanum, and was not much concealed by the surrounding bony substance. Thus it appeared that a dog (the cochlea of dogs being longer than that of cats), upon hearing a certain note of the clarionet, set up a howl, but seemed in no way affected at hearing the same note from the flute or violin ; but the cat continued undisturbed, although a variety of instruments was sounded in her hearing. A rabbit (in which the cochlea is prominent) ran away at the note C elicited from a glass tumbler or from a string, but remained still when the same note was sounded even more loudly by the flute."* But it is abun- dantly evident that these experiments do not fairly lead to the conclusion which these phy- siologists endeavoured to establish ; for, as Weber has remarked, it is one thing to be dis- agreeably affected by the peculiar tone of a given note in an instrument of music, and another thing to distinguish the timbre of the notes of different musical instruments. As well might we conclude that dogs excel in the power of distinguishing scents and savours, because the smell and taste of spirits of wine seem to be peculiarly disagreeable to them, and they reject instantly, although hungry, any food offered to them with which that has been mixed. It seems evident that the cochlea is an in- dication of a very advanced condition of the organ of hearing ; beyond this we can arrive at no definite conclusion in the present state of * See these experiments quoted at greater length in Weber's paper before referred to. Autenrieth's paper is to be found in Reil's and Autenrieth's Archiv. fur die Physiologie, B. ix. 1809 ; and contains much valuable and highly interesting matter relative to all the parts of the organ of hearing in several of the Mammalia. our knowledge, unless indeed we admit the very general one of Weber, that it is the pri- mary seat of those auditory impressions which are conveyed through the vibrations of the cranial bones. But this view, however pro- bable, and supported by much sound reasoning, throws no light on the object of the peculiar form and mechanism of the cochlea. We must not omit to notice that a portion of the vestibule is regarded by Weber as performing a similar function to that of the cochlea, and on similar grounds. That portion which is known under the name of the sacculus is so adherent to the bony wall of the vestibule, corresponding to ihejbvea hemispheric a, accord- ing to Scarpa, that it cannot be separated without laceration, and consequently it seems to be better adapted to receive the sonorous vibra- tions which are conveyed by the cranial bones. The remaining parts of the labyrinth, namely, the three semicircular canals and the common sinus, are most affected by those sounds which are conveyed through the external meatus : it seems evident at least that they must be more affected than the cochlea from the connexion between the membrana tympani and fenestra ovalis through the chain of tympanic ossi- cles, by which that membrane is brought into direct communication with the perilymph surrounding the membranous labyrinth. On the other hand these parts are badly adapted to receive the impression of vibrations direct from the cranial bones, being separated from the corresponding osseous parts by the peri lymph, and that part of the auditory nerve which is distributed to them, having no con- nexion with the bone. An experiment of Weber illustrates the relation of the perilymph to the membranous labyrinth, and shows that an impulse upon the membrana tympani is capable of affecting it. In some birds, the falcon for example, the semicircular canals are so large, that the membranous canals may be easily seen. If in such a bird one osseous semicircular canal be opened by a small open- ing, care being taken not to injure the mem- branous canal, and then we press the mem- brane of the tympanum inwards, at each com pression we observe the water contained in the bony canal to flow out with a jerk. He there- fore concludes that the sonorous undulations conveyed by the cranial bones are communi- cated more immediately to the nerve of the cochlea, but those conveyed by the external meatus to the nerve of the vestibule. The semicircular canals are remarkable for the constancy of their number, and of their re- lative position with respect to each other, in all animals in whom they are found. They exist in almost all fishes, and in all the other vertebrate classes, and in these they are never less than three in number, two of which are always placed vertically and one horizontally. The opinion that the arrangement of these canals has reference to conveying the sensation of the direction of sounds, I find expressed by Au- tenrieth and Kerner in the paper already re- ferred to. "In no animal," they say, "are these canals ever more or fewer on each side than 570 HEARING. three, which are so situated that they correspond to the three dimensions of a cube, its length, breadth, and depth, and that every sound ar- riving in one of these three directions will always strike one canal at right angles to its axis, and another in its length. The position of these canals is likewise such, that the cor- responding canals of opposite sides cannot be parallel, and that therefore any sound which strikes the head in any given direction affects the semicircular canal of one side much more than the corresponding one of the opposite side, whereby it may be determined whether the sound coming in a straight line (from west to east for example,) has really moved from west to east, or from east to west."* They state that in animals in whom the semicircular canals are highly developed, the power of dis- tinguishing the direction of sounds is marked to a proportionate degree. Thus in the mole, the development of these canals is very con- siderable, and from a simple experiment it appears that this animal readily distinguishes the direction of sounds. A mole was intro- duced into a wide but flat vessel filled with earth, in which he was allowed to burrow, and it was found that the mole could be made to move about by sounding an instrument out- side the vessel ; if the instrument were sounded on one side, the animal would always imme- diately turn to the other, f The fox seemed to distinguish the direction of sounds better than cats : if at the same time, and at opposite sides, the high tones of a little bell and the deep tones of a bass viol were sounded, the fox always turned to the side whence the high notes came. Cats seem to be sensible of the direction of high notes only. When upon a violin, or a flageolet, or upon a glass goblet containing water, high notes were sounded, the cats always turned towards the place whence the sound came, even although the in- strument was concealed from them : on the other hand, when a person seated on the ground sounded the low notes of a bass viol before several cats in a garden, they seemed to seek in all direc- tions for the place of the sounding body, without nitting upon the right one. The cow, the horse, the pig, and the rabbit seemed to mani- fest particularly little sensibility to the direction of sounds. The dog appears to have less power to distinguish the direction of sound than man; his smell seems to assist him, and it is well known that when a dog is called by his master, he commonly runs backwards and forwards for some time before he finds out the right direction. The human semicircular canals greatly exceed in width all others examined by Autenrieth and Kerner, but this excess is more as regards the canals properly so called, but does not apply to the ampullae. Scarpa had * Op. cit. p. 363. t This experiment, however, was repeated by Esser, who assures us that the direction of the movements of the mole was not influenced by the direction of the tones of the instrument. Kastner's Archiv. fur die gesammte Naturlehre, B. 12, s.,56. quoted in Treviranus, Ergchein. und Gesetze des Organischen Lebens. already remarked, that although the canals of oxen and horses were narrower than those of man, the ampullae were scarcely at all smaller than in the human subject. These observers further remarked, in many animals they ex- amined, an inverse ratio between the width of the ampulla and that of the canals ; that the former were wider in proportion as the latter were narrow. In fine, they conclude that the wider the semicircular canals, the size of the animal being taken into account, the greater is the power of distinguishing the direc- tion of sound. Of the lower animals, the first in order as regards this power is the hedge-hog, which, after the human subject, has, relatively to its size, the widest semicircu- lar canals ; we may form some idea of the width of these canals from the fact that in their centre they are nearly as wide as the semicircular canals of the pig, which is so very much larger an animal. Next to the hedge-hog stands the mole, whose canals are, proportionally to the size of the animal, both remarkably wide and long ; they are peculiar also as projecting free (visible without any prepa- tion) into the cavity of the cranium. The mouse and the bat come next, then the fox and the dog,* the rabbit, the cat, the pig, the cow, the horse, and lastly the sheep. Professor Wheatstone advocates the theory that our notions of audible direction depend upon the excitation of those portions of the auditory nerve which belong to the semi- circular canals. He conceives that we dis- tinguish best the direction of those sounds which are sufficiently intense to affect the bones of the head, and that it is from the portion which is transmitted through those bones that our perception of the direction is obtained. Thus, we always find it difficult to tell by the ear the position whence the feeble tones of the (Eolian harp proceed. The three semicircular canals, then, being situated in planes at right angles with each other, are affected by the sound transmitted through the bones of the head with different degrees of intensity accord- ing to the direction in which the sound is trans- mitted ; for instance, if the sound be trans- mitted in the plane of any one canal, the ner- vous matter in that canal will be more strongly acted on than that in either of the other two ; or if it be transmitted in the plane intermediate between the planes of this canal and the ad- jacent one, the relative intensity with which those two canals will be affected will depend upon the direction of the intermediate plane. The direction suggested to the mind will cor- respond with the position of the canal upon which the strongest impression has been made.-t- * The width of the canals in dogs was found to vary in the different races. Autenrieth and Kerner, loc. cit. f Dr. Young thought that the semicircular canals seemed very capable of assisting in the estimation of the acuteness or pitch of a sound by receiving its impression at their opposite ends, and occa- sioning a recurrence of similar effects at different points of their length, according to the different character of the sound ; while the greater or less HEARING. 571 No conclusions can be derived from the experiments of Flourens with respect to the functions of the several parts of the labyrinth. The effects of disease had already sufficiently indicated the relative importance of the dif- ferent parts of the ear, and even to a certain extent of those of the labyrinth. Thus we knew that stoppage or destruction of the ex- ternal parts does no more than impair the sense of hearing, and that so long as the labyrinth remains perfect, or at least the vestibule, the sense is not destroyed. Sound may be con- veyed to the auditory nerve through the bones of the head, as may be proved by the sen- sation of sound produced by the application of a tuning-fork in vibration to the teeth or to some one of the cranial bones. By a parity of reasoning, Flourens having successively de- stroyed the several parts of the ear in pigeons, inferred that the nervous expansion in the ves- tibule was the part of the organ most essential to audition : " that in strictness, it is the only indispensable part, for all the others may be removed; yet if this continue, audition is not destroyed." Partial destruction of the nervous expansion in the vestibule only partially destroys the sense, and complete destruction of this ex- pansion involves total deafness. The vestibule may be laid open without any very considerable alteration in the sense ; but rupture of the semi- circular canals rendered the hearing confused and painful, and was moreover accompanied with a quick and violent tossing of the head.* One can scarcely imagine vivisections less likely to lead to useful results than those which involve the exposure of the deep-seated internal parts of the ear, a dissection which even on the dead subject demands no ordinary skill ; nor can we refrain from expressing our opinion that had M. Flourens never attempted these experiments, physiology would have been none the worse, and our respect for his hu- manity would have been all the greater. II. Of the accessory parts of the organ. — We shall consider in succession the parts which the external ear — the tympanum, its membrane and ossicles, and the Eustachian tube, play in the process of audition. The external ear may be regarded as consist- ing of two parts, the auricle and the meatus auditorius externus. The complete develope- ment of the former is found only in Mammi- ferous animals, and exists pretty generally throughout the class ; with, however, consider- able diversity of form, varying from an almost flat cartilaginous lamella, scarcely at all under the influence of its muscles, to an elongated funnel-shaped ear-trumpet, very moveable and completely at the command of numerous large muscles. Man and the Quadrumana are at one extremity of this scale ; the Solipeds, Rumi- nants, and Cheiroptera at the other. Some, pressure of the stapes must serve to moderate the tension of the fluid within the vestibule, which serves to convey the impression. The cochlea seems to be pretty evidently a micrometer of sound. — See Med. Lit. p. 98. * Conditions do l'Audition in Experiences sur lc Systeme nervcux, p. 49. Par. 1825. however, are devoid of the auricle, as the mole, the zemni-rat, the mole-rat, the seal, the walrus, &c. It is said that those animals which are remarkable for the large developement of the auricle are almost all timid or nocturnal, and consequently require an acute sense of hearing. That the auricle performs the office of an acoustic instrument to collect and reinforce the sounds which fall upon it, cannot be doubted in those cases in which it is large and fully developed, as in the horse, ass, &c. Here, indeed, we see that the animal employs it as we might expect such an instrument would be used ; the open part is directed towards the quarter whence the sound comes, and continues so directed as long as the animal appears to listen. So far, however, from this part being mainly the instrument for enabling the animal to judge of the direction of sound, it appears to me that it cannot be applied to its full use until the direction of the sound has been in some mea- sure determined ; until the hearing-trumpet has been favourably placed with respect to the quarter whence the sound emanates, its value is not fully experienced. If we watch the movements of the auricle of a horse, we shall see that he uses it altogether for concentrating sounds from particular quarters: when he moves it about quickly, it often seems as if he were feeling for sounds coming from certain direc- tions, having already acquired a tolerable notion, if I may so speak, as to what those directions are. Treviranus,* however, thinks that the reinforcement of the sound is not its principal use : " to what end," he asks, " have its various eminences and depressions been formed, if it have no other use than this, and why are these particularly developed in the human ear, which can have little or no in- fluence as an ear-trumpet in increasing the influence of sounds?" He supposes that in the lower animals, but especially in man, the auricle serves more for forming a judgment respecting the direction of sounds than for assisting in hearing. We cannot understand in what way the fixed auricle of man can aid for this purpose, being almost immoveable, and in- deed altogether so for the purposes of collect- ing sonorous undulations from different quar- ters; nor indeed does it appear that the opinion in question of Treviranus is any thing more than a mere hypothesis. A remark of Mr. Gough, the author of a highly interesting paper in the Manchester Memoirs " on the method of judging by the ear of the position of sonorous bodies," offers a strong argument against this notion. He observes that what- ever may be the direction of a sound in the open air, as soon as it enters the auditory pas- sage, it is compelled to follow the course of that duct until it reaches the apparatus in which the sense of hearing resides.f The experimental researches of Savart throw some light upon the function of this part of the auditory apparatus.} These experiments * Loc. cit. B. ii. p. 137. t Manchester Memoirs, New Series, vol. v. X Majeudie's Journal dc Physiologic, torn. iv. 572 HEARING. were suggested by the result of several ob- servations which he made upon the communi- cation of vibrations through the air from a vibrating body to one placed even at a great distance from it, and susceptible of under- going vibrations. The effect is best seen by using a thin membrane, such as very fine paper, carefully stretched in a horizontal position over the mouth of a glass, or of a small delft basin : a thin layer of sand is spread on this, and a glass thrown into vibration by a violin bow is held at a little distance from it ; that the paper immediately begins to vibrate is shewn by the motions excited in the sand, the par- ticles of which arrange themselves into figures, which are sometimes perfectly regular, and which form with so much rapidity that the eye can scarcely follow " the circumstances which accompany the transformation of the thin layer of sand into a greater or less number of lines of repose." By a series of experiments to be hereafter detailed, Savart showed that the tympanic membrane is capable of being thrown into vibrations by the sonorous impulses from a vibrating body communicated to it by the in- terposed air How far the external ear and auditory canal serve to increase these vibrations of the tympanic membrane, he sought to ascer- tain by the following experiments. He formed a conical tube of pasteboard, with a very wide mouth at its base, the opening at the smaller end being closed by a thin paper stretched over it and glued to the margins of the open- ing. This tube is placed resting on its base, the membrane being upwards and per- fectly horizontal, so that a layer of sand may be spread over it. When a vibrating glass is brought near and parallel to the upper surface of this membrane, it immediately begins to vibrate, and the grains of sand are tossed about but raised but very slightly from the surface. If, however, the vibrating glass be placed near the base or the wide and open extremity of the tube, the vibrations of the membrane will be found to be much more manifest, and the ex- cursions of the grains of sand so considerable, that they are often raised to a height of three or four centimetres ; so that there is a manifest difference in the influence produced upon the membrane by the sonorous undulations excited in the air according as they impinge upon the external surface of the membrane or upon that which is turned towards the interior of the tube. This phenomenon, Savart adds, may depend upon two causes, namely, upon the concen- tration of the sonorous undulations by the tube, or upon the communication of motion to the parietes of the tube, which again would com- municate it to the membrane. With a view to ascertain which of these causes was the effective one, a second conical tube, open at both ends, was held with its narrow extremity a little above and corresponding to the narrow extremity of the former one, but so that there was no contact between them. If now the glass is made to vibrate successively at the large orifices of the two tubes, it will be found that when placed at the orifice of the tube to which the membrane is attached, the oscil- lations of that membrane are considerably greater than when the aerial undulations reach it through the other tube. Whence it may be inferred that in all probability the external ear and auditory canal have, besides any influence they may exert in modifying the movements of the particles of the air, the additional function of presenting a large surface to the aerial un- dulations, consequently to enter into vibration under their influence, and thus to contribute to increase the excursions of the vibrating pd^ts of the membrane with which they are imme- diately in contact; the auricle, by the variety of the direction and the inclination of its sur- faces to one another, can always present to the air a certain number of parts, whose direction is normal (at right angles with) to that of the molecular movement of that fluid. We get a general notion of the value of this external part of the auditory apparatus in col- lecting and directing the sonorous undulations, from the assistance often derived in hearing from increasing the concavity of the external ear by placing the hand behind it, so as to draw it forward and shorten it by pressure at its upper and lower part; by the dulness of hearing which it is said follows the loss of the auricle, and from the fact, so stated, that the seal and walrus are extremely dull of hearing. As regards the loss of the auricle, it is said by Kerner that this loss is followed by the greatest dulness of hearing in those animals in whom the osseous meatus is wanting. In a cat, from whom the right ear was cut close to the skull, after the wound had healed without any stoppage of the meatus, there was a re- markable disposition always to keep its head turned so as to be ready to receive sounds with the left ear, and this continued even after the tympanic membrane of the opposite side had been frequently perforated, that of the right side remaining whole ; and when the left ear was stopped (although the right tympanic mem- brane was sound, and the only injury on that side was the removal of the auricle,) a total deaf- ness was manifested except to the loudest and clearest sounds. The tympanum and its contents. — We have already stated that Savart had demonstrated that the membrana tympani is thrown into vibrations by undulations of the air excited by a sonorous body. This he demonstrated ex- perimentally upon the membrana tympani itself. The temporal bone having been sepa- rated, he sawed away the osseous meatus so as to expose the membrane on a level with the rest of the bone, and when it was suf- ficiently dry, he covered it with a thin layer of sand. A vibrating glass held parallel and very near to the surface of the membrane occasioned a slight movement of the grains of sand ; but owing to the slight extent and the shape of the membrane, it was impossible to determine the existence of any nodal line. In a second experiment, the cavity of the tym- panum was opened, so as to expose the ossi- cles of the ear and their muscles ; and it was observed that when the internus mallei muscle HEARING. 573 acted and rendered the membrane tense, it was much more difficult to produce manifest move- ments in the grains of sand ; thus affording much reason to suppose the tensor tympani muscle is analogous in its use to the iris, and destined to preserve the organ from too strong impressions. This experiment can be best tried on the membrana tympani of the calf. In imitation of the mechanism by which the tension of the membrana tympani is effected, and with a view to determine more decisively the effects produced by variation of the tension of that membrane, Savart constructed a conical tube (fig. 262), with its apex truncated and co- Fig. 262. vered by a layer of very m I thin paper {rri), which ( was glued to the edge of / ^~J~~Z\f the opening. A little / \ wooden lever (I I), intro- / \ duced through an open- / \ ing in the side of the /..- -A tube, and resting on the L, A lower margin of this \ opening (c) as a fulcrum, was used to vary the tension of the membrane, one of its extremities being applied to the under surface of the membrane. It is evident that, by depressing the extremity of the lever that was external to the tube, the inner one would be raised, and thus the membrane stretched to a greater or less degree according to the force used ; on the other hand, by ele- vating the outer extremity, the inner one was separated from the membrane, which was ac- cordingly restored to its original tension. This little lever was employed in imitation of the handle of the malleus, which under the in- fluence of its muscles causes the variation in the tension of the membrana tympani. The artificial tympanic membrane then having been covered with a layer of sand, it was found that, under the influence of a vibrating glass, used as in the former experiments, a manifest dif- ference was produced in the movements of the grains of sand, by increasing the tension of the paper; the greater the tension, the less the height to which the grains of sand were raised ; and these movements were most extensive when the lever was withdrawn from contact, and the membrane left to itself. From these experiments Savart concludes that the membrana tympani may be considered as a body thrown into vibration by the air, and always executing vibrations equal in num- ber to those of the sonorous body which gave rise to the oscillations of the air. But what is the condition of the ossicles of the tympanum whilst the membrane is thus in vibration? The result of the following experiment affords a clue to the answer of this question. To a membrane stretched over a vessel, as in fig. 263, a piece of wood (a 6) uniform in thick- ness is attached, so that the adherent part shall extend from the circumference to the centre of the membrane, while the free portion may project beyond the circumference. When a vibrating glass is brought near this mem- brane, very regular figures are produced, which Fig. 263. however are modified by the presence of the piece of wood, and the vibrations of the mem- brane are communicated to the piece of wood, on which likewise regular figures may be pro- duced. The more extensive the membrane, the longer and thicker may be the piece of wood in which it can excite oscillations, and Savart states that, with membranes of a considerable diameter, he has produced regular vibrations in rods of glass of large dimensions. The oscillations of the piece of wood are much more distinct when the adherent portion is thinned down, as in c d, jig. 264, by which it Fig. 264. seems, as it were, more completely identified with the membrane, and consequently the oscillations of this latter are communicated di- rectly to the thinned portion of the wood, and thence extended to the thick portion a : sand spread upon a will exhibit active movements, and will produce very distinct nodal lines. Thus it may be inferred that the malleus participates in the oscillations of the tympanic membrane ; and these vibrations are propagated to the incus and stapes, and thus to the membrane of the fenestra ovalis. The chain of ossicles then evi- dently performs the office of a conductor of oscillations from the membrana tympani to the membrane of the fenestra ovalis ; but the mal- leus likewise has the important function under the influence of its muscles of regulating the tension of the tympanic membrane ; and to allow of the changes in the position of this bone necessary for that purpose, we find it articulated with the incus by a distinct di- arthrodial joint, and between this latter bone again and the stapes there exists another and a similar joint. This mobility then of the chain of bones, and the muscular apparatus of the malleus and stapes are totally irrespec- tive of the conducting office of the bones, but have reference to the regulation of the tension of the membrane of the tympanum as well as of that of the fenestra ovalis.* We have already seen how the muscle of * The experiments of Savart above detailed have been several times carefully repeated by me with results precisely similar, 574 HEARING. the malleus regulates the membrana tympani, increases its tension, and thus limits the extent of the excursions of its vibrations. The con- traction of the stapedius muscle causes the base of the stapes to compress the membrane of the fenestra ovalis to a greater or less extent, so that the degree of tension of that membrane depends on the condition of this muscle. Compression exerted upon the membrane of the fenestra ovalis extends to the perilymph and through it is propagated to the membrane of the fenestra rotunda, and in this way the same apparatus which regulates the tension of the membrane of the fenestra ovalis performs that office for that of the fenestra rotunda, and Savart has devised a little apparatus which very prettily illustrates the manner in which this may take place. In a disc of wood (« b, fig. 265) of a sufficient Fig. 265. thickness, he hoi- ^ lows out two ca- vities, o and r, f r \ which commu- f ( o \r."=_n— J J nicate at their i J bottoms with & each other by a ^ narrow canal (c) ■ hollowed in the wood, but not open on its sur- face ; a thin membrane is extended over each of the cavities. Thus, the air contained in these cavities may pass easily from one to the other, and may always maintain the same degree of elastic tension in both. If, then, a vibrating glass be brought .near the mem- brane r covered with a layer of sand, it will be found to enter freely into vibration, as evinced by the active movements of the grains of sand. If now pressure be made with the finger on o, r will become convex in propor- tion as o is rendered concave by the pressure, and when in this state, the movements of the sand will be much less considerable than be- fore, presenting an effect precisely similar to that produced on the tympanic membrane by an increase of tension. Thus, the extent of the excursions of the vibrations of the mem- brane r is limited by the pressure exerted upon o, and as the membranes of the two fenestras are related to each other in an analogous man- ner, we may argue that pressure upon the larger one, that of the fenestra ovalis, will occasion tension of the smaller, that of the fenestra rotunda, thereby limiting the extent of the excursions of its vibrations. Moreover it appears, upon reference to the anatomy of these parts, (see fig.252, p. 550,) that the only muscles which have been satisfactorily demonstrated are tensors of the tympanum ; and that at whatever extremity of the chain of ossicles muscular effort be first exerted, a correspond- ing effect will be produced at the other ; that when the stapedius muscle acts, the malleus is thrown into a position favourable to the tension of the membrana tympani, and, on the other hand, the contraction of the internus mallei depresses the stapes, and consequently in- creases the tension of the membranes of the two fenestra. The cessation of muscular action restores all three membranes to their original laxity, nor does it appear that they admit of any further degree of relaxation through the influence of any vital process. The incus forms a bond of connexion between the two other bones, and its motions depend entirely upon theirs in consequence of its articulation with both, while from the fixedness of its con- nexion with the mastoid cells, as well as its intermediate position, and its not having any muscles inserted into it, it is obvious that its motions must be much more limited than those of the other bones. Its use seems to be to complete the chain in such a way, that by reason of its double articulation with the mal- leus on the one hand and the stapes on the other, the tension of the tympanic membranes may be regulated without any sudden or vio- lent motion, which could scarcely be avoided were the conductor between the membranes of the tympanum and fenestra ovalis one piece of bone. But whence the necessity of at all adding to the ear this complex apparatus of tympanum and tympanic membrane, and why might not the sonorous impressions have been made di- rectly upon the membranes which close the openings to the labyrinth ? Upon this point Savart has offered a conjecture which seems to afford the most probable explanation as to the true object of these parts. If the membranes of the fenestra, he says, had been in imme- diate contact with the atmosphere, their elastic state would have been constantly undergoing changes, under the influence of the vicissitudes of temperature of the air, a circumstance which would, in all probability, impair the power of the organ in detecting differences of sounds. He presumes therefore that the membrana tym- pani prevents this contact of the atmosphere with the membranes of the labyrinth, and that the cavity of the tympanum and the mastoid cells form a kind of receptacle in which the air, which finds its way into the tympanum through the Eustachian tube, acquires the con- stant temperature of the body, and establishes in front of the openings of the labyrinth a sort of atmosphere proper to themselves, the tem- perature of which does not vary. This same acute observer remarks that the size of the membrana tympani in all proba- bility, in the different species of animals, exerts much influence upon the number of sounds which they can perceive, and at the same time upon the limits at which those sounds begin or cease to be audible. Were the tympanic membrane in man of greater size than it is, there is no doubt that instead of beginning to hear sounds which result from about thirty vibrations in a second, we should be able to hear only sounds of a higher pitch. Moreover it may be reasonably presumed that animals who have the membrana tympani much larger than that of man, hear much graver sounds than those which result from thirty vibrations in a second ; and, on the other hand, there must be other animals who hear very acute sourds only. Even in the human species, we observe in HEARING. 575 different individuals a similar variation in the limits of sensibility to sounds, that is, we find, in the words of Dr. Wollaston, that " an ear which would be considered as perfect with regard to the generality of sounds, may at the same time be completely insensible to such as are at one or the other extremity of the scale of musical notes, the hearing or not hearing of which seems to depend wholly on the pitch or frequency of vibration constituting the note, and not upon the intensity or loudness of the noise."* And we owe to this distinguished man the knowledge of the interesting fact, that an insensibility of the ear to low sounds may be artificially induced, by exhausting the cavity of the tympanum to a great degree. This may be effected by forcibly attempting to take breath by expansion of the chest, the mouth and nose being kept shut ; after one or two attempts, the pressure of the external air is strongly felt upon the membrana tympani, which is thus from the external pressure thrown into a state of considerable tension. An ear in this state becomes insensible to grave tones, without losing in any degree the perception of more acute ones. This induced defective state of the ear, from exhaustion of the tympanum, may even be preserved for some time without the continued effort of inspiration and without even stopping the breath, and may in an in- stant be removed by the act of swallowing. In repeating this experiment as I sit writing at my desk, I perceive that a great degree of stillness ensues immediately the sensation of pressure upon the tympanic membrane is felt, owing no doubt to the low rumbling noise of the waggons and carriages in the street being imperfectly audible. A similar observation was made by Dr. Wollaston : " If I strike the table before me with the end of my linger," he says, " the whole board sounds with a deep dull note. If I strike it with my nail, there is also at the same time a sharp sound pro- duced by quicker vibrations of parts around the point of contact. When the ear is ex- hausted, it hears only the latter sound, without perceiving in any degree the deeper note of the whole table. In the same manner, in listening to the sound of a carriage the deeper rumbling noise of the body is no longer heard by an exhausted ear; but the rattle of a chain or screw remains at least as audible as before exhaustion." Dr. Wollaston refers to the cu- rious effect produced by trying this experiment at a concert : " none of the sharper sounds are lost, but by the suppression of a great mass of louder sounds the shriller ones are so much the more distinctly perceived, even to the rat- tling of the keys of a bad instrument, or scraping of catgut unskilfully touched." Ano- ther very interesting circumstance connected with this subject is the production of the same condition of the tympanum by the sudden in- crease of external pressure as well as by the decrease of that within, as occurs in the diving- bell as soon as it touches the water, the pres- * Wollaston on Sounds inaudible by certain Ears. Phil. Trans. 1820. sure of which, according to Wollaston, upon the included air closes the Eustachian tube, and in proportion to the descent occasions a degree of tension on the tympanum, that becomes distressing to persons who have not learned to obviate this inconvenience." From one opportunity which I had of de- scending in the diving-bell now exhibiting at the Polytechnic Institution in Regent-street, I ex- perienced this sensation very strongly, and exactly as Dr. Wollaston describes it. The first effect of the pressure on the tympanic membrane was the production of a crackling noise, which was immediately succeeded by a painful sense of pressure in both ears ; but this is immediately relieved by the act of swallow- ing ; it soon however recurs, and may be in a like manner again relieved. I had no means of judging exactly as to the limits of audition ; but I distinctly observed in conversation with those who descended with me, that grave tones were those least distinctly heard ; the grave tones of my own voice also were less distinct as well as the low notes in whistling. In such cases then it would appear that from the strong compression exerted on the mem- brana tympani, that membrane cannot vibrate in unison with tones which result from a small number of vibrations. On the other hand we may infer, from Dr. Wollaston's observations, that " human hearing, in general, is more con- fined than is generally supposed with regard to its perception of very acute sounds, and has probably in every instance some definite limit at no great distance beyond the sounds ordi- narily heard." The ordinary range of human hearing comprised between the lowest notes of the organ and the highest known cry of insects, includes, according to Wollaston, more than nine octaves, the whole of which are distinctly perceptible by most ears. Dr. Wollaston has, however, related some cases in which the range was much less, and limited as regards the per- ception of high notes ; in one case, the sense of hearing terminated at a note four octaves above the middle E of the piano-forte; this note he appeared to hear rather imperfectly, but the F above it was inaudible, although his hearing in other respects was as perfect as that of ordinary ears ; another case was that of a lady who could never hear the chirping of the gryllus campestris; and in a third case the limit was so low that the chirping of the com- mon house-sparrow could not be heard. Dr. Wollaston supposes that inability to hear the piercing squeak of a bat is not very rare, as he met with several instances of persons not aware of such a sound. The opinion prevailed for a long time that rupture or destruction of the membrana tym- pani is necessarily followed by the loss of the sense. But Sir A. Cooper proved distinctly that not only was hearing not destroyed, but that in some cases of deafness it might be punctured with considerable benefit to the patient.* The most frequent cause of destruc- tion of the tympanum is otitis, and provided * Phil. Trans, for 1800 and 1801. 576 HEARING. the suppurative process does not extend so far as to destroy the stapes, the hearing is only impaired; but should that bone and its attached membrane suffer, then a total deafness is the consequence. In one case, related by Sir A. Cooper, the membrana tympani was entirely destroyed on the left side, and partially so on the right, yet this gentleman, if his attention were excited, was capable, when in company, of hearing whatever was said in the usual tone of conversation, but it was remarkable that he heard better with the left ear than with the right, although in the former there were no traces of a membrana tympani. He could not hear from as great a distance as others, and he stated that, in a voyage he had made to the East Indies, while others, when ships were hailed at sea, could catch words with accuracy, his organ of hearing received only an indistinct impression. His musical ear was not impaired, " for he played well on the flute and had fre- quently boine a part in a concert.'' The ex- ternal ear too had acquired a considerable degree of mobility under the direction of the will, so that it could at pleasure be raised or drawn backwards, and this motion was ob- served to take place whenever the attention was directed to sounds not very distinctly audible. The Eustachian tube evidently performs a two-fold office : — it is the passage for the en- trance of air into the tympanic cavity from the throat, thus affording a provision for keeping that cavity constantly full of air in order to allow of the free vibration of the membranes as well as of the chain of bones ; and it seems obvious that the tube communicates with the throat in order that the air introduced through it shall have acquired the temperature of the body. It likewise affords an outlet for the es- cape of such sonorous undulations as do not impinge upon the labyrinthic wall of the tym- panum, which, were there no such communica- tion with the external air, would cause an echo, and in this respect it performs a function si- milar to that of the mastoid cells. The neces- sity of such a provision as is afforded by the first office which the Eustachian tube performs, is manifest from the frequency of deafness re- sulting from a stoppage either in the tube or at its extremity. Bressa supposed that the Eus- tachian lube conducted the sonorous impulses excited by one's own voice from the cavity of the mouth to the labyrinth ;* but the incor- * Reil and Autenrieth, Archiv. fiir die Physiolo- gie, B. viii. This was a modification of an opinion expressed by Boerhaave, viz., that those sounds from without which entered the mouth were conveyed to the labyrinth through the Eustachian tube. An English physiologist advocates the opinion that some sounds are conveyed through the Eustachian tube, and particularly as he supposes in the Cetacea, from the great development of that tube in these animals compared with the external auditory pas- sage, and the erroneous notion propagated by Home that the malleus had no connexion with the tym- panum, but now disproved by the careful exami- nation of Professor Owen. See Fletcher's Phy- siology, and Owen's Edition of Hunter's Animal Economy. rectness of this notion is abundantly proved by the fact that persons who labour under obstruc- tion of this tube can hear their own voices plainly enough, while they are deaf to those of others. Moreover, if we introduce into the mouth a watch or a vibrating tuning fork, care being taken that they do not touch any of the walls of the mouth, they are heard gradually less distinctly as they are approximated to the Eustachian tube ; indeed when held far back in the mouth they are totally inaudible. In some birds the air of the tympanum finds its way not only into the mastoid cells, but also between the two tables of the skull, as in the owl and in singing birds. The arrangement of the osseous structure corresponding to the diploe is exceedingly beautiful in the canary, in which I have examined it. The two tables seem as it were connected by very fine and nu- merous bony pillars, the extremities of which are attached to each table ; cells freely commu- nicating with each other surround these pillars every where, and the air from the tympanum thus traverses the whole of this cellular struc- ture. The superfluous sonorous undulations find their way into these cells, and being re- peatedly reflected from their parietes become greatly weakened, so that they can exert no fur- ther influence upon the hearing. Functions of the nerves. — The nervous ap- paratus connected with the organ of hearing- consists of the nerve which receives the sono- rous impressions, and of other nerves which are connected with the mechanism of the organ. That the portio mollis of the seventh pair an- swers to the former office, anatomy alone abund- antly proves. With respect to the latter nerves some few remarks seem necessary. The mus- cular apparatus of the tympanic ossicles receives its nerves partly from the facial and partly from the otic ganglion, thus exhibiting an analogous arrangement to that of the muscular structure of the iris. Such an analogy renders it ex- tremely probable that the actions of the muscles of the ossicles are excited in a similar way to that in which the iris is prompted to act. The stimulus of sound conveyed to that portion of the nervous centre with which it is connected, excites by reflection the motor power of the facial nerve, which, through its connexion di- rect or indirect with the muscles of the ossicles, causes them to act, and the action is in propor- tion to the intensity of the sound, inasmuch as the more tense the membrane of the tympanum, the less will be the excursions of its vibrations ; as in the iris the more intense the light, the more contracted will the pupil be. It is im- possible in the present state of our knowledge to say what is the office of the chorda tympani, or whether indeed it has any office in connexion with hearing; but we may easily conceive that from its connexion with the facial, an irritation of it may excite that nerve. Equally ignorant are we of the function of the tympanic anas- tomosis. I shall conclude with the following brief summary of the present state of our knowledge respecting the functions of the several portions of the organ of hearing. HEART. 577 1. The vestibule is the essential part of the organ. It detects the presence and intensity of sound, and especially of those sounds con- veyed through the external ear and tympanum. 2. The cochlea, lying in immediate connec- tion with the bone, receives those sounds which are propagated through the bones of the head. According to Kerner it is the medium of the perception of the timbre or quality of sounds.* 3. Of the function of the semicircular canals we know nothing. That they aid in forming a judgment of the direction of sounds is conjec- tured by Autenrieth and Kerner, and more re- cently by Wheatstone. 4. The tympanum and its membrane render the internal ear independent of atmospheric vicissitudes, and the former affords a non-reci- procating cavity for the free vibration of the latter, as well as of the chain of ossicles. 5. The chain of ossicles acts as a conductor of vibrations from the membrana tympani to the fenestra ovalis, and under the influence of the muscles regulates the tension of the mem- brana tympani, as well a? the membrane of the fenestra rotunda, so as to protect the ear against the effects of sounds of great intensity. 6. The external ear and meatus are con- ductors of vibrations ; the former in some de- gree collects them as a hearing-trumpet would do, and probably assists in enabling us to judge of the direction of sounds. f (R. B. Todd.) HEART (in anatomy). G Lat. cor; Fr. caur ; Germ. Herz ; Ital. cuore. The movement of nutritious juices through the texture or textures of which an organized body is composed, is a fundamental law in Physio- logy. In proportion as the vital actions become more complex and energetic, the more a rapid and certain circulation of these fluids, which is intimately connected with this condition, becomes indispensable, and for this purpose we have a pulsatory sac or sacs, called hearts, superadded to the circulatory apparatus. Ano- ther invariable concomitant of this energetic manifestation of the vital phenomena is the more perfect exposure of the nutritious fluids to the atmospheric air, and this, combined with * Muller, who seems to regard the cochlea as an apparatus for distinguishing the pitch of notes, accounts for its peculiar form thus: — He supposes it an organ in which the separate parts of the nerve may he exposed to excitation; for this purpose all the finest fibres of the nerve lie exposed to the in- fluence of the sound-conducting medium, and that it has assumed the spiral form in order that the nerves may be arranged in the most convenient manner and within the smallest space. SeehisFrag- ment on the sense of hearing appended to his work, Zur vergleichenden Physiologie des Gesichtssinnes. t Much remains to be done to determine the true means by which we judge of the direction of sound. The reader who may be interested on the subject will find some valuable observations and experi- ments in Autenrieth and Kerner's paper already quoted, Mr. Gough's paper in the Manchester Memoirs, vol. v., new series, and one by Venturi in Voigt's Magazin f. d. Neueste aus der Physik. Mr. Wheatstone's views are very briefly stated in Dr. Elliotson's Physiology. vol. ir. the dissimilar media in which different animals live and move, necessitates very important modifications in the number, position, and structure of these pulsatory sacs. These hearts were until lately supposed to be exclusively confined to the sanguiferous vessels, but Muller and Panizza have discovered distinct pulsating sacs placed upon the lymphatic vessels in several of the reptile tribe, and these may be considered lymphatic hearts. In the lowest organized plants, as the Fungi, Alga;, &c. and in the lower classes of animals, as the Polypi, Actiniae, and a great part of the intestinal worms, the nutritious fluids are trans- mitted through their substance without any distinct canals or tubes ; while in the higher classes of plants, and in the Medusa, &c. among animals, vessels are present, but these are unprovided with any pulsatory cavities. In the articulated animals generally, the vessels are still without any pulsatory cavities ; but to make up for the deficiency, the dorsal vessel itself has a distinct movement of contraction and relaxation. Various pulsatory dilatations are placed upon the vascular system of the common worm ( Lumbricus terrestris ) ; one or two upon the vascular system of the Holo- thuria ; and one in the Talpa cristata, where the dorsal vessel is reflected upon itself at the posterior extremity of the body to become con- tinuous with an analogous ventral vessel ; all of which may be considered as rudimentary hearts. As we rise in the scale of animals, we find that the heart consists of two distinct portions — of a stronger and more muscular cavity called a ventricle, and of a weaker and less muscular cavity called an auricle. The latter not only serves as a kind of reservoir to the former, but also, by the contraction of its muscular fibres, drives the blood into it. This heart is placed within a sac or pericardium, and possesses valves to prevent the regurgitation of the blood from the ventricle into the auricle, and from the aorta back again into the ventricle. This may be considered as a perfect single heart. This single heart in some of the Mollusca and in Fishes which have a double circulation, propels the blood not only through the lungs, but also through the body. In the Batrachian Reptiles, as in the Frog, though the circulation is single, the heart becomes more complicated ; for instead of a single auricle we have two, one of which receives the blood returning from the respiratory apparatus, the other receives the venous blood of the body. The pulmonic and systemic circulations are here separated as far as the auricles are concerned ; but a single ventricle in which the venous and arterialized blood are intermixed, still continues to propel the sanguineous current both through the lungs and through the body. In the Ophidia or ser- pent tribe the heart possesses the same number of cavities as in the Batrachian Reptiles ; but we have a still nearer approach to the double circulation in the presence of a rudimentary septum ventriculorum. In some of the Sauria, as the Crocodile, the ventricle is divided by partitions into distinct chambers, which never- 2 Q 578 HEART. theloss communicate freely with each other. It would appear, however, from Meckel's descrip- tion, that the ventricle is divided by a complete septum into two separate and distinct chambers in the Crocodilus Lucius. In the Mammalia and Birds, where no intermixture of the venous and arterialized blood takes place, but where all the blood sent along the aorta has been pre- viously subjected freely to the influence of the atmospheric air, we find two distinct hearts, which in the adult have no communication with each other; one the respiratory heart for the transmission of the blood through the lungs, the other the systemic heart for the transmission of the arterialized blood through all the textures of the body. These are not placed separate from each other, as in some of the Mollusca, which with a double circulation have an aquatic respiration, but are in juxta-position, and in fact many of the muscular fibres are common to both. Human Heart ( normal anatomy ). Position. — The heart in the human species is lodged within the cavity of the thorax, occu- pies the middle mediastinum, and is enclosed in a fibro-serous capsule called pericardium. It is placed obliquely from above downwards and from behind forwards, in front of the spine and behind the sternum. The apex is directed downwards, forwards, and to the left side, pro- jects into the notch on the anterior margin of the left lung, and in the quiescent state of the organ corresponds to the posterior surface of the cartilage of the sixth rib. The base looks upwards, backwards, and to the right side ; is separated from the anterior part of the spine by the pericardium, oesophagus, aorta, and other parts which lie in the posterior mediastinum ; and extends from about the fourth to the eighth dorsal vertebra. Its right margin rests upon the upper surface of the cordiform tendon of the diaphragm, by which it is separated from the stomach and liver; its left margin, which is more vertical, looks upwards and to the left side, and occupies an excavation on the inner surface of the left lung. Its posterior or flat surface rests partly upon the cordiform tendon of the diaphragm, having the pericardium inter- posed between them, and partly upon the inner concave surface of the left lung.* Its position corresponds to the union of the superior third of the body with the two inferior thirds. The lungs overlap the lateral, and part (rarely the whole) of the anterior portion of the heart, leaving only in general about an inch and a half or two square inches of the anterior surface of the right ventricle uncovered by the lung. It is of importance to remember this fact in percussing this region. The two sacs of the pleura, as they pass between the spine and sternum to form the mediastina, are interposed between the lungs and the heart. The heart is subject to slight change of position from the influence of the contiguous organs. It is carried a little downwards during violent contraction of the * In the lower animals its position is vertical, occupying the mesial line of the body. diaphragm, and is pressed upwards when the abdominal viscera are strongly compressed by the powerful contraction of the abdominal muscles. During expiration it has been seen to recede deeper into the thorax, and during inspiration again to come forward. When the body is bent to the right side, the apex recedes from the inner side of the left wall of the thorax ; when bent to the left side, it is still more closely approximated to it. Form and external surface. — Its form is that of a flattened cone, and it is neither symme- trical as regards the mesial line of the body, nor (as we shall afterwards find) is the organ itself symmetrical. It presents an anterior and a posterior surface; a right inferior or acute margin ; a left superior or obtuse margin ; a base, and an apex. Its anterior surface, which is also turned towards the left side, is convex and considerably longer than the posterior and right, which is flattened. On the anterior sur- face of the heart we find a distinct groove, running nearly in the axis of the. organ, passing from above downwards and from right to left, and containing the left coronary artery. A larger portion of the heart appears to lie to the right than to the left of this groove. There is a similar groove on the posterior surface, which is nearly vertical, shorter than the anterior, and contains a branch of the right coronary artery. These two grooves are connected with each other at or near the apex generally by a small notch, which is sometimes of sufficient depth to give the heart a bifid appearance.* These grooves mark the division of the heart into right and left sides. These terms are, how- ever, more applicable when describing the organ in the lower animals ; for in the human species the right side is also anterior and infe- rior, and the left side posterior and superior. Near the base of the heart and at the com- mencement of the longitudinal grooves, we find a circular groove deeper anteriorly than poste- riorly, which contains in its posterior part the coronary vein and branches of the coronary arteries. This circular groove points out the division between the auricular and ventricular portions of the heart. Two large arteries are placed in front of the anterior part of this groove, the one posterior to the other. That nearest to the groove is the aorta, which springs from the base of the left ventricle ; the one placed anterior is the pulmonary artery, which arises from the upper part of the right ventricle, and at its origin covers, along with that part of the ventricle to which it is attached, the com- mencement of the aorta. The ventricles form the principal part of the heart, and occupy the middle and apex, while the auricles are placed at the base. The base of the ventricles is con- nected to the base of the auricles. Two large veins, the superior and inferior vense cavae, * This notch in the human heart looks like the rudiments of the fissure which in the Dugong and Rytina separates the two ventricles from each other nearly up to the base. This bifid form of the heart, which is merely a temporary condition in the hu- man species, is permanent in the Dugong and Ry- tina. See Jig. 264, vol. i. p. 576. HEART. 579 enter the right, and the four pulmonary veins pass into the left auricle. The apex of the heart is in general formed by the left ventricle alone. The base of the ventricles is cut ob- liquely from before backwards and from above downwards, and this explains how the anterior surface of the ventricles should be longer than the posterior. I have found the difference of length between the two surfaces in a consi- derable number of uninjected hearts to vary from half an inch, or rather less, to an inch. There is little difference between the length of the two ventricles in the uninjected heart. In the injected heart the anterior wall not only becomes elongated but much more convex, while the posterior wall is simply elongated, so that the diffeience in length between the anterior and posterior surfaces becomes in- creased. This change is more marked in the right ventricle than in the left. Cruveilhier slates that he found the anterior surface of the left ventricle to exceed the posterior by nine or ten lines, and the anterior surface of the right to exceed the posterior by fifteen lines. These measurements have evidently been taken from injected hearts. On the surface of the heart, but more particularly upon the anterior surface of the right ventricle, a white spot, varying in size, is frequently observed. According to Baillie it is placed on the free or inner surface of the external serous membrane.* These spots are so common an appearance that it is some- what difficult to believe that they are morbid. It is, however, very probable that they are the result of some inflammatory action. ■Except in very emaciated subjects there is a greater or less quantity of fat occupying the auricular and ventricular grooves. This fat is generally in greater abundance in old subjects than in young, in accordance with the general law, that the adipose tissue in young persons is principally collected on the surface, and in old persons around the internal organs. When in greater quantity, it is deposited along the ramifications of the coronary vessels, and may, in cases of great obesity, almost completely envelope the surface of the heart. It is gene- rally placed in greater quantities on the right side than on the left. The human heart may be considered as con- sisting of two distinct hearts separated from each other by a fleshy septum, and which in the adult have in general no communication. The position of the fleshy septum separating the ventricles is marked by the ventricular grooves. Each heart consists of an auricle and ventricle which communicate by a large orifice. The right heart is occasionally termed the pul- monic heart, from its circulating the blood through the lungs ; and as it circulates the dark blood it was termed the Caur a sang noir by Bichat. The left is occasionally called sys- temic heart, as it circulates the blood through * In three hearts in which I carefully examined these white patches, I could distinctly trace the serous membrane over them. See the observations of M. Bizot (Memoires de la Societe Medicale d'Observation de Paris, torn. i. p. 347, 1836,) on these spots. the body generally, and is the caur d saiig rouge of Bichat. The auricles, from their immediate connexion with the large veins of the heart, sometimes receive the name of venous portion of the heart ( pars cordis venosa) ; and in the same manner the term arterial portion of the heart ( purs cordis arteriosa ) has been applied to the ventricles from dieir connexion with the large arteries. In describing the different ca- vities of the heart we shall take them in the order in which the blood passes through them. Right auricle ( auricula dextra vel inferior, atrium venarum cavarum ). External surface. — To see the external form of the auricles pro- perly it is necessary that they be first filled with injection. The right auricle is of an irre- gular figure, having some resemblance to a cube, and occupies the anterior, right, and in- ferior part of the base of the heart. It receives all the systemic venous blood of the body. Its inferior portion rests upon the diaphragm. Its largest diameter runs in a direction from behind forward, and from right to left. It is broadest posteriorly, becoming narrow and pro- longed anteriorly, where it terminates in a small and free appendix, which, from its re- semblance to the external ear of the dog, has been termed auricle. This appendix is gene- rally serrated on the edges, more particularly on the external, and projects between the aorta and the upper and anterior margin of the right ventricle. To this smaller portion the term proper auricle has been given, while the larger portion has been called sinus vcnosus. This division of the auricle into proper auricle and sinus venosus is more distinct in the left than in the right auricle. The posterior surface of the right auricle is connected with the entrance of the two cava? ; its inferior with the base of the right ventricle ; its internal with the left auricle; its outer surface is free; and anteriorly it is prolonged into the proper auricle. The junction of its internal surface with the cor- responding surface of the opposite auricle is marked by an indistinct groove, which cor- responds to the attachment of the septum sepa- rating the two auricles. Its external surface is placed on a plane internal to the outer edge of the ri;j;ht ventricle. Internal surface. — The innpr surface of the right auricle can be satisfactoiily examined only when it is opened in situ. Its interior can be best exposed by making a longitudinal incision from the appendix to the orifice of the inferior cava, then opening the superior cava along its anterior surface and connecting the two inci- sions. The inner aspect of the right auricle presents four surfaces: — 1. a posterior, where the two venje cavee enter ; 2. an outer, upon which numerous muscular bands are seen standing in relief; 3. an internal, which is nearly smooth, forms the septum between the two auricles, and presents an oval depression, about the size of the point of the finger, called the fossa ovalis ; 4. an anterior, formed by the appendix, and which also presents numerous muscular bundles. The superior or descend- ing vena cava enters at the upper and posterior angle, the inferior or ascending cava at the 2 Q 2 530 HEART. posterior and inferior. The entrance of the superior cava looks downwards and forwards in the direction of the body of the auricle; the entrance of the cava inferior is directed up- wards, backwards, and inwards. These two orifices are circular, and that of the cava infe- rior is larger than that of the cava superior. The right margins of these veins are continuous with each other ; the left or anterior margins are continuous with the auricle, which in fact appears at first sight to be formed by an ex- pansion of the veins ; hence the term sinus venosus. Around the left margin of the en- trance of the cava superior there is a prominent band of muscular fibres; and around its right and posterior margin there is another but less prominent band placed at its angle of junction with the right margin of the inferior cava. This last band occupies the position of the sup- posed tubercle of Lower ( tuberculum Loweri ). The cava inferior occasionally forms a dilata- tion immediately before it enters into the au- ricle. The venae eavae have properly no valves at their entrance into the auricles.* The fossa ovalis (valvula foraminis ovalis, vestigium fo- raminis ovalis ), which marks the position of the foramen ovale by which the two auricles communicated freely with each other in the foetus, is seen at the lower and right portion of the auricle, partly placed in a notch in the posterior and lower part of the fleshy portion of the septum, and partly in the upper part of the vena cava ascendens as it passes in to form the sinus venosus. The upper and anterior margins of this depression are thick and pro- jecting (annulus seu isthmus Vieusseni, columna foraminis ovalis ). This was supposed by Vi- eussens to prevent the blood of the cava supe- rior from falling into the cava inferior, an effect which Lower also imagined might be produced by the tubercle which he supposed was placed at the junction of the two veins. We have already pointed out that the orifices of the two veins are placed in different directions, which is sufficient to prevent the descending column of blood falling directly upon the ascending. The posterior and lower margins of the fossa ovalis are ill-defined. The surface of the de- pression is sometimes smooth, at other times uneven and reticulated. Between the upper margin of the depression and the annulus or thickened edge of the fossa ovalis we frequently find a small slit passing from below upwards, and forming a valvular opening between the two auricles. The remains of the Eustachian valve (foraminis ovalis anterior valvula) may be seen running from the anterior and left side of the entrance of the cava inferior to the left side of the fossa ovalis, where it attaches itself to the annulus. This valve exhibits very va- rious appearances in the adult: sometimes it is very indistinctly marked, at other times it is sufficiently apparent, and much more rarely it approaches the size which it presents in foetal life. It is frequently reticulated. Its convex * The Eustachian valve cannot be considered as essentially connected with the cava inferior in the adult. margin is attached to the surface of the vein and auricle ; its concave margin is free ; its su- perior and convex surface looks towards the auricle, and its lower and concave surface to- wards the entrance of the vein. Placed to the left of the Eustachian valve, and between it and the upper and outer part of the base of the ventricle, is the orifice of the coronary vein. A valve ( valvula Thcbesii ), the free and concave margin of which is directed upwards, covers the entrance of this vein. It is sometimes im- perfect, occasionally reticulated. Instead of one coronary valve we may have two or more, one placed behind another. These two valves, viz. the Eustachian and Thebesian, are formed by a reduplicature of the lining serous mem- brane of the heart. The Eustachian valve frequently, however, contains some muscular fibres at its fixed mar- gin. A number of small openings (foramina Thebesii) may be seen on the inner surface of the auricle, some of which lead into depres- sions ; others are the orifices of small veins. The muscular fibres projecting from the ante- rior and outer surface, already alluded to, pass vertically from the auricle to the edges of the auriculo-ventricular opening. These, from their supposed resemblance to the teeth of a comb, are termed musculi pectinati. Smaller bun- dles cross among the larger, giving the inner surface at this part a reticulated appearance. At the places where the transverse fibres are deficient, the outer and inner serous mem- branes of the heart lie in close contact. In the floor or base of the auricle there is a large oval opening leading into the ventricle (right au- riculo-ventricular opening), having its upper margin surrounded by a white ring. The up- per part of this ring has a yellowish colour from the auricular tendinous ring being here translucent, so that the fat lying in the auri- cular groove is seen through it. Right ventricle ( ventriculus anterior, v. dex- ter, v. pulmonalis.) External surf ace. — The right ventricle occupies the anterior and inferior por- tion of the right side of the heart. Its form is pyramidal, the base looking towards the au- ricle, its apex towards the apex of the heart. Its walls are much thicker than those of the auricle. This thickness arises from the in- creased number of its muscular fibres. Internal surface. — The right ventricle may be best opened by making an incision along its right edge from the base to the apex, and another from the root of the pulmonary artery along its anterior surface near the septum to join the other at the apex. On examining the interior, its internal and posterior walls are seen to be common to it and the opposite ventricle, the anterior and external walls to belong exclusively to itself. Its posterior and internal walls are convex, its anterior and internal concave. Its posterior and external walls are decidedly shorter than its internal and anterior. Its parietes are rather thinner at their attachment to the anterior margin of the septum than along its posterior margin. They are also considerably thinner at the apex than towards the 'base. A number of fleshy columns HEART. 58 \ ( columns cameo,, teretes lacerti) project from the inner surface. We will find that they present three different appearances in both ventricles. 1. The more numerous are attached to the .walls of the ventricles by their two extremities, so that we can introduce a probe under the middle part. These divide and sub- divide in a variety of ways. 2. Others are attached to the walls of the ventricles by the whole of their external surface, while their internal surface stands in relief from these walls. 3. Others are fixed to the walls of the ventricle by their lower extremities, are perfectly free in the rest of their course, and terminate either in a blunt extremity or in several short pro- cesses. These last are few in number, nearly vertical, and have received the name of musculi papillures. These columnae carnese form an in- tricate network on the inner surface of the ventricle, and some of them occasionally cross its cavity near the apex. They are more numerous on the anterior and external than on the posterior and internal walls. Two large openings are placed at the base of the ventricle. The larger, oval in the empty, somewhat cir- cular in the distended heart, is the right auriculo-ventricular opening, the upper margin of which was already seen in the right auricle. The smaller is circular, is placed anterior and to the left, is about three-quarters of an inch higher than the larger, and is the orifice of the pulmonary artery. That portion of the ven- tricle from which the pulmonary artery springs is prolonged upwards above the level of the rest of the ventricle. To this prolongation Cruveilhier has given the name of the infun- dibulum.* The inner surface, particularly the posterior part of this infundibulum, is smooth and deprived of columnae carnea-. Around the auriculo-ventricular opening a valve is placed, the fixed margin of which is attached to the circumference of the opening; the free margin projects into the ventricle. This valve, which forms a complete ring at its attachment, termi- nates in several apices, three of which are much more prominent than the rest, and on this account it receives the name of the tricuspid or triglochin valve (vulvulu trigloclris v. tri- cuspis). The anterior of these three portions, which is placed on the side nearest to the orifice of the pulmonary artery, is more prominent and broader than the posterior and internal portions, and is separated from them by deeper notches than these two are from each other. From this circumstance some are inclined to consider this valve as consisting of two portions only. It contains several small tubercles at its free margin. * This part is very minutely described by Wolff under the term conns arteriosus. Under the term infundibulum Wolff included a larger portion oi the ventricle, apparently that portion placed above a line drawn from the upper and right margin of the ventricle obliquely downwards to the anterior fissure. As the upper part of the right ventricle becomes gradually narrower, he supposed that it increases the velocity and impetus of the blood as it is driven from the ventricle. — Acta Acad. Imper. Petropol. pro anno 1780, torn. vi. p. 209. 1784. This valve, like the other valves at the arterial and left auricular orifices, to be afterwards described, is composed of a reduplicatureof the lining membrane containing some tendinous fibres between them. It is translucent and of great toughness. A number of tendinous cords ( chorda tendinete ) pass between the apices of these valves and the inner surface of the ven- tricle. Though the arrangement of these chordae tendineae is not uniform in all cases, yet it is of importance to remark, as prominently bearing upon the discussions connected with the man- ner in which these valves at the auriculo-ven- tricular opening perform their office, that their general distribution is the same, and evidently intended for a specific purpose.* The greater part of these chordae tendineae spring from the free and blunt extremities of the third kind of columnae carneae (musculi papillures ) which we have described ; some from the other two kinds, and others again from the smooth portion of the septum, and more particularly from the low;er part of the smooth surface which leads into the infundibulum. These tendinous cords diverge to reach their insertion, some of them dividing and subdividing two or three times, occasionally crossing each other, and are inserted principally into the apices and margins of the notches which separate the valve into its three portions. A few of these cords pass between the columns and inner surface of the ventricle without being attached to the valve. The internal lip of the valve has its lower margin tied more closely down to the surface of the ventricle by these cords than the other two lips ; besides several short cords frequently pass between the internal surface of the ven- tricle and the ventricular surface of that portion of the valve. At the exit of the pulmonary artery from the upper, anterior, and left part of the ventricle, three valves are placed ( fig. 268). These from their form have received the name of semilunar or sigmoid valves. Their fixed margins are convex, and adhere to the tendinous ring to which the origin of the artery is attached ; their free edges, from the presence of a small triangular tubercle in the middle of each ( cor- pus Arantii, corpusculum Morgagni, corpus sesamoideum,) form two slight semilunar curves (fig. 268). Theextremitiesof the curved attached edges look in the course of the artery. When the blood rushes from the ventricle into the pulmonary artery, the valves are laid against the sides of the vessel, and the free edge becomes vertical ; when, on the other hand, a portion of the blood falls back towards the ventricle, the valves are thrown inwards and completely occupy the calibre of the artery. At this time the concave surfaces of the valves are directed in the course of the artery, the convex surfaces towards the ventricle. These valves may be distinguished by the terms anterior, posterior or left, and superior or right. The suggestion of * Mr. T. W. King states (Guy's Hospital Reports, no. iv. p. 123.) that there is a disposition in the chordae tendineae from each fleshy column to attach themselves to the adjoining edges of two lips of the valve, as in the left ventricle. 582 HEART. Fantonus, tl>at as three circular valves meeting in the axis of a canal would leave a small space in the axis itself, so the use of these corpora Arantii may be to fill up the interval which would thus otherwise be left, has generally been adopted.* These valves are thin and transparent, yet of considerable strength. Their attached are thicker than their free margins. That portion of the pulmonary artery which is placed immediately above the attachment of the semilunar valves bulges out and forms three projections, named from their discoverer sinuses of Valsalva. These sinuses are more apparent in old than in young persons. Lef t auricle ( auricula sinistra ; a. pos- terior ; atrium seu sinus venarum pulmonalium, a. aortkum). External surface. — It occupies the upper, posterior, and left part of the base of the heart, and receives the blood brought back from the lungs by the pulmonary veins. The only part of the left auricle that can be fairly seen after the pericardium has been opened, and none of the parts disturbed, is the appendix. To see it properly the pulmonary artery and aorta must be cut through and thrown forwards. It is of a very irregular shape, some anatomists comparing it to an oblong quadrilateral, others to an irregular cuboidal figure. Posteriorly it rests upon the spinal column, from which itis separated by the parts mentioned in describing the position of the heart itself, and appears as if confined between the spine and base of the heart, — a fact which has been considerably insisted upon in some of the explanations of the tilting motion of the heart. Superiorly and to the right it is connected to the auricle of the opposite side. More anteriorly and still to the right it is free, and is separated from the right auricle by the aorta and pulmonary artery. lis base is connected to the base of the corres- ponding ventricle. The auricle is prolonged forwards at first to the left, but bends towards the right before terminating. This prolongation is the appendix or proper auricle. This appendix is longer, narrower, more curved, more denticulated on the edges, and more capacious than the corresponding part of the right auricle, and projects along the left side of the pulmonary artery, a little beyond and below the anterior margin of the left ventricle. The two left pulmonary veins enter the posterior and left side, and the two right pulmonary veins enter the posterior and right side of the auricle. The left auricle, like the right, has been divided into sinus venosus and proper auricle. Inner surface. — The inner surface may be divided into, 1st, a posterior, which is smooth, and which belongs exclusively to itself; 2d, an * I find that the late Dr. A. Duncan, jun. has justly remarked that there is no necessity for calling in the aid of the corpora Arantii to produce the complete obstruction of the calibre of the artery, as the free edges of these valves, when they are thrown inwards, do not exactly lie in close apposition but overlap each other. Besides these bodies are occasionally very indistinct, and frequently do not project beyond the free margin of the valves, especially in the pulmonary semilunar valves. anterior, which communicates by a round opening with the cavity of the appendix; 3d, a right, the anterior and greater part of which is formed by the septum of the auricles. Upon this is observed the fossa ovalis, but without the distinct depression which it presented in the right auricle. The upper margin of the valve, between which and the upper thick edge of the fossa ovalis the oblique aperture exists, which we formerly stated to be frequently observed here, is often distinctly seen in the left auricle. The valvular nature of this small slit must prevent any intermixture of the blood of the two sides. This margin, when present, looks forwards and to the left. The two right pulmonary veins open upon this surface imme- diately posterior to the septum, and between the septum and posterior surface. 4th, A left, into which the two pulmonary veins of the left side open. The pulmonary veins of the two lungs are thus separated from each other by the whole breadth of the auricle. The veins of the same side open into the auricle, the one immediately below the other, so that they occupy the whole height of the auricle. The superior is generally the larger. The two veins of the same side occasionally enter by a common opening, or this may occur on one side only. At other times we may have five openings. These veins, like the cava;, have no valves at their termina- tion in the auricle. At the lower and anterior part of the auricle a large oval opening presents itself. This is the left auriculo-ventricular opening, and like that on the right side it has its upper margin surrounded by a white tendi- nous ring. This ring, unlike that of the right side, is everywhere sufficiently opaque to pre- vent the fat placed in the auricular groove to be seen through it. The inner surface of the left auricle differs materially from that of the right in its greater smoothness, and the consequently smaller num- ber of its musculi pectinati. In fact, the only place in which these are observed, and that too to a comparatively smaller extent than in the corresponding portion of the right, is the ap- pendix. This arises from the greater strength of the left auricle, the muscular fibres being so closely laid together as not to leave any interval between them. LeJ't ventricle (ventriculus sinister, v. pos- terior, v. aorticus.) External surface. — It is of a conical shape, and occupies the posterior and left part of the heart. It is rounded and does not present the flattened appearance of the right ventricle. It projects downwards beyond the right, and forms the apex of the heart. Though the left proceeds lower down than the right ventricle, that portion of the right called infundibulum or conus arteriosus mounts higher than any part of the left. The left is on the whole a little longer than the right. The circumference of the base of the right ventricle is greater than that of the left, exceeding it in some cases in the injected heart by about two inches. Internal surface. — This ventricle is best opened by making an incision close upon the HEART. 388 anterior fissure from the apex near to the com- mencement of the aorta, then another in- cision midway between the posterior fissure and left edge of the ventricle, commencing near the base and carrying it downwards to join the other at the apex. The anterior and right parietes of the internal surface are formed by the septum ; the posterior and left belong ex- clusively to itself. The walls of the left ven- tricle are considerably thicker than those of the right, and remain apart, while those of the right fall together. As connected with this we may observe that the septum is concave towards the left ventricle and convex towards the right. As the obstacles to be overcome in transmitting the blood through the body are greater than those to be overcome in transmitting it through the lungs, so is the left ventricle thicker than the right. It is important to remark, as connected with the pathology of spontaneous rupture of the heart, that the walls of the left, like those of the right ventricle, are considerably thinner at the apex than towards the base.* The ante- rior and right parietes are longer than the pos- terior and left. The columns may be arranged into three kinds, such as we have described in the right ventricle. They are not so numerous in the left ventricle as in the right. The greater number are also smaller, and are principally placed upon the posterior and left wall, near the apex of which they form deep areolae.f The upper part of the septum which leads to the aortic opening, which we shall presently describe, is quite smooth. In the base of the ventricle we find two openings placed closely together ; one of these, the smaller, is placed to the right and a little anterior, is the commencement of the aorta, and occupies the upper and right corner of the ventricle ; the other is larger and placed to the left and a little posterior, and is the auriculo-ventricular opening of this side. The aortic opening is only separated from the auriculo-ventricular opening by the tendinous ring, and from the orifice of the pulmonary artery by the upper part of the septum. A valve resembling the tricuspid is attached to the tendinous ring around the auriculo-ventri- cular opening, which, from being more de- cidedly divided into two lips, is termed bicuspid, and from its fanciful resemblance to a bishop's mitre has generally received the name of mitral valve. Like the tricuspid it forms a complete ring around the margin of the auriculo-ventri- cular opening. The anterior lip of the valve in the quiescent state of the heart hangs suspended between the auriculo-ventricular opening and the origin of the aorta, and is considerably larger and more moveable than the posterior, which is smaller and more limited in its move- * The circular arrangement of the muscular fibres around the apex (Jig. 274 J must have the effect ot rapidly approximating the inner surfaces of the ventricles at the apex during their systole, more particularly when the apex is elongated, as in the heart of the horse, and thus prevent the pres- sure from falling upon the extremity of the apex, where it is very weakly protected. t Laennec. has erroneously stated in general terms that the columnar of the right ventricle are larger than those of I he left. merits. The mitral valve is formed in the same manner as the tricuspid, and is somewhat thicker and stronger, and like it contains a number of tubercles in its free margin. The large anterior lip of the mitral valve projecting downwards into the ventricle was described by Lieutaud and by others since his time as dividing the ventricle into two portions, an aortic and a ventricular. These are separated from each other at the upper part by the valve only; at every other part they communicate with each other. The same authors have described the larger lip of the tricuspid valve as effecting a similar division of the pulmonic ventricle. Two of the columnar carnea; in the left ventricle belong to the third kind (musculi papillares) already described, and are much stronger than any to be found in the right ven- tricle. They are attached to the lower part of its cavity, pass upwards, and about the middle of the ventricle terminate in a blunt extremity, from which a number of chorda; tendines pass to be attached to the margins of the mitral valve. Bouillaud describes these two columns as uniformly occupying the same position, one being placed at the junction of its left and posterior walls to form the left margin of the heart ; the other on the posterior wall near its junction with the posterior margin of the sep- tum.* Each of these fleshy columns consists of two fasciculi, of an anterior and superior, and of a posterior and inferior. The posterior and inferior fasciculus is shorter and less strong than the anterior. The chordae tendineae of the two anterior or internal fasciculi proceed to attach themselves to the margins of the anterior or larger lip of the valves, those from one fasciculus passing to one edge of the lip, and those of the other fasciculus to the other edge. As these chorda; tendinea; proceed from the fasciculi to the valve, they diverge from those of the same fasciculus, but converge towards those of the other fasciculus. ( Fig. 2G9 shews the attachment of the chorda; tendineue of the two anterior or internal fasciculi.) The chorda; tendineae from the posterior fasciculi pass in a similar manner to be attached to the posterior lip. The posterior lip is fixed closer in its situation than the anterior, by the chorda; ten- dinea?, and this is frequently increased by some of these cords passing from the walls of the ventricle to be attached to the ventricular sur- face of the valve, sometimes nearly as high as the fixed margin of the valve. These chordae tendineae are stronger, fewer in number, and less subdivided than those in the right ventricle. Several of them pass between the fleshy columns without being attached to the valves, as in the right ventricle. Though the description here given is not perfectly uniform in every case, but is liable to frequent varieties, — by the non-divi- * I have satisfied myself by numerous examina- tions, of the accuracy of Bouillaud's account of the position of these musculi papillares and the arraa^e. rnent of the chorda; tendineae in the human heart. I have found them occupying a similar position in the heart of the horse, ox, ass, sheep, pig, do"-, rabbit, hedge-hog, and some birds, and suspeet that this will be found a general law in all th 1& 1 9 ■IS » 81 ST v> 1TB line. n me. 31 " 2* 25 57 1 m 30 to 49 years . . 50 to 79 years . . Average from 16 ) to 79 years Right ventricle, female. 1 to 4 years .... lfB line. I line. Jj| line. 30 to 49 years , 50 to 79 years . \\ Average from 15 } j2 to 59 years . . S 3 Care was taken to make all these measure- ments at points where there were no columnar carneae. The thickness of the septum ventriculorum, according to Meckel, is 11 lines at its base. Bouillaud obtained the same results in the only case in which he appears to have measured the thickness of the septum. M. Bizot has given measurements of the ventricular septum at six different periods of life, from which I have selected the following. Male. Female. Age. Middle part. Middle part. 1 to 4 years 3T'5 lines. 2f lines. 16 to 29 years.... 4\} „ 4f} „ 50 to 79 years 5J „ 5$ „ The thickness of the septum ventriculorum goes on increasing in thickness from infancy to an advanced period of life. Relative capacities of the several cavities. — The most conflicting statements exist upon this point, and we find it perfectly impossible to come to any satisfactory decision. Each cavity of the heart is supposed, when mo- derately distended, to contain rather more than two ounces of fluid. The auricles may be safely said to be of less capacity than the ventricles ; and this disparity is strikingly marked in the larger animals, as the horse and ox. The right auricle is generally allowed to be larger than the left, and the difference, 586 HEART. as stated by Cloquet and Cruveilhier, is as 5 to 4. The right ventricle is generally found larger than the left after death. This difference has been very variously estimated by different anatomists. Some, as Winslow, Senac, Haller, Lieutaudj* and Boyer, have maintained that there is a marked disparity between the capa- cities of the two cavities, while Meckel, Laennec, Bouillaud, Portal, and others be- lieved that this difference is to a smaller extent. Lower was the first to maintain that both ventricles are of equal size. Sabatier, Andral, and others have supported this opinion ; while Cruveilhierf states that he has satisfied himself, from comparative injections of the two cavities, that the left ventricle is a little larger than the right. Gordon has occasionally found both ventricles of equal size, and Portal has seen them of the same size in young persons. Santoriniand Michelattus believed that, though the capacity of the left ventricle appears a little smaller than that of the right, yet that the superior force of the left auricle over the right dilates the left ventricle sufficiently to render it equal to the right. The majority of anatomists, however, have always maintained that the capacity of the right ventricle is greater than that of the left, and have adduced the following arguments in support of this opinion: 1, that the right auricle, right auriculo-ventricular orifice, and origin of the pulmonary artery are larger than the auricle and corresponding orifices of the opposite side : 2, that when both ventricles have been filled with water, mercury, or wax, more of these substances is found contained within the right than the left : 3, the experi- ment of LegalloisJ shew that when an animal is bled to death, this disparity between the size of the ventricles is still found. Those who maintain that the capacity of these two cavities is equal do so on the following grounds: — 1, that as the walls of the right ventricle are weaker than those of the left, when the same force is used in injecting both, the right must, as a matter of course, be more dilated than the left. 2. Sabatier ingeniously suggested that, as during the last moments of life the passage of the blood from the right side of the heart is generally impeded, producing engorgement of that side, while the left side was generally empty, this might account for the greater size of the right ventricle. 3. Sabatier and Weiss§ maintained that in those cases where the kind of death was such that the right side of the heart could not be en- gorged as in fatal haemorrhage, no difference between the capacity of the two sides could * Memoires de l'Academie Roy. des Sciences, t. viii. p. 561, 1754. Lieutaud's authority is some- times quoted in support of the opinion that these cavities are of equal capacity. t Anatomie Descriptive, t. iii. | Dictionnaire des Sciences Med. t. v. p. 436. These experiments were performed upon dogs, cats, guinea-pigs, and rabbits. § De dcxtro cordis ventriculo post mortem am- plijre. be observed. 4. The experiments of Sabatier, in which, after tying the aorta and producing engorgement of the left side of the heart, while the right side was emptied by a wound . made into the vena cava or pulmonary artery, the left ventricle was found to be of greater capacity than the right. M. Bizot maintains that the capacity of the ventricles goes on increasing from youth up to old age ; and that this, contrary to the opinion of Beclard, is not so rapid in old age as in the earlier periods of life.- The following are a few of M. Bizot's measure- ments : — Left ventricle, male. Age. Length. Breadth. 1 to 4 years 20 lines. 31 lines. 50 to 79 years .... 36 „ 56| „ Average from 15 to ) „.M , . s 79 years $ 6^ " _ " Left ventricle, female. 1 to 4 years 18^ lines. 29§ lines. 50 to 79 years 31 „ 49± „ Average from 15 to ) „. , .„23 89 years S 35 " 55 " Right ventricle, male. 1 to 4 years 201 lines. 47§ lines. 50 to 79 years .... 37± „ 87 „ Average from 15 to) „7M o.,n 79 years S " m " Rig/it ventricle, female. 1 to 4 years ..... 18J lines. 44J lines. 50 to 79 years 35{J „ 76 „ Average from 15 to ) „ . 89 years S " * " Every one must confess that the right ven- tricle is generally found larger after a natural death in the human subject than the left ; and it appears exceedingly probable that these two cavities, in the healthy state of the organ, contain different quantities of blood during life. As the capacity of the auricles is rather smaller than that of the ventricles, it may be asked how can the auricles furnish blood sufficient to distend the ventricles ? We shall afterwards more particularly explain that the blood passes from the auricles into the ven- tricles at two different times during the interval between each contraction, viz. at the moment of its relaxation, and again during the con- traction of the auricles. Various attempts have been made by those who maintain that the right side of the heart is larger than the left, to explain how the equilibrium of the circulation can be maintained. Ilelvetius* supposed that this could be accounted for by the diminution which the blood suffered in passing through the lungs ; and in proof of this he erroneously maintained that the pulmonary arteries were larger than the pul- monary veins. Legallois believed that this could be explained (as appears very probable) by the greater size of the right auriculo-ven- tricular opening, allowing a greater reflux of blood back again into the auricle, during the systols of the ventricles. * Memoire de l'Acad. Roy. 1718, p. 285. HEART. 587 Relative dimensions of the auricula -ven- tricular orifices,. — The right auricula-ventricular orifice is larger than the left, as was correctly stated by Portal.* According to Cruveilhier, the largest diameter of. the right auriculo- ventricular opening which is antero-posterior is from 16 to 18 lines, and its smallest diameter is 12 lines; while the largest diameter of the left auriculo-ventricular opening, which is di- rected almost transversely, is from 13 to 14, and its smallest is from 9 to 10 lines. Bouillaud gives the results which he obtained from the accurate measurement of the circumference of these two openings in three perfectly healthy hearts. The average circumference of the left auriculo-ventricular opening was 3 inches 63 lines : the maximum was 3 inches 10 lines, and the minimum was 3 inches 3 lines. The average circumference of the right auriculo- ventricular opening was 3 inches 10 lines: the maximum was 4 inches, and the minimum was 3 inches 9 lines. Circumference of the aortic and pulmonary orifices. — The circumference of the aortic and ventriculo - pulmonary orifices is sometimes nearly equal ; more generally, however, the ventriculo-pulmonary is the larger. Bouillaud gives the following measurements of these openings taken from four healthy hearts : — Average circumference of the aortic opening, 2 inches 5J lines: the maximum 2 inches 8 lines, and the minimum 2 inches 4 lines. Average circumference of the ventriculo-pul- monary opening, 2 inches 7| lines : the maximum 2 inches 10 lines, and the minimum 2 inches 6 lines. I have found this difference between the circumference of these two open- ings marked distinctly at seven years of age. M. Bizot has given measurements of the ar- terial orifices, of which the following is the average. Aortic orifice, male. Average from 16 to 79 years. . 45^- lines. Aortic orifice, female. Average from 16 to 89 years . . 413 lines. Pulmonary orifice, male. Average from 16 to 79 years . . 54Jf lines. Pulmonary orifice, female. Average from 16 to 89 years . . 48^ lines. Size and weight. — Laennec has stated that the size of the heart in general nearly corre- sponds to the closed fist of the individual. This can only be considered as a loose ap- proximation, as the size of the hand may vary in different individuals otherways resembling each other, either from original conformation or from dissimilar modes of life ; and., besides, the size and form of the healthy heart itself may vary sufficiently to effect an apparent difference in these respects. The average length of the heart, according to Meckel, is 5J indies, of which about 4 inches are to be allowed for the ventricles, and \ \ inch for the auricles. Bouillaud found that a line drawn from the origin of the aorta to the point of the heart ranged, in nine * Anatomie Medicalc, t. iii. p. 69. healthy hearts, from 4 inches to 3 inches 2J lines. The average length was 3 inches 7J lines. The weight of the heart, according to Meckel, is about 10 ounces, and its propor- tionate weight to the whole body is as 1 to 200. Tiedemann is of opinion that the proportionate weight of the heart to the body is as 1 to 1-60.* The weight of the healthy and empty heart, according to Cruveilhier, is from 7 to 8 ounces. Bouillaud found the average weight in thirteen healthy hearts to be 8 ounces 3 drachms. According to Lobstein it weighs between 9 and 10 ounces. The size and weight of the heart must generally be to a great extent in. conformity with the size and weight of the body. In an athletic male we would expect it to weigh about 10 ounces, in an ordinary-sized individual about 8 ounces, and in weakly persons, or in cases of pro- tracted debility, it would be still more dimi- nished in weight. For the same reason it is generally larger and heavier in males than in females. Structure of the heart. — The heart consists of muscular and tendinous textures, of cellular tissue, of bloodvessels, of nerves, and of lym- phatics, enclosed between two serous mem- branes. Tendinous texture.- — The tendinous texture of the heart is placed, 1, around the auriculo- ventricular and arterial orifices; 2, within the reduplicature of the lining membrane forming the auriculo-ventricular and arterial valves ; 3, it forms the chorda? tendinea?. Auriculo-ventricular tendinous rings. — Around each auriculo-ventricular opening we find a tendinous circle or ring, from the upper part of which the muscular fibres of the au- ricles arise, and from the lower part those of the ventricles, thus affording perhaps the only example in the human body of a strictly in- voluntary muscle having tendinous attach- ments. The tendinous ring surrounding the left auriculo-ventricular opening is stronger than that surrounding the right. These tendinous zones are thicker along the lower edge where the muscular fibres of the ventricle are attached, and become thinner along the upper edge where the muscular fibres of the auricles are attached, so that the fat occupying the auricular groove is seen through the upper portion of the ring on the right side. The right margin of the left auriculo-ventricular ring is connected with that surrounding the aortic opening. The existence of the auriculo-ventricular and arterial tendi- nous rings was well known to Lower.f Arterial tendinous rings. — The form of the tendinous rings surrounding the arterial open- ings, and the manner in which the large arte- ries are attached to their upper edges, have not, I think, been described with sufficient accu- racy. These textures are very plainly observed * If wc consider the ordinary weight of an adult heart to be 8 ounces, and the average weight of the whole body to be 150 lbs. the proportionate weight of the heart to the body would be as I to 225. f Tractatus De Corde, p. 29. 1669. 588 HEART. in the heart of the ox and horse after a little dissection. The following description is drawn up from numerous dissections of these parts made on the human heart. The tendinous ring surrounding the aortic opening is stronger and thicker than that surrounding the orifice of the pulmonary artery. Both of them are stronger than the auriculo-ventricular rings. Each of the arterial rings appears as if composed of three semilunar portions placed on the same plane, the convexities of which are turned towards the ventricles and the concavities to- wards the vessels (fig. 266, a a ')* Each of Fig. 266. Appearance of tendinous ring at the origin of the pulmonary artery. In slitting open the artery, one of the three projecting extremities of tlie ten- dinous ring has been divided. these semilunar portions has its projecting extre- mities intimately blended at their terminations with the corresponding projecting extremities of those next to it, (Jig. 266, b b,) so that the three form a complete circle, with three trian- gular portions projecting from its upper edge. The semilunar portions approach fibro-carti- lage in their structure, and have the intervals left between their convex edges filled with a texture more decidedly fibrous, (fig. 266, d,) and which is considerably weaker than the se- milunar portions, more particularly on the left side of the heart. f The thinness of the ten- dinous structure filling up these intervals has led some anatomists erroneously to describe these portions of the heart as protected only by the two serous membranes. The right ten- dinous zone is broader than the left and very thin, particularly at its inner margin, at which part in both sides of the heart it assumes more of the tendinous than of the fibro-cartilaginous structure. These tendinous rings are placed obliquely from without inwards and from above downwards, so that the outer edge is on a plane superior to the inner. The sigmoid valves are attached to the inner edge of the upper surface, (fig. 267, a,) and the tendinous fibres placed in the fixed margins of these valves contribute to the thickening of the ring at this part ; the middle coat of the arteries is connected to the outer edge of the same surface, and to the an- terior part of the projecting extremities, (fig. 267, b ;) while the muscular fibres of the ven- tricles (fig. 266,/; fig. 267, f}) are attached to the lower surface of the projecting portion of the convexity, and to the lower margin of the fibrous tissue filling up the space between the convexities of the projecting ends, (fig. * These tendinous festoons are represented stronger in the woodcut than they are naturally. t These intervals are occupied by muscular librcs in the heart of the ox and horse. Fig. 267. Pulmonary artery slit open at its origin, its internal membrane stripped off, and two of tite sigmoid valves completely removed. a a a, tendinous festoons. b b, muscular fibres of the right ventricle. c c c, middle fibrous coat of the artery after the internal serous membrane has been stripped off. g, small portion of one of the semilunar valves left to show its attachment to the inner edge of the upper surface of the tendinous festoon. 267, d.) There is, however, this difference between the right and left arterial openings with respect to the attachment of the muscular fibres;— on the right side the muscular fibres arise from the projecting portion of the con- vexity of the whole three tendinous festoons, (fig. 268, c, c,) while in the left side the mus- Fig. 268. cular fibres are attached only to one and part of a second, (fig. 269, b b,) as the larger lip of the mitral valve (fig. 269, a ) is suspended Fig. 269. HEART. 589 from the posterior orleft^ and a great part of the anterior, — in fact to that part of the tendinous ring which separates the aortic from the auri- culo-ventricular opening. From the posterior part of that portion of the tendinous ring to which the mitral valve is connected, the ante- rior fibres of both auricles, near the septum, arise. As the left tendinous ring is thicker and narrower than the right, there is a larger space left between the fixed edge of the valves and the attachment of the middle coat of the arte- ries than there is on the left side. This space is of some importance, as upon it a consider- able part of the pressure of the column of blood in the large arteries must be thrown during the diastole of the ventricles. There is a good representation of these ten- dinous rings given in Tab. II. Opera Valsalvae, torn. i. At page 129 they are thus described : " In horum sinuum ambitu qua valvulae si- nubus annectuntur quidem quasi Agger videtur occurrere substantias durioris ad similitudinem cartilaginis tarsi palpebrarum." I find also that Gerdy* appears to have had an accurate notion of the form and appearance of these ten- dinous rings. He was aware of the existence of the projecting angles of the tendinous ring which pass up between the festoons of the middle coat of the arteries, and which have been overlooked m succeeding descriptions. I find also that the late Dr. A. Duncan, jun. has, in his unpublished manuscript, given a very accurate account of these structures in the heart of the ox. Tendinous structure in the auricula-ventri- cular valves. — Distinct tendinous fibres exist in the auriculo-ventricular valves enclosed be- tween the reduplication of the lining serous membrane. These are continuous with the auriculo-ventricular tendinous zones, and are most distinct and of great strength at the base. I could never observe any distinct traces of mus- cular fibres in these valves in the human heart either when fresh or after long boiling. Bouil- laud has, from the examination of one incon- clusive case, but principally from analogy with the corresponding valves of the heart of the ox, supposed that they may exist in some cases in hypertrophy of the valves. In making exami- nations of this kind we must be exceedingly careful not to mistake the tendinous fibres when tinged with blood for muscular fibres, for under these circumstances they certainly at all times assume the appearance of muscular fibres .f * Journal Complementaire, torn. x. t In the heart of the dog 1 have seen a distinct band of transverse muscular fibres in the base of the larger lip of the mitral valve, but could never satisfy myself of the existence of any longitudinal muscular fibres. In the heart of the ox and horse very distinct longitudinal muscular fibres are seen in the valves of both sides of the heart, princi- pally, if not entirely, continuous with the inner layer of the fibres of the auricles. A greater part pass over the inner surface of the tendinous rings, and are firmly attached to the tendinous structure of the valves, reaching nearly to the lower margin of the smaller segments of the valves. The effect of these fibres upon the movements of the valves would form an interesting subject of investigation. Tendinous structure in the arterial valves. — Distinct tendinous fibres also exist in the arte- rial valves, which must add considerably to their strength and prevent their more frequent rupture. Three of these tendinous bands in each valve are stronger than the others, and their position deserves attention, as they are often the seat of disease. One of these bands occupies the free margin of the valve, and passes between the projecting extremities of the tendinous festoons (fig. 270, a ). Upon the middle of this band the corpus Arantii, which is formed of a similar texture, is placed. The other band comes from a point a little above the middle of the projecting end of the tendinous festoon (fig. 270, b ), and passes up in a curved manner towards the corpus Arantii, leaving between it and the superior band a triangular space on each side, in which, if any tendinous fibres exist, they are exceed- ingly obscure. These two tendinous bands were well known to Morgagni. The third band is placed in the attached margin of the valve, and renders this part the thickest and strongest. Between the middle band and the attached margin of the valve a number of weaker bands are placed, which also pass up- wards, generally assuming a curved form. Mor- gagni termed these lower and weaker fibres jibra carnea, but they evidently belong to the same structure as the stronger bands. The arrange- ment of these tendinous fibres is best seen in the aortic valves, and the appearance exhibited in the accompanying representation, (fig. 270,) Fig. 270. which has been taken from Morgagni, is not always distinctly observed, where the valves are perfectly healthy, but become sufficiently obvious in certain cases of disease. Attachment of the middle coat of the arte- ries to the arterial tendinous rings. — The inner and outer serous membranes are continued from the heart upon the arteries ; the one becoming the inner coat of the arteries, and the other is continued for a short distance upon their ex- ternal surface. A thin layer of cellular tissue also passes from the heart along the arteries between their middle coat and their external serous membrane. These are, however, so far unimportant compared with the attachment of the middle coat of the arteries to the tendinous fes- toons which we have just described. The middle coat is so very firmly and strongly attached both to the external edges and to the anterior portion of the upper part of these projecting extremi- ties, (fig. 267, d,) that it can be detached with great difficulty. Those fibres of the middle coat attached to the projecting extremities, 590 HEART. which are apparently of the same number and thickness as in that portion of the artery im- mediately above, form a distinct curved edge (fig- 267, ej, as they pass from the extremity of one festoon to the other. As we trace the middle coat of the artery downwards into the concavities formed by each festoon, we find that below this curved edge they become stri- kingly thinner and continue to diminish in thickness and in length, (since they can only stretch between the projecting extremities,) until we arrive at the bottom of the concavity. These three thin portions of the middle coat must then be placed behind the semilunar valves, and correspond to the sinuses of Val- salva.* The thinness of the middle coat at the sinuses of Valsalva will render this portion of the artery more dilatable, and predispose it to rupture when its coats are diseased. f The tendinous zones are distensible, but to a con- siderably less extent than the middle coat of the arteries. I am not aware that this account of the manner in which the middle coat of the arteries is attached to the tendinous rings has been previously given. I suspect, however, that Dr. Duncan must have been perfectly aware of it from some parts of his manuscript. The differences between these tendinous fes- toons and the yellow elastic coat of the arteries, and the manner of their attachment, can easily be made out in the human heart ; they are, however, more apparent in the larger animals, as the horse and ox. The different characters of the two tissues are obvious at the first glance after boiling, even in the human heart. Muscular tissue.% — The greater part of the * So striking is the difference between the middle coat as it fills up the concavity of these festoons, and where it stretches between the projecting ex- tremities in the hedgehog, that at first sight it ap- pears to be deficient at that part. t According to Valsalva aneurisms are frequently found in this situation : *'sAtque hie aorta? sinus maximus ille est, in quo ssepe anenrysmata circa praecordia contingunt, ut propria obseivatione edoctus sum." Valsalva? Opera. Epist. Anat. ed. Morgagni, torn. i. p. 131. 1740. This greater tendency to aneurismatic dilatation must depend upon two circumstances. The increased calibre of the artery at this part will increase the pressure upon its walls from the well-known hydrostatic law, that " in a quantity of fluid submitted to compres- sion, the whole mass is equally affected, and simi- larly in all directions," and the diminished thick- ness of the middle coat will materially favour this distending force. % While I was engaged in examining the arrange- ment of the muscular fibres of the heart, Dr. Alison had the kindness to procure for me the manuscript of the late Dr. A. Duncan, jun. on this subject. It was well known not only in this country but on the continent that Dr. Duncan had for a very long pe- riod attended very particularly to this question, and was in the habit of demonstrating the parts he had ascertained to his pupils. Unfortunately his inten- tions of publishing on the subject were never car- ried into execution, and his papers referring to it were left in so confused a state that it is exceed- ingly difficult and in most parts impossible to make out the description. I have availed myself of those parts that are legible in the following pages, and these I have scrupulously acknowledged. Dr. Dun- can's dissections of the heart were taken entirely from the ox and sheep. heart is composed of muscular fibres arranged in a very intricate manner. These fibres are connected together by cellular tissue,* which, however, exists in much smaller quantity in the heart than in the other muscles of the body. These fibres are attached generally by both extremities to the tendinous rings situated around the orifices of the heart; the fibres of the auricles pass upwards to form the auricles, and those of the ventricles downwards to form the ventricles, so that these tendinous rings must form the fixed points towards which all the contractions of the heart take place. None of the muscular fibres of the auricles are con- tinuous at any part with those of the ventricles, and we will find that while some of them are confined to a single auricle, others belong to both. In the same manner a great part of the fibres of the ventricles are common to both, and are interwoven together, while others again belong exclusively to a single ventricle, or, as Winslowf expressed it, the heart is com- posed of two muscles enveloped in a third. The intimate arrangement of these muscular fibres, particularly those of the ventricles, is exceedingly complex, as the contraction of the organ is not in one particular direction only, but in all directions, and has long been con- sidered as a kind of Gordian knot in anatomy. Vesalius, Albinus, and Haller J confessed their inability to trace them, and more lately De Blainville§ assures us, from his own experi- ence, that we can only arrive at very general conclusions ( des chases trts-gtnerales) on this subject. By adopting the method of long- continued boiling of the organ before com- mencing to attempt to trace the course and ar- rangement of its fibres, we will find that after a few trials several of the most important points connected with the distribution of these can be ascertained, and by perseverance they can be unravelled to a great extent. By long boiling the muscular fibres are rendered hard and firm, while the tendinous and cellular tissues are softened or dissolved, and the fat melted. Dr. Duncan, who employed this method to a great extent, states that the essential circumstance is to continue the boiling long enough, and that he has never been able to carry it too far. I have found from eighteen to twenty hours gene- rally sufficient for this purpose. Some have recommended that the heart should be pre- viously put for a short time into a strong solu- tion of salt, and Vaust advises that it should be boiled in a solution of nitre, for the purpose of rendering the fibres firmer. The boiling is infinitely superior to the maceration in vinegar. By stopping the boiling before the tendinous rings are rendered too soft, we can easily see their form and their connexions to the muscular fibres. The eeneral connexion and distribution of * [This however is denied by other observers, and from very recent and careful examinations. See the succeeding article by Mr. Searle. — Ed.] t Memoires de l'Academie Royale des Sciences, 1711, p. 197. X El. Phys. torn. i. p. 351. § Cours de Physiologie, &c. torn. ii. p. 359. HEART. 591 the muscular fibres of the ventricles may be stated to be as follows. 1st, Most of these fibres are connected by both extremities to the tendinous structure of the heart, a fact well known to Lower,* though overlooked by many subsequent anatomists. 2d, The direction of these fibres is more or less oblique, a com- paratively small part of them only being vertical, and that too for a limited part of their course. The degree of obliquity of these spiral turns is different in different por- tions of the heart : they are more ob- lique on the surface and less oblique as we proceed to the deeper fibres, more particularly at the base. The deeper fibres approach more to the cir- cular form. 3d, As has been already stated, part of these fibres are common to both ventricles; while part only belong exclusively to a single ventricle, and that principally at the base. 4th, The external fibres are longer than the next in order, and after turning round the apex pass upwards into the interior, below the lower margin of the shorter fibres, and form the inner surface of the ventricles, while the deeper again turn up below the lower margin of the fibres next in succession, so that the longer enclose by their two extremities all the shorter fibres. By this arrange- ment we can explain how the base and middle part of the ventricles should be much thicker than the apex. This arrangement has been particularly in- sisted upon by Dr. Duncan and Gerdy, and to illustrate it Gerdy has given an ideal illustration, of which fig. 271 is a copy. Fie. 271. run in a spiral manner from above downwards and from right to left, while those on the pos- terior surface, which are in general more ver- tical, run from left to right. Most of these bands are thin and broad at the upper part, and become narrower and thicker as they ap- proach the apex, where they form a remarkable twisting, which has been termed the vortex, (of which jig. 272, taken from the human heart after boiling, is an accurate representation,) and then pass in to assist in forming the inner surface Fig. 272. of the left ventricle and the columnar carnere. The manner in which the external fibres turn in at the apex to form the inner surface of the ventricles and enclose the deeper fibres was well known to Lower, and he has illustrated it by an engraving, of which Jig. 273 is a copy. In examining the course of the fibres of the ventricles we shall not attempt to describe each particular band of fibres, but confine ourselves to their general arrangement.f In examining the surface of the ventricles the superficial fibres of the anterior surface are observed to * Tractatus de Corde, p. 34 to 37. Lugd. Batav. 1669. t Wolff has named and minutely described eight distinct bands of muscular fibres on the surface of the right ventricle : Acta Petropolit. pro anno 1781, torn. viii. p. 251, 1785. 592 HEART. This arrangement of the external fibres was also well known to Winslow* and Lancisi.f Winslow, however, denied that they described the figure of eight, as stated by Lower. More lately Gerdy has given a description of this arrangement, to which he has added an en- graving, which approaches more to the ap- pearance of the perfect figure of eight than that given by Lower. I, however, prefer that given by Lower, as it more nearly resembles the arrangement which I have myself seen in tracing these fibres. A small part of the right and posterior side of this vortex is formed by fibres from the posterior surface of the left ventricle, and from that part of the posterior surface of the right ventricle near the septum, and are attached above to the auricular tendi- nous rings, while the whole of the anterior and left side of the vortex is formed by fibres from the anterior surface and right margin of the ventricles. On tearing these last fibres, which form the principal part of the apex, from the anterior surface of the left ventricle, we find, as we proceed upwards, that a comparatively small part of them cross the anterior fissure upon the right ventricle to reach the right au- ricular tendinous ring. The greater number dip in at the anterior longitudinal fissure, and we shall afterwards find that they can be traced to the base of the septum of the ventricles. By tearing off' these fibres downwards, we open into the apex of the left ventricle. A general notion of the manner in which these fibres, passing from the base of the septum, turn in at the apex, and proceed upwards on the inner surface of the left ventricle, may be obtained from fig. 273. To have been quite accurate the inner fibres should have been more scat- tered, and some of them represented as termin- ating in the columnse carneoe. By unravelling the fibres which form the apex, we may open into the interior of the left ventricle without breaking a single muscular fibre. Having thus opened the apex of the heart, although the point is removed, the circular edge is left entire (fig. 274, a), and is formed of another series Fig. 274. I * Memoires de l'Acad. Roy. 1711. p. 197. t De Motu Cordis : Opera omnia, torn. iv. p. 96. 1745. of fibres, which, like those taken away, ad- vance spirally from the base to the apex, and turning over the edge (fig. 274, b) ascend in the opposite direction, continuing their course after being reflected. " Proceeding in the same manner the whole apex of the left ven- tricle may be removed, and the same principle of arrangement is found throughout the whole heart even to the base. When we get down as far as the apex of the right ventricle, although the principle remains the same, its effects are more complicated, as it applies to two cavities instead of one." I have frequently satisfied myself of the correctness of the description contained in this passage, which I have quoted from the manuscript of Dr. Duncan. This is the same kind of arrangement which, we have already stated, has been insisted upon by Gerdy, but which we believe can be more satisfactorily seen by tracing the fibres in this manner. Gerdy lays it down as a general law, that all the fibres of the heart form loops, the apices of which look towards the apex of the heart (fig. 271). I find that Dr. Duncan states that while the apices of those loops which form the lower part of the heart point to the apex, as Gerdy has described, " yet he commits a great error when he asserts that the apices of all the fibres of the heart point in that direction, since the number of tops which point in the opposte direction is not less."* When the superficial fibres of the heart have been removed as represented in fig. 274, we will find that if we trace the great mass of fibres occupying the lower and middle part of the left ventricle, they will be seen to run spirally in strong bundles from above down- wards and from right to left, to wind round and form the posterior as well as the anterior part of the point of the heart; that the greater mass pass in at the apex of the left ventricle to assist in forming the columnae carneae and in- ternal surface, while others pass in at the apex of the right ventricle, and others again, after turning a little upwards, dip into the interior below some of the higher fibres. On tracing them upwards, on the other hand, they dip in at the anterior longitudinal fissure (fig. 274, d) where they are as it were dovetailed with other fibres from the anterior surface of the right ventricle passing in at the same fissure, and then mount almost vertically upwards to the base of the septum, forming part of the sep- tum of the right ventricle, only separated from its lining membrane by a thin layer of fibres, and are inserted in a strong band in the ox into the bone of the heart, which is placed between the auriculo-ventricular openings and aorta, while in the human heart they are spread * I could not discover in Dr. Duncan's manu- script any other description or allusion to the fibres here mentioned whose arrangement is opposed to the general law which Gerdy is anxious to establish. There is no doubt, however, that many of these loops at the base are principally directed to the periphery of the organ, and very little downwards, and that a few in the infundibulum are slightly directed upwards. HEART. 593 over a wider surface at this their upper in- sertion. I have been more particular in describing this part of the heart, as this ar- rangement of the fibres appears to me to be intimately connected with the production of the tilting motion of the heart. The fibres which occupy the upper part of the anterior surface of the left ventricle, as well as those occupying the upper part of the posterior surface (nearer the base than those bands already described as passing from the ante- rior surface), partly dip into the interior of the left ventricle as they wind round it, partly pass in at the posterior longitudinal groove to assist in forming the septum, while other strong bands, more particularly near the base, cross this groove and dip into the interior of the right ventricle. In the human heart I have stripped off pretty strong superficial bundles from the upper part of the posterior surface of the left ventricle over the posterior longitudinal groove, and over the surface of the right ventricle as far as the anterior longitu- dinal fissure, into which they dipped. In stripping off the fibres from the posterior and anterior surface of the right ventricle at this stage of the dissection, part of them disap- pear in their course around the ventricle, where they dip in to assist in forming the interior; others proceed as far as the anterior groove before they dip inwards; while part of the fibres which arise from the conus arteriosus cross the upper part of the anterior fissure upon the anterior surface of the left ventricle, where they pass into the interior of the left ventricle. These fibres, crossing the anterior surface of the right ventricle, and which dip in at the anterior fissure, form the inner sur- face of the septum of the right ventricle. On tracing those fibres which dip inwards at so many different points, they are observed to rise upwards to the tendinous rings either directly or indirectly through the medium of the chorda tendinese. In following the fibres in this man- ner we perceive the intimate connexion that exists between the two ventricles, and that their contraction must be simultaneous. We also see that comparatively few fibres cross the anterior longitudinal groove except near the base, while large bundles of fibres cross the posterior groove. When these fibres crossing the two grooves have been torn away, the two ventricles become detached from each other. By this time the apices of both ventricles have been opened. On examining the deeper fibres (which oc- cupy that part of the heart near the base), they are seen to form a series of curved bands, of one of which fig. 275 is a representation. These bands are imbricated, the lower disap- pearing by its internal extremity below the higher, so as to be inserted by that extremity into the tendinous rings at a point more in- ternal than the corresponding extremity of the higher bands. Some of these bands are com- mon to both ventricles, others belong exclu- sively to one. The fibres of the right ventricle become very complicated where they form the eonus arteriosus and fleshy pons between the VOL. II. Fig. 275. pulmonary artery and right auriculo-ventricular orifice. The fibres of the left ventricle are stronger and coarser than those of the right ventricle, while those of the conus arteriosus are still firmer than those on the lower part of the right ventricle.* " There do not occur in any part of the heart cellular sheaths or ten- dinous aponeuroses dividing bundles of fibres as separate muscular fasciculi. Although a complex it is not a compound muscle, and does not consist of a number of distinct bellies or heads. The only thing approaching to this structure are the column-ae and a strong mus- cular stay between the peripheral and septal wall of the pulmonic ventricle, and the re- ticulated texture on the inside of the ventricles, much more conspicuous in man than in oxen." " Many fibres are attached to each other by agglutination or in a manner not easily under- stood." " Many fibres bifurcate, and the di- vided fibres follow different directions : or two fibres from different parts approximate, and at last are united and proceed as one fibre. I am doubtful if this can be considered as a tendinous point of union of all three. These points of union are often arranged in one line so as to give some appearance of a pennated muscle, but the tendinous points, if they exist, do not adhere to form membranes or strings. This bifurcation is very evident in the connection of the septal with the peripheral walls of the heart. "f The auricles are formed by two sets of fibres, a superficial and a deep. The arrangement of these two sets of fibres does not follow the same laws as those of the ventricles. The su- perficial layer (fig. 276, a a, fig. 277, a a), surrounds the base of the auricles, and is of unequal height and thickness. It is broader on the anterior and narrow on the posterior surface, more particularly on the posterior and outer part of the right. It extends upwards towards their superior edge on the anterior surface, and on the posterior surface of the left as far as the inferior pulmonary veins. It is very thin, particularly on the outer and posterior part of the right auricle. In its course round the auricles the fibres diverge to enclose the appendices, and the orifices of the * Dr. Duncan has given a very minute descrip- tion of the fibres of this and other parts of the heart, which are ranch too long for insertion here. He lias also given a very accurate and minute de- scription of the bone in the heart of the ox. t Dr. Duncan. 2 n. 594 HEART. Fig. 276. large veins. These fibres cross transversely between the anterior surface of the two auricles and connect them together. These superficial fibres are also prolonged into the interauricular septum (Jig. 277, f) to assist in forming the Fig. 277. circular band of fibres which surrounds the fossa ovalis. Gerdy figures a superficial band of fibres (Jig. 276, b) as belonging exclusively to the left auricle. The deep fibres belong exclusively to a sin- gle auricle. They are superficial at various parts, where the external or circular fibres are deficient. By their inner surface they are con- nected to the inner membrane of the auricles,and a thin layer of cellular tissue unites their outer surface to the inner surface of the superficial fibres. In the left auricle Gerdy describes, 1st, a left auricular loop (Jig. 276, c c, Jig. 277, c c), which embraces the auricle from its su- perior edge to its base, which runs a little obliquely to the left, before, above, and then behind the auricle, and is attached by its ex- tremities to the auricular tendinous ring near the septum. It is contracted at that part where it passes between the pulmonary veins. 2d. The pulmonary veins are surrounded by circu- lar fibres (fig. 276, d d, fig. 277, d d), which are continued along their course to a variable extent,- — sometimes they merely surround the termination of one or more of these veins, at other times I have seen them prolonged out- wards as far as the roots of the lungs. These fibres generally form a continuous layer, and of sufficient thickness to render them capable of constricting these vessels considerably. 3d. Some fibres proper to the appendix (fig. 276, m m), which, by passing between and uniting themselves to the other fibres of the appendix, form that reticulated appearance which it pre- sents in its inner surface. Some of these fibres are circular, others form incomplete circles. In the right auricle, Gerdy has described, 1st, a right auricular loop (fig. 276, h h, fig. 277, h), which is attached anteriorly to the tendinous structure at the base of the auricle; it extends upwards in the anterior edge of the septum auiiculorum ; it then curves round the fossa ovalis, of which it forms the projecting edge, and at the orifice of the vena cava supe- rior it divides into a right and left band. The first proceeds downwards, becomes engaged with some of the superficial fibres around the cava superior, and forms the angle between them (tuberculum Loweri), from which it passes downward to the auricular tendinous ring along the right side of the cava inferior. The left division passes along the left side of the cava inferior, in the posterior edge of the auricular septum, where it intermixes with the fibres which embrace the entrance of the coro- nary vein. 2d, Some muscular fibres (fig. 276, p), which pass between the anterior part of the tendinous ring and the appendix. 3d, Some circular fibres, which surround the en- trance of the cava superior (fig. 276, o) : these do not extend upwards beyond the orifice of the vein. 4th, The bundles of fibres which arise from the right side of the auricular ring proceed upwards to the posterior part of the appendix, and form the musculi pectinati seen in the interior of the auricle. 5th, A few fibres proper to the auricle (fig. 276, w), which assume the circular form. The action of all these fibres superficial as well as deep must be to diminish the capacity of their cavities, and draw them towards the auriculo-ventricular openings, and thus favour the passage of their contents through these openings. Inner membrane of the heart. — Each side of the heart has its own lining membrane, and botli of these are closely allied to the serous membranes in structure and appearance. They are continuous with the inner coat of the vessels which open into their different cavities. These have been termed the endocarde by Bouillaud to distinguish them from the serous coat of the pericardium on the outer surface of the heart. If we commence to trace the inner membrane of the right side from the entrance of the two cava?, we find that it is folded upon itself to form the Eustachian valve at the entrance of the inferior cava ; it then passes upon the inner surface of the auricle, and at the opening of the coronary vein it is again folded upon itself to form the valve of the coronary vein. It passes through the auriculo-ventricular opening, ad- heres to the inner surface of the tendinous ring, and is there folded upon itself to assist in form- ing the tricuspid valve. It now proceeds upon the inner surface of the ventricle, and at the origin of the pulmonary artery it assists in forming the semilunar valves, and becomes con- HEART. 595 tinuous with its inner coat. If we trace they inner membrane of the left side of the heart from the entrance of the pulmonary veins, we find that, after lining the auricle, it is continued through the auriculo-ventricular opening, and is there folded upon itself to assist in forming the mitral valve. In the left ventricle it sur- rounds the chordae tendineae and unattached columnar carnese in the same manner as in the right ventricle ; and at the origin of the aorta it assists in forming the semilunar valve, and be- comes continuous with the inner coat of the artery. These membranes adhere intimately to the inner surface of the heart by close cellular tissue, and have their inner surface perfectly polished and smooth. That of the left auricle is thicker than that of the right. They are thicker in the auricles than in the ventricles. In the ventricles, except near the origin of the large arteries, they are exceedingly thin. Nerves of the heart. — The heart is supplied with nerves from the sympathetic and par vagum. The sympathetic branches come from the superior, middle, and inferior cervical gan- glia, and frequently also from the first dorsal ganglion. The branches from the par vagum come directly from the trunk of the nerve, and indirectly from the recurrent or inferior laryn- geal. The course of these on the right side differs from those of the left in some respects, and requires a separate description. These nerves, like most of the other branches of the sympathetic, are very irregular in their size, number, and origin, so that it would be difficult to find two subjects in which they are exactly alike ; they are also very irregular in their course before they reach the cardiac plexus, but become more regular when they gain the arteries of the heart, whose branches they ac- company. These nerves, after forming diffe- rent anastomoses and plexuses with each other of the same side, converge at the upper and back part of the arch of the aorta, where they form a free anastomosis with those of the oppo- site side, and then pass on to the heart. The left cardiac nerves are sometimes much smaller than those on the right side, so as to appear, as in the dissection described by Lobstein,* merely accessory to those on the right. On the other hand the size of those on the left side may pre- ponderate considerably over those on the right. The proportional size of the different nerves of the same side is also very various. When the nerves of one side are small, the deficiency is made up by the greater size of those of the op- posite side ; and when any particular branch is either unusually small or entirely wanting, its place is supplied by the greater size of the other nerves of the same side, or of those of the opposite side. The branches from the par vagum, particularly those coming from the re- current, vary also considerably in size. All the sympathetic branches of the cardiac plex- uses are of a gray colour, and are generally not so soft as Scarpa has described them. The right cardiac branches of the sympathe- * De Nervi Sympathetici humani fabrica, &c. pp. 16 & 18. tic are generally three in number: 1st, superior cardiac ( supremus et superficialis cordis) arises from the lower and inner part of the superior cervical ganglion, or from the continuation of the sympathetic between the superior and middle ganglia, or from both these origins. It generally also receives a filament from the par vagum. In its course down the neck it lies behind the sheath of the carotid artery. It anastomoses with the external laryngeal nerve and descendens noni, and sends a twig along the inferior thyroid artery to the thyroid body ; and at the lower part of the neck it sometimes divides into two branches as figured by Scarpa,* one of which unites itself to the middle car- diac, the other forms an anastomosis with the recurrent nerve of the same side. At other times it passes into the thorax either in front or behind the subclavian artery, takes the course of the arteria innominata, and reaches the pos- terior part of the arch of the aorta, where it anastomoses with branches of the middle and inferior cardiac nerves, or with branches of the recurrent. It more rarely appears to pass to the cardiac plexus without any anastomosis with the middle and inferior cardiac branches. It frequently presents a ganglion in its course down the neck. Middle cardiac nerve. — This nerve arises by several short twigs from the middle cervical ganglion. This is generally the largest of the cardiac nerves, and is named by Scarpa the great or deep cardiac nerve ( n. cardiacus me- dius, s. profundus, s. magnus). It proceeds downwards and inwards, crosses the subclavian artery, sometimes in front, at other times it di- vides into several branches, which surround the artery and again unite. It anastomoses with the branches of the recurrent, in the neigh- bourhood of which it runs, also with the par vagum, superior and inferior cardiac nerves ; and following the course of the arteria innomi- nata it passes behind the arch of the aorta to terminate in the cardiac plexus. Inferior cardiac nerve (n. cardiacns minor of Scarpa). — This nerve generally arises by fila- ments from the inferior cervical ganglion, some- times from the first dorsal ganglion, at other times from both. It proceeds behind the sub- clavian artery near to the recurrent nerve. It follows the course of the innominata close to the middle cardiac, with which it anastomoses, and proceeds to join the cardiac plexus. Left cardiac nerves. — Perhaps the differences in the course of the right and left cardiac nerves are principally to be attributed to the known differences between the large arteries of the two sides. The left superficialis cordis is figured by Scarpaf as dividing a little above the arch of the aorta into four branches ; two of these pass in front of the aorta to form an anastomo- sis with a branch of the par vagum and deep cardiac ; a third also passes in front of the aorta, to unite itself with the middle cardiac; and the remainder of the nerve proceeds behind the arch to unite itself with the cardiac plexus. * Tab. iii. Tabulae Neurologies, &c. i Tab. iv. op. cit. 2 u 2 596 HEART. The left middle cardiac nerve is generally smaller than the right, and is frequently partly formed by a branch from the inferior cervical ganglion. It passes behind the arch of the aorta, sometimes in the form of a single trunk, sometimes double, at other times triple, and generally throws itself into the upper and left part of the cardiac plexus. Cardiac plexus (great cardiac plexus of Haller) is placed behind the arch of the aorta and in front of the lower part of the trachea, extending from the arteria innominata to the right branch of the pulmonary artery, and is formed by the convergence of nearly the whole of the cardiac nerves of both sides, but more particularly of the middle cardiac nerves. There is occasionally a distinct ganglion at the junction of these nerves; more generally there is only a plexiform arrangement. From this plexus a very few branches pass upon the ante- rior surface of the aorta ( cardiuci superficiales aorta ), and anastomose with the right coronary plexus : some twigs also pass backwards to anastomose with the bronchial plexuses. By far the greater part of the cardiac plexus pro- ceeds to the heart in the form of two large divisions to form the right and left coronary plexuses which accompany the coronary arte- ries. Where the right branch leaves the lower part of the plexus there is a gangliform swelling (ganglion of Wrisberg), which is occasionally, however, very indistinct. This ganglion fur- nishes the greater part of the superficial plexus of the aorta which we have just described. This great right cardiac branch divides into two parts; the smaller passes between the aorta and pulmonary artery to reach the right side of the origin of the pulmonary artery, where it attaches itself to the right coronary artery to form the principal part of the right coronary plexus ; the other and larger portion creeps under the pul- monary artery to the posterior part of the heart, to assist in forming the left coronary plexus. The great left cardiac branch, which principally comes from the upper part of the cardiac plexus, and at first passes from right to left posterior to the ductus arteriosus, after which it is joined by other smaller branches which pass in front of the ductus arteriosus. It also divides into two branches ; the smaller passes between the aorta and pulmonary artery, and reaches the origin of the right coronary artery, and throws itself into the right coronary plexus ; the larger bends round the posterior surface of the pulmo- nary artery to reach the left coronary artery, where it forms, with the larger branch of the right, the left coronary plexus. There is thus a free interchange of filaments between the nerves of both sides. The left coronary plexus is considerably larger than the right, in propor- tion as the left side of the heart is thicker than the right. These coronary plexuses consist of a number of minute filaments which accom- pany the ramifications of the coronary arteries everywhere, and are distributed upon the sur- face of the auricles as well as upon the ventri- cles. They anastomose with each other upon the anterior and posterior surface of the heart. All the nerves of the heart enter into its sub- stance upon the surface of the arteries, and cannot be traced beyond the second or third division of the arteries. The nerves of the heart are generally considered to be small com- pared to the size of the organ.* Though the nerves of the heart are not equal in size to those of the tongue and eye, yet Scarpa is doubtful if they are not equal to the nerves of the other voluntary muscles, as, for example, the muscles of the arm. It must be remem- bered that the minute subdivision and diffusion of these nerves over a large extent of surface, by which many of them can only be seen after a minute examination, causes them to appear of less size than what they collectively really are. Soemmerring maintained that very few of the nerves of the heart were distributed to the mus- cular tissue of the heart, and that they more properly belonged to the arteries : " nervi car- diaci proprie ad arterias, ad aortam et arterias coronarias pertinent, eaque filia subtilia nervo- rum parum sibi (cordi) constant." \ Behrends, the pupil of Soemmering, affirmed that not a single twig went to the muscular tissue of the heart, but that they were entirely distributed on the coats of the arteries. J The announcement of these opinions, bearing so directly as they do upon the Hallerian doctrine of the nature of irritability, so keenly agitated immediately be- fore throughout Europe, could not fail to create considerable sensation at the time, and it is probable that to this we owe the splendid work of Scarpa upon the nerves of the heart, which has entirely set the question concerning the dis- tribution of these nerves at rest. Scarpa has shown that when followed to their minute dis- tribution, the nerves of the other muscles ac- company the arteries in the same manner as the nerves of the heart, and that the nerves of the heart only differ from those of voluntary motion in this, that the nerves accompanying the arteries of the voluntary muscles are firmer and thicker than those of the heart. Bloodvessels of the heart. — The heart is sup- plied with blood by the two coronary arteries, for a description of which see Aorta. The blood is returned by the coronary veins. The branches of the coronary veins generally accom- pany those of the arteries. They are divided into the larger coronary vein and smaller coro- nary veins. Great coronary vein (vena coronaria maxima cordis). — This vein is formed by several branches, three of which surpass the others considerably in size. One of these lies in the anterior longitudinal groove ; another runs along the obtuse or left margin of the heart ; and the third, which may be replaced by two or three * Bichat in his Anatomie Gencrale says, " that the nervous mass intended for the muscles of orga- nic life is much inferior to that of the voluntary muscles. The heart and deltoid muscle, on being compared together, display in this respect a very considerable difference." t Corporis humani labrica, torn. v. \ Dissertatio qua demonstratur cor nervis carere. After making this general statement, he admits, in one part of his treatise, that he has (raced two twigs of the cardiac nerves into the substance of the heart. HEART. 597 smaller veins, runs along the posterior surface of the left ventricle, between the obtuse margin and posterior longitudinal groove. The first of these is frequently described as the trunk of the vein, and it commences at the apex of the heart, where it anastomoses with the smaller posterior and anterior veins. It runs upwards in the anterior longitudinal groove along with the left coronary artery, gradually increasing in size as it ascends, from the junction of the other veins. When it reaches the base of the ventri- cles it changes its direction, enters the groove between the left auricle and ventricle, leaves the coronary artery, passes from left to right in the posterior part of the same groove, when it becomes considerably dilated ( sinus of the co- ronary vein ). It then opens into the right auricle at its lower and back part close upon the posterior edge of the septum aunculorum. Smaller posterior coronary vein (vena coro- naria cordis minor). — It commences at the apex of the heart, runs up in the posterior lon- gitudinal groove, or a little to its right side, and receives its blood principally from the right ventricle. It generally joins the sinus of the coronary vein ; at other times it enters the auri- cle separately immediately by the side of the great coronary vein, so that its aperture is also covered by the coronary valve. Smaller anterior coronary veins ( vents inno- minata of Vieussens). — These are very small and variable in number, and are placed on the anterior surface of the right ventricle. One of these, larger than the others, (generally the su- perior,) sometimes receives the name of ante- rior vein of Galen. They frequently unite to form a single trunk ; more generally perhaps they continue separate, pass in front of the right coronary artery as it lies in the auriculo-ventri- cular groove, and enter the right auricle at its anterior and inferior part. One of the musculi pectinati overlaps their entrance, forming a kind of valve. Vena minimis, or veins of Tltebesius, Sire minute veins, which enter the auricle at various points. It was maintained by Vieussens, The- besius, and Ruysch, that some of the coronary veins opened into the left side of the heart, thus producing a slight intermixture of the dark blood with the arterial. This has been more lately asserted by Abernethy* and has been supposed to occur more frequently in phthisical cases ; the difficulty of transmitting the blood through the lungs causes their enlargement. Such injections are liable to great fallacy, from the great facility with which fine injections, or even coarse injections when forcibly pushed into the vessels, escape into the cavities of organs. Especial care is, therefore, required in conducting them. Notwithstanding that we have the authority of some of the most accurate anatomists in favour of this opinion, it is very doubtful if any of these veins open into the left side of the heart.f * Philos. Trans. 1798. t Professor Jeffray (Observations on the Heart, &c. of the Foetus, p. 2) mentions a case in which the large coronary vein opened into the left auricle. Sinus of the coronary vein. — This is always described as a dilatation of the large coronary vein, but I have found it decidedly muscular in man and in several of the Mammalia, as the dog, horse, ox, and sheep ; and it presents the appearance of a muscular reservoir placed at the termination of this vein, similar to the auri- cles at the termination of the two cava;. This sinus is placed in the posterior part of the groove between the left auricle and ventricle, adheres intimately to the outer surface of the auricle, and communicates by one extremity with the auricle, and by the other with the large coronary vein. The commencement of the dilatation is generally abrupt, and the first appearance of the muscular fibres well defined. I have seen it vary from two inches to only half an inch in length. These muscular fibres are generally circular ; part of them, however, are oblique. Some of them belong exclusively to the vein ; a great part appear to be connected with the muscular fibres of the auricle. This muscular sinus must serve to prevent regurgi- tation along the coronary veins. I have also generally found a distinct valve at the termina- tion of the coronary vein in the sinus. This valve resembles the valves found in the veins of the extremities. It is generally single, some- times it is double. I have also occasionally found one or more single valves in the course of the vein.* A distinct valve may also occa- sionally be seen at the termination of the pos- terior coronary vein in the sinus. Portal f mentions that he has seen the coronary valve situated in the interior of the vein a little from its mouth. Thebesius and Morgagni have ob- served valves placed in some of the smaller veins where they terminate in the larger. The valves of the coronary veins do not in general prevent the passage of injections contrary to the course of the blood along them. Lymphatics of the heart. — The lymphatics of the heart are divided into two sets — super- ficial and deep ; the superficial commencing below the external serous membrane, and the deep upon the internal membrane. They fol- low the course of the coronary vessels. Some of them pass directly into the thoracic duct, and, according to Meckel, sometimes directly into the subclavian or jugular veins. Others pass into the lymphatic glands situated in front of the arch of the aorta, while others pass into the glands situated around the bifurcation of the trachea, and a few also join the lymphatic vessels of the lungs. Pericardium. — The pericardium is a fibrous Lecat (Mem. de l'Acad. des Scien. 1738, p. 62) found the coronary veins in a young child unite themselves into a single trunk and enter the left subclavian. It is probable that Soemmerring had this case in view when he states, " Rarissimc vena haec in vena subclavia dextra rinitur," (de corp. hum. fab. torn. v. p. 340, 1800 ) particularly as Haller, (Element. Phys. torn. i. p. 375, 1757), in quoting the case, has inadvertently substituted the word dextra for sinistra. * I have seen two or three pair of double valves in the course of the coronary vein in the horse and ass. These animals have no Thebesian valve. t Anatomie Medicaid, torn. iii. 598 HEART. bag surrounding the heart and origin of the large bloodvessels, but without any direct attachment to the heart itself, having its inner surface lined by a serous membrane. It is from this latter circumstance that it is generally termed a fibro-serous membrane. It is placed behind the cartilages of the second, third, fourth, and fifth ribs of the left side and middle part of the sternum. Posteriorly it rests upon the parts contained in the posterior mediastinum ; anteriorly it corresponds to the anterior medias- tinum, and may be reached by perforating the left side of the sternum, as has been proposed in some cases of hydrops pericardii. The pleurae adhere to its lateral and part of its anterior surface by pretty close cellular tissue, when the interposed tat is small in quantity. The phrenic nerves with their small accom- panying arteries pass down the thorax between the pleurae and lateral surfaces of the pericar- dium. Below, the fibrous part of the pericar- dium adheres intimately to the upper surface of the cordiform tendon of the diaphragm, and is also connected by pretty dense cellular tissue to the upper surface of the muscular fibres running into the anterior part of the left lobe of the tendon. It adheres more firmly to the cordiform tendon at the edges, particularly anteriorly, than at the centre. It is broader below where it adheres to the upper surface of the diaphragm, narrower above where it is attached to the large vessels that pass in and out from the heart. Upon these large vessels the fibrous part of the pericardium is prolonged, forming a kind of sheath, which gradually be- comes thinner until it is confounded with the cellular coat of the vessels. From the manner, however, in which the vena cava inferior enters the heart, it can have no fibrous sheath of this kind. At the different points where the fibrous coat becomes applied upon these vessels, and where the cava inferior passes through the cordiform tendon, the serous coat is reflected upon the outer surface of the vessels, and accompanies them back to the heart to cover the outer surface of that organ. In this man- ner the serous part of the pericardium is a shut sac, the outer surface of which adheres to the inner surface of the fibrous portion, and to the outer surface of the heart. The inner surface, like that of all the other serous membranes, is unadherent, smooth, and shining, and is every- where in contact with itself, and only contains the small quantity of fluid which serves to lubricate its interior. The serous portion of the pericardium adheres intimately to the inner surface of the fibrous. At that part, however, where the serous leaves the fibrous to pass back upon the surface of the large vessels, there is a small triangular space left between them. The serous membrane is reflected upon and covers the outer surface of the aorta rather more than two inches above its origin ; upon the pulmonary artery about the same distance and immediately before its bifurcation ; upon the cava superior about an inch above its entrance into the right auricle; upon the cava inferior shortly before it reaches the heart ; upon the two right pulmonary veins soon after they have emerged from the right lung; and upon the left pulmonary veins shortly before they enter the auricle. This serous membrane, in passing upon the aorta and pulmonary arteries, covers the anterior surfaces of both before it passes round upon their posterior ; it then en- velopes both arteries in the same sheath, so that their opposed surfaces are only separated from each other by a little cellular tissue. It leaves part of the posterior surface of the cavae and pulmonary veins uncovered, occasionally, however, enveloping the whole or nearly the whole, of the left pulmonary veins. It adheres but loosely to the large bloodvessels, and firmly to the outer surface of the auricles and ven- tricles. The attachment of the fibrous part to the cordiform tendon is very firm at the edges and blended with the tendon, but becomes looser towards the centre. Cloquet* describes the serous membrane as lying in contact with the upper surface of the cordiform tendon ; or, in other words, he appears to consider the fibrous part not to be prolonged over the upper surface of the tendon, but to stop at its attached margin. In most cases I have been able to trace the fibrous part of the pericardium over the upper surface of the cordiform tendon, but almost always more or less diminished in thick- ness. In some cases I was unable to detect anything like a fibrous layer at this part. The fibrous part of the pericardium is comparatively thin, and is composed of tendinous fibres interwoven together. It is not much larger than sufficient to contain the heart when its cavities are distended. This fact taken along with the physical properties of the membrane, not admitting of sudden dilatation, explains how the sudden escape of a small quantity of blood (8 oz. or sometimes less) into the interior of the pericardium is sufficient to arrest the heart's action. The arteries of the pericardium are small and come from various sources, from the bronchial, oesophageal, phrenic, from the arteries of the thymus gland, internal mammary, coronary arteries, and the aorta itself. Its veins partly terminate in the azygos, and partly accompany the corresponding arteries to terminate in the veins of the same name. Its lymphatics pass to the glands placed around the cava superior. The nerves can be traced into its texture. Uses of the pericardium. — The pericardium restrains within certain limits the irregular movements of the heart. The inner serous surface of the pericardium must also facilitate its ordinary and healthy movements. Relative position of the vessels within the pericardium. — The pulmonary artery at its origin overlaps the anterior surface of the aorta as it springs from the left ventricle. (See fig. 276, s, for the lelative position of these vessels at their * Traite d'Anatomie Descriptive, p. 633, trans- lated by Knox. Cloquet does not state distinctly that the fibrous part of the pericardium is not con- tinued over the cordiform tendon, but this may be inferred from the statement that the serous mem- brane " is applied below, directly and in a very close manner upon the aponeuroses of the dia- phragm." HEART. 599 origin.) It then proceeds into the concavity of the arch of the aorta, and as it is about to pass through the fibrous coat of the pericardium, it divides into its two branches, the right and left. The left branch passes in front of the descending portion of the arch of the aorta to reach the left lung; the right branch passes behind the ascending portion of the arch to reach the right lung. In the foetus the pulmo- nary artery divides into three branches, the two we have just mentioned, and a third, the ductus arteriosus, which unites the pulmonary artery to the descending portion of the arch, — in other words, after the aorta has given off the large branches to the head and superior extre- mities. The descending cava, immediately before it perforates the fibrous coat of the peri- cardium, crosses the right branches close upon the bifurcation of the trachea; within the peri- cardium it lies on the right side of the ascend- ing portion of the arch of the aorta. The inferior cava is seen perforating the cordiform tendon of the diaphragm, and almost imme- diately afterwards it enters the posterior and inferior angle of the right auricle. The pul- monary veins are placed inferior to the two branches of the pulmonary artery. The two right pulmonary veins pass behind the right auricle to reach the left, which they enter near the septum auriculorum. Peculiarities of the fatal heart. — (For an account of the developement of the heart and large bloodvessels see Ovum.) The heart of the foetus before the fourth month is placed vertically, but towards that period the apex begins to turn towards the left side. The auricular part of the heart is considerably larger in proportion than the ventricular. The relative size of the heart to the body at birth differs considerably from that of the foetus at an earlier period of its developement. According to Meckel the relative size of the heart to the body about the second or third month of uterine life is 1 to 50; at birth and for a few years afterwards as 1 to 120. The greater size of the heart of the foetus seems to depend principally upon the greater thickness of the walls of its cavities. The great disparity between the thick- ness of the two sides so very apparent shortly after birth does not exist in the earlier periods of uterine life, though also generally sufficiently well-marked in the foetus at the full time. This is explained by the circumstance that the two sides of the heart at this period have nearly equal obstacles to overcome in propelling the blood.* In the earlier stages of its deve- lopement the infundibuliform portion of the right ventricle is less prominent than at a later period. The left ventricle is at first a little larger than the right ; at birth and for a short while after they are equal. The two auricles communicate with eacli other through the fora- * In two foetuses, however, which I lately exa- mined, and where I had positive evidence that they had not yet reached the sixth month of utero- gestation, the difference between the thickness of the two ventricles of the heart was distinctly marked. men ovale.* This foramen is at its maximum size about the sixth month. Valve of the foramen ovale. — This valve, which, however, can scarcely be called a valve, as it is a provision for effecting the obliteration of the foramen ovale at the time the child assumes its independent existence, first makes its appearance at the lower part of the foramen about the third month, or, according to Senac and Portal, about the second month. It is formed by the inner membranes of the two sides of the heart, containing some muscular fibres between them, particularly at its lower part. It is of a semilunar form ; its convex edge adheres to a greater or less portion of the margins of the valve as its growth is more or less advanced; its concave margin, which is free and loose, looks upwards and forwards. This valve may be said to belong almost exclu- sively to the left auricle, as it is attached to that margin of the foramen. f Though this valve is of sufficient size at birth to shut the foramen, yet its concave or upper margin is easily depressed so as to leave a considerable interval between it and the upper margin of the foramen. We will find, from the man- ner in which the valve is attached to the left margin of the foramen, that it is much more easily depressed by a current passing from the right auricle into the left than in the opposite direction. In fact any force of this kind ap- plied in the opposite direction would rather tend to keep the valve applied to the upper edge of the opening; a circumstance which occurs after birth when the blood flows along the pulmonary veins into the left auricle, and which must materially assist in producing com- plete obliteration of the foramen. The manner in which the blood passes between the auricles through the foramen ovale in the foetus was the subject of a violent controversy in France at the termination of the seventeenth and the commencement of the eighteenth centuries. It was first commenced between Meri on the one side, who had proposed a new theory of the foetal circulation by which the blood was made to pass from the left auricle into the right, and by Duverry and Fauvery on the opposite side, who maintained the opinion of Ilarvey, and which is now universally adopted, that it passes from right to left. Many celebrated anatomists and mathematicians attached themselves to the opposite parties, and at last the controversy extended itself to the neighbouring kingdoms. J Eustachian valve. — This valve, the appear- ance and position of which have been already * This opening is frequently termed trou de Botal by the French writers though described by Galen. t This explains how the depression (fossa ovalis), marking in the adult the position of the valve, should be better seen from the right than the left auricle. | Those who may be anxious to acquaint them- selves more fully with the nature of this contro- versy and to examine the arguments adduced on both sides may consult the M ('moires de l'Academie for that period, and Senac's Traite de la Structure du Cceur, torn. i. p. 369, ajrd the Supplement in torn. ii. 600 HEART. pointed out in describing the interior of the right auricle, is also intimately connected with the peculiarities of foetal life. It was discovered by Eustachius about the middle of the six- teenth century, who contented himself by point- ing out its position. Little attention was paid to it until the commencement of the eighteenth century, when it was more particularly brought into notice by Boerhaave and Lancisi, who published a new edition of the works and plates of Eustachius, which had then become very scarce. Lancisi supposed that this valve prevented the blood of the superior cava from falling with too much force upon the column ascending by the cava inferior. Winslow,* finding it only perfect in the foetal state, and having cause to believe that its diminution kept pace with the increase of the valve of the foramen ovale, was led to adopt the opinion that its presence had a special reference to that state, and believed that it not only served to break the current of the superior cava as stated by Lancisi, but also opposed the regurgitation of the blood of the auricle into the inferior cava. In the absence of this valve he supposed there would arise two inconveniences in the foetus — the imperfect intermixture of the con- tained blood, and the regurgitation of the blood of the umbilical vein into the placenta. Senacf believed that the Eustachian valve can have no effect in preventing the blood of the cava supe- rior from falling upon the current ascending by the cava inferior, and that it must direct a part of the blood of the cava inferior through the foramen ovale. SabatierJ more particularly pointed out that from the position of this valve passing from the anterior and left part of the vena cava inferior to the left side of the foramen ovale, and from the situation of the foramen ovale at the inferior part of the auricle, the blood of the cava inferior must be directed through the foramen ovale ; and further, from the difference in the direction of the two cavae themselves — the superior looking downwards, forwards, and to the left side, while the inferior, though it is also slightly directed to the left, passes at the same time upwards and back- wards, when combined with the upper thick margin of the foramen ovale — it would neces- sarily happen that the blood of the superior cava must fill the right auricle. In three injections of the foetal circulation which I performed, where arrangements were made to imitate, as far as possibly could be done, the manner in which the two currents flow into the heart during the life of the foetus, results were obtained confirmatory of the opi- nion of Sabatier.§ This arrangement cannot of course exist in the early months of uterine * Memoires de l'Acad. Roy., annee 1717. t Op. cit. torn. i. p. 228. t Traite complet d'Anatomie, torn. ii. p. 224. § Edinburgh Medical and Surgical Journal, 1835. These injections are also confirmatory of one made by Kilian, where the fluid thrown along the aorta passed to the head and superior extremities, and that along the pulmonary artery to the lower part of the body. life from the imperfect developement of th e heart itself, and in all probability part only of the blood of the inferior cava is transmitted through the foramen ovale into the left side of the heart for a short time before birth. The pulmonary veins appear to bring very little blood to the left side of the heart until the time approaches that the foetus must necessarily assume an independent existence. The circu- latory apparatus becomes gradually prepared for this change ; — the Eustachian valve begins to shrink, the foramen ovale to diminish in size, and a greater quantity of blood is transmitted through the lungs. Billard* has ascertained from the examination of the bodies of a great number of infants who died within a few days after birth, that the foramen ovale and the other circulatory passages peculiar to the foetus are generally shut about the eighth day after birth. In nineteen infants who had lived only one day the foramen ovale was completely open in fourteen ; in two it had commenced to become obliterated, in the remaining two it was com- pletely shut. On the subsequent days the number of those with the foramen shut con- tinued to increase; and in twenty examined, who had died on the eighth day, five only had the foramen open. Physiology of the heart. Mode of action of the valves of the heart. — While the blood is rushing through the auri- culo-ventricular openings during the contrac- tion of the auricles, the lips of the mitral and tricuspid valves are separated from each other and thrown outwards from the axis of the opening, and the larger lip of both is at this time carried towards the arterial orifices. It has generally been supposed that the mitral and tricuspid valves are, during the systole of the ventricles, passively floated up towards, and obstruct the auriculo-ventricular orifices so as to prevent the free regurgitation of the blood into the auricles ; and that the use of the cordse tendmese is merely to limit the movements of the valves, — to permit them to be raised suffi- ciently to close the orifices, but at the same time to provide against the otherwise unavoid- ably fatal consequences that would result from these unresisting valves being carried through into the auricles by the current of blood. Mayo, Bouillaud, and others have, however, main- tained that the lips of these valves are not approximated in the mechanical manner just stated, but by the contraction of the musculi papillares of which the cordae tendineae are the proper tendons. As the musculi papillares contract along with the other fibres of the ven- tricles, the lips of the valves are drawn towards the axis of the opening, and are closely applied to each other, forming a kind of cone, the apex of which projects downwards into the ven- tricles. Jt is from the adoption of these views that Bouillaud proposes to call these musculi papillares, the tensor, elevator, or adductor muscles of the valves. That the lips of the * Traite des Maladies des Enfaas nouveau-nes, &c, p. 557, 1828. HEART. 601 valves are approximated in this manner appears to me to be the much more probable opinion; for when we examine the uniform position and course of the musculi papillares and chords tendineae, more particularly those of the left ventricle ; that the chordae tendineae pass from each musculus papillaris to both lips of the mitral valve, occasionally crossing each other ; and that the posterior or smaller lip, though it may be drawn inwards so as to meet the larger and more moveable, is so bound down as to be scarcely capable in most cases of being floated up on a level with the orifice ; and further, when we also remember that the mus- culi papillares contract at the same time with the other fibres of the heart, we can scarcely resist coming to this conclusion. Besides, if the lips of the valves were floated up to the orifice, a greater quantity of blood would regur- gitate into the auricles during the systole of the ventricle than in all likelihood takes place ; for as the lips of the valve must be widely separated from each other when the systole commences, it is evident that a less quantity of blood must have passed through the orifice before the lips are sufficiently approximated to obstruct its further passage when these are assisted by an active force, than when they are merely passively brought together by the cur- rent of blood passing in that direction. It has, however, been supposed that the musculi papillares do not contract with the other fibres of the ventricles. Ilaller states* that on laying open the heart he has seen the muscles of the valves contract during the systole of the heart. It may be objected to this experiment that the unusual stimulus applied to the heart in cutting its fibres across may have deranged the usual order of its contractions. I have repeatedly opened the heart in rabbits and waited until its contractions had ceased, and on renewing its movements by irritating the inner surface at a distance from the cut edges, I have observed that the columns; carneae acted simultaneously with the other muscular fibres of the heart.f I was also satisfied that the musculi papillares were proportionally more shortened during their contraction than the heart itself taken as a whole, which is nothing more than what we would expect when we remember that the fibres of the musculi papillares are so far free and run longitudinally, while by far the greater part of the other fibres run in a spiral manner. Haller, in relating his observations on the contraction of the musculi papillares, makes another statement, which, however, is decidedly adverse to this opinion. The chordae tendineae appeared to him to be relaxed during the con- traction of the musculi papillares. It is difficult to make satisfactory observa- tions upon the effects of the contractions of the * Elemcnta Physiolog. torn. i. p. 390. Sur le Mouvement du sang, p. 129. Memoires sur la Nature sensible, torn. i. p. 379. t [The observations of the London Committee appointed by the British Association to examine into the motions and sounds of the heart confirmed this view of the simultaneity of contraction of the columns; caruca; and ventricular fibres. — Ed.] musculi papillares upon the tension of the chordae tendineae. In several animals upon which we attempted to ascertain this, it was only when the heart was acting languidly that we could observe what was likely to be the effect of the contraction of the musculi papil- lares on the chordae tendineae when they were placed as far as possible in their natural rela- tion to each other. We could never observe that they contracted sufficiently to move the valves, but they certainly rendered some of the chordae tendineae more tense. When, however, we take into account, that in an experiment of this kind, the valves are not thrown out widely from the orifices of the auriculo-ventricular orifices, the ventricle is not distended with blood, the chordae tendineae consequently not put so far on the stretch as occurs at the com- mencement of the systole, and that the con- tractions of the musculi papillares are languid, we can easily perceive how, in the natural systole of the heart, these contractions of the musculi papillares should be sufficient to move the valves inwards, though not to such an extent as to apply them closely to each other. The con- traction of these musculi papillares apparently sets the valves in motion, and they are subse- quently applied to each other by the currents of blood. It may be supposed that if the con- traction of these musculi papillares can render the chordae tendineae sufficiently tense to move the valves, this would prevent the subsequent elevation of them to obstruct the auriculo- ventricular opening. We believe, however, that it is only at the commencement of the systole that they are sufficiently tense to move the valves, for as the contraction proceeds the capacity of the heart is so much diminished, both in its transverse and longitudinal dimen- sions, that they become relaxed. Besides, if we could suppose that these musculi papillares are capable of contracting through a sufficient space to draw the valves together, this would be all that is necessary to prevent the regurgita- tion of the blood through the auriculo-ventri- cular opening.* So convinced, indeed, were the older anato- mists and physiologists that the chordae tendineae are relaxed during the systole of the heart, and of the necessity of an accompanying diminution of the length of the ventricles themselves to effect this, that this argumentadduced by Bassuel appears to have been principally instrumental in deciding the once keenly controverted ques- tion whether or not the heart was elongated during its contraction.y * All these experiments upon the action of the columnar carneae were finished and the article forwarded to London about the middle of June, 1836. f Mr. T. W. King in an elaborate essay (Guy's Hospital Reports, No. iv. April 1837,) has pointed out what he conceives to be a " safety-valve func- tion in the right ventricle of the human heart." This view is founded upon the fact which he be- lieves that he has ascertained, " that the tricuspid valve, naturally weak and imperfect, closes less and less accurately, according to the increasing degrees of the ventricular distention." From this he is " convinced that, in all cases in which the 602 HEART. It may be supposed that the relative size of the auriculo-ventricular orifices to the length of the lips of the valves would not admit of their apices being brought together in the form of a cone as described, but it must be remembered that from the course of the muscular fibres in the immediate neighbourhood of those open- ings, their areas must be diminished during the systole of the heart. There is at least one thing certain connected with the action of these valves, viz. that the contraction of the musculi papillares can never cause the valves to strike the inner surface of the ventricle and produce a sound as has been supposed. The manner in which the semilunar valves at the origin of the aorta and pulmonary artery perform their office is entirely mechanical and easily understood. During the systole of the heart they are thrown outwards from the axes of these vessels ; but during its diastole, when part of the blood driven into the artery would fall back into the ventricles, these valves are thrown inwards and obstruct completely the whole calibre of the arteries. In all probability the sinuses of Valsalva placed behind these valves contain a certain quantity of blood even during the systole of the heart, and this re- acting upon the valves through the agency of the elast.city of the arteries brought into opera- tion at the termination of the systole, materially assists in producing the more rapid and certain action of the valves. Movements of the heart. — The heart is a muscle of involuntary motion, being, for the wisest of purposes, placed beyond the direct control of volition. The case of Colonel Townshend* is of too obscure a nature to entitle us to found upon it an opposite doc- trine, more particularly as it is at direct variance with every other fact or observation. The movements of the heart, when the body is at rest or in a state of health, proceed with- out our consciousness. In certain cases of disease they are attended by uneasy feelings, but they are never at any time or under any circumstances dependent upon sensation for their continuance. It is not so easy a matter as may at first be imagined to ascertain the order of succession in which the different cavities of the heart con- tract and dilate, and the different circum- stances which attend these movements, even by experiments on living animals, more par- ticularly the warm-blooded animals ; for if the heart when exposed is acting vigorously and rapidly, every one who has examined for him- self must have felt the exceeding difficulty of following and analysing these movements by right ventricle is, in any material degree, tempo- rarily distended or permanently dilated, the heart and lungs are relieved by a considerable reflux of the ventricle's contents into the auricle and sys- temic veins." In experiments upon the lower animals I have repeatedly seen the right ventricle, when gorged with blood and acting feebly, empty itself through an opening in the jugular vein. Bdinb. Med. and Surg. Journ. 1836. * Cheyne's English Malady, p. 307. 1734, London. the eye. If, on the other hand, the animal has become debilitated and the movements of the heart languid, these are apt to deviate from their natural order, and to be performed in an irregular and unnatural manner.* It is in this way that, we can account not only for the dis- crepant statements of the older observers, but also for the very frequent announcement of new views on this subject which appear in the medical periodicals of our own day. As we will find that many of these theories connected with the physiological actions of the heart even in the present day, have been founded upon false notions of the normal anatomy and na- tural movements of the organ, and only require a reference to these for their full and satis- factory refutation, it will be necessary that we attend particularly to the manner in which these different contractions and relaxations suc- ceed each other, and the visible phenomena by which they are accompanied, as observed by the most accurate experimenters. When the heart of a living animal is ex- posed and the organ is acting in a natural manner, the auricles are observed to become distended with blood, then to contract rapidly and simultaneously, and propel part of it into the ventricles; this is accompanied with a corresponding enlargement of the ventricles, which is immediately followed by their simul- taneous contraction and the propulsion of their blood along the large arteries : then follows a pause, during which the auricles become gra- dually distended by the blood flowing along the veins. When the auricles are filled, they again contract, and the same train of pheno- mena just described occur in uniform succes- sion. Systole and diastole of the auricles. — The contraction or systole of the auricles is pre- ceded by their relaxation or diastole. During the diastole the auricles become distended with the blood flowing along the veins. The com- mencement of the diastole occurs during the contraction of the ventricles; the latter part corresponds to the pause in the heart's action, and to the interval between the recurrence of the sounds of the heart, and is more or less long in proportion as the blood flows more or less rapidly along the veins. The systole of the auricles is performed with great rapidity when the action of the heart is still vigorous, and appears to be effected by the simultaneous contraction of all its fibres. The terminations of the cavae and pulmonary veins are seen to contract simultaneously with the fibres of the auricles, but sometimes they are seen to contract previous to the auricles, into which they expel their blood. In the cold- blooded animals this contraction of the ter- minations of the large veins extends over a greater surface, and is visible in the venae he- * The illustrious Harvey thus describes the dif- ficulties which he experienced in his first attempts to analyse the movements of the heart : " ita ut modo hinc systolem, illinc diastolem, modo c con- tra, modo varios, modo confusos fieri motus me existimarem cerncre." HEART. 603 paticae.* Judging from the number of mus- cular fibres which surround the termination of the pulmonary veins in the human species, we would expect these contractions to occur to a greater extent in these veins than in the cava?. These contractions in the veins must assist the vis a tergo, or the force with which the column of blood flows along the veins towards the heart, in limiting the regurgitation along these during the contraction of the auricles. This regurgitation along the veins appears to be to a small extent only when the circulation is pro- ceeding in a natural manner, but becomes con- siderable where there is any impediment to the free passage of the blood into the ventricles, and when the blood becomes stagnated in the veins. When the actions of the heart are en- feebled, the contractions of the auricles are slower, and may become more or less vermi- cular, as I have myself occasionally observed. Two or more contractions of the auricle may also now be necessary before the languid ven- tricle can be excited to contraction. When the action of the heart is still more enfeebled, particular portions only of the auricles con- tinue to contract. According to the obser- vations of Harvey, Lower, Senac, Ilaller, and others, the contractions of the auricles are per- formed with considerable force. Harvey states that he has observed that if the finger is applied to the ventricles in those cases where the action of the auricles continues after the contractions of the ventricles have ceased, a distinct beat is felt in the ventricle at each stroke of the auricle ; and Senac, in quoting this, adds (evidently from his own observation) that it is similar to the pulse in the arteries. Senac also states that if an opening be made into the apex of the heart under those circum- stances, a jet of blood rushes through it at each stroke of the auricle. He, however, admits that the contraction of the auricles in these cases is not sufficient to dilate sensibly the walls of the ventricles, but, of course, very considerable allowance ought to be made for the enfeebled state of the auricles at this stage of the experiment.-)- In the experiments of Dr. Hope, Mr. Carlisle, M. Bouillaud, and the Dublin Committee for investigating the cause of the sounds of the heart, the contrac- tion of the auricles appeared to be compara- tively trifling, and was most apparent in the appendices. From my own observations upon rabbits and dogs I am convinced that the au- ricles contract considerably more when the movements of the heart are proceeding in a natural manner, than some of these last expe- riments would lead us to believe, and that this contraction is not confined to the appendix, * The contractions of the different parts of the heart in cold-blooded animals have been observed to occur in the following order : first, the termin- ation of the large veins, then the auricles, then the ventricles, and, lastly, the bulb of the aorta. f I have convinced myself of the accuracy of these statements of Harvey and Senac in expe- riments upon dogs opened soon after they had been deprived of sensation. but extends over the whole auricle. When the circulation through the lungs becomes im- peded, the right ventricle is then unable to empty itself, and the auricle of the same side (and this is the one that is most generally ob- served in such experiments) is consequently impeded in its movements. The auricles do not certainly exert the force or contract to the extent which some have stated, do not ex- pel the whole of their contents, and their diastole is comparatively feeble; but that none of the muscular fibres of the auricles are pas- sive, but exert a force proportionate to their strength, we have evidence both from expe- riment and the effects of disease. In some of those cases where an impediment to the passage of the blood from the auricle to the ventricle exists, all the muscular fibres of the auricles become much increased in thickness and in strength. As the left auricle has natu- rally greater difficulties to overcome in pro- pelling its blood than the right, so we find that the left auricle is considerably more muscular than the right.* The appendix from its being loose, and supplied by a band of longitudinal fibres drawing it backwards, must enjoy a freer motion than the other parts of the auricle. Systole and diastole of the ventricles. — When the heart is acting vigorously, the con- traction of the ventricles succeeds immediately upon that of the auricles, so that they some- times appear continuous ; or, in other words, the sudden distention of the ventricles by the blood propelled into them during the systole of the auricles is rapidly followed by the con- traction of the ventricles. The systole of the ventricles must occur during the diastole of the auricles. As we are only sensible of the sys- tole of the ventricles from external examination during life, the expression systole of the heart is always employed as synonymous with the systole of the ventricles. When the action of the heart is a little less active, an apparent in- terval is observable between the completion of the contraction of the auricles and the com- mencement of the contraction of the ventricles, — the irritability of the ventricles being at this time somewhat impaired, their contraction does not so quickly follow their sudden distention. The ventricles during their systole are dimi- nished in all their dimensions ; the apex is drawn upwards to the base and tilted forwards so as to strike the parietes of the thorax be- tween the cartilages of the fifth and sixth ribs.f " In the case mentioned by Allan Burns, where an ossific deposit covered the whole surface of the ventricles, so as to entirely, or nearly entirely, pre- vent their action, the auricles must have per- formed part of their functions for some time before death. In one of the experiments of Dr. Wil- liams, of London, upon asses, he observed the circulation along the arteries continue although the ventricles were quiescent, and the auricles alone contracted. t " Dr. C. J. 13. Williams has, in a lecture lately published in the Medical Gazette (July 28, 1838, p. 692,) pointed out that, during a deep inspira- tion, the ribs are elevated without raising the heart in the same degree, and the impulse may be felt G04 HEART. The parietes of the ventricles at this time are firm and resisting, and present some rugae on their outer surface. Mailer* states that though the principal movement of the ventricles du- ring their systole is from the apex upwards, yet he has sometimes observed a slight but dis- tinct movement from the base downwards. The contraction of the ventricles is performed with great force, and, when vigorous, appears to be accomplished by the simultaneous action of all its fibres ; but at other times, when it has be- come enfeebled, it has been observed to com- mence at the apex and extend itself upwards. The diastole of the ventricles consists of two distinct stages. The first, which immediately follows its systole, is sudden, the apex being pushed downwards and apparently passing deeper into the chest, and is occasioned by the return of the heart to its state of rest. The second is also sudden, and attended by a rapid but not very extensive enlargement of the heart in all its dimensions. The parietes of the heart are soft and flaccid, and their external surface smooth during their diastole. The diastole of the heart is performed with con- siderable force, so that Pechlin, Perrault, Ham- berger, and others long ago maintained that this equally with the systole is the result of a vital action. This opinion was again revived by Bichat, Dumas, and their followers, and is still introduced by some into the discussions upon the movements of the heart. Before we can admit an opinion of this kind, it would be necessary that very strong evidence be adduced in its favour, as it is at perfect variance with all that we know of the arrange- ment of the fibres of the heart, and of the laws of muscular contractility .f OesterreicherJ has performed the following experiment, which appears nearly decisive on this point. When a body is placed on the heart of a frog heavy enough to press it flat, but sufficiently small to allow the heart to be observed, it will be seen that the body will be lifted during the contraction of the heart, but that during its extension it will remain flat. From this it appears that the extension of the heart after the contraction is not a muscular act. The diastole of the heart depends then upon two circumstances. 1st, Upon the na- tural elasticity of the organ, which it possesses in common with every other muscle, and by which it instantly resumes its state of rest as soon as its contraction has ceased. This, which is usually termed the relaxation of a muscle in whatever part of the body it occurs, must be expected to be more energetic in the heart than below the sixth rib. On the other hand, when the ribs are depressed, as during a deep expiration, the apex of the heart may be felt beating between the fourth and fifth ribs." * El. Phys. torn. i. p. 400. t Scharschmid supposed that certain pretended longitudinal fibres^by shortening the heart enlarged its cavities, while the transverse fibres by contract- ing separately diminish its capacity. t Muller's Handbuch der Physiologie des men- schen, Erster Band, p. 163. in the muscles of voluntary motion, as from the arrangement of its fibres a great part must be more strongly compressed. This occurs during the first of the two stages into which we divided the diastole. 2d, Upon its sudden distention during the contraction of theauricles, when we have every reason to believe that the ventricles are completely passive. This con- stitutes the second stage of the diastole. The blood must then pass from the auricles into the ventricles during each diastole at two dis- tinct periods of time, corresponding to these two stages. During the first stage, or the re- laxation of the ventricles, it flows from the auricles to fill up the vacuum produced in their interior; while, during the second stage, it is forcibly propelled by the auricles. It would be difficult to estimate the relative proportion of these two quantities of blood. Those who suppose that the contraction of the auricles is feeble must consequently believe that most of the blood passes from the auricles into the ven- tricles during the first stage. It has been long disputed whether or not the ventricles empty themselves completely during each systole. It is very difficult to perceive anything like correct data upon this point in the warm-blooded animals with opaque hearts ; but reasoning from analogy, from what we see in the cold-blooded animals whose hearts be- come quite pale during each systole, (not, as Harvey supposed, from the blood being pressed out of its parietes, but from the blood in its cavity, seen through its transparent sides, being almost entirely expelled during its systole,) we would be inclined to believe -that little blood remained after each systole in the active state of the organ, while we can easily sup- pose that a greater or less quantity is left after each contraction when the organ is less vi- gorous. It was the subject of a violent dispute at the commencement of the last century between the Montpellier and Parisian anatomists and phy- siologists, whether or not the heart became shortened or elongated during its contraction. In all the warm-blooded animals at least it undoubtedly becomes shortened.* We may at the same time state that the obliteration of the cavity of the ventricle depends much more upon the approximation of its sides than the drawing up of the apex. Impulse of the heart. — It has been at various times, and still is by some late and modern experimenters,f maintained that the apex of the heart strikes the parietes of the thorax during * The authority of Harvey has been quoted in favour of the opinion that the heart becomes elon- gated during its contraction, and certainly in one part of his work it is distinctly stated, that it is so to a certain extent : " Undique contrahi magis vero secundum latera ; ita uti minores magnitu- dinis et longiuseulum , et collectum appareat." t Pigeaux, Stokes, Burdach, and Beau. Br. Corrigan has, much to his credit, publicly re- nounced his previously published opinions on this question, after more accurate observations had con- vinced him of his error. HEART. 605 its diastole, and not during its systole. This is in reality what we would a priori expect, for it certainly does at first appear somewhat paradoxical that the heart should strike the parietes of the chest when the apex is ap- proximated to the base. The concurrent tes- timony of the most accurate observers has, however, fully established the correctness of the fact. Harvey observed it in the human body when the heart had been exposed from the effects of disease.* One of the principal arguments adduced in support of this opinion by these authors was drawn from the fact that the pulse at the wrist is not synchronous with the impulse against the chest, an opinion which had been pretty generally maintained since the time of Aristotle. It is difficult to be convinced of this when the pulse is quick ; but when it is slow, and in certain cases of disease of the heart, it can generally be satis- factorily ascertained. So far then they are right, but in the next and most important step of the argument they fall into a decided error ; for they proceed upon the supposition that the pulse is synchronous in all the arteries of the body at the same time, and consequently the impulse of the heart at the chest cannot be synchronous with the flow of blood along the arteries, or, in other words, with the systole of the heart. In opposition to this opinion, Dr. Youngf had previously shown upon the principles of hydraulics that the pulse along the arteries must be progressive, yet in general so rapid as to appear to arrive at the extremities of the body without the intervention of any perceptible interval of time. And when the attention of medical men was turned to this subject, various observers soon ascertained by repeated experiments that the pulse could be felt in favourable cases to pass along the arteries in a progressive manner, — that the pulse in the large arteries at the root of the neck and impulse at the chest are synchronous or nearly so, that both precede that at the wrist, and more distinctly still that of the dorsal artery of the foot.J Various attempts have been made to explain * " Simul cordis ipsius motum observavimus, nempe illud in diastole introrsum subduci et retrain ; in systole vero emergere denuo et protrudi fierique in corde systolem quo tempore diastole in carpo percipicbatur : atque proprium cordis motum et functionem esse systolem : deniqne cor tunc pectus fierique et prominulum esse cum erigitur sursum." As quoted by Shebeare, Pract. of Phy- sic, vol. i. p. 195. f Phil. Trans. 1809. \ Ft is interesting and curious, as shewing the revolution of opinions, to compare the strict simi- larity of the arguments adduced by the modern supporters of this doctrine with those maintained by Shebeare in 1755. (Practice of Physic, vol. i. p. 193.) " This, however plausible it may ap- pear, cannot be the true cause of it (impulse of the heart), because then this stroke must be during the systole of the ventricles, which would be syn- chronous with the diastole of the arteries ; whereas the beating of the heart precedes the dilatation of the arteries, and thence this stroke must be made dining the diastole of the ventricles : thus the diastole or distention of the heart is the cause of the beating against the ribs." in what manner the apex of the heart is made to impinge against the parietes of the chest by those who maintain that it occurs during the systole of the ventricles. Senac supposed that this was principally effected by the curvature of the two large arteries, but principally of the aorta, which arise from the ventricles ; for at each stroke of the ventricles when an addi- tional quantity of blood is driven into the large arteries, as they are curved they make an at- tempt to straighten themselves; and as this takes place to a slight extent, the heart, which is attached to their extremities, ought to be displaced, and its apex, which describes the arc of a circle greater than the other parts of the heart, is thus made to impinge against the walls of the chest. He also believed that the distention of the left auricle with blood during its diastole has also, from its position between the spine and base of the heart, the effect of pushing the heart forwards; and this occurring at the same time with the attempt which the curved arteiies make to straighten themselves, it thus acts as a second or subsidiary cause in tilting the heart forwards* Though this sup- posed effect of the curvature of the large arteries has been a favourite explanation with many of the impulse of the heart against the chest, yet it really appears to have little, if any, influence in producing this. Shebeare,f and, more lately, Dr. C'orrigan,+ have shown that the direction of the curvature of the large ar- teries is such, that if any effect of this kind is produced, the heart would not be carried to the left side, but in the direction of the curve, which is exactly in the opposite direction. Besides the tiltmg forwards of the heart has been observed though no blood was passing along the large vessels at the time, and the same thing takes place after the large vessels have been cut through and the heart removed from the body.§ Haller and others have sup- posed that the secondary cause assigned by Senac, — viz. the sudden distention with blood of the left sinus venosus which lies impacted between the spine and left ventricle, — is the principal if not the sole cause by which the heart is pushed forwards against the ribs. In confirmation of this opinion Haller states || that if we inflate the left auricle after having opened the chest, we see the point of the heart approach with vivacity the region of the mam- ma. As we cannot, however, under these cir- cumstances distend the auricle without also distending the corresponding ventricle, this movement of the heart depends more upon the sudden inflation of the ventricle than upon any * Op. cit. torn. i. p. 356. The cause of the tilt- ing motion of the heart was also, at a later period, attributed to the curvature of the aorta and to this exclusively by Dr. W. Hunter. Note in John Hun- tor's Treatise on Inflammation, p. 146, 1794. t Op. cit. p. 195. % Dublin Med. Trans, vol. i. p. 154. § Dr. Carson (Inquiry into the Causes of the Motion of the Blood, p. 183,) maintains that no proof can be adduced that the curvature of the aorta is rendered more straight during the systole of the heart. || Sur le Mouvemcnt du Sang, p. 124. 606 HEART. distention of the auricle, as any one may easily satisfy himself by repeating the experiment. Besides, the distention of the auricles by the blood flowing along the veins is too gradual for this sudden and rapid impulse of the heart ; nay more, — the impulse may be observed when no blood is flowing into the auricles. Sabatier* believed that this impulse depends upon two causes, — 1st, principally upon the distention of the auricles, more particularly the left; and, 2dly, upon the curvature of the large arteries. Apparently, however, perceiving the necessity of there being a sudden distention of the auri- cles to produce this, he supposed that this was effected by the auriculo-ventricular valves. He argued that, as these valves during the diastole of the heart form a cone stretching from the base towards the point of the ventricle, which is full of blood when the systole commences, when the valves are carried upwards to ob- struct the auriculo-ventricular orifices, this blood is pushed before them into the auricles, producing a reflux into the auricles, which, with the blood flowing along the cava; and pul- monary veins, causes a sudden distention of the auricles, which pushes the ventricle forwards. f Meckel appears to have adopted the opinions of Sabatier. We need not repeat our objec- tions to this explanation. Dr. Alison, per- ceiving the insufficiency of all these explana- tions, has for a considerable time past sug- gested in his lectures, that this might be ex- plained by the arrangement of the fibres, " more particularly by the irregular cone which they form, being Jluttened posteriorly, and by the consequent greater mass of fibres on the anterior surface." More lately Mr. Carlisle + has also attempted to explain this by the greater length of the anterior fibres of the heart than of the posterior. As the shape of the ventricles is an oblique cone, and as they have their long- est sides in front, he argues, " that it is a law of muscular contraction that fibres are shortened during their contraction in proportion to their length when relaxed. For instance, if a fibre one inch long lose by contraction one- fourth of its length, or one quarter of an inch, a fibre two inches in length will lose one inch by contractions of equal intensity. The apex then does not approach the base in the line of the axis of the ventricles, but is drawn more to the side of the longer fibres, that is, towards the front, thus producing the tilting forwards." We believe that it may be proved on mechani- cal principles, that though the anterior and left surfaces of the ventricles are considerably longer than those on the posterior and right, yet during their contraction, when they are drawn towards their fixed attachments, if the fibres are of equal thickness, the apex will be drawn up nearly in the diagonal of the two forces, and that if any tilting upwards of the apex take place, this will be only to a small extent, and * Traite complct d'Anatomie, torn. ii. p. 230. t Dr. Bostock has failed of his usual accuracy in detailing the opinion of Sabatier on this ques- tion. X Transactions of British Scientific Association, vol. iii. Dublin Journal of Medical Science, vol. iv. be quite insufficient to account for the impulse felt at the chest. We must therefore look to some other circumstances besides a mere diffe- rence in length of the two surfaces to account for this. Mr. Alderson* has ingeniously at- tempted to apply the law of action and reaction between bodies, — one of considerable import- ance in mechanical philosophy, and upon which Barker's centrifugal mill has been constructed. Unfortunately, however, for this explanation, the axes of the large arteries and the direction in which the apex is tilted do not by any means accord. Dr. Hope's supposition that " the re- tropulsion of the auricular valves" may assist in producing this impulse, " as these act on a column of blood which offers a greater resist- ance than the weight of the heart, the action is reflected on the organ itself and impels it for- wards," is, on the other hand, completely op- posed to the law that action and reaction are the same. As well may a man attempt to pro- pel a boat by standing in the stern, and push with an oar against the prow. Dr. Filhos attri- buted the impulse to the spiral turns of the fibres at the apex of the heart attempting to straighten themselves during their contraction, and so raise themselves suddenly and throw themselves forwards. The objections to this explanation are so palpable that they must occur to every one. Since the tilting of the apex of the heart forwards is observed after the blood has ceased to flow through its cavities, it is obvious that we must look for the cause of this in the arrangement of the muscular fibres themselves, though it may be difficult to point out that particular arrangement. It appears to me that the distribution of some of the strong bands of fibres, the course of which I have already described when treating of the muscu- lar tissue of the heart, may satisfactorily account for it. We there pointed out that several strong bands of fibres arise from the base of the septum between the ventricles, pass downwards and form part of the septum, then emerge from the anterior longitudinal groove {fig. 274, d ), and wind round in a spiral manner to form both the anterior and posterior part of the lower portion of the heart. On entering the apices of the ventricles, (principally the left,) the fibres are scattered over their inner surfaces, and while a great number of them go directly to be inserted into the tendinous rings, others form part of the columnar carnea?. We have thus strong bands of fibres attached by one extremity (their septal extremity) to the base of the ventricles at a point pretty far posterior, while at the other ex- tremity many of the fibres are loose, or at least only attached to the tendinous rings through the media of the chordae tendinea? and valves, which must admit of a certain degree of con- traction of these fibres before they become tense. At each systole of the heart when these fibres act, it is evident that the tendinous rings must form the fixed points towards which all these fibres contract ; and since they are by one ex- tremity all closely and directly connected to a * Quarterly Journal of Science, &c. vol. xviii. p. 223. fixed attachment, viz. the tendinous rings, while by their other extremity part only are directly attached to the tendinous rings, the other part being loose, or at least only connected to the tendinous rings through the lax chorda? tendi- nea and valves, it must follow that the force with which the contraction takes place towards the septal extremity must preponderate over the other. If these bands of fibres had been as closely connected to the tendinous rings at the one extremity as at the other, then the force of the contraction towards both would have been equal ; but since this is not the case, the apex must be carried forwards at the same time that it is drawn upwards towards the base. This forward motion may also probably be assisted by another arrangement of the same fibres which we have been describing; for some of these muscular bands are attached by their inner extremity to the anterior part of the left auriculo-tendinous ring, so as to form loops, the greater part of which lie more in front than be- hind the axis of the heart, and may have a ten- dency, when in a state of contraction, to draw the apex forwards and upwards. Now when we remember that by this elevation of the apex forwards, the heart, before placed obliquely, now becomes more horizontal, and conse- quently more approximated to the walls of the chest, — the more particularly as the transverse diameter of the chest diminishes rapidly as we proceed from below upwards, we believe that we have here sufficient to account for this im- pulse against the chest. As the proximity of the apex of the heart to the chest is affected by the position of the body, as we have already pointed out, this circumstance ought to be at- tended to in judging of the strength of the im- pulse of the heart. What parts of the heart most irritable. — The inner surface of the heart is considerably more irritable than the outer. In experiments, when the heart has become quiescent, and refuses to obey a stimidus applied to the outer surface, it frequently contracts readily for a short time after this when air is introduced into its cavi- ties, or when any other stimulant is applied to its inner surface. After death the different cavities of the heart generally lose their contrac- tility in the following order, the left ventricle, the right ventricle, the left auricle, and last of all the right auricle.* And as the heart is gene- rally the part of the body which shews the latest evidences of contractility, the right auricle has long received the name of ultlmum moriens. Ualler supposed that the greater persistence of contractility in the right side of the heart over the left might depend on the circumstance that the right side of the heart generally contains a greater or less quantity of blood after death, while the left side is generally empty. In this * There is occasionally considerable variety ob- served in the order in which the different cavities lose their contractility after death. The left ven- tricle has been seen to contract after the right auri- cle ; and Haller has observed in experiments upon cats the irritability of the left auricle first cease. In experiments upon dogs I have seen the ventri- cles contract after the auricles had ceased to do so. 607 HEART. manner the inner surface of the right side of the heart is subject after death to the presence of a stimulant from which the left side is compara- tively free. He put this opinion to the test by performing repeatedly the following experi- ment* He emptied the right side of the heart by the section of the pulmonary artery and venae cava, having previously retained the blood of the left side by passing a ligature around the aorta. The experiment succeeded many times : the right auricle remained per- fectly immoveable, and the only motion which the right side retained arose from the connexion of its fibres with those of the left ventricle. The left auricle retained its movements for a certain time, the ventricles during a longer period, sometimes even for two hours. He adds, we thus transfer from the right auricle to the left ventricle the property of being the last living part in the body, in preserving for it during a longer period the irritation produced by the contact of blood. These experiments of Haller certainly shew that the left side of the heart will continue to contract longer than the right where it is subjected to a stimulant of which the other is deprived ; but they do not entitle us to conclude that the persistence of their contractility is the same when placed un- der similar circumstances. We have every reason for believing that the right auricle is the part of the heart which last loses its contracti- lity. Indeed Haller himself confesses, that if any part of the heart remains longer contractile than another, it is the right auricle. Nysten,f who performed a number of experiments upon the comparative persistence of the irritability in the different contractile parts of the body in the human species, after decapitation by the guillotine, and when the heart was conse- quently emptied of its blood, obtained the fol- lowing results upon the order in which the dif- ferent parts of the heart lose their contractility : — 1st, the left ventricle, the contractility of which is annihilated much more quickly than that of the other organs ; 2d, the right ventri- cle, the movements of which generally continue more than an hour after death ; 3d, the two auricles, the right being of all the parts of the heart that which preserves for the longest time its contractile power. The stimulant used in these experiments was galvanism. The greater persistence of the con- tractility in the right auricle over the other parts of the heart has been observed by other experi- menters, after it had been cut from the body, and consequently without any contained blood. The particular part of the auricle which last loses its contractility varies in different cases. Sometimes the appendix is found contracting when the rest of the auricle is quiescent; at other times, and perhaps more frequently, those parts of the auricle around the entrance of the venaj cava? retain their contractility longest. * Sur le mouvement du sang, p. 172. Similar experiments were performed by Walther with the same results : Experimenta de vivis animalibus, p. 11, as quoted by Burdach. t Rechcrches de Physiologie, &c. p. 321. 608 HEART. Harvey and some of the older anatomists ob- served the movements of the venae cava to continue in some of the lower animals after the auricles had ceased to move. The apex of the ventricles frequently remains longer contractile than the rest of the ventricle. Haller suggested that this might depend on the remaining blood gravitating to the apex, and there acting as a stimulant. Duration of contract Mitt/ after death. — In the cold-blooded animals the heart may be made to contract fourteen, twenty, thirty-four hours, or even longer after death. In warm- blooded animals the heart remains contractile for a much shorter period after death than in cold-blooded animals. Haller found the heart contractile in a warm-blooded animal in one case four hours after death, and in another seven hours. He sometimes observed it to cease before the vermicular motion of the intes- tines. Wepfer found it irritable in a dog six hours after death. Nysten, who attended par- ticularly to this subject, found in one of his experiments on the human subject, that the ventricles refused to contract upon the applica- tion of galvanism one hour after decapitation, while the auricles continued contractile for seven hours five minutes after death.* In ano- ther case the right auricle was still contractile eight hours after death ;f and in a subsequent case which he relates, it remained contractile in the neighbourhood of the entrance of the supe- rior cava sixteen hours and a half after death. J In the Mammifera, Nysten found that the left ventricle often refused to contract thirty minutes after death ; that the right ventricle retained its contractility two hours, and sometimes longer, while the right auricle was not quiescent upon the application of the galvanism until eight hours after death. He found it to vary in birds according to the degree of muscular activity which they enjoyed during life. In those of high flight, and which exercise great muscular contractility during life, and have a rapid circulation, as the sparrow- hawk, the irritability of the heart and other muscles becomes much more speedily exhaust- ed than in those the movements of which are comparatively slow and feeble, as in most domes- tic fowls.§ Nysten supposes that the explana- tion of the greater persistence of contractility of the right ventricle over the left lies in the cir- cumstance that the left acts with greater vigour during life, thus referring it to the important general law which he has established by his experiments upon the comparative excitability of the muscular tissue in the various classes of animals, that the duration of the contractility after death is in the inverse ratio of the muscu- lar energy developed during life.|| Before we » Op. cit. p. 316. f Page 318. i In these experiments all the other parts of the body lost their contractility before the right auricle. § Op. cit. p. 349. || Dr. Marshall Hall (Phil. Trans. 1832) has more lately laid it down as a general law that the irritability of the heart and other muscles is in the inverse ratio of the oxygen consumed in respiration. could admit this explanation, it would be ne- cessary to show, what we believe it will be found impossible to do, that the left ventricle, apart from its greater quantity of muscular fibre, exerts greater strength or exhibits more ener- getic contractions during life than the right ventricle. In young animals, immediately after birth, the contractility of the heart continues longer after death than in the adult animal. We would expect this to be most apparent in those which are born with their eyes shut, as puppies and kittens, and in those birds which are hatched without feathers, since these ani- mals at that period of life approach in their physiological conditions to the cold-blooded animals. There is a curious circumstance stated by Mangili, and confirmed by Dr. Mar- shall Hall, connected with the hybernation of animals, that if those mammalia which hyber- nate are killed while under a state of lethargy, the heart and other muscles remain contractile for a longer period than when they are killed in a state of activity, thus resembling, when under the influence of this lethargy, in this as in many other respects, the physiological con- dition of the cold-blooded animals. The con- tractions of the heart may frequently be renewed by the application of warmth after they have apparently ceased. I have repeatedly observed the fact which has been stated by Haller and Nysten, that when any of the cavities of the heart become congested with blood, their con- tractility becomes arrested, and, in their opi- nion, extinguished.