KING'S College LONDON ^nrQ Qr\ Tap ^ Library Digitized by the Internet Archive i in 2015 https://archive.org/details/b2130046x_0004 THE CYCLOPAEDIA OF ANATOMY AND PHYSIOLOGY. VOL. IV. London ; Spottiswoodes and Shaw, New-Street-Square. THE CYCLOPEDIA OF ANATOMY AND PHYSIOLOGY. EDITED BY EGBERT B. TODD, M.D. F.R.S. FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS; PHYSICIAN TO king's COLLEGE HOSPITAL; AND PROFESSOR OF PHYSIOLOGY AND OF GENERAL AND MORBID ANATOMY IN KING's COLLEGE, LONDON, ETC. ETC. VOL. IV. P L A W R I LONDON: LONGMAN, BROWN, GREEN, AND LONGMANS. 1852. CONTRIBUTORS. JOHN ADAMS, Esq. Surgeon to the London Hospital, and Le;:turer on Anatomy. ROBERT ADAMS, Esq. Surgeon to the Richmond Hospital, and Lecturer on Anatomy and Surgery, Dublin. B. ALCOCK, M.B. Dublin. W. P. ALISON, M.D. F.R.S.E. Prof, of the Pract. of Med. in the Univ. of Edin. &c. JOHN ANDERSON, Esq. M.E.S. Richmond. J. APJOHN, M.D. M.R.I. A. Prof, of Chem. to the Royal Coll. of Surgeons, Ireland, VICTOR AUDOUIN, M.D. Paris. Professeur-Administrateur auMusee d'HistoireNaturelle. B. G. BABINGTON, M.D. F.R.S. Physician to Guy's Hospital. THOMAS BELL, Sec. R.S. Professor of Zoology in King's College, London. CHARLES BENSON, M.D. M.R.LA. Prof, of Med. to the Royal Coll. of Surgeons, Ireland. J. BISHOP, F.R.S. London. JOHN BOSTOCK, M.D. V.P.R.S, London. W. BOWMAN, F.R.S. Assistant- Surgeon to the King's College Hospital and to the Royal Ophthalmic Hospital, Moorfields, and Professor of Physiology, King's College, London. J. E. BOWMAN, Esq. Prof, of Practical Chemistry in King's Coll. London. W. T. BRANDE, F.R.S. Professor of Chemistry to the Royal Institution, &c. J. E. BRENAN, M.D. (the late). W. BRINTON, M.D. Medical Tutor in King's College, London. W. B. CARPENTER, M.D. F.R.S. Prof, of Med. .Jurisjirudence, Univ. Coll. Lond. JOHN COLDSTREAM, M.D. Fell Roy. Coll. Phys. Edinb. &-c. W. WHITE COOPER, F.R.C.S. Sen. Surgeon to the North London Eye Infirmary, Ophthalmic Surgeon to St. Mary's Hospital. DAVID CRAIGIE, M.D. F.R.S.E. Fellow of the Roj'al Coll. of Physicians, Edinb, &:c. T. BLIZARD CURLING, F.R.S. Lect. on Surg, and Surg, to the Lond. Hospital. G. P. DESHAYES, M.D. Paris. A. T. S. DODD, Esq. (the late). I. DRUMMOND, M. D. Edinburgh. P. M DUNCAN, M.D. Physician to the Infirmary, Colchester. H. DUTROCHET, M.D. W. F. EDWARDS, M.D. F.R.S. (the late). H. MILNE EDWARDS, M.D. Prof, of Nat. History to the College of Henry IV., and to the Central School of Arts and Manufactures, Paris. ARTHUR FARRE, M.D. F.R.S. Professor of Midwifery in King's College, and Physi- cian Accoucheur to King's College Hospital. HEINRTCH FREY, M.D. Prof, of Gen. and Comp. Anat. at Zurich, R. D. GRAINGER, F.R.S. Lect. on Anat. and Phys. at St. Thomas's Hospital. R. E. GRANT, M.D. F.R.S. L. & E. Fell, of the Roy. Coll. of Physicians, Edinb. and Prof, of Comp. Anatomv and Zoology in Univ. College, &c. W A. GUY, M.D. Prof. For. Med. King's College, London, and Phy. sician to King's College Hospital. M. HALL, M.D. F.R.S. L. & E. London. HENRY HANCOCK, Esq. Lect. on Surgery at, and Surgeon to, the Charing- Cross Hospital. ROBERT HARRISON, M.D. M.R.LA. Prof, of Anat. and Surg, in the Univ. of Dublin. JOHN HART, M.D. M R.LA. Prof, of Anat. in the Royal Coll. of Surg. Dublin. A. HIGGINSON, Esq. Liverpool. J. HUTCHINSON, M.D., London. ARTHUR JACOB, M.D. M.R.LA. Professor of Anatomy and Physiology to the Royal College of Surgeons in Ireland. GEORGE JOHNSON, M D. Assistant Physician to King's Col. Hosp. Lond. C. HANDFIELD JONES, M.D. F.R.S. Physician to St. Mary's Hospital, London. T. RUPERT JONES, E.sq. Assistant Sec. Geolog. Soc. London. T. RYMER JONES, F.R.S. Prof, of Comp. Anat. in King's College, London. T. WHARTON JONES, F.R.S. London. W. SENHOUSE KIRKES, M.D. SAMUEL LANE, Esq. Lecturer on Anatomy, St. George's Hospital, London EDWIN LANKESTER, M.D. F.R.S. Lecturer on Materia M(!dica and Botany. J. LEUCKARDT, M.D. Gottingen. A. KOLLIKER, Prof, of Anat. and Phys. in the Univ. of Wurzbnrg. F. T. MACDOUGALL, Esq. BENJ. M'DOWEL, M.D. Lecturer on Anatomy at the Richmond Hospital, and Physician to the Wliitworth Hospital, Dublin. JOSEPH MACLISE, Esq., London. JOHN MALYN, Esq. (the late). vi CONTRIBUTORS. ROBERT MAYNE, M.D. Lect. on Anat. & Phys. Richmond Hospital, Dublin. W. A. MILLER, M.D. F.R.S. Professor of Chemistry in King's College, London. W. F. MONTGOMERY, M.D. M.R.LA. Fellow of, and Professor of Midwifery to, the King and Queen's College of Physicians in Ireland. GEORGE NEWPORT, F.R.S. F.L.S. R. OWEN, F.R.S. F.G.S. Hunterian Professor of Comparative Anatomy and Physiology to the Royal College of Surgeons, London. JAMES PAGET, F.R.S. Lect. on Anat. &Phys. St. Bartholomew's Hospital. " RICHARD PARTRIDGE, F.R.S. Prof, of Descrip. and Surg. Anat. King's College. Surgeon to King's College Hospital, London. BENJAMIN PHILLIPS, F.R.S. London. Surgeon to the Westminster Hospital. SIMON ROOD PITTARD, Esq. Associate of King's College, London. W. H. PORTER, Esq. Prof, of Surgery to the Royal Coll. of Surg, in Ireland. G. OWEN REES, M.D. F.R.S. Assistant Physician to Guy's Hospital. J. REID, M.D. (the late). Prof, of Medicine in the University of St. Andrews. EDWARD RIGBY, M.D. F.L.S. Lect. on Midwifery at St, Bartholomew's Hospital. J. FORBES ROYLE, M.D. F.R.S. F.G.S. Prof, of Materia Medica in King's College, London, H. HYDE SALTER, M.D.^ Demonstrator of Anatomy in King's Coll., Lond. S. JAMES A. SALTER, M.B., London. HENRY SEARLE, Esq. London. W. SHARPEY, M.D. F.R.S. Prof, of Anat. and Physiol, in Univ. Coll. London, JOHN SIMON, F.R.S. Surgeon to and Lect. on Path. St. Thomas's Hosp. J. Y. SIMPSON, M.D. Fellow of the Royal College of Physicians, and Pro- fessor of Midwifery in the University of Edinburgh. SAMUEL SOLLY, F.R.S. Surgeon to St. Thomas's Hospital. GABRIEL STOKES, M.D. J. A. SYMONDS, M.D. Physician to the Bristol General Hospital. ALLEN THOMSON, M.D. F.R.S. Prof, of Anatomy in the University of Glasgow. JOHN TOMES, Esq. F. R. S. Surgeon-Dentist to the Middlesex Hospital. WM. TREW, Esq. W. VROLIK, Prof. Anat. and Phys. at the Athenaeum of Amsterdam RUDOLPH WAGNER, M.D. Prof, of Anat. and Phvs. in the Roy.Unlv. Gottingen W. H. WALSHE, M.D. Prof. Med. Univ. Coll. London, Physician to Uni- versity College Hospital, &c. N. WARD, Esq. Demonstrator of Anatomy, and Assistant Surgeon to the London Hospital. R. WILLIS, ]\LD. ' W. J. ERASMUS WILSON, F.R.S. Consulting Surgeon to the St. Pancras Infirmary. J. WOOD, Esq. Demonstrator of Anatomy in King's Coll., Lond. CONTENTS OF THE FOURTH VOLUME. Page Pleura aS'. R. Pittard, Esq. 1 Polygastria Professor R. Jones 2 Polypifera Professor B. Jones 18 Popliteal Region ... W. Trew, Esq. ... 60 Porifera Professor R. Jones 64 Products, Adventitious Dr. Wahhe 71 Prostate J. Adams, Esq. ... 146 Protein Prof. J. E. Bowman 162 Pteropoda Professor B. Jones 170 Pulse Dr. Guy 181 Quadrumana '.. Professor Vrolik ... 194 Radial Artery Dr. Brinton 221 Radio-ulnar Articu-") -r, „ • . \Dr. Brinton 228 lation J Ren Dr. Johnson 231 Reptilia Professor R. Jones 264 Respiration Dr. John Reid ... 325 Rodentia Professor R. Jones 368 Rotifera Dr. Lankester 396 Saliva Dr. Owen Rees ... 415 Salivary Glands N. Ward, Esq. ... 422 Scapular Region ... Dr. M' Dowel 433 Scrotum Dr. Brinton 438 Secretion Dr. Carpenter 439 Semen -T ^cig^^^ and 1 ^ ^ L Leuckhardt j Sensation Dr. Todd 508 Sensibility Dr. Todd 510 ^Dr. Brinton 511 Sesamoid Bones S. R. Pittard, Esq. 541 Seventh Pair of Nerves i>r. Brinton 543 Shell Dr. Carpenter 556 Shoulder Joint (Nor- mal Anatomy) J Shoulder Joint (Ab--| „ , ^ r^ j-x- > Robert Adams, Esq. 577 normal Conditions of) J ' ^ Sixth Pair of Nerves Dr. Brinton 621 Skeleton Joseph Maclise, Esq. 622 Sleep Dr. Carpenter 677 Smell Dr. Carpenter 697 Softening and Indu-T ration j Dr. P. M. Duncan 703 Page Serous and Synovial Membranes Dr. M' Dowel 571 Solipeds Professor R. Jones 713 Spinal Accessory. Nerve J Spinal Nerves N. Ward, Esq 750 Spleen Professor KoUiker 771 Statistics, Medical ... Dr. Guy 801 Subclavian Arteries Dr. M'Dowel 814 Supra-renal Capsules Prof Heinrich Frey 827 Sweat Dr. G. O. Rees ... 841 Symmetry aS'. R. Pittard, Esq. 845 Sympathy Dr. Todd 852 Synovia Dr. G. O. Rees ... 856 Taste Dr. Carpenter 856 Teeth Professor Owen ... 864 Temperament Dr. Todd 935 Temporo - maxillary 1 _ _ Articulations \ S. S. Pittard, Esj. 937 Teratology Professor Vrolik ... 942 Testicle T. B. Curling, Esq. 976 Thorax Dr. Hutchinson 1016 Thymus Gland Dr. Handf eld Jones 1087 Thyroid Gland Dr. Handfield Jones 1102 Tibio-fibular Articu- ■) lations jDr.M^Dowel 1118 Tongue Dr. Hyde Salter ... 1 1 20 Touch Dr. Carpenter 1163 Tunicata Professor R. Jones 1185 Urethra John Adams, Esq. 1244 Urine Dr. G. Owen Rees 1268 Varieties of Mankind Z>r. Carpenter 1294 Vein S.Jas. A.Salter, Esq.1367 Venous System Dr. M 'Dowel 1403 Vesicula Prostatica... Professor Leuckhardt 14:15 Vesiculse Seminales S. R. Pittard, Esq. 1429 Vision I ^^'""^^ (hooper, 1 ^^^^ L Esq. J Vital Statistics Dr. Guy 1459 Voice John Bishop, Esq. 1475 Wrist Joint (Normal Anatomy, Wrist Joint (Abnor- Anatomy j^'' ^'-""^'^^ rist Joint (Abnor- "1 ^ 1 /-I j-x- „^ \ R' Adams. Esq. ...1508 mal Conditions of ) J ^ THE CYCLOPEDIA ANATOMY AND PHYSIOLOGY PLEURA is tbe name given to the serous sac of the lung and the cavity containing it. There are two pleural sacs, one for the right lung and right side of the thorax, the other for the left lung and left side of the thorax. These tvvo sacs being apposed and adherent to one another in the middle line, form there a median, antero-posterior, vertical septum, called the me- diastinum, which divides the thoracic cavity into two lateral compartments. Each pleura is, like all other serous membranes, with one exception, a shut sac ; and there being but one organ contained in each pleural cavity, and that organ being of a tolerably simple form, the well-known comparison of a double nightcap, expressive of the manner in which a serous sac lines the interior of a cavity and invests the exterior of the viscus contained in it, is ex- tremely apt in the case of these sacs lining the chest and covering the lungs. Of the two sur- faces of the sacs, the inner one is everywhere free and the outer everywhere adherent ; such in fact is universally the case with all serous membranes. Each pleura invests its respective lung, and lines the moiety of the thoracic cavity to which it belongs, in the simplest manner pos- sible, as simply and accurately as though it were a coating of paint, dipping into the fissures of the lungs and into the acute angles formed by the costse with the arching diaphragm in the most neat and accurate manner. It only remains then, in order to complete our descrip- tion of the course of these membranes, to ex- amine the manner in which they pass from the parietes to the viscus. It is thus:— the two pleurae, above, below, behind, and in front, meet one another in or near the middle line, VOL. IV. and form the mediastinum above-mentioned ; between the layers of the mediastinum are situated the heart and great vessels and the termination of the trachea; from these issue on each side a bronchus, pulmonary artery, pul- monary veins, &c. destined to the lung, which, bound loosely together by areolar tissue, have received the appellation of the root of the lung; this root of the lung emerges from the media- stmum at about the middle of its posterior upper quarter, and is covered with a layer of the pleura, which thereby becomes conducted from this point of the mediastinum to the lung. The term mediastinum is applied by some writers to the antero-posterim- vertical septum of the chest, by others to the spaces occupied by the viscera situated between its layers ; in the latter senseof the term three mediastinaare enumerated — anterior, posterior, and middle ; the anterior, which is very large, is the space occupied by the heart in its pericardium, thymus gland, or its re- mains, and phrenic nerves ; the middle contajns the bifurcation of the trachea, the arch of the aorta, the pulmonary and other great vessels ; the posterior contains the aorta, oesophagus, &c. All these organs, their position, &c. will be found described in other parts of. this work ; their right and left aspects are invested by the right or left pleura respectively. It is in their larger interspaces only that the two pleuroe come into actual contact and adhesion with one another. The smaller interspaces are not intruded upon by the pleurae, but are occupied with areolar tissue and fat. In most of the lower (mammalian) animals, where the chest is deep and narrow, and in the human foetus, the tvvo pleurae come into adhesion with one ano- 2 POLYGASTRIA. ther in front of the heart ; but in the adult human subject this is not the case, the pericar- dium coming into immediate contact with the anterior thoracic parietes. Also the pleurae are prevented by the adhesion of the pericardium to the diaphragm from adhering to one another below the heart. It is almost superfluous to state that the heart and pericardium encroach more upon the left pleural cavity than upon the right. The median thoracic septum of the hu- man subject is able, partly on account of its small antero-posterior extent, to resist any con- siderable lateral displacement, such as might result from accumulation of effusion into one pleural cavity ; but in deep- chested animals it admits of displacement to such an extent that the whole of the chest may be filled with an effusion into one pleural cavity. In a Chetah, which died of pleurisy at the gardens of the Zoological Society, dissected by the author, the immediate cause of death was suffocation occa- sioned by effusion into the right pleura, which, occupied the whole chest, and compressed the left lung, the left pleura being unaffected. The mediastinum may be regarded as a kind of mesentery to the heart, and in some reptiles it is very obviously seen to be a part of the great median mesentery wherein all the viscera are suspended. This great median mesentery of reptiles is attached to parietes in front as well as behind as far down as the falciform liga- ment of the liver; as though a fold of serous membrane had been pulled down by the umbi- lical vein. In some reptiles, as the chame- leon, the anterior parietal attachment is conti- nued even down to the small intestines, so that the stomach and part of the small intestine are enclosed between the layers of the mediasti- num. The serial homology of this septum is ob- scured in Mammalia by the diaphragm being interposed between it and the other mesenteries. The only fold or duplicature made by each pleura that is comparable to the mesenteries or omenta formed by the peritoneum is that called the broad ligament of the lung (ligainentum latum pulmonis ). It is a fold carried down- wards and backwards from the root of the lung. It may be described as having four edges, the upper one of which is attached along the lower aspect of the root of the lung; the outer one is attached to the inner aspect of the lung from its root to its lower border; the inner one is attached to the mediastinum from the root of the lung downwards and backwards to the oesophageal opening in the diaphragm ; the remaining edge is free and directed outwards, downwards, and backwards. Its inner or mediastinal attachment is by far the longest, so that its figure is four-sided, with one corner extremely drawn out or prolonged. There are frequently found, especially about the pericardium, numerous pyriform masses of fat covered with pleura, like appendices epiploicae. The outer surface of the pleura is but loosely adherent to the ribs and intercostal muscles; it is more firmly connected with the diaphragm and pericardium, and still more firmly with the lungs. The adhesion of the two pleurae in the mediastinum is extremely loose in the human subject, large quantities of areolar tissue and frequently fat being interposed ; so that in many subjects they can hardly be said to come into immediate contact at all. The pleura covering the ribs and that forming the mediastinum is strengthened by a fibrous layer, but that covering the lungs is destitute of such fibres, and consequently extremely thin and delicate. The terms pleura pulmonalisy pleura costalis, and pleura diaphragmatic a, are applied respectively to those parts of the pleurae which are connected with the lungs, the ribs, and the diaphragm : and these expressions are frequently found extremely convenient. From the extreme frequency of abnormal adhesions of the apposed surfaces of the pleura it appears that this serous membrane is un- usually liable to inflammation, which liability may be due to its being unusually exposed to external circumstances through its extreme proximity to the air in the lungs. The pleura is peculiar to the class Mammalia. In Birds the lungs are adherent to the thoracic parietes ; and in Reptiles, there being no dis- tinction of thorax and abdomen, they are in- vested by the peritoneum. To this, however, there is an exception in the Crocodilians, in which reptiles a rudimentary diaphragm exists. The pleurae of these animals are disposed around the outer, anterior, and posterior, but not the inner aspect of each lung ; so that the lung seems to be adherent to the mediastinum. (Simon Rood Pittard.) POLYGASTRIA. — A name applied by Professor Ehrenberg, of Berlin, to an immense class of microscopic animalcules which exist in countless millions in water of various kinds, both salt and fresh, more especially m such as contains decomposing animal or vegetable substances. Many forms of these beings are indescribably minute, some of them measuring not more than the 32,000th part of an inch in length, and all of them are of such tiny dimensions as to require the utmost penetration of the micro- scope and the most patient industry on the part of the observer to make out their organization. A few of the largest are, indeed, barely distin- guishable by the unassisted eye; but, generally speaking, they are quite invisible ; and had it not been for the invention of the microscope, we should, even at this day, have been ignorant of their existence. The numbers in which these creatures abound baffles all expression. It has been ascertained, and the fact may easily be proved with a good microscope, that, possessing the dimensions above referred to, say the 24,000th part of an inch, many of these living atoms crowd the water in which they are found to such an extent that they are not separated from each other by a space greater than the size of their whole bodies; so that by a very little calculation it will be seen that a single drop of such water contains more of these active existences than there are human beings upon the surface of this globe. And when the mind reflects upon their POLYGASTRIA. 3 universal distribution wherever water is to be met with fit for their reception, it is impos- sible not to be overwhelmed with the con- templation of a scene so calculated to impress upon us the infinitude of the works of the Creator. Our knowledge of the class of animals under consideration dates from a very recent period. The earliest observers with the microscope, partly from the imperfection of their instru- ments, and partly from ignorance of any cha- racteristic distinctions, were in the habit of grouping all the creatures of microscopic dimensions, which they perceived swimming in the water they examined, as belonging to the same category, under the name of " Infusorial Animalcules," a title which consequently em- braced creatures of the most dissimilar forms and habits, and even widely removed from each other in the scale of animal existences by their internal organization and general economy ; thus the Rotifera, the larvae of insects, the gemmules of Polyps, and innumerable other minute creatures were confounded under the same denomination. It is to the researches of Ehrenberg, the great historiographer of these beings, that we are indebted for the breaking up of this chaotic assemblage, and the introduction of order where all was previously confusion and uncertainty. Prior to his discoveries naturalists denied the existence of any alimentary apparatus in the Infusoria, believing them to be nourished by a kind of imbibition, and regarding the granular bodies contained within them as being their eggs or young ones. Ehrenberg, however, by placing indigo, carmine, sap-green, and similar extremely pure coloured vegetable sub- stances in the water containing them, soon found that the coloured material was readily admitted into the interior of the body, and there disposed in such a manner as to convince him that there were numerous receptacles in the interior of these little beings, which he con- sidered as forming their nutritive apparatus ; and having applied to them the name of stomachs, he was induced to establish a distinct class for creatures thus organised, and distinguished them from all other animals by the name of POLYGASTRIA.* These stomachs he subsequently discovered to be variously arranged in different genera, and was consequently induced to make these variations in the construction of the alimen- tary apparatus a basis on which to erect a scheme for their further subdivision. This kind of nutritive system of organs he found presented itself under different forms ; in some species the stomachal cavities communicate separately with the oral orifice, so that there is no intestinal tube or passage of intercom- munication between them : to such he has applied the term ANENXERA.f In all others there is a wide intestinal tube in the interior of the body, to the sides of which the numerous alimentary vesicles or reservoirs are appended, * woXu?, many ; yaa-riif, a stomach. + a, priv. ; ivTspov, intestine. terminating by an anal orifice : these have been named from this circumstance Enierodela.* The Enterodelous Polygastria are again divi- sible : — 1st. Into those in which the intestinal tube is disposed in a circular form in the interior of the body of the animalcule, winding round so that the mouth and anus are contiguous. (CYCLOCGELA.f) 2nd. Into those in which the intestine tra- verses the body of the animalcule, passing along its longitudinal axis, and presenting two orifices completely distinct and opposite to each other ; that which is anterior forming the mouth, the posterior the anus: such are characterized as Ortuoccela.J 3rd. Such as have a winding or twisted intestine, which never passes in a direct line through the long axis of the body : these genera are named Campyloccela.§ Such a classification, founded entirely on the anatomical arrangement of one set of organs, Ehrenberg acknowledges would be quite con- trary to the established rules of zoology, were it not that the external characters of these animalcules are most exactly conformable with the structure of the alimentary canal ; but find- ing that the Polygastria are thus resolvable into very natural families, he proceeds to classify them in the following manner: — 1| Family 1. — Monadinid^ ( Monadida ). Polygastric animals, without intestinal canal, without external shell, body uniform, dividing by simple spontaneous fissure into two, but by cross divisions into four or several individuals. Monas. Uvella, (1,/^. 1.) Polytoma, (2, 1 •) Microglena, {3, fig. 1.) Phacelomonas. Glenomorum. Doxococcus. Chilomonas. Bodo, (4, Jig. 1.) Family 2. — Cryptomoxadinid^. Poly- gastric animals, presenting all the characters of the Monadinidae, or at least deprived of the characteristic features of other families, and individually enveloped in a soft or slightly indurated shell. Cryptomonas. Ophidomonas. Porocentrum. Lagenella, {5, fig. 1.) Cryptoglena. Ti-achelomonas. Family 3. — Volvocinid^e. Polygastric ani- mals, without intestinal canal, without external • EVTEpov, intestine ; JnXoc, manifest. t kvkXo;, a circle ; xoTXof, large intestine. i ofBi:;, straight ; koiXo;, intestine. § KafxirvXot;, crooked ; xoTxo?, intestine. II In the following list it will be perceived we have omitted altogether the numerous families of Baccillaria; and kindred forms, being by no means satisfied as to their claims to rank as members of the animal creation. They stand, indeed, very dubiously between the domains of zoology and botany. 4 POLYGASTRIA. appendages, and with the body uniform, similar to the monads, but provided with an external en- velope or shell, and dividing by complete spon- taneous fissure beneath the common envelope into a number of animals which take the form of a polypary. At length the envelope beconies ruptured, and gives passage to the divided animals, which in their turn renew the same process of developement. Gyges. Pandorina. Gonium, (7, 8, fig. 1.) Syncrypta. Synura. Uroglena. Eudorina, (9, 10, fg. 1.) Chlamidomoiias. Sphserosira. Volvox, (fig. 3.) Familt/ 4. — V'^ibrionid^. Animals either distinctly or most probably polygastric ; fili- form ; without alimentary canal ; witliout shell or external appendages ; with the uniform body of Monads; associated in filiform chains in consequence of imperfect spontaneous {tra)is- verse ) division. Bacterium. Vibrio, (1, 2, 3, 4, 5,/-. 5.) S pi roc h seta. Spirillum. Spirodiscus. Family 5. — Clostehinid^. Animals dis- tinctly or most probably polygastric, without alimentary canal, and without external appen- dages; body uniform, resembling the Crypto- monadinidag in their envelope or shell, and dividing, together with their envelope, by spon- taneous, transverse fissure, into a bacilliform or fusiform polypary ; provided with moveable papillae situated in the aperture of the shell. Closteiium, (6, 7, fig. 5 ) Familj/ 6. — Astasiead>e. Animals evi- dently or apparently polygastric, without ali- mentary canal, without external appendages or shell ; changing their form to caudate or ecau- date at pleasure ; body with a single aperture. Astasia, {I, fig. 6.) Amblyophisj (2, fig. 6.) Euglena, (3, /-." 6.) Chlorogonium, {"i, fig- Q.) Colacium, (5, fig. 6.) Distigma. Family 7. — Dinobryina. Animals dis- tinctly or apparently polygastric ; without in- testinal canal ; body with a single aperture ; without external appendages; changing their form at will, and invested with a shell. Epipyxis. Family 8. — Amoebaead^ (Proteiform Animalcules ). Polygastric animalcules with- out alimentary canal; body with a single opening, furnished with variable processes, the shape of which changes at will; without a shell. Amoeba, (7, 8, 9, 10, 11, 12, 13, fig. 6.) Family 9. — Arcellinid*. ( Capsule Ani- jnalcules). Animal polygastric, anenterous, loricated ; body multiform, furnished with changeable foot-like appendages, covered with a univalve urceolate or scutellate shell, with a single aperture. = Amoeba enclosed in an urceolate or scutellate shell. Difflugia, (l,^g. 7.) Arcella, (2, fig. 7.) Cyphidium, (3, fig. 7.) Family 11. — Cyclidinid^ (Disk Ani- malcules). Animals polygastric, anenterous, provided with appendages in the form of cilia or setae ; destitute of shell. Cyclidium. Pantotrichura. Chaetomonas. Family 12. — Peridinaead.?: (Wreath Animalcules). Animals visibly or probably polygastric, anenterous, loricated, vibrating ; having setae and cilia dispersed over the body or shell often in the form of a zone or crown ; shell with a single opening. Chaetotyphla. Chaetoglena. Peridinium. Glenodinium. Family 13. — Vorticellinid.?: (Bell Animalcule ). Animals polygastric, having a distmct intestinal tube, with two openings, the oral and anal apertures being distinct, but situated in a depression common to both ; without shell; either solitary and free, or fixed and frequently associated, developing them- selves by imperfect spontaneous division, and frequently assuming the form of beautiful little bunches. Stentor, (fig. 8.) Trichodina. Urocentrum. Vorticella, (fig. 9.) Carchesium. Epistylis. Opercularia. Zoothamnium. Family 14. — Ophrydinid.i (Loricated Bell Animalcules ). Polygastric animalcules, having a distinct intestinal tube, the apertures of the mouth and anus being distinct, although situated in the same fossa ; loricated; solitary or aggregated. ( = VurticelUna loricatu.) Ophrydium, (fig. 10.) Tintinnus. Vaginicola, {9, fig. 11.) Cothurnia. Family 15. — Ekcheliad^; (Rolling Animalcules). Animals polygastric ; having a distinct intestinal canal, the apertures of the mouth and anus being situated at the opposite extremities of the longitudinal axis of the body; without a shell, Enchelis, (1,2, 3,4,5,.^^'. 11.) Disoma, (6, 7, fig. 11.) Actinophrys. Trichodiscus. Podophiya. Trichoda. Lachrymaria, (8, fig. 11.) Leucophrys, {I, fig. 12.) Holophrya. Prorodon {2, fig. 12.) Family 16. — Coi.EPiNio.t (Box Ani- malcules). Polygastric animalcules, having a distinct intestinal canal, the mouth and anus POLYGASTRIA. 5 being situated at the opposite extremities of the body; loricated. = Kncheliadse furnished with a shell. Coleps, (l,2,/g.l3.) Family 17. — Trachelinidje (Neck Animalcules), Animals polygastric, furnished with a distinct intestinal canal, having an oral and an anal opening, but of these the anal opening only is terminal ; without shell. Trachelius, (3, 4y5,f g. 13.) Loxodes. Bursaria. Spirostoma. Phial ina. Glaucoma. Chilodon. Nassula, (1, fig. 16.) Family 18. — Ophryocercinid-e ( Swan Animalcules ). Animals polygastric ; having a distinct intestinal tube, furnished with two openings, that of the mouth only being termi- nal ; without a shell. Trachelocerca, (3, 4, 16.) Family 19. — Aspidiscinid^ (Shield Animalcules). Polygastric, loricated, animal- cules ; having an intestinal canal furnished with two orifices, of which one only, viz. the anus, is terminal. Aspidisca. Family 20. — Colpodead^e ( Breast Ani- malcules). Animals polygastric ; without a shell ; intestinal canal distinct, with two open- ings, neither of which is terminal. Colpoda, (2, 3,fg. 18.) Paramecium, (1, 4, /g. 18.) Amphileptus, (2, Jig. 16.) Uroleptus. Ophryoglena. Family 21. — OxYXRiCHiNiDiE (Hackle Animalcules. ) Animals polygastric ; without shell ; having an intestinal canal with two dis- tinct orifices, neither of which is terminal; pro- vided with vibrating cilia, and also with styles or uncini, which are not vibratile. Oxytricha. Ceratidium. Kerona. Urostyla. Stylonychia. Family 22. — Euplotid^. (Boat Ani- malcules.) Animals polygastric, loricated; with a distinct alimentary canal having two orifices, neither being terminal. = Aspidisca with neither orifice terminal, or Oxytricha pro- vided with a shell. Discocephalus. Chlamidodon. Himantophorus. Euplotes, (Jig. 19.) All the above families are grouped by Ehren- berg under the following orders and sections, which, as it will facilitate the observations of the microscopist, as well as be a convenient guide to us in studying the economy of these little beings, we will subjoin in a tabular form, premising that the illustrious naturalist of Berlin found it advisable to separate the Poly- gastria into two parallel series, one comprising all such as were destitute of a shell (Nuda), the other embracing those which are furnished with such a covering (Loricata). ANENTERA. This includes all animalcules which possess neither an internal nutritive tube nor an anal orifice, the mouth being in communication with several nutritive vesicles. These may be divided into the following sections : — l.s^ Section. Gymnica. Animalcules whose body has no external cilia nor pseudopediform prolongations. Nuda. Loricata. Monadina. Cryptomonadina. Vibrio. Closterina. 2d Section. Epitricha. Exterior of the body ciliated or furnished with setae and without pseudopediform prolon- gations. Nuda. Cyclidina. 3d Section. Loricata. Peridinaea. PSEUDOPODIA. Body provided with variable pseudopediform prolongations. Nuda. I Loricata. Amoeba. | Bacillana. Second Division.— ENTERODELA. This division includes all animalcules having an internal digestive canal provided with a mouth and anal opening. 4th Section. Anopisthia. Mouth and anus contiguous. Nuda. I Loricata. Vorticellina. I Ophridina. 5tk Section. ENANTroTREXA. Mouth and anus terminal and opposite ; re- production by transverse division. Nuda. I Loricata. Enchelia. | Colepina. 6th Section. Allotreta. Mouth and anus terminal and opposite, as in the last section ; reproduction by longitudi- nal and transverse division. Loricata. Aspidiscina. Katotreta. reproduction Nuda. Trachelina. 7th Section. Mouth and anus not terminal : as in last section. Nuda. Loricata. Kolpodea. Euplota. Oxytrichina. Taking the above classification for our gui- dance, we must now proceed to investigate more minutely the organization of the strange animals included in this extensive series. Locomotion. — Although no special locomo- tive apparatus has as yet been discovered in the family of Monads, this perhaps depends rather upon our deficient means of investigation than upon their absence. Attentive observation shews that every true Monad is furnished with a minute filiform proboscis, (1, 2, 3, Jig. 1,) which, as it constantly exhibits an un- dulatory or vibratory motion, has been mis- taken by some observers for a ciliary apparatus. Sometimes two of these organs are present, but this cannot be regarded as an essential charac- teristic feature, seeing that during the process of spontaneous fissure an animalcule which previously had only one proboscis, becomes G POLYGASTRIA. furnished with two preparatory to its separation into two individuals. In some species, how- ever, two are constantly present. These pro- boscides may possibly discharge a double func- tion, and perform the duty both of locomotive and of prehensile organs with which to collect nourishment. In the Cryptomonadinidae likewise one or two filiform proboscides, similar to the above, seem to be the locomotive organs ; and the vibratile apparatus that serves for the move- ments of the Volvoces is entirely composed of similar structures belonging to the individual animalcules that constitute the compound bo- dies of these wonderful beings. Amongst the Vibrionidae the locomotion is of a very different character. In the true Vibrios it is performed by a kind of meandering or undulating movement, the fibre-like com- pound body of the animal bending and straight- ening itself alternately, the cause of which seems to depend upon a stronger binding together and subsequent relaxation of the individual animalcules, so that these seem to displace one another. In Bacterium the contraction is weaker, so that no undulating movement is produced, although the creature swims straight forward. In the family Closterina (6, 7, Jig. 5) the lo- comotive organs consist of numerous short, soft, conical papillae, situated near the openings of the shell at the two opposite extremities of the animal ; they are placed upon the inner side, and can be protruded but a very little way from the shell. In the family Amoeba no special locomo- tive organs are met with. The round, gelati- nous, and highly contractile bodies of these creatures have the capability of thrusting out at will foot-like processes from any part of their body, by the assistance of which they manage to move about. A similar mode of progression is met with in the Ai'cellinidae. In all the higher forms of Polygastric Infusoria locomo- tion is effected by means of cilia variously distributed over different parts of the body, but their position in different genera will be described when speaking of the external forms of the different families. These cilia are described by Ehrenberg to be minute hairs arising from a thick bulbous basis, upon which they execute a rotatory mo- tion, some of them being continuous with their basis, while others are only articulated there- unto ; of these the former kind exists in Sti/lo- nychia mytilus^ and the latter in Paramecium aurelia. In addition to the cilia some forms of ani- malcules (Oxy trichina) possess seta^ which are likewise stiff moveable hairs, but which are without any power of vibration ; these organs are used m standing and climbing. Sometimes they are without any thickened basis, as in Actinophrya ; generally they are pointed, but occasionally have a knob at the end. A fourth set of locomotive organs are the atyli. These are thick straight setze, which in some forms of animalcules are attached like the tail fea- thers of a bird to the hmder part of the body ot the animalcule : such styli do not vibrate Kke cilia, neither are they implanted in a bulb-like basis, nor bend like hooks, but serve merely as instruments of support, or are useful in climbing the stems of aquatic plants. Lastly, many races are furnished with uncini or booklets ; these are merely bent, hook-like seta, which, being thick and strong, and situ- ated upon the venti-al surface of the animal- cule, seem to take the place of feet : they do not vibrate, but are implanted into a bulb-like root, which permits them to be moved in all directions ; and although they are not articu- lated, they resemble very much the limbs of articulated animals. So various, however, are the forms of the different families of Polygastric animalcules, that the above general view of their locomotive organs gives but a very imperfect idea of this part of their economy; and it will, therefore, be ne- cessary, before we proceed further, to describe more at length some of the most interesting ge- nera belonging to the class, for so strange and re- markable is the organisation of some of them that no generalisation would answer our present purpose. Some are single and isolated indivi- duals, moving freely wherever they list ; others are strangely compounded of aggregations of numerous animalcules associated into one com- mon body, all of which must cooperate in rowing about the microcosm which they col- lectively form ; some are affixed to highly irri- table stems, whereby they are attached to various foreign bodies; some are naked, others covered with shells: in short, nothing but a rapid glance at the whole group will enable us satis- factorily to discuss the many curious circum- stances discovered in connection with their history. The family Monadinid^ embraces nume- rous animalcules, which, however different in external appearance, are evidently related to each other in all essential parts of their struc- ture. The Monads, properly so called, are so small that the utmost penetration of the miscroscope is insufficient to display their outward form with any degree of distinctness, much less to reveal their internal structure, some of them being not larger than from the 1,000th to the 3,000th of a line, or the 36,000th part of an inch in diameter. Under the highest powers of the microscope they have the appearance of almost invisible globular active specks, swim- ming about with the greatest facility, and never impinging against each other during the rapid dance that they continually execute. Their numbers are absolutely beyond human appre- ciation, as may be readily understood from the following computation of the multitudes some- times met with. The Manas crepiiscuhim, found in infusions of putrid flesh, crowds the drop of water in which it is found to such an extent that there seems to be no interspace whatever between the individual animalcules. Supposing these animalcules to be, as is generally the case, ^'j^gth of a line in diameter, their number will then amount, in a drop of water of the size of POLYGASTRIA. 7 a single cubic line, to eight thousand millions, and a cubic inch of such water containing 1728 cubic lines, will be peopled with thirteen billions eight hundred and twenty-four millions of these living and active beings ! ! I It has been possible to detect, even in these smallest of nature's works, an apparatus that seems to perform the functions of an instrument of progression. This consists in one or some- times two filaments of extreme tenuity, which resemble somewhat the tail of a tadpole ; here, however, the organ performs the functions of a proboscis, being appended to that part of the body which advances first in swimming. The shape of the Monads is not always globose, but sometimes egg-shaped, pear-shaped, elon- gated, or fusiform. In Monas tingens we have Fig. 1. 1. Uvella glaiccoma. 2. Polytoma uvella, 3. Afi- crofjlena monadina. 4. Bodo socialis. 5. Lagenella euchlora. 6. The same crushed, showing its shell. 7. Gonium pectorale. 8. Gonium pectorale, hrediYing up into its component animalcules. 9. Eudorina. 10. One of the animalcules comprising Eudoritui detached. 11, 12, 13. Developement of Volvox. an example of the last form, and also of the manner in which they are sometimes found associated by their tails into beautiful groups, their double proboscides being all protruded externally. This faculty of clustering together is still better exemplified in the genus Uvella, (1, Jig. 1^) which somewhat resembles a trans- parent mulberry rolling itself about at will, whence the name grape monad," which these animalcules bear. In Polytoma (2, fig. 1) this clustered appearance is due to the fact that the original animalcule is continually dividing into a greater and still greater number, which, at last breaking loose from each other, become solitary and independent. Some animalcules of this family, as Chilo- monas destruens, live in the interior of dead Rotifers and other minute beings, in which locality they seem to revel luxuriously ; whilst others, as Bodo, (4, fg. 1,) are met with in the intestinal canal of many living animals,* from the fly and the earth-worm up to fishes and even men. One species (B. ranarum) seems particularly partial to the intestmes of Frogs, in the contents of which it is usually found. Many species of this genus are fur- nished with long tails, by the aid of which * Ehrenberg, Infiisionsthierchen. they are bound together in bunches of very beautiful appearance, as represented in the figure. In the Cryptomonads, (5, fig. 1,) which seem to be merely Monads invested with a shell, the proboscis is of a similar character; but these animalcules are never found asso- ciated in bunches. Perhaps few more beautiful objects exist in nature than the next group of animalcules belonging to the Monadine type. These are the Volvocinidae, embracing several genera composed of numerous Monads, associated together and connected by a common envelope, which constitutes a kind of compound poly- pary or monadary, as it has been recently called, through which the proboscides of tlie com.ponent Monads are exserted. In Gonium, (7, 8, Jig. 1,) one of the simplest forms belonging to this family, the common body resembles a minute square- shaped flattened tablet, so transparent as to be detected with great difficulty, in which the green Monads are set like the gems in the breastplate of the Jewish high-priest, from which circumstance one species, G. pectorale, has been named. The organisation of Gonium pectorale, as far as it has been made out, seems to be as follows ; — The mantle or proper covering of each individual animalcule, wliich can only be properly examined after the division of the little tablet, is neither four-cornered nor table- like, but pretty nearly round, and in the form of a lacerna, which the animalcules can quit and renew again at intervals. The table-like investment of the compound body is produced by regularly repeated spontaneous fissure in the longitudinal, but not in the transverse di- rection, which is in fact only an imperfect division into single tablets. In a little tablet of this kind all the animalcules of which it is composed appear to be connected to each other by riband-like prolongations. It is only in Gonium pectorale that locomo- tive organs have been satisfactorily detected, presenting themselves under the usual form of two thread-like proboscides, appended to the mouth of each individual Monad entering into its composition. These are seen to be in con- stant motion, so as to have the appearance of cilia. Each individual animalcule inclosed in the common envelope of the compound being a}> pears, moreover, to possess a distinct nutritive apparatus, consisting of transparent vesicles visible among the green matter that fills its interior ; but these have not yet been observed to fill themselves with colouring matter. Eh- renberg likewise supposes that each of the component animalcules of the Gonium contains the essential parts of a double sexual system, regarding the green-coloured particles in the body as eggs, and an opaque spot and con- tractile bladder, which is occasionally discern- ible, as the male apparatus; but these parts will be more particularly described hereafter. The most beautiful animalcules belonging to the Volvocinidee are the Volvocts, from which POLYGASTRIA. tlie family derives its name. These, which may readily be procured in summer time, are sufficiently large to be visible to the naked eye, and when examined with a microscope, even of very humble power, present a spectacle of indescribable beauty ; turning continually upon their axes, and revolving majestically through the drop of water that forms their space, they have the appearance of so many microscopic worlds (fs- 2)- The parietes of these elegant spheres are thin and pellucent as the walls of an air- bubble; and in their interior, which is obviously fluid, may at times be seen rotating on their axes a second generation moving freely in the interior of their parent, and only awaiting the Fig. 2. Volvox Globator^ much magnified. destruction of the original Volvox to escape from their imprisonment. It was Ehrenberg* who first made the dis- covery that these beautiful living globes were not, as had until then been universally believed, single animalcules producing geramules in the interior of their transparent bodies, which on arriving at maturity by their escape through the lacerated integument of the parent termi- nated its existence, but that they formed in reality the residences of numerous individuals living together in a wonderful community. This great observer had long remarked that the Volvoces appeared to take no food, neither were any of those vesicles discernible in their interior which in all other races of Infusoria he regards as the organs of nutrition — a circum- stance which, considering their very great size when compared with other races, was well calculated to arrest attention ; and he soon found that the structure of their nutritive appa- tus lies much deeper and is of a far more delicate character than any one could have previously anticipated. On attentively examining with glasses of high power (1000 diameters) the minute green specks which stud the transparent covering of the Volvox, and which he had previously re- garded as the bulbous roots of locomotive cilia, he perceived in each corpuscle a bright red point, and moreover discerned that instead of its being a cilium which was appended thereto, it was a whip-like moveable proboscis exactly similar to that of the Monads described above ; and further observation convinced him that every green point was in reality a distinctly organised Monad, possessing mouth, eye, sto- machs, generative apparatus, and, in fact, all the viscera attributed by Ehrenberg to the free Monadinidae, and that the A^olvox was entirely made up of an association of similar individuals (h- 3). Fig. 3. A portion of Volvox Globator still further magnified. He further observed that in young specimens the component animalcules were perpetually undergoing spontaneous fissure, the result of which was the regular production of two, four, eight, sixteen, thirty-two, &c. distinct animal- cules from one individual, until the resulting globe, i. e. the Volvox, was completely arrived at its natural dimensions. The Volvox Globator may therefore be re- garded as a hollow tegumentary vesicle, the origin of which is due to the incomplete spon- taneous fissure of innumerable Monads, each of which is not more than 1 .500"^ in diameter, but all completely organised. FiiT. 4. * Abhandlungen der Konigiichen Academie-^r An individual nwnadine. of Volvox Globator magnifed VVissensthaften zu Berlin, Jahr 1833, p. 328, 1000 diameters. POLYGASTRIA. 9 Oti closer inspection it is seen that all the jVlonads, which are placed at regular distances, communicate with each other by delicate threads, which form a kind of reticulation in the com- mon gelatinous skin-like integument of the compound body, or polypary, as it might be aptly called, out of which the contained ani- malcules only protrude their proboscides either in search of food or to row the general mass along. It is easy to prove by flattening the Volvox between two plates of glass that its interior is only filled with water, in which sometimes there may be observed smaller volvoces swim- ming about, the products of the propagation of some of the constituent animalcules. These are not solitary young ones, but may already be seen to be composed of numerous individuals, formed by the continual division of the original from which they sprang. Another mode of reproduction is by the laceration or division of the globe itself. When this takes place, either for the escape of the included Volvoces generated within, or from any other cause, the component Monads im- mediately prepare to leave their domiciles, and tlie individual animalcules become separated by the dissolution of the inter-communicating threads ; they then, by little and little, extri- cate themselves from the common gelatinous envelope, and creep out to commence an inde- pendent existence. The gelatinous polypary of the original Volvox in consequence speedily loses all its green spots ; and as every little point is active, moving its proboscis freely when it leaves the common globe, it may fairly be concluded that they have a power of indepen- dent existence, and that each is able to begin the construction of another compound Volvox as wonderful as that we have been considering. The developement of the embryo of the Volvox is represented in 11, 12, 13, Jig. 1. In ll,j^^. 1, is represented the simplest con- dition of a granular mass containing a clear central spot, which in the course of a lew hours assumes the condition represented in 12, Jig. 1, by undergoing an imperfect spontaneous division. By a continued repetition of this division it becomes at last broken up, until it has the appearance shewn in 13, Jig. 1. The component vesicles still go on subdividing, until it assumes the appearance of a single perfect Monadine possessed of two proboscides, eye-spots, &c. By a further developement it constructs for itself an external envelope, which has the appearance of a white ring surrounding the central nucleus. Wonderful as is the organisation of the last family, it would probably not be more so than that of the Vibrionidae, was it in our power to display their internal economy in an equally satisfactory manner ; but such is the extreme minuteness of all the members of the family, that even to Ehrenberg this seemed a hopeless wish. The Vibrionidae present themselves under the microscope as thread-like bodies of in- describable tenuity, worming their way in countless thousands through the drop of water in which they live, and presenting themselves in different shapes, which have been classified as belonging to five distinct genera, named as follows: — The first, Bacterium, contains those forms which exhibit the appearance of stiff- jointed filaments. In the second, Vibrioy the Fig. 5. 1, 2, 3. Vibrio subtilis. 4. Vibrio riigula. 5. Vibrio rugula more highly magnijied. 6. Closterium monili' ferum. 7. Closterium turgidum. a, a, a, three large aggregations of living cor- puscles ; X, X, the locomotive papillae ; o, o, open- ings in the shell. creatures resemble minute chains, which seem to be as soft and flexible as the body of a serpent, although so exceedingly minute that some species have been calculated to be not more than the 300th of a line long, and the 3000th of a line in thickness. The animalcules in some genera assume the appearance of tortuous chains or flexible spiral threads. In Spirillum the body seems rolled into a stiff spiral cylinder, and in Spirodiscus it is arranged in a kind of disc. On examining these little beings while alive, little doubt can be entertained that they belong to the animal series of creation : the manner in which they obviously direct their course at will, and the facility with which all their movements are performed, have caused them to be recog- nised as animals by all observers. It is, how- ever, to Ehrenberg that we are indebted for the discovery of their real nature. From his ob- servations we learn that these living filaments, minute as they are, are not single animals, but chains composed of numerous associated individuals produced from each other by spon- taneous fissure. There even seems to be reason to suspect that their internal structure is in some degree allied to that of the Monadines ; at least in one species. Bacterium triloculare, Ehrenberg perceived a proboscidiform mouth similar to that possessed by the Monadines of Volvox. The peculiar forms assumed by the different genera of Vibrionidae seem to depend upon the character of the fissiparous division by which the whole chain is produced, the compound body remaining straight or becoming thrown into spiral folds as the division is equably or unequably carried on. The snake-like movements of the true Vibrios during their progress in the water, Ehrenberg conceived to be produced by a power of con- tracting forcibly, that resides in the individual 10 POLYGASTRIA. segments of the compound body, which enables them to change their situation relative to each other. In the next family, Closterium, (6, 7, Jig. 5,) the locomotive organs present themselves under a very different aspect, as, indeed, do the animalcules themselves. The animalcules are incased in a thin, transparent, shuttle-shaped shell, or mantle, (urceolus,) which is in many species evidently open at both ends. Enclosed in this shell is the exceedingly soft and trans- parent mucus-like body of the animal, which is frequently entirely full of green-coloured granules and little vesicles. The shell or mantle, when exposed to heat, is reduced to ashes and entirely volatilized, crisping up during the process like horn. The locomotive apparatus is exceedingly sin- gular in its conformation ; it consists of nu- merous very short, delicate, transparent organs, having the form of conical papillae : these are situated in the neighbourhood of the two open- ings in the mantle, lying in the inner space, and can be protruded externally to a short distance. It becomes evident, on mixing a few coloured particles with the fluid in which the animal is contained, that these are instruments of loco- motion. The family Astasia {\, fig. 6) contains nu- merous genera remarkable for the contractile power of their bodies, which causes them con- tinually to change their shape, and consequently they become very puzzling objects to the inexpe- rienced microscopist. Many of them are exceed- ingly beautiful on account of their rich colours ; and so enormously do they abound under certain circumstances, that the water in which they are found is changed to red, green, or yellow, in accordance with the tint of the species which multiplies therein. In many species of this family, contractile proboscides have been found to exist, which most probably form the loco- motive apparatus common to the group. Ani- mals very similar to the Astasians, but lori- cated, constitute the family Dinobryina^ (6, fig. 6,) the envelope forming an urceolus, in which the highly contractile body of the ani- malcule is lodged, having much the appearance of a microscopic Sertiduria. In the next family, Aifioeba, locomotion is accomplished in a most extraordinary manner, these animals apparently possessing the power of making foot-like processes for themselves, or dispensing with them altogether, just as cir- cumstances render it convenient. The Amoeba, or Proteus, as it was formerly named on ac- count of the facility with which it changes its form, seems to have its body composed of a greyish mucus-like jelly, the shape of which is perpetually changing, sometimes shrinking into a rounded mass, then extending itself in all directions as though it was entirely fluid, or sliooting out processes of different kinds from any part of the periphery of its body : its movements indeed seem to be rather fluent than progressive, so easily dees it mould itself to any required form. It is, nevertheless, very voracious, and its shape is frequently found to be modified by the contour and dimensions of other animalcules which it may have swal- lowed. ( 7, 8, 9, 10, 11, 12, 13,/^. 6.) Fig. 6. 1. Astasia Jiavicans. 2. Amblyophys viridis. 3. Euglena aais. 4. Chlorogonium euchlorum, 5. Co- lacium stentorum on a portion of the leg of a monoculus. 6. Dinobryon sertularia. 7, 8, 9, 10, 11, 12, 13. Amoeba diffluens, exhibiting a few of its changes of form. The genera Difflugia, Arcella, and Cyphidium (1,2, 3, fig. 7) seem to be merely Amoebae endowed with a power of constructing for them- selves a carapax or shelly covering of various forms, from the orifices of which the fluent body of the animalcules can be made to protrude, and thus become convertible into instruments of locomotion. In Cyclidium, Pantotrichujn, and Chato- monas, and their loricated representatives, Chie- toti/pla, Cficetoglena, Feridiiiium, and Glemu dinium, forming the families Cyclididae and Peridinaeadae, we first find a new system of locomotive organs making their appearance in the shape of vibratile cilia. The locomotive cilia are variously disposed in different genera ; sometimes they are disse- minated over the entire surface of the animal, either irregularly or arranged in regular rows ; sometimes they are only partially distributed or are confined to the region of the mouth and anterior part of the body ; but, whatever their situation, their action is similar; they are inces- santly in a state of active motion, either pro- pelling the anmialcule through the water, or causing currents to flow in definite directions, by the agency of which food is brought to the oral opening. Fig. 7. 1. Diffltigia ohlonga. 2. Arcella dentata. 3. Cy- phidium uureolum. POLYGASTRIA. The genus Stentor (fig. 8) contains some of the largest and most active animalcules be- longing to the class, and, as might be expected, these are amongst the most conspicuous for the perfection of their locomotive organs. These beautiful creatures resemble gelatinous trum- pets, the bodies of which are flexible and con- tractile in all directions, either while swimming about freely in the water, or while attached, as they frequently are, to some foreign body by means of a little sucking disc which terminates the pointed extremity of the tail. The whole of the trumpet-shaped body of Stentor is covered over with innumerable cilia, disposed in regular rows, and of sufficient size to be easily distinguishable by the microscope. Its broad end is terminated by a circular disc, the diameter of which is considerably larger than the widest part of the body. The entire surface of this disc is likewise covered with multitudes of cilia, arranged in regular con- centric circles; and, moreover, its margin is fringed all around with a single row of cilia of larger dimensions, which by the rapid succes- sion of their movements give the appearance of a wheel spinning rapidly round, and by its revolution causing powerful currents in the sur- rounding water. At the lower part of the margin of the ciliated disc the ciliary zone ^ig- 8. turns inwards, forming a spiral fold around a funnel-like aperture (jig. 8) which leads to the mouth, and likewise lodges the orifice through which digested materials are cast out. The currents caused by the marginal fringe around the disc are all directed towards the oral aperture, and consequently, by bringing nutritive particles to the mouth, this part of the apparatus becomes eminently subservient to nutrition. In several species of Stentor, in addition to the apparatus of cilia described above, there is an additional riband-shaped band of these vibratile organs extending from near the mouth to a considerable distance towards the hinder part of the body, the outline of which has an undulated appearance. The Trichodinae, or Urn animalcules, have no pedicle or elongated tail, but are provided with a fasciculus or circlet of cilia situated in front of their bodies, which are disc- shaped, bowl-shaped, or conical, the mouth being ap- parently a single orifice situated in the ciliary circlet. One species of this group, T. pedicu- lus, seems to be parasitically attached to the Hydra viridis, and allied forms have been met with in the respiratory laminae of several bi- valve shell-fish, ( Anodonta, Unio^ &lc.,) and also in Gyrodactylus coronatus, itself a parasite inhabiting the gills of the Crucian Carp /^Cy- prinus Carassius ). That these animalcules are really Polygastrica, and not sterelminthous en- tozoa, Ehrenberg satisfied himself by feeding them with indigo. Urocentrum seems to be similarly organized, only it is furnished pos- teriorly with a sharp style-like process. But perhaps the most remarkable as well as most elegant of all the forms of animalcules belonging to this group are the VorticellcBy (fig. 9,) the sight of which cannot fail to exact the untiring admiration of the microscopical Fiif, 9. Stentor Roeselii, highly magnified, t, viscus supposed by Elirenberg to be the testis. Vorticella cyathina. h, c, d, e,f, exhibit the various steps of fissiparous reproduction in this animalcule. 12 POLYGASTRIA. observer. These beautiful little creatures might be compared to wine-glasses of microscopic dimension, the bells of which are fixed to liighly irritable stems, that are attached by their opposite extremity to some foreign body. These stems are endowed with the capability of extending themselves in the shape of straight filaments of exquisite tenuity, and on the shghtest alarm or irritation, of shrinking into close spiral folds, so as to draw the little bell as far as possible from danger. The mouth of tiie bell is fringed with a circlet of cilia, which vibrate rapidly at the pleasure of the animal, causing a magnificent whirlpool in the sur- rounding water, which brings nutritious sub- stances that may be in the neighbourhood towards the oral oiifice, the situation of which is nearly the same as in Stentor, above described, and thus the little being is abun- dantly supplied with food. Tlie true Vorti- cellae, although generally found grouped toge- ther in elegant bunches, always have single undivided stems; but in the genus CaT'chesimn, the animals of which are similarly organised, the pedicles sprout from one another so as to have a branched or ramose appearance, while in the genus Epistj/lis, animals similar to Vor- ticella and Carchesium are met with, the stems of which are quite stiff and inflexible, so much so indeed that the animalcules belonging to this group have obtained the name of " pil- lar bells " ( San len glue Pic hen). The family Op/uydinida presents us again with very remarkable forms of Polygastric ani- malcules, allied in structure to the Vorticella, but having their bodies inclosed in cases of different kinds, of which it will be necessary to give one or two examples. The genus Ophrt/dium, (jelly-bell-animal- cules,) of which the Ophrydium versatile Q/ig. 10) is an example, was regarded by the older Fig. 10. Section of a portion of the periphery of Ophrydium versatile, showing the manner in which the individual animalcules are implanted in the mass. naturalists as being a mass of vegetable matter, and had the names of ulva, fucus, conferva, &c. conferred upon it by different authors, until MUller, in 1786, first announced its real nature and relationship to the vorticelline animalcules. It is found under the shape of a gelatinous mass of a lively or dull green colour, which in consistence may be compared to frog's spawn, some specimens attaining the size of four or five inches in diameter; the whole forming an irregularly shaped but smooth mass, which is composed of many millions of distinct animal- cules, each about j'gth of a line in thickness, and about the Vot^ of a line in length. The space of a square line would therefore contain 9216 of these diminutive beings; a cubic line six times as many, or 55,296 ; and a cubic inch nearly eight millions, namely, 7,962,624. In the water all these congregated animalcules are disposed in close rows, something in the same manner as in Volvox. On shaking the mass many others show themselves within be- tween the former, so as to form from three to five different ranks. At first all the gelatinous cells appear to be connected with the centre of the mass by filamentary prolongations, but these disappear as they proceed internally, so that the middle seems to be hollow and full of water ; the whole, indeed, might be compared to the gelatinous polyp masses ( Alci/onida ) found upon the sea-shore, only the structure of the animalcules is polygastric and not that of polyps. In the other genera belonging to the family Ophrydinidae, namely, Tintinnus, Vaginicola (9, Jig. 11,) and Cothurniu, although living in gelatinous transparent sheaths, and resembling Vorticellai in their structure, are not associated in masses, but remain permanently detached and solitary. The family Encheliadae contains various forms of animalcules, having the oral and anal orifices distinct and situated at the opposite extremities of the body. The different genera of which it is composed may be distinguished as follows : — Enc/telis, (revolving animalcule,) has its body flask-shaped, {'iyjig- 11,) without any cilia externally, but witli a circlet around the mouth, which is suddenly truncated and desti- tute of any dental armature. Disonia, ( double-bodied aniin(dculcy) crea- tures nearly resembling Enchelis in form and structure, but with a double body {6,7, Jig. 11). Actinophrj/a, (sun aniwalcule,) having the exterior of the body unprovided with loco- motive cilia, but stuck over with setaceous ten- tacula which radiate in all directions. Triclwdiacua, (radiated disc animalcule,) re- sembling Actinophrys, only the body is here Fig. 11. 1, 2, 3, 4, 5. Enchelis farcimen, swallowing food. 6,7. Disown vacillans. 8. Lachrymaria proteus, 9. Vaginicola decumbens. POLYGASTRIA. 13 compressed, and only furnished with a single row of setaceous teutacula, situated around its margin. Fodophi/ra, ( radiated foot animalcule^) is an Actinophrj'S with a spherical body, from which projects a long straight pedicle, which, however, is not attached to any foreign body. Trichoda, (hair animalcule,) an Enchelis having its mouth obliquely truncated and fur- nished with a lip; its body is unprovided with a neck-like prolongation. Lacluymaria, (lachrymatory animalcule,) (8, fig. 11,) an Enchelis having its body destitute of cilia externally, but terminated by a long thin neck, which is clavate at the extre- mity, and ends with a mouth provided with a lip and ciliated margin. Leucophrys, (ciliated animalcule,) an En- chelis, with its body entirely covered with vibratile cilia — its mouth is obliquely terminal ai)d provided with a kind of lip, but without dental organs. (1, fig. 12.) Holophrya, (woolly animalcule,) an En- chelis having the exterior of its body entirely ciliated. Prorodon (toothed rolling animalcule). In this genus, like the last, the body is covered all over with vibratile cilia, and the mouth Fig. 12. 1. Leucophrys pattela. 2. Prorodon terei. 6, mouth ; c, outlet of alimentary tube. truncated, but the latter is remarkable for being armed with a circlet of teeth of a very peculiar structure situated within its margin. (2,/g. 12.) Ihe family Colepinidae consists of but one genus, Co/eps (1, 2, fg. 13), the animalcules belonging to which have all the characters of Enchelis, except that they are loricated. These animalcules are found among confervse, more especially in summer time. As lone as they are swimming it is difficult to perceive the transparent case in which they are enclosed ; but if tliey are allowed to get dry or are crushed between two plates of glass, its presence be- comes manifest as well as its brittleness. In shape this external covering resembles a little barrel made up of rows of plates or rin^s, be- tween which the cilia seem to be exserted (teatula multipartita ). Anteriorly it is trun- cated, its margin being either smooth or toothed, and posteriorly terminates in three or five little sharp points. The next family, Trachelinida, contains all those non-loricated animalcules whose alimen- tary canal has two distinct orifices, but of which one only, the anal, is terminal. The genera that belong to it are very interesting objects, and many of them of great beauty. The reader Tier. 13. 1, 2, Coleps hirUis. 3, 4, Trachelitis anas. 5. Tra- chelitis ovum. Oy mouth; o, outlet of alimentary canal. will be able readily to recognise them by the following characters : — Trachelitis ( neck animalcules, 5, Jig. 13). These may be readily knowTi by their exces- sively elongated upper lip, which has the appearance of a long proboscis, or rather, per- haps, resembles the neck of a goose or swan, from which circumstance some species ( Tra- chelius anas) have received their best knovvn appellations. Attentive examination, however, shews that the mouth is situated at the bottom of this neck-like prolongation (3, ^, fg- 13), and not at its extremity, as was the case m Lachrymaria. The body is ciliated over its entire surface; nevertheless the movement of some species is very sluggish, locomotion seem- ing rather to be effected by creeping and bending the body than by the exertion of the cilia. Some species are exceedingly voracious, as for example Trachelim vorax, figured by Ehrenberg, which is represented in the act of swallow- ing a Loxodes Bursaria, of which six may be seen already lodged in the interior of its body. Loxodes (lip animalcules ). These have not the neck-like appendage of the last genus, but have the upper lip dilated and hatchet-shaped. Bursaria (purse animalcules). In these the mouth is very wide and placed laterally, %vith very capacious prominent lips, but without any dental structure. They are very voracious, and although generally met with in water, some species, viz. B. Entozoon, B. intestinal is, and B. cordiformis, live parasitically in the intes- tines of the froe, toad, and water-newt. The genera Spirosto}num (snail animalcules ), Phialina ( spigot animalcules), Glaucoma ( pearl animalcules), are too nearly allied to the preceding to render any special account of them necessary. 14 POLYGASTRIA. The genus Chilodon presents a very simi- lar organisation, but is remarkable from the circumstance that its mouth is furnished with a tubular fasciculus of setaceous teeth, while the anterior part of its body is advanced forward in the shape of an expanded membrane or prolonged on one side, so as to form an auriculated appendage. In Nassula, likewise, a similar dental structure exists, but this will be best described hereafter. Nutritive system. — By employing coloured organic substances as food for these animalcules, Ehrenberg at length succeeded in developing the organisation of the nutritive apparatus in these microscopic beings. For this purpose he made use of pure indigo, carmine, sap- green, and other vegetable colouring substances which are insoluble in but miscible with water, very finely levigated, and which the animal- cules readily swallow, so that in a few minutes the coloured particles are distinctly visible in the interior of their transparent bodies. From observations conducted in this manner the following results were obtained : — 1st. That there is no absorption of the coloured fluid through the general integument of the bodies of infusorial animalcules, although this was formerly supposed to be the only manner in which they could be nourished; but, on the contrary, that they were all furnished with a special mouth and internal nutritive apparatus. 2nd. That the smallest species of Infusoria which can be observed with our instruments, even those not more than of a hne in length, have an internal set of nutritive organs as well as the largest, so that in the Monads even four, six, or eight sacculi are visible in the interior of the body, which are obviously filled through an oral aperture. In the genera Enchelis, Paramecium, and Kolpoda, moreover, an intestiniform tube was discovered traversing the whole length of the body, and opening by a distinct anal orifice. To this central canal are appended numerous blind vesicles, giving the whole apparatus the appearance of a bunch of grapes. In Para- mecium aurelia and Paramecium chrysalis Ehrenberg counted from one to two hundred of these vesicles, which became filled with blue, red, or green, according to the colouring matter employed. We have, however, already, in the prece- ding pages, described the different arrange- ment of the alimentary canal in the va- rious forms of polygastric animalcules, so that few further observations are necessary in this place. Whoever wishes to observe these little beings swallow coloured food, and thus witness the filling of the nutritive sacculi, must, in order to avoid disappointment, carefully observe that the materials he employs are per- fectly pure, the indigo, carmine, and sap green sold in the shops being generally so much adulterated that the animalcules refuse to swal- low it; secondly, that it be reduced by leviga- tion to the most extreme state of division — grinding it for a length of time with water on a slab, with a muUer, is the best way to ac- complish this. When thus prepared, by placing a little with a camel's hair brush in the drop of water which contains the animalcules, but very few minutes are required with some species to exhibit numerous vesicles filled with the co- loured substance. When filled, Ehrenberg has observed that sometimes one of them will in a short time empty itself, and its contents be suddenly transferred to another, whereby it seems as if the vesicle itself had a power of voluntary locomotion, which it has not. But however easy it may be thus to fill the stomachal vesicles, it is by no means so easy a matter to detect the central canal to which they are ap- pended, insomuch that the generality of ob- servers are quite unable to detect its presence. Upon this point Ehrenberg remarks, in reply to those who have doubted its existence, that there are only some animalcules in which it is possible to see it clearly ; and it is therefore necessary to seek out such species in order to obtain a view of it. In many it is of all things most difficult to see it ; but the cause of this does not lie in its absence, but in the nature of the functions it has to perform, for this canal, like the oesophagus of larger animals, only serves for the transmission of food, not for its retention and digestion. It becomes dilated while food is passing through it, at will, like the mouth and oesopliagus of a snake when it swallows a rabbit, and immediately collapses again, and becomes quite invisible when not actually in use. Provided the indigo and carmine employed for the purpose have been sufficiently levigated, nothing is easier than to demonstrate the presence of the stomachal vesicles; but to exhibit the central canal, and the tubes that communicate between it and the gastric sacculi, is a much more difficult task, and can only be done under very favourable circumstances. We were, in- deed, long sceptical concerning their existence; but after examining Professor Ehrenberg's pre- parations of these structures, we were ulti- mately convinced of the accuracy of his views concerning them. Whoever wishes to see the intestinal tract distinctly must examine it in large specimens of some of the following species, most of which are sufficiently common : — Chelodon cu- cullulus, Trachelius ovum, Epistylis plicatilis, Vorticella chlorostigma, Vorticella convallaria, Opercularia articulata, or Stylonychia mytilus. On putting a little indigo into the water with some of these, it may be readily seen to enter their large mouths, and pass into their stomachs, from which it is again speedily ejected. In the Monads and allied families the ali- mentary apparatus consists of several distinct cells, from eight to twenty in number, but which are not all of them filled at the same time. When contracted they are quite invisi- ble; yet sometimes, when filled with a clear fluid, they are to be distinguished under the form of minute transparent vesicles in the in- terior of the animalcule. The mouth may sometimes be easily perceived under the form of a clear transparent spot, situated at the base of the proboscis, to and from which streams of water may be seen to proceed, bringing POLYGASTRIA. 15 with them the materials for nourishment (Jig. 14). In the interior of the body the nutri- tive sacculi appear like so many little empty bags hanging from the mouth. The food of the Monads seems to consist entirely of par- ticles of decaying matter. Fig. 14. Monas quttula, highly magnified, showing the direction of the nutritive currents. Dental system. — A very remarkable dental apparatus was discovered by Ehrenberg to exist in some of these diminutive beings, their presence being recognised in several different species, viz. Euodon cvcuUus (Synonyme, Kol- poda, Loxodes cucullus ), Nassula ornata, Nas- sula elegans, Nass:da aurea, Prorodon niveus, Frorodon compressus, and others. Both in their form and connexions these teeth are very remark- able, presenting the appearance of a long slender cylinder or hollow cone, situated at the entrance of the mouth, around which they form a closely approximated series (fg. 15). These teeth Fig. 15. Dental apparatus of Chilodon ornatus. ( After Ehrenberg. ) are composed of a hard substance ; for when the soft parts of the animalcule are crushed between two plates of glass, they still remain distinctly visible, proving that they are of a denser texture than the rest of the body. Their number varies in different genera from sixteen to thirty, the former being the minimum and the latter the maximum yet observed. In animalcules thus provided with a dental appa- ratus the pharynx seems to have little to do with the act of nutrition ; indeed it frequently happens that while the little creature vibrates its cilia to produce the currents that bring it food, its mouth is kept open and motionless, so that the materials that serve for its nourish- ment pass through it unobstructed : but when larger morsels are to be swallowed, they are first seized and bruised by the dental apparatus. In this case the buccal cylinder first of all expands in front to receive the morsel; it is then narrow posteriorly : but as the aliment passes onward it becomes contracted in front and dilates behind, so as to push the food towards the mouth. Sometimes, however, these movements can be witnessed without any large morsels of food being present in the dental cylinder. While the mouth is kept open, Monads and other animalcules may frequently be seen to enter it with facility as far as the intestine ; in which case the contraction of the dental circlet seems to serve to prevent its re- turn back again, should it try to escape in this direction. A very remarkable circumstance observable in these teeth is the rapid manner in which new sets are formed as often as the fissiparous habits of the animalcules render their repro- duction necessary. This regeneration of whole sets of teeth, a phenomenon so unusual among other races of animals, is among these Infu- soria a matter of every day occurrence, a new set being produced whenever spontaneous di- vision occurs : nay, should the animalcule be mutilated so that only the hinder half of its body remains, we are assured by Ehrenberg that the missing portions will soon be repro- duced, provided with a new mouth and circle of teeth exactly similar to their predecessors; and when they spontaneously divide by trans- verse fissure, a process which occupies but a short space of time, the hinder portion, when separated, is found to be provided with a mouth and set of teeth completely organised in every respect {\,jig' 16). Sometimes, in- deed, they may be observed during this sepa- ration of the adult animal into two young ones, and the progress of the developement of the wanting parts absolutely witnessed. Under such circumstances Ehrenberg states, that such is the rapidity of the process that the division of the body, and the formation of a set of twenty new teeth, may easily be accomplished in the space of a couple of hours. Fig. 16. 1. Nassula ornata, in progress of fissure. 1. Amphi- leptiis fj^ciola. 3. Trachelocerca viridis. 4. Tra- chelocerca biceps. ( After Ehrenberg.) Mmcultir system . — In the generality of those 16 POLYOASTRIA. acrite animalcules it is almost needless to say that no muscular fibres are obvious, although their bodies are capable of various contortions, and some of their movements under the microscope are extremely brisk and active. Nevertheless, in some of the Vorticellinse, (Vorticella, Stentor, Carchesium, Opercularia,) Ehrenberg consi- ders that their presence has been detected, and has even assigned their direction, some being, as he asserts, longitudinal and others trans- vei"se. In the stems or pedicles of Carchesium and Tintinnus this appearance of muscular fibre is more especially evident ; and when we consider the highly organised condition of the genera in question, there seems to be no physi- ological reason for considering their existence improbable. Nervous .sy^^em and organs of serise. — No nervous fibrils have as yet been discovered in any polygastnc animalcule, and, in accordance with this acrite condition, no special instru- ments of sensation could, according to all phy- siological analogy, be ex-pected to exist; never- theless, in many genera the existence of one or two minute spots of a brilliant red colour is conspicuous, which are invariably found to occupy the same position in a given species possessed of them. These red spots are gene- rally pronounced to be eyes, although for what reason, except that they correspond in colour with the acknowledged eyes of some of the lowest forms of the Articulata, it is difficult to conjecture. In two species indeed, (Eu^lena longicauda cindJ?ribli/ophi/s,) Ehrenberg says he saw a " clear sharply defined ganglion," (eineo hellen, scharf umgrenzlen Markknoten,) under the red eye-spot, without, however, offering the slightest proof that the " clear sharply defined body " in question was com- posed of nervous matter. Should, however, Ehrenberg's surmises, (for these assertions are nothing more,) be correct, we should indeed encounter in the Infusoria an apparatus of vision of the simplest possible description, con- sisting merely of a brain and a coat of coloured pigment, thus dispensing both with the refract- ing media that usually constitute an eye, and the nervous communication generally found between it and the brain. Be this as it may, the Polygastria are evidently possessed of considerable perceptive power, (those without red spots quite as much so as those provided with them ;) however rapid their movements, they can steer their course with accuracy, and avoid impinging against each other ; they can likewise perceive the slightest contact, and some species, such as the Vorticellinae for ex- ample, exhibit a most exquisite sensibility of touch. Secretions. — Several species of Polygastria secrete a peculiar fluid of a beautiful violet colour, which is poured into the intestinal canal, where it colours the excrements with which it is expelled from the body. In Xas- sula ornaloy (1,./?