609€ 66Er0 LOZL¢ DTM AN a “— %. a al Se © nap tee ty Digitized by the Internet Archive in 2007 with funding from Microsoft Corporation http://www.archive.org/details/cyclopaediaofana02londuoft THE CYCLOPAZDIA ANATOMY anno PHYSIOLOGY. VOL. II. THE CYCLOPADIA OF ANATOMY ann PHYSIOLOGY. EDITED BY ROBERT B. TODD, M.D. F.RS. FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS; PROFESSOR OF PHYSIOLOGY AND OF GENERAL AND MORBID ANATOMY IN KING'S COLLEGE, LONDON, ETC. ETC. LONDON: SHERWOOD, GILBERT, AND PIPER, PATERNOSTER-ROW. 1839. baal an ee Ek 3 Ph 4» P ae oe ‘ ; Fi lf CONTRIBUTORS. ROBERT ADAMS, Ese. rgeon to the Richmond Hospital, and Lecturer on Porat K, MB. Dubin, Weer. ALISON M.D. F.R.S.E. Professor of a institutes of Medicine in the Univer- ror al KNDE JOUN ANDERSON, Esa. M.E.S. Richmond. I ABIONN, M.D. M. R.LA. f. of Chem. to the Royal Coll.’of Surgeons, Ireland. VICTOR AUDOUI ‘aris. Professeur-Administrateur an Musee d’ Histoire Naturelle. B. G. BABINGTON, M.D. F.R.S. THOMAS BELL, F.R.S. Professor of Zoology in Kin, Dt TA CHARLES BENSON, MLD Prof, of Med. to the at Col, of oo = JOHN BOSTOCK, M.D. V.P.R.S. London. W. BOWMAN, Esq. Demonstrator of ie ae King’s College, London, W.T. BRAND R.S. Professor of Chemis J. E. BRENA N, G. BRESCHET, M.D. Surgeon to the Hotel-Dieu, Paris. Ww. al CARPENTER, Ese. . on Forensic Med. at the Bristol Med. Sch., &c. JOUN COLDSTREAM, M.D. Leith. painbeeh gt gc py eaeerton Natural History Society of DAVID ¢ CRAIGIE, M.D. F.R.S.E. Fellow of the RoyalColle of — T. BLIZARD CURLING Assistant Surgeon to the ek alae and Lec- turer on Morbid Anatomy. G. P. DESHAYES, M.D. Paris. A. T.S. DODD, Ese. Surgeon to the Infirmary, kanes and late Demon- of Anatomy at Guy’s Hospital, H. DUTROCHET, M.D Member of the beads of France, Paris. W.F. EDWARDS, M.D. F.RS. Member of the Institute of France, Paris. H. MILNE EDWARDS, M.D Professor of Natural Histo to the College of Henry le and a3 oa Central School of Arts and Manu- ARTHUR FARRE, MB. F.RS. Physician to the Gen. Disp., and Lect. on Forensic Med. and ees Anat. and Physiol. at St. Bartholo- mew’s GRAIN R. D. GRAINGER, Esa. Lecturer on Anatomy and Physiology at the Webb- Street School of Anatomy. .G T, M.D. F.RS. L.& E. ite the Royal Institution, &c. hy te of cope al College of Physicians, Edinburgh, Ppl bl Anatomy and Zoology in University Ce Colles MARSHALL HALL, M.D. F.RS. L. & E. London HENRY. HANCOCK, Esq. Danni on — ans Physiology at, and Surgeon to the a ROBERT fi TARRISON, M.D. M.R.LA. and Surg. in t TAY of Dublin, souiN’ iiAiet, oe Me" M.I.A, of Anat, ii al — of Sur. EM: ISD. ‘GEOFFROY St. HILAIR Member of the ‘On M of Do'M —— ARTHUR JACOB, M M.R.I. ss fa tanaae of Anatom: ana oe to the Royal of Surgeons in Ireland TR RYMER JONES, Esa. Prof. of Comp. Anat,, in King’s College, London. T. WHARTON JONES, Ese. London. F. KIERNAN, F.R.S. London. T. WILKINSON KING, Esa. Lect. on Comp. Anat. and a Phys at Guy's Hospital. SAMUEL LANE, Es ti A 55% G "s Hospital, London. FT. Sree oa: et ee JOHN MALYN, Esq. Su m to thi We it W. F. MONTGOMERY, M.D. M.R.LA, Fellow and Professor of Midwife to the King and ueen’s oN e of Physicians in Ireland. GEORGE NEW PORT, Ese. Vice-Pres. of the Entomological Society of London. R. OWEN, F.IS. F.GS. tive A y and Physiology to the Royal Colles e of Surgeons in prefey RICHARD ARTRIDGE, F.R.S. poipess of Descriptive and Surgical Anat. in King’s Coll, BENJAMIN PHILLIPS, F.R.S. London. Surgeon to the Marylebone Infirmary, W.H. PORTER, Ese. Prof. of Surgery th) the ACD Coll. of Surg. in Ireland. J.C. PRICHAR . F.RS. Corresponding alt eis the Institute of France, Member of the Royal Academy of Medicine of Paris, and Senior Physician to the Bristol Infirmary. G. O. REES, M.D. Lond ndaon. J. REID, M.D. Edinburgh. Fellow of the Royal College of Physicians in Edin- burgh, and Lecturer on the Institutes re ne. EDWARD RIGBY, M.D. F.L Lect. on Midwifery at St. Bartholomew's Hos OS J. FORBES ROYLE, M.D. V.P.RS. Professor of Materia Medica in King’s College, oc HENRY SEARLE, Ese. London. E. os A. SERRES, M.D. sician to the Hos ital of t Pitie, &c. Ke. Paris, . SHARPEY, M.D. F.RS.E. Prof. of Anat. ‘and Par’ in Univ. Col. London. JOHN SIMON, Ese. Demonstrator of anaiom in King’s College, London. J. Y. SIMPSON, rele od Me hy yal cole of Physicians, Edinburgh, SAMUEL SOLLY, F.R.S. GABRIEL STOKES, M.D. Surgeon to the South Eustern Dispensary, and Demon- strator of Anatomy in the Park-street Sc ool of Medi- cine, Dublin. J.A. SYMONDS, M.D. Physician to the Bristol General ey ital and Dis: sary, and Lecturer on the Theory and Practice of cine at the Bristol Medical School. ALLEN THOMSON, M.D. Fellow of the Royal College of Surgeons, and Lecturer on the Institutions of Medicine, Edinburgh. RUDOLPH WAGNER, M.D. Professor of Medicine and “of Comparative Anatomy in the Royal University, Erlangen. C. WHEATSTONE, 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 tg and Practice of Medicine in the Aldersgate-street Sc! W. J. ERASMUS W VILSON, Esa. Lecturer on Anat.and Physiol. in sy denham Coll Lon.; and Consulting Surgeon to the St, Pancras Infirmary. W. YARRELL, F.LS, F.Z.S. edi- SVT AE é hg ¢ ee he) Ls 8 " + Pt a i’ i% Wiel ; ‘ P Se } ae q ” 7) j ous + we i Re rn i id \ Fl, ~~ , - Foot, Bones and Diaphragm.......... Dr. Benson ...... 1 Digestion Dr. Bostock Digestive Canal...... Dr. Grant Echinodermata .....- Dr. Sharpey ...... 30 Edentata ....+++++. 7. Bell, Esq... Elasticity ........+. Dr. Brenan ...... Elbow, Region of the Dr. Hart .......- Elbow, Joint of, Normal Ahetomy tr. Hart ..eseeee Elbow, Joint of, Ab- Paidek Anatomy * Vk Adams, Esq. .. Electricity, Animal .. Endosmosis Entozoa ..cccosesses - Erectile Tissue ...... Excretion ..secccees Extremity ......000 Eye sccccccvccccsees Face veccccescevoes Fascia ......0+.. «++ Dr. Todd...... Fat .cceccecesccseee W.T. Brande, Esq. Femoral Artery...... Dr. Alcock «++... ‘Pibrine .........5.. W.T. Brande, Esq. Pibro-Cartilage ...... Dr. Todd .. Fibrous Tissue ...... R.D.Grainger, Esq. Fibular Artery ...... Dre Todd .sssesee Fifth Pair of Nerves.. Dr. Alcock ...... Foetus.............. Dr. Montgomery... weeeceeeee BAT. PO8TOCK se eens Dr. Coldstream .. Dr. Dutrochet .... R. Owen, Esq... Dr. Hart .ccvccee Dr. Alison ..++++ Dr. Todd's ccvcses Dr. Jacob. ....00 R. Partridge, Esq. - Relate of ook is. x. tr. Todd sovcccee Foot, Abnormal Con- ditions of ........ Foot, Regions and Muscles of .....+ Fore-arm, Muscles sa ievaicnn ae Is Solly, Esq. «++. Fourth Pair of Nerves Dr. Alcock ...... Ganglion.........+.. R.D.Grainger, Esq. Gasteropoda ...... 7. Rymer Jones, Esq. ba. T. 8. Dodd, Esq. } 4.7. 8, Dodd, Esq. CONTENTS OF THE SECOND VOLUME. Page Gelatin << siscis veas< W. T. Drande, Esq. 404 sip sisi OrBanS br. Rymer Jones, Esq. 406 Generation........ Dr. Allen Thomson.. 424 Gland .cccccccses. R. D. Grainger, Esq. 480 Chaat } Dr. Reidss..see+es 494 Nerve. secssees Glutwal Region.... A.T. S. Dodd, Esq. 500 Groin, Region of the Dr, Todd ........+. 503 Hamatosine ...... Dr. Rees ......0+. - 503 Hand, Bones of the Dr. Todd .....-++++ 505 Hand, Abnormal Conditions of the Fe. Ane ENG: eae Had, Muscles of F. T. M‘ Dougall, Esq. 519 the cccocceees Hand, Regions ofthe F. T. M‘ Dougall, Esq. 523 Hearing, Organ of.. T. W. Jones, Esq... 529 Hearing .......0.+ Dr. Todd ....20- ++. 564 Heart ..cccccsesse Dre Reid scccccccse 597 Heart, on the 2 Arrangement of ¢ H. Searle, Esq. .... 619 the Fibres of the) Heart, Abnormal Cénditiogs of the , Dr, Todd .os....0 + 630 Heat, Animal...... Dr. W. F. Edwards . 648 Hermaphroditism .. Dr. Simpson........ 684 Hernia.....+...... W. H. Porter, Esq. 738 Hibernation ...... Dr. Marshall Hall .. 764 at re ia. Hancock, Esq. .. 776 Hip-Joint, Abnor- salConditions of } R. Adams, Esq. .... 780 Hyperemia ...... Dr. Todd .........2 825 Hypertrophy ...... Dr. Todd ......+0++ 826 Iliac Arteries...... Dr. Alcock ....... + 827 Innominata Artery . H. Hancock, Esq. .. 850 Insecta ..... esses G. Newport, Esq. .. 853 994 Insectivora.....++. UT, Bell, Esq. sues - a a a THE CYCLOPHZDIA OF ANATOMY AND PHYSIOLOGY. DIAPHRAGM (in anatomy), OraPecrr uae dsc, inter, and Pgacow, sepio, claudo ; Lat. dia- phragma ; Vtal. diaframma; Fr. diaphragme ; 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 ean be detected in the Invertebrate classes of animals; the function of which it is a princi- Et muscularagentin the Mammalia, respiration, ing effected by the skin, intestines, stigmata, trachee, gills, &c. Most of the Vertebrata, however, exhibit something analogous to the diaph - 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 pees 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 develo in the parrot.* But, as has been said, it is only in Mammalia that the genuine diaph 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. Il. 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.t 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. : Diapuracm (human anatomy).—The dia- phragm in man is a muscle of great importance (post cor facile princeps, Haller), being the chief agent by which sis 0 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. Carus, Comparative Anatomy. + Tyson, ¢ Cuvier, Anat, Comp. vol.:-iy. 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, ist, the form, structure, and organization of the diaphragm ; 2nd, its uses; and, 3rd, its malformations and diseases. Thoracic surface seen Srom before. 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 ©. The centre is tendinous; the border consists of fleshy fibres. The tendinous part (fig. 1, T) (centrum tendineum, s. nerveum, 8. phrenicum, cordiform 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 tight 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 whi 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. Itis less curved than the fleshy portion, and more fixed in its position. One large opening ae 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 im order, bounding these spaces externally, are much longer; they pass outwards and down- wards to the seventh rib, and are inserted by a =!" = DIAPHRAGM. 3 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- . 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.* ( Fig.1, d.) This last appel- lation is bestowed ona thin aponeurosis which stretches from the inferior margin of the last rib to the point of the transverse 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 + (fig. 1,J;) it is also called the true, and the external the /a/se,—names derived from their structure. The vertebral oy smaller — of _ dia- lhragm is placed almost perpendicularly. The bres pass off from the nero sine 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 e arcuatum ; but greater number form two large and long fasciculi, the crura, or pillars, or pe of the by ea é 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- tebre 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 p are the cordiform tendon, separate imme- iately from each other, to permit the cesopha- gus to pass into the abdomen, and unite again ind that tube. Here a crossing or inter- lacing of the fibres takes place, a considerable bundle descending from the left side of the * Arcus tendineus exterior, Senac, -¢ Arcus tendineus interior, Id. esophagus 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 (fig.1,c). It corre- sponds to the line of division between the middle and right lobes. Its shape is quadrangular, (foramen quadratum,) having an anterior, apos- terior, a right and a left edge. The rightis 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. e 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 esophagus and pneumogastric nerves pass (_ Sig. 1,e). Its majoraxis, 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 Gaul 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 B2 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 crus, 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 pleure 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, cand 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 — economy as the diaphragm, and 80 perpetually in action, requires a large suppl of blood, This it Saas: ecdel warms 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 vene 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 /umbar send twigs to the crura, the Jower 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 the 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 DIAPHRAGM, 5 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 tang 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 Sadoagh 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: déscent 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 csophageal orifice, and contracting in concert with the rest of the muscle, close that opening, and thus prevent pepueyietion 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 ale do not un- dergo much alteration. Haller indeed says that he saw the diaphragm descend so much in violent inspiration as to sans a convexity to- wards the abdomen.t 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- ible on account of its attachments. We nd on some occasions oe pee. of the dia- phragm act independently of the other. The secowiance of the diaphragm in respira- tion is shewn by the difficulty with which that ’ * Senac says the anterior fibres assist in expira- tion by drawing the ribs inwards and backwards. Acad. des Sciences, 1729. + In violentissima respiratione omnino vidi deor- sum versus abdomen diaphragma convexum reddi, Haller, Elem, Phys. lib, viii. sect. 1, function is performed when the actions of the niuscle 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 dyspnea 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 be airs 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 eave being at the same time produced in the arynx. e diaphragm also performs an important part in vomiting. A full inspiration precedes this act, then the glottis is closed, on the ub- * Senac. P 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 aliving 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 cayities 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 esophageal 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,+ 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- = of the total absence of the diaphragm was issected by Diemorbroeck. The subject lived to the age of seven years without suffering any inconvenience except a frequent cough.t 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 vers. 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. + The word phrenic, used with reference to the diaphragm, as phrenic nerve, phrenic centre, &c. has its origin in this opinion, Ppeves, A dpuy, mens, tanquam mentis sedes. $ Dict. des Sciences Méd,-art, Diaphragme. rudimentary. It sometimes happens that the natural openings of the diaphragm are too large, and then protrusions or herniz are apt to occur by the sides of the tubes which they were intended alone to transmit. Openings frequently occur in consequence of disease or violence. Ulcers often make a perforation, and it is common enough to see an abscess of the liver make its way into the lung through the diaphragm. The writer lately saw an abscess, which formed in the gastrosplenic omentum, take the same course. Wounds often penetrate the diaphragm, and it is remarkable that however small they may be, a ventral phrenic hernia is sure to follow. The diaphragm has been suddenly ruptured during violent muscular efforts, vomiting, falls, &c. and instant death has usually followed. Various examples of such ruptures are recorded in the Dictionnaire des Sciences Méd. art, Diaphragme. The countenance in all such cases assumes the peculiar expression or grin called risus Sardonicus. The diaphragm is subject to attacks of in- flammation, which, in almost every case, is communicated to it by the adhering pleura or peritoneum, It is indeed usually confined to one or other of these serous membranes, chiefly the pleura, and does not affect the muscular fibre. Itis, notwithstanding, termed diaphrag- mitis. Wippocrates called it phrenitis, and Boerhaave neue the name to paraphrenitis, to distinguish it from a well-known cerebral affection. Gangrene, collections of pus, tumours, &c. are occasionally met with, and are of very difficult diagnosis. Cartilaginous and osseous deposits have been found on both sides of the diaphragm in the subserous cellular tissue. The diaphragm is often considerably dis- placed upwards or downwards. In ascites, and in consequence of diseases of the liver and of abdominal tumours, it may be pushed up to the second rib on one side; in thoracic affee- tions again it has been so pushed down as to become convex, in part of its extent, towards the abdomen. Senac mentions a case of great enlargement of the heart which caused the cen- tral tendon to be buried in the abdomen, it being formed into a kind of pouch.* Dr. W. Stokes found the left ala convex towards the abdomen in emphysema of the lungs,t and it is known to yield extensively to the pressure of fluid in cases of empyema, more especially if the pleura covering it has been much engaged, as the same accurate observer has noticed and explained. For BIBLIOGRAPHY see that of Anatomy (INTRO- DUCTION), (Charles Benson.) . DIGESTION, (Fr. digestion; Germ. Ver- dauung ; Ital. digestione.) This term is em- ployed in Physiology to designate that func- tion by which alimentary matter is received * Acad. des Sciences, Mem. 1729. + Dublin Med. Journal, vol. ix. p. 37. DIGESTION. 7 into an appropriate organ, or set of organs, and whet ie 5 subjected to a specific action, which adapts it for the purpose of nutrition.” In its original and technical sense this action was confined to the stomach,t but it is gene- rally applied more extensively, so as to include a number of distinct operations, and a suc- cession of changes, which the food experiences, eae it has been received into the oy until a portion of its elements are separat from the mass, and are conveyed, by ce te of the lacteals, to the iccdvandele In the following article we shall employ the term in its most extensive acceptation, and shall regard the whole as one function, the successive steps of which are intimately and necessarily connected together, and each of them essential to the completion of the whole.t We shall commence by a description of the organs of digestion, we shall next give an ac- count of the nature of the substances usually employed as food ; in the third place we shall trace the successive changes which the food iences in the different parts of the pro- cess; in the fourth place we shall examine some of the hypotheses that have been pro- posed to explain these various operations, and shall conclude by some remarks on certain affections of the digestive organs, which are connected with, or dependant upon, their functions. I. Description of the organs of digestion. — The organs of digestion, taken in their most comprehensive sense, may be arranged under three divisions: the first, by which the aliment is prepared for the chemical change which it is afterwards to experience, and is conveyed into the stomach, being principally of a mechanical nature; secondly, what have been more ex- clusively termed the proper digestive organs, where the aliment receives its appropriate chemical changes; and lastly, those organs a which, after the nutritive substance thus elaborated has been separated from the mass, in order to be conveyed into the blood, the residuary matter is expelled from he system.§ * The term appears to have been originally bor- rowed from the chemists, or the chemical physio- logists, who supposed that the aliment was ma- cerated in the stomach precisely in the same manner as substances are said to be digested in i perations in the lab y- It was aterm very frequently employed by Van Helmont.—See Castelli, Lexicon, ‘* Digestio.” + Cullen’s Physiol. § 201. $¢ Magendie divides the teasers of digestion into eight distinct actions: 1, the reception of the food; 2, mastication; 3, insalivation ; 4, deglutition; 5, the action of the stomach; 6, of the smaller in- testines; 7, of the large intestines; 8, expulsion of the feces. Phys. t. ii. p. 33. Adelon and Chaussier arrange them under seven heads: appe- tition, gustation, mastication, deglution, chymitica- tion, chylification, and defecation. Dict. Sc. Méd. t. ix. p. 357. § Adelon considers the digestive organs to con- sist of six essential parts: the ey the pharynx h, the In the higher orders of animals, where the functions are more numerous, and more varied. in their nature, we find them to be so inti- mately connected together, and dependent on each other, that it is impossible any one of them to be suspended without the derange- ment of the whole. But as we descend to animals of a less perfect and complicated structure, the functions are considerably re- duced in number, and seem also to be less intimately connected, so that certain of them are either altogether wanting, or are performed, although imperfectly, by other organs, which are not exclusively appropriated to them. Thus we observe that some, even of the which are the most essential to human ex- istence, as the brain, the heart, and the lungs, are not to be found in many very extensive classes of animals, some of the functions be- longing to these organs being entirely deficient, or being effected in a more simple or a less complete manner, by a less complicated a paratus. As we descend still lower in the scale, we find the functions still more restricted and simplified, until we arrive at the lowest term which would appear to be compatible with the existence of an organized being, where no functions remain but those which seem to be essential to the original formation of the animal and to its subsequent nutrition. That some apparatus of this description is abso- lutely essential may be concluded, both from the consideration, that the nutritive matter which is received into the system must un- dergo a certain change, either chemical or mechanical, before it can be employed for this purpose, as well as from the fact, that a sto- mach, or something equivalent to it, has been found to be the circumstance, which is the most characteristic of animal, as distinguished from vegetable life.* Accordingly, with a very few exceptions, and those perhaps depending rather upon the inaccuracy of our observation, than upon the actual fact, it is generally ad- mitted, that every animal, the size and texture of which admit of its being distinctly ex- amined, is possessed of some organ appro- priated to the purposes of digestion.+ Of the three orders of parts mentioned above, the second is the only indispensable one, or that which is alone essential to the due per- formance of the function. In many cases the aliment is directly received into the stomach, without any previous preparation, either che- mical or mechanical, and there are not a few instances in which the residuary matter is im- mediately rejected from the stomach, without any distinct apparatus for its removal. In the * Smith’s Introd. to Botany, p. 5; Grant, Cyc. of Anat. v.i. p. 107. Dr. Willis, on the other hand, remarks, in the same work, that nothing resembling a stomach has been fonnd in any vege- table, p- 107. + Semmering, Corp. hum. fab. t. vi. p. 229; Blumenbach’s Comp. Anat. § 82. Many of the exceptions which were supposed to exist to the and phagus, the cd , the small intestines, and the large intestines, Dict. Sc, Méd. t. ix. p.355, g 1 rule have been removed by the interesting observations of Ehrenberg; Ann. Sc, Nat, t. ii. 2e sér.; Roget’s Bridgewater Treatise, v. ii. p. 95. 8 DIGESTION. following pages our main object will be to give an account of the function of digestion as it is exercised in man and in those animals which the most nearly resemble him, referring to other animals only so far as it may contribute to illustrate or explain the nature of the ope- ration in the human species. : In the various divisions of the Mammalia the first order of parts may be arranged under the five heads of the mouth iver its mye appendages, the teeth, the salivary glands, the | stares, snd the cngtagye.. With the exception of the salivary glands, the effect of these organs is entirely mechanical ; it con- sists in the prehension, the mastication, and the deglutition of the aliment. The first of these organs may be again subdivided into three , the lips, the cheeks, and the tongue; the lips being more immediately adapted for seizing and retaining the food, and the others for conveying it, in the first instance, to the teeth, for the pare of mas- tication, and afterwards to the pharynx, in order that it may be swallowed. In this, as in eyery other part of the animal frame, we perceive that adaptation of the structure of each individual organ to the general habits of the animal, which forms a constant subject of delight and admiration to the anatomist and the physiologist. In animals that feed upon succulent and luxuriant herbage the lips are capacious, strong, and pendulous, for the pur- pose of grasping and detaching their food, while in those that employ an animal diet, where their prey is to be seized and divided principally by means of the teeth, the lips are thin, membranous, and retractile. Again in the muscles that are connected with the cheeks, we find the same adaptation, although perhaps not in so obvious a degree. We observe that animals who receive large quantities of food, either in consequence of its being of a less nutritive nature, or from any other peculiarity in their habits and organization, as well as those whose food is of a harder consistence and firmer texture, have larger and: more powerful muscles, both for the purpose of moving the jaws with greater force, and for acting upon the larger mass of matter which is taken into the mouth. The principle of adaptation is still more remarkable in the teeth. Among the different orders which compose the Mammalia, we ob-~ serve a general analogy and resemblance be- tween the teeth, both as to their number, form, and relative position, while, at the same time, there is so great a diversity in the different tribes of animals, that some of the most dis- tinguished naturalists have regarded these organs as the parts the best adapted for form- ‘ing the basis of their systematic arrangements, inasmuch as they afford the most characteristic marks of the habits of the animals, and of the Ee of their other functions.* Thus, y an inspection of the teeth we can at once discover whether the individual is intended to * Linneus, Sys. Nat. t. i, p- 16 et alibi; Shaw’s Zool. v. i. Introd. Pp. vii 3 et alibi. employ animal or vegetable food, some of them being obviously adapted for seizing and lace- rating the animals which they acquire in the chace or by combat, while the teeth of others are obviously formed for the cropping of vege- tables, and for breaking down and triturating the tough and rigid parts of which they prin- cipally consist. It is with a view to this dou- ble purpose of prehension and mastication that the great division of the teeth into the incisors and the molares, the cutting and the grinding teeth, depends, the former being of course situated in the front of the mouth, the latter in the sides of the jaws. The chemical com- position and mechanical texture of the teeth is no less adapted to their office of dividing and comminuting the food than their figure and position. They are composed of nearly the same materials with the bones generally, but their texture is considerably more dense and compact, while they are covered with an ena-~ mel of so peculiarly firm a consistence, as to enable them, in many kinds of animals, to break down and pulverize even the hardest bones of other animals, and to reduce them to a state in which they may be swallowed, and received by the stomach, in the condition the best adapted for being acted upon by the gastric juice.* At the same time that the alimentary matter is subjected to the mechanical action of the teeth, it is mixed with the fluids that are dis- charged from the salivary and mucous glands, which are situated in various parts of the mouth. The use of the saliva is to soften the food, and thus render it more easily masti- cated, to facilitate its passage along the pha- rynx and esophagus, and perhaps, by a certain chemical action, to prepare it for the change which it is afterwards to experience, when it is received into the stomach.+ The food, after it has been sufficiently di- vided by the teeth, and incorporated with the saliva, is transmitted, by the act of deglutition, into the stomach. There is perhaps no part of the system, which exhibits a more perfect specimen of animal mechanism than the pro- cess of deglutition. It consists in the sueces- sive contraction of various muscles, that are connected with the contiguous parts, each of which contributes to form aseries of mecha-— nical actions, which, when connected with each other, effect the ultimate object in the most complete manner. The muscles of the mouth and the tongue first mould the mas- ticated aliment into the proper form, and trans- mit it to the pharynx; this partis, at the same time, by the cooperation of other muscles, placed in the most suitable position for re- ceiving the alimentary mass, and transmitting it to the esophagus, while another set of mus- * Hatchett, in Phil. Trans, for 1799, p. 328-9 ; Berzelius, View of Animal Chemistry, p. 78; Pepys, in Fox on the Teeth, p- 92 et seq; Turner’s Chemistry, p. 1012. t For the opinions that were entertained by the older physiologists on this point the reader is re- ferred to Baglivi, Diss. 2, circa salivam, op. p- 412 et seq.; also to Haller, El, Phys, 18, 2. is. ———— DIGESTION. 9 cles causes the epiglottis to close the passage into the larynx. The muscular fibres of the esophagus itself are now brought into play, andy their successive contraction, propel the food from the upper to the lower part of the tube, and thus convey it to its final destination. three stages, which altogether constitute a very complicated train of actions, are so connected with each other, that the operation appears to be of the most simple kind; it is one of the first that is performed by the newly born animal, and is exercised during the whole ait of existence with the most perfect ility.* The food, after having thus experienced the action of the first order of parts, which, as we have seen above, is principally, if not entirely, of a mechanical nature, is finally deposited in the stomach. The stomach is a bag of an irregular oval form, which lies obliquely across the upper part of the abdomen, in what is termed, from the presence of this organ, the epigastric apgon. The structure of the sto- mach, considered in its physiological relation, is threefold. A large portion of it is composed of membranous matter, which gives it its ge- neral form, determines its bulk, and connects it with the neighbouring parts, constituting its external coat. To the interior surface of this coat are attached a number vf muscular fibres, by which the various contractile actions of the stomach are performed; these, although not capable of being exhibited as a connected or continuous structure, are considered, accord- ing to the custom of the anatomists, as com- posing the muscular coat, while its internal coat consists of a mucous membrane, which appears to be the immediate seat of the se- ereting glands, from which the stomach de- tives its appropriate Huids. But besides this, which may be regarded as the physiological structure of the stomach, by which its are so arranged as to give the organ its form and ition, its contractile power, and its chemical action, the anatomists have resolved it intoa eee number of mechanical divisions, depending principally upon the minuteness to which they have carried their dissections. In this way no less than six or even eight distinct Strata or coats have been assigned to the sto- mach. First, the peritoneal covering, which it has in common with all the other abdominal viscera, the dense membrane which more especially gives the stomach its form, called in the language of the older writers the ner- vous coat, two muscular coats,+ one composed of longitudinal and the other of circular fibres, and the innermost, or, as it has been termed, * Fora it of the of deglu- tition generally we may refer to Boerhaave, Prel, t. i, $70..2, Haller’s Phys. by Mihles, lect. 23; Lin. cap. 18, § 607.. 621; El. Phys. xviii. 3, 21..5; Dumas, Physiol. t. i. p. 341. 353, who divides the act of deglutition into four stages, and to Magendie, Physiol. t. ii. p. 54.. 67, who reduces moe — + Boyer, ubi supra, supposes that the muscular fibres are babies gs in three layers, See also El- liotson’s Physiol. p. 78. the villous coat, together with three cellular coats, which are situated between the former and connect them with each other. The ner- vous coat is usually described as being the seat of the glands, as well as of the bloodvessels, nerves, and absorbents which belong to the stomach; but although they cannot perhaps be actually traced beyond this , there is some reason to suppose that their ultimate destination is on the innermost or villous coat. The membranous part of the stomach a pears to be peculiarly distensible, so as reaidily to admit of having its capacity greatly and suddenly increased, in order to contain the large quantity of solids and fluids that are occasionally received into it, while its mus- cular fibres and nerves are possessed respec- tively of a high degree of contractility and sensibility, by which they act powerfully on its contents, propelling them, when necessary, into the duodenum, and thus reducing the bulk of the stomach to its ordinary standard. Besides the mucous fluid which the inner sur- face secretes, in common with all other mem- branes of this description, the stomach is su posed to possess certain glands, adapted for the formation of a specific fluid, termed the gastric juice, which acts an important part in the process of digestion ; but the presence of these glands has been rather inferred from their supposed necessity, than from any actual ob- servation of their existence.* From the peculiar form aud disposition of what have been termed the muscular coats of the stomach, they not only enable the organ to contract in its whole extent and in all direc- tions, but they give to its individual parts the power of successively contracting and relaxing, so as to produce what has been termed its peristaltic or vermicular motion.+ The effect produced appears to be, in»the first instance, to form in the interior of the stomach a series of folds or furrows, and at the same time to agitate the alimentary mass, so as to bring every part of it, in its turn, within the in- fluence of the gastric juice, while the whole of the mass is gradually carried forwards to- wards the pylorus, and is in due time dis- charged from that orifice. The muscular fibres of the stomach, like all those that are con- nected with membranous expansions, forming what are termed muscular coats, are not under the control of the will. In consequence of the great degree of vitality which the stomach possesses, a circumstance in which it is surpassed by scarcely any organ in the whole body, it is very plentifully provided with bloodvessels and with nerves. The arteries, according to the ordinary construction of the sys- tem, are furnished by the contiguous large trunks, * Winslow's Anat. Sect. viii. § 63..5 ; Haller, El. Phys. xix. 1. 14; Bell’s Anat. v. iv. p. 58. + Haller, El. Phys. xix. 4. 9,0; Rosas Anat. t.iy. p.333..5; Bertin, Mém. Acad. pour 1760, p- 58 et seq.; this writer appears to have been one of the first who yave us a correct description of the muscular coats of the stomach, ‘~ DIGESTION. whilethe veins, incommon with all those that be- long to what are termed the chylopoietic viscera, terminate in the vena porte.* The nerves of the stomach are not only very numerous, but they are remarkable for the number of different sources whence they derive their origin. These are, in the first instance, threefold ; it is fur- nished with a large quantity of ganglionic nerves, in common with all the neighbouring viscera; it likewise receives nerves directly from the spinal cord, and unlike all the other parts of the body, except what are termed the organs of sense, it has a pair of cerebral nerves in a great degree appropriated to it. The specific uses of these different nerves are not certainly ascertained, and it would scarcely fall under the immediate object of this treatise to enter upon the consideration of this point; but we may observe, that no organ, in any part of the body, partakes more fully of what may be considered as the actions of the nervous system, or is more remarkably affected by its various changes, including not merely those of a physio- logical nature, but such likewise as are con- nected with the various mental impressions.+ The two extremities of the stomach, by which the food is received and discharged, are ge te tively termed the cardia and the pylorus. Their Structure, in many respects, differs from that of the other parts of the organ. ‘The cardia is remarkable for the great proportion of nerves which are distributed over it, and as these are principally derived from the par vagum, or the eighth pair of cerebral nerves, we may under- stand why this should be the most sensitive pet of the stomach. The pylorus is remarkable r the mechanical disposition of its muscular fibres, which form an imperfect kind of sphinc- ter, by which the food is detained in the cavity until it has experienced the chemical action of the gastric juice. And besides the functions which are actually possessed by this part, many imaginary and mysterious powers were ascribed to the pylorus by the older physiologists. The seniaibitiey of the stomach was supposed to reside more especially in this extremity ; it was selected by some of the visionary philosophers of the sixteenth and seventeenth centuries as being the seat of the soul, and even some of the moderns ascribe to it a kind of intelligence or peculiar tact, by which it is enabled to select the part of the alimentary mass, which has been sufficiently prepared to enter the duodenum, while it prevents the remainder from passing through its orifice, and retains it for the purpose of being still farther elaborated.t On account of the form and position of the stomach it is sufficiently obvious, that a con- siderable proportion of its contents must be, at all times, below the level of the pylorus. The food is hence prevented from passing too hastily out of the organ, while we may conclude that * Winslow, sect. viii, § 2. 72..7; Haller, El. ae xix. }. 16..20; Blumenbach, Inst, Physiol. § 3 Bell’s Dissect. p. 19. . 25. pl. 3, 4. + Winslow, ubi supra, 78, 9; Haller, xix. 1. 21 i Blumenbach, § > Bell’s Anat. v. iv. p. 64; Walter, Tab. nerv. No. 3, 4. t Richerand, Physiol, §23. § 111, 2. the transmission of the food is almost entirely effected by the contraction of its muscular fibres, aided probably by the diaphragm and the abdominal muscles, but scarcely in any degree by the mere action of gravity.* It must, however, be observed that the position of the stomach generally, with respect to theneighbour- ing organs, as well as the relation of its different parts to each other, varies considerably accordi toits state of repletion ; when it is the most fully distended, its large arch, which previously was pendulous, is now pushed forwards and raised upwards, so as to be nearly on the same level with the pylorus. When the food leaves the stomach, it is re- ceived by the intestinal canal, a long and winding tube, which varies much in its diameter and its form, in the different parts of its course, but which, both in its anatomical structure and in its physiological functions, bears a consider- able resemblance to the stomach. It may be said, in the same manner, to consist of three essential parts, the membranous, the muscular, and the mucous, which respectively serve to give it its form, to enable it to propel its con- tents, and to furnish the necessary secretions. With respect to the form of its individual parts, it has been divided, in the first instance, into the large and small intestines, a division which depends upon the comparative diameter of the two portions, while each of these has been sub- divided into three parts, depending more upon their form and their position than upon their structure or functions. But although it may be supposed, that the division of the tube into the great and small in- testines refers to their difference of size alone, it is to be observed that they perform very differ- ent functions, and are subservient to very differ- ent purposes in the animal economy. It is in the small intestines, and more especially in the first portion of them, termed the duodenum, that what must be considered as the most essen- tial or specific part of the function of digestion is effected, the formation of chyle, while it is almost exclusively in the duodenum and the other small intestines, the jejunum and the ileum, that the chyle thus produced is taken up by the lacteals, in order to be conveyed to the thoracic duct, and finally deposited in the bloodvessels. The use of the large intestines, and more es pecially of the colon, which constitutes a con- siderable proportion of the whole, appears to be more of a mechanical nature, serving as a depo- sit or reservoir, in which the residuary matter is received and lodged, fora certain period, until it is finally expelled from the system. The division between the parts of the small intestines, to which the names jejunum and ileum have been applied, is entirely arbitrary, as they ap- pear to be precisely similar to each other, both in their structure and their functions. But the case is very different with respect to the duode- num, which in both these respects possesses a clearly marked and distinctive character. Of * Haller, ubi supra, § 2. .4, t Blumenbach, $ 353. Ye a ¥ at" DIGESTION. this anatomists have long been well aware, and it has accordingly been made the object of par- ticular attention, and has even received the ap- Ilation of the accessory stomach ; but we shall enter more particularly into the consideration of this subject when we come to treat upon the difference between chyme and chyle, and the nature of the process by which it is effected. The peculiarities of the digestive organs in the different classes of animals are interesting, not merely as affording remarkable examples of the adaptation of the animal to the situation in which it is placed, but are especially worthy of our notice on this occasion, as serving to illus- trate the nature of the operation generally, and the mode in which its various stages are related to each other. The most remarkable examples of this kind are the complicated stomachs of the Tuminant quadrupeds, and the muscular sto- machs of certain classes of birds.* The ruminant animals belong to the class of the mammalia, and are such as feed principally upon the stalks and leaves of plants. The quan- tity of food which they take is very consider- able; it is swallowed, in the first instance, al- most without mastication, and is received into the first stomach, a large cavity, which is termed the venter magnus, panse, or paunch.t The food, after remaining for some time in this sto- mach, for the purpose, as it would appear, of being macerated, is next conveyed into the second stomach, a smaller cavity, the internal coat of which is drawn up into folds that lie in both directions, so as to form a number of an- gular cells, from which circumstance it has received the appellation of reticulum, bonnet, or honeycomb. The reticulum is provided with a number of strong muscular fibres, by which the food is rounded ito the form ofa ball, and is propelled along the esophagus into the mouth. It is now completely masticated, after having been properly prepared for the pro- cess by its previous maceration in the paunch ; this mastication constitutes what has been termed chewing the cud, or rumination. When the food has been sufficiently com- minuted it is again swallowed, but by a pecu- liar mechanism of muscular contraction the into the venter magnus is closed, while an opening is left for it to into the third stomach, termed omasum,, feuillet, or maniplies ; itis smaller than any of the other cavities, and its internal coat is formed into a series of strong ridges and furrows, but without the transverse < of the reticulum. From the omasum the is finally deposited in the fourth stomach, the abomasum, caillette, or reed, a cavity consi- derably saager than either the second or third stomach, although less than the first. It is of an irregular conical form, the base being turned * For an interesting account of the comparative anatomy of the digestive organs we may refer to Carus’s Comparative Anatomy, by Gore, v. ii. p. 72 et seq. We have selected the terms by which each of the four stomachs is usually designated in Latin, French, and English respectively; there are, how- ey various other names which have been applied to them. il to the omasum ; it is lined witha thick mucous or villous coat, which is contracted into ridges or furrows, somewhat in the manner of the oma- sum, and it appears to be that part of the diges- tive ap us which is analogous to the single stomach of the other mammalia, where the ali- ment undergoes the process of chymification, the three first stomachs being intended to macerate and grind it down, in order to prepare it for the action of the gastric juice. (See Ruminantia.) Although we conceive that the operation of the different of this complicated apparatus is pretty well understood, it still remains for us to inquire into the final cause of the arrange- ment, or why the maceration and mastication of the food in certain classes of animals should be effected in a manner so different from what it is in others, which, in their general structure and functions, the most nearly resemblethem. The opinion which was entertained on this subject by the older anatomists, and which may be still regarded as the popalar doctrine, is, that the nature of the food of these animals, and the large quantity of it necessary for their support, requires a greater length of time for its comminution and a greater quantity of the mucous secretions than it could obtain by the ordinary process. But although there may be some foundation for this opinion, the more extended observations of modern naturalists show, that it does not apply in all cases, and that there are so many exce tions to the general rule as to lead us to doubt the truth of the position.* It is to be ob- served, that when animals with ruminant sto- machs take in liquids, the fluid passes immedi- ately into the second stomach, where it is mixed with the aliment after it has been macerated in the venter magnus, and probably moulds it into the proper form, for its return along the esophagus into the mouth. While the young animal is nourished by the mother’s milk, the fluid is conveyed, in the first instance, through the third stomach into the fourth, and it is not until it begins to take solid food, that the proneee of rumination is established. It is ence concluded, that the animal possesses the wer of conveying the food at pleasure either into the first or the third stomach, and of return- ing it from the second into the mouth ;} these, like many other voluntary acts, being of the kind which are termed instinctive. The other kind of stomach which we, referred to above as possessing a peculiar structure, and acting on a different principle from that of the human species, is the muscular stomach of certain classes of birds. Birds are not pro- vided with teeth, or with any apparatus which can directly serve for the process of mastica- tion; yet many of them feed upon hard sub- stances, which cannot be acted upon by the gastric juice, until they have undergone some process, by which they may be comminuted or ground down into a pulpy mass. This is effected by the ingluvies, the craw or crop, and the ventriculus bulbosus or gizzard. e first * Blumenbach’s Comp. Anat. p. 138, note 20. + Home, ubi supra, p. ¢ Blumenbach, ubi supra, p. 138. note 18; Ray’s Wisdom of God, &c., p. 188. 12 of these is a large membranous bag, analogous to the paunch of the ruminants, into which the food, without any previous alteration, is re- ceived from the esophagus, and where it is macerated in the usual manner by the conjoined action of heat and moisture. ; : The gizzard is of much smaller dimensions than the crop, composed of four muscles, two of which are of a flattened form and of very dense texture, lined internally with a firm cal- lous membrane, and capable of an extremely powerful action. These constitute the main part of the parietes, the two other muscles being much smaller, and situated at the extremities, serving, as it would appear, merely to com- plete the cavity.* The gizzard is so connected with the crop, that the food, after due macera- tion, is allowed to pass by small successive portions between the two larger muscles; by their contraction they are moved laterally and obliquely upon each other, so that whatever is laced between them is completely triturated. e force of these muscles, as well as the impenetrability of their investing membrane, is almost inconceivably great, so that, according to the experiments of Spallanzani and others, not only are the hardest kinds of seeds and grains reduced to a perfect pulp, but even pieces of glass, sharp metallic instruments, and paineeal substances, are broken down or flattened, while the part still remains unin- jured.t The action of both the crop and the gizzard must be regarded as at least essentially mechanical, mainly adapted for the purposes of maceration and trituration, and as compen- sating for the saliva and teeth of man and the greatest part of the mammalia. We are able in this case to observe the connexion between the habits of the animals and the peculiarities of their organs more clearly than with regard to the ruminants, for we can always perceive an intimate relation between the food of the different kinds of birds and the structure of their stomach. II. Anaccount of thenatureof the substances usually employed as food.—All the articles that are employed in diet may be arranged under the two primary divisions of animal and vege- table, according to the source whence they are derived. Those in which the distinctive cha- racters are the most strongly marked differ both in their proximate principles and their ultimate elements, although in this, as in most other cases, there are many intermediate shades. The ulti- mate elements of vegetables are oxygen, hy- drogen, and carbon, to which, in some cases, a portion of nitrogen is added. Animal sub- Stances contain all these four ingredients, the carbon being in less quantity than in vege- * Grew, ubi supra, p. 34; Blumenbach, ubi supra, § 99; Peyer, Anat. Ventr. Gall., in Man- get, Bibl. Anat. t. i. p. 172; Hunter on the Ani- mal Economy, p. 198-9; Clift, in Phil. Trans. for 1807, pl. 5, fig. 1 3 Home’s Lect. y. ii. pl. 49, 62; and the art. Aves, t Spallanzani, Dissert. i. §5..8,and10., 22; see also Acad, del Cimento, p- 268,9; Borelli, De motu anim. t. ii. prop. 189; Redi, Esperiense, p. 89 et seq.; Grew, ch. 8; the art. ‘* Birds” in Rees ; and “* Aves” by Mr. Owen, in the present work, DIGESTION. tables, while the hydrogen, and still more the nitrogen, are generally in much greater quan- tity. There are various circumstances which seem to prove that either species of diet is alone competent to the support of life, although each of thats is more especially adapted to certain classes of animals. This, it is pro- bable, depends both upon the chemical and the mechanical nature of the substances in question, but perhaps more upon the latter than the former, for we find that the processes of cookery, which act principally upon mecha- nical principles, render various substances per- fectly digestible, which the stomach could not act upon before they had undergone these operations. We also find that animals, which, in their natural state, have the strongest in- stinctive predilection for certain kinds of food, may, by a gradual training and the n reparation of the articles employed, have their abits entirely changed, without their health being in any degree affected. There is, however, a circumstance in the Structure of the animal, which clearly points out a natural provision for the reception of one species of food in preference to the other, viz. the comparative capacity of the digestive or- gans. It may be concluded that, in all cases, the aliment must undergo a certain change before it can serve for the purpose of nutrition, and that this change will occupy a greater length of time, and that a greater bulk of materials will be requisite, according as the nature of the food received into the stomach is more or less different from the substance into which it is to be afterwards reduced. Hence, as a very general rule, we find that the diges- tive organs of carnivorous animals are less capacious than those of the herbivorous, and that even in the latter there is a considerable difference, according as the food consists of seeds and fruits or of the leaves and stems of plants. There are indeed certain circumstances in the habits of some of the carniyvora which require organs of considerable capacity, as, for ex- ample, those beasts of prey who take their food at long intervals, being supplied, as it were, in an occasional or incidental manner, so that it becomes necessary for them to lay up a considerable store of materials, and to take advantage of any opportunity which presents itself of replenishing the stomach. The anato- mical structure of the human digestive organs indicates that man was intended by nature for a mixed diet of animal and vegetable aliment, but with a preponderance towards the latter ;* and it appears in fact that, while a suitable combination of the two seems the most condu- cive to his health, and to the due ‘ormance of all his functions, either ‘species is alone competent to his growth and nutrition.t * Cuvier, Régne Animal, t. i. p. 86; Lawrence’s Lect. p. 217 et seq.; see also the elaborate dis- Sertation of Richter, De victus animalis antiq. &c. t Haller, El. Phys, xix. 3.2..4; these sections contain a very full account of the different kinds of diet employed by different nations or individuals, We have a number of curious facts of this kind in DIGESTION. - The most important of the proximate prin- ciples employed in diet are Brin, albumen, oil, jelly, gluten, mucilage, farina, and sugar, to which may be added some others of less frequent occurrence. They are derived, more or less, from almost all the classes of animals and vegetables, and from nearly all their indi- vidual parts, their employment being regulated, in most cases, rather by the facility with which theyare procured, and reduced into a form proper to be acted upon by the stomach, than by the quantity of nutritive matter which they con- tain. is is one of those subjects in which we have to notice the remarkable effects of habit and custom, both on the functions and the sensations. We find whole tribes of people living on a diet, which, to those unaccustomed to it, would be not only in the highest degree unpalatable, but likewise altogether indiges- tible; while, by the various modes of preparing food, which have been suggested, either by luxury or by necessity, the most intractable substances are reduced into a digestible state.* The writers on dietetics have attempted to include all substances that are competent to afford nutrition under a few general principles, of which, as they exist in nature, they are supposed to be composed. Cullen, who may be considered as the first who attempted to in- troduce correct philosophical principles into this department of physiology, reduced them to two, the oily and the saccharine, and endea- voured to prove that all the animal fluids may be refe to these principles:+ Magendie, on the contrary, proceeding less upon their chemical composition than upon the forms under which they present themselves, classes alimentary substances under the nine heads of farinaceous, mucilaginous, saccharine, acidu- lous, oily, caseous, gelatinous, albuminous, and fibrinous.{ Dr. Prout, whose views on this subject are marked by his characteristic acuteness, reverts to the mode of Cullen, ad- mitting only of the oily, the saccharine, and the 1 ioe a rinciples, which three, he conceives, form the * groundwork of all orga- nized bodies.”§ Of animal compounds which are employed Stark’s works, p. 94,5; see also Lorry, Sur les ali- mens; Plenk, Bromatologia; Scommering, AY hum. fab. p. 241, 250; Richerand, El. P ys-§ iy p. 83; Parr’s Dict. art. Aliment; Pearson’s Syn- opsis, parti, ; Lawrence’s Lect. p. 201,9; Thack- rah’s Ba Lect. on Diet, p. 54 et seq.; Paris Roget’s Bridgewater Treatise, part 2, , §l. es — Physiol. p. 65,6; Roget, part 2, . 3, § 1. + Physiol. § 211, and Mat, Med. y. i. p. 1, ch. 1, p. 218 et seq. ; ¢ Physiol. t. ii. p.3,4; see also Fordyce on Di- » p- 84 et seq.; Baris on Diet, part =F: 17 et seq. ; Richerand, El, Physiol. § 3, p. Dumas, Ph siol. t. i. p. 187 ; Davy’s Lect. on Agric Chem. p. 73 et seq.; Londe, Dict. de Méd. et de Chir. art. “ Aliment,’’ t. ii. p. 1 et seq; Ros- tan, Diet. de Méd, art. «* Aliment,” t. i. p, 523 etseq.; Rullier, Ibid. Art. ‘* Nutrition,” t. xv. p. 161 et seq. 5 Kellie, in Brewster’s Encyc, Art. t «* Aliment. tof his Gul ian Lecture, p. 5, 9. § Ab on Diet; 13 in diet milk may be regarded as holding the first place, both from its nutritive and its digestible properties, and as such it has no doubt been provided by nature for the newly-born animal, when it requires a diet, which may be adapted to the delicacy of its organs in its novel state of existence, while, at the same time, it pro- vides for its rapid growth. We accordingly find that the three principles mentioned above are combined in milk ina manner the most proper for this double purpose, and that there is no compound, either natural or artificial, which is equally well suited to it.* Next to milk, with respect to its nutritive properties, we may class eggs of various kinds, the mus- cular fibre of animals, and their gelatinous and albuminous parts, very few of which, how- ever, are employed in diet until they have undergone the various operations of cookery. Of these operations the most important in their dietetical effect is the formation of decoctions or infusions, constituting soups of all descri tions, in which we retain the more soluble, and, for the most part, the more nutritive matter, while the residue is rejected. The fish which are usually employed in diet consist of a mach greater proportion of jelly and albumen than the flesh of the mammalia and of birds; these — are united, in most cases, with a con- siderable quantity of oil. The most nutritive of the vegetable proximate principles is gluten; it forms a considerable proportion of certain kinds of seeds, and more especially of wheat, and we accordingly find that in all those countries which admit of the growth of this plant, and which have arrived at any considerable degree of civilization, wheaten bread forms the most important article of vegetable diet, and one which appears the best adapted for all ages and all constitutions, Next to gluten we may rank farina, both from its valuable properties and from the extent to which itis employed. It enters largely into the composition of wheat and of the other seeds of the cerealia, also of rice and maize, while it constitutes a great proportion of the whole substance of the leguminous seeds and of tubers. It also forms the principal in- gredient of the chesnut, and of the esculent alge, so that, upon the whole, we may con- sider it as entering more largely into the aliment of mankind, in all different climates and situa- tions, than any other vegetable compound. Perhaps there is no proximate principle which contains in the same bulk a larger pro- portion of nutritive matter than oil, and we accordingly find that oil, as derived either from the animal or vegetable kingdom, enters largely into the diet of all nations. But it affords an example of one of those articles, which, al- though highly nutritious, is not very digestible without a due admixture of other substances, which may in some way render it more proper for the action of the gastric juice + It teay * Prout, ut supra, p. 12. + Itis upon this principle, rather than to the ab- sence of azote, that we should be disposed to account for the results of Magendic’ » in which 14 indeed be received as a very general rule that a certain quantity of matter, which in_ itself contains but a small proportion of the princi- ples which immediately serve for nutrition, is necessary for the due performance of the func- tions of the stomach, probably in some degree for the purpose of mere dilution or mechanical division. same remark applies to sugar as to oil. Sugar would appear to be one of the most nutritive of the proximate principles, but when taken alone or in too great quantity it deranges the digestive organs, and becomes ineapable of supporting life.* e difference in the different kinds of ali- ment between their capacity of affording the materials from which chyme may be produced, and the facility with which they are acted upon by the stomach, or in ordinary language, be- tween their nutritive and their digestible quality, has been distinctly recognized by various phy- siologists,t although it has not always been sufficiently attended to. We have some strik- ing illustrations of the fact in a series of expe- riments which were performed by Goss,t and in those of Stark,§ where the digestibility and the nutrition of various species of aliment bore no relation to each other, while they afford the most decisive proof of the advantage, or rather the necessity, of a mixture of substances, in order to produce the compound which is the best adapted for the action of the stomach. We have referred above to the difference in the digestive iets of the stomachs of diffe- rent classes of animals as depending on their peculiar organization. In many instances the difference is so strongly marked as to leave no doubt either as to its existence or as to the cause by which it is directly produced. But there are many cases where we observe the effect without being able to assign any imme- diate cause for it; where substances, which are highly nutritive and perfectly salutary to certain individuals, are apparently incapable of being digested by others. After making all due al- lowance for the effects of habit, association, or even caprice, there still appears sufficient ground for concluding that there are original differences in the powers of the stomach, which cannot be assigned to any more general prin- ciple. This observation applies principally to the individuals of the, human species, where such variations, or, as they have been termed, idiosyncrasies, of all descriptions are much more apparent than in any other kind of ani- mals. All other animals, even those which the most nearly resemble the human species, are much more uniform in this respect, being guided in the choice of their food principally by that instinctive feeling which leads them he found that animals could not be fed upon pure sugar, oil, or gum; Physiol. t. ii, p- 390, and Ann, Chim. et Phys. t. a = et seq.; see Bos- tock’s Physiol. v. ii. p. 467, 8. * Haller, El. Phys. xix. 3. 12; Stark’s Works, p. 94 et alibi; Pearson’s Synopsis, p- 104, 5, t Adelon et Chaussier, Dict. Sc, Méd. Art, “* Digestion,” t. ix. ¢ Spallanzani, Sar la Digestion, par Senebier, PD. Cxxxi...exl § Works, P. 89 et seq. DIGESTION. to select the substances which are the best adapted for their organs. But even here we meet with certain peculiarities, where animals prefer certain kinds of aliment, and where there is no obvious anatomical or physiological cause which can explain the effect. is, however, we may regard as an exception to the general rule, for there is perhaps no one of the functions in which we are enabled more clearly to trace the adaptation of the organ to the struc- ture and habits of the animal, than in what respects the supply of nutrition, including the mode of procuring the food, and the whole of the series of changes which it experiences from the digestive organs.* Liquids of various kinds constitute an im- portant part of the diet of almost all indivi- duals. They may be arranged under the two divisions of those liquids which we employ merely for the purpose of quenching thirst, or diluting our solid food, or such as are made the vehicles of nutriment, including various kinds of decoctions and infusions. The latter are derived both from the animal and the vege- table kingdoms, and when duly prepared form a species of food, which, as containing the most soluble and the most sapid portions, is, in most cases, both highly nutritive and diges- tible. But we observe here the same kind of idiosyncrasy to which we referred above, and which it frequently becomes necessary to attend to in the directions that are given respecting diet, and more especially to invalids and to children. The liquids that are employed for the pur- pose of quenching thirst, which are more pro- perly styled drinks, may be arranged under the two heads of vegetable infusions or decoctions and fermented liquors. Of the former a great variety have been employed in different coun- tries and at different periods, but in Europe, almost the only kinds which are in common use are tea and coffee. These cannot be con- sidered as in themselves affording any nourish- ment, but they are generally employed with the addition of some nutritive substance, and if not taken in excess, would appear to promote digestion, and to exercise a favourable influence on the system at large. Tt has been observed that all tribes of people that have made the least advances in Ags of life, either by accidental observation or tradition, have become acquainted with the process of fermentation, and have indulged in the use of certain species of vinous liquors. The making of wine is among the first transac- tions that are recorded of Noah after he left the ark, and the experiment which he made of its effects has been but too frequently repeated by his progeny. The basis of all vinous liquors being the saccharine principle, the grape has been naturally had recourse to in all those of the world which are adapted to the growth of the vine; in the more northern regions, as in our own island, different species of grains are employed, in which the sugar is evolved by an artificial process, while in the torrid zone, * Bostock’s Physiol. v. ii. p. 469, 70. -— oe DIGESTION. 15 other saccharine juices, procured from certain tropical plants, are employed for the same pur- pose. the fermented liquors of our own coun- try generally contain a considerable quantity of mucilaginous and saccharine matter, which still remains undecomposed, and which is directly nutritive; but fully fermented wines are only indirectly so, as aiding the digestive ers by their stimulating effect on the stomach. It is generally admitted, that the operation of alcohol, when properly diluted, and when taken in moderate quantity, is favourable to the health of most individuals who are engaged in laborious pursuits, and have occasion to exert the full powers of the system. But the almost inresiatitte temptation to excess, and the fatal consequences which thence ensue, both to our ot hageg and our mental constitution, have long the subject of deep t and severe re- prehension, both to the physician and the mo- ralist, and it may be asserted, that of all the ifts which providence has bestowed on the uman race, there is none which, according to the present state of society, would appear of such dubious advantage as the knowledge of the process by which one of the most nutritive articles of diet is converted into one of the deadliest poisons. We have now abesey a eg > epee v merally employed in diet, which are not ilieaintres cateiivs, but are added to our food, for the purpose of rendering it more agree- able to the palate. These are the various arti- cles styled condiments; they may be classed under the two heads of salts and spices. There is so very general a disposition among all classes of people in all countries to relish sapid food, that we are led to conceive that there must be some final cause for it, independent of the mere gratification of the senses, or that this gratifica- tion is made subservient to some more import- ant purpose. With respect to what is termed common salt, the muriate of soda, we observe, in many cases, the same relish for it among the lower animals as in man. We have well au- thenticated accounts given us, by various tra- vellers and naturalists, of the extraordinary efforts which are made by the beasts of prey which inhabit the great African and American continents, to obtain it.* We can scarcely therefore doubt that it must be, in some way or other, essential to the well-being of the animal ; but whether it directly promotes the process of chymification, or whether it be taken into the stomach, for the purpose of being transmitted to the blood, and thus furnishing to the system the portion of saline matter which is always present in the animal fluids, must be considered as entirely conjectural.+ The other division of condiments, the spices, are yery numerous, and are derived from vari- ous sources, but are chiefly of vegetable origin. They are generally of a stimulating nature, and * Among these we may select the account given us by Mr. Hodgson, in his interesting letters from North America, vol. i. p. 240, 1, note. + Haller, El, Phys, xix. 3, 11; Fordyce on Digestion, p, 55. such as may be supposed to act, in the first in- stance, on the nervous system. Some of them increase the action of the heart and arteries, and some of them augment the secretions or excretions, but they differ essentially from alcohol, in not producing any thing resembling intoxication and the subsequent exhaustion, Thus they are much less injurious to the con- stitution, even when taken to excess, and are seldom liable to any stronger imputation than that of being useless. They afford some of the most remarkable examples of the effect of habit on the system, in changing or modifying our original perceptions, for it is very generally found that those substances to which we be- come, in process of time, the most attached, are such as, in the first instance, were not only perfectly indifferent, but even positively dis- gusting. Before we quit this part of the subject it remains for us to say a few words respecting the class of substances which are properly termed medicaments. The medicaments are nearly related to the condiments in their action on the system, but with this difference, that they are not only disagreeable to the ees but are, for the most part, incapable of being re- conciled to it by habit. But there is in fact no exact line of demarcation between them ; many of the articles which are usually consi- dered as condiments, being not unfrequently used in medicine, and some of what are gene- rally regarded as the most active and nauseous medicines, being employed by some individuals as agreeable condiments. th these classes of substances appear to differ in one essential particular from what are more properly re- garded as articles of diet, that while it is essen- tial to the operation of the latter, that they should be decomposed, and probably resolved into their constituent elements, the specific effect of the former seems to depend upon their acting on the stomach in their entire state. Nearly connected to this class of substances, and indeed differing from it only in degree, are the articles that are usually termed poisons. The term may, however, be regarded as entirely a popular designation, for as there is no active medicine which may not immediately destroy life by an excessive or improper administra- tion, so there are no substances, among those which are usually considered as poisonous, which May not, under certain circumstances, prove valuable medical agents. III. An account of the changes which the food experiences in the process of digestion.— We now proceed to the consideration of the third subject which we pro for our in- quiry, the nature of the change which the food undergoes during the process of digestion. In prosecuting this inquiry we shall consider in succession the various processes by which the aliment, after being received into the mouth, is brought into the state of chyle. These changes may be reduced essentially to three; the me- chanical division of the food, as effected by the operations of maceration, mastication, and tri- turation; the conversion of the alimentary mass into chyme, by the action of the gastric juice ; 16 DIGESTION. and lastly, the conversion of chyme into chyle in the duodenum.* After the account which we have given above of the organs of mastication, nothing further remains for us to say on the first part of the process; we ay RR conceive that the food, after it has been mechanically divided by means of the teeth or any analogous organ, is conveyed to the stomach, in order to be acted on by the gastric juice and converted into chyme.t The process of chymification consists in a certain chemical change, by which the aliment, from whatever source it may have been derived, and whatever may have been its origi- nal constitution, is converted into a uniform pultaceous mass, having certain specific pro- perties, which are different from those of the substances from which it is formed. And we may here observe, that this kind of change, which has been frequently spoken of as something of a mysterious or inexplicable nature, is perfectly analogous to what takes place in all chemical action, where the addition of a new agent imparts new properties to the mixture. The supposed difficulty in this case has arisen from an indistinct conception in the minds of many physiologists, both of the nature of chemical action generally, and of the appro- priate powers which belong to a living orga- nized system. The essential and exclusive functions of vitality may probably be all re- duced to two great principles of sensation and motion, as depending primarily upon the action of the nerves and the muscles. Chemical affi- nity is independent of these principles, but it is, in yarious ways, modified by their operation, by bringing the agents into contact, by separa- ting them from each other, and thus enabling them to produce new compounds, and when the compounds are formed, by removing them from the further action of the agents, and by conveying them to the situations when they are required, for the exercise of some new function. In the present case the glands of the stomach secrete a fluid possessed of specific properties ; by the act of deglutition, and by the muscular contraction of the stomach itself, the alimentary mass is conveyed to the part where it may be brought into contact and mixed with this fluid. Each portion of the aliment is successively subjected to the due action of this agent, and when the process is completed, it is carried through the pylorus out of the stomach, while a new portion of aliment takes its place and goes throngh the same process. ‘ In this part of our subject there are two * See on this subject Magendie, Physiol. t. ii, p. 81,2; Dr. Prout’s paper in Ann. Phil. vol. xiii and xiv. and Dr. Philip’s Inquiry, ch. vii. sect. 1. + It is necessary to remark in this place, that most of the older physiologists, and some even of a later period, have employed the terms chyme and chyle indiscriminately, or at least have not made any accurate distinction betweenthem. The words vdo¢ and xuj40¢ appear to be nearly synonymous in their original acceptation; see Castelli, Lexicon, and Stephens, Thes. in loco. The latest physiolo- gists have, however, for the most part, employed the two terms in the restricted sense which is adopted in this article. points which will require our particular atten- tion; first, we must ascertain the properties of chyme, and secondly, those of the gastric juice. It is commonly stated, that from whatever source the chyme is, derived, provided the stomach be in a healthy state, its properties are always the same,* and it must be admitted that, as a general principle, this would appear to be the case. In animals of the same species, notwithstanding the miscellaneous nature of the substances that are employed in diet, the result of the complete action of the stomach is a mass of uniform consistence, ia which So, peemuat sensible properties of the articles of food cannot be recognized. But this statement must be re- ceived with certain limitations, and is only ap- plicable to the ordinary diet, for we have reason to believe, not only that the chyme produced from animal matter differs from that of vegetable origin, but even that different species of vege- table aliment produce a different kind of chyme. The chyme from fruits or green vege- table matter is notoriously more capceat to ys into the acetous fermentation than chyme ormed from farina or gluten, a circumstance which must depend upon a difference in their chemical constitution. We also know that the same kind of aliment is differently acted on by the gastric juice of different individuals; but this may probably depend upon some variation in the nature of the gastric juice itself, and is therefore to be referred to a different principle. Disregarding, however, for the present what may appear only exceptions to the general rule, we must inquire into the nature of the sub- stance which is found, under ordinary cireum- stances, in the proper digestive stomach, after it has experienced the full operation of the gastric juice. Although many observations have been made upon the pultaceous mass which is thus produced, our information re- specting it is not very precise; we are told little more than that the texture, odour, and flavour of the food employed are no longer perceptible, and it is said to have slightly acid properties, or rather to be disposed to pass into the acetous fermentation. As we remarked above, the change which the food undergoes is to be regarded as the result of chemical action, where not merely the mechanical texture and the physical properties of the substance are changed, but where it has acquired new chemi- cal relations. This conclusion is deduced from a number of very interesting experiments, which were performed successively by Reaumur, Stevens, and Spallanzani, and which consisted in insert- ing different kinds of alimentary matter into perforated tubes or balls, or inclosing them in pieces of porous cloth. These were introduced into the stomach, and after some time were re- moved from it and examined, when it was found that the inclosed substances had under- gone more or less completely the process of chymification, while the enclosing ly was * Haller, El. Phys. xix. 4, 31; see the remarks of Tiedemann and Gmelin in the third section of their researches. DIGESTION. not acted upon, yor’ tbe decisively that the effect was not uced by a meré mecha- nical operation.* The results of these experi- ments have been confirmed by some remark- able facts, which bear still more directly upon the point under investigation, where certain in- dividuals have had preternatural openings made into the stomach, either from accident or dis- ease, while the functions of the appear to have been but little, if at all, impaired. B this means the operation that is going farwards in this organ may be minutely watched in all its various stages, and we are enabled to ob- serve the change which the food undergoes from the time that it enters the stomach until it passes from the pylorus, and to compare the changes which the different kinds of food ex- perience during the progress of the whole mass. A case of this kind is related by Circaud, where an individual lived many years with a fistulous opening into the stomach ;+ but a much more remarkable case of the same de- Scription has been lately communicated by Dr. Beaumont. The individual in question was wounded, early in life, by a shot in the epigas- tric region, which perforated the stomach. After some time the wounded part healed, with the exception of an aperture two and a half inches in diameter, which communicated with the stomach. He lived many years in this state, in — health and vigour, so as to be capable of following a laborious occupation, while the fistulous opening still remained. Under these circumstances he was made the subject of experiment by Dr. Beaumont, who for the space of eight years continued his ob- servations, with great assiduity and minuteness, on the action of the stomach both in its ordi- nary state, and when subjected to different con- ditions, for the immediate purpose of the expe- riment. We may remark generally, that the results of the experiments confirm those of Spallanzani in their most essential particulars, and at the same time enable us to decide upon some °° which were left imperfect by that naturalist. Among the more important points respectin the formation of chyme, dene a 93 Jr GQ» ceca, g' g’, ceca opens into the central part of the body at the root of the ceeca. Such is the structure in the Asterias, but in some other genera belonging to the tribe of Asteroidea it is different. In Ophiura, Eu- ryale, and Comatula, in which the rays are very long and slender, the cceca are mere cel- lular dilatations of the stomach, and do not extend into the rays. Comatula moreover dif- fers from all the tribe, inasmuch as its alimen- tary canal has two openings, a mouth and anus, situated near to each other on the ventral sur- face. The mouth of the star-fish is very dilatable, so as to admit large mollusca in their entire 38 shell. The gullet and part of the stomach are usually everted, protruded, and applied round the object to be swallowed, which is then drawn in. The hard or indigestible matters, such as the shells of mollusca, are discharged by the mouth. The star-fish is said to be very de- structive to oyster-beds, and is xe ag be- lieved to suck the animals out of their shells. Bishop Sprat, in his History of the Royal Society, informs us that great penalties are laid by the Admiralty Court upon those en- gaged in the oyster-fishery who ‘ do not tread under their feet or throw upon the shore a fish which they call a Fine tenth: resembling a spur-rowel, because that fish gets into the oysters when they gape, and sucks them out.” ‘Tredemann found the ceca to contain a grey- ish-white fluid which he supposed to be di- gested aliment ; others again, such as Meckel, regard the coeca as secreting organs, analogous to the biliary organs of many invertebrate ani- mals, with which, it must be allowed, they agree in several respects. : b. The mouth of the Echinus is an orifice situated in the middle of the circular mem- brane which fills up the lower aperture of the shell (fig.15, a.) The points of the five teeth are seen within it, and at no great distance from its circumference the ten tubular tentacula (d) are observable, which have been already described. The teeth are set in five moveable sockets or jaws which surround the commence- ment of the gullet, and with the addition of some accessory pieces form the singular struc- ture usually named Aristotle's lantern. The lantern (figs. 10, 17,and 18) has the appearance ofa five-sided pyramid placed with its apex Fig. 17. Dental apparatus of the Sea-urchin viewed Srom above. downwards or towards the mouth, the gullet (a) rising through its centre. It is made up of five smaller hollow pyramids (h,) which are the sockets of the teeth. Each lesser pyramid is three-sided ; its external side (fig. 18, h’,) which forms one of the faces of the greater peannes presents an opening in its upper alf which is closed by membrane ; its lateral faces (fig. 18, h, h,) are applied to the cor- responding sides of the adjacent sockets, with which they are connected by short muscular fibres (p); they approach each other at the inner "arches, and descending inwardly are inserted ECHINODERMATA. A, two sockets with teeth, B, single socket with of Echinus esculentus. its tooth viewed on the outside, edge of the socket, but do not meet. The tooth (¢) is prismatic, very long, and lodged in a groove formed in the external side of the socket ; its point projects beyond the apex of the socket; its opposite extremity or root rises above the base, oes it is bent inwards and downwards and inclosed in a membrane. The teeth are very hard at the point, but softer towards the root, where they are easily sepa- rable into transverse scales or plates with a fine silky or asbestine lustre; they seem to grow continually at the root, and wear at the point as in the Rodentia. Ten additional pieces contribute to form the lantern. Five these (i) are oblong and flattened, and are placed horizontally, in a ra- diating manner, on the upper surface of the lantern, occupying the intervals between the bases of the lesser pyramids. The other five (k) are placed directly over the first; they are longer but more slender, and bent in a semi- circular form, the convexity being upwards; their central ends are articulated with the cor- responding extremities of the horizontal pieces ; the outer ends are bifid and give attachment to ligaments. The muscles and ligaments belonging to the dental apparatus partly pass between its dif- ferent pieces, and partly connect it with the border of the shell. It will be recollected that the border of the shell forms five processes (figs.10 and 17, g,g, g,) which rise in the form of arches into its cavity round the lower aper- ture. Ten muscles (m, m,) arise from these into the lesser pyramids or sockets near the point. Two of these muscles come from eve arch, and diverging are inserted into different pyramids, so that each pyramid receives its two muscles in a converging manner from two adjacent arches. The muscles described draw outwards the sockets separating them and widening the mouth. Other ten muscles (n, n,) arise in pairs from the border of the shell in the intervals of the arches, and, ascending, are inserted into the outer surface of the sockets near their base, each socket receiving a pair. These are antagonists to the last described; they move the points of the pyramids, and consequently the teeth Seward and against each other. Five muscles composed of short ECHINODERMATA. transverse fibres (p, fig. 18,) unite the lateral surfaces of the sockets, and serve to approxi- mate them, acting collectively as a sort of sphincter, and as antagonists to those first de- scribed. Lastly, five muscles (figs. 10 and 17, 0, 0, 0,) pass between the semicircular pieces on the upper part of the lantern. Besides the muscles described, there are ten very thin whitish bands (s, s,) which arise in pairs from the external forked extremities of the semi- circular pieces, and are inserted into the border of the shell in the intervals between the arches. Tiedemann describes these bands as muscles ; Meckel, on the other hand, considers them as ligaments; in the E. esculentus they certainly seem to us to be ligamentous. two liga- mentous filaments pass from the central end of every semicircular piece to the gullet. A co- vering of the peritoneum envelopes the dental a or extending to it from the border of e shell. The ceso s . 19, a,) rises through the athens or Ph 5 is Posten by fine ligaments, and after a few curvatures termi- nates in a wider part of the alimentary canal, somewhat in the same way as the small intes- tine joins the great in the human body. The wider portion (b, 6,) of the canal turns twice round the inside of the shell in a waving Manner, and terminates at the anus (c). In Fig. 19. Internal view of Echinus sexatilis. A, under half; B, upper. its second or superior circuit it changes to an opposite direction, but its flexures in both cir- cuits are el. The tissue of the alimentary canal is very delicate, the external tunic is formed by the peritoneum, which attaches the intestine a mesentery to the shell, lines the inside of the latter, and is reflected over the ovaries and the lantern. The inner coat of the intestine is soft and of a brownish-yellow co- lour; between it and the external, Tiedemann States that delicate longitudinal and circular muscular fibres are distinguishable. The Echini are generally believed to feed on mollusea and crustacea, and in corroboration of this, Tiedemann states that he has found in the Echinus sexatilis small univalve and bivalve shells entire among the excrements, besides fragments of larger ones. Blainville,* on the other hand, could never find any thing else than sand in the alimentary canal, and he re- marks that the general opinion as to the carni- . * Dict, des Sc. Nat. art. Oursin, 39 vorous habits of the sea-urchin is probably more an inference from the structure of the teeth and jaws than the result of observation ; he, however, adds that M. Bose had witnessed an echinus in the act of seizing and devouring a small crustaceous animal. Jn the intestine of the E. esculentus we have usually found numerous small morsels of sea-weed, for the most part encrusted with a flustra. The excre- ments, which are in the form of small round pellets about the size of peppercorns, consist chiefly of sandy matter with fragments of shells, but it would be difficult to say whether these are the remains of digested mollusca or merely a portion of the usual testaceous debris so abundant in sand and mud. The principal difference of the alimentary organs in the different genera of Echinida de- pends on the position of the anus and the presence or absence of teeth. In Scutella, Clypeaster, Fibularia, Echinoneus, Galerites, Ananchites, and Spatangus, the anus as well as the mouth opens on the under surface. In Echinus, Cidaris, Cassidula, and Nucleolites, it is situated on the upper surface; in the first two exactly in the centre, in the last two ata greater or less distance from it. The teeth are wanting in Spatangus and Cassidula. c. The alimentary canal of the Holothuria is Fig. 20. Holothuria tubulosa : alimentary canal and blood- vessels. The respiratory organ, c, c, is cut short. 40 very simple (fig. 20, ¢, f, g, h.) At the mouth it is surrounded by the tentacula and calcareous ring already described, it passes back- wards on the right side the whole length of the body (from e to 7;) then bending forwards it returns to near the mouth (from f to g,) and at last runs back again to the posterior extremity (from g to h,) where it terminates in a short and wide cloacal cavity (d), common to it and the respiratory organ, and opening externally at the anus. The intestine is fixed by a mesentery, and the cloaca is con- nected to the parietes of the body by numerous muscular bands de- rived from the transverse muscles. The coats of the canal are thin; Tiedemann enumerates three, an external derived from the perito- neum, a middle which is very vas- cular and contains muscular fibres, and an internal or mucous. In H. tubulosa a small part of the canal near its commencement is wider than the rest, has thicker coats, and is more decidedly mus- eular; Tiedemann regards this as the stomach. In H. pentactes, the part immediately succeeding the esophagus and ex- tending nearly to the first flexure, is somewhat cellular and at the same time wider, but thin- ner in its coats than the rest of the canal; this part is considered to be the stomach by Meckel. It is a singular fact, which it appears was first noticed by Redi, that several species of Holothuria, on being taken from the sea and put into a vessel of sea-water, discharge their intestine and part of the respiratory organ through the anus. This operation is effected by repeated contractions of the cutaneous muscles, and some naturalists are disposed to regard it as a voluntary act. 4. Respiratory organs.—The Echinodermata breathe through the medium of sea-water. In the star-fish and urchin the water enters the body, passing into the space in which the viscera are lodged, and this cavity, which, as already stated, is lined by a peritoneal mem- brane and occupies the greater part of the body, is generally regarded as the chief seat of the respiratory process. In the Holothuria the water is alternately drawn in and expelled from eAebalee respiratory organ ramified within the ly. a. In the star-fish the water is generally be- lieved to enter and issue from the body b: numerous small tubes on the surface, whic have accordingly been named the respiratory tubes. These are very small, membranous, and in figure somewhat conical (fig. 298, ¢, c, aes vol. i.); they communicate at their e with the interior of the body, and are perforated at the summit by an orifice which can be very accurately closed. Most of them are placed in groups or patches, and opposite ECHINODERMATA. eet a Portion of the skin of Asterias rubens, seen on the inside and magnified. ¢, ¢, peritoneal membrane raised, each group the fibrous membrane forming the wall of the body presents on its inside a shal- low pit (fig.21, a; fig.298, vol.i. e; fig.16, s,s,) perforated with holes, through which the tubes communicate with the internal cavity. The tubes are formed externally of the superficial: layer of the skin, and are lined in the inside by a prolongation of the peritoneal membrane. This membrane lines the parietes of the body, and is reflected over the contained parts; at least it covers the stomach and ceca, and hie bably also the ovaries and vesicles of the feet; opposite the perforated pits it sends prolonga- tions (b, b,) through the holes into the tubes, ~ may be easily seen on stripping off a portion of it. There can be no doubt that sea-water enters the peritoneal cavity. The animal slowly dis- soci itself with that fluid, and again, but at no stated interval, gives out a portion of it: this is obvious from the fact that the same animal may be seen distended at one time and flaccid at another. Naturalists are generally of opinion that the water enters and issues by the respiratory tubes, and indeed no other orifices have been discovered; we must, however, freely own that we have never been able actually to observe its passage through these tubes. The peritoneal membrane seems to be the principal seat of respiration; spread over the viscera and the parietes of their containing cavity, and lining the respiratory tubes, it pre- sents a great extent of surface continually in contact with the surrounding medium; and we have found that a beautiful provision exists for maintaining currents of water along the mem- brane, and thus effecting that constant reno- vation of the fluid in contact with its surface ECHINODERMATA. 4i which is required in the respiratory process. These currents are produced by means of cilia ; they are more particularly described in the article Crita, to which we refer the reader. Ciliary currents take place also on the external surface of the body, which probably partakes in the process of respiration ; we have more- over observed them within the tubular feet and on the internal surface of the stomach and ececa; in this last situation they are probably subservient to digestion, but their use is more fully considered in the article referred to. b. The respiratory system of the sea-urchin is very similar. The water enters the bod through membranous respiratory tubes, whic are collected into ten small bunches (fig. 15, e, €), situated on the under surface of the animal at the border of the shell, and opening internally by ten perforated pits like those of the Asterias. The fluid being introduced into the peritoneal cavity,is moved along its parietes and over the surface of the alimentary canal, the ovaries and the vascular lamine of the feet, by the action of cilia. Ciliary currents have also been observed on the external surface of the body, c. The respiratory organ of Holothuria (fig. 34, f; f, h, p. 109, vol. i.) has some resem- blance in form to that of air-breathing animals. It is a very long membranous sac, placed within the body, which opens into the cloaca near the rectum and extends forwards from thence nearly the whole length of the body, either single, or (as in Holothuria tubulosa) divided into two main branches (fig. 20, ¢, c, cut short, Jig: 34, ff, p- 109, vol. i.), which in the vicinity of the cloaca are joined by a short common stem. One of these branches is intimately connected by bloodvessels to the intestine, the other by muscular fasciculi to the parietes of the body. The sac, whether single or bifid, gives off a great many lateral branches, which after successive divisions ter- minate in shut or blind extremities. Both stem and branches contain distinct circular and longitudinal muscular fibres, and contract on being irritated. In the act of respiration sea- water is drawn into and expelled from this organ, and its entrance and exit, which may be readily seen at the cloaca, occur in some species so often as once, twice, or even three times in a minute. The alternate inhalation and expulsion of the fluid are effected partly by the action of the muscular parietes of the body, but Feces, it would appear, by the muscular fibres of the organ itself for Tiede- mann observed the process. still to go on, though with diminished activity, when the animal was cut open and the organ exposed. Cuvier states that the sac in some species is without branches. 