* I have also found that unloading the right side of the heart soon after the congestion has taken place, which can be done in many cases by opening the external jugular vein, acts as a valuable adjuvant under certain circumstances in renewing the heart's action. These it would be out of place to dis- cuss here ; but I may state that it appears to me to be principally useful in certain cases of poisoning, in asphyxia, and after the accidental entrance of air into the veins. Since the intro- duction of a considerable quantity of air into the veins produces death by mechanically ar- resting the movements of the right side of the heart, we believe that circumstances may occur in which the surgeon may be justified in intro- ducing a tube into one of the large veins pass- ing into the upper part of the chest, and suck- Various experimenters distinctly show that as we descend in the scale of animals the quantity of oxy- gen consumed diminishes, and that Birds consume more than Mammalia. Dr. Edwards has also shown that the young of the Mammalia deteriorate the atmospheric air less rapidly than the adult ani- mals ; and the experiments of Mangili and Prinella prove that hybernating animals, when in a state of lethargy, consume exceedingly little oxygen, so that there is evidently some relation between irri- tability and the quantity of oxygen consumed in re- spiration ; but for the proof that the irritability is exactly in the inverse ratio of the respiration, we must wait for Dr. Marshall Halt's promised experi- ments. * Haller supposed that this was effected, as must be if allowed to continue for any length of time, by the too great distension of the muscular fibres, in the same manner as distension of the bladder produces paralysis of its fibres. HEART. C09 ing the frothy blood from the right side of the heart. It is also necessary to remember this circumstance in experimenting upon the length of time during which the heart remains con- tractile after death, as the division or non-divi- sion of the large veins at the root of the neck in laying open the thorax may considerably modify the results.* For the probable force exerted by the heart, the share which the heart has in carrying on the circulation, and the probable quantity of blood expelled at each contraction, see the article Circulation. Frequency of the heart's action. — The fre- quency of the heart's action is considerably modified by age, condition of the other functions of the body at the time, by mental emotions, and by the original constitution of the individual. Its movements are influenced by very slight muscular exertion, and the extent of this appears to vary at different times of the day. In the foetus its movements are rapid, being about 140 in the minute. At birth it is from 130 to 140; at one year 115 to 130; second year 100 to 115; third 90 to 100; seventh 85 to 90; fourteenth 80 to 85; middle age 70 to 75; in very old age 50 to (35. The heart's action generallysympathises powerfully with the other organs of the body, and this has always been regarded as a most important and necessary guide in the detection and cure of diseases. It becomes strong and rapid in some cases of inflammation, while in others it becomes rapid and feeble. It becomes quicker after eating and slower during sleep. It is much increased in frequency during bodily exertion. In cases of great general debility it becomes very quick and feeble. It becomes more rapid and weaker during inspiration, slower and stronger during expiration. It is an important fact that when the con- tractility of the heart is much enfeebled by extensive injuries of the central organs of the nervous system or of the other parts of the body, (as when a limb is extensively crushed,) its contractions are not only much weaker, but are also greatly increased in frequency. It is also worthy of remark that such injuries do not pro- duce convulsive movements in this organ. The effect which severe injuries and certain inflam- matory affections have in greatly debilitating or even destroying the contractility of the heart is a fact of great practical importance, as it not only explains the cause of the most alarming symptoms in such cases, but also points out the most appropriate remedies to avoid the chief tendency to death. To this cause, for example, we are to attribute the rapid and feeble pulse, in concussion of the brain, in extensive mecha- nical injuries, the shock after operations, exten- * Edinburgh Medical and Surgical Journal, 1836. When I performed these experiments, I was not aware that I had been anticipated to a certain ex- tent by Mr. Coleman. (Wilson on the Blood, &c. p. 131.) It is very possible that the sinuses upon the inferior cava and hepatic veins in the seal may, besides answering other purposes, have the effect of preventing this mechanical distension of the right side of the heart. VOL. II. sive burns, peritonitis, &c. It is very fortunate that the contractions of the heart become more frequent when its contractility becomes en- feebled. If the heart under these circumstances had required, as we would a priori expect, the presence of a greater quantity of blood to stimulate it to contraction, instead of a smaller quantity, as is actually the case, what would have been the consequence ? It is evident that since the resistance, under ordinary cir- cumstances, which the heart has to overcome in contracting, is, according to a well-known hy- drostatic law, in proportion to the extent of the area of the inner surface of the cavities of the heart at the commencement of their contraction, (each square inch of surface, according to the experiments of Hales, having a pressure upon it nearly equal to four pounds,) the more fre- quent contractions, where there is a smaller quantity of blood present in the heart at the commencement of each contraction, will not demand the same degree of muscular force for their performance, as if these had been less frequent. If, when the contractility of the heart became debilitated, the presence of a greater quantity of blood than usual in its interior had been necessary to stimulate it to contraction, and if the area of the inner surface of the cavities of the heart be in proportion to the quantity of blood contained there, it is apparent that the movements of the heart would have been much more rapidly and frequently arrested when its contractility became enfeebled, than they are under the actual arrangement. The influence of mental emotions upon the movements of the heart requires no illustration, for this is so universally experienced that in common language the heart is considered to be the seat of the affections and passions, and this has had a powerful influence upon the phrase- ology of all languages. In sanguine temperaments the heart gene- rally contracts morefrequently than in phlegmatic temperaments. In women it is also generally a little quicker than in men. It varies very much in different classes of animals. Burdach* has given the following table col- lected from numerous sources, as an approxi- mative valuation of the frequency of the heart's action in various animals. Number of pulsations in a minute.^ In the Shark 7 Mussel 15 Carp 20 Eel 24 Snake 34 Horse 36 Caterpillar 36 Bullock 38 • Physiologie, vol. iv. p. 251. t We cannot consider the number of pulsations of the heart in a minute given in the above table as by any means quite satisfactory. The number of pulsations in the ox and horse is given on the authority of Vetcl in Froriep, Notizen, t. xxiv. p. 112. Other observers state the number of pulsa- tions in a minute at from 38 to 52 in the horse, and from 64 to 70 in the ox. 2 S CIO HEART. Ass '.. 50 Crab 50 Butterfly 60 Goat 74 Sheep 75 Hedgehog 75 Frog 77 Marmot , 90 Locust 90 Ape 9o Dormouse 105 Cat 110 Duck 110 Rabbit 120 Menoculus Caster 120 Pigeon 130 Guinea-pig 140 Hen 140 Bremus terrestris 140 Heron 200 Menoculus pulex 200 For the effects of the respiration upon the contractions of the heart, and the influence of the circulation of dark blood upon its irrita- bility, see Asphyxia. The cause of the motion of the heart. — The motion of the heart, and the constancy and regularity of its movements, are circumstances so remarkable that they could not fail early to excite a deep interest among medical philo- sophers when they had once turned their attention to the explanation of vital phenomena. When we contemplate the heart commencing its movements at an early period of foetal existence, and never resting from its apparently unceasing toil until the latest moments of life, and when we remember the uniform and regu- lar manner in which all its actions are accom- plished—all conspiring for the proper per- formance of the deeply important functions assigned to it, we are at first impressed with the idea that it is regulated by laws different from similar textures of the body, and altogether peculiar to itself. It must have been under the influence of similar impressions that the older medical philosophers approached this subject, and it is in this manner only that we can account for many of the strange specula- tions on the heart's action which they have left recorded. We find one sect attempting to explain it by a peculiar innate fire. Sylvius, the head of the chemical sect, had recourse for its explanation to an effervescence excited by the intermixture of the old and alkaline blood with the acid chyle and acid pancreatic lymph.* Descartes supposed that a constant succession of explosions occurred in the heart from steam generated there, which propelled the blood through the body. Stahl got at once out of the difficulty by affirming that the heart was more particu- larly under the guidance of the anima or soul. But we cannot here dwell longer on these ob- * In the same manner Borelli says, " Constat ex dietis immediatam causam motivam cordis esse ebullitionem fermativam tartarei succi sanguinei excitatam a commistione succi spirituosi a nervis instillati." Be Motu Animalium, p. 97. solete and to us in the present time almost incredible opinions, and the only use to which they are now applicable is to serve as beacons to keep us, in all our inquiries into the pheno- mena of living bodies, within the strict path of facts and observation, and to forcibly impress upon us into what strange and fatal errors even the brightest intellects may fall, when they leave the inductive method of investigation, and wander into the alluring but dangerous regions of hypothesis. And the effects of these errors are only the more to be dreaded as they are often clothed in the most seductive in- genuity. It ought also still more forcibly to inculcate upon us the important truth, which, though generally in our mouths, is not unfre- quently forgotten in practice, — that as the material world and all which it contains have been placed by the Author of Nature under arbitrary and fixed laws, it is impossible to ex- tend our knowledge of these by theorizing in the closet, and that this can only be effected by the patient interrogation of Nature herself. It was not until the time of Senac and Haller that accurate notions began to be enter- tained on the nature of the heart's action. The cause of the movements of the heart is distinctly referable to the same laws which regulate muscular contractility in other parts of the body, only modified to adapt it for the per- formance of its appropriate functions. Like all the other muscles it is endowed with irrita- bility, which enables it to contract upon the application of a stimulus. The ordinary and natural stimulus of the heart is the blood, which is constantly flowing into its cavities. The greater irritability of the inner surface over the outer is evidently connected with the manner in which the stimulus is habitually applied. When the blood is forced on more rapidly towards the heart, as in exercise, its con- tractions become proportionally more frequent; and when the current moves on more slowly, as in a state of rest, its frequency becomes pro- portionally diminished. If the contractions of the heart were not dependent upon the blood, and their number regulated by the quantity flowing into its cavities, very seiious and in- evitably fatal disturbances in the circulation would soon take place. As the heart continues to contract often for a very considerable time after the venaa cavae have been tied, and after the blood has ceased to pass through its cavities, or after it has been removed from the body, this has been supposed by some to indicate that there is something in the heart's structure or in its vital properties which enables its movements to proceed inde- pendent of all other circumstances. But in all these cases a stimulus has been applied in some form or other to the heart. If the heart has been allowed to remain in its place, though the circulation of the blood may have come to a stand, part of it may yet remain in the different cavities of the organ ; or if the pericardium has been opened, the impression of the external atmosphere may act as a stimulus. The expe- riments of Walther and Haller formerly men- tioned upon the comparative irritability of the HEART. 611 two sides of the heart, and the different results obtained when the one side of the heart was emptied of blood, and when it was retained in the other, are sufficient to shew the effect which the presence of blood in the cavities of this organ has upon the continuance of its action after the circulation has ceased. If the heart has been removed from the body and emptied of its blood, it must naturally follow that its different cavities will be tilled with atmospheric air ; and it has been well ascertained that this acts as a very powerful stimulant upon the inner surface of the heart.* Every circumstance connected with these experiments is in exact conformity with the opinion that the movements of the heart are only called into action by the application of a stimulant. Thus, when the irritability of the heart becomes more languid, and when the blood or the atmospheric air in its cavities becomes insufficient to raise it to contraction, strong and energetic movements may still generally be excited by having recourse to a more powerful stimulant, such as the prick of a scalpel or the application of galvanism. Since the heart is highly en- dowed with irritability, various other mild fluids besides the blood are capable of exciting it to contraction. As every organ, however, has its irritability adapted for the function which it is destined to perform, so we find that the heart, the central organ of the circulation, is most fitly called into action by the blood, its appro- priate and natural stimulant. In examining the nature of the irritability of the heart, and contrasting it with that of the voluntary muscles, we must not compare its contractions with those excited by volition in the muscles of voluntary motion, for these last are evidently modified by the nervous influence for an obvious purpose ; but let us observe both when placed under similar circumstances, and irritated by the application of the same stimu- lant applied to the muscles themselves, and we will find that they only differ in this, — that in the voluntary muscles each successive appli- cation of the stimulant is generally followed by a single contraction, while in the heart it is followed, except when the contractility is much impaired, by several consecutive con- tractions alternated with relaxations. This ten- dency to successive contractions is also observed, though not to the same extent, in the muscular coat of the intestines. We must admit, however, that the contrac- tions of the heart proceed under circumstances where it is difficult to point out the presence of any sufficient stimulus, and where, to account for their continuance, we are almost obliged to have recourse to the supposition, that there is some innate moving power in the heart itself. It has been stated, for example, that the move- * Peyer, Brunner, and Hallcr have seen the con- tractions of the heart renewed by blowing air into the cava ascendens. Wepfer and Steno produced the same effect by inflation of the thoracic duct. Ennian states that he once observed the renewal of the heart's action in the human subject by blowing air into the thoracic duct. Vide Senac, torn, i. p. 326. ments of the heart will proceed under the ex- hausted receiver of an air-pump. I have repeatedly placed under the bell-glass of an air-pump the heart of a frog when removed from the body and emptied of its blood, and I could never satisfy myself that the frequency or strength of its contractions was at all affected by the withdrawal or renewal of the air ; and though it might be urged that the air is only rarefied, not entirely removed, in the best ex- hausted receiver of an air-pump, and that con- sequently in such experiments a stimulant still existed in the presence of the rarefied air, yet I would not consider this explanation of the continuance of its contractions by any means satisfactory. In these experiments there is ano- ther source of stimulation present which ought to be taken into account, for, as I shall after- wards shew, the slightest movement of the heart, such as that caused by its contraction, upon the surface upon which it is placed when removed from the body, is sufficient, from the great irritability of the organ, to act as a stimu- lant upon it. If these external stimuli appear to be insufficient to account for the persistence of the contractions of the heart under the cir- cumstances we have mentioned, we may have recourse to another explanation drawn from the mechanical structure of the organ ; for it is possible, as has been suggested by Dr. Alison, that from the peculiarly convoluted arrangement of the fibres, the outer may, during the con- traction of the organ, pinch or stimulate the inner, and so cause this tendency to repeated contractions from one application of a stimu- lant. We do not, however, consider that we have succeeded perfectly in accounting for the continuance of the contractions of the heart under all circumstances, but we are unwilling to admit the existence of any peculiar innate and unknown agency in the production of any phenomenon, until it is satisfactorily established that it cannot be accounted for on the known laws which regulate similar phenomena in the same texture in other parts of the body. And it must also be remembered that these move- ments of the heart have only been observed when its contractility was still comparatively vigorous, and where sources of stimulation were still present. We ought, besides, to be the more cautious in admitting the existence of this innate moving power, since it is in opposition to a well-known law in the animal economy, — that though the various tissues of an organized body are endowed with certain vital properties, yet the application of certain external and internal stimuli is necessary to produce their manifestations of activity. In fact it is from the action and reaction of these tissues and excitants upon each other, that the phenomena of life result.* * The remarks which we have made above, illustrating the great length of time which the heart will continue to contract after being removed from the body, and when all communication between the nerves ramified in its substance and the sympathetic ganglia and the central organs of the nervous sys- tem have been cut oft, when taken along with the equally well ascertained fact, that its contractions 2 S 2 612 HEART. Upon what does this irritability of the heart depend ? — This has been one of the most keenly agitated questions in physiology, as a great part of the experiments, and much of the reasoning upon the nature of muscular irritability, have been furnished by this organ. As, however, the general doctrines entertained on this subject have already been fully discussed under the article Contractility, we shall here confine ourselves to a few of the leading facts connected with it which have a special reference to the heart. The two principal questions on this point since the time of Haller have been, whe- ther does it depend upon nervous influence ? or is it a property of the muscular fibre itself independent of the nerves ? • We have seen that the nerves distributed upon the heart are the par vagum and sympa- thetic. Numerous experimenters have removed portions of the par. vagum on both sides of the neck without the slightest diminution of the strength of the contractions of the heart. These experiments we have frequently performed with the same results. There can now be no doubt that the sudden death which occasionally fol- lows this operation is not to be attributed to the cessation of the heart's action, as some of the older experimenters believed, but, as Legallois has shewn, it depends upon an arrestment of the movements of the muscles attached to the arytenoid cartilages. Portions of the sympa- thetic have also been destroyed in the middle of the neck without any effect upon the con- traction of the heart, except what could be sufficiently accounted for by the pain of the incisions and the terror of the animal. A por- tion of both of the sympathetic and pneumo- gastric nerves may be removed in the neck with the same results; in fact we cannot, in the dog and most quadrupeds, cut the par vagum in the middle of the neck without also dividing the sympathetic. Magendie affirms that all the sympathetic ganglia of the neck, along with the first dorsal, may be removed without any sensible derangement of the parts to which their nerves are distributed. Brachet* supposes that the reason why the excision of the sympathetic ganglia in the neck does not always arrest the heart's action, is because there is another source of nervous influence for the cardiac nerves placed below this in the cardiac plexus or ganglion. He accordingly put this opinion to the test of experiment, and he as- sures us that the total destruction of the cardiac plexus was followed by the sudden and perma- nent arrestment of the heart's action. Now may be readily increased or renewed under those circumstances, by mild excitants applied to its inner surface, are completely opposed to the supposition that the heart is called into contraction in a manner similar to those sympathetic movements more lately described under the term excito-motary. Though this mode of explanation may be considered quite legitimate when applied to those sympathetic move- ments which do not require the intervention of the brain for their performance, such as deglutition, respiration, &c, it is certainly pushing the doctrine far beyond its proper limits to apply it to the explanation of the movements of the heart. * Du systeme nerveux ganglionairc.. p. 120. when we consider the nature of such an ex- periment as this, with the chest of the animal laid open, the respiration arrested, and the heart exposed during the time the experimenter is searching and tearing for the plexus placed deep behind the aorta and pulmonary artery, and which would require a considerable time to display even in the dead body when unem- barrassed by the movements of the heart, we must be more astonished that the action of the heart had not completely ceased before the ex- periment was finished, than that it should have continued so long. Besides, even allowing that this experiment could be relied upon, we have sufficient evidence, from the facts stated above, to entitle us to conclude that the heart is not dependent for its movement upon any influence constantly transmitted along its nerves from the central organs of the nervous system, — the brain and spinal marrow. Brachet is himself obliged to admit, from other experiments which he performed, that the division of the sympa- thetic at the lower part of the neck is not suffi- cient to arrest the heart's action, so that this experiment is intended to shew that its irrita- bility depends upon the ganglia of the sympa- thetic itself. The independence of the irrita- bility of the heart upon the brain and spinal marrow can be very satisfactorily proved in another manner. The occurrence of acephalous monsters,* and the experiments of Wilson Philip,! CliftjJ and Brachet§ demonstrate that the brain or spinal marrow may be naturally wanting ; that one or both of them may be removed entirely, or destroyed in small portions at a time, without arresting the heart's action. We may here observe that the experiments of Legallois, || Wilson Philip, Wedemeyer,1f Bra- chet, and many others, in which the action of the heart was arrested by crushing large portions of the brain or spinal marrow, though they do not prove the dependence of the irritability of the heart upon the brain and spinal cord, at least shew, what the effects of mental emotions upon the movements of the heart had already pointed out, that it can be influenced to a great and most important extent through these organs. The advocates for the dependence of the irrita- bility of the heart upon the nerves appear to have pretty generally abandoned the opinion that this is derived from the central organs of the nervous system, and now maintain the doctrine, which was more prominently deve- loped by Bichat, that this is derived from the sympathetic, the ganglia of which, according to him, are independent sources of nervous influence. From the manner in which the sympathetic is distributed upon the heart, it is * The heart is generally though not always ab- sent in acephalous monsters. f Experimental Inquiry into the vital functions. X Phil. Trans. 1815. § Systeme nerveux ganglionaire. || Legallois performed these experiments on the spinal cord alone, and supposed he had proved that the movements of the heart were dependent upon that portion of the nervous system. K Physiol. Untersuchungen iiber das Nerven- systcm, &c. p. 235. HEART. 613 perfectly impossible to insulate that organ from the nerve and experiment upon it ; but we think we are justified in concluding from ob- servations and experiments derived from other sources, that in all probability the contractility of the heart depends upon a property possessed by the muscular fibre itself without any neces- sary intervention of its nerves. The possibility of exciting or increasing the action of the heart by stimuli applied to its nerves has been mixed up with this question. Though it must be admitted that mechanical and chemical stimu- lants applied to a considerable surface of the central organs of the nervous system quicken the heart's action, yet experimenters have gene- rally acknowledged that these stimulants applied to the nerves of the heart produce no effect upon its movements. Burdach,* however, maintains that he lias quickened the heart of a rabbit deprived of sensation by applying caustic potass to the trunk of the sympathetic, or its in- ferior cervical ganglion. That the heart can be excited to contraction by the application of galvanism has had many supporters, and many celebrated names are arranged both on the affirmative and negative sides of the question. That the movements of the heart may be in- creased or renewed by the application of gal- vanism as the experiment is usually performed, there can be no reasonable doubt ; for if one wire is placed upon the nerve and the other upon the heart, the moist nerve will act as a conductor to the electricity, and the effect pro- duced will be the same as if the stimulant had been applied to the substance of the heart itself. Nysten admits that movements of the heart were excited by the galvanism when one of the wires was applied to one of the large arteries from which all the visible filaments of the nerves had been dissected off. Dr. C. Holland,! in a number of experiments, satisfied himself that the tissues of the body conduct galvanism with so much facility, that the heart's action could readily be excited, when one wire was placed upon the heart and the other in the nose, mouth, and even among the moist food in the stomach. I have performed similar experiments with the same results. Humboldt and Brachet assert that they have quickened the movements of the heart by applying both wires to one of the cardiac nerves. If these and the experi- ments of Burdach could be relied upon, they would be sufficient to prove that the heart could be occasionally stimulated through the cardiac nerves, but the negative experiments on the other side are so numerous, and the sources of fallacy in judging in this manner of the relative quickness of the heart's action between one time and another so obvious, that we must be allowed to distrust them unless they should be confirmed by other accurate observers. Constancy of the heart's action. — The con- stancy of the heart's action is more apparent than real. After each contraction a state of relaxation follows. The relative duration of * Traite de Physiologic, torn. vii. p. 74, traduit par Join dan. t Experimental Inquiry, &t. p. 275. the contraction of the auricles and ventricles, according to Laennec, appears to be as fol- lows : — a third at most, or a fourth or a little less by the systole of the auricles ; a fourth or a little less by the state of quiescence ; and the half or nearly so by the systole of the ventricles. From this he calculates that the ventricles, when the heart is acting with its usual frequency, rest twelve hours out of the twenty-four, and that in those individuals in whom the pulse is naturally below 50, it must be in a state of relaxation sixteen hours out of the twenty-four.* Now this is a degree of contraction of which many muscles of the body are probably suscep- tible, such as the muscles which support the trunk when we sit or walk, and which some, as the diaphragm and intercostals, generally perform. Regularity of the heart's movements. — The regularity of the heart's movements, so essential to the welfare of the animal, has appeared, even to many modern physiologists, to be inti- mately connected with some peculiarity in its structure. We are inclined, however, to agree with Haller, that this is perfectly explicable on the known laws of muscular contractility in other parts of the body. The regularity of the heart's action was another fertile subject of hypothesis to the older physiologists ; and even in the present day we find the term " organic instinct'' employpd to designate it. The contractions of the heart take place in the order in which the blood flows into its different cavities; and if the blood be the habi- tual stimulant upon which its movements depend, this is exactly what we would expect. f The blood forced in greater quantity into the auricles by the contraction of the termination of the cava; and pulmonary veins, stimulates the auricles to contract and propel an additional quantity into the ventricles ; and this, acting as a stimulant upon the ventricles, excites them to contract and drive the blood into the arteries, when the same series of phenomena is renewed and repeated in the same succession. The continuance of the heart's action after the circulation has ceased, we have already attempted to explain ; and if these contractions depend upon the presence of a stimulus, they must evidently be in the same order as in the natural state of the organ, as these have not been interrupted. The continuance of the re- gular order of the contractions of the heart after its removal from the body can in general, we think, be satisfactorily accounted for by the substitution of a new stimulant for that of the blood ; the cavities are then occu- pied with air instead of blood, and each * We have "not here given Laennec's calculations of the relative duration of the contraction and relaxation of the auricles, as they must be founded on false data — on the supposition that the second sound of the heart marked the duration of the con- traction of the auricles. t This was also the doctrine maintained by Se- nac, op. cit. torn. i. p. 325. Senac, however, was opposed to the doctrine of Haller, that the contrac- tility of the heart was a property inherent in the muscular fibre, and independent of the nerves, Tom. i. p. 451. 614 HEART. contraction of the auricle must force an ad- ditional quantity into the ventricle, and this, though small in quantity, may be quite suffi- cient to excite the ventricles to contraction, when the irritability is not too much impaired.* It is only in this manner, taken along with the greater irritability of the internal surface over the external, that we can explain the observa- tion made by Dr. Knox in the course of his experiments upon the irritability of the heart in fishes, where, when the irritability was nearly exhausted, contractions excited in the auricle were sometimes followed by contractions of the ventricle, when irritation of the outer surface of the ventricle itself produced no effect.f Cer- tainly, under ordinary circumstances, this regu- larity of the heart, so necessary for the proper performance of its functions, is a marked fea- ture in its action ; but that it is not either ne- cessarily connected with its structure or vital properties, but depends solely on the manner in which its stimulant, the blood, is applied, is proved by various facts. 1st. The movements of the auricles and ventricles generally cease at different times after death ; and though the auricles much more frequently continue to con- tract after the ventricles, yet several accurate experimenters have observed the left auricle become quiescent before its corresponding ventricle.]; 2dly. When the movements of the ventricle have ceased, while the auricles continue to contract, the ventricle may generally be excited to vigorous contractions by the ap- plication of a powerful stimulus. 3dly. When the irritability of the heart becomes somewhat languid, two, three, or sometimes six or seven contractions of the auricle may take place be- fore the ventricles are roused to contraction ; the evident deduction from which is, that the * When the heart has ceased to contract, it may frequently be called into pretty vigorous action by opening one of the large veins, and blowing some air into its cavities. t I have repeatedly attempted to ascertain if the circumstances here described as sometimes occurring in the cold-blooded animals could be observed in the warm-blooded animals, but without success. In one experiment upon the heart of a rabbit, after all the movements of the ventricles had ceased, but where they could still be readily excited by the application of a stimulant, we were convinced that contraction of the auricle, when excited by stimu- lation applied to itself alone, was sometimes fol- lowed by contaction of the ventricle even after the ventricle had been slit open. But in subsequent experiments upon dogs, we ascertained a source of fallacy which we had overlooked in the other expe- riment, for we found that a slight movement of the heart on the surface upon which it rests, such as that caused by a very gentle pull at the large arteries, and not exceeding the effects produced by the contraction of the auricle, was, in some of these cases, sufficient to excite contractions of the ventricles. } In one experiment upon a cat, I distinctly ob- served the right ventricle occasionally pulsate twice for each pulsation of the auricle. In another experiment, 1 distinctly observed the contractions of the ventricles precede those of the auricles, when the contractility of the heart had become en- feebled. In this case, the pause in the heart's action occurred after the contraction of the auri- cles. contractions of the ventricles do not neces- sarily follow those of the auricles, unless the contractions of the auricles occasion the application of a stimulant to the inner sur- face of the ventricles sufficient to excite Ihem to contraction. 4thly. The movements of the ventricles and auricles will go on in the same manner, though detached from each other by the knife. 5thly. If we were allowed to argue from final causes in negative cases, we could easily shew that a peculiar endow- ment, such as we are contending against, would not be of the slightest advantage in se- curing the regularity and constancy of the heart's movements. It appears, then, quite un- philosophical to call in the agency of some un- known and indefinite principle for the produc- tion of these periodic movements, as they have been called, of the different chambers of the heart, when they can be satisfactorily referred to the laws which regulate muscular contracti- lity in other parts of the body. We have here a beautiful example of the manner in which nature produces adaptation of means to an end, not by the creation of new properties, which we, in our ignorance, sometimes erroneously attribute to her, but by the employment of those already in use in the performance of other functions, only modified to accommodate them to the circumstances under which they are placed. Sounds of the. heart. — On applying the ear over the region of the heart, two distinct sounds are heard accompanying its contraction. Though the existence of such sounds seems to have been known to Harvey,* who compares them to the noise made by the passage of fluids along the oesophagus of a horse when drinking, yet, as is well known, it is to Laennec that we owe the first accurate description of the charac- ter of these sounds, the order of their succes- sion, and the manner in which they may here- after be made available for the important pur- poses of the diagnosis of the diseases of the heart. The first of these sounds is dull and pro- longed ; the second, which follows closely upon the first, is sharp and quick, and is likened by Laennec to the flapping of a valve, or the lap- ping of a dog. After the second sound a pause ensues, at the end of which the sounds are again heard. These three — the first sound, the second sound, and the pause — occur in the same uniform order, and when included along with the movements of the heart, to which they owe their origin, have received the term rhythm of the heart. As the dull prolonged sound is synchronous with the impulse of the heart, and consequently with the contraction of its ventri- cles, Laennec attributed this sound to the con- traction of the ventricles. The second sound, which is synchronous with the diastole of the ventricles, he supposed must depend upon the systole of the auricles ; and to this he was naturally led by the supposition that their con- traction must also produce some sound. From the weight of Laennec's authority, this opinion * Op. cit. cap. v. HEART. 615 seems to have been almost implicitly adopted un- til the appearance of a paper by the late Professor Turner, in 1829. Professor Turner there re- called to the attention of medical men the observations of Harvey, Lancisi, Senac, and Haller, upon the order of succession in which the cavities of the heart contract, which appear to have been forgotten amidst admiration at the brilliancy of Laennec's progress. He also pointed out from their experiments that if the second sound was dependent upon the con- traction of the auricles, it ought to precede instead of following the first sound, and that the pause ought to occur after the first sound, and not after the second. He also adduced, in farther proof of Laennec's error, observations drawn from the effects of disease, when, from some impediment to the passage of the blood from the right auricle into the ventricle, a dis- tinct regurgitation takes place into the large veins at the root of the neck, and showed that in these cases the regurgitation marking the contraction of the auricles occurs without any accompanying sound ; that immediately after- wards the impulse is felt attended by the first sound, and that the second sound takes place during the diastole of the ventricles and the passive condition of the auricles. He suggested that the second sound might be accounted for by the falling back of the heart into the pericardium during its diastole, to which "the elasticity of the ventricles at the commencement of the diastole, attracting the fluid by suction from their corresponding auri- cles, may perhaps contribute." Soon after the appearance of Mr. Turner's paper, Laennec's explanation of the cause of the second sound appears to have been pretty generally aban- doned ; and numerous attempts, both in this country and in France, have since that time been made to solve this difficulty. Some of these explanations appear to be mere guesses, occasionally at total variance with the anato- mical structure of the organ, and at times pre- senting even as wide a departure from its nor- mal action as that given by Laennec himself. Others, again, have entered upon an experi- mental investigation of the subject with en- lightened views of its anatomy and physiology, have furnished us with much additional infor- mation, and lead us to indulge in the pleasing prospect that in a short time the matter will be completely set at rest. The result of the experiments of Hope and Williams, attested as they have been by various gentlemen well qualified to judge of their accuracy, — also those of Mr.Carlisle, Magendie, Bouillaud, and the Dublin Committee, have satisfactorily determined that the account of the order of the contractions of the heart, and their isochronism to the sounds as stated by Mr. Turner, are perfectly correct. As, how- ever, so many different circumstances attend each movement of the heart, any one of which may be capable of producing these sounds, it became a much more difficult matter, and one requiring great perseverance and accuracy of investigation, to determine upon what particular one or more of these, each sound depends. For accompanying, and synchronous wtth the first sound, we have the contraction of the ven- tricles, the collision of the different currents of blood contained there thus set in motion, the approximating of the auriculo-ventricular valves, the impulse of the heart against the chest, and the propulsion of the blood along the large arteries; while attending the second sound, we have the diastole of the ventricles, and the rush of a certain quantity of blood from the auricles into the ventricles, the sudden separation of the auriculo-ventricular valves towards the walls of the ventricles, and the regurgitation of part of the blood in the arteries upon the semi- lunar valves, throwing them inwards towards the axes of the vessels ; so we will find that each of these in its turn has been thought ca- pable of producing the sound which it accompa- nies, and still has, or until lately had, its advocates and supporters. As the subject is one surrounded with numerous and unusual difficulties, and is of comparatively recent investigation, it has fol- lowed, as was to be anticipated, that as new facts and observations are collected, many of the opinions first promulgated on this question have required to be modified or changed; and the scientific candour displayed by several of these authors in renouncing former published opinions is deserving of the highest praise. Several of the explanations of the cause of the sounds of the heart proceed, however, upon the supposition that the relation of these sounds to the movements of the organ is different from what has been here represented. We shall merely state these without alluding to the arguments adduced in support of them, as we believe that they are founded upon inaccurate observation. Sir D. Barry believed that the first sound was synchronous with the diastole of the auricles, and the second sound with the diastole of the ventricles. Mr. Pigeaux, Dr. Corrigan also until lately, Dr. Stokes, Mr. Hart, and Mr. Beau, have maintained that the first sound is synchronous with the diastole, and not with the systole of the ventricles. Ac- cording to Mr. Pigeaux, when the auricles contract they project the blood against the walls of the ventricle, and a dull sound (first sound) is produced ; on the other hand, whilst the ventricles contract, they project the blood against the thin walls of the great vessels which spring from them, and a clear sound (second sound) is the result. Dr. Corrigan supposed that the first sound was produced by the rush of blood from the auricles into the dilating ventricles, and that the second sound owed its origin to the striking together of the internal surfaces of the ventricles during their contrac- tion, after they had expelled all their blood. Mr. Beau believes with M. Magendie that the first sound arises from the impulse of the heart against the inner surface of the chest, but differs from him in maintaining that this occurs during its diastole, and not during its systole. The second sound he believes to depend upon the dilatation of the auricles. M. Piorry has revived the obsolete and perfectly untenable opinion of Nicholl, that the two ventricles contract at different times, and attributes 616 HEART. the dull sound to the contraction of the left ventricle, and the clear sound to the contraction of the right ventricle. Dr. David Williams, while he believes that the first sound depends upon the rush of blood into the large arteries during the systole of the ventricles, attributes the second sound to the musculi papillares, which he considers as forming part of the val- vular apparatus, causing the valves to strike against the walls of the ventricles. These mus- culi papillares do not, in his opinion, contract during the systole of the ventricles, but imme- diately afterwards, for the purpose of throwing open the auriculo-ventricular valves. In a former part of this article several circum- stances are stated adverse to this opinion. We shall now proceed to the explanation of the cause of these sounds given by those who maintain the views of the rhythm of the heart which we have here adopted, as resting upon the concurrent testimony of numerous accurate observers. These may be divided into those who attribute both sounds to causes intrinsic to the organ, or, in other words, to circumstances occurring within the organ itself, and into those who place them external to the organ, and depending upon extraneous objects. The only supporters of the latter opinion are Magendie and his followers. Magendie maintains that "incontracting,andfor causes long since known, the ventricles throw the apex of the heart against the left lateral part of the thorax, and thus produce the first sound, i. e., the dull sound. In dilating, in a great measure under the influence of the rapid influx of the blood, the heart gives a shock to the anterior paries on the right of the thorax, and thus produces the second sound, the clear sound." In proof of this, he states that on removing the sternum of a swan (an animal selected expressly for the experiment, as it interfered less with the natural action of the heart than in the Mam- malia), he found that the movements of the heart produced no sound, while, on replacing the sternum, and allowing the heart to impinge upon its posterior surface as in the natural state, both sounds were again distinctly heard. He adduces several arguments drawn from the action of the heart both in its healthy and dis- eased state in favour of his opinion ; and he ingeniously attempts to get rid of the objection which must instantly suggest itself, that in many cases, such as frequently occur in hyper- trophy of the organ, the loudness of the sounds is diminished, while the force of the impulse is increased, by arguing that in these cases this increased impulse depends rather upon a heaving of the chest produced by the heart, which from its increased size is brought close to its inner surface, than upon a distinct im- pingement upon it, such as takes place in the healthy state. Dr. Hope, M. Bouillaud, Dr. C. J. B. Williams, and the Dublin and London Heart Cominitees have, however, distinctly heard both sounds of the heart, after that por- tion of the chest against which it impinges had been removed. It may, nevertheless, be objected to these experiments, that as the stethoscope was used in many of them, the impulse of the heart against the extremity may have produced an effect similar to its impulse against the parietes of the thorax. M. Bouillaud, having appa- rently this objection in view, states that the rubbing of the heart during its movements against the extremity of the stethoscope, is easily distinguished from the sounds of the heart; and that he has distinctly heard both sounds, though feebler than through a stetho- scope, as was to be expected when nothing but a cloth was interposed between his naked ear and the surface of the heart. Dr. C.J. B. Williams, in his experiments, heard both sounds when the stethoscope was placed over the origin of the large arteries, and where no external impulse could take place ; and this observation was repeated by the Dublin Committee. The Dublin Committee heard both sounds through the stethoscope, though feebler after the peri- cardium had been injected with tepid water ; and in another experiment they were also heard when the ear was simply approximated to the organ. From all these experiments, I think there can be little doubt that the move- ments of the heart, independent of all extra- neous circumstances, are attended by a double sound. As the impulse of the heart against the chest must produce some sound, as any one may convince himself by making the ex- periment in the dead body, and as this occurs during the systole of the heart, or, in other words, during the first sound, it may increase the intensity of that sound. Dr. R. Spittal,* after relating several experiments in which a sound similar to that of the first sound of the heart was heard by tapping gently with the apex of the heart or the point of the finger against the chest, both when empty and when filled with water, and after pointing out several sources of fallacy which he supposes were not sufficiently guarded against in the experiments which we have adduced above as subversive of this view, and which deserve the attention of future experimenters, comes to the conclusion that " it is highly probable that the percussion of the heart against the thoracic parietes during the contraction of the ventricles assists mate- rally in the production of the first sound." He is also inclined to believe " that the act of the separation of the heart from the thorax after its approach, which was found in his experiment to produce a sharp, short sound, somewhat resembling the ordinary sound, may in certain circumstances be an assistant cause to the second sound. "f Magendie's explanation of the second sound is completely untenable. Among those who maintain that these sounds depend upon causes intrinsic to the heart, the first sound is referred by Rouanet, Billing, Bryan, and Bouillaud to the rapid approxima- tion of the auriculo-ventricular valves during the systole of the ventricles, to which Bouillaud * Edin. Med. and Surg. Journal, July 1836. t Though Dr. Spittal is inclined to believe that the impulse of the heart against the chest has con- siderable share in the production of the first sound, he does not concur with Majendie in the explana- tion of the second sound. HEART. 617 adds tho sudden separation of the semilunar valves when the blood is forced into the large arteries ; by Mr. Carlisle to the rushing of the blood along the inner surface of the large arteries during the systole of the ventricles.* Dr. Hope, in the appendix to the second edition of his work, describes it as consisting, 1st, possibly of a degree of valvular sound; 2d, of a loud smart sound produced by the abstract act of a sudden jerking extension of the muscular walls, in the same manner that such a sound is produced by similar extension of the leather of a pair of bellows; to avoid circumlocution, he calls it the sound of exten- sion ; 3d, a prolongation and possibly an aug- mentation of this sound by the sonorous vibra- tions peculiar to muscular fibre." Dr. C.J. B. Williams has very justly objected to the correct- ness of the second cause here adduced as aiding in the production of the first sound, as the phrase " sound of extension" is obviously contradictory when applied to a contracting muscle.f Dr. C. J. B. Williams maintains " that the first sound is produced by the mus- cular contraction itself," the clearness of which is increased by the quantity of blood in the heart " affording an object around which the fibres effectually tighten, whilst the auricular valve, by preventing the reflux of the blood, increases its resistance, and thus adds to the tension necessary for its expulsion." He was first led to the adoption of this opinion by the observations of Enman and Wollaston upon the existence of a sound accompanying every rapid muscular contraction. This opinion he afterwards put to the test of experiment, the results of which we give in his own words. " Experiment 1st, observation 8th; I pushed my finger through the mitral orifice into the left ventricle and pressed on the right so as to prevent the influx of blood into either ventricle ; the ventricles continued to contract strongly (especially when irritated by the nail of the finger on the left), and the first sound was still distinct, but not so clear as when the ventricles contracted on their blood. Observation 9th. The same phenomena were observed when both the arteries were severed from the heart." He also found in other observations that the first sound was louder over the surface of the ven- tricles than over the origin of the large arteries, which is in direct opposition to the opinion of those who believe that this is produced by the rush of blood along the great arteries. That the first sound is not dependent upon the closing of the auriculo-ventricular valves, he also ascertained from observations, in which the closure of these valves was partially or com- pletely prevented, and yet the first sound was still heard. Besides, this sound continues during the whole of the ventricular systole, while the shutting of the valves must take place and be completed at the commencement of the systole." That the collision of the particles of As Mr. Carlisle is a member of the Dublin Heart Committee, we must now consider him as concurring with the report of that Committee, t Medical Gazette, Sept. 1835. fluid in the ventricles does not produce this sound he was convinced from observations, in which it continued although there was no blood in the ventricles. Though we must admit that these experi- ments of Dr Williams prove that part at least of the first sound is caused by the muscular contraction of the ventricles, yet we must con- sider it still problematical, until we obtain further observations, whether it produces the whole of that sound, for it is very possible that some of the other circumstances attending the systole of the heart may increase its intensity. M. Marc d'Espine has maintained that both sounds depend on muscular movements; the first sound upon the systole, and the second upon the diastole of the ventricles. The Dub- lin Committee have in the meantime concluded that the first sound is produced either by the rapid passage of the blood over the irregular internal surface of the ventricles on its way towards the mouths of the arteries, or by the bruit musculaire of the ventricles, or probably by both these causes. We must wait for further experiments before this question can be fairly settled .* Second sound. — Later experimenters appear to be more nearly agreed about the cause of the second sound than that of the first sound. M. Rouanet appears to have been the first who publicly maintained the opinion that the second sound was dependent upon the shock ot blood against the semilunar valves at the origin of the aorta and pulmonary artery. M. Rouanet himself acknowledges that he owed the sug- gestion to Dr. Carswell, at that time studying in Paris, who came to that conclusion by a beautiful process of reasoning upon the pheno- mena which presented themselves in a case of aneurism of the aorta. The same opinion has been supported by Billing, Bryan, Carlisle, and Bouillaud.f It is, however, to Dr. C. J. B. * The London Committee, in their report given in at the meeting of the British Scientific Associa- tion for 1836, have adduced some additional expe- riments in favour of the opinion that the first sound of the heart depends upon muscular con- traction. It appeared to them that the sound pro- duced by the contraclion of the abdominal muscles as heard through a flexible tube resembles the systolic sound. They, however, admit that though " the impulse is not the principal cause of the first sound, it is an auxiliary and occasional cause, nearly null in quietude and in the supine posture, but increasing very considerably the sound of the systole in opposite circumstances." From the great care with which these experiments appear to have been performed, we believe that we are now fullv justified in adopting this explanation of the cause of the first sound. The Dublin Committee, in their report given in at the same time, also detail some experiments which they believe to be confirmatory of their former conclusions. See Sixth Report of British Scientific Association. t In justice to Dr. Elliott, of Carlisle, I must state that I find, on consulting his Thesis De Cordc Humano, published in Edinburgh in 1831, that he states (p. 53) that he believes that the second sound of the heart is dependent upon the rush of blood from the auricles into the ventricles during their diastole, and also upon the sudden flapping inward of the sigmoid valves at the origin of the large arteries by the refluent blood. 618 HEART. Williams that we owe the first direct experi- ments in support of it. In one experiment he ascertained that the second sound was louder over the origin of the large arteries than over the surface of the ventricles, while it was the reverse with the first sound; that pressure upon the origin of the aorta and pulmonary artery suspended the second sound ; and that the second sound disappeared after the auricles had been laid open, although the first conti- nued. In a second experiment* we find the fol- lowing observations stated : — " Observation 6. A common dissecting hook was passed into the pulmonary artery, and was made to draw back and thus prevent the closure of the semi- lunar valves ; the second sound was evidently weakened and a hissing murmur accompanied it. A shoemaker's curved awl was then passed into the aorta so as to act in the same way on the aortic valves. The second sound now entirely censed and was replaced by a hissing. Observation 7. The hook and the awl were withdrawn ; the second sound returned and the hissing ceased. Observation 8. The experi- ment 6th was iepeated with the same result, and whilst Dr. Hope listened I withdrew the awl from the aorta. He immediately said, ' Now I hear the second sound.' I then removed the hook from the pulmonary artery ; Dr. Hope said, ' Now the second sound is stronger and the murmur has ceased.'" The Dublin Committee have repeated and con- firmed these experiments of Dr. Williams. In tlieir experiments one of the valves in each artery was transfixed and confined to the side of the vessel by a needle, and the second sound disappeared ; on withdrawing the needles they re-appeared. As the second sound thus appears to be pro- duced by the shock of the blood upon the semi- lunar valves, its intensity must, in a great measure, depend upon the diastole of the ven- tricle drawing part of the blood back upon them, but perhaps more particularly upon the elasticity of the large arteries returning suddenly upon their contents during the diastole of the ventricles, when the distending force of the ventricles has been withdrawn. We would therefore expect that the second sound should be louder in those whose aorta retains its elas- ticity, than in those (a circumstance sufficiently common in old age) in whom, from a morbid alteration of the structure of its coats, the elasticity is either lost or greatly diminished. This is an observation which, as far as I know, has not yet been verified ; but my friend Dr. VV. Henderson informs me that he is positive from numerous observations that the second sound is louder in young than in older persons ; but whether this is in the exact ratio of the change upon the elasticity of the coats of the large vessels he is not at present prepared to say. * These experiments were performed upon asses, in which the sensation was first suspended by a dose of wourara poison and then maintaining arti- ficial respiration. In this manner the heart con- tinued to act upwards of an hour after the com- mencement of the artificial respiration. Bibliography.— as a complete bibliography of the Anatomy and Physiology of the Heart would include all the systematic works on Anatomy and Physiology, we shall here confine ourselves to the enumeration of those works and memoirs which treat exclusively or in a prominent manner of the normal anatomy or functions of that organ. Harvey, De motu cordis, Rot. 1661. Lower ( Richard ), Tractus de corde, &c. Lond. 1669. Pechlinus ( John Nicol ), Dissertat. de fabrica et usu cordis, Riel. 1676. Bartholin ( Casp.), Dis- sert, de cordis structura et usu, Hafnise, 1678. Charleton ( Walter ), The organic structure of the heart, Lond. 1683. .Morton (C), Dissert, de corde, Lugd. Batav. 1683. Bellini ( Laurent.), Opuscula aliquot de urinis, de motu cordis, &c. Lugd. Bat. 1696. 4to. Chirac ( Peter), De motu cordis adversaria analytical Montp. 1698. Vieus- sens, Nouvelles Decouvertes sur le cceur, Montp. 1706. Traite nouveau de la structure du cceur, &c. Toulouse, 1715. Thebesius, De circnlo sanguinis in corde, Leipsick, 1708. Ibid. De circulo san- guinis per cor, Leipsick, 1759. Borelli (J. A.), De motu animalium, Lugd. Bat. 1710. Winslow, Surles fibres du cceur et sur ses valves, Mem. do I'Acad. Roy. de Paris, 1711. Morgagni ( Jo.Bapt. ), Adversaria Anatomica, Lugd. Bat. 1723. Santo- rinus, Observ. Anatomies, Venise, 1724, cap. viii. Ruysch, Epist. Anat. problemata decima de auri- cularum cordis earumque fibraruin metriciam struc- tura, Amsterdam, 1725. Lancisi ( Jo. Mar.), De motu cordis, Sec, Rom. 1728. fol. Op. Om. torn. iv. 1745. 4to. Walther, De structura cordis auricu- larum, Leipsick, 1738, reprinted in Haller's Dis- put. Anat. torn. ii. 1747. Stuart ( Alex.) De motu et structura musculari, Lond. 1738. Examen de la question si le coeur se raccourcit on s'alonge lorsqu'il se contracte, Mem. de I'Acad. de Paris, vol. i. p. 114. 1743. Senac, Traite de la struc- ture du coeur, de son action, &c. Paris, 1749. torn. i. and Appendix to torn. ii. Lieutaud, Observ. Anatom. sur le coeur, dans Memoires de I'Acad. de Paris, 1752-54. Haller ( Albertus ), Memoires sur la nature sensible et irritable des parties du corps animal, Laus. 1756. torn. i. Ibid. Elementa Physiologic, torn, i 1757. This last work, and the Traite de la Structure du Cceur, &c. of Senac, contain a most accurate and detailed account of all that was known upon the Anatomy and Physiology of the Heart before and at the time they were written. Wolff ( C. F.), Dissertationes de ordine fibrarum muscularum cordis, in Acta Acad. Petro- polit. 1780-1792. Abernethy ( John ), Observations on the Foramina Thebesii of the Heart, Phil. Trans. 1798. Legallois, Dictionnaire des Sc. Med. torn. v. 1813. Gerdy ( P. N.j, Journal Compl. du Diction, des Sc. Med. torn. x. 1821. Recherches, Discussions, et Propositions d'Anatomie, Physio- logie, &c. 1823. The plates given by Gerdy in the latter work have been copied by M. Jules-Cloquet in his Planches d'Anat. de l'Homme, Sec. torn. iv. Vaust ( J. F.), Recherches sur la structure et les mouvemens du coeur, Liege, 1821. Memoirs exclusively on the relative sixe of the several cavities of tJie heart. — Helvetius, Sur Pinegalite de capacite qui se trouve entre les organs destines a la circulation du sang dans le corps de l'homme, &c. Mem. de I'Acad. de Paris, 1718. Weiss, De dextro cordis ventriculo post mortem ampliore, Altdorf, 1745. Avrivillius, De cavit. cordis inaequali amplitudine, &c. Haller, Disp. Anat. Sel. vol. viii. pars ii. p. 257. 1751. Sabatier, Mem. de I'Acad. de Paris, 1774. Treatises exclusively on the nerves of the heart. — Neubauer (J. E.), Descriptio nervorum cardiaca- rum, Frankfort et Leipsick, 1772. Andersch, De- script, nerv. cord, in torn. ii. Ludwig Script. Neurol. 1792. Behrends (Jo. B. 0.), Dissertatio qua. demonstratur cor nervis carere, Mayence, 1792 ; reprinted in torn. iii. Ludwig Script. Neu- rol, torn. iii. 1793. Zerenner, An cor nervis careat iisque carere possit ? Erford, 1794 ; reprinted in FIBRES OF THE HEART. 019 torn. iv. LudVig. Script. Neurol. 1795. Scarpa, Tabulae Neurologicae, &c. Ticin. 17:J4. Memoirs on the peculiarities of the foetal heart. — Memoirs upon the Foramen Ovale by Duverney, Mery, Bussiere, and Littre in Mem. de 1'Acad. 1699 to 1703. Winslow, Sur une nouvelle valvula de Ja venae cavae inferior, qui pent avoir rapport a la circulation du sang dans le foetus : Mem. de l'Acad. 1717. Eclaircissement sur un Mem. de 1717. Ibid. 1725. Haller (Albert), De Valvula Eustachii, G'dtting. 1737, et in Disp. Anat. torn. ii. 1747. Brendelius, De valvula venae cavae, Wit- temberg, 1738 ; reprinted in Opusc. Math, et Med. Pars i. Lobstein ( J. F.), DeiValvula Eustachii, Strasbourgh, 1771. Sabatier, in Mem. de l'Acad. 1774. Wolff, De foramine ovali, &c. in Nova Comment. 1'etropol. t. xx. Kilian, Kxeislauf im Kinde, &c. Karlsruhe, 1826. Biel (Guil.), De foraminis ovalis et ductus arteriosi mutationibus, 1827. Berlin. Jeffruy, Peculiarities of the foetal circulation, Glasgow, 1834. Edinb. Med. and Surg. Journ. 1835. On the sounds of the heart. — Laennec, Traitc de 1' Auscultation Mediate, &c. Paris, 1819. Forbes's translation, 4th edit. 1834. Turner (John W. ), 3 vol. Med.-Chirurg. Trans. Edinb. 1828. Wil- liams ( Dr. David ), Edinb. Med. and Surg. Journ. vol. xxxii. 1829. Corriyan, Dublin Med. Transact, vol. i. 1830. Stokes and Hart, Edin. Med. and Surg. Journ. 1830. Sjnttal ( Dr. R.J, Treatise on Auscultation, Edinb. 1830. Rouanet, Journal Heh- dom. No. 97. Pigeaux, Journal Hebdom. torn. iii. p. 239, et torn. v. p. 187, for 1831, et Archiv. Gen. do Med. Juillet ct Novembre, 1832. Billing, Lancet, May, 1832. Hope, A Treatise on Dis- eases of the Heart and great Bloodvessels, 1st edit. 1832. Appendix to 2d edit. 1835. Bryan, Lancet, Sept. 1833. Piorry, Archiv. Gen. de Med. Juin, 1834. Newbiyginy ( Dr. P. S. K.J, Inaugural Dis- sertation on the impulse and sounds of the heart, Edin. 1834. Carlile, Dublin Journal of Medical Science, vol. iv. 1834, and Transact, of British Scient. Assoc. vol. iii. 1834. Mayendie, Jjancet, Feb. 1835. Medical Gazette, vol. xiv. Bouilland, Traite clinique des maladies du coeur, torn. i. 1835. Williams ( Dr. C. J. B.J, The Pathology and Diag- nosis of Diseases of the Chest, 3d edit. 1835, and Medical Gazette, Sept. 1835. Report of Dublin Committee for investigating the sounds ' of the Heart, Dublin Journal of Medical and Chemical Science, Sept. 1835, and Transactions of British Scient. Assoc. vol. v. Beau, Lancet, Feb. 1836. Spittal (Dr. R.), Edin. Med and Surg. Journal, July, 1836. Reports of the London and Dublin Committees for investigating the sounds of the heart. Transactions of Biitish Scientific Asso- ciation, vol. vi. 1837. ( John Reid.) ON THE ARRANGEMENT OF THE FIBRES OF THE HEART— [The Editor hopes that the following detailed account of the researches of Mr. Searle on this difficult point of minute anatomy will not be deemed unacceptable. Any reference to the labours of other anatomists has been rendered unnecessary in consequence of that part of the preceding article which bears upon this subject.] Prcliminari/ remarks. — In order to unravel the fibres composing the ventricles of the heart, considerable preparation is necessary. The auricles, fat, coronary vessels, and external pro- per membrane should be cleanly dissected off; the heart should then be boiled thoroughly, but not too much, so as to give its fibres the requi- site degree of firmness without rendering thern fragile. For example : sheep's hearts should be boiled ten or fifteen minutes ; calves' twenty or thirty, and bullocks' forty or fifty minutes ; immediately afterwards they should be im- mersed in cold water ; for if they be exposed to the air while hot, their superficial fibres be- come dark, dry, and brittle. As the process of unravelling occupies many hours, and as the heart requires to be preserved in a good condi- tion, it should be immersed during the intervals in weak spirit and water. The heart of the calf is preferable to that of any other animal, it being on a scale which affords distinct views, while the fibres of young are more easily sepa- rated than those of older animals. The con- formation is the same in all quadrupeds, and bears a complete resemblance to that of the human heart. When the coronary vessels are dissected off, a depressed line or track is left on the anterior and posterior surfaces of the heart. Since this line corresponds externally to the entire edge of the septum, and to the boundary of the right ventricle, it may be usefully em- ployed in reference to these patts. It is there- fore denominated the anterior or posterior co- ronary track, accordingly as it pertains to the anterior or posterior surface of the heart. The fibres of the heart are not connected together by cellular tissue as are those of other muscles, but by an interlacement which in some parts is very intricate, and in others scarcely perceptible. At the entire boundary of the right ventricle they decussate, and become greatly intermixed ; at the apex and base of the left ventricle they twist sharply round each other, and so become strongly embraced ; but in ge- neral the interlacement is so slight that they appear to run in parallel lines. Whether a mere fasciculus or a considerable mass of this last description of fibres be split in the direc- tion of the fibres, a number of delicate parallel fibres will present themselves, some being stretched across the bottom of the fissure per- fectly clean and free from any connecting medium whatever; and although some must necessarily be broken, yet these are so few that they do not attract attention unless sought for. In this process of separation very little resistance is offered ; and none that is appreciable when a single fibril is taken hold of by the forceps, and stripped off, and which could not be done if bound down by cellular membrane. If a piece of common muscle be afterwards split, it will be found to offer great resistance, and to be attended with so much laceration of the fibres, that instead of a beautiful series of fine muscular threads arranged in parallel lines, a ragged mass of mutilated fibres appears; and during the process of separation, the cel- lular substance is seen not only to connect the fibres, but to afford the resistance which is ex- perienced. This comparison obtains in the undressed state of the specimens ; but when cooked, other distinctions are met with. For example : in whatever direction a roasted heart be sliced, its cut surface is uniformly smooth, not grained like other muscles when dressed ; and it eats short, not offering that elastic resistance which other muscles do during mastication. The absence of cellular substance as a con- 620 FIBRES OF THE HEART. Fig. 278. CpcaaajvO Fie.. 279. Fie. 280. Fig. 281. Cj?caa .Cacc Ca.cc Fig. 282. CRO necting medium among the fibres in question mined the fibres with me, could detect its exist- is not only proved by the absence of its physi- ence. ,.„.,. „ „ , , cal characters, but by its not being discovered Since the chief utility of cellu ar membrane through the medium of the microscope. Nei- in investing and connecting together the fibres ther Mr. Kiernan nor Mr. Goadby, who exa- of a muscle is, most probably, that ot retaining FIBRES OF THE HEART. 621 them within their proper spheres of action, and since the fibres of the heart are devoid of this agent, the question arises as to what other retaining power these possess. On this head no difficulty presents itself; for the fibres, in winding round and round the cavity of the left ventricle, become arranged in concentric layers ; and in taking a larger sweep, in surrounding the right ventricle, the same arrangement is preserved, so that during the systole of the heart the whole mass of the fibres firmly com- press each other, which necessarily retains them all within their proper spheres of action, ex- cepting the superficial fibres, of which those towards the base, and especially those upon the right ventricle, where there is great latitude of motion, do not preserve a parallelism with their subjacent fibres, but lie nearly at right angles with them. It is on this account, most proba- bly, that the superficial fibres have attracted notice, and have been viewed as a distinct layer. The disposition of the fibres varies in diffe- rent parts of the heart, forming parallel lines, angles, decussations, flat and spiral twists. The fibres are arranged in fasciculi, bands, layers, and a rope, which are so entwined together as to form the two chambers called the right and left ventricles. These are lined with their in- ternal proper membrane. The fasciculi are connected with the aorta, pulmonary artery, and carnea? columnar, and contribute to the formation of the bands. The bands. — By tracing the fibres in bands, we are enabled to develop the formation of the ventricles in a progressive and systematic man- ner. The bands spring from a mass of fibres which forms the apicial part of the left ventricle, and which, in winding round just above the apex of the heart, separates into two bands to form the right ventricle. It will render the demonstration more intel- ligible if a preliminary and cursory view be taken of the general course of these bands (fig. 283, p. 626,) by referring to the diagram. The bands, as there given, form a mere skeleton of the heart, merely indicating the se- veral courses they take. The average width of the bands is not less than a third of the extent between the apex and base of the left ventricle. In the diagram, crc indicates the winding of a considerable mass of fibres just above the apex; at the septum, s, it splits into two bands. The shorter, Cacc, encircles spirally both ventricles, one half round the right, the other round the left ventricle. The longer band de- scribes two circles : it first passes through the septum, round the left ventricle marked Cpca ; it secondly passes round the base, and includes both ventricles in its circuit, marked progressively Cpcaa, Cpcaaa, CpcaaaaC, and RE. After employing so many letters, it is requi- site to explain that as the bands are frequently receiving fresh accessions of fibres, it is desira- ble to characterise those increments individually by the initials of the names of the respective sources from which they are derived; and in order to make a distinction between the indica- tions of the fibres and of their respective origins, the latter are characterised by double, and the former by single initials. Accordingly, the aorta, the pulmonary artery, the rope, and the carneae columnar are designated aa, pp, kr, and cc, while their fibres are marked a, p, r, and c. This plan is modified in one instance only, viz., the fibres of the main bulk of the heart, being derived from the rope and the two carnea? columnse of the left ventricle, are desig- nated in the first instance by their proper ini- tials crc ; but as numerous increments of fibres are being made, in succession, to these three original sets, it is convenient to make an abbreviation in the lettering; thus, crc is in- dicated by C large, when combined with other initials ; accordingly, crca is con- tracted to Ca, and crcpca to Cpca, and so with the rest. The layers.- — Although the heart admits of being split into a number of layers, yet there being no material division formed by fasciae or condensed cellular membrane, such separations are strictly arbitrary. It is, however, found convenient to separate the fibres into certain layers, in order to give a methodical de- monstration of the formation of this organ. The same remarks obtain regarding the bands. It is generally supposed that the superficial fibres properly constitute a distinct layer, form- ing a common sac, which encloses the two ventricles. This is not strictly the case, for it lias the same origins and terminations as have the fibres immediately subjacent to it. Neverthe- less, the superficial fibres are, in the following description, considered as a separate layer, to show the peculiar construction of the apex. The rope. — It has already been stated that the longer of the two bands terminates at the base in the rope. The fibres of this band, in forming the brim of the left ventricle, make a sharp twist like those of a rope, by which means they become the inner fibres of this chamber, and expand into a layer which enters largely into the formation of the mass which divides into the two bands. So the principal band, although it receives several increments of fibres, has no complete beginning nor ending, a considerable portion of it originating and ter- minating in itself, which circumstance renders it necessary to fix upon the most convenient part of its course for the commencement of the demonstration. Although the system here adopted of unra- velling the fibres of the heart be strictly arbi- trary, as every other must be, yet it will, most probably, be found the only method by which all the various courses, and several connexions made by the fibres in forming the heart, could be displayed. The demonstration. — It is requisite to pur- sue two methods of demonstration ; — one, de- scribing the dissection, or unfolding, which consists in unravelling and separating the fibres, and tracing, from the circumference to the cen- tre of the heart, their various courses, in the form of bands, by which they become in order unwound, and by which a general view of the formation of the two ventricles is at the 6*22 FIBRES OF THE HEART. same time presented. The other, describing the formation, or winding up of the fibres, comprehends the retracing of the fibres from the centre to the circumference, showing their respective origins, associations, courses, con- nexions, and terminations, also the manner in which they are wound up to form the two ven- tricles into one compact conical body. The dissection. — The first stage consists in separating the superficial fibres from the two ventricles, which, perhaps, cannot be accom- plished in a more simple manner than by rais- ing them in the forms of two wings and a tail, as represented in fig. 279, which is to be done by commencing at the anterior coronary track, cutting through the superficial fibres and de- taching them by means of a blunt scalpel in their natural direction, so far as their insertions at the base ; this will be found to divest the right ventricle, and, from their obliquity, a part of the left. (See the left wing, Cacc) Then recommencing at the anterior coronary track, the fibres should be separated in the contrary direction, over the left ventricle towards the apex. These fibres take a very 6piral course, and as they approach the apex converge, but on reaching it they twist sharply round upon themselves, like the fibres of a thick cord, and entering at the apex become the internal fibres of this chamber. The remaining part of the superficial fibres, extending from the apex to the base, pertains exclusively to the left ventri- cle; these should be divided an inch or two above the apex, and the apicial portion detach- ed, which will complete the tail, Crc. Its fibres are represented, as they appear after sepa- ration, untwisted. The basial portion of these fibres should now be detached so far as the annulus arteriosus, and reflected like the right wing, Crc. These, as do most other fibres which approach the base, take a more longitu- dinal course, and in general they become so separated as they diverge to encompass the basial part of the heart, that they cannot be raised in an entire layer unless some of the subjacent fibres be taken with them. The second stage of the dissection comprises the disconnecting the bands which compose the outer or proper wall of the right ventricle. The superficial layer of fibres having been re- moved, there remain two other layers pertain- ing to this wall of the ventricle, viz. the middle and the internal. The middle is separable into two bands, the upper or basial, and the lower or apicial. It is better to detach the apicial band first, which makes one spiral circle round the heart. Its outer extremity being attached to the root of the aorta at its anterior face, and sometimes to the pulmonary artery also, an in- cision should be made extending from the up- per part of the anterior coronary track obliquely towards the annulus arteriosus, which incision should, in a calf's heart, be a little more than an inch in length and a tenth of an inch in depth. The band should then be detached agreeably to its spiral course from the base and middle third of the left, and from the lower half of the right ventricle, as far as the anterior co- ronary track, the line from which the separation commenced. It here receives on its posterior surface a considerable accession of fibres from the right surface of the septum, by the junction of which this part of the boundary of the ven- tricle is formed, but the further separation of the band prevented. In fig. 281, in the first or basial part of its course it is indistinctly seen, marked Cacc In fig. 282 its middle course may be traced, although the half circle of the band which wound round the left ventricle has been cut off. In the preparation exhibited in this figure the separation of this band could not be effected under the posterior coronary track, on account of the separation having been con- ducted too deeply, where the fibres decussate to form the posterior boundary of the right ven- tricle. In fig. 281, which exhibits a dissection of the right ventricle of a bullock's heart, the whole of the band, Cacc, is separated as far as the anterior boundary of this cavity, and lies extended ; and the accession of fibres it re- ceives from the right surface of the septum are seen prolonged into it. The basial band crosses the upper half of this ventricle. It cannot be raised from its situation on account of the numerous lateral connexions it forms in its progress with the margins of the orifices of the aorta, pulmonary artery, and annulus venosus. In order to de- tach it as far as it will admit, an incision about half an inch on the right side of and parallel with the anterior coronary track, should be made, extending from its lower edge to the base, and an eighth of an inch in depth, or as deep as will expose the fibres from the pulmo- nary artery, which in general pass at an angle with those of the band. Although this band cannot be disconnected from the base, it can in general be detached from the fibres of the sub- jacent layer, so far as the posterior coronary track; sometimes, however, they are too inter- woven to admit of any separation. The first part of this band is represented in fig. 281, marked Cpcaa; it was divided more than half an inch from the anterior coronary track. Its continuation may be seen in fig. 2B2, lettered Cpcaaa, where it is evidently not discon- nected from, but merely raised towards the base, and if replaced would overlap the fibres taking the middle course round the heart. The depression at the line of the posterior coro- nary track, pet, is occasioned by the band being bound down at the base and at its under sur- face also, by which means the upper half of the posterior boundary of this ventricle is formed. As the further pursuit of this band pertains to the third stage, it will be made hereafter. The internal layer. By the separation of the two former bands the internal layer is ex- posed. It is composed of fibres from the pul- monary artery and from one of the carneaj co- lumnae. In fig. 281 the fibres, pc, are seen arising from the root of the pulmonary artery at its entire circumference, first forming a channel and then expanding into a layer, which, in pro- ceeding obliquely across the cavity, obtains an accession of fibres from one of the carneaj co- lumna;, which is not brought into view, and which, on reaching the line of the posterior FIBRES OF THE HEART. 623 coronary track, joins a band emerging from the septum, and tnus forms the apicial half of the posterior boundary of this ventricle. It is raised from its situation, but when replaced its edge, which is everted by the probe, appl.es itself to the anterior boundary of this cavity. This layer cannot often be so extensively dis- connected from its superjacent bands as this figure represents. The third stage of the dissection. — Having separated the layers composing the right or proper wall of the right ventricle, the next pro- ceeding consists in detaching and unwinding the band and layers composing the left ventri- cle. First, the detachment of the basial band. As this band has already been detached over the right ventricle in the second stage of the dissection, it is necessary to resume its separa- tion at the posterior coronary track. But as the further separation is somewhat difficult, it will be rendered less so if the remaining portion of this band be first examined in fig. 282, wherein it is represented detached. When in its natural situation it forms the uppermost third of this, the left ventricle, and its lower fibres overlap a part of those which occupy the middle third. The fibres which overlap the others in taking an oblique course towards the base reach the brim of the ventricle and pass over it, while the under fibres of this band are appearing in succession, and taking a similar spiral course until the whole bundle of fibres is twisted in the form of a rope. In order, there- fore,to trace ou t and detach this band as it becomes transformed into a rope, it is requisite to com- mence near the posterior coronary track (pet ), in a continuous line with the lower edge of its former portion, introducing the handle of a scalpel obliquely upwards so as to detach the fibres which overlap those of the middle third, and to carry the separation so far up as will reach those marked a, coming obliquely down from the aorta. In conducting this separation from left to right it is soon found that the fibres of this bundle, instead of overlapping others, become themselves by twisting overlapped, rendering it necessary, therefore, to turn gra- dually the handle of the scalpel obliquely downwards, tracing the rope according to its windings. Two scalpels will be required in conducting the further separation. The next step should be preceded by viewing the fibres of the rope in fig. 280, descending and radiating into a layer which sweeps round the cavity of this ventricle. The heart should now be placed in a small cup or jar of a size that will support it with its base upwards, and then, with the scalpels employed vertically, the separation should be proceeded with, and in passing through the septum a vertical section should be made through the aorta in the line of separation, which should be pursued round and round, and progressively deeper until the handles of the scalpels perforate the external fibres, which, if they have been rightly inclined, they will do a little above the apex of the left ventricle, just after they have completed the division through the layers of the septum. The band of fibres occupying the middle third of the heart, and which now pass over the scal- pels, should be divided; the incision being made along the side of the posterior edge of the septum. A section should be made through the rope also, which allows the right ventricle to be raised from the left, and the heart to be unwound as far as the separation has been car- ried. There yet remains a mass of fibres around the cavity of the left ventricle to be de- tached. This last process of separation should be conducted in a contrary direction to that which has hitherto been adopted, viz. from right to left, until the internal membranous lining is exposed, and which should be torn in order to lay open this chamber. The heart can now be unwound and extended as in fig. 278, placing the left ventricle, Iv, at one end and the right at the other, removing that section of the aorta, aa, connected to the right ventricle from its counterpart which ex- clusively pertains to the left, and which is hid- den by the rope, rr ; removing also the two portions of the bisected rope to the two most distant diagonal points in this view. The niche, Cpc, indicates the part occupied by the divided band which passed along the mid- dle third of the heart. The second method of demonstration. — The formation, or winding up of the fibres, of the heart. This description comprehends the retracing of the fibres from the centre to the circumference, showing their respective origins, associations, courses, connexions, and terminations, also the manner in which they are wound up to form the two ventricles into one compact conical body. The first stage consists in retracing the su- perficial layer from its origins to its termina- tions. It is necessary to commence at the very centre of the heart — the interior of the left ventricle, whence spring the fibres composing its main bulk. Fig. 278, at its right extremity, exhibits the left ventricle, Lv, laid open, exposing the two carneae columnar, cc and cc, one of which is placed out of its situation, in order to show the interior of the chamber. The fibres of the two carneae columns, cc and cc, ex- pand in a fan-like manner ; those of the rope, rr, expand in a similar manner ; the radiated fibres of each of these three bodies wind round the axis of this ventricle forming its parietes ; and as they wind so as to form an inverted cone, it is clear that the inmost fibres alone can reach the apex. Accordingly, a fasciculus of the inmost fibres from each of these three bodies, marked c, R, and c respectively, pass down to the apex associated together, and in their course make a gentle twist from left to right, gradually contracting the cavity to a point and closing it ; they then twist sharply round upon each other and complete the apex marked cite conjoint! i/, so that by means of this twisting the internal fibres are rendered external. These excluded fibres now enter into the formation of the superficial layer, and form the tail of fig. 279. They take a very spiral course near the apicial part, and over the an- terior surface of the left ventricle as far as the anterior coronary track ; but as they approach 624 FIBRES OF THE HEART. the base, pass more longitudinally. It is evi- dent that these few fibres would be inadequate to form a complete layer, unless in their pro- longation they pursued an uniformly spiral course. They are more than enough to cover the apicial part as they twist over each other; but in consequence of the conical form of the heart they soon become singly arranged, and as they diverge, separate and leave interspaces, some of which are occupied by fibres which apparently arise abruptly at the surface. The fibres which pass longitudinally to the base of the left ventricle are inserted into the tendinous margin of the annulus arteriosus, and into the posterior part of the root of the aorta, forming the right wing, crc. The spiral fibres have been stated to arrive at the anterior coronary track along its whole length. The majority of them terminate at the coronary vessels ; others are merely intersected by them, while others pass under these vessels and become super- ficial again : those which maintain their course over the right ventricle vary in different hearts from a small to a considerable number. Along the whole length of this track accessory fibres from the interior of the right ventricle are emerging to associate with these in their way over this ventricle. They take a longitudinal course to the base, and therefore start at an angle with the spiral fibres which are on the left side of the coronary track. In fig. 281 these accessory fibres from the aorta, a a, and from two of the carnes columns, are seen passing together obliquely down the right sur- face of the septum, marked acc, to enter into the formation of the extended band. These accessory fibres perforate it along the anterior boundary, ab, and become super- ficial. This layer is, accordingly, in jig. 279, marked Cacc; its fibres pass at nearly right angles with the subjacent fibres, and when raised form the left wing; its insertions are the anterior part of the root of the aorta, the tendinous margin of the annulus venosus, and again the right part of the root of the aorta. Sometimes festoons are formed at the base by communications of fibres between the pulmo- nary artery and the aorta, at its right and pos- terior aspects. It occasionally happens that the accessory fibres which arise from the interior of the right ventricle are not very numerous; in such cases a greater number of fibres arise abruptly from its surface. The superficial layer has three sets of ori- gins: one, primitive, from the interior of the left ventricle; the others, accessory, from the interior of the right ventricle, and from the outer surface of both. It cannot with pro- priety be considered as one common invest- ment, since each ventricle for the most part gives birth to its own superficial fibres. It is necessary to raise it as a distinct layer for two reasons : first, that the superficial fibres of the right ventricle in general pass nearly at right angles with their subjacent fibres, and there- fore require to be removed in order to proceed with the next stage of separation : secondly, that it developes the peculiar mode of closing the left ventricle, and of forming the apex ; and probably no other method than that of the twisting of the fibres could have been so secure, especially as the parietes at the apex of the ventiicle do not generally, even in a bullock's heart, exceed a tenth of an inch in thickness. The secund stage — The external layer having been traced from its origins to its insertions, we may now trace the deep-seated layers ; and as these have, for the most part, the same origins, courses, and insertions as the super- ficial layer, we may commence the description at the same points. It has been already stated that the fibres of the rope and of the two earner columns ex- pand in a fan-like manner, that their inmost fibres pass through the apex and become ex- ternal, but that the chief of them wind round the axis of the left ventricle above the apex, as exemplified in fig. 279, crc. The respec- tive sets of fibres pertaining to these three bodies continue separate during their radiation only, after which they become plaited together by folding one over the others. Their mode of association is shown in the extended portion of the split layer, crc in fig. 280, also in its counterpart, crc, winding round the api- cial part of the ventricle. Again, in fig. 278, it may be seen that the fibres at the bases of these columns turn under and pass up in con- junction with those of the rope forming the middle mass, cue, at the upper of which they fold over making flat twists upon them- selves, which have, however, become exag- gerated in appearance by the unwinding of the heart, as in rolling it up again some of the angles are converted into spires, preserving a considerable degree of parallelism. Having shown the origins, and the method adopted in the association, of the fibres form- ing the middle mass in jig. 278, we proceed by tracing the divisions and prolongations of its fibres, and the plan of building up the two chambers of the heart. First, the forma- tion of the left ventricle. If the right carnea columna, cc, be replaced in contact with its fellow, and if the rope, rr, be brought round the upper part of this cavity so as to embrace them, and if portion 4 be split from the middle mass, crc, and be wound, in association with the apicial fibres, crc, round the lower part of this cavity, that division of the heart, comprising the left ventricle and the middle mass, will bear a near resemblance to that represented in fig. 280 ; in which figure the rope, rr, in embracing the heads of the carnes columns, cc, brings into view its fan- like fibres, r, sweeping round the upper part of the axis of this ventricle ; in which the fibres of portion 4, in winding round the lower half of the axis, embrace the bodies of the carnea; columns, cc, and associate with the apicial fibres, crc, and in which the ex- tended layer, cue, represents the middle mass minus the portion 4, which is split from it. Thus much pertains exclusively to the descrip- tion of the formation of the left ventricle. That of the right is more complicated, and constitutes — FIBRES OF THE HEART. 625 The third stage. In pursuing the mass of blended fibres, crc, occupying the middle of fig. 278, it is found that, after having formed the left, it splits under the line marked by stars into two bands, which embrace and con- tribute to form the right ventricle. These sepa- rated bands were stated in the preliminary remarks to be of unequal lengths, the longer making two and the shorter making but one spiral circle round the heart. The longer, in the first place, assumes the character of a layer and forms the middle layer of the septum. It requires to be described in three portions. Portion 1, being attached to the valve of the other section of the aorta, was stripped off in unwinding the heart ; in the wound-up state it passes over the pulmonary channel of fibres, p, along the part marked 1, in its way to the aorta, a a ; its absence, however, opens to view the fibres coming from the base and form- ing the right layer of the septum. Portion 2 proceeds from the starred line across to enter into the formation of the rope, Rit, and will be noticed hereafter. Portion 3 is the longer band; it is not entirely seen, being overlapped by some of the fibres of portion 4 ; it passes across to the niche, Cpc, where it was di- vided in unwinding the heart, in order to liberate the two ventricles which were encircled together by this band. Previously to pursuing this band further, it is better to trace it as the middle layer of the septum in its natural situ- ation— the wound-up state of the heart. In fig. 280 it forms the extended layer, crc, in association with portion 2, and split from por- tion 4, which does not belong to the septum ; on being replaced, its cut edge, a, applies to the cut edge, b, in passing as the middle layer between the right and left layers of the septum. The middle layer is seen in fig. 282 emerging at the posterior edge of the septum, where portion 2 disconnects itself to join at the under surface the band above, but in this figure is marked C large, indicating that it is derived from this layer, which has hitherto been lettered crc. This layer, being now deprived of all its other portions, will hereafter be considered as a band, and it has already been explained why it should be denominated the longer band. This band in emerging at the posterior edge of the septum is joined by another band of fibres, which is seen in fig. 281, forming part of the internal layer of the proper wall of the right ventricle; its fibres, pc, arise from the pul- monary artery, pp, and from one of the carneae columnae not in sight ; they cross ob- liquely over this cavity to the posterior edge of the septum to join the band in ques- tion. By the intimate blending of the fibres of these two bands the apicial half of the posterior boundary of this ventricle is constructed. The longer band, now aug- mented, is lettered accordingly in fig. 282, Cpc, and in proceeding soon receives at its inner surface an accession of fibres, a, coming down from the aorta. This band, Cpca, in winding spirally from left to right round the left ventricle along its middle third, gradually approaches both the base and the surface : for VOL. II. when it arrives at the anterior edge of the sep- tum it becomes the basial band, and having been traced round the left under the right ven- tricle, in making its second circle it passes over that cavity. Injig. 281 the commencement of its second course is exhibited. It is bisected, one portion, Cpcaa, being held up by a probe ; the other, at the anterior coronary track, act, receives at its inner surface a fasciculus of fibres, a, from the aorta, aa, and is also lettered Cpcaa. This fasciculus and por- tion of the band form together a groove, by winding over the pulmonary channel when brought down into its place, and which toge- ther form the basial part of the anterior boun- dary of this cavity. This band in its progress round this ventricle constitutes the basial band of the middle layer of its proper wall, and forms so many connexions with the base, that to trace them all would be found a very com- plicated piece of dissection ; it is, therefore, deemed better to give a general description of them. For instance, the aorta presents three different aspects under -which this band is con- nected to it: the first, at the termination of the anterior coronary track ; the second, between the pulmonary artery and the annulus venosus ; and the third, between the annulus venosus and the annulus arteriosus, or at the extremity of the posterior coronary track. The aorta re- ceives at each of these parts an insertion of fibres from the outer surface of the band ; and the band receives on its inner surface a fasci- culus from the aorta. These reciprocal com- munications occasion the band to be very firmly bound down to the base, and to be arranged, to a certain extent, into festoons. For each of these accessions from the aorta, an addi- tional a is added to the lettering of the band, which is, accordingly, designated Cpca a a a. As the band passes the annulus venosus, its outer fibres by a gentle obliquity in their course successively arrive at its tendinous margin, into which they become inserted immediately below those of the superficial layer, and some proceeding still more deeply pass under the tendinous margin into the ven- tricle, and form the musculi pectinati. In order to avoid repetition it may be here remarked, that this part of the description ap- plies to the annulus arteriosus also. The last two accessions of fibres this band receives should be traced, since they assist in the con- struction of the posterior boundary of the right ventricle. In fig. 282 this band is seen in the latter part of its course round the right ventri- cle, marked Citaaa; on reaching the pos- terior coronary track, pet, it is joined on its inner surface by two fasciculi which bind it down to the base, but on each side of this track it is separated and raised. One of these fasciculi, the last derived from the aorta, is not seen in this figure ; the other appears emer- ging from under this ventricle, being portion 2 of the middle layer of the septum, which disconnected itself from this band, Cpc, in its first circle round the left ventricle ; it is marked C large, being derived from the middle mass of fibres, cue, in fig. 278, in which 2 T 62G FIBRES OF THE HEART. portion 2 is seen crossing over to join the band CpcaaaaC, just before it becomes the rope ; the fasciculus of fibres a from the aorta a a is also seen joining this band at its inner sur- face nearer the base. By the union of these two fasciculi with the band in question, the basial half of the posterior boundary of the right ventricle is formed. By pursuing, in fig. 282, this band or combination of fibres, lettered CpcaaaaC, it is seen to form, while it is gradually twisting upon itself, the brim of the left ventricle, and then to make a sharp twist of its fibres into the rope R R, by which means they are rendered the internal fibres of the left ventricle ; in fig. 280 they may be traced expanding- again into a layer, pursuing the same spiral sweep from left to right, but from the base towards the apex, and inwardly instead of outwardly. Thus the de- monstration brings us back to our starting-point. We have yet to trace the shorter of the two bands which originate in the splitting of the middle mass of fibres, cue, in fig. 278, to embrace the right ventricle. This view ex- hibits only the inner fibres of this mass as they are prolonged into the inner or longer of the two bands; but fig. 281 affords an outer view of this mass of fibres as they are prolonged into the outer or shorter band. They are seen winding spirally up from the apex marked crc, and at the anterior coronary track, act, they split, in the form of a band, from the general mass to pass over the lower half of the cavity of the right ventricle. In this figure this band is separated and left extended, in order that the accessions of fibres it receives from the right surface of the septum may be seen, which are the fibres a from the aorta aa, and the fibres c and c form two of the carneee columns (not in view) passing obliquely down from right to left to the anterior edge of the septum, from which they extend into the band which is lettered Cacc, and unite in- timately with its fibres. When the band is replaced in its course over the ventricle, its accessory fibres are made to reflect at an acute angle upon themselves, and thus form the apicial part of its anterior boundary. This band describes one spiral circle round the heart, arriving again at the anterior coronary track at its basial extremity; it is inserted into the aorta, and if the fibres make a very oblique approach to the base, they will be also inserted into the tendinous margin of the annulus arte- riosus. The continuation of this band round the posterior side of the heart can be traced in fig. 279. Its width is equal to about a third of the heart's axis ; it is seen marked Cacc in its spiral ascent from left to right, passing, first, a little below the middle third of the heart; at the posterior coronary track, pet, becom- ing the middle third, and afterwards approach- ing gradually the base m its way to its points of insertion before-mentioned. As the tracing the fibres from the circum- ference to the centre, and from the centre to the circumference, is a matter of much difficulty, and as the description has been attended with much detail, it is desirable that a more general and concise view by means of a diagram should be afforded of the courses which the fibres take in constructing this organ. Recapitulation. (Vid. the diagram fig. 283.) We commence tracing the fibres of the heart from its very centre. The fibres, cc, from the two carneas columnae of the left ventricle, lv, are joined by the fibres, r, from the rope RR, after those fibres of the rope have expanded and formed the internal layer of the septum S ; in winding round the axis of this cavity they blend together as the initial letters crc indi- cate. The inmost of these fibres descend as far as the apex, where they twist sharply round and close the cavity, by which means they construct the apex, and become the superficial fibres of the heart. But the chief bulk of this mass of blended fibres makes a spiral sweep from left to right round the axis above the apex ; and when it has described two circles, crc, it splits at the anterior edge of the septum into two bands, one being considerably longer than the other. The longer first makes one circle round the left ventricle, then another, enclosing both ventri- cles. In making the first circle it passes through the septum forming its middle layer, and on reaching its posterior edge itreceives from the pulmonary artery accessory fibres, which have crossed over the cavity of the right ven- tricle, forming the inmost layer of its right or proper wall, and fibres from one of the carnese columnae of this ventricle, and from the aorta, being marked Cpca. The accessory fibres are not represented, as they would have ren- dered the diagram complicated and unintelligi- ble ; but they are indicated by their initials being added in the lettering of the bands. This band in question may now be traced round the middle third of the left ventricle advancing towards both the base and the outer surface of the heart; on completing its first Fig. 283. FIBRES OF THE HEART. 627 circle it arrives again at the anterior edge of the septum, receives another fasciculus of fibres from the aorta, and is marked Cpcaa. It is then seen to take its course round the base and in front of the right ventricle. As it passes by the right aspect of the aorta,it again receives from it a fasciculus of fibres, and is lettered Cpcaaa ; on reaching the posterior edge of the septum, it is further augmented by two accessions of fibres, one from the aorta at its posterior aspect, and the other from the middle layer of the septum. This combination of fibres from various sources is indicated by the combination of their initial letters, CpcaaaaC. It should be borne in mind that C large is the synalepha of crc— the initials of the primitive mass of blended fibres. This band, in passing along the base of the left ventricle, makes at first a gentle twist of its fibres form- ing the brim of this chamber; it afterwards makes a sharp twist and assumes the form of a rope, by which means its fibres are transferred to the interior of the ventricle. In descending this chamber, they expand again into a layer, and wind spirally round its cavity, first forming the internal layer, R, of the septum, and then associating with the expanded fibres of the two carneae columnae, and thus arrive at the points from which we commenced tracing them. We now return to the anterior edge of the septum, S, in order to trace the shorter band. At this part the primitive mass of blended fibres splits into two bands : the longer passes behind the right ventricle through the septum as already described ; the shorter passes in front. The shorter first receives a considerable accession of fibres from the right surface of the septum, which pass down from the aorta, and from the two Games columns springing from this sur- face : it is lettered Cacc ; it describes one spiral circle round both ventricles. It first passes over the lower half of the right ventri- cle, forming the apicial band of the middle layer of its proper wall, and then round the left ventricle in an oblique direction to the base, and terminates at the aorta near the anterior coronary track, having completed its spiral circle round the heart. As the demonstration has, in reference to the construction of the septum and of the right ventricle, been unavoidably disconnected, it is requisite to give a more systematic and com- prehensive description of their particular for- mation. The septum is composed of three layers : a left, a middle, and a right layer. The two former properly belong to the left ventricle ; and the last or right layer exclusively pertains to the right ventricle. The two former are composed of the primitive mass of fibres de- rived from the rope and the carnece columns? of the left ventricle ; the left layer being formed of the expanded fibres, R, of the rope, Rii,^g.280, in their first sweep round the cavity ; and the middle layer of the continued fibres of the rope in its second sweep, blended with the ex- panded fibres of the two carneae columnae. These blended fibres form the extended layer crc ; its cut edge a applies itself to the cut edge b, evidently forming the middle layer of the septum. The last or right layer of the septum has not the same origins as the two former have. Its fibres arise from the root and lower margin of the valve of that section of the aorta which pertains to the right ven- tricle, from that part of the root of the pulmo- nary artery contiguous to the aorta, and from the carneae columnae of the right surface of the septum. The fibres attached to the aorta and pulmonary artery may be seen in fig. 278, lettered a and r respectively, and in Jig. 280 the fibres from the aorta blended with those of the car- neae columnae are exhibited marked acc, forming the right layer of the septum. The right ventricle. — Although the right layer of the septum belongs anatomically to the right ventricle, yet when functionally considered it pertains, as well as the other layers, entirely to the left. For the concavity of this layer is, like that of the other layers of the septum, to- wards the cavity of the left ventricle, and therefore during the systole approaches the axis of this cavity, while it recedes from that of the right ventricle ; thereby assisting in the propul- sion of the blood from the former, and to a limited extent counteracting the propulsive effort of the latter ventricle. The right ventricle has, therefore, but one proper wall, which is connected to the left ventricle in a manner to be described hereafter. The right chamber should be divided into three channels : the auricular, the pulmonary or ventricular, and the apicial. The auricular is that which receives the blood directly from the right auricle ; the pulmonary is that formed by the fibres which arise from the root of the pulmonary artery at its entire circumference : in Jig. 278, the pulmonary artery, pp, and the fibres, p, are seen turned a little upon their axis, by which means the fibres are rendered oblique, and the channel the more complete ; and the apicial channel is that which forms the channel of communication between the other two, and which extends to the apex. The pro- per wall is considered as having three layers, the superficial, middle, and internal, although they cannot always be detached from each other. The superficial is composed of the mere superficial fibres of this wall, having the same origins and terminations as have its sub- jacent fibres; it forms the left wing Cacc of Jig. 279, and may be seen in Jig. 281, raised from the right ventricle and reflected over the base marked Cacc The middle layer is composed of two bands, the apicial and the basial. The apicial is formed of the first semi- circular portion of the shorter band of the heart, and passes over the lower half or apicial channel of this chamber ; it lies separated and extended over the apex of Jig. 281, marked Cacc The basial bind of this layer is formed of the first semicircular portion of the longer band as it makes its second circle round the heart. It is bisected and separated as seen at Cpcaa, of Jig. 281; in its natural situation it passes over the pulmonary and auricular channels of this ventricle, and is closely connected to the base. The internal 2 t 2 628 FIBRES OF THE HEART. layer arises chiefly from the pulmonary artery, PP ; it first forms the pulmonary channel, p, and then expands into a layer which crosses obliquely over the apicial channel, associated with fibres derived from one of the carnea? columns. The basial portion of this layer which crosses over the auricular channel, can- not often be separated from the fibres of its superjacent band, the fibres of the musculi pectinati being intricately interwoven with them. When this layer is replaced, its lower loose edge applies itself to the anterior boun- dary, a b, of this cavity, and is lined with its internal proper membrane. Of the three layers composing the proper wall of this ventricle, two, the middle and inner layers/, are confined at the edge of the septum, forming thereby the lateral boundary of this cavity. The boundary of the right ventricle. — It is true that every part of the internal surface of this chamber contributes in forming its boundary. But, as this cavity is formed chiefly by the splitting of the mass of fibres into layers and by their re-union, it is clear that unless the layers so separated were well secured at their points of junction, their separation would pro- gressively increase, and the cavity enlarge to a fatal extent by the repeated dilatations to which it is subjected. The mode of union which secures this lateral boundary merits therefore particular notice. As the lateral boundary corresponds to the edge of the septum, it admits of the same division into anterior and posterior. The anterior boundary being formed by the splitting of the layers, and the posterior by their re-union, their respective modes of construction are not precisely similar. The anterior boun- dary is principally formed by a certain set of fibres winding and reflecting upon themselves, as shewn in fig. 281. The basial part of this boundary, a b, is formed of fibres a, from the aorta a a, winding over the pulmonary channel of fibres p, in contributing to form the band Cpcaa. The fibres of this channel also con- tribute to form this part of the boundary, as is represented in fig. 278. The apicial part of this boundary is obviously constructed by the fibres acc which form the right layer of the septum being prolonged into the extended band, which on being replaced occasions them to be doubled upon themselves in passing over the apicial channel in association with the fibres of this band. The posterior boundary is constructed by the re-union of the fibres which pass in front of the cavity with others which pass behind it, and by the attachment of some of the fibres at the base to the aorta. The basial half of this boundary being formed by the conjunction of the under fibres of the basial band Cpcaaa, fig. 282, with a fasciculus of fibres, c, emerging from the middle layer of the septum, and with another fasciculus of fibres, a, jig. 278, arising from the aorta, aa. That part of the boundary contiguous to the base is greatly strengthened by the outer fibres of the basial band being attached to the aorta at its posterior aspect. And the apicial half of the posterior boundary being formed by the conjunction of the prin- cipal part of the internal layers of fibres which cross obliquely the cavity of the right ventricle with the chief part of the fibres of the middle layer of the septum as they emerge at its pos- terior edge, where they freely decussate. In fig. 281 the internal layer of fibres, pc, is seen crossing the cavity obliquely towards the apicial part of the posterior boundary, and in fig. 282 their conjunction with the fibres which emerge from the septum is seen forming a firm union. But the lateral boundary is rendered doubly secure by the curious circumstance of the coronary vessels, deeply penetrating the sub- stance of the heart along the entire edge of the septum, stitching down, as it were, just on the outside of the boundary, all the fibres which form it. The conical form of the heart. — The only point now remaining for consideration is the conical form of the heart. This form admits of the following explanation. Along the central cavity of the left ventricle are placed the two carneee columnar, the length of which is equal to the lower three-fourths of the length of the axis of this cavity. The fibres of these two bodies radiate, as represented in fig. 278 ; and the radiated fibres wind round the axis closely upon them, as is seen in fig. 280. By this radiation, instead of all the fibres passing longitudinally, which would have preserved these bodies in a state of equal thickness throughout their length, they are progressively parting with their fibres, retaining but a few, which, by their longitudinal course, reach the apex ; consequently these columns gradually diminish, becoming pyramidal, and forming together an inverted cone ; and as the fibres in well-formed hearts wind closely round these columns, the entire ventricle gently assumes the form of a cone. And although the right ventricle is, as it were, appended to the left, yet it is not so connected to it as to destroy the conical form, but, on the contrary, in such a manner as to form a concave parabolic section of a cone which adapts itself to the gentle cone of the left ventricle. The two ventricles thus united assume the form of the more rapid cone of the heart. Construction of the auricles. — For the pur- pose of ascertaining the mode in which the fibres form the auricles, large hearts, as those of bullocks and horses, should be selected. Not- withstanding the muscularity of the auricles is very much greater in large than in small hearts, yet the plan is the same in both, although less developed in the latter. The fibres of the auricles arise chiefly from the tendinous margins of the annulus venosus and annulus arteriosus ; they ascend interiorly, and arrange themselves into several columns, which give off branches. Some of the branches form a simple communication between two of the trunk-columns, but most of them subramify, by which means the interstices are filled in. In small hearts the columns are not only more slender, but more numerous and in- terlaced ; in these, the interstices in many places are not filled in, the internal and external proper membranes being in contact, and thus FIBRES OL' THE HEART. 629 com pleting the wall. Fig. 284 affords an interior view of a section of the right auricle, in which, Fig. 284. the lining membrane being removed, the fibres are seen arising from the tendinous margin of the annulus venosu3 av, forming the internal part of the wall of this auricle, and in their progress up arranged into columns, c, the branches of which are entwined together so as to construct the appendix. These convo- luted columns at the posterior aspect of the appendices are flattened, as shown in fig. 285, c, where their fibres are associating together, and Fig. 285. in passing round the edges to the anterior sur- face becomeevenly arranged again, as seen in the appendix a of the right auricle, ra, oifig. 286. Thus far the construction of the two auricles Fig. 286. CS D CI agrees, the fibres of each arising from its respec- tive annulus, forming first the inner part of the wall of the auricle, and then being arranged into columns which entwine together, forming the whole of the appendix. The fibres of the right auricle, after having formed the wall of this cavity, are prolonged to form the outer part of the wall of the left auricle. As may be seen in Jig. 286, the fibres which extend from the con- voluted fibres of the posterior surface of the right auricle, ra, wind evenly arranged, some over the apex, and others round the auricle, marked c, completing the outer part of the wall of the entire auricle : they then meet at the septum S, across which they pass associated together, marked d, and on reaching the left auricle divide into an upper portion and an anterior and posterior band. The tipper portion is composed of the continued fibres d, which proceed up the appendix and encircle its apex. The anterior band e winds round the left au- ricle la, and on reaching the root of the aorta k, its fibres become more or less at- tached to it in different hearts ; in its course upwards, marked f, when it has completed a circle it passes behind the fibres which form the first part of the circle to enter into the formation of the fleshy columns of the appendix. The posterior band passes over the left auricle be- tween the appendix a and the vena cava su- perior cs; and in fig. 285 it can be traced, coming over, marked g, and passing along the posterior surface of this auricle la, including in its course the posterior edge of the appendix a ; the fibres which pass along the posterior edge of the appendix, on arriving at the ante- rior edge, separate from the band g to pursue their course round the edge of the appendix, — now along the anterior edge, — and join the fibres d, which cap the apex. This division of the band which encircles the appendix is con- stant, and evidently affords particular strength to its edge. The band itself g winds down towards the base, expanding and surrounding the orifices of the pulmonary veins p; some of its fibres become lost on the surface of the auricle, and the others may be traced to the root of the aorta. This band cannot be completely detached in consequence of some of its fibres being inter- woven with its subjacent fibres. The left auricle, without the addition of these bands, would nearly balance in substance and strength the right ; their addition gives, there- fore, to the left a considerable preponderance in these respects over the right auricle. The septum S is, mfig. 286, shown to^be com- posed, superiorly, of the transverse band of fibres d, which passes from the right to the left auricle ; in its middle part, of the ascending fibres H, which arise from the root of the aorta k, and pass up behind the band d, some joining this band, the others proceeding to the vena cava superior cs ; and lastly, at the infe- rior and posterior part, of a slender fasciculus of fibres which crosses the septum transversely between the root of the aorta k and the vena cava inferior ci, extending from the annulus venosus to the left auricle, but which cannot be seen in this figure. In concluding these remarks on the construc- tion of the auricles, it may be mentioned that in theheartsof large animals a great difference ex- ists in the structure of the two vena? cava?, the superiorbeingparticularly fleshy,and the inferior apparently devoid of muscularity. (H. Scarle.) 630 ABNORMAL CONDITIONS OF THE HEART. HEART, ABNORMAL CONDITIONS OF. — There is no organ in the body in which the various deviations from the normal state have been more diligently or more carefully explored than the heart ; nor ought it to be otherwise, when we take into account the important part which the heart performs in the organism, and the serious nature of the derangements which its diseases in general produce, — how many or- gans and how many functions are involved in the break-up which too often follows the oc- currence of morbid alterations of the heart. The great frequency* of diseases of this organ, and the manifest and tangible shape which these diseases assume, as well as the little liability of its component structures to those appearances which have been denominated pseudo-morbid, these circumstances render it comparatively easy to detect and observe its abnormal condi- tions. To one who has made the natural condition of the whole organ, as well as of its several parts, the subject of careful study, there is no field of investigation in morbid anatomy which presents fewer difficulties. The records of anatomy are not without in- stances of total absence of the central organ of circulation (acardia); and it may well be supposed that such cases would also afford examples of the defective development of other not less important organs. In short, it is in ace- phalous and anencephalous foetuses that the heart is most frequently wanting, although its ab- sence is not, as some observers suppose, a con- stant characteristic of these forms of monstro- sity ; nor on the other hand does acardia ne- cessarily imply acephalia or anencephalia. Thus in the case recorded by Marriguesf, and quoted at length in Breschet's Memoir Sur I'Ectopie (lit Caw,Jthe brain was present, while all the usual contents of the thorax were wanting, their place having been supplied by a large bladder full of clear water which occu- pied the whole thoracic cavity. The details of another case were communicated many years ago to the Royal Society by Sir Benjamin Brodie, and are published in the volume of their Transactions for 1809. The foetus was one of twins, as is most frequently the case when the heart is absent. The brain was " nearly the natural size, and nothing unusual was observed in it." The heart, thymus gland, and pleura were absent, and the lungs most imperfectly developed. The aorta, however, was tolerably perfectly developed, but as a con- tinuation of the umbilical artery extending from the left groin upwards on the fore-part of the spine to the upper part of the thorax, where it gave off the two subclavian, and afterwards divided into the two carotid arteries without forming an arch. The external and internal iliac arteries of the left side came from this artery in the left groin immediately after it left the umbilicus, and the common iliac of the * Out of 520 post-mortem inspections recorded by Dr. Clendinning, 170 were cases of diseased heart, or about 33 per cent. — Vide his Crooniaa Lectures for 1838, Med. Gazette, vol. xvi. p. 657. f Mem. de Mathem. pres. a l'Acad. des Sc. t. iv. £ Rep. Gen. d'Anat. et de Physiol, t. ii. right was given off from it in the lumbar region after it had gained the situation of the aorta. We shall first examine the congenital devia- tions from the normal state hi this organ, and secondly its morbid alterations. I. Congenital abnormal conditions. — These are observed under three heads. 1. Congeni- tal aberrations of position, or ectopia? of the heart. 2. Malformations by defect in deve- lopement. 3. Malformations by excess of de- velopement. 1. Congenital aberrations of position. — The simplest form of malposition is that in which the heart retains the vertical position which it occupies during the early periods of intra-ute- rine life ; but of this the authentic instances are rare.* Better known is that deviation in which the heart is directed downwards, forwards, and to the right side. This malposition generally occurs as a part of a universal transposition of the abdominal and thoracic viscera, of which many well-marked examples are now on re- cord ; however, it sometimes, although more rarely, exists alone without ectopia of any other organ. Breschetf records four cases of this latter kind. Otto} has met with three in- stances, and many other examples are scattered among the records of anatomists.§ In this form of transposition of the heart, the aorta sometimes passes down along the right side of the spine, and at other times down its left side. In the latter case the transposition is not so complete, the ventricles retaining their natural position with reference to the anterior and pos- terior aspects of the body. Again the heart may be pushed too much to the left side, as a mechanical result of congenital diaphragmatic hernia of the right side; and it has been found laid across in the chest from one side to the other, the apex being at one time directed to the right side, and at another to the left, or turned upside down, the base toward the abdomen, or in that cavity, the apex upwards still remaining in the thorax. In such cases as have been just detailed, the heart still retains its title to be considered as a thoracic viscus ; but other and more re- markable malpositions of it have been found, where it is excluded from that cavity. These are, in fact, congenital thoracic herniae in va- rious directions, of which Breschet, whose memoir already referred to contains the most complete account of this subject, enumerates three principal varieties, according to the situ- ation in which the heart is found, viz. the superior or cervical displacement, the abdo- minal or inferior, and the thoracic or anterior. Thus Breschet details a case in which the heart, lungs, and thymus gland were all con- tained in the anterior part of the neck, forming a large tumour under the lower jaw. The point of the heart was attached to the base of the tongue, and placed between two branches of the lower jaw. The thorax was occupied * Sandifort, Obs. Anat. Path, t Op. cit. f Selt. Beobacht. part i, p. 95, and part ii. p. 47. § Iieuss' Rcpertorium, vol. x. p. 90-91. ABNORMAL CONDITIONS OF THE HEART. 631 by the abdominal viscera, which had passed up through a fissure in the diaphragm. In a second instance of this high displacement the apex of the heart adhered to the palate; but in this case the malposition appears to have been owing to a morbid adhesion of the umbilical cord to the head, by which all the viscera were drawn out of their natural positions.^ A less degree of cervical displacement is where the heart is found immediately above the thorax, in the front of the neck, which, however, is very rare. When the malposited heart is found in the abdomen, the diaphragm is generally deficient to a greater or less extent. In a case narrated by Mr. Wilson,* the heart was in a fissure on the convex surface of the liver — the infant lived seven days ! Ramel also gives an instance of the heart being placed in the region of the stomach, and the indi- vidual in whom he observed it was ten years of age. And in the extraordinary case related by Deschamps, the heart occupied the place of the left kidney ! Not the least marvellous cir- cumstance about this case is, that the indi- vidual was an old soldier, who had served several campaigns, and enjoyed excellent health, with the exception of nephritic pains, which ultimately procured him his discharge from the service. The right kidney alone existed, and was found in a state of suppuration. f The vessels emanating from the heart passed through an opening in the diaphragm into the thorax. Dr. Paget mentions some instances of vari- eties of position which parts of the heart may assume with respect to each other. In a case recorded in the first volume of the Edinburgh Medico-ChirurgicalTransactions by Dr. Holmes of Canada, the right auricle, enlarged to the capacity of a pint, was found to open into the left ventricle in place of the right, into which, however, the blood afterwards found its way through a small perforation in the septum of the ventricles. The aorta and pulmonary artery may arise from one ventricle alone, either right or left, and instances of each preternatural origin are pre- served in the museum of the Edinburgh Col- lege of Surgeons. When the anterior wall of the thorax is de- ficient, the heart may be found protruding through the opening, as in fissure of the ster- num, or a defect in its inferior portion as well as in some of the ribs; nor does this mal- position necessarily destroy life. Where the deficiency is not confined to the wall of the thorax, but also extends to the abdomen, the stomach, liver, and spleen, with the heart, are found occupying a large hernial sac in front of the opening, which is sometimes contained in the sheath of the umbilical cord, or covered by an extension of the . common integument. In the case of simple fissure of the sternum, it has occurred that the heart had not protruded, but occupied its natural position, being simply * Phil. Trans. 1798. t Quoted by Breschct from the Journ. Gen. de Med. t. xxvi. exposed to view by the abnormal opening in the chest.* 2. Malformations by defect in development. — Our limits compel us to restrict the present account to little more than an enumeration of the congenital malformations which may be placed in this class. In these malformations we find a diminution in the normal number of the heart's cavities, either from a very early arrest in the developement of the whole organ, or from a total non-developement of the sep- tum, or from its imperfect developement. A few rare instances, many of which have oc- curred in the lower quadrupeds, of an ex- tremely imperfect state of the heart, are quoted by Otto, in which that organ seemed to consist of nothing but a fleshy enlargement at the commencement of the aorta, described as " a mere fleshy mass without any cavity," or " a longish solid mass from which the vessels arise," " or a mere expanded vascular trunk." The dicalious heart of Hunter, or that with two cavities, exists at a very early period of the developement of the Mammiferous embryo: it is described and figured by Baer in the em- bryo of a dog, of three weeks, only four lines in length, as consisting of a single auricle and a single ventricle.f The permanence of this state of the heart, similar to the natural con- dition of that organ in fishes, constitutes one of the simplest but rarest malformations in the human subject. From the ventricle a single vessel arises which subdivides into the aorta and pulmonary artery. A very perfect example of this malformation is described by Mr. Wilson in the Philosophical Transactions for 1798; it is the same case which has been already al- luded to as affording an instance of malposition. In this case the blood was returned from the lungs by two veins which joined the superior vena cava, and entered the auricle along with it, the inferior cava being formed in the usual way. Other examples are recorded by Mr. Slandert,J Dr. Farre,§ Professor Mayer,[| and Dr. Ramsbotham.^f H The heart with three parities (tricoilia of Hunter), that is, containing two auricles and one ventricle, or that form of the heart which belongs to the Batracbian reptiles, must be very rare, if indeed it ever occurs. A case is related by Breschet,** in which a * The reader who desires farther information on the congenital ectopia of the heart, may consult Breschet's memoir already referred to; Dr. Paget's Inaugural Dissertation on Malformations of the Heart, Ed. 1831 ; the article on Displacement of the Heart, by my valued friend Dr. Townsend, in the Cyclopedia of Practical Medicine, vol. ii.; Fleischman de vitiis congen. circa thoracem et abdomen, Erlang. 1810; YVeese de Ectopia Cordis, Bcrol. 1819 ; and Haan de Ectopia Cordis, Bonn. 1825. t De ovi Mammal, et Hominis Genesi ; also in Forbes' Journal another case by Baer, vol. i. plate 2, fig. 9, human embryo about the fifth week. X Phil. Trans. 1805. $ On the Malformations of the Human Heart. Arch. Gen.de Med. torn. xvii. 1 Lond. Med. and Phys. Journal. ** Rep. Gen. d'Anat. torn. ii. 632 ABNORMAL CONDITIONS OF THE HEART. single ventricle and two auricles existed, but along with an imperfect inter-auricular septum. The two auricles, therefore, virtually formed one cavity. A similar case is recorded by Wolff,* and is remarkable from the fact that the individual in whom it was observed lived to the age of twenty-two. These hearts then do not exactly correspond to the tripartite heart of Batrachia, inasmuch as the two auricles communicate. A similar case, shewn by Mr. Lawrence to Dr. Farre,t explains more par- ticularly the true nature of the malformation. It was a deficiency of the septa, both auricular and ventricular, the latter having been alto- gether wanting ; the former consisting only of a small muscular band, which left a large fora- men ovale without a valve, but the vence cavae and pulmonary veins opened into their respec- tive auricles, which externally appeared to be quite separate. The ventricle communicated with the two auricles by a single ostium ventriculi, and the aorta and pulmonary artery, the en- trance of the latter being somewhat contracted, arose side by side from the left part of the ventricle. Most of the other defective malformations of the heart consist in preternatural communica- tion between the right and left cavities, resulting from various causes. 1, The communication is direct,eitherfromanopen foramen ovale, orfrom an imperfection in the septum of the auricles or of the ventricles, or from the co-existence of all three or any two of them. 2. The com- munication is indirect, the septa being perfect, but the ductus arteriosus remaining pervious. The open foramen ovale is by far the most common of all the malformations of the heart; numerous examples of it are now on record, as found in persons of all ages. The opening of communication varies considerably as to size, apparently according to the period of develope- ment at which the arrest took place ; the di- ameter of the opening ranges between two and twelve lines. We know that the size of this orifice is inversely as the size of the foetus during intra-uterine life, whence we may infer that the larger the opening is, the earlier must have been the period at which further deve- lopement ceased. In many instances the valve- like portions which bound this opening have acquired their full developement, and the only defect seems to be the non-adhesion of their margins, so as to close the cavity ; this non- adhesion again may involve the whole extent of the margins of the valves, or only a very small portion, thus leaving a large or small opening of communication between the two auricles. Such a condition of the inter-auri- cular septum does not necessarily occasion that intermixture of the blood which so com- monly accompanies the communication be- tween the right and left cavities ; and where the opening is small, of course this inter- mixture is the less likely to occur. Thus every anatomist must be aware that it is not an un- frequent occurrence to find an opening large * In Kreysig's die Krankeit. Herz. B. iii. t Loc. cit. p. 30. enough to introduce a goose-quill in the hearts of adults who during life exhibited no derange- ment of the circulation, and who died of dis^ eases totally unconnected with the heart. On the other hand we are often surprised at the amazing size of the opening in the hearts of persons who have lived many years, and have shewn less disturbance of functions than the freedom of the communications between the auricles would warrant us to expect. In many of these cases the absence or mildness of sym- ptoms may be accounted for by the obliquity of the passage of communication, and the overlapping of the margins of the valves, so that at times they completely oppose the flow of the blood from one side of the heart to the other, whilst at other times the passage is left more or less free. In a heart which I lately saw in the Museum of Guy's Hospital/the circumfe- rence of the open foramen ovale was equal to that of a halfpenny, (i- e. about an inch in diameter,) and yet the patient had lived to the adult period; and in a case quoted by Dr. Farre from Corvisart, the foramen ovale was " more than one inch in diameter." Such cases strongly favour the opinion that the foramen undergoes considerable enlargement when once all impediment to the passage of the current of blood from one side to the other has been removed.* More rarely we find the fossa ovalis cribriform, and thus several small open- ings of communication exist between the auricles, and sometimes in addition to the un- closed foramen ovale, we have a true imper- fection in the septum, as in the case related by Walter,t and another by Otto.J Imperfection in the septum ventriculorum is a much less frequent cause of the communi- cation between the right and left hearts than the open foramen ovale. The opening, varying in diameter from two lines to about an inch, is situated towards the base of the septum, so that the ventricles communicate at their bases; a fact which evidently indicates that the opening results from the progress of the de- velopement of the septum being arrested near its completion, since the base of the septum is the last portion formed. The orifice of com- munication generally opens upwards towards the orifices of both arteries, and is bounded inferiorly by the rounded smooth edge of the ventricular septum. In these cases the aorta opens into both ventricles and appears to arise from both ; and frequently the orifice of the pulmonary artery is contracted and more rarely obliterated, either from non-developement or from previous morbid action ; moreover, ap- * It is not, perhaps, correct to suppose every case of open foramen ovale congenital ; at least it is certain that many patients date their symptoms from a fall or blow ; and even without any evi- dence of the occurrence of such violence many cases have been observed which can be explained only by supposing that the forameaovale had been morbidly re-opened. See A bemethy in Phil. Trans. 1798 ; Otto, Selt. Beobachtungen ; and Pasqualini, Memorie sulla frequente apertura del foramine ovale rinvenuta nei cadaveri dei tisici. Rom. 1827. t Observat. Anatom. i Palhol. Anat. by South. ABNORMAL CONDITIONS OF THE HEART. 633 parenfly as a consequence of this contracted state of the arterial outlet of the right ventricle the ductus arteriosus often remains open, which, by its communication with the aorta, conveys some blood into the pulmonary arteries from that vessel ; and, as a further complication, the right ventricle is very small and appears merely as an appendage to the left ; sometimes also the left auricle is very small, while the right is much dilated. Where so much complication exists, as that just detailed, one is only surprised that vitality can be at all supported after extra-uterine life has commenced ; yet we find that children with hearts so malformed live three, four, or five days, and even as many weeks or months; but where the perforation of the septum is not accompanied with the contracted state of the pulmonary artery, life may be prolonged to a considerable period. Thus, Louis quotes one case of a general officer (age not stated), whose death was occasioned by the active part he took in the American war. Along with ossified valves of the right auriculo-ventricular orifice, there existed a perforation of the septum ven- triculorum large enough to admit the extremity of the little finger. In another case, quoted from Richerand, the patient aged 40, the per- foration of the septum was half an inch in diameter. We say that the two sides of the heart com- municate indirectly when the ductus arteriosus continues, as in its foetal state, to convey the blood of the right heart into the aorta descen- dens, where it becomes intermixed with the blood of the left heart. But it is very rare to find this condition existing alone, and when it does so exist, the canal of communication is generally very narrow. More frequently it is complicated with a contracted state of the pul- monary artery, the place of which it seems to supply. In a case related by Mr. Howship,* this vessel constituted, in fact, the trunk of the pulmonary artery. The pulmonary artery proper arose in its usual situation, but was quite impervious at its root, though far beyond, and terminated in a cul-de-sac beside the heart. Similar cases are recorded by Dr. Farre. At other times the ductus arteriosus is emploved to supply the place of the aorta descendens; the aorta is perfect only as far as the termination of its arch, where it contracts, and its con- tinuation is formed by the ductus arteriosus, through which the descending aorta receives its whole supply of blood.f A very perfect case of this kind is quoted by Dr. PagetJ from Steidele. The aorta and pulmonary artery arose as usual ; the aorta was entirely distributed to the head and upper extremities, while the pulmonary artery, after giving off two branches to the lungs, con- tinued as the aorta descendens without any communication with the aorta ascendcns. Malformations of the valves. — A not un- important class of defective malformations in * Edin. Med. and Surg. Jcu-n. vol. ix. t See Sir A. Cooper's cases in Farre, loc. cit. X Loc. cit. the heart consists of imperfections in the num- ber or structure of the valves. The aorta may have two valves only, one of which may retain its natural form and size, while the other pre- sents the appearance of having been formed by the fusion of two valves ; it may therefore present one or more openings in it, so as to appear somewhat cribriform. A similar con- dition is met with in the pulmonary artery, when sometimes the three valves seem as it were united to form one membrane, which like a diaphragm stretches across the mouth of the artery, and is perforated in the centre by an opening through which the blood finds its way into the artery. This narrowing of the orifice of the pulmonary artery is the most frequent of the congenital malformations of the valves : we have already described it as a frequent con- comitant of imperfect septum of the ventricles. Congenital imperfections of the mitral and tricuspid valves are of very rare occurrence. The perforated or cribriform condition which is frequently seen affecting these valves, the Eustachian and Thebesian valves, and more rarely the semilunar valves, is probably the result of a morbid atrophy. Congenital absence of the pericardium. — Connected with the malformations by defect of developement we may mention the con- genital absence of the pericardium, which, although very rare, rests on too strong evidence to admit any further doubt of the possibility of its occurrence. Most of the cases related by the older authors weie in connexion with displacement of the heart, and from the liabi- lity of mistaking universal adhesion of the pericardium for this congenital absence, many anatomists, among whom was Haller, denied that such a defect had ever existed. Dr. Baillie* was the first of modern anato- mists who accurately described a case of this kind. " Upon opening," he says, " into the cavity of the chest, in a man about forty years of age, in order to explain at lecture the situation of the thoracic viscera, I was ex- ceedingly surprised to see the naked heart lying on the left side of the chest, and could scarcely at first believe what I saw, but the circumstances were too strong to keep me long in doubt. The heart was as bare and distinct as it commonly appears in opening into the cavity of the pericardium, and every collateral circumstance confirmed the fact The heart lay loose in the left cavity of the chest, unconnected in any way except by its vessels ; was of a large size, elongated in its shape, and had its apex opposite to the eighth rib. The right auricle was obviously in view in the same manner as when the pericardium has been opened, and the vena cava superior and inferior were clearly observed entering into it. The appendage of the left auricle w as as clearly in view ; and when the heart was inverted, so as to have its apex turned upwards, the extent of its cavity was seen with the two pulmonary * On the want of a pericardium in the human body, in Transactions of a Society for the Improvement of Med. and Chir. Knowledge, vol. i. p. 91, with a plate of the appearances. 634 ABNORMAL CONDITIONS OF THE HEART. veins of the left side entering behind the ap- pendage. The right and left ventricles were distinct, with the coronary vessels running upon them ; and the aorta and pulmonary artery were seen clearly emerging from them." There is nothing in Dr. Baillie's description to indicate positively whether the visceral layer of the serous pericardium was absent or not, although we may infer its absence ; what he says bearing upon this subject is as follows : " The heart was involved in the reflection of the pleura, belonging to the left side of the chest, which became its immediate covering, and upon making the slightest incision into the substance of the heart, its muscular structure was laid bare, as in any common heart de- prived of its pericardium." Breschet* has put on record a case in which the pericardium was absent, not altogether, but in greatest part. The subject of it was a young man of twenty-eight years of age, who died in the Hotel Dieu of an inflammatory affection of the intestines. The heart lay free under the left lung without any external fibro- serous envelope. The mediastinum was formed only by a simple serous lamina belong- ing to the right pleura, and upon the left of this lay a rudimentary fibrous capsule, attached above to the origin of the great vessels. The serous membrane was altogether absent, but the heart was immediately inverted by a serous lamella, which was prolonged from the left pleura. In both this case and that of Baillie, the left phrenic nerve was displaced and brought towards the mesial line of the body, and not covered by the serous membrane, — an anato- mical character, which, as Breschet suggests, may serve to distinguish congenital absence of the pericardium from the simple adhesion of that membrane to the heart.f II. Malformatiom of the heart by excess of developenient. — Plurality of the heart itself may be obviously regarded as coming under this head; but I am not aware of any instance in which a double heart has been found in a perfect single foetus, nor can the possibility of such an occurrence be deemed admissible. It is in monsters formed by the junction of two that this double form of the heart has been met with. Thus, in one case referred to in Bouil- laud's work, all the upper parts of the foetus were double, while the inferior were simple. There were two heads, two necks, quite separate and of the ordinary size. The necks terminated in a single very wide thorax, to the upper part pf which and between the insertion of the two necks an arm was attached in the vertical direction, one perfectly formed arm being placed on each side of the thorax. There were four lungs, each having a distinct pleura, but only one diaphragm : there were also two hearts and two pericardia, each of which had two vena cavae and a pulmonary artery, four pulmonary veins and an aorta. The two aortse * Mem. sur uu vice de conformation congenitale des enveloppes du cceur : Rep. Gen. d'Anat. t. i. p. 212. f See references to other cases in Otto's Path. Anat. by South, p. 254. united at the lower part of the dorsal region of the spine, and formed the artery by which the abdominal viscera and lower extremities were supplied. The evidence respecting the occurrence of an increase in the number of the parts of the heart is very unsatisfactory. The often quoted case of Kerkring,* with a double right ven- tricle ; one by Vetter,f with four auricles and four ventricles, quoted by Otto ; a third byChe- mineau,J with three ventricles, are, if genuine, the most remarkable instances on record, be- sides various instances in the lower animals, especially birds. Andral states that he has seen a heart with three auricles, and another with four ventricles : it is much to be regretted that he has given no description of these sin- gular malformations § Supernumerary cavities, or septa dividing the primitive cavities of the heart, are the most common instances of excessive developement. Adopting the arrangement of Andral, || we find — 1, a supernumerary cavity forming a sort of accidental appendage to one of the auricles or ventricles, and communicating with the cavity of the part to which it is attached : 2, a supernumerary septum, forming an im- perfect division of one of the natural cavities ; 3, a second cavity, completely partitioned off by one of these septa, and giving off super- numerary vessels, which communicate with the regular vessels of the heart. It appears to me, however, to be very questionable that all cases of supernumerary cavities are the result of ex- cessive development, but that, on the contrary, they are sometimes mechanically consequent upon defective formation in other parts. At least it is in this way that I account for the con- dition of the heart of a boy, aged ten years, which I examined several years ago, and which has been described by my respected friend, Dr. John Crampton, in the Transactions of the Dublin College of Physicians for 1830. In this heart there were three instances of defective developement — absence of the valves of the pulmonary artery, an open foramen, and an imperfect septum ventriculorum. Attached to the right ventricle there was a supernumerary cavity with which the pulmonary artery com- municated. This cavity communicated also with the right ventricle, by an opening large enough to admit the little finger, and formed under the columnse carnese of the ventricle. The pulmonary artery was not only destitute of valves, but at the usual situation of the valves its lining membrane was puckered, by which its orifice was manifestly contracted. The su- pernumerary cavity, in this instance, was in all probability occasioned by a partial dilatation of the infundibular portion of the right ventri- cle, in consequence of the obstruction at the pulmonary orifice. Increase in the number of the valves of the large arteries may be counted among the ab- * Spicil Anat. ohs. 69, p. 139. f Aphorism, aus der Pathol. Anat. f Hist, de l'Acad. des Sc. an. 1699. $ Path. Anat. by Townsend, vol. ii. p. 333. j| Loc. cit.j ABNORMAL CONDITIONS OF THE HEART. 635 normal formations by excess. Thus, four or even five valves are occasionally found in the pulmonary artery more frequently than in the aorta. The supernumerary valves are always small, and sometimes appear to have been formed at the expense of the next normal one. Anomalous connexion of the vessels of the heart. — Our space will only permit us to enumerate the principal observed varieties. 1. The aorta or pulmonary artery, or both, appear to arise equally from both ventricles, the septum of the ventricles being more or less deficient. 2. The aorta may arise from the right ventricle, and the pulmonary artery from the left, the veins preserving their natural posi- tion. 3. The vena azygos opens into the right auricle. 4. The hepatic veins open into the right auricle. 5. The ductus arteriosus opens into the right ventricle. 6. Two superior vena cava open into the right auricle. 7. Very rarely the right auricle gives insertion to one or more pulmonary veins, and on the other hand the left auricle receives sometimes the superior vena cava, and at other times the inferior. 8. Meckel states that he has seen the great coronary vein of the heart to open into the left ventricle.* Professor JefFray, of Glas- gow, relates a case in which the inferior cava opened into the upper part of the right auricle, taking the course as well as the place of the vena azygos. On displacement or ectopia of the heart as a consequence of disease. — The most common cause of morbid displacement of the heart is an effusion of air or liquid into one of the pleural cavities. The displacement is most manifest when it follows effusion into the left side, by which the heart is pushed over to the right, the degree of displacement depending on the amount of effusion, and thus alteration of the heart's position becomes one of the diagnostics of empyema, hydiolhorax, pneumo- thorax. In general, the more rapid the effusion the more certainly will the displacement be effected, and the greater will be its extent. In nine cases out of ten, as my friend Dr. Towns- end remarks,t when the heart is removed out of its natural situation, the displacement will be found to have arisen from empyema or pneumo- thorax ; and of twenty-seven cases observed by him, the heart was perceptibly displaced in every instance. On the other hand, when the effusion is slow and gradual, the extensibility of the neighbouring textures is more completely brought into play, and the displacement of the heart is thus counteracted, whence it happens that in cases of chronic dropsical effusions into the chest, displacement of the heart is not of frequent occurrence, nor is it extensive when it does take place. When the effusion occurs on the right side, the heart may be pushed more to the left, and upwards, than is natural, but to effect this a considerable effusion is necessary. The first notice of this fact is due to my able friend, Dr. Townsend, to whose article I have already referred. In a case of pneumothorax * This enumeration is taken from Bouillaud, Traite des Maladies du Cceur, t. ii. p. 588. t Cyclop. Pract. Med. vol. ii. p. 390. to which he refers, and which I also witnessed, the effusion was on the right side, and the heart was distinctly seen and felt pulsating between the fourth and fifth ribs, near the left axilla. After paracentesis, which was performed by the late Dr. M'Dowel, the heart gradually returned to its normal position, as the displacing force was removed by drawing off the air and fluid contained in the opposite pleura. More- over, as has recently been ascertained by Dr. Stokes, the absorption of an effusion of the right side will cause the heart to be displaced to that side, the pleural cavity being obliterated by lymph, while the lung of the left side is en- larged so as to aid in occupying the vacant space and pushing the heart over. It is scarcely necessary to observe that tu- mours forming in the right or left sac of the pleura may occasion displacement ; thus aneu- rismal tumours may push the heart to the right, to the left and upwards, or even forwards and outwards against the wall of the thorax, or downwards, so that its apex will pulsate in the epigastrium. Of this last displacement, Dr. Townsend* relates an example. I have my- self observed, some years ago, a case where the heart was pushed forwards and outwards, and as it were compressed against the ribs by an enormous aneurism of the thoracic aorta ; the sounds of the heart were so modified by this compression as to lead to the erroneous diagnosis of concentric hypertrophy. In the case recorded by Drs. Graves and Stokes,+ the heart was pushed upwards and to the right side by an abdominal aneurism, so as to pulsate in the in- tercostal space of the third and fourth ribs. Dr. Hope mentions the displacement to the left by an aneurism of the ascending aorta. Any cause which pushes the diaphragm upwards and prevents its descent, such as distension of the abdomen by an enlarged viscus, a tumour, or an effusion, will change the position of the heart, so that its axis will be directed horizon- tally ; and Dr. Hope has remarked that the same position may be produced by an adhesion of the pericardium to the heart, by which its enlargement downwards is prevented. A diaphragmatic hernia will displace the heart to an extent proportionate to that of the visceral protrusion. In a case recorded by Drs. Graves and Stokes, the stomach and a large portion of the transverse arch of the colon were lodged in the left cavity of the thorax, and pushed the heart and mediastinum towards the right side. When the lung is enlarged from dilated air-cells, the heart may be displaced : it may be drawn considerably downwards by the dia- phragm, which yields before the enlarged lung, thus increasing the vertical diameter of the chest ; or it may suffer a slight degree of lateral displacement, the mediastinum being pushed to the right side by the lung. J Dr. Stokes has related the remarkable, and so far as I know unique case of displacement, or as he terms it " dislocation," of the heart * Loc. cit. f Dub. Hosp. Rep. vol. v. p. 10. | See Dr. Stokes's valuable work on Diseases of the Chest, pp. 187-191. 636 ABNORMAL CONDITIONS OF THE HEART. from external violence. The patient was crushed between a water-wheel and the em- bankment on which the axle was supported. Several ribs were broken, as well as the right clavicle and humerus. The heart, which, ac- cording to the statement of the patient, had always occupied its natural situation, was now found beating at the right side.* MORBID ALTERATIONS OF THE MUSCULAR SUBSTANCE OF THE HEART. 1. Inflammation of the muscular structure of the heart, or carditis (the carditis proper of some pathologists). — The same anatomical characters which would lead us to pronounce any muscu- lar tissue in a state of acute inflammation, would justify a similar conclusion respecting the heart. But from the sparing deposition of cel- lular tissue around this organ and between its fibres, the anatomical phenomena which denote the previous existence of inflammation are not so marked in itasinthe muscles of animal life; and judging from the rarity of these organic signs, as well as from the unfrequent occurrence of those symptoms which so great a morbid process could scarcely fail to produce, we may reasonably conclude that active inflammation deeply im- plicating the carneous fibres of the heart, and originating in them, is very seldom met with. The anatomical characters indicative of car- ditis are a dark, almost black, colour of the muscular substance, the fibres of which have lost in a great measure their cohesive power; they are very compressible and readily torn, and consequently cannot be easily isolated to any great extent, although easily separable en masse. When the muscular wall of either ven- tricle is pressed, the blood oozes out from the divided vessels on the cut surface in much greater quantity than usual. In Mr. Stanley's case, as in all cases, the dark colour of the fibres " evidently depended on the nutrient vessels being loaded with venous blood." When in addition to these signs we find purulent de- posits in various parts of the muscular struc- ture, and moreover, when it is manifest that the internal and external membranes are implica- ted, from the effusion of coagulable lymph on them to a greater or less extent, no doubt can be entertained respecting the exact nature of the lesion. In Mr. Stanley's case, " upon looking to the cut surface exposed in the section of either ventricle, numerous small collections of dark-coloured pus were visible in distinct situations among the muscular fasciculi." + A similar case has been recorded by Dr. P. M. Latham, the anatomical characters of which ac- corded with those above mentioned. " The whole heart was found deeply tinged with dark- coloured blood, and its substance softened ; and here and there, upon the section of both ven- tricles, innumerable small points of pus oozed from among the muscular fibres." J Every anatomist must have noticed how variable is the colour and the consistence of the muscular structure of the heart, even indepen- * Med. Gazette, vol. viii. t Med. Chir. Trans, vol. vii. $ Med. Gazette, vol. iii. dent of disease of the lining tissues. The pale, soft, compressible, flexible, and, to use a com- mon word, flabby heart, strongly contrasts with the firm, plump, fresh-looking elastic one; in the former, the flaccid parietes fall together im- mediately the cavities are emptied ; in the lat- ter, the surfaces retain their convexity, although the contents of the cavities have been com- pletely removed. Between these two extremes there are various grades of colour and consis- tence, of which Bouillaud particularises three as being the result of inflammation, the red softening, the white or grey, and the yellow. The first is probably that which may be said unequivocally to follow primary inflammation of the muscular texture ; the other two, how- ever, as Bouillaud admits, occur most fre- quently in connection with pericarditis : they occur, too, as Dr. Copland observes, where no sign of inflammation is manifest, and where during life there had been no evidence of car- diac disease ; in cases of general cachexia and of constitutional disease, attended by discolora- tion of the surface of the body, arising, in fact, as Dr. Williams explains, from an altered state of the nutrition of the organ, owing perhaps to partial obstructions in the coronary vessels ra- ther than to the immediate influence of inflam- mation. This last excellent observer makes the following judicious remarks in reference to this matter.* " To judge that the tissue of the heart is especially diseased, we must see that it differs much in appearance from the other muscles of the same subject. You will find, on comparing the same muscles in different subjects, a remarkable variety of colour; and in some there is no freshness in any of the muscles, but all are pale, and verging on a pinkish drab or dingy brick colour." Perhaps the most correct arrangement of the various cir- cumstances under which softening of the heart may take place is that given by Andral. 1st, Softening connected with active hyperemia of the heart ; 2d, softening connected with anremia of the heart ; 3d, softening connected with atrophy of the heart; 4th, softening connected with an acute alteration in the general nutritive process (as in typhus) ; 5th, softening connected with a chronic alteration in the general nutritive process (as in a variety of chronic diseases) ; 6th, softening which we are not yet enabled to refer to any morbid condition of the heart itself or of the rest of the system.f Suppuration. — The occurrence of an abscess uncomplicated with any other lesion in the walls of the heart, does not unequivocally de- note the previous existence of carditis, although it may afford strong presumptive evidence of the fact : when, however, we find abscess, with lymph or adhesions of recent date, we may rea- sonably infer its inflammatory nature. Dr. Copland has introduced in a note to his inva- luable and profoundly learned article on Dis- * Lectures on Diseases of the Chest, Med. Gaz. vol. xvi. t Otto says that violent exertion appears as in other muscles to render the heart easily broken down ; thus, for instance, it is found very weak in hunted deer. ABNORMAL CONDITIONS OF THE HEART, 637 eases of the Heart,* an abstract of several cases in which pus was found in the substance of the heart. Those quoted from Corvisart, Raikem, and Simonet, and probably that from Dr. Craves,f may be regarded as examples of puru- lent formation following carditis, general or partial. So likewise is Laennec's case, in which, however, the carditis was consequent upon pericarditis. There is no anatomical cha- racter which will enable us to distinguish whe- ther a simple purulent deposit, surrounded by natural muscular texture, be inflammatory or not, for there is no reason why the heart should be exempt from that which we know often occurs in other muscles, namely, non-inflam- matory deposits. Ulceration. — As true carditis seems to be generally admitted to be rare, so we may con- clude that ulceration is equally so. It is by the ulcerative process that some of the perfora- tions or ruptures of the parietes of the heart take place ; it is probable, however, that the great majority of the ulcerations we meet with commence from the surface, and result from membranous inflammation rather than from that of the muscular substance ; the ulcer commences on the surfaces, either in or imme- diately subjacent to the internal or external membrane ; and as it burrows deeply, it may perforate the muscular wall, and so destroy the membrane on the side opposite to that on which the ulceration had commenced. Sometimes an ulceration of this kind gives rise to aneurismal tumours or sacs, very variable in size, projecting from that part of the cavity which corresponds to the artery. It seems evident that these tumours are produced by the pressure of the contained blood distending the thinned and yielding wall of the heart. We shall return to this subject further on in treating of aneurisms of the heart. Induration. — This condition of the muscular structure of the heart seems most probably to be a result of inflammation, especially of the chronic kind. It is generally found in small circumscribed portions ; it may occur in any part of the heart, and may even co-exist with softening : the hardened portion has become particularly firm, is cut with difficulty, and when struck with the scalpel sounds, as Laennec says, like a leather dice-box. It is harder, denser, less elastic, and as regards colour is paler than the hypertrophied muscular tissue. Cartilaginous and osseous transformations. — Induration of the subserous cellular tissue of the heart is in general the precursor of many of these transformations. This indurated portion increasing in thickness gradually assumes the appearance of cartilage — in this cartilage the calcareous particles are deposited. I have not been able to ascertain whether this so-called ossification exhibits, on examination by the mi- croscope, the lamellar arrangement of true bone, as osseous transformations of certain permanent cartilages do, those of the thyroid cartilage for example. These calcareous or osseous patches * Diet, of Medicine, part iv. p. 191. t Lond. Med. and Surg. Journal, vol. vii. or tumours compress the subjacent muscular tissue, and produce atrophy of them, and ac- cording to Andral, sometimes are connected by prolongations of the same material with other calcareous deposits formed round the orifices. Many pathologists believe that these transfor- mations are the result of inflammation. I sup- pose there can be no doubt that they follow an increased afflux of blood, and so they may be considered, although not an immediate, at least a remote effect of inflammation, or rather of the altered nutrition and secretion to which inflam- mation gave rise. In a case recorded by my friend Mr. Robert Smith, of Dublin, the apex of the left ventricle was converted into a dense, white, firm, car- tilaginous structure, the division of which with a scissors required the employment of con- siderable force ; the alteration of structure had extended to some of the carneaj columnar.* Tubercles. — These productions are very rarely if ever met with in the heart. No re- liance can be placed on most of the instances recorded, in consequence of the imperfect and unsatisfactory descriptions accompanying them; what appears to one person to be tubercular may present a totally different aspect to another. Laennec says vaguely, " only three or four times have I met with tubercles in the muscular substance of the heart." And Andral states, that they are never met with in the heart, except when they likewise occur in other muscles. Otto says, "although I have dis- sected a great number of scrofulous men and animals, I have never found a tubercle on the heart, and therefore consider them very rare." Dr. Elliotsonf mentions a case in which there were scrofulous deposits in the walls of the left ventricle, surrounded by white and almost cartilaginous induration. In a case which came under my own observation, in a woman be- tween 50 and 60 years of age, there were several white tumours in the parietes of the right ventricle, each about a quarter of an inch in diameter, of uniform consistence throughout, nor showing any disposition to softening in the centre. Scirrhus. — Equally unsatisfactory are the reports of anatomists respecting this alteration. Rullierand Billard relate cases in which scirrhus had developed itself on the heart. Rullier'sJ case was an instance of degeneration of the whole substance of the heart into a scirrhous mass, which formed irregular knobs on the ex- ternal and internal surfaces of the heart. Bil- lard found three scirrhous tumours embedded in the heart of an infant only three days old.§ Medullary fungus, or encephuloid tumours.— Of these, several instances are quoted by Andral from others, and he describes two whicli he saw himself.|| In the first of Andral's cases the whole of the walls of the right auricle and ventricle were converted into a hard, dirty white substance, traversed by a number of * Dub. Journal, vol. ix. p. 418. t Lumleyan Lectures, p. 32. X Bull, de la Faculte, 1813. S Malad. des Enfans. (I Loc. cit. vol. ii. p. 346. 638 ABNORMAL CONDITIONS OF THE HEART. reddish lines, and possessing all the characters of encephaloid. In the second case, the external wall of the right ventricle was occu- pied by a tumour extending from its apex to its base, which projected so far externally as to lead him to mistake it for a supernumerary heart, and likewise protruded internally into the cavity of the ventricle. In a case which I saw myself, the tumour resembled the well-known encephaloid or cancerous tumour of the liver, being, like it, raised above the surrounding muscular structure, and irregular on its surface. Melanosis. — This deposit is also found very distinctly in the heart. It appears in the form of small spots under the pericardium or endo- cardium, or as tumours in the substance of the ventricle. In a specimen in the Museum of King's College, London, the melanotic deposits are situated, some beneath the pericardium covering the right ventricle, and others on the carneae columnae of the same cavity,immediately subjacent to the endocardium. Neither Andral nor Bouillaud notices the occurrence of me- lanosis in the heart. Hypertrophy of the heart. — When the walls of any of the heart's cavities experience an in- crease of thickness, owing to the developement of the muscular substance, they are said to be in a state of hypertrophy; and there is no morbid state of this organ which is more fre- quently brought under the notice of the phy- sician than this, as affecting the parietes of one or more of its cavities. There is no alteration in the muscular texture apparent to the naked eye, except, perhaps, a slight increase of the red colour — the heart is firm, dense, and elastic ; in short, it presents all those characters which we so often see manifested in the ex- ternal voluntary muscles, the developement of which is increased by frequent use.* Hyper- trophy may affect all the cavities simultaneously, but in general it is limited to one or at most two cavities. The left ventricle is that in which it most frequently occurs, next the right, and lastly and rarely the auricles. Nor does the hypertrophy affect necessarily the whole pa- rietes of the cavity, but sometimes it is limited to a small portion, or to the septum, or to one or more of the carneae columns. In some cases, as Andral remarks, the thickening may be at its maximum at the base of the heart, and diminish gradually towards its apex, which sometimes retains its natural thinness, when all the rest of the parietes are three or even four times as thick as natural ; or at other times, as Cruveilhier observes, becomes so thin that one is astonished that perforation or dila- tation of the heart at its apex is not more com- * Dr. Williams mentions that in leucophlegmatic subjects the muscular texture is soft and flabby and of a duller colour. This is obviously a con- dition resulting from other causes, and not a cha- racter of the hypqTtrophous heart as such. And the threads or laminas of dirty white tissue inter- mingled with the muscular tissue, described by him, seem clearly the result of the inflammation which caused the concomitant adhesion of the peri- cardium. In the same light I would regard the dense fibrous tissue described and delineated by Carswell. — See Med. Gax. vol. xvi. p. 915. mon. In other individuals again the thickening is equal and uniform from the base to the apex, which then loses its pointed form and acquires a rounded shape. Lastly, it sometimes happens that the hypertrophy is greatest about midway between the apex and base of the heart, or is even exclusively confined to that part. When the septum is principally affected, the capacity of the right ventricle is so diminished that it sometimes looks like a small appendix attached to the left ventricle.* When the hypertrophy affects chiefly or exclusively the right ventricle, the apex of the heart seems to be formed by it, whereas in the normal state the apex belongs to the left ventricle. An hypertrophous state of the parietes of all the cavities not only affects the form of the heart by changing it from the oblong to the spherical, but, as was first noticed by Dr. Hope,f its position is altered ; '* as the dia- phragm does not retire sufficiently to yield space downwards for the enlarged organ, it assumes an unnaturally horizontal position, encroaching so far upon the left cavity of the chest as sometimes to force the lung upwards as high as the level of the fourth rib or even higher." BertinJ distinguishes three varieties of hy- pertrophy of the heart. 1. That in which the hypertrophy is not accompanied with any alte- ration in the capacity of the cavities of the heart — simple hypertrophy. 2. That in which there is dilatation of the cavity along with the increased substance of its walls — excentric hyper-trophy or active aneurism of Corvisart. 3. Where the capacity of the ventricle is dimi- nished as if the walls had encroached by their increase of thickness upon the cavity, or as Bouillaud expresses it, as if the internal mus- cular layers and the carneae columnae were prin- cipally the seat of hypertrophy — concentric hy- pertrophy.^ Of these the most frequent is that which is accompanied by dilatation, the dilata- * Cruveilhier doubts the occurrence of partial hypertrophy affecting the septum or one or more carneas columnae. t Cyclop, of Pract. Med. art. Hypertrophy of the Heart. | Maladies du Cceur. § A certain standard of health is absolutely necessary to enable us to determine as to the ex- istence of disease. With this view we transcribe here the table of weight and dimensions drawn up by Bouillaud as the average of health. In an adult of ordinary size and good constitu- tion the mean weight = 8 to 9 oz. ; mean circumfe- reuce = 8 to 9 inches; mean of the longitudinal and transverse diameters = 3i inches (the latter generally predominates slightly over the former) ; the mean of the antero-posterior diameter =2 inches. Mean thickness of the walls of left ventricle at the base = . . . . 6 to 7 lines. Ditto, right ventricle at the base = . 2i lines. Ditto, left auricle = . . .14 lines. Ditto, right auricle=. . . 1 line. The average capacity of the ventricles is suffi- cient to contain a hen's egg (that of the right ven- tricle slightly exceeding the left). For some useful observations on this subject, and on the normal weight, bulk, &c. of the heart in relation toother viscera, see Dr. Clendinning's Lec- tures in Med. Gazette, vol. xvit ABNORMAL CONDITIONS OF THE HEART. 639 tion in all probability preceding and giving rise to the hypertrophy by rendering an increased force of contraction necessary. Simple hyper- trophy is the least common, according to Bouillaud ; concentric hypertrophy, according to this physician, is not rare. Considerable doubt, however, has been excited recently by the high authority of M. Cruveilhier as to the real existence during life of such a condition as this. This anatomist believes the diminished cavity to be merely the result of a tonic con- traction of the muscular wall of the ventricle in death. " The concentrically hypertrophied hearts of Bertin and Bouillaud appear to me," he says, " to be hearts more or less hypertro- phied, which death surprised in all their energy of contractility."* The hearts of all those examined by Cruveilhier, who died by the executioner, presented to his observation to a great degree the double phenomenon of in- creased thickness of walls and diminished cavity, and he has observed the same with per- sons who died a violent death. f On one occa- sion I was particularly struck with a similar condition of the heart of a donkey which had been accidentally transfixed by a large trocar, whereby the death of the animal was caused in a few minutes. The muscular structure of the heart was singularly dense. It had contracted at its apex quite to a sharp point, and on cut- ting into it the cavity of the left ventricle ap- peared almost obliterated, and the muscular wall much increased in thickness. I have many times, too, observed the fact noticed by Cruveilhier, that the cavity may be easily en- larged or restored to its natural dimensions by introducing the finger and dilating it, or still more easily, if the heart have been macerated in water for a short time previously. This fact is further confirmed by Dr. Budd, who sup- ports the views of Cruveilhier in an interesting paper in the last volume of the Medico-Chimr- gical Transactions. In one of Dr. Budd's cases the thickness of the parietes of the left ventricle eighteen hours after death varied from an inch to an inch and a half, on a transverse section made at a distance from the apex of one-third of its length, and the cavity was not large enough to hold the second phalanx of the thumb, and was almost filled by the carnece columnae. This heart, in its open state, was put to macerate; no force ivas applied to extend it. At the end of some days, on being folded up, it was found to have dilated very conside- rably, so that the left ventricle could not then be said to be smaller than natural. Dr. Budd argues against the existence of the diminished cavity from the fact that of eight cases collected by him, no one afforded signs, either during life or after death, of any obstacle to the circu- lation through the heart. There were no irre- gularity of pulse, no dropsy during life, no di- latation of the right cavities after death, pheno- mena which, it may be said, must of necessity be present if there be an obstacle to the circu- * Diet, do Med. et Chir. Prat. art. Hypertrophic, t Mr. Jackson and Dr. Budd have observed this state of the heart in persons who died of cholera. lation in the heart. It is impossible, as he states, to conceive that a left ventricle, which could scarcely hold an almond, should offer no obstacle to the circulation through the heart. Yet Laennec has recorded a case in which the parietes of the left ventricle had acquired the thickness of from an inch to an inch and a half, and the cavity seemed capable at most of con- taining an almond stripped of its shell. Yet the day before the patient's death his pulse was natural, the breathing perfectly free, " and nothing," says Laennec, " led me to suppose that this man had a disease of his heart." Hypertrophy with dilatation. — It is in this morbid condition that the heart acquires the greatest increase of size as well as the most striking alteration of form. The cor bovinum of some authors, so called from its enormous size, affords an instance of an extreme develope- ment of this form of disease. The extent to which the heart may become enlarged in this way is quite extraordinary. Of certain cases recorded by Bouillaud, in one the right ventri- cle was large enough to contain a goose's egg, and the left, still larger, the closed hand of a female; in another, the left ventricle was simi- larly increased in capacity. In a third, the right auricle of a child, aged seven years, was so dilated as to contain a coagulum as large as the closed hand of an adult. The thickness of the left ventricle in Bouillaud's cases varied from 7 to 14 lines, that of the right 3 to 5 lines; but in some instances it was as considerable as from 8 to 10 lines or 11 to 16 lines. The weight of the heart, in some instances, trebled the na- tural ; thus in one case of general hypertrophy the weight was 22 ounces, and others weighed from 13 to 20 ounces. The circumference of the heart was often increased to twelve inches, the longitudinal diameter five inches, and the transverse eight inches. In a patient who died at the Hotel Dieu in 1834, the heart measured fifteen inches and a half at its base. Hypertro- phy seldom occurs in the auricles, except when accompanied by dilatation : the musculi pecti- nati are generally the seat of the increased mus- cular developement, and as the number and developement of these muscular columns is greater in the right auricle than in the left in the normal state, (in the left they ara only found in the auricular appendage,) the remark of Dr. Hope follows almost as a matter of course, namely, that in the right auricle hypertrophy proceeds to the greatest extent, its walls being sometimes rendered nearly equal in thickness to those of the right ventricle in the normal state. In the vast majority of cases of this kind the produces of inflammatory states of the pericar- dium or endocardium, or its appendages, are present; in short, a diseased slate of the valves constantly co-exists with hypertrophy and dila- tation. These conditions of the cavities are very frequently traceable to some obstacle to the cir- culation through the heart, and sometimes it would seem that the valvular disease preceded and gave rise to the hypertrophous and dilated cavity; but it is not impossible nor unlikely that the valvular disease may follow the hyper- 640 ABNORMAL CONDITIONS OF THE HEART. trophy, and may result from the violence of contraction of the enlarged ventricle. Dilata- tion of the aorta at its commencement and its arch is frequently the consequence of this dis- ease in the left ventricle, and dilatation of the pulmonary artery ensues upon it in the right ventricle. Dilatation of the cavities of the heart. — " When the heart is incapable of sufficiently expelling its contents, whether in consequence of obstruction in the vessels from it, of regurgi- tation into it through imperfect valves, of want of power, of irritability, or of both, it becomes distended, and in time permanently dilated."* We have already described that kind of dilata- tion which is the most common, namely, that accompanied by hypertrophy ; dilatation also occurs in connexion with an opposite condition of the parietes, namely, attenuation of them. The muscular tissue has lost its tone, and yields, as it were, without resistance to the dis- tending force. It is laid down by authors that a third variety of dilatation may exist, what they call simple dilatation, or that in which, while the cavity is dilated, the parietes are of their na- tural size. It seems to me impossible that any cavity of the heart can, in a dilated state, conti- nue of the natural thickness withouthypertrophy, in the absence of which dilatation implies neces- sarily a diminution in thickness; during dia- stole the parietes of the heart's cavities are thin- ner than during systole ; what a contracted muscle gains in one dimension it loses in ano- ther ; and the same may be said of a relaxed or distended muscle. Again, if we contrast a con- tracted with a dilated bladder, it seems evident that we cannot inflate the former, however in- completely, without producing a manifest dimi- nution in the thickness of its walls. Hence I infer, that if the parietes of any cavity be per- fectly natural, they must become thinned under the influence of the force which produces the dilatation; and, on the other hand, if we find that the parietes of a dilated cavity possess the normal thickness, we may be assured that it is slightly hypertrophous. It appears then to be most correct to limit the varieties of dilatation to two, that with hypertrophy and that with attenuation, or the passive aneurism of Corvisart. In this latter form of dilatation, then, we see a manifest alteration of the muscular tissue; it is paler, softer, less resisting, less elastic than natural. When the heart is emptied of its con- tents, the walls do not at all return upon them- selves, but remain flaccid ; nor when cut do they show any disposition to retract; and it is this state of the muscular substance which will serve best to enable the anatomist to distinguish morbid dilatations from those which result from mechanical distension of the cavity by a coagu- lum formed at the time of deadi. An obvi- ously diseased state of both the internal and external membranous coverings of the heart is constantly present along with this form of dila- tation. These membranes lose their transpa- rency in several parts, apparently from some abnormal deposit subjacent to them : the white * Dr. Williams, loc. cit. spot so often seen upon the external surface of the right ventricle is an almost invariable at- tendant upon the dilated heart. Dilatation may affect any or all of the heart's cavities ; but it is met with by far the most frequently in the right ventricle, and very commonly both ven- tricles are dilated, in which case the right cavity is generally more capacious than the left. An extreme case of dilatation is afforded in an example quoted by Bouillaud : " the right cavities were so dilated and their walls so at- tenuated, that the auricle was converted into a kind of transparent membrane, and the ventricle was reduced only to the ordinary thickness of the auricle.'' In determining as to the degree of attenua- tion of the walls which may accompany any particular case of dilatation of the auricles, the anatomist must bear in mind that even in the natural state the interval between the musculi pectinati of the right auricle is only composed of the endocardium and pericardium, separated by a very fine and transparent cellular tissue, and by a few muscular fibres crossing obliquely from one pectinate muscle to the next one. I have twice seen a perfectly natural right auricle carefully put up as a museum specimen of morbid attenuation of the parietes, owing to ignorance or forgetfulness of this fact. Dilatation of the orifices of the heart. — As a natural result of dilated cavities we meet with dilated orifices of the heart, and the enlarge- ment of which again produces in many cases insufficiency of the valves. Bouillaud gives the measurement of the auriculo-ventricular orifice (which is the most liable to dilatation) in three hearts ; in one it measured five inches in circumference, and in another four inches three lines, while in a third the dilatation was stated to be so great that the tricuspid valve could not be closed. Aneurism of the heart. — A diseased state of the heart occurs not unfrequently, strongly analogous to that which under the same name is so well known as occurring in the arterial system. Most of the varieties too of arterial aneurism find their analogues in the heart : thus we have, 1. the aneurism by simple dila- tation, or true aneurism, resulting from partial dilatation of one of the heart's cavities; 2. the false aneurism or that resulting from rup- ture of one or more of the textures entering into the formation of the heart's parietes; 3. we find the dissecting aneurism analogous to that remarkable form of arterial aneurism first described by the late Mr. Shakelton ; 4. not improbably, we also meet with what is analogous to the varicose aneurism, and may be designated spontaneous varicose aneurism of the heart. To the zeal and acuteness of Mr. Thurnam * morbid anatomists are much in- debted for his having arranged, compared, and classified a considerable number of cases of aneurismal dilatations connected with the heart, either observed by himself, or preserved and * Vide his valuable monograph on Aneurisms of the Heart in Med. Chir. Trans, vol. xxi. An ap- pendix containing references to cases is added. ABNORMAL CONDITIONS OF THE HEART. 041 recorded by others, whence lie has been able distinctly to prove the analogies above-men- tioned, and by which much light has been thrown upon those forms of disease. The partial dilatation of one of the cavities, or true aneurism, is by far the most com- mon of the varieties above-mentioned. In its early stage this disease consists in little more than a bulging of the wall of the ventricle or auricle in a certain direction ; as this in- creases a pouch or sac is formed, which com- municates with the heart's cavity by a more or less narrow opening. In some cases this sac does not extend beyond the external surface of the heart, nor would it be detected, were the anatomist to content himself with merely ex- amining the exterior, it is as it were lodged in the fleshy substance of the ventricular paries; but in other instances a tumour is formed pro- jecting considerably beyond the exterior. As in arterial aneurisms, the sacs frequently contain laminated coagula, and, as might be expected (i priori, the larger the cavity and the narrower its orifice of communication, the more abun- dant is this lamellar deposit. One or more aneurismal sacs may belong to the same cavity: thus, in fifty-two out of fifty-eight cases col- lected by Mr. Thurnam, only one aneurism existed in each ; but in four cases two were met with in each; in one there were three, and in another four incipient aneurisms. In two instances, Mr. Thurnam states, it is not improbable that two sacs which were originally distinct had coalesced, so as to form a single aneurism, and in another case three sacs ap- pear to have united in this way. We find the aneurismal pouches of all sizes : in nine of the cases referred to in Mr. Thurnam 's memoir, the size might be compared to that of nuts ; in twenty, to that of walnuts; in seven, to fowl's eggs; in fourteen, to oranges; and in nine cases, it almost or quite equalled that of the healthy heart itself. We cannot always satisfactorily ascertain what textures enter into the formation of these sacs ; however, in the majority of cases, the three structures of which the heart's parietes are composed are found in the walls of these sacs; in others the muscular tissue has disappeared, atrophied probably by the pressure, and the wall is composed only of the endocardium and pericardium, and in others again the endocardium is wanting, and the muscular fibres and the pericardium are the only component elements.* In some cases the wall of the sac is strengthened by an ad- hesion formed with the loose layer of the peri- cardium. These aneurisms are always in connection with the left ventricle or left auricle; very rarely however with the latter, and never with the right cavities. In the paper already quoted from, Mr. Thurnam has collected references to fifty-eight cases of aneurism of the left ven- tricle, and eleven of the left auricle. All parts of the ventricle are liable to aneurismal dila- tation, but it occurs most frequently at the apex : next in frequency it is found at dif- * Vide Thurnam, loc. cif. p. 219. VOL. II. ferent points of the base; less frequently still it occurs in the lateral walls at situations in- termediate to the two last-named, and very rarely it is met with in the interventricular septum. I will give the description of auricular aneu- rism in Mr. Thurnam 's words: " The dis- ease would appear, from the preparations I have inspected, and the cases which have been re- corded, to have been nearly uniformly of the diffused kind, and to have generally involved the entire sinus of the auricle. The dilated walls of the cavity are often thickened and the seat of fibro-cellular degeneration. The lining membrane is opaque, rough, and otherwise diseased, and in some cases even ossified, and is lined with fibrinous layers, very similar to those met with in arterial aneurisms. In all these cases, the lining membrane appears to have been continued into the interior of the dilated portion, which consequently merits the name true aneurism. Occasionally the dilatation is confined to the auricular appendage, which becomes extensively distended with lamellated concretions."* The false aneurism, or that resulting from rupture, must be spoken of merely as a pos- sible and probable occurrence. I know of no unequivocal example of it; but inasmuch as we must admit that partial rupture of the heart's wall may take place, we cannot deny the possibility of the production of cardiac aneurism in a manner similar to that in which arterial false aneurism is produced. Dr. Hope describes cases, which Mr. Thur- nam very aptly compares to " the dissecting aneurism." In those cases, Dr. Hope says, " steatoinatous degeneration had caused the formation of a canal from the aorta underneath one of the sigmoid valves and the internal membrane of the left ventricle." But Mr. Thurnam's explanation seems to me much more likely to be the true one. He supposes that the aneurisms had been originally formed in the ventricle, and had subsequently commu- nicated with the aorta, as a consequence of the co-existent disease of the valves of that vessel. The possibility of the formation of an aneu- rism resembling theimricose aneurism, has been likewise suggested by Mr. Thurnam, from the occurrence of aneurismal pouches in the sep- tum ventriculorum. If such an aneurism were to burst, it would establish a communication with the right ventricle, a portion of the ve- nous system — thus producing " a lesion alto- gether analogous to that which results from the wound of an artery and its accompanying vein, and to which the name of spontaneous varicose aneurism of the heart is perfectly applicable." Mr. Thurnam mentions a fourth form of aneurism which is not without its analogue in the arterial system, namely, that in which the aneurismal sac is formed by the endocardium and pericardium. This may be compared with a variety of external aneurism in which the lining membrane of the vessel protrudes through a rupture in the middle tunic, constituting a * Loc. cit. p. 245. 2 v 642 ABNORMAL CONDITIONS OF THE HEART. lesion which has been sometimes designated ' " aiieurisma herniosum," and sometimes " internal mixed aneurism." This form of arterial aneurism has been described by Haller, Dubois, Dupuytren, and Breschet. In a large number of these cases of aneu- rism of the heart, the pericardium has been at some period or other of the disease more or less extensively inflamed, and adhesions are consequently found : the endocardium like- wise frequently exhibits marks of inflammatory action, opacities, white spots, &c. and this sometimes extends to the valves. In some the muscular substance in the neighbourhood of the sac is degenerated, and assumes the cellulo- fibrous form.* Atrop/n/ of the heart. — The heart, or a por- tion of it, may be said to be in the state of atrophy, when its muscular fibres are pale, soft, easily torn, inelastic, attenuated, so that the thickness of the parietes is greatly di- minished, and the pericardium covering the heart or the atrophied part of it, is shrivelled and wrinkled. When atrophy affects the whole heart, that organ becomes much diminished in size, the capacity of its several cavities being proportionally diminished ; and in some in- stances the diminution of the general size ap- pears to be more at the expense of the dimen- sions of the cavities than of the thickness of the walls. Morbid deposit of fat on the heart (fatty degeneration of some authors). There is an alteration met with not uncommonly in the muscles of animal life, which is very often de- scribed as the fatty degeneration of muscle, but which is in truth an atrophy of the mus- cular tissue, and not at all a transformation into fat. This condition, which resembles fat only in its yellow colour, and may be easily distinguished from it by its fibrous form, has never, I believe, been met with in the heart; a perfect cessation from active contraction must be essential to its production; and as such a state of quiescence cannot occur in the heart during life, this form of degenerate muscular tissue is not found in that organ. We do, how- ever, meet with cases frequently, in which fat seems to take the place of the muscular fibres of the heart: in proportion as they appear to waste away the fat is deposited under the serous membrane, until the muscular parietes of the heart are reduced to a very thin lamina, of a pale colour and easily torn, between which and the pericardium a thick stratum of fat is deposited, so that a superficial examination might lead one to suppose that the walls of the heart were wholly converted into this tissue. The ventricles are generally, if not uniformly, the seat of this deposit, which must be re- garded as an increase in the deposit which is * On the subject of aneurisms of the heart, the reader may consult with benefit Corvisart's clas- sical work, Adams in Dublin Hosp. Rep. vol. iv., Dreschet sur IWneurysme Faux consecutif du Cieur, Rep. Gen. d'Anat. t. iii., Dr. Hope's work, Elliotson's Lectures on Diseases of the Heart, but especially the admirable paper of Mr. Thurnam. found naturally along the course of the coro- nary arteries. It occurs chiefly in old persons, and it is difficult to say whether the muscular atrophy which is always present is a con- sequence of the fatty deposit, or precedes it. So enfeebled has the muscular tissue become that persons labouring under this disease very commonly die of a rupture, or rather a giving way, of the wall of one of the ventricles. It occurs in persons of debilitated habits, who either are incapable of active exertion or from circumstances never attempt it, and, what is remarkable, the subjects of this disease are frequently very emaciated : thus M. Bizot* found this condition in fourteen out of twenty- nine emaciated females. The disease is like- wise more common in women than in men ; and sometimes free oil is present in the blood in inordinate quantity. Such I believe to be the correct history of this state of the heart, of which most erroneous notions have been formed, owing in a great measure to the name under which the disease has been so often described. The description which I venture to offer has been drawn up from several cases of the disease in various grades of the deposit, which have come under my observation, and on comparing this description with some of the best detailed cases on record, it seems perfectly to con- sist with the appearances described in them. In Mr. Adams' case,f for instance, " the right ventricle seemed composed of fat, of a deep yellow colour through ' most of its sub- stance. The reticulated lining of the ventricle, which here and there allowed the fat to appear between its fibres, alone presented any ap- pearance of muscular structure. The left ven- tricle was very thin, and its whole surface was covered with a layer of fat. Beneath this the muscular structure was not a line in thickness, and was soft, easily torn, and like liver." Two cases, recorded by Mr. R. Smithy presented the remarkable concomitant of an oily con- dition of the blood ; in one " numerous glo- bules of oil were found floating on the surface of the blood which escaped from the divided vessels ;" and in the other " the surface of the blood was thickly covered with globules of limpid oil." In this last case the condition of the heart's substance is described as follows : " the heart was remarkably soft, pale, and flaccid, its substance most easily broken, and its surface covered with a layer of fat a quarter of an inch in depth ; the parietes of the ven- tricles were thin." The anatomical condition of the former case is not so precisely described as to admit of comparison. The subjects of both these cases were old women, one aged ninety, the other seventy ; and the former died of rupture of the left ventricle. I am quite unable to account for the follow- ing description of a case by Dr. Elliotson. He says, " I once saw the muscular substance of the heart completely changed, except at the m Mem. de la Soc. Med. d 'Observation, t Dublin Hosp. Rep. vol. iv. p. 396. \ Dublin Journal, vol. ix. p. 412. ABNORMAL CONDITIONS OF THE HEART. 043* svrface, to fat. A mere layer of red muscular structure covered the internal and external parts of the heart and the columns earner : within every spot was fatty matter."* Rupture, of the heart. — A degenerate con- dition of the muscular tissue is the most com- mon cause of rupture of the heart: the states last described are those in which it most fre- quently occurs ; they correspond to the senile softening of Blaud :f the wall literally gives way at a certain point, and a laceration fre- quently to a very trifling extent is found in that situation on examination after death : in some cases, moreover, several ruptures are found in the wall of the same cavity, and sometimes the rupture is very extensive, or it is large in- ternally and small externally, or vice versa. Any of the cavities may afford examples of this form of rupture, but the left ventricle is by far the most frequent seat of it, as may be understood from the following numerical state- ment by Ollivier: " out of forty-nine cases the rupture was seated in the left ventricle in thirty- four, in the right ventricle in eight, in the left auricle in three, and in two cases the ventricles presented several ruptures. In these cases the apex was the situation of the rupture in nine ; in the rest the rupture took place near the base. Rupture, however, may occur in a healthy state of the organ, from violent bodily exertion; of this a remarkable example was afforded in the case of one of Whitbread's draymen, who in attempting to raise a butt of porter, fell dead, from a large laceration of the left ventricle, the structure of which was per- fectly healthy. I had lately an opportunity of examining the preparation of this heart in the Museum of Guy's Hospital. Rupture is also found to ensue upon abscess in the heart, or upon ulceration and conse- quent perforation ; it is sometimes caused by dilatation of it, and sometimes by contraction of one or more of the orifices. Partial rupture may occur, i. e. the external fibres may be ruptured to a certain depth, without penetrating the cavity, or the internal ones may be similarly torn, the exterior being unaffected. A more remarkable kind of par- tial rupture is that in which the carnese co- lumns or chorda; tendinea? are engaged. Cases of this form of rupture seem to have been detailed first by Corvisart, who attributed the rupture to violent efforts. Other cases have been subsequently recorded by Cheyne, Adams, and Townsend. In Dr. Cheyne's case, " the internal surface of the left ventricle was much inflamed, several irregular excrescences were attached to the mitral and semilunar valves. The chorda? tendinea?, which connected the larger portion of the mitral valve to the wall of the left ventricle, were torn off just at the point of their insertion into the edge of the valve; four of these ruptured tendons hung loose into the ventricle."! * Croonian Lectures on the Heart, p. 32. t bland, Bibl. Med. an. 1820. X Dublin Hosp. Rep. vol. iv. On the subject of rupture of the heart the reader may consult Olli- MoRBID STATES OF THE MEMBRANES OF THE HEART. I. Morbid slates of the pericardium. — 1 . Pe- ricarditis. The morbid changes of the serous pericardium which most frequently come under the notice of the anatomist, are those which are consequent upon inflammation. What the alterations are which indicate the first onset of inflammatory action it is not easy to determine precisely, as the opportunities of inspecting the parts in this early stage of peri- carditis are extremely rare. The following, however, may be stated as indicative of the earliest period of pericarditis. The natural exhalation becomes diminished or totally suppressed, and consequently the surfaces of the membrane do not present their usual moist appearance ; the visceral layer of the pericar- dium is not so transparent as in the natural state, and several red points, which to the naked eye appear like extravasations of blood, are manifested on a considerable portion of the membrane. These spots, however, are not extravasations, but when examined with a lens, they are seen to be produced by a close net- work of extremely minute capillary vessels ; as inflammation advances these spots increase in number, neighbouring ones coalesce, a more or less diffused redness is produced, as well from vessels subjacent to, as in the membrane, the membrane becomes less and less transparent, and now an exudation is distinctly formed on its surface of a very soft semifluid material (co- agulable lymph), which, on looking carefully along the inflamed surface, is seen to be de- veloped in minute granules. The further pro- gress of the disease is characterised by the increased deposition of this plastic material, and the effusion of a straw-coloured serous fluid into the bag of the pericardium. These morbid changes, of course, vary in extent ; but it is not uncommon to find them extending over the greatest part or even the whole heart, so that in some cases a second complete enve- lope is formed for the heart between the visce- ral and parietal layers of the serous pericar- dium ; on the other hand a very circumscribed spot may be occupied by these changes, not ex- ceeding a half-crown or a crown piece in circumfe- rence ; but we seldom or never have opportu- nities of seeing the disease on this limited scale in so early a stage, and judge of its occurrence only from the existence of alterations which may justly be regarded as its sequela?. Certain varieties are observed as regards the form assumed by the lymph, and the quantity of the fluid effused in this disease. The lymph varies in its characters ; almost always depo- sited in a membranous form, it is sometimes quite smooth and uniform on its free sur- face ; at other times it is rough, and hangs in flocculi into the fluid contained in the sac of the pericardium ; again it presents a reticulate appearance, compared by Corvisart, Laennec, and Bertin, to the inner surface of the second vicr's article (Cceur Rupture) in Diet, de Med., Townsend in Cyclop. Pract. Med. vol. iv. p. 630., and Bouillaud's work. 2 u 2 644 ABNORMAL CONDITIONS OF THE HEART. stomach of the calf, or, as Laennec suggested, to the appearance produced by quickly se- parating two slabs of marble which have been applied together, with a small quantity of butter or some similar substance between them. The depth of the depressions iri this false membrane varies with the thickness of the membrane itself. Shortly after its deposition the lymph is very tender and easily torn, but when it has been some time deposited, it ac- quires a considerable power of resistance. The effused fluid in pericarditis varies likewise in quality and quantity. In some cases it is whey-coloured, with flocculi of lymph floating in it ; in others it is of a yellowish colour, ap- proaching that of pus, and in some degree of the same consistence : sometimes it is of a brownish colour. When it is in very small quantity it is less turbid ; when in large quan- tity it resembles whey. In some cases the quantity is very considerable. It may be said to vary from a few ounces to more than a pint ; but in some extreme cases it goes even far be- yond this; thus Corvisart mentions a case in which the effused fluid amounted to eight pounds, and in one described by Bertin the distended pericardium formed a bag seven or eight inches broad, five deep, and ten or eleven in height. Sometimes the effusion cannot be distinguished from pus. The coagulable lymph is effused not only on the free surface of the visceral layer of the pe- ricardium, but likewise on that of the parietal layer. That which is effused upon this latter layer is, however, often much thinner and more delicate. These two deposits of lymph are continuous with each other at the reflection of the serous pericardium from the great vessels on to the muscular fibres. When the effused fluid hasbeen lenioved by absorption, the two pseudo- membranes being brought into apposition with each other, areas it were glued together; they become organised by new vessels shooting into them from the cardiac vessels, and at length they assume the form of cellular tissue. The •cavity of the pericardium thus becomes oblite- rated by the development of this new cellular tissue. The adhesions thus formed are more or less extensive according to the extent of the primitive inflammation, so that in some cases the pericardium is universally adherent to the heart ; in others the adhesion is circumscribed within very narrow limits ; in this latter case the new cellular membrane is often of conside- rable length, inasmuch as the spots to which it adheres on the opposed layers of serous mem- brane do not at all correspond ; but when the adhesion is extensive, the connecting cellular membrane is generally short and close, so much so in some cases that the pericardium and heart appear to be completely identified. The mus- cular substance subjacent to the inflamed peri- cardium sometimes appeals to participate in the inflammatory process, acquires a greater hue of redness than is natural, and becomes softer, and loses to a greater or less degree its cohesive power. Such is the ordinary course and termination of pericarditis. Every museum contains many specimens illustrative of the different stages of this disease. The cellular adhesion which fills up the pericardial cavity occasionally exhibits further alterations. Sometimes we find it infil- trated with serum, and quite anasarcous; at other times a sero-purulent or purulent fluid is effused into it. It becomes condensed, fibrous in its character; or cartilaginous or fibro-cartilaginous or even osseous plates are formed in it, which sometimes are of so large a size that the heart appears as if enveloped in an osseous case. This cartilaginous or osseous deposit, however, sometimes takes place in the fibrous pericardium. Dr. Hodgkin mentions a case of osseous trans- formation so extensive that the osseous plate occupied a large portion of the base of the heart, where it formed a complete bony ring, the apex of the heart, however, being; left at liberty. A somewhat similar case is recorded by my friend Mr. Smith. " The pericardium was united to the surface of the heart by close and old adhesions, and around the base of the organ bony matter was deposited in considera- ble quantity, apparently between the two serous layers of the pericardium ; it formed an osseous belt surrounding nearly theentireofthebase ofthe heart ; its surface flat and rough, its margin irregular and waving, and its average breadth about one inch. This bony girdle penetrated into the substance of the ventricles, and reached in some parts almost to the lining membrane of the latter."* In Mr. Burns' case the whole extent of the pericardium covering the ventricles, and the ventricles themselves, except about a cubic inch at the apex of the heart, were ossified and firm as the skull. White spot on the heart. — -There is no ap- pearance with which anatomists are more familiar than the white spots on the heart. A single portion of white opaque, or nearly opaque membrane, situated on the anterior part of the right ventricle nearer its apex than its base, and varying in circumference from that of a shilling to that of a half-crown, as thick as the pericardium itself and sometimes conside- rably thicker, constitutes what I have most fre- quently seen. They may be found, however, oc- casionally on the posterior surface as well as the anterior, on the left side as well as the right, on the auricles as well as the ventricles. On careful examination, it is evident that the opa- city is occasioned by an adventitious deposit. This deposit, in a great number of the cases in which I have examined it, consisted of a thin lamina of condensed cellular membrane adherent to the free surface of the visceral layer of the pericardium, which could easily be dissected off, and which I have often peeled off with my fingers, leaving the pericardium appa- rently as if no deposit had been found there. Dr. Baillie, and more recently Laennec and Louis, testify to the facility with which it may be dissected off. Others, however, affirm that the deposit is most frequently under the serous covering of the heart, and consequently in the subserous cellular tissue by which that layer is connected to the heart. Corvisart * Dub. Journ, vol. ix. p. 419. ABNORMAL CONDITIONS OF THE HEART. 645 maintains this opinion exclusively, and Dr. Hodgkin states his belief that in by far the greater number of eases these patches depend on a deposit on the attached surface. This writer adds — " From the circumstance of their being often found immediately under the ster- num, and from their being occasionally met with on other parts of the heart, to which a firm and resisting body has been unusually opposed ; as for example, when a bony deposit has taken place beneath the reflected pericardium, or when an uneven and remarkably indurated liver has, even through the diaphragm, presented an unequal pressure against a particular part of the heart, I have thought it probable that such pressure, aided by the movements of the heart itself, may have led to the production of these spots. These formations may certainly take place at a very early period of life. I have met with one rather loose and thick, but in other respects perfectly resembling those found in the adult, on the right ventricle of a child only ten weeks old. Similar thickening of the close pericardium sometimes marks the course of the coronary arteries and their brandies; and this circumstance amongst others tends to con- firm the idea which I entertain as to its mode of formation."* Mr. T. VV. King, in an Essay on this subject in the sixth number of Guy's Hospital Reports, records a very remarkable example of the opa- city. The patch, " a uniform whitish thicken- ing of the close pericardium," nearly equalled in extent the anterior surface of the right ven- tricle, and was extended over the anterior sur- face of the pulmonary artery as far as its bifur- cation. Two similar patches were found on the under surface of the ventricle. Mr. King inclines to the opinion that this deposit is seated in the proper tissue of the serous mem- brane, and considers it always inflammatory and pretty constantly the effect of friction and irritation. " The situation of these patches," observes Mr. King," whenever they occur, im- plies to my min d a egree of attrition at the part more than belongs to the pericardium ge- nerally. They are found on the surface of the right auricle almost as frequently as on the ven- tricle, but not in so morbid a form ; and much more divided, even minute, and often clustered like the rippling of the sand at ebb-tide. One is not unfrequently seen along the anterior face of the great pulmonary artery. All these relate to the right side of the heart, which all pathologists are aware is often, and more than the left, the subject of distensions. The patches may occasionally, perhaps, be seen on any part of the close pericardium. I have seen them behind the left pulmonary veins ; but, omitting this instance, the next most com- mon appearance of the kind is that of length- ened, narrow, winding, and even branching lines immediately over the great vessels of the ventricles whenever they are the subject of con- siderable dilatation. Here, also, we have evi- dence of a disproportionate space of attrition, resulting from undue prominence." *Lect. on Morb. iinat. of serous membranes, p. 98. I am not aware of any well-authenticated instance of ulceration or gangrene of the peri- cardium. In cases of ulcerative perforation of the heart, it may be said, however, that the pe- ricardium ulcerates as the other parts do. Tubercular formations. — Tubercles, whether cancerous, melanotic, or scrofulous, are formed subjacent to either serous layer of the pericar- dium ; sometimes, and most frequently they are deposited between the visceral layer and the heart, or they may be found between the fibrous pericardium and the parietal aspect of the se- rous layer. Cysts. — The serous cysts which are described as occurring in the heart are sometimes formed immediately subjacent to the serous membrane, and project into the pericardial sac. Accord- ing to Andral they occur most frequently in this situation. Similar cysts have been found between the fibrous pericardium and its serous lining. Hi/drops pericardii or hydropericardium.— This disease consists in an undue accumulation of fluid in the sac of the pericardium. The fluid is either simply serous, of yellowish cha- racter, or it may be of a brownish or reddish hue. In quantity it rarely exceeds two pints. The effusion is not generally attended with any evident morbid change either of the heart or its membranes, excepting that in cases of some standing, the heart seems somewhat atrophied, and the pericardium has lost its perfect trans- parency. Pneumopericardium. — The presence of air in the pericardium, as the effect of morbid action during life, must be very rare. Laennec, how- ever, speaks very confidently of its existence. " Sometimes," he says, " the air is combined with a liquid, and this is by much the most frequent case ; at other times the pericardium is distended by air alone." Could the cases of dry pericardium related by Baillie have been produced by the developementofairin its cavity ? Morbid states of the endocardium. — 1. En- docarditis. The lining membrane of the heart is so similar in its structure and properties to the pericardium, that their morbid states are very similar likewise. The constant contact of the blood with the former membrane serves, however, to modify considerably the anatomical characters of disease in it. We want, I think, satisfactory proofs of the changes induced by endocarditis in its earliest stage; these changes are described to be, redness of the membrane, with a more or less thickened or swollen condi- tion of it; but the redness is not the result of capillary injection, but seems to be a stain on the membrane, the result of contact with the blood. The stain is not merely superficial, but has sunk into the substance of the tissue, and it cannot consequently be washed off. The lining membrane of the heart is often found stained of a red colour as a post-mortem result; and this is invariably the case in hearts examined after putrefaction has commenced. The blood contained in the heart has begun to alter, various gases are given out, and the inter- nal membrane more readily imbibes the colour- ing matter that is brought in contact with it. 646 ABNORMAL CONDITIONS OF THE HEART. Can this redness be distinguished from that which is consequent upon inflammation ? It seems to me that there is no anutumical charac- ter by which the true nature of the discoloration can be proved. The anatomist must be guided in coming to a conclusion upon the question by concomitant circumstances, of which the time which has elapsed after death, the quan- tity and quality of the blood in the heart, and the state of the other organs or textures of the body, are the most important. If the examina- tion has been made soon after death, that is, within twenty-four hours, if the blood in the heart presents no undue predominance of co- louring matter, nor has undergone any decom- position, and if the other tissues retain their na- tural state, and show no unusual tendency to putrefaction, the redness may be inferred to be morbid and inflammatory; but this inference is confirmed with the utmost degree of certainty, if the redness is accompanied by an effusion of coagulable lymph or of pus, and by an unequi- vocal thickening or swelling of the endocardium itself; sometimes, also, as Bouillaud remarks, the adhesion of clots, resembling the buffy coat of blood, are among the anatomical signs of inflamed endocardium. The in- flamed endocardium is, according to Bouil- laud, more easily detached from the internal surface of the heart, owing in all probability to the subjacent cellular tissue having lost its force of cohesion, and become fragile. Lymph effused on the endocardium does not generally take the laminated form as in pericar- ditis, nor do we find it covering an extensive surface, as in that disease. Small patches of membranous lymph are sometimes met with here and there, either on the surface of the valves or over some part of one of the cavities; at other times it assumes a granular or warty form, or it projects in papilliform or conical or globular masses from the surface of the valve. Thus are formed the vegetations which are among the most frequent valvular diseases, and which offer the greatest impediments to the adequate action of the valves. When examined recently after their formation, they present all the characters of the album ino-fibiinous exuda- tions of serous membranes, their form being determined by the frequent changes of relation which the inflamed surface undergoes in the heart's action, as well as by the current of blood from the heart continually flowing over it. The further progress of inflammation of the endocardium induces thickening of the mem- brane or of the valves, organization of the effu- sed lymph, which thus becomes more firmly adherent to the surface on which it had arisen, and induration of the membrane from cartilagi- nous or calcareous deposits, which however are generally met with within the fold of membrane constituting the valves, and more intimately connected with the interposed fibrous than with the serous membrane. When inflammation of the folds of endocar- dium forming the valves runs its course with great rapidity, it may induce destruction of them to a greater or less extent. Softening, ulceration, and rupture of the affected valve are very speedily produced. " The ruptured and ulcerated portions," to borrow Dr. C. J. Wil- liams's description, " are found loaded with ragged, soft, fragile vegetations, more or less tinged with blood, and these are also some- times seen adhering to adjacent parts where the endocardium is entire. The remaining parts of the valves are much thickened and opaque yel- lowish white, with a pink hue; and pink patches are often seen in the aorta with atheromatous thickening." Sometimes a valve is perforated in its centre by ulceration, and the circumfe- rence of the perforation is surrounded by warty vegetations. It is well known that the endocardium of the left side is much more liable to disease than that of the right, whether as regards the valvu- lar portion of it or that which lines the interior of the heart. But the views of Bichat and others, who denied the occurrence of disease on the right side, have been abundantly refuted by modern observations. Chronic valvular diseases. — Chronic endocar- ditis affects the valves of the heart in such a manner as in all cases to occasion more or less obstacle to the flow of the blood from the ven- tricle or auricle. Sometimes, however, the disease is not of a kind to interfere with the valvular action and to permit regurgitation; but at other times the disease has gone so far in one or more of the valves as to prevent its con- tributing to the perfect closure of the orifice, and consequently to destroy the power of the valves to oppose regurgitation. Hence the subdivision proposed by Dr. Williams, for val- vular diseases, into those which more or less obstruct the current of the blood in its proper channel, or the obstructive, and those which permit it to pass in the reversed direction, or the regurgitant. Thickening of a valve, so as to prevent its complete apposition to the internal surface of the artery or of the ventricle, will oc- casion obstruction, the degree of which will depend on the degree of perfection of apposi- tion with which the valve may be applied to the neighbouring surface; on the other hand, the degree to which regurgitation is permitted will depend upon the degree of induration of the valve, and the want of extensibility which it manifests. Thickening of the edges of the valves is among their most common diseased states; the attached margin or base of the valve is also very frequently the seat of thickening, and in both these situations the fibrous tissue seems to be engaged principally in the disease. The inter- vening portion is generally affected as a conse- quence of the extension of the disease from these margins. In such cases the thickening arises from a deposit between the layers of the fold forming the valve; in other cases the thick- ening is produced by a deposit upon the surface of the valve. On the aortic valves this deposit, when on the ventricular surface, is apt to assume the form of two crescents corresponding in po- sition as well as form to the two crescentic por- tions of fibrous tissue within the fold of mem- brane by which the vnUe is formed. This fact ABNORMAL CONDITIONS OF THE HEART. 