^- 16,) the apparatus for secreting this fluid is situated at the anterior part of the body, where it is recognisable as an irregular square spot of a violet colour, situated upon the dorsal surface of the body immedi- ately opposite to tlie dental cylinder. Tliis spot is composed of a great number of little violet globules of unequal size, or, to speak more correctly, of an aggregation of c-olourless vesicles filled with a violet-coloured fluid. From this spot a canal may be traced runnincr along the back, resembling a string of pearls, in which the violet secretion is conveyed to- wards the posterior part of the body. It is only in the posterior third of the body that there seems to exist a direct union between this canal and the alimentarv- apparatus, for at this point the violet colour of the secretion becomes altered and mixed with foreign matter. In all these Infusoria the violet secretion is expelled through the anal orifice situated at the hinder part of the body, either by itself or in con- junction with the excrements. The a^ereira- tion of vesicles situated in the back the neck seems to be the secreting organ of this remarkable fluid, seeing that no vessels could be detected in communication with it, and the surrounding parts were quite transparent and colourless. Ehrenberg believes that the violet liquid, which is of a slightly viscid or almost oily character, possesses some dis- solving power, for he has noticed in the alimentarj^ canal of animalcules which con- tained a large proportion of it, that frag- ments of oscillatoriae and other substances taken as food were always discoloured, divided, or decomposed apparently by its action. Rcproductiijn. — Not the least remarkable feature in the histor\' of the Polygastria is their extraordinary fecundity, which indeed far ex- ceeds that of any other class of animals. The infusorial animalcules, constituting as they do the basis of tlie great pyramid of the animal creation, the living pasturage diffused through the waters of our globe, on which innumerable creatures have to feed, must be multiplied in proportion to the vast demand for food of this description; and, accordingly, their multiplica- tion is effected in various ways, all of which are so prolific that it becomes no longer a matter of astonishment that they swarm to such an extent in every drop of stagnant water, or that their exuviae are found in many localities accumulated in such abundance, that strata of soil and even vast rocks seem to be entirely composed of their remains. I'issiparous generation. — This mode of re- production consists in the spontaneous fissure of the original animalcule into two or more di- visions, each of which soon becomes complete in all its parts, and again divides in a similar manner. The different steps of this process, which may easily be witnessed, are m ordinary cases as follows. The body of the parent is seen, on its arrival at maturity, to become in- tersected bv a transparent line, which divides it into two equal halves. In a short time this transparent line becomes indented at each ex- tremitv, and, as the indentations become more pronounced, the original creature becomes evi- dently converted into two, which are united together by a kind of isthmus, f figs. 17 & 18 ) and at lencrth, the isthmus becoming continu- ally more and more attenuated, the slightest POLYGASTRIA. 17 effort, or the mere action of the vibratile cilia completes the operation, and the two young animalcules, thus formed, part company and commence an independent existence. The direction of the line of separation varies in different species, and even in individuals of the same species ( 1 7. 4, 5, 6, 7, 8) ; some- times it is transverse, sometimes oblique, and in other cases it traverses the long axis of the body, where the form of the animalcule is elongated or oval. This method of reproduction is ex- ceedingly prolific ; for, as each successive gene- ration arrives at maturity in the course of a few hours, and undergoes the same process of divi- sion, it will be found on computation that the progeny derived from a single animalcule may, in the course of a single month, amount to many hundred millions in number. In the Vorticellte and allied forms supported by rigid or flexible pedicles the fissiparous pro- cess is essentially similar. The adult bell {fig. 9, fl) preparatory to its division becomes considerably extended in a lateral direction {b), in which condition the line of fissure is in- dicated, extending from the mouth of the bell to the point of its connection with the pedicle. An indentation soon appears which, progres- sively extending downwards, soon separates the original animalcule into two, both of which are attached to the stem (c, d). In a short time one or both break loose; in the former case the stem survives, in the latter it perishes. The detached bells speedily assume a new form (e,f), and might easily be mistaken for a totally different genus swinnning about by means of cilia situated at both extremities of their barrel-like bodies. At last, having found a fit support, they fix themselves to it, the attached extremity becoming gradually elon- gated into a delicate irritable filament similar to that which they possessed prior to the com- mencement of the fissiparous process. Gemmipavous reproduction. — Besides the above mode of increase, many of the Vorti- cellas and similarly organized forms throw out little gemmae or lateral buds in the same man- ner as the Hydros and some other Polypes, which, as they advance to maturity, assume the form of the parent stock, from which they at length become detached, or else remain asso- ciated with the original from whence they sprung. Sporiferous reproduction. — The gastric vesi- cles of the Polygastria occupy but a small proportion of the interior of their minute bodies ; the rest is partially filled up with a granular tissue, which seems made up of nu- cleated cells, or, in other words, of sporules or spawn, the germs of future progeny ready to be called into active existence when liberated from the nidus in which they were generated. In Kolpoda cucullus {fig. 18, 3), these spo- rules are represented in the act of becoming discharged from the parent animalcul?e. In many species of animalcules it is easy, with the assistance of a good glass, to per- ceive in the interior of their bodies certain isolated sacculi endowed with very remarkable powers of contraction and of dilatation ; this VOL. IV. is repeated at regular intervals ; and so great is the contractile force that the little sac seems entirely to disappear, and then in a short time slowly dilating regains its former size. These sacculi Ehrenberg at first thought to be sto- machal cavities, which the creature could alternately fill and empty ; but subsequent observations convinced him that they were or- gans of a peculiar character. By slightly com- pressing large specimens, such as Paramecium aure/ia, he further observed that these con- tractile vesicles were generally two (sometimes three) in number, occupying determinate situ- ations in the creature's botly, and that from each of these a number (eight) of little canals were given off like rays from a centre towards the circumference of the body. These canals became gradually enlarged as the sacculus con- tracted ; and vice versa, when the vesicle dilated the canals shrunk and disappeared. Each canal is slightly enlarged at its origin from the central cavity, and the whole apparatus has the appear- ance of two little Op/iiuri, or thin-rayed star- fishes, enclosed in the body of the animalcule (fig. 18, 1 <5t 4, s, s). The contractile sacculi were seen by Ehrenberg in at least four-and- twenty different species of Polygastrica ; but the radiating canals were detected in two only, viz. Paramecium and Ophri^oglena, Fi^. 17. '1^ 1, 2. Spirostomum cirens. 3. Glaucoma sci7itilla7is. 4, 5, G, 7, 8. Glaucoma scintillans in progress of Jissiparous reproduction, sJiowing its different modes ofjissure. {^After Ehrenberg.^ These organs exhibit, both in their number and situation, important differences in different species. In Paramecium aure/ia, Paramecium caudatum, Leucophrys sanguinea, Trachelius anas, Bursaria vernalis, and Stentor ]\Iu//eri, two of them are found, one situated in the middle of the anterior, and the other in the middle of the posterior, halves of the animal. All the above species, with the exception of Stentor, multiply by spontaneous transverse division, and when thus divided each portion retains one of the contractile organs, and thehr being thus double seems to have some relation c 18 POLYPIFERA. with the kind of fissiparous division which the animalcules undergo. At certain periods four of these sacculi are met with in several of these Infusoria, whilst at others only two are found in animalcules of the same species. When four are present, there are always two situated in each half of the body, and it is remarkable 1 &4. Paramecium aardla. 2, 3. Kolpoda cucuUus. s, s, contractile vesicles ; t, testes ; o, oral opening ; a, anal opening, i^fter Ehrenberg.') that all the Infusoria thus furnished are suscep- tible both of transverse and longitudinal divi- sion, so that when so divided each quarter retains one of these organs. In Euodon ciicul- lulus three of these vesicles are present, two of which are placed one on each side of the dental cylinder, and the third in the hinder part of the body near a dilatation of the alimentary canal in the vicinity of the anal opening. This ani- malcule likewise divides both longitudinally and transversely. There is another organ regarded by Ehren- berg as playing an important part in the organi- zation of these Infusoria. This is of a roundish Fig. 19. 1 <^ ') Euplotes Clmron, exhibiting its different modes of Jissipai-ous generation. (^After Ehrenberg.^ form, but less transparent than the contractile sacculus in the neighbourhood of which it is situated, but its presence has only been de- tected in four or five species. With respect to the functions to be ascribed to the parts above described, it is by no means easy to come to any satisfactory conclusion. Ehrenberg considers that the contractile organs provided with the r radiating canals cannot be regarded as hearts because their movements are so slow ; neither can he regard them as respiratory organs, which would require the presence of a vasculai- appa- ratus more distinctly developed than it appears to be in the Polygastric animalcules ; he is, therefore, disposed to believe them to be con- nected with the generative system, and refers to them the office of fecundating the ova con- tained in the interior of the body by dispersing the seminal fluid. The opaque body above described, the same authority suggests to be the testis, believing it to secrete a seminal fluid. Both these suppo- sitions are based upon a fancied analogy be- tween the parts in question and certain organs which are met with in the Rotifera, and it is needless to say that they are at present purely hypothetical. (^T. Rymer Jones.) POLYPIFERA. — A class of Zoophytes most extensively distributed over the surface of the globe, inhabitants both of the ocean and of fresh water, and important both on account of their numbers and of the magni- tude of the structures raised by their agency. The most obvious character common to this vast race of animals is, that their mouths are surrounded by radiating tentacula, arranged somewhat like the rays of a flower ; and hence the terms Zoophyta, Phytozoa, and An- THOZOA, have been more especially appUed by naturahsts to the members of this group of living beings. So plant-like, indeed, are the forms of many genera, that the ancients regarded all the stony polypes as stony vege- talDles, or as vegetating stones, and invented many theories to explain their growth. The earlier modern naturalists thought them plants, and even Tournefort has described twenty- eight species in his " Institutions of Botany but he was the last naturahst who committed this grave error. The animal nature of the Polypes was suspected by Imperato in 1669. was proved by Peyssonel in 1727, and shortly afterwards confirmed by Reaumur and Jussieu, the latter of whom, in 1741, added them to the animal kingdom.* In order to facilitate our investigations concerning the anatomy and physiology of so extensive a series of organized beings, it becomes imperative that we should first divide them into groups, com- posed of such genera as are most nearly allied by their structure and general habits, each of which will in turn require our separate notice. Class. POLYPIFERA. Sub-class 1. Hydrozoa. Body gelatinous, free, naked, presenting in- ternally a simple stomachal cavity, which is pronded at its entrance with highly contrac- * See the History of Zooph^-tology in Dr. John- ston's admirable " History of the British Zoophytes," Lond. 1847. POLYPIFERA. 19 tile tentacular cirrhi ; without traces of viscera, and reproduced by external gemmae. Hydra (;?g. 25). Sub-class 2. Anthozoa. Mouth of polype flower-like, surrounded by contractile tentacula, the margins of which are Fig. 20. Polypes of Cydonium protruded, magnified. {After MuUer.y , a, with the tentacles expanded ; b, tentacles closed. fringed, but destitute ofvibratile cilia ; stomach forming a distinct bag, without any intestinal canal ; ovaria conspicuous, lodged in the inte- rior of the body, beneath the stomachal cavity. Family 1. — Alcyonid.^:. Polypes distri- buted over the surface of a common mass, which is polymorphous, irregular, fleshy, ad- herent, and composed of a suberiform sub- stance supported by calcareous aciculi. Alcyonium, Lobularia, Cydonium. Fig. 21. Cydonium MuUeri. (After Midler.') * Family 2. — Corallid.e. Polypes irregu- larly scattered, and more or less prominent upon the surface of a polype tree or common stem, which is arborescent, fixed by a base- ment, and composed of a solid, horny or cal- careous axis enveloped by a sort of gelatino- calcareous living cortex. Corallium, Isis, Gorgonia, Antipathes. Family 3. — Madreporid.e. Polypes in- habiting cells distributed over the surface of a stony polypary, which is fixed, and generally arborescent. The cells are small, sub-lamel- lated, and constantly porous in the intervals and in their walls (^g. 22). * Zool. Dan. tab. Ixxxi./^s. 3 & 4. Dentipora, Astraeopora, Sideropora, Stylo- pora, Coscinopora, Gemmipora, Monti- pora. Palmipora, Heliopora, Alveopora, Goniopora, Porites, Seriatopora, Pocillo- pora, &c. Fig. 22. A B A, " Madi-epore abrotanoide ; " B, a portion magni- fied. (After Quoy et Gaimard.) Family 4. — MADREPHYLLiDiE. Animals simple or aggregated (in the latter case more or less deformed by their connection with those around them), and containing in their substance a great quantity of calcareous mat- ter, forming a stony polypary, which is either free or fixed, and having a laminated surface, or provided with laminated cells. Cyclolites, Montlivaltia, Fungia (Jigs. 38, 39), Polyphyllia, AnthophyUium, Turbi- nolia {jfig. il), Turbinolopsis, Caryo- phyllia {Jig. 42), Sarcinula, Columnaria, Stylina, Catenopora, Seringopora, Den- drophyllia, Lobophyllia (fig. 23), Mean- drina (fig. 40), Dictuophyllia, Agaricia, Tridacophyllia, Monticularis, Pavonia, Astraea (fig. 43), Echinastraea, Oculina, Branchastraea, &c. Fig. 23. Lobophyllia angulosa. (After Quoy et GaimardS) Family 5. — ZoanthidjE. Polypes more or less approximated, sometimes soldered to- gether, encrusted, or solidified by foreign c 2 20 POLYPIFERA. bodies, and forming, when dried, a sort of coriaceous polypary. Zoanthus, Mamillifera, Corticifera. Fig. 24. Actinia sociata {EUis). Zoanthus (^Cuviery {After Ellis.) Family 6. — Actiniad^. Body soft and fleshy, free, mouth furnished with several rows of simple or branched tentacula. Actinia {fig. 45) Lucernaria, Moschata, Ac- tinecta, Discosoma, Actinodendron, Me- tridium, Thallasianthus, Actineria, Acti- noloba, Actinocereus, &c. Family 7. — Pexnatulid^. Animals po- lypiform, with eight pinnated tentacles, more or less prominent, and regularly arranged upon a part onl\' of a common polypary, which is free or adherent. Its form is deter- minate, and it is composed of a central axis, which is solid, and enveloped in a fleshy cortex, often of considerable thickness, and supported by calcareous aciculi. Pennatula {fig. 44), Renilla, Virgularia, Scirpearia, Pavoniaria, Veretillum, Om- bellularia. Sub-class 3. Aulozoa* (nobis). (Tubular Polypes.) Animals simple or compound, occupying the interior of corneous or calcareous tubes, which are either simple or ramified ; polypes terminal or lodged in lateral cells ; repro- duction multiform. Family 1. — Tubularid.e, Animals gene- rally aggregated ; polypes terminal, not retrac- tile ; reproduction by ova produced near the bases of the tentacula, and unenclosed in any cell ; polypary pergamentaeeous or corneous, simple, tortuous, or regularly ramified ; some- times wanting; tentacula, numerous, solid. Tubularia {fig. 48.), Endendrum, Pennaria, Syncoryna {fig. 47), Coryna, Hydractinia, Stipula. Family 2. — TuBiPORip^. Polypary com- posed of calcareous tubes, arranged in succes- sive stages like the pipes in an organ ; po- lypes terminal, with eight pinnate arms. Tubipora {fig. 52). Family 3. — Sertularid^. Polypes hy- driform, provided with simple tentacula, w hich are never ciliated ; lodged in lateral cells of various shapes and disposition, continued into the interior of the tubular polypary, which is ramified, horny, subarticulated, and fixed by a root-Hke basis. Sertularia {fig. 55), Campanularia. * ofixa,-, a pipe or reed ; C^^**, animal. Sub-class 4. — Bryozoa (Ehrenberg). Ciliobrachiata (Farre). Animals polypiform, with the tentacula around the mouth covered with vibratile ciUa, by the agency of which food is furnished to the oral opening ; aliinentarv canal com- plete, being furnished with an intestine and distinct anal orifice ; body generally enclosed in a corneous or calcareous cell ; with or without an operculum. Eschara {fig. 57), FlustraB, Bowerbankla {fig. 56 \ Pedicellina {fig. 65}, Lagunculus {fig. 61), Cristatella Mucedo. Polyps are invariably aquatic animals, some inhabiting fresh water, but the great body are marine, and most numerous in tropical seas. In very high latitudes only Cellarians, Sertula- rians, and Alcyons occur : and in the vicinity of volcanic islands in the polar seas Ccrai- lines and Gorgonians. These latter multiply a httle from 6^ to 9° N. Lat., and as they ap- proach the tropics attain their full powers of growth and multiplication. Some frequent the mouths of rivers where there is a conflux of fresh and salt water ; some love atmo- spheric influence, while others avoid it. The jnarine ones frequently plant themselves on rocks in different aspects, often regulated by the climate. They rarely expose them- selves to violent ciu-rents, or the direct shock of the waves, being generally found in the hollows of rocks and submarine caverns, and in gulfs, where the water is less agitated. HVDROZOA. The Hydree are to be met with abun- dantly in summer time in almost every pond or ditch, and may easily be collected' along with the duck-weed or other aquatic plants among wljich they reside. On filling a glass jar with the water in which they reside, and allowing it to stand for a few hours undis- turbed, the little polypes will be found, some- times in great numbers, adhering to the sides of the vessel, in which position nothing is easier than to watch their proceedings, and with the assistance of a simjile magnifier to verify the descriptions which Treiubley and others have given of the extraordinary phe- nomena they exhibit. The Hydra vij'idis, or short-armed polype, which is the species most commonly met with in this country, resembles, when expanded, a little bit of green sewing-silk, about the sixth • part of an inch in length, attached by one ex- tremity to the interior of the jar, or to any other fixed body, and having the opposite end slightly untwisted. When moderately magnified, the body of the animal is found to be a little bag open at one extremity, the opening, which is in fact its mouth, being surrounded with seven deli- cate filamentary tentacula ; while the other end is provided with a little flattened disc or sucker, by which it fixes itself to any foreign body (fig. 25). Its substance seems to be entirely composed of a gelatinous mate- rial, in which are contained numerous green- ish granular particles suspended in a glairy POLYPIFERA. 21 fluid ; and, to an ordinary observer, no fibres of any kind are distinguishable in any part oi Fig. 25. HydrcB virides in different 'stages of extension and contraction, reproducing gemmiparoiisly, attached to the roots of duck-weed, (^From Roesel.) its body : nevertheless it is highly contractile, shrinking, when disturbed, into an almost in- visible jelly-like speck, and again slowly ex- panding itself when left quiet. Incapable as such a creature would appear to be of any active exertion, this little gelatinous bag is soon found to be gifted with a capability of locomotion, which is exercised in the fol- lowing manner : whilst attached to the side of the glass by the sucker at its closed extre- mity, which forms a minute foot, something like that of a Gasteropod Mollusk, the Httle polype gradually inflects its body until some of the tentacula around its mouth are brought in contact with the supporting surface, of which they take a firm hold ; in this position it detaches its posterior sucker, and, advanc- ing it towards its head, again fixes it, and thus progresses, after the manner of a leech, by a repetition of the same manceuvres. It may, however, be easily imagined that, owing to the minute size of the Hydra, and the ex- treme slowness of its contraction, this mode of progression is by no means remarkable for its speed, and in fact a march of an inch will occupy it many hours in its performance ; accordingly the polype has been endowed with another mode of transit, of which it can avail itself at pleasure. Although its body is spe- cifically heavier than water, so that when de- tached from its hold it sinks helplessly to the bottom, it is able, when occasion requires, to row itself about in a very ingenious manner. In order to accomplish this feat, it first creeps to the top of the water, and protruding its sucker to a little distance above the surface, hollows it out into a saucer-like cavity, the buoyancy of which is sufficient to keep it afloat ; and then, supported by this curiously- contrived boat, the little Hydra rows itself about by means of its tentacula in whatever direction it chooses. No traces of nervous matter are perceptible in the composition of the Hydra, which, in its whole structure, is completely acrite ; nevertheless it is evidently able to appreciate the presence or absence of light ; for if a number of these little animals are confined in a glass vessel, one side of which is exposed to light while the other is kept in the shade, they are always found to congregate on the illuminated side, and by turning the glass round it will be found that by changing their position, they will endea- vour to regain a situation exposed to the solar influences : seeing, therefore, that they are absolutely destitute of eyes, it would seem that they perceive light by the sense of touch alone. It might naturally be supposed that a crea- ture so low in the scale of organization would be compelled to subsist upon the simplest pos- sible aliment, yet, strange to say, this little polype is carnivorous in its propensities, and is moreover gifted with such terrible powers of destruction, that animals far larger, stronger, and more active than itself fall a prey to its voracity : the Entomostracous Crustaceans, the larvae of insects, and minute Annelidans, constitute its ordinary diet, and vainly endea- vour to escape from its clutches. Whilst watching for prey, the Hydra remains per- fectly at rest, suspended by its tail, and keep- ing its oral tentacula widely spread out in difl^erent directions, nor has it generally to wait long before some of the multitudinous animals that crowd the water in its vicinity impinge against its outspread lines, when im- mediately, as if the wand of an enchanter had been laid upon it, the career of its victim is arrested; though apparently only touched, not seized, it immediately sinks motionless as though paralysed by the contact, and only after some time recovers its former vivacitv. What is the benumbing power possessed by the tentacula of the Hydra it is difficult to conjecture; some writers attribute it to a tor- pifying secretion ; others surmise the dis- charge of an electric shock ; but whatever be its nature, its effects are sufficiently potent to prevent the escape of the animal subjected to its influences. No sooner is the prey thus stricken motion- less than the tentacle against which it im- pinged begins slowly to contract and drag it towards the orifice of the mouth. It would seem that the slightest eflfbrt on the part of the animal seized would be sufficient to tear off" the almost invisible gelatinous arm of the polype, yet not more surely does the angler land a trout by means of his silken line, than the Hydra succeeds by its tenacious hold in secLU-ing its victim ; tentacle after tentacle is brought to bear upon it, and slowly it is ap- proximated to the opening of the stomach of the polype in w hich it is about to be engulphed. When lodged in thp stomach of its de- vourer, so thin and diaphanous is the distended bag of the Hydra's body, that the animal swal- lowed is still distinctly visible, and the micro- scopical observer would scarcely suspect that the pellucid film which covers it was capable of producing much effect upon its substance. Gradually, however, the swallowed prey begins c 3 22 POLYPIFERA. to lose its distinctness of outline, audits parts become dim and confused, for the process of digestion has begun, and speedily all that is digestible is dissolved, nothing being left but the hard shell and other intractable portions, which are at length expelled from the digestive sac through the same opening by which they were admitted. From the transparency of the Hydra, Trem- bley thought to be able to ascertain the man- ner in which the digested nutriment became appropriated, and observing that the polypes became coloured in accordance with the kind of food upon which they lived, proceeded to feed them with the red larvae of certain insects, in hopes of seeing how the colouring matter became diffused through their bodies, and in this he was partially successful ; the result of his experiments proving that it was through the medium of the granules floating in the semifluid transparent substance of the Hydra that the diffusion of the coloured particles was accomplished, the granules themselves assum- ing the tint of the coloured food, while the gelatinous matter in which they were sus- pended remained colourless. Another remarkable fact observed by Trem- bley was, that the digestive powers of the Hydra had no influence over the tissues of its own body, for frequently he observed that the long-armed species swallowed their own ten- tacula along with their food, the former re- maining quite intact while the latter was in process of solution, and on one occasion when two Hydrae had both of thera seized on the same prey, and were contending for the possession of it, one of them decided the con- test by swallowing the subject of dispute and his rival into the bargain. Naturally supposing that the death of the swallowed polype would be the result of such an apparently tragical termination to the dispute, Trembley was not a little surprised to see the successful polype disgorge his antagonist safe and uninjured along with the egestainenta of the meal, and to all appearance none the worse for its tem- porary incarceration. If a Hydra be divided transversely, by means of a knife or a pair of scissors, both halves not only survive, but in the course of a short time each moiety reproduces the portion of which it has been deprived, the hinder extremity developing a new set of tentacula, and the an- terior portion acquiring a sucker to replace that which was lost ; nay, it has been proved that even when divided into several fragments, eich piece retains its vitality, and in [)rocess of time regains all the characters of a perfect individual, just as the cutting of a plant speedily puts forth roots and leaves similar to tliose of the original stock from M'hich it was taken. Not less wonderful than their capability of recovering lost parts after mutilation are the powers which they possess of multiplying their species by various modes of generation. The most usual manner in which they produce off- spring is by gemmation, the nature of which, owing to the transparency of their bodies, they are admirably adapted to elucidate. The process by which this kind of reproduction is effected in the case of the Hydra is as follows. After keeping one of these polypes for a few hours well provided with food, a little bud or gemma is seen to sprout from some portion of the surface of its body, which at first seems to be a shapeless excrescence, but in the course of a short time assumes the shape of the parent animal by developing tentacula from around the oral orifice, which gradually becomes more and more distinct. For some time the newly formed polype remains attached by the little pedicle at its tail to the body of its parent, with which it seems to enjoy a sort of com- munity of existence, the food caught and di- gested by the one passing freely through a little aperture in the caudal extremity of the young polype from one to the other. At last, when the growth of the off-sprout is com- pleted, it detaches itself, and assumes an in- dependent existence ; yet sometimes even before its separation is accomplished the bud of a third generation may be observed ap- pended to the side of its body ready to under- go the same process of development. The formation of the reproductive gemmae may even be determined by extraneous causes : thus Trembley noticed that by snipping the side of an adult polype with the points of a fine pair of scissors, a bud would soon develope itself from the wounded part ; and this experi- ment might be repeated again and again, both upon the original polype and the progeny thus made to sprout from its sides, until as many as seventeen have been obtained, all con- nected with each other, and thus forming a httle tree of living polypes. Besides the gemmiparous mode of repro- duction, Hydrae have been occasionally ob- served to divide themselves spontaneously by transverse fissure, and thus separate into two animals, in the same way as some of the Poly- gastric animalcules. The anaton)y of the Hydra has been recently closely investigated by Corda, whose obser- vations upon this subject are possessed of extreme interest.* According to this observer each tentacule of the Hydra consists essentially of a long, pellucid, and extremely delicate membranous tube {Jig. 27) containing an al- most fluid albuminous substance, which in certain definite localities swells into denser wart-like knots (/;), arranged in a spiral line, along which are appended organs of touch (rf), and also instruments of prehension (c). Si- tuated within the tube, and running imme- diately beneath the above-mentioned nodosities, which are arranged in a quatcrnian series, are situated (bur longitudinal bands of muscular fibres of a slightly yellow colour (. 48. Tuhularia coronata, magnified. . a, stalk ; h, walls of the polypaiy ; c, substance common to all the indi\iduals, whereby they are brought into mutual organic communication ; d, limit between the individual and the community ; g, the long tentacles ; h, the short tentacles ; k, col- lar formed by the tentacles ; o, ova ; n, a bud ; p, a bud fiu-ther' developed ; q, a bud still further ad- vanced, showing intlications of the two rows of tentacles {g, h). {After Van Beneden.) Second mode of propagation^ hy free gemmce. — The free gemmae are produced upon dis- tinct pedicles, which in the genus Tubularia are developed within the lower circle of ten- tacula. They resemble numerous appendages disposed in a circle and forming a crown around the body of the polype, (i^/^. 48, o.) These pedicles grow in the same manner as the buds and the tentacula described above, that is to say, a hollow tubercle first makes its appearance, which seems to be merely an extension of the external covering of the polype. Each tubercle slowly expands, and soon divides into one or more branches, which are all hollow, and the same fluid which circulates in the general substance of the polype may be observed to pass into their interior. At the free extremity of each of the pedicles thus formed a distinct cell is soon perceptible, situated im- mediately beneath the surface, which cell is the rudiment of a new in- dividual, (i^/g. 49, No nucleus has been remarked in its interior. This primitive cell, which might also be regarded as an egg or as an ovule, sometimes becomes organised internally, in which case the repro- ductive process assumes the third or the fourth form, subsequently to be noticed, or else it serves for the point of departure, or it might almost be said the mould for the formation of a free gemma, which becomes organised around it at the expense of the pedicle itself. It is in effect a part of the reproductive appendage that will subsequently become detached ; but at this period of its development it is impossible to determine after which of the four modes of reproduction the embryo will be formed. The vesicle («) now increases rapidly in size, and beneath it another membrane is soon perceptible, which by its inner surface is in contact with the cir- culating fluid. This membrane is the origin of the new individual, or, in other words, a blastoderm, formed by the internal skin, and not by the vitellus. Soon there is seen, projecting from its centre,a little cone (^g. 49. 3, 4), which, compressing the vesicle («), forms a depression upon its inner surface, and the vesicle now begins to assume the appearance of a serous membrane, yielding to the pressure of the organs over which it spreads, and ultimately covers, much in the same way as the pleura covers the lungs. The tubercle (b) will afterwards form the walls of the digestive cavity, and may be seen to have the circulating fluid derived from the body of the polype moving in its substance. Around the base of the cone (b) may now be seen four other tubercles (r, 4, et seq.), which become de- ■ veloped like the preceding; but, instead of compressing the vesicle (a;, they surround it, and ultimately completely enclose it. They carry the skin with them, so as to have the appearance of a transparent vase, having four 4-t POLYPIFERA. longitudinal prominent biinds, the free edge slightly enlarged and rounded, a pedicle in the middle like the stem of the vase, and the transparent vesicle lining its interior through- out. Fig. 49. A. series illustrating the development of Tiihularia by free gemmcc, from the first indication of the bud to the time when it becomes detached. 1. A hollow tubercle or elevation, in the interior of which a movement or circulation of the glo- bules, indicated by the arrow, takes place; a, a cell just beneath the surface. 2. The same, sho-wdng the cell more advanced ; a, indicates this cell in all the figures. 3. This, and the following figures, represent the development of the gemma more and more ad- vanced; 6, a tubercle, situated beneath the cell, which becomes the stomach of the embryo ; this organ is indicated by the same letter in the other figures. 4. c, tubercles shooting up from the sides ; they are hollow, and communicate Anth the cavity of the stomach, and are the first indication of four vessels proceeding from the stomachal cavity. In the fol- lowing figures the letter c indicates these vessels. 5. b, the tubercle become more elevated, indenting the cell a ; the four secondary tubercles, c, more distinct and prominent. 6. The stomachal and its four surrounding hollow tubercles still further prolonged. 7. In this figure the four smaller tubercles have become vessels, and united with one another in front. 8. The four vessels have more completely united in front ; the arrows here, as in the other figures, in- dicate the current of the ckculatiug fluid. 9. d, The first indications of the tentacles,' con- sisting of tubercles sprouting from the four vessels. 10. The tubercles, d, at the end of the four ves- sels, c, have become sufficiently elevated to make a projection on the exterior. 11. These tubercles, become considerably salient externally, are now manifestly the four tentacles of the embryo. 12. Minute cells are now visible at the extremity of the tentacles. 13. The tentacles still more advanced ; the line of separation of the embryo fi-om its stalk become distinctly visible. 14. Hitherto the stomachal cul-de-sac has pro- gressively increased, it now begins to diminish, and the cell a, or the space between it and the external envelope becomes opened at e, forming a kind of mouth ; the embryo is now capable of great exten- sion; the pedicle is constricted at the point of insertion and its internal ca^dty nearly obhterated. (^From Van Beneden.^ The different phases of the development above described will, however, be best under- stood by a reference to the series of figures which we have appended, carefully copied from Professor Van Beneden's elaborate illus- trations. The }oung Tubularia has now assumed the appearance of a Beroe^ and in this condition has doubtless been often mistaken for an in- dividual belonging to the chiss Acalepha^ ; and lively contractions of its body are frequently witnessed, although it still remains attached to its pedicle. At the extremity of each of the four longi- tudinal vessels a little tubercle now becomes developed, which, as it becomes elongated, is converted into a tentacle, or sometimes, as in Eicdeiidrium, by its bifurcation, two tentacula are formed fi'om each tubercle. At this period of its development the young Tubularia spontaneously detaches itself from the parent stem, presenting at the moment of its separation the appearance of a balloon, or rather of a melon. (Fig. 50. \, 2, 3.) Its contrac- tions become more and more lively, and it is by the aid of these movements that its sepa- ration is effected. The two poles of its globular body may be seen to approach each other, and to separate alternately, with a movement of s} stole and diastole similar to what is observable in many Medusae. No traces of cilia are observable either externally or in the interior of its body. In this con- dition it presents an external covering, which is, so to speak, merely a derivation from the integument of the parent polype : this cover- ing presents somewhat more consistence than the internal parts, and is open in front. A second membrane lines the preceding throughout its whole extent ; Hke the former, it is quite transparent, and at the anterior opening (e) is prolonged internall}' to a little distance, forming a sort of funnel. These walls enclose four vessels (c), which extend from the base of the embryo and open in front into the hollow zone (//), from which the tentacula take their origin. These longitudinal vessels therefore conmiunicate with each other by a transverse canal, and at their origin open into the central or digestive cavity, which POLYPIFERA. 45 /ill, presently, be more particularly de- cribed. From this disposition it results that he contents of the stomach can pass as far s the extremities of these four vessels, and ly means of the transverse canal can be trans- Fig. 50. A. series illustrating the development of Tuhularia hy free gemmcE, after the detachment of the embryo from its peduncle, in continuation of that in the preceding cut. The same letters indicate similar parts in all the figures in this and the preceding series. Fig. 1. An embryo detached and mo^-ing in the ■water like a Medusa, seen in profile ; in addition to the four vessels, whose development is demonstrated in the foregoing series, eight other canals (/) are now perceptible ; these belong to the external enve- lope. 2. The same viewed obliquely, showing the situa- tion of the mouth e ; h, the transverse canal which brings the ioxur vessels into communication. 3. The same seen from below. 4. The four bands or vessels contracted a little, giving to the embrj'o a subquadrate outline ; viewed from below. The embr\'0 is now no longer spheri- cal, but flattened, as well as subquadrate. 5. The embryo viewed obliquely from above ; the sujjerior and inferior parietes drawn together ; the stomach projecting through the mouth. It now presents the fonn of a Greek cross, owing to the great contraction of the longitudinal bands or ves- sels. 6. The embryo placed inverted with respect to Fig. 1 ; the stomachal cid-de-sac, which becomes the body of the poh-pe, completely protruded. 7. An ideal transitory figure. 8. The embryo become fixed. The internal row of tentacles beginning to protrude. 9. The same more advanced. The tijorows of tentacles further developed. ^^^^yjY^ i^o^o^g*^ ferred from one to the other. Professor Van Beneden observed a fluid containing globules moving in this direction in their interior. The communication between the longitudinal ves- sels and the stomachal cavity, and their inter- communication by means of transverse canals, is another arrangement exactly similar to what exists in the adult Medusae. The outer membrane presents eight longi- tudinal canals, N\hich are found to be filled with cellules, but in which no movement has been observed. It is to the presence of these longitudinal bands that the embryo in this stage of its development owes its resemblance to certain fruits, more particularly to a melon. From the anterior part proceed four ap- pendages (f/), which were still undeveloped at the period of the detachment of the young polype, but which insensibly unfold them- selves. These are the tentacula. In the centre there projects a rounded opaque body generally of a red or yellowish tinge, which is the stomach. This viscus communicates, as has been stated above, with the four lon- gitudinal vessels, and is the only opaque part of the embryo. It opens in front b3'an orifice which constitutes the mouth ; the whole organ is eminently contractile, turning it.-elf in all directions like the body of a Hydra, sometimes elongating itself like a worm, and at others shrinking so as to be almost imper- ceptible. If the embryos examined in this condition be vigorous, their movements are very varied, and the forms that they assume extremely singular. The regular contractions above noticed are the most simple actions ; the two poles separate and approach each other alter- nately, whence results the progression of the little creature. But this contraction may be carried to a still higher degree : the rounded stomach in the middle of the embryo not only contracts itself in every direction, but it seems to turn itself in the middle of its transparent envelope like a worm in search of a passage by which to get out ; and at length it pushes its free extremity through the opening in front of it, and elongates its body still more until 46 POLYPIFERA. the two poles of the balloon becoming ap- proximated, the whole embryo becomes some- what disc-shaped, or the four vessels that communicate with the stomach (if vessels they really are), by moderately contracting, form as many depressions dividing the embryo into four lobes (^fg. 50. o, 6.), or by a more forcible contraction give it the appearance of a Greek cross, and ail these changes of form may take place in a few seconds. Observations are wanting relative to the manner in which the free embryo is con- verted into the fixed Tubularia ; for although Professor Van Beneden observed the latter at a very early period after they had become at- tached, he was unable to witness the changes that they undergo at the moment of becoming attached to some foreign body, and therefore gives a hypothetical outline of the forms through which he supposes them to pass {fig. 50.7) preparatory to their final establishment as young Tubularly (8, 9). Fig. 5 1 . A. series shou-ing tJie development of Tubularia coro- natafrom ova. 1. A ramification or bud of the ovari'. The com- mon cavity continued into it as a cul-de-sac, beyond •which is the ovum. 2. The ovum becomes much enlarged, and sur- rounding the cul-de-sac. 3. The cid-de-sac turned aside by gentle com- pression. Indentations on the o^'ujn indicating the formation of tentacles. 4. An elevation (6) in the centre of the tentacles become perceptible, which afterwards forms the proboscis-like part of the animal. 5. The same compressed between two plates of glass. 6. The embryo after its escape from the ovisac, having as yet but one row of tentacles. 7. The young animal become fixed. The short tentacles beginning to project at the anterior pro- longation or proboscis. Third mode of propagnfion, hi/ f^imple ova. — Thii mode of reproduction approximates the nearest to what occurs in the higher animals. Cells are observed to become organised in the middle of a vesicle in the same manner as the vitelline cells, and to become converted into an embryo. In this case the vitelline cells be- come aggregated and modified, so as to give rise to a new individual, which is isolated from the commencement of its existence. The point of departure for the formation of the embryo is the same as in the preceding mode of development, and the reproductive vesicle has at first precisely the same structure as in the last case, but instead of preserving its transparency, this vesicle soon exhibits nume- rous cells, which render it more and more opaque, and give it more the appearance of a vitellus. In this case moreover there is a great difference in the relations which the red pedicle {fig. 49, b) bears to the embryo. In the preceding mode of development this pe- dicle constitutes an integrant part of the newly formed being, forming, in fact, its stomach, but in the oviparous mode there is no organic connection between the one and the other, the vitellus being formed between the pedicle and the integument of the offset, and on press- ing the latter between two plates of glass these structures readily separate without any laceration. As the vitellus increases in size it becomes impacted between the integument and the pe- dicle, and its augmentation of size still in- creasing, the upper part of the pedicle becomes covered with it as with a hood, and at last almost entirely enveloped by it. At this period the margins of the vitellus become in- dented on that side nearest the pedicle, and the tubercles between the indentations soon sliosv themselves to be the rudiments of ten- tacula. The tentacula become more and more elongated, the embryo separates itself slightly from the pedicle, and a protuberance (fig- 51. 4, h) is then perceived in the centre of the ten- tacular zone, which becomes the proper body of the polype, or rather forms the walls of its stomachal cavity. The walls of the bud, which has hitherto contained the embryo, now become ruptured, and it gains its liberty {fig. 51.6). In this condition it almost exactly resembles a young Hydra in its contracted state, and in fact both its body and its tentacula seem to have the same anatomical structure as those of that simply organised polype. Having attained to this condition its development proceeds ra- pidly, and it soon begins to assume the specific form of the Tubularia from which it sprung (/a. 51.7). Prof. Van Beneden likewise witnessed the same mode of propagation in Si/ncori/na pu- silla. Fourth mode of propogatiou, hy ova with a multiple vitellus. — The fourth mode of repro- duction observed by Professor Van Beneden to occur among the tubular polypes is ex- tremely curious. In this form, as in that last described, the young individuals are deve- loped from ova, and the first steps of the pro- cess are precisely similar. A bud is formed from the surface of the parent zoo[^hyte, in POLYPIFERA. 47 the interior of which may be observed a ve- sicle that soon becomes organised into nu- merous cells, which constitute the vitelline mass exactly as in the last case. But, arrived It this point, the vitelline mass becomes tu- Derculated, assuming the appearance of a rasp- berry, and, instead of a single vitellus, it is found to be an agglomeration of several, each of which contains in its interior a Purkingean i'esicle from which a young individual is pro- duced, which is of a totally different form from its parent and covered with cilia, by the aid of which it swims freely about in search of a locality where to fix itself. This form of re- production will, however, be more particularly noticed in describing the Sertularian Polypes. Fifth mode, hy free gemmation and ova com- hined. — This last form of the reproductive process is merely a combination of two of the preceding, propagation being effected by the development of a free gemma, in the interior of which there is formed a divided vitellus. In this case a free embryo becomes organised, and takes the form of a young Medusa, accord- ing to the second mode described above, in the interior of which is contained an ovum with a multiple vitellus, from which numerous ciliated embryos are produced, as in the Ser- tularia geniculata hereafter to be noticed. TnbiporidcB . — The pol3'pary of the Tubi- Fig. 52. Tubipora musica. pora (fg. 52.)consists of several stages of cy- lindrical tubes placed parallel to each other, or very slightly diverging. These tubes are sepa- rated from each other by considerable intervals, but mutually support each other by the inter- position of external horizontal plates formed of the same dense substance as themselves, by which they are united together, so that a mass of these tubes exhibits an arrangement some- thing like that of the pipes in an organ ; whence the trivial name musica by which the species is distingu'shed. From the upper ends of these tubes the polypes are protruded, and being when alive of a bright grass green colour they contrast very beautifully with the rich crimson of the tubes they inhabit. The mouth* of the polype is suspended in the centre of the tube by means of the soft mem- brane : it is surrounded with eight tentacula, the margins of which are fringed with two or ' * Anatomie du Tubipore musical par Mons. La- mouroux. Zoologie de Quoy et Gaimard, Voyage de rUranie. three rows of fleshy papillae. Beneath the opening of the mouth is the stomachal saccu- lus, around which arise the eight ovigerous filaments. Those filaments near their origin are loose and floating, but lower down they become connected with the soft membrane {fg. 53. 1, 2,d)^ with which the tube is lined, Fig. 53. 13 2 T uhipora musica. 1, 2, longitudinal sections; 3, portion of the poly- pary, showing the connecting stage. a, membranous collar, continuous with the tube ; b, calcareous tube ; c, tentacles ; d, ovaries. throughout its whole length, but gradually diminishing in thickness as they descend. These filaments are equivalent to the ovigerous tubes of the other Anthozoa ; but the ova are here developed upon their external surface, to which they are attached by short pedicles. Extending between the roots of the tenta- cula of the polype and the margin of the tube is the membrane, which, in the retracted state of the animal, is drawn into the shape of a funnel, the mouth of the funnel being con- tinuous with the extremity of the calcareous tube. The funnel-shaped membrane is in fact a continuation of the calcareous tube, from which it only differs in texture from the cir- cumstance that the latter has become solidi- fied by the interstitial deposition of calcareous matter in its substance, while the former still retains its softness and irritability. The funnel-shaped membrane does not ter- minate suddenly upon the calcareous tube ; the latter, indeed, is a prolongation and pro- duct of it ; the calcareous substance is depo- sited in this gelatinous membrane in the same manner as j)hosphate of hme is deposited in the bones of very young subjects, changing its soft texture into hard and solid substance. The manner, therefore, in which this tube is formed cannot be compared to the mode of formation of the cells of Serpulas or the tubes of MoUusca ; in the latter it is a secretion of the skin, almost an epidermic product. In polyparies, on the contrary, there is a real change of soft into sohd substance, which is effected gradually, but the calcareous matter is not deposited in layers. 48 POLYPIFERA. We do not doubt that all polyparies, whether flexible or calcareous, are formed in a similar manner, the horny matter of one and the calcareous axis of the other being entirely produced by the conversion of soft gelatinous matter into hard substance through the agency of the membrane which always invests the polypes. Moreover, this infundibular mem- brane must offer a thousand modifications of form in different families, genera, and even species. Sometimes it is very extensive and irritable ; at others, adhering to the parietes of the cells throughout their entire length ; the polype is immovably fixed at the opening of its tube. We consider this membrane as one of the most essential organs for the produc- tion of the polypar}', having observed it in Flustraj, Sertulariae ; and, as far as we know, the same is the case in Madreporigenous polypes. When the calcareous tube has grown to a certain height, the animal proceeds to form the external horizontal stage, by means of which it becomes united to the tubes in its vicinity. In order to effect this the soft in- fundibular membrane spreads itself out hori- zontally, so as to form by its duplicature a kind of rim round the margin of the tube (fig. 2, a) ; in this state it loses the irritabi- lity that it previously possessed, and its two opposed surfaces becoming united to each other, it is gradually solidified by the depo- sition of calcareous matter in its substance, so as to form a firm horizontal plate. It generally happens that several of the neigh- bouring polypes construct similar horizontal stages at the same time, and precisely upon the same plane, in which case all the stages coalesce at their circumference, and become so intimately conjoined as to form but a single floor, which, when calcified, exhibits no marks whatever of the union which has been thus effected. After the formation of this stage the growth of the tube again proceeds up- wards, in the same manner as before, until it arrives at its full height. It is difficult to say how the ova formed upon the ovigerous filaments make their escape ; for, seeing their size, it seems impos- sible for them to jiass out by the mouth ; and it seems more probable that it is not until a |)olype dies that the germs of its progeny leave the tube of their parent, and settling down upon the horizontal stage constructed by the preceding generation commence their deve- lopment. When first attached in this position the young Tuhipore exhibits not the slightest trace of the future polype, but consists of a simple gelatinous membrane folded upon itself so as to resemble a little turban. This turban-shaped mass gradually elongates itself by its upper part, and, as its development proceeds, produces a polype in its interior, the tube which encloses it remaining soft and flexible above, while it is gradually calcified below. And it may here be remarked, that from the small diameter of the commencement of its tube, it is evident that the animal in- creases in all its dimensions during its advance to maturity. SertularidcB. — The depths of the ocean are inhabited by innumerable zoophytes equally remarkable for the beauty of their appearance and the peculiarity of their structure; these are the Sertulariae, whose arborescent stems have so much the appearance of vegetable productions that they are still regarded by the uninformed as " sea-weeds." On putting a Uving specimen of a Sertularia {fig, 54) Fig. 54. Branch of Serhdaria geniculata, magnified, showing cells, polypes, and ovigerous vesicles. into a jar of its native element, and watching it attentively with the aid of a magnifying glass, its real nature becomes at once appa- rent, and instead of being of vegetable origin, all the elegant ramifications of which it consists are found to be peopled with numbers of hydrlform polypes, all actively employed in catching prey, and apparently ministering to the support of the general community formed by their aggregation. The stem of a Sertularia consists of a hol- low tube, composed of a flexible horny sub- stance, diversely ramified in different species, in the interior of which is enclosed a soft animal substance, which constitutes the living portion of the zoophyte. At regular intervals every branch is studded with little cells, com- posed of the same horny material as the general stem, in each of which is lodged a Hydra, or at least a polype similar to the Hydra in its general characters, the base of which is continuous with the central living pith that POLYPIFERA. 49 permeates the stem, which thus seems to be nourished by the hundreds of little polypes that are constantly fishing for food. At certain periods of the year, besides the polype-bearing cells, other horny receptacles are developed, called the ovigerous vesicles {Jig. 55, h), in which the ova are produced. The ovigerous vesicles are differently dis- posed according to the species, sometimes arising from the branches of the coralline, at others from the axillae formed by their sub- divisions ; their shape likewise is very various, and sometimes they are covered with a little operculum, or lid, which closes the orifice of the vase-like vesicle during the maturation of the reproductive gemmules, and at last opens so as to permit their escape. These gemmu- liferous urns are, however, deciduous, and fall off after the development of the germs of reproduction is completed. Such being the general structure of the Sertularidae, we must now proceed to examine more minutely their intimate organisation. The stem of the Sertularian is composed of two layers, of which the exterior (Jig. 55, b), Fig. 55. Diagram of Sertularian. a, inner or nutritive layer ; b, outer or tegu- mentary layer ; c, oral tentacles of the polype ; d, e, gemmules ; /, polypiform external capsule ; h, ovi- gerous cell. or tegumentary layer, is of a dense horny tex- ture, while the internal, or nutritive layer (Jig. 55, a), is of a soft pulpy character according to the pattern peculiar to the species ; the tegu- mentary layer expands at appointed distances into the polype-cells (Jig. 55, g) ; and it is from this layer likewise during the reproductive season that the ovigerous vesicles are deve- loped. The nutritive layer (fg. 55, a), it will be seen, not only lines the stem, but likewise penetrates into the polype-cells, where it be- comes continuous with the body of the con- VOL. IV. tained polype, the structure of which closely resembles that of the Hydra ; it seems, in fact, to consist of nothing but a stomachal sacculus, the mouth of which is surrounded with con- tractile tentacles, which are never, as errone- ously stated by some writers, provided with vibratile cilia, such as are possessed by some more highly organised polypes. The nutriment elaborated in the digestive sacciili passes into the central cavity of the stem, in which an evident circulation of globules is apparent, somewhat analogous in its appearance to what is perceivable in the Chara and other transpa- rent vegetables. It is from the nutritive layer which lines the ovigerous vesicles likewise that the repro- ductive gemmules are developed. These (^g. 55, d), as they gradually become separated from the nidus in which they are formed, retain their connection with the vital tissue of the nutritive layer, by the intervention of a kind of umbilical cord, until they are suffi- ciently matured to allow of their escape. When this period arrives each gemmule is found to be covered over with vibratile cilia, by the action of which it detaches itself from the umbilical filament, and, escaping from the reproductive cell, swims away into the sur- rounding element. Here, by means of its cilia, it swims about, having much the appearance of a polygastric animalcule, until it finds a fit locality for its development, when it settles down, and, losing its locomotive organs, spreads out like a film of jelly upon the supporting body. The formation of its horny envelope then begins, fibres of which are first extended like the spreading root of a tree, so as to give a firm hold upon the basis for support ; and then the stem itself begins to shoot upwards, deve- loping, as it ascends, the nutritive polypes and the horny cells in which they are individually lodged. In order to understand how growth is ac- complished in these tube-clad zoophytes, it will be necessary to refer once more to the preced- ing diagram (Jig. 55) . The tegumentary layer of the zoophyte (^g. 55, b) is at first quite soft and expansible, the hard corneous matter by which it is consolidated being afterwards superadded to its texture. Whilst growth is in progress, therefore, this outer layer shoots upwards in conformity with the pattern to which it belongs ; but whilst the top of the tube retains its softness and power of growth it is continually fortified below by the depo- sition of the horny matter which gives it solidity : growth can therefore only proceed at the extremity of every branch where this layer remains capable of further development ; for no sooner is it solidified than it remains permanently unchangeable. Hence it is that these zoophytes differ so remarkably from plants in the character of their arborescence : in the latter the stem is increased by constant additions to its thickness, but in the case of the Sertularia no such thickening is possible ; so that both stem and branches retain the sa^ne diameter throughout, however much their 50 POLYPIFERA. ramifications may be extended. As the growth of the tegumentary layer thus proceeds in one direction only, except when the development of polype-cells calls for its lateral expansion, the nutritive layer within continues to grow pari passu, and from it the polypes are pro- duced as the cells become ready to receive them. Bryozoa (Ehrenberg), Ciliobrachiate Polypi (Farre). — The Bryozoa, although closely resembling some of the simpler Poly- pifera, described in the preceding pages, with which, indeed, until a very recent period, they were confounded by zoological writers, differ from them in so many essential points of their structure, that, but for the convenience of description, we should have preferred to re- gard them as a distinct class, exhibiting a much higher phase of organisation than any of the nudibrachiate races. In all the fami- lies of Polypifera we have as yet had occasion to examine, it will have been noticed that the tentacular apparatus around the mouth, al- though very generally pinnated, are quite devoid of cilia ; but in the Bryozoa one of the most obvious circumstances observ- able in their organisation is, that all the circumoral arras are crowded with \abratile organs, the play of which, when in action, is exceedingly energetic, producing rapid cur- rents in the surrounding water, and thus hurrying towards the mouth of the animal whatever substances may come into the neigh- bourhood of the vortex so produced, and in this way secm'ing an abundant supply of food, almost without exertion on the part of the creature itself From this most conspicuous character, common to the entire group. Dr. Arthur Farre was induced to propose for them the name of CUiobrach'mta. It is in their internal economy, however, that their chief points of distinction are to be sought. Like the ordinary polypes, most of these little animals inhabit cells of different shapes and various degrees of density. These cells are sometimes calcareous and opaque, but in very many genera so thin and diaphanous that nothing is more easy than to examine, by means of the microscope, the anatomy of the animal within. When thus examined, the differences between a Bryozoon and an ordi- dinary polype become immediately manifest, and may be briefly stated as follows. In the nudibrachiate polypes the stomach is a simple sacculus unprovided with any intestinal tube or anal orifice, so that after taking food the egesta are necessarily ex- pelled through the oral opening ; but in the Ciliobrachiata, not only is the stomach found to be floating loosely in a visceral cavity, and of very complete structure w^hen compared with the digestive sacculus common to the pre- ceding tribes, but it terminates in a complete intestinal canal, provided with a distinct anal orifice, through which the faeces are discharged. Accompanying this advanced condition of the alimentary apparatus all the other systems assume a more elevated type of structure, as will be immediately apparent from the details of their anatomy, upon the consideration of which w^e are about to enter. Much, doubt- less, yet remains to be made out in the eco- nomy of these animals ; still the researches of Ehrenberg*, Milne Edwards, Audouin|, Thompson j, Farre §, and Van Beneden |1, have already put us in possession of most important inforniation concerning them, which promises to open a yet wider field for discovery. The cell of Bowerbankia {fig. 56), as de- Fig. 56. Bowerbankia densa, magnified 80 diameters. a, one of the animals fully expanded ; 1, pharjTix ; 2, cardia ; 3, manducatory organ, or gizzard ; 4, sto- macli, its parietes studded with the hepatic follicles ; 5, pvlorus ; 6, intestine, containing pellets of feculent matter ; 7, anus. The gastric (8) and tentacular (9) retractors are seen -within the caAity of the body. The flexible portion of the cell, or the operculum, is seen expanded and surroimding the upper part of the body. b, a similar animal completely retracted. The stomach drawn to the bottom of the cell. The upper portion of the alimentary canal flexed. The tentacula somewhat distorted by the pressure of the operculum. Their retractor filaments (1) relaxed. The upper part of the cell is occupied by the oper- culimi folded up in its axis, and from it the upper (2) and lower (3) sets of opercular retractors are * Spnbolfe Physicae. t Annales des Sciences Xaturelles, for Sept. 1828, and July 1836. X Zoological Researches, Mem. V., Cork, 1830. § Phil. Trans, for 1837, part 2. Jl Recherches sur I'Anatomie, la Physiologic et rEmbryogenie des Bryozaires. 4to. Brussels, 1845. POLYPIFERA. 51 seen radiating, and in their contracted state. These tilaments are about , ' _ inch diameter in this state. 6 .5(J0 c, An immature animal. The tentacula and aU- mentary canal rudely formed; the cavity in the latter very distinct. The tentacular and opercular retractors also shown ; 1, the gizzard. d, one of the gemmaj in its earliest state. The cavity just defined, but no animal distinguishable. (^After Farre.~) scribed by Dr. Arthur Farre, is cylindrical, and closely embraces the body of the animal ; it is of a firm unyielding consistence in the lower two-thirds of its extent, but terminates above by a flexible portion, which serves to protect the upper part of the body when the whole is expanded, in which state it is of the same diameter as the rest of the cell ; but when the animal retracts, this portion is folded up and drawn in after it, so as to close its mouth. The flexible part consists of two portions, the lower half being a simple continuation of the rest of the cell, the upper consisting of a row of delicate bristle-shaped processes, or setae, which are arranged parallel with each other round the top of the cell, and are prevented from separating beyond a certain distance by a membrane of excessive tenuity which sur- rounds and connects the whole. This arrange- ment is common to all the species possessing a cylindrical cell ; but the length of the setae is very variable ; indeed they are sometimes so stunted in their development that their pre- sence is hardly recognisable. The cells of the FlustrcE and Escharce are disposed side by side upon the same plane, so as to form a broad leaf-like polypary, which is in the former genus of a coriaceous or horn^ texture, but in the latter so completely calci- fied as to resemble the skeletons of the Litho- phytous Polypes. The individual cells (Jig. 39), which are so extremely minute that they Fig. 57. Eschara cervicomis, natural size. (After Milne Edwards.^ require a microscope for their examination, vary in shape in different species, and gene- rally have their orifices defended by project- ing spines, or sometimes by a movable oper- culum or lid, which answers the same purpose as the setae of lioircrhmJda, by closing the entrance during the retracted ' state of the animal. The growth of these pol}'[)aries, which are thus densely populated, is effected by the progressive addition of new cells aroimd the circumference, those occupying the margin being of course the most recently formed, and, indeed, the latter are not unfre- quently found inhabited by the living animals, whilst in the older or central ones the original occupants have perished. A polype of Eschara cervicomis highhj magnified. a, tentacula ; h, first digestive cavity, which seems to be analogous to the respiratory cavity of the com- pound ascidians ; c, filaments arising from the part of the alimentary canal immediately below this ca- vity ; d, stomach ; e, intestine ; f, anus ; g, retractor muscles. (After Milne Edwards.) The facts observed by Dr. Milne Edwards * relative to the mode of formation of these cells possess a high degree of interest, and materially support the views already given concerning the organised nature of the skele- tons of zoophytes in general ; proving that the calcareous matter to which their hardness is owing is not a mere exudation from the surface of the animal, but is deposited in the meshes of an organised tegumentary mem- brane, from which it can be removed with facility by means of extremely dilute muriatic acid. When so treated a brisk effervescence is produced, the cells become flexible, and are easily separated from each other; but they are not altered in form, and evidently consist of a dense and thick membrane, forming a sac, in which the digestive organs of the ani- mal are contained. In this state the opening of the cell has no longer a defined margin, as it seemed to have before ; but, as in the case of the Tubipora musicay described in a pre- ceding page, the membranous cell is found to be continuous with the tentacular sheath. We see, therefore, that in these creatures the shell is an integrant portion of the animal itself, not a mere calcareous crust moulded upon the surface of its body, being, in fact, a * Recherches anatomiques,' zoologiques, ct phy- siologiques sur les Eschares; An. des Sc. Nat. for 1836. E 2 52 POLYPIFEHA. portion of the tegumentary membrane, which, by the molecular deposit of earthy matter in its tissue, becomes ossified, something like the cartilage of the higher animals, with- out ceasing to be the seat of nutritive move- ment. It is evident likewise that what is usually called the body of the Bryozoon constitutes, in fact, but a small portion of it, principally consisting of the digestive appa- ratus. As to the operculum, destined to close the entrance of the tegumentary cell, it is merely a hp-like fold of the skin, the marginal portion of which acquires a dense consistency by in- terstitial deposit, while at the point where it is continuous with the general envelope it remains sufficiently soft and flexible to form a sort of hinge. The tegumentary sac, deprived of its car- bonate of lime, seems to be formed of a to- mentous membrane, covered, especially upon its inner side, with a multitude of cylindrical filaments, disposed perpendicularly to its sur- face, and closely crowded together. It is in the interstices left by these fibres that the calcareous matter appears to be deposited; for if a transverse section be examined with the microscope the external wall is seen not to be made up of superposed layers, but of cylinders and irregular prisms arranged per- pendicularly to the axis of the body. But the above are not the only arguments adduced by Milne Edwards in proof that these polyparies are maintained in vital connection with the animal. On examining the cells at different ages it is found that after they are completely calcified they undergo material changes of form. This examination is easily made, seeing that in many species the young sprout from the sides of those first formed, and do not separate from their parents ; each skeleton, therefore, presents a long series of generations linked to each other, and in each portion of the series the relative ages of the individuals are indicated by the position which they occupy. It is sufficient, therefore, to compare the cells situated at the base, those of the middle por- tion, those of the young branches, and those placed at the very extremities of the latter. When examined in this manner it is seen that not only does the general configuration of the cells change with age, but also that these changes are principally produced upon the external surface. For instance, in the young cells of Eschara cervicornis, the subject of these observations, the walls of which are of a stony hardness, the external surface is much inflated, so that the cells are very distinct and the borders of their apertures prominent ; but by the progress of age their appearance changes, their free surface rises so as to extend beyond the level of the borders of the cell, and defaces the deep impressions which marked their respective limits. It results that the cells cease to be distinct, and the polypary presents the appearance of a stony mass, in which the apertures of the cells only are visible. Fig. 59. Portion of a branch of the polypary of Eschara cer- vicornis, viagnified 20 diameters to show the form and arrangement of cells. (^After jyiilne Edwards.') Muscular system. — The muscular system of Bowerbankia is described as follows. For the process of retraction two distinct sets of muscles are provided ; the one acting upon the animal, the other upon the flexible part of the cell. The muscles for the retraction of the ani- mal are contained in the visceral cavity, and consist of two bundles of delicate thread-hke chords {Jig. 56, 8 and 9) ; the one set, arising from the bottom of the cell, to be inserted about the base of the stomach ; the other, also arising from near the bottom of the cell, though generally at the opposite side from the former, and passing up free by the side of the pharynx, to be inserted around the line of junction of this organ with the base of the tentacula. The muscles provided for the retraction of the opercu- lum, or flexible portion of the cell, have their origin from the inner surface and near the top of the stiff" part, and are inserted into the flexible portion on which they act. They are most distinctly seen when the flexible operculum is completely drawn in, at which time the latter is folded up so as to occupy the axis of the upper part of the cell, and to it the muscles are seen extending from the oppo- site sides of the cell from which they have their origin. They consist of six flattened bundles of fibres, having a triradiate arrange- ment. The upper three sets {fig. 60, a, 3) act upon the upper part of the cell, and are in- serted into it. The low er three {fig. 60, c, 4) are smaller, and are for the purpose of re- tracting the bundle of setae with which it is crowned. These fasciculi afforded Dr. Farre an ex- cellent opportunity for investigating the struc- ture of this form of muscle. It would appear as if muscular fibre were reduced to its sim- plest condition. The filaments are totally disconnected, and are arranged the one above the other in a shigle series. They pass straight and parallel from their origin to their inser- tion, and have a uniform diameter through their whole course, except that each filament generally presents a small knot upon its centre, which is most apparent when in a state of contraction, at which time the whole filament also is obviously thicker than when relaxed. POLYPIFERA. The filaments have a watery transparency and smooth surface, and under the highest powers of the microscope present neither an appear- ance of cross-markings, nor of a hnear arrange- ment of globules. These muscles, though apparently attached to the inner walls of the cell, must yet have the membranous parietes of the body interposed between their inser- tions and these walls. In the lower part the integument is only occasionally seen separate from the walls of the cell, but above it may be easily discerned in the expanded animal, passing up to be inserted around the tenta- cular ring, and thus distinctly bounding this part of the body, which is always free within the expanded operculum. The operation of this mechanism in retract- ing the animal within its cell is as follows. The tentacula, from being expanded in the form of an inverted cone, are brought together into a straight line, and immediately begin to descend (^Jig. 60, d). Their descent is Fig. 60. Boicerbanhia densa. magmfied 80 diameters. A series to show the mode in which the opercidum and upper part of the body is unfolded. The same animal is represented in four different stages. a. First stage : the top of the cell completely closed; the seta^ folded up in the centre (1), with the flexible portion of the cell (2) inverted and closely siirroxmding them ; the muscles contracted (3, 4.) b. Second stage : the bvmdle of the setae (1) rising from the centre of the cell being forced up- ward by the pressure of the tentacula ; the flexible portion (2) rolling from aroimd the setae, and the muscles (3) put upon the stretch. c. Third stage ; the flexible portion (2) completely everted; the setie (1) still hang together; the tentacles just appearing between them. d. Fourth stage : the tentacula appearing above the margin of the operculum ; the integument of the body, which forms the tentacular sheath, half everted (3) ; the operculimi completely expanded. (These stages are taken arbitrarily, the process being continuous.) The animal is sho'wn completely extended at fig. 56, a. {After Farre.) effected by the contraction of the muscle (Jig. 56. 9) which passes from the base of the cell to the tentacular ring, whilst at the same time the stomach is drawn down by its retractor (fg. 56. 8). The whole body, how- ever, does not descend in a mass, but must be folded up in a somewhat complicated manner, in order that the cell may completely enclose 53 it. For this purpose the oesophagus sur- mounted by the tentacula descends first, whilst the integument of the upper part of the body begins to be inverted at the point where it has its insertion around the tentacular ring. As the descent of the tentacula proceeds, the inversion of the integument continues forming a sheath around them (Jig. 60, c), until the extremities of the arms have descended to a level with the top of the unyielding portion of the cell. The animal is now drawn com- pletely in, the stomach brought close to the bottom of the cell, and the oesophagus bent in the form of the letter S ; the tentacula lying straight in the axis of the cell, enclosed in their tegumentary sheath, and so sepa- rated from the fluid in the general visceral cavity, the centre of wdiich they have the appearance of occupying, while in fact they are external to it. The animal being thus re- tracted, the next step of the process is to draw in the upper lutrt of the cell after it. This process, however, always commences before the retraction of the body is com- pleted, and by the time that the ends of the arms are on a level with the base of the setae, the latter are brought together in a bundle, and begin to descend apparently by the action of the lower of the two sets of opercular retractors above described. Their descent, like that of the tentacles, takes place exactly in the axis of the upper part of the cell, and is accompanied by an inversion around them of its flexible portion, similar to that of the integument of the body around the tenta- cula during their descent (Jig. 60, b). Whilst the lower set of muscles are drawing down the setce, the upper set complete the retraction of the flexible part, and the whole operculum is thus packed closely in the upper part of the cell, the end of which now presents a triangular indentation, corresponding with the triangular arrangement of the opercular re- tractors (fig. 60, a). Thus the whole pro- cess of retraction may be easily accounted for, and the office of each set of muscles satisfactorily explained ; but the protrusion of the animal is effected by a totally different mechanism, viz., by the action of a set of transverse muscles acting upon the lining membrane of the cell, so as by their contrac- tion to diminish considerably the diameter of the visceral cavity, and consequently exercise a pressure upon the fluid which it contains. The effect of this will be to elongate the body in the direction in which it is most free to move ; but Dr. Farre supposes that the act of protrusion is materially assisted by the co- operation of the alimentary canal, which un- doubtedly has the power of straightening itself from the sigmoid flexure into which it is thrown when the animal is retracted ; and that this is the case appears the more pro- bable, when we reflect that in the case of the simple hydriform polypes the advance and receding of the animal in its cell is entirely effected by the action of the parietes of the body, which are analogous to the alimentary canal in the present case, the hvdriform po- E 3 54 POLYPIFERA. lypes possessing no distinct muscles to assist in these operations. In some species of Bryozoa there are only two sets of opercular muscles, whilst in others one set only is perceptible. Alimentary system. — In Bowerbankia the whole alimentary apparatus has been minutely described and figured by Dr. Farre.* The ten- tacula are united together at their base to form a circle, in the centre of which is the mouth, and from which descends the oeso- phagus, bulging a little at its commencement, and then contracting and passing down nearly straight to its termination. The parietes of the oesophagus, especially at the upper part, which may be more correctly denominated the pharynx {fig. 56, a, 1), are thickly studded with minute oval spots, arranged closely in contact with each other. The whole organ appears to be highly irritable, and contracts vigorously when food is intro- duced into it. At the termination of the oesophagus is a small distinct cardiac orifice {fig. 56, a, 2) opening into a smali globular cavity (.3), of singular construction, that appears to perform the office of a gizzard, the parietes of which are thicker than any other part of the ali- mentary canal. This gizzard contains two dark round bodies, placed opposite to each other, from each of which dark lines are seen radiating. In the space between these two dark bodies may be seen a number of squami- form spots, arranged closely in contact, and presenting a beautifully regular tesselated appearance, which, on minute examination, is found to consist of a pavement of gastric teeth. The gizzard opens downwards into the true digestive stomach (4-), an oblong cavity terniinating below in a blunt extremity. The entire walls of the stomach are thickly studded with spots of a rich brown colour. These appear to be hepatic follicles, and to prepare a fluid that tinges the whole organ, as well as its contents, of a rich brown hue. From the uj)per part of the stomach, and by the side of the entrance from the gizzard, arises the intestine (6) by a distinct pyloric orifice (5) that is surrounded by vibrating cilia. The intestine is narrow, and passes up straight by the side of the oesophagus, from which it is entirely separate and free, and terminates by a distinct anal orifice in the delicate parietes of the body, close to the outer side of the tentacular ring. The pari- etes of the intestine are marked with f)ale spots, and, like those of the whole of the alimentary canal, possess a high retractile power. The animal, when in full vigour, is seen projecting from its cell with the arms extended and the cilia in active operation, the upper part of the body being frequently turned from side to side over the edge of the cell, tiie extremity of which, from its peculiar flexibility, moves with it. The particles carried to the mouth by the action of the cilia, after remaining a * Loc. cit. little while in the pharynx, are swallowed by a vigorous contraction of its parietes, and carried rapidly down the oesophagus and through the cardia into the gizzard, which expands to receive them. Here they are submitted to a kind of crushing process, the parietes of the organ contracting firmly upon them, and the two dark bodies being brought into apposition. Their residence, however, in this cavity is only momentary, and they are immediately propelled into the true stomach below, where they become mixed with its contents, which, during digestion, are always of a rich brown colour, being tinged with the secretion of its parietal follicles. The food appears to be retained for a con- siderable time in the stomach, and may be seen to be frequently regurgitated into the gizzard, whence, after having been again sub- mitted to its operations, it is returned to the stomach. Here it is rolled about by the con- tractions of its parietes, and at its upper part is frequently .submitted to a rotating motion. This rotation of particles is chiefly near the pyloric orifice, and a mass may be often seen projecting through the pylorus into the intes- tine, and rotating rapidly in the direction of the axis of the orifice. This rotation is ef- fected by the action of cilia surrounding the pyloric orifice, which, in very transparent specimens, are distinctly visible with high powers of the microscope. The granular matter, after rotating for some time at the pylorus (a provision for prevent- ing its too rapid escape from the stomach), passes into the intestine, where it accumulates in little pellets that distend the parietes of the tube, and it is possible that it may here be still further acted upon by these parietes which have a spotted appearance. By the contraction of the intestine the little pellets of excrementitious matter are carried rapidly upwards to the anal orifice, which is seen to open and the little pellet to be tilted over its edge, when it is immediately whirled away from the sight in the current produced by the cihated tentacles, and the orifice of the tube again contracts. The general character of the alimentary canal appears to be similar in all the cilio- brathiate polypes, but in ^many genera the gizzard does not exist. The anatomy of the animals inhabiting the cells of Fliistrce and Escharcs differs in some particulars from that of Bowerbanlda. In these, the crown of ciliated tentacula is in- serted into the extremity of a kind of pro- boscis, which is itself enclosed in a cylin- drical retractile sheath. From the mar- gin of the opening of the cell arises a membrane equalling in length the contracted tentacles, and serving to enclose them when the animal retires into its abode. The ten- tacula when thus retracted, as was the case in Bowerbankia, are not bent upon them- selves, but are perfectly straight and united into a fasciculus, the length of which, however, is much less than that of the same organs when expanded. POLYPIFERA. 