5. Vascular system.—A system of vessels for the circulation of the blood exists in the animals under consideration. The tenuity of their coats, however, and pale colour of their contents render it extremely difficult to trace completely the distribution of these vessels, and we pica find that the descriptions of them given by Tiedemann and Delle Chiaje, the principal authorities on the subject, differ materially from each other. According’ to Tiedemann the proper sanguiferous system is, in its distribution, in a great measure confined to the alimentary organs and ovaries, or to these and the respiratory organ where such is present; he therefore supposes that the canals which convey the fluid of the feet serve more- over as nutritious vessels to parts of the body also supplied by the sanguiferous system. In short he conceives that there are two systems of nutritious vessels distinct from each other, the sanguiferous system, confined to certain organs already named, and the vessels of the feet, destined to nourish another set of parts; the vessels of the first system carrying blood, those of the second a nutritious fluid secreted from the blood. Delle Chiaje on the other hand maintains that the two orders of vessels communicate together and form but one sys- tem. From our own observations on the Asterias we are disposed to conclude that the vessels of the feet form a system a from the bloodvessels, as is maintained by Tiede- mann; but there seems considerable reason to doubt whether, as that author supposes, they serve as the nutritious vessels of the Ee in which they run; for even according to his own admirable description it does not appear that they ramify in the tissues, if we except, perhaps, the skin of the Holothuria. Moreover their contained liquid does not present the usual characters of blood or of a fluid adapted to nourish the textures; it is true there are float- ing particles suspended in it, but the clear fluid when filtered yields no trace of animal matter, but agrees almost entirely in com- position with sea-water; at least such is the ‘result of our examination of it in the Asterias. The vessels of the feet having been already de- scribed, we have here only to give an account of the proper sanguiferous system, following Tiede- mann as our leading authority, but at the same time stating the more material points in which Delle Chiaje differs from him. a. In Asterias a delicate vessel runs along the upper surface of each of the ceca. There are, of course, ten such vessels in Asterias aurantiaca (from which the description is taken) corresponding in number with the cceca (fig. 22, v, v). They commence near the extremity of the rays, and, receiving branches from the branches and lobes of the ceca, proceed to the central part of the animal, where they terminate in a circular vessel (7) which runs round the upper part of the body on the internal surface. e circular vessel also re- ceives ten branches (y,y) from the ovaries, and five from the stomach, which before joining it unite into two (w). The vessels described seem to constitute the venous system, and Tiedemann further supposes that the cecal and gastric veins convey the chyle or nutritious rt of the food from the alimentary organs. e circular vein opens into a vertical canal (h, and fig. 12, h), which descends along the rominent angle ‘between two rays, inclosed in the same membranous sheath with the sand canal already described, and terminates in an 42 ECHINODERMATA. {? edd ait t) Asterias aurantiaca opened from above. A, ray with the ceeca 2 g,in their place. B, ceca removed ; vesicles of feet d, seen. C, vesicles of eet removed to s ew the calcareous segments of the ray. D, skin forming roof of the body and rays A, B, C, raised ; vessels seen on its inner surface with collapsed stomach, f, &c. inferior circular vessel. The descending canal is dilated in the middle; its gga | thick brown coloured parietes are smoot externally, but reticulated on the inside and composed of interlaced fibres, which Tiede- mann found to possess muscular irritability. He accordingly considers this canal as the heart. The inferior circular vessel (which must not be confounded with the circular canal connected with the feet) surrounds the mouth on the outside or inferior surface; it sends out five branches which pass into the interior of the body, and are distributed to the Stomach, ceca and ovaries. Tiedemann re- | soe these branches with the circular vessel tom which they proceed as arteries, and he thinks it probable that their minute ramifica- tions open into the radicles of the veins, though from their delicacy he has not been able to ascertain the fact by injection. Tiedemann’s view of the function of the respective vessels is derived solely from a con- sideration of their anatomical disposition, and while in the same way it may be inferred that the blood circulates in a direction conformable with this view, it must nevertheless be kept in mind that no direct physiological proof of such a course of the blood has been yet ob- tained. Besides the vessels described, Tiede- mann found yet another circular vessel sur- rounding the mouth on the under surface and placed more superficially than the last men- tioned ; it is of an orange colour and sends a branch along each of the rays, in the groove which is on the middle of their inferior sur- face, He could trace no connection between ECHINODERMATA. this vessel or its branches and the rest of the vascular system, and he professes himself at a loss to conjecture what may be its function. According to Delle Chiaje the circular ves- sel (i, i, figs. 12 and 22,) into which the canals of the feet open receives also the veins from the up- per surface of the ceca and stomach. The same vessel, which he names the venous sinus, gives out—1. twenty short dentalarteries; 2.the mesa- raics to the under surface of the ceca; 3. five vertebral arteries which open into the vesicles of the feet; 4. the radial to the under part of each ray; 5. the dorsal arteries to the upper part of the ray, which extend their ramifications to the external surface of the body. b. Echinus. A circular vessel, supposed to be of a venous nature, surrounds the anal extremity of the intestine (fig. 19, at c), being situated on the internal surface of the shell. A vertical vessel (e, cut short) descends from it towards the lantern and opens into a short oval canal (4) with muscular parietes, which exhibits during life slow but distinct contrac- tions and dilatations, and which is therefore considered as a heart. The heart is situated near the commencement of the intestine ; a vessel (i, %, 1,7) issues from it which first sends branches to the csophagus and the muscles and membranes of the lantern, and then rans along the whole intestine on its inner border, first increasing somewhat in diameter, afterwards gradually diminishing as it ap- proaches the anus, where it terminates. This vessel gives off at all points of its course small branches to the intestine; it contains a dark yellow fluid coagulable by alcohol, and its Cates contract on mechanical irritation; iedemann conceives it to be an artery. Ano- ther seme fy k,k,k) equal in length to the last described, but not directly connected with the heart, runs along the intestine on its outer or mesenteric border; it also is widest in the middle of its course, from whence it may be traced in one direction as far as the lantern, and in the other to the vicinity of the anus. Along its whole course this vessel receives small branches from the intestine, and gives off branches from its other side, which pass along the mesentery to the internal surface of the shell, and are ramified on the lining or peritoneal membrane. Tiedemann regards this vessel as a vein; but as it does not directly communicate with either the heart or the cir- cular vessel, he conceives that the fluid which it circulates is conveyed into it by one set of branches, and out of it by the other, the in- testinal being its entering and the mesenteric or peritoneal its issuing branches. Lastly, the circular vessel placed round the termination of the intestine receives several vessels which come from the peritoneal lining of the shell, and whose commencing branches are probably continuous with the terminations of the peri- toneal branches from the longitudinal vein. Tiedemann conceives the circulation to take place in the following manner. The blood passes from the circular vessel into the heart ; it is then Fig ta along the artery and its branches ; from these it passes into the veins 43 \ of the intestine, which also absorb the chyle, and the mixed fluid is conveyed into the great longitudinal vein; it next passes into the branches of this vessel, which are distributed to the lining membrane of the shell, and is at last conveyed back by another set of vessels into the circular vein, from which we have sup it to set out. That this is the course of the circulation is inferred from the anatom of the circulating organs. On similar grounds Tiedemann with great probability supposes that the blood undergoes its respiratory change, at least chiefly, in its through the vessels of the peritoneal membrane, being there most effectually exposed to the influence of the water; he accordingly compares the branches of the great vein which ramify on that membrane to pulmonary or branchial arteries, and the vessels which return the blood to the circular vein, together with that vein itself, to pulmonary veins. He found that the fluid contained in the longitudinal vein was of a yellowish white colour, from which cir- cumstance, as well as from the fact that he could discover no special chyliferous vessels, he inferred that the chyle was absorbed by its intestinal branches. is vein did not con- tract on the application of stimuli. Delle Chiaje’s description of the vessels of the Echinus is in substance as follows. An annular vessel surrounds the wsophagus; it receives the termination of the intestinal vein, and gives out the intestinal artery, which like the vein runs along the intestine, and also five esophageal arteries, which before ramifying on the mouth communicate (by means of a brarich passing between the muscles of the teeth) with the dorsal arteries. These last are the canals of the feet; they run along the ambulacra to the anus, where, according to Delle Chiaje, they form a ring, and in their course send lateral branches into the feet. ¢. Holothuria. A vessel (fig. 20, i, i, i, i,), which Tiedemann conceives to be the great artery, runs along the free border of the intes- tine. It is widest in the middle, and gradually disappears posteriorly in the neighbourhood of the cloaca, while anteriorly it forms an annular vessel (at e) round the stomach, out of which branches proceed to the stomach, the ovaries and the sac connected with the canals of the feet and tentacula formerly described. A short but wide anastomosing anal (cut at k, k,) nes from the artery about the middle of the t portion of the intestine, to join it again at the middle of the second portion (2m), that is, nearly about the middle of the arterial trunk itself. Slow contractions, followed by dilata- tions, were observed by Tiedemann in this vessel; they commenced at the middle or widest part, and proceeded in opposite direc- tions to its two extremities, carrying on the light brown-coloured blood contained within it in a corresponding manner. The main artery, which seems thus also to serve the purpose of a heart, sends in its course numerous branches to the intestine, from these the blood is received by the commencing veins, which, uniting to- gether at the opposite or attached border of the 44 intestine, form a plexus along its first portion, whose branches ultimately terminate in a large longitudinal venous trunk (n,n,n,n). The blood is conveyed from this great vein to the right branch of the respiratory organ, (which lies between the first and second portions of intestine,) by a considerable number of vessels which divide like arteries into smaller ramifi- cations on the lung, and may therefore be com- st to pulmonary arteries. The capillary ranches of these vessels transmit the blood into the commencing pulmonary veins, which, uniting into larger and Jarger branches, ter- minate in a third longitudinal vessel (0), 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 ~~ \v Ss 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 a 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- ECHINODERMATA. buted to the stomach. Tiedemann could dis- cover no ganglia, but others describe minute ganglia as existing at the points where the diverzing filaments originate.* The Echinodermata have not generally been supposed to possess any other sense than that of touch. rofessor Ehrenberg has how- ever recently called attention to certain parts in the Asterias, which he is disposed to re- gard as organs of vision.t 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 ee 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- Sey the existence of such a system in the olothuria, 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 eso- 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 cesophageal 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 csophagus, 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 arecent notice of some obser-_ vations on the Echinus by M. Van Beneden, it — is stated that he distinctly recognized a nervous collar surrounding the cesophagus. 6. Generative organs. —The only organs hitherto discovered in the Echinodermata, which * Grant’s Comparative Anatomy, p. 184, + Miiller’s Archiv fiir Anatomie, Physiologie, &c, 1834. p. 577. ¢ Comparative Anatomy, p. 184. y ’ ee he ee ECHINODERMATA., 45 can with certainty be regarded as belonging to the generdtive 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; QO. 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 arcte connexis, altera supina.”* a. The ovaries of Asterias seem to vary in number according tothe 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 ies of an oblong cluster of ramified tubes, Ofigs.12and 16, 0,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 (fig. 22, 0, 0). 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 Ophiura has also ten ovaries, which do not lie in the rays, but in the central part of the animal, and which, according to Meckel, ape externally by orifices on the ventral sur- b. The Echinus has five ovaries, (fig. 10, c,) attached to the inside of the shell in the upper of the body, and occupying the spaces tween 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 es 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 r 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. e. The ovary of Holothuria tubulosa (fig. 34, m, ig 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 Groenlandica, 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, eightor 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 toa line in length, which he sup- poses were eggs or perhaps embryos. From a statement of O. Fabricius it would appear that the Hol. pentactes is ovo-viviparous : he says, “ est vivipara : mense enim Martio in illa 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 re 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 cicatri 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.”*+ BipLioGRAPHY.—Kleinius, Naturalis dispositio * Fauna Groenlandica, p. 353. + Reaumur, Mémoires pour servir a l’histoire des insectes, tome vi. preface, page Ix. sq. 46 Echinodermatum, 4to. Lips. 1778. Linkius, De stellis marinis, fol. Lips. 1733. Blainville, Dict. des Sc. Nat. art. Oursin. Tiedemann, 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. Sharpey.) 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 ( Bradypus ), (fig. 24), constituting the Tar- digrada of Illiger; to the second, the Ant- eaters (Myrmecophaga ), (fig. 25), the Arma- Fig. Skeleton of the Ant-eater. EDENTATA. dillos ( Dasypus ), (fig. 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 (fig. 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 organization 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 24. -~ \r EDENTATA. Fig. Fig. 47 26. the Manis. 28. Skeleton of the Megatherium. stretching ed one hands, on in the Ai or oe celled mer Br t length, to enable them to lay hold of erin eas, 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 eon Hite 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 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 Linnean ‘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 Ch/amyphorus 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 (fig. 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 ofa square figure. In the Armadillos (fig. 30) and in the Fig. 30. Head of the Armadillo. EDENTATA. 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 (fig. 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 Manis (fig. 32) it is absolutely wanting. In the Arma- Head of the Manis. dillos it is somewhat more fully developed ; it is larger and higher and reaches the tem- ral bone by its posterior portion. In the Sloths, especially in the Bradypus didactylus, 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 (fig. 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. Inthe 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 intermazillary 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 4 of development, especially in the genus Da- EDENTATA. 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 it 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. he 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 vertebre of the Ai, Bradypus tridactylus, 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 49 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 vertebra, and giving _ exist equally in the hog and the giraffe is in- _ deed a remarkable fact, and may be considered _ asastriking illustration of the law by which variations in volume in any particular system _ of organs are provided for rather by the differ- ence in yolume or in the relative proportions of the organs themselves, than by any abrupt _ change in their number. The supposed excep- ai tion to this law which now comes under our uf 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. skeletons in my own possession, however, have enabled me to demonstrate that the posterior 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 ara long in the Ant-eaters as wellas the loth. These vertebre are also generally more numerous in this than in most other groups—the great Ant-eater having sixteen, the Ai fourteen, and the Unau no less than twenty-three—a larger number than is found in any other mammi- ferous animal. The ribs offer some striking two of these vertebra (fig. 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- _ tebre, modified into a cervical form and func- tion, suited to the peculiar wants of the anirnal. The object of the increased number of ver- 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 jubata and M. didactyla 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 tebre in the neck is evidently to allow of a_ breadth of the ribs, but to a much less extent _ more extensive rotation of the head; for as than that just described, and the latter animal, VOL. II. E 50 at least in the remains lately described by Mr. Clifi, 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 vertebre 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- bre, consisting of a small longitudinal crest. The caudal vertebre 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 vertebra at least. The caudal vertebrae 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 Myrmecophaya didactyla the two branches are not united in the anterior two of them. The sternum offers a considerable developement of the manubrium or 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 considérable 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. 1in , 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 Awmerus is very much ideangased bee cylindrical, with the elevations but slightly marked. The ulna and radius are also 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 EDENTATA. complicated ole 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 (fig. 35) is no less suited to the same pur- Fig. 35. Hand of the Sloth. es. The carpus is as long as it is broad ; it is Sogitialh of prey 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 os 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 Ai, 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. Ina 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. The : femur 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 fibula are long and slender, and some- what curved ; the superior articular surfaces of the ¢ibia are Aat, that of the inferior extremity EDENTATA. small, triangular and slightly concave; but the most extraordinary articulation is that of the Jibula with the astragalus ; its inferior extremity terminates in a conical point, which enters and ding cavity in the latter lays in a corres one. 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 admirabl adapted to its habits than those Be ons whic! feet, it is _ have been previously noticed. 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 anteriorand 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, é Of the Edentata the consolidation of the tarsus, and the curious ogee oe the articulation of the oe with astragalus, e 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- tities, combine, with that security and facility of progression, the most effective means of ob- taining the animal’s peculiar food. roper.—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 , ined is facility in digging the ground, or weeding up . immense nests, in search of the insects which constitute the principal food these animals. The gigantic and is supposed to have fired upon roots, which it ‘S 51 snatched or dug up with its enormous claws. The scapula of the’Ant-eaters and Armadillos is found nearly like that of the Sloth; in the Myrmecophaga jubata 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 these processes. 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 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 hus 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. The radius is broad, robust, and strongly marked, particularly towards the carpal extremity. The hand in the Myrmeco- phaga (fig 36) and its kindred genus Manis Ss a of the Ant-eater. 52 offers a very remarkable structure. The ungueal phalunges, \ike 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 Orycteropus is also of a very remarkable conformation, particularly in the gigantic spe- cies of Armadillo, Priodonta gigantea (fig 37) Fig. 37. Hand of the Gigantic Armadillo. of Fr. Cuvier. Amongst the peculiarities of structure in this animal are the following. In add.tion to several remarkable anomalies in the carpal bones, the bone which results from the ossification of the fleror profundus muscle is very large, developed posteriorly into a large and irregularly formed head, articulated by large surfaces to the os semi- lunare 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 oy less striking peculiarities of structure. PP ns emur in general is of mo- > EDENTATA. 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 darsus 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 foot, upon the scaphoid ; it extends back- wards as far as the tuberosity of the os calcis, and thus forms a broad base to the posterior part of the sole of the foot. The Myrmecophaga jubata has also a supernumerary bone, but of 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 surface 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 avery 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 appear 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. 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 53 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 ints equally obvious, the Chlamyphorus ex- Fibits characters to be found in some species of Ruminantia and Pachydermata. On Skeleton of the Chlamyphorus 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 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, Tulpa Europea, than its external form and subterranean habits would induce us to 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 pel different; nor do the articulations of 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. “Ttresembles the Bradypus tridactylus in the form of Ly a and in 3 acute descending process of the zygoma, but here all comparison with the Sloth cae ie The skeleton of the Chlamyphorus will be * found to resemble that of the Armadillo (Dasypi _ Species plures) more than any other known — quadru n the peculiar ossification of the cervical vertebra ; in possessing the sesamoid bones of the feet; in the general form of all the bones, antont those of the pelvis, as well as in the nature of the external covering, they are oy similar; they differ however in the form and appendages of the head, in the com- position and arrangement of the coat of mail, _ and pay in the posterior truncated ex- % s There is a resemblance to be perceived in the form of some of the bones of the Chlamy- phorus to those of the Orycteropus capensis and _ Murmecophaga jubata, as might be expected in en as e 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 Tardigrada 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 Mammijera. 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 Tutusia 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. e stomach in the Sloths is very remarkably formed. In the Bradypus didactylus (fig. 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 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 Ai 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 >in. a Mase for the digestion of vege- table substances only. In the Edentata proper the stomach is, as may be expected, far more simple. In the Myrmecophaga didactyla it is of a globular form, and simple. Inthe Manis pentadactyla 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 cecal 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 ceca 1s so contracted as wholly to prevent EDENTATA. the passage of any feces into them. In the Manis longicauda there is not the vestige of a cecum. 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 liarities of consequence in a physiologi int 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 off 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 the genera Dasypus and Tatusia, comprehend- ing the Armadillos, and in Chlamyphorus, ex- hibits various modifications of a very extraordi- nary nature. The body of the Manis is co- vered with large imbricated scales, of a more or less rhomboidal form, of a horny consistence, and a reddish brown colour. e 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 of the head and tail, the axille, the middle of the belly, the inner surface of the thighs, and the soles of the feet, all of which ya excepting the latter, are furnished with a 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 of the limbs, and the whole of the tail. inferior parts of the body are not thus ; but scantly covered with hair, intermixed with a kind of hard warts or scales. Their armour is com of a helmet covering the upper part of the head, of a buckler over the adios, 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 t 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 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 — at every portion of this coat of mail, 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 concaye margin meets the origin of the tail. The cuirass of the Chlamy- phorus 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 ae pape of es ceickapes. It is composed of a series of plates of a square, mboidal, or cubical loa each et 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- 55 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 frontis, by means of two jarge paws, 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 down Sy 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 aor 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 vertebra, 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 vertebre extend up to the top of the back, beneath the pea mg 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 BIBLLOGRAPHY, see that of MAMMALIA. (T. Bell.) ELASTICITY (Germ. Springkraft, Fe- derkraft ) is that property of natural bodies in virtue of which they admit of change either of size or form from the npritayes of external force, resuming, upon the suspension of that force, their proper shape or volume. Though elasticity is a purely physical pro- rty, 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 sev 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 ag Bh ated of the material elements of iving ies 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 56 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, $c.—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 ere 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 part its original quantity, it has still elasticity enough to raise the valve. Another important law of elasticity in gases is that its power is jacreased 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 ELASTICITY. 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 we 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 tk sa 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 cau 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. e 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 medical his- al gg FA Es ES A: a a ES Se & =; ELASTICITY. these two properties were looked upon as identical; that as 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 ms 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 their 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 a) pee 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 wiih 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 1. 'y, elasticity is not destroyed by eath 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- uently be referred to the same source. But 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 op’ site direction, and by pushing analysis too i have attributed to imaginary forces effects which are the result of elasticity alone. We feel much diffidence controverting any doc- trine supported by the genius and authorit 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- 57 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 mes 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 aes 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- pa Spots to say, for example, that even in a dead artery there are two principles of con- traction which, though their mode of action is 4 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. e “vis mortua” 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—* Hee vis in partibus animalium perpetuo agere videtur, etiamsi non perpetuus effectus adparet. Vi- detur enim contractio re particule propriz a contraria contractione duorum elementorum vicinorum impugnari et distrahi, ut que breviores fieri non possunt, quin mediam par- ticulam distrahant. Id dum fit in omnibus, quies yidetur, que 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 eam yicinam, a qua trahitur, integramque incise membrane 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 forthem? 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 Conrrac- 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 lamin of the vertebrae to one another, and the ligamentum nuche 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 pea 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 itis expelled upon the —— 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 isremarkably 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. ee — ———————— * ELASTICITY. 59 4. Skin —The great elasticity of the cuta- heous tissue is exhibited in innumerable in- stances; the extension which it teeny in , in ascites, in cases of large fatt ond ser’ 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. tissue 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, edema, 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- pore as that which we are now considering ; r 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 removin accumulation of air or fluid contai 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 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 ina 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 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 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. ere 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 oung 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 ruge into which it is thrown seem destined to compensate for its im- perfect elasticity. g j 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 lace. By this simple contrivance the possibi- ity 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 ressure. 11. Fibrous membrane is remarkable for its very low degree -of elasticity; hence liga- ments and tendons often give way rather than yield toa 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- rtant sal in the mechanism of organized ings ; 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 tata for several distinct ends. It is sometimes employed asa 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 in protecting certain organs, such as the spimal 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 micas 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- at’ ‘ ; + _ various movements of active life. ~ downwards in inspiration. ELASTICITY. ready seen, possessed of extraordinary elasticity. Thechord, instead of filling the mt 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 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 s nothing in that icular, usually resents himself after his night’s repose. The elicate viscera of the thoracic cavity owe like- wise their safety in a great degree to the same me- chanisin. 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 im it property. We find, for ex- ample, 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 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 The elastic liga- mentum nuche, 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 61 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 erg rae 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 mo!lusea 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 ale 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 enablin them to make those enormous bounds by whi 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 Treland, to a height of twelve or fifteen feet, and falls beyond the obstacle which had op- sed 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 comesinto 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 Laennee 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 tfie 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 ease 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 Fiprous Tissve and MUSCLE, (John E. Brenan.) ELBOW, REGION OF THE; fold or bend of the arm. (Fr. plidu bras; 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 OE —<-— S$ ; : REGION OF THE ELBOW. 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 Taterally, 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 eure 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 inful sensation which is felt in the little ger and the inner side of the ring-finger ; in the depression external to the olecranon the ny ogi edge of the head of the radius can felt rotating immediately below the external condyle when pronation and supination of the are rmed. An accurate know- oa sied the relations of these parts is essential to the forming an accurate diagnosis in cases of fractures and dislocations in this 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- ion. 63 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, icularly 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 ha ses 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 Jean 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. ke 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-arm 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 : 64 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 syperficial 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 brachieus anticus; the ex- sion from the brachizus anticus comes orward 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 brachieus an- ticus to the aponeurosis of this region, it fol- lows as a necessary consequence that the con- REGION OF THE ELBOW. 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. : is 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 vene comites, one of which lies on either side of it; it lies on the surface of the brachizus 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 profunde and anastomotic branches of the brachial, as described in the article Bracurat Arrery. The vene comites of the brachial; radial, and ulnar arteries are double : these vessels are also accompanied b a deep set of lymphatics. The nerves whic traverse this region beneath the aponeurosis are, the median on the internal side of the brachial artery; the radial, which, descending between the brachizeus 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 alnar 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 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 cn 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 sibility of this occurrence should be constantly held’ in recollection in performing phlebotom 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 t 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. aceident is not so great when the vein is opened near its lower 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- ension of injury to the brachial wo ' external cutaneous nerve however, the trunk of which lies behind this vein, may suffer a puncture, in consequence of the lancet being too deeply, the consequences follow- affection extending along the branches of this nerve to their terminations. In those un- fortunate cases in which the brachial artery is red, should the wound in the artery not be closed and united by pooely regulated ure, the consequence likely to ensue may 4 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. LI. ARTICULATION OF THE ELBOW. ms which have been in many instances a pain-~ fu 65 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, ¢he varicose aneurism. (J. Hart.) ELBOW (ARTICULATION OF THE), ayxwy, 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. muscles which cover this articulation are, the brachiwus anticus, the infericr tendon of the triceps, and some of the muscles of the fore-arm anteriorly, the triceps and anconzus 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 of the greater tuberosity above would fall upon the external condyle; the internal ple a 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 a 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 ¥ 66 ARTICULATION an inch below the internal condyle, having be- tween it and this latter process a sinuosity in which the ulnar nerve lies ; itis 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 fosse 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 haye seen several others which occurred in Europeans: a second small fossa frequently exists a 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 coneave 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 arough 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 P * Handbuch der menschlichen Anatomie, band i. OF THE ELBOW. ligament consists of ae and perpendicular fibres arising superiorly from the front of the condyles and the part of the humerus imme- diately above the two anterior articular fosse, 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 fosse 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 fossa at the posterior margin of the olecra- non: between the radius and ulna and in the i wes: J ime 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 ee groove described above, dividing the Sigmoid cavity transversely. The synovial capsule adheres closely to the fibrous ligaments, except where masses of adi- hem are interposed, to which it is but ly connected. Motions.—The elbow is a joint remarkable for possessing great solidity, which is partly Owing to the extent of its osseous surfaces and cee in which they are ne into each other, to the strong lateral ligaments and the Sehttest wkd jen te it. ye The motions enjoyed by the elbow-joint are flexion and extension. Flexion may vary in degree so as to be com- = or incomplete: in complete flexion the e-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 fosse of the humerus, displacing the adipose masses from these cavities, the olecranon is brought downwards on the trochlea so as to be below the level of the condyles of the 8; the posterior part of the synovial capsule, the posterior ligament, and the triceps med aa inne are made tense, and to tl i mass in the rior articular fossa and othe posterior Dacor the trochlea: the anterior part of the capsule and the anterior ligament are relaxed, as are also the lateral ligaments. A dislocation is rendered ible in this state of the articulation, being effectually opposed by the hold which 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 cireum- ‘Stanced; the coronoid process being carried down is no longer applied to the front of the s, 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- od the degree of flexion ; hence a dislocation ofthe ulna forwards on the humerus is an acci- dent which never happens. __ In extension, the olecranon, ascending above the level of - candice is received into the ‘posterior articular fossa, displacing the adi substance which previously bavepied that iam, ABNORMAL CONDITION OF THE ELBOW-JOINT. 67 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 brachiwus 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 fulerum 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 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 —— 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 F2 68 ABNORMAL CONDITION 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 fower short fragment, which is pulled in this direction by the supinators and pronators taking their fixed point below. The prominence for- wards, forined 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 OF THE ELBOW-JOINT. 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 1s 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 fig. 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, * Sce plate xxvi. fig. 1, of Sir A. Cooper’s work on Fractures and Dislocations, ABNORMAL CONDITION OF THE ELBOW-JOINT. Fig. 40. Fracture and retraction of the outer condyle of the humerus. ay 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. He 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 was detached from the ulna, and that thus during extension the ulna slipped 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 the 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. Luration 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 astate of —- tion (fig. 41); the whole extremity is manifestly shortened ; the olecranon process rises very much above the level of the tuberosities; or, to k more correctly, with reference to the sition of the limb, which is always presented to 70 ABNORMAL CONDITION OF THE ELBOW-JOINT. Fig. 41. Luczation of both bones backwards. us for examination more or less flexed, this proce is placed much behind and somewhat elow 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 be integuments by the fingers, and we rceive in front an interval between it and the k 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 oon 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 disa) pear, to return again very shortly, when t 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 proves forwards; if the accident has been a uxation, 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 appeensy 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- ee ABNORMAL CONDITION OF THE ELBOW-JOINT. 71 Fig. 42. diable; the patient for ever loses the power of flexing the fore-arm, and the muscles of the arm become more or less atrophied; the powers of tion and supination also become impaired, but extension of the elbow-joint can ir A. Cooper had an Sepeete 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 natural Situation, an inch and ahalf. The radius was behind the external condyle of the os umeri, and the humerus was thrown forwards on the anterior part of the fore-arm, where it formed a large projection. The capsular liga- ment = torn deen h anteriorly to a year ex- tent; the igament remained entire. The biceps veo was slightly put on the stretch by the radius receding, but the brachia- lis anticus was excessively stretched by the ig position of the coronoid process of the 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 ossifie depositions. An in- teresting case of this kind is recorded by Cru- veilhier, and figured by him in his Anat. Pathol. te iv. fig. 1. Béclard also met with a simi- 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 rior ba of the fore-arm, which tendons almost identify themselves with the lateral 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 oj ni- ties ourselves of witnessing these com tions as the immediate result of accidents, Indeed we can scarcely conceive any complete luxation outwards to correspond exactly to the Sag age given; as we imagine that when- ever the bones of the fore-arm are completely thrown outwards, these bones must be drawn te luxa- Luxation outwards of both bones of the fore-arm, consecutive to caries Rd the trochlea and great sigmoid cavity of the ulna. immediately —— 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 elhow-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 itions to each other. In these luxations the bones of the fore-arm may be thrown ially outwards or partially inwards. In the luxation outwards, the cavity of the superior extremi 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 ide of Gineums fotmad by'the hand of the tailed, and an an; depression immediately above this. On the inner side of the arm we see the of the . 72 ABNORMAL CONDITION Pacsenee formed by the inner condyle of the rumerus, 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 laced under the internal border of the articu- ar 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 in the former case. We must add to thesea 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; 6, complete luxation of the bones of the fore-arm at the elbow backwards and inwards. a. Luvation 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- OF THE ELBOW-JOINT. 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. Luxvation 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. Luvations 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. fig. 2, in Sir A. Cooper’s work. ABNORMAL CONDITION OF THE ELBOW-JOINT. a. Lucxation 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 Gabe Tigaments 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. Lucxation 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. 6, 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 73 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 rhaps excused for exceeding our ordina’ imits 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 ee having a heavy boat-pole in his hands. 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 a 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 J 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 74 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 capden, appear- ance, and the fore-arm is much wasted.” This case seems to us important as proving three circumstances : 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. c. Luxation of the upper 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 ABNORMAL CONDITION OF THE ELBOW-JOINT. 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 Me 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- ital, in which was found this luxation, which ad 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 external 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 upper 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. 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 er great 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 aecident, and it cannot be re- laced without the assistance of art. It is nown to anatomists that the radio-cubital joint is not advanced much in its development in infants ; that the lesser sigmoid cavity is as t small and shallow; and that the coronary igament of the radius is proportionally longer and more yielding than it is destined to be in after life. is 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 ond usually seize them by the fore-arms, ese being at the time ina 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 iven to the head of the radius, the latter will 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 Pr. Coag eos episod : es. enital or original luxation of the superior extremity of the radius sot Ba Dupuytren is the first pathologist who has bien of the congenital luxation of the radius; he met with a case of the kind in 75 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 would 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 ; ‘he 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 lane of the outer condyle of the humerus. e 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 T6 ABNORMAL CONDITION OF THE ELBOW-JOINT. Fig. 44. 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 4 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). Tn referring to it, the author states that the bones of the fore-arm wereanchylosed, that the form of the ca- pitulum was lost, that the head of the radius was luxated completely backwards, and that the ulna alone remained in articulation with the hu- merus; the parallelism between these two cases will be still more fully seen, when, speaking of the lower articular extre- mity of the humerus, we find that he says,“ Figura ergocapituli periit.Rotula unica, sed major forma- tur;” and of the ulna, “ insignem acquisivit am- plitudinem et totam infe- riorem ossis humeri PR ‘right, Meanbid = 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- ae of the radius and ulna, belonging, e is certain, to the same class of diseases now under consideration, namely, congenital luxations of the radius. In this preparation Congenital luxation of the radius backwards. Fig. 45. Congenital malformation there is a very oblique relative position of the bones of the are 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 (fig. 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 ordisease. Sup- pose, for argument sake, it be admitted that, from long disease, the form of the : capitulum was altogether bes hig Bork lout, when the peda eas no it was found as longer in contact with it, and long as the ulna, that the acquired breadth of Fig. 46. eee _* Pea Serre ee 0 Nes eo jee tee = ABNORMAL CONDITION OF THE ELBOW-JOINT. 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 figs. 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 fur, unless by supposing these cases congenital, namely, the alteration and t elongation of the neck of the radius. “ L’ex- tremité supérieure de chaque radius avait abandonné sa situation naturelle, se trouvait placé derritre l’extremité inférieure de l’hu- merus, et depassait cette extremité d’nn pouce au moins. Cette disposition était ab- solument la méme de chaque cété du corps.” We know of no process which could take lace 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 eases. 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 extremit of the radius; and these were cases in which no doubt could be entertained that they were congenital. isease.-—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- fous 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. 0 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, ae to the outer condyle of the humerus and head of the radius; the supinators arisin ' here are, in severe cases, occasionally elevated _ and thrown out from the bones by a soft tumour, which, upon examination, couveys 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- 17 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 apo the synovial investment of the carti- ages. 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 dct 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 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 ABNORMAL CONDITION OF THE ELBOW-JOINT. 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 coverin 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 ~ eR Fe Megrny Se fa errr reer Vee » ee are, however, in these s ABNORMAL CONDITION OF THE ELBOW-JOINT. 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. When 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 ike matter in their cells; when exam- ined in an earlier stage of this scrophulous caries, these o are generally found to be pre- ternaturally 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 cimens 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- lete 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 theumatic 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 fname, 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 arrow limits; and when we communicate to the joint any of these motions, the patient complains of much pain, and a very remarkable _ ¢repitation 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 79 met with of a very large size, and can easily be felt through the integuments. Sometimes the — membrane of the joint itself is much istended 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- — to be that the cartilages are removed rom 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 ewes td a rough porous appearance, while the cartilage was entirely removed; but in these specimens no ivory 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 and 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 very 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 fimbriz (as they are called) which encircle the neck of the radius, and occupy the different fosse 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 fimbriz 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 mnch 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.) * [ase 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 sa- pination. These movements did not consist in a simple rotation of the radius on its longitu- 4 . ANIMAL ELECTRICITY. ELECTRICITY, ANIMAL.—A _ power, or imponderable agent, possessed by and Gesived from certain living animals, which enables them, independently of the operations of external agents on their structures, ge duce several of the phenomena exhibited by common and voltaic electricity, generated in inorganic matter. 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. Tt 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, &e.; 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 call es 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 eeery, 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- oot extension, which was not complete, but the girl had perfect use 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 fe 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. radius was large, the great sigmath 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 ity of the h us bore so striking a resemblance to the condyles of the femur, when viewed 2 tomer from the li- teal space, that nobody could look at it without observing the striking resemblance in miniature of the humerus to the femur, There were fibrous ‘ a representing the crucial ligaments, and all bres around were yellow and stronger than natural. The annular ligament of the head of the radius was wider than natural bat much Stronger, and accounted for the passing to and fro of this head in ion an pinati 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. 81 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 narke. unimaculata. Risso. marmorata. Ditto. Galvanii. Ditto. Gymnotus electricus. Trichiurus electricus. Malapterurus electricus. Tetraodon electricus. The four species of sre a inhabit various parts of the Atlantic and Mediterranean. They were formerly regarded as constituting one species, (Raia Torpedo, of Linneus;) and now r. John Davy — 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 ae (the Occhiatella of the Italians) Dr. Davy thinks would be better named T. oculata. th pass in Malta under the term Haddayla. The first of these species (T. vulgaris, of Fleming,) occurs on Hoa 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 fifly- 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. 82 Both species (Nagxn of Aristotle and Oppian) are abundant in some parts of the Mediter- ranean, and are frequently brought to the market of Rome. “On 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. e 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 Linneus) 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.t 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 wers, which was taken in the Atlantic Ocean. © 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.{| Tt must be regarded as an extremely interest- * Hist. rerum Nat. Brasil. 1648. + The name Puraqua is used by Condamine in reference to the Gymnotus. ¢ Kirby and Spence’s Entomol. vol. i, 110. Naturgesch. von Chili. 8. 175. Gesch. des Konigr, Chili. S. 63. Treviranus, Biologie. V. 144, ANIMAL ELECTRICITY. 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 Wes duced by a discharge of its electricity. e 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, Réaumur, 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. power. No irritation has ever produced a dis- 7 after death. The intensity of the elec- trica pore 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. e 0 sometimes bears great irritation, _ even Pane p 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 Lacé- “pede and Réaumur 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- recover their electrical energy after a few hours’ rest. The a seems to possess electrical power even in the earliest periods of its existence. Spallanzani relates that he found within a female torpedo two living fcetuses, which gave distinct shocks on being removed ® ir coverings. Dr. Davy, also, once received a sharp although not a strong shock, in extracting feetal fish from the uterine cavities of a dying Sy som ___ 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- ppved. The torpedo discharges whenever it is _ taken out of the water; and Walsh found that _avvigorous fish repeats the discharge as often as it is lifted out, and again on being re-im- eeeesed 5 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 onducting 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- ated in two glasses filled with water placed at a considerable distance from each other. Whilst the — remained in this state, and tion was of course interrupted, the animal did not to exercise his ower, but whenever any conducting substance d the interval, and rendered the circle ete, it instantly approached the wires, arranged itself, and gave the shock. The same fish, according to the observations of Messrs. Humboldt and Bonpland, ap _ to have the power of transmitting its disc 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- x 83 times rom a single point, at other times from the whole of its surface. Dr. Davy has suatise fied himself that the Torpedo also has the wer of discharging its electricity in any irection it chooses. The shock produced x 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 ceest ihn agitated, and discharges very uently. I. 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 the 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 vel Seal al effects of the dusch IIL. Physiological effects of the discharge.— The efiects. 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 oO causes a momen 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 com 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 G2 84 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 Pelt 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 diferent 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.+ 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 atebb-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. + Phil. Trans. 1773, 467. + Phil. Trans. 1829, 15. The experience of Dr. Davy would lead us to callin 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- ferrible 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 feetal fish. Phil, Trans. 1834 ANIMAL ELECTRICITY. 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 lefta severe pain in his knees and in other parts of his body, which continued for several 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.> 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. Keempfer 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 Malapterurus of 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 hmbs. In attempting to takean 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 (i 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. + Flagg, do. ii. 170. t Ameen. Exot. 514, al le, sem ‘small out giving any evidence of feeling it. ecb: Ssiments of Schilling. Professor H ~ den ANIMAL ELECTRICITY. 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 manife 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 ms attached to long cords. The fishes left in a pool thus disturbed were found searcely 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- map submersion. n this way many mules are destroyed in at- tempting to ford rivers inhabited by the Gymno- tus. Sogreat 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 eevee 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- Galvani, having 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 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 , and adhered to it; and that it became so id when detached from the magnet, that it gave no shock when irritated. Ingenhousz, Wanzani, Flagg, Humboldt, and Bonpland ined no such results in repeating the ee of Ley- that the fish examined by Schilling may have been coated with particles of ferrugi- nous sand, which eo forms the beds of the American rivers inhabited by the Gymnotus; * Mém, de l’Acad, de Berlin, 1770, 85 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 yood 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 yp aya 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.t 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 etic 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 pare eight needles within a spiral, formed of fine copper wire, one inch and a half long,and one tenth of an inch in diameter, containing about one hundred and eighty convolutions,and weighing four 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 an sr pile, and the electricity of the ventral surface with that of the zine plate. In 1827, before Dr. Davy performed his ex- riments, similar magnetic effects were observed b means of the multiplier, by MM. De Blainville and Fleuriau, at La Rochelle. They * Biologie, v. 145. a f + 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 uced on the elec- trometer. Philadelphia Med. and Phys. Journal, i. 15. 86 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 Hum hry 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-+ 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.} 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 platina 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 betweep 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, Elem. de Phys. i. 773. + Phil. Trans. 1829. ¢ Phil. Trans, 1832. § Phil, Trans, 1834, ANIMAL ELECTRICITY. the fish is twelve feet distant from their hands. But Humboldt and Gay Lussac state that th received no shock when they touched the fis 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 Pall (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 ip 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 — 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. VIL. 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 pri 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. Day: has directed his attention particularly to this point, and, although he used active fish, and took * Ann. de Chimie, t, Ixv. 15. ‘ i ANIMAL ELECTRICITY. eve ible precaution, he could neither, in the fob, detect the slightest indications of the 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 omen 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, wi its margin dry, and aoe 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- ture in the motions of the fluid in the air- t meter; 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 mau- 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 the discharge along the metallic sheet, the fish being at the time out of the water. As was very dis- tinetly seen at the margins of the slit. Fahlberg of Stockholm used the same kind of apparatus, but with gold leaves instead of pewter, and ee eas Sek ost @ line apart. . Williamson fixed two brass rods in a frame, Shan get som paraliglliogge 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 di , 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. Rbesrding 10 Mr. Todd, (whose experiments were made on the torpedo at the Cape of Good Hope,) it is 7 to cut through all the nerves going to the electrical organs to destroy * Phil. Trans, 1834, 87 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 ee Mr. Todd’s experiments, Dr. Davy o tained 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 the were connected, the fish, on being irritated, gave a shock to an assistant, who grasped the corresponding electrical o: ase | Spellanzant 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 Miiller 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 ee at remarks = if skeg an opportunity of experimenting on the torpedo, his fet pee tea Thould 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.f 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 Saurus, by several anatomists, and no doubt is entertained that they, together * Phil. Trans. 1816. + Phil. Trans. 1834. 120. ¢ Handbuch der Physiol. des Menschen. Co- blenz. 1833. 88 ANIMAL ELECTRICITY. with their large nerves, are the sole means employed in bringing this mysterious agent under the control of the animal’s volition. They are therefore well worthy of an attentive examination. 1. The electrical organs in the torpedo.— The torpedo is a flat fish, possessing the same general oes paca and structure as the rays, and classed along with them in zoological sys- tems. The electrical organs occupy a large coverings are discovered investing the electrical organs. The outer one has longitudinal fibres, which are rather loosely adherent, and, around the margins of the organs, seem to inosculate with the skin. The inner fascia is of consider- able density, forms the immediate tunic of the electric columns, and sends processes down between them to form their partitions. Through- out their whole extent, the essential part of the electrical organs is formed by a whitish soft Upper surface of electrical organ of left side. A, common iateguments. B, branchial opening. C, eye. D, situation of the gills. EE, 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 abdominal 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 y 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. When 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 gradually diminish outwardly, until, on the external margin, they are only y tits ae q 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 o was 1182. Mr. Hunter found 470 in each organ ina fish of ordinary size. Mr. Hunter described each column as being divided into numerous distinct compart- ments by delicate membranous partitions, laced horizontally, at very short distances m each other. The interstices between them appeared to him to contain a fluid. He found the — 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 ap to him that their number is the same within the same space in all the columns.t 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- vac the column from the fascia.” itions are covered with fine network of arteries, veins, and nerves. According to Hunter, “ they are very vascular.” He described 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 ns fish that had been pati in spirits, by which, doubtless, the elicate membranes were rendered more opaque, and therefore more easily visible.) In point * Phil. Trans. 1773, 481. + Desmoulins and Majendie say that they found 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- neous 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.+ In a memoir on the comparative anatomy of the Torpedo, Gymnotus, and Silurus, Geoffroy described { the columns as being filled with a semifiuid matter composed of gelatine and albumen. A large 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 eet 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. e 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, 1.026, to water as 1.000, while that of a 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 a? 105 grains. © 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 meaee that any muscular tissue enters into their composition. But, in all directions, they are exposed to the pressure of * Phil. Trans. 1832. 259. + Abhandl, der Acad. der Wissensch. in Berlin. $20. 224. ¢ Ann. dn Mus. No. 5. § The smallest torpedo employed by 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 !” 90 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+ 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 pt 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. + 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 ap 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.t The same observer also points out as deserving of sss attention, a very large plexusof nerves ormed 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. + 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 5 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.” a ANIMAL ELECTRICITY. 91 Mi’ The right electrical organ divided horizontally at the place where the nerves enter, the upper half being turned outwards, AA, The first or anterior electrical nerve. BB, The second or middle nerve arising behind the gill. CC, The anterior branch of the third nerve arising behind the second gi 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 fetus 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 Annales du Mas. 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 ning from the abdominal cavity towards the tail, laced one above another with short distances tween 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 ANIMAL ELECTRICITY. another by ees 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 the Gymnotus dissected by'John Hunter,* which was about two feet four inches long, the large The surface of the electrical organs of the Gymnotus, on the right side, after removal of the integuments. a, the lower jaw. 6, the abdomen. c, anus. fin. gg, skin turned back. the small electrical organ. the small electrical organ. space from which the partition is removed. d, pectoral fin. Ah, lateral muscles o i, part of this muscle left in its place. mm, the substance which divides the large organ from the small. Nin i iD CT ng eu i oe i A transverse section of the Gymnotus. a, the surface of the side of the fish. cut ends of the dorsal muscles. cava. cut ends of the two small organs. two organs. b, the anal fin. d, cavity of the air-bladder, e, body of the spine. f, spinal marrow. g, aorta and vena hh, cut ends of the two large electrical organs. k, partition between the e, dorsal surface of fish. ff, anal the anal fin turned back with the skin, to expose kk, the large electrical organ. 1/1, na 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 D 7 Knox, there were thirty-one of these septa.t) 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 aninch. 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 ee, ii, * Phil. Trans. Ixy. 1775. + Edin. Journ, of Science, i. 96, 1824. ore ~ ae Se ban 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 isa 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 ap to be com 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 internal, placed above the muscles. Both or- $s are isolated from the surrounding parts y 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 /ateral line and above the aponeurotic covering of the organ. This aponeurosis is pierced by man holes for the transmission of he nerves, whic are lost within the cellular tissue of the organ. The intercostals supply the inner organ: their electrical branches are numerous and remarka- bly fine.+ The organs of the other known electrical fishes have not yet come under the notice of i anatomist. n 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, a all so as to form a series of separate cells led with a gelatinous matter. But how great is thedifference 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. + Radolphi, (Abbandl. der Acad. 1824.) 140, Je v. Berlin. The organs vary in different fishes; first, in situation relatively to other organs. They bound the sides of the head in the ge 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 incommon. All, for instance, have the skin smooth, without scales, thick, and pierced with small holes, most numerous about the head, and which ur 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.+ 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 Leyden jar. Succeeding observations, however, as we have seen, have shewn that certain differences exist between the phenomena produced hy 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. . nly four of the eight experimental effects enumerated by Dr. Faraday} as characteristic * Mém. de l’Acad. de Paris, 1782. 693. ~ + It is interesting to know that the Arabic name of the torpedo (Rausch) means also lightning. ¢ Philos, Trans. 1833. 94 ANIMAL ELECTRICITY. of common and voltaic electricity are pro- duced by animal ee 3 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 Dr. 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 he laboured to prove by imitating several of the peculiarities of the discharge of the torpedo by a particular arrangement of small Tesien jars, forming a battery, from which the electricity was discharged in large quantity but of low intensity.t 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. + 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, 1855, (Ann, des Sciences Nat, n. s. iv. ,) which seem to have been per- formed with great care. The experimenters com- plesely 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 Jitted 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 organsincommon? 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 H. 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 edhe: bt Treviranus, in 1818, suggested the ikelihood of the power concerned in the ma- nifestation of electrical phenomena by animals, being one of those on which continuance of life in general depends. “ Perhaps,” said he, “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 Carus.[ “ Numerous nerves are distributed upon the cells of the electrical organs, and as it is through the agency of * Philos. Trans. 1828. + Biologie. v. 141. $ Traité clement. d’anat. comp, 2d edit. i. 392. (French translation by Jourdan. ) aed, ee CS Re ST erent | pete 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 theo of the nervous influence being identical wi 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.”+ 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 ch ; 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 The facts, (in addition to those which have chiefly en: 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 tan Y appears to influence powerfully the capil Setulasion. But, shows’ these facts, takes 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. + Discourse on the Study of Nat. Phil. 343. ¢ Syst. der Heilkunde. Wien. 1832, If hypo- such as these should hereafter be proved to — the true state of the case, the electrical ve become objects M23 — interest to the ist, as presenti im with opportunities, a no other po es afford, of studying in accumulation the properties of that wonderfi 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 ied acon 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, Sack Mobi 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 done at different 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 uo certain indication of electricity ob- tained, although the most delicate instruments were used.* Peute's experiments have been repeated by Miiller with the same results. essrs. 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.+ But seeing that the electricity made manifest in this experiment may have been develo 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, | po cagied so called, we must here take notice of the manifestation of common electricity in animal substances and an living animals. The mere contact of heterogeneous bodies is * Journal de Physiol. x. 217. Some years ago M. Pouillet Saneoncel that he had witnessed electrical phenomena during the operation of the are 0} les; but he has since con- ful agent, which is the moving power of the animal organiza- tion, and a very important link in the cosh of _ auses and effects by which life is manifested. fessed that he was deceived. + Edwards, De l'influence des 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, na 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 becehe 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. (Keemtz.) When two rsons, both insulated, join hands, electricit; 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 they 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 hy 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 Menschen. 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. Cateris 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 economy, we cannot but conclude that, in the course of the many interchanges that are constantly taking pave amongst the component particles of all iving 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 y b means of Volta’s electrometer, used along wi a condenser, but always failed to perceive any indications of free electricity while he was entirely naked. It was also imperceptible while he perspired freely, and when his clothin was cold. Under other circumstances, he foun 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 obaaed 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.+ 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 bien 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 * Physiol. transl. by Drs. Gully and Lane, 276. + Meckel’s Archiv, iii. 161. vom py we ANIMAL ELECTRICITY. 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 gegen negative than thatof 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 Ratings it again increases. Gardini found that the electricity of women during menstrua- tion and pregnancy is negative. Some Tndividuals 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 Bea It is related of a certain monk that s 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 toa second experiment.” In repeating ees eorerinent, we have obtained the like result. Weare not aware ofany other observer having met with any thing resembling an accumulation of electricity in quadrupeds, excepting Cotugno, who asserted that, in dissecting a living mouse, he felt an electric shock when its tail touched his finger.+ XI. 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 di 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,t that the electrical organs communicate to the fish eptions 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 gereizte Muskel-und- £ Nervenfaser. Berlin, 1793. i. 30, ; + Bridgewater Treatise, i, 31. VOL. Il. 97 to light and sound. Such tions we can 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 a 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 notus 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 pur 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 eut 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) = J. ae — ears ago.t He says, “ Without denying that the cates may paar that which it disables by the shock, I conceive that the principal use of this power has a reference to the functions of * Phil. Trans. 1835. t Linn. Trans. xiv. 89, 98 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 -oiae also from the fact, reported by Dr. vy 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. Galvani, Dell’ uso e dell’ at- tivita dell’ arco conduttore nelle contrazioni dei moscoli, Bologna, 1794. Ejus. Memorie sull’ elettricita animale, 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 Elettricitat und Reizburkeit. Leipzig, 1795. Humboldt, Versuche iiber die ge- reizte Muskel und Nervenfaser. Berlin, 1797. Treviranus, Biologie. Tiedemann, Physiologie. Miiller, 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. Ingenhousz, Phil. Trans. 1775. Hunter, Phil. Trans. t. Ixiii. etlxv. Geo, Saint Hilaire, Ann, du Mus. t. i. Ei , Recueil 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, Traité d’Elec~ tricité 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.” NDOSMOSIS. ENDOSMOSIS, (edov, intus, woos, 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 eame 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 ececa 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 ewca permeated their coats, and were diffused in the surrounding water. I saw, further, that two opposite currents were established through the parietes of the ceca; the first and stronger formed by the exterior water flowing towards the fluid contained in the ewca; 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 Exosmosis. These titles, I must allow, are objectionable, and perhaps badly chosen. The first conveys the idea of an entrance and the second of anexit. 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. cending branch containing a column of mer- cury, which was raised by the interior fluid of the endosmometer in proportion as the en- dosmosis increased the volume of this fluid.* By means of these two instruments I have found that the velocity and strength of endos- mosis follow exactly the same law. Both are in 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, syru of which the density is 1.1, and syrup of whic the density is 1.2, and in plunging in both eases 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 the exgesses of density of the two solutions of sugar above the density of ; water, which is 1. I have ascertained by ex- ee eee eee 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 ordi density,) you would obtain an endosmosis, the strength of which would be capable of raising water more than 150 feet. uids of a different nature have, with refer- ence to endosmosis, properties which are in no Way in proportion to their respective densities. us Sugar-water and gum-water of the same density, being put successively into the same osmometer, 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 enddsmosis 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- nable, and I am persuaded that if 1 have ever obtained a different result, the experiment has been defective. _ Ihave made several experiments since with I s and albuminous waters placed suc- cessively in the same endosmometer, surround- ed with pure water, which produced endos- ™osis severally in the proportion of 1 to 4; 80 that the albumen had four times more power of endosmosis than the gelatine. I have seen __* See my work entitled, Nouvelles Recherches sur Vendosmose et ’exosmose, &e, 8vo. Paris, 1828, 99 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, dr 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 late of baked clay instead of the animal mem- ro the endosmosis which a saline solution roduces, 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 ma: 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, &e. 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 spss carbonatée) reduced to thin lamine, and employed to close an en- dosmometer, is totally without the power of roducing endosmosis; my latter experiments somewhat modified this conclusion. After having vainly employed Jamine 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 instrament 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 H2 100 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 mite 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 mo 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. I 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. I 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. I 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 lamine 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- ENDOSMOSIS. 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 (grés) 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 , close-grained and very little permeable to uids. 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. I 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 pace of the voltaic pile in the experiment of M. Porret, heart: 9 in the Annales de Chimie, 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. Having 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. of the endosmometer communicate with the negative pole of the pile, and the exterior I made the interior water — ENDOSMOSIS. 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 neous nature of fluids. It was in vain, however, that I tried to discover signs of this electricity with the most delicate electro- 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 preducing heteroge- neousness of quality in the two fluids subjected __ to the positive and negative poles. Experience f 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 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- ness of quality in two fluids, separated . a membranous partition, occasions the phe- nomenon of endosmosis. Upon this point inions are greatly divided. M. Poisson and r. 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 inte! be- tween the two fluids. In this explanation the enon of the current of exosmosis is set , or ed 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- ity 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, 101 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 um towards that of the sugar; in other words, m 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 the 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 1.014,) 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. Witha temperature of +70 cent. I found that fifteen centilitres of pure water through a capillary tube of glass in one undred 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 hundred 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 sugar, 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 just mentioned ; and finally, that the viscidity of the gum-water, containing two 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 1 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 gommé ) or silk covered with a layer of caoutchoue, 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- dosmotie 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 water athwart the septum of caoutchouc is ac- companied by a counter-current, which carries the water towards the alcohol through the same septum. [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, (affinité de mixtion) and enables it to penetrate the substance of the caoutchouc, which denies all access to water when it is pure. Itis 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, ENDOSMOSIS. a considerable quantity of water remained, whilst the alcohol, previously to being so em- loyed, burned away entirely, leaving no water hind 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- tea that a measure of salt water is separated rom 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 — 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. Aleo- 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 aleohol 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 — ‘i aS ENDOSMOSIS. in silence all the proofs that seem to establish this theory upon a basis of sufficient solidity ; for I cannot but pares 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- a 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 ores 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 remy tubes made of different mate- rials, ese 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 ae of different densities, and to compare the power of capi ascent sessed by each of these wi belles oan 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 103 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 toone. 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 R. (50 Fahrenh.) I found that the same tube, at the same tem- perma raised to 6} lines the solution of ydrochlorate of soda, the density of which was 1.12, and that it raised to 94 lines the solution of the same salt, the density of which was 1.06. 1. The capillary ascension of the water being ......... peal The capillary ascension of the most dense fluid being .......+e005-- Gf cvveertece 12 The excess of the capillary ascension CU WHEL IS 2 cwccdesinswsaeswedn: OOF 2. The capillary ascension of water DEING civicdsatevccerecvevce- coe 12 The capillary ascension of the least dense saline solution being ....-- 9§ The excess of the capillary ascension Of. WALEE IS sccccsiscececsosceeee, 2 Thus the two excesses of the capillary ascen- sion of water above the capillary ascension of each of these saline solutions are 5] and 2j, or 46 and 2g, 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 in therelation of 2 to 1. Shall we refer this result to the 104 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 to1? 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 Aeydrochtoekae of soda, having the same density 1.085, and tested their ca- pillary ascension in the same tube in which we ave 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 ENDOSMOSIS. 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 ber pee 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 pte | canals, and that consequently this double movement of transmission takes place by a reciprocal penetration of the two fluids. e 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 etledeulphiais acid, under the same circum- stances as the acids mentioned above, gradually to sink in the tube of theendosmometer. I con- cluded from this that these acids did notoccasion 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 ———— i t t 5 ENDOSMOSIS. and hydrosul phuric 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 cts simple gum-water constantly does. These 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 in water, I found the acid fluid sink rapidly in the tube, and flow towards the inferior water, making its way by filtration through theanimal membrane. I then reversed arrangement observed in this experi- ment. I filled the endosmometer with water, and plu the reservoir into a solution of oxalie acid. 1 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, was the current of endosmosis directed from the acid towards the water. The follow- ing are the iculars of this experiment. Having poured some rain-water into the reser- voir e 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 dually 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- | seen the same experiment a third time, filling 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- 105 tion of oxalic acid as before. I reduced the density of the exterior acid solution to 1.01, but the included water still gave evidence of a pretty active endosmosis. 1 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 weaker 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 msm 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 inoistened 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 appl this membrane to an en- dosmometer, whic Tal 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 instrament 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 ual 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 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 ——— 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 animal 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- juble 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 ENDOSMOSIS. of 1.05, at a temperature of -- 25° cent. it exhibits no obvious endosmotic phenomena whatever; not that there is not reciprocal 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 ata temperature of -+- 25° cent. These facts induced me to imagine that if the oxalic acid alone presented the endosmotie 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 + 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 scalehigher. 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. Ata temperature of 8$° cent. the solution of tarta- ric acid, of the density 1.1, was no longer the solution of mean density dividing the two opr 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 - simple capillary filtration. ENDOSMOSIS. sought for in a more dense solution of tartaric id, 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 4th 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. In 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 +4- 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 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 po water bya es of an animal membrane. t may be as well if I here state that when a solution of one part of nitrate of potash in three oe of water was separated by a piece of der from pure water, I have always ob- served the endosmotic current directed towards the solution; the temperature might be at zero, or + 10°, ss Fe, the same phenome- non always occurred. This is sutticient to prove that endosmosis is governed by laws en- tirely different from those that ide over I add, that the solution of tartaric acid, of 1.105 density, hav- * Mém. de l’Acad. des Sciences, 1816, 107 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, bas 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 -F 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 ex riment, as in the one detailed immediately * Nouv. Recherches sur l’Endosmose, &e, p. 25. See also my Memoir in the 49th vol. of the Annales de Chimie, p. 415. 108 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 moderate 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 itis 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 4+ 4° and +4 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, es 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. ENDOSMOSIS. 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. Ata tempe- rature of -- 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- erature causes the mean term of the density of ydrochlorie 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 arborescens, 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 —— pe eh) aegis - iY ENDOSMOSIS. 