647 was, I believe, first pointed out by Dr. Watson. Ossification most commonly manifests itself in the fibrous zones which surround the heart's orifices, and therefore it is chiefly to be found at the bases of the valves ; but it likewise ex- tends towards their free margin ; and it too is apt to be developed in the double crescentic form in the aortic valves. Sometimes the ossi- fication appears to involve principally the mar- gin of the valve in whole or in part, and this occurs much more frequently in the semilunar than in the auriculo-ventricular valves. Osseous deposits in the valves are either in the form of thin calcareous lamina? or spiculoe, small round- ed points, or large masses more or less rounded, and often projecting to a considerable extent beyond the surface of the valve. The effect which the developement of these new deposits on or in the valves has upon their size and form, as well as upon the size and form of the openings which the valves surround, is very various and very interesting to the patho- logist. The almost invariable alteration which they produce in the size of the valve is to shorten it or dimiwsh it in depth ; the valve becomes corrugated\ its free margin thickened, or folded in the direction of the current, or in an opposite direction, the whole valve present- ing a curled appearance. The orifices are always more or less, diminished in size when one or more valves have acquired this rigid, inelastic, and contracted form ; the diminution is produced by the valve or valves always pro- jecting more or less into the orifice ; but the greatest degree of narrowing of the aperture is occasioned by the adhesion of two or more valves at their free margins ; and in this way, as may be readily conceived, an orifice be- comes sometimes almost completely obliterated. The same causes change the shape of the orifi- ces, and consequently we find altered size and shape constantly going together. It is in the left auriculo-ventricular opening that these changes are most commonly seen ; they rarely occur to so great an extent in the aortic orifice, and seldom at all in the apertures of the right heart. My friend, Mr. Adams, has made some most valuable remarks upon the contracted au- riculo-ventricular orifice of the left side, in his very valuable paper on diseases of the heart in the Dublin Hospital Reports. His description of the anatomical characters of the disease cor- responds so exactly with what I have many times witnessed, that I cannot refrain from quoting it. " When the dilated (left) auricle is cut into and cleared of the blood it contains, at its lowest part, instead of the mitral valve, a concave membranous septum of a yellow colour is seen, which is perforated by an oblong fissure, about half an inch in length, and one or two lines broad ; this fissure I have observed to be always obliquely situated, and to run parallel to the septum of the ventricles ; it ge- nerally is of a semilunar form, the concavity of the curve looking towards the root of the aorta, the convexity backwards ; the first formed by the larger portion of the mitral valve, the latter by the smaller ; the edges of this oblong fissure are generally studded with long depositions ; viewed from the left ventricle, the membranous septum is convex, and the angles of the fissure are connected by shortened chords tendineas, with two very thick fleshy columns, the one in front, the other behind." Dilatation of the valves. — We sometimes find the valves of the heart in a dilated or aneu- rismal state. Laennec has placed on record an example of this affecting the mitral valve ;* " A little pouch, half an inch long and more than four lines in diameter, projected on the supe- rior surface of this valve," i. e. into the left auricle. Mr. Thurnam has appended the detail of several cases to his memoir already quoted on Aneurisms of the Heart. f He de- scribes a specimen, preserved in the Hunterian Museum, affording an example of four aneuris- maj pouches of the tricuspid valve. The sime writer likewise records a case in which there was congenital absence of one aortic valve; the two, which were present, were thick and fleshy, and rough on their ventricular surfaces. The edge of the one was smooth, that of the other rugged ; there was a deposit of ossific matter at their points of attachment. From the ventricu- lar surface of the valve with the smooth border, there projected a little bag that would hold a swan-shot, and which opened by a little round mouth on the aortic surface of the valve. It had two little slits in its most depending por- tion, and was evidently formed by a dilatation of the valve itself." Atrophy of the valves. — We have a familiar instance of atrophy of valves in the case of the Eustachian valve, which undergoes as it were a sort of natural atrophy from the commencement of extra-uterine life. The valve becomes cri- briform, and the holes by which it is pierced gradually enlarge and coalesce, and in this way the valve is worn away. We often find one or more of the semilunar valves perforated by openings of a similar kind, without the co-ex- istence of any other disease ; the margin of the opening is always smooth, and the valve itself thinner and more flaccid than is natural. Ac- cording to Dr. Williams, the wasting affects the posterior portion of the mitral valve, " the membrane of which is often annihilated by it, the cords being inserted directly into the auri- cular ring." The anterior lamina is also occa- sionally found much shortened, and without those fine thin expansions of membrane which commonly unite the cords to each other, below their insertion into the thicker part of the valve. .Entozoa in the heart. — The occurrence of entozoa in the human heart must be considered to be extremely rare, at least the cases on record which may be depended on are very few. Andral states that he found the cysticercus once in the human heart, but has seen it fre- quently in the hearts of measly pigs. Many examples are mentioned by various authors of ascarides, filaria?, cercariae, and other entozoa in the hearts of dogs and many other of the in- * Quoted in Bouillaud's work, t. ii. p. 510. t Log. cit. 648 ANIMAL HEAT. ferior animals, Mammalia, as well as birds, reptiles, and fishes.* States of the blood in the heart after death. — "What appears to be the natural state of the contents of the heart after death is as follows. The right auricle contains a coagulum of dark fclood, and the right ventricle contains a similar one, of less size ; a very small quantity of coa- gulum or of fluid blood is found in the left cavities, and it is not uncommon to find a coa- gulum extending into the aorta ; white coagula are often found in these cavities. Sometimes these coagula, especially at the right side, adhere closely to the wall of the cavity in which ihey are situated, and appear as it were moulded upon it, sinking into the interstices between the fleshy columns, so as to render it difficult to remove them. The modification which we most frequently meet with in this state of the heart's contents, is that in cases of asphyxia; affording, however, merely an in- stance of aggravation, if I may so speak, of the natural state ; the right cavities and the vessels leading to and from them are gorged with dark blood, liquid or coagulated, while the left cavi- ties are nearly empty. Such states of the heart's cavities, it is obvious, are formed in articulo mortis. Fibrinous masses, either mixed with or deprived of the colouring matter of the blood, have been many times found, which it cannot be doubted were formed in the heart some time prior to death, and probably gave rise to symptoms of a serious nature; these are the true polypous concretions of the heart. The manner in which Mr. Allan Burns, one of our earliest British writers on the heart, explains the formation of some of these concretions, is deserving of attention. " If," he says, " we strictly scrutinize all the reputed cases of poly- pus in the heart, we shall reduce the real ex- amples of this affection to a very limited num- ber indeed. Still we shall leave a few, where there is reason to believe that the concretion had been formed a very considerable time be- fore death : but it must be understood, that these concretions are seldom found except in hearts otherwise diseased. In health, the blood does not tarry for any length of time in either the heart or vessels; it is incessantly in motion, circulating with greater or less rapidity, accord- ing to the state of the heart and arteries. The blood never in health remains so long in con- tact with the surfaces of the heart, as to allow of its being changed by their action. In some diseases of this organ, irregular actions are ex- cited by very trifling causes ; the blood stag- nates longer in the heart than it usually does or ought to do, while here it undergoes changes by the reciprocal action of the blood on the heart and the heart on the blood ; new organized matter is deposited, and adheres to the parietes of the cavity in which it is lodged. This con- cretion slowly increases, the first panicle acting as the exciting cause for the deposition of the second, and so on." The strongest evidence of the formation of * For a list of the references to such cases, see South's edit, of Otto, Path. Anat. p. 293. such coagula some time before death consists in their being organised : in a case recorded by the writer from whom the preceding passage was quoted, a large and fully organised polypus was found in the right auricle ; its attachment was by a rough surface to the musculi pectinati, and its body hung down into the right ventricle. It very much resembled a nasal polypus, and it was so firmly fixed to the heart, that it allow- ed the whole mass of the heart and a consider- able portion of the lungs to be suspended by it, without showing any tendency to separate. It was pendulous and tapered from below up- ward ; its structure was dense and lamellated, and not a single red globule entered into its composition." In this casp, as in other similar ones quoted by Andral, the adhesion of the po- lypus seemed due to an inflammation of the endocardium, either excited by the contact, or before the formation of the coagulum. That such coagula may be permeated by bloodves- sels is proved by the cases of Bouillaud and Rigacci, quoted by Andral : in the latter cases, these reddish filaments passed from thecolumna: carrteae and entered the substance of the poly- pous mass : they had all the appearance of bloodvessels, and when injected with mercury were found to divide into a number of small branches that ramified through the substance of the polypus. By careful dissection it was as- certained that the tumour was formed altogether of a mass of fibrine, such as is found in the sac of arterial aneurisms Pus is occasionally found in the centre of these fibrinous concretions, but whether carried to the heart in the blood, and accidentally enclosed in the coagulum during its solidification, or formed in the coagulum by some action within it, it is impossible to decide. Osseous and cartilaginous deposits toohave been found in them, as in the case from Burns, in which one of these polypi was ossified in several points, and so perfectly organized that on inflat- ing the coronary vein, a number of minute ves- sels on the surface and in the substance of the tumour became distended with air. (R. B. Todd.) HEAT, ANIMAL.— Judging merely by our sensations, we should infallibly conclude that our bodies undergo very considerable changes of temperature. This belief was in- deed necessarily entertained previously to the time when natural philosophy had discovered a means of ascertaining the true state of the matter. The application of the thermometer has dissipated the error. But then error of an opposite kind was run into, and the results of a very limited number of observations led men to conclude that the temperature of the human body was invariable or nearly so. Still the measures of temperature given by different ob- servers did not perfectly accord, though each presented his conclusions as the temperature of the race. It was but reasonable to imagine that these discrepancies arose not from any want of accuracy in observation, but from diversities inherent in the subjects observed. This is now known to be the case. But though proofs of this truth have been greatly multiplied, the ANIMAL HEAT. 649 whole subject has never been presented in a connected and systematic manner. Since it is proved that the temperature of the human body varies, we can only obtain an approximation to its actual amount by taking the mean of all the good observations that have ever been made, being particularly care- ful to include the extremes ; for a mean gives but a very imperfect idea of a term that ought to represent a variable number, if the limits are not at the same time assigned and taken into the account. The best observations of this kind, provided they be sufficiently numerous, will be those that have been made by the same individual, inasmuch as there is great likeli- hood that he will always have made use of the same procedure and of the same instruments, by which the results become more readily com- parable one with another. Temperature of the human eody. — In the following obseivations we shall make use of the measures of temperature given by Dr. John Davy. These amount to one hun- dred and fourteen in number, and were made on individuals of both sexes and of different ages in three quarters of the world, in Europe, Asia, and Africa, in different latitudes, under various temperatures, and among individuals of different races. But, as the knowledge of the mean and extreme temperatures of the body of man would have little value apart from the statement of the circumstances and conditions under which they were ascertained, we shall at the same time give the ages of the subjects and the temperature of the air at the time of the observations. The mean age of the subjects of Dr. Davy's observations was twenty-seven years. The mean temperature oftheairwas 23°, 3 c. (74° F.*) be- tween the limits of 1.5°, 5 (60° F.) and 27°, 8 (82° F.). In these circumstances the mean temperature of the body, which was always taken in the mouth, was 37°, 7 (100° F.) be- tween the extremes 35°, 8 (96°, 5 F.) and 38°, 9 (102° F.). The greatest difference in one hundred and fourteen observations, there- fore, scarcely exceeded three degrees. The temperature of the human body thus obtained might be considered as exact if the conditions of age and external atmospheric temperature approached pretty closely to their respective means. This, in fact, was the case as regards the first term, but not as concerns the second ; for some of the observations were made under very intense degrees of heat, such as 27°, 8 (82° F.), but none at the opposite extreme, or at a temperature which could be reputed cold, a temperature of 15° (59° F.) being already suf- ficiently agreeable. So that if the temperature of the air influences that of the body, a ques- tion which we shall examine by-and-by, the mean which we have stated as the temperature of the species would be too high. It is of some consequence to pursue * [The valuations according to Fahrenheit's scale the editor desires may be regarded as mere though close approximations to the indications according to the centigrade scale.] — Ed. these inquiries among the lower members of creation, among animals ; and the writer to whom we are indebted for the observations quoted upon man has also made a great num- ber upon the lower animals. We shall there- fore continue to make use of this series of experiments, as we have already made use of that which bore upon man individually. Temperature of the Mammalia. — The observations here were made on thirty-one dif- ferent species taken from among the principal divisions of this class, and under a mean tem- perature of the external air equal to 25° (77° F.), between the limits of 15° (59° F.) and 30° (86° F.). The mean temperature of the body of the Mammalia was 38°, 4 (101°, 10 F.), the max- imum being 40°, 5 (105° F.), the minimum 37°, 2 (99° F.). The extent of variation Con- sequently presented by the Mammalia, 3°, 3 of the centigrade scale (6° F.), is nearly equal to that exhibited by man. But there is this difference between the two scales, that the extremes and the mean in the case of man are inferior to the corresponding terms in the case of the Mammalia. Temperature of Birds. — The observa- tions here were made on fifteen species in different orders. The mean temperature of the air was 26°, 1 (79° F.), between the extremes 15° (59° F.) and 31°, 5 (88°, 75 F.). The temperature of the subjects of the experiments offered a mean of 42°, 1 (107°, 86 F.), the su- perior limit being 43°, 9 (111° F.), the inferior 37°, 2 (99° F.). The temperature of birds, therefore, presents a scale much more exten- sive than that of man and the Mammalia, amounting to as many as 6°, 7 degrees centi- grade (12° F.). It also stands above both of the others in the point of its mean, which is higher by 3°, 7 (6° F. nearly) in its upper limit, and 5° centigrade (about 9° F.) higher in its lower limit. The lower limit, in tact, corresponds very nearly with the mean term of the heat of the Mammalia as exhibited in the preceding scale. But in neither scale can we say much in regard to the inferior limit, inas- much as no observation was taken at a tem- perature lower than that of fifteen degrees cen- tigrade (59° F.). When we compare the preceding statements of the temperature of animals, it is apparent that it varies but little between one species and another of the same class. In passing to dif- ferent classes, however, the difference becomes very considerable, and though the observations are here much fewer in number, they are per- fectly satisfactory as regards the general result. Temperature of Reptiles. — From nine observations made on members of the four orders of Reptiles, Dr. Davy found, the ex- ternal air having a mean temperature of 26°, 5 (79°, 75 F.) between the extremes 32° and 16° (89°, 5 and 60°, 75 F.), that the temperature of Reptiles was not higher than 28° (82°, 5 F.). Temperature of Fishes. — If from Rep- tiles we pass to Fishes, corresponding and even more remarkable differences are perceived. Dr. Davy, indeed, gives the temperature of 650 ANIMAL HEAT. no more than five species, but they belonged to very different orders. The mean external temperature being 22°, 3 (72°, F.), that of fishes was found to be but 23°, 2 (74° F.), which is very little more than one degree cen- tigrade higher. This difference becomes even more striking, if possible, as we descend in the scale of animals. Temperature of Insects. — From eight observations on Insects of very dissimilar spe- cies, the mean temperature of the air being 24° (75°, 5 F.), that of the insects was 24°, 2 (75°, 75 F.) Temperature of the Crustacea. — Two species of Crustaceans, the cray-fish and crab, presented a still more interesting phenomenon. The mean temperature of the air was 24°, 4 (76° F.) at the time of experimenting, that of the Crustacea 24°, 1, or somewhat lower than the ambient medium. This we do not presume to present as the rule, but we would say that the temperature of the Crustacea is nearly equal to that of the medium in which they are plunged. Temperature of the Mollusca. — In observing the temperature of a single Mollusc, the common oyster, the temperature of the sea being 27°, 8, (82° F.) that of the animal was 27°, 8 also. It is obvious, therefore, that the differences in the temperature of animals from reptiles inclusively downwards is very inconsiderable. All these animals, indeed, may he united under a single category, and regarded as con- stituting a single group characterised by the state or degree of their temperature. The same may also be done with reference to the animals of the two higher classes, Mammalia and Birds, which in point of temperature are so nearly akin to each other. There are consequently two grand divisions of animals as regards temperature ; the one comprising the Mammalia and Birds ; the other including Reptiles, Fishes, Insects, Crus- taceans, and Molluscs. The first is known under the name of warm-blooded animals, the second under that of cold-blooded animals. To characterize the first under the view of temperature, the mean of the temperatures of the respective classes which compose it must first be taken. From the experiments of Dr. Davy the mean temperature of Mammalia ap- pears to be 38°, 4 (101° F. ) that of birds 42°, 1 (108° F. ) Mean of both classes 40°, 25 (104°, 5 F.) We may therefore say that the mean tempe- rature of warm-blooded animals, including man, surrounded by a moderate external tem- perature is in round numbers 40° (104 F.) between the limits of 36° and 44° (97° and 111°, 5 F.), by which we have a scale of dif- ference amounting to 8° (about 14° F.). The other class, that, namely, including the cold-blooded animals, having no peculiar tem- perature proper to them, may be characterized in the following manner: — their temperature differs little or not at all from that of the sur- rounding media in which they live, when this is at a degree which may be called moderate; so that the differences are either inappreciable, or do not exceed the limits of + 4 (39°, 50 F.). We shall return by-and-by upon this character, which requires development. General conditions of organization in relation with the production of a greater or less degree of heat. So wide a difference in the heat of the two categories of animals might lead to the pre- sumption that there is also a very great dif- ference in point of structure. If, indeed, this relation exists and is easily detected, we may be led to discover the general conditions of organization upon which the production of heat depends. Is there an organization com- mon to Mammalia and Birds, distinct and different from that belonging to the other classes of animals ? This question can be an- swered in the affirmative : there is a well-marked diversity of organization which distinguishes Mammalia and Birds from all other animals. I. The most prominent feature of diversity exists in the sanguiferous system, which is divided through its entire extent into two dis- tinct parts without direct communication be- tween them, the heart presenting a complete median septum, the bloodvessels in like man- ner forming two systems of canals, which have also no immediate communication in their trunks. II. This peculiarity of structure, which is only met with among animals having warm blood, is regularly associated with an organ adapted for aerial respiration. The character which distinguishes this respiratory organ from the one met with among cold-blooded animals, reptiles especially, is this,- — that either in itself or its appendices (the air-sacs of birds) it pre- sents a much larger extent of surface in relation with the air. III. Warm-blooded animals are farther dis- tinguished from the cold-blooded by important modifications of the digestive canal. 1. The first portion of the apparatus from the mouth to the stomach is much more complex in them; for instance, it presents either a much more perfectly developed dental system, fitted to divide the food, or a sac, as among birds, fitted to macerate the aliment, and cause it to undergo a kind of preparatory digestion before it is passed to the stomach. 2. The stomach is more distinct; either the entrance to and exit from this pouch are better marked, being often provided with a valve, as in the Mam- malia, or its structure and form are more spe- cial, as we observe it among Birds. 3. The intestinal canal is much longer in the warm than in the cold-blooded tribes. IV. The nervous system presents diversities still more important and well-marked. The most striking character exists in the proportion of the principal trunk of this system, and especially of its encephalic extremity, which is much larger in the warm than in the cold- blooded animals. The most remarkable structural conditions ANIMAL HEAT. 651 of warm-blooded animals, then, are four in number, three of which are referable to the organs of nutrition, the fourth to the nervous system, which may be briefly related in the' following order: — 1. higher complication and greater extent of the digestive apparatus; 2. entire separation of the circulating apparatus into two systems, the venous and arterial, with- out direct communication between them; 3. organs of aerial respiration presenting a much larger surface to the contact of the atmosphe- rical air; 4. a nervous system of which the axis, and especially the encephalic extremity, bears a very high ratio to the whole. These structural characters determine the following modifications of function. 1st, The complexness and greater extent of the di- gestive apparatus in warm-blooded animals produces a more perfect elaboration of the matters which serve for the formation of blood. 2nd, The arrangement of the parts of the cir- culating system maintains the arterial blood quite distinct from the venous, and in a state of complete purity. 3rd, The respiratory ap- paratus, by the great extent of its surfaces in contact with the air, secures that its distinguish- ing qualities be imparted in the highest pos- sible degree to the arterial blood, which more- over is elaborated in larger quantity. The predominance of their nervous system, and es- pecially of its encephalic extremity, renders all the parts of the body much more excitable, and gives the greatest energy to the nutritive functions. The whole of these organic condi- tions are mutually dependent, and may be reduced to the expression of these two general conditions: — -1st, the formation and distri- bution of the arterial blood, the particularly exciting and nutritive blood of the body ; 2nd, the most powerful influence of the nervous system. As these characters of primary significance in the animal economy coincide in Mammalia and Birds with the greater production of heat, and thus distinguish them from all other ani- mals, it is probable that between these organic conditions and caloricity or the power of evolving caloric, there is a relation of the na- ture of cause and effect. It is even almost impossible that this should be otherwise than as it has been stated ; for the characters of organization and the peculiarities of function, coincident with the greater evolution of caloric, are almost the sole points of any importance that distinguish warm from cold-blooded ani- mals. It is therefore nearly certain that the condi- tions requisite to the production of heat must exist within the circle of the functions which we have described. And if this relation do actually exist — as these functions are in a state of mutual dependence, — it follows that one of them cannot be modified, the others remaining, so to speak, in the same condition, without modification resulting in the calorific capacity likewise. It is of great consequence to verify this assumption, because if it be well-founded, the probability already elicited of the power of engendering heat being de- pendent on the state of the functions in the relations which have been indicated, becomes matter of certainty. So that it is of the highest import to follow the modifications of these functions presented by animals and man in order to compare them with the respective varieties of calorific power presented by each. And if we find that they coincide, and accord with the principle established, we shall have discovered the conditions of organization and of function upon which the production of ca- loric depends. Conditions of organization and of func- tions may be entitled the physiological causes of the production of animal heat. If we succeed in determining these, we ought to rest satisfied. If, indeed, to this knowledge we could add that of the immediate cause of this phenomenon among animals, or what is the physical cause, it would be a great gain for science. This, accordingly, was the ob- ject of the labours of the majority of phy- siologists who have given their attention to the subject of animal heat. But they could not possi- bly succeed in their researches, for the simple reason that natural philosophers themselves have not yet discovered how heat is produced in the inorganic world ; although indeed they have presumed that they were acquainted with it. It is not to be wondered at, then, that attempts have been made to detect this presumed cause amidst the complicated phenomena of life. But natural philosophers have lost confidence in the theory which they had formed, and are searching for a new one. Meantime they are doing what ought always to be done under such circumstances ; they are studying with care the various conditions and circumstances in which it is produced ; determining these with precision, and measuring with rigour the quantity of heat produced. Of late, therefore, many distinguished physiologists have entered on the same path, and by experiment have endeavoured to ascertain the physiological con- ditions of the production of heat. But if their predecessors have not attained the object they had in view, they have nevertheless ren- dered very essential services to science ; for in searching after the physical cause of heat, they have determined with precision the physiological conditions of the production of animal heat, which are of very great importance. Inde- pendently of the simple observation of the actual temperature of animals, the labours of physio- logists on this subject consist almost entirely of experimental facts, that is to say, facts created by science. But there is one source of inquiry into the laws of animal heat which has been little dipped into, although it is beyond all comparison the most abundant. I allude to that presented to us by nature in the all but infinite variety of modifications of organization and pheno- mena exhibited in the vast chain of animated things, not only in the diversities of species, but also in the varieties of age and constitution, and the changes induced by the states of health and disease. In making this an object of peculiar study, we become acquainted with 652 ANIMAL HEAT. the greatest possible number of phenomena connected with animal heat ; and in determin- ing the physiological conditions of its produc- tion, we shall lay up a store of theoretical knowledge peculiarly applicable to practice, the end and object of all physiological inves- tigation. The means of comparing these modifications, however, and of judging of their importance are not always easy. We shall do as much as the actual state of our knowledge permits if we inquire first, by what means we can ap- preciate the modifications relative to the arterial blood. 1. As regards the quantity of the arterial blood, we shall view this point of the inquiry less with reference to the whole amount of blood circulating in the body, than to the quantity which is formed at a time, as it were, in the lungs; because it is evident that if the arterial blood influences the phenomenon of heat, the more that is formed at any given time the greater ought to be the direct or in- direct influence upon the production of heat. a. As it is not always possible to have a direct and precise measure of the relative quantity of blood in the organs, we must be content with an approximative mode of estimating this, which consists in ascertaining in what degree the lungs are loaded with blood, b. Anaid to the judgment may also be derived from the relative size of the lungs, the tissue being presumed to be nearly alike throughout their entire mass, c. With an equal volume of lungs, the greater or less compactness of the tissue must be taken into the account. The closer the tissue is, the more are the surfaces in contact with the air multiplied, d. The extent and rapidity of the respiratory motions form another element in the calculation; for to increase the amount of relation with the air is analogous to the for- mation of a larger quantity of arterial blood within a given time. All the foregoing data refer to the absolute or relative quantity of arterial blood. But there are other particulars connected with its constitution which it is necessary to mention. The blood, for instance, is composed of a fluid and solid part, the latter existing under the form of globules. It is obvious that the fluid is not the characteristic part of the blood, in- asmuch as this is met with elsewhere, whilst the globules of the blood are only known as constituents of this fluid. The arterial blood consequently ought to have qualities by so much the more distinctive and energetic as it con- tains a larger proportion of globules. Now this is a character that may be appreciated with exactness, and measures of it have been given. But the globules of the blood are not in- variably of the same nature, a fact which may be judged of by outward and very obvious and appreciable characters, namely, size and form. The smallness and more or less perfectly sphe- rical or rounded form of the blood-globules distinguishing animals with warm blood, co- incide in the Vertebrata with a higher capacity to produce heat. For we do not institute this comparison here save in reference to animals included in this division, inasmuch as the cha- racters of the blood have only been studied under these relations among them. We shall, therefore, hold the energy of the calorific power to be connected with the smallness and rounded form ot the globules of the blood in vertebrate animals. 2. The materials of the blood being sup- plied by the digestive apparatus, we might judge, all things else being equal, of the per- fection of the blood by the perfection of this apparatus. But there is likewise a necessary co-relation between the result of the function, and the aliment; for instance, when the ap- paratus shall be found nearly alike in any two cases, the difference of food necessarily in- fluencing the qualities of the blood, the com- parison must be established, every other cir- cumstance beins; equal, according to the higher or lower nutritive qualities of the food. As the use of the arterial blood is to excite and nourish the different parts of the body, there will be a necessary correspondence be- tween the blood and the result of the nutrition which may become manifest in the nature and quality of the tissues. And in this case it would be fair to make use of these characters of tissues to form an estimate of the nature of the blood in reference to its aptitude to pro- duce heat ; and this we shall accordingly do. But even in the event of all these characters failing us, there is another source whence we can derive comparative measurements, which are susceptible of very rigorous application. Since it is necessary that the venous blood should pass through the lungs in order to be- come arterial from contact with the air of the atmosphere, it is obvious that it cannot un- dergo any change in its constitution without the air at the same time suffering a change. That the air is altered by the respiratory act is well known to all, and as there is a necessary co-relation between the blood aerated during respiration and the air which it alters, the amount of alteration undergone by the one may be estimated from the change suffered by the other. The quantity of air altered by re- spiration, all other things being equal, ought to be found in relation with the production of heat. The different characters which we have men- tioned all refer directly or indirectly to the blood. There still remains one of another order which may also serve us as a guide in making comparisons in reference to the pro- duction of heat. The allusion here made is to the nervous system, the superior value of which in warm-blooded animals has already been commented on. It is thus, then, that we may assume the predominance of the nervous axis, and particularly of its encephalic ex- tremity, as a condition favourable to the pro- duction of heat, and which, in circumstances of parity among the other conditions, must tend to the production of a greater quantity of heat. Such are the modes of proceeding which we shall follow in investigating the modi- fications of the organic conditions and of the functions which coincide with the greater evo- ANIMAL HEAT. 65 lution of heat. To ascertain whether this coincidence is to be viewed as being in the mutual relation of cause and effect, it imports to know whether or not their variations are in relation with those of the heat produced. If they coincide whenever we compare them, pro- vided these comparisons are but sufficiently numerous, we shall be safe in admitting a necessary connexion between them. We were led to the relation which engages our attention in the course of our comparisons of warm- blooded animals with those having cold blood considered in general. Let us now enter upon a comparison of the same kind, but more par- ticular, whilst we take account of the most important subdivisions of these two great groups in order to verify our first inductions. We shall first compare Mammalia and Birds to determine which of the two classes, in con- formity with the principle to which we have been led, has its organization most favourable to the production of heat. The lungs of Birds, although smaller, are more loaded with blood than those of the Mammalia, and are in communication with ex- tensive air-cells, spreading all through the body and even penetrating into the cavities of the bones, so that the air may be said to penetrate the body generally, and to be in contact with the ramifications of the aorta as well as with those of the pulmonary artery ; the blood of these animals is therefore in the most extensive rela- tion imaginable with the air of the atmosphere. Again, if the nature of the blood of Birds be considered, independently of this extensive relation with the air, the organic condition here will not appear less favourable to them. The globules of this fluid, indeed, are a little larger and less spherical than in Mammalia, which is a disadvantage ; but the proportion they bear to the fluid part is so favourable to Birds that this circumstance must give them immensely the advantage in reference to the character which engages us. With regard to the nervous sys- tem, if the encephalic extremity is developed in a minor degree in Birds, their circulating and respiratory systems act with greater quick- ness. Lastly, and as an effect of the whole of these conditions, the consumption of air is much greater among Birds than among Mammalia. From all that precedes, it follows, if the principles already laid down be correct, that Birds ought to produce the greatest quantity of heat; and this is actually the case, as we have seen when we were speaking of the actual tem- peratures of the different classes of animals — the mean temperature of the Mammalia is 38°, 4 (101° F.), that of Birds 42° 1 (108 F.). Here, then, is a powerful confirmation of the relation which we have recognized betwetn the conditions of the organization and the produc- tion of heat; it is of so much the more value as the relation being based on the comparison of two classes so numerous, the verification is made on a scale of proportionate extent. We shall extend it still farther by contrasting in the same manner the two other classes of the Ver- tebrata, Reptiles and Fishes. I. The organs which prepare the materials of the blood — the digestive apparatus is more complete among Reptiles than among Fishes; 1st, in the dental apparatus when it exists; 2d, in the more distinct stomach; 3d, in the greater length of the intestines. II. The blood of Reptiles is superior to that of Fishes both as regards the nature of the globules and their relative proportion, their size being smaller, and their numbers greater, than among Fishes. If the whole of the blood in the Reptile is not transmitted through the organ of respira- tion, whilst in the Fish it is, a larger quantity of this fluid is brought into contact with the air in the same space of time in consequence of the greater extent of surface of the organ in the Reptile, and then the Reptile has the farther immense advantage of a pulmonary or aerial respiration, whilst that of the Fish is branchial or aquatic. To conclude, the nervous system of Reptiles is much more developed in the cerebro-spinal axis, and especially in the ence- phalic extremity, than in Fishes. From this comparison it follows that the organic and functional conditions, judging of these in conformity with the principles which we have taken as our guide, are much more favourable to the development of heat in Rep- tiles than in Fishes. This theoretical deduction is fully confirmed by direct observation, as we have seen above, and this verification becomes a new confirmation of the accuracy of the prin- ciple. We continue to pursue this parallel by a summary comparison of the organization in its relations with the production of heat in the cold-blooded Veitebr-ata and the Invertebrata generally. A glance suffices to shew the vast inferiority of the Invertebrata in this as in every other respect. In the first place their blood is so little of the same nature as that which has been recognized most favourable to the produc- tion of heat, that it wants the characters whe- ther of arterial or of venous blood. The blood of the Invertebrata, with the exception of a very small group (the worms with red blood), is colourless. In the structure and number of its globules it is also greatly inferior. The globules, indeed, may be smaller, but then they are of a much more simple structure, and con- sequently lower in the scale, in other words more imperfect. In the relation to the fluid part of the blood too, they are in much smaller proportion than among the Vertebrata. An analogous character is manifest in the tissues generally, the proportion of water in them being incomparably larger in the Inverte- brate than in the Vertebrate series of animals. Finally, there is an immeasurable inferiority in the nervous systems of the Invertebrate com- pared with even the lowest of the Vertebrate series of animals. Ftom all this it results, agreeably to the principle of which we are now showing the application, that the Invertebrate ought to have a much smaller capacity of producing caloric than even the cold-blooded Vertebrate animals; and this is exactly as we found matters to be by direct experiment in regard to the tempera- 054 ANIMAL HEAT. tore of the different classes, the results of which have been already stated. The comparison might be carried out in regard to Insects and the Mollusca, which present some appreciable differences. If attention were confined solely to the structure of the greater number of the organs of nutrition, which are much more largely developed in Molluscs, it might be inferred that they had a higher calorific power than Insects; but when we take into the account, 1st, the final result of the nutritive functions, the quality of the tissues, which in the Mollusc are much more loaded with watery fluid, by which they acquire a greater degree of softness and flaccidity, (whence the class has its name,) whilst in the Insect they are, on the contrary, as remarkably dry and firm ; — 2d, when the most general mode of respiration is compared in the two divisions, it being in the Insect aerial, in the Mollusc aquatic ; 3d and lastly, when we glance on the one hand and on the other at the state of the nervous system, and observe how much less perfectly this is developed in most of the Molluscs than in the Insect, it is impossible not to perceive that according to the principles influencing the production of heat, the Mollusca must be inferior in this respect to Insects. This is indeed the result of obser- vations of all kinds, however imperfect or limited these may have been, as we have seen above. It is impossible to carry the comparison further; the phenomena connected with heat in the lower grades of the animal creation become inappreciable ; and this even in virtue of the same principle that has been an- nounced ; for the tissues are found to become more and more watery as we descend in the scale, till at length the solid constituent is almost inappreciable. Of course the circulating fluid must be watery in a still greater ratio; it contains but few globules; and then the ner- vous system falls off in a still greater propor- tion ; it becomes more and more imperfect, till at length no trace of it is to be discovered. We thus arrive at the last links of the chain, after having run over the whole animal king- dom, and we have found one uniform principle of correspondence between organic modification and calorific power. It were difficult to imagine any more satisfactory proof of a principle than has been afforded ; indeed as this has on no one occasion been found belied, we are fully authorized to regard it as established. We have as yet examined but two points in reference to animal heat; 1st, the temperature of man and of the different classes of animals; 2d, the general relations of organization with the production of heat. In mentioning the temperature in any case, we have spoken of it as determinate ; and farther, to have data that should be always comparable, the tempe- ratures have been taken regularly in the same places, — viz. the mouth m man, and the other extremity of the intestinal canal in animals. We have still to ascertain whether the tempera- ture varies or is identical in different parts of the body. Temperature of different parts of the body. — There is no need of the thermometer to tell us that all parts of the body do not at all times preserve the same temperature. We are often certain that the extremities are colder than the trunk for example; and a law of decrease of temperature in the ratio of the dis- tance of parts from the heart had even been deduced from this observation. But when exact measurements came to betaken, this law was soon found to be at fault, as will be seen by-and-by in the course of these observations. Dr. Davy, in taking the temperature of the different parts of the body of a lamb, found that of the right ventricle of the heart 40°, 5 (106° F.), that of the left ventricle 41°, 1 (106° F.). The left ventricle was therefore higher in temperature than the right to the extent of a degree of the scale of Fahrenheit's thermometer. The temperature of the rectum corresponded with that of the right ventricle. In my inquiries along with M. Gentil into the relations in point of temperature of certain external parts, we found in a strong man, perfectly at rest in mind and body, in the month of July, the external air being at 21°, 25 c. (71° F.), the temperature of the mouth 38°, 75 (102° F.) ; that of the rectum corresponded. The hands presented the next highest degree, marking nearly 37°, 5 (99°, 5 F.). What is remarkable is that the axillae and groins, which corresponded with one another, were very sensibly lower in temperature than the hands ; they did not raise the thermometer higher than 36°, 90 c. (99° F.). The cheeks marked 35°, 93 (90°, 5 F.), the temperature being ascertained by enveloping the bulb of the thermometer in the skin of these parts. The feet were a little lower, 35° 02 (about 90° F.) ; their temperature being deter- mined by placing the thermometer between the two, so that the bulb was surrounded on every side. The temperature of the feet was, there- fore, notably lower than that of the hands, differing to the extent of 1°, 88 of the centigrade scale (above 3° of Fahrenheit's thermometer). Placed on the skin between the thorax and abdomen the thermometer was at its minimum, not rising higher there than 35° (95° F.); but here a part of the bulb being in contact with the air, there must have been considerable cooling. As the question here is not of absolute but merely of relative temperatures, we can make great use of the results come to by the different writers quoted. We shall present a summary of these under the following head. Relations between the temperature of inter- nal parts. — 1st. The warmest part of the body, according to John Hunter, is in the abdomen close to the diaphragm. 2d. The next part in point of temperature is the left ventricle of the heart. 3d. The right ventricle of the heart is the next in succession. The rectum and the mouth shut are of the same temperature. The greatest difference consequently between the temperature of these internal parts does not amount to more than 1° centigrade, or at the utmost 2° Fahrenheit. Supposing the relations in temperature of the ANIMAL HEAT. 655 internal parts to be pretty constant in the normal state, the temperature of the right ven- tricle of the heart and of the rectum may be determined by taking the temperature of the closed mouth ; that of the left ventricle will be found by adding 0,44 c, or 1° F., to the degree indicated. Relations in point of temperature between external parts. — We have only data for insti- tuting comparisons in regard to the hand, the axilla, the groin, and the feet among the external parts of the body. In a moderate summer-heat die hand appears to be the part which is most susceptible of showing a high, the feet the parts most susceptible of exhibiting a low temperature. The axilla and groin gene- rally exhibit nearly the same degree of tempe- rature; and the amount in which they differ in this particular from the mouth may be stated at about 1°, 75. When we direct our inquiries with a view to ascertaining any general relation in the tempe- ratures of different parts of the body, whether external or internal, we soon discover, as has been already stated, that this has no connexion of an inverse kind with their distance from the heart. At the same time there is a general condition discovered influencing the tempera- ture of the different parts. This is their situa- tion in reference to the surface or inside of the body. The temperature is higher, for instance, within the trunk than on its outside. What- ever other reason may be assigned for this, there is one which is purely physical, that must influence it powerfully. It is obvious that the surface of the body and limbs must cool much more rapidly than the interior of the body. So that, supposing the temperature at first to be every where uniform, the difference in the rate of cooling would very soon suffice to cause a notable reduction on the exterior beyond that which took place in the interior of the body. This cause, however, can only be charged with its own share of influence ; there are others which must act with considerable effect, and among these especially the one upon which the production of heat depends. We have seen that the condition of the functions of nutrition most closely in relation with animal heat was connected with the arterial blood. Now inas- much as the arterial blood is that which is most intimately connected with the production of caloric among animals, we might fairly expect that the temperature generally would be rather above that of the venous blood. And we have seen that there was actually a difference be- tween the temperatures of the two ventricles, that of the left being the higher. Experiment has also shown that there was a corresponding difference in the temperatures of the two kinds of blood circulating in the arteries and veins ; arterial blood is actually higher in temperature than venous blood to the extent of a degree of Fahrenheit's scale. We shall add here, and in conformity with the same principle, that it is to this difference of temperature of the two kinds of blood that the difference in the tempe- rature of the right and left ventricle of the heart is owing. We need not be hindered in adopt- ing this conclusion from the circumstance of the blood of either ventricle being found in a slight degree inferior in temperature to the ven- tricle itself, inasmuch as the blood abstracted from the canals that contain it, and exposed to the air, begins to evaporate, and loses heat ra- pidly. Nevertheless it is not demonstrated that the difference in temperature of the blood out of and of the blood in the ventricles of the heart depends on this cause. There may be another at work ; the influence of muscular contraction for instance, a point which we shall examine generally by-and-bye. New means of estimating variations of temperature have been lately discovered, by which changes that en- tirely escaped us as judged of by the thermo- meter are made abundantly obvious; by which, indeed, the temperature of parts inaccessible in their natural and normal condition to the ther- mometer are now investigated without diffi- culty. In using the thermometer as the means of estimating temperature, it is evident that this instrument could not be introduced into the external parts without injuring the tissues, without incisions, &c, which would necessarily alter them materially, and produce so much dis- turbance in their functions, that an increase or diminution of temperature must almost neces- sarily have been the consequence. The ther- mometer, besides, however small its dimen- sions, has the inconvenience of always either absorbing or giving out a considerable quantity of heat according to circumstances, before it gets into equilibrium with the parts with which it is brought into contact. A necessary fall or rise in the absolute temperature of these parts is the natural consequence of this. Further, the thermometer is incapable of showing sudden variations in temperature; several minutes must always elapse before it gets into a state of equi- librium in regard to temperature with the parts or medium surrounding it. If a thermometer, for instance, be placed in the mouth, three or four minutes must elapse before it will cease to show any increase of temperature. Now if any calorific phenomena of short duration were de- veloped in that time, it is evident that all idea of their occurrence would escape us. These considerations led to the adoption of thermo-electrical means by Messrs. Becquerel and Breschet. The processes they employed in procuring indications of temperature were the following. The only means we have of pe- netrating into the interior of organs without in- jury is to make use of a needle similar to that employed in acupuncture. Now it is easy to arrange this needle so as to obtain thermo-elec- tric indications, which proclaim immediately and with the greatest precision the temperature of the part or medium with which the point happens to be in contact. It is enough to compose this needle of two others in metal, two of the extremities of which are soldered together in a few points only, whilst the other two are placed in communication with one of the extremities of the wire of an excellent ther- mo-electric multiplier. The slightest changes of temperature at the points of junction give origin to an electrical current, which, iu reacting 656 ANIMAL HEAT. on the magnetic needle, causes it to deviate by a certain number of degrees, which conse- quently become indices of the temperature of the point of the needle, and therefore of the medium in which it is placed. The multiplier ought to be so sensitive as to show a deviation of one degree of the magnetic needle for each one-tenth of a degree of temperature as mea- sured by the centigrade scale, an amount of temperature made sensible by the union of the two ends of the wire which forms its circuit with an iron wire soldered by its ends. So much for the general principle upon which and by which the inquiries of Messrs. Becquerel and Breschet were conducted. As to all the precautions necessary to render re- searches of the kind fruitful, as these are nume- rous, we beg to refer for an account of them to the memoir of the authors themselves. Difference of temperature according to the depth. — By the means contrived by Becquerel and Breschet the temperature of the calf of the leg at the depth of four centimetres from the surface was found to be 36°,75 (about 98° F.), and at one centimetre 34°,50 (about 94° F.), a difference of 2°,25 (4° F.). In the chest the temperature at the depth of the pectoralis major, compared with that of the superficial cellular tissue at the depth of one centimetre, showed a corresponding difference; the deeper parts were 2°,25 (about 4° F.) higher than the more superficial. In seven experiments made on the arm the mean difference of temperature between the deeper strata of the biceps and the superficial cellular tissue over the same muscle amounted to 1°,59 c. in favour of the deeper parts. The next point of inquiry was to know whether it was enough to penetrate to the depth of three or four centimetres into the trunk and limbs to attain the points of highest temperature in these parts. With this view we have compared the observations made by the authors mention- ed, in the same individual, with regard to the temperature of the mouth and of the biceps muscle, and we find that the mean temperature of the mouth was 36°,89, that of the biceps 36°,88, (about 98° F.), — a result which may be called identical with the former. The mean of seven other experiments, however, shows the relation of 36°,89 c. for the mouth, of 36°, 75 c. for the biceps ; the difference here is evidently in favour of the mouth. It were to be wished that inquiries in this direction were multiplied in order that absolute certainty may yet be attained. In the preceding experiments, in penetrating to different depths, the nature of the tissues at- tained also differs, a circumstance which must tend to complicate the results ; for it is possi- ble that the nature of the tissue may have some influence on the evolution of heat. This is even an inference which we should deduce from the principles already established, were it merely in consideration of the different quanti- ties of blood they contain. And this conclu- sion is even confirmed by the experiments of the parties mentioned ; for on compressing the humeral artery strongly, the motion of the nee- dle immediately announced a fall of tempera- ture to the extent of several tenths of a degree. This experiment is interesting from the rapidity and precision of the effect. There are other cases well known by which we are led to a corresponding conclusion ; but nowhere else is the fact seen in so simple a guise, or in so ma- nifest a relation of cause and effect. In opera- tions for aneurism, indeed, and other cases re- quiring the ligature of a large artery, the tem- perature of the parts supplied by the vessel tied falls so low as to require to be supported by artificial warmth ; but then a severe and bloody operation has been performed by which the conditions are complicated. In the expe- riment mentioned, on the contrary, nothing occurs to disturb the state of the economy ; the effect instantly follows the cause, and its amount is even at the same moment ascer- tained. Seeing, then, that in the same tissue the freer or more interrupted access of arterial blood causes the temperature to vary, it is fair to infer that the relative freedom of access or quantity of this fluid vvhicli circulates through other tissues should have an influence upon their temperature ; in other words, that tissues differ in their power of producing heat according to the quantity of blood which circulates through them. We can scarcely doubt, therefore, but that the differences of temperature observed be- tween the deeper and more superficial parts are complicated by the mere fact of difference of distance from the surface, and also by the cir- cumstance of difference of tissue. The super- ficial layer in the preceding experiments was cellular membrane ; the deeper layer was mus- cular. But the muscles receive a much larger quantity of blood than the cellular membrane, and their temperature, from this circumstance alone, ought to be higher.* * [Messrs. Becquerel and Breschet, in a memoir lately read before the Royal Academy of Sciences, (Ann. des Sciences Nat. Mai 1838,) entitled, " Further Observations on the Temperature of the Tissues of the body of Man and the lower Animals, as ascertained by means of thermo-electric effects," have made a few additional observations which de- serve quotation in this place. The temperature of the mouth being used as the standard of compari- son, the temperature of the biceps muscle was found to be but 36°, 20 c, instead of 3b'°, 60, which was the term derived from previous experi- ments, and to fall short of the temperature of the mouth by as many as 4° c. (above 7° F.) In making experiments upon the influence of the temperature of surrounding media upon that of the tissues, Messrs. Becquerel and Breschet intro- duced the needles of their thermo -electrical appara- tus into the biceps muscles of two young and healthy individuals, the air at the time marking 16° c. (61°F. ). The magnetic needle did not deviate in the least ; so that the two muscles possessed precisely the same temperature. One of the arms was now immersed for a quarter of an hour in water of the temperature successively of 10°, 8°, 6°, and 0°- c. (50°, 47°, 43°, and 32° F.). The deviation of the needle did not amount to more than two degrees of its scale in favour of the muscle of the arm which was not plunged into the water. The partial cold hath, consequently, had only caused a depression of temperature to the extent of about one-fifth of a degree c. The arm being now plunged into water ANIMAL HEAT. 657 We might even deduce from this a fact of great importance in the animal economy, viz. that muscular contraction is a cause of heat, in- asmuch as it determines the afflux of blood to- wards the muscles themselves as well as to- wards all the surrounding parts. It is very difficult to conceive an occasion of verifying this position in its simplicity ; for bodily efforts, in which the skin becomes red and injected, are always accompanied with some disturbance of the respiration and motion of the blood. We have, however, had an opportunity of seeing one individual of athletic powers, who, by merely throwing the muscles of the fore-arm into strong contraction, could cause the integu- ments of the forearm to become red. During the act of muscular contraction consequently, the temperatuie must have a tendency to rise. at the temperature of 42° c. (108° F.) for fifteen minutes, the temperature of the mu-cle as compared with that of the other was found to have increased one - fifth of a degree. When the whole body was plunged in a hot hath at the temperature of 49° c. (120p F. ), the deviation of the needle varied from 12° to 13° and 14° of its scale, which indicated a rise in tem- perature of from one-fifth to two-fifths of a degree c. The pulse was increased to 112 beats per minute, the body being immersed in this bath. The tempe- rature of the body before immersion was 36°, 70 c. (98° F.), a degree to which it immediately returned after coming out of the bath. In trying experi- ments of the same kind subsequently, but with baths at a somewhat lower temperature, namely, 42°, 50 (109° F.), no rise of temperature was indi- cated. The immersion in these cases was not con- tinued for more than twenty minutes. Had it been protracted for a longer time, the result might have been different. When a dog, whose muscles indi- cated a temperature of 33°, 50 (102° F.), was plunged into a hot bath at 49° c. (120° F.), the temperature rose rapidly by half a degree, a degree, and finally two degrees c. ; but the animal had be- come so much enraged that it was found necessary to take him out of the water. The needle of the apparatus being passed into the chest, a like rise in temperature was indicated ; but the rise in tempe- rature was found to happen principally when the animal became angry ; and it is doubtful how far the slate of exasperation influenced the results. In one experiment the one needle being passed into the biceps muscle of a young man, the other into the long radial supinator of a man aged forty- five, no sensible deviation of the magnetic indicator ensued. A vein was then opened in one of the arms, as near as possible to the point at which the needle had been introduced, but no change of tem- perature took place either during or after the flow of the blood. The common iliac artery of a dog was now isolated and a ligature thrown loosely round it, so that it could be compressed or left free at pleasure, and one of the needles of the apparatus plunged into the fleshy part of the thigh. The current of blood having been interrupted, the tem- perature of the limb began to fall, but not until after the lapse of an interval of twenty minutes, when it still amounted to no more than about half a degree c. The free access of blood having been restored, the temperature soon rose again to the normal point. The effect, though trifling in this case, — and the same experiment was repeated several times always with the same result, —is still suffi- cient to show that the arterial blood exerts a direct influence upon the temperature of the animal tis- sues. The effect, however, it is obvious from the time which elapses before it becomes apparent, is to be'attributed, not to the blood which is circulating in the trunks and branches of the vessels, but to that which is contained in the vascular rete.— Ed.] vol. ji. This fact is demonstrated in the most satis- factory manner by the delicate experiments of Messrs. Becquerel and Breschet as follows. When one of the joinings ( soudures ) is kept uniformly at a temperature of 36° c. (97° F.). and the other is inserted into the biceps muscle with the arm extended, the magnetic needle was found to deviate about .10 of a degree. On the arm being bent, however, the amount of deviation was observed to increase suddenly to the extent of from one to two degrees. Waiting till the oscillation of the needle and its return are completed, if the arm be bent anew so as to give a fresh impulse to the needle for several times in succession, a deviation of fifteen degrees is obtained at length, equivalent to a difference of five degrees in comparison with the original deviation, and corresponding to an increase of about half a degree of tem- perature as measured by the centigrade scale. If the needle be inserted into the biceps, and the arm be used in the action of sawing for about five minutes, the temperature is observed to rise considerably, sometimes to the amount of a degree centigrade. In these researches, then, we have evidence of facts of which we could not have acquired any precise information by our ordinary means of investigation. Every one, indeed, knows that exercise warms the body ; but every one also sees that in producing this effect, besides the contraction of the voluntary muscles, exercise is accompanied by an acceleration in the mo- tions of the heart and organs of respiration. In this simultaneous concurrence of a variety of phenomena, it was impossible to distin- guish the share which each had in the general result. Such an analysis could only be made by an experiment of the delicate and ingenious description of that which has been detailed. It would appear that it is by the repetition of the muscular contraction after each relaxa- tion that the highest evolution of heat is ob- tained, each contraction producing a slight in- crease of temperature, which, with the addition of that which follows, mounts to a certain limited point which it cannot pass. Let us remark, however, that the mere persistence of a primary contraction ought to have the effect of causing or maintaining a temperature higher than that which is evolved by a contraction followed immediately by relaxation ; indeed it is now known that a permanent muscular con- traction is but a series and succession of smaller and imperceptible contractions, following each other with extreme rapidity. It were well to observe here, that neighbour- ing parts must increase in temperature at the same time much less in consequence of the direct communication of heat in virtue of con- tiguity than by the afflux of blood, which, transmitted to the muscles in larger quantity, must also be more copiously than usual dis- tributed to adjacent tissues. The relaxation of the muscles ought, on the other hand, to have a tendency to reduce the temperature, and this by so much the more as the relaxation is more complete. From all this it follows that the attitude and state of the body will be favours- 2 x 658 ANIMAL HEAT. ble to cooling in the ratio of the general relax- ation of the muscles, and of the degree in which each of them in particular is in a state of qui- escence. This is what happens in sleep, of which we shall speak by-and-bye. In the rise of temperature observed along with muscular contraction, we have in the first place only considered the action of the blood ; but neither contraction of the muscles nor the afflux of a larger quantity of blood could take place without the nervous influence; for it is the will which determines the muscular contrac- tion, and the will only acts through the me- dium of the nerves which are distributed to the muscles. From this consideration it follows equally as from general relations pre- viously exposed, that whatever lessens the nervous influence will likewise tend to reduce the temperature. Here we are, then, reverting to the two general conditions which we had already found to be the most influential in ca- lorification, namely, the arterial blood and the nervous system. This examination of the relative tempera- tures of the different parts of the body has led us, by the immediate comparison of the super- ficial and deeper layers, to the consideration of the Influence of external temperature. — An in- ert or inanimate body of higher temperature than the surrounding medium will of neces- sity cool faster at its surface than in its internal parts. A living body, likewise, having within itself a permanent source of heat, which we shall suppose equally distributed through it, will lose more caloric from its surface than from its interior. This loss will become apparent by the cooling of the surface, so long as the source of heat remains everywhere equal. If, on the contrary, it be unequally distributed, if it be greater towards the surface, so as to compensate the greater loss which takes place there, the surface will have the same temperature as the interior. Without such a supposition it were necessary that the surface of the body should be lower in tem- perature than the interior. This, indeed, is the actual state of the case. The external parts of living bodies are colder than the internal parts, because on the one hand the focus of heat is less, by reason of the nature of the component tissues, and on the other because the loss of heat there is greater. When the external tem- perature falls, then the outer layers will tend to sink in temperature also, and will, in fact, sink so long as the internal source of heat remains the same. This partial refrigeration will be propagated internally, and the general tem- perature will be lessened unless the economy provides against such an occurrence by an in- crease of activity in its calorific powers. The same reasoning is applicable to move- ments of the temperature of bodies under the influence of that of the air. Heat will be propagated from without inwards, and will raise the general temperature of the body, un- less it lessens in the same proportion as it re- ceives external temperature, that which it pro- duces of itself. The consideration of the changes in the in- tensity of the internal focus, in other words, in the faculty of producing heat, and of the con- ditions which determine these, is the most im- portant point of all in the study of animal heat, on account of the multitude of practical applications which result from it. It is obvious from what has already been said that there is an essential difference between inert or inanimate and animate bodies subjected to the influence of external temperature. The temperature of the former depends solely on the general laws which regulate the propaga- tion of heat, whilst the temperature of the others is subjected to the influence of another element, namely, the heat which they them- selves produce. Did this element continue fixed and invariable, it would be possible to determine, by the application of the known data of physics, what must be the temperature of a living body under the influence of a given external temperature. But if this element varies, and the laws according to which it varies are unknown, it becomes impossible to predict in what manner the temperature of an animal will be affected by that of the medium in which it lives. It is only very lately, therefore, that the temperature of man and warm-blooded animals, with the exception of those that hy- bernate, has been believed to continue unaf- fected in the midst of extensive variations in the temperature of the surrounding atmosphere. Variations in the temperature of animal bodies in a state of health, independently of external temperature. — Duly to appreciate the inquiries that have been instituted in this direc- tion, the first question to be asked is, whether or not the temperature of the body presents variations, although external conditions continue the same, or nearly the same ? The answer here must be in the affirmative : the body varies in temperature at different times, exter- nal circumstances as to temperature continuing nearly the same. This is apparent in the ob- servations of Dr. John Davy instituted with another view, but quite available here. We perceive that the individual designated No. 1, having a temperature of 37° 8 (100° F.), when the air was at 26°, 4 (79° F.), had a tempera- ture of only 37°, 5 (99°, 75 F.) when the air was at 26°, 7 (80° F.), that is to say, the same person showed a third of a degree c. less of temperature, when the air, instead of becoming colder, had actually become warmer in the same proportion. The temperature of No. 3 was 37°, 2 (99° F.), when the air marked 25°, 5 (78° F.), and on another occasion it was only 36°, 9 (98° F.), when the air was 26° (79° F.) ; in other words, the temperature of the body, instead of rising, had actually fallen by 0°, 7 cent., when that of the external air had risen 0°, 9 cent. Influence of the natural temperature of the air on that of the body. — It must be obvious from the facts of the last paragraph that the influence of external temperature cannot be appreciated without having recourse to means of observation calculated to make variations dependent on foreign causes to disappear. ANIMAL HEAT. 659 To render the comparison of the mean sums obtained more certain, we shall confine our- selves to the observations of the inquirer just quoted, made upon the same individuals at different temperatures. The following series is after the data supplied by Dr. Davy : — Temperature of the air. Mean temperature of Jive men. 15°, 5 (60° F ) 36°, 85 (93° F.) 25°, 5 (78° F.) 37°, 16 (99° F.) 26°, 4 (79° F.) 37°, 32 (99° 5, F.) 26°, 7 (80° F.) 37°, 58 (100° F.) 27°, 8 (82° F.) 37°, 70 (100° 5, F.) It is apparent that these differences, even the extremes, do not surpass the limits of the variations which the same individual exhibits, or may experience spontaneously under the same temperature of the air. But when it is con- sidered that these differences are mean results, forming a series increasing with the rise of the external temperature, it is impossible to doubt of their standing in the relation to one another of cause and effect. If this dependence and connection actually exists, we must allow that it is very little obvious at the temperatures within the limits of which these observations were made ; for whilst the temperature of the air varied to the extent of 12°, 3 c , the changes in the mean temperature of the body did not exceed 0°, 9. Such slight differences being apt to leave uncertainty in the mind as to the cause producing them, we shall confirm the impres- sion they are nevertheless calculated to make by citing others, for which we are indebted to Dr. Reynaud, surgeon of the corvette La Chevrette, in a voyage of discovery in the Asiatic seas undertaken in the year 1827. The instruments used were furnished by the best makers of Paris, and were compared by M. Arago with those of the Observatory ; and the observations were made conjointly with M. Blosville, lieutenant of the vessel, charged by the Academy of Sciences of Paris with various researches in natural philosophy. Mean temperature of the' body deduced from ob- servations four times re- peated upon each of eight men, under the torrid zone, the external tempe- rature varying from 26° to 30° c. (79°, 86° F-X Mean temperature of the~\ same eight men observed | three times in the tern- I . perate zone, the external j temperature varying from 12° to 17° (53° to 62° F.)_ These results confirm those of Dr. Davy by so much the more as they were made within the same limits of external temperature. The mean rise of the temperature of the body un- der the influence of that of the air is also equally confirmed; but the amount is still less than as given by the English observer. It seems impossible, then, to doubt that the natural variations in the temperature of the air affect that of the body of man ; but this is only in a very trifling degree, at least within the >-37°, 58 (100 F.) 37°, 11 (99° F.) limits of temperature in which any extant ob- servations have been made. It is greatly to be regretted that neither of the observers quoted had opportunities of ascertaining the effects of much lower temperatures than those they have given. There are, it is true, many isolated ob- servations made by voyagers in the Arctic regions, both upon animals and man, and although conducted in no regular series, or as points of comparison with one another, they still lead to the same general result, namely, that great differences in the tempera- ture of the air cause slight differences in the temperature of the body of animals. Thus, in the voyage of Captain Parry it was observed that the temperature of the Mammalia was very high. With the external thermometer at — 29°, 4 (— 21°, F.), the temperature of the white hare was + 38°, 3 (101° F.). With the thermometer at — 32°, 8 (27° F.), the tempe- rature of a wolf was -+- 40°, 5 (105 F.); the temperature of the Arctic fox, under nearly the same circumstances, namely, when the thermo- meter was standing at — 35° ( — 31° F.), was as high as + 41° 5 (107° F.). Similar obser- vations have since been made in the same high latitudes upon man. The variations in the temperature of warm- blooded animals according to that of the seasons has been studied by the present writer, who con- firms the results just stated. The experiments of the writer were made upon a great num- ber of sparrows recently taken at different seasons of the year, which is preferable to keeping these creatures in captivity for any length of time. The mean temperature of these birds rose progressively from the depth of winter to the height of summer, within the limits of from two to three degrees centigrade. The observations made on sparrows exhibited the greatest differences. In the month of Feb- ruary the mean temperature of these birds was found to be 40°, 8 (105° F.) ; in April 42° (108° F.), in July 43°, 77 (111° F.). The temperature from this time began to decline, and followed, in the same ratio in which it had increased, the sinking temperature of the year. Influence of media upon temperature. — The media in which animals live do not act solely in the ratio of their temperature, but also by virtue of the intensity of their cooling or heating power. Thus air and water at the same degree of heat will have a very different influ- ence on the temperature of the bodies plunged in them. The power of air in heating or cooling is commonly known to be very inferior to that of water. Bodies acquire or lose tem- perature much more slowly in air than in water. A water-bath according to its temperature com- municates sensations of heat or cold far more rapidly and powerfully than an air-bath. The writer and M. Centil made the following experiment :— A young man seventeen years of age, of strong constitution and in good health, after remaining for twenty minutes in a bath the water of which marked 13° R. (61°, 5 F.), whilst the air was 14°, R. (63° F.), half an hour afterwards was found to have lost haM' a degree of his original heat in the mouth and 2x2 660 ANIMAL HEAT. hands, and a degree and a half in the feet. This temperature of the air may be regarded as a mean, or intermediate between heat and cold, and may be termed temperate (61° to 62° F.). It was superior to that of the water by a degree R., and yet the water of the bath, after immersion in it for no longer a time than twenty minutes, had reduced the temperature of the body according to its parts from half a degree to a degree and a half R. Effects of external temperature upon an isolated part of the body. — Under this head let us examine, 1st, the extent of the effect, and 2nd, its influence on other parts. The facts we shall borrow from the researches just quoted, those namely of myself and M. Centil. The hand, at 29° R. (98° F.) having been kept immersed in a tub of water cooled down to + 4° R. (41°F.), in all during twenty minutes, five minutes after it had been taken put of the water, marked no higher a tempera- ture than 10° R. (55° F.) This experiment shows how rapid and extensive, and how much beyond what could have been anticipated, may be the refrigerating effects of cold water applied to an extremity. Another not less remarkable result is the singular slowness with which the temperature of an extremity is regained, although exposed to the gentle warmth of the air. The hand in the above experiment, after the lapse of twenty-five minutes from the time it was removed from the water, was still no higher than 16i° R. (69° F.), and after the expiration of an hour and a half it was only 24£° R. (87° F.). The foot, in the same cir- cumstance-, gave nearly analogous results. In a number of experiments of the same nature as the last, where one hand was plunged in water cooled down by ice, the other hand, which was not subjected to the action of the cold bath, lost nearly 5° R. in temperature. It is therefore apparent, 1st, that partial chills, or the exposure of individual parts to low temperatures, may be and are felt very extensively even when the cold is not very severe ; 2nd, that the chilling of a single part, such as the hand or the foot, may cause a loss of temperature in all the other parts of the body, even far beyond what could have been pre- sumed as likely or possible. These facts give a key to the right understanding of the immense influence which partial chills are capable of exercising on the state of the general health Of the effects of partial heating. — The hand being immersed in water heated to the tem- perature of 34° R. (109° F.),rose one degree of the same scale, and the temperature of other remote parts not immediately exposed to the influence of heat were found to have risen in a corresponding degree. Whence follows this axiom, — that we cannot either raise or lower the temperature of any one part of the bodu without all the other parts of the frame being affected, and suffering a corresponding rise or Jail in temperature, more or less according to circumstances. We may further presume from the comparison of these facts, that the body and its parts are liable to variations of temperature towards either extremity of the scale from the mean, much more considerable than are generally imagined. This latter fact will appear very evidently from the other inquiries which are now to engage our atten- tion. Effects of an excessively high or excessively low external temperature upon the temperature of the body. — Hitherto we have only considered the changes in the temperature of the body pro- duced by moderate degrees of external heat and cold. We now pass on to the examination of the effects caused by extreme external tempera- tures, and first of those that follow from excessive heat; designating by excessive heat any temperature that surpasses that of the human body. On a summer's day, the temperature of the air being 37°, 77 c. (100° F.), Franklin observed that the tempera- ture of his own body was nearly 35°, 55 c. (96° F.). This fact, which is perhaps the first of the kind noted, is highly deserving of atten- tion. It proves that man, and by analogy otheranimals,havea power of keeping their tem- perature inferior to that of the air. As in the ob- servation quoted there is no means of knowing what effect the excessive external temperature had produced upon the temperature of the observer, recourse must be had to other facts. In numerous experiments made in England by Dr. Fordyce and his friends, and subsequently by Dr. Dobson, in which these experimenters exposed themselves to very high temperatures, which on some occasions exceeded that of boiling water, the heat of the body was never observed to rise more than one, two, three, or four degrees of Fahrenheit's scale at the utmost. As in these experiments the object especially proposed was to determine the degree of external temperature which the body could bear, all the attention which would have been desirable was not given to determine the tem- perature of the body before, during, and after the experiments. This is an omission which is common to the experiments of For- dyce and Dobson. The highest temperature of the body noted by Dr. Dobson is 102° F., but he does not mention the heat before the experi- ment, nor does he notice the rate of cooling subsequent to its termination. The highest temperatures of the human body exposed to excessive heats ever observed, were remarked by Messrs. Delaroche and Berger in their own persons. The temperature of M. Delaroche being 56° 56 c. (98° F.) increased 5° of the centigrade scale, by remaining exposed in a chamber the temperature of which was 80° c. (176° F.). M. Berger, whose temperature was the same as that of M. Delaroche, gained 4°c. by remaining for sixteen minutes in the hot chamber at 87° c. (188°, 5 F.). These experiments are liable to this objection, — that the temperature was taken in the mouth in an atmosphere of much higher temperature, which might have some influence in raising the ther- mometer. To arrive at conclusions against which no kind of objection could be raised, Messrs. Delaroche and Berger exposed them- selves in succession in a box, out of which they could pass their head ; the hot air or vapour of ANIMAL HEAT. 661 the interior being prevented from escaping by means of a circular pad of soft napkins placed between the edge of the outlet and the neck. The temperature of the mouth, in this way, if it was increased, must be increased in consequence of a rise of temperature in the parts of the body included in the bath. After a stay of seventeen minutes in the bath, heated from 37°, 5 to 48°, 75 c. (99° to 120° F.), the temperature of M. Delaroche's mouth rose 3°, 12 c. Under similar circumstances, the temperature of the bath being from 40° to 41°, 25 c. (104° to 106° F.), the temperature of M. Berger's mouth increased 1°, 7 c. in the course of fifteen minutes. It is pretty obvious that experiments upon the human subject cannot be pushed far enough to ascertain the highest amount of temperature that can be acquired under the influence of exposure to air of excessively high tempera- ture. To judge of this analogically, recourse must be had to warm-blooded animals of the two classes, Mammalia and Birds. Messrs. Delaroche and Berger consequently exposed different species of Mammalia and Birds to dry hot air of different temperatures, from 50° to 03°, 75 c. (122° to 201° P.), leaving them im- mersed till they died. The whole of the ani- mals that were made subjects of experiment, in spite of diversity of class and species, and of the varieties of temperature to which they were exposed, had gained an increase of tem- perature nearly equal at the moment of their death. The limits of the variations being be- tween the terms 6°, 25 and 7°, 18 c, the amount of difference did not exceed 0°, 93 c. which is a very triflingquantity. It may therefore be inferred that man and the warm-blooded animals cannot, under the influence of exposure to dry air of excessively high temperature, have the heat of their body raised during life to a greater extent than from 7° to 8° c. The temperature of the body being increased to this extent becomes fatal. It is in fact only attained at the moment of dissolution ; perhaps death has virtually taken place before it is attained. We have seen that Franklin observed the temperature of his body to be lower than that of the air on a very hot day. Such a circum- stance is rare in what may be called natural con- ditions as regards man and the warm-blooded animals ; inasmuch as" it rarely happens that the temperature of the air surpasses that of their bodies generally. The case is different, however, as regards the cold-blooded tribes. It is not at all necessary that the temperature of the air be very high to afford opportunities of observing the phenomenon in question among cold-blooded animals. This was ob- served for the first time by Sir Charles Blagden in a frog, which on a summer's day, when the heat was by no means excessive, he observed to be lower in temperature than the surrounding air. A fact of this kind could not remain isolated and unconnected with others. Accord- ingly we observe among the experiments of Dr. Davy such facts as the following: — The temperature of the atmosphere being 32° c. (90° F.), that of a tortoise was only 29°, 4 (85° F.). The air marking 26°, 7 (80° F.), a frog indicated 25° (77° F.). The air being at 28°, 3 (83° F.), the blatta orientalis was at 23°, 9 (75° F.). The air at 26°, 19 c, (79°, 5 F.), a scorpion was at 25°, 3 (78° F.). It is therefore apparent that the phenomenon is general among animals with cold blood ; that during the highest heats of summer, the tem- perature still falling short of excessive, the heat of their bodies is below that of the air. There is thus a limit of summer temperature which separates two orders of phenomena relative to the temperature of cold-blooded animals. Starting from a mean temperature of the air, that of cold-blooded animals, the vertebrate as well as the invertebrate tribes, is superior to this mean, only varying in this respect within the narrow limits of from a few fractional parts of a degree to about four degrees centigrade, until the air attains the summer heat. Towards this limit the differences decrease, and the term 25° or 26° c. (77° to 79° F.) attained, they become nil. The inverse phenomenon is also observed : the temperature of the greater num- ber is inferior to that of the air, and the dif- ferences go on increasing with the rise in temperature of the external air. These phenomena are of great interest in themselves, but of still greater from the light they cast on questions of a similar kind relative to man and the warm-blooded tribes of crea- tion. The slight evolution of heat by the cold- blooded animals rendering their condition more simple, allows us to appreciate distinctly the influence of external causes. We now proceed to tieatof a third condition influencing temperature, namely, Evaporation. — The fluids so far surpass the solids in the bodies of animals that they cer- tainly constitute the larger portion of their masses ; and, further, the exterior surface of animal bodies generally is extremely porous. Animals are consequently subjected to the ordinary physical laws of evaporation. It is very long since, in addition to the sweat Di- visible perspiration, the existence of an invisible perspiration has been recognized. The latter is owing in great part to the effects of evaporation. Now evaporation cannot take place without the occurrence of cooling or loss of temperature in the ratio of the quantity of vapour formed. Without keeping this cause of refrigeration in view, we should fall into serious mistakes in estimating the heat of animals. If, for ex- ample, we would compare the heat of two animals, which, unwittingly to the observer, should be under different conditions of eva- poration, we should deceive ourselves greatly in regard to their respective temperatures. It is even so with reference to another fact bearing upon temperature, which is often forced on the attention, and which has almost always led inquirers into error. There are many ani- mals among the inferior classes of the Inverte- brata, which tried by the thermometer exhibit no difference in temperature from that of the surrounding air. These creatures do not con- sequently, appear to have any faculty of pro- ducing heat. But in the mere fact of their main- 662 ANIMAL HEAT. taming the temperature of the air about them, an inherent capacity to produce heat is apparent. Did they evolve no caloric, they would fall below the temperature of the air, in conse- quence of the evaporation which goes on from the surface of their bodies. They must of necessity produce as much as is necessary to repair the loss which takes place from this cause. What we have said of animals is equally applicable to vegetables. To explain the pro- gression of the temperature of cold-blooded animals, which we have exposed above, regard must be had to the relation which connects the quantity of vapour formed with the degree of external temperature. Within moderate limits, which may be styled temperate, the vapour formed will be nearly as the degrees of tem- perature of the air. But under higher tempera- tures, evaporation will go on in a greater ratio than that of the external temperature. Thus when the air is cool or moderately warm, eva- poration is trifling, and among the superior classes of cold-blooded animals heat enough is produced to maintain their temperature above that of the air. But when the air becomes warmer, as in the height of summer, evapora- tion and the cold which results from it increase in a far greater ratio than the temperature of the body, so that the body remains at a tem- perature inferior to that of the air, and this by so much the more as the external tempera- ture rises higher. Twenty-five degrees is the limit at which this change commences in regard to cold-blooded animals. But it is obvious that a higher degree must be necessary to ob- serve such phenomena in man and the warm- blooded tribes, inasmuch as the heat from without is for a long time added to that pro- duced internally, and which among the warm- blooded tribes is so much greater in amount than it is among the cold-blooded. Relations of the bulk of the body with animal heal. — If the temperature of the larger animals be compared with that of the smaller, it will be found that the former do not mark so high a degree as the latter. In the elephant and horse, for instance, no higher a temperature than 37°, 5 c. (100° F.) has been observed, whilst in the rat and squirrel temperatures of 38°, 8, and of 39°, 4 (102° and 103° F.) have been noted. To prove that the difference is less owing to the order or species than to the simple size, we shall contrast several animals belonging to the same order, selecting the ruminants. The temperature of the air being the same, namely, 26° c. (79° F.), the tem- perature of the ox was found to be 38°, 9 (102° F.), whilst that of a castrated he-goat was 39° 5 (103° F.), and that of the she-goat and sheep 40° (104° F.) * It is evident that smallness of size must in itself be one of the conditions unfavourable to height of temperature among animals, when this is merely viewed in relation with the am- bient medium. As the external temperature is almost always lower than that of the bodies of * Vide Observ. of Dr. Davy. animals, the ambient medium tends to lower their temperature ; and small bodies having a more extensive surface in reference to their mass than large bodies, small animals must have a greater tendency to lose heat than larger animals. But, on the other hand, the circulation and respiratory motions generally increase in rapidity in proportion to the smallness of size ; and we have seen that acceleration of these motions had an influence in keeping up the temperature. With a small size of the body, consequently, we find associated a higher activity of function which tends to compensate the disadvantage resulting from inferior size in reference to tem- perature. In fact it constantly happens that this higher activity more than compensates the cooling disposition from inferiority of size, and causes the balance to incline towards the side of higher temperature. It must be apparent, however, that there is no occasion for such a preponderance always existing in the case of small animals. And then we know that the motions of circulation and of respiration cannot be greatly accelerated without causing incon- venience and even danger to health and life. It follows that the external temperature being liable to fall disproportionately low, small ani- mals have not, under like disadvantageous cir- cumstances, the same power as larger animals of supporting their temperature. The relations of size naturally lead us to consider those that depend on age. Relations of age with animal heat. — The size of the body changes with the age. The same relations between bulk of body and de- velopment of heat ought therefore to be ex- hibited in youth as compared with adult age. In early life the greater rapidity of the motions of circulation and respiration, all things else being equal, ought to increase the heat. At the same time the constitution differs in other respects, and if these were unfavourable to the evolution of heat, it would be impossible to foresee the result of these two opposite ten- dencies. Nevertheless it is probable, from what we have seen to happen in warm-blooded animals of different sizes, that there might occur a period in early life when the heat would be higher than in adult age. A confirmation of this inference may be found in comparing the different observations of Dr. Davy, who has given a table of the temperatures of fifteen chil- dren from four to fourteen years, the mean age of the whole being nine years and nine months. The mean temperature of the bodies of these children was 38°, 31 (101° F.). But the mean temperature of twenty-one adults was no higher than 37°,82 (100° F.): a difference that seems the more worthy of being confided in from the temperature of the air having, at the time of the observations, been more favourable for the adults than for the children, this having, in re- ference to the former, been 26° and 26°, 7 (79° and 80° F.), whilst when the latter were made the subjects of investigation, it was but 24° and 26° (75°, 5 and 79° F.). It seems impossible, therefore, to doubt from what precedes, that size is not an element which has much influence in the particular ANIMAL HEAT. 663 direction we are considering. We have seen that with a decrease in the size of adult Mam- malia the circulatory and respiratory motions were progressively accelerated, and that by this means the disadvantages as regards cooling in consequence of a smaller relative size of the body, are in some measure compensated, some- times, indeed, we have seen the balance in- clined the other way, and the greater rapidity of the motions more than compensate for the diminished size of the body. Great rapidity of the respiratory and circulatory motions may co-exist with other organic conditions having an opposite tendency as regards temperature ; and, according to the relations of these, and as the one or the other predominates, we may have two different states of temperature in early life. This proposition is even made ap- parent when we compare the constitution in early youth and in adult age. In early life the celerity of the motions has led to the belief that all the functions of nutrition were pecu- liarly active. But strength or energy is not always an accompaniment of simple celerity ; on the contrary rapidity is generally indicative of absence of power. It is quite true that in early life not only are circulation and respira- tion, but digestion, assimilation, and growth likewise, much more rapid than in the adult state. But does it follow from this thut the materials of the blood are elaborated in the same degree of perfection, or that the products of the action and contact of this fluid, the vaiious tissues, &c. of the body, are all as com- pletely formed ? Everything conduces to make us believe that the reverse is the case. If on the one hand rapidity of movement be a cha- racter of early life, weakness is a feature still more manifest. If the nervous system there- fore, although acting rapidly, is less energetic, in the same proportion there may be an age at which the influence of this weakness on the production of heat may be manifest. And, as the weakness is greater as the being is younger, it is in the very earliest periods of independent existence that this relation must be inves- tigated. Now such a relationship does aclually exist, although an opinion to the contrary had always been entertained until direct experi- ments settled the question definitively. These experiments were performed by the writer, and a summary of them is here given. If the temperature of new-born puppies lying beside their mother be taken, it will be found from one to three degrees inferior to that of the parent. The same thing obtains in regard to the young of the rat, the rabbit, the guinea-pig, &c. and is probably universal among the Mam- malia. Among Birds the same circumstance presents itself in a still more marked degree. If they be taken out of the nest in the first week or even fortnight of their existence, the difference of temperature extends to from 2° to 5° c. between the young and the parents. The fact has been ascertained in regard to the sparrow, the swallow, the martin, the sparrow- hawk, the magpie, the thrush, the starling, fcc. &c, and is probably, as among Mammalia, universal. Whence we may conclude that the phenomenon is general as regards warm-blooded animals. We might have taken it for granted that man was comprised within the category, but it is just as well to have the assurance that he forms no exception to the law, that he has no peculiar privilege in this respect. To have a precise term of comparison, the temperature of twenty adults was taken at the same time, the thermometer being applied in the axilla. The temperature of these twenty persons varied between 35°, 5 and 37° c. (96° and 99° F.) ; the mean term was therefore 36°, 12 (97° F.). The temperature of ten infants varying from a few hours to two days in age, ascertained in the same manner, varied between 34° and 35° 5 c. (93°, 5 and 96° F.). The mean was there- fore 34°, 75 c. (about 94°, 5 F.). There was consequently a difference of nearly two degrees between the temperature of the adult and of the newly born babes. Man is therefore proved to be subjected to the same law here as ani- mals having warm blood in general, the young of which, so far as they have been examined, and we may presume universally, are inferior in temperature to their parents. There are, therefore, two periods in youth at which the bodily temperature differs from that of the adult age. These may be distinguished as the first and second periods of infancy or youth. The first extends from birth to an in- definite period, but which is nearer or more remote from the period of birth in different cases. The second is included between the fourth and the fourteenth year ; the limits can- not be more accurately determined. In the first the temperature is lower than in adult age, in the second it is higher The differences of temperature in the first age of infancy, and the adult age, although very sensible and impor- tant as regards the economy, are indices of a difference incomparably greater than their numerical indication might be taken to imply. In fact, if the manner of observing be altered, results of so extraordinary a character are come to as to surpass all expectation. To deve- lope these the temperature of the newly born being must not be taken only when it is in contact with its mother. If, after having as- certained the temperature of a puppy in this position, it be removed from the mother and kept isolated, the temperature will be found to fall rapidly; and this phenomenon takes place not only when the air is cold, but when it is mild. The phenomenon does not commence after a term ; it is apparent from the moment the separation takes place, and is very sensi- ble after the lapse of a few minutes. The fol- lowing is the rate of cooling of a puppy twenty- four hours old, the external temperature being 13° c. (about 55°, 5 F.), taken at intervals of ten minutes; the series of course represents the successive losses of temperature in the course of the small intervals of time indicated : — temperature in commencing the observations 36°, 87 c; the declensions in temperature at intervals of ten minutes successively, 0°, 63 1°, 12, 1°,38, 1°,25, 1°,29, 0°, 87, 1°,63, 0°, 25, 1°, 0; in thirty-five minutes the tem- perature declined farther 1°, 25; in thirty-five 664 ANIMAL HE AT. minutes more it fell 3°, 12; in thirty minutes more 2°, 50; in twenty-five minutes more 1°, 25; in thirty minutes morel0, 25; so that in the course of four hours in all the tempe- rature declined by the amount of 18°, 12' of the centigrade scale (about 33° F.)! Not only had the temperature of the animal sunk by so large a quantity in so short a period of time, the external temperature being pleasant, but it actually could maintain its temperature at no higher a grade than 6°, 75 c. (44°, 5, F.) above that of the atmosphere. Experiments of the same kind performed on three other puppies of the same litter presented results in all respects analogous. The cooling may even go much further by protracting the period during which the young animals are kept apart from their parent. For instance, four puppies, twenty- four hours old and of much smaller size than the subjects of the former experiments, after having sunk 16° c. in four hours and thirty minutes, lost six degrees more of temperature in the succeeding eight hours and thirty mi- nutes, the air remaining all the while at 13° c. (55°, 5 F.). They consequently lost twenty- two degrees centigrade in thirteen hours; and, what is very remarkable, their final temperature was but one degree above that of the surround- ing air. Kittens and rabbits of the same age exhibited similar phenomena, if possible in a more striking degree. Some kittens were ob- served to cool twenty degrees centigrade within the short interval of three hours and a half, and some young rabbits suffered the same de- pression of temperature in two hours and ten minutes, the air being at the time at 14° c. (57°, 5 F.). These phenomena are unques- tionably among the most remarkable we wit- ness in warm-blooded animals. For here we have species of different genera of the Carni- vora and Rodentia, which at two periods of their existence present the extremes in the pro- duction of heat. They may be said to be, to all intents and purposes, cold-blooded ani- mals, with reference to temperature, during the earliest period of life; they are only truly warm blooded animals in a later stage of their existence. The same phenomena undoubtedly present themselves in many other species ; but it would not be reasonable to suppose that they were exhibited by all. The phenomena being connected with the state of constitution, it may be expected to vary in diffeient genera and families; and this, in fact, is what actually happens. A young guinea-pia, for instance, having a temperature of 38° c. (101°, 5 F.), will maintain this tem- perature when the atmosphere is mild, although separated from its mother. It is the same with the goat. These instances are enough to give us a key to the external characters in relation with the different capacities to produce heat inherent in the young Mammalia. In the first place we observe a manifest relation with the state of energy of the nervous system : on the one hand we have the puppy, the kitten, the rabbit, which are born extremely weak ; on the other we have those animals that come into the world in a condition to walk, to eat, and, as it were, furnished forth to a certain extent with the means of providing for their wants. The question, however, is to discover some zoolo- gical character in relation with these differ- ences. If this were to be derived from the state of the organs of locomotion, of the faculty of walking, we should sometimes be led into error ; for man, at the period of his birth and long afterwards, is not in a condition to hold himself erect, and yet his temperature is main- tained to within one or two degrees of that of his mother, if the external temperature be but mild. There is, however, one character that appears general ; this is the state of. the eyes. Those species of Mammalia which in the earlier period of their existence do not maintain their temperature, that of the external atmosphere being mild or warm, but cool down to the stundard of the cold-blooded animals, are born with their eyes closed ; whilst those which main- tain their temperature, that of the external atmosphere being mild, are born with their ei/es open ; and this, whether they can walk about like the guinea-pig, the kid, &c, or cannot do so, as is the case with the human infant in par- ticular. This general view of the state of energy of the nervous system in relation with the production of heat in early life, comes in aid, in a very remarkable manner, of the general principles which have been already deduced in regard to the calorific power. In going more deeply into the subject, the confirmation becomes more manifest and more complete. The state of the eyes affords a mere external and zoological in- dication. It is but an indication of other deep modifications of the economy, which it is essential to determine more closely. Now in examining the state of the organs generally of puppies at the period of their birth, we observe a remarkable disposition of the sanguiferous system. The ductus arteriosus continues per- vious and of large size. The consequence of this structure is that a free communication is established between the arterial and venous blood, by which they are mingled in large pro- portion one with another. And here we have precisely the physiological character derived from the nature or quality of the blood which distinguishes the cold-blooded from the warm- blooded Vertebiata (in the adult age under- stood). This character is exactly the same in the other species of Mammalia which we have mentioned as losing temperature and attaining the standard of the cold-blooded tribes. On the other hand, in the guinea-pig, to take an individual instance, which from the first day of its extra-uterine existence maintains its tempera- ture nearly on a level with that of its parent when the air is temperate, the ductus arteriosus is closed immediately after birth. The arterial remaining distinct from the venous blood, this creature is therefore born with the organization characteristic of warm-blooded animals, and presents phenomena having reference to calori- fication of the same kind as adult warm-blooded animals. This relation is preserved in the young Mammalia in every modification in a pecu- ANIMAL HEAT. 665 liarly interesting manner. The young Mam- malia which are born with the eyes closed, at first present the phenomena of refrigeration nearly in the same degree during the two or three first days of their life ; though they after- wards exhibit differences of great extent in this respect. Thus a young rabbit two days old had cooled down to 14° from 23° c. (to 58° from 74° F.) in the course of three hours fifty minutes, theair being at the time temperate ; another three days old took seven hours twenty-five minutes to cool through a range of 18° c, when the process of refrigeration ceased. A third, of the age of five days only, lost 5° c. in temperature in the course of one hour fifty-five minutes, and maintained itself afterwards at this tem- perature. During the following days, smaller and smaller depressions of temperature were observed, till the eleventh day after birth, when the power of sustaining the temperature a little below that of the adult female parent seemed to be acquired permanently. When the modifi- cations of internal structure are examined during this interval of time, we find that the ductus arteriosus has been contracting in the same proportion as the faculty of maintaining the temperature has been increasing, and that it is entirely closed at the epoch when the tem- perature becomes stationary, the external tem- perature being understood all the while as mild or pleasant. At the same period pre- cisely too, the eyes are unsealed, a circum- stance which confirms the exactness of the character derived from the state of this latter organ, as distinctive of the young of those Mammalia which are born as it were cold- blooded animals, from those that come into the world with the distinguishing attribute of warm- blooded animals. Among the young of Birds we observe as marked differences in the calorific function as we have just acknowledged among Mammalia. Some lose heat rapidly when separated from the mother; others maintain their temperature to within a little of that of their species. Spar- rows, for instance, which have been hatched but a short while, present a temperature from 4° to 5° c. lower than that of their parents when still contained in the nest, where they contribute to each other's warmth. But taken out of the nest and isolated, although the temperature be that of summer they begin to cool with extreme rapidity. A young sparrow a few days old lost as many as 12° c. in the short space of one hour seven minutes, the air at the time marking 22° c. (72° F.). The same thing happens with swallows, sparrow-hawks, &c. But the law is not universal; it does not hold in re- ference to all the genera. There are several that have the power of sustaining their tempera- ture in spring and summer at a degree but little below that of their parents. Birds, there- fore, form two groups as regards the production of temperature, just as the Mammalia do. The first cool down to the standard of cold-blooded animals; the second preserve their warmth, when the air is mild or agreeable as it is in the spring and summer. But the zoological characters that distinguish them are not the same as among mammiferous animals. All birds are hatched or born with their eyes open. But there are other characters which coincide with the difference of temperature; and this consists in the absence or presence of feathers. The covering of those that are hatched so pro- vided, consists in a kind of down, very close and very warm, so that we might imagine the differences observed in the liability to lose heat or in the capacity to engender it, belonged to the coat. This has undoubtedly some influence, but analogy even will not suffer us to ascribe the chief effect to this cause. In the Mammalia which are born with their eyes closed, the refrigeration takes place to the same extent whether they are born with a fur-coat, as the kitten, the puppy, &c, or come into the world naked like the rabbit; the cooling is only more rapid in the latter than in the former. What further proves, and directly proves, that the refrigeration is not entirely due to the dif- ference in the external condition as regards covering, although this of course must go for something, is that when the want of natural covering is artificially supplied, the cooling does not go on the less certainly on this account, and to the same ultimate extent ; it only takes place somewhat more slowly. The counter- proof is attended with the same result. An adult sparrow which has had all its feathers clipped off does not at first suffer loss of tem- perature to the extent of more than a degree, and by-and-by recovers even this ; whilst a young bird of the same species, though fur- nished with some feathers, cools rapidly and to a great extent, as we have already seen. Birds are therefore divided into two groups as regards the production of heat. The one comprises those that are hatched with the skin naked, and which cool in a temperate air in the same manner as cold-blooded animals ; the other embraces those that are produced with a downy covering, and maintain their temperature at a considerable elevation in the ordinary heat of spring and sumtner. There is not a less remarkable contrast between these two groups of birds in point of calorific power, than between the two groups of Mammalia already mentioned ; but the zoological or external characters which dis- tinguish them in the present instance are not of the same kind. The state of the eyes does not apply here, for all Birds are disclosed with their eyes unsealed. They also all come into the world with the ductus arteriosus closed or nearly so, — a circumstance which might have been predicated, or inferred from analogy. Yet the young of Birds in the power of producing heat present diversities no less remarkable than are observed among the young of the Mammalia. The separation of the two kinds of blood con- sequently is not the only condition which influences the production of heat; but all that modifies the blood on the one hand, and the nervous system on the other, as we have had occasion to observe in a previous part of this paper. Now it happens that we have an op- portunity of applying this principle in a very particular manner in the instance of the two 666 ANIMAL HEAT. groups of Birds that engage us, and that differ so essentially in their powers of engender- ing caloric. In the one and in the other we observe the same difference in the state of the general strength which we have observed in the corresponding groups of the Mammalia. In the one which cools rapidly, there is the same state of weakness, of general impotency ; in the other the young are in a condition to walk, and in a certain sense to shift for themselves as soon as they have escaped from the shell'. We perceive then in the first place, that the nervous system is much less energetic in the former than in the latter group ; and in the second place, that the digestive powers are in an equal degree inferior in strength ; for they are not only unable to take food of themselves from muscular incapacity, but also from the lack of the requisite instinct, and, farther, from their digestive organs not being in a condition to elaborate food to any extent. It is on this last account that the parents supply their young with food which has suffered maceration in their own crops, or has even in their stomachs undergone a kind of incipient or partial solu- tion ; or otherwise the parents have the instinct to select such articles as are easiest of digestion, and best fitted for the weakly state of the digestive organs of their progeny. We have already observed that a delect in the powers of digestion implies a corresponding imperfection in the blood. Whence we must conclude by analogy that the blood in the birds of the first group is inferior in quality to that of the birds of the second group. We consequently still find the two general conditions which regulate the production of heat throughout the animal kingdom — the state of the blood, the slate of the nervous system. The same principles are applicable to the first period in the existence of all animals, without distinction of groups, as compared with adults. On the one hand we have ascertained that all without exception have a temperature lower than that of their parents ; on the other, nothing can be more manifest than their inferi- ority with reference to the energy of the nervous system. And more attentive and extensive ex- amination shows that this extends in like man- ner to the digestive functions, and consequently to those of nutrition generally. Let us first turn our eyes to the Mammalia. All of these are evidently inferior in this respect to the adult. This is proclaimed in the distin- guishing character of the class : the females are provided with glands for the purpose of prepa- ring a food appropriate to the state of weakness of their young. The state of the mouth of the young is a sufficient index of the defective power of the digestive organs ; the jaws are either wholly or partially without teefh. The softness, delicacy, paleness of colour, and insi- pidity of the tissues of young Mammalia, com- plete the evidence of the imperfect elaboration of the nutrient juices. If, therefore, the first and last products of the nutritive functions are in an inferior condition, can we suppose that the intermediate product, the blood, will not participate in this inferiority? We have already shown in what this consists among the Birds of the first group. With regard to the second, the general considerations relative to the difference of the tissues is equally applicable to them, and these considerations possess a high value. When very young warm-blooded animals, with- out any exception, are compared in this respect to the cold-blooded Vertebrata, we perceive a great analogy in their component tissues, which are softer and less savoury than among the adults of warm-blooded animals. It is thus that we can account for a striking anomaly in the nervous system of young warm-blooded animals, especially Mammalia. Their nervous system, particularly the encephalon, bears a higher proportionate ratio to the whole body than it does in the adult; but the softness and the other characters of the tissue of this organ in early life cause it to approximate in a re- markable manner in appearance and character to the same tissue in the cold-blooded Verte- brata: If, therefore, the relative volume predo- minate in early life, one of the conditions favourable to calorification, the inferiority in respect of tissue counterbalances this advan- tage, and is only compatible with very inferior manifestations of energy. It is obvious then that there is a universally pervading analogy between warm-blooded ani- mals in the first stages of their existence and adult cold-blooded Vertebrata, and that the pa- rallel holds good, not merely with reference to their inferior power of producing heat, but also with regard to the functions of nutrition gene- rally and the functions of the nervous system. There is one point upon which it is highly ne- cessary to insist, inasmuch as it is of the greatest importance, both theoretically and practically ; it is this : that the analogy in the direction in- dicated is by so much the more remarkable as the warm-blooded animal is born with charac- ters which distinguish it more strikingly from those it possesses when arrived at maturity. If it is born with the eyes closed, or without fur or feathers, instead of with the eyes open and the body covered with a fur coat or a thick down, it is because the creature comes into the world less perfectly developed in every respect, and the whole economy is more closely allied to that of inferior orders. This, in other words, is as much as to say that the creature is born at a period relatively precocious, or in a more imperfect condition. Whence it may be in- ferred that those warm-blooded animals which are born at a period short of the ordinary term of utero-gestation among the more perfect spe- cies, will present a more marked analogy with the cold-blooded tribes. Man himself will form no exception to this rule, which must be quite general. The verification of this law has been completed by the physiological experiments of the writer. A child born at the seventh month, perfectly healthy, and which had come into the world with so little difficulty that the accoucheur could not be fetched in time to re- ceive it, had been well clothed near a good fire when the temperature was taken at the axilla. This was found no higher than 32° c. (under 90° F.). Now we have seen that the mean of ANIMAL HEAT. 667 the temperature of ten children born at the full time was 34°,7o c. (94°,5 F.) ; the tempera- ture in no case descending lower than 34° (94° F.)> and ranging between this and 35°, 5 c. (96° F.). Let it be Observed that at the seventh month the membrana pupillaris no longer exists ; the infant has, therefore, at this epoch of its development, the essential charac- ters of warm-blooded animals capable of sup- porting a high temperature when that of the surrounding; atmosphere is mild. But if it were entering the world some considerable time before the disappearance of the pupillary mem- brane, it would be in a condition analogous to the Mammalia which are born with their eyes shut ; it would no longer be in a condition to maintain an elevated temperature, and without doubt would lose heat precisely as they do without precautions to the contrary. When we take a general view of the first and second periods in the early life of warm-blooded animals, we find that they are under the influence of two general conditions relative to calorifica- tion ; conditions which, acting inversely, tend to compensate each other mutually ; on the one hand, the celerity of the motions ; on the other, the imperfection of the nutrient and ner- vous functions. The celerity of the motions of circulation and respiration diminishes, whilst the development of the nutritive and nervous functions increases with age. These two con- ditions influencing the production of heat are, therefore, in an inverse ratio to one another. And according to the nature of these relations will the temperature vary. Were the opposite effects equal, there would be exact compensa- tion in the whole phases of the evolution, from the moment of birth to that of perfect adole- scence, and the temperature of the body would be the same at every period of life. But the progression in the celerity of the movements on the one hand and of corporeal development on the other, is unequal ; and there is but a single epoch in the whole course of childhood when such an equality or balance exists, and at which consequently the temperature of the child is the same as that of the adult. Previous to this epoch, the nutritive and nervous func- tions are so imperfectly developed, that their influence, inimical to the production of heat, surpasses the favourable tendency to this end, which we have in the celerity of the motions of circulation and respiration. It follows that the temperature of the body is inferior at the pre- ceding limit or to that of the adult state ; with the progress of time, however, the child attains this limit, and then we have a new relation established. The evolution of the nutritive and nervous functions continues, and although it have not yet attained its ultimate term, the de- fect of heat which results from this is all but compensated by the celerity of Use motions, which is still sufficiently great, to surpass in a marked degree the celerity of the motions in the adult. The temperature at this period will, therefore, be above that of the adult. This pe- riod lasts for several years in childhood or youth ; but then comes a gradual retardation in the motions both of respiration and circula- tion, and with this a reduction of the tempera- ture to the standard of the adult. There are consequently four states of the temperature from birth up to adolescence inclu- sive. In the first period the temperature is at the minimum ; in the second, it attains the adult degree ; this might be entitled the period of the mean temperature ; in the third, the temperature exceeds that of the adult; finally, in the fourth, it sinks to the mean, that is, the temperature of the adult. There are, therefore, constitutions in the same class of animals which are more or less favour- able to the production of heat ; for it is so among individuals that differ in age in the limits between the moment of birth and that at which adolescence is completed ; and this leads us to new considerations. DIFFERENCES OF CONSTITUTION IN RELATION WITH THE PRODUCTION OF HEAT AMONG ANIMALS. Since the body and the functions are pro- gressively developed, and without interruption between the two grand periods named, there is in the course of this long interval as much dif- ference in the state of the constitution as (here are sensible degrees of development ; a circum- stance that implies a long series of varieties. But these intimate differences are not mani- fested externally by corresponding states of temperature of body. For we have seen that this undergoes but four sensible variations in this respect, and that, of these four modifications, two were of like import. It is every way worthy of attention to observe that, at the point which separates the first from the second period of infancy, the temperature should be equal to that of the adult. It is difficult to imagine that this equality can exist under every variety of external cir- cumstance, when we see that the elements upon which it depends are so different. And this leads us to consider the production of heat under a new point of view. Under what cir- cumstances has this equality of temperature be- tween the infant and the adult been observed ? It was when the external temperature was mild or even warm. "Would the same thing have been observed had this been cold or severe ? It is evident that if the faculty to produce heat is the same at this period of infancy as it is in adult age, the heat of the body will always re- main the same, making abstraction of the diffe- rences that depend on those of simple corpo- real bulk. Thus, all things else being equal, a young animal at this epoch ought to cool to the same degree as an adult under the influence of external cold, if it have the same power of pro- ducing heat. Tf, however, it be inferior in its calorific powers, it will not be competent to maintain its temperature to the same degree as the adult, and it will fall under this limit in a proportion determined by the difference which exists in the faculty of producing heat. On making application of the principles which have been already announced, let us try if we cannot predict the effects. By reason of the inferiority in energy of the nervous system in 668 ANIMAL HEAT. early life, it is difficult to suppose that a young animal will resist the action of intense cold in the same manner as an adult. This inference is fully borne out by the following experiment. A young guinea-pig a month old, the tempe- rature of whose body was high and steady, the temperature of the external air being mild, was exposed along with an adult to the same degree of diminished temperature — the air was at 6°c. (32° F.). In the course of an hour the young creature had lost 9° c. in temperature, whilst the adult had only lost 2°,.5 c. This experi- ment, repeated several times with the same species of animal, always gave the same result. Young and adult birds of the same species, treated in a similar manner, showed the same diversity in their powers of resisting the effects of external cold, from which we may infer that the law is quite general. Several young mag- pies, for instance, whose temperature was sta- tionary in a mild spring atmosphere, were placed with an adult in air cooled to +4°c. After the lapse of twenty minutes, one of the young ones was found to have lost 14° of tem- perature. The others, examined at intervals, none of which exceeded one hour and ten mi- nutes in length, had cooled from 14° to 16° c. The adult bird, on the contrary, similarly cir- cumstanced, did not suffer a greater depression of temperature than 3° c. The loss of heat sustained by the young birds was so great as to be incompatible with life, if continued ; that endured by the old one was trifling in amount, and not inconsistent with health. It is quite true that the difference in point of size and quantity of plumage has an influence upon this inequality of cooling ; but at the period of de- velopment, when the experiment was tried, the difference was not remarkable in regard to either point ; nevertheless it is only proper to take notice of it. By prolonging the period during which the adults were exposed to the cooling process, the advantages they derive from their greater size and closer plumage may be counterbalanced or compensated. It is es- sential to observe that in the course of the fust hour the adult bird had only lost temperature in the proportion of one-fifth of that lost by the young birds, which obviously bears no ratio to the difference in point of size, plumage, &c. And then, the operation of the cold being con- tinued, the adult suffered no further depres- sion of temperature : it fell three degrees cen- tigrade, and then became stationary. We can- not, therefore, ascribe the entire difference in the cooling to that of the physical conditions of size and plumage ; a difference of constitution must go for a great deal ; there are inherent diversities of constitution, favourable or the re- verse, to the production of heat. The truth of this conclusion appears much more clearly if we continue to subject young birds to the same kind of experiment at successive epochs not so close to one another. The rapid progress they make in the power of evolving heat is, indeed, a very remarkable fact. A few days later, and they lose temperature in a much less considera- ble degree when exposed to cold under the same circumstances, although there was little or no apparent difference in the external appear- ance of the birds. And this is a new and con- vincing proof that the inequality in the disposi- tion to lose heat obvious at different periods of life under exposure to a low external tempe- rature, is principally owing to inherent inequa- lity in the faculty of producing caloric. It is of great importance that a precise idea be formed of this expression. Up to a very recent period in the investigation of animal heat, no one thought of comparing animals save with reference to the temperature of their bodies only : and when it was found that this was the same or different by so much, the ac- count was closed, the comparison was pushed no farther, under the impression that every thing was included under this single ostensible character. Undoubtedly, it must be granted that, all else being alike, equality of tempera- ture is an indication of equality in the capacity to produce heat. But animals in one set of circumstances may actually produce the same quantity of caloric, and not continue to do this the circumstances being changed. It is of consequence to distinguish the actual produc- tion, from the power to produce under different conditions. The one is an act, the other a fa- culty, a distinction of the highest importance in philosophical language in general, and espe- cially in that of physiology. But animals of the same size, subjected to the same variations of external conditions, if they continue to ex- hibit corresponding degrees of temperature, whether these are higher or lower, have evi- dently the same faculty of producing heat. If, on the contrary, they present different degrees under the influence of precisely similar exter- nal variations of circumstance, it is obvious that they must possess the faculty of producing heat in different degrees. Unless we be actu- ally persuaded of the value of this expression, so simple in other respects, and so constantly held in view in all analogous circumstances, the study of the phenomena of animal heat would remain as it were barren, whilst the in- vestigation of the diversities of constitution in relation with this faculty is fertile in interesting and useful applications. We have seen how constitutions differed in this respect according to age in the earlier period of life and in the adult state. It is probable that there are other varieties depend- ent on other causes ; for example, differences of season, climate, &c. This point it will be our next business to examine. INFLUENCE OF SEASONS IN THE PRODUC- TION OF ANIMAL HEAT. The temperature of an animal is the result, 1st, of the heat which it produces ; 2d, of that which it receives ; 3d, of that which it loses. The proportion of heat which is lost depends on two principal conditions, the relatively colder temperature of the atmosphere, and the amount of evaporation that takes place from the surface of the animal. In cold and tem- perate climates these two conditions of cooling are in inverse relations to one another in the opposite seasons of winter and summer. In ANIMAL HEAT. 669 winter the temperature of the air is lower ; in summer the amount of evaporation greater. These two conditions of refrigeration, therefore, tend to compensate one another, and conse- quently to maintain the equilibrium of tempe- rature as regards the body in the two opposite seasons. They have unquestionably a consi- derable share in this business ; and it was long believed that the simple difference indicated in the external conditions sufficed to preserve the temperature of the body alike during the two periods. But in reflecting on the phenomena presented by cold-blooded animals with the changes of the seasons, which have already been spoken of at length, we find such an opi- nion or view to be inadmissible. For in ex- amining those species of cold-blooded animals which from their structure are liable to lose more by evaporation than any other animal, we see that no such compensation takes place. Frogs, lor example, the skin of which is so soft and permeable, and whose bodies besides are so succulent that they must be presumed in the most favourable circumstances to sustain loss by evaporation, ought to preserve the same temperature in winter and in summer if the low temperature in winter were compensated by the excess of evaporation in proportion as the heat of the season augments. But we know that the temperature of these creatures follows, to a very great extent, that of the at- mosphere, between 0° and 25° c. (32° and 77° F.), diffeiing at no time from it by more than a degree or two. The phenomenon here is sim- ple, by reason of the slight evolution of caloric by the frog, and leaves no doubt upon the mind. We must, therefore, have recourse to other conditions, in order to explain the slight difference that is observed in the summer and winter temperature of man and other warm- blooded animals. Since external conditions do not appear to explain the phenomena, it must undoubtedly mainly depend oncertain changes effected in the animal itself. Now, since the internal conditions which influence the temperature of the body are those also that regulate the production of heat, it is here that the change must be effected. It is obvious that the cause of refrigeration in winter being more active, to meet the greater expenditure there must be the means provided for furnishing a larger supply — the calorific faculty must be more active in winter than in summer. Hie inverse of this takes place in summer ; so that the temperature of the body in the two seasons is determined in the follow- ing manner: — in winter there is a more active production with a greater loss ; in summer a less production, with a smaller loss of heat. In this way is there compensation, and a perfect equilibrium maintained at all seasons. To render this relation more evident, it may be expressed in another manner ; as, for example, in summer the body receives more heat from without, and produces less ; in winter it receives less and produces more. These considerations carry us farther. As this difference in the production of heat lasts as long as the various seasons, and lakes place progressively, it is to be presumed that it be- longs to an intimate and more or less en- during change effected in the state of the body. In other words, the constitution alters, and the faculty of producing heat changes in the same degree. The fact thus expressed is immediately susceptible of an interesting ap- plication. If the faculty of producing heat is less in summer, the temperature of the body will not be maintained to the same point in the two seasons under sudden exposure to the same degree of cold. By subjecting animals to the test of experiment in the two seasons, it is easy to judge of the justice of the preceding deductions, as well as of the principles which led to them. To have the mode of refrigera- tion precisely the same, attention must be had not merely to the thermometric temperature of the air, but also to its humidity, which ought to be the same in both instances. A difference in the hygrometric state of the air will certainly produce a difference in the effects of refrigera- tion. The apparatus employed consisted of earthen vessels plunged amidstaquantity of melt- ing ice. Air thus cooled soon reaches the point of extreme humidity. The air being at zero c. (32° F.), the animal is introduced, placed upon a stage of gauze to prevent its coming in con- tact with the moist and rapidly conducting surface of the vessel. A cover, also piled over with ice, is then placed over the apparatus, but so arranged as still to permit the ready reno- vation of the air contained in the interior. Still farther to secure the purity of the included air, a solution of potash, which of course ab- sorbed the carbonic acid produced with avidity, occupied the bottom of the vessel. In winter, in the month of February, the experiment was made at the same time upon five adult spar- rows, which were all included in the apparatus. At the end of an hour they were found one with another to have lost no more than 0°, 4 c, or less than half a degree ; some of them having suffered no depression of temperature whatsoever, others having lost as much as, but none more than, 1° c. The temperature of the whole then remained stationary to the end of the experiment, which was continued for three hours. In the month of July the same expe- riment was performed upon four full-grown or adult sparrows. The temperature of these birds at the end of an hour had undergone a depression, the mean term of which was 3°, 62, and the extremes 6°, 5 and 2° c. At the end of the third hour the mean term of the refrigeration suffered was 6°, the extremes being 12° and 3°, 5 c. It ought to have been stated that in the experiment in the winter month, the birds had been for some time kept in a warm room, so that the sudden transition was the same in both instances, in the winter as well as the summer experiment. The diver- sity in the constitution of these birds, conse- quently, with reference to the powers of pro- ducing heat, was an effect of the difference of the seasons. Each month the temperature of which differs in any degree from that of the month before or after it, has an obvious ten- dency to modify the temperament or constitu- 670 ANIMAL HEAT. tion in the manner which has been indicated. In summer we may presume, nay we may be certain, that the differences obtain in degree according to the mean intensity of the heat proper to each. This is even to be proved by direct experiment. The month of August, as commonly happens, was not so hot as the month of July, and six sparrows treated in the same manner as those that were the subject of the July experiment already detailed, were found not to suffer refrigeration to the same extent. After the lapse of an hour the mean temperature of the six had sunk 1°, 62, and after three hours 4°, 87 c, from which it is ob- vious that with the successive declensions of the external temperature the faculty of engendering heat increases. This is demonstrated by the experiments quoted. The animals that were the subjects employed suffered a relatively less degree of refrigeration in the cooler month than they had done in the hotter, when exposed to the same measure of cold. In the first set of experiments performed in one of the coldest months of the year, the power of resisting cold was made particularly manifest. The sparrows, kept for three hours in an atmosphere at the temperature at which ice melts, scarcely suffered any loss of heat at all. The results of the three series of experiments detailed confirm, in every particular, the conclusions which had been come to analogically and a priori. They do more than this. They bear out equally the principles which had been deduced with refe- rence to the constitutions more or less favoura- ble to the production of heat. It is apparent, in the first place, that the influence of the summer and that of the winter act on the con- stitution in the same manner as the two opposed periods of early youth and adult age. Let us therefore inquire in what manner these different conditions tend to produce analogous effects. We have seen that the constitution of early life differed from that of adult age, especially in the inferior energy of the functions of innerva- tion and nutrition. Now this is that which constitutes or causes the principal difference between the winter and summer constitution of man. We generally feel ourselves weaker in summer than in winter, and our digestive powers are then also decidedly less vigorous. What completes the analogy is that the motions of circulation and respiration are accelerated in summer; and as a complement of the whole of these data, the temperature is somewhat higher in summer; just as we have seen that there is an epoch in youth when the tem- perature exceeds that which is proper to com- plete manhood. Thus, the parity between the constitution of youth (in the second period of childhood,) and that of the body in sum- mer, contrasted with the constitution of the adult age and that of the body in winter, exists in the three following relations : — 1st, a lessened faculty of producing heat ; 2d, greater activity in the motions of circulation and respiration ; 3d, a higher temperature of the body. But this faculty of adaptation to the different seasons inherent in the body is only observed in the better constitutions. That it may be manifested, it is necessary there be present a certain energy of the nervous system ; without this even the moderate colds of winter will not be resisted. Without this the adult will have a constitution that will present analogies with that of early infancy. At present we merely mention the kind of constitution ; we shall return to the subject by-and- by. Differences according to the nature of the climate. — The preceding facts render direct ex- periments to ascertain the influence of the tem- perature of different climates on the calorific power altogether unnecessary. This is so far fortunate ; for it were no easy matter to institute them to the extent and with the precautions necessary to security and satisfaction. The knowledge of these effects is a necessary con- sequence of the researches that precede. The temperature of warm climates is represented by the summer temperature of temperate climates, with this difference, that it is higher, and that with slight variations it continues through the whole year. Whence it follows that warm climates taken generally must produce effects upon the constitution analogous to those pro- duced by summer with us, only of greater intensity by reason of the higher thermometric range and longer continuance of the heat. The inhabitants of hot climates ought consequently to have an inferior degree of calorific power than those of temperate or cold countries, what- ever be the season. And we find, in fact, that the natives of the warmer latitudes of the earth present the characters in general that distinguish the constitution of the body in the summers of temperate countries, and characterizes the second period of youth — more rapid motions of the circulatory and respiratory systems, and a higher temperature, conjoined with an inferior degree of energy in the functions of innervation and nutrition. We shall not here enter upon the examina- tion of the effects upon the natives of these warmer latitudes from change of climate. We shall speak of this elsewhere. After the periodi- cal changes depending on the seasons we shall pass to others of shorter duration, but which revert much more frequently, and are under the influence of other causes. INFLUENCE OF SLEEP ON THE PRODUCTION OF HEAT. In the course of the twenty-four hours the body is in two very different and in some sort opposite states — the states of sleeping and watching. These two states are principally contrasted in the energy and weakness of the nervous system: from a perfect consciousness of all that is passing, we suddenly observe a complete suspension of this office in the whole circle of the functions of relation. At the same time the motions of the circulatory and respira- tory system become slower. No more is needed to lead to the conclusion that in this state the temperature must be lower; this is an inference we draw without risk of error. But the degree in which these motions are retarded is ex- tremely limited ; and the depression of tem- perature must be expected to be in the same ANIMAL HEAT. 671 proportion : it is in fact very slight, although appreciable. What would happen were the retardation in the important motions mentioned more considerable? The temperature would suffer a corresponding and great depression, and various consequences might be conceived as calculated to ensue. If the degree of cold did no injury to the economy, the sleep would last the time required to repair by rest the energy which the nervous system had dissipated or lost by its activity during the period of watching. If, on the contrary, the refrigeration attained a considerable degree, it would by the consequent pain stimulate the nervous system so much as to cause it to wake up to general consciousness; but in case the nervous system were not in a condition to feel this excitement, in other words to re-act and produce waking, it would sink into the state of lethargy. These divers states which we deduce as pos- sibilities, as what might be expected to occur in sleep according to the relations of the func- tions, do in fact present themselves frequently in nature. It commonly enough happens that we are aroused from our sleep by a feeling of cold, although the external temperature has not changed. With regard to the lethargic state, although it certainly occurs but rarely, still it has been acknowledged by the most respectable authorities, and its occasional occur- rence seems indubitable. That, however, which is rare as regards man may be common and even usual as animals are concerned. Phenomena presented by hybernating animals with regard to the production of heat. — If during the height of summer and during the state of watching a dormouse or a bat be exa- mined as to their temperature, this will be found the same as that of many other warm- blooded animals. But if either of these animals be examined whilst asleep at the same season of the year, the temperature will be found to have declined considerably. These changes have been determined by Dr. Marshall Hall, to whom we are indebted for manv ob- servations of high interest upon the state of the circulation in hybernating animals. The writer also observed the same diversities in the temperature of these animals according to their state of sleep or watching; but he had not published his observations at the time Dr. Hall's paper appeared. Here, then, we have several species of warm-blooded animals which, during the hottest season of the year, exhibit in the two states of sleep and watching a very marked contrast in regard to the temperature of their body, which is high during the waking period, low during that of sleep, the external temperature having no part in the phenomena. The difference of temperature coincides very evidently with the state of the nervous system — its energy in watching, its enfeeblement in sleep — a state which we have already seen to influence in a very great degree the rapidity of the motions of circulation and respiration, which are accelerated during the energetic con- dition, retarded during the period of inaction. A higher temperature in the one case and a lower temperature in the other are necessary consequences. These facts are interesting under two points of view. 1st, They show precisely the kind and extent of the influence which the states of watching and sleep exert in general on the production of heat in animal bodies; 2d, they are remarkable in the particular instances under consideration, in this, that the differences exhi- bited during the two states are extreme. It must be allowed, therefore, that those animals in which they take place must have less energetic nervous systems than other warm- blooded animals. From this tendency in the animal economy, there must also be in different species a diversity rather than an equality in the degree in which the phenomena are exhibited. And this is confirmed by obser- vation. Some cool to a much greater extent than others during their sleep in the summer season. They may be said severally to have just as much nervous energy as is requisite to sustain a high temperature in the summer season during their state of highest activity, i. e. during the period of watching, and no more. When the state of excitement ceases, and the collapse that follows excitement supervenes, the languor manifested is much greater than that of other animals in the same condition, and their temperature sinks in proportion. The energy possessed by hyber- nating animals seems barely sufficient to enable them during the summer season to maintain a temperatureof body equal tothatof warm-blood- ed animals in general. They subsequently pre- sent another phenomenon with regard to their temperature well worthy of particular attention, although it be no more than a consequence of the first. Since it is a defect of energy in the nervous system during sleep which prevents their maintaining the degree of rapidity in the motions of circulation and respiration so essen- tial in their turn to the maintenance of a tem- perature of the body but little inferior to that pertaining to the state of watching in summer, how are they to preserve their temperature even during the watching state when the summer declines into autumn, and the autumn into winter? It is evident that if they follow the general rule their respiratory and circulatory motions will be retarded with the fall of the atmospheric temperature, and this by so much the more as their nervous system shows a less degree of energy. It is even presumable that owing to the decline of atmospheric temperature in autumn, they will exhibit a temperature of body during the period of watching analogous to that which they manifest in the heat of the summer season during sleep. And this is pre- cisely what happens. M. de Saissy paid par- ticular attention to the state of these animals at intervals from the month of August onwards. On the 6th of August, the temperature of the air being at 22° c. (72° F.), a dormouse and a marmot marked 36° 5 (98° F.), and a hedge- hog 34° c. (93°, 5 F.) in the axilla. On the 23d September, the external temperature being 672 ANIMAL HEAT. 18° (64°, 5 F.), the temperature of the hedge- hog was lower by 2° c, that of the marmot by 5°, 25 c, and that of the dormouse by 5°, 5 c. than it had been at the previous date. This is a considerable depression, if it be remembered that the decline in the atmospheric temperature was by no means considerable ; that the air was in fact still at a point which made it be felt as warm to the generality of persons. The same individual animals examined on the 7th of November, the atmospheric temperature being 7°, presented the following state. The mar- mot had lost 9°, 25 c, the dormouse 15°, 5 c, and the hedge-hog 21°, 25 c. of their respec- tive temperatures during the month of August, so that their absolute temperatures were now as follows: that of the marmot 27° (81° F.), that of the dormouse 21° (70° F.), and that of the hedge-hog 13°, 75 c. (57° F.). Here, there- fore, we have several warm-blooded animals which in autumn approach very closely to the cold-blooded tribes with regard to their calorific power. If they be next observed during the period of sleep, the relationship will be observed if possible in a more striking degree. If, during the state of watching, they surfer such a loss of temperature as has been specified with the gradual decline of the temperature of the year, they will certainly suffer still more remarkable changes during the state of sleep, in conforinity with the principles already fully developed. The sleep of these animals will also become longer and deeper in proportion as the nervous system loses its power, under the influence of the external cold, a loss which will be mani- fested by a farther retardation in the motions of circulation and respiration. But what is the increasing weakness of the nervous system during sleep but a more or less marked state of torpor ? The same degree of cold con- tinuing, or the degree of cold becoming gra- dually greater, the disproportion as regards the animal will increase also, and will necessarily attain a term at which the torpor during sleep will become lethargic. If the external temperature goes on declining, and attains a point at which it becomes dangerous to the life of the creature, the cold, within certain limits, ought to have the power of withdrawing the animal from its state of lethargy. The excite- ment which appertains to the waking period, by accelerating the motions of circulation and of" respiration, will then cause the temperature of the body to rise. But if the external tem- perature does not become more favourable, or if the animal finds no means of abstracting itself from its influence, it has not sufficient resource within itself and must perish. We have seen above that the changes in the seasons produced great modifications in the constitution of wann-blooded animals in gene- ral. But it were difficult to imagine any greater or more striking than those presented to us by the species which we have just named, which belong to the family of hybernating animals ; changes which arise from their passing the winter months in a state of lethargy. When these animals are recalled from this state to- wards the end of autumn, and during the course of the winter, they may seem to resume the characters which distinguish the vitality of warm-blooded animals in general, but they are in a very different state at this epoch from what they are in summer. Their constitution has un !ergone important changes, which it is necessary to examine and appreciate exactly. These changes are inversely as those which the most perfectly constituted warm-blooded ani- mals experience. These, under the influence of the increasing cold of autumn and winter, acquire new vigour, and their faculty of pro- ducing heat increases in consequence. Those, on the contrary, naturally much less energetic even at the most favourable period of the year, require to be excited and supported by the high temperature of the summer or warmer months, to permit them to exhibit all their activity and strength. It is in the warm season of the year that these animals have the greatest degree of energy — energy which has a certain duration even after the external conditions which have developed it have ceased to operate ; for they have been as it were tempered by the continuity of favourable circumstances, espe- cially of the high atmospheric temperature. This is the reason why they are so slightly affected by the diurnal variations of the warm season of the year; and even when this begins to wane, and they are no longer stimulated by the temperature proper to summer, they find sufficient energy in the store accumulated, as it were, during the fine season to enable them to resist for a time and to a certain extent the unfavourable influences with which they begin to be surrounded. These continuing, however, and even increasing, they gradually yield to their influence, and sink lethargic, till revived by the return of spring with its milder tempe- rature. Their languor even augments not only with a progressively lower degree of atmospheric temperature, but with the persistence of a degree which in itself is not by any means excessive. These hybernating animals, whilst they pre- sent the structure of the warm-blooded tribes in general, still approach in a very remarkable degree to the cold-blooded tribes in their defective energy, or their indifferent powers of reaction. This is to be regarded as the prin- cipal source of the phenomena they exhibit in the current of the year, phenomena which are unknown among the more perfectly con- stituted warm-blooded animals, but which are absolutely of the same nature as those presented by the cold-blooded Vertebrata in the same circumstances, and which only differ in degree. This analogy or resemblance in the phenomena appears to arise from analogy not of structure but of constitution. Very opposite organiza- tions may have analogous constitutions ; cold- blooded animals for example present the greatest diversities of structure, and all are affected and bear themselves in the same man- ner under similar circumstances in very many respects. They have thus a common constitu- ANIMAL HEAT. 673 tion which characterizes them, the fundamental principle or distinguishing feature of which is a defect of energy, or of power of reaction. This principle, so simple in itself, and which is but the true expression of the various facts reduced to unity, renders plain and obvious much that otherwise appears anomalous or contradictory. In studying the phenomena of animal heat under new relations, we shall find the confirmation of what precedes. Of the system upon which the external temperature acts primarily and prin- CIPALLY. Our sensations admonish us that it is the nervous system that is acted upon primarily and principally by changes of external temperature. In the first place the impression is felt instan- taneously ; in the second place the intensity of the sensation is in relation with the degree of external heat or cold ; in the third place the im- pression is not limited to the various degrees of the corresponding sensation of heat or cold ; it extends to the other faculties of the nervous system, increasing or diminishing the general or special sensibility ; in the fourth place it acts powerfully in increasing or diminishing the activity of the muscular system, principally through the medium of the nervous system. Influence of temperature on the vitality of cold-blooded animals. If the functions of respiration and general circulation be destroyed by the excision of the lungs and heart of a cold-blooded animal, of one of the Batrachia for example, life may still continue for a time. Of the three principal systems of the economy the only one then left untouched is the nervous ; so that the animal may be viewed as living almost exclusively by the agency of this system. If several animals in this condition be plunged in water deprived of air, they will live in it different spaces of time according to the degree of its temperature, the extremes compatible with their existence being zero and 40 c. It is towards the inferior limit, zero, that they live the longest. Towards the upper limit they die almost im- mediately. Temperature, consequently, pre- sents in the scale of variations just mentioned very remarkable relations with the vitality of these animals. Towards the lower limit or that of melting ice, it is obviously most favourable to life; towards the upper limit, it is most inimical to life, extinguishing it almost immediately. Here it is impossible to mistake the system upon which the variety of temperature exerts its first and principal effects — the nervous system. If respiration only be annihilated by plunging these creatures under water deprived of air, the temperature of which is caused to vary as above, they will be found to present the same phenomena according to the degree of the heat or cold, but in a more striking manner. Temperature in this case has the same kind of influence, but the effects are more manifest, from the circulation of the venous blood prolonging life at every degree short of the one at the upper limit of the scale, at which life is extinguished quite as suddenly as in the former instance. Such are the direct and instantaneous effects of temperature upon the vitality of cold- blooded animals. But there are others which flow from its successive agency, during a con- siderable length of time. If the series of ex- periments just quoted be made in summer, and the different lengths of life at different degrees of temperature of the frogs immersed in water be noted, (between the limits which we have pointed out above,) and the same expe- riments be repeated in autumn, the length or tenacity of life manifested by the animals will be much greater at the same degrees of tem- perature— they will in general be found to live twice as long now as they did in summer, at corresponding and equal temperatures of the medium in which they are immersed. The depression of atmospheric temperature in the autumn has modified their constitution, and actually increased their vitality, precisely in the manner indicated above. The slight effects of each successive fall in the general temperature have accumulated in the constitu- tion so as to render their vitality or tenacity of life much greater, a fact which is made abun- dantly manifest by the faculty of the animals to remain for a much longer time immersed in water without breathing than they could have done in summer. If a third series of experi- ments of the same description be made in winter, the tenacity of life will be found to have increased in a very high degree. At the same degree of temperature frogs will be found to live immersed in water deprived of its air at least twice as long in winter as they could have done in autumn. The same cause — the depression of the atmospheric temperature — has continued to act with greater intensity and for a longer period, and the constitution, gradually modified by greater and longer con- tinued cold, has acquired greater tenacity of life. The opposite effect takes place with the successive rises of the temperature from that of winter to that of summer ; so that among cold- blooded animals the maximum of vitality, i. e. tenacity of life, corresponds to the depth of winter, the minimum to the height of sum- mer. The slight and from moment to moment inappreciable effects produced by the external temperature, whether tending to increase or to diminish the vitality, accumulate with their repetition through the period of each season, and produce a corresponding change in the con- stitution with regard to tenacity of life. These accumulated effects of the different portions of the year constitute the influence of the seasons on the constitution with respect to many of the most important relations of life. The first of these we have just examined cursorily — that is, the faculty of living in air according to the influence of the actual temperature, or of that of the past temperature, in other words the season that has immediately preceded. The second of these fundamental relations consists in the various proportions of air necessary to 674 ANIMAL HEAT. the maintenance of life according to their re- lations with the temperature. We have seen that it is at the minimum of temperature that the cold-blooded animals possess the greatest tenacity of life, as regards the most essential relation, in other words they are in the con- dition the most favourable to enable them to do without air; at this point they are in a state to live for the longest time without breathing. It is obvious that here they must require less air than under any other circumstances ; they must necessarily require so much the less, as their life will continue longer here than under any other circumstances without any access of air at all. It is, however, essential to appre- ciate duly this fundamental relation, namely, that at the lower limit of the scale of tempera- ture mentioned, cold-blooded animals require less air to live, and what is more, they con- sume less air than under any other circum- stances, and are even incapacitated from con- suming more than they do. The minimum temperature of this scale consequently is an index of the maximum of vitality or tenacity of life, and at the same time of the minimum of respiration. In the same proportion as the temperature rises, the vitality or tenacity of life declines, which makes it necessary that this declension should be compensated by a corresponding increase in their relation with the air, in order that the vivifying influence of this fluid may neutralize the deleterious effects of the increase of heat. And this is what actually happens. With the rise in tempe- rature the sphere of activity of the respiration extends, and the vivifying influence of the air, which increases with the quantity of the fluid consumed, compensates the successive decre- ments in vitality or tenacity of life, dependent on successive increments of temperature. We shall therefore express in a very few words this fundamental relation between the tempera- ture of the air and the maintenance of life among the invertebrate series of animals, — a relation entirely deduced from direct experi- ment, which we can but refer to here, but which we shall lay before our readers with all the requisite details in our article on Respira- tion. The rise of temperature in the scale from zero to 40 c. exerts upon the nervous system of cold-blooded animals an action the tendency of which is to diminish its vitality; the air, on the contrary, exerts a vivifying in- fluence on this system. It becomes necessary, therefore, to the maintenance of life that their respective relations with the economy be such that their effects compensate or counterbalance each other. The principle relative to the influence of temperature on the vitality of cold-blooded animals just laid down, is applicable in every particular to the changes experienced and the phenomena presented by the hybernating tribes among the warm-blooded series of animals. Their vitality changes with the wane of the year, i. e. under the influence of prolonged exposure to cold, in the same manner They are then in a condition to exist with a supply of air by so much the less as this influence has been more intense and more protracted,; and precisely as the cold-blooded tribes, if entirely deprived of air in winter, they will live for a much longer time in this deleterious position than they would have done in summer. Influence of temperature on the vitality of warm-blooded animals and of man in the states of health and disease. These principles and considerations lead us to examine what happens among warm-blooded animals in the same circumstances. There being great and manifold analogies between them and the preceding tribe of animals, there must also be some community in the application of the principles laid down; but as they also differ in many important respects, this application must be correspondingly restricted. In the first place, then, there is complete analogy between the one and the other with regard to the influence of the superior thermal limit on the vitality of the nervous system. To seize the analogy properly, it is however necessary to regard the temperature which modifies this system in each series, from a point of view that is common to both. Whether the temperature proceeds from without or from within, we may presume that it will influence or modify the nervous system in the same manner, if not to the same degree, inasmuch as this system presents differences. Warm-blooded animals having in general a high temperature at all seasons of the year, they must be compared in this respect with cold-blooded animals in the height of summer. On the one hand, heat within certain limits tends to increase sensibi- lity and motility ; warm-blooded animals, therefore, with a few exceptions, which always present a high temperature, constantly exhibit also, with a few exceptions, a high, degree of sensibility and motility. The same thing can only be said of the cold-blooded tribes during the continuance of the warm weather. On the other hand, again, high temperature tends to lessen the vitality proper to the nervous system, or the faculty of living without the agency of the ordinary stimuli. This is also the reason why, if respiration be interrupted among warm- blooded animals at all times, and among cold- blooded animals during the warmer seasons of the year, they all perish alike speedily or nearly so. The difference in the time that elapses before life is extinct still depends on, or is in relation with, the difference of temperature. For in the hotter season of the year, cold- blooded animals never attain the temperature of the warm-blooded tribes, even in the most burning climates of the globe. Their nervous system will consequently have a higher degree of vitality in the sense already indicated ; that is to say, they will not perish so promptly in summer under deprivation of air ; but if they be immersed in water at the mean tempera- ture of warm-blooded animals generally, which is about 40° c. (104° F.), they will die as sud- denly— (at least this is the case with those of small size upon which the experiment has been made) — as the warm-blooded Vertebrata when deprived of the contact of air. ANIMAL HEAT. 675 The analogy on either hand consists in the effects of temperature. But the differences that must necessarily occur between natures that vary in so many other respects are espe- cially encountered in the dissimilar effects of cold. Here we observe a general compensa- tion which distinguishes in tVie most marked manner the Vertebrata having a constant or all but a constant temperature, from the hyber- nating tribes or Vertebrata whose temperature varies, and the cold-blooded series generally. The relation of cold, or of a low temperature relatively to the standard of the more perfect beings of creation, is one of essential impor- tance, and requiring our most careful investi- gation. Cold, as has been said, tends to diminish sensibility and motility; but cold itself is per- ceived by causing a diminution of the general sensibility ; among animals of superior organi- zation it even acts indirectly as a stimulus : the blood flows into the parts that had been chilled, if their temperature has not fallen too low, for then all sensibility is extinguished and reaction never occurs. The afflux of blood to the external parts is manifested by the increased redness ; and the skin becomes red in proportion as the parts it covers are susceptible of acquiring a high temperature, such as the hand. We have shown that the consequence of the afflux of blood is an in- crease of temperature which tends to counter- balance the effects of the refrigeration. The compensation, however, is not perfect. For m winter the temperature continues above that of summer, although there is a greater pro- duction of heat in winter than there is in summer, as we have shown above. The constitution of the Vertebrata having a nearly constant temperature differs essentially in the power of reaction it possesses ; a power which cannot better be expressed than by the word energy, and which must necessarily be referred to the nervous system. The power of reaction under the influence of cold is exhi- bited in two modes : the first is that which has just been mentioned, in which the stimulus of the cold calls the blood into the capillaries of the surface, without exciting any kind of vio- lent motions in the circulating and respiratory systems ; the second consists essentially in this last kind of excitement. The sharpness of the cold stimulates the respiratory motions, which become accelerated, and the quickening of the motions of the heart follows or accom- panies those of the lungs. These two modes of reaction must be viewed as two degrees of the same power : 1st, an afflux of the blood to the capillary vessels ; 2d, acceleration of the motions of the thorax and heart. There is, however, between these two processes a diffe- rence which it is of the greatest conse- quence clearly to understand. The first, so long as it remains within certain and suitable limits, is a reaction that maintains the eco- nomy in a stale of health. The second tends to produce salutary effects, but becoming ex- cessive it brings the body into a state of disease. The first is sufficient to enable those creatures whose system is energetic to resist the effects of rigorous cold, by preserving their general activity and the normal state of their functions. The second is the resource of those animals, which, although of the same species, are so constituted that the energy of the nervous sys- tem is less than in the former. This is what occurs universally in very early life. It is a reaction the tendency of which is salutary, but which is not the less on this account the index and essence of a proper pathological state. It is one of the cases in which the vis medicatrix natura is peculiarly and most strikingly manifested. This position is made singularly evident by the following experi- ment:— when a young bird, bare, or but scan- tily covered with feathers, is taken from the nest, and exposed to the open air, even in the summer season, its respiration will be seeu to be accelerated in the ratio of the cold it expe- riences. It is peculiarly worthy of remark that this salutary reaction, taking place under the influence of the nervous system, acting, in the case quoted, independently of the will, is in a great measure the same as that which we bring into play by means of the will to com- bat the same evil. When in health, for instance, we are exposed to and feel the impression of cold severely, and have no resource but in our- selves, we begin immediately to take exercise, and move about; and if we do this with sufficient vigour, the motions of respiration and circula- tion are very soon increased in rate, and our heat returns ; it being always understood that the external cold is not at too rigorous a degree. From what precedes, we are in a state to appreciate the part which each func- tion has in causing the developement of heat by exercise. The experiments of Messrs. Bec- querel and Breschet, referred to in an early part of this paper, have proved that the con- traction of the voluntary muscles is accom- panied by the evolution of caloric, and that the heat increases by a succession of muscular contractions. The first source of the heat evolved in exercise, therefore, lies in the con- tractions of the muscles, that is, in the volun- tary motions. These, vigorously called into play, are followed by increased rapidity in the action of the muscles of respiration, and of the central muscle of circulation, the heart ; and these, by the increased energy they impart to the functions over which they preside, cause an increase in the temperature in conformity with the general principles already laid down. It is well to follow the effects of exercise in the various modifications under the influence of cold. They produce phenomena which extend farther than the state of health, and which ap- pear in other conditions and circumstances from analogous reasons. Exercise, according to its degree and the degree of temperature of the external air, is adequate not only to compensate a chill, and to restore the body to its pristine temperature in every part, but even to do more than this. If the exercise has been sufficiently prolonged, but not been excessive, it may be suspended ; and the body, now re- stored by its means to its temperature, will be 2 v 2 C7G ANIMAL HEAT. apt to retain it longer than it had clone when exposed to cold without any preparation of the kind implied ; it will resist impressions of cold longer after exercise than it would after a state of perfect quiescence ; the nervous system has acquired new energy ; the economy is in a condition to react with greater effect than when depending on the process just described, that, namely, which takes place independently of the agency of the will. The repetition of the effects that follow exercise taken at due in- tervals, hardens the frame to such a degree that the body at length acquires the power, by means of the insensible and involuntary reac- tion alone, to resist degrees of cold which it could not have borne without the violent and voluntarily induced reaction of active muscular exertion. The different states of the body in the cir- cumstances just referred to deserve special attention, because they are reproduced in others, where the cause not being apparent they seem to be spontaneous, though they are in fact, as we shall have occasion to see, under the influence of an analogous cause. We sup- pose that on the first exposure to cold during rest, the reaction from the afflux of blood to the capillaries is slight, and that the cold is even sufficiently intense to produce an opposite effect, that is, paleness of the part chilled. To this symptom of the action of cold, shiver- ing is superadded in various degrees of inten- sity. If recourse be now had to exercise, this state will last for a period long in proportion to its intensity, until violent and prolonged mo- tion have restored the temperature. If the exercise be continued, the heat increases, and even rises above its degree at starting ; in this case it first restores the proper heat of the skin, and then causes this tegument to assume a red colour, which may become extremely intense. To this second state succeeds a third, in which the skin, which had hitherto been dry and un- perspiring, becomes soft and finally bedewed with moisture. Here, then, we have three different states induced under the influence of cold acting at first without opposition on the part of the system, and then combated by powerful and voluntary reaction. First, we have coldness, palene?s,and shivering; secondly, heat and redness; thirdly, moisture of the skin and sweating. In making the application here of what has been said above upon the repetition of these acts, we perceive that at the same degree of external temperature the effects which at first, and under other circumstances, would follow the impression of such a degree of cold, may cease to be felt. This happens from the constitution having improved under the actions and their effects, which have been detailed, and that it is in a state, with the assistance of its own inherent powers of insen- sible and involuntary reaction, to resist refrige- ration. But do we not, when we strengthen the constitution to such a pitch as enables it to resist an influence which was a cause of incon- venience to it previously, cure it of an infir- mity ? It is obvious from what precedes that the temperature of the body may be indiffe- rently affected, either by a great fall in that of the air, or by an insufficient production of heat. The temperature of the body tends to sink equally when, producing a great deal of heat, it is exposed to severe cold, or when, producing little heat, it is exposed to a moderate warmth. In either case the effects upon the economy will be analogous without being identical. In each case there will be a keen sense of cold according to the depression of the external temperature on the one hand, or the slightness of the evolution of heat on the other. In the latter case the insensible reaction will be ex- tremely limited, as well as the voluntary reac- tion, on account of the deficient energy. But there are still resources within the economy. It is then that the involuntary and violent reaction of which we have already spoken takes place. The circulation and the respiration increase in rapidity spontaneously. In the case which we have just supposed, there will be certain series of phenomena, analogous to those we have described as occurring in the instance of a strong individual exposed to the influence of severe cold, who suffers from it at first, and subsequently opposes and vanquishes it by means of a violent and voluntarily superinduced reaction. When the faculty of engendering heat sinks to a certain term, there will be not only a vivid sensation of cold even in summer, but all the other consequences of exposure to a low temperature, such as paleness, shivering, &c. ; by-and-by the involuntary reaction will not fail to take place; the respiration and circulation are accelerated, and end by restoring the temperature, if the lesion of the calorific power have not been too extensive, the skin being first hot and dry, and subsequently hot and moist. Here, consequently, we have the three periods precisely as in the case previously described : 1st, coldness, pallor, and shivering ; 2d, acceleration of respiration and circula- tion, accompanied in the second period by dry heat, and in the third by sweating. There is therefore the strongest analogy in the two cases. They resemble one another in the cha- racter of the phenomena, and the order of their succession. This is so obvious as merely to require mention ; there can be no occasion for more particular illustration. They have also the strictest relationship in their causes, without these, however, being identical. In the first case the individual produces a great deal of heat, but he cannot engender enough by the ordinary and insensible reaction, in conse- quence of which he has recourse to the violent and voluntary reaction, which soon produces the desired effect. In the second, the indivi- dual produces little heat, and the economy may suffer from this diminution of the calorific faculty to the extent of finding itself incapable of restoring a sufficient degree of heat by means of a violent and voluntary reaction. The violent and involuntary reaction then succeeds, and pro- duces all the effects of that which is put into play under the empire of the will. Nor is the resemblance limited to immediate results. It further extends to the remote and definitive effect. For in either case the violent effort ANIMAL HEAT. 677 ceases after a certain interval of variable extent, according to various circumstances; and a state of tranquillity comes on in which the body has recovered the faculty of engendering by the ordinary means the quantity of heat ne- cessary to the comfortable existence of the in- dividual. After this the repetition with greater or less frequency of the same acts ends by restoring the calorific function to the state in which insensible reaction suffices to maintain it in its sufficiency. In the first case it is a strong individual able to make the voluntary and energetic efforts required to remedy the inconvenience he suffers. In the other instance it is an individual who has not the strength requisite to make such efforts. In this case nature supplies the deficiency by exciting directly the motions of circulation and respira- tion by the painful impression of cold. Al- though the condition of the first be the state of health, and that of the second properly a morbid state, they nevertheless have many relations in common, which differ princi- pally in degree. Does not the robust indivi- dual experience an inconvenience for which he finds a remedy in violent and repeated efforts ? However robust he may be under ordinary cir- cumstances, in the extraordinary condition in which he is placed the usual vital processes no longer suffice him. He must have recourse to violent means which disturb the economy ; and by a repetition of the same efforts at diffe- rent periods, that is to say, in tits or paroxysms, he ends by so far fortifying hirnelf as to be able to do without them. Is not this tantamount to remedying a relative infirmity of constitution ? Let its degree increase but a little, and the infirmity becomes disease. This parallel is not founded on vague and superficial resemblances, but on determinate and fundamental relations. There is not one essential point in the compari- son which does not rest on the result of direct experiments, most of which have been quoted in preceding parts of this article. What must be done to justify the similitude of these two stales ? With regard to the state of health the connexion of phenomena having reference to the hygienic and voluntary reaction is well known. With reference to the relation between the symptoms in the morbid state and the morbid reaction, it remains to be proved that under circumstances where there is but slight production of heat, the feeling of cold may induce acceleration in the respiratory and circu- latory motions. Now it has been established by experiments already quoted, that there is reac- tion of this precise kind in such circumstances. We have seen, for instance, that when a bird, naked or scantily covered with feathers, is taken from the nest and exposed to the air even in summer, it speedily begins to shiver, and to exhibit a reaction in accelerated motions of respiration, which is followed by, and indeed implies increased rapidity in the motions of the heart and current of the blood. It were also proper to show that the cold state may, by means of the violent and involuntary reaction, induce the restoration of heat. This is also susceptible of proof by means of direct expe- riment. To this end an individual (a young bird from the nest) must be chosen of such an age that the temperature will not be apt to fall too low on exposure to the air. If the choice have been fortunate, it will be found that the temperature sinks in the first instance, and then rises, so that it may even surpass the de- gree it showed at first, under the influence of the reaction occasioned by the acceleration of the motions of respiration and circulation. The proof here is, therefore, extremely satis- factory. A creature in a state of health is taken and placed in circumstances in which the same essential symptoms are produced in the same order as in the morbid state which we have described. It can scarcely be necessary to say that the morbid state which we have described in man is that of simple intermittent fever. Not only in the beginning of this disease is there a feeling of cold, but recent accurate ob- servations have shown, by means of the ther- mometer, that there is actual refrigeration. There is, therefore, lesion of the calorific func- tion in the sense previously indicated, that is, there is decrease in the power to produce heat. Subsequently the temperature rises whilst there is still more or less of the sensation of cold remaining ; but this only happens by vir- tue of a general disposition of the nervous system. The same thing, in fact, occurs in a state of perfect health ; when the body has for some time been exposed to severe cold, the sensation continues for a certain interval after it has been restored to the normal temperature. It is of little consequence, as regards the sub- ject which engages our attention, that there are some intermittent fevers which do not exhibit the phenomena of temperature that have been described. We are only interested in proving that some do occur which present them all, — a fact that has been demonstrated by the best authorities. There is consequently in these cases a lesion of the calorific function, a lesion of which the essence consists in a diminution of the faculty of producing heat. In a constitution capable of re-acting by the acceleration of the respiration and circulation, we may observe upon this occa- sion two principal modifications of the morbid state, which both depend on the same cause, but which differ in degree. The first is that described in which the reaction suffices to restore the calorific power to the degree com- patible with health after one or more fits or paroxysms. With regard to the second, the diminution of the function of calorification may be so great, that the reaction may prove in- adequate to restore it, not only permanently but even momentarily. Theie are in fact diseases of this kind ; there are many regular intermittent fevers that have no tendency to spontaneous cure ; there is also one particular form of the disease which proves speedily fatal without the intervention of art. This is that form of intermittent which is known at Rome especially under the name of ihej'cbbrc qlgidq, or cold fever. It often happens that the patient, 678 ANIMAL HEAT. unless suitably treated, dies in the cold stage of the second or third paroxysm ; sometimes he will even perish in the first. It is easy to produce at will the essential symptoms of these affections even in their most formidable shapes, in animals in a state of health. All the young birds, for example, belonging to the group of those which at their birth have the weaker calorific powers, can be made to exhibit the phenomena in question. If, at the period of their exclusion or shortly after this, they be taken out of the nest, we have seen that they lose heat rapidly even in the summer season ; and we perceive that any reaction of which they are capable by the acceleration of their respiratory and circulatory motions avails them nothing ; their tempera- ture sinks in spite of this, till all reaction ceases by the increasing and now benumbing influence of the cold, so that they speedily perish. In these two extreme cases of dimin- ished production of heat, there is similarity in the symptoms which ensue, with this difference, that in the algid intermittent there is lesion or a morbid state of the calorific faculty; whilst in the other case the scanty production of heat is a normal condition in relation with the age of the subject. In the first, the constitution is seriously altered ; it must be restored or other- wise the individual dies; in the second, there is no alteration of any kind ; the individual only requires to be placed in circumstances favourable to the normal manifestation of the function to be restored. In the one the lesion is so great that there is no resource in nature abandoned to her own efforts ; art must interfere. In the other, nature provides against the scanty production of caloric in giving to parents the instinct to warm their young by the heat of their own bodies, &c. We have seen that cold, when not of too great intensity, tended to strengthen the body by increasing the faculty of producing heat ; and farther, that with the progressive rise of the temperature in spring and summer the energy of this faculty diminished. This is what takes place with regard to those constitu- tions that are in the most favourable relation with the climate. Let us now examine the nature of those constitutions that do not adapt themselves thoroughly to the changes of the seasons, and see what the consequences are with regard to them. Let us begin with the rela- tion of these to the cold season of the year. It might be presumed a priori that those con- stitutions that have a very limited capacity of engendering heat will not accommodate them- selves well to the cold of winter. Their limited powers of producing heat will not ena- ble them to repair the continually increasing loss of it arising from the depression of the external temperature. They consequently suffer in a greater or less degree from cold, perhaps not to any great extent in the first instance, as we shall have occasion to explain by-and- by, but still in some measure ; and there are certain degrees of uneasiness and inconvenience that may be regarded as being still within the limits of health. There is even a certain, and that a pretty wide latitude in which the body may vary without trespassing on the line of disease. The uneasiness may only be ex- perienced from time to time, and not even be always very manifestly referable to its proper cause. In other words the sensation may be something quite different from that ordinarily induced by cold; just as it sometimes happens that among weak constitutions the necessity of taking food is not always proclaimed by the feeling of hunger, but occasionally by some other distressing or painful sensation, with re- gard to the true nature of which experience alone can enlighten us. In such a low state of the calorific power, the faculty seems to lose strength still further, owing to the simple per- sistence of the same degree of cold, and still more from the ulterior depression of the tem- perature, in the manner we have seen when speaking of hybernating animals. This dimi- nution in the temperature of the air sometimes occasions among weakly subjects morbid re- action, the principal features of which have already been explained. From all that pre- cedes, the constitutions that will be the most apt to suffer from exposure to cold will be those of the earliest times of life observed in man and the warm blooded tribes generally, since it is at this epoch that they produce the least heat; and as a corollary from this, we should infer that the mortality in early life ought to be greater during the winter season in this and other countries similarly circumstanced. It became a matter of peculiar interest to verify this inference from the experiments and reasonings of which we have just rendered an account. Messrs. Villerme and Milne Edwards accordingly undertook the necessary inquiries, entering upon extensive statistical researches with reference to the mortality of children in the different seasons of the year in France, and found that the mortality of infants from their birth to the age of three months was generally the greatest in those departments of which the winters were the most severe. For a similar reason, the natives of very warm climates who visit countries whose winters are excessively cold, run great risks of not being able to pro- duce heat enough to compensate the loss they sustain from exposure to the low atmospheric changes, and thus of becoming obnoxious to disease and death in consequence. Those that have elasticity enough of c6nstitution to meet this unwonted demand upon their calorific powers, experience an increase in the energy of the functions upon which the production of heat depends, by which they are brought into har- mony with the climate. Others who are less robustly constituted complain loudly of the cold, languish, and finally perish if they do not find means of escaping from the destructive tendency of the cold. What happens, in as far as these different con- stitutions are concerned, when the change of season is the opposite of that we have just dis- cussed ? when the progress is from the colder to the hotter period of the year ? The constitu- ANIMAL HEAT. 679 lions that have just been particularly mentioned, it is obvious, will find themselves benefited by the change ; they are continually supplied with larger proportions of heat of which they were especially in want. But robust constitutions, in which the calorific faculty is largely deve- loped, will they not be in an opposite position, unless the energy of the faculty in question diminishes in proportion as the external tem- perature increases? This in fact is what of necessity happens to those in whom the power of accommodation is defective. For when the calorific faculty continues in full force, when the temperature of the surrounding- atmosphere is high, there is an excess of heat proceeding from within as well as from without ; and if the body does not suffer in the first instance, which it is apt to do, it before long feels the deteriorating influence of this additional excitement, which thensuperinduces a series of morbid phenomena of various degrees of intensity according to circumstances. All this is observed to occur in the most distinct manner among the natives of cold climates who come to reside in very hot countries. The most robust are even observed to be the most apt to suffer from the change, and the effect is so decided, that few escape some derangement of health, occasioned solely by the influence of the high temperature. When the affection appears in the acute form, after recovery, the new comer is said to be seasoned. The constitution appears to have suffered a favour- able change, which consists essentially in a decrease of the faculty to produce heat. In fact it is often only by a process of this kind that the calorific power can be brought into harmony with the new circumstances in which it is placed. Something of the same kind even takes place in the constitutions of the inhabitants of the countries which have two very different temperatures during the two halves of the year. Here, however, the change of constitution ge- nerally passes insensibly or nearly so, the transition being both less in itself, and the natives being accustomed to the difference. Let us just remark that we have here another instance of the vis medkutriv natura, the ten- dency of which at all events is salutary, but of which the violence of effect by exceeding the proper limit frequently becomes fatal. We even perceive here that nature has two pro- cesses at her command, by which she adapts us to changes of external circumstances ; the one is gradual and insensible, the other is sudden and violent. From repeated observation, and from experi- ments upon the effects of exposure to high tem- peratures, it is easy to infer the general charac- ter of the disease in its simplest form, which the natives of cold climates will be likely to con- tract in hot countries. As a high temperature of the air accelerates the breathing and excites the circulation, it may arouse these functions to such a pitch, that the condition becomes truly pathological, and the disease which results is continued fever with excessive heat of surface in those countries where the external conditions are subject to little variety. There are other phenomena accompanying changes of climate that are referable rather to the state of health than to any morbid condition that bears upon the sensations. It is a general re- mark that natives of the warmer regions of the earth, of a good natural constitution, when they visit countries within the temperate zone, suffer little from the effects of cold the first winter ; on the contrary, they seem to live very much at their ease, except in extreme cases. Let us see if we can explain this fact with the assistance of the principles established above. If the natives of warmer climates come during the summer to temperate countries, they experience a change of no great amount indeed, and which, in the generality of cases, is not obvious. The heat grows less and less intense, declining gradually ; freshness or coolness succeeds ; then comes moderate, and at last severe cold. Well- constituted individuals, therefore, and they may be assumed as the majority, will experi- ence the general influence of a gradual cooling process; that is to say, their faculty of produ- cing heat will increase, whence will result a feeling of warmth and of comfort. But this faculty has its limits of increase, which in fact lie within narrower bounds than in the case of well-constituted natives of temperate climates. They are consequently apt at length to fall short of the mark, and so to remain, in regard to calorification, under the standard necessary to the economy. Whenever the progression of which we have spoken ceases, which hap- pens in the course of the second winter, these individuals begin to experience tiie uneasiness which results from its deficiency. It is easy to confirm and render manifest the justice of the above deduction by means of a simple yet curious experiment. If a person having warm hands will keep one plunged for some time in water near the freezing point, it becomes chilled of course, but reaction will be observed soon to take place, and the hand will become red. If it be now taken out of the water and wiped dry, the individual being all the while in a cool at- mosphere, at 10° or 12° c, the hand will by-and- by begin to glow, and the feeling in it will be that of a temperature considerably above the heat of the other hand ; — judging by the feeling alone the hand seems hotter than the other; tried by the thermometer, however, it will be found, to be cooler; or if it be applied to the other, it will at once be discovered to be below the tem- perature of the hand that was not chilled. Let us follow the effects upon common sen- sation produced by a change of climate of an opposite kind. When the inhabitants of cold countries visit the hotter regions of the globe, how do they contrive to endure the heat in the first instance? Experience has often shown that when they are of the same race, they endure it at first with even greater ease than the natives themselves, and that they brave with greater hardihood and less suffering the utmost ardour of the sun. This capacity of resistance, how- ever, has its term, and those who possess it 680 ANIMAL HEAT. gradually lose it, as has been shown in a former passage of this article. The native of the colder clime is more robust, and his nervous system, less impressible, resists painful sensa- tions in a greater degree, and is not over- whelmed by the first effects of noxious influ- ences. This conclusion is also susceptible of demonstration by the way of direct experiment. If during summer a frog be completely im- mersed in a small quantity of water at the ordi- nary temperature of this season of the year, and the same experiment be repeated during winter with water heated to the summer pitch, the animal will live much longer in the latter than in the former instance. The nervous sys- tem of the animal, by the continued action of the cold of the autumn and winter, has been rendered much more capable of resisting noxi- ous influences, as we have had occasion to see already. It is on the same principle that the Finlander, according to the account of Acerbi, can endure a bath at a much higher tempera- ture than it could be borne by a native of a warm or more temperate climate. EFFECTS OF VARIOUS OTHER CAUSES OF MODI- FICATION IN EXTERNAL AGENTS. The effects of external heat and cold on the sensations and on the system in general are not altogether dependent on degrees of temperature. Even at the same degree atmospheric effects are often very different, being principally influ- enced by the state of dryness or moisture, and by that of motion or rest, of the air. Speaking generally, media exert modifying influences other than those comprised in their tempera- ture upon the phenomena of animal heat. Eva- poration is a powerful cause of cooling, which increases in the same measure as the evapora- tion. In the summer season, consequently, during a state of the weather in which the temperature is the same, but the hygrome- tric condition different, the heat of the body will be higher in moist than in dry air. In the same way we observe all the effects of excessive temperature upon the body to be much more intense with a moist than with a dry atmo- sphere. Intheclimate of northern France orEng- land it would be impossible to stand a vapour- bath at a temperature between 40° and 50° c. (104° to 122° F.) for more than ten or twelve minutes ; but with a perfectly dry state of the air it is possible to bear a temperature twice, or more than twice as high during the same space of time. M. Delaroche found that he could not remain in a vapour-bath raised in the course of eight minutes from 37°,5 to 5 1°,25 c. (100° to 125° F.) for more than ten minutes and a half, although the bath fell one degree. M. Berger was compelled to make his escape within twelve minutes and a half from a vapour- bath the temperature of which had risen ra- pidly from 4 1°,25 to 53°,75c. (106°tol29°F.). Both of these experimenters felt themselves become weak and unstable on their legs, and were affected with vertigo, thirst, &c. The weakness and thirst continued through the remainder of the day. But in the course of Dr. Dobson's experiments, a young man con- tinued for twenty minutes in a dry-air stove, the temperature of which was 98°,88 c. (210° F.), within a degree or two, conse- quently, of the ordinary boiling temperature of water. His pulse, which usually beat 75 times in a minute, now beat 164 times. This, however, is by no means the degree of heat that can be and that has been en- dured. M. Berger for five minutes bore a temperature of 109°,48c; and Sir Charles Blagden went still further, having exposed his body during eight minutes to the contact of dry air heated up to the extraordinary pitch of 115°,55 and 127°,7c. (240° and 260° F.). In assigning 40° or 50° c. (104° or 122° F.) for the limits of moist temperature that can be borne by the inhabitants of these coun- tries, we are perfectly aware that in other lati- tudes it can be greatly exceeded. Thus Acerbi, in his journey to the North Cape, informs us that the Finnish peasantry remain for half an hour or more in a vapour-bath, the temperature of which finally rises to 70° and even 75° c. (158° and 167° F.). We have already given the reason of this difference of constitution. Experimental philosophers have not yet tried the precise comparative cooling effects of dry air and of watery vapour ; but all are agreed that the powers of the moist atmosphere are by far the most considerable. To measure the comparative effects upon the economy the fol- lowing experiments were instituted. In equal spaces, the one filled with air at the point of extreme humidity, the other with extremely dry air, were placed young birds of the same age, which were as yet incapable of maintaining their temperature at its proper height when taken out of the nest. It was found that they lost temperature nearly in the same propor- tion in the same space of time when the air was either at the point of extreme humidity or of great dryness. Therefore moist air tends to cool at least as much as dry air by evapora- tion. It cools both by the abstraction of heat and by its action on the nervous system. Its action on the nervous system is of a debilitating nature, and therefore tends to diminish the power of generating heat. The sensation of cold was evidently greater in the moist air, as was shown by the shivering of the animal. There can be no doubt that the action of vapour in this case is complicated by a physi- cal influence in the one instance, and by a pecu- liar physiological effect on the nervous system in the other ; for it is well ascertained that water, as contrasted with air, has a debilitating effect upon the economy. General experience comes in support of these results ; men have ever agreed that moist and cold states of the atmo- sphere and humid and cold climates were more difficult to be borne than those of an opposite character. Such climes in fact are in them- selves extremely insalubrious. By their pecu- liar effects on the economy they tend greatly to lessen the power of producing heat, and they also engender intermittent fevers, among other morbid conditions. According to the state of ANIMAL HEAT. 681 the economy and the degree of the external temperature, watery vapour tends to refrigerate still more in winter, and to add to the heat in summer. The state of the atmosphere in regard to motion or rest modifies to a great extent the effects of a given temperature upon the body. Refrigeration by simple contact increases in amount with the rate of motion of the air. The same law holds good in regard to evaporation, and indeed this process always complicates the results proceeding from simple contact. The cause of refrigeration in this case is consequently double. It is easy, therefore, to imagine how powerful a cause of cooling a cold wind must be. But observation can alone give any ade- quate idea of the extent of its influence in this respect. Mr. Fisher, one of the surgeons in the expedition under the command of Sir Edward Parry to the Polar Seas, has given us an account of its extraordinary effects. In the frozen regions around the arctic circle, the hardy voyagers under Capt. Sir E. Parry found that they could stand a cold adequate to freeze mercury when the air was perfectly calm, much more easily than a temperature nearly 50° F. higher when it blew. The air in motion in this case, therefore, produced a sensation of cold that was equal to such a depression of temperature as is indicated by a fall of 50° of the scale of F. — a most prodigious difference. Sudden transitions of temperature also exert a great influence independently of any limits ; in the first place, because the intenseness of the sensation of cold or of heat is in propor- tion to the suddenness of the abstraction, or of the communication of heat ; and again, be- cause the faculty of adaptation to different degrees of external temperature is not acquired all at once, but is only attained in a certain lapse of time, and by gradual modifications in the constitution. We therefore see that those countries of which the temperature is very high in the day, but very low in the night, are subject to diseases that seem to belong more peculiarly to cold and moist latitudes, or to marshy lands where malaria prevails. But the transition from hot to cold is not limited to the suddenness of the thermal de- pression ; it extends to the refrigeration by the action of the wind. This is another among the many reasons why in the latitudes of Eng- land, France, &c. spring is a more dangerous season than autumn. There are, however, cer- tain cases of sudden transition that are useful and salutary, as forinstance,when the heat of the body is excessive, and is doing mischief, whe- ther it be induced by an elevated external temperature, or proceeds from the violent and involuntary action of our organs. Then re- frigeration even of the most sudden kind, pro- vided it be restrained within proper limits, becomes beneficial. It is thus that the affusion of cold water produces such excellent effects in cases of extreme excitement, and where the temperature is really above the natural standard. This process is even to be regarded as one of the most brilliant tri- umphs of modern medicine. It is much to be regretted that recourse is not had to it more frequently. It is evident that the proper time for the use of this powerful means is that in which congestion has not yet passed into ob- stinate engorgement, that is to say, in the beginning of the disease, in which by allaying excitement congestion is diminished. The favourable moment for using the cold affusion is that in which the skm is hot and dry, which is also the period of the highest excitation. The experiments upon the effects of baths, quoted above, tend also to show the propriety of the practice ; in citing these, we mentioned that the diminution of temperature produced in the body lasted for hours, and that the reaction consequent upon the use of the bath did not carry the temperature higher than the pitch it possessed at starting. It is obvious that the effects of the cold affusion are to be derived from the principles previously established ; since we have referred the production of heat to two general conditions of the economy, one of which is the state of the nervous sys- tem. Now the affusion of cold water acts directly upon this system. There is another powerful method of tempering animal heat, which flows from the other general condition, upon which the production of heat depends, viz. the state of the blood. We have seen above that the respective proportions of the serous mass of the blood and of its red glo- bules exert an important influence; that in the class of vertebrate animals which produce smaller quantities of heat, the proportion of the serum was in the inverse ratio of the faculty of calorification. Whence it follows, that in cases of excessive heat of body, to reduce the quantity of red globules would prove an effectual mode of reducing the tem- perature. Now this is precisely what is done by bloodletting. The effect, however, in this way is not instantaneous. The first influence of bloodletting is simply to lessen the quan- tity of the blood, and this is the extent to which ideas of the influence of the abstraction of blood are generally confined. There is, however, a consecutive influence, which is at the least as important, and which proves much more lasting. As the person who has been let blood confines himself at the same time to low diet, and principally to liquids, it is obvious that the blood is recruited in its quantity principally by additions of watery particles, without any notable or even sensible addition of globules. The blood is therefore altered essentially in its constitution; the proportion of its component fluid and solid elements is changed, and this in direct proportion to the extent and frequency of the venesections. The consequence of this is a diminution of tempe- rature, unless other causes oppose such an ef- fect. Bloodletting, it must be observed, is not the sole means of accomplishing such a change in the constitution of the blood. We can pro- duce a similar effect by exciting one or all of the secretions which are thrown off by the body. Secretion is performed at the cost of the blood, which supplies both of its element? 682 ANIMAL HEAT. — the solid and the fluid part. The more the secretion eliminated abounds in solid parts or matters formed at the cost of the solid constituents of the blood, the more is the blood impoverished in these elements — the more is its mass of globules diminished. Absorption then begins, as in the preceding case, to make up the quantity of circulating fluid ; and if this faculty have only fluids to work upon, it is evident that, as in the case of bloodletting, the blood will become more serous than before. The perspiration and the alvine secretions act in this manner, and nature makes use of these, especially of the former, to temper the burning heat of paroxysms of fever. Art but imitates nature in the treat- ment of acute diseases ; she strives to procure action of the skin, and especially action of the bowels. The use of diaphoretics and pur- gatives is therefore plainly borne out by the principles which have been laid down. The alvine secretions are those especially that carry off the largest proportion of solid matters from the blood, and which therefore, when excited, prove the most permanently efficient in keep- ing down the temperature of the body. There is another important reason for preferring the intestinal canal to the skin as the means, in the generality of instances, of reducing tem- perature in the treatment of disease, which ought not to be lost sight of : this is, that we can excite the intestinal evacuations to a great extent without arousing the circulating system in almost any degree ; very different from what occurs when we attempt to unload the vessels by the way of the cutaneous exha- lants, in which it is generally impossible to produce abundant diaphoresis without arous- ing the heart and arteries to unwonted action as a preliminary. Purgative medicines, there- fore, next to the direct abstraction of blood, are the most potent means of tempering the heat of the body by modifying the consti- tution of the blood. Nothing that influences the economy can have an effect in one direc- tion only. It were foreign to our purpose, however, to enter upon any other than that which bears immediately upon our subject. There is another natural process analogous in its effects, which the preceding consider- ations place in a new point of view. This is the influence of diet and regimen. Low diet does not act merely in preventing the ex- citement which always follows the ingestion of solid food ; it further alters the constitution of the blood. This fluid, receiving a more scanty supply of solid matters, continues nevertheless to supply the natural secretions as before, and consequently very speedily undergoes by this alone a diminution in the proportion of its globules, in the direct ratio of the duration of the system of spare diet. Low diet is there- fore a means which acts in the same way as bloodletting and purging, with this difference however, that it is slower in its operation, and in the first instance less marked in its effects. This, therefore, is the slowest and least efficaci- ous of the immediate means of reducing tem- perature when employed alone, although its conjunction is indispensable to the success of any of the others. Of all these means, one only is the proper effect of art, namely, the application of cold ; the others are processes of the same natura medicatriv, and processes which we merely imitate. These act directly in modifying the constitution of the blood, and thus definitively influence the nervous system. The other exerts its influence directly on the nervous system, in calming the excitement or violent action which it has engendered in the sangui- ferous system, and those that depend on it. The application of heat becomes necessary in morbid states the reverse of those that have just been discussed. The proper employ- ment of this means depends especially on two general principles bearing upon animal heat, which we have considered above. 