55 By the opposite extremity to that which is derived from the margin of the cell, the ten- tacular sheath unites with a tolerably capa- cious tube, the walls of which are exceedingly soft and delicate, and near the point of their union we may perceive a fasciculus of fibres running downwards to he inserted upon the lateral walls of the cell. These fibres ap[)ear to be striated transversely, and are evidently muscular ; their use cannot be doubted. When the animal wishes to expand itself, the mem- branous sheath above referred to becomes rolled outward, everting itself like the finger of a glove as the tentacles advance. The muscular fasciculi are thus placed between the everted sheath and the alimentary canal, and by their contraction they must necessarily retract the whole within the cell. The first portion of the alimentary canal {Jig. 5S,b) is inflated, and much wider than the rest ; it forms a kind of chamber, in which the water set in motion by the ciUa of the tentacles ap- pears to circulate freely. The walls of this chamber are exceedingly delicate ; the soft membrane forming them is puckered, and ap- pears traversed by many longitudinal canals united by minute transverse vessels ; this appearance, however, may be deceptive. Beneath the first enlargement, the digestive apparatus becomes narrower, but immediately expands again, and offers at this point a cer- tain number of filifoim appendages (c), which appear to be free and floating in the interior of the cell. To the second cavity succeeds a nar- row canal opening into a third dilatation, gene- rally of a spherical form (d). From the last- named viscus issues a kind of intestine, which soon bends upon itself and becomes attached to an organ of a soft and membranous tex- ture, having the appearance of a caecum, and which seems to be continuous superiorly with the digestive tube. The latter continues its progress towards the upper part of the cell, and ultimately terminates by a distinct anal aperture upon the upper aspect of the ten- tacular sheath. The operculum which closes the cell in Flustrae and Escharse is moved by two muscular fasciculi inserted into the in- ternal face of this valve by the intermedium of two filaments analogous to tendons ; by their inferior extremity these muscles are attached to the walls of the cell, and when, by its own elasticity, the operculum is turned back, and the mouth of the cell thus opened, they by their contraction can close it like a door. Reproduction. — The first mode of repro- duction observed in the Ciliobrachiate pol\ pes is by a process of gemmation from the com- mon stock or creeping stem upon wdiich the animals grow. This is easily witnessed, as the gemmae are met with in every progressive stage of development upon the same specimen, as represented in Jig. 65. The smallest gemmae are described by Dr. Farre as homogeneous in their texture, form- ing little nodules on the parent stem. Those further advanced were seen to present some- thing like a boundary fine, indicating the thickness of the parietes of the future cell. Within this, in others, was a dark mass, which in larger ones presented a rough outline of the form of the complete animal. Those about half grown had all the parts distinctly traced out ; the retractor muscles completely formed ; the tentacles short and clumsy ; the walls of the alimentary canal thick, and its boundaries clearly defined. This mode of propagation has been still more completely studied by Professor Van Beneden, whose opportunities of observation enabled him to prosecute the inquiry more closely. In PediccUina the phenomena attending the gemmiparous mode of reproduction are de- scribed by Professor Van Beneden as present- ing the following phases of development. First, there sprouts from the common stem of the Bryozoon, without any determinate situation, a tubercle which is but a prolongation from the stem itself {Jig. 65, a, 8) ; this tubercle extends outwards, becomes more prominent, and soon swells out into a vesicle {h, 8), which is' the first appearance of the new individual. Up to this period the interior of this vesicle, is like that of the stem itself, of which it is only an extension ; but now a cellule becomes visible in its centre, which Ibrms the point of departure whence the development of the embryo proceeds. Around this primitive cell a series of other very small cellules soon group themselves, which seem to constitute the parietes of the primitive vesicle or the blastoderm, the original cell representing the vitelline cavity. The bud enlarges, and as its growth proceeds the internal tissue becomes thickened, so as to fill it ; subsequently an indentation is appa- rent on each side of the little cavity which separates it into two halves, the inferior of which will form the stomach, properly so called, while the upper division will become the anterior space between the tentacula. The mode of reproduction by gemmae has been carefully studied in the genus Lagiincida {Lagenella of Farre) by the same investigator. The reproductive buds sprout from the creep- ing stems {Jig. 61, y) which connect the indi- vidual animals, appearing at first as a slight prominence, that soon expands into a rounded tubercle, which is the commencement of a new cell. On close inspection, this bud is found to consist of a transparent envelope, which is, in fact, a continuation of the general invest- ment of the polype. This rudimentary cell is lined throughout with a soft membrane, having its inner surface studded with minute globules, b} the accumulation of which the polype is ultimately formed. The bud itself is hollow, and communicates with the parent stem. It therefore has nothing in its composition re- sembling that of an egg ; neither distinct vesi- cle nor vitellus ; this condition of the gemma is represented in fg. 6'2. 1. The new- formed cell soon grows taller, and its lining membrane becomes thicker, and indicates the commencement of the intestinal canal, which is at first a simple ca\ity, bounded by the E 4 56 TOLYPIFERA. thickened lining membrane of the cell. This cavity once formed, the development of the different organs proceeds rapidly. First, in the middle of the cavity there appears a longi- tudinal fold resembling two lips {fg. 62. 2), which, as they approach each other, divide the cavity of the body into an anterior and a posterior compartment. The two lips, which have a valvular appearance, become indented very regularly along their margins, and are soon recognisable as the rudiments of the tentacular circle (_/?g. 62 3). At this epoch, it must be remarked, the polype presents two cavities distinct from each other. There is a space between the ■walls of the body and the parietes of the Fig. Gl. Laguncula repeiis, mag/iijied 4.00 dicuneters. A. The animal completely retracted into its cell ; B, another individual completely expanded ; C, the outlines of another individual retracted. The same letters appl}' to each of the ligures. The various viscera are situated in different planes, but are here represented all in the same. a, the tentacles, protnided and expanded in B. ; the arrow indicates the set of the currents caused by the vibration of the cilia ; b, buccal cavity ; c, valve separating this cavity from the oesophagus ; d, oesophagus ; /, pyloric valve ; g, cilia, producing the notation of the food in the stomach ; ft, thickness of the parietes of the stomach ; ?, intestine ; k, ex- crement contained in its interior ; /, anlis ; m, testicle ; n, ovarj- ; o, ovum escaped from the ovarA* ; p, aper- tures through which the eggs are expelled, vriih an ovmn in the act of escaping , q, spermatozoa, freed from the testicle, and floating in the fluid that stir- romids the digestive canal ; r, s, t, u, v, muscles, re- tractors of the parts to which they are attached ; w, principal retractor muscle ; .r, transverse folds of the collar ; y, bands, perhaps muscular, of the collar ; «, nervous oesophageal ganglion ; ^, stalk ; y, a young bud. (^Aftei Vaji Bencden.) POLYPIFERA. 57 future alimentary canal, the interspace being in communication with the stem of the parent polype, and filled with a fluid that is analogous to the blood of the higher animals ; superiorly this cavity likewise penetrates into the ten- tacles, and the fluid which bathes the exterior of the alimentary canal thus finds admission even to the extremities of those organs (/g. 62. 6,7»). F,g. 62. Development by buds of Laguncula repens. 1. A young bud, Avith the cavity of the stalk ex- tending into it, the parietes thickened at one part ; it is from this part that the intestinal canal and tentacles are formed. 2. A sac is formed in the interior, having a longi- tudinal fold, which afterwards becomes the tentacles. 3. The rudiments of the tentacles are here appa- rent : the view is taken so that the space which they siu"round is visible. 4. In this figure all the organs of the animal can be distinguished, but the bud is not yet opened. 5. Here the cell is opened, and the animal is ready to expand itself. 6. Section of the adult animal ; a, tentacles ; b, mouth ; c, buccal cavity ; d, valve separating this cavity from the oesophagus ; e, oesophagus ; f, sto- mach; g, pyloric cilia; h, pyloric valve; i, intes- tine ; k, anus ; I, peri-intestinal cavity ; m, commu- nication of this cavity "with the interior of the ten- tacles ; n, nervous ganglion ; o, long retractor muscle ; p, retractor of the stomach ; walls of the cell. (^After Van Beneden.) The second cavity, which is the intestinal, has as yet no communication with the ex- ternal world. As the formation of the ten- tacula proceeds, the portion which is situated in front of them will become the sheath, and the other part the proper intestinal canal j the former cavity is, therefore, in all respects comparable to that which exists in the Tuni- cata situated in front of the proper oral orifice and lined with the branchial vessels. The tentacles of these polypes, in fact, if connected by transverse canals and attached to the sheath, would transform the ai»imals in this phasis of their growth into Ascidians. As the tentacula are formed by the pro- longation of the tubercles which were their first rudiments, the cavity of the stomach and the rest of the intestinal tube gradually be- come apparent, and at the same time some globules are visible disposed around the cul- de-sac of the former viscus, which gradually become arranged into fibrillae, and constitute the retractor muscles. At what time the nervous system is formed could not be detected. When the cell has nearly reached it? full development, the tentacular sheath is com- pleted in the same proportion, the parietes of the cell become softened, and an opening is formed which brings the young polype into communication with the surroundmg element. The Bryozoon has now attained its full deve- lopment, and can expand its tentacula, but as yet there are no traces of the reproductive organs, which seem to be formed after all the others. In Halodaciylus reproduction by gemma- tion is effected by the development of young animals and cells amongst the mature ones. The newly formed cells are triangular, and the animal looks like a mere spot in their centre. As they grow they thrust aside the surrounding cells, and the number of their sides increases until they acquire the regular hexagonal form of the adult. The Halodaciylus likewise afforded Dr. Farre an ojypcrtunity of witnessing the second mode of reproduction common to the Bryozoa, namely, by the development of ciliated gem- mules. These are readily seen in Spring as minute whitish points situated just below the surface of the mass (^Jig, 64, a ). Sometimes Fig, 63. 77«'n tr-ansverse section of Halodaciylus diaplwnus. Tim centre occupied by cellular tissue and water. The circumference formed by cells in close apposi- tion. The brown bodies scattered through the sub- stance. a, a, position of the gemmules, enclosed in the sac ; b, one of the gemmules escaped during the sec- tion into the central tissue. {After Farre.^ they are of a darker colour, and exceedingly numerous, appearing to occupy almost its whole substance. If one of these points be carefully turned out with a needle, it is found 58 POLYPIFERA. to consist of a transparent sac, in which are contained generally from four to six of the gemmules, which, as soon as the sac is torn, escape, and swim about with the greatest ac- tivity, affording a most interesting subject for microscopic investigation. When viewed with a power of 40, linear measure, they are seen to be of an oval or rounded form {fig. 63, b), convex above and Fig. 64. Halodactylus diaphanus, a gemmule seen from above ; the cilia as when slowly acting round the margin in waves. {After Farre.) nearly plane below, and fringed at the margin with a single row of cilia, which appear to vibrate in succession around the whole cir- cumference. Under an amplification of 120 they assume a different aspect {fig. 64), and their minute structure is clearly discerned. Viewed as opaque objects, both the body and ciha have a silvery whiteness, but by transmitted light the former appears of a dark brown, and the cilia of a golden yellow colour. Upon the most convex part of the body, which is not generally in the centre, but leaning to one side, are set from three to five transparent bosses, surrounded by a circle, and other circles are seen extending to the base of the body, which is bounded by a row of promi- nent tubercles. These marginal tubercles are from thirty to forty in number; and from the circumstance of the cilia arising from them, Dr. Farre considers it probable that they are for the purpose of governing their motions, and therefore analogous to the muscular lobes of Hydatina senta and other Rotfern figured by Ehrenberg. No structure, however, could be detected in these, nor in any other part of the body, beyond a mere granular parenchyma. When thus highly magnified, it is seen that what examined with a lower power appeared to be a single cilium is, in fact, a wave of cilia, and that their motion, instead of being in the direction of the circumference of the disc, is at right angles to it. The ciliary phenomena are the most readily observed when the gemmule is nearly at rest, or has become languid ; it then lies either with the convex or the concave side uppermost, and with the cilia, which are of great length, doubled in the middle upon themselves, so that their extremities are brought back nearly to touch the margin of the disc from which they arise. The whole fringe of cilia is then suddenly unfolded, and after waving up and down with a fannmg motion, they are either again folded up towards the under surface of the body, or they commence their peculiar action. As the cilia have the appearance of moving in waves round the disc {fig. 64), each wave may be thus analysed. From a dozen to twenty cilia are concerned in the production of each apparent wave, the highest point of which is formed by a cilium extended to its full length, and the lowest point between every two waves by one folded down com- I)letely upon itself, the intervening space being completed by others in every degree of extension, so as to present sojinething of the outline of a cone. As, however, the persistence of each cilium in any one of these positions is only of the shortest possible duration, and each takes up in regular succession the action of the ad- joining one, so that cilium, which by being completely folded up formed the lowest be- tween any two waves, now in its turn, by its complete extension, forms the highest point of a wave ; and thus, while the ciha are alter- nately bending and unbending themselves each in regular succession after the other, the waves only travel onwards, whilst the cilia never change their position in this direction, having, in fact, no lateral motion. When the waves travel very rapidly, they appear smooth on one side and fringed on the other. The whole of the ciliary motions are so evidently under the control of the animal, as to leave no doubt on this point. The whole fringe of cilia may be instantly set in motion, and as instantaneously stopped, and their action regu- lated to every degree of rapidity. Sometimes one or two only of the waves are seen conti- nuing their action, while the remainder are at rest, or isolated cilia may be observed slowly bending and unbending themselves, or pro- jecting entirely at rest. The body is generally pointed towards one extremity of the oval, and at this part may be observed a bundle of cilia longer than the rest, and moving very rapidly. Their vibrations were in several instances counted very evenly at 230 a minute, continuing in action when all the others were folded up. These Dr. Farre thinks may be respiratory whilst the others are chiefly loco- motive. Dr. Farre thinks there can be little doubt that this explanation of the action of the cilia in the gemmules is applicable like- wise to those of the tentacula of the adult animal, and not only in the Hylodactylm, but throughout the class generally; for he ob- served that the tentacular ciha are infinitely more numerous when at rest than they appear to be when in motion, and also that they vi- brate, not in the direction of the plane of the arms, but at right angles to it, and with the same hook-like form as in the gemmules. In this way the apparent traveUing of the cilia up one side of the arm and down the other, as the eye is seduced to follow the waves which they seem to produce, is at once ex- plained. It would be impossible to account for the POLYPIFERA. 59 variety of motions which the gemmules are capable of executing, were it not obvious how complete is their control over the action of the cilia, which are their sole locomotive organs. They generally swim with the convex part forwards, and with the greatest rapidity. Sometimes they simply rotate upon their axis or they tumble over and over, or, selecting a fixed point, they whirl round it in rapid cir- cles, carrying every loose particle after them. Others creep along the bottom of the watch- glass upon one end with a waddling gait; but generally, after a few hours, all motion ceases, and they are found to have attached themselves to the bottom of the glass. At the expiration of forty-eight hours the rudi- Fig. ments of a cell were observed extending be- yond the margin of the body, but at this stage the animals invariably perished, and Dr. Farre had no opportunity of witnessing their further metamorphosis.* Reproduction by ova. — In the genus Pedicel- Una Van Beneden discovered in most of the individuals he examined, situated immediately above the stomach, some rounded opaque cor- puscles of a lactescent appearance {Jig. 65, which seem to be attached to that viscus ; this he considers to be the ovary, containing ova in various stages of development. In the same situation he perceived an organ that he * Phn. Trans. 1837, p. 410. 65. Pedicellina Belgica. A. Section. B. A group of individuals in various states. The letters refer to each of the pohT)es. a, mouth ; h, oesophagus ; c, stomach ; d, pylorus ; e, intestine ; f, anus ; g, tentacular sheath ; h, ten- tacles; i, oral disc ; k, o\um in the ovary; I, parietes of the pol\TDary; m, stalk; n, superior, and 0, inferior, enlargement ; p, muscles of the stalk; q, intermuscular cellules? 1. An adult individual retracted into its cell, showing the uuiscular fasciculi; r, sphincter; s, retractor; t, oblique ; m, v, animalcules accidentally attached to the stalk ; 2, 3, 4, pol}T)es in the act of expanding ; 6, 6, 7, young individuals; 8, buds in different stages of development ; a, 8, xery rudimentary ; h, 8, shomng the celhde; c, 8, d, 8, a little more ad- vanced ; e, 8, the embryo \asible ; 9, the connecting stalk ; 10, an enlargement giving rise to several buds; 11, tentacle magnified ; 12, a httle group of the natural size. (^After Van Beneden.^ 60 POPLITEAL REGION. looks upon as being the testis, his opinion being founded on the fact that when a mature specimen of the animal is placed between two plates of glass, and gently compressed so as to rupture its parietes and cause the escape of the viscera, spermatozoa are discoverable in the one and ova in the other. The sper- matozoa exhibit considerable vivacity in their movements, have a disc-like body and a cau- dal filament, and are proportionately of large size ; around them may be seen multitudes of free cellules without caudal appendages, which are apparently young spermatozoa. In some individuals the spermatozoa are so numerous that the intestinal canal appears completely enveloped by them, and the whole peri-intestinal cavity seems alive with their movements. In the mature ovary ova are discoverable in ditferent degrees of development, in each of which the vesicles of Wagner and of Purkinje are, according to Professor Van Beneden, dis- tinctly visible. In those ova which approach their complete maturity an external vitelline membrane, or chorion, and a vitellus are per- ceptible, but the two vesicles above men- tioned have disappeared. When arrived at the proper term the ova break from their envelope, or ovisac, and fall into the general cavity of the body, where they move freely about surrounded on all sides by spermatozoa. At length the eggs accumulate in the interior of the body, near the base of the tentacula, and their escape, as witnessed by Van Beneden in Laguncula repens, is at length ac- complished in the following manner. An egg presents itself at an orifice, situated in the vicinity of the anus, through which its external membrane partially protrudes, constituting a sort of hernia (Jig. 61, p). The vitellus gra- dually flows from the still enclosed portion of the egg into that which is external, and when the vitellus has thus entirely passed out, the egg is found sej)arated from the parent animal and falls into the surrounding water. These eggs are entirely destitute of external cilia, and are carried off by any casual current to attach themselves where chance may bring them ; they are also remarkable for the irre- gularity of their shape, some being completely angular, their form seeming to depend upon the pressure they have been subjected to in the interior of their parent. Development hy ova. — In Pedicellina Pro- fessor Van Beneden has witnessed the escape of upwards of twenty eggs from a single indi- vidual. They are of a pyriform figure, and enclosed in a pellucid membrane, by the in- tervention of w^hich they adhere together {Jig. 66. 1), so that in the interior of the body of the parent Bryozoon they have a racemose appearance, and when extended spontaneously they are generally united together in pairs. Between the vitellus and the envelope of the egg there is dways a small (juantity of a trans- parent whitish fluid, which doubtless repre- sents the albumen, while the pellucid external membrane itself is the chorion. The vitellus breaks up into granules, at first of large size, and afterwards by sub- division of smaller and smaller dimensions, giving a tuberculated appearance like that of a raspberry to the mass. This division seems to be accomplished exactly as in the ova of the higher animals, the yolk first separating into two {Jig. 66. 3), then into four {Jig. 66. 2), after which its breaking up proceeds rapidly {Jig. 65. 4). Fig. 66. r 1 . o 1 A series [illustrating the development hy ova of Pe- dicellina. {After Van Beneden.^ The embryo enclosed within the egg soon assumes a rounded form and speedily appears divided by two indentations near its middle {Jig. 66. 5), by which it is separated into an anterior and a posterior moiety, and vibratile cilia become apparent upon the anterior ex- tremity. That portion where the cilia have become apparent insensibly enlarges and assumes the shape of a funnel (Jig. 66. 6), while the long cilia by which it is fringed begin to keep the particles suspended in the water around them in rapid motion. The margins of the funnel gradually extend themselves {Jig. 66. 7), the body exhibits frequent contractions, and at the end of about two hours little tubercles become apparent upon its anterior extremity, which subsequently become developed into the tentacula. Professor Van Beneden thinks that the original cilia disappear when the ten- tacula have become developed and furnished with their proper vibratile apparatus. The formation ot the tentacula at once indicates which are the two extremities of the body and the point by which the embryo will subse- quently attach itself. The embryo when mature is quite at liberty and strikingly resembles some forms of Infu- soria, but after a little while a pedicle is formed, whereby it proceeds to fix itself to some foreign body, and thus permanently assume the aspect of its race {fig. 66. 8). The pedicle seems to be formed by a cell developed below the stomach, which grows directly outwards, and thus completes the organisation of the young Bryozoon. ( T. Rymer Jones.) POPLITEAL REGION, and POPLI- TEAL ARTERY. —The term Popliteal Region is applied to that portion of the POPLITEAL REGION. 61 lower ' extremity which occupies the bend of the knee, and includes also the poste- rior surface of the thigh, as high as the junction of its middle and lower thirds, and the back part of the upper fourth of the leg : — by its muscular boundaries this region is distinctly defined, and is of a diamond shape, but it is by no means so accurately limited when examined with reference to its surface. The external form of the popliteal region differs materially in the flexed and extended position of the leg ; in the latter case, it has somewhat of an oval outhne, the longest dia- meter, which is in the vertical direction, greatly exceeding the transverse : the greatest transverse breadth is at the bend of the knee- joint. The surface presents an elongated rounded projection, which is received above between two narrow ridges diverging from each other as they are traced downwards ; these latter are produced by the stretching of the skin over the tendons of the hamstring muscles, and are rendered still more distinct by a more or less deep groove, w hich sepa- rates them on either side from the general convexity of the region ; inferiorly, the con- vexity of the surface passes off insensibly to the calf of the leg : these characters are more marked in the strong and muscular. When the leg is bent upon the thigh, the roundness of the upper part of the region is lost, and gives place to more or less of a depression or pit between the still projecting ridges produced by the hamstring muscles ; this depression is popularly known as the hollow of the ham. The popliteal region is scooped out into a deep, narrow, diamond-shaped cavity, to which in the following description the term " popli- teal space " will be applied ; it is situated between the diverging hamstring muscles and the converging heads of the gastrocnemius, and is broader above the knee-joint than be- low ; it is filled up by a considerable quantity of fat with areolar tissue, and traversed by the popliteal vessels and nerves ; the semi- tendinosus and semimembranosus muscles on the inner side, and the biceps flexor cruris on the outer, bound this space laterally and above ; the two heads of the gastrocnemius with the plantaris muscle form its lateral boundaries below ; anteriorly it is bounded by the posterior surface of the femur, the knee-joint or rather its posterior ligament, and the popliteus muscle, and is closed in posteriorly or superficially by a strong fascia and the skin : it may be as well to mention, that in dissecting the popliteal space we are looking at it from behind, so that the term superficial relates to its posterior aspect. Before describing the contents of the space, it will be necessary to consider more at length the structures which constitute its boundaries. The skin and subcutaneous areolar tissue present no very remarkable features for exami- nation ; the former is marked at the bend of the joint by a few transverse furrows, which are obUterated when the leg is fully extended ; it is smooth and adherent to the subjacent tissue. This latter differs in no respect from the same structure elsewhere ; it contains a variable amount of fat, and is traversed above by a few filaments from the posterior cuta- neous nerve of the thigh, and below, though not invariably, by the posterior saphena vein. This superficial vessel begins, by small branches, at the outer side of the foot, passes behind the outer malleolus, and crosses ob- liquely to the middle Ime of the leg, then ascends vertically upon the aponeurosis, which it frequently perforates before reaching the popliteal region, passes into the space between the heads of the gastrocnemius to terminate in the popliteal vein ; it occasionally sends upwards a branch upon the fascia lata, which, winding round the inner side of the thigh, joins the saphena major vein. The commu- nicans tibialis nerve courses with this vein, which it closely accompanies at the lower part of the leg, but is separated from it in the popliteal region by being buried between the heads of the gastrocnemius. The posterior saphena vein is liable to become varicose, but less frequently so than the saphena major : this circumstance is of course readily accounted for by the difference of length and size be- tween the two. The fascia lata, descending from the pos- terior surface of the thigh, forms the strong aponeurosis which closes in the pophteal space behind ; stretched across this region, it is connected on either side with the condyles of the femur and the tendons of the extensor muscles of the leg, and continued around the joint ; it is especially fixed to the outer lip of the linea aspera by a septal process of the fascia lata which dips between the vastus ex- ternus and biceps muscles, and on the inner side receives fibres from the tendons of the muscles which pass behind the inner condyle ; it approximates the lateral boundaries of the space, gives to it a greater depth, and protects the vessels and nerves by bearing off from them any undue pressure. By its unyielding and dense structure, aneurismal or other swellings are delayed in their approach to the surface, and for the same reason abscesses are prone to burrow and require an early and free opening. This aponeurosis presents numerous trans- verse fibres, is perforated sometimes by the saphena minor vein, and is adherent by fibrous slips w^ith the subcutaneous areolar tissue ; it is continuous below with the aponeurosis of the leg.' The muscles forming the boundaries of the popliteal space will be considered only so far as they relate to it ; their more detailed descrip- tion will be found in the articles Muscles of THE Leg and Thigh. The semitendinosus muscle, after separating from the biceps, termi- nates in a long, slender tendon, which descends inwards, lying upon the surface of the semi- membranosus ; then crosses the inner head of the gastrocnemius, and placed between^t and the tendon of the semimembranosus, winds round the inner condyle to pass to its insertion. The semimembranosus in descending at first crosses obliquely the popliteal artery, continues membranous and fleshy to the condyle of the 62 POPLITEAL REGION AND ARTERY. femur, and is of sufficient breadth, at this its lower part, to extend beyond either side of the tendon of the former muscle, thus contracting the lateral dimensions of the bottom of this space by encroaching within it. The long head of the biceps, leaving the former muscles, de- scends obliquely to cross the outer origin of the gastrocnemius by its strong tendon, which is subsequently implanted into the head of the fibula ; it receives, as it descends, the thick fleshy mass of its shorter portion, which assists the semimembranosus in narrowing the bottom of the popliteal space, shutting it in also exter- nally and above, by its attachment to the linea aspera as low as the outer condyle. The supe- rior angle of this space is formed at the point of divergence of these hamstring muscles, and the lateral angles are occasioned by their crossing the heads of the gastrocnemius ; this latter muscle is attached to either condyle of the femur by its two heads, the internal being the longer and larger ; they converge to unite in the median line a little below the knee-joint : these origins have each a bursa interposed be- tween them and the condyle ; the little fleshy belly of the plantaris muscle accompanies the outer head and lies beneath it ; by their union the inferior angle of the popliteal region is pro- duced. At the bottom of the space we meet with, first, the posterior, flat, triangular surface of the femur, and, secondly, the back part of the knee-joint strengthened by its posterior liga- ment (the ligament of Winslovv). This struc- ture is derived from the tendon of the semi- membranosus ; it insinuates itself beneath the inner head of the gastrocnemius, and, forming a flat and dense tendinous aponeurosis, extends across the back of the joint to the external con- dyle, adheringto the synovial membrane ; there are several small openings in it, produced by a separation of its fibres, for the passage of vessels to the interior of the articulation : — lastly, the popliteus muscle, which is flat, triangular, and situate behind and below the joint, begins, by a round tendon, from the outer condyle and spreads out by muscular fibres upon the poste- rior surface of the tibia to be inserted into its oblique ridge. On removing the fascia, two large nerves are seen to traverse the popliteal space, and are in- differently called the internal popliteal or tibial, and the external popliteal or peroneal nerves ; they are the terminal branches of the sciatic, which nerve generally bifurcates at the upper angle of this region : the point of division, how- ever, is very variable, sometimes occurring even within the cavity of the pelvis, in which case, as the two nerves emerge, they are usually sepa- rated by a slip of the pyriformis muscle ; com- monly a very trifling dissection will affect their separation some distance up the thigh. The internal popliteal or tibial nerve is the larger of the two, and appears to be the continuation of the sciatic ; it takes a nearly perpendicular course through the popliteal space in the middle line, and will be found at first to lie almost im- mediately beneath the fascia, a small quantity of fat intervening ; it dips more deeply into the space as it descends, passes between the heads of the gastrocnemius and over the popliteus muscle, and, insinuating itself beneath the ten- dinous arch of the soleus, courses down the back of the leg under the nam.e of posterior tibial. Owing to the oblique direction which the popliteal artery follows, this nerve alters its- relation to it at different parts of its course ; until they reach the bend of the knee, the nerve is a little distance to the outer side of the artery, but superficial or posterior, and separated from it by a thick layer of adipose tissue : at the joint, the nerve is still posterior to,but in closer relation with it, and subsequently upon the popliteus muscle crosses the artery to gain its inner side. About the centre of the popliteal space, the tibial nerve sends off* a small branch called the communicans tibialis, which descends superficially between the heads of the gastro- cnemius.and is afterwards concealed in agroove formed by their union ; it perforates, at a va- riable point, the aponeurosis of the leg, and, de- scending towards the outer malleolus, is joined a little above it by the communicans peronei, a branch of the peroneal nerve ; thus reinforced, it is increased in size, and, accompanied by the posterior saphena vein, winds behind the outer ankle to be continued along the outer side of the foot. To return to the internal popliteal nerve, which sends off', while crossing the back of the joint, four or five other branches for distribu- tion to the gastrocnemii and plantaris muscles, and also furnishes some articular twigs ; these are all accompanied by corresponding branches of the popliteal artery, and from ti.eir situation are liable to be compressed by an aneurismal tumour. The external popliteal or peroneal nerve descends along the inner side of the bi- ceps muscle, by which it is guided to the head of the fibula, and winds round the neck of that bone beneath the peroneus longus muscle to divide into its terminal branches ; in the ham it gives off" the small branch called the communicans peronei. This will be seen to de- scend over the outer head of the gastrocnemius muscle and beneath the fascia, and, piercing the aponeurosis of the leg at a very variable distance above the outer angle, joins the com- municans tibialis ; it presents frequent varieties both with regard to its size and the point of junction with the last-named nerve : occasion- ally the union occurs in the popliteal space. To reach the popliteal vessels, a quantity of fat which fills up this space must be dissected out : it is very abundant, and surrounds and supports the popliteal artery. The Popliteal Artery is simply a conti- nuation of the femoral, and is so named immedi- ately after the latter vessel has passed through the elliptical aperture of the adductor muscles ; this opening is bounded above by the united tendons of the adductor longus and adductor magnus muscles ; inferiorly, by the union of the vastus internus tendon with that from the ad- ductor magnus which descends to the inner condyle ; externally, by the tendon of the vastus internus, and internally, by that of the adductor magnus. Passing through this tendinous aper- ture, the artery is at first situated on the inner side of the femur at the junction of its middle POPLITEAL ARTERY. 63 and inferior thirds, and descends obliquely outwards and from before, backwards through the popliteal space, to the lower border of the popliteus muscle, where it terminates, after having gradually diminished somewhat in size, by dividing into the anterior and posterior tibial arteries. When viewed with regard to the vertical axis of the popliteal region, the artery certainly takes an oblique course out- wards ; but in reference to the mesial and perpendicular line of the body, this obliquity is more apparent than real, and depends upon the direction inwards which the shaft of the thigh bone follows ; and this appears evident by the artery passing vertically and midway between the condyles of the femur. Its course from before backwards is very decided until it has attained the superior border of the popli- teus muscle; but as the lower portion of the popliteus is on a plane a little anterior to the upper, and as the artery is applied upon its posterior surface the course will be changed for a direction forwards, so that the artery describes a slight curve, convex backwards, and the concavity corresponding with the back of the knee-joint. When the leg is flexed upon the thigh, the popliteal artery follows the bend of the articulation, and is curved forwards without lateral tortuosity, the curve agreeing with the angle of flexion ; this alternate straightening and bending of the artery during the movements of the leg has been assigned as a reason for its being so frequently the seat of aneurism ; on the other hand, it has been stated that forced extension of the leg, carried even to rupture of the liga- ments of the joint, may be made without in- jury to the artery. The popliteal artery is closely related to its accompanying vein ; as they are entering the space, the vein lies to the outer side of the artery, and superficial or posterior to it, and changes its relation near the joint only to become still more directly posterior : they are enveloped in a common sheath, which is continued from the femoral region (see Femoral Artery), and by which they are intimately connected with each other. The artery is at first deeply seated in the po[)liteal region, and guided into it by the inferior boundary of the elliptical tendinous opening; it then descends obliquely upon the flat triangular surface of the femur to the knee-joint, resting in its course upon a cushion of fat which is interposed between it and the bone, and thicker below than above, so as to well support the artery as it inchnes back- wards from the femur to reach the posterior aspect of the joint. For some distance from its commencement it is concealed beneath the semimembranosus muscle, the thick fleshy belly of which obliquely crosses it behind ; emerging from under cover of this muscle, the artery continues its course to the condyles of the femur, between the biceps on the outer side, and semimembranosus and semitendinosus on the inner ; a considerable quantity of fat sepa- rates it from, posteriorly, the aponeurotic fascia, closing in the space behind, and from the skin. As the internal popliteal or tibial nerve descends vertically in the axis of this region, it must necessarily lie to the outer side of the artery in this part of its course ; and as the nerve is found almost immediately beneath the fascia, it is therefore superficial or posterior to the artery, from which it is sepa- rated by more or less fat. While thus buried in fat, three or four lymphatic glands are closely related to the artery, often indeed sur- rounding it, one to either side, another super- ficial, and a fourth occasionally found between it and the femur. Should any of these glands become enlarged, the impulse such swelling would receive from the artery might lead to its being mistaken for aneurism. We next find the popliteal artery crossing the bend of the knee-joint, and resting upon its posterior ligament ; it descends between the condyles of the femur and the two heads of the gas- trocnemius to the upper border of the popli- teus muscle : the little fleshy belly of the plantaris is also related to its outer side. In this stage the accompanying vein is more directly behind it, and the tibial nerve, coming into closer relation with the artery, from which it is separated by the vein, is also pos- terior or superficial to it, with a tendency to cross to its inner side. At this part of its course the nerve usually sends off", first, the communicans tibialis, and then its branches to the heads of the gastrocnemius, so that the relation which the nerve and its branches have to the artery at this point will readily account for the pain or numbness generally attendant on aneurismal tumours in this region ; so, also, for oedematous swelling of the leg under the same circumstances, we have only to refer to the relative anatomy of the vein and artery for its explanation ; posteriorly, the artery is sepa- rated from the fascia and integument by more or less fat, and is still a considerable distance from the surface; for the tendons of the ham- string muscles, and the condyles of the femur with the heads of the gastrocnemius, so bear off from the artery the skin and fascia as to leave it in a deep and narrow hole, resting upon the posterior ligament of the joint, and con- cealed behind by, first, the vein, and then the tibial nerve. Of course any operation upon the artery while thus situated would be impracti- cable. Lastly, the artery gains the posterior surface of the popliteus muscle, upon which it descends to terminate by dividing into the anterior and posterior tibial vessels ; this divi- sion occurs at the lower border of the muscle, and opposite the interval between the tibia and fibula. The artery is deeply concealed between the heads of the gastrocnemius as they ap- proach each other to unite; the tibial nerve crosses to gain its inner side, and the vein, which often receives the tibio- peroneal vein while upon the popliteus, is still posterior to the artery. Varieties. — The popliteal artery very seldom exhibits any deviation from its usual arrange- ment ; occasionally, its point of division occurs higher in the popliteal space. Professor Har- rison mentions to have seen the artery divide between the condyles of the femur. Instances 64 PORIFERA. have been recorded of a high division of the femoral artery (see Femoral Artery), and where two popliteal arteries existed ; but the artery generally appears particularly free from any variety. Branches of the popliteal artery. — These are very numerous, and of considerable importance in maintaining a collateral circulation when the femoral artery has been obliterated by operation or disease ; they are not always constant, either in number or size. The popliteal artery first sends some irregular branches to the hamstring muscles, the rami musculares superiores ; then five articular arteries, two of which usually arise a little above the joint, and are called ex- ternal and internal superior articular, and two below, the external and internal inferior arti- cular ; the last is anazygos branch. After giving off these articular arteries, the popliteal sends several large branches to the gastrocnemii muscles, the rami musculares inferiores. The superior muscular branches are two or three in number, which are distributed on either side to the hamstring muscles and anastomose with the perforating arteries of the profunda. The superior external articular artery is of some size, and arises from the outer side of the popli- teal at a variable distance above the outer con- dyle of the femur; it descends to wind round the bone under the biceps muscle, which latter it supplies and divides into superficial and deep branches ; the former are distributed to the vas- tus externus muscle, and, by passing through its substance, terminate on the patella ; the lat- ter supply the synovial lining of the articulation, and the lower extremity of the femur itself. These branches anastomose with those of the inferior external articular artery, and with the long branches of the external circumflex from the profunda, which descend in the substance of the vastus externus towards the knee. The superior internal articular artery arises from the inner side of the popliteal above the inner condyle, and also winds round the femur, passing beneath the tendon of the adductor magnus muscle; like the external articular, it divides into superficial and deep branches, the former penetrating the vastus internus to ramify on the patella, and anastomoses with the ex- ternal articular and the anastomotica magna from the femoral ; the deeper branch is distri- buted to the synovial capsule and femur. The azygos branch is derived from the ante- rior aspect of the popliteal while it is in relation with the posterior ligament of the joint ; it di- vides into branches which pass through the liga- ment, and supply the synovial membrane and crucial ligaments of the joint. The inferior ex- ternal articular is given off from the outer side of the popliteal a little below the articulation, and winds round the outer surface of the ex- ternal semilunar cartilage, passing beneath the plantaris and outer head of the gastrocnemius muscles ; it then courses forward above the head of the fibula, and beneath the external lateral ligament to divide into branches, which anastomose with the anterior tibial recurrent and the other articular arteries. The inferior internal articular artery is generally rather a large branch, and descends to the internal lateral ligament, beneath which it passes to gain the front of the tibia; it divides into numerous branches which are distributed to the structures about the inner side of the joint, and which anas- tomose also with the other articular branches. These articular branches of the popliteal are seen, when well injected, to form a beautiful network of vessels around the knee-joint; by anastomosing with the external circumflex and perforating branches of the profunda, with the anastomica of the femoral and the recurrent tibial artery, and also with each other, a very sufficient collateral circulation is usually main- tained in cases where the femoral artery has been obliterated.* The inferior muscular branches are derived from the popliteal artery while passing between the heads of the gastrocnemius ; they are four or five in number, and often of considerable size; accompanied by branches from the tibial nerve, they descend in the substance of the gastrocnemii muscles, and maybe traced some- times to the tendo Achillis ; generally, a small branch from one of them descends with the communicans tibialis nerve. These vessels are sufficiently large as occasionally to require a ligature after amputation of the leg. The course of the popliteal vein has been already noticed in connection with the artery; it is remarkable for the thickness of its fibrous coat, and is formed by the junction of the ante- rior tibial veins with a trunk called the tibio- peroneal : this latter vessel is produced by the confluence of the posterior tibial and peroneal veins. The popliteal vein receives the veins which accompany tlie branches of the popliteal artery, and also, about the centre of this re- gion, the vena saphena minor. Operative relations of the popliteal artery. — Operations upon the artery in this region are now never undertaken, unless, perhaps, in cases of injury with an external wound, the size and direction of which will vary the surgical treat- ment to be adopted ; a ligature may be passed round the artery in the upper part of its course as it emerges from beneath the semimembra- nosus muscle, the outer edge of which will act as a guide to the first incision. After dividing the fascia, the finger, sunk into the space and carried upwards upon the outer surface of the semi-membranosus, will reach the artery ; the vein lies behind it, and a little to the outer side, and will therefore be reached first ; the needle must be insinuated between the artery and vein, and carried round the former from without in- wards. This operation is mentioned merely as being practicable ; in the rest of its course the relations of the artery are such as to prohibit any surgical operation upon it. {William Trew.) PORIFERA {iropos (jyepw, canal-bearing). A word applied by Professor Grant to designate * I have witnessed one instance where mortifica- tion of the leg ensued after the application of a ligature to the femoral artery for the cure of popli- teal aneurism ; amputation was performed above the knee. PORIFERA. 65 a remarkable class of organized beings, dubi- ously admissible into the animal series, usu- ally known by the name of Sponges, which are met with in great abundance in the seas of most climates, either growing in isolated masses from the rocks or f^preading out so as to encrust the surfaces of submarine bodies with a kind of living carpet, the texture of which varies in accordance with the nature of the sponge. By recent naturalists, the term Amorphozoa (afx6p(pos, shapeless; ^<2ov, animal) has been considered a preferable de- signation, and accordingly these names will be applied indiscriminately throughout the present article. According to the most recent authors, the members of the class before us may be ge- nerally described as follows : — " Organized bodies growing in a variety of forms, perma- nently rooted, unmoving and unirritable, fleshy, fibro-reticular or irregularly cellular, elastic and bibulous, composed of a fi|)ro- corneous axis or skeleton, often interwoven with siliceous or calcareous spicula, and con- taining an organic gelatine in the interstices and interior canals ; reproduction by gelati- nous granules generated in the interior, but in no special organ. All are aquatic, and, with a few exceptions, marine." * The families composing the class thus cha- racterised are distinguished by the nature of the skeleton or solid framework upon which their shape depends, in accordance with which Blainville has arranged them as follows : — Alcyoncellum. — Body fixed, soft, sub- gelatinous, solidified by tricuspid spicula, phytoid ; branches not numerous, cylindrical, fistular, terminated by a rounded orifice, with thick walls composed of regular granules ; polygonal, alveoliform, pierced with a pore externally and internally. Spongia. — Body soft, very elastic, multi- form ; more or less irregular, very porous, traversed by tortuous canals, which are nu- merous, opening externally by distinct oscula, and formed by a kind of subcorneous sub- stance w hich anastomoses in every direction ; entirely without spicula. Calcispongia. — Body not very soft,formed in irregular masses, porous, traversed by irre- gular canals, which open externally by oscula, and composed of a subcartilaginous substance, supported by calcareous spicula that are, for the most part, stelliform. Halispongia (xctAis, silex). — Body more or less rigid or friable, in an irregular mass, porous, traversed by tortuous canals termi- nating by oscula scattered over the whole sur- face, and composed of a subcartilaginous sub- stance supported by simple spicula, which are silicious. Spongilla. — Body an irregular mass, more or less rigid and friable, pierced with pores, but without true oscules, composed of a fibro- cartilaginous substance, which is in small * History of British Sponges and Lithophytes, by George Johnston, M.D., Edinburgh, 1842. VOL. IV. quantity compared with the great number of simple silicious spicula which solidify it. Geodia. — A fleshy body, tuberifurm, irre- gular, hollow internally, and formed externally by a sort of crust or envelope pierced with a great number of pores, and contaiiTing a group of oscules or larger pores placed in a little subcircu'ar space. Siphonia. — Body polymorphous, free or fixed, composed of dense fibres, forming two sorts of canals, some larger ami longitudinal, opening by oscula at the bottom as well as on the summit, the others transverse and anastomosing, radiating towards the periphery, and provided with a terminal depression, more or less considerable, in which the oscules are collected in a radiated manner. ScYPHiA. — Body C}lindrical, simple or branched, terminated by a large rounded os- cule, and entirely composed of reticulated tissue. EuDEA. — Body filiform, attenuated sub- pedunculate at one extremity, large, round, and pierced with a great oscule at the other, with pores scarcely visible in irregular lacunas ; whole surface reticulated. Hallirrhoa. — Body turbinated; almost regular, with the circumference circular or lobed, covered with cellules or pores, which are indistinct externally, with a large oscule in the centre of its enlarged part. Tethium. — Body subglobular, irregular, tuberiform, sarcoid but firm, suberous, re- sisting, supported by and mixed up with an immense quantity of aciculi, which are simple, Fig. 67. a, Tethea Cranium of the natural size ; h, section of the same. (^After Johnston.') F 66 PORIFERA. fasciculate, and diverging from the centre to the circumference. Skeleton. — The framework, or fibrous portion, from the arrangement of which the sponge derives its form is composed, as we may gather from the preceding table, of va- rious materials differently disposed in different species, and it is upon the modifications in Fig. 68. A minute portion of the surface of Tethea Cranium magnified; spicula projecting beyond the surface. (^After Johnston.^ the nature and arrangement of the solid por- tions that the general characters of the mass depend. In the true sponges {Spongin), so remarkable for their elasticity and softness, and for their capability of absorbing fluids, properties which render them valuable for many important uses ; the whole substance is composed of horny subcylindrical fibres, which ramify and interlace in every possible direc- tion, anastomosing with each other so as to form innumerable continuous cells and intri- cate canals, the walls of which, in the recent sponge, are crusted over with the gelatinous Fig. 69. Single interspace or open cell, and surrounding finer mesh-work of the skeleton of Euplectella Aspergillum. (^After Owen.) living cortex. The horny threads composing tliis inextricable labyrinth are of unequal thickness, and by some writers have been erroneously described as being throughout tubular ; but this latter is a mistaken view of their structure, dependent upon optical ap- pearances, as has been {)roved by Mr. Bovver- bank * and others, the horny fibres being, in fact, solid and imperforate. In a second group of Sponges, called Halichondria (xaAi?, silex ; x^^^P^^i carti- lage), the solid framework of the body is principally made up of silicious spicula,' im- bedded in the fibre or parenchyma of^ the * Microscopic Journal, vol. i. p. 10. sponge. These spicula, which are composed of pure silex^ are generally united into fasciculi by an enveloping glutinous or condensed cel- lular substance, and by the junction of these fasciculi in various modes fibres are formed, which traverse every part of the body, form- ing the boundaries of canals and orifices, and giving form and support to the whole of the gelatinous or soft cellular substance of the animal.* The spicula, so far as the British species are concerned. Dr. Johnston observes, seem to be always in the shape of simple needle-hke crystals {Jig. 70) ; nor does any Fig. 70. A minute film of the rijid of Tethea Lyncurium com- pressed between plates of glass, and highly magnified to show the needle-like and starred spicula. {After Johnston.) species present us with spicula of two differ- ent forms, though they sometimes vary much in length and gracility ; but he cannot assent to the opinion of Dr. Grant that the form is different in every distinct species, otherwise the task of distinguishing them would be com- paratively easy.-j- A third group of Sponges, designated by Blainvllle, Calccspongia, has the framework which gives them form solidified by the pre- sence of spicula, which are entirely composed of carbonate of lime : in sponges belonging to this group there is, according to Dr. Johnston, no net-work, their basis being a porous mem- brane, rendered compact by the profusion of spicula imbedded in it. The siliceous spicula belonging to the preceding group form mostly needle- like spines ; but there are found along with them, in the genus Tethea, some that might have been the model from which mytho- logicid painters might have drawn the trident they have placed in the hands of Neptune. {fig. 71, d). The calcareous spicula are more variously shaped — either simple and acicular or clavate, or formed with three, or even some- times with four prongs. The two kinds, viz. the calcareous and siliceous, have not hitherto been detected co-existent in any British sponge ; but the spicula of every species are very constant to the same figure, although in point of size they vary exceedingly.;]: " When these spicula are examined through the micro- scope after exposure to a red heat, we dis- tinctly perceive," says Dr. Grant §, " a shut * Grant, Com p. Anat. p. 5. f British Sponges, p. 89. Johnston, loc. cit. Edin. Phil, Journ., xiv. p. 184. PORIFERA. 67 Fig. 71. a, c, d, Spicuia of Tethea Cranium ; d, three forked spicuia; c, fusiform spicuia; a, cuticular spicuia ; 6, spicuia of Tethea Lyncurium. {After Johnston.^ cavity within them, extending from the one point to the other ; and on the inflated part of each spiculum we observe a ragged open- ing, as if a portion had been driven out by the expansion of some contained fluid. In those spicuia which had suffered little change of form by their incandescence, I have never failed to observe the same cavity within ex- tending from one end to the other, and a dis- tinct open rent on their side by which the contained matter has escaped." The exist- ence of this central cavity has likewise been recognised by Mr. Bowerbank, who, more- over, observes, that it is " lined with an ani- mal membrane, which becomes converted into a thin film of carbon when the spicuia are exposed to the action of the blow-pipe." Gelatinous cortex. — " In the recent and living sponge, all its canals and pores are filled with a glairy colourless fluid like the white of an egg, which flows freely out on the removal of the sponge from the water. The quantity af this fluid varies according to the species. In some, it is copious even to nauseousness, but in the compact Halichandriae, there is little of it, and in the Grantiae it appears to be en- tirely wanting." * It " has an unctuous feel, emits a fishy odour when burnt, leaves a thin film of membrane when evaporated, and appears to the naked eye, transparent, colour- less, and homogeneous, like the white of an egg : but when a drop of it is examined on a plate of glass under the microscope, it appears entirely composed of very minute, transparent, spherical or ovate granules like monads with some moisture. These monad-like bodies, nearly all of the same size and form, resemble the pellucid granules or vesicles which Trem- bley has represented as composing the whole texture of the Hydra, or the soft granular matter we observe in the stems of living Ser- * Johnston, loc. cit. tulariae ; and indeed most of the fleshy parts of organized bodies appear to be composed of similar pellucid granular or monad-like bodies in different states of aggregation."* The sen- sible qualities of this glairy material vary in different species of sponge, " the odour of .some being decidedly animal, while others belong to common and well-known vegetables. The Spongia coalita, when newly taken out of the water, smells very strongly of the com- mon mussel, and when burnt it still resembles the same bivalve burnt ; the Spongia com- pressa, on the other hand, smells strongly of the common mushroom ; some, as the Spongia oculata, have scarcely a perceptible odour." Irritability. — According to Audouin f and Milne Edwards, when a living Tethea is allowed to remain for some time perfectly undisturbed in a vessel of sea-water, its oscula may be observed widely expanded, and the currents, hereafter spoken of, passing through them may be readily observed. But if, in this con- dition, the animal is disturbed or removed for an instant from the water, the currents grow much feebler, or cease altogether, and the oscula, contracting slowly and insensibly, be- come at last almost obliterated. In other genera of sponges, however, this contraction has been looked for in vain ; and although the openings of the oscula have been watched with the utmost attention, and measured at intervals with miscroscopic accuracy, not the slightest movement has been perceptible. Circulation of Water. — In the living sponge, as was first remarked by Professor Thomas Bell, and subsequently by other observers, a constant circulation of the surrounding ele- ment, is, by some mysterious agency, kept up throughout its substance, the water being perpetually sucked in, as it were, through all the minute pores, upon the periphery of the mass, and again emitted in continuous streams through the larger orifices (oscula) of the sponge. Fig, 72. Living Papillaris, showing the jets of water emitted from the oscula. (^After Blainville.) Dr. Grant put a small branch of Spongia coalita with some sea water into a watch-glass, in order to examine it with the microscope, and thus describes the phenomena it pre- * Grant, loc. cit. t Hist. Nat. du Litt. de la France, vol. i. p. 78. F 2 68 PORIFERA. rented : — " On moving the watch-^lass, so as to bring one of the apertures on the side of the sponge fully into view, I beheld, for the first time, the s[)lendid spectacle of this living fountain, vomiting forth from a circular cavity an impetuous torrent of liquid matter, and hurling along in rapid succession, opaque masses, which it strewed every where around. The beimty and novelty of such a scene in the animal kingdom, long arrested my atten- tion ; but after twenty-five minutes of constant observation 1 was obliged to withdraw my eye, from fat'gue, without having seen the tor- rent, for one instant, change its direction, or diminish, in the slightest degree, the rapidity of its course; I continued to watch the same orifice, at short intervals, for five hours, some- times observing it for a quarter of an hour at a time, but still the stream rolled on with a constant and equal velocity. About the end of this time, however, I observed the current become perceptibly languid ; the opaque floc- culi of feculent matter, which were thrown out with so much impetuosity at the begin- ning, were now propelled to a shorter dis- tance from the orifice, and fell to the bottom of the fluid within the sphere of vision, and, in one hour more, the current had entirely ceased." Subsequently, two round portions of the Spongia panicea were placed together in a vessel of sea-water, with their orifices opposite to each other, at the distance of two inches ; they ap[)eared to the naked eye like two living batteries, and soon covered each other with feculent matter. Dr. Grant then placed one of them in a shallow vessel, and just covered its surface and highest orifice with water. On strewing some powdered chalk on the surface of the water, the currents were visible at a gi eat distance, and on placing some small pieces of cork or of dry paper over the aper- tures, he could perceive them moving by the force of the currents at the distance of ten feet from the table on which the specimen rested. A portion of soft bread pressed be- tween the fingers into a globular form was not moved away in a mass by the stream, but was gradually worn down by the current beating on its sides, and thus propelled to a distance in small flakes. A globule of mercury of equal diameter with the orifice, let fall upon it from a glass tube, was not removed or shaken, and completely stopped the current. In this condition, on piercing the sponge with a needle, a new current was established through the araficial canal thus formed, which con- tinued even afier removing the obstruction from the original orifice. A globule of mercury of any smallness placed over the orifice of a living sponge, is too heavy to be affected by the s^nall column of water which impels against its smooth round surface, flowing at the rate with which it issues from that orifice, and is useful in enabling us to stop up the currents of certain orifices, in order to direct the stream with greater force through a particular aperture which we wish to examine through the mi- croscope. By adopting this plan with some sponges, which have very few and large orifices on the surface, it is distinctly per- ceptible with the naked eye, that the current never enters by the same apertures through which it issues, and we might thus measure the whole strength of the forces employed to produce the currents in any particular speci- men.* Various hypotheses have been suggested to account for the production of these streams of water which constantly percolate the body of the sponge, but all of them have been rejected in turn as unsatisfactory. Ciliary movement might be supposed to be the cause of this phenomenon, were it not that no observer has been able to detect, even with the most powerful n)icroscopes, the presence of cilia in the interior of the aquiferous canals. At certain seasons, indeed, when the ciliated re- productive gemmules described by Dr. Grant are abundantly disseminated through the living cortex of the sponge, it would seem possible that they might have some influence ; but as the currents appear to be equally strong at all periods, even when these gemmules are not developed, this supposition is untenable. Lastly, the laws of endesmosis have been ap- pealed to as capable of explaining the phe- nomenon in question, yet even here there are difficulties not easily got rid of. In speaking of this propulsion of the sea- water through the Halichondria, in which genus it has been principally observed, the crustaceous species being best adapted for the study of its phenomena. Dr. Johnston re- marks-j-, *■ A single observation is sufficient to convince us that this circulation has no- thing in common w^ith that of higher animals, but it has some analogy surely with that imbibition and influx of water into the body of most radiated and molluscous animals which takes place through the skin and through certain canals, which Delia Chiage has de- scribed and figured as their aquiferous system. The canals in both cases are not vascular tubes with membranous parietes, but rather fur- rows, excavated in the flesh or substance of the body, and leading into wider channels equally unlined. They have in common a direct communication with the circumfluent water, which alone ever flows in them, and the en- trance of this water seems to be, in a great measure, or entirely, independent of the will of the animals ; but the polypes and mollusca only have the power of expelling it when they choose by the contraction and compression of the parts which the canals traverse. There is, however, a wider diflerence in the arrangement of the aqueducts, — in the Radiata and Mol- lusca, the pattern is the same in every in- dividual of each species, but in the Sponges it has no constancy, — so that in no two specimens of the same kind do we ever find the arrangement to be exactly alike. This inconstancy seems to prove that the * Edin. Phil. Journal, vol. xiii. p. 104. t Hist, of British Sponges, p. 89. PORIFERA. 69 direction of the aqueducts through the sponge, and the position of their orifices or oscula on the surface, is very much a matter of chance, and that their formation is the result of a mechanical cause Hable to be diverted from its course by exterior circumstances. If we follow the growth of a sponge, we may feel still more confirmed in this view. The species begins as a spot-like crust of uniform texture, porous throughout, and nearly equally so. In this primitive, homologous condition, there is nevertheless a perfect circulation, — a current which seeks the interior, and another which flows from it, to mix with the circumfluent medium. As the sponge grows in extent and depth, the space for imbibition is enlarged, and the centrifugal water, in its efflux, flowing at first into one and tlien into more currents, these gradually make for themselves channels in the cellular texture, the fibres of which are pushed aside, and prevented, by the continu- ance of the stream, from again encroaching on its course. The channels increase in number with the continued increase of the sponge, and as it cannot but happen that they shall oc- casionally open into and cross each other, we have a wider canal formed by the additional flow of water into it. Such of these canals as reach the surface, soon effect for themselves an opening there; for the current in it pushes against the superficial coat that opposes its efflux, and gradually thins and loosens its texture until this ultimately disappears leaving a fecal orifice or osculum. This is frequently a simple circular hole ; but often, on looking within the outer rim, we notice in the funnel from two to five lesser oscula united together, which are the openings of so many canals that have united there ; and sometimes we find spread within the osculum, or over its mouth, a net work of finer texture than the rest of the sponge, but otherwise of the same nature and composition." *' Such, we believe, to be the manner in which the canals and oscula are formed, and hence we cannot give our assent to the notion that the net-work spread over or within them is intended as a ' wise provision '* against the intrusion of noxious animals, or other foreign bodies within the sponge, which seems indeed to be sufficiently protected at these orifices by the efflux of the currents passing continually from them. Neither can it be supposed that the position and elevation of the oscula have * " Wlien we cut a thin piece of the surface of a living sponge, and look down through one of its pores witli the reflecting microscope, we perceive, immediately beneath the projecting spicula Avhich defend the pore, a very delicate network of gelati- nous threads thi-own over the entrance of the tube. This piece of structure is so fine as to be perfectly invisible to the naked eye ; it consists of five or six threads which pass in fi-om the sides of the tube, to be connected with a central mesh ; so that there are five or six meshes thus formed ; and while this soft apparatus is beautifully defended by the pro- tectmg spicula of the pore, it serves still further to guard the interior of the animal from the smallest particles of sand or the minutest visible animal- cules."— Grant, Edinb. PhU. Journ. any foreseen relation with the situation of the sponge in the water. When, according to Dr. Grant, this production spreads level on a rock with an upright aspect, the oscula are raised into crater-like cones, to enable the sponge to clear itself of the excrementitial matters carried out by the centrifugal streams ; but when it hangs pendent Irom the rock the oscula do not rise beyond the surface, l)ecause the necessity of ejecting excrementitial matters to a distance does not exist. This is to be- stow a foresight and instinct on the sponge which even the followers of Lamarck would hesitate to give it, and which we may safely deny it to be possessed of. The form of the oscula depends entirely on the texture of the species, and on the force of the efliuent cur- rents. If the texture be loose antl fibrous it yields easily, and the oscula are level, or nearly so: if more compact the skin is pushed be- yond the surface into a pa|>illary eminence ; and if too firm and dense to \ 'eld to the pres- sure behind, they fall into a level condirion. They are also liable to be modified in some degree by external forces, for the littoral sponge, which, in a sheltered hollow, or fringed pool, will throw up craters and cones from its surface, may be only perforated with level os- cula, when it is swept over, and rubbed down by the waves at every tide." Reproduction. — The following are Pro- fessor Grant's recorded views u|)on this sub- ject. " Every part of the gelatinous matter (which invests the skeleton of the sponge) is covered with minute granular bodies, which are distinctly seen in every species of sponge by the weakest magnifier of the microscope. These granular bodies are represented in the plates of Donati of a spherical form, adhering to the quadriradial fibres of what he has named the Alcyonium primum Dioscoridis. They are quite invisible to the naked eye ; they escape along with the gelatinous matter, and com- pose the greater part of it ; they are connected with each other by the gelatinous matter, and probably by the same medium, have some connection with the spicula, along which they are placed. No part in the organization of a sponge is more constant and obvious than these granular transparent bodies, linmg the interior of every canal from the pnres to the fecal orifices. Their form is not quite spherical, but somewhat lengthened and ovoidal, and they are always attached by one extremity to the gelatinous matter, while their opposite end is seen to project free into the cavity of the canals. Through the greatest magnifier of the microscope no difference can be detected in their forms in different species of sponge ; they all appear to be enlarged, and round at their free projecting extremity, and, when watched with attention, we distinctly see that they possess some power of spontaneous motion both when in connection with the sides of the canals and when lying isolated at the bottom of the water. The ova of the sponge are quite visible to the naked eye, and are seen dissemi- nated through the whole texture of the sponge in the winter season. They are bodies of a F 3 70 PORIFERA. yellow colour, somewhat translucent, pear- shaped, tapering more or less at their narrow end in different species ; their whole outer surface is covered with delicate projecting cilia, and when viewed through the micro- scope, in connection with the parent, we see that the rapid vibration of these cilia produces a distinct current in the water immediately around them, flowing always from their rounded free end towards their tapering fixed extremity, thus assisting the small granular bodies in producing the currents of the sponge during the period of their attachment to the body. They separate from the canals, and are propelled through the fecal orifices early in spring. None of these ova are seen in the sponge in summer, though we can detect no diiFerence in the velocity of the currents at that period. For some time after they are propelled from the interior of the sponge, they swim about by means of the cilia on their surface, and exhibit all those extraordinary phenomena of spontaneous motion which Cavolini, nearly half a century ago, discovered in the ova of the Gorgonia and Madrepore. They at length fix themselves, Uke the ova alluded to, on a spot favourable to their growth ; they lose entirely their original form, and become a flat transparent circular film through which horny fibres shoot ; they soon spread, and assume a form similar to that of the parent." * Genimules. — Mr. Bowerbank has given the following description of the gemmules of Halichcmdria Johnstonia. " The gemmules of this sponge are dispersed in great abundance throughout every part of its substance ; they are of an oval form, the longest diameter being 2T-7th, and the shortest, the ^^^th of an inch. They vary considerably in size, but the above are their average dimensions. When seen by direct light, with a power of 100 linear, they appear of the same colour as the surrounding fleshy matter ; but when viewed as transparent objects they assume an iron or slate-gray colour, having their surfaces closely studded with minute papillEB, which are produced by the projection of the points of numerous very small spicula, which are imbedded in the crust or shell of the gemmule, and are dis- posed in lines radiating from, the centre to the circumference of the body." The form of these minute spicula is ex- ceedingly various ; but the best developed ones appear conical, having their bases towards the centre of the gemmule, and their apices slightly elevating the parts of the outer in- tegument immediately above them. The mode of disposition of these spicula is best observed, w hen a small portion of the sponge has either been treated with boiling nitric acid, or by incineration in the flame of a lamp. The dissolution of the gemmules is not effected by either of these agents, and, to view them with the greatest effect, they should be gently * Edin. Phil. J ourn. ; and Edia. New Phil. Journ. vol. ii. p. 128, &c. triturated with a little water between two pieces of glass, until some of them be broken into small pieces. In these fragments, the spicula may be seen in situ, cemented together apparently by siliceous matter, which appears to abound in the outer integument of the gemmule. Upon measuring some of these minute spicula in situ, Mr. Bowerbank found the average length to be 3-5V0 inch, or about equivalent to the diameter of a disc of human blood, and their average thickness the 2 gi^o inch, so that they are of exceed- ing minuteness as compared wdth those found in other parts of the same sponge. The pro[)agation of Tethea is by means of sporules or gemmules generated within the fleshy substance. The sporules, ac- cording to Dr. Johnston, resemble the parent Fig. 73. a, Oviform bodies found immersed in the paren- chyma of Tethea Cranium magnified; b, one of these bodies viewed through the microscope after compression between two plates of glass. {After Johnston.^ sponge in miniature ; but they have no dis- tinct rind or nucleus, being composed of simple spicula woven together by the albu- minous matter ; and there seems no way of escape for them, except by the dissolution of the body of the parent sponge, which most probably is an annual production. " The natu- ralist*, who believes that sponges have an affinity with the fungi, will see, in these par- ticulars, a correspondency which may strength- en his belief. The Tethea, he may say, is the sea's copy of the earth-born Sclerodern)a, and he may remind us that, like the sporules of sponges, the sporules of fungi are equally locomotive. The Chaos fiingorum of Linnaeus is thus described : — " Habitat uti semen Ly- coperd', Agarici, Boleti, Mucores, reliquorum- que fungorum, in sua matre usque dum disper- gatur et in aqua exclusum vivit et moritur, demum figitur, et in fungos excrescit. Zoophy- torum metaphorphosis e Vegetabiliin Animale fungorum, itaque contrario ex Animali in Vege- tabde." — Svst. p. 1326. The admissibility of sponges into the animal series is, indeed, extremely problematical, and wc doubt not that among naturalists of the present day the balance of opinion would be unfavourable towards retaining them in the rank which they at present occupy in zoolo- gical classification. {T. Rj/mer Jones.) * Johnston, p. 82. PRODUCTS, ADVENTITIOUS. 71 PRODUCTS, ADVENTITIOUS.