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 ata 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 Se saat from -}- 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. a 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 + 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. I was anxious to see what endosmotic effects it would produce with an endesmometer 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- 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- ity of 1.0549, exhibits the same phenomena as acid when separated from water by a lamina of baked clay : it first occasions en- 109 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. Hydrosulphurie 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 hydrosulphurie 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 omer endosmosis in the opposite direction. ere 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 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 mavens 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 antayonist 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. Tnto 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 ENDOSMOSIS. 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 a to be: 13. A dotipronal action Setereon tothe 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. A 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 cireum- 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 ie ccsbeonies its very energetic ascending motion. have also shown that all the spontaneous mo- tions of vegetables are referable to endosmosis. The organic vegetable tissue is composed of a yl ENTOZOA. 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 ne mena take place among the various cells and cavities exhibited by the organism of animals. rig the effects of endosmosis, its influence on e physiological phenomena presented by ani- wel Ras sr ve aseraninel) and re 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, (evroc, intus, Qwoy, animal,) Wes or, ob, erpsybes TAaTUA, arxa- s, Arist. et Antiq. Vers Intestinaur, Cuv. elmintha, Splanchnelmintha, Zeder. The term Ewnrozoa, 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 ites, 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 nee 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. it may be further observed that as the members of no single class of animals are con- fiued to one particular country, so neither are the different natural groups of Entozoa exclu- sively represented 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 Planaria from the Trematoda, or the Vibrionide from the microscopic parasite of the ae gman ie n 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 ee ene, mere mesh. the groupe. 0 spoken of, they will be denominated Protel- mintha, Sterelmintha, and Calelmintha respec- 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, 111 and more or less accurately defined by pre- vious zoologists. After the dismemberment of the Infusoria of Cuvier into the classes Polygastrica and Rotifera, 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 Cercariade and Vibrio- nide. 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 Vibrionide should subsequently have been detected in the human body itself. Premising that the tribe Vibrionide 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 Cercariad@, in which the generative apparatus is equally inconspicuous; and these ilies, 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 ‘ Régne Animal’ of Cuvier, and which are there respectively denominated ‘ Vers Intesti- naux Parenchymateux,’ and ‘ Vers Intestinaux Cavitaires.’ e 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 distine- tion of each group as Latin equivalents for the compound French phrases by which they have hitherto been designated. EAays¢ appears to have been applied by the Greeks to the in- testinal worms generally, as Aristotle speaks of sAusbes wAareses, intestinalia lata, and rAuswbes orgoyyvAas, intestinalia teretia. In framing the terms Sterelmintha and Calelmin- tha, from sAysrs oregex, a solid or parenchy- matous worm, and sAjsvs xosAn, a hollow or cavitary worm, I follow the example of Zeder, and omit the aspirate letter. It may be ob- served by the way that Zeder’s term Splanchnel- mintha, besides including animals which are developed in other parts than the viscera, is, like the term Entozoa, open to the objection of being applied to a series of animals which, ac~ cording to their organization, belong to distinct classes. The limits and object of the present article obviously forbid an extensive or very minute consideration of the anatomical details of each of these classes of animals, and we are com- pelled to confine ourselves almost exclusively to such illustrations of their respective plans of organization as are afforded by the — referrible to each which inhabit the human body. If a drop of the secretion of the testicle be expressed from the divided vas deferens in a recently killed mammiferous animal, which 112 has arrived at maturity, and be diluted with a little pure tepid water and placed in the field of a microscope, a swarm of minute beings resembling tadpoles will be observed moving about with various degrees of velo- city, and in various directions, apparently by means of the inflexions of a filamentary caudal appendage. These are the seminal animalcules, oosperms, or Spermatozoa (fig. 51): and, as it is still undetermined whether they are to be regarded as analogous to the moving filaments of the pollen of plants, or as independent or- ganisms, it has been deemed more convenient to consider them zoographically in the present article as members of the class Entozoa. The body to which the tail is attached is of an oval and flattened or compressed form, so that, when viewed sideways, the Zoosperm appears to be a moving filament like a minute Vibrio. It is this compressed form of the body which principally distinguishes the Sper- matozoa or seminal Cercarie, from the true Cercarie of vegetable infusions, in which the body is ovoid or cylindrical; the caudal ap- pendage of the Spermatozoa is also propor- tionally longer than in the Cercarie. In some species of the latter genus an oral aperture and ocelliform specks of an opake red colour have been observed on the anterior part of the body, and they manifest their sen- sibility to light by collecting towards the side of the vessel exposed to that influence. In the Zoosperms, which are developed exclu- sively in the dark recesses of animal bodies, the simplest rudiments of a visual organ would be superfluous; they are, in fact, devoid of ocelli, and even an oral aperture has not yet been detected in these simplest and most mi- nute of Entozoa. In neither the Zoosperms nor the Cercarie has the polygastric struc- ture been determined. On the contrary, some of the non-parasitic species, as the Cercaria Lemna, are stated to have ‘a true alimen- ne Sayed not polygastric.’* he Spermatozoa are not, however, the only examples of the present order of Protelmintha which have their habitat in the interior of living animals; many of the Entozoa themselves have been observed to be infested by internal para- sites, which are referrible by their external form tothe Cercariade. Although no distinct organs of generation have been detected, there is reason to suspect that the Spermatozoa are oviparous: they are also stated to propagate by spontaneous fission ; the separation taking place between the disc of the body and the caudal appendage; each of which develope the part required to form a perfect whole. The Zoosperms of each genus of animals present differences of form or proportion, and frequently also differences of relative size as compared to the animal in which they are deve- loped ; thus, in the figures subjoined, which are all magnified in the same degree, the Zoosperm from the Rabbit is nearly as large as that from the Bull, (fig. 51.) * Pritchard’s Animalcules, p. 184. ENTOZOA. Fig. 51. They ap to be o~~- formed in ary seminal eee rae under similar Ee aws to those which "SS side over the devalbits Man. ment of other Entozoa in the mucous secretion of the Intestines, &c., but are more constant in their — existence, and must there- fore be regarded as fulfil- ling some more important oftice in the economy of the animal in which they Bull. exist. ———————gp_, They are not found in A the seminal passages or > glands until the full Rabbit. riod of puberty; and in some cases would seem to be periodically deve- loped. In the Hedgehog Sparen. and Mole, which exhibit a periodical variation in. Y= the size of the testes ina well-marked degree, the Spermatozoa are not ob- servable in those glands during their state of quiescence and_ partial es Professor Wag- ner®* examined the testes of different Passerine Birds in the winter sea- son, when those bodies are much diminished in size. (See vol.i. p.354, Jig. 183.) They then con- tained only granular sub- stances, withouta trace of the Spermatozoa. When the same bodies were ex- amined in spring, they were found to contain spherical granules of dif- ferent sizes and appear- ances, (A, B, fig. 52,) which led to the suppo- sition that they were the ova of the Spermatozoa in different stages of deve- lopment, and capsules containing each a nume- rous group of Sperma- tozoa (C) were also pre- sent; whence it would appear that many of these animalcules were deve- loped from asingle ovum. In the semen contained in the vasa deferentia the Spermatozoa (D) were in great numbers, having escaped from their cap- sules; they exhibit a re- markable rotation on their * Miiler’s Archiv. 1836, Development of Sper- P+ 225. matozoa, Bunting. OO ENTOZOA. axis, which continues for five or ten minutes after the death of the bird in which they are developed. Some have sup that these animalcules were the result of a putrefactive process, but this is disproved by their presence in testicles which have been removed from living animals, and by their ceasing in fact to exist when the seminal secretion begins to undergo a decom- position. Their extraordinary number is such that a drop of semen appears as a moving mass, in which nothing can te distinguished until it has been diluted as before-mentioned, when the animalcules are seen to disengage them- selves and commence their undulatory move- ments. By means of the continual agitation thus uced the chemical elements of the fecundating fluid are probably kept in a due state of admixture. By the same movements the iipregmating influence of the semen may be carried beyond the boundary which it reaches in the female organs from the expulsive actions of the coitus. It has been conjectured that from the rapid and extensive multiplication of these animalcules they may contribute to pro- duce the stimulus of the rut. But the con- sideration of the part which the Zoosperms may play in generation belongs to the Physio- logical history of that function, and would lead to discussions foreign to the present article, which treats of their form and structure simply as the parasites of animal bodies. In the human subject the form cn the Zoo- s is accurately represented in fig. 51. a aie the cold-blooded Reptiles the Zoo- sperms of the: Frog (fig. 51) have been ex- amined with most attention, and have been the subject of interesting experiments in the hands of Spallanzani and Dumas. The milt or developed testicle of the osseous Fishes abounds with moving bodies of a glo- _ bular form. In the Shark and Ray the Zoo- _ Sperms are of a linear and spiral form. The molluscous animals are favourable sub- jects for the examination of the present tribe of Entozoa on account of the great relative size of the parasites of the seminal secretion. They are mostly of a filamentary form, and have long been known in the Cephalopods. The Zoosperms of the Snail ( Helix Pomatia ) _ present an undulated capillary body, and move Sufficiently slowly to permit their being readily _ followed by the eye. The Spermatozoa have been detected and described in the different classes of the Arti- culate Animals. In Insects they are of a fine capillary form, and are generally aggregated in bundles. They abound in the semen of the Anellides and Cirripeds; lastly, these parasites have been found to exist in vast numbers in the _ Spermatic tubes of the higher organized En- those 5 cies which are _ These animalcules are termed Vibrionide from tozoa themselves. _ The second tribe of Protelmintha includes lindrical, filiform, eel-like, microscopic cules which abound in decayed vege- table paste, stale vinegar, &c. together with others which have attracted particular attention by the destructive waste caused by certain s parasitic on living, vegetab es. VOL. II. 113 their darting or quivering motion. They differ from the polygastric Infusories, not only in the absence of internal stomachs but also of external cilia, which is inferred by their not exciting any currents when placed in coloured water. They present a higher grade of organi- zation than the Cercarian tribe in the presence of a pene alimentary canal, which is re- markably distinct in some of the higher forms of the group, as the Gordioides and Oxyu- roides of Bory St. Vincent. The higher ee Vibriones have distinct erative organs, and are ovo-viviparous. ie the species of Vibrio which infests the grains of wheat and occasions the destructive disease called Ear-cockle or Purples, Mr. Bauer found the ova arranged between the alimentary canal and the integument, in a chaplet or moniliform oviduct which terminated by a bilabiate orifice at a little distance from the caudal extremity of the body. The ova are discharged at this orifice in strings of five or six, adhering to each other. Each egg is about stoth of an inch long, and ith or sith in di- ameter: and they are sufficiently transparent to allow of the young worm being seen within: and the embryo, in about an hour and a half after the egg is laid, extricates itself from the egg-coverings. Of the numerous individuals examined by Mr. Bauer, not any exhibited external distinctions of sex, and he believes them to be hermaphrodites. In the Anguillula aceti, or common Vinegar- eel, Bory St. Vincent has distinguished indi- viduals in which a slender spiculum is pro- truded from the labiate orifice corresponding to that above described from which the ova are extruded ; these individuals he considers to be males; they are much less numerous than the females; are considerably smaller ; and the internal chaplet of ova is not dis- cernible in them. In the female the ova are arranged in two series on each side of the alimentary canal, and the embryo worms are usually seen to escape from the egg-coverings while yet within the body of the parent, and to be born alive. Ehrenberg figures the two sexes of Anguillula fluviatilis in his first trea- tise on the Infusoria (tab. vii. fig.5.*) The granular testis and intromittent spiculum, which 1s single, are conspicuous in the male; the ova in the female are large and arranged as in Anguillula aceti. Such an organization, it is obvious, ‘closely approximates these higher Vibrionide to the nematoid Entozoa, as the Ascarides and Oxyuri, and further researches on this interesting group will doubtless lead to the dismemberment of the Oxyuroid family from the more simple Vibrionide, as the genera Bacterium, Spirillum, and Vibrio, with which they are at present associated. To the group composed of the three last- named genera, the microscopic parasite of the human muscles, termed Trichina Spiralis, is referrible.+ , “ Organisation, systematik und georaphisches Verhiltniss der Infusionthieschen, 1630. + Zool. Trans. vol. i. p. 315, and Zool. Pro- ceedings, for February, i835. I 114 This singular Entozoon I discovered in a portion of the muscles of a male subject, which was transmitted to me for examination, at the beginning of 1835, by Mr. Wormald, Demon- strator of Anatomy at St. Bartholomew’s Hos- pital, on account of a peculiar speckled ap- pearance of those parts. This state of the muscles had been noticed by that gentleman as an occasional but rare occurrence in subjects dissected at St. Bartholomew’s in several pre- vious years. ) “ The portion of muscle was beset with minute whitish specks, as represented in the subjoined cut (fig. 53): and in fourteen subsequent instances which have come to my knowledge of the presence of this entozoon in the human subject, the muscles have presented very similar appearances. The specks are produ- ced by the cysts con- taining the worm, and vary, as to their dis- tinctness, according to their degreesofopacity, whiteness, and hard- ness. The cysts are very readily detected by gently compressing a thin slice of the infect- ed muscle between two pieces of glass and ap- plying a magnifying power of an inch focus. They are ofan elliptical figure, with the extremi- ties more or less attenuated, often unequally elongated, andalways more opaque than the body or intermediate part of the cyst, which is, in general, sufficiently transparent to shew that it contains a minute coiled-up worm. The cysts are always arranged with their long axis parallel to the course of the mus- cular fibres, which probably results from their yielding to the pressure of the contained worm, and becoming elongated at the two points where the separation of the muscular fasciculi most readily takes place, and offers least re- sistance; and for the same reason one or both of the extremities of the cyst become from repeated pressure and irritation thicker and more Opaque than the rest. ‘That the adhesive process in the cellular tissue, to which I refer the for- mation of the cyst, was. most active at the extremities of the cyst is also evinced by the closer adhesion which these parts have to the surrounding cellular+tissue. The cysts measure generally about th of an inch in their longitudinal, and ;};th of an inch Cysts of the Trichina Spiralis in situ, natural size. Fig. 54. A separate Cyst _ of the Trichi- na. whichis in their transverse diameters : as 2 like other cysts which are the vai result of the adhesive inflamma- i. tion, they have a rough exterior, and are of a laminated texture. ENTOZOA. The innermost layer (fe. 54), however, can sometimes be detached entire, like a distinct cyst, from the outer portion, and its contour is generally well marked when seen by trans- mitted light. By cutting off the extremity of the cyst, which may be done with a cataract needle or fine knife, and gently pressing on the opposite extremity, the Trichina and the granular secre- tion with which it is surrounded, will escape ; and it frequently starts out as soon as the cyst is opened. But this delicate operation requires some practice and familiarity with microsco- ar dissection, and many attempts may fail efore the dissector succeeds in liberating the worm entire and uninjured. When first extracted, the Trichina is usually disposed in two or two and a half spiral coils : when straightened out (which is to be done with a pair of hooked needles, when the sur- rounding moisture is so far evaporated as that the adhesion of the middle of the worm to the glass it rests upon shall afford a due resistance to a pressure of the needle upon the extremi- ties), it measures jth of an inch in length and qioth of an inch in diameter, and now requires for its satisfactory examination a magnifying power of at least 200 linear admeasurement. The worm (fig. 55) is cylindrical and fili- form, terminating obtusel at both extremities, whic’ are of unequal sizes; taper» ing towards one end for about one-fourth part of its length, but continuing of uniform diameter from that point to the opposite ex- tremity. Until lately it was only at the larger extremity that Ihave been able to distine guish an indication of an orifice, and this is situated in many specimens in the centre of a transverse, bilabiate, linear mouth, (u, fig. 54.) A recently extracted living worm, when ex- amined by a good achromatic instrument be- fore any evaporation of the surrounding fluid has affected the integument, presents a smooth Ss Trichina spiralis mugnified. * transparent exterior skin, inclosing apparently a fine granular parenchyma. It is curious to watch the variety of deceptive appearances of a more complex organization which result from: the wrinkling of the delicate integument. I have sometimes perceived what seemed to be a sacculated or spiral intestine; and, as eva- poration proceeds, this has RL been surrounded by minute tortuous tubes; but the fallacy of the latter ap) nce is easily de- tected. A structure, which I have found in more recent and better preserved specimens than those which were the subjects of my first: description, is evidently real, and may pro- bably belong to the generative system of the Trichina ; it consists of a small rounded cluster of granules of a darker or more opaque nature than the rest of the body; it is situated about one-fifth of the length of the animal from the larger or anterior extremity, and extends about. half-way across the body. J : : 7 ENTOZOA. Dr. Arthur Farre, whose powers of patient and minute observation and practised skill with the microscope, are well known to those who have the pleasure of his acquaintance, discovered, by theexamination of recent Trichin under favourable circumstances, that they pos- Sess an intestinal canal with distinct parietes. He describes it as commencing at the large end of the worm, bounded by two parallel but slightly irregular lines for about one-fifth of the length of the body, and then assuming a sacculated structure which “ becomes gradually lost towards the smaller end where the canal assumes a zig-zag or perhaps — course, and at length terminates at the small end.’”’* In a recent examination of some Trichine from an aged male subject at St. Bartholomew’s Hospital, I perceived a transverse slit close to the small extremity on the concave side, which I regard as the anus. The muscles which are affected by the Tri- chine are those of the voluntary class; and the superficial ones are found to contain them in greater numbers than those which are deep- seated; the pectoralis major, latissimus dorsi, and other large flat muscles usually present them in great abundance. They have been detected in the muscles of the eye, and even in those belonging to the ossicles of the ear, and of whose actions we are wholly uncon- scious: they also occur in the diaphragm, in the muscles of the tongue, in those of the soft palate, in the constrictors of the pharynx, in the levator ani, in the external sphincter ani, and in the muscles of the urethra. But they have not yet been detected in the muscular tunic of stomach and intestines, in the detrusor urine, or in the heart. It is an inte- resting fact that all the muscles infested by the Trichina are characterized by the striated ap- pearance of the ultimate fasciculi: while the muscles of organic life, in which they are absent, have, with the exception of the heart, smooth fibres, not grouped into fasciculi, but reticularly united. From the instances of this parasitical affec- _ tion of the human body which have already been recorded, and from other unpublished cases in which I have examined the worms, it is evident that their presence in the system is unconnected with age, sex, or any particular form of disease. have been found in the bodies of persons who have died of cancer of _ the penis; tubercles in the lungs; exhaustion of vital by extensive external ul- ceration of the leg; fever combined with tu- bercles in the lungs; aneurism of the aorta; sudden depression of the vital powers after a comminuted fracture of the humerus; diar- The cases which had occurred before the lication of the first description of this tozoon led me to conceive that, although the * Species was of so minute a size, yet the num- ber of individuals infesting the body was so immense, and their distribution through the muscular system so extensive, that they might * See Medical Gazette, December, 1835. 115 eccasion debility from the quantity of nutri- ment required for their support; and I ob- served “ that it was satisfactory to believe, that the Trichine are productive of no other con- sequences than debility of the muscular system; and it may be questioned how far they can be demnidered as a primary cause of debility, since an enfeebled state of the vital powers is the probable condition under which they are originally developed. No painful or incon- venient symptoms were present in any of the above-mentioned cases to lead the medical attendants to suspect the condition of the mus- cular system, which dissection afterwards dis- closed : and it is probable that in all cases the patient himself will be unconscious of the presence of the microscopic parasites which are enjoying their vitality at his expense.”* Since writing the above, a case has occurred in which the Trichine were met with in the muscles of a man who was killed while in the apparent enjoyment of robust health by a frac- ture of the skull. I received portions of the muscles of the larynx of this individual from my friend Mr. Curling, Assistant-Surgeon to the London-Hospital, who has recorded the case in the Medical Gazette, and the worms were similar in every respect to those occurring in the diseased subjects. The deduction there- fore of the development of the Trichina bein dependent on an enfeeblement of the vita powers is invalidated by this interesting ex- _ ving now the consideration of Entozoa, which from their minute size and organization would have ranked with the vast assemblage of animalcules which are collected under the head Infusvria in the Régne Animal, we come next to the consideration of the animals which form that scarcely less heterogeneous class, the Entozoa of Rudolphi. These are distributed by that Naturalist into five orders, which may be synthetically arranged and characterized as follows. Orpo I. Cysrica, Rud. (xverss, vesica.) Vermes vesiculares, Blasenwiirmer, Cyst-worms or Hydatids. Char. Body flattened or rounded, conti- nued posteriorly into a cyst, which is sometimes common to many indivi- duals. Head provided with pits (bo- thria two or four) or suctorious pores (four), and with a circle of hooklets or with four unarmed or uncinated tentacles. No discernible organs of generation. Obs. This order is not a very natural one; the species composing it are closely allied to the Tape-worms in the structure of the head, and when this is combined with a jointed structure of the body, as in the Cysticercus fasciolaris common in the liver of Rats, the small caudal vesicle forms but a slight ground for a distine- tion of ordinal importance. The Cystica of Rudolphi form part of the Order Tenioidea of Cuvier; and may be regarded as representing * Zoological Transactions, vol. i. p. 315. + Zool. . vol, i. p. 323, 12 116 the immature states of the higher orders of Sterelmintha. Orvo II. Crsrorpea, (xeoros, cingulum, erdos, forma. ) Vermes_ tanieformes, 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 Ligule, with simple heads un- provided with bothria or suckers; a conjunc- tion which detracts from the natural character of the group. Cuvier separates the Ligule from the Tenia, 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 Ligule found in the intestines of Birds; and respecting which Rudolphi hazards the theory that they are the more simple Ligule of Vishes, 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. Orvo II. Trematona, (renpa, foramen, Ten atwdns furaminosus. ) Vermes suctorii, Saugwirmer, 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 Planari« of Muller, (fig. 80.) Rudolphi, who seems to have sup- posed the Plunurie to be of a more simple organization than they truly possess, approxi- mates them to the Ligulz or T artigubased Ces- toidea. Other naturalists, unwilling to asso- ciate the Plunarie 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. Orvo IV. Acantnocrepuata, (axavba, spina, xeParn, caput.) Bandwiirmer, Vermes _uncinati, — Hacken-wiirmer, Hooked-worms. Char. Body elongated, round, sub-elas- tic. Head with a retractile proboscis armed with recurved spines, (fig. 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. ENTOZOA, They abound in the lower animals, and present great diversity of form, some being cylindrical and others sacciform. Orvo V. NemarTorpeE, (vnc, filum, esdos, Vermes teretes, Rund-wiirmer. Round- worms. Char. Body elongated, rounded, elastic. Mouth variously organized according to the genera. A true intestinal canal terminating by a distinct anus. Sevres 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 system 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 intestinaua parenchymateur. 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 Lernwan parasites of Fishes, although they agree with the Nematoidea and all inferior Entozoa in the absence of distinct piesa organs, yet the ciliated natatory members whic 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, Porocephalus, and Syn- amus, which, under the habit of Cestoid or rematode 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 Calelmintha. 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 congeneri¢ forms, under the name of * << Corpus teres elasticum, tractus intestinalis hine ore, illinc ano terminatus. Alia individua mascula, alia feminea,”— . Entoz. p. 3. bl ie lel : i ? t duct? at ENTOZOA. 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 — of the class generally. e first and simplest ite which de- mands our attention is the common globular = aed 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. siderable 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- ote of condensed albuminous matter, of a inated 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 — 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 a i constitute the green matter of ly; (Protococcus viridis, Agardh;) or those equally simple but differently coloured ns iarig, 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 i their kind by gemmules developed external surface of the parent. Or shall we, from the accidental circum- stance of the al being develo; in the interior ‘of timel badien, regard es Rudolphi would , in the same light _ as an ulcer, or pustule,—as a mere morbid pro- The reasons assigned by the learned Pro- 117 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 lace 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- 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 lamine. 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, 6 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 Acephalocystis exogena by Kuhl. 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 ing the armed and suctorious head characteristic of the Canuri and Cysticerci. It must be ob- served that Rudolphit does not ascribe this * Mihi, quidem, ea tandem hydatis animal vivam vocatur, que vitam propriam degit nti Cys- ticerci, Ceenuri, &c. Qux autem organismi alieni v. c. humani) particulum efficit animal, me jadice, dici nequit. Mortua non est, quamdiu organismi partem sistit, uti etiam ulcus, pustula, jorescentia ; oa ideo non sunt animalia.— Fig. 56. . Sahnnt + Vermiculi ¢ bglobosi, jonyo pean dati, etc.; pro ite plus minus vel exserto ve! versions sa = J ronteai i, mox obtusi, mox acuti. Corona uncinulorum, uti videwur, duplex. 118 complicated structure to the vermiculi of the Haman 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, &e. ; The Echinococcus hominis, (fig.57,) which occurs in cysts in the liver, spleen, omen- tum, or mesentery, 1s 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 Elninto- grafia humana of Delle Chiaje. Fig. 57. Echinococcus hominis. Fig. 58. Vermiculi of Echinococcus hominis, highly magnified. Miiller* has recently described a species of Echinococcus voided with the urine by a young man labouring under symptoms of renal disease. The tunic of the containing cyst was a thick white membrane, not naturally divided into lamin; the animalcules 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 them 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 suctoria quatuor; an hec inomnibus? Ipse saltem in suis Echinococcis non vidi, sed dum Be- rolini recens examinarem, microscopio solito et bono destitutus eram.—Hist. Entoz. * Archiv fur Physiol. (Jahresbericht), 1836. ENTOZOA. 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 poles by the retraction of part of the body. 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 animalcule between plates of glass, a group of long, slen- der, straight, sharp-pointed spines became vi- sible within the ody, 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 Teniz. But as this cystic genus, denominated Canurus, (xosvos, communis, ovgc, 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, (xvorss, vesica, xspxos, 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. Sfusciolaris, Cyst. fistularis, Cyst. longicollis, 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 cellulose. | | eye » ENTOZOA. bits a portion of muscle thus infested; a the adventitious cyst laid open, ek the Hy- datid; a’ the adventitious cyst elongated by the extension of the head and neck of the inclosed hydatid 6 in the direction of the muscular fibres. é cysticercus itself sometimes attains the size exhibited in fig. 60, in which a indicates the Fig. 60. Fig. 61. @ 9 Magnified head of Cysticerus cellulose. 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- cor udolphi 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 anasarea. The muscles most obnoxious to the Entozoon in question are the glutei, psoas, iJiacus 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. Soémmering detected one specimen of the Cysticercus cellulose in the anterior chamber of the eye of a young woman et. 18.* The following is a more re- cent account of a specimen which was deve- eect Oke of the eye of a ent in the w Ophthalmic Infirmary. _ © Case—From the aoa of August, 1839, 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 oplthalmia 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 app!i- cation of a blister hehind the ear, the iuflam- = Bre aos ae p as as quoted by be mann, Mil ise eitra © Naturgescl.icte der witbellosen thiere. rene 119 matory ms subsided, leaving, however, aslight ete 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 mene rege sh se body appeared almost ectly spherical, ex- pers 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 acommon fly. This process Mr. L. observed to be of greater specific gravity than the spherical or cystic portion, so that it always tumed into the most depending position. He also remarked that it was projected or elongated from time to time, and again retracted, so 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. “ Onthe 3d April, when I examined the case, I found the cornea slightly nebulous, the eye free from inflammation and pain, and the a pearances and movements of the animal exactly such as described by Mr. 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. eikle 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. and Mr. Meikle appeared to have deferred employing any means for destroy- ing or removingit ; first, because it seemed to be producing no mischief: and, secondly, be- cause there was a — 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 quina, or some other vegetable 120 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 Tan 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 ihe 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 cellulose 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 Order of Entozoa two species belonging to different genera infest the Hu- man Body. The Swiss and Russians are troubled with the Bothriocephalus latus; the English, Dutch, and Germans with the ‘Tena 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 terebinthine commonly employed in this country for the expulsion of the Tape-worm, From the singular geographical distribution, as it may be termed, of the above Cestoid parasites, the Bothriocephalus latus rarely falls under the observation of the English Entozoo- ENTOZOA. logist. It may be readily distinguished from the T’enia 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 Tenia solium. The head, which was for a long time a deside- ratum in natural history, has at length been dis- covered by Bremser. i is of an elongated form, two-thirds of a line in length, and presents, in- stead of the four round oscula characteristic of the true Tenia, two lateral longitudinal fosse, or bothria, (a a, fig.62, which is a highly-magnified view of the head of the Bothrioce- phalus latus.) The Tenia solium (fig. 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, Fig. 62. Head of Bothrio- and generally hemispherical, lus latus broader than long, and often magnified. as if truncated anteriorly: the ire tont Sy Tenia solium, two-thirds natural size. * Sce Robin, in J_urnal de Médecine, tom. xxv. (1766), p, 222. : 7 ee ee Sy A AER RE PE ENTOZOA. four mouths, or oscula, are situated on the anterior surface, (a, fig. 63,) and surround the central rostellum, which is very short, termi- nated by a minute ae 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 rug, the a 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 (6, 6) are placed near the middle of one of the margins of each joint, and are generally alter- nate. The Tenia 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 Tenia solium, of which one of the margins is single and the other double, as it were two tenia joined by one margin. In the Museum of the College of Surgeons is preserved a fragment of the Tzmia 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 Twnia 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 Ligule. 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, Lwnie inermes; the second those which have a proboscis, but un- armed, Tenia rostellate; the third the Tape-worms with an uncinated proboscis, Lenie ar- mate. 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 Pingucola) somewhat problematical. The Distoma hepaticum fe: 64) is found in the gall-bladder and ducts of the liver of a variety Fig. 64. Dist of quadru , and very com- —o monly in re Sheep. hen it natural size, occurs in the Human species, it is generally developed in the * See Catal. of Nat. Hist. No. 216. 121 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 (6), 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 Tenia, 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 /anceo- 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 Distumata 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, wtat. 20 ; it is represented in situ, at A, fig. 62. Its natural size and shape is shewn at B, the body is depressed,subconvexabove, 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 res disposed in a semi- unar form : a larger sucto- rious cavity occurs on the ventral aspect at the begin- ning of the tail (6 B), anda 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 toa 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 Dr. 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 ( Perca fluviatilis, Linn.) containing numerous specimens of this 122 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 land. 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 Cercarie, which infest the fresh-water Snails; but the have characters peculiar to themselves whic 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-cotylus 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 (a, fig. 81), as in the Distoma. The first or anterior sucker (b, fig. 81) is twice the size of the mouth; and the second (c, fig.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 Celelmintha 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- ENTOZOA. Fig. 67. neath the tunica conjunctiva @ of the eye. It ap 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. Ina 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 acrystalline lens of a man who had undergone the operation of extraction for ca- taract under the hands of the Baron von Grife. In this in- stance the capsule of the lens had been extracted entire, and upon a careful examination half an hour after extraction therewere observed in the fluid above-mentioned two minute and delicate Filarie coiled up 2 — _ inthe form ofaring. One of Filaria Medinensis. thoce worms, who ean microscopically, presented a rupture in the mid- dle of its body, ee 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 papilla, (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 Geiss 4 7 ¢ 4 j ENTOZOA. bronchialis (fig. 68); it was detected by Treut- ere" ler* in the enlarged bronchial glands of a a man: the length of this worm isaboutan inch ; it is slender, subatten- uated anteriorly (a), and emitting the male spiculum from an in- curved obtuse anal ex- tremity (). The next Human Entozoon of the Ne- matoid order belongs to the genus Tricho- cephalus, which, like Filaria, is character- ized by an orbicular b mouth, but differs from it in the capillary form of the anterior part of Filaria bronchialis, the body, and in the magnified. form of the sheath or preputial covering of the male spiculum. The species in question, the ete ispar, Rud. is of small size, and the male (* fig. 69) is rather less than the female. It occurs most commonly in the cecum 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 (b); 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. Fig. 68. With respect to the following ite 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. catheter has been speed 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 args we have examined, and which were preserved in spirit, present a subglobular, or irregularly flattened hae: but when recently 4 bs Pies ay Anat. p. 10, tab, ii. fig. 3— - 123 Fig 69. SS Trichocephalus dispar. (* Natural size. ) expelled, I am assured by my friend Dr. Arthur Farre, that they are perfectly spherical ; they consist of an external smooth, firm, dia- hanous coat, including a compact mass of iow 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 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- tow 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 inzquale 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 which 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 size.) per catheterem ex vesica paupercule educta, ne- quaqaam talia habenda sunt. Corpuscula sunt plus minus globosa, tertiam linez partem diametro superantia, duriuscula, forcipi comprimenti reni- tentia, dissecta solida visa, quominus pro hydatulis haberi possint, quales primo suspicatus sum. Con- crementa sunt lymphatica in vesica mmorbosa ex humotibns alienatis ibidem secretis, simili forsan modo acarenule ex lotio pracipitata.”—Rudolphi, Synops. Entoz. p. 251. * Ibid. p, 252. ENTOZOA. 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 Sterelmintha.* 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- pi 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 (a, fig. 70) truncated, and with one or two papille; the mouth orbicular, the body attenuated at both extremities, but espe- cially anteriorly. The tail in the female thicker, and with a short obtuse apex; that of the male more slender, and emitting a small mesial tubulus (c), probably the sheath of the penis: a dermal aliform production near the same extremity determines the reference of this Entozoon to the genus Spiroptera. There are no specimens of this Entozoon among the substances discharged from the urethra of the female, whose case is above alluded to, which are preserved in the Museum of the College of Surgeons. The following parasite of the urinary appa- ratus, concerning which no obscurity or doubt prevails, is the Strongylus gigas (fig. 71), the giant not only of its genus but of the whole class of cavitary worms. This species is de- velo in the parenchyma of the kidney itself, and occasionally attains the length of three feet, with a diameter of half an inch. A worm of nearly this magnitude, which oc- cupied the entire capsule of the left kidney, of the parenchyma of which it had occasioned the total destruction, is preserved in the collec- tion of the Royal College of Surgeons. The male Sérongylus gigas is less than the female, and is slightly attenuated at both ex- tremities. The head (a) is obtuse, the mouth orbicular, and surrounded by six hemispherical papille (a); the body is slightly impressed with circular striae, and with two longitudinal impressions ; the tail is incurved in the male, and terminated by a dilated pouch orbursa, from the base of which the single intromittent 07 culum (6) projects. In the female the caudal extremity is less attenuated and straighter, with the anus (c) a little below the apex: the vulva (d, fig. 95) is situated at a short distance from the anterior extremity. The Strongylus gigas is not confined to the IIuman Subject, but more frequently infests the kidney of the Dog, Wolf, Otter, Raccoon, Glutton, Horse, and Bull. It is generally of a dark blood-colour, which seems to be owing * These bodies are figured in the excellent ac- count of the present anomalous case by Mr. Law- rence, in the Medico -Chirurgical ‘Transactions, vol. ii. pl. 8, p. 385. ; 4 ENTOZOA. 125 Fig. 71. Fig.72. Strongylus gigas, male. to the nature of its food, which is derived from the vessels of the kidney, as, where suppuration has taken place around it, the worm has been found of a whitish hue. al The Round-worm (Ascaris Lumbricoides, Linn.) (fig. 72) is the first described* and most common of the Human Entozoa, and is that which has been subjected to the most repeated, minute, and successful anatomical examinations. It is found in the intestines of Man, the Hog, and the Ox. In the Human subject the round worms are much more com~- mon in children than in adults, and are ex- tremely rare in aged persons. They are most obnoxious to individuals of the eer eo perament, and such as use gross and indi- gestible food, or who inhabit low and damp * It is the sdpave orpoyyuaos of Hippocrates. localities. They generally occur in the sinall intestines. The body is round, elastic, with a smooth shining surface, of a whitish or yellowish colour ; atte- nuated towards both extremities, but chiefly towards the anterior one (a, fig.72), which commences abruptly by three tubercles which surround the mouth, and charac- terize the genus. The posterior extremity (6) terminates in an ob- tuse point, at the apex of which a prone, econ point may frequently be observed. In the female this extremity is straighter and thicker than in the male, in which it is terminated more acutely, and is abruptly curved towards the ventral side of the body. The anus is situated in both sexes close to the extremity of the tail, in form like a transverse fissure. In the female the body generally presents a con- striction at the junction of the an- terior with the middle third (c) in which the vulva (d) is situated. The body of the Ascaris lumbri- coides is transversely furrowed with numerous very fine stria, and is marked with four longitudinal equi- distant lines extending from the head to the tail. These lines are independent of the exterior enve- lope, which simply covers them ; two are lateral, and are larger than the others, which are dorsal and ventral. The lateral lines com- mence on each side the mouth, but, from their extreme fineness, can with difficulty be Pesceived 5 they slightly enlarge as the ooneitte to about ceetiel of aline in diameter in large speci- mens, and then gradually diminish to the sides of the caudal extremi- ty. They are occasionally of a red colour, and denote the situation of the principal vessels of the body. The oedtaad abdominal longitu- dinal lines (e, fig.72) are less marked than the preceding, and by no means widen in the same roportion at the middle, of the body. They correspond to the two nervous chords, hereafter to be described. The last species of Human En- tozoon which remains to be noticed is the Ascaris vermicularis (fig.73), a small worm, also noticed by Hip- pocrates under the name of : and claiming theattention ofall py sicians since his time, as one o most troublesome parasites of chil- dren, and occasionally of adults ; * in both of whom it infests the larger. intestines, especially the rectum. The size of the Ascaris vermicularis varies 126 according to the sex; the males rarely equal two lines in length; the females attain to five lines (* fig. 73.) They are proportionally slen- der, white, and highly elastic. The Fig.73. head is obtuse, and presents, ac- a2 cording to the repeated observa- tions of the experienced Rudolphi, * the three valvular papille charac- teristic of the genus Ascaris ; but other Helminthologists, who have failed in detecting this organization, refer the species to the genus Oxyuris. Besides the papille the head presents a lateral, semi-obo- vate membrane on each side, the broader end being anterior. The body soon begins to grow smaller, and gradually diminishes to a su- bulate straight extremity in the female. In the male the posterior extremity is thicker, and is spirally inflected and terminates obtusely ; the head is narrower than in the female. In the following tabular arrange- ment of the internal parasites of _ 4! the Human body, theyare disposed en og in the classes to which they appear (* Natural respectively to belong according to sizeof their organization. ENTOZOA HOMINIS. Classis Psycuoprarra, Bory St. Vincent. 1. Acephalocystis endogena, cui locus Hepar, cavum Abdominis, &c. 2. Echinococcus Hominis, Hepar, Lien, Omentum. Classis Potycasrrica, Ehrenberg. 3. Animalcula Echinococci, Hepar, &c. in Echinococco abdita.* Classis ProrerMinTua. 4. Cercaria Seminis, Semen virile. 5. Trichina spiralis, Musculi voluntarii. Classis SrereLMINTHA. 6. Cysticercus cellulose, Musculi, Cere- brum, Oculus. 7. Tenia Solium, Intestina tenuia. 8. Bothriocepalus latus, Intestina tenuia. 9. Polystoma Pinguicola, Ovaria. 10. Distoma hepaticum, Vesica fellea. Classis Cerenmintua. 11. Filaria Medinensis, Contextus cellu- losus. 12. Filaria oculi, Cayum Oculi. 13. Filaria bronchialis, Glandule bron- chiales. 14. Tricocephalus dispar, Coecum, Intes- tina crassa. 15. Spiroptera hominis, Vesica urinaria. 16. Strongylus gigas, Ren. 17. Ascaris lumbricoides, Intestina tenuia. 18. Ascaris vermicularis, Intestinum rec- tum. Anatomy oF THE EnrTozoa. Tegumentary System.—There are few spe- _* These may be considered rather as the Para- sites of the Echinococcus than of the human sub- ject. ENTOZOA. cies of the Sterelmintha in which a distinct external tegumentary covering can be demon- strated. In the Cystic, Cestoid, and most of the Trematode worms, the parenchymatous substance of the body is simply condensed at the surface into a smooth and polished corium of a whitish colour, without any development of pigmental or cuticular layers. The various wrinkles and irregularities, which the super- ficies of these Entozoa frequently presents, result from the action of the contractile tissue of the corium: this substance, in the larger Tania, begins to assume a fibrous disposition, and tears most readily in the longitudinal di- rection ; it can be more distinctly demonstrated as a muscular structure in the larger species of Trematoda. By maceration in warm water the ruge of the integument disappear; the smooth external surface, so well adapted to glide over the irregularities of a mucous mem- brane, is then distinctly demonstrated; and, when magnified, an infinite number of minute pores, variously disposed, are seen perforating the whole surface, especially in the Acantho- cephalous worms. It is these pores which, in the dead worm at least, allow a ready passage to the surrounding fluid into the interstices of the parenchyma, where it sometimes accumu- lates so as to swell out the body to three or four times its previous bulk; and it may be readily supposed, therefore, that the skin here performs some share in the nutrient functions, by absorbing a proportion of the mucous or serous secretions in which the Entozoa are habitually bathed. In the Acanthocephala the skin, which is but little extensible and friable, is united to the subjacent muscular fibres by means of a whitish spongy tissue which adheres to it most strongly opposite the dorsal and ventral longi- tudinal lines or canals. As, however, the skin is with difficulty changed by maceration, while the parts which it surrounds soon go into putrefaction, it can thus be easily se ed and demonstrated as a distinct substance. It presents no definite fibrous structure under the microscope, and tears with equal facility in every direction. In a large Trematode worm, the Distoma clavatum, Rud., which infests the intestines of the Albicore and Bonito, the body is pro- tected by a crisp sub-diaphanous cuticle, re- sembling in its structure and properties that of the Echinorhynchus. A similar covering may be demonstrated very readily in the genus Linguatula, among the Calelmintha, and can be separated, but with more difficulty, from the subjacent mus- cles in the Ascarides. In the great Round- worm (Ascaris lumbricoides) the integu- ment is smooth and unctuous, is more exten- sible in the longitudinal than the transverse directions, tears with an unequal rupture like a thin layer of transparent horn, and preserves its transparency in solutions of corrosive sub- limate, alum, and in alcohol. In this species, in which the digestive canal is completely de- veloped, it is worthy of remark that the mi- croscope does not demonstrate pores in the cuticle, as in the external covering of the pyr FOR Aa ais. ~ 5 5 - in some limit ENTOZOA. Echinorhynchus and other _ sterelminthoid worms ; but a series of extremely minute close- set parallel transverse lines are brought into view, which are anent, and depend on the texture of the epidermoid substance itself. Although a distinct and general epidermic covering cannot be demonstrated in the more simple Sterelmintha, the soft bodies of which entirely dissolve after a few days’ maceration, and which, in animals examined soon after death, are often found in consequence to have lost their natural form, and to have degenerated into a kind of mucus,* yet in most species traces of the epidermic system are manifested parts of the body: thus it ap- in the form of hard transparent homy Rooklets around the oral proboscis in the Cystic genera, as in the Cysticercus cellulose (fig. 61), and most of the Cestoid worms. In the Flori- ceps, Cuv., these recurved spines are arranged along the margins of four retractile tentacles, which thus serve to fix the worm to the slippery membranes among which it seeks its subsistence. In the Trematode worms epider- mic spines are seldom developed ; the species which infests the human subject ( Distoma hepaticum ) presents no trace of them. When they exist in this order, they are either confined to the head, or are at the same time spread over a greater or less proportion of the surface of the body. Of the first disposition we have an example in the Gryporhynchus pusillus, (a tre~ matode worm infesting the intestines of the Tench,) which manifests an affinity to the Tenie armate in its proboscis armed with six- teen strong recurved con arranged in a double circular series. In the Distoma trigo- nocephalum there are two straight spines on each side of the head. In Distoma armatum the lead is entirely surrounded by similar Straight spines. In Distoma ferox the head bears a circle of recurved spines. In Distoma denticulatum the head is surrounded by a series of large straight spines, and there is a series of smaller spines around the neck. In Dis- toma spinulosa the anterior part of the body is beset with reflected spines; and in the Dis- toma perlatum, Nord., the whole surface uf the body is armed with hooklets, arranged in _ Proboscis of Echinorhynchus gigas, magnified. * Rudolphi, Hist. Entoz, i, p. 230, 127 transverse rows, each pes supported on a pone prominence bent backwards, see fig. 91). For a dasvcghios of the complicated horny and cartilaginous parts of the dermo-skeleton, which enter into the mechanism of the suckers of the worms belonging to the genera Diplo- zoon and Octobothrium, we are compelled from want of space to refer the reader to Nordmann’s Mikrographische Beitrage, ( Erstes Heft.) In the Acanthocephala the head, as the name implies, is armed with recurved spines or hooks, which are arranged in quincunx order around a retractile proboscis, (fig. 74); and, in addition to these, some species have smaller and less curved spines dispersed over the neck or body. Among the Celelmintha the genus Lingua- tula is remarkable for the development of four large reflected spines, two on each side the central mouth; and which can be par- tially retracted within depressions of an mei gated semilunar figure. The worm attaches itself so firmly by means of the horny hooks that it will suffer its head to be torn from its body rather than quit its hold when an attem is made to remove it while alive. In the Trichocephalus uncinatus the truncated head presents at its anterior margin a series of hard reflected hooks continued directly from the integument. In the Strongylus armatus, which has sometimes a singular nidus in the me- senteric arteries of the Horse and Ass, the globose head 1s terminated anteriorly by straight spines, but in the Strongylus dentatus with hooklets, Lastly, we may notice the very singular worm found by Rudolpbi in the — of the Water-hen, and which he calls the Strongylus horridus, where the body presents four longitudinal rows of reflected hooklets. The epidermic processes, when thus traced through the different orders of Entozoa, pre- sent but few modifications of form, and have little variety of function; the straight Spines at the mouth serve to irritate and in- crease the secretion of the membrane or cyst with which the worm is in contact; the re- curved hooklets serve as prehensile instru- ments to retain the proboscis and the worm in its position; and when they are spread over the surface of the body, they may have the additional function of aiding in the loco- motion of the species, analogous to the spines which arm the segments of the @strus, which its larva state, like an Entozoon, in the interior of the stomach and intestines of a higher organized animal. Muscular system—Although in every order both of the Parenchymatous and Cavitary worms, living specimens have been observed to exhibit sufficiently conspicuous motions, yet the muscular fibre is not always distinctly eli- minated in them. In the Cysticerci, however, Rudolphi describes two bundles of fibres as arising from the es part of the pody, and expanding upon the w part of the cyst. We dave ipod Sareepccdiog fibres extending to the head in a large Cysticercus tenuicollis; which fibres were doubtless the principal agents 128 in retracting the head within the terminal cyst ; and this part, in the same specimen also, pre- sented a remarkably distinct series of transverse Strie, indicating most probably the circular fibres which contract the cyst in the transverse direction, and protrude the proboscis.* This species of Hydatid, which is common in the abdomen of Sheep, where it is either sus- pended in a cyst to the mesentery or omen- tum, or embedded in the liver, &c. has been the subject of numerous observations, and is generally selected to demonstrate the muscular phenomena in an animal of very simple orga- nization. When extracted from a recently killed sheep, and placed in water at the blood- heat, the cyst may then be observed to become elongated, and agitated with undulatory move- ments ; the retracted part of the body is thrust forth, and again, perhaps, drawn in; during the latter action the anterior part of the cyst becomes wrinkled and is drawn back, gliding into the posterior part of the cyst; the anterior part of the body is at the same time retracted, and is received into the posterior ; and thus by degrees the head and all the body become concealed in the terminal cyst. In the Cestoidea the muscular structure is indicated slightly by impressions on the sur- face of the body, but it is seldom that a distinct layer of muscular fibres can be demonstrated. To the worms of the genus Caryophylleus both Zeder and Rudolphi agree in ascribing longitudinal fibres, which extend along the anterior part of the body and transverse fibres, which are conspicuous in the pos- terior segments. In the Tenie both trans- verse and longitudinal strata of fibrils are stated to exist,t obscure indeed, or almost impercep- tible in the smaller species; but more evident in the larger specimens, in which, according to Rudolphi, each segment has in general its own strata, whence it enjoys, for some time afier being separated from the rest of the body, distinct and peculiar motions; and such joints have been described as distinct species of En- tozoa, under the name of Cucur- bitine. In the Bothriocephalus latus, on the other hand, the lon- gitudinal fibres are continued from one joint to another, whence the segments are less readily separable, and a common and continuous co- vering may be dissected from off the body of this species. Living Twnie placed in warm water exhibit undulatory motions. The body of one of these worms is sometimes found to be tied at some part in a complicated knot, as seen in fig. 75, doubtless by means of these motions. The Tenia solium, when recently expelled from the body by the irritation of a vermifuge remedy, is occasionally ccntracted to the length of a few inches, the Fig. 75. * See Preparation, No. 409 A, Physiological one Mus. Roy. Coll. of Surg. Catalogue, vol. i, p. 115. t Rudolphi, Hist, Entoz. i. p. 223. ENTOZOA. 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 Tenia 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 Tenia 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 Trematoda, 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 Planarie, in which, asin the Tenia, according to our observations, the muscular system is indicated only by striz on the super- ficies of the apparently homogeneous paren- chyma, the me retire of muscularity are stikingly 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 are more vigorous and extensive. Inthe Echinorhynchus the muscular fibres are of a whitish colour, semi- transparent, and of a ge- latinous ita ; they : B), are eminently contractile, ‘potag meet and readily respond to the application of both chemical and physical stimuli. Cloquet ob- served them to contract under the influence of the galvanic current six hours after the cessation Fig. 76. * As quoted by Rudolphi. ¢ Tenia ad trium ulnarum longitudinem ex mulieris ano propen- dens, in casu qnem Wernerus (1, c. 47) refert, tota fere in pristinum hospitium rediit, pars pro- pendens itaque a superiore sursum ducta: similes omnino casus Andryus habet.’—Ibid. p, 223. + Also quoted by Rudolphi, p. 223. ENTOZOA. 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 extemal 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 oes aa on the Ascaris lumbricoides, states that the exterior layers of muscular fibres are transverse, and the inten 5 pag s a large specimen of the S¢ lus gigas, Rud., wines ia hare dissected an pe nar 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 strie 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 and Porocephalus, and the probo- ‘scides of the Cestoid and Acanthocephalous worms. Of the latter organ the Echinorhynchus igas offers a good example. The proboscis in ies (fig. 77) is a short, firm, elastic, ~ bs rical tube, buried with its appropriate mus- in the neck of the animal, as ina heath; and having its anterior extremity (a, b) terminated _* Dictionnaire des Sciences Naturelles, tom. iii. App. p. 40. + Anatomie de l’Ascaride Lombricoide, p. 17, VOL, Il. > 129 Retracted proboscis and its les, Echynorhynch 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, 4 Ss 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 tenioides and the larger species of the Nematoidea, ape? the Strongylus gigas. n the Li a proportionally large ganglion (g, ke. 78) is situated immediately behind the mouth, and below the esophagus, which is turned forward in the figure, at 0; 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 (/, 5 pass backwards and extend along the sides of the abdominal aspect of the body to near the posterior extremity, where K they gradually become expanded and blended with the muscular tissue. In the Strongylus gigas,a slender nervous ring (a, a, fig. 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 distinguishablefrom them 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 4 may be traced round to i, 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- Nervous system and fe- male organs of genera- tion of Linguatula te- scribes the corresponding ventral chord to do in the Ascaris Lumbricoides. On ei . 5A ae pega In the latter species, and most other Nematoidea, a dorsal nervous chord is continued from the esophageal 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: to light, noise, or odour they ENTOZOA, are, as might be ex- pected from the sphere of their ex- istence, totally in- sensible. In those Entozoa which infest the of an animal en 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- curin 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 Gyrodactylus auriculatus, a Cestoid worm, found in the Pranebial 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 onl its occasional and accidental habitation. With respect to the Plunaria these are almost univer- sally provided with eye-specks, varying in num- ber from two, as in the Planaria lactea, (fig. 80, A) to forty, of a brown or black colour, the external covering of which is tran- Fig. 80. sparent and corneous. From the A experiments of M. Duges* on these non-parasitic Stere/mintha, we learn that when the solar light is directed to the head, they escape from itsinfluence bya 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- tomat will be presently noticed. Commencement and termina- tion of the nervous system, Strongylus gigas, magnified. Planaria lactea. * Annales des Sciences Naturelles, 1828, p. 10. + 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, ‘* duo volo corporis albi sanguinea, sepe fulgentia, qualia nullis in Entozois aliis videre licuit, quaque in Gobii minuti Scolece vasa duo rubra parallela pone caput incipientia et retrorsnm ducta, in corpore autem evanida, effingere observavi.” ahd ENTOZOA. : » Digestive organs.—We have already alluded to the two leading modifications of the ali- j ey 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 Calelmintha, 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 hb ok and the alimentary canal itself in terelmintha presents several important differences of structure. Cystica.—The Cystic worms are generally gifted, as in the species ( Cysticercus 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 in which they are lodged. In the larger Conticetes 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 occasioned by the death of the animal in which the hydatid has been tis Cestoidea.—In the Cestoidea the digestive apparatus commences for the most part by two or four oral apertures, to which, in many spe- cies (the Tenia armate), a central uncinated boscis is superadded, as in the Cysticerci. etimes the mouths are in the form of oblong pits or fosse, as in the Bothriocephalus latus, and the allied species grouped under the same gene- ric name; or they have the structure of circular suctorious discs, as in the Tenia solium and _ othertrue Tenie.+ In both genera two alimen- _ tary canals are continued backwards ina straight line near the lateral margins of the body (e, e, * © Osculis canalibusqne dictis uz vim vesica caudali collectam parari potuisse vix credibile, sed hic parati vermem eandem absorbere ideoque semper fere caput huic immissum 3 dari, plurima suadent.”’—Hist. Entoz. i, p. 279 _ t+ Many beantiful preparations, showing the ‘nutrient canals of the Tania solium injected with coloured size and quicksilver, are erved in the finnterian collection, (see Nos. 843, 844, 845.) hese were provers, Lo the life-time of John Hunter, and were presented to that great anato- ‘mist by Sir Anthony Carlisle, by whom they are lescribed in the ‘ Observations upon the Struc- and (Economy of Tenix,;’ in the second yo- ne of the Linnwan Transactions, (1794). » longe aliam vero fiuidi advehendi viam_ 134 Jig. 90), and are united by transverse canals (ff; fig-90) passing across the posterior margins of the segments. These connecting canals are relatively wider in the Tenia solium than in the Bothriocephalus latus, ny Pig apparently depending on the length of the segments, winch is much greater in the forenis ton 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 ig ant 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 Treniz, 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. 2 In some species of Tape-worm, as the Tenia sphenocephalus, 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 Tenia 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, A, 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,t 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 parative ist: 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 Tenia singulos ope absorptionis cutanee perparum, maxime autem ope oscali marginalis nutriri contendit, sed oscnlum hoc vere ad genitalia pertinere in capite inseq > evi Si cl. vir absorptionem cutancam minoris estumat, hac de re non litigabo, sed res alio modo explicari potest. Annon enim ad vasa linearia nutrientia, utrinque longitudinaliter decurrentia, si articuins solutus est, in utroque ejus fine utrinque hiantia, absorbendi officium deferri posset.’’—Synops. Entox, p- 585. s ‘ K 132 tured vessels, the head of the Tai 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.—F our 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 partof 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 cesophagus 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 cecal 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 cecal processes in this En- tozoon are represented (fig. 328, vol.i. p. 654, on that moiety, which is opposite the left han 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 dise and suckers at the postenor extremity of the body. The exterior or ascending oe 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. worm is” ENTOZOA. 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 paradoxrum is ascribed hy Ehren- berg ( Weigmann’s Archiven, 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 coalianty 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, 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 Cercarie; 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. Ina species of Distoma (Distoma clavatum, Rud.) which I recently dissected, Fig. 81. Digestive and nutrient canals, Diplostomum volvens, magnified, ENTOZOA. there is a similar aperture which forms the outlet of a a compressed sac situ- ated between the chyle-receptacles (see Trans- actions of the Zoological pl. 1, 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 Amphistoma coni- cum. The nutritious contents of this canal would seem to exude through the parietes of the cecal 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 brought into com- munication + be 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 cyclosis of the nutrient fluids in the vessels of Polygas- trica, Polypi, and other Acrita, she is probably due Society, plate 4, p.381, Fig. 82. cilia. In a few species of Pla- naria the mouth is terminal and anterior, as in the Distomata ; these form the subgenus Prostoma of Professor Dugts.* In the greater number 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, Jig. 82), varying in length sana to the species, is contained in this cavity, from which it can be pro- truded, and the faoaik 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 ony ges * Dugés, Annales des Sciences, 1828, p. 16. to the action of vibratile- 133 played when a hungry Planaria makes an attack upon a Nais ; 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 s : 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 (b), and upwards to the anterior extremity of the body, distributing its wide ceca on either side; the other two (c, c) descend, almost parallel to one another, and give off their cecal processes chiefly from the outer margin, as in the Distoma. The Planarie 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 ceca, 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 Polygastrica which belong to the Monads: Nordmann observed some brown corpuscles by the sides of the alimen- tary canal of a Diplostomum, 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 diecious generation, they ap- proach very closely the Nematoid Worms, yet paca oh distinguishing character of the Bverelmninthoid class in the structure of the digestive organs. In the Echinorhynchus gigas the mouth is an extremely minute pote, situated on a projectile armed proboscis, the structure of which we have already described. From its posterior are continued two long cylindrical canals (e, e, figs. 83,84) which ad- here closely to the muscular fibres by their outer side, and project on the opposite side into the triangular cavity (h, fig. 84) left between the 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 outlét. 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 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 witha 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 Digestive and gene- a belonging to the organs rative organs, Eehi- of nutrition. Vanalen 9%» In the Calelmintha 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 érachealis, Siebold,) which infests the windpipe of our common Gallinaceous Birds, presents an exception. It was supposed by Montague to be a smgleindividual with to pedunculate mouths; lemnisci, (d, d, fig: 83).- ENTOZOA. Transverse secti of Echinorhynchus gigas. and by Rudolphi was placed m the same group as Distoma furcatum, which 1s 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 toa muscular cesophagus, 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 csophagus, 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 Pentastoma of Rudolphi, the intestine is a simple straight tube, and is surrounded by the convolutions of the oviduct: the two intestinula ceca 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, fig. 71) is surrounded by six papillew ; the esopha- * Synopsis Entoz. p. 564. ENTOZOA. 6, fig. 95) is round and slightly contorted, ne er ilates 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- nuéd of uniform structure, slightly enlarging in diameter to the anus. The chief pecu- liarity of the intestine in this species is that it isa square and nota cylindrical tube, and the mesenteric processes pass from the four longitudinal a 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 é 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 | paraps are more highly de- vel in the ris lumbricoides, in which 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- ‘tally, 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 esophagus (e, fig. Head and mouth of 87) is muscular and four Ascaris 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. 135 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 cesophagus 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 theabdominal cavity. Those a 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. 86), 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- tative 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, Sy and transverse folds, which gradually disappear to- wards the lower part oF the canal. The soft obtuse processes (ff; fig. 86) analogous to those which project from the lining membrane of the abdo- minal cavityin the Strongylus, 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 across the body from one ateral absorbent vessel to the other. In the anterior third of the body these transverse bands (vaisseaur nourriciers, Cloquet,) are quite concealed as b rocesses in question pa a hag oir ( A ices nourriciers, Clo-_ lumbricoides, male. quet), but are very conspicu- 136 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 ieee. 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. : he longitudinal lines (c, ¢, fig. 86, 88), which extend along each side the body of the Ascaris Lumbricoides, and which are very conspicuous Fig. 88. Tg —a 4 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 csophagus: the vessels, on the contrary, become detached from the bands, and pass transversely below the cesophagus to anastomose together, forming a simple a 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- ENTOZOA. unbranched ceca. 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 ceca, 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 cecum 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 cecum is developed from the in- testine at a distance of half an inch from the mouth; and is continued upwards, lying b the side of the beginning of the intestine, wi its blind extremity close to the mouth; from the position where the secretion of this cecum enters the intestine, it may be regarded as re- presenting a rudimental liver.+ 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,t and the circulating fluids in these worms may be- come oxygenated by contact with the vascular mucous membranes of the higher organized animals which they infest. In the Planarie 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 vided with superficial vibratile cilia arranged in longitudinal rows; but these organs of lo- comotion and adjuncts to the respiratory pro- cess are lost when the Distomata resume their sariagd as parasites in the intestines of the a 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 mee of the Zoological Society, Nov. + See the Preparation, No. 429 A, Mus. Coll. Surgeons, Phys. Catalogue, p. 121. ¢ Conf. Echinorhynchus vasculosus,Entoz,Synop. sented the primitive form of simple elongated p. 581. ENTOZOA. by a small orifice in the centre of that part,” and the co ing cavities from which a clear or milky fluid is ejected by the posterior of some smaller species of Distomata and Diplostomata.t+ ans 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. © trace of a generative apparatus has hither- to heen detected in the Cystic Entozoa. They would seem to be gemmiparous, and to have the reproductive power diffused over the whole vst at least in the Acephalocysts, in which young are not developed from any special organ, or limited to any particular part of the cyst a a eae - 4 7 , 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 carer d process or lemniscus, re- —_ by Rudolphi as a male organ. In the thriocephali the ovaries have a similar po- sition, and in the Bothriocephalus latus (fig. 89) assume a stellated figure, with the aperture in the centre, 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 jomts, but the generative orifices are margi- nal and irregularly alternate, and the oviducts may be dis- tinetly seen passing backwards to them : In the Tenia Candelabra- Cc ria a sacciform o exists in each segment, which sends off an oviduct to the marginal svenrooees 9°0000°9 00 fi outlet. Besides which, ac- @ cording to Rudolphi, there is @ a longitudinal canal, uniting Ovorian the different ovaries together, and ova, and undergoing a partial dila- latus. tation at the anterior part of each joint—May not this be the male organ ? The androgynous sores of the generative apparatus is very well displayed in the Ta) worm of this country, the Tonia Solium. 25 Tn each joint of this worm there is a large ed ovarium (i, fig. 90) from which a duct (4) is continued to the lateral open- * See Zool. Trans. pt. iv. vol. i. p. 381. pl. 41. fig. 18. See Nordmann, loc. cit. Ba, t See Nordmann, loc, cit. p. 140. 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 heen regarded, but er ly, as formi part of the nutrient apparatus, 138 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 m Amphis- toma conicum, the ova are impregnated in their eee outward. But in several species of istomata, as D. clavigerum, ovatum, cirrige- rum, and in the Distoma 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 Tenia, is individualized, and its several rts receive a higher degree of development. e have selected the figure which Nordmann has given of the Distoma perlatum, on account Fig. 91. perl 3 hi d. 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 ; wis the oral aperture, b the esophagus Generative organs, Di ENTOZOA.. seen through the transparent integument, cd the windings of the beginning of the simple digestive cavity, ee the two intestinal prolon- gations, ff the dilated claviform ccecal ter- minations of the intestines, g the two internal, and / the two external trunks of the vascular system proceeding to the anterior part of the body; z is the great sacciform uterus, k ap- parently glandular bodies contained therein, 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 pp convo- lutions of the oviduct which are filled with ova, g q the mass of ova which lies above the ovi- duct, and occupies almost the whole cavity of the body, »7 the passages by which the ovaries communicate with the uterus or dilated commencement of the oviduct. The generative organs present some varieties in the Planarie, 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 BSc towards the upper part of the body. he male organ (a, fig. 92) consists, according to the researches of Professor Dugts, 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 (b, 6). 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 (g and /), communicating together by a narrow duct (/), and opening into the terminal generative sac. M. Baer twice witnessed the copulation of ENTOZOA. Planarie iv the species Planaria torva. Upon een, the individuals, he perceived a long ite tube projecting from the genital pore of each, proving the reciprocity of fecundation. Notwithstanding the complicated apparatus above described, the Plunurie are remark- able for their spontaneous fissiparous gene- ration, and the facility with which detached or mutilated parts assume the form and fune- tions of the perfect animal. Fig. 92, 0, repre- sents a Planuria lactea, with the anterior part of the body artificially divided in the longitu- dinal direction ; fig. 92, £, shews the same in- dividual having two perfect heads, the result of the preceding operation. The female generative organs of the Lingua- tula (Pentastoma) tenivides present a strue- ture in some respects analogous to that of the Distoma perlatum: the ovary (n, n, fig. 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 (0, 0, fig. 78). ‘These tubes pro- ceed from the anterior extremity of the ovary, diverge, on each side of the alimentary canal, and unite beneath the origins of the nerves of the body, so.as to surround the esophagus and these nerves as ina loop. The single tube (p) formed by the union of the two oviduets ve 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 (0, 0), communicates at its com- Seeger with two elongated pyriform sacs m, m), which and pour into the ovi- duct an Sakae Aiilhs 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 reci 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 diccious Entozoa generally, much smaller than the female: the generative apparatus consists of two winding seminal tubes or testes, anda single vas deferens, which carries the semen from the testes by a very narrow tube, and afterwards grows wider. It communicates corona with two capillary processes, or penes, which are connected together at their origin by a cordiform glandular body, pa Senting a prostate or vesicula seminalis. e external orifices of the male apparatus, accord- ‘ing to Miratn, 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, Nature Curios. tom. svii. tastoma as having only a single penis, which perforates the jateeeies deewech det Vaso 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 diccious 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 tyvo testes, two vasa defe- rentia, which unite™together to terminate in a single vesicula seminalis, and a long penis gifted with a particular muscular ap; us. The testes (f, h, fig. 93) are cylindrical bodies, pointed at both ex- 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 (k), which together constitute a lobulated vesicula seminalis. This reservoir 1s 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 () 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- I portion (0), occupying the terior extremity of Male A ag the Bods , but which nig chus gigas. pears when the intromittent 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, 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 (A, A, Fig. 93. fiz. 83). They are situated, one at the ventral the other at the dorsal aspects of the body, an 140 are separated in the greater of their extent by a septum: see fig. 84, f,; g, which shows them in transverse section. ey 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 bya 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 Fi/aria, and this appears to be founded on an observation made on the Filaria papillosa, 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. * *« Quelques Matériaux pour servir a |’Histoire des Filaires et Strongles, 8vo. Paris, 1836.’’ ENTOZOA. 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 J’richocephalus 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 y, 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, fe. 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 aleform cuta- neous productions which characterize the Ph saloptere and Spiroptere, is to embrace t 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 esophagus by a slender blind extremity, and winds round ENTOZOA.. the as it descends, gradually enlarging, to Betorerper of the intestine, where it sud- denly contracts and runs down, as a very slender , to near the vulva. It is partly covered by two long slender bodies of a horny sub- stance, re nting a bifureate 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- tative 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: ina 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 o 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 attached to the parietes of the body, and makes a sudden turn back- wards (f, fig. 95); it then forms two long loops about the mid- dle of the body and teturns 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, . 95) is continued, which after forming a 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 ap to have mistaken its blind commencement for its termination, believed that the oviductopened into the rectum. The theory which had suggested itself to Rudolphi of the corre- lation of a simple ovi- duct in the female with the spiculum simplex of the male, and of a double oviduct with Fig. 95. ° aE ipaseiee D2 Jala asia 141 the spiculum duplex, receives additional dis- proof from the circumstance of the uteri and oviducts being double in the Strongylus in- flexus and Strongylus armatus. In teed species (which infests the bronchial tubes and ey vessels of the Porpesse, and which 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 ial 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, pa Be 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 Ascaris Lumbricoides the female organs (fig. 96) consist of a vulva, a vagina, a uterus, which divides into two long tortuous oviducts gradually diminishing to a capil tube, which may be regarded as ovaries. All these are remarkable in the recent animal for their extreme whiteness. The vulva (d, fig. T2;) 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 by a slight constriction. The vagina is a slightly wavy canal five or six lines in length, which passes beneath the in- 142 testine and dilates into the uterus (A, 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 Syn- gamus trachealis, havea cor- responding structure with those of the Nemutoidea. 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 (Hersch and Griiber’s Encyclope- die, th. vi. p. 49, and th. ix. * See Figures of Nematoid Entozoa in copulation, in Bremser, Icones Uelminthum tab. iii. fig. 8. 15. ; and Gurlt, Lehrbuch der Patholog: Ana- tomie der Hans-Saiigethiere, Female organs, Ascaris lumbricoides, tab. vi. fig. 35, ENTOZOA. taf. 3. f.7.) the male maintains an. habitual con- nexion with the female, which has 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 Syngamus 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 eve’ 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. (Sconomy, 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 Acanthocephala, Trematoda, or Ces- toidea ; but it is distinctly discernible in the ova of the Nematoidea; L have also observed and have figured it in the highly organized ovum of the Linguatula tenioides. The ova of the Tenia 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 Bothriocephalus latus ave of the latter form, (, fig 89); those of the Tenia solium are sphe- tical, as are also the ova of Tenia filiformis. 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 Tenia polymorpha. In dissecting a Touraco infested by the Lenia filiform we found that the segments of the Tenia in which the ova were most develo had been ce- tached from the rest of the body, a process remarkably analogous to that which takes place in the Lernee 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 ina 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.+ * Synopsis Entoz. p. 505, pl. iii. fig. 10, 11, + bl Sebold, in Wiatianenn’s Archi. 1835, ENTOZOA. _ The ova of the greater part of the Trematoda _are excluded prior to the full development of the foetus ; 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. Nordmaun 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 5 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 toa 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 Paramecium, 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 whenagain received into the alimentary canal undergo their metamorphosis, lose, like the Lernewe 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 Calelmintha the young cast their in- tegument, and would seem in some species, as the Filaria Medinensis, 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 Linguatula are of an oval form; the aiodone vesicle is situated near the superficies half-way between the two extremi- ties; the vitelline membrane is surrounded with a strong cortical membrane: the develo ment of the feetus takes place out of the aay. In the Strongylus gigas, Strongylus inflexus, and a species of ‘/’richosoma infesting the in- testines of the Goatsucker, we have found the __ fetus completely formed in the ova contained in the uterus or terminal segment of the gene- rative tube, while those in the ovary or narrow 143 commencement of the same part were still oecu- 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 Ascaris Lumbricoides 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 ; i eodem disrupto, quod sepe accidit, ovula vel embryones ex ovariis pro- lapsis parituque ruptis vi quadam et undatim protroduntur.” __ The generation of the Filaria Medineasis is of the viviparous kind, and the progeny is countless,—“ Filarie nostra,” observes Rudol- hi, “ prole quasi farcte sunt, quod si harum ongitudinem illius vero minutiem s y fetuum mu!ta millium millia singulis tribuit.” What is most remarkable is, that these em- bryos are not, as in the Strongylus and the Nematoid genera above-mentioned, envelo in an egg-covering, mor are they included ina special generative tube, but float freely along with a granular substance in the common mus- cular envelope of. the cavity of the body. 144 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 strie, 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. I believe that these muscular bands are the tubes fibrineuses, described by Dr. Le Blond + 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 arent in form; one extremity is obtuse, the y 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 fetus, if it be such, of the Filaria Medinensis. BIBLIOGRAPHY. — Redi, Osservazioni intorno agli animali viventi che si trovano negli animali viventi, Firenze, 1684. Bloch, Abhand. von d. Erzeugung Eingewerdwiirmer. Berl. 1782. Goeze, Versuch einer Naturgeschichte der Eingewerdwiir- mer, und Nachtrag dazn. Leipz. 1782-1800. Val- isneri, Considerazioni ed esperienze intorno alla generazione de vermi ordinarj del corpo umano, Padova, 1782. Werner, Vermium intestinalium, &c. brevis expositio. Leipz. 1782. Retzius, Lec- tiones publice de Vermibus intestinalibus, Holm. 1786. Schrauk, Verzeuhniss der bisherigen hin- langlich. bekannten Eingeweidwiirmer, Miinch, 1788. Rudolphi, Observ. circa vermes intestinales, 2 fasc. Greitsw. 1793-95. Rudolphi, Entozoorum 8. vermium intestinalium historia naturalis, 2 in 3 vol. Amst. 1808-9. Rudolphi, Entozoorum Synop- sis, Berl. 1819. Treutler, Obs. pathol. anat. ad helminthologiam corp. h i. Leipz. 1793. Zeder, Anleitung zur Naturgeschichte des Eingeweidwiir- * Nouvelles Annales du Museum d’Histoire Na- turelle, tom. iii. p. 80, pl. v. + Quelques Matériaux pour servir 4 |’Histoire des Filaires et des Strongles, 8vo. 1836. ERECTILE TISSUE, mer. Bamb. 1803. Olfers, De vegetativis et ani- matis corporibus in corporibus viventibus reperiun- dis comment. Berl. 1816. Fischer, Brevis Entozo- orum s. verm. intest. expositio. Vienne, 1822. Bremser, Ueber lebende Wiurmer in lebenden Mens- chen. Wien, 1819; trad. en frangais, par MM. Grundler et de Blainville, Paris, 1825. Bremser, Icones Helminthorum Systema Rudolphii illus- trantes, Wien. 1823. Jverdens, Entomologie und Helminthologie des Mensch. Koerpers. 2 Bde. Hof, 1801-02. Lidth de Jeude, Recueil des figures des Vers intestinaux, Leid. 1829. , Anatomie des Vers intestinaux, Paris, 1824. Creplin, Observ. de Entozois, Greifesw. 1825-29. Schmalz, De En- tozoorum systemati nervoso, Leipz. 1827. Ejus, Tabule anatomice Entozoorum, Dresd. 1831. Le Blond, Quelques matériaux pour servir a l’histoire des filaires et des strongles, Paris, 1836. Mehlis, Obs. Anat. de distomate hepatico et lanceolato, Gotting. 1825. Nordmann, Mikrographische Bei- trage, 2 Bde. Berlin, 1832. Jacobson, in Nouv. Annales du Museum d’Hist, Nat. tom. 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 Médecine, An xiii. Home, in Philos. Trans. for 1793; Frisch, in Miscell. Berolinensia, tom. iii.; and for further re- ferences to numerous papers on the natural history of particular families and species, vide Reuss's Repertorium, &c. Scientie Naturalis, tom. i. Zoo- logia, &c. Gotting.; the first vol. of Rudolphi’s Entozoorum historia naturalis, and Wiegemann’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 sutficient 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 urethra, clitoris, nymphe, plexus retiformis, the nipples of the mammary glands, less marked in the red borders of the lips, &c.; it also enters into the structure of the papilla 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 papille of the tongue. These consist of the pulpy terminations of nerves enveloped by this tissue; in their unexcited state they appear ERECTILE TISSUE. 