1st, The one is, that the economy has the capacity of bearing heat in the same proportion as the function of respiration is extended. In those cases in which this function is limited, or, what comes to the same thing, where any part that requires an accession of heat is indiffer- ently supplied with arterial blood, it is neces- sary to be extremely cautious in its applica- tion. 2nd, The other, that the effects of ex- ternal heat are not confined to the simple interval during which it is applied, but remain after it has been removed, and even increase the faculty of producing heat. The applica- tion of warmth is therefore not merely pallia- tive or supplementary of lost heat ; it has further a directly remedial influence, which may even be excited in excess. When the lesion of the calorific faculty has been great, without much or any organic lesion, other means of greater force than those usually re- sorted to by art, or employed by nature in such circumstances, must be called in to assist. Art has happily discovered what seems the most effectual means of winding up the nervous system, and enabling the calorific faculty to be re-established in its normal con- dition. This means is quinia, the first of tonics. This powerful medicine is conse- quently never administered in acute diseases until all violence of action has ceased, and the functions have resumed their habitual rythm. We find that the action of this medicine is exerted directly upon the nervous system from this, that it seems to have no effect on the secretions, or when it does in- fluence these, we are convinced by the tri- fling amount of the effect, that it is not through them that the cure is accomplished. As it acts during the intermission, by restoring the normal production of heat, we have no reason to expect the phenomena which characterize the fit — the shivering, &c. ; and then the vio- lent reaction which we have in the hot stage becomes useless, and in fact is no longer ob- served. Confirmation of the general results. We have thus passed in review the principal phenomena of animal heat, reducing or ap- proximating these at all times to the most ANIMAL HEAT. 683 simple conditions. These conditions them- selves are, in the first place, assumed from comparisons of the organization of the two grand groups or series into which the animal kingdom is divided with reference to heat— the cold-blooded animals, and the warm- blooded animals. In this review we have avoided all hypothesis, confining ourselves to the severe method of deduction, always starting from well-authenticated facts, and even con- firming each step in advance by new data equally indisputable. The harmony which reigns in this comprehensive whole, which embraces the different classes of animals and man, not only in the various modifications of health, but even of disease, in their relation to external agents, and the therapeutic pro- cesses of nature and of art, afford the surest confirmation of the reality of these relations. As the phenomena of animal heat are re- ferable to two general conditions of the eco- nomy,— the state of the blood and that of the nervous system ; and as we have only in the first instance deduced these from the com- parison of natural facts, although we have confirmed them by new observations and par- ticular experiments, one may be desirous of seeing them confirmed by experiments of a more general bearing. To the reasonableness of this wish we yield assent the more willingly, as the results we have to quote are deductions from some of the most admirable researches that have been instituted by physiologists ; — I allude to the enquiries of Legallois, Sir Benjamin Brodie, and Dr. Chossat. The first of these experimenters, by the em- ployment of various means for impeding re- spiration, or limiting the consumption of air, found that the refrigeration of animals is in the compound ratio of the difficulty experienced in breathing and of the quantity of oxygen con- sumed ; so that when, in two experiments, the difficulty of breathing is the same, the greatest extent of cooling occurs in that in which the smallest quantity of oxygen is vitiated, and the contrary. Now, the end of the process of respiration being to change the venous into arterial blood, this conclusion of Legallois con- firms directly the one of the two principal conditions — the state of the blood, which we have laid down as influencing the production of heat among animals, and to the knowledge of which we had attained by induction. The results of the direct experiments which we have still to quote also come powerfully in aid of our inferences concerning the other principal condition, which we have assumed from induction, influencing the production of animal heat: this is the state or action of THE NERVOUS SYSTEM. Sir B. Brodie demonstrated by a series of the most ingeniously conceived and happily executed experiments, that when animals were decapitated and respiration was kept up by artificial means, so that the blood circulated as usual, and the process of change from the venous to the arterial state went on uninter- ruptedly, the ordinary quantity of carbonic acid being eliminated, all the while, that, ne- vertheless, the temperature fell rapidly, even more rapidly than when no artificial respiration was maintained. Dr. Chossat completed these researches upon the nervous system in its relations with the production of heat, by demonstrating in a series of experiments the following very im- portant fact, viz. that the depression of animal heat is constantly in relation with lesions of the nervous system, whether these lesions im- plicate the cerebrospinal system, or the system of the great sympathetic. We necessarily confine ourselves, in alluding to these admirable researches, to the most general results, and the conclusions flowing most immediately from the experiments insti- tuted. We reserve a more particular mention of them for the proper place, namely, the article on Respiration, to which we beg to refer. With regard to the opinions of writers generally, we shall be content to observe here, that they have for the most part regarded the single physiological condition which was the subject of their particular study as the only source of animal heat. The general result of their united labours, however, is, that there are two principal sources, the one depending on the arterial blood, the other on the energy of the nervous system, — a conclusion to which we have come by another way, by combining all the known facts that bear upon animal heat, and embracing the manifestations presented by the whole of the animal kingdom as well as the isolated phenomena exhibited by man, and this not in one but in every condition of ex- istence, not only in the state of health but of disease likewise, not as beings independent of all things around them, but as living in intimate relationship with external agents. Of the physical cause of animal heat, With regard to the physical cause of animal heat, or to its mode of production, there was a time, which we have not yet left very far behind us, when natural philosophers and chemists imagined they possessed the secret, especially with reference to the mineral king- dom. They have now discovered their mis- take ; and as the evolution of heat is a mystery to them, it is not to be expected that it is less so to physiologists, as manifested in the do- main which they cultivate in peculiar. The problem, in fact, becomes immensely com- plicated by a variety of phenomena when from the inorganic we ascend to the organic world. All that could be done has been accomplished ; from the particular conditions of organization and of function upon which this effect seemed to depend, physiologists have risen to those that were the most general and com- prehensive. This, in fact, was the end we proposed in commencing this article. That nothing may be omitted which can make the sketch more complete, and none of the great inquiries which have had animal heat for their object may be passed over in silence, we shall briefly cite the more important of those in which the mode of production of animal heat is discussed, always reserving to ourselves the 684 HERMAPHRODITISM. opportunity of treating several of these more fully in our article on Respiration. Lavoisier, from his labours on combustion, which laid the foundation of the chemical doctrines of the age that has just elapsed, conceived the ingenious idea of explaining the phenomena of animal heat by the combustion of the carbon and hydrogen of the blood by the oxygen of the air in the process of respi- ration, and the experiments which he instituted upon this point along with the illustrious La Place appeared to confirm his idea. Still it was found impossible to give an account of the production of the whole heat engendered by animals. All that Lavoisier and La Place in- ferred was, that the heat evolved by an animal was almost entirely produced by the combus- tion which occurs in respiration. As the calo- rific power was measured in one animal, and the consumption of oxygen in another, it is evident that the inference, vitiated in its ele- ments, became much less precise than it would otherwise have been. This consideration as well as others induced M. Dulong, who is as well versed in mecha- nical philosophy as in chemistry, to take up this subject again. After numerous experi- ments, conducted with every precaution that could secure accuracy of result, he found that the heat disengaged by the fixation of the oxygen in the act of respiration was not equal to the whole of that which was produced by an animal. This inquiry (which however stood in no need of confirmation) has been con- firmed by the analogous inquiries of M. De- spretz, who arrived at the same numerical results. The hypothesis in question, there- fore, gives no solution of the problem. BIBLIOGRAPHY. — Martine, Essay on the genera- tion of Animal Heat, in Essays Med. and Philos. Lond. 1740. Huller, De generat. caloris, &c. Goett. 1741. Stevenson, Essay on the cause of Animal Heat.&c. Med. Essays and Obs. vol. 5. Mortimer, Letter concerning the Nat. Heat of Animals, Phil. Trans. 1745. Braim, De calore animalium, Nov. Comm. Petrop. t. 13. Duncan, Hypotheses of the cause of Animal Heat, Med. and Phil. Com. vol. 6. Experts. &c. Min. of Society for Philos. Ex- perts, p. 157. Martin ( A.R.), Various Papers on Animal Heat in the Svenska Vetensk. Akad. Hand- lingar for the years 1764 and 1766. Hunter, Ex- perts, on the power of producing Heat, and on the Heat of Vegetables and Animals, Phil. Trans. 1775- 1778, and in Animal Economy. Crawford( D.J. M.J, De Calore Animali, Edinb. Exprts. and Obs. on Animal Heat, Phil. Trans. 1786, separately, 2d ed. 1788. Leslie, Philos. Inquiry into Animal Heat, Lond. 1778. Rigby, Essay on the Theory of the Prod, of Animal Heat, Lond. 1785. Delaroche et Berger, Mcmoire, &c. in Journ. de Physique, t. 71. Brodie, in Croonian Lecture, Phil. Trans. 1811. Davy, An Acc. of some Experts, on Animal Heat, Phil. Trans. 1814. ' Legallois, Mem. sur la chaleur animale, Ann. de Chimie, t. iv. Earle, Influence of the nervous system in regulating Heat, Med. Chir. Trans, vol. vii. Chossat, Influence du Systeme Nerveux sur la Chaleur Animale, These, Paris, 1820. Dulong, De la Chaleur Animale, Journ. de Physiol, t. 3. Despretx ( Rich.), Exper. sur la Chaleur Anim. Ann. de Chimie, t. 26. Home, Influence of the Nerves in prodticing Animal Heat, Phil. Trans, v. 115. Collard de Martigny,De l'Influence de la Cir- culation, &c. sur la Chaleur du Sang, Journ. Com- plem. t. xliii. Vide also Journ, Complem. t. xxvi. The general works on Physiology, particularly those of Rudolphi and Tiedemann. Czermack, On the Temperature of Reptiles, in Zeitschr. fiir Phy- sik, &c. Bd.3. Berthold, Neue versuche uber die Temperature, &c. Gotting. 1835. Transl. in Ann. d'Analomie, &c. Mai 1838. Newport, Temp, of Insects, Phil. Trans. 1837. Becquerel Breschet, Mem. surla Chaleur Animale, in Ann. des Sciences, Nat. Seconde Serie, t. 3, 4, & 9. ( W. F. Edivards.) HERMAPHRODITISM, or Hermaphro- dism;* Hermaphrodisia ; androgynisme, gynan- drisme ; hermaphroditisme, &c, of the French ; ermaphrodismo of the Italians ; Zwitterbildung of the Germans, &c. Many different definitions of hermaphro- ditism, and almost an equal number of diffe- rent classifications of the malformations usu- ally comprehended under it, have been proposed by the various authors, ancient and modern, who have directed their attention to this sub- ject. Without stopping to discuss the merits or errors of these definitions and classifications, and without inquiring, as some have done, into the propriety of the word itself, we shall content ourselves with stating that under it, as a convenient generic term, we purpose in the present article to include an account — 1st, of some varieties of malformation in which the genital organs and general sexual configura- tion of one sex approach, from imperfect or ab- normal developement, to those of the opposite ; and 2d, of other varieties of malformation, in which there actually coexist upon the body of the same individual more or fewer of the geni- tal organs and distinctive sexual characters both of the male and female. To separate from one another, by as strong a line as possible, the two distinct varieties of hermaphroditic malformation marked out in this definition, we shall divide hermaphroditic malformations, considered as a class, into the two orders of Spurious and True; the spurious comprehending such malformations of the genital organs of one sex as make these organs approximate in appearance and form to those of the opposite sexual type ; and the order, again, of true hermaphroditism including under it all cases in which there is an actual mixture or blending together, upon the same individual, of more or fewer of both the male and female organs. Spurious hermaphroditism may occur either in the male or female ; that is, there may, from malformation of the external sexual organ, be an appearance of hermaphroditism in persons actually of the female sex, or from a similar cause there may be an appearance of herma- phroditism in persons actually of the male sex. The differences derived from the diversity of sex in which spurious hermaphroditism occurs, and the particular varieties of malformation in each sex which may give rise to it, will serve as * From the well-known mythological fable of the union into one, of the bodies of Hermaphro. ditos (the son of Epftns, Mercury, and A^foJiri, Venus,') and the nymph Salmacis. See Ovid's Me- tamorphoses, lib. iv. lab. 8. HERMAPHRODITISM. 685 bases on which we shall found some further subdivisions of this order. True hermaphroditism, as above defined, comprehends also, as shall be afterwards more particularly shewn, several very distinct varieties of malformation. If we conceive for a mo- ment all the reproductive organs to be placed on a vertical plane, (as we may suppose them to be, though not with strict correctness, in the human body when in the erect posture,) we shall find that the principal of these varieties may be all referred to three sets of cases : — ■ 1st, those in which, if we drew a vertical median line through this supposed plane, the two lateral halves will be seen to present organs differing in this respect, that they belong to opposite sexual types ; -2d, others in which, if we bisect the same plane by a transverse horizontal line, there exist organs of a different sex in the upper from what are present in the lower segment ; or, in other words, the internal genital organs belong to one sex, and the ex- ternal to another. In the two preceding classes of cases there is not necessarily, as we shall afterwards more fully point out, any malforma- tion by duplicity in the sexual apparatus of the malformed individual ; there is only one set of sexual organs present, but in some parts these organs are formed upon the male, and in others upon the female type. In the 3d and re- maining set of cases, however, there is really present to a greater or less, though most gene- rally only to a very partial extent, a double set of sexual organs, having opposite sexual cha- racters, so that upon the same body, and usu- ally upon the same side, or upon the same vertical line in our supposed plane, we find coexisting two or more of the analogous organs of the two sexes. In accordance with this view, we shall consider the cases of true her- maphroditic malformation under the three corresponding divisions of, 1st, lateral; 2d, transverse ; and 3d, vertical, or, more properly, double or complex hermaphroditism ; and each of these genera will admit of some further convenient subdivisions. But the mode in which we propose to classify and consider the subject will probably be at once more accurately gathered from the following table, than from any more lengthened remarks upon it in the present place. Classification of hermaphroditic malformations. r From excessive development of the clitoris, fin the Female < &c. C From prolapsus of the uterus. 'Spurious \_\n the Male. Hermaphroditism "Latei True al. S From extroversion of the urinary bladder. From adhesion of the penis to the scrotum. . From hypospadic fissure of the urethra, &c. Testis on the right, and ovary on the left side. Testis on the left, and ovary on the right side. Transverse Vertical or Double . , In commenting upon and illustrating the different varieties of hermaphroditism in the particular order in which they are placed in the above table, we shall, we believe, by following that order, be able to take a graduated, and, at the same time, a correct and comprehensive view of the subject, beginning with the more simple, and ending with the more complex and complete species of hermaphroditic malforma- tion, as seen in the primary sexual characters, or the structure of the genital parts themselves. We shall then consider at some length the curious and important physiological subject of hermaphroditism as manifested in the secondary sexual characters of the system. After having done so, we shall endeavour to show how far $ External sexual organs female, internal male. \ External sexual organs male, internal female. -Ovaries and an imperfect uterus with male vesicula; seminales, and rudiments of vasa deferentia. j Testicles, vasa deferentia, and vesicula} se- minales, with an imperfect female uterus and its appendages. Ovaries and testicles coexisting on one or botli sides, &c. the diversified forms of hermaphroditic malfor- mation can be explained upon our present knowledge of the laws of developement ; point out the actual anatomical and physiological degree of sexual duplicity which is liable to occur, and the numerous fallacies with which the determination of this question in individual cases is surrounded ; and lastly, in conclu- sion, we shall offer some general observations upon the causes, &c, of this class of abnor- mal formations. I. SPURIOUS HERMAPHRODITISM. A. In the female. — There aretwo circumstances in the conformation of the genital organs of the female, the existence of each of which has oc- 686 HERMAPHRODITISM. casionally given rise to doubts and errors with regard to the true sex of the individual on whom they were found— namely, 1st, a pre- ternaturally large size of the clitoris ; and 2d, a prolapsus of the uterus; the enlarged cli- toris in the one case, and the protruded ute- rus in the other, having been repeatedly mis- taken for the male penis. 1. Abnormal developement or magnitude of the clitoris. — In the earlier months of intra- uterine life, the clitoris of the human female is nearly, if not altogether, equal in size to the penis of the male foetus ; and at birth it is still relatively of very considerable dimensions. From that period, however, it ceases to grow in an equal ratio with the other external genital parts, so that at puberty it is, as a general law, found not to exceed six or eight lines in length. But in some exceptional instances the cli- toris is observed to retain up to adult age more or less of that greater pro- portionate degree of developement which it presented in the embryo of the third and fourth month, thus exhibiting in a per- sistent form the transitory type of structure belonging to the earlier stages of foetal life. In some instances where this occurs, the re- semblance of the external female to the exter- nal male parts is occasionally considerably in- creased by the apparent absence of the nymphae. Osiander* endeavoured to show that at the third or fourth month of foetal life the nymphaa are very imperfect, and so very small as not to be easily observed. Meckel,f however, has pointed out that these organs are not in reality of a small size at that time, but they are liable to escape observation from the folds of skin of which they consist, making, at the period alluded to, a perfectly continuous membrane with the prepuce of the clitoris, and forming indeed, in their origin, only one common mass with this latter body. When the ulterior changes, therefore, which these parts ought to undergo in the natural course of developement in the latter stages of foetal existence, are sus- pended or arrested from about the end of the third month, there may not only coexist with the enlarged clitoris an apparent want of nym- phs, but the resemblance of the female to the male parts may be still further increased by the persistence of the original intimate connexion of the nymphse with the prepuce and body of the clitoris, and by the consequently continuous coating of integuments, as well as the greater size and firmness of this organ. Excessive size of the clitoris would seem to be much less common among the natives of cold and temperate than among those of warm countries. The frequency of it in the climate of Arabia may be surmised from the fact of directions having been left by Albucasis and other surgeons of that country for the amputa- tion of the organ; an operation which iEtius and Paulus Eginetus describe as practised among the Egyptians. According to the more * Abhandlungen iiber die Scheidenklappe, in Denkwurdigkeiten fiir die Heilkunde, Bd. ii. p. 4-6. t Manuel d'Anat. Gen. torn. iii. p. 666. modern observations of Niebuhr* and Son- nini,f circumcision would seem to be still practised upon the females of that country. This variety of conformation of the female parts appears to have been well known to the ancient Greeks, and several of their authors have mentioned the women so constituted under the names of -rp|3a<5£; and E-raif la-T/nai, a class in which the celebrated poetess Sappho (mascula Sappho ) is well known to have been included. Martial, Tertullian, and other Ro- man authors have noticed the same malforma- tion, (fricalrices, confricatrices,) and alluded to the depravity to which it led.J * Beschreibung von Arabien, s. 77. t Voyage dans la Haute et Basse Egypte, torn. ii. p. 37. X Mart. Epigr. lib. i. ep. 91. ; see also lib. viii. ep. 66. The frequency of this crime in the ancient gentile world may be inferred from the pointed manner in which the Apostle Paul alludes to it, Romans, chap. i. 26. In Greece it was in some places forbidden by law, and in others, as in Crete, tolerated by the state. Seneca, in his 95th ep., when speaking of the depravity of the women of his own age, remarks, " non mutata fcemina- rum natura, sed vita est. . . . Libidine vero, nec maribus quidem cedunt pati natae. Dii illas deaeque male perdant, adeo perversum commentae genus impudicitiae viros ineunt." Op. Om. Genev. 1665, p. 787. Clemens Alexandrinus, in his Paedagogus, exposes the same vice : " et contra naturam fremi- nae, viros agunt (avSpif ovrai) et nubunt et etenim uxores ducunt." Also Athenasus, Deipnosoph. lib. xiii. p. 605. Justin Martyr, in his Second Apology, makes a still broader accusation. This author lived in the second century, and in declaim- ing against the vices of that licentious age, he alleges that multitudes of boys, females, and her- maphrodites (androqyni ambigui sexus ) " nefandi piaculi gratia per nationem omnem prostant." Op. Om. Col. 1686, p. 70. See also Marcus Antoni- nus, De Seipso, ed. Gatakeri, Cambr. 1652, lib. iii., note at the end by Gataker. On the extent, among the ancients, of the vices above alluded to, see Meiner's Geschichte des Verfalls der Sitten und der Staatsverfassung der Roemer, Leipzig, 1791 ; Neander's Denkwurdigkeiten, Bd. i. s. 143; Pro- fessor Tholuck's, of Halle, Exposition of St. Paul's Epistle to the Romans, in the Edinburgh Biblical Cabinet, vol. v. p. 102, and in an Essay on the licentious vices, &c, of the ancients, translated into Robinson's American Biblical Repository, vol. ii. p. 441. In the essay last referred to, Tholuck incidentally mentions (p. 422,) that the deity Mi- tra (Mithras of the ancient Persians) was herma- phrodite. For our own part we are inclined to believe that many of the idols of the heathenish mythology of Asia could be traced to the deifica- tion of various monstrosities in man and^ quadru- peds. (See the figures of these idols passim in C, Coleman's Mythology of the Hindus, Lond. 1832; and E. Upham's History and Doctrine of Budhism, Lond. 1829.) It perhaps is not unworthy of no- tice that the Jewish Talmudists, taking the Hebrew noun in the Pentateuch answering to man in its individual and not in its collective sense, consi- dered, from Genesis, chap. i. v. 21, that our origi- nal progenitor was hermaphrodite. (See Jus Tal- mud. Cod. Erwin. c. 2 ; Heidegg. Hist. Patriarch, t. i. 128 ; C. Bauhin De Monstrorum Natura, &c, lib. i.e. 24; and Arnaud's Memoire, p. 249.) It is further interesting to remark that Plato, in his Symposion, introduces Aristophanes as holding the same opinion. " The ancient nature," he observes, " of men was not as it now is, but very different; for then he wa3 androgynous both in form and HERMAPHRODITISM. 687 The dimensions which the clitoris occasion- ally presents are such as to render it, in respect of size alone, not unlike the male penis. It is not unfrequently found of two or three inches in length, but sometimes it is seen five and six inches long. Dr. Clark frequently found the organ an inch long, and thick in proportion, among the Ibbo and Mandingo women.* Hallerf and Arnaud I have collected nume- rous instances of preternatural size of the cli- toris. The former author alludes, among others, to two cases in which the organ was stated to have been seven inches in length ; and to an- other, mentioned by Chabart, in which it was alleged to have been twelve inches,- — a size which we can only conceive to have been the result of disease. When the female clitoris is increased greatly in size, it is not wonderful that it should be sometimes mistaken for the male penis, — the female organ in the Mammalia naturally differ- ing from the male only in regard to its smaller dimensions, its not being perforated by the urethra, and its wanting the corpus spongio- sum,— a peculiarity or defect of structure that exists as the natural type of formation in the penis of male reptiles. In the human subject the organs are composed internally of the same kind of erectile tissue, and when we descend in the animal scale, and examine their relations in the males and females of the same species, we find some still more striking analogical peculi- arities of structure. Thus, in several of the Carnivora and Rodentia, as in the lioness, cat, racoon, bear, marmot, &c. the clitoris contains a small bone like that belonging to the penis of the males of the same species ; and amongst the Monotremata and Marsupiata the clitoris of the female, like the penis of the male, is surmounted by a bifid glans. In a species of lemur (Loi'is gracilis or Slenops tardigra- dus ), the clitoris is of a very large size ; and the urethra, as first pointed out by Daubenton,§ name,"("v^p°>"'l"'v *ai El^°C Kai wofwt.) Probably from the licentious purposes alluded to by Justin Martyr, or from the weak and imbecile character of her- maphrodite individuals, the word avSpoyno? came in latter times to signify effeminate and luxurious. The ancient lexicographer Hesychius gives it this meaning ; and Theodoret, in his Therap., speaks of Bacchus as being licentious, effeminate, and an- drogynous— (yuvvic tuv, nai flnXuJpittff, xoi avJpojoivo?. ) * Home's Comp. Anat. vol. iii. p. 317. On the peculiarities of the external genital organs in va- rious African tribes, see a learned paper by Prof. Miiller in his Archiv fuer Anatomic for 1834. Ht. iv. s. 319., with ample references to the observa- tions and opinions of Levaillant, liarrow, Peron, Lesner, Lichtenstein, Burchcll, Somerville, &c. See also Otto, in his Neue Seltenc Bcobaehtungcn zur Anatomie, p. 135, shewing the very prominent external female parts of different African tribes to consist differently, 1 , of enlarged nymphae, 2, of enlarged labia, and 3, of the enlarged clitoris. t El. Phys. torn. vii. part ii. p. 81, 82. X Dissertation sur les Hermaphrodites, p. 372. See also Homberg, De Excrescentia Clitoridis nimia, Jena, 1671 •, Troncliin, De Clitoridc, JLugd. 1736; and Ploucquet's Literatura Mcdica, art. Clitoris Magna, torn. i. p. 299. § Audibert, Histoire Nat. des Singes, tab. ii. fig. 8. runs forward and opens at its anterior extre- mity between the branches of its glans, imita- ting, in this point of structure, the penis of the male among the Mammalia. In the human subject the mere enlargement of the clitoris alone has seldom of itself given rise to errors with regard to the sex of the indi- vidual, except in young children ; but it has frequently happened that along with it other minor malformations have coexisted, so as to render the sexual distinction much more ambi- guous. In women possessing this peculiarity of structure we sometimes observe, for in- stance, the clitoris not only resembling the penis in size, but it has an indentation at the point of the glans, imitating the orifice of the urethra ; and occasionally the glans is actually perforated to a certain extent backwards, or the body of the clitoris is drilled more or less imperfectly with a canal like that of the male urethra. In other instances the canal and orifice of the female vagina are, by an excess of development in the median line of the body, much contracted or nearly shut up, the vulva being closed by a strong membrane or hymen, and the labia cohering so as to give the parts a near resemblance to the united or closed perinffium and scrotum of the male. Further, in one or two very rare cases which have been put upon record, the ovaries and Fallopian tubes seem to have descended through the in- guinal rings into the labia, thus giving an ap- pearance of the presence of testicles ; and a fallacy seems to have occurred in some cases from the presence of roundish masses of fat in this situation simulating more or less the same male organs. Besides, it often happens in those women who present more or fewer of these peculiarities of conformation in the external genital parts, that the general or secondary sexual characters of the female are wanting, or developed in a slighter degree than natural, owing probably to the malformations of the external organs being often combined with some coexisting anomalies in those more important internal re- productive organs, the healthy structure and action of which at the time of puberty appear to exercise so great an influence on the deve- lopment of the peculiar general conformation and moral character of the female. Thus the features are sometimes hard, the figure and gait rather masculine, the mamma? slightly developed, the voice is deep-toned, and the chin and upper lip are occasionally covered with a quantity of hair. In fact, in some marked cases the whole external character ap- proaches to that of the male, or, more pro- perly speaking, occupies a kind of neutral ground between that of the two sexes. Some of the more striking examples of this first va- riety of spurious hermaphroditism in the fe- male will sufficiently illustrate the above re- marks. Dr. Ramsbotham* has briefly described the genital parts of an infant, that was christened and looked upon as a boy, until dissection after * Medical Gazette, xiii. p. 184. 688 HERMAPHRODITISM. death shewed that the sex was actually female. The uterus and other female organs (Jig. 287, c c c) were present and apparently naturally Fig. 287. formed ; but the clitoris (b) was fully as large, and in appearance closely resembled the penis of a male of the same age. At its anterior extremity there was a sulcus («), which was not the entrance of the urethra, but terminated in a cul-de-sac. Columbus* and De Graaff give two similar examples of the same form of spurious her- maphroditism in young children, in which the true sex was only fully ascertained by dis- section after death. In relation to the clitoris in the case described by Columbus, that author states that this organ was furnished with two muscles only, and not with four, as in the per- fect male. In a reputed hermaphrodite woman, Gallay J found after death the clitoris to be three and a half inches long, and three inches and four lines in circumference. The glans and prepuce were well developed. The urethra ran as in man through the body of the penis and its glans. The labia, nympha, vagina, &c. were natural, and the internal female organs, the ovaries, Fallopian tubes, and uterus, are de- scribed as scirrhous. This woman had been married, but never had any children ; her ca- tamenia, however, had been very regular. She had a considerable quantity of hair upon her face, and her voice was harsh and masculine. In a child of two years of age, Schneider,§ on dissection after death, could find neither the labia externa nor interna, nor any trace of the ordinary cleft between them. The clitoris was an inch and a half long, and externally resembled most perfectly a male penis fur- nished with a glans and prepuce ; but it was imperforate, having only at its anterior extre- mity a small spot marking the situation of the opening of the urethra in the male. Some * De Re Anatomica, lib. xv. p. 493. t Op. Om. cap. iii. xv. or, De mulierum organis gen. inserv. with a plate, t Arnaud, 1. c. p. 309. i Jahrbiicher der Staatsarzneikunde, (1809), s. 193. lines below there was an opening by which the urine was evacuated. This opening formed the entrance to the vagina, which was found of the usual length, and with the characteristic rugee. The canal of the urethra was found entering its roof, but in such a manner that the urine was always evacuated very slowly and by drops only from the external opening. All the internal female sexual organs were natural. M. Beclard* has left us a very detailed and interesting description of an example of spu- rious hermaphroditism referable to the present variety, and exhibited at Paris in 1814. The subject of the case, Marie Madeline Lefort, was at that time sixteen years of age. The proportions of the trunk and members, and of the shoulders and pelvis, and the conformation and dimensions of this last part of the body, were all masculine; the volume of the larynx also, and the tone of the voice were those of an adolescent male ; a beard was appearing on the upper lip, chin, and region of the parotids; some hairs were growing in the areola around the nipple ; and the mammas were of a mode- rate size. The inferior extremities were fur- nished with an abundance of long hard hairs. The symphysis pubis was elongated as in man ; the mons veneris rounded, and the labia ex- terna were covered with hair. The clitoris was 10J (?) inches (27 centimetres) in length when at rest, but somewhat more when erect ; its glans was imperforate, and covered in three- fourths of its circumference with a mobile pre- puce. The body of this enlarged clitoris was furnished inferiorly with an imperfect canal, which produced a depression in it, instead of that prominence of this part which exists in the male penis. This canal was pierced along its under surface and median line by five small holes capable of admitting a small stylet ; and one or more similar apertures seemed to exist in it after it reached backwards within the va- gina. The labia were narrow and short, and the vulva or sulcus between them was superfi- cial, being blocked up by a dense membrane, which, under the pressure of the finger, felt as if stretched towards the anus over a cavity. At its anterior part, or below the clitoris, there was an opening capable of admitting a sound of moderate size, and this sound could be made to pass backwards behind the membrane closing the vulva, which, when felt between the point of the instrument and the finger, seemed about twice as thick as the skin. The urine was passed by this opening, and also, according to the report of the individual herself, through the cribriform holes in the canal extending along the inferior surface of the urethra. By the same opening the menstrual fluid escaped, as Beclard ascertained on one occasion by per- sonal examination. She had menstruated re- gularly from the age of eight years, considered herself a female, and preferred the society of men. In this interesting case we have present all the secondary sexual characters of the male, * Bulletins de la Faculte for 1815, p. 273. HERMAPHRODITISM. 689 with some of the female genital organs deve- loped in so excessive a degree as to approach in several points the more perfect structure of them in man. The impossibility, however, as mentioned by Beclard, of finding any bodies like testicles in the labia or in the course of the inguinal canals, and more particularly the well-ascertained fact of the individual menstru- ating, can leave no doubt as to the nature of her sex. The perforation of the enlarged cli- toris with the imperfect urethra is interesting, when compared with the peculiarities that we have formerly alluded to, of this part in the female Loris, as pointing out, what we have so often occasion to observe in human monstrosi- ties, a type of structure assumed by a mal- formed organ similar to the normal type of struc- ture of the same organ, in some of the inferior animals. Arnaud* has represented and described at great length an interesting example of herma- phroditic malformation that seems referable to the head of spurious hermaphroditism in the female, although there are two circumstances in the history of the case which have led some authors to doubt the accuracy of this opinion ; and the opportunity that was afforded of ascer- taining the true structure of the parts after death was unfortunately lost through careless- ness and neglect. The subject of the malfor- mation, aged 35, passed in society for a female, and came to Arnaud complaining of a small tumour (fig. 288, e) in the right groin, which Fig. 288. had incommoded hermuchduring her whole life. On examining this body, Arnaud was led to believe that it was a testicle, and he found a similar tumour (_/') situated nearer the inguinal ring on the left side. The bags that contained them represented very exactly the labia externa. The clitoris (a) was two inches and nine lines in length, and placed between the labia at their upper angle. The glans (b) was well formed, and though imperforate at its extremity, it pre- sented a small depression which ran backwards along the whole inferior border of the clitoris, indicating the situation of a collapsed urethral canal, that seemed pervious for some length at * Dissertation sur les Hermaphrodites, p. 265, pi. x. VOL. II. its posterior part, as it became distended when the patient evacuated the bladder. The ori- fice (c), however, from which the urine actually flowed, occupied the situation in which it exists in the perfectly formed female. There was not any vaginal opening, and the individual men- struated per anum. At each menstrual period a tumour (d) always appeared in the perinaeum, which gradually increased in size, becoming, in the course of three or four days, as large as a small hen's egg. When the perinaeal tumour had reached this size, blood began to flow from the anus, although no haemorrhoids or other disease of the bowel was present. At these periods the individual had often expe- rienced very alarming symptoms, and in order to avert these, Arnaud was induced to make an opening into the soft yielding space at which the perinaeal tumour above alluded to appeared; and at a considerable depth he found a cavity two inches in circumference, and about two and a half in breadth, having projecting into it at one point an eminence which was supposed from its situation to be possibly the os uteri. At the next period the menstrual fluid came entirely by the artificial perinaeal opening, and the usual severe attendant symptoms did not supervene. From inattention, however, to the use of the tent, the opening was allowed to become completely shut, so that at the sixth return of the menses they flowed again by the anus, and were accompanied by the old train of severe symptoms. The individual lived for several years afterwards. Her conformation of body was remarkable. Her skin was rough, thick, and swarthy; she had a soft black beard on her face ; her voice was coarse and mascu- line ; her chest narrow ; her mammas were flat and small ; her arms lean and muscular ; her hands large, and her fingers of very considerable length and strength. The form, in fact, of the upper part of her body was masculine, but in the lower part the female conformation predo- minated. The pelvis was wide and large, the os pubis very elevated, the buttocks large, the thighs and legs round, and the feet small. In this remarkable instance, if we do not go so far as to conceive the coexistence of some of the internal organs of both sexes, we must, from the well-ascertained fact of the menstrual evacuations, allow the person at least to have been a female. In that case we can only sup- pose the tumours in the labia to be the ovaries descended into that situation ; and to the same excess of development which has produced this effect, we may attribute the closure of the vaginal orifice, and the formation of the imper- fect urethral canal in the body of the clitoris. Spurious hermaphroditism from preternatural enlargement of the clitoris has been recognised among some of the lower animals. Rudolphi* has noticed a mare of this kind that had a clitoris so large as almost to shut up the en- trance into the vagina. Lecoqf has detailed * Riulolphi's Bemeikun^en auf einer Reise, &c. Bd. i. s. 79. See a case also figured by Ruysch la his Thesaurus Anat. lib. viii. no. 53. t Jouin. Piat. which, under pressure and irritation of the genital parts, gave out several drops of a transparent mucous fluid. Otto considers these openings as the extremities of the ducts of the prostate and Cowper's glands, and of the semi- nal canals. The right half of the scrotum con- tained a small testicle about the size of that of a boy of ten years of age ; the left testicle lay like- wise external to the abdominal ring, and was still softer and smaller than the right. Both were furnished with spermatic cords. The ge- neral configuration of the individual was strong, muscular, and meagre ; the beard was thin and soft, and the face, maram;e, thorax, pelvis, and extremities were evidently masculine. Along with the preceding instances we are inclined to classify the case of Maria Nonzia, as detailed by Julien and Soules.* This indi- vidual was born in Corsica in 1695, was twice married as a female, and at last divorced in 1739 by her second husband, after having lived sixteen years in wedlock. The penis was two inches in length, but imperforate, and the mea- tus urinarius was placed at its root. Two bodies, like ordinary sized testicles, and fur- nished with spermatic cords, were felt in the divided scrotum ; and there was a narrow false vagina or perineal canal one inch and three Jines in depth, and crossed at its upper extre- mity by two small traversing membraneous bridles. The character and appearance of the person were masculine; the visage was beard- ed ; the mammae were as fully developed as in the adult woman, but the nipples were each surrounded with hair. So far as the preceding details go, they seem amply sufficient to justify us in considering Maria Nonzia as a malformed male ; and we are still inclined to take this view of the case, notwithstanding the statement inserted in the report of Julien and Soules, that the menses were present as in other women. For not to insist upon the circumstance that the reporters do not shew that they made any minute or satisfactory inquiry into this alleged fact, and not improbably took it upon the mere word of the subject of the case, who was necessarily greatly interested in maintaining the reputed female character, it would be requisite, in any such paradoxical instance, to ascertain if the discharge actually agreed in character with the menstrual fluid, or was not pure blood, the re- sult of an haemorrhage from the genito-urinary passages, or from the rectum, where, as in other parts of the body, this form of disease frequently assumes a periodical type. We would be in- clined to apply even still more strongly these remarks to the celebrated case of Hannah Wild, detailed by Dr. Sampson.-)- This person had * Observ. sur l'Hist. Nat. sur la Physique et sur la Peinture, torn. i. p. 18, with a plate. t Ephem. Nat. Curios. Dec. i. an. iii. p. 323. evidently the male genital organs malformed in the manner mentioned with regard to the other cases included under the present section, and possessed all the secondary sexual peculiarities of the male ; so that we can only receive with great doubt and distrust the alleged existence of the menstrual discharge, and the more so, as this is evidently stated on the report of the subject of the case alone, who, deriving a pre- carious subsistence from the exhibition of his malformations, had a deep interest in amplify- ing every circumstance that could enhance the public curiosity with respect to the reality of his hermaphroditic character. At the same lime, however, it must be re- marked that in some instances of spurious her- maphroditism, it is found extremely difficult or even impossible during life to determine with precision the true or predominant sex of the malformed individual ; and in regard to several well-known cases on record, we find on this point the most discrepant opinions offered by different authors. Thus while Morand,* Ar- naud,f and DeliusJ described Michel- Anne Drouart as a male ; Guyot,§ Ferrein,|| and Caldanif maintained that this person was a female; and Mertrud** regarded the individual as an example of a real hermaphrodite. A useful lesson of caution to us against our forming too decided and dogmatic an opinion in cases in which the sexual conformation ap- pears in any marked degree doubtful, has lately been offered in the instance of Maria- Dorothee Duriee, or, as this individual was named in the latter years of 'his life, Charles Durge. While Metzgerff considered this per- son as a specimen of that kind of equivocal sexual formation to which the designation of her- maphroditism is truly applicable, Hufeland,IJ Mursinna,§§ Gall, Brookes,|||| and othersllH declared the sex of Duriee to be in reality female; and Stark,*** Mertens,fft and the Members of the Faculty of Medicine at Paris J J J were equally positive in regarding the indivi- dual as merely a malformed male. The dis- section of the body of Duriee by Professor Mayer has, as we shall afterwards state more in detail, shewn the sexual conformation of this individual to consist of a true mixture of both the male and female organs. * Mem. de l'Acad. des Sc. 1750, p. 165. t Dissert, sur les Hermaphr. p. 298. J Frank, Sammlung. Th. viii. s. 398. I Mem. de l'Acad. des Sc. 1756, p. 71. II lb. 1767, p. 205. «j[ Mem. della Societa Italiaua, t. vii. p. 130. ** Arnaud, loc. cit. p. 293. tt Gericht. -medic. Abhandlungen. Bd. i. s. 177. Journ. der Praktischen Heilkunde, Bd. xii. s. 170. &§ Journ. fur die Chirurgie, Arzneikunde, &c. Bd. i. s. 555. Illl Medical Gazette for October, 1836. ^f^f Von dem Neuangekommen. Hermaphrod. Berl. 1801. *** Neuen Archiv. fur die Geburtshiilfe. Bd. ii. s. 538. fttBeschreibungder mannlichen Geschleehtslheile von M. D. Durrier. Leipzig, 1802, with two plates, ttt Med. Gaz. for October, 1836. HERMAPHRODITISM. 695 In attempting to determine the true sex in such doubtful instances of sexual formation as those which we have been now considering, we are inclined to attribute very little weight to the nature of the sexual desires of the malformed individual, as we have already found Adelaide Preville, the dissection of whose body shewed him to be in reality a man, living for some years before death in the capacity of a wife, and the same remark might be further illus- trated by a reference to Otto's and other cases. A species of spurious hermaphroditism simi- lar in character to that which we have just de- scribed in man, is occasionally met with in the males of our domestic quadrupeds, and has been amply illustrated, as it occurs in these animals, by Professor Gurlt in his work on Veterinary Medicine. In instances of this malformation among the animals to which we refer, the hypospadic male penis has usually been found of a tortuous and winding form and of small size. In the cases in which the fissure of the parts extends through the scrotum, a false vagina is seldom formed, as in man, for the scrotum in most quadrupeds lies too remote from the perineum, and consequently from the normal situation of the vagina, for this purpose; but in some examples this division appears to be carried upwards into the perinsum itself, leaving a vaginal-like opening, in which the urethra terminates. The testicles, as in man, are sometimes retained within the abdomen, and in other instances descend into the scrotum. They are frequently small in size. The mamma or udder seems to be often well developed. This variety of hermaphroditic malforma- tion has been met with in the horse by Pen- chenati;* in the he-goat by Haller;f and in the ram by the same author,J and by Wagner,§ Wepfer,|| Stark,1T Gurlt,** KauwBoerhaave,ft and A. Cooper.}! We have seen an excellent specimen of this malformation in the last- mentioned animal in the museum of Dr. Handyside of Edinburgh. In this instance the internal male organs are all perfect ; the large testicles are situated in the halves of the split scrotum ; the penis is small and imperfo- rate, and a furrow running along its inferior surface is continued backwards and upwards along the perinaeum to within a short distance from the anus, where it leads into a canal, into which the urinary bladder and seminal ducts open. This canal is evidently formed of the dilated pelvic portion of the male urethra; its orifice is comparatively contracted, but corres- ponds in situation with the vulva of the fe- male. We have seen a second similar case in * Mem. de l'Acad. de Turin, torn. v. p. 18. t Comment. Soc. Keg. Sc. Getting, torn. i. p. 2, tab. i. t Ibid. p. 5, tab. ii. 6 Ephem. Nat. Curios. Cent. i. ii. p. 235. I) Miscell. Nat. Curios. Dec. i. An. iii. (1672,) p. 255. f Ibid. Dec. iii. Ann. v. vi., p. 669. ** Lehrbuch, p. 193. tt Nov. Comment. Acad. Petropolit. torn. i. (1750,) p. 315, tab. xi. tt Catalogue of Guy's Hospital Museum, No. 2546. the ram in the possession of Professor Dick of the Veterinary School of Edinburgh. There is another variety of malformation of the male parts occasionally found in quadru- peds, which is allied in its nature to the pre- ceding. In this second species all the exter- nal male sexual organs are small ; the short penis lies, when not in a state of erection, upon the posterior surface of the enlarged udder, and the imperfectly developed testicles are ge- nerally retained within the abdomen ; or, if they have passed out of that cavity, they are found situated in the substance of the udder. The vasa deferentia, prostate, aud Cowper's glands are usually of their normal size and ap- pearance. This imperfect hermaphroditic for- mation appears to be not rare among horses, several instances of it in this animal having been now described by Arnaud,* Gohier,f VoImar,J Pallas,§ Virey,|| and Gurlt.1T An- selmo** and Lecoqft nave met with this variety of malformation in the bull ; and Sandford }J has described an instance in the calf which seems referable to the same head. Gurlt§§ also notices the preparation of an analogous case in the calf, as preserved in the museum at Berlin. II. TRUE HERMAPHRODITISM. True hermaphroditism exists as the normal type of sexual conformation in several classes of the vegetable and animal kingdom. Almost all phanerogamic plants, with the exception of those included under the class Dicecia, are fur- nished with both male and female reproductive organs, placed either upon the same flower, or, as in the Linnaean class Moncecia, upon different flowers in the same individual. In the class Polygamia various exceptional genera are included, that present indiscriminately upon the same individual, or upon different indivi- duals of the same species, male, female, and hermaphrodite flowers, and which thus form a kind of connecting link between the general hermaphroditic form of phanerogamic vegeta- bles, and the unisexual type of the monoecious flowers, and the dioecious plants. From anormalities in developement, these normal conditions of the sexual type in the different members of the vegetable kingdom are occasionally observed to be changed. Thus, among the Dicecia, individual plants are some- times, in consequence of a true malformation, observed to assume an hermaphroditic type of structure ; or, on the other hand, in hermaphro- ditic plants more or fewer flowers are occa- * Arnaud sur les Hermaphrodites, p. 282. t Mem. et Observ. sur la Chir. et la Med. Vet. torn. i. p. 18. t Archiv. fur Thierheilkunde, Bd. iii. s. 292. § Ueschaft. der Gesellschaft naturforcb. Freunde zu Berlin, Bd. iii. s. 296. |J Journal Compl. des Sc. Med. torn. xv. p. 140. II Lehrbuch der Path. Anat. 13d. ii. p. 189 ; and tab. viii. fig. 6. ** Mem. del' Acad, des Sc. de Turin, torn. ix. p. 103. fig. 1-3. tt Journ. Prat, de Med. Vet. 1827, p. 102. tt Med. and Phys. Journal, vol. ii. p. 305, with two drawings. §§ Loc. cit. p. 191. 6V6 HERMAPHRODITISM. sionally found unisexual, in consequence of the arrested developement of one order of their sexual organs ; and again, though still more rarely, from an excess of evolution, a double set of male parts, or a double set of stamens, is seen developed on some of the individual flowers. In the animal kingdom we find instances of a perfect hermaphroditic structure as the normal form of the sexual type in the Trematodes and Cestoides among the Entozoa, in the abranchial Annelida, in the Planaria, and in many of the Mollusca, particularly in the Pteropoda, and in several families among the Gasteropoda. In some of these animals that are thus naturally hermaphroditic, the fecundation of the female organs of the bisexual individual is accom- plished by its own male organs; but in others, although the anatomical structure is strictly her- maphroditic, yet the union of two, or, as some- times happens, of more individuals is neces- sary to complete the sexual act ; and during it the female organs of each are respectively im- pregnated by the male organs of the other. In the Nematodes and Acanthocephali among the Entozoa, and in the Cephalopoda and Pecti- nibranchiate Gasteropoda among the Mollusca, as well as in all symmetrically formed animals, or, in other words, in those whose bodies are composed of an union of two similar halves, as in Insects, and the Arachnida, Crustacea, and Vertebrata, the male and female organs of re- production are placed each upon a different individual of the species, constituting the ba- sis of distinction between the two sexes. In such animals a mixture of more or fewer of the reproductive organs of the two sexes upon the same individual appears occasionally as a result of abnormal formation ; but the male and female organs that coexist in these cases are seldom or never so anatomically perfect as to enable the malformed being to exercise the proper physiological function of either or of both of the two sexes. This form of true her- maphroditism or abnormal mixture upon the same individual of the organs of the two sexes in the higher animals, has been termed unnatu- ral or monstrous, in opposition to the natural hermaphroditism which exists as the normal type of sexual structure in some of the lower orders of animals, and in phanerogamic plants. The malformation itself is observed to differ greatly, both in nature and degree, in different cases, varying from the presence or superaddi- tion of a single organ only of theoppositeor non- predominant sex, up to the development and co-existence of almost all the several parts of the two sexes upon the same individual. In describing the malformation, we shall classify its various and diversified forms under the three general orders pointed out in our table, including, 1st, lateral ; 2dly, transverse ; and 3dly, double or vertical hermaphroditism. A. Lateral hermaphroditism. — According to the opinion of many physiologists of the pre- sent day, the two lateral symmetrical halves of the body, and even the two halves of all its single mesial organs, are originally developed in a great degree independently of one another. Granting this point in the doctrine of eccentric developement, we can easily conceive how, in the same embryo, an ovary might be formed on one Wolffian body, and a testicle on the other; or, in other words, how female organs might be developed on one side, and male organs on the other. It is the existence of such an unsymme- trical type of sexual structure upon the two op- posite sides of the body of the same individual, that constitutes the distinctive characteristic of lateral hermaphroditism. Instances of this species of true hermaphro- ditic malformation have been observed in many different classes of animals, as well as in the human subject. Individual examples are sometimes observed among insects, particularly among the Lepido- ptera, in which all the different parts of the two sides or lateral halves of the body are formed after opposite sexual types. We shall after- wards have occasion to notice different exam- ples of this form of lateral hermaphroditism as seen in the general conformation of the body, but may here state that in two or three in- stances such malformed insects have been care- fully dissected, and found to present, in the ana- tomical structure of their sexual organs, a mix- ture of the organs of the male and female. In a MelitcBu didymus described by Klug,* the general external characters were those of the male, but the left eye, palpus, and antenna, and the left sexual fang, were smaller than in individuals belonging to this sex ; and the left antenna was annulated with white and yellow at the apex, while the right was of one colour. On dissection, the various male sexual parts were present, and they had appended to them a free female ovary situated upon the left, and united to no other organ. In a Gastrophaga quercifolia dissected by Schultz, and described by Rudolphi,f the left side appeared externally male, and the right female, with a distinct line of separation through- out the whole body. On dissection, Schultz dis- covered an ovarium upon the right side, and two testes upon the left. The oviduct of the ovary joined the canal of the vasa deferentia about two inches before its termination; and the spermatheca was connected with the com- mon evacuating duct. The two testicles on the left side were placed one behind the other, and connected by a thin vessel. The spermatic duct belonging to one of the testicles imme- diately received, as in the Lepidoptera, the spi- ral vessel ; further beyond, and on the opposite side, a second vessel, which appeared to con- sist of the rudimental spermatic duct of the other testicle, opened into it. The oviduct of the ovary joined the canal of the vasa deferen- tia about two inches before its termination in the penis, and a female spermatheca was con- nected with the common distended evacuating duct. I * Fioriep's Notizen, vol. x. p. 183. t Abhandlung. der Koenig. Akad. zu Berlin fur 1825, s. 55. f See also drawings of the body and genital or- gans of an hermaphrodite Sphinx populi in Fischer's Oryctographie du Gouveinement de Moscou (Mos- cow, 1830..) HERMAPHRODITISM. 697 A well-marked example of lateral herma- phroditism among the Crustacea has been re- corded by Dr. Nicholls.* In a lobster (Anta- eus murium ) he found on the right side of the body a female sexual aperture in its normal situation at the root of trie third leg, and con- nected with a regularly formed oviduct, full of ova. On the left side of the animal there was a male sexual aperture placed, as usual, at the root of the fifth leg, and connected internally with an equally perfect testicle and spermatic cord. The general external conformation of the animal corresponded with its internal sexual structure, the right lateral half of the body presenting all the secondary characters and pe- culiarities of the female, and the left all those of the male; so that if split from head to tail, (to use Dr. Nicholls' mode of expression,) the animal would have been perfectly female on the right side, and perfectly male on the left. The investigations of Sir E. Homef led phy- siologists some years ago to believe that among Fishes lateral hermaphroditism constituted the natural type of sexual formation in the genera Myxine and Petromyzon ; but the later and more accurate observations of RathkeJ have shewn that these species are strictly bisexual, and that the opposite opinion had arisen from the kidneys of the female having been mistaken for the male testicles. Various instances, how- ever, are on record of fishes, known to be nor- mally bisexual, presenting from abnormal deve- lopement a lateral hermaphroditic structure, or a roe on one side, and a milt on the other. Such an hermaphroditic malformation has been met with in the genera Salmo,^ Gadus,\\ and Cy- prinus*\ and in the Merlangus vulgaris,** Aci- penser husorff and Esox lucius-H Of lateral hermaphroditism in Birds, we have * Phil. Trans, for 1730, no. 413, vol. xxxvi. p. 290, with drawings of the animal, and of its repro- ductive organs. t Phil. Trans, for 1823. Art. xii. X Bemerkungen ueber den Innern Bau der Pricke, s. 119. See also additional observations by the same author in Miiller's Arcliiv fur Anatomie, &c. for 1836. Heft. ii. s. 171. The older error of Cavolini, who supposed that he had detected two ovaries and two testicles in the Perca marina and Labrus channa, (Sulla Generazione dei Peschi et dei Granchi, Nap. 1787,) had been previously shewn by Rudolphi to depend upon his having mistaken undeveloped portions of the ovaries for testicles. (Schweigger's Skeletlose Thiere. s. 204; and Ab- handlungen. Konig. Akad. der Wissenschaft zu Berlin, 1825. p. 48.} $ Commerciurn Litter. Norim. 1734. Hebd. 39. ]| Pipping, Vetensk. Akad. nya Handl. (1800.) Bd. xxi. s. 33. tab. i. fig. 1. Leuwenhoeck, Ex- perim. et Contempl. p. 150. Eph. Nat. Cur. Dec. i. Ann. i. obs. 125. Du Hamel, Traite des Poissons, Part ii. p. 130. 11 Alischer, Breslau. Sammlung. 1720, p. 645 ; Morand, Mem. de l'Acad. des Sc. 1737. p. 72. Schwalbe, Commer. Lit. Norimb. 1734. p. 305. ** Marchant, Mem. de l'Acad. des Sc. 1737. p. 12. Baster, Opusc. Subcesiva, torn. i. p. 138. +t Pallas, Reise durch Russe, &c. Theil. ii. s. 341. ft Reaumur, Mem. de l'Acad. 1737. p. 51. Starke, Eph. Nat. Cur. Dec. iii. ann. vii. and viii. obs. 109. one instance recorded by Bechstein,* in a chicken that had a testicle on the right side of the body, and an imperfect reniform ovary on the left. The external appearance of the bird presented a mixture of the characters of the two sexes. Rudolphi has referred to a second and more ancient example of lateral hermaphroditism in the hen, mentioned by Ileide.f The case, en- titled by the author " galli qui putabatur her- maphroditus anatome rudis," is so imperfectly detailed as not to be entitled to much attention. We have ourselves been fortunate enough to meet with two domestic fowls that presented in their sexual organization examples of lateral her- maphroditism. In the first of these cases (fig. 290) the female sexual organs were placed on the Fig. 290. left side of the body, and the ovary (a) and ovi- duct (b) were in all respects apparently natu- rally formed. On the right side, a male vas deferens («) was vesicular. Mayer, in the work already referred to,* has described and delineated the following five cases of the present species of hermaphroditic malformation in the human subject, all of which he had himself met with and dissected. /". In a fcetus of the fourth month, and affected withomphaloceleand extroversion of the urinary bladder, lie found male testicles (fig. 302, Fig. 302. a a) with their epididymes (b b), and a two- horned uterus (c) terminating in a vagina (tf), that opened into the posterior part of the uri- nary bladder (e). From the left testicle a con- torted vas deferens ( /) arose,and ran down to the vagina; the right vas deferens (g) was shorter, * Icones Select. &c. p. 8-16. See also Walther and Giaefe's Journal der Chirurgie und Augen- heilkunde, Bd. vii. lift. 3, and I3d. viii. Hft. 2. and became thread-like, and disappeared near the corresponding cornu of the uterus. A ru- diment only of the left male vesicula seminalis was observable. The external organs were male ; the glans penis (h) was imperforate. g. In another fcetus of the sixth month,* there existed a perfect set of internal and exter- nal male sexual organs, viz., testicles, epididy- mes, vasa deferentia, and vesicul* seminales, with a prostate gland and a normally formed penis and scrotum. But besides these, there was also present an imperfect female uterus, the body of which divided into two cornua, the right longer and incurvated, the left shorter and sacciform. The neck of the uterus was marked internally by its usual arborescent appearance ; and it opened into a vagina that terminated in the urethra near the exit of the latter from the urinary bladder. h. In a third casef of hermaphroditic malfor- mation in an infant who diedof convulsions when six months old, Mayer found the following blend- ing of the organs of the two sexes. Of the internal male genital organs there were present two bodies at the inguinal rings that were evi- dently testicles, {fig. 303, a, a) as was proved Fig. 303. not only by their position, but by their form, coverings, connections, and internal structure, (" theirsubstance," says Mayer, " being evident- ly composed of yellow canals"); their epidi- dymes (b b) were also distinctly developed, and each of them sent off a vas deferens (c c), which * Icones, p. 8. tab. ii. fig. 5. t Icones, p. 9, tab. iii. fig. 1 and 2. *j HERMAPHRODITISM. 711 was furnished with a corresponding multilocular vesicula seminalis (d d). Of the internal fe- male sexual organs there were found a perfectly developed uterus (e e), with its broad (« w) and round (u o) ligaments naturally formed and placed, and provided with two Fallopian tubes (ff) that followed the course of the testicles through the inguinal canals, and a va- gina (g) which opened into the urethra (//) near its external orifice. The ejaculatory ducts of the male vesicula? seminales opened into this vagina at I and m. The internal surface of the vagina was already beginning to present the appearance of its usual rugae. The cavity of the uterus was triangular, and exhibited on the internal part of the cervix its characteristic plicated or arborescent structure. The Fallo- pian tubes were, at their uterine orifices, of a large caliber; their cavity afterwards became suddenly contracted, and then again ddated, and terminated at their ulterior extremities, where they lay in contact with the testicles at the external inguinal rings, in blind sacs (i i), without any very distinct appearance of fim- bria;. The external genital parts in this very interesting case were of a doubtful nature, being referable either to those of a hypospadic male, or of a female with a large clitoris, but without nympha;, the meatus urinarius being in its normal situation, but leading behind to the cavities of both the urinary bladder and uterus. The circle of the pelvic bones was large. i. The two other instances described by Mayer occurred in adult subjects, and the mal- formation in both of them differed from that found in the cases just now cited in this, that there was only one testicle present along with the imperfect uterus. The subject of one of these cases* was a person who died at the age of eighteen, and whose external sexual organs were those of a hypospadic male, with a narrow perinaeal canal or fissure. On dissection this perinaeal canal was found to communicate anteriorly with the urethra, and posteriorly with a vagina of two inches and nine lines in length, and five or six lines in caliber. The anterior and posterior column of rugae belonging to the vagina was only slightly marked. Its canal led to a large dilated uterus, the superior part of which was unfortunately cut away with some dis- eased viscera before the genital organs were examined; but, from the portion left, this organ seemed to resemble the uterus of quad- rupeds in its oblong form, and in the thinness of its walls, which were composed of a caver- nous fibro-vascular texture, and full of lacunas. The usual arborescent appearance of the inter- nal surface of the os uteri was very perfectly marked. Besides these female organs, there was a well-formed male prostate gland at the neck of the bladder ; and behind the abdomi- nal ring of the right side, a small roundish body, similar in form and texture to the testi- cle, and having the cremaster muscle adhering to its membranous involucrum. There were no traces of any similar organ on the left side. * Iconcs, p. 11. tab, iii. fig. 3 and 4. On both sides some portions of a crural were seen, but whether they were the remains of the vasa deferentia or Fallopian tubes was not ascertained on account of the previous mutilation of the uterus. On each side of the neck of the uterus there was placed a vesicula seminalis, provided with an ejaculatory duct that opened into the orifice of the vagina. The dimensions of the pelvis approached much nearer to those of the female than those of the male. In the secondary sexual characters of the individual, the female type was further re- cognised in the want of prominence in the larynx, in the slender form of the neck, and (according to Professor Mayer) in the rounded shape also of the heart, the smallness of the lungs, the oblong shape of the stomach, the large size of the liver, the narrowness of the forehead, and the conformation of the brain ; while the individual approximated, on the other hand, to the male in the length and posi- tion of the inferior extremities, in the breadth of the thorax, the undeveloped state of the mammae and the hairy condition of their pa- pillae, and in the existence of a slender beard upon the chin and cheeks. j. In the second adult subject (a person of eighty years of age) Mayer* found, on the left side of the cavity of the abdomen, and near the inguinal ring, a small oval body exhibiting imperfectly in its internal structure the tubular texture of the male testicle, and having an appendix resembling the epididymis attached to it. From this testicle arose a vas deferens, which was joined in its course by a vesicula seminalis, and ended in an ejaculatory duct. On the opposite or right side a vesicula semina- lis, having no continuous cavity, was present ; but no vestige of a corresponding testicle, vas deferens, or ejaculatory duct could be disco- vered. The prostate gland was present, and regularly formed. In the cavity of the pelvis an uterus was found with parietes of moderate thickness, and of the usual cavernous texture; its cervix was marked internally with the appear- ance of the natural arborescent ruga?. Inferiorly it opened into a narrow membranous vagina, that received the right ejaculatory duct, then passed through the body of the prostate, and latterly joined the canal of the urethra. The fundus of the uterus could not be examined, as it had been removed in a previous stage of the dissection. The external parts were male and naturally formed, with the exception of the penis, which was shorter than usual, and had the canal of the urethra fissured inferiorly, and the meatus urinarius situated at its root. The individual was during life regarded as a male, but had all along remained in a state of celi- bacy. The general appearance of the face and body was that of an imperfectly marked male, but the pelvis was broad like that of a female. 3. Co-existence of J cm ale ovaries and male testicles. — This third division of complex or double hermaphroditism includes all those cases in which a male testicle and female ovary exist together either upon one side only, or upon * Iconcs, p. 15, tab. iv. fig. 1 and 2» 712 HERMAPHRODITISM. both sides of the body. With this arrange- ment, other malformations by duplicity of the sexual organs are generally combined ; but these are so various in their character as not easily to admit of any useful generalization. In considering this third division of complex hermaphroditism, we shall mention, first, the cases in which two testicles and one. ovary are stated to have co-existed ; and secondly, those in which there have been supposed to be pre- sent two testicles and two ovaries. Two testicles and one ovary.- — The two dis- sections that we have previously detailed of lateral hermaphroditic insects, ( see Lateral Hermaphroditism, p. 696,) shew that in these two cases this variety of sexual duplicity existed. It appears to have been observed also in two instances of hermaphroditic malformation in the quadruped, the histories of which have been described by Mascagni and Mayer. In a bull, nine years of age, and which was provided with the usual external organs of the male, Mascagni found internally, on dis- section, a prostrate gland and two perfect vesicular seminales, vasa deferentia, epidi- dymes, and testicles. The testicles and epi- didymes were injected with mercury through the vasa deferentia. In addition there was dis- covered near the left testicle, and connected to it by peritonaeum and bloodvessels, a body having the structure of the female ovary ; and, in its normal situation, there existed a distended double uterus, containing from fifteen to sixteen pounds of a clear fluid. This uterus was furnished with two Fallopian tubes at its upper part, and terminated inferiorly in a vagina, which opened by a small orifice into the male urethra.* In a goat dissected by Mayer, f he found two testes with their epididy mes fully developed, and vasa deferentia and vesiculae seminales. One of the testes was placed without and the other still remained within the abdominal cavity. At the same time there were present a large fe- male vagina communicating with the urethra, and a double- horned uterus provided with two Fallopian tubes. One of these tubes terminated in a blind canal, but the other had placed at its abdominal extremity several vesicles, resem- bling, according to Mayer, Graafian vesicles, or an imperfect ovary. The vesicute seminales and (through regurgitation by the urethra and ejaculatory ducts) the cavities of the vagina and uterus, were filled with about four ounces of a whitish fluid, having the colour and odour of male semen. This fluid could not be found by the microscope to contain any seminal ani- malcules, but only simple and double Monades ( Monades termones et guttulas ). Bergmann, however, is alleged to have found it, on analysis, to contain the same chemical principle that characterizes human male semen. Two testicles and two ovaries. — Various in- stances have now been published in which this sexual duplicity has been supposed to exist * Atti dell' Acad, delle Scienze di Siena, t. viii. p. 201. t Icones, p. 20. among cattle and other domestic quadrupeds, as well as in the human subject. One of the free-martins* described by Mr. Hunter comes under this variety. In the case referred to, in the situation of the ovaries " were placed," to use Mr. Hunter's words, " both the ovaria and testicles," — or, as Sir Everard Home, in alluding to this case, more justly expresses it, " an appearance like both testicles and ovaria was met with close toge- ther."! The two contiguous bodies were nearly of the same size, being each about as large as a small nutmeg. There were no Fallopian tubes running to the ovaries, but a horn of an imperfect uterus passed on to them on each side along the broad ligament. Pervious vasa deferentia were found ; they did not, however, reach up completely to the testicle on either side, or form epididymes. The vesicula; semi- nales were present, and much smaller than in the perfect bull. The external parts appear to have been those of the cow, but smaller than natural. The vagina passed on, as in the cow, to the opening of the urethra, and, after having received it and the orifices of the seminal ducts, it began to contract into a small canal, which ran upwards through the uterus to the place of division of that organ into its two horns. Velpeau,t in his work on Midwifery, men- tions that in an embryo calf, he had " found reunited the testicles and ovaries, the vasa deferentia, and uterus." In an hermaphroditic foal-ass, Mr. Hunter§ found both what he considered to be two ovaries placed in the natural situation of these bodies, and two testicles lying in the inguinal rings in a process or theca of peritonaeum similar to the tunica vaginalis communis in the male ass. No vasa deferentia or Fallopian tubes could be detected ; but there was a double-horned uterus present, and from its broad ligaments, (to the edges of which the comua uteri and ovaries were attached,) there passed down on either side into the inguinal rings a part similar to the round ligament in the female. The horns and fundus of the uterus were pervious ; but its body and cervix, and the canal of the vagina from above the opening of the urethra into it, were imperforate. The external parts were similar to those of the female ass ; but the clitoris, which was placed within the entrance of the vagina, was much larger than that of a perfectly formed female ; it measured about five inches. The animal had two nipples. Scnba has given an account|| of an herma- phroditic sheep, in which two large testicles are stated to have been found in the scrotum, at the same time that there existed, in their nor- mal situation, two moderately sized ovaries, and a small uterus furnished with two appa- rently closed Fallopian tubes. The external sexual parts appear to have been those of a * An. Econ. p. 63-64, pi. ix. t Comp. Anat. vol. iii. p. 322- | Traite de l'Art des Accouchemens, t. i. p. 114. & An. Econ. p. 58. \\ Schrifteu dtr Gesellschaft Naturforschendcr Fieude zu Berlin, Bd. x. s. 367. HERMAPHRODITISM. 713 malformed male, the penis being short and im- pervious, the scrotum divided, and the urethra opening into a contracted perineal fissure re- sembling the female vulva. This animal had often attempted connection with the female sheep. Borkhausen* has described a very similar case in the same species of animal. Each half of the divided scrotum contained a testicle which was regularly formed, but greater in size than usual, and furnished with a large sperma- tic artery. The pelvis contained a normal uterus, which was smaller, however, than na- tural ; it was provided with its usual ligaments. The Fallopian tubes were present but imper- forate, and the two ovaries were full of vesicles and inclosed in a strong membrane. The vagina was natural and opened as in the female. Behind the divided scrotum the rudiment of an udder with four teats (instead of two) was situated. The male penis was also present, but diminutive and short; its erectores muscles were small, and the prostate gland indistinct. The urethra was single as it left the bladder, but it afterwards divided into two canals, the wider of which opened into the female vagina and vulva, and the narrower ran through the male penis. The urine passed in a full stream through the former canal, and only by drops through the latter. The animal is alleged to have attempted coition in both ways. In 1829, an account of an hermaphroditic goat was published at Naples, which is said to have been provided with both female ovaries and male testicles.f The two ovaries occupied their usual situation ; no Fallopian tubes were found ; but there were present a double-horned uterus with blind cornua, and a vagina which opened externally, as in the female. In the neighbourhood of the ovaries, and more ex- ternal than them, two small testicles were dis- covered, having two vasa deferentia arising from them. The vasa deferentia ran down- wards to two corresponding vesicular seminales, that were placed alongside of the uterus. In the lower angle of the external pudenda, a body, resembling in length the male penis more than the female clitoris, was situated : it was, as we have already had frequently occasion to mention in regard to the penis in malformed male quadrupeds, of a very tortuous or con- voluted form. We have had an opportunity of examining an excellent preserved specimen of double herma- phroditism in the sow, referable to the present section, which was met with some years ago by Dr. Knox, and we have his permission to state here the following particulars of the case. Among the internal female organs there is present a natural well-formed double uterus, provided with broad ligaments and two hollow cornua, each about six or seven inches in length. The fimbriated extremities are not distinctly marked, the female tubes appearing to end * Rheinisches Mag. zur Erweiterung tier Natur- kunde. Giesscn 1793. Bd. i. s. 608. t Brevi ccnne su di un Neulvo Capro; or, Gurlt's Patholo^ischen Anatomie, Bd. ii. s. 198. blind at their upper terminations, as they have often been observed to do in similar cases. The os uteri opens inferiorly into a vagina, which seems normal in its structure. At a short distance from the upper extremity of each horn of the uterus, two bodies of considerable magnitude are seen lying in close juxta-position. The smaller of these two bodies is on either side about the size and shape of a large almond ; and though internally of an indeterminate amorphous structure, they are considered by Dr. Knox as answering to the two ovaries. The two larger bodies, which are placed between the supposed ovaries and the upper extremities of the cornua uteri, are most dis- tinctly testicles, as shewn by their numerous tor- tuous seminiferous tubes, which have been suc- cessfully filled with a mercurial injection. They are of the full size of the organ in the adult male. The seminiferous tubes of each testicle terminate in a vas deferens, which was injected from them ; and the two vasa deferentia run downwards through the ligamenta lata of the uterus, and terminate inferiorly in the upper- part of the vagina, thus following the course of those natural canals in the female sow that we shall afterwards have occasion to allude to at greater length under the name of Gaertner's ducts, and which Dr Knox, from the evidence of the present case, believes to be in reality typical of the male vasa deferentia. There is no trace of vesicular seminales. Externally the vagina opened along with the urethra upon the perinoeum, at a point lower than natural in the well-formed female. The clitoris in situa- tion and size was nearly normal. The animal at the time of death was fourteen months old ; it was ferocious in its habits ; and it had been in vain tried to be fattened. It had repeatedly shewn strong male propensities, and at the season of heat its vagina is said to have presented the usual injected appearance ob- served in the female sow. Dr. Harlan of Philadelphia* has lately described a still more perfect instance of dou- ble hermaphroditism than any of the preceding, which he met with in the body of a gibbon or orang outang, from the Island of Borneo ( Simla concolor ). This animal died of tuber- cular disease in Philadelphia in 1826, when it was considered to be under two years of age. Dr. Harlan gives the following account of its sexual formation. The penis (jig.ZO^, a) was about one inch in length, and subject to erec- tions ; it terminated in an imperforate glans ; and a deep groove on its inferior surface served as a rudimentary urethra. This groove extended about two-thirds of the length of the penis, the remaining portion being covered with a thin articular diaphanous membrane, which extended also across the vulva (fc), and closed the external orifice of the vagina. The vagina was rather large, and displayed transverse striae. Traces of the nymphte and labia externa were visible. The meatus urinarius opened beneath the pubis into the vagina, but the urine must have been directed along the groove of the penis by the * Med. and Pliys. Researches, p. 19. 714 HERMAPHRODITISM. Fig. 304. External sexual organs and testicles. ' gg, the prepuce ; hh, the vasa deferentia ; i, the anus ; kh, ischiatic protuberances. membrane obstructing the orifice of the vulva. The os tincoe was surrounded by small globular glands. The orifice and neck of the uterus admitted a large probe into the cavity of that organ, which appeared perfect with all its ap- pendages. The round and broad ligaments, together with well-developed ovaries (jig. 305, b b), were all found in situ. The scrotum Fig. 305. Internal sexual organs seen from hehind. d, the urinary bladder ; ff, rectum j gg, broad ligaments ; cc, Fallopian tubes. (fig. 304, c) was divided, and consisted of a sac on each side of the labia externa, at the base of the penis, covered with hair. The testicles (fig. 304, d d) lay beneath the skin of the groin about two inches from the symphysis pubis, obliquely outwards and upwards : they appeared to be perfectly formed with the epi- didymis (J[f), &c. The most accurate examina- tion could not discover vesiculae seminales ; but an opening into the vagina, above the meatus urinarius, appeared to be the orifice of the vas deferens. In all other respects the male and female organs of generation were in this animal as completely perfected as could have been anticipated in so young an individual, and resembled those of other individuals of a similar age. Two imperfect instances are on record of the co-existence of male testicles and female ovaries in the human subject. a. The first of these cases is detailed by Schrell.* It occurred in an infant who died when nine months old. All the internal and external male organs were present and perfectly formed, with the exception of the prepuce of the penis, which seemed divided in front and rolled up. At the root of the large penis, was a small vulva or aperture capable of admitting a pea, and provided with bodies having an appearance of labia and nymphse. This vulva led into a vagina that penetrated through the symphysis pubis, and terminated in a nipple-like body or imperfect uterus, to which, structures having a resemblance to the Fallopian tubes and ovaries were attached. b. The other and still more doubtful case of the alleged existence of both testicles and ovaries in the human subject, was first pub- lished by Beclard.f The case was met with by M. Laumonier of Rouen, who injected and dissected the sexual parts, and deposited them in a dried state, along with a wax model repre- senting them in their more recent condition, in the Museum of the School of Medicine at Paris. In the wax model two female ovaries with an uterus, vagina, external vulva, and large imperforate clitoris, are seen combined with two male testicles, the vasa deferentia of which terminate in the uterus at the place at which the round ligaments are normally situ- ated ; these ligaments themselves are wanting. The preparation of the dried sexual parts is far from being equally satisfactory, and, in its present imperfect condition at least, does not bear out by any means the complete double her- maphroditic structure delineated in the model. III. HERMAPHRODITISM AS MANIFESTED IN THE GENERAL CONFORMATION OF THE BODY, AND IN THE SECONDARY SEXUAL CHARAC- TERS. In the preceding observations we have prin- cipally confined ourselves to the description of hermaphroditic malformations as seen in the resemblance in appearance and structure of the * Schenk's Medic. Chirurg. Archiv. Bd. i. s. t Bullet, de la Fac. de Med. 1815, p. 284 ; or, Diet, des Sc. Med. x.\i, p. 111. HERMAPHRODITISM. 715 external genital parts of one sex to those of the other, and in the different degrees and varieties of reunion or co existence of the reproductive organs of the two sexes upon the body of the same individual. Hermaphroditism, however, may appear not only in what are termed the primary sexual parts or characters, or, in other words, in the organs more immediately subser- vient to copulation and reproduction, but it may present itself also in the secondary sexual characters, or in those distinctive peculiarities of the sexes that are found in other individual parts and functions of the economy, as well as in the system at large. We have occasionally an opportunity of observing some tendency to an hermaphroditic type in the general system, without there being any very marked corre- sponding anormality in the sexual organs them- selves, but it rarely happens that there exists any hermaphroditic malformation of the primary organs of generation, without there being con- nected with it more or less of an hermaphrodi- tic type in the secondary sexual characters ; and this circumstance often offers us, in indivi- dual doubtful cases, a new and perplexing source of fallacy in our attempts to determine the true or predominating sex of the malformed individual. Before, however, describing that variety of hermaphroditism which manifests itself in the general system and in the secon- dary sexual peculiarities, it will be necessary, in order to understand its nature and origin, to premise a few remarks on the dependence and relation of these secondary characters upon the normal and abnormal conditions of the primary sexual organs. That the various secondary sexual peculiari- ties which become developed at the term of puberty are intimately dependent upon the changes that take place at the same period in the organism of the female ovaries and male testicles, seems proved by various considera- tions, particularly by the effect produced by original defective development and acquired disease in these parts, and by the total removal of them from the body by operation. In consi- dering this point we shall speak first of the effects of the states of the ovaries upon the female constitution, and shall then consider those of the testicles upen the male. When the usual development of the ovaries at the term of puberty does not take place, the se- condary sexual characters which are naturally evolved in the female at that period do not pre- sent themselves; and this deficiency sometimes occasions an approach in various points to the male formation. Thus in a case recorded by Dr. Pears,* of a female who died of a pectoral affection at the age of twenty-nine, the ovaries on dissection were found rudimentary and in- distinct, and the uterus and Fallopian tubes were present, but as little developed as before puberty. This individual had never menstru- ated nor shewed any signs, either mental or corporeal, of puberty. The mammas and nip- ples were as little developed as those of the male subject. She had ceased to grow at ten * Phil. Trans, for 1805, p. 225. years of age, and attained only the height of four feet six inches. In another analogous instance observed by Renauldin,* scarcely any rudiments of the ovaries existed, and the body of the uterus was absent, but the external genital female organs were well formed. The individual who was the subject of this defective sexual development had never menstruated ; the mamma were not evolved ; in stature she did not exceed three and a half French feet; and her intellect was imperfectly developed. In reference to these and other similar in- stances that might be quoted,! it may be ar- gued that they do not afford any direct evidence of the evolution of the sexual characters of the female depending upon that of the ovaries, as the arrestment in the development of both may be owing to some common cause which gives rise at the same time to the deficiency in the development of the genital organs, and to the stoppage of the evolution of the body in gene- ral. That the imperfection, however, in the organism of the ovaries may have acted in such cases as the more immediate cause or precedent of the imperfection or non-appearance of the secondary characters of the sex, seems to be rendered not improbable, in regard to some, if not to all the instances alluded to, by the fact that the removal of these organs before the period of puberty, as is seen in spayed female animals, entails, upon the individuals so treated, the same neutral state of the general organiza- tion as was observed in the above instances ; or, in other words, we have direct evidence that the alleged effect is capable of being produced by the alleged cause ; and further, when in cases of operation or disease after the period of puberty, both ovaries have happened to be de- stroyed, and their influence upon the system consequently lost, the distinctive secondary characteristics of the female have been observed also to disappear in a greater or less degree. Thus in the well-known case recorded by Mr. Pott, % the catamenia became suppressed, the mammae disappeared, and the body be- came thinner and more masculine, in a healthy and stout young woman of twenty-three years of age, whose two ovaries formed hernial tu- mours at the inguinal rings, and were, in con- sequence of their incapacitating the patient from work, both removed by operation. Many facts seem to show that the act of menstruation most probably depends upon some periodical changes in the ovaries, if not, as Dr. Lee§ supposes, in the Graafian vesicles of these organs; and when the function be- comes suddenly and permanently stopped in a * Seances de l'Acad. Roy. de Med. 28 Fevrier 1826, and Medical Repository for 1826', p. 78. t Davis, in his Principles and Practice of Obste- tric Medicine, p. 513, refers to several instances in point. We may mention that Dr. Haighton found that after the Fallopian tubes were divided in rab- bits, the ovaries became gradually atrophied, and the sexual feelings were lost. Phil. Trans, for 1797, p. 173. t Surgical Works, vol. iii. p. 329. § Article Ovarv in Cyclo. of Pract. Med. 716 HERMAPHRODITISM. woman at the middle period of life, without any indications of the catamenial fluid being merely mechanically retained, we may perhaps suspect with reasonable probability the exist- ence of a diseased state which has destroyed either successively or simultaneously the func- tions of both ovaries. In such a case the dis- tinctive secondary peculiarities of the female sex come to give place to those of the male. Thus Vaulevier mentions an instance in which menstruation suddenly ceased in a young and apparently healthy woman ; no general or local disease followed ; but soon afterwards a perfect beard began to grow upon her face.* Again, in women who have passed the period of their menstrual and child-bearing life, and in whom consequently the functions and often the healthy structure of the ovaries are lost or destroyed, we have frequently an opportunity of observing a similar tendency towards an assumption of some of the peculiarities of the male ; an in- crease of hair often appears upon the face, the mamma? diminish in size, the voice becomes stronger and deeper toned, the elegance of the female form and contour of body is lost, and frequently the mind exhibits a more determined and masculine cast. Women, both young and aged, with this tendency to the male cha- racter, are repeatedly alluded to by the Roman authors under the name of viragines ; and Hip- pocrates f has left us the description of two well-marked instances. Among the females of the lower animals a similar approach to the male character in the general system not unfrequently shows itself as an effect both of disease and malformation of the sexual organs, and also in consequence of the cessation of the powers of reproduction in the course of advanced age. Female deer are sometimes observed to become provided at puberty with the horns of the stag,! and such * Journ. de Med. torn. lxix. and Meckel in Reil's Arch. Bd. xi. s. 275. Meckel quotes other similar cases from Seger in Ephem. Nat. Cur. Dec. i. Ann. ix. and x. obs. 95; Vicat, sur la Plique Polonaise, in Murray's Pr. Bibl. Bd. i. s. 578.'; and Schurig's Parthenologia, p. 184. Burlin pub- lished an express treatise on the subject, De barba mulierum ex menstruorum suppressione, Altorf. 1664. See also Haller's Elem. Phys. torn. v. p. 32 ; Reuss, Repert. Comment, torn. x. p. 205 ; Eble, Die Lehre von den Haaren in der organischen Natur. Bd. ii. s. 222. Vien. 1831 ; and Mehliss, Ueber Virilescenz und Rejuvenescenz thierischer Korper. Leipz. 1838, who quotes several cases additional to those of Meckel. * De Morb. Vulg. lib. vi. ss. 55, 56. " Abderus Phaetusa, Pythei conjunx, antea per juventam fcecunda erat ; viro autem ejus exortante, dinar- ticulos exorti sunt. Quae ubi contigerunt, turn cor- pus virile, turn in universum hirsutum est reddi- tum, barbaque est enata, et vox aspera reddita. Sed cum omnia quae ad menses deducendos facerent tentassemus, non profluxerunt, verum hand ita multo post vita funcla est. Idem quoque in Thaso Namysiae, Gorgippi conjugi, contigit." Hippocr. Op. ed. Foesii, p. 1201. % Camden's Angl. Norm. (1603) p. 821. Lan- celot Eph. Nat. Cur. Dec. i. ann. ix and x. obs. 88. Ridinger's Abbild. Seltener Thiere Taf. 79, or Meckel in Reil's Archiv. fur die Physiol. Bd. xi. p. 273. animals are generally observed to be barren,* probably in consequence either of a congenital or acquired morbid condition of their ovaries or other reproductive organs. In old age, also, after the term of their reproductive life has ceased, female deer sometimes acquire the horns of the male in a more or less perfect de- gree ;f and Burdach alleges that roes sometimes become provided with short horns when they are kept from the male during the rutting sea- son, and at the same time furnished with abun- dant nourishment.! Mehliss § alludes to two cases in which a virilescent type was shewn principally in the hair of the female deer. In one of these instances the hair of the head, neck, and abdomen, the shape of the ears and extremities, and the odour of the animal, gave it the closest resemblance to the male, and it followed the other females as if urged by sexual desire. This kind of acquired hermaphroditism in aged females has, however, been more fre- quently and carefully attended to as it occurs in Birds than as met with among the Mamma- lia, the change to virilescence in the former being more marked and striking than in the latter, owing to the great difference which gene- rally exists between the plumage of the male and female. || When old female birds live for any considerable period after their ovaries have ceased to produce eggs, they are usually ob- served to assume gradually more or less of the plumage and voice, and sometimes the habits also of the male of their own species. This curious fact, first pointed out by Aristotle U in relation to the domestic fowl, has now been seen to occur in a number of other species of birds, but particularly among the Gallinaceae. It has been in modern times remarked in the common fowl ( P/iasianus gallus ) by Tucker, Butler, and Jameson; in the common pheasant (P. colchicus ) by Hunter and Isidore St. Hilaire ; in the golden pheasant (P. pictus) by Blumenbach and St. Hilaire ; in the silver pheasant (P. ni/chemerus ) by Bechstein and St. Hilaire ; in the turkey ( Meleagris ) by Bechstein ; in the pea-hen ( Pavo ) by Hunter and Jameson ; and in the partridge ( Tetrao perdnx ) by Montagu and Yarrell. Among the Cursores it is mentioned as having occurred in the bustard ( Otis) by Tiedemann, and in the American pelican ( Platalea aiaia) by Catesby. In the order Palmipeds it has been observed by Tiedemann and Rumball in the * Wildungen, Taschenbuch fiir Forst- und Jagd- freunde, s. 17. t Otto's Path. Anat. by South, p. 166, s. 123, n. 18, for list of cases. t Phys. vol. i. § 183, p. 318. § Ueber Virilescenz Thierisch. Koerper ; or British and Foreign Med. Review, vol. vi. p. 77. || It occurs also more frequently among birds than among mammalia, from the former possessing only a single ovary. % " Gallini, cum vicerint gallos, concurrunt ma- resque imitandi subagitare conantur. Attollitur etiam crista ipsis, simul et clunes (uropygium) ; adeo ut jam non facile diagnoscantur an fceminae sint. Quibusdam etiam calcaria parva surrigun- tur." Hist. Animal, lib. ix. cap. 36. HERMAPHRODITISM. 717 domestic and wild duck f Anas boscha ). Among the Scansores it has been seen in the cuckoo ( Cuculus canorus ) by Payraudeau ; and among the Passeres in the cotinga ( Am- pelis ) by Dufresne ; in the chaffinch ( Frin- gilla J and rougequeue ( Motacilla ) by Prevost ; and in the bunting ( Ember iza paradisaa and longicauda ) by Blumenbach. This change of plumage in old female birds commences,according to M.Isidore St.Hilaire,* much sooner in some instances than in others ; it may only begin to show itself several years after the bird has ceased to lay, though depend- ing more or less directly upon this phenomenon, and sometimes it commences immediately after it. The change may be effected in a single season, though in general it is not complete for some years. When it is perfected, the female may display not only the variety of colours, but also the brilliancy of the male plumage, which it sometimes resembles even in its ornamental appendages, as in the acquisition of spurs, and, in the domestic fowls, of the comb and wattles of the cock. The voice of the bird is also very generally changed. Its female habits and in- stinct are likewise often lost ; and, in some in- stances, it has been seen to assume in a great degree those of the male, and has even been observed to attempt coition with other females of its own species f In most of the female birds that have undergone this change, the ovary has been found entirely or partially dege- nerated, though in a few cases the morbid alte- ration is not very marked, eggs having even been present in the organ in one or two in- stances. In general, however, it is greatly diminished in size, or has become altogether atrophied ; but the perfection of the change in the plumage does not seem to bear any direct ratio with the degree of morbid alteration and atrophy in the ovary. That the changes towards the male type, de- scribed as occasionally occurring in old female birds, is directly dependent, not upon their age, but upon the state of the ovaries in them, seems still further proved by similar changes being sometimes observed in these females long previous to the natural cessation of the powers of reproduction, in consequence of their ovaries having become wasted or destroyed by disease. Greve,^ in his Fragments of Comparative Anatomy and Physiology, states that hens whose ovaries are scirrhous crow sometimes like cocks, acquire tail-feathers resembling * Edinburgh Journ. of Philosoph. Science, (1826") p. 308. t Rumball, in Home's Comparative Anatomy, vol. iii. p. 330, states having observed an old duck which had assumed the male plumage, attempt sexual connection with another female. This may perhaps enable us to understand the reputed cases of hermaphroditism in women, who, as related by Mollerus (Tract, de Hermaphr. cap. ii.) and Blan- card, (Collect. Medico-Phys. cent. iii. obs. 80,) after having themselves borne children became ad- dicted to intercourse with other females. Of course we cannot give our credence to the alleged success- ful issue of such intercourse. t Bruchstuccke sur vergleich. Anat. und Phvsiol. s. 45. those of the male, and become furnished with large spurs. The same author mentions also the case of a duck, which, from being previously healthy, suddenly acquired the voice of the male, and on dissection its ovary was found hard, cartilaginous, and in part ossified. Mr. Yarrell, in a paper read before the Royal Society in 1827,* has stated that in a number of instances he had observed young female pheasants with plumage more or less resem- bling the male, and in all of them he found on dissection the ovaries in a very morbid state, and the oviduct diseased throughout its whole length, with its canal obliterated at its upper part. He also shews that a similar effect upon the secondary sexual characters of the female bird is produced by the artificial division and removal of a small portion of their oviduct in the operation of making capons of female poul- try ; and he states that his investigations have led him to believe that in all animals bearing external characters indicative of the sex, these characters will undergo a change and exhibit an appearance intermediate between the perfect male and female, wherever the system is de- prived of the influence of the true sexual organs, whether from original malformation, acquired disease, or artificial obliteration ,f From the frequency with which castration is performed, the effects of the testicles in evol- ving the general sexual peculiarities of the male have been more accurately ascertained than those of the ovaries upon the female consti- tution. These effects vary according to the age at which the removal of the testicles takes place. When an animal is castrated some time before it has reached the term of puberty, the distinctive characters of the male are in general never developed ; and the total absence of these characters, together with the softness and re- laxation of their tissues, the contour of their form, the tone of their voice, and their want of masculine energy and vigour, assimilate them more in appearance and habits to the female than to the male type. If the testicles are removed nearer the period of puberty, or at any time after that term has occurred, and * Phil. Trans, for 1827, part ii. p. 268. t On old or diseased female birds assuming the plumage, &c. of the male, see J. Hunter, Observ. on the An. Econ. p. 75; E. Home, Lect. on Comp. Anat. vol. iii. p. 329; Mauduit, in Encycl. Method. Art. Fuisan, torn. 'ii. p. 3 ; Butter, in Wernerian Soc. Mem. vol. iii. p. 183 ; Schneider's Notes, in his edition of the Emperor Frederick the Second's Treatise " De Arte Venandi cum Avibus;" Tucker's Ornithologia Damnoniensis ; Catesby's Natural History of Carolina, &c. i. t. 1. ; Bechstein, Naturgeschichte d. Deutschlands, bd. ii. § 116; Blumenbach, De anomalis et vitiosis quibusdam nisus formativi aberrationibus, p. 8 ; and Instit. of Physiology, p. 369; Payrandeau, Bull, des Sc. Nat. t. xiii. p. 243 ; Tiedemann, Zoologie, vol. iii. p. 306 ; Geoff. St. Hilaire, Phil. Anat. torn. ii. p. 360 ; Isid. St. Hilaire, Mem. du Mus. d'Hist. Nat. torn. xii. p. 220 ; Annal. des Sc. Nat. t. vii. p. 336, or Edinburgh New Philosophical Journal for 1826, p. 302, with additional cases by Professor Jameson, p. 309 ; Kob, De mutatione sexus, p. 11. Berlin, 1823 ; Yarrell, Phil. Trans, for 1827, p. 268, with a drawing of the diseased ovaries, &c. 718 HERMAPHRODITISM. when the various male sexual peculiarities have been already developed, the effect is seldom so striking; the sexual instincts of the animal, and the energy of character which these in- stincts impart, are certainly more or less com- pletely destroyed, and the tone of the voice is sometimes changed to that of puberty ; but the general male characteristics of form, such as the beard in man, and the horns in the Ru- minantia, most commonly continue to grow. In animals, such as the stag, which possess deciduous horns, the removal of the testicles during the rutting season causes the existing horns to be permanent; and if the operation is performed in an adult animal when out of heat, no new horns in general appear.* In the ox, the effect of castration upon the growth of the horns, even when performed before the time of puberty, is quite remarkable ; for instead of having their development altogether stopped, or their size at least diminished by the opera- tion, as occurs in the ram and stag, the volume of these appendages is even increased by the operation, the horns of the ox being generally larger but less strong than those of the entire bull. Castration in the boar causes, according to Greve,f the tusks to remain small, and pre- vents altogether the replacement of the teeth. This author also states that the same operation on the horse prevents the full development of the neck, renders the teeth smaller and slower in their growth, increases the growth of the hair, and the size of the horny protuberances on the inside of the legs. The prostate gland, he further alleges, as well as the vesiculae se- minales, become augmented as much as a third in their volume in consequence of the operation .J The removal of the testicles both before and after the period of puberty commonly gives rise to another singular effect,- — to an increased deposition of fat over the body, as has already been mentioned in the article Adipose Tissue, and from this circumstance the general form of the body, and in man that of the mammae, is sometimes modified in a degree that in- creases the resemblance to the opposite sex. In the sterile of both sexes in the human sub- ject an unusual corpulency is not uncom- mon, and the same state is often met with in old persons, and particularly in females, after the period of their child-bearing life is past. The nature of the effects produced by the existence and functional activity of the testicles and ovaries upon the development of the se- condary sexual characters of the male and female, may be further illustrated by what occurs in the season of heat to animals such as the deer, sheep, birds, &c. that have peri- odical returns of the sexual propensity. At these periods all the distinctive general characters of the sexes become much more prominently developed, in conjunction with, and apparently in consequence of, the changes which have * Buffon, Hist. Nat. torn. vi. p. 80. t Bruchstuecke zur Vergl. Anat. und Physiol, p. 41. t Loc. cit. p. 45. been ascertained by observation to occur at that time in the relative size and activity of the in- ternal organs of generation. Thus with the return of the season of sexual instinct the dorsal crests and cutaneous ear-lobes of tritons enlarge; in Batrachian Reptiles the spongy inflations of the thumbs become increased in size ; the various species of singing birds re- acquire their vocal powers ; and some, as the cuckoo and quail, appear capable of exercising their voice only at this period of the year. At the pairing season also the plumage of birds becomes brighter in tint, and in some instances is in other respects considerably changed, as in the male ruff ( Tringa pugnax), who then reassumes the tuft of feathers upon his head and neck, and the red tubercles upon his face that had fallen oft' during the moulting, and thus left him more nearly allied in appearance to the female during the winter. In reference to this subject, it appears to us interesting to remark, that in certain birds, as in the different species of the genus Fringilla, the male pre- sents in winter a plumage very similar to that of the female,* and in the present inquiry it is important to connect this fact with the very diminutive size and inactive condition of the testicles of these birds at that season. (See Aves.) From the remarks that we have now made upon the influence of the ovaries and testicles in developing the general sexual peculiarities of the female and male, it will be easy to con- ceive that when, in cases of malformation of the external genital organs giving rise to the idea of hermaphroditism, there is at the same time, as sometimes happens, a simultaneous want of development in the internal organs of reproduction, particularly in the ovaries and testicles, the general physical and moral pecu- liarities distinctive of the sex of the individual may be equally deficient, or have a tendency even to approach in more or fewer of their points to those of the opposite sexual type. In this way we may, it is obvious, have general or constitutional hermaphroditic characters, if they may be so termed, added to those al- ready existing in the special organs of gene- ration, and rendering more difficult and com- plicated the determination of the true sex of the malformed individual. Some cases of spu- rious hermaphroditism in the male published by Sir E. Homef may serve to illustrate this remark. A marine soldier, aged twenty-three, was admitted a patient into the Royal Naval Hos- pital at Plymouth. He had been there only a few days, when a suspicion arose of his being a woman, which induced Sir Everard to ex- amine into the circumstances. He proved to have no beard; his breasts were fully as large as those of a woman at that age ; he was in- clined to be corpulent; his skin was uncom- monly soft for a man ; his hands were fat and short, and his thighs and legs very much like those of a woman : the quantity of fat upon * Stark's Elements of Nat. Hist, vol.i. p. 243. t Comp. Anat. vol. iii. p. 320. HERMAPHRODITISM. 719 the os pubis resembled the mons veneris ; and in addition he was weak in his intellect, and deficient in bodily strength. The external genital organs shewed him to be a male, but the penis was unusually small, as well as short, and not liable to erections ; the testicles were not larger in size than they commonly are in the foetal state ; and he had never felt any pas- sion for the opposite sex. The following cases by the same author strongly illustrate this subject.* In a family of three children residing near Modbury in De- vonshire, the second, a daughter, was a well- formed female, the eldest and youngest were both malformed males. The eldest was thir- teen years of age. His mons veneris was loaded with fat ; no penis could be said to be present, but there was a prseputium a sixth of an inch long, and under it the meatus urina- rius, but no vagina. There was an imperfect scrotum with a smooth surface, there being no raphe" in the middle, but, in its place, an in- dented line ; it contained two testicles, of the size that they are met with in the foetus. His breasts were as large as those of a fat woman. He was four feet high, and of an uncommon bulk, his body round the waist being equal to that of a fat man, and his thighs and legs in proportion. He was very dull and heavy, and almost an idiot, but could walk and talk ; he began to walk when a year and a half old. The younger brother was six years old, and uncommonly fat and large for his age. He was more an idiot than the other, not having sense enough to learn to walk although his limbs were not defective. A case in a similar manner confirmatory of the preceding remarks is mentioned by Itard de Riez.f A young man, aged twenty-three, had no testes in the scrotum, a very small penis, not capable of erection, and a divided scrotum. He was in stature below the middle size. His skin was soft, smooth, and entirely free from hair, the place of the beard being supplied by a slight down. The voice was hoarse; the muscles were not well marked ; the form of the chest resembled that of the female, and the pelvis was extremely broad and large. The intellectual faculties were very dull, and the sexual appetite was entirely wanting. Renauldin, also, in the same work,]: has re- corded another case in point. In a soldier of twenty-four years of age, whose genital organs were extremely undeveloped, his penis being only of the size of a small tubercle, and his testicles not larger than small nuts, the pelvis was broad; the chest narrow; the face and body in general were not covered with hair, with the exception of a small quantity upon the pubis ; the voice was feminine, and the mammary glands were as perfectly developed as in the adult female. The body of this in- dividual was rather lean than otherwise. The * lb. p. 320-21. t Memoires de la Soiicte Med. d'Emnlation, torn. iii. p. 293-5. t Tom. i. p. 241. mammae had begun to enlarge when his body attained to its full stature at sixteen years of age. He had all the habits and sexual desires of the male sex. In quadrupeds as in man, when the tes- ticles or ovaries are imperfectly formed, the secondary sexual peculiarities are frequently so defectively evolved as to offer a kind of her- maphroditic or neutral type in the general con- figuration and characters of the animal. Thus, the free-martin does not present an exact analogy in form either with the bull or cow, but exhibits a set of characters intermediate between both, and more nearly resembling those of the ox and of the spayed heifer. In size it resembles the castrated male and spayed female, being considerably larger than either the bull or the cow, and having horns very similar to those of the ox. Its bellow is simi- lar to that of the ox, being more analogous to that of the cow than of the bull. Its flesh, like that of the ox and spayed heifer, is gene- rally much finer in its fibre than the flesh of either the bull or cow, and is supposed to exceed even that of the ox and heifer in deli- cacy of flavour.* The consideration of the various facts that we have now stated inclines us to believe that the natural history characters of any species of animal are certainly not to be sought for solely either in the system of the male or in that of the female ; but, as Mr. Hunter pointed out, they are to be found in those properties that are common to bolh sexes, and which we have occasionally seen combined together by nature upon the bodies of an unnatural her- maphrodite; or evolved from the interference of art, upon a castrated male or spayed female. In assuming at the age of puberty the distinc- tive secondary peculiarities of his sex, the male, as far as regards these secondary pecu- liarities, evidently passes into a higher degree of development than the female, and leaves her more in possession of those characters that are common to the young of both sexes, and which he himself never loses, when his tes- ticles are early removed. These and other facts connected with the evolution of both the primary and secondary peculiarities of the sexes further appear to us to shew that, phy- siologically at least, we ought to consider the male type of organization to be the more per- fect as respects the individual, and the female the more perfect as respects the species. Hence we find that, when females are mal- formed in the sexual parts so as to resemble the male, the malformation is almost always one of excessive development, as enlargement of the clitoris, union of the labia, &c. ; and, on the other hand, when the male organs are malformed in such a manner as to simulate the female, the abnormal appearance is generally capable of being traced to a defect of deve- lopment, such as the want of closure of the perinseal fissure, and of the inferior part of the urethra, diminutive size of the penis, retention * Hunter's Obs. on the An. Econ. p. 60. 720 HERMAPHRODITISM. of the testicles in the abdomen, &c. In the same way, when the female assumes the secon- dary characters of the male, it is either, first, when by original malformation its own ovaries and sexual organs are so defective in structure as not to be capable of taking a part in the function of reproduction, and of exercising that influence over the general organization which this faculty imparts to them; or, secondly, when in the course of age the ovaries have ceased to be capable of performing the action allotted to them in the reproductive process. In both of these cases we observe the powers of the female organization, now that its capabilities of performing its particular office in the continuation of the species are wanting or lost, expend themselves in perfecting its own individual system, and hence the ani- mal gradually assumes more or fewer of those secondary sexual characters that belong to the male. We do not consider it subversive of the pre- ceding view to qualify it with the two follow- ing admissions, — 1st, that, owing to the ener- gies of the female system being so strongly and constantly directed towards the reproduc- tive organs, and the accomplishment of those important functions which these organs have to perform in the economy of the species, the general characters of the species may be de- veloped in her body in a degree less than they otherwise would be, or than actually consti- tutes the proper standard of the species ; and, 2dly, in consequence of the peculiarities of the sexual functions of the female, some of the individual organs of her system, as the mamma?, are evolved in a degree greater than is consonant with the standard characters of the species. At the same time we would here remark that the occasional enlarged condition of the mamma) in hermaphrodites in whom the male sexual type of structure predominates, (as in the examples of spurious male herma- phrodites that have been quoted from Sir E. Home, and in other instances mentioned by Renauldin, Julien, Petit, Rullier, and others in the human subject, as well as in numerous cases among hermaphrodite quadrupeds,) would almost seem to shew that the full development of the mammary glands is a character proper to the species in general, rather than one pecu- liar to the female system alone. In males, also, who are perfect in their reproductive organs and functions, the mamma? are some- times observed to be developed in so complete a manner as to be capable of secreting milk, forming what may be regarded as one of the slightest approaches towards hermaphroditic malformation in the male organization;* and * The secretion of milk in the mammary glands of the male is occasionally observed amongst our domestic quadrupeds. See Gurlt's Pathologischen Anatomie der Haus-Saugthiere, Bd. ii. s. 188 ; Blumenbach in the Hanoversich Magazin for 1787 ; and Home in Comp. Anat. iii. p. 328. Among the recorded instances and observations upon it in man we may refer to Paullini, Cynographia, p. 52 ; Schacher, De Lacte Virorum et Virginum, Leipz. the mammae of the infants of both sexes not unfrequently contain a lactiform fluid at birth. In some instances of hermaphroditic mal- formation the total form and configuration of the body have been alleged to present not only a general tendency towards the physical se- condary characters of the opposite sex, or to exhibit in a permanent state the neutral con- dition existing before puberty, but different individual parts of it have been occasionally conceived to be developed after a different sexual type. Thus, for instance, we have al- ready mentioned in regard to Hubert Jeau Pierre, that the upper half of the body of this individual seemed formed after the female, and the lower half after the male type, the larynx and mammae being quite feminine, the face shewing no appearance of beard, and the arms being delicate and finely rounded, while the pelvis was narrow, and the thighs were marked and angled as in man. In a case described by Schneider,* the reverse held true, the bust being male with a strong beard and large thorax, and the pelvis being large and distinctly female. A more mixed combination of the secondary sexual characters has been already described as existing in the cases detailed by Ricco, Mayer, Arnaud, Bouillaud, &c. One side of the body has been sometimes observed to be apparently formed in one or more of its parts on a sexual type different from that of the same parts on the opposite side. Girald, in his Topography of Ireland,f mentions a reputed female, who had the right side of the face bearded like that of a man, and the left smooth like that of a woman. Mr. King J has described an interesting in- stance of hermaphroditic malformation in an individual whose general character was mas- culine, but with the pelvis large and wide; the left testicle only had descended into the groin, and the mamma of this side was small comparatively to that of the opposite or right side. In a hind mentioned by Mr. Hay,§ and which, he believed, had never produced any young, one of the ovaries on dissection after death was found to be scirrhous. The animal had one horn resembling that of a three years- old stag on the same side with the diseased ovary ; there was no horn on the opposite side. Bomare|| has given a similar case in the same 1742; Sinnibaldus, Geneanthrop. torn. iv. p. 456; Alex. Benedictus, Anatom. Corp. Hum. lib. iii. p. 595 ; Winslow, Anatomy, vol. ii. p. 214 ; Deusing, De Lacte, p. 327 ; Kyper, Anthropo- logia, lib. i. p. 490; Buffon, Hist. Nat. torn. ii. p. 543 ; Bishop of Cork, Phil. Trans, vol. xli. p. 813 ; Humboldt, Personal Narrative, vol. iii. p. 57 ; Franklin, First Expedition to the Polar Seas, (London, 1823.) p. 157. * Kopp's Jahrbuch der Staatsarzneikunde, Bd. x. s. 134. t Topog. Hiberniae, in Camden's Angl.&c. (1603), part ii. p. 724. t London Med. Repository for 1820, vol. xiii. p. 87. 4 Linnaean Transactions, vol. iii. p. 356. [| Journ. de Phys. torn. vi. p. 506. HERMAPHRODITISM. 721 animal, where a single horn was present, situ- ated also on the same side with the diseased and degenerated ovary ; and Russell * states, as the result of his experiments on castration in the deer, that when he removed one testicle only from the animal, the horn on the opposite side was the more completely developed of the two. Azaraf observed in two birds the right side of the tail to possess the characters of the male, and the left those of the female. In the hermaphroditic lobster previously al- luded to as described by Nicholls, the general external configuration of the body was, like that of the sexual organs, perfectly female on one side, and perfectly male on the other. It is principally, however, among herma- phroditic insects that a difference of sexual type in the general conformation of the oppo- site sides of the body, and of its individual parts, has been observed ; and this malforma- tion is the more striking and easy of obser- vation in this class of animals, on account of the great differences in colour, size, and form respectively presented by the antenna;, wings, and other pai ts of the body of the males and females of the same species. Lateral hermaphroditism of the body in In- sects has been most frequently observed by Entomologists amongst the class Lepidoptera. It has now been remarked in the following species: — in the Argynnis papliia, Lycana alexis, Saturnia pyri, Endromis versicolor, and Hurpya vinula (Ochsenheimer) ; in the Gas- trophaga medicaginis and Lycana adonis (Rudolphi) ; in the Liparis dispur (Schaefer, Ochsenheimer, and Rudolphi); in the Sa- turnia Carpini (Capieux, Ochsenheimer, and Rudolphi); in iheOrastrophagaquercifblia (Hett- linger and Rudolphi); in the Gastrophaga pini (Scopoli); in the Gastrophaga cratagi (Esper); in the Sphinx convolvuli (Ernst); Sphinx populi (Fischer and Westwood) ; Papilio polycaon (Macleay); Polyonimatus alexis (Entomolog. Mag. vol. iii. p. 304); Bombyx castrensis (Duval) ; in the Argynnis paphia (Allis) ; in the Vanessa atalanta (Schrank and Germar); and in the Vanessa antiopha and Deilephila euphorbia (Germar). King and Germar have recorded two instances of it among the Cole- optera, the former in the Lucanus cervus, and the latter in the Melolontha vulgaris ; and Mr. Westwood mentions a third case in the large water-beetle ( Dyticus marginalis ), as con- tained in Mr. Hope's collection, and has seen a fourth in the stag-beetle (Lucanus cervus ). Out of twenty-nine recorded cases of lateral hermaphroditism in Insects, in which the sexual characters of each side are distinctly specified, we find that in seventeen instances the right side was male, and in twelve female. Burmeister alleges that in by far the majority of cases the right side is male, and the left female, — a statement in which Meckel co- incides, while Westwood maintains the reverse. The cases we have ourselves collected are cer- tainly numerically in favour of the former * Economy of Nature in Glandular Diseases, t Kob's Dissert, rle Mutatione Sexus, p. 19. VOL. II. opinion, but the data are as yet so few, and the difference so trifling, as not to warrant us to come to any decided conclusion on this point. In some instances we find among insects an imperfect lateral hermaphroditism consisting of some parts of one side, as of one or more of the wings, palpi, or antennse being formed according to a different sexual type from the same parts of the opposite side, and from the general body of the animal. Thus in the Melitoea described and dissected by Klug (see Lateral Herma- phroditism ) the general form of the insect was male, but the left eye, palpus, antenna, and left sexual fang were smaller than in individuals belonging to this sex ; the left antenna was annulated with white and yellow at the apex, while the right was of one colour; the general form of the abdomen was male but somewhat thick, and the wings were all equal and male. In a Pontia duplidice mentioned by Rudol- phi, and which in its general external characters was female, the right anterior wing was formed after the male type, and the sexual organs also resembled those of the male. Ochsenheimer mentions one Gastrophaga qucrcus with the body, and the antenna? and wings on the left side female, and the right wings male ; and a second with the body and the right side female, and the left side and two an- tennae male, the latter being brown and pecti- nated. In this imperfect variety of lateral herma- phroditism, the malformed wing, antenna, or palpus is sometimes formed after one sexual type and coloured after another. In a male Melitwa pha-be noticed by Germar, the right wings and antenna were female in regard to size, but male in respect to colouring and markings. In a female Deilephila galii, he found the left antenna and palpus of the small size of the male, but agreeing in colouring and markings with the corresponding female parts on the right side. In a Pontia cardamincs, which was male in all its other characters, Ochsenheimer observed the right superior wing marked as in the female, and he mentions another individual of the same species which had a female form with some male colours. In another variety of insect hermaphroditism the sexual difference is sometimes, as we have already noticed in regard to the human subject, expressed not by a lateral, but by a longitudinal sexual antagonism, or, in other words, the anterior and posterior parts of the body are formed after the two opposite sexual types. Thus in a Satwnia carpini described by Ochsenheimer, the antennae were male, the superior wings male in form, but coloured as in the female, and the posterior wings, with the exception of a reddish brown spot upon the left, were, with the body and other parts, female. Lastly, in a third variety of external hermaphro- ditic conformation in Insects, we find the char- acters of the two sexes mixed up and crossed in different irregular combinations upon the body of the same individual. In a Gastrophaga castrensis described by Rudolphi, and where the male type predominated, with a tendency, 3 8 722 HERMAPHRODITISM. however, in all parts to the female form, the right antenna and the wings on the opposite or left side were distinctly female, while the left antenna and right wings were entirely male, the latter being only somewhat larger than in male insects, and the colours brighter than in the female. In a Bombyx castremis alluded to by Westwood, the wings on the right side, and the antennre and abdomen of the left, were those of a male, while the left winsr, right an- tenna;, and right side of the abdomen were those of a female. GENERAL SUMMARY WITH REGARD TO THE NATURE OF HERMAPHRODITIC MALFORMA- TIONS. 1 . Of the varieties of spurious hermaphro- ditism.— On some of these varieties it is un- necessary for us to dwell here. The first species of spurious male hermaphroditism, or that arising from extroversion of the urinary bladder, is elaborately discussed elsewhere (see Bladder); and two others, namely, the second female species consisting of prolapsus of the uterus, and the second male consisting of an adhesion of the penis to the scrotum, seem both referable to the head rather of disease than of original malformation. This latter indeed ap- pears in all probability only an effect or result of adhesive inflammatory action in the affected parts during embryonic or foetal life. Both of the two remaining forms of spurious hermaphroditism, — viz. those consisting of hypospadic fissure of the urethra, scrotum, and peiinaeum in the male, and of abnormal magnitude of the clitoris in the female, — seem readily explicable upon the doc- trine of arrestment and anormality in the deve- lopment of the malformed parts. We have already described at sufficient length the process of development of the dif- ferent copulative organs, and have shewn that those various degrees of hypospadic malforma- tion which constitute the common form of spurious hermaphroditism in the male, may be traced to arrestment of this process at various periods or stages of its progress. And we may here remark that the earlier this arrestment occurs, the distinction of the true sexual type of the malformed organs will always be the less marked, because the younger the embryo, and, on a similar principle, the lower we descend in the scale of animal existence, we find the dif- ferences between the organs of the two sexes proportionally the less pronounced, until at last we arrive at that primitive type in which these organs present altogether a common, neu- tral,'or indeterminate character. We have also already shewn that at a certain early stage of the development of the female organs, the female clitoris holds the same, or nearly the same relatively larger size to the whole embryo as the penis of the male, and that so far we may consider the occasional occurrence of spurious hermaphroditism from magnitude of the clitoris, and its resemblance in this respect to the male organ, as a perma- nent condition of a type of embryonic structure that is normally of a temporary or transitory existence only. But besides this permanence of the embryonic type of the clitoris, we must farther, in all the more complete instances of spurious female hermaphroditism, admit an excess of development in the malformed external sexual parts, and more particularly in the line of the median reunion of the two primitive lateral halves or divisions of these parts. In this way the vagina (a remnant in the female of the primitive perineal cleft or fissure) is often in such cases more or less con- tracted and closed, so much so indeed in some instances as to leave only, as in the male, a small canal common to the genital and urinary passages. If the median junction is extended still farther, this canal comes also to imitate the male urethra in this respect, that it is united or shut up below in such a way as to be carried onward to a greater or less length, and in a more or less perfect condition along the under surface of the enlarged clitoris ; and occasion- ally the male type of structure is still more completely repeated in the female organization by the median reunion of the two labia, giving the appearance of theunited scrotum and closed perinaum of the opposite sex. If we divide the whole sexual apparatus of the male and female into three corresponding transverse spheres or segments, — the first or deep parts including the testicles and ovaries, the second or median comprehending the male seminal canals and prostate gland, and the female oviducts and uterus, and the third or external embracing the copulating organs of the two sexes, — we shall find that, relatively speaking, the deep and the external spheres are naturally most developed in the male economy, while the median, comprising the uterus, (the principal and most active organ in the female reproductive system,) is developed in the greatest degree in that sex. In malformed females presenting a spurious hermaphroditic character, this important portion of the female sexual organization is, in general, either itself in some respects malformed, or, from the structure of the other parts of the sexual appa- ratus being imperfect, its specific importance in the economy is cancelled, and therefore the energy of development takes the same direction as in the male, being expended upon the more complete evolution of the organs of the external and deep spheres. Hence the greater size of the clitoris, and the greater development which we have just now pointed out, in the median line of reunion of the external sexual parts ; and hence also the occasional though rare occurrence, in the same cases, of the descent of the ovaries through the inguinal rings into the labia, — an anomaly that certainly consists in a true excess of development, and which we cannot but regard as interesting, both in this respect, and as affording a new point of analogy between these organs themselves and the male testicles. There is another and equally interesting point of vie\v in which we may look upon this sub- ject. Not only are the forms of spurious her- maphroditism which we have been considering, capable of being traced backward to certain tran- sitory types of sexual structure in the embryos HERMAPHRODITISM. 723 of those animal species in which the malfor- mations in question occur, but they may be shewn also to present in their abnormal states repe- titions of some of the normal and permanent conditions of the sexual organs in various species of animal beings placed lower in the scale of life. Thus the occasionally imperforate penis of the male hermaphrodite lias been supposed to have an analogue in the naturally solid penis of some of the species of the genera Doridium and Hyalcea* Its more or less grooved or hy- pospadie condition is similar to the natural type of the same part in some hermaphrodite Mollusca, as in the Planorbis and Murex :f in its occasional diminutive size it approaches the general smallness of the partially fissured penis of most birds and reptiles ; and we find it in the Rodentia and Marsupiata tied down by a short prepuce in a way analogous to what is seen in some cases of severe hypospadias. In the sloth ( Uradypus tridactylus) the penis is small and grooved in its lower surface, and has the urethra opening at its base ;J and in several of the male Rodentia the scrotum is also cleft, and has its two opposed surfaces smooth, humid, and free of hair, as in most cases of hypospadic hermaphroditism in man. In Ophidian and in most Saurian Reptiles, the male seminal ducts open at once externally, as in some male hermaphrodites, at the root of the fissured penis. The fact of the testicle some time remaining, in cases of hermaphrodite formation in the human subject, within the cavity of the ab- domen, presents to us in a permanent state their original but changeable position in the early foetus, and at the same time affords a repetition of their normal situation, in almost all the lower tribes of animals, and in the Cetacea, Amphibia, Edentata, and some Pa- chydermata, as the Cape Marmot (Hyrux ) and Elephant, among the Mammalia. The malformed clitoris in instances of spurious hermaphroditism assumes also, in its abnormal state, types of structure that we find as the normal condition of the organ in various inferior animals. Thus in female Cetacea and Rodentia, and in the animals included in Cuvier's order of Carnassiers, but more par- ticularly among the Quadrumana, the clitoris retains as its permanent normal type that relatively larger size which we observe in the early foetus, and in female hermaphrodites in the human subject : and further, as is some- times seen in such malformed individuals, the clitoris becomes partially traversed by the urethra, as in the Ostrich, Emu,§ and Ant- eater ;|| and in the Loris (as we have noticed in a preceding page) and Maki, it is completely enclosed, like that of the male, in the body of * Burdach's Physiologie, Bd. i. § 132, p. 231. t Tiedemann's Zeitschrift fuer Physiologie, Bd, i. s. 15, or Cuvier, Anat. Comp. torn. v. p. 182. \ Meckel, Beitrasge zur vergleiclicnden Anatomic, Bd. ii. cap. i. p. 125. j Cuvier, Anat. Comp. t. v. p. 129. || Meckel, Archiv. fuer die Physiologie, Bd. v. ». 66. the organ, forming a continuous and perfect canal through it. We may here further observe, (though the illustrations should more properly belong to the next section,) that in cases of true hermaphro- ditism also in man and quadrupeds, as well as in the above spurious varieties, there may be often traced in some portions of the abnormal structures a sexual type bearing a greater or less analogy to the corresponding parts of those inferior animals that are naturally andro- gynous. Thus, in instances of true hermaphro- ditism, the orifices of the sexual ducts or passages occasionally open into a common cavity, as is normally the case in some species' of Doridium, Helix, and other Mollusca ; or the female oviducts or Fallopian tubes, and the male vasa deferentia, run closely alongside of each other without any communication between their canals, as in the Alj/psia and most Gas- teropoda. Indeed the occasional co-existence even of both testicles and ovaries in individuals among the higher animals would be only a repetition of, or retrogression to, the normal sexual type of those genera of animals that we have just named, and of the Planaria, Ces- toidea, and other natural hermaphrodites. In this way we see, that, (as in many other monstrosities,) the several varieties of malfor- mation in the sexual organs occurring in spurious human hermaphroditism do not con- sist of the substitution of an entirely new and anomalous type of structure, but are only repetitions of certain types of the same organs that are to be met with both in the human foetus and in the inferior orders of animal beings. The investigation of the whole subject shews us in reference to the sexual organs, what is equally true in regard to all the other organs of the body, — that their different stages of development in the embryos of man and of the higher orders of animals cor- respond to different stages of their deve- lopment in the series of animal beings taken as a whole ; so that here, as elsewhere, the facts of Comparative Anatomy are repro- duced in those of Embryology, and both are repeated to us by nature on a magnified scale in the anatomy of the malformations of the part, — a circumstance amply testifying to the intimate relations which subsist between Com- parative Anatomy, the anatomy of Embryonic Development, and that of Monstrosities. Indeed proportionally as our knowledge of malformations has increased, it has shewn us only the more strongly that the laws of forma- tion and malformation, — of normal and abnor- mal development, are the same, or at least that they differ much more in degree than in essence, and that the study of each is calculated recipro- cally to illustrate and to be illustrated by the study of the other. 2. Nature of true hermaphroditic malfor- mations.— Of the nature of local malforma- tions by duplicity, we at present possess much less precise knowledge than of those of simple defect or simple excess of development ; but there are certain facts ascertained with regard 3 » 2 724 HERMAPHRODITISM. to the formation of the sexual organs, which may enable us to make an approach at least to accurate ideas of the character and origin of those anormalities that constitute the several varieties of true hermaphroditism. These facts relate to the interesting subject of the unity of structure which is manifested in the correspond- ing male and female reproductive organs of the human subject, and of other species of bisexual animals. By several of the Greek, Roman, and Ara- bian physiologists,* the respective organiza- tions of the two sexes were considered as in some degree typical of one another, the female being regarded as an inverted male, with the testicles and penis turned inwards to form the ovaries and uterus. This doctrine of analogy between the male and female sexual organs has, with various modifications, been very ge- nerally admitted by modern physiologists, and in some of its bearings it has been made, more particularly of late years, the subject of consi- derable discussion. The testicles are still re- garded as organs which correspond with the ovaries in their original situation, in their vas- cular and nervous connections, and in their re- lative sexual functions. The recent progress of the anatomy of the development of the em- bryo has also shewn that the two organs cor- respond in their primitive origin. It is now well ascertained that the large masses occupy- ing each side of the abdomen of the embryo at an early stage of development, and which Rathke has named the Wolffian bodies after their illustrious discoverer, form, in Birds and Mammalia at least, the primordial matrices upon which the urinary and genital organs are developed. On the inner side of each of these matrices a small body is early developed, which seems to become afterwards either a testicle or an ovary, according to the particular ulterior sexual type which the embryo assumes. In further following up the analogy of struc- ture between the organs of the two sexes, the vasa deferentia of the male are generally com- pared to the Fallopian tubes of the female, the scrotum to the external labia, the body of the penis to the clitoris, and its corpus spon- giosum, or, according to others, its prepuce, is regarded as corresponding in type with the female nymphje. A considerable dif- ference of opinion, however, still prevails as to the prototype of the female uterus in the male system. Some anatomists, as Burdach, Steghlener, and Blainville, regard the uterus and male vesiculae seminales as corresponding parts ; while others, as Meckel, Cams, Schmidt, Ackermann, and Serres, compare the uterus to the male prostate. A sufficient number of facts seems still wanting to determine the accu- racy and justness of either of these analogies. There are instances of malformation on record which appear to favour both opinions, and there are other cases which almost incline us to be- * Aristotle, Hist. An. lib. i. 17. Galen, De Semine, lib. ii. & De Usu Partium, c. i. Rhases, De Re Medica, lih. i. cap. 26. Avicenna, De Membris Ge- nerut. lib. i:i. 21, &c. lieve that the vesicula? seminales correspond to the fundus or body of the uterus in the human subject, and to the cornua uteri in quadrupeds ; while the prostate represents in the male struc- ture the lower portion or cervix of the same organ. The phenomena of the development of the reproductive organs in the embryo will, when more fully investigated, probably serve to clear up this question. M. Geoffiroy St. Hilaire has propounded views of the analogy of the male and female organs in some respects different from the above. He divides the uterus of the human subject into the body and the upper part or fundus, the latter corresponding to what constitutes the cornua uteri in the human embryo, and in adult quadrupeds. Further, believing that in the determination of all analogies in type and structure between different organs, the origin and course of the bloodvessels supplying the part ought to be our principal criterion, he has been led, by the study of the distribution of the branches of the hypogastric arteries, to consider the body of the uterus and the vesicula? semi- nales as repetitions of each other in the two sexes ; and, contraiy to the opinion of most anatomists, he conceives that the male vasa deferentia strictly correspond with the fundus or cornua uteri, and that the epididymis repre- sents a coiled-up Fallopian tube, or in other words that the Fallopian tube is an unrolled epididymis. M St. Hilaire has offered the following table to shew what he conceives to be analogous organs in the two sexes : — * In the male. Testicle = Epididymis — Vas deferens. = Vesicula seminalis = Sheath of the penis = Penis = In the female. Ovary Fallopian tube Cornu of the uterus Body of the uterus. Vagina Clitoris In tracing out the analogies between the male and female parts, the mode in which we ought to consider the female vagina has given rise to some diversity of opinion. From the above table it appears that M. St. Hilaire con- siders it to be represented in the male organiza- tion by the sheath of the penis, but we are cer- tainly inclined to view it in a different light, and to regard it as a part in so far peculiar to the female, that it consists of a permanent condition of that urino-genital perineal fissure that we have already described as existing at a certain period in the embryos of both sexes, and which is latterly shut up in the male, or, speaking more accurately, it is contracted into what forms the pelvic portion of the male urethra. If this were a fit opportunity for following out the consideration of the unity of type be- tween the male and female reproductive organs, it would be easy to shew the justness of those greater analogies that we have mentioned, by pointing out other numerous minor, but still strong points of correspondence manifested in * Phil. Anat. torn. i. (1822,) p. 471. HERMAPHRODITISM. 72* the abnormal conditions and localities of the ovaries and testicles in ihe higher animals, and in their conformity of structure in some of the lower. Thus among Insects, in the genus Li- bellula the long cylindrical testes of the males correspond with the long-shaped ovaries of the females ; in the Locusta and Gryllotalpa, there are ramose bunched testicles with analo- gous fasciculated ovaries ; in the Lumellicornia we find compound radiating and united testes, with similar radiating and united ovaries ; and sometimes, as in the genera Melolontfia and Tric/uus,lhe number of the single bodies in the testicles corresponds with the number of the oviducts.* We have already, when considering spurious hermaphroditism in the female, mentioned several facts illustrative of the analogical pe- culiarities in structure between the male penis and female clitoris in some species of animals ; and Burmeister.f who regards the ovipositors and stings of female insects as corresponding to the clitoris in the female Vertebrata, has pointed out a remarkable conformity of struc- tural type between its valves and those of the penis of the male of the same species. Some organs that are, as far as regards their functions, peculiar and essential to one sex only, are nevertheless found to be repeated in the opposite sex in the form of an analogous rudimentary type of structure. Thus, in the male we may observe the unity of sexual struc- ture maintained in the presence of the rudi- ments of the mammary gland, which is func- tionally an organ of the female system only. In the human subject, and in animals whose females have pectoral mamma:, these organs occupy the same position in the male; while in those species of quadrupeds in which they are placed in the inguinal region, we find them in the corresponding males forming the scrotum or bags for containing the testicles. Hence, as we have already seen, the testicles, in cases of mal- formation in these animals, are often laid upon or imbedded in the udder. In the same way in the Marsupiata, the bone which the female has for supporting the marsupium is repeated in the organization of the male, although in the latter we cannot conceive it to serve any possible use.J: In the female also we observe in some points a similar disposition to the rudimentary repe- tition of parts that are essential or peculiar only to the male organization, as in the repeti- tion in the clitoris of some female Rodentia, of the penis-bone of the male, and in the forma- tion of rudimentary forms of those processes of peritoneum which constitute the tunicse vaginales. We are ourselves inclined also to regard the common crescentic form of the hy- men of the human female in the same light,§ * Burmeister's Entomology, § 154. p. 222. t Loc. cit. % Home's Lect. on Comp. Anat. vol. ii. pi. v. § Burdach ( Phys. §137,) considers the small cutaneous fold situated at the orifices of the vasa deferentia, and Stiebel the membrane placed at the extremity of the urethra (Meckel's Archiv. fur Physiol. J5d. viii. s. 207.) as the analogue in the male for the female hymen. and to consider it merely as an abortive attempt at that closure of the perinseal fissure which we have already described as effected at an early period in the male embryo — an opinion in which we conceive we are borne out both by the history of the' development and the study of the malformations of the external sexual parts in the female. M. Isidore St. Hilaire read, in 1833, to the French Academy a memoir,* in which, follow- ing up the doctrine of his father with regard to the determination and distinction of the type of parts by the particular vessels distributed to thern, he endeavoured to shew some new points of analogy between the male and female organs, and to develop new views with regard to the origin and particular varieties of herma- phroditic malformations. With Burdach, he divides the whole reproductive apparatus of either sex into three transverse spheres and into six portions or segments in all, or three on each side, viz., 1 and 2, the deep organs, in- cluding the male testicles and female ovaries ; 2 and 3, the middle organs, or male prostate and vesiculae seminales, and female uterus ; 3 and 4, the external organs, comprehending the penis and scrotum of the male, and the clitoris and vulva of the female. Each of these portions or segments is, M. St. Hilaire points out, supplied by an arterial trunk peculiar to itself, and the corresponding organs of the male and female by corresponding arterial branches, as the deep organs of both sexes by the two spermatics, the middle by branches of the two hypogastrics, and the external by some other hypogastric branches, and by the external pu- dics. This circumstance, he conceives, renders all the segments in a certain degree independ- ent of the others, both as regards their develop- ment and existence, and allows of the occa- sional evolution of any one or more of them on a type of sexual structure, different from that upon which the others are formed in the same individual. Though assuredly we cannot subscribe to the speculations of the elder St. Hilaire, that the development in the embryo of male testi- cles or female ovaries, and consequently the whole determination of the sex, is originally re- gulated by the mere relative angle at which the first two branches of the spermatic arteries come off", and the kind of course which they follow,! (more particularly as it is admitted by most physiologists that the bloodvessels grow, not from their larger trunks or branches towards their smaller, but from their capillary extremi- ties towards their larger branches,) yet we believe that the doctrine of the comparative independence of the different segments of the * Arch. Gen. de Med. (1833) torn. i. p. 306. t Anat. Phil. torn. i. p. 359. . . " L'ordre de variations des sexes tient a la position d'un artere. . . Le plus on le moins d'ecarlement des deux branches spermatiques motive effective- ment cette preference. Qtieles deux branches de l'artere spermatique descendent parallolement et de compagnie, cette circonstance, je le repete, cette circonstance donne le sexe male ; qu'clles s'ecar- tcnt a leur point de partage, nous avons le sexe fc- mcllc." 726 HERMAPHRODITISM. reproductive organs pointed out by the son is in its general principles correct. At the same time we would here remark that we conceive the doctrine would have been founded more on truth if the influence of the nervous branches supplying the different reproductive organs had been taken into account along with that of their arterial vessels, because, as we shall point out when speaking of the causes of her- maphroditism, there appears to be some con- nection between the state of the nervous sys- tem and the degree or condition of sexual de- velopment. The consideration of the preceding ana- logies in structure between the male and female organs is interesting in itself, and, as far as relates to our present subject, important in this respect, that it enables us in some degree to understand how it happens that, without any actual monstrous duplicity, we should some- times find, in an organization essentially male, one or more of the genital organs absent and replaced by an imperfect or neutral organ, or by the corresponding organ of the opposite sex, and vice versa ; inasmuch as it shews us that the moulds in which the analogous organs of the two sexes are formed are originally the same. Hence there is no difficulty in con- ceiving that, in the body of the same individual, the primitive structural elements of these parts should occasionally, in one or more points or segments, take on, in the process of development, a different sexual type from that which they assume at other points. Indeed some physi- ologists, as we shall immediately see, deny that the most complete hermaphroditic malfor- mations ever consist of anything except such a want of conformity between the sexual type of different portions of the reproductive appa- ratus. If each of the six segments (and we believe that their number might be shewn to be really greater than this,) is thus an independent cen- tre of development in the formation of the sexual apparatus, and is consequently liable also in abnormal cases to have its own parti- cular malformations, and to assume, either alone or along with some of the other seg- ments, a sexual type different from the re- mainder, it is evident that we may have as many varieties of true hermaphroditism, with- out any real duplicity, as it is possible to con- ceive differences of arrangements among these six segments. Again, however, one or more of these segments may preserve from a deve- lopment its original indeterminate or neutral sexual type, while the others are variously formed either upon one or upon both sexual types ; or one or more of the segments may, by a true malformation by duplicity, have evolved within them the corresponding organs of the two sexes ; and if we consider the dif- ferent arrangements of double and single sexual parts that might thus occur in the six separate segments, we may gain some idea of the great diversities of structure in the sexual parts that are liable to be met with in instances of true hermaphroditism. The above forms, as it appears to us, the most sound and rational solution of the nature and origin of many forms of true hermaphro- ditism which physiological science is capable of affording, upon our present limited know- ledge of the laws of development ; and its application to the explanation of the different varieties of lateral, transverse, and vertical her- maphroditism is so obvious as only to be required to be alluded to. It offers to us, however, no insight into the probable origin of those varieties of double hermaphroditism in which there is an actual co-existence upon one or upon both sides of the body, or, in other words, in the same segment of the sexual apparatus, of both the corresponding male and female organs. We can only refer all such instances to the laws which regulate the occa- sional production of local duplicities indiffe- rent other organs of single bodies, and at the same time confess our present ignorance of what these laws are. We know that various individual muscles, nerves, &c. are not unfre- quently found double, and that in the internal organs of the body examples of duplicity in individual viscera are occasionally, though rarely, observed in the heart, tongue, trachea, oesophagus, intestinal canal, &c. In the several organs composing the reproductive apparatus, instances of similar duplicity would seem to be even more common than among any other of the viscera. Examples of three mamma? upon the same person are mentioned by Bartholin,* Borelli,-f Lanzoni,I Drejer,§ Robert,|| Petrequin,1f and others;** and cases in which the number of these organs was in- creased to four have been recorded by Faber,+f GardeuXjJt Cabroli,§§ Lamy,|||| Tiedemann,^ Champion,*** Sinclair,-^} ft. Lee,Jtt and Moore. §§§ An instance in which jive mam- ma even existed upon the same woman is re- ported to have been seen by Gorre.|||||| Valen- tin^l^fir and Gunther**** have recorded sup- posed cases of duplicity in the male penis ; and Arnaudfttt nas related an example of an ana- logous malformation in the female clitoris. WeberJJJJ met with a double vesiculaseminalis * Acta Med. Hafn. torn. iii. obs. 93. t Ohserv. Kar. cent. i. p. 55. t Eph. Nat. Cm. Dec. ii. Ann. v. obs. 55. § Arch. Gen. de Med. torn. xvii. p. 88. [) J urn. Gen. de Med. torn. c. p. 57. 1] Gazette Medicale for April,) 1837. Three distinc t mammas in a father, and in his three sons aud two daughters. ** Diet, des Sc. Med. torn, xxxiv. p. 529. tt Eph. Nat. Cur. Dec. i. Ann. ii. p. 346. Journ. de Med. de Corvisart, torn, ix, p. 378. 4§ Obs. Anat. vii. (Ill Pantoni Anat. p. 267. *l\ 11 Zeitschrift fur Physiologie, lid. v. s. 110. One case with three, and three with four nipples. In one case the malformation was hereditary. **" Diet, des Sc. Medic, t. xxx. p. 377. See also p. 378. ttt Statistical Account of Scotland, xix. p. 288. tti London Med. -Chirurg. Trans, vol. xxi. p. 266. §§§ Lancet for February 24, 1838. Mill Diet, des Sc. Med. torn, xxxiv. p. 529. Eph. Nat. Cur. Dec. iii. Ann. iii. obs. 77. **** Cohen vom Stein, Halle, 1774, p. 107. fttt Mem. de Chir. torn. i. p. 374. llli Salzburg Mediciuische Zeitung, 1811, s. 188. HERMAPHRODITISM. 727 on each side ; and Hunter* alludes to the occa- sional occurrence of an imperfect supernumerary vas deferens. In 1833 a case of a doable human uterus, furnished with four Fallopian tubes and four ovaries, was shewn by Professor Moureau to the Academie de Medecine.f BlasiusJ dissected the body of a man on whom he detected the co-existence of three testicles ; the additional testicle was of the natural form and size, and was furnished with a spermatic artery and vein that joined in the usual manner the aorta and vena cava; it lay in the right side of the scrotum. Arnaud found, on dissection, three testicles in a dog; the third was placed in the abdomen, and of the natural consistence, figure, and size ; it was furnished with a vas deferens.§ Other instances of triple and quadruple testicles of a more doubtful charac- ter, inasmuch as the observations made during life were not confirmed by dissection after death, are related by Voigtel,|| Sibbern,1[ Brown,*"* Rennes,ff and others.f]; ScharfT§§ even gives an alleged case of a man with five testicles, three of which are stated to have been well formed, while the other two were much smaller than natural. And, lastly, Loder|||| is said to have exhibited to the Goettin- gen Academy drawings taken from the body of a male infant, on whom all the sexual apparatus existed double, there being two penes, a double scrotum, and urinary bladder, and, as it was supposed, four testicles. In all the preceding instances the local duplicity of the particular reproductive and other organs adverted to existed independently of any duplicity in the body in general, or in any other individual parts of it. And if we once admit, (what the preceding instances will scarcely allow us to deny,) that there may occur a duplicity of some of the male sexual organs in a male, or of some of the female sexual organs in a female, it is certainly easy to go one step farther, and admit that the double organ or organs may, however rarely, be formed in other instances upon an opposite sexual type. Indeed all our knowledge of the unity of structure and development between the various analogous male and female repro- ductive organs, as well as the fact of the occa- sional replacement of an organ of the one sex by that of the other in cases in which the sexual type is entirely single (as seen in instances of lateral hermaphroditism), would lead us a priori to suppose that, if a local duplicity in any of the sexual oi trans was liable to occur, this duplicity would sometimes shew itself in the double organs assuming opposite * Bell's Anatomy, vol. iii. p. 428. t Journ. Hebdom. torn. x. p. 160. i Ubs. Med. pars iv. obs. 20. § Mem. de Chirurg. s. i. p. 131. (J Handbuch der Path. Anat. Bd. iii. s. 393. If Acta Hafn. torn. i. p. 320. ** New York Medical Repository, vol. iv. p. 801. ft Arch. Gen. de Med. t. xxiii. p. 17. tt See Haller's El. Phys. torn. v. p. 411, 12.— and Arnaud's Chem. de Chirurg. t. i. p. 128, &c. v4 Eph. Nat. Cur. Dec. iii. Ami. v. vi. obs. 89. |||| Gbttingen Anz. 1802, p. 466. sexual characters, and thus constituting some of those varieties of double or vertical her- maphroditism that we have already had occa- sion to describe. In the preceding observations we have pro- ceeded upon the opinion commonly received by physiologists, of the fundamental unity of sex among all individuals belonging to the higher orders of animals; or, to express it otherwise, we have assumed that each individual is, when normally formed, originally furnished with elemental parts capable of forming one set of sexual organs only. We do not here stop to inquire whether this single sexual type is, in all embryos, originally female, as main- tained by Rosenmiiller, Meckel, Blainville, Grant, and others; or, of a neutral or inter- mediate character, as supposed by the St. Hilaires, Sevres, Ackermann, Home, &c, and as we are certain'y ourselves inclined to believe it.* On this subject, however, a physiological doctrine of a different kind has been brought forward by Dr. Knox, and this doctrine is so intimately connected with the question of the nature and origin of true hermaphrodites, that we must here briefly consider it. Dr. Knox,f in conformity with some more general views which he entertains on tran- scendental anatomy, is inclined to regard the type of the genital organs in man and the higher animals, as in the embryo, originally hermaph- roditic, or as comprising elementary yet dis- tinct parts, out of which both sets of sexual organs could be formed ; and lie believes that, owing to particular but unknown circum- stances, either the one or the other only of these sets of elements comes to be evolved in the normal course of development. In those abnormal cases, again, in which, as in instances of double hermaphroditism, more or fewer of both sets of genital organs are present upon the same individual, he maintains that this is not to be considered as a malformation by duplicity, but is only a permanent condition of the original double sexual type, and is attri- butable to the simultaneous development to a * Meckel (De Duplicitate Monsirosa, p. 14), and Andrnl (Anat. l ath. torn. i. p. 101) assume it, after Haller, as a fact, that a much larger pio- portion of monsters belong to the female than to the male sex ; and while they attribute this circum- stance to the genital organs in these beings retain- ing, from the general defect of development, their original female sexual character, they at the same time consider this circumstance to be strongly corroborative of this particular doctrine. Isid. St. Hilaire has shewn (Hist, des Anomal. t. iii. p. 387) that the supposed fact itself does not hold true in respect to some genera of monsters, and is even reversed in others ; and he doubts if it be of such a degree of generality in respect to mon- sters in general as to merit to be raised into a teratological law. If the views of Meckel were correct, we should certainly expect at least that spurious hermaphroditism, where the development of the sexual parts is commonly abnormal from defect, should be much more frequent in the female than in the male. The list, however, of recorded cases of it in the latter is, we believe, more than double the number of it in the former. + Brewster's Edinburgh Journal of Science, vol. ii. p. 322. 728 HERMAPHRODITISM. greater or less extent both of the male and female sets of sexual elements. This doctrine of the original but temporary double sexed character of all embryos derives, perhaps, its principal support from a source to which Dr. Knox does not advert, — we mean the existence of this as the normal and perma- nent sexual type in most plants and in many of the lower orders of animals. But this argument by analogy certainly cannot by any means be considered as a sufficient basis for the establish- ment of so broad and important a generalization in philosophical anatomy. Dr. Knox himself seems to have been induced to adopt the idea principally because it afforded (when once assumed as a fact) a simple and elegant solution, upon the laws of development, of the occa- sional occurrence of cases of true hermaphro- ditism ; and in doing so, he appears to have proceeded upon the mode in which most such physiological hypotheses have been made, viz. by drawing his premises from his deductions instead of his deductions from his premises. In the present state, however, of anatomical and physiological knowledge, Dr. Knox's hypo- thesis, however ingenious in itself, is one which we cannot subscribe to ; for first, it is totally opposed to all the facts which have been ascer- tained, and all the direct observations which have been made by Ratlike, Meckel, Muller, Valentin, and other modern anatomists upon the sexual structure of the embryos of the higher animals in their earliest state; and, secondly, if we were to admit it merely as a probable hypothesis, it is still even in this respect equally as incapable as the old doctrine of sexual unity, of explaining all the cases of malformation by duplicity of the genital organs; for, as we have already shewn, there are some apparently well-authenticated instances of the existence of three or four testicles upon the same man, or three or four ovaries upon the same woman ; and in reference to all such cases we would, if we proceeded upon the same data and the same line of argument as those adopted by Dr. Knox, be obliged to suppose that the original sexual type is not, as he ima- gines, double only as respects the two sexes, but double even as respects each sex, and that all embryos had originally not simply the ele- ments of two, but those of three or four testicles and ovaries. In explaining such cases as those to which we allude, Dr. Knox, on his own doctrine, must of necessity admit the existence of a malformation by duplicity of the sexual organs in question ; and if we grant this in regard to these instances, it is surely unne- cessary to invent a particular and gratuitous hypothesis for the explanation of the analogous anatomical anormalities observed in hermaph- roditism. At present we must, we believe, merely consider the occurrence of anomalous duplicity of the sexual organs, and of various other individual parts of the body, as so many simple empirical facts, of which we cannot, in the existing state of our knowledge, give any satisfactory explanation, or, in other words, which we cannot reduce to any more simple or general fact; though from the success which has attended the labours of many modern investigators in this particular department of anatomy, it seems to us not irrational to hope that ere long we may be enabled to gain much new light upon the question of double her- maphroditism and the whole subject of mal- formation by duplicity. ANATOMICAL DEGREE OF SEXUAL DUPLICITY IN HERMAPHRODITISM. Though the cases which we have brought forward do not present any instances of such perfect hermaphrodites in the human subject or in quadrupeds as those which are represented upon the ancient Greek statues and medals, * or that have been described and delineated by Lycosthenes, Pare, Schenkius, and the older authors on monstrosities, they yet present to us a sufficient number of instances in which, in accordance with the definition we have pre- viously given of true hermaphroditism, there actually co-existed upon the body of the same individual more or fewer of the genital organs both of the male and female. From the relations and size of the bony pelvis, and the fact of the penis and clitoris being re- petitions only in situation and structure and organic connections of each other in the two sexes, it is useless perhaps to expect that we should ever find in any one case all the parts of both sexes present at the same time. For since the male penis is only a magnified condi- tion of the female clitoris, and since both of these organs are connected by the same anatomical relations to the same part of the pelvis, it would almost require some duplicity in the pelvic bones themselves to admit of the simul- taneous presence of both ; and in no authentic case has any approach to their co-existence upon the same individual been observed. Various authors who have written upon the subject of hermaphroditism have gone so far as to endeavour to refer all instances of it to some one or other of those varieties that we have described under the name of spurious. Thus, dogmatizing in a spirit of unphilosophical scepticism, Parsonsf and Hill J have endea- voured to shew that all reputed hermaphro- dites are only malformed females having a preternatural development of the clitoris, and in some instances with the ovaries descended into the labia. Others, on the contrary, as * See Winckelman, Hist, de l'Art, t. i. p. 364; and Caylus, Recueil d'Antiquites, t. iii ; Heinrich, Commentatio qua Hermaphroditorum artis antique operibus illustrium, origines et causae explicantur. Hamburg, 1805. IJlumenbach, in his Specimen Hist. Nat. Antiq. artis ( Goetting, 1808), mentions and figures (pi. i. f. 5, p. 15), a small ancient sil- ver cast or impression of a case of hypospadias of the male genital parts, which he supposes to have formed a votive offering from some individual mal- formed in the manner represented. t Enquiry into the nature of Hermaphrodites, p. 145. We would particularly point out the cases quoted by Dr. Parsons at p. 14, 26, 30, 88, 95, 130, &c. of his able essay as directly contradictory of his own doctrine, or as instances of hermaphroditic appearances in persons not of the female but of the male sex. | Review of the Philosophical Transactions. HERMAPHRODITISM. 729 Professors Osiander* and Fei!er,f maintain with equal inaccuracy that every supposed in- stance of hermaphroditism is referable to a hypospadic state of the penis and scrotum, in persons that are in other respects essentially male. Various physiologists, again, while they ad- mit the occurrence of all the different varieties of spurious hermaphroditism, are inclined to deny that anv such combinations of male and female organs upon the same body as those which constitute our several varieties of true hermaphroditism, are ever observed to occur in the human subject, or among the higher classes of animals.f In despite of the recent accumulation of new and authentic cases, Pro- fessor Muller of Berlin is, in particular, in his excellent treatise on the development of the genital organs, published in 1830,§ still in- clined to coincide in a great degree in this opinion. This distinguished physiologist does not indeed, as some have done, doubt in any degree the authenticity of the recorded cases, and even goes so far as to admit the occasional occurrence of a combination of male and female organs upon the same individual, when that combination does not (as in lateral and trans- verse hermaphroditism) imply a true sexual duplicity or repetition of any of the cor- responding male and female parts ; but he doubts altogether the probability of our third division of double or complex hermaphroditism, and conceives that in the examination of the cases referable to that section a sufficient degree of attention has not been directed to the ac- curate anatomical distinction of the particular parts supposed to exist, from others with which it is possible to confound them. We shall here, therefore, shortly inquire into some of the principal sources of fallacy which are apt to mislead the incautious observer in the examina- tion of such instances as those to which we allude ; and in doing so we shall consider the various sources of error in an order conformable with those divisions of double hermaphroditism that we have previously adopted, — speaking of the mistakes which may be committed in judg- ing of the supposed co-existence, 1st, of a female uterus, and male vesicula; seminales and vasa deferentia ; 2d, of a female uterus and male testicles, &c. ; 3d, of both testicles and ovaries. 1 . Fallacies in judging of the addition of male seminal ducts to a female tape of sexual organs. — That form of sexual duplicity which we have formerly described as consisting in the supposed superaddition of male vesiculae semi- nales and vasa deferentia to an organization in other respects female, appears to have been * Neue Denkwuerdigk. fur Geburtshiilfe. Bd. i. n. 8. t Ueber Angeb. mensliche Misbildung. Land- shut 1820. f Thus Portal, Anat. Med. t. v. p. 474; Haller, El. Phys. t. viii. p. 7, " merito dubitatur j" Voigtel, Handbuch der Path. Anat. Bd. iii. s. 364; Lawrence, Art. Generation, in Rees's Cyclopaedia. § Bildunsgeschichte der Genitalien. hitherto observed principally, or indeed only among the Ruminantia, and has in particular been repeatedly found in free-martin cows. In judging of the reality of this variety of herma- phroditic malformation in any given case, there is one source of fallacy that requires to be par- ticularly guarded against, and the consideration of which may probably go far to explain away most of the recorded examples of the mal- formation. In the female sexual parts of some Ruminantia and Pachydermata,* but particu- larly in the domestic cow and sow, Dr. Gaert- ner of Copenhagen pointed out in 1822f the existence of two canals or ducts which have since that time been generally described under his name. On each side of the body, one of these ducts arises in the vicinity of the ovary, or near the fimbriated extremity of the Fallopian tube, runs dov."n first in the duplicature of the broad ligament, and afterwards in the sub- stance of the parietes of the uterus and vagina, to near the meatus urinarius, and there opens into the vaginal cavity. Each duct communi- cates with several small glands, follicles, or cysts that are scattered along its course, and which perhaps may not be improperly described as diverticula from the ducts themselves. Now when we consider the relations of those imper- fect ducts and cysts that are occasionally ob- served in the free-martin cow, situated along- each side of the defectively developed uterus, and which Mr. Hunter has described as male vasa deferentia and vesiculae seminales, it seems to us not at all improbable that these supposed male organs are only in reality the ducts of Gaertner, with their accompanying follicles or cysts generally perhaps existing in a morbidly developed and dilated condition. They seem at least to correspond much in their origin, course, and position with the canals and cysts discovered by Gaertner ; and certainly in the present state of our knowledge it would appear more reasonable to refer them to this normal portion of the female structure, than to regard them, until we have more decided evidence on the subject, as abnormal male organs, and as affording, in consequence, an example of sexual duplicity. In the course of the preceding pages we have had occasion to allude to cases in the human subject, and in the dog and sheep, in which vasa deferentia were stated to have existed in the same individual along with Fallopian tubes. Whether, in any of these instances, the supposed male seminal ducts were merely canals analogous to those described by Gaertner in the cow and sow, we shall not take it upon us to determine, but in connection with this inquiry it is interesting to remark that Malpighi, who seems to have been well ac- quainted with the existence of the ducts in the * M. Delmas seems to have observed a somewhat similar structure in the Kangaroo. (Ephem. Medic, dc Montpellier, t. v. p 115.) t Anatomisk Beskrivclse over et ved Nogle Dyr- Ai'ters uterus nndersogt Glandulbst organ, &c. Co- penhagen, 1822 ; Edin. Med. and Surg. Journ. vol. xxi. p. 460. 730 HERMAPHRODITISM. cow, has suggested that they may also exist in a more obscurely developed state in the human female, and may perhaps be identified with the ramous lacunae described by De Graaf, Bar- tholin, Riolan, &c. A. C. Baudelocque has, in a case published in the Revue Medicale for March 1826, described a human uterus which contained in its parietes a canal coming from the right Fallopian tube, and opening upon the internal surface of the cervix uteri ; and Moureau and Gardien seem to have met with a second (?) similar instance.* Before leaving this subject of the probable source of fallacy which we have to guard against in confounding the ducts of Gaertner with the male seminal canals, it is necessary also to observe, that some anatomists! are now inclined to consider these canals as the perma- nent remains of the ducts of those Wolffian bodies which we shall presently have occasion to allude to more at length, as forming a tem- porary type of structure in the sexual develop- ment of the early embryo ; and certainly the two appear to accord in most points with respect to their situation and course. If, how- ever, it happens that further and more accurate observations prove the two to be different, then the possible permanent state of the ducts of the Wolffian bodies must be looked upon as affording another source of error, by which we may deceive ourselves in judging of sexual duplicity from the supposed superaddition of male seminal canals to a female sexual apparatus. 2. Fallacies in the supposed co-existence of a female uterus with testicles and other organs of a male sexual type. — We have, in a pre- vious part of this communication, adduced about twenty different instances in the human subject, and in the quadruped, in which a female uterus, or both an uterus and Fallopian tubes were described as having been found upon the bodies of individuals that were in other respects essentially males. In reference to some of these instances it has been doubted whether the sexual organiza- tion of the malformed animal was not entirely male, the supposed and generally imperfect uterus being conceived to be formed either by a morbid dilatation and unfolding of the sub- stance of the male prostate gland, or by an abnormal union and development of the vesi- culoe seininales. Thus, in the case detailed by Ackermann, the only male sexual organ that was entirely deficient was the prostate, and the only reputed female organ which was present was an imperfect cystiform uterus differing greatly in structure from the form of this organ in the infant, and having, as in the normal state of the prostate, the vasa deferentia pene- trating through its substance without opening into its cavity, and ultimately terminating along * Medical Repository for 1826, p. 571. f As Jacobson of Copenhagen in Journal de l'lnstitut, t. ii. p. 160; and Die Okenschen Koerper, &c. Copenhagen, 1830. with it in the posterior part of the urethra. In the analogous instance quoted in a preceding page from Steghlener, a similar arrangement of parts was observed; and in that case there was, in the enlarged ureters and renal infundibula, sufficient evidence (as we shall afterwards point out when speaking of the probable causes of hermaphroditism) of a distending power having acted upon the whole internal surface of the urinary and genital organs, and with so great a force (we may in the meantime allow) as to be capable of producing such a morbid dilatation and unfolding of the substance of the prostate as the doctrine alluded to requires. Such an effect would be the more liable to be produced if we can suppose this latter organ to have been disposed, by original tenuity of its coats, or by morbid softening or other diseased st.ites of its tissues, to yield more easily to the dilating power, than any of the other surfaces to which it happened to be applied. At the same time, however, we confess that we conceive it unphi- losophical to endeavour to account for alt the cases which we have previously quoted of the addition of a female uterus to a male type of sexual organization upon this mechanical prin- ciple, or to attempt to explain away, in the mode we have just referred to, the evidence which these cases afford of the occasional occurrence of this combination as a true form of sexual duplicity. For even granting that the instances given by Ackermann and Steghlener, and per- haps one or two other cases, are not at all satisfactory in regard to the reputed existence of such a variety of sexual duplicity, and allowing, what seems indeed not at all impro- bable, that the supposed very imperfect uterus in these examples was merely an organ formed by a dilatation of the prostate and seminal ducts, there is still a sufficient abundance of cases left to which this explanation cannot possibly apply. Thus, in the person dissected by Petit, the imperfect uterus was furnished with two per- forate Fallopian tubes of three and a half inches in length, and at the same time it is distinctly stated that not only the prostate gland, but the vesiculre seminales and vasa deferentia were also present. The vasa defe- rentia, between their origin from the testicles and their urethral termination, were each above seven inches long, and they entered the urethra by two apertures that were quite distinct and separate from the orifice of the uterus, which opened into the urethral canal at a point placed between the neck of the bladder and the prostate. In this case we cannot suppose that the uterus and Fallopian tubes were formed at the expense of the prostate gland or male seminal ducts, as they and all the other male organs were present ; and consequently we can only consider the female organs as a super- addition to, and not a transformation of the male structures; or, in other words, we must look upon the above as an instance of duplicity in a part of the sexual apparatus. The same reasoning and remarks might be shewn, if it were necessary, to apply in a greater HERMAPHRODITISM. 731 or less degree to the other analogous examples in the human subject given by Harvey and Professor Mayer,* as well as to the hermaphro- ditic sheep described by Thomas, and the diffe- rent cases in the goat mentioned and delineated by Guilt and Mayer. In all these latter cases in the quadruped, the male organization appears to have been perfectly developed, the testicles, epididymes, vasa deferentia, and vesiculae semi- nales being present in all of them ; and in Thomas's sheep the superadded female uterus shewed internally the usual characteristic rugose structure, while its cornua terminated in two long Fallopian tubes. In Guilt's goat case all the internal male sexual organs were found, with the exception of Cowper's glands; and yet we cannot suppose that these glands could have been transformed and moulded out into that distinct and hollow uterus with its two very long curved cornua, which the reporter has re- presented as being present ; not to mention the total want of any collateral evidence in this and in the other cases to which we have just now referred, of any dilating power having acted upon the genital or urinary organs in the em- bryo. 3. Fallacies in the supposed co-existence of testicles and ovaries. — In several of those in- stances in which there has been supposed to be a co-existence of both testicles and ovaries upon the same side or sides of the body, it seems highly probable that there has been a fallacy in the observation, owing to a want of knowledge of some anatomical circumstances that are liable to lead us into error in making an examination of such a case. We have previously had occasion to allude to the existence in the foetal state of the Wolffian bodies, which are placed one along each side of the spine, and occupy at an early period in the embryo a great part of the cavity of the trunk. These bodies, as is now well known from the investigations of Rathke, Meckel, Midler, Burdach, and others, form in Mam- malia and Birds at least, and equally so in both sexes, the primordial matrices of the geni- tal and urinary organs (see article Ovum), and in the natural course of development altogether disappear in man and in the quadruped during the earlier periods of development, leaving no vestige of their presence in the extra-uterine animal. This particular foetal type of structure, like every other temporary type of the embryo, may, from an impediment or arrest in the natu- ral course of the changes occurring in the deve- lopment of the body in general, or of the genital organs in particular, become, we have every reason to believe, occasionally permanent in one or more of its parts, and thus by its pre- sence in the animal lead us to suppose that a rudimentary testicle exists in an otherwise well- marked female, or, on the other hand, that an ovary exists in an otherwise well-marked male. Both of these mistakes will be the more apt to be committed if the original excretory duct of * See his second case in the foetus and those of the two adults in a preceding page. the Wolffian body remains, for it may give the appearance of the addition of a vas deferens to the supposed testicle, or of a Fallopian tube to the supposed ovary. The error, also, of confounding a permanent Wolffian body with the testicle will be the more liable to occur, in consequence of the former body being naturally composed of an accumulation of convoluted diverticula which might be readily mistaken by an incautious ob- server for the seminiferous ducts of the latter. There is certainly strong cause for doubting whether, in some of the cases that we have cited of the supposed co-existence of testicles and ovaries upon the same sides, the uniemoved Wolffian bodies and their ducts had not either been mistaken for testicles and vasa deferentia, while the sexual organization was otherwise truly female, or for ovaries and Fallopian tubes, while the type of structure was in other respects strictly that of the male. This remark may perhaps with confidence be applied, for ex- ample, to the case of the free-martin described by Mr. Hunter ; and in this and in most other similar instances the supposed testicles and ovaries have not been at all examined with any thing like sufficient anatomical ac- curacy. At the same time, however, it ap- pears to us impossible to explain away all the recorded cases of the supposed co-existence of testicles and ovaries upon this principle. In reference to this point we would particularly observe that the consideration of the relative position occupied by the reputed testicles and ovaries may perhaps afford us an useful guide in cases of doubt. In some of the instances that have been previously cited, the relative situation of the supposed testicles and ovaries was exactly such as the Wolffian bodies are known to bear to these parts. In other in- stances, however, as in the ape described by Dr. Harlan, the relative situation in which the testicles and ovaries were found, was that which they occupy in the perfectly formed male and female ; and in such a case as this it would surely be over-sceptical, and at the same time in opposition to all that we yet know of the history of the Wolffian bodies, to suppose that these bodies had imitated the testicles so far as to move out of their original locality and travel downwards through the inguinal rings. At the same time we must recollect that in this case the distinctive anatomical structure both of the testicles and ovaries seems to have been satis- factorily made out, in so far that the former are described as " perfectly formed," and the latter as having " minute ova visible in them." " The male and female organs of generation," Dr. Harlan adds," were as completely perfected as could have been anticipated in so young an in- dividual, and resembled those of other indivi- duals of a similar age." Now if we once admit in this, or in any one other particular instance, that the evidence of the co-existence of testicles and ovaries is satisfactory, then certainly we may in any equivocal case be entitled to doubt until we have some more sufficient criterion for distinction pointed out, whether the dubious double bodies that we may meet with be a 732 HERMAPHRODITISM. rudimentary testicle or ovary conjoined with an imperfect Wolffian body, or really a true in- stance of the presence of both testicles and ovaries upon the body of the same individual. PHYSIOLOGICAL DEGREE OF SEXUAL PERFEC- TION IN HERMAPHRODITES. Among those lower tribes of animals, such as the Abranchial Annelida, Pteropoda, &c. that are naturally hermaphrodite, every individual is in itself a perfect representation of the species to which it belongs. In the higher orders, however, in which the distinction and separa- tion of the sexes comes to be marked, each in- dividual being either solely male or solely female, can, as has often been remarked, be re- garded only as representing one-half of its entire species. In most instances of hermaph- roditism among these more perfect animals, the malformed being does not even attain to this degree of perfection, but is in general so defec- tively constituted as not to have the proper physiological characters and attributes of either sex. In cases of spurious hermaphroditism it would appear that sometimes, though the co- pulative or external sexual parts are greatly and variously malformed, the internal or proper re- productive organs are developed with sufficient perfection to enable them to perform the func- tions belonging to them. We have very little proof, however, that in any instances of what we have described as true hermaphroditism, the apparatus of either sex is even formed with such anatomical perfection as to empower the malformed being to bear a successful part in the reproductive function. Indeed in all, or in almost all cases belonging to this last order of hermaphroditism, the individual who is the subject of the malformation may, with much more than poetical truth, be described both anatomically and physiologically, as, in the words of Ovid, Concretus sexu, sed non perfectus utroque, Ambiguo venere, neutro potiundus amore. There is on record one remarkable instance of apparent exception to this general observa- tion, a notice of which we have reserved for this place on account of the want of any such precise knowledge of the true anatomical pecu- liarities of the case as might enable us to refer it to the section which it ought to occupy in our classification. The case to which we allude was described by Dr. Hendy of New York, in a letter dated from Lisbon in 1807, and the subject of it was a Portuguese, twenty- eight years old, of a tall and slender but mas- culine figure* " The penis and testicles," to adopt the words of Dr. Hendy 's own narrative, " with their common covering the scrotum, are in the usual situation, of the form and appear- ance, and very nearly of the size of those of an adult. The praeputium covers the glans com- pletely, and admits of being partially retracted. On the introduction of a probe, the male ure- thra appeared to be pervious about a third of its length, beyond which the resistance to its passage was insuperable by any ordinary justi- - * New York Medical Repository, vol. xii. p. 86. fiable force. There is a tendency to the growth of a beard, which is kept short by clipping with scissors. Thefemale parts do not difierfrom those of the more perfect sex, except in the size of the labia, which are not so prominent, and also that the whole of the external organs ap- pear to be situated nearer the rectum, and are not surrounded with the usual quantity of hair. The thighs do not possess the tapering fulness common to the exquisitely formed female ; the ossa ilii are less expanded, and the breasts are very small. In voice and manners the female predominates. She menstruates regularly, was twice pregnant, and miscarried in the third arid fifth months of gestation. During copulation the penis becomes erect. There has never ex- isted an inclination for commerce with the female under any circumstances of excitement of the venereal passion." In the preceding case, (if we may confidently trust to the account given of it,) we have ample proof of the exist- ence of the internal female sexual organs in the circumstances of menstruation and impregna- tion taking place ; and at the same time there appears considerable evidence for believing that some of the male organs were present. For even if we were to argue that the bodies present in the scrotum or united labia might be ovaries and not testicles, and that the supposed semi-perforate penis was only an enlarged cli- toris, still the masculine figure of the individual, the imperfect beard, the narrowness of the pelvis, and the form of the lower extremities would tend to indicate the probable existence of the rudiments of some male organs ; and if we go so far as to admit this, we must further allow the present to be an instance of hermaph- roditism, in which one of the sets of sexual organs was capable of assuming their appro- priate physiological part in the process of re- production, though perhaps unable, if we may judge from abortion having twice occurred, of ultimately perfecting that process. The preceding remarks upon the functional reproductive powers of reputed true hermaph- rodites have been meant to apply only to the supposed perfection ofo?;e order of their sexual organs. It becomes a still more interesting question whether it ever occurs that in any ab- normal hermaphrodite among the more perfect tribes of animals, both kinds of sexual parts may be found in so perfectly developed a state as to enable the individual to complete the sexual act within its own body ; or, in other words, to impregnate and be impregnated by itself. Though we have assuredly no positive proof to furnish * that a hermaphrodite so phy- siologically perfect has ever yet been observed, and should very strongly doubt its occurrence * We do not certainly feel entitled to place among the category of correct observations either the alleged case given by Linneus (Mangetus' Bib- liotheca Chirurg. lib. iv. ) of a sow with perfect male organs on one side, and a womb containing several foetuses on the opposite ; or that mentioned by Faber (Hernandez' Nov. Plant. Anim. Mexic. Histor. p. 547) and quoted by Haller and JRudolphi, of the co-existence, in a rat, of ovaries and a uterus with nine foetuses, along with complete male organs. HERMAPHRODITISM. 733 from the almost universal imperfection, in an anatomical point of view, of the malformed or- gans, yet we have, on the other hand, no very ra- tional ground, except that of the experience of all observers up to tiie present date, for denying entirely and unconditionally the utter possibi- lity of it. And peihaps we should look upon this possibility with a less degree of scepticism when we consider that a double hermaphrodi- tism exists as the normal sexual condition of some of the lower tribes of animated beings, and at the same time take into account the fact of the more or less direct communication which has been generally found to exist between the female uterus and the male passages, in cases of lateral and of complex hermaphroditism in the human subject and in quadrupeds. In one of the cases of hermaphroditism in the goat, previously quoted from Mayer, and where there weie present two male testicles, epididymes, vasa deferentia, and vesiculse semi- nales, and a female vagina, uterus and Fallo- pian tubes, with a body at the abdominal ex- tremity of one of these tubes that was supposed by Mayer to resemble a collection of Graafian vesicles, the male vasa deferentia opened into the female vagina; and its cavity with that of the uterus, and of all the male sexual canals, was distended with a whitish fluid of the odour and colour of male semen, and containing, ac- cording to Bergmann, the chemical principle proper to that secretion. It is not, therefore, altogether without some appearance of founda- tion in fact, that Mayer has added to the history of this case the following proolematical remark : " Fuit ergo revera hermaphroditus semetipsum fcecundare studens."* In a similar strain Dr. Harlan has added to the account that he has given of the very com- plete case of hermaphroditism already men- tioned as met with in the Borneo ourang- outang, the following observations and queries. " Admitting," he remarks, " what in reality appeared to be the fact, that all the essential organs of both sexes were present in this indi- vidual, had the subject lived to adult age, most interesting results might have been elicited. Could not the animal have been impregnated by a male individual, by rupturing the mem- brane closing the vulva ? or by masturbation, might not the animal have impregnated itself? by this means exciting the testicles to discharge their seminal liquor into its own vagina. The imperfection of the urethra most probably would have prevented the animal from ejecting the semen into the vagina of another indivi- dual."! It has been sometimes urged as an argument conclusively illustrative of the fact of a double hermaphrodite impregnating itself, that in the hermaphrodite Gustrophoga pini described by Scopoli,]; the insect is stated to have been seen to advance its penis and copulate with its own female organs ; and afterwards, we are inform- ed, the female side laid eggs from which young * Icones, &c. p. 20. t Medical and Physical Researches, pp. 23, 24. $ Introd. ad Hist. Nat. p. 416. caterpillars were produced. Before, however, admitting this case to present an incontroverti- ble instance of absolute hermaphroditism, with the functions of the two sets of sexual organs existing in a perfect condition upon the same individual, it is necessary to recollect a possible source of fallacy in this circumstance, that female Gastrophagi have been observed to lay fertile eggs, although they had not had pre- viously any connection with the male, as re- marked by Professor Baster* in one instance in a female Gustropluiga quercifolia, and in ano- ther in the Gastrophaga pini by Suckow.f The same fact is further alleged to have been ob- served in some few instances by Pallas, Trevi- ranus, Bernouilli, and others,! in regard to in- dividuals belonging to some other of the higher orders of insects and animals, as in the Lii/uoeus auriculariaS} and Helix vivipara\\ among Mol- lusca, thus bringing them in this respect into analogy with the Aphides and Cyprides. CAUSES OF HERMAPHRODITIC MALFORMATION. As yet we possess very little accurate know- ledge either in respect to the mode in which the determining causes of hermaphroditic mal- formation act, or the nature of these causes themselves. Most of the varieties of spurious herma- phroditism may, as we have just explained, be traced to an arrest in the development of the sexual organs at one or other period of their evolution, in consequence of which some of those types of structure in these parts which were intended to be temporary and transitory only, are rendered fixed or permanent in their character. Our knowledge of the more imme- diate causes of such arrested development in these and in other individual parts and organs of the body, is as yet extremely limited, and for the discussion of it we must refer to another part of the present work, (see article Mon- strosities). We may, however, in reference to the particular forms of arrested development observed in hermaphroditism, remark that in consequence of the great influence which, as we have already pointed out, is exercised by morbid states of the ovaries and testicles, in retarding or preventing the evolution of the sexual apparatus and characters after birth, it has been suggested with considerable probabi- lity by Meckel^! and Isidore St. Hilaire,** that in their ultimate analysis certain cases of her- maphroditic malformation may be traced in the course of their causation to morbid influences exercised in the early embryo, at a period more or less near to conception, upon the ovaries or testicles, or upon those organs of a neuter or yet undetermined sex which after- wards assume the structure of one or other of * Mem. de l'Acad. Roy. de Berlin, 1772. t Heusinger's Zeitschrift fiir Organ. Phys. Bd. ii. s. 263. t Burmeister's Entomology, s. 204. Burdach's Physiologie, t. i. § 44, 4-8. « Isis for 1817, p. 320. |] Spallanzani, Mem. sur la Resp. p. 268. II Anat. Geu. t. i. p. 609. ** Hist, des Anomal. de l'Organiz. t. ii. 58. 734 HERMAPHRODITISM. these bodies. Further, the effects which this supposed morbid influence exercises directly upon the embryonic ovaries and testicles, and indirectly through them, upon the rest of the genital apparatus, and consequently the modi- fications of sexual structure which it produces, may possibly be much varied according- to its extent, duration, and nature, and according to the particular period of development at which it comes into action. It is evident that this ex- planation of hermaphroditism can only refer to the varieties of the malformation which consist of an imperfection or deficiency in the development, and cannot apply to those in- stances in which there is a superaddition of sexual organs. If, however, we can once satisfy ourselves that any set of cases whatever are traceable to a morbid action affecting the testicles or ovaries of the early embryo, our investigations into the causes of these cases will necessarily be much simplified, for our inquiries would be reduced from a vague and indefinite search after the production of a num- ber of anomalies of structure affecting several different organs at the same time, to an attempt to trace out the nature of those morbid condi- tions to which the embryonic testicles and ovaries were subject, and which were capable of so far changing the structure and action of these organs as to give rise to the effects in question. Of the diseased states, however, to which the reproductive and other organs of the system are liable during the progress of their early development, we at present know little or nothing, although in the investigation of this subject a key, we believe, may possibly be yet found to the explanation of many of those malformations to which different parts of the body are subject. Osiander* and Dugesf have suggested that the variety of spurious hermaphroditism which consists of a division of the peri- neeum in the male, may be produced me- chanically in the embryo by the preterna- tural accumulation of fluid in the urinary canal, on account of an imperforate state of the urethra, and the consequent distension and ultimate rupture of the urethra, &c. From cases published by Sandifort, Howship, Bil- lard, and many others, we are now fully aware of the fact that all the urinary canals of the fcetus in utero are occasionally found morbidly distended with a fluid, which, according to the interesting observations of Dr. Robert Lee. X would appear to possess the more character- istic qualities of urine. We have dissected one case in which the dilated foetal bladder was as large as an orange, and have seen in the Anatomical Museum of Dr. William Hunter at Glasgow the preparation of another instance in which the bladder of a full-grown foetus was dilated to the size of that of the adult subject. In one case mentioned by Dr. Mer- riman, the distended organ contained half a * Neue Denkw. fur Aertzte und Geburtsh, Bd. i. t. 264, 267. t Ephem. Med. de Montpellier, t. v. p. 17, 45, and 52. t London Med.-Chirurg. Trans, vol. xix. pint of urine,* and in another detailed by Mr. Feam it was capable of containing as much as two quarts of fluid.f It is not impossible that the causes in ques- tion,— namely, the obliteration of the urethra and the consequent distention of all the urinary passages, and probably also of the sexual canals communicating with these passages, — may occasionally produce in the male embryo a re-opening of theperinaeal fissure, giving thus to the external parts the appearance of a female vulva, and perhaps at the same time may lead to the retention and imperfect development of the testicles by the distention of their ducts, and the unusual compression to which these organs may be subjected. Indeed we have satisfactory evidence, in a few instances, that such a cause may have been in operation, by our detecting the other acknowledged effects of the urinary accumulation in question, — such as preternatural !y dilated ureters, and a cystic form of the infundibula of the kidneys, as in a case of hermaphroditism given by Mayer, in a human foetus,}; in the kid described by Haller,§ and in the child whose case we have already quoted from Steghlener. (See trans- verse hermaphroditism. ) At the same time the total absence of these collateral proofs in most other cases of hypo- spadias, our knowledge of the fact that the perinseal aperture is in some cases never shut, and the difficulty of conceiving the possibility of its being re-opened when once it is firmly closed, are perhaps sufficient to shew that the cause or causes alluded to produce in but few if any instances the effect here attributed to them. We deem it not uninteresting to point out in this place, under the question of the origin of hermaphroditic malformations, a circumstance which has struck us in considering one or two of the cases in which the sexual apparatus of one side of the body was more imperfectly developed than that of other, viz. that the opposite side of the encephalon was at the same time defectively formed. Thus in the case of Charles Durge, on the right side of whose body there was a well-formed testi- cle, and on the left an imperfect ovary, the right hemispheres of the cerebrum and cere- bellum, but particularly of the latter, were found by Professor Mayer to be smaller and less developed than the left, and the left side of the occiput was externally more prominent than the right. The same author, in the ac- count of his case of hermaphroditism in a person of eighteen years of age, which we have previously quoted,|| and where there was an imperfect testicle, &c. on the right side, but no trace of testicle or ovary in the left, inci- dentally mentions that the right side of the cranium was somewhat prominent, — " dextra pars cranii paullulo prominet," in correspon- * London Med. and Phys. Journ. vol. xxv. p. 279. t Lancet for 1834-35, p. 178. t See p. 8, of Icones, &c. § Comment. Soc. Reg. Sc. Gotting. torn. i. p. 2. f| Icones, p. 12. HERMAPHRODITISM. 735 dence, there is every reason to believe, with a slight predominance in size in the hemispheres of the encephalon of the same side. In ad- ducing these two cases we do not wish to draw any inference with regard to the relation of causation between the size and development of the encephalic mass and the determination of the sex, but would merely point out the facts themselves in the meantime, for the purpose of drawing attention to the subject in the observa- tion of any future similar instances that may happen to occur. In connection with the question of the causes of hermaphroditism, it is interesting to remark that in some instances malformations of the genital organs giving rise to appearances of her- maphroditism have been observed both to be hereditary in particular families, and in other cases to occur among several of the children of the same parents. Thus Heuremann* mentions an example of a family the females of which had for several generations given birth to males who were all affected with hypospadias ; and Lecatf alleges that a degree of hypospadias is not uncommon among families in Nor- mandy. In Rust's Magazine an instance is related of a degree of hypospadias existing in a father and son.] Baum,§ in his essay on con- genital fissures of the urethra, has referred to two instances of the existence of hypospadias in brothers of the same family, the first men- tioned by Walreeht,|| and the second by Gockel.1l Sir Everard Home** found two cases of hypospadias in two children belonging to the same parents. Kauw Boerhaaveff men- tions an example of four hvpospadiac brothers, and Lepechin another instance of three.]:! Naegele has reported a case in which two male twins were both hypospadic,§§ and Katsky |||| and SaviardUK have mentioned similar in- stances. We have already, when treating of transverse hermaphroditism, alluded to another fact long and extensively known among our agriculturists, but first prominently brought before the notice of physiologists by Mr. Hunter, that the free- martin cow, or the cow that is born a co-twin with a male, is generally barren and has its sexual organs more or less defectively developed or hermaphroditically formed.*** In three dif- * Medicin. Beobaclit. Bd. ii. s. 234, and Laroche sur les Monstrnsites de la Face, p. 30. t Armaud, 1. c. p. 312. % Magazin fuer die Gesammte Heilkundc, Bd. xviii. s. 1 13. § De fissuris urethra? virilis fissuris congenitis, p. 54. || Burdach's Metamorphose des Geschlechter, p. 52. f Eph. Nat. Cur. Dec. ii. Ann. 5. (1686), p. 85. ** Comp. Anat. iii. p. 320. tt Nov, Com. Acad. Sc. Petropolit. t. i. p. 61. tab. xi. It Ibid. t. xvi. p. 525. i§ Meckel's Archiv. Bd. v. s. 136. |f|| Acta M. Berol. Dec. 1, torn, ix, p. 61. ff Observ. Chirurg. p. 284. *** From the Romans employing the female noun taura to signify a barren cow, it has been ingeni- ously conjectured that they w re not unacquainted with the free-martin. Thus Columella de Re Rus- ferent instances Mr. Hunter confirmed the fact of the anomalous sexual development of such animals by dissection; and Scarpa* and Gurltf have published some additional ob- servations and cases. We have lately had an opportunity of dissecting the sexual parts of two adult free-martins, and found them, as already detailed, formed after an abnormal and imperfect sexual type ; and our friend Dr. Allen Thomson made some years ago a similar observation upon a free-martin twin fcetal calf. Cases, however, exceptional to the general fact of the sterility and imperfect sexual conforma- tion of the free-martin twin cow are not unfre- quently met with. Mr. Hunter found the sexual organs of a free-martin calf that died when about a month old apparently naturally constituted. He speaks also of having heard of some free-martins that were so perfectly formed in their sexual parts as to be capable of breeding; and different instances of their fe- cundity have been published by Dr. Moulson and others]; since the time that Mr. Hunter directed attention to this subject. In some pretty extensive inquiries which we have made in regard to this point among the agriculturists of the Lothians, we have learned only of two instances in which free-martins proved capable of propagating, and such cases seem to be always looked upon as forming exceptions to the general rule. VVe are not aware that among other uni- parous domestic animals, as the goat, mare, &c , when a female is born a co-twin with a male, this female is sterile, and has its sexual organs hermaphroditically formed, as in the free-martin cow ; and we are sufficiently as- sured that no such law holds with regard to twins of opposite sexes among sheep. Sir Everard Home, in his essay on monstrous for- mations, § mentions that in warm countries nurses and midwives have a prejudice that such women as have been born twins with males seldom breed; and we have found the same prejudice existing to a considerable degree among the lower orders in Scotland. Mr. Cribb,|| of Cambridge, published in 1823 a short paper in order to refute this notion as far as regarded the human subject. He refers to the histories of seven women who had been born co-twins with males. Six of these had children, and the remaining seventh subject alone had been married for several years without any issue. We have ourselves made a series of extensive inquiries of the same nature tica, lib. vi. chap. 22, speaks of " tauras which occupy the place of fertile cows ;" and Varro in like manner (lib. ii cap. 5. ) states that " the cow which is barren is called taura" (quae sterilis est, taura vocatur). There is no evidence, however, that they were acquainted with the particular cir- cumstances relative to birth under which free-mar- tins are produced. * Mem. della Societa Italiana, t. ii. p. 846. f Lerbuch der pathol. Anat. Bd. ii. s. 188. \ Loudon's Magazine of Natural History, vol. v. p. 765. See also Youatt on Cattle, p. 539, Farmers' Magazine for Nov. 1806 and Nov. 1807. & Comp. Anat. vol. iii. p. 333-4. || London Med. Repos. vol. xx. p. 213. 736 HERMAPHRODITISM. as those published by Mr. Cribb, and have obtained authentic information regarding forty- two adult married females who had been born as twins with males. Of these, thirty-six were mothers of families, and six had no children, though all of them had been married for a number of years. Two of the females who have families were each born as a triplet with two males.* In the Medical Repository for 1827 (p. 350) an anonymous author has men- tioned an instance of quadruplets consisting of three boys and a girl, who were all reared : the female afterwards became herself the mother of triplets. Limited as the data to which we here allude confessedly are, they are still amply sufficient to show that in by far the majority of cases the females of twins of opposite sexes are in the human subject actually fertile, and, as some of the cases we have collected show, they are occasionally unusually prolific. On the other hand, however, it may be con- sidered by some that the same data rather tend in a slight degree, as far as they go, to support the popular prejudice of the infecundity in a number of cases of the female twin, and her analogy in this respect with the free-martin cow ; for out of the forty-two instances which we have mentioned, we find six in which the woman has had no children, though living in wedlock for a number of years, or one out of seven of the marriages of such women has proved an unproductive one, — a proportion, we believe, considerably above the average of unproductive marriages in society in general, or among women of any other class. But perhaps, before drawing any very decided conclusion with regard to this point, a more extended foundation of data would be requisite than any we have hitherto been able to adduce, as it is perfectly possible that our having met with six exceptional cases may be a mere matter of coincidence. As to the cause of the malformation and consequent infecundity of the organs of gene- ration in the free-martin cow, we will not ven- ture to offer any conjecture in explanation of it. It appears to us to be one of the strangest facts in the whole range of teratological science, that the twin existence in utero of a male along with a female should entail upon the latter so great a degree of malformation in its sexual organs, and in its sexual organs only. The circumstance becomes only the more inexpli- cable when we consider this physiological law to be confined principally or entirely to the cow, and certainly not to hold with regard to sheep, or perhaps any other uniparous animal. The curiosity of the fact also becomes heightened and increased when we recollect that when the cow or any other uniparous ani- mal has twins both of the same sex, as two males or two females, these animals are always both perfectly formed in their sexual organiza- tion, and both capable of propagating. In the course of making the preceding inquiries after * Notes of the histories of these cases individu- ally were read to a meeting of the Royal Physical Society of Edinburgh in the beginning of 1837. females born co-twins with males in the human subject, we have had a very great number of cases of purely female and purely male twins mentioned to us, who had grown up and be- come married, and in only two or three in- stances at most have we heard of an unpro- ductive marriage among such persons. Further, we may, in conclusion, remark that among the long list of individual cases of her- maphroditism in the human subject that we have had occasion to cite, we find only one instance, (Eschricht's case of transverse herma- phroditism,) in which the malformed being is stated to have been a twin. Katsky, however, Naegele, and Saviard have each, as before stated, mentioned a case in which both twins were hermaphroditically formed in their sexual organs. HERMAPHRODITISM IN DOUBLE MONSTERS. One of the most curious facts in the history of double monsters is the great rarity of an opposite or hermaphroditic sexual type in their two component bodies, the genital organs of both bodies being almost always either both female or both male. Physiological science affords us at present no satisfactory clue to the explanation of this singular circumstance. From two cases of double monstrous embryos observed in the egg of the domestic fowl by Wolff* and Baer,f and from a similar case met with in the egg of the goose by Dr. Allen Thomson, it appears certain that double monsters sometimes originate upon a single yolk, probably in consequence of the existence of two cicatricula? upon this yolk,J or of two germinal points (or two of the vesi- cles of Purkinje and Wagner) upon a single cicatricula. In such a case the two bodies of the double monster are so early and intimately united together as to form, almost from the commencement of development, a single sys- tem ; and therefore the fact of the uniformity of their sexual character is the less remarkable. But in other instances when the double mon- ster originates (as from the phenomena of in- cubation in double-yolked eggs we know to be frequently the case,) on two separate yolks or in two separate embryos becoming fused or united together, at a more advanced stage of develop- ment, it appears more extraordinary that the sexes of the two conjoined foetuses should be so constantly uniform as they seem to be in monsters perfectly double. This uniformity only becomes the more singular when we re- flect that twin children are not at all unfrequently of opposite sexes.§ * Nov. Comment. Acad. Petropolit. torn. xiv. p. 456. t Meckel's Archiv. fur Physiologie, &c. for 1827, p. 576. \ We have in our possession a preparation, taken from a duck's egg, in which two full-grown futuses are developed on opposite sides of a single yolk of the common size. § In the Edinburgh Lying-in Hospital forty-six cases of twins occurred from 1823 to 1836, both years inclusive. In seventeen of these cases the two children were both females ; in sixteen both males ; and in the remaining thirteen instances one child was male and the other female. We know of HERMAPHRODITISM. 737 The fact itself, however we may explain it, of the comparatively extreme rarity of both male and female sexual organs upon double monsters seems sufficiently established by va- rious careful investigations made into the sub- ject. Thus out of forty-two perfectly double monsters which Haller* was able to collect at the time at which he wrote, there were only two that were supposed to be of double sex, or, in other words, that had one body male, and the other female. Among double-headed monsters, with single lower extremities, he found an hermaphroditic type more common, arid adduces three examples of it. In re-investigating this matter, the late Pro- fessor Meckelf could discover among the nu- merous class of monsters with perfectly double bodies united anteriorly or laterally by the tho- rax and abdomen, only one very doubtful case of exception to the above general fact. In the class of double monsters united in the region of the pelvis he mentions two exceptional cases from Valentin'J and IJasenest ;§ of double- headed monsters with single bodies, he quotes three similar eases from Lemery,|| Bacher,5f and Bilsius ;** and of monsters with a single head and double body he adduces two cases from BrissKusff ai1d Condamine,JJ in which in a like manner one body of the monster was supposed to have female, and the other male sexual organs. Several of these cases, how- ever, certainly rest upon too doubtful authority and insufficient observation. Isidore St. Hilaire has still further extended the data on which the above general fact is founded, by shewing that the same uniformity of sex holds good with respect to double para- sitical monsters,§§ and even in monstrosities double by inclusion. Thus out of this last in- teresting class of double monsters, he alludes|||| to ten distinct cases in which the sex of the included being was ascertained. In six out of these ten cases the includingand included body were both male; and in the other four they were both female. On the whole, therefore, we must consider as founded on a proper induction from the ex- isting data, the axiom of Meckel,—" Sexuum diversorum indicia in eodem organismo, quan- tumvis duplicitate peccet, non dari, sed unum tantum observari."H1[ But while all the data hitherto collected with regard to this subject one family in the different branches of which twelve pairs of twins have been born within three generations. In eleven out of these twelve pairs the co-twins have been of opposite sexes. * Opusc. Anat. (1751.) p. 176. t De Duplicitate Monstrosa, p. 21. X Eph. Nat. Cur. Dec. ii. Ann. iii. p. 190. 