— The difficulty of defining the term Adventitious Product with precision has so frequently been acknowledged, that we feel extremely diffident in offering anew attempt to the consideration of morbid anatomists ; the more so as the re- cent disclosures of the microscope would pro- bably strike the generality of persons as having, almost of necessity, simplified the task, while they have in realiry rather in- creased its perplexity. Fully conscious, then, of the debatableness of the ground we tread on, we would apply the term Adventitious Product to any substance whichy either pro- duced hy or developed in connection with the animal frame, neither forms a natural consti- tuent element, nor a natural secretive product, of the structures amid which it is evolved. The qualification, " either produced by or deve- loped in connection with the animal frame " is required to ensure the exclusion of Foreign Bodies ; and the latter member of that quali- fication, " developed in connection with the animal frame," as plainly necessary to ensure the inclusion of Parasites, which (whether they be the proceeds of equivocal generation or evolved from germs introduced from with- out) are certainly not produced by the textures containing them. Understood thus, (and the signification seems the widest that can, in a practical point of view, be given to the term,) the character of adventitiousness is conceived to arise in three different ways: — a substance may, in truth, be adventitious, because its nature is different from that of any of the natural tex- tures and secreted materials ; or because the form it has assumed differs from that under which it naturally occurs ; or because the situa- tion it occupies is one to which such substance is in the natural order of things wholly foreign. Thus tuberculous matter is adventitious, be- cause it differs in nature from all the elementary structures and secretions ; a calculus com- posed of lithate of ammonia is adventitious, because the form, assumed by the salt compos- ing it, differs from that it wears as a constituent of healthy urine ; and an ossification of the pleura is adventitious, because the ossiform structure forming it occupies a locality in which, in the healthy state, bone is unknown. The amount of adventitious quality in pro- ducts of these three kinds differs : it is greatest and most clearly defined, where dependent on the nature of the constituent materiid. Thus, in the first place, concerning the adventitious- ness of cancer or pus, no doubt can ever arise ; their physical and chemical characters and their essential nature are decisive of the point. In the second place, when a product becomes ad- ventitious simply from the peculiarity of its localization^ the question is often less clear ; nor indeed can it in the existing state of know- ledge be invariably settled. Muscular fibres have, for instance, been met with in the walls of the ureter ; albumen is excreted in great quantity with the urine in certain states of dis- ease: but whether such muscular fibres are to be considered evidences of hypertrophy or ac- tual new products, and whether such albumen must be viewed as a totally new material of renal secretion, or as a natural element of urine in excess, depends upon the mode of decision of the preliminary questions, whether rudimen- tary muscular fibres do or do not naturally exist in the situation referred to, and whether albu- men do or do not, in excessively small propor- tion,form a natural constituent of human urine. And this is not the only aspect under which it becomes practically difficult to distinguish hy- pertrophous from adventitious products. The two states are in some conditions of disease distinctly and intimately associated. Thus, in eburnation of the heads of bones, the proper osseous tissue undergoes hypertrophy only, while the adjacent articular cartilage becomes infiltrated with adventitious bone. Again, the fat, which forms in abundance in the liver in the so-called " fatty degeneration" of that organ, is at first merely an excess of that naturally existing in the hepatic cells, and can there- fore only be regarded as a product of unhealthy supersecretion : but with the advance of the morbid change, the inter-cell texture of the organ becomes infiltrated with fat ; and this fat is an adventitious product by reason of the lo- cality it occupies. Nature here, as elsewhere, transgresses the artificial limits established for the facilities of study. In the third place, it is clear that newness of form implies the quality of adventitiousness in an infericjr degree only -— that a material naturally existing dissolved in a secreted fluid, for example, does not, when from physical or chemical causes it accumulates in solid masses, possess the quality in question to the same amount as another which is never, under any shape nor even in the minutest pro- portion, a natural existence. The great number and variety of the objects to which the term Adventitious Product, de- fined in the manner we have just proposed, will apply (from a microscopical crystal, for instance, to the highest species of intrinsically vegetative Growths) render it necessary, in limine, to introduce some order into the sub- ject. We shall consequently set out by tracing those lines of distinction which separate from each other the various objects united together by the common property of Adventitiousness. It would, no doubt, be desirable and most strictly logical to employ some one uniform principle in establishing the various divisions and subdivisions of this, as of all other groups of natural objects, which require classification. But in the present state of knowledge, at least, systematic accuracy of this kind is unattainable. Neither the anatomy of texture or of form, the physical or chemical nature or properties of ultimate elements, the mode of formation, the physiological properties, nor the pathological influences of morbid products, will, taken singly, supply a feasible instrument of classifica- tion. All must by turns be made to contribute their share in the work. And as all previous modes of arrangement have been found to bear the impress of contemporary physiolo- gical doctrines, so will the existing impulse towards micrological study be traced in ours. F 4 72 PRODUCTS, ADVENTITIOUS. But we have not pushed the use of micro- scopical characters to extremes, persuaded as we are that more has been done to lower than to raise micrology in general estimation by the attempt to make it (in its present unformed state) the essential and sole groundwork of distinction of organized products. Adventitious products present themselves in the solid, the liquid, and the gaseous states ; and this difference of molecular condition co- incides with so many pathological distinctions, that (although some objections may on " tran- scendental " grounds be raised to the pro- cedure,) we shall found upon it a division of the whole into three corresponding groups. A complete description of the Morbid Anatomy of the more complex of the species composing these groups should, we conceive,* comprise that of their material or physico-chemical characters ; of their origin, progress, and de- cay ; of their intrinsic morbid changes, (for their lives, as the lives of the organism they inhabit, are liable to variations of health and disease, — they are microcosms within a ma- crocosm ;) of the textural alterations they produce in contiguous parts ; and of the modifications their existence entails on the solids and fluids of the economy at large. It is clear, however, that a plan so extensive as this could not be ventured on in the present work ; but, as far as is reasonable, we shall pursue it. GROUP I, SOLID ADVENTITIOUS PRODUCTS. The group. Solid Adventitious Products, resolves itself naturally into two great classes Class I.— Non-Plastic Products or PRECIPITATES. Scb-Class I. ( Saline.) Produced by pre- cipitation from secreted fluids. Sub-Class II. {Anintalized.) Produced by exudation from the vessels. § I. Particles, § n. Masses. Calculi. . Concretions. I. Protein-Compounds. |_§ III. Sugar. (certain forms of the). II. Fat. Class II. — Plastic Products or FORMATIONS. SrB Class I. Products possessed of a dependent ex- istence and derived from a Blastema. Blastemal Forrnaiio7is. Sub-Class II. Products possrssed of independent ex- istence and derived from a Germ. Germ- For maUons or Parasites. Order I. Derived from a blastema which generates cells defi- cient in vegetative faculty ana in per- manency. Deposits. Order II. Derived from a blastema winch generates cells pos- / sessed of vegetative faculty, but defi- cient m permanency. Growths. § I- § 11. § III. § IV. 5 V. Typhous Deposit. Tuberculous ,, Purulent Melanic ,, Diptheritic ,, Order III. Derived from a blastema which generates cells defi- cient in vegetative faculty, but pos- sessed of per- manency. , Pstudo- Tissues. Order I. Animal. Order IT. Vegetable. Sub-Order I. Deficient in the power of destroying by infiltration the natural tissues amid which they are evolved. Non- Infiltrating Growths. Sub- Order II. Possessed of the above power. Infiltrating Growths. Sub-Order I. Sui generis. Sub-Order II. Simulating the natural tissues of the adult. rEntozoi. \ Epizoa. r Entophyta. X Kpiphyta. Of Protein- basis. Of Fat-basis. Of Gelatin-basis Of undetermined basis. Of Protein-basis. Induration-matter. Extra- Vascular. Simple- Vascular. rHaematoma. 1 Sarcoma. <{ Cystoma. Arigeiectoma. ^Melanoma ? ? r Lipoma. ■J Steatoma. L Cholesteatoma, r Fibroma. -J Enchondroma. C Osteoma. ^ CoUoma. Carcinoma. r Epithelium. < Nail ; Hair. C Cartilage. r Cellular ; Serous. J Fibrous ; Elastic, i Osseous. C Nervous. Bloodvessel ; Erectile tissue. Lymph.vessel.. Fibro and Spon-gy Cartilage. Compound- Vascular hate of magnesia is, according to Brugnatelli, of common occurrence, either mixed with triple phosphate, or forming alter- nate layers with it. 14. Chloride of sodium never forms the sub- stance of calculi, and the conditions under which this salt crystallizes in the urine are not well ascertained : partial evaporation of the fluid must first take place. The crystals are octahedral, and have their planes indented like steps of stairs. The nature of the so-called fibrinous calcu- lus (originally described by Dr. Marcet) has been made matter of question by Berzelius. It appears that the material supposed to be fibrin by that analyst was soluble, though not readily so, in nitric acid, — a character not be- longing to either fibrin or albumen. This, with other of its properties as detailed by Marcet, leads Berzelius to regard the matter as inspis- sated vesical mucus. The Museum of University College contains a " fibrinous calculus " taken from the bladder of a cow {fig. 85). It is of irregular elon- gated shape, measuring two and a half by one and a half inches ; very light ; elastic ; of * Med. Chirurg. Trans, vol. ix. p. 14. t ]Med. and Phys. Jomii. vol. Ivii. j Schmidt's Jahrbuch, B. v. S. 379. VOL. IV. brownish grey colour internally, whitish exter- nally, and coated with a white earthy crust. Fig. 85. Section of fibrinous calculus. A new substance has recently been added to the hst of constituents of urinary calculi by Heller*, under the title of urostealiih. This substance is said to form a soap with alkalies, and to have been discharged in small masses varying in size from that of a hemp seed to that of a small nut. Each particular division of the urinary pas- sages is the seat occasionally of calculous for- mations, and the characters of these are in each site more or less peculiar. Into the description of these characters we cannot here enter seri- atim ; of the varieties thus depending upon the seat of the product — namely, renal, ureteral, vesical, prostatic, urethral, and jirceputial , — the most important, the vesical, may be considered to have been specially kept in view in the pre- ceding pages. As respects renal calculi we must content ourselves with illustrating by a figure {fig. 86) the curious branched form Fig. 86. they sometimes assume, as they gradually mould themselves to the interior of the pelvis and infundibula. Renal calculi sometimes attain great bulk. Among numerous examples of the fact we may refer to a case seen by Wilsonf, in which the kidney, perfectly atrophous, and replaced by a raultilocular membranous sac (the dilated pelvis and infundibula) contained an oxalate of lime calculus weighing seven ounces and a half. Renal calculi derive much of their prac- tical interest from their tendency to produce such atrophy of the kidney, with pyelitis (U. C. Mus.) or, more rarely, hydronephrosis. * In seinem Archiv, Bd. ii. t Lectures, p. 122. G 82 PRODUCTS, ADVENTITIOUS. Calculi of the frostate gland are (some- times at least) essentially diflerent in nature from urinary calculi, and belong to the class produced by morbid secretions from mucous surfaces. Sometimes single, they are more generally numerous ; in the latter case, though occasionally found of much greater bulk, they rarely exceed a pea or small nut in size. One variety of prostatal calculus is, according to Dr. Prout, found in the natural cavities of the gland, before this becomes much disorganized ; the calculous masses referable to this variety are of more or less rounded shape and yel- lowish-brown colour. Another variety seems to be generally found in an enlarged cavity or abscess of the prostate gland, and sometimes has a highly polished porcellanous appearance. But that this distinction is rather an artificial than a natural one appears from the similarity of composition of both varieties. As first shown by Wollaston, these calculi consist mainly of phosphate of lime and animal matter with carbonate of lime in variable proportions. PrcBpntial calculi and those found in urinary fistulcB belong, in the great majority of cases, \o the class of saline masses generated through irritation of mucous (or pseudo-mucous) sur- faces, and accordingly consist whoil}' of earthy phosphates. There is no reason, however, that a particle of gravel, or a minute calculus of various chemical constitutions, might not make its way into these situations, and become the nucleus of further deposit : and in point of fact Romer found uric acid, phosphate of lime, and animal matter in some calculi removed from underneath the prepuce of a child affect- ed with natural phymosis. (6). Lachrijmal calculi. — Calculous forma- tions in the lachrymal organs, positively speak- ing rare, are much less commonly met with in the gland and its excretory ducts than in the folds of the conjunctiva, in connection with the caruncula or in the lachrymal canals and nasal duct. They maybe known by the generic name clacryoliih^ (from daicpvov, a tear, and XiOog, a stone,) first proposed by Walther. An example of the actual formation of such calculous masses in the excretory ducts of the gland occurred in the case of a female, aged 19, who came under the notice of Mr. R. H.Meade, (Med. Gazette, 1835.) Twenty-three calculi, of small size, (the largest about a line in dia- meter,) rough, very hard, and of dirty white colour, were discharged from the ducts in the course of four or five days. They consisted principally of phosphate of lime, with a small quantity of carbonate of the same base and traces of animal matter. Von Walther de- scribes a curious case, in which calcareous matter continued to be formed in the folds of the conjunctiva during a space of about ten weeks. The first mass formed was of angular shape, about the size of a pea, and easily ca- pable of being rubbed down into a greasy powder. It reappeared in three days ; and sub- sequently a similar matter formed in the other eye. The deposition ceased under the use of potash internally, but returned three years after; carbonate of lime chiefly, with phosphate of lime and animal matter, were its constituents. Numerous examples are on record of such concretions occurring in the follicles of the caruncida. Sandifort, Blegny, Schmucker, Mr. Travers, and others have seen calcareous mat- ter in the lachrymal canals. Krimer* has de- scribed a calculus of the size of a small pea, of ash-grey colour, polished, of calcareous ap- pearance, removed from the nasal duct of a woman, who for nine months had laboured under disease of the lachrymal passages. There is a species of calculus, essentially of fatty nature, commonly known as " deer's tears," which forms in the fossa just below the anterior canthus of the adult red deer (cervus elephas). It yields on analysis resin with ethereal oil, fatty oil, wax, cellular substance, colouring matter, chloride of sodium, and phos- phate of lime. Some of these ingredients are supposed to be derived from hair, which is usually entangled with it. It is said to pos- sess the medicinal virtues of the foetid antispas- modics.f (c) . JSJ'asal calculi. — Calculous masses are not extremely uncommon in the nares. Some of them are indubitably formed in the lachrymal passages, whence they glide into the nostrils ; such was, in all probability, the case with the little girl spoken of by Bartholinus, who forced small calculi from her nose. In other instances they manifestly originate in the nos- trils themselves; this is especially certain when the nucleus of the mass consists of a foreign body. Thus Horn found a calculus in the nares, the nucleus of which was a cherry-stone. Grandoni removed from the left nostril of a woman, aged 32, a calculus formed of frag- ments of unequal sizes, weighing 76 grains, of a specific gravity of 1.4, without smell, and chemically constituted as follows : — Phosphate oflbne 55.0 Carbonate of ditto 18.0 Carbonate of magnesia 7.0 Organic matter with traces of iron 20.0 100.0 In the largest of the fragments a grass seed was discovered, J (d) Frontal sinus, calculi of — Several calculi of small size, consisting of phosphate of lime, carbonates of lime and magnesia, oxide of iron and soda in small quantity, and animal matter, were discharged from the frontal si}ius of a woman, whose case will be found in a foreign journal. $ ((°.) Mouth, calculi of — The interior of the mouth may become the seat of calculous form- ation. Schenk, Echold, and Bartholinus re- late cases of its occurrence in connection with the mucous membrane of the palate ; Kruger describes a mass of ashen colour, hard, round, * Grtefe and Walther's Jom-ual, Bd. x, S. 597. 1827. t Loweudardt, Brit, and For. !JIed. Rev. vol. xi. p. 233. X Brit, and For. Med. Eev. vol. xi. p. 238. § Gaz. Med. de Paris, t. 1. No. 2. PRODUCTS, ADVENTITIOUS. 83 and very light, thrown off from an ulcer in the palate. Otto * knew a person in whom, during an atonic attack of gout, the whole mouth, throat, and gullet were largely covered with a whitish mucus [diphtheritic deposit ?], which contained a large quantity of phosphate of lime. (/.) Salivary calculi. — The calculous accu- mulations met with not very unfrequently in connection with the salivary glands, are com- monly regarded as depositions from the sa- liva, and may be generically termed ptyaliths {irrvaXov, saliva, and XlOoq, a stone). But they are at the least depositions from saliva of morbid composition, for while they are essen- tially formed of phosphate of lime f , this salt scarcely exists in the healthy fluid, and indeed is not enumerated among its ingredients at all by either Berzelius, Graham, or Wright. It be- comes, therefore, extremely probable that the excess of phosphate is generated through the influence of irritation of mucous membrane. Salivary calculi are of much more common occurrence in some of the lower animals (e. g, the horse, ass, and dog) than in the human subject. The parotid gland is less frequently the seat of these products than the submaxillary and especially than the sublingual gland. Polker extracted an encysted stalactiform calculus, 15 lines long, 9 broad, and weighing 120 grains, from the parotid, composed of phosphate of lime and animal matter. Breschet describes white calculi of scaly fracture, some of them crystallized in regular tetrahedra, and having a nucleus composed of a grain of oats, which were discovered in the maxillary glands of an elephant : here, in addition to phosphate of lime and animal matter, there was carbonate of lime. The affection called ranula is produced by obstruction of the ducts of the sublingual gland with calculous matter, which may form a single large mass, or be united into numerous minute ones. Chronic inflammation and ab- scess are the frequent results of such accu- mulations. Of similar origin is the calculous matter which gathers round the teeth, commonly called tartar or odontoliths {oZuv, a tooth, and XiQoc, a stone). Two kinds of tartar have been distinguished by Duval : a, tartar of deep grey or even blackish colour, hard and com- pact, smooth on the surface, breaking almost like glass, and forming first on the root of the tooth, whence it spreads to the enamel ; 6, tar- tar of yellowish colour, less compact, friable, less smooth on the surface, forming on the enamel near the gums, whence it spreads to the crown in the majority of cases, but sometimes insinuates itself under the gums. Tartar appears first as a thin layer of slimy matter, which hardens ; another layer is then deposited, hardens in its turn, and so on. It accumulates enormously in some instances, exceeds the tooth (to which it is often most firmly united) * Patholog. Anat. by South, p. 103. t Poggiale (Journ. de Pharmacie, p. 337, 1839) found so much as 94 per 100 of this salt. X Bull, de la Faculte de Med. 1815, No. 7. in size, and sometimes detrudes this from its socket. Berzehus found it composed of Earthy phosphates 79.0 Undecomposed mucus 12.5 Peculiar sab vary matter (Ptyalin) 1.0 Animal matter soluble in hydro- chloric acid 7.5 100.0 Buhlmann * has recently drawn attention to certain microscopical corpuscles, most fre- quently met with on teeth surrounded with tartar, yet not altogether absent from the cleanest. Originally described by Leeuvven- hoeck, these bodies are of filiform shape, and found in three conditions : a, yellowish fibres usually collected into tufts; b, the same fibres broken and scattered among the epithelium and mucus ; c, tufts of fibres mixed up with gra- nular matter. They measure about O.OOOOGth of a Paris inch in breadth ; from J-th to i a line in length : they are smooth, arched, or' wavy, somewhat elastic and transparent and of yel- lowish white colour. The strongest nitric, sul- phuric, and hydrochloric acids and caustic alkalies produce no change but that of render- ing them a little more transparent : they are unaltered by heat. They are chiefly abundant at the junction of the tooth and'gum. In- fusoria (genera Vibrio and Monas) are also found in this substance. (g.) The tonsils are not unfrequently the seat of phosphatic deposit. A calculus formed in one of the tonsils, of greyish white colour, containing an oval nucleus, was found by Wurzer to consist of phosphate of lime 63.8, carbonate of lime 16.7, animal matter 13.3, ptyahn with chlorides of sodium and potassium 7.1, iron and traces of manganese 0.1. f (Ji.) The pharynx and oesophagus have both been, though in extremely rare instances, the seat of calculous incrustations. Riviere and Bartholinus relate such cases. (i.) Gastro'intestinal calculi. — The calculi discovered in theintestinal canal agree, as regards such saline materials as enter into their compo- sition, in being essentially formed of earthy phosphates, especially that of lime. They may, however, be wholly free from saline matter. Intestinal calculi are generally few in num- ber, unless when of biliary origin : as many as thirty, however, were found in the stomach by Bilguer. Their size varies remarkably, from that of a nut to a mass larger than the clenched hand : their weight varies proportionally, — tliey have been known to weigh a pound and a half, two, and even four pounds. Their specific gravity is low, varying from 1000 to 1400. Their shape is irregularly rounded, the irregu- larity being greatest in the largest masses, and, like biliary calculi, they affect their own forms mutually by lateral pressure. They occur in all parts of the intestinal tract, but are most * Miiller's Archiv., H, iv. S. 442, 1840. t See also SchUtz, Caspar's Wochenscrift, No. 45, 1838. G 2 84 PRODUCTS, ADVENTITIOUS. common in the cceciim, large intestines, and stomach, and in rare instances have been dis- charged by the mouth. There is a very obvious distinction between intestinal calculi, seized by ahuost all writers on the subject, in regard of their origin : (1.) some originute elsewhere, and make their way into the alimentary canal ; (2.) others are the result of the deposition within the intestines of certain materials around some substance acting as a nucleus, itself either introduced from without or from some other part of the system; (3.) others are wholly formed in the alimen- tary canal. (I.) a. Biliary calculi, to be presently de- scribed, form the great majority of those be- longing to the first class. They present pre- cisely the same cliaracters as while still in con- nection with the biliary system, h. Calculi sometimes pass into the intestine from the urinary passages. Dr. Marcet found a calculus, mainly composed of a mixture of phosphate of lime and tri])le phosphate, in the rectum of an infant with imperforate anus. A communica- tion existed between the bladder and rectum. (2.) Calculi belonging to the second class vary much in respect of their nucleus ; the matter found in the intestine, constituting the cortex of the calciijus, is generally composed of phosphates, applied in layers or not, and mixed or not with additions of the vegetable or other substance which served originally as the nu- cleus ; the mass is solid and coaipact, or softer and more porous, and mixed with the mucous secretion of the bowel. The division into layers is sometimes very indistinctly marked ; gene- rally a slight difference of colour exists in the different strata. Yellowish brown is the most common hue. The nucleus in this class of calculi may be animal, vegetable, or inorganic. {(t.) Anhnal. — Under the name of egagro- piles, or hair-halls^ have been described masses of not uncommon occurrence in the intestines of the lower animals (especially of calves), composed of hairs in their central part, in their outer parts of concrete animal and saline matter. The hairs forming the nucleus are swallowed by the animals when licking them- selves. Laugier* has very carefully described a felty'looking mass of some size found in the human rectum, the cortex of which consisted of fcEces, hydrochlorate of ammonia and lime, phosphate of lime, silica, and oxide of iron ; the nucleiis, prismatic in shape and covered immediately with a brown crust, consisted in its central part of gelatin, in its more external of blood. Probably, as has been suggested, the mass originated, in consequence of a vessel being wounded by a [)iece of bone, — blood being effused round this, and saline matters subsequently accumulated round both. (b.) Vegetable. — Nuclei of vegetable matter are more common. In graminivorous animals intestinal calcuh of this kind sometimes acquire vast size. In a horse (aged 17 years) a mass ♦ Mem. de I'Acad. Roy. de Med. t. i. was found having a nucleus of oat-grains, and so huge as to measure 28 inches round, and weigh 19 pounds (Breschet). Laugier and Lassaigne, in a similar mass, collected round bits of straw, found the cortex composed of earthy phosphates. In the duodenum of the human subject Andral discovered a calculus of the size of a small egg, consisting of earth} - looking matter externally, and having a plum- stone for its nucleus. But the most interesting calculus of this species is endemic in Scotland, and for its full history we are chiefly indebted to the investi- gations of WoUaston and Dr. Monro Tertius.* The vegetable substance acting as the nuclear basis of the mass (which looks like felt or coarse sand) is the husk of the oat-seed in fragments, along with the minute fibrils, form- ing a velvety mass at one end of the seed un- derneath the husk. The abundant use of oat- meal in North Britain, as an article of food, explains the frequent occurrence of these calculi among the population ; they are said by Dr. Maclaganf to be growing less common, in consequence of the greater care now be- stowed in the north in separating the husky matters in preparing grain for the market. The inorganic constituent associated with the vegetable fibrous matter is mainly phosphate of lime (20 per cent, in two specimens ana- lyzed by Dr. Maclagan), associated with silica, evidently derived from the oat (6 and 4 per cent.). (c.) Inorganic. Certain medicines, magne- sia (Monro) and chalk especially, have occa- sionally collected into calculous masses in the large intestine of persons in the habit of swal- lowing large doses of either for a considerable time : the saline matter being hardened into a solid ball with mucus and faecal matter. Croc- kelt I relates the case of a child who swallowed a pin, and at the age of 18 voided per anuni a calculus of spheroidal shape and earthy com- position. The head and half the stem of the pin were enclosed in the mass. A piece of wood accidentally forced into the rectum has been known to form the nucleus for phos- phatic deposition. 5^ Females who chew and swallow the ends of threads used in sewing, or indulge in the singular habit of eating their curling-papers (hysterical pica), occasionally become the subjects of intestinal calculi. (3.) Calculi formed wholly in the digestive passages are comparatively rare. They may consist of faeces and inspissated secretions wholly (under which circumstances the name, calculus, is not in strictness applicable to them), or these may serve as a nucleus for the deposition of the ordinary phosphatic salts. White discovered, near the ilio-coecal valve of a tuberculous subject, two masses (one weighing two, the other one and a-half pounds) com- * Morbid Anatomy of the Human Gullet, &c. 1811. t Lond. and Ediub. Month, Journ. of Med. Sci- ence. Sept. 1841. North American Journal, 1827. Dalilankamp, Archives Gen. de Me'd. t. xxiii. PRODUCTS, ADVENTITIOUS. Acid fatty matter J If 1 composed of [peculiar acid J posed of a nucleus of indurated faeces, and a cortex of saline matter arranged in layers. Oleaginous matters sometimes accumulate in the intestine in the form and of the consistence almost of calculi. A mass of this kind, voided by a young tuberculous female, and examined by M. Lassaigne, was found to consist of f Stearin ! 74 liar acid Substance analogous to fibrin 21 Phosphate of lime. 4 Chloride of sodium , 1 100 These oleaginous formations will be presently further considered. The oriental bezoard, a resinous intestinal calculus, chiefly met with in certain species of goats and deer, appears (like ambergris in the whale) to be the result of morbid secretion from the bowels of the animal, and not to be composed (as was imagined by Vauquelin) of materials derived from its food. A very doubt- ful case of calculus occurring in the hiiman intestine, with close resemblance to ambergris in its characters, has been published by Dr. Kennedy.* We have lately examined some masses composed solely of fibrin, (Univ. Coll. Mus. presented by Dr. Rayner,) passed from the rectum after prolonged sufferings, simulating those of cancerous disease. (Jc.) Biliary. (Gall stones, Choleliths). — Biliary calculi are found in every part of the system where the bile circulates, and even make their way occasionally into localities in which that fluid is not naturally found. Most com- mon in the gall-bladder, they are frequent in the larger ducts ; far less rare than has been affirmed by some writers in the radicles of the hepatic duct, not uncommonly encountered in their transit through the different parts ofthe intestine (where \t is possible they may be sometimes actually formed), they are very rarely seen in the stomach. Biliary calculi vary in number from one to several hundreds and even thousands : 3,646 are said to have been shown by Fuschiusfrom the gall-bladder of a certain gladiarius f ; and Dr. Parry :j: gives a case in which 2,654 were found in the same part. It is not uncommon to find one only, or two, three, or four; but observ^ations are wanting as to the relative fre- quency of small and large collections. Their size varies as their numbers. When single or few in number, they are comparatively large, have been known to reach the bulk of a hen's egg but rarely, even when single, exceed a walnut in dimensions ; when very numerous, they are sometimes scarcely larger than pins' heads, and some, of these small dimensions, * London IMed. Chir. Journal, vol. iv, t Morgagni de Sed. &c. Ep. 37, § 19. X On Angina Pectoris, p. 240. § Save, Joum. des Savans, Sept. 1697. Baillie, Morbid. Anat. Sj mav be associated with others of far greater bulk. Their form likewise varies to a certain extent with their number. When single, the spherical, oval, or elongated shape predominates ; when numerous, they press upon and mould each other into cubic, pentagonal, or polygonal figures, with obtuse and rounded angles. Their most common colour is greenish yel- low ; but various shades of brown, green, dark or canary yellow, and even black or white, are observed. Their colour frequently varies in different parts of the mass ; and the differences of hue may either correspond to the lamellae of the calculus, or to the matters acting as the nucleus and the cortex respectively (the most common case), or be irregularly observable over the surface so as to produce a mottled appearance. Biliary calculi have a smooth surface and slightly unctuous feel. When a biliary calculus is broken across, a distinction of nucleus and cortex is very com- monly seen. Complete homogeneousness, with- out any lamellar or other obvious arrange- ment, is extremely rare. The cortical portion generally consists of dull-looking lamellae ar- ranged concentrically, but also striated trans- versely. A tendency to the alternating charac- ter of urinary calculi is sometimes visible : thus in the central [)oint may appear a dark coloured and homogeneous matter in small quantity (bile pigment), and from this shining strata (cholosterin ) radiate tow ards a cortex such as that above described {fig. 87.) The thickness of the cortex va- ries in different parts; though Fractured surface generally greatest at the of ahiliary cal- angles of polygonal calculi cuius. (fig' S'^)) this is not alway.s the case. In a few instances on record a foreign body (e.g. a piece of needle) has been found forming the nucleus of a biliary calculus; such cases are of singular rarity, however, and for obvious reasons. The constituents of biliary calculi are cho- lesterin (the chief one) with other kinds of fat in small proportion, choleate of soda, bilifel- linic acid or biliary resin mixed with bile pig- ment, epithelium, and mucus. In some cases the mass is almost wholly composed of colour- ing matter * ; in others of biliary resin and modified colouring matter, with mere traces of cholesterin.-|- Berzelius describes a gall-stone composed principally of carbon. Von Bibra J discovered 1.5 per cent, of alumina with iron, and 1,4 per cent, of carbonate of lime in a biliary calculus ; the latter salt was also de- tected by Witting in considerable amount. A calculus analyzed by Bally and Henry :|: con- sisted of carbonate of lime with traces of car- bonate of magnesia 72.70, phosphate of lime 13.51, mucus with a little peroxide of iron and * Arcliiv. der Pharmacie, Bd. xli. S. 291. t Simon, loc, cit. p. 470. X Eod. loc. G 3 86 PRODUCTS, ADVENTITIOUS. bile-pigment 10.81. Bertazzi* maintains cop- per to be a constant ingredient of biliary calculi, having found it in every one of fourteen speci- mens, apparently to an amount varying directly as the quantity of colouring matter present. Heller f confirms the statement of this chemist. Bertazzi failed in detecting copper in the bile collected from the gall-bladders of ten persons. In very rare instances calculi have been found composed of inspissated bile. Mr. Taylor J discovered a calculus in the collection of the College of Surgeons, pre- sumed to be biliary, and composed of the stea- rate of lime. It floated in water, and had a lamellar structure ; the lamellae being easily separable and alternately of white and reddish yellow colour. In the centre was a small cavity. The analysis, justifying the above view of its composition, is given in full. This rare description of calculus appears to signify a stage of transition from the common cases to those instances in which the biliary passages contain masses composed essentially of car- bonate and phosphate of lime, especially of the former salt. Richter describes a case in which the liver contained a multitude of such bodies varying in size from a pea to a cherry. Matter of this kind is occasionally found coat- ing the gall-bladder and ducts ; and in the interior of cysts in the substance of the organ. (Baillie and Zannini.) (/.) Pancreatic. — Calculi of the pancreatic duct have been observed in rare instances by Matani, Eller, Bium;, Galeati, and others. Baillie found some as large as a hazel-nut, of white colour and irregular surface, which Wol- laston ^ showed were composed of carbonate of lime. Fig. 88. represents a portion of a dilated pancreatic duct, which contained an enormous number of small calculi (such as are seen within it in the sketch) of dull white colour, perfectly round, varying in size from that of a pin's head to that of a small pea, elastic and hard. Fis. 88, Pqincreatic calculi, natural size. ( Univ. Coll. 3Ius. Pancreatic calculi have not, as far as we are aware, been found in the intestine in transitu outwards. (m.) Seminal. — Calculous masses have oc- casionally been detected in the vesiculae se- jninales and ejaculatory ducts. || Collard de Martigny found some composed of mucus and coagulated albumen chiefly, with a small quan- * Polii, Annali di Chemica; Milano, Juglio, 1845 t Archiv. vol. ii. p. 228. j Lond. and Ediiib. Phil. IMag. 1840. § Pemberton, Diss, of the Abdom. Viscera, p. 68. II Hartmann, De calc. in vesic. seminal. Erfurt, 1765. tity of calcareous salts.* These calculi some- times accumulate in vast numbers ; thus two hundred were discovered in the right vesicula seminalis of a man aged fort3-five -f ; no symp- tom had occurred during life connected wath the organ. (??.) Mammary. — The lactiferous ducts are occasionally the seat of minute calculous bodies ; Gooch, Haller, Reil, and others report cases of the kind. Morgagni alludes to their existence in the breast of a gouty person. The history of the case generally connects their production with the function of suckling, and sometimes with obstruction of the flow of milk. (o.) Vagijial and pudendal. — Calcareous ac- cumulations in these parts are not extremely rare. They originate in a deposition of phos- phates around some foreign body; a pessary for example, or around a nucleus of thickened mucus accumulating either from habits of un- cleanliness or from malposition of the uterus. Kohler discovered five large chalky-looking masses, weighing together more than seven ounces, in the vagina of a woman, aged forty, affected with prolapsus uteri. (/?.) Uterine. — The internal surface of the uterus is in rare instances found more or less extensively lined with, or studded with rounded masses of, saline matter of variable consistence. This condition has been observed in cases of deviation of axis of the uterus ; the saline matter is in all probability composed mainly of phosphate and carbonate of lime. (B.) Concretions or Pseudo-calculi. — Concretions are masses composed of saline materials deposited in a pre-existing organic basis, — the former, as they increase, gradually encroach on and, as it were, dispossess the lat- ter, until eventually, in many instances, all ob- vious traces of its existence have disappeared. The saline matters are commonly deposited punctatim ; and the organic basis, in which they accumulate may be non -stromal (as, for example, tuberculous matter, atheromatous matter, &c.), or stromal (as, for example, fibrous tumour, &c.) And, again, the natural textures (as, for instance, cellular tissue, tendon, &c. in the case of tophaceous con- cretions) ; the solid elements of the cir- ^ culating fluid (as the fibrin of the blood in ' the case of phleboliths) ; and, lastly, various adventitious]substances (as those mentioned ) above), may severally act the part of that organic basis. {a.^ Elementary cell. — Perhaps the sim- plest form of true concretion is that in which an epithelium-cell becomes coated or studded with saline material. We have seen this con- dition in the epithelium lining adventitious cysts, in the epithehum floating in pleuritic efllisions, and occasionally in that discharged with the urine. The concretions, not very un- commonly found in the choroid plexus, con- sist of round cells coated with calcareous salts. Flakes of albuminous substance may some- * Journ. de Chim. INIed. t. iii. p. 133. t Archives de Me'decine, Juin, 1831. PRODUCTS, ADVENTITIOUS. 87 times be seen in the urine coated with saline matters ; but this is merely a rudely analogous condition to those previously mentioned. (b.) Fcetal (petrifactions).— At the opposite extreme to cases in which a simple elementary cell becomes the depositary of calcareous mat- ter, stand those remarkable instances in which an entire individual becomes more or less com- pletely invested with a coating of such matter ; while subsequent desiccation of the tissues (with, very rarely, partial calcification of these) mummifies the entire frame. (c.) J'/amzte/.— Calcareous concretions are of not uncommon occurrence in the human placenta. Hannover found them in large number in twenty of two hundred placentiE. They are of white colour, rounded or branched in shape, and composed of phosphate of lime : generally seated on the uterine, rarely on the fcetal, surface, near the border. The age and constitution of the mother or of the child, separation of the placenta, and haemorrhages, appear to Hannover to be without influence on their production. ( d. ) Vascular. ^Arteries. — ( I .) Parietal. — There are few conditions more familiar to the observer than the calcareous deposition in the coats of arteries, long erroneously styled " ossification " of these tubes. The saline materials, giving the ossiform aspect to the de- position, assume four different forms: 1. That of a gritty looking substance sprinkled over the internal surface of the vessel; 2. That of patches of variable size and thickness, some- times sufficiently extensive to convert a con- siderable tract of the vessel into an inflexible tube ; 3. that of small rounded or shapeless masses, protruding or not into the interior of the vessel ; 4. that of prominent spiculae ; when their anatomical constitution appears more allied than under other circumstances to that of bone. Mr. Brande found these incrustations to consist of sixty-five and a half per cent, of phosphate of lime and the rest of animal matter. These proportions must of course vary in different cases : thus Scherer * found " ossified " arterial membrane composed of — Organic matter 7.292 Phosphate of lime 63.C3G of magnesia.. 10.909 Carbonate of lime 18.181 M. Bizot f has given a tabular view of the relative frequency with which different parts of the aorta become the seat of this condition ; and from this we learn with more precision than could be otherwise attained, that the points at which the different branches are given off" are far the most frequently im- plicated ; and that the posterior surface of the thoracic and abdominal divisions of the vessel suffers more frequently than the anterior in the proportion of 11 to 1, The precise seat of calcareous deposit, in respect of the coats of the tubes, has been * Simon, loc. cit. p. 477. \ Mem. de la Societe Med. d'Observation, t. i. made matter of much disputation. We have ourselves found that in the aorta the new matter is thrown out between the middle and internal coats, and in the vessels of the limbs either in this situation or in the actual sub- stance of the middle coat ; — or, to use the language which the modern anatomy of arte- ries would require us to adopt, we should say that the saline matter is deposited in the aorta in the striated and longitudinal-fibrous tunics between the epithelial and circular-fibrous tunics; and also, in the arteries of the limbs, in the substance of the circular-fibrous and true elastic coats. There are three kinds of deposit, of com- mon occurrence in the arteries, set down by writers as the nidus in which saline accumu- lation may occur: these are the" atheromatous matter," the " white spot," and the " cartila- ginous patch." The origin and nature of these matters require to be briefly examined. The atheroma of the arteries and cardiac valves is a yellowish matter occurring in minute^ particles, hardly larger than grains of sand ; separate or clustered into small patches ; most abundant at the points where vessels are given off' from the affected trunk; obviously seated underneath a coating of epi- thelium, and even probably under the striated tunic of the artery, (as when an attempt is made to peel it away by raising these two coats, it is in part removed with them, and remains partially adherent to the deeper- seated tunics) ; and distinctly unctuous to the feel, when accumulated in any quantity. The substance is indeed of fatty nature. Gluge * found that " an enormous deposition of fat globules solely and alone constitutes this mor- bid state, and in fact even with the naked eye a remarkable similarity may be perceived be- tween the atheromatous state and certain forms of fatty deposition in the liver." Mr. Gulliver -j- has independently ascertained the same fact, and illustrated his description by figures.;}: The researches of M. Bizot have very clearly established that this atheromatous matter be- comes, with the progress of things, the seat of one or other of two series of changes, termi- nating in the one instance in ulcerous soften- ing, in the other in calcareous deposition. The stages of the ulcerous softening are four : in the first the yellow matter becomes slightly prominent on the surface of the vessel, and the superficial fibres of the " middle " tunic lose their natural consistence ; in the second the internal membrane is raised into little emi- nences by the accumulation of a matter which is sometimes liquid and puriform-looking, sometimes floury and dry, and occasionally containing minute shining scales, some of * Anat. IMicros. Untersuchungen, Erstes Heft, S. 130, 1838. t Med. Chir. Transactions, vol. xxvi. p. 86, 1843. X We have occasionally found plates of cholesterin in greater abundance than oil-giobules, — a fact having an obvious connection with the established circumstance of the excess of _cholesterin in the blood of old persons. G 4 88 PRODUCTS, ADVENTITIOUS. which have a white and silver}' look (choles- terin). In the third sta<^e depressions with a smooth surface, (except in the points where the lining tunic has undergone fissure for the evacuation of the matter described,) mark the previous seats of tliis matter. The fourth stage is distinguished by the disappearance of the lining membrane in the afiected points, and hence by actual excavation. Neither suppura- tion nor injection attend the changes reviewed. When the atheromatous matter undergoes the calcareous change, a liard but minute point comm.only appears in its centre; this gradually increases, especially in breadth, the middle coat being earlier implicated than the lining tunic, which is occasionally covered with con- crete fibrin. Eventually the lining coat is de- stroyed, and the concretion brought into con- tact with the blood ; the middle coat rarely becomes affected through its entire thickness. The deposition may commence in a multitude of minute points simultaneously, whence the atheromatous matter acquires a gritty feel. The white and cartilaginiform patches are not in any instance the nidus of the saline deposit, according to M. Bizot ; at least he has never succeeded in tracing the early pro- cesses of deposition in those patches. Nothing, however, he admits is more frequent than the deposition of atheromatous and subsequently of calcareous matter underneath the "cartilagi- nous " patch, which is occasionally perforated by the calcareous substance, and an appear- ance pro'luced easily explaining the current opinion that the patch in question is the ori- ginal seat of the saline particles. We agree with M. Bizot that the " cartilaginous" patch is altered plastic matter exuded on the inner surface of the vessels. Mr. Gulliver has, it is true, discovered fat-globules and crystals of cholesterin in the " w hite patch " of vessels ; but the circumstance appears explicable in the manner just referred to as resulting from the French author's inquiries. In the arteries of the limbs calcareous depo- sition may likewise commence in the middle coat itself, which becomes harder and thinner as the disease advances. It is important to observe that the close examination of calcareous plates through their various phases of development demonstrates, as we have seen, their independence of inflam- nmtion. Calcareous deposition is remarkably depen- dent upon age. Bichat calculated that the arteries of seven of every ten persons beyond the age of sixty were thus affV-cted ; while its existence is extremely rare in early youth. Writers have indeed maintained the perfect immunity of the vessels of youthful subjects from this change : but Mr. Young found the temporal artery of a child fifteen months old converted into a calcareous cylinder; Otto* once discovered incij)ient ossification of the aorta in a girl of seventeen; Wilson met with a similar condition in a child three years old; Andral in a girl aged eight; and numerous * Patholog. Anat., by Scuth, p. 333. other instances of the kind are recorded. Cal- careous deposition is more common in vessels of a large than of a small calibre, and espe- cially in the aorta; rarer in the upper than the iower extremities ; it sometimes extends through the entire arterial system of the trunk and lower limbs, — we have before us the ves- sels of a subject in this condition, who died with gangroena senilis.* Such disease never occurs, according to Otto, in the arteries of the thoracic and abdominal walls, and perhaps those of the alimentary canal and liver ; and is, on the contrary, common in those of the pelvis, of the brain, of the thyroid gland, the heart, the spleen, the kidneys, &c. The pul- monary artery is, comparatively speaking, con- sidered exempt from calcareous deposition : several instances, however, are referred to by Otto, in which it was more or less completely "ossified;" it is not unfrequently so where the right and left cavities of the heart com- municate, (but here the vessel is placed in re- spect of its contained fluid in the state of an ordinary artery). Hope f attended a lady, aged 60, in w hom the " pulmonary artery was found quite ossified where it plunged into the lungs ;" and from our own records of cases we know that slight alteration is not very uncommon. The close comparison of corresponding ves- sels on the two sides of the body has led M. Bizot to the discovery that not only the same vessels, but the same parts of these, are, with the rarest exceptions, affected with the same alterations of structure, — that a law of sym- metry regulates the development of these. Upon this point much curious information will be found in M. Bizot's admirable essay. Calcareous deposition is common in the ar- teries of syphilitic subjects, and of those who have taken mercury to excess. ISIuch fanciful hypothesis has been indulged in respecting the influence of certain kinds of diet on its pro- duction. This morbid state destroys the elasticity of the arteries, renders them fragile, and inter- feres with the circulation ; we have known it lead to rupture of the aortic valves. The cal- careous matter protruding more or less into the vessel affords a centre for the blood to coagulate around, and may lead to its com- plete obliteration, — a result which it would appear may be produced by mere thickening of the coats ; in either case suspension of the circulation and gangrene are the results. " Ossification " of the coronary arteries of the heart has been met with in cases of angina pectoris (recently by ourselves) and of sudden death, — probably rather acting as the occa- sion, than the cause, of both. (2.) Central. (Arterolit/is.) — Calcareous concretions, free in the interior of the arteries, are as rare as the conditions which we have just described are common. OttoJ saw in the Copenhagen Museum " a round stone as large as a pea," said to have been taken from the * Univ. Coll. Mus. t Diseases of the Heart, 3rd ed., p. 589. X Path. Anat., by South, p. 335. PRODUCTS, ADVENTITIOUS. 89 sspermatic artery ; but he believes it to have })robably been of venous origin. Eight loose stony concretions have, he observes, been met with in an aneurismal sac*; the largest of these was as big as a plum. Landerer has recently analyzed an aortic concretion, which contained 14 per 100 of uric acid.l Veins. — Parietal concretions are as rare in the veins as common in the arteries ; central concretions as frequent in the former as rare in the latter vessels. (1.) Parietal. — These are in truth of ex- treme rarity in the veins. That they do occur, however, and with somewhat greater frequency than is admitted by speculative writers, is cer- tain. An example of" ossification" of the co- ronary veins is related in the Ephem. Nat. Cur. Dec. iv. An. x. Obs. 175; CruveilhierJ once found the popliteal veins studded with ossifications similar to those existing in the accompanying arteries ; not a few examples of " ossification" of the vena porta are on re- cord^ ; Morgagni and Baillie found the vena cava inferior in a similar state, &:c. In many cases of the kind there appears to have been calcification of the parts immediately adjoining the vessels. The sort of antagonism existing between the arteries and veins, in respect of parietal con- cretions, has been referred by Bichat to differ- ence of structure of the lining membrane in the two classes of vessel ; by Bizot to the dis- similar properties of the blood circulating in them ; by others, who regard the deposition as evidence of decay, to the greater activity and consequent earHer exhaustion of the arte- rial tubes. None of these notions are unopen to objection. (2.) Central. — Central concretions in the veins (pheboliths, from (pxe\i/, a vein, and At0os, a stone,) are generally of ovoid or rounded shape ; vary in size from a pin's head to a pea and upwards, in rare instances attaining the bulk of a hazel-nut, and in weight average about a grain or a little more at most ; are of low specific gravity; occur singly or in num- bers varying from two to ten and upwards ; are either perfectly free, or adherent to the internal surface of the vessel either directly or by means of a slender peduncle (these three conditions may be observed in the same vein) ; are smooth on the surface, and (whether partly sanguineous or wholly calcareous) invested with a dehcate membrane of serous aspect. These concretions are unquestionably by far more common in the veins of the pelvic viscera (the spermatic, the ovarian, the vesical, the haemorrhoidal,) than in others. They are not unusual in the splenic veins, and have been met with in the renal, mesenteric, prostatic (thirty were found in the latter by Ehrmann || ), and pubic veins ; they have been seen twice * Biermayer, Mus. Anat. Path. p. 101, No. 360. t Med. Gazette, July, 1847. X Essai sur I'Anat. Path. t. i. p. 70. § Ruysch, Thes. Anat. No. 58 ; Meckel Path. Anat. Bd. ii. Abth. ii. S. 190. II Compte Rendu des Trav. Anat. &c. p. 38, Strasb. 1827. by Cloquet in the vena cava inferior. They occur sometimes in varices of the lower ex- tremities * ; Dupuytren found them in the anterior and posterior tibial veins ; but they have not, so far as we are aware, been seen in the veins of the arms. Gmelin -|- found them composed of Animal matter 27.5 Phosphate of lime 53.5 Carbonate of lime 15.5 Magnesia and loss 3.5 100.0 The part of the vein containing a phlebolith is sometimes much dilated, and eventually the vessel may become obliterated above and below the obstruction. Lobstein conjectures that the new formation with its investing portion of vein may be altogether separated from its con- nections ; and, in the case of the haemorrhoidal veins, passed by stool. Hodgson supposed that these bodies were first formed external to the vessel, and subse- quently made their way into its interior ; An- dral that their original seat was the substance of the walls of the vein. The occasional existence of a peduncle does not, as has been presumed, really warrant these notions ; as it may no doubt be formed either of fibrin or of plastic matter (thrown out by the tunics from secondary in- flammation) coated with epithelium. Besides, the absence of marks of rupture of the surface further confutes them. It was suspected by Cruveilhier;}:, taught by Lobstein§, and proved by Carswell||, that phleboliths originate in clots in the interior of the vessels. The following is the series of changes observed : — stagnation occurs; a clot forms; loses its red colour; becomes concentrically stratiform ; acquires fibrous consistence, and gradually grows calca- reous and indurated, stratum by stratum, from the centre outwards, until the whole mass ac- quires almost stony hardness. Dr. John Reid^ regards the process of induration as one *' re- sembHng the formation of osseous tissue in other parts of the body a view invalidated by the absence of true cartilaginous matrix, or of osseous texture at any period of the evolution of the bodies in question. (e.) Li/mphatic and lacteal. — Althoueh it is possible that the extreme rarity with which the lymphatic and lacteal vessels have been found to contain calcareous matter may in part de- pend upon those vessels being seldom ex- amined, yet it is certain that such condition is really singularly uncommon. Cheston Browne** refers to a casein which the entire thoracic duct from the receptaculum upwards was "ossified" and obliterated. J.D. Scherbtf * Bouillaud, Rev. Me'd. Avril, 1825. t Tiedemann's Zeitschrift, Bd. iv. XL i. 1831. Essai, t. i. p. 71. An. Path. t. i. p. 505. II Fascic. Anal. Tissues. «j[ Ed. Med. and Surg. Journ. No." 123. ** Phil. Trans, vol. Ixx. p. 323, 1780. ft De calculo in due. thorac. 1729; Haller's Diss. Path. 90 PRODUCTS, ADVENTITIOUS. has described a concretion found in the tho- racic duct. The lymphatics of the small in- testines have been found in this condition by Walther.* The lymphatic glands, especially the bron- chial and mesenteric, are, however, not unfre- quently the seat of calcareous precipitation in points, patches, or through their entire sub- stance ; it chiefly occurs in connection with tuberculous disease. (/) Serous and synovial cavities. — These cavities occasionally contain calcareous pro- ductions, evidently produced by the deposition of saline matter in a pre-existing organic basis. This basis, commonly effused fibrin (when the concretion has been free from the moment the process of saline deposition com- menced), has in other instances been the sub- stance of fibrous tumours once attached be- neath the serous membrane, and accidentally set free. (g.) Similar bodies are occasionally found in connection with the fibrous membranes. Andralf describes a very interesting case of tumour of this kind attached to the tentorium cerebelli. {h.) Cerebral. — A concretion taken from the brain analyzed by Lassaigne;|: was found to be composed almost wholly of fibrin, of a small quantity of cholesterin, and of 4 per cent, of phosphate and carbonate of lime — the evi- dent, though rare, result of previous hsemor- rhage. A concretion from the cerebellum, exa- mined by Simon j^, about the size of a nut, of irregular angular form, very solid, both inter- nally and externally resembling a piece of bone, and enveloped in a fine coriaceous capsule, con- sisted principally of phosphate and carbonate of lime with a little cholesterin. A similar concre- tion analyzed by John consisted of 75 parts of phosphate of lime and magnesia, and 25 of animal matter ; another examined by Morin was composed of cholesterin, coagulated albu- men, and earthy phosphates. (i.) Uterine. — Much confusion has arisen from want of accurate distinction of the diffe- rent kinds of saline deposition occurring in the uterus. These kinds, we hold to be, three in number. 1. The internal mucous surface may be coated with phosphatic salts. 2. The parenchyma of the organ may contain " ossi- form " (really calcareous) globular masses re- sulting from the deposition of saline matter in the interior of fibrous tumours. 3. The uterine tissue may be the seat of phosphatic accumulation around foreign bodies. These bodies may be either introduced {a) from with- out, or (b) enter the uterus from some other part of the genital system, (a) Of the former case Brugnatelli records a curious instance. A calculus weighing about two ounces, of rough surface, and composed of phosphate of lime, was removed from the uterus of a young peasant, and on division found to have a small * Mem. de I'Aoad. des Sciences de Berlin, 1786- 87, p. 21. t CI. Me'd. t. V. p. 8. X Journal de Chim. Med. t. i. p. 270. § Loc. cit. p. 474. piece of the tibia of a fowl for its nucleus, — broken off, no doubt, from the entire bone, which had been introduced per vag!nam,for the purpose of inducing abortion, (b) Fragments of foetus derived from extra uterine pregnancy, as also moles and hydatids, occasionally form the nucleus or basis of saline concretions. The Fallojnan tubes, too, sometimes contain calcareous concretions. Walther had in his possession a globular calculus of yellowish co- lour, a third of an inch in diameter, weighing ten grains, taken from the left Fallopian tube of a woman aged forty. It is extremely pro- bable, though not proved by examination, that these masses are, in some instances at least, the remains of fibrous tumours. (k.) Pulmonary concretions. — The pulmo- nary parenchyma is an extremely frequent seat of concretions. The basis, in which the saline material accumulates, is by far the most fre- quently tuberculous ; more rarely the fibrinous substance of simple inflammatory exudation forms its nidus : numerous points of interest are connected with these kinds of concretions, and will be more fully referred to in the section on tubercle. Cancerous substance in the lung may become locally infiltrated with saline sub- stances ; we have not known such change to occur in blood effused in this parenchyma. The appendages of the lung are likewise among the habitats of concretions. Fibrinous exudations in the pleura occasionally form the basis for simple saline precipitation ; or less frequently of an ossification-process. The bronchi become in very rare instances more or less completely blocked up with solid concre- tions, the organic basis of which, in the majo- rity of instances, is not improbably (but this point requires further investigation) that mate- rial holding a medium position between diph- theritic deposit and common inflammatory exudation matter, which constitutes the anato- mical character of " plastic bronchitis." In a case observed by Gorup-Besanez*, such, how- ever, could not have been the origin of the saline accumulation, — at least presuming the chemical analysis to have been correct. Here a coral-like " ossification " was found in the bronchi of a man aged forty-five, as thick as a crow's quill, and extending through the whole length and breadth of the lungs. It broke with a crack; whether it was hollow or not, we are left to conjecture. On analysis it furnished Fatty matters and traces of soluble salts 17.17 Mucus 32.46 Phosphate and carbonate of lime, with traces of oxide of iron 50.37 (/.) Arthritic. — The substances termed tophi or gouty concretions belong to the pre- sent class. Variable in shape, rounded or tuberculated ; of yellowish white or brownish red colour externally, internally white ; vary- ing in consistence from soft toughness to very considerable hardness; sometimes unctuous to the feel; and apparently enveloped in a * Heller's Archiv. Feb. 1846, or Medical Times, 1S46 ; also Ticc, in Med. Chir. Trans, vol. xxvi. PRODUCTS, ADVENTITIOUS. 91 delicate membrane; these productions form within the laminee of the capsules of the joints of the hands and feet, sometimes in the sur- rounding cellular membrane, and least com- monly in the tendons. Their substance has a chalky look on section. Their chemical constitution was first made out by Fcurcroy and Wollaston; most cor- rectly by the latter. Urate of soda forms their main saline constituent ; with this is as- sociated urate of potash and hme in small quantity, chloride of sodium in good propor- tion, and animal matter. A gouty calculus from the metacarpus of a man aged only twenty-two, examined by Lehmann, presented innumerable four-sided prisms, arranged in stellar groups, consisting of urate of soda. The composition was as fol- lows : — Urate of soda 52.12 Urate of lime 1.25 Chloride of sodium 9.84 Phosphate of Hme 4.32 Cellular tissue 28.49 Water and loss 3.88 The abundance of nr-ate of soda in these calculi is a very remarkable feature in their con- stitution ; and points to the probability of that salt existing in the blood of gouty patients. (m.) Cutaneous. — The natural secretion of the sebaceous glands may be retained within those sacs in consequence of accidental closure of their orifices. And if the saline materials predominate much over the organic, either as a fault of original secretion or from inspissa- tion, a concretion is the result. Epithelium and fatty matters of various kinds are always associated with the saline materials. These saline materials, which vary much in their per-centage quantity, are mainly phosphate and carbonate of lime. SUB- CLASS II. ANIMALIZED PRECIPITATES. The distinctive character of products of this sub-class is, that they are exuded ready formed from the vessels ; when (ceasing to mix with, or precipitated from, the blood) they appear as "products " outside the vessels, they possess as much of the attributes of organization as they are ever destined to acquire. The ele- ments composing them are organic ; but these elements are either by nature incapable of forming structure, (as sugar, oils,) or circum- stances deprive them of the power they natu- rally possess of developing a structure (as cer- tain protein-compounds) : they are distinctly non-plastic. The animal substances enumerated, when exuded from the vessels, always form ( what may be called) potentialli/ the material of pre- cipitates ; but circumstances occasionally pre- vent the actual formation of these. The morbid process essentially consists in exuda- tion (secretive or other) from the bloodves- sels — this is the theoretical precipitation. It would be a needless refinement to make a subdivision of actual precipitates and non- precipitated potential precipitates. § I. Protein-Compounds. — When oc- curring as actual precipitates, the protein- compounds appear as minute microscopical particles, amorj)hous or granular ; they absorb readily the ioduretted solution of iodide of potassium, and become of yellowish brown colour; they are insoluble in aether, altered but not dissolved by acetic acid, insoluble in mineral acids, and dissolved by maceration in caustic alkalies. (A.) Albumen. — Of the so-called protein- compounds albumen is by far the most fre- quently observed as an adventitious product belonging to the present division. It is either (fl) thrown off with certain secretions (of which it forms no part in the natural state ;) or (b) it is retained in a stfuetareless o^4ion-organi- zable condition. /<>~^l^^^ — — ^ - - ,\ (rt.) Albunienun ^he secretions. — Or these the most important -is the urine. Thiii fluid, as discharged fron^iltelitadder, is found, in a considerable variety ofT^Tal-dtseases' or general derangements of the system, to be impreg- nated either temporarily or more or less per- manently, either slightly or abundantly, with albumen.* The various conditions under which this impregnation occurs were classed several years ago by us in the following man- ner ; the advance of knowledge has in the intervening period rendered scarcely any change necessary. M. Martin- Solon's term Albuminuria may be conveniently used to signify the discharge of albuminous urine ge- nerally; but cannot be logically used as a synonym of (nor even as a convertible term for) the affection known as " Bright's Disease." Albuminuria may be caused b}^ — First : An imnalural state of the blood. Se- condli/: j\ forbid states of the genito-urinary organs, either functional or organic, and when organic, either causing albuminous impreg- nation during, or subsequently to, the act of secretion. Thirdli/ : Accidental admixture of genital p7'oducts. Fourthly: Some cause hi- therto unestablished. A few remarks on these various conditions are absolutely called for. First : Albuminuria from an unnatural state of the blood. Dr. Blackall, in his work on dropsies, has related cases of scorbutus and petechiee in which the urine was coagulable ; but as the condition of the kidneys was not inquired into, the narratives are unsatisfac- tory. M. Rayerf , however, states that he has found the albumen and red corpuscles of the blood jDass occasionally into the urine in cases of scurvy, purpura, and haemorrhagic fevers ; while the fibrin diminishes in the vessels, and the watery portion becomes infiltrated into the cellular tissue, or exhaled on membranous sur- faces. Traces of albumen were discovered by Heller J in the urine of a girl aged nineteen, * Some chemists believe that urine natvirally contains albumen, though in proportion so small as not to be reached by existing means of analysis ; among these chemists rank Henry, Chevalier, and Dmnas, (Le^on sur la Chiniie Statique des etres organise's, p. 39.) t Maladies des Eeins, t. i. X Ai-chiv. fur Chemie, Bd. i. S. 12. 92 PRODUCTS, ADVENTITIOUS. independently of red corpuscles, in a case of purpura. In the worst forms of malig- nant haemorrhagic fever, however, no trace of albumen may be discoverable, — a fact recently exemplified in our wards at Uni- versity College Hospital. — The notion that purulent deposits may be carried off through the kidneys is one of long-established popu- larity among surgeons ; Ambroise Pare, De- sault, and others held the doctrine : the fact is, however, far from being established. M. Rayer has for some years sought in vain for pus in the urine of individuals, in whom the absorption of purulent depositions of various kinds was effected under his own immediate observation. An abundant precipitation of phosphates with mucus and epithelium will, as we have ourselves witnessed, sometimes produce an appearance most strangely like that of pus, — the microscope and the addition of a little acid readily settle the nature of the de- posit. Pus may, however, actually appear in the urine in cases of secondary abscess from purulent impregnation of the blood ; but it is then produced, we believe, in the renal struc- tures themselves, and is not composed of the originally formed fluid translated (with its pro- perties unaltereJ) through the circulating sys- tem into the renal passages. It is for this reason that the narratives of cases of " ab- sorbed empyema" (with elimination of pus, in substance, through the kidneys,) are, without the test of actual examination of the kidneys, altogether unsatisfactory. — Cotunnius* en- deavoured to explain the presence of albumen in the urine of a dropsical patient, whose anasarca was rapidly diminishing under the use of diuretics, by supposing it due to the direct passage of the serous fluid through the kidneys. But he had not established the ab- sence of albumen from the urine, before diuresis set in ; M. Rayer (as also we our- selves), avoiding this source of error, has failed in detecting albumen in urine, passed concomitantly with the disappearance of drop- sical effusion, whenever the fluid had pre- viously been free from that principle. Secondly : Albuminuria from morbid states of the genito-urinary organs. (1. Functional.) On the presence of albumen in cases of simple hfematuria it is only necessary to observe, that the albuminuria rarely persists for more than a few xlays after the discharge of blood-disks has ceased ; concerning its appearance in dia- betic urine, we shall presently have occasion to speak. (See Sugar.) — The urine of healthy individuals may become albuminous for a short while (for instance, four-and-twenty hours,) after direct or indirect excitement of the urinary passages. We are not quite sure of being right in ascribing the action of certain articles of food and medicinal agents to such intermediate irritation of the kidneys ; it is perhaps equally tenable that an altered con- dition of the blood is, in these cases, the direct cause of the excretion of albumen with the * De Ischiade Xervosa Comment. Yiennie, 1770, p. 30. urine. Dr. Christison* "has occasionally known a temporary albuminous impregnation produced in healthy individuals by eating freely cheese, pastr}-, and such other indigestible articles as are known to have in general the effect of increasing the usual solid ingredients of the urine, and occasioning a large deposit of lithic acid and lithate of ammonia." We agree with M. Martin- Solon -|- that when such consequences follow, individual predisposition must be admitted to exist. Dr. Christison has repeatedly seen the same condition of the urine induced for a time (and we have ourselves had cognisance of the same fact) by the action oF a cantharides blister, when it excited symptoms of renal irritation, — That hyperaemia of the kidney of the simple kind may produce albu- minuria, was very strongly maintained by M. Martin- Solon, on the evidence of cases which wanted but the test of post-mortem examina- tion to render them conclusive : the valuable experiments of jNIr. Robinson give full war- ranty to the opinion. (2. Organic.) — It may be considered as yet undetermined clinically, whether the urine becomes albuminous in cases of simple nephritis unattended with any of the anatomical changes peculiar to "Bright's disease ;" if it does so, the impregnation is not constant, and is slight in amount. J — The connection of albuminuria with the disease cf the kidney described by Dr. Bright is, on the contrary, after much disputation, thoroughly established. While the error of supposing mere albuminous impregnation pathognomonic of that affection is, on the one hand, perfectly understood ; on the other, the great import- ance of permanent albuminous impregnation, as a sign of the disease, is recognised. We have never ourselves seen a case of Bright's disease in which the urine was permanently free from albumen § ; but the amount to which it is present is, of course, extremely variable ; we have frequently treated cases in which the coagulation was so complete, that not a single drop of fluid escaped, when the test-tube was turned upside down after ebullition. — On the various affections of the urinary passages causing impregnation subsequently to the act of secretion {e.g. pyelitis), it is unnecessary to dwell ; of albuminuria depending on ence- phaloid disease of the urinary organs, we have spoken in another work.|| Thirdly : Albuminuria from accidental admix- ture of genital products. The urine becomes impregnated with semen under a variety of circumstances. The secretion of the testes * On ccraniilar Degeneration of the Kidnevs, p. 36, 183"9. t De FAlbuininurie, 1838. j Becquerel (Seme'iologie des Urines) found a little albumen in the urine in one of five cases of simple nephritis. § Dr. Graves (Dublin Journal of ^Medical Science, No. Ix.) maintains that the renal alteration may, however, exist without albumen appearing in the urine, — an idea to be explained probably, by the occasional temporary disappearance of that principle (as we have more than once seen) even in cases pretty rapidly tending to a fatal issue. II the Nature and Treatment of Cancer, p. 386. PRODUCTS, ADVENTITIOUS. 93 escapes into the urethra in certain cases of paralysis and in habitual spermatorrhoea ; and when the bladder is evacuated shortly after coitus (more especially in persons having stric- ture of the urethra) its contents carry with them a certain quantity of seminal fluid. We doubt that the prostatic secretion alone (the fact has certainly not been proved) leads to distinct albuminuria. Leucorrhoeal and cata- menial discharges produce it. FourtJily : Albuminuria from a doubtful cause. Cotunnius*, Cruickshank-t-, NystenJ, Andral, Rayer, Martin- Solon, Becquerel, and we our- selves, have found that the urine may contain a variable quantity of albumen during the pro- gress of acute diseases — a fact which is now matter of familiar clinical observation. M. Martin-Solon shows that the impregnation occurs in about y^-th of all cases ; this ob- server at one time held that the occurrence was of " critical'" signification, an opinion he has since correctly relinquished. — In certain chronic diseases, unattended with any organic alteration of the kidneys, the occasional oc- currence of albuminuria has been positively established : in disease of the heart by Dar. wall§. Forget 1|, and Martin-Solon ; in bron- chitis and disease of the intestines by the lattLT observer ; in aneurism of the ventral aorta by Dr. Morrison 1 ; in phthisis by Toulmouche**,and by ourselves, temporarily. Of the habitual occurrence of albumen m gouty urine, the evidence is insufficient. Becquerel found it in seven of eighteen cases of acute rheumatism, depending rather upon the acute tyj)e, than upon the nature, of the disease. — In the exanthemata, albuminuria depends on simple renal congestion (resulting from the inaction of the skin) ; or (especially in scarla- tina) on the supervention of a form of " Bright's disease," characterized by abundant accumulation of epithelium in the tubules. The saliva is another secretion which, con- taining albumen in extremely small quantity in the natural state (not more than 1.5 in 1000 parts), becomes apparently impregnated with that substance somewhat abundantly in certain morbid conditions. Simon f f found 7.77 per 1000 in the fluid discharged in ptyalism. However, the elaborate analyses of Dr. Wright J:}: show that this excess of albumen IS not a constant phenomenon ; in a case of ptyalism he found the albumen reach only 0.6 per 1000, and in three other forms of morbid saliva analyzed by hira (fatty, sweet, and bilious), the quantity of albumen equalized the average in the fatty variety only. The sweat has been found to contain albu- * Op. cit. p. 31. t Rollo on Diabetes, p. 444. X Re'cherches de Chim. et de Phvs. Pathologiques, p. 253. 1811. § Cyclop. Pract. Med. art. Dropsy. II Gazette Me'dicale de Paris, vol. v. p. 609. (two ca^es.) t Dub. Med. Journal, No. xxxvi. 1838. ** Gazette Med. de Paris. Fevrier, 1839. tt Op. cit. vol. ii. p. 10. XX Medical Times, or Der Speichel in Physiol. Diagnost. and Therap. Beziehung, 1844. men by Anselmino in a case of rheumatic fever. Stark asserts that albumen may be detected in this excretion in " gastric, putrid, and hectic diseases, and also on the approach of death, in consequence of the abnormal solution of the solid constituents." Simon ^ failed in de- tecting any certain indications of albumen in the sweat of a person in the colliquative stage of phthisis. (6.) Albumen retained. — That granular par- ticles of protein-basis, retained within the tissues, are some of them albuminous, seems a very admissible proposition. The non- plastic protein-substance infiltrating the kidney in certain forms of Bright's disease, for example, is albuminous rather than fibrinous in all pro- bability. But the difficulty of positively assign- ing their species to protein-compounds, espe- cially under such circumstances, is sufficiently well known. The mechanism of albumen-pre- cipitation within the body must be of different character from that by which it is effected without the frame, — at least it is not easy to conceive how the agencies, chemical and phy- sical, which are known to produce precipi- tation of albumen removed from vital influence, can come into play among the tissues. Albumen appears in the retained and non- plastic state as an important element in the fluid of dropsies ; to avoid repetition, we defer its consideration under these circumstances to Part II., where dropsical products are ex- amined. (B.) Fibrin, (a.) In the secretions. — That fibrin should occur in the urine, in association with the other elements of blood, is no more than must be expected in cases of haematuria. But it has of late years been found that fibrin sometimes occurs in solution in that excretion independently of any other constituent of the blood. Thus Nassef " knew a Catholic priest who passed, particularly during the night, a large quantity of whitish urine, that coagulated spontaneously in from ten to fifteen minutes after leaving the bladder, and often indeed coagulated in the bladder itself. The patient experienced no debility. On analysis the urine was found to contain a large quantity of fibrin, but no blood-globules." There were also prismatic crystals of triple phosphate present. Zimmerman :j: has particularly fol- lowed up this subject, and affirms he has dis- covered fibrin in the urine in endocarditis, pleuritis, pneumonia, bronchitis, rheumatic ophthalmia, periosteitis of the occiput, and erysipelas of the face. Urate of ammonia or uric acid was sometimes present. The fibrin, he presumes, appeared simply as an excretion, sufncient oxygen not having been taken up to decompose it into its organic forms. Zim- merman holds, that in cases of coagulable urine the coagulation will be found to be due to the presence of fibrin quite as often as of albumen, — a proposition which appears to us utterly inadmissible. * Op. cit. vol. ii. p. 109. t Brit, and For. Med. Keview, vol. xx. p. 75. X Zur Analysis imd Synthesis der pseudo-plas- tischen Prozesse ; or, Brit, and For. Rev. loc. cit. 94^ PRODUCTS, ADVENTITIOUS. (b.) Fibrin retained. — The majority of pro- tein-precipitates are probably fibrinous. At least spontaneous coagulation (a quality be- longing to them alone) is by far the most readily conceivable cause of precipitation under the circumstances now pointed at. Fibrin occasionally occurs as a potential precipitate in the fluid of dropsies, a fact which will be further considered in Part II. (C.) Casein occurs in combination with fat in so-called "milky" urine. (D.) Globulin is practically unknown (as distinguishable from the other protein-com- pounds) in the present point of view : it pro- bably forms the substance of some granular precipitates. § II. Fat. — Considered in respect of their ultimate physical elements, the varieties of fat (known to occur as morbid products) appear as adipose cells, free-fluid oil-globules (olein); solid fat granules (mainly margarin) ; groups of stellate crystals (margarin and margaric acid) ; rhomboidal plates (cholesterin). Fat may likewise be incorporated in such manner with the textures as to be only chemically discoverable, — a fact often lost sight of in the examination of morbid appearances : phos- phurelted fat has thus (among other examples of the fact) been found in cancer. Of serolin as a new product nothing is known. Unhealthy formation of fatty and oily sub- stance is of almost perpetual occurrence. The fat produced is either similar (when viewed with the naked eye) to that naturally filling the cells of adipose tissue, or more or less com- pletely dissimilar. In the first case the na- tural adipose structure is simply present in excess, whence arise local or general obesity., fatty infiltration of parts, and lipomatons tu- mours. In these conditions there is little more than hypertrophy or excessive secretion ; and it is mainly in deference to usage that we shall, in another part of this article, describe lipoma as an adventitious product. In the second case the dissimilarity of the fatty material to natural fat, or the new situation in which it appears, gives it the character of adventitious- ness. Here we shall find: (A) certain va- rieties of fatty infiltration of natural or of adventitious structures ; (B) fatty matters ex- creted in the semi-fluid state; (C) encysted felts; (D) cholesteric and laminated fats. (A.) Fatty infiltration, (a) Liver. — The existence of oily matter, as one of the natural constituents of the liver, long since proved chemically by Braconnot, was some years since established with the microscope, by Fig. 89. Nucleated particles from the healthy human liver. (After Bowman.) a, nuclei ; h, nucleoli ; c, fatty globules. Gluge*, and more recently with greater pre- cision by Mr. Bowman f, who displayed the position of the oil-globules in the elementary cells of the healthy organ. Now fatty infil- tration may occur from superabundant depo- sition of the natural oil, or from that of oily matter differing from this in chemical con- stitution. (1.) The liver, when "fatty," is increased, in some cases enormously, in size ; its rela- tions of shape remain unaltered. It is, by far the most frequently affected equally through its entire substance ; but we have, in rare in- stances, seen the infiltration specially impli- cating islets of the organ ; its colour is pale greenish yellow or faded leaf ; sometimes but rarely studded with reddish points ; its elas- ticity destroyed to such a degree that it pits on pressure ; its consistence greatly dimi- nished; its density decreased to so great an amount that slices have been known to float in water. Very rarely is this condition of the liver coexistent with other morbid changes in its substance ; the vessels and ducts are un- changed in calibre and structure. The fatty nature of the impregnation is sometimes obvious on the most superficial inspection ; the hands and knives broufjht in contact with the tissue are greased ; and if a thin slice be placed on paper and exposed to heat, the fatty matter melts abundantly, and oils the paper. Gluge was the first to show that these appearances depend upon the accu- mulation of a multitude of free fat globules, with a small quantity of yellowish granular matter, probably belonging to the colouring matter of the bile. Mr. Bowman discovered the precise seat of the morbid deposition to be the interior of the elementary liver-cells : " instead of containing a few minute scattered globules, the nucleated particles are gorged" with large masses of it, which greatly augment their bulk, and more or less obscure their nuclei." Fig. 90. Nucleated particles from the liver affected with fatty degeneration. (After Bowman.) a, nuclei ; b, nucleoli ; c, c, fatty globules. We believe, however, with Mr. Gulliver J, that in this morbid state fat accumulates " in the interlobular fissures and spaces, as de- scribed by Mr. Kiernan, or at least around the surfiice of the lobules, where it forms a distinct buff"-coloured boundary to each of them. The ruddy-coloured hepatic lobules appear to diminish in size as the paler fatty substance increases. In a few instances it was principally seated in the centre of the lobules." Albers^ taught that the fat depo- * Op. cit. Heft i. S. 126. 