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 papillw, 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 iris; 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 urethre, 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 would accord with the syeesrnces Observed by examining sections of this structure after having been © greed and dried, but careful er tion of it when previously prepared by injec- tion, proves the eaecing opinion to be oanded 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- Soo eae alpighi considered it as composed of diver- ticula or appendices*ef 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 __arteriés corresponding, but smaller and less = * On the str and ism of the tongue of the chamelion, by J. H » in Tr ti _ of the Royal Irish Academy, vol. xv. VOL. Il. 145 numerous, formed the 3 spongiosum urethra, 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 urethre 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 Duyerney, Mascagni, Baron Cuvier, Tiede- mann, Ribes, Moreschi, Panizza, Beclard, Weber, &e. and the result has been a con- firmation of the views developed by Vesalius, Malpighi, and Hunter. oreschi, in particular, has shewn that the corpora cavernosa penis, corpus spongiosum urethra, 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 (fig. 97) from Moreschi 146 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 (rami nutritii_), 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- cine. In order to see these vessels, an injection of size and vermilion should be thrown into a separated penis through the arteria 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. Tf 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 some 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 ERECTILE TISSUE. observe the finest twigs of the arteria giving off branchés of this kind which seem much thicker than the twig from which they arose. The annexed figure (fig. 98) (from Miiller’s Archiv.) repre- sents a portion of the arteria profunda penis of man, with its arterie helicine 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 arterize helicine. Their termi- nations may also be com- pared to acrosier. Bya 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 (fig. 99). Fig. 98. wa < After a more forcible in- jection this envelope is no longer visible. hen the arteries form a bundle, the whole is covered by a slight gauze-like membrane. With respect to this in- vesting membrane, Profes- sor Miller appears to con- sider it as performing an important part in ite 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 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 ifs 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 Fig. 99. ‘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. villi of the placenta, observes: our vessels are simple; they bend themselves at the end, but _ donot 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 of the ra cavernosa; they _ oceur but seldom in the middle and anterior : are also present in the corpus ‘ Smisoees urethree, sapeciaily in the bulb; here also they become less frequent anteriorly, and as rset have not been perceived in the glans. ‘They are much more difficult of detection in the corpus spongiosum urethre 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 The greater development of these arteries, adds Professor Miiller, in the posterior parts of the organ corresponds with the fact of erection eo | always earlier evident there, as if the i) 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 ste sometimes to be de- veloped as a morbid production, which has | been described under the names of varicose _ tumour, aneurism by anastomosis, nevus ma- ternus, telangiectasis, &e. Its anatomical cha- _ acters are of the same kind as those of the | | ___[* Iv must be obvious that the discovery of the arteria jevicne by Professor * argon ae this erection, as proving the existence of ves- ooty Role 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- equent enlargement of them, ultimately giving aoe the tortuosity so striking in some cases, is effected by means of a very peculiar set of _ arterial processes superadded to the ordinary nutri- tious arteries of the In the pregnant uterus increased supply of blood is provided for by the enlargemen 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 oe 4 veins which a o large a proportion of the corpora cavernosa. It will be interesting to inquire whether any similar a t of arterial esses in other Acocille cryank— EE. = 147 normal erectile tissue; it varies in size, being more or less circumscribed, sometimes sur- rounded bya 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 gallinacee. The skin of the face, espe- cially that of the lips, is pea 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 iw a vibratory motion amount- ing sometimes to a pulsation resembling that of an aneurismal 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 co fabrica, lib. v. cap. xiv. Venet. 1564. Graaf , De virorum organis, &c. p. 99 et seq. Lugd. Bat. 1668. Malpighi Marcelli opera omnia, tom. ii. p. 221. Londen, 1686. Ruysch Frid., Observatio, C. Amstel. 1691. Haller, Ele- menta, lib. ii. sect. i. § 24, et lib. xxvii. sect. iii. § 10. se Prodromo della grande anatomia, Firenze, 1819. Hunter John, On certain parts of the animal economy, Lond. 1786. Moreschi Alex. Comment. de urethra corporis glandisque structura, Mediolani, 1817. , in comment. Petro- polit. tom. ii. p. 200. Cuvier, Lecons d’anatomie comparée, tom. iv. Paris, 1799—1805. Tiedemann, in Journal complémentaire, tom. iv. g 282. Hebenstreit, G. De turgore vitali in Brera Sylloge, tom. ii. Duwverney, CEuvres anatomiques, tom. ii. Paris, 1761. M i, P. Hist. vesteda rs sect. ii. Senis, 1787, Beclard, Anat. générale, Paris, 1823. Weber, H. E. Allgemeine anatomie, . 415, Braunschweig, 1830. Craigie David, M.D. lements of general and pathological anatomy, Edin. 1828. Mi » in Archiv fur Physiologie, Jahr 1835, p. 202. The paper of Professor Mii/ler has been very ably lated in the London Me- dical Gazette, No. 423. (J. Hart.) . homani EXCRETION.—This term is applied to the formation of those fluids in the animal economy, which are destined to no useful purpose in system, but are intended to be discharged from it, and the retention of which is injurious or L2 , 148 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 uliar, 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, hesides 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. EXCRETION. 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,+ it is always either the result of disease, or of some artificial process, or it is 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 * Thid. p. 249, and p. 1496. + Lecturesin Medical Gazette, vol. viii. t “Jamais je n’ai apercu,”’ says Raspail, “ de cristaux dans le sein d’une cellule vivante et d’ac- croisement,” Raspail, Chimie Organique, § 1378. § Ibid. ¢ 1390, EXCRETION. speculation, but that some such general prin- ciple determines the incompatibility of the nat: 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- _ 8tined 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 4 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 ounces; but this estimate is probably - It seems to be ascertained by the __ experiments of Dr. Edwards, of Despretz, and Collard de Martigny, that there is at times an 1 obvious exhalation of azote by the lungs; and _ Dr. Edwards expresses an opinion that there ; prgeiabiy, at all times, both an exhalation 1 absorption of that gas, but that these _ processes in general nearly compensate one i another. According to Dr. Prout’s views, re- i 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 as the albumen of the blood; and the water _ to be given off chiefly from theweak 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 lungs, with more precision. He supposes the id to be evolved in the course of the circula- tion, 2 my *« process of reduction,” by which “eel gelatin of the animal textures is formed * See Bridgewater Treatise, p, 524, 149 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, robably from the sebaceous glands; the whole oss 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 prime vie 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 su 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. e 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 of the body, besides the liar 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. e quantity of solid matter, animal, earthy, and saline, that off in this way has been stated at about fifteen drachms onanaverage, and is evidently much less liable to change, the density of urine, in the healthy state, always diminishing as its quantity increases, and vice versi. The milk, and the semen, althou destined to no useful office in the system in which they are formed, are rather to be called recrementitious 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, 1s 150 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 ofthe 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 economy, 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- thematous diseases, and especially scarlatina,x— 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. é 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 EXCRETION. 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 ap 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 asa general fact, that the suppression of this evacuation is more frequently followed by injurious effects (particu- larly affections of the nervous system, or viea- rious hemorrhage) than the stopping of an equal amount of hemorrhage, 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, pages 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 res ex- tremely similar ;+} and that this should be the ease 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 étre considerée comme une vesicule organique et vivante, qui est entourée, ou de cavités dans lesquelles abordent des liquides, ou de cellulesremplies elles-mémes de * See Marsh in Dublin Hospital Reports, voi, iii. Two cases of exactly the same description have oc- curred within these few years in the Edinburgh Clinical wards. + Legons d’Anat. Comp. t. v. p. 214. EXCRETION. liquides, Cette vesicule, par sa vitalité propre, absorbe une partie du fluide qui l’entoure; ce fluide est ou de l’eau presque pure, et alors elle en est simplement impregnée et lubrifiée ; ou de l’eau plus ou moins chargée de cette mativre gommeuse, elaborée dans les feuilles, et d’autres matitres alimentaires qui peuvent se trouver portées avec la seve dans les diverses parties. vesicule qui L'a absorbée lui fait subir une action determinée d’aprés sa propre nature, et cette action modifie les matériaux contenus dans la cellule, de maniére A en faire, ou lune des matitres communes que nous avons considérées, ou l'une des matiéres que nous aurons bientdt a examiner, telles que les huiles volatiles, les resines, &c. Certains vaisseaux analogues 4 la nature des cellules jouent le méme roéle sous ce rapport. Les matiéres ainsi localement elaborées peuvent, ou rester dans les cellules ou les vaisseaux qui leur ont donné naissance, ou s’extravaser au dehors et donner lieu, soit 4 des excretions, soit 4 des transports des matitres d’une partie a Vautre 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 Trampentles vaisseaux sanguins, chez les animaux & circulation: ces vesicules sont appliquées sur les parois des vaisseaux; et il est certain que la cavité des vesicules ne communique point immediatement avec la cavité des vais- seaux, puisque le méme fluide n’éxiste point dans leurs cavités. 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 l’on distingue a sa couleur, tandisque les vaisseaux sanguins qui cotoient ces vesicules n'ont que la diaphanieté que leur donne l’etat incolore du sang qui les remplit. Ainsi, les vaisseaux sanguins n’éxistent que comme des moyens d’irrigation pour les vesi- cules qu’ils cotoient, et ce n’est peut-étre que par filtration que le fluide sanguin pénetre, en si modifiant, jusque dans ces vesicules elemen- taires. Le systéme sanguin, consideré dans son entier, forme une cavité sans issue, dans laquelle rien ne peut entrer, et de laquelle rien he peut sortir, autrement que par filtration.”+ y one who is acquainted with the elabo- rate “ yest Lymphaticorum Historia” of Mascagni, will recognize the t 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 derniére analyse,” as consisting simply in * Physiol. Vegetale, p. 215. +L’ t immediat du mouvement vital devoilé, &e. ,. t fi most not be considered as ascertained, that 94 - or tracks of —_ of weed per piper microscope, and usually calle illaries have really, in all animals, and all parts of these, vascular coats, It scems pretty certain, that in 151 the of certain of a compound fiuid through a thin vw yd Eo a4) the exclusion of others; or, according to the for- tunate expression of Dutrochet, as a chemical filtration.“ All that is nec 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 state, and the existence of which will always bean 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 formed from the blood at the ade where they appear, but only separated m 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 already 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 ap 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 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 af Dr. Sen- ter in America, it is stated to have been passed by vomiting, by stool, from the nose and from the mamme, as well as other parts. 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. + London Med, and Phys, Journal, 1828, EXCRETION. 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 lanes are extirpated, this 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-+ But it should not be too hastily concluded, that ail 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. * Prevost et Dumas in Ann, de Chimie, t. xxiii- : + 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 peed connected with the singular fact ascertained by Dr. Prout, that sugar differs from urea simply in containing no azote, and a dou- ble quantity of carbon and oxygen: a discovery which will, probably, acquire a greatly increased importance in the progress of organic chemistry. md | = EXCRETION. Dr. Prout has lately stated strong reasons for thinking, that great part of the contents of the ic vessels are not excrementitious, but 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 fat.* 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 course of the circulation and its abundant changes, as well as to purify it of what has been absorbed "ae 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 prime vie. This may also be probably one principal reason why the great mass of the chyle, and other ucts 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 of nutrition. e know, that in birds, les, and fishes, there is a venous circulation Similar to that of the vena sod through the substance of the kidneys, of most of the blood coming from the lower half of the body; a t of the ingredients of that blood will, there- , 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 phatics.+ 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 intermiz, all the component particles of the blood, both be- _ fore and after its exposure to the air; the most illustration of which power of the heart 1s 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. * Bridgewater Treatise, p. 515, et seq. + Miiller, in Phil. Transactions, 1833. 153 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, and probably 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 fermed. Thus of the contents of the prime vie, 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 through the mesenteric glands, and is, probably, so far intermixed with the blood there, aud 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. Prout} 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 admix- 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, — through the capillaries of the kidneys or iver, 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 ation of the textures and prepared fluids of the body, there is a difficulty in under- standing how these objects can be accomplished J Ti A et QoQ ii is R hy 7 + Bridgewater Treatise, ubi supra. Cuvier, Legons, &e. t. iv. p. 98. j Miiller, whi supra. » &e. 154 in the lowest classes, cularly 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, ioe 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. ( W. P. Alison.) EXTREMITY, (in human anatomy), mem- brum, artus; Gr. eros, xwrov; Fr. extremité, 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- finitioa. When these appendages exist in their omelet 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 * Cuvier, Legons, &c, 27. EXTREMITY. here we find, more or less obviously in differ- ent instances, the same wena a sub- uently aj 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 exce 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. e 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 furcale; 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 / 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. 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 minent; 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 ap ance; it is flattened on its superior and in- ferior surfaces. At its extremity we find an elliptical articular surface adapted toa similar one upon the acromion process; this surface is nearly plane, its long axis is directed horizon- tally from before backwards. fhe body or shaft of the bone ts 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- of the bone at that ; 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, igh which a communication is formed between the axilla and the neck. The posterior boundary 155 of this is formed by the superior border of the scapula, and the internal by the inferior vertebra of the cervical region of the spine, rae the robes constitutes a sort of r, over which e various vessels, nerves, and other Mvhich enter the cavity of the axilla. The anterior third of the first ri beneath the sternal end of the clavicle, fet its two Sees: 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 moe ee 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 ean 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 * Bridgewater Treatise, p. 48. 156 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.* nwomen the clavicle is in general less curved than in men; the diminution in the incurvation ismost 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 vertebra 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.t+ Scapula, scapulum, omoplata, (wos, hume- Tus, Aarts, latus.) Fr. omoplate; Germ. das Schulterblatt—This bone forms the posterior * See Aves, p. 285, vol. i. + Cruveilhier, Anat. Desc. t. i, p. 219. EXTREMITY. 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 coste, 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 posterior], with the vertebral at an angle the apex of which is rounded off; itisslightly concave,and the bone for some way below it is very thin, and the bor- der itselfis 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 S over the ligament. The extent, therefore, of the cervical border is from the posterior superior angle to this notch. The levator anguli sca- pule 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 scapule 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 ee ee EXTREMITY. 197 ' 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.) 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 fibro-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 — is quiescent is outwards . and slightly upwards and forwards. This cavity is connected with the rest of the bone bya 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, (xopaé, 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 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. Tt remains only to examine the surfaces of this bone. The anterior surface forms in the greatest part of its extent a shallow fossa, fossa oy eg which is — above and be- ind 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 scapule become very prominent behind, and are in some degree detached from the ribs like wings, whence the expression scapule alate, 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, ate 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 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 s 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, (axgos, summus, wos, 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. low the spine is the fossa supra-spinata much larger than the preceding, slightly convex, except towards its anterior rt. This fossa is formed by the scapula low and the inferior surface of the —_ above ; it is limited in front by a ridge which proceeds downwards and backwards, from the lenoid cavity to the inferior angle, and bounds hind 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 fosse, thus separated by the spine, com- taunicate through a channel formed on the terior of the neck of the scapula and unded behind by the spine; through this channel pass the arterial and nervous ramifica- tions from the superior to the inferior fossa. The acromion process is evidently continu- 158 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 lownwards 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 seapula, 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, &c. 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 EXTREMITY. 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. the humerus to the scapula. The rule seems to be that where the extremity is — a-pillar of support, the aspect of enoi cavity is nearly vertically downwards. If free- and rapidity of motion be required in addition to as a member of su 5 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 ses the trunk, then the aspect of the glenoid cavity is no longer downwards but outwards, as in man. Structure —The greatest of the scapula is composed of very thin almost papyraceous substance; but its processes, and the en ents at its edges and angles, contain reti tissue. This bone is developed by Developement.—This bone is develo; 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 _ —_ ees and ey oa in the third month as a ete font e 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 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 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 owing to the prominence of two protuberances, one situated anteriorly, called the lesser tuberosity, and the other pos- teriorly, denominated the greater tuberosity. 159 The lesser tuberosity of the humerus (tuber- culum minus) is somewhat conical in 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 subscapularis muscle, and the ridge or spine last described forms the anterior and internal boundary of the pe “Hs groove. e greater tuberosity (tuberculum majus, externum s. posterius) forms a considerable prominence on the upper and outer part of the humerus, being the most external 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 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 ta 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 which 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 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 mpi 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 o this ete is flat and very rit 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. us, 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 brachieus 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 brachieus anticus, supinator longus, extensor carpi radialis longior, and the triceps muscles, e internal edge below the insertion of the coraco-brachialis has the brachizus 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- EXTREMITY. 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 labs transversely, but in transverse extent it falls short of the widest 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 hw! 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 ing from before backwards, takes a curved direction, so that its posterior extremity is much nearer the external rt of the articular cylinder than the anterior. his 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 . a EXTREMITY. portion of the articular cylinder is raised con- siderably above it. This arrangement accounts forthe 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 condyle—more correctly it should be designated epicondyle, 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 Jateral ligament, and to the pronator and flexor muscles of the - forearm. Its ior surface is slightly hol- lowed at the line of its junction with the rest of the bone; the ulnar nerve 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- — it is a massive pillar of support; and we may notice a Nesp 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 pw ; and as this use is found for this bone chiefly in the oan sub- we may presume that in man the angle Scanion e the least removed from a right ile, 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 of the bone which terminate in the epi ea and epicondyle are promi- nent in proportion as the muscles ees het es it are frequently called into play, as n nating and supinatin motions of the fiteivia are shtensive: in the other case this ridge is imperfectly developed, the principal modification of the lower end ‘of the bone is to be seen in the articular cy- linder, where ter depth is given to the trochlea, in order to afford increased strength and security to the elbow-joint. VOL, 11, 164 One of the most singular instances of the developement of bony processes in accordance with muscular power 1s 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 Jarge as the superior ; both the epicondyle and epitrochlea are very highly developed, especially latter, which is accounted for by the Bot 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 nos strength and thickness of the shaft of the ne. 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, ap somewhat quadrilateral in form. Its walls are formed of very dense compact tissue. Developement.—The ossification of the hu- metus 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 sixth year; from the eighth to the ninth year the ossific 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; attwelve 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- joint 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. Ulna (xvBirov, cubitus; Fr. os du coude ; Germ. das Ellenbogenbein.+) 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. tom. i. p. 231. t The term focile was ayplied 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 instrament analogous to our tinder-box, which consisted of two sticks, similar in appear- ance and proportions to the bones of the forearm. ‘ocile majus was the ulna, focile minus the radius, Blumenbach, Beschreibung der Knochen, p, 395, EXTREMITY. 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, (wAeyn, cubitus, xgcvov, 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 Baer 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 erternal 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 b a transverse depression, non-articular, in whic 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- Juce 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- clived 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 brachieus anticus muscle. The superior surface forms the anterior portion of the great EXTREMITY. sigmoid cavity; like the similar surface on the olecranon, it is divided by an obtuse ridge directed from before backwards, into two une- - portions; these portions correspond in pe 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 shaftanatomists commonly lescribe three surfaces. ‘he 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 anconeus 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 hes these the external is at once ‘op its greater prominence; it is s! nearly is two inferice thirds, and superiorly 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 : itis rounded and smooth in its entire extent, and has the deep flexor of the fingers x the pronator quadratus inserted into it. The posterior edge commences at the apex of posterior surface of the olecranon, and ter- mi insensibly towards the inferior fourth the bone. The inferior or carpal extremity of the ulna ea .* ta 163 is very small; it forms a slightly rounded head ; on its posterior and internal is a small process, projecting vertically downwards and ending in a point, to which the internal lateral ligament oft 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 inuer 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. Radius, (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. he superior extremity or head of the radius is a cylindrical head excavated on its superior surface so as to form a superficial cavity, cavitas 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 wy 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 part of which the biceps mus- cle is inserted, the bicipital tuberosity or tubercle of the radius; the anterior of this tubercle, over which the tendon of the biceps glides, is smooth. For about an inch below this the bone retains the cylindrical form, being here embraced by the inferior fibres of the su- eee brevis muscle; but below this the bone mes 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 expa sion, it is concave again. At the superior third of the bone we notice on this _ the nutri- M 164 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 ‘js 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 aie 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 from before backwards; the outer of ese 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 praiecing 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 EXTREMITY. 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 oe, 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 jones 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 aa SS a, a ww EXTREMITY. 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 man: 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- ished at the humeral end, where the latter ne 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 pa 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- » 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 Hann. : a. hook 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 ( ihn os femoris v. cruris, os core. 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 ofa spherical head, connected to the shaft of the bone by a neck. The head is very regu- 165 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. e 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. collum femoris ). 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 inter-trochanteric 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 1s 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 Teoxaw, Toto,) essus exterior femoris ; it is is yriongation vaste 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, with the crista ilii, beyond which it projects exter- 166 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 glutceus 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 fossa 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, 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. Tn the female this angle is somewhat smaller, and approaches more nearly toa 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 night 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. EXTREMITY. 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-posterior 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, linea 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 Fah : 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- neus 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. nile | EXTREMITY. 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 ¢rochlea 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 Fi 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. .—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- = in the shaft, which is bored by a cylin- tical canal. Posteriorly the compact tissue is 167 of great density and hardness, especially where it fos the linen aspera or spine of tba’ ains. 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 Sots gnenl ic reticular texture, in certain 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 hone. Developement.— 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 fetal ex- istence, and is situated between the two con- dyles, occupying the centre of the cartilage. According to Craveilhier 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- Sola in legal medicine ; because from the nowledge of this circumstance alone, namely, that this nucleus exists in the Sip ge re of the inferior extremity of the femur of a fetus, we can pronounce that foetus to have arrived at its full period.” e 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 se’ 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 tact with the articular surfaces of the vertical tibie. 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 owers 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 Kniescheibe). 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 patelle; 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 the patella is very slightly convex, and exhibits a fibrous ap- pearance produced by vertical and parallel EXTREMITY. 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. om 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 as us. 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. ch 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, (cavitates 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. OO SE —<_=— - i ——_— a Se . 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 by a vast number of minute vas- cular foramina, Each condyle projects late- rally beyond the plane of the corresponding of the shat 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 roore, and separates theinternal lateral ligament m 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. oo front ma the head of - tibia there : a 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 patelle is inserted in the latter situation; the smooth rtion 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 uence of the angles being rounded off. Of the three surfaces the anterior is that which ts the greatest dimensions: it is smooth and <6" convex in its entire extent, in- clined wards 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. depth of the superior concave portion is proportionate to the de- vel t of the obi is 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 nded at its extremities and nti aa in os cones At its superior part a triangular surface is marked off from the rest, towards the upper extremity by an oblique line, which from below up- wards, and from within outwards; into this line are inserted the popliteus, soleus, 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 popliteus muscle and forms part of the floor of the popliteal 7 ep Immediately below this oblique line, e 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 terior 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 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- end it gives insertion to the internal lateral igament of the knee-joint and the popliteus muscle, and lower down to the soleus and the common flexor of the toes. The inferior or tarsal extremity 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 ve, which — obliquely downwards and inwards, and odges 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 polka internus. The internal surface of this process is rough and convex; it is quite 170 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 anterior, 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- mulated 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. peroné; 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 EXTREMITY. detect the lines of demarcation between these surfaces. The external 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 peronei 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 peroneus 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 solceus 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 bifureates, 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. he 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. ; of the tendons of the peronwi 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 ; bi to ossify till the fifth year. e tibia constitutes the soe 3.28 pillar of support to the leg. It is f aced perpendicu- ialy 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 su 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. e 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 ponding diverg of the tibia from the perpendicular. When the femur is directed un- usually inwards, the tibia is directed downwards and outwards, 171 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 Srese bones are fully developed and detached: this is icularly manifest in the Phocide and the Felide. 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 ie 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, (Qwxn, Phoca, and pros, 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 inperet 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 congenital 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 Braniocrapuy, see that of Anatomy (Introduction). (R. B. Todd.) EYE, (in human anatomy), oPbaaros, orga- non visus ; us. Fr. Gil; Germ. das Auge ; Ital. Occhio.—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 * Bull. de la Soc. Philomath. t. iii., quoted in Geoff. St. Hilaire’s Anom, de l’Organization, t. ti. p- 211. 172 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 so! yas 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 kick the lenticular form changes the direction of these rays, teaches that a correct image of ex- ternal objects is formed 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. EYE. 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 selwotie 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. vy, Nae EYE. nished with a circle of prominent folds called ciliary , 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 ; dd 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 ina pecu- liar manner, to be presently described as the ciliary ligament; while at the same point it Shaped 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 ofthe aqueous humour, between the cornea and crystalline lens, represent a section of the screen called the iris. f is a section of the crystalline lens. Fig. 102. Through a small aperture in the sclerotic and 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- 173 ed by the cornea being very small, and that behind bounded by the retina being very lange. 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 aqueoushumour. 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 in 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 is 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, robably a sphere of about one inch in diameter. etit, 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 Som- merring, apparently from his own observations, as 10 to 9.5. This belief ina slight differ- ence in dimension may, however, have been 174 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 matter, much difference in this respect might probably be detected in different individuals. 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 codas 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. Sémmer- 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 oxAngow, 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 EYE. the fibrous membranes. The white streaks which give the fibrous appearance appear 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 white 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 merel present a uniform red tint, described as a pin 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 bea 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 in the bottom of the eye than at its anterior part, where it is so thin that itallows 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 ( Spinnwebenhaut, arach- noidea oculi), See the figure of a vertical section of the eye in Arnold tiber das Auge, tab. iii. fig. 2, and copied into Mr. Mackenzie’s work on the Eye.—Ep.] ; 2 ?. ; EYE. situation; but that there is no general thick- ening in this 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 apnaite 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 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 resents a good example of this structure. here 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 rhaps so neatly and perfectly arranged as in irds. 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- Jarged 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 pam in such cases must not, however, be wholly attributed to this dis- tension of an unyielding membrane, | The 175 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, accengeny 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 witha 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, allowing 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 of the spherical sclerotic; it is called cornea m its supposed resemblance to transparent horn, and cornea transparens 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 Sémmerrings, 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. 1 consider it to be a lens and a meniscus. If it be removed from the eye ashort 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, ag 176 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 | eygren be explained. The statements made y 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 = ie 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 bet 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. EYE. 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 ( Aspalaxr zemni.), 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 uliar 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 ee 4 EYE. as speedily recovers its transparency upon the removal of the pressure. The prisai com- ition of the cornea is similar to that of the brous 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. cornea 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, hydrophthalmia, and that peculiar alteration called stuphyloma pellucidum, in which the spherical form of the membrane degenerates into a cone, but retains its transparency. The cornea is destitute of vessels, yet it affords a signal example of colourless and transparent texture sing 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 ermara matter of the same appearance as elsewhere; they are gene- tally said to be between the layers of the comea, but they are evidently distinct cavities circumscribed by the inflammatory process as in other cases; occasionally, however, the whole texture of the cornea becomes infil- trated with purulent are as the cellular membrane in erysi i e rapidity with which this ie na ag destroy. by the ul- Cerative process is another proof of its superior vitality. Ina 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 gonorrheeal 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 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 eerurensiy destitute of that trans cy and regularity of surface so essential for its func- tions; hence the various forms and degrees of VOL. IT. 177 ity enumerated under the technical titles of albugo, leucoma, margarita, nebula, &e. which are probably never remedied, however minute they may be, notwithstanding the 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. hen foreign bodies, such as specks of steel or other metals, are lodged in its structure, the surgeon experiences much dif- ficulty in his — 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 sanpoel ty 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 per on the anatomy of the eye in the Me- vigo-Chirargical Transactions, I endeavoured to direct attention to it without effect., The struc- ture here alluded to isa 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 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 Tefractive 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 che bottom of the ulcer, confining for this appearance, In syphilitic iritis, this mem- brane becomes partially opaque, appearing dusted or speckled over with small dotsaltogether 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 ahorse 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 sclerotic, 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 aj pears, after which the cornea proper may turned off by pulling it gently with the forceps. The use of the elastic cornea does not ap’ to me doubtful. The crystalline lens is lodged ina Speule 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 EYE. stated,continuous with the rest of the conju nctiva, 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 fctus-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 ap ce 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 a 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 toa grape, a term, however, 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, ri 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 at 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. 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 separately 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. he choroid is supplied with blood from the i “espa 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 aon The ramifications are arranged in 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 ae’ ol the middle of the eyeball. ‘hg account is liar arrangement they have received the aha ot vasa vorticosa. They lie external to the ciliary arteries, but the ultimate ramifications tocloy A 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 isplayed as in the arterial injections. e annexed figure is a copy of Zinn’s re- presentation of the vasa vorticosa. This maneuvre’ 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 tapetum. 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 Ruys- 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 ofa 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 in 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. i N 180 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 annulus cellulosus, and by Sémmerring 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, and 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. 1t is evidently a mere band of cellular membrane serving to bind the choroid and sclerotic together at this point, and is obviously a provision essentiaily 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 > sawn 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 EYE. 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 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 RA 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 Sommerring’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. 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 water it 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 rpose for which it is destined. It is found im 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- les 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 n , 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 ior surface of the iris, than pervading the texture of either of these membranes. In old age it evidently fades, and even ap as if absorbed in hes. It is sometimes altogether absent, as in those animals called albinos, where all the usually coloured are unstained. Its use is obviously to t the ot light from beige reflected from surfaces where they should be al » a provision as essential to the ion of the animal eye as to the artificial optical instrament. 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 — in sprees to the exposed of the sclerotic, through which the light a eaeht otherwise pass to the bottom of “— 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 miscroscope “ is 18! seen to consist of very minute flat bodies of a hexagonal form, joined together at their edges. These bodies, which are about yyth 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. rear centre, indeed, of ee 9 hexa- gonal plate is a transparent point, and a Conewhat elevated, the ped trem on the, fosske surface corresponding to depressions to be described in the membrane of Jacob. That part of the membrane of the pigment situated on the pars non 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- Fig. 106. loped, being nothing but the central nuclei separated from each other b: 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 Heine 4 deficient, not only in inferior animals, ut also in man, constituting the variety deno- minated albino, of which the white rabbit affords a good example. The circumstance has attracted considerable attention, and has been the subject of icular observation by Mr. Hunter, Blumenbach, and many others. Dr. Sachs has given a curiously elaborate account of himself and his sister, who are both albinos. The eye in such cases appears of a beauti- fully brilliant red, in consequence of the blood being seen ee 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 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 decom it, and are decom- 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- matic oil, inflammable gases, and carbonate of ammonia. It is, therefore, obviously an ani- mal principle sui generis, its elements being oxygen, hydrogen, carbon, and nitrogen. One hundred in a dry state leave, when incinerated, 4.46 of acalx, consisting of chlo- ride of calcium, carbonate of lime, phosphate 482 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 wvea, 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 at is not exactly in the centre of the disc, ut 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, deseribed 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, varie in flam- mulas quasdam introrsum euntes disposita, quibus aliqua est similitudo rotundorum ar- euum, ad centrum pupille convexorum. Qui- vis flocculus est serpentinarum striarum intror- sum convergentium, et intermistaram macu- larum fuscarum congeries: conjuncti vero floceulenti fasciculi arcum quasi serratum, emi- nentem, ad aliquam a pupilla distantiam effi- ciunt, qui convexus eminet, quasi antrorsum, supra reliquum planum pupilleelatus. Fabrice pulchritudinem nulla icon expressit.” (Ele- menta Physiologie, tom. 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 in 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 part of an inch from its margin, aud from this EYE. point of attachment a number of much smaller strié 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 carnee columne and corde tendinee 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, is, I think, obvious, from the thickness of these cords or strie 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 carnee columne and corde tendinee much magnified. Fig. 107. The posterior surface of the iris is as remark- able as the anterior, but altogether different in its nature. J have given the following des- cription of it in the paper to which I allude in EYE. the Medico-Chirurgical Transactions. order to obtain a correct view of the = 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 my ox to be channels or hollows, as if resulting from a puckering or folding of the membrane. The Pigment is secured from being detached, and iffused in the aqueous humour, by a fine t 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 ee the membrane of the aqueous humour. is delicate membrane may be turned down a 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 thie 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 ae and to afford an appropriate place for it 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 “ In 183 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 pore vessels are disposed, in consequence of the representation of eye; who exhibited rene forming @ series of inosculations at a short distance from the pupil, since called the lesser circle of the iris. y 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 sus 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 sixth. 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 unti! they are finally lost in the iris, as seen in the annexed figure. Fig, 108. From the ‘cing description, it appears that the iris Prom rot distinguished far the tion 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 wa 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 considers it destitiite 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 pupil 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 carnee columne and corde tendinee in the heart. During fcetal life the aperture in the centre is closed by a membrane, hence technically called membrana pupillaris. The discovery of this membrane was first announced by Wachendorf, 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 foetal 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 pupillaris 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 1t is equally erfect; the pupil is however smaller, the iris eing more developed. Subsequently to this date the vesseis 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- mitting 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- Fence takes place, according to my observations, EYE. a short time previous or subsequent to birth: In every instance where I have made the exa- mination, I have found the membrana pupillaris 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 pupillaris of the ninth month. WhereI 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- sed 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 pupillaris 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 ata 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. shews a few shreds of the membrane remaining a week or more afier 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 apa by the rays of light, which, reflected rom 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. e 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 185 in the brain. It is not easy to determine 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 cireu- lar spot, perforated with small holes, from which the medullary material may be ex This is the lamina cribrosa of Albinus, consi- dered to be a part of the sclerotic, but which is teally 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 about 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 during 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- rt and the distribution of its vessels. This is the vascular layer, first accurately described by Albinus. It is a delicate transparent mem- 186 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 fresi 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 netrates the optic nerve at a short distance oin 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 Sommerring, 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 fetus, 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 Philosophica! 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 EYE. 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. For. “ 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 toa 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 ap ce usually presented by the retina ; inatead 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, anda 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 tony the appearance I mention; and, secondly, be- | Pe ple ~ ma me e % ® i EYE. cause I leave the retina uninjured, and present- ing the appearance described by anatomists, jally the yellow spot of Scemmerring, ich 1s 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 [ 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 mustappear 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 passa probe under it, and thus convey the vitreous humour covered by it and the retina from one side of the basin 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 c ter asin 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 ptm 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 candetachitin 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 Cuvier, 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- Totic 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 may be pulled from the membrane, which re- mains attached to the choroid coat, its inner surface not tinged by the black pigment, but 187 resenting a clear white, not unaptly compared y Haller 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 trans tand 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 9 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 ; et the choroid does not recede from the mem- rane 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 mem- brane of such delicacy, is described as being extended between the vitreous humour and choroid, from the optic nerve to the ciliary processes, being merely laid between them, 188 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. Tn 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. 111. 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: EYE. 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. 1 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 dite 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 doing 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 ¢apetum 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 I 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. 112. 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 asmall point destitute of cerebral or medullary fibres, appearing like a hole in the membrane, and hence called the foramen of Sémmerring, 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. Sdm- merring, in the Commentationes Societatis EYE. Regie 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 gee! 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 189 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 centrale. Sur- rounding this foramen centrale the remark- able yellow colour resembling that of gum gutte 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- x wd 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 Sémmerring 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. If the examination be made from with- out, removing the sclerotic and choroid behind, 190 the retina appears to be forced or drawn at this 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- arance of being drawn or folded into the orm 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, IT 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 rt still remaining in water, and bringing the lunt 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 guadrumana, in some of whom it has 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 RYE. firm and opaque. Where the optic nerve enters the interior of the eye-ball, there is a distinet 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 JSoramen 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 the 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. 114. 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 oo = ie EYE. layer only which extends so far, and others that the vascular layer extends over the lens. No one howeyer at present, who describes from observation, denies the termination of the ner- yous 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 poe 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 quowd in the Medico-Chirurgical Transactions 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 defined 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 = 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 ee 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 witn 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- oe remain in water for some days, the a ary the retina begins to give way, and 2 aay altogether detached by agita- tion in water, leaving the vascular layer firmly at the line of termination just de- scribed. With 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 ned 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 191 find those processes covered in several places by a fine semi t 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. R. 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 au 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. e 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, ie ae not completely fill this chamber between the back of the iris and the hollow sphere of the retina, but is discontinued or compressed ata 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 com of water yp recees | certain saline and animal ingredients, deposi in exquisitely delicate and perfectly transparent cellular membrane; hence it is capable of sus- 192 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 ee in strong spirit or weak acid, the mem- rane 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 EYE. 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 adisican! 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 phasors of the choroid, forming part of the undaries 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 blowpi 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 godronné. 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 godronné; 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 ‘odronné. It is formed by the doubling of the yaloid 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. which is very feeble; it thus becomes godronné. Tf the crystalline be removed from its capsule without injuring the membrane which forms this canal, these godronné folds are not formed by inflation or only in a very slight degree, but the canal becomes larger, whe is in man commonly a line and a quarter, a line and a half or two lines in breadth, and not larger in the ox.” An- nexed is a representation of this canal of Petit on a large scale. Pig. 115. As the nature of the connection between the choroid and the hyaloid membrane, the formation of the posterior chamber of the ueous humbur, and the structure of this canal of Petit, have heen the subject of contro- versy, I venture to introduce here an extract on this subjett from the — published by me in the Medico-Chirurgical Transactions. “ If the sclerotic, choroid, iris, and retina be removed one or two days afier death, leaving the vitreous hurhour with the lens embedded on its anterior we observe a number of strie 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 oem does on the choroid, and nar- 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 “compen while others consider these strie 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 rs above stated, commencing behind with a well-defined margin, and terminating anteriorly by attachment to the capsule of the lens, the farsa 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. annexed be dh is a representation of the vitreous humour of the human eye thus treated. * VOL. 11, 193 “Tf the cornea and iris be removed from a human eye within a few hours after death, a dark citcle 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 strie 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 terior chamber of the aqueous humour to Il towards the circumference of the lens, and appear attached there. For myself I can say that having made the dissection in the way just inted out, the eye of course in water, and meath 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 byinflation, and ad- mitting of communication with each other round the lens. It appears to me that the canal of Petit or canal godronné 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 zan pass a small probe all round in this canal, ° 194 taising 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 ens.” M. Ribes, in the Mémoires de la Société Médicale 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 heen 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 yitreous humour with a circle remarkable for its agreeable effect, and which has been com- red to the disc of a radiated flower.” Dr. nox, ina 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 EYE. 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 = 2 mater enters into the coats of the brain. 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 bea 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 lens—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 upil. 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- _ 0.620215 of an inch. ae area OO EYE. ‘sults 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 ecg in question.” The method by which etit arrived at these results must render them of doubtful value, the curvatures having been determined by the application of brass plates eut to the requisite 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 a “ This author has found that the cornea 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 itis somewhat remarkable thatthe 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 5°.” 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 e 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 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 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; thenapplying 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 I then carefully took off 195 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, [ 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 oreight. 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 five to eight gy from fifty to sixty-five years of age. e alteration in power of adaptation, and the indistinctness of vision of pe a 292 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 Sere lens ° 196 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 isa 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 Sommerring. A is the lens of the fetus; B, that of a child of six years of age; and C, that ofan adult. Fig. 117. Aa B Cc The colour of the lens is also different at different periods of life. In the fetus 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 ap 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- RYE. 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 Wintringham, 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 ee tion of twenty-seven to twenty-six. ie 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 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. those 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 ery- Stalline 1.0445, from the vitreous to the crystal- line, using the mean index, 1.0332.” Dr. os 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 — of pa to 13 for its whole size.” ; ing the chemical composition of the lens, Bomelins observes, that tthe 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 a are the same as those of the co- ring 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. tom the preceding observations it might reasonably be sup that the lens is com- of a homogeneous material, such as al- en 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 pr oa stated, consists of certain saline and i —* combined with more than _ their weight of water, and when poicty transparent presents the ce 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 i 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 elit into several portions by fissures extending the centre to the circumference, as seen in fig. 118. This appearance is rendered ill more obvious by immersion in spirit, or the addition of a few drops of acid to the If a lens thus circumstanced be al- remain days in water, it con- unfold itself, and if some expand and eli touched and opened by the point of 197 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. This very remarkable structure of the body of the lens appears to have been first accu- rately described Ly 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 each of these coats or scales was formed of filaments or threads in regular order, side by side, each coat ing 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 [ 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, HN, 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 E LI, return back and become the shortest filaments H N. These filaments H N, passing on the other side 198 of the sphere, 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 K M; 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. EYE. 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. a 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 tle angles furmed by the moon of the ante- rior surface, as in the annexed figure (fig.123). EYE. 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 JAdth of an inch. Upon ap- lying a good microscope to a well-prepared ins, 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 Follows between the teeth of the adjacent one, as in fig. 124. Fig. 124. I have said that the lens consists of an outer ease or capsule totally different from. the solid 199 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, T 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 hysiological and pathological point of view, eserves. That its structure is cartilaginous, I should conclude, first, 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 ve 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 consid , 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 lar and permanent curvature; nor could Bese that if the form of the lens were changed, it could be restored withont 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 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 Joes 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 opegne paper-white ap- rance, and when touched with the needle are und 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 agua 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 Spgeeniy found a fluid to escape. “ Deinde eidem tunici in vitulis etiam, bobusque sive recens, sive non ita recens occisis perforata, pluries animadverti, illico hamorem quendam aqueum prodire: quod et in homine observare visus sum, atque adeo credidi, hujus humoris secretione prohibitd, crystallinum siccum, et epacum fieri feré ut in extracto exsiccatoque crystallino 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 vapaele, 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 ah it may be separated from its capsule when that mem- EYE, brane is opened. These reasons are far from being satisfactory; it does not necessarily follow that parts do not contain vessels, be- cause we cannot inject them; we frequently fail when there 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 oflen 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. Lobé, 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 ca 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 vege 10544 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 ca sule adheres to the ciliary substance, and 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 eh 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 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 ; ne 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 feetus 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 arteriole lentis, in oculo infantis, cujus vasa cera optime erant repleta, summa voluptate mihi vise, quam ere marginem ad convexi- tatem posteriorem dilatam, duobus ramulis perforata capsula in ipsam substantiam lentis profunde se immergentem cortissime con- sot He also quotes the authority of uysch, 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 i Zinn’s representa- Fig. 125. tion of the distribu- tion of the branch of thecentral artery on the back of the capsule, from a preparation in Lieberkiihn’s mu- seum. Similar fi- gures have been iven by Albinus, Ommerring, and Sir Charles Bell. ; the aqueous humour.—In the prelimi eer at the pa tt 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 sis Wigs, = y G a AN (17; y ( S Us 201 uantity of light, and interrupt the passage the ialldion rays. Itis vee anteriorly Aa 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. 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 — chamber is bounded in front by the back of the iris, and behind by the crys- talline lens; with that portion of dhe 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 cireumference of the 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 oe of the hyaloid membrane of the vitreous umour 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 ing 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 a to coneur. Winslow, in the Memoirs of the French Aca- demy for 1721, insists that the iris is in contact with the lens. Lieutaud, in his ern ereet tomiques, is equally itive on this point, and even denies slicgethen the existence, of a rior 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. Saas = tomists a 3 erally, to consider is- tance heaiveias s'lemn ond 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 in contact. In old age the lens be- comes much flattened, and therefore retreats from the pupil, to such a degree that the sha- 202 dow of the iris may often be seen in a crescentic 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 Som- 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 ciili: 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, anda 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- so» influence on the pupil, dilates that aper- ture, «nd, consequently, brings its margin more Opposite the circumference of the lens and at a gieater distance from the prominent central portion. The aqueous heimour, although constituting So essential a part ot” the optical mechanism of the eye, is but small in qwantity ; according to Fig. 126. EYE. Petit not more than four or five grains. Its specific gravity and refractive Dae 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 feetus. 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 ptt 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 pecan 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 » 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. any intervening membrane, it constitutes an unexpected anomaly in the animal regres 2 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 Ay- 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 fig. 127, where the fold of membrane stained with black pigment is seen turned down from that structure. Tn the preceding pages I have availed my- self of whatever valuable and appropriate facts in comparative anatomy I foun culated 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 binds, and the choroid gland or choroid muscle in fishes. Of the pecten—This organ is called pecten Fig 127. Fig. 203 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 ens according to the anatomists of the rench 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. e annex gure, from the work of D. W. Sémmerring, represents it in the eye of the golden eagle. It is composed ofa 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 in 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 fig. 129, from a of Sir E. Home’s in the Philosophi ions for 1822, 129. The first account I find of it is by Petit in the Mém. de l’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- of lel 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 a near its margin. Haller, in his work “ la formation du ccur dans le ulet,” 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 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- hexion 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 Physiologie, t. vy. 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 posterior 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. Sommerring 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 an the great horned ow! 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 tothe 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 Rectéen on Comparative Anatomy, says, « It appears of the same nature-as the choroid, although it has no connexion with it ; it is like- EYE. 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 exce| 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 ¢assowary 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 apts ck 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 a 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. Sémmerring, 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 | vinpavacs to be accounted for perhaps from ir occasional residence in the obscurity of the deep, and at other times near the surface, wepieed’ to the full blaze of sunshine; they Must also be frequently exposed to great pres- Sure at considerable depths. The sclerotic is hot merely a fibrous membrane, but is strength- ened by a cartilaginous cup, and sometimes even by one composed of bone; the cornea is genetally 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 Badu, (cod, haddock, &c.) The external part of the choroid is formed by a most beau- tiful membrane of a brilliant silver aspect, searcely 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 herve, 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 setent 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 amine 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. 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 7 is always deficient. Sometimes, as in the Perca labrax, 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 toacircle. Those who suppose that the eye changes its figure according to the distance of objects, think that this muscle is destined to eer this effect by contracting the choroid ; t 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 theCod 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.’ 3 W. Sommering 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 cmeclad, 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 vascalar 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- >a Transactions for 1796, says that Mr. unter considered the organ in question to be muscular, and proceeds to state that “ this muscle has a tendinous centre round the optic herve, at which part it is attached to the scle- totic 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 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 Viston, Orcan 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 Physiologie. ‘The older anatomical writers were, generally speaking, uninformed on the subject. Rnysch’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 A ti Academii 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 Mémoires de VAcademie 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. Cotemporary 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 Dollenger, Chelius, Huschke, Jacob- son, Kieser, 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 nature 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 academice. Morgagni, Ad- versaria anatomica, Ludg. Bat. 1723, and Epistola, Venetiis, 1750. Haller, Elementa physiologiz corporis humani, tom. v. Lausanne, 1763; also in Opera minora, and Formation du cceur dans le poulet. Zinn, Descriptio anatomica oculi humani, Gotting. 1780, and also in Commentarii Societatis Regie Scientiaram Gottingenses, t. iv. 1754. Petit, in Mémoires de l’Academie Royale des Sciences, 1723, 25, 26, &c. Winslow, Mém. de |l’Acad. EYE. 1721. Moeller, Observationes circa retinam, in Halleri Disputati i select. t. vii. iper, De qi oculi partibus, in Halleri Disp. anat. Lobé, De oculo humano, in same. Wintringham, On animal structure, London, 1740. Le Cat, Traité des Sens, Rouen, 740. Bertrandi, Dissertatio de oculo, in Opere anatomische e cerusiche. Porterfield, On the eye, Edinburgh, 1759. Lieutaud, Essais anatomiq Paris, 1766. Dud- dell, Treatise on the diseases of the horny coat in the eye, Lond. 1729. Descemet, An sola lens crystallina cataracte sedes, Paris, 1758. Demours, Lettre a M. Petit, Paris,1767. Brendel, De fabrica oculi in fcetibus abortivis, Got. 1752. Blwmenbach, De oculis leuceethiopum et iridis motu, Gott. 1786. Wachendorf, C ium litterarium, 1744. Fon- tana, Traité sur le venin de la vipére, Florence, 1781. Walther, J. G. Epistola anat. ad Wilhelm Hunter, Berolin, 1758. Sémmering, Abbildungen des menschlichen Auges, or Icones oculi humani; or translated into French by Demours. So ing, also in Commentarii Soc. Reg. Gotting. Monro, On the brain, the eye, and the ear, Edin. 1797. tti, Observationes dioptrice et anatomice de coloribus, visu et oculo, Patavii, 1798. ig, Lentis crys- talline structura fibrosa, Hale, 1794. Mauchart, De cornea, in Haller’s Disputationes chirurgice, or in Reuss Dissertationes Tubingenses. Dr. Young, in the Philosophical 'Tansactions, 1793 et seq. Home, in several papers in the Philosophical Transactions, see Index. Reil, De structura ner- vorum, Hale, 1796. Rosenthal, De oculi quibus- dam partibus, 1801. Angely, De oculo organisque lachrymalibus, Erlang. 1803 ; or, again, Schreger vergleichenden Anatomie des Auges, Leipzig, 1810. , Systematis lentis crystallina monographia, Tubinge, 1819, and in Radius Scriptores oph- thalmologici minores. Clemens, Tunice cornee et humoris aquei monographia, Gott. 1816, and in ius, S.O.M. Sachs, Historia duorum leu- cethiopum, Solisbaci, 1812. Maunoir, Sur l’or- ganisation de l’iris, Paris, 1812. Ribes, in Mé- moires de la Societé Méd. d’Emulation, an 8iéme, Paris, 1817. Chelius, Ueber die durchsichtige Hornhaut des auges, Carlsruhe, 1818. Voit, Oculi humani anatomia et pathologia, Norimberge, 1810. Hegar, De oculi partibus quibusdam, Gott. 1818. Cuvier, Legons d’anat. comp. Bell's Anatomy. Meckel’s Handbuch d. menschl. anatomie, or the French translation. Sd ing, D.W. De oculorum hominis animaliumque sectione horizontale, Gott. 1818. Knox, Comparative anatomy of the eye, Trans. Royal Society of Edinburgh, 1823. Ci 5 J. Sur la membrane pupillaire, Paris, 1818. Jacobson, Supplementa ad ophthalmiatriam, Havniez, 1821. Dio » Illustratio ichnographica oculi, Werceburg, 1817. Weber, De motu iridis, Lipsiz, 828. Jacob, in Philosophical Transactions, 1819. Martegiani, Nove 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, Jene, 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 usn macule lutre, Vinarie, 1830. Dieterich, F. C. Uber die verwundengen des li ,» Tubing. 1824. Dillenger, Uber das Strahlenblaitchen im menschlichen auges in Acta Ph. Med. Acad. Casar- Leop. Car, nat. cur. t. ix. Horrebow, M. Tractatus de oculo humano, Haynie, 1792. Jacob Imans, Dissertatio inaug. de oculo, Lugd. Bat. 1820. Lieblien, V. Bemerkungen iiber das system der krystalliense bei Siugthieren und, vogeln. Wurz« burg, 1821. Miller, F. Anatomische und physio-~ logische darstellung des menschlichen auges, Wien. 1819. J. Miiller, Zur vergliechenden physiologie des gesichtssines des menschen und der Thiere, Leipsig, 1826. G. R. Treviranus, Beitrage zur anatomic und physiologie der Sinneswerkezcuge des *haned See — FACE. ‘Menschen und der ‘Thiere, 1 Heft. Bremen, 1828, Wardrop’s Morbid anatomy of the eye. Dalrymple’s ~! . 1834. Mackenzie, On de physique, Paris, 1824. Langenbeck, B. C. R. ~ Gott. 1836. Berzelius, Traité de chimie, Paris, 1833. Ammon, Zeitschrift fir die oph- thalmologie. Radius, Scriptores ophihalmologici minores. eils, Archiv, fiir die physiologic. Meckel’s Archiv. F. Arnold, Untersuchungen iiber das auge des menschen, Heidelberg, 1832. Giraldé, Sur |’ ization de l’cil, Paris, 1836. For the Jatest observations on the retina, see Ehrenberg, Beobachtung tiber 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 uoted ; Bidloo, De oculis et visu; the article on the eye in Haller’s Elementa Physiologie; Cam: paretti’s observations ; Home’s popes in the Philo- sophical ‘Transactions; Knox’s Comparative ana- tomy of the eye; Cavier’s Comparative anatomy ; 4. Maller, Vergleichende on des Gesicht- sinnes; and, above all, to D. W. Sommering’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, end, in English, Mr. Dalrymple’s treatise. (Arthur Jacob.) FACE (in anatomy) (Gr. rgocwmoy ; Lat. Sacies, vultus, os; Fr. face; 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 ap Bago 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 Osszous System. Face (in human anatomy). The face is situated before and below ce 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 of the lower jaw and the chin. The disposition of 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 form 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 -partic on the absence of the teeth; but the 207 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 meron st of the characteristics of childhood. Bones or 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 mavxille superioris; 2 ossa palati ; 2 ossa nasi; 2 ossa male; 2 ossa lachrymalia ; 2 ossa turbinata inferiora. The two single bones are, the vomer and the os mazxille in- serioris. The superior mavxillary bones, (ossa maxil- laria 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. 1. a facial or anterior; 2. @ posterior or zygomatic ; 3. an internal or naso- palatine; 4. a superior or orbitar. The borders are three; 1. an anterior or naso-marillary ; 2. a posterior or pterygoid; 3. an inferior or alveolar. The facial surface presents from before backwards, 1. the fussa 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 myrtiform from, 3. the canine (or the 208 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 sutface 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 superioris aleque 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: 1. 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 aud 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 rior half runs, in a direc- tion forwards and outwards, the infra-orbitar FACE, groove, which anteriorly becomes a complete canal (the infra-orbitar canal), and finall divides into an internal or larger canal, whic 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 nee 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 male, 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 Sperone process forms the anterior three- ourths 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- site 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 canalis 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 marillary suture: this border is sur- mounted by a half-furrow which, with that of its fellow bone, forms a ve for the reception of a partof the vomer. The posterior border isshort 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. low groove for lodging the posterior palatine nerves and pe pg The ahs a as the internal surface is placed above the palatine rocess, and is lined on its anterior three-fourths the pituitary membrane. Tracing this sur- face from before backwards we observe, 1. the aperture of the naso-lachrymal canal, situate just behind the inferior turbinated crest the nasal process; 2. posterior to this, the orifice of the mazillary sinus, or antrum of Highmore, which in the separated bone is a large opening, but is contracted in the united face by the lachrymal, the ethmoid, the palate, and pa 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 Jissure 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 of the inferior meatus of the nose; hehind 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 ior palatine canal. The maxillary sinus (sinus maxillaris, antrum Highmori; Germ. die Oberkieferhihle) 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 pape 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-mazillary 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 ure of the nose. At the lower extremity this notch the bone projects, and forms with its fellow of the opposite side the anterior nasal spine. The remainder of this border downwards and a little forwards to terminate on the alveolar border of the bone ik the two middle incisor teeth. my 2. The posterior or pterygo-palatine er, thick, bouied: and vestiont” f united below to the palate bone, and above it forms, with the palate bone, the anterior border of the pterygo-maxillary fissure. 3. inferior or alveolar border is thick and broad, especially behind, and forms about the fourth of an oval. It is rated with conical cavities (alveoli) for the reception of the roots of eight teeth. These cavities are VOL. IL, 209 separated by thin transverse lamin. 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 molaz 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 uadrilateral, and receive the molar teeth. e 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 sapientie, 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 1s 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 Pt £ 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 aleque nasi, the levator labii proprius, the depressor ale 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 terior palatine and dental vessels and neryes. 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 foetal life, near its alveolar border, and it js complete at birth. It presents at P 210 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 su pose that the bone is developed by these ossific ints. 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 intermazillare 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 fcetus 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 palatina; Germ. * See Weber in Froriep’s Notizen, 1820, quoted in Hildebrandt’s Anatomie, B, ii. S, 95. ; FACE. 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 the cireumflexus 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 accessory 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 posterior nasal spine, to which the levator uvulz 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-mazillary 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 maxilla 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 mavillary) 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 sphénoid: below, it becomes broad and is continued along a process which stands WA hs ik pd it hehe ll i ed FACE. 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 pepe) 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. eé outer surface of this process is rough, and is articulated with the upper maxillary bone: its apex is continuous with the external id plate. e inferior border is united to the horizon- tal plate. superior border presents a deep semi- circular notch (sometimes a hole), which with the sphenoid bone above forms the spheno- latine foramen. This notch divides the upper ler into two processes, 1. the posterior a sphenoidal); 2. the anterior (the orbitar). e 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- i y fissure ; 3. an upper, which is con- cave and rests against the body of the sphenoid — 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 se 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 id and the ethmoid ; and with three of 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 fosse. 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 uvule, the lossus, and the palato-pharyngeus. The structure is compact, except at its pte- rygoid process, where it is cancellous. ypement.—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, 211 Malar bones (ossa male y. malaria vy. tygo- 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 or facial; 2. an internal or tem zygomatic; 3. a superior or orbitar. 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 mazillary, rests upon the malar process of the upper maxilla from its extremity to the inferior orbitar foramen. The sterior superior, or temporal border, is waved ike 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 tem , and the zygomatic fosse. It gives attachment to four muscles, viz. the temporal, the masseter, and the two zygomatic; and it gives passage to malar vessels and nerves. P2 ere 212 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 Nasenbeine) 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. is border forms ~ the upper and front part of the anterior opening of the nasal fosse, 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 oe meme longer than ia 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 bya single point about the beginning of the third month. The luchrymal bones (ossa unguis ¥. lachry- FACE. malia ; Germ. die Thrinenbeine) 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 up maxillary bone. The anterior border is slightly grooved for the Svs temps 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 pet odie 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 orhicularis 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 - ‘ i SS EES i i i ie 7 FACE. amg are found at its angles, formed either the ethmoid or from the orbitar plate of the upper maxillary bone. The inferior turbinated bones, ( ossa oe y. turbinata infima; Germ. die untern Muschel- beine ) of an oval form, thin and spongy in their appearance, are placed horizontally along the lower partof 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 fosse 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 es 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 upper border is thin and irregular, and presents from before backwards, 1. a thin edge, which is attached to the pce turbinated crest on the nasal process o upper maxilla; 2. a process (the lachrymal) Which ascends Setwards 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 Rrase (the auricular or maxillary), which, escending 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. vions.— Each inferior turbinated is united with four other bones, viz. the upper maxillary, the lachrymal, the ethmoid, and the okey It is covered with the pituitary mem- ; it contributes to enlarge the surface of the nasal cavity, and to form a part of the nasal canal and middle and lower meatus. __ Its structure is compact. Its development commences at the fifth month by a single point of ossification. The vomer (Germ. das Pflugscharbein ) is of a quadrilateral figure, se resembles a vith meg it is a single and symmetrical , Situated in the median plane, and forming the posterior and inferior 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, 213 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 lamine (sometimes called the ale) 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 ste tt te plate of the ethmoid: below, this border is nearly flat, where it is united to the middle cartilage of the rose. 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 inferius (Germ. das untere Kinnbackenbein, oder der Unterkiefer ). 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 middle or 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 horizonta!, in- clining from before backwards, and a little upwards, and presents (wo surfaces and two borders. The anterior surface is convex, and has in the centre a vertical line (crista mentalis ex- terna), which marks the union of the two halves of which the bone consists in the young subject: this line terminates below in a tri- angular eminence (the mental process). The vertical direction of the lower jaw at the sym- hysis, and its curved figure anteriorly, form- ing what is termed the chin, are both charac- teristic of the human race. From the angles of the mental process arises on each side the external oblique line, faintly marked in front, but becoming distinct as it ascends diagonally 214 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 fossa 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 internal surface of the body of the lower jaw is concave, and presents in the median line, at the symphysis, a vertical crest (crista mentalis 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, yévesov, 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 fossa ) 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 of 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 fossa) 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 fetus 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 FACE. 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 3 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, Seen TOCESSES, 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 dental 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. Fi . The borders of the rami are, an anterior or buccal, grooved below, where it corre- x ae 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- maxillary 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, is turned a little outwards, and in the adult forms nearly a right angle; in the infant and ithe old person it is obtuse. This part. of the bone is prominent and separates the in- sertion of the masseter and internal pterygoid niuscles. On the upper part of each ramus stand two processes, which are separated by the igmoid notch; the anterior is the coronoid, ich is of a triangular form, flattened laterally, and ee front and behind; its summit is somewhat rounded : this process gives at- tachment to the temporal muscles. The cun- 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 at cavity of the temporal bone. The jrection 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 lel to which it runs as far as the second icuspid tooth, where it, divides into two ls, 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, depressor anguli oris, the depressor labii 215 inferioris, the levator menti, the platysma, the genio-hyo-glossus, the pie a ig the mylo-byoideus, and the digastric. Four pairs of ligaments are attached to it, viz. the external and the internal lateral ligaments of the tem- ro-maxillary articulation, the pterygo-maxil- ary (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 fetus 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. e 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 Treru. 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 ocei- pital bone to the anterior nasal spine of the upper 216 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 fosse, of a pyriform 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 FACE. 