6 Comment. Lit. Norimb. (1743,) p. 58. || Mem. de l'Acad. des Sc. de Paris, for 1724. t Roux' Jour, de Med. (1788,) p. 483. ** Blankaart's Coll. Med. &c. (1680.) tt Six Observat. de M. Brisseau, (Paris, 1734,) p. 33. V ' ' XX Mem. de l'Acad. des Sc. (1733.) p. 401, $§ Hist, des Anomal. de l'Organiz. torn, iii, pp. 235 and 386. IHI lb. p. 311. ff De Duplic. Monst. p. 21. VOL. II. would seem to point it thus out as one of the most constant and best ascertained laws in te- ratology, still we are not altogether disposed to consider it with Zeviani* and Lesauvagef as subject to no exceptions whatever. In the study of monstrosities, as in the study of other departments of medical science, we find many general, but no universal laws. Bibliography. — Affaitat ( J.), De hermaphro- ditis, Venct. 1549. Columbus, De re anatomica, lib. xv. Venet. 1559. Bauhin ( Caspar ), De her- maphroditorum monstrorumque partium natura. Francof. 1609. Sehenkius ( J. G. ), Monstroium historia meroorabilis, Frankf. 1609. Riolan, Dis- cours sur les hermaphrodites, Paris, 1614. Zac- chias, Questiones medico-legales, lib. vii. Frankf. 1657. Palfyn, Licetus' Traite des monstres. Leid. 1708. Parsons, A mechanical and critical inquiry into the nature of hermaphrodites, Phil. Trans. No. xli. and8vo. London, 1741. Buryhard, Gruend- liche Nachrict von einem Hermaphroditen, Bresl. 1743. Mertrud, Dissertation sur la fameuse her- maphrodite, &c. Paris, 1749. 3Iorand, De her- maphroditis, Paris, 1749. Arnuud, Treatise on hermaphrodites, London, 1750 ; also in Memoires de Chirurgie, torn. i. London and Paris, 1768. Haller, Commentatio de hermaphroditis, et an dentur? in Comment. Societ. Rog. Sc. Gottin- gensis, torn. i. p. 1-26. Gotting. 1752 ; and lb. in his Opera Minora, torn. ii. Lusan. 1764. Guil- tier, Observations sur l'histoire naturelle, &c. p. 16, &c. Paris, 1752. Ferrein, Sur le veritable sexe de ceux qu'on appelle hermaphrodites ; in Mem. de l'Acad des Sciences, 1757. Hunter (J.J, Account of a Free-martin, Philos. Trans. 1779 ; and Animal Economy, p. 55. London, 1792; or in the recent edition by Owen, 1838. Seiler, Observ. nonnul. de Testiculorum Descensu et Part. Genit. Anomalis, Leipzig, 1787. Osiander, Ueber die Geschlechtsverwechselungen Neugeborner Kinder, in his Dcnkwurdigkeiten f ur Geburtshiilfe, Bd. II. s. 462. Gotting. 1795, and in the NeueDenkwurdigk, Bd.I. s. 245. YVrisberg, De Singulari Deformitate Genitalium in puero Hermaphroditum Mentiente, Gotting. 1796; and in his Comment. Medici, Phy- siolog. &c. Argumenti. Gotting. 1800, p. 504-551. Pinel (Ph.), Vices de conformation des parties genitales, &c. in Mem. de la Soc. Med. d'Emulat. torn. iv. p. 234. Paris, 1796. Movreau de la Sartlie, Quelques considerations sur I'hermaphrodisme, ibid. torn. i. p. 243 ; also in his Histoire Naturelle de laFemme, torn. i. p. 211. Paris, 1803. Pietsch, Gedanken von den Zwittern, in the old Hamburgh Magazin. Bd. IV; s. 538. Home ( Ev.J, Dissec- tion of an hermaphrodite dog, and Obs. on herma- phrodites in Philos. Trans. 1795 ; On animals preternaturally formed, Lect. on Comp. Anat. vol. iii. London, 1823. Voigtel, Handb. der Pathol. Anat. Bd. III. Halle, 1805. Achermann, Infantis androgyni hist, et iconog. Jena, 1805. Schuberth, Von Unterschiede der beiden Geschlechtcr, in his Allgem. Gesichte des Lebens. Th. I. Leipz. 1806. Schneider, Der Hermaphtoditismus, in Kopp's Jahrb. der Staatsarzneikunde, p. 193, 1809. Meckel, Ueber die Zwittcrbildung, in Rcil's Archiv fuer die Physiol. Bd. XI. Halle, 1812; Handb. der Pathol. Anat. Bd. II. Leipz. 1816; System der Vergleich. Anatomie, Halle, 1821. Burduch, Metamorphose der Geschlechter, in Anatom. Un- tersuchungen, Leipzig, 1814 ; Physiologie, Bd. I. Leipzig, 1826. Metzyer, Syst. der Gerichtl. Arz- neywiss. Konigsb. 1814. Marc, Bulletin des Sc. Medicales, torn. viii. p. 179 & 245; Articles on her- maphrodites in the Diction, des Sciences Medicales, torn. xxi. p. 36-121, Paris, 1817; and Diet, de Medecine, torn. xi. p. 91, lb. 1824. Steghlener, * Mem. delta Soc. Italian, torn. ix. p. 521. t Mem. sur les Monstr. par Inclusion (Caen, 1829) ; or Archiv. Gen. de Med. torn. xxv. p. 140. 3 c 738 HERNIA. De hermaphroditorum Natura, Leipa. ct Bamb. 1817." Virey, Article hermaphrodite ou Androgyne, in Nouveau Diction. d'Histoire "Naturelle, Paris, 1817. Jacoby, De Mammalibus Hermaphroditis alterno latere in sexum contrarium vergentibus, iierlin, 1818. Lawrence, Article Generation, in Roes' Cyclopaedia, vol. xvi. London, 1819. Feiler, Ueber Angeborne Menschliche Missbildungen, &c. Landshut, 1820. Pierquin, Cas d'hermaphro- disme, Montpell. 1823. Henke, Untersuchungen ueber Hermaphroditen, Gerichtliche Medicin, Berlin, 1824. Penchienati, Observat. sur quelques pretendus hermaphrodites, Mem. de I'Acad. de Turin, torn. x. Rudolph!, Beschreib. einer selt. Menschlichen Zwitterbildung, &c. ; Abhand. der Kdnigl. Akad. der Wissens. zu Berlin fur 1825. Berl. 1828. Lippi, Dissert. Anatomico-Zootomico- Fisiologiehe, &c. Firenze, 1826. Duges, Mem. sur riiermaphrodistne, in Ephemerides Medicales de Montpellier, torn. i. Montp. 1827. Knox, Outline of a theory of herraaphrodism, in Brew- ster's Edinburgh Journal of Science, vol. ii. p. 322. Edinb. 1830. Mutter, Bildungsgeschichte der Genitalien, Dusseldoif, 1830. Gurlt, Lehrb. der Patholog. Anat. der Haus-Saugthiere. Bd. II. Berlin, 1831. Mayer, Icones Selectae prseparat. Mu^ei Anatom. Bonnensis ; Decas Hermaphrodi- torum, p. 8. Bonn. 1831 ; and Walther's and Graefe's Journal, &c. Bd. XVII. Beatty, Article Doubtful Sex, in Cyclopaedia of Practical Med. London, 1833. Beck, Medical Jurisprudence, chap. iv. p. 69-81, Doubtful Sex, London, 1836. Isidore St. Hiluire, Histoire des Anomalies de l'orgauization, &c. Paris, 1836. Barry, On the Unity of Structure in the Animal Kingdom, and in Jamieson's Edinb. New Philos. Journ. for April, 1837. See also the references in the foot-notes. (James Y. Simpson.) HERNIA (in morbid anatomy). The pro- trusion of any viscus from the cavity in which it ought naturally to be contained is termed a hernia, and thus the apparent escape of any part from any of the great cavities of the body may seem to constitute the disease : still, how- ever, as the real existence of cerebral or thoracic ruptures rests upon very doubtful authority and is extremely questionable, and as abdominal protrusions are unfortunately equally palpable and frequent, the application of the term is usually limited to them. To this frequency many causes seem to contribute. In the walls of the abdomen there are three remarkable natural openings, or perhaps it would be more correct to say, there are three situations so weak and unprotected that they easily yield and per- mit the escape of any viscus that may be di- rected against them with even a moderate de- gree of force : these are, the umbilicus, through which during foetal life the umbilical cord passes; the inguinal canal, which allows the passage of the spermatic cord in the male, and the round ligament of the uterus in the female ; and the crural ring, which transmits the great bloodvessels to the thigh and lower extremity. The nature of the walls too, which are princi- pally composed of muscle, and the condition of the viscera within, loose, liable to change of size and situation, and subject to irregular pres- sure by the contractions of these muscular walls, dispose to the occurrence of the disease in any of these situations, where the resistance to such pressure is but feeble. Hence hernia? are most frequently met with at one of the places al- ready mentioned,— the umbilicus and the ingui- nal and femoral canals. But there are other situations* at which protrusions may possibly take place, although fortunately they are infre- quent, such as, at the side of the ensiform car- tilage, at the obturator foramen, at the sacro- ischiatic notch, and between the vagina and rectum in the female. It is also evident that if the muscles or tendons of the diaphragm are wounded, some portions of the contents of the abdomen may escape, thus constituting the varieties of ventral and phrenic hernise. Ac- cordingly the forms of this disease have been arranged and named from the different places at which they occur, — an arrangement of the greatest practical importance ; for as the struc- ture, the size, and shape of each aperture must exert a peculiar influence on the condition of the protruded viscus, on its liability to become incarcerated, on the possibility of its being returned, on the steps to be adopted for this purpose, and above all on the safety and suc- cess of an operation should such be necessary, a knowledge of each of these in connexion with hernia is absolutely indispensable. Besides this division of hernia as to situ- ation, there is another of very considerable im- portance derived from the nature of the viscus displaced: thus in abdominal ruptures the con- tents of the tumour may be intestine alone, in which case it is called enterocele ; or omentum alone, the epiplocel'e ; or both these may be engaged, constituting the enter v-epiplocele. There is not a viscus in the abdomen or pelvis, excepting perhaps only the pancreas and kid- neys, that has not at one time or another formed the contents of a rupture. The stomach has been partially displaced through the dia- phragm, or pushed through the walls of the ab- domen : the duodenum has formed part of a ventral or umbilical hernia : the jejunum or ileum are very likely to be protruded in any situation : the omentum is often displaced, particularly in inguinal hernia; at the left side : the large intestines from being more fixed are not so frequently thrust out, yet the ccecum and colon are but too often found among the con- tents of a rupture. 1 have seen a large portion of the liver in an umbilical hernia of the infant : Verdierf relates numerous cases of hernia of the urinary bladder ; and PottJ mentions one which renders it nearly certain that the ovaria in females may suffer in a similar manner. However, the natural situation of any viscus within the abdomen is but an uncertain cri- terion by which to judge of the contents of a hernia in its vicinity. The strangest displace- ments have been observed occasionally in the examination of this disease : thus the sigm#i^ flexure of the colon- has been protruded at the right side, and the ccecum and valve of th'suleJUTT-. at#the left.* In all large and old hqrni's Hie parts are dragged out of their proper situations, -A ' * \ \ V * Sur plusieurs hemies singulieres. Garengeot, Memoires de l'Academie Royale de Chir. torn. iii. p. 336. Paris edit, in 15 vols. 1771. t Mem. de I'Acad. Royale Je Chir. torn. iv. p. 1. f Pott's Works, by Earle, vol. ii. p. 210. HERNIA. 739 and, their appearances on dissection and rela- tive positions are often such as no one from anatomical knowledge alone could ever have suspected to be possible. In all forms of abdominal hernia excepting those only which immediately supervene on penetrating wounds, the contents of the rupture are lodged within a pouch or bag termed the hernial sue, which is formed of the peritoneum. This membrane lines the entire cavity so per- fectly and completely that nothing can pass out from it without the membrane also participating in the derangement and being pushed out before the displaced viscus. Once formed, this sac is rarely capable of being replaced or returned into the cavity of the abdomen ; never unless the hernia is small and recent, and " the cel- lular substance accompanying it and the sper- matic cord through the ring has not lost its natural elasticity and contractility." * Many surgeons have doubted the possibility of such an occurrence at any period,-)- but the fact has been demonstrated by dissection, and still more forcibly by the circumstance of the hernia having been thus strangulated within the ab- domen when the sac has been returned along with it. However, as I have said, the sac when once formed is rarely capable of being replaced, nor does it long remain in this abnormal situation without undergoing some change in its patho- logical condition — a change which it is not always easy satisfactorily to explain. In small hernia? that have recently come down, the struc- ture of the sac differs in nothing from that of the abdominal peritoneum ; and if the rupture is not reduced or kept up by a truss, it will pro- bably increase in size without any remarkable alteration of tissue, for the membrane is ex- tremely distensible, and will accommodate itself to any quantity of contents. But, if the hernia is carefully kept up, there can be no doubt that the sac will gradually contract and seem to rise up and approach the opening through which it originally passed, so that, although its cavity is never completely oblite- rated, it is palpably diminished in size, and in- capable of receiving and retaining the same quantity of contents it originally held. Some- times in old and neglected herniae the sac seems to become so thin that the peristaltic motion of the intestines within it has been clearly perceived : this most frequently occurs in umbilical hernia, and is one of the reasons why this form of rupture was supposed not to have been enveloped in a sac at all. Again, on the contrary, in old herniae also, and particularly where bandages have been worn to support or compress the tumour, it seems to become very tnick, strong, and tense, and is said to have been met with as tough and as thick as cartilage. But in the great majority of instances these changes are rather apparent than real, and though^doubtloss the structure of the sac is no longer exactly that which it possessed before protrusion, the alteration is not so great as * Scarpa on Hernia, translated byWishart, p. 68. t See Louis, Mem. de l'Acad. Roy. de Chir. torn. ii. p. 486. some writers have supposed. It was the opinion of Scarpa that an old hernial sac is in reality but slightly if at all thickened, and that the apparent thickening is caused by the con- densation of the cellular tissue external to and around it. And here I may remark that diffe- rences of opinion as to the altered structure of the sac may have arisen from a difference of accuracy and minuteness in examination, either during the progress of an operation or after death. We shall find hereafter that the normal anatomy of the parts connected with hernia is largely indebted to the knife of the anatomist for the shapes of the different openings, the division and enumeration of the different layers of fascia, and many other points; but in the morbid anatomy of the disease the same patient investigation and the same accuracy of descrip- tion has not been so uniformly observed, and hence our knowledge of the latter part of the subject as compared with the former is by no means so defined and exact. Where a rupture has been a long time down, it is not probable that the intestine shall thus remain in an abnormal situation without occa- sionally suffering from inflammation, and hence adhesions between it and the sac are by no means unfrequently formed : the same effect may be produced by accidental violence, or from the latter cause the sac may be ruptured and its contents left lying under the usual coverings independent of the peritoneum. This is another of the cases in which a hernia has been supposed to exist without the invest- ment of a sac. The peritoneal aperture leading from the cavity of the abdomen into that of the rupture is narrow, and is called the neck of the sac : its dimensions as to length, however, vary with circumstances. As long as the communication is open and free between the two cavities, all that portion of peritoneum which is placed between them and corresponds to the canal through which the rupture has passed, may be termed the neck, and thus in inguinal hernia may be an inch, and in crural half an inch in length. But when the protruded parts are strangulated, the little circle only around which the compression directly operates is more pro- perly entitled to the appellation, and its extent is seldom greater than two lines. When the neck of the sac of a very recent hernia is viewed from the cavity of the abdomen, the peritoneum in its vicinity is seen thrown into slight folds or plaits, which appear to be prolonged downwards into the tumour; but on slitting open the neck, I have never seen this appearance within it, the membrane there being smooth, rather whiter and more opaque, and evidently thicker and more uryielding than elsewhere. If such a hernia in the living subject has been reduced and kept up by la truss, the neck gradually contracts under the pressure, and iis diameter with re- spect to that of the ring tnrough which it has passed is altered to a degree that is of the greatest importance in the event of another pro- trusion, for it will be shewn hereafter that such a diminution of size greatly predisposes to the occurrence of strangulation. It is also possible 3 c 2 740 HERNIA. that the neck shall be so contracted that in the new occurrence of hernia an additional portion of peritoneum may be detruded, and then the sac must present the shape of an hour-glass, narrow in the centre and broad at either end : sometimes two, three, or more of these succes- sive protrusions take place, and then the sac is divided into so many sacculi with incomplete intercepts or partitions between them. Or one portion of peritoneum may be forced within another, so that the intestine is actually in- cluded within a double sac. This last is a curious and very uncommon occurrence. On the other hand the neck of a hernial sac may suffer distension. In very old ruptures that have become irreducible or from any other cause been long down, the neck of the sac sometimes becomes wonderfully dilated, and the portion of intestine immediately passing through it scarcely subjected to the slightest pressure. There is one form of hernia, the chief peculiarity of which lies in the nature of its peritoneal investment, for, correctly speaking, it possesses no proper sac. It is the hernia con- genita,* a species of rupture which occurs in very young infants, and sometimes, under peculiar circumstances, in persons of a more advanced age also. During the early periods of foetal existence the testes do not occupy that situation which they possess in after life. They are placed ■within the abdomen, above the pelvis, which at this time is so small and imperfectly developed that many of the viscera lodged within it after- wards, seem now to lie within the belly. They are just below the kidneys, in front of the psoas muscle at each side, and possess, like other viscera, an investiture of peritoneum, which is afterwards to be the tunica vaginalis testis. About the sixth month, or perhaps the seventh or even later, (for it observes no exact rule in this respect,) the testis begins to descend, not gliding behind theperitoneum, but preservingits own investing coat until it comes to the internal abdominal ring, where it pushes a process of peritoneum out before it, just as an intestine would do in the production of a hernial sac. This is afterwards to become the tunica vaginalis scroti. The testicle then passes on through the inguinal canal, through the external ring,f and finally drops into the scrotum. After some time the canal of communication with the cavity of the abdomen begins to contract and close, and if the usual process goes on healthily and without interruption, very shortly a complete obliteration takes place, and the testis is sepa- rated from the abdomen perfectly and for ever. The time at which this is accomplished is ex- tremely uncertain : sometimes it is perfect at birth ; in other cases the canal is more or less open, and then, if the infant cries or struggles, a portion of the contents of the abdomen is protruded into the cavity of the tunica vaginalis, * Hunter's Animal (Economy. + Sec some observations on the descent of the testicle by the late Professor Todd, of Dublin, in the 1st vol. Dublin Hospital Reports. See also Hey's Observations in Surgery, p. 226. and the hernia congenita is formed. If any part of the above-mentioned process is interrupted or postponed, it will occasion some variety. Thus the tunica vaginalis may not exhibit its usual disposition to close and become obliter- ated at its neck, and then for a length of time the patient is exposed to all the inconvenience and hazard of the descent of a hernia: sometimes the testicle does not come down until a much later period, a circumstance that is often occa- sioned by the gland contracting adhesions with some adjacent viscus in its passage, and may be attended with the additional inconvenience of drawing down such viscus along with it. The surgeon should also be aware of the possibility of the protrusion of another portion of perito- neum into the open tunica vaginalis, and thus a mixed case may arise of a congenital containing within it a proper sacculated hernia. The congenital rupture, then, has no proper sac, but is lodged within the tunica vaginalis in close apposition with the testis : hence many of its peculiarities can be explained. It is obviously the only kind of hernia in which an adhesion can exist between the testicle and the protruded viscus, and it is also evident that the testis does not bear the same relation to the protruded viscus in this that it does in cases of ordinary rupture. Here it is higher up, and seems to be more mixed and identified with the other contents; the entire tumour is more even and firm, the protruded parts are less easily felt and distinguished; and Hesselbach states that when strangulation is present, the sac is every where equally tense, and the testis cannot be felt at all. In very young infants a small quantity of fluid is often present along with the intestine in the tunica vaginalis : it disappears when the child is placed in the recumbent posi- tion, and does not add to the difficulty or im- portance of the case. It has been stated that the tunica vaginalis has a natural tendency to become closed at its neck, and therefore is it more likely to thicken and diminish in capacity in this situation so as to form a band round the protruded viscus. Pott* was of opinion that congenital hernia was more subject to be con- stricted at the neck of the sac than any other : Wilmer stated that out of five cases of congen- ital hernia on which he operated, three were strangulated at the neck of the sac; and Sandi- fort and others maintained the same doctrine. Scarpaf thought that every displaced portion of peritoneum possessed the same tendency to contraction, and advanced it as a reason why stricture in the neck of a hernial sac should be more frequent in all kinds of hernia than is generally supposed. It is not easy to place implicit reliance on this latter opinion, because the neck of the common hernial sac when once formed is never again completely closed ; but with respect to congenital hernia the observa- tion appears to be equally correct and im- portant. Scarpa} describes a form of hernia which may * Pott, op. citat. p. 184. t Page 131. $ Op. citat. p. 205 et seq. HERNIA. 741 under certain circumstances of imperfect or care- less examination appear to be devoid of a proper sac, formed by a descent of the peritoneum. This occurs at the right groin, is always large, and is formed by a protrusion of the ccecum with the appendix vermiformis and the begin- ning of the colon. The coscum is placed in the right ileo-lumbar region, and a portion of it does not possess a peritoneal covering, but lies abso- lutely without the great abdominal membranous sac: when therefore these parts are protruded, a portion of the ccecum and the beginning of the colon will be found included and contained in the hernial sac, while another portion of the same intestines will be necessarily without the sac, and lying denuded in the cellular substance which accompanies the descent of the perito- neum in the hernia. If this tumour is opened into by an incision carried too much towards its external side, the ccecum and colon will be exposed lying outside of the peritoneum, and ap- parently devoid of a hernial sac; but if cut into precisely in the middle or a little towards the inner side, under the cremasler muscle and the subjacent cellular tissue, the true hernial sac will be found, formed of the peritoneum. Within this will be seen " the greater portion of the ccecum with the appendix vermiformis, and likewise the membranous folds and bridles which seem to be detached from the hernial sac to be inserted into these intestines, the smaller portion of which will be without the sac, in the same manner as when these viscera occupied the ileo-lumbar region." This form of rupture I have never seen, and must there- fore refer the reader to Scarpa's work, wherein he will find the peculiarity most satisfactorily explained. But in the arrangement of herniae, that di- vision is most practically interesting which has reference to the condition or state of the intes- tine or other protruded viscus, and the disease is then described as being reducible, or irredu- cible, or strangulated. 1. A hernia is said to be reducible when it either retires spontaneously on the patient as- suming the recumbent posture, or can be re- placed without difficulty to the operator or future inconvenience to the patient beyond that resulting from the employment of measures adapted to retain it within the cavity. This condition supposes that the relation (particu- larly as to size) between the hernia and the aperture through which it had escaped has not undergone any alteration. 2. It is irreducible when there is such a change in the structure, situation, or other con- dition of the protruded viscus as to render it impossible to be returned, although the aper- ture through which it passed may offer no im- pediment. There is another case in which a hernia has been considered irreducible, namely, when it would be impolitic or unwise to attempt the reduction, supposing it to be perfectly practicable. 3. A hernia is strangulated when the relation as to size between the protruded viscus and the aperture through which it has passed is so altered as not only to prevent reduction, but to cause such a degree of compression at the aperture as will interrupt the circulation through the escaped viscus, and endanger its vitality. This condition has been supposed to exist in two different forms, strangulation by inflammation and by " engouement,"* or as Scarpa terms them, " the acute and chronic ;"f but this division only has reference to the severity of the symptoms aud to the rapidity or slowness of their progress, for although an intestine may be in a state of obstruction which will, if unrelieved, proceed to strangulation, yet the latter state cannot be said to have arrived until the return of the venous blood from it is actually impeded. The protruded viscus is then in a situation precisely similar to that of a limb round which a cord had been tied with sufficient tightness to interrupt the circulation and threaten to induce mortification. These different conditions will be best under- stood by tracing a rupture through each of them in succession. A person may be suspected to have a reduci- ble hernia when, after the application of some force calculated violently to compress all the viscera of the abdomen, an indolent tumour appears proceeding from some of those places where the walls of the abdomen are Known to be weakest and least resisting. And the sus- picion is increased if the tumour is elastic, if it sounds clearly on gentle percussion, and becomes suddenly puffed up and swelled, as if by air blown into it, when the patient coughs, sneezes, or performs any of those actions which forcibly agitate the abdominal parietes. The reducible hernia becomes smaller or .perhaps disappears altogether when the patient lies down : it appears of its full size when he stands erect ; if neglected, it has a constant tendency to increase, which it does sometimes by de- grees, slowly and almost imperceptibly, but more frequently by sudden additions to its bulk, which are formed by new protrusions. In this form of the disease the qualities of the viscus engaged within the sac, as to form, size, and structure, may be considered as unchanged : within the abdomen, however, the fold of mesentery which supports the protruded intes- tine is constantly more elongated than it natu- rally should be, and likewise thicker and more loaded with fat. It is also marked with dilated and tortuous veins. Although thus displaced, the viscus is_ still capable of performing its part in the function of digestion, and as long as the contents of the bowel pass fairly and uninterruptedly through it, there can be little or no danger; but it is not difficult to conceive how a gut so circum- stanced may occasion great inconvenience. The peristaltic motion must be more or less impaired ; the passage of the contents may be delayed, and hence will arise nausea, colicky pains, eructations, and those other dyspeptic symptoms from which even the most favoured patients do not escape. These irregularities * Goursaud, Mem. del' Acad. Roy. de Chir. torn, ii. p. 382. t Op. cit. p. 290. 742 HERNIA. again can scarcely exist for any length of time without producing some inflammation, and thence it follows that it is rare to meet with an old hernia in which adhesions have not formed either between the intestine and the sac, or between the convolutions of the protruded viscera, circumstances that must render it im- possible to replace the hernia, or supposing it replaced by force, will be likely to occasion incarcerations within the cavity of the abdomen itself. These adhesions, as discovered either during operation, or by dissection after death, are of different degrees of closeness, firmness, and tenacity, and have been arranged under three classes, the gelatinous, the membranous, and the fleshy. "The gelatinous adhesion, a very general consequence of the adhesive inflammation which attacks membranous parts placed in mutual contact, is only formed by a certain quantity of coagulable lymph, effused from the surface of the inflamed parts, which coagulating assumes sometimes the appearance of a vesi- cular reddish substance stained with blood, sometimes of threads or whitish membranes easily separable from the parts between which they are interposed and which they unite to- gether, without any abrasion or laceration being produced by the separation, on the surface of the parts agglutinated together."* This kind of adhesion being the result of recent inflam- mation can rarely be met with in operations performed for the relief of strangulated hernia, for the condition of a viscus so engaged is that in which such an effusion would be unlikely, if not impossible. Its vessels are loaded and congested with venous blood : there is effusion of serum to a greater or less quantity, as is seen in every instance of obstructed venous circu- lation ; and if there is recent lymph, it must be owing to the fortuitous circumstance of the viscus having been inflamed immediately before it became strangulated. In a vast number of cases operated on, I have seen but one instance of the existence of this soft adhesion, and in that the hernia was not strangulated : it was a case (such as is related by Pott) of inflammation affecting the intestines generally, in which those within the hernial sac, of course, participated. The membranous and fleshy adhesions are the results of former attacks of inflammation, and are exactly similar to those attachments so frequently met with between serous surfaces in other situations. When the opposed surfaces lie motionless and undisturbed, their connexion is firm and fleshy, and hence this kind of adhe- sion is seen at the neck of the sac, between the omentum and the sac, and occasionally between the intestine and the testicle in congenital hernia; whilst between the convolutions of the intestine itself, or between it and the sac, any union that exists is more generally loose and membranous. Besides adhesion, there are many other causes that may render a hernia irreducible, one of the most prominent of which is the patient's neglect in leaving the hernia down, * Scarpa, p. 180. and the alterations in shape and structure that thence ensue. In such case, the parts within the tumour, as the mesentery and omentum, have room to increase, whilst at the mouth of the sac they remain constricted and of their natural size, though condensed and solidified in structure. This happens particularly with the omentum, which becomes hard, very dense, and compact, and not unfrequently resembles a fibrous structure covered by a fine smooth membrane, and then there is within the sac a tumour actually much larger than the aperture it would have to pass, and through which no force could be capable of pushing it. It may happen that the part of the omentum which is below the stricture shall remain loose and expanded, and enjoy its natural structure, whilst that which is lodged within the neck of the sac is compressed and hardened, in which case the hernia will probably prove irreducible. It sometimes happens that scirrhus of the intestine renders a hernia irreducible. Such a malignant alteration of structure is by no means frequent in the intestinal tube — certainly far less so than in the omentum, but the possibility of the occurrence is proved by a case under my own immediate superintendence. The patient had a large hernia which he had been able occasionally to reduce, but which was usually left down. On a sudden he was attacked with symptoms of strangulation, small quick pulse, tenderness of the abdomen, acute pain in the tumour, constipation, general low fever and fcecal vomiting. The operation was performed, and the cause of the symptoms found not to have been in the situation of the neck of the sac, which was more than commonly open and free, but in a scirrhus of one of the lesser intestines.* The form of hernia already noticed as being apparently devoid of a sac has been mentioned by Pottf as one peculiarly difficult of reduc- tion. " They have consisted of the coecum with its appendicula and a portion of the colon. Nor," continues this distinguished surgeon," will the size, disposition, and irregular figure of this part of the intestinal canal appear upon due consideration a very improbable cause of the difficulty or impossibility of reduction by the hand only." The last circumstance to be considered as rendering a rupture irreducible is the absolute size of the tumour and the quantity of viscera it contains. It is amazing to what extent the contents of the abdomen may be protruded from it, and the patient nevertheless enjoy a state of health that might be called good, so far as the annoyance of such a tumour could warrant the expression. Every surgeon must have heard of hernia? in which all the loose intestines were protruded, and in fact every thing that could with any degree of probability be supposed to have been capable of being pushed from the cavity of the abdomen. I * The preparation of this interesting case is in the Museum of the Medico-Chirurgical School, Park Street, Dublin. f Pott, op. cit. p. 24. HERNIA. 743 have seen and dissected a case of this descrip- tion in which the tumour during life reached to within two inches of the knee, and obliged the unfortunate subject of it (who was a lamp- lighter) to wear a petticoat instead of breeches. Similar instances are not very unfrequent, and it is obvious that an attempt at reduction here would be injudicious even if it was practicable. It is the nature of all hollow structures in the body, whether cavities or vessels, to accommo- date their size and capacity to the quantity of their contents, and the cavity of the abdomen will, under such circumstances, become so con- tracted as to be either incapable of immediately receiving the protruded viscera again, or else the sudden distension will excite peritoneal inflammation — an evil greater than the existence of the hernia. These latter, however, cannot be regarded as permanently irreducible, for Arnaud, Le Dran, and Hey have succeeded in gradually restoring them by means of a bandage shaped like a bag, which being laced in front admitted of being tightened still as the tumour diminished. The last and most fearful condition of a rup- ture is its state of strangulation, in which the protruded viscus, no longer capable of being returned to its former situation within the ab- domen, no longer fit for the performance of its functions, is banded and bound down at its neck in such wise as to interrupt and impair the circulation through it. In order properly to understand this part of the subject, it will be necessary to consider it under three heads: — 1. the causes that seem to produce the stran- gulation ; 2. its effect on the structures within the hernial sac ; 3. its effect on the viscera within the cavity of the abdomen. 1. Of the three natural apertures at which abdominal hernise commonly occur, one, the umbilicus, is unquestionably seated within tendon, and so circumstanced that any con- traction of any muscle connected with it, whe- ther spasmodic or permanent, must rather ex- pand the opening than contract it. Another, the crural ring or canal, is composed of tendon and of bone, and so constructed that although certain positions of thp trunk or inferior extre- mity might possibly diminish its size, no mus- cular action can exert any influence over it. The third, the inguinal canal, is of greater length and more complicated in its construction, and it is a question whether the same pathological condition can be predicated of it, or whether strangulation does not here occasionally occur in consequence of muscular action alone.* Sir A. Cooper seems to acknowledge the possibility of a spasmodic stricture at the internal ring, the strangulation then being effected by a com- pression exercised by the inferior edge of the internal oblique and transversalis muscles.-f Guthrie speaks of hernia? being frequently strangulated by passing between the fibres of the internal oblique, which are separated at the inferior and external border of the muscle above the origin of the cremaster.* Scarpa says that " towards the side, at about eight lines distance from the apex of the ring, the lower muscular fibres of the internal oblique muscle separate from each other to allow the spermatic cord to pass between them:"f and again, " the small sac or rudiment of the hernia, not unlike a thimble, when it makes its first appearance under the fleshy margin of the transverse, rests immediately on the anterior surface of the spermatic cord ; it then extends and passes in the middle of the separation formed by the divarication of the inferior fleshy fibres of the internal oblique and of the principal origin of the cremaster muscle."]: It must, however, be conceded that Scarpa did not attribute the strangulation of any form of inguinal hernia to a contraction of these muscular fibres. Now, although it is almost presumptuous to differ from authorities of so high a class, yet I cannot agree either with the opinion that hernise are liable to a spasmodic constriction, or with the descriptive anatomy on which such an opinion might be founded. In about one subject out of every three or four there certainly is a slight divarication or separation of fibres of the external oblique muscle, or rather there is a cellular connexion between the origin of the cremaster muscle and the inferior fibres of the oblique, which is easily separable by the knife; but the question is, does the spermatic cord in the natural condition, or the hernia in its course to the external ring, pass through or between these fibres ? I believe they do not. I have dissected numerous cases of hernia without observing such a disposition of parts, and I think that if either the spermatic cord or the hernia took such a course, the pro- trusion must then come to lie in front of the cremaster muscle — a position that has not been hitherto observed. When a hernia is found at the groin, the tendon of the external oblique is somewhat stretched and arched forwards above Poupart's ligament in front of the inguinal canal : the fascia transversalis maybe stretched also, and the epigastric artery pulled out of its place and made to approach the linea alba; but the muscles arising from Poupart's liga- ment, the internal oblique and transversalis, re- main unchanged, and if ever strangulation is effected through their operation it is in the manner suggested by Sir A. Cooper. But it is more simple and perhaps more scientific to place muscular contraction out of the question altogether. The phenomena of strangulation exhibit nothing like the irregularities of spasm: there is no sudden exacerbation, no succeeding relaxation — no alternation of suffering and re- lief, no assuagement of symptom from medi- cines decidedly antispasmodic; I he disease once established goes on with an uninterrupted and certain progression that will not admit of expla- nation by a cause so irregular as spasm. But it is unnecessary to resort to an expla- nation which might prove so practically dan- * See the anatomy of inguinal and femoral hernia in a future part of this article, f Cooper on Hernia, p. 21 . * Guthrie. t Scarpa, op. cit. p. 27. t Ibid, p. 50. 744 HERNIA. gerous, because the existence of strangulation with all its fearful sequelae may be proved, in situations and under circumstances where the influence of spasm or of muscular action is ob- viously impossible. Thus intestines have been found strangulated within the cavity of the ab- domen itself, as when a fold of intestine has passed through an accidental opening in the mesentery or the omentum, or when artificial bands or nooses have been formed by lymph, the products of former inflammation. Scarpa relates a very interesting case in which he found that the appendix vermiformis surrounded in the manner of a ring and strangulated a long loop of the ileum just before its insertion into the colon. If it be conceded that the natural openings at whicli abdominal herniae occur are composed either of tendon or of tendon and of bone, and therefore are not subject to accidental variations of size from irregular muscular action, it would seem on a prima facie view that wherever any substance had passed out it ought to be able to return, provided an equal degree of force is employed with that which originally caused the displacement. And this actually does take place, for the hernia returns spontaneously or is easily reduced as long as the original propor- tion between the size of the protruded part and that of the aperture remains unaltered. Again, as long as this relation is maintained, the cir- culation through and from the protruded viscus will continue equable and healthy, but an in- testine from its structure and its functions is extremely liable to a change of size, and when that happens, the proportion no longer exists, and the hernia begins to become incarcerated. If not relieved, the protruded viscus continues to swell, and is thus made to form an acute angle at the spot where it escaped, which tightens the ring of intestine immediately at the neck of the sac : the return of the venous blood is thus prevented ; the swelling then increases until not even gas can pass through, and then strangulation is complete. In this way a number of circumstances connected with hernia can be explained. If the ring is small, a very trifling change of size in the protruded part will be sufficient to cause strangulation : hence crural hernia is more liable than inguinal, and very recent ruptures in which the ring is of its natural size than those of long standing, in whicli that aperture is probably enlarged. Persons who are formed with large rings, and thus possess an hereditary disposition to hernia, are less liable to strangulation : this may ex- plain Pott's remark that " if the hernia be of the intestinal kind merely, and the portion of the gut be small, the risk is the greater, stran- gulation being more likely to happen in this case ;" for assuredly if the ring is so small as to permit only the escape of a knuckle of intestine, a very trifling change in the latter will be suffi- cient to establish a disproportion between them. Again, if a hernia has come down, and been reduced, and kept up until the neck of the sac has been diminished in size, and if afterwards a protrusion takes place, a very trifling alteration in this latter will render it incapable of return, and explain why such her- niae are so frequently strangulated at the neck of the sac. Hence it appears that a straitness or tightness at one of the rings may be a predis- posing cause of strangulation, that is, may be a reason why one hernia should become sooner strangulated than another, but the immediate or efficient cause is a change in the condition of the viscus itself. Thus when a loop of in- testine is gangrened, and its contents have escaped totally or partially into the sac, the hernia often returns spontaneously, the parts in the immediate neighbourhood of the ring re- maining unaltered. Also if such a hernia is the subject of operation, there is no necessity for dilating the seat of the stricture : indeed Louis forbids the practice lest some essential point of adhesion should be destroyed. "Di- latation," says he, " is only recommended in order to facilitate the reduction of the strictured parts. In the gangrened intestine there is no reduction to make, and there is no longer strangulation, the opening in the intestines having removed the disproportion that had existed between the diameter of the ring and the volume which the parts had acquired; and the free passage of the excrement which the sphacelus has permitted removes every symptom that depends on the strangulation."* In like manner may be understood why omental her- niae are less liable to become strangulated, be- cause this structure is not subject to any sud- den change of shape or increase of volume : when it does occur, the progress of the disease is more slow, and the symptoms are said to be less severe. The division of herniae into the incarcerated and strangulated, or into the acute and chronic forms of strangulation, however practically valuable if it inculcates a different mode of treatment for these affections, is yet pathologi- cally incorrect if it supposes any analogy be- tween them and the acute and chronic species of inflammation. An incarcerated hernia is not strangulated ; it is really in a condition re- sembling irreducibility. I have before stated that in large and old herniae the neck of the sac generally becomes enlarged, and of course such a change of dimensions in the protruded viscera as is necessary to cause their strangulation will be proportionally less likely to occur. But hard and unwholesome and indigestible sub- stances may gain admission into some of them and lodge there, for it must be recollected that the process of digestion cannot be very favora- bly carried on in intestines thus protruded, placed in positions that will render it necessary that their contents must ascend against the in- fluence of their own gravity, and deprived of the salutary pressure exercised by the walls of the abdomen on the viscera within it. If such a lodgment is formed, it will be the cause of future accumulation, and may occasion a deter- mination of blood to the part or even inflam- mation within it, thus gradually increasing its volume and leading it to a state that must end in strangulation. Undoubtedly, if the dura- * Mem. de l'Acad. Roy. de Chir. torn. viii. p. 45. HERNIA. 745 tion of such a case is reckoned from the first occurrence of symptoms, which at that period are only those of indigestion, it will be an ex- ample of a very chronic case of strangulated hernia ; but these two stages of the disease ought to be distinguished, for the treatment that would be judicious in the one might be injurious or destructive in the other. The in- carceration of a hernia does not, moreover, ne- cessarily involve its eventual strangulation, and this constitutes a vast difficulty in the case, for on the one hand few surgeons will advise an operation until there is an obvious and decided necessity for it, and on the other it is quite possible in a case of this description that the symptoms shall never be urgent, and yet the intestine be found in a state of actual sphace lus. I have seen a patient operated on in whom the hernia had been down and the bowels constipated for eighteen days. The intestine was completely mortified. That strangulation which is most rapidly formed is the most severe in its symptoms and the most dangerous in its consequences, but between these extremes there is every possible degree of intensity. A hernia has been gan- grened in eight hours after protrusion. Mr. Pott frequently mentions a single day as caus- ing a most important difference in the case, and 1 have found an intestine sphacelated on the day following the first occurrence of the dis- ease ; however, in general the case is not so quickly decided, although every moment of its duration is pregnant with danger. The change that is effected in the strangulated viscus next demands attention. Its altered condition has been always spoken of under the name of in- flammation,* not from want of a perfect and accurate knowledge of its pathology, but pro- bably from the term appearing convenient and being hastily adopted by one writer from ano- ther. Yet as it is not inflammation, the name is incorrect, and perhaps it has been injurious in leading practitioners to attempt a mitigation of the inflammation in the tumour, instead of the more obvious indication, a diminution of its size. The volume of a strangulated intes- tine is always increased. In small hernias (which in this respect can be more accurately examined) the intestine, on the sac being divi- ded, starts up and swells out as if relieved from a compressive force. It always contains air, and if cut into, a small portion of dark-coloured serum will generally escape. Its colour, which is manifestly occasioned by an accumulation of venous blood, is at first of a reddish tint of purple, soon however changing to a coffee ' * "The inflammation that takes place in stran- gulated hernia is different from almost every other species : in most cases it is produced by an unusual quantity of blood sent by the arteries of the part, which become enlarged ; but still the blood returns freely to the heart, and the colour of the inflamed part is that of arterial blood ; whilst in hernia the inflammation is caused by a stop being put to the return of the blood through the veins, which pro- duces a great accumulation of this fluid, and a change ot its colour from the arterial to the venous hue.' Cooper on Hernia, p. 20. brown, and there is always more or less of serum within the sac, as in every other case of venous congestion. If unrelieved, dark and fibrous spots appear which are truly specks of mortification ; they very soon separate and allow a discharge into the sac of a quantity of putrid fjeces and horribly fetid gas. This done, the intestine either remains collapsed within the sac, or retires spontaneously into the abdomen. In the meantime the parts covering the hernia become inflamed; in the first instance probably from sympathy with the deeper struc- tures, afterwards obviously as an effort of nature to get rid of the putrid and sphacelated matter underneath. In the early stages the local symp- toms are seldom very severe: the tumour is scarcely painful, and will permit reiterated at- tempts at the reduction of the hernia, and en- dure considerable pressure, whilst the abdomen may not be touched without intense suffering. In a little time, however, it becomes tense and tender to the touch, red, oedematous, and pitting under the finger, which leaves a white impres- sion for a moment after it has been withdrawn. In fact, it is erysipelatous inflammation attack- ing the coverings of the hernia, and its approach is often accelerated by handling the tumour or by repeated injudicious attempts to reduce it. This (if the patient lives sufficiently long) always terminates by the formation of one or more sloughs, on the separation of which the putrid coverings are thrown off, and the contents of the bowels being evacuated, the patient's life may be saved, but with the inconvenience and danger of an artificial anus at the groin. It is seldom that the efforts of nature are thus ca- pable of procuring relief, the contents of the rupture being generally sphacelated, and incu- rable mischief effected within the abdomen long before its external coverings shew anv dis- position to burst spontaneously. I think the condition of the sac has some influence on this external inflammation. In all cases it under- goes a less injurious alteration of structure than the intestine contained within it, and is often found comparatively sound while the latter is in a state approaching to sphacelus. The supe- riority of its vascular organization, its containing a greater quantity of blood, and moreover the volume of air always contained within the bowel, will explain this pathological difference; but the sac itself sometimes suffers from con- gestion to a greater or less extent, and this, of course, in proportion to the degree of con- striction fixed upon its neck. An old hernial sac, the neck of which is thickened and ac- customed to its new position, and which is itself probably one of the chief causes of the stricture, will be less likely to suffer from an interrupted circulation than a recent protrusion just forced out through a narrow undilated ring. It is in this latter case that the external structures ought to be the soonest engaged, and it has been in recent and acute cases of hernia that I have seen the earliest examples of super- ficial inflammation. 3. Such, during the progress of a hernia, is the condition of the parts more locally engaged; 746 HERNIA. but a far more serious because a more fatal process is going forward within the abdomen. It must be recollected that a gangrene of the intestine when out of the abdominal cavity is not necessarily fatal ; that the gut may die and putrefy, and be thrown off by the results of external inflammation and sloughing, and yet the patient live for many years with an artificial anus, or even have the natural passage per anurn restored again. Numberless cases of artificial anus have thus occurred, not one of which could have been saved if the sloughing of the intestine was inevitably mortal. But soon after the strangulation is effected, either from the pressure on the viscus, which may be sup- posed to have a material influence, or from the mechanical obstruction to the passage of the feces, inflammation is established within the cavity, commencing probably at the strictured spot, and spreading thence with great rapidity. The part of the peritoneum most engaged is that which covers the line of intestine inter- posed between the stricture and the stomach ; the least, that which invests the walls of the cavity. This inflammation may be in part salutary, for it occasionally causes an adhesion of the intestine at the neighbourhood of the ring so firm that it cannot be removed there- from, and thus provides for the occurrence of an artificial anus subsequently without the danger of any internal effusion ; but unless the stricture is relieved at this time, and a check thus given to the progress of the disease, the intestines become matted with lymph, effusions are poured out of a similar nature to those that occur in other forms of peritonitis, and the patient dies — not of the gangrene of the pro- truded intestine, but of the peritoneal inflam- mation within. On opening the body of a person who has thus died, the intestines above the stricture are found inflamed, of a red or pink colour, greatly distended with flatus and perhaps with fecal matters ; below the stricture they are inflamed also, but remarkably diminished in size. There is always an effusion of lymph to a greater or less extent glueing the convolutions of the bowels together, and there is often on the sur- face of the peritoneum not covered with lymph, a dark appearance as if blood was ecchymosed beneath it. Effusions are also constantly met with, sometimes apparently of pure pus, diffused, particularly throughout the spaces formed by the apposition of the convoluted intestines, sometimes more abundant, and con- sisting of serum mixed with lymph in loose and floating flakes ; and occasionally a more gelatinous substance is observed very much re- sembling the jelly-like material that surrounds frog-spawn in stagnant ponds. I have never met the existence of gangrene within the ab- domen in any case of death from strangulated hernia. The line of intestine, then, within the ab- domen, and the loop within the sac, are diffe- rently circumstanced. Above the stricture there is active inflammation exactly such as might occur idiopathically, presenting the same morbid appearances, and accompanied by a similar train of symptoms : below, there is a state of venous congestion in which the vessels endeavour to relieve themselves by pouring out a serous effusion, and in which gangrene super- venes with a rapidity proportioned to the tight- ness of the constriction. Between these, and immediately under the stricture, it is white, pale, and bloodless all round for the spaee of two or three lines, and appears to be diminished in size more than it really is on account of the great enlargement immediately above and below. The condition of this strictured ring of intestine is of the utmost importance in the progress of the case, for it is not uncommon for it to ulce- rate or to slough under the influence of the continued pressure. I have seen an operation admirably performed, and the intestine returned under apparently favourable circumstances, yet the patient sink and die in the course of a few hours : a small hole existed in the con- stricted spot, through which fecal matter had escaped and become diffused within the cavity. In another instance, from the anxiety of an operator to inspect the condition of this spot previous to the return of a hernia, the intestine in the act of being drawn out tore almost as easily as a wetted rag. It will not be difficult to connect the symp- toms of this disease with the morbid alterations just described. When a hernia is about to become strangulated, the earliest symptom is in general pain, at first referred to the seat of the stricture, but soon becoming diffused over the abdomen, when the chief suffering is often seated in the region of the navel. The belly then becomes hard and tense, at first rather contracted, but subsequently swollen and tym- panitic : it is exquisitely tender to the touch, cannot endure the slightest pressure, and in some cases even the contact of the bed-clothes is intolerable. The patient lies in bed with his legs drawn up, and if possible his shoulders bent forward on the trunk ; he cannot without excessive torture endeavour to move himself in any direction, and a moment in the sitting pos- ture is not to be endured. Of course when the whole canal of the intestine is constricted, there must be constipation of the bowels ; yet cases have been mentioned in which, though all the other symptoms of strangulated hernia were present, the discharges from the bowels have not ceased, — a circumstance that has been explained by the supposition that only a por- tion of the circumference of the intestine was engaged. I believe, however, that most of these cases were delusive, and that when the alvine discharges have continued to a very late period, the case was one of incarceration in which peritoneal inflammation may not be established for a long time or perhaps at all ; or else the practitioner was deceived by some of those discharges from the line of intestine below the stricture which are so frequently brought away by the administration of enemata. The explanation of the symptom is too mecha- nical, particularly when it is recollected that idiopathic inflammation of the peritoneum will generally (although not always) produce the same effect, and that it is as regular, as constant, HERNIA. 747 and as complete in omental as in intestinal ruptures. At a very early period of the case the stomach becomes engaged, and there is vomiting, at first in large quantity until the contents of the stomach are evacuated ; it is then less, dark-coloured, and excessively bitter; and finally a substance is discharged having the appearance and fetor of the feculent contents of the great intestines. Considering the structure and functions of the valve of the ileum, it ap- pears curious how an anti-peristaltic motion could be so completely established as to permit of actual fcecal vomiting, and the fact (if it is a fact) cannot be explained except by supposing the action of all the constituent structures of the intestine so deranged that the influence of the valve is altogether lost. But it is more than doubtful whether this material is really feculent, although it is difficult from its sensible qualities to consider it in any other point of view; for I have frequently seen this vomiting in cases where the hernia were formed of loops of the lesser intestines, and therefore when the contents of those beyond the iliac valve could not have been thrown off ; and in every case it is difficult from the examination of the dis- charge to determine its nature with accuracy. After the stomach has been emptied of its natural contents, the act of vomiting assumes a very peculiar character : strictly speaking, it is not vomiting or retching, nor is it hiccup, but a slight convulsive effort like a gulp, which brings up without much effort the quantity of a single mouthful at a time. The forehead is now bedewed with a cold and clammy sweat; the countenance presents a remarkable expres- sion of agony and anxiety ; and the pulse is small, quick, hard, and vibrating, as is the case in all internal inflammations of vital parts. After some further time (and the period is very variable) the characters of the disease undergo a fearful alteration. Mortification attacks the incarcerated viscus, and in most instances seems to bring the result of the case to a very speedy issue. The tumour now loses its tense feel, and becomes soft, flabby, and perhaps emphysematous : in some instances it retires altogether. The belly also may become soft, and in general there is a discharge per anum of dark-coloured and abominably offen- sive fseces. This evacuation leads the patient into the encouragement of false hopes, for he may have seen his surgeon endeavouring to procure stools during the progress of the case, and combining this circumstance with the removal of the pain and the comparative ease he so suddenly experiences, he fancies so favour- able a change to be the harbinger of recovery. But the delusion lasts not long. The pulse becomes low, weak, and faltering : often it intermits irregularly. The countenance is sunken, and assumes an appearance that cannot be described, but is known by medical prac- titioners as the " facies Hippocratica." The eye lias a suffused and glassy look, and there is a certain wildness of expression very character- istic. The forehead is bedewed with a cold and clammy sweat ; the extremities become cold; the sensorium is affected with the low muttering delirium, and death soon finishes the picture. These symptoms have been laid down as indicative of mortification having taken place, probably because the protruded viscus has generally been found in that state ; and from habit many practitioners have on their appear- ance in cases of purely idiopathic peritonitis decided on the presence of gangrene, and the hopelessness of recovery. Such cases are hope- less, and patients have died, but not of mortifi- cation, for although these symptoms are present in most cases of fatal peritonitis, yet dissection after death very rarely exhibits gangrene in that disease, and perhaps for this reason, that the functions of the abdominal viscera are too im- portant to life for a patient to struggle suffici- ently lonrj with their inflammation to permit of mortification being established. Whilst the inflammation is very active, and the serous membrane dry, or lymph only secreted on its surface, then is the pain intense, and the first order of symptoms developed : but when effu- sion has taken place, and the vessels are relieved by the pouring forth of serum or sero-purulent fluid, the pain abates, and the symptoms are those of extreme debility. In confirmation of this remark it may be observed that, when a patient dies from any sudden effusion into the peritoneal cavity, whether from a ruptured intestine, or gall-bladder, or bloodvessel, or from any other source, the symptoms from the very commencement are those of debility and collapse — the same sunken and anxious look, the same feeble and fluttering pulse, and the same kind of universal sinking of the entire system. However, although the symptoms may be very formidable, the state of the patient is not altogether hopeless. Art may still accomplish a great deal, and even the operations of nature alone and unassisted may succeed in prolonging life, although under circumstances that render life scarcely desirable. When the hernia has proceeded to gangrene and the patient still lives, the skin of the tumour assumes a very dark red and livid colour, and then becomes black in spots. The cuticle separates and peels off in patches, and some one or other of the sphacelated parts giving way, a profuse dis- charge bursts forth, of a horribly offensive nature. In the same way may the surgeon's interference prove serviceable. It is related by Petit, that travelling once, he met in the out- house of an inn an unfortunate being thrown on a heap of straw in a corner to die. He im- mediately recognized the smell of a gangrened hernia, and proceeded to give the poor fellow all the relief within his power. He made an incision, allowed the feculent matter to escape, cleared away the gangrenous and putrid parts, and having ordered a poultice left him to his fate. On his return he found him able to move about and perform active service within the stable, and even free from the disagreeable accompaniment of an artificial anus at the groin. This is a most gratifying piece of suc- cessful surgery, but it is not one that is very frequently realised. In order to the possibility 748 HERNIA. of an artificial anus being formed, the patient and the hernia must be placed under circum- stances so very peculiar that it will be easily perceived how unlikely it is that they should be united and combined in one individual. 1 . Although the protruded viscus has become sphacelated, the inflammation within the ab- domen must not have reached such a height as to preclude the possibility of recovery. 2. Adhesions must be established between the bowel and the peritoneum either at or im- mediately above the neck of the sac, so that when the stricture is free and the enormous alvine accumulation allowed to escape, it will be impossible for the gut to withdraw itself within the cavity or be removed from the external aperture. And in order that the annoyance of the arti- ficial anus should be subsequently removed, it is necessary that the intestine and the perito- neum to which it is adherent should retire into the abdomen, and that the angle between the two intestinal tubes should be diminished or removed. 1. If the first of these conditions is indispen- sable, it follows that the chance of recovery with artificial anus is inversely as the acuteness of the symptoms and the rapidity of their pro- gress. As it is the inflammation of the intes- tines that destroys the patient, it is pretty evi- dent that after it has reached a given point, no operation performed on the hernia and no evacuation of the contents of the bowels can arrest its progress, or cause the absorption of the lymph, or of the sero-purulent fluid that has been effused into the peritoneal cavity. In operating on the living subject within twenty- three hours after the first appearance of the hernia, I have found the intestine sphacelated : in this case, when the stricture was divided, the discharge from the intestines within the ab- domen was trifling in quantity, and in order to relieve the patient, I was obliged to introduce a gum-elastic tube for a considerable way into the superior fragment of the bowel. He died on the subsequent day, and on examining the body the front of the intestines seemed to be one mass of plastic lymph, which obliterated every appearance of convolution, and must have glued together the bowels in such a manner as to prevent the possibility of a peristaltic motion. In a case so aggravated no hope could be enter- tained from the establishment of an artificial outlet. It can now be easily imagined how persons of a very advanced age,* and in whom the symptoms of strangulation are mild and chronic, recover with artificial anus, in short that such a consummation is most to be ex- pected in the cases to which the name " incar- cerated" has been applied, whereas in most instances of " strangulated" hernia its occurrence is unlikely, and in many altogether impossible. 2. The second great requisite for the esta- blishment of an artificial anus is, that adhesion shall take place between the bowel and the peritoneum, either at or immediately above the * See Louis' Memoir on hernia followed by gan- grene. Mem. de l'Acad. Uoy. v. 8. neck of the sac, so that when the stricture is free and the alvine discharges allowed to escape, it will be impossible for the gut to withdraw itself within the cavity, or be removed from the external aperture. This adhesion has, I think, been generally supposed to occur "during the inflammation which precedes the gangrene,"* but is nevertheless probably always not only subsequent to it, but to the separation of the unsound and sphacelated parts; and the at- tachment is, not between the contiguous and opposing smooth surfaces of the serous mem- brane, but between the divided edges of the sound portions of the tube remaining after the slough has been thrown off, and the part of the neck of the sac adjacent to them. I have ope- rated on a great number of gangrened herniae, and never found such an adhesion to have pre- viously existed, neither have I ever met with it on dissection, and I cannot conceive the possi- bility of a spontaneous return after sphacelus (an event that but too frequently occurs) if the parts were thus attached together. Assuredly if such adhesions were formed at so early a period, they ought to be much more frequently found, and they would be amongst the most calamitous complications that could attend a hernia ; for they would offer an almost invinci- ble obstacle to its reduction, or supposing the bowel to have been pushed up by force, such a sharp angular fold would be formed as must prevent the passage of its contents and create an internal strangulation. Nor is the consider- ation of this fact practically unimportant, if it leads us to adopt every possible precaution that may conduce to the undisturbed progress of this adhesive process, and at the same time warns us not to be too sanguine in our expecta- tions. I have (as I have said) operated on a vast number of cases of gangrened hernia, not one of which recovered with artificial anus: some, the great majority, perished, as has been remarked, in consequence of the inflammation within the abdomen having reached an incurable height ; some others sank exhausted and died, the system being apparently worn out and incapable of a recuperative effort : others still, from a retraction of the divided end of the bowel and the escape of its contents into the cavity; and one, from a cause which, as it has not been mentioned by any pathological writer, may be noticed here. On the spontaneous separation of the sphacelated bowel, a frightful and incon- trollable hemorrhage took place, some of which flowed into the peritoneal cavity, and was found after death diffused through the convolutions of the intestines. When a case has been so fortunate as to permit of the formation of an artificial anus, after the mortified parts and putrid sloughs have been removed a cavity is seen, generally irregular and puckered at its edge, leading down to and communicating with the injured * Scarpa on hernia, p. 323. See also Travers on wounded intestines. " Dans les hernies, ces adhe- rences precedent la destruction des parties, et elles previennent le plus souvent 1'epanchernent des matieres dans le ventre." — Dupuytren, Lecons Oralcs, torn. ii. p. 197. HERNIA, ?40 intestine, from which the fecal discharge is constantly trickling, and as there is often a suffi- cient space for a portion of this to lodge and remain, it may prove a source of troublesome and dangerous ulcerations. In a short time the mucous membrane becomes everted and protrudes, often, if neglected, to the extent of several inches : it is a true prolapsus of the membrane, not very unlike the prolapsus ani in appearance. At the bottom of the cavity al- ready mentioned, are the orifices of the intes- tines, the superior of which is the larger, as it is from it the discharge proceeds, whilst the inferior is small and so contracted as frequently to be discovered with difficulty. The partition between the orifices is formed by the juxta- position and adhesion of the sides of the intes- tine : it is termed the " eperon" by Dupuytren, and is larger and more obvious when a portion of the bowel has been completely removed so as to divide the tube into two parts, smaller when only a knuckle has been pinched up and gangrened without engaging the entire circum- ference. To this " eperon" and double partition the mesentery is attached, and the functions of this membranous ligament are said to exert a very important influence on the progress and after-consequences of artificial anus. Not only is the superior portion of the intes- tine (that which is in relation with the stomach) larger, but its extremity being fixed by the new adhesions, the progress of its contents is greatly facilitated, and according to Dupuytren actually accelerated as to time. The inferior or rectal portion, not performing its functions, becomes diminished in calibre, and contains a white, pulpy, albuminous material, which is sometimes discharged by stool, but may remain undecom- posed within it for months or even years. The contracted condition of this portion of the gut is of the highest importance to be attended to in all instances where a recovery is possible or likely to be attempted. This disposition of all hollow structures in the body to accommodate themselves to the bulk or quantity of their con- tents has been already noticed, and to obviate the inconveniences likely to arise from such diminution, the older surgeons* strongly recom- mended the use of enemata, in order, amongst other advantages, to preserve the intestine in a sufficient state of distension. The progress and termination of a case such as has been under consideration may be ex- tremely variable. The aperture may be situa- ted in the lesser intestine so high up or so near the stomach that the space to be traversed by the aliments and their period of detention are shortened : their digestion is then incomplete and nutrition so far impaired that the patient sinks gradually, and dies from the effects of inanition ; or a permanent artificial anus may be established without a hope or a chance of the natural passage ever being restored ; and this seemed at one time to have been the great object of surgical practice in these cases, for we find M. Littre, a celebrated French surgeon, actually tying up the lower portion of the gut * See Louis' Memoir, loc. citat. when he could find it, as if to preclude for ever a possibility of the continuity of the tube being restored. This is a most deplorable condition, yet have patients endured the annoyance of a permanent discharge at the groin for a great length of time ; and in the Museum of the School in Park Street, there is a preparation taken from a man who had thus existed for upwards of ten years. There is a curious in- stance mentioned by Louis in which something resembling the regular action of a sphincter was clearly observable, and although the discharge of the faeces was involuntary, yet it was periodical, and the gut once evacuated remained closed until a new accumulation took place. This person, of course, was comparatively free from that constant trickling of feces which is the patient's chief annoyance, and which, if not palliated by some ingenious contrivance, abso- lutely renders his life loathsome. The natural passage of the feces has been restored. This is so desirable, so fortunate a consummation, and its practicability so clearly established by the circumstance of its being oc- casionally accomplished solely by the operations of nature, that it can be no matter of surprise if surgeons have laboured to attain it and dili- gently observed the entire process. An intes- tine of which a portion has sloughed away is placed in a very different condition from one that has been simply wounded. When an en- tire loop of bowel has been removed, the two portions within the abdomen passing down to the neck of the sac lie more or less parallel to each other, or approach by a very acute angle : they are in the same degree perpendicular to the ring, and between them is that double parti- tion termed "eperon" or buttress by Dupuy- tren, and the " promontory" by Scarpa. Novv as the intestines are fixed and fastened in this posi- tion, the canal can never again become conti- nuous in directum, and therefore any material that passes from the upper into the lower portion must do so by going round this inter- vening promontory. Even when only a small fold or knuckle has been lost, although the complete continuity of the tube is not destroyed, and the partition is less evident and prominent, still an angle must inevitably be formed of suffi- cient acuteness materially to impede the pro- gress of the feces. In neither case, then, can the wounded edge of one portion of the intes- tine come to be applied to that of the other, nor can adhesion or union by the first intention ever be accomplished between them. In lieu of this, however, the edges of the intestine be- come united with the peritoneum opposed to them, which must of necessity be the neck of the sac, and then if the external wound can be healed, a membranous pouch or bag is inter- posed between them, of a funnel-shape, and which serves as a medium of communication and of conveyance for the fecal matters from one portion of the tube into the other. Reflecting on this pathological condition of parts, it will not be very difficult to explain some of the varieties observed in cases of artificial anus. The chief obstruction to the re-establishment of the canal is the intervention of the promontory. 750 HERNIA. If it is so large or otherwise so circumstanced as entirely to impede communication, and if in this condition it is neglected, the discharge must take place at the groin, and the disease is permanent. Such, I believe, is the history of most of those unhappy beings who have borne about them for years this loathsome and dis- gusting affliction, until relieved by a deatli that could not have proved unwelcome. In a vast number of cases the projection is not so great, and although it may impede and delay, it does not altogether prevent the passage of fasces from one portion of the tube to the other : then as the external wound contracts, the neck of the sac forms into a membranous funnel or canal of communication, and the fseces begin to pass. The wound then heals, in some in- stances leaving a small fistulous opening through which a limpid, straw-coloured, but fetid fluid constantly distils, whilst in others a perfect and complete cicatrix is formed. But we must recollect what happens in this seem- ingly perfect cure before we can fully appreci- ate the entire nature of the case, and the degree of danger that always overhangs it. It is evident that the viscus must (at least at first) be firmly fixed at the situation of the cicatrix ; that it no longer enjoys any freedom of motion, and that it forms an angle more or less acute at the place of adhesion. It is also probable that the diameters of the two portions of intestine do not correspond. Hence the process of diges- tion is impaired, the patient must study every article of food he consumes, and the slightest indiscretion is followed by colicky pains, flatu- lence, and tormina of the bowels ; often there is nausea, vomiting, loss of appetite, and a drag- ging sensation at the stomach, this latter symp- tom being explained by the omentum having formed a part of the protrusion, and become ad- herent at the new-formed cicatrix. It often happens that the scar gives way, and a facal discharge takes place again, the groin thus alternately healing up and bursting out anew. This is more likely to occur in cases where the very small fistulous canal has remained, and therefore many surgeons have regarded this event as more fortunate than where the cica- trization has been complete ; for the course of the fistula serves as a guide to direct the burst- ing of the accumulation externally, whereas if, as sometimes happens, the intestine should give way internally, its contents are then poured out into the peritoneal cavity, and the result must be inevitably fatal. The most curious circumstance connected with the healing of an artificial anus is, that the position of the united intestines and the intervening infundibulum or funnel behind the cicatrix is not permanent. " It is," says Scarpa,* " a certain fact confirmed by a very great num- ber of observations, that after the separation of the gangrene the two sound segments of intes- tine retire gradually beyond the ring towards the cavity of the abdomen, notwithstanding the adhesion which they have contracted with the neck of the sac, whether this is caused by the tonic and retractile action of the intestine itself and of the mesentery, or rather by the puckering of the cellular substance, which unites the hernial sac to the abdominal parietes within the ring. And this phenomenon is likewise constant and evident even in herniae not gangrenous, but merely complicated with fleshy adhesions to the neck of the sac, and therefore irreducible. In these hernia;, the immediate cause of stran- gulation being removed, the intestine, together with the hernial sac, gradually rises up towards the ring, and at last is concealed behind it." The same fact has been observed by Dupuy- tren,* who attributed it to the continued action of the mesentery on the intestine. Many indi-. viduals who had been cured of artificial anus without operation returned to the Hotel Dieu at very remote periods, and died of diseases having no relation to the original complaint. The parts were curiously and carefully examined, and the intestine, instead of being fixed to the walls of the belly, was found free and floating within the cavity. There could be no doubt of the identity of the individuals, and moreover a fibrous cord was seen extended from the point of the wall of the abdomen which corresponded with the former artificial anus, to the intestine. This cord, some lines in diameter and some inches in length, thicker at its extremities than in the middle, covered by peritoneum, and formed entirely by a cellular and fibrous tissue without any cavity, was evidently produced by the progressive elongation of the cellular membrane that had united the intestine to the wall of the abdomen ; and the cause which had occasioned this elongation was nothing else than the traction exercised by the mesentery on the intestine in the different motions of the body during life. Having now endeavoured to describe gene- rally the circumstances or conditions under which protrusions of the abdominal viscera may exist, I proceed to consider the peculiarities that arise from situation, premising that it is not my intention to enter very minutely into the descriptive anatomy of those several situa- tions in their normal or healthy states, but only in reference to and in connexion with the ex- istence of the disease under consideration. Inguinal hernia. — When a viscus is pro- truded through one or both of the apertures termed rings, situated at the anterior and infe- rior part of the abdomen, near the fold of the groin, but above Poupart's ligament, the hernia is termed inguinal. It may exist, therefore, in three different conditions. 1. Where the in- testine has been pushed through the internal ring only, and is lodged in the inguinal canal : it then appears as a small, round, firm, and moderately elastic tumour. 2. Where it has passed through the internal ring, through the inguinal canal, through the external ring, and dropping down into the scrotum of the male or the labium pudendi of the female, appears as a larger and more yielding tumour, of a pyrami- dal shape, the apex of the pyramid being di- rected towards the anterior superior spinous * Scarpa, op. citat. p. 313. * Le9ons Orales, torn. ii. p. 207. HERNIA. 751 process of the ilium. As these are but different stages of the same disease, both come under the appellation of hernia by the oblique descent. But, 3, when the viscus has been forced through the parietes immediately behind the external ring, and passes out through that natural aperture only, it is then for obvious reasons termed the hernia by direct descent; and although the external characters of the tumour are not always such as to point out the peculiar nature of this protrusion, yet the relative posi- tion of the intestine with respect to adjacent parts must be somewhat different in these seve- ral cases, a difference that will be found to be of some practical importance. The peritoneal sac, as viewed internally in the direction of the iliac and inguinal regions, is described by Scarpa as being divided into two great depressions at each side, the medium of partition being the ligament into which the umbilical artery of the foetus had degenerated, together with the fold of peritoneum raised by that ligament. Of these fossa? the superior or external is the larger and deeper; it is that within which the intestines are collected when strongly compressed by the abdominal muscles and by the diaphragm in any violent exertion ; and from it inguinal hernia is most frequently protruded, as the ligament and duplicature of the peritoneum prevent the compressed viscera lodged in this fossa from removing out of it to descend into the pelvis. The situation of the umbilical artery varies considerably : some- times it is close upon the internal border of the internal ring, in other subjects at the distance of half an inch from it, or even more ; but it is always at the pubic side of the epigastric ves- sels. Thus, in its direction upwards and in- wards towards the umbilicus it crosses ob- liquely behind the inguinal canal : all hernia?, therefore, by the oblique descent pass out from the external or superior abdominal fossa, while those by the direct are in relation to and are protruded from the inferior or internal. Inde- pendent of this configuration there is nothing in the peritoneal cavity as viewed from within, to determine the occurrence of hernia at one place rather than at another. The membrane is in all parts equally smooth and polished, equally strong,* tense, and resisting. This, however, is not the case with respect to the muscular and tendinous walls of the abdomen, which vary very considerably in density and strength in different situations, and in these qualities dissection shews that the hypogastric or inguinal regions are the most deficient and therefore most disposed to permit of the occur- rence of hernia. In prosecuting the dissection from within (which is by far the most satisfactory manner), the peritoneum may be detached by the fingers or by the handle of the knife in consequence of the laxity of the cellular tissue connecting it to * The strength of the peritoneum is proved by a curious experiment of Scarpa's. He stretched a large circle of this membrane recently taken from the dead body, on a hoop like a drum, and found it capable of supporting a weight of fifteen pounds without being ruptured. the adjacent external structures. The fascia transversalis then comes into view, and in it the aperture termed the internal ring, through which the spermatic cord in the male, and the round ligament in the female are transmitted. This aponeurosis varies in density and thick- ness in different individuals : it is continuous with the fascia iliaca, and is connected with the posterior edge of Poupart's ligament : it is denser and stronger externally, and becomes weaker and more cellular as it approaches the mesial line. Where the internal oblique is muscular, the connexion between it and the fascia transversalis is extremely lax, cellular, and easily separable ; but after it becomes tendi- nous, the union is much more intimate, and the fibres of the one can scarcely be distinguished from those of the other unless by the difference of their direction. In most subjects the internal ring is very indistinct, its size, shape, and direc- tion being in general determined rather by the knife of the anatomist than by nature. So far as the fascia is concerned, the external inferior border of the ring is its strongest part, but its internal edge seems to be the stronger as it is supported by the epigastric vessels, and some- times by the remnant of the umbilical artery. Its size is about an inch in length, half an inch in breadth ; its shape oval ; and the direction of its longest diameter perpendicular or slightly inclining from above downwards and outwards. The position of the epigastric artery with re- spect to the neck of the sac at once points out whether a hernia is by the direct descent or not, for it marks the internal or pubic boundary of the internal ring. This vessel is occasionally irregular in its origin, but in its normal or usual state it comes off from the external iliac before it has reached Poupart's ligament, and conse- quently in that position it lies behind the bag of the peritoneum, which it passes by forming an arch, the concavity of which is directed up- wards. It then appears in front, between the fascia transversalis and the peritoneum, but more closely attached to the former, with which it remains when the membrane is torn away. The vas deferens is seen coming from the pel- vis obliquely upwards and outwards until it reaches the spermatic artery, which, having de- scended from above, nearly in a perpendicular direction, meets the vas deferens at rather an acute angle, the former being to the outside and nearly in front of the latter. These vessels having passed the fascia transversalis disappear by arching round the epigastric artery and en- tering the inguinal canal, and they define the inferior margin of the internal ring. The re- mainder of its border is not so very distinctly marked, partly in consequence of a very deli- cate fascia which is given off from it and passes down a short way on the spermatic cord, where it becomes indistinct and is lost; and partly because the transversalis muscle lying before it renders the view obscure. The internal border of the internal ring is always (as stated by Sir A. Cooper) midway between the anterior superior spinous process of the ilium and the symphysis pubis. When a protruded viscus, then, is passing 752 HERNIA. through this ring, it lias the epigastric artery to its internal or pubic side, and generally the vessels of the cord behind it ; but a variety sometimes occurs, for the hernia may protrude exactly at the spot where the spermatic artery and vas deferens meet each other at an angle, and separate these vessels from each other, leaving the artery rather to the outside and in front, the vas deferens still occupying its usual situation behind. After the hernia has passed the fascia transversalis, it is still behind the fibres of the internal oblique and transversalis muscles, and has to pass a few lines (the dis- tance varying in different subjects) before it reaches the posterior surface of the tendon of the external oblique. On prosecuting this dis- section further by detaching the fascia trans- versalis from the transversalis muscle in a di- rection downwards and outwards, the intestine will be found to have entered a canal of an inch and a quarter to an inch and a half in length, its direction being obliquely downwards and inwards to the external ring. This is termed the inguinal canal, and is thus formed. Pou- part's ligament, whether it be considered as a portion of the tendon of the external oblique or not, is powerfully strong and thick : to it the fascia transversalis is firmly adherent behind, and the thinner and more expanded fibres of the tendon of the external oblique before. Between these, then, a sheath is formed in which the hernia is lodged, having in front the tendon of the external oblique, and also covered by the cremaster muscle, particularly that part of it which has its origin from Poupart's liga- ment. Behind it is the fascia transversalis, and more internally or nearer the pubis the conjoined tendon of the internal oblique and transversalis, and below is Poupart's ligament. Above, it is crossed obliquely by the inferior margin of the internal oblique and transversalis. These muscles have a fleshy origin from the ex- ternal third of Poupart's ligament, from which they pass in an arched form to be inserted by a common tendon into the crest of the pubis. Under this arch the viscus slips and thus places itself anterior to the conjoined tendon before passing through the external ring and becoming a scrotal hernia. Anatomists have not agreed in their descrip- tions of the internal oblique muscle, although a correct and accurate knowledge of the situa- tion of it and of the transversalis in the neigh- bourhood of the rings is indispensable to the right understanding of hernia. According to Sir A. Cooper* and Lawrence,f the upper part only of the internal ring is shut up by these muscles, leaving the lower unprotected, and con- sequently, according to this view of the subject, a hernia on entering the inguinal canal should have them above it. CloquetJ states that the inferior border of the transversalis passes on a level with the superior, opening internally, but the edge of the internal oblique is lower down, * Page 6. t Lawrence on Ruptures, p. 162. $ Anatomy of Hernia, by Jules Cloquct, trans- lated by M'Whinnie, p. 6. covers the spermatic cord in the inguinal canal, and passes over it to be inserted into the pubis at the point where it escapes from the inferior opening of the canal, that is, the external ring. Scarpa* gives a different description still, where he says, " towards the side at about eight lines distance from the apex of the ring, the lower muscular fibres of the internal oblique muscle separate from each other to allow the sper- matic cord to pass between them ;" and Guthrief considers the occasional passage of a hernia through the fibres of this muscle, and its compression by them, to be no unfrequeut cause of strangulation. It is not easy to reconcile these conflicting authorities, which in them- selves demonstrate the fact that the inferior- border of this muscle exhibits some varieties in its relation to the inguinal canal and internal ring according to the extent of its origin from Poupart's ligament. When a hernia is present, I have always seen it arched over the neck of the sac, and although I would by no means assert that a rupture never takes its course between these muscular fibres, yet I have not met with an instance, and as I have observed elsewhere, I imagine such an occurrence would create a deviation from the usual relative anatomy of the cremaster muscle with respect to the hernial sac— See Abdomen. The inguinal canal terminates in front at the external ring, which is formed by a separation of the fibres of the external oblique muscle as it passes inwards and downwards to be inserted into the pubis. Almost immediately after the muscle has become tendinous, a disposition to this separation is observable, and a kind of split is formed in the tendon, the edges of which are, however, pretty firmly held in their re- lative positions by fibres passing closely and irregularly across from one to the other. These fibres have been called the intercolumnar fascia. Besides these there is a very remarkable ar- rangement of tendinous fibres seeming to arise from Poupart's ligament, and thence radiating in an arched form (the convexity of the arch looking towards the pubis) to form a strong in- terlacement with the fibres of the external oblique.;]; Independent of these adventitious bands the tendon itself, as it approaches the crural arch and the pubis, seems to become thicker and stronger ; and (as has been remarked by Scarpa) in the dead body after the integuments are removed and the parts left for some time exposed, the lower portion of the aponeurosis appears opaque and dense, while the part above the umbilicus preserves its transparency, and allows the fleshy fibres of the subjacent muscle to be seen through it. The separation above alluded to being effected, the tendon is divided into two portions, termed the pillars of the ring : the anterior or internal is broader and flatter, and runs to be inserted into the pubis of the opposite side, and the ligamentous sub- stance that covers the front of this bone. The » Page 25. t Anatomy of Hernia. | Sometimes termed Camper's fascia, from its being so admirably delineated in the " Icones." HERNIA. 753 mferior or external is rounder and more firm, and attached to the external part of the crest or tuberosity of the pubis. A triangular aperture is thus formed of about an inch or an inch and a quarter in length, the base of which, nearly half an inch across, is situated at the pubis, from which it tapers gradually off in a direction upwards and outwards. For a neat demonstra- tion of this aperture we must also be largely indebted to the knife of the anatomist, its edges being obscured by a fascia* which comes off from them, and passing down on the cord is generally of sufficient density to admit of being traced as far as the tunica vaginalis testis. This ring is never well developed in the female, it then being smaller, rather of an oval figure, and from its deficiency of size appearing to be nearer the pubis than in the male : even in subjects of the latter sex the size of this open- ing exhibits considerable variety. When a hernia has descended through it, the shape and direction of the external ring are altered : the inferior pillar is still more flattened and runs in a more horizontal direction ; the superior is banded in an arched form rather tightly above it ; the shape of the entire ring is rendered more oval and its direction more horizontal ; but still its relative position with respect to the bone is so far preserved that no hernia can pass, with- out its internal edge resting on this bone. In dissecting a hernia of this description from without, after removing the skin and cellular tissue more or less loaded with fat, the fascia superficialis is exposed. This is a tegu- ment investing most parts of the body, though far more dense iu some situations than in others, and is situated beneath the subcuta- neous fat, with which it is sometimes so much identified as to render its demonstration diffi- cult. At the groin it is usually well developed, and is described as consisting of two distinct lamina, but may {by such as are curious in these dissections) by care be separated into many more.f The superficial layer is very lax, passes over and has no connexion with Poupart's ligament, and is very generally re- moved along with the skin and fat by the in- experienced dissector. Its removal exposes some of the glands of the groin. The deep iayer is more membranous, and possesses more of the determined character of a fascia. It adheres intimately to the muscular fibres of the external oblique, passes thence inwards over the tendoB, to which it cannot be said to be attached, as the connecting cellular tissue is extremely loose, and meets its fellow of the opposite side at the linea alba, to which both are attached. It has an insertion into the pubis, and its adhesion to Poupart's ligament is in many respects extremely intimate. Pass- * This also has been called an intercolumnar fascia, and a spout-like fascia, &c. It is to be re- gretted that such a confusion of nomenclature ob- tains in the description of these parts, — a confusion always embarrassing to the student, and rendering the subject uselessly perplexing and difficult. t Velpeau describes three distinct layers. Ana- tomie des fiegions, torn. ii. p. 70. VOI,. II. ing down in front of the thigh, it covers* several of the lymphatic glands, or in many instances leaves small apertures or deficiencies in which glands are lodged : it then reaches the opening in the fascia lata for the transmission of the saphena vein, to the edge of which it adheres more or less closely, and afterwards descends upon the thigh, having this vein interposed between it and the fascia lata. At the external abdominal ring the fascia superficialis sends down a sheath-like process, investing the cord and descending down over the tunica vaginalis and the testicle : it must, therefore, under any circumstances give a covering to the hernial sac. On the removal of this, the fascia that comes from the edges of the pillars of the ring is observed, and this is generally much thicker and firmer than in the normal condition of the parts. When so thickened, it also admits of subdivision into several laminae. Immediately underneath is the cremaster muscle, its fibres spread out and separated so as to resemble a fascia, though in some instances the contrary may be observed, and they are seen gathered into bundles and greatly thickened. Still deeper are three other layers of fascia, perhaps derived from that which comes from the edges of the internal ring, and finally the hernial sac is exposed. In herniae of moderate size, the spermatic artery, veins, and the vas deferens are usually found in one cord and enclosed in one common sheath lying behind the sac : some exceptions, however, to this rule are observed, one of which, wherein the bloodvessels are situated on its anterior and external surface, and the vas defe- rens posteriorly and internally, has been already noticed and explained. But there is another deviation that seems to be occasioned by the growth of the hernia, and the compression exer- cised by it on the cellular substance connecting the constituent parts of the cord together. It can therefore only be met with in large and old ruptures. Thus, as the tumour increases, it causes this cellular tissue to be stretched just as if the vas deferens and the artery were pulled asunder in different directions, whilst the sac insinuates itself between them, until finally the vessels come to lie on one side of the hernia, or it may be to occupy its anterior surface. The greatest divarication of these vessels exists, as might a priori be expected, towards the lower part of the tumour; it is less towards the middle, and scarcely if at all above, and in the vicinity of the neck of the sac. A knowledge of this fact may teach us to beware how we prolong an incision very far down in operating on large and old hernise. Perhaps the next point of practical import- ance to consider is, whether, with all this ana- tomical and pathological information, it might nevertheless be possible to mistake this disease and confound it with any other affection. The * The inguinal glands arc generally described as lying between the layers of the superficial fascia. On dissection, this has not appeared to me to be the case, 3 D 751 HERNIA; hernia just described may exist in two different conditions ; one, in winch it is still lodged within the inguinal canal, and appears in the form of a tumour in the upper part of the groin, termed bubonocele ; the other, in which it has escaped through the external ring, and having dropped down constitutes scrotal hernia. When the rupture has descended no farther than the groin, there are but two affections that can bear any resemblance to it : these are, the testis itself whilst in the act of descending, if this process has been delayed beyond the usual period of life, and an enlarged inguinal gland. However possible in cases of crural hernia (as shall be noticed hereafter), a mistake of the latter description is not likely to occur in the disease under consideration, but there is an ob- servation of Mr. Colles on this subject de- serving of attention. "I do not suppose," says this distinguished professor, " that any surgeon of competent anatomical knowledge could mistake it for inflammation of those lymphatic glands which l,e in the fold of the groin, but an enlargement, whether from a venereal or any other cause, of two lymphatic glands which he on the side of the abdomen, as high up but rather more internally than the in- ternal abdominal ring; an enlargement of these glands will produce appearances resembling those of inguinal hernia."*' It seems almost surprising how the descent of the testicle could possibly be mistaken for a hernia when the mere examination of the scrotum would throw such an explanatory light upon the subject, but a consideration of the following circumstances will be useful in solving the difficulty. 1st, The detention of the tes- ticle within the abdomen until an unusually late period is by no means so infrequent an oc- currence as is generally supposed even by sur- geons in considerable practice : I have heard a military medical officer observe on the great number of young men that had passed before him for inspection after enlistment, in whom one and sometimes both the testes had not de- scended. 2d, The symptoms of both affections bear a general though not necessarily a close resemblance ; for the situation of the tumour is exactly the same, and if the testicle is com- pressed and inflamed, the pain and tenderness and the inflammatory fever are to a certain ex- tent like the symptoms of strangulation. But I have not met the same costiveness, at least the same obstinate resistance of the bowels to the operation of aperient medicines, nor the same vomiting, nor the same exquisite tender- ness spreading over the abdomen, and the pulse is not that small, thready, hard, and rapid vi- bration that is produced by peritoneal inflam- mation. In one case I perceived that pressure on the tumour occasioned that sickening pain and sensation of faintness which a slight injury of the testicle so often produces; and I imagine that in this case a light and very gentle per- cussion might prove a useful auxiliary dia- gnostic. But, 3rd, it does not always happen * Colles's Surgical Anatomy, p. 46. that the surgeon takes sufficient pains to inves- tigate the disease before him. " He is apt," says Mr. Colles,* " at once to set down the case as incarcerated hernia, a complaint with which he is familiar, and does not suspect the exist- ence of a disease which is to him perhaps ex- tremely rare. Boys sometimes indulge in the trick of forcing up the testicles into the ab- domen, which may be followed by unhappy consequences, for the gland may not descend again, or if it does, perhaps a portion of in- testine slips down along with and behind it, which may then become strangulated, while its presence is unsuspected and the symptoms attributed to compression of the testis." A boy, about seven years of age, had forced the left testicle into the abdomen : ten years afterwards, the inguinal ring having probably become un- usually contracted, the testicle passed under the femoral arch with all the symptoms of stran- gulated hernia, on account of which he was obliged to undergo the operation. | When the hernia has become scrotal, it then comes more to resemble diseases of the testis and of the cord, but in general these are very easily distinguished, and there are only three that could lead a practitioner into error, and then only through unpardonable carelessness ; the hydrocele of the tunica vaginalis testis, the hydrocele of the spermatic cord, and the varicocele or a varicose condition of the veins of the cord. There is not much likelihood that hydrocele of the tunica vaginalis could, in its earlier stages, be mistaken for hernia : it commences below and increases in an upward direction, while a hernia proceeds from above downwards; and at first in cases of hydrocele, the ring, the cord, and all these parts can be accurately felt. As the disease proceeds and the water reaches the ring, a diagnosis is not so easy; still in almost every case of rupture the testis and the cord, particularly the former, can be easily felt lying behind and at the bottom of the tumour, which is not the case in hydrocele. Besides, hydrocele is lighter as to weight ; it gives a sensation of fluctuation to the touch ; it never exhibits that soft doughy character that belongs to omental hernia : moreover it is diaphanous, and the light of a candle can be seen through it, if the tumour is examined in a darkened room. A collection of water within the sheath of the cord must, I should think, be rather an infrequent occurrence ; at least it has not fallen to my lot to meet with many examples of it. Still the practitioner must be aware of the possibility of the disease, and that both from the nature of the accident that occasions it, and many of the accompanying symptoms, it may very readily be mistaken for hernia. A young man fell with his groin against the edge of a tub, and in an incredibly short space of time afterwards a colourless elastic tumour appeared in the usual situation of hernia. * Colles, op. citat. t Scarpa, op. citat. p. 235. HERNIA. 7.55 lie was admitted into the Meath Hospital under the care of the late Mr. Hewson, and though some years have now elapsed I can well recollect the variety of opinions pronounced upon it. It could be partially pushed up, but re-appeared instantly on the pressure being re- moved : it was slightly influenced by coughing, and it was extremely tender to the touch. As the patient was not confined in the bowels, and in fact there was no urgency of symptom, no active treatment was adopted, and the tumour gradually disappeared. It had probably been an effusion of fluid into the sheath of the cord. The manner in which these diseases are said to be capable of discrimination is as follows. Let the tumour be pushed up if possible, and the finger of the operator still be pressed against the ring: if it is a hernia, such pressure will be sufficient to prevent a re-descent ; but if it is only a fluid, it will insinuate itself by the side of the finger and the tumour shortly re-appear. Scarpa* denies the sufficiency of this test in cases of omental hernia of small size, when situated so high up as to occupy and dilate the inguinal ring, and asserts that he had repeatedly observed omental inguinal hernia of a cylin- drical form, which, when scarcely returned, re- appeared again as before without the patient having changed his posture or made the slight- est exertion ; and in like manner hydroceles of the spermatic cord, which, when pushed beyond the ring, remained there as long as the patient kept himself in the supine posture without making an exertion. He seems to rely more on the difference of consistence and regularity of surface in the two tumours, and on the cir- cumstance of the hydrocele being always broader inferiorly, contrary to what is observed in omental hernia. A varicose enlargement of the spermatic vein is not easily confounded with hernia, unless it has increased to such a size as nearly to occupy that side of the scrotum : it is longer in pro- portion to the diameter of the tumour than hernia usually is, and its surface is hard, knotty, and uneven.f These circumstances, however, are not sufficient to remove all obscurity, and a farther investigation must be made by placing the patient in the horizontal position and endea- vouring to empty the vessel ; then let him stand up whilst firm and accurate pressure is maintained upon the ring. If it is a hernia, the tumour will not re-appear; but if varicocele, it will return as speedily or perhaps more so than if no pressure had been made. Mr. CollesJ mentions that a varicose state of the cord may be combined with hernia, throwing great obscurity on the nature of the disease, and for obvious reasons increasing the diffi- culty of its management. Inguinal hernia by direct descent. — I now * Op. citat. p. 98. t These symptoms are not certainly cliaracte" rislic of varicocele. There is a preparation in the Museum of Park Street taken from a man who exhibited them all during life. His disease was an enlarged, knotted, and contorted condition of the vessels of the cord, \ Op. citat. proceed to offer a few remarks on the other form of inguinal hernia, — that by direct descent,* which occurs when, instead of passing through the canal, the protruded viscus is pushed out immediately behind the situation of the ex- ternal ring, through which it passes directly. The inferior part of the inguinal canal is the weakest of all the parietes of the abdomen. Externally, independent of the external oblique muscle, it is protected as far as the external third or half of Poupart's ligament by the fleshy fibres of the internal oblique and trans* versalis muscles, and by the fascia transversal is, which is dense and strong in this situation, but becomes gradually weaker internally, and is nearly lost before it reaches the mesial line. More internally it is supported by the conjoined tendon of these muscles, but as it arches over the spermatic cord that portion of the peri- toneal cavity which corresponds with the inferior and posterior part of the inguinal canal must depend on the fascia transvers.alis alone, now becoming weaker and less capable of resist- ance. More internally still, and immediately behind the external ring, this region is best supported, and there are many natural obstacles to the production of hernia in this situation. Besides the fasciae already mentioned as tending to prevent the separation of one pillar of the ring from the other, and thereby offer an ob- stacle to the passage of any viscus through it, there is anotherf of a triangular shape arising by a pretty broad base from the crest of the pubis, and inserted into the lineaalba for about an inch or an inch and a quarter. It lies behind the tendon of the external oblique, and before that of the internal oblique and trans- versalis, which latter it strengthens materially, and its external edge contributes to close up a part of the external ring. The edge of the rectus muscle extends itself laterally sufficiently far to occupy one-half or one-third of the space behind the external ring, and moreover here the conjoined tendon is particularly strong. Not- withstanding these supports, this part is weak ; and yet when a hernia occurs here, it is not in consequence of yielding or stretching, but be- cause the conjoined tendon actually undergoes laceration. The causes of this hernia are said to be three- fold :J an unnatural weakness of the conjoined tendon ; its absence altogether in consequence of malformation ; and its being ruptured by direct violence. Of these, the second is not likely to occur, and an example of it had not been met with by Sir A. Cooper at the time of the publication of his work : the other two in effect amount nearly to the same thing, or at least stand towards each other in the relation of a predisposing to an immediately exciting cause. * The internal inguinal hernia of Hasselbach, Jules Cloquet, and Velpeau : hernia on the inner side of the epigastric artery of Sir A. Cooper, and a combination of ventral and inguinal hernia ac- cording to Scarpa. f This is frequently termed Colles's fascia, having been first accurately described by that writer, \ Cooper, p. 51. 3 D 2 756 HERNIA. The hernia by direct descent is distinguished from the oblique, 1st, by the appearance of the groin, the apex of the tumour being at the situation of the external ring, and there being no enlargement whatever in the direction of the inguinal canal : this diagnostic, however, has been found fallacious, for in old oblique hernia the internal ring is dragged down and made to approach the external so as to appear to form one continuous opening. Nor is it easy to point out the difference even in dissection ex- cept by the position of the epigastric artery, which in case of oblique descent always lies to the pubic side of the neck of the sac. The neck in some of these cases appears to be arched over and strongly constricted by the superior portion of the ruptured conjoined tendon, which in these cases is more than usually developed, and (as it were) in a state of hypertrophy. It was probably this appearance that led to a belief that strangulation was occa- sionally produced by the action of these mus- cles. 2nd, By the relative position of the tumour with respect to the different structures composing the cord. The cremaster muscle in any hernia cannot be felt, but it occupies nearly its usual position in this, being spread out like a fascia in front of it, but rather towards its outside. The spermatic cord properly so called passes on its external rather than on its pos- terior side; and although all its constituent vessels may be separated in this as in any other species of large and old hernia?, yet generally there is less divarication in this, and the parts lie together more compactly. 3rd, " This tumour differs from the common bubonocele in being situated nearer the penis."* This is cer- tainly true when it is only bubonocele; but when it has descended into the scrotum, the same difficulty that has been noticed as apper- taining to old ruptures must also obtain here. In applying this diagnostic the student must recollect that the internal edges of both hernia? are equally near to the pubis ; it is by looking to the external border of the neck of the tumour that he can render the test available. Scarpa f states that this hernia is returned without being attended by the gurgling sound : this, however, is an observation perfectly new to me, and which I can by no means verify. Lastly, these herniae appear more suddenly and attain a larger size more rapidly : frequently they appear as scrotal ruptures almost from the earliest period. This, however, is still an uncertain criterion, and in- deed with the assistance of all these circum- stances it is always so difficult and frequently so utterly impossible to establish a diagnosis, that no operation should be undertaken under the conviction of the disease being certainly of one form or of the other. This rupture should present to the anatomist the same number of layers of fascia as that by the oblique descent, the fascia transversalis sup- plying the place of that given off from the edges of the internal ring; J but the young surgeon * Cooper. t Scarpa, op. citat. p. 84. J The internal spoul-like fascia. should be cautioned not to expect the same facilities of demonstration in the living subject that he possesses in the dead. In the former, the operator often meets with layer after layer of fascia, numerous beyond his expectation, and to which he can give no name; and it is no un- common circumstance for him to operate on and return a rupture without being able to say of what nature it was — nay, even as to its being inguinal or crural. Crural or femoral hernia takes place at the superior and internal part of the thigh, below the fold of the groin ; the intestine pass- ing out of the abdomen behind Pou part's liga- ment, between it and the transverse ramus of the pubis, through an aperture that has been termed the crural or femoral ring. A know- ledge of the constitution, size, and boundaries of this ring must be of the last importance to the practical surgeon, and accordingly no part of the body has been examined with more minute attention ; yet if by these labours ana- tomy has gained in accuracy of information and very diffuse description, still the student is not much the better for it, inasmuch as almost every anatomist has adopted views peculiar to himself, and thus in the details a degree of con- fusion has been produced that is extremely em- barrassing to the beginner. I shall, therefore, avail myself as little as possible of authorities, and endeavour to describe these parts as they appear upon dissection, commencing from within, which is perhaps the best mode of studying the anatomy of every species of hernia. The distance between the anterior superior spinous process of the ileum and the angle of the crest of the pubis is in the well-formed female about five and a half inches in length, along which space Poupart's ligament is stretched like a bow-string from point to point. The distance from the ligament thus extended, backwards to the edges of the ileum and pubis forming the border of the pelvis, varies accord- ing to the elevations and depressions of these bones; but the entire forms a very considerable space, which is, however, in general so well filled up that unless under peculiar circum- stances this region affords sufficient support and protection to the viscera of the abdomen. On examining the corresponding peritoneal sur- face within, the membrane is found capable of being detruded only at one spot, internal to the view, and about an inch and a half distant from the symphysis pubis. Here, there is a natural aperture varying in size in different subjects, into which the finger may be pushed by a little violence, and a small artificial hernial sac like a thimble be thus produced. On tearing off the peritoneum it is easy to observe the dif- ferent arrangements that serve to support and strengthen this region of the abdomen. From Poupart's ligament three distinct layers of fascia pass off in different directions. The fascia transversalis has been already described as passing upwards on the front of the abdomen, where it is gradually lost. From the inferior and posterior part of the arch another fascia passes, at first downwards, then upwards and HERNIA. 757 backwards, to expand itself over the iliacus internus and psoas muscles ; and it is therefore called the fascia iliaca. These fasciae are per- fectly continuous as far inwards as the external border of the artery, and form a smooth and strong membranous wall for the abdomen in this situation, rather attached to Poupart's liga- ment than coming off or derived from it.* These fasciae separate at this spot and unite again between the artery and vein, thus forming a sheath for the former vessel : in like manner a separate sheath is formed for the vein, when they again separate and leave a small opening, which is the crural ring, but unite before they reach Gimbernat's ligament, to the abdominal surface of which they give an investment, but here the fibrous structure is very weak and differs little in appearance from cellular mem- brane. These fasciae then form a fiat, broad funnel, which has three apertures at top, and the membranous septa are of the greatest use in binding the anterior and posterior faces of this fuunel together : hence a hernia cannot escape through in company with the artery nor with the vein, and hence also the vein is not com- pressed nor its circulation interfered with, even although a. hernia close to it is in a state of strangulation. This funnel descends on the vessels, to which it becomes firmly attached, at about an inch and a half below Poupart's liga- ment, and, according to some anatomists, is there reflected up again on the vessels forming a cul-de-sac or bag. I thus consider the crural ring properly so called to be an aperture formed by a deficiency in the fascia iliaca and transversalis, just as the internal inguinal ring is formed in the latter membrane alone. It is occupied by a loose cellular tissue, and in general by a small absorbent gland. This ring is of a different size in different individuals ; and where it is large, the person may be said to have an hereditary or congenital disposition to the disease ; but a liability to it may arise from accidental circumstances also. It is obvious that in proportion as the space beneath the crural arch is well filled, and the muscles tense and plump, the aperture at the ring must be small ; also that it will be larger according to the greater breadth between the spinous process and the pubis, or as the space under the crural arch is deep. Hence it may be explained why this kind of rupture is fre- quent amongst women who have borne many children, with whom the parietes of the abdo- men are relaxed ; less frequent amongst young and healthy unmarried females, and scarcely known amongst men, the pelvis of the male being narrower, and his muscle better developed by use and exercise. The crural arch or Poupart's ligament is * Their importance in strengthening this part of the abdomen is proved by an experiment of Mr. Colles. " Make in the aponeurosis which covers the iliac muscle an opening capable of admitting the finger. Pass it between the aponeurosis and surface of the muscle, and you will be enabled, with- out much difficulty, to push the finger under Pou- part's ligament down to the fore part of the thigh." Colles, op. citat. p. 68. nothing more than the inferior pillar of the externa! inguinal ring, and is (as has been before stated) inserted into the crest of the pubis ; but it has another attachment to this bone, which, being in intimate relation with femoral hernia, I have delayed the description of until now. As the ligament approaches the pubis, its inferior edge becomes twisted upwards and backwards towards the linea ileo-pectinea, into which it is inserted for a length of from a half to three quarters of an inch. Its shape is triangular, its posterior attachment being somewhat shorter than its anterior ; and its base, which has its aspect towards the vein, is somewhat lunated. In the male its situation corresponds nearly with the external inguinal ring ; and the sper- matic cord rests on it just as it is about to pass from the inguinal canal. The fibrous funnel-like sheath already des- cribed is itself lodged within a cavity which may be called the crural canal, and is thus formed. The fascia lata of the thigh in front has two origins, one from the whole length of Poupart's ligament, the other from so much of the linea ileo-pectinea as gives origin to the pectinalis muscle, and from the ligament of the pubis. This latter portion having passed down the thigh unites with the former below the en- trance of the saphena into the femoral vein, below which point they form one continuous sheath for the muscles of the limb. The por- tion, however, which comes from Poupart's ligament requires more attention. At first it lies completely in front of the upper part of the thigh, and of course leaves a triangular space between it and the other portion, in which are lodged the funnel-shaped fascial sheath, with its contents, the artery and vein, lymphatic vessels, and some glands. About half an inch, or in some subjects a little more, below Pou- part's ligament the internal portion of this fascia appears to be wanting, leaving the vessels un- covered by it as far down as the point of union of the two fasciae : I say appears to be wanting, because the fascia lata is really continued over this space, joins the pubic portion internally, and sends a process upwards to be inserted into the linea ileo-pectinea, external to the lunated edge of Gimbernat's ligament, and be- tween it and the edge of the femoral ring ; but it is here so thin and cellulated that it is generally removed in the dissection. When thus disposed of, the firm portion of the external fascia lata, as it passes to join the internal, assumes a lunated form above and below, and thus the entire apparent deficiency is made to appear of an oval figure, the edges of which are crescentic, and which have been called by the different names of Iley's ligament, Burns' liga- ment, and the crescentic edge of the fascia lata. A finger pushed from above through the crural ring will easily feel the superior margin of this aperture, and its influence on hernia in this situation will soon be made apparent. The femoral or crural canal then is from one-half to three-fourths of an inch in length, and is formed by the fascia lata : it is bounded above, anteriorly by Poupart's ligament and posteriorly by the linea ileo-pectinea; below, anteriorly by the crescentic 763 HERNIA. edge of the fascia lata or I ley's ligament, and posteriorly by its pubic portion : both externally and internally it is bounded by the junction of these two portions of fascia. Gimbernat's liga- ment, which is usually described as forming the internal boundary of the crural ring, rarely fills up more than half the space between the crest of the pubis and the femoral vein. This canal, as being composed of fascia, is firm, and un- yielding : it cannot be influenced by the actions of any muscle in the neighbourhood, nor even so much as is generally supposed by the posi- tion of the limb. It should follow from this constitution of parts that any hernia thus re- strained should forcibly compress the vein and artery before it suffered strangulation itself, and so it would if the protrusion had relation to this canal alone, and was not contained within its own proper portion of the funnel-shaped sheath already described. The neck of the sac of a femoral hernia, then, has behind it the fascia iliaca and the ligamento- cartilaginous material that covers the sharp edge of the linea ileo-pectinea : internally it has the junction of the fascia iliaca and transversalis, the attachment of the fascia lata to the linea ileo-pectinea, and Gimbernat's ligament; inter- nally it must also have the spermatic cord in the male and the round ligament in the female; anteriorly it has the fascia transversalis and Pouparl's ligament, and immediately above the neck and in close contact with it is the sper- matic cord, of course including the spermatic artery : externally is the membranous slip in- terposed between it and the femoral vein. The epigastric artery is also external to it, but although this vessel is somewhat irregular both in origin and position, yet the full breadth of the vein must be always interposed between it and the neck of the sac. But there is an irregular vascular distribution that must be borne in mind. In a great number of subjects (perhaps one out of every four or five) the obturator artery, instead of coming oft' from the internal iliac, arises by a common trunk along with the epigastric, which it soon leaves, and passing downwards and inwards crosses the superior aperture of the femoral canal before it dips into the pelvis to reach the obturator Foramen. In this course it sometimes passes the border of the canal posteriorly, but much more frequently in front; and in this latter case, if a hernia existed, the vessel would embrace two-thirds of the circle of the displaced peri- toneum close to and immediately above the neck. It appears, then, from these anatomical relations that in all subjects a considerable degree of danger may arise from too free and unguarded a use of the knife in operation — a danger that is necessarily enhanced in the male subject : indeed in consequence of the risk of haemorrhage Scarpa seemed disposed to trust to dilatation and laceration ot Poupart's ligament for relieving the stricture, and where these means were insufficient he recommended a new and particular direction to be given to the incision. But from caieful dissection and ex- amination of these parts I am disposed to believe there is always sufficient space to free a stricture without endangering either the sper- matic or the irregular obturator artery. It must be recollected that if the intestine is sufficiently liberated to permit the passage of gas through the immediate seat of the stricture, its return is perfectly practicable, and a very small incision will be sufficient to accomplish this. Now these vessels lie, not on the neck of the sac, but above it ; and there is quite space enough to set the stricture free without interfering with them : when they are wounded, it is in consequence of the introduction of the cutting edge of the bistoury too far within the stricture. When a portion of intestine has escaped through the femoral ring, (and by reason of the small size of the aperture hernia here are seldom large,) it lies at first within the crural canal, where it is restricted by the fascia lata, and its existence recognized with difficulty. Jt has happened that patients have perished from the incarceration of a small fold or knuckle of intestine without the circumstance ever having been discovered during life. But after it has passed the crescentic edge of Key's ligament, and is relieved from the pressure of the fascia, it comes forward, and if it increases farther, its direction is rather inwards and upwards, so that it may assume the position of an inguinal hernia to the extent of being mistaken for it. Having proceeded so far, the hernial sac has assumed somewhat of the form of an arch : it has passed, first downwards through the femoral canal, then forwards under the sharp edge of the fascia lata, either passing through the weak cellular portion of it or pushing it before, and then upwards and inwards in front. The hollow of this arch looks upwards, and is occupied by the crescentic edge of Hey's liga- ment. Perhaps this particular position of the hernia, as well as the extreme straitness and un- yielding nature of the crural canal, has con- tributed to the frequency of strangulation to which this form of hernia is liable. When a person stands erect and without exertion, Poupart's ligament forms nearly a direct line between the anterior superior spinous process of the ileum and the crest of the pubis, and all the fasciae connected to it are in their natural state and sufficiently relaxed ; but if the thigh is strongly extended or the body bent backward, the ligament then becomes tense and is arched backward toward the thigh. The effect of the general tension of the limb in this position would be to convert the arch formed by the hernia into an angle, against the hollow of which the edge of Hey's ligament would be firmly compressed, and a sufficient degree of resistance thus created to the return of the venous blood to produce a congested condition of the viscus. The operation of such a cause as this can hardly be considered as permanent, but the mischief once commenced is not easily controlled, and an intestine might soon be placed in such a condition as to render incar- ceration at the ring inevitable. The situations at which crural hernia may be strangulated have not been satisfactorily described, although there is no subject on which more anatomical labour has been bestowed. If HERNIA. 759 I was to speak from my own experience alone, I should say that though the hernia itself is superficial, the seat of the strangulation is always deep — somewhere at or in the imme- diate neighbourhood of the neck of the sac. I found the opinion partly on the dissection of subjects that had died of the disease, but more particularly on the phenomena I have observed during the progress of an operation on the living: still the experience of one individual can scarcely ever be sufficient to establish a great pathological principle, and there is autho- rity that cannot be questioned for believing that crural hernia is frequently strictured at a far less depth from the surface. Besides the neck of the sac, by which this hernia is con- fessedly strictured in very many cases, Sir A. Cooper places the seat of strangulation, first in the crural sheath and semilunar or lunated edge of the fascia lata, and secondly in the posterior edge of the fascia lata.* Mr. Colles says that the neck or constricted part of crural hernia does not always appear at the same depth from the surface, and explains the cir- cumstance thus : "The hernia having descended into the femoral sheath, it escapes through one of those apertures in it for transmitting the lymphatic vessels, and also passes through a corresponding opening in the iliac portion of the fascia lata. As it passes through a small aperture in each of these parts at nearly the same spot, it must there be liable to great con- striction ; for these two layers of fascia will be compressed together, and thus their strength and resistance be considerably augmented. Hence we should find the seat of stricture in strangulated femoral hernia frequently to be at some distance below and to the pubic side of the crural ring."f The descriptions of Hey and Burns I cannot profess clearly to understand, and I fear they were taken rather from sound subjects than from those in which herriiae were actually present. Scarpa does not distinctly point out the anatomy of the seat of stricture, but from the general bearing of his descriptions, and above all from the anxiety he expresses relative to the danger of wounding the sper- matic artery in operation, which vessel, if pre- sent, must lie close to the neck of the sac, I would hazard an opinion that he believed the seat of strangulation to be always deeply seated. In dissecting this rupture from without, or in operating upon it in the living, it will be found to lie at a different depth from the sur- face, and to possess variety in the number of fascial coverings according to its position with reference to the parts already described. Thus it may be placed within the crural canal, within that triangular space formed by the fascia lata ; or having passed beyond its inferior opening or falciform edge, it may present more superficially. In the former case, after the division of the common integuments, the skin and fat, the superficial fascia is exposed and may consist of many layers — at all events * Cooper on Hernia, part ii p. 14. t Colics' Surgical Anatomy, p. 77. of two : next is the dense and resisting fascia lata of the thigh ; and deeper still, the funnel- shaped fascia in which the crural ring is situated. Between this latter and the sac another fascia has been described under the name of the fascia propria, which may be supposed to be formed by a condensation of that cellular tissue already described as occupying the crural ring ; but I have never been able to satisfy myself as to the existence of this as a distinct membrane, and I must again caution the young operator not to expect to meet with laminse of fascia as de- scribed or demonstrated by the anatomist. A dexterous and careful dissector may make al- most as many layers of fascia as he pleases. After it has passed the inferior border of the crural canal and appeared more externally, the coverings of fascia to be expected must depend on the view taken of the anatomy of this part. If it is believed that the hernia having cleared this point merely swells out on being relieved from the pressure, without passing or pushing through any of the superincumbent structures, then in order to come down upon the sac it would be necessary to divide the skin and cellular tissue, the different lamina? of the fascia superficialis, the cribriform portion of the fascia lata, the anterior portion of the funnel-shaped fascia, and the fascia propria. If, on the other hand, it is supposed that the hernia has escaped through one of the openings in the femoral sheath, and a corresponding one in the iliac portion of the fascia lata, it will lie more super- ficial by the absence of these investments. In either case the last layer of fascia most adja- cent to the sac is almost always remarkable for density and strength. The general symptoms of this affection are the same with those of inguinal, such as the appearance of the tumour, its diminution or disappearance in the recumbent position, and the impulse imparted to it by coughing, sneez- ing, &c. : its peculiar symptoms are explicable by its anatomical relations. 1. The crural hernia is generally small and its increase slow : the size of the ring and the compression ex- ercised on it by so many superincumbent layers of fascia will be sufficient to account for this, and also will shew why this rupture is almost always painful, and why position has so much effect on it, relief being constantly ob- tained by bending the thigh on the pelvis and rotating the limb inwards. 2. The peculiar manner of growth, its first passing downwards, then forwards, and then upwards and inwards, is caused by the attachment of the funnel-like fascia to the vessels at the superior part of the thigh, and by that of the fascia supeificialis to the fascia lata near the entrance of the saphena vein ; thus its shape is never pyramidal like that of inguinal ; it is globular or oval, and its longest diameter is transverse. 3. I have already mentioned its prevalence amongst females advanced in life. As the testicle is more subject to disease than any structure at the top of the thigh, there are more affections with which scrotal hernia may be confounded; but on the other hand, when a doubt arises on the subject of crural 760 HERNIA, hernia, the diagnosis is vastly more difficult, and often the surgeon has to be guided by the gene- ral symptoms of peritoneal inflammation rather than by the results of local examination, how- ever carefully performed. Mr. Colles* states that "this species of hernia is liable to stran- gulation even before it can be felt externally," — an observation I was enabled to verify a few months since in a case where a very small knuckle of intestine had not passed the inferior aperture of the femoral canal, but was lodged in an absorbent gland, which seemed to have been hollowed out to receive it.f But the hernia may be much larger and still not disco- verable in consequence of some unfortunate complication : I have seen a case of incarce- rated hernia J in which an abscess was seated at the superior part of the thigh immediately in front of the sac ; and after the pus had been evacuated, some time elapsed before decisive symptoms pointed out the existence of the more formidable disease behind. There is, in the Museum in Park-street, a preparation exhibiting a fatty tumour growing on the exter- nal surface of a hernial sac. The patient from whom it was taken was the subject of opera- tion, and after the integuments and fascia had been divided and this tumour presented, some doubts were at first entertained as to the pre- sence of a hernia beneath it; but on careful examination the operator discovered the hernial tumour, and cutting cautiously through the other, opened the sac, in which a knuckle of intestine was found incarcerated. The opera- tion was successful, and the patient recovered. " In many instances," says Mr. Colles, " the difficulty of discriminating the disease is consi- derably increased by an enlarged lymphatic g'and lying anterior to a very small hernia." Perhaps there are no two affections more liable to be mistaken for each other than crural hernia and an enlarged lymphatic gland; and however apparently distinct the two affections may be, and however easy it may seem to form a diagnosis in theory, still the best surgeons speak of the difficulty of discriminating between them, and many acknowledge having fallen into the error themselves. It has happened that a patient has had a hernia on one side and an enlarged gland on the other, and when symptoms of strangulation became urgent, it was the gland that was considered to be the most pressing, and it was selected for the opera- tion. I recollect two cases which occurred nearly at the same time ; one in which there was a very minute hernia at the left groin, which had been regarded as a swelled gland, and the patient died of the effects of its stran- gulation ; the other a case of pure peritoneal inflammation, in which the patient happened to have a swollen gland in the groin, which was actually cut down upon and exposed, but the operation did not much injury, for the patient * Op. citat. p. 83. t This curious case occurred in the Meath Hospi- tal in the summer of 1835. | I use this term in the sense hitherto employed, not implying perfect strangulation. subsequently recovered. It has been said that a diagnosis can be established by attention to the following circumstances. The hernia fol- lows on some sudden exertion, on a blow or a fall, and appears suddenly and at once ; whereas the gland in the commencement is very small, perhaps like a moveable kernel, and increases slowly and by degrees. Besides, this diagnostic will be greatly assisted if there is a chancre or other sore to account for the irri- tation and inflammation of the gland; but on the other hand the hernia does not always- assume its given size at once, it is often so small at the beginning that the patient is not aware of its existence, and so far from appear- ing suddenly after a violent exertion it may have been present for months without being perceived. The hernia receives an impulse from coughing or sneezing, and retires or be- comes smaller in the recumbent posture, which are not observed to happen with the gland ; but then an enlarged gland may be complicated with a hernia, and the symptoms so mixed and confused that a diagnosis may be very difficult. It is said that a gland maybe moved about and withdrawn from its situation in a slight degree, and if it can there is no great danger of mis- taking it ; but when it has arrived at the size or occupies the place which could make it resem- ble a hernia, then it does not admit of being moved under the fascia, and the diagnosis is almost impossible. Fortunately, a crural hernia does not often consist of omentum, but when it does there is nothing more likely to exhibit the characters of a gland in a state of chronic dis- ease, and I know not how the two cases can be accurately distinguished. Here the physical evidence derived from a gentle percussion (as already noticed) is utterly and completely valueless. Lumbar or psoas abscess is another affection that may be confounded with femoral hernia, and Mr. Colles states that he had known the mistake to have been committed. These diseases resemble each other in the following circum- stances. Both present very nearly in the same situation at the bend of the groin, are firm and elastic; coughing gives to each the same or a similar impulse; and there are cases on record in which psoas abscess disappeared under pres- sure or by the patient assuming the recumbent posture. Yet I think the two cases not very difficult of distinction. Psoas abscess is a dis- ease of youth; it does not often occur in the adult except as a critical abscess after fever, or in connexion with caries and curvature of the spine, in either of which cases the collateral circumstances will point itout ; whereas femoral hernia is the disease of married women, and of course will not be likely to occur at the same period of life with the abscess. A sense of fluctuation is generally perceptible in psoas abscess ; not so with hernia. The abscess is preceded by pain and weight in the loins and by shivering. It is a scrofulous complaint, and there will probably be other indications of the diathesis, such as the transparent skin, the thickened upper lip, or perhaps ill-conditioned scars about the neck. Any of these symptoms HERNIA. 761 taken singly may prove but an indifferent dia- gnostic, but in the aggregate they establish such distinction that it must be the result of sad in- attention or of actual ignorance if any serious mistake is committed. It has been stated that a varix of the saphena vein may present symptoms and appearances strongly resembling crural hernia, inasmuch as the tumour disappears under pressure or in the horizontal posture, and returns again imme- diately on these influences being removed, and also as it receives a certain degree of impulse from coughing or sneezing. From anatomical considerations it would almost seem impossible that such an error could be committed, and at first sight the observation seems to have been made for the purpose of creating nice distinc- tions and rendering the subject apparently com- plete rather than for any practical utility. A case, however, is related by Petit, who distin- guished the real nature of the tumour by its dark-coloured appearance and by the general varicose state of the remainder of the vein. If difficulty is experienced in any particular case, it may be easily resolved by making pressure on the trunk of the iliac vein above Poupart's ligament, when the tumour will re-appear, even although the patient maintains the horizontal posture. " Fatty tumours are not unfrequently found on dissection occupying the exact situation of crural hernia. I have not had an opportunity of seeing any case of this kind in the living body, but have had occasion to remark at least five or six instances of it every season in the dissecting room, from which I presume such tumours are more common than is generally suspected. In all those instances the fatty tu- mour was connected with or rather seemed to grow from the outer surface of the peritoneum lining the crural ring; and the inner surface of this membrane when viewed from the abdomen had a contracted, wrinkled, and thickened ap- pearance, resembling very closely the appearance of a reduced hernial sac. Whether the perito- neum had been protruded in these instances I cannot pretend to say ; nor can I venture to lay down the symptoms which should guide us in our diagnosis in the living body. This much at least is obvious, that these steatoma- tous tumours will not be accompanied by symptoms of strangulation."* Umbilical hernia. — The navel is the remnant of an aperture that had been situated nearly in the centre of the front of the belly, but nearer to the pubis than to the ensiform cartilage: it is placed in the lmea alba, and of course its edges are tendinous. During foetal life it serves for the transmission of the umbilical vein and arte- ries, but its size is greater than would merely suffice for the passage of these vessels, in order that the circulation of the blood through them should suffer no interruption by accidental com- pression ; and in a foetus of seven months the edge of the aponeurotic opening is still thin, weak, and unresisting. After birth, when the * This passage is copied from Colles's Surg. Ana- tomy, p. 84. navel string (as it is called ) has dropped off, the umbilical aperture begins to close, until finally that puckered cicatrix is formed, the appearance of which is so familiar; but the periods at which this process commences and is completed, and the circumstances that may occur to interfere with it, are of some importance with reference to the phenomena of hernia. Scarpa says that it begins immediately, and that if the finger is passed up the peritoneal wall of the abdomen in a child two months after birth, not only will the navel be found firmly formed and completely cicatrised, but there will be a knot or elevation felt at this spot, shewing that it is then really stronger than most other parts of the abdominal parietes Lawrence states that the contraction commences about the third or fourth month after birth, and thence inculcates the necessity of an infant being tolerably accu- rately bandaged anterior to that period in order to prevent the occurrence of umbilical rupture from its struggles or its cries. It is not of much consequence which of these opinions may be correct : probably both are so to a cer- tain extent, for the opening is larger in some infants than in others, and will require a longer time to close, and the process of obliteration does not commence in all exactly at the same period after birth. Whatever variety may exist in this respect, when the process is com- plete the umbilicus can never afterwards be called an aperture; it never again re-opens; and when ruptures are observed in after-life seem- ing to occupy this situation, it will be found on examination that some neighbouring parts of the linea alba have given way, and the disease more strictly belongs to the ventral than to umbilical hernia. It appears then that by the salutary provi- sions of nature the front of the abdominal pa- rietes is well supported, and the contained viscera protected from protrusion ; and even if the operations by which the umbilicus is closed should be accidentally suspended or interfered with, (as by the presence of a hernia for in- stance,) the disposition is not lost, and the aper- ture preserves its tendency to close and become obliterated for the first five or six years of childhood. Thus at any time within that period there may be a reasonable probability of obtain- ing a permanent cure of umbilical hernia; whereas after the age of ten or twelve years this disposition ceases to operate, or at least is greatly impaired, and there is little or no chance of so fortunate an occurrence. The condition in which the umbilicus exists at and after birth divides the hernia? that occur in this situation into different orders according as they may appear at the period of birth or afterwards. Scarpa considers the disease to consist of only two species, the congenital and the adventitious — the congenital being that which appears in the infant when born, and the other occurring at any subsequent period. Lawrence speaks of three kinds, the congenital, that which appears at birth, and in which the protruded viscera are lodged in the umbilical cord; the umbilical hernia of children occur- ring after the navel has been formed, but pro- 702 HERNIA. trading through the original deficiency in the linea alba ; and the hernia of adults, which has some peculiarities that shall be noticed here- after. The congenital umbilical hernia seems to depend rather on a deficiency of the anterior walls of the abdomen than on any other cause, and in the cases in which it is observed, the aperture at the navel is much larger than it should naturally be, and its tendinous edges excessively thin and weak. The deficiency of the abdominal parietes ranks amongst natural malformations, and it is astonishing to what an extent it has been observed. The entire of the tendinous front of the belly has been found imperfect, and nearly the whole of the viscera displaced, thus forming an immense rupture covered at its base and for some extent farther by the skin and superficial investments of the body, and in its remaining part by the transpa- rent spongy substance of the umbilical cord. The contents of these ruptures are greatly varied : the liver or a portion of it, the spleen, the stomach, the greater and the lesser intestines have all been occasionally found thus circum- stanced, but more particularly the omentum, which, as might be anticipated from its situation, is observed to constitute a part of almost every umbilical hernia both in the old subject and in the young. Whenever there is such a defi- ciency in the abdominal parietes, the pressure an infant undergoes in coming into the world materially contributes to the production of hernia, and accordingly it is observed most fre- quently after a protracted and difficult labour ; and if it is large, and the contents of the ab- domen extensively deranged or displaced, it is in general fatal, the infant seldom surviving beyond two or three days, and perhaps not so long. In this affection there seems to be a want of correspondence between the size of the viscera and that of the abdominal cavity, the former appearing enlarged and swollen ; and there is seldom a possibility of returning the rupture, or of maintaining it so if reduced. There is in general also in these cases some other malformation or incomplete development to account for the fatality that so uniformly attends them. But if, on the other hand, the hernia is small, the case is by no means neces- sarily attended with danger : the rupture may be reduced, but it has a tendency to return when- ever the child cries or makes any other exertion, and it is extremely difficult to restrain it by a bandage ; but if it can be kept up for a few months, the umbilical aperture closes as it would have done if there had been no pro- trusion, and the cure is permanent and com- plete. If, before the navel has become cicatrized and closed, a portion of any vistus should happen to be protruded through it, and its progress towards obliteration thus interrupted ; or if the contraction has been delayed longer than usual, and an aperture thus left ready to favour the escape of a part of intestine from its natural situation, the rupture will be of the second form mentioned, namely, the umbilical hernia of the child. This differs from that of the infant inasmuch as it is covered by the skin and the cicatrized knot of the navel, and does not lie within the cord ; and from that of the adult, so far as, if replaced and prevented from again protruding, the aperture will gradually contract, and thus a permanent cure be obtained, which is scarcely to be expected at a more advanced period of life. It has been already mentioned that Scarpa considered the perfect contraction of the umbilicus to be completed in about two months, and at the end of that time that it is even firmer than other parts : he moreover seemed to think this part materially strength- ened by the remains of those vessels which before birth made up a part of the cord. The umbilical vein passing from the navel upwards towards the liver, and the hypogastric arteries passing downwards, are at the umbilicus united by a cicatrix to the skin and to each other, and contnbute to prevent the yielding of the part as soon as they become ligamentous. The point of union of these vessels must be pushed forwards as well as the integuments in adven- titious hernia, and hence it happens that when the umbilical aperture is only of its natural size, the rupture that takes place (if any) is small ; and in cases where it is large and the abdominal parietes deficient in this point, the tumo ur is flatter and more compressed than might have been otherwise expected, and some of these vessels are found lying on it and forming a part of its covering. In persons more advanced in life in whom the opening in the tendon had been perfectly closed, Scarpa denies that it ever becomes relaxed again, and therefore states that the rup- tures which occur from over-distension, from pregnancy, or as the sequels of dropsy, are not situated in the original umbilical canal, but in some part of the linea alba that has more recently given way, and of which the umbilicus happens to form a part. He states further that the linea alba is not equally strong and firm in all its parts ; that above the navel it becomes gradually thinner, and in women who have borne many children it is uneven in consistence, and in some parts so weak as to be liable to yield and tear on a very slight exertion. Hence it happens that these ventro-umbilical ruptures generally occur rather above the navel; and the almost obliterated remains of this cicatrix (for by the distension it becomes nearly smooth) is scarcely ever observed to occupy the centre of the tumour, but is found to one side and almost placed inferiorly. In the dissection of these tumours a laceration or fissure is constantly met with in the linea alba, sometimes transverse, but more generally longitudinal, and this is one reason why the umbilical ruptures of old per- sons are not susceptible of a radical cure, for there is a great difference between a natural opening, the tendency of which is to contract and close, and one made by the yielding and laceration of part of the linea alba or other tendinous portion of the abdominal parietes, which certainly cannot be supposed to be en- dowed with strong reparative properties. There was a question formerly raised as to whether umbilical hernia possessed a peritoneal HERNIA. 763 sac, and it was generally believed that no such investment had any existence in the disease. Garengeot in his paper on singular species of hernia? expressly states that ruptures of this kind were deficient in this particular, and he was followed by Petit and almost all the elders of our profession, who, to spare themselves the labour of investigation, copied from each other errors as well as truth. It is really curious to observe how a mistake could have so long maintained its ground that could have been set at rest by half-an-hour's dissection; and indeed it is in some respects surprising how such an opinion came to be entertained at all. In every case of umbilical hernia there must of neces- sity be a sac, because the peritoneum is not deficient at the navel, and the vessels that pass within the cord do not enter the cavity : they lie anterior to it, and are partly invested by the membrane, which is entire and complete behind the navel, and neither intestine nor omentum can be protruded without pushing it out before it, and thus constituting a proper hernial sac. It may be that in large umbilical hernia? the peri- toneum shall have become very thin, so that the peristaltic motions of the intestines may be easily perceived through it from without; or it may have been burst accidentally, and in either of these cases there will be an appearance as if there had been in reality no sac. And more- over, the peritoneum immediately behind the navel is not connected to it by the same loose and distensible cellular tissue that unites it to other parts : it is here very closely joined, and consequently in small ruptures only occupying this spot there will be no appearance of a sepa- rate and distinct sac, although the peritoneal covering is really there notwithstanding. It must be borne in mind, however, that invest- ments of umbilical ruptures are always very thin, and a proportionate degree of caution is requisite in cutting through them during ope- ration. There are no distinct layers of fascia here as in other ruptures, no lamina; to sepa- rate one by one and one after another. In the congenital species the contents of the sac are merely covered by the peritoneum and the sheath of the cord. In the infantile, the coverings are the skin and cicatrix of the navel and the peritoneum ; and in the adventitious kind or ventro-umbilical we meet the skin, then the superficial fascia, which is very thin and weak on this part of the abdomen; next the cellular tissue that had united the peritoneum to the adjacent structures, and which may have become condensed so as to form a kind of fascia propria; and lastly, the peritoneum or hernial sac itself. In almost every case of umbilical hernia occurring in the adult, omentum has formed part of the contents of the sac, at least the ob- servation has been so universally made that the rule may be considered as established. In general it lies before the intestine in such a po- sition as to conceal it altogether and make it appear as if no other viscus was engaged ; but sometimes the intestine makes a passage through it and presents first when the sac is opened ; or both these structures may be coiled and twisted together in such wise as to render it difficult to unravel and separate them one from another, and highly perilous to return them in that con- dition into the cavity lest strangulation should take place within. From the circumstance also of containing omentum, umbilical ruptures frequently become irreducible, this structure, when protruded, becoming thickened and en- larged and occasionally loaded with fat, so as to preclude the possibility of its being again returned through the tendinous opening. Or adhesions may have formed between the omentum and the intestine, or between either or both of these and the sac : in short, the rupture may become irreducible from any of the causes already mentioned as capable of producing such a condition of parts, but the one first alluded to, namely, the thickening and alteration of the omentum, is the one most generally observed. This altered condition of the omentum has also a paramount influence on the case even at a more remote period. Let it be supposed that symptoms of strangulation have supervened, and an operation been deemed necessary to preserve existence, the presence of this mass will be likely to prove extremely troublesome. Every surgeon is conversant with the different opinions that have been entertained as to the manner in which irreducible omentum should be dealt with. Some* speak boldly enough of cutting it off and returning any part that might remain, or allowing it to slip back into the abdomen without feeling any apprehension from the possibility of haemorrhage. Some have tied a ligature around it to cause it to slough, and Mr. Heyf employed a ligature in another way and with a different view, namely, by applying it so tight as gradually to cut through the omentum by the process of ab- sorption, but without entirely destroying the circulation through the included part. Scarpa| left the omentum, merely covering it with the sides of the hernial sac and dressing it lightly until suppuration appeared, when, he said, the pedicle by which it hung might be safely tied and the mass cut away. I notice this diver- sity of opinion not for the purpose of incul- cating any one line of practice, but to shew that the omentum cannot be left there with safety. It is at all times and under every cir* cumstance not very highly organized or able to sustain disease; still less so is it when altered from its natural arrangement, converted into an unwieldy mass of fat, and exposed to the in- fluence of the atmosphere in an open wound. Sometimes it runs into tedious and unhealthy suppurations with profuse and wasting dis- charges ; more generally, if the patient is old and debilitated, into mortification, which may (if the subject lives sufficiently long) pass on to the unaltered omentum within the abdomen, nor cease until it has reached the stomach. * Pott, op. ciut. p. ! 6. Petit and Ponteau, Mem. de l'Acad. Royale de Chir. torn. vii. p. 338. Colles's Surgical Anatomy, p. 100. t In this he was anticipated by Morcau, M£m. de l'Acad. Roy. de Ohir. t. vii. p. 344. i Op. ckat. p. 420. ?64 HIBERNATION. The symptoms of umbilical hernia are easily understood by referring to those points in which it differs from ruptures situated else- where. In the infant the tumour appears long and thin, according to the quantity of viscera protruded through the aperture of the navel, and projects downwards on the belly : its coverings are almost transparent. In the more adult subject, if the patient is thin the tumour is of a pyriform figure, and when permitted to in- crease without restraint becomes very large and hangs pendulous towards the pubes. If he is fat it may form a less circumscribed swelling, broad and flat, apparently extending in every direction round the umbilical aperture. The sensation imparted to the finger is of a soft and doughy tumour slightly moveable under the skin, but sometimes in consequence of the presence of intestine in the rupture it may possess some elasticity. Occasionally, after an omental hernia has remained for years without producing much inconvenience, it sud- denly enlarges towards the centre and assumes a conical chape, the apex being soft and elastic, the base hard and more solid : in this case there has probably been a fresh protrusion of intestine which has burst through the omentum and requires instant attention, as so circum- stanced it is extremely liable to fall into a state of strangulation. The collateral symptoms, such as nausea, flatulence, colicky pains, &c, are more severe and more frequent in umbilical than in any other form of hernia, a circum- stance that has often given rise to the idea that the stomach formed some part of the protrusion, but perhaps it is unnecessary to resort to such a supposition, for probably the hernia? of the linea alba that have been described as con- taining part of the displaced stomach were in no wise different from ordinary umbilical ruptures as to their contents, for the omentum being protruded will be sufficient to account for every aggravation of symptom. When the hernia is strangulated, it is said that the symptoms are less severe and less urgent than in other species of ruptures, a cir- cumstance that has also been accounted for from its so often containing omentum alone. Sir A. Cooper states that more cases of stran- gulation occur in the seasons when green vege- tables are plenty than in others, which would seem to favour the idea of its being often caused by the use of flatulent or indigestible sub- stances. But (except with reference to pre- vention) it is of little consequence how it may be caused, or whether its progress is rapid or not. When once formed, it must be reduced ; and it runs its course with sufficient rapidity to render it extremely alarming. It has destroyed a patient in less than eighteen hours, and although such severity is not generally to be expected, yet in this or in any other kind of hernia the smallest unnecessary delay can never be justified. " Sometimes a small mass of indurated fat, situated between the peritoneum and its union with the aponeurosis of the abdominal muscles, makes its way insensibly through the separated fibres of the linea alba, and is at last elevated externally in form of a tumour which seems to have all the characters of an omental hernia. The existence of this species of tumour through the linea alba is not only a certain fact and de- monstrated by several observations made on the dead body by Morgagni, by Klinkosch and several others, but it is also proved that it makes its appearance in other parts of the linea alba besides that to which the umbilical vein corresponds internally. It may occur that a person in whom a similar small tumour has existed for a long time in the course of the linea alba may be attacked from a quite diffe- rent cause by violent colic, with nausea, incli- nation to vomit, and interruption to the alvine excretions. The surgeon, in similar circum- stances, is easily led into error," (and Scarpa committed the mistake himself,) " presuming that the tumour is a true incarcerated hernia of the linea alba, subjecting the patient to an ope- ration which has no connexion with the cause of the disease." Never having seen any similar tumour, I have copied the above passage from Scarpa : they are probably of the same nature with those described by Mr. Colles as occa- sionally presenting at the crural ring. The resemblance must be strikingly obvious to every reader. ( William Henri/ Porter.) HIBERNATION ; etym. hiberno, to win- ter, to pass the winter; syn. lethargy ; errone- ously, torpor; Fr. sommeil hivernal ; Germ. Winterschlaf and Sommerschlqf ; a term chiefly applied to express that condition in which cer- tain animals pass the winter season. How often have I been struck with admira- tion in observing how variously the Creator has provided for certain of the insectivorous tribes, the swallow and the bat, for example, against the period when the sources of their daily food are cut off, when spring and summer yield to autumn and winter, and insects disappear ! The first emigrates to a more genial climate where its nutriment still abounds ; the second sinks into a deep sleep, in which food is unnecessary, and which continues through the dreary season of cold and famine. It has not hitherto been distinctly ascertained to what extent the state of hibernation prevails in the animal kingdom; the bat, the hedgehog, and the dormouse, are the genera which present us with the most marked examples of this sin- gular physiological condition in this country ; to these the elegant authoress of " Sketches of Natural History " has added the water-rat and the wood-mouse, observing of the former — " And when cold winter comes and the water- plants die, And his little brooks yield him no longer supply, Down into his burrow he cozily creeps, And quietly through the long winter-time sleeps." But before we proceed to discuss this ques- tion of natural history, we must consider that of the physiology of hibernation. There is, in my opinion, an ultimate law of animal existence, which seems to regulate the different forms in which the different classes of animals present themselves. The quantity of HIBERNATION. 765 respiration is inversely as the degree of irritabi- lity of the muscular fibre, the former being marked by the quantity of oxygen consumed in a given time, ascertained by the pneumatome- ter,* the latter by the force of galvanism neces- sary to demonstrate its existence. The bird tribes have a high respiration and a low irrita- bility ; the reptiles have a high degree of irrita- bility and little respiration. This law obtains not only in the different tribes of animals, but also in the different stages or states of the same individual, the structural changes from one stage to another being always a change from a lower to a higher respiration, and from a higher to a lower degree of irritability, and the change of state, a change in the opposite direction : thus the changes from the egg to the bird, from the tadpole to the batrachian form, from the larva to the chrysalis and the insect condition, are changes in which, whilst a due ratio is con- stantly maintained, the quantity of respiration is augmented and the degree of irritability diminished; on the other hand, the physiolo- gical changes in the degree of activity in ani- mals, during sleep, for example, but especially in that remarkable change which is the subject of this article, the respiration is diminished whilst the degree of irritability is, pari passu, augmented. On what this susceptibility of change de- pends, and especially on what the power of taking on an augmented irritability depends, is at present unknown. But 1 think I may affirm that it is upon this power that the capability of passing into the state of hibernation reposes. I suppose that all animals have the faculty of sleeping; during sleep the respiration is slightly diminished, the irritability probably proportio- nately augmented — probably one ultimate ob- ject of this state of repose ; but the phenomenon has its appointed limit which it cannot pass. In certain animals, that limit is not so con- fined,— the quantity of respiration is still further diminished, the decree of irritability still further augmented, and the deeper sleep, or lethargy, of hibernation takes place. During this lethargy, the law of the inverse ratio of the respiration and of the irritability still prevails, and the animal merely puts on a reptile state in these respects. Were the respi- ration to be diminished without the appointed augmentation of the irritability, the heart would cease to be stimulated, and the animal would die, as in the cases of torpor and slow asphyxia; were the respiration augmented without the proportionate diminution of the irritability, the heart would be over-stimulated, and death would alike ensue, as in the case of a hiberna- ting animal too suddenly roused from its lethar- gy, and as (probably) in the case of an animal placed in pure oxygen gas. The difference between the hibernating and all other animals then is, an ultimate faculty of assuming an augmented degree of irritability of the muscular fibre- — a power possessed by all animals within certain limits, but by the hiber- nating animal beyond the usual limit. * See Phil. Trans, for 1832, p. 323. Sleep, however inscrutable in itself, is the connecting link between the two physiological states; a disquisition on hibernation is, there- fore, a disquisition on sleep — on profound sleep. It will shortly appear that one eminent philoso- pher has fallen into the error of assimilating different physiological phenomena by neglect- ing to take this fact into his consideration. Sleep and hibernation are similar periodical phenomena, induced by similar causes, leading to similar effects, and differing only in degree. Hibernation appears more extraordinary only because less familiar than sleep. Most animals are, in fact, naturally awake and asleep every revolving day, some being diurnal, others noc- turnal. But in summer the bat actually hiber- nates, loses its respiration, and with its respira- tion its temperature, acquires vastly augmented irritability, and presents the other phenomena of complete hibernation, regularly and periodi- cally every twenty-four hours ; and the hedge- hog and the dormouse present simiiar pheno- mena, only after other intervals. Sleep then is the first stage of hibernation. The faculty of passing into the second is iden- tical with that of assuming a greatly augmented irritability of the muscular fibre. Such are the results of my long attention to this interesting physiological question. Much error has arisen from viewing hibernation as a simple effect of cold. The influence of cold in inducing hiber- nation is merely its well-known influence in inducing sleep, concurring with the other causes of this condition. The direct effect of cold on the animal frame is, as I shall shortly have occasion to state particularly, totally different from hibernation. Hibernation is a physiolo- gical condition; the direct effect of cold, or torpor, is, on the contrary, a pathological and generally a fatal one. The term hibernation has usually been ap- plied to designate what its etymology implies, the condition in which certain animals pass the winter season. An error is, as I have already stated, involved in this view of the subject ; for the condition termed hibernation is not con- fined to the winter season. Cuvier observes, in speaking of the Tenrecs, " ce sont des ani- maux nocturnes qui passent trois mois de l'annee en lethargie, quoique habitants de la zone torride. Burguifere assure meme que c'est pendant les grandes chaleurs qu'ils dorment."* Hence the term Sommerschhif employed in Ger- many. It is plain too, from this circumstance, that the state of hibernation is not necessarily connected with a low degree of external tempe- rature, and we are surprised to find this cele- brated naturalist, whom I have just quoted, observing, " la seule condition de la lethargie est le froid et l'absence des causes irritantes." f I must repeat that hibernation is, in every respect, but the parallel of ordinary sleep, vary- ing only in force and duration. It is equally marked by an inexplicable periodicity ; it is equally modified by cooperating or opposing * Regne Animal, ed. 1829, t. i. p. 125. t Histoire des Sciences Natuielles, 1829, t. i. p. 280. 766 HIBERNATION. causes ; and it is equally manifested in its pe- culiar effects, only varying in degree and inten- sity. In giving a distinct idea of hibernation we must extend our views to the altered condition of each function in the animal economy, for this peculiar state is not limited to any special function or organ. It is, in fact, a treatise on physiology which should be written, compa- ring the state of each function and of each organ, in the hibernant or lethargic and in the active condition, a disquisition on sleep, indeed, in its various degrees, and in its effects in mo- difying the various functions. The first question then is, — what is sleep ? a question difficult, perhaps impossible, to an- swer, if we mean by it what is its nature or essence, but highly interesting to prosecute, if we mean what are its special phenomena and their mutual relations. In order to treat of sleep properly, I must first observe that, of the nervous system, of which it is primarily a modification, formerly divided into the cerebrospinal and the ganglio- nic, the first division must now be subdivided into the cerebral and the true spinal, the former being the exclusive seat of sensation, volition, &c. ; the latter, the special source of certain actions now designated excito-motory, and ob- served in the orifices, the ingestors, the expul- sors, the sphincters, &c. Now it is the cere- bral system which sleeps, the true spinal re- taining all its energies. From this enunciation of the primary fact in sleep, we may trace the whole of the pheno- mena of this singular condition. In the state of activity, the cerebral system exerts a peculiar and continual influence over the true spinal, which ceases during sleep. In this manner the functions of the latter appear impaired ; the re- spiration especially, and with the respiration the circulation, with which it always maintains a certain relation, becomes slower, irregular, and suspended at intervals. These phenomena observable in ordinary sleep are still more re- markable in the deep sleep or lethargy of hibernation or diumation. In order that the effects of hibernation may be traced in relation to all the functions of the animal economy, I must enter into a few brief details relative to the arrangement of these functions and the order in which I propose to notice them. The most simple and natural arrangement of the functions appears to me to be the following : — I. Sanguification. 1. The ingestion and > cc , rpi j ' * ■ t of food. 2. The digestion . . . . J „ r™ r ( a. of chyme. 3. The formation.... ^ 6fchJle. . , ( a. by the Iacteals. 4. Absorption | 6. bJ imbibition. 5. The organization of the blood. II. Respiration. - rrx, i .• S «• of oxygen. • 1. The absorption . . \ , f -; b B r (b. of nitrogen, &c. ••, a. of carbonic acid. 3. The results s a. augmented temperature. b. a direct ratio between the pulsations and respirations. c. an inverse ratio between the respiration and irrita- bility. 2. The exhalation ' " I b. of nitrogen, See. III. The Circulation. 1. The pulmonic. 2. The systemic. 3. The cardiac or coronary. 4. The hepatic. 5. The splenic. 6. The circulation as the ( a. of nutrition. carrier lb. of temperature. IV. Defcecation. 1. Re-absorption by the lymphatics. f a. by the lungs. « b. by the skin. 2. Excretion <* c. by the liver. J d. by the kidneys, v e. by the intestines. V. The Nervous System. 1. The cerebral, or the system of a. The sensations, the senses. b. Volition, spontaneous motion. 2. The true spinal or excito-motory, or the system of a. The orifices. b. Ingestion. c. Expulsion. d. The sphincters. 3. The ganglionic. VI. The Muscular System. 1. The irritability. 2. The motility. I proceed to trace the influence of sleep, and of the deeper sleep of hibernation upon these various functions, beginning with the former. I. Of sleep. — It was first ascertained experi- mentally by Messrs. Allen and Pepys, that the quantity of respiration is diminished in ordinary sleep.* The acts of respiration are obviously less frequent and less regular, being frequently suspended for a moment and renewed by a deep inspiration. The animal frame becomes more susceptible of the influence of cold. It is most probable that, during this condition, the irrita- bility of the muscular system is augmented, and that this is one of the final objects of sleep; experiments, however, are still wanting to establish a fact in reference to ordinary sleep, which is clearly proved in regard to the sleep of hibernating animals, and the deeper sleep or lethargy of hibernation. I shall now proceed to treat of the sleep of hibernating animals. II. Of the sleep of hibernating animals. — In the sleep of the hibernating animal, the respira- tion is more or less impaired : if the animal be placed in circumstances which best admit of observation, the acts of respiration will be found to have greatly diminished ; if it be placed in the pneumatometer, little alteration is * Phil. Trans, for 1809. HIBERNATION. 767 induced in the bulk of the air; if its tempera- ture be taken by the thermometer, it will be found to be many degrees lower than that of the animal in its active state ; if it be deprived of atmospheric air, it is not immediately in- commoded or injured. These facts I have observed in the hedge- hog,* the dormouse,f and the bat.J If other authors have not made the same observations, it is because they have not been aware how easily this sleep is disturbed. To walk over the floor, to touch the table, is sufficient, in many instances, to rouse the animal, to re-pro- duce respiration, and to frustrate the experi- ment. The bat, which is a crepuscular or nocturnal feeder, regularly passes from its state of activity to one which may be designated diwnation. The respiration and the temperature fail; the necessity for respiration is greatly lessened. During the summer of 1831, I carefully ob- served a bat in this condition. If it were quite quiet, its respiration became very imperfect; its temperature was but a few degrees above that of the atmosphere ; being placed under water, it remained during eleven minutes unin- jured, and on being removed became lively and continued well. I have more recently watched the habits of two hedgehogs, in a temperature varying from 45° to 50°. These animals alternately awake, take food, and fall asleep. One of them is frequently awake, whilst the other is dormant, and goes to sleep at a time that the other awakes, but without regularity. When awake, the temperature of each, taken by pressing the bulb of a thermometer upon the stomach, is about 95° ; when dormant, it is 4.5° ; that of the atmosphere being 42° or 43°. The duration of this sleep is from two to three days, accord- ing to the temperature of the atmosphere. On the 4th of February, 1832, the temperature of the atmosphere being 50°, both the hedgehogs were dormant, — the temperature of one was 51°, and that of the other 52°; on the succeed- ing day, the temperature of the atmosphere had fallen one degree, the temperature of one of the hedgehogs was 49°, whilst that of the other, which had become lively, had risen to 87°; on the succeeding day, the first had become some- what lively, and its temperature had risen to 60°, that of the other being 85°, and that of the atmosphere 47°. I have observed precisely the same alterna- tions in the dormouse ; except that this animal awakes daily in moderate temperatures, takes its food, and re-passes into a state of sleep, in which the respiration is greatly impeded, and the temperature little higher than that of the atmosphere. On the day on which the observations were made on the hedgehogs, the atmosphere being 49°, that of two dormice was 52° ; on the suc- ceeding day, the external temperature being 47°, that is, lower by two degrees, the tempera- * Erinacetis Europrrns. + Myoxua avpllanariiis. % Vespertilio noclula. ture of one of these dormice was 92°, and that of the other 94°; and only three hours after- wards, the temperatures were 60° and 70° re- spectively, with a slight appearance of lethargy. The hedgehog and the dormouse appear, in fact, to awake from the call of hunger, then to eat, and then again to become dormant, in temperatures which may be termed moderate. The bat, which could not find food if it did awake, does not undergo these periodical changes, except in the summer season. It ap- pears to me, from the most careful observation, that there is every degree between the ordinary sleep of these animals and the most profound hibernation. It is quite obvious, from these observations, that the ordinary sleep of hibernating animals differs from that of others, by inducing a more impaired state of the respiration and of the evolution of heat, with an augmented power of bearing the abstraction of the atmospheric air. This sleep probably passes into true hiberna- tion, as the blood which circulates through the brain becomes more and more venous, from the diminution of the respiration, and as the muscular fibre of the heart acquires increased irritability. It is absolutely necessary, in comparing the powers of hibernating and other animals, of evolving heat, accurately to observe whether there be any tendency to sleep. Mr. Hunter's and M. Edwards's experiments are deficient for want of this attention. Mr. Hunter, com- paring the common mouse and the dormouse, exposed to a very low temperature, observes, that the temperature of the former was " dimi- nished 16° at the diaphragm, and 18° in the pelvis ; while in the dormouse it gained five degrees, but lost on a repetition." * The ex- planation of these facts is afforded by the obser- vation, that when the dormouse increased in temperature it was " very lively," but that on the " repetition" it had become " less lively ;" the mouse was probably in a state of languor from apprehension or for want of food. M. Edwards omits to mention whether the hibernating animals, in his experiments, were disposed to be lively or dormant, or whether they had recently recovered from the dormant state. He does not even mention whether the experiments on the bat were performed in the evening, its period of activity, or in the morn- ing or day, its period of lethargy or diurnation. Without a particular attention to these points, no correct result could be obtained. The hiber- nating animal, in a state of vigour and activity, is a totally different being from the same animal disposed to become dormant. In order to perform this experiment in a satisfactory manner, the bat, for example, should be employed in the evening, when it has naturally awoke from its deep day-slumber, the hedgehog when it has awoke spontaneously to take food ; otherwise the disposition to sleep may explain the loss of temperature. We must hesitate, therefore, in subscribing to the follow- ing conclusion of M. Edwards: " No"« voyons * Animal (Economy, p. 114. 768 HIBERNATION. que les chauves-souris produisent habituelle- ment moins de chaleur que les animaux a sang chaud, et que c'est principalement a cette cause qu'il faut attribuer l'abaissement de leur tempe- rature pendant la saison froide. En comparant cette experience sur la chauve-souris adulte avec celles que nous avons faites sur les jeunes animaux a sang chaud, on y apercoit un rap- port remarquable ; ils ne produisent pas assez de chaleur pour soutenir une temperature elevee, lorsque l'air est a un degre voisin de zero. Mais il y a cette difference, que c'est un £tat passager chez les jeunes animaux a sang chaud, et qu'il est permanent chez les chauves- souris. " II est evident que les autres mammiferes hibernans doivent participer plus ou moins de cette maniere d'etre. Les faits que j'ai exposes suffisent pour nous faire considerer ce groupe d'animaux sous le point de vue suivant; qu'au printemps et en ete, dans leur ttat d'activite et de veille, lorsque leur temperature est assez elevee pour ne pas diflerer essentiellement de celle qui caracterise les animaux a sang chaud, ils n'ont pas la faculte de produire autant de chaleur; et tout en admettant que d'autres causes peuvent influer sur leur refroidissement pendant leur hibernation, il faut cependant l'attribuer en grande partie a cette particularite de leur constitution." * There are, in fact, these differences between the young and the hibernating animal: 1. the former cannot, when exposed alone to severe cold, maintain its own temperature ; if the lat- ter appears to be in the same case, it is only because it has become affected with its peculiar lethargy; in its state of wakefulness and activity it maintains its usual elevated temperature in the same manner as other adult animals ; 2. the young animal, in losing its temperature, be- comes affected, not, like the hibernating animal, with lethargy, but with torpor, a totally diffe- rent and a pathological condition which gene- rally proves fatal. I must conclude these re- marks by observing that I think the eminent physiologist whom I have quoted has assimi- lated the condition of the very young animal and the adult hibernating animal erroneously. The mere phenomenon of loss of temperature is the same ; but the rationale of this pheno- menon, its causes and its effects, are totally different. III. Of perfect hibernation. — I now proceed to treat of perfect hibernation, of its causes, and of its effects on the various functions which I have enumerated. My observations will con- sist principally of a detail of a series of obser- vations and experiments made in the course of the year 1831-1832, compared with the results obtained by other inquirers. I consider that there is one special cause of hibernation, — that law imposed by the Creator, according to which all animals become affected with sleep at some period of each revolving day, and the hibernating animal at some period of the revolving year. We have thus presented to us the phenomena of diurnal and nocturnal * Des Agens Physiques, p. 155. animals, and the winter-sleep and the summer- sleep of hibernating animals. Exposure to cold, not too severe, disposes to hibernation, as it disposes to ordinary sleep. Severe cold, on the contrary, first rouses the hibernating animal from its lethargy, and then plunges this and all animals into a state of fatal torpor. The absence of every kind of stimulus or ex- citant, and a somewhat confined atmosphere,* also conduce to hibernation. Every excitement, on the contrary, that of hunger, that of the sexes probably, tend to dis- turb this peculiar lethargy. It is in this man- ner that we explain the periodicity of sleep and hibernation, though there is probably also some hidden influence of the seasons, of the day or of the year, influences which have been traced by Dr. Prout and by M. Edwards in regard to the quantity of respiration. I now proceed to treat of the condition of the several functions in hibernation. The process of sanguification is, in some hibernating animals, nearly arrested ; in others, it is entirely so. There is much difference in the powers of digestion, and in the fact of omitting to take food, in the hibernation of different animals. The bat, being insectivorous, would awake in vain ; no food could be found : the hedgehog might obtain snails or worms, if the ground were not very hard from frost : the dormouse would find less difficulty in meeting with grain and fruits. We accordingly observe a remark- able difference in the habits of awaking from their lethargy or hibernation, in these different animals. I have observed no disposition to awake at all in the bat, except from external warmth or excite- ment. If the temperature be about 40° or 45°, the hedgehog, on the other hand, awakes, after various intervals of two, three, or four days passed in lethargy, to take food ; and again re- turns to its state of hibernation. The dor- mouse, under similar circumstances, awakes daily. Proportionate to the disposition to awake and take food, is the state of the functions of the stomach, bowels and kidneys. The dor- mouse and the hedgehog pass the faeces and urine in abundance during their intervals of activity. The bat is scarcely observed to have any excretions during its continued lethargy. In the dormouse and the hedgehog, the sense of hunger appears to rouse the animal from its hibernation, whilst the food taken conduces to a return of the state of lethargy. It has already been observed, that there are alternations be- tween activity and lethargy in this animal, with the taking of food, in temperatures about 40° or 45°. Nevertheless, abstinence doubtless con- duces to hibernation, by rendering the system * M. de Saissy observes, " la marmotte, que j'ai engourdie par deux fois differentes, ne l'a ete, je crois, que parceque je me suis avise, quand la re- spiration a ete bien affaiblie, de boucher le trou du couvercle. Ce n'a ete que de cette maniere que je suis parvenu a l'engourdir; car toutes les tentatives que j'avais faites avant out ete vaines." HIBERNATION. 7G9 more susceptible of the influence of cold, in inducing sleep and the loss of temperature. The hedgehog, which awakes from its hibernation, and does not eat, returns to its lethargy sooner than the one which is allowed food. The respiration is very nearly suspended in hibernation. That this function almost ceases, is proved, 1st, by the absence of all detectible respiratory acts ; 2dly, by the almost entire ab- sence of any change in the air of the pneuma- tometer ; 3dly, by the subsidence of the tem- perature to that of the atmosphere ; and 4thly, by the capability of supporting, for a great length of time, the entire privation of air. 1. I have adopted various methods to ascer- tain the entire absence of the acts of respiration. I placed bats in small boxes, divided by a par- tition of silk riband, the cover of which con- sisted of glass, and in the side of which a small hole was made to admit of placing a long light rod or feather under the animal's stomach. The least respiratory movement caused the extremity of this rod to pass through a considerable space, so that it became peifectly apparent. Over the hibernating hedgehog I placed a similar rod, fixing one extremity near the ani- mal, and leaving the other to move freely over an index. During hibernation not the slightest movements of these rods could be observed, although they were diligently watched. But the least touch, the slightest shake immediately caused the bat to commence the alternate acts of respiration, whilst it invariably produced the singular effect of a deep and sonorous inspira- tion in the hedgehog. It is only necessary to touch the latter animal to ascertain whether it be in a state of hibernation or not : in the former case there is this deep sonorous inspira- tion ; in the latter, the animal merely moves and coils itself up a little more closely than before. After the deep inspiration, there are a few feeble respirations, and then total quiescence. The bat makes similar respirations without the deep inspiration, and then relapses into sus- pended respiration. 2. As the acts of respiration are nearly sus- pended during hibernation, so are the changes induced in the atmospheric air. On January the 28th, the temperature of the atmosphere being 42°, I placed a bat in the most perfect state of hibernation and undis- turbed quiet, in the pneumatometer, during the whole night, a space of ten hours, from lh.30m. to llh. 30m. There was no perceptible absorp- tion of gas. Having roused the animal a little, I replaced it in the pneumatometer, and continued to dis- turb it from time to time, by moving the appa- ratus. It continued inactive, and between the hours of lh. 20m. and 4h., there was the absorp- tion of one cubic inch only of gas. Being much roused at four o'clock, and re- placed in the pneumatometer, the bat now con- tinued moving about incessantly ; in one hour, five cubic inches of gas had disappeared. It was then removed. A further absorption took place of -8 of a cubic inch of gas. Thus the same little animal, which, in a state of hibernation, passed ten hours without respi- ration, absorbed or converted into carbonic acid, VOL. II. 5-8 cubic inches of oxygen gas in one hour when in a state of activity. In an intermediate condition, it removed one cubic inch of oxygen in two hours and forty minutes. I repeated this experiment on February the 18th. A bat, in a state of perfect hibernation, was placed in the pneumatometer, and remained in it during the space of twenty-four hours. There was now the indication of a very slight absorption of gas, not, however, amounting to a cubic inch. On February the 22d, I repeated this expe- riment once more, continuing it during the space of sixty hours; the thermometer de- scended gradually, but irregularly, from 41° to 38°; the result is given in the subjoined table. External Absorp- Dura- Date Temperature, tion. tion. Feb. 22 11 P.M 41° 23 11 a.m 38$..** "8 12h 11 p.m 39± -75 12 24 11 a.m 38 .... -5.... 12 11 p.m 39 ....'75 12 25 11 a.m 38 -6 12 3-4 60 From this experiment it appears that 3'4 cubic inches of oxygen gas disappeared in sixty hours, from the respiration of a bat in the state of lethargy. It has been seen that in a state of activity, an equal quantity of this gas disap- peared in less than half that number of minutes. The respiration of the hibernating bat descends to a sub-reptile state ; it will be seen shortly that the irritability of the heart and of the mus- cular fibre generally, is propoitionably aug- mented. In this experiment it is probable that the lethargy of the animal was not quite complete. Should the temperature of the atmosphere fall, and continue at 32°, I shall again repeat it under these circumstances. The respiration will probably be still mote nearly suspended. It is important to remark, that the registra- tion of the quantity of absorption in these expe- riments was not begun until several hours after the animal had been inclosed within the jar of the pneumatometer, so that the absorption of the carbonic acid always present in atmospheric air was excluded from the result. It may be a question whether the slight quantity of respiration I have mentioned be cutaneous. The absence of the acts of respira- tion would lead us to this opinion. But it may be observed, that these acts have not been watched, and can scarcely be watched continu- ously enough, to determine the question of their entire absence. Some contrivance to as- certain whether the rod has moved along the index daring the absence of the observer would resolve every doubt upon this interesting point. And I think it right to remark, that after the apparent total cessation of respiration, as ob- served by the means which have just been de- scribed, there is probably still a slight diaphrag- matic breathing. I am led to this conclusion, by having observed a slight movement of the flank in a favourable light, unattended by any motion of the thorax or epigastrium. 3. Much precaution is required in ascertain- 3 £ 770 HIBERNATION. ing the comparative temperature of the animal with that of the atmosphere. The slightest ex- citement induces a degree of respiration, with the consequent evolution of heat. The plan which is best adapted to determine this question in regard to the bat, and which I have adopted, together with every attention to preserve the animal quiet and undisturbed, is the following : a box was made of mahogany, with a glass lid, divided horizontally at its mid- dle part, by a fold of strong riband, and of such dimensions as just to contain the animal. The bat was placed upon the riband, and in- closed by fixing the lid in its place. Being lethargic, it remained in undisturbed quiet. A thermometer, with a cylindrical bulb, was now passed through an orifice made in the box on a level with the riband, under the epigastrium of the animal, and left in this situation. This arrangement is made obvious by the subjoined wood-cut, (fig. 306,) which also displays the mode of examining the circulation. It was only now necessary to make daily ob- servations and comparisons between this ther- mometer and another placed in the adjacent at- mospheric air. The layer of silk, and the por- tion of air underneath, protected the animal from the immediate influence of the tempera- ture of the table, on which the box was placed. The following table gives the result of obser- vations made during many days, in very vary- ing temperatures. Temperature of Temperature Date. the Atmosphere, of the Animal. Jan. 6 11 p.m.. 40 40 J 7 8 p.m 43 43 8 41 41^ 9 11 p.m 47 46 10 10 a.m 46 46 — 12 midnight. .47 47 11 10 p.m 45 45 12 11 p.m 45 45 13 11 p.m 37 374 14 11 a.m 37 37 — 11 p.m 40 40 15 2 p.m 37 37 — 11 p.m 35 35 16 11 p.m 37 37 17 11 p.m 42 42 18 11 a.m 40 40 19 10 p.m 36 36 20 11 p.m 39 39 21 11 r.M 40 40 22 11 p.m 44 44 23 10 a.m 42§ 424 — 11 p.m 40§ 404 24 11 p.m 434 43| 25 10 p.m 42 42 26 10 p.m 41 41 27 10 p.m 37 37 28 11 a.m 344 344 — 11 p.m 37 37 29 11 a.m 42 42 — 11 p.m 43 43 30 11 p.m 42 42 31 11 p.m 394 39i From this table it is obvious that the tempe- rature of the hibernating animal accurately fol- lows that of the atmosphere. When the changes of temperature in the latter are slight, the two thermometers denote the same temperature. If these changes are greater and more rapid, the temperature of the animal is a little lower or higher, according as the external temperature rises or falls ; a little time being obviously re- quired for the animal to attain that temperature. Similar observations were made during the first three days of February. On the 4th, how- ever, the temperature of the atmosphere rose to 50§°; that of the animal was now 82°, and there was considerable restlessness. On the 6th, the temperature of the atmosphere had fallen to 474 , and that of the animal to 48°, whilst there was a return of the lethargy. After this period there were the same equal alterations of temperature in the animal and in the atmosphere, observed in the month of January. It is only necessary to add to these observa- tions, that the internal temperature is about three degrees higher than that of the epigas- trium. In two bats, the external temperature of each of which was 36°, a fine thermometer, with an extremely minute cylindrical bulb, passed gently into the stomach, rose to 39°. The following experiments, made by the celebrated Jenner, illustrate this point : " In the winter, the atmosphere at 44°, the heat of a torpid hedgehog at the pelvis was 45°, and at the diaphragm 48^°. " The atmosphere 26°, the heat of a torpid hedgehog, in the cavity of the abdomen, was reduced so low as 30°. " The same hedgehog was exposed to the cold atmosphere of 26° for two days, and the heat of the rectum was found to be 93°; the wound in the abdomen being so small that it would not admit the thermometer.* * The animal had become lively, on the Animal (Economy, p. 113. See Hunter HIBERNATION. 771 " A comparative experiment was made with a puppy, the atmosphere at 50°; the heat in the pelvis, as also at the diaphragm, was 102°. " In summer, the atmosphere at 78°, the heat of the hedgehog, in an active state in the cavity of the abdomen, towards the pelvis, was 95° ; at the diaphragm, 97°." * There is an error in the admirable work of M. Edwards, as 1 have already stated, in rela- tion to the present subject, which it is important to point out. M. Edwards first ascertained the interesting fact, that the very young of those species of animals which are born blind, lose their temperature if removed from the contact of their parent; and justly concludes that they have not sufficient power of evolving heat, to maintain their natural temperature when so ex- posed. M. Edwards then subjected hiberna- ting animals to the action of cold, and observ- ing that their temperature also fell, he concludes that they, like the very young animal, have not the faculty of maintaining their temperature under ordinary circumstances. f It is remarkable that this acute physiologist did not perceive the error in this reasoning. In no instance does the young animal maintain its warmth, when exposed alone to the influence of an atmosphere of moderate temperature. Can this be said of the hibernating animal ? Certainly not. In ordinary temperatures, the hibernating animal maintains its activity, and with its activity, its temperature. The loss of temperature in this kind of animal is an in- duced condition, occasioned by sleep. There is a point unnoticed in M. Edwards's experiment. It is the condition of the bat in regard to activity or lethargy under the exposure to cold ; and upon this the whole phenomena depend. The differences between the young animal benumbed, and the hibernating animal lethargic, from cold, are both great and numerous. I purpose to point them out particularly on a future occasion. 4. It is in strict accordance with these facts, that the lethargic animal is enabled to bear the total abstraction of atmospheric air or oxygen gas, for a considerable period of time. Spallanzani placed a marmot in carbonic acid gas, and makes the following report of the ex- periment in a letter to Senebier : " Vous vous ressouviendrez de ma marmotte qui fut si forte- ment lethargique dans l'hiver severe de 1795 ; je la tins alors pendant quatre heures dans le gaz acide carbonique, le thermomitre marquant — 12°, elle continua de vivre dans ce gaz qui est le plus mortel de tous, comme je vous le disais : au moins un rat et un oiseau que j'y placai avec elle y perirent a l'instant meme. 11 parait done que sa respiration fut suspendue pendant tout ce terns-la. Je soumis a la meme experience des chauve-souris semblablement lethargiques, et le resultat fut le meme." J * Ibid. p. 112. f Des Agens Physiques, p. 155. t Memoires sur la Respiration, par Lazare Spal- lanzani, traduites en Fran"J^*«~ Alexander Clarke, ret. 17, on admission into the Richmond Hospital, it was observed that there was much swelling about the hip-joint; the integuments over it were tense and shining, t ie glands in the groin were swollen and very tender; he suffered from pain, shooting to the knee and spasmodic startings, which awoke him at night; he could not permit the slightest motion of the limb, which was shortened one inch and a quarter; it was habitually inverted and flexed on the trunk ; the constitutional dis- turbance was considerable. From the treat- ment adopted he derived benefit, and a partial recovery resulted. He left the hospital, but soon returned, in consequence of an aggravation of all the former symptoms, caused by a fall on the diseased hip. A deep abscess formed in the groin and extended under Poupart's liga- ment; hectic symptoms showed themselves. There were alternate diarrhoea and attacks of vomiting. The abscess in the iliac fossa in- creased, the tumefaction around the joint dimi- nished, the shortening and inversion of the limb became greater, and oedema of the foot and leg occurred ; he now became suddenly insensible; his left arm was totally paralyzed, while the right was convulsed and constantly in motion ; his face too was distorted by twitchings, and he passed his discharges involuntarily ; he lay thus for several days and died, being in all eighty days ill. Post-mortem examination. — Upon cutting down to the hip-joint the capsular ligament was found to have been extensively removed ante- riorly; posteriorly and laterally it was not ulce- rated, but seemed to have been greatly length- ened and widened ; the synovial membrane was lined with a yellowish-green membrane, just like what we see investing the interior of the sac of an old chronic abscess ; the ligamen- tum teres and cartilage, which invested the head of the bone, had been removed, the bones were rough, unusually red and vascular, and were coated with yellowish-green lymph ; the acetabulum was much enlarged, and the head of the bone was drawn to the upper and outer part. The left iliac fossa was entirely filled by an immense abscess, lying between the muscle and bone, passing down under Poupart's liga-' ment as far as the lesser trochanter. The iliac vessels and the anterior crural nerve were pushed forwards ; half an inch below Poupart's ligament a process of the abscess had passed outwards and backwards, which communicated with the hip-joint, and having the muscles pos- terior to the joint, which were thinned and matted together, to form its wall in that direc- tion. In the brain purulent matter was found on the arachnoid surface as well as between the several convolutions of the right hemisphere. The neighbouring portion of the brain was softened and vascular; there was no effusion into the arachnoid sac or into the ventricles.* Sometimes the acute arthritis coxa is an essential disease, and the only one present at the time in the constitution, being simple and confined to the one articulation, as in the case of Reddy before quoted. Sometimes, however, the acute inflammation of the hip-joint is a symptom of another disease. In acute rheu- matic fever the hip-joint is, in its turn', some- times severely visited. Finally, the cases yet published of acute periostitis and synovitis combined, and of acute puerperal rheumatism, in which the hip-joint became implicated, need not be discussed here. We are of opinion that such cases should be looked upon as true spe- cimens of that almost intractable disease called diffuse inflammation. Anatomical characters. — FYom the post-mor- tem examinations of cases of acute arthritis coxae which have been hitherto made, we can collect that all the structures around the joint are in a state of active vascular congestion. The synovial membrane and subsynovial struc- ture present the ordinary characters of active congestion and the results of acute inflamma- tion. Sometimes there is an increased secretion of synovial fluid, and sometimes, in its stead, purulent matter distends the articulation. The synovial membrane, where it is reflected over the neck of the femur, has been found de- * See Dublin Journal, vol. iii. and iv„ also pre- paration in the Richmond Hospital Museum, which the writer has recently inspected. ABNORMAL CONDITIONS OF THE HIP-JOINT. 793 stroyed by ulceration. Sometimes the purulent matter has been known to have escaped from the articulation by ulcerated openings in the capsule of the joint, and to have passed into the pelvis, and penetrated between the muscles. The fatty mass at the bottom of the acetabulum has been found swollen, inflamed, and covered with a membranous layer of lymph, at the same time in some of these cases the neigh- bouring periosteum has been found detached from the bone, which was redder than usual. These are appearances which have been noticed in those who have died of acute arthritic in- flammation, whether it may have arisen from diffuse inflammation or simple acute disease confined to the one articulation. In acute cases, actual dislocation of the bones, we be- lieve, has not been noticed, as the disease seldom arrives at its second or third stage under such circumstances, but the cartilage and synovial membranes have been altogether destroyed, and the porous structure of the bones has been ex- posed, digital depressions have been seen pro- duced by acute caries in the acetabulum and head of the femur. The bones have then pre- sented'a rough vascular surface, and in many cases lymph has been found to cover the con- vexity of the head of the thigh-bone and to line the acetabulum. The head of the femur some- times is but little altered, either as to form or position, but when the acetabulum is largely excavated by disease, the head of the thigh-bone will be found to be drawn by the muscles to its upper and back part. Even in acute arthri- tis coxa in the young subject, the epiphysis of the head of the femur has been found de- tached.* The ligamentum teres is generally absorbed early, and the capsular ligament is usually ulcerated in some one part, so that, on the post-mortem examination, the bones are found to be very moveable on each other. They are usually observed to be highly vascular, and some imagine the head of the femur is en- larged. Ilyperosteotic depositions or stalacti- form productions, which are very friable, exist around the diseased joint. 2. Chronic strumous arthritis coxa. — The scrofulous disease of the hip-joint is very gene- rally slow in its progress, and is seldom seen, except in persons who bear other evidences of the strumous diathesis ; there are examples of it occurring in individuals who have passed the age of thirty years, though generally seen in those of more tender years. This affection of the joint, although slow and insidious in its attack, yet is attended with the usual pheno- mena of an inflammatory or sub-inflammatory action. Many of the writers who have de- scribed the " disease of the hip-joint," have assigned to it three periods or stages, as Ford has done, while succeeding authors have added to the description of the three stages of Ford, a period which they call the period of the inva- sion of the disease. In this their first stage, there is pain in the thigh, extending to the * See a preparation in the museum of the Col- lege of Surgeons, Dublin, presented by the lute Professor Todd. knee, which appears and disappears alternately; a marked weakness in the thigh, and a sense of feebleness in the whole limb; the gait is limp- ing, and some tension is felt in the groin. This period lasts sometimes but a few days, at other times many months. In the second period the limb is wasted, andapparently, though not really, elongated ; the trochanter is placed lower down, and is more outward than that of the opposile side; the buttock is flattened, and its fold is lower than natural ; the patient's lameness is characteristic; he moves the affected limb round with a shuffling motion, the foot scraping the ground, and he sometimes assists the eleva- tion of the thigh with his hand. At this time the knee is painful, and not unfiequently a puffy swelling appears in it, both which cir- cumstances often too much attract the attention of patient and surgeon, and divert it from the true seat of the disease. The third period is characterized by a real shortening of the limb ; this is sometimes sudden, and the im- mediate consequence of caries of the brim of the acetabulum and luxation of the head of the femur upward and backward on the dorsum of theilium. The shortening of the limb, however, is more commonly gradual, and the consequence of the slow ulceration and widening of the ace- tabulum. It has of late been truly observed, that the luxation is not so common as generally ima- gined, but when it does occur, it usually takes place in the direction upwards and outwards ; when the fibrous capsule and other ligaments are destroyed by ulceration, the head of the femur escapes by the superior and posterior part of the acetabulum, and obeying the action of the glutei muscles, it glides from before backwards and without inwards upon the con- ' vex surface of the ilium ; the thigh is flexed, adducted, and turned with a strong rotation in- wards ; the great trochanter approaches the' crest of the ilium, the muscles are raised up by the head of the femur, and the buttock is rounded, and becomes very protuberant poste- riorly. Although this is the direction in which the luxation usually takes place, still it has been noticed to have occurred in a direction horizontally backwards towards the ischiatic notch (Earle). It has also been seen in the direction downwards and inwards towards the foramen ovale, in which case the limb is elon- gated and directed outwards. Still more rarely has it been thrown upwards and inwards on the horizontal ramus of the pubis. In one in- stance, says Brodie, I have seen the dislocation in the direction forwards, the head of the femur resting on the pubis, the knee and toes being turned outwards. It would be wrong, however, to suppose that a true dislocation of the head of the femur from the ulcerated acetabulum is a very com- mon occurrence; although all these cases, above alluded to, have been witnessed, we be- lieve very frequently the shortening of the limb in the third and fourth stage of the disease arises from ulceration and widening of the ace- tabulum and destruction of the head of the femur. The head of the femur sometimes sepa- 794 ABNORMAL CONDITIONS OF THE IIIP-JOINT. rates at its epiphysis from the neck of the bone, and the latter is drawn up, (fig. 311,) and the Fig. 311. whole limb shortened greatly, and the toes are as much everted as when fracture of the neck of the femur occurs from accident. The short- ening is usually, but not invariably, the pre- cursor of abscess ; when this occurs, the disease is in its fourth stage. This period, or that of of the formation of matter, is generally marked by an aggravation of the pain, by frequent spasms and startings of the muscles, by greater wasting of the limb, occasional oedema of the foot, (which is a very unpromising feature,) &c. These chronic symptomatic abscesses may present themselves in various directions ; the matter may remain for months without under- going any change, and even after this be rather suddenly absorbed, or the pus may escape through openings made by nature or by art; the external orifices of these abscesses frequently degenerate into fistulas, from which exfolia- tions occasionally take place, and these exfolia- tions are sometimes so small as to be almost sabu- lous, sometimes larger pieces come away with pain ; such are to be considered not unfavoura- ble indications. The writer has known two ex- amples of the head of the femur thus separated at their epiphysis from the neck of the bones; in these cases the patients recovered, with the usual deformity.* Of the numerous situations around the hip-joint, in which matter has been found deposited, there is one variety which demands the special attention of surgeons, in conse- quence of the difficulty which has been expe- rienced in recognizing the disease, namely, the case in which the caries affects the bottom of the acetabulum, so that the fundus alone is de- stroyed. Sir B. Brodie met with one case, * One of these was presented to him by Mr. Shaw, the surgeon to the Clonard Dispensary, and is preserved in the Richmond School Museum ; the other was shewn by Dr. Carlile lately to the Patho- logical Society, Dublin. where in the bottom of the acetabulum there was an ulcerated opening, just large enough to admit a common probe, communicating with an abscess within the pelvis. Mr. Tagart* alludes also to a case in which this perforation exists. (Figs. 312 and 313.) Of such per- Fig. 312. Fig. 313. * Lancet, vol. i. 1SJ35 and 6, Jan. 2. ABNORMAL CONDITIONS OF THE HIP-JOINT. 795 forations the writer has seen in different mu- seums a great variety : in many instances the opening is small, in others of sufficient size to admit easily the head of the femur. These cases are in the beginning obscure, and when abscesses form, they are concealed within the cavity of the pelvis. Anatomical characters. — 'When opportuni- ties have occurred of examining the interior of the hip-joint in those who have died of other complaints, this articulation being, at the time of death, in the early stages of the chronic dis- ease we are now considering, the adipose cellular mass which occupies the fundus of the acetabulum, the cellular structure which con- nects the fibres of the inter-articular ligament, the subsynovial cellular tissue which surrounds the corona of the head of the femur, as well as the interior of the bones themselves, have been found to wear an unusually red appearance from increased vascularity. The cartilage has been found softened, to have lost its usual lustre, to be slightly elevated, and too easily torn from the subjacent bone ; in some cases thinned, in others detached in flaps; in some it has presented a corroded appearance, and coinciding with these changes purulent matter has been found in the interior of the joint, the capsular ligament thickened, and the lymphatic glands in the groin enlarged. In the anatomi- cal examination of those who have died in the advanced stages of the scrofulous disease of the hip, if the patient have not arrived at the age of puberty, we find that very frequently the original portions of the os innoirnnatum are separated from each other for several lines, that the epiphysis of the head of the femur is com- pletely detached from the shaft of this bone ; the greater and lesser trochanters are sometimes in very young subjects removed by absorption, and evidence of devastating caries is found in the bottom of the acetabulum. ( Fig. 311.) In some cases the head of the bone has been found dislocated on the dorsum ilii, previous to which occurrence all the ligaments have been destroyed, the acetabulum has the superior and posterior part of its brim removed by caries, and the bone thus abandoned to the action of the muscles takes the position it ordinarily does in the common luxation upwards and backwards on the dorsum ilii. This complete dislocation is not so common an occurrence as generally imagined ; there are, however, some specimens of it preserved in the museum of the College of Surgeons in Dublin. In one pre- paration, the cartilage of the head of the femur is perfect, the round ligament is gone ; the fur- ther ascent of the head of the bone on the dor- sum ilii seems principally restrained by the ob- turator muscles (fig. 314). The interesting circumstance in the preparation to be noticed is, that the acetabulum is occupied to the level of its brim with a very dense atheromatous matter or yellowish green lymph, apparently an uncganized substance resembling what we see contained in crude scrofulous tubercles : what remained of the capsular ligament around the neck of the femur has been cut crucially, and the everted edges of the flaps shew the thick- Fig. 314. ness of this ligament, increased to four or five lines, and caused by the interstitial deposition of something like atheromatous matter. We have in the foregoing pages alluded to the different directions in which the head of the femur has been found dislocated in the third or fourth stage of this disease, and should here state the anatomical characters of each luxation, but we have not facts to guide us in the de- scription. When a section is made of the bones enter- ing into the composition of the hip-joint, when the patient has died of this disease in an ad- vanced stage, they will be found to be softened in the interior, and to contain a fatty or a yel- lowish cheese-like matter in their cells ; when opportunities have occurred for examination in an earlier stage of this scrofulous caries, these organs have been generally found preternatu- rally red and vascular, (as before stated,) with a deficient proportion of earthy matter, admit- ting not only of being cut with a knife without turning its edge, but yielding and being crushed under very slight pressure. A modern au- thor,* after quoting the authority of Lloyd on scrofula as proof of the truth of some of the foregoing observations, adds his own opinion, " that in simple inflammation, uninfluenced by the scrofulous diathesis, particularly when it becomes of a chronic character, bone is secreted in abundance, but that the striking feature in this kind of inflammation is, the absence of all secretion or deposit of bone." With the latter doctrine we cannot at all agree, and must conclude we do not rightly apprehend the * Coulson on the Diseases of the Hip-joint, Load. 1837, 4to. p. 39. 