1838. Lancet, January, 1842. X Med. Cliir. Trans, vol. xxvi, p. 96. I Rust's Magazin, 1839. PRODUCTS, ADVENTITIOUS. 95 sition chiefly takes place in the interlobular cellular membrane which has first undergone hypertrophy : he confounded cases of cirrhosis with true "fatty" change. VauqueHn found that by exposing slices of fatty liver to a gentle heat, incapable of causing decomposition of animal matter, their composition, as the mean of several experi- ments, appeared the following : yellowish con- crescible oil, 0.45; parenchyma, 0.19: mois- ture, 0.36. This fat unites with alkalies, and forms a soft soap with the usual properties. From a specimen immersed in boiling water by Dr.Bostock*, a quantity of oil exuded, rose to the surface, and, when the water cooled, was converted into a hard white sub- stance, physically resembling tallow. It be- gan to melt at 80°, and was completely fused at about 110°; in its chemical properties it generally resembled tallow. Of the causes of this condition of the hver little is known. The fact of its frequent exist- ence in France in phthisical subjects, already stated by Bayle and Laennec, was numerically proved by Louis.f This observer foimd fatty impregnation of the liver in 40 of 120 phthi- sical subjects, in 9 only of 230 persons dying of other affections; he also discovered that (uninfluenced by age) its proportional fre- quency in males and females is as 1 : 4. An- dralj, speculating upon these facts, suggests that, inasmuch as, in consequence of the mor- bid state of the lung, a sufficient quantity of hydrogen is not expelled in the form of pul- monary aqueous vapour, this element is sepa- rated in excess from the blood in the paren- chyma of the liver, and there helps to form fatty matter. Mr. Bowman surmises, in a similar manner, that it arises from excess of carbon, (which it is the chief office of the liver to throw oft' from the system,) accumu- lating in consequence of imperfect respiration. But these conjectures are too exclusive in their bearing. Fatty liver occurs in non-phthisical subjects, whose respiration is naturally per- formed.§ Explanations of this class obviously fail to account for the unequal frequency of the fatty change in the phthisis of climates so closely similar as those of Paris and London ; and leave unaccounted for the greater ten- dency of phthisical Frenchwomen than Frenchmen to the pecuhar change. (2.) The Hver we have described is the *' fatty liver," per eminentiam. But undue deposition of fat forms a not unimportant feature in other morbid states of the gland. In cirrhosis, for instance, as particularly shown by Gluge||, Hallmann^, and Valentin**, accu- * Bright's Hosp. Rep. vol. i. p. 114. t De la Phthisie, p. 115, ed. 1. X Anat. Pathol, t. ii. p. 598. § This condition of the liver is comparatively very rare, as we have elsewhere observed, (Physical Diagnosis of Diseases of the Lungs, p. 215.) in the phthisical population of this country. Of the nu- merous tuberculous subjects we have opened within the last four years, (1845,) not one presented this morbid state to any marked amount. II Op. cit. ^ De cirrhosi hepatis. Berol. 1839. ** Repertorium, 1840. mulation of fat, either free or in vesicles, is as perceptible a character of the disease, as obli- teration of the ultimate bile-radicles and blood- vessels and atrophy of the lobular structure. But we do not believe, with Oluge, either that this fat-deposition is the solitary element of the diseased state in cirrhosis; or that the "fatty" state of the liver already described (1) is the first stage of cirrhosis. On the other hand there can be no question that the^true history of this common disease is, in respect of its fatty element at least, yet undetermined. (3.) There exists a third form of fatty condi- tion of liver, of which we have as yet but little experience, but which may not be passed over in silence. We have now some three or four times found minute crystals of choles- terin among the hepatic cells, (gathered toge- ther in sufficient quantity to render the nuclei of these obscure,) in portions of the gland, of pale fawn tint, flaccid, fragile, and rather greasy in look and feel. In one of these cases the gall- bladder was greatly distended with deep- coloured but quite fluid bile. (b.) Pancreas. — The proper texture of this organ is sometimes infiltrated with fat, in such manner as to give it the aspect of being com- posed of that substance*, — a condition per- fectly distinct from that of mere accumulation of fat betw^een its lobules. (c.) Mamma. — The acini of the mamma are said to be found by Dupuytren similarly affected ; the observation, we think, requires repetition; certain it is, at least, that in fatty hypertrophy of the organ the acini continue distinguishable. {d.) Kidney. — The kidney is subject to dif- ferent species of fatty change, which have been confounded by writers under the general title of " fatty degeneration or transformation." First: in certain cases of atrophy the renal textures dependent on cyst-formation, or on chronic pyelitis (either of calculous or simple inflammatory origin), abundant accumulation of fat takes place in the cellular tissue sur- rounding the kidney and underneath the cap- sule, and encroaches on its proper substance. Secondly: unnatural development of fat may take place amid the tissue of the kidney in connection with similar atrophy, sometimes perhaps as the cause, more frequently as the effect of this morbid change. Thirdly : the kidney, in very rare instances, acquires the colour and many of the properties of " fatty liver," greasing paper, &c. In a remarkable case recorded by M. Pascal f, the quantity of oil present was so considerable that it exuded from the organ under pressure, almost as from a sponge. No particular symptoms ^/7;/;cfify to have occurred in connection with this state ; but its symptoms and minute anatomy both require investigation. Fourthly: M. Gluge J, some years since, taught that one variety of alteration, found in the kidneys of persons cut off" with the symptoms of Bright's disease, w as * Lobstein, Anat. Path. pi. ix. fig. 1. t Journal Hebdomad. 2e serie, t. xii. p. 347. 1833. X Op. cit. Zweites Heft, S. 130. 1841. 9G PRODUCTS, ADVENTITIOUS. characterized by the deposition of fat-globules in the cortical substance. Of this alteration he recognises three degrees or stages. In the first, deposition of free fat-globules occurs in the cortical substance, unattended with obvious change in the tubuli or bloodvessels. In the second stage, deposition of yellowish altered fat-globules occurs within the tubuli of the cortical substance; the bloodvessels continue unaffected. In the third stage, deposition of peculiar altered fat-corpuscles takes place in rows in the site of the cortical tubuli; these tubuli being themselves destroyed in the same manner as the biliary ducts in the most ad- vanced stage of cirrhosis of the liver. More recently Dr. Johnson* has given a character of precision to our knowledge of the relation- ship of fat-deposit to the morbid changes in Bright's disease. He finds : 1. that the epi- thelial cells of the healthy kidney contain oil to a variable amount ; 2. that an excessive increase of this fat constitutes, primarily and essentially, Bright's disease ; 3. that the pres- sure of this fat causes, by a simple mechanical process, the presence of blood and albumen in the urine, and atrophy of the kidney. We are here simply engaged in considering the fact of fat deposition in the kidney, anil cannot digress into a discussion on the anatomy of Bright's disease. But we must venture to add that careful observation has shown and conti- nues to show us, that the compound state, known as Bright's disease, (renal alteration, al- buminuria, and dropsy, with the well-known train of secondary morbid conditions,) may exist without any undue deposit of fat in the kidney in any known form or condition. (e.) Testicle. — The testis is liable to fatty destruction, the fat accumulating in the oil-globule form without and within the tubules. (/.) Limgs. — Of fatty accumulation in the lungs little is known. We have never seen any condition cognizable by the naked eye, referrible to such alteration of structure ; and have not, even with the microscope, discovered accumulated fat in tubercular lungs, except amid the tuberculous matter itself. Under these circumstances we have regarded the fat as appertaining rather to the tubercle per than to the diseased lung ; nevertheless it has ap- peared to us that fat is associated in larger proportion with tubercle of the lung than with that of other organs. M. N. Guillot has recently informed the French Institute f that, while the sum of fatty matters contained in the foetal lungs varies from 10 to 18 per cent., it falls "to 6 per cent, on the establishment of respiration. He further conceives he has ascertained that in all affections attended with temporary or perma- nent suppression of respiration in a greater or less extent of lung, the ratio of fat increases in the impermeable tissue. The natural ratio of fat to tissue being seldom more than as 10 : 100, it may change to even oO : 100. * Med. Chir. Transactions, vol. xxix. p. 1. 184C. ■f- Comptes Eendus, Jiiillet, 1847. Had the author made these deductions from the examination of phthisical lungs onl}-, the fatty elements of tubercle might have been supposed to account for the excess of fat in the impermeable tissue ; but he affirms that in pneumonia the same phenomenon occurs. (g.) Arteries a7icl cardiac valves. — Of these we have already spoken (p. 87). {h.) Muscles. (1.) Volinitary. — In cases of continued inaction the muscles become in- filtrated with fat ; a fact readily ascertainable in those of paralyzed and of rachitic limbs. In old people the muscles of the calf of the leg and the sacro-lumbalis and longissimus dorsi frequently undergo this transformation. It is almost constantly observed in the muscles sur- rounding joints which are the seats of unre- duced dislocation ; and rnay be seen to ac- company the atrophy produced by anchylosis or other causes, and in the case of old ulcers which have for a length of time interfered with motion. In scurvy the muscles sometimes undergo a similar change. In a portion of muscle, appearing to the naked eye totally converted into fat, and weighing 13 drachms, H drachms were com- posed of muscle, 4 grains of gelatin, all the rest of fat.* The fact, thus chemically shown, that even in the most apparently perfect cases of disappearance of muscular substance, some of this remains, is fully demonstrable with the microscope also. Between and upon the muscular fibres and within the sarcolemma ap- pear fat cells and free oil globules. Gluge has pointed out the existence of saline crystals in rachitic fatty muscles. (2.) Involuntary. — Fatty destruction of the heart's substance may coexist or not with de- position of fat underneath the pericardium ; and, as Bizotf has shown, has no connection with superabundance of subcutaneous fat : in- deed this is true of the entire class of fatty changes, of which we are now speaking. The deposition of fat is most common on the right side of the organ, in the ventricle much more than the auricle. In these cases there is but a superfluity of natural fat, which encroaches on, and renders soft and atrophous, the proper muscular tex- ture. But there are certain forms of fatty change in which the muscular element itself is the seat of the primary disease, where a mottled dull yellowish aspect of certain portions of the organ is found to depend on accumulation of oil-globules within the sar- colemma. (/.) Tendon. — Deposition of fat occurs within the sheath, and amid the primitive fibres of the tendons of |:)aralyzed limbs. (/i-.) Nerves. — The same statement applies to the nerves of such lin)bs. In cases of atro- phy of the o[)tic nerve, fat accumulates within the neurilemma. (/.) Bones. — The bones become infiltrated * Cruveilhier, Essai sur I'Anat. Pathol, t. i. p. 18G. 181G. f Mem. de la Soc. Med. d'Observatiou, t. i. p. 353. PRODUCTS, ADVENTITIOUS. 97 with fat in a peculiar form of atrophy * of their proper texture, which is often attended with fracture. The latter circumstance distinguishes such cases from those of ordinary osteoma- lacia, wherein (in addition to other characters not belonging to the present head, as, for in- stance, disappearance of their gelatin-element, Miiller,) accumulation of free oil appears as an important character. (ni.) Adventitious Products. — Numerous adventitious products contain fat within their proper substance. Thus fat is a very frequent constituent of urinary calculi, and of various concretions, — for instance, the arterial species. In deposits, (as the typhous, tuberculous, and purulent,) it occurs occasionally in great abun- dance in the granule and oil-globule forms ; and it forms a constituent of no mean impor- tance (though an accidental one) of various growths. Thus in fibroma and osteoma the total absence of fat is unusual ; and in cancer fatty matter occurs with such constancy as almost to take rank with its essential elements. (B.) Fattt/ matters excreted in the semi-Jliiid or fluid state. — («.) Fat does not exist natu- rally in appreciable quantity in the urine ; in certain states of disease, however, oily matter is discharged in some quantities with the fluid. Simon and others have discovered fat in the urine of persons labouring under phthisis and tabes mesenterica ; and it is commonly said to be of most frequent occurrence in diseases at- tended with rapid emaciation. We have our- selves in vain sought for it in numerous cases of phthisis at all stages, and consequently re- gard its presence as by no means constant. Dr. EUiotson relates the case of a female suf- fering from biliary calculi who passed about the third of an ounce of oil daily with her urine f : such cases are, however, not to be regarded without suspicion. Fat occurs, oc- casionally at least, in considerable proportion in the urine of females affected with puerperal fever. J: Heller $ found the same principle in three cases of herpes zoster. Fat also exists, * The frequent association of atrophy with fat- deposition in various organs (Carswell, Gluge) is as curious as it is positively established; but the mode of connection of the two phenomena has not been fully ascertained, and is probably not con- stantly uniform. It would appear rational to sup- pose that the fat-production acts most commonly as the cause (mechanically) of the atrophy with which it is found ; but (to go no farther) in certain atro- phies of the kidney, the latter is, if not the cause, certainly the occasion of the former. It is a notable fact that in the organ which imdergoes the process of senile atrophy to the highest amount — namely, the lung — coexistent fat is not found ; at least, we have sought for it unsuccessftdly with the micro- scope ; it is true that M. Guillot's mode of inves- tigation might point out fat that had othen\ise eluded detection. Be this as it may, however, the same difficidty in determining the relationship of atrophy and other coexistent morbid changes (as, for instance, of serum-accumulation in atrophy of the convolutions of the brain in certain insane per- sons) is met with, as in the case of fat-deposition. t Med. Chir. Trans, vol. xviii. t Bouchardat, Joum. des Connaiss. M^dicales, Aout, 1843. § Simon's Chemistry, vol. ii. p. 320. VOL. IV. associated with albumen, in some cases of Bright's disease, in saccharine diabetes, and in the so-called chylous urine : and tbere are three cases on record (by Canubio, Alibert, and Graves) in which the fluid was actually milky, containing fat and casein. (/>».) The fieces sometimes contain oily and tallowy-looking matters in large quantities. The circumstances under which intestinal dis- charge of this kind occurs, are not by any means fully understood. Peculiar functional derangements of the digestive process are suf- ficient, independently of organic disease, to produce discharge of the kind, whether per anum or through the mouth.* The faeces in diabetes mellitus are remarkable for their large proportion of fat. Dr. Percy found this prin- ciple amount to 16.16 per cent, of the dried faeces in a case where food of all kinds was taken.f May the alleged fact that grape- sugar is converted into butyric acid by bile, be considered to explain (or at least to illus- trate) the occurrence of fat in these faeces ? Some of it is probably derived from non- digested food. (r.) The saliva occasionally contains " ad- ventitious fatty matter and fatty acid," accord- ing to Dr.Wright % ; he found so much as 3.9 of these principles in 1000 parts of one variety of morbid saliva. {d.) Tlie sweat is said to contain fat in the colliquative hectic state ; but we know of no analysis satisfactorily proving the point. § (C.) Encysted fats. — Fatty matters of dif- ferent kinds occur in cysts. The chief varieties of these are atheroma (from aOijpa, pnltis) ; meliceris (from mel, honey, and cera, wax) ; and steatovia (from artap, fat) ; so called re- spectively from their pultaceous, honey-like, and suety appearance. The most common seats of atheromatous and meliceric cysts are the scalp and eyelids the new matter some- times accumulates in the sebaceous follicles. One peculiarity of the fatty matter in meli- ceris and atheroma appears to be the absence of containing cells — the fat is free. Miiller hence presumes that the cyst is formed of the thickened walls of an original single fat-cell, — apparently an unnecessary hypothesis. Be- sides the fat, there is a granular matter of albuminous nature in these masses. Analyzed by Valentin j], the following was found to be the composition of this encysted fatty matter : — Cholesterin 0.352 Elain and oleate of soda 3.216 Stearin 0.222 Albumen and potass ; chloride \ j of sodium and lime J Coagulated albumen 5.923 Water , 88.715 Steatomatous matter is most commonly ac- cumulated in the ovaries, between the vagina * See the author's work on Cancer, p. 324. t Quoted in Simon, vol. ii. p. 378. t Loc. cit. I See Simon, op. cit. vol. ii. p. 110. II Repertorium, 1838, p. 307. H PRODUCTS, ADVENTITIOUS. 98 and rectum, and more rarely about the eyelids, scalp, neck, and prepuce. The matter itself is homogeneous, but differs in consistence in different parts of the cyst — it may be almost fluid in some. Dr. Lever* describes a cyst between the uterus and vagina which gave out a quantity of fluid matter, when punctured, that looked like " dripping" when cold. In ovarian cysts steatoma is frequently associated with hair. (D.) Cholcstericfats. — Plates of cholesterinf are frequently found in the fluid of hydrocele and of cysts of the thyroid gland. Rayer J found them in a cyst of the kidney, in a sub- ject whose aorta contained several small tu- mours a little above the bifurcation, seated under the lining membrane, and composed in great part of cholesteric scales. § In a female who lately died in our wards with obstructed bowels from stricture of the rectum, a large cyst lying behind the right psoas muscle con- tained cholesterin in atheromatous-looking patches on the inner surface of its wall : here it was undergoing calcification. Cholesterin has been found in scales among pus of an abscess near a carious tooth || , and of an abscess near an anchylosed joint-lf In such cases it disappears from the secreted matters before suppuration ceases. Cholesterin occurs occasionally in various morbid growths, — for example, in the different varieties of cancer. Closely allied to (if not sometimes identical with) cholesterin in chemical constitution, is a fatty product, for which the name of chole- steatoma has recently been proposed by Miiller. This substance occurs in the forms of (1) tiL- mours ; (2) granules ; (3) patches ; (4) scales. (]). Tumours composed of this material are commonly of the consistence of tallow ; firmer than the brain when found in that organ. They are not lobulated, but frequently mam- millated on the surface ; uneven, with a gene- ral tendency to roundness ; surrounded with a capsule of delicate fibrous structure ; varying in size from a walnut to the clenched fist and upwards. Of sixteen recorded cases the brain was the seat of the tumour in seven ; the bones in three ; the utero-rectal cellular tissue in two ; subcutaneous cysts in three ; a large cysto-sarcoma of the breast in one. The interior of the mass has a shining white and semi-transparent aspect, either generally or in some spots only, while in others the white colour is dull, Miiller found that the substance shrinks and becomes yellowish by desiccation. All who have observed it describe it as com- posed of delicate laminae, for the most part * Med. Chir. Trans, vol. xxiii. t Becquerel and Rodier affirm tliat the proportion of cliolesterin in the blood increases in persons of both sexes from the age of forty to fifty: hence, perhaps, the greater frequency of separation of this fat in old people. % ]Maladies des Reins, t. iii. p, 541. § See also Christison, Ed. Med. and Surg. Jom-n. vol. xxxii. p. 278. II Caventou, Journ. de Pharraacie, t. xi. p. 463. 1825. ^ Nasse, MttUer's Archiv, 1840, Ileft. iii. S. 2G7. arranged concentrically, and easily separated : it is completely extra-vascular. The laminae and the matter interposed be- tween them possess different structures, (a.) The laminai consist of superimposed strata of cells, rendered pentagonal, hexagonal, or polygonal, by lateral mutual pressure, resem- bling, except in size (they are only half as large, averaging a diameter of .00081 of an inch), the cells of sheep's fat {fig. 91) ; easily Pohiqonal cells of cholesteatoma magnified 290 times. (After Muller.) separated from each other, transparent and pale; possessing neither nucleus nor central granules, and admitted to be hollow, rather from the analogy of sheep's fat, than proved to be so by observation. The substance form- ing the cells is distinct in its nature from fat, as it is neither dissolved nor deprived of its laminated appearance by boiling alcohol. (/?>.) The inter-laminar matter consists of crystals tabular and lamellar. The tabular are in greatest abundance ; generally short, broad, and rectangular, but frequently narrow and riband-like, and probably composed of pure cholesterin (which appears under the micro- scope in the form of rhombic tables), as acids and alkalies do not affect them. The lamellar crystals look like aciculae of stearin from their being gathered into bundles ; but when deposited from their aethereal secre- tion they are distinctly lamellar, and pointed at both ends. (2.) Granules. — We agree with Miiller in believing that the pearly looking globules described by Cruveilhier in a cancerous growth of the testicle* were very probably composed of cholesteatomatous matter. (.3.) Patches. — Dupuytren observed patches of this substance on the surface of a urinary fistula ; Miiller a stratum of it covering a can- cerous ulcer of the mamma. (4.) Scales. — The fluid of hydrocele and of tumours of the thyroid gland frequently con- tains scales of a pearly looking matter, some- times collected abundantly at the most de- pendent part of the cavity. This matter, commonly believed to consist of cholesterin, is not always so composed. Dr. Bostockf found it essentially different from adipocere and from cholesterin, not soluble in water or in alcohol, but partially so in aether, and in- capable of saponification by potash. Miiller found the alcoholic or aethereal solution of the tuberiform variety yielded no oil on eva- poration, but a fine granular fat, probably stearin, with lanceolate lamellar crystals, * An. Path. livr. v. tab. i. fig. 2. t Med. Chir. Trans, vol. xv. p. 158. PRODUCTS, ADVENTITIOUS. 99 having convex edges converging to a point at either end, as before referred to. In the peculiar softening of the vitreous humour called sparkling synchisis, the spark- ling appearance at the bottom of the eye is said (Bouisson) to depend on the presence of molecules of cholesterin.* The development of masses of chole- steatoma takes place, independently of blood- vessels in its substance, by successive genera- tions of layers of cells, each layer being removed from the seat of its formation by that following, precisely after the model of epithelium. The cells being, as far as ob- servatidh has gone, unprovided with nuclei, and containing no sub-cells in their interior, cannot be considered capable of producing new cells ; the seat of true production there- fore, as long as the mass continues to enlarge, remains unchanged to the last. § III. Sugar. — In a peculiar state of the system, the essential nature of which is as yet enveloped in obscurity, starch-sugar (identical in all properties with glucose j) accumulates in sufficient quantity in the blood to be easily detected in that fluid by chemical analysis. The same substance impregnates the secre- tions and excretions, — the urine, the fseces, the perspiration J, the expectoration and (as is inferrible from certain experiments |j) the gastric juice. In this disease (known as saccharine dia- betes) the condition of the urine has aUvays clinically attracted the chief attention. Not only is the sugar most easily discoverable in the urine, but this fluid is otherwise strikingly altered in qualities : its specific gravity ranges from 1028 to 1055 while its amount varies from two or three to seventeen pounds in the course of twenty-four hours. The connection of albinninnria with diabetes is matter of dis- pute. Cotunnius** observed long since that albumen occasionally occurs in diabetic urine. Schonlein states, that the presence of sugar is preceded by that of albumen, the latter dis- appearing, while, with the advance of the disease, the former increases in quantity. Thenard and Dupuytren, observing coagu- lability of the urine occur in cases, where the fluid had been excessively abundant and sac- charine, regard albuminuria as of favourable augury. M. Rayerf-j- has frequently known the change (as might be expected) announce coming dropsy. Fat sometimes exists in suffi- cient quantity in diabetic urine to render it milky-looking. J J The once popular idea * Ranking's Retrospect, vol. vi. p. 286. t Thenard, Rayer, and Bouchardat formerly maintained that diabetic urine sometimes contains an Lasipid sugar, independently of, or in addition to, the sweet variety ; but later observations disprove the existence of'^anv such body as the insipid sugar. t Xasse, Rhein. Corr. Blatt. No. vi. 1842. I Francis, Lond. Med. Gaz. Feb. 12. 1847. li Those of !Mr. M'Gregor ; vide note, next col. ^ The specific gravity- is in exceedingly rare cases not raised much above the healthy staiidard; Dr. Prout once found it even below this (1015). ** De Ischiade Xervosa, p. 31. 1770. tt Mai. des Reins, t. i. p. 151. XX Rayer, in L'Expe'rience, 1. 1. p. 664. that sugar takes the place of nrea in the urine has been set aside by Mr. M'Gregor's investi- gations, which show that the daily discharge of urea may throughout not only equal, but exceed, the healthy average. Deficiency of urea (which sometimes occurs) can only be regarded as accidental. Various theories of the pathology of dia- betes have been started. Those of the or- ganic class (gastric, renal, &c.) have hitherto proved inadequate : the most accurate investi- gations have failed to establish any textural alteration antecedent in development to sugar-accumulation in the blood. Doctrines of the chemical class are in one point of view more entitled to consideration. Rollo originated these by ascribing the disease to mal-assimilation in the stomach — to decom- position of vegetable food into sugar through the influence of morbid gastric juice. Mr. M'Gregor's experiments proved the produc- tion of sugar in the stomach from amyla- ceous substances*, and thus gave the appear- ance of demonstration to RoUo's theory. Nor can more modern speculations be said to have done much el=e than to have shaped that theory to the principles of advancing chemistry. Of these speculations it appears well to notice two. In the first of these the argument runs as follows : — In the natural state of the digestive process sugar is not evolved from starchy mat- ters, the formation of that substance stopping at what may be called the dextrin stage : and further, the economy is doubly guarded against the passage of sugar, used as food, into the secretions : first, by a power on the part of the stomach of transforming sugar ; and secondly, by a similar power on the part of the blood. Now in diabetes, it is assumed, both these powers are lost : swallowed sugar is not con- verted ; and amylaceous matters are carried beyond the dextrin stage of transformation, and changed into sugar. But this doctrine of the chemistry of the disease appears to fall before the facts, that if much sugar be taken in a state of health, (as by persons indulging in punch to any amount,) the urine is distinctly found to contain sugar : nay, even under ordi- nary circumstances, sugar has been detected (Buchanan) in healthy blood soon after anieal. The second theory, to which we shall refer, may be deduced from the following document, kindly supplied to us at our request by our colleague Professor Graham. " The principal conclusions to which I have been led by a comparative examination of the * Feeding a diabetic patient ujwn beef, Mr. M'Gregor found sugar in the contents of the stomach vomited immediately after a meal, and concluded (a notion accepted by Berzelius as the basis of his own theory) that the protein-compounds had been converted into sugar. The true explanation of the fact seems to be, that in this disease the blood con- tains so much more sugar than natiu-al, that a cer- tain share is thrown out with the gastric juice, and is of course discoverable immediately among vomited food. It is matter of doubt with the best chemists, whether sugar can be evolved from the much more closely allied substance, fat. H 2 100 PRODUCTS, ADVENTITIOUS. ingesta and digesta of diabetic patients, con- tinued in two cases daily w ithout interruption for several months, and for a few days at a time in several orher cases, are as follows: — " The quantity of saccharine matter found in the urine never exceeded the sugar and starch in the food. On the other hand, the sugar and starch of the food were accounted for in the urine to within one-fourth or one-fifth of the ■whole quantity. As there was always sugar besides in the fasces in a sensible, although not considerable, quantity, it appeared to follow that sugar and substances convertible in the stomach into sugar, are, in diabetic patients, nearly if not entirely indigestible ; that is, they pass through the blood without being burned and thrown off in the form of carbonic acid and water, as they are in a healthy state. The idea of any portion of the saccharine matter found in the urine being formed from the pro- tein or azotized portion of the food was entirely excluded. " The proportion of sugar in the urine has a limit which it cannot exceed, but which varies within a small range in different patients, about 4i per cent, being the usual maximum. The volume of the urine comes, therefore, to be en- tirely governed by the quantity of saccharine matter in the food. " Although sugar escapes oxidation in the respiratory process of diabetic patients, alcohol is entirely consumed. On one occasion a dia- betic patient swallowed twelve ounces of abso- lute alcohol, contained in a quart of whisky, within twenty-four hours, without a trace of it appearing in his urine or other excretions. Gum arabic also, taken as food to the extent of five or six ounces a-day, did not cause an in- crease of sugar in the urine, and was probably, therefore, digested. Both alcohol and gum are, like sugar, pure aliments of res[)iration. " It is well known that in the air expired by man, the proportion between the volume of carbonic acid found and oxygen deficient is remarkably uniform, and indicates that an excess of oxygen, nearly constant in amount, is consumed above what is represented by the carbonic acid, due of course chiefly to the oxidation of hydrogen. An amylaceous diet, in which the only combustible element is carbon, tends to reduce this disproportion, while an animal diet increases it. 1 therefore espected to find a deficient proportion of carbonic acid in the expired air of a diabetic patient confined to an animal diet ; but such was not the case ; the proportion proved to be perfectly normal. This implies a considerable waste of azotized food, — that even the protein-compounds are only partially digested in the system of a diabetic patient. The assimilating power ap- pears, indeed, to be generally deficient." According to Mr. Graham, then, the disease is to be understood thus : — In consequence of deficient oxidation of sugar in the respiration- process, that substance (which in the natural state of things is burned off as quickly almost as it mixes with the circulating fluid) accumu- lates to a greater or less extent in the blood, and its elimination from this fluid is partially effected through the secretions, especially the urine. This is a most plausible and clear view of the chemical mechanism of sugar-disease ; but a quid ignolum — the cause of the deficient oxidizing power — remains in the back-ground, mysterious and impenetrable. Class II. — Plastic Products. This class includes all products possessed of organized arrangement, whether their structure be of a rudimentary or advanced kind; we shall distinguish them by the term Formations. Formations are themselves separable into two very distinct sub-classes; — the one m which the formation depends for continued existence upon the immediate and direct access of nutri- tious matter from the blood of the parent or- ganism {Blastemal Formations) ; the other in which the vitality of the formation is not dependent upon such direct access {Germ- Formations or Parasites). While the products referrible to these two sub-classes differ in their structural characters, in their properties, in their vhal actions, and in their influence on the organism containing them, they are no less distinct in their mode of origin. Those belonging to the one sub-class originate in a structureless fluid or blastema; those belonging to the other spring from a germ. And the distinctive attributes of the two sub-classes may in the most concise manner be put thus : — Sub-Class I. — Dependent existence ; origin from a blastema. Sub-Class II. — Independent existence ; origin from a germ. sub-class I. — blastemal formatioxs. The structureless fluid just referred to is termed blastema (from ^KacrToc, a germ) in consequence of its being the germinal material from which certain formations are evolved ; and likewise cytoblastema {kvtos, a cell), be- cause an essential process in that evolution is the generation of cells. The source of this material, as of the forma- tive material of the natural elements of the organism is none other than the circulating fluid — the blood.* But there are three possible forms in which the blood may be supposed to furnish the germinal material in question. First, the blood in substance may itself constitute blastema ; secondly, some of the elements of the blood, unaltered in properties, may con- stitute blastema ; and, thirdly, some of those elements altered in properties may constitute blastema. Now, analogy is opposed to the admission of the flrst of these possible cases : there is no instance of a natural structure being evolved from the blood as a whole. But arguments founded on analogy are valueless, if at variance with the results of direct and satisfactory observation. As matter of experience, then, does blood in substance, unaltered in apparent physical properties, and either retained within * Of the chyle and lymph, as suppliers of blaste- mal elements, nothing is kno^vn practically. PRODUCTS, ADVENTITIOUS. 101 or extravasated from the vessels, ever act as a blastema for cell-evolution ? John Hunter, as is well known, held that extravasated blood was capable of organization (by which term he meant vascularization) ; but his statements do not by any means prove that the masses, as- sumed by him to be simple coagula, were not in point of fact more or less extensively mixed with coagulable lymph, or inflammation-exuda- tion. Others have, however, endeavoured to give support and greater precision to the views of Hunter. Mr. Dairy m pie*, some time since examining a coagulum (injected by Mr. Busk) seated between the tibia and its periosteum in a scorbutic patient, found its substance per- meated by vessels, which he judged to be of new formation. The form, mode of arrange- ment, and general characters of these vessels, (as we have ourselves seen,) seem to justify the idea that they are really new formations ; but no proof that exudation-blastema may not have been present amid the extravasated blood is adduced by their describer. More recently, Mr. Dalrymplef, not content with ascertaining the fact of vascularization of scorbutic coagula, has succeeded in tracing the progress of cell- development in the substance of such coagula. But if vascularization existed, the humbler grade of organization, signified by cell-production, was to be expected ; and the new observations of Mr. Dalrymple do not remove the objection which in this point of view may be made to the old. Still these observations show very satis- factorily that the presence of blood in sub- stance will not prevent the occurrence of cell- evolution and of vascularization, when the other conditions of its accomplishment exist. J In describing H-Ematomata, further on, we shall have occasion to return to this question ; the reader may refer also to our observations on Softened Fibrin in the article on Pus. Secondly^ the blood-elements comprised un- der the title of liquor sanguinis, sUg'htli/ modi- fied in their relations of quantity and in their vital tendencies, are capable of constituting morbid blastema. By changes, such as these, is educed from the blood the fluid called coagulable lymph, the nature of which v.ill hereafter be more fully considered. Thirdly ^ certain elements of the blood, more or less deepli/ modified in essential properties, form the most common species of blastema. And what is the nature of the modification referred to ? Is it physical, chemical, or simply potential ? («.) As far as observation goes, the modifi- cation is not of i^hysical character. Formations the most various (just as natural textures the most various) spring from blastemata having the same physical qualities. (6.) Of the chemical constitution of blaste- mata at the moment of production, nothing is known from actual experiment ; but that it is (setting aside its saline ingredients) albumino- fibrinous maybe admitted as matter of inference from the source and mode of its production. * Med. Chir. Trans, vol. xxiii. p. 205. 1840. t Med. Chir, Trans, vol. xxvii. p. 70. 1844. X See the author's work on Cancer, p. 51. Scarcely, however, have these blastemata be- come the seat of cell-evolution than, as is fully established, their chemical composition varies very materially ; while the resulting mass is in some instances essentially composed of albu- mino-fibrinous elements, in others it is of fatty nature ; in yet others it yields gelatin. The question then arises whether the chemical dif- ference detected in any two given morbid for- mations has existed in their blastemal fluid ab origine, or been eflfected in connection with the process of cell-germination. In the ab- sence of direct information on the point, it is natural to apply for its elucidation to the phe- nomena of healthy nutrition. Now, in the evolution of the Jiatiirnl tissues^ compounds of various chemical constitutions spring into ex- istence in close juxtaposition from the same blastemal fluid. And this diversity of che- mical combination is certainly connected in some way or other with the presence of cells : for one of these vesicles (while the walls of all are, as far as is known, of prottin-basis) may be shown to have fat for its conteiitSy another pigment, another a protein-compound, &c. ; whereas, previously to the occurrence of cell-evolution, no such chemical distinctions could be established within the blastema. Chemical changes and cell-evolution are then connected ; but in what manner ? Conceiv- ably in one or other of two wa} s : the development of cells may be (])a mere coin- cidence with the generation of new chemical compounds, or (2) it may be its cause. 1. That it is a mere coincidence; in other words, that the cells are passive, and the blas- tema itself alone active in the chemical changes, cannot be admitted ; all analogy is against it. Thus the importance of yeast-cells in the phe- nomena of fermentation is too obvious to be denied even by those, who refuse to accept the view of Schwann that those phenomena cannot occur at all in fermentable matters, unless through the influence of cells. 2. Cell- action then must have some influence as the cause of the chemical changes, and may by possibility be their (a) sole or (;3) their partial cause. (a) Supposing the cells the sole agents, we must admit that their solid constituents (wall and nucleus) in virtue of an inherent faculty (the so-called metabolic force) form new compounds out of the homogeneous matter surrounding them, this matter being chemically passive in the changes occurring. This was Schwann's view, and he grounded it on the analogy of the alleged necessity for the presence of cells as a condition sinJ qua jion of fermentation in fermentable matters. But, as Henle has urged, the influence of cells is here exaggerated ; cases are not wanting in which organic matters undergo chemical change through the sole agencyof heat or acids, independently of the evolution of cells. And, it may be added, that in the progress of some fermentations, yeast-cells not only do not germinate, but actually disappear, as in the instance of a fermenting solution of pure sugar. (6) It would appear probable, then, H 3 102 PRODUCTS, ADVENTITIOUS. for this reason that chemical change is in some measure worked out by (and, infer- entially, that chemical differences exist nh origine in) blastemata themselves ; but, even thus, the cells must have an influence second- ary only in time, not in importance. Like all membranes placed between fluids of different nature (the surrounding fluid and that con- tained within them), the cell-wall must be the seat of endosmosis and exosmosis, and the chemical result must be regulated, on the part of the cell, not only by the nature of mem- brane or cell-wall to be permeated, but by the nature of the fluid contents of the cell. (c.) That the potential qualities of different blastemata differ is perfectly obvious ; exist- ences (such as cancer, pus, tubercle) must be formed from materials endowed with different vital tendencies. Concerning the nature and essence of this potential difference nothing is known with certainty. As respects the pro- cess by which its own special character is impressed on each blastema, and the locality in which that process is accomplished, three cases are possible : either the special character is given while the elements of the blastema are still circulating with the blood ; or while those elements are undergoing filtration through the walls of the vessels ; or at both these periods. Now, though it is probable that the filtration process exercises some in- fluence of the kind under consideration, yet it is next to certain that the main influence is exercised on the blastemal elements within the vessels by the constitutional state of the indi- vidual,— that upon this constitutional state, and not upon any local process whatsoever, mainly depends the issue of a blastema, whether it shall be evolved, for instance, into cancer or fibrous tumour, pigment-cells or pus, fat or enchondroma. The blood being the source from which blastema is derived, there are three distinct situations in which it may, n priori, be sup- posed to undergo evolution into structure : (rt.) within the vessels : {h.) in the substance of the vascular walls : (c.) outside the vessels. Whether evolution does occur in ah these situations requu'es to be examined into. (ff.) Certain adventitious formations are unquestionably found occasionally in the in- terior of the veins, and their presence can only be accounted for in one of two ways, either as the result of the absorption and subsequent germination of certain elements of growths pre-existing elsewhere, or of primary evolution of blastema which had never escaped from the vessels. There can be httle doubt that in the great majority of cases intra- venous Forma- tions are produced by evolution of absorbed elements ; but it appears probable that they may sometimes spring from retained or 7^072- exnded blastemal elements. It is true, the embryonic production of a fragment of natural tissue within the vessels is an anomaly of nutrition of which no example has, as far as we know, been witnessed ; analogy is conse- quently opposed to the admission of a germi- nating force in non-exuded blastema. It is likewise true that, in respect of the simplest form of blastema (the inflammatory) escape from the vessels appears essential to evolu- tion as a general fact ; nevertheless, it is to be remembered, inflammation-products are evolved within the vessels in cases of arteritis and phlebitis, and in the healthy state epithe- lium is constantly being produced on the internal vascular surfaces. Hence the possi- bility of retained blastema germinating within the vessels must be, at least provisionally, conceded ; and such germination may be imagined most readily to occur where pecu- litu-ities of texture interfere (as in structures of the erectile class) with the process of exudation.* {b.) Nodules of adventitious structure have sometimes been met with in the actual sub- stance of the parietes of the veins. The locali- zation of these nodules becomes intelligible on the supposition either that blastema, furnished by the blood circulating in their interior, has germinated during the process of filtration through the vascular coats ; or that the blas- tema was originally supplied by the vasa vaso- rum. The fact that the nodules in question have been principally met with in veins of a certain size (where exudation does not habitu- ally occur) makes it probable that, in some cases at least, the vasa vasomm are the source of supply. (c.) But both localities, so far considered, are rare, though possible, seats of germination ; hence it follows directly that the common site of the phenomenon must be outside the vessels, and indirectly that the process of filtration through those tubes is commonly a necessary element in the generation of a blas- tema apt for evolution. Hence it is that exudation Jiuid has been employed as a sy- nonym of blastema in general. Now the possible positions outside the vessels are : — the intervascular interstices of the various tissues and organs ; the free (or sub-epithe- lial) surfaces, mucous, serous, and cutaneous ; the surface (and, mediately, by imbibition, the substance) of the extra-vascular tissues ; and, lastly, adventitious surfaces, produced by wounds and other agencies. Now observa- tion (while it has decided that germination does actually occur in all of them) has proved the first-named of these situations to be by far the most common seat of the pheno- menon. , In those cases, unfortunately restricted in number, in which observation has succeeded in establishing the chai'acters of blastema (as in the instances of induration-blastema and pus-blastema) this fluid has been found homo- geneous, almost perfectly transparent, slightly * It is clear that what has been spoken of by writers as the " conversion of blood " into the sub- stance of certain Adventitious Formations can be nothing more than an appearance proiluced by the evolution of primary- blastema or of absorbed blas- temal elements in "the interstices of a coagulimi: the idea of an actual change of either blood corpuscle into the cell of an Adventitious Formation is wholly inadmissible. PRODUCTS, ADVENTITIOUS. 103 viscid, and free from solid particles of any kind. And the evolution of all kinds of blas- tema proceeds in the same manner, as far as hitherto ascertained, until the formation of cells is effected. The successive steps may in general terms be stated to be increase of viscidity, formation of granules, of nuclei, and of cells.* And these various steps cannot be accomplished except in blastema in contact with living animal structure, — a blastema loses its potentiality either by the death of the textures amid which it is evolved, or by its removal from among them. We place no confidence in the experiments upon which a statement of certain exceptions to this law has been founded, f No matter what be the ultimate destiny of the blastema, the process of its evolution is conducted, then, on the same principle ; but the development of cells sets a limit to this identity of process. The vital qualities of the cells differ, and affect the function and end of these, in three principal modes ; and, accord- ing as each of these prevails in any given blastema, will the product generated (solid or semi-soHd) present peculiar characters. These three modes of cell may be described as fol- lows. First, the cells once developed may be alto- gether inapt for life, incapable either of under- going such changes in physical, chemical, and vital constitution as shall qualify them for sus- taining a permanent existence, or of generating the elements of new cells previous to their own destruction. They are consequently acted upon physically and chemically by the sur- rounding materials : they are either dissolved by the fluid with which they are associated ; or, disintegrated and broken down into non- productive granular matter, Ihey lose all trace of the attributes of organization. Cells of this kind may be termed evanescent and retro- grading. Secondly/, the cells may be deficient in the faculty of permanency requisite for the forma- tion of tissue ; while, on the other hand, they possess the power of generating the elements of new cells (or of causing indirectly the generation of those elements) previously to their own disappearance, — cells endowed in turn with a similar generative force. These cells consequently present the characters of the formative stages of evolution, never those of perfectly evolved structure. To this kind of cells the title non-permanent and vegetative may be applied. Thirdly^ the cells may possess an inherent force, qualifying them to pass through the necessary steps towards the formation of structure more or less closely resembling the natural tissues, and in this evolved condition they are destined permanently to remain. These cells appear likewise to be destitute of * The production of fibres without the interven- tion of a cell-stage (an exceptional phenomenon, if the entire system be taken in view) will find its place elsewhere. t Helbert, de exanthematibus arte factis. Gott. 1844. the power either of generating or of indirectly causing the generation of the elements of new cells similar to themselves ; they may there- foi'e be termed permanent and non-vegetative cells. From cells of one or other of these three kinds all blastemal formations are produced. Formations produced from the evanescent cell are non-stromal, and may be termed deposits; those from the vegetative cell are stroma/, and may be termed growths ; those from the permanent cell nve stromal, and may be termed pseudo-tissues. Order I. — Deposits. Deposits are deficient in the characters of texture ; they possess neither permanent fibre, nor definite arrangement of parts, se|)ta, nor loculi ; and are insusceptible of vascularization. They tend to produce eliininatory action and ulceration in the seats they occupy ; and are prone to appear, mainly through the influence of so-called " diathesis," in several parts of the frame simultaneously or consecutively. The substance of all deposits is per se non-inocu- lable ; we say all, because, though the point has not been, to our knowledge, experimentally tested in regard of the typhous and diphtheritic species, there can be little doubt that the proposition applies to them as to the others. But certain varieties of one genus of deposit (pus) are, on the contrary, readily inoculable through the agency of certain associated principles called viruses (see Pus). In such cases, be it observed, the propagation of the disease in no wise depends on the cell of the fluid. In the order Deposits (constituting transi- tion products from the non-plastic protein- precipitates to formations of higher attributes) we place the following genera : typhous, tuber- culous, purulent, melanic^ and diphtheritic pro- ducts. § I. TYPHOUS DEPOSll^^ ; \ In the form of continued fever ana^ontcally characterized by alteration-^£-sti:^^r^n the glandular textures of the^-Sj:£iaS^-*flfestine, a peculiar substance of new formation (as first accurately described by M. Louis*) is dis- covered in the cellular membrane between the mucous and muscular coats of the patches of agminated glands of Peyer. The propor- tion of cases of continued fever of intestinal type in which this deposit occurs, has been differently estimated from less than one third of the cases to nearly the entire number. We have found this matter homogeneous in aspect, of pinkish or yellowish hue (the former acci- dental), and from a sixth to a quarter of an inch thick ; we have always seen it more or less firm and tenacious, and never succeeded in catching it in its earlier stage of fluid blastema. Examined under the microscope by Bcihmf it appeared utterly destitute of * Eoederer and "Wagler (De morbo mucoso, p. 332.) first noticed this substance thus: " ue semel tamen elevatos [folliculos coagmentatos] et materia mucosa obscure cinerea repertos vidimus." t Brit, and For. Med. Rev. vol. i. p. 524. H 4 104 PRODUCTS, ADVENTITIOUS. structure, and so it commonly is. But in some instances, in addition to granular matter lying in a structureless substance, renuiants of cells may be detected, and, more rarely still, nucleated cells of unbroken outline, some larger, others smaller than the red blood- corpuscle. Epithelium cells are often acci- dentally present, as also oil globules. That the main clement of this material is of protein-basis may be inferred from its general properties. Buzzorini* gives its composition from direct analysis as follows, — fibrin, phos- phate of lime, lactate and hydrochlorate of soda, and traces of other salts of the blood. Under the microscope acetic acid renders the basis more or less transparent : its effect on the cells seems to vary. We have seen matter of similar character in the mesenteric glands ; and we cannot afhrm that the intestine and these glands are its sole seats, not having looked for it in other parts of the body of typhoid patients. § 2. TUBERCULOUS DEPOSIT, OR TUBERCLE. Tubercle, when in that condition that its properties are most clearly marked, and when at that period of its development that no dissentient opinions are held as to its nature, possesses the following characters. It is an opaque substance of yellowish colour; suffi- ciently firm yet friable, of little tenacity, and resembhng cheese very nearly in point of consistence ; inelastic ; without particular smell ; accumulated in small masses varying in size from a pin's head to a hen's egg, of homogeneous aspect all over their divided surface ; exhibiting no vessels ; insoluble in water, and if mixed therewith quickly subsid- ing to the bottom. And these are the pro- perties of a material which, in respect of its physiology, is characterized by its tendency to become soft after it has existed for a variable period in the condition of firmness, and to induce various changes in the natural textures with which it is connected, changes eventually effecting its own complete disin- tegration and elimination. Nothing can be more true than that tubercle is homogeneous : but this may or may not be true of a tubercle. A tubercle of the brain is perfectly so ; each particle is the counterpart of all others composing it, and for the simple reason that the natural structure, wherein the new matter has found a nidus, has been pushed aside in proportion as that matter has accu- mulated. A tubercle of the lung, again, may also upon rough inspection appear homoge- neous ; but if closel}' scrutinized with the naked eye, or, better, with a lens, it will be found that the section of the little body is marked by lines of a different tint and aspect from its general substance. This arises from the enclosure of some of the tissue of the organ by the accumulating tuberculous sub- stance. Tubercle may be deposited in isolated masses, or, it is said, be infiltrated through the stroma of the various tissues. (1.) When * Der TA-phu5, 1836, S. 87. occurring in masses it is usually of tuberiform shape, and the mass has sprung either from a single centre of formation, or from the con- crescence of several smaller tubercles formed in the close vicinity of each other. It has long been a subject of dispute whether tube- riform tubercle occurs in the encysted form. Laennec held the af&rmative ; and M. Louis follows on the same side. Dr. Carswell " feels perfectly satisfied that the term en- cysted, whether applied to pulmonary tubercle or to tubercle in any other organ, is almost always incorrect. In the lungs encysted tu- bercle is a deception, the distended walls of the air-cells having in all probability, in almost every case, been taken tor cysts. In like manner the dilated bulbous extremities of the biliary system have been described as cysts of the liver containing tuberculous matter."* The e^•idence furnished by Laennec and M. Louis is defective ; the latter observer never saw the presumed appearance in the lung but once, and no description is recorded from which the accu- racy of the explanation offered may be ascer- tained.t On the other hand. Dr. Carsweli's objection turns altogether upon his special notions concerning the ahnost limitation of tubercle to the mucous surfaces. We have ourselves never seen encysted tubercle in any structure of the body, if by the term be under- stood tubercle contained within a cyst, which has acted as its formative organ. But we have seen in very rare instances in the lung, and, comparatively speaking, somewhat more fre- quently in bore, tuberculous matter surrounded by a more or less complete membrane, strongly assimilable in properties to the pyogenic mem- brane of abscesses, and, hke it, obviously formed consecutively to some at least of the matter it invested. Such we beheve to be the key to the comprehension of " encysted tu- bercle," especially taken in conjunction with the fact that true abscesses in the lung have not unfrequently been mistaken for tuberculous accumulations. To the class of secondary cysts is also to be referred that species of membranous investment occasionally formed round tuberculous matter w hile undergoing a process of inspissation. The tubenfonn shape is so common in tu- berculous masses that its cause has been made matter of inquiry. By some persons pre- sumed to depend on a moulding faculty in- trinsic in the tuberculous substance (an obvi- ously absurd notion), it has been referred by Schroeder van der Kolk and Dr. Carswell to the influence of the surrounding parts. The latter observer well shows that, in point of fact, this shape is less common than has been maintained, and scarcely occurs except in the brain and cellular membrane, and under cer- tain circumstances in the lung. Stratiform deposition is that occurring on serous sur- faces in layers ; ramijbrm, that observed in the bronchi and biHary system. * Illustrations of the Elementary Forms of Dis- ease, Fascic. Tubercle. t Louis on Phthisis, Walshe's Transl. Reprint, p. 426. PlIODUCTS, ADVENTITIOUS. 105 (2.) Infiltrated tubercle has been described principally in the lung, and is here said to ex- hibit two kinds of appearance ; {a) the gret/, and (b) the geJatinifurm. (a) There are oc- casionally found in the lungs irregular masses of variable and, it may be, considerable size (five inches in diameter even) of greyish semi- transparent aspect, homogeneous, shining, and without distinct structure ; such appearances are generally seen to^vards the apex of the organ, and may exist in very rare cases inde- pendently of any acknowledged form of tuber- culous deposit ; slices of texture thus affected sink in water, are moist on the surface, dense, and compact. In the midst of such masses it is sufficiently usual to discover a number of small specks of yellow opaque tuberculous matter; these increase in number and size, and thereby gradually cause the disappear- ance of the grey matter. Now it is admitted on all hands that the characters of this alleged tuberculous infiltration are extremely like those of chronic pneumonia; and in our mind it is extremely doubtful whether the morbid state be anything more than a particular form of that inflammation. M. Louis draws at- tention to the following points as distinctive of chronic pneumonic induration : — 1. Instead of being transparent, the affected tissue is opaque ; 2. instead of being homogeneous, it is traversed by thick white septa ; 3. the in- durated parts are mere compact than in the presumed tuberculous infiltration. But in ac- knowledged chronic pneumonia all these cha- racters are subject to a great variation in amount; and the formation of yellow tu- bercle proves nothing in either direction, as there is no reason why such formation should not occur in a tissue infiltrated with indu- ration-matter, (h) Of the gelatiniform tuber- culous infiltration of Laennec, it is sufficient to say that no doubt can be entertained as to the fact of his having described, under this name, infiltration of common exudation matter with excess of serosity, sanguineous or not. Tubercle does, however, occur in the endosteal texture of bone in the infiltrated form. The microscopical constitution of yellow tubercle may be described as follows, at least according to the observations we have our- selves made. (1.) Granular substance exists in abundance in tuberculous matter ; large masses of soft consistence sometimes consist almost solely of it ; and, as the process of softening advances, it abounds likewise; when of well-defined characters and abundant, it constitutes a very distinctive element of tu- bercle. The granules are dark, of yellowish brown tint, heaped up in masses, varying in size from about l-4th or l-5th of that of the red blood corpuscle (say i ^ioo oi' t^ooo of ^'^ inch) to the merest points. Some of them, undissolved by acids, alkalies, or ether, are of modified protein-basis ; others, soluble in hot ether, are of fatty nature : the latter are sometimes, though rarely, absent altogether. (2.) Cells. — Cells, though probably always ex- istent in tubercle at some stage ofits develop- ment, are not always to be found, or to be found in very minute proportion only, in specimens examined. In some cases they apparently con- stitute the entire tuberculous mass. We have found them sometimes of circular form, and rather flattish ; sometimes irregular in shape and with rounded angles, never caudate, and nearly averaging in size that of the white blood- corpuscle. They contain a variable number of granules scattered without order through their substance, but generally leaving a free circlet at the periphery. We have never seen a dis- tinctly defined nucleus within them ; acetic acid simply renders the cell- wall more trans- parent, and exhibits the granules more clearly. (3.) Irregular particles. Shapeless particles, flat, pale, and on an average of less size than the cells, are sometimes seen. These are pro- bably, in part at least, the walls of disinte- grating cells ; whether they eventually go to form granular matter is a point open to inquiry, but appears to us probable. With these the substantial constituents of tubercle, are sometimes accidentally associated. (4.) large fat globules; (5.) /j/cr/c5 of cholesterin ; (6.) amoiyhous saline paiiicles ; (7.) melanic cells and granules. Nothing having the attributes of a stroma can be detected in tuberculous matter; but a semi- transparent substance, more or less solid, slowly soluble in acetic acid, absolutely structureless and amorphous, holds its elements together. Neither does tubercle ever contain vessels of new formation ; and the imprisonment by tu- berculous deposit of natural capillary vessels, still pervious, is comparatively rare and acci- dental ; there is a tendency, constant in action, and eventually irresistible, to obhteration of the vessels around and amid which the blastema of tubercle is thrown out. A new vascular system, we are aware, has been found to originate in the vicinity of tubercle ; but this development takes place within common in- flammatory exudation matter. In the same way there may be found on the confines of tuberculous matter compound granule-cor- puscles, pus-corpuscles, with, of course, the ultimate elements of the tissues implicated. In the same natural texture with such tuber- culous matter as we have now described, are very frequently found certain small bodies vary- ing in size from that of a pin's head to a very small pea, of greyish-white or greyish tint and glistening aspect. These bodies are known as the semi-transparent grey granulation ; and their affinities to yellow tuberculous matter have been a theme of constant disputation from the period at w hich tubercle first became the subject of close study. While some regard them as products of common inflammation (Schroeder van dcr Kolk, Andral) ; while visionaries are found (Kuhn*) to maintain that their relationship is closest to the Nema- zoa of Gaillou (a class of beings forming a link between vegetable and animal existences) ; while a reasoner habitually most cautious (Carswell) regards them in some situations — the lung — as an admixture of mucus and true * Gaz. Med. de Paris, t. ii. p. 342. 1834. 106 PRODUCTS, ADVENTITIOUS. tubercular matter, in other situations as an admixture of the same matter and coagulable lymph ; the majority of observers hold them to be actual tubercle in an early stage of development. The latter opinion under cer- tain modifications, we believe, for reasons which will presently appear, to be the true one. These bodies occur in different organs and textures in association with yellow tubercle ; they are more or less transparent, and, though in their own substance of light greyish colour, their translucency sometimes gives them in ap- pearance the tint of the circumjacent structure ; their section exhibits a smooth and close sur- face ; hard as cartilage almost in some instances, and invariably remarkable for firmness ; in gene- ral outline seeming roundish, yet in reality of somewhat angular form ; and adhering so closely to the adjoining tissues that they cannot be removed without particles of these, they have a striking tendency to accumulate in groups. Now the motives for connecting this pro- duction pathologically with yellow tubercle, and regarding the one as a phasis of the other, are derived as well from (a) naked-eye observa- tion and considerations of general pathology, as from (b) microscopical examination, (a) Common yellow tubercle appears in the sub- stance of the grey granulation at a certain stage of its existence, and gradually (in the lungs and in bone for example) fills the entire space it had occupied. In the lungs the grey granulation follows the same topographical course as yellow tubercle ; originating in the upper regions, it migrates downwards ; and the quantity of the one, as of the other, is greatest at the apex.* Grey granulations are found mixed with yellow tubercle in various organs, and so rare is the development of the one without the other, that M. Louis f only encountered grey granulations without yellow tubercle five times, and the lat- ter without the former once. The material composing the grey granulation also occurs in the form of shapeless masses, and \vhen so de- posited (as in the lungs and lymphatic glands) also becomes the seat of yellow tubercle, (b) Microscopically considered, the elemicnts of the granulation prove the relationship of the two products. A hyaline substance, non-stromal, holds together cells, identical with those already described, mixed (sometimes) with melanic matter in small quantity, and the elementary fibres of the implicated tissue (doubtless the objects mistaken in the lung by Kuhn for vege- table filaments). The proper granular matter of tubercle alone is absent, or present in very minute proportion only. The disintegration and breaking up of the cell-structure, and the exudation, further, of blastema, which, incapa- ble of furnishing cells, generates granules, cause the appearance of yellow opaque amid grey semi-transparent tubercle. It appears, then, that the two conditions, grey and yellow, are stages of each other. But * In acute niiliaiy tuberculization, however, the grey granulation, scattered equably tlirougli the various parts of the lung, is deposited in an isolated manner. t On Phthisis, Transl. p. 2. is this sequence necessary ; must grey matter precede the yellow in the order of evolution ? No : for in some textures, as the lymphatic glands, grey matter is very rare ; in others, as the brain, it is not, as far as we know, ever seen, though yellow tubercle is not of very uncommon occurrence there in infancy ; and, lastly, in the lungs, tubercles are sometimes found of the minutest conceivable size, yet yel- low throughout their entire substance without the least grey appearance. It follow s, then, that the ordinary first or grey stage may be to all seeming passed over, — an idea by no means repugnant to reason, inasmuch as such a state of things would naturally occur wherever a peculiarly low crasis of the system leads to primary production of granular matter in ex- cess and unusually rapid disintegration of cells. Another kind of granulation occurring in the lungs, first described by Bayle, and by him supposed to be composed of adventitious carti- lage, has been by almost all writers confounded with the common grey production. This va- riety is, w e believe ourselves justified in affirm- ing, of great rarity ; at least we have met with but one example of it — some years since at the Hospital for Consumption. In this instance the granulation was of round or oval form, as large as a good-sized pea (all present very uniformly so), of dull white colour, opahne without yellow points, present in moderate numbers, disseminated equably through all parts of both lungs, not grouped, but deposited solitarily, producing no visible change in the circumjacent texture, and unassociated with yellow or grey tubercles. Bayle, maintaining the obviously erroneous opinion, just stated, of their anatomical nature, connected these bodies pathologically with phthisis; Laennec regards them as a modification of the common grey granulation ; our own opinion on the point is unformed. Among the numerous published analyses of tubercle, we have for some years been in the habit of referring to that of Preuss* as at least the most elaborate in existence. According to the results of this analj'st, one hundred parts of tubercuhzed pulmonary substance consisted of Water . . * . . . 79.0.5 Tuberculous matter . . . 13.52 Fibrous residue, vessels, bronchi, &c. 6.53 One hundred parts of the fibrous residue consisted of Fat 4.13 Substances yielding gelatin by boil- ing 20.G7 Substances yielding no gelatin by boiling ..... 75.20 The tuberculous substance itself, without water, contained : Snhstonces soluble in hot alcohol onlj/. Cholesterin 4.94? Ill cold alcohol and not in icatcr. Oleate of soda .... 13.50 * Preuss, Dis. Inaug. Tuberc. Pulmon. Crudorum Analysis Chemica. Berol. 1835. PRODUCTS, ADVENTITIOUS. 107 In cold alcohol and in water. A peculiar substance {Phi/matin)'\ Chloride of sodium . . '18 46 Lactate of soda . . • j * Sulphate of soda . . . J In water but not in alcohol. Casein "| Chloride of sodium . . * I 7 9D Sulphate of soda . . . J * Phosphate of soda . . . J Neither in alcohol nor in water. Casein (altered by heat) . Oxide of iron .... Phosphate of lime . . * - 65 1 1 Carbonate of lime . . . j * Magnesia Sulphur 99.91 Phymatin {(pvtia, a tubercle ; like pyin, the discovery of Gueterbock,) is described as a pe- culiar extractive matter, not precipitated from its solution by extract of galls, very little by neutral acetate of lead and nitrate of silver, but, on the contrary, very copiously by basic acetate of lead ; sulphate of copper gives no precipitate, according to Gueterbock ; a white flocculent one, according to Preuss. The main protein-constituent of tubercle appears, from the above analysis, to be casein. But nume- rous chemists question the correctness of this analysis, precisely in respect of the casein ; and it certainly appears proved that Preuss had not furnished sufficient evidence of the nature of the protein-compound contained in tubercle. Scherer* has endeavoured to establish the re- lations of this organic material to protein, and dwells upon the fact that according to the lo- cality of the diseased product this may be theoretically formed by adding to or taking from protein a varying number of atoms of oxygen, hydrogen, and carbon. The formula of protein, as givep by different chemists, it is to be remembered, varies, — its very existence is made matter of question ; we are, therefore, unable to discover in what manner the che- mistry of the formation of tubercle can be considered to be advanced, or to be likely at present to be advanced, by speculations of this class. The insignificance of such hypotheses becomes apparent, too, from the fact that some of the analyses of tubercle differ as much from others as these do from the analyses of cancer ! M. Boudetf finds, with respect to its organic constituent, that tubercle yields albumen and a matter analogous to casehiy under the action of cold water, and is reducible to a substance having the characters of fibrin ; he further dis- covers that casein, insoluble in crude tubercle, becomes soluble eventually through the deve- lopment of alkali: a series of propositions more striking than satisfactory. * Simon's Chemistry, vol. ii. p. 430. 1846. t Bulletin de I'Acad. Royale de Medecine, t. ix. p. 1160. Tubercle is insusceptible of growth, properly so called : it increases in size by accretion of new particles or by gradual coalescence of mi- nute masses, at first separated from each other by appreciable intervals. In the lung the latter mode of enlargement is invariably observed, where the tubercle is of any size ; hence the constancy of septa, as already referred to. Tubercle,having subsisted for a variable time in the firm (or, as it is called, crude) state, tends to undergo either of the following changes : — (1.) to become invested by a cyst ; (2.) to decay by a process known as softening. (1.) In certain situations, more especially the bronchial and mesenteric glands and bones, tuberculous matter, undergoing gradual in- spissation, occasionally becomes invested with a cyst (of fibrinous origin), which cuts it off from the surrounding textures, and renders it, comparatively speaking, innocuous. (2.) When tuberculous matter has existed for a certain but variable period in the state of firmness or " crudity," it in the vast majority of cases softens. In this new state its physical characters are either very closely similar to those of thick deep-yellow pus, or (which is more common) it seems to consist of two materials, the one soft, friable, and caseiform, the other more or less watery and transparent, mixed together in variable proportions. Com- mencing by possibility at any part of the tubercle, this process commences more com- monly towards the centre, or at least within the area of the tubercle, than on its confines. The process of softening must either be of intrinsic or extrinsic origin. Laennec, looking on tubercle as vascularized, presumed the change to be intrinsic, and dependent on some morbid condition of vascular action ; an hypo- thesis which existing knowledge refuses utterl;- to justify. Other pathologists taught that all changes in the consistence of tubercle de- pended on actions going on in the surround- ing textures — suppurating, infiltrating, disin- tegrating. The latter doctrine is doubtless correct in part ; a tubercle, softened at the periphery or even in its central parts, when these are permeated by natural textures, has in many instances simply undergone disinte- gration from saturation with fluids produced by those textures. But when a large mass of tubercle (as in the brain or in a lym- phatic gland) liquefies in the centre, where it is absolutely beyond the reach of influence from the circmDjacent tissues, some intrinsic change has evidently occurred. And this in- trinsic change seems assimilable to that effect- ing softening of fibrinous clots in the veins, and is in intimate nature probably chemical. Tubercle, once deposited, is not necessarily a fixture in the locality it occupies ; on the contrary, its removal from the body is fre- quent, and occurs under diflferent conditions and in different manners. It is effected ; (a) probably by simple absorption ; (6) by absorp- tion combined with so-called " transforma- tion ;" (c) by elimination. («) Existing knowledge concerning the simple absorption of tubercle is far fi'ora satis- 108 PRODUCTS, ADVENTITIOUS. factory. Our own belief (which is firm) in its occurrence rests upon the following facts and arguments. 1 . Rabbits submitted to influences which, experience has proved, unfailingly lead to the development of tubercle in the liver and elsewhere, have subsequently been placed in conditions favourable to health, eventually been killed, and no traces, or the merest traces, of tubercle been discovered in their bodies. (Jen- ner, Baron, Carswell.) 2. Miliary tubercles, developed in the substance of pleural or peri- toneal false membrane, disappear in cases where the latter becomes cellulo-serous in texture. 3. Tuberculous matter disappears from the substance of enlarged strumous glands. 4. We have seen and satisfactorily observed cases of tuberculization of the bron- chial glands in children, in which (while the local and general symptoms of phthisis were fully developed, and the physical signs of marked enlargement of the bronchial glands were no less distinct) recovery in respect of symptoms has occurred, coevally with modi- fication and ultimately disappearance of those physical signs. Such cases are unfortunately rare. o. And, again, we have found the phy- sical signs of induration at the apex of a lung in "persons labouring under the local and general symptoms of phthisis, and belonging to a tainted family ; and these signs have totally disappeared in company with the train of local and general symptoms. The event is, no doubt, singularly rare ; and the disappearance of induration-signs may, by the sceptical, be referred to the cessation of congestion. But congestion has its special signs, which were not present in the cases we refer to ; and con- gestion at the apex is, in the very great ma- jority of cases, of tuberculous origin. 6. Andral and Reynaud attempt to trace certain furrowed and excavated appearances of pul- monary tubercles to a process of absorption, but they do this dubitatively, and the point has not been investigated by others. (b.) Of the removal by absorption of the animal ingredients of tubercle, while saline particles are deposited in abundance (so- called '^transformation"), no doubt can be entertained. The gradual change of the tuber- culous matter may be traced from a condition of mere desiccation with greasiness to the feel, to that of osteo-petrous substance. The traces of animal material may eventually almost wholly, if not wholly, disappear ; for Thenard found' that while " crude" tubercle contained 98.15 per cent, of animal and 1.85 of saline matters, cretaceous tubercle furnished but 3.0 per cent, of the former and 96.0 of the latter. The production of this change in tubercu- lous matter is very frequently (but certamly not always — witness the case of the mesen- teric glands) connected with the presence of common plastic exudation in the surrounding natural texture. This exudation-matter gra- dually hardens, eventually assuming the fibrous condition, and possessed (like all similar exu- dation) of strong contractile properties, pro- bably facilitates the absorption of the enclosed tubercle by the pressure it exercises. But absorption may proceed further. The cretaceous, calcareous, or osteo-petrous sub- stances, representatives of bygone tubercle, sometimes totally disappear; and, at a later pe- riod still, the plastic fibrinous substance is itself removed. The part where all these changes have occurred (in the lungs for example) may even appear healthy; but on close examination puckering (parenchymatous, we mean, not pleural) is discovered in a spot, where obhte- rated vessels and bronchial tubes converge, as the indelible evidence of the morbid con- ditions that have preceded. This puckering and obliteration have (as we believe errone- ously) been ascribed to the cicatrization of cavities. (c.) The elimination of tuberculous matter by excretion is effected from free surfaces, or from the stroma of parts and organs. 1. Excretion of tuberculous matter, without breach of surface in the part supplying it, oc- curs in the uterine, renal, and pulmonary pas- sages,— never, so far as we have ourselves observed, in the intestines. The occurrence is, under all circumstances, rare. 2. The elimination of tubercle from the stroma of parts involves the destruction of tissue by an ulcerative or gangrenous process. Such elimination takes place either when the cretaceous change has occurred, or independ- ently of any such change. Of the former (the rarer of the two) the escape of cretaceous masses from the bronchial glands through an ulcerated opening in the trachea, furnishes a striking example ; the expectoration of such masses from the lungs themselves is extremely rare, while, on the other hand, these organs supply the most important illustration of eli- mination of unchanged tuberculous substance. Softening of tuberculous matter being com- plete, the natural textures contained within the area occupied by that matter have likewise lost their consistence, as a result of infiltration with morbid fluids and of imperfect nutrition. Ulcer- ative destruction readily sets in; minute bron- chial tubes are in consequence opened ; through these the softened matter and (as is proved by microscopical examination) fragments of the parenchymatous fibrils and capillaries of the lung are evacuated. An excavation (cavity or cavern) in the pulmonary substance is the result. When a cavity is of recent date, its walls, smooth and even, are commonly lined, more or less completely, with plastic exudation, fragile, whitish, and opaque ; but the pulmonary tissue is in some instances bare and unprotected. The walls of cavities of old date, firm and resisting, are lined with a membrane, divisible into two strata — the external dense, greyish, and fibrous, the internal soft and velvety, deposited conti- nuously or in patches on the inner surface of the former. Or (as existed in one-fourth of the old cavities examined by Louis) the walls may be totally free from any membranous in- vestment. The walls are uneven, irregular, and coated commonl}' by bands composed of pulmonary substance (rarely containing per- meable vessels) studded with tuberculous PRODUCTS, ADVENTITIOUS. 109 matter. Such cavities generally communicate with others, and always with bronchial tubes. Cavities vary in size from that of a nut to very nearly that of the lung itself ; the edges of the lobes being rendered continuous by pleural false membrane, and the pulmonary texture destroyed from base to apex. They form first at the apex, and more readily at its posterior than at its anterior aspect, and very rarely advance jsari passu in both lungs. When of recent origin they contain pus and softened tubercle, with or without foetor, in the dif- ferent conditions already described. When of old date, on the contrary, they contain a dirty, thin, greenish fluid, with grumous particles suspended in it, and stained, or (as is most common) not stained, with blood. In rare instances fibrinous coagula, firm and adhe- rent*, which may even be the seat of vascu- larization f, are found within them ; and still more rarely portions of pulmonary substance, either gangrenous % or free from such change. Vegetable productions of low type are often to be found amid the contents or upon the walls of cavities of a certain age. The course and eveiit of cavities are points of extreme interest. 