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 fosse; 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 ges 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 fosse, formed by the pterygoid plates of the sphenoid and by the pyramidal process of the palate bone. External to these are the large zygomatic fosse 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 fosse, the superior dental foramen, its groove 7 ————— FACE. and ; 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 ‘ha sie 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 ag malar bone; superiorly by the inferior surface of the great wing of the sphe- noid below its Set pe ridge; at this part of the fossa are seen the spheno-temporal 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 oak at 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. e 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 u ceksillary bones, externally by The orbitar plate of the sphenoid, and at its outer extremity, which is large, by the malar bone; it forms a communication between the orbit and the 2)80° 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, 217 and establish communications between the cavi_ cabin the face and cranium. e superior or cranial region is irregu- lar, and sgtlehot ee united to Print Arse 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 fosse formed in front of the nasal bones, in the middle by the cribriform bea 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 tl 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 Bx! « parame! 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 fosse; 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, nasal fosse, and the mouth; and with these all the rest are more or less con- nected. These cavities will be described under the several articles, Onnit, Nost, Mourn. Mechanism of the a 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) 218 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- rises. The two upper maxillary bones form y 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 arts 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 fig. 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 foetus is considerable across the orbits, but below these it is narrower in proportion than in the adult. The other chief peculiarities of the foetal face are, the small size of the nasal cavi- ties, the absence of the canine fosse, depend- ing partly on the small vertical diameter of the upper jaw, and partly upon the teeth being still lodged within 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- FACE. 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 fig. 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 ode. 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, (fig. 1333) Fig. 133. \ alveolar bo FACE. and the symphysis inclines from the shrunken car downwards and forwards to the base of the bone, and gives to the chin the jecting appearance which is so character- istic of this period of life. The articulations 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 maxille 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. jose sutures of the face which are, strictly speaking, harmonic, are suchas are not exposed to any considerable pressure; they present, eanértneleen, 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 e 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 “so as those of the nasal and upper maxillary nes. 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 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 219 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 lachrymo-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 fronto-jugal and spheno-jugal sutures; on the zygomatic arch e 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- MAXILLARY 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 OP 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 Annormat ConpitTions or THE CRANIUM); it sometimes happens, not- withstanding, that the bones of the 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 Médecine the case of a Mooris 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. Other cases, but they are much more rare, have been related in which the lower jaw was disproportionately small. When, from either of the circumstances 220 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 se! 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-lip 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 o 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, 1s 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 FACE, 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 aad 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 ied 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. hen 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 rts. Both the upper and lower jaw are sub- ject to osteo-sarcoma, 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 fibro-cartilaginous structure, arge 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 and fungous 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- ————————————EEE ss —<— oe 1 hn ee a 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 egg of which the corrugator supercilii is an associate; 2. the levator palpebre and the occipito-frontalis, which are dilstors, and antagonists of the two The orbicularis palpeb naso-palpebral icularis rarum, ( lpebral, Serot is a fat 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 palpebre, varying in size according to the individual, and giving apparently a ter or less magnitude to the globe itself, which, however, is of nearly uni- form dimensions in different persons. The orbicularis, like the other a muscles, consists of concentric fibres, but it is peculiar in having a fixed tendon on one side, from which a great of the fibres arise; this tendon of the orbicularis, or ligamentum pal- pebre, which is situated horizontally at the inner corner of the eye, is about two anda half lines in length, and half a line in breadth; it ariseg from the anterior border of the lachry- mal ve in the nasal process of the upper maxillary bone, and passing sonenlly 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 atendinous raphé 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 221 called. The other set, which is pale and thin, covers the lids and almost in a hori- zontal direction outwards from the ee 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. lations.—The superficial surface of that part of the muscle which covers the lids (he palpebrales) is connected to the skin by elicate 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. Ihe posterior surface covers, above, the lower _ 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 aleque 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 aleque nasi by cellular tissue, in which runs the facial vem. 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 corragator; 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 involun fibres are those thin ones which cover the lids, are of a pale colour, like the muscles of organic life, and arise from the bral subdivisions of the horizontal tendon. They contract involuntarily while we are awake, in the action of winking, and during sleep in maintaining the lids cial : they also act under the will in closing the lids, particularly the upper. It appears then 222 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 palpebralis) 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- brales are relaxed, It has been supposed, owever, 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. orrugator 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 palpebre 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 vane border and anterior surface of the upper id. Relations.—Its upper surface is in contact, behind, with the frontal branch of the ophthal- mie 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 surfuce 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 aleque nasi; 3. the triangularis nasi; 4. the depressor ale 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- FACE. 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- frontalis 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 aleque nasi.—(l’, ig. 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. Jations.—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 ale nasi. Its inner border above corresponds tothe 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. ~ PACR. Triangularis nusi (transversalis nasi, com- pressor naris, Albin.) (n, fig. 134), is a very thin triangular muscle, ap 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 idalis. 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 aleque 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 ateral 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 yaries 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 ale 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 frenum 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 ay 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- rs of the ale 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 aleque nasi; it covers the myrtiform fossa of the upper jaw: its inner border is separated from its fellow by the frenum. A dilator ale 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, 223 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, he 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. POrbicularis or sphincter oris (labial, Chauss. and Dum.) (0 0, fig. 134) is a thick oval muscle, placed transversely around the aper- ture of the mouth, which varies in size 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 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 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 (l', fig. 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 aleque 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 aleque 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, FACE. 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. Sygomaticus minor (3', fig. 134) is a narrow rounded muscle, often wanting. It arises from the external surface of the os male, 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 yein. Action.—It is an associate of the levaton labii superioris, and contributes to raise the upper lip and draw it a little outwards. Zygomaticus major (3, fig. 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 malz, 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 depressor 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 malw 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 aétion 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 ): (¢ 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 lips, where its fibres mingle with those of the orbi- cularis, the buccinator, and the depressor anguli oris. ee 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- maticus major and the integument. The pos- terior surface of this muscle rests on the upper ——————————— FACE. 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 Sasa fibres taking a direction upwards and forwards, the middle nearly ver- tical, and the anterior describing a curve u 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 a ee with the t matic and levator anguli oris. ~ lstionse= Sea 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 (quadratus menti ), (d, fig. 136, 137) flat 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. VOL. It. 225 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 (houppe 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. This muscle . 136, 137). 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 Buccinator (6, muscle attached to it. The buccinator is a broad flat muscle, and arises, 1. behind and in the middle from an aponeurotic line, the terygo-maxillary ligament or inter-maxillary igament, which is common to it and the su- perior constrictor of the pharynx, and which is Q 226 extended between the lower extremity of the internal pterygoid plate of the sphenoid bone and the posterior extremity of the internal ob- lique line of the 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 gh eye 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 the 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. lations.—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 the 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 thern 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 orationg f 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 itionbans 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 cheeks, and its fibres become separated and curved. If now the muscle acts, the fibres become straightened, and the fluid is expelled feom 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 FACE. 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 aboye. 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 triaugularis oris, the base of the lower jaw, the facial vessels, and part of the masseter. The arrangement of its facial portion is all that need be described here. 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 —— See SS ee ee hh a -. ~*~ oe. - eS eee FACE. 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 ag gland towards the angle of the mouth. tis the risorius Santorini, which is, however, often wanting. The platysma draws down 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 iw 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 lialf of the buccinator muscle : anterior to this it becomes lost in the surrounding cellular tissue. General review of the 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; 6, the depressor labii inferioris and pla- which draw down the lower lip; c, buceinator, 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 palpebre and pal- is, with the associate, the corrugator supercilii; 2, the dilators, the occipato frontalis and levator palpebre. About the nose there are, 1, a constrictor, the depressor ale nasi; 2. the dilators, levator labii superioris aleque 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 palpebre, the naso- ialis, and the dilator ale nasi, are sixteen = in number; if we add the occipito- talis, the corrugator supercilii, and the nineteen pairs, and one symmetrical, orbicularis oris. Of these, four pairs : =» herby oder pairs to the nose, ten and one single one to the mouth: two 227 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 Puysrocnomy. It will be sufficient to observe here that the muscles which express lively feeling and the gay passions, such as the occipito-frontalis, the levator 8 pebrarum, the levators and dilators of the lips and their commissure, do for the most 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 or draw them from the median line. 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. The 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 aby is even beautiful, tinting the cheek and ips, as in the act of blushing, assisting in the ——- of the feelings and ions. 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 —_ 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 the 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 Carormp 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 Q2 228 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 sod pterygo-maxillary fosse ; 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 submazillary 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 of the fuce 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: 8. 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, pecs the masseter, the masseteric nerves. e portio dura, after turn- ing over the posterior border of the lower jaw, forms a rs (the pes anserinus) within the otis gland, and divides into a great num- er 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- FACE. 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 Firru parr or NERVES, Sevenrn parr or CrerespraLt Nerves, and Puysi0GNomy. Abnormal conditions of the soft parts of the Juce.—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 bloodvessels 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 ave not unfrequently 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 nevus 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 nevus, 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 ale 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 fuce 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 doulouroux, 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 ae j 7 FASCIA. 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 inful affection, for the divided nerves spee- ily 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 cellulur 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. metimes 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- cy’ 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, &c. which frequently make great ravages not only in the soft of the face, but even in the Laden! 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 _. of the face are subject to congenital mal- ation. 1. Its apertures may be closed more or less firmly ; this happens with the eye- lids, nostrils, and lips. 2. There may be de- 229 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 BrBLrocRapHy of this article, ,see ANATOMY (INTRODUCTION). (R. Partridge.) FASCIA, (in general anatomy,) ( Binde, sehinge Scheide, Flechsenhaute, Germ.) This term is applied to certain membranous expan- sions, existing in various regions of the body, and forming coverings to icular 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 fascie 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 fascie—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 laces 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 uliar almost to each region of the body; it is gene- rally known under the name of the superficial Juscia. 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 to which 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 ee membraniform expansion, and the principal variety it pre- po different su line as regards the reater 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 connee- tion with the proper cellular covering of sub- jacent organs, whether muscles or tendons. 230 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 fascie of opposite sides are intimately united so as to form a dense line, called by some anatomists linea alba cervicalis; thence on each side the fascia divides into lamine, 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 Necx,) we learu 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. In 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 Aspomen. * Anatomical Investigations, Philadelph. 1824. + On the thymus gland. FASCIA. 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. £: 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 suffers 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 abdominal 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 fascia, 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. Chirurg. t. i, p. 42. a a es a — = DA a a a ee ee eat FAT. name fascia is interna. It is in ork at poeeead amrbeoees of the prin- ¢ipal 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 the 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 fuscia 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 pepe of the sac itself. fi rr 2. Aponeuroses or aponeurotic fascia—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 J erm they assume a yellow colour, and exhibit most manifestly the y of elasticity. e greatest number of the fibrous aponeu- roses are connected with muscular fibres, and in fact serve as tendons to them, and are de- seribed 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 neuroses, they are com of the yellow astic fibrous tissue. I have also seen the fascia lata thus converted. A second class of these aponeuroses consists of those which cover the soft f parts in particular regions. In general we find that where there are many muscles covered, the aponeurosis sends - — by which each Hoan is separately inv , these processes being ulti- mately inserted into the panieeas 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 satliote nt 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 m its tension by a muscle, called from that 231 office, tensor vagma femoris, 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 fascie 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 lamella 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 fascie 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 op their progress to the surface, a property which is likewise observable in the cellular fascie, 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 fascie 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, Godman, Anatomical Investigations, Phila- delph. 1824; Velpeau, Anat. Chirargicale, t. i. ed. 2de; Puillard, Description complete des Membranes fibreuses, Par. 1827; Cruveilhier, Anat. Descript. t. ii. Aponeurologie, Par. 1834; Bourgery, Anatomie de l’homme, t. ii. (R. B. Todd.) FAT. (corsage, wsusdrn, adeps, Low, toa ; Fr. graisse ; Gers: Fett; Ital. grasso.) Under this term we include a variety of animal 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 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 asource of nutriment of which the ani- mal economy may avail itself on emergency ; and accordingly in cases of emaciation or atro- phy, itis 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 Apvrpose Tissue.) The general chemical characters of fat have been long known, as well as its important pro- rty of saponification by means of the alkalis ; ut the real nature of the changes which it un- dergoes in this process, and the essential dis- tinetive 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,t that we have taken the following details. All the varieties of fat are resolvable into mixtures of stearin and elain, (from oreae, suet, and sAasov, 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 * Recherches arom 7 sur les corps gras d’ori- gine animale. Paris, 1823. ao der Chemie, B.3and 4, Dresden, FAT. 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 hog’s-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 e/ain, 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. When 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 margarie and oleic acid, which when fused concrete at 150°; and 9. of glycerine. According to Chevreul’s analysis, the ultimate elements of hog’s-lard are— Carbon, ....+.+++ 79.098 Hydrogen,....... 11.146 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 by pressure between folds of filterin paper at 77°, is colourless, fusible at 122°, an 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 boiling 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 :— << ~~ ee TO le eaten ne FAT. PAT. ELAIN. Carbon........ 79.000 78.566 Hydrogen...... 11.416 = 11.447 Oxygen ...... 9.584 9.987 100.000 100.000 3. The fat 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 burnslike wax. 100 parts of alcohol dissolve 15 of this stearin: when saponified, it yields 0.95 of fat acids, which fuse at 130°. The eain 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. Goat'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 pk 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 decom 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 hydrate of baryta, evaporated to dryness, and decomposed by distillation with sulphuric acid diluted with its weight of water: the acid is — 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 aren difficultly soluble in water. ery lutton fat is ga than that of beef, acquires a peculiar odour by exposure to air; when melted it begins to po about 100°. It requires 44 parts of boiling alcohol for solution, Its stearin, when fused, begins 233 to congeal at 100°, and its temperature rises on solidification to 113°. 100 of alcohol dissolve 16 of it. Its elain is colourless, slightly odorous, sp. gr. 0.913, and 80 parts of itare soluble in 100 of boiling alcohol. When saponified, it yields a very small quantity of hircie acid. This species of fat, together with - 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 9.556 100.000 100.000 100.000 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 muriatie acids render the latter combination turbid, nitric acid tinges it dark brown with effervescence; and it is coa- gulated 3! 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 phocenic acid, also glycerine, and oleic and margaric, 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 phocenic 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 s ceti; 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 concretes on cooling; by the aid of heat, it * Physeter macrocephalus, or Cachalot. 234 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 yery 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 margarate and oleate of tassa, and a peculiar fatty matter, which ‘hevreul calls ethal,* and which amounts to about 40 per cent. 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 barytic 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 ses over in vapour when distilled with water. t burns like wax, 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 when 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. Berard. Ure. Carbon.... 76.1 79.0 Hydrogen.. 12.4 10.5 Oxygen... 11.5 10.5 100.0 100.0 SPERMACETI. CETINE. Berard. Chevreul. Carbon.... 79.5 81.660 Hydrogen.. 11.6 12.862 Oxygen .... 8.9 5.478 100.0 100.000 * From the first syllables of the words ether and Icohol, in uence of a blance in ultimate composition to those liquids. FAT. EruAL. (Chevreul: ) Atoms. ts. Theory. Experiment. Carbon., 17 102 79.69 79.766 Hydrogen 18 18 14.06 13.945 Oxygen.. 1 8 6.25 6.289 1 128 100.00 100.000 9. Phocenine is a peculiar fatty substance contained in the oil of certain species of por- fone (Delphinus phocena and _globiceps). ‘hen 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 hircie 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 when cooled down 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 pa alcohol. The neutral salts of this acid (phocenates ) 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 phocenates 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 “f 7.69 825 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 water, or 91 + 9 = 100. 10. The fat of birds has been but little exa- mined; Chevreul states that the fat of geese concretes after fusion at about 80° into a gra- nular mass of the consistency of butter. Ac- cording to Braconnot 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 110°, and soluble in rather more than three parts of anhydrous alcohol. When saponified, it yields margarie and oleic acid and glycerine. * The same acid is contained, according to Chevreul, in the ripe berries of the Vi . —_—=—_ = FEMORAL ARTERY. The fat of the duck and the turkey nearly resembles the above. 11. Among insects, peculiar kinds of fat have been obtained from ants, and from the cochineal insect. The latter has been examined Py Pelletier and Caventou. (Ann, de Ch. et hys. viii. 271.) It is obtained by digesting bruised cochineal in ether, evaporating and re- dissolving the residue in alcohol, till it remains upon evaporation in the form of colourless pearly scales, insipid and inodorous, and fusible at 104°, 12. Under the term adipocere, we have else- where described a species of fatty matter which pp to result from the slow decomposition fibrine ; and in some diseased states of the body, a large proportion of the flesh occasion- ally puts on the appearance of fat. In the former case, it has been supposed that the pro- duct is the fat originally existing in the body, which, during the putrefaction of the other parts, has become acidified, that is, converted into margaric, stearic, and oleic acids; and that these acids are more or less saturated by the ammonia which is at the same time gene- rated, and by small quantities of lime and magnesia resulting from the decomposition of certain salts of those earths pre-existing in the animal matter. This view of the nature of adi- pocere appears so far correct ; but the quantit: of the altered fatty matter which was found 4 the cases alluded to, and in others where heaps of refuse flesh have been exposed to humid pu- trefaction, is sometimes such as to render it highly probable that a portion of the fatty matter is an actual product of the decay, and not merely an educt or residue. In regard to the apparent morbid conver- sion of muscle into Rt in the living body, Berzelius observes that, because the muscles become white, it has been assumed that they are ee ee into fat, — o the pearance depends solely upon the absence or red blood,” for the souacied under such circumstances do not lose their power of mo- tion. The truth is that, in these cases, the accumulation of fat goes on to such an extent in the interstitial cellular membrane of the muscular fibre, as gradually to occasion its almost entire absorption, and such of the mus- cles as undergo this change gradually lose their coed Swe Two mutton-chops, which have undergone this change, and in which the altered muscle and the ordinary ex- ternal layer of adipose membrane are quite dis- tinct, are preserved in the Museum of the College of Surgeons, and there is a printed pamphlet giving an account of the symptoms under which the sheep laboured. What may be the chemical peculiarities of the fat depo- sited among the Albtes, as compared with the ordinary fat, has not been ascertained. The above is an enumeration of such of the varieties of animal fat as have been chemically examined. In their general characters they closely resemble the corresponding compounds of the vegetable kingdom ; and, with the excep- tions specified, the process of saponification effects upon them very similar changes: they 235 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 produe- tion of carburetted hydrogen for the purposes of gas illumination, a variety of binary com- pounds of hydrogen and carbon, with some other ucts, 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 icular 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 magnus 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. . % io Anatomy of the Arteries, vol. ii, p- L 236 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 correction, 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 * Boyer, Cloquet, Harrison. FEMORAL ARTERY. 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, quam proximé, 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 fascize: hence the student, not having a fixed point of reference, is often ata 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,+ 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 sitnation 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 toa 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 wiil 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. + This point will be discussed again. ee An sb eee 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 a’ lation femoral sheath will be applied. It s also related to the crural nerve or its branches, and it is contained, together with the vein, in acanal of fascia, which will be denominated the femoral canal. It is necessary to dwell here, for a little, upon the distinction between the two appel- lations femoral canal and femoral sheath, that aconfusion 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 Leeacog 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 Jemoral sheath will be applied. A distinction between the two structures is ne 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 a ied not to the canal as formed by the ja 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 fascie 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 th ut 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. 237 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 ee 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 lastl to the vastus internus muscles; the latter of which is inte 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 = 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 soou compensated by another in the opposite direction. In its lower half the artery 1s 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 b dividing the two superior thirds of the thigh into three equal parts, and they will occupy each, according to the stature, from three to ~ inches. Ss acai he superior stage reaches from Poupart’s ligament to the pone at which the as is first covered by the sartorius: during this, its upper third, the vessel is not covered b muscle, except at its termination, where it is overlap’ by the inner margin of the sartorius: it is therefore comparatively super- 238 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 cellular stratum, the anterior wall of the femoral canal, and the peorageion of the fascia transversalis or the moral 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 fascie 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 yein, the superficial femoral veins, and those veins and arteries by which the inguinal glands are supplied. The saphena vein ascends, from the inner and FEMORAL ARTERY. 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 somewhat 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 more likely to prove a source of embarrass- ment in operation. They are smaller than the bi eet 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 the form one or two considerable vessels, whic’ ascend external to the saphena, and open into the femoral vein in 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 third, 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 in exposing the femoral artery at this part of its course, and ieee 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 Poupart’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, “=r Ui eit 4 = —————— I i ii FEMORAL ARTERY. which is called its eribriform portion, and over the course of the femoral artery, across which they are placed obliquely: they are separated from the vessel by the superficial lamina of the iliac portion of the fascia, and by the prolongation of the fascia transversalis, with the interposed cellular structure; and they derive numerous arterial and venous branches from the main trunks beneath : 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, through the a a 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 escapes, and thus they become the means of establishing that connection be- tween the fascia in the groin and the subeu- 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 the 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, but 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 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 eannot, by any precaution of the surgeon, be protected certainly from injury. 2dly, That phagedenie 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, i which it is attached from without inward, divides at that point into two lamine, a deep 239 one and a superficial one; the former passes inward and akon from the ligament, upon the s 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 ilio- pectineal eminence it also meets and is iden- tified with the pubic portion of the fascia lata, which is attached to the tineal 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 decaihed from it, it appears as an oblique partition dividing the crural arch into two parts, an external containing the iliacus and 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 Gimbernat, 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 lamine, 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 and 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 ae 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 fasciw, 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 pew: of the fascia lata. The two fascie 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 pubie portion of the fascia lata situate behind them. As it descends upon the vessels, FEMORAL ARTERY, the prolongation from the transversalis 1s umted 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 fascie 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 width 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. or adipose stratum is in between them. The last particular in the disposition of the prolongation of the fascia transversalis, having ce 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, gtd one between the artery and vein, upon e inside of the former; the other internal to the latter, between it and the femoral ring: by those the abdominal aperture of the femoral 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 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 closely 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 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 innominatam, external to the iliopec- tineal eminence, having the two structures, already mentioned, interposed.* Below 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, wh is not internal to the eminence, and upon the lamina of the iliac ion of the fascia lata covering the muscle, which at its most internal Part is inserted into the eminence; consequently the pop liegeer ge ~ the —- must i ternal to point me, observation wi be found to confirm this view. VOL, II. 241 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 se ed from them by a Space of some i 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 nerveabove, 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 Jeyel; the ries however, is somewhat anterior to it, probably * Harrison. 242 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. Tn 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 lamine 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 eserving 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 lamine 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 FEMORAL ARTERY. thickness of the fascia, and give to it the ap- pearance of a tendinous 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 upon 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- a J 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 pas 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 part 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 theartery 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 des Regions, t. ii, p. 485. ed, 1. & ' ’ s FEMORAL ARTERY. At the termination of its third stage the artery 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- in of the united tendons of the adductor ost and the adductor magnus above, by the connection between the tendon of the adductor magnus and that of the vastus internus 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 nts a variation from itsaccustomed dis- ition,so much so that it may almost be held to 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 py 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. @ pulsation of the aneurism, which was arrested on the appli- cation of the ligature, returned after an interval of some ee and became nearly as distinct as before: it ceased again upon the third day, but the patient was carried off on the sixth day aga erysipelatous inflammation of the thigh. examination after death, it was ascertained that the disposition, which has been described, was p t, and that but one of the two vessels had 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 Portalt+ states that the crural artery has been seen to divide into two large branches shortly * Green on the Varieties in the Arterial S: > and Sandifort, 0) » Anat. Pathol. iv, 97. + Anatomie e, t. iii, p. 326. 243 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 pepemen! division of the femoral artery into two trunks of equal size, running parallel and so near together, that they might be convenientl included in one ligature, is recorded by Gooch in the Philosophical Transactions for the year 1775, it being the third instance in amputations of the thigh, in which he had observed such a lusus nature in the arterial system ; but it is not mentioned whether they were instances of the first or of the second kind of variety: he himself, whether from examination or from in- ference, appears to have concluded that both trunks were prolonged into the lower part of the limb. Those deviations have been accounted repe- titions of similar irregularities in the brachial artery, than which, however, they are far less frequent. It is a matter to be regretted that neither in the case of Bell, nor in that of Houston, has any account been given of the disposition of the artery of the upper extremi- ties or of the other thigh, Branches. of the femoral artery. —The branches given off by the femoral artery are numerous; but the trunk of the vessel bein itself intended for the supply of the leg an foot, the branches which it gives to the thigh are, with the exception of one intended speci ally for the nutrition of that part, inconsider- able in size. The artery gives branches to the integuments of the abdomen, to the glands and other structures in the groin, to the external organs of generation, to the muscles in the vicinity of which it passes, to the inner side of the knee; and, lastly, it gives the large branch, adverted to, for the supply of the thigh, and by which those inosculations with other arteries are formed, by means of which chiefly an in- terruption in the course of the main vessel is compensated. Those which have received names are five, viz. 1. the superficial epigas- tric ; 2. the superficial or external pudic ; 3. the superficial anterior iliac; 4. the profunda; and 5. the superficial superior lease aasiodar arteries. Of those the first four arise from the artery within its first stage ; the epigastric, iliac, and pudic being given off immediately or at a very short distance below Poupart’s ligament; and the profunda at a greater although a variable distance from that part. 1. The superficial epigastric artery (artére sous-cutanée abdsuiinale Cloquet; inguinale, Chaussier;) ordinarily arises from the front of the femoral, immediately below Poupart’s liga- ment. Sometimes it is given off from a branch common to it and either one or both the ex- ternal pudics; or it may proceed from the pro- fndat It first comes forward through the fascia lata, and then ascends over Poupart’s * Ibid. p. 239. t Boyer, ay 244 ligament upon the inferior part of the abdomen, superficial to the aponeurosis of the external oblique muscle, and enclosed in the subcuta- neous cellular stratum. Its course is irregular, at times nearly parallel* to that of the deep epigastric within the abdominal wall ; at others ascending directly upon the abdomen; in ge- neral it pursues the latter course. It is consi- derably smaller than the deep epigastric artery, and is concerned altogether in the supply of superficial parts, and in establishing commu- nications with other vessels. Its first branches are distributed to the inguinal glands and co- verings: during its ascent upon the abdomen it gives to either side branches which supply the superficial structures, and inosculate through the ventral foramina with branches of the inter- nal epigastric from within; and it terminates by communicating with the same and with those of the internal mammary, and of the inferior intercostals. It is, unless in case of disease, a small vessel, and of consequence only from being exposed to be divided in cer- tain operations, viz. that for inguinal hernia, or that for tying the external iliac artery. 2. The superficial or external pudie arteries (scrotales ou vulvaires, Chauss.) are generally two, distinguished into superficial+ and deep, or superior t and inferior: of those distinc- tions the latter seems preferable, inasmuch as they are both equally superficial in their dis- tribution, and the difference between them in this particular amounts to no more than that the second continues longer beneath the fascia lata than the first. They arise in general either directly from the femoral, or from a trunk com- mon to them with the superficial epigastric, with which they are of nearly equal size. The superior is given off immediately below Poupart’s ligament; comes through the fascia lata, and at the same time gives branches to the inguinal glands; runs, superficial to the fascia, inward and also upward toward the pubes; and either divides into two, one of which as- cends above, the other, the more considerable, continues below that part; or, as it proceeds, it gives off small branches which ascend above the pubis, and supply the superficial struc- tures upon the inferior middle part of the ab- domina! wall; while it is itself continued to the scrotum and side of the penis, the coverings of which it supplies; or into the labium in the female. Its branches communicate with those, which the external organs of generation receive also from the internal pudic artery, and with branches of the epigastric arteries. This branch is usually divided in the operations for either inguinal or femoral hernia. The inferior external pudic artery arises from the femoral at a greater distance from Poupart’s ligament than the former: at times it is given off by the profunda§ artery, or from the in- ternal cireumflex,|| or from the superior branch :{ at others it is absent.** It is situate beneath the “ Harrison. t Cloquet. t Harrison. Boyer, Cloquet, Tiedemann, Harrison. Tbid. ** Ibid, FEMORAL ARTERY. fascia lata through a greater extent of its course than the superior; runs inward across the pec- tinalis muscle, covered by the fascia; passes then through the fascia, and gains the scrotum or the labium and the perineum, in which it is distributed, communicating with the inferior branch of the former and with the perineal artery. Its course is at times so far from Pou- part’s ligament that it crosses behind the sa- phena vein. Occasionally a third* external pudie arte is present, arising either from the femoral itself, the profunda, or the internal circumflex artery. 3. The superficial anterior iliac artery (ar- teria circumflexa ilii superficialis, Harrison; external cutaneous, Scarpa; artére musculaire superficielle, Cloquet;) arises from the outer side of the femoral artery, or at times from the profunda:+ it runs outward in front of the crural nerve, and after a short course divides into three branches. Its first comes from within the fascia lata and is distributed to the superfi- cial inguinal glands: its second branch also comes through the fascia, runs round the ante- rior and outer side of the thigh, below the spinous process of the ilium, and is distri- buted superficially: and its third runs outward and upward, beneath the fascia lata, toward the superior anterior spinous process of the ilium; supplies the sartorius and tensor vagine muscles at their origin, and also gives branches to the iliacus internus. This artery communi- cates with branches of the gluteal, the deep anterior iliac, and the external circumflex arteries. 4. The profunda artery (arteria profunda JSemoris ; intermusculuire, Chauss.) is the vessel by which the muscles and other structures of the thigh are for the greater part supplied, whence it may be regarded as in strictness the femoral artery, the trunk of the femoral, in its general acceptation, being distributed to the leg and foot: it is also the channel through which the communications between the femoral artery and the main arteries of the trunk on the one hand, and of the lower part of the limb on the other, are established, and by which, in case of interruption of the first vessel, either below or above the origin of the profunda, the circulation is to be restored: it is therefore an artery of great importance, and also of great size, being nearly equal to, though for the most part somewhat smaller than, the femoral itself, while in many cases it is fully equal to it. Hence, probably, it has received the name profunda Jemoris, deep femoral artery; and by many the femoral artery is distinguished into the common Jemoral and the superficial and deep femorals ; the first extending from the entrance of the vessel into the thigh to the origin of the pro- funda; the second being the vessel from the point last mentioned to that at which it becomes popliteal ; and the third the artery which is at present under consideration. ' The profunda artery for the most part arises from the posterior and outer side of the femoral * Scarpa, Boyer. + Cloquet, Scarpa, eS ae SS Se -”6 SUC FEMORAL ARTERY. ata distance, yarying from one to two inches, below Poupart’s ligament: it descends thence backward into the inguinal region, posterior to the femoral artery, and corresponding to the muscles situate behind them in the same order as the femoral itself until it reaches the adductor longus: it then passes behind that muscle and continues its descent between it and the adductor magnus, until after it has given off its last perforating branch, when it also perforates the magnus at the lower part of the middle third of the thigh, and finally is distributed to the short head of the biceps and the vastus externus, gives to the femur its in- ferior nutritious artery, and anastomoses with the descending branches of the external cir- cumflex artery, and with branches of the pop- liteal. During its descent the profunda recedes from the surface more than the femoral artery, So that it lies nearer to the bottom of the in- guinal space, and when placed directly behind it, is separated from that vessel by an interval, which is occupied by the femoral, the pro- pote og the circumflex veins. It is women pani a corresponding single vein of con- fiderable size, the pesfiaae no. which in the upper part of the thigh is situate before the artery, intervening, as has been mentioned, between it and the femoral artery. It is con- tained at first within the same sheath with the 3 but it is presently received into a sheath, an offset from the back of that which encloses the other vessel. It has not an immediate relation to any nerve. Such are the general relations of the pro- funda ; but it presents frequent varieties, which derive importance from the practical connections of the femoral vessels. e@ par- ticulars, in which it is subject to diversity, are the precise situation and relation of its point of origin, and the relation of its course to that of the femoral ¥ The profunda arises generally, as has been Stated, from the posterior and outer side of the femoral; but at times its origin is directly behind that vessel, at others directly from its outer side, and occasionally again from its inner side, as may be seen from fig. 3, tab. xxxili. of Tiedemann. The situation of its origin also is variable, at times being close to Poupart’s ligament, at others at some distance from it. According to Boyer* it corresponds to “the middle of the space comprised be- tween the pubis and the little trochanter; sometimes higher, but rarely lower.” Accord- ing to Scarpa,t the division of the femoral artery takes place “ at the distance of one inch, or one and a half, very rarely two inches, below the crural arch in a well-formed adult, of the ordinary stature.” According to Har- rison,} the —— arises “ in general about two inches below Poupart’s ligament, some- times an inch or two lower down, and some- times much nearer to this ligament.” Of those * Traité complet d’Anatomie, tom. iii. p- 150. Searing on Aneurism, Wisha’ % rt’s translation, ¢ Op. cit. vol. ii. ps 144, 245 three accounts that of Scarpa appeats pre- ferable: the “ distance between the pubis and the lesser trochanter” is variable, and affords no guide for the living subject, and the author has never witnessed the origin of the vessel by any means so far from Poupart’s ligament as the statement of Harrison would imply: a distance of four inches, which may be un- derstood from it sometimes to occur, would bring the origin down to the point at which the sartorius generally commences to overlap the femoral artery, and this is manifestly alto- ther too low; while on the other hand ean states expressly that it is never below the maximum point which he has laid down, viz. two inches from the ligament, and Hodg- sont asserts that “ it very rarely arises so low as two inches.” The maximum distance im- plied in the description of Harrison is that which has been laid down by Bell as the me- dium point of origin, on which Burns re- marks, “ I infer that Mr. Bell has described this artery from dried preparations, in which, from the retraction of Poupart’s ligament, the origin of the profunda seems to take place lower than on the recent subject.” The only objection which can be made to the view of , is that the vessel not unfrequently arises nearer to the ligament than one inch from it, its origin being at times abso- lutely at it, and having been in some few instances observed even above the ligament, before the femoral had escaped from the ab- domen, or more properly from the external iliac artery: of this extraordinarily high origin four instances have been potbidied: by Burns,§ and Tiedemann || has met with it ina female, upon both sides. Tiedemann§ has also in- ferred from his researches that the profunda arises nearer than usual to Poupart’s ligament more frequently in females and in subjects of small stature than in others. The relation of the course of the profunda to that of the femoral is the next point of variety. The main course of the former is external to that of the latter; in arriving at its destination, however, it does not at all times pursue an uniform course, but presents diversities in this respect, 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, pega on Diseases of Arteries and Veins, iS Diseases of the Heart, &c. p. 319, 20, id Pp- id. oe Tabularum Arteriarum, p. 323, d. 246 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 Tiedemann+ 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,t 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- tities 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- | of the two vessels will almost certainly be found to be the profunda, for if that artery haye 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 ehade 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 Anatomice. + Tabnle Arteriarum. Tab. xxxi. and fig. 2. tab. xxxiii. + Reflexions et Observations Anatomico-chirur- gicales sur l’Aneurisme, tab, lére. Op. cit. i Harrison, op. cit. vol. ii. p. 165, Hargrave, System of Operative Surgery. FEMORAL ARTERY. caution recommended of alternately compres- sing the vessels and ascertaining the 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 es, and not being remarkable either for their size or their communications, have not received part- 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 circumfler 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. 1. 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, yiz. 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 glutceus medius mus- cles, and concealed by the tensor vagina 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 gluteal, and also with the deep cir- cumflex ilii arteries. The anastomosis with the glutcal 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, pl. 1. Og aS a FEMORAL ARTERY. at times 80 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 crureus, and one or two to the vastus externus: they are accompanied, several of them, by branches of the crural nerve, and they run for a con- siderable distance, particularty 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 aré by no means uniform in number or destination, more or fewer of the arteries just described being at times branches of the profunda itself; eis, at times that to the vastus internus, that to the crureus, 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 vagine muscles, and superficial to the crureus. It gives, in this situation, branches to the crureus, 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 of its course it traverses the upper extremity of the vastus externus, and ves off, 1. branches upward and downward into the muscle; 2. a branch or branches which tun between the vastus and the bone, and supply the periosteum; 3. a branch to the luteus maximus at its insertion, which, after ishing it branches, perforates the muscle aud 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 $a which crosses between the femoral and profunda arteries, superficial to the latter, yield to join the femoral or the profunda Mm. 2. The internal circumflex artery is a larger vessel than the external 7 is feted off by the ged usually after the external, and arises from the inner side of the artery, but at times it arises before the external. “ According to - det it “ very Sequels proceeds from the smoral artery, prior to the origin of the pro- funda;” it has been found by Burns* cinibg 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 * Op. cit. p. 319, 247 the lymphatic sheath ;” and in the second “ it trave! the front of the common sheath of the great vein and also of the lymphatics ;” and in either case, as observed by Burns, it as be exposed to t danger in operation for fétlionll Heute. ET cording to Gheen,* 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 space 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 bi Tiedemann superficial circumflex branch, whic! 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. e 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- it gives the articular artery of the hip a branch, small, but remarkable for its course and * Op. cit. p, 31. 248 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 glutcei 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* Cor 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. FEMORAL ARTERY. divides into two or three large branches, of which one ascends and is distributed to the gluteus maximus, communicating with the gluteeal, 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 rans 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 nerye, and, during its passage from the front to the back of the thigh, to the pectinalis and the ad- ductors. According to Harrison, “ this artery is sometimes a branch of the internal circum- flex; its course is nearly ale to that vessel, and is separated from it by the tendon of the pectineus muscle, the first perforating artery passing below that tendon, 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 vagine, 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, it pursues a similar course and is distributed similarly to the last. The perforating branches - of the profunda are subject to much variety 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. 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 crureus muscles: it has been elsewhere stated that the descendin branches of the external circumflex, destine to the last-named muscles, and one of those to the vastus externus, at times also arise from the profunda itself. spe panies given off the see perforating a: , the profunda, very muc reduced os nai itheoc its deiceae behind the adductor longus muscle, inclining at the same time outward, and external to the femoral artery: it passes through the adductor magnus alittle above the passage of the femoral into the ham, giving it small branches; then tra- yerses 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. is is usually called the anastomolica magna artery, but there being no more reason to apply the epithet anastomotic to it than to the other branches 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 ils 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. - 249 integuments and other superficial structurés of the articulation on its anterior part, and com- municates freely with the other articular arte- Ties. 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-membranosusand semi- tendinosus, and also to the sartorius: when it has reached the inner side of the knee, it divides into two, of which one 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, turning 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 interval 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. e 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, ponents 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 represented 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, iliacus, 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 1n 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 afier the interruption of the femoral artery, has been so long established that it is 250 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, gluteal, 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 blood 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, No. 1, Jan. 1836, from the experience of Sir Astley Cooper. Through the gluteal 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. FEMORAL ARTERY. By the communfeations, 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 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 oe distributed to the periosteum. pon 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 * Réflexions sur l’Aneurisme, tab. ii. ae —— eS {eee eS ee FEMORAL ARTERY. 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, i ent 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- Tuption, 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 trank 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 ma continue unaltered; thus in Sir A. Cooper’s ease* 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 easet 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 tothe 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 femoral itself: 4. that the femoral artery and its branches thenceforward are to be con- sd "s ital Reports, t recone el Be vol, xx. sidered branches of the iliac arteries, rather of the internal than of the external, the trank 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 rofunda 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 down » 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 Jess 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 “yeasts 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 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 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 branches 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 profunda, as in the operation of 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 deahenta: 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 Sidaeens: 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- _ of Medical and Chirurgical Knowledge, vol, i. 259 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 Medico-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, resents 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 to those. The propriety of thus distinguishing them will appear in a strong light, when those 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. FEMORAL ARTERY. 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 ape 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 his 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 hay- 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 aitery’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 EE ay yes i ee ih il Dal FEMORAL ARTERY. the latter be lost. It will be recollected that in the two inferior stages the artery is covered by the sartorius and by two lamine 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 se of thelimb. 2. The deep layer of fascia, y 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 shear Re te 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, ding to the i 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. P 253 + outer margin of the sartorius. Those objec- tions are avoided by cutting upon the outer edge of the muscle, inst 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 carry 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 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 cansed 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 cireum- 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 neces: 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 supe- rior internal articular artery with the femoral must be also avoided.* is mistake, which has occurred, ought not however to occur again in 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 doubt the vessel which presents, must, if the arti- cular, conduct us directly to the trunk itself, * See that vessel, 254 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 —* 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 42 puration in the vicinity of the track of the FEMORAL ARTERY. 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. arch downward, and when he comes to the place where he does not feel any more, or v 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 moral artery. A little more than three inches above the a 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 in 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 p' ings to be adopted in the operation of taking oF the artery in the “pps 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 ak ea facility is between four and five inches below Poupart’s ligament, and which is Scarpa’s point,t the displacement of the sartorius is accounted a pet 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 EL aawing 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, fae seeking, to the second and not to the first third of the vessel’s course, within the Jatter of which it must be performed in order *H » &e. + The distance at which the sartorius crosses the artery varies according to the stature. 255 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. e 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 ina 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 tule 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 daal teaead 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 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 inyestment, which immediately encloses the two vessels and connects them to each other, and which has been elsewhere denominated the. afemoral sheath ; this, though thin, is dense, and is to be expected to offer resistance to the 256 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 gent!y 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 Srey 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 manceuvre 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 Pore 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 FEMORAL ARTERY. 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 o 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. the latter, it does not promise more successful results: should lary 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 su 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 longation of the fascia transversalis, Sphich ema 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 eperation, 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, 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 inted out will enable = b dageen : decide see profunda ar 3 an ifficulty will, ‘aioe 2 gear aed Getter Bo 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. cial inguinal vessels of | 257 first stage of its course at Jeast, 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 eases 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 ba aged 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 ARTERY. ( B. Alcock.) FIBRINE, (Fr. fibrine ; Germ. Faserstoff.) Under this name physiologists and chemists have generally described the animal proximate principle constituting that part of muscular Jibre 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 re 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 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 fibrine ; 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 precitiinied from its aqueous solu- tion by that acid in the form of white flakes, which appear to be a supersulpbate. 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. Muriatie acid gelatinises fibrine and then gradually dissolves it, forming a dark blue liquid, or purple and violet, if retaining any hematosin. 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. When 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, Wéh- ler’s German translation. Dresden, 183]. See reg ersiig 35 Transactions, vol. iii. p- FIBRINE. 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 andl ae 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 hematosin. 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 b 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. ates nises nor dissolves in acetic acid: ammonia acts as pote but less energetically. _ When fibrine is digested in solution of ees 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 ollowing 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..0004 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. Vhecvcccsss 19.72 e060 Ges cece ee SOc reese 0050.70 ° 5.6 eee 7.04 oe eee edG. oe eee 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- - When Berzelius first obtained fat from fibrine digesting it in alcohol and in ether, he con- uded that it arose from the decomposition of @ 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 ved rete the es is — whence appears it existed saponified, or "80, in the blood. Se _ Another important variety of fibrine is that which ‘constitutes muscular fibre, but it is so \ with the nerves and vessels and cellular and adi membrane, that its pro- ‘perties are ly always more or less modi- * Handbuch der Theoretischen Chemie. 7 phur, the presence of which has been above’ adverted to. fied by foreign matters. The colour of muscles eyes 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 alsé modified by the con- tinued action of hoiling 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 eva ration ; this residue, treated with alcohol of the specific gravity of .830, communicates to it (1 a portion of a peculiar extractive matter, ani the insoluble remainder (2) is white, soluble in water and crystallisable, and has been called by Braconnot /eucine.+ 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. + Ann. de Chim, et Phys. xiii. 119. 82 260 haling the odour of roasted meat, and partl sublimes: it is difficultly soluble in alcohol. Itdissolves in nitric acid, and yields on eva- poration a white crystalline compound, the nitro-leucic 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. Tt 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 alcohel but soluble in water. (W. T. Brande.) FIBRO-CARTILAGE, (Cartilago liga- mentosa v. fibrosa ; Fr. Tissu fibrocartilagineus ; Germ. Faser-Knorpel oder Band-Knorpel ).— As early as the time of Galen we find certain organs distinguished by the appellation vevgo- Kovdewdes cvvdecyosr, 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 ligamentose and cartilagines mixte. 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 ander 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 powerof 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- eartilage 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.”+ 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, Lipsie, 1747, t Hunter on the Teeth. FIBRO-CARTILAGE. 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 Arricutation. I may here, however, notice the statement of Weber* in regard to the dises interposed between the vertebre, 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 whic it becomes reduced to a fibrous expansion (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 lamelle 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 1s no doubt owing to the intermixture of fibrous tissue; cartilaginous laminz, 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 bundles, 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 vertebre are completely destroyed, the intervertebral dises will remain quite uninjured. * Einige Beobachtungen iiber das Structur der Knorpel und Faser-Knorpel, in Meckel’s Archiv for 1827. } : j : (’ i FIBRO-CARTILAGE. Fibro-cartil dry readily when exposed tothe air and yom 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 su ce. Their chemical com 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 dise, those fine and uniform cylindrical fibres with wave-like bendings described and figured by Jordan ;* 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.t 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 ented 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 acticle 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.{ Miiller and Miescher have further investigated the subject and confirmed the statements of Purkinje.§ Tn examining thin slices of cartilage under “ Uber das Gewebe der Tunica Dartos, &c. Miiller’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 pavped in a subsequent part of this article, but in adults it is composed of adipose tissue! a stry Diss. inaug. Vratisl. 1834. Shalit s § Vid. Miiller, Vergleichende Anatomie der Myxinoiden, Berlin, » and Miescher, de ossium fsa’ Structura, et vita. Diss. inaug. Berol 261 the microscope by transmitted light, Purkinj observed fa i little bodies irregularly dis. peed through its texture, of a round or oval orm, 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 pata Korperchen ). n some cases, as in tem- porary cartilage, they ap- to consist of mi- nute ules; they pre- sen this appearance likewise in the cartilagi- nous of the cranium of a 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 ale 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.+ Fig. 139. * Sic Miescher, + The cartilages most liable to ossify by the pro- ss of age in man, are those which most quently exhibit, after a certain period, a per- manently ossified condition in some of the inferior classes of animals, Thus, in birds, and among Is, in heiroptera, and cet q 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 To the second class of cartilages belong those of the external ear, of the epiglottis, and the capitula of Santorini, 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 lamine, as those between the pubes, pieces of the sacrum and coccyx, and, ina 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 thaps the sclerotic coat of the eye in some Fshes! 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 henomena 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 CartizaGe.) 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 rare, but in the hog tribe two bones extend from the intermaxillary bone into the cartilage of the proboscis, — Vide Miescher, loc. cit. p. 27. FIBRO-CARTILAGE. 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 dises, which is commonly spoken of under the name of ulceration, is frequently coin- cident with caries of the vertebre, 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 oc7ur- 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.t 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 interpubie 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 accidentall developed ; we find them in or connected vial the uterus, in tumours, and in serous or sy- novial membranes. (R. B. Todd.) * Brodie on the Joints, edit. 2d, p. 231. + Pathol. Anat, by South, — FIBROUS TISSUE. FIBROUS TISSUE,* tela fibrosa, vel ten- dinea ; Germ. das sehnige Gewebe. The comprised in the fibrous system may with propriety be referred to two separate and distinct classes. I. Warre risrous oncans.—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 ; 6, fascie or muscular aponeuroses ; c, sheaths of the tendons; d, fibrous coverings of certain 3 €, ligaments; /, tendons. I. YeLLow ELastic FIBROUS ORGANS.— There are certain organs, ex. gr. the yellow ogy (ligamenta subflava) of the spine, ich 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. Ware Fisrovs orcans.— 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 fascice, in the periosteum, and in many tendons, as in those of the obliquus abdominis externus, pectoralis major, &e. 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 ree they observe a parallel direc- tion, whilst in other places they pass in an irre- gular manner, so as to cross end tetetlesd with each other, occasionally constituting, as in the coe od cP mater and of the tendinous centre diaphragm, a intricate net- work of fibres. : ed 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 eive 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 Tsenflamm, who conceives that this tissue is formed by cellular fibres im ated with gluten albumen ; and also by lard, 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 multitade of names which already so much the science of anatomy. as to the existence of an elementary onganic 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. e 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 — on the removal of the extending rce. 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 mater 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 ae apne Ee eye 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 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 shail 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 fascie ; 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 fascie to the skeleton. 2. Fuscie.—The fibrous fascie 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 vagine 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 FIBROUS TISSUE. 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 edema 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 I 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 fibro-serous membranes, or as they are called by Béclard, 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: 1. 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. he funicular and la- minated ligaments are much more universally diffused, assisting in fact in the formation of every joint in the skeleton. cre alll ileal Ni il 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 Muscte. II. YELLow ELASTIC FIBROUS ORGANS.— Tela elastica.) It was justly observed by Bichat that the ligaments placed between the arches of the vertebre differ in their nature from the other ligaments of the body; and moder 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- loge of the air- ; the fibrous envelope of the cavernous bodies of the penis and clitoris, and of the vesicule 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. Tn addition to the parts above named, it is necessary to add that in certain organs where great elasticity is requisite there is a peculiar er cellular substance, which, although it oes not present the dense and fibrous cha- racter, ap) 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 that is remarkable for its extra- ordinary elasticity.* * It is stated by Sir E. Home (Lect. 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 —— 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- che 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 scléreux (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 scléro-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 the Hunterian 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 vertebra 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 nuchea—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 which they contain. Lobstein has also published some observations in the Jour. Univer, des Sc. Méd. on the tissue of the uterus, which he regards as ana- logous to the so-called yellow tissue of the middle arterial coat. * Annales Frangaises et Etrangércs d’Anat. et de Physiol. Jan. 1837. P. 59. 266 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.* Morsip 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—Ist, as an antagonist to muscle, and 2d, in aid of mus- cular action. In the tormer class he places such examples as that of the oyster alluded to in the text, in the latter the ligamenta nuche 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.] FIBROUS TISSUE. 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- Jfication—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. Liston 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, Traité des Malad. Chir. tom, 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, (Legons Orales de Chir. Clin. tom. i. p. 2). The tension and contrac- tion of the palmar fascia, which are usually caused by continued pressare, 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 cavernosum 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. PL FIBULAR ARTERY. oe subjacent bone has been partly that the fungoid disease entirely nated from the periosteum .* alignant fungus occasionally arises from the periosteum. I have seen one case of this disease connected with the tibia, in which amputation was formed, but with an un- favourable result, the patient sinking rapidly from mortification. ra medullary sarcoma that membrane is often involved. teo - sarcoma, according to Howship, Craigie, and Meckel, occasionally has its ori- gin in the periosteum. (R. D. Grainger.) FIBULAR ARTERY, (arteria oneda ; Fr. arttre peroniere; Germ. die Wadenbein- arterie ).—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 pliteus muscle, thence the artery extends ownwards 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 soe tibial, but more especially of the rmer. 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 ius and encased between that muscle and me. Inferiorly it 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 int 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 Jarger size than ™ The result of di ion ind me to supp in many old and intractable ulcers, the fun- excrescences seen on the surface arise either the fascia of the leg or from the periosteum, cage. Begs they are placed on the outer or inner part of limb. : 267 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 llicis proprius, to which in its whole course it gives a liberal supply; also to the fibula and the peronei 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 peronial arteries. Anterior peroneal artery, (arteria peronea anterior and perforans peronea.) This branch gains the anterior surface of the leg by piercin: the interosseous ligament, where it is cove! by the peroneus 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 Sere, when the anterior tibial exhibits this eficiency. Posterior peroneal artery, (A. peronea 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 when 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 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 Trsrat Ar- TERIES. (R. B. Todd.) FIFTH PAIR OF NERVES.—This title is derived from the relation which the nerve bears numerically to the other encephalie 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 ¢rifacial (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 o 6 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,t that animal is provided with an optic nerve, as large as a human hair, and according to Carus{ it joins an optic branch from the fifth, and the two concur to form the retina. In * Anatomie Comparée du Cerveau, &c. + Journal Complementaire. ¢ Journal Compl. FIFTH PAIR OF NERVES. 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 Treviranus* and Serres,t 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:{ 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.}+ However just the estimate of the comparative volume of the nerve in different animals, as here stated, may * Op. cit. + Op. cit. t Desmoulins, Journal de Physiologie, t. ii. Serres, op. cit. § Desmoulins, Anatomie des Systémes Nerveux, &c. Carus, Rudolphi. || Desmoulins, op. cit. Desmoulins, op. cit. ** See Sketches of Nerve in the Ray and Cod, figs. 144, 145. tt Serres, Anatomie Comparée du Cerveau, dans les quatre classes des Animaux Vertébrés. ——S SC AP Fem Vale ee FIFTH PAIR OF NERVES. be, the data, fiom which it is professedly drawn, tay 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 @ priori. Each nerve is com 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, no ganglion, and is destined to volition; they are ee denominated, the former the larger, the ganglionic or the sentient portion, the latter the os 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. e latter assertion, however, is incorrect, the distinction being to be observed as satisfactorily in that class as in any other.+ 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 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 bres cannot without difficulty be separated from ah other and diseotangled, while in another they oda 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 a sketch of fifth nerve in the Turtle, fig. 143. cit. 269 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 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 bcd aes 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,+ the total number of filaments contai 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’Anatomie. t Anatomie 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 Scemmerring + 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- sed, the filaments seem to be equally fine in oth 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 Seem, 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 * Observationes Anatomicz de quinto pari ner- vorum, &c, : + In Ludwig, 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,+ 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 erus 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,t but they have been more parti- * Anatomie Descriptive. t Anatomie et Physiologie du Systéme Nerveux. ¢ Observationes Anatomica. of = Dos FIFTH PAIR OF NERVES. -cularly and accurately described by Palletta.* They are diainuiohed by the latter into supe- rior and inferior, being attached to the crus 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 =m of the lesser packet are perfectly distinct and separated b the interval aorta 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 mes 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 mastication. Palletta+ 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 buceinator, forming the long buccal nerve, he called the former the “ crotaphitic,” and the latter the “ buccinator” nerves. The distri- bution of the lesser packet to the muscles of mastication has been confirmed by Mayot from * Palletta, De Nervis crotaphitico et buccina- torio, an. 1784. Script. Neurol. Min, Select, Lud- wig. t Op. cit. ¢ Commentaries, and Physiology. 271 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 Eschricht® 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 ly 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 iculus 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 si it is necessary that the brain be pre; yy some of the methods recommended for that Emer of which immersion in strong spirit is y 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 lan which the sultioe has found most success- ul has been to commence the dissection early, to return to it frequently, and at each time to ursue it so far and so far me Hal ee 0 ctory. 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 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 ‘ Observationes Anatomice,’ in 1724, and from which Semmerring 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 8 eee 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. FIFTH PAIR OF NERVES. 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 fig. 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. keeles ae ' FIFTH PAIR OF NERVES. the same part as the greater packet, and poste- rior to it. Tce fig. 140). This view of the con- nection of the lesser packet, if confirmed, must lead to interesting results with regard to the rela- tions of thetwo 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 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-ganglionic divisions of the herve seem for the greater part associated in their distribution. 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 references 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 _ a 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 p , 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 sw it be a continuation of the tract from whic’ the nerve appears to arise, or a part of the floor of the ventricle at its upper extremity, con- nected to the attachment of the nerve: the mode in which gat arises in - ee and the Hee pears to author to the opinion that 44 tract to which the aoe tk attached is, in them at least, any thing more than a continuation or VOL. II, 273 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 figs. 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 mo posed: externally the tract corresponds to the peduncles of hecoaabetiats, 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, (figs. 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 ooanritly, 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 méme dans les rongeurs, les taupes, et les hérissons, un petit mamelon ou tubercle sur l’extremité antérieure du bord du ventricule ; mamelon, dans lequel se continuent les fibres posterieures de la cinquitme paire, et de V’acoustique.” 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 figs. 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 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 ina 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 int, before the course of the nerve had 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 aisément suivre son cours entier jusq’au dessous du cété extérieur des corps olivaires ;” this might be, perhaps, interpreted to mean beyond the olivaries, 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- * Anatomie et Physiologie du Systéme Ner- veux, tom, i, p. 107. FIFTH PAIR OF NERVES. 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 also 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.” Cloquet} 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 Gall 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|| 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 medulle ob- longate caudicem conjectus, fere inter olivaria et pyramidatia corpora locatus, quo demum pergat, cum tenuium fibrarum implexus, tum earumdem mollitudo, ne consequerer, omnino came 3” from which it is plain, as has en 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, Semmerring, 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’Anatomie, French edit. t Traité d’Anatomie descriptive. ¢ Anatomie de l’Homme, See note 5, p. 82, op. cit. vol, ii. Observationes Anatomice, FIFTH PAIR OF NERVES. viz.the attachment of the two packets to thesame 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. encephalic connections of the nerve, as detailed, are corroborated by those to be observed in inferior animals. In those Mam- tmalia in which the pons is but little deve- loped, the nerve is attached between that by and the trapezium ; in those instances in which the pons is more so, the nerve is attached, superficially, not actually behind that pat, 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- hence or tubercle, from whence a cord de- scends beneath the trapezium into the lateral _ column of the spinal bulb. This cord is of sige size in many animals; and_in some can seen distinctly, without dissection, upon the surface of the spinal bulb, in consequence of the degree to which it projects: it is well eepeened 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 ns, 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 cineritious stratum, of which the latter consists, being directly connected to the back of the nerve. Birds (fig. 142) the continuation of the nerve Brain and Fifth Nerves of the Goose. 1 Inferior surface of cerebrum. 2 Spinal bulb. 3 Ganglia of fifth nerves, 4 t of nerve from lateral column of the bulb exposed by turning aside the superficial stratum of that oy : 5 First division of the fifth. 6 Second do. Third do. 8 Auditory nerve. On one side (the reader’s right) the non-gan- faced beneath the gan- 275 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 smallness 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, t® 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 276 FIFTH PAIR OF NERVES. " Brain-and Fifth Nerves of the Cod. ‘1 Non-ganglionic portions (on the reader’s left side) separated from the ganglionic and thrown back. 2 Ganglionic portion. a First branches of both portions. b Second do. | ‘immediate apposition and appear to have the same source. Jn the Ray it is different; in it the auditory seems merely a branch of the fifth (fig. 145, 7) given off from its posterior e Third do. d Fourth branch derived from both. e Fifth branch derived only from the ganglionic. Bie third division has been removed on the left side, 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. 145. Brain and Fifth Nerves of the Ray. a Anterior ganglionic portion of the fifth nerve. & 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. Second do. Auditory nerves, the brain, so very much from that in the in- ferior, as it is represented by some to do. — 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- secured by superadded structures. In the second place the trapezium can be regarded only as a superadded structure, and is not among those from which nerves are likely to arise, ing 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- —_ inasmuch as the latter is situate be- ‘ore 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. Serres has mistaken the place of the nerve’s attach- ment in the Mammalia. In conclusion, the representation of the ori- in of the nerve, which ap to the writer to Se 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 ; itcan 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 peeetly originated in the intimate connection nown 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 ies 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, 277 halic portion of the nerve presents within the in, Pe 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 portiow 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 reviously been, but immersed in it ; they are, owever, 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 rtion, 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 Vuarolii, 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 from it by a lamina, of dura mater; it is there contained ina 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, anothemabove- separating them 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 the ganglion, and’sends fibrous-offsets upon Sy cartes weeks roceeding 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 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 the 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 varieties 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 eke is united to the third trunk proceeding rom 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 reached 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 or peripheric portion of the nerve consists of three large trunks or divisions, which are connected, on the one hand by their ramifications, with the FIFTH PAIR OF NERVES. 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 referable; but inasmuch as those which have een selected do not at all adequately express that distribution, and are attended, therefore, with the inconvenience of not 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. he trunks rest partly against the outer side of the cavernous sinus and im 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 eee ————————ee—eEeEeEeEe FIFTH PAIR OF NERVES. 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 diviscon—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- ion 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 altogether 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 from its outset to its final division, except an extraordinary filament described b: __ Arnold, and denominated by him the fecmtedit 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- 279 ture of the tentorium cerebelli, and divides be- tween its laminw 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. The elder 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 lachrymal 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 a very different relations. 1. The frontal nerve 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 asa 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 foramen lacerum. of the orbit, and enters that region through it. It _ continues its course through the orbit to the superciliary foramen and escapes through it to the forchesd. During this cota 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 rm a beneath . = entering, it passes above the origin of the papeelor rectus muscle, and all the other parts 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 nerve. 