796 ABNORMAL CONDITIONS OF THE HIP-JOINT. author, as we have very generally found osseous growths exterior to the hip-joint in the os inno- minatum and femur, {Jig. 310), as the result of scrofulous inflammation of the articulation. These growths are generally friable stalactiform productions which beset the bones, and are to be seen in the numerous specimens illustrating the morbid anatomy of morbus coxa?, which are contained in our museums in Dublin.* Notwithstanding these osseous productions or vegetations, the bones are found to have dimi- nished much in their specific gravity. I have always found them float when thrown into water. These growths are, however, only met with in the post-mortem examination of such chronic cases as have manifested in their course various alternations of improvement and re- verses ; they are almost invariably found when the caries of the bones had been arrested, and an imperfect attempt at anchylosis had been made. We have also opportunities of examining anatomically the hip-joints of persons who have had this disease in their youth, in whom it had been arrested in the second or third stage, and who had attained advanced life, and died of some other complaint. In some, besides the bony growths already alluded to, we find ex- amples of anchylosis or of a false joint ; indeed, although an absolute union and consolidation of the bones, viz. the os innominatum and the head of the femur may not have taken place, still in most cases there is very little real motion of the two bones upon each other ; the flexor and adductor muscles of the thigh and hip-joint are usually in a state of spastic contraction ; they admit of but little increase of flexion : whenever we attempt extension, we find the thigh is readily brought down from the abdomen, the lumbar vertebrae are arched forwards, and this portion of the spine and the sacrolumbar articulation are the seat of motion, which often is erroneously referred to the hip- joint. The os innominatum follows the head of the femur just as freely almost as the scapula accompanies the various changes of position impressed upon the humerus, when anchylosis of the shoulder-joint has taken place. I was called upon about eight years ago to examine the body of a woman, aged 26 years, who died in the Whitworth Hospital of an acute disease. This young woman had walked very lamely for many years, in consequence of her having had a most tedious and dangerous attack of hip- disease twenty years before her death, but after her recovery from the first attack she never had any pain or inflammation in the joint ; there were no evidences of suppuration ever having occurred ; marks of issues were on the nates. "When making an examination of the struc- tures around the articulation and of the joint itself, the muscles were found remarkably firm, but somewhat paler than usual ; the ligamentous structures around the junction of f These osseous vegetations we have already alluded to in this work, when speaking of the chro- nic strumous arthritis of the elbow : see p. 79, Elbow-joint, Abnormal Anatomy of. the femur with the os innominatum were very strong, and so close was the union of the bones that on a superficial view we might easily ima- gine that true bony anchylosis had occurred. 1 removed the bones, and they are preserved in the Richmond School Museum. The whole head of the femur has been absorbed, and only one-fourth part of the neck of the bone remains; the place of the cotyloid cavity is supplied by a rough scabrous surface, of an oval form trans- versely, and about one inch and one line in this its longest diameter ; the two rough bony sur- faces with eminences and depressions con- fronted to each, and reciprocally adapted, were joined by a species of strong fibrous capsule ; no motion whatever existed between these bones, yet when the ligamentous connexion between them was cut, it was evident that no bony union had taken place. In this case the false anchylosis had occurred in a very unfa- vourable direction ; the thigh was flexed to so great a degree that the knee was really elevated above the level of the hip-joint, and so much adducted at the same time, that the knee crossed much the middle line. When she stood up straight on the right and perfect limb, the left heel did not approach within twelve inches of the ground : the texture of the bones was as hard as iron. We find in a modern author the observation, which must be admitted to be correct, that true bony anchylosis of the hip-joint is rare; but, he adds, that many pathologists doubt that such an occurrence ever takes place : that the many specimens of true bony anchylosis of the hip we have witnessed, were all examples of union of bony surfaces in scrofulous cases, we would not wish to maintain, but we imagine many of them must have been the result of the ordinary hip disease cured, as it is called, by anchylosis. Sir Philip Crampton has shewn me a very fine specimen of anchylosis of the hip-joint, which very much resembles the pre- paration represented (fig. 312); the acetabu- lum had been the principal seat of the disease; it was much widened, and the head of the bone was drawn towards its upper and outer part, where firm anchylosis had taken place. In this case Sir P. Crampton assured me the pa- tient had a constitution eminently scrofulous. He got well of the hip-disease by anchylosis, the thigh-bone having been judiciously pre- served in a vertical direction during the pro- gress of the cure. He walked afterwards tole- rably well, but at the age of 26 became at- tacked with phthisis, and died. This case proves that true bony anchylosis can occur in the scrofulous subject, and that attention may occasionally overcome the disposition to exces- sive flexion and adduction of the limb. The museum of the Richmond Hospital contains three specimens, in which the junction of the os innominatum with the femur is as solid as if they formed but one bone, and a vertical section through the united bones shews as free a communication of the cells of the cervix femoris and those of the os innominatum as if these bones had never been separately formed. These seem to have been examples ABNORMAL CONDITIONS OF THE HIP-JOINT. 797 of early affections of the hip-disease, in which little or no displacement of the head of the femur occurred. The acetabulum, we know, is generally widened in this disease, and the head of the femur is drawn upwards and outwaids ; if at this period the inflammation be arrested, true bony anchylosis may occur ; and if a happy direction can be given to the shaft of the femur, a very useful limb may remain, even though the hip-joint itself has lost all motion ; the sacro-lumbar joint and the neighbouring inter- vertebral structures admit of much freedom of motion. In examining anatomically the hip-joints of those who, having had the chronic scrofulous disease of this articulation in their youth, and have recovered and lived for years, though lame, in these, instead of anchylosis, we find a false joint is formed. Of this imperfect cure of hip disease we have seen some examples, and we possess one remarkable specimen of it. In this the acetabulum was altogether removed, and a triangular space, encircled by a rounded brim covered with a compact stratum of bone, existed. The removal of the neck of the femur was so complete that a plane or rather concave surface corresponded to the inner side of the trochanter major, from which the neck of the bone naturally arises. It has been stated that luxation on the dor- sum of the ilium sometimes happens as a con- sequence of chronic disease of the joint; some- times the disease which carried away, in this instance, the borders of the acetabulum, seems, as it were, to have been transferred to the new surface of the os innominatum with which the head of the femur came in contact, and we find the process of ulceration has even continued its course ; again it sometimes happens that an- chylosis or a false joint has been formed. Albers and Rust have described the change which the bones of the pelvis undergo in their form and situation. The pelvis, in those who have for a long time gone lame, is pushed up- wards, and the sacrum is flat and straight. In a few cases, however, it is more curved than in the natural state ; the coccyx is bent strongly forwards, and the connexion of the last lumbar vertebra with the sacrum forms a right angle ; the ilium of the affected side stands higher, and has in general a perpendicular direction, and more of a triangular form ; the external surface is smooth, whilst the iliac fossa appears more hollowed than usual ; this hollowing probably depends on the action of the iliacus intern us, which is greater than that of the gluta;i. The horizontal ramus of the pubes often seems lengthened and lower than in the natural state, and the ischium is usually drawn outwards and forwards ; the perpendicular direction of the foramen ovale is changed more to a hori- zontal one, and the opening assumes more of a triangular form, its base being turned towards the acetabulum. In consequence of the changed situation of the bones of the pelvis, its different diameters undergo an essential devia- tion from the natural state, the superior aper- tures of the pelvis are commonly somewhat oblique, and the pelvis is broader on the affected side from before backwards.* The muscles in advanced cases are in a state of atrophy, of a greenish hue, and often matted together; sometimes they form the walls of scrofulous symptomatic abscesses, containing a thin serous pus mixed with flakes ; sometimes the pus is inodorous, of ordinary character. Usually the contents of the abscess make their way to the skin, more rarely to the mucous surfaces. In more advanced cases these ab- scesses are found to contain fetid air and puru- lent matter of a very bad quality ; in these latter circumstances we discover either an ex- ternal or internal fistulous opening ; the walls of the abscesses have collapsed, and have been converted into fistulous canals lined by false membranes ; these have become, as it were, the excretory canals, through which the matter has been discharged from the interior of the dis- eased joint, and through which sabulous mat- ter, small hard pieces of bone, or pieces as large as the epiphysis of the head of the femur, as elsewhere noticed, have made their way. The abscesses are found, on dissection of those who have died of morbus coxae strumosa?, pointing or to have opened in various directions. We have already stated that the capsular ligament has been found perforated by fistulous openings, and that in the advanced stage of the disease little or no vestige of the capsule is left. The abscesses, therefore, we meet with on dis- section may be considered as reservoirs for the matter which proceeds from the carious bones ; occasionally, no doubt, we shall find around the joint abscesses which have no communica- tion whatever with the diseased articulation : not only in the soft parts around the joint have we met with such isolated collections of matter, but also in the body of the os ilii, and in the centre of the trochanter major of the femur. We have given an account of an acute case of morbus coxae, in which a psoas abscess was found to have originated in a carious hip-joint. The communication of the carious bones with the interior of the sheath of the psoas took place through a small perforation in the hori- zontal ramus of the os innominatum. In this case also an abscess existed in the true pelvis, and death was the consequence of it, having burst into the vena cava. In Mr. Liston's collection there is a specimen shewing ex- tensive destruction of the acetabulum, head and neck of the femur, with several sinuses leading from the joint, and one in particular of large size, leading towards the rectum through the foramen ovale ; there is also the rectum corresponding to this preparation, with a rounded opening sufficient to admit the point of the little finger, about an inch and a half above the anus. In this case the abscess lay across the pelvis; by one of its extremities it communicated with the diseased hip-joint through the foramen ovale and ulcerated cap- sular ligament, and by its posterior extremity with the rectum. The case of pelvic abscess I have so often adverted to was very similarly * Coulson, p. 42. 798 ABNORMAL CONDITIONS OF THE HIP-JOINT. situated, but instead of opening by its posterior extremity into the rectum, its fundus was ele- vated somewhat higher in the pelvis, and burst into the vena cava. The late Dr. M'Dowel, in the fourth volume of the Dublin Journal, says that in two cases of hip-joint disease he had seen several years since, the matter had passed into the pelvis through the bottom of the acetabu- lum, and there accumulated in such quantity as to compress the bladder and cause retention of urine, requiring the daily use of the catheter. He also adds, that this route for the matter is not uncommon, and in its progress that it may form a tumour of considerable size by the side of the rectum, and occasionally burst into the cavity of this intestine. Sir A. Cooper men- tions the latter occurrence in one instance. Dr. M'Dowel adds, I had an opportunity of wit- nessing it. Abscesses take their course from the diseased joint into the pelvis, and open into the vagina. Sir B. Brodie mentions a case of this kind in a child aged 11 years; and in Dr. Kirby's collection, which he presented to the College of Surgeons, is a similar ex- ample. Dr. M'Dowel, in the paper already alluded to, observes that he is not aware of its being recorded that an iliac abscess may result from a caries of the hip-joint, yet in four cases, he adds, I have found it to occur. The fluid escaping through an opening on the inside of the capsular ligament, passes upwards behind the psoas and ascends into the iliac fossa, de- taching the muscles from the bone. In such cases we have considerable fulness in the groin, which can be traced upwards behind Poupart's ligament ; from the stretching of the filaments of the anterior crural nerve more neuralgic pain attends this case than we usually find in disease of the hip-joint. The iliac vessels are dis- placed, become flattened and adherent to the sac ; from the compression of the vein much more oedema of the limb is present than in or- dinary eases. The ccecum or the sigmoid flex- ure of the colon may be considerably displaced or united to the sac* Sometimes it passes behind the vessels, and accumulating, it may compress the bladder and rectum, which then form the inner wall of the abscess. In a very interesting case of iliac abscess which was treated in the year 1833 in the Rich- mond Hospital, ulceration of a portion of the ilium adhering to the wall of the abscess oc- curred, and its contents, after being poured into the abscess, escaped externally through a fistu- lous opening near the spine of the ilium ; ulce- ration also of the external iliac artery took place about an inch and a half above Poupart's liga- ment, and sudden death resulted from the blood escaping in large quantity into the cavity of the abscess. The preparation is preserved in the museum of the Richmond Hospital. The anterior and crural nerves are often found on the stretch. We have already mentioned a case of this kind, (Clarke,) and Sir B. Brodie mentions one in which he found two enlarged * The matter, which is generally prevented from passing down into the true pelvis by the connexion of the fascia iliaca, sometimes makes its way into this cavity by ulceration of this fascia. lymphatic glands, each the size of a walnut, immediately below the crural arch in the fore part of the joint, and these lay in contact with and immediately behind two branches of the nerves, so as to keep the latter on the stretch, like the strings passing over the bridge of a violin. We must not forget that the diseased action in these cases of chronic strumous arthritis is not confined to the joint. We have seen ex- amples in the living and specimens in mu- seums, proving that at the same lime both hip- joints may be engaged in the same individual. In acute cases we have given an example of the membranes of the brain having been affected, so also in chronic cases; tubercles have also been found in the lungs, the mesenteric glands extensively enlarged, and ulcers in the intes- tines, and tubercular accretions in the perito- neum. 3. Chronic rheumatism. — (Morbus coxce senilis, or chronic rheumatic arthritis of the hip.) By these terms we would wish to de- signate a very peculiar disease of the hip- joint, the morbid results of which are now pretty well known to pathological anatomists ; but it must be confessed that very little has been done to make the profession acquainted with its symptoms or appropriate treatment. History of the disease. — We will venture to assert that there cannot be a more graphic il- lustration given of this disease and its conse- quences than those to be found in the Museum Anatomicum of Sandifort, who has not confined his delineations to the head and neck of the thigh-bone, but has also shewn the various alterations of form which the acetabulum un- dergoes.* For many years this disease has been accurately described in the clinical lec- tures delivered in the different hospitals in Dublin, and the importance of distinguishing it from the other affections of this articulation has been pointed out. Mr. Benjamin Bell, in his work on the bones, has, under the head of " interstitial absorption of the neck of the thigh-bone," alluded to this disease,and detailed many of its external signs, as well as the mor- bid changes which the neck of the bone suffers ; and in the sixth volume of the Dublin Journal, Mr. Smith, in a paper on the diagnosis of in- juries of the hip, has given a very good and concise account of this remarkable affection of the hip-joint. The writer of this article long ago, in his lectures, gave the name of morbus coxa seni- lis to the disease in question, but as he has since met with many instances of it occurring so early as at the age of thirty or forty, he is now disposed to substitute for this name that of chronic rheumatic arthritis of the hip-joint, and he considers it as the same disease pre- cisely as he has elsewhere in this work described as affecting other articulations. (See Elbow, Hand, Knee, Shoulder.) As to the cause of this chronic disease of the hip-joint, we believe little is known. We have heard it frequently attributed to the effects of cold and wet ; and an acute attack of rheu- * Mus Anatom. Lugduui Batavorum, 1793. vol. ii. tab. lxix. ad lxxiii. ABNORMAL CONDITIONS OF THE HIP-JOINT. 799 matic arthritis of the hip-joint produced by cold, we can easily conceive may occasionally merge into the chronic affection we wish to describe. We have also reason to think that falls upon the great trochanter have given rise to the first symptoms of this disease ; but in many cases no satisfactory cause can be assigned by the patient for the origin of the affection. Symptoms, 4'C- — The patient complains of stiffness in the hip-joint and about the great trochanter; also of a dull boring pain which extends down the front of the thigh to the knee. The stiffness is most felt in the morning when the patient commences to walk ; but after exercise the movements of the joint be- come somewhat more free. In the evening of a day the patient has had much walking exercise, the pain is always more severe. The uneasiness, however, gradually subsides after he has retired to bed. The pain is always in- creased when the patient throws the weight of his body fully on the affected joint. But let the surgeon press on the great trochanter, or adopt any other expedient so as to push the head of the bone even rudely against the ace- tabulum, and these manoeuvres are the sources of no uneasiness whatever to the patient. Al- though we can easily satisfy ourselves that no actual anchylosis exists, still it is evident enough that the motion of rotation is lost, and that the other movements, particularly flexion, are confined within very narrow limits. When we place the patient in a horizontal position, and endeavour to communicate any of these movements to the hip-joint, the patient com- plains of pain, and an evident crepitation can be heard and felt deep in the articulation. The limb is apparently shortened by from two to three inches ; the apparent shortening arises from the obliquity of position of the pelvis relatively to the spine, and the elevation of the affected side is such that the crest of the ilium and the last short rib approach nearer to each other at this side in the ordinary attitude of standing by two inches than those of the opposite side. All these circumstances account for the apparent shortening of the limb, which however, on accurate measurement, will be found not to be really shortened more than an inch. The patient walks very lame, and with the foot and whole limb greatly everted. The nates of the sound side is unusually prominent, while that of the affected side is quite flat, and no trace of the lower fold of the glutauis is seen. The mus- cles of the thigh also seem somewhat atrophied, still they do not want for firmness ; and we may uniformly observe that the calf of the leg of the affected limb is not inferior in size and firmness to the other. When we minutely examine the great trochanter, we find it larger and more prominent than usual ; and about the situation of the acetabulum, horizontal branch of the os pubis, and lesser trochanter, bony pro- tuberances can, upon careful examination, be recognized. This disease, when once fully esta- blished in the hip-joint, rarely or never extends itself to the other articulations. We have known, however, a few examples in which it affected both hip-joints in the same individual. The chronic inflammation of the various struc- tures of the joint in which the disease consists, is never accompanied by any appreciable de- gree of heat or external swelling of the soft parts, and we have never heard of the inflam- mation going on to suppuration. The following case will shew the necessity of making the profession fully acquainted with this disease, as it proves how very obscure are the early signs of the affection, and that even the morbid appearances may be confounded with those which are the result of accident. At the meeting of the British Association in Dublin, in the year 1836, one of its most dis- tinguished members, Mr. Snow Harris of Ply- mouth, made the following communication to the medical section : — " Sir A. Cooper and many other eminent surgeons had doubted the possibility of union taking place in fracture of the neck of the thigh-bone, within the capsular ligament. A case had lately fallen under his (Mr. H.'s) notice, which he thought would tend to set the question at rest. It was that of a gentleman who had received an injury by being thrown from his gig ten years ago. He had got up and walked immediately after the accident, but continued lame from that period up to the time of his death. He had been at- tended by some of the most celebrated surgeons in London, but they had not been able to de- termine whether there was a fracture of the bone or not, but kept him lying on a sofa for nearly twelve months. The injured limb was shortened, the foot everted, the thigh wasted, and owing to the constant inclination of the body forward on one side, a lateral curvature of the spine took place. Some time ago the gentleman died of disease of the heart; and Mr. Harris, being anxious to examine the parts, removed the acetabulum and a portion of the thigh-bone, which he then presented for the inspection of the meeting. He had found the trochanter higher up than natural, and the neck of the bone shortened ; a section of the bone had been made, and the line of union, in Mr. Harris's opinion, was clearly manifest." * When Mr. Harris exhibited this specimen to the medical section of the British Association which met in Dublin, it excited much interest, first as the individual, the subject of the case, was the celebrated comedian Mr. Matthews, and secondly, as at the announcement of the case it was asserted that it settled in the affirmative the much agitated question, whether the intra- capsular fracture of the cervix femoris was or was not susceptible of osseous union. The writer was present at the communication of this case to the section, and upon the presentation of the specimen expressed his doubts that this case, either from its history or post-mortem appearances, was an example of the intra-cap- sular fracture, and rather held the opinion that it was one of this chronic rheumatic affection which he has been endeavouring to describe ; in which opinion he was most decidedly con- finned upon inspecting the acetabulum, the widening of this cavity, the complete filling up * Sec Dublin Journal, vol. viii. 800 ABNORMAL CONDITIONS OF THE HIP-JOINT. of the fossa which is normally destined to con- tain the substance called Haversian gland, the shortening of the neck of the femur and depres- sion of the head towards the lesser trochanter, and the ivory deposition on it. In this view Mr. Smith, who had so well described the disease in question, and the hospital surgeons around him, concurred, and Mr. Snow Harris himself quickly became a convert to our views, and we are sa- tisfied from what we observed of his liberality, that we have his full permission to communicate this case in its present form to the profession. The sketch (fig. 315) is taken from the cast of the Fig. 315. Mr. Snow Harris's case. head and neck of the femur presented by Mr. Harris to the College of Surgeons, Dublin. The upper part of the head of the femur was exceed- ingly rough on its surface, and of an oval form from above downwards ; the axis of the neck was at right angles with the shaft, and seemed lo run horizontally inwards and backwards, so that the length of the fossa which exists poste- riorly between the corona of the head and the posterior inter-trochanteric line, was in this case less than a quarter of an inch, a fossa which we know naturally measures two inches. In viewing the oval form of the head, we conclude the movement of rotation must have been im- possible ; from the shortening of the neck pos- teriorly, we can infer that the toe and foot must have been greatly everted, and from the depres- sion of the head, to the level of the trochanter, the femur must have been nearly one inch shorter than the other. The lamented indivi- dual had not suffered from the disease more than ten years, so that the morbid appearances were not to the same amount as we are accus- tomed to see as the result of this very slow dis- ease. The following case is that of an individual who has been, to the writer's knowledge, suffer- ing for many years under this disease. Patrick Macken, now- aged seventy-seven years, was brought up as a postilion and groom, but for the last seventeen years has been quite unfit for service in consequence of his having been afflicted with a very severe pain in his right hip ; from the first attack of which he be- came lame, and ever since the lameness has been slowly but gradually increasing. In every Fig. 316. Chronic rheumatic arthritis of tlie Hip. other respect his health is excellent, except that he has some wandering rheumatic pains in other joints, particularly in the right shoulder. Hewalkswith great labour and pain, and now requires the assistance of a stick in each hand (Jig. 316); in the morning his movements are stiff and confined, but they become freer on exercise; in the evening of a day he has walked much, the pain and stiffness are worse and increased in propor- tion to the excess of exercise and labour he had undergone in the day. While he remains in bed he rests on the affected hip, and suffers no pain whatever except he suddenly turns himself in- cautiously. As soon as he gets up and throws his entire weight on the diseased hip-joint, the pain commences; if asked in what particular part of the joint he feels most suffering, he points to the back part of the great trochanter and to a point which corresponds to the situation of the lesser trochanter ; he says the pain shoots from these points down the front of the thigh to the knee. These pains are sometimes more severe, and sometimes less, without his being able to as- sign any cause for these alterations, and he can- not observe that the state of the weather has any influence on them whatever. As he stands at rest, he throws the weight of his body on the left or unaffected limb, ABNORMAL CONDITIONS OF THE HIP-JOINT. 801 while the right leg hangs in front and slightly across the left, and seems to be at least three inches shorter; he leans slightly back and supports himself on two sticks : as he walks the right foot is considerably everted, and when he moves without sticks (which he accomplishes with the greatest difficulty) he places the whole sole of the foot flat upon the ground. He never, however, ventures of his own accord to move without the help of two sticks, by the assist- ance of which he is enabled to walk quicker; while moving along thus, the heel of the affected limb does not quite reach the ground, and the lumbar vertebrae undergo great motion. He cannot under any circumstances flex the thigh on the abdomen, so that when he assumes the sitting posture, he is obliged to place him- self forwards on the very edge of the seat, the right thigh remaining in the same line as the axis of the trunk, the leg usually flexed and placed under the chair, or across behind the other, and he finds the utmost difficulty in putting on his stockings and shoes. He has scarcely any motion in the hip-joint. When we view the hip in front, and examine it, we see and can feel a considerable bony fulness, corresponding to the horizontal branch of the pubis : the trochanter major seems placed very high up, and is extraordinarily large as if sur- rounded with ossific deposits. The thigh is somewhat atrophied, being an inch and a half less in circumference than the other, but the calf of the leg is not reduced, and the muscles seem firm ; the apparent shortening of the limb, when he rests on the sound one, arises from the lumbar vertebra being much curved to the oppo- site side, and the pelvis being elevated on the affected side, while the real shortening ascer- tained by accurate measurement amounts only to half an inch. If we place the patient horizontally and attempt to communicate to the hip-joint any movement, as of rotation, flexion, abduction, a well-marked crepitus is elicited, and the range of motion is found to be very limited indeed; a little abduction is admitted ; rotation and flexion seem just to a sufficient degree to shew that no anchylosis exists. The move- ments give some pain to the patient, but we can press the trochanter firmly so as to direct the head of the bone deep against the fundus of the acetabulum, and we can even strike the heel and sole of the foot with violence without giving the patient the slightest sensation of pain. The anatomical characters of this disease are very well marked. The muscles are usually of a paler colour than natural, and are found not to be so well developed ' as those of the opposite or sound hip. The fibrous capsule of the joint is greatly thickened, the cotyloid ligament is either ossified or absorbed, and the ligament which completes the notch, and in the natural state gives origin to the liga- mentum teres, is usually converted into bone, leaving generally beneath its arch whether bony or not a space for the transmission of bloodvessels to the interior of the joint;* when * Cruveilhicr, livraison iv. p. L La presence VOL. II. the disease is fully established the ligamentum teres is altogether removed, the synovial fluid is deficient in quantity, and the cartilage is removed from the bottom of the acetabulum, and upper surface of the head of the femur. If here and there some vestige of the synovial membrane or sub-synovial tissue remain, it is in a highly vascular condition, presenting an intensely red colour. In a case of dissection which Messrs. Smith, Brabazon, and the writer witnessed lately of this disease, we observed that the shortened neck of the femur was entirely surrounded with a number of red villous - looking productions of the synovial membrane. These were of a rounded and conical form, half, an inch long and two or three lines broad at their bases. They resem- bled much in form the long conical papillae to be seen on the tongue and about the fauces of herbivorous quadrupeds ; however, instead of being white and firm they were soft and villous, and of an intensely red colour. The line of the corona of the head was absorbed and excavated in points, and the different foveas or depressions were completely occupied by these vascular fimbriae. Still more recently the wri- ter met with a similar specimen which he pre- sented for inspection to the Pathological So- ciety, in which these vascular fimbriae were equally conspicuous.* The acetabulum is generally much larger and deeper than natural, and forms a circular cup often two inches deep with a complete level brim, which is sometimes so much narrowed as to render the extraction of the head of the femurdifficult. This is the most frequent abnor- mal appearance the acetabulum presents ; but occasionally it is increased in size, and is at the same time very shallow and of an oval form. When we examine the bottom of the acetabu- lum we find it widened and not any trace of Haversian gland is left ; the interior presents a worn and porous appearance, the cartilage and compact stratum of bone which the caitilage normally covers, having been removed, and in some places where the friction and pressure from the head of the femur have been greatest, instead of a rough and worn porous appearance, resulting from the exposure of the cells of the bone, a dense enamel has been as it were ground into these pores, and here the surface presents the polish, smoothness, and hardness of ivory. This mechanical removal of the carti- lage and exposure of the interior of the cells of the bone, and substitution for the cartilage of a dense inanimate enamel, we imagine, are pro- cesses which are not confined to the acetabu- lum ; but their results are seen also on those parts of the head of the femur which are sub- jected to pressure and friction ; hence we find the effects of friction, above alluded to, most d'un nerf et d'un vaisseau, cespartiesfondamentales de l'organisation, semblent en quclque sorte re- spectees par les lesions organiqucs, qu'elles soient ces lesions circulent tout a lit our, mais ne les en- vahissent presque jamais, oil du moins les envahis- sent apres tous les autres tissues lorsquellcs sont parvenus a leur dernie.re periode. * Dublin Journal for March 1839, No. xliii. 3 G 802 ABNORMAL CONDITIONS OF THE HIP-JOINT. upon the upper surface of its head which supports the acetabulum in standing and pro- gression. The form of the head of the bone becomes changed and flattened from above downwards ; something like a bending or yielding of the neck of the bone may now be observed, and sometimes the inferior part of the circumference of the head of the femur is so mucl) depressed that the under surface of the head has approached to the lesser trochanter. Fig. 317. Upon a cursory examination, it looks as if the " head of the bone were forced downwards by the action of some great pressure from above, and cases have occurred in which at last the head of the femur seemed to have sunk even below the level of the great trochanter, and to be supported by the lesser." ( B. Bell.) But besides these which we attribute to the effects of physical causes, there is, in the con- templation of the morbid results of this chronic disease of the hip-joint, sufficient to satisfy us that a very active vital process is going on in the interior of the bones, as well as in all the structures around the diseased joint. The Ihickening of the fibrous capsule, and hyper- amic state of the synovial structures, the exu- berant growth of bone which we see around deepening the acetabulum, or surrounding its brim with bony nodules; the enlargement of the head of the femur, so as to make this head assume an oval convex surface, measuring in circumference ten inches and a half, as in the specimen from which the drawing (Jig. 317) was taken, all these are sufficient proofs that besides the inlerstitial absorption going on in the interior of the cervix femoris in these cases, a very active condition of the minute arteries exists externally, giving birth to those exostotic deposits which encircle the head and inter- trochanteric lines of the femur. It has been remarked, and we think with much truth, that those specimens which have been frequently produced and mistaken for united fracture of the neck of the femur, have been examples of interstitial absorption of the neck of this bone combined with external exostotic deposits; but these mistakes, however, we trust are not here- after likely to occur. Section 111. Accident. — The hip-joint is, of course, like the other articulations, liable to sprains and to contusions. These do not re- quire any special notice here; but fractures and luxations of the bones of this important articulation demand from us full consideration. I. Fractures. — Fractures of the os innomi- natum may traverse the bottom or fundus of the acetabulum, or some portion of the brim of this articular cavity may have been broken off. 1. Fracture of the acetabulum. A. Fracture of its fundus. — When fracture of the bones of the pelvis happens to traverse the bottom of the acetabulum, the prognosis is unfavourable, as it is in all cases of fracture of the bones of the pelvis. When this fracture through the fundus of the acetabulum is the consequence of a fall on the feet, knees, or trochanter major of the femur, it sometimes happens that the head and neck of the femur unbroken are driven into the cavity of the pelvis. " Nous avons observe," says Dupuytren, " plusieurs fois, l'enfonce- ment de la cavite cotyloide par la pression exercee par la tete du femur, a la suite d'une chute surle pied ou lesgenoux." In this case, the head of the femur is driven with force against the fundus of the acetabulum, and the latter breaks, and is crushed in, " enfonce." The most remarkable case observed by Dupuytren was the following : — " The bottom of the cotyloid cavity had been driven in, and the head of the femur had passed entirely into the pelvis. The neck, which had not suffered any solution of continuity, was so strongly engaged in the opening, that, even when making the anatomi- cal examination, I found it very difficult to disengage it, and to reduce this new species of luxation."* As these important remarks of Dupuytren are not accompanied by all the detail that is to be desired, where novel obser- vations are reported, we shall here adduce the following case of fracture of the fundus of the acetabulum, with displacement of the head of the femur into the pelvis. Death occurred on the fortieth day after the injury, from diffuse inflammation. An opportunity was afforded to us of investigating anatomically the precise na- ture of the lesions in this case. On the 3rd of December, 1834, a man, named William Sherlock, set. 26, a painter by trade, was admitted into Jervis-street Hospital, under the care of the late Mr. Wallace. A few minutes before his admission, this poor man had fallen from a ladder, from a height reported to be fifty feet, on the flags of the street. On the next day, the 4th of December, when he had recovered from the insensibility and collapse which had succeeded to the fall, we found him complaining of intense pain of the right hip. He was quite unable to move the right thigh, and would not permit any exa- mination of the hip, as the slightest movement communicated to the limb produced intense agony. The integuments covering the tro- chanter were discoloured, and there was much swelling around the hip-joint. The right or injured extremity was two inches shorter than the left, which circumstance he attributed to a * Lemons Orales. ABNORMAL CONDITIONS OF THE HIP-JOINT. 803 fracture of the femur, which had occurred some years previously- Besides this severe injury of the hip, it was also manifest, from some dyspnoea, cough, and bloody expectoration, that his chest was also injured, but venesection and other suitable treatment having been resorted to, the affection of the chest seemed to subside. His cough and dyspnoea for a time had disap- peared, and his pulse fell to 80. On the twenty- third day from the accident, he said he felt that he had caught a most severeand violent cold, from a window having been kept open over his head. On this (23rd) morning, I found him suffering from great difficulty of breathing and violent fits of coughing, accompanied by scanty frothy expectoration. His pulse was 110, and hard, his tongue was brown and dry, his skin was hot, and I learned that these symptoms had suc- ceeded to a rigor. They were attributed by me to pneumonia with acute pleuritis and consi- derable effusion, of which there were found, on examination of the chest by auscultation and percussion, very evident signs. These were actively combated by the ordinary treatment, but without success. His pulse was generally 120. He had cough, with muco-purulent ex- pectoration, and dyspnoea. He slill obstinately refused to permit any accurate examination of the limb to be made. He said his right thigh was now as powerless as at first, but the injury did not prevent him sitting up in bed, when, from the urgency of the dyspnoea, he felt the desire for this position ; on one occasion he had himself taken up, and placed for a time sitting up in a chair. On the thirty-third day after his admission, I found that his right leg and thigh had swollen, that he had raved much during the night; and that he had alternate flushings and paleness of countenance, which betrayed much distress. He now complained of pain in the right shoulder. His pulse was 130, small and compressible. He had reten- tion of urine. His temper was irritable; his tongue was red, and morbidly clean and dry. He had much thirst. His lips were pale and bloodless. He died on the 12th January, the fortieth day from the accident. Post-mortem examination. — There was effu- sion of pus into the cavity of the right pleura, and the usual results of acute pleuritis ; pus also in the cavity of the pericardium, and a thin reticulated layer of lymph on the surface of the heart. An incision made through the soft parts to expose the bones of the hip-joint gave exit to a large quantity of dark brown serum, mixed with pus. This collection of matter extended from the superior part of the thigh, under the peritoneum up to the kidney. The soft parts having been removed, and the bones exposed, it was found that the shaft, head, and neck of the femur were uninjured, but the head of the bone was driven through the fundus of the acetabulum, which was fractured in a stellated manner, having been divided into three por- tions. The spiculated edges of the cavity pro- truded into the pelvis to the extent of one inch. They were sharp and hard. Nature had not made the slightest attempt at reparation. The finger could be passed along the neck of the thigh-bone into the cavity of the pelvis, through the perforation in the bottom of the acetabulum. The pelvis had been broken in several places. There was a comminuted fracture of the horizontal ramus of the pubis near its crest. There was another fracture of this ramus at its junction with the ilium, and a fracture through the body of the os innpmi- natum extended from the anterior inferior spi- nous process to the great sciatic notch. B. Fracture of the brim of the acetabulum. ■ — -The superior and back part of the cotyloid cavity, which overhangs the head of the femur, which is called by Soemmering the supercilium, is sometimes broken off, and it follows almost as a necessary consequence, that a dislocation upwards and backwards of the head of the femur shall occur. It is an accident most liable to be mistaken, and most difficult to manage. We believe, indeed, in all the cases which have occurred, that permanent lameness has been the result. In such cases, the luxation of the hip is reduced without much difficulty, but dis- placement again shortly recurs. In symptoms and effects the case has a strong resemblance to the congenital luxation of the femur. I was once invited by my friend, Mr. Hilles, (now of London,) to see a case of supposed dislocation upwards and backwards on the dorsum of the ilium. I met the late Dr. M' Dowel in con- sultation on the case. It was as follows : — Thomas Venables, set. 25, on the 4th of Oc- tober, 1834, received a severe injury of the right hip-joint in leaping across a ditch, having alighted with force upon the right leg. He fell immediately, and was unable to rise from the ground, or to walk or stand when raised. When the patient was supported in the erect posture, he had the ordinary symptoms of dis- location of the thigh-bone upwards and back- wards on the dorsum of the ilium. No cre- pitus was discovered. On the following morning an extending force having been ap- plied by the pulleys, the head of the bone resumed its natural situation, and the deformity of the limb disappeared. When the patient was visited on the following morning, (the 6th,) it was found that during the night the head of the bone had started from the acetabulum, and that all the former signs of the injury had re- appeared. On the 7th, the displacement was again reduced. While the bone was yielding to the force of the pulleys, the writer had the palm of his hand pressing on the great tro- chanter, as this last advanced slowly towards the acetabulum. He was sensible of a rough grating sensation, which was communicated to his hand, and gave him the idea as if the head of the bone were dragged along a scabrous rough surface. The case proceeded favourably until the night of the 10th, when, owing to the dis- turbance occasioned by the action of a purga- tive medicine, the dislocation recurred a third time. It was observed that, although when the patient was supported out of bed the foot was inverted, still the toes could be somewhat everted. An accurate examination being now instituted to ascertain whether a fracture ex- isted, a distinct crepitus was discovered at the 3 c 2 804 ABNORMAL CONDITIONS OF THE HIP-JOINT. upper and back part of the acetabulum. The crepitus and frequent recurrence of the dis- placement rendered it sufficiently obvious that the brim of the acetabulum had been broken in the above-mentioned situation. The bone was a third time restored to its place, and a strong band placed around the pelvis. Inl83G, I admitted the man into the Richmond Hos- pital. He was at this time unable to walk without the assistance of a crutch. The in- jured limb was one inch and a half shorter than the other. When standing, he rested it upon the points of the toes, the heel being drawn upwards; but a slight degree of extension was sufficient to restore it to its natural length ; and when the man was lying in bed there was hardly any difference perceptible in the length of the two limbs. The breadth of the injured hip was occasionally greater than that of the sound one, and the head of the femur could be pushed upwards easily, and, of course, it al- ways ascended, when the patient endeavoured to support his weight upon it ; and in many motions of the joint, the rubbing together of the broken surfaces was distinctly audible. After having remained in the Richmond Hospital under our observation for two months, lie was discharged. Nothing could be devised to make his limb more useful to him. The fracture, therefore, of the supercilium of the ace- tabulum is a very serious injury, which it be- hoves surgeons to be well acquainted with. A successful mode of managing such cases has not yet been exemplified.* 2. Fracture of the superior extremity of the femur. — The head of the femur is so protected by the acetabulum, that it is seldom or never fractured, except by gunshot injuries. The neck and rest of its superior extremity are, however, we find, subjected to various accidents. The general symptoms of fractures of the neck and upper extremity of the femur are, that the affected limb is shorter than the other, the heel vises to the level of the opposite malleolus, the patella, leg, and foot seem much everted; there is a flattening of the natis, and a fulness of the groin. The patient does not attempt to stand, much less to walk. There is in the part itself, as ft were, a conscious inability to support the weight of the body, and even when the patient is lying on a horizontal plane, as in bed, we find that be cannot, by the unassisted effort of the muscles of the injured limb, elevate it from the horizontal level, upon which it lies power- less. When the surgeon, standing at the foot of the bed, seizes the affected limb, and pulls it towards him, so as gradually to overcome the contractile power of the muscles, the limb is restored to its natural length, and if now we resort to the painful expedient of rotating the thigh, crepitus is rendered manifest. When- ever the surgeon relaxes the force by which the limb was restored to its natural length, the shortening, eversion, and deformity of the limb * In the twelfth volume of the Dublin Medical Journal, Mr. R. Smith has made some valuable observations on this case, in relation to the diag- nosis of obscure cases of injury of the hip and shoulder-joints. recur. Such are the general signs of fracture of the upper extremity of the thigh-bone. The portion of the bone, called the neck, may be fractured transversely with respect to the direction of its long axis, either within or with- out the capsular ligament. The first is deno- minated the intracapsular fracture, the second the extra-cupsular fracture. Oblique fractures of the neck of the bone are not impossible. A. Intra-capsular fracture of the neck of the femur. — This fracture has been seldom seen in the young subject, but is one of the most common accidents to which elderly peo- ple are liable. In such persons many cir- cumstances in their organization appear to ac- count for their great liability to this accident. Their muscles have lost their firmness, and are more or less in a state of atrophy ; the trochan- ter major becomes peculiarly prominent; the neck of the femur yielding somewhat, perhaps, to the weight of the body, descends and loses some of its obliquity. This atrophy of the muscles and bones is not so frequently noticed in the male as in the elderly female, in whom the breadth of the pelvis is greater and the tro- chanter major more projecting. These obser- vations account sufficiently for the great liability to the intra-capsular fracture, which we notice in the elderly subject, and for the more fre- quent occurrence of the accident in the aged female than in the male. In the young subject the trochanter major does not project so much, the muscles surrounding the hip-joint are re- markably firm, and when falls on the side occur, the surrounding muscles and the os in- nominatuin share, with the great trochanter, the weight of the fall. The bone in the young subject is better calculated from its form and its organization to resist the effects of falls on the trochanter, and in these fractures of the neck of the femur have been rarely witnessed. In the young subject, too, the neck of the femur is comparatively shorter than in the aged, the angle of union of the neck with the shaft of the bone is more open, and the axes of both neck and shaft are more in a line. The great proportion of animal matter existing in the bones of the young, and consequent elasticity of the bone, render it capable of resisting frac- ture, while, on the contrary, the comparative deficiency of animal matter, and the consequent redundancy of earthy material in the aged sub- ject, render the neck of the femur friable. In a word, the tissue of the bones in general does not escape, in the aged, that atrophy which affects the rest of the system, and when we re- collect the functions which the neck of the thigh-bone has to perform, we shall not be sur- prised to learn that the effects of this atrophy are more readily felt and seen in this part of the osseous system than perhaps any other. The superincumbent weight of the body and the action of muscles must have a tendency to diminish the obliquity of the neck of the thigh- bone, to render it more horizontal, and conse- quently less capable of bearing up against the effects of concussion. Besides the loss of obliquity of the neck of the thigh-bone, we find two other circumstan- ABNORMAL CONDITIONS OF THE HIP-JOINT. 805 ces relative to the neck of the bone itself, ren- dering it very liable to fracture in the aged. I mean the expansion of the cells, by which the strength of the interior of the bone is dimi- nished ; and, secondly, by the partial removal by absorption of that long bony arch of com- pact tissue, upon which in the adult depends, vve believe, the principal strength of the neck of the bone (Jig. 318) ; and even in many aged subjects, vve find the partitions of the bony cells removed, and a large cavity filled with fatty medulla occupies the centre of the cervix femoi'is. All these alterations obviously weaken this portion of the thigh-bone, and vve feel very little doubt but that when the condition of the bone above alluded to exists, even without a fall a fracture may occur. We have noticed specimens of senile degeneration of the neck of the femur in museums, in which the neck of the femur had been removed gradually by ab- sorption, so that the head of the bone had ap- proximated to the trochanters. Such specimens, where the history of the case was unknown, have, vve doubt not, been from time to time adduced as evidences in favour of the possibi- lity of bony consolidation of the intra-capsular fracture. These observations on the effects of senile degeneration of the neck of the thigh- bone sufficiently account for the remarkable frequency of the intra-capsular fracture of the cervix fernoris in the aged subject from the most trivial causes. The fracture, under such circumstances, should, in our minds, be looked upon more as a stage of morbid alteration, from which no amendment is to be expected, than as an accidental lesion, which the efforts of nature and the aid of surgery can be deemed adequate to repair. B. Extra-capsular fracture of the neck, and fracture of the superior portion of the shaft the femur. — Fracture of the neck of the femur may occur in a part of the bone immedi- ately external to the synovial sac and capsu- lar ligament; it may pass obliquely through the cervix fernoris and trochanters, or it may occur in the cellular and spongy portion of the bone which is immediately external to these processes. In all these cases the accident is usually met with in young and vigorous indivi- duals, and is often very severe. There is in these cases much deformily, great eversion of the limb, with considerable shortening and swelling. The fracture having traversed the bone external to the capsular ligament, there is but little to resist the full force of muscular action upon the lower fragment of the bone, while the upper is forced downwards by the weight of the body, so that, from both these causes, much shortening is produced. The muscles are in a state of spasm, and at first resist the surgeon's efforts to bring down the limb to its normal length. The muscles gra- dually yield to gentle and continued extension, and if now a movement of rotation be commu- nicated to the broken femur, a crepitus can be felt by the hand pressing on the great trochan- ter, which on rotation of the femur is perceived to move in a small circle. Fversion of the whole limb, in cases of fracture of the upper extremity of the femur, has been noticed as one of its most prominent symptoms, and the cause of it may be fairly attributed to the pre- ponderating influence of the rotators outwards, to which the lower fragment is abandoned when fracture has occurred : the rotators out- wards are the glutaeus maximus, the three ad- ductors, the pectinalis, the psoas magnus, and iliacus internus, together with the obturators, pyriformis, and other muscles, inserted into the posterior inter-trochanteric line. These mus- cles are solely opposed by the rotators inwards, which are few and comparatively weak. Not- withstanding the violence of the injury in ge- neral, and the deformity, the prognosis in these cases is much more favourable than in the case of the intra-capsular fracture, because in the former a solid bony union of the fragments may be reasonably hoped for. In considering the symptoms of fracture of the superior extremity of the shaft and of the neck of the femur, whether the seat of fracture be within or without the synovial cap- sule, it should be recollected that extraordi- nary cases may occur; thus there may be fracture combined with inversion of the limb. The cause of this inversion, in particular cases, has been sought for, and Mr. Guthrie gives ingenious anatomical reasons for this rare symp- tom, depending upon the line of direction the fracture may have taken ; if, for example, the fracture may have taken such a course as to detach from the shaft of the femur the neck, and at the same time also the lesser trochanter, to which is attached the great rotator outwards, the psoas and iliacus, and if at the same time the attachments of the gemini, obturators, and pyriformis be destroyed, in this case Mr. Guthrie supposes that there is an anatomical reason for the rotation inwards, as the tensor vaginas ferno- ris and the anterior fibres of the glutaeus me- dius remain unopposed. This explanation is ingenious, but the cause of occasional inversion of the limb in fracture, noticed by Petit, De- sault,and all subsequent writers, has not yet, in our mind, been sufficiently elucidated. The phenomenon of inversion of the foot, in cases of fracture of the upper extremity of the femur, is extremely rare, but it has been noticed in the intra-capsular fracture, (Stanley, Smith,) in the extra-capsular fracture, (Guthrie,) and we have ourselves seen it in all these cases. The deviation inwards, says Dupuytren, is so rare, that we can scarcely reckon upon meeting it once in a hundred cases. The surgeon of the Hotel Dieu attributes much of the rotation out- wards in fractures of the neck of the thigh-bone to the action of the adductor muscles, but adds, " il faut dire aussi, qu'on notice presqueaucune partie d'une autre cause, qui cependant peut seule rendre compte de la deviation en dedans, et apprendre a y remedier. Je veux parler de I'obliquite des fragmens dans la fracture du col du femur, si le fragment interne se porte en arricre, et l'externe en avant, il y a alors devia- tion en dehors. Si, au contiaire, la fracture est oblique, en sens inverse, la deviation aura lieu en dedans. C'est done par I'obliquite des frag- mens, que ces varietts de deviation peuvent ctre appreciees." C. Fracture of the neck of the femur, compli- 806 ABNORMAL CONDITIONS OF THE HIP-JOINT. cated with fracture through the trochanter major. — In the thirteenth volume of the Medico- Chirurgical Transactions, Mr. Stanley has re- marked that among the more complicated inju- ries to which the hip-joint is liable, that of fracture of the trochanter major, combined with fracture of the neck of the femur, has, under certain circumstances, a strong resemblance to dislocation of this bone. Whenever the frac- tured portions of the trochanter can be brought into contact, a crepitus will be perceived, which will enable the surgeon to ascertain the precise nature of the injury ; but when from the direc- tion of the fracture, one portion of the trochan- ter major has been drawn by the muscles to- wards the sciatic notch, no crepitus can then be discovered. A direct source of- mistake will then arise from the positive resemblance of the fractured portion of the trochanter to the head of the femur, the former occupying the place which the latter would do in dislocation, and if, with these circumstances, there should hap- pen to be inversion of the injured limb, the difficulty of diagnosis must be considerably in- creased. The writer has seen such cases as those alluded to by Mr. Stanley, and when he confined his observations to the consideration of the joint only, he felt all the difficulty alluded to in forming an opinion ; but in these cases the limb can in general be brought down to its natural length by forcible extension, and it is possible, too, to flex the thigh on the abdomen, which we know to be impracticable in the case of luxation. In most of the cases which the writer has witnessed of the fracture traversing obliquely the superior extremity of the shaft of the femur, detaching the trochanters, the foot and whole of the injured extremity were everted, a position it were impossible for the limb to assume, were the globular-shaped head of the bone on the dorsum of the ilium, or placed to- wards the ischiatic notch, and indeed, in the cases which he has seen, with inversion of the limb, the inverted position was not permanent, as when the patient was raised out of bed, and assisted to stand for a few minutes on the sound extremity, the injured limb gradually assumed an inclination forwards and outwards; the inclination, though slight, was always to a degree which it were impossible to give to the limb if the head of the bone were placed on the sciatic notch. Finally, as to the remark- able symptom of inversion of the limb, com- bined with fracture, we have never seen this in- version so rigid as it is in the luxation ; the in- version can be overcome, and we have mostly found that in the cases in which this symptom was noticed, there existed a comminuted frac- ture of the superior extremity of the shaft of the femur, and the limb, if left to itself, would be found sometimes to be everted, sometimes to be inverted, and generally to possess a re- markable degree of flexibility, yielding to any movements the surgeon wishes to communicate to it. Such has been the result of the writer's individual observations on these cases. D. Fractures of the neck of the thigh-hone, with impaction of the superior or cotyloid frag- ment into thecancel luted tissue of the upper extre- mity of the shaft of the femur. — We have spoken of a fracture of the neck of the thigh-bone, in which the fracture runs transversely with respect to the direction of the axis of the neck of the bone, and also of oblique fractures of the cervix femoris (Dupuytren). In the former, i. e. the transverse fracture of the neck, the two opposite surfaces of the fragments are generally fairly confronted to each other, and each presents a granular broken surface ; but instances have been met with in which there existed an inter- locking of these surfaces. A bony spicula or dentiform process, as it were, has been seen to proceed from the broken surface of the superior or cotyloid fragment, and to sink into an alveo- lar-like depression on the upper surface of the lower fragment ; to use the words of Cruveil- hier : " L'engrenement des fragmens s'observe moins souvent, peut-etre dans la fracture intra- capsulaire que dans la fracture extra-capsulaire. Cependant je l'ai observee plusieurs fois ; dans un cas de fracture intra-capsulaire du col, observe sur un adulte tres vigoreux, j'ai trouve un engrenement reciproque forme ainsi qu'il suite le fragment superieur et le fragment infe- rieur presentaient chacun une cavite, et une avance osseuse ; la cavite de l'un recevait l'avance de l'autre et reciproquement, l'engrene- ment etait, qu'il y avait immobilite complete." In the species of fracture which we are now about to consider, the superior or cotyloid frag- ment is firmly impacted into the cancellated structure of the superior part of the shaft of the femur. In this case the limb is shortened somewhat, though not much, and consequently the case may be mistaken for the intra-capsular fracture. When, however, the surgeon endea- vours to bring the limb to its normal length, and to elicit crepitus, or by rotation of the femur he endeavours to ascertain whether the trochanter moves in a larger or smaller circle, he finds that he cannot elongate the shortened limb, nor elicit crepitus by rotation, nor can he learn anything satisfactory by the movement of the trochanter. In general the fracture is com- plete of the compact and reticular tissue of the neck of the bone, and the upper fragment is wedged into the lower, as is the fang of a tooth into its alveolus ; but cases, we believe, have occurred, in which the fracture of the cervix femoris was incomplete, and had engaged merely the under stratum of the compact tissue of the neck of the bone. To comprehend well what occurs in the partial as well as in the im- pacted fracture, we should attend a little to the normal anatomy of the interior of the cervix femo- ris, and the disposition of the compact and reti- cular tissue, a subject the writer has elsewhere stated has been much overlooked, see Dublin Journal, vol. vi. p. 222, from which we quote the following words : " Let us make a vertical sec- tion through the neck of a healthy femur, in the direction of its long axis, and continue it down through the shaft of the dry bone, the section leaving one-half of the femur in front, and the other behind with the lesser trochanter, as has been done in the specimen of the healthy femur of a well-formed adult man, from which Jig. 318 has been taken. This simple view shews us, that the principal strength of the neck resides in an arch of compact tissue, which begins small ABNORMAL CONDITIONS OF THE HIP-JOINT. 807 Fie, 318. where the globular head joins the under part of the neck, but which gradually enlarges down- wards towards the lesser trochanter, and even so low as the middle of the femur, where it will be found nearly twice the breadth of the opposite wall of the shaft of the bone ; the compact stratum which, scarcely thicker than a wafer, invests the entire of the head, upper part of the neck, and trochanter, seems to have little reference to any design of imparting strength or resistance to this portion of the bone, and the same may be said of the whole of the reticular tissue of these processes, while, on the contrary, the compact tissue of the under surface of the neck seems artfully arranged, if we can so say, so as to give support to the weight of the body in the erect position ; hence do we find this compact stratum thrown into an arch, upon which the weight of the body falls, as that of a carriage does on the C spring which sustains it. When we fall or leap from a height on the feet or knees, the thin upper stratum of the neck, and the whole of the reticular tissue of the bone will first receive, and probably yield somewhat to, the weight, by which some of the force of the shock may be decomposed, but to the bony arch of compact tissue, to which we have alluded, must ultimately be referred any violence which the neck of the femur can re- ceive from any impulse transmitted from above. We seldom hear of a fracture of the neck of the femur occurring to a healthy adult when he falls with violence on his feet or knees, for the weight of the superincumbent body is thrown in the most favourable manner on the bony arch of compact tissue before alluded to, which from its density and form, and strength deriva- ble from both, it is almost always able to resist; and even a fracture of the acetabulum or rupture of the capsular ligament and dislo- cation are accidents more likely to happen under these circumstances. But, on the other hand, let us suppose a person to fall on the trochanter major, which is resisted by the ground, while the weight of the pelvis, &c. acting obliquely on the under sur- face of the neck, will have a tendency to bring the neck of the femur into a straight line with the shaft of the bone, or in other words, to efface its obliquity ; here the compact tissue, so often alluded to, receives the force from below in a most unfavourable manner, and this tissue cracks across, and if no more happens for the present, we shall have the simplest form of partial fracture of the neck of the femur. While circumstances are in this state, we can conceive the possibility of a patient being- able to stand after such an accident, and even walk for some distance; and when examined by the surgeon, we can understand how the latter, as it has often happened, might be de- ceived into the opinion that there was really no fracture. Again, we can easily imagine how under such circumstances an awkward move- ment or a fall may render the fracture complete, or how, from a severe secondary injury, or even the continued action of the first impulse, some- what varied in its direction, the upper fragment of the broken neck of the femur could be wedged into the cancelli of the shaft. Anatomical characters of fracture of the neck of the thigh-bone.- — In those cases in which opportunities have occurred of making recent anatomical examinations of those who have died shortly after having suffered fracture of the neck of the thigh-bone, blood has been found extensively extravasated beneath the skin, among the interstices of the muscles, and we find the line of the fractures through the tro- chanters and upper portion of the shaft of the femur itself marked out by blood in a coagu- lated state, which had insinuated itself into and among the interstices of the broken bones. When we examine a case of intra-capsular fracture which had taken place a long time previously to the death of the patient, very remarkable changes in the structures around the joint are noticed. The muscles, when com- pared with those of the opposite side, are more or less atrophied. This observation, however, only applies to the greater number of the muscles around the hip-joint, as some of the smaller ones (in cases of ununited fractures of the neck of the thigh-bone of long standing) are usually found to have undergone a con- siderable change in their appearance and struc- ture; of all these, the obturator externus seems to be the most changed and thickened. This is easily accounted for, uhen we recollect that when the neck of the femur is fractured, there is a strong tendency in the muscles around the joint to drag up the femur, and cause its shortening ; indeed, the capsular ligament and the obturator externus alone resist the ascent of the head of the bone on the pelvis. The tonic force of the muscles has constantly this tendency to elevate the femur on the dorsum of the ilium, and when the patient begins to walk, and to throw 808 ABNORMAL CONDITIONS OF THE HIP-JOINT. his weight on the fractured limb, then it is more particularly that the power of the obtu- rator externus is called into action to restrain the ascent of the trochanter major, which is kept downwards by the obturator and by the strength of the capsular ligament, which under- goes a corresponding change of structure. The capsular ligament has been found semi-cartila- ginous, and occasionally even spiculae of bone have been found in it ; we have also known it to be much elongated, so as to allow the lower fragment to ascend much on the dorsum of the ilium. We have found the capsular ligament usually entire in old cases, but occasionally the bursa, which exists in front of or under the psoas muscle, seems to have freely communi- cated with the interior of the joint. In some cases the natural thickness of the capsule is not much increased; in others it is very con- siderably so. In one of the cases alluded to by Mr. Colles, the capsular ligament was a quarter of an inch thick, in some places half an inch, and it had, at the same time, a firmness of texture which might be termed semicartila- ginous. Two or three particles of bone were found in it. The synovial membrane, where it meets the neck of the femur, has been fre- quently found lacerated in recent cases; in older, inflamed, and in older still, adhesions of the synovial structures to each other have been observed. Thus the head of the fractured femur lias been found adherent to the acetabu- lum, and we have frequently found filamentous adhesions between the synovial membrane of the neck of the bone and the interior of the synovial lining of the fibrous capsule. The synovial membrane, in the normal state, where it invests the narrowest part of the neck of the bone, is thrown into longitudinal plicae or folds; some of the lowest and most distinct of these are denominated by Weitbrecht " retinacula." We do not believe that this accurate anatomist gave this name to these fibro-synovial folds with any practical knowledge of the functions which they occasionally perform in cases of fracture ; but we know very well by experience that, in recent cases of the simple intra-capsular fracture of the neck of the femur, it very fre- quently, if not generally, happens that, although the neck of the femur is broken transversely with respect to its longitudinal axis, the cylin- der of fibro-synovial membrane, which is re- flected over the neck of the bone, is sometimes left unbroken, or is only partially lacerated. The fibrous periosteum, which is here added to the synovial investment of the neck of the femur, strengthens much this part of the mem- brane, and both together, in cases of intra-cap- sular fractures, serve the purpose of keeping nearly in apposition the broken fragments; and in cases in which the greater part of this cylin- drical investment of the neck of the bone re- mains entire, or nearly so, the unbroken mem- brane and the vessels which pass along it must be the medium of vascular communication be- tween the fragments. Thephenomena which extra-capsulnr fractures present are not unlike those which are the result of fractures elsewhere of the femur. We may remark, however, that one of the results of this lesion of the neck of the femur (as it is, in- deed, of almost all other injuries or alterations of structure of this part of the bone) is, that the posterior part of the neck of the femur is diminished one-half in its normal length ; the posterior inter-trochanteric ridge of bone ap- proaches to within half an inch of the circular line which marks the junction of the head and neck of the bone. A large quantity of callus is usually thrown out in the line of the extra- capsular fracture, and the trochanter major be- comes much deformed by it, and the neck so much shortened, that there is danger of the motions of the hip-joint being interfered with. In recent cases in which intra-capsular fracture had occurred, little or no change has been ob- served worth noticing ; but in old cases several phenomena of importance present themselves. 1st, In some cases we find a false articulation to have been formed ; 2dly, there is union of the broken surfaces of the upper and lower fragment by means of ligamentous bands; 3dly, it is reported that complete bony union is effected, but the controversy upon this sub- ject can scarcely be said to be yet terminated. Very soon after intra-capsular fracture has occurred, the surfaces of the broken frag- ments undergo changes ; they are smoothed off by the power of the absorbents, or are mechani- cally rubbed down by the friction of the broken surfaces, or by both these processes combined. In general the neck of the femur disappears altogether, and the basis of the head of' the bone corresponds to the level of the circular brim of the acetabulum. The surfaces are ge- nerally brought into contact by the muscles, and frequently adhesions are formed between the neck of the bone and the internal surface of the capsular ligament, which, as has already been remarked, is greatly thickened ; an oily fluid, resembling natural synovia, is shed over the broken surfaces, and here are all the ele- ments of a false articulation present. The tro- chanters are, in consequence of the removal of the neck of the bone, brought near to the edge of the acetabulum, and bony growths generally shoot out from these processes and from the inter-trochanteric line posteriorly. These bony projections or vegetations sometimes rise as high as the edge of the acetabulum, and when the patient stands or walks, these bony growths rising up from the trochanter are supposed to afford a prop to the pelvis, and thus to assist somewhat the structures which perform the functions of the false articulation. It has been noticed that, in general, the removal of bone from the upper fragment extends as far as the basis of the head and the level of the circular brim of the acetabulum; but in some cases this fragment has been hollowed out. Again, in obedience to influences which we cannot ex- plain, it has happened that the lower surface of the upper fragment formed an uniform convex surface, looking downwards, and corresponded to a large excavation formed in the substance of the great trochanter. This, we find, occurred in one of Mr. Colles's cases : the lower surface of the upper fragment was convex, and covered ABNORMAL CONDITIONS OF THE HIP-JOINT. 809 with spots resembling ivory, while the upper surface of the lower fragment was widely ex- panded into a cup. We have, in our museum, a very remarkable specimen of this abnormal condition of the hip-joint. The upper or coty- loid fragment seems united to the acetabulum by an imperfect anchylosis, while the lower surface of this fragment represents perfectly the half of a sphere looking downwards ; the neck of the femur has been entirely removed, and a cup is hollowed out in the great trochanter to receive the convex surface of the upper frag- ment above alluded to. This surface, as well as the cavity formed in the trochanter, have the polish and hardness of ivory. The history of the case, as to how the functions of the joint had been performed, is unknown. The patient died in the Richmond Hospital, under the care of Dr. Hutton, of a disease unconnected with the chronic affection of the hip-joint. In the examination of old cases of intra-eapsular frac- ture, we have found the capsular ligament short and strong, as already mentioned, and that it retained the trochanters close to the brim of the acetabulum, the cervix femoris having been altogether removed. In a case which Mr. Bra- bazon and the writer examined lately, of an old woman who had fractured the neck of her femur several years before her death, and in whom there was shortening of the extremity for two inches and a half, the neck of the femur had altogether disappeared to its base The surface on the internal part of the shaft of the femur, from which the neck of the bone nomi- nally springs, was plane and smooth, and no vestige even of the lesser troeVianter existed. The under surface of the globular-shaped head of the femur was removed to the exact level of the brim of the acetabulum, in which the re- mainder of the head was still retained by an inter-articular ligament, which seemed to have been reduced to the structure of loose cellular membrane. The acetabulum of this side, too, was evidently smaller than that of the opposite side, and the cartilage covering it, and that also investing the remnant of the head of the bone, were partially removed. From want of use, it would appear that all these parts were in a state of atrophy. In this respect there was a correspondence between the internal and exter- nal structures of the broken limb, for the whole extremity was deformed, shortened, and, as is usual, much reduced in size when compared with the opposite limb. Union by means of a ligamento-cartilaginous substance is by no means uncommon. In this case, as in almost all others, the neck of the thigh-bone altogether disappears, and the trochanters are brought up to the level of the acetabulum, which still re- tains the remnant of the head of the bone. The broken surfaces are united closely enough to each other by a fibrous substance, and this union is sufficiently analogous to that which we frequently see in cases of fractured olecra- non or_patella. We have spoken of a species of fracture which is called the impacted fracture. In this case the femur is broken generally at the basis of the neck, not far from the inter-trochanteric lines : sometimes it is only the under part of the neck which is broken, and then the frac- ture is only partial ; but generally the compact tissue all round this portion of the neck is, by an accident, cracked across, and the superior fragment, that is, the whole of the cervix femoris, is impacted into the cellular structure of the superior extremity of the shaft of the femur (figs. 319, 320). The limb is shortened half an inch, and in general everted. In the Dublin Hospital Reports, vol. ii. Mr. Colles has given a aood delineation of this species of fracture. In Sir A. Cooper's work, also, similar specimens maybe seen of this impaction of the upper frag- ment. " La realite de ce fait interessant" seemed new to the editors of Dupuytren's " Lemons Orales,'' in 1832, in which we find it stated that the superior fragment of the broken neck of the thigh-bone is sometimes driven into the thick- ness of the spongy texture of the superior ex- tremity of the inferior fragment, and the conso- lidation is effected readily enough. To con- clude in the words of the Lecons Orales : " plusieurs pieces d'anatomie pathologique, tirees du Museum de l'Hotel Dieu, et represen- tant les fragmens ainsi consolides, ont ete mon- trees a l'amphitheatre, et ont convaincu chacun de la realite de ce fait interessant. II est utile de noter cette cause de deviation; elle peut rend re compte, suivant les cas, de quelques faits exceptionnels de deviation du pied en dedans dans la fracture du col du femur, faits excep- tionnels, qui ont ete observes par plusieurs auteurs."* In the museum of the Richmond Hospital we have some specimens of this frac- ture. Fig. 319 represents a section of the supe- Fig. 319. rior extremity of the femur of a woman who met with this species of fracture. The history of her case, as recorded in the catalogue, is as follows :— " Mary M'Manus, a;t. 52. Fracture of the neck of the femur external to the cap- sule. The upper fragment has been driven down, and has become firmly impacted in the cancelli of the shaft of the bone. The trochan- * Lemons Orales, torn. ii. p, 100. 810 ABNORMAL CONDITIONS OF THE HIP-JOINT. ter minor is split, the fissure passing at right angles with the body of the femur. The de- scending ramus of the pubis was broken ob- liquely, the fracture passing downwards and inwards from the thyroid foramen. There was a large effusion of blood into the crushed can- celli of the bone. Tlie patient, from whom the preparation was taken, was thrown down by a cart loaded with hay. The horse and cart passed over her. The injured limb was short- ened three quarters of an inch, the foot was everted, and the slightest motion was painful. She died on the fourth day after the occurrence of the accident, having never recovered from the shock." Another specimen (Jig. 320) shews Fig. 320. this species of fracture in the case of a woman who survived the accident. " Alicia Sherlock, aet. 64. Section of the head and neck of the femur, shewing fracture of the cervix external to the capsule. The neck of the bone has sunk nearly to a right angle with the shaft. The compact structure which lines the concavity of the cervix has been broken, while the very thin stratum which invests the upper surface has yielded to the force without breaking, but the cervix has sunk into the cancellated texture of the shaft at a right angle, and is now sup- ported upon the lesser trochanter. There is no motion whatever between the broken surfaces, nor the slightest trace of fracture at the central part of the neck of the bone. The injury was produced by a fall on the trochanter. There was but little alteration in the position of the foot, but the tendency was to eversion. The shortening amounted to half an inch, and cre- pitus was not distinguishable. The patient lived three months and a half after the receipt of the injury." In both these cases we have a confirmation of our opinion, that the reduction of the compact arch of bone which occupies the under surface of the neck of the femur to a thin lamina, predisposes to fracture of this por- tion of the neck of the thigh-bone. In the case in which the examination was made four days after the accident (Jig. 319) we find, of course, that there was no osseous deposition around the inter-trochanteric lines, but that, on the contrary, in the case, A. Sherlock, (Jig. 320), which survived the accident for more than three months, exuberant growths of bone surrounded the seat of fracture, and contributed to form a kind of socket, which received the superior fragment, by means of which the patient was enabled to throw her weight on the injured limb, and even to walk. The lesser trochanter, in most of the cases which we have examined, was greatly increased by bony depositions, and became a prop to support the head, and it is probable that, in these cases, the acetabulum is propped up by the growths of bone from the shaft of the femur. " This is a mode of union," says Mr. Colles, (alluding to the impaction,) " very little inferior to callus in point of firm- ness, but very different in its nature," and which, he conceives, is peculiar to fracture of the neck of the thigh-bone. In these cases Mr. Colles has found a thin cartilaginous plate every where interposed between the neck and shaft. The new osseous production could have very little assisted in keeping the fractured pieces in apposition, for it was principally thrown out about the trochanters, a small por- tion only being formed below the neck, yet the motion allowed between the fragments was so very inconsiderable, that it required a close in- spection to discern it, so that, in this instance, the new osseous matter contributed very little to the consolidation of the broken bone, the firmness of which (inferior only to bony anchy- losis) must therefore be ascribed entirely to the interposed thin plate of cartilage. In one of Mr. Colles's cases, No. XI. a vertical section shewed that the neck had been fractured near to the trochanters, and lay across the top of the shaft ; its broken extremity being in contact with the outer plate of the shaft. The external solid walls of the neck were very thin* In a specimen of fracture of the cervix femoris, which we possess in our museum, the neck of the bone has been broken at its basis, near the inter-trochanteric lines, and was impacted nearly transversely into the cancellated structure of the shaft of the femur, and the force of the fall was so considerable that the upper fragment has absolutely penetrated the outer wall of the tro- chanter, and would have been in naked con- tact with the tendon of the gluteus maximus, had it not been for the existence of the bursa there situated. From the specimens that we have examined, and have in our possession, we entertain no doubt but that solid bony union may take place between the impacted cervix femoris and the superior extremity of the shaft of the femur. In all cases of the impacted fracture, when the patient had survived the accident for a month or more, whether the union was complete or incomplete, exuberant growth of bone had sprung from the inter-trochanteric lines. Does bony consolidation of the intra-capsular fracture of the cervix femoris ever occur? — This question has for the last twenty years been * Dublin Hospital Reports, vol. ii. p. 351. ABNORMAL CONDITIONS OF THE HIP-JOINT. 811 much agitated; Desault, Platna, and John Bell long ago expressed their opinion that a fracture within the capsular ligament would not admit of union by callus. Sir A. Cooper in his Treatise on Dislocations and Fractures (p. 127) says, " In all the examinations which I have made of transverse fractures of the cervix femo- ris entirely within the capsular ligament, I have never met one in which a bony union had taken place, or which did not admit of motion of one bone upon the other. To deny its possibi- lity and to maintain that no exception to the general rule can take place would be presump- tuous, especially when we consider the varieties of direction in which a fracture may occur, and the degree of violence by which it may have been produced; as, for example, when the fracture is through the head of the bone and there is no separation of the fractured ends, or when the bone is bioken without its periosteum, and the reflected ligament which covers its neck torn, or when it is broken obliquely, partly within and partly externally to the cap- sular ligament ; but all I wish to be understood to say is, that if it ever does happen, it is an extremely rare occurrence, and that I have not met a single example of it." Sir A. Cooper's opinions, when they were published, particularly in Paris, excited as- tonishment, and many observations were made in the clinical lectures and works of the day upon the supposed error of the doctrine, that the intra-capsular fracture of the neck of the thigh-bone was not susceptible of bony consoli- dation. Messrs. Roux, Dupuytren, and others contended that they had treated many cases of the intra-capsular fracture of the neck of the thigh-bone successfully, and that bony consoli- dation had been effected, and besides shewed to their classes what they considered as decided examples of such union of this fracture. They did not content themselves by referring to living cases, because these were likely to be ques- tioned, but they produced various specimens obtained by post-mortem examinations of per- sons who had recovered from the effects of the fracture, but had died of other disease. Some of these specimens were examined by Mr. Crosse, and some were sent to London to Sir A. Cooper, but they failed to convince either Mr. Crosse or Sir Astley that they were true instances of the infra-capsular fracture consoli- dated by bone. We may say the same of some preparations in the museum of the Royal Col- lege of Surgeons, London, which were supposed to be proofs of a bony union of the neck of the thigh-bone subsequent to a fracture within the capsular ligament, but says Mr. Wilson, " I have attentively examined these two preparations, and cannot perceive one decisive proof in either of the bone having been actually fractured." One of these cases was published in the Edinburgh Medical and Surgical Journal as an example of united fracture. The writer has known many speci- mens adduced as proofs of bony consolidation of the intra-capsular fracture of the neck of the thigh-bone, which, upon examination, were found to have been the result of disease. The neck of the thigh-bone, we know, is greatly shortened when the hip-joint is the seat of that abnormal change which we have stated to be the result of chronic rheumatic arthritis, but in this case the previous symptoms, the history of the case, and when these cannot be collected, the state of the acetabulum and other appear- ances, sufficiently point out the difference. Again, the effect of senile degeneration of the cervix femoris is very liable to be mistaken for an united intra-capsular fracture. In this, however, the history of the case, the co-existence of the same condition on both sides, the pene- tration of the interior of the attenuated cellular structure by an oily medulla, and other charac- ters of the senile degeneration, will serve to prevent false conclusions. Lastly, we have also frequently known specimensof the impacted frac- ture, where the whole cervix has been firmly driven into the substance of the great trochanter, mistaken for examples of bony union of the in- tra-capsular fracture. The quantity of callus that is in these cases added to the great and lesser trochanters, which encloses the impacted neck of the bone, is calculated on a superficial exami- nation to induce erroneous conclusions, but a section of the bone, as represented in fig. 320, will explain the true nature of the case. Various cases have been laid before the pub- lic and read before different learned societies, which have been considered as very decided evidences of bony consolidation of the intra- capsular fracture of the neck of the femur. Case 1. — In the year 1827 Mr. Langstaff presented to the Medico-Chirurgical Society of London a specimen of what he considered to have been an intra-capsular fracture united by bone. The case was that of a woman who was 50 years of age when the fracture occurred. She was confined for nearly twelve months to bed after the injury, and during the remainder of her life, that is, for ten years, she walked on crutches. On dissection it was found that the principal part of the neck of the femur was absorbed, and the head and remaining portion of the neck were united principally by bone, and partly by a cartilaginous substance. The capsular ligament was immensely thickened and embraced the joint very closely, the carti- laginous covering of the head of the bone and acetabulum had suffered partial absorption, the internal surface of the capsular ligament was coated with lymph. On making a section of the bone, it was evident that there had been a fracture of the neck within the capsular liga- ment, and that union had taken place by osseous and cartilaginous media. With a view of ascer- taining whether there was real osseous union the bone was boiled many hours, which discoloured it, but by destroying all the animal matter it satisfactorily proved the extent and firmness of the osseous connexion, and the vacant spaces occupied with cartilaginous matter. These appearances are represented by a drawing made shortly after boiling.* Case 2. — Dr Brulalour, surgeon to the hos- pital at Bourdeaux, sent to London the parti- * Vol. xiii. of the Society's Transactions. 812 ABNORMAL CONDITIONS OF THE HIP-JOINT. culars of a case of fracture of the neck of the femur, whicli were read before the Medico- Chirurgical Society on the 5th of June, 1827. The following is an abstract of it. Dr. James, an English physician, set. 47, in good health, was thrown from his horse on the 20th of March, 1826. He fell directly on the great trochanter, but got up and walked a step or two, which occasioned such acute pain in the hip-joint that he instantly fell again. On examination im- mediately after the accident, Dr. Brulalour observed the principal signs of fracture of the neck of the femur. Extension of the limb was kept up for two months so as to preserve it of its natural length. He recovered the full use of the limb so as to be able to walk without any assistance, even that of a cane. Dr. James, on the 20th of December, about nine months after the accident, was attacked with hasmate- mesis, which in two days terminated fatally. The post-mortem examination of the right coxo- femoral articulation shewed — 1st, the capsule a little thickened; 2d, the cotyloid cavity sound ; 3d, the inter-articular ligament in a natural state; 4th, the neck of the femur shortened, from the bottom of the head to the top of the great trochanter was only four lines, and from the same point to the top of the small trochanter six lines ; 5th, an unequal line sur- rounded the neck, denoting the direction of the fracture; 6th, at the bottom of the head of the femur and at the external and posterior part considerable bony deposit had taken place. A section of the bone was made in a line drawn from the centre of the head of the femur to the bottom of the great trochanter so as perfectly to expose the callus. The line of union indi- cated by the callus was smooth and polished as ivory. The line of callus denoted also that the bottom of the head of the femur had been broken at its superior and posterior part. Case 3. — Mr. Stanley, surgeon to St. Bar- tholomew's Hospital, in May 1833 read before the Medico-Chirurgical Society of London a case of bony union of a fracture of the neck of the thigh-bone within the capsule, occurring in a young subject a;t. 18. In the examination of the body of this young man, who died of what was considered to be small-pox about three months after the accident of the hip-joint, no other morbid appearances were discovered besides those of the injured hip-joint. The capsule of the joint was entire but a little thickened, the ligamentum teres was uninjured, a line of fracture extended obliquely through the neck of the femur, and entirely within the capsule, the neck of the bone was shortened, and its head, in consequence, approximated to the trochanter major. The fractured surfaces were in the closest apposition and firmly united, nearly in their whole extent, by bone. There was an irregular deposition of bone upon the neck of the femur, beneath its synovial and periosteal covering along the line of the fracture. Mr. Stanley adds, " the foregoing case is re- markable from the occurrence of a fracture of the neck of the femur within the capsule at an early age, and it is, I believe, the only example of it on record." Sir A. Cooper has published a letter in the Medical Gazette, April 1834, vol. xiv., which is intended to explain his sentiments upon this subject, and to set the profession in general and the French surgeons in particular right as to the conceptions formed of the doctrine he held as to the susceptibility of the bony con- solidation of the intra-capsular fracture. In it we find the following case. Case 4. — Mrs. Powell, aged above 80 years, fell down in the afternoon of the 14th of No- vember, 1824. Sir Astley Cooper saw her soon after, and found her complaining very much of pain in the left hip. The limb could be moved in every direction, but this motion produced excessive pain. She lay on her back with the limb extended, and nothing whatever was done, except to apply fomentations, in the first few days. He believed there was a fracture of the neck of the thigh-bone although the limb remained quite as long as the other, and he could per- ceive neither a crepitus nor any altered appear- ance in its position, except a slight inclination of the toes outwards. She had more constitu- tional irritation than Sir Astley ever observed from a similar accident. She suffered much pain in the hip, and was in consequence obliged to take an opiate, but she got very little rest. She generally had much thirst. There was the utmost difficulty in keeping her bowels open, and she had great pain and difficulty in making water. She had no appetite for common food, and for three weeks appeared so weak that she was under the necessity of taking wine and brandy. For some time all her urine and stools were passed in bed, but not involuntarily, and only because she could not be persuaded to use proper means ; in consequence her back became very sore. Latterly she complained of pain in the abdomen, which was very tender on pressure, and even the weight of the bed- clothes was inconvenient. Her tongue became very dry and brown, and the last twenty-four hours she was insensible. She died on the morning of the 19th December about five. Examination. — This took place at seven in the evening. There was some ecchymosis amongst the muscles about the injured part and in the cellular membrane about the sciatic and anterior crural nerves. The greatest part of the fracture of the neck of the thigh-bone, which was entirely within f8e capsular ligament, was firmly united. A section was made through the fractured part, and a faint white line was perceived in one portion of the union, but the rest appeared to be entirely bone. This case, says Mr. Swan, beautifully shews the principle which Sir A.Cooper has advocated, viz. that when the reflected ligament remains whole, and the bones are not drawn asunder, the nourishment to the head of the bone continues, and union will be produced even in the short space of five weeks, by only placing the knee over a pillow, and in other respects leaving the case to nature. We find Mr. Samuel Cooper is of opinion that a bony consolidation of the intra-capsular fracture is proved. He says,* " Sir A. Cooper * Surgical Diet. p; 575, last ed. ABNORMAL CONDITIONS OF THE HIP-JOINT. 813 has satisfied himself that osseous union some- times takes place, and he has in his own col- lection a most unequivocal specimen of it, which he was kind enough to show me two years ago. The possibility of bony union is now universally acknowledged, but the cure in this way is far less frequent than that by means of a ligamentary connexion."* It does not appear to us that this question is yet so entirely settled as the last writer's obser- vations would lead us to imagine ; although in this city (Dublin) the subject has been care- fully investigated for many years, we do not find our museums yet contain a single speci- men of the intra-capsular fracture united by bone. In Paris we find Cruveilhier, one of the most eminent pathologists in France, ex- pressing himself in the most unreserved manner, that a bony consolidation of the intra-capsular fracture was impossible. Not unaware, as must be supposed, of the eight cases referred to by his pupil, M. Chassaignac,f (amongst which are those of Langstaff, Stanley, and Sir A. Cooper,) Cruveilhier, to whom Chassaignac's memoir is dedicated, thus expresses himself: — "Je suis porte a considerer comme des cas de deforma- tion de la tete et du col, la plupart, si non la totalite desfaits, que Ton invoque gen6ralement pour etablir la reunion de fractures intia-cap- sulaires du col du femur, a. l'aide d'un cal os- seux, le cal est impossible, parceque les frag- menslibres, au milieu de la synovie, ne sont point entoures des tissues charges de la reparation de la solution de continuite." Thus not content with asserting that bony union is impossible, lie further adds that he is convinced from nu- merous pathological observations, and from ex- periments on animals, that the ideas of bony union by means of a first, a provisional callus, and then by means of a final callus, are erro- neous; he is certain that there is but one and the same callus, which passes through different stages of development, until the ossification is complete ; he is of opinion that the ends of the broken bone, no matter how confronted or held together, never are directly united. This union, he thinks, can only take place through the in- tervention of callus, which is always thrown round the bones where fractured, like a clasp or bony ferule ; therefore, he reasons, the cause of the difference between the intra-capsular and extra-capsular fractuffi, with reference to their susceptibility of b(my consolidation, is, that in the first the fragments are as it were abandoned to themselves to effect an union ; here there is no bony ferule or clasp possible, while in the second the fragments are in the same condition as in all other fractures; that is to say, they are surrounded by soft parts, by the ossification of which the bony clasp is formed. Thus does he not only deny the possibility of bony conso- lidation in the case of the intra-capsular fracture, but endeavours to explain why the union is impracticable. We cannot agree with this eminent patholo- gist in the observations that the ends of the * Loc. cit. t De la Fracture du col du femur. Par E. Clias- saignac, M.D., Paris, 1835. bones themselves take no part in effecting a bony union, for in cases of impacted fracture alluded to by us in a preceding article, particu- larly in the case of Sherlock, from which fig. 320 has been taken, bony consolidation had taken place in almost the whole line of the fracture, and could only have been effected by the union of the two bony surfaces which were confronted to each other. No doubt the union here was further fortified by the external effusion of new callus, which surrounded the bone at the seat of the fracture. When we re- flect on the cases adduced in proof of the bony consolidation of the intra-capsular fracture, we must either disbelieve the facts, or admit that the union is not impossible. It would have been satisfactory if the test by boiling the specimens of the united fractures had been resorted to in all these cases, as it had been in Mr. Langstaff's ; this observation par- ticularly applies to the case reported by Dr. Brulalour. of Bourdeaux. We find in Chas- saignac's report of this same case, taken from the memoir sent to the Academy of Medicine of Paris, (Seancedu 16 Avril, 1827) in alluding to the specimen in question he says: — "Scie, dans toute sa longueur le cal se presentait sous la forme d'une ligne oblique, raboteuse, d'une couleur moins blanche etd'un consistence un peu moins ferme que le reste de l'os.'' We had thus far entered into this much agi- tated question, when an interesting opportunity occurred to us of making the post-mortem exa- mination of a case of united intra-capsular fracture. The history of the case was this: — Owen Curran, set. 70, was for the last five years an inmate of the pauper department of the House of Industry; he was very infirm on his limbs, and his mind was in a state of dotage; on the 1st of August, 1837, while walking across his ward, he fell on his right side ; he was unable to rise, and complained of pain in his right hip ; he was carried to bed, and was immediately visited by the late Mr. William Johnstone, who was then acting for me as clinical pupil, who found the limb everted, and only half an inch shorter than the other. Mr. Johnstone considered the case a fracture of the cervix femoris, which required no other surgical treatment than that of placing and preserving the limb in a semiflexed po- sition over pillows. The old man suffered but little pain in the injured part, at all events he did not complain of it. In about five weeks after the accident he was raised out of his bed, and when placed standing, he was able to put the heel of the injured limb to the ground. On the 30th of September, that is, about eight weeks after the accident, my friend Mr. Smith entered in his note-book the following memo- randum of this case : — " As the patient lies in bed he can elevate the injured limb by the un- assisted efforts of its own muscles. The ever- sion is slight, and the degree of shortening amounts to one inch ; no force can bring the limb down to the length of the other. From the history and symptoms, this seems to have been a case of impacted fracture." This man survived the accident one year and nearly 814 ABNORMAL CONDITIONS OF THE HIP-JOINT. ten months, during which time he was con- tented to remain most of the time in his bed, but when placed on his feet, could stand very well, and was able but unwilling to walk. On Tuesday the 20th of May he got an attack of bronchitis, which, the following Friday, ter- minated fatally. At twelve o'clock, on Satur- day, the 25th May, assisted by Mr. Brabazon and some of the pupils of the hospital, I made an examination of the body. The right leg and thigh were much everted. The trochanter major was elevated, and projected much out- wards; the degree of shortening just amounted to one inch ; the muscles presented a healthy appearance, the capsular ligament was of a yel- lowish colour, and somewhat thickened. The femur was removed from the acetabulum ; this / latter cavity presented a healthy appearance, ex- cept towards the margin of it; here the cartilage was softened. The round ligament was sound. The head and neck of the bone had lost their normal obliquity, and were directed nearly ho- rizontally inwards (fig. 321); the cervix pre- sented, both anteriorly and posteriorly, evidence of a transverse intra-capsular fracture having oc- curred ; the globular-shaped head was closely approximated behind and below to the posterior intertrochanteric line, and to the lesser trochan- ter, so that the neck seemed altogether lost except anteriorly, where a very well-marked ridge of bone shewed the seat of the displace- ment and of the union of the fragments. This ridge is evidently the upper extremity of the lower fragment of the cervix. The fracture of the neck posteriorly was found to have been closer to the corona of the head than anteriorly, and the fibro-synovial fold in the former situa- tion remained unbroken. A section has been made of the bone through the head, neck, and trochanter ; one portion has been subjected to maceration and to boiling ; and the bony union has been unaffected by these tests. Scarcely any portion of the neck can be said to have been left. Fig. 322. The section, 322, shews the compact line which denotes the union of the fragments ; the head and shaft seem to be mutually impacted into each other, and almost the whole of the cervix has been absorbed ; the line of union is serrated, solid, and immoveable; and the cells of the head and substance of the shaft seem to communicate freely in all places, except where the thin line of compact tissue here and there points out the seat of the welding together of the remaining portions of the head and neck of the femur. The bone was in its recent state, on the 25th of May, laid before a meeting of the Patho- logical Society. It seemed to be the univer- sal opinion of the members present that it was a decided specimen of the intra-capsu- lar fracture of the cervix femoris, which had been solidly united by bony callus. This case may be adduced in formal contradiction to the observation and theories of that very emi- nent pathologist, Cruveilhier. It cannot be said to invalidate the more guarded opinions of Sir A. Cooper, who, in his observations upon this subject, distinctly stated that " he would not be understood to deny the possibility of union, when the bone was broken, without its periosteum and reflected^gament being torn, or when there was no separation of its fractured ends." Cases such as the foregoing are certainly rare, but they appear to the writer to belong to the class of impacted fractures; they differ from those alluded to in the foregoing article merely in this, that in the former the fracture of the cervix takes place at its basis near the trochan- ters, and that, in the latter, the fracture occurs near to the head of the bone, and is thus en- tirely intra-capsular, or rather may be considered as fractures of the intra-capsular portion of the cervix femoris. The question then, viz. does bony consolidation of the intra-capsular frac- ture of the cervix femoris ever occur? seems to us replied to in the affirmative. When an impaction of one, or a mutual ABNORMAL CONDITIONS OF THE HIP-JOINT. 815 impaction of both of the fragments has taken place, then under such peculiar circumstances a firm bony consolidation of the fragments may be expected. Finally, although this is not the place to speak of the surgical treatment of such cases, we may remark that the most valuable practical information, in our mind, derivable from the discovery of facts like the foregoing, is that the lenient method of treatment, viz. by position alone, and without splints, may be eminently successful, so far as the accomplishment of a firm reunion of the fragments is concerned. II. Luxations. — Luxations of the head of the femur from the acetabulum are by no means so frequent as fractures of the bones which enter into the composition of the hip-joint. This comparative immunity from this form of accident arises from these circumstances, — that the acetabulum which lodges the head of the femur has great depth, and that the fibrous membranes which secure this bone in the coty- loid cavity have great strength, and restrain within certain limits its movements. Indepen- dently, however, of congenital luxations, and of those which are the result of disease, there are six distinct forms of dislocation of the hip- joint to be described as the result of accident alone. The dislocations of the head of the femur from accident may be classed as follows: — a. dislo- cation upwards and backwards on the dorsum ilii ; b. directly backwards towards the ischiatic notch ; c. downwards and inwards into the foramen ovale ; d. upwards, forwards, and in- wards on the horizontal ramus of the pubes. Besides these, of late years two more unusual luxations have been described and verified by post-moitem examinations, viz. dislocation downwards towards the tuberosity of the ischium, and dislocation upwards between the anterior inferior spine of the ilium and the ilio- pubal eminence. a. Dislocation of the head of the t femur upwards and backwards on the dorsum, of the ilium. — When the head of the thigh-bone is thrown on the dorsum ilii, the limb on the luxated side is from one to two inches shorter than the other ; the thigh is slightly flexed, or a little advanced upon the other, and carried into a slate of abduction, and of marked rotation inwards. The. patella and inner side of the dislocated limb look directly inwards, and the great toe corresponds to the tarsus of the opposite foot. The great trochanter, carried forwards and upwards, approaches the crest of the ilium and its anterior and superior spine, and forms there a very well marked tumour; the nates raised up by the head of the femur is very salient towards its superior and posterior part. If we make attempts to bring the limb backwards into a state of extension or abduc- tion or of rotation outwards, we find we give much pain to the patient, and that we cannot move the bone in any of these directions. We can, without causing suffering to the patient, augment a little the flexion towards the abdo- men, and adduct the dislocated thigh, and we can also increase the rotation inwards already existing, or, to use the words of Sir A. Cooper, " when the leg is attempted to be separated from the other it cannot be accomplished, as the limb is firmly fixed in its new situation, so far as regards its motion outwards. The thigh can be slightly bent across the other and towards the abdomen, but extension of the thigh and rotation outwards are impossible." Rotation inwards, on the contrary, is to a great extent permitted, so much so indeed that we have seen the back part of the heel turned forwards, while the toes pointed backwards. During these extreme motions of rotation inwards, if the hand be pressed on the dorsum of the ilium deeply, the head of the femur will be perceived to roll on the ilium, and its tro- chanter major also can at this time be felt to be nearer than natural to the anterior superior spinous process of the ilium ; the trochanter is less prominent than that on the opposite side, for the neck of the bone and the trochanter are resting in the line of the surface of the dorsum ilii. Upon a comparison of the two hips, the roundness of the dislocated side will be found to have disappeared. A surgeon, then, called to a severe and recent injury of the hip-joint, looks for a difference in length, change of posi- tion inwards, diminution of motion, and de- creased projection of the trochanter. The explanation of the manner in which the dislocation of the head of the femur upwards and backwards on the dorsum ilii takes place has been the subject of some difference of sen- timent. The late Mr. Todd has, in ouropinion, given some judicious observations on this sub- ject ; * he says, " the elementary work on luxa- tions most generally read and referred to in this country, is Dr. Farrell's translation of Boyer's Lectures, arranged by Richerand. The following is the description therein given of the manner in which the luxation of the femur, at present under consideration, is produced. " When by a fall from a place, more or less elevated, on the soles of the feet, or on the knees, the thigh is pushed forwards and inwards, the head of the femur, forced to- wards the superior and external part of the acetabulum, breaks the internal and orbicular ligaments, escapes through the laceration in the latter, and ascends on the external face of the os ilium ; but as the part of the os ilium immediately above and at the external side of the cavity is very convex, the head of the femur soon abandons its first position, and slides backwards and upwards into the ex- ternal fossa of the os ilium, following the in- clination of the plane towards the fossa, and obeying the action of the glutsei muscles, which draw it in this direction. The head of the femur, in ascending thus on the ex- ternal face of the os ilium, pushes upwards the glutaeus minimus, which forms a sort of cap for it, and the glutaeus maximus and me- dius are relaxed by the approximation of the points into which they are inserted. The pyri- formis is nearly in its natural state; the gemini, obturatores, and quadratus femoris are a little * Dublin Hospital Reports, vol. iii. p. 397. 816 ABNORMAL CONDITIONS OF THE HIP-JOINT. elongated. The psoas magnus and iliacus in- ternus are relaxed, as are also tlie other muscles inserted into the trochanter minor."* From the foregoing opinions Mr. Todd dis- sents in the following words : — " To admit of the head of the femur being ' forced towards the superior and external part of the aceta- balum,' and of its ascending ' on the external face of the os ilium,' it will be obvious to those who carefully examine the mechanism of the articulation, that the thigh must be ex- tended on the trunk, and the dislocating force applied externally and inferiorly, so as to pro- duce what may be termed an excess of ad- duction. To the limb assuming such positions, which appear to me to be quite essential to- wards the production of this dislocation in the manner described by Bayer, some considerable obstacles exist. In the first place, I believe it seldom happens that a person who falls from a height will reach the ground with the thigh extended on the trunk ; in the descent the superior power of the flexor muscles will pre- dominate, and at the moment of the appli- cation of force to the limb it will be more or less in a bent position. It is scarcely neces- sary to observe that this circumstance must materially influence the direction in which the head of the bone will be protruded from the articulating cavity. " Secondly, should the thigh and leg be com- pletely extended at the time that the force is applied, it is probable that the other limb will be extended also, and will thus prevent a move- ment of the stricken limb inwards beyond a certain point ; or, in other words, the opposite limb will prevent that extent of adduction inferiorly which is necessary to remove the head of the femur from the acetabulum, and to admit of its being forced upon the anterior convex surface of the dorsum ilii. But whether the opposite limb be extended or not, it must oppose a certain limit to adduction, if that term can be applied with propriety to a lateral movement of the lower extremity, by ■which it is carried beyond the middle line of the body. " Sir Astley Cooper attributes this direction of the limb to the circumstance of the injury being inflicted when the knee and foot are actually turned inwards ; however, it appears to me that muscular action is also in favour of the limb assuming this position. " If it be admitted that the thigh is generally in a state of demiflexion when the force causing this dislocation is applied, it must also be ad- mitted that in this state the pyriformis, ob- turatores, and gemini have but little effect as rotators, the power of these muscles as such being greater or less, according as the junction of their fibres with the femur approaches or deviates from a right angle ; and that the power of the anterior portion of the glutaeus medius and of the tensor fasciae lata?, as rotators inwards, is increased in this position, the angle which their fibres form with the thigh-bone being augmented ; thus the last- * Lectures of Boyer, p. 156. mentioned muscles will appear to possess much influence in determining the inverted po- sition of the limb, as they must draw forwards the trochanter major and external side of the thigh, at the moment in which the head of the bone escapes from the acetabulum. " The inclination of the thigh forwards and inwards which constitutes so remarkable a fea- ture of this dislocation, may be attributed partly to the tension of the psoas magnus, the iliacus internus, and the pectinalis, and also to the peculiar form of the surface of the pelvis, to which the upper part of the femur is applied ; but certainly not as Mr. Samuel Cooper has asserted, to the tense state of the triceps and gracilis, for these muscles are re- laxed." Anatomical characters of the taxation (if the head of the thigh-bone on the dorsum ilii. — The appearances which have been noticed in the anatomical examination of the hip-joints of individuals who, having had a luxation of this articulation, have died very soon afterwards of other severe injuries received at the same time, may be collected from the study of some facts of this nature already published. Of these none gives us a better idea of the recent effects of a dislocation upwards and backwards- on the dorsum ilii than the case related by the late Mr. Todd, in the third volume of the Dub- lin Hospital Reports, which is as follows : — Case. — In the summer of 1818, a robust man, in attempting to escape from his bed- room window in the second floor of a lofty house, fell into a flagged area, by which acci- dent his cranium was fractured, and his left thigh dislocated upwards and backwards. The dislocation was reduced without diffi- culty ; however, an extensive extravasation of blood having taken place on the brain, the patient lingered in a comatose state for about twenty-four hours, and then died. On the day after dissection was performed, and the following appearances were observed in the in- jured joint and the parts contiguous to it. On raising the glutaeus maximus, a large cavity filled with coagulated blood was found between that muscle and the posterior part of the glutaeus medius. This was the situation which had been occupied by the dislocated extremity of the femur. The gluteus medius and minimus were uninjured. The pyriformis, gemini, obturatores, and quadratus were com- pletely torn across. Some fibres of the pec- tinalis were also torn. The iliacus, psoas, and adductors were uninjured. The orbicular liga- ment was entire at the superior and anterior part only, and it was irregularly lacerated throughout the remainder of its extent. The inter-articular ligament was torn out of the de- pression on the head of the femur, its attach- ment to the acetabulum remaining perfect. The bones had not sustained any injury. Cruveilhier, in the 28th and 29th livraisons of his valuable work on Pathological Anatomy, has given two cases of what he considers to be old luxations of the head of the femur up- wards and outwards on the dorsum ilii, which had been left unreduced ; the history of these ABNORMAL CONDITIONS OF THE HIP-JOINT. 817 cases was unknown. When we carefully ex- amine the author's account of them, and refer to the eight accompanying drawings he has given of them, doubts may well arise in the mind as to whether these are to be considered congenital luxations, or the result of accidents which had occurred after birth. The author does not himself seem free from suspicion on this matter, for, in commencing his observa- tions on the pathological anatomy of cases of luxation of the femur on the dorsum ilii, upwards and outwards, he says, " elles sont tantot congeniales, tantot posterieurs a la nais- sance. Existe-t-il des differences notables entre les unes et les autres sous le point de l'anatomie pathologique ? II m'est permis d'en douter jusqu'a ce que des faits positifs aientetabli le contraire." We have in some of the preceding pages adduced what we have considered positive proofs that the anatomical characters of the congenital luxation of the hip- joint are altogether peculiar, and the appearances either in the living or the dead are in our opinion by no means to be confounded with those which are the result of luxations which have occurred after birth, and have been left unreduced. When opportunities have occurred of exa- mining the hip-joints of those who have for many years survived a dislocation of the head of the femur upwards and backwards on the dorsum ilii, and which had been left unre- duced, remarkable changes have been noticed to have taken place in the bones and surround- ing structures. Muscles. — The muscles of the dislocated hip have been found for the most part in a state of comparative atrophy, and the direction of their fibres has of course been altered by the ascent of the superior extremity of the femur. Among the muscles of the hip-joint the con- dition of the gluteus minimus has been most dwelt on by authors. It is stated on the respectable authority of Boyer, that when the head of the femur is dislocated upwards and backwards on the dorsum ilii, it passes between the external iliac fossa, and the little gluteus ; that it carries this muscle up, and is as it were capped by it (" pour ainsi dire coiffee"). This muscle, he elsewhere adds, envelopes imme- diately the head of the femur ; it undergoes very remarkable changes ; it becomes pale ; ■its fibres disappear almost entirely, and are changed into a fibrous substance which is firm and solid, and which has been sometimes seen converted into bone. Cruveilhier seems to have adopted Boyer's idea as to the change this muscle undergoes in these cases. But if it be true, as we believe it is, that at the moment the luxation we are now considering occurs, the limb is in a state of semiflexion, we shall find it difficult to conceive how the head of the bone in passing can encounter any of the fibres of the glutaeus medius or minimus, except it be the most posterior and inferior of them. Mr, Wallace has, in the Transactions of VOL. II. the College of Physicians in Ireland,* given a very minute and valuable account of a case of dislocation of the head of the femur on the dorsum ilii. The history of the case was un- known ; but the state of the parts engaged left no doubt on his mind that it must have been many years since the bone had been dislocated, and from the appearance of the body he con- cluded that the subject was not less than fifty. The glutei muscles were in a state approach- ing to that of atrophy : the posterior edge of the glutaeus medius ran exactly over the head of the femur; the texture of the gluteus mini- mus resembled adeps more than healthy mus- cular fibre. The pyriformis did not extend to the tro- chanter major, but terminated at the distance of some inches from this process, in the new capsule which covered the head of the femur. There was not a trace of the obturator internus, its place having been occupied by a quantity of fat of a peculiarly gristly texture ; the quadratus and gemelli were pale and small, and were bisected by an irregular tendinous line. The direction of these muscles between their points of attachment was more oblique than natural ; the psoas and iliacus were diminished in size, and their line of direction from the brim of the pelvis to their connexion with the lesser tro- chanter was altered, as was also the direction of the triceps, pectinales, and obturator exter- nus, all which were carried upwards above the level of their usual course by the elevation of the upper extremity of the femur on the dorsum ilii. The femoral vessels and nerves having passed under Poupart's ligament, were sunk into a deep fossa, and extended backwards and out- wards until they approached the lesser trochan- ter; they ran more in a serpentine or tortuous course than the corresponding vessels of the opposite limb ; the sciatic nerve was flattened, its direction curved, and its vessels were vari- cose. Its entire structure appeared as if it had been the seat of chronic inflammation. Ligaments. — In this case a very strong liga- mentous fasciculus extended below the anterior and lower part of the llio-pubic eminence and the lesser trochanter; this must have per- formed the function of a check ligament to the motion of eversion, for any attempt at turning the limb outwards rendered this ligament very tense. A thick capsule surrounded the new articulating surface of the ilium, and also the head and neck of the femur; although the inner surface of this was smeared with synovia, it had not the smooth aspect of an original syno- vial membrane. There was imbedded in the capsule a piece of bone of a rounded figure, half an inch in diameter.f There were no re- mains of round ligament. Hones. — The great trochanter was thrown forwards with respect to the head of the bone : the anterior internal and inferior portion of the head of the femur was applied to the dorsum ilii, and there was an articulating surface worn * Vol. V. p. 252. t Mr. W. imagined this to be a portion of the acetabulum. 3 H 818 ABNORMAL CONDITIONS OF THE HIP-JOINT. on the head of the femur, which marked its point of contact with the os innominatum : the articulating surface thus formed on the head of the femur was very slightly convex, about one inch and a half in diameter, smooth, whitish, hard, and polished, though not uniformly so ; for in some parts the bone appeared red and porous ; the remaining portion of the head of the femur was not opposed to bone, but applied to the capsule which surrounded the joint ; the head had lost its natural rounded form, was very irregular, and deprived of its cartilage, but some parts of it were covered by a substance of the nature of ligament. There were several small pits on the head of the femur, but none of them appeared to have been the depression for the attachment of the round ligament. There was an irregular ossific deposit round the lesser trochanter. The surface of the ilium, to which the head of the bone was applied, was elevated half an inch above the level of the surrounding bone, so that this cavity appeared to have been formed upon a plate of bone which had been planted, as it were, on the ilium. The superior and posterior portion of the new acetabulum, or about two-thirds of its whole extent, was smooth and polished, and presented a suitable corresponding surface to receive the head of the femur ; the aspect of the articulating surface on the ilium was backwards, outwards, and up- wards. There was scarcely a vestige of the old acetabulum in its site ; there was a superficial fossa, of a triangular form, filled with a fibrous substance, continuous with a surrounding cel- lular tissue. There was no articular cartilage on any portion of the bones which formed the new joint. There was a deep groove, one inch in depth, formed on the outer side of the ilio- pubic symphysis, for the lodgement of the con- joined tendons of the psoas and iliacus muscles in their passage over the brim of the pelvis to the lesser trochanter. The pelvis, in this case, was much elevated on the side corresponding to the luxation. b. Lupatio/i backwards or towards the ischia- tic notch. — The space which is called the ischiatic notch is bounded above and anteriorly by the ilium, posteriorly by the sacrum, and in- feriorly by the sacro-sciatic ligament (Jig. 323). It is formed forgiving passage to the pyriformis muscle and to the sciatic nerve, as well as to the great arteries, the gluteal, ischiatic, and internal pudendal. Its situation, with respect to the acetabulum in the natural position of the pelvis, is a little above its level, and it is also placed behind it ; when the head of the bone is thrown into this space, it is placed backwards and up- wards with respect to the acetabulum. Therefore though called the dislocation backwards, it is to be remembered that it is a dislocation back- wards and a little upwards. In this dislocation the head of the thigh-bone is placed on the pyriformis muscle, between the edge of the bone which forms the upper part of the ischiatic notch and the sacro-sciatic liga- ments, behind the acetabulum, and a little above the level of the middle of that cavity. Fig. 323. 1, Pyriformis; 2, lesser sacro-sciatic ligament; 3, gemellus superior ; 4, obturator internum ; 5, ge- mellus inferior ; 6, tuber ischii. It is the dislocation most difficult both to detect and to reduce ; to detect, because the length of the limb differs but little, and its po- sition is not much changed as regards the knee and foot, as in the dislocation upwards ; to re- duce, because the head of the bone is placed deep behind the acetabulum, and it therefore requires to be lifted over its edge, as well as to be drawn towards its socket. The signs of this dislocation are, that the limb is about half an inch shorter than the other, but generally not more than half an inch ; that the trochanter major is behind its usual place, but still remains nearly at right an- gles with the ilium, with a slight inclination towards the acetabulum ; the head of the bone is so buried in the ischiatic notch that it cannot be distinctly felt, except in thin persons, and then only by rolling the thigh-bone forwards, as far as the comparatively fixed state of the limb will allow. The knee and the foot are turned inwards, but not so much as in the dis- location upwards, and the toe rests against the ball of the great toe of the other foot. When the patient is standing, the toe touches the ground, but the heel does not quite reach it ; the knee is not so much advanced as in the dislocation on the dorsum ilii, but is still brought a little more forwards than the other, and is slightly bent. The limb is fixed, so that flexion and rotation are in a great degree pre- vented. The following case of dislocation backwards towards the ischiatic notch affords us a good example of this accident. John Magee, set. 54, a strong muscular labourer, was admitted into Jervis-street Infirmary, lOthof November,1831, under my care, in consequence of his having been severely injured in his left hip. He stated that while carrying on his back a sack of pota- toes, (about 3 cwt.) he unfortunately placed his ABNORMAL CONDITIONS OF THE HIP-JOINT. 819 foot upon a round stone, which rolled from under him, and he came down with consider- able violence on his left knee and side ; when raised, he was incapable of walking, and was immediately carried to hospital. The follow- ing morning, on examination, we made the fol- lowing observations : while standing, the body was bent forwards, inclining towards the left or affected side ; the left knee and foot were turned inwards ; the knee somewhat more ad- vanced and higher than the other, half flexed, and the toes were resting on the ball of the great toe of the opposite foot ; posteriorly, the natis was prominent, and its lower fold was obliterated ; the distance between the anterior superior spinous process of the ilium and tro- chanter major was less by one inch than be- tween the same points on the unaffected side ; the head of the bone could not be distinctly felt ; the limb could be drawn inwards across the opposite thigh, but any attempt to move it in the contrary direction was productive of considerable pain ; he complained of much uneasiness in the groin (which was attributed to the tense state of the muscles inserted into the trochanter minor) ; the patient complained greatly of numbness extending along the poste- rior and outer part of the thigh and leg to the foot. The bone was, in this case, easily re- duced, not, however, without the assistance of the pulleys. This dislocation is improperly denominated by some, luxation downwards and backwards. Some surgeons, on the other hand, describe cases of this accident, and yet name them dis- location upwards and backwards on the dor- sum ilii. Of this class, is an interesting ex- ample published by the late Dr. Scott, of the Armagh Infirmary, in the third volume of the Dublin Hospital Reports. The man, the sub- ject of the accident, died thirty-six hours after the injury. Dr. Scott says : — " When the patient was lifted out of bed and placed erect, the limb retained the posture before described ; it was nearly two inches shorter than the other; the knee rested above its fellow ; the toes were turned inwards, and lay above the opposite instep. On viewing the hip, the trochanter was manifestly higher on the maimed side than the other. The hollow naturally formed behind that process had disappeared — the buttock was shorter and rounder, but flaccid ; the head of the bone could not be felt through the glutaei muscles. No effort of the patient could extend the limb, but he had the power of bending it a little towards the abdomen, by making the op- posite leg a fulcrum for the inverted toes to creep upwards upon. The dislocation was re- duced, and he died in thirty-six hours after- wards, in consequence of the injury some of the organs in the abdomen received, at the same time that the hip-joint was dislocated." It is stated, that " on dissecting down to the hip-joint, an extensive extravasation of blood presented itself in the cutaneous cellular membrane, co- vering the trochanter major, and also beneath the fascia lata of the thigh, extending several inches above and below the trochanter. The gluteus magnus being raised from its origin, a considerable extravasation was found in the loose cellular tissue under the gluteus medius. A cavity capable of containing a pullet's egg was also brought into view. This cavity was situated directly where the great sciatic nerve passes under the pyrifbrm muscle; it contained fluid blood ; its boundaries were the pyriformis above, the sciatic nerve before (supposing the body upright), the trochanter major, and insertion of the gluteus medius external and posterior ; the gluteus maximus directly posterior. Here the displaced head of the femur had been lodged. The fleshy substance of the gemelli and quadratus muscles was found torn across. The pyriformis and obturator internus were perfect; the extravasated blood followed the course of the sciatic nerve deep into the thigh ; there was also extravasation between the gluteus medius and minimus muscles. The internal and upper part of the capsular liga- ment of the joint was ruptured; the external portion remained unbroken. On turning the head of the bone out of its socket, the liga- mentum teres was found to have been torn from its insertion into the dimple of the head of the thigh-bone ; the brim of the acetabulum, at its upper part, was fractured to the extent of about one inch ; the fractured portion lay loose and nearly unconnected ; a fracture traversed the acetabulum." In this case it is manifest, from the dissection, that the head of the bone lay beneath even the level of the lower edge of the pyriform muscle, as Dr. Scott states that the boundaries of the cavity (capable of containing a pullet's egg, and rilled with coagulated blood,) which no doubt was the new situation that the head of the dislocated femur for a time rested in, — that the boundaries of this cavity were " the pyriformis above," &c. The dis- section we consider a valuable one, adding something to our knowledge of the anatomical characters of the luxation into the ischiatic notch ; differing, however, in some few particu- lars, from that of Sir A. Cooper, Dr. Scott's, it is to be recollected, was the dissection of a case in which the bone had been only a few hours misplaced. When we analyse the previous symptoms of Dr. Scott's case, we do not, it must be confessed, read the characteristic fea- tures detailed of the dislocation backwards ; still the pain the patient suffered along the course of the sciatic nerve rather pointed the attention to a dislocation on the sciatic notch, than to the ordinary one of dislocation upwards on the dorsum ilii, in which the nerve is not, at least directly, interfered with; and the observation added, that " the head of the bone could not be felt through the glutei muscles," also would lead us to infer that among many of the symptoms this patient laboured under, some were such as would lead us to suspect that the luxation was that backwards towards the sciatic notch, a suspicion that, in the wri- ter's mind, the dissection given by Dr. Scott would fully justify. We suspect, also, that one of the cases 3 H 2 820 ABNORMAL CONDITIONS OF THE HIP-JOINT. published by Mr. Bransby Cooper* as one of dislocation on the dorsum llii, was ra- ther the dislocation we are now considering, namely, the luxation towards the ischiatic notch. Among some of this patient's symp- toms, it is mentioned that the trochanter major was plainly felt behind and a little above the natural situation with respect to the ilium; the head of the bone could be felt neither in the sitting, standing, nor lying posture. Indeed, Mr. B. Cooper himself remarks that, " upon taking into consideration all these diagnostic marks, I was induced to consider the acci- dent a luxation on the dorsum of the ilium ; although the head of the bone was not drawn up so high as usual, as indicated by the slight shortening of the limb ; and the trochanter major was also drawn further backwards than is usual, in the dislocation on the dorsum, so that, perhaps, this might by some surgeons have been described as a dislocation to the ischiatic notch." Mr. Cooper further adds : — " I doubt, however, if this appellation as applied to a cer- tain variety of dislocation of the hip, does not rather mystify than facilitate our diagnosis, for it leads to the supposition that the head of the bone sinks into the osseous hiatus, — a cir- cumstance which could not occur even in the skeleton itself, from the size of the head of the bone, and much less could it happen in the living subject, when this notch is filled up with ligaments, muscles, vessels, and nerves." This respectable surgeon proposes, therefore, to expunge from the classification of dislocations the luxation into the notch, but to consider it only as a variety of the dislocation on the dorsum ilii, distinguishing the one as a luxation upwards, the other backwards, on the dorsum. To this proposition we cannot by any means assent, for we consider that a dislocation back- wards behind the ischium, and to the ischiatic notch which is below the level of the ilium, never can be properly designated a variety of the dislocation on the dorsum ilii, although we might assent to the proposition to consider it a variety of the dislocation backwards. The case as described by Sir A. Cooper, of disloca- tion on the sciatic notch, we are satisfied is to be seen occasionally, though rarely, in the living; and the dissection made by Sir Astley himself, in which he found the head of the bone resting behind the acetabulum on the pyriform muscle, the preparation of which is to be found in the museum of St. Thomas's Hospital, should, we imagine, place the matter beyond dispute. Anatomical characters. — We have, says Sir Astley Cooper, a good specimen in the collec- tion of St. Thomas's Hospital, which I met accidentally in a subject brought for dissection. The original acetabulum is entirely filled with a ligamentous substance, so that the head of the bone could not have been returned into it. The capsular ligament is torn from its connection with the acetabulum at its anterior and posterior junction, but not at its superior and inferior. The ligamentum teres is broken, and an inch of * Guy's Hosp. Repor J, n. 1836. it still adheres to the head of the bone. The head ot the bone rests behind the acetabulum, on the pyriformis muscle, at the edge of the notch above the sacro-sciatic ligaments. The muscle on which it rests is diminished, but there has been no attempt made to form a new bony socket for the head of the os femoris. Fig. 324. Around the head of the thigh-bone a new capsular ligament is formed ; it does not adhere to the articular cartilage of the ball of the bone which it surrounds, but could, when opened, be turned back to the neck of the thigh-bone, so as to leave its head completely exposed. Fig. 324. Luxation in the sciatic notch. Within the new capsular ligament, which is formed of the surrounding cellular membrane, the broken ligamentum teres is found. The trochanter major is rather behind the acetabu- lum, but inclined towards it relatively to the head of the bone. This dislocation, he adds, must have existed, from the appearances of the parts, many years. The adhesions were too strong to have admitted of any reduction, and if reduced, the bone could not have remained in its original socket. c. Luxation upwards and inwards on the pubcs. — This luxation is more easy of detection than any other of the thigh. It happens from a person while walking putting his foot into some unexpected hollow in the ground, and his body at the moment being bent backwards, the head of the bone is thrown forward upon the os pubis. The limb in this species of dislocation is an inch shorter than the unaffected one ; the knee and the foot are turned outward, and * From Sir A. Cooper, pi. iv. on Fractures and Dislocations. ABNORMAL CONDITIONS OF THE HIP-JOINT. 821 cannot be rotated inwards, nor flexed with- out causing acute suffering. The inguinal region is the seat of the principal pains, which however from this point extend along the thigh, and are the consequence of the stretching which the anterior crural nerve necessarily suffers as it is raised up at the neck of the bone. The striking criterion of this dislocation is, that the head of the thigh-bone may be dis- tinctly felt upon the pubes, above the level of Pou part's ligament, and it feels as a hard ball, which is readily perceived to move by bending the thigh-bone. The femoral artery has been usually felt pulsating along the inner side of the head of the bone, but Mr. Smith presented lately to the Pathological Society the cast of a ease of this luxation, in which he had noticed that the femoral artery ran in a tortuous manner directly across the head of the dislo- cated bone. The great trochanter is drawn upwards and forwards, so as to be situated in the trajet of a line which would pass from the anterior infe- rior spine of the ilium, downwards and for- wards. In a case of a dislocation of this spe- cies which was left a long time unreduced, the motion of the knee backwards and forwards was fully twelve inches. The following case was admitted into Jervis Street Hospital, under the care of Mr. O'Keilly, during the time I was one of the surgeons to that institution, and as it seemed to me the best marked case of the kind I had ever witnessed, I beg here to lay it before the reader from my case-book. Case. — P. Bryan, a powerful man, aged 37, was admitted into Jervis Street Infirmary, Uec. 4, 1828. He was intoxicated when the accident which produced the luxation occurred, and consequently was unable to give any idea as to how the injury was produced. As the patient lay on his back in bed the affected limb appeared to lie parallel to its fellow, but then there was an eversion of the whole limb, and the foot of course turned out- wards. One circumstance particularly caught our observation, viz. the preternatural ly arched appearance which the upper third of the shaft of the femur presented ; the adductor muscles were full and prominent; there was an unusual prominence underneath Poupart's ligament; the anterior superior spinous process appeared retired. On making more minute examination it was found that the eversion of the foot was perma- nent, and we were surprised to find that there was but little difference between the length of both limbs ; certainly the injured one was little more than half-an-inch shorter than the sound one. A considerable depression existed where formerly the trochanter major lay ; this process of bone was very evident, and could be readily felt about two inches below and somewhat anterior to the anterior superior spinous pro- cess of the ilium, and about the same distance internal to it a well-marked prominence in the inguinal region shewed the new situation which the head of the femur occupied ; along its inner side were seen and felt the pulsations of the femoral artery. On communicating a motion of rotation outwards, the head of the bone could be easily felt under the soft parts ; the nates was flattened ; the femur was but little moveable with respect to the pelvis, and any attempt to draw the thigh backwards caused great pain to the patient : to flex it was impossible. A motion of rotation outwards could be communicated to the dislocated femur, but no rotation inwards was permitted. Ad- duction of the limb was admissible, even to permit the knees to touch. When the patient stood up, he naturally threw his weight on the sound limb, and the affected one was flexed slightly at the knee, and the heel touched the inside of the opposite foot, as in the " first position" of dancers. The reduction of the dislocation was effected in the ordinary method ; indeed the rules laid down by Sir. A. Cooper were fully adopted, and in due time succeeded. Anatomical characters of this luxation.— Sir A. Cooper gives us an account of the dis- section he made of one of these luxations of the femur on the pubes, which had been a long time unreduced; he found the original ace- tabulum partially filled by bone, and in part occupied by the trochanter major, and both are much altered in form ; the capsular ligament is extensively lacerated, and the ligamentum teres broken. The head of the thigh-bone had torn up Poupart's ligament, so as to be admitted between it and the pubes (jig. 325). The head Fig. 325. Luxation on the pubes.* and neck of the bone were thrown into a position under the iliacus interims and psoas muscles, the tendons of which, in passing to their in- sertion over the neck of the bone, were elevated by it and put on the stretch. The crural nerve passed on the fore-part of the neck of the bone, * From Sir A. Cooper, loc. cit. plate v. 822 ABNORMAL CONDITIONS OF THE HIP-JOINT. upon the iliacus internus and psoas muscles. The head and neck of the thigh-bone are flattened, and much changed in their form. Upon the pubes a new acetabulum is formed for the neck of the thigh-bone, for the head of the bone is above the level of the pubes. The new acetabulum extended upon each side of the neck of the bone, so as to lock it in a cer- tain direction upon the pubes. Poupart's ligament confines it on the fore-part ; on the inner side of the neck of the bone passed the artery and vein, so that the head of the bone was seated between the crural sheath, and the anterior and inferior spinous process of the ilium. d. Luxation downwards and inwards into the foramen ovale. — When the femur is in a forced state of abduction, if violence be in any man- ner applied so as still further to exaggerate this movement, the head of the femur having pre- viously glided from above downwards in the acetabulum to its utmost, applies itself to the interior of the capsular ligament, which it stretches; if the force be continued the capsule soon gives way, and the head of the femur, bursting through the rent, is dislocated and lodged in front of the obturator foramen. The symptoms by which we recognize this accident are very well marked, as the limb in this dislocation is two inches longer than the other. The body is bent forwards owing to the psoas and iliacus internus muscles being put upon the stretch (fig. 326). The knee is consi- derably advanced ; if the body be erect it is widely separated from the other, and cannot be brought without great difficulty towards the middle line or made to touch the other knee, owing to the extension of the glutaei and pyriform muscles. The foot, though widely separated from the other, is generally neither turned outwards nor inwards, although it varies a little in this respect in different instances, but the position of the foot does not in this case mark the accident. The adductor muscles are elongated and form a round prominent line which extends from the pubes to the middle of the thigh. The foot and the knee are turned outwards because the adductor and the other muscles which execute the movement of rotation outwards are on the stretch and elongated. The thigh cannot be adducted, and when we wish to communicate this movement to the limb the patient feels severe pains because of the tension which the glutaei and rotators outwards suffer. The reason of the flexion of the leg is two-fold ; first to relax the hamstring muscles which are put upon the stretch by the dislocation, and to establish an approach to an equality in the length of the limb. When we examine closely the injured hip, we notice a considerable hollow at the upper and outer part of the thigh where the great trochanter is normally seen projecting, and a depression is noticed below the centre of Pou- part's ligament. The head of the dislocated bone can be felt occasionally at the inner and outer parts of the thigh towards the perineum. The position of the head of the bone is below Fig. 326. Luxation into the foramen ovale. the acetabulum and a little anterior to it. The bent position of the body, the separated knees, and the increased length of the limb constitute the striking and characteristic features of this rare accident. That excellent practical surgeon, Mr. Hey of Leeds, had not during a period of public and private practice for thirty-eight years seen a case of this accident of luxation downwards and inwards into the foramen ovale, until in the year 1797 three patients were brought into the infirmary of Leeds. In one of the best marked examples of this accident the dislocated thigh appeared much thicker at the superior part than the other; the adductor muscles, it appears, were upon the stretch, and the inguinal hollow we can collect was effaced (perhaps by the tension of the skin and effusion). Mr. Hey says, the head of the bone could not be dis- tinctly felt through the muscles ; yet, from the appearance and the touch, it was sufficiently evident that the head of the bone lay upon the great foramen of the os innominatum. It seemed probable that it had passed so far from the acetabulum as to be in contact with the descending part of the os pubis. There was in this case a considerable hollow at the upper and outer part of the thigh where the great trochanter is usually felt projecting. The following case of dislocation of the ABNORMAL CONDITIONS OF THE HIP-JOINT. 823 femur into the foramen ovale I saw in Steevens's Hospital, and my friend Dr. Osbrey has obliged me with his notes of the case, which were as follows : — Michael Murphy, at. 21, a labourer, ad- mitted June 4th, 1834, under Mr. Colles with dislocation of the head of the femur into the foramen ovale. He stands with his entire weight upon the sound side, the left thigh flexed on the pelvis, his knee bent, and toes turned out and resting on the ground, from which the heel is raised ; the thigh is abducted so that he cannot bring his knees nearer than within five inches of each other, when standing up not within nine, and at this time his toes are thirteen inches asunder; the thigh is wasted, and he cannot support any weight on the limb. When asked to walk without support he places his hand firmly on the knee, and bears his weight on the arm and leg without throwing any of it on the thigh. His pelvis is lower on the injured side, and there is a slight curvature of the spine, the convexity to the same side, in conse- quence of which there is great apparent length- ening of the limb. The real difference when measured from the symphysis pubis to the point of the inner ankle is two inches and a half, but there is little or no difference when measured from the spine of the ilium ; and when the measurement is taken from the tuber ischii the dislocated limb is two inches longer than its fellow. There is considerable deformity about the joint; a deep hollow exists immediately below the anterior spine of the ilium, through which the sartorius runs obliquely, joining a prominent ridge when the muscle is in action. The prominence of the trochanter is altogether lost, and that process can be with difficulty felt. The fold of the buttock is completely obliterated, and there is a fullness towards the upper and back part of the thigh, caused by the head of the bone, which can be felt through the adductor muscles, and seems to be situated further inwards than is usually described in this accident. He states that he received the injury five weeks ago; he was thrown down on his right side obliquely against a wall, by a horse running away with a cart, and the wheel of the cart passed over his left hip above the trochanter ; lie felt great pain at the time which was chiefly referred to the inside of the knee. He was carried home and nothing was done for him for a fortnight, when he went to a hospital, where several attempts were made at reduction ; all, however, failed, and after re- maining there a fortnight longer he came up to Dublin in the state above described. On the 12th of June two attempts to reduce the bone failed altogether, and the man returned to the country. Anatomical characters. — It seems probable that the head of the dislocated femur passes so much forwards and inwards from the acetabu- lum as to be in contact with the inner margin of the thyroid foramen, where this foramen is completed by the rami of the ischium and Dubes. The convexity of the great trochanter has the acetabulum behind it, and the lesser trochanter is placed immediately external and anterior to the tuberosity of the ischium. The ligamentum teres and lower part of the capsular ligament have been torn through, and the head of the bone " become situated in the interior and inner part of the thigh upon the obturator externus muscle." We have, says Sir Astley Cooper, an ex- cellent specimen of this accident in the collec- tion of St. Thomas's Hospital, which I dissected many years ago. The head of the thigh-bone was found resting on the foramen ovale, but the obturator externus muscle was completely absorbed, as well as the ligament naturally occupying the foramen now entirely filled by bone. Around the foramen ovale bony matter was deposited so as to form a deep cup, in which the head of the thigh-bone was inclosed, but in such a manner as to allow considerable motion ; and the cup thus formed surrounded the neck of the thigh-bone without touching it, and so enclosed its head that it could not be removed from its new socket without breaking its edges. The inner side of this new cup was extremely smooth, not having the least ossified projection at any part to impede the motion of the head of the bone, which was only restrained by the muscles from extensive movements. The original acetabulum was half filled by- bone, so that it could not have received the ball of the thigh-bone if it had been put back into its natural situation (fig. 327). The head of the thigh-bone was very little altered, its articular Fig. 327. Luxation into the foramen ovale. * From Sir A. Cooper, pi. ii. 824 ABNORMAL CONDITIONS OF THE HIP-JOINT. cartilage still remained, the ligamentum teres was entirely broken, and the capsular ligament partially torn through. The pectinalis muscle and adductor brevis had been lacerated, but were united by tendon. The psoas muscle and iliacus interims, the glutafi and pyriformis, were all upon the stretch. e. Cases of unusual dislocations. — In Guy's Hospital Reports we find the account of two cases of dislocation of the head of the femur upwards and outwards towards the anterior superior spinous process of the ilium. In the first of these cases, detailed by Mr. Morgan, the affected leg (the left) was short- ened to the extent of at least two inches, the foot was excessively everted, so much so as almost to give the toes a direction backwards. The injured limb had a tendency to cross that of the opposite side, so that the heel was thrown over the instep of the opposite foot ; neverthe- less when the feet were placed side by side, they remained in that position. The limb was susceptible of all the natural motions to some extent, with the exception of rotation, but the man complained of great pain when under ex- amination. The projection of the trochanter major was entirely lost, whilst the luxated head of the bone might be felt under Poupart's liga- ment, just below and to the inner side of the anterior superior spinous process of the ilium, and it apparently lay between the anterior and inferior spinous process of the ilium, and the junction of this last bone with the pubes; it thus rested upon the brim of the pelvis, and projected upwards towards the abdomen ; the femoral artery was not displaced in this dislo- cation, but could be traced taking its usual course, and consequently situated to the inner side of the displaced bone. In this case a speedy reduction of the dislo- cated bone was effected, but in the second case I have alluded to, the bone was left unreduced for years. We are indebted for the publication of the whole case, accompanied with the dis- section, to Mr. Bransby Cooper, who tells us that the preparation which illustrates the acci- dent the patient suffered from, was presented to Sir Astley Cooper, by his friend Mr. Old- know of Nottingham, and the bones are pre- served in the museum of Guy's Hospital. The subject of the accident was a lunatic, aged 28, and as far as we can learn from the detail of the case given, his symptoms were very much those which Mr. Morgan's patient presented before the dislocation was reduced.* Upon dissection it was found that the old acetabulum was deprived of articular cartilage, and was in part filled up by bony deposit, so as to be rendered wholly unfit for the reception of the head of the femur. The new acetabulum was nearly directly above the original cavity, and was bounded on the outside by the two anterior spinous processes, and on the inside by the line of junction of the ilium and the hori- zontal branch of the pubes, that is to say, by the ileo-pubal eminence. The form of the new * Guy's Hospital Reports, January, 1836, p. 99. cavity for the reception of the head of the femur was very like the natural acetabulum, but not quite of equal dimensions ; it is protected above by a growth of bone which overlapped the head of the femur, and must have formed the princi- pal point of support of that bone. The inferior part of the new acetabulum was the most defi- cient. The trochanter major sunk partly into the old acetabulum, and polished points on both the old and new acetabulum indicated where the head of the femur and trochanter major played in the various motions this imperfect joint enjoyed. We are not informed how the muscles were altered from their normal state, but may infer that most of them were more or less atrophied ; it is probable, however, that both the obturator externus and internus were put much upon the stretch, and retained the bone more or less downwards. It would have been interesting to have learned the precise situation of the rectus femoris, tensor vaginae, and sartorius, psoas, and iliacus, but we can easily imagine that the latter were much shortened, and that they were raised up from the pubes by the dislocated bone, the tendon of the rectus must have been thrown outwards over the rest of the femur and trochanter major. The head of the femur was altered from its original figure, so as to be adapted to the new acetabulum, portions of it being diminished where it did not come in con- tact with the new cavity, so that its spheroidal figure was lost. The periosteum of the femur, as well as of the new acetabulum, assisted in forming the new capsular ligament. The arti- cular cartilage of the head of the femur has been absorbed, and the same porcelain-like concretion, as is seen in the acetabulum, is provided at corresponding points. From the form of the articulating surfaces, and the fixed position of the femur, both at the head and the trochanter major, it will be observed that no other motion than flexion could be permitted, and even that motion, from the closeness of the attachment at the trochanter, but to a limited extent. Luxation of the head of the femur down- wards and backwards. — This luxation may be considered as a very rare accident. When the last edition of Sir A. Cooper's work on Fractures and Luxations was published, the baronet had not seen such an accident, as he remarked, " it is to be remembered that there is no such accident as a dislocation of the hip downwards and backwards." Dupuytren says, " I have only twice or thrice seen this luxation downwards and backwards. The limb was then twisted inwards, a little elongated, and it was impossible to adjust it to its ordinary place and position, without reducing the luxation, which once accomplished, the dis- placement did not a second time recur." My friend Mr. Wormald, assistant-surgeon to St. Bartholomew's Hospital, has published an account of an accident of this kind in the Medical Gazette, June 28, 1837, and the preparation, which shews the relative position of the head of the dislocated bone, &c. and the acetabulum, HYPEREMIA AND ANEMIA. 825 is preserved in the museum of the hospital. Fig. 328. Fig. 328. Dislocation downwards and backwards. B, obturator internus ; C, trochanter major; D, the acetabulum; E, obturator externus ; V, sciatic nerve; I, shaft of the femur. " A maniac who eluded the vigilance of his keepers, leaped from a third story window. Besides dislocating his thigh, he received other injuries, of which he died in about an hour. " On examining the dislocated limb, it was found considerably shortened and inverted, forming about half a right angle with the body, the shaft of the femur crossing the symphysis pubis was fixed immoveably in this situation ; as the patient was sinking, no attempt was made at reduction. " Twelve hours after the death of the patient I commenced the dissection, by reflecting the gluteus maximus, when I found some of the fibres of the glutoeus medius and minimus rup- tured at their posterior edge. The pyriformis and gemelli were also partially torn, but those portions of the tendon of the obturator internus which pass through the lesser ischiatic notch were drawn out, and separated from their con- nexion with the muscular fibres ; the head of the femur presented itself through a rent of the capsule, opposite to the upper part of the tuber ischii above the quadratus, so that the great sciatic nerve was somewhat displaced and pressed against the tuber ischii. " In this case there was no difficulty in de- tecting the nature of the injury, as, besides the symptoms already described, the head of the femur could be felt resting on the tuber ischii, covered by the outer edge of the gluteus maxi- mus. " If this patient had been in a condition to attempt reduction of the dislocation by fixing the pelvis, and employing extension in the direction of the shaft of the bone, at the same time everting the limb, the head of the femur would have been brought opposite the rent in the capsule, and would have been in all pro- bability replaced in the acetabulum without greater difficulty than is usually experienced." ( Robert Adams.) HYPEREMIA and ANiEMlA, (v^, super ; a,, negative ; and onyLoc, sanguis) (in morbid anatomy). These are terms employed to denote opposite conditions of the various membranous or parenchymatous textures of the body as regards the quantity of blood contained in their bloodvessels ; the former, as its deriva- tion denotes, indicating a superabundant sup- ply of blood, the latter a deficiency of that fluid. They are useful terms to the anatomist, inasmuch as they express simply the state of a texture, without any theory being involved respecting the cause or origin of that state. It ought always to be the first business of the anatomist to observe carefully the actual con- dition of the parts submitted to his examination; this having been done, he should search dili- gently for some cause, mechanical, chemical, or vital, which will satisfactorily account for the phenomena. All vascular textures, it is obvious, are liable to these conditions; and it is equally evident that the relative frequency of their occurrence in different textures will coincide with the natural facility of the flow of blood to or from them, as well as the quantity of blood con- tained in them in the normal state. Thus the lung or the spleen is favourable for the forma- tion of hyperemia, as well from the large supply of blood in each as from the free com- munication between their respective arterial and venous systems, and between the ramifications of vessels of the same kind. A bleached slate of the same organs may be taken as a good example of the opposite con- dition, or anaemia; but the most complete anosmia is, of course, to be found in organs or tissues which, in the natural state, contain but a small quantity of blood. It is important to notice that hyperemia may occur independently of disease and altogether as a cadaveric phenomenon, and there is no mistake more frequently committed by the incautious observer than that of attributing to the influence of a morbid process during life appearances which simply result from the ordinary physical laws which death has allowed to exert full sway over the tissues. Indeed, it is only since anatomists have ceased to regard every instance of an unduly injected tissue as a diseased one, that valuable practical conclu- sions have been drawn from post-mortem obser- vations. We may pronounce hyperemia not to be mor- bid, when it is found to occupy only the most dependent parts of organs, the blood having deserted the vessels of the more elevated parts. At every post-mcrtem examination we have abundant examples of hyperemia of this kind ; if the body have been laid on the back, as is usually the case, the whole of the skin of that region is largely injected with blood ; the sub- cutaneous cellular tissue is in a similar condi- tion, and the adjacent muscles more or less so 826 HYPERTROPHY AND ATROPHY. likewise. The blood in these cases is chiefly contained in capillaries and veins, the ramifica- tions of which will be found fully injected. The dependent parts of all the vascular tissues and organs of a body thus placed, exhibit similar appearances. The scalp on the occiput, the posterior lobes of the brain, and the cerebellum are much more injected than the anterior parts of the same textures. The pos- terior parts of the lungs, of the stomach and intestines, of the spleen, liver, and kidneys exhibit the same state of vascular congestion. That this results altogether from position and the blood in the vessels obeying the universal law of gravitation, may be clearly proved by reversing the position of the body, when after a little time the blood will desert the former dependent but now elevated parts, and those portions of the texture which before were almost devoid of blood from their elevated position, now have their vessels filled with it. When hyperemia results from a mechanical obstacle to the circulation, it is not accumulated at one part of an organ or viscus, but all parts appear equally gorged with the blood. In certain diseased states of the heart and liver, the intestinal canal presents an example of this general hyperemia, owing to the mechanical obstacle to the free circulation of the blood in the right heart. The circumference of the intestine is every where reddened by the blood accumulated in its capillaries. Andral, by whom of late years the term hy- peremia itself was brought into use in morbid anatomy, gives the following varieties of it. 1. Active or sthenic hyperemia, denoting the state indicated by the ordinary expression acute inflammation. 2. Passive or asthenic, resulting from diminished tone in the capil- lary vessels. 3. Mechanical, from an obstacle to the venous circulation. 4. Cadaveric or post-mortem, being the result of those physical and chemical laws to which all inorganic matter is subject, and to which all organized bodies are also subjected when the vital spark has ceased to animate them.* This last variety, moreover, he subdivides into two genera. First gemts, hyperemia produced at the mo- ment of death. — Cause; the contractility of tissue which resides in the small arteries, con- tinuing to act after the heart has ceased to beat. Second genus, hyperemia produced at a certain period after death. This genus comprehends the following species :■ — 1. Hyperemia by hy- postasis or dependent position. 2. Hyperemia by transudation of the blood or of some of its component parts through the parietes of its vessels. 3. Hyperemia by chemical affinities. Anaemia, a term long in use to express a general exsangueous and cachectic condition of the body, is also applied to a local state of exsangueousness. Any cause which would impede or cut off the wonted supply of blood to a part will occasion this condition in it; the diminution in the calibre of the principal artery of an organ, from mechanical pressure or disease * Path. Anat. by Townsend, vol. i. p. 15. in the vessel, or a depressed state of the nervous influence. Hyperemia of one organ may give rise to anaemia of another, the former as it were attracting the blood away from the latter. The general condition of anosmia is not un- frequently brought under the physician's notice either as the result of some excessive and long- continued hemorrhage or of some deranged state of general nutrition, giving rise to a deterio- ration in the quality of the blood, or a general deficiency in the powers of the nervous in- fluence. The surface of the body is pale, the mucous membranes, as far as they can be seen, partake of the same exsangueous state, the secretions are defective and vitiated, the tone of the muscular and vascular systems is con- siderably diminished, and this state may go on without any specific morbid change in any organ, beyond its participation in the general scanty supply of the blood, or it may co-exist with an organic disease, which, although it may have been at first the result of the primary exciting cause of the anaemia, now serves to increase it, or offers the greatest impediment to its removal. (R. B. Todd.) HYPERTROPHYandATROPHY, (vve?, super, a,,priv., and T^(pu,nutrio),{m morbid ana- tomy). When any organ or tissue has acquired a certain increase of developement, without any manifest alteration of its natural structure, it is said to be in the state of hypertrophy — the increase being due to a greater activity of the nutritive process in the part affected. A familiar example of hypertrophy, although not morbid, is afforded by the augmentation which muscular fibre acquires in consequence of increased action. If the biceps muscle of one arm be actively exercised, while that of the other does not undergo any considerable degree of action, the former acquires a great increase of size, it becomes denser and firmer, and manifests the physical and vital phenomena of the muscular tissue with more than ordinary energy. There is no texture in the body which does not occasionally exhibit evidence of the hyper- trophous condition. The circumstances which favour its production are an abundant and a free afflux of blood to the part, an energetic nervous influence and an increased demand upon the organ, or increased exercise if it be muscular; and indeed these are the almost in- variable conditions under which hypertrophy is manifested. The heart becomes hypertrophous under an exalted nervous influence, or from a necessarily increased exercise from the effort to overcome some obstacle to the free circulation of the blood through its cavities ; one kidney acquires a great increase of size if the other one be incapable of performing its function. It may be said that the liver is in a state of hypertrophy in the foetus in utero, for it has a larger supply of blood than in extra-uterine life, and the lungs have not as yet begun to share with it in the office of decarbonizing the ILIAC ARTERIES. 827 venous blood. The bladder also, like the heart, acquires an enormous developement of its muscular coat, when any obstacle obstructs the free flow of the urine from it. The physi- cal condition, then, of a hypertrophous organ differs but in degree from that of the part in its normal state. There are, in general, in- crease of^size, of weight, and of consistence, with more or less alteration of shape consequent upon the former ; an increased supply of blood, and a consequent heightening of colour. To judge therefore how far an organ has experi- enced hypertrophy, the anatomist must care- fully compare its present condition, as regards size, weight, colour, consistence, and supply of blood, with the average state of the parts in health. Atrophy is not only opposite in its nature to hypertrophy, but it results from causes of an entirely opposite kind. A defective state in the nutritive process is its immediate cause : — the affected part shows manifest signs of wast- ing ; it diminishes in size and in consistence ; it loses its colour from the deficient supply of blood ; its physical and vital properties are manifestly altered, and are fully developed. When the wasting has gone to its greatest ex- tent, the natural texture disappears, or is so altered as to present but few of the characters of its normal condition. As frequent exercise and use favour the production of hypertrophy, so on the other hand disuse and inactivity give rise to atrophy. Neither the vascular nor the nervous systems of such parts afford their wonted supplies ; and those physical characters which are present in hypertrophy in an exalted condition, are in atrophy either absent altoge- ther, or but feebly developed. The muscles of paralytic limbs, the hearts of old persons which have been overloaded with fat, the diminution in size and almost total disappear- ance of the thymus gland in the adult, the diminution of the left lobe of the liver in extra- uterine life, the obliteration and conversion into a fibrous cord of certain disused venous and arterial canals, and the wasting of the optic nerve where the eye is destroyed, are examples of atrophy of every day's occurrence. (See the articles on the morbid anatomy of the different textures and organs.) (R. B. Todd.) ILIAC ARTERIES* (so called from their situation in the iliac regions) are three upon each side of the body, viz. the primitive iliac, the internal and the external iliacs ; they are the main arteries of the pelvis and the lower ex- tremity. Primitive iliac arteries (common iliacs, * But little dissection is necessary to display the iliac arteries ; the abdominal wall having been di- vided and thrown bads, the peritoneum may be detached from without inward, along with the con- tained viscus, from the iliac fossa, which having been done to a sufficient extent, care being at the same time taken to leave uninjured the spermatic vessels the vas deferens and the ureter, the iliac arteries will be exposed still covered by their imme- diate investment. urterice iliac a primitive, s. communes, s. pelvi- crurules; Fr. Artiresiliuques primitives; Germ. Gemeinschaftliche Huft-pntsadern,) are two, one on each side : they are vessels of great size, from three-eighths to four-eighths of an inch in diameter, but short, their length varying from one and a half to two and a half or three-quarters of an inch, the arteries being longer or shorter, according to the height at which the aorta divides. They arise from the termination of the aorta, their origin corresponding, as a mean point, to the in- terval between the bodies of the fourth and fifth lumbar vertebras, and somewhat to the left of the middle line of the vertebral column ; the exact height of their origin, however, varies considerably, ranging in ordi- nary between the bodies of the third and fifth vertebrae ; but they have been found to arise very near to the diaphragm.*" From their origin they descend, and at the same time in- cline outward and backward, forming with each other an acute angle, but more so in the male than in the female subject, because of the greater width of the pelvis in the latter, until they reach a point ranging between the body of the fifth lumbar vertebra and the sacro-iliac articulation, f where they terminate by dividing into the internal and external iliacs. The point of reference usually assigned for this division is the sacro-iliac articulation ; but this appears not to be strictly correct, the exact point varying as well on the opposite sides of the same as in different subjects; for the most part the division takes place between the two points, which have been mentioned ; at times nearer to one, at times to the other, and according to Velpeau, it usually occurs nearer to the spine upon the right than upon the left side ; hence, according to the same authority, the right external iliac artery is longer than the left, and were it pos- sible to ascertain these diversities of origin during life, advantage would result therefrom, inasmuch as the prospect of success in high ligature of the external iliac must be influenced by the height of its origin, and the difficulty of reaching the primitive or the internal iliacs must be increased in the same proportion. These views appear well-founded ; the division of the primitive iliac rarely takes place so far outward as the sacro-iliac articulation, and for the most part it is nearer to the body of the vertebra, or higher upon the right than the left side, and therefore the external iliac of that side is usually the longer, but this disposition is not constant; the division of the ri^ht primitive artery is not always higher than that of the left, nor conse- quently the right external longer, and therefore while probability is in favour of the conclusion which the facts stated indicate, it cannot be absolutely relied upon. The primitive iliac arteries are of the same size, and nearly the same length ; the right, however, is considered for the most part some- what the longer, because of the situation of the * Velpeau, who cites Petsche on the authority of J. F. Meckel, t Bogros. 828 ILIAC ARTERIES. aorta upon the left side of the spine; Velpeau, however, seems to question the existence of any difference in the length of the two vessels, inas- much as the right divides generally nearer to the spine than the left, the inclination of their origin to the left being thus compensated, but to what- ever extent this view may hold good, it is by no means strictly correct ; in fact the length of the arteries, whether comparative or absolute, is far from regular; nor is the preponderance, when present, always upon the same side ; the opinion generally entertained is probably correct, the light artery being in the majority of instances somewhat longer than the left ; but the writer has found the left the longer of the two, and the same disposition has been observed by J. F. Meckel; this is, however, an unusual disposition. The relations of the arteries are simple. During their descent they are situate in front of the bodies of the lumbar vertebras, with the intervening fibro-cartilages, of one, two, or more of these bones, according to the height at which the arteries arise, and also of the lateral part of the base of the sacrum ; they are both covered upon three sides by the peritoneum, viz. in front and laterally, the membrane descending upon them from the root of the mesentery; the mesentery itself also and the small intestines are placed before them, and the latter overlap them upon either side. Farther, they are in front of the superior branches of the middle sacral artery and of the sympathetic nerve. That of the right side at its outset is placed before the left primitive iliac vein, which it crosses at its junction with the cava,'and par- tially before the commencement of the cava itself ; during its course it is in front of the right primitive vein, at first only partially, but, as it proceeds, covering it to a greater extent, until at its termination it is directly before it. External to both, but on a plane posterior to them, are the psoae muscles, the left artery how- ever being nearer to the muscle than the right, between which and the psoas the right primitive vein and the cava intervene, being at the same time posterior to it. Internal to both at their origin is the middle sacral artery ; on the left side the left primitive vein lies along the inside of the artery, but on a plane behind it. Anteriorly the arteries are crossed at their termination by the corresponding ureter, that duct being interposed between the peritoneum and the vessel, but more adherent to the former. The relation of the ureter to the iliac arteries is not uniform, either on opposite sides or in different subjects ; the bifurcation of the pri- mitive iliac may be assumed as the mean point of reference for its transit, the duct descending into the pelvis between the external and internal iliacs, and before the internal ; but its precise relation will depend upon the height at which the bifurcation takes place and the side of the body to which it belongs, and hence it very frequently, if not usually, crosses the external iliac upon the right and the termination of the internal on the left. The artery and vein, the relations of which differ remarkably upon the two sides, the vein beirfg external upon the right and internal upon the left, and upon both posterior, are enclosed within a condensed cellular investment, pro- longed upward upon the aorta and downward upon the secondary iliacs ; upon the primitive vessels it is so thin that it may at times seem absent; but, as it descends, it increases in thickness, and acquires upon the external iliacs considerable strength. The primitive iliac arteries ordinarily give only minute branches to the adjoining parts, viz. the ureter, the peritoneum, the. vein, lym- phatic glands and cellular structure ; but occa- sionally they have been found to give off the ilio-lumbar artery, and more rarely a renal or spermatic artery.* Although, according to the view usually taken, the primitive iliac terminates by dividing into internal and external, yet in many instances it will be found that the primitive and external iliacs appear as one vessel giving off the internal from its posterior side, and nearly at right angles, while in the foetus the reverse seems the case, the primitive and internal being continuous and rather giving off the external. Internal iliac artery. f ( Arteria iliuca interna, s. hypogastrica, s. umbilicalis ; Fr. artere iliaque interne, ou hypogastrique ; Germ. Becken-pulsader oder innere Huft-pulsader.) This artery from the time of birth supplies the viscera and parietes of the pelvis, both externally and internally ; prior to that epoch it is the channel through which the blood is trans- mitted from the body of the foetus to the placenta, whence it may then be termed with propriety the " placental artery," since such is its chief office, the other distribution being of inconsiderable extent, and the divisions of the artery intended for it small in proportion ; hence the vessel presents a remarkable contrast at the two periods of life, in the foetus being a large and long vessel extending from the ter- mination of the aorta, for, as has been before stated, it seems at that time the continuation of the primitive iliac artery, to the placenta giving off in its course small branches to the viscera and parietes of the pelvis, while in after life the placental artery has disappeared, and in its stead is found a short trunk of considerable size, — the commencement of the placental artery as it had been — from which arise nume- rous vessels for the pelvis and its viscera. The internal iliac arises from the posterior side of the primitive iliac artery,} between the body of the last lumbar vertebra or the sacro- vertebral angle, and the sacro-iliac articulation, but generally higher upon the right side than the left ; it descends into the pelvis in front of * J. F. Meckel. t The internal iliac and its branches should be examined first with the pelvis complete, the peri- toneum and viscera being detached trom its lateral wall, and the latter alternately empty and distended ; afterward a section of the pelvis may be made through the symphysis pubis and the middle of the sacrum, preserving the viscera with their attach- ments to one side ; but this should not be done until after the dissection of the perineum. | See primitive iliac for point and mo^e of division. ILIAC ARTERIES. 829 the sacro-iliac articulation or of the lateral part of the sacrum, as it may be, inclining backward and outward, and describing a curve concave forward, until it reaches the superior part of the great sciatic notch, where it usually divides ; this however is by no means uniform, the point of its division ranging between the brim of the pelvis and the notch. The internal iliac is an artery of great size, but in the adult smaller than the external ; its course is somewhat tor- tuous and short, from one and a half to two and a half inches. During its descent the artery is placed before the lumbo-sacral nerve, on the left side before the primitive iliac vein, and on both before the sacro-iliac articulation or the lateral part of the sacrum. Before it are in the male the bladder or its lateral connections, in the female the uterus and its broad fold of peritoneum ; ex- ternally the artery corresponds to the internal iliac and the commencement of the primitive iliac veins, to the inside of the psoas magnus muscle, to the brim of the pelvis, to the obtu- rator nerve, which it crosses nearly at right angles, to the lumbo-sacral and first of the anterior branches of the sacral nerves, and to the superior attachment of the pyriformis muscle : the ilio-lumbar artery is also external to the internal iliac, between it and the wall of the pelvis. Internal to it are the peritoneum, the rectum with its mesentery, and the superior hemorrhoidal vessels, (these parts being nearer to the artery upon the left than the right,) and the small intestine when in the pelvis. The external iliac vessels are above, before, and external to the internal.* In the foetus the condition of the internal iliac differs remarkably from that which it presents in after life; in it both in size and direction this artery appears the continuation of the primitive trunk, exceeding the external as much as afterward it is exceeded by it. It is the channel which conveys the blood to the placenta, and it is generally entitled the " hypogastric or umbilical artery ;" " placental'' would certainly be preferable. It passes from the primitive iliac or rather from the aorta, for there the primitive iliac appears only the com- mencement of the placental artery, downward and at first outward as far as the sacro-iliac articulation, where it gives off the external iliac artery, then forward to the side of the bladder, descending but little into the pelvis and at the same time giving off pelvic branches; it next changes its direction and ascends in- clining inward toward the umbilicus, at first by the side of the bladder and then in the anterior abdominal wall, between the peritoneum and the rectus muscle or its sheath, and on either side of the urachus ; thus forming a curve convex downward through the concavity of which pass the vas deferens or round ligament before, the ureter posteriorly and the rectum, the extremity of the ilium and the appendages of the uterus in the mean space. Having reached the umbilicus the artery escapes through it from the body of the foetus and is conducted * 'Hiis is to be understood to refer to the recum- bent posture ; in the erect posture the external arc not superior to the internal vessels. by the umbilical cord to the placenta ; during their transit to the placenta the arteries at the very early periods of utero-gestation, are straight, but afterwards, in proportion as the develope- ment advances, they become tortuous, and are twined round the umbilical placental vein, whence the length of the arteries exceeds that of the cord which varies from one to two feet. At the placenta the two arteries are connected by a considerable anastomosis, and divide into numerous branches, which subdivide minutely in the lobes of that structure, the ramifications of the several lobes being distinct from each other; ordinarily the two vessels are distinct until they approach the placenta, but they have been found to unite into a single one before escaping from the abdomen of the foetus.* The placental arteries give off within the body of the foetus branches similar in number and destination with those of the primitive iliac of the adult, but in a rudimental condition; between the summit of the bladder and the umbilicus however they do not furnish branches, and hence, the circulation through them be- tween these points ceasing at birth, they be- come obliterated to the same extent and connected into impervious cords, known by the name of umbilical ligaments ; these hold the same course and relation with the original vessels, and are less distinct in proportion to the age of the subject; they are covered upon their abdominal aspect by the peritoneum, which is reflected upon them to a greater or less extent according to the subject, and thereby forms triangular falciform folds, the base of which is below in the iliac fossa, and the apex above toward the umbilicus, and in the free edge of which the ligament is contained. At a point intermediate to the brim of the pelvis and the upper part of the sacro-sciatic notch the internal iliac artery divides into branches ; these are numerous, amounting altogether in the male to nine, and in the female to eleven ; but in their mode of origin they vary very much, arising sometimes separately, sometimes by common trunks, but for the most part from two, into which the iliac divides ; these are an anterior one giving off the hemorrhoidal, the umbilical, the vesical, the uterine, the vaginal, the sciatic and internal pudic, and a posterior, from which arise the ilio-lumbar, the lateral sacral, the obturator and the gluteal. Another diversity in the mode of their origin is that of the obturator from the epigastric or external iliac. The branches of the internal iliac are arranged either into four sets, viz. posterior, anterior, internal, and inferior,! or into two, internal and external,]; the former distributed within, the latter without the pelvis ; the latter seems the more simple division, and is the one which will be adopted in this article. The internal branches are in the male five, in the female seven ; they are as follow — 1. The iliolumbar artery varies in size and ori- gin ; for the most part it arises from the posterior * Cloquet. t Cloquet. X Harrison 830 ILIAC ARTERIES. division of the internal iliac, at times from the iliac itself; at times from the gluteal, occa- sionally from the primitive iliac, and frequently by a trunk common to it and the lateral sacral ; from its origin, which is somewhat below the base of the sacrum, it runs upward, outward, and backward toward the iliac fossa, passes in front of the sacro-iliac articulation and the lumbo-sacral nerve and external to the obturator nerve; having surmounted the outlet of the pelvis it passes behind the psoas muscle, the external iliac vessels and the anterior crural nerve, and emerges from behind them at the superior and internal part of the fossa, where it divides. As the artery emerges from the pelvis it gives off' a branch which descends along the brim, gives small branches to the inside of the psoas, and finally anastomoses with a branch from the epigastric artery ; while concealed by the psoas it gives branches to it and the iliacus internus. Finally it divides into two sets of branches, superior or ascending, and external or transverse ; the former ascend beneath the psoas, supply it, the iliacus and the quadratus lumborum, send a branch into the vertebral canal through one of the inferior intervertebral foramina, and finally communicate with the inferior lumbar arteries. The external set pass outward into the iliac fossa, and are distin- guished into two, a superficial and deep ; the former run across the iliacus muscle, superficial to it and beneath the iliac fascia, supply the muscle and anastomose freely with corres- ponding branches from the circumflex branch of the external iliac artery : the superior of the superficial branches runs round the crest of the ilium within its inner edge, as it proceeds it gives branches downward to the iliacus and upward to the quadratus lumborum, the trans- versalis and oblique muscles, some of which turn over the crest and communicate with branches of the gluteal artery ; finally it ends in a direct and free anastomosis with the ultimate branch of the circumflex artery, the fossa having thus an artificial circle formed around it in- ternally, between these branches and the original iliacs. The branches of the deep set pass into the substance of the iliacus muscle, and between it and the bone, and are distributed to the muscle, the periosteum, and the bone, one of them entering the ilium through the canal to be observed at the bottom of the fossa ; their deep branches also communicate with the circumflex iliac, the gluteal and the external circumflex femoral arteries. Sometimes there are two ilio-lumbar arteries. 2. The lateral sacral artery may be either single or double, and arises either from the posterior division of the iliac, from the iliac itself on its inner side, from the gluteal, or the sciatic, and frequently in common with the ilio-lumbar : it runs downward, and inward in front of the lateral part of the sacrum, the sacral nerves at their exit from the anterior sacral foramina, and the pyriform muscle external to the middle sacral artery and the sympathetic nerve ; it descends to the extremity of the sacrum and then anastomoses with the middle sacral and the artery of the other side ; at tunes instead of terminating thus it enters the sacral canal through the third or fourth foramen and is distributed internally. Its branches are dis- tinguished into two sets, an anterior or internal and a posterior or external. The former are distributed to the sacral nerves within the pelvis, to the pyriform muscle, to the pelvic cellular tissue and glands, to the levator ani muscle and to the sacrum. The posterior are the larger, they are usually four, but at times more numerous, two branches sometimes taking the same course ; they pass backward along the sacral nerves, through the sacral foramina, into the canal, and then divide into two, of which one is distributed within the canal to the nerves and their ganglia, to the membranes and the sacrum ; the other escapes backward through the posterior sacral foramen, and is distributed upon the back of the sacrum in the sacro-vertebral channel, anastomosing with the adjoining vessels. 3. The yniddle hemorrhoidal artery is some- times wanting, its place being supplied by branches from the other divisions of the iliac; it is of about the same size as the previous arteries, and varies very much in its source, arising from the anterior division of the iliac, from that vessel itself or from the pudic, the sciatic or lateral sacral arteries, it runs down- ward, forward, and inward along the side and front of the rectum, at first between the intes- tine and the levator ani, and then between it and the fundus of the bladder in man and the vagina in the female, and divides into branches, of which the greater part are distributed to the rectum, anastomosing with the branches of the superior hemorrhoidal from above and with those of the inferior hemorrhoidal from below ; others are distributed to the fundus of the bladder, the prostate and vesiculas in man, and to the vagina in the female. 4. The vesical arteries are subject to great variety ; they are numerous and smaller than the last described : they are distinguished by Harrison into three sets, inferior, middle, and superior ; the inferior set consists of those branches given to the fundus of the bladder by the middle hemorrhoidal, pudic, and sciatic arteries ; the superior, furnished by the um- bilical, are two or more in number, and are distributed to the superior region of the bladder, but the middle is a single vessel larger than the others, and given off by the iliac artery, though frequently arising from some of its branches, particularly the umbilical : it is en- titled by Chaussier " vesico-prostatique :" it passes downward and inward to the fundus of the bladder, and then divides into branches distributed to the bladder, and in the male also to the prostate, the vesiculas and neck of the bladder. 5. The umbilical artery. In the adult sub- ject a small arterial canal usually from an inch and a half to two inches and a half long ex- tends from the termination of the internal iliac, or from one of its branches to the superior lateral part of the bladder; there it is continued with, or seems to have attached to it superiorly the umbilical ligament, the artery appearing ILIAC ARTERIES. rather to be continuous with the last branch arising from it. A variable number of branches arise from it ; these are generally the superior vesical, at times the vaginal or the uterine ; and according to their number and size its size varies ; it is not destined to any part, but only gives rise to these branches, being in reality not a branch of the iliac but so much of the vessel, originally the umbilical or placental, as inter- venes between the origin of the great branches and the point at which it becomes impervious, which remains open because of the origin of the vesical arteries, &c. from it, but is thus re- duced in size because of their minuteness. 6. The uterine artery arises either from the anterior division of the iliac, or from the pudic, or at times from the umbilical ; it runs forward, inward, and somewhat downward, until it reaches the superior lateral part of the vagina, and entering the broad peritoneal fold of the uterus it ascends in it along the lateral region of the uterus in a very tortuous manner, its tortuosity increasing as it proceeds. As it as- cends, it gives off a considerable number of transverse branches, which attach themselves to both surfaces of the organ, penetrate its substance, and supply it with blood, anasto- mosing, at the same time, freely with those from the other side. When it has reached the attachment of the ligament of the ovary, the artery anastomoses with the spermatic artery. Before the artery attaches itself to the uterus, it gives a considerable branch to the vagina, which descends along it to a greater or less extent and is distributed to both its aspects. Branches also go from it to the Fallopian tube, the round ligament, and the ligament of the ovary, and likewise communicate with branches of the spermatic. The uterine artery in the unimpregnated con- dition of the uterus is a small vessel, little, if at all, larger than the hemorrhoidal or vesical arteries, but during impregnation, and the more so in proportion as that state advances, it un- dergoes a remarkable change, becoming greatly enlarged, so much so as to equal or exceed in size any of the other branches of the internal iliac ; and at the same time assuming a most tortuous arrangement as well in its branches as in its trunk. 7. The vaginal artery arises also, when pre- sent, from the anterior division of the iliac, or from the pudic, the uterine, the umbilical, or hemorrhoidal ; it is therefore very irregular and often absent, its place being supplied by branches from others. It runs forward and downward along the side of the vagina, dis- tributing branches to it, and also to the bladder and rectum. At the extremity of the vagina it terminates in the external genital organs, and communicates with the branches of the pudic artery. The external branches of the internal iliac artery are four, viz. 1 . The obturator or thyroid arteri/, ( artere sous-pubio-femorale, Chauss.) is a vessel of con- siderable size, inferior only to the gluteal, pu- dic, and sciatic branches, and about equal to the epigastric artery, but irregular in that as well as in other respects. It arises most fre- quently from the posterior division of the internal iliac or from the iliac itself imme- diately before its division ; it runs forward and somewhat downward along the lateral wall of the pelvis toward the superior posterior part of the subpubic or thyroid foramen, through which it escapes from the pelvis into the supe- rior internal part of the thigh. The course of the vessel may be divided into three parts : — 1st, that within the pelvis ; 2d, that in the sub- pubic canal ; 3d, that in the thigh. Within the pelvis the artery is nearly parallel to the brim of the pelvis, or ilio-pectineal line, and from one-half to three-fourths of an inch be- neath it, it holds a similar relation to the exter- nal iliac vessels, which are above the line and from which it is distant from three-fourths of an inch to one and one-fourth. It is accompanied by the obturator vein and nerve, and is placed between them, the nerve being above and the vein beneath it. It is situate within the pelvic fascia; externally it rests against this fascia above the origin of the levator ani muscle, and separated by it from the internal obturator muscle ; internally it corresponds in front to the side of the bladder to an extent proportioned to the degree to which that viscus may be dis- tended, and is connected to it by cellular sub- stance ; posteriorly it corresponds to the peri- toneum of the pelvis, the ureter, and at times to the anterior division of the iliac artery or some of its other branches. In this part of its course it gives off a branch which ascends- to the iliacus and psoas, brandies to the obtura- tor internus, to the lymphatic glands of the pelvis and the bladder; lastly, as it approaches the subpubic foramen it gives an important branch, which ascends posterior to the pubis, distributes small branches as it proceeds, and ends in an anastomosis with a branch, which descends from the epigastric artery. Harrison has occasionally found a considerable branch given off in this situation, which passed to the side of the prostate and the perineum, supply- ing the place of deficient branches of the pudic artery.- In escaping from the pelvis the artery is contained in an oblique canal leading inward and forward. This canal, the subpubic, is bounded superiorly and externally by the pu- bis, which presents on the under surface of its horizontal ramus an oblique channel, by which the roof of the canal is formed ; inferiorly and internally it is bounded by the margins of the obturator muscles and ligament; toward the pelvis it presents a defined aperture circum- scribed above by the pubis and below by the pelvic fascia, the attachment of which to the bone is interrupted at the part at which the artery passes out, and which describing a curve beneath the vessels, between its points of attachment at either side contributes thus to form a rounded aperture through which they escape without perforating the fascia ; a thin prolongation of the fascia is detached from it beneath the vessels into the canal. Hernia occasionally protrudes through this canal, and the artery has been found by Cooper behind 832 ILIAC ARTERIES. the neck of the sac and rather to its inner side. While within the canal the artery gives outward a considerable branch — its posterior or exter- nal, or it might be with propriety called its thyroid branch — which runs downward and backward along the external margin of the thyroid foramen, between the two obturator muscles, giving them branches, and at times altogether consumed in them. Having reached the tuberosity of the ischium, it gives branches to the quadratus and adductor magnus muscles, to the upper attachments of the flexors of the leg, and to the ilio-femoral articulation, into which it sometimes sends through the cotyloid notch a branch more frequently supplied by the internal circumflex (femoral) artery ; it also sends another round the thyroid foramen, which meets a similar branch from the obtura- tor. It anastomoses with the internal circum- flex and the sciatic arteries. At its entrance into the thigh, the obturator artery is situate above and before the obturator externus muscle, and behind the pectinalis, which with some of the fibres of the adductor longus must be divided in order to expose the vessel. It descends be- tween the pectinalis, the long and short adduc- tors, and is distributed to them, the adductor magnus, the gracilis, and the integuments upon the upper and inner part of the thigh. It gives also a branch, which runs round the margin of the thyroid foramen, and meets the branch already described from its thyroid branch. The artery anastomoses freely with the internal cir- cumflex artery. The obturator artery presents many varieties as to its source, of which some are deserving of particular attention. According to J. F. Meckel its ordinary source is the posterior division of the internal iliac, either immediately or by a trunk common to it and the ilio-lumbar, but at least once in ten times it arises from another source. The next most frequent is the internal iliac itself above and before its division ; then the anterior division of the iliac ; occasionally the external iliac, and sometimes the femoral, even so low as two inches from Poupart's liga- ment. The most frequent variety, and which according to the same authority is as common as the origin from the internal iliac itself, is that the artery arises from the epigastric, or from a trunk common to both. Sometimes it has a double origin, being formed by the union of two branches of equal size, one from the epi- gastric, and the other from the internal iliac, and at times it has a different source upon op- posite sides. In every case the destination of the artery is the same ; it runs to the inner aperture of the subpubic canal, in order to escape to the thigh, and in so doing it holds a very intimate relation to the internal femoral ring in those instances in which it proceeds either from the epigastric or from the femoral. When it arises from the epigastric, it runs obliquely downward, backward, and inward, above the crural arch, toward the superior aperture of the pelvis, then entering the pelvis posterior to the pubis it turns downward be- neath it, and gains the subpubic foramen. During its descent into the pelvis the artery superiorly is covered by the peritoneum, and inferiorly corresponds to Poupart's ligament and the internal femoral ring, but the side of the ring, at which it may be placed, varies in different instances. When the common trunk from which the epigastric and obturator arise is short, the obturator lies close to the inside of the external iliac vein and then is situate on the outer side of the ring, while when the com- mon trunk is long the artery is more remote from the vein, coasts along the base of Gimber- nat's ligament, and thus runs obliquely across the front and inner side of the aperture. Ac- cording to the case, therefore, will be the rela- tion of the artery to the neck of femoral hernia ; in the former it will be situate external and posterior to it, in the latter anterior and inter- nal. When hernia descends not only into the lym- phatic compartment of the sheath, but, as has been observed by Burns, also into that belong- ing to the vein, thus forming a double protru- sion, the artery may, if the common trunk be short, be situate external to the neck of the former and internal to that of the latter. The comparative frequency of this mode of origin of the obturator artery has been diffe- rently estimated. According to Monro it oc- curs in one of twenty cases ; Velpeau coincides in this opinion; Lawrence states it to be once in ten ; J. F. Meckel considers it to be as frequent as that from the internal iliac ; and according to the observations of Cloquet the proportion of instances in 250 subjects in which the artery was found to arise from the epigastric, whether on one or both sides, was one in three, and that of all the origins from the epigastric to all those from other sources was still greater, about I..24. A more important question is the pro- portion borne by those instances in which the obturator arising from the epigastric is situate on the inside of the neck of the hernia, to the total number of such cases, or to that of cases of femoral hernia requiring operation, for it is obviously with it that the operator is concerned. Cooper has not met the artery on the inside of the hernia, though in six of twenty-one cases he found the origin from the epigastric ; and Lawrence states that the proportion of the for- mer cases does not exceed one in eight or ten, and therefore that the obturator artery would be endangered only once in eighty or one hun- dred operations. When the obturator arises from the femoral artery, which Cloquet found in six of 250 subjects, it ascends into the abdomen beneath the crural arch, along the pectinalis muscle and internal to the femoral vein, and in femoral hernia is found behind the sac. We are indebted to J. F. Meckel for solving the apparent irregularity of these origins of the» obturator, and reducing them to a mere varia- tion of the normal condition ; the obturator, as has been stated, is normally connected with the epigastric by an anastomotic branch, and hence may be considered as having two origins, an anterior and a posterior, a disposition the reality of which is more manifest at the earlier periods of life, and according as the one or the other ILIAC ARTERIES. 833 may be deficient or more developed, the obtu- rator will be derived principally or altogether from the internal iliac or from the epigastric ; when both are equally so it will present the double origin. 2. The gluteal artery, denominated also posterior iliac, is the largest branch of the internal iliac, and arises from, or is the conti- nuation of the posterior division of that vessel ; it runs downward, backward, and outward, until it reaches the superior part of the great sciatic notch ; it then changes the direction of its course, and making a turn passes directly out- Ward between the lumbo-sacral and the anterior branch of the first sacral nerves, and escapes from the pelvis through the upper part of the notch above the pyriformis muscle, and accom- panied by the superior gluteal nerve. As soon as the artery has escaped from within the pelvis and gained its external aspect, it divides into branches. The trunk of this artery, as it is the largest, so is it the shortest of the branches of the iliac; within the pelvis it corresponds ex* ternally to the lumbo-sacral nerve, internally to the rectum, and inferiorly to the first sacral nerve and the pyriformis ; it gives small branches to the rectum, the pyriformis, and the surrounding cellular structure ; at times it also gives off the llio-lumbar, the lateral sacral, or the obturator. At its exit posteriorly from the pelvis it is situate between the adjoining margins of the pyriformis and the gluteus minimus, and it is covered by the gluteus maximus. The branches into which it divides after its escape are two, a superficial and deep one. The first passes outward and upward between the glutei maximus and medius, and divides into numerous branches, which are distributed to these muscles, particularly to the maximus; many of them descend in its substance toward its insertion, and there meet branches of the circumflex (femoral) and sciatic arteries; others pass through the muscle, become superficial, and supply the integument and subcutaneous fat; others again pass onward, traverse the attachment of the gluteus maximus to the sa- crum, and are distributed to the muscles and integuments of the posterior sacral region. The second, the deep branch, passes outward, upward, and forward, between the glutei medius and minimus muscles toward the superior anterior spinous process of the ilium in an arched course around the attachment of the gluteus minimus. As it proceeds it gives off numerous branches upward from its convexity and downward from its concavity ; the former are distributed to the gluteus medius; the lat- ter are chiefly two, of which one runs forward and downward toward the anterior part of the great trochanter between the two muscles, gives branches to both, and finally throws itself into the gluteus medius near the trochanter, and is consumed in it : it communicates freely with the external circumflex artery. The other runs downward and forward toward the back of the trochanter, lies for some way upon the gluteus minimus, or over the interval between it and the pyriformis, gives branches to both muscles, VOL. IF. and then gains the surface of the oS innomina- tum by traversing the gluteus or by passing between it and the pyriformis, pursues its course upon the bone, to which it gives an artery, above the llio-femoral articulation, to the capsule of which it also gives branches, and approaching the anterior inferior spinous process of the ilium it terminates in supplying the gluteus minimus, and anastomosing with the external circumflex artery. The deep division of the gluteal artery hav- ing run round the line of attachment of the gluteus minimus, and reached the superior anterior spinous process, terminates in an anas- tomosis with the circumflex iliac, the ilio-lumbar, and the external circumflex arteries; branches also turn over the crest of the ilium, and so communicate with the iliolumbar. The deep division, also, furnishes a nutritious artery to the ilium, the canal for which is to be seen on the dorsum of the bone. The branches of the gluteal artery are numerous and large ; in order to expose them the gluteus maximus having been dissected clean may be detached from the femur and raised toward the sacrum, when the branches may be displayed running in every direction as from an axis. The situation of the gluteal artery external to the pelvis permits the trunk of the vessel to be secured ; the gluteus maximus being the only muscle by which it is covered, it may be exposed by the division of that muscle; the situation of the artery may be first determined " by drawing a line from the posterior spinous process of the ilium to the miclspace between the tuberosity of the ischium and the great trochanter; if we divide this line into three, we shall find the gluteal artery emerging from the pelvis at the juncture of its upper and middle thirds."* The ligature of this artery in case of aneurism has been very much superseded in favour of that of the inter- nal or even of the primitive iliac, the latter of which has been tied by Guthrie for aneurism of the gluteal artery ; the propriety of this pro- ceeding, however, may be questioned ; the ligature of either the internal or the primitive iliac must be regarded a more serious operation than that of the gluteal, and the latter has proved so efficacious in the many instances in which it has been had recourse to, that, while it is practicable, the other can be hardly justi- fiable. 3. 'The ischiatic artery arises from the ante- rior division of the internal iliac, which, after having given off its internal branches, divides into two, of which the posterior and larger is the ischiatic ; it is the second in size of the branches of the iliac, being smaller than the gluteal; but in the adult it appears, for the most part, in- direction the continuation of the original vessel ; its course within the pelvis is long; it descends, at the same time inclining forward, and forming a curve convex backward, toward the inferior part of the great sciatic notch, and escapps through it from the pelvis superior to the sacro-sciatic ligaments and infe- rior to the pyrifoimis muscle; it then descends * Harrison. 3 I 834 ILIAC ARTERIES. behind the ischium between its tuberosity and the great trochanter of the femur, and gives off as it descends numerous branches distributed in the superior posterior region of the thigh. Within the pelvis the artery is situate internal to the sacral nerves and the pyriformis muscle, external to the rectum and the peritoneum, in front of the sacrum, the nerves and the attach- ments of the pyriformis, and posterior and ex- ternal to the pudic artery; in escaping from the cavity it passes between the pyriformis and ischio-coccygeus muscles, and is accompanied by the pudic artery, to which it holds the same relation as before, but is closer to it, and by the sciatic nerve ; within the pelvis it is internal and anterior to the sacral plexus, but as it goes out it passes between its branches, and thus becomes posterior to the nerve. Without the pelvis the ischiatic artery corre- sponds in front to the spinous process of the ischium, the gemelli, with the obturator inter- nus muscles, and the quadratus ; posteriorly, it is covered by the gluteus maximus and the inte- guments ; it is situate at first behind the sciatic nerve, but as it descends it becomes internal to the nerve, the distance between them increasing at the same time. While behind the spinous process of the ischium the ischiatic artery is external to the pudic artery, and more super- ficial, i.e. still posterior; butasthe pudic passes to the inside of the tuberosity of the bone, while the ischiatic runs on its outside, the two vessels immediately separate and cease to be related. Within the pelvis the ischiatic artery gives some irregular and small branches to the rec- tum, the bladder, the uterus, the vagina, the cellular tissue, the pyriformis and levator mus- cles ; at times it is considered as giving off also the pudic, the hemorrhoidal, or obturator arteries. The branches which it furnishes ex- ternal to the pelvis are numerous ; among them are distinguished the following : — 1. The coccy- geal branch, of considerable size, runs down- ward and inward toward the coccyx, across the pudic artery and posterior to it, passes through the great sacro-sciatic ligament, and divides into branches, which are distributed to the ligament, to the gluteus, the coccygeus, and levator ani muscles, to the posterior aspect of the sacrum and coccyx, and to the fat and integument ; its branches communicate with those of the pudic. 2. A considerable branch or set of branches, which run outward and downward toward the back of the great trochanter upon the internal obturator, gemelli, and quadratus muscles, sup- ply them with branches, and anastomose with the circumflex (femoral) arteries. 3. A branch or branches to the inferior part of the gluteus maximus, prolonged through it to its insertion, and then meeting the circumflex and perforating arteries. 4. A branch or branches, which attach themselves to the sciatic nerve, naturally of small size, but regular, and remarkable for the extraordinary change they undergo after the interruption of the main artery of the thigh; they arise about the tuberosity of the ischium, and descend along the nerve giving it branches, and communicating with branches from the perforating arteries, which also attach them- selves to the nerve, whereby a chain of auasto- moses is established along it, which, when the main channel has been interrupted, becomes amazingly enlarged and forms, as it were, one remarkably tortuous vessel along the entire length of the nerve. 6. A very considerable branch, the termination of the artery, distri- buted to the upper extremity of the flexors of the leg, the biceps, &c. and of the adductor muscles ; the ramifications of which communi- cate with the perforating and internal circumflex arteries. The ischiatic artery is circumstanced external to the pelvis so similarly to the gluteal, that, if necessary, it might be exposed during life by a similar operation ; for a mpthod of determining its situation prior to operation, the reader is re- ferred to the description of the pudic artery. 4. The internal pudic artery arises from the anterior division of the internal iliac, which for the most part, after having given off its other branches, divides into the ischiatic and the pudic ; the height at which the division takes place is uncertain ; at times it does not occur until the trunk has descended to the sciatic notch, or even escaped from the pelvis. The pudic artery is smaller than the sciatic; it passes downward, forward, and inward, until it reaches the inferior part of the great sciatic notch, through which it escapes from within the pelvis in company with the ischiatic artery, the pudic, and sciatic nerves ; having escaped from the pelvis it crosses the extremity of the spinous process of the ischium and the attach- ment of the anterior sacro-sciatic ligament, and returns into the cavity through the anterior notch, accompanied by the pudic nerve ; having re-entered the pelvis, it then runs forward, in- ward, and downward internal to the tuberosity of the ischium, until it reaches its anterior ex- tremity, whence it continues its course upward along the inside of the rami of the ischium and pubis toward the arch of the pubis, and beneath the latter finally divides ; the course of the artery, therefore, forms a considerable curve convex downward and backward, during which the vessel is contained within the pelvis at its commencement and its termination, and is without the cavity during the intermediate part. Its course is thence divided into three stages, during two of which it is within, and in the third without the cavity. The first stage of the artery's course, through- out which it is contained in the pelvis, extends from its origin to the lower part of the posterior sacro-sciatic notch, through which it escapes from the cavity ; it is of variable length, in con- sequence of the variable height at which the vessel arises. The relations of the artery during this stage are posteriorly and externally the sacral nerves, the pyriform muscle, and the sacrum ; internally the peritoneum and the rectum ; it is posterior and external to the fun- dus of the bladder and the vesiculae seminales, and anterior and internal to the ischiatic artery ; previous to its exit it sometimes passes between the sacral nerves before forming the plexus. It goes out from the pelvis below the pyriformis and above the spinous process of the ischium ILIAC ARTERIES. 