1. Their most common course by far is to in- crease in size, through communications formed with softening tubercle on their confines. 2. They become stationary, the tuberculizing process having ceased in their neighbourhood. The double membrane lining them acquires more and more perfectly the characters and properties of the structures forming the inner wall of fistulae ; and they cease to exercise de- leterious influence of any serious kind. The cure of phthisis is sometimes, according to Laennec, accomplished in this manner; but it is obviously necessary for the cure of the dis- ease, not only that the cavity should itself become innocuous in the manner described, but that tuberculization should cease in the rest of the lung — that the rest of the lung should be healthy. Now we regret to be forced to state that during a search of several years carried on under peculiarly favourable circum- stances, we have failed to discover a single ex- ample of this fortunate coincidence ; nor do we believe (while to deny its possibilifi/ would be rash) that evidence has ever yet been furnished of its actual occurrence. ^ * Univ. Coll. Museum, f Louis. X Some time since a patient of ours expectorated a fetid mass, about the size of a large pea, present- ing under the microscope, and even to the naked eye, the characters of pulmonary tissue. This is the only instance of the kind that has ever occurred to us. § M. Louis relates a case (Op. cit. Transl. p. 19, case 3) in which a solitary excavation lined y^-ith. pseudo-membrane of recent origin, existed at the apex of one lung in the midst of healthy tissue ; and considers it presumable that, if the patient had survived a short while longer, the membrane in question would have assumed the fistulous charac- ters we have above described : under these circmn- stances a cure of phthisis would have been accom- phshed. But in the first place it was not accom- plished ; in the second it appears extremely doubtful 3. That tuberculous cavities are capable of cicatrizing, and that they actually do cicatrize with very considerable frequency, was taught by Laennec, and has since his time been almost universally accepted as matter of established doctrine. We must nevertheless affirm that we have ourselves in vain sought for a single spe- cimen of cicatrized tuberculous cavity; nor can we avoid deliberately questioning the fact of such cicatrization ever occurring. The shape of fistulous cavities, the smooth- ness and polish of their internal surface, the fact that atmospheric pressure must act con- stantly on that surface, and, in fine, their struc- tural analogy to fistulae in other parts of the body, form so many a ^?n"ori arguments against the possibility of cicatrization. Laennec saw their force ; but certain observed facts led him to disregard them, and admit the reality of partial and complete adhesion of the apposed walls of cavities. These facts are as follow. (a.) In the latero-posterior part of the upper lobe of a particular lung appeared a deep de- pression, containing a material solid and resist- ing. From the centre of this depression a white opaque lamina, about half a line thick, and of cartilaginous consistence, extended in- wards, divided into two parts, and then re- united, thus forming a small cavity, which was filled with a yellowish-white, opaque, friable substance, much drier than common tubercu- lous matter. Here was (according to the as- sumption) a partially closed pulmonary cavity ; and, be it observed, Laennec never saw more than one such case. ()8.) In the upper part, especially, of the upper lobes, Laennec frequently saw t^ands or nodules composed of condensed cellular or " fibro-cartilaginous " tissue, with a depres- sion on the superjacent pleural surface, of variable depth, puckered, firm, and uneven, and with adhesion of the pleura at the corre- sponding point; the converging bronchial tubes being somewhat dilated in the vicinity, and obhterated in the exact site, of those bands cr nodules. Further, these bands or nodules were always situated at the depth of half a line, a line, or two lines at furthest, from the surface of the lung; and were or were not distinctly continuous with substances of simi- lar nature on the surface of the pulmonary pleura. Here were the assumed evidences of complete closure of cavities, — the puckering and thickening on the pulmonary surface showed that cicatrization had occurred un- derneath, but did not (as Laennec was often erroneously said to have maintained) in any measure constitute the actual substance of cicatrices. But it may be objected to this doctrine : — that the superficial puckering is often seen, where subjacent cellular bands or nodules cannot be discovered ; — that it frequently (for reasons which ISL Louis has anticipated, but not, as we thinl?, satisfactorily set aside) that the exca- vation was of tuberculous rather than of purulent origin ; and in the third the eventual assumption of the fistulous characters, in this particular case, is matter of hypothesis. no PRODUCTS, ADVENTITIOUS. exists at the base of the lung, where cavities are excessively rare ; — that such puckering is so common that, if it really signify closure of cavities, this must be admitted to be an every-day occurrence — an admission to which the laws of general pathology and special clinical experience are equally opposed ; — that the alleged cicatrices are always (as in- sisted upon by Laennec himself) either ac- tually under, or only a line or two distant from, the pulmonary surface, whereas cavi- ties are frequently seated deeply in the lung ; — that Laennec's clinical evidence in support of closure of cavities is exceedingly defec- tive, and that were cicatrization so common, as on his principles it must be, the oppor- tunity of tracing the jyr ogress of contraction during life would frequently occur, whereas it has certainly never yet occurred to ourselves, nor (so far as we are aware) as ^natter capable of demonstration to any one else. Laennec's anatomical facts were correctly observed, but he misinterpreted them patho- logically. The cellulo-fibrous bands or no- dules he noticed appear, in truth, to be formed in either of the three following ways. (I.) They are primary productions, generated quite independently of tuberculization ; — re- sults of local inflammation perfectly assimi- lable to the bands permeating more or less completely the entire substance of the lung, in certain cases of general chronic sub-inflam- mation of the organ. (2.) They are produced in the manner already explained (p. 108), in connection with tubercle undergoing absorp- tion. (3.) They are altogether extra-jml- monarij productions, and their apparent posi- tion within the parenchyma of the lung, a fallacy more or less easily exposed. Under all these circumstances their alleged direct relationship to cavities is matter of pure imagination ; but the last mentioned con- dition of things only (which has been in- sisted on principally by M. Fournet), needs to be dwelt upon here. As a preliminary point, let it be observed that viscera invested with serous membrane are liable to undergo indentation by the con- traction, and in the site, of plastic exudation. Even the liver, dense as it is, we have occa- sionally seen pretty deeply indentated in this manner ; more frequently is this observed in the spleen, but still more so (obviously from the yielding character of its texture) in the lung. Now, in the particular cases we have in view, the following points may be traced. ]. Pleurisy occurs, local or general, with or without liquid eff'usion. 2. The resulting plastic exudation penetrates or not into sulci on the pulmonary surface formed by creas- ing ; these sulci are deeper if liquid efllision has occurred, than under the contrary circum- stances. 3. The plastic exudation is thicker at some points than others, and there excess of depression takes place, because its own contractile force, and the force resisting at- mospheric (excentric) pressure, are both greatest there. 4. Processes from this super- ficial exudation penetrate into the sulci (we have seen them three quarters of an inch long). 5. The thinner peripheral portion of the plastic exudation on the pulmonary sur- face becomes by-and-by cellular in texture, eventually undergoes more or less complete absorption, and the immediately subjacent portions of lung rise up on the removal of the pressure ; the central and thick part of the exudation (itself become meanwhile more or less distinctly fibrous in texture) appears deeper than ever in the lung, while the per- fect adhesion of the edges of the sulcus in which it lies, renders the illusion complete as to its being seated in the actual substance of the lung. 6. The adjoining pulmonary tis- sue may be simply condensed, or may be solidified with infiltrated plastic exudation ; in either case (but especially the latter) obli- teration of the minute vessels and bronchi takes place. The pulmonary tissue, yet be- yond this, may become emphysematous. The more frequent occurrence of these appearances at the apex than elsewhere, is the obvious consequence of the great proportional frequency of local pleurisy there, — itself de- pendent on the frequency of irritation set up by tubercles in the neighbourhood. The condition of the minute bronchi in the impli- cated parts, is of itself a strong argument in favour of the doctrine we have set forth ; those tubes are contracted and obliterated as they would be from pressure and disuse, they are not abruptly cut across, as they would be were Laennec's cicatrization-theory in accordance with facts. According to M. Fournet, the deep sunken, fibrous nodule may become the interstitial seat of puriform or of calcareous deposition. In this way he explains Laennec's solitary example of partially closed cavity, already referred to. We have not seen this condition ourselves : the thing is no doubt possible, but it must be very rare. In taking leave of this question we would ob- serve, that the nature of this work has pre- vented us from giving it the full development it really merits, but we trust enough has been said to make the main fact intelligible. That fact is doubtless disheartening to the thera- peutist ; and we should regret any active part we may have taken in establishing it, did we not look forward on some other occasion to proving, that anatomical cure by absorption, in the manners already described, is of more common occurrence than is generally sup- posed. Many of the influences, irritative and me- chanical, exercised by tubercle on surrounding textures, have been spoken of in the fore- going pages ; the generation of new vessels attending the progress of tuberculization in the lung, will be touched upon in the section on New Vessels in another part of this article. § 3. PURULENT DEPOSIT, OR PUS. Pus is a fluid of whitish-yellow or greenish colour, and homogeneous aspect ; of faint, pe- culiar smell, when warm ; inodorous, when cold ; of creamy consistence ; and of sweetish, or sometimes saltish, taste. PRODUCTS, ADVENTITIOUS. Ill Pus consists of a liquid part (liquor puris) holding in solution organic principles and in- organic salts ; and of a solid part (corpuscles) held in suspension in the Hquor puris. These constituents separate spontaneously, after re- moval from the body, with a degree of slow- ness increasing as the purity of the pus ; when the liquor puris is in excess, the corpuscles sink rapidly. The corpuscles are not sepa- rable from the liquor puris by filtration. Pus does not naturally contain gas of any kind (J. Davy). Its specific gravity ranges between 1042 and 1021, the weight most commonly- observed being about 1030. Four kinds of organic corpuscles are found in pus : (1.) Proper pus-corpuscles ; (2.) Py- oid corpuscles ; (3.) Granules ; (4.) Compound granule-corpuscles. (1.) The proper pus-corpuscle is a body of tolerably spherical outline, unless when acci- dentally flattened or otherwise altered in shape by the pressure of adjoining corpuscles ; its edge, slightly dentated, as we have commonly seen it, may be perfectly even ; its surface finely granular-looking. The corpuscle is (commonly, but not always,) moderately trans- parent, subjacent bodies being visible through it, as is particularly obvious when a weak iodine-solution has been added to the fluid. The diameter of the corpuscle varies from the to the y-jjVo inch, — averaging about the -^-oV-o* substance is somewhat elastic. It never, as far as we have seen, presents a narrow edge to the eye, in the manner of the red corpuscle of the blood. The contents of the corpuscle are semi- fluid and solid. The semi-fluid substance seems of slightly gluey consistence. The solid contents are the nucleus or nuclei. It was long taught that if the pus examined be recent, and chemically unchanged, the nucleus is not perceptible even with strong magnifying powers. This is now known to be erroneous ; we have, with a glass magnifying only 400 diameters, detected a nucleus in laudable pus of neutral reaction, immediately after removal from the body.* But, under the influence of dilute acetic acid, the nucleus is more fully brought into view, and is seen close to the cell-wall, in the form of a bipartite, tripartite, or quadripartite body (more rarely a single one), all the divisions of which he nearly on the same plane side by side. Each division of the nucleus is smooth, circular, or slightly oval, and biconcave. The central depression, which exists as a conse- quence of its biconcave form, either appears opaque, while the surrounding part is clear and transparent, or the former is transparent and the latter opaque, — ditferences depending on variation of the focus of the microscope. The surface of the nucleus is very finely granular ; its diameter varies from the o-Vo to the «oVo inch. * The facility of its discovery depends upon the transparence and thinness of the cell-wall ; and the amount of these, upon the youth of the corpuscle. In our work on Cancer (Jig. G) are figured nuclei visible without the aid of acetic acid. (2.) Under the name of pj/oid, M. Lebert* distinguishes a corpuscle smaller than that just described ; spherical in shape, tolerably trans- parent, rather of solid than liquid consist- ence ; containing from four to ten granules or more in their interior, and wholly unprovided with nucleus, acetic acid simply rendering the corpuscle more transparent. These bodies, resembhng most closely the cells of tubercle (p. 105), are larger and more spherical than these : so great is the similarity, that M. Lebert was at first led to consider the pyoid cor- puscle peculiar to tuberculous pus ; but, sub- sequently finding it (as we have also done ourselves) under circumstances excluding the idea of tubercle, has relinquished this notion. (3.) The elementary granule seen in pus is of spherical shape ; it is never cupulated, so far as we have seen, and is less than half the size of the nucleus of the pus-corpuscle, ave- raging the Y44o-o of an inch in diameter. These granules are obviously not, as was once maintained, detached nuclei floating in the liquor puris. They are either single and soli- tary, or (less frequently) collected in irregular groups. Their composition varies, as they are sometimes soluble in aether, and sometimes exhibit the reactions of a protein-compound; this chemical difference is not always con- nected with any physical peculiarity, which the eye at least can detect. (4.) The compound granule-corpuscle (com- pound inflammation-globule ; Gluge) does not occur in large numbers in pus ; many drops may be examined without a single one pre- senting itself. This corpuscle is of spherical, and slightly irregular, form, ranging from rsVo to TrVij of i"ch in diameter (fig. Fig. 92. Compound granule-corpuscles (magnified 400 diams.). a, in the natural state, diam. =1330 to of an inch ; h, corpuscle about to undergo rupture, the invoiucrum being more transparent, and the gra- nules larger, darker, and more prominent ; c, a cor- puscle treated with dilute acetic acid, the invoiucrum being rendered transparent, and several nuclei ap- pearing in its interior. 92) ; and composed essentially of granules and an invoiucrum. The invoiucrum is not dissolved by water, and simply rendered trans- parent by acetic acid ; the granules vary from ten, to twenty or thirty, or even many more in number. Occasionally the action of acetic acid discloses a single, double, or multiple nucleus lying close to the invoiucrum. The granules are likewise kept in situ by a fluid of thickish consistence, in which, if few in num- ber, they may be seen to move. The course of formation of these corpuscles seems to be, — agglomeration of granules from exudation matter, investment with a membranous wall, production of a nucleus. * Physiol. Patholog. t. i. p. 46. 1845. 112 PRODUCTS, ADVENTITIOUS. Fat occurs invariably in more or less quan- tity in pus, and exhibits itself under the micro- scope, under the forms of molecular granules, as above referred to ; oil globules ; crystals of cholesterin. Saline crystals occasionally occur in pus, especially in certain unhealthy varieties of the fluid. When they exist, some peculiar cir- cumstances have probably caused unusually rapid, or otherwise modified, evaporation of the liquor pun's. Infusoria (monads and vibrions, especially the vibrio lineola) occur in pus : we are un- able to affirm whether their presence is always an evidence of decomposition in the pus itself. The attempt, made by Gruithuisen, to dis- tinguish various fluids by the characters of the infusoria developed within them, has not led to any satisfactory results. Pus, when recent and healthy, has a slightly alkaline reaction ; we have known it neutral, however, in cases where there was no reason to believe any chemical change had occurred. It readily becomes acid from the development of an acid — the lactic it is supposed : the change from one to the other reaction, evi- dently depends, in some cases, on a primary change in the constitution of the pus at the moment of generation ; for we have found pus from the same wound, sometimes alkaline, sometimes acid, though taking all precautions to ensure its examination at the moment of production. The published analyses of pus are extremely numerous. Among the most recent and care- fully conducted are several by Dr. Wright*, of which the following may be selected as specimens ; it is clear that the chemical con- stitution of the fluid must vary somewhat with the locality from which it has been de- rived, inasmuch as pus can very rarely be obtained free from minute quantities of the textures or secretions in connection with which its production has occurred. Pus from a Vomica. Pus from a Pus from a Psoas Mammary Abscess. Abscess. Water 894.4 885.2 879.4 Fatty Matter Cholesterin 17.5 1 5.4j 28.8 26.5 Mucus 11.2 6.1 Albumen - G8.5 63.7 83.6 Lactates, carbon- ates, sulphates, and phosphates of soda, potash. and lime - 9.7 13.5 8.9 Iron - - - A trace. Loss - - - J 3.3 2.7 1.6 Some of the discrepancies in the results given by various experimentalists, doubtless depend in no small degree on the differences in the manner of conducting their analyses. Making allowance for these sources of error, it may be inferred that liquor puris consists • Medical Times, January, 1845. of water varying in proportion from 76 (Von Bibra), and 82 (Dumas), to 90 (Lassaigne, Pearson, and Von Bibra*) per 100, of dis- solved albumen, of fibrin, fat, and extractive matters, A peculiar principle (precipitable by acetic acid and by alum) has been assigned to pus, under the name of pt/in, by Gliterbock : that such a special substance exists independ- ently of the means employed to procure it, has been questioned or denied by Valentin, Dr. John Davy \, and others. At the present hour the real presence in pus of the principle, described under this name, is admitted by chemists ; it is said (probably pro teynjjore) to be tritoxide of protein. Glulin is enumerated by Martins J among the constituents of the pus of empyema ; its existence must be an exceptional occurrence. Phosphoric, hydro- chloric, and lactic acids in union with lime, potassa, soda, magnesia, and ammonia, form the ordinary saline elements of the fluid. Oxide of iron, though put forward as a constant in- gredient by Cruickshank, Koch, Krauss, Gobel (in the horse), Pearson, and Gliterbock, is in all probability only present in instances of ac- cidental admixture of blood. The micro-chemical properties of the pus- corpuscle are important. Pure water exercises no obvious influence on it for days, even, ex- cept that of rendering the nucleus more visible, and slightly increasing its size by passing through the cell-w^all by imbibition. Saturated sugar- water, blood, mucus, and saliva, unless (as observed by Henle) the latter be acid, produce scarcely any alteration in the cor- puscle. Urine gives it an extremely ragged outline in the course of a few days (earher if it be alkaline), and eventuall}-^ breaks it up completely. Alcohol slightly corrugates, with- out dissolving it. Under the action of acetic acid the corpuscle loses its granular appear- ance, commonly undergoes a change of bulk ; and the distinct outline of the involucrum fades away, while the nucleus, simple or com- pound, becomes clear and distinct. What is the nature of these changes ? The removal of the granular aspect of the corpuscle is not readily explained. We were at one time dis- posed to regard it as produced by the simple unfolding of the involucrum, caused in turn by imbibition of the fluid re-agent, — believ- ing that the granular appearance arose simply from a corrugated state of the surface of the involucrum. But the uniformity of the gra- nular appearance, its constancy of occurrence, its extreme delicacy, and the fact that it is not removed altogether, no matter how dis- tinctly the corpuscle be swollen by imbibition, appear to throw doubt upon this view, and render it more probable, if not actually cer- tain, that it depends on the presence of mo- lecular matter within the involucrum; — the change of bulk is sometimes one of increase, sometimes one of decrease, — a difference which has appeared to us traceable to the * Untersuch. iiber einige verschiedene Eiterarten. Berlin, 1842. t Physiological and Pathological Researches. J Annalen der Pharmacie. PRODUCTS, ADVENTITIOUS. 113 var \ing degrees of dilution of the acid. That the involucium fades simply, without being, as was at one time supposed, destroyed, is commonly obvious on simple inspection ; it appears as a sort of thin, transparent halo round the nuclei. But, were there any doubt, this would be removed by the addition of solution of iodine *, which restores the clear definition of the cell-wall. The fading of the involucrum is, however, an early stage of so- lution ; for, if much acid be added, the halo disappears and cannot be restored. In re- spect of this disclosure of the nucleus tliree opinions have found their supporters : (a.) that a simple or compound nucleus, pre-exist- ing in either form, is simply rendered visible by the acid ; (b.) that it is exposed and, be- sides, split up into parts; (c.) that it is an ap- pearance altogether produced by the acid. That the first of these opinions is the correct one, appears (if on no other grounds) from what has been said in a previous page on the discovery of the nucleus in recent unchanged pus. Mineral acids, if dilute, do not dissolve the corpuscles ; if concentrated, dissolve them completely. [Caustic alkalies form a jelly with them ; their carbonates, as also muriate of am- monia, change them similarly but more slowly. The action of the latter on pus was observed by J. Hunter on a large scale, and ascribed by him to coagulation of the liquor puris. Dr. J. Davy showed, i)y allowing the corpuscles to settle, decanting the supernatant fluid, pour- ing some of the muriate upon this, and observ- ing that no viscidity followed, until corpuscles had been added, that the change depended upon these. Dr. Wood f ascertained that the muriate causes the corpuscles to adhere with some closeness to each other. Pus-corpuscles contain a very little phos- phate of lime, and consist essentially of a pro- tein-compound. Their constituent substance has been given the special title pur'ium by Koch, piirutina by Michelotti ; a mode of naming it which must be abandoned if, as Lehmann and Messerschmitt maintain, the nu- cleus and involucrum belong to two different varieties of protein, — the former being com- posed of venous, the latter of arterial, fibrin. J But this view is, it is scarcely necessary to add, itself far from being established, — as also that of persons who (imitating Ascherson) hold the centre of the nucleus to be composed of fat, and i"ts peripheral part of albumen. Pus differs chemically from blood in the states of health and of hyperinosis in the proportion of its ingredients, much more than in their nature — as might readily be imagined. But quantitative analyses are as yet so imper- * The corpiiscles, and especially the nuclei, attract the iodine from the fluid in w hich they swim ; for, while they darken, this fluid loses its yellow-brown colour. t De pirns natura atque formatione. (Berol.) X Medicin. Vierteljarhschrift von Roser and Wun- derlich, 18-i-2, S. 247. The same Avriters regard the molecular granules of pus as composed of yet ano- ther variety of proteiu-compound, resembUug Ke- ratin, VOL. IV. feet, that very different general inferences may be deduced from them according to the selec- tion made of published analyses ; — it is true this may also in part depend on the actual vari- ation in the proportions in different specimens of pus. Thus we may prove by one set of experiments that pus contains more w ater than healthy, and d fortiori than hyperinotic, blood ; and, by another, that pus is on the contrary a more concentrated fluid than either. And whichever be the opinion adopted, theoretical explanation and support may readily be found for it. The following general inferences are likewise, we confess, to be accepted with caution. Pus contains more albumino-fibrous sub- stance than the liquor sanguinis of either spe- cies of blood, less than the blood in mass, com- prising the red corpuscles. The latter point obviously depends on the fact that the cor- puscles are, as such (unless jiccidentally and in very minute proportion), retained within the vessels ; whereas pus is formed outside them. But how comes it that pus contains proportionally more albumino-fibrous material than the liquid part of the blood — that part of the blood which is exuded in infian^ma- tion, and which forms the substance for the evolution of the purulent matter ? The pecu- liarity (as suggested by Lebert) is probably due to partial solution of the red-corpuscles in the liquor sanguinis, and transudation ol that dissolved substance ; an explanation not, we may observe, without apparent connection with the established fact of the decrease of red corpuscles in hyperinotic blood. To this source (as w ell as to extravasation) may, perhaps, be referred the occasional appearance of a little iron among the elements of pus. Fat is much more aliundant in pus than in blood ; the high ratio of cholesterin in the former (as ascertained by Valentin *, Von Bibra and Wright) comes in confirmation of the fact established by Becquerel andRodierf, that the ratio of cholesterin in the blood is always in- creased in inflammation. The saline consti- tuents of the two fluids do not differ very materially. Pus possesses a remarkable power of re- sisting decomposition ; at the end of months some corpuscles may still be found unchanged, among others that are dissolved. It even re- tards the putrefaction of substances with which it is brought in contact, as shown by the experiments of J. Hunter and Everard Home. The latter observed that pieces of flet>h placed in fresh pus underwent gradual dimi- nution of weight, and eventually solution, without any evidence of putrefaction being manifested. Ultimately, pus does i)utrefy however ; the occurrence of the change being much hastened by the presence of blood, mucus, or other organic fluids. Aciditv, as already hinted, is one of the earliest signs of the change. * In one of Valentin's Analyses (Repertorium S. 307, 1838) the proportion of cholesterin is so high as 11.86 per 1000. t Gazette Medicale de Paris, 18-14. PRODUCTS, ADVENTITIOUS. The various appearances of pus have yiven rise to its classification into the creamy, curdy, serous, and slimy varieties (Pearson) ; one obviously unfit to represent the existing state of knowledge. It seems better to con- sider pus as of two kinds : I. Simple ; II. With added characters, — the added character being derived either from (A) Substances of known nature, natural or morbid ; or from (B) Sub- stances of unknown nature, called viruses. The pus-corpuscle has uniformly the same character in all descriptions of pus. The dis- tinction of the varieties above enumerated, therefore, can only be microscopically effected (if it can be effected at all) by means of su- peradded elements ; and most valuable these are as diagnostic of its seat and production in many instances. The varieties of pus comprehended in the class (B), differ from those in the class (A), in being inoculahle, — a character dependent not upon any peculiarity of their cell, but upon the associated intangible " virus." Some of the varieties of the class A possess, how- ever, what may be called pseudo-inoculabilitj/, namely, those in which certain parasites are present. The pus of scabies is thus to be propagated by means of its entozoon ; that of porrigo by its entophyte ; but it is clear that the associated pus has in reality nothing to do with the transmissibility of the diseases.* There are three semi-fluid matters, which it is important to distinguish from pus, namely, mucus, softened Jibi-in, and fluid holding epithe- lium in suspension. The distinctive characters most to be relied on are as follow: (a) Mucus. (1.) Pus mixes with water, being at first equally diffused through it, so as to give it a yellowish tinge ; subsequently, the corpuscles fall to the bottom, and leave the supernatant fluid clear and colourless. Mucus does not mix with water, but eventually renders it slimy. (2.) Pus forms an emulsion Avith acetic acid, from which, after a time, the nuclei of the corpuscles are thrown down as a yellow sediment, while the involucra are dissolved. Mucus is coagulated by acetic acid, and forms a membranous flocculent mass ■without mixing with the acid ; at the same time it becomes less slimv and more con- sistent. (3.) Pus forms a ropy mass with the caustic alkalies, or with their carbonates. (B. Babington.) Mucus, on the contrarv, is rendered thinner, and partially dissolved by them. (4.) Pus contains fat removeable by ether, sometimes in such quantities as * Donne describes an animalcule, under the name of Tricomonas vaginalis, as peculiar to the female s}q)liilitic discharge, and constituting the infection- agent. But it is not found in the male, and is often absent in the female ; its powers in the latter quality may be more than doubted. Froriep (Xotizen, 1837, No. 25. p. 40.) thinks the animalcule, peculiarly connected with the female genitals, but not specially with syphilis ;^ and regards it with Ehrenberg (No'- tizen, 1837, Xo. 28. p. 88) as a species of acarus. This matter requires revision ; it has even been sug- gested that Donne and his followers have mistaken ciliated epilheUum-scales (to which indeed the figure of the former bears much resemblance) for animal- cules. to render it inflammable; mucus contains none. (5.) Air bubbles in pus collapse the moment they are formed ; in mucus they re- main for a time — for days even — unaltered. (6.) Equal parts of concentrated sulphuric acid and pus form a dull brown-red solution, becoming paler and turbid by the addition of water ; mucus, on the contrary, forms a pale brown fluid with this acid, w hich remains clear and becomes colourless on the addition of water. (Brett and Bird.) (7.) According to Preuss, pus (as also tubercle) is distin- guishable from mucus by containing iron (which may be shown by inceration and di- grating the ash in gum, hydrochloric acid, di- luted with five parts of distilled water, and then adding a few drops of ferro- cyanide of potassium) : but in point of fact the presence of iron is due to accidental admixture with blood. (8.) Pus pressed between two plates of glass and held before a candle, presents an ii-idescent appearance ; no such effect is ob- served with mucus, (Young ) The state of knowledge concerning the two alleged prin- ciples, mucin and pyin, is too unsettled to allow of just inferences being drawn from the presence or absence of either. Various attempts have been made to dis- tinguish pus and mucus by means of the proper corpuscle of each. The difficulty experienced in the detection of distinctive characters gra- dually led to the suspicion that the corpuscle of both fluids might be one and the same thing; and the inquiries of several competent persons appear at length to have distinctly established the fact, that healthy mucus contains no special corpuscle, but that, under the very slighest irritation of a mucous sm'face, pus, with its special cell, is thrown out, which cell had been mistaken for one peculiar to the natural secre- tion of mucous membranes. The presence of a bougie in the urethra for a very short time suffices to cause the production of muco-pus.* The abundance of epithelium-scales in mucus is sometimes a useful aid in the diagnosis : the nuclei of these scales set free may, doubt- less, also have been sometimes mistaken for special corpuscles. (b.) Softened Fibrin. — The semi-liquid matter frequently found in the centre of co- agula in the veins and heart, was long con- founded (from its colour, consistence, and easy miscibility with water,) with pus ; noto- riously so by MM. Gendrin, Andral, Cruveil- hier, and Magendie. It had been more or less confidently affirmed, however, by MM. Dupuytren, Burrows, Davy, and others, that this matter really consisted" of softened fibrin, and not pus, when Mr. GulUverf gave support to this notion by pointing out the following peculiarities, distinguishing the substance in question from pus : 1. It is not rendered ropy by caustic volatile alkali. 2. It presents no iridescence when pressed between plates of glass before a candle. 3. Under the micro- * That is as far as the generation of pus-corpuscles is concerned ; the production of liquor puria is a more elaborate process. + Med. Chir. Trans, vol. xxii. PRODUCTS, ADVENTITIOUS. scope it is mainly composed of a finely granular mass, and often contains large, irregular, flabby particles, with globules of various sizes. But these globules bear but a very small proportion in number to those in pus ; and, on the addi- tion of acetic acid, they soon disappear, except a few which seem more compact, and require a longer time for solution : they are probably altered blood-corpuscles. 4. Softened fibrin more readily becomes putrid than pus. Fibrin removed from the body and subjected to a blood-heat, begins to change into matter, such as that now described, in forty hours. We have had numerous opportunities of satisfying ourselves of the general accuracy of these observations of Mr. Gulliver; but we cannot accede to the notion that the yellowish- green, soft, sometimes almost diffluent co- agula, frequently seen in veins (coagula which, according to the spirit, if not the absolute letter, of Mr. Gulliver's doctrine, should con- sist merely of softened fibrin and accidentally- imprisoned blood disks ), never contain, and hence never consist, in part, of pus. We have more than once discovered fully-formed and well-conditioned pus-corpuscles in such co- agida, which, upon mere naked-eye evidence, we had regarded as wholly composed of softened fibrin. We refer here to cases where no signs of inflammatory (or other) alteration exist in the coats of the vein, and where those coats appear to have nothing to do with the appearances referred to ; for the corpuscles appear chiefly, or it may be alto- gether, in the centre of the coagula. Now such cases seem to prove one or other of the following three propositions : That corpuscles exist, having all the micro-chemical characters of those of pus, yet in reality of a different nature ; that stagnating liquor sanguinis is capable of undergoing, in its own proper sub- stance, inflammatory changes ; or that the pus-corpuscle is capable of forming, in stag- nating liquor sanguinis through some peculiar influence of non-inflammatory nature. Reason, collateral experience, and the general laws of pathology, point to the second of these pro- positions as the most probable of the three ; but it is wisest for tb.e present, perhaps, to refrain from adopting any one of them. (c.) Ejjithelial Jlidd. — Broken or perfect epithelial scales sometimes accumulate in very considerable quantities in certain serous fluids ; and the resulting mixture cannot with the naked eye be positively distinguished, either by colour, consistence, or odour, from pus. In the Fallopian tube (somewhat di- lated) of an anasarcous woman, who died under our care at University College Hos- pital some time since, we found fluid of this kind, containing (as shown by the microscope, the only test in such cases,) not a single pus- corpuscle, but abundance of epithelium. We have seen the same kind of fluid in the pelvis of the kidnev. The microscopical distinctions of the un- altered red-corpuscle of the blood, and the pus-corpuscle, are so numerous and obvious that they need not be enumerated ; it is im- possible to confound the two objects. The red blood-corpuscles, however, when acted upon by various re-agents (serum, urine, pus, artificially added sahne solutions, &c.) acquire a more or less accurate resemblance to those of pus ; they in truth increase somewhat in bulk, lose their regularity of outline, which becomes ragged, and alternately notched and studded with minute prominences, — appear- ances which have led to very remarkable » errors. Nevertheless, the resemblance is far, even, from seemingly perfect ; the altered red- corpuscle is smaller than the other, and is not minutely granular on the surface: if there be doubt, however, in the case, acetic acid, by dissolving the body (if it be a red-corpuscle), or producing the changes already describetl (if it be one of pus), will settle the question. The colourless corpuscle of the blood in its unaltered state is with difficulty distinguishable from the pus-corpuscle ; the two bodies have, by practised observers even, been confounded. It has the same minutely granulated aspect ; and acetic acid discloses, as in the pus-cor- puscle, a nucleus in its interior. The colour- less corpuscle is smaller than the other, how- ever (the mean ratio of their sizes being as 22 to 27, nearly). The nucleus is either single, bipartite, or tripartite. The process by which pus is formed — in other words, pyogenesis or suppuration — was long supposed to be one of disintegration and solution of the natural tissues. W'e need not devote space to the elaborate refutation of this rude conception : suffice it to say, that pus may be produced for years from mucous membranes, wdthout even abrasion of their surfaces having occurred, and that the ele- mentary textures (e. g. the cellular) may, at the outset of the suppurative process, be shown to have retained all their natural pro- perties. We might, on the score of its obvious fal- lacy, similarly pass by the notion that the corpuscles of pus are simple modifications of the red-corpuscles of the blood ; but as, even recently, symptoms of a return to this pre- viously-exploded idea have appeared on the Continent, a few words on the subject seem called for. M. Gendrin {Hist. Anat. de V In- flammation, 4-c.) taught that in consequence of the stagnation of the red-corpuscles in- duced by inflammation, those bodies are first converted into pus-corpuscles in the interior of the capillary vessels, and, secondly, exude thence into the intercapiliary texture. The experiment upon which the first portion of this doctrine was based has been repeated by Dr. Wood*, Mr. Gulliver, and others ; and either no appearance at all of the alleged puriform matter discovered, or its characters proved to be those of softened fibrin. As respects the exudation of ready-formed [)us- corpuscles, the theory manifestly involves an impossibility, as the structure of the walls of the capillary vessels is too close to perndt the passage of bodies of such dimensions. * Op. Cit. p. 4. 1 2 116 PRODUCTS, ADVENTITIOUS. Besides, M. Gendrin has forgotten to explain why, if the pus-corpuscles escape from the vessels, the blood-corpuscles, of much smaller size, as they are, do not follow abundantly in their track. M. Donne* some time since re- vived the idea of conversion, believing that he had seen red-corpuscles changed into puru- lent in a mixture of pus and blood out of the body: he was deceived by the physico- chemical changes already referred to, which pus, like various other fluids, effects in the blood-corpuscles. The true doctrine of pyogenesis is a modi- fication of that of " secretion " taught by Simpson (1722), de Haen (1756), Morgan (1763), Brugmans (1785), and John Hunter. The direct microscopical evidence, upon which it has been finally established, was ori- ginally and mainly sup[)lied by Wood, Gueter- bock, and Henle. This evidence is to the effect that, as a general fact, the generation of the solid materials of pus takes place wholly outside the vessels in a hyaline blastema. In that blastema granules first appear ; subse- quently, bodies of larger size form, either independently of the granules or around them, and, collecting in variable numbers, or remaining single, present the characters of, and actually constitute, the nucleus of the pus-corpuscle. The involucrum, or cell-wall, next forms ; and, at first clear and trans- parent, subsequently grows granular. One of the readiest plans of observing this series of changes, is by using the exudation-fluid from a blistered surface, — but the same phenomena may be traced on wounded surfaces. The elementary tissues of the body are not at first altered in any appreciable manner by the occurrence of suppuration among themf ; solution of their substance may at length be, and frequently is, more or less completely effected. This solution-process is of triple nature : it is 'physical, in that mere maceration aids in its production ; chemical^ in that in certain unhealthy states of the system, solvent agents, &c. \ are generated in suppuration ; vital, in that the tissues themselves, in certain constitutional conditions, lose partially or completely their force of cohesion. § 4. MELANIC DEPOSIT. Black colouring matter appears under va- rious conditions as a morbid deposit. The only kind strictly belonging to the present head, is true melanic granule or cell-pigment, more or less closely similar to natural pigment. Melanic pigment is essentially composed of extremely minute granules, for the most part contained within cells. The cells are of various shapes, commonly rounded, however; not commonly of caudate form, but often showing a tendency to prolongation in one particular direction. They very rarely con- tain a nucleus. * Arch, de MeU Juin, 1836. f Tfie first cliange discoverable under the micro- scope seems to be loss of elasticity. X Prussic acid, according to Dumas. (Comptes Rendus de I'lnstitut, 1841.) The cells are of blackish, brownish, bistre or yellowish tint, the colour evidently depend- ing on the granules. And these granules are not confined to the cells, but are commonly found, in multitudes, free ; when excessively minute they are the subjects of molecular motion. In some instances cells are not to be discovered at all. Little is positively known concerning the development of melanic pigment, — either of the mode, whether exogenous or endogenous, by which increase of cells takes place, — or of the relationship in which the cells and gra- nules stand to each other; that is, whether the cells are formed around the granules, or the granules generated within the cells. But while it is certain that the cells are deficient in the attribute of permanency, and appear of secondary importance (seeing that the pig- ment character may exist in perfection in- dependently of them through the granules alone), it seems very unlikely that they are truly vegetative. Melanic cells never exhibit any tendency even to cohere — much less to form the basis of a stroma. The chemical composition of this substance is not known with accuracy. Analyses in numbers no doubt have been printed, but none of them are entitled to confidence, — either because they include the composition of associated substances, organic and inor- ganic, or because the black matter analyzed was not really composed of cell-pigment. It is probable, however, that the ultimate con- stituents are the same, and associated in, at least very closely, the same proportions, as of the pigment of the choroid coat. Some of the more important reactions of this sub- stance, as set down many years ago by Henry, may be substantiated readily, and have fre- quently been confirmed by ourselves. A " softened melanotic tumour " was experi- mented on: 1. By filtering through paper, much of the colouring matter remained on the paper, and the colour of that which passed through was rendered much less in- tense ; 2. Boiling does not destroy the colour, not even when a little caustic potass has been added ; 3. It is not changed by acids even when heated, except by strong nitric acid, which turns it yellow ; 4. A stream of chlorine, passed through the liquid, destroys the colour, and throws down light-coloured floc- culi* ; 5. A few grains of corrosive sublimate (nitrate of mercury and nuu'iate of tin also, though more slowly,) precipitate the colour- ing matter and leave the supernatant fluid clear. Black cell-pigment occurs under two chief conditions — iinassociatcd, or associated with other materials. The former condition is ex- cessively rare, and we have certainly never seen it in the human subject, — that is, we have never seen a fluid or solid accumulation of cell-pigment utterly unmingled with other fluids or solids, natural or adventitious : it ap- * Chlorine Avater (which we have used) does not actually destroy the colour, but diminishea its intensity greatly. PRODUCTS, ADVENTITIOUS. 1J7 pears, however, to occur thus in the horse. In the associated form it is of very common occurrence, exhibiting itself in the form of points, spots, layers, or masses, in the sub- stance of natural textures or of adventitious products. In the Jatter condition it has more particularly excited attention, and been de- scribed under the titles of " melanosis," "me- lanotic tumour," " melanoma," &c. A full consideration of the modes of connection of cell-pigment with tumours will be found under the head of "Melanoma" in the sec- tion " Growths." The substance we have just described being the only true black ccU-ingment, appears to be the only one legitimately falling under the present head ; but it is absolutely neces- sary (were it only for the purposes of diag- nosis) that we should briefly consider certain other causes (most ably investigated by Dr. Carswell) of black discolouration. These causes are, (a.) Alteration of the colouring matter of the blood ; (Z>.) Introduction of black-coloured substances from without. (a.) Alteration of hcematosinc. — Stagnation and extravasation, and the action of certain chemical agents, are followed by this alteration. Stagnation produces its effect on the colour of the blood most distinctly in the capillary vessels, is more common in old than in young persons, and attends diseases of the heart and great vessels interferuig with the circulation. Chronic inflammation is the most common immediate cause of the stagnation ; the intes- tinal canal and the lung the most common seats of the altered colour. In the intestinal canal, it is difficult (except by ascertaining the absence or presence of acid) to separate the effects of chemical agency from those of mere stagnation. Extravasated blood (occupying localities altogether removed from the influence of che- mical action not originating in itself, as, for example, in the common cellular membrane,) sometimes undergoes remarkable change of colour, becoming of a pitch black hue. The blackish and slaty discolouration frequently seen in points or patches under the mucous coat of the pelvis of the kidney, and also on the surface of the cortical substance, is evi- dently produced by infiltrated and altered blood. In these cases no pigment-cells are to be discovered, an amorphous granular mass exhibits itself, not materially differing in phy- sical characters (it is not, however, mixed with crystals and fragments of tissue,) from the colouring matter of gangrenous detritus. Chemical action is a frequent cause of black- ening of the blood. Blood poured into the stomach, and sometimes even if retained with- in its veins, is blackened by the gastric juice, either by direct contact or by imbibition. The effects of the acid secretion are precisely such as are producible by acids on blood re- moved from the body. The slaty discolour- ation of the anterior border of the liver, so common an appearance, is similarly explic- able ; the blood in its capillary texture being acted upon by hydro-sulphuric acid gas trans- uding through the adjacent intestines. {b.) Introduction of black coloured substances from without. — The lung (with its appen- dages) is the only organ in which this source of discolouration has been established. Pear- son* was the first to suggest, that inhaled carbonaceous matter was the true cause of the black lines and patches (following the course of the lymphatic vessels) often seen on the surface of the lungs, and of the well- known dark hue of the bronchial glands. Tiiat the colouring material was not of animal na- ture, he inferred from its being insoluble in nitric acid. Pearson's view seemed to derive support from the well-known dark appearance of the morning expectoration of persons who habitually sit up much at night; and from the observation of Laennec, that the peasantry, but little prone to vigil, rarely expectorate dark sputa. But the most absolute collateral demon stration of Pearson's correctness, is derived from the history of a peculiar disease to which colliers are subject. The lungs of in- dividuals affected with this disease become so thoroughly black (Univ. Coll. Museum) as to resemble coal in colour ; and undergo gradual breaking up from irritative and ulcer- ative action.f Now the carbonaceous nature of this material, having been made matter of noto- riety by the experiments of numerous persons, it appeared natural to conclude that it was composed of coal dust inhaled in a state of extreme division. This notion was indeed espoused by Dr. J. C. Gregory j, but proved to be erroneous by Professor Graham^, who showed that the material carried into the lung was none other than the soot or lamp-black formed by the combustion of the oil which the colliers use, suspended from their heads, as they work, in mines where the safet^'-lamp is not used. The constant exposure to the smoke of gunpowder employed for blasting has the same effect, though in a less degree. It remains for us to add, that we entertain no doubt of the black tint, present always more or less extensively in the lungs and bronchial glands healthy persons (generally speaking, in the direct ratio of their ages), being in part due to inhaled sooty matter, but believe that it is likewise in part caused by alteration of the haematin of blood stag- nating in the capillary vessels. This opinion is, however, based on too small a number of micro-chemical examinations to lay claim to general admission. Finally, we may observe that the relation- ship of true melanic cell-piament to the con- stituents of the blood, though made the subject of much dogmatical assertion, is alto- gether unknown. * Phil. Trans. 1813. t The precise anatomical characters of the disease it is, of course, beside our present purpose to enume- rate. X Ed. Med. and Surg. Journal, No. 109. § Ibid. Vol. 42. I 3 118 PRODUCTS, ADVENTITIOUS. § 5. DIPHTHERITIC DEPOSIT. The inflammatory action giving rise to the deposits which we inchide under the title Diphtheritic (AKpOep-q, a membrane), is cer- tainly of special kind, though the intimate nature of its peculiarity is yet undiscovered. These deposits form on the tegumentary sur- faces, mucous and cutaneous. (a.) White Thrush {Mugiiet of the French). — The matter of white thrush forms on the mucous membrane of the mouth, fauces, oeso- phagus, and nasal passages, in patches of milky colour, cheesy consistence, variable size, and irregular form. Adhering closely to the mucous surface when first exuded, it gradu- ally becomes more and more easily separable ; if artificially removed, the subjacent surface loDks slightly hollowed and somewhat raw, but is not abraded. The microscope exhibits molecules ; cells of oval, spherical, or elongated form, with or without nuclei ; epithelium cells, in more or less abundance ; and fibrils. These fibrils, almost transparent, of delicate and sharply- defined outline, of cylindrical form, gene- rally uniform in thickness, but sometimes swollen irregularly, and occasionally bifur- cated, are not affected by water, acetic or nitric acids, or alkalies, but dissolve in sul- phuric acid. Hence it appears obvious that this substance is in part entophytic ; but it is only secondarily so, — the rapid development of fungi depending on the constitutional state, or, perhaps, upon the chemical condition, of the local secretions. The smallest cells are pro- bably sporules. There is no structural difference between the matter existing in the white thrush of children, and that appearing on the mucous membrane of the mouth in adults towards the close of lingering chronic diseases, especially phthisis. But it has ap[)eared to us from numerous observations, that it is less prone to become entophytic. (6.) We have examined with some care the white material of cheesy consistence which forms, in certain states of the constitution, on blistered surfaces, kept open by irritant ointments, and find no particular difference between it f.nd the similar produce of mucous membrane. Entophytic formation occurs here. Obder II. — Growths. $ 1. Growths possess texture which differs in physical characters from all natural tissues, the arrangement of their septa and loculi being, among other things, distinctive of themselves. They differ, further, from natural structures, in a total deficiency of modelling faculty; they enlarge in all directions indiffer- ently, careless, as it were, of the mechanical mischiefs their presence may inflict. They are composed of evanescent vegetating cells, in- capable of propagation by artificial moculation into the tissues of the individual producing them. $ 2. The existence of structure in the order Growths is apparent on superficial in- spection. And there is one unfailing charac- teristic of this structure, as displayed to the naked eye ; it consists of a stroma and an in- terstitial matter occupying its meshes. This, which is the most striking peculiarity on the surface of some tumours (enchondroma, col- loid cancer), is much less evident in others (milt-hke variety of encephaloid, many spe- cimens of simple scirrhus) ; but in these latter it is clearly disclosed by slight maceration. And the want of a clear definition at first of stromal and interstitial parts depends, not on their non-existence, but on the more than ordinary similarity in physical characters of both. Generally speaking, in truth, there is a very obvious difference in this respect : the stroma of fully developed colloid has the aspect of cellulo-fibrous membrane, opaque and close ; its interstitial matter all the out- ward appearances of a jelly-like substance ; in enchondroma, the interstitial matter, resem- bling jelly of a different tint, is enclosed in a stroma, in many cases formed of laminae of bone. But, on the other hand, in some casts (as those referred to), there is no such obvious difference in the visible character of the two divisions, as they may be called, of the growth. In yet other cases, again, the outward cha- racters of the stromal and interstitial parts differ in colour, transparency, density, tenacity, when roughly examined, and yet their intimate constitution is almost identical ; this is the case in fibrous tumours. In the majority of Growths, the stromal substance encloses spaces inclining to the spherical form, a form most distinct in en- chondroma, colloid cancer, and fibrous tu- mours ; only imperfectly seen in encephaloid ; almost completely absent in simple scirrhus and in erectile growths. The manner in which the sphericity of the loculi is produced will be considered further on. Another element of Growths, which is vi- sible to the naked eye, or may be rendered so by means of injection, is blood-vessel. In varying proportions all Growths possess vessels, which may be limited to their stromal substance, or permeate both stromal and intrastromal substances. These vessels are in part those of the textures invaded by the new formation, in part adventitious pro- ducts. Lymphatic vessels and nerves are occa- sonally found within the area of a Growth ; but there is no evidence that they are ever of new formation. § 3. The ultimate essential elements of tumours are granules, molecules, cells, free nuclei, and fibrils. With these elements are accidentally associated Precipitates, Deposits, Exudation-Products, and certain of the sim- pler Pseudo- Tissues. (a.) The elementary granule is spherical in shape, flattened or amorphous; averages in size yo^ogth of an inch ; and is seated in the interior of cells, or on the surface of fibres, or is free. The molecule is too minute for mea- surement. (b.) Some portion of the substance of all PRODUCTS, ADVENTITIOUS. 119 Growths consist of hollow vesicular bodies or cells. The quantity of these cells varies extremely in different genera of Growths ; constituting the greater part of the mass of simple sarcoma and of enchondroma, abun- dant in colloid cancer, they are comparatively rare in scirrhus, and may be sought for in vain in the main substance of fibrous tumours. In form the cells of Growths are sphe- roidal, as in sarcoma ; or ovoid, as in enchon- droma ; and plump, or flattened, and discoid, in proportion to the abundance of their con- tents. In respect of size they vary within wide limits, from the simple fact that it is the nature of some to go on increasing in bulk (for instance, the cells of colloid and of en- chondroma), of others to retain persistently the dimensions originally acquired. This ana- tomical distinction is connected with a very important physiological difference in the mode of increase of Growths. We do not depart much from the truth in assigning 40^0 ■g^Q of an inch as the extreme measurements of these bodies. Further, the cells of the same Growth vary in size, independently of endogenous enlargement. Cells are either set beside each other, and cohere by their contiguous walls, or they re- main free. The thickness and transparency of the wall of cells vary ; the wall may be collapsed and corrugated, or stretched and smooth ; the nucleus (when this exists) of the cell may be distinctly parietal or not. The contents of cells are of four kinds : — fluid; granules; nuclei; young cells. Fluid, in more or less abundance, is constantly pre- sent in sound cells ; upon its amount mainly depends the plump or shrivelled aspect of these. Granules exist in abundance in the cells of sarcoma and of scirrhus. A free nucleus may be found sometimes in the cell of colloid cancer and of enchondroma. Young cr/e'c% fusiform shape. Our opinion on this point has of late grown much more decided. A shapelessly caudate cell, with irregularly curved fibrils, or lateral superadded fibril, is more closely allied to cancer, and will be described with that product. The accidental and non-essential elements of Growths belong to the other divisions of Adventitious Product. F rom the class Pre- cipitates may be found saline matter, amor- phous or crystalline, in minute quantity, or so abundant as to convert (in the instance of fibroma) portions of a Growth into true con- cretions. Fat occurs in the various forms mentioned in a previous page ; rare in some genera, as fibroma and enchondroma; it abounds in carcinoma. From the order De- posits appear melanic matter and pus ; the latter an element generated by inflammation in Growths as in natural textures. Growths, too, of one kind may (as entozoa of one species grow in the bodies of another) find a nidus for development in Growths of a dif- ferent kind ; cancer may thus appear wdthin the area of an erectile tumour. Exudation-Products exhibit themselves in the form of compound-granule corpuscles and induration-matter ; while of Pseudo-tissues, there occur epithelium, cartilage, cellular, seious, fibrous, elastic, osseous, cutaneous, pilous, and dental tissues; the last three limited to Cystoma. The elementary cells of Growths may either lie in juxtaposition, or interspaces, filled with so-called intcrcell substance, may 120 PRODUCTS, ADVENTITIOUS. exist between them. This substance may be fluid or sohd. Fluid intercell substance is nothing more than non-solidified bhistema; the solid variety is amorphous, or composed of fibrous pseudo-tissue. § 4. The Physiology of Growths com- prises the phenomena of their origin, en- largement, decay, elimination, cicatrization and local reproduction, — phenomena which, it appears to us, can, only by misapprehension of their true relations, be included under the head of the Pathology of these Formations. All that is known actually, or surmised upon fair grounds, concerning the oj^igin of Growths, has already been stated in our gene- ral remarks on Blastemal Formations. The enlargement of Growths is effected by the reception and evolution of nutritious matter. Growths receive this matter from vessels ; these vessels either permeate the mass generally, supply portions only of its substance, or merely reach a greater or less extent of its surface. In the first case, the growth is said to enlarge by intussusception ; in the third, by pure imbibition ; in the second, by both means. These distinctions are less important than they on first view seem ; the perfect nutrition of the extra- vascular natural tissues proves, as a general fact, the vigour and efficacy of the imbibition-process ; and in truth imbibition is at play in all nutritions, for the nutrient elements of vascular tissues must be imbibed through the coats of their vessels, and (it may be) in addition (as in the instance of the endosteal lining of the canals of Havers, and the subjacent osseous substance) through a stratum of cells. Enlargement by intussusception differs therefore from that by imbibition, in degree rather than in kind. In whichever way conveyed to the seat of Growth • formation, the nutrient material, at first fluid, is evolved and appropriated by continuous cell-generation. Now this cell-generation may be effected on an endogenous or an exo" genous plan. When the plan is endogenous, the germs of young cells are contained and evolved within elder ones ; these secondary cells are endovv^ed with a similar procreative faculty ; the tertiary series are in like manner fecund, and so on. Here a single cell may be regarded as the potential embryo of an entire growth. When, on the other hand, the plan is exogenous, the germs of new cells are not found within, but lie, and are evolved, outside old ones. Where endogenous evolution prevails, and a cell is, potentially considered, a tumour in futuro, the perpetual production of similar cells is easily intelligible ; the offspring that follows is as the parent that went before. But in exogenous Growths the continuous germination of infinite series of like cells is not readily conceived. It may be surmised (and the surmise amounts rather to a modified expression of the fact than an explanation), that when a series of cells has sprung into being, this series acts on the evolution of succeeding ones, as a natural vascularized surface is known to do on the generation of epithelium cells ; the formed series so in- fluences newly-exuded blastema (of which it constantly excites the accession), that this shall produce a new series of cells similar to itself. But, however the perpetuation of like cells be understood, be it remembered that the thing itself has its limits ; for, as we have just seen, deposits may appear in Growths, pseudo-tissues are among their fre- quent constituents, and a growth of one kind may establish itself a nidus within the area of another generically dissimilar. Elder cells thus seem (within certain limits) to cause the increase, and regulate the qualities, of younger ones. Younger cells are, on the other hand, more or less active agents in effecting the destruction of the elder ones : less so in endogenous Growths, where the elder may increase materially in size (as their contained brood multiplies), and acquire thickened walls ; more so in exogenous Growths, where such enlargement of cells is not witnessed, and where the production of young is coeval with the disintegration of old ones. Such are the modes of production and in- crease of cells, considered in their general relations to themselves and to the mass they form. We nuist now view cells as individual existences, and inquire into the process by which they are each developed ; and our knowledge of this process is as yet Hmited and unsettled. The spherical ceil appears to be produced on three distinct plans. («.) Gra- nular matter, precipitated from the fluid blastema, accumulates sufficiently to form a minute solid body (cytoblast or nucleus), from and around which the cell-wall forms. ((6.) The cell is a molecular hollow body from the first, and, as it grows, produces within itself, or in its wall, a secondary body, the nucleus, — the cytoblast of a future cell, (c.) The cell is, from the first moment of its existence, complete in all its parts, consisting of a cell-wall, a nucleus, and fluid contents ; its development consists in the progressive and justl3-proportioned increase of all these elements. The caudate cell is held to arise (as already hinted) from the prolongation of opposite points of the wall of a spherical cell ; but there is no proof that cells may not exhibit this shape from the first moment they are possessed of form at all. Lastly, the ele- mentary fibre is held to be formed in three different modes, (a.) A spherical cell having undergone elongation so as to become cau- date, loses by still increased elongation and flattening, the characters of a hollow cell altogether ; a nucleated fibre is the result. ib.) Elongation and linear juxtaposition of nuclei effect the formation of fibre, (c.) Or, it is held, fibres form as such from the first moment shape is assumed ; no cell, or nucleus-stage having pre-existed. All these points are yet subjudice. The plan of enlargement and mode of arrangement of the ultimate elements of PRODUCTS, ADVENTITIOUS. 121 Growths seem to exercise a very distinct in- fluence on the structural character of the mass as visible to the naked eye. The locular aspect of their divided surfaces, for instance, we fully believe to be dependent on such influence. In the case of Growths enlarging on the endogenous plan, it is obvious that the juxtaposition of successive round cells within a containing or parent cell must cause this to retain its spherical outline, until it has en- larged sufficiently to become visible with the naked eye ; and further, that if several of these enlarged ceils be placed round a common centre and beside each other, the general form of the area they cover must be spherical. And so we find that it is precisely in enchon- droma and in colloid cancer, distinctly en- dogenous formations, that sphericity is most decided. The thickening and fibrous depo- sition, which take place both in the walls of enlarged cells and in the interceli substance, contribute further to the deceptive appear- ance of encysted structure. In masses which enlarge on the exogenous plan, the spherical character in the loculi is much less apparent. In scirrhus, and in many specimens of ence- phaloid, it is not to be clearly descried ; the pre- dominance of straightly-fibrous arrangement of the stroma, produced by the presence of real fibrous tissue, of fusiform corpuscles, &c., accounts for this. But even in Growths of this class, the original rounded form of the elementary constituents tends to impress upon their larger divisions, as these do upon the entire mass, the spherical shape. Accidental circumstances, of course, are liable to affect this ; but the internal locular arrangement of fibrous tumours shows that those circum- stances may be only partially effectual. The locular character (under the title of "encysted") has been put forward as an evidence of "malignity" on the part of the structure exhibiting it. Experience proves the notion to be untenable. Sphericity of the loculi is most obvious in enchondroma, one of the most intrinsically innocent Growths known ; such sphericity is, on the other hand, totally, or almost totally, wanting in scirrhus and many specimens of encephaloid. Again, the least deleterious form of cancer — col- loid, exhibits it in an especial manner; and, though modified, it is evident in those pecu- liarly benignant structures (considered in their essence) fibrous tumours. The decay of Growths is preceded by soften- ing of their substance ; this softening, indeed, by its increase actually constitutes their de- cay. The change is effected by infiltration of serosity, interstitial haemorrhage, by satura- tion with inflammation-products and by gan- grene, either of inflammatory or simply mechanical origin. Or, there is an important class of cases, in which the softening of Growths seems analagous to that undergone by stagnating fibrin, and probably depends on chemical decomposition. The removal of Growths (fibrous, cancerous, and others,) is sometimes effected by a spon- taneous process, commonly comprising at- tenuation and rupture, or ulceration of the investing natural tissues, and gradual liquefac- tion of the morbid matter, which is poured through the opening ; or, in less common cases, consisting of sphacelus, whereby the mass, in whole or in part, is separated from its connections. Cicatrisatioyi of the ulcerated surfaces of Growths is occasionally witnessed. We have ourselves seen this change occur on the proper surface of formations possessing all the cha- racters of scirrhus. Growths of all descriptions are liable, when removed spontaneously or by art, to be repro- duced in the spot they previously occupied, if the removal have not been absolutely com- plete. The particles left behind act as at- tractive forces for new blastema convertible into cells, similar to those of which themselves are composed. This mode of reproduction (as it is erroneously called, for it is nothing more than enlargement, facilitated by removal of pressure of pre-existing substance) occurs with Growths of all kinds, cancerous, sarcoma- tous, fibrous, fatty, enchondromatous, erect- ile, &c. But it would appear that in some cases of surgical removal, when the whole mass has, as is presumed, been extirpated, a new growth vegetates in its place. The dif- ference of the cases is often rather apparent than real : we have distinctly found the ger- mina of cancer in tissue, reputed healthy, surrounding a cancerous mass ; and it is manifest that such germina, though invisible to the naked eye, ma}^ quite as readily as a fragment of diseased tissue of even consider- able size, act as the efficient agents of new development. When, independently of this mode of generation, the disease returns in the seat of its former growth, the occurrence must depend upon the continuance of that depraved state of the blood which is fitted to supply the necessary blastema, and likewise, possibly, upon some peculiar state of vessels of the part favouring its exudation liere rather than elsewhere. o i\y ^ ""^-^ In other cases, hardly has^^-gi^Qwth been removed from one place, when a mass of the same kind appears in some distant and appa- rently unconnected part of the body : this occurrence, which is especial!}'" observed in the case of cancer, is termed its " distant repro- duction," and is explicable in two ways. The newly discovered growth may have existed previously to the extirpation of the old one, and having simply acquired additional activity, so become obvious, after that extirpation. Or the new growth may really have first appeared subsequently to the removal of the old (this we believe to be rare) : in this case the simple explanation is that the vitiated state of the blood, proper for the supply of the neces- sary blastema, continues ; and this blastema is poured out in some other part of the frame, the original tumour no longer existing to attract its deposition within or around itself. § 5. The chemical study of Growths is yet in its infancy. Miiller's division into three chemi- cal classes, the albuminous, the gelatinous, and 122 PRODUCTS, ADVENTITIOUS. the fattv (rational enough, chemically con- sidered,) fails pathologically. Growths of very opposite tendencies and attributes are to be found in the same chemical class ; thus the most deleterious forms of cancer are albu- minous, while sarcoma (per se most innocent) is the same in its chemical basis. (a.) In the albuminous growth the other forms of protein are frequently present as essential ingredients ; the term growth of protein-basis appears therefore more strictly applicable, A matter said to be alhed to ptyalin has been found in this class. Con- tinued ebullition scarcely furnishes a trace of gelatin ; and when some such trace does appear, is probably derived from natural gelatinous textures accidentally connected with the morbid mass. (6.) Growths of the gelatinous class are almost completely reduced to jelly by boiling. The gelatin yielded is either of the common species, as in fibroma, or of the variety known as chondrin, and first detected by Muller in enchondroma. (c.) In the fatty class, the fatty matter is chemically the same as that of ordinary adipose tissue (e. g. in lipoma); or it is more or less closely allied to cholesterin (e. g. in cholesteatoma). The fattv particles which exist in almost all Growth's, even of the albuminous kind, and which do not form the essential part of the mass, are not contained in cells, as in true fatty Growths, but exist in the various forms enumerated in a former passage. Carbonates, hydrochlorates, and phosphates of the alkalies and earths are the inorganic salts most commonly and largely associated with the animal constituents of growth. § 6. The Pathology of Growths em- braces the subjects, first, of the morbid changes arising in, or in immediate connection with, thoselformations ; and, secondly, of the va- rious conditions of the system which precede, accompany, and follow their evolution. Their pathologv may, in other words, be regarded as local and general. {a.) Local — Under the head of physiology we have considered briefly the various changes arising in Growths, as essential phenomena of their '^complete development ; and which, however they may be regarded as morbid in respect of the system generally, are, on the part of the adventitious mass in which they take place, evidences of natural progress. But there are numerous changes occasionally occurring in Growths, that are actually morbid in essence in relation to the substance of the new product itself; and others of a similar character which are produced in the sur- roundmg tissues. These two classes of changes (which can only be glanced at here) consfitute the materials of the Local Patho- logv of Growths. 1". The changes observable in the substance of Growths, and which signity a departure from the regular process of evolution, are : — congestion ; infiltration with blood or with serosity ; haemorrhage, and in consequence of these states, various forms of discolouration; inflammation ; mortification ; and the deposi- tion within or upon them of some adventitious material foreign to their nature. In fact, the chief morbid changes occurring in the natural structures may arise in these formations. 2. The effects produced by Growths on surrounding tissues are mechanical and vital. The mechanical variety comprises detrusion and various other displacements; condensa- tion ; discolouration ; infiltration ; blocking up of cavities ; interterence with the motion of fluids, Sec. The detrusion produced by Growths may be simple, expansive, or causing peduncu'a- tion, a peculiarity observed when certain Growths, endued with little or no tendency to infiltrate the parts around, originate be- tween a mucous or serous surface, and a hard, resisting tissue. And this for ob\-ious reasons; with the progress of their enlargement the distention they induce does not equably affect all surrounding parts (because the re- sistance of these is unequal), but acts espe- cially upon the least resisting structures. As they enlarge, they carry these structures be- fore them, until themselves eventually pro- trude sufficiently from their precise seat of origin to leave a sort of process of the mem- brane they push before them, acting as a stalk of attachment to the place of their original connection. A growth thus pedunculated is practically known as a Poli/pus, a term extremely injudi- cious, as it leads the observer to neglect the important matter of the nature of the tumour, and to regard a mere accident of shape as an essential feature. The vital effects are rarefaction ; condensa- tion ; atrophy ; hypertrophy ; inflammation, with its results — aahesion, softening, indura- tion, ulceration, mortification, perforation, effusion of blood, enlargement of vessels, &:c.; and, most important of ail, infiltration of the surrounding tissues with matter similar to that composing the new growth. This last effect occurs (as we believe) in connection w ith no growth except cancer, and constituting one of the most evident pathological and nosological distinctions between cancerous and other allied formations, will be presently examined. § 7. The nature of this work will not admit of any extended observations on the general Pathology of Growths, but some prominent facts can scarcely be passed over in silence. The conditions of localization of Growths are curious, and for the most part inexplicable. The following propositions may be laid down concerning them : — {a.) The tendency to become the seat of Growths, as a class, varies greatly in the dif- ferent tissues and organs. Thus, while cel- lular tissue is their peculiarly favourite site, fibrous texture but rarely affords them a nidus. Again, the mamma, the ovary, the uterus, are frequent, the lungs and brain much less common, sufferers. {b.) The tendency to become the seat of PRODUCTS, ADVENTITIOUS. 123 Growths, as a class, varies in the difFerent parts of organs. Thus the pyloric end of the stomach suffers more frequently than the rest of the organ ; the epididymis than the hody of the testis. (c.) Certain organs, and certain parts of organs, have an excess of tendency to the formation of certain special Growths. Thus the uterus, the mamma, the stomach, the liver, are peculiarly prone to cancerous, as distinguished from other forms of growth ; the bones are the chosen seat of enchondroma. And, again, cancer does not form indifferently in all parts of the uterus, but tends especially to invade its neck ; while fibrous tumours affect a preference for the body of the organ. The large intestine is a tolerably common seat of cancer ; the small is very rarely implicated. (d.) Growths of different kinds exhibit dif- ferent degrees of compatibility as co-existences in the same body. Some Growths, as Cystoma and Carcinoma, are sufficiently prone to appear in the same individual; others, as Fibroma and Carcinoma, are rare co-exist- ences ; none are actually incompatible, either as unconnected co-existences, or as develop- ments in each other.* Sex influences the site of Growths. The renal organs of the male suffer more fre- quently than those of the female ; the con- verse is true of the genital organs. In like manner, age has its influence. But on the whole, the causes of these peculiarities of seat are unfathomed. A Growth having once been developed, may pursue an anatomical (or better, topo- graphical) course, of three different kinds. First, it may remain solitary and alone till the death of the individual in whom it exists, no other organ or tissue than that originally af- fected becoming involved by similar disease. This is frequently observed in the case of enchondroma and of cystoid tumours, occa- sionally of fibrous, and even of cancerous Growths. Or, secondly, a morbid mass originates in some particular site, whence it seems to spread as from a centre to a multitude of parts ; the latter are said to be the subject of secondary Growths. The mechanism of this propagation differs according as parts adjacent to or dis- tant from the primary formation are the con- secutive sufferers. (1.) When circumjacent tissues become the seat of secondary develop- ment, this is either the result : — first, of pro- * It is true we have never ourselves seen cancer within the substance of a fibrous tumour ; but there is no a priori motive for disbelieving the possibility of such localization, and competent persons affirra they have seen examples of it. Although tubercle is not, properly speaking, a growth, it may be well to observe here (as we first showed eight years ago), that this product and cancer rarely co-exist. Among 104 cases of death from cancer, there were but seven in which the anatomical character of phthisis was present. The age at which the two diseases are most prevalent will, to some extent, but not wholly, explain this result. (See Nat. and Treatment of Cancer, p. 185.) On the other hand, the diseases by no means absolutely exclude each other ; cancer and tubercle may form in the same organ. gressive and direct infiltration of those tissues by the morbid matter; or next, of infiltration spreading to those tissues through the me- dium of the proceeds of common inflam- mation (induration -matter) previously depo- sited among them, in some instances effecting adhesions between parts not actually adherent to each other in the natural state ; or, lastly, possibly of infiltration arising in some unex- plained way, through the influence of a part simply placed in juxtaposition, and not con- tinuous (either naturally or accidentally) with the tissues primarily affected. These modes of secondary implication are exemplified by cancer alone. (2.) The formation of second- ary Growths in distant organs, where an effect of pre-existing disease elsewhere, seems only intelligible as a result of transmission by the lymphatic or vascular systems. Cancerous, and perhaps fibrous tumours, give rise through both these routes, to secondary development. As respects the lymphatic glands in commu- nication with a cancerous mass, they may themselves become cancerous, while the ves- sels leading to them are either filled with morbid matter of the same kind, or perfectly free from all anatomical change. Now when the tubes are themselves loaded with cancer- ous substance, and are, for example, traceable so loaded even to the thoracic duct (A. Cooper ; Hourmann), without any evidence existing of the matter being a product of their own tissue, the implication of the lymphatic system, is evidently the result of absorption. But when (as is more commonly the fact) the cancerous state of the glands is unasso- ciated with similar contamination of the con- necting tubes, it is not thus so plainly and sa- tisfactorily explicable. Still it is probable that in the majority of cases the principle is even here the same ; but that the mode in which stagnation of absorbed particles takes place differs. In other instances it is possible that cancerous development in the glands may be effected as in an independent and original centre of production, and not through a pro- cess of absorption or other direct mode cf influence of pre-existing Growths. These no- tions are put hypothetically ; but they appear to me more likely to be well founded than those usually tendered. Nevertheless if contamina- tion be admitted to arise as a result of absorp- tion in some instances, the inference appears necessary, that it shall occur in all cases ; inas- much as a process of nutrition, accomplished in the usual way, is constantly going forward in morbid Growths. Now, as matter of fact, such contamination does not always ensue, and, above all, does not commence from the earliest period of evolution of the previous growth. Here seems to lie a serious objection to the doctrine of lymphatic absorption. But the absorption is only thus shown to be of a kind which w^e may, for convenience sake, call un'productive ; and which may be assimilated to that taking place from abscesses, in cases where no pus, with its sum of natural proper- ties, finds its way into the circulation. That the pus-corpuscles undergo, in such cases, dis- 124 PRODUCTS, ADVENTITIOUS. integration and alteration, is matter of physical demonstration — changes which divest them apparently of their pathological properties. On analogy, which seems in nowise strained, we may then admit that disintegration of the elementary ceils of the morbid Growth is the cause of the occasionally n7i])rodiiciive cha- racter of cancerous absorption.