260 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- bre 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 1 aeeRs 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 tke 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 tonek, 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-trochlear or internal JSrontal. 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 corrugator supercilii, orbicularis, and frontalis muscles, it has received the name of internal Jrontal, in contradistinction to the continued trunk, which is at the same time called external JSrontal. 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- FIFTH PAIR OF NERVES. 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 ow 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 corrugator 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. guments of the eyebrow and forehead ; one of these branches, as described by Meckel runs outward, through the orbicularis, towai 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 rately 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 Semmerting. 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 galli; 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 , 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 Epes 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, 281 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 palpebre, the 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, eat 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 ives off, 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 su rior division of the third nerve; then runs for- ward along the outer side of the optic nerve, and terminates by joining the superior and terior part of the lenticular ganglion. Accord- ing to Bock and Meckel junior, it occasionally ives off a ciliary nerve, and according to eckel senior it is, in rare instances, derived from the third nerve. To the latter statement, however, the author hesitates to assent; it a 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 rior part of the ganglion are also attac! two filaments derived, one from the cavernous ganglion or the carotid plexus ; the other, the constant existence of which has not 282 been yet established, from the spheno-palatine 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 branch, 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 * J. F. Meckel. - FIFTH PAIR OF NERVES. 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 caruncula lachrymalis and the lachrymal sac. Of those ramitications, 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 latteranastomosis 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 naso-palatine of Scar 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 Jachrymal: 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 * The clder Meckel. FIFTH PAIR OF NERVES. arises, for the most part, from the ophibebaie at the same time with its other branches ; J. F. Meckel asserts that it arises more fre- uently from a trunk common to it and the tal; 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 again 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 the spheno-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 josteum, 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- no-maxillary : it might from its destination be appropriately termed temporal: it frequently gives off in its descent a filament, which eS rward, 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 often arises by two filaments, one from the ic, the other from the fourth nerve, and Swan describes this as the normal condition,.— Cruveilhier, Anat, Descr. t. iv. p. 911.—Ep.] 283 nal part of the superciliary arch. They give off oct filaments, which are disesbuted 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 trank 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; itis 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,t 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. e 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 REO 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 P of the fossa it enters the infra-orbital canal, through * De Origine nervi intercostalis. + Roux, Journ. de Méd. t. xciii. ¢ Journ, Comp. t. xxiv. 284 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 will 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, FIFTH PAIR OF NERVES. 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 tem 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 juan 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 thei, 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. 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 hot 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- 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 Fanglion : in other rare cases, according to eckel, 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 vision 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 ches 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 pga 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 of the fifth nerve, because, 1. it is not, as 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 * Mém. de l’Acad. de Berlin, 1794, 285 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 — ne does nd resemble the cerebro-spinal ganglia, the iar aj = ance of hans odio, viz. white Alsinents aetaee 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- a branches of the second division of the fth, 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 continuit of the nerve being altogether Mer teen's: 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 * Tom. ii. p. 396, 286 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. é 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 counected 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 seed and hence is called “ the palatine ;” ut 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. FIFTH PAIR OF NERVES. 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 maxillar 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 rigshey! 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 palate and its muscles. a - ; ag - branches of the to the FIFTH PAIR OF NERVES. The second, the posterior, little palatine nerve, descends at first between the external id muscle and the posterior wall of the antrum, then enters the canal, and esca inferiorly external to the former; it divides into two filaments, one of which is distributed to the soft a the other to the tonsils and arches of the palate. Those branches are accompanied by minute latine 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 osterior extremity of the middle turbinate one. 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 pharyn, 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, _ tothe 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 mucons 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 — from hy eo rote | and thus reach e ior of the septum nasi, become poh legit Pr end lntiehie their direction descend forward along it, between the perios- teum and mucous membrane. The short, lesser, branch : ye very near terior margin o e tum, to which ffs parallel in its ences aoe distri- butes its filaments to the membrane of the posterior part of it: one of them is repre- sented by Arnold as constituting the phar geal branch, 287 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 imferior 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 eee described, first by Scarpa,* and by him denominated the naso-palatine ; it has been also described by J. Hunter,t between whom and sep 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 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-. nents 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, 7A Acad in which is also con~ tained a good representation of the nerve as@ single branch. + Animal Gconomy. 288 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 apes 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- tally* 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 u 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 uadrupeds, the horse e. g. are sufficiently istinct, 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 sing 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. FIFTH PAIR OF NERVES. tube. These branches frequently arise from the ganglion itself by a single filament, de- nominated by Bock the pharyngeal nerve, and represented it Arnold among the 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 Ploquet 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,+ 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. t 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 ; ut 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 conn to the sympathetic, a branch of the former. e posterior branch is also known by other * Journ. Compl. t. xxii. + Journ. Compl. t. xxiv. ¢ Arnold. See lingual branch of third division and chorda tympani, - } ; q FIFTH PAIR OF NERVES. names, viz. the recurrent, the pterygoid, the Vidian, the anastomotic, or ausaia 8. The next branch or branches of the su- perior maxillary nerve are the posterior supe- rior dental. ese 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: are distributed to the buccinator muscle and the mucous membrane of the posterior lateral part of the mouth, to the roots of the ior teeth, the membrane of the maxil- Fyn, and the gam 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. ~ i, course around the antrum the anterior ch 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 off its next regular branch, the anterior superior dental: this descends, from the in ital canal, through one of its own _ mame 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 ndicular of the maxillary bone, wntilit 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. 11. 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 terior nerve does the posterior teeth; it also ives at its termination filaments to the mem- rane 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 branches 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 trank till ater 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 eanal, and escapes into the face through a se e 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. hen 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 deseribed, supplies u 290 the structure of the lid, and anastomoses with the portio dura, lachrymal, and malar nerves, as also with the internal palpebral. The descending or /abial 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 ale 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 prscipally 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 aleque nasi, to the compressor naris, and to the integuments on the dorsum of the nose; the * Die Verrichtungen des fiinften Hirnnerven- paars. FIFTH PAIR OF NERVES. 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 ale 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 ale, 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 knowa 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 ortion posteriorly, in the foramen ovale; it ‘orms, 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. + manjeniteadlceatidiacs the time it has m the cranium. third division of the fifth nerve, after its escape from the cranium, is situate in the superior, posterior, and internal part of the matic fossa; it is placed immediately be- hind the external ptery id muscle, before and somewhat internal to the styloid process of the a bone, internal to and on a line with 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 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 arise; for the most se they are given o! meen Hep 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. — branches are the masseteric, the deep ls, the buccal,and the pterygoid nerves, they are ranged in succession from behind forward, and from without inward ; the first is external and posterior ; to it succeed the tempo- tals, 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 iw, in small, and not unfre- quently wanting. muscular dise 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 com into a vertical lamella. The respiratory appa- ratus varies in structure; in some genera it is composed of vascular ramifications which line acavity into which the respired medium is freely admitted. Others are provided with branchize, adapted to the respiration of water, variously disposed upon the exterior of the body, or concealed internally. The heart or age consists of an auricle and ventricle, oo - ee is mic, or, in other words, receives the blood from the a of respiration, and propels it th e body. The serual ongans vary in their structure in different o 3 in the greater number each individual is possessed both of an ovigerous and impreg- hating 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 uatic. ein separating the Gasteropoda into orders, the naturalist finds in the a 09 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 branchie are at . nee universally referred to as affording a _ convenient basis of classification. We shall . this article follow the arrangement adopted VOL, II, # GASTEROPODA. 377 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,t_and genus Doris, Blainville ; Gasteropodes Dermobranches,} Du- meril ; Gasteropodes Tritoniens, Lamarck. In these the branchiz are symmetrical, as- suming a variety of forms, but always placed upon some pat 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. ist Sub-order, Anthobranchiata,§ Goldfuss; Cyclobranchiata,|| Blainville. ist Fam. Doris. 2d Sub-order, Polybranchiata, Blainville. 2d Fam. Tritonia, fig. 173. 3d Fam. Glaucus, fig. 174. Fig. 173. Order Il. INFEROBRANCHIATA, Cuy. and Blain.) : Syn. Gast. Dermobranches, Dumeril ; Gast, Phyllidiens, Lamarck. n the Inferobranchiate Gasteropods the branchiz 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 * Nudus, naked; branchie, gills. + Tleaug, many ; branchie. t Arp, skin. § re oy a flower. || Kuxaog, a circle. yn 378 are hermaphrodite with reciprocal impregnation, and marine. 1st Sub-order, Phyllidiade, Cuv. 1st Fam. Phyllidia, fig. 175. 2d Sub-order, Semi-phyllidiade, Lam, 2d Fam. Gastroplar, Blainville. 3d Fam. Pleurobranchus, Cuv. Fig. 175. Order IIT. psi Cniptae esol uv, Syn. Chismobranches, Bainville; Gast. Adelobranches,t Dumeril; Gast. Phyllidiens and Laplysiens, Lamarck. In this order the branchie 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. ist Fam. Dikera. 2d Fam. Akera. Order IV. PULMONALIA INOPER- CULATA, (Ferussac.) Syn. Pulmones, Cuv.;{ —Pulmobranches, Blainville; Gast. Trachelipodes,§ Lamarck. The respiratory apparatus is here adapted to the respiration of atmospheric air, and instead of being composed of branchial tufts or la- minz, 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. + Advaros, concealed. $ Pulmo, lungs, $ Tpaxnroc, the neck ; wovs, foot. GASTEROPODA. 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, Geophilide,* Ferussac. 1st Fam. Limar. 2d Fam. Helix. 2d Sub-order, Gehydrophilide,t Ferussac. 3d Fam. Auricula. 3d Sub-order, Hygrophilide,t Ferussac. 4th Fam. Limneus. Order V. PULMONALIA OPERCU- LATA, (Ferussac.) Syn. Pectinibranchiata§ Cuv.; 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. Rigi coe seeps re yes (Cuv. Syn. Trachelipodes, Lamarck ; Monopleuri- pane 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 branchie 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, Pomastomide,{ Ferussac ; Chis- mobranches, Blainville. ist Fam. Turbo, Lin. 2d Fam. Trochus, Lin. 2d Sub-order, Hemipomastomide, Ferussac. 3d Fam. Cerithium, Adanson. 4th Fam. Buccinum, Lin. 5th Fam. Murex, Lin. 6th Fam. Strombus, Lin. 7th Fam. Conus, Lin. . 3d Sub-order, Apomastomide, Ferussac. 8th Fam. : 9th Fam. Voluta, Lin. 10th Fam. 4th Sub-order, Adelodermide, Ferussac. 1ith Fam. Sigaretus, Adanson. * Tn, the earth; qAsw, to love. + M, the earth; vdmp, the water; pirew. t Typec, moist ; pirzw. ecten, -inis, a comb. || 2pay, @ canal, {] Twa, operculum; orosa, mouth, Siphoni- GASTEROPODA. ‘Order VII. SCUTIBRANCHIATAS* (Cuv. . Cervicobranches, Blain.; Chismo- branches, Blain. ; Gast. Dermobranches, Dum.; G. Trachelipodes, Lam. Fig. 176. ———EyEEE S| = eee In this order the structure of the branchie _ is analogous to what has been described in the Pectinibranchiata; but the shell, which in the latter was always turbinated, in the Scutibran- chiata is a mere shield, in which the indications of a spire are very slight or totally deficient. % is never an operculum. The o of both sexes are uni species are 379 2d Fam. Capulus.* 3d Sub-order, Heteropoda+ Nucleobranches, Blainyille. 3d Fam. Plerotrachea, fig. 177. Order VIII. GXPLORRANCHIALS, (Cuy.) Syn. Dermobranches, Dum.; Gast. Phylli- diens, Lam.; Gast. Chismobranches, Blain. In this order the branchie are arranged under the margin of the mantle around the circumference of the body; the shell is a simple shield, either com of one piece, which is never turbinated, or else made up of several divisions. They are all hermaphrodite and self-impregnating. ist Sub-order, Chismobranchiata, Blain.; Cy- clobranchiata, Goldfuss. ist Fam. Patella. 2d Sub-order, Polyplaxiphora,t Blain. 2d Fam. Oscabrion. Cuvier detaches the genera Vermetus, Magi- lus, and Siliguaria 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 neces 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 Tubulibranchiata. Tegumentary system —The skin which in- vests the Gasteropoda varies exceedingly in texture, not only in different species but in dif- ferent parts 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 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 per beneath. In those orders which are provided with shells, the integument which A soe such parts of the body as are exposed when the animal partially emerges from its abode, is thick and spongy, and ve different from the thin fibrous membrane whic 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 Capuloid Gasteropods are thought by Cuvier to be diacious. + Erspos, different ; Tous, foot. $ Morus, many; wdrak, a scale ; hy carry. c 380 scribing it we shall avoid obscurity by applying to its different parts the names ordinarily made use of by anatomists to distinguish the tissues enumerated as composing the human integu- ment. The dermis is an extremely lax and cellular texture, eminently elastic, and so intimately blended with the contractile layers beneath it, that it is difficult to recognise it as a distinct Structure: its great peculiarity consists in the power which it possesses of secreting calcareous matter, which being deposited either in a cavity within its substance, or as is more frequently the case, upon its outer surface, forms a con- cealed or external shell: from this circum- stance, and from the abundant quantity of mucus which it constantly furnishes, we may infer its great vascularity, while the high degree of sensibility which it evidently possesses une- quivocally demonstrates that it is plentifully supplied with nerves, although the existence of a true papillary structure cannot be satisfac- torily distinguished. The colouring pigment likewise exists, as is evident from the brilliant markings which are often met with in some of the more highly coloured species; but there is @ circumstance in connection with this rete mucosum which requires particular mention, as it will enable us afterwards more clearly to ex- plain the formation of shells; the pigment is not merely a layer which serves to paint the surface of the body generally, but appears ra- ther to be an infiltration of the lax tissue of the cutis with coloured fluid, which is poured out in great abundance at particular points, espe- cially around the margin of the shell, and there being mixed up with the calcareous matter se- creted by the collar, its tints are transferred to the exterior of the shell itself, tinging it with similar hues. The epidermis is evidently defi- cient, its place being supplied by the viscid matter with which the surface of the body is continually lubricated. The muciparous crypts destined to furnish the copious supply of glairy fluid with which the skin is so largely moist- ened, have not been detected, but the pores through which it exudes are sufficiently distinct. It is in connexion with the needful diffusion of this secretion over the entire animal, that the skin of the terrestrial species, as the Slugs and Snails, is observed to be deeply furrowed by large anastomosing channels, formed by the ruge of the surface, and serving as canals for its conveyance by a species of irrigation to every point. No pilous system, properly so called, exists in any of the Gasteropods, the hairy covering of many shells being, as we shall presently see, of a widely different nature. From the modifications observable in the structure of the integument, it is not to be won- dered at that names have been applied to diffe- rent portions, which it will be useful to notice, especially as they are not unfrequently used in a confused and unprecise manner. That por- tion of the skin which is more immediately conneeted with the secretion of the shell, in such Gasteropoda as are provided with a de- fence of that description, has been termed the mantle, and in certain instances, from the mode GASTEROPODA. in which it seems to form a special covering to a part of the body, it has some claim to the name; the mantle is, however, extremely varia ble, both in position and arrangement. In the Nudibranchiata, which have no shell, it cannot be said to exist, as no fold of the integument or defined margin indicating a portion deserving of a distinct appellation can be detected. In the Tectibranchiata the mantle is a small trian- gular fold of the integument on the right side of the body, inclosing a rudimentary shell, and serving as a covering to the subjacent branchiz. In the Inferobranchiata it invests the whole of the back, and forms a fold around the margins of the body, beneath which the branchie are found ; whilst in all the conchiferous Gastero- ods it lines the interior of the shell, whatever its shape, forming a distinct fold or thickened rim around its aperture, to which when much developed, as in Helix, the name of collar is not improperly applied. In the naked terrestrial species the mantle consists of a thickened portion, occupying a variable position on the back, and more or less defined by a distinct margin; it is here not un- frequently termed the corselet, and generally contains a calcareous plate. In Vaginula it covers the whole of the back; in Limaz it occu- ies only its anterior portion; in Parmacella it is found in the middle of the dorsal region, whilst in Testacella it is placed quite poste- riorly in the vicinity of the tail; yet whatever its situation, shape, or size, it is the immediate agent in the formation of the shell, and as such we have deemed it necessary to be thus precise in describing the different aspects which it assumes. Growth of shell—The varied and beautiful shells that form so important a part of the inte- gument of many individuals belonging to this order, however they may differ in external form and apparent complication, are essentially simi- lar in composition and in the manner of their growth, These calcareous defences, although serving in many cases as a support to the ani- mal, from which important muscles take their origin, differ widely from the internal skeletons of vertebrate animals, being mere excretions from the surface of the body, absolutely extra- vital and extra-vascular, their growth being en- tirely carried on by the addition of calcareous. particles deposited in consecutive layers. The dermis or vascular portion of the integument is the secreting organ which furnishes the earthy matter, pouring it out apparently from any part of the surface of the body, although the thicker portion, distinguished by the appellation of the mantle, is more especially adapted to its pro- duction. The calcareous matter is never depo- sited in the areolz of the dermis itself, but ex- udes from the surface, suspended in the mucus which is so copiously poured out from the mu- ciparous pores, and gradually hardening by ex- posure; this calciferous fluid forms a layer of Shell, coating the inner surface of the pre-exist- ent layers to increase the size of the original shell, or else is furnished at particular points. for the reparation of injuries which accident may have occasioned. It is to the investiga- A animal; or, as is the shell is formed of several pieces articulated GASTEROPODA. tions of Reaumur that we are indebted for our knowledge concerning this interesting process, and subsequent writers have added little to the information derived from his researches; in order, however, to lay before the reader the principal facts connected with this subject, we shall commence with the simplest forms of the process, and gradually advance towards such as are more complicated and less easily under~ The shells of the Gasteropoda are of two kinds, some being entirely concealed within the substance of the mantle, and consequently internal, whilst others are placed upon the sur- face of the body external to the soft integument. In the former case the shell is uniform in tex- ture and colourless ; in the latter, its develope- ment is much more elaborate, and it is not un- frequently moulded into a great diversity of forms, and painted with various tints, which are sometimes of great brilliancy. The internal or dermic shells are found in many of the pulmo- nary and tectibranchiate orders, and possess but little solidity; although inclosed in the substance of the mantle, they are so little adhe- rent, that when exposed by an incision they readily fall out of the cavity in which they are lodged, and from which they are apparently quite detached. Their substance is generally calcareous, but in many instances, as in Aplysia, the shell is of a horny texture, being transpa- rent, flexible, and elastic, as is the gladius of many of the Cephalopod Mollusca. In all cases horny or calcareous plates of this descrip- tion are found to be composed of superposed famellw, which are successively secreted by the floor of the cavity in which they are contained, the inferior layer being always the largest and most recent. These shells, therefore, may be con- sidered as merely formed by the deposition of successive coats of varnish, which become indu- rated, and the simple manner of their growth will best exemplify the mode in which more compli- cated shells, whatever be their form, are con- structed. External shells present an endless di- versity of figure, and some classification of their principal forms will facilitate our contemplation of the peculiarity observable in each. The con- cealed shells, which are merely the rudiments of what we arenow considering, are so small in com- parison with the size of the body, that they can only be looked upon as serving for the protec- tion of the more important organs, namely, the heartand respiratory apparatus, which are placed beneath them, but the external shells, from their great developement, are not merely a partial protection to the animal, but in most cases constitute an abode into which the creature can retract its whole body. The external shell consists generally of one piece, the form of _ which may be symmetrical, in which case it is a cone or disc simply covering the back of the erally the case, the shell may be more or less twisted around a central axis, forming a convoluted, turbinated, or spiri- valve shell. In one genus only, Chiton, Lin. with each other, and covering the surface of the back 38% The shell of the Patella, a section of which is represented in fig. 178, is a simple cone placed bt A the back of the creature, which it com- Pp at § covers, and upon which it is evidently moulded. On making a section of the animal, as in the figure, the shell is found to be entirel lined by the mantle a, b, by which it is coasted: Fig. 178. That the whole surface of the mantle is capable of secreting the calcifying fluid from which the shell is formed, is distinctly proved by the manner in which a fracture or perforation in any part is speedily repaired by the deposition of a patch of calcareous matter beneath it, but in the ordinary growth of the animal the differ- ent portions of the mantle execute different functions. It is obvious that the enlargement of the body of the patella, as its age increases, must necessitate a corresponding enlargement of its habitation, and this is principally effected by additions of caleareous matter in succes- sively larger rings around the mouth of the shell only ; the great agent therefore in forming the shell is the margin of the mantle, b, b. This hangs loosely as a fringe near the mouth of the shell, and being moveable at the will of the animal, the calcareous matter which it pre- eminently furnishes may be laid on in succes- sive layers to extend the mouth of its abode ; and these consecutive additions are indicated externally by concentric lines running parallel with the circumference of the shell, the num- ber of which necessarily increases with age. Whilst the abode of the creature is thus en- larged by the deposition of shell from the vas- cular and spongy margins of the mantle, the office of the rest of that membrane is reduced to the increase of its thickness, depositing succes- sive coatings of calcareous particles, which are laid on to its inner surface, and when a section of the shell is made (f//, these last-formed strata are readily distinguishable by their whiteness and different arrangement. So far the produc- tion of an external shell is entirely similar to what we have met with in the formation of the internal defences of the naked Gasteropoda, yet in other respects the former are much more ela- borately organised. In the first Mager many of them are adorned externally with colours, not unfrequently arranged with great regularity and beauty ; these tints belong exclusively to the outer layers of the shell, that is, to those formed by the merging of the mantle, and are produced by a glandular structure appropriated to the secretion of the colouring matter, which onl exists in the vascular circumference of the at 382 ciferous membrane. The colouring matter becomes thus incorporated at definite points, with the cement by which the shell is extended, and is arranged in various manners according to the position of the secreting organs which furnish it. Another peculiarity which distin- guishes external shells is that their outer sur- face is often invested with a membranous layer, called the epidermis, which having been re- garded by some authors asa part of the true integument of the body, has given rise to the supposition that all shells being placed between two layers of the skin were in fact internal, the difference between the one and the other con- sisting merely in the extent of development. In support of this opinion reference has been made to the great thickness of this epidermic coat, which not unfrequently is such as to give to the surface of the shell a felted or pilous ap- pearance ; but if such an idea were correct, it is evident that the epidermis must be formed prior to the deposit of calcareous matter be- neath it, which observation has disproved, in- asmuch as those shells in which the epidermic covering is most dense and shaggy are found whilst in ovo to be without such an investment. The so-called epidermis, therefore, whatever may be the aspect which it presents, whether it be, as is usually the case, a brittle lamella en- crusting the shell, or a flocculent and pilous covering, is evidently inorganic, being merely a crust of inspissated mucus, originally secreted with the calcareous particles, and forming when dry a layer encrusting the surface of the shell. There is yet another structure common to shells of this class, of which it remains to speak, namely, the enamel or pearl, which lines such por- tions of them as are immediately in contact with the body of the animal ; this polished material may be likened to the glazing of an earthen- ware vessel, and is a varnish produced from the general surface of the mantle, by some mo- dification of its secretion the nature of which is unknown, and spread in successive coatings over the more coarse calcareous matter, where- ever such a polish becomes needful. Having thus briefly described the origin of the different parts ofa shell in the simple form which we have chosen as an example, we shall now proceed to examine the structure and mode of growth in others of a more complicated aspect. The majority of the Gasteropoda are furnished with a shell which has been denominated spiri- valve. Let the reader imagine the shell of the Patella to be lengthened into along cone, which, instead of preserving its symmetrical form, is twisted around a central axis, and he will imme- diately understand the general arrangement of the parts in shells of this description. The cause of such an arrangement is owing to the shape of the body of the animal inhabiting the shell, which, as it grows, principally enlarges its shell in one direction, thus of course making it form a spire modified in shape according to the de- gree in which each successive turn surpasses in bulk that which preceded it. The axis around which the spire revolves is called the columella, and the mode of revolution around this centre gives rise to endless diversity in the external GASTEROPODA. form. In the spirivalve-shelled Gasteropoda, as in those last described, we find a difference in structure between that part of the mantle which envelopes the viscera, and is always concealed within the cavity of the shell, and the more vascular portion placed around its aperture : the former is thin and membranous, its office being merely that of thickening the shell by the deposition of successive caleareous strata applied to its inner side, and of product the pearly lining which smooths and polishes the interior ; the latter part of the mantle is thick, spongy, and coloured, secreting largely the cal- careous particles with which the progressive amplification of the shell is effected : this por- tion (fig. 179, c,) from its thickness, and the Fig. 179. manner in which it usually surrounds the en- trance to the shell, is generally termed the col- lar. In such species as inhabit coloured shells we may observe upon the surface of the collar (fig.179, d, ) pabahies of different colours corres- ponding in tint with the various hues seen upon the exterior. These spots supply the pigment, which being mixed up with the earthy cement serving for the enlargement of the shell stains it with a corresponding tint. In many instances, as in the figure, the colours are continually secreted by the dark spaces, d, causing the painted bands which they produce to wind un- interruptedly in the direction of the convolu- tions of the spire, and they may be seen gra- dually to increase in breadth as the size of the animal enlarges ; but more frequently it happens that the colouring matter is only furnished at stated periods, and in such cases of course the shell will be marked with spots, the intervals be- tween which will be regulated by the frequency ofthe supply. It will be seen that bya combina- tion of these circumstances it is easy to explain how every variety of marking may be produced, The most conspicuous exception to the gene- ral process by which shells are painted, is met with in the porcellaneous Couries ( Cyprea ), which at various periods of their growth could scarcely be recognised as belonging to the same genus. In the young animal the enlargement of the shell is effected in the ordinary manner, and its colours are supplied from the surface of the collar: in the mature state, however, these shells are coloured in a very different manner, and acquire at the same time a great increase of thickness; this is effected by the enormous de- velopment of the ala of the mantle, which in the full-grown animal become so much ex- tended, that when the creature is in motion they are laid over the external surface of the shell so as entirely to conceal it. These ale contain patches of pigment which secrete colours en- tirely different from those contained in the collar, and from their whole surface exudes a i a GASTEROPODA. calcareous varnish, which being laid over the exterior of the old shell completely conceals the original markings ; these, however, may be again exposed on removing with a file the outer crust: a line, which is generally very distinctly seen running longitudinally along the back of the shell, indicates the spot where the edges of the two ale of the mantle met during the com- pletion of this singular process. Such shells are remarkable from the circumstance of having their thickness increased by additions to the outer as well as to the internal surface. In terrestrial shells it is only when they have arrived at their full growth that a rim or margin is formed around the aperture, which serves to Strengthen the whole fabric; but in marine shells, which attain to much larger dimensions, the growth is effected at distinct periods, each of which is indicated by a well-defined margin, and these ridges remaining permanent, the suc- cessive stages of increase may be readily seen. Ateach suspension of development, it is not unusual to find spines or fringes, sometimes differently doloored: from the rest of the shell, and not unfrequently of considerable length. In fig. 180, which represents the shell of Murex cornutus, the nature and arrangement of such spines is well exemplified. They are all formed by the margin of the mantle which shoots out into long fringes, encrusting themselves with a shelly covering ; each spine therefore is at first hollow, and if in many species they are found solid, it is because the original cavity has been gradually filled up by the deposition of earthy matter within it. The syphon with which many Conchiferous Gastero} are provided is pro- duced in isely the same manner, and its identity in with the other spines covering the surface of the shell is in the annexed figure sufficiently obvious. In many species, as in the beautiful Turbo scalaris, (fig. 181,) the epocha of growth are only indicated by ridges surrounding the shell at regular intervals, each of which originally terminated a fresh augmen- tation of its size. It is difficult to imagine by what influence these creatures are induced to enlarge their habitations at such regular inter- vals, terminating each operation by a similar margin ; some authors imagine that each time the creature emerges from its abode a fresh addition is made ; others that it is dependent upon the temperature or state of the seasons, but without sufficient grounds for either of these assertions; it seems more probable therefore that the growth of the body gradually rendering the former dimensions of the shell incommo- dious from time to time renders these pe- riodical enlargements necessary. ‘Although shells are evidently inorga~ nic and extra-vascu- lar structures, it is now universally con- ceded that their in- habitants have the power of removing portions which may obstruct their growth, or needlessly infringe upon the limits of their abode. In the Murices we have in- disputable evidence of this fact in the removal of such spines as would interfere with the revolutions of the shell around the columella, and in Conus and similar genera a like faculty enables the animals to thin the walls which bound the inner whirls when their original thickness is rendered un- necessary by the accession of new turns. Such a solvent power indeed is not only exer- cised upon their own habitations, but many Gasteropods are able gradually to bore holes in other shells, or perforate the rocks upon which they reside to a considerable depth. The mode in which this is effected is, however, still a mystery; some authors ascribe it toa power of absorbing their shells, an expression the vagueness of which is sufficiently evident ; others ascribe it to some acid secretion at the disposal of the animal; yet although this ex- planation is certainly plausible, when we reflect that the very structure which secretes this sup- posed acid is itself the matrix of such abundant alkaline products, it is not easy to imagine how the same structure can at the same time furnish such opposite materials. As we should expect from the mode of its het the shell throughout all the Conchi- erous class is composed of earthy matter, cemented together by an animal substance easily separable by the action of acids. In the porcellaneous shel!s the animal matter exists in much less quantity than in those of a fibrous texture ; in the former, indeed, Mr. Hatchett found that when the carbonate of lime, of which the earthy portion is almost entirely formed, is dissolved even by very feeble acids, little or no vestige of any membranous struc- ture could be perceived, nor indeed could any be detected, but by the small portion of animal coal which was formed when these shells had been exposed for a short time to a low red heat; in others however, as the Patellw, a sub- stance was left untouched by the acids which had the appearance of a yellowish transparent jelly, by means of which the earthy matter had | been, as it were, cemented together. On examining minutely the mechanical a- rangement of the layers of which these shells. are com » it is found to vary in different kinds, and from this circumstance the fossil 384 conchologist may derive important information in examining mutilated remnants sometimes so plentifully met with in calcareous strata. The simpler shells (Patella, Fissurella) are formed of very thin, compact, and parallel layers, whilst in others three distinct strata of fibres, each of which assumes a different direction, may be observed. The fibres composing the external layer are disposed perpendicularly to the axis of the shell. In the middle stratum the fibres are placed obliquely and are slightly twisted, but so arranged that each meets at an obtuse angle the extremity of one of the fibres composing the outer layer, and in the internal stratum they again assume a perpendicular direction. Such a disposition of the fibres, which is met with in all Siphonibranchiate shells, is eminently calculated to resist ex- ternal violence in whatever direction it may act, and greatly contributes to the solidity of the whole fabric. Operculum.—Many of the spirivalve Gaste- ropoda, especially such as are aquatic, are provided with a calcareous Plate, which is placed upon the posterior surface of the body, and closes accurately the mouth of the shell, when the animal is retracted within it. The texture of the operculum is sometimes horny, but it is more frequently calcareous and of a stony hardness, its contour being accurately adapted to the orifice. It is composed of rallel fibres disposed perpendicularly to the ase of the shell, and deposited in successive layers around an axis, so as to give to the whole structure the appearance of a solid spirivalve, as may readily be seen on removing it from the animal and examining its inner surface. This has been looked upon by some zoologists as analogous to the second valve of bivalve Mollusca, to which, but for its want of a ligamentous attachment, it certainly bears a distant resemblance. The deciduous operculum of terrestrial Gasteropoda, or epiphragma, as it is usually called, is a widely different structure, being merely an inspissated secretion, with which, during the period of hybernation, the entrance to the shell is closed; and on removing the outer plate, not unfrequently a second or even a third similar membrane will be found within, forming additional safeguards against intrusion or the vicissitudes of temperature. During the progressive growth of the shell the animal contained within it necessarily changes its original position, advancing gra- dually as the body enlarges from the earliest formed spires towards the aperture, as may easily be proved by sawing off the apex of a spirivalve shell containing the living animal. This circumstance is remarkably conspicuous in some of the Bulimi ( Bulimus decollatus ), enabling the occupant, as it grows, to break off the turns of its spire which first contained it, so that at the latter period of its life it does not retain any part of its original shell. The mode in which this advancement is effected is a subject of much curiosity, as it involves a power of detaching the muscles connecting the creature with its abode, from the place GASTEROPODA. where they were originally fixed, and forming a new connexion with the shell; but whether this is effected by the remoyal of the original fibres and the production of others more ante- riorly, as is believed by some, or whether, as is more probably the case, the creature has a power of changing the attachment of its re- tractor muscle at pleasure, is still a matter of uncertainty, Organs of digestion —We shall not be sur- prised to find that in a class so extensive, and composed of individuals living in such diver- sified circumstances, the alimentary organs are much modified in form in different species, according to the nature of the food with which they are nourished. Mouth.—In most instances the mouth pre- sents the appearance of a retractile proboscis, which can S protruded or shortened at the will of the animal, but unprovided with jaws or any apparatus for mastication ; it is in such cases a muscular tube, formed of longitudinal fibres prolonged from the common parietes of the body, and of circular muscles, the former serving for the retraction of the orgau, the latter causing its elongation by their successive action; by means of this simple structure every movement requisite for the prehension of food is effected. At the bottom of the tube is a narrow vertical aperture, the edges of which are slightly cartilaginous, and behind this is the tongue armed with spines variously dis- posed; the aliment therefore, having been forced by the contractions of the proboscis through the aperture at its termination, is re- ceived by the tongue, and by the aid of the latter organ is propelled into the csophagus without mastication or any preparatory change. In Buccinum and other syphoniferous ge-. nera, the structure of the proboscis is much more complicated and curious, (fig. 182.) “ The proboscis, which carries with it the cesophagus in its different states of protrusion, is organised with wonderful artifice, being not only capable of flexion in every direction com- bined with limited power of retraction or elongation, but it can be entirely lodged in the interior of the body, folded within itself, so that that half which is nearest the base en- closes the other portion: from this position it is protruded by unfolding itself like the finger of a glove or the tentacle of a snail, only it is never completely inverted. We may repre- sent it as composed of two flexible cylinders (fig. 182, a, b,) one inclosed within the other, the upper borders of which join, so that by drawing outwards the inner cylinder, it is elongated at the expense of the other, and on the contrary, by pushing it back, the internal cylinder becomes lengthened by its shortening. These cylinders are acted upon by a number of longitudinal muscles (c,c), all very much divided at each extremity, the internal or su- perior divisions being fixed to the paeen of the body, whilst at the other end they are attached to the inner wall of the internal tube (a) of the proboscis, along its whole length, extending even to its extremity ; their action is obyiously.to draw the mner cylinder, and con- ee _ imated by strong muscular fibres, GASTEROPODA. uently the entire ~ te 84 inward. This ing done, a great rt of the inner sur- ce of the inner cy- linder becomes a part , of the external surface of the outer cylinder, whilst the contrary oc- curs when the pro- boscis is elongated and protruded. The elongation of the inner cylinder by the unfolding of the outer, or what is the same thing, the pro- trusion of the sates cis, is effected by the intrinsic annular mus- cles which assist in forming the organ ; they surround it throughout its whole Cak: and by their suc- cessive contractions force it outwards; one espe- cially, seen at b, placed near the junction of the extremity of the onter cylinder with the inte- guments of the head, which is stronger than the rest. When the proboscis is protruded, its retractor muscles acting separately, bend it in every direction, being in this case antago- nists to each other. The internal cylinder incloses the tongue (f), the salivary canals (e), and the greater part of the esophagus (d), but its principal use is to apply the extremity of the tongue to such objects as the animal would suck or erode by its armed surface. In Aplysia, Akera, and others, the mouth consists of a fleshy mass of considerable strength, to which are attached muscular bands eeding from the sides of the body, serving for its movements, some drawing it forwards whilst others retract it, but there are no jaws nor anything equivalent to them, except the cartilaginous hardness of the lips. But in such of the Gasteropoda as devour vegetable matter, the mouth, instead of being a proboscis, consists of a strong muscular cavity, inclosing a dental apparatus adapted to the division of the food. . the Snail, Slug, Limneus, Planorbis, &c., this is a single cres- cent-shaped horny tooth, attached to the upper surface, and furnished along its opposite edge with sharp points, separated by semicircular cutting spaces, admirably adapted for the di- vision of vegetable food. The dental organs of Tritonia and Scyllea are, however, still more perfectly contrived for such a purpose. The muscular mass of the mouth is strong and powerful, but instead of the single tooth of the Snail, it is armed with two cutting blades (fig. 183, 6, 6), horny in their texture and exceedingly sharp, resembling * ae Oe a pair of strong curved shears, from which in fact they only differ in the mode of their union, the spring of the one being q replaced by an articulation (c) inclosed in a synovial capsule. These blades are approx- few ‘ig. 183. animal structures can resist their edge. The lips (h), which are placed in front of these teeth, are strong and very flexible, forming a muscular tube, by means of which the food is’seized and brought within the power of its formidable jaws, and then the divided morsels, being seized by the horny teeth which invest the tongue (d), are conveyed into the esopha- s. Tongue.—The tongue in these Mollusca is generally a very important organ, serving not only as a necessary auxiliary in deglutition, but often as a means of eroding the food: in fact, in one tribe only, Thethys, is it found to be deficient. In most of the proboscidean s cies the tongue is short, and covered with sharp, horny, and recurved spines, which, seizing the morsels of food en into the mouth by a sort of peristaltic motion, push it backends into the esophagus. In some ge- nera which have no proboscis, the tongue is of extraordinary length; thus in Haliotis it is half as long as the body, and in Patella, Turbo, Pica, and others, it much exceeds in length the entire animal. The tongue of Pa- tella, which is three times the length of the body, is represented at fig. 184 ; it is supported by two cartilaginous pieces (b, b) placed on each ° Fig. 184. side of its root; from these arise strong and short muscular bands, which wield the or- gan. The surface of this singular tongue, a magnified view of which is given at B, is armed with minute though strong teeth, placed in transverse rows and arranged in three series; each central group consists of four spines, while those on the sides con- tain but two a-piece. It is only at its an- terior extremity, however, that the tongue so. armed presents that horny hardness needful for the performance of its functions, the posterior 386 part being comparatively soft; it would seem, therefore, that in proportion as the anterior part is worn away, the parts behind it assume gradually the necessary firmness and advance to supply its place. The action of this curious instrument is as follows :—in the upper part of the circumference of the mouth we find a semicircular horny plate, resembling an upper jaw, and the tongue, by triturating the food against this, gradually reduces substances how- ever hard. On opening the Patella, the tongue is found doubled upon itself, and folded in a spiral manner beneath the viscera. The tongue of Oscabrio resembles that of the Patella, except in its armature, being fur- nished on each side with a series of hooked and three-pointed scales, and another set of long, sharp, and recurved spines, whilst its centre is simply studded with tubercles. In Turbo pica the scales, which are cutting and denticulated, are arranged transversely along its surface. The tongue of Buccinum (fig. 182, 7’), is placed at the extremity of the proboscis, form- ing a most extraordinary apparatus, capable of destroying by its constant action the hardest shells; externally it resembles rather a mouth than a tongue, being divided into two lips, each of which is studded with sharp horny teeth. These lips are supported upon two cartilages which occupy the anterior half of the proboscis, and are moved upon each other by strong muscular fasciculi (h) in such a manner that the spines which arm the surface of the organ are alternately erected and depressed by their action, a movement the constant repe- tition of which soon wears away the substances upon which it is made to act. This spiny tongue is situated just within the entrance to the csophagus (d), and besides acting upon foreign ies will materially assist in pro~ pelling the food into that tube. ’ In other Gasteropods the tongue is short and merely an organ of deglutition: thus, in Aplysia it is broad, heart-shaped, and studded with sharp points. In Onchidium and Doris, the surface is marked with transverse grooves, which are crossed at right angles by others of great fineness. And in the Snail and Slug, in which the surface of the tongue is similarly marked, the strie are so delicate that they can only be seen with a microscope. Alimentary canal.— We shall commence our description of the intestinal canal of the Gasteropod Mollusca by the examination of the simpler forms which it presents. In the Snail (fig. 190), the whole alimentary tube (e, 4s & rs is thin and membranous. The stomach, which is merely a dilatation of the cesophagus, is semitransparent, but studded with opaque points and internally folded into delicate longitudinal plicee. From this arises an intestine, of considerable length, without ceca, valves, or remarkable appearance inter- nally, except near its termination, where the orifices of minute follicles may be detected ; the intestine having performed several con- volutions enveloped in the masses of the liver, with which it is connected by cellulosity and numerous vessels, at last runs along the GASTEROPODA. margin of the pulmonary cavity, close to the orifice of which it terminates. In Vaginulus the arrangement is nearly similar (fig. 189, g,h,i.) In Tritonia and Doris the structure of the digestive tube is equally simple, and in these as well as in the majority of the Gaste- ropoda the only remarkable differences are found in the proportional size of the stomach and the length of the intestinal convolutions. In Doris we find near the orifices by which the bile is poured into the stomach, an aper- ture communicating with a round vesicle or cecum, the inner surface of which is evidently glandular, and from its large supply of blood derived from one of the hepatic arteries, pro- bably furnishing an abundant secretion ana- logous to that of the pancreas. In Phasia- nella the stomach is very voluminous and sacculated internally. In Buccinum the di- gestive apparatus is more complicated in its structure. The @sophagus commences, as we have already seen, at the extremity of the pro- boscis, and of course follows all the motions of that organ; when the proboscis is protruded in search of prey, the gullet is straight and adapted to the reception of food ; but when the proboscis is retracted within the body, the cesophagus is bent upon itself, so as to be partially contained within the proboscis, whilst the greater portion is folded beneath that organ in its retroverted state. After making another fold it dilates into a small crop, the lining of which is pleated in the direction of its axis, and to this succeeds the stomach, which isa moderately sized round cavity, irregularly ru- gose internally. The intestine is very short, and has a small cecum appended to its side ; it terminates in a capacious rectum, placed, as is invariably the case, in the vicinity of the respiratory cavity, and having its lining mem- brane gathered into prominent longitudinal ruge. Many of the Gasteropoda are provided with several digestive cavities, resembling in some degree the stomachs of ruminating Mam- malia. In Janthina, which is furnished with a proboscis like that of the Buccinuwm, the cesophagus arising from this terminates by a narrow slit in a membranous cavity or first stomach, to which succeeds a second, having thicker walls and plicated internally. The in- testine is extremely short, terminating as usual in the neighbourhood of the respiratory cavity. In Pleurobranchus the resemblance of the stomachs to those of a ruminating quadruped is very striking. The first stomach (fig. 185, a), which is membranous, receives the bile by a large orifice (b) placed near its communi- cation with the second digestive cavity (c), which is smaller and more muscular; to this succeeds a third (d), the sides of which are gathered into broad longitudinal lamella, pre- cisely similar to those of a ruminant; and to render the analogy still more perfect, a groove is found running along the walls of the second cavity from one orifice to the other, apparently subservient to rumination. The fourth stomach (e) is thin, and its walls smooth, This animal lives on Alcyonia and small Zoo- phytes. | ternally, a strong GASTEROPODA. Fig. 185. Many Gastero} which devour shell-fish and other hard materials have a true gizzard adapted to break in pieces such food; this is the ease with Thethys, an animal whose mouth is totally desti- tute of dental organs, but their want is supplied by a fleshy gizzard resembling that of a bird, having its interior lined with a dense cartilagi- nous membrane, like that which lines the gizzard of graminivorous fowls, and in its cavity shells of Mollusca and Crustaceans are found comminuted by its action. In Limneus we find a gizzard strictly analogous in structure to that of a granivorous bird : it presents two dilatations, one at the cardiac, the other at the pyloric extremity, whilst the middle portion is ape two strong mus- cles, united at the sides by tendinous bands. The gizzard of Planorbis is precisely similar to that of Limneus. In Onchidium the muscular gizzard is followed by two other stomachs, the lining membrane of that which immediately succeeds it being gathered into large folds, which must greatly retard the pas- sage of the aliment; while the third cavity, which is short and cylindrical, is likewise lined with a membrane folded into more delicate plice, affecting a longitudinal direction. There are some families in this class which are provided with a still more elaborate appa- ratus for the preparation of their food, their stomachs being armed internally with teeth variously disposed, and on many accounts extremely curious. In all the Bulle (Akera) the gizzard contains three plates of stony hard- ness attached to its walls, and so disposed that they are evidently powerful ration of the fe Fig. 186. ents in the tritu- . In Bulla lignaria (fig. 186) two of these teeth are placed on either side of the gizzard, into the cavity of which they project, and are united to Tarke other by strong muscular bands; the third piece is smaller than the other two, \ but similarly imbedded in radiating muscles, whose action must powerfully grind down the substances which . come under the influence of this singular mill. In the other Bulle the structure of the gizzard is the same, but the bony plates differ slightly in form and arrange- ment. In all, however, the nts of shells and ae _ substances found in it attest the efficacy Ds CRTs The gizzard of Scyllea (fig. 187, e) is, ex- y cylinder, and when this is opened there are found, firmly im- 387 bedded in, its muscular walls, twelve horny plates, which are extremely hard and as sharp as the blades of a knife; their edges are dis- Fig. 187. posed in the direction of the axis of the organ, and as they project considerably into its cavity, their action upon the contents of the gizzard must be sufficiently evident. Aplysia, however, furnishes us with the most curious form of these stomachal teeth. The esophagus, which is comparatively narrow at its commencement, soon dilates into a capa- cious crop, which is generally found filled with pieces of fucus and the fragments of shells. To this crop succeeds a short cylindrical gizzard with strong and muscular walls, and after the gizzard we find a third stomach which leads to the intestine. On opening the gizzard and third stomach (fig. 188) they are found to have their 388 interior armed in a manner which is probably unique. The sides of the gizzard (b) are covered with pyramidal plates of a rhomboidal figure, the apices of which resemble the tubercles found upon the grinding surfaces of the human molar teeth. Of these there are twelve larger plates arranged in quincunx, besides several smaller ones placed near the entrance of the organ. These teeth are of a horny nature and formed of laminz parallel to their bases: their adhesion to the surface of the lining membrane is so slight that they are detached by the slightest effort, without leaving any trace of membrane or other bond of union, the place of their attachment being only indi- cated by a smooth and prominent surface, corresponding in shape to the base of each tooth. The apices of all these teeth meet in the centre of the gizzard, and whatever passes through that cavity must be bruised by their action. The third stomach (d) is armed with teeth of a totally different nature. These are little conical hooks (c) attached to one side of the organ only, and as little adherent in the dead animal as are the pyramids of the gizzard towards which their points are directed. In the figure many have fallen off, leaving slightly elevated spots indicative of the place of their attachment. Near the pylorus is a large aper- ture communicating with a cecum of consider- able size (f), evidently identical with the spiral cecum of the Cephalopoda both in its position and relation to the insertion of the biliary canals (e), forming, as in Fishes, the rudiment of a pancreas. From the orifice of the cecum a ridge is prolonged into the com- mencement of the intestine (g). Accessory glands.—The auxiliary chylopoietic secretions found in the Gasteropoda are gene- rally only two, the salivary and the hepatic. In some rare instances already adverted to, as in Doris and Aplysia, we may likewise add the pancreatic furnished by the coeca, which in those genera terminate in close vicinity with the ducts issuing from the liver, and which, from every analogy, represent the pancreas of vertebrate animals. The salivary glands are constantly present and seem to present a size and importance corresponding with the mode in which the mastication of the food is accomplished. In those genera which are provided with a cutting apparatus placed in the mouth, they are very largely developed, as also in most of the proboscidean species, and it is only in the Cyclobranchiate order, where the long spiral tongue is used rather for the abrasion than the mastication of the food, that they become small, and, in a very few instances, undistinguishable. In fig. 190, which represents the viscera of the Snail, these glands are marked with the letters 44, and this engraving will give a good idea of the general structure which they present, and of the ordinary termination of the ducts which pour the saliva into the oral cavity. The glands are placed along the sides of the stomach, which they partially invest, and sometimes those of the opposite sides are intimately united GASTEROPODA. with each other; their colour is whitish and semi-transparent, and they are formed of small lobes, which, in many species where their texture is less compact, may be distinctly seen to be formed of the ramifications of their arborescent ducts, each ultimate division of which is terminated by a secreting granule. Tn Vaginulus (fig. 189) the salivary glands are small, but in addition to the ordinary struc- ture (f°) we find an additional tube or slender cecum (*/'), which, lying at first upon the stomach, passes through the nervous collar to join the duct by which the saliva is discharged. The secondary divisions of the ducts gradually unite to form an excretory canal for each of the two glands, which invariably pour the salivary secretion into the mouth in the vicinity of the tongue. When very small, as in Testacella, Onchidium, and Haliotis, they are found to be merely arborescent tufts placed on each side of the oral mass. Inall the Pectinibranchiate order, where the mouth is converted into a protrusible proboscis, the glands themselves (fig. 182, i) are found within the visceral cavity, and their ducts (e, e) are very long and tortuous so as to follow the movements of the proboscis in which they are lodged, running in contact with the esophagus to open at the extremity of that tube on each side of the spiny tongue; it is even probable that the secretion which they furnish at that point may assist, in some mea- sure, in the destruction of the shells and other hard bodies, which are submitted to the con- tinued action of this organ. In Doris and Pleurobranchus a glandular structure of considerable size is found near the commencement of the esophagus, which is of a brownish colour and plentifully furnished with bloodvessels. This has been looked upon as an auxiliary salivary organ, but as its duct has not been as yet satisfactorily traced, its real nature is unknown: but in Janthina there are distinctly four salivary glands, each furnishing a distinct duct; two of these run, as in Bucci- num, to the extremity of the proboscis, whilst the other pair empties the secretion of the corresponding glands into the commencement of the esophagus. Biliary system.—The liver throughout the whole class is of great comparative size, en- veloping the convolutions of the intestines and filling a large portion of the visceral cavity. That of the Snail consists of four large lobes (fig. 190, h.), each divisible into lobules, and these again into secreting granules, from each of which issues an excretory duct. The ducts gradually unite into larger trunks, so that the whole organ, when unfolded, accurately repre- sents a bunch of grapes, the stem of which would be the common biliary duct. In the same ani- mal the excretory ducts from each of the divisions of the liver unite into one canal, which opens into the pyloric extremity of the stomach (g) in such a manner that as much bile must be poured into the stomach itself as into the com- mencement of the intestine. In the Slug the liver consists of five lobes, and from these are derived two distinct biliary canals, which open separately into the intestine, one on each side GASTEROPODA. of the pylorus. A similar disposition occurs in Vaginulus (fig. 189, |, l’ ). In Scyllea the liver (fig. 187, d) is divided into six small and detached round masses, the excretory ducts of which open above the point where the esophagus joins the singularly armed gizzard (c). The liver of Aplysia is very large and forms three principal masses, among which are seen the convolutions of the intestine. The biliary canals are very wide and open into the third stomach near the aperture communicating with the rudimentary pancreas (fig. 188, e). In Testacella Haliotoidea there are two livers perfectly distinct from each other, and from each arises a proper duct, which opens sepa- rately into the commencement of the intestine near its origin. Onchidium furnishes us with a still more curious arrangement, being pro- vided with three distinct livers, pouring their secretions by separate canals into different parts of the alimentary tube. Each portion perfectly resembles the others in external appearance, and in structure as well as in the nature of their respective secretions, The exeretory canal which proceeds from the largest mass enters the esophagus, discharging itself near to its cardiac termination; the duct of the second terminates near the same point, whilst the bile produced by the third is poured into the gizzard itself. The insertion of the two former above the gizzard would seem intended for the same pu as the abundant secretion which is poured into the ventriculus succenturiatus of Birds, namely, to moisten the food before its in- troduction into the gi 3 it is, however, sin- gular to find the biliary fluid employed for this pe ; nor is the insertion of the third duct ito the first of the three stomachs of this animal less extraordinary, a similar arrangement occur- 389 ring only in a few fishes, as in the Diodon Mola The liver of Doris is very large, and not only is the bile which it secretes discharged by large and numerous ducts into the stomach, so wide, indeed, that it is difficult to conceive how the food is prevented from entering them, but moreover the liver furnishes a second duct of large calibre, which opens externally in the vicinity of the anus. A part of the bile in this case is evidently excrementitious, as there is no doubt that the second canal takes its origin from the substance of the liver. “ This,” says Cuvier speaking upon this subject, “is the first instance of the kind which I have met with, and the fact was sufficiently singular to make me hesitate long and examine the matter with all possible precaution before admitting it. It is only by one supposition that it can be explained otherwise,—namely, that the lobes of two different glands are so interwoven that they are not to be distinguished from each other, one portion producing bile used in the process of digestion, and the other secreting a fluid which escapes by the canal in question.” Before its termination externally, the secondary duct communicates by a short canal with a lateral receptacle, which forms a kind of gall- bladder, having its lining membrane much corrugated and its walls apparently muscular ; this is probably a reservoir for the excremen- titious fluid, in which it may be retained until the animal feels its discharge necessary. There is reason to suspect that the fluid thus furnished is a colouring matter, used as a means of de- fence, and expelled like the ink of the cuttle-fish on the approach of danger, but the matter is undecided. The bile is in all cases produced from arte- rial blood, and the liver is provided with but one system of veins’ answering to the hepatic. Organs of respiration —The respiratory or- gans of the Gasteropoda are found to be con- structed —— very various principles, adapted to the medium which they inhabit, or the pecu- liar exigencies of the individuals composing each order. Nevertheless in different groups allied by the generalities of their organization, the respiratory system is, in most instances, found to be constructed upon the same plan, and this circumstance more than any other has rendered the position and nature of the respira- tory organs the most eligible basis of classifica- tion. On looking over the table which we have given at the commencement of this ar- ticle, the reader will perceive at once that the names by which the different orders are desig- nated indicate the general disposition of the pulmonary or branchial appendages, and we shall therefore follow the arrangement there adopted in considering more minutely the pe- culiarities belonging to each. The first or Sigeruaresiien order is distin- ished by having the breathing a’ tus per- fectly po tothe influence of ae amreedds ing medium, which in all the genera belonging to this division is the water of the ocean; the branchie constantly assume the shape of arbo~ rescent tufts, placed in different situations upon the dorsal aspect of the animal. In Doris toot 390 article CincuLation, Jig. 321, vol. i. p. 649,) they form a circle around the anus. In Trito- nia they are disposed in two rows along the sides of the animal, extending from one extre- mity of the body to the other. In Scyllea they consist of little tufts irregularly disseminated over the surface of the back and upon the fleshy alz projecting therefrom. In Glaucus they form on each side three large and palmated fins, being used as agents of progression as well as instruments for the purification of the blood. In Qolis the branchie assume the shape of long riband-like lamelle disposed in imbricated rows; but whatever their form their structure is essentially the same, each tuft or lamella containing the ramifications of the branchial vessels, and effecting the oxygenisation of the blood by the extent of surface which they ex- pose to the action of the surrounding water. In the Infero-branchiata the respiratory tufts or plates are arranged around the circumference of the body, lodged in a deep groove between the margin of the foot and the edge of the man- tle which covers the back. The Tectibran- chiata have the branchie covered by a litle fold or operculum formed by a duplicature of the skin, and generally containing a horny or calcareous plate ; beneath this are seen the re- spiratory leaflets arranged in rows upon the two sides ofa semi-crescentic membrane : their structure in Aplysia is represented in fig. 191. Each branchial lamella (a, a) divides dichoto- mously into smaller plates until the divisions become extremely minute; the ramifications of the arteries and veins within them being dis- tributed to each are spread over an extent of surface adequate to the efficient aeration of the circulating fluid which they contain. The principal trunk of the branchial artery (c) runs along the concave margin of the crescentic membrane, while the large*venous trunk occu- pies the opposite or convex border; the veins from the branchiz all terminate in this great vein, their orifices being disposed in circles, as seen at d. The Pectinibranchiate order includes that large family of aquatic Gasteropods which are enclosed in shells, and the arrangement of the whole of their breathing apparatus is adapted to the respiration of water. The branchie re- semble in structure those of fishes, and are pec- tinated or composed of parallel lamin disposed like the beards of a feather, and attached in two or three rows to the roof of a large cavity placed under the integuments of the back ; or else in some rare cases, as in the Valvata cristata, the branchia is single, resembling a pen, and floats externally.* A very material difference is ob- servable between the truly aquatic species and the pulmonary Gasteropods which inhabit the water, but breathe air; in the latter, which are compelled to come to the surface to respire, the aperture leading into the pulmonary cavity is small and furnished with a powerful sphincter, so that the air taken in is retained at the plea- * For a figure of the branchial chamber of the Buccinum undatum, and an account of the ciliary movements which have been observed in many orders of Gasteropoda to be connected with respi- ration, the reader is referred to the article CILIA, GASTEROPODA. sure of the animal; but in those which are pro- vided with pectinated branchie, the entrance to the branchial chamber is a wide fissure, always allowing free ingress and egress to the circum- ambient fluid. Many genera of this order are provided with a special apparatus called the sy- phon, for conveying the water freely into the re- spiratory chamber ; this is a semi-canal formed by a fold of the right side of the mantle, and lodged in a groove projecting from the mouth of the shell; through this channel the water at all times has free admission to the gills. The respiratory organs of the Scutibranchiata re- semble those of the last order, and are contained in a similar cavity, to which the water is con- stantly admitted; but in the Cyclobranchiata the branchie consist of a series of lamellae placed external to the body, around the border of the mantle, by the edge of which they are overlapped. Respiration is effected in the Pulmonary Gasteropoda, whether they be terrestrial or aquatic, by an apparatus fitted for breathing the air of the atmosphere ; the lung or pulmo-bran- chia, as we may call this singular organ, con- sists of a large cavity placed beneath the man- tle, over the surface of which the vessels return- ing the blood from the system spread in beau- tiful ramifications, and from these the pulmo- nary veins take their origin, collecting the blood which has been exposed to the action of the air, and conveying it to the heart. A large orifice admits the air freely into this chamber, the walls of which alternately contracting, draw in and expel it at regular intervals by an action precisely similar to that of the human dia- phragm. In the Slugs (Limax) the cavity is small, but the network of the vessels spreads over its whole surface. In the Snail (Helix), on the contrary, the organ is much larger, but its floor only is covered with the respiratory ramifications. In fig. 322, of the article Crr- CULATION, vol. i. p. 649, a diagram is given of this structure, and in fig.190, (m, n,) 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 operculata, 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 branchiw, 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 ’ : 5 ; GASTEROPODA. 391 Fig. 190. 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, 0, 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 laws 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 branchie ; and from the t diversity of arrangement which we have ound 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 nea pe of the variable position of the heart, and as illustrations of the usual distribu- tion of the bloodvessels, viz. the Snail, (vide Circutation, fiy. 322, and the Doris, fig. $21,) 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- ES fei: eat gut ss 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- sipanee of the position of the branchie around the anus, removed quite to the posterior extre- mity of the body. e 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 (6, 6), 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 orgaus of generation, the foot, and the mouth; whilst the other large trunk is entirely distributed to the liver. In Tritonia the heart is placed near the centre of the body, and the auricle itself resem- bles a cylindrical vessel placed transversely 392 across the other viscera, and communicatin with the ventricle near its middle. The bloo arrives at the heart through four vessels from the long fringe of branchie, two coming from the anterior and two from the posterior parts. We have already described the disposition of the branchiz 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 large venous trunks to the vena cava or pulmonary artery (fig. 191, 6); 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 manner the blood GASTEROPODA. 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 vene cave 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 h’), 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 i, 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, Fissurella, 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 nae form of the heterogangliate, or as it has een less happily 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 aregularity in the appropriation of the nerves proceeding from them to parti- cular organs, which leave us little room for ‘ GASTEROPODA. hesitation upon this point; before, however, pened upon a more detailed account, we __-will offer a few general observations upon this system, applicable to the whole class. The __-hervous centres are obviously of a different ature from the cords by means of which they are connected into one system, and from the herves 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 Stagnalis, and has also been remarked in many of the conchi- ferous Mollusca. A secon uliarity 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 ay 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 csophagus 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 ran 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 cwsophagus 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 csophagus; 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 csophagus, the _ muscles of the mouth, and the salivary glands. Ata yee rae distance from these, and ' near terior ion of the bod ag vicinity of the pbc ap otok scans and the respiratory apparatus, is a fifth gan- glion communicating with the second and third by means of two long nerves, and givi branches to the liver, the alimentary canal, _the female generative system, as also to the branchiz 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 ich being distributed to very different struc- tures; but yet, speaking generally, there ap- VOL, 1. 393 = to be some reason for classifying their unctions. 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 eapraged 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 esophagus, and a large sub-csophageal gan- glion connected with it by two cords embracing the esophageal 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. ere is, however, placed under the esophagus 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 esophagus 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 ceso- 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 esophagus, 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 wsophagus, the nervous collar being completed by a simple 2D 394 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 esophagus 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 calectated 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 GASTEROPODA. 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. “ T 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 Planorbis we find two, in the generality of cases four; in a few, as some spe- cies of Golis, 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 (fig. 193) each tentacle is a thick and fleshy stem, near the extremity of which a smaller one isappended. 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 Scyllea 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 fig. 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 ofa — glove; it is in fact, when not in use, drawn with- . in itself by an extremely simple arrangement, GASTEROPODA. —" Structure of the tentacles 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 indicates the origins of the retractor _ muscles of the foot from the columella; 6, the ‘right superior tentacle fully protruded ; c, the I eee tentacle partially retracted ; d, the left inferior tentacle extended, and e, the right inferior tentacle fully retracted and concealed | within the hody; 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 lube ; 4, the nerve of the opposite side thrown into folds ; i, the retractor muscle of the same tentacle contracted ; A, the aperture throu ich the nerve and retractor muscle enter ¢ ; Ll, the brain; “4 Vision —The eyes of Gasteropoda are ex- mely small in comparison with the bulk of the animals, and seem more to re nt the rudiments of an organ of sight to be dapted to distinct vision. In many species | indeed they appear to be absolutely wanting. _ When found, they resemble minute black points, 395 by far too small 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 fe 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 pec 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 2pn2 396 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 fe. 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 fig. 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 Scutibranchiate 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- GASTEROPODA. tive apparatus is common to the Nudibran- chiate, Inferobranchiate, 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 tht 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 fig. 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 (¢), 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 ate, fig. 194. The male organs consist of a testicle, vas deferens, and penis. The testicle (s, fig. 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 (uv) 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 visceral 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. 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 (fig. 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, The penis (fig. 194, m) is a most sin-- when that organ 1s protruded, is sufficient! distinct, admittin cin facility an ordi » bristle (fig.194, 1). 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 would seem sufficient in them- Selves to fulfil the functions belonging to the en of both sexes, nevertheless we find 0 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, 2, fig. 194, 0) 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- nents. The multifid vesicles (fig. 190, x, fig. 194, ¢) are much less constantly met with, and are in fact almost peculiar to the snail; they are two groups of ceca, 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 pal the orifice paring to the bladder into passage by which the ova are expelled. The fluid farnished by these curious Sioulalar appendages is white and milky, but as this Secretion 1s almost peculiar to the genus Helix, its use is extremely problematic. The sac of 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 hin it will be protruded externally. This if broken off from its place of attachment, is speci renewed. To copie our description of the parts ‘composing this complex organisation, it remains only to mention the common generative cavity eee ae LC GASTEROPODA. 397 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 ly 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- poses approach each other, they begin their landishments by rubbing the surfaces of their bodies together, touching successively every pen This preliminary testimony of affection asts 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 mancuyres 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 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- GASTEROPODA. ening point of the weapon bared against him. At last he receives the love-inspiring wound, and the preliminaries thus completed, each repares for the completion of their embraces. he 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 be an 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 (fig. 189) a similar arrange- ment of the gens ir organs is observable, although some moditications are met with which deserve our notice. No sac of the dart is found in this animal, but a fasciculus of ceca, analogous to the multifid vesicles as far as their structure is concerned, is connected, not with the female apparatus, as in the snail, but 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 (p), from which it issues, much increased in size, to expand into a large membranous re- ceptacle (q), corresponding in function with the tortuous matrix of the Helices; this part of the oviduct is filled with an albuminous fluid, and from it runs the narrower canal (r), which may be regarded as the vagina, and which before its termination communicates with a lateral pouch, identical with what has been called the bladder. The testicle (p) ap- pears to consist of two portions, from which arises the vas deferens (0). On tracing this tube it is seen to divide into two branches, one opening into the bladder (s), an arrangement to which we shall again have occasion to revert, whilst the other runs forward to the root of the penis (w). The latter organ presents two por- tions, a long tubular cecum (v), 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 multifid 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 xe of the system. This will be seen in 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 (A). In Aplysia the organ of excitement is found joridium Meckelii (fig. 196); the - >" GASTEROPODA. near the right tentacle, where it protrudes, as in the Snail, for the purpose of copulation, Se Pa 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. Gencrative organs of Aplysia. 399 portions of this system removed from the body, and displayed so as to expose the internal structure of the parts composing it. The ovary (h) 1s 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 (f,g), called by Cuvier the testis, and sup by him to be solid and homogeneous 1n its texture, is found, when opens to be divided by spiral septa, resem- bling the scala cochlee 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 (0) communicate with the common e. In Onchidium, an aquatic species belonging to the inoperculate pulmonary order, the male and female parts are in a similar manner og at opposite extremities of the body, ut the former assume a more complicated structure than in the Tectibranchiata, which we have described. The ovary (fig.198, a, a, a) Fig. 198. mwew Fig A 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 (4), 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 (d), to the external orifice (h). The bladder (f) receives a large duct (¢) from the mass here assumed to be the testis, and _ gives off another of equal size, which joms the oviduct (d) prior to its termination. This 400 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 7 is much wider and of extraordinary length; its com- mencement (i) 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 fig. B, 198, the muscular cavity (m) has been laid open, and the mode in which the above tubes enter it has been displayed ; the smaller one (7) ends in a little horny papilla (g) seen in the engraving; the larger tube (2) 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 (0), 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 (m) is everted, the papille (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 a 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 organ 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 GASTEROPODA. 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 urina fluid, we are not aware of any chemical proo 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 conyerts 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- . Male organs of Buccinum. | able by the enormous penis attached to the right side of the neck (fig. 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 ap t object. n 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 its conyolutions a kind of epididymis (fig. 199, 6), and then increasing in diameter enters the root of the penis, through which it cago by a tortuous course (d) to the tuberele at extremity of this organ, where it opens externally. The penis when opened, as re- presented in the engraving, is seen to contain strong transverse iculi of muscle, which probably cause the erection of this organ ; they will at the same time vega it, so as to destroy in a great measure the zig-zag turns into Thich the yas 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 Murex the penis of the male is pro- _ portionally smaller; and, instead of a com- — vas deferens, penetrating to its extremity, } 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. Inthe Pulmonalia operculata the organs of both sexes are in every respect similar to those of the Pectinibranchiate order. In Paludina lone ( Helix vivipara, Lin.) the penis is retrac- GASTEROPODA, 401 tile, 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- lusea 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 marini. In Helix and Bulimus the eggs are naked and protected by a hard shell, whilst in Buecinum, 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 extraordin 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 theanimal, 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 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. hen 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 GASTEROPODA. 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- ared, 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 nage them- selves. Ina 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. bid a 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- _ run transversely, arising ap e GASTEROPODA. 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 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, fa 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- nded and semi-turbinated shell by a single See 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 ee they will, by producing a vacuum ath, convert the whole apparatus into a sucker, the adhesive power of which will be proportioned to the extent of its surface. sete foot of the corres is their incipal agent of progression. It is generall va fleshy dise, of vaitable 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. Inthe Slug, when opened from the back, the superior layer of fibres is found to ntly 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 403 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 dis : 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 Scyllea, we find it only adapted for grasping the thin stems of fuci and other submarine } yen ee for that purpose com- pressed an ved inferiorly into a deep sul- cus. In the Tornatella fasciata, Lam. the struc- ture of the foot is remarkable: beaten incessant] 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 dise 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 Cyclostoma 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 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 assistaut 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- cad is 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 areole 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 species 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 GELATIN. a eee pies secretion capable of emitting a light of considerable brilliancy. The luminous organ is a small dise 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 Nature seu Historia Insectorum, fol. 1737. Cuvier, G. Legons d’Anatomie Comparée, 8vo. 1799. bid. Mémoires pour servir 4 l’Histoire et l’Anatomie des Mollusques, 4to. 1817. De Blainwille, de \’Orga- nization des Animaux, ou Principes d’Anatomie Comparée, 8vo. 1822. Delle Chiaje, Mémorie sulla storia e notomia degli animali senza yertebre del Regno di Napoli, Ferussac, Histoire des Mollus- ques terrestres et fluviatiles, fol. lanzani, Opuscoli di Fisica animale e vegetabile, 1776, Reaumur, De la foemation et de l’accroisse- ment des coquilles des animaux tant terrestres qu’aquatiques, in the Mémoires de l’Acad. des Sciences, 1709. He continued the subject in the same work for 1716, under the title of Eclaircisse- mens des quelques difficultés sur la formation et Vaccroissement des coquilles. Hatchett, on the chemical Composition of Shells, Phil. Trans. 1799- Beaudant, Mémoire sur la structure des parties solides des Mollusques, Annales du Museum, tom. xvi. p, 66. Weiss, M. Sur la progression des Gasteropodes Terrestres, Journ. de Physique de Rozier, An. i, p. 410. Lamarck, Systéme des Ani- maux sans Vertébres, 7 vol. 8vo. 1815-1822. Har- derus, Examen Anatomicum cochlez terrestris do- miporte, Basile, 1679. (T. Rymer 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 jelly; 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 pureand 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 ee ee eee GELATIN. 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 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 rd TO of gelatinising, and becomes so far vrodified as oleate a rowiish 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 gees, and which, like dry gelatin, softens, but 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 eaters and free muriatie 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, 405 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 dilu' 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 properties of which closely resemble the carbazotates. 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 eaakst, By concen- trated nitric acid gelatin is converted into malic and oxalic acids, a fatty substance, and artificial tan.f 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 alumine 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 * Annales de Chim. et Phys. xiii. + Hatchett, Phil, Trans. 