835 and the anterior sacro-sciatic ligament, passing between the pyriformis and the ischio-coccygeus muscles, and having the ischiatic artery and sciatic nerve both external and posterior to it. Its second stage is situate without the pelvis ; it is usually its shortest one, lasting only while the artery is crossing the extremity of the spinous process of the ischium, and not exceed- ing an inch in length ; it is here situate behind and above the spinous process and the anterior or lesser sciatic ligament ; it is covered poste- riorly by the superior edge of the posterior liga- ment and by the gluteus maximus muscle ; it is internal to both the ischiatic artery and sciatic nerve, and it is crossed posteriorly by the coccygean branch of the former. The third stage of the artery is its longest and most important one ; during it the vessel is situate within the skeleton of the pelvis, though not within the pelvis, in the ordinary sense of the phrase, i. e. within its visceral ca- vity, being excluded therefrom by the struc- tures which form its floor; it lies along the inside of the tuberosity of the ischium and the rami of the ischium and pubis, and its course and relations being different at the posterior and an- terior parts of the stage, they may with advan- tage be considered separately. In the posterior part, or as far forward as the anterior extremity of the tuberosity or the base of the triangular ligament of the perinaeum, the artery descends ; in the anterior it ascends; in the posterior it is situate in the outer wall of the space which in- tervenes between the inside of the tuberosity of the ischium and the rectum — the ischiorectal space. This space is cuneiform, its base below, toward the surface ; its apex above, toward the pelvis ; its inner wall is formed by the levator ani and the dense thin expansion by which the mus- cle is covered externally or inferiorly, its outer by the obturator fascia attached inferiorly to the edge of the great sacro-sciatic ligament and of its falciform process, and by the obturator muscle : the space is occupied by a mass of adipose cel- lular structure, traversed by some branches of the pudic vessels and nerves. In a canal in the obturator fascia the artery is contained through the posterior part of the third stage ; by some it is maintained to be between the fascia and the muscle, in a sort of canal formed inter- nally by the fascia, externally by the muscle and tuberosity, and inferiorly by the great sciatic ligament ; but this is not correct ; the vessel being in the fascia, and not external to it ; the line of its course is convex downward, about an inch and a half from the under Surface of the tuberosity of the ischium at its most de^- pending part, and from two to two and a half inches from the surface, this distance varying of course according to the condition of the sub- ject ; the line approaches the margin of the ramus or the spinous process, thence forward or backward. In the anterior part of the stage the vessel is enclosed in the triangular ligament along its attachment to the bone; consequently, it is separated from the surface by the superfi- cial stratum of this structure first, in the second place by the eras penis, covered by the ischio- cavernous muscle, and behind it by the trans* versus perinei muscle ; and lastly, by the super- ficial structures of the perineum. As the artery proceeds it becomes more superficial, and finally emerges from the triangular ligament, beneath the subpubic ligament, as the dorsal artery of the penis. It is in its third stage that the pudic artery is exposed to danger in the lateral operation of lithotomy ; it may be wounded in either of the two steps of dividing the urethra and prostate or the subsequent division of the superficial structures : in the former case, the danger of the accident will be greatest when the section is effected with the scalpel or gorget, and in pro- portion to the width of the blade, and the de* gree to which the cutting edge may be directed outward, will the clanger be enhanced ; in the second, the risk will be alike with all cutting instruments, and will be determined by the width of the blade, the attention paid to a pro- per degree of lateralization, the manner in which the instrument is made to effect a divi^ sion of the parts, and the extent of the section. The branches of the pudic artery are numerous, and may be conveniently arranged according to the stage of its course, in which they are given off. In its first, before its exit from the pelvis, it gives branches to the bladder, the rectum, the vesiculae, prostate, vagina, and uterus ; it also frequently furnishes the middle hemor- rhoidal. In its second stage, while external to the pelvis, it gives branches to the gluteus, the pyri' formis, the obturator and gemelli muscles, the sacro-sciatic ligament, the ischium, and sacrum ; they anastomose with the ischiatic, the gluteal, and internal circumflex arteries. Those which arise in its third stage are the most important. 1. The artery gives, while on the inside of the tuberosity of the ischium, branches which are distinguished into external and internal ; the former are small, and go to the adipose structure beneath the tuberosity, to the attachment of the biceps, to the obturator intern us, and the integuments : the internal are larger ; they come through the obturator fascia, run inward toward the anus, and are distributed to the adipose cellular structure of the ischio- rectal space, to the levator and sphincter ani, to the extremity of the rectum, and the margin of the anus; they anastomose with branches of the middle hemorrhoidal artery and with those of the other side : they are variable in number, being one, two, or three, and are denominated " external hemorrhoidal ;" they are liable to be divided in operations in the vicinity of the anus, e. g. in the superficial incision in the lateral operation or in operation for fistula ; they are, however, so small that they seldom give trouble, either ceasing to bleed spontane- ously, or being commanded by brief compress sion. 2. The perineal artery. — At a short distance from the base of the triangular ligament the pudic gives off a branch of considerable size and length, by many regarded as one of its ultimate branches ; the pudic, according to them, terminating by dividing into two branches, an inferior, " the perineal," and a superior 3 I 2 83G ILIAC ARTERIES. The perineal artery comes through the obtu- rator fascia, and descends to the perineum, pos- terior to the transverse muscle, though at tunes before it; when it has got below the muscle it changes its direction, and runs forward, up- ward, and inward, superficial to the triangular ligament, toward the root of the scrotum; at this part of its course it is situate along the outer side of the interval which separates the cms penis and the corpus spongiosum urethra?, internal and parallel to the eras, and covered by a superficial lamina of the fascia of the peri- neum, a deeper layer of which intervenes be- tween it and the muscles of the crus and bulb and the triangular ligament ; as it proceeds it gives the following branches : 1. outward, one to the integument and subcutaneous structure beneath the anterior part of the tuberosity of the ischium ; 2. inward, one which runs to the interval between the front of the rectum and the bulb of the corpus spongiosum, superficial and parallel to the transverse muscle ; it sup- plies the integument and subcutaneous struc- ture of the perineum, and the common inser- tion of the superficial sphincter, the transverse muscle, the bulbo-cavernous and the levator ani in front of the rectum. This branch is at times furnished by the pudic itself ; it is denominated by some " the proper perineal," by others " the transverse perineal." 3. A branch to the bulbo- cavernous ; 4. one to the ischio-cavernous mus- cles. The perineal artery having reached the back of the scrotum sends long branches into the subcutaneous structure and integument of that part, and entering the septum scroti, terminates in it as the " artery of the septum." In the female, the ultimate branches of the artery are distributed to the labia majora. The perineal artery, from its superficial situa- tion, is exposed to be divided on many occa- sions; in lateral lithotomy it may be cut, but for the most part it escapes, its course being external to the line of incision ; some of its branches, however, cannot escape, the trans- verse perineal particularly must, as a matter of course, be divided. Having given off the peri- neal artery, the pudic pursues its course, en- closed in the triangular ligament, along the rami of the ischium and pubis, toward the arch of the pubis ; arrived under cover of the crus penis, it gives off a considerable branch, des- tined principally for the urethra and the corpus spongiosum, and denominated hence by Chaus- sier " urethro-bulbaire," by Harrison "arteria corporis bulbosi vel spongiosi urethra," but by Boyer and Cloquet " artere transverse ;" it is short, runs transversely inward, enclosed in the triangular ligament about a quarter of an inch from its base, but nearer to it externally than internally; at the bulb it divides into two parts, of which one, the smaller, is distributed to the ante-prostatic gland ; the other enters the bulb and ramifies through its vascular struc- ture, being prolonged through it as far as the glans, supplying at the same time the mem- brane of the urethra and its lacuna? ; a branch from it passes into the corpus cavernosum, and anastomoses with the artery of that structure. In the female, the branch corresponding to this is distributed to the vascular plexus which sur- rounds the orifice of the vagina. The artery of the bulb is one of much prac- tical importance ; it is liable to be wounded in lithotomy in the act of opening the urethra; this accident is incurred when the canal is opened too high, i. e. too near to the arch of the pubis, or too much from the side rather than from beneath, and in either case is pretty certain to occur ; the proceeding by which to avoid both the artery and the bulb itself, is to cut into the urethra as far back, i. e. from the surface, and as far from the arch as the gui- dance of the staff will assure the operator to be safe, the point of the knife being directed as much from below as the interference of the bulb and the lateral line of incision will permit; further, it is the design of the operator to open the canal in the membranous portion and be- hind the bulb; and in order to effect this, the incision should be made as near as may be to the base of the triangular ligament, or, if possi- ble, behind it. If divided, the artery of the bulb may be tied, though not without some difficulty ; it is prevented from retracting by being enc'osed in the triangular ligament, but it is situate deep; its distance from the anterior surface of the ramus of the pubis being about three-fourths of an inch ; its shortness as well as its being concealed by the crus penis and by the bulb with their muscles, and being in the superior angle of the wound, must also increase the difficulty of securing it. The pudic artery having reached the base of the subpubic ligament divides into its two final branches, the artery of the corpus caverno- sum and the dorsal artery of the penis. 3. The artery of the corpus cavernosum arises from the pudic between the crus penis and the ramus of the pubis and immediately enters the crus obliquely ; it is prolonged through the vascular tissue of the corpus cavernosum to its extremity, distributing branches to either side, and communicating with that of the other. For the peculiar distribution of the arteries of the corpus cavernosum and spongiosum, accord- ing to Miiller, see the article EhectileTissue. 4. The dorsal artery of the penis, which ap- pears indirection the continuation of the original vessel, comes through the triangular ligament and ascends in front of the subpubic ligament through the angle formed by the crura penis at their junction ; having surmounted the crus it attaches itself to the dorsal aspect of the penis and runs forward upon it on either side of the suspensory ligament parallel to the artery of the other side, and contained together with it, the dorsal vein, and nerves, in the groove formed by the apposition of the crura, internal to the nerve and external to the vein; it is prolonged to the anterior extremity of the corpus cavernosum, where it breaks up into branches, which uniting with those of the other form an arterial zone behind the corona glandis, and sinking into the glans are distributed to its tissue. During their course along the dorsum of the penis the arteries are tortuous, communicate ILIAC ARTERIES. frequently, are covered not only by the skin and subcutaneous cellular structure, but also by a dense filamentary expansion, or fascia, which invests the penis beneath them, and they give branches to those structures as also to the fibrous membrane of the corpus cavernosum, and finally to the prepuce. The dorsal artery is at times furnished by the obturator, or the external pudic artery. Beside the varieties of origin which have been mentioned, the pudic presents some im- portant varieties in its course. It has been found by Burns in four instances, " instead of passing out of the pelvis between the sacro-sciatic ligaments to attach itself to the lateral and inferior part of the bladder, and to traverse the upper segment of the prostate gland in its course to the ramus of the ischium." Another variety is described by Harrison, in which the proper trunk of the pudic is found unusually small, and the dorsal artery of the penis arises originally and separately from the internal iliac, 'runs along the side of the bladder and prostate gland, and escapes from the pelvis along with the dorsal vein of the penis beneath the arch of the pubis. The latter dis- position, mutatis mutandis, has been found by Tiedemann in the female as well as m the male, and is figured in his thirtieth plate. It is described by Winslow as the normal arrange- ment, only thataccording to him the vessel, which takes this unusual course, arises sometimes from the common pudic, at others from the iliac. Haller questions the occurrence of this disposition, but describes another, in which the inferior vesical artery arising from the middle hemorrhoidal is continued on the dorsum of the prostate into the dorsal artery of the penis, given, as in ordinary, from the pudic. Among the varieties of the arterial system few possess greater interest than these, inas- much as no foresight or skill can guard against the untoward accidents which attend their presence in lithotomy ; their possibility forbids a section of the prostate upward ; but for- tunately they are rare. The situation of the pudic artery upon the exterior of the pelvis admits the possibility of tying the vessel in the living subject; the plan of operation necessary for the purpose is similar to that to be adopted with the gluteal artery, only it must be performed lower down ; it is the same with that for the ischiatic artery; for determining the situation of which or the pudic the following directions are given by Harrison :*— " Place the individual on his face with the lower extremity extended and tire toes turned inwards: feel for the summit of the great trochanter, and for the base or articulated end of the coccyx ; these two points are on a level ; then draw a line from one to the other, and we may be certain that the pudic artery and the spine of the ischium are opposite the junction of the middle and internal thirds of this line." The ischiatic artery may be reached as easily, or even more so, than the * Vol. ii. p. 103. 837 gluteal ; but the difficulty which must attend the seeking for the pudic must be extreme. The external iliac artery, (arteria iliaca externa, Lat. ; arttrc iliaque externe, Fr. ; portion iliaque dc la erurale, Chauss. ; Aussere Iiuft-puhader, Ger.) is the vessel destined for the supply of the lower extremity, of which the portion contained within the abdomen, in the iliac region, is denominated the " external " iliac, in contradistinction to the artery of the pelvis, the " internal." It commences at the division of the primi- tive iliac artery, at a point intermediate to the body of the last lumbar vertebra, or the sacro- vertebral prominence, and the sacro-iliac articu- lation, and it terminates at the crural arch, at a point midway between the superior anterior spinous process of the ilium and the spinous process of the pubis,* or at the outer side of the ilio-pectineal eminence of the os innomina- tum. The point at which the vessel com- mences is not uniform either in all subjects or on the two sides of the same; depending upon the point at which the primitive iliac divides, which is variable, it will be higher or lower, nearer to the vertebra or to the articulation, according to the situation of the bifurcation of that vessel : on the right side of the body the artery commences for the most part nearer to the body of the vertebra than on the left, on which it is of course nearer to the articulation ; hence the artery arising higher upon the former is longer upon that side than upon the latter, the difference in length varying from a quarter to half an inch. The external iliac terminates in the femoral or crural artery, strictly so called ; but the distinction between the two is one only of convenience, inasmuch as they are but different stages of the same vessel ; there appears therefore much propriety in the * The situation of the artery at its termination is differently stated by different writers ; Boyer states it to be midway between the spinous proeess of the ilium and the symphysis pubis; Cloquet, midway between t lie spine of the ilium and the spinous pro- cess of the pubis ; Harrison, about half an inch to the pubic side of the centre of the crural arch. The relation of the vessel to the points between which it is placed, is probably not the same in all cases; but that assigned to it by Cloquet seems most generally applicable. According to Cooper, with whom Cloquet concurs, there are, in the male, 3^ inches from the symphysis pubis to the middle of the artery, and in the female 3|, while the distance to the superior anterior spinous process of the ilium is in the former 53., and in the latter six inches ; the artery must therefore ba external to the mid-point, being for the most part concave forward and inward above, and convex forward below ; but in this particular it is not uni- form, being sometimes nearly straight ; the degreo of its tortuosity also appears to depend upon the age of the subject and the plenitude of the vessel. The direction of the artery is oblique, and as the primitive iliac and it are continuous in the adult, the course of both the vessels maybe defined, during life, by a line extending from the umbilicus, or from half an inch below it, at its left side, to a point midway between the superior anterior spinous pro- cess of the ilium and the spinous process of the pubis, the upper extremity of the line varying according to the situation at which the aorta divides. 833 ILIAC ARTERIES. designation adopted by Chaussier, which, while it recognises the identity of the vessel throughout its course, sufficiently marks the grounds of distinction between its two portions. The external is somewhat smaller than the primitive iliac, but in the adult considerably larger than the internal ; its direction is down- ward, outward, and forward, and hence it forms with the primitive iliac a curve convex backward, and seems the continuation of that vessel ; its length is from three to four inches, and during its course it forms one or more Curvatures. Such is the disposition of the vessel in the adult; but in the younger subject it is different in some respects; in the foetus the external iliac is considerably smaller than the internal, and does not seem the continuation of the primitive iliac, which at that epoch is continued into the internal ; the external appearing rather as a branch or a smaller division from a trunk common to the other two ; after birth the relative disposition of the iliacs gradually changes, until they acquire that of the adult. The relations of the external iliac artery are as follows ; posteriorly, it corresponds through the upper half of its course to the lateral part of the superior aperture of the pelvis; inclining outwards as it descends, it corresponds in its lower half to the os innominatum, and the more perfectly, the nearer it approaches the crural arch, at which part it is placed in front of the bone, crossing it nearly at right angles, and separated from it by an interval occupied by the psoo-iliac aponeurosis and the psoas muscle. At its outset the external iliac vein is directly behind the artery, and on its right side, also the commencement of the primitive iliac vein, the artery crossing the junction of the two vessels, on that side, obliquely in its descent; during- the remainder of its course, the vein, though posterior to it, is also internal ; through- out the lower half of its course it lies upon the psoo-iliac aponeurosis, supported by the os innominatum, and at first separated from the bone only by the aponeurosis ; but as it pro- ceeds separated from it also by the tendon of the psoas parvus when present, and by the inner mar- gin of the psoas magnus, it is very near to the os innominatum, external to the ilio-pectineal emi- nence, and being here supported by bone, and made steady by its connections it may with certainty be compressed and its circulation perfectly commanded. Internally, the artery corresponds above to the aperture of the pelvis, to its viscera more or less intimately, according to their state of distension or contraction, and also to the small intestines which descend into it ; in the lower half of its course, the external iliac vein, which at its outset is behind or beneath the artery, is internal, though still some- what posterior to it ;at the crural arch the artery and vein are nearly upon the same level, being supported by the os innominatum ; the artery however somewhat anterior to the vein, but as the vein recedes from the arch it inclines less inward than the artery, and at the same time retreats more from the surface; and hence it gradually gets more completely behind the artery until at its junction with the primitive vein it is concealed by it anteriorly. The artery is covered by peritoneum, upon its inner side through a considerable part of its course ; above the membrane covers it com- pletely ; but as it descends the extent becomes less in consequence of the ascent of the vein ; which thus gradually intervenes between the artery and the membrane, and removes the latter from it altogether in the lower part of its course. When the primitive iliac divides at a high point, the ureter descends into the pelvis internal to the external iliac immediately after its origin ; this occurs more frequently upon the right side than the left. Beneath the perito- neum the artery is covered by an investment, of which presently again, attaching it superiorly to the peritoneum and inferiorly to the vein. Externally the artery corresponds through its entire course to the psoas magnus muscle, but it is separated from it by the psoo-iliac fascia, to which it is connected by its immediate invest- ment ; the relation of the artery and the muscle are, however, somewhat different at the upper and lower parts of the vessel's course; above, the artery does not lie upon the muscle, but rests against its inner side along its anterior part, while inferiorly it lies upon the inner margin of the muscle at the same time that it rests against it externally. The genito-crural nerve is situate along the outer side of the artery; this nerve, long and slender,a branch of the lumbar plexus, descends upon the psoas, extenal to the artery, and at first at a little distance from it ; as it proceeds, it approaches thevessel,andliesclosetoitenveloped in the fascia propria; at the lower part of its course its genital branch frequently passes in front of the artery. The anterior crural vein is also external to the artery ; but it is considerably posterior to it, separated from it by the outer margin of the psoas, between which and the iliacus it lies, and also by the fascia iliaca, which covers it ; the nerve is about half an inch from the artery at the crural arch ; as it recedes from the arch the distance increases. In front, the artery is covered immediately by a cellular investment, formed by the sub- peritoneal cellular structure — -the fascia propria — upon the posterior wall of the iliac fossa; this encloses both the artery and the vein and at the same time connects them ; it varies in its condition according to the subject, in some it appears a dense, but still cellular expansion, in others from the deposition of fat it forms an adipose stratum, which however still presents a more condensed character in immediate con- tact with the vessels ; it adheres closely to the surface of the fascia iliaca upon either side of the vessels and thus attaches them to it; it is prolonged upward upon the primitive iliac vessels, and below, it ascends between the peritoneum and the fascia transversalis upon the anterior abdominal wall ; upon the primi- tive iliac it is very thin and proportionally weak ; but as it descends it increases in thick- ness and strength until at the lower part of the ILIAC ARTERIES. 839 external iliac. It forms a stratum of some thickness and considerable resistance, deserving of much attention in a practical point of view; there are imbedded in it immediately above the crural arch, and superficial to the artery, one or more lymphatic glands; the genito-erural nerve also descends enclosed in this structure, at the outside of the artery. Beneath the investment, and immediately above the crural arch, an ex- pansion of limited extent, presenting frequently a true fibrous or aponeurotic character, arises from the front of the vessels, and passing forward becomes identified with the fascia transversalis upon its internal surface; thus connecting the vessels to the anterior part of the superior aperture of the femoral sheath, and closing the interval between these parts, which otherwise would be unguarded. In the second place the artery is covered anteriorly through about four-fifths of its course by the peritoneum of the iliac fossa ; in the inferior fifth, i.e., for from half to three-fourths of an inch immediately above the crural arch, the membrane passing from the front of the artery to the anterior wall of the abdomen leaves the iliac artery uncovered; and hence the practical inference that the external iliac artery may be tied without disturbing the peritoneum. Beneath the peritoneum the artery is crossed at the inferior part of its course by the sper- matic vessels, and at the superior, upon the right side very frequently by the ureter. Thirdly, the viscera of the iliac fossa on the one hand, or of the pelvis on the other, ac- cording to circumstances, cross or overlap it ; on the right, the ccecum and the termination of the ileum ; on the left, the sigmoid flexure and the commencement of the rectum, and on both sides the small intestines are placed in front of it. And when the viscera of the pelvis become distended and rise from the cavity they overlap it from that side. The third relation of the artery in front is the anterior wall of the iliac region ; the details of this it is not proposed to examine at length, but only so far as they may be concerned in the relations of the artery ; the structures com- posing the wall being numerous, they may be conveniently arranged into three sets, viz., the superficial, the intermediate, and the deep or lining structures. The superficial structures are three, the skin, the subcutaneous cellular tissue, and the fascia. Of these the first does not require to be dwelt upon ; the second is subject to much variety in its condition ; it forms a stratum of considerable thickness in every case ; when, however, the superficial cellular structure of the body is charged with much adeps, it then forms an uniform and thick stratum of fat without any distinction into lamina;; this is best exemplified at the early periods of life, particularly in children cut off by an acute disease; when, on the contrary, the body is emaciated, it forms a condensed cellular ex- pansion much thinner than in the former case, and divisible frequently into laminoe. This structure is continued from the iliac over the other regions of the abdomen, downward upon the thigh, and in the middle line upon the spermatic process of the male and the organs of generation. Numerous superficial vessels are contained in and ramify through it; these are derived from several sources, but that which is proper to the iliac region is the superficial epigastric artery which ascends from the femoral superficial to the aponeurosis of the external oblique muscle and intermediate to the inguinal rings. Beneath the subcutaneous stratum is the third superficial structure, the fascia ; this is a thin dense expansion by which the external oblique muscle and its aponeurosis are covered ; it is not confined to the abdomen, but is con- tinued into a similar expansion upon the ad- joining regions whether upward or downward ; it adheres closely to the muscular portion of the oblique, particularly at the junction of the muscular fibres with the aponeurosis along the linea semilunaris, but its connection to the aponeurosis itself is more free, an extensible and delicate cellular tissue being interposed. Hence it is easily detached from the latter; it is most dense, fibrous, and strong upon the iliac region ; as it ascends thence it becomes less dense and fibrous, and assumes more of a simply condensed cellular character; it is not equally distinct in every subject, in all it can be recognized at the crural arch, and for some distance above it, but as it recedes from the arch it frequently seems to be gradually re- solved and to cease. Below, it is attached posteriorly to the outer edge of the crest of the ilium, and along this line it meets the insertion of the fascia lata of the bock of the thigh ; in front between the superior anterior spinous process of the ilium and the spinous process of the pubis it descends over the crural arch, having only a cellular connection to it, and being separable with ease from it, as well as from the aponeurosis of the oblique ; immediately below the arch it is united to the superficial surface of the fascia of the thigh, both externally and internally, on the latter side passing back to the pectineal line of the pubis, into which it is inserted along with the pubic portion of the fascia lata; in the interval between the spinous processes of the pubis it is prolonged down- ward upon the spermatic processes, and is continued upon them in the form of a sheath into the scrotum, where it invests the testicle ; it is very thin and transparent upon the spermatic process. The existence of this structure, to which attention appears to have been first directed by Camper, can always be demon- strated however fat or young the subject may be, though, as has been stated, it is not always equally manifest ; it seems distinct from the subcutaneous cellular structure, which frequently forms a uniform and thick stratum of fat be- tween it and the skin. Different views have been taken of its nature ; by Scarpa it is re- garded as a prolongation of the fascia lata of the thigh, while others and the majority consider it as a continuation of the superficial fascia, so called, of the same part, and formed by the deep stratum of the abdominal subcutaneous cellular 310 ILIAC ARTERIES. structure converted by condensation or removal of its adeps into an expansion ; to me it appears that the view taken of its nature by Scarpa is cor- rect, not in the sense that it is a prolongation of the fascia lata, but that it is of the same nature, and that it is to the abdomen the same structure which the fascia lata is to the thigh ; it is a question entitled to consideration only for ac- curacy's sake, but I have frequently verified the inferior connections of this expansion such as they have been detailed, and further it appears to me that it is not properly continuous with the superficial fascia of the thigh, for if it be detached from the aponeurosis of the oblique muscle and the crural arch without injury to its connection with the fascia lata, and be then held perpendicular to the latter, the superficial fascia of the thigh may be removed from the angle which it will thus form with the fascia lata, and its connection still remain perfect : a favourable subject and a careful dissection will certainly be required for the purpose, but this circumstance will not invalidate the con- clusion ; it is also to be recollected in making the dissection, that the fascia detaches processes over the inguinal lymphatic glands. The structures of the second order of parts concerned with our subject, are the aponeurosis of the external oblique muscle, the internal oblique and the transversalis muscles; of these the first, which is immediately beneath the fascia, extends over the entire anterior wall of the fossa reaching from the linea semilunaris above to the crural arch below ; internally it is united with that of the other side in the linea alba, and inferiority it forms the crural arch by its border, which is attached externally to the superior anterior spinous process of the ilium, internally to the spinous process of the pubis, and in the interior to the iliac fascia and the fascia lata. The direction of this band is to be borne in mind, for it does not run directly from one of these points of bone to the other ; but it descends toward the thigh, and recedes from the surface at the same time that it passes in» ward, hence it is concave both forward toward the surface and upward toward the abdomen ; the cause of this direction is its connection inferiorly and posteriorly with the fascia lata and the fascia iliaca. The aponeurosis consists primarily of tendinous fibres which run in the same direction as the fibres of the muscle, i. e., downward and inward, parallel to each other, and also to the crural arch, though rather con- verging toward it internally, and thereby form a tendinous expansion ; the longitudinal fibres of the aponeurosis are crossed by others which run downward and outward ; these are very irregular in number and do not interlace with the former, to which they are superficial ; hence the aponeurosis does not possess great strength in the transverse direction, and its longitudinal fibres are liable to be separated, and deficien- cies to be thereby formed in the aponeurosis, which are not ^infrequently to be observed. The superficial inguinal ring is seated in the aponeurosis ; this aperture, for the particulars of which see the articles Abdomen and Herma, is of variable form and size ; in some cases it is elliptical, in others triangular ; in the male it is larger than in the female ; its position is oblique, the longer diameter inclining from the pubis upward and outward toward the superior anterior spinous process of the ilium ; its actual length is extremely variable, in some instances not amounting to half an inch, in others exceeding an inch. . The inferior part of the internal oblique and of the transversalis muscles, which alone is concerned in the anatomy of this part of the abdominal wall, may be distinguished into two parts, viz,, their muscular portion and their aponeurosis. The muscles are both, but more particularly the latter, very thin, though of great width ; they are placed the one within the other, and the internal oblique, which is super- ficial to the transversalis, also descends a good deal lower, so that its inferior margin approaches very close to the crural arch, leaving only suf- ficient space between them for the escape of the spermatic process, which it covers beneath the aponeurosis of the external oblique, and which in some instances passes between its fibres,* while the margin of the transversalis is at some distance from the arch, and rarely covers the process, at least to any extent, the process escaping from the deep ring, for the most part below the margin of the muscle ; Cloquet has even seen the margin of the muscle so far as two fingers' breadth above the point of escape of the cord, and its fibres are usually pale, fine, and scattered. The muscular fibres of the lower part of the two muscles are at- tached to the anterior extremity of the crest of the ilium and to its spinous process, also to the superior aspect of the outer part of the crural arch, the oblique to nearly the outer half of the arch, the transverse to the outer third or fourth, but the ultimate attachment of the latter is to the surface of the fascia iliaca above the arch, to which they adhere very intimately as they pass forward from the fascia ; they run inward nearly transversely, but convex forward in proportion to the prominence of the abdo- men, those of the oblique over the deep ring, and the spermatic process within the inguinal canal, those of the transverse above the ring, until they have both passed that point ; they then descend along the inside of the process, and at the same time recede from the surface so that they become posterior to it, and terminate as they descend in a thin irregular aponeurotic expansion common to the fibres of both mus- cles, and thence denominated " the conjoined tendon ;" though designated by an especial name, this is in reality only the inferior part of the general conjoined tendon of the two mus- cles which terminate between the umbilicus and the pubis in a common expansion ; this is placed superficial to the rectus muscle, and is inserted into the linea alba, the anterior margin of the crest of the pubis as far as its spinous process, and thence outward into the pectineal line of the bone, there forming the " conjoined tendon" of the anatomy of hernia. This struc- ture is situate behind the spermatic process, * Cloquet. ILIAC ARTERIES. 841 between it and the fascia transversalis ; it ap- proaches very near to the inner margin of the deep ring, and at its insertion into the pectineal line it meets and is identified with Gimbernat's ligament; it is closely adherent to the surface of the fascia transversalis, and hence that fascia presents an appearance of thickness and strength upon the inside of the deep ring, which it does not really possess. From the inferior margin of the internal oblique and from the superior side of the crural arch the cremaster muscle descends upon the anterior and external part of the spermatic process, forming one of the coverings of the process within the inguinal canal, of course concealing it after the division of the aponeurosis of the external oblique, and requiring to be detached from the arch along with the lower fibres of the internal oblique in order that the process may be fairly exposed. The deep structures of the anterior wall of the iliac fossa are also three, viz., the fascia transversalis, the fascia propria, and the peri- toneum. 1. The fascia transversalis is most remark- able in the iliac region, but it is not con- fined to it, being to be traced upward to the surface of the diaphragm, and backward round the interior of the lateral walls of the abdo- men. In the iliac region this fascia is interiorly first identified with the fascia iliaca from a short distance behind the anterior superior spinous process of the ilium to the outer side of the external iliac artery, or about the middle of the crural arch ; the line of its connection with the fascia iliaca runs downward, forward, and in- ward, at a short distance within the crest of the ilium and the crural arch, approaching the latter, however, as it descends, until at the outside of the artery it touches it; it is sepa- rated along this line into two lamina? which enclose the circumflex iliac artery between them ; there is, therefore, an interval between the arch and the line of connection of the two fascia? in which the fascia iliaca intervenes, and to the surface of this part of the fascia it is that the internal oblique and transverse muscles are attached. In the second place the fascia transversalis descends into the thigh beneath the crural arch, between it and the iliac vessels, and forming the front of their sheath; and, thirdly, it is attached upon the inside of the vessels, along the pectineal line of the pubis posterior to the conjoined tendon of the internal oblique and transverse muscles, between it and the peritoneum, and separated by it from the spermatic process, which is m front of both. Internally the fascia transversalis is con- nected to the edge of the tendon of the rectus. Midway between the superior anterior spi- nous process of the ilium and the spinous pro- cess of the pubes, and at from half to three- fourths of an inch above the crural arch, the spermatic process escapes from the abdomen, descending within a cylindrical prolongation of the fascia by which the process is enclosed, and which thus forms a sheath for the process. By detaching this prolongation from the fascia around the process, a circular aperture is formed in the fascia, which is the deep in- guinal ring, the situation of which has been just defined. On the inside of this opening- are situate the epigastric vessels, the artery, and vein or veins, the artery in the former case being next the ring, in the latter at times the outer of the two veins. 2. The fascia propria is a cellular stratum in- terposed between the peritoneum and the struc- tures of the abdominal walls which it lines ; it varies in thickness and condition at different parts and in different subjects ; at times it con- tains adeps, at others it is purely cellular, or forms a condensed expansion ; in the iliac region it is thicker upon its posterior than its anterior wall ; on the latter it increases in thickness as it descends towards the crural arch, being so thin towards the umbilicus that the peritoneum adheres very closely to the ten- dinous expansion of the muscles; at the deep inguinal ring it is more dense, and the perito- neum, the fascia transversalis, and it, are more intimately connected than at either side ; ex- ternal to the ring, between it and the spinous process of the ilium, it is so free that the pe- ritoneum may be separated without difficulty from the interior of the fascia transversalis, and along the crural arch it forms, from the external iliac artery outward, a soft mass, sometimes thick, occupying the interval left between the peritoneum and the fascia trans- versalis, at the reflection of the former from the iliac fossa to the anterior wall : upon this wall it encloses the epigastric vessels, the um- bilical ligament, and the spermatic vessels, and not only does it extend universally over the in- terior of the abdominal walls but it is prolonged through their several apertures upon the parts which pass through them, as in the case of the spermatic vessels. From the anterior wall of this region it passes to the posterior, where it lines the iliac fossa, and connects the peritoneum or the viscera to the iliac fascia ; at the outer part of the fossa it is remarkably free, soft, and easily lacerated, so that the peritoneum can be detached, pro- bably with greater facility at this than at any other situation; at its inner part it is even more abundant, thicker the nearer to the crural arch, forming the investment by which the iliac ves- sels are inclosed, and descending thence into the pelvis. Lastly, the peritoneum of the anterior wall is continuous inferiorly with that of the iliac fossa, being reflected from the one to the other at the distance of five or six lines above the crural arch — a fact deserving of much attention, since it permits the external iliac artery to be secured without disturbing the membrane. In its reflection from one wall of the region to the other it leaves immediately above the crural arch, between itself, the fascia transversalis, and the fascia iliaca, a triangular interval of some lines, occupied by the fascia propria, and at times at least by one or more lymphatic glands; this space is widest at the iliac artery and diminishes as it extends outward; this fact also deserves attention, inasmuch as it points out where the fascia transversalis may be di- vided, if necessary, in the operation of expo- 842 ILIAC ARTERIES. sing the external iliac with least clanger to the peritoneum, viz. on the outside of the deep inguinal ring and close as possible to the crural arch. The peritoneum of the anterior wall of the fossa is weaker toward the middle line than externally; it presents toward the abdo- men two depressions or recesses denominated by Velpeau " fossettes inguinales," internal and external; these depressions vary very much in their depth, sometimes hardly perceptible, at others of considerable depth and capacity, more especially the external, which is much the larger; they are produced by the projection of the umbilical ligament from the interior of the abdominal wall, and the reflection of the peritoneum round the ligament, by means of which a triangular fold, wide in proportion to the degree to which the ligament projects, is formed, the base of which is below, the apex above toward the umbilicus, and in the free edge of which the ligament is contained ; this fold separates the depressions, one being external to it, the other internal, between it and the urachus ; the external one, the bottom of which tends forward and inward, corresponds to some point of the posterior wall of the in- guinal canal, but its precise relation to it is uncertain, because of the irregularity of the position of the umbilical ligament ; at times it is identical with another slight depression situate on the outside of the epigastric vessels, which marks the situation of the deep inguinal ring, the ligament in such case being behind these vessels ; at others it corresponds to the wall of the canal, to the superficial inguinal or the deep femoral rings, the ligament being in these latter cases internal to the epigastric vessels. The branches of the external iliac artery de- serving of particular attention are usually two, the anterior or circumflex iliac and the epigas- tric arteries; throughout the superior part of its course the artery gives only minute branches to the peritoneum, the cellular tissue, the psoas muscles, and the lymphatics ; the other two, which have been mentioned, are given off im- mediately before the artery escapes from the abdomen. They arise at a very short distance above the crural arch, sometimes so high as three-fourths of an inch from it, at others at it, and sometimes again below the arch from the femoral ; they proceed one from the outer and the other from the inner side of the vessel^ sometimes opposite to each other, at others in- differently one above the other : occasionally they are given off from a trunk common to both; they are nearly of equal size, but for the most part the epigastric is larger than the cir- cumflex. 1. The anterior or circumflex iliac artery, ( arteria circumflexa iliaca or ilii ; Fr. artere circorijiexe iliaque., ou iliaqvc ou anterieure,) arises from the outer side of the external iliac on a level with or somewhat lower than the epigastric; it runs outward and upward above and paiallel to the crural arch as far as the superior anterior spinous process of the ilium; during this course it lies upon the fascia iliaca superficial to the psoas and iliacus mus- cles and the anterior crural nerve, and it is inclosed in a triangular canal, formed behind by the fascia iliaca, below and above by la- minae of the fascia transversalis, which divides at its union with the former, in order to inclose the artery. When the anterior abdominal wall has been thrown down, and the peritoneum with the fascia propria removed from the iliac fossa, the course of the vessel may be traced by a white line, which marks the union of the two fasciae, extending from the middle of the crural arch upward and outward within about three- fourths of an inch of the spinous process of the ilium; by the division of the fascia trans- versalis along this line the artery will be ex- posed. During its course toward the spinous process the artery gives branches to the psoas and iliacus, the transversalis and oblique muscles, and to the inguinal glands ; near the process it gives upward a considerable branch, which ascends in the anterior wall of the abdomen between the internal oblique and transversalis muscles, in front of the spinous process, serving with its accompanying veins as a guide in dis- section by which to distinguish between the two muscles; it divides into branches, which are distributed to the muscles, as also to the structures, which cover and line them, and communicate with branches of the epigastric, lumbar, and intercostal arteries. The circumflex artery pursues its course and runs backward around and within the crest of the ilium, internal to the transversalis muscle ; during its course it gives branches inward to the iliacus muscle which anastomose with si- milar branches from the iliolumbar, and up- ward to the lateral abdominal muscles, which are partly distributed to them, partly turn over the crest of the ilium and communicate with the gluteal artery, and in part communicate with the lumbar or intercostal arteries. Finally, the artery, very much reduced in size, anasto- moses freely with the termination of the ilio- lumbar, which pursues a similar course in a contrary direction around the interior of the crest of the ilium. The circumflex artery has been found by Monro to present an irregularity deserving of notice ; he has seen a branch from it, nearly as large as the epigastric, pass under the crural arch, about two inches from the symphysis pubis, and there divide into branches, which were distributed upon the symphysis and the fat and skin over the arch. 2. The epigastric artery, (Fr. artere epigiis- trique, A. sus-pubienne ) arises from the in- ternal and rather anterior part of the iliac artery, near to the crural arch ; the distance of its origin from the arch, however, is liable to variety ; for the most part it occurs about half an inch above it, but it is frequently nearer to it, or even at it, and occasionally it is below it, arising from the femoral artery ; it is given off, as has been stated, from that part of the iliac, which is left uncovered by peri- toneum, and its point of origin is posterior to, sometimes above, sometimes on a level with, and at others below the reflection of the mem- ILIAC ARTERIES. 843 brane from the posterior to the anterior wall of the abdomen. Its course is tortuous ; it passes forward and inward ; when its origin is low, or very near to the arch, at once upward; but when its origin is high, at first downward in front of the external iliac vein, and then changing its direction, when it has reached the reflection of the peritoneum, it ascends inward toward the outer margin of the rectus muscle, in front of the membrane, between it and the iascia transversalis ; it reaches the margin of the muscle from one and a half to two inches above the pubis, and then passing behind it enters its sheath, and continues its course upon the posterior surface of the muscle toward the umbilicus, and terminates by dividing into branches, which anastomose freely with de- scending branches of the internal mammary artery ; the main course of the vessel is there- fore oblique upward and inward ; and it may be defined by a line drawn from the junction of the middle and inner third of the crural arch to within half an inch upon either side of the umbilicus. The artery, when its origin is high, is situate, at its outset, behind the peritoneum, posterior to the deep inguinal ring ; in the rest of its course it is at first beneath and then before it, in immediate contact with it from the crural arch to the edge of the rectus, and enclosed in the fascia propria, but in the remainder sepa- rated from it by the back of the sheath of the muscle ; it therefore forms in this case a curve in which the reflection of the peritoneum is contained, and through which the vas deferens forms a similar curve, — the aspect of the curves being however different, the convexity in the former directed downward, and in the latter outward and somewhat upward — the two cords hooking round each other; in its ascent from the crural arch it is contained in the posterior wall of the inguinal canal, between the fascia transversalis and the peritoneum, crossing the canal nearly at right angles, and intermediate to the two rings, being distant from the outer part of the superficial one, according to the size of the aperture, from half an inch to an inch and a half, and in its relation to the deep ring varying from the margin of the aperture itself to four or five lines distance from it. It is accompanied sometimes by one, at others by two veins ; in the former case the artery is always external and next to the margin of the ring; in the latter, one of the veins is at times between it and the aperture. The relation of the artery to the inguinal rings indicates at once that which it must hold to the neck of the sac in the two original forms of inguinal hernia ; in the oblique or external inguinal hernia it is, as a matter of course, placed beneath and on the inside; and in the direct or internal inguinal, upon the outside of the neck ; but in the former it must, in consequence of its natural vicinity to the ring, and the dila- tation of the latter, be close to and surround the neck upon the two sides mentioned, while in the second, unless the aperture be much enlarged, it will be at a greater or less distance from it; the risk of danger to the vessel from cutting to the side, at which it lies, in a stran- gulation at the neck of the sac, must therefore be much greater in the former than in the latter. In the case of a hernia originally ob- lique and become direct by long continuance, the artery carried inward along with the deep ring, from the displacement of which the hernia assumes the character of the direct form, the artery is of course situate still upon the inside of the neck, which at the same time it surrounds to a greater extent than in the former instances ; this third, though secondary, form of inguinal hernia presents another case, in which the relation of the vessel to the neck of the sac demands attention the more that the true nature of the case being obscure and the hernia originally and secondarily direct, being thence liable to be confounded, it is most im- portant that it should be borne in mind that the artery may be to the one side or the other, according as the hernia has been originally or secondarily direct. The epigastric artery is also situate, in its ascent, external to the deep femoral ring ; its distance from it, in the natural state, is about half an inch ; but when hernia is present, and the neck at all large, the epi- gastric vessels are close to its outer and anterior side, the vein, however, being between the artery and the ring; when the obturator artery arises from the epigastric, the propinquity of the latter to the ring is increased. The branches of the epigastric artery are numerous, and some of them important. Its first branches are two given off between its origin, and the deep inguinal ring, higher or lower, according to the situation of the origin of the epigastric itself ; they arise, in some in- stances separately, in others by a single origin, and they run over to the posterior surface of the pubis, the other to anastomose with the obturator artery ; the former, the pubic branch, runs inward above Gimbernat's ligament, sometimes along its anterior, sometimes along its posterior margin, to the back of the pubis, and according to its course is liable to be situate before or behind the neck of a femoral hernia. The second, the obtu- rator branch, runs backward, downward and inward toward the superior aperture of the pelvis, i.e. in the direction, which the obturator artery when arising from the epigastric takes; having descended into the pelvis it joins the obturator at a variable distance between the origin of that vessel from the internal iliac and the sub- pubic foramen; frequently it divides at the brim of the pelvis into two, of which one joins the obturator and the other runs backward along the brim and anastomoses with the ilio- lumbar artery. This branch holds precisely the same relation to femoral hernia which the obturator when arising from the epigastric does; it is very variable in size, and it is upon its de- velopment as compared with that of the origin of the obturator from the internal iliac that depends, whether the former shall seem a branch of the latter, or of the epigastric ; when the origin of the obturator from the iliac has become wanting, this branch takes its place and becomes the obturator. 344 ILIAC ARTERIES. 2. The epigastric artery in passing the deep inguinal ring gives a branch, which goes out through the ring in company with the spermatic process, descends to the scrotum and is distri- buted to the structures of the cord, to the tunica vaginalis, and to the cremaster, and anas- tomoses with branches of the spermatic artery ; it is denominated by some the inferior sper- matic artery. 3. As the artery ascends in the abdominal vvall it gives to either side numerous branches, which are distributed among the structures of the wall, anastomosing externally with branches of the circumflex iliac, of the lumbar and the inferior intercostal arteries, and internally with those of the artery of the other side ; many of these branches ultimately become superficial, passing through the muscles, and through aper- tures in the aponeurosis of the external oblique ; they terminate in the superficial structures, anastomosing with the other superficial vessels. 4. Finally, the epigastric artery terminates by two or more long ascending branches, which meet and anastomose with branches from the internal mammary artery. Methods of operation for the ligature of the iliac arteries. — The methods of operation for the internal and primitive lliacs being but mo- difications of those adopted for the external, I propose to detail the latter first. The operation in each case may be resolved into three stages, viz. 1, the division of the structures of the abdominal wall ; 2, the dis- placement of the peritoneum with the inter- vening viscera; 3, the management of the artery and the parts immediately related to it. Several plans have been proposed for exposing the external iliac artery ; these may be regarded as, all, modifications of the same ; yet their number, the existence of points of difference leddmg to results of some importance, and the advantage to be derived from a clear appre- hension of them, render it desirable to distin- guish them so far as they present distinctive characters deserving notice. I propose, there- fore, to particularize five methods, between which operators may have occasion to select. In the first the line of incision is straight, and corresponds to the course of the artery. In the second the line of incision is also straight, and inclines away from the course of the artery toward the superior anterior spinous process of the ilium. In the third the line of incision is curved, convex downward toward the thigh, and crosses the course of the vessel. In the fourth the line of incision is straight, and transverse to the artery's course. The fifth, which I would specify, is a modification of the third, by which that plan may be rendered more generally ap- plicable. The first is, that which was adopted by Abernethy, by whom the artery was first tied, A.D. 1796, and is now generally known as his method, of which the following is his own account : — " I first made an incision, about three inches in length, through the integuments of the abdomen, in the direction of the artery, and thus laid bare the aponeurosis of the ex- ternal oblique muscle, which I next divided from its connection with Poupart's ligament, in the direction of the external wound, for the extent of about two inches. The margins of the internal oblique and transversalis muscles being thus exposed, I introduced my linger beneath them for the protection of the peri- toneum, and then divided them. Next, with my hand I pushed the peritoneum and its con- tents upwards and inwards, and took hold of the artery."* The second method seems due to several, and first also to Abernethy. This may seem doubtful, from the account of his second ope- ration originally given by himself, in which he says merely that " an incision of three inches in length was made through the integuments of the abdomen beginning a little above Pou- part's ligament, and being continued upwards ; it has more than half an inch on the outside of the upper part of the abdominal ring, to avoid the epigastric artery."f But in his collected worksj of different dates it is expressly stated of this and his subsequent operations that the incision "began just above the middle of Poupart's ligament, and consequently external to the epigastric artery, and was continued upwards, but slightly inclined towards the ilium." The plan adopted by Frere differed not much from this. This method appears however more particularly attributable to lloux, who seems to have been the first to give specific instructions for it, recommending that the be- ginning of the incision should never be further than half an inch from and a very little higher than the anterior superior spine of the ilium, and that it should be carried very obliquely downwards to the middle of Poupart's liga- ment^ The third method is that of Sir A. Cooper, in which the incision is begun just above the abdominal ring, and is extended downward in a semilunar direction to the upper edge of Poupart's ligament, and again upwards to within an inch of the anterior superior spinous, process of the ilium. This incision exposes the tendon of the external oblique muscle : in the same direction the above tendon is to be cut through, and the lower edges of the in- ternal oblique and transversalis muscles ex- posed : the centre of these muscles is then to be separated from Poupart's ligament : the opening by which the spermatic cord quits the abdomen is thus exposed, and the finger passed through it is directly applied upon the iliac artery above the origin of the epigastric and circumflex ilii arteries : the next step of the operation consists in gently separating the vein from the artery by the extremity of a director or the end of the finger ; the aneurismal needle is then passed under the artery. || The fourth is that of Bogros, in which the line of incision is, as I understand it, straight, from two to three inches long, immediately above the crural arch, and has its extremities * Surgical Works, 1830, v. 1, p. 292. t Surgical Observations, 1804, p. 214. t Surgical Works, 1830, p. 396. § Cooper's Dictionary, and Nouveaux Elemens do. Med. Op. || Cooper's Lectures by Tyrrell, v. 11. ILIAC ARTERIES. 845 equidistant, the external from the spine of the ilium, and the internal from the symphysis of the pubis. The aponeurosis of the external oblique muscle having been laid open in the direction of the crural arch upon a grooved director, the spermatic cord with the cremaster is to be drawn upward beneath the superior lip of the wound ; the deep ring dilated with the point of the finger ; the epigastric vessels, if a guide be necessary, followed toward their origin ; the cellular structure and lymphatic glands situate above the arch upon the artery separated ; and the vessel exposed and isolated.* In the fifth method, which is but a modi- fication of Cooper's, the outer extremity of the incision as directed by him is prolonged to, or beyond the superior spinous process of the ilium in proportion to circumstances. Before these methods be contrasted with each other, a few additional remarks seem re- quired in reference to the operation however performed. 1. The posture of the patient should be such as will most relax the abdominal muscles in order to prevent as much as possible their pressure upon the viscera, and to allow the more easy separation of the edges of the wound. The shoulders should be raised and the legs bent upon the pelvis. 2. It seems desirable that unless the super- ficial wound be longer than has been stated, the division of the aponeurosis of the external oblique should be of equal extent. 3. The recommendation to divide that apo- neurosis upon a director appears judicious as a means both of facility and safety. 4. Where it can be used the finger seems a safer instrument with which to separate the internal oblique and transversalis muscles from the structures beneath, for it will be readily understood that the extremity of a director might be easily thrust through the peritoneum in the execution of this step. 5. It must be borne in mind that between the muscles and the artery there are to be ex- pected beside the peritoneum two other struc- tures : 1. the fascia transversalis; 2. the im- mediate investment of the vessels. The fascia transversalis may either be treated in the manner directed by Cooper, viz. by dilating the deep ring, or be lacerated with the nail, as recom- mended by Guthrie, but it is to be recollected that a prolongation of the fascia descends upon the spermatic cord, and that therefore there exists no opening, and that the fascia varies in strength, and may at times be found so strong as to require more force to lacerate it than it may be deemed proper to exert. In such case an opening may be made through it with the knife, and enlarged upon a director if necessary. This may be effected by either of two methods, viz. either by dividing the prolongation of the fascia, which descends upon the spermatic process, " having been first raised with a forceps, to a sufficient extent to admit the forefinger to pass upon the cord into * Archives GenOraks ck Med., t. iii. p. 408. the internal abdominal ring," — a proceeding adopted by Mott, and which offers a safe mode of opening that structure ; or by cutting the fascia upon the outside of the ring, in the di- rection toward the superior spine of the ilium, to such an extent as may allow the introduction of the director or the finger : the section can- not be attempted safely inward, because of the vicinity of the epigastric artery, which is so near to the inner side of the deep ring that it must in such case be exposed to imminent danger, situate as it is between the fascia and the peritoneum ; on the other hand the more close attachment of the fascia to the latter membrane in proportion as it recedes from the crural arch forbids the section of the fascia di- rectly upward ; while the existence of the tri- angular interval, which has been described, between the fascia and the peritoneum imme- diately above the arch renders the membrane safe from injury in a division outward near to the arch : it must however be recollected that in approaching the arch the circumflex ilii artery is also approached and endangered, so that the incision should not be brought too near to that part, but made in the direction mentioned, nor in any case be larger than will suffice for the introduction of the finger or the director. 6. The immediate investment of the vessels frequently opposes great resistance to the sepa-- ration of the artery and vein, and to the iso- lation of the former; this impediment is due not merely to the strength of the investment, but also to the absence of a resisting support behind the vessel as it recedes from the pubis, in consequence of which it yields to the pres- sure exerted to separate it. In such case the nail, the director, or the knife has been recom- mended for the division of the expansion ; Abernethy made a slight incision on either side of the artery. The nail does not seem the best instrument in this instance, because, by the use of it the vessel must be a good deal dis- turbed, a circumstance to be avoided when- ever it can be ; the knife again must be attended with risk unless used with great caution and in steady hands, and the risk is the greater when the incision is made at one side of the artery, since the vein is thereby endangered ; it would seem a safer proceeding and one less likely to disturb the artery unnecessarily, if, when it can be done, the investment were pinched up with a forceps over the middle of the artery and then divided to the extent to which it may have been raised, after which, with the director or the blunt aneurism- needle, the artery may be isolated with facility while the investment is drawn to either side with the forceps. 7. It is to be borne in mind that one or more lymphatic glands usually lie in front of the artery imbedded in the cellular structure which forms its investment, and that these may be to be displaced. 8. In operations upon the iliac arteries, more particularly when performed after the method of Abernethy, or upon the internal or primi- tive vessels, a protrusion or bearing down of 846 ILIAC ARTERIES. the abdominal viscera is to be expected which has been found a great obstruction to the operation : this will be most effectually pre- vented by the use of purgatives previous to the operation ; by posture, the abdominal muscles being thereby relaxed as much as possible ; and during the operation, if it occur, by the use of curved spatulas of considerable width and curve, as used by Mott, with which the viscera may be supported. 9. In the passage of the ligature it will always be necessary to be assured that the genito-crural nerve is not included ; but it may be avoided without difficulty, and can seldom require to be divided. lis situation should be borne in mind, viz. above external to the artery, below external or anterior. Lastly, it would seem the safer plan to pass the needle and ligature from within outward, inasmuch as the vein is internal to the artery. In Cooper's Lectures edited by Tyrrell, it is directed to pass the needle from without ; by so doing there is less risk that the genito-crural nerve shall be included, and in high operations, since the vein is situate so much beneath the artery at the superior part of their course, it will not be thereby much endangered, but at the lower part the vein must certainly be more exposed by that mode of passing the ligature than by the contrary one, while the nerve may be avoided without difficulty. We shall next consider the comparative merits of the several plans of operation. In the method of Abernethy the direction of the line of incision is attended with the following consequences. 1. It requires a more extensive division of the oblique and transversalis mus- cles, and hence is more likely to be followed by weakness of the abdominal wall. 2. Fal- ling, as first performed by him, nearly upon the course of the epigastric artery, it exposes that vessel to be divided, though in the me- thod adopted by him in his latter operations this risk must be very much diminished, if not removed. 3. The extent to which it is neces- sary to divide the internal oblique and trans- versalis muscles must expose the peritoneum lining the anterior wall of the abdomen to be lacerated or divided during their separation. 4. The parallelism of the vessel and the wound must render it necessary to expose a greater length of the former, in order to effect its separation from the contiguous parts and to pass a ligature round it. 5. It is therefore necessary to detach the peritoneum in all cases, and to a greater extent than may be necessary or required by a different method. 6. The peritoneum must be detached to an equal ex- tent from both walls of the abdomen — from the anterior as much as, or it may be more than, from the posterior. 7. The protrusion of the viscera must be more likely to occur. It is asserted by some* that the spermatic cord is more exposed to injury in this method ; but it appears to me that it cannot be more so than in others, and that it ought to be more safe. * Velpeau. The second method is free from many objec- tions to which others, and especially the first, are exposed. 1. It does not endanger any vessel but the superficial epigastric. 2. It does not endanger the spermatic cord. 3. Probably it does not tend to weaken the abdominal wall as much as the first method. 4. It renders necessary a much less extensive detachment of the peritoneum, since the line of incision falls so much nearer to the inferior reflection of the membrane. Add to these that by it the artery may be reached at as high a point as by the first, and no doubt can remain that it is to be preferred to it ; and in cases requiring a high ligature of the vessel there is none, save the modification of Cooper's method, which can be considered equally eligible. It is still, however, subject to the same conditions with the first, only in less degree. In the method of Cooper, on the contrary, the internal oblique and transversalis muscles are divided to but an inconsiderable extent, and the division of the aponeurosis of the external oblique approaches more to the course of its fibres. The direc- tion of the incision being transverse to that of the artery, the vessel may be exposed, and a ligature passed round it without stripping it to a great extent and with little disturbance of it. Again, for the same reason and because of the vicinity of the incision to the crural arch, the vessel may be exposed either without dis- placing the peritoneum at all, or displacing it but little ; and when it is necessary to displace the membrane, that may be effected with the least possible disturbance of it, inasmuch as, because of the propinquity of the line of in- cision to the reflection of the membrane, it is not necessary to detach the latter from the anterior wall of the abdomen. It must also be less exposed to the protrusion of the viscera, and when the vessel is tied below, the reflection of the peritoneum must be exempt from it. This method permits the artery to be reached at from an inch to an inch and a half above the crural arch. On the other hand this method endangers the epigastric artery and spermatic cord more than the others ; the former because the line of incision crosses the vessel's course, com- mencing internal to it, and the latter because the line of incision crosses and sweeps over the cord in describing its curve. Velpeau con- siders that there is greater danger to these parts in the method of Abernethy, but I cannot concur in this opinion, for the lower extremity of the incision alone can fall upon the situation of the cord, and in the mode adopted by him in the majority of his operations, the line of incision was external to that of the epigastric artery. Experience too proves that there is greater danger of dividing the epigastric artery in the method of Cooper, since the accident has occurred more than once in it, and in the most dexterous hands; thus Averill relates that the artery was wounded by Dupuytren, and Guthrie also states that he has seen the artery divided in the performance of this operation, while I am not aware of an instance in which the trunk of the artery has been divided in the ILIAC ARTERIES. 847 method of Abernethy. But these objections to the method of Cooper, however serious in themselves, seem of insufficient weight when contrasted with those to which the plan of Abernethy is subject, more especially since they only require caution to be effectually ob- viated, while the others are inseparable from the plan to which they apply. And hence the preference has been given to his method, by the greater number of those* who have had opportunities of experimentally testing the comparative claims of the two in all cases where it is applicable ; i.e. in those instances in which the aneurismal tumour has so little encroached upon the crural arch, or in which there is so much reason to consider the artery in a healthy condition immediately above the arch, that it may be with propriety tied near to that part. Sabatier is of opinion that the method of Abernethy should be preferred in every case ; but the number of authorities in favour of the other is so great, that we must consider its greater eligibility as a decided question. And the method of Cooper pos- sesses the additional and great recommendation that it may at any time be so modified by the prolongation of the upper extremity of the in- cision, as to be adapted to every case, so that in instances, in which it may be found neces- sary to tie the artery at a greater distance from the arch than the original plan will permit, this modification of it may be adopted even in the course of the operation : for the most part surgical writers recommend a preference of Abernethy 's first plan in such circumstances ; but to this all the same objections which have been already stated, apply, and forbid its adop- tion, while another less subject to them and not less efficacious presents for selection. Abernethy's plan certainly promises one ad- vantage, viz. that the line of incision being nearer to that of the artery the depth of it from the surface is likely to be less, unless where the abdomen is very prominent, than' in the latter, in which the obliquity of the direction must increase the depth of the wound, and for the same reason it may be more easy to obtain a view of the vessel, and to direct the opera- tion by the sight, which must be more difficult in the latter, and in proportion as the point at which the operator aims is higher ; yet, not- withstanding this circumstance in favour of the method of Abernethy, and the preference given by several to it in such cases, the method of Cooper, modified as has been explained, ap- pears to me still preferable, inasmuch as the greater disturbance of the peritoneum, the risk of injuring it in front, and the greater debility of the abdominal wall likely to be the con- sequence of Abernethy's method, seem to out- weigh its advantages ; there is beside another disadvantage attending the latter and a cor- responding advantage attending Cooper's plan, which must be experienced when an aneuris- mal tumour occupies the iliac fossa, viz. that, by the former the peritoneum must be detached from all the front of the tumour, while in the * Norman, Todd, Vclpcau. latter the lower and inner part of it may be left undisturbed, and this I consider a matter of some importance. The method of Bogros has been proposed as an improvement upon that of Cooper, under the impression that in the latter the incision, which makes nearly a right angle with the artery, corresponds to the vessel only by its internal ex- tremity, while in the one which Bogros proposes the middle of the incision corresponds directly to the artery ; by this plan he further maintains that greater facility in the operation is ob- tained, and the artery may be exposed nearly an inch above the crural arch without disturb- ing the peritoneum, while in Cooper's the membrane must be always displaced, and the ligature can be applied at only a very short distance from the arch. Bogros plainly under- stands Cooper's incision to commence at -the internal abdominal ring, and in such case his objections would be well founded. It is cer- tainly to be regretted that Cooper has used an ambiguous expression, which has led others beside Bogros to mistake his meaning; but if reference be made to his description of the anatomy of hernia it will be found that by the " abdominal" he intends the superficial in- guinal ring, and if so, that the sole difference between his and Bogros' plan is that in one the line of incision is straight while in the other it is curved, whence the comparative results must be the reverse of those inferred by Bogros, so far as the facility of securing the artery and of reaching it at a greater distance from the crural arch is concerned. If however it be desired to secure the artery immediately above the crural arch, between it and the reflection of the peri- toneum, as may occur in cases of femoral aneurism, the method of Bogros furnishes a plan fully adequate to the intention, free from the necessity of disturbing the peritoneum and easy of execution ; at the same time that it is subject to the objection, that, unless care be taken to prevent it by tracing the vessels to their origin, which must render the operation more complicated and delicate, the artery is more likely to be tied below the origin of the epigastric and circumflex arteries by this than by any other plan, and this upon two accounts had better be avoided, so that all things con- sidered this plan appears to me not so eligible as that of Cooper, in which it is altogether optional with the operator whether he shall disturb the peritoneum or not, or whether he shall tie the vessel immediately above the arch or farther from it, the one method being ap- plicable to all cases, and not requiring, perhaps during the operation, a transition to another, after that the first has been found insufficient. The modification of Cooper's plan, which has been enumerated as a fifth method, can be required only in those cases, in which it may- be necessary to reach a very high point of the external or the primitive iliac. In such it will be a question whether to adopt Abernethy's original method, the second method, or the one under consideration : for myself it appears to me that the first ought to be abandoned in operations upon the external or primitive iliacs, 848 ILIAC ARTERIES. unless there be something peculiar in the par- ticular case to justify its adoption. The ad- vantages of the second method have been partly stated ; to these is to be added that the line of incision will be made to correspond more to that of the artery than by the last method, and consequently the wound will be less oblique in depth, whence probably there will be less difficulty experienced in holding aside the parts which intervene between the surface and the vessel ; and certainly the operator, who may be apprehensive of injuring the epigastric and circumflex iliac arteries or the spermatic process, will do well to adopt it. Still for some reasons I feel disposed to prefer the last, for 1, it re- quires less disturbance of the peritoneum ; 2, it appears to me that the exposure of the vessel must be greatly facilitated by carrying the lower extremity of the incision across the course of the artery to its inner side, which is not accom- plished by the second method ; 3, a semilunar line of incision furnishes a wound of greater length, and capable of being more widely opened than a straight one, while caution will secure the spermatic process and the epigastric artery from injury ; and if a branch of the circumflex iliibe, as it is likely to be, divided, it may be tied with ease. This was the me- thod adopted by Mott in the operation, in which he tied the primitive iliac artery'; a case which sufficiently establishes the adequacy of this plan for the high ligature of the vessel, at the same time that it displays in a strong light the difficulties for which the operator must be prepared. In such cases the method of di- viding the internal oblique and transversalis used by Mott may be adopted with advantage, viz. after having opened the fascia transversalis to insinuate the finger between it and the peri- toneum, and guided by it to divide both mus- cles at once from within. It must not be forgotten that it is not uncommon to find the ureter crossing the internal iliac artery, upon the right side, near its origin. Operations for the ligature of the internal iliac artery. — The method adopted in this operation by Stevens, by whom the artery was first tied, and that recommended by the ma- jority of writers, is similar in principle to the first plan of Abernethy for the external iliac, and differs from it only m the length of the incision, which, according to Guthrie, should be five inches, beginning about half an inch above Poupart's ligament and about the same distance to the outside of the inner ring; it should be nearly parallel to the course of the epigastric artery, but a little more to the out- side, in order to avoid it and the spermatic cord, and have a gradual inclination inwards toward the 'external edge of the rectus muscle : according to Hodgson the centre of it should be nearly opposite the superior anterior spinous process of the ilium. The aponeurosis of the external oblique, and the internal oblique and tranversalis muscles having been divided with the same precautions to avoid the peritoneum, as in the other case, the fascia transversalis is to be torn through at the lower and outer part, so that the fingers may be passed outward towards the ilium, and the peritoneum detached from the iliac fossa, and turned with its contents inward by a gradual and sidelong movement of the fore and second finger inwards and upwards, until passing over the psoas muscle the ex- ternal iliac artery is discovered by its pulsation. This is then to be traced upward and inward toward the spine, where the origin of it and the internal iliac from the common iliac trunk will be felt. The artery is to be traced down- ward from its origin and separated with care from its connections, and more especially the vein. The sides of the wound should now be separated and kept apart with curved spatuku in order that the surgeon may, if possible, see the artery, and have sufficient space fin* passing the ligature. Great care must be taken to avoid every thing but the artery ; the peri- toneum which covers, and the ureter, which crosses it, must be particularly kept in mind ; the latter may be separated with ease, and usually accompanies the former as it is being detached from the artery. The situation of the external iliac artery and vein, which have been crossed to reach it, must be always recollected, and, if possible, they should be kept out of the way and guarded by the finger of an assistant.* This method has in this case a recommendation, which it does not possess for the other iliacs, viz. that, as it is necessary in tying the internal iliac to descend more or less into the pelvis, it is desirable that the external wound should be as near as possible to the aperture of the cavity, but the danger to the peritoneum must be even greater because of the greater extent to which it must be separated, and the closer attachment of it to the ten- dinous than the muscular structure of the abdominal wall. It, therefore, seems to me a question whether even in this case the line of incision here recommended should be adopted, and whether it would not be better to have recourse to that either of Roux or Cooper. Gf the two perhaps the former may be best adapted to the internal iliac for the reason just assigned ; though, if the inferior extremity of the incision be not carried beyond the middle of Poupart's ligament, difficulty must be ex- perienced in exposing the vessel and passing the ligature; therefore here again I am dis- posed to prefer the semilunar line of Cooper, only not brought so close to the crural arch as for the external iliac, and prolonged, as di- rected by Velpeau, two inches at its external extremity. It is recommended to pass the ligature from within outward because the internal iliac vein is posterior to the artery ; this appears to me, however, not the most judicious plan, by it the point of the needle must be first carried out- ward and then forward and inward in order to pass round the vessel : now the external iliac vein is immediately external to and crossed by the artery; the junction of the two iliac veins is also external to the artery, and the internal one, though posterior, is at the same time ra- ther external to it. In such a case the course * Guthrie on Diseases of Arteries, p. 371-2. ' ILIAC ARTERIES. 849 to be pursued must be very much influenced by the convenience of the moment; but it would seem the better plan, where a choice can be made, to pass the needle first backward between the artery and the external iliac vein, and then inward behind the artery toward the pelvis, by which plan the veins will be more surely avoided, and more space will be ob- tained for seizing the ligature. In this as well as every operation upon the iliac arteries, the spermatic vessels must be kept in mind, inasmuch as they require atten- tion as much as the ureter ; they are usually, however, like it, removed with the peritoneum. Velpeau suggests the possibility of rupturing the ilio-lumbar artery in isolating the internal iliac, and the risk ought not to be overlooked. Ligature of the primitive iliac artery. — Any of the methods recommended, whether for the internal iliac or the external at a high point, will answer for the ligature of the primitive iliac. Guthrie gives the preference to that upon Abernethy's first plan in this as in the case of the internal iliac ; but it appears to me that here, at all events, the method of Roux or the modification of Cooper's operation is to be preferred ; for, beside that there does not exist in this case the reason for approximating the line of incision to the aperture of the pelvis, which applies to the internal iliac artery, the situation of the aneurismal tumour in front must render the direct line of incision less convenient than a lateral one, and by the adoption of the for- mer there must be incurred a great exposure of the peritoneum without a commensurate advantage ; the necessity also of stripping the membrane from all or a great part of the front of the aneurism, incurred by this plan, must be very objectionable. The length of incision recommended by Guthrie is five inches at the least, and may be required of even greater extent; thus Mott was obliged to extend it in his case upward and backward, about half an inch within the ilium, to eight inches : he adopted the principle of Cooper, commencing his first incision " just above the external ab- dominal ring, and carrying it in a semicircular direction half an inch above Poupart's liga- ment until it terminated a little beyond the anterior superior spinous process of the ilium, making it in extent about five inches." It is likely that a longer incision may be necessary in this method when applied to the primitive iliac than in that recommended by Guthrie; the greater length of the external incision is doubtless an objection of secondary impor- tance; but it is probable that, when the pri- mitive artery is to be tied, little will be gained by commencing the incision so low as was done by Mott, and that it would be more ad- vantageous to carry it upward rather than downward ; such appears to have been the design of Crampton in the operation per- formed by him for the ligature of the primitive iliac, in which the line of incision was curved, concave toward the umbilicus, and extended from the anterior extremity of the last rib down- ward beyond the superior anterior spinous process of the ilium, and since unnecessary VOL. II. division of the abdominal parietes is of course to be avoided, and the leaving them entire at the lower part must be attended with two good results, viz. avoidance of the aneurism and less subsequent danger of pecuniary protrusion, I cannot but regard this plan as a desirable addition to the methods of proceeding when the primitive iliac is the vessel to be tied. In passing the ligature the difference of the relation between the vein and artery of the opposite sides is to be borne in mind, the former being external to the artery on the right and internal on the left, on both sides however being upon a posterior plane. The obstruction to the course of the opera- tion caused by the protrusion of the viscera is to be expected ; in that of Mott it is described as very great, while no mention is made of it in Crampton's. This difference was probably the consequence of the difference in the site of the wounds. The separation of the artery and vein is more easily effected than in the case of the external ihacs, because their investment is less thick and resisting. The diversity presented by the arteries of the opposite sides suggests a difference as to greater practicability and probability of success on one as compared with the other ; the artery of the right side being longer than the left presents greater room for the application of a ligature at a sufficient distance, whether from the seat of the disease or from the origin of the vessel, while that of the left being more per- pendicular in its course and nearer to the left side of the body ought to be more easily ex- posed ; but it is to be recollected that this dis- position is not uniformly present. Before undertaking an operation upon any of the iliac arteries it will be advantageous to determine, so far as possible, the relation of the vessel, which is to be the subject of.it, to the superficial points of the abdominal wall. This must be understood to be intended only as an approximation, but by attention to the follow- ing circumstances it will prove sufficiently close to serve the desired purpose. The mean point, at which the aorta divides and the pri- mitive iliac commences, is half an inch below the umbilicus at its left side, and thit at which the external iliac terminates is midway between the symphysis pubis and the superior anterior spinous process of the ilium : of course a line connecting these points will define the general course of the primitive and external iliac arte- ries. The length of the primitive iliac being from two to three inches, the extent of its course may be determined by the subdivision of this line. The point of demarcation be- tween the primitive and external iliacs, and which will serve to mark the orfgin of the in- ternal and external, as well as the termination of the primitive, may be further determined by a line extending from the crest of the ilium about one inch and a half behind its anterior superior spinous process to a similar point on the other side; such a line will traverse the sacro-vertebral articulation posterior to the di- vision of the primitive iliac, and by its decus- sation with that before mentioned will mark 3 K 850 ARTERIA INNOMINATA. more particularly the point of division of the vessel,* which will also correspond nearly to the centre of a line drawn from the anterior superior spinous process of the ilium to the umbilieus.f The practicability and success of these ope- rations have been so long established that they do not now require to be insisted upon. When the external iliac has been tied below the origin of the epigastric and circumflex ilii branches, the circulation of the limb is main- tained through the communications of the branches of the internal iliac with those of the femoral, of which the principal have been ascertained by Sir A. Cooper} to be the gluteal with the external circumflex, the obturator with the internal circumflex, and the ischiatic with the profunda, and through those of the circumflex iliac with the same. (See Femoral Artery.) When the ligature has been applied above the origin of these branches, the circulation is esta- blished also through their communications with the internal iliac, the internal mammary, the inferior intercostal and lumbar arteries. The ligature of the internal iliac artery can cause little interruption of the supply of blood to the parts to which it is distributed ; its com- munications are so numerous and free, exter- nally and inferiorly with the external iliac and femoral arteries ; inward with that of the other side, and upward with the aorta through the middle sacral and hemorrhoidal arteries, that the obstruction of the main trunk can affect it but little. When the primitive iliac has been tied the circulation must be restored by means of the communication which exists between the arte- ries of the upper and lower extremities through the internal mammary and epigastric arteries, of that between the aorta and the iliac arteries, through the intercostal, lumbar, middle sacral, hemorrhoidal, and the branches of the latter, and of that between the iliac arteries of both sides. For Bibliography, see Anatomy and Artery. (B. Alcock.) ARTERIA INNOMINATA, (in human anatomy) Fr. Tronc brach'w-cephalique. The innominata or brachiocephalic artery is situated to the anterior and right side of the thorax, extending from the arch of the aorta to the sterno-clavicular articulation. Of the three large vessels proceeding from the arch of the aorta, the innominata is the most anterior, the shortest, but of the largest calibre ; it takes its origin at a point corres- ponding and very nearly parallel to, the upper edge of the cartilage of the second rib almost immediately from that part of the arch of the aorta where it alters its direction from the right towards the left side, or rather from the com- mencement of what is termed the transverse portion of the arch, and hence the cause of its being at this point not only to the right side but also anterior and rather superior to the other two, which arise from the remainder of * Guthrie, t Harrison. J iVledico-Cliirurgical Transactions, vol. iv. the transverse division of the arch, the left carotid and subclavian arteries. It imme- diately ascends obliquely upwards, outwards, and very slightly backwards, to opposite the. right sterno-clavicular articulation, where it divides into the right sub-clavian and carotid arteries, the latter of which, although the smal- lest in diameter, appears from direction to be its continuation. The innominata, therefore, is but a short trunk, rarely exceeding from an inch and a half to two inches in length. Ne- vertheless instances are upon record in which it has attained above two inches and a half ; but these may be considered more in the light of anomalies than regular occurrences. We now proceed to consider the various re- lations which this vessel bears to the several important organs in its neighbourhood, and we shall then the more readily be able to account for the many distressing symptoms usually accompanying its enlargement. At its origin, it lies upon the trachea and at its division cor- responds, although at a considerable distance, to the longus colli muscle separated from it by glands and cellular tissue. Internally, or on its left side from below upwards, are the com- mencement of the left carotid artery and the trachea, the latter, however, lying upon a plane posterior to the artery, a quantity of cellular tissue and glands being usually met with between them. Externally or to its right the relations are more complicated and consist of parts of very great importance. It is here connected to the right pleura and the middle and inferior cardiac branches of the great sym- pathetic nerve; the internal jugular vein lies above it and on its right side, whilst the right brachio-cephalic vein is to its right but some- what anterior. Behind this vein and crossing the subclavian artery at right angles very close to its origin, we find the pneumo-gastric nerve entering the thorax and giving back its recur- rent branch which winds round the subclavian artery; still more externally is the phrenic nerve conducted into the thorax upon the an- terior border of the anterior scajpnus muscle, and between the two latter the internal mam- mary branch of the subclavian artery. The parts covering the vessel are studied with greatest advantage from the integuments back- wards ; and the best method of effecting this is as follows, as it enables us at the same time to take a clear view of the attachment of the various layers of the cervical fascia to the first bone of the sternum and the inter-clavicular ligament. Having placed the subject with a block underneath the shoulders, and the head hanging down, thus drawing the vessel as much as possible out of the thorax, carry an incision of about five inches upwards, commencing at the middle of the sternum opposite the carti- lage of the second rib. Through this incision carry another of the same length at right angles, commencing at the left sterno-clavicular arti- culation, and extending along the right clavicle as far as its centre. This crucial incision should merely divide the skin, the triangular flaps of which are next to be raised and re- ARTERIA INNOMINATA. 851 fleeted to the right and left, thus exposing a layer of fascia separating the skin from vthe platisma muscle ; this fascia is thin externally, but where it corresponds to the interval between the two sterno-mastoid muscles it becomes dense and more or less loaded with fat ; reflect this fascia and the platisma will next appear, behind which is that usually described as the superficial fascia of the neck covering the sterno-mastoid muscle, containing the external jugular vein, and increasing considerably in density above the sternum, over which it passes down in front of the pectoral muscles. Like the previous layer its thickness is augmented by fat. If this be raised the sterno-mastoid muscles and the first layer of the deep cervical fascia, extending between their two anterior margins, are brought into view, together with some small superficial vessels and nerves. This latter fascia should be carefully examined above the sternum to the anterior margin of which it strongly adheres ; it is very dense, so much so that if we endeavour to force a finger into the thorax at this point, it effectually resists our efforts. Behind this fascia is a space cor- responding in depth to the thickness of the upper edge of the first bone of the sternum, containing fat and usually a gland, and in ad- dition a vein rather larger than a crow-quill, extending across the neck about half an inch above the sternum; this communicates with a vein on either side of the neck running down on the anterior margin of the sterno-mastoid muscle, and should be carefully avoided by the surgeon in the operation for tying the in- nominata, as it is of sufficient size to cause embarrassment if wounded. If the fat and gland be now removed we come down upon the second layer of this fascia, which is also very dense and adheres to the inter-clavicular ligament. Having examined these parts and the triangular space existing between the sternal and clavicular insertions of the sterno-mastoid muscles, the sternal insertions of the latter should be detached and the first bone of the sternum removed ; this will expose the remains of the thymus gland and the sterno-hyoid and thyroid muscles, which being cut through and reflected upwards are found to cover the deep or third layer of the cervical fascia, which may be traced from the anterior scalenus muscle to its union with its fellow of the op- posite side, binding down the cervical vessels, &c. Upon removing this fascia we come down upon the arteria innominate covered by the following parts ; inferiorly the left brachio- cephalic vein passes nearly horizontally across the root of the artery to form the vena cava superior by uniting with the corresponding vein of the right side. Although the com- mencement of the vena cava, strictly speaking, has a closer relation to the arch of the aorta than the innominata, it is nevertheless sufficiently near the latter to render it of considerable im- portance in operations performed upon (hat vessel. Superiorly the first or upper cardiac nerve in its course towards the thorax crosses the innominata opposite its bifurcation ; we next observe the right inferior thyroid vein, which, emanating from the lower portion of the thyroid gland, and having formed with its fellow of the opposite side the thyroid venous plexus runs, obliquely downwards from the gland towards the right side directly in front of the innominata artery, and empties itself into the vena cava superior between the two brachio-cephalic veins. The middle thyroid artery, when it exists, may now be seen ascend- ing in front of the trachea. These several objects, viz. the left brachio-cephalic and thy- roid veins with the cardiac nerve, are all en- veloped in a quantity of loose cellular tissue and glands serving to connect them to the vessel, which may now be fully exposed and its different relations studied ; when we shall observe that on its right side there is a space bounded superiorly by the right subclavian artery, inferiorly by the left brachio-cephalic vein, to the right by the right brachio-cephalic vein, and to the left by the innominata artery itself ; this is the situation where the aneurismal needle should be introduced in the operation for tying this vessel, as we thus run less risk of wounding the veins. From the above description it is evident that the coverings of the innominata may be ar- ranged into ten layers, which, enumerated from the surface, consist of 1. The skin. 2. Layer of superficial fascia. 3. Platisma myoides muscle. 4. Superficial fascia. 5. First bone of the sternum, sternal ex- tremity of the right clavicle, sterno-mastoid muscle, with its accompanying vein the sterno and inter-clavicular ligaments and anterior layer of deep cervical fascia. 6. Cellular tissue, fat, containing large vein and a gland; the second layer of deep cervical fascia. 7. Sterno-hyoid muscle. 8. Sterno-thyroid muscle. 9. Third layer of deep cervical fascia. 10. Cellular tissue containing the first cardiac nerve, right inferior thyroid, and left brachio-cephalic veins, glands, &c. Arrived opposite to the right sterno-clavicu- lar articulation and to the interval between the sternal and clavicular insertions of the sterno- mastoid muscle, the arteria innominata usually divides into the right carotid and subclavian arteries. It rarely gives off any branches ante- cedent to its division, but a small third branch is frequently observed proceeding from it to distribute itself in front of the trachea, and ter- minate in the thyroid gland. Mr. Harrison, in his work on the Surgical Anatomy of the Arteries, has named it the " middle thyroid artery." The French anatomists give M. Neubauer the credit of discovering it, and consequently term it " l'artere thyroidienne de Neubauer " It is, however, as frequently given off from the aorta between the arteria inno- minata and left carotid. When we consider the relation which the in- nominata bears to the important organs sur- rounding it, we can scarcely be at any loss to account for the apparently remote symptoms present in aneurism of this vessel ; such, for instance, as oedema and blueness of the upper extremities, head and neck, cough, difficulty of breathing and swallowing, vertigo, failure 3 k 2 852 ARTERIA INNOMINATA. of sight, &c. Where the tumor extends to- wards the right side it presses upon the right brachio-cephalic vein, preventing the return of blood from the right arm and side of the head and neck ; if upwards in that direction the carotid and subclavian arteries become im- plicated, and consequent interruption to the circulation ensues ;. if forwards, the passage of blood is stopped through the left brachio- cephalic vein and the inferior thyroid venous plexus ; if to- the left, 'it encroaches upon the left carotid artery and trachea, whilst by en- larging backwards it acts immediately upon the trachea and mediately upon the oesophagus. Although the above facts are interesting, as serving to elucidate the various phenomena occurring in this malady, I fear that we must not attach too much importance to them as means of diagnosis, inasmuch as many, if not all, of the above symptoms may result from enlargement of other vessels and other causes, indeed we have only to turn to the admirable work of Mr. Allan Burns on the Surgical Ana- tomy of the Head and Neck, to be at once aware of the probability of deception in this respect. Anom'alies. — There are perhaps few arteries in the body which present so many varieties and anomalies as the innominata, whether stu- died with respect to its extent, course, situ- ation, or the number of brandies which it gives off. In the first place, it is frequently met with extending up into the neck as high as the thyroid cartilage before it divides into its ultimate branches, and sometimes lying in front of the trachea. It is scarcely necessary to remark in how great a degree this anomaly increases the difficulties and dangers attending the operation of tracheotomy. Secondly, the most remarkable variety occurring in the course of this artery is described by M. Velpeau, who, in his El^mens de Mcdecine Operatoire, men- tions three instances in which it passed to the left side in front of the trachea, and subse- quently wound from before backwards over this organ, returning between the oesophagus and vertebral column, to its usual points of division opposite the right sterno-clavicular articulation. Thirdly, the innominata is also occasionally irregular as to situation. It has been found arising from the centre of the trans- verse portion of the arch of the aorta instead of its commencement, and dividing into right and left carotid arteries, the right subclavian taking its origin from the spot usually occupied by the innominata. Again, instead of being placed on the right it has been met with given off from the left or posterior part of the arch dividing into the right and left carotids and left subclavian, in other instances into left sub- clavian and left carotid. Cases are also on record in which the innominata was altogether absent, the right carotid and subclavian arte- ries arising directly from the arch of the aorta. Fourthly, it is frequently anomalous in the number of branches it gives off. Occasionally the left carotid arises from it in addition to its usual branches, sometimes it divides into the two carotids instead of the subclavian and carotid; and Tiedemann mentions an instance where it gave off the right internal mam- mary. The considerations of the functions, size, and situation of the innominata,as well as its relations not only to the heart and aorta but also to the surrounding parts, at all times rendered the study of this vessel a subject of interest and impor- tance in the eyes of the operative surgeon; but it is comparatively of later years since Mr. Allan Burns first directed the attention of the profession to the fact that circulation through this vessel might be suddenly arrested without the functions of the brain, and power of the superior extremity being of necessity de- stroyed, that surgeons have been found bold enough to attempt placing a ligature upon it. There are three cases upon record in which a ligature has been placed upon the trunk of the innominata itself. The first operation was per- formed by Professor Mott, of New York, on the 11th of May, 1818. The patient died on the 26th day after the operation from repeated hemorrhage resulting from ulceration and yield- ing of the vessel. The second was by Professor Graeff on the 5th of March, 1829. The patient died on the sixty-seventh day after the operation from re- peated hemorrhage. The third was by Mr. Lizars at the Edin- burgh Royal Infirmary, on the 31st of May, 1837. The patient died on the twenty-first day after the operation, likewise from hemorrhage. This artery was likewise tied by Mr. Bland on the 25th March, 1832. The patient died on the 13th of April, three weeks after the operation. The following are the steps of the operation. The patient being placed in the horizontal po- sition with the shoulders raised and the head thrown back, make an incision of about two inches upwards along the anterior margin of the sterno-cleido-mastoid muscle of the right side, commencing at the upper edge of the sternum : from the inferior extremity of this carry another of similar extent outwards upon the right clavicle; these should divide the skin and subcutaneous tissue : next dissect this flap from below upwards and reflect it, exposing the platisma muscle ; cut through this muscle and the superficial fascia beneath it, and then care- fully detach the sternal insertion of the sterno- mastoid muscle and anterior layer of deep fascia, and should there not be sufficient space a portion of the clavicular fibres of the muscle. Having proceeded thus far, cut through the second layer of deep fascia, avoiding the vein already described as crossing this space, and subsequently divide the sterno-hyoid and thy- roid muscles upon a director; this will expose the third layer of deep fascia covering the vessel; a portion of this should be pinched up by forceps and an opening very cautiously made in it, after which, with the handle of a scalpel, clear the artery of its surrounding cel- lular tissue, draw the thyroid veins to the left side, the right pneumo-gastric nerve and in- ternal jugular vein to the right, and pressing the left brachio-cephalic vein downwards, carry the ligature obliquely upwards and inwards, or from the right to the left side, keeping it INSECTA. 853 close to tlie vessel to avoid implicating the cardiac nerves. Other plans of operation have been recom- mended, but the above appears to me to be the best, as it gives the surgeon room and oppor- tunity to see the state of parts through which he cuts, and enables him, if necessary, to tie either the subclavian or carotid, or both, with- out further trouble or inconvenience. It has been recommended to remove a por- tion of the first bone of the sternum ; but the idea will scarcely be entertained by any sur- geon possessing a proper knowledge of the parts, or who is competent to perform the operation. In the year 1827 Mr. Wardrop introduced a new method for treating aneurisms of the inriominata in imitation of Brasdor's plan of tying the vessel beyond the aneurismal tumour. He tied the subclavian artery, having found that the circulation through the carotid was very weak if not quite obliterated. The patient was a- Mrs. Denmark. The results of this case have been recorded as fa- vourable, but erroneously so. Mrs. Denmark died in the year 1829 of the same malady on account of which she underwent the operation. Altogether his example has been followed in six cases, with various results. In the first, Mr. Evans, of Belper in Derby- shire, in the year 1828, tied the carotid for aneurism of the innominata and commence- ment of the carotid. The patient recovered. In the second, M. Dupuytren, on the 12th of June, 1829, tied the subclavian for aneu- rism of the innominata. The patient died nine days afterwards. In the third, Professor Mott tied the carotid for aneurism of the innominata on the 26th of September, 1829. The patient recovered. In the fourth, Dr. Hall, of Baltimore, tied the carotid for aneurism of the inriominata on the 7th of September, 1830. The patient died five days afterwards. In the fifth, M. Morrisson, of Buenos Ayres, tied the common carotid for aneurism of the innominata on the 8th of November, 1832. The patient died twenty months afterwards. In the last, Mr. Fearn, of Derby, tied the carotid for the same complaint in the year 1836, the circulation through the subclavian being almost obliterated. Subsequent to the ope- ration the patient suffered from repeated at- tacks of bronchitis, with difficulty of breath- ing and cough upon the slightest exertion, so much so that on the 26th of July, 1838, she was again placed under Mr. Fearn's care. That gentleman concluding, after a careful ex- amination, that, in consequence of the circu- lation having been renewed through the sub- clavian artery, the previous operation had not cured the aneurism (which he now found im- plicated the commencement of the subclavian artery) determined upon placing a ligature upon this vessel where it passes over the first rib, and performed the operation on the 2d of August, 1838, apparently with complete success. Here then are the results of the two plans of operation hitherto performed in connection with the innominata. In Hunter's all the pa- tients were lost from repeated hemorrhage, although, as we have seen in one instance, the individual survived the operation above two months. Mr. Pattison, in his account of Mr. Mott's case, appears to attribute the loss of the patient to the fact of that gentleman's having commenced by exposing the subclavian artery, thereby depriving the vessel, of nourishment by the unnecessary destruction of the vasa vasorum ; this might in some degree have led to the result ; but I am more inclined to be- lieve that it occurred from other causes over which the surgeon unfortunately has no con- troul, I allude to the situation, origin, and direc- tion of the vessel itself. We have already ob- served that it arises from the commencement of the transverse portion of the arch of the aorta, and is consequently in adirect line withtheaorto- ventricular opening, being in point of direction the continuation of the ascending portion of the arch of the aorta. It thus receives the undi- minished impetus bestowed upon the blood by the contraction of the ventricle at a distance, barely of three inches ; hence, when a ligature is placed upon it, the force of the ventricle is directed more immediately upon this part of the artery, a coagulum can scarcely, if at all, be formed here, and the ligature being subjected to the constant efforts of the blood to overcome it, instead of ulcerating its way out, cleanly di- viding the vessels, produces inflammation and ulceration in its neighbourhood by constant friction, and thus gives rise to the fatal results. If I have here taken a correct view of the causes which have led to the fatal termination in all the cases where Hunter's method has been adopted, (and I have no reason to doubt having done so, as we learn from the accounts of the post-mortem examinations both in Mott's and Lizars' cases, that the coagulum was very imperfectly formed, and that extensive ulcera- tion of the vessel had ensued in the neighbour- hood of the ligature,) I am quite justified in adding that it is an operation which should never be performed unless in those cases where it presents the only chance of lengthening the patient's existence. This remark, however, does not apply to the plan introduced by Mr. Wardrop in imitation of Brasdor. Out of the seven cases in which it has hitherto been employed, and which I have here cited, three were successful, and of the other four one lived for a period of twenty months, and another (Mrs. Denmark) for about two years after the operation. ( H. Hancock.) INSECTA. — (ivropa.; Fr. Insecte; Germ. Insecten.) A class of Invertebrate animals, which, as constituted by Linnauis, formerly included several remarkable groups, which are now arranged as distinct classes. Besides the true Insecta these were Crustacea, Arach- nida, and Myriapoda. Modern naturalists have been almost unanimous in separating these groups from Insects, which, in their per- fect state, differ from them in being constantly Hexapods. Besides this very marked character, Insects differ from Crustacea in respiring atmo- 854 INSECTA. spheric air by means of ramified trachea? — from Arachnida in the body being constantly divided into a distinct head, thorax, and abdomen — and from Myriapoda, in the body being com- posed in general of thirteen segments. Insects, therefore, may be characterized as a class of hexapodous invertebrate animals, which possess antennae, and have the body com- posed of several segments, united into three and sometimes four distinct parts, articulated together, consisting of head, thorax, and abdo- men. They breathe atmospheric air by means of lateral spiracles and tracheae, and pass through a succession of changes of form, or shed their external covering before they arrive at their perfect state. They also possess other charac- ters in common with the Myriapods and Arach- nidans, as the circulation of the nutritive fluids by means of a pulsatory dorsal vessel, divided into distinct chambers or compartments, and the respiration of atmospheric air by means of spiracular orifices, and with the Crustaceans in being in general oviparous. Anatomically considered, Insects, as re- marked by Professors Grant* and Owen,f bear a remarkable analogy amongst invertebrated animals to Birds amongst the vertebrated. They constitute the most beautiful, most active, and most highly organized of any of the Inverte- brated classes. Like Birds, they are inhabi- tants of the air, the earth, and the waters, and the dominion of some of them is even extended to the bodies of other animals. Physiologically considered, they also resemble " the feathered tribes of air." Like them they have a more voluminous and extensive respiration, and a greater power of generating and of maintaining a higher temperature of body than any other class in the division of animals to which they respectively belong. The number of species is greater than is known in any other division of the animal kingdom, and is only exceeded, as in Fishes, by the almost countless myriads of individuals which every species produces. The metamorphoses which most of them under- go before they arrive at the perfect state, and are able to fulfil all the ends of their existence, are more curious and striking than in any other class, and in the greater number of species the same individual differs so materially at its dif- ferent periods of life, both in its internal as well as external conformation, in its habits, locality, and kind of food, that it becomes one of the most interesting investigations of the physiologist to ascertain the manner in which these changes are effected, — to trace the suc- cessive steps by which that despised and almost unnoticed larva that but a few days before was grovelling on the earth, with its internal organi- zation fitted only for the reception and assimila- tion of the grossest vegetable matter, has had the whole of its external form so completely changed as now to have become an object of admiration and delight, and able to " spurn the dull earth" and wing its way into the open atmosphere, with its internal parts adapted only * Lectures on Comp. Anatomy, Lancet, 1833-34. t See Aves, vol. i. p. 246. for the reception of the purest and most con- centrated aliment, now rendered absolutely necessary for the support and renovation of its redoubled energies. But this condition of insect life is greatly modified in the different families. Thus the most active species are diurnal insects, and are those which have the greatest development of the organs of locomo- tion, accompanied, as in birds of flight, by a more voluminous respiration, and a greater force and rapidity of circulation, and consequent muscular energy and necessity for a constant supply of food, as is well exemplified in the hive-bee and its affinities. But although many species are furnished with wings for flight, these organs are not universally met with in the species of every order, neither are they con- stant in the two sexes of the same species. In these instances it is always the male individual that is furnished with them. These exceptions occur among the beetles, as in the glow-worm ( Lumpyris, Jig. 335 & 336), in the Blattce or cock-roaches (Jig. 343), in some species of of moths ( Bmnbycida ), and in the plant-lice (Aphides ), while in other species, the ants, the individuals are furnished with wings only at a particular season of the year, and lose them immediately after the fulfilment of certain natural functions. In each of these instances, as noticed by Mr. Owen* in the ostrich and other birds unaccustomed to flight, the extent to which the respiratory organs are developed is in proportion to the habits of the species, being greatest in those of flight and least in those which reside constantly on the ground. Indeed, so varied are the forms, so different the habits and modes of life, that the division of Insects into families and tribes has afforded no small amount of difficulty to the scientific naturalist in arranging them according to their most natu- ral affinities, and hence a great variety of sys- tems have been proposed for this purpose, all of which perhaps are open to many objections. But it is not in the mere division of Insects into families and tribes that the philosophic naturalist meets with the greatest difficulty, but in assigning the situation which the whole class ought to occupy in the animal kingdom, both in regard to Insects themselves, and in their relations to other animals. Whether naturalists adopt as the basis of arrangement the development and perfection of the nervous system or that of the skeleton, with the organs of circulation and digestion, as compared with similar parts in other classes, they have usually been led to admit that while Insects are superior to many groups, which have been placed above them, in the former respects, they are inferior to them in the latter; and hence, although that portion of the animal body which is so all- important to active existence, the nervous system, is employed without hesitation as the fundamental type and principle of arrangement, and in the" vertebrated classes is scarcely ever departed from, it has become in the hands of many naturalists only of secondary importance in the invertebrated, and the greater perfection * See Aves, vol. i. p. 341. INSECTA. 855 of the circulatory and digestive organs in the molluscous classes has induced them to place these, which in other respects are inferior in development, above the Articulated. We cannot, however, agree with those who consider the organs of nutrition alone of sufficient im- portance to allow of this deviation from the fundamental principle of arrangement, neither can we admit with others that the nervous system of the higher Articulata is inferior to that of the higher Mollusks, the Cephalopoda, while we ourselves claim for the higher Articu- lata the most decided superiority in the next essential character of arrangement- — the deve- lopment of the skeleton and organs of locomo- tion. Without entering further upon this difficult subject, we will simply state our conviction with Carus, Burmeister, and others, that the articulated ought to stand at the head of the invertebrated classes, seeing that they contain among them some of the most completely organized of invertebrated animals. We shall reserve for the present our explanation of the steps by which we propose to pass from the lowest vertebrated forms to these, in our esti- mation, the highest of the invertebrated, and proceed to consider the arrangement of Insects, as a class, as proposed by different naturalists, before we enter upon an examination of the peculiarities of these animals. The principles upon which naturalists have attempted to arrange this interesting class have been almost as various as the systems proposed. Aristotle among the ancients arranged Insects with reference to the presence or absence of the organs of flight ; and although he was far more successful than many of his successors in separating from Insects the Crustacea, as a dis- tinct class, his arrangement of Insects is not entirely natural, since it separates some of the most nearly connected families. Among the moderns, Aldrovandus, in the beginning of the seventeenth century, divided them into land and water Insects, and subdivided these groups into families according to the structure of their wings and legs. Swammerdam many years afterwards first proposed to arrange Insects with reference to their metamorphoses ; first, those which undergo only a partial or incom- plete metamorphosis, and, secondly, those which undergo a true or complete one. The latter he again divided into those which undergo a slight change of form, but are active during the pupa state ; secondly, those which have distinct limbs but are inactive in that condition ; and, lastly, those which have no external development of wings or legs, but remain as inactive ovate pupa;. This was the first step towards arranging Insects upon a truly natural system ; since, as Messrs. Kirby and Spence have justly ob- served,* although the employment of the meta- morphoses taken alone leads to an artificial arrangement, it is of the greatest use in con- nexion with characters taken from the perfect Insect, in forming a natural system. Our illustrious countryman Ray, in the beginning * Introd. to lintomol. vol, iv. p. 442. of the eighteenth century, followed the example of Swammerdam in arranging Insects primarily according to their metamorphoses ; and Lister, in 1710, followed with a modification of Ray's classification, after which nothing further was proposed until Linnajus published the first edi- tion of his Systema Naturae in 1735. His arrange- ment was based upon the form and structure of the wings. By these he divided Insects into three groups. First, those wilh four wings, in which he included in three divisions those Insects which now constitute his orders Coleoptem, Ilemiptera, Lepidoptera, Neuroptera, and Hy- menoptera. In the second group he placed Insects with two wings, his single order Dip- tera; and in the third, Insects without wings, his order Aptera. In this arrangement, founded partly upon that of Aristotle, Linna»us was particularly successful in establishing some very natural series, although in including the Crus- tacea among his Aptera, like Swammerdam and Ray, he receded a little from a natural system. After Linnaeus, Degeer and Geoffroy each proposed a new arrangement, but it was not until an entirely new set of organs had been selected by Fabricius that Insects began to be arranged upon truly natural principles. The parts from which Fabricius drew his cha- racters were those of the mouth, by which he divided Insects primarily into two sections, the Mandibulated, or those furnished with jaws for comminuting their food, and the Haustelluted, or those which take their aliment by means of a flexible elongated proboscis, without distinct manducatory organs. But the difficulty of forming a strictly natural system still existed, so long as the characters employed were derived only from particular sets of organs, and not from a consideration of the whole. Cuvier, by founding his arrangement upon an examination of all the external organs, and thereby establish- ing natural families, advanced very far towards the object desired, and was followed by La- treille, Lamarck, Dumeril, Leach, Kirby and Spence, and MacLeay, who continued to im- prove the arrangement of the class. These have been followed by Messrs. Stephens and Curtis, and very recently by Mr. Westwood, the inde- fatigable Secretary of the Entomological Society, each of whom has proposed a different arrange- ment. But none of the systems hitherto pro- posed are entirely satisfactory, so great indeed is the difficulty of discovering the connecting links of families, which, distributed over the whole globe, are believed to include from 100,000 to 150,000 distinct species; and this difficulty will probably continue until the in- ternal as well as the external organization is better known in a greater number of insects than it is at present, and applied to their arrangement, as has lately been done by Bur- meister. In the succeeding pages we shall adopt the arrangement of Mr. Stephens, giving a synoptical view of the families, with the addition of some of the recently established foreign ones, and shall also add particular descriptions of some of the most remarkable, referring our readers for more minute descrip- tions of them to Mr. Stephens's admirable 856 INSECTA. " Illustrations,'' and also to the valuable work by Mr. Westwood, from which work we shall " An Introduction to the Modern Classifica- in part derive the characters by which the tion of Insects," now in course of publication different tribes are distinguished. Table of the Arrangement of Insects according to the System of Mr. Stephens. Class INSECTA. Sub-Class I. MANDIBULATA. CoLEOPTERA. Pentamera. Tribe 1. Adephaga. (Gluttons.) Tribe 2. Rypophaga. ( Cleansers.) Pentamera. Sub-tribe 1. Geodephaga. Predaceous ground-feeders. Cicindelidffi Tiger-beetles. Brachinidae Scaritida? V Carabidae, Jig. 329, Ground-beetles. Harpalida [ Bembidiidffi l_Elaphridae Sub-tribe 2. "\ Hydradephaga. f Diticidse Water-beetles. Predaceous i Gyrinidae Whirlgigs. water-feeders. J ("Heteroceridae I Parniidae Sub-tribe 3. Limniidae Phylhydrida. < Helophoridoe Water-lovers. | Hydrophilidae,^g. 330, Water-beetles. LSphaeridiidae Anisotomidae Sub-tribe 4. Necrophaga. Carrion-feeders. Helocera 1. Lamellicornes 2. 4 Scaphidids Silphidae, Jig. 331, Carrion-beetles. Nitidulidae Engidae Paussidaa, West. _Dermestidae { Byrrhidae Sand-beetles. \ Histeridae Dung-beetles. "Lucanidae Stag-beetles. Scarabaeidae Geotrupidae, Jig. 332, Dung-beetles. Aphodiidae Trogidae Dynastidas^/Zg.333, Rhinoceros-beetles. Rutelidae Anaplognathidas Melolonthidae Cockchaffers. Glaphyridae _Cetoniadaa Sun-beetles. Subsectio 3. *\ guprggtidgg Gold-beaters. Macrosterm, West. (Eu^nemidffi) WesL (panted sternum). ) E1^ridae,/g. 334, Springing beetles. rCebrionidas J Cyphonidae I Lampyridae Jtgs.335k,336Glow-worms I Telephoridae Sub-sectio 4. Aprosterni, West. Malacodermi, (soft skin.) Melyridas Tillidae Ptinidae Lymexylonidae Bostricidae _Scolytida2 Death-watches. Wood-borers. INSECTA. 857 Pseudo- Tetramera, West. o "Si v. OLEOPTERA. J seudo-trimera, '§ l West. £ ) C Pseudo Hetero-mera.S 4 Dermaptera. Ortiioptera. C Curculionidae fig. 337 Hog- Rhinchophora 1 . < Attelabidae, West. L Salpingidae beetles. Longicornes. Sub-sectio 2. Phytophaga, Kirby. { Eupoda 1. Cyclica 2. Trimeri 3. Brachelytra. Newroptera { Neuroptera. ■< Panorpina 1. Anisoptera 2. Libellulina 3. Temitina 4. Megaloptera 5. Trichopiera. {Cucujidae Priomdae Jig. 338 Gout-beetles. Cerambycidae Lepturidae Crioceridae r Galerucida? < Chrysomelidae^g. 339 (.Cassidae Helmet-beetles. C Coccinellidae Lady-Cows. < Endomychidae (.Hispidae Tenebrionidae Blapsidae Jig. 340 Pimelidae Helopidae Lagriidae, West. Melandryidae Horiidse, West. Mordellidae GCdemeridae Pyrochroida? Cantharidae Oil-beetles. Notoxid'ae JScydmEenidae fPselaphidas ~\ I Tachyporidae < Staphylinidae Jig. 341 f Rove-beetles. J Stenidae \_Omalidae Forficulidae Earwigs. f Gryllidae Grasshoppers. Locustidae Locusts. Achetidae Jig. 342 Crickets. Phasmadae Mantidae, Praying Insects. _Blattidae fig. 343 Cock-roaches. ( Boreidae I Panorpidae Jig. 344 Scorpion-flics. Ephemeridae Jig. 345 May-Jlies. % Agnonidae ) Libellulida3, Dragon-flies. ("Myrmeleonidae Lion-ants. j Hemerobidae J Psocidae j Raphidiidaa I Mantispidae, West. (JTermetidae, White Ants. f Sialidae ( Perlidae r Philopotamidae % Leptoceridae (. Phryganidae Caddis-fii 858 INSECTA. Hymenoptera. IIymenoptera. Stiiepsiptera. Terebrantia 1. Pupophaga 2. Aculeata 3. Tubulifera 4. s Tenthredinidre fig. 355 B. Saw-flics. -v Xipbydriidae C Uroceridae r Evaniidae J Ichneumonidae Ichneumon-flies. I Braconidee VAlysiidae •Formicidas Ants. Mutillidae Scoliidae Sapygidae Pompilidas Sand-wasps. Sphecida? Larrida? Bembecidas Crabronidaa Vespidae Jig. 346 Hornets 4" Wasps. Apidae Bees. "Andrenidaa Sand-bees. r Chrysididae Golden wasps. J Chalcididae j Proctotrupidas vXynipidas Gall-flies. Stylopidae fig. 347 Sub-Class 2. HAUSTELLATA. Lepidoptera. a Diurna 1. Crepuscularia 2. Pomeridiana 3. Nocturna 4. Semidiurna 5. Vespertina 6. r Papilionidae \ Nymphalid \ Lycenid vHesperi lidae -\ alidae f lae r idae J Butterflies. r Zygaenidas -\ ) ShS**' 348 [ Hawk-moths. CiEgeriidae s Hepialidae 1 Notodontidae ) Bombycidae VArctiidae < Lithosiidae \ Noctuidae C Geometridae < Platyptericidae C Pyralidae X Moths. { Tortricidae Ypuonomeutidas Tineidae Alucitidae Diptera. ("Culicidae Gnats. JTipulids Long-legs. Asilids fig. 349 Empidffi Dolichopidse Rhagionidas Mydasidas Tabanidae Blood-suckers. ^Bombylids INSECTA. 859 Diptera (contin.) homaloptera. Aphaniptera. Anthracidae Acroceridae Stratiomydae Xylophagidae Syrphidae Stomoxydae Conopidae CEstndae Gad-flies. Muscidae Huuse-Jiies, fyc. S Hippoboscida: fig. 350 Forest-flies. \ Nycteribidse Pulicidae Fleas. After a. Hem/ptera. Terrestria 1. _Aquatica 2. Homoptera. % Pediculids, Lice. \ Nirmidse Jig. 351 Bird-lice. ,-Cimicidae Bugs. Pentatomidae Coreidae Reduviidae Masked bugs. Acanthiidas ^-Hydrometridas Skip-jacks. Nepidae fig. 352 Water-scorpions. Notonectidae Water-boatmen. /-Cicadiidae fig. 353 Tree-hoppers. I Cercopidae J Psyllidae ] Thripidae I Aphidae Plant-lice. ^-Coccidae Class Insecta, (Insects.) Animal Invertebrated, hexapodous, under- goes metamorphoses. Body in general winged, and composed of seg- ments divided into three distinct regions. Skeleton external, formed of the dermal co- verings. ^nienntf two, respiration aerial, sexes distinct.' Sub-class 1. Mandibulata. Order I. COLEOPTERA. Wings four, anterior ones (elytra) hard, co- riaceous, covering the abdomen, divided by a longitudinal suture, not employed in flight; posterior ones usually jointed, with their apex acute. Metamorphosis complete. The Beetles constitute by far the most nu- merous and varied tribes in any order, and differ as much in habits and size as in general form. They include every variety of confor- mation and bulk from the minute but rapa- cious Staphylinidce, to the gigantic phytopha- gous DynastidcE and Cetoniida. So numerous are the species that, according to Burmeister,* there are 28,000 in the Berlin collection alone, while the whole that is known is supposed to exceed 36,000. In Mr. Stephens's arrange- ment they have been divided into families which amount to more than one-third of the whole class, and these families are grouped into six sections. The first section includes most of the predaceous beetles, and is divided * Manual of Entomology (Translation), p. 583. into two tribes, Adepliaga and Rhypophaga, and these are divided into four sub-tribes. The first sub-tribe, Geodephaga, includes the predaceous Ground-beetles, which are cha- racterized by the elegance of their form and alacrity of their movements. They have six projecting palpi,* their mandibles are strong, curved, and pointed, and their legs slender and formed for running, (fig. 329.) Some of Fig. 329. Carabiis monilis, ( Ground-beetle, male. ) * The third pair of palpi are maxillary, and arc the analogues of what we shall hereafter describe as the Galea. 860 INSECTA. this division, the Cicindelida, are extremely voracious, and most of them feed upon dead animal substances, although some of the Hur- palida are known to be vegetable feeders. The second sub-tribe, Hydradephaga, includes the predaceous water-beetles, and the third, Philhydrida, a variety of families allied to each other by similarity in general structure, by inhabiting water or damp situations, and by subsisting upon decaying animal and vegetable substances, fungi, &c. Amongst the aquatic species is one of the largest British beetles, Hydrous piceus (Jig. 330). Fig. 330. Hydrous piceus, ( Great water -beetle, male.) All the water-beetles are characterized by their four posterior legs being formed peculiarly for swimming ; they are ciliated along the tarsal joints, the last of which is furnished with a very minute claw. The insects of the third sub-tribe, the predaceous water-beetles, Dyti- cit&e, are distinguished from those of the second by the latter having long and slender instead of clavated antennae, and by their possessing six instead of only four palpi. The males of both sub-tribes have one or more joints of their anterior tarsi (Jig. 330, A.) very much dilated, by means of which they attach themselves strongly to the females. Their larva are active Fig. 331. and voracious. The fourth sub-tribe, Necro- p/taga, includes the carrion and burying-beetles (Jig. 331), so called from their habit of bury- ing small dead animals in the ground, by digging away the earth from beneath them, and thus allowing them to sink down, and then depositing their eggs in the bodies. The genera of this division differ considerably from each other, but may be characterized as in general possessing abruptly clavated antennas, an oval or oblong body, with the elytra often truncated, and the legs strong and formed for running. The second section is also divided into four tribes, which include insects of different habits and conformation. In the first tribe, Helocera, the insects are of an oval shape, and have the antennas geni- culated, and terminated by an oval club. Their legs are flattened, broad, and formed for burrowing, and are terminated by very minute tarsi. Their bodies are exceedingly hard ; they feed upon decaying animal matter, and when touched simulate the appearance of death. The second tribe, Lamellicornes, are a very natural group. They are distinguished by the club of the antennae being divided into plates or lamellae. Their legs are thick, strong, and deeply notched, and the tarsi of the anterior pair in some families are very minute. They are either stercoraceous or vegetable feeders, subsisting, like the common dung-beetle, Geo- trupes stercorarius* (Jig. 332), upon deeom- Fig. 332. Necropltorus vespillo, ( Burying-beetk J. Geotrupes stercorarius, ( Dung-beetle ). posing vegetable substances, or like the chaffer- beetles, Melolonthidcc, upon the foliage of shrubs or trees, or like the Dynastidisf * This drawing is of a specimen captured by the writer of the present article in the summer of 1829, and affords a curious instance of malformation of the anterior extremities with the tibias lunated and acuminated, without dentations, the tarsi entirely wanting. It is now in the cabinet of the Rev. F. W. Hope. t It is asserted that the Dyttastes Hercules grasps INSECTA. 861 (fig. 333) upon the sap that flows from the The third tribe, Macrosterni, Westw. in- wounded bark or roots. eludes a family of insects, Elaterida, (Jig. 334), Fig. 333. Fig. 334. Dynastes Hercules. , the epicranium ; b, the clypeus ; c, labrum ; d, mandibles •, e, maxilla and palpi ;/, labial palpi ; tympanum ; f t> socket for the an- tenna, covered with membrane ; dd, clypeus, anterior and posterior; *, lingua; »**, paraglossae. ( Other letters and Jiyures as in Hydrous. ) In the epicranium of Blatta (Jig. 373), the suture is almost obliterated, being only disco- verable by aid of the microscope, but on careful inspection it is seen to end at a point opposite to the middle of the superior portion of the corneas, where it forms the apex of the triangle, which enters, on each side, the anterior margin of a circular space covered with a tense mem- brane, the tympanum (f), which is situated, as observed by Treviranus, a little behind the in- sertion of the antennas. These organs are also inserted in a rounded space covered by a mem- brane. From these points the suture becomes obliterated, but seems to pass in the direction of the anterior boundary of the corneas to the base of the mandibles. The clypeus posterior (d) thus appears to form the greater portion of the front or face of the insect, and is united by a transverse freely articulating membrane, ex- tending across from the base of each mandible with a short transverse plate, the clypeus ante- rior (d ), which has hitherto been looked upon as the true clypeus. In the common green grasshopper, Acrida viridissima, the boundary of the posterior clypeus is at the most anterior part of the head immediately between the an- tennae, the suture extending, as in other in- sects, to their base. The clypeus anterior is a short transverse moveable plate, and is articu- lated with the labrum (e), which is also short, transverse, and freely moveable upon the cly- peus anterior. This moveable condition of the anterior clypeus and lip has not a little puzzled entomologists. Mr. Newman* has remarked that " the lip and shield move simultaneously * Op. cit. p. 9. 896 INSECTA. with the mandibles in mastication," and that " this is a departure from a general law of nature, and its occurrence is well worth re- marking; as the motion of the shield might in- duce an observer to suppose it the lip, which would consequently become a new and super- numerary elementary part." Thus, then, the motion of this part in Orthoptera is considered as an anomalous condition, but the same thing occurs in Coleoptera. In Dyticida, the cly- peus is freely moveable, as well as the labrum, and probably this mobility has reference to the rapacious habits of the insects. The inferior surface of the head in Orthoptera varies a little from the type of the Coleoptera, although it is formed, as in that order, of four distinct parts. The gtila, or basilar region ( m), which includes part of the occipital foramen, is a broad transverse plate, rounded at its lateral, and concave at its anterior and posterior mar- gins. In the mole-cricket, as in most of the beetles, the true gula is well developed be- tween the occipital foramen and sub-men- tum, and in that insect is of a trian- gular shape, with its apex directed backwards. Fig. 374. Under surface of mouth of Btatta. Figures as before. But in the Blattida (fig. 374, m ), the sub-men- tum and gula appear to have been closely united, without trace of their former distinc- tion, and the men turn (I) is short, transverse, and articulated with the palpiger and ligula (i). From the complexity of parts into which the ligula is divided, we consider it better, as before remarked, to omit any parti- cular description of the palpiger, which, Mr. Newman states, is situated between the proper ligula and men turn. In Blatta the ligula is divided into six distinct parts. To two of these (i) are attached the labial palpi, and they ap- pear to be the palpiger as described by New- man. From the upper anterior margin of these, nearest the median line, arise two short lobes, covered partly on their exterior margins by two larger ones, the paraglossaz (* *), which become of much importance in the mouth of Hymenoptera. In the mole-cricket the ligula is divided only into four lobes, all of which are exceedingly narrow, and very much resemble palpi. In some of the Locustida, the labium is simply divided in the median line a.s in Hydrous. The true ligula or tongue (Jig. 374*) in most of the Orthoptera is a soft projecting fleshy body, like the tongue of other animals, and is situated above the men- turn and sub-mentum, within the mouth of which it forms the floor and passage to the pharynx. In Blatta it is narrow and elon- gated, and projects as far as the middle of the ligula, and it is even more largely developed in the Locustida and Achetida. In the maxilla we recognise the same parts as in Coleoptera, with but little variation of form except in the galea and lacinia. The lacinia (5) is usually elongated, and furnished with a sharp hook bipid at its apex. In Achetidaz and most of the vegetable feeders it is strong and much bent at its extremity, but in the omnivorous Bluttidte it is also sharpened to a cutting edge along its inner margin. It is in this order of insects that the secondary appendage of the maxilla, the galea (6), is most fully developed, and covers the lacinia so completely as to serve the office of a shield or helmet. In the vege- table-feeding Locustida, this part is sometimes three-jointed, as observed by Newman* in Acri/dium, but usually it is simply an obtuse double-jointed organ, hollowed on its inner side; but in the Blattida it is expanded at its extremity into a thick oval bulb, or soft cushion, encircled with fine hairs, evidently well adapted for touching or feeling. In all the Orthoptera, but more particularly in the Blattida, the articulation of the maxilla with the sub-mentum is less compact than in the Coleoptera ; and this appears to be referable to the same circumstance as before noticed with regard to the mobility of the anterior clypeus, the voracious habits of the insect. Thus, to allow of very extensive motion to the parts, the stipes (2) is articulated at an angle with the cardo (1), and a broad muscular structure, at- tached along the inner border of the lacinia, as far as the base of its sharp articulated apex, upon which it acts, is interposed between the maxilla and sub-mentum, and forms part of the inferior boundary of the mouth. The mandibles in this order of insects, as remarked by Marcel de Serres,-)- are more perfectly constructed than in any other. In those which masticate their food, and devour large quantities of vegetable matter, as the Locustida, the mandibles are furnished both with cutting and grinding sur- faces. The anterior or apical margin is deve- loped into acute cutting teeth, somewhat like the canine teeth of vertebrata, while the inner and posterior part of the mandible is broad, flattened, and covered with elevated irregular ridges, like the teeth of some Herbivora, and is admirably adapted for grinding or chewing. This complicated structure does not exist in the more carnivorous species, the Blattida, in which the mandibles are arched, and indented with sharp triangular teeth (fig. 3TS,f), very closely resembling the cutting teeth of Carni- vore, and are articulated by strong condyles at the side of the head, on a line with the articula- tion of the clypeus anterior, and not so far back as that of the maxilla. The eyes in Orthoptera are usually exceedingly prominent and round, but not large, except in Blatta, in which they * P. 32. t Annales des Museums, No. xvi. p. 56. INSECTA. 897 are kidney-shaped, and are spread over a great part of the sides of the head. The ocelli, which are found in most of this order, do not exist in Blatta. They are very distinct in the Gryllida and Locustida, and also in the mole- cricket ; but it is remarkable, as Mr. Kirby for- merly observed, that they are not met with in the pupa or larva state of these insects. In the pupa of the mole-cricket there are simply two slightly elevated tubercles, in the situation in which the ocelli are afterwards developed. They thus appear to have reference to some particular condition of the perfect insect, al- though the habits of the three states appear to be similar. The antenna are organs of much importance, and are usually of considerable length, except in the carnivorous Mantida, or praying insects, in which they are very short. These insects, which take their living food by sight alone, have the shortness of their an- tenna?, the supposed organs of hearing, com- pensated for by the immense size of their large globular cornea?, situated at the superior angles of the head, so as to enable the insect to see in every direction. But in those which reside in the dark, or which seek their food by the aid of other senses, the antenna? are exceedingly long, and formed of an immense number of joints, especially in the Gryllida, Achetida, and Blattida, which are noted for acuteness of hearing. In the interior of the head the laminae squamosa are thick and strong, and are articu- lated, as in Hydrous, with the angles of the epi- cranial suture superiorly, and inferiorly with the lamina: posterior es, and the tentorium forms a distinct ring, as in Lucanus. In the Neuroptera we recognise the same elementary parts in the head and mouth as in the preceding Orders, but in this they are de- veloped into new forms. The epicranium, so conspicuous in the former, is reduced to its minimum in this Order, owing to the immense development of the organs of vision, which, attaining their greatest extent in (Es/nia gran- dis, are expanded over the whole of the upper and lateral surfaces of the head, and are ap- proximated together in the median line, leaving only the epicranial suture between them. A small portion only of the epicranium exists anterior to these great cornea?, but in that por- tion, as usual, are situated the ocelli; while the minute antennse, reduced also to their mi- nimum of size in these Libellulida, the most rapacious and insatiable of all insects, are still situated, as in Coleoptera, at the external angles of the suture. In the dilated anterior portion of the head we distinctly recognize the clypeus posterior and anterior, and below these the transverse cordiform lubrum, separated by su- tures, but freely articulated together as in Or- thoptera. At the lower concave margin of the clypeus anterior in CEs/ina grandis is a short triangular plate intervening between the clypeus and labrum, and articulating with both like a distinct segment; it is probably only part of the labrum. On the under surface of the head the gula and sub-mentum are indistinct, and merged as it were in the construction of three VOL. II. immensely dilated, doubly articulated plates, which cover the whole lateral and under sur- face of the mouth. The anterior portion of the middle plate, which in (Eshna is rounded at its anterior margin, is the true ligula, while the articulation behind it, from which arise the lateral plates, is the analogue of the mentum. The two lateral plates, composed each of two articulations, and in some species also of a third very minute one in the form of a short spine at the apex, we regard, with Brulle,* as the proper labial palpi immensely dilated. The mandibles concealed within the mouth are short, strong, and, in Libellula quadrimaculnta, arched. At the apex they are bifid, and armed with two sharp triangular teeth, and at their base with four sharp-pointed ones, excavated, and placed in different directions, adapted for crushing and cutting rather than for mastica- ting the food. Within the head they are arti- culated with portions of the epicranial and ba- silar regions, as in Coleoptera. The maxilla are long and prehensile. The true palpi are en- tirely absent, but the galea exists as an oblong articulated lobe, and the lucinia, which is arti- culated at its base and sharpened along its inner margin, as in the Blattida, is armed at its apex with four crooked sharp-pointed teeth, while the cardo is long, and articulated with the base of the maxilla at an angle, to allow of extensive motion, as in the maxilla of Orthop- tera. In other families of the Neuroptera, as in the Panorpida, the organs of manducation are small, but the anterior part of the head is elongated into a rostrum, occasioned by the narrowing and extension of the clypei, as we have before noticed in the Curculionida, while in the Phryganida, which take no food in their perfect state, the parts of the mouth are almost atrophied. In Hymenoptera the mouth assumes an en- tirely new form, but the changes in it are con- fined to the maxilla? and labrum, which are soon to become its chief organs. The head, placed vertically on the thorax, is still well de- veloped. The epicranial region is large, and extends very nearly to the insertion of the antenna? on the front. In most species it is densely covered with hairs, and the ocelli (fig. 375, b,) which are constant in this class, are usually arranged in a triangle on its most ver- tical part. The cornea (c) are large and kid- ney-shaped, and cover part of the lateral sur- face of the head, leaving between them a broad front, occupied by the clypei (d) and part of the epicranium. But in the males of the luve- bee, which come abroad only in the brightest sun-light in quest of the female, this space is diminished, and the cornea? are expanded over part of the front, and the whole of the epicra- nial region, as in the Libellula; the most ex- tensive vision being required by these insects, to enable them to discover the object of their solicitude, as by the other in the pursuit of its prey. In some of the pollenivorous and pre- * Annal. Soc. Enlom. de France, torn. ii. p. 343. 3 N 898 INSECTA. Fig. 375. Anterior and inferior views of the mouth and head of Antliophora return. A, antenna ; b, epicranium and ocelli ; c, cor- nea •, d, clypeus anterior ; e, labrum ; f, mandi- ble ; g, the maxilla; h, its palpus; i, feeler- bearer or part of the ligula ; It, labial palpus ; /, mentum; m, sub-mentum; 1, cardo of the maxilla ; 2, stipes ; 5, the lacinia or blade ; *, ligula; **,pa- raglosscB, its lateral lobes. daceous genera, the Tenthredinida and Ves- pida, the clypeus posterior seems to have be- come entirely obliterated, unless we regard the broad clypeus in these insects, as in the Hornet, the posterior one, and the plate concealed be- neath it, within the mouth, to which the labrum is attached, as the anterior. But we are not inclined to do this, because in some of the Ichneumonida and Sphecida a trace of the clypeus posterior remains a little anterior to the antennae. In Ichneumon Atropos the clypeus is narrowed and depressed in its middle, as if originally formed of two parts, while in Ammo- phila vulgaris the clypeus posterior is clearly indicated as a minute triangular plate situated in the middle line, immediately beneath the insertion of the antennae, and it exists in a similar form in some of the Apidct, as in the large female Bombus lapidarius, and in some specimens of Anthophora, the clypeus posterior being in all instances bounded by a trace of the triangular suture. The labrum (c) is always distinct, but variously formed. In Vespida it is narrow, acute, and hidden beneath the ante- rior clypeus; in the leaf-cutting bees, Mega- chile, it is narrow and quadrate; but in the hive and humble-bees it is large, and rounded at its anterior margin. The mandibles are sub- ject to considerable variation of form.* In * See Essay on Fossorial Hymenoptera, by W. E. Shuckard, p. 12, et seq. some, as in Ammophila, which burrows in the sand, they are long, hooked, and furnished with but a single tooth at the apex, without cutting edges ; and they are of somewhat the same form in Anthophora (fig. 375,/), whose habits of life in this respect are similar. In the Vespidie, which gather the materials for their nests by rasping off little packets of fibres from decaying wood, they are broad, triangular, and armed along their edges with strong teeth ; and such is also their structure in Anthidium mani- catum, which scrapes off the down from the woolly stems and leaves of plants for the same purpose; while, in the hive-bee, which em- ploys them in moulding the soft wax in the construction of the combs, they are shaped at the apex like a spoon, without indentations ; their form in each instance being thus dis- tinctly referable to the habits of the insects. In the gregarious species there is also a dif- ference in their form in the two sexes, those of the males being often smaller and less curved than of the females, or workers, and they are always, particularly in the Bombi, more densely covered with hairs. In the whole of the Terebrantia, Pupophaga, and some of the Aculeata the mandibles are still the chief cibarian organs ; the Athalia em- ploys them in masticating the pollen of flowers, and the maxillae and labium in sipping the honey; while the omnivorous Formicidce and Vespidte employ them in tearing and masti- cating their food, whether it be the pulpy sub- stance of fruits, or the muscles and hard cover- ings of other insects. In the Apidce. the chief use of the mandibles is in constructing the nest, while the maxillae and labium are the only organs employed in taking food. In the strictly carnivorous families the maxilla are not longer than in the preceding Orders. In most of these, as well also as in the Terebrantia and Chri/sidida, the extremity of each maxilla is obtuse, and divided into a distinct lacinia and galea, and the palpi are long and six-jointed. In the Formicidce and Vespidce, which subsist upon fluid as well as solid aliment, their length is increased ; but in the true Apidce, which subsist entirely upon honey, they are drawn out to a great length, and, with the labium be- neath, form a tube through which the aliment is conveyed to the mouth, as in the hive and humble-bees. In these species the cardo (1) is long, slender, and formed of two parls, which conjointly articulate with the stipes (2). The longest of these, the basilar portion, has two apophyses at its extremity, and is articulated with the anterior part of the base of the cra- nium, at the inner side of the articulation for the mandibles, exactly as in Coleoptera; and its muscles in like manner are attached to the lateral and inferior parts of the head and orbital plates. It is the lora, or lever of Kirby, which enables the insect, by the additional articula- tion of its second part with the sub-mentum, to thrust out the maxillae and labrum together to a great distance. The part that articulates with the sub-mentum, the proper cardo of Kirby, is very short in Bombus lapidarius, but of consi- INSECTA. 899 Fig. 376. Lateral view of the mouth of Anthophora. Letters and figures as before. 12, the lingua, or tongue. derable length in Anthophora. In each in- stance it is broadest at its articulation with the stipes, and, passing backwards diagonally, unites at its extremity with a corresponding part of the opposite side, and the two thus joined articulate with the narrow sub-mentum, the fulcrum of Kirby. The stipes forms the lateral basilar part of the maxilla, and is shorter in Anthophora than in Bombus, in which it is about one-third of the length of the maxilla. The palpifer is also distinct (3). The lacinia (5) is of great length, and gradually tapers to its extremity. Internally it is slightly concave, and externally is covered with a few scattered hairs. It is articulated freely with the stipes and palpifer, upon which it is inflected in a state of rest to form a sheath for the labium, when the parts of the mouth are folded. When the maxillae are extended to form the sucking tube with the labium, they are a little separated at their base, and inclose between them the cavity of the mouth, within which is a soft fleshy body, the lingua (12) or true tongue, situated anterior to and serving as a valve to the pharynx. The sub-mentum (m) is articulated by a single joint with the united extremities of the two cardines (13). It is long and narrow in Anthophora, but short and triangular in Bombus. It is attached at its sides by a fine membrane to the under surface of the head and throat. The mentum (I) articulates with the sub-mentum, and is an elongated rounded plate, which forms internally a channelled passage to the pharynx. Within it are inserted the muscles of the labial palpi (/c). These organs are long and styliform, and arise from a space at the base of the ligula, the part described as the palpiger by Newman. Their great length is occasioned by an excessive elongation of the second basial joint, which is sometimes as long as the whole maxilla itself, and is furnished at its distal extremity with a minute brush of hairs, and also articulates with the remaining short joint of the organ. The remaining por- tion of the labium is divided into three parts* The two lateral ones are short styliform pro- cesses, the paraglossa (**), and the central one, commonly called the tongue of the bee, is the part employed by the insect in gathering honey. In Apis, Bombus, and Anthophora it is a long tapering muscular organ, formed of an immense number of short annular divisions, and densely covered throughout its whole length with long erectile hairs. It is not tubular but solid, and when actively employed is extended to a great distance beyond the other parts of the mouth, but when at rest is closely packed up and con- cealed between the maxillae. The manner in which the honey is obtained when the organ is plunged into it at the bottom of a flower, is by lapping, or a constant succession of short and quick extensions and contractions of the organ, which occasion the fluid to be accumulated upon it, and ascend along its upper surface, until it reaches the orifice of the tube formed by the approximation of the maxilla above, and the labial palpi and this part of the ligula below. At each contraction a part of the ex- tended ligula is drawn within the orifice of the tube, and the honey with which it is covered ascends into the cavity of the mouth, assisted in its removal from the surface of the ligula by the little brush of hairs with which the elon- gated second joint of each labial palpus is fur- nished. From the mouth the honey is passed on through the pharynx into the oesophagus by the simple act of deglutition, as in other ani- mals. In Anthidium the ligula is not longer than the labial palpi; while in the Andrenida: all the parts of the mouth are much shortened, and resemble similar parts in the Vespidce in being divided into four lobes* In the latter insects the ligula is quadrifid, and is dilated at its apex, and each lobe is terminated by a minute gland.f The two lateral lobes, para- glossaz, are shorter than the middle ones. In Tenthredinida the ligula is also short, but is divided only into three lobes. We have thus seen that the head and its ap- pendages are most perfectly developed as a whole in the Coleoptera, and that in passing through the succeeding Orders of Mandibulata certain parts are more or less developed in each Order, in accordance with the general habits and mode of life of the insects ; that in the carnivorous and omnivorous families, and in those whose habits of life require a great amount of strength, either in procuring their food or in the construction of their nests, the mandibles are the most important of the oral organs, and are most largely developed. But as we pass from insects with these habits to the Haustellata, whose food and modes of life are of an entirely different description, the man- dibles lose their importance, and become atro- phied, and their office, now altered in its cha- racter, is performed by the maxillae and labium, 22. Newman. Paper on the Head of Insects, p. t Curtis. Westwood. 3 N 2 900 INSECTA. the development of which, in the higher forms of insects, is only of secondary importance, com- pared with that of the mandibles, but is now carried to so great an extent that these organs become almost or entirely the sole means of taking food. Not only do these changes take place in the parts of the mouth, but the whole head undergoes a similar alteration in the rela- tive form and size of its parts, occasioned by the excessive development of the organs of vi- sion. Thus in the Lepidoptera, (Jig. 377,) the Fig. 377. The head, and parts of the mouth of Sphinx Ugustri. A , antenna ; b, epicranium , c, cornea ; d, cly- peus posterior; e, labrum; f, mandible; g, max- illa or proboscis ; h, maxillary palpus; B, base of the maxilla with the mandibles and labrum; C, lateral view of the same. lateral and a large portion of the inferior surface of the head is entirely occupied by the cornea? (r), which are also extended far forwards upon the anterior. The occipital region is confined to the flat surface that is approximated to the prothorax. The epicranium (6) is distinct, and, as in the preceding Orders, extends as far an- teriorly on each side as the base of the antennae between the corneas, but the suture that sepa- rates it from the clypeus posterior (d) is almost transverse. The clypeus posterior is very large, and occupies the whole of the space between the corneas, on the front of the head. It is convex as in Neuroptera, and is narrowest at its inferior part. The clypeus anterior appears to exist in the form of a minute transverse plate, a little elongated in its middle on the hinder part, and separated by a transverse groove on its anterior from a much smaller plate, the labrum (e), with which it is consolidated. This part, which was first detected in Lepidoptera by the accurate Savigny,* is also a small convex transverse plate with a little triangular scale at its anterior margin, fitted closely to the front of the max- illa?. In Sphinx Ugustri, ( fig. 377,) the separa- • Memoires sur les Animaux sans Verttibres. tion of the labrum by suture from the part which we regard as the clypeus anterior, is distinct, but it appears to have been overlooked by Sa- vigny and others. On each side of the labrum are the rudiments of the mandibles ( /"). They are two minute, triangular plates, attached in part to the labrum and margin of the clypeus, to which, as Savigny has remarked, they appear to be soldered. They are applied to the base of the maxillae, and in Sphinx appear each to be formed of two parts, and are co- vered along their inner margin with stiff hairs. They are the remains of the large corneous mandibles of the larva. We are indebted for their discovery to the indefatigable researches of Savigny, who first traced their identity. The labium, which forms so conspicuous a part of the mouth in the preceding Orders, like the mandibles, is reduced to insignificance in this. It is a small triangular plate, closely attached to the under surface of the head, at the base of the maxillae, and its division into parts, so dis- tinct in other insects, is now scarcely perceptible. The labial palpi (k) arise one on each side of the labium. They are usually long, hairy, and three-jointed, and are reflected on the front of the head. Next to the maxillae they are the most conspicuous parts of the mouth, particularly in Fyralidte and Tortricida, in which they are long and pointed. The lingua has been sup- posed to be entirely absent in Lepidoptera. It was not detected by Savigny. Latreille be- lieved it to exist in the suture at the floor of the mouth, but Mr. Newman has observed a small mammiform protuberance in Sphinx li- gustri which he regards as the analogue of the tongue in this Order. The labrum, mandibles, and labium are entirely concealed by the re- flected labial palpi and a dense clothing of scales, and are only observed when the anterior part of the head is completely denuded of these coverings. Their atrophied condition affords a beautiful illustration of the law that in proportion as the functions of an organ be- come suspended, or are rendered unnecessary by the employment of other parts, the organ itself becomes wasted and utterly useless, and perhaps entirely disappears. Thus in those Lepidoptera whose food is liquid honey pro- duced in the deep chalices of flowers, the short mandibles of the voracious herbivorous larva would be entirely useless to the perfect insect, and its food would be inaccessible to it. Accordingly we find that the man- dibles are now unimportant organs, and the office of conveying food to the mouth is performed solely by the maxillae (), is a much broader and very distinct corneous plate, and may be regarded, perhaps, as the most important division ot the meso-notum, since it is to this that the ante- rior pair of wings, the elytra, are articulated. It is followed by the scutellum (3 c), which also is a very important division. Like the scutum it is a broad piece, that covers the pos- terior part of tire meso-notum, and extends on each side to the base of the elytra, the ulula, which arc continuous with them, being •attached to its margin. It is developed in the middle line into a remarkable elevated plate, that is shaped like an armorial shield, and •is so exceedingly large in some species, that it covers nearly the whole of the body. In Dyticus, and most of the Coleoptera, it is the small triangular plate which is situated be- tween the elytra, at their base, and is supposed to be of use in keeping these organs steady during flight. The fourth and last piece of the meso-notum, the post-Hcutelktm (3 d), like the prse-scutum, is narrow and inconspicuous. It is situated immediately behind the scutellum, and is the posterior boundary of the meso- notum. These parts together form the dorsal surface of the first wing-bearing segment, which is developed to as great an extent on its tinder as on its upper surface. The meso- notum is most fully developed in those insects in which the anterior pair of wings are the largest, as in the Lepidoptera, Ilymenoptera, and Dipteia, while in those in which the chief organs of flight are the posterior wings, as in the Coleoptera, it is the smallest of the three thoracic segments. The mew-sternum (fig. 385, A), like the pro-sternum, is formed by a strong middle piece, the proper sternum of the seg- ment, (3 g,) which is developed laterally into two processes, behind which the coxae of the middle pair of legs are articulated, and anteri- orly and laterally the episterna (3 /') and epi- mera (3 h). Each episternal piece is a broad elongated plate, which forms the anterior part of the meso-sternum. It is attached to the ante- rior margin of the lateral sternal process, so that its actual position is a little altered, the corresponding part of the pro-thoracic segment being situated behind the process of the sternal piece. This is a circumstance which occa- sionally takes place in the development of every part of the skeleton, the actual position of one part being altered by the greater or less de- velopement of another, while the relative posi- tion of each part always continues the same. Thus, although the episternum is situated more anteriorly in the meso- than in the pro-sternal surface, it still continues to be articulated with the sternum. The epimeron (3 A) is situated behind the episternum. It is a narrow elon- gated plate, that forms the posterior portion of die meso-thorax, and is united to the anterior of the meta-thorax. At its superior extremity it is much broader than at its inferior, which is articulated with the extremity of the sternal process, and also with the coxae of the middle legs. At the anterior border of the episternum there is a verv narrow but distinct plate, the parapteron (3 e). This piece, which is con- nected especially with the wings, undergoes a great change of form and size in the different orders. In the Coleoptera. it is narrow and evanescent, but as we shall hereafter see, is largely developed in the Lepidoptera. It is evidently a normal portion of the skeleton, but has only been described by Audouin as found in the meso- and meta-thoracic segments. We have before alluded to the existence of two detached pieces in the connecting membrane of the pro-thorax and head, which we regard as the analogues of these pieces of the meso- and meta-thorax. If this be correct, the relative position of these to the other parts of the pro- sternum is precisely similar to that of the same parts of the meso-stemum. The medifurca, (3 s,) or ento-thorax of this segment, is at- tached to the internal surface of the sternal piece, as in the pro-thorax. It is formed by two ascending rami, which are larger and longer than those of the pro-thorax, but like them are developed into two expanded por- tions, which are approximated together and form an arch, under which the nervous cord passes in its course to the meta-thorax. Fig. 386. A ^ 4-a Parts of the meta-thorax. ( Audouin.) A, meso-sternum ; 4 a, prae -scutum ; 4 b, scutum ; 4 c, scutellum ; 4 d, post-scutellum ; 4 e, parapteron ; 4f, episternum ; 4 g, meta-sternum -, 4 h, epimeron ; 4 3, post-furca. The meta-thorax (fig. 386) is the fourth seg- ment of the body, and the third of the thoracic region. Its upper surface, or meta-notum, as in the preceding segments, is divided into four portions. The pra-scutum (4 a) is a narrow transverse plate, which is bent down at its ante- rior margin like the prasscutum of the meso- notum, to form the meta-phragma, and is ex- tended on each side as far as the paraptera, bounding the insertion of the wings. In the middle line it is extended backwards upon the dorsal surface as far as the scutellum, thus di- viding into two parts the second piece, the scutum, (4 b,) which, like the corresponding part of the meso-notum, is connected with the 3 o 2 916 INSECTA. wings of the segment. This connexion is the great characteristic of the scutum in all insects. The next piece, the scutellum, (4 c,) is a much broader plate, and is extended across the whole surface of the meta-notum. Like the corre- sponding piece of the meso-notum, it bears on the middle line an excavated shield-shaped plate, and is connected at its external margin with the borders of the wings. The last piece, the post-scutellum, ( 4 d,) which, although nar- row like the prsescutum, is a strong horny plate that extends on each side, and like the scutel- lum, is connected with the wings. Its posterior margin is bent down to assist in forming the division between the thorax and abdomen, and is connected with the remains of the atrophied fifth segment. The meta-stemum (A) is fre- quently the most developed portion of the meta-thorax, particularly in those insects which, as Audouin has observed, are especially walkers. In Dyticus, the middle piece, the proper sternum (4 g), is a smooth expanded plate, which is produced at its anterior part into a spine, that articulates with the emarginated extremity of the crest of the meso-stemum. On each side of the spine it is developed into a broad, smooth, triangular plate, to the anterior border of which is articulated the episternum, (4 /',) also of a triangular form. This piece oc- cupies the anterior lateral region of the meta- sternum, and the parapteron, (4 e,) which is situated immediately beneath the insertion of the wing, is articulated with its superior border. The epimeron (4 It) of this segment is exceed- ingly small, and appears at first to be removed from its proper situation, being carried upwards to the side of the body by the enormously ex- panded coxa (/). But although removed from its usual situation, and reduced in size, it still retains its characteristic distinction, that of arti- culating with the coxa, and also with the tro- chuntin (?), (/c,) which, although minute, is in connexion both with the coxa and epimeron. The mcta-j'urca, or ento-thorax of this segment, (4 s,) is an exceedingly large and important piece, shaped like the letter Y. It is attached at its posterior extremity to a thin vertical plate, which is situated between the united coxte of the legs of this segment, and it is also arti- culated with the posterior part of the internal surface of the meta-sternum. From this at- tachment it is extended upwards and forwards into the middle of the meta-thorax, where it is expanded on each side into two broad curved plates, to which the muscles of the posterior legs are attached. In the middle line it is grooved, and at its' anterior part forms a par- tially covered canal, along which the nervous cord is transmitted in its course to the abdo- men. Besides the parts now described, there are also two curved plates reflected inwards from the posterior margin of the meta-sternum, where it is articulated with the coxae, and also one central vertical one, which arises in the me- dian line from the interior surface of the ster- num, and which appears to be the proper inte- rior sternal ridge. Each of the posterior coxa; is also furnished with a broad plate, which is situated within the meta-thorax, on each side of attachment of the post-furca. These parts rd attachments for the muscles of the legs. Fig. 337. Skeleton of Hydrous piceus. A, pectoral surface ; B, dorsal surface •, 2, pro- nation ; 2 a, prosternum ; 2 /, episternum ; meso- INSECTA. 9-17 notum ; 3 a, prsescntum ; 3 6, scutum; 3 c, scutcl- luin; 3 d, post-scutcllum •, meso-sternum; 3 g, ster- num ; 3 /(, episternum ; of, epimeron ; 3 i, crest of the meso-sternum ; 3 e, parapteron ; 3 It, trochan- tin ; 4, meta notum ; 4 a, praescutum ; 4 i, scu- tum ; 4 c, scutellum ; 4 d, post-scutellum ; 4 e, parapteron; meta-sternum ; 4 f, episternum; 4 g, meta-sternum ; 4 h, epimeron ; 4 i, crest of meta- sternum ; 4 It, trochantin (?) ; 4 I, coxa ; 4m, tro- chanter ; 4 n, femur ; o, tibia ; p, tarsus ; q, un- guis. These segments constitute the proper thorax of the insect, and the parts we have described are found in nearly all the Coleoptera, the most perfect species ; although, as before stated, they are sometimes greatly modified in shape, and varied in size and position, in order that the body of the insect may be adapted to its pecu- liar hubiis. Thus in the great water-beetle, Hydrous pictus, (Jig. 337,) which in its general appearance and mode of life very nearly resem- bles the Di/ticus, and not only burrows deeper into the mud at the bottom of stagnant waters, but is also accustomed to float among the weeds on the surface to bask in the sun, the form of the sternum is admirably adapted to its habits. The sterna of the meso-thorax and meta-thorax are not only both armed with a strong keel like a boat, but the two are firmly articulated together, which enables the insect more securely to float on the surface of the water, and thus afford additional strength to its whole body for the accomplishment of its ob- ject. But in the Dt/ticus, to which it is of the utmost consequence to be able to swim with the greatest rapidity, and turn with facility in the water, in the pursuit of its living prey, the pro-sternum and meso-sternum only are slightly keeled, while the meta-sternum is smooth, and the sides of the body are acute, and offer the least possible resistance to its movements. In addition to this, to afford suf- ficient strength to the body, together with faci- lity of motion, the sternum of the meta-thorax is produced in front into a short spine, which is inserted into a notch in the posterior part of the meso-sternum ; while the coxse of the poste- rior pair of legs upon which the chief efforts in swimming depend, although enormously en- larged to afford sufficient space for the inser- tion of the muscles, are flat and smooth like the rest of the under surface of the body, in order that they may not oppose the slightest impedi- ment to the motions of the insect. The different forms of the coxse (/) and of the acetabula(4 /c), into which they are inserted, have also a refe- rence to the habits of the species. The large posterior coxa? of the Vj/ticus are immoveably united by suture to the posterior margin of the meta-sternum, because, in this insect, the pos- terior pair of legs being especially designed for swimming, and their motions consequently being almost wholly in one direction, addi- tional strength is afforded to these organs by the immobility of the eoxse. In the Hydrous, in which all the legs are employed in walking, as well as in swimming, the coxaj are freely articulated in their respective acetabula, and each one is supported in part by the tro- chantin (?), (A), which is more developed than in the other insect. The strength of the body depends much upon the size of the thoracic segments, and the firm- ness of union which exists between them. Thus in those species which are more especially em- ployed in walking, in flying, or in swimming, the meso- and meta-thoracic segments are the largest. If the insect be aquatic, the largest parts, as we have seen, are the sternal surface of the meta-thorax, and its coxa? ; but if, on the contrary, the habits of the insect be aerial, then the dorsal surface of the segment is larger than the sternal. In those insects which are mostly employed on the ground in running or walking, as the Carabida, Geutrupida, Coprida, and Lucanidte, the meso- and meta-thoracic seg- ments are often anchylosed together, to give greater strength to the whole body. This is particularly the case in Lucunus cervus (Jig. 388), in which the small sternum of the meso- thorax (3 g) is firmly auchyclosed to the enor- mously enlarged sternum of the meta-thorax. The reason for this is not merely to afford greater stability to the meta-thorax and its wings, upon which entirely devolves the labour of supporting this unwieldy insect during flight, but also to give greater strength to the whole body, during the efforts of the insect to strip off the bark from the smaller roots and branches of trees, to obtain a flow of the juices upon which it subsists. That such is the reason for this anchyclosed condition of its segments is evident from the circumstance, that it occurs not only in those insects which require great muscular power during flight, but also in those which are much accustomed to laborious efforts in tearing, in burrowing, or in running. In these, also, the acetabula (2 r, 3 r), are exceed- ingly deep, and almost entirely enclose the coxae within them, so that while the limb can be rotated freely in almost every direction, a dislocation of it is utterly impossible. The ace- tabula are situated on each side of the poste- rior part of the sternum, in each of the three thoracic segments, and in general are formed by an approximation of the sternum and epi- meron, and sometimes, also, of the epister- num, as in the Dyticus (Jig. 384, A). When, as in this instance, the episternum enters largely into the formation of the acetabulum, the epimeron is carried backwards, and forms the postero-lateral boundary, the episternum the antero-lateral, and the sternum the anterior boundary, so that the acetabulum is formed by the junction of three articulating sutures, and completely surrounds the coxa. This consoli- dation of parts gives an amazing increase of strength to the segment in which it occurs, and is one of the circumstances which enables the insect to exert a degree of muscular power which is sometimes truly astonishing. It oc- curs in general in the pro-thoracic segment, as in Lucanus, (388, 2,) Geotrupes, Ateucltus, and other Lamellicornes. A similar condition of the acetabula of the meso-thorax exists also in the same insect (3r). But instead of the posterior wall of the cavity being formed by the epi- 918 TNSECTA. Fig. 388. Internal skeleton of Lucanus cervus. meron, it is formed by a reflection inwards of part of the anterior margin of the meta-sternum, (4 ) passes backwards beneath the greater rectus, and divides into two branches. The anterior one (y) is distributed to the four oblique mus- cles, and to the external or under surface of the rectus, which, as we shall presently show, is supplied on its internal surface from the transverse nerves (/). The second division passes backwards and is given, one portion to the under surface of the smaller rectus, and the other to the great oblique, while the ter- mination of this portion (w) is continuous with a filament of the second branch of the trans- verse nerves (/). Some branches from this nerve pass between the triangular and second oblique muscles (x), and others are given to the latero-abdominal. The second branch (q) of the great moto-sensitive nerve passes be- neath the great oblique, and gives off branches to the transverse abdominal muscles (y), and the latero-abdominal (z), while another sup- plies the latero-abdominal (31) and the oblique constrictor of the spiracle (25), and then di- vides into two portions, one of which is given to the retractor valvule (27), and the other to the transverse lateral muscles (24). The divisions of this branch of the moto-sensitive nerve are particularly interesting. Before dis- secting these nerves we had supposed that the constrictor of the spiracle (25) and the retractor of the valve (21) were supplied by the transverse nerves, and hence were surprised on finding that their nerves were derived from the great moto-sensitive of the gangliated cord, INSECTA. 947 by which it is presumed they are thus endowed with voluntary power and sensation. But on reflection it will appear that this ought really to be the case. To enable the insect to make a forcible expiration and close its spiracle, which is evidently an act of volition, the great con- strictor of the spiracle ought to be endowed with voluntary nerves. Un the other hand, since, as we know from experiment that the insect has a voluntary power of closing, it must also have a similar power of opening the orifice, and, consequently, the retractor valvule ought to be supplied from the same source as the constrictor. The remaining portion of the trunk of these nerves passes forwards and out- wards, crosses the retractor of the spiracle and gives off its third branch, which is again divided, and sends one portion backwards to the anterior (18) and the transverse abdominal muscles (17), and the other forwards to the transverse lateral (23). The remaining portion of the nerve is distributed to the dorsal muscles and teguments. The second nerve from the gangliated part of the cord is much smaller than the first. It passes diagonally backwards and outwards, and divides into two branches, the first of which is given to the latero-abdo- minal muscles, and the second to the triangular and transverse median, while the other (/c) passes downwards and outwards, and is con- tinuous with part of the third branch of the transverse nerves (i). Besides the nerves thus described as belong- ing to the moto-sensitive cord in the thorax and abdomen, there are others that merit particular consideration, both from the circumstance of their lying loosely above the cord, and from their special distribution. These nerves, which were formerly distinguished by us* as trans- verse nerves from the direction of their prin- cipal branches, and as respiratory from their special distribution to the respiratory organs, were discovered by Lyonet, and are delineated and particularly described in his anatomy of Cossus ligniperda. There is a plexus of them in every segment of the thorax and abdomen. Like the alary nerves of the cord in the thorax, there is a little difference in the distribution of some of them in the Sphinx from that of the corresponding plexus in the Cossus. In our earlier examinations of these nervesf we be- lieved them to originate from the posterior part of each ganglion of the cord, and this also was the opinion of Lyonet with reference to those in the Cossus which constitute the second and third plexus of the thorax, and the last of the abdomen, and which, he expressly states, do not come from the cords, but from the ganglia. J We have since been satisfied that the plexus in one segment is connected with that in each succeeding one by means of a minute filament, derived from the transverse portion of these * Phil. Trans. 1832, part ii. p. 389, and 1834, part ii. p. 401, also 1836, part ii. p. 544. t Op. cit. 1832. I Traite Anat. de la Chenille, 17G0, also 1762, p. 98 and 204. nerves, and which, passing laterally over and very close to the ganglion of the cord, joins its fellow of the opposite side, in the middle line behind it, to form the longitudinal portion of the next plexus, such filament gathering a few additional ones from the upper or motor sur- face of the cords. Hence, as we have stated,* these nerves are of mixed character, and con- tain some voluntary motor fibrils. Each plexus is formed of these two filaments, which, closely approximated together, pass backwards along the median line above the cord, until they arrive just before the next ganglion, where they diverge nearly at right angles, and are closely approximated to another series of fibres that runs in a commissural manner transversely across the body, from one side to the other. On each side a filament (e) is given off from the transverse nerves to unite with the moto- sensitive (f) close to the inner side of the smaller rectus. Near the external margin of that muscle it gives off another branch (g), which passes forwards upon the mus- cle, unto which it gives filaments, and then turns suddenly outwards (/i), to join a branch from the great moto-sensitive nerve, while a smaller branch is continued onwards to supply the remainder of the muscle. This union is exceedingly interesting, and illustrates the fact that, even in the Invertebrata, some of the nerves in one part are connected by loops with those in others, as noticed by physiologists in the Vertebrated classes. The next branch (i) of the transverse nerves is equally interesting from the same circumstance. It is continuous in the same manner with another branch of the moto-sensitive {k). This branch is composed of fibres that are approximated to the transverse trunk, and pass some from without inwards, and others from within outwards, to form the nerve («), leaving between them at its base a little triangular interspace, covered by a mem- brane and resembling the plexus (b). This nerve passes directly forwards until it arrives at the insertion of the greater recti (j), where it gives off a large branch to those muscles, and then passing beneath the oblique muscles, unto which it is distributed, and to the trian- gularis, becomes connected by loops with the second pair of moto-sensitive nerves (k) in the preceding segments. Neither of these two branches have been delineated by Lyonet in the Cossus. The next branch (/) of the trans- verse nerves is given to the trachea; and visceral surface of the great rectus, after which the trunk of the nerve passes outwards until it arrives at the tuft of tracheal vessels which are situated just behind the spiracle (F). It there divides (?«) into two branches, one of which passes on each side of these trachea;. Some filaments from the anterior branch pass inwards along the trachea towards the alimentary canal, while others are distributed to the transverse lateral muscles, dorsal recti, and lateral mus- cles of the dorsal vessel. The other division of the nerve also gives branches to the trachea; * Phil. Trans, part ii. 1836. 3 Q 2 948 INSECTA. and to the moto-sensitive nerve (ri), and, like the other, the obliqui and recti muscles and dorsal vessel. This division of the transverse nerve into two branches before it arrives at the trachea is not figured by Lyonet in the Cossus. In his delineation the transverse nerve crosses the trachea singly, posteriorly to the spiracle, where it communicates, as in the Sphinx, with the first moto-sensitive nerve from the gan- gliated cord, but does not give off a large branch anteriorly to the spiracle. We are thus particular in our description of these nerves, because it has sometimes been supposed that their distribution is precisely the same in all Lepidoptera, but which it is thus seen is not the case. Such, then, are the origins and the distri- bution of the nerves in the larvae of Lepidop- it);,into the description of which we have uitcit dthus minutely in order to show that seme nerves are distributed, more especially than others, to parts concerned both in the organic functions and the voluntary motions of the animal, and that others are given almost exclusively to parts that minister entirely to sensation and volition. Of the first kind are those which we have designated respiratory nerves; of the second are those we have described as the moto-sensitive, the proper nerves of the cord. The distribution of the first so especially to the respiratory organs is a circumstance which justifies us, we think, in still regarding them by that designation, whether they be considered as constituting a distinct system, as formerly supposed, or as being of a mixed character, connecting the organic with the voluntary func- tions of the body, as suggested by Professor Miiller, and as we now regard them. In our earliest inquiries into the structure and uses of parts of the nervous system in insects, we first described these nerves with reference to func- tion, as respiratory nerves, but it was after- wards suggested by Professor Grant that these ' might be motor nerves,' an opinion founded analogically upon the existence of a loose and easily detachable structure situated upon the nervous cord in the Scorpion and the Centi- pede, and which was imagined to be the motor tract, but which has since been shown to belong to the vascular instead of the nervous system. The structure which we regard as the true motor column, we have always found in close apposition with the sensitive, and in no instance lying freely upon or loosely attached to it. That the transverse nerves are indeed of a mixed character may readily be inferred from the description we have above given of their peculiar structure, which was in part noticed by Lyonet,* who called these nerves brides epiniires. It is distinctly seen that three sets of fibres enter into the composition of them. The commissural set, which runs transversely across the cord to each side of the body, is per- fectly distinct from the longitudinal that form the single loosely attached longitudinal portion of each plexus above the cord. The pecu- * Op. cit. p. 201. liarity of their distribution is also as remarkable as their structure. We have seen that they are given to the muscles of the wings, not sepa- rately, but approximated to other nervous trunks, which are derived both from the com- pound cord and from the ganglia ; that they are given to the muscle that connects the alimentary canal to the general muscular structures of the body ; that they are connected with the nerve from ganglia of the cord in each segment, are also given separately to the organic struc- tures, the tracheaa and dorsal vessel ; and that these nerves alone follow the course of the tracheae inwards to their distribution on the alimentary canal ; from all which it may be in- ferred that their function is certainly in part organic ; while the fact of their being also in part continuous with some of the nerves from the cord which are distributed to voluntary muscles renders it equally apparent that they are in part also connected with the function of volition. The nervous system of the perfect insect differs considerably in the size and relative position of its parts from that of the larva. Instead of its being almost equally distributed to every segment of the body, the greater pro- portion of it is removed forwards and concen- trated in the head and thorax. This concentra- tion takes place in every insect that undergoes a complete metamorphosis. The great principle upon which the development of the nervous system depends, is the approximation and concentration of the ganglion of the different segments, the shortening of the cords, and the formation of new trunks, by the enlargement, the changing of place, and the aggregation of several nerves into one bundle, occasioned and rendered necessary by other changes that take place in the body at a certain period. A concentration, therefore, of the nervous matter is regarded, both in the perfect and larva con- dition, as a proof of a higher stage of develop- ment in an insect than when the nervous matter is more equally distributed. On this account partly it is that the Coleoptera are considered the higher forms of insects, because, in addition to a more perfectly developed form of the tegu- mentary skeleton, there is also in them a concen- tration of the nervous masses, which, in the more perfect species of the order, are confined en- tirely to the region of the head and thorax. This is the case even in the larva condition of some of the Lamellicornes, Scarabaida, Geotrupidte, and Melolonthida, in which the nervous masses are confined to the first five segments, and the nerves radiate from them into the abdomen, as formerly shown by Swammerdam in Oryctes nasicornis. But although an aggregation of the nervous masses into one region of the body is usually, it is not invariably, a proof or an accompaniment of high development; since a condition similar to that of the larvae of the Melolonthida exists even in some of the lowest forms of larvae of other orders, as in the larvae or common maggots of Diptera, and in some of the perfect insects, as in the Gad-fly, (Estrus equi; while, on the contrary, a lengthened INSECTA. 949 form of cord and distribution of ganglia exists even in many of the more perfect Coleoptera, as in the Carabida (fig. 407) and Hydroplii- Fig. 407. Nervous si/stem of Carabus monilis. lidx. Swammerdam long ago showed this aggregation of nervous matter in the maggot of the cheese-hopper, and Burmeister has since observed even a more concentrated form in the larva of Eristalis tenax, the rat-tailed maggot of cesspools and privies. In the latter instance, as seen also by ourselves, the nervous system consists of a short nodulated cord, which does not extend beyond the three very short thoracic segments, and the greater portion of the body, the nine posterior segments, receives its nerves directly from the cord in the thorax, and not from a ganglion in each segment. This is a circumstance the more remarkable, if, as be- lieved by Straus and others, the existence of the ganglia is regulated entirely by the mobility of the segments or the existence of appendages, because, in these instances, the extremities of those segments in which the cord is placed are undeveloped, or only, as in Eristalis, in the most rudimentary form and almost useless, the sole organs of locomotion being the abdo- minal or false legs, while in the common maggots (fig. 358) both the abdominal and thoracic legs are absent, and locomotion is performed equally by every segment of the body. In addition to this it may be stated that in some of the active larvae of the most perfect Coleoptera, as in the Carabida, there is a lengthened form of cord and a ganglion in almost every segment of the body. Burmeister found the brain and twelve sub-cesophageal ganglia in the larva of Calosoma, and yet the insect possesses only six thoracic legs, the abdominal ones being entirely absent, excepting only the caudal leg or extremity of the abdo- men, in which segment there is no ganglion. These facts will prove that although a concen- trated form of the nervous system usually exists with a more perfect development of other parts of the body, it exists also when the develop- ment of other parts is imperfect. It is not, then, the immobility of the segments that regu- lates the disappearance of the ganglia, since, as Burmeister has justly remarked, there is as little motion of the segments of the abdomen in the perfect Carabida and hucanida, in which cords and ganglia exist, as in the Melolontludce, in which they are absent. Neither is it neces- sary that ganglia should be present as a means of supplying energy in segments upon which, as m Eristalis, the entire locomotive power of the insect depends, or that when ganglia are present they are necessarily connected with the function of motion. The most concentrated form of the nervous system in all its states exists in the Lamelli- cornes, the Scarabceidte, and MelolonthidiE ; but it is remarkable that even in these the development of the brain or supra-cesophageal ganglia is less perfect in the larva state than any of the other ganglia, and is not more advanced than in the Lepidoptera, in which, in the caterpillars of the nettle butterfly, Vanessa urticte, so late as the middle of the last period of the larva state we have found these ganglia very distinct from each other, being only approximated in the middle line by their convex surfaces. Towards the latter period of the larva state they become rapidly more and more united, and at the time of change have formed one continued mass, placed transversely across the oesophagus. A similar condition of the brain exists in the soft-bodied larva; of the 950 INSECTA. ' Lamcllicornes, as shown in Swammerdam's drawing of Oryctes,* and Burmeister has delineated a like condition in the larva of Calandra Sommeri.f We have before seen (fig- 405) that such is also the case in the brain of Timarcha. From this it would appear that the cerebral ganglia are the parts of the nervous system last perfected in the larva, while it is interesting to observe that the reverse is the case as respects the terminal ganglion ; that part, as correctly remarked by Professor Grant,J being the first to advance forwards and become united to the penultimate ganglion, to form the great caudal mass, at an early period of the larva. This is evident in the Timarcha, in which the eleventh and twelfth ganglia have coalesced into a single mass, while the cerebral ganglia only just meet above the oesophagus. But this is not the case in the perfect insect, (fig. 408,) in which the cerebral ganglia (A) Fig. 408. Nervous system of perfect state of Timarcha tene- bricosa. A, cerebral mass or brain ; B, optic nerves ; G, origin of sympathetic. have become greatly enlarged, united together, and represent a distinct brain, from which pro- ceed the uerves of sense, and united by long crura to the medulla oblongata (1), from which, are given off as before the nerves of the organs * Biblia Nat. tab. xviii. fig. 1. + Zur Naturgeschichte dor Gattung Calandra, fig. 13, Berlin, 1837. t Phil. Trans. 1832, part ii. p. 384. Outlines of Comparative Anatomy, p. 193. of manducation. The cords are enlarged, as also are the three ganglia of the thorax and their nerves, and a coalescence has taken place between the fourth, fifth, and sixth ganglia, their intervening cords being entirely obliterated, and the nerves aggregated together are now derived from one mass, the great meta-thoracic ganglion, the last part of the nervous system in the thorax. A similar change has also taken place in the remaining part of the cord and ganglia, which now forms the abdominal por- tion. The cord between each of the ganglia has been shortened, and the tenth, eleventh, and twelfth are united and form the caudal mass, which is situated about half way across the abdomen. Such are the changes that take place in the nervous system of an inferior type of Coleoptera ; in the higher forms, as in the Melolonthida, the series of approximated ganglia does not extend beyond the middle of the meta-thorax, the cords being terminated by a kind of cauda equina, all the nerves that go to the abdomen are aggregated together and' extended into that region over the post-furca. A similar structure, but in a less complete form, exists in the JJi/tiscida, in which, as in the Hi/daticus cinercus, a short cord is found with seven constrictions upon it, corresponding to that number of ganglia which probably existed in the larva state, but have nearly dis- appeared during the metamorphoses. But that this concentrated form of the nervous system is not necessarily connected with high develop- ment of other parts of the body is further shown in the common Earwig, Furficula auri- cularia, in which there are ten distinct sub- Fig. 409. Nervous system of the Earwig ( Forficula auricularia ). oesophageal ganglia. The first, or medulla, is large and closely connected by very short crura with the brain, there being only a narrow INSECTA. 951 passage between the two for the oesophagus. Each segment of the thorax contains a ganglion, the meta-thoracic one, which gives nerves to the wings, being the largest. In the abdominal portion of the cord, which extends as far as the penultimate segment, there are six double ganglia very distinct fr,om each other. This is exactly the number found by us in the same portion of cord in the Car-abida:, although, according to Burmeister, there are only five. Thus, then, in the Forficulida, in which there is the most extensive motion of the segments of the abdomen, there is the same number of ganglia as in the Carabida, in which most of the abdominal segments are anchylosed together and immovable, as in the Lamelli- cornes, in which the whole of the cord is situated within the region of the thorax. In the oil-beetles, as in Proscarabuvus vulgaris, there are as usual three thoracic ganglia, the largest being the meta-thoracic, although the proper wings, and scarcely even the elytra, do not exist. In the abdominal region there are five ganglia, but smaller than those of the thorax, although it is stated by Burmeister* that these ganglia of the thorax are larger than those of the abdomen when perfect organs of flight are developed, but smaller when they are absent. So far as our own observations have extended, we have invariably found the thoracic ganglia larger than the abdominal, whether organs of flight exist or not, a condition that might naturally be expected whether the ganglia be connected with the production of nervous energy in the parts, or be only the centres of sensation. In the full-grown larva of this insect, of which we have examined a considerable number, but which at present appears to be scarcely if at all known to naturalists, we have found twelve per- fectly distinct sub-cesophageal ganglia. Of these the fifth was the largest and separated from the fourth only by a very short cord, as were also the eleventh and twelfth, besides which the twelfth was larger than the eleventh, and ap- peared as if formed at an early period of two approximated ganglia. That in the earliest state of this insect there are thirteen sub- cesophageal ganglia seems highly probable. On watching the changes that tal,) which is believed to be continuous with the delicate pigment that is interposed between the cornea?. It covers the whole of the inner surface of the cornea, excepting only in the centre, where it is perforated by a minute hole or pupil- lary aperture, (e,) to admit the rays of light that have passed through the cornea. Between this pigment, which is the curtain or iris of the eye, and the end of the cornea, Duges found a space, («,) filled with an aqueous humour. Be- hind the iris of each cornea is a little cone- shaped transparent body, (_/',) with its apex directed backwards in the axis of the eye. It is filled with a perfectly transparent tenaceous fluid, the vitreous humour of the eye,into which the rays of light received through the cornea and iris are admitted, to fall upon the retina, or termination of the nerve, (g,) at the apex of the cone. The length of the cone differs greatly in different insects. It is shortest in the Dip- tera, and scarcely exceeds its breadth. In the Coleoptera and Lepidoptera it is five or six times longer than it is broad, and perhaps even exceeds this in some of the Libellulina. The apex of each cone is received upon the extremity of one of the many thousand of fibres (g) which we described as radiating from the bulb of the nerve, immediately after it has passed through the optic foramen. The choroid of dark pigment that forms the iris (A) is conti- nued backwards over the surface of the cone and optic fibre to the bulb of the optic nerve, thus completely insulating every individual cone and fibre from those by which they are surrounded. It is in the spaces thus occupied by the choroid that the tracheal vessels and cir- culatory passages ramify, so that the choroid in the eyes of insects, as in those of the verte- brata, is the proper vascular structure of the organ. It is subject to much variety of colour in different insects, being in some nearly black, in others dark blue, violet, green, purple, brown, or yellow. In some there are two or three layers of pigment of different colours. The usual arrangement of these is first a dark coloured portion near the bulb of the optic nerve, then a lighter colour, and lastly, again, a darker near the cornea?. According to Duges, the base of the cone is rounded where it is co- vered by the iris, but Muller states that this is the case only when the cornea is devoid of facets or corneules, and is perfectly smooth. According to the same authority, the pupillary aperture is most distinct when the cones are short, as in Diptera. This aperture was disco- vered by Muller, and also the nature of the cones, which had been thought by Straus- Durckheim to be expanded terminations of the optic fibres. We have seen the iris and pu- pillary aperture very distinctly in the eye of Pontia brassicce, the white cabbage butterfly, and also in Sphinx ligustri and Nepa grandis. In the two latter instances it is of a dark brown, or nearly black, and is particularly large in Nepa. In Pontia it is yellow, in the centre of which the pupil exhibits a glassy brightness. The manner in which the extremity of the ner- vous fibre is connected with the apex of the cone has recently been investigated by Professor INSECT A. 961 Wagner, who has found that the fibre is pro- longed as a sheath over the sides of the cone, of which it is supposed to form a part. In this manner, each of the thousands of corneules or facets that form die compound eye, transmits impressions from without inwards to the optic nerve and brain, the perception of each being- confined to that of the object immediately before it, or in a line with its axis of vision. On the exterior surface, between each cornea, there are often some very fine hairs, as on the cornea of the bee, which Burmeister likens to eyelashes, and thinks that they assist to con- fine the field of vision, as well as protect the cornea. This is the usual structure of the eye. In Melolontha, Straus-Durckheim describes the filament of the optic nerve as passing through a second or common choroid, and as afterwards uniting to form a general retina, which is connected with the optic nerve by means of short thick columns. The use he assigns to this structure is that of intercepting tlie impressions of light, which might otherwise be too powerful. The ocelli, or simple eyes of insects, re- semble those of Arachnidans,* in being formed of a very convex, smooth, single cornea, benea as ln most larva?, is soma sycophanta. muscular and folded ( Burmeister. ) ■> . . , transversely, and altogether the canal is more developed than in the pre- ceding instances, as also are its appendages the hepatic vessels, which are exceedingly long, although no cceca are developed upon them. In the lihinchophora and Longicornes there is a still higher form of alimentary canal, as observed by Burmeisterf in Culundra * Transactions of Entomol. Society of London, vol. i. part 3. t Zur Naturgescliichte dcr Gattung Calandra. Beilin, 1837. 7 INSECTA. 969 Sommeri, and as seen by ourselves in Callidiwn luridum. In Calandra, which in external ap- pearance is scarcely more perfect than the apodal larva of Hymenoptera, the alimentary canal (jig. 427) approaches much in form, Fig. 427. size, and complication of its parts to that of the perfect insect. It commences behind the pharynx in a very short pear-shaped oesopha- gus (II), which opens by a valve into a dilated bag-shaped crop (I), analogous probably to the first stomach of the larva of Ccuospma. This is continuous by a narrowed passage with the proper digestive cavity, around the middle part of which (K) are developed many conical glan- dular papillae or gastric vessels, that do not appear to have been noticed in the larva of Culusoma, which instead of subsisting upon hard vegetable substances like these Curculio- nidic, preys upon the soft bodies of living cater- pillars, and consequently does not require for the digestion of its soft animal food and juices so complicated a structure as those which de- vour large quantities of crude vegetable matter, as is the habit of the Lamellicornes, or the hard and less easily solvent woody fibre or coverings of insects devoured by the Calandra or the perfect Carabida;. At the posterior extremity of the digestive stomach in this larva are in- serted, as before seen, the biliary vessels, not singly around the sides of the canal, but by the union of four of these tubes in a common duct. This peculiarity is remarkable, as it occurs in some species in the perfect in- sect. Besides these vessels there are two others somewhat smaller, which are inserted separately, a little anterior to the common duct. These have been supposed to be analogous to pancreatic vessels, but they are similar in almost every respect to those which are inserted by a common duct, and hence may be supposed to have nearly the same functions. We have noticed similar vessels inserted sepa- rately from the supposed hepatic vessels in the Dijticidte and in Timarc/ia, which certainly leads to the conclusion that they have some difference of function. The ilium (L) is of great length, and more convoluted than we have yet seen it in any larva, and ends in a very muscular cylindrical colon (M N), terminated by a short rectum. A similar and perhaps even more highly developed form of alimentary canal exists in Callidum luridum, in which the anterior portion of the oesophagus commences with a small neck, and is then enormously di- lated, after which it becomes gradually narrowed and constricted, and is joined to a second sto- mach, which in like manner is also dilated at its anterior extremity. In the middle part of its course it is twice folded, and is covered with minute coeca, as in Calandra, like which it ter- minates in a valvular pylorus, and receives at the same time the insertions of the hepatic ves- sels. The ilium is also of considerable length, is exceedingly muscular, and is dilated in two parts of its course before k terminates in a straight and very muscular colon and short rectum, as in Calandra. The length and com- plication of the intestines, therefore, appear to have some reference to the quality of the food to be digested, since it is well known that the food of these latter insects is of difficult assi- milation, being as it is chiefly the hard ligneous fibres of vegetable matter; but they cannot be received as always indicatory of a carnivorous vegetable feeder, since, as above remarked, the length of the canal is considerable in one en- tirely carnivorous larva, while it is much shorter in some herbivorous, and particularly in polleni- vorous larva?, as in the Melulont/ia and the apodal Hymenoptera. In the perfect insect, the length of the ali- mentary canal is not more indicatory of the ha- bits of the species than in the larva. It is nearly as long, and is more complicated, in the rapacious Carabida: (Jig. 423) than in the honey-sipping Lepidoptera, whose food is en- tirely liquid, while, as we have seen, it is only a very short tube in the pollenivorous larva, which subsists upon a mixture of pollen and honey ; but in the perfect insect, which subsists upon honey alone, and which it might be sup- posed requires little power of digestion, the canal is long and tortuous. In the rapacious Carabida, it is from two to three times the length of the whole body. At its commence- ment at the pharynx it is funnel-shaped, and opens directly into the oesophagus (fig. 424,//), which is gradually enlarged as it passes through the thorax, until it arrives at the meta-thoracic segment, where it becomes greatly dilated, and 970 INSECTA. forms a large bag or crop, which we shall pre- sently see more perfectly developed in the Ilaustellata. While passing into the abdomen, this part becomes suddenly constricted, and terminates in a short neck, immediately behind which is an oval and very muscular gizzard (£), which is developed internally into four broad longitudinal horny ridges (a, b), armed with strong sharp bristles, as formerly shewn by Leon Dufour* in insects of this family. Be- tween these ridges are two channels armed in like manner with a double row of minute hairs, which assist in more minutely comminu- ting the hard parts that are passed into the gizzard and escape trituration by the ridges. The substance of the gizzard is particularly muscular, and resembles in colour the gizzard of a bird. On its external surface the thin shining pentonceal coat is very distinctly seen. At its base the gizzard is much constricted, and the ridges within it meet together so as to form a distinct valve, by which this is divided from the next portion of the alimentary canal, the chylific ventricule (k). This part is capacious and muscular, and the double mucous lining within it is very distinct. It is of considerable length, and is gradually decreased in size from its com- mencement to its termination at the pyloric valve, where, as in the larva, it receives the he- patic vessels. It is covered throughout its whole course by an immense number of appa- rently ccecal vessels («, b, c), which in the upper half of its course are of considerable length, but in the lower become gradually more and more shortened. Burmeisterf thinks these ccecal vessels are derived entirely from the inner or mucous coat of the ventricule by intussus- cepted portions, which pass through the mus- cular coat between the fibres which are pushed aside by them, and consequently that they do not derive any covering from the muscular coat, but of this we have considerable doubt. In- ternally they certainly open each by a distinct valvular oritice, derived from the mucous lining, as we have seen in Carabus monilis (b), and externally are covered by the peritonceal coat, and on each side are furnished with a minute ramifying tracheal vessel, derived from the tra- cheae which are distributed over the alimentary canal, as shewn by Dufour. We cannot, how- ever, imagine that they derive no covering from the muscular coat of the ventricule, more espe- cially while it is admitted that the ccecal appen- dages attached to the anterior and posterior por- tion of the ventricule in the Gryllida derive a portion of their structure from the muscular coat as well as the mucous. These are most decidedly secretory organs, and elaborate a fluid, probably distinct in its chemical composi- tion from that of the biliary vessels at the pyloric extremity of the stomach. The ilium (/) is of considerable length. On its exterior surface the longitudinal muscular bands are distinctly marked. It is much longer in pro- portion to the other parts of the intestine in the perfect insect than in the larva. It terminates in a very large pear-shaped colon (;«, n), the * Annales des Sciences Naturelles, torn. ii. pi. 20. t Op. cit. p. 132. upper part of which corresponds to the ceecum, which we shall see highly developed in some other species. It is there marked by six elon- gated elevated glandular protuberances, situated between the longitudinal muscular bands. These elevations seen on the exterior of the part correspond to others which we have found equally strongly marked in the colon of Hy- menoptera, and we suspect are the mucous glands of the great intestine. The colon is usually distended with faeces, and terminates in a very short narrow rectum (o). At each side of the colon are situated the anal or urinary vessels (s), which we shall presently describe. This may serve to illustrate the general form of the alimentary canal in carnivorous Coleoptera. In certain parts of its course it is, however, more developed in other species. Thus in the Dytkida, we have found the oesophagus in Hydulicus cinereus, as described by authors in Dyticux, expanded into a large crop-shaped bag, and the stomach shorter than that of the Carabidce, and covered by long cceca throughout its whole extent. It receives at its base the in- sertion of four large hepatic vessels, and also two very much smaller ones, similar to those just seen in the larva of the Culandrli. The anal vessels are also present, but their excretory bladder is larger, and its neck much shorter than in the Carabidm. The most remarkable structure is in the proventriculus or gizzard. The external appearances of this part resembles that of an acorn in its cup. It is exceedingly muscular, and is armed internally with four re- markable teeth arranged around its inferior por- tion, between four horny ridges developed from the mucous lining of the part, and covered with very strong stiff hairs, as in the Carabidtc. Each of these teeth is broad and somewhat oval at its base, and in shape resembles a helmet, the crest of which is acute, and armed with two sharp- pointed prominences adapted for cutting the food, which it is known is swallowed more rapa- ciously and less comminuted by these insects than by Carabida. This form of alimentary canal with a gizzard and gastric cceca exists in the Silphidte,* and most of the carnivorous feeders. Thus it exists also in Staphylinidte,\ in which we have found the gizzard in Creophi- lus maxillosus armed with double longitudinal horny ridges, covered with stiff hairs as in Ca- rabus, like which also the stomach is covered with gastric cceca, which are larger at the an- terior than at the posterior part of the organ. The anal vessels are also largely developed. Dufour has observed the same in Stap/iyli- nus erythropterus. The gizzard is also found in some of the Neuroptera. It is very largely developed in the carnivorous Pumtrpa com- munis, in which, however, we have not found it thrown into regular longitudinal folds, but into transverse and oblique rugae covered with stiff hairs. The alimentary canal in this species is of considerable length, perhaps nearly three times that of the body. The oesophagus is short? but is developed at its under surface into a minute oval crop, perfectly distinct from * Dufour, op. cit. torn. iii. pi. 13, fig. 5. t Id. INSECTA. 971 the common cavity of the oesophagus, although not separated from it by a valve, neither is the oesophagus separated by a valvular structure from the gizzard. The chylific stomach is ex- ceedingly long and cylindrical, but is without gastric coeca, like the larva of Car-abidee, since like that, the Punorpa appears to subsist rather by sucking the juices than by swallowing the hard parts of the body of its victims. Thus, then, although in the Cicindelida '(fig. 37, vol. 1), the canal is scarcely longer than the body, as formerly shewn by Dufour, and since fre- quently instanced as proving that the length or shortness of the canal is characteristic of a car- nivorous or phytophagous feeder, we cannot admit that the length of the digestive organs, and the existence of a gizzard and gastric ves- sels, are indicatory of predacity of habits in the insect, because a similar conformation of parts exists often in strictly vegetable feeders. The existence and length of these parts seem rather to refer to the comparative digestibility of the food than to its animal or vegetable nature. Among the more omnivorous feeders, as in the Forficulida, the gizzard is still present. In Forjicula auriculuria the oesophagus is long and dilated, and a short, broad, and very muscular gizzard is present. Internally it is thrown into six longitudinal folds, which pro- ject for some distance at their extremity into the cavity of the digestive stomach, to the en- trance of which, when closed, they serve as a valve. The canal of this insect, which, although in part carnivorous in its habits, certainly is not of the most rapacious nature, but lives equally upon the juices of fruits and flowers, is scarcely longer than that of the most predaceous Cieindela or Dyticus, since it passes almost in a direct line through the body, making but one slight convolution, a further proof that the length of the canal must not be taken as a cri- terion whereby to judge of the habits of a species. This will apply equally to the om- nivorous Gryllidee, in which there exists a short alimentary canal, but a gizzard of more com- plicated structure than that of Di/ticida. In these insects the two layers of the mucous coat are visible even in the oesophagus. The second layer is distinctly glandular and secre- tory, and in it there are many thousands of very minute granulary glandular bodies, which probably secrete the fluid that is often ejected from the mouth of the insect when captured. The inner layer, or proper mucous lining, is often folded longitudinally, and in Acrida viridissima these folds, which are six in number, assist to form a valve between the oesophagus and gizzard. They are each armed with five very minute hooked teeth, and continued into the gizzard develope many more in their course through that organ. These first teeth are ar- ranged around the entrance to the gizzard, and seem designed to retain the insufficiently com- minuted food and pass it on to that organ. Next to these in succession on each of the lon- gitudinal ridges are four flat, broad, and some- what quadrate teeth, each of which is very finely denticulated along its free margin. These extend about half-way through the gizzard. They appear to be alternately elevated and de- pressed during the action of the gizzard, and to serve to carry on the food to the twelve cutting teeth with which each ridge is also armed, and which occupy the posterior part of the organ. These teeth are triangular, sharp-pointed, and directed posteriorly, and gradually decrease in size in succession from before backwards. Each tooth is very strong, sharp-pointed, and of the colour and consistence of tortoise-shell, and is armed on each side by a smaller pointed tooth. These form the six longitudinal ridges of the gizzard, between each two of which there are two other rows of very minute teeth of a tri- angular form, somewhat resembling the larger ones in structure occupying the channels be- tween the ridges. The muscular portion of the gizzard is equally interesting. It is not merely formed of transverse and longitudinal fibres, but sends from its inner surface into the cavity of each of the large teeth other minute but powerful muscles, a pair of which are inserted into each tooth. The number of teeth in the gizzard amounts to two hundred and seventy, which is the same number in these Gryllidee as found formerly by Dr. Kidd* in the mole- cricket. Of the different kinds of teeth there areas follows: seventy-two large treble teeth, twenty-four flat quadrate teeth ; thirty small single-hooked teeth, and twelve rows of small triangular teeth, each row being formed of twelve teeth. This is the complicated gizzard of the higher Orthoptera. In the same insect immediately posterior to the gizzard the chylific stomach is expanded on each side into two large rounded coeca, into the upper part of which some minute vessels are traced which in appear- ance resemble the hepatic vessels. Posteriorly to these ccsca the stomach becomes narrowed and makes one convolution, and receives around its termination the hepatic vessels, which are small but very numerous. It then is continued backwards as a long ilium, and terminates in a muscular banded colon without a distinct rectum. The whole length of this alimentary canal does not exceed more than about one length and a half of that of the body. A simi- lar structure exists in the Blattida. In these insects eight large vessels are inserted around the commencement of the stomach behind the gizzard. Four of these are long and four short, and as observed by Burmeister, these have been thought to be analogous to pancreatic or gastral salivary organs. In the proper Locustidte there is only a rudimentary gizzard, as Bur- meister has shown in Locusta migratoriu, in which the interior lining of the whole oeso- phagus and crop is covered by an immense number of very minute horny teeth, for the purpose of comminuting the hard ligneous matter which we have sometimes found in foreign specimens. The rudiments of the gizzard exist in six flat pieces, studded with minute teeth like the lining of the oesophagus. The commencement of the stomach is sur- rounded by two sets of coecal appendages, six in each set, and similar in form to those of the second set in the larva of Melolontha, like which those on the under surface are the J Phil. Trans. 1826. 972 INSECTA. Alimentary canal of Lucanus cervus. G, anterior muscles of the pharynx; H, oeso- phagus -, I, gizzard ; K, chylific stomacli ; L, ilium ; M, colon (ccecal portion of) ; N, colon ; O, rectum ; a, frontal ganglion on the vagus ; b, vagus ; c, an- terior lateral ganglion connected to the vagus. longest. These are evidently analogous to the vessels in Blatta. But one of the most remarkable forms of alimentary canal with reference to the habits of the insect exists in the male Lucanus cervus (Jig. 428), which subsists entirely upon fluid aliment, as proved by the observations of natu- ralists, and confirmed by the fact that its mouth is unfitted for mastication. In this insect the oesophagus (H) is usually long and narrow, and terminates in the meso-thorax in a well deve- loped gizzard (I), as in the Carabus, and this is succeeded by a long chylific stomach (K), covered throughout its whole extent by very minute rudimentary coeca, as first noticed by Dufour. It makes three distinct convolutions, and is then divided by a pylorus, which re- ceives four hepatic vessels (P) from an ex- ceedingly short ilium (L), which passes directly in an enormous colon. The upper portion of this(M) is divided from the lower (N), which is thus divided into colon and ccecum. It ter- minates in a long folded rectum (N, O), and the whole are usually filled with faeces. Now this insect, in which both gizzard and gastric vessels are present, can scarcely require these parts for the purpose of triturating its food, which is entirely fluid, besides which, being one of those species that undergo a complete metamorphosis, it can scarcely be supposed to be simply a remains of what existed in the larva state. The presence of the gizzard may be looked upon as somewhat anomalous. Again it may be remarked, that in Hymenoptera the stomach, which in many species digests only liquid concentrated food in the form of honey, is much longer than in those instances, as in Orthoptera, in which the food is less easily digestible. In the Apid) is long and narrow, and in the metathoracic seg- ment is dilated into a large crop (t) connected by a distinct neck, but not divided from it by a valve. This is usually filled with air, and has thence been called the sucking stomach, but in the Diptera, in which it also exists, and com- mencing much nearer the pharynx is extended backwards as a long and gradually enlarging tube until it reaches the anterior part of the abdomen, where it is expanded transversely into a large bag, we have certainly found it partially filled with food. This has often been found to be the case in the common flesh-fly. In EristalisJloreus(1) we have found it partially filled with yellow pollen from the flowers of the ragwort, upon which the insect was cap- tured. We have at the same time observed INSECTA. 973 Fig. 430. Fig: 431. Alimentary canal of Sphinx ligustri. the pollen in the canal leading to the bag, in the oesophagus, and in the stomach itself. A gizzard does not exist either in the Diptera or Lepidoptera, but there is a slight rudiment of it in the Sphinx (i). The stomach of Lepidop- tera is in general short, oval, or a little elon- gated (k), and always very muscular, and as in other insects, the hepatic vessels (p) enter at its pyloric extremity (q). The ilium (/) is of considerable length. In the Sphinx it makes seven folds, and then passes straight to the A Umentary canal of Pontia brassicee. colon, which is developed anteriorly into a very large coecum (///), and terminates in a narrow short rectum («). Throughout its whole course it is covered by the hepatic vessels. In the Pontia brassica (fig. 431), the digestive sto- mach is preceded by a very muscular and transversely banded portion of canal resembling the stomach of Hymenoptera. It is in the pre- cise situation of the gizzard in other orders, and appears to be the representative of that part in tli is insect. The true stomach is long and oval, and the ilium is longer than in the Sphinx, and the ccecum, colon, and rectum are all distinct. In the Diptera the alimentary canal is usually very long, and is scarcely at all shorter in the carnivorous than in the omnivorous feeders. Appendages of the canal. — The first of these, the salivary glands, are very frequent in most of the orders, but vary greatly in form and number. In Lepidoptera they are simple elongated tubes (A), which extend into the thorax and are convoluted beneath the oeso- phagus and anterior portion of the alimentary canal. In the larva they constitute the silk vessels, and empty themselves by a single duct through the spinneret on the floor of the mouth. They are formed of three por- tions ; first, the excretory, which is thin and transparent, and is gradually enlarged as it passes backwards along the body ; second, the apparently secretory portion of the organ, which is of an elongated cylindrical form, externally transversely marked as if formed of muscular fibres, and internally covered with a vast number of rounded glandular bodies, as we 974 INSECTA. have seen in the recently detached vessel of Vanessa urtica ; and lastly of a third portion, which consists of a minute vessel, extended from the apparently coecal extremity of the middle portion of the organ, as formerly shewn also by Lyonet in the Cossus. In the perfect insect these parts still exist, but very much reduced in size. In the Cossus Lyonet has shewn four of these vessels, two of which, the proper silk vessels, open by a single excretory duct, and the others separately into the cavity of the mouth. In some Coleoptera, as in the Blapsidce, these organs are formed of many ramifying tubes united on each side of the oesophagus into a single duct. In others, as in the Orthoptera and Hymenoptera, they con- sist of an immense number of rounded, opaque, glandular bodies, aggregated together in small clusters, which communicate by many small ducts, inserted at irregular distances, with a large and partially convoluted common or ex- cretory duct, that opens on each side of the mouth, so that each of these collections of glands resembles a bunch of grapes or currants. Each of these rounded granules, or acini if we may so call them, receive a minute vessel, but whether this is distributed over its surface or is received directly into its substance we have been unable to ascertain. These aggre- gations of salivary glands are usually situated on each side beneath the oesophagus in the pro- thorax, and are very distinct in the Orthoptera and Hymenoptera, in which they have been often noticed. Muller has seen them in Phasma, Treviranus in Apis, Burmeister in Locustida, Grt/llidte, and Termes, and we have also seen them in Loc ustidce and Gryllida among the Orthoptera, and in Bombus, Apis, Ant/io- phora, and Athalia among the Hymenoptera. Their existence in the latter genus is somewhat interesting from the circumstance that the large quantity of salivary fluid which these organs seem calculated to produce appears to be entirely employed in moistening the dry pollen of flowers upon which the perfect insect chiefly subsists, before it is passed into the oesophagus, and not in the habits or in constructing of a nest, as is the case with the bee, which always employs it as a solvent for the wax in the con- struction of its combs. In the latter insect, according to Burmeister, the evacuating duct of these organs is a minute spiral vessel re- sembling a trachea, and empties itself into the tube of the proboscis or ligula. The form and number of these salivary organs varies in the different classes; the usual number is two, but in Apis Cimex and Palex there are four, each pair of which unite into one duct, while in JVepa there are as many as six.* In the Tabanida there are only two short ccecal tubes, into which many minute vessels empty them- selves.! Those gastric vessels, which are in- serted at the commencement of the digestive stomach we have above stated have been re- garded as salivary organs, but there is consi- derable doubt respecting their real function. Burmeister considers them to be analogous to the pancreas, but if this be admitted to be the case in the Orthoptera, those vessels also which cover the exterior of the digestive stomach in the carnivorous Coleoptera must be of the same description, since both empty themselves into the digestive stomach. But we cannot coincide with him in this opinion, since from an experiment which we shall presently notice there is reason to believe that the fluid poured into that cavity during digestion is of an acid nature, analogous to that which is found under similar circumstances in the stomach of ver- tebrata ; while that of the proper salivary organs is believed to be alkaline, as was for- merly supposed by Rengger. Treviranus also believed the same of the saliva of the honey- bee, having witnessed its employment by this insect in the formation of its combs. We have also seen this insect reduce the perfectly trans- parent thin white scale of newly secreted wax to a pasty or soapy consistence, by kneading it between its mandibles, and mixing it with a fluid from its mouth, before applying it to assist in the formation of part of a new cell, so that we have good reason to believe that ihe salivary fluid thus employed asa solvent for the otherwise brittle wax is of an alkaline quality. The Malpighian or supposed biliary vessels (Jig- 432, p ) usually enter the canal, as we have seen, at the pylorus. They vary greatly in number from two to twenty or even a hun- dred, as in some of the Orthoptera and Hymen- optera, but in all insects their function appears to be similar. They are usually from four to six in number, and are very long tubes that pass from their insertion or opening into the canal behind the pylorus directly forwards about half way along the sides of the stomach, and are then reflected backwards as far as the ilium, around which and the colon they make many convolutions, and in the Lepidoptera terminate, or perhaps we ought rather to say originate, each in a minute vessel, which be- comes smaller and smaller in proportion to its length, and in which we can perceive no dis- position to form a coecal termination, although we have been unable to trace it to its origin, which is certainly in the vicinity of the posterior part of the colon. Of this we have satisfied ourselves by following these vessels in the larva of Odonestis potatoria, which the colour of their contents, an opaque bright yellow, has rendered practicable. We have traced them until the yellow colour has disappeared in an opaque white, and this has been also lost in a perfectly transparent fluid, after which we have been unable to follow the vessels further. In other insects they appear to end in coecal ex- tremities, but we certainly could not observe this in the larvae of Lepidoptera. It has also been supposed by some anatomists that these vessels form a double communication with the alimentary canal, but this has entirely escaped our observation. In the larva of Sphinx ligustri and most other Lepidoptera these vessels are covered by an immense number of minute oval coeciform dilatations (fig. 432, a ), as is also the case in some of the perfect Coleoptera, Mclolontha* as shown by Dufour, Straus Burmeister, op. cit. p. 146. t Id. 145. * See Animal Kingdom, vol. i. fig. 38, c. INSECTA. 975 Fig. 432. a, part of the hepatic vessel of the larva of Sphinx ligustri when nearly full grown, showing the cceca ; h, part of the same in the pupa, the coeca disappearing, Durckheim, and others. From each of these supposed coeca in the larva of sphinx we have traced an exceedingly minute and transparent vessel which has appeared to be connected with other delicate ramifications, and sometimes with the immense quantity of adipose sacculi with which the whole viscera are surrounded. These Malpighian vessels undergo considerable, changes while the insect is passing from the larva to the perfect state. The cceca begin to disappear soon after the insect has entered the pupa state (b), and not a trace of them is dis- coverable in the perfect insect, so that the function of the organ is gradually diminished in activity. During the larva state they exhibit a remarkable peculiarity at their connexion with the alimentary canal which seems to have some reference to their function. It is a dilatation at the point of union of these vessels in the sphinx to form a single duct that opens into the ilium, and if these be hepatic vessels may represent a gall-bladder, as once observed to us by Dr. Grant, but the exact function of the vessels is very difficult to determine. The following observation which we made in the summer of 1832 and havesince repeated seems a little to show the nature of the contents of these vessels, and also of other parts of the alimentary canal. We gave sugared water, coloured with indigo, to some specimens of Vanessa urlica which had been confined for several hours without food after they had left the pupa state. On examining the insects about two hours afterwards the stomach was found filled with fluid containing a great quan- tity of pink-coloured granules, which appeared to be the vegetable indigo acted upon by the acid contents of the stomach by which it had become saturated, thus distinctly indicating the presence of an acid in the stomach during digestion. But it was remarkable that some of the indigo that had passed the pyloric extremity of the stomach, where these supposed biliary vessels enter, and had also passed throughout the whole length of the ilium and even in part into the colon, had been restored again to its original dark blue colour, thus indicating the presence of an alkalescent fluid secreted either by the hepatic vessels or the ilium along which the indigo had passed. But another curious circumstance was that the hepatic ves- sels also partook of the same pinkish hue as the contents of the stomach, which seemed to indicate that the contents of these also are acid. The conclusions we drew from these observa- tions, which we repeated very carefully in 1834, were, that there is an acid gastric juice secreted in the stomach during digestion, that the contents of the so-called hepatic vessels are probably also acid, and that an alkaline fluid is secreted by the ilium, otherwise the indigo reddened in the stomach could not have been restored to its original colour. These circum- stances seem to lead to the conclusion that the Malpighian vessels are rather uriniferous than biliary, more especially as they have been found by Chevreul* and Audouinf to contain uric acid; but if this be really their function, a question then arises why they are inserted so near to the pyloric extremity of the stomach in almost all insects, and the excreted fluid be thus required to traverse nearly one-half of the whole alimentary canal before it is ejected from the body ? This consideration still inclines us to suspend our opinion as to their true function, and leads us still to believe that they may be in some way connected with the function of digestion and assimilation. The anal or proper uriniferous organs. — We agree with Burmeister that the anal are the true urinary organs. They do not in general evacuate their contents directly into the canal, but on each side of the anus. They exist, as we have seen, in the Curabidte (Jig. 424, s ), and their general form, as long ago shown by Dufour in these insects, is that of a long vessel convoluted upon the colon and emptying itself into an oval or kidney-shaped vesicle on each side of the colon, and terminating in a single duct close to the anus. Dufour found the minute vessel on the colon connected with an aggregation of rounded glandular bodies, each connected with the vessels by a very minute filament, but we have overlooked this structure in our own examinations. Neither have we seen it in the Di/ticida, in which each urini- ferous organ commences in two apparently coecal tubes, which, after being a little convo- luted, unite into one which empties itself into a vesicle on each side of the colon and rectum. Similar vesicles have been shown by Dufour in the Staphylinida, as in Staphylinus erythropterus and in the Sdphida, in both which we have ourselves distinctly seen them arising by a single vessel which empties itself into an urinary bladder on each side of the anus. In the Silphida this bladder opens directly into the termination of the rectum. The adipose tissue. — This tissue, which it is necessary to allude to in connexion with the organs of nutrition, consists of an immense number of little transparent membranous vesicles filled with opaque adipose matter, which, in the generality of insects, is perfectly white, but in others, as in the butterflies, is of a bright yellow colour. The vesicles are usually very irregular in form, being sometimes nearly oval and at others elongated or triangular. They communicate freely with each other and form a most intricate web or reticulated structure. They cover the whole of the abdominal viscera * Straus Durckheim, Considcrat. tkc. 1828, iv. 251, t L'institut. 135. 976 INSECTA. like the omentum of the higher animals, and they are extended also among the muscles; between which they occupy the interstices, both between the different layers and the tegumen- tary skeleton. They do not form in the abdo- men one continuous surface like the mesentery, but are simply attached to each other, and to the surrounding structures by constricted por- tions, which allow of the freest communication. They are most abundant in the abdomen, but are extended into the thorax and cover more particularly the nervous cord. There are but very few in the region of the head or in the extremities. We have never yet seen them in actual communication with bloodvessels, although we have observed them attached by minute points along the whole course of the dorsal vessel, in the abdomen, as if they were in some way connected with the return of the blood to the auricular space that appears to surround that organ. It is amongst these vesicles in particular that the Malpighian or so-called biliary vessels extend around the alimentary canal, and the tracheae ramify among them in the greatest abundance, but we have not observed them distributed over the sides of individual vesicles as over some other structures. These circumstances lead us to suspect that the vesicular structures are in some way con- nected with the circulatory system, although they cannot be regarded either as arteries or veins. May they not serve the purpose of lymphatics, while they become at the same time depositaries of the nutrient matter? Oken and Treviranus appear to have considered them as analogous to the liver, and the latter author has supported his opinion by the existence of a somewhat analogous structure in the scorpion, which is believed to be the liver of that animal. That they are most intimately connected with the function of nutrition is proved by the cir- cumstance that they exist in the greatest abundance at the period when the larva ceases to feed, just before it enters the pupa state; that their contents are gradually diminished during that condition ; and that they disappear most rapidly towards the latter end of the pupa state, when the organs of generation are in the most rapid progress of development. After the insect has entered the perfect state their contents have nearly disappeared. Added to these circumstances we have observed that, during the earliest periods of the larva state, the quantity of adipose substance contained in the vesicles is very small, and also that in all perfect insects that pass the winter in a state of hybernation the quantity of adipose matter is much greater than in those which do not live through the summer, while it has nearly all disappeared in these insects after they have left their hybernacula in the spring. We have remarked these circumstances particularly in the later broods of butterflies, which being hatched at the end of autumn pass the winter as hybernants and appear again in the spring, and we have constantly noticed the same thing in the large females of Bombus terrestris, which live through the winter. From these circum- stances there can be no doubt but that the adipose matter is intimately connected with the function of nutrition and the circulatory system, while the free communication which we have constantly observed to exist between the vesicles seems to favour our opinion that they may serve the office of lymphatic vessels. That they cannot be supposed to answer the purpose of a liver seems evident from the increase and diminution of their contents at certain periods, while their apparent connexion with the Mal- pighian vessels seems to support the opinion we have advanced, more especially if these be regard- ed as uriniferous rather than as biliary organs. Circulatory system. — It was formerly sup- posed that there was a total absence of a circu- latory motion of the fluids in insects, and that the whole body was nourished by a simple imbibition of fluids that occupied the cavities of its different regions. This opinion was strengthened by the circumstance of the air- vessels being distributed to every separate structure and ramifying extensively even upon the most delicate organs, a fact so remarkable that it appeared entirely to obviate the necessity for a motion of the fluids, and led to the pro- mulgation of Cuvier's beautifully ingenious theory, that as the blood could not be carried to be aerated in a separate organ or lung, the air was in consequence brought into contact with it throughout the whole body. But the dis- covery of Carus in 1827 of an actual motion of the fluids, and subsequently the discovery by Straus Durckheim of a structure in the dorsal vessel, which clearly indicates the true use of this organ as a centre of circulation, have sufficiently shown that insects do not differ from other animals in the absence of a circulation of their fluids, whatever modifica- tions may exist in the form and situation of the organs by which it is accomplished. The heart or great dorsal vessel (fig. 433, A) is an elongated tapering organ, which, in every insect, occupies the middle line of the dorsal surface of the body, and extends from the posterior part of the penultimate segment of the abdomen, through the thorax, into the first segment or head of the animal. That portion of it which is situated in the abdominal region is the proper analogue of the heart of other other animals, and is composed of a certain number of separate compartments or chambers (a). It is distinctly muscular, and is of con- siderable diameter, and is that part which is actively employed in circulating the blood. The other part which extends through the thorax is much narrower than the preceding, and is not divided into chambers, but is one conti- nuous vessel that becomes gradually narrower as it passes through the thorax to the head, where it is divided into separate branches (B). This part is less actively employed than the abdominal, being only the great vessel through which the blood is sent from the muscular heart to the system, and, consequently, repre- sents the aorta. In the structure of the abdo- minal portion or true heart we recognize three separate coats, two of which are most distinctly marked, and form the substance of the organ ; but the third or external one is very delicate and not easily observed. Straus Durckheim recognises but two distinct structures, the INSECTA. 977 Fig. 433. A, dorsal vessel or heart of Lucamis cermis. a, the valves or chambers ; b, b, the lateral mus- cles ; c, the supposed auricular space around the vessel. B, the division into vessels of tlw anterior or aortal portion, of the dorsal vessel in the larva of Vanessa urticce. C, interior of the dorsal vessel ( Straus ). a, interior of the valve, showing the transverse fibres; b, the auriculo -ventricular opening and valve into the chambers of the vessel ; c, semi- lunar valve ; d, inter-ventricular valve. internal one (C, a) formed of a transversely folded and striated membrane which is thickest towards the middle of each chamber, and an external one formed of strong, smooth, mus- cular, longitudinal fibres. Burmeister* has suggested that these may be only two layers of one muscular structure, and that the presence of a structureless lining or inner membrane must then be presumed, although it be too delicate to be actually detected by observation. The third or external coat is a transparent struc- tureless membrane which covers the outer ' * Op. cit. p. 156. VOL. II. surface of the heart, and is extended directly over it without following the reflexions inwards of the muscular coat, where it forms the valves or separations between the different chambers. The division of the organ into separate cham- bers is effected by means of an intussusception or reflexion inwards and forwards of the whole muscular structures. A portion of each side of the heart is first extended inwards so as very nearly to meet a corresponding portion from the opposite side, and then reflected back- wards forms, according to Straus,* the inter- ventricular valve (d), which separates each chamber from that which follows it. Posteriorly to this valve, at the anterior part of each cham- ber, is a transverse opening or slit (i), the auficulo-ventricular orifice, through which the blood passes into each chamber, and imme- diately behind it is a second but much smaller semilunar valve (c), which, like the first, is directed forwards into the chamber. It is between these two valves on each side that the blood passes into the heart and is prevented from returning by the closing of the semilunar valve. When the blood is passing into the chamber the inter-ventricular valve is thrown back against the side of the cavity, but is closed, when, by the contraction of the trans- verse fibres, the diameter of each chamber is narrowed and the blood is forced along into the next.cbamber. The number of these openings and chambers in different species of insects does not yet appear to have been satisfactorily ascertained. Straus has figured nine chambers in Melolontha, and consequently eight pairs of openings, but we have not been able to observe more than seven pairs of openings in Lucanus cervus, in which the anterior pair is almost hidden at the commencement of the aorta. Burmeisterf states that he could not find more than four pairs of openings in the larva of Culosomu, while he remarks that according to Midler's description of the heart in Pliasma there appears to be but one pair in that species. In Bombits terrestris we have as yet detected but five pairs, but we nevertheless suspect that these discrepancies, or apparent differences in the number of these openings, arise less from so great a diversity in the actual number than from some of them being overlooked during dissection, since we have invariably found eight pairs in Sphinx ligustri, both in the larva and perfect -state, as well as in other Lepidoptera ; while in the Bombus examined by us the dissection was not so carefully made as to enable us to state positively that there are not more than we have mentioned. The external form of the chambers in the very thick and muscular heart of Lucanus is shown in the drawing we have given of this structure. When the heart is examined by transmitted light, there is seen around it a bright space (A, c) in which we have observed the blood flov\irig very freely in living specimens of Agrion, and which we regard with Straus as an auricular cavity, apparently bounded by a loose membrane, and * C'onsiderat. &c. p, 356. f Op. cit. p. 154. 3 s 978 INSECTA. into which the blood is received both in return- ing backwards from the head and thorax and laterally from the sides of the abdomen. We have observed a similar space in many insects, particularly in Asilus crabroniformis (Jig. 434, D), and also in Bombus terrestris. Fig. 434. One valve of the heart of Asilus crabroniformis. a, the chamber; b, the lateral muscles; c, the auricular space ; the arrows denote the course of the blood. In this insect we have observed the fibres of the heart crossing each other in an oblique di- rection, forming as it were a series of festoons around the posterior part of each chamber. These, like the transverse fibres observed in Melolontha by Straus, contract the diameter of each chamber, and extend the vessel. Be- sides the proper muscular structure of the heart itself, there are attached on each side of the organ several sets of muscular fibres, arranged in pairs along the upper and under surface of each chamber. Each set of these fibres, con- verging to a tendon, and passing outwards, forms a triangular muscle (A, b, b), which is attached to the lateral surface of each seg- ment. These, which have been called the wings of the heart, assist by their contraction to shorten and expand the chambers at the auricular, or receiving period of the heart's mo- tions, while, as just explained, the transverse and diagonal muscles occasion the ventricular, by their contracting and narrowing the diameter of each chamber. It is between the upper and under set of the lateral muscles that we believe the auricular space to exist, bounded by a de- licate membrane. The thoracic or aortal por- tion of the heart commences at the anterior part of the first abdominal segment, where the organ bends downwards to pass under the metaphragma, and enter the thorax. When it has entered that region it immediately ascends again between the great longitudinal dorsal muscles of the wings, and passes onwards until it arrives at the posterior margin of the pronotum ; it then again descends and con- tinues its course along the upper surface of the oesophagus, with which it passes beneath the cerebrum, anterior to which, and immediately above the pharynx, it is bifurcated and divided into several branches, as formerly noticed by us in the sphinx.* Previously to our notice, how- * Phil. Trans. 1832, p. ii. p. 385. ever, Carus had seen the course of the blood in the head of insects following directions cor- responding to the situations in which we have been able to trace a distinct division of the aorta into vessels. We have found a similar division of the aorta into branches in several species of Coleopterous insects, as in Meloe, Maps, and Timarcha, although we have omitted to trace it in Lucanus. In the Sphinx and Vanessa urticce, immediately after the aorta has passed beneath the cerebrum it gives off laterally two large trunks, which are each equal in capacity to about one-third of the main vessel. These pass one on each side of the head, and are divided into three branches, which are directed back- wards, but have not been traced farther in conse- quence of their extreme delicacy. Anterior to these trunks are two smaller ones, which appear to be given to the parts of the mouth and an- tennae, and nearer the median line are two others, which are the continuations of the aorta. These pass upwards and are lost in the integuments. The whole of these parts are so exceedingly delicate that we have not as yet been able to follow them beyond their origin at the termina- tion of the aorta, but believe them to be con- tinuous with very delicate circulatory passages along the course of the tracheal vessels. It is in the head alone that the aorta is divided into branches, since throughout its whole course from the abdomen it is one continuous vessel, neither giving off branches nor possessing la- teral muscles, auricular orifices, or separate chambers. In the larva state it is far more difficult to recognise the true structure of the vessel by actual dissection than in the perfect, because the valves are only in a rudimentary condition. But it is easy to observe it in the bodies of living transparent specimens, as done by Carus, Wagner, Bowerbank, and others in the Ephemerida: and Agr'wnidm, in which not only the form of the valves and motions of the vessel are distinct, but also the abundance of globules that circulate in every direction. Even in some of the opaque-bodied maggots of Dip- tera we have seen the form of the valves very distinctly through the tegument in the eight posterior segments. When viewed in that state each chamber appears to be much narrower at its anterior and posterior extremity than in its middle (jig. 358, D), and the valves formed by the reflexion of its parietes inwards, although distinct, are very small. Near the middle of each chamber there is attached on each side a narrow muscle, which passing backwards is attached to the anterior margin of each seg- ment. Between the muscle and the heart in each segment, a large tracheal vessel crosses to anastomose with its fellow on the opposite side, and on each side of the dorsal vessel, nearly in the course of the lateral muscles, there is a faint indication of a line which seems to form the boundary of what we regard as the auricular space in which the blood is collected before passing into the chambers, of which there are eight very distinct ones in these larvae. The motion and course of the blood, as will be seen from the above account of the structure of the chief organ of the circulation, is first INSECTA, 979 directly forwards in the middle line of the body, and then backwards by the sides of the thorax and abdomen, to the lateral and pos- terior parts of the heart, into which it is re- ceived, by means of transverse currents in each segment, through the auricular space and ori- fices. This course, as discovered by Carus, is indicated in the description and diagram given in a former part of this work.* The blood, which is usually of a very transparent greenish or yellowish colour, is filled with a great num- ber of little particles, which were described by Carus as oblong or oval, but more correctly by Mr. Bowerbank f as flattened oat-shaped masses, which retain their form while circu- lating through the body, but like the particles of blood in Vertebrata become globular imme- diately they are brought into contact with water. It is stated by Burmeister J that they vary in diameter from J.jth to ^th of a line, but they differ also in size in the same individual, and are. often rough or tuberculated as noticed by Edwards,§ and as distinctly seen in the blood of Sphinx ligustri. The motions of the blood, ren- dered perceptible by the presence of these par- ticles, was first observed by Carus in the aqua- tic larva of Ephemera, in which, as in other aquatic transparent bodied larvae, the particles are very distinct. Baker|| and some of the older observers in this country had long before seen motions of the fluids in the limbs of some in- sects, but Carus first discovered the existence of a complete circulation. Cams saw the blood distributed in several streams from the aortal «xtremity of the dorsal vessel in the head re- turning in currents, that entered the base of the antenna.' and limbs, in which it formed loops, and then flowing into the abdomen entered the heart at its posterior extremity. Wagner^] con- firmed Carus' discovery, and added some new observations. He saw the blood flowing back- wards in two venous currents, one at the sides of the body and intestine, and the other along- side of the dorsal vessel, and he discovered that the blood not only entered at the ex- tremity of the dorsal vessel, but also at the sides in each segment, at the valves discovered by Straus. Both Carus and Wagner, however, believed that the currents of blood observed by them were not inclosed in distinct parietes or vessels. Mr. Bowerbank,** in repeating these observations, saw also the blood distributed by the dorsal vessel forming loops in the antennas and limbs, and then passing backwards m la- teral and transverse currents, enter at the valves into the dorsal vessel. And he also observed and clearly denned the structure and action of the valves. He discovered, however, that the currents of blood along the sides of the body are really inclosed in distinct parietes, and do not flow in the common abdominal cavity, * See Article CIRCULATION, vol. i. p. 652., fig. 325. t Entomol. Mag. vol. i. p. 244. $ Op. cit. 404. $ Art. Blood, vol. i. p. 408. || On the Microscope, vol. i. p. 130. t Isis, 1832. ** Entomological Mag. vol. i. April, 1833, p. 239. as previously supposed, the boundaries of the vessels inclosing these currents being clearly definable. He has also expressed his belief that a " much greater portion of the circulation than we can clearly define is carried on within given vessels, as the blood may frequently be seen flowing in curved and other lines, and con- fined within very narrow limits, but so deeply seated amidst the muscles and intestines as to- tally to prevent the boundaries of the current from being clearly observed." We are ourselves most distinctly of the same opinion, having formerly, through the kindness of Mr. Bowerbank, been allowed to examine the circulation in Ephemera by means of his powerful microscope. We believe also that we have seen distinct vessels passing transversely across the dorsal surface of each segment, in the direction of the anterior part of each chamber of the dorsal vessel, in the large pupa of Acherontia Alropos and Sphinx ligustri,* but whether these are vessels returning to or distributed from each chamber, as we are most inclined to believe, is not cer- tain. If they be not vessels distributed from the heart, it is a somewhat curious circumstance that the whole of the blood should be first sent to the head of the insect, and the viscera of the abdominal region be nourished only by the returning blood, which has in part passed the round of the circulation. The only instance in which vessels had previously been supposed to be distributed directly from the heart in the abdomen was pointed out so long ago as 1824 by Professor Muller,f who discovered a con- nexion of the oviducts with the inferior surface of the organ in many insects ; but these were afterwards believed by Carus, Treviranus, Wagner, and Burmeister to be only ligamen- tous connexions. We have observed these con- nexions in many insects, and certainly believed, when we first noticed them, without being aware that they had previously been seen by Midler, that they were vascular structures. We have traced them, especially in the Cardbidd. into direct connexion with the organ, but have been unable to observe at what point the cavity of the ovarial tubes commences, or where the supposed ligamentous portion begins. We have seen these connexions not only in the perfect insects but also in the larvae, more espe- cially in the males of Sphinx ligustri and Odunestis potatoria. In these larvae the two oblong testicles, not united into one mass as in the perfect state, are each attached, side by side, by two short filaments to that chamber of the dorsal vessel which is situated in the ninth segment. One of these attachments proceeds from the anterior and the other from the pos- terior part of each testicle. Now, if these at- tachments be not distinct vessels, it is remark- able that these glandular and secretory organs should always be connected by mere ligaments with the great circulatory organ, since, if the object of their connexion were merely to retain them in their place in the abdomen, it would * Dr. Roget's Bridgewater Treatise, vol. ii. p. 245. t Nova Acta Nat, t. xii. 2. 980 INSECTA. probably be as well answered by an attachment to any other part. These considerations certainly lead us to hesitate to admit that they are mere ligaments. Whatever be their nature, as Muller has observed, their existence is indubitable. Besides the parts now described, there is also another which is connected with and forms part of the vascular system, but the ex- istence even of which has hitherto been almost overlooked. This is a distinct vascular canal, which is extended along the upper surface of the abdominal portion of the cerebro-spinal cord in perfect Lepidopterous insects, and which we have traced from the thorax to the termination of the cord. We have designated this structure the supra-spinal vessel. It is placed immediately above the cord, and is covered by transverse muscular fibres, which exclude it from the common abdominal cavity, and give to the whole cord, when removed from the body and examined by transmitted light, a flocculent appearance. This appearance was first noticed by Lyonet,* but the vessel between it and the cord was not detected by him. It was subsequently figured and described by us in the Sphinxrf and the whole of our recent observations^ have confirmed the opinion we then entertained of it. It is a most distinct structure in the abdomen of the Sphinx, and niay be readily seen after the abdominal cord has been carefully removed from the body with its surrounding structures and placed for some time in spirits of wine. We believe this vessel to be the chief means of returning the blood from the middle and inferior portion of the body to the posterior extremity of the dorsal vessel or heart, and that it is analogous to a structure which we have found to be a supra- spinal vessel § in the Scorpion and Centipede, that had previously been supposed to be a loose and easily detached portion of the nervous system, but which is now proved to belong not to the nervous but to the vascular structures. We are strongly inclined to suspect that this supra-spinal vessel in insects is connected with the anterior portion of the dorsal vessel or aorta, in a manner similar to the connexion which was shown by Mr. Lordfl to exist be- tween the corresponding structure and the heart in Myriapoda. (See Myriapoda.) We believe also that we have seen a corresponding vessel in the larva of the Sphinx, but of so delicate a struc- ture as almost always to elude detection. It will thus be seen that the blood certainly flows in distinct vessels, at least in some parts of the body in perfect insects, and that vessels exist even in the larva. But although a circulation of the blood has been seen by Carus, Wagner, and others in many perfect insects, it has been shown only in the appendages of the body, and in those chiefly in recently developed specimens, while it has been supposed to move only in in- * Recherches sur l'Anat. et lesMetam.de diffe- rentes Especes d'Insectes. Paris, 1832, p. 505, pi. lii. fig. 18. and pi. liv. fig. 2. t Phil.Trans.p. ii. 1834,p.395, pi. xiv. fig.9(a). } Medical Gazette, March 17, 1838, p. 973. § Id. March 17, 1838, p. 971. U Id. March 3, 1838, p. 893. tercellular spaces and not in distinct vessels. This opinion, however, is now invalidated by our discovery of a supra-spinal or great ventral vessel. A motion of the fluids has been seen by Carus in the wings of recently developed Libellulida, Ephemera lulea, and E. margi- vatu, and Chrysopa perla; among the Coleop- tera in the elytra and wings of Lanipuris italica and L. splendidula, Melolonlha solstitiulis, and Dyticus. But Carus was unable to detect it in the wings of Orthoptera, although, accord- ing to Humboldt,* Ehrenberg has seen it in a species of Mantis, and Wagner in the young of Nepa cinerea and Cimex tectularius among the Hemiptera ; but it has not yet been ob- served in the Hymenoptera. Burmeister has seen it in Eristulis tenax and E. nemorum among the Diptera, and Mr. Tyrrel f in Musea domestka as well also as in Geop/iilus and Li- thobius forficatus in the Class Myriapoda. In addition to these Mr. Bowerbank has seen it in one of the Noctuida, Phlogophora metictt- losu% in the Order Lepidoptera, in which it was seen also in the rudimental wings of some pupae by Carus. Some of the most interesting observations that have yet been made upon the motions of the blood in these organs are those of Mr. Bowerbank § in Chrysopa perla. Mr. Bowerbank found that in the lower wing of this insect the blood passes from the base of the wing along the costal, post-costal, and externo-medial nervures, outwards to the apex of the organ, giving oft' smaller currents in its course, and that it returns along the anal or inferior nervure to the thorax. He states that the blood occupies the chief part of the cavi- ties of these nervures, in each of the largest of which is a very small trachea. From this statement it has been rather hastily concluded that the nervures of the wings are only venous trunks, or passages for the circulatory fluids, and are not formed, as hitherto supposed, chiefly by ramifications of the tracheae. He found tracheae existing in the larger of these cavities, which measured only j^th of an inch in diameter, while the cavities themselves mea- sured 3<|s of an inch ; but in others the tracheae measured ,3TOth, while the cavity measured only 305th. He states also that the tracheae very rarely give off branches while passing along the main nervures, and that they lie along the canals in a tortuous direction. In consequence of these most interesting observations we have examined the wings of some dried specimens of this in- sect, and have found that there exists, as Mr. Bowerbank remarks, a very large and perfectly transparent space around the tracheae, which is more or less distinct in different specimens, but in a few instances is not observable. But we have invariably found that the tracheae not only exist throughout the whole of the ramifications of the wings, but also give off branches at every ner- vure or space along which the fluid passes. * Burmeistcr's Manual, p. 408. t Proceedings of the Royal Society, Jan. 15, 1835. % Entomological Magazine, vol. i. April, 1833, p. 243. $ Op. cit. vol. iv. Oct. 1836, p. 179, pi. xv. Now the opinion to which we have been led by our examinations of dried specimens, as we have not been so fortunate as to obtain living ones, since the commencement of these observations, is, that every nervure contains a distinct tra- cheal or air-bearing vessel, and that the free transparent space by which it is surrounded, and which is not discoverable by the naked eye, but only by the microscope, constitutes alone the proper circulatory passage ; that the trachea;, which are obvious to' the naked eye, do not simply lie loosely in these spaces, but that the spaces lie chiefly at their sides and under-surface. These opinions have been de- rived from examinations of transverse sections of the wings of the Chrt/sopa, at parts in which, on a previous examination of the surface of the wing, we have seen both trachea? and the spaces around them. On cutting the wing across at these parts, and then examining the edges, we have invariably found the trachea? hollow, unyielding tubes, while the free spaces on each side, which appear as if bounded by the upper and under membrane of the wing, have appeared collapsed, and almost or com- pletely closed, so as scarcely to exhibit any appearance of hollow spaces. On examining the wing of a dried specimen of one of the Lepidoptera, Gonepteryx Rhamni, by trans- verse sections, we have in every instance found the nervures formed of hollow unyielding tubes, with all the characters of true tracheal vessels, but have not been able to detect the proper circulatory spaces at the sides of these nervures, most probably owing to their dried and col- lapsed state. From these facts we are led to express an opinion which has been long enter- tained by us, that the course of the blood, whether simply along intercellular spaces, or bounded by distinct vessels, is almost inva- riably in immediate connexion with the course of the tracheae. This opinion is founded upon the circumstance that nearly all the observations that have hitherto been made have shown that the currents of blood in the body of an insect are often in the vicinity of the great tracheal vessels, both in their longitudinal and transverse direc- tion across the segments, and it is further strength- ened by Mr. Bo wei bank's observations on the course of the blood in the wings. During his observations Mr. Bowerbank observes that he " has used every endeavour to discover, if pos- sible, whether the blood has proper vessels, or only occupied the internal cavities of the ca- nals ; and that he is convinced that the latter is the case, as he could frequently perceive the particles not only surrounding all parts of the trachea;, and occupying the whole of the in- ternal diameter of the canals, but it frequently happens that globules experienced a momen- tary stoppage in their progress, occasioned by their friction against the curved surface of the tracheae, which sometimes gave them a rotatory motion." He remarks also that the usual course of the blood through the canals is in one conti- nued stream, without pulsatory motion, ex- cepting only when the insect under examination is struggling to escape, when the continuity of the stream is broken, and there are occasional oscillations, of which he observed, in one in- CTA. 981 stance, in a vessel within a space or about one- fiftieth of an inch, twenty-one oscillations in a minute ; and in another, in the same space, so many as eighty-four. He observed also in in- sects that had been captured and in confine- ment for several days, that the motions of the fluid became exceedingly languid and almost entirely ceased. The se observations are exceed- ingly interesting in reference to the genera! velocity of the circulation, and the means by which it is carried on in the wings. The entire absence of pulsations is remarkable, as it com- pletely identifies these vessels as veins, since it is well known that the circulation is carried on through the body by means of regular pulsa- tions of the dorsal vessel. The number of these latter pulsations varies greatly in different insects. Thus llerold found from thirty to forty in a minute in a full-grown caterpillar, and from forty-six to forty-eight in a mucli younger one; Suckow ob- served but thirty, in the same space of time, in a full-grown caterpillar of Qastropacha pini, and eighteen only in its pupa state. But in one in- stance, when the insect was in a state of the most violent excitement, we have counted one hundred and forty-two in a female of Anthophora re- turn. In a number of these insects captured just after they had left their hybernacula in the month of April, and confined for some time in a breeding-cage, we have found that the num- ber of pulsations varies, as might, a priori, be supposed, according to their state of excite- ment. Thus on exposing the dorsal vessel in the morning, before the insects had been excited, we found the number of pulsations was about eighty per minute ; at ten o'clock, when they had become active, the number of pulsations ranged from one hundred to one hundred and ten ; but at three o'clock in the afternoon, when the insects were quite lively, and had been exposed to the sun for an hour or two, the number of pulsations amounted to one hundred and forty; while on another occasion, on a cold dull morning, when the bees were languid, the number of pulsations did not exceed seventv- five in any specimen that was examined. It has usually been supposed, since the discovery of a circulation in insects, that the pulsations are more frequent in the larva than the perfect state ; but this certainly is not the case, if the mean number of observations in the two states be compared. Thus in a series of observations made by us on the Sphinx ligustri,* from the fourth day after the larva had left the egg until the perfect insect was developed, it was found that before the larva cast its first skin the mean number of pulsations, in a state of moderate activity and quietude, was about eighty-two or three per minute ; before casting its second skin eighty-nine ; while before casting its third it had sunk down to sixty-three ; and before its fourth to forty-five, while previously to leaving its fourth, and before it had ceased to feed, pre- paratory to entering the pupa state, it was not more than thirty-nine. Thus the number gra- dually decreases during the growing larva state, but the force of the circulation is very much augmented. Now when the insect is in a state * Phil. Trans, p. 2, 1837. 982 INSECT A. of perfect rest, previously to changing its skin, the number is pretty nearly equal at each pe- riod, being about thirty. When the insect has passed into the pupa state it sinks down to twenty-two, and subsequently to ten or twelve, and after that, during the period of hybernation, it almost entirely ceases. But when the same insect which we had watched from its earliest condition was developed into the perfect state in May of the following spring, the number of pulsations, after the insect had been for some time excited in flight around the room, amounted to from one hundred and ten to one hundred and thirty-nine; and when the same insect was in a state of repose, to from forty-one to fifty. When, however, the great business of life, the continuation of the species, has been accom- plished, or when the insect is exhausted, and perishing through want of food or other causes, the number of pulsations gradually diminishes, until the motions of the heart are almost im- perceptible. Insects, then, do not deviate from other animals, as has been supposed, in re- gard to their vital phenomena, although it has been somewhat curiously imagined that the nutrient and circulatory functions are less active in the perfect than in the larva condition. This supposed inferiority has been attempted to be accounted for on the hypothesis that as insects no longer increase in size after entering the perfect state, there is but little expendi- ture or waste of body, and that, consequently, they must require less nourishment. But we have elsewhere shown * that the expenditure of the body, whether in the larva or perfect state, is in the ratio of the amount of activity and length of life of the insect, while it will be remembered that those insects which exist but for a short time in the perfect state, and take little or no food, invariably have a supply of nourishment stored up within their own bodies, in immense accumulations of adipose matter; and that those which exist for a lona; period have within themselves only a small quantity of nourishment, but are by no means sparing in the quantity of food daily consumed by them, being, as they often are, some of the most voracious of the insect race. Organs of respiration. — All perfect insects, whether inhabitants of air or water, breathe air alone; but some larva?, that are constant in- habitants of water, respire the air which is me- chanically mixed with the water, by means of branchias ; but respiratory organs in the form of trachea; (fig. 435) are almost as extensively distributed throughout every part of their bodies as in the perfect insects. We shall divide the respiratory organs into external and internal. The external are of three kinds, spiracles, tra- chea, and branchia. The internal are either simply tracheal, or tracheal and vesicular. The spiracles are apertures situated along the sides of the body communicating directly with the internal respiratory organs. They are usually nine in number on each side. In Hy- menopterous larva? there are ten. Each spi- racle consists of a horny ring, generally of an oval form, within which is a valve formed of a * Phil, Trans, p. 2, 1837, Fig. 435. Portion o f a tracfseal vessel of the larva of Vanessa ■urticce, shewing, a, the spiral fibre j and b, the loose investing covering. (Netvport, Phil. Trans.y series of converging fibres, and which opens perpendicularly in its long axis, guarding the external entrance. At a little distance within this valve the spiracle is somewhat enlarged, and there is a second valve of a more com- plicated form. This has already been noticed in our account of the muscular structure, but we must again describe it in connexion with the respiratory organs. The anterior half of this inner or second valve is strong, immovable, and of a horny texture, of the colour of tortoise- shell. It is thin and lunated at its margin. The posterior half is thick, rounded, and freely moveable, and closes- on the anterior like a cushion or pad. This is the structure of the spiracle in the Sphinx and most other insects. But m some, in which the spiracle is concealed beneath a portion of the skeleton, the horny external ring is absent, and instead of it the entrance, or margin of the spiracle, is merely a little thickened and fringed with short hairs. This description of spiracle exists in the pro- thorax of some Coleoptera and Orthoptera as in Gryllolalpa, in which one portion or lip overlaps the other, thus forming as it were an outer valve or lid. In other instances,as in the Lamellicornes, the spiracles of the abdomen are very minute and circular, and their open- ing appears to be cribriform, or at most only very minute, and surrounded by short hairs. In others, again, as in some larvae, the spiracles consist of a broad margin with a narrow middle space and central aperture that leads immediately into the tracheal vessel, the open- ing into which is exceedingly small. The size of the spiracles in different parts of the body varies very much in different insects. Those of the abdomen are always much smaller than those of the thorax, and the most posterior ones, which were of great importance in the larva INSECTA. 933 state, are almost or entirely imperforate in the perfect. The reason for this appears to result from the changes that take place as regards the region of the body in which respiration is chiefly carried on in the two states of the insect. In the larva state respiration is carried on chiefly in ihe abdominal region, but in the perfect the chief part of the body con- cerned is the thorax. It is through the tho- racic and first pair of abdominal spiracles that nearly the whole of the air enters and is ex- pired at each act of respiration, and conse- quently it is found that the spiracles in those parts are very much larger than in the abdo- men. The largest spiracle is usually the pro- thoracic, of which we have an example in Geotritpes and Gryllotalpa, and the next Largest, as in Geotrupes, is the first abdominal. The situations in which the spiracles are placed also vary considerably in different insects. In Coleoptera and Orthoptera the first pair are si- tuated in the membrane between the pro- and meso-thorax, and the remaining ones in the meso-* and meta-thorax and following seg- ments of the abdomen. There is also a similar arrangement of the spiracles in Hemiptera. But in other insects, as in the larvae of Lepi- doptera, the first spiracle is situated in the pro- thorax, and the remaining eight pairs in the fifth and succeeding segments to the twelfth ; while in the larvae of Hymenoptera, in which there are ten spiracles on each side, they are placed in the second, third, fifth, sixth, and succeeding segments to the twelfth. The second form of external respiratory or- gans, as Burmeister remarks, are simply elon- gated spiracles, and are found only in those insects which reside almost constantly in the water, but breathe pure atmospheric air, for which purpose they come to the surface of the water at intervals to respire. They are short horny tubes, which in some instances are sur- rounded by plumose setae. They are always open at their extremity, and in general project beyond the body. They are chiefly met with in the aquatic Hemiptera, as in Nepa (Jig. 352) and Runatra, and are usually two in number, projecting from the extremity of the abdomen. In Nepa they are about half the length of the body, and in Ranatra as long as the whole body itself. It is through these tubes that the whole of the respiratory function is performed, and the air both inspired and ex- pelled. They exist also in the larvae of the Dyticida and Hydrophilida:, in which they are the only respiratory passages, although it has been thought by some that lateral spiracles exist also in these larvae, as subsequently found in their perfect insects. This form of respira- tory organ exists also in the aquatic larvae of some Diptera, as in the rat-tailed maggot, Eristalis, and the larva of Stratiornys. In the latter instance the insect supports itself at the surface of the water by a coronet of radiating setae, in which it includes a bubble of air, and descends with it to the bottom of pools for the purposes of respiration, and comes again * Straus. to the surface for a fresh supply when the store it has carried with it is exhausted. These or- gans are thus distinct from those by means of which the insects respire the air mechanically mixed with the water. Branchia constitute the third form of ex- ternal respiratory organ. This form is met with only in the larva and pupa state. These organs are always situated at a part of the body at which the spiracles are subsequently to exist. They are formed, as in the larvae of Amphibiae, of extensions outwards of the exterior or cuticular surface of the body, and are largely supplied with bloodvessels, and tracheae ramify within them. They are never, as in the gills of fishes, developed internally, excepting when they exist at the anal extremity of the body, as in the Libellulidce, but are extended from the sides as in the Tadpole, being simply expansions of the external surface. We are not aware that cilia have yet been observed on these surfaces, but judging from the analogies of structure and formation that exist between these parts in insects and the analogous ones in the larvae of Amphibia, there seems reason to expect that they do probably exist. The necessity for such structures on the branchiae may, however, be rendered less imperative from the voluntary power which the insect itself possesses of moving the branchiae at pleasure, by which the function of cilia, that of effecting a con- stant renewal of the water in contact with the surface of the organ, is steadily accomplished. It is the belief of most entomologists,* that branchiae absorb the air from the water, and convey it by the minute ramifications of the tracheal vessels, with which they are abundantly supplied, and which terminate in single trunks, into the main tracheae, to be distributed over the whole body, as in insects which live in the open atmosphere. This is supported by the fact that the tracheal vessels, as seen in the transparent bodies of many aquatic larvae, are filled with air; but the subject still admits of enquiry, why in these instances the usual func- tion of branchiae is so far departed from as to allow of the air being absorbed from the water into distinct vessels, to be distributed over the whole body, for the purpose of aerating the fluids, rather than that it should be brought into contact with the blood, and undergo the consequent changes at the surface of the bran- chiae, as in the larvae of Amphibia and Fishes. The branchiae of insects are of three kinds. The first exists in the form of elongated, slender, hair-like organs, collected together in tufts, that originate by single stems, as in the larvae and pupae of gnats.f This form is by far the most common. These filamentous parts are supplied each with a single trachea that is extended throughout their whole length, and which is connected with the great longitudinal tracheae of the body. In a very few instances, branchiae of this form originate separately, and not in tufts, as, according to De Geer,| in the * Burmeister. t Burmeister, op. cit. p. 167. X Mcmoires sur les Inscctcs, vol. iv. pi. 13, fig. 16.19. 984 INSECTA. larva? of Gyrinidte, in which they are arranged along the sides of each segment as short stiff bristles. This form of branchia? is also said to exist in one solitary species of Lepidoptera, Hydrocampa straiiotata,* and perhaps, also, in the other species of the same genus, in which branchia? of this form exist in the neigh- bourhood of false spiracles. The second kind of branchiae exists in the form of flat, oval, or lanceolate plates, extended from the sides of each segment of the abdo- men, where spiracles afterwards exist in the perfect insect. In some instances, as in the AgrionidtB, these plates exist only at the extre- mity of the abdomen. In others, as in the Ephemerida, they exist both at the sides and at the extremity of the body. This form of branchiae is found only in the Neuroptera and Triclioplera. In many of the latter instances these parts possess also the additional function of being the chief locomotive organs of the insect, and remind us strongly of the branchi- form organs of locomotion in the post-abdo- men of many Crustacea. An anomalous insect, recently discovered by Mr. Hogg as a constant inhabitant of the river- sponge, and an account of which was read by Mr. Westwood at a meeting of the Entomolo- gical Society on the 3rd of December, 1838, possesses a third and most remarkable descrip- tion of branchia. This insect, which was re- ferred by Mr. Westwood to the order Neurop- tera, genus Acentropus, Steph. very much resembles the larva of a neuropterous species, and has filiform branchiae extended from the sides of the abdomen, which are distinctly ar- ticulated, and apparently five-jointed. Mr. Westwood informs us that he has distinctly traced tracheae into the branchia?, and that the open extremity of each vessel protrudes from the tip of the branchiae, so that in this respect these organs resemble elongated spiracles. Very few of those larva? or pupa? that pos- sess branchia? have any lateral spiracles, ex- cepting the Culicida. In some of these, as in the common Gnat, both larva? and pupa? breathe by means of large tracheal vessels, extended outwards to some distance from the head and thorax, while the body is also furnished with filamentous branchia?. The larva of Chiro- nomus, remarkable for its blood-red colour, and which breathes through tubes, is furnished in its pupa state with branchia? f at a part cor- responding to that at which the first spiracles are to appear in the perfect insect. The true Libelluiida have neither lateral nor anal bran- chia?, but, according to Suckow and others, breathe by means of branchia? in the colon. But in these insects, as in the Ephemerida. with lateral branchia?, the acts of respiration are also those of progression ; since, although the imbibition and expulsion of water at the anal extremity are regular and constant, even when the insect is remaining perfectly quiet, they are increased both in number and force at every act of locomotion, and carry the body forward * Id. vol. i, pi. xxxvii. t Burmeistcr, p. 167. by darts or sudden impulses. The water is received at the anal orifice by an inspiratory or sucking action, as proved by the circumstance that small particles of substances floating in the water are drawn in with the stream at the anus at each inspiration, and again expelled from it when the water is ejected, and this oc- curs with the greatest regularity. The cavity into which the water is received is a clouca distinct from the proper alimentary canal,, analogous to the respiratory cloaca of the Ho- lothuria and other lower invertebrata. These external organs of respiration all com- municate with elongated trachea?, from which are distributed other branches over the internal structures. In the larva? of all insects these internal respiratory organs are simply ramified tubes, but in perfect insects, and more parti- cularly in volant species, these tubes are di- lated into an immense number of minute vesicles, which not only allow of the most ex- tensive respiration, but also render the body lighter, by enabling the insect to alter its spe- cific gravity during flight. In all insects the vesicles are only dilated trachea?, the structure of which is the same throughout the class. In the larva of the Sphinx and other insects the tracheal vessels consist of two elongated tubes, extended one on each side of the body, and which on their external side communicate by very short tubes with the spiracles, and on their opposite, towards the middle line of the body, give off near each spiracle a large tuft of ves- sels, about twelve in number, which extending inwards are distributed over the different organs within the body. The chief of these are distributed to the alimentary canal, while others pass upwards among the muscles, and ramify most extensively between them, and are given in great abundance to the dorsal vessel. In every segment other branches are extended to the median line above the vessel, and anas- tomose with corresponding branches from the opposite side of the segment. In the head one large branch passes forwards from the pro- thoracic spiracle, and anastomoses with its fellow from the opposite side above the oeso- phagus, behind the brain, and the two thus united then give off four branches, which passing forwards over the brain give off branches that ramify on the surface, and even in the substance of that organ and of the optic nerves. Other branches are given to the muscles of the head, the future antenna?, and the organs of manducation. On the under surface of the body the tracheal vessels dis- tribute themselves among the muscles, as on the dorsal surface, some passing beneath the nervous cord to anastomose with those from the opposite side, while others are distributed to, and ramify extensively over the surface of each gangliated portion ofthe cord, givingoff the most minute branches which penetrate the very sub- stance of the ganglia (fig. 415, i, i), and also that of the nerves themselves, along which other minute branches are extended, so that even the most important and delicate organs of the body are plentifully supplied with tracheal vessels. Other branches of trachea? also pass 1NSECTA. 985 between the fibres of the muscular coat of the alimentary canal, and ramify extensively be- tween the mucous coat and a structure which we have described* as the adipose coat, which lies between the mucous and muscular, as is well seen in the colon and coecum of the puss-moth, Ceri/ra vinula, in the perfect state. It is in this layer that the ramifications of tracheae anastomose very freely, but do not enter the mucous or internal coat. Besides these parts all the secretory and generative organs are sup- plied with anastomosing branches in abun- dance, and trachea; are extended even to the very last joints of the tarsi in the limbs. The only parts into which we have not observed tracheae penetrate are the adipose vesicles, upon which we have not often observed rami- fications, although branches of tracheae are dis- tributed very extensively among them. In the larva state the tracheae are always smaller than in the perfect, compared with the size of the individual, and they are smallest in those apodal larvae of Hymenoptera which reside long in closed cells, as the Anthophura return, in which insect the communications of the tracheae across the body are very distinct, as was shewn long ago by Swammerdam in the larva of the hive-bee. The structure of the tracheae has been des- cribed by Swammerdam, Sprengel, and others. Sprengel has described the structure as con- sisting of an external serous and an internal mucous membrane; inclosing between them a spirally convoluted fibre (fig. 435, a), which is elastic, and gives to the tracheae the appearance exhibited by the tracheae in other animals. The external or serous membrane (b) very loosely surrounds the spiral fibre («). The mucous or internal lining, as we formerly re- marked, and as noticed by Swammerdam, De Geer, Lyonet, and Bonnet, is continuous with, and is thrown off' at the change with the external covering of the larva, and certainly is a distinct membrane, renewed at those periods, although Sprengel believes that it is only a means of connexion between the coils of the spiral fibre, and not a distinct structure. The vesicles, or dilated tracheae, exist in the greatest abundance in volant insects, although they also exist in a much less developed form in the saltatorial. These vesicles exhibit an appearance which was formerly noticed by Swammerdam in Ori/ctes nasicornis, and sub- sequently by Sprengel in other insects. It con- sists of an amazing number of punctured spots, discoverable only under a good microscope, but which, when attentively examined, exhibit somewhat the appearance of perforations. The precise nature of these spots is not well under- stood. Burmeister conceives that they are oc- casioned by the rupture of the spiral fibre during development, and that the spots are the spaces between the broken fibres. But Marcel de Serres and Straus Durckheim deny the existence of spiral fibre in the vesicles, while Suckow and Burmeister contend that it cer- tainly does exist, and we also are of this » Phil. Tians. 1836. opinion. Indeed, when it is remembered that the vesicles exist only in the perfect insect, and are only dilated tracheae, and that the existence of spiral fibre in the tracheae is undoubted, surely its existence can scarcely be questioned in the vesicles, although, probably, it is in an almost atrophied condition. Now the fact that the spots are not observed on the vesicles until the insect has entered the perfect state, was, perhaps, one of the circumstances that led Burmeister to his opinion respecting them ; but that they are not caused by ruptured spiral fibre is proved by the existence of these spots in some of the tracheae that communicate direct- ly with the vesicles, and have not been dilated, and in which the spiral fibre is unbroken. It is also shewn by the circumstance of their not being in a regular series, over the course of the fibres, but distributed thickly and irregularly over the surface of the vesicles, and by their existing in the space between two parallel fibres in the tracheae, and even in the substance of the fibre, as we have seen them in the vesicles of the male of Bombus terrestris. Be- sides this, they are sometimes seen to terminate in an abrupt and remarkable manner in the dilatations of the larger tracheae in the same insect. The results of our own observations lead us to conclude that these spots are not ruptures of the spiral fibre, but are partial per- forations of the vesicles, — that they do not pass through the internal or lining coat, and probably are little cells in the coats of the vesi- cles, through which the circulatory fluid can be freely submitted to the action of the air in the vesicles, as in the minute terminal cells in the lungs of vertebrata. The use of the vesicles, as above remarked, and as formerly suggested by Hunter, appears to be to enable the insect to alter its specific gravity at pleasure, by enlarging its bulk, and thus rendering it better able to support itself on the wing with little muscular effort. That this is the use of the sacs may be inferred from their non-existence in the larva state, or in in- sects that constantly reside on the ground, more particularly in creeping insects ; and it seems further confirmed by the fact that, among volant insects, those have the largest and greatest number of vesicles which sustain the longest and most powerful flight. Thus the vesicles are found most developed in the Hymenoptera, Lepidoptera, Diptera, ;ind some Coleoptera and Hemiptera, in all which, in the larva state, there is not the slightest trace of them. A still further proof that they are for lightening the body is found in Lucanus cervus. In the male of this insect the large and heavy man- dibles and head, but more especially the man- dibles, are not filled with solid muscle, as in the Hydrous and others in which these parts are more in proportion to the size of other parts of the body, but with an immense number of vesicles, which in the mandibles are developed in the greatest abundance in rows from long tracheae, that are extended from one end of the organ to the other, so that the interior is almost entirely filled with vesi- cles. By this beautiful provision these pro- 986 INSECTA. jecling and apparently unwieldy structures are rendered exceedingly light, while their solid exterior fits them for all the purposes of strength required by the insect. The large and apparently heavy body of the humble-bee is lightened in a similar manner. In this insect and others of the same order, the vesicles are fewer but very much larger than in Coleoptera. The lateral trachea; in the abdomen form one continuous chain of dilatations, which are larger in the males of the species (fig. 436) Fig. 436. The lateral and inferior series of vesicular respi- ratory organs in the abdomen of a male individual of Bombus terrestris. ( Newport, Phil. Trans. ) than in the females. The longitudinal tra- chea (a), that pass backwards from the thoracic region, are connected just as they pass through the petiole or thoracico-abdo- minal segment into the abdomen, by a very short transverse branch (/>), which gives off two pairs of minute branches into the ab- domen. The longitudinal trachea? (c) pur- suing their course onwards are dilated, soon after they enter the large first segment of the abdomen, into two enormously expanded vesicles (_/'), above which is placed transversely a third and much larger one, which is formed from the anastomosing branches of the opposite sides of the segment, and is also connected with the little branches given off from the transverse branch (b). Beneath this large vesicle passes the dorsal vessel, and between the tv. o lateral ones (f) the alimentary canal. Besides the branches from the transverse tracheae (6) there are two others from the large tra- cheae (e), which pass longitudinally backwards, one on each side of the oesophagus. That on the left side (e, e) passes as far as the posterior part of the proventriculus, and then turning forwards distributes its branches to that organ. The other on the right (d, d) extends no farther than the anterior part of the proventriculus, immediately behind the crop or honey-bag, upon which it is chiefly distributed. The large vesicle (,/*) is connected with the dilated trachea? in the succeeding segments, and the whole form one continuous irregularly-shaped vesicular cavity, which, along its under surface in each segment, is dilated into a funnel-shaped transverse trachea (g), that anastomoses with its fellow of the opposite side, passing beneath the muscles as in the larva. From the upper surface of the longitudinal canals similar fun- nel-shaped dilatations (i, k) pass over the dorsal surface of the abdomen and anastomose in like manner with those of the opposite side, besides which single undilated ramifications of trachea? (/i) pass inwards on each side and are distributed over the alimentary canal. At the posterior part of the body the vesicular canals communicate directly by a large branch (/), from which large trunks are given to the colon and organs of generation. Thus, then, the use of the vesicles is distinctly indicated, even in the peculiar distribution of undilated trachea? to the whole of the organs of nutrition. The distribution of single ramified trachea? from large vesicles appears to be constant in this order ; it was formerly shown by Leon Du- four* in Scolia hortorum, and we have always found it in the Ichneumonida and other fami- lies. Burmeister states that he has been un- able to ascertain whether this is also the case in Diptera, in which order the vesicles are both large and numerous. According to Marcel de Serresf the Asilida have an immense number of small elongated vesicles on each side. In one species they amount to so many as sixty. Burmeister remarks]; that, in Lepidoptera, the vesicles in the Sphingida and moths are chiefly found in the males, which agrees with our own observations in Hymenoptera. In Acherontia Atropos he states also that the existence of spiral fibre in the vesicles is so distinct as not to be doubted. This is the structure of the respiratory organs in volant insects, but throughout the class, whether in volant or creeping insects, there is always a complete anastomosis of the trachea? on one side of the body with those on the opposite, as has been well exemplified by almost all insect anatomists, Swammerdam, Lyonet, Marcel de Serres, Dufour, Straus, and others. The development of the vesicles begins to take place at about the period when the larva ceases to feed, preparatory to changing into the pupa state. At the time when the larva of the Sphinx enters the earth, and is forming the cell in which it is to undergo its transformation, the longitudinal trachea? of the second, third, fourth, and fifth segments become a little en- larged. In the butterfly, Vanessa urtica, which does not enter the earth, but suspends * Journal dc Physique, Sept. 1830. t Meraoires des Museum, torn. iv. p. 362. X Op. cit. p. 181. INSECTA. 987 itself vertically to undergo its change, the di- latation commences while the insect is spinning the silken hangings from which it suspends itself; so that the changes commence at a corresponding period in both insects. It is in the butterfly that we have most closely watched the development of the vesicles. During the period that the insect remains suspended it makes several powerful respiratory efforts, accompanied by much muscular exertion, and these efforts are continued at intervals until the old skin is fissured and thrown off. It is at this period that the tracheae become much en- larged, as we have found at about two hours after the insect has suspended itself. Meckel observed the sacs soon after the insect has entered the pupa state, but it will thus be seen that the expansion of the tracheae in the for- mation of these sacs commences very much earlier. At about half an hour before the in- sect becomes a pupa we have found the whole of the trachea; more distended, particularly those on the under surface of the thorax, from which branches are given to the legs, so that the elongation of these trachea; is probably connected with the subsequent rapid develop- ment and extension of those organs. At this period the tracheal of the abdomen have ex- perienced but little alteration. It is at the actual period of transformation that all the changes take place most rapidly. At that time the laborious respiratory efforts made by the insect appear greatly to affect the condition of all the organs. VVhen the skin is thrown off, these efforts cease for a few minutes, after which the abdominal segments become short- ened, and the circulatory fluid is propelled forwards, and the wings, then scarcely so large as hemp-seeds, are gradually distended at their base, and at each respiration are perceptibly enlarged, and carried downwards over the under surface of the thorax and first abdominal seg- ments. Carus* attributes the development of the sacs, and dilatation of the trachea;, to the entire closing of the spiracles, and expansion of the air contained within them, which he thinks is increased in quantity during the deve- lopment of the insect. But from the circum- stance that all the trachea are enlarged imme- diately after the insect has entered the pupa state, it seems probable that this enlargement is occasioned simply by the closing of the spiracles, and the expansion of the air within the trachea;, during the powerful respiratory efforts, aided by the receding of the circulatory fluid from the abdomen into the partially de- veloped wings, suddenly removing pressure from the tracheal tubes, which then become distended by the natural elasticity of the air contained within them ; and further, that the subsequent enlargement of these tracheae into distinct bags is occasioned, not by an in- creased quantity of air in the vesicles, as Carus imagines, but simply by a continuance of the same cause that effects the first dila- * Introduction to Comparative Anatomy, trans- lated by Gore, 1827, vol. ii. p. 167, tation of the tracheae, the elasticity of the contained air, since the dilatation appears to keep pace with the gradually decreasing size of the digestive organs, and the spiracles are not permanently closed during the pupa state, respiration being continued at intervals, ex- cepting perhaps in the most complete state of hybernation. In accordance with this opinion we find that, at about half an hour after the change, the pro-thoracic tracheae that ramified over the oesophagus are enlarged to double their original diameter, and have begun to be detached from that organ. At seven hours these changes have been carried much farther. At twelve hours they are still further enlarged, and the principal alteration observed is the diagonal direction of those from the seventh spiracles, which supply the posterior extremity of the digestive stomach, owing to that organ having now become shorter, previously to its subsequent change. At eighteen hours all the trachea; of the head and thorax are still further enlarged, and those from the third spiracle are detached from the cardiac extremity of the stomach, and are more enlarged than the others, and those from the ninth spiracle, in the twelfth segment, which supply the colon, are begin- ning to be distinctly vesicular. At thirty-six hours not only have the longitudinal tracheae and their many branches become dilated, but those distributed to the different viscera have also become vesicular. At forty-eight hours the development of these parts is so far ad- vanced that the whole have assumed the vesi- cular form, and those at the anterior part of the abdomen occupy a great proportion of that region, and the dilatation of others proceeds until within a few days before the perfect insect is developed, before it is completed. The only difference we have observed between the development of these organs in the Sphinx and the butterfly is in the rapidity with which the changes are effected. The Sphinx re- mains many months in the pupa state, during a great part of which time the changes are almost or entirely suspended. The butterfly remains but a few days, and in consequence all the changes proceed with rapidity, which is either greater or less in proportion to the season of the year and temperature of the atmosphere. Function of respiration. — Having dwelt so long upon the structure of the parts concerned in respiration we cannot venture at any length upon the phenomena connected with the func- tion, which properly belong to a distinct sub- ject. (See Respiration.) We would remark, however, that the circumstances connected with it are in many respects particularly in- teresting, while the results are similar to those of the respiration in other air-breathing ani- mals. Thus the acts of respiration consist of alternate dilatations and contractions of the ab- dominal segments, the air entering the body chiefly at the thoracic spiracles, and partly also at the abdominal, during which the dorsal and ventral arches of the abdomen are alternately elevated and depressed, like the ribs of Ver- tebrata. The number and frequency of these 988 INSECTA. respirations vary, as in Vertebrata, according to the degree of activity and state of excite- ment of the insect. Thus when an insect has been subject to long-continued exertion, the acts of respiration are quick and laborious, as every one must have observed in the larger Bombi, when alighting after a long-continued flight. The contractions and extensions of the abdominal segments are then short and quick, and sometimes so labored that the whole ab- domen is shortened and extended like the flanks and ribs of the race-horse, after a long and severely contested race. The number of respirations, when the insect is in a state of moderate excitement, varies also in different species as well as in the different states of the same insect, and at different periods. Thus in the green grasshopper we have noticed from thirty to forty regular contractions in a minute, alternating, at irregular periods, with others more long and deep than the rest. When this insect was much excited the intervals between the long inspirations were longer, and the in- spirations when they occurred were more deep and laborious. When an insect is preparing itself for flight the act of respiration resembles that of birds under similar circumstances. At the moment of elevating its elytra and ex- panding its wings, which are, indeed, acts of respiration, the anterior pairs of spiracles are opened, and the air rushing into them is ex- tended over the whole body, which, by the ex- pansion of the air-bags, is enlarged in bulk, and rendered of less specific gravity, so that when the spiracles are closed at the instant the insect endeavours to make the first stroke with and raise itself upon its wings, it is enabled to rise in the air, and sustain a long and power- ful flight with but little muscular exertion. In the pupa and larva state respiration is per- formed more equally by all the spiracles, and less especially by the thoracic ones. The frequency of the acts of respiration seem to bear some relation to the expenditure of muscular energy by the insect in a state of activity. All volant insects respire a greater quantity of air in a given time than terrestrial, and both these in their perfect than in their larva state. Thus in the common hive-bee we have noticed from one hundred and ten to one hundred and sixty contractions of the abdo- minal segments in a minute, while in a less active state, when the insect was entirely un- disturbed, the acts of respiration seldom amounted to one-half that number. In an exceedingly wild and irritable little bee, An- thophora retusa, which dies exhausted from the most violent excitement and exertion, in the course of an hour or two, after being captured and confined during summer, the acts of re- spiration are often performed so rapidly that, on one occasion on which we observed them, they amounted to two hundred and forty in a minute, and of course it was only by the closest atten- tion that their number could be ascertained. Next to the pupa state, a state of common repose is that in which insects respire with the least frequency. When a perfect insect or a pupa has remained for some time undisturbed, its respiration becomes gradually slower and slower, until at last it is scarcely perceptible. Thus, in the midst of winter, at a temperature of the atmosphere a little below freezing, we were unable to detect more than the very slightest trace of respiration during two or three days, and even at the expiration of fourteen days the quantity of carbonic acid gas formed was very small. But when the insect was re- moved into a much warmer atmosphere it began again to respire more freely, and the quantity of carbonic acid produced in a given time was considerably increased. In a speci- men of Botnbus terrestris, which had remained at rest for about half an hour, the respirations had become deep and laboured, and were continued regularly at about fifty-eight per minute. At the expiration of one hundred and forty minutes, during which time the in- sect remained in a state of repose, the respi- rations were only forty-six per minute, and at the expiration of one bundled and eighty mi- nutes they were no longer perceptible. This same insect, when first captured, and in a state of moderate excitement, respired at the rate of one hundred and twenty-five inspirations per mi- nute. We have noticed the like circumstances in a female Sphinx ligustri, which after it had been excited for a short time in flight breathed at the rate of forty-two respirations per minute, while after it had remained at rest about seventy-five minutes respired at the rate of only fifteen per minute. Hence the quantity of air deterio- rated by an insect in a given time depends upon the state of activity and condition of life of the individual. In accordance with the frequency, and consequently the quantity of respiration, such are the results. In accele- rated respiration the circulation of the fluids is increased, and in those conditions, noticed in another part of this paper, in which the cir- culation is accelerated, the acts of respiration are at the same time more frequent. The development of heat, which is now found to take place in all insects as in the air-breath- ing vertebrata, depends mainly upon the quan- tity and activity of respiration, and the volume and velocity of the circulation. In Hymenop- tera, in which, as we have seen, the capacity of the respiratory organs is greater than in other insects, and consequently the quantity of air deteriorated in a given time is also greater, the quantity of heat evolved during the process is proportionate to the quantity of respiration. In the larva, in which, in relation to its size, the quantity and energy of respiration are less than in the perfect insect, the quantity of heat deve- loped is also less, so that in the larva? of Hyme- noptera it does not exceed from two to four degrees that of the medium in which the insect is placed ; while in the perfect insect, in a state of little activity, the quantity of heat developed is apparently at its minimum amount at three or four degrees above the temperature of the surrounding medium. But when the same insect is in a state of moderate activity, and consequently is respiring more frequently, it INSECTA. 989 amounts to even fifteen or twenty degrees. In all cases the amount of temperature depends chiefly upon the quantity of respiration. We have seen that in a state of repose the acts of respiration become less and less frequent, and that at last they are scarcely perceptible. In like manner the amount of heat generated is proportionate to the diminished number of respirations, and continues to be lessened until the temperature of the insect has very nearly sunk down to a level with that of the atmo- sphere. There are also other circumstances which moderate the production of heat. When the insect is fasting less heat is generated, even during a state of activity, than when the insect is not deprived of its proper quantity of food. The cause of this deficiency seems readily to be accounted for on the consideration that no new material, the product of digestion, is taken into the general circulation, and requires to be assi- milated with the circulatory fluids, and, conse- quently, there is less change in the chemical condition of the fluids at each respiration, than when the animal is taking its full amount of food. Other circumstances also tend to regu- late the amount of heat. When the insect is respiring rapidly, the power and frequency of its circulation are augmented, and not only is there a greater quantity of gaseous expenditure from the respiratory organs, but there is also a greater amount of cutaneous expenditure, which tends to cool down the insect by evaporation from the surface of its body, and diminish the amount of heat developed. This expenditure is so enormous, as we have elsewhere shown,* that it is more than equal to the quantity of solid matter excreted from the alimentary canal in a given time, and, consequently, is a power- ful means of reducing the temperature of the insect. One very marked difference which ex- ists, in respect to the function of respiration and the evolution of heat, between these air-breath- ing invertebrate and the vertebrated animals is, not in their different powers of generating, but of maintaining their temperature. Insects in their low power of maintaining heat closely resemble the true hybernating animals. Any great or sudden change of temperature in the surrounding medium rapidly reduces the tem- perature of the insect. It is thus seen that a reduction of temperature takes place not only at the period of true hybernation, which insects undergo either in their pupa or perfect state, but also during vicissitudes of the season, as well as during natural repose. On the other hand, it is remarkable that the evolution of heat in insects takes place as rapidly as it becomes reduced. Its increase is perceptible by the thermometer within a very few moments after the insect has begun to respire more rapidly. The explanation of this circumstance must be sought for in the peculiar distribution of the respiratory organs, which are extended over the whole body, and aerate the blood in every part of it at the same instant, the result of which is the immediate evolution of a large amount of heat, from the changes that occur in the fluids * Phil. Trans. 1837, p. 2. in vessels that partake both of the venous and arterial character. Consequently a large amount of heat is liberated instantaneously, whether the oxygen of the atmosphere be ab- sorbed into the circulatory system, or whether the whole of the changes take place, and car- bonic acid be formed in the respiratory struc- tures. The same rapidity with which the heat is evolved from the body accompanies its dimir nution when the quantity of air inspired is lessened. In confirmation of this view with regard to the production of heat being the result of the chemical changes in the air inspired, there is one remarkable circumstance that can- not be passed over. It is the voluntary power which we have found is possessed by some species of generating heat by means of accelera- ting their respiration. We observed this fact in the individuals of a nest of Humble-bees, Bom- bus terrestris, which were confined by us for the purpose of watching their habits. Huber formerly noticed that bees are in the habit of incubating on the cells of their pupa;, before the perfect insects are developed, and we have had ample opportunities of confirming his observa- tions. It was during the time that we were engaged in watching these habits that we dis- covered that bees possess this voluntary power of increasing their temperature. The manner in which the bee performs her incubatory office is by placing herself upon the cell of a nymph that is soon to be developed, and then begin- ning to respire at first very gradually. In a short time the respirations become more and more frequent, until at length they are increased to one hundred and twenty or one hundred and thirty per minute. The body of the insect soon becomes of a high temperature, and on close inspection is often found to be bathed with perspiration. When this is the case the temperature of the insect soon becomes re- duced, and the insect leaves the cell, and ano- ther bee almost immediately takes her place. When respiration is performed less violently, and consequently less heat is evolved, the same bee will often continue on a cell for many hours in succession. During these observations we have, in some instances, found the temperature of a single bee exceed that of the atmosphere more than twenty degrees. Thus when the temperature of the atmosphere was 73° 5 Fahr. that of four female bees, in the act of incuba- tion, was 94° 1. On another occasion when the atmosphere was 72° 5, a single bee, nursing on a single cell, from which a per- fect insect was developed about eight hours afterwards, afforded a temperature of 92° 3, the bulb of the thermometer being placed between the abdomen of the bee and the cell. The insect was then breathing at the rate of one hundred and twenty respirations per minute. In another instance, the temperature of the atmosphere being the same, that of ano- ther bee in the act of nursing was 94° 5. This extreme amount of heat was evolved en- tirely by an act of the will in accelerating the respiratory efforts, a strong indication of the re- lation which subsists between the function of respiration and the development of animal 990 INSECTA. heat. These curious facts tend much to con- firm the opinion as to the chief origin of animal heat, but for farther illustration of this interest- ing subject we must refer our readers to the article Respiration. Organs of generation. — These parts have already been treated of to some extent in a preceding article, (Generation, Organs of,) and the forms which they assume in different orders, more particularly those of the male organs, having in part been described, we shall only briefly allude to them on the present occasion, in consequence partly of the great length to which this paper has already been ex- tended, and partly that we shall necessarily return to this subject, more especially with re- ference to the functions of these parts, in de- scribing that class of Articulata, which in every respect are so closely related to insects, the Myriapoda, to which we must refer. In our observations on the skeleton we have shown that the terminal segments of the body invariably form part of the external organs of generation. The long ovipositor of the Chry- sidida, composed of four distinct annuli, retrac- tile within one another, and even within the proper abdomen itself, are only the terminal segments of the body, which is thus made to consist of fewer, but proportionately larger annuli than the abdomen of those in which so many segments are not employed in the forma- tion of the generative organs. A corresponding structure is also seen in the Panorpidce, in which the separate annuli, not retractile to so great an extent as in the Chrysididce, but capa- ble of being extended to as great a length, are distinctly shown to form part of the abdomen, while the corresponding parts in the male, the terminal segments, are developed into a claw- shaped prehensile organ. A similar modifica- tion of structure exists in all other insects. In some species one or more of these parts be- comes atrophied, or is developed to a greater extent than the others, and the result is that in some instances we find long, exsertile, and appa- rently new organs, while in others some parts, even of the annuli themselves, appear to be ab- sent. But the normal number is almost every where present, either simply as terminal plates of the abdomen, between which the proper ex- cretory portion of the organs of generation is concealed, or more highly developed, and form- ing a separate sheath for that structure. In the male insect (fig. 437) the organs con- sist of an external portion, the penis (h), or " organ of intromission," in which is inclosed the termination of the ductus ejaculatorius, which extends backwards, and is connected with the vesicular seminales (e) and vasa dej'e- rentia, which are connected with the epididymis and the proper testes («). These parts are found in a large number of insects, in some de- veloped to a great extent, but in others almost entirely atrophied. This is the order in which the parts are met with when passing from without inwards. The penis of the male, like the ovipositor of the female, assumes a variety of forms. It is usu- ally inclosed between two lateral plates, the ana- Male organs of generation of Athalia centifoliee. m ( Prize Essay.) j Fig. 437. logues of the sheath of the ovipositor, and which are derived from the terminal or penultimate segment of the body. With- in this isacorrugated soft membrane, the preputium, which is continuous with, and is reflected inwards from the inferior margin of the anal aperture, and sepa- rates the organs of generation from the alimentary canal. When the penis is retracted it is covered by this membrane, which is corrugated upon it (fig. 402, s). In Coleoptera, as in the Carabidie and Melolonthida, the penis is a long hor- ny tube, retractile within the abdomen on the under surface as far as the anterior segments. The strong horny co- vering of this organ is simply a consolidated state of parts of the tissues which in other instances are soft and flexible. It contains within it the excretory portion of the ejaculatory duct. In most of the Coleoptera, and in many other species, it has this strong hardened exterior, ne- cessary apparently for its employment by cer- tain species, in which there is little flexibility of the abdominal segments, as an organ of in- tromission. In Carabus monilis, as noticed also in C. clathratus by Burmeister, the hard- ened case of the penis is gently curved down- wards to facilitate its introduction into the vulva of the female. At its extremity on the under surface it is a little elongated, and it is termi- nated by a soft corrugated glandiform structure, which is perforated in its centre, and represents a glans penis, the perforation in its centre being the oritice of the excretory duct. In other Coleoptera the penis is also inclosed in a horny sheath, and presents a great variety of forms in different species. In many instances it is fur- nished at its extremity with short hooked spines, by means of which the male effectually retains his connexion with the female. The external sheath of the male organs, which incloses the penis, is analogous to that of the ovipositor of the female, and is employed when it is well developed to open the vulva of the female. In many species it is scarcely at all developed, being like the sheath of the ovipositor only a highly developed portion of the lateral plates of the terminal abdominal segments. The cir- cumstances above referred to will not allow us to describe in detail the forms of these organs of generation in many species, we shall there- fore content ourselves with a brief notice of some of those of the Hymenoptera (fig. 437). The general form of the penis in this Order is similar to that of Athalia, and consists of a INSECTA. 991 short valvular projectile organ, covered exter- nally by two pointed horny plates (i), clothed with soft hairs. Above these are two other irregular double-jointed plates (/), convex on their outer and concave on their inner surface, and surrounded at their base by a bony ring (/c). They are half corneous half membranous, and folded together like a closed fan, and are furnished at their posterior margin with horny hooks (t), which are used as organs of prehen- sion. Between these in the middle line are two elongated muscular parts (?n), which when applied together form a pointed structure, and inclose between them in its retracted state the proper intromittent organ (h). These perhaps assist to dilate the vulva of the female, like the plates above noticed in the Coleoptera. In many instances, as in Anthidium munkatum, the posterior margin of the last true abdominal segment is armed with spines that are curved downwards, and serve to retain the female, and this is also the case in the Chrusidida. In Anthophora retusa the horny penis formed of the last two segments of the larva has also two external plates developed into hooked prehen- sile organs, with which the insect grasps the abdomen of the female at the moment of actual connexion. In the Sphinx (fig.'iQV) and other Lepidoptera the appendages of the anal seg- ment appear to be analogous to the sheath of the ovipositor in the preceding orders. On each side of these parts at their inner surface are two horny plates, which form the lateral boundary of the male organs. Within these is a cloaca, in which the anal aperture terminates, and immediately beneath it are situated the male organs. These consist of an extensile bifid, ejaculatory organ included between two soft valvular parts. They form the virile organ. In the Sphinx the posterior margin of the dorsal plate of the terminal segment is armed with a slender curved hook, bifid at its apex, and bent downwards, like the hooks in the body of Hymenoptera, for retaining con- nexion with the female. Among the Diptera the Asilida have the male organ formed in a somewhat similar manner. The terminal seg- ment of the body forms a pair of broad horny plates, which inclose between them the double stiliform excretory canal. The ductus ejaculatorius passes backwards from the penis as a single canal, which either is exceedingly short, as in Athalia, (Jig. 437,/), or is a very long tube, forming many convolutions in its course, as in many of the Coleoptera. Into this canal open the vesicula seminules and the vasa deferentia. The vesicula seminules are usually long convoluted ccecal tubes, which assume a variety of forms, sometimes branched sometimes simple. They are two, and some- times four in number. In some species, as in Athalia (e), they are exceedingly short, and very much dilated, serving evidently as recep- tacles for the semen as it is secreted by the testes, and conveyed towards the ejaculatory duct by the vasa deferentia (d). These, like the seminal vessels, vary in number according to the number of the testes. When the whole of the testes are aggregated together, the vasa deferentia that proceed from them are united from each set of testes into a single tube on each side (b), but when the testes remain dis- tinct from each other, each deferential vessel passes at first separately from each testis for a short distance, and the whole are then collected together, and form on each side a single tube, which, after many convolutions, either is in- serted into the extremity of the seminal vessel, or is inserted along with it into the commence- ment of the ejaculatory duct. The length of the common deferential vessels is sometimes so great, and they are so much convoluted, as to be readily mistaken for testes, much larger than the proper testicles. This is the case in Athalia (d). The proper testes are usually several rounded glandular bodies, in some instances, as in Melotontha* and Lucanus, amounting to as many as six on each side, and in a few in- stances, as in Athalia, even to as many as thir- teen. In form they are sometimes rounded, and sometimes are elongated coeciform tubes. They are usually regarded as ccecal organs, but in some instances we have distinctly traced minute vessels connected with them, but whether these vessels passed by open mouths directly into the coeca, or whether distributed over their surface, is perhaps still a question; our impression cer- tainly is that they enter the testes. Besides these parts, there are in some instances struc- tures that resemble an epididymis, as in Hy- drous,\ but these are generally absent. These organs lie within the abdominal cavity, in general on each side of the alimentary canal, and sometimes above it, as in the instance of the Lepidoptera, in which the two separate testes of the larva (jig. 364, i) are united in the perfect insect into one mass, which is situ- ated immediately beneath the dorsal vessel (fig. 366, i). In each of these cases the con- nexion with the vessel, as formerly noticed, is distinctly traced. Besides these parts we ought also to notice some which are appendages of the organs similar to appendages found in the female, but the function of which is not dis- tinctly understood. In the female the organs of generation are more simple than in the male. Of these we have first to notice those external parts which form, as we have stated, either the long ex- tended ovipositor of the Gryllida:, the sheath of the sting of the bee (jig. 438, A, a,d), or the sheath or valves of the ovipositor of the Terebrantia (C, b). The condensed descrip- tion of these parts that has been given by Mr. WestwoodJ clearly explains their structure. He remarks that, " from the centre of the under side of the abdomen, near its extre- mity, arise two plates, each consisting of two joints, sometimes valvular and together forming a scabbard, sometimes more slender, and resembling palpi, and sometimes very long ; between these plates, as they exist in the bee (A, b), under the form of two flattened plates, with a pair of terminal lobes, arise two other pieces which are very slender, serrated * Straus, t Dufour. t Entomologist's Text Book, p. 375. 992 INSECTA. Fig. 438. ft A, lateral view of the sting of the Bee. ( Westwood. ) a, the sheath; b, terminal segment of the abdo- men ; c, the barbs or proper sting ; d, the chan- neled surface of the sheath of the sting in which the barbs are concealed. B, the poison-bag and vessels of the sting of the Anthophora retusa ^Newport) ; a. sheath of the sting ; 6, the dilated extremity of the poison duct ; c, d, the bag ; e, efferential vessel ; f, the secretory organs; g, their vessels. C, terminal segment of the abdomen of a saw-fly, Triclwsoma (Lyonet) ; a, dorsal end of the ter- minal segment ; b, sheath of ovipositor or terminal ventral arch ; c, d, the inner plates or saws, analo- gous to the barbs, c, of the sting of the bee. D, one of the double lancet-pointed saws of Athalia centifolice. at the tip in the bees (c) but much broader in the saw-flies (C, c, d) and transversely striated, forming the saws with which these insects are provided : moreover these two pieces are re- ceived in the bees into a canal (A, d), but in the saw-flies this gutter is broad, flattened, and divided into two separated parts, forming the backs of the two saws. In the Ichneumons these various parts are so slender that at the first sight they appear to consist but of a single piece : on more minutely examining the in- strument, however, it will be found that it consists of a scabbard, composed of two pieces, inclosing a fine hair-like bristle, which is, in fact, the exact analogue of the stinging part of the bee's sting, consisting of three pieces." This organ constitutes both a means of defence and also of depositing the eggs. There have been some doubts with regard to this fact in the bees, some having questioned whether the sting is at all employed in oviposition by these in- sects ; but a most careful and accurate ob- server, Dr. Bevan, distinctly states that the ova pass along the sting of the bee lo be de- posited, and this statement is confirmed by the fact that this is certainly the case in the analogous instrument of the saw-flies, as we our- selves have distinctly witnessed in Athalia ce.ntifoliaz. The analogy, therefore, of the sting with the ovipositor of the Gryllidaz, of the saw- flies, and other insects, is distinctly proved. In Athalia the ovipositor is a very interesting organ. It occupies the under surface of the seventh and eighth segment of the body, and is approximated to the posterior margin of the sixth, a part of the seventh having been re- moved. Four tendons for the insertion of muscles originate from the extremity of the two halves of the ovipositor. In the mem- brane that unites on the under surface the two halves of the ovipositor, is situated the vaginal orifice between the two saw-shaped organs (C, c, d, D). Each of these parts is composed of two plates applied together back to back, and which together form a pointed instrument resembling a lancet (D). The upper one of these plates (i) is furnished with small sharp- pointed teeth directed backwards, and the under one (/c) with fourteen long and slightly convex ones. With the point of this instru- ment the insect pierces the edges of the leaves of the turnip, separating the cuticle with its saw preparatory to depositing its egg, which is conveyed along its inner surface, which is slightly concave to allow of its safe transit along the plates. Posteriorly and external to these plates are the two sheaths of the ovipo- sitor (C, b) analogous to one portion of the ovipositor of the Gryllidce. In all those Hy- menoptera furnished with an ovipositor there is also an apparatus for secreting a peculiar fluid, and this apparatus is believed to be analogous to the appendages of the male organs above alluded to, the use of which is not well under- stood. In the female these parts consist of an excretory duct, and bag, or receptacle for the fluid, a convoluted efferential vessel, and proper secretory organs. In the wild bee, Anthophora retusa (B), at the base of the sheath (a) in which the two barbs of the sting (A, e) are concealed, is a smooth dilated space, into which the poison is first received at the base of the sting. The poison is conveyed to this space by the efferential duct (c) from an oval sac (d ), in which it is accumulated as secreted, and into which it is poured by a very large and much convoluted efferential vessel (e), which receives the fluid from two coeciform glandular organs (f), which unite as they enter the efferential vessel. These secretory organs receive at their apparently closed extremity each a minute vessel, which we have distinctly traced to some distance from them, but not to its termination. When the poison is ejected from the bag (d ) into the base of the sting, it passes along be- tween the two barbs, as in a little gutter, into the wound. Swammerdam delineated these parts in the honey-bee, but did not notice the vessels proceeding from the secretory organs. In another insect of the same class there are similar structures. Thus, in Athalia (Jig. 439), the bag (g) is oval, but the efferential vessel is entirely absent, the fluid being poured directly from the secretory vessels (/() into the bag with- out passing along any other tube. The vessel is INSECTA. 993 Fig. 439. Female organs of generation of Athalia centifoliae. ( Prize Essay.) also absent between the bag and the base of the ovipositor, so that the fluid is forced directly from the bag at the moment it is employed. There is a somewhat similar structure in the Hornet, although the vessel between the bag and sting is present as in the bee. Burmeister has suggested that the poison-gland may per- haps be an urinary organ, but the circum- stance of the fluid contained in it being em- ployed by the insect to inject into the cavity iji which it deposits its ova, seems opposed to this opinion, although that of its being em- ployed by the bee as a means of defence may be favourable to it. The nature of this fluid is distinctly acid, as remarked by Dr. Bevan in the honey-bee, and as found by ourselves in several instances. The vaginal aperture at the base of the ovipositor forms the external orifice of the common oviduct or proper laying tube (e). This in some instances is simply a di- lated orifice, the internal lining of which is .continuous with that of the internal part of the ovipositor. This common oviduct is either a simple, straight, uniform tube, or in some in- stances is a little dilated laterally into pouches, in which are received the lateral appendages of the male organ, as in Melolontha. At its termination the common oviduct divides into or rather receives two separate tubes (d ), one from each side, analogous to the eft'erential vessels of the male organs. On the upper surface of the common oviduct, there are appendages that vary in number from one to five. The chief of these, the spermatheca (f), alone exists in Athalia. It is into this sac that the fluid of the male is ejected during co- pulation. Audouin states that the male organ is projected into it. We have invariably found this vesicle, which is exceedingly large in Meloe, filled with white, opaque, seminal fluid after connexion with the male, previously to which time we have as invariably found this vesicle ^mpty. This appendage is simple in many ,of VOh, II. the Orthoptera as well as in Hymenoptera, but in some other species there are also additional vesicular appendages which have been de- scribed as secreting a glutinous fluid. In all in- stances these are attached to and pour their con- tents into the common oviduct, through which the eggs pass to be deposited. In the middle line, at the union of the oviducts, are situated the terminal ganglia of the nervous cord (10, 11), when the cord is extended to the posterior part of the abdomen. But when this is not the case, and the nerves simply radiate from the thorax into the abdomen, the terminal pair of nerves still pass in a corresponding direction over the union of the oviducts, thus always occupying a position between the organs of generation and the termination of the ali- mentary canal. From the two oviducts origi- nate the proper ovarial tubes. In Athalia cen- tifolia there are eighteen (a, b, c) attached to each oviduct, but in some other instances, as in Mel'ue, in which the upper part of the oviduct on each side is dilated into an im- mense bag resembling an uterus, they amount to some hundreds of exceedingly short tubes containing each but one or two ova. In Melo- lontha and Lucanus there are six on each side, but in some instances, as in Lixus, as shewn by Dufour,* there are only two on each side. These ovarial tubes gradually decrease in size from their base to their apex, and those from each side are collected together at their apices, and are said to terminate each in a dilated ccEcal extremity, but we must confess we have never yet traced this structure in any instance. Muller, as above stated, traced a connexion between the extremities and the ovarial tubes and the dorsal vessel in Phusma, and many other insects, as we have also done in several instances, but the nature of these connexions is disputed. They certainly appeared to us to be vascular, as supposed by Muller, and we have already stated the reasons that led us to the same opinion. We shall enter on a consideration of the function of the organs of generation when con- sidering this subject in Myriapoda. In concluding this lengthened article we have only further to remark that the tegumen- tary appendages consist of hair, scales, and spines. The first of these serves as a covering for the bodies of many species, more particu- larly the Hymenoptera, and is also found under the limbs in many Coleoptera. The scales are peculiar appendages and may be considered, according to many, as simply flat- tened hairs. They entirely cover the bodies of many species, as for instance the Lepidoptera. The curious forms and marking of these parts are sometimes exceedingly beautiful ; but the limits of our article will not allow of our en- tering at present on the consideration of them. The spines are found much on the wing of Hy- menoptera and are often mistaken for true hairs, between which and spines, and also between « these and scales, there is a difference of origin, * Annales des Sciences Naturelles, torn. vi. pi. 20. 3 T 994 INSECTIVORA. spines being usually developed directly from a trachea or part of a membrane in the immediate vicinity of a trachea. Bibliography.— In addition to the foot-notes attached to the article the following are some of the principal works on Insects : De Animalibus Insectis libri septem, A uctore Vlysse Aldrovandee, fol. Bonon. 1602. Experimenta circa Generationem Insecto- rum, Francisco Redi, Florence, 1668. De Bombyce, M. Malpighi, 1687? Historia Insectorum, Londini, 1710. Methodus Insectorum, seu Insecta in Metho- dum aliqualem digesta, Johannes Ray. Systema Naturae, 1735-1770, Carolus von Linnceus. Memoires pour servir a l'Histoire des Insectes, par Charles De Geer, 7 torn. 4to. Stockholme, 1752. Traite d'ln- sectologie, par Charles Bonnet, 8vo. Paris, 1748. Biblia Natura;, fol. by J. Swammerdam, translated by Thomas Flloyd, with Notes by J. Hill, London, 1758. Entomologia Carniolica, exhibens Insecta Carniolia? indigene, &c. 8vo. Joannis Antonii Scopoli. Vindobona;, 1763. Memoires pour servir a l'Histoire des Insectes, 6 torn. 4to. par Rene Antoine Erchhault de Reaumur. Traite Anatom. de la Chenille, 4to. par Pierre Lyonet, 1760. Spicilegia Zoologica, &c. a Petr. Sim. Pallas, M.D. 4to. Berlin, 1767-1780. Systema Entomologia;, &c. 8vo. Jo. Christ. Fabricii, Flensburgi et Lipsiae, 1775. Nova; species Insec- torum Centuris 1. Auctore Joanne Rionoldo Fostero, 8vo. Londini, 1771. Historia Naturalis Curculio- num Suecize, Auctore Gabriel Bonsdorf, 4to. Up- Bali;e, 1785. Entomologia Parisiensis, edente.A. F. Fourcroy, M.D. 2 torn. 12mo. Parisiis, 1785. Ex- position of English Insects, arranged according to the Linnean System, 4to. London, by John Harris, 1782. Entomologia Helvetique ou Catalogue des Insectes de la Suisse, ranges d'apres une nouvelle Methode, avec Descriptions et Figures, Claiville, Zurich, 1798. Tableau elementaire de l'Histoire Naturelle des Animaux, par G. Cuvier, 1797. Natural History of British Insects, by E. Donovan, 16 vol. 8vo. London. 1792-1818. De antennis In- sectorum, 8vo. 1799, Lehmann. Vivarium Naturae, the Naturalist Miscellany, by G. Shaw. Lepidop- tera Britannia;, Auctore A. H. Haworth, 8vo. Lon- dini, 1803. Monographia apum Anglia:, by W. Kirhy, M.A. 2 vol. 8vo. Ipswich, 1802. Introduc- tion to Entomology, by William Kirby, M.A. and William Spence, vol. iv. 1816-1828. Historia Nat. des Animaux sans Vertebres, &c. par M. le Cheva- lier de Lamarck, 5 torn. 8vo. Paris. Extrait du Cours de Zoologie, &c. par M. de Lamarck, 1812, 8vo. Elements of Natural History, 2 vol. 8vo. Iiondon and Edinburgh, 1802, by Stewart. Histoire Naturelle des Crustaces et des Insectes, par P. A. Latreille. British Entomology, by John Curtis, F.L.S. Histoire abregee des Insectes, Paris, 1764, 2 torn. 4to. by Geoffroy. Illustrations of British Entomology, by James Francis Stephens, F.L.S. Horae Entomologia;, by W. J, Macleay. Entomologia Britannica, 1 vol. 8vo. 1802, by Tho- mas Marsham. Considerations Generates sur l'Ana- tomie comparee des Animaux Articules.par Hercules Straus Durckheim, 4to. Paris, 1828. Modern Clas- sification of Insects, by J. 0. Westwood, F.L.S. (G. Newport.) INSECTIVORA, (Insecta, voro,) a group of mammiferous animals, considered by some au- thors as a distinct order ; by others, and parti- cularly by Cuvier, as a family only of the great carnivorous order, named by that great natura- list Carnassiers. The peculiarities of struc- ture by which the Insectivora are characterized appear to me to be equally important with those which have led me already to treat of the Chei- roptera as an ordinal group, and I shall there- fore consider them in that point of view. They consist of four very distinct groups, the relations of which are not very clearly fixed. I have ventured to consider them as four families, viz. : — Talpid«, typified by the mole, Talpa. Erinacead*, by the hedgehog, Erinaceus. Soricidje, by the Shrews, Sorex. Tupaiam:, by the genus Tupaia. Such at least appears to me, in the present state of our knowledge, to be a near approach to the natural groups of which the order i9 composed. In the Talpida I include the ge- nera Talpa, Condytura, and Chrysochloris ; in the Soricida, the genera Sorex, (with the sub- genera, so called, into which it has lately been subdivided,) Mygale and Scalops, the latter genus being clearly osculant between the Soricida and the Talpida ; in the Erinaceadte, the genera Erinaceus, Echinops, and Centenes ; and m the Tupaiada, the single genus Tupaia, or Cladobates, as it is named by Fred. Cuvier. It will at once be seen, by reference to this enumeration of the types of form which occur in this order, that animals, differing greatly in their general structure and habits, are included in it. But it will also be found that they all agree in the general character of their teeth, which are in all instances furnished with ele- vated and pointed tubercles, for the purpose of breaking down the hard and polished elytra of coleopterous insects, upon which most of them in a greater or less degree subsist. This cha- racter has already been exhibited in the insecti- vorous group of the Cheiroptera, which we have considered as leading towards the present order ; and even in the lower forms of the Quadru- mana a similar tendency is evident, as in the Maki, the Loris, and others. They agree, also, in being for the most part nocturnal animals, and, with some exceptions, in living under ground, or at least in exhibiting a tendency to such a mode of life; and all those which in- habit the colder countries pass the winter in a state of torpidity. They all possess clavicles ; their limbs are generally short, and they are plantigrade. They have ventral mamms, the stomach is perfectly simple, and they are desti- tute of a ccecum. The different families which I have named are as well characterized by their habits as by their external form, and their more intimate structure. The Talpida, the teeth of which are shewn in the genus Talpa (fig. 441,) and Chry- sochloris (fig. 450), which are pre-eminently subterranean, are distinguished by their extra- ordinary habits of forming long and complicated burrows underground, passing their whole lives in a subterranean retreat, in which they are born, feed, breed, hibernate, and die ; and which re- treat, in the case of the common mole, is formed with the utmost art, and a beautifully complica- ted construction. The Soricidm (fig. 449) are a sort of carnivorous mice; and although they do not actually burrow, retreat during the winter, and in their ordinary repose, into holes, feed- ing, however, on the surface or in the water, several of them being partially aquatic, diving with facility after aquatic insects, and remain- ing without difficulty a long time under water. In both these families there is a peculiar cha- INSECTIVORA. 995 raeter in the structure of the hair, which favours the habits I have mentioned, and which will be presently described. In the Erinaceada (see fig. 451) we still have hibernating animals, but these, instead of burrowing or descending into deep excavations, conceal themselves only under leaves, or in any superficial hollow, and live upon food which they either find upon the sur- face or dig out of the ground with their hard moveable muzzle ; the character of their integu- ment is very peculiar, the hair being modified into spines of a greateror less degree of firmness, and the animals being mostly capable of rolling themselves into a ball, and thus presenting a panoply of sharp spines to their enemies. The last-named group, which I have named Tupai- adJ. o o Toti cerv B J M u Erinaceus Europaius (Hedge- 15 6 3 12 43 Centenes ecaudatus (Tenrec) . 15 5 3 10 40 1-1 7 3? 9 40 13 7 2 25 54 Sorex araneus (Shrew) .... 14 6 5? 14 46 S. fodiens (Water-shrew) . . 13 6 5 17 48 ChrysochlorisCapensis (Cape 19 3 5 5 39 Talpa Europ&a (common mole) 13 6 6 11 43 T. caca (blind mole) 14 .r. 5 1 1 42 Condytura cristata (radiated mole 13 6 5 17 48 Scalops (mole-shrew) 12 7 (3 10 42 It is worthy of remark, in taking a compara- tive glance at this list, that the length of the tail in the different species is in exact accord- ance with their habits, as far at least as we are acquainted with them. Thus, in Tupaia, we observe a tail as long as that of a squirrel, and obviously for the same object, that of balanc- ing the animal when taking leaps from one branch to another ; and in the Water-shrew the tail is lengthened to assist in swimming, for which purpose it is also fringed on each side with stiff hairs. Of the habits of the Condy- tura* we know little, and of that little nothing which accounts for the considerable proportion of the tail. Of the form of the different vertebra? in the various groups of the Insectivora, little need be said, as there are few circumstances con- nected with these bones which bear materially upon any physiological point. It may be ob- served, however, that in the Talpida and the Soricida the cervical vertebrae form large rings, have strong transverse processes, and, except- ing the second, do not possess any spinous processes. In the Erinuceadte, and particu- larly in the Tenrec (Centenes ) the transverse processes are particularly large, and the rings smaller than in the former families. The spi- nous processes are also wanting in the dorsal vertebra? of the mole. The sternum offers some peculiarities worthy of notice. In the mole the first ster- nal bone is very large and compressed. To its anterior pointed extremity the thick short clavicles are attached, and further back to the same bone, the first rib is articulated ; to the second bone is fixed the second rib, and there succeed to these three elongated bones of the ordinary form, to each of which two pairs of ribs are articulated ; then a small bone, to which one pair of ribs is fixed, and then the xiphoid bone, which is long and narrow. In the Chrysochloris the first bone of the sternum is equally compressed but less elevated ; and the anterior half is furnished on the up- per part with two small aliform processes, which are concave, and support the first two ribs, which are extremely broad; the long slender clavicles are attached at its anterior point; and then follow seven other oblong pieces, and an elongated xiphoid bone, which bears at its posterior extremity a semilunar car- tilaginous dilatation. The ribs in the mole and its congeners are nearly all of the same length, giving that pe- culiar cylindrical form to the body which cha- racterises these animals, and which is so essen- tial to their habits ; and in the Chrysochloris the first rib is very much broader than the others. But it is in the bones constituting the anterior extremities, that the most remarkable and in- teresting peculiarities exist in some of the families of this group. In the mole especially, the anterior extremity (fig. 442) exhibits one of the most extraordinary modifications to be found in the whole of the Mammifera. The clavicle is fully developed in the whole of the Insec- tivora. In the mole (b) it offers the most * From the name condytura, given to this genus by Illiger, it might be inferred that the tail is furnished with knotty tuberosities ; this, however, is only seen in dried specimens, which doubtless furnished to Illiger the characters of the genus, and suggested its name. INSECTIVORA. 997 Fig. 442 abnormal deviation from the usual construc- tion. It is extremely short and broad, forming in fact nearly a square ; about the middle of its anterior margin a strong process rises, which gives origin to the subclavian muscle, which in this animal is greatly developed. It is articu- lated, as usual, with the sternum by its interior extremity, which may here be more properly called its interior margin ; but by its external margin it is connected moveably with the head of the humerus, which connection is rendered more solid towards the anterior part by a strong ligament. Its connexion with the acromion of the scapula is by a ligament merely, which extends from the acromion to the posterior and outer angle of the clavicles. In Condytura and even in Scalops the construction of this bone is on a similar type; but in Clirysochloris it is long and slender as in the other Tnsectivora. The scapula (a) in the mole is no less singu- larly formed than the bone just. described. It is elongated to an extraordinary degree, being not less than six times as long as it is broad at the broadest part, which is at the superior extremity. Towards the middle it is contracted and almost cylindrical ; and the spine, which runs nearly the whole length of the bone, is at this part almost effaced. The acromion, as before ob- served, has only a ligamentous connexion with the clavicle. In Condytura and Scalops the construction of this bone is somewhat similar, and in Chrysochloris it is also of considerable length. The humerus in the mole (Jigs. 442, c, 443) is of so extraordinary a form, that were it examined alone, isolated from its natural con- nexions, it would be impossible to detect its true character It is of a square form, extremely broad at the superior part, where it presents two articular surfaces; the an- terior is very broad, slightly convex ; the posterior and internal is narrow, but more convex than the former ; by the first it is articulated to the clavicle, and by the latter to the scapula. Between the former, which may be considered as appertaining to the greater tuberosity of the bone, and the head, is a deep fossa. The body of the bone is short, thick, and very broad, and is curved upwards, so that its articulation with the forearm is placed actually higher than the shoulder, and the palm of the hand is consequently turned outwards. In Chrysochloris the form of this bone is not less remarkable. It is somewhat longer than that of the mole ; its articulation with the forearm constitutes half a sphere ; and the inner condyle is so elongated and inclined downwards, that the whole bone forms an arch of which the convexity is turned outwards. This condyle is articulated with a bone, which must be considered as a most extraordinary modification of the ospisiforme, which is as long as the radius, so that in fact the forearm may be said to be composed of three bones. The bones of the forearm (Jig. 442, d,e) in the extraordinary animal which offers so many de- viations from typical structure, the mole, are no less remarkable than those of the shoulder. The ulna is very broad and much flattened ; its superior extremity is enlarged transversely, the anterior surface concave, the posterior convex. The radius is separated by a considerable in- terval from the ulna throughout their length, and the two bones are only united at the upper extremity by a capsular ligament. But the articular surfaces of the two bones are flat, and the head of the radius is prolonged into a hook- like process, forming a sort of radial olecranon, so that rotation is impossible. The carpal bones (Jig.444) consist of two series of five in each, and an additional bone of a very peculiar construc- tion. This is a large sickle-shaped or falciform bone, having the convex margin outwards ; it extends from the carpal extremity of the radius to the first metacarpal bone. It is this bone which gives the great breadth to the hand, which is so important to this animal in its peculiar mode of life. The phalanges of the fingers are very short, and covered by the integument in such a manner as to appear to belong to the meta- Fig. 443. Fig. 444. 998 INSECTIVORA. carpal portion of the hand ; and it is only the long sharp nails which extend beyond the skin, and are externally visible. The position then of the anterior extremity of the animal is this : the humerus is so placed that the inferior or distal extremity is the most raised, so that the fore-arm is kept in a state between pronation and supination, the elbow raised, the radius and the thumb placed down- wards, and the palm of the hand directed out- wards. When- to this we add the peculiar flexion of the last phalanx of the fingers with the enormous nails, we have a fossorial struc- ture not equalled by any other in the whole of the vertebrated animals, and only imitated by the no less remarkable anomaly amongst insects, the Gryllotalpa or mole-cricket. In Chrysochloris the third and fourth fingers are united by one large powerful nail, and are developed to an extraordinary size (fig. 445), Fig. 445. the fifth finger being reduced to a minute ru- diment; and the carpal bones are placed in an abrupt curve, so that the outer side of the fifth finger approaches the first. The os pisiforme as- sumes also a peculiar development, being very much elongated, rises in the direction of the forearm, and is actually articulated with the internal condyle of the humerus. The pelvis in the Talpida and Soricidee is extremely long. The ilia are narrow and pointed at the anterior part. In the last-named family, the pubis and the ischium are especially long and narrow. In Chrysochloris, on the contrary, the ischium is very broad. The femur offers but few and unimportant particularities amongst the Insectivora, unless it be that there is in the mole and Chrysochloris a sort of third trochanter; a process which is also found in some of the lower Quadrumana, and in some other of the Mammifera. The fibula is united to the tibia for nearly the inferior third of their length, in the Talpida, the Soricida, and the Erinaceada. In the mole this union is to a greater extent than perhaps in any other animal of the Mammiferous class. The hinder feet in the whole of this order are plantigrade. In the mole, as Daubenton and Meckel have observed, there is an addi- tional tarsal bone, to those which are ordinarily found. It is of considerable size, and seems to answer to the falciform bone of the anterior extremities already described. It is of an uniform shape, of considerable size, and is arti- culated between the scaphoid and the first cuneiform bone, and extends forwards along the first metatarsal. II. Muscles. — The extraordinary develope- ment of the bones of the anterior extremity in the mole, will, of course, be associated with a no less remarkable structure in the muscles of the same part ; and the known habits of the animal will account equally for the necessity of such a structure in both. I give a figure of the muscles of the anterior extremity and of the anterior part of the trunk from Cams. (Fig. 446.) Fig. 446. INSECTIVORA. 999 The cervical portion of the serratus magnus is simple, excessively thick and swelling, and is attached only to the posterior vertebra?. The trapezius consists only of two bundles of fleshy fibres, which arise from the lumbar ver- tebra, and are inserted into the posterior ex- tremities of the long and narrow scapula ; and as these fasciculi are nearly parallel, their action would be rather to separate than to ap- proximate the posterior parts of these bones, were it not for a strong transverse ligament which holds them together. Their application consists in moving the anterior part of the body upwards. The scapular attachments of the rhomboideus are principally to this transverse ligament of the two scapulae, and as it is in- serted into a sort of ossified modification of a cervical ligament, its office consists in raising the head with great force. The levator scapula is wanting ; its existence would be obviously useless. The pectorulis minor is very slender ; it is attached to the anterior parts of the first ribs, and to the ligament, already mentioned, which joins the clavicle to the scapula. There are also two muscles arising from the anterior part of the sternum, and inserted into the large head of the clavicles. The most important muscles of the humerus are the pectorulis major, the latissimus dorsi, and the teres major, all of which are of great size ; and it is by means of these muscles that the astonishing efforts of the animal are made in excavating his passages, and throwing the earth behind him. The pectorulis major is of extraordinary thickness. It is formed of six portions, which are all of them inserted into the broad quadrate portion of the humerus. Four of these portions arise from the sternum, the fifth from the clavicle ; and the sixth passes across transversely from one arm to the other. The latissimus dorsi is also of considerable size, and is inserted into the posterior surface of the quadrate portion of the humerus. The teres major, which is of enormous thickness, is in- serted near the former muscle. The other muscles of the anterior extremity do not require particular description. There is one peculiarity in the muscular sys- tem which deserves special notice; it is the enormous developement of the punniculus cur- nosus in the hedgehog, by which it is enabled to roll itself up in a ball with such astonishing force as to afford with its spiny covering a complete protection against its most powerful antagonists. I proceed to describe this ap- paratus and its uses. As this muscular apparatus has no attach- ment but to the skin, it changes its position with every movement of the integument ; and it is therefore necessary to consider it under the various relations which it assumes in the different positions of the animal. Considering it then, in the first place, as rolled up in a ball (fig. 447), either for defence or during repose, Fig. 447. the whole body is enveloped beneath the skin by a strong sac or covering, consisting of a mass of fleshy and concentric muscular fibres, of an oval form. All these fibres are attached intimately to the skin, and even to the base of the spines with which it is every where furnished, so that it is even difficult to detach the fibres in dissection. The thickest part of this fleshy sac is at the lower margin or mouth of the sac, at which part it forms a sort of sphincter, com- posed of orbicular muscular fibres. On the other hand, when the hedge-hog is unrolled, and at its full length (fig. 448), the muscle in question totally changes its figure and relations. The muscle now lies over the back, forming an oval covering, the middle of which is very thin, Fig. 448. 1000 INSECTIVORA. and the circumference exceedingly thick and somewhat raised. To different portions of this circumference of the muscular covering are attached several accessory muscles. Anteriorly there are two pairs ; one arising from the me- dian line and inserted into the nasal bone ; the other, more external, apparently confounded at its origin with the external orbicular fibres, is inserted into the side of the nose and incisive bones. Posteriorly a pair of broad muscles, of a pyramidal form, arise from the posterior part of the fleshy circumference, and are in* serted into the side of the tail towards the ex- tremity. On the ventral aspect there are also several portions of muscle, belonging to the same ap- paratus. There is one beneath the throat, aris- ing from the anterior part of the thorax, under the skin, and is inserted about the lateral parts of the head near the ears. Another arises from the median line of the sternum, and passes obliquely forwards over the shoulders, in front of them, to join the margin of the great or- bicular muscle before described. There is another ventral portion which has a very ex- tended connexion. It is attached around the anus, to the lateral parts of the tail and neigh- bouring parts, extends over the whole surface of the abdomen, and then divides into two portions; one internal, and larger than the other, passes under the axilla, and is inserted into the superior and interior part of the humerus ; the other, external, passes laterally upwards, to be inserted into the margin of the great or- bicular muscle near the neck. The muscles hitherto described lie superficially ; but there are others which are seated underneath the great muscle of the back. One arises from the side of the head, being attached to the meatus auditorius on each side, and loses itself in the anterior point of the orbicular muscle. There is also a thin layer of fibres lying beneath the great muscle, of which the anterior are attached to the superior interior portion of the humerus, and the posterior to the third ventral muscle already mentioned. We have here a very extensive and a very powerful apparatus, and it now becomes ne- cessary to consider its application. When the hedgehog is rolled up in a ball, it is com- pletely enveloped, as regards all the upper and lateral parts of the body, in the great orbicular muscle. When once brought into this position the simple contraction of the thick circum- ference of the muscle, which forms a true sphincter, is sufficient to retain it. If the ani- mal unrolls itself, the disc of the great muscle contracts whilst the circumference is relaxed, allowing the exit of the feet and the uncover- ing of the belly and sides : then the whole muscle contracts together, and lies in a mass on the back. By this universal contraction, the necessary muscles become stretched, and in a condition to perform their several offices; by the contraction of the anterior ones the head, and by that of the posterior the tail, is raised, whilst those which lie beneath raise the head and neck together, and the animal is now ready for progression. On the other hand, on the apprehension of danger, or when' reposing, it rolls itself into a ball by the following pro- cess. The orbicular muscle relaxes, and the muscles extending from it to the head and to the tail extend it in those directions, whilst the deap-seated transverse muscles which are at- tached to the external lateral portions, and lie on the belly, bring this part of the circum- ference downwards. At the same time the head is brought downwards towards the breast by the ordinary flexion of the head, and by the cutaneous muscles of the neck already de- scribed; the tail and the hinder legs are brought forwards under the belly, and the flexors of the limbs contract. The great orbicular muscle passes downwards over the sides, then contracts at the circumference, and forms a sort of sac or purse, enveloping the whole body and limbs. III. Digestive organs. — It is, of course, in the structure of the digestive organs, and par- ticularly in that of the teeth, that we find the distinguishing characters of the whole order ; yet so nearly do these organs in the Insecti- vora approximate to those in the insectivorous division of the Cheiroptera, that it would not have been possible to separate the two groups, had there been no other important points of distinction. From the insectivorous Quadru- mana they are distinguished by the planti- grade character of the posterior extremities; from the bats by the whole structure of the limbs, and from all the true Carnivora by the tuberculated teeth. There is no inconsiderable difficulty in as- signing the various anterior teeth in the Insec- tivora to their proper classes. In most of the genera, according to the statement of both the Cuviers and others, there are no canine teeth, and the false molares are very numerous ; but it is in many cases doubtful whether the an- terior false molares, as they are termed by these anatomists, be not theoretically canines modified in their form. On this point, how- ever, there is no possibility of coming to a satisfactory conclusion, as every one will at last form his own opinion on each case; I shall therefore follow the arrangement of Frederic Cuvier as the most generally known, and, upon the whole, by far the best authority on the teeth of the Mammifera. The incisive teeth vary greatly in the dif- ferent genera. In Mi/gale, in Scalops, and in Condytura, there is in the upper jaw but a single incisor on each side, which is very strong and of a triangular form. In the first of these genera it is somewhat curved downwards and backwards, and slightly resembles that of some Rodentia. In Sorex (JigA49) it is also single, very strong, curved, and similar to the canine tooth in the Carnivora, but furnished with a strong tooth-like process posteriorly, appearing almost like a distinct tooth. In Talpa (jig. 441) there are three superior incisores on each side, which are small with cutting edges, like those of the Carnivora. In Chrysockloris (fig. 450), the single superior incisor is curved, convergent, obliquely trun- cate and pointed; and in Erinaceus (fig. 451) there are three pairs, of which the first is large, Fig. 4-49. Sorex 1 INSECTIVORA. 100 L Fig. 451. Erinaceus. Fig. 450. Chrysochloris. Fig. 452. Tupaia. obtuse, and strong, separated by a considerable interval from its fellow, and convergent with it. The others are small and resemble false molares. In Tupaia (fig. 452) these teeth are two on each side, distant from each other, and from the first false molar. The inferior incisores also vary greatly in their form and number. In Scalops there are two, the first small, the second larger and resembling in form a canine tooth. In Condytura there are two, rounded in front, flattened behind. In Talpa there are four similar to those of the upper jaw, and in Sorex there is one only of a very pecu- liar form : it is very long from the anterior to the posterior part, somewhat hooked, pointed, and, in_ some species, the edge is notched or trifid. There are no true canines, according to the opinion of Frederick Cuvier, in any of these animals, excepting Condytura, Talpa, (in which they exist in the upper jaw only) Centenes, and Tupaia. The first tooth be- yond the incisores, considered by Fred. Cuvier as the first false molar in the lower jaw in the mole, is by Baron Cuvier termed the canine. In Centenes these teeth are of the normal form ; and in fact the general arrrangement of the teeth in this genus indicates a marked approach towards the Carnivora. In Condytura the su- perior canine is strong and large ; the inferior merely rudimentary. The molares, as in the other Zoophaga, are divided into false and true. Those of the 1002 INSECTIVORA. former class are very numerous and of very various form in the different genera, and the great diversity of number in the molar teeth depends in most cases upon these, the true molares being but three on each side both above and below in all the genera, excepting in Chrysochloris, in which they are f:§, in Eri- naceus, in which they are and in Centenes In Chrysochloris the true molares are very curiously and beautifully formed : they are much compressed from before backwards, of a three-sided form, each of the angles ter- minating in a sharp elevated point ; thus, in those of the upper jaw, there are two situated externally and one internally, and in the lower jaw one externally and two internally. The whole of the true molares, in all the Insecti- vora, are formed of three-sided prisms, either single or double, and surmounted by acute tubercles. The salivary glands are generally much de- veloped in the Insectivora. In the hedgehog the parotids are larger than the submaxillary ; the sublingual are placed in two rows, of which the larger is situate nearest to the lower jaw. In the mole these glands are very large ; the parotids are of an oblong shape, and the maxillary are formed of several rounded and detached lobes. In Sorex the maxillary glands are of larger size than the parotids, and the latter are situated very low to accommodate the oblique direction of the auditory canal. The form of the stomach in this Order of animals is perfectly simple, and does not greatly vary in the different genera. It is situated transversely with regard to the axis of the body, is somewhat elongated, and the two orifices are distant from each other, as in many of the Carnivore, and in the insectivorous bats. The cardiac pouch is generally distinct and rounded; the pyloric extremity, on the con- trary, is conical and perfectly even. In Erina- ceus the cardiac point is considerable, the en- trance to the oesophagus being at no great dis- tance from the pylorus ; and the internal coat forms numerous ruga and folds. This form of the stomach and the existence of plicae must be considered as indicating an aberration from the insectivorous type, and a certain degree of ap- titude for the digestion of vegetable matters, and we find accordingly that this, with a slight exception or two, is the only family of the Insectivora which can exist upon any but the most exclusive animal aliment. The mole, the Chrysochloris, and all their congeners, are in this latter case; but the hedgehog, as is well known, will readily eat various vegetable sub- stances, and often digs under the common plantain for the purpose of obtaining the roots, of which it appears to be very fond. The sto- mach varies a little in its form in the different genera of the Soricida. In the great shrew of India it is transverse, the pyloric portion coni- cal, of moderate dimensions, the cardiac pouch small and the two orifices distant; a form which indicates an exclusive aptitude for insect food; but it would appear that the water-shrews ( Hydrosorex ) must occasionally have recourse to some kind of vegetable diet, as the pyloric portion is so much elongated as to resemble in some degree that of the Pteropida or fruit- eating Cheiroptera, exhibited in Jig. 287, vol. i. p. 600. In the mole the oesophagus enters at about the middle of its anterior margin, and the lesser curvature is nearly straight to the pylorus. The membranes are extremely deli- cate and almost transparent. The form is es- sentially similar in Chrysochloris and in Con- dytura. The stomach of Tupaia, according to the Baron Cuvier, is of a globular form. The intestinal canal is upon the whole re- markably short in the Insectivora. There are some exceptions to this rule, but the only one bearing upon a difference of aliment is that of the hedgehog, which, as has been before ob- served, lives partially upon vegetable matters. In this animal it is, with regard to the length of the body, as 6.6 to 1 . In Talpa and Centenes this proportion is even exceeded, but it is com- pensated for by the extreme narrowness of the canal ; the diameter of which is to its length, in the mole, as 1 to 82 ; whilst in the hedge- hog it is as 1 to 58. In Sorex its length is to its diameter only as about 3 to 1, or a little more. There is no ccecum known to exist in any of the Insectivora. Cuvier queries whe- ther Tupaia be not an exception, but this we have at present no means of ascertaining. The liver is in general fully developed in all its parts ; there are the principal lobe, to which the gall-bladder is attached, with a notch answering to the suspensory ligament, a right and a left lobe, and two smaller lobes or lo- buli, a right and a left. The whole of these parts are generally found, but varying without any known law, or any ascertained relation to functional peculiarity. In the hedgehog and in the mole the left lobule is composed of two portions, a cardiac and a pyloric, as in the Rodentia. In Tupaia, according to the state- ment of Cuvier, the three portions into which the liver is divided belong to the principal lobe; there is no right or left lobe, and the right lo- bule is also wanting. The gall-bladder is for the most part of considerable size. In the hedgehog its fundus appears beyond the free margin of the liver, and is supported by a process of falciform ligament. In the Tenrec, on the contrary, it is as it were incrusted by the substance of the right portion of the prin- cipal lobe. IV. Nervous system. — The form and propor- tions of the brain in some of the Insectivora ex- hibit a degree of developement not materially superior to that of the higher Carnivora; whilst others, and especially the mole, have the same higher proportion which are found in the Chei- roptera : thus in the hedgehog the volume of the brain is to that of the body as 1 to 168 ; whilst in the mole it is as 1 to 36. The pro- portion of the cerebellum to the cerebrum in the latter animal, however, indicates a consi- derable developement of the sexual functions, being as 1 to 4£. Supposing the theories of many modern physiologists to be correct, this fact is in perfect accordance with the neces- sities of the animal, whose means of obtaining access to the opposite sex are extremely diffi- INSECTIVORA. 1003 cult, and require intense ardour and, perseve- rance to effect this object. The most remarkable and interesting pecu- liarities which are to be met. with in the struc- ture of any of the Mammalia are to be found in the eye of the mole, and doubtless of the nearly allied forms of Chrysochloris and the other subterranean species. In these, in order to meet the requirements of their habits, the organ of sight is reduced to a mere rudiment, whilst those of hearing and of smell are deve- loped to an extraordinary degree; and the theory of the balance of organs can scarcely boast of a stronger support in the whole range of animal organization than in this instance. The question whether the mole possesses vi- sion has been long and often debated. With- out entering into an unnecessary examination of all that has been said on both sides of the question, it may be well to observe that the principal argument which has been urged on the negative is derived from the absence of an optic nerve. That this animal, at least our common species, does possess the faculty of vision to a certain degree cannot, however, be disproved, whatever may be the means by which the sense is communicated, that is to say, whatever the nerve may be which supplies the place of the true optic nerve ; and the ex- periments of Henri le Court and Geoffroi St. Hilaire* would well nigh go to prove the affirmative of the proposition. It has been urged then that an optic nerve is absolutely necessary to the existence of vision ; and that, therefore, either the mole has a true optic nerve, or that it does not possess vision. There have indeed been three classes of observers on this point ; those who maintain that the mole sees, and that it possesses an optic nerve ; those who contend that it is blind, and possesses no such nerve ; and others have ventured to agree with the former as to its power of vision, and with the latter in denying the existence of the optic nerve. The eye of the mole is extremely small, but differs not materially in its structure from that of other animals. The pupil is elliptic and vertical; the cornea even more convex than that of birds; there is a sclerotic and a true choroid. The crystalline lens is perfect, and much more convex than in most of the Mammalia ; and the eye-ball, emptied of its contents, exhibits at the base a lining of a whitish colour. " In an injected subject," says Geoffroi, " the cen- tral artery of the retina was distinctly seen." Whether there be or not a true retina will be variously solved according to the views of dif- ferent physiologists. If the nerve, whatever it may be, which takes here the place of the optic nerve, be really the seat of the sense of vision, there seems to be no objection to con- sider its expansion, upon which the pictures of objects are impressed, as a retina ; giving the name rather to the physiological than to the anatomical character of the part ; but be this as it may, from the posterior part of this minute * Geoff. St. Hilaire, C'ours d'Hist. Nat. des Mam. lev. 16. eye there passes a distinct branch of a nerve. Perhaps, after all, the name and analogy of this nerve will be viewed differently according to the general views of organic developement entertained by different physiologists. Geoffroy considers it as the optic nerve, notwithstanding it has no connexion with that part of the brain which in all other cases is in immediate com- munication with it; and he founds this opinion upon the theory that all organs are developed from without. His words are as follow: — " Qu'est ce que ce nerf ? La monstruosite et la nouvelle theorie sur le point de depart des developpemens organiques assure ma marche : appuye sur ces deux fanaux, aujourd'hui heu- reusement importes dans l'histoire encore si obscure des premieres formations je ne doute pas que ce ne soit le nerf optique. C'est ce nerf, parceque cet appareil, qui est au complet comme globe oculaire, a du se former de toutes ses dependances jusqu'a l'empechement qui en arrete le cours. Cette determination ne sauroit etre douteuse pour qui reconnait que les or- ganes naissent a la circonference de I'etre, d'ou ils envoient leurs rameaux s'embrancher au plus pres dans le centre.* Amongst those who assert that the mole pos- sesses a true optic nerve is Miiller. His state- ment is so brief, and, it may be said, so unsa- tisfactory, that it can scarcely be considered as sufficient to outweigh the carefully formed opi- nion of many who differ from him. His state- ment, as given in Dr. Baly's translation of his admirable book, is as follows: — " Some ani- mals, though provided with eyes — for instance, the mole and the proteus anguinus — have been said to want the optic nerves; the sense of vision being then placed in the ophthalmic branch of the fifth nerve. This statement has arisen, in the case of the mole, from inaccuracy in the anatomical examination; and the same is the case probably in the Proteus. The mole has an uncommonly small optic nerve, as Dr. Henle has shewn me."f On the other hand, Serres, Gall, Desmoulins, and others have agreed in delating that there is no nerve passing- from the optic lobes to the eye ; and Dr. Todd has recently verified this statement, and traced the nerve which does supply this organ, which he finds to be the ophthalmic branch of the fifth pair. I give an enlarged view of a dissec- tion of this nerve, drawn by Mr. Bowman. ( Fig. 453.) a is the fifth nerve within the cranium, b the Gasserian ganglion, c the inferior maxillary nerve, d the ophthalmic nerve going to the eye (e,) f the superior maxillary nerve, g branch of the ophthalmic, supplying the side of the nose. Dr. Todd in a letter to me says, " I have been lately looking at the point about the optic nerve in the mole. I can see an optic commis- sure, but no optic nerve beyond it, and I can very distinctly trace a branch [the ophthalmic] of the fifth to the eye. I carefully searched to see if a second nerve were bound up in the cellular sheath with it, but could find none. * Cours d'Hist. Nat. des Mammif. 16 If 9. p. 27. t Miiller's Phys. by Baly, p. 767. 1004 INSECTIVORA. The chiasma is very distinct, without a trace of a nerve proceeding from it." Fig. 453. The organ of hearing in the mole is so con- structed as to afford the greatest possible deli- cacy and acuteness of this important sense, and thus to counterbalance the deficiency in that of sight. It would indeed appear that the mass of compact bone constituting the petrous por- tion of the temporal, which surrounds the laby- rinth in most of the Mammalia, must more or less diminish the powers of hearing, for we find it deficient in many animals, which from their habits require this sense to be in the greatest perfection. Thus, in the mole, the semicircular canals are free and visible within the cranium, without any preparation ; and the parietes of the cochlea itself are almost as cellular and loose as we find in birds. The ear of the mole possesses no concha ; it is small in the shrews; and in the water-shrews (Hydfosorex ) the external meatus is closed at the will of the animal by means of the anti- tragus; a provision obviously essential to its aquatic habits. When it is considered that the sense of vision is only available on the rare occasions of the appearance of the mole on the surface, and then only for very limited objects, and that all its intimations of danger, and its only guide to the opposite sex, are by means of the sense of hearing, the necessity for this extraordinary deve- lopement of that sense at the expense of that of sight becomes obvious. And as, from the nature and situation of its food and its means of pro- curing it, the sense of smell is equally neces- sary for effecting this object, we find that the olfactory organ is also of considerable volume. The structure of the nose itself is highly curious and admirably suited to the habits of the ani- mal. The cartilages of the nose are elongated into a tube or trunk, which extends far beyond the osseous basis, and is supported by a very delicate moveable bone, which is represented in the figure of the cranium of the mole at jig. 441. It is furnished with a muscular appa- ratus of considerable complexity (seefg. 446), consisting of no less than four pairs of muscles, which arise from above the ears, and passing forwards are inserted by separate tendons into the circumference of the extremity of the carti- laginous snout. This structure is of the utmost advantage to the animal in its subterranean search after worms and insects. There is no order of Mammalia in which a greater contrast is exhibited in the external covering of the body than in the different groups of thp Insectivora. The porcupine and the mouse, amongst the Rudentia, do not offer a more remarkable contrast in this respect than do the two families of the Erinaceada and the Talpida. The habits of the hedgehog de- pending for its defence upon the panoply of armour which it presents to its enemies, when rolled up in a compact ball by the muscular apparatus already described, it is furnished on all the upper and lateral parts of the body with hard sharp spines or quills. Fig. 454 Fig. 454. is taken from a drawing by William Bell, engraved in the Hunterian Catalogue, vol. iii. from which also the following description is borrowed: — " On the cut edge of the skin may be seen the roots and sockets of the quills, extending to different depths from the surface, according to the period of their growth : the newly formed ones are lodged deep and ter- minate in a broad basis, the pulp being large and active, and the cavity containing it of cor- responding size; but as the growth of the quill proceeds, the reflected integument forming the socket contracts, and gradually draws the quill nearer the surface; the pulp is at the same time progressively absorbed, and the base of the INSECTIVORA. 1005 quill in consequence gradually increases in size, so that it is at last seen to be attached to the surface of the skin by a very narrow neck, below which the remains of the socket and theca are seen in the form of a small bulb." ( Vig. 454, a.) " A completely formed prickle or quill cut longitudinally and magnified, shewing that it is hollow and filled with a pithy sub- stance, which is transversely disposed, so as to divide the cavity into many sections." But the defence of the animal against attack is not the only object of this modification of the hair. I have more than once seen a hedgehog run to the edge of a precipitous descent, and without a moment's hesitation throw itself over, rolling itself up at the same instant, and on reaching the bottom run off perfectly uninjured. It is unnecessary to point out how perfectly this habit is provided for by the elasticity of the spines, dependent upon their structure, as ex- hibited in the figure. The under parts of the body and the limbs are covered with ordinary hair. The Tenrec and other Erinaceada: re- semble the hedgehog in these respects, and in some species the quills and hair are inter- mixed. The mole, on the other hand, possesses hair •of the softest and most flexible description. In its subterranean galleries, which are not large enough to allow it to turn round, it must often be obliged to retreat backwards ; and the hair therefore is so constructed as to lie equally smooth in every direction. This has been sup- posed to be effected merely by its growing ex- actly perpendicular to the surface of the body ; but it is in fact still more effectually provided for by a remarkable form of the hair itself. Each hair consists of three or four broader portions connected by intervening portions of extreme tenuity; so that there are several points in the length of each hair which pre- sent no appreciable resistance. The hair of the shrews is similarly constructed, and in each case it is to this structure that the pecu- liar and beautiful softness which characterizes it is owing. It is worthy of remark that the colouring matter of the hair exists only in the broader portions, the intermediate parts being wholly colourless. V. Organs of reproduction. — The repro- ductive organs of the Insectivora offer, in several instances, some remarkable peculiari- ties. The subterranean life of many of these animals renders the meeting of the sexes in their natural haunts a matter of almost for- tuitous occurrence ; and it is therefore neces- sary that the sexual desire should in the male be sufficiently powerful to force him as it were to seek and pursue the other sex through all the difficulties and disadvantages occasioned by their peculiar habits. Hence we find that in most of them the male organs are developed to an extraordinary degree ; and in the mole the enlargement of the testes as the season of pairing advances is as remarkable as it is in the sparrow or in any other example of this sea- sonal increase of those organs. Two incom- patible statements have been made respecting s.lie testes in the mole. Cuvier asserts that they make their appearance externally during the season of propagation. Blumenbach de- clares that they belong to the true testiconda, with the hedgehog, &c. The truth is, as de- monstrated with his usual ingenuity by Geof- roy St. Hilaire, that the testicles of the mole never make their appearance externally, al- though during the season of their greatest de- velopement they would do so but for the peculiar construction of the parts in which the organs of generation in this animal are con- tained ; for the abdominal cavity extends be- yond the pelvis, as far as the first four coccy- geal vertebra, which in fact do not, properly speaking, in any degree constitute the tail, which is formed only of the posterior seven vertebra, and the testes during the season are protruded so as to lie concealed under this portion of the caudal division of the spine, which forms as it were a continuation of the upper part of the pelvis. In the hedgehog the testes remain within the abdomen excepting during the spring, and even then they are but little protruded. The object of their being thus generally protected is obvious : in the hedgehog these organs, if external, would be exposed to danger from the act of rolling itself up, and in the mole and its congeners they would interfere with the act of excavating their subterranean passages. The penis in the mole possesses a remarkable peculiarity, which doubtless has reference to the condition of the female organ presently to be described. It consists in a small terminal bony appendage, covered but slightly by integument; it was considered by Daubenton as the os penis, but from its different situation it may be doubtful perhaps if it be in truth analogous to that part. The male organs are in the hedgehog deve- loped to an extraordinary degree, more espe- cially the vesicula seminales. The testes are of an oval form, smooth, and although large in proportion to the size of the animal, are much smaller than the vesiculae seminales ; these are of enormous size, each consisting of four or five fascicles of extremely convoluted tubes, the membranous parietes of which are ex- tremely thin and fragile. Cowper's glands and the prostatic gland are also of considerable size in this animal. The orifices of the vasa defe- rentia, vesicula seminales, prostatic gland, and Cowper's glands all open within the foramen caecum of the urethra. The female organs in the mole offer some peculiarities which deserve more attention than they have hitherto received. In the first place, it appears that in this animal the urinary and genital orifices are Fig. 455. i 2 1006 INSECTIVORA. wholly distinct. The clitoris, (Jig. 455, c,) which is of considerable length, and very much resembles the penis of the male, is pierced for the passage of the urine, and thus constitutes a true urinary penis. Beyond this is a trans- verse slit of a slightly crescentic form, (Jig. 455, 2), which constitutes the opening of the vagina. There are none of those duplicatures of the integument which in other Mammalia constitute the labia and nymphce, but the skin is smooth. But one of the most curious points in the structure of these parts is that in the virgin state this vaginal aperture does not exist, (Jig. 455, 1,) the skin being per- fectly and tightly drawn over the entrance ; so that there are in this state but two openings, the urethral and the intestinal. So perfectly is this the case that it is very difficult to know a virgin female mole from the male by mere external examination. As this covering is so tense, the utility of the little bone at the extremity of the penis in the male is very obvious, and its pointed and tapering form is at once accounted for : it is clearly intended to perforate this tense covering to the vagina. Another peculiarity in this animal is that the abdominal cavity being extended greatly be- yond the pelvis, the vagina, the rectum, and the urinary passage terminate considerably fur- ther back than in other animals. The opening of the rectum is opposite to the articulation of the fourth with the fifth caudal vertebra. The uterus is of considerable size in the mole, and its cornua much convoluted. For Bibliography, see that of Mammalia. (T. Bell.) ANALYTICAL INDEX TO THE SECOND VOLUME. DIAPHRAGM (in anatomy generally), 1 Diaphragm (in human anatomy), 1 costal, upper, true or greater muscle, 2 septum transversum, 2 centrum tendineum, cordiform tentfon, 2 ligamentum arcuatum — externum, 3 internum, S vertebral or smaller muscle, crura pillars or appen- dices, 3 foramina or openings, 3 foramen quadratum s. vennsum, 3 elipticum s. oesopliageum, 3 aorticum, 3 other smaller foramina, 4 relations to the pleura;, peritonaeum, &c. 4 arteries, 4 veins, 4 lymphatics, 4 nerves, 4 uses, 4 malformations and diseases, 6 absence, 6 openings, 6 ulcers, 6 wounds, 6 rupture, 6 inflammation, 6 gangrene, collections of pus, tumours, &c. 6 cartilaginous and osseous deposits, 6 displacement from ascites, &c. 6 Digestion, 6 I. Description of the organs of digestion, 7 mouth with its appendages, the lips, &c. 8 teeth, 8 saliv-iry glands, 8 oesophagus and deglutition, 8 stomach, 9 intestinal canal, 10 peculiarities of the digestive organs in different classes, 11 II. An account of the nature of the substances usually employed as food, 12 animal compounds, 13 vegetable substances, 13 liquids, 14 condiments, 15 medicaments, 15 III. An account of the changes which the food ex- periences in the process of digestion, 15 chymification, 16 physical and chemical properties of the gastric juice, 17 chylirication, 19 analysis of chyle, 19 IV. Theory of digestion, 21 V. Peculiar affections of the digestive organs, 25 Digestive canal (comparative anatomy), 27 I. Polygastrica, 28 Echinodermata, 30 systematic arrangement, 30 I, Tegumentary system, 31 in the Asterias, 31 in the Echini, 32 in the Holothuriae, 33 II. Organs of motion, 34 in Asterias, 34 Echinodermata (continued), in Echini, 35 in HolothuriEe, 36 III. Digestive organs, 36 in Asterias, 36 in Echini, 38 in Holothuriae, 39 IV. Respiratory organs, 40 in Asterias, 40 in the Echini, 41 in Holothurice, 41 V. Vascular system, 41 in the Asterias, 41 in the Echini, 43 in the Holothuriae, 43 VI. Nervous system, 44 VII. Generative organs, 44 in the Asterias, 45 in the Echini, 45 in Holothuriae, 45 VIII. Regeneration of lost parte, 45 Edentata, 46 osseous system, 48 skull, 48 vertebral column, 49 pelvis, 50 anterior extremity, 50 posterior extremity, 50 of the Edentata proper, 51 digestive organs, 53 organs of circulation, 54 tegumentary system, 54 Elasticity, 55 general remarks, laws, &c. 56 tissues of the body in the order of their elasticity, 58 yellow fibrous tissue, 58 cartilage, 58 fibro-cartilage, 58 skin, 59 cellular tissue, 59 muscle, 59 bone, 59 mucous membrane, 59 serous membrane, 60 nervous matter, 60 fibrous membrane, 60 instances in which elasticity plays an important part in the mechanism of organized beings, 60 in the protection of the body and its parts, 60 as a substitute for muscular contraction, 61 as preserving the patulous condition of certain outlets, 61 as subservient to locomotion, or movement gene- rally, 61 as a means of dividing or transferring muscular force, 62 converting occasional into conti- nued forces, 62 Elbow, fold or bend of the arm, 62 skin and subcutaneous tissue, 63 veins, 63 nerves, 64 aponeurosis, 64 brachial artery, 64 development, 64 varieties, 65 selection of a vein for phlebotomy, 65 1008 ANALYTICAL INDEX. Elbow, articulation of the, 65 bones, 65 ligaments, 66 motions, 67 lateral motion, 67 Elbow-joint, abnormal conditions of the, 67 I. Accidents, 68 simple fractures, 68 of the humerus and its condyles, 68 of the ulna, 69 of the olecranon, 69 luxations, 69 of both bones of the fore-arm back- wards, 69 of the bones of the fore-arm laterally, 71 backwards and outwards, 72 backwards and inwards, 72 of the ulna alone directly backwards, 72 upper extremity of the radius from the humerus and ulna, 72 of the radius forwards, 73 radius alone laterally, 73 radius alone backwards, 74 subluxation of die upper extremity of the radius with elongation of the coronary ligament, 74 congenital or original, of the upper head of the radius backward, 75 U. Diseases, 77 of the synovial membrane, synovitis, 77 of the cartilages — inflammation, softening, ab- sorption, 77 of the bones — caries, elastic white swelling, 78 rheumatism, 79 Electricity, animal, 81 electrical fishes, 81 circumstances under which discharges from electrical fishes take place, 82 motions of the fish in the act of discharging, 83 physiological effects of the discharge, 83 magnetical effects of the discharge, 85 chemical effects of the discharge, 86 results of experiments on the transmission of the dis- charge through various conducting bodies, 86 production of a spark and evolution of heat, 87 anatomy of the electrical organs, 87 in the torpedo, S8 in the gymnotus, 91 in the silurus, 53 analogies of animal electricity, 93 manifestations of common electricity in animal sub- stances and in living animals, 95 uses of animal electricity, 97 Encephalon, 98 Endosmosis, 98 measurement of the amount of endosmosis, 98 strength of endosmosis, 98 effects of temperature, 100 explanation of the phenomena, 100 circumstances in which endosmosis occurs, 110 Entozoa, 111 definition, 111 primary division into three classes— Protelmintha, Sterelmintha, and t'oelelmintha, 111 families of the first class, Protelmintha: Cercariadae, ) 1 1 Spermatozoa, 111 Vibrionidae, 113 Trichina spiralis, 1 13 families of the second class, Sterelmintha, equivalent to the Orders ot Rudolphi, 115 Cystica, 115 Cestoidea, 116 Tremaloda, 1 16 Acanthocephala, 1 16 families of the third class, Ccelelmintha, 116 Nematoidea, 116 Acanthotheca, 116 description of species of human entozoa belonging to the above Orders, 117 Acephalocystis endogena, Pill-box Hydatid, 1 17 Echinococcus hominis, 117 Cysticercus cellulosa, 118 Bothriocephalus latus, 120 Taenia solium, 120 Distoma hepaticuin, 121 Polystoma pinguicola, 121 venarum, 121 Diplostomum volvens, 121 Filiaria Medinensis, 122 oculi humani, 122 bronchialis, 122 Trichocephalus dispar, 122 Spiroptera hominis, 123 Strongylus gigas, 125 Ascaris lumbricoides, 125 vermicularis, 125 tabular view of Entozoa hominis, 126 anatomy of the Entozoa, 126 tegumentary system, 126 epidermic processes or spines, 127 * A". C. Sk.:A« Entozoa (continual). muscular sy6tem, 127 nervous system, 129 digestive organs, 131 respiratory organs, 136 excretory glands, 136 organs of generation, 137 Erectile tissue, 144 Excretion, 147 I. Necessity of excretion, 148 II. Products to be held excretions, 149 excretions from the lungs, 149 skin, 149 bowels, 149 kidneys — urine, 149 excrementitious and recrementitious secretions, 150 III. Effects of the suppression of secretions on the animal economy, 150 IV. Manner in which excretions are effected, 150 V. Matters of excretion are separated from the blood rather than formed at the parts where they ap- pear, 151 VI. Original source of the matters thrown out by ex- cretion, 152 Extremity (in human anatomy), 154 superior extremity, 154 clavicle, 154 structure, 156 development, 156 scapula, 156 structure, 159 development, 159 humerus, 159 structure, 161 development, 161 fore-arm : ulna, 162 structure, 163 radius, 163 structure, 164 development of radius and ulna, 164 hand, 165 inferior extremity, 165 femur, 165 structure, 167 development, 167 patella, 168 structure and development, 168 leg: tibia, 168 structure, 170 fibula, 170 structure, 171 development of the bones of the leg, 171 abnormal conditions of the bones of the extremi- ties, 171 Eye: general view, 171 sclerotic coat or membrane, 174 cotnea, 175 ■choroid coat, 178 tapetum, 179 orbiculus s. circulus ciliaris, ciliary circle, 180 corpus ciliare, ciliary processes, 180 pigmentum nigrum, 180 iris, 182 membrana pupillaris, 184 retina, 185 lamina cribosa, 185 porus opticus, 186 layers or membranes, 186 foramen centrale, orforamen of Soemmerring, 188 vitreous humour, 19! canal of Petit, 192 corona ciliaris, 193 crystalline lens, 194 capsule, 199 aqueous humour, 201 peclen s. marsupium nigrum, 203 choroid gland or muscle, 205 Face (in anatomy generally and in human anatomy), 207 I. Bones of the face, 207 superior maxillary bones, 207 maxillary sinus, 209 connexions of the maxillary bone, 209 structure, 209 development, 209 ossa intermaxillaria, 210 palate bones, 210 connexions, 211 structure and development, 211 malar bones, 211 connexions, 211 structure and development, 212 nasal bones, 212 connexions, 212 structure and development, 212 lachrymal bones, 212 mnexions, 212 .[^structure and development, 212 fnfeffej^turbinated or spongy bones, 21J ,.4 ■■ h ANALYTICAL INDEX. 1009 Face (continued). connexions, <2\$ structure and development, 213 vomer, ^13 connexions, 213 structure and development, 213 lower jaw bone, 213 structure, 215 connexions and uses, 215 development, 215 of the face in general. Dimensions, 215 mechanism of the face, 217 development of the face, 218 articulations of the face, 219 abnormal conditions of the bones of the face, 219 II. Muscles of the face, 220 orbicularis palpebrarum, 221 relations, 221 action, 221 corrugatoi supercilii, 222 levator palpebral superioris, 222 relations and action, 222 muscles of the nasal region : pyramidalis, 222 levator labii superioris alaeque nasi, 222 relations and action, 222 triangularis nasi, 223 relations and action, 223 depressor ala nasi (myrtiformis), 223 relations, 223 dilator alee nasi, 223 muscles of the labial region; oibicularis, 223 relations, 223 actions, 224 naso-labialis, 224 levator labii superioris, 224 relations and action, 224 zygomalicus minor, 224 relations and action, 224 zygomaticus major, 224 relations and action, 224 levator anguli oris, 224 relations and action, 224 depressor anguli oris (triangularis oris), 225 relations, action, 225 depressor labii inferioris (quadrants menti), 225 relations and action, 225 levator menti (houppe du menton), 225 action, 225 buccinator, 225 relations and action, 220 platysma myoides, 2^6 general review of the muscles of the face, 227 III. Integuments of the face, 227 IV. Vessels of the face, 227 V. Nerves of the face, 228 VI. Abnormal conditions of the soft parts of the face, 228 Fascia, 229 1. Cellular fasciae, 229 2. Aponeuroses, or aponeurotic fascise, 231 Fat, 031 varieties of fat : lard, 232 human fat, 232 fat of beef, 233 neat's foot oil, 233 goat's fat, 233 mutton fat, 233 whale or train oil, 233 spermaceti oil, 233 phocenine, 234 fat of birds, 234 fat of insects, 235 adipocere, 235 Femoral urtery, 235 course and relations generally, 235 femoral canal and femoral sheath, 237 particular course and relations, 237 in its superior portion, 237 in its second or middle portion, 242 in its inferior portion, 242 varieties, 243 branches of the femoral artery, 243 superficial epigastric, 243 external pndic, 244 anterior iliac, 244 profunda femoris, 245 branches of the profunda, 246 external circumflex, 246 internal circumflex, 247 first perforating artery, 248 second peiforating artery, 248 third perforating artery, 248 termination of the profunda, 249 anastomoiica magna, or superficial supe- rior internal articular, 249 other branches, and considerations on the collateral circulation of the thigh, 249 Fevwrul artery (continued) . anastomoses of the branches of the femoral ar- tery, 250 effects of obstructions at different points in the course of the artery, 251 operative relations of the femoral artery, 252 Fibrine, 257 Fibro-cartHage, 260 morbid conditions of, 262 Fibrous tissue, 263 white fibrous organs, 263 yellow elastic fihrous organs, 263 I. White fibrous organs, 263 bloodvessels, 263 absorbents, 263 nerves, 263 chemical properties, 263 physical properties, 263 periosteum, 264 fascia?, 264 tendinous sheaths, 264 fibrous coverings, 264 ligaments, 264 tendons, 265 II. Yellow elastic fibrous organs (tela elastica), 265 organization and properties, 265 morbid anatomy of the fibrous tissues : inflammation, 266 cartildginous transformation and ossification, 966 fungus, 266 osteo-sarcoma, Q67 Fibular artery, (arteria peroncea,) 267 branches : anterior peionceal, 257 posterior peronceal, 267 Fifth pair of nerves, trigeminal or trifacial nerve, 268 general structure and encephalic connexions, 268 external or extracephalic portion of the nerve, 278 first or ophthalmic division, 279 its branches : recurrent branch of the first division, 279 frontal nerve, 279 nasal nerve, 281 lachrymal, 282 second division of the fifth or superior maxillary nerve, 283 its branches : temporo-malar, 284 spheno-palaline, 284 spheno-palaiine ganglion, or ganglion of Meckel, 285 posterior-superior dental, 289 anterior-superior dental, 289 facial branches, 289 third division of the filth or inferior maxillary nerve,2QO its branches : the masseteric, 201 the deep temporals, 291 the buccal, 291 the pterygoid, 291 otic, or auricular ganglion of Arnold, 292 the superficial temporals, 293 the inlerior maxillary or dental, 294 the lingual, 295 chorda tympani, 295 submaxillary ganglion, 297 ganglion of the lift h nerve, ganglion semilunare Gas- serii, 298 vital properties of the fifth pair of nerves, 299 sensibility, 299 influence upon sensation and volition, 29£> Bell's experiments, 299 Magendie's experiments, 300 Mayo's experiments, 300 relation to the special senses, 305 smell, 305 vision, 307 hearing, 309 influence upon the nutrition of the parts to whicfi it is distributed, 309 progression, 315 influence of disease on the functions of the nerve, 316 Fatus (normal anatomy), sub voce Ovum Feetus (abnormal anatomy), 316 atrophy, 318 hernia?, 319 hernia cerebri, encephaloccle, 320 spina bifida, 321 cranial tumours, 323 injuries of the cranial bones, 323 fractures of the long bones, 324 mutilations, separation of parts already formed, 324 convulsive affections, 329 effects of mental impressions on the mother, 330 effects of inflammation, organic lesions, &c. 330 in the stomach and bowels, 331 liver, 331 lungs, 331 3 u 1010 ANALYTICAL INDEX. Fcetus (continued), pleuritis, 332 purulent effusions, 33'2 dropsical effusions, 33*2 induration of the cellular tissue, 332 cutaneous affections, 333 affections of the heart and pericardium, 334 pericarditis, 334 thymus, 334 thyroid gland, S35 abnormal conditions of the fcetal bladder, 335 urinary deposits, 336 premature development of teeth, 336 intestinal worms, 336 imperforate anus, 336 rickets, 337 jaundice, 337 cirronosis, 337 accidental morbid tissues, 337 Foot, bones of the, 338 tarsus, 339 astragalus, 339 os calcis, 339 os cuboides, 340 os scaphoides, 340 ossa cuneiformia, 340 structure of the tarsal bones, 341 development, 341 metatarsus, 341 structure and development of its bones, 342 toes : their phalanges, &c. 342 joints of the tarsus, 342 anterior astragalo-calcanien articulation, 342 cuneo-scaphoid articulation, 343 cuboido-cuneen articulation, 343 articulation of the two rows of tarsal bones to each other, 343 astragalo-scaphoid articulation, 343 calcaneo -cuboid articulation, 343 motions o< the tarsal joints, 3-44 tarso-metatarsal articulations, 344 metatarsal articulations, 345 metatarso-phalangeal articulations, 345 articulations of the toes, 345 motions of the metatarsal joints, 345 metatarso-phalangeal joints, 345 phalangeal joints, 345 general mechanism and endowments of the foot, arches, &c. 346 Foot, abnormal conditions of the, 347 dislocations, 347 congenital displacements of the bones, 347 distortions, 348 varus, 348 valgus, 348 pes equinus, 349 flat-foot, 350 Foot, regions of the, 351 dorsum, 351 integuments and subcutaneous cellular tissue, veins, &c. 351 fascia and aponeurosis, 352 region of the toes, 353 plantar region, 353 proper plantar legion, 353 fascia plantaris, 354 deep-seated parts, 354 plantar region of the toes, 355 practical inferences, 355 Foot, muscles of the, 357 of the dorsum : extensor brevis digitorum, 357 interossei extend s. dorsales, 358 of the plantar region : abductor pollicis, 353 flexor brevis pollicis, 358 adductor pollicis, 358 abductor minimi digiti, 358 flexor brevis minimi digiti, 358 flexor brevis digitorum s. perforatus, 358 flexor digitorum accessorius s. massacarnea Jacobi Sylvii, 358 lumbiicales, 358 interossei interni s. plantares, 358 transversalis pedis, 358 classification of the muscles of the foot according to their effects, 359 Fore-arm, (surgical anatomy,) 361 integuments, and parts immediately subjacent, 361 aponeurosis, 362 vessels, 363 fracture of the fore-arm, 364 Fore-arm, muscles of the, 365 in the anterior region, 366 supinator radii longus, 366 extensor carpi radialis longior, 366 pronator radii teres, 366 flexor carpi radialis, 366 palmaris longus, 367 flexor communis digitorum sublhuis s. perfora- tus, 367 Fore^arm, (continued), flexor carpi ulnaris, 367 flexor longus proprius pollicis, 368 flexor communis digitorum profundus s. peifo- rans, 368 pronator quadratus, 368 in the posterior legion, 368 anconeus, 368 extensor carpi ulnaris, 369 extensor communis digitorum, 369 extensor carpi radialis brevior, 369 supinator radii brevis, 369 extensor ossis metacarpi pollicis, 369 extensor primi internodii pollicis, S70 extensor secundi internodii nollicis, 370 indicator s. extensor proprius primi digiti manus, 370 Fourth pair of nerves, 370 Ganglion, 37 1 organization, 372 reddish grey matter, 372 fibres, 374 arrangement ot_the fibres in ganglia, 374 nature of the fibres connected with ganglia, 375 coverings, 376 bloodvessels, 376 chemical composition, 376 Gasteropoda, 377 characters of the class, 377 division into orders, 377 tegumental^ system, 379 growth of shell, 380 operculum, 384 organs of digestion, 384 mouth, 384 alimentary canal, 384 accessory glands, 388 salivary glands, 38a biliary system, 388 organs of respiration, 3ho organs of circulation, 390 nervous system, 392 common sensation, 394 touch, taste, smell, 394 vision, 395 generative system, 396 ova, 401 reproduction of lost parts, 402 muscular integument, 402 body, 402 retractile muscles, 403 foot, 403 particular secretions, 404 Gelatin, 404 Generation, (in human and comparative anatomy,) organs and means of, 406 fissiparous generation, 407 gemmiparous generation, 407 oviparous generation, 407 I. Division.— Animals in which ovigerous organs only have been distinctly recognized, 409 II. Division. — Animals provided with ovigerous organs combined with an additional secreting structure, probably subservient to the fertili- zation of the ova, 410 III. Division. — Ovigerous and impregnating or- gans co-existent, but the cooperation of two individuals necessary for mutual impregna- tion, 411 IV. Division. — Sexes distinct, i. e. ovigerous and impregnating organs placed in separate indi- viduals, 412 Insects, 413 Arachnida, 417 Crustacea, 417 Mollusca, 417 Vertebrate ovipara, 418 Fishes, 418 Reptiles, 419 Birds, 421 Mammalia, 42i testes, 422 prostate, 422 Cowper's glands, 422 accessory vesicles, 423 penis, structure of, 423 Generation, (in physiology,) 424 I. Function of reproduction generally considered, 426 introductory remarks, 426 theories of generation, 427 spontaneous generation of animals, 429 II. Sketch of the principal forms of the reproductive function in different animals, 432 1. Non-sexual reproduction, 432 fissiparous generation, 432 gemmiparous generation, 433 reproduction by separated buds or sporules, 433 2. Sexual reproduction, 434 nature of the ovum, 434 hermaphrodite generation, 434 ANALYTICAL INDEX. 1011 Generation, (continued) . dioecious reproduction, or with distinct in- dividuals of different sexes. Oviparous and viviparous generation, 435 ovoviparous generation, 435 varieties in respect to utero-gestalion and the development of the young, 43b' Marsupiate generation, 436 Monotrematous generation, 437 comparison of animal and vegetable repro- duction, 437 synoptical table of the various forms of the reproductive process, 438 III. Reproductive function in man and the higher animals : I. sketch of this function in man, 438 organs of reproduction, 438 puberty, 439 structural differences of the sexes, 439 menstruation, 439 periodical heat in animals, 441 age at which pubcriy occurs, 44 l period during which the generative function is exercised, 442 effects of castration, 443 sexual feeling, 443 relation of reproduction to the bruin, 444 distinction of species. Mules, 444 functions of the external organs of repro- duction, 445 erection, 445 IV. Changes consequent on fruitful sexual union : 1. As regards the female. Conception, 447 approximation of the fimbriated extrt mities or the Fallopian tubes to the ovary, 447 changes in the ovaries: bursting of the Graafian vesicles, 443 formation of the corpus luteum, 449 descent of the ovum. Its structure and changes during its passage, 451 time at which it arrives in the uterus, 453 changes in the uterus after conception, 454 irregularities in the descent of the ovum, 455 circumstances influencing liability to con- ception, 456 signs of recent conception in women, 4 57 2. As regards the male, 4b7 properties of the seminal fluid, 457 chemical properties, 458 spermatic animalcules, 459 table of their sizes in different animals, 460 circumstances upon which the fecundating property of the seminal fluid depends, 46) difference between the fecundated and uufe- cundated ovum, 462 is material contact of the semen and ovum necessary ? 462 external and artificial fecundation, 462 courseof the seminal fluid within the female organs, 464 nature of the fecundating print iple. Hypo- thesis of an aura, &c. 466 general conclusions respecting fecundation, 467 V. Miscellaneous topics relating to the preceding history of generation, 468 1. superlactation, 469 2. influence exerted by parents on the qualities of their offspring, 470 3. number of children and relative proportion of the male and female sexes, 478 table of the proportion of males to females born in different countries, 47S Gland, 480 divisions and kinds of glands, 431 situations, 481 organization, 481 minute structure, 481 excretory ducts, 486 structure of the secreting canals and excretory ducts, 487 bloodvessels, 487 arrangement of their minute subdivisions, 488 lymphatics, 489 nerves, 489 interstitial cellular tissue, 489 investing membrane, 489 general conclusions regarding the minute struc- ture of glands, 490 hypotheses on this subject, 490 development of glands, 492 Glosso-pharyngeal nerve, 492 origin and course, ganglion jugulare, ramus tympa- nicus or nerve of Jacobson, &c. 492 digastric and stylo-hyoid branch, 496 carotid branches, 496 pharyngeal branches, 496 lingual blanches, 497 tonsillitic branches, 497 physiology of this nerve, 497 G lit tceal Region, (in surgical anatomy,) 500 Groin, Region of the, (in surgical anatomy,) 503 Hcematosine, 503 Hair. Vide Tegumentary System, 505 Hand, Bones oj the, (human anatomy,) 505 I. Carpus, 505 os naviculare, 505 os lunare, 505 os cuneiforme, 505 os pisiforme, 505 os trapezium, 506 os trapezoides, 506 os magnum, 506 os unciforme, 506 structure and development of the bones of carpus, 506 II. Metacarpus : first, second, third, fourth, and fifth metacarpal bones, 507 structure and development of the metacarpus, 507 III. Fingers, 507 metacarpal, middle, and ungual phalange?, 507 structure and development, 507 joints of the hand : joints of the carpus, 508 articulaiion of the two rows of carpal bones to each other, 508 motions of the carpal articulations, 503 articulation of the pisiform bone, 508 carpo-me tacarpal joints, 509 motions of the carpo-metacarpal joints, 509 joints of the fingers : metacarpophalangeal joints, 510 phalangeal joints, M0 motions o( the joints of the finders, 510 Hand, Abnormal Conditions oj the, 510 I. As results of accidents, 510 luxations and fractures, 510 luxation of the bones of the carpus, 510 luxation of the bones of the meiacaipus, 511 luxation of the metacarpal bone of the thumb, 511 luxation of the phalanges of t lie fingers, 511 first phalanx of the thumb from the metacarpal bone, 511 anatomical characters of this accident, 512 luxation ot the second and third phalanges, 514 II. Diseased conditions ; spina ventosa, case of, 514 strumous osteitis, 516 malignant tumours, 516 abnormal conditions of the fingers, the result of accidents, and morbid affections of one or more of theirconstituent structures, 517 contraction of ihe fingers from disease of the palmar fascia, 517 anchylosis of the joints of the phalanges, 518 III. Congenital malformations of the hand, 519 Hand, Muscles of the, (human anatomy,) 519 I. Muscles of the palm : a. muscles of the external palmar region, 519 abductor pollicis, 519 relations, 5 19 flexor ossis metacarpi s. opponens pollicis, 519 relations, 590 flexor brevis pollicis, 520 relations, 520 adductor pollicis, 520 relations, 520 b. muscles of the internal palmar region, 520 palmaris brevis, 520 relations, 520 abductor minimi digiti, 520 relations, use, 520 flexor brevis minimi digiti, 521 relations, 521 adductor ossis metacarpi s. opponens minims digiti, 521 relations, 521 c. muscles of the middle palmar region, 521 Iumbricales, 521 relations and uses, 521 intcrossei interni ditiitorum, 521 relations, use, 521 II. Muscles of the dorsum : interossei externi, 521 relations, uses, 522 motions of the hand and its parts, 522 Hand, Regions of the, (surgical anatomy), 523 I. Palmar region, 523 skin, 524 subcutaneous cellular tissue and nerves, 524 aponeurosis, 524 anterior annular ligament, 524 palm, u* fascia, 525 vessels and nerves : ulnar artery, 525 radial artery, 526 veins, lymphatics, nerves, 526 median nerve, 527 1012 ANALYTICAL INDEX. Hand, Regions of the, (continued). ulnar nerve, 527 muscles and tendons, 527 II. Dorsal region, 527 skin, 528 subcutaneous layer and veins, 508 aponeurosis, 5'28 nerves, 528 tendons and muscles, 528 arteries, 529 remarks on amputations of dilFerent members of tlie hand, 529 Hearing, Organ of. The ear, 529 1. The ear-bulb or fundamental organ of hearing, 529 1. osseous labyrinth, 5_>9 vestibule, 530 semicircular canals, 530 cochlea, 53 l canalis spiralis, 531 axis, modiolus, columella or central pil- lar, 53 I lamina spiralis, spiral lamina, and scala;, 532 the aqueducts, 532 membrane lining the labyrinthic cavity, 533 of the cochlea in the recent stale, 533 farther observations on the aqueducts, 536 of the liquid of the labyrinthic cavity, pe- rilymph, or liquid of Cotugno, 53S 2. membranous labyrinth, 536 common sinus, membranous ampullae, and membranous semicircular tubes, 537 saccule, sacctilus rotundus, 538 liquid of the membranous labyrinth, endo- lymph or vitreous humour of the ear, 538 of the masses of calcareous matter contained within the membranous labyrinth, otolithi and otoconia, 539 auditory or acoustic nerve and its divisions, 539 bloodvessels of the labyrinth, 512 arterir cochlea? and arteria vestibuli, 542 I!. Accessory parts of the apparatus of hearing, 543 I. Middle ear or tympanum and its appendages: cavity of the tympanum, 543 promontory, fenestra rotunda, and fenes- tra ovalis, 543 eminentia papillaris s. protuberantia py- ramidalis, 544 cochleariform process, 544 osseous portion of tlie auditory passage, 544 tympanic ring, 544 membrane of the tympanum, 545 structure of the proper membrane, 545 hiatus Rivinianus, 546 the ossicles or small bones of the ear, 546 malleus or hammer bone, 546 incus or anvil-bone, 546 stapes or stirrup-bone, 547 position, connexions, and articulations of the small bones of the ear, 547 muscles of the small bones, 548 internus mallei s. tensor tympani, 548 stapedius, muscle of the stapes, 549 lining membrane of the cavity of the tym- panum, 549 the Eustachian tube, 549 osseous part, 549 cartilaginous and membranous por- tion, 550 2. The external ear, including the auditory pas- sage, 5 SO A. The auricle, auricula s. pinna, 550 helix, 550 antihelix, 551 antitragus, 551 tragus, 551 ligaments of the ear: anterior ligament and posterior ligament, 651 muscles of the ear : muscles which move the ear as a whole, or extrinsic muscles : elevator auris, attollens auriculam, 551 retractor muscles, retrahentes auri- culam, 552 anterior muscle, attrahens auricu- Iam, 552 intrinsic muscles of the ear: helicis major, 552 helicis minor, 552 tragicus, 552 antitragicus, 552 transversus auriculae, 552 B. The external auditory passage, meatus audito- rius externus, 552 the cartilaginous and membranous por- tion, 552 incisurae Santorinianaj, 553 ceruminous glands, 553 Hearing, Organ of, (continued) . nerves of the accessory parts of the apparatus of hearing, 554 nerves of the tympanum, 554 nervus petrosus superficialis, 554 intumescentia gangliformis nervi fa- cialis, 554 chorda tympani, 554 ramus auricularis nervi vagi, 554 nervous anastomosis in the tym- panum, 554 nervus lympanicus, 554 nerves of the auricle and auditory pas- sage, 555 arteries of the external ear and tympanum, 556 III. 1. development and abnormal conditions of the organ of hearing, 5S7 A. of the ear-bulb, 557 B. of the tympanum and its contents : — cavity of the tympanum, 559 small bones of the tympanum, 560 C. of the external ear, 561 IV. parallel between the ear and the eye, 562 Hearing, (in physiology,) 564 preliminary observations on sound, 565 pitch, intensity, and quality in musical sounds, 566 reflexion of sound, 565 part performed by each portion of the auditory appa- ratus in the function of hearing : — I. the internal ear, 567 vestibule, the essential part, 567 office of the otolithes, 567 function of the cochlea, 568 function of the semicircular canals and sinus commune, 669 II. The accessory parts of the organ, 571 the auricle, 571 the tympanum and its contents, 572 Eustachian tube, 576 functions of the nerves, 576 Heart, (in anatomy,) 577 Human heart (normal anatomy) : position, 578 form and external surface, 578 right auricle, 579 external surface, 579 internal surface, 579 tuberculum Loweri, 580 fossa ovalis, vestigium foraniinis ovalis, 5S0 annulus s. isthmus Vieussenii, 5S0 remains of the Eustachian valve, 580 valvula Thebesii, 580 foramina Thebesii, 580 musculi pectinati, 580 auriculo-ventiicular opening, 580 right ventricle, 580 external surface, 5S0 internal surface, 580 colttmnae carnese, 580 musculi papillares, 581 valvula tricuspis s. triglochis, 581 chordae tendinea;, 581 semilunar valves, 581 corpus Arantii, 513 left auricle : external surface, 582 internal surface, 582 left ventricle : external surface, 582 internal surface, 582 bicuspid or mitral valve, 583 semilunar valves, 584 sinuses of Valsalva, 584 septum of the ventricles, 584 thickness of the walls of the several cavities of the heart, 585 measurements, 586 relative capacities of the several cavities, 585 measurements, 586 relative dimensions of the auriculo-ventricular ori- fices, 587 circumference of the aortic and pulmonary orifices, 587 measurements, 587 size and weight of the heart, 587 structure of the heart, 587 tendinous texture, 587 auriculo-ventricular tendinous rings, 587 arterial tendinous rings, 5n7 tendinous structure of the auriculo-ventri- cular valves, 589 tendinous structure in the arterial valves, 589 attachment of the middle coat of the arteries to the arterial tendinous rings, 539 muscular tissue, 590 of the ventricles, 590 of the auricles, 593 inner membrane of the heart, 594 nerves of the heart, 595 middle cardiac nerve, 595 ANALYTICAL INDEX. 1013 Human Heart, (continued.) inferior cardiac nerve, 595 lelt cardiac nerve, 595 cardiac plexus, 596 bloodvessels of the heart, 596 great coronary vein, 596 smaller posterior coronary vein, 597 anterior coronary veins, 597 venae minimse, or veins of Thebesius, 597 sinus of the coronary vein, 597 sympathies of the heart, 5&7 pericardium, 597 uses of the pericardium, 59? relative position of the vessels within the peri- cardium, 598 peculiarities of the foetal heart, 599 value of the foramen ovale, 599 Eustachian valve, 599 Physiology of the heart: mode'of action ol the valves, 600 movements of the heart, 602 systole and diastole of the auricles, 602 ventricles, 603 impulse of the heart, 604 most irritable parts of the heart, 607 duration of contractile power after death, 608 frequency of the heart's action, 609 number of pulsations in different animals, 609 cause of motion of the heart, 610 upon what does the peculiar irritability of the heart depend t 612 constancy of the heart's action, 613 regularity of the heart's movements, 6*13 sounds of the heart, 614 first sound, 6 16 second sound, 617 Heart (arrangement of the fibres of the), 619 Heart (abnormal conditions of the), 630 I. congenital abnormal conditions : congenital aberrations of position, ectopia cordis, 630 malformations by defect of development, 631 malformations of the valves, 633 congenital absence of the pericardium, 633 malformations by excess of development, (i34 anomalous connexions of the vessels of the heart, 635 displacement or ectopia of the heart as a conse- quence of disease, 635 II. morbid alterations of the muscular substance of the heart : inflammation, carditis proper, 635 suppuration, 636 ulceration, 637 induration, 637 cartilaginous and osseous transformations, 637 tubercles, 637 scirrhus, 637 medullary fungus, encephaloid tumours, 637 melanosis, 633 hypertrophy : simple," i.e. without change in the capa- city of the cavities, 638 with dilatation or increased capacity of the cavities, excentric hypertrophy, active aneurism of the heart, 639 dilatation of the cavities of the heart, pas- sive aneurism, 640 dilatation of the oiifices of the heart, 640 aneurism of the heart, 640 atrophy of the heart, 642 morbid deposit of fat on the heart, fatty de- generation, 642 rupture of the heart, 643 morbid states of the membranes of the heart : — morbid states of the pericardium, 643 white spot on the heart, 644 tubercular formations, 645 cysts, 645 hydrops pericardii or hydropericardium, 645 pneumopericardium, 645 morbid states of the endocardium, 645 chronic valvular diseases, 646 dilatation of the valves, 647 nlrophyof the valves, 647 entozoa in the heart, 64" states of the blood in the heart after death, 648 Heat, animal, 648 temperature of the human body, 649 of the mammalia, 649 of birds, 64Q of reptiles, 649 of fishes, 649 of insects, 650 of Crustacea, 650 of mollusca, 650 general conditions of organization in relation with the production of a greater or less degree of heat, 750 temperature of different parts of the body, 654 Heat, animal, (continued.) relations between the temperature of internal parts, 654 relations between the temperature of external parts, 655 difference of temperature according to depth, 656 influence of external temperature generally, 658 variations in temperature independently of external temperature, 658 influence of the natural temperature of the air on that of the body, 65K influence of different media upon temperature, 659 effects of external temperature upon an isolated part of the body, 660 effects of partial heating, 660 effects of excessively high or excessively low ex ternal temperature upon the temperature of the body, 660 influence of evaporation, 661 relations of the bulk of the body to animal heat, 662 relations of age to animal heat, 662 differences of constitution in relation to the pro- duction of heat among animals, 667 influence of the seasons on the production of animal heat, 668 differences according to the nature of the climate, 670 influence of sleep on the production of heat, 670 phenomena presented by hybernating animals with regard to the production of heat, 671 of the system upon which the external temperature acts primarily and principally, 673 influence of temperature on the vitality of cold- blooded animals, 673 influence of temperature on the vitality of warm- blooded animals and of man in the states of health and disease, 674 effects of various other causes of modification in ex- ternal agents, 680 confirmation of the general results, 682 of the physical cause of animal heat, 683 Hermaphroditism, or Hermaphrodism, 684 classification of hermaphroditic malformations, 685 I. spurious hermaphroditism; — ■ A. in the female, 6s5 1. abnormal development or magnitude of the clitoris, 6h6 2. from prolapsus of the uterus, 690 B. in the male, 690 1. extroversion of the urinary bladder, 691 2. adhesion of the inferior surface of the penis to the scrotum, 691 3. fissure of the inferior part of the urethra, perinaeum, &c. 691 II. true hermaphroditism, 695 A. lateral hermaphroditism, 696 1. an ovary on the right side and a testis on the left, 693 2. a testicle on the left and an ovary on the right side, 700 B. transverse hermaphroditism, 701 3. transverse hermaphroditism with external sexual organs of the female type, "01 2. transverse hermaphroditism with the ex- ternal sexual organs of the male type, 704 C. double or vertical hermaphroditism, 706 1. male vesicula: serninalcs, &c. superadded to organs of the female sexual type, 707 2. imperfect female uterus, &c. superadded to asexual organization essentially male in its type, 707 3. Coexistence of female ovaries and male testicles, 71 1 two testicles and one ovary, 712 two testicles and two ovaries, 712 III. hcrmaphrodolism as manifested in the general conformation of the body and in the se- condary sex'ial characters, 714 general summary with regard to the nature of hermaphroditic malformations, 722' 1. of the varieties of spurious hermaphro- ditism, 722 nature of true hermaphroditic malform- ations, 723 anatomical degree of sexual duplicity in her- maphroditism, 728 1. fallacies in judging of the addition of male seminal ducts to a female type of sexuiil organs, 729 2. fallacies in the supposed co-existence of a female uterus with testicles and other organs of a male sexual type, 730 3. fallacies in a supposed co-existence of testicles and ovaries, 731 physiological degree of sexual perfection in her- maphrodites, 732 causes of hermaphroditic malformations, 733 hermaphroditism in double monsters, 736 Hernia, (morbid anatomy,) 738 circumstances under which protrusions of the ab- dominal viscera take place, varieties, &c. 738 1014 ANALYTICAL INDEX. Hernia, (continued.) inguinal hernia, 750 by direct descent, 755 crural or femoral hernia, 756 umbilical hernia, 761 Hibernation, 764 order of consideration of the effects of hibernation, 766 I. of sleep, 766 IT. of the sleep of hibernating animals, 766 III. of perfect hibernation, 768 state of the several functions in hibernation : — sanguification, 768 respiration, 769 comparative temperature of hibernating animals with that of the atmosphere, 770 circulation, 771 defecation, 772 nervous system, 772 irritability, 772 motility of muscular fibre, 773 IV. of reviviscence, 774 V. of torpor from cold, 775 Hip-joint, anatomy of the, (human anatomy,) 776 the bones, 776 acetabulum, 776 head of the femur, 777 cartilage of the acetabulum, 777 fibro-cartilage of ditto, 777 ligaments, 777 round ligament, 778 capsular ligament, 778 synovial membrane, 779 arteries, 779 nerves, 779 motions, 779 Hip-joint, abnormal conditions of the, 780 Sect. 1. congenital malformations of the hip-joint: original luxation, 790 anatomical characters of the affection, 782 history of a case of congenital malformation of the left hip-joint, with the anatomical ex- amination of the articulation, 784 history of a second case, 786 Sect. II. disease: inflammation of the synovial membrane and other structures, 787 synovitis coxa?, with periostitis, 788 cartilages, inflammation and destruction of the, 788 bones, strumous osteitis, morbus coxae, scrofulous affection of the hip-joint, 789 acute arthritis coxae, 790 ' anatomical characters, 792, chronic strumous arthritis coxa?, 70S anatomical characters, 794 chronic rheumatic arthritis coxae, chronic rheu- matism, 798 anatomical characters, 801 Sect. III. accidents : I. fractures : fracture of the fundus of the acetabulum, 802 fracture of the brim of the acetabulum, 803 fracture of the superior extremity of the femur, 804 A. intra-capsular fracture of the neck of the femur, 804 B. extra-capsular fracture of the neck and fracture of the superior portion of the shaft of the femur, 805 C. fracture of the neck of the femur com- plicated with fracture through the tro- chanter major, 805 I). fracture of the neck of the thigh-bone, with impaction of the superior or cotyloid fragment into the cancellated tissue of the upper extremity of the shaft of the femur, 8Qf» anatomical characters of fracture of the neck of the thigh-bone, 807 does bony consolidation of the intra- capsular fracture of the cervix femoris ever occur i 810 II. luxations: dislocation of the head of the femur upwards and backwards on the dorsum of the ilium, 815 anatomical characters of this dislocation, 816 dislocation backwards or towards the ischiatic notch, 818 anatomical characters of this dislocation, 820 dislocation upwards and inwards on the pubes, 820 anatomical characters of this luxation, 821 dislocation downwards and inwards into the foramen ovale, 822 anatomical characters, 823 cases of unusual dislocations, 824 upwards and outwards, 824 downwards and backwards, 824 Hyperemia and /Incemia, (in morbid anatomy,) 825 Hypertrophy and Atrophy, (in morbid anatomy,) 826 Iliac Arteries, 827 primitive iliac arteries, common iliacs, 827 internal iliac artery, 828 branches : 1. internal branches : ilio-lumbar artery, 829 lateral sacral artery, 830 middle hsemorrhoidal artery, 830 vesical arteries, 830 umbilical artery, 830 uterine artery, 831 vaginal artery,, 831 2. external branches : obturator or thyroid artery, 831 glutaeal artery, 833 ischiatic artery, 833 internal pudic artery, 834 branches : external haemorrhoidal arteries, 835 perineal artery, 835 artery of the corpus cavernosum, 836 artery of the dorsum penis, 836 external iliac artery, 837 relations, coverings, connexions, 837 branches : anterior or circumflex iliac artery, 842 epigastric artery, 842 methods of operation for the ligature of the external iliac arteries, 844 comparative merits of the different methods, 846 operations for the ligature of the internal iliac, 849 ligature of the primitive iliac, 849 Jnnuminata Arteria, {human unatomy,) 850 relations, Sec. 850 anomalies, 852 ligature, 852 Instcta, 853 Table of the arrangement of insects according to the system of Mr. Stephens, 856 Order I. Coleoptera, 859 Order II. Dermaptera, 863 Order III. Orthoplera, 864 Order IV. Neuroptera, 864 Older V. Trichoptera, 865 Order VI. Hymenoptera, 865 Order VII, Strepsptera, 866 Sub-class, Haustellata: Order VIII. Lepidoptera, 866 Order IX. Diptera, 867 Order X. Homaloptera, 867 Order XI. Aphaniptera, 867 Order XI I. Aptera, 868 Order XIII. Hemiptera, 868 Order XIV. Homoptera, 868 Different states of existence : the eeg, 869 the larva, 869 external anatomy of the larva, 870 of the head, 872 organs of locomotion, 873 grow ih and changes of the larva, 874 the pupa, nymph, aurelia or chrysalis, 879 the imago or perfect state, 880 Dermo-skeleton, 8b I its chemical composition: chitine, 881 its thirteen segments, 882 articulations, 883 table of the parts and appendages of the head, 885 account of these, 885 mandibles, 888 maxilla?, 889 antennae, 890 internal parts of the head, 892 mouth, 897 development of the head, 9O9 thorax, 911 table of parts, 9 13 pro-thorax, 914 mesu-thorax, 914 meta-thorax, 915 abdomen, 918 Organs of locomotion.— The wings, 924 articulations of the wings, 926 lieuration, 926 Hie, 928 the legs, 931 aberrations of form in the organs of locomotion, 933 muscular system, 934 muscles of the larva, 935 perfect insect, 939 nervous system : in the larva, 943 nerves of the head, 594 of the perfect insect, 948 organs of vision, 960 organ of hearing, 96I organ of touch, 961 ori>an of smell, 962 development of the brain and nervous system, 962 ANALYTICAL INDEX. 1015 Insecta, (continued.) organs ot nutrition : alimentary canal and its appendages, 963 peritoneal coat, 963 muscular coat, 963 mucous coatf 966 alimentary canal of larva, 966 appendages of the canal, 973 anal or proper uriniferous organs, 975 adipose tissue, 975 circulatory system, 976 the heart or great dorsal vessel, 976 organs of respiration, 982 Insecta (x-ontinued*) function of respiration, 987 organs of generation, Q90 tegumentary appendages — hair, scales, and spines, 993 Insectivora, 9QA families, 994 osteology, 995 muscles, 998 digestive organs, 1000 teeth, 1000 nervous system, 1002 tegumemary system, 1004 organs of reproduction, 1005 END OF VOL. II. ERRATA IN VOLUME II. Page 153, col. \, line 13 from bottom, for articulated, read reticulated. 157, col. 2, line 20 from bottom, for supra-spinata, read infra-spinata. 174, note, dele " and copied into Mr. Mackenzie's work on the eye.'' 344, line 40, for inspection, read impaction. 375, col. 2, note, for " tarsor," read " tensor." 376, col. 2, Bibliography, insert Berres. 483, col. 2, line 25 from bottom, for " fluid," read " blind." 587, col. 1, line 24 from bottom, for 45$, read 31^. 587, col. 1, line 22 from bottom, 'for 41 J, read 28|. 587, col. 1, line 20 from bottom, 'for 54|-f, read 32§}. 587, col. 1, line 18 from bottom, for 48|, read 30^. 598, col. 2, line 11 from bottom, for " The nerves can be traced," read "The nerves have not been traced." 608, col. 2, note, for " Prinella," read " Prunelle." 617, col. 1, line 32 from bottom, for " Enman," read " Erman." 849, col. 2, line 5, for pecuniary, reid visceral. In the article Heart, , for fig. £72, in references, read fig. 274, passim and vice versa. MARCIIANT, PRIMTEK, I N G RAM-CO U RT, FENCHURCH-STREET. *