* When, on the other hand, secondary Growths form in locahties free from direct lymphatic commu- nication with the seat of the primary forma- tion, there can be no doubt (although the productive elements have not yet been found in transitu with the circulating blood) that the venous system acts as the agent of trans- lation of such elements from the one to the other site. In the instance of cancer the following arguments may be adduced in favour of this notion, a. " Cancerous matter exists in a multitude of cases in the veins of the diseased part ; now this is obviously a most favourable circumstance for its circulation with the re- turning blood. j3. The rapidity of the suc- cessive development of the disease in different organs, sometimes observed, seems only pro- ducible by the agency of a fluid which, like the blood, pervades them all. 7. The liver and lung, the two organs in which foreign bodies introduced into the circulation are almost invariably observed to stagnate, are by far the most frequent seats of the secondary development of carcinoma. 8. The parenchy- matous viscera and the bones, the precise structures most frequently affected with se- condary abscess, are those peculiarly liable to secondary cancer, e. In respect of both mor- bid products, the liver and lungs stand at the head of the Hst for frequency of implication. ^. Secondary abscesses affect a special pre- ference for the peripheric strata of the viscera ; so likewise do secondary cancers. In the instance of the lung, I believe this readily explicable, by the fact that the majority of the ultimate ramifications of the pulmonary artery reach the periphery of the organ before be- coming continuous with the capillaries, where- in stagnation must occur. 77. Double organs are very rarely the simultaneous seats of pri- mary abscess ; in cases of secondary abscess both invariably suffer : the same propositions hold good of cancer. ^. Secondary cancer in the liver and lung occupies the same ele- mentary seat (the lobules) as the pus of * Absorption of cancerous matter artificially in- duced, woidd apriori appear likely to prove of the unproductive kind, as disintegration of the primary particles of the growth must, in all probability, form a stage of the absorptive process. The question is rendered one of practical interest by the prospect held out of removing these tumours by the ingenious system of pressure invented by Dr. Arnott. It is clear, in truth, that if that system only lead to the translation, from one part of the frame to another, of elements endowed with the faculty of unlimited germination, the benefit obtainable from it is more apparent than real. AMiereas if, while that system causes their entry into the circulating fluids, it deprives their elements of all productive power, and leaves them in a condition fit for excretion as efifete particles, a ])erfect cure of the disease is ef- fected by the removal of the tumour. secondary abscesses."* Some apparent ob- jections to the doctrine here upheld are ex- amined and (as we believe) refuted in the same place. Or, thirdly, in certain cases where numerous parts are found to be the seats of tumours of the same species, it is more than probable that the development of these tumours has been simultaneous, and each mass been evolved independently of its fellows. There can be no doubt, for instance, that internal cancer is frequently described as secondary to external cancer (especially when the latter has been removed with the knife, and the former has not manifested its existence by symptoms until after the operation), where no proof of the two Growths not having originated at the same time can possibly be adduced. The same is true of Fibrous Growths. The inoculabiliti/ of Growths has not been maintained except in the instance of cancer, and, even in respect of this product, upon very imperfect evidence. Experimental re- sults may be cited against (Dupuytren), and in favour of (Langenbeck),the transmissibility of the disease by inoculation ; while, on the other hand, we learn from M. Gluge that his attempts generally failed utterly, and in rare cases appeared to succeed. Theoretical con- siderations, repudiating, as they do, the idea of the constant inoculability of cancer-ele- ments in organisms of all varieties of morbid aptitude, nevertheless do not wholly oppose the notion, that where constitutional predispo- sitio?i to cancer exists in an animal, the ger- minal element of that product, introduced into its blood, may prove prolific. Unless this constitutional state exist, "even the ac- tual elements of cancer only manifest them- selves as simply irritative agents, the perfection of the seed is not enough to secure the de- velopment of the plant; the soil, in which it is sown, must be capable of feeding it." Per- haps these views furnish a clue to the con- tradictory statements of experimentalists. § 8. Clinical observers of disease have long been aware that certain Growths are of evil, others of innocent, tendency ; that they are " malignant" and " benignant." Morbid ana- tomists have sought to connect definite and invariable structural characters with the pos- session of one or the other tendency ; and their search has been vain. Micrologists are divided on this question ; some affirm that "malignancy" depends on the presence of a special cell ; others deny the distinctiveness of microscopical elements. We, for our own parts, believe that the qualities of a growth cannot be determined by the characters of its cell. We have known Growths, which had destroyed life with the cachexia of cancerous disease, and clearly exhibited the local progress and naked-eye characteristics of encephaloid; Growths which, nevertheless, were composed of non-nucle- ated cells undistinguishable from those of common exudation-matter. Nor do we be- * Nat. and Treatment of Cancer, p. 106. PRODUCTS, ADVENTITIOUS. 125 lieve that, any mode of association of cell and fibril (at least any mode now known and un- derstood) can be considered distinctive of carcinoma. On the other hand, we believe that Growths of evil tendency have a manner peculiar to themselves (ascertainable by naked-eye observation) of accumulating in the tissues. We refer to accumulation by hifiltration. The nature of infiltration is easily explained. The elementary molecules of the morbid matter, instead of accumulating round a central point equally in all directions, and pushing aside the tissues amid which they are deposited, spread between the primary ele- ments of those tissues on every side. In proportion as this extension of the morbid matter is accomplished, interference with the healthy process of nutrition takes place. The elfete particles of the natural tissues cease to be replaced by similar ones ; and an appearance of conversion (" transformation " or "degeneration") of a natural into a mor- bid structure is worked out. But if the nature of the phenomenon be simple, its cause is obscure. Why it should occur (as we conceive it does) in the instance of cancer alone, and why peculiarities so important as those of cancer, in respect of general influence on the system, should appear to hat)g upon the existence of a local pathological attribute, in nowise remarkable, strictly considered ^j//y5io/ogica//y erectile, have been 128 PRODUCTS, ADVENTITIOUS. presumed to be anatomically so, and con- founded with Growths composed of true erec- tile tissue. Allied, at least in its functional characters, to angeiectoma, is the growth composed of true erectile (or cavernous) tissue. Soft, doughy, pseudo-fluctuating, pulsatile, erectile, the occasional seat of tactile fremitus and blowing murmur, occurring generally in a single, but sometimes in many spots, com- monly cutaneous or sub-cutaneous, but liable to grow in deep-seated parts, congenital or accidental, rarely exceeding a Seville orange in size, and often very small, traceable in rare cases to the influence of pressure or other external injury; sometimes of rapid, oftener of very slow progress ; the true erectile tu- mour has a structure perfectly assimilable to that of cavernous tissue, and, like this, a structure not yet thoroughly unravelled. On section these growths {fig. 94) exhibit Fig. 94. Section of a true erectile growth, (t' C. JIus.) on a coarse scale the interlaced columnar appearance of erectile tissue : the trabeculae vary in thickness and density, and are pro- vided with minute vessels ; the hollow spaces between these are shallow or deep, narrow or broad, quadrangular or triangular, and com- municate with each other. Microscopically the trabeculte are found to be composed of fasciculated, cellular or fibrous (in very rare instances of intermingled elastic) fibrils, coated with tesselated epithelium, which conse- quently also lines the hollow interspaces. When these trabeculse are in process of growth they contain fusiform cells. Such Growths are never encysted, but they sometimes acquire a secondary capsule of condensed cellulo-fibrous membrane. It is said they are sometimes lobulated, a condition in which we have never seen them. They are rapidly regenerated if imperfectly removed. Particularly when connected with the skin, erectile structures may become the seat of cancerous formation. Erectile Grow ths generally appear in super- ficial parts, the skin and subjacent cellular membrane ; the mucous membrane of the anus (as a rare variety of pile) ; the gingival membrane (?) ; the tongue (Brown, in Lancet, 1833). Mr. Listen (Med. Chir. Trans, vol. xxvi.) describes an erectile tumour (Univ. Coll. Mus.) seated in the substance of the semi-tendinosus muscle; Andral (An. Path. i. p. 463) speaks as if the structure were not uncommon in the intestines, — but we have never seen it here; Lobstein describes it in the liver (?) ; Rayer (Maladies des Reins, t. iii. p. 612) in the kidney. § 5. 31ELAX0MA. .Melanic cell-pigment, as described in a pre- vious page (p. 116), may be deposited in the substance of various Adventitious Formations, — of Deposits (e. g. Tubercle), of Growths (e. g. Cancer), and of Pseudo-Tissues (e.g. Os- siform structure). Grow ths, more or less deeply tinged by its presence, have been distinguished as a special class of products under the titla of jNIelanotic Tumours or Melanomata. Whe- ther they have any real claim to such distinc- tion will be best argued, when we have, in as few words as possible, glanced at the struc- tural characters of Tumours of black colour. These tumours are, in some instances, sar- comatous, in others composed mainly of en- larged vessels, in others cystomatous, in others fibrous, — the pigment being deposited be- tween or within the convoluted fibres or ves- sels of the mass. But no growth contains melanic pigment so frequently as cancer. Studded in points through the cancerous masses, accumulated in lumps or equably in- filtrated through their substance, the cell- pigment gives them a peculiar dark colour. This discolouration is by far the most common in the encephaloid species, and occurs most frequently in cancer of the eye, skin, and liver, but is not peculiar to any locality.* Misled by the frequency of this discoloura- tion of cancerous tumours, various writers have endeavoured to rank "Melanosis" generally as a cancerous disease. Lorinser, Laennec, Dupuytren, Alibert, Meckel, vonWalther, and Cruveilhier, for instance, take this view of its nature ; and more recently Miiller has de- scribed " carcmoma melanodes" as one of his six species of cancer, holding as distinct and individualized a place in the class as Ence- phaloid or Scirrhus. The following reasons lead us to dissent altogether from these doc- trines. (1.) That melanic pigment should in itself constitute cancer is an impossibility ; it never even forms a stroma, as the cells con- tinue permanently free. (2.) The stroma of many melanic tumours (as of those above referred to, fibrous. Sec.) is perfectly distinct in its physical and chemical characters from all cancerous stromata. (3.) The microsco- pical characters of the pigment-cells and gra- nules are the same in tumours of cancerous nature and in non-cancerous growths. (4.) Melanic tumours, when free from acknow- ledged cancerous elements, cause no special, local, or general symptoms. (5.) When me- lanic tumours give rise to the symptoms of cancerous disease, their solid stroma is found to be composed in whole or in part of ence- phaloid, scirrhus, or colloid. (6.) Neither the local nor general symptoms of cancers are * The Univ. Coll. Museum contains a model of melanotic encephaloid of the vertebrae and spinal meninges. PRODUCTS, ADVENTITIOUS. 129 modified by the presence of cell-pigment within them. (7.) "Melanotic tumours" are rarely solitary, it is urged by Cruveilhier ; but this simply depends on the fact of ence- phaloid cancer being the growth most fre- quently impregnated with black pigment. The stromata above referred to are the only kinds which we have ourselves seen or known of as elements of black coloured tumours in the human subject. But in the horse a species of melanic mass of different constitution is frequently met with ; and may, for aught we know to the contrary, occur (if so, probably only in rare instances,) in the human subject. These masses are of lobulated form, per-, fectly and deeply black in colour, sometimes attain great bulk, and feel remarkably elastic and spongy. Of the numerous specimens of the kind in University College Museum, an attemj)t has been made to inject one with a white material ; a few spots of v/hite colour in the substance of the tumour alone give evi- dence of the attempt ; no trace of vascular arrangement is perceptible. A portion of the mass having been allowed to macerate in chlorine water for four days, the colour was rendered sufficiently faint for observation of the stroma. It consisted of deUcate fibrils (gelatinizing with acetic acid) arranged parallel to each other, without the least appearance of meshes. The pigment-granules, which were not contained within cells, (at least, no cells wei"e visible), lay upon the surface of the fibres in some' places, so as on first sight to give an appearance of cross lines ; in others they lay between the fibres. The conviction arises that this tumour may have been a haematoma; absolute proof is, we admit, yet wanting : if we are right, it would follow that the only doubtful kind of black tumour we have seen, possesses in reality, like all others, a stroma of ascertained nature,, with black pigment added. And the observation lends indirect support to the view (still unesta- blibhed) of those who presume black pigment to be, under all circumstances, formed from the colouring matter of the blood.. Of Fat-Basis.. Growths of fat-basis agree in not being properly encysted, though they may occasion- ally acquire a secondary capsule from con- densation of adjacent cellular membrane. The chief species are Lipoma, Steatoma, and Cholesteatoma.. § 1. LIPOMA^ Lipoma is a growth of softish consistence, somewhat elastic in form, generally dis[)osed to be globular, though occasionally distmctly flattened ; frequently lobulated, and furrowed on the surface ; varying in size from very minute to vast dimensions, weighing from a few grains to ten, twenty, or (if records be true) forty pounds; ordinarily single, espe- cially when of notable bulk : — iwo or three of the size of the clenched hand may, however, not unoften be seen together ; and occasion- VOL. IV. ally, when of very small size, considerable numbers coexist in the same individual. Lipoma most commonly forms in the sub- cutaneous adipose texture (where it partakes of the characters of hypertrophy )> but appears to be producible wherever cellular tissue exists. MUUer has seen a lipoma between the corpora albicantia and optic nerve ; Albers {Palhologie, b. ii. s. 189),, found a lipoma of the size of a mushroom betw een the arachnoid and dura mater,, on the level of the fourth lumbar vertebra ; Andral {A7iat. Path. ii. 412) describes one as large as a walnut, seated in the walls of the vena porta?. Growing between the peritoneum and abdominal wall, lipoma sometimes escapes by the abdominal rings, and constitutes the so-called " fatty hernia." In a fatal case of infiltrated cancer of the right lung, which lately occurred in our wards (Univ. Coll. Hosp.) a lipomatous mass had formed in the pleura of the affected side. Lipoma on section, and even externally, presents the appearance and possesses the physico-chemical properties of common adi- pose tissue. The fatty elements, (margarin and olein) are removable with boiling aether. Microscopically the fat is found to be con- tained in cells, of the natural size, aggregated in parcels amid and upon the fibres of a" deli- cate cellular tissue ; the dimensions of the mass have no influence on its intimate con- stitution. The cells commonly of rounded shape, become much more rarely polyedrai from lateral pressure, and are for the most part non-nucleated. Their contained fat is fluid at the tempera- ture of the body : when cool, separation of the olein and margarin takes place (as shown by Messrs. Todd and Bowman in the case of natural fat) and star-hke groups of crystals of the latter form in the interior of the cell. We have occasionally seen free oil globules in lipoma, but whether arising from accidental rupture^f containing cells or not, we cannot determine. The vessels of lipoma are of small size, and ramify in its stroma. A delicate laminar cellular membrane in- vests the majority of lippmata ; infiltration of texture is never effected, by these growths. Their cellular investment may become fibrous, giving them a pseudo-encysted character. Pedunculation (single or multiple) is not un- common ; the peduncle sometimes stretching away to some distance from the main part of the growth ; from the front of the sternum, for instance, deeply into the mediaotinum. The natural course of lipomata is to increase almost indefinitely in bulk, without giving rise to any other inconvenience than that arising from their size, weight, and position. The surrounding skin bears without ill results an extraordinary amount of distension ; though eventually attenuation, low inflammation and gangrene have sometimes ensued. Lipomata are susceptible of inflanunalory softening, (a rare occurrence however) leading to break- ing down of their substance ; the physical, and probably chemical qualities, of the fat change materially. Growths thus altered have K 130 PRODUCTS, ADVENTITIOUS. *' become cancerous," in the erroneous lan- guage of their describers ; v>e have never seen or read of a satisfactory example of cancerous formation, from a basis of lipoma. Fibrous thickening of the cellular septa of the growth is not uncommon ; but a true fibroma is never evolved from a lipomatous tumour. Absorption of the fat may be effected by arti- ficial pressure ; the residual cellulo-fibrous structure forms a more or less dense mass. Lipoma with excess of cellulo-fibrous stro- ma, much firmer than the simple variety, and more frequently invested by a pseudo-cyst, has been described under the names of Adipose Sarcoma, and Lipoma Mixture. Lipoma has sometimes a semi-transparent almost gelatiniform look, the cause of which is not clear. Mliller proposes the title of lipoma arbores- cens for certain rare adipose formations, found in the joints. They originate behind the free part of the synovial membrane, pro- trude into the joint, and form tufts, nodulous at the ends. They are said to be most com- mon in the knee-joint. Tiie pleural lipoma, just referred to as having occurred in our own practice, might be accredited to this variety. § 2. STEATOMA. There is a variety of fatty growth of greater density and solidity than lipoma, close in grain, inelastic, opaque, having the aspect of suet or sometimes of putty, wholly unlike natural adipose tissue. Such tumours, to which the name of steatoma is given, are composed of fat, soluble in boiling alcohol, non-vesicular, granular, and amorphous, and aggregated into masses without the interven- tion of cellular tissue. These accumulations sometimes acquire great bulk ; we have seen them in the mesentery, testicle, and mediasti- num. § 3. CHOLESTEATOMAi^^J^^X^ See Cholesteric Fats (p. 94), Of Gelatin Basis § i. fibroma. Fibrous Growths appear naturally to affect the spherical form : they may, however, be accidentally flattened (as in the walls of the uterus, during the advance of pregnancy, Univ. Coll. Mus.) ; pedunculated (seep. 122) under the mucous membrane of the nose and uterus ; or nodulated from having two or more centres of development. They may be smaller than a pea (in the dura-mater for instance); or, especially w^hen developed under the peri- toneal coat of the uterus, exceed the head of an adult in size : tumours of this kind have been known to weigh 25, 30, 35, and 39 pounds. Their external surface is naturally smooth and even ; loose filaments of cellulo- vascular tissue form their common material of union with adjoining textures ; in some cases the connection is rendered unusually intimate by exudation-matter. (See p. 125.) On section the colour of these grow ths is generally found to be greyish-white, — thegrey- ish colour being thatof the intrastromal matter, the white (which may be dull or ghstenini:) that of the stromal. Less commonly fibroma has a reddish hue. The consistence of the mass varies with its colour : the greater the white- ness, the greater the density, specific gravity and tenacity of the tumour ; the reddish coloured growth is comparatively soft and yielding. The constituents of fibrous tumours visible with the naked eye, are white bands ; a ma- terial interposed between them of darker colour, less opaque, less dense, and less manifestly fibrous ; and, in comparatively rare cases, vessels, — congregated in the main to- wards the peripliery of the mass. The arrange- ment of the white bands and of the enclosed darker substance is peculiar: the bands follow an irregularly curvilinear direction ; the loculi hence affect the spheroidal or oval shape. This character helps to distinguish fibroma from scirrhus with great excess of fibrous stro- ma; in such scirrhi the fibres always exhibit a tendency to rectilinear arrangement. By firm pressure a transj)arent, pale straw coloiu-ed (never lactescent), and glutinous fluid may be forced from a fibrous tumour : its quantity is very small, and it may be infiltrated through the growth or accumulated in spots. Microscopically these growths are found to consist of fasciculated and intertwined fibres, less undulating in direction and less clear in outline than those of natural fibrous tissue, arranged parallel to each other, and studded or not with minute inequalities, produced by the still remaining nuclei of original cells. In the soft fibrous tumour this filamentous ele- ment is the same in character as in the hard ; but it is less abundant, less closely set, and scarcely fasciculated : in this variety, too, it is more common than in the hard, to find cells with granular contents, some of them assuming the fusiform shape. We have oc- casionally seen fat-granules in these tumours ; but fat is never one of their predominant ele- ments. When submitted to ebullition, the entire mass of a fibrous growth is converted into a jelly (glutin), w ith the exception of a very minute quantity of protein substance, derived, pro- bably, f rom associated blood : the walls of the few cells, such tumours contain, are insuffi- cient to account even for that minute quan- tity. Their saline constituents are, in various proportions, those of the blood. Valentin attempts to show that fibrous tumours of the uterus are sometimes coniposed of fibrin: doubtless, as we have already explained (p. 126) hasmatomata of the uterus occur, and may undergo evolution into fibrous tumours: but we altogether discredit the alleged fact, that tumours exhibiting the microscopical constitution of fibroma, are ever of protein- basis. The nature of fibroma leads it simply to enlarge, without change in, or around, itself. Some alterations of texture are so common, PRODUCTS, yVDVENTITIOUS. 131 however, (the so-called cartilaginification and ossification) as to have passed for phases of evokition of fibroma; others (congestion, in- flammation, serous infiltration, haemorrhage, deposit of melanic matter, precipitation of fat, great development of vessels, and cancer- ous formation,) are, on all hands, confessedly morbid. Patches, more or less extensive, and having the outward appearance of cartilage, are of common occurrence in fibrous tumours. The period at which this change occurs is inde- terminate; nor has the size of the growth any appreciable influence upon it. We have examined some specimens of this kind with- out detecting any cartilage corpuscles, and incline to regard the outward change as simply signifying an increase of density and closeness of deposition of fibres. Nor is the alleged " ossification " of these tumours, according to our observation, more real. We have not succeeded in detecting in the ossified-looking parts either the cor- puscle or the laminated structure of bone, but simply saline particles or granules closely or loosely set in the organic basis of the tumour : actual ossification has, however, sometimes been seen. This saline precipitation commences indifferently in any part of the mass, and commonly shows itself in several points simultaneously, these being usually seated near the centre ; it is far from unusual, however, to find most accumulation at the peri- phery, and not a few cases have been mentioned by Meckel, Louis, and others, in which the central parts, still fibrous, have been found encased in an earthy shell of variable thick- ness. The density of the calcareous matter (grey or yellowish in colour) varies greatly. If it be most common to find this substance friable and porous, in other cases, the saline substance is extremely hard and dense, resem- bling marble or eburnated bone. From Pro- fessor Daniell's analysis of a large tumour, de- scribed by Mr. Arnott (Med. Chir. Trans, xxiii. p. 202), we may infer the great extent to which the animal constituents may be re- placed by inorganic salts, as also the nature of these : here were found, animal matter, including water and ammoniacal salts, So ; phosphate of lime, with a small quantity of phosphate of magnesia, 56 ; carbonate of lime, o ; alkaline sulphates, phosphates, and muriates, 4=100. The extent of the growth converted into calcareous matter varies great- ly. Bayle refers to a tumour larger than a new-born infant's head, containing ten points of " ossification," — the larger scarcely the size of a pea, the smaller not bigger than a grain of wheat : Mr. Arnott's case exemplifies the opposite extreme of almost total conversion into saline substance. W^hen either converted altogether into earthy matter, or provided with an earthy crust of variable thickness, these bodies have been described as " calculi." Occurring most frequently in the uterus, these concretions of fibrous origin have also been ob-erved in the cranium by Cruveilhier (Rev. Med. Sept. 1833), by Krull and others. We have seen one as large as a walnut, wliich had been connected with the integuments of the face, in the possession of Mr. Liston. The period at which calcareous deposition commences is altogether accidental. The size of growths has no influence upon it : the largest tumour we ever met with con- tained not -a single earthy particle, visible with the naked eye ; while it is common to find very small growths partially calcareous, and small and large tumours in the same uterus mav present this change to an equal amount. It has even been maintained by Sebastian, that ossiform deposit is more common in small than large tumours ; but although this idea may be rendered probable d priori by the con- sideration that the occurrence of tliis change would prevent further enlargement of the pro- per fibrous structure, yet we doubt strongly its being supported by facts. With the pro- gress of saline precipitation (obviously so when the earthy changes occur on the peripheric surface, less distinctly and rapidly, though not less really, when they arise in the centra! parts) the connection of these growths with sur- rounding tissues, becomes less and less inti- mate ; the vessels undergo obliteration, and a few filamentous shreds may alone keep up the union, until eventually the calcareous mass ceases to have structural connection with the organs. This condition is in some cases the prelude to its expulsion from the body. The saline matter sometimes appears to act as an irritant on the adjoining fibrous structure, and induce local exudation, suppurative or other- wise ; probal)ly this is the state referred to by Bayle, as "caries" of the alleged osseous struc- rure of a fibroma. Fibrous tumours of the reddish variety, soft, vascular, and of loose texture, are subject to internal congestion, which when these growths are situated in certain situations, as for example, under the mucous membrane of the uterus, may, aided by expulsive efforts of that organ, lead to rupture of the superficial layers of the growth, and terminate in external haemorrhage. According to Madame Boivin, such tumours may be regarded to a certain extent as of erectile nature, inasmuch as they admit of becoming hard and tumid with blood at certain periods, especially the catamenial. Hemorrhage into the substance of the growth is a condition occasionally observed. Andral has noticed it, and we have seen a tumour containing a clot of considerable size. Numerous small cavities are occasionally observed in these masses filled w ith red, and manifestly bloody, serosity ; doubtless blood in an altered condition. These accumulations saturate and disintegrate eventually much of the solid substance. Like all vascular structures, these growths are occasionally seized with inflammation — the hard variety much less frequently than the soft. This occurrence may be announced by severe local and general symptoms, increased by the participation of the surrounding tissues. The products of inflammation exuded into the substance soften and disintegrate it ; pus of ^ K 2 132 PRODUCTS, ADVENTITIOUS. pure character is rarely observed however. The tendency to inflammation is extremely slight, inherently, in these formations ; when it occurs, it arises as a secondary consequence of their mechanical action on surrounding parts. This action produces various derangements of function of those parts, which are followed in them by irritative action, eventually spread- ing to the adventitious mass. The proof is, that growths so seated as not to lead to irri- tation of adjoining textures (sub-peritoneal pedunculated uterine tumours, for example) never, so far as our own observation and all recorded experience goes, become the seat of inflammation. We do not, however, mean to deny that in tumours of soft texture and abundantly vascular, an intrinsic process of in- flammation may not possibly arise. Sphacelus may be the result of the former kind of inflam- mation ; but this change, according to our ob- servation, very rarely occurs with its ordinary anatomical characters. Melanic colouring matter is sometimes de- posited in abundance in these growths. Dr. Carswell (Elementary Forms of Dis. Melano- ma, pL \.fig. iv.) has figured a very beautiful and characteristic specimen of this kind. The softer species of fibrous maes has in the uterus been sometimes found to contain steatomatous matter and hair. Krull has given .a rough sketch of a uterine fibrous tumour, the central j)art of which con- tained vessels, some of them capable of ad- mitting a pen, and said to present somewhat the characters of " erectile tissue" — a term very vaguely used. Diflfereiit notions have been held as to the possibility of fibrous tumours "becoming can- cerous." The difficulty in deciding this ques- tion has ai'isen from the total want of definite meaning in the minds of authors as to what constitutes "becoming cancerous." If the phrase be applied in the manner which seems the only rational and sound one, that is, to parts, whether adventitious or not^ in which the development of one or the other of three species of cancerous formation occurs, the perplexity of the question vanishes at once. The growth of cancerous substance in fibrous tumours is, in truth, at the least, materially more rare than in any natural vascularized tissue, "We have never ourselves seen a particle of true scirrhus, encephaloid or colloid, in the interior of a fibrous tumour proper. The assertion of Du- puytren and certain of his copyists, that fibrous tumours frequently become carcino- matous, is easily explained; they confound the fungative and intractable sores sometimes arising on the uterine surface and adjoining sub-mucous fibrous tumour, with cancerous disease — applying the terra, with a vagueness subversive of all correctness in morbid ana- tomy and in pathology, to every sore resist- ing treatnient and affecting the constitution by its discharge and irritative agency. As well might they call the fungating sore, produced in the tongue or cheek In- a carious tooth, a cancer. The total expulsion of fibrous tumours from the body, is a phenomenon of less uncommon occurrence, than is usually supposed. It is effected while the mass possesses its original fibrous constitution, or after its conversion into earthy matter : the process in the latter case is much simpler than in the former, as the organic connections of the mass have been gradually destroyed in the manner already I'eierred to ; it is likewise of much more fre- quent occurrence. While yet fibrous, the growth may be expelled as a single mass or piecemeal; more rarely in the former way. The conditions necessary for its accomplish- ment are, that it should be separated from its connections, and, this once effected, that it should be so seated as to drop from the body spontaneously, or be under the influence of some expelling force. In the case of the uterus, the expulsive efforts of the organ lead to the removal of the masses (especially if seated under the mucous membrane) at a much earlier period, than their meje anato- mical state would lead us to expect. The museum of University College contains a portion of fibrous tumour, expelled from the uterus in this manner ; submitted to micro- scopical examination, we found it composed of precisely the elements already described. The constitution of these growths would lead us to expect their local reproduction, if partially removed. Observation confirms this view. Cruveilhier describes, from the prac- tice of Dupuytren, a case of fibrous tumour growing from the interior of the body of the lower maxilla, in which reproduction took place twice after imperfect removal with the knife. The simple tissues in which fibrous tu- mours are observed are : the cellidar ; the fibrous J rarely, if ever, the osseous properly so called ; the nervous. The compound tissues and organs in which they are more or less frequently developed are : — the bones, in immediate connection with the endosteum, or more especially the periosteum; the sub- mucous tissue of the pharynx, more rarely of the CESophagus, of the stomach and intestines; the subperitoneal tissue; the submucous tis- sue of the larynx, the nares, the frontal and sphenoid sinuses ; the sub-pleural tissue ; the arterial tissue ; the ovaries ; the Fallopian tubes; the uterus ; the vagina ; the mamma; the testicle ; the dura mater in its subjacent cellular tissue ; the nerves ; the thyroid gland ; the thymus gland. Of these various parts, the uterus, dura mater, ovary, and manjma suffer, especially the two former, with incomparably the greatest frequency. A single one, or several fibrous tumours may exist in the same body. Usually numerous, for example, when affecting the dura mater; they are commonly single in the bones. Their coexistence in several distinct organs is extremely rare. EXCHOXDROMA. Enchondroma (from e7xoi'S,ooc, carfilagi' 710US,) is the name recently proposed by Miillcr for a species of cartilaginous growth, not unknown to previous observers, but by PRODUCTS, ADVENTITIOUS. 133 many surgical writers confoundefl, under the erroneous name of *' cartilaginous exostosis " (erroneous, if for no other reason, because the formation in question may spring from other tissues than bone), with products of essentially different character^ and by some other authors described as colloid cancer. When uncut, enchondroma exhibits itself as a tumour of moderate size and spheroidal non-lobulated shape, encased in cellular mem- brane, or (if it spring from bone) in perios- teum, ossifted or not. The section discovers a firmly gelatinous substance, rather pellucid, of very pale greyish or greenish yellow tint, set (without ftrm adhesion) in loculi inclined to spheroidal outline, varying in size, and having their walls formed of a dense dull white tissue {Jig. 9o)> One of the rough marks Fig. 95. Section of Enchondroma. (After Jliiller.) of distinction between this growth and colloid cancer consists in the mode of arrangement of the walls of the loculi : in the latter, when fully grown, the walls seem cut across sharply at right angles with their course ; in the for- mer it is extremely common to^ find the walls exhibiting flat and extensive surfaces to the eye, as though the locuh had been opened to a very small extent on'y. The general mass is firm ; when the invest- ment is periosteal or bony, proportionably increased. The intra-locular matter is in it- self soft, yet has a sharp fracture. Bony matter in its interior of course increases its consistence, and may be formed of: 1, the walls of the loc»!i converted into thin osseous plates, which give a crackling cri.spness to the mass; 2, particles of the spongy tissue of the original bone in which it has grown ; 3, sta- lactiform osteophytes springing into its sub- stance. No appnearance of vessels strikes the un- assisted eye in these masses ; but von Wal- ther and Weber (Grafe and Walther's Journ., b. xxiii. s. 351.) are said by Miiller to have injected the walls of the loculi. Microscopically examined, the fibrous por- tion of the gro\\ th is found to be composed of transparent interwoven fibres. The jelly- like part consists of cells several times larger than the red blood-corpuscle, generally speak- ing, containing only nuclei in their interior, but in some instances two or three sub-cells, each provided with its own nucleus. The nuclei, flattened, oval or circular, vary in diameter. The cells (except in excessively rare cases) are in close contact with each other, and no intcr-cell substance discern- ible between them : the cartilaginous ma- terial does not advance beyond the embryonic stage. Such is Muller's description ; Ixit it is certain that tumours having the characters of enchondroma perfectly developed to the naked eye, and \ielding gelatin, may be wholly deficient in cartilage corpuscles, and contain simple granulated cells in a fibrous stroma, Spiculated bone corpuscles are sometimes scattered through the tumour. From this account it would appear, that although the endogenous mode of growth of the cells occurs occasionally in tkis forma- tion, it is nehher uniform nor constant ; their development proceeds m.ore frequently from blastema lying outside such cells as are already evolved. Tne endogenous development was observed especially by Miiller in an enchon- droma of the parotid gland. Whether the inter-cell substance is generated by thickening of the walls of the cells, or by the hardening of a blastema unconnected, except in respect of proximity, with these, is matter of dispute. Enchondroma is essentially composed either of chondrin or of glutin ; of the former in by far the greater number of cases ; of the latter, in Miilltr's specimen connected with the parotid gland, and in another connected with the ileum, recently added to the Uni- versity College Collection. The bones are the favourite seat of this growth.. Miiller has collected thirty-six cases, m thirty-two of which those organs were af- fected ; the metacarpus and j}/iulanges 25 times; the tibia 3 ; the ileum 1 ; the cranium 1 ; the ribs 1. Of the R)ur remaining tumours, 1 ex- isted in the parotid ; 1 in the mairma of a dog ; 2 in the testicle. In its favourite seat — the metacarpus and phalanges — this dis- ease produces singular distortion and irregular tuberousness of the hand (^g. 96). Fig. 96. Enchondroma^ from model in Univ. Coll. JIus. Enchondroma, springing from bone, is in- vested or not with a bony capsule. When it grows in the interior of a long bone, expan- sion, and not perforation of the shell, occurs; the cancellated structure first, and then the K 3 134 PRODUCTS, ADVENTITIOUS. cortical, undergo softening and rarefaction, and are gradually spread out into a globular sac. New bony matter is also thrown out, help- ing to complete the capsule, which is, even with this assistance, commonly imperfect. When developed in bones of very spongy texture, perforation may, according to Miiller, occur, instead of expansion; we believe that, in at least some such cases, the growth originates in the sub-periosteal cellular membrane. In this latter variety the form is less regularly spheroidal than in the other ; but the texture is the same in both. The progress of enchondroma is slow ; its effects fundamentally are purely mechanical. Adhesion of the skin only occurs as an acci- dental effect of inflammation : rupture of that membrana only from excessive distension ; the resulting ulcer may discharge abundantly, and inflammation arise from this cause, as from external injuries, but not apparently from in- trinsic spontaneous changes. Enchondroma of the bones, hke every other affection of those organs attended with en- largement, has been described under the names osteosarcoma, osteosteatoma, and -spina ventosa — terms devoid of definite significa- tion. Scarpa speaks of it as " malignant exostosis," a double misnomer — for its course differs essentially, as has been seen, from that of cancerous maladies, and it does not necessarily spring from bone. Colloid cancer might possibly be confounded with enchondroma. We have already alluded to a rude mark of distinction between the two products ; further, colloid cancer rarely (never so far as our experience goes) occurs in bone, the chosen site of enchondroma ; the effects of the two products on adjoining tissues are essentially different — enchon- droma never infiltrates structures, colloid fre- quently does ; colloid never contains patches of bone, enchondroma does so commonly ; colloid is of protein basis, enchondroma yields chondrin, or (rarely) glutin. Certain sarcomata of the maxillEe have much outward reseniblance to enchondroma ; but thej' contain spherical cells with granules and fusiform corpihscles, and are besides of albuminous composition. § 3. OSTEOMA. The arrangement of abnormal ossifications has puzzled more than one pathologist. Excluding exostosis and hyperostosis (mere local and general hypertrophies) we propose to examine here all varieties of bone-produc- tion VI unnatural sites. We adopt this course, in order to avoid recurrence to the subject un- der the head of Pseudo Tissues, being aware that ossiform masses, having the generic attri- butes of Growths, ought alone to figure in the present place. Hypertrophy and new produc- tion of bone, as in the venereal node, are fre- quently associated ; and adventitious bone (whether springing from a new cartilaginous matrix or not) is very rarely perfect micro- scopically, perhaps never so chemicall}' : two fundamental propositions. Adventitious bone forms (a) as an infiltra- tion of natural tissues ; {b) as the callus of fractured cartilage ; (c) as an osteophyte ; (d) as an ostema ; (e) as an osteoid ; (/) as an in- filtration of new products. (o) In the natural tissues. Articular carti- lages ossify in some situations with advance of hfe, as for instance, in the cranium ; the ma- terial uniting eroded articular surfaces ossifies ; ossification of the costal and laryngeal carti- lages (perhaps more common in phthisis, in proportion to the age at death, than in other maladies) is af?ected by calcareous deposition in the cartilage cells and inter-cell substance, and by generation of new bone lacunre. Carti- lage miirbidly ossified, as that naturally ossi- fied, yields glutin and not chondrin. The anterior vertebral ligament is sometimes os- sified in tubercular caries of the spine. We have seen the tendons of the legs infiltrated with ossiform substance. The fibrous cap- sules of the spleen and kidneys are sometimes thus affected, and aponeuroses and fascicB are often, and the elastic ligamentum nuchae, more rarely, in a similar predicament. — Cellular membrane. The submucous tiissue of the gall- bladder; the subserous of the pleura (as a specimen before us proves) ; the subretinal ; the intra-muscuJar ; the parenchymatous (of the liver) ; are all the occasional seats of bone de- velopment. Muscle has disappeared and been replaced by bone in some rare cases ; the cri/s- talline lens has been similarly destroyed. {b) Fractured cartilage is healed not by cartilaginous, but by fibrous or osseous, sub- stance. (c) Under the name of osteophyte (Lobstein) we include ossiform products generated ex- ternally to, but under the influence of, some one of the natural bones. Formed from extra-osseous exudation an osteophyte may be separated from its parent bone, without necessary injury of this (herein differing from true exostosis); and is produced indepen- dently of, or in connection with, other pre- existing new formations. Osteophytes assume shapes singular and various, yet in some measure characteristic of their origin. Thus they are flat, and more or less broad in nodes ; narrow, triangular, and semicircular in cephalliEematoma ; Iblia- ceous, (yig. 97), stalactiform, cauliflower, Fig. 97, FoUaceous osteophyte of the clavkle ; the folice (h) runninq at riqlit angles with the axis of the txme (a). {U. C:3Ius.) (U. C. Mus.), or stellate, when plunging into soft growths ; styloid when passing in front PRODUCTS, ADVENTITIOUS. 135 of a vertebra destroyed by caries ; sacciform, when investing a soft growth from bone ; warty, when found about gouty joints ; inem- braniform and lace-hke in the cranium of pregnant women. The flat osteophyte (sometimes separable from the subjacent bone) is best exemphfied in nodes, though it forms under the influence of common periostitis or adjoining inflam- mation, as beautifully shown by the ribs of an old sufi^erer from empyema, preserved in the University College Museum. If a node be carefully examined, it will be found in part to consist of hypertrophy with rarefaction of the superficial stratum of the original bone ; and in part of ossified subperiosteal exudation. The canaliculi in the latter run at right angles with the axis of the bone, — proving absolutely the existence of a sef arate centre of ossification : the fact is exemplified on a large scale, in jig. 97. And it is further illus- trated by a portion of carious lower jaw-bone (now before us), separated from the face of a dipper of Congreve matches, labouring under the singular disease peculiar to workers with phosphorus. On the inner surface of the ramus of the bone (kindly lent to us by Mr. Quain, whose patient the man was *,) appears a flattish osteophyte, partly fibrillar, partly porous and pumice-stone like, of dark -greyish colour, and easily separable at the edge from the maxillary surface : elsewhere are friable earthy-looking particles. But the most singular of osteophytic pro- ductions is certainly that which forms in menibraniform patches between the cranium and dura-mater of a certain (as yet unsettled) proportion of pregnant women. The natural history of this production (of which a beauti- ful specimen lies before us) has been unravelled with great sagacity by M. Ducrest-I Exuda- tion matter soft, pulpy, and reddish, forms the matrix of the future osteophyte ; it soon becomes sandy to the feel ; subsequently hard particles of some size are felt, and these form eventually one, more or less perfectly, contin- uous plate. The frontal regions are its chosen seat, and M. Ducrest shows that its formation occurs symmetrically. Its thick- ness does not exceed a sixth of an inch, and is generally much less ; the specimen before \\% (irregular thickness from point to point gives this a lace-like appearance) forms a coating for the entire base and upper arch of the skull ; but its superfical extent is very rarely so considerable. When fresh it is of red colour ; twice (in jaundiced women) M. Ducrest found it yellow. This production, which entails no symptoms, is more prone to appear in young than in more aged women. id) Osteoma. By osteoma we understand a growth composed of bone, and either (a) altogether free from, or (b) having but very slight, connection with any part of the skele- * This man is now in excellent health, and ma- nages to masticate with the aid of a fibrous represent- ative of his lost jaw. t ^Me'moires de la Soc. Me'd. d'Observation de Paris, t. ii. ton. Tumours of the former kind (a) are of excessive rarity, and are perhaps only met with as results of bony infiltration of a pre- existing i^lastic mass, either of the serous cavities or of the parenchymata ; it seems un- necessary to insist upon the greater frequency of calcification than of true ossification of such masses. Tumours of the latter kind (b) are best exemplified by growths from bone, gene- rally termed pedunculated exostoses, in which the peduncle may be so small, and the body of the growth comparatively so large, that a centre of ossification distinct from the original bone appears to exist. Such produc- tions are not very unfrequent about the pha- langes of the toes ^ their texture is generally loose, but may be eburniform from density. (e) Osteoid. — Under the names of osteoid or ossif}ing fungous tumour, Miiller de- scribes a growth of slow or rapid course, generally springing from the surface of bones, sometimes acquiring great bulk, composed of porous or close osseous texture, and of a greyish white, vascular, nodulated substance, of the consistence of fibro-cartilage, the latter lying in the interstices of the former. The softer substance furnishes neither glutin nor chondrin by boiling, and exhibits a dense fibrous rete under the microscope, containing a few nucleated cells in its meshes. The for- mation of osteoid growths seems dependent on a peculiar diathesis ; they generally appear at first on one bone, but may eventually in- vade several bones and certain soft parts — the lungs, great vessels, &c. The removal of a primary growth by amputation does not pre- vent the development of others internally. Cruveilhier's osteochondrophyte (Anat. Path, livrais, .34), is a production of this class ; this writer calls the soft part of the tumour carti- lage, but gives no proof of its being so. (/) Bone formation in the interior of new products (exclusive of osteophytes springing from some part of the skeleton) is very rare. We have never seen such bone in cancer or in fibroma ; but there is sufficient evidence that it has, in some rare instunces, been ob- served. Of Undetermined Basis. COLLOMA. Perhaps the word CoUoma will not be objected to as a pro tempore name for the gelatinous-looking matter, which is of common occurrence in the interior of cysts, and occurs less frequently, unprotected by such invest- ment, in the hmbs and elsewhere. Tremulous and soft, sometimes sufficiently so to be almost poured from the part containing it ; generally amorphous, sometimes fibrillar, never stromal, as seen with the naked eye, this substance appears transparent and amorphous under the microscope. It contains no interstitial vessels. This substance yields no gelatin by boil- ing ; nor is it composed of albumen (though it may fiirnish traces of this principle) : it^^is therefore chemically difl^erent from the jellv- K 4 136 PRODUCTS, ADVENTITIOUS. like matter of true gelatin-yielding growths, and of colloid cancer ; from both which it also completely differs in structural characters. Miiller figures under the title of Collonema a soft gelatmiform tumour of the brain (seen also in the breast), composed of grey-coloured cells, a few fibres and vessels, and acicular cystals, soluble in boiling aether. The re- actions of the growth in the brain most •closely corresponded to those of ptyalin (?) ; that in the breast contained .a minute quantity of casein. SUB^ORDER II. INFILTRATING GROWTHS. CANCER OR CARCINOMA.* In this sub-order we place as a genus the .product Carcinoma, containing three species — encephaloid or soft, scirrhus or hard, and colloid or jelly-like. Carcinoma. " The union of these three morbid structures," as we have .elsewhere observed, " into a distinct genus, i.s, in truth, not a mere nosological artifice : it is manifest that the formations, to which I thus apply the generic term cancer, possess characters entitling them to be grouped to- gether, and separated from all others to the generation of which the organism is ex- posed. They agree anntomicalli/ , for they are all composed of elements forming a combina- tion without its counterpart, either in other adventitious products or in the natural struc- tures : they agree chemically, for they are ail distinguished by the vast predominance of protein-compounds in their fabric ; they agree physiologically, for they all .possess in them- selves the power of grov/th and of extending by infiltrating surrounding tissues, and so producing an appearance of assimilating to their proper substance the most heterogene- ous materials, — an inherent tendency to de- struction, and the faculty of local reproduc- tion; they agree pathologically, for they all tend to affect simultaneously or consecutively • various organs in the body, and produce that depraved state of the constitution known as the cancerous cachexia." But, on the other hand, these three structures are not one and the same ab viilio, as is contended by some writers: each may be developed in the others ; but encephaloid stands apart from its co-spe- cies by containing true cancer-elements in greatest abundance, and in the purest and most unadulterated form, — scirrhus derives speciality from its lavish supply of fibre, — colloid from an unimitated condition of gela- tinousness. And, again, we maintain that the * As the pre.sent article has already readied a considerable length, and as we have very fully treated the subject of .Cancer in another work, we shall confine ourselves hei-e to a statement of some few facts bearing on the morbid anatomy of cancer- ous groAvths. We are the more disposed to venture upon this course, as nothing Avhich has, to oiu* knowledge, been made public since the appearance of the work in question, requires us to add to, or take from, any of the doctrines or expositions of fact jt contains. three products are not mere varieties, — they are actual species, because each of them, as just stated, has its own constant structural attribute.* The ultimate elements met with in cancer- ous Growths are of three kinds, — essential, almost essential, and merely contingent. (a) The essential elements are granules, cells, fibres, blastema, and vessels. Granules -exist to various amounts in all varieties of cancer ; average tohoo^ mch in diameter, and either float free, or are seated within cells, or upon or between fibres. They are composed of a protein-substance, or of fat. The cells of cancer are spherical or imperfectly caudate. The spherical variety (sometimes oval or discoid) measuring, on an average, about of an inch, may reach only the -gr-jVo of an inch, or, on the other hand, attain the diameter of -^^^ of an inch, in diameter. The cells of small dimensions are particularly to be seen in scirrhus, where endogenous cell- production is rare ; the bulky class in colloid cancer, where they stantl in the relation of parent-cells to a contained progeny of sub- cells. The thickness and transparency of the cell-wall vary ; it is sometimes collapsed, sometimes full and tense ; almost always colourless. The caudate variety of cell exhi- bits itself under two forms : first, that of an irregularly branched corpuscle, having in its interior a spherical cell, itself provided in turn with a nucleus or even containing nucleated sub'cells {fg. 98) ; secondly, that of the J^;g..98. Caudate cells {from encephaloid of the stomach), con- taining nucleated sub-cells. Length Trloot^ to ih^^ of an inch ; vddth ^roo^^ to og'o^th inch. Magni- fied 400 diams. (From Author's work on Cancer.) fusiform cell seen in earconiirtous Growths (see fig. 93, p. 127), and in exudation-matter undergoing development into pseudo-fibrous tissue. The first form of caudate cell is scat- tered in an isolated manner through the growth ; the second may accumulate in fasci- culated bundles, so as to simulate fibre. (See fig. 93, p. 127.) The contents of cells are a cer- tain fluid, granules, nuclei, and sub-cells. Gra- nules are abundant in the cells, more especially, of scirrhus. The nucleus of the cancer-cell is an * The diA-ision into species is objected to as defi- cient in the perfection of zoological classifications. Who, except the artificer of the objection, could have imagined, that even an attempt was made t» reach such perfection ? oval, flattened, parietal, comparatively opaque body, generally speaking of large size in pro- portion to its cell, and often exhibiting a furrow on its surface or indentation at its edge, (see Jig. 6, a. of the author's work on Cancer), a condition preparatory to its split- ting into two. Each nucleus is supplied with one, two, or, it may be, so many as four minute bright corpuscles — its nucleoli, which in turn probably contain sub-nucleoli. When a nu- cleus splits in the manner referred to, the resultant bodies may be fairly regarded as sub- cells, — they are manifestly hollow, granular, and themselves nucleated * The diameter of the nucleus varies between the-g-^o and g-oVo of an inch, averaging gJo^ ofan inch. Fibns exist under different forms in cancer. First, delicate, non-adherent broken fibrils occur in most specimens. Secondly, true fibrous tissue occurs in the loculus-walls of colloid, and forms th-e stroma of scirrhus. Thirdly, exces- sively delicate, almost transparent fibres exist in a special variety of soft cancer, the fasciculate. The unevolved blastema of a cancerous growth varies in quantity, and is perfectly fluid, or somewhat viscid. Particles of amorphous substance, gelatinising under acetic acid, may sometimes be found associated with it. The vessels of cancer are either those of the natural structure affected, or are actual new forma- tions ; they are exceedingly abundant or very few in number. The veins are frequently plugged with cancerous matter, so as to pre- vent them from being injected. (b) We are disposed to regard fat as an almost essential element of cancer, (or rather as a substance tending to be produced where- ever cancer exists,) so constant is its appear- ance, either in the oil-globule or the granule forms (adipose-cells, if present, come from the implicated natural tissue). When fat abounds in these growths, it appears to have the effect of altering the form of the cancer-cell, and certainly modifies the naked-eye characters of the tumour. (c) The contingent materials met with in carcinoma are saline particles, crystalline (Op. cit. Jig. 11) or amorphous and calca- reous,— the latter in very rare instances accu- mulating sufficiently to become perceptible to the naked eye (calcification ;) crystals of cholesterin and patches of cholesteatoma; per- haps in very rare instances tuberculous depo- sifj" ; melanic matter ; blood fluid, clotted, in the state of fibrinous haematoma, or of " apoplectic cyst ;" exudation-matter with its spherical and fusiform cell ; pus ; and (on ulcerated surfaces) certain epizoa and epi- phyta. The pseudo-tissues which may be actually formed within the area of cancer (any natural texture may be invested by cancer) * "Where a gvj'stem of cell-encasement, such as that observed in cancer prevails, it is plain, difficulty must be felt in assigning with precision the titles of sub-cell, nucleus, and nucleolus. f We have never seen this, and we know that the naked-eye aspect of tubercle may be simulated in an encephaloid growth by excessive accumulation of fat. are epithelium, the cellular, serous, fibrous, and elastic tissues and blood vessel. Spicu- lated osteophytes, preceded (sometimes at least) by sprouting cartilage, not unfrequently plunge into the substance of cancerous growths from some connected part of the skeleton : an isolated generation of true bony structure, in a nidus of blood-blastema, within a cancerous tumour, seems a possible occur- rence (it is at the least, a singularly rare one) ; but the possibility of such generation in actual cancer-substance seems only admissible on the principle that the freaks of nature are bound- less in their variety. Built up of materials, such as these, are all cancers. Encephaloid, soft, brain-like, rapid in its evolution, attaining great bulk, highly vas- cular, prone to bleed and fungate, is microsco- pically distinguished by its deficiency in fibrous stroma and the abundance of its fluid blastema and its cells. Scirrhus, hard, tough, slow in growth, and reaching moderate dimensions only, poor in vessels, rich in fibre, differs mi- croscopically from its co- species in its abun- dance of fibrous stroma and the comparative fewness of its cells, which mainly grow on the exogenous plan. Colloid, crisp in its mass, soft in the jelly-like ingredient that fills its loculi (models of the spherical loculus), but slightly vascular and semi-transparent, stands apart microscopically from encepha- loid in the well-marked fibrousness of its loculus-walls, from scirrhus in the abundance of its endogenously-growing cells, from both in the abundance of its viscid jelly-like element. The chemistry of cancer is yet in its in- fancy. Its organic basis is essentially protein, — its saline constituents those of the blood. That there is a difference in chemical nature between colloid and the other species, seems plain from the fact that the former retains, the latter lose, their transparency in alcohol : Miil- ler conjectures that colloid contains a com- pound analogous to ptyalin. Microchemically the cells of cancer are insoluble in cold and boiling water, and are not seriously affected (in respect of solution) by acetic acid : the cell-wall has been said to disappear under the influence of the diluted acid ; but it is simply rendered pale, and may be restored by the ioduretted solution of iodide of potassium, which at the same time greatly deepens the colour of the nucleus. We have already said (p. 124) that a con- stant and unfailing microscopical characteristic of cancer has hitherto been vainly sought for ; the following propositions will serve as a com- mentary on, and, in some sort, a justification of, the statement. (1.) Parent cells, con- taining within them sub-cells having darker nuclei, and these, in turn, bright nucleoli, are strongly characteristic of cancer : but such cells are rare in, and may be altogether absent from, scirrhus; encephaloid in some phases of its growth may also be without them. (2.) The shapelessly-caudate cell (see Jig, 98) seems significant of cancer ; but it may be absent from encephaloid, and it is ex« cessively rare in scirrhus or colloid. (3.) A 138 PRODUCTS, ADVENTITIOUS. tumour may present to the naked eye the cha- racters of encephaloid, be the seat of interstitial haemorrhage, affect the communicating lymph- atic glands, run in ail respects the course of cancer, and nevertheless contain no cells but such as are undistinguishable, in the present state of knowledge, from common exudation- cells. (4.) Nay more, while a primary " malignant" tumour contains these cells alone, the lymphatic glands secondarily af- fected may contain compound nucleated cells, spherical and shapelessly-caudate.* (5.) The granular and imperfectly nucleated cell of scirrhus is valueless as an evidence of cancer. (6.) The true fusiform cell {fig. 93) is an adventitious formation when it occurs in cancer, and has no diagnostic signification. (7.) The association of fibre and cell-structure, which will distinguish scirrhus from fibrous tumour, may be totally wanting in encepha- loid, and exists in sarcoma and enchondroma. (8.) If fat be associated in large quantity with fibre and cell-structure, the certainty that cancer is present becomes great, but not ab- solute. The property of infiltration, which serves well, as we have shown (p. 125), to distinguish cancer from other groiuihs nosologically, fails practically in the distinction of tumours gene- rally, because a true cancer is not necessarily infiltrated, and because tubercle and exuda- tion-matter may be infiltrated. In ultimate analysis the single character least likely to deceive is this : if a tumour be cancerous, it will yield on pressure an opaque, whitish (milky or creamy-looking) albuminous fluid f; if it be not cancerous, it will not yield a fluid of these qualities. Order III. — Pseldo-Tissues. The blastema from which Pseudo-Tissues are evolved is commonly known as coagulable lymph, itself nothing more than liquor san- guinis slightly modified in nature, and in the proportion of its elements (the modification consisting in excess of fibrin, — it comes from hyperinotic blood, — and in the presence of gelatin, Mulder), and like it composed of water, fibrin, albumen, fat and salts. Pro- duced by exudation from the vessels, homo- geneous and amorphous, this fluid soon be- comes the seat of cell-formation, the cell being that already described as the com- pound granule corpuscle. The fibrin it con- tains coagulates into patches or flakes of yellowish grey colour, semi-transparent, amor- phous to the naked eye, but fibrillar (in parallel fasciculated rows) under the micro- scope, the cells (and abundant granules) ap- pearing set in or upon the fibrils. Ha-matin, * Islw Ellis has recently ascertained this fact in examining a testicle, and communicating lymphatic glands. f We have found this the fact even vnih cancers of excessive transparenc}' and wateriness of look. (See Op. cit. p. 17.) Colloid cancer is compara- tively poor in this kind of fluid ; but fortimately its other characters unfailingly identify it. or entire blood-disks may appear, and pus corpuscles be produced, amid these coagula. Now the issue of this exudation-matter (which seems regulated rather by the consti- tutional state than by its own nature) may be of two kinds. Either a permanent material sui generis (which, for want of a better name, we will call Indurntion-matter) is produced ; or a structure resembling some one or other of the natural adult tissues is evolved. The former result signifies a lower plastic power than the latter : the necessity of active con- gestion for the production of either is more than doubtful. liSDLRATION-MATTER. Coagulable lymph, destined to remain in the condition of induration-matter, becomes more and more opaque and solid, and acquires an imperfect fibrous character (as Mr. Gul- liver first showed) from simple condensation of the original fibrillated fibrin, and indepen- dently of cell-formation. The fibres become thicker, and run more flexuously, as the consistence increases, — a change probably caused by contraction from removal of water. The properties of induration-matter vary greatly. Of greyish, yellowish, or white co- lour ; opaque ; fragile and cheesy in consistence, or firm as fibro-cartilage ; of trifling, or of extreme tenacity ; rarely crisp, and generally distinctly tough ; commonly elastic ; in its firm- est condition creaking on incision ; occurring in the forms of membranous la3erf, more or less perfect sacs, nodules, patches (plane, puc- kered, cupulated, or convex), points, granules, wart-like bodies, or altogether amorphous ; essentially of protein-basis, yet yielding gela- tin in a certain proportion, prone to contain fat (granular or cholesteric), and often becom- ing the seat of saline (ossiform) deposits; induration-matter is perfectly similar to none of the natural textures. As it hardens, its texture densely and closely set, often acquires a chondroid appearance without containing a particle of true cartilage ; it is imperfectly (or not at all) vascular. Microscopically it is found to be unprovided with prolific cells ; nor are the few cells it may contain, nucleated as a general fact. It is rendered pale by acetic acid. Induration-matter is endowed to a remark- able degree with the property of slow con- traction,— a property which renders its presence most beneficial or most baneful. It is this property, on the one hand, which in the process of cicatrisation b\' granulation, reduces within reasonable limits the surface of the largest wounds ; while on the other, it may cause painful deformity, as in the instance of burns, or actually cause death, as in the instance of healing intestinal ulcers.* Presenting itself wherever vessels exist, and entering non-vascular textures by imbibition; * Tlie cure of ulcers of the small intestine in continued fever and in phthisis, and of the large bowel in chronic inflammation, has more than once proved the cause of fatal stricture. PRODUCTS, ADVENTITIOUS. 139 co-existing with all varieties of textiiral change, and exercising important influences on local nutrition, induration-matter would require a volume for its full description. We must content ourselves with an enumeration of some of the principal sites in which it occurs. Induration-matter forms: (A.) On membranous surfaces, where it is known under the names of pseudo-membrane, matter of adhesions, &c. Of the serous class the pleura is by far its most common seat ; next follows the pericardium ; then the peritonaeum ; then appear the tunica vaginalis and synovial mem- branes; and longo intervallo the arachnoid.* Among mucous membranes it appears on the respiration- surface in croup, plastic bronch- itis, and pneumonia (in all which situations it is not distantly allied to diphtheritic de- posit), and on the intestinal surface as in dj'sentery. It appears on the endocardial and valvular surfaces in the warty and gra- nular forms ; in the arteries and veins in the patch-hke shape. The so-called glands of Pacchioni illustrate its occurrence on fibrous surfaces. (B.) Free in cavities. So it has been occasionally found forming rounded masses in the peritonijeal and pleural sacs ; the so-called " loose cartilages" in joints are in the great majority of instances composed of induration-matter; so too are those small melon-seed-like bodies, producing double saccular distension at the wrist-joint.f (C.) In the cellular membrane. The sub-cutaneous, (less frequently than the sub-mucous, and still less than the sub-serous) cellular membrane, becomes infiltrated with this material ; in parenchymatous cellular tissue it is singularly common. In addition to the ordinary cases of its occurrence in the latter, as a result of simple inflammation, it constitutes in great j:)art the substance of the morbid element infiltrating the kidney in certain cases of renal disease attended with persistent albuminuria, urine of low specific gravity, anasarca, &c.; infiltrating the capsule of Glisson, it plays a notable (but not the whole) part in hepatic cirrhosis ; and infiltrating the substance of the lung (especially in certain cases of empyema), it converts that organ more or less completely into a chondroid mass. Seated in the intra- serous fibro-cellular tissue of the cardiac valves and chordas tendineae (where it is associated sometimes with atheroma) its contractile force produces the puckerings and shortenings so fre(juently observed. (D.) As imperfect cica- trix. Wherever a solution of continuity oc=^ curs, the cicatrix may be formed of this sub- stance ; take the instance of false joints: in some situations cicatrix seems always to be thus constituted, of which more in the next section. (E.) On new surfaces. Induration" matter may form on wounded, burned, * We have never seen arachnoid adhesions, un- less in connection with tumour of the brain or meninges. Is idiopathic arachnitis always fatal ? t We have found these bodies hollow centrally ; their capsule is composed of amorphous albuminous matter with a little fat, and occasionally calcareous particles. and ulcerated surfaces; and supply a sac more or less perfect round the cavity caused by abscess, tuberculous softening, and fistulae. SUB-ORDER II. SIMULATING THE NATURAL TISSUES. When endowed with higher plastic quality exudation does not remain as induration-mat- ter, but becomes the matrix from which a structure more or less closely imitative of some natural tissue is evolved. This imita- tion is never perfect, at once physically, chemically, and physiologically, — at least in respect of the higher orders of texture. A pseudo-tissue thus generated may be wholly adventitious ; or partially so, as when design- ed for the reparation of lost parts. EXTRA-VASCULAR TISSUES. Epithelium. — On cicatrising and on fistulous surfaces, on the inner wall, or amid the con- tents, of cysts, as a coating for haematomata, and as a lining for new vessels, tessellated epithelium occurs as a purely adventitious j)roduct. The retained and accumulating epidermis forming corns and callosities, or that thrown off in excess from the skin in pi- tiriasis, or from the genito-urinary mucous surface in various states of disease, or from the intestinal surface in cholera, &c., can only be viewed as products of supersecretion. Hy- pertrophy of the papillae of the skin, with excess of epidermal formation (Univ. Coll. Mus.), a state prone to give rise to obstinate ulceration, cannot fairly be considered under the present head. Perhaps the epithelium accumulated in cutaneous sacs produced by dilatation and occlusion of sebaceous follicles may be considered adventitious. So likewise are those productions, elongated or flat, known as " horns," and which are essentially com- posed of epidermis. Commonly springing from a dilated and diseased sebaceous follicle, and mixed abundantly with fat, slightly with saline matter, the basis of the future "horn" is at first soft, subsequently becomes inspissated and hard, when its increasing dimensions, carrying it beyond the limits of the follicle, place it under the influence of the atmosphere. Layer upon layer of epidermis continues to accumulate at the surface of the follicle, and eventually a conical mass, some inches in length, may be the result. Horny-looking productions sometimes form on ulcerated surfaces, simple or cancerous. Pseudo-tumours, composed essentially of epithelium, and susceptible of vascularization, form, it is affirmed, on some mucous surfaces, — the uterine for instance. We have not met with productions of this kind. mil. — (See Tooth, p. 143.) Cartilage. — Adventitious cartilage, at one time believed to take rank among the most common, is now known to be one of the rarest of new formations : the microscope has certainly dispelled a cloud of error on this subject, by simply showing that cartilagi- nous-looking products are not necessarily 140 PRODUCTS, ADVENTITIOUS. cartilaginous. Such products are most com- monly composed of dense fibrous substance, or induration-matter, — as in the instance of so called loose cartilages of joints.* Adventitious cartilage is either of the em- bryonic or adult type : the former has already been described' under the name of enchon- droma. Cartilage of adult type, certainly, sometimes forms the matrix in which adventi- tious bone orijiinates ; this we have seen beautifully exemplified in spicular osteophytes. Analogy would lead to the admission that a cartilaginous stage should always precede bone-production ; yet not only is proof of the constancy of this stage wanting, but we have looked in vain for its traces in many specimens of adventitious bone. In a very few prepar- ations of that rare variety of false-joint in which a pseudo- synovial membrane is pro- duced, the bony surfaces (whether from frac- ture or dislocation) have exhibited a cartila- ginous look in patch-work ; but we have not had an opportunity of submitting such a speci- men to microscopical examination. Of the appearance of cartilage in various Growths enough has already been said. Nor is the production of cartilage for reparative purposes more easy. A fractured cartilage unites by dense fibrous tissue, or by bony substance. SIMPLE VASCULAR TISSUES. Cellular Tissue. — Cellular pseudo-tissue is one of the most common of adventitious for- mations, composed of associated white fibrous and yellow fibrous (elastic) fibrils. But rarely does it possess the character of the natural texture in perfection ; the distinction of its component filaments is less clear, the fasciculation of these less regular than in the typical structure. A more or less successful attempt at its production is made in all cases, where induration-matter forms, — the highest degree of perfection seems to be attained in old adhesions of serous membranes. A lapse of many months is necessary, however, to mould the new structure into its most perfect attainable form ; while on the other hand, a period ofseven days (as we have seen in a fatal case of j)leurisy) will suffice for the production of an imperfect tissue of this class. Schwannt found that embryonic cellular tissue yields no glutin ; the same fact has been ascertained by Simon:{: in respect of the adventitious cellular tissue of condylomata, — by Gueterbock, in respect of that of granula- tions. The latter observer found pyin in the water in which the granulation-substance had been boiled. At an early period of for- mation fibrin is found in association with the principle (tritoxide of protein ?) to which the name of pyin has been given ; eventually glu- * We should be unwilling to affirm that these bodies are never truly cartilaginous ; but we have examined a considerable number without disco- vering the chemical or textural qualities of that tissue. f Untersuchimgen, S. 136. % Midler's Archiv, 1839. P. 26. tin is yielded on ebullition, but it may be doubted whether the chemical constitution of the new, is ever precisely the same as that of the imitated texture. Serous Tissue. — A single layer of polygonal pavement epithelium, beneath this a basement membrane of singular tenuity, and yet beneath this a stratum of cellular tissue, constitute a serous membrane. This structure is essen- tially disposed to form shut sacs, and produce and retain a certain secretion. So far we have a texture which is often generated adventiti- ously ; but if, as is now admitted, natural serous tissue is supplied in its proper sub- stance with nerves*, it becomes a complex structure, of which a perfect adventitious copy is never generated. A new serous sac may be produced {a) by modification of natural structure, with addi- tion of a new element ; or {b) be completely adventitious. {a) In this class appear those well known cases in which pressure, with or without fric- tion, causes condensation of cellular tissue with production of epitheUum, the latter form- ing a lining for a sac of the former. So are produced new supernumerary bursJE about the knees, the shoulders of porters, between the skin and bone of stumps, between the skin and spinous processes in spinal curvature, whether primary or from caries, &c. (6) Purely adventitious serous tissue is either (a) laminar or (b) saccular. (a) By the laminar variety, we understand those strata of pseudo-serous tissue which invest false membranes in serous cavities. (b) The saccular variety comprehends cysts, primary and secondary. Primary cysts are spontaneously evolved, are capable of indefi- nite increase in number and size, through some intrinsic force, constitute in themselves the disease where they exist, form the material they contain, are closed on all sides, lined with epithelium, and simple or compound. Simple cysts occur singly or in clusters, and may appear in almost every region of the body ; their walls are of variable thickness and simply cellular, fibrous or calcareous ; their contents serous or glairy. The mamma and ovary are the most frequent seats of the clustered simple cyst. The compound cyst (cystoma) is charac- terised by its faculty of producing secondary cysts in its walls, — these a tertiary series and so on. Their closest investigator. Dr. Hodg- kin, assigns them three chief varieties of form, — the pedunculated, the intermediate, and the broad-based, for a full description of which we must refer the reader to his treatise.! The growth of the contained cysts is some- times so active, as not only to give a nodulous outline to the main mass (which may attain enormous bulk), but to cause rupture of the walls of the primary cyst. Various morbid changes, inflammatory and other, may arise * Todd and Bowman, Physiol. Anat. p. 130. t Morbid Anat. of the " Ser. and Muc. Mem* branes, vol. i. PRODUCTS, ADVENTITIOUS. 141 in these productions ; carcinoma may even, in predisposed persons, be formed in their walls, but not (so far as evidence goes) be produced in their cavity as an evolution of bhistema exuded from their Hning membrane. Miiller has recently applied the name cysto- sarcoma to growths, principally composed of a fibro-vascular texture, but invariably found to contain solitary cysts in their substance. The cysts may be solitary or compound ; the solid substance, of greater or less density, has an indistinctly fibrous structure, contains no cells, and is of albuminous basis. This growth is essentially distinct from carcinoma, but that it differs generically from sarcoma seems ques- tionable. Secondary cysts are not spontaneously generated, but form through the influence of bodies foreign to the site they occupy : around effused blood, after a series of modifications (the apoplectic cyst), around adventitious pro- ducts, extra-uterine foetuses, and bodies intro- duced from without, as musket-balls, shot, pins, &c. A sort of pseudo-cyst is sometimes produced by distension and closure of small natural cavi- ties, or of the excretory ducts of glands. In the first class we find dilated cutaneous follicles, intestinal crypts, and solitary glands ; to the second class belong cysts of the lactiferous and pancreatic tubes, of the labial and sub- maxillary glands, some of those in the testicle, and, it is commonly believed, in the kidney.