1800, p. 369, t Ibid. § Berzelius. 406 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 AtpuMEN.) 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, ORGANS OF GENERATION. 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 :— Atoms. Equiv. Theory, Experiment. Nitrogen . 1 14 16.09 16.998 Carbon 7 42 48.28 47.881 Hydrogen. 7 7 8.04 7.914 Oxygen 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 eorrespond. (W. T. Brande.) 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. 2nd. Gemmiparous, in which the young Sprout as it were from the substance of the t. 8rd. Oviparous, producing their offspring ova or germs developed in special organs ted to their formation. these modes of reproduction the two first are confined to the lowest or acrite division of the animal kingdom, whilst the third or ovipa- rous type is common to all other classes. Fissiparous generation is the — 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 fhnetions 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 transparent 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 go apt 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- glee the fissiparous mode of generation exhi- bits modifications which are extremely curious. In the beautiful Vorticelle, 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 sah 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 cove of its pedicle, is seen to be fur- ni with cilia at the opposite extremity to that on which they were previously found, while from the other end, ee ort the mouth, a new foot-stalk becomes gradually developed, and the creature assumes the shape proper to its species. Tf one of the bells remain Sacked to the pedi- cle, it continues to perform the same movements as the separation of the new animalcule ; but if both become detached, the foot-stalk perishes. In the strangely compound symmetrical bo- _ dies of Goniwn a provision for separation ; ars to be made in the detached portions of 407 which each perfect animal is apparently com- posed. The body of Fe Po i con- sists of sixteen minute trans t globes of unequal size, arranged in the same plane. This beautiful animalcule is propagated by @ 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 pet peo numerous progeny. The young animalcule is a minute, flat, Sshauien 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 ea, or buds, which at certain periods sprout rom 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 1s met with through a wider range of the animal roe than the last, = waciey Sonnet orms in many species of Polygastric Infusoria, and of Polyps, as well as in een the Cys- ag) Entozoa, and probably in some Acale- e. It is in the Cystoid Entozoa that we find it in its simplest form. In the Cysticercus and like- wise in the Ceenurus, 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 ysticerci 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 so ea perfect animals. Many of the Polygastrica are multiplied by a similar process, of which the Volvoxr 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 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 yolvox 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 gemmules 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, —ED.] ORGANS OF GENERATION. 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 lithophytous polypes resembles that of the Aydra, the young eing produced from buds or gemmules, which sprout from the living investment of their eal- careous skeleton. Such are the Fungie, in which the young are at first pedunculated, and fixed to the lamine 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 1s 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- tcitious 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 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 Actiniz 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 escribe generative canals ~ : : ORGANS OF GENERATION. fature 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, Bi cursorily glancing over the ovigerous c of animals, that important modifications of structure in the generative system render further classification necessary. In the lower forms, ovigerous s only have been dis- : covered, in which the ova are secreted, and ‘when matured, escape from the body, fit in _ every res for the production of a new animal. In other instances, in addition M. a + saad immediately appropriated to the de- opement of the ova, = fad 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 _ 18 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- uals, 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 auiating in distinct indivdwals, awe First Drviston.— 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 f the generative system in such species remains 1a matter of uncertainty. In the Kolpoda ncullus the spawn consists of a loose mass bf ova, connected by delicate filaments, from type at it under Stal gg Gaede 409 coloured, open into the interior of the stomach. The young Medus@ 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 Rhizosto- matous species through the ramified canals of the no gd Tn the fleshy polypes (Actinie) 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 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 nt through the stomachal orifice is attested both by Dicquemare and Blainville.* The different forms of Echinodermata pre- sent a similar simple arrangement of the gene- rative apparatus. In the Asteriade 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.t The radiated type of structure is likewise manifest in the depcstinn of the generative organs of the Echinide: in these the ovaria are never single or simply bilobed, but are at least four in number, or, as 1s 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 correspondin; number of simple apertures, which are pla around the anal orifice when it is central, but otherwise are considerably removed from this int. Nothing analogous to a male apparatus as heen detected in the Echinida. e 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 Chiaje 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. + 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, 25 410 The Holothuride 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 coeca, 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- ste in the ovary itself, which occupies a arge 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 lamine 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; but notwithstanding his observations Carus contends { thatthe 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 lamine 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 wonld 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. + Goetting, gel. Anzeigen, 1806. t Introduet. to Comp. Anat. ORGANS OF GENERATION, charged through a simple duct, unprovided with any appendage which can be looked u 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 h 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. Seconp Diviston.—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- agate distinctly to prove the identity in unction 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 diecious 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 Tenioid 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 central 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 ines nats Be! 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 a 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. 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 Cirruoropa ; 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 at the period of their extrusion; and such, in the opinion of the authors above mentioned, is a part of its office. _ Turrp Diviston.—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 Gastero 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 eeeca, communicating with @ minute extensible penis, which is placed behind the oral sucker. Near the penis a ‘small orifice is seen, leading to the ovigerous “sage which have no ee yegenaee with impregnating a tus; and the copula- tion of two individoals is thus tadlasanaable toa reci fertilization of the ova. _ Those of the Annelida in which the gene- Tative 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 me spot, and almost deprived of locomotion, h individual may in itself be sufficient for reproduction. t on compar tages and Dorsibranchiate Anneli male apparatus is composed of several pairs of secreting bodies, arranged on ch side of the mesial plane, those of the me side communicating with each other by a common vas deferens. In the Leech the asa deferentia, which convey the secretion of lhe numerous testicular masses, terminate in long protractile tubular penis, and at a short tance behind this the opening which leads __ * Catalogue of the Physiological Series of Com- ral nex Ba contained in the Hunterian nm, vol, i. 411 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 vulve. 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 Farth-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 ‘ype 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, be which the male secretion is probably furnished. The most complicated forms of this species of hermaphrodism are met with in the Gas- teropod division of Mollusca, existing through- out the Nudibranchiate, Tectibranchiate, In- ferobranchiate, and Heteropod 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 (fig. 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- yerted and concealed within the body, but ca- ble of protrusion at the will of the animal. e female portion of this system is composed of one wey; provided with an ample and tortuous oviduct, which serves, indeed, as a kind of uterus or egg receptacle, wherein the 2E2 412 ova are retained until ripe for extrusion. Near the termination of this oviduct are placed several additional appendages, some of which are peperatly 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 eggs as they are expelled. (See Gasrrroropa.) 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 Lymneus 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. Fourtn Diviston.—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 ORGANS OF GENERATION. 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 est) 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 oyo-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 Thatozoa (Ceelelmintha), 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 ia, ei i, ie ORGANS OF GENERATION. 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 oo as Filaria, the young are produced ive, the ova being hatched in the oviduct, a sufficient proof of internal impregnation al +4 a accomplished. ‘as i , in every part of their struc- ture, ae ter exciton froth | the Annelida to the articulated classes properly socalled. They are divided by entomologists into two classes, the Iulide or Chilognatha, and the Scolopen- dride 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- pendre, on the contrary, respire by trachew, which permeate their viscera, as in the insect classes. In the generative system of these creatures a similar relationship is evident. In Tulus, the generative system occupies the ante- rior segments of the body, the sexual apertures being found upon the rings near the cephalie extremity, whiletin 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 Ision. n the Scolopendra the generative organs are more easily distinguishable, and much resem- ble those of insects; they are, however, exceed- ingly curious. In fig. 201 we have represented the male s of the Scolopendra morsi- tans. The testes (a, a, a) are seven in number, and closely ed in parallel lines; each testis is com of two parts, precisely similar to each other, which are seen separate at 6; from each extremity of the fusiform testis arises a natrow duct, so that there are fourteen pairs of ducts arising from the fourteen secreting organs. Fach 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 cacum of considerable length. ___ The ovarian system of the female Scolopen- dra is a single tube, apparently without secon- dary ramifications. Als Male generative organs of the Scolopendra morsitans, 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 vesicule 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. Miiller, 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 terricola. 3. Spiral tubes rolled up into little balls, as in Carabus auratus, Aptinus displosor, Dytiscus, &e. 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; Scarabeus nasicornis, (Swammerdam.) 6. Simple tubes, divided as the last, but each division ending in a vesicle, as in Trichius fasciatus. 7. Simple tubes ending in stellated capsules, the apices of which are produced into slender tubes; Nepa 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 calcarata, Diaperis violacea, Tenebrio obscurus, Uidemera carulea, &e. 10. Simple tubes, each terminated by a trans- verse capsule, resembling the anther of a flower, as in Apis, Bombyx, Scaris, Calvinia, &e. 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, Elater murinus, Blaps gigas, Telephorus fuscus. 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 bicaudata. 14. Simple tubes terminating in verticillate utricles, as in Clerus alveolarius. 15. Simple tubes, from which arise utricles arranged like the teeth of a comb, as in Hydrophilus piceus. 16. Simple tubes, terminated by a simple sac- culus ; Gyrinus natator. 17. Simple tubes, terminated by a bunch of vesicles. 18. Simple tubes, dividing into minute canals, forming a kind of cauda equina; Tvi- chodes apiarius. 19. Branched tubes, each branch being termi- nated by a vesicle, as in Staphilinus masxillosus. ( 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 iN 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 7esticle of Staphy- branches, tubes, or agglome- linus mavillosus. rated vesicles. Testicle of Silpha obscura. Appended to the excretory ducts of the testi- cular organs, near their termination, is found a group of cacal tubes, evidently destined to provide an accessory secretion; these have been named from analogy vesicule seminales. They ORGANS OF GENERATION. 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- optera 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. Insome insects these tubes ies tenind 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 vesicule 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 pois of insects is a hollow tube, capable of ing 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 Chermis pyrus, however, the end is enlarged; in the common wasp it is spoon-shaped; in Crabro bilobed, and in some Vespe curved and bifid at its extremity. In Musca vivipara its apex is covered with spines; in J'yrophaga putris and some other Muscide 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 (Muscide) 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. n 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 prehensores, 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 prehen- Sores, an additional pair of forceps is placed 405 under the second abdominal segment. The prehensores are generally two in number; but in many Lepidoptera, Conopis and Libellula, three are mate around the anus. In Culex there are two pairs. In Locusta morbillose 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 ceca, 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 qgoed pe 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 viridissima there are thirty, and. in the hive-bee not fewer than a hundred and fifty ceca 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 ( Termes 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 Bre 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 Insecta.) The oviductus or excretory canal common to the ovarian tubes of the corresponding side of the body, sometimes opens into the cloaca, 416 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 ceca, namely, the spermotheca and the accessory glands. The spermotheca is a membranous saccu- 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 ; aud 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. Haighton, who refers the act of impregnation rather to some pene- trating effluvium or aura seminalis, which the seminal liquor may emit during a long period, than to actual contact between the semen and the ova. The auxiliary glands (glandule succentu- riate ), which are appended to the oviduet of insects, perform an oflice 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 whieh they are not unfrequently extruded. The structure of these secerning ceca 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 ceca give off secondary branches. 3. In others, as in Hippobosca, they are ramified tubes terminated by blind canals. 4. In Elater Murinus 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 ceca. 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 ORGANS OF GENERATION. 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 Insecra. 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 acapacious matrix, in which at certain seasons the larve are contained either agglomerated in masses, or arranged parallel with each other in flat bands. In his state each larva is invested in a delicate membra- nous bag. It is remarkable that all these larve are carnivorous, their office being to remove putrifying flesh; hence the necessity of their ing produced in such a state as immediately to commence the work 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 youn 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 su 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 pennata, Miill. ¢ Monocites pulex, L.) ave equally ca- pable of producing fertile females through several successive generations; nevertheless ORGANS OF GENERATION, 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 ae of the last generation less so than the rst. Arachnida— Tn 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 fora detailed account of its structure and presumed functions the reader is referred to the article ARACHNIDA, The female organs of the Araneide are equally devoid off totaplitation: The ovaries are simple membranous bags, which occupy when distended a considerable portion of the abdomen, and are found to contain ova ag- aug together in considerable numbers. rom 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 | , the secretion of which is dis- charged externally by a double penis resemblin that of some reptiles, which is protrud through a valvular aperture seen upon the ventral surface of the thorax. The female organs of the Scorpion, like those of the male, are com 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 developement of the embryo may be easily distinguished through the 417 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.* rustacea.—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 tegion of the thorax; in both cases these organs appear at first sight to be of a dense landular structure, but, on examination, are d 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 coxal portion of the fifih 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- oe eggs as they successively esca rom 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 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, com 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 p yer aE a 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 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 coca, in- closed in a membranous capsule, into which ay 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. Vertebrata Ovipara.—tn 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 ORGANS OF GENERATION. 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 1s 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 ( Clupea 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 cecal tubes are prolonged to the sur- face of the organ, where they terminate by rounded extremities, giving the whole viscus, oon 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 Blennius 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 radi- 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- sated, 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. Structure of the Testes in Clupea Alosa. this arrangement we have, therefore, the simplest form of the isolated ovaria of Reptiles, Birds, and Mammalia, in all 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 afier 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 be its termination the walls suddenly increase in thickness, developing in their interior a large gland destined to furnish the horny coverin ich invests the eggs of these creatures. ond 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 419 in regular lamine, 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, ismuch in- ferior, and the whole organ 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 lamella 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- ments that when 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 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. SS Generative organs of Male Frog. a, Cloaca; 6, opening of genito-urinary canal ; ce, opening of bladder into cloaca; d, rectum; e, bladder ; f, testes, that of the right side in situ; g, kidneys; h, seminiferous tubes; ¥, tube serving both as ureter and vas deferens ; k, vesicule seminales; 1, fatty appendages to the kidney. In other Amphibia the organization of the testis is essentially the same, but the seminal coca, 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- ORGANS OF GENERATION. 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 (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. 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. ay 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 su 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. which unite intimately along the u aspect of the organ, but leave inferiorly a bey sane 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 merated, to the form which they present in irds. Each ovaty assumes a racemose aj pearance, and consists of a number of ova in various states of perfection, which are loosely attached to the sides of the vertebral eolumn by folds of peritoneum. Their structure, however, is essentially that which has been already de- scribed, and the ova, when matured between the vascular lamine 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- eareous covering produced from the thicker portion of the oviferous tube, The females of the Chelonia 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 vertebrata, 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. is 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 param 8 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 smovuth and vascular in its upper portion, where the yolk receives its albuminous covering, but becoming villous and plicated where it secretes the shell. 421 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 Miiller as not ge than the 0°00528 of a Parisian inch. ese 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- tens, 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 eae which hitherto we have found to dis- charge themselves by one common orifice com- municating with a cloacal ile 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 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 ey facilitates its ejection. e shall proceed to speak of these cireum- 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 Glires, 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 oin through the inguinal canal, and not un- equently are contained in a scrotal pouch formed by the integument behind the pubic arch ; oat 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. ORGANS OF GENERATION. 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. Cowper's 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, not 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 (Phascolomys ), 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 Cowper's 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 Europeus) 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. powerful muscular sheath, calculated to en- sure the expulsion of the fluid which they elaborate. * The most remarkable arrangement of Cow- per’s glands is seen in the Ichneumon ( Her- pestes Ichneumon, I\liger): in this animal they are very large and occupy their usual position, being invested with a 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 into a cul-de-sac common to them and e canal of the urethra. Accessory vesicles. — These are auxiliary glands, which pour their secretions into the canal of the urethra. They appear, when resent, to take the place of the tate, ing 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 ceca, more or less ra- mified, and in the season of sexual excitement are filled with a fluid resembling that contained in the vesicule 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 ceca, arranged in ckets, the number of which varies much. us in 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 Dasyprocta 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 cecum 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 many the Muride 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. Fig. 208. 423 The annexed figure, (fig. 208,) ws. cooper i tin; the male generative viscera of the Rat ( Mus Rattus ) exhibits an example of the t 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 vesicule 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 caeca which compose it ; ¢, the middle prostatic ceca; d, the anterior prostatic ceca. 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 (f). 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 the inclosure 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 urethre. The corpus cavernosum, 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 lamelle, 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 animals the organ is ay PH by a bone developed in its interior: this arrangement exists in the Quadrumana, Cheiroptera, the Plantigrade and Digitigrade Carnivora (ex- cept the Hyzna), 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 seminal glands, the latter embedded in the erectile tissue of the corpus spongiosum. The muscular portion does not always join the vas- eular part ina 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 cul-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 iu tances, 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 a 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 Vivipara, properly so called, comprising the placental orders. The former division approximates in every particular to the oviparous type of structure; GENERATION. the oyaria 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 ina 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 Marsuprata. In the Placental division gestation is com- peat within the uterine cavity by the deve- opment 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, VESICULE SEMINALES. (T. Rymer Jones.) GENERATION (in Physiology) generatio; Fr. génération; 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- liar change becomes an independent individual entering upon a new life. Othe 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- dent existence. 37°, 58 (100 F.) same ei three times in the tem- perate zone, the external temperature varying from 12° to 17° (53° to 62° F.)J 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 intluence 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 37°, 11 (99° F.) 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 659 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 i 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 s ws 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 aletsoting 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. Gentil 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 halfa degree of his original heat in the mouth and 2x2 660 hands, and a degree anda 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 toa degree and a half R. Effects of external temperature upon an isolated part of the body—Under this head let us examine, ist, 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. Gentil. 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 out 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 163° R. (69° F.), and after the expiration of an hour and a half it was only 244°R. (87° F.). The foot, in the same cir- cumstances, 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 ina corresponding degree. Whence follows this axiom,—that we cannot either raise or lower the temperature of any one part of the body without all the other parts of the frame being affected, und suffering a corresponding rise or Jall 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 ANIMAL HEAT. 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 sane’. 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 ¢. (100° F.), Franklin observed that the tempera- ture of his own body was nearly 35°, 55 ¢. (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, have a 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. the interior being prevented from escaping by means of a circular 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 98°, 75 c. (122° to201° F.), 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- aed nearly equal at the moment of their leath. 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 tc end 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° ¢. e temperature of the er being increased to this extent becomes . Itis 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 iter, 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 es than the surrounding air. A fact of this kind could not remain ; en. and Barmy with others. Accord- ingly we observe among the experiments of Dr. Davy such facts the following :—The temperature of the atmosphere being 32° c. * F.), that of a tortoise was only 29°, 4 661 (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 4 toga 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, ese 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 treat of 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 or 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 fallinto 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. one corned 51 age con- uently, a) to have an ulty of pro- cast heat. Pot in the mere fact of their ain: 662 taining 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- por inferior to that of the air, and this y 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 heat.—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°, 5c. (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. ANIMAL HEAT. 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. 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 a parent when we compare the constitution in early youth and inadult 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 tip 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 that 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 various 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 actually exist, although an opinion to the contrary had always been entertamed 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 “yeeaae itself in a still more marked degree. f 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, &e. &c., and is probably, as among Mammalia, universal. Whence we may conclude that the 663 phenomenon is general as regards warm-blooded animals. We might have taken it for granted that man was compzised 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 twod 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 te than in adult age, in the second it is higher. The differences of sas pan 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 ition, it be removed from the mother and ept 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° ec. (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 fart er 1°, 25; in thirty-five 664 minutes more it fell 3°,12; in thirty minutes more 2°,50; in twenty-five minutes more 1°,25; in thirty minutes more 1°,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 highera 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- ingair. 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° ce. (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 resent 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 different genera and families; and this, in fact, is what actually happens. A young guinea-pig, 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 acondition to walk, to eat, and, as it ANIMAL HEAT. 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 ina 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 Ff ae 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 standard 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 eyes 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 determinemore 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 Vertebrata (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 organizatioa 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- - cooled down to 14° ANIMAL HEAT. 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 t. Thusa young rabbit two days old had m 23° ¢. (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 mes 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 cireum- 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° ¢. (72° F.). The same thing happens with swallows, sparrow-hawks, &c. Buchs Jaw 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 d but little below that of their parents. Birds, there- fore, form two groups as regards the production of tem , 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 that distinguish them are not the 665 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 ina 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 we wd to engender it, belonged to the coat. his 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, asthe kitten, the puppy, &e., 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 apring and summer. here 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 s0,—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- uently 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 ina 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 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 orgaus of their progeny. We have already observed that a defect 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 state 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 eperupras 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 teeth. 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 ANIMAL HEAT. 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 ee Pe Tera e ANIMAL HEAT. the ture of ten children born at the full time was 34°,75 c. (94°,5 F.); the tempera- ture in no case descending lower than 34° (94° F.), and ranging between this and 35°,5 ec. (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- yous functions. The celerity of the motions of circulation and ss seomtg 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 oer 3 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 ee by the celerity of the 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- 667 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 NEAT 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 there 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 hhoays 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. If, 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 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 0°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°,5c. 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 ccoled 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° ec. 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 casita 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 first 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 the: 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 ANIMAL HEAT. or po apparent difference in the external appear- auce 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 uantity 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, kc. 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. 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 s the body in the two opposite Seasons. ey 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, for 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.), differing at no time from it by more than a 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 once rtain 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. The 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 uction with a greater loss; in summer a 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 takes place 669 Se it is to be preeee 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- lication. If the Boulty of producing heat is ess 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 amidsta quantity of melt- ingice. Air thus cooled soon reaches the point ofextreme 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 es 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 contaned 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, oceupied 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 ¢., 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 bein, 12° and 3°,5c. It ought to have been stat that in the experiment in the winter month, the birds had been for some time kept ina 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- uently, with reference to the powers of pro- ke 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 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 @ 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 — are then also decidedly less vigorous. hat 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 ANIMAL HEAT. manifested, it is necessary there be presenta 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, one 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 ee ea er we Peay |e ee) ee eee a ae a, Se + i- ANIMAL HEAT. 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 t 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 many ob- servations of high interest upon the state of the circulation in hybernating animals. The writer also obse the same diversities in the temperature of these animals according to their state of sleep or watching; but he had not pentones his observations at the time Dr. Hall’s paper ap - 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 to the temperature of their body, which is high during the wakin period, low during that of sleep, the exte temperature having no part in the phenomena. The difference of temperature coincides very evidently with the state of the nervous system— its 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 671 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 temperature of body equal to thatof 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 —* to the state of watching in summer, ow 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 siedine of atmospheric temperature in autumn, they will exhibit a temperature of ray 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 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 ec. 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 ¢., 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 ower. Ifthey 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 suffer 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 conformity 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 J/ethargic. 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- erature 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 warin-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 ina state of lethargy. When ANIMAL HEAT. 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 unlergone 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 fora time and toa 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. 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 nérvous system that is acted upon primarily and cami by changes of external temperature. n the first place the impression is felt instan- taneously ; in the second place the intensity of the ‘sengation 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 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 o cold. blooded animals. eA 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 ifest, from the circulation of the venous prolonging life at every degree short of VOL, It. 673 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 te 2Yr 674 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 cireum- 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 Resprra- 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 he 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 ANIMAL HEAT. 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 n 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 resents differences. Warm-blooded animals aving 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 d 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. ——s— - ANIMAL HEAT. _ 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 the most marked manner the Vertebrata having a constant or all but a constant temperature, from the hyber- hating 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 tem re 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 perpomon 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- erease of temperature which tends to counter- balance the effects of the refrigeration. The com ion, however, is not perfect. For in 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 tems ; the second consists essentially in is last kind of excitement. The sharpness of the cold stimulates the cou. pies motions, which become accelerated, 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 as it remains within certain and suitable limits, is a reaction that maintains the eco- nomy in a state 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 675 whose system is energetic to resist the effects of rigorous cold, by | pervapry: 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 s tem is less than in the former. This is what occurs universally in very early life. Itisa 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 medicatriz nature is uliarly and most strikingly manifested. is 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 seen 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 in 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 ina 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 ide, 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- in other conditions and circumstances m analogous reasons. Exercise, according to its degree and the degree of temperature of the external air, is adequate not es to compensate a chill, and to restore the body to its pristine temperature in every part, but even to i more than this. If the exercise has been sufficiently prolonged, but not been excessive, it may be su ed ; and the body, now re- stored by its means to its temperature, will be . 2y2 676 apt to retain it longer than it had done 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 ecoriomy 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 Test, 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 eold acting at first without opposition on the part of the system, and then combated by belt and voluntary reaction. First, we ave coldness, paleness,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? Itis obvious from what precedes that the temperature of the body may be indiffe- ANIMAL HEAT. 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 ease 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, aud 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, &e.; 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 peers have not been too extensive, the skin eing 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. ceases after a certain interval of variable extent, according to various circumstances; and _ @ state of tranquillity comes on in which the nee recovered the faculty of engendering by the ordinary means the quantity of heat ne- 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 itisa _ 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 fits or paroxysms, he ends by so far fortifying himelf 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 states ? ith 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 cireumstances where there is but slight production of heat, the feeling of cold may induce acceleration in the respiratory and circu- latory motions. Now ithas 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 —— -— = 7 677 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. Ina 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. There 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 5 ear fatal without the intervention of art. This is that form of intermittent which is known at Rome especially under the name of the febbre algida, or cold fever. It often happens that the patient, 678 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 ish. 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 @ 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 ANIMAL HEAT. 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 Firther; 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 cireumstanced. 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. Villermé 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 thatthe mortality of infants from their birth to the age of three months was owe 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 constitution to meet this unwonted demand upon their calorific powers, experience an increase in the energy of the functions upon which the peters 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, inas 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. tions that have just been particularly mentioned, it is obvious, ait find dencives Tenefited b the change ; they are continually 5H wih larger ences of heat of which they were ially 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 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 or 4 feels the deteriorating influence of this additional excitement, which thensuperinduces a series of aptate rco cee of various degrees of intensity ing 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 a in the acute form, after recovery, 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 . 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 medicatrix nature, the ten- pees de 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 ual and insensible, the other is sudden 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 traly pathological, and the disease which results is continued fever with excessive heat of surface in 679 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. t us see if we can explain this fact with the assistauce 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- ns in the course of the second winter, these individuals begin to experience the 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 w hands will keep one plunged for some time 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. Ifit 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 feeli alone the hand seems hotter than the other; tri 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 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 jn 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. Itis 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 51°,25c. (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 41°,25 to 53°,75c. (106° to 129° 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 ANIMAL HEAT. Dr. Dobson’s experiments, a young man con- tinued for twenty minutes in a dry-air stove, the temperature of which was 98°,88 ¢. (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°,7 ec: (240° and 260° F.), In assigning 40° or 50° ¢. (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° ¢. (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 coois 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. 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 eflects of a given temperature upon the body. Refrigeration by simple contact increases in amount with the rate of motion of theair. 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 _veclag a cause of cooling a cold wind must 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. Sic 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 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 tothe 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 x 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 F.ng- land, France, &e. spring is a more dangerous season than autumn, ve are, however, cer- tain cases of sudden transition that are useful and salutary, as for instance,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- ane ag even of the most sudden kind, pro- ided 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 681 be regretted that recourse is not had to it more uently. Itis 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 skin is hot and dry, which is also the period of the highest excitation. The experiments upon the effects of baths, uoted above, tend also to show the propriety of e practice ; inciting 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 Eras 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- rature. Now this is precisely what is done y 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 ves much more lasting. As the cee who 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 joen= 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 isa diminution of tempe- rature, unless other causes oppose such an ef- fect. Bloodletting, it must be observed, is not the sole means of aging ome such a change in the constitution of the blood. We can 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 elements 682 —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 ease, to make up the quantity of circulating fluid ; and if this faculty have only fluids to work upon, it isevident 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 ar ve ge rtion of solid matters from the blood, which therefore, when excited, e 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 roduce 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 ie 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 ANIMAL HEAT, conjunction is indispensable te the success of any of the others. Of all these means, one only is the pte a effect of art, namely, the application of cold ; the others are processes of the same natura medicatrix, 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 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. CoNnFIRMATION 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. simple conditions. These conditions them- selves are, in the first place, assumed from comparisons of the organization of the two ae groups or series into which the animal ingdom is divided with reference to heat— the cold-blooded animals, and the warm- blooded animals. In this review we have avoided all h esis, 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 rei in this comprehensive whole, which em! 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 ;— T allude to the enquiries of lap ois, Sir Benjamin Brodie, and Dr. Chossat. 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 incipal condition, which we have assumed m 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- 683 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 heat, by demonstrating in a series of experiments the following very im- rtant fact, viz. that the depression ¥ animal Jet is constantly in relation with lesions of the nervous system, whether these lesions im- plicate the cerebro-spinal system, or the system the great hetic. Y We eomthcn 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 Resprration, to which we beg to refer. With to the opinions of writers generally, we 1 be content to observe here, that they have for the most part ed 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 en of the nervous system,—a conclusion to whi 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. Or 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 Dabing 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 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. Haller, 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. Braun, 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 inthe Svenska Vetensk. Akad. Hand- lingar for the years 1764 and 1766. Hunter, Ex- erts, on the power of producing Heat, and on the eat of Vegetables and Animals, Phil. Trans. 1775- 1778, andin Animal Economy. Crawford (D.J.M. ), 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. Righy, Essay on the Theory of the Prod. of Animal Heat, Lond. 1785. Delaroche et Berger, Memoire, &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, Mém. sur la chaleur animale, Ann. de Chimie, t.iv. arle, Influence of the nervous system in regulating Heat, Med. Chir, Trans, vol. vii. Chossat, Influence du Systéme Nerveux surla Chaleur Animale, Thése, Paris, 1820. Dulong, De la Chaleur Animale, Journ. de Physiol. t. 3. Despretz ( Rich. ), Exper. sur la Chaleur Anim, Ann. de Chimie, t. 26. Home, Influence of the Nerves in producing Animal Heat, Phil. Trans. v. 115. Collard de Martigny, De V Influence de la Cir- culation, &c, sur la Chalear du Sang, Journ. Com- plem, t. xliii. Vide also Journ, Complem, t. xxvi. HERMAPHRODITISM. The general work on Physiology, particularly those of Rudolphi and ‘Tfedemann. Czermack, On the Temperature of Reytiles, in Zeitschr. fiir Phy- sik, &c. Bd.3. Berthbld, Neue versuche uber die Temperature, &c, Gotting. 1835, Transl. in Ann. d’Anatomie, &c. Mai 1838. Newport, Temp. of Insects, Phil. Trans. 1837. Becquerel & Breschet, Mém. surla Chaleur Animale, in Ann, des Sciences, Nat. Seconde Série, t. 3, 4, & 9. (W. F. Edwards.) HERMAPHRODITISM, or Hermaruro- pism;* Hermaphrodisia; androgynisme, gynan- drisme ; hermaphroditisme, &c., of the French; ermaphrodismo of the Italians; 2witterbildung of the Germans, &e. 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 Ph 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- pee in persons actually of the male sex. e 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 Epng, Mercury, and Agpodirn, Venus,) and the nymph Salmacis. See Ovid's Me- tamorphoses, lib. iv. fab. 8. HERMAPHRODITISM. 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 tae 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 685 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 mal 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. In the Female ; (Spurious Hermaphroditism < { true ey Vertical or L 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 Tn the Male.. Transverse .. { From excessive development of the clitoris, &e. From prolapsus of the uterus, From adhesion of the penis to the scrotum. From extroversion of the urinary bladder. fon hypospadic fissure of the urethra, &e. side. Testis on the left, and ovary on the right side. Testis on the right, and ovary on the left rLateral...... ; External sexual organs female, internal male. External sexual organs male, internal female. vesiculz seminales, and rudiments of yasa deferentia. Testicles, vasa deferentia, and vesicule se- minales, with an imperfect female uterus and its appendages. Ovaries and testicles coexisting on one or both sides, &e. the diversified fornis 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. [we and an imperfect uterus with male I. SPURIOUS HERMAPHRODITISM. A. Inthe female.—There aretwo circumstances in the conformation of the genital organs of the female, the existence of each of which has oc- 686 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 growin an equal ratio with the other external genital parts, so that at puberty it is, as a general law, Bund 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 fcetal life. In some instances where this occurs, the. re- semblance of the external female fo the exter- nal male parts is oceasionally considerably in- creased by the apparent absence of the nymphe. Osiander* endeavoured to show that at the third or fourth month of feetal life the nymphe are very imperfect, and so very small as not to be easily observed. Meckel,+ 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 naturalcourse 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- phe, but the resemblance of the female to the male parts may be still further increased by the persistance of the original intimate connexion of the nymphe 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. e 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 /Etius 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 Mannel d’Anat. Gén, tom, iii. p. 666. HERMAPHRODITISM. modern observations of Niebuhr* and Son- nini,t 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 rpsBadss and eraspiorprcer, 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, (fricatrices, confricatrices,) and alluded to the depravity to which it led.f * Besch g von A s. 77. 2 he dans la Haute et Basse Egypte, tom. ii. ¢ Mart. Epigr. lib. i. ep. 91.5 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 Pan! 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 ep-y when speaking of the depravity of the women of his own age, remarks, ‘* non mutata foemina- rum natura, sed vita est... . Libidine vero, nec maribus quidem cedunt pati nate. Dii illas deeque male perdant, adeo perversum commente os impadeaite viros ineunt.” Op. Om. Geney. 1665, p- 787. Clemens Alexandrinus, in his Pedagogus, exposes the same vice: ‘* et contra naturam fremi- nz, viros agunt aaa rl et nubunt et etenim uxores ducunt.” Iso Ath » Deip ph 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 (androgyni ambigui serus) “ 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 Stuatsverfassung 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. Inthe essay last referred to, Tholuck incidentally mentions (p. 422,) that the deity Mi- tra (Mithras of the ancient Persians) was herma- hrodite. For our own part we are inclined to elieve 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 ate 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 T'almudists, 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, c. 24; and Arnaud’s Mémoire, 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 was androgynous both in form and aye, * ——s—- ro - MLERMAPHRODITISM. The dimensions which the clitoris occasion- ally presents are such as to render it, in t of size alone, not unlike the male penis. It is not seo he found of two or three inches in length, but sometimes it is seen five and six inches long. Dr. Clark frequently found the an inch long, and thick in proportion, among the Ibbo and Mandingo women.* ler+ and Arnaudt 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 o in the Mammalia naturally differ- ing from the male bes He 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 €arnivora and Rodentia, as in the lioness, cat, racoon, bear, marmot, &c. the clitoris coutains 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 (Loris gracilis or Stenops tardigra- dus), the clitoris is of a very large size; and the urethra, as first pointed out by Daubenton,§ name,” ( avBpoyuvy xas sie xa ovopea,) Probably from the licentious pu s alluded to by Justin Martyr, or from the weak and imbecile character of her- maphrodite individuals, the word came in latter times to signify effeminate and laxurious. The ancient lexicographer Hesychius gives it this meaning ; and Theodoret, in his Therap., speaks of Bacchus as being year effeminate, and an- drogynous—( yung wy, xa OnAvdpiag, xas avBpoyuvos. ) ome’s a . Seite iii. p. 317. On the peculiarities e ex genital organs in va- rious African tribes, see a learned paper by Prof. Miiller in his Archiv fuer Anatomie for 1834. Ht. iv. s. 319., with ample references to the observa- tions and opinions of Levaillant, Barrow, Peron, Lesner, Lichtenstein, Burchell, Somerville, &c. See also Otto, in his Neue Seltene Beobachtungen zur Anatomie, p. 135, shewing the very prominent external female parts of different African tribes to consist differently, 1, of enlarged aes, 2, of enlarged labia, and 3, of the enlay clitoris, t hh. Phys. tom. vii. part ii. p. 81, 82. ¢ Dissertation sur les, Hermaphrodites, p. 372. See also H g, De E ia Clitoridis nimia, Jena, 1671; Tronchin, De Clitoride, Lugd. 1736 ; and Ploucquet’s Literatura Medica, art. Clitoris Magna, tom. “ee 5 § Audibert, Histoire Nat. des Singes, tab, ii. 687 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 ny oe 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 perineum 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 oie 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 git rather masculine, the mammez slightly eveloped, 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 of an infant, that was christened and looked upon as a boy, until dissection after * Medical Gazette, xiii. p. 184, 688 death shewed that the sex was actually female. The uterus and other female organs (fig. 287, ¢ec) were present and apparently naturally Fig. 287. formed; but the clitoris (6) 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 (a), which was not the entrance of the urethra, but terminated in a cul-de-sac. Columbus* and De Graaf+ 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 { 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, nymphe, 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. ; + Op. Om. cap. iii, xv. or, De mulierum organis gen. insery. with a plate. ¢ Arnaud, 1. c. p. 309. § Jahrbiicher oe Staatsarzneikunde, (1809), 8. i HERMAPIIRODITISM. 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 ruge. 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 mamme 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 104 (?) inches (27 centimetres) in length when at rest, but somewhat more when erect; its glans was imperforate, and covered in three- fourths of its cireumference 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 yulva 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 Ja Faculté for 1815, p. 273. HERMAPHRODITISM. with some of the female genital organs deve- loped in so excessive a degree as to approach — points the more t structure of 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 com 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- ed organ similar to the normal type of struc- ture of the same organ, in some of the inferior animals. Armaud* 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, ¢) in the right groin, which 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 = angle. e glans (b) was well formed, 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, pl. x. 689 its posterior as it became distended when the patient sali 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 peranum. At each menstrual period a tumour (d) always appeared in the perineum, which gradually increased in size, becoming, in the course of three or four days, as large as a small hen'’s egg. When the perineal tumour had reached this size, blood began to flow from the anus, although no hemorrhoids 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 A seed at which the perineal tumourabove alluded to ecw 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 perineal 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 afierwards. 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 mamme 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 ighs and legs round, and the feet small. n 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- the tumours in the labia to be the ovaries escended 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 im fect urethral canal in the body of the clitoris. Spurious hermaphroditism from preternatural enlargement of the clitoris has been ised 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. Lecogt has detailed — * Rudolphi’s Bemerkungen auf einer Reise, &c. Bd. i. s, 79. See a case also figured by Raysch in his Thesaurus Anat. lib. viii. no. 53. + Journ, Prat. de Méd. Vét.-1827, p. 103, 22 690 the case of a calf which Gurlt* believes to belong to the present head. Neither testicles nor scrotum were observed externally, and the penis or enlarged clitoris, which occupied its normal situation, was apparently perforated by the urethra, and crooked upwards so as to throw the urine in that direction. Mery + shewed by dissection the true sex of a monkey, the length of whose clitoris had deceived some observers with regard to the true sex of the animal. The enlarged clitoris was furrowed on its inferior surface. The clitoris of the female Quadrumana is, as shall be afterwards more particularly mentioned, relatively larger than in the human subject, and retains in a greater degree the size and type of structure of this organ in the embryo. We may here further mention that, as pointed out by Blumenbach,{ the clitoris and orifice of the urethra are placed at some distance from the vagina and in front of it, in the rat, mouse, hamster, &c. This normal structure has some- times been mistaken for an hermaphroditic mal- formation.§ 2. From prolapsus of the uterus—It may at first appear strange that this occurrence should ever lead to any difficulty in ascertain- ing the sex of the individual, though not only non-professional observers but even the most intelligent medical men have occasionally been so far misled by the similarity of the protruded organ to the male penis, as to mistake a female for a male. Of this circumstance some curious illustrations are on record. M. Veay, physician at Toulouse, has inserted in the Philosophical Transactions of London, vol. xvi. p. 282, a brief account of the case of Marguerite Malause or Malaure, who was entered as a female patient in the Toulouse Hospital in 1686. Her trunk, face, &c. pre- sented the general configuration of a female, but in the situation of the vulva there was a body eight inches in length when on its fullest stretch, and resembling a perfectly formed male penis in all respects, except in not being pro- vided with a prepuce. Through the canal perforating this body she was alleged to eva- cuate her urine, and from its orifice M. Veay had himself an opportunity of seeing the men- strual fluid flow. After being examined by several physicians she was pronounced to be more male than female, and ordered by the civil authorities to exchange the name of Mar- guerite for that of Arnaud, and to wear male attire. In 1693 she visited Paris in her male habiliments, and reputed herself endowed with the powers of both sexes. The Parisian phy- sicians and surgeons who examined her seem all to have accorded in opinion with the faculty of Toulouse, until M. Saviard|| saw her and de- tected the supposed penis to be merely the prolapsed uterus. He reduced the protruded organ, and cured the patient. Upon the enigma * Lehrbuch der Pathol. Anat. Bd. ii. s. 193. + Hist. de l’Acad. mtg tom. i. p. 345, ¢ Comp. Anat. p. 335. grorbel, in Nov. Liter. Maris Balthici (1698), p- 238. |] Recueil d’Observations Chirurgicales, p. 150. HERMAPHRODITISM. of her hermaphroditism being thus solyed, she was permitted by the king, at her own request, to assume again her female name and dress. Sir E. Home* detected a case of reputed hermaphroditism of the same description as the last, in a French woman of twenty-five years of age, who exhibited herself in London, and pretended to have the powers of a male. The eervix uteri was uncommonly narrow, and pro- jected several inches beyond the external open- ing of the vagina. The everted mucous surface of the vagina had, from constant exposure, lost its natural appearance and resembled the ex- ternal skin of the penis. The orifice of the os tince had been mistaken for the orifice of the urethra. The prolapsus had been observed at an early age, and had increased as the woman grew up. Valentint mentions another analogous in- stance of sexual ambiguity produced by a peolapens of the uterus. In this case the usband mistook the displaced organ for the penis, and accused his wife of having “ cum sexu virili necquicquam commune.” A case quoted at great length by Arnaud f from Duval, of reputed hermaphroditism in a person that was brought up as a woman, and married at twenty-one years of age as a male, but who was shortly afterwards divorced and imprisoned, and ordered again by the Court of Rouen to assume the dress of a woman, appears to us to belong very probably to the present division of our subject, the reputed penis being described as placed within the vagina. The recorded details of the case, however, are not so precise as to leave us with- out doubt in regard to its real nature. In cases such as those now mentioned, in which the prolapsed uterus, or, more properly speaking, the prolapsed uterus and vagina have been mistaken for the penis, it appears proba- ble that the neck of the uterus must have been preternaturally long and narrow, otherwise it would be difficult to account for the apparent small diameter and great length of the prolapsed organ. Among Professor Thomson’s collection of anatomical drawings of diseased structures there is one of an uterus containing in its peed a fibro-calcareous tumour, and having a nec of three inches in length. M. Cruveilhier§ has represented a similarly diseased uterus with a neck of between five and six inches. An organ shaped in this manner, whether fiom congenital malformation or acquired disease, would, when prolapsed for some time, repre- sent, we conceive, a body resembling in form and size those observed in Saviard’s and Home’s cases. The prolapsus arising from a protrusion of an ordinary shaped uterus is generally of a greater diameter and roundness. This second species of spurious female her- maphroditism is not observed among the lower animals. B. Spurious hermaphroditism in the male— * Comp. Anat. vol. iii. p. 318. +; Pandect Medico-Legales, t.i. p. 38, Casus xii. t,Mém, sur les Hermaphr. p. 314-18, §_Anat, Pathol, liv. xiii, Pl. iv. HERMAPHRODITISM. Malformed males have been more often mis- taken for females than the reverse. The varieties of malformation in persons actually male, that are liable to lead to mistakes with regard to their true sex, appear to be, 1st, extrophy or extroversion of ‘te urinary bladder; 2d, ad- hesion of the inferior surface of the penis to the scrotum ; and 3d, and principally, fissure of the inferior part of the urethra and of the scrotum and perineum. 1. Extroversion of the uri bladder.— For a full description of this malformation we must refer to the articles BLappEer and Mon- srrosity. This malformation is known to occur more frequently in the male than in the female, and when present in the former it has occasionally given rise to a supposition of her- maphroditism, the red fungous mass formed by the mucous membrane of the protruded posterior wall of the bladder, and situated above the pubis, having been mistaken for the female vulva,—an error which has probably been the more readily committed the uterus and seminal ducts, and sometimes also, as in an instance described by A. Fraenkel,* a part of the intestinal canal opening upon the Surface of the exposed portion of bladder. In some instances of this malformation occurring in man, the external male sexual organs are ay imperfectly formed, or can scarcely be said to be at all present. In other cases the Scrotum is of the natural form, with the two testicles in it; and the penis is of considerable size, though almost always fissured on its upper surface from the epispadic or open state of the urethra. An example of supposed hermaphroditic malformation briefly described by Rueffe,+ which seems referable to this variety will be sufficient to illustrate it. “In the year 1519 an hermaphrodite or and us,” he remarks, “ was born at Zurich, Tfectly formed from the umbilicus upwards, but having at this part a red mass of flesh, beneath which were the female genitals, and also under and in their normal situation those of the male.” 2. Adhesion of the inferior surface of the penis to the scrotum by a band of inte, ts. —This state of so has occasionally given rise to the idea of hermaphroditism, the penis being so bound down as not to admit of erec- tion, and the urine passing in a direction downwards, so as to imitate the flow of it from aoe parts. n a boy of seven years of regardi whom Brand { was consulted, oe. penis =) confined in this manner to the scrotum by abnormal adhesions. He had been baptized and reared asa girl, but bya slight incision the adherent o was liberated, and the age were convinced of the mistake that the: committed in regard to the sex of their child. The difficulty of determining the true * De Organoram Generationis Deform, Rarissi- mi, Berlin, 1825, with a plate. t De Conceptu et Generatione Hominis, p. 44. _t Case of a i Alaa had been mistaken for a girl. Loudon, 1788, 691 sex of the boy was increased by the testicles not having descended into the scrotum. Wrisberg* mentions two similar instances in persons of the respective ages of nineteen and forty-six. He relieved the adherent penis in the first case by operation. 3. Fissure of the inferior part of the ure- thra, perineum, &c.—This species of mal- formation, which has perhaps more frequently than any other given rise to the idea of the rson affected with it being the subject of rmaphroditism, evidently consists in an arrest of the development of the external male sexual At an early stage of the development of the embryo, the various central sexual organs are, like all the other single organs situated on the median line of the body, found to be composed of two separate and similar halves, divided from each other by a vertical fissure, which, after the originally blind extremity of the intes- tinal canal has opened upon the perineum, forms a common aperture or cloaca for the intestinal canal, and also for the urinary and genital apparatus, both of which are, in their primary origin, prolongations from the lower part of that canal. After a time, (about the second month in the human embryo,) the opposite sides of this cloaca gradually approxi- mate, and throw out two corresponding folds, which by their union constitute a septum that separates the rectum from the canal or portion of the fissure, that still remains common to the urinary and generative organs; and, in the same way, by two similar and more anterior folds, the urethra of the female, and the pelvic portion of that of the male is subsequently produced. After this in the female the process of median reunion does not proceed further, and the primary perineal fissure remains, form- ing the vulva and vagina. In the male, how- ever, the development, when normal, goes on to a greater extent, and the sides of the opening become so far united as ultimately to leave only the comparatively contracted canal of the urethra to serve as a common passage for both the internal urinary and genital organs; and the situation of the line of junction of the opposite sides of the original perinzal cleft remains still marked out in the adult, by the raphé existing in the median line of the scrotum. The two lateral parts of the female clitoris unite together into one solid body, having on its under sur- face a slight groove or channel, indicative of the line of conjunction of its two component parts; and the urethra is left to open at the root of this imperforated organ. In the male, on the contrary, the two primitive halves of the penis, consolidated together at an early stage along the course of their upper surfaces, come, in the s of development, to unite inferiorly in such a manner with one another as to form a tubular gipogee of the pelvic portion of the canal of the urethra, which is gradually extended forwards along the body of the penis and ultimately through its glans. any of the malformations to which the * Comment, Med, &c, Arg. p. 534, 222 692 male genital organs are liable may be traced to stoppages in the above process of development, the character of the malformation depending upon the period of the development at which the arrest takes place, and varying consequently in degree from the existence of a cloaca or permanent primitive fissure common to the intestinal, urinary, and generative organs,* to that want of closure, to a greater or less extent in different instances, of the inferior surface of the canal of the urethra in the body of the penis, or in its glans, which is generally known under the name of hypospadias. When the development of the male organs is arrested, fomvadiainly after the two septa respectively separating the canals of the intestine and urethra from the original perinewal cleft are formed, and consequently when this perineal fissure and that running along the inferior surface of the penis are still open, the external genital parts often come to present at birth, and during the continuance of life, a striking resemblance to the conformation of the external organs of the female, and the resemblance is frequently rendered greater by the coexistence of other malformations of the male organs. In these cases the imperfect and undeveloped penis is generally of small size, and, at the same time, from being imperforate, may readily be mis- taken for the clitoris; the two halves of the divided scrotum have the appearance of the two labia externa; the two labia externa or nymphe are sometimes Vi sa by the lateral divisions of the penis forming two folds, which run backwarks along the internal surfaces of the split scrotum; and the cleft in the perineum corresponds in situation and direc- tion, and occasionally also in size and form, with the canal of the vagina; this cleft is generally lined also by a red mucous membrane that is kept, like the natural female parts, con- stantly moistened by the secretions of the follicles with which it is provided; its mucous membrane occasionally presents irregular eleva- tions imperfectly representing the caruncule myrtiformes; and, further, the opening of the urethra at the root of the diminutive and im- perforate penis serves still more to assimilate the malformed parts to the natural conformation of the female organs. In a number of cases, however, the apparent analogy to the female parts is rendered less striking by the perinzal cleft being small or altogether absent, the urethral orifice at the root of the penis often forming the only opening leading to the internal urinary and generative parts, and the halves of the scrotum in such instances being frequently more or less perfectly united. Generally the seminal ducts, and sometimes also the ducts of Cowper’s glands, are seen opening on the surface of the urethra or supposed vaginal canal, at a short distance from its external orifice. In males malformed in the manner described, the testicles are seldom found in the divided * See on this malformation in the human subject (the normal form of structure in birds, &c.) Meckel on Kloakbildung in his Path. Anat, Bd, i, s, 693, HERMAPHRODITISM. scrotum at birth, but commonly they descend into it through the inguinal rings towards the period of puberty; and in several instances on record, in which the sex of the individual had been mistaken for that of a female, the tumours formed in the groin at that time by the orgaus in their descent have been erroneously regarded and treated as hernial protrusions. At the same time it occasionally happens that with the descent of the testicles, and the arrival of puberty, the diminutive penis enlarges in size, and the individual assumes more or less fully the habits and attributes of the male. In several instances on record this change has, under venereal excitation, appeared to occur suddenly, and persons formerly reputed female have thus unexpectedly found themselves pro- vided with an erectile male penis. These various changes are occasionally postponed for a considerable period beyond the usual term of puberty. In a few rare instances one testicle only de- scends through the inguinal ring, and occasion- ally they both remain throughout life within the abdomen, in or near the situation in which they are originally developed, imitating in this ab- normal state the normal position of the same organs in many of the males among the lower animals. In a number of instances in which the testicles are thus retained within the cavity of the abdomen, they are found small and im- perfectly developed, and from the want of their usual physiological influence upon the consti- tution, the whole physical and moral character of the malformed individual frequently presents a considerable approximation to that of the female, or, as we should perhaps more justly express it, never attains the perfection of the male, but preserves that kind of common or neutral state exhibited by the constitution of both sexes before the specific sexual characters of each are developed at the time of puberty. Numerous curious examples of ‘mistakes having been committed with regard to the sex of males affected with the above species of mal- formation have now been put on record, from the time at which Iphis, the daughter of Ligdus, king of Crete, was conceived to be changed into a man by the miraculous interference of Isis, down to the present day. Pliny, (lib. vii. chap.iv.) has noticed several cases; and in the treatise of Duval on hermaphrodites a number of additional instances are collected from Livy, Trallian, and others, some of them no doubt invested (as most of the details regarding her- maphrodites in the older authors are) in much misrepresentation and fable, but others bearing every mark of accuracy and authenticity. In more modern times the sexes of individuals have often been mistaken in consequence of this variety of malformation. Jean Chroker* relates, in apparently the most authentic man- ner, the case of Magdelain Mugnoz, a nun of the order of St. Dominique in the town of Ubeda, who was changed, as he supposes, into a male, seven years afier having taken the vows. * Fax. Histor. cent. i. and Arnaud, Dissertation sur les Hermaphrodites, p. 200, HERMAPHRODITISM. He was expelled the convent, assumed the male dress, and took the name of Francois. The sequel of the story, as told by Chroker, would seem to shew that his sexual desires be- came extremely strong, and he is said to have been ultimately condemned, whether justly or not, under an accusation of rape. Portal* quotes from Tigeon the story of a person who was brought up as a female, and afterwards was pica} to be suddenly changed by a surprising metamorphosis into a male, and in citing this case Dr. Hodgkin, of London, mentions, on the authority of a friend, a recent instance of an equally sudden deve- lopment of the male sex in a previously reputed female. Similar instances in which the r sex of malformed males was ublenganbadhy vie. covered under the excitement of sexual jon at the period of puberty are mentioned by Pare, Tulpius, and others. Schweikard{ has recorded an instance of a person baptized and brought up as a female, and whose true sex was only at last disclosed by his requesting, at the age of forty-nine, per- mission to m a young woman then preg- nant by him. On examination it was dies: vered that the penis was slender and scarcely two inches long; the right testicle only had descended into the scrotum, and the urethra opened at the root of the penis, but its orifice was placed in such a manner that during mic- turition the urine was thrown along the groove or channel on the under surface of the penis, so as to appear to issue from its anterior extremity. The two halves of the scrotum were so far united that they left only a small oval opening between the anterior part of the raphé and the roots of the co cavernosa. In this open- me orifice of the urethra was situated. r. at has mentioned a case which appears to belong in all probability to the pre- sent division. The subject of it was twenty- four years of age. She had always passed in society as a woman, and came for copsultation to the Nottingham Hospital on account of her menses never having appeared ; a circumstance, however, that had in no way affected her health. The spurious vagina consisted of a cul-de-sac two inches in depth. The penis was of the size of the female clitoris, but there were no nymph. The labia were more pen- dulous than usual, and contained each of them a body resembling a testicle of a moderate size, with its cord. e look of the individual was remarkably masculine, with plain features, but no beard. The mamme resembled those of a woman. The person had no desire or partiality for either sex. Adelaide Preville, who had been married as a female, died in the Hétel Dieu of Paris. In examining the body of this individual after * Hist, de l’Anat. tom. ii. p. 52. a we of Guy’s Hospital Museum, part ii. sect. xi. t Hufeland’s Journal der Prak. Heilkunde. Bd. xvii. No. 18. _ Morbid Anatomy, p. 410, 2d edit. 693 death, Giraud* found that, ris i a perineal cleft or false vagina consisting of a cul-de-sac placed between the bladder and rectum, nothing else resembling the female sexual apparatus could be detected, while all the organs belong- ing to the male sex were present Cttot has described and represented (fig-289) acase of the present species of hermaphroditism in an individual whose history is remarkable. The person had lived ten years in the state of wedlock with three different men ; butatthe age of thirty-five an action of divorce was sat, 0 against her by her third husband, accusing of being affected with some disease of the sexual parts that rendered the connubial act on his part extremely difficult and painful. After some difference of opinion between the two medical men to whose professional examination the wife was submitted, it was at last consi- dered that she was in reality a male, and the case came at last under the investigation of the members of the Royal Medical College of Silesia, who confirmed this opinion. The im- = penis (6) was one inch and a half in ength; the perinwal fissure (¢) forming the false vagina was, at the posterior of its orifice, bounded by a distinct frenulum, but was of a size sufficient to receive the glans of the husband for an inch and a half in depth. This cavity, as well as the internal surfaces of the two lobes (aa) of the divided scrotum, were lined with a'vascular mucous membrane. At the bottom of it the round orifice of the urethra (d) was seen to open ; and at the same * Recueil Period. de la Soc. de Méd, tom, ii. p. 315, or Moureau’s cinyrteeen as Femme, t. i, ° ith a figure of the . : Pos Seltens Dosbashtongea zur Anatomie, &e, p. 123. 694 point a hard mass could be felt, probably con- sisting of the prostate gland; and more up- wards and outwards, nearly in the natural situation of the bulb, was seen the split urethra (c) with a row of three considerably sized open- ings (ff), 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 ofa 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, mamme, 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 lines 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 mamme 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 hemorrhage 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.t This person had * Observ. sur l’Hist, Nat. sur la Physique et sur la Peinture, tom. i. p. 18, with a plate. t Ephem. Nat. Curios, Dec, i, an. iii. p. 323. HERMAPHRODITISM. 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 pak curiosity with respect to the reality of is hermaphroditie character. At the same time, 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,t and Deliust described Michel-Anne Drouart as a male; Guyot,§ Ferrein,|| and Caldani{’ 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- pes in any marked degree doubtful, has ately been offered in the instance of Maria- Dorothée Duriée, or, as this individual was named in the latter years of his life, Charles Durge. While Metzgert+ 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,tt Mursinna,§§ Gall, Brookes,|||] and others /{ declared the sex of Duriée to be in reality female; and Stark,*** Mertens,t{+ and the Members of the Faculty of Medicine at Paris t{f were equally positive in regarding the indivi- dual as merely a malformed male. The dis- section of the body of Duriée 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. * Mém. de l’Acad. des Sc. 1750, p. 165. t Dissert. sur les Hermaphr. p. 298. t Frank, Sammlung. Th. viii. s. 398. Mém. de l’Acad. des Sc. 1756, p. 71. Ib. 1767, p. 205. Mem. della Societa Italiana, t. vii. p. 130, ** Arnaud, loc. cit. p. 298. tt Gericht.-medic. Abhandlungen, Bd. i. s. 177. # Journ. der Praktischen Heilkunde, Bd. xii. s. 170. § Journ. fiir die Chirurgie, Arzneikunde, &c, Bd. i. s. 555. | Medical Gazette for October, 1836. ” Von dem Neuangekommen. Hermaphrod. Berl. 1801. *** Neuen Archiv. fur die Geburtshiilfe. Bd. ii. s. 538. +ttBeschreibung der minnlichen Geschlechtstheile von M.D. Durrier. Leipzig, 1802, with two plates, ttt Med. Gaz. for October, 1836. oy ee HERMAPHRODITISM. 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 hypospadie male penis has usually beeu 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 perineum 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 ;+ and in the ram by the same author,{t and by Wagner,§ Wepfer,}| Stark,{ Gurlt,** Kauw Boerhaave,++ 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 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 perineum 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 * Mém. de l’Acad, de Turin. tom. v. p. 18, A Comment. Soc. Reg. Sc. Gotting. tom. i. p. 2, tab. i. t Ibid. p. 5, tab. ii. Ephem. Nat. Curios. Cent, i, ii, p. 235. iscell. Nat. Curios. Dec, i. An. iii. (1672,) p- 255. { Ibid. Dec. iii. Ann. v. vi., p. 669. ** Lehrbuch, p. 193. +t Nov. Comment. Acad. Petropolit. tom. i. (1750,) p. 315, tab. xi. tt Catalogue of Guy’s Hospital Museum, No. 695 the ram in the ion of Professor Dick of the Veterinary School of Edinburgh. There is another variety of malformation of the male one 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 ina state of erection, upon the posterior surface of the enlarged udder, and the imperfectly developed testicles are ge- — retained within va abdomen; or, if ey have passed out of that cavity, they are found situated in the substance of the udder. The vasa deferentia, prostate, and Cowper's glands are usually of their normal size and ap- pearance. This imperfect hermaphroditic for- Mation appears to not rare among horses, several instances of it in this animal having been now described by Arnaud,* Gohier,+ Volmar,t Pallas,§ Virey,|| and Gurlt.{ An- selmo** and Lecoqt+ have met with this variety of malformation in the bull; and Sandford tft 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 Diccia, are fur- nished with both male and female reproductive organs, placed either upon the same flower, or, as in the Linnzan class Monecia, upon different flowers in the same individual. In the class Polygamia various exceptional genera are included, that present indiscriminately u 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 monecious flowers, and the dicecious plants. From anormalities in developement, these normal conditions of the pos ty type in the different members of the vegetable 6s, Te are occasionally observed to be changed. us, among the Diccia, individual plants are some- times, in consequence of a true malformation, observed to assume an hermaphroditic type of structure; or, on the other band, in hermaphro- ditic plants more or fewer flowers are occa- * Arnaud sur les Hermaphrodites, P. 282. + Mém., et Observ. sur la Chir. et la Méd. Vet. tom. i. p. 18. Archiv. fiir Thierheilkunde, Bd. iii. s. 292. Beschaft. der Gesellschaft naturforch, Freande zu Berlin, Bd. iii. s. 296. Journal Compl. des Sc. Méd. tom. xv. p. 140, Lehrbuch der Path. Anat. Bd. ii. p. 189; and tab. viii. fig. 6. ** Mém. del’ Acad. des Sc. de Turin, tom. ix. p- 103. fig. 1-3. tt Journ, Prat. de Méd. Vet. 1827, p. 102. tt Med. and Phys. Journal, vol, ii. p. 305, with two drawings. . §§ Loc. ait. p. 191. 696, sionally found unisexual, in consequence of the arrested developement of one order of their sexual organs ; and again, though stil] morerarely, 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 Pre r physiological function of either or of oth 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 ofa single organ only of the opposite or 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, detmralry Qdly, 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 HERMAPHRODITISM. | 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 Melitea 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,+ the left side appeared externally male, and the right female, with a distinct line of separation through- outthe whole body. On dissection, Schultz dis- covered an ovarium — 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.f * Froriep’s Notizen, vol. x. p. 183. t Abhandlung. der Koenig. Akad. zu Berlin fiir 1825, s. 55. t See also drawings of the body and genital or- gans of an hermaphrodite Sphinx populi in Fischer’s Oryctographie du Gouvernement de Moscou (Mos- cow, 1830. ) HERMAPHRODITISM. A well-marked example of lateral herma- phroditism among the Crustacea has been re- corded by Dr. Nicholls.* In a lobster ( Asta- cus marinus) he found on the right side of the body a female sexual aperture im its normal Situation at the root of the third leg, and con- nected with a regularly formed oviduct, full of ova. On the left side of the animal there was - amale 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 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. Homet 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 Rathké{ 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 huso,t} and Esox lucius.tt 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 > + Phil. Trans. for 1823, Art, xii. ¢ Bemerkungen weber den Innern Bau der Pricke, s. 119. See also additional observations by the same author in Miiller’s Archiv fur Anatomie, &c. for 1836. Heft. ii. s. 171. The older error of Cavolini, who su 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 oe his having mistaken undeveloped portions of the ovaries for testicles. (fehnoigane's Skeletlose Thiere, s. 204; and Ab- dlangen. Konig. Akad, der Wissenschaft zu Berlin, 1825. p. 48.) Commercium Litter. Norim, 1734, Hebd. 39. Pipping, Vetensk, Akad, nya Handl. (1800. ) + xxi. s. 33, tab. i, fig. 1. uwenhoeck, Ex- —_- et Contempl. p. 150, Eph. Nat, Cur. Dec, nn. i. obs. 125. Du Hamel, Traité des Poissons, Part ii. p. 130. 4 Alischer, Breslau. Sammlung. 1720, p. 645; Morand, Mém. de l’Acad. des Sc. 1737. p. 72. Schwalbe, Commer, Lit. Norimb. 1734. p. 305. ** Marchant, Mém. de l’Acad. des Se. 1737. p. 12. Baster, onee Subcesiva, tom. i. p. 138. at Pallas, Reise durch Russe, &c. Theil. ii. s. ¢t Reaumur, Mém. de l’Acad. 1737. p. 51. io Nat. Cur, Dec. iii, ann. vii. and viii. 697 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 bas referred to a second and more ancient example of lateral hermaphroditism in the hen, mentioned by Heide.t The case, en- titled by the author “galli qui putabatur her- suphavdice 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 pes natu- rally formed. On the right side, a male vas deferens (d), of about half the normal length, * Naturgeschichte der Voegel, &c. Bd. ii, s. 1219, (1807). ; +A Mytali: subj est Centuria Obser. Amster. 1684, p. 193, obs. 95. 