* Fibrous and Elastic Pseudo-Tissues. — Of the production of white fibrous-tissue of an im- perfect kind, numerous examples have been referred to in the past pages, — it is one of the commonest of new formations. Less common by far is the generation of the yellow fibrous element, which is distinguished by resisting the action of acetic acid ; the mesh-like arrangement of bifurcated fibres is much rarer in the imitation new tissue than in its prototype, — nor does the former occur (so far as we know) in masses of any size. The modification of this texture which con- stitutes the main element of artery is doubtless produced in new vessels. Osseous Pseudo-Tissue. — The most perfect imitation of a complex natural texture is ex- emplified by adventitious bone, — produced for the reparation of injuries (Permanent Callus). It is even said that the permanent callus has all the characters of true bone, — a proposi- tion which appears to us to require more absolute proof than it has yet received. The new bony shaft, produced to supply the ravages of necrosis of the long bones, is a ruder imitation of original bone ; it is darker in colour, rough, and tuberculated on the surface, * Cystic productions in tlie kidney still require investigation — from tlie minute apparently soli- tary cyst, to those clustered masses causing de- struction, more or less complete, of the proper renal substance. Dr. Johnson (Med. Chir. Trans, vol. XXX.) adduces arguments of a novel kind to prove that the simple cyst is in reality a dilated tube ; Mr. Simon (eod. tom.) seeks to show that it is a new development within the parenchyma. and often much denser than the latter. (See 0STE03IA, p. 134.) Nervous Pseudo-Tissue. — In certain of the simpler varieties of neuroma the induration- matter mainly forming the tumour appears to contain a larger proportion of tubular fil)res, than would in the natural state fall to the share of a portion of nerve of similar length. The tissue in excess (admitting the fact to be substantiated) might, however, be rather re- garded as an hypertrophy than a new produc- tion. The regeneration of voluntary nerve (ren- dered probable by the experiments of Haigh- ton) has been proved by those of Steinriick*, Nasse, Giintherf, and Schron.J The tubules produced in the exudation, connecting the cut ends of a nerve, differ from the natural ones in being more widely apart, of smaller diameter, less parallel to each other, more intertwined, and more mixed with cellular fibrils. The time required for their produc- tion varies, — a month appears to be the shortest period yet observed ; the length of nerve which may be excised is yet unsettled. In the majority of cases, even where reproduction is seemingly perfect, the physiological action of the injured cord remains imperfect ; probably because the corresponding parts of the same fibres are not, or because sensitive and motor fibres are, brought into connection ; besides the new tubules are not the 2yrecise physical counterparts of the old, nor is their number as great as in the original texture. Cerebral substance removed from animals is replaced by a brain-like matter : the precise nature of this matter (as of that appearing in hernia cerebri in man) has not been examined sufficiently. It seems very doubtful that dynamic vesicular texture ever forms adventi- tiously. Blood-vessel. — The development of new blood-vessels, though so common, is but ill understood. They must obviously be pro- duced from pre-existing trunks, or be evolved independently. Viewed as productions from the old vessels, they have been supposed to be mere prolonga- tions of these, — a notion set aside by the fact that vessels do not terminate by open mouths. Or, again, they have been considered the pro- duce of a looping process — the increased impulse of the circulation towards the site of vascularisation being supposed, when com- bined with a relaxed state of their own tex- ture, capable of elongating the old trunks into loops : it seems probable that increased vas- cularity may, to a limited degree, be produced on this plan. Or, again, it has been conjec- tured that processes, first solid, subsequently hollow, spring from the sides of the original vessels, — an hypothesis unsupported by direct evidence and deficient in plausibility. Or, lastly, it has been maintained that the first step in the process consists of rupture of original * De Xerv. Regenerat. Berol. 1838. t Milller's Archiv. Heft V. S. 405. 1839. X Mailer's Archiv. 1840. U2 PRODUCTS, ADVENTITIOUS. vessels ; the second in the extravasation of blood ; the third in the passage of this into canals (manufactured, as it were, for its recep- tion); the fourth in the formation of walls round this blood : the difficulty in this hypothesis lies in the alleged canal-formation. The notion that new vessels are independent productions is supported: — by the analogy of the process in the vascular area of the chick ; by the fact that the new cannot at first be injected from the old vessels ; by the analo- gical fact that new blood-particles appearing in lymph in the frog are of spherical shape (as in the foetal condition), and are therefore not particles previously contained (for these are oval) in the old vessels ; by direct observation both with the naked eye and with the micro- scope. In truth in one spot of a new material to be vascularized may be seen minute uncon- nected points of blood ; at another, a number of such points united in linear juxtaposition, so as to form a streak of blood unenclosed in any distinct vessel ; elsewhere a vascular in- vestment is found for a similar streak ; further on a like piece of delicate tube divides at each extremity into a number of tapering ramifica- tions, assuming a stellate arrangement, the whole assimilable to the system of the portal vein, and capable of effecting an independent osciUation of the contained blood. What is thus seen with the naked eye is corroborated with the microscope ; but this instrument has not yet made clear either the precise structural characters or developmental process of the new vessels : we simply know that these are wider, and of thinner walls than natural capil- laries. The manner in which communication is effected between old and new vessels (when the latter first become the seat of true circii- Intion) is unknown. That the formation of new blood precedes that of new vessels seems fully established ; just as the cell-structure, destined to fill a loculus in a new growth, forms before the loculus-walls that contain it. The production of new blood and vessels signifies the appearance of various new chemi- cal compounds in the vascularized material ; the globulin formation may be understood, that of the haematin is at present inexplicable, — unless we accept the extravasation-theory above referred to, which supplies iron as required. Further observations are wanting as to the shortest possible time in which new vessels may be formed ; we have seen them in peri- tonaeal exudation aged seven days ; Everard Home speaks of their appearance in twenty- nine hours. They form in growths, indura- tion-matter, hypertrophy of natural textures, and pseudo-tissues. Generally produced on a limited, they in rare instances form on an extensive scale ; the most singular illustration of the latter appears in the new system of ves- sels generated in tuberculized lungs (Schroeder, Guillot), which effects not only a complete change in the anatomical condition, but in the physiological actions, of those organs.* * Loviis on Phthisis, ed. cit. p. 29. Erectile Tissue. — (See Angeiectom\, p. 128.) Lymph J esse/. — Schroeder van der Kolk has described l\mph vessels of new formation in peritoneal pseudo-membrane ; it is gene- rally admitted that his observations require corroboration, and we know of no other evidence bearing on the question. Fibrous and Spongy Cartilage. — Fibro-carti- lage forms in some rare instances the material by which imperfect union of bone is effected : its own losses are supplied by a similar ma- terial ; it does not appear to form in an absolutely adventitious manner. Nor does spongy cartilage grow as a new product, — and of the reparation of this texture httle is known. Hair. — The adventitious production of hairs is not singularly rare, and though, no doubt, much fantastic matter has been written on their places of attachment, the following localisations may be admitted as real. The tongue*, the caruncula lachrymahs, the cor- neaf, the internal surface of the gall-bladder j, the nymphae, the vagina, (in connection with fat) tumours of the uterus and of the fauces. § Cases of defecation of hair and of pilimiction are for obvious reasons to be received v\ith distrust II ; but the rupture of an ovarian cyst into the bhidder may sometimes have caused discharge of hair with the urine. Cysts of new formation are the favourite site of adventitious hair ; pilous cysts have been seen occupying the ovary, uterus, subcutaneous membrane, muscular substance, wails of the stomach, testicle, liver, thyroid gland, omen- tum, and peritonjEal cavity. The ovarian is of all cysts the most frequent abode of these productions. The hair is scattered through the fatty matter generally present, or adherent to the walls of the cyst, either by a bulb or by simple embedding, or by means of cretaceous particles. The colour of the hairs varies greatly, sometimes even in the same cvst ; their length from a few lines to upwards of two feet. They commonly resemble in struc- ture the hairs of the head, rarely those of the pubis : their possession of roots has been denied ; whereas ?>Ieckel considers it probable that they always have a root in the outset, losing it subsequently after separation from their seat of attachment. Tooth. — Teeth are frequently found in pilo-fiUty cysts ; there scarcely appears, indeed, to be a single authentic case of the discovery of adventitious teeth (except where produced * This has been denied hypothetically ; yet no- thing is less improbable than the occasionjil groArth of ob-vious hairs from tliis organ, seeing that some of the epithelial processes of the conical papilla; actually enclose minute hairs in the natural state. (See Todd and Bowman, Anatomy, vol. i. p. -yO.) t Gazelles, Journal de Med. t, "xxiv. p. 332. X Of more than an inch in length, by Bichat. Anat. Ge'n. t. iv. § Ford, Medical Communications, vol. i. p. 444. 1784. II Yet what is to be said of the case related bv Henrs- (Med. Chir. Trans, vol. x. p. 142. 1819) of a middle-aged man, who voided hairs of from of an inch to an inch in length -^^th the urine, some of them occasiouallv coated with uric acid ? PRODUCTS, ADVENTITIOUS. 14^ in, or close to the mouth) without coexistent hairs. Nails and true cutaneous texture are frequently present also. As transition-stages to the purely adventitious formation of teeth appear : the growth of supernumerary teeth in the jaws ; of such teeth not in the jaws, but still in the cavity of the mouth ; of such teeth in the neighbourhood of the mouth, as in the orbit.* Appearing in the mediasti- num-)-, close to the diaphragm J, in the sto- mach in the testicle, &c., they are purely adventitious. The ovarian cyst is their chosen seat, however, and their number may be very considerable. In an ovarian cyst now before us (Univ. Coll. Mus.), there are three sepa- rate sets of teeth ; in the one are 2 molars, 2 bicuspidati, and 2 canines ; in the second, 2 molars, and 1 incisor ; in the third, 6 molars, 2 bicuspidati, 2 canine, and 1 incisor, — 20 in all. A case has been recorded by Ploucquet and Autenrieth of a young sterile woman, in whom an ovarian cyst contained 300 teeth, — a fact showing that the relationship (con- tended for by Meckel and others) between the combined number and character of__adven- titious and natural teeth is imaginary. The full consideration of the mode of de- velopment and production of adventitious teeth and hair would carry us into the regions of Teratology ; and it must be confessed that the most diligent investigators have failed to find explanations for all cases. If it be true that in some instances these products are the residual parts of a regularly-formed foetus, in others evidences of an attempt to produce a fcetus (in either of which cases they may be the proceeds either of extra-uterine pregnancy or of the formation of a monster by inclusion), it is also certain, that in other instances all explanations hitherto tendered have failed of their mark. Cutaneous. — Except in such cysts as those just referred to, skin is never formed adven- titiously. Losses of this texture are repaired by a substance partaking of the characters of induration-matter and of fibrous tissue. Mucous. — Portions of mucous membrane destroyed by ulceration are replaced by indu- ration-matter, covered on the free surface with a coating of epithelium, smooth and glistening ; the border is, or is not, puckered and finely nodulated. The attempts made by Sebastian, Dr. Parkes ||, and others, to show that the reparative power goes the length of forming new intestinal mucous texture, the precise anatomical counterpart of the old, appear to us to have failed ; nor is there any evidence that the cicatrix (either of the flat or puckered variety) can even rudely discharge the ofiice of the texture it replaces. The pyogenic membrane of chronic ab- scesses, tuberculous cavities and fistulae, has many of the more obvious characteristics of * Barnes, Med. Chir. Trans, vol. iv. p. 316. t Gordon, Med. Chir. Trans, vol. xiii. p. 12. 1825. X Berlin, Sammlung, t. iii. p. 2G4. § Ruysch, Hist. Anat. Med. dec. iii. No. i. p. 2. II On the Dysentery and Hepatitis of India. mucous membrane. Of velvety look and feel ; varying (like its prototype) in colour from red to grey, slaty, or even black ; thick as the inner coat of the stomach, or thin as the lining of the frontal sinuses ; more or less closely adherent to a stratum of induration- matter (representing the submucous cellular membrane of health), and covered with epi- thelium ; capable of producing fungous vege- tation from its surface ; and utterly ina[)t to contract adhesions with itself ; — this struc- ture has evidently many claims to the title of pseudo-mucous. Its deficiency in villi and follicles simply proves that it imitates the least highly elaborated of nature's types. The microscopical characters of this formation, however, require full examination. Glandular. — Destroyed glandular texture is not reproduced ; much less does a de novo development of such texture He within the range of morbid action.; Muscle. — There is no evidence that striped muscular fibre is produced for purposes of reparation, much less as a wholly adventitious formation, Unstriped fibres occurring in the ureter, walls of the gall bladder, and other excretory organs, are rather hypertrophous, than adven- titious, products, inasmuch as they naturally exist in minute quantity in those organs. Of the truly adventitious production of this fibre nothing is satisfactorily known. SUB-CLASS II. GERM-FORMATIONS OR PARASITES. Products, whose continued existence does not depend upon direct access of nutrient fluid from the organism they inhabit ; which spring from a germ*, and simply live in, without forming part of, the individual they infest, are true Parasites. They do not in themselves constitute disease, but always indicate its presence, and sometimes entail its develop- ment ; in the latter case they may be made to propagate similar disease from organism to organism. In some rare instances the organic kingdom to which they belong is doubtful ; the great majority easily take their places among animals or vegetables. ORDER I. ANIMAL PARASITES. See Entozoa (vol. ii ). ORDER II. VEGETABLE PARASITES. Vegetable parasites form on tlie skin, on mucous membrane, on new surfiices, upon or withiri the body, and in certain of tlie fluids. They indicate the existence (on the surface, or in the fluid, affording them a habitation) of the presence of chemical decomposition, and also of the presence of some new material (albumi- nous, saccharine, &c.), the result of diseased action. Their precise influence and patho- logical power in the human subject are yet * "We set aside the notion of equivocal generation, inasmuch as observation, so far as it goes, deposes to the necessity (at least the existing necessity) of pro- pagation from germs. 144 PRODUCTS, ADVENTITIOUS. open to inquiry, but it is certain that the difficulty of killing them obstructs the cure of diseased states (porrigo favosa, for instance), in connection with which they form. They are referrible to fungi and alg£e, and commonly composed of cells arranged in a moniliform manner, and multiplying by gemmules. When forming on the external surface, they may be called epiphyta ; when within the frame, en- top hyta. The torula has been observed in the urine and in the gastric fluids (Busk) of persons labouring under saccharine diabetes ; also in the faeces, and in vomited fluids under various conditions. Three to five rounded or oval cells, upon which acetic acid produces no appreciable effect, provided sometimes with genmiules (single or more than one), — gem- mules differing from themselves simply by being smaller, — the torula of the human sub- ject is in all respects exactly like the torula cerevisiae, and sigrnfies the presence of fer- mentating matters. Mycodermatous vegetations occur as ele- ments of the crust of porrigo favosa ; they germinate underneath (and never upon) the epidermis in amorphous exudation of protein- basis thrown out by the cutis. Underneath the epidermis, covering the capsule, lies the amorphous exudation-matter in a thin layer ; beneath this, jointed cylindrical tubes, matted together with similar matter ; deeper still, fragments of tubes ; and yet further, free sporules in abundance : the elongated cells, forming the tubes, occasionally contain mole- cules,— these are visible when magnified 800 diameters.* Acetic acid, b}' lessening the opacity of the amorphous matter, renders the cells and tubes more distinct. Attempts to propagate favus by inoculation of the sporules, the matter of the crust, and the fluid of the pustules, have failed (Gruby, Bennett) ; whe- ther plants, healthy persons, or persons af- fected with porrigo, have been made the sub- jects of experiment : failures appearing to show that the parasite is incapable of germinating unless in a special soil (the amorphous exu- dation-matter), and that the production of this soil constitutes the essence of the dis- ease. Even when the special constitutional state exists, artificial introduction of the spo- rules will not call forth exudation-matter of the quality fit for their nourishment ; for in- oculation of an affected scalp fails as com- pletely as that of the skin of a healthy person. So, too, the cell of cancer must have its soil of kindred blastema, or the inoculation of its germs will fail. (See p. 124.) In plica polonica Gunsburgf found spo- rules in the substance of the hair-roots ; Dr. Miinter failed in discovering them, — they are therefore not essential. Gruby detected epi- phytes in sycosis between the root of the hair and its sheath. Speaking of entophytic development on * H. Bennett in Trans. Eoy. Soc. of Edin. vol, xv. part ii. 1842 ; see also Gruby, Comptes Rendus, 1841, 1842, and 1844. t MUller's Archiv. 1845. p. 34. diphtheritic exudation of the mucous mem- branes and skin in a former page (p. 118), the misplacement of a word gives us the appear- ance of saying that vegetable growth is less common in thrush than in the similar exuda- tion in phthisis, whereas we meant to affirm the contrary. Dr. Bennett contributes an example of entopytic growth found amid the sputa, and in the contents of cavities, in a case of phthi- sis : we have ourselves seen jointed vegetable filaments on the walls of cavities. In the fluid of pyrosis Mr. Goodsir* found a living structure closely allied to certain ge- nera of Bacillarias but most closely to the genus Gonium, among the Volvocinae; look- ing like a wool-pack (hence the name Sarcina ventriculi), bound with cord, crossing it four times at right angles, and at equal distances ; varying in dian)eter frc to of inch, and consisting (Jig. 99) of sixteen four- FiQ. 99. Tlie Sarcina ventriculi. celled frustules embedded in a square tablet of a transparent texture. GROUP II. LIQUID ADVENTITIOUS PRODUCTS. Fluids formed in localities, naturally free from them, are obviously adventitious. Patho- logically considered, fluid products are of sig- nal importance; but the consideration of their morbid anatomy wil! not long detain us. These fluids accumulate in serous cavities (dropsical) ; in the cellular membrane (oedema or anasarca) ; or in the parenchyma of organs (oedema). They may likewise form in adven- titious seats, as in cysts, and in the bullae of erysipelas, rupia and pemphigus, sudamina, &c. When pure, the fluid of dropsy of serous membranes is aqueous, transparent, free from viscidity, and colourless, or faintly yellowish. But it may be thicker, ropy, and of deeper colour, — and is commonly so in ascitic or ovarian fluid, which has been for any length of time accumulating. Es[)ecially in cases of this class, organic corpuscles may be found ; other- wise the fluid is transparent and amorphous under the microscope. In the fluid of syphi- litic rupia we have found well-constituted exudation-cells. Generally speaking the fluid of dropsy is alkaline, — we have never known it otherwise ; but it certainly is occasionally neutral or even acid. In chemical composition it corresponds * Edinb. Med. and Surg. Journal, vol. 57. pi. 7 fig. 2. PRODUCTS, ADVENTITIOUS. 145 very closely with the serum of the blood, — its essential protein -ingredient being albumen in the state of albuminate of soda. As various degrees of inspissation of the fluid occur, the ratio of the solid ingredients to the water varies within rather wide limits. Accidental constituents are bihphaein, urea, and haematin. Fat is always present ; and scales of choles- tein (visible to the naked eye) are not very unfrequent, especially in dropsy of the tunica vaginalis. Epithelial cells are to be seen in small quantities (and we have found these calcified) : there is no reason to believe that an excessive quantity of epithelium is necessa- rily a part of the disease, though in some cases milkiness or a puriform look may be caused by their extreme abundance. Pus and blood corpuscles may be accidentally present. The fluid of true dropsy is distinguishable by the deficiency of developmental power : it never forms a blastema for cell- growth ; nei- ther is it capable of spontaneous coagulation. "But in some rare instances fibrin escapes along with the serum of the blood, — and this in notable quantity. The fluid then becomes coagulable ; but it is a mystery why (some- times occurring within the body) its coagu- lation sometimes does not occur until some hours after its removal from the body. We have seen the contents of the plem-a, perfectly fluid when first exposed, become distinctly clotty within an hour and a half: similar oc- currences have been witnessed by others. When coagulation takes place within the body, the coagulum may probably act as abkistcma. The cause and mechanism of this escape of fibrin from the vessels, and its relationship to inflammation are utterly unknown. In a former place (p. 93) we have spoken of the occasional excretion of fibrin w ith the urine. GROUP III. GASEOUS ADVENTITIOUS PRODUCTS. If the precise signification given to the term Adventitious Product be considered, it will be seen that gaseous matters are only truly ad- ventitious when foreign in nature to the textures producing them. Air entering veins lying within the suction-influence of the chest ; air swallowed; air entering the uterus and blad- der from without ; and air difiiised through the cellular membrane, serous cavities, or paren- chymatous organs, and derived from the air passages or alimentary canal, through a wound, ulceration, perforation or rupture of these ; consequently find no place under the present head. We shall here confine ourselves to a notice of gases produced by (a) local or ge- neral anti-cadaveric decomposition, and (6) an alleged process of secretion. (a) A man, aged twenty-five, died on the sixteenth day of continued fever (Peyerian type), and was examined by M. Bally eight hours after death. The body was soiled with blood, which had transuded through the skin of the thighs and scalp, and thei^e was uni- versal emphysema. The mesenteric glands contained gas which, like that in other parts VOL. IV. of the body, took fire and exploded, when brought in contact with the flame of a taper ; in burning it formed a tuft with a blue base and white apex, and appears to have consisted of proto-carburet of hydro- gen, one of the ordinary products of putre- faction, and is presumed to have been formed before death. (Art. Emphysema, Cyclopaed. of Surgery, vol. ii. p. 85.) Dr. Mouat (Ed. Med. and Surg. Journal, vol. liii. p. 427. 1840) has published a case in which gas was found in the cellular tissue of the right thigh, on the surface of the pericardium and pia mater, and in the right side of the heart and femoral vein. Accumulation of gas from de- composition of fluid in the pleura, pericardium, peritoneum, joints, and tunica-vaginalis, has been described by various persons : hydro- pneumothorax, however, it is to be remem- bered, without perforation of the lung, is cer- tainly of excessive rarity. {b) It occasionally happens, as was first, we believe, noticed by Dr. Graves, that at a certain period of the progress of pneumonia, the percussion-siizns of pneumothorax may be discovered. Within the last year we have had in our wards a most interesting case of pure and simple pneumonia, unattended with the formation even of dry plastic matter in the pleura, during the progress of which a perfect tympanitic note (quite distinct from an amphoric or tubular one) continued for some time producible over the affected lung. The only mode of accounting for it seemed by admitting the presence of air in the pleura, — and if such were the fact, that air must have been the produce of secretion. A sin- gular case is recorded by Sir F. Smith*, in which a secretion of gas from the skin ap- pears to have taken place. (c) It is not uncommon to find bubbles of gas in the veins of the pia-mater, and their presence is not easily explicable. If the gas be regarded as of putrefactive origin, the dif- ficulty is to explain why it occurs in bodies perfectly free from ordinary evidence of pu- trefaction, and why it is limited to those par- ticular veins. If it be regarded as natural gas of the blood extricated during life, how comes it, that the blood in that particular part only should present it after death, and how comes it that, if really extricated therey it had not been carried on with the circulating fluid to the heart? The quantity of gas is too small in such cases to admit of analysis, — else perhaps a comparison between it and the giises of venous blooti might throw some light on the matter. But next comes the curious fact that where there is least blood there is most i!)tra-venous air, — that is, where there is most of the pre- sumed cause, there is least of the presumed effect. It is, in fact, in persons, who have died from haemorrhage, that air has been found in greatest abundance in the veins. Lieutaudf relates the case of a girl who died * Dub. Med. Journal, vol. x\'iii. p. 457. t Hist. Anat. Med. Obs. o5. L 146 PROSTATE GLAND. suddenly in a state of syncope, after having been repeatedly bled, and in whom the cere- bral veins and choroid plexus v/ere found full of air. M. Rerolie* has published several cases of the kind, where profuse haemorrhage had existed ; in one of fatal epistaxis, the heart, arteries, and veins, contained large quantities of air. Another of these is ren- dered particularly remarkable by the fact that the gas (subcutaneous) took fire with slight detonation (as in M. Bally's case), and burned with a bluish flame ; here the patient had died of hasmorrliage after removal of a tumour from the back, and was examined six hours after death, the thermometer (Reaum.) mark- ing only + 2°. Similarly Dr. Graves has noticed emphysema of the abdominal parietes in a sufferer from frequent epistaxis. In all this there is much mystery. M. Rerolie conjectures that, in such cases, air is absorbed by the radicles of the pulmonary veins, — the air would then have no claim to be considered adventitious, and the hypo- thesis is, perhaps, not to be rudely rejected. ( Walter Hoyle Walshe,) PROSTATE GLAND. (Corpus glandu- losum ; UpoGTOLT^Cj Gr. ; die Vorsteherdruse, Germ. ; La Prostate, Fr.). — The prostate is a glandular body surrounding the neck of the bladder and beginning of the urethra of the male, deriving its name from its position in front of the vesiculae seminales. It is situated in the anterior part of the pelvis, behind and below the level oi' the symphysis pubis, posterior to the triangular ligament of the urethra, with which it is connected by a continuation of the latter with its capsule. It has the mem- branous part of the urethra in front of it, and somewhat below its level, and it rests upon the anterior surface of the middle of the rec- tum. The prostate is perforated by the ure- thra, two thirds of the gland are below this canal ; it inclines oblirjuely downwards and forwards from behind, its apex being situated rather below the base. In shape the prostate resembles a Spanish chesnut, or the ace of hearts on playing cards, and presents a base behind and an apex in front ; it is compressed from before back- wards ; its sides are convex, and its base is notched. From base to apex the prostate measures from an inch to an inch and a quar- ter; from side to side, from an inch and a half to two inches ; and from half an inch to an inch in depth from before backwards : a healthy prostate weighs five or six drachms. This measurement nearly accords with that given by Dupuytren, who devoted much at- tention to this subject, as having a most im- portant bearing upon the bilateral operation of lithotomy. A correct knowledge of the relations of this body to the adjacent viscera is of the highest practical importance. If, after the introduc- tion of a catheter through the urethra into the bladder, the finger be passed into the rectum, * Theses de Paris, Xo. 129. 1832. and carried forward, the bulb of the urethra is first indistinctly felt, behind which is the membranous portion; whilst beyond this, and still within reach of the finger, the prostate is perceived. In the empty state of the blad- der the outline of this body is usually distinct enough ; but when the bladder is over dis- tended with urine it becomes in a great mea- sure confounded with the posterior surface of this viscus, and cannot be easily distinguished. To obtain a good view of the connections of the prostate, a side view of the pelvis should F'g. 100. a, OS pubis ; h, ischium ; c, bladder ; d, ligaments of the prostate ; e, prostate gland ; /, posterior false ligaments of the bladder ; g, ureter ; h, vas deferens ; i, left vesicula seminalis ; j, rectum ; k, a small portion of levatorani. be prepared in the ordinary manner, by the removal of the left os innominatum, with the soft structures in inmiediate connection with it, leaving a small portion of the sym- physis and ramus of the os pubis, together with the spine and a part of the ramus of the ischium. In this manner the levator ani is first brought into view, at the upper edge of which is seen the point of division of the pelvic fascia into the vesical and obturator. The levator ani has no immediate connection with the prostate, for, although it gives it a general lateral support, it is separated from it by the vesical fascia. Internal to the leva- tor ani lie the vesical fascia and the levator prostatae muscle. The vesical fascia is con- tinuous w ith the pelvic, it passes inwards over the prostate, rectum, and bladder, inclosing these structures in separate sheaths. Thus the prostate gets a complete investment from it ; this covering is above continuous with the anterior true ligaments of the bladder, in front it is connected with the posterior layer of the deep perinaeal fascia, and beneath, the fascia passes between the gland and the rectum; thus the gland is completeh' invested by a fibrous capsule. This envelope incloses w ithin it the prostatic plexus of veins, and the blood-vessels and nerves of the prostate ; the veins are coniinuous in front with the dorsal PROSTATE GLAND. vein of the penis, and behind with branches terminating in the internal iliac vein. Many branches of the prostatic venous plexus are necessarily divided in the lateral operation for the stone ; and in old persons, from their in- creased size, they occasionally pour out so large a quantity of blood as to endanger the life of the patient. They often contain cal- culous concretions, to which the term phle- bolithes has been given. The following is the mode of connection between the prostate and the coats of the bladder ; the mucous coat is of course continuous from the bladder to the urethra ; the submucous cellular coat is firmly adherent to the capsule of the gland, whilst the inferior fibres of the detrusor urinas are arranged thus, the longitudinal fibres split into two layers, one, the thickest, adheres ta the submucous cellular coat of the bladder just behind the prostate ; and the other, thin and indistinct, is implanted into the base of the gland itself. Harrison has described a long, delicate, and distinct band of muscular fibres as entering the notch in the base of the gland, beneath the uvula vesicae and middle lobe, into which it is sometimes inserted ; but it can frequently be traced nearly an inch further to be inserted into the veru montanum.* 1 can- not satisfy myself of the existence of any muscular fibres at the under sui'face of the prostate. On either side of the gland we perceive a muscle, the levator prostates. It is frequently confounded with the anterior edge of the levator ani, from which however it is occasionally separated by a layer of cellu- lar tissue. It arises from the posterior part of the symphysis pubis by a tendinous slip, and its origin extends for a short distance backwards from the anterior true ligament of the bladder of the corresponding side ; as it descends, its fibres spread out over the side of the prostate, and are inserted into the under part of its capsule its use is to sup- port the gland, and by compressing it laterally to assist in the evacuation of its ducts. The prostate rests on the anterior surface of the rectum, a thin layer of fascia passing under- neath the gland and the vesiculae seminales. Behind the prostate are the vesiculae, which diverge from each other as they recede, and are in front received into the interval between the lateral lobes, their anterior extremities are placed beneath the third lobe ; the vasa defe- rentia run on their inner side, and the common ejaculatory ducts pass upwards in a curved direction, between the lateral and middle lobes, to terminate by the side of the sinus pocu- laris. The anterior surface, which is grooved by a shallow longitudinal depression, is attached to the back part of the symphysis pubis on either side by two ligamentous or tendinous bands, which are continuous with the cap- sule of the gland below, and above with the true anterior ligaments of the bladder ; * See Art. Bladder, vol. i. p. 381. ; 'and for de- scription of the arrangement of the circular fibres, see the same article. they are termed the Ugamenta puho-jnosta- tica media et lateralia ; they serve to support a,bladder ; h, section of the middle lobe of the pros- tate ; c, left vas ejaculatorium ; d, left vas deferens. the prostate and sling it to the pubis, thus contributing to the support of the neck of the bladder. The posterior surface of the pros- tate is smooth and is traversed by a lonerhaps more probable, to the presence of pepsine. Casein has been found in some of the animal fluids besides milk : the saliva, the bUe, pan- creatic juice, and perhaps the blood, all con- tain it in more or less notable quantity. It affords another instance of the admirable adap- tability of this interesting class of compounds PROTEIN. 169 very similar to that already mentioned when speaking of albumen : in the milk, which is the sole food on which the young of most ani- mals subsist, no other protein compound has been detected ; but no sooner has it become the food of the young animal which it is in- tended to nourish, than it is for the most part converted into fibrin and albumen, thus fur- nishing blood and muscle, together with most of the other tissues of the body, which, though less directly, are scarcely less certainly products of the decomposition of this substance. The composition of casein is represented by the for- mula ^3 10 Oj^o S, or ten equi- valents of protein united to one equivalent of sulphur, thus differing from fibrin and albu- men in not containing any phosphorus. There is another modification of protein, very similar to casein in its properties and composition, which has been called both glo- bul'm and crystalline, from the circumstance that it is found surrounding the blood globules and also in the crystalline lens of the eye. It appears to contain no phosphorus and less sul- phur than casein, and is composed, according to Mulder, of fifteen equivalents of protein united to one of sulphur. The form in which protein exists in hair, horn, nails, and the epidermis, and called by Simon kemtine, has been but imperfectly ex- amined. That these substances are composed chiefly of protein is proved by the circumstance that if a solution of them be made in caustic potash and neutralized with acetic acid, a co- pious precipitate of protein is thrown down. It is probable that other modifications of protein will hereafter be found to exist in the animal body, but those which I have now described are all which have hitherto been detected. The animal body, however, is not the only source from which protein and its compounds are to be obtained. The researches of modern chemists have led to the interesting fact that they exist in the vegetable kingdom also, and that they are there so extensively disseminated that not a leaf, a seed, or a twig, in any of the various tribes of plants, is free from them ; and it is highly probable that the wdiole of the protein compounds constituting the bodies of animals are derived from plants. In the pre- sent state of analysis it is perhaps too much to say that the forms in which we find protein in vegetables are absolutely the same, with regard to the minute quantities of sulphiu' and phos- phorus, as those found in animals ; but as far as we are able to judge from similarity of pro- perties, we may safely divide them in the same way as the analogous animal principles ; viz. into vegetable fibrin, vegetable albumen, and vegetable casein. They all yield, when heated with strong hydrochloric acid, blue or purple solutions; and when they are digested with a solution of potash, and neutralized with acetic acid, protein is invariably produced. Vegetable fibrin is found most abundantly in the seeds of the cerealia, as wheat, oats, &c. : it is also found dissolved in the juice of most plants, especially that of grapes, carrots, tur- nips, and beetroot, from which it shortly sepa- rates in the form of a flocculent precipitate when taken from the [)lant and allowed to stand. The readiest way of preparing it is to knead wheaten flour into a paste with water, and then w-ash it on a linen cloth with a stream of cold water until the whole of the starch is removed, which is known by the water passing through quite clear : the viscous mass which remains on the cloth is subsequently purified by washing with alcohol and ether, in both of which the fibrin is insoluble. When dry it is a hard horny-looking substance, semitranspa- rent, without taste or smell, and sufficiently heavy to sink in water, in which it is insoluble. Phosphoric and acetic acids readily dissolve it ; and it is reprecipitated in the form of white flocks from its acid solution by carbonate of ammonia and ferrocyanide of potassiiuii, and yellowish by tincture of galls ; it is also preci- pitated by bichloride of mercury and some other metallic salts. It is perfectly soluble in solution of potash even when very dilute, and if the quantity of fibrin dissolved be large, the liquid loses its alkaline flavour. Vegetable albumen is found to exist very abundantly in the juices of most plants, and still more so in nuts, almonds, and other oily seeds, where it is usually associated with ca- sein. It may be easily recognized by boiling the expressed juice of any of the common cu- linary vegetables after the fibrin has separated, when it coagulates in a manner similar to ani- mal albumen. It may be obtained in a tole- rably pure state by boiling the filtered juice of any of the Icguminoscs, and washing the preci- pitate with alcohol and ether. It closely re- sembles animal albumen in properties, and is distinguished from vegetable fibrin by its so- lubility in water, and from vegetable casein by coagulating when heated. Vegetable casein has also been called legu- mine, from the circumstance of its being found most abundantly in the Icguminosce, though it is by no means confined to that tribe of plants: it is also present in considerable quantity in company with albumen in most of the oily seeds, and in the juices of most nutritious vegetables. It may be obtained by the follow- ing process. Peas or beans should be soaked in moderately warm water for some hours until they are sufficiently soft to allow of their being mashed in a mortar : the pasty mass is then mixed with a large quantity of water, which dissolves the casein, and thrown upon a cloth to filter. The starch passes through the filter together with the solution of casein, and if allowed to stand, gradually subsides to the bottom : w^hen the liquid is clear, it is decanted by means of a syphon, and slightly supersa- turated with acetic acid, which detei mines the precipitation of the casein in an impure state, but readily purified by washing w'ith alcohol and ether. Vegetable casein resembles that obtained from milk in most of its properties ; gives the same insoluble skin when heated in contact with the air ; and is precipitated from its aqueous solution of alcohol and several of the metallic oxides : it is also thrown down by both vegetable and mineral acids, redissolving 170 PTEROPODA. in an excess of the former, except the acetic, and insoluble in excess of the latter. If a so- lution of casein be allowed to stand some time, lactic acid is gradually formed, which causes it to coagulate, and putrefaction then begins, which, if any sugar is present, determines in it the alcohohc fermentation. The various forms of protein which are found constituting the muscles, tissues, and solid matters of the blood of animals, are thus evi- dently derived from the vegetable kingdom ; that silent but ever active laboratory in which so much of the chemical economy of nature is carried on. From the gaseous matters of the atmosphere, more especially carbonic acid, ammonia, and watery vapour, the organic ele- ments, carbon, oxygen, hydrogen, and nitrogen, are derived ; and from the various saline ingredients of the soil, those inorganic sub- stances which are essential to the growth and well-being of mankind and of the lower ani- mals are readily abstracted by the absorbent fibres of the roots. Thus formed, plants con- stitute the source from which all living beings obtain the nourishment which is necessary to their existence, and of which the very sub' stance of their bodies is composed ; an arrange- ment which is most strikingly evident in the herbivora, because vegetables are their only food, but not less certainly in the carnivora, since the animal flesh which they consume is either that of the herbivora or of some ani- mals which have fed upon them. It is impossible not to admire the simplicity which pervades the whole of this vast scheme, in which we find so large a portion of the animal body composed of materials almost identical in composition, though differing so essentially in their use and applications. If one of these principles, albumen or casein for instance, be contained in the food in quantity insufficient for the requirements of the animal, it is readily supplied from one of the others by the addition or removal of a minute quantity of sulphur or phosphorus, both of which are always present; whereas, if this beautiful pro- vision had not been made, a large amount of disease and suffering would have almost neces- sarily ensued. Moreover, had the task of ela- borating these highly complex principles from more simple ingredients devolved on ani- mals themselves, much complicated machinery would probably have been requiretl, which w^ould have added unnecessarily to the com- plexity of the body, and consequently to the sources of physical derangement. [Since the above has been in type, some researches, which are still in progress, have thrown a doubt upon the exact composition of protein, and indeed rendered it uncertain whether it can be obtained in a state per- fectly free from sulphur.] Bibliography. — The following books may be mentioned as containing the fullest descriptions of protein and its compomids, together Avith other branches of physiological chemistry : — Simon, Hand- biich der angewandten medizinischeu Chemie, of which a translation has been published by the Sy- denham Society. Liehig, Traite de Chimie orga- nique, tom. i. & iii. Liebig's Animal Chemistry, translated by Gregor}'. Mulder, Chemistry of vege- table and animal physiology, translated' fi-om the Dutch by Fromberg ; and Dumas, Traite de Chimie appliquee aux arts, tom. ^-ii. & viii. Besides these many detached papers of gTeat value will be foimd in the later vohmies of the Annales de Chunie et de Physique ; Annalen der Chemie mid Pharmacie, by Liebig and Wohler ; Poggendorff's Annalen der Physik und Chemie ; Philosophical Transactions, Philosophical Magazine, &c. (./. E. Bowman.^ PTEROPODA (Gr. irrepov, a wing, iroZs, a foot ; Fr. Pteropodes ; Lat. Mollusca j^in- nata). — An order of Molluscous animals es- tablished by Cuvier, and named in accord- ance with his arrangement of the Molluscous division of the animal kingdom, from the po- sition of their organs of locomotion, which in the creatures we are about to examine is very remarkable. All the animals belonging to the order are marine, and in some regions of the ocean crowd the surface of the sea at certain seasons in immense numbers, swim- ming by the aid of two muscular expansions resembling fins, which are attached to the op- posite sides of the neck, and serve as paddles, although, in the language of Natural History, named feet. Notwithstanding the multitudes of indi- viduals belonging to this group, which are said to swarm both in the polar regions and in tro- pical climes, the number of genera at present ascertained to exist is very limited, and such is their minute size and the delicacy of their structure, which precludes the possibility of studying them, unless in a fresh state, that, up to a very recent period, their anatomy was imperfectly understood, and, doubtless, much remains yet to be achieved by those who may be favourably situated or investigating them more closely. The characters which they present in common, and by which they are separated by naturalists as a distinct group of Mollusca, are the following : — Their bodies are free, and organized for natation ; they are fur- nished with a distinct head, but possess no locomotive organs, except a pair of lateral fins. Genera. Clio {fg. 108). Hyalea {Jig. 114). Pneumoderma {fg. 115). Cymbulia. LiaiACINA. Cleodora. AtLAxNTA. M. d'Orbigny, in a memoir read before the Academy of Sciences in Paris*, gives some interesting particulars relative to the organi- zation and habits of this remarkable class of molluscous animals. They are met with in all seas, under the equator as well as in the * Vide Ann. des Sciences Xat. for 1835, p. 189. PTEROPODA. 171 vicinity of the polar circle ; and, being emi- nently constructed for a pelagic life, never approach the shore. They are all, moreover, nocturnal or crepuscular, voyagers agreeing that they are never to be seen during a clear day when the sun shines brightly ; but towards five o'clock in the evening, when the weather is cloudy, two or three species begin to make their appearance at the surface of the water, generally belonging to the genus Hyalea. As soon as twilight begins, large quantities of small CleodorcB, HijalecB, and AtlantcB may be caught ; but the larger species only come to the top when night has set in ; at which time only the Pneiimodermas, the Clios, and the large CleodorcB can be procured. Certain species indeed only approach the surface on very dark nights, as, for example, the Hyalea balanfium. Very soon all the smaller species again gradually disappear, as do the large ones a little later, and towards midnight a few stragglers only of different kinds are to be met with. At sunHse not a single Pteropod is to be seen, either at the surface, or at any depth to which the eye can penetrate. Each spe- cies, in fact, seems to have its appropriate hours, or rather its appropriate degrees, of darkness. M. d'Orbigny supposes, from these habits, that each species lives at a certain depth in the water which is proper to it, and where it is consequently exposed to a diminution of hght proportionate to its distance from the surface. Every species, therefore, will only come to the top at that period of the twenty- four hours when the obscurity approximates to that to which it is accustomed in its usual situation while the sun is above the horizon, mounting gradually upwards as the light of day diminishes. If the Pteropoda remained all night at the surface of the sea, there might be reason to think, as M. Rang supposed, that they ascend at sunset for the purpose of ob- taining food or fresh air in the most super- ficial strata: of the ocean ; but as these could be procured at all hours, it seems more pro- bable that it is the light which thus regulates their movements. There is reason to suppose that each spe- cies of Pteropod remains during the whole year in the same regions of the ocean. These regions are of different degrees of extent, and currents doubtless tend to enlarge their boundaries ; probably to this cause must be attributed the extensive difflision of certain species met with in all climates ; whilst others of larger size are only found in the torrid zone, and others again of equal dimensions are peculiar to cold climates. A table appended to the Memoir of M. d'Orbigny assigns the limits between which each species has been found, and its nocturnal or crepuscular habits. From this table it appears, that of twenty-nine species of Ptero- pods known to the author, fourteen are met with both in the Atlantic and Pacific oceans, whilst eleven are proper to the Atlantic and four to the Pacific ; of these seventeen are altogether nocturnal in their habits, and only eleven crepuscular. The Pteropoda swim in a very peculiar manner. Their cephalic fins are only able to suj^port them by a constant repetition of rapid movements, resembling those of the wings of a butterfly. These fins are kept in motion continually ; and, according to the di- rection of their stroke, the animal advances horizontally, or mounts or descends, the body remaining all the time either in a vertical position or slightly inclined. Sometimes they keep spinning round without changing their place, or even keep at a certain height in the water without any apparent exertion ; but this power of remaining motionless has only been observed in a small number of species, the butterfly-movement of the wings being most commonly resorted to. If while they are thus in motion, the appearance of any strange body or even a sudden shock given to the vessel in which they are contained, causes them alarm ; their wings fold upon their bodies, or in some species are entirely withdrawn into their shell, and the animal sinks rapidly to the bottom of the vessel. Most probably, when at liberty, as soon as the creature has sunk to a sufficient depth to ensure safety, it again unfolds its wings, and sustains itself in the water instead of allowing itself to go quite to the bottom. The Hyalea and Cleodora swim with the greatest rapidity, in Pneumoderma and Clio the movements are less vivacious. The larger Pteropods seem to feed prin- cipally upon smaller species of their own class, as well as upon the minute crustaceans that swarm in the seas they frequent. Clio. Integument. — The skin of the Clio is not smooth, but studded with numerous little wart-like eminences, causing a roughness, which is in direct relation with the red colour of the integument, and is consequently most conspicuous near the extremity of the tail. Both the roughness and the red colour in- deed are produced by the presence of a mul- titude of little cavities or sacculi filled with an oily red pigment, the pointed ducts of which project externally. These pigment-sacs are not only most abundant near the extremity of the tail, but in that part of the body are of larger size than elsewhere : they are all flask-shaped, opening upon the surface of the body by a narrow neck, while their larger ex- tremity is imbedded in the subcutaneous cel- lular tissue. Beneath these larger pigment- sacs smaller ones of a similar description are perceptible, much smaller in their dimensions than the preceding, and in many places where the larger ones are deficient, the smaller pig- ment cells are proportionately more nume- rous : both kinds are filled with the same oil- like colouring material, and are apparently comparable to simple mucous follicles, only their secretion is of a more oily character. With the exception of the pigment cells, the integument of the living Cho is quite trans- parent, but after being kept in spirits of wine, its transparency is considerably diminished ; in its 172 PTEROPODA. substance, muscuiar fasciculi are perceptible, the direction of which is principally towards the crucial muscles of the fins. Upon the dorsal region of the body, these tegumentary muscles first become distinct at the trans- verse constrictions above referred to. These constrictions disappear as soon as the skin is cut through, and the inner layers of the dorsal region then appear quite lax. In this way, indeed, the existence of transverse fas- ciculi of cutaneous muscles is rendered evi- dent, even when their presence cannot be proved by direct observation. Jn many places, the cutaneous muscles are still more complex in their arrangement, more particularly in the neighbourhood of the eyes. In the head, and partially also in the neck, where a firmer connexion between the skin and the general muscular strata of the body exists, an expansion of the proper cutaneous muscles is with difficulty to be demonstrated. Fig. 108 (1 to 6). 1. Clio Borealis, seen from the ventral aspect, the head-cowls shut together. 2. The same ; the head-cowls turned back, and the cephalic and generative apparatus displayed. 3. Details of ditto. 4. Clio borealis with the head cowls closed, seen from the dorsal aspect. 5. Side view (right) of the same, the fins cut off at their roots. 6. Details of ditto. {After Eschricht.) The nerves of the integument are easily traced in fresh specimens on account of the transparency of the skin. The most con- spicuous are two large cutaneous nerves run- ning on each side of the body, which ramify upon its lateral and ventral aspects. Immediately beneath the skin is a layer of cellular tissue, which is very different in dif- ferent regions. In the hinder part of the body it exists in great abundance, and in it, as already stated, the large pigment cells are imbedded, so that in this region the skin is very easily separated from the muscular strata beneath. It is most abundant likewise in the region of the heart where the urinary bladder is situated. In the fins, this cellular mem- brane is more scanty, and in the regions of the neck and head, it is so dense that here the skin can only be raised with difficulty. In specimens that have been kept in spirits, the subcutaneous cellular tissue is very gene- rally infiltrated with fluid so as to give the appearance of a cavity existing beneath the integument, the boundaries of which are cir- cumscribed by those parts where the skin is most adherent to the subjacent tissues, or where the cutaneous muscTes interlace with each other. Muscular system. — The muscles of the Clio borealis are chiefly disposed in a single layer, situated beneath the subcutaneous cellular tissue, that encloses the whole hinder part of the body as in a bag, which, however, in the region of the neck and of the head, spreads out into separate fasciculi of muscle. This muscular bag is described by Cuvier* as being composed of very conspicuous longi- tudinal fibres, derived from two principal fas- ciculi attached to the sides of the neck, the effect of which will be to shorten the whole body, and make it assume a form approxim- ating to the spherical. In fresh specimens preserved in spirits, the muscular bag in question is easily visible through the skin ; but in the living animal, it is most likely it- self transparent, and in old specimens cannot be seen on account of the opacity of the ex- ternal integument. The muscular fibres com- posing this sheath, do not by any means run straight and undivided from behind forward, but, on the contrary, interlace with each other, so as to form an expansion in which the lon- gitudinal fibres are the most conspicuous. From the neck forwards, these muscular bands become more precise in their arrangement. At the sides of the body, they separate from each other so as to leave a space both be- hind and in front, in which the muscular layer is deficient; the dorsal and ventral fasciculi becoming more and more detached as they advance forwards, leaving a wide opening in the muscular sheath, which near the head gives passage to the lateral fin, and behind this for the pair of large cutaneous nerves, also on the right side, close to the fin, for the common opening of the male and female generative ap- paratus, and, a little behind the exit of the two cutaneous nerves, for the anus. In its posterior corner lies the pericardium also on the right side but more deeply situated. These different parts, as they issue through the muscular opening of the right side, are further embraced by muscular fasciculi, which * Memoire sur le Clio, p. G. PTEROPODA. 173 run transversely from the dorsal to the ventral aspect of the body bounding and separating their orifices. Locomotive Apparatus. — The locomotive ap- paratus of the Pteropoda is constructed upon most peculiar principles, consisting of a pair of fin-like expansions attached to each side of the neck of the animal. These fins, or, as they are commonly called, wings in the Clio have a very remarkable struc- ture, the two being continuous with each other, through the intervention of a central part, which extends transversely across the neck of the animal, so that the lateral expansions are only the free extremities of the same organ, the whole apparatus representing, \\ ith curious exactness, the double paddle used by the Greenlanders in na\ngating their light double- pointed canoes (Kajaks). The entire appa- ratus is muscular, and consists of two layers, precisely similar in their structure, which, at their margins, overlie each other, but are only connected together by means of cellular tissue. The course of the muscular fibres is shown in the annexed figure, representing the %^hole of the swimming apparatus removed from the body; in which the following parts may be distinguished : — a, the anterior or Fig. 109. Clio BoreaJis. Swimming apparatus detached- (^Afier Eschricht.) dorsal margin ; b, the posterior or ventral ex- cavation ; c c, the posterior, transparent, tri- angular lappets which bound the (in ; d d, the posterior outer border ; ee, the posterior inner border ; o, the central portion which traverses the neck ; m 7n m m, commencement of the free portions of the fins. In the cellular membrane interposed be- tween the two muscular layers of the fin ap- paratus, four or five large nerves are seen to run a tortuous course, and to divide into in- numerable fibrillae. Eschricht likewise ob- served a considerable blood-vessel derived from the ventricle of the heart (not from the auricle'), mounting up and dividing to supply each fin. Respiration and Circulation. — According to Cuviers views the fins of the Pteropoda have been very generally regarded as performing likewise the functions of branchiae. " Their surfaces, seen with the microscope, present a net-work of vessels, so regular, so close, and so delicate that it is impossible to doubt their office : their connection with the internal ves- sels and the heart, moreover, confirms this idea." * Cuvier's opportunities of investi- gating this point of their anatomy were, how- ever, very limited ; a single specimen only, and that long kept in spirits of wine, having been at his disposal. Eschricht's researches do not at all confirm this view of their nature ; and it appears clear that Cuvier mistook the net- work of muscular fibres represented in the preceding figure for vascular ramifications. * Cuvier, Me'm. sur le Clio. The vessel likewise called by Cuvier the branchial vein," and which he regarded as re- turning the blood from the branchice to the auricle of the heart, Eschricht assures us, does not communicate with the auricle, but is de- rived from the apex of the ventricle so as tJ be evidently arterial, and not venous, in its nature. With regard to the connexion which exists between the fin-apparatus and the body of the Clio, it would appear that its central muscular basis passe^i directly through the neck, and is only attached to the surrounding parts by nerves, vessels, skin, and cellular membrane. Xervous system. — The nerves of the Clio are very easily traced, seeing that they are not only of considerable size, but are likewise con- spicuous, on account of their pale red colour, at least while the specimens are tolerably fresh. The oesophageal ring lies in the neck above the centre of the fin-apparatus, and lodged in its dorsal excavation. It is composed of eight large and two small ganglia. Each gang- lion is surrounded by a transparent invest- ment, and is ven»- e\-idently composed partly of a reddish and partly of a white nervous substance. Of the eight larger ganglia of the circum-oesophageal ring the two anterior (fig. 113. 30, 1) are situated close together, upon the dorsal aspect of the oesophagus ; the two posterior {fig. 113. .30, 4) are likewise close together, but beneath the oesophageal tube. Ot' the four intermediate ganglia, two are situ- ated close together on each side of the oesoph- agus (fig. 1 13. 30, 2, 3), so that when viewed 174 PTEROPODA. superficially, either from the dorsal or ventral aspect, they have the appearance of forming one elongated mass. By means of a nervous band which connects them, the eight ganglia form a doable ring, seeing that the two lateral pairs of ganglia are, as well as the inferior, brought into communication with each other through the intervention of a cross branch which runs beneath tiie oesophagus. In addition to the eight ganglia above men- tioned there are likewise two small nervous masses (Jig. 113. 30, 5), situated one on each side of the anterior pair, with which they are connected by short nervous branches. All the nerves given off from these centres seem to proceed from the ganglia nearest to their place of destination. From the anterior pair are derived all the nerves supplying the parts of the head and the eyes. From the lateral pairs the nerves of the fins are prin- cipally given off, while the posterior pair fur- nishes nerves to all the hinder parts of the body. Eijes. — The eyes in Clio are situated upon the dorsal aspect of the body, in the constric- tion which constitutes the neck. In this situation the skin is drawn deeply around them, so that they seem to be lodged in spe- cial depressions appropriated to receive them. Each eye (fig- 113. 31) has somewhat the shape of a bent cylinder, the two ends of which are of a spherical form. The external spherical ex- tremity of this eye, which is transparent, and constitutes the cornea, stands prominently above the level of the skin. By transmitted light it is not difficult to distinguish the con- struction of the interior. The middle third of the cylinder is generally of a dark colour, whilst the anterior and posterior extremities of the cylinder are comparatively transparent ; but, probably, in the recent animal, the dark pig- ment extends back as far as the hinder end — anteriorly, it is easy to perceive the existence of a transparent lens ; but from the small size of the organ, it is difficult to make out their structure more completely. In connexion with these eyes, delicate muscular fasciculi may be traced radiating in different directions, which would seem to have the office of turning the eye-ball towards any particular object. The only other special organs of sensation possessed by the Clio are the tentacula ; but these will be best described in connexion with the head to which the}' are appended. Head-cowls and Tentacula. — The structure of the head of Clio is very remarkable ; and, in its general characters, cannot be more ap- propriately described than in the words of Pallas. * " Caput contractum subgloboso- didymum est, lobo vel utroque vel aiterutro, imo quandoque neutro, antice papilla carnea (tentacidum) acuta, mucronata. Qui lobi sunt propne praeputia duo {the head-cowls) crassa, carnea ; hemisphaerica, contractilia, basi coad- unata, e quorum interiore latere emergunt tentacula (head-cones) tria carnosa, conica, * Spicelegia, x. p. 28. lequalia quae ori utrinque adstant et contracta in praeputio tota delitescunt." -P-'g. 110 (8 to 13). Anatomy of Clio. 9. Transverse section of tlie ventral fasciculi, as they pass through the nerve surrounded by the mus- cular collar (v). 10. Head of Clio, with the cowls half expanded, showing the conical cej^halic appendages (s), and one of the tentacula (k) protruded. 11. Head of Clio, cowls closed, and the left ten- tacle protruded. 12. The same seen from above. 13. The same, the cowls being -uadel}^ separated so as to display the opening of the mouth. (After Eschricht.) The above description will, however, be better understood by a reference to the ac- companying figures, in which the structures above mentioned are delineated on a large scale. In fig. 110. II the head is represented, seen from the ventral aspect with the head-cowls (a, b) closed together, concealing all the other organs except the tentacula, one of which (k) is seen protruding through an opening in the left cowl, that of the opposite side being re- tracted— while in fig. 110. 10 the head-cowls are shown partially folded back, so as to dis- play the conical appendages (head-cones) which the cowls enclose and protect. Each of the cowls (lobi, Pallas ; biicccB, Fabricius) seems, when more closely ex- amined, to be composed of two spherical parts intimately conjoined, of which the anterior (fig. 110. 1 1, a a) is the smaller, and the posterior {h b) the larger. The posterior spherical por- tions are continuous with each other ; they enclose a large cavity, which is, in its widest part, filled up by the penis ; but, in its nar- rower and median part, contains the parts of the mouth — the oesophagus and the saUvary apparatus. The smaller or anterior spheres, on the contrary, are only produced by the folding of the skin over the head-cones, and disappear when these organs are protruded. In the fore part of each of the anterior sphe- rical portions of the cowl is a little flat sur- ftice, in the middle of which may be observed PTEROPODA. 175 either the tentacle { fig. 110. 10 and 11,/.), or the orifice (^g.UO. 12, /), through which it is protruded : tiie two flat surfaces are separated from each other when the cowls are closed by a longitudinal fissure ), the margins of which form two prominent lips (o o). The lateral tentacles {k) are cylindrical, smooth, and terminated by rounded extremi- ties. They are hollow, and in their interior, three longitudinal bands of muscle and a nerve of considerable size are distinguishable, so that they can be retracted in the same manner as the horns of a snail, nothing re- maining externally to indicate their position, except the hole through which they are pro- truded. When thus inverted the tentacles are found lodged in the cavity of the head, with their apices directed inwards. The two smaller spheres of the hood or cowl are separated from each other by the longitudinal fissure {fig. 1 10. 1 1), which Fabri- cius, very inappropriately, called the mouth, although, at the same time, he was acquainted with the real mouth, and recognised it as such. This vertical fissure occupies the entire top of the head, and is continued for some distance both on its upper and under surface, or, more properl}' speaking, the real head is buried deeply in the interspace be- tween the two cowls, and when these are sepa- rated from each other, the following parts are seen situated between them : in the centre of the floor of the fissure is the vertical opening of the mouth {fig. 110. 13, u), between which and the borders of the hood {q), are the cres- centic spaces (r), in which are situated the conical appendages to the head already men- tioned, and which are represented protruding from between the margins of the hood in fig. 110. 10 {s). Conical Appendages to the Head. — The co- nical append^iges to the head (Kopfkegel, Eschricht), when fully expanded, form a kind of star round the mouth {fig. 108. 3, s), and were erroneously styled by Fabricius " soft teeth" (" suntque dentes hi molles subcrus- tacei"). It is to Eschricht we are indebted for a knowledge of the real nature of these wonderful organs, the structure of wdiich is unparalleled in the animal creation. It has been already noticed that these conical bodies are of a red colour in the recent animal, and, when they are protruded, it is easily discover- able with a lens that this colour depends on the presence of numerous separate coloured points distributed over their surface. When still further magnified, these points show themselves as closely aggregated spots, ar- ranged with great regularity upon the exterior of the cone. Upon a rough calculation there may be about three thousand of these spots upon each conical appendage, each of which, when closely examined, under favourable cir- cumstances, assumes very much the appear- ance of the polype-cell of one of the Sertularian polypes, and exhibits a structure which is truly admirable. Each little spot consists, in fact, of a transparent sheath, enclosing a cen- tral body, composed of a stem terminated by a kind of tuft, which last can be protruded at times beyond the margin of the sheath. When viewed laterally {fig. 1 1 1. 14) it is appa- rent that this central body consists of several filaments or tubes, every one of which ex- pands at its extremity into a dilated portion, terminated by a little disc {fig. 111. 15), and about twenty of these are enclosed in each sheath. The conical appendages to the head of a single Clio are, therefore, furnished with (20X3000X6) about three hundred and sixty thousand of the stem-supported discs in question. F^. Ill (14 to 21). Clio Borealis. 14. One of the 3000 prehensile organs with which each of the six conical appendages to the head is furnished. Magnified 300 diameters. 15. An isohited sucking disc from the above. Magnified 900 diameters. 16. The head and neck laid open by a longitudinal section, shoAving two of the conical appendages and the penis, in situ. Magnified 5 diameters. 17. Longitudinal section of the head along the mesial line. 18. to 21. Pharynx and oral apparatus. Magni- fied 7 diameters. {After Eschricht.) As relates to the internal structure of these conical organs, Eschricht ascertained that they 176 PTEROPODA. are hollow, and that their cavities communi- cate with the common cavity of the head : they have likewise their proper muscles, and each receives a large nerve derived imme- diately from the anterior supra- oesophageal ganglion. As to the use of this elaborate apparatus, there is still room for speculation. Captain Holboll, although he frequently ob- served them porrected, while the creature was swimming, never saw them employed as suckers or instruments of prehension ; never- theless, it seems impossible to doubt that such is their real office, when we reflect upon their remarkable structure, and further take into account their situation, so completely analo- gous to that occupied by the sucking discs of the Cephalopoda, and still more closely re- sembling the cephalic appendages of Pneiimo- derma. It is, therefore, extremely probable that these organs are employed for holding to foreign objects at the bottom of the sea, and that the great number of the sucking discs is in correspondence with the power possessed by the Cho of crawling about upon uneven surfaces. The mouth of the Clio is a vertical fissure, that is easily displayed by slightly folding back the head-cones (fig. 110. 13, m). Its margins seem to enclose some calcareous substance, which, in specimens preserved in spirit, is of a chalky whiteness. Numerous muscular fasci- culi surround this opening, which, when ex- panded, has somewhat of a triangular form, so that during life the mouth can be forcibly opened by the radiating muscular fasciculi that surround it. In the cavity of the mouth there may be observed, on each side, a round fossa, in which can be seen projecting, even with the naked eye, a hard shining substance, first noticed by Pallas and Fabricius, who re- garded these bodies as simple teeth. Closer inspection, however, reveals them to have a very curious structure, which is, perhaps, unique, each consisting of a bundle of about thirty gold- coloured, crooked, stifle and sharp hooks {fig. 112. 22, w), derived from a common base (x), and forming a pair of lateral jaws, wherewith the creature seizes its food. In the middle of the ventral aspect of the cavity of the mouth there is, moreover, a prominent tongue-shaped organ, which, when moderately magnified, may be seen to consist of two lateral bands of a black colour, which are united in the middle line, and which are covered with an immense number of extremely minute teeth, that will be more particularly described hereafter. The pharynx, when ex- amined from above, is somewhat lyre-shaped : it is composed of two lateral branches (fig. 111. 19, i), the posterior ends of which are joined by a convex central portion (z). The tube of the oesophagus is not prolonged imme- diately from its hinder extremity, but seems to arise from the hinder wall of the pharyngeal cavity {fig. 111. 17 and 21, e). The nerves of the pharynx arise from two ganglia {fig. 111. 18, 20, ?/) situated imme- diately behind it, in conjunction with the an- terior ganglia of the circumoesophageal ring, and which inferiorly are connected together by strong branches of intercommunication anil from which nerves radiate laterally to supply the surrounding parts. The thin ducts of the salivary glands {fig. 1 11. 17, 18, 19, and 20, g) terminate above these ganglia opening into the cavity of the mouth in the immediate vicinity of the tongue. The pharynx, when viewed with a lens, and still more when examined under the micro- scope, resembles, very closely, the gizzard of a gallinaceous bird, the resemblance consisting in the great strength of its muscular parietes. Each lateral portion {fig. 111. 18,0 is a small curved cylinder, the outer wall of which is entirely muscular. The fasciculi are princi- pally arranged in two layers, the fibres crossing each other. On opening one of these muscular capsules, by means of a fine pair of scissors it is found to contain, in its interior, a cylin- drical body made up of several parts. At its anterior extremity are situated the lateral teeth above alluded to (/g. 111. 19, and /g.ll2. 22, v). These are arranged in parallel arches, in such a way that their points all attain the same height, notwithstanding the great difference in their length, the posterior {exterior) tooth [fig. 112. 23, a) being far the longest ; while the an- 12 (22 to 24). CUo JBorealis. 22, 23 a, 23 b. Dental apparatus, magnified 28 diameters. 24. Lateral view of the free portion of the tongue, magnified 130 diameters. {After Eschricht.) PTEROPODA. 177 terior (interior) (23, b) is the shortest of the series. The stem upon which these are fixed (22, w) is sloped off in the same pro- portion, and has a somewhat triangular shape. When crushed under the microscope, it is found to consist entirely of muscular fibres ar- ranged with considerable regularity, and prin- cipally disposed in two opposite directions, so that they cross each other ; and doubtless a part of their office is to raise and depress the individual teeth, implanted upon the common stem. The hinder portion of the cyUnders (x) containing this extraordinary dental apparatus, is muscular, and composed of longitudinal fas- ciculi, by the aid of which the stems that sup- port the teeth are retracted, their protrusion being effected apparently by the conjitruction of the capsules themselves. The manner in which the Clio makes use of these teeth may, therefore, be inferred from their anatomical arrangement. The cylinders wherein they are lodged are so much bent (Jig. 111. 18, 19, i), that when the two dental organs of the oppo- site sides are protruded the apices of the teeth with which they are armed must meet together outside the mouth, and when in this condition the teeth of each organ are widely separated and spread out, they will form, as it were, a couple of long combs (19, i^), and evidently perform the functions of a pair of tenacious jaws. The tongue may be divided into two por- tions ; the one free, and the other fixed, studded with a number of booklets that can scarcely be estimated at fewer than from six to eight hundred, the disposition of which at once indicates their office to be to facilitate the propulsion of the food into the oesophagus, as is the case in the Cephalopods and various other Mollusca. The oesophagus is, for the greater part of its length, surrounded by the two salivary glands, which extend quite into the abdominal cavity, where the}' are connected to each other, and to the liver by lax cellular mem- brane. The stomach is a mere dilation of the oesophagus, and is entirely embedded in the substance of the liver. The latter organ appears, when examined superficially, to be entirely made up of a multitude of Aci7ii, each of which contains within it a cavity that communicates through a wide aperture with the interior of the stomach; and hence it re- sults, that, although the exterior of the liver is seemingly composed of large granules, the walls of the stomach are perforated all over with openings, leading into blind cavities, so as to have a completely cellular appearance. The intestine is a simple tube, passing straight from the termination of the stomachal portion of the alimentary canal to the anal orifice, which is situated on the right side of the neck immediately behind the correspond- I ing fin. I The course of the circulation in the Ptero- i poda has not been as yet completely made out. i In the Clio borealis, the heart enclosed in its i pericardium is situated on the right side of the i posterior end of the abdominal cavity just at VOL. IV. the point where the dorsal and ventral bands of muscle separate to form the wide lateral opening. The pericardium is pointed in front and broad behind : its walls are thin and trans- parent, but at the same time very strong. On opening the pericardium, the ventricle of the heart is seen to have the shape of a triangular pyramid with rounded angles, the apex of the pyramid being directed towards the head, whilst its ba^e is turned towards the hind part of the body. From the apex of the heart arises a large vessel, which immediately pierces the pericardmm, and supplies branches to the liver and to the internal organs of generation ; it then advances forward, and supplies the parts about the neck, more especially the lateral fins, and most probably is ultimately distri- buted to the head and its appendages. This vessel is evidently the aorta. Fig. 113 (25 to 31). Clio Borealis. 25. One of the lingual teeth, magnified 400 di- ameters. 26. INIale generative apparatus, removed from the body and unfolded. 27. Female generative organs displayed. 28. Convex surface of the testes. 29. One of the pigment sacs of the integument, magnified 120 diameters. 30. Nervous system, magnified 12 diameters. 31. One of the eyes, magnified 40 diameters. (After Eschricht.) Generative system. — The reproductive or- gans in the Clio boreahs occupy a very con- siderable portion of the abdominal cavity. 178 PTEROPODA. They consist, first, of an Ovary with its oviduct ; secondly of the " bladder; " and, thirdly, of the testis, upon which the bladder rests. The ovary {fig. 113. 21, p) is closely con- nected with the liver, in conjunction with which it occupies the dorsal region of the abdominal cavity, its anterior part being filled with the voluminous testicle. The ovary itself is nearly of a hemispherical shape, and is of a pale red colour, its surface having a granular appear- ance. When crushed under the microscope, all the granules of which it consists exhibit in their interior a little vesicle, together with a dark spot ; the former being, doubtless, the vesicle of Purkinje, the latter the germinal spot of Wagner. The oviduct {q) is tolerably thick, and arises from the middle of the flat surface of the ovary ; it immediately becomes consider- ably convoluted, so that it usually forms two loops, and, gradually becoming attenuated, reaches the " bladder " (a), which is situated in immediate contact with the testicle ; but, before joining the latter, it generally swells into a dilatation (/•) ; but this dilatation is not constant ; for sometimes Eschricht found two such enlargements ; whilst in other instances the oviduct retained the same diameter throughout its entire length : when present, the swelling was found to be solid, and pro- bably was produced by an accumulation of ova, coagulated by the action of the spirit in which the specimens had been preserved. The " bladder " {s) is situated very close to the surface of the testis, and appears to be supported upon a furcate stem, through the intervention of which it is partly in communi- cation with the oviduct, and partly with the testicle. This "bladder" is somewhat larger than the accidental swellings of the oviduct alluded to above, but, like them, was found to be solid ; and sometimes the mass was divisible into two flattened halves, a circumstance that would seem to indicate the non-existence of any cavity in the interior. The testis itself, in a recent specimen, is so large as to occupy a very considerable part of the abdominal cavity: it is nearly transparent ; and when portions of it are examined under the microscope, its substance seems to be en- tirely made up of minute tubes, connected to- gether by delicate membranous processes. Its external convex surface {fig. 1 13. 28) is convo- luted, so as to give it the appearance of being a hollow vesicle three times folded upon itself ; whilst its inferior concave surface exhibits under the microscope a reticulate appearance, something like that of the stomach of a ru- minant quadruped. The common outlet of the ovary, of the bladder, and of the testicle is short, but toler- ably thick. It mounts upwards, and ter- minates close behind the right fin, in the im- mediate vicinity of the anal orifice. On opening the cavity of the head, by re- moving its anterior wall (including the collar and the subjacent muscular layer), its contents are displayed as exhibited in fig. 111. 16. Im- mediately behind the contracted conical append- ages, and close to their hollow bases, is seen a long milk-white organ {b), which, in old specimens, is so extremely brittle, that it is generally broken in the dissection. Behind this, and close to the collar, lies a red sac- culus not easily to be displayed ; and, in the neck itself, immediately upon the collar, is situated a single loop, formed of the same white substance as b. On carefully unfolding these parts, they are found to present the structure displayed in fig. 113. 26, the transverse body (i) and the loop (c) constituting portions of the same viscus. The transverse portion is a canal terminating by a blind extremity (a), while the loop itself may be displayed as an ex- tremely attenuated canal {d) of a reddish colour, which, after several convolutions, opens into the red sacculus (g), and ultimately ter- minates in another short, but wider, tube (/ ) ; the common orifice of the sacculus and of the convoluted canal is a wide, longitudinal opening, situated in the cavity between the right fin, the head, and the collar. On cutting into this canal, it is found that the milky colour it presents is