698 ran up from the cloaca to opposite the origin of the iliac vessels (c), and during this part of its course was bent into those short transverse zig- zag folds which characterise the structure of this part in the common cock. (See article Aves, vol. i. p. 354.) When it reached the middle third of the kidney (dd), it lost this particular form, became membranous (e), and after pro- ceeding upwards for about an inch, in the com- mon course of the canal, at last disappeared. The convoluted or contorted portion ran over a space of about two and a half inches, and if unrolled would have extended three or four times that length. Its canal was about the usual size of the same part in the perfect cock, and perhaps at some parts even more dilated. Its cavity was filled with a whitish seminal-looking albuminous fluid, which at first prevented a mercurial injection from readily passing through it. There was not any appa- rent vestige of a testicle. The fowl that was the subject of this malformation possessed in an imperfect degree the plumage, comb, spurs, and general appearance of the cock, and when young was considered to be a male until the time it commenced to lay eggs, which it did very constantly, except during the moulting season, up to the time of its death. Its eggs were remarked to be very large. They had re- peatedly been tried to be hatched, but always without success. The bird itself was never known to incubate. It was peculiar in its habits in so far that in the barn-yard it did not associate with the other poultry, and at night roosted sepa- rately from them. It crowed regularly, espe- cially in the morning, and often attempted copu- lation with the hens. In the second case, the ovaries and oviduct on the left side of the body were, as in the former example, natural in themselves; but in the mesometry of the oviduct, a tube of the size of the male vas deferens was found. This tube, like the normal vas deferens, was thrown into the distinctive angular folds. It ran for about an inch and a half through the upper portion of the mesometry, was blind at either extremity, and admitted of being injected with quicksilver. On the right side, there was also a male vas deferens, marked with the characte- ristic angular folds. The contorted portion of this canal only stretched in this instance to about an inch above the cloaca; but the folds were even stronger than in the first case, and the tube itself was rather more dilated. Above or anterior to this convoluted part, the tube be- came straight and membraneous, and ran up in this form for about two inches in its usual track over the abdominal surface of the kidney ; but there was not at its upper extremity any trace ofa testicle. This bird presented during life, in a very slight degree only, the appearance of a cock, its comb and spurs being even less developed than in the previous case. It shewed the same solitary habits in the poultry-yard. It layed eggs regularly. On three different occa- sions I had a number of them submitted to incubation, but in none of them was a chick produced. HERMAPHRODITISM. In the Quadruped, Schlump* has mentioned an instance of lateral hermaphroditie malfor- mation. In a young calf he found on the left side, under the kidney, a small testicle having attached to it a vas deferens, which was con- nected with the peritoneum towards the abdo- minal ring of the same side, and there became lost in the cellular texture of the part. An ovary and Fallopian tube, with an uterus consisting of a single horn only, were connected to the right side of the loins by a ligament. The neck of the uterus lost itself in the cellular substance beneath the rectum, and there was no vagina. The external organs were male, but imperfectly formed. The udder occupied the place of the scrotum. In the human subject several different in- stances of sexual malformation have now been met with referable to the head of lateral herma- phroditism. In these cases, along with a tes- ticle on one side, and an ovary on the other, there has generally co-existed a more or less per- fectly formed uterus. The external parts have differed in their sexual characters, in some in- stances being female, in others male, and in others again of a neutral or indeterminate type. In man, and in the higher —— we have not unfrequently exhibited to us a slight tendency to this unsymmetrical type of sexual structure constituting true lateral hermaphro- ditism in the testicle of one side only des- cending, whilst the other, in consequence of imperfect development, remains within the inguinal ring. In the single unsymmetrical ovary of most female birds and some fishes,+ we see a still nearer approach to the state; and it is worthy of remark, that among birds at least, the single ovary is always placed upon the left side. In lateral hermaphrodites in the hu- man subject, the left side also appears to be that on which we most frequently meet with the female type of the sexual organs. We shall divide the following cases according to the par- ticular sides which were respectively male and female in them. 1. Ovary on left side, and testes on the right.— a. M. Sue met, in 1746, with an instance of late- ral hermaphroditism in the human subject, in a young person of thirteen or fourteen years of age, whose case was the subject of a Thesis sustained by M. Morand.{ Of the internal = Archiv. fuer die Thierheilkunde, Bd. ii. Hft. ii. s. 204, + In the early embryo ofbirds, the ovaries are ori- ginally double, as pointed out by Emmert, (see Reil’s Archiv for 18113) and as was previously known = Wolff and Hochstetter, (Anat. Phil. tom. i. p. 9. .) : ¢ De Hermaphroditis, Paris, 1749. This, ac- cording to Arnaud, (p- 323,) is the same case of lateral hermaphroditism with that described by Lecat. If so, the latter author, (probably from drawing his description from memory, and not, as Morand seems to have done, from the parts placed before him,) has stated that along with the testicle and vas deferens on the one side, there existed a vesicula seminalis, and that both sides were provided with round ligaments, the one on the male side forming probably one of the two tubes described by Morand as arising from the testicle. © a ee Ss er rr Se HERMAPHRODITISM. genital organs, there existed on the left side avery distinct ovary, a round ligament which ran outwards to the groin of the same side, and a well-formed Fallopian tube with its usual fimbriated extremity. The other extre- mity of the Fallopian tube terminated in the fundus of the uterus, which occupied its usual situation between the bladder and rectum. On the right side, again, there was a slender elongated testicle, which had moved forwards to the c ding inguinal canal, but had not ed so far as to pass out of the ab- dominal cavity. On the superior part of the testicle was a body resembling the m sg and the testicle itself sent off two tubes, which afterwards united into one immediately before their insertion into the ome! bow eg ital organs were those of a padic male, ar ating life the person hed bans always looked upon as belonging to the male sex. e perineal canal or vagina terminated, between the scrotum and root of the imperforate penis, in a aa 4 small opening, which was common to it and to the meatus urinarius. 6,In 1754,* a young person of about eighteen years of age died in the Hotel Dieu of Paris; and in dissecting his body, the anatomist, Varole, found the reproductive organs malformed in the following manner. On the right side the scrotum contained a testicle, and the vas defe- rens arising from it opened, not as usual into the neck, but into the middle of the external border of the corresponding vesicula seminalis. On the eft side the scrotum was empty 5 and internally on this side there were found an ovary, a Fallopian tube with its fimbriated ex- tremity, a small oval uterus without a neck and somewhat flattened, and a broad and round ligament, the last of which ran outwards, and was lost in the cellular tissue of the left half of the scrotum. The vesicula seminalis on the right, and the imperfect uterus on the left side, communicated by a canal of an inch and a half in length. The external organs were male; but the penis was very small, had no corpus spongi- osum, and was imperforate for half an inch at its anterior or The mamme were as as in women of the same age. The indi- vidual had been regarded during life as a male. ¢. In 1825 the late Professor Rudolphit de- tailed to the Academy of Sciences at Berlin the case of an infant who was reported to have died seven days after birth, and whose sexual organs exhibited the following interesting in- stance of lateral hermaphroditic conformation. Meckel (Reil’s Archiv. Bd. xi. s. 322,) considers Morand’s and Lecat’s as two different cases, and ints out that what is described as the male side in the one, was the female in the other, and vice versa. Itis, perhaps, not unworthy of remark, that in the col d plate panying the translation of Morand’s case by Gautier, the male and female sides have been reversed from an error in the en- graving ; and this circumstance may have contribu- ted to mislead Legat in his description, provided he happened to look to this notice of the case. Mém. de la Soc, Méd, de Paris, tom. iv. p. 342. + Abhandlung. Konig, Akad. derWissenschaft, zu Berlin fiir 1825, s. 60. 699 On the left side were discovered an ovary (fig.291, a), without a distinct broad ligament, Fig. 291. Uterus (c) turned downwards and forwards to show its posterior surface and connections, &c. and a Fallopian tube (6), which communi- cated with the superior and left portion of an uterus (c). The left side of the scrotum (fig. 292, a), was empty; the right (6) contained a_ testicle (fig-291,d) furnished with ") an epididymis (e) and tor- wii tuous vas deferens(f). 4 Below the uterus there was a hard flattened ovoid body (fig. 291, g, and Jig. a. which, when divided was found to consist of a cavity with thick ietes, and was conaideda by Rudolphi — 2#¢ernal organs. as the prostate gland in a rudimentary state, The mouth of the uterus Fig. 293 (fig. 293, a) terminated be- : low in the parietes of this ovoid body, and on the right the vas deferens (d) penetrated into its sub- stance, but without open- ing into its cavity. At the inferior part of the uterus there was a true vagina (fig. 293, c), which termi- nated in a cul-de-sac. The anus, rectum, and other organs were natural. The external sexual parts were “de A male, but the penis was divided inferiorly (fig.292, c). The testicle and ovary were sup- plied with the two usual spermatic arteries (fig. 291, hh). . Under the present section of lateral herma- phroditism, we may also, according to Mayer’s report, include the celebrated case of Marie Derrier, or Charles Doerge.* This person was baptised and brought up as a female, but at forty years of age was persuaded to change his name and dress to those of aman. We have already alluded to the great diversity of opinion which was entertained by the medical men of Fig. 292. * Gazette Méd. de Paris (1836), no. 39. Lancet, v. i. for 1836-7, p. 140; or London Medical Ga- zette for October 29, 1836, 700 Europe in regard to the true sex of this indivi- dual. Even the different parts of his body were at one time referred to the male type, and at another time, and by other persons, to the fe- male. The pelvis was the only part that was generally considered as decidedly female, yet the inspection of the body after death by Pro- fessor Mayer shewed that even in this respect all were in error. Of the female sexual organs there existed an uterus, vagina, two Fallopian tubes, and an ovary ; and of the male, a testicle, and prostate gland and penis. The uterus was placed in its normal situation between the urinary bladder and rectum, but with its fundus directed in some degree to the left. The organ was extremely narrow, and two and a half inches in length. The cavity of its cervix presented on its inner surface some slight folds, but would scarcely admit a quill; the cavity of its fundus was nearly half an inch across. The small canals of two Fallopian tubes opened into the fundus uteri. Their abdominal extremitics were shut, but the corpora fimbriata were present. Near the extremity of the right Fallopian tube, which was four inches and four lines in length, a small flattened almond-shaped body was placed, which on examination proved to be distinctly a testi- cle. It was completely enveloped in perito- neum, and received a cord composed of muscu- lar fibres, and of a spermatic vein and artery. Its internal structure was yellow and filamen- tous, like that of the testicle, and its seminiferous tubes could be easily separated. The left Fallo- pian tube was an inch shorter than the right; and a little outside and behind its abdominal extremity another small flattened body was found inclosed in the peritoneum. It resembled an ovary rather than a testicle. Its tissue was composed of small granules conglomerated together. The penis was two inches and nine lines in length, and was for the greater part concealed underneath the mons veneris. During life it was capable of erection, and was then elongated to more than three inches. The pre- puce covered only half the glans. There was not any corpus spongiosum. A fossa or groove, representing an urethral canal divided inferiorly, ran along the under surface of the penis. The two folds of skin forming the sides of the groove separated from each other posteriorly, and might be compared to nymphe. Towards the root of the penis, by uniting inferiorly with a puckering of the skin of the labia majora or divided halves of the scrotum, they formed a circular orifice not larger than a quill, having some bodies, supposed to be vestiges of the ca- runcule myrtiformes, at its lower edge, and lead- ing to a short vestibule, or common canal, into which the urethra, surrounded by a firm but small prostate, entered from above, and the va- gina, encircled at its entrance by a vascular ring of varicose veins, opened from below. The vagina was two inches and eight lines in length, and only ten lines at its greatest breadth. Its inner surface was somewhat wrinkled an- teriorly, but smooth behind. It terminated above in a kind of spongy isthmus representing the blind orifice of the uterus, and from four to HERMAPHRODITISM. six lines in length. The diameters and form of the pelvis were, on dissection, found to be most evidently masculine. The general character of Doerge was a mix- ture of the male and female type. When be- tween twenty and thirty, he had been examined by different medical meninGermany, France, and England, and, as we have already mentioned, the most contradictory opinions were offered upon his real sex. The breasts were not much developed, and there was no distinct mammary glandular structure. His stature was small (five feet). As he had advanced in age, his voice had become more firm and grave, and a slight trace of beard had a peared; but his head and face presented the aspect of that of an old woman. His neck was short, and the thyroid cartilage did not project much: his chest was fat and full. During the last few years of his life he was subject to epistaxis and hemorrhoids, but did not present any trace of sanguineous discharge from the genital organs,—a phenomenon which was alleged to have manifested itself three times during his twentieth year. : The right hemispheres of the cerebrum and cerebellum, particularly that of the latter, were smaller and less developed than the left, and the left side of the occiput was externally more ear one than the right. He is stated by rofessor Mayer to have shewn a certain predi- lection for females, without, however, feeling any sexual desire. 2. ‘Testicle on the left, and ovary on the right side.—An instance of malformation of the reproductive organs minutely described by aret,* and which is in all its more essential anatomical points an example of lateral herma= phroditism, may be included under this head. a. The subject of the case (Hubert Jean Pierre) died in the hospital at Dijon in 1767, at the age of seventeen. On the left side a perfect testicle was discovered with its usual spermatic vessels, vas deferens, and vesicula seminalis, all occupying the natural situation in which they are placed in the male adult. The vesicula seminalis contained a fluid of the colour and consistence of semen. On the right side an oblong cystic tumour was found lying in the iliac fossa, and stretching outwards into the inguinal region. On opening ita quantity of reddish limpid fluid escaped, and then the solid contents of the tumour were seen to consist of a somewhat flattened body, that gave off from the upper part from its right side a short Fallopian tube; and at the fimbriated extremity of this tube an ovary of the natural size, consistence, and figure, was situated. The roundish shaped body to which the tube was attached was about an inch and a half in its greatest, and an inch in its smallest diameter. It contained in its centre a small cavity continuous with that of the tube,—a circumstance, which, along with the structure of its walls, left little doubt that the body itself was an imperfectly formed uterus. No other opening except that of the tube could be traced into its cavity. Its external surface * Mém, de I’ Acad. de Dijon, t. ii. p. 157. HERMAPHRODITISM. was attached to the ovary by a kind of ligament. ‘On this same side of the body (the right) there existed also a vesicula seminalis, but smaller and more shrivelled than that on the left, It gave off a vas deferens, which became gradu- ally smaller as it was traced backwards, and at last disappeared altogether without being con- nected with any structure resembling a testi- cle. In regard to the external organs of generation, the penis was four inches long and imperforate, but in all other respects per- fectly formed, It possessed a corpus spongi- osum, which does not exist in the female clitoris. On raising the penis, it was observed to cover a large fissure, the sides of which resembled the labia of a female. In the left labium or left half of the scrotum the testicle already alluded to was placed, but there was none in the right. hen the labia were Separated, two red spongy bodies were seen, resembling the nymphe in appearance, and seemingly consisting of the sides of the split urethra. Between these bodies and at their upper the urethra opened as in the female ; while below there was a very narrow aperture covered by a semilunar membrane, and _pre- Senting on one side of its entrance a small ex- erescence somewhat resembling in figure a caruncula myrtiformis. This orifice led into a membranous canal or cul-de-sac an inch in depth, and half an inch in diameter. On the lower part of this canal the verumontanum and orifices of the seminal ducts of both sides were discovered. During life Pierre had been considered a male, but was not known to have shown any partiality for the female sex. His counte- hance was more delicate than what we ordi- rds see in the male sex. There was no on the face ; the larynx was not enlarged as in man; and the mamme, each of which was furnished with a very large areola, were of @ moderate size and roundish form. The con- figuration of the lower part of the body was more decidedly masculine, and there was none of that enlargement of the buttocks and projection of the thighs, from the increased width of the pelvis, which is observable in young females. In this case we have on the left side of the body male sexual organs, consisting of a per- fect testicle, vas deferens,and vesicula seminalis. On the right side, again, we havea female ovary and Fallopian tube with a rudimentary uterus, together with an imperfect male vesicula semi- nalis and vas deferens. Arnaud mentions a v imperfect form of lateral hermai hreiditisin to having been re- cognised by M. Boudou, surgeon to the Hotel- Dieu of Paris, on the person of a monk who died in that hospital in 1726. The external ital parts were those of a hypospadic male. ‘one of the halves of the scrotum a testicle was found ; the other was empty. The seminal canals and vesicule seminales on the side on which the perfect testicle existed were natural in their course and situation. Those of the Opposite side lost themselves between the 701 bladder and rectum in a small body, which, in M. Boudou’s opinion, wasa shrunk uterus.” Among the ape cases of lateral herma- phroditism in the human subject, there are four in which the left side, and one only in which the right was the female. In the last instance quoted from Boudou the respective sides on which the male and female organs were placed are not stated by Arnaud. B. Transverse hermaphroditism—In the variety of hermaphroditic malformation which we have last considered, we have found upon the same individual the reproductive organs of one side disagreeing in their sexual type from those of the other. In the present division we have a similar sexual antagonism following a different direction ; for supposing the internal sexual apparatus to be divided from the external by a transverse line, we have, in trans- verse hermaphroditism, on each side of this partition, organs of an opposite sexual type : in other words, the organs of reproduction (in the more correct sense of the word) or the internal sexual organs do not, in the present species of hermaphroditism, correspond in type with the organs of copulation, or the external sexual parts,—a circumstance the occasional occurrence of which tends to shew that these two portions of the generative apparatus are in some degree independent of one another in their normal development and existence, and consequently also in their abnormal formations. Transverse hermaphroditism varies in its character according to the relative positions occupied by the co-existing male and female organs; the external organs, or all those ex- terior to the supposed transverse line, being sometimes female, and the internal male, and vice vers. 1. Transverse hermaphroditism with the external sexual organs of the female type—In the cases included under this division, the ex- ternal genital organs consist of a clitoris, vagina, and uterus; the uterus is often rudi- mentary, and sometimes altogether absent and replaced by the male vesicule seminales. The male internal organs are the testicles, generally small and imperfectly developed, and placed either within or without the abdomen, with vasa deferentia terminating in the uterus and vagina. This variety of sexual malformation has been repeatedly observed among our domestic uadrupeds, particularly among black cattle. r. John Hunter, in an essay read before the Royal Society in 1779, and published in their Transactions,+ and in his Observations on the Animal Economy, shewed that, (as had been long known among agriculturists,) when among black cattle the cow brings forth twin calves, one of them a male, and the other apparently a female, the male is a perfect bull calf, but the female, while it has all the external marks of a cow-calf, as the teats and udder, is still, with . a few exceptions, imperfectly formed in its * Arnaud, loc. cit. p. 283. t Vol. xix. 702 internal sexual organs, and very generally pre- sents a mixture of the organs of the two sexes in various degrees. Such hermaphroditic twin cattle have long been distinguished in this country under the name of free-martins. In some exceptional cases only have they been observed capable of breeding; and generally they shew no sexual desire for the bull, or the bull for them. In appearance they resemble the ox or spayed heifer, and have a similar, or still greater disposition to become fat under the use of good food. In the paper to which we have referred, Mr. Hunter has described the dissection of three free-martins : and one of these seems to belong to our present division of female transverse hermaphroditism. The clitoris and external parts appear to have been strictly of the female type, and there was a small udder with four teats. The vagina terminated in a blind end a little beyond the opening of the urethra, and from this point the vagina and uterus were im- pervious. The uterus at its superior part divided into two horns, and at the termi- nations of these horns, not ovaria, but bodies resembling the male testicles were found. These bodies had nota perfect internal structure like that of testicles, but resembled these organs in so far that, 1st, they were nearly as large as the male testes, and much larger than the female ovaries; 2nd, they were supplied with tortuous spermatic arteries like those of the bull or rigdil; and 3d, cremaster muscles passed up to them, as in rigdils, from the abdominal rings. There were two small vesicule semi- nales placed behind between the bladder and uterus, with their ducts opening into the vagina. Nothing, according to Mr. Hunter, similar to the vasa deferentia was present; but Gurlt is inclined to believe that the parts which Mr. Hunter has described as the horns ofthe uterus were really the deferent vessels. Professor Gurlt* has himself given, from a preperatian in the Museum of the Berlin eterinary School, the accompanying sketch of the malformed sexual organs of a five-year old free-martin, (fig. 294,) which presents to us an illustration of Mr. Hunter’s supposed mistake, at the same time that it affords a well-marked example of transverse hermaphroditism. The detail of the anatomical peculiarities of the case has been unfortunately omitted by the author, but from the short explanationsappended to the drawing, it appears that the clitoris (a) and external pudenda (b) were perfectly feminine, and that the vagina, short and funnel- shaped, terminated at its superior contracted extremity in two vasa deferentia (ccc), which were carried upwards ina duplicature of peri- tonzum (d d) resembling the broad ligament, until they joined the unrolled and lengthened epididymes (¢ e) of two small testicles (f/f) placed in the position of the ovaries. Near the junction of the vagina and vasa deferentia bodies resembling the male vesiculz seminales * Lehrbuch der Pathol, Anat. d. Saug. Th. Bd, ii. S. 186, HERMAPHRODITISM. (g ¢) and Cowper’s glands (A h) were situated, and the urethral canal (i) opened into the vagina and was shorter than it usually is in the cow. We have found upon a free-martin cow a state of the sexual apparatus very much re- sembling that figured in the above case by Professor Gurlt. The two vasa deferentia, as they ran in the duplicature of the peritoneum, had very much the appearance and shape of an imperfectly developed uterus. The vesicule seminales were large ;_the vasa deferentia were quite impervious throughout their whole course ; and the bodies placed at their abdominal ex- tremities were large, but of so indeterminate a Structure as not to enable us to pronounce them to be either true testicles or ovaries. M. Geoffroy St. Hilaire published in 1834 a very distinct case of an hermaphroditic goat which had two male testicles and epididymes with a two-horned uterus and female external parts.* M. Isidore St. Hilairet mentions a nearly analogous case in the same animal, and quotes a third from Bomare which was ob- served upon a deer.f : Nouy. Ann, du Museum d’Hist. Nat, t. ii, p. +: Histoire des Anomalies, t. ii. p. 128, ¢ Joum. de Phys, t. vi. p. 501. SS HERMAPHRODITISM. To the present division of transverse herma- phroditic malformation with external female and internal male o » we may probably also refer the case of the hermaphrodite dog de- tailed by Sir E. Home,* and three instances in the sheep described by Ruysch,+ Herholdt,t and Gurls In all these instances imperfectly developed testicles were situated either within the abdomen or without it upon the udder, at the same time that the external parts exhibited in a more or less marked degree the peculiarities of the female sex ; the vagina was, however, nar- rower, and the clitoris more developed than in the perfectly formed female; and in the dog mentioned by Home, this latter organ was very large, being three quarters of an inch long, and half an inch broad, but still it could not pro- perly be considered as an imperfect penis, since the bone, which forms the distinguishing mark of that organ in the dog, was wanting. Few well-marked instances of transverse hermaphroditism with external female organs have been hitherto described as observed in the human subject, unless we regard as an approach to it the numerous cases, already reft to, of spurious hermaphroditic malformation in the male from hypospadic division of the urethra, scrotum, and perineum. a. In his essay on hermaphroditism, how- ever, Steghlehner|| has detailed at great length the particulars of a case belonging to the present variety, which he met with on the body of a woman who died of phthisis at the age of twenty-three. The external sexual organs were all of the female type and in general well formed, though the clitoris and nymphz were perhaps smaller than natural, and the orificium vagine was rather contracted and half shut up by ahymen. The fossa navicularis was very distinct, and the vagina normally situated, but extremely short and narrow. Its internal sur- face presented an appearance of transverse and longitudinal ruge, but its upper extremity formed a blind sac, and no traces could be found beyond it of the uterus, nor indeed any vestiges whatever of the other internal female organs, the ovaries and Fallopian tubes. On more minute examination a testicle with its spermatic cord was found in each inguinal region, placed outside the external ring, and surrounded with their cremaster muscles and vaginal coats. The testicles were flaccid and small, but their internal structure and that of their epididymes was natural; and the slender pervious vasa deferentia arising from them entered the abdomen, descended into the pelvis, and were joined behind the urinary bladder by two vesicule seminales of considerable size. Their common ejaculatory ducts opened into the vagina. The form of the thorax and pelvis, and of the body in general, was feminine ; and ze Phil. Trans. for 1795, p. 157. Comp. Anat. ii. 323. t Thesaur, Anat. viii. n.c. iii, tab. 115, ? Viborg’s Sammlungs fuer Thi (1797.) 8. 20. § Lehrbuch, &c. Bd. ii, s, 186. tab. ix. 2, and xxii. s. 2, || Tract. de Hermaphr, natura, p. 120, 703 the mamme and oo were well developed, but the larynx was rather more protuberant than in females, and the voice approached in tone to that of aman. There had never been any menstrual discharge, but the periodical moli- mina indicative of its appearance were said to have been observed regularly. There were some hemorrhoidal tumours situated around the anus. b. If possible a still more perfect example of the present variety of transverse hermaphro- ditism in the human subject has lately been observed at Naples. The malformation occurred in the person of an individual Maria E. Arsano, who died at the age of eighty in one of the pauper charities at Naples, and who had passed through life as a female and been married as such. No suspicion of the malformation existed during life, and it was only at first accidentally discovered in preparing the dead body for demonstration in the anatomical theatre of Professor Ricco, who afterwards carefully dissected the malformed parts in com- pony with Professors Sorrentino and Grosetti- e have taken the following account and sketches from Ricco’s published description of the case.* The external organs of generation were those of the female in their natural or normal state, consisting of the mons veneris with a scanty quantity of hair (fig. 295, a); of the labia ex- terna (fig. 295 & 296, bb ) naturally formed, and the nymphe (fig. 295 & 296, d d); of the clitoris (fig.295 & 296, c), which was perfectly imperforate, and of the ordinary size of the same organ in the adult female; of the orifice of the urethra (fig. 295 & 296, e) situated be- low the clitoris; and of the os vagine (fig. 295 & 296, f), which was of the usual size and diameter. Altogether the aperture of the vulva was natural. The canal of the urethra was of the usual length, as seen at u in the section * Cenno Storico su di un’ Neutro-Uomo, p. 5, 7. 704 of the pelvis represented in fig. 296, in which s marks the divided symphysis pubis, and p the Fig. 296. peritoneum. The os vagine shewed no vestiges of the membrane of the hymen, or, in other words, was without caruncule myrtiformes. The canal of the vagina (fig. 296, v.) was about two inches long, but without ruge, and it ter- minated internally in a completely blind extre- mity or cul-de-sac. The uterus was entirely wanting, as were also the Fallopian tubes and uterine ligaments. The internal organs of reproduction were, on the other hand, completely male. The two testicles (fig. 295, g g) were situated in the region of the pubis, and were scarcely clear of the inguinal rings. They were of the usual ovoid figure, and natural in size. They had internally the structure of the tubuli seminiferi, but it was not well developed. The spermatic cords were quite normal both in regard to their composition and the origin and course of their bloodvessels. The right spermatic artery (fig. 295, 1) arose, as usual, from the renal, and the corresponding vein (m), after forming the pampiniform plexus (k), opened into the vena cava inferior; while on the left side the artery (2) arose from the aorta, and the vein (m) ter- minated in the left emulgent. The epididymes of the testes were also of the usual vermiform figure, and the corresponding vasa deferentia (fig. 295 & 296 hh) coursed towards their vesi- cule seminales (fig. 296, 7), and terminated in an attenuated membranous expansion without any external aperture or ducti ejaculatorii. The vesicule seminales (see the left one j in Jig. 296) were placed between the urinary blad- der (0) and rectum (7); they were smaller and more shrunk than those of the adult male, though certainly they preserved their naturally oblong form. Their internal hollow or tubular structure was indistinct. The prostate gland was not present. The urinary bladder (0) and ureters (n n), the rectum (7), and the other intestinal viscera, with the abdominal blood- vessels (s, the aorta, ¢, the vena cava, fig. 295) seem to have been all quite natural. The head of the above individual was of the usual size, the neck long, and the stature ordinary. The periphery of the thorax was so HERMAPHRODITISM. expanded as almost to equal that of the male, notwithstanding the presence of well pro- nounced mamme. The face, although entirely free from hair, had yet neither the expression of that of a female nor of a male, but shewed more of that mixed character which is seen in the eunuch. The pelvis was altogether that of a male in its form and dimensions, and the limbs were perfectly masculine. According to information collected after death, the voice was deep, and the temperament strong and firm. Though there was never any menstruation, yet, from being constantly employed in domestic occupation, the mental character was feminine, and the married state had been willingly entered ’ into. 2. Transverse hermaphroditism with the ex- ternal sexual organs of the male type-—The male organs that are present consist of the penis, which is provided with a regular formed prepuce, glans, corpora cavernosa, and corpus spongiosum, with the urethra perforating it, and of the prostate gland, verumontanum, &c. The co-existing female organs are the ovaries, the Fallopian tubes with their infundibula, and the uterus. We are not aware of any recorded instances of this variety of hermaphroditic malformation among the lower animals. We have already, under the head of spurious hermaphroditism in the female from enlargement of the clitoris, &c., mentioned several cases, in which, from excessive developement, the external organs in women had assumed some of the characters of the corresponding parts in man; but the two following cases described by Professors Esch- richt of Copenhagen, and Bouillaud of Paris, present instances of malformation in which the more exterior sexual organs were all formed upon the male, and the internal upon the female type. a. The subject of the case described by Eschricht* was a twin child that died very shortly after birth, and in whom the external sexual organs were of the male type, and the internal female. The penis (fig. 297, a) and scrotum (b) were well developed, but the usual raphé seen upon the latter was absent. The urethral canal of the glans and body of the penis was pervious throughout, and admitted of a sound being easily passed into the bladder. The glans was remarkably thin and slender. The prepuce could be easily pushed back. No testicles could be felt in the scrotum, and in- ternally there was an uterus with Fallopian tubes and ovaries. The uterus (c) was about an inch in length, and had the general form presented by this organ in female infants. It contained a cavity marked with ruge, but had no orifice inferiorly, nor any vagina attached to it. Its blind or imperforate neck was firmly attached to the posterior walls of the urinary bladder (g), while its fundus was directed very obliquely downwards and over to the left side. From the left side of the fundus of the uterus a twisted Fallopian tube (d) proceeded, having * Miiller’s Archiv fuer Anatomie, &c. 1836, Heft ii. : HERMAPHRODITISM. well developed fimbriw (e) at its abdominal extremity, and the broad ligament or fold of peritoneum along which it ran contained an oblong soft body (7), (which Eschrichtconsidered as distinctly an ovary,) and a round ligament that took its course through the inguinal canal of the same side. On the right side an ovary (Ak) and Fallopian tube (f) were likewise dis- covered, but they were displaced and separated from the body of the uterus. The ovary lay in the iliac region, and above it and towards its outer side was placed the fimbriated extremity of the corresponding Fallopian tube. The tube presented towards this extremity a vesicular swelling of the size of a small pea, which lled with admitted of being inflated and Poet through a small opening between fimbriez. Below this it was impervious, and apparently diverged off into two prolonga- tions, one of which (the round ligament) passed down into the inguinal canal, and the other crossed over with a fold of peritonxum to where the rectum and urinary bladder were preter- naturally connected together. Professor Jacob- son —— that this latter part was a rudi- ment of the right half or horn of the uterus. It may perhaps, however, be more proper! arded as the commencement of the right Fallopian tube, and in this case it would, if continued onwards, have been joined to the neck of the uterus,—an arrangement which would be quite in accordance with the usual deep and displaced origin of one of the tubes in instances of congenital obliquity of the uterus. The child was malformed in other respects also. The anus was imperforate, and the rectum (n) opened into the urinary bladder, which was very contracted. The kidneys (m) were irregularly formed, and lay near the pro- montory of the sacrum. There was an acces- sory spleen, and the formation of the heart and VOL, II. 705 1 vessels was abnormal. The other twin child was well formed and lived. 6. The case of transverse hermaphroditism observed by Bouillaud* was even still better marked than that of Eschricht. Valmont, the individual who was the subject of it, died in one of the hospitals of Paris of the epidemic cholera. He was a hatter by trade, and had been married as a male. No further particulars of his history or habits could be obtained. The following was found by MM. Manec and Bouillaud to be the state of the external and internal sexual organs. Externally there was a penis (fig. 298) of a Fig. 298. medium size, terminating in a regularly formed glans (a), and furnished with a prepuce (6). The urethra (fig. 299, bb) opened on the inferior side of the glans (fig. 298 & 299, a). In its course from this point backwards to the bladder, it perfectly resembled the urethra of the male, and was surrounded at its origin by a well- formed prostate gland (fig.299, k k). Cowper's glands were also present (fig. 298, d). The verumontanum or caput gallinaginis was dis- tinct, as well as the orifices of the prostatic follicles ; but the usual openings of the seminal canals could not be found. The corpus spon- giosum urethre (fig. 298, g) and the corpora cavernosa (fig. 299, mm) were as well deve- loped as in the perfect male subject. The scrotum was small, and did not contain any testicles; it presented on its middle a line or raphé extending from the b geo to the anus, and which was harder and better marked than it usually is upon male subjects. The various muscles of the male perineum (fig. 298, ¢ c) were present, and very perfectly formed. The constrictores urine muscles (¢) were particularly long and thick. In the cavity of the pelvis two ovaries (fig. 299, dd), similar in form and_ structure, according to M. Manec, to those of a girl of fifteen or sixteen years of age, or (to adopt * Journ. Hebdom. de Méd., tom. x. p. 466. “« Exposition Raisonnée d’un cas de nouvelle et singuliére variété d’hermaphrodisme observée chez Vhomme.” : 3A 706 Fig. 299. M. Bouillaud’s statement) two bodies in some sort fibrous, and perhaps intermediate in their structure between ovaries and testicles, were found along with two Fallopian tubes (fig. 299, gg), having each a fimbriated ex- tremity at one end, and opening by the other into the cavity of an uterus () which occupied the usual situation of that organ in the female, and opened inferiorly into a kind of vagina (e). The internal surface of the uterus showed the usual arborescent wrinkles of this organ in the unimpregnated state ; the os tince was regularly formed ; the vagina was about two inches long, and of a middle size, and presented internally numerous ridges, such as are met with in virgins. This canal, when opposite the neck of the bladder at f, became much contracted, and was continued downwards in the form of a small tube to the membraneous portion of the urethra, into which it entered by a narrow orifice. The broad ligaments of the uterus were normally formed; the round ligaments passed through the inguinal canal accompanied each by an artery larger than that of the correspond- ing one in the female sex. The external ap nce and form of Valmont are described by M. Bouillaud as having been intermediate between those of the male and female sex. The stature was short; the mam- mary glands and nipples were well developed ; the face was bearded; but the general phy- siognomy was still delicate. The body was fat; the hands and feet were small; the pelvis was shallow; and the haunches were wider than in a well-formed man. HNERMAPHRODITISM. C. Double or vertical hermaphroditism.— In the two divisions or orders of true herma- phroditism which have been already considered, we have seen re-united upon the body of the same individual more or fewer of the organs of the two sexes, but so arranged as not neces- sarily at least to present the occurrence of actual duplicity in any of the corresponding male and female parts. In both lateral and trans- verse hermaphroditism the type of the sexual apparatus is in fact single in so far that it con- sists, in almost all cases, in the presence at one part of an organ or organs differing in sexual type from those that are present at other parts, without there necessarily co-existing at any one point the two corresponding male and female organs. In the present or third variety, however, of true hermaphroditism, we come to a tendency to actual sexual duplicity,, in the co-existence of two or more of the ana- logous organs of the two sexes upon the same side, or in the same vertical line of the body. For, supposing we viewed, either from before or behind, the reproductive organs belonging to the two sexes all stretched out upon the same erect plane, so that their corresponding organs should be exactly superimposed upon one another,—as the two female ovaries upon the two male testicles, the Fallopian tubes upon the vasa deferentia, the uterus upon the vesi- cule seminales and prostate gland, &c.,—we should find in vertical or double hermaphro- ditism more or fewer of those analogous organs of the two sexes that were thus placed upon one another, and that consequently lay in the same vertical line, or upon the same side of the body, co-existing together at the same time upon the same individual. Double, vertical, or complex hermaphro- ditism differs much in variety and degree in different cases, from the imperfect repetition of two only of the corresponding organs of the male and female upon the same body, to the reunion or co-existence of almost all the genital organs of both sexes upon one individual. For the purpose of contrasting and collect- ing together as much as possible the more ana- logous cases, we shall arrange the instances of double hermaphroditism under three genera or divisions ; the first including cases in which there co-existed a female uterus and male vesi- cule seminales, with a general female type; the second, those in which a female uterus, occasionally provided with Fallopian tubes, was added to an organization that was in other respects essentially male; and the ¢hird com- prebending all examples in which ovaries and testicles are alleged to have been repeated toge- ther upon one or both sides of the body. Other divisions of double hermaphroditism may be- come necessary under the accumulation of new varieties of cases, but we believe it will be possible to arrange all the instances hitherto recorded under one or other of the above di- visions. In classifying and describing these instances we shall in the meanwhile offer no observations on the probable anatomical mis- takes that have been committed in the exami- a i te ES Oe HERMAPHRODITISM. nation of individual cases. We reserve this important subject for special consideration under a separate head, i we shall endea- vour to shew the numerous sources of error with which the observation of individual ex- amples and varieties of complex hermaphro- ditism is beset. — 1. Male vesicule seminales, §c. superadded to organs of a female sexual type—In this first nus of double hermaphroditism we find two female ovaries, or bodies resembling ovaries, and an imperfect uterus co-existing with two male vesicule seminales, which are occasion- ally accompanied also with rudiments of the vasa deferentia. One of the free-martins de- scribed by Mr. Hunter® is referable to this variety of double hermaphroditism. The ex- ternal genital organs and mamme resembled those of the cow, but were smaller in size. The vagina, beyond the opening of the urethra into it, was, with the uterus itself, impervious, The imperfect uterus divided into two horns, at the end of which were the ovaria. On each side of the uterus there was an interrupted vas deferens broken off in several places ; and be- tween the bladder and vagina these vasa de- ferentia terminated in two vesiculw seminales. The ducts from the vesicule and the vasa de- ferentia opened into the vagina. In this in- Stance we have all the female organs present, but imperfect in their development; and at the same time there is superadded to them a tubu- lar structure, formed, according to Mr. Hun- ter’s opinion, of the male vesicule seminales and vasa deferentia. We have met with a free-martin cow, in which upon dissection we found an arrange- Ment of sexual parts very similar to that described in the preceding case. The uterus, however, though small, was pervious for a distance of some inches above the ina; and at the abdominal end of each blind Fal- lopian tube there was a dilated sac of con- siderable size lined by peritoneum, and open- ing into the abdominal cavity by a small orifice. ese sacs we considered as abortive attempts at the formation of the fimbriated extremities. The imperfect bodies which we considered as testicles were placed near the cavities which we mention, in the situation of the ovaries. They were small in size, and of an oblong shape. On a section being made of them, ‘they shewed internally a kind of dense ho- weed yellow tissue, dotted or crossed ith strongly marked white lines. The vasa deferentia could be traced along each side of the uterus in the form of broken dense cords. The vesicule seminales were large and partially hollow, and near them on each side there was an oblong body of considerable size, having ‘the ot ge of Cowper's glands. The tubes from them, and from the vesicule seminales, opened near the os tince into a vagina of nearly the usual size. fi 2. An imperfect female uterus, $c. super- added to a sexual organization essentially seal. * See An. Econ, p. 64, Mr.Well’s free-martin. 707 —In the cases included under this second division of double hermaphroditism there exist a male testicle, or testicles, vasa deferentia, and yesicule seminales, along with a female uterus, The uterus occupies its normal situ- ation between the bladder and rectum. It is sometimes defectively developed, and of a membranous structure; and occasionally it is eS sk 8 with Fallopian tubes, or, in the quadruped, with cornua. The cavity of the uterus communicates with a vagina that either Opens in its usual situation externally, or, as happens more frequently, joins the male ure- thra. In some cases the vagina is wanting, and the uterus opens directly into the canal of the urethra. Several cases of sexual malformation in the ram, goat, and dog referable to this variety of double hermaphroditism have been described by different authors; and various analogous instances have now also been observed in the human subject. Ina lamb described and delineated by Mr. Thomas,* all the external parts were male, but the scrotum was divided or hypospadic. In- ternally there were two perfect male testicles in the situation of the ovaries, with their epidi- dymes, vasa deferentia, and vesicule seminales ; and a well-formed two-horned uterus furnished with its usual ligaments, and with Fallopian tubes that ran up and terminated in a tortuous convoluted manner upon the testicles. The body of the uterus possessed the common rugose structure, but the horns were lined by a smooth membrane without their usual glandular bodies internally, At the anterior extremity of the fundus uteri, a thick semilunar valve, which seemed to correspond to the os tince, passed across and hardly allowed a fine probe to be entered over its upper edge. The ina scarcely existed, and formed only a short smooth pouch terminating below in a cul-de- sac. The male vesicule seminales and vasa deferentia entered the male urethra in their normal situation at the caput gallinaginis. Gurltt has described and delineated the sexual parts of a goat in which all the inter- nal male genital organs, with the exception of Cowper's glands, were found (fig. 300). There was also present an uterus (e) provided with long but narrow and curved cornua (f/f), that accompanied the vasa deferentia and tes- ticles through the abdominal rings, and ended blind at the epididymes. The testicles lay externally upon the udder, which was of con- siderable size. The scrotum was absent; the penis (g) was short, tortuous, and imperforate ; and there was a fissure in the perineum into which the urethra (h) opened. Stellatif has recorded an analogous case in the same animal. The male sexual organs * London Med. and Phys. Journ. vol. ii. (1799), p. 1, with a good drawing of the malformed organs of generation. + Lehrbuch der Pathol. Anat. Bd. ii. s. 195. pl. ix. fig. 1 & 2, and pl. xxii. fig. 3 & 4. ¢ Atti del Real Instit. d’Incoragg. alle Se. Nat Naples, tom. iii. p. 380, ~ 3a2 708 aa, the testicles ; bb, epididymes ; ec, vasa defe- rentia; dd, vesicule seminales. were not entirely complete, and there were superadded to them a female vagina and an imperfectly developed uterus, the Fallopian ‘ol of area mptomets the inguinal rings, and terminated with them upon the epididymes of the testicles. + tp sn Another instance of hermaphroditic malfor- mation in the goat, detailed at great length by Meckel,* seems also in its principal points justly referable to the present division of cases, although there was at the same time a tendency, in the unequal size of the two cornua uteri, &c., to a degree of lateral hermaphroditism. Professor Mayer, of Bonn,+ has detailed at length the dissection of three hermaphroditic Pi. hd Archiv fuer die Physiologie, Bd. xi. + Icones Select. Praparat. Mus, Anat. Bonn. p- 17-20, tab, iv, fig.5, and tab. v. figs. 1,2, & 3. HERMAPHRODITISM. goats, in all of which the conformation of the sexual parts resembled in its more essential por the preceding cases of Thomas and Gurlt. n all the three instances there were found two male testicles with their epididymes, vasa de- ferentia, and vesicule seminales; and at the same time there was present a well-marked female two-horned uterus, with a vagina open- ing into the urethra. In the first case the large hollow cornua uteri terminated in blind ex- tremities, and there were only very short im- ervious rudiments of the Fallopian tubes. n the second case, at the extremity of the right horn of the uterus, a blind appendicula was situated, formed by a vestige (according to Mayer) of the Fallopian tube; and from this a ligament was sent off to the correspond- ing testicle; a similar ligament, but no appen- dicula, existed on the left side. In the third case both Fallopian tubes were present, and each ended in a bursa formed by the lamina of the peritoneum, and partly surrounding the testicle and epididymes. In two of the in- stances the ejaculatory ducts seem to have opened into the urethra near the point at which the vagina terminated in it; and in one of the cases they opened into the canal of the vagina itself before it joined that of the urethra. All the external organs were male, but malformed in so far that the penis was short, and in two of the cases somewhat twisted; and the scrotum was either small or wanting. The same author* has described the dis- section of a dog, the sexual organs of which exhibited a similar variety of hermaphroditic malformation. The Fallopian tubes were per- vious throughout in this instance, and at their further extremities opened upon the neigh- bouring cellular tissue. The body of the two- horned uterus was very small, On compres- sing the epididymes and vasa deferentia, a fluid resembling semen issued from the openings of the latter into the urethra. The external sexual parts were those of a hypospadie male. Several cases of hermaphroditic malforma- tion in the human subject, similar in their anatomical characters to the preceding, have been described by Columbus, Harvey, Petit, Ackermann, and Mayer. a. In a person with external hypospadic male organs, Columbust found two bodies like testicles in the situation of the ovaries, and larger in size than the latter female organs na- turally are. From each of these testiform bodies two sets of tubes arose, one of which, like the male vasa deferentia, passed on to the root of the penis and opened into the urethra while the other, like the female Fallopian tubes, were inserted into an uterus. The prostate gland was absent. b. Harvey} has mentioned a very small her- maphroditic embryo, on which he found a two-horned uterus with two testicles of a very * Ib. p. 16. tab. iv. fig. 3, external parts of generation ; fig. 4, internal, t De Re Anat. lib, xv. ¢ De Gen. Anim, Exere, Ixix. p. 304. a ——E—E———————=— Se ee : 4 HERMAPHRODITISM. small size, and, near the diminutive penis, some traces of a tate gland. c. The observation of M. Petit,* of Namur, is still more complete. On the body of a sol- dier, aged twenty-two, who died of his wounds, and whose external organs ap to have presented no deviation from the male type except in the absence of the testicles from the scrotum, these bodies, with male vasa defe- rentia, vesicule seminales, and a prostate, were found to co-exist with female Fallopian tubes, and an uterus that was attached to the neck of the urinary bladder, and opened into the urethra between this neck and the prostate. The form of this imperfect uterus, M. Petit remarks, merited for it rather the name of a vagina than of an uterus, and it resembled more this organ in the female quadruped than in women. From the body of the uterus, at three inches from its entrance into the urethra, two Fallopian tubes arose. These tubes were rforated, and were three inches and a half ong; their abdominal extremities were not loose and provided with fimbrie, but were at- tached to a small soft hody on each side, occupying nearly the natural situation of the ovaries, but having the substance or structure of the testicles, and provided with an epidi- dymis and vas deferens. The vasa deferentia were each seven inches and a half long, and were attached to two long and rather slender vesicule seminales placed alongside of the uterus. The vesicule opened into the urethra by two ducts. Ina note appended to this case, M. Petit states that he had been consulted by a man who rendered blood by the penis regularly every month, without pain or any troublesome symptom. Perhaps, adds M. Petit, this man had also a concealed uterus. We have been informed, on credible authority, of two similar cases, the one in a young unmarried man of seventeen years of age, and the other in a per- son who had been married for several years without his wife having had any children. In both of these cases the discharge was in very considerable quantity, and perfectly regular in its monthly occurrence. Did it consist in a periodical hemorrhage from the urinary blad- der or passages only? or was it, as M. Petit Seems to suppose in his instance, of a true menstrual character, and produced by the re- productive organs of the female existing inter- nally, and communicating with the bladder or urethra ? d. Professor Ackermann,t of Jena, pub- lished in 1805 the following interesting case of the present variety of hermaphroditic malfor- mation. It occurred in an infant that lived about six weeks after birth. On dissection, two testicles were found; one of them had descended into the scrotum or labium; the other had advanced no further than the groin. Both were perfectly formed, and had their usual appendages complete. In the natural situa- * Hist. de l’Acad. Roy. des Sc. for 1720, p. 38. t Infantis androgyni ‘historia et icono phia, Edinb, Med, and Surg. Journ, vol. iii. p. 202. 709 tion of the female uterus, there was found a hollow pyriform organ, which, from its locality and connections, was supposed to be an ute- rus, though its coats were finer and thinner, and its cavity greater than naturally belongs to that viscus. Duplicatures of peritoneum, re- sembling the ligamenta lata, connected this im- rfect uterus with the sides of the pelvis, and its cavity opened into a kind of short vagina, which soon united with the urethra, and formed one common canal with it (vagina urethralis ). The vasa deferentia ran from the testicles towards the superior angles of the uterus, and penetrated into its substance at the points where the Fallopian tubes are usually placed. Without opening here, however, they passed onwards under the internal mucous-like mem- brane of the uterus and vagina, and at length terminated, by very small orifices, in the va- gina urethralis. Immediately previous to en- tering the ligamenta lata, each vas deferens formed a number of convolutions, conglome- rated into a mass resembling a vesicula semi- nalis. e. Steghlener* has described at great length the case of an infant that survived only for half an hour after birth, and upon whose body he found perfect external male organs (fig. 301, a 6), and internally two small elon- gated testicles (cc), with their epididymes (g g), the convolutions of their vasa deferentia (6 6) * De Hermaphr. Nat. p. 104. 710 distinctly marked. Between the rectum and bladder there was placed a very large pear- shaped bag or pouch (f'), with firm, coria- ceous, but not thick walls, and distended with fluid. This bag or imperfect cystoid uterus terminated inferiorly by a narrow neck, in a vagina that opened into the urethra, in the situ- ation of the verumontanum, and was_ there dilated into a large bag or ampulla, occupying exactly the site of the prostate gland, and re- sembling this organ also in its form and posi- tion. The internal membrane of the uterus was collected at its neck into numerous val- vular-like folds, and that of the vagina had also a rugous or plicated arrangement. From the fundus of the large sac of the uterus, and not from its angles, but from near its middle, two impervious solid ducts (Fallopian tubes, or rather vasa defcrentia,) arose, and after a somewhat flexuous course reached the testicle (cc) lying in the superior part of the iliac fosse. These ducts had attached to them at one or two points a number of small reddish nodules (6 b), consisting, according to Steghlener, of glandular granules, and described by Acker- mann in hiscase as vesicule seminales. The canal of the urethra was obliterated for a short distance towards the fossa navicularis, and the urinary bladder (j) and uterus (i i’) were ex- tremely distended, and the left kidney (a) was vesicular. Mayer, in the work already referred to,* has described and delineated the following five cases of the présent species of hermaphroditic malformation in the human subject, all of which he had himself met with and dissected. Ff. In a fetus of the fourth month, and affected with omphalocele and extroversion of the urinary bladder, he found male testicles (fig. 302, Fig. 302. aa) with their epididymes (b 6), and a two- horned uterus (c) terminating in a vagina (d), 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 tothe vagina; the right vas deferens (g) was shorter, * Icones Select. &c. p. 8-16. See also Walther and Graefe’s Journal der Chirurgie und Augen- heilkunde, Bd, vii. Hft. 3, and Bd, viii. Hit, 2. HERMAPHRODITISM. and became thread-like, and disappeared near the corresponding cornu of the uterus. seep tnd vasa deferentia, and vesicule semi- nales being present in all of them; and in Thomas's sheep the superadded female uterus shewed Ridaanalty the usual characteristic rugose structure, while its cornua terminated in two long Fallopian tubes. In Gurlt’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 ve 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- 0 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 o ation, 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 fetal 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 — part of the cavity of the trunk ese ies, as is now well known from the investigations of Rathke, Meckel, Miiller, 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 ae become, we have every reason to believe, occasionally permanent in one or more of its , 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, ! 731 the Wolffian body remains, for it 2a J ve 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 doubti whether, in some of the cases that we have cit of the supposed co-existence of testicles and ovaries upon the same sides, the unremoved 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 aj 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 oe observe that the consideration of the relative position occupied by the reputed testicles and ovaries bes oe, of afford us an useful guide in cases oubt. 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 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 visiblein 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 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, a 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. e 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 recise knowledge of the true anatomical pecu- iarities 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 preeputium 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 Medieal Repository, vol. xii. p. 86, HERMAPHRODITISM. fiable force. There is a tendency to the growth of a beard, which is kept short by clipping with scissors. The female parts do not differfrom 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 and 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- roduction, though perhaps unable, if we may judge from abortion having twice occurred, of ultimately perfecting that process. The preceding remarks upon the functional reproductive = of reputed true hermaph- rodites have been meant to apply only to the supposed perfection of one 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 fetuses on the opposite 5 or that mentioned by Faber (Hernandez? Nov. Plant. Anim. Mexic. Histor. p. 547) and quoted by Haller and Rudolphi, of the co-existence, in a rat, of ovaries and a uterus with nine foetuses, along with complete male organs. —— or , — “wr yr HERMAPHRODITISM. 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 the present date, for denying entirely and unconditionally the utter possibi- lity of it. And perhaps 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 quadrapeds. In one of the cases of hermaphroditism in the goat, previously quoted from Mayer, and where there were present two male testicles, epididymes, vasa deferentia, and vesicul 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 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 problematical remark : “ Puit ergo revera hermaphroditus semetipsum foecundare 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- i 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 =. 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 disc’ their seminal liquor into its own vagina. e imperfection the urethra most probably would have prevented the animal from ejecting a into the vagina of another indivi- ss P It has heen sometimes urged as an ment conclusively illustrative of the fact of a double hermaphrodite impregnating itself, that in the hermaphrodite Gastrophaga 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. 20. + Medical and Physical Researches, pp, 23, 24. ¢ Introd. ad Hist, Nat. p. 416. 733 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 Gastrophaga quercifolia, and in ano- ther in the Gastrophaga pint by Suckow.+ 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 Limneus auricularis§ and Helix vivipara|| among Mol- lusea, 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- Ts Skeo ws may, as we have just explained, 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 transito: 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 o 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 sof a neuter or yet undetermined sex which after- wards assume the structure of one or other of * Mém, de l’Acad. Roy. de Berlin, 1772. Lene Zeitschrift fir Organ. Phys. Bd, ii, s. ¢ Burmeister’s Entomology, s. 204. Burdach’s Physiologie, t.i. § 44, 4-8. Isis for 1817, p. 320. Spallanzani, Mém. sur la Resp. p. 268. Anat. Gén. t. i. p. 609. ** Hist. des Anomal. de l’Organiz, t. ii, 58. 734 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 Dugest have suggested that the variety of spurious hermaphroditism which consists of a division of the peri- nzum 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 fetus in utero are occasionally found morbidly distended with a fluid, which, according to the interesting observations of Dr. Robert Lee,t would appear to possess the more character- istic qualities of urine. We have dissected one case in which the dilated fetal 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 fetus 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. fiir Aertzte und Geburtsh, Bd, i. t. 264, 267. ; +t Ephem. Méd. de Montpellier, t. v. p. 17, 45, and 52. ¢ London Med,-Chirurg. Trans, vol. xix. HERMAPHRODITISM. pat of urine,* and in another detailed by Mr, ‘earn it was capable of containing as much as two quarts of fluid.t 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 the perineal 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 preternaturally dilated ureters, and a cystic form of the infundibula of the kidneys, as in a case of hermaphroditism given by Mayer, in a human feetus,{ 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 perinzal 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 tight 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 erin of eighteen years of age, which we ave 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- ee London Med, and Phys. Journ. vol. xxv. ps t+ Lancet for 1834-35, p. 178. . See p. 8, of Icones, &c. o Comment. Soc, Reg. Sc. Gotting. tom. i. p. 2. Icones, p. 12. a SS — ws se i i i i i ee | —— wees = -— HERMAPHRODITISM. dence, there is 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 ves in the meantime, for the Lom! oar drawing attention to the subject in the o - tion of any future similar instances that may pen to occur. n connection with the question of the causes of hermaphroditism, it is interesting to remark that in some instances malformations ¥ = genital ns giving rise to appearances of her- Beapbroditionn have been chau 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 Lecatt alleges that a degree of hypospadias is not uncommon among families in Nor- mandy. In Rust’s Magazine an instance is related of adegree of hypospadias existing in a father and son.t 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 Walrecht,|| and the second by Gockel.{ Sir Everard Home** found two cases of hypospadias in two children belonging to the same parents. Kauw Boerhaave}+ men- tions an example of four hypospadiac brothers, and Lepechin another instance of three.t{ Naegele has reported a case in which two male twins were hypospadic,§§ and Katsky ||l| and Saviard{/] 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. Beobacht. Bd. ii. s. 234, and Laroche sur les Monstrosités de la Face, p. 30. + Armand, 1. c. p. 312, S Menstin fuer die Gesammte Heilkunde, Bd. xviii, s. 113. Lee fissuris urethrz virilis fissuris congenitis, P* 1 Bardach’s Metamorph {_ Eph. Nat. Car. Dee. ii, Ann. 5. (1696), p. 85. ** Comp. Anat. iii. p. 320. ait Nov. Com. Acad, Se. Petropolit. t. i. p. 61. xi. Thid. t. xvi. p. 525. i Meckel’s Archiv. Bd. v. s. 136. des Geschlechter, p. M. Berol. Dec. 1, tom. ix, p. 61. { 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 were not unacquainted with the free-martin. Thus Columella de Re Raus- 735 ferent instances Mr. Hunter confirmed the fact of the anomalous sexual development of such animals by dissection; and Scarpa* and Gurlt} 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 fetal 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 speaksalso of having heard of some free-martins that were so perfectly formed in their sexual = as to be capable of breeding ; and different instances of their fe- cundity have been published by Dr. Moulson and otherst 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. We are not aware that among other uni- pee domestic animals, as the goat, mare, » 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 rejudice existing to a considerable degree pe the ieeert 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 “taure 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” (que 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, + 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. Leallen Med. Repos. vol, xx. p. 213, 736 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 ina 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 alae 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 serual 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. HERMAPHRODITISM. 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 sieaitionse 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, 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 cicatriculz upon this yolk, 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 develo ment, it appears more extraordinary that the sexes of the two conjoined fetuses should be so constantly uniform as they seem to be in monsters perfectly double. This uniformity only becomes the more singular when we re- fiect that twin children are not at all unfrequently of opposite sexes.§ * Nov. Comment. Acad. Petropolit. tom. xiv. p. 3 Meats Archiv. fiir Physiologie, &c. for 1827, Pp * +t We have in our possession a preparation, taken from a duck’s egg, in which two full-grown fetuses 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. Weknow of —- NERMAPHRODITISM. _ 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, and adduces three examples of it. In re-investigating this matter, the late Pro- fessor Meckel} 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 ris 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} and Lasenest;§ of double- headed monsters with single bodies, he quotes three similar cases from Lemery,|| Bacher,{ and Bilsius ;** and of monsters with a single head and double body he adduces two cases from Brisseust+ and Condamine,}{ 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 including and 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 t, non dari, sed unum tantum observari.”{ 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 oo In eleven out of these twelve pairs ¢ co-twins have been of opposite sexes. * Opuse. Anat, (1751,) p. 176. t De Duplicitate Monstrosa, p. 21. Eph. Nat. Cur. Dec. ii, Ann. iii. p. 190. Comment. Lit. Norimb. (1743,) p. 58. Mém. de l’Acad, des Se. de Paris, for 1724, Roux’ Jour. de Méd. (1788,) p. 483. ** Blankaart’s Coll. Med. &c. (1680. ) tt Six Observat. de M, Brisseau, (Paris, 1734,) p- 33, tt Mém. de l’Acad. des Sc. (1733,) p. 401. $$ Hist. des Anomal, de I’. iz. . iii. pp. oh an an mal, de ?Organiz. tom. iii. pp. Ib. p. 311, De Duplic. Monst. p, 21. VOL. II. 737 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 come it with Zeviani* and Lesauvage} 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.—A — (J.), De hermaphro- ditis, Venet. 1549. © » De re anatomica, lib. xv. Venet. 1559. Bauhin ( Gaspar), De her- maphroditorum monstrorumque partium natura. Francof. 1609. Schenkius (J. G.), Monstrorum historia memorabilis, Frankf. 1609. Riolan, Dis- cours sur les hermaphrodites, Paris, 1614. Zac- chias, Questiones medico-legales, lib. vii. Frankf. 1657. Palfyn, Licetus’ Traité des monstres. Leid. 1708. 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Osiander, Ueber die Geschlech wechselungen Neugeborner Kinder, in his Denkwurdigkeiten fiir Geburtshiilfe, Bd. II. s. 462. Gotting. 179. , and in the NeueDenkwurdigk, Bd. I. s. 245. Wri , De Singulari Deformitate Genitalium in puero Hermaphroditam 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 Mém. de la Soc. Méd. d’Emulat. tom. iv. p. 234. Paris, 1796, Moureau de la Sarthe, Quelques considerations sur 1l’hermaphrodisme, ibid. tom, i. p. 243; also in his Histoire Naturelle de la Femme, tom. i. p. 211. Paris, 1803. Pietsch, Gedanken von den Zwittern, in the old Hamburgh Magazin. Bd. IV. s. 538. Home (Ev. ), 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. IIL. Halle, 1805. Ackermann, Infantis androgyni hist. et iconog. Jena, 1805. : Von Unterschiede der beiden Geschlechter, in his Allgem. Gesichte des Lebens. Th. I. Leipz. 1806. Schneider, Der Hermaphroditismus, in Kopp’s Jahrb. der Staatsarzneikunde, p. 193, 1809, Meckel, Ueber die Zwitterbildung, in Reil’s Archiv fuer die Physiol. Bd. XI. Halle, 1812; Handb. der Pathol. Anat. Bd. Il. Leipz. 1816; System der Vergleich. Anatomie, Halle, 1821. Burdach, Metamorphose der Geschlechter, in Anatom, Un- tersuchungen, Leipzig, 1814; Physiologie, Bd. I. Leipzig, 1826. Metzger, Syst. der Gerichtl. Arz- neywiss. Konigsb. 1814. Marc, Bulletin des Se, Medicales, tom, viii. p. 179 & 245; Articles on her- maphrodites in the Diction. des Sciences Médicales, tom. xxi. p. 36-121, Paris, 1817; and Dict. de Médecine, tom. xi, p. 91, Ib. 1834. Steghlener, * Mem. della Soc. Italian. tom, ix. p. 521. + Mém. sur les Monstr. par Inclusion (Caen, 1829); or Archiv. Gén, de Méd. tom. xxv, p. 140, 3c 738 De hermaphroditorum Natura, Leipz. et 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, Berlin, 1818. Lawrence, Article Generation, in Rees’ Cyclopedia, 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 rétendus hermaphrodites, Mém. de l’Acad. de Tnrin, tom. x. Rudolphi, Beschreib. einer selt. Menschlichen Zwitterbildung, &c.; Abhand. der Konigl. Akad. der Wissens. zu Berlin fiir 1825. Berl. 1828. Lippi, Dissert. Anatomico-Zootomico- Fisiologiche, &c. Firenze, 1826. Dugés, Mém. sur l’hermaphrodisme, in Ephemerides Médicales de Montpellier, tom. i. Montp, 1827. Knox, Outline of a theory of hermaphrodism, in Brew- ster’s Edinburgh Journal of Science, vol. ii. p. 322. Edinb. 1830. Miiller, Bildungsgeschichte der Genitalien, Diisseldorf, 1830. Gurlt, Lehrb. der Patholog. Anat. der Haus-Saugthiere. Bd. IL. Berlin, 1831. Mayer, Icones Selecte preparat. Musei Anatom. Bonnensis; Decas Hermaphrodi- torum, p. 8. Bonn, 1831; and Walther’s and Graefe’s Journal, &c. Bd. XVII. Beatty, Article Donbtful Sex, in Cyclopadia of Practical Med. London, 1833. Beck, Medical Jurisprudence, chap. iv. p. 69-81, Doubtful Sex, London, 1836. Isidore St. Hiluire, Histoire des Anomalies de Vorganization, &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 uterusin 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 butfeeble. Hence hernie are most frequently met with at one of the places al- HERNIA. ready mentioned,—the umbilicus and the ingui- nal and femoral canals. But there are o 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 hernie. 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 epiplocele; or both these may be engaged, constituting the entero-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 arupture. 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 an Situation: the omentum is often dis pac: « particularly in inguinal herniz at the left side: the large intestines from being more fixed are not so frequently thrust out, yet the cecum and colon are but too often found among the con- tents of arupture. I have seen a large portion of the liver in an umbilical hernia of the infant: Verdier+ relates numerous cases of hernie of the urinary bladder; and Pott{ 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 sigmoid flexure of the colon has been protruded at the right side, and the ceecum and valve of the ileum at the left. In all large and old herniz the parts are dragged out of their proper situations, * Sur plusieurs hernies singuliéres. Garengeot, Mémoires de l’Academie Royale de Chir. tom. iii, p- 336, Paris edit. in 15 vols. 1771. + Mém. de l’Acad. Royale de Chir. tom, iv. p. 1. $ Pott’s Works, by Earle, vol. ii. p. 210. HERNIA. and their appearances on dissection and rela- tive positions are ofien such as no one from anatomical knowledge alone could ever have ot ag to be possible. n 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 sac, which is eased 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 behite 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 yrs and contractility.” * Man surgeons have doubted the ibility of ak an occurrence at an peasy bat 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 hernie 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 vente is never completely oblite- rated, it is palpab y diminished in size, and in- le of receiving and retaining the same quantity of contents it originally held. Some- times in old and neglected hernie the sac seems to become so thin that the peristaltic motion of the intestines within it ae been clearly ived: 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 hernia also, and particularly where bandages have been worn to support or compress the tumour, it seems to become very thick, strong, and tense, and is said to have keen 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 doubtless 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 by Wishart, p. 68. + See Louis, Mém. de l’Acad. Roy. de Chir, _ tom. ii. p. 486. 739 some writers have supposed. It was the opinion of 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 froma 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 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- siovally suffering from inflammation, and hence adhesions between it and the sac are by no means unfrequently formed: the same effect may be eri! 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 ritoneum. 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 cireumstances. 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 repent 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 a truss, the neck gradually contracts under the pressure, anc its 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 3c2 740 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 fetal 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 the peritoneum, but preserving its 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,+ 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 aban 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 (iconomy. + See 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. B56. ITERNIA. and the hernia congenita is formed, If any part of the above-mentioned process is interrupte 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 thedescent of a hernia: sometimes the testicle does not come down until a much later period, a circumstance that is often occa- ileal 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. Scarpat 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 ee closed ; but with respect to congenital hernia the observa- tion appears to be equally correct and im- portant. Scarpat describes a form of hernia which may * Pott, op. citat. p. 184. + Page 131. ¢ Op. citat. p. 205 et seq. ILERNIA. under certain circumstances of imperfect or care- Jess examination og wo 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 cecum with the appendix vermiformis and the begin- ning of the colon. The cecum is placed in the right ileo-lumbar region, and a portion of it does not $a peritoneal covering, but lies abso- lutely without the great abdominal membranous sac: when therefore these parts are protruded, a portion of the cecum 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 peepee 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 cecum and colon will be exposed lying outside of the peritoneum, and ap- ntly devoid of a hernmial sac; but if cut into precisely in the middle or a little towards the inner side, under the cremaster 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 cecum 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 hernia, 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- laced without difficulty to the operator or ture inconvenience to the patient beyond that resulting from the employment of measures ada 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 Raed 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- iment. There is another case in which a ia 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 tered as not only to prevent reduction, but 74l 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; 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- icion is increased if the tumour is elastic, if it sounds clearly on gentle percussion, and becomes seiddeisty 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 rediueliste 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 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, Mém. del’ Acad. Roy. de Chir. tom, ii. p. 382. + Op. cit. p. 290. 742 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 eb 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. Ina 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. HERNIA. 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 sgcrpc amish 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 usuall left down. On asudden he was attacked wi symptoms of strangulation, small quick pulse, tenderness of the abdomen, acute pain in the tumour, constipation, general low fever and feecal 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 Pott} as one peculiarly difficult of reduc- tion. “They have consisted of the cecum 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. + Pott, op. cit. p, 24. HERNIA. have seen and dissected a case of this deserip- 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 —— 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 hernia 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 the trunk or inferior extre- mity might possibly diminish its size, no mus- cular dcsion 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.+ Guthrie speaks of hernie being frequeutly strangulated by passing between the fibres of the internal oblique, which are separated at the inferior and external border of the muscle above * See the anatomy of inguinal and femoral hernia in a future part of this article, + Cooper on Hernia, p. 21, 743 the origin of the cremaster.* 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:”+ 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 s tic cord ; it then extends and on 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 hernie are liable to a spasmodic constriction, or with the descriptive anatomy on which such an opinion might be founded. n 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 may be stretched also, and the epigastric artery pulled out of its lace and made to approach the linea alba; ut 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 ; the 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 - * Guthrie. + Scarpa, op. cit. p. 27. } Ibid’ p. 0. 744 gerous, because the existence of strangulation with all its fearful sequela 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 which abdominal hernie 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 which 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, ifa 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 HERNIA. incapable of return, and explain why such her- nie 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 coutents 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- niz 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 hernie into the incarcerated and strangulated, or into the acute and chroni¢ forms of strangulation, however practically valuable if it inculeates 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 herniz the neck of the sae 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. Ifsuch 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- * Mém. de l’Acad. Roy. de Chir. tom. viii. p. 40. HERNIA. 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. e 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 re degree of intensity. A hernia has been gan- a in eight hours after protrusion. Mr. ‘ott 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 a decided, although every moment of its uration 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 al increased. In small hernie (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 a'most every other Species : in most cases it is produced by an 1 quantity of blood sent by the arteries of the part, which 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 of its colour from the arterial to the venous hue.” Cooper on Hernia, p. 20, 745 brown, and there is always more or less of sernm 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 feces and horribly fetid gas. is 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, edematous, 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 oneor 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 any 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 but a far more serious because a more fatal rocess is going forward within the abdomen. t 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 anum 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 feeces, inflammation is established within the cavity, commencing probably at the strictured spot, and spreading thence with great rapidity. e 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 NERNIA, 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 space 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. J 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. and as complete in omental as in intestinal ruptures. Ata 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 € 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 fecal 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 hernie were formed of loo 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 yery peculiar character: strictly speaking, it is not vomiting or retching, nor is it biceup, but a slight convulsive effort like a gulp, which brings up without much effort the quantity of asingle mouthful at atime. 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 variable) the characters of the disease lines 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 feces. This evacuation leads the patient into the ty ag 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 ch 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 Hip tica.” The eye has 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 TAT 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 long 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 ritoneal 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 roceeded to gangrene and the patient. still liven, 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 enue 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 of an artificial anus being formed, the patient and the hernia must be placed under cireum~- 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 itis 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 he 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. Mém. de l’Acad. Roy. v, 8. HERNIA. 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 herniz, 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 haying 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, asit 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 précédent la destruction des parties, et elles previennent le plus souvent l’epanchement des matiéres dans le ventre.””—Dupuytren, Legons Orales, tom. ii. p. 197, — vo HERNIA. 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 gi 9 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 , 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 ischarged 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 ible 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 ina sufficient state of distension. The ore 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. 749 when he could find it, as if to preclude for ever a possibility of the continuity of the tube being restored. is is a most deplorable condition, yet have patients endured the annoyance of a erage discharge at the groin for a great ength 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 isa 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 feces 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 oe by some ingenious contrivance, abso- utely 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. Now 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 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 death that could not have proved unwelcome. In a vast number of cases the projection is not so great, andalthough it may impede and delay, it does not altogether prevent the passage of faces 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 feces 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 lowala: 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, anda fecal 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 fistuious 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 1s 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 contractedwith the neck of the sac, whether this is caused by the tonic * Scarpa, op. citat. p. 313. HERNIA. 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 herniz not gangrenous, but merely complicated with fleshy adhesions to the neck of the sac, and therefore irreducible. In these herniz, 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, r 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 * Legons Orales, tom. ii. p. 207. HERNIA. process of the ilium. As these are but different Stages of the same disease, both come under the uppellation of hernia by the oblique descent. ut, 3, when the viscus has n 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- Tal 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 as being divided into two great depressions at each side, the medium of partition being the ane into which the umbilical artery of the foetus had degenerated, together with the fold of peritoneum raised by that ligament. Of these fosse 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 herni, re, by the oblique descent pass out from the aor § 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 im 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 io 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 re most disposed to permit of the oecur- “rence of hernia. In prosecuting the dissection from within ove is by far the most satisfactory manner), peritoneum — 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 fangs cece of ths aemaleen? teow ate tis mbdrane the dead body, on a hoop like a datas eae foant it capable of supporting a weight of fifte ishing wptuek-2 se 751 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 iliaea, 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 u wards. It then appears in front, between r 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 d 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 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. hen a protruded viscus, then, is passing 752 through this ring, it has 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 yas 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, icularly 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 anarched 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,t the upper part only of the internal ring is shut up by these muscles, leaying 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. Cloquet} 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. + Lawrence on Ruptures, p. 162. t Anatomy of Hernia, by Jules Cloquet, trans- lated by M’Whinnie, p. 6. HERNIA. covers the spermatic cord in the inguinal canal, and passes over it to be inserted into the pubis at the point where if escapes from the eerie opening of the canal, that is, the external rmg. 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 Guthrie+ considers the occasional passage of a hernia through the fibres of this muscle, and its compression by them, to be no unfrequent 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 ABpoMEN. 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.t Independent of these adventitious bands the tendon itself, as itapproaches 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. + Anatomy of Hernia. ¢ Sometimes termed Camper’s fascia, from its being so admirably delineated in the ‘* Icones.” ee ee Oe td eS, eye HERNIA. -éferior 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 # quarter in length, the base of which, nearly half an inch across, is situated at the pubis, from which it tapers gradually off ina direction _ upwards and outwards. Fora 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 sti]l 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. Tn 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 in 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. Atthe groin it is usually well developed, and is described as consisting of two distinct Jamine, but may (by such as are curious in these ve coe ager ag care be separated into many more.+ @ superficial layer is ve Jax, 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 —~ is more membranous, and possesses more of the determined character of a fascia. It adheres intimately to the muscular fibres of the external eblique, passes thence inwards over the tendon, 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, &e. It is to be re- gretted that such a confusion of i ob- tains in the description of these parts,—a confusion always emb ig to the stud and rendering the subj 1 2 Lo lexing and difficult. + Velpeau describes three distinct layers, Ana- tomie des Regions, tom, ii. p. 70. VOL. II. 753 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 laminze. 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 pape n herniz 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 oecasioned by the growth of the hernia, and the compression exer- cised by it on the cellular substance connecting the constituent 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 sae 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 @ 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 ou large and old hernie. Perhaps the next point ef 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 are generally described as iying between the layers of the superficial fascia, n dissection, this has not appeared to me to be the case. 3p 754 hernia just described may exist in two different conditions ; one, in which 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 "atte of life, and an enlarged inguinal gland. lowever 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 le in the fold of the groin, but an enlargement, whether from a venereal or any other cause, of two lymphatic glands which lie 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. HERNIA: 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 poe 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. 4 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. + Scarpa, op. citat. p. 235, 7s ——eee active treatment was adopt HERNIA. He 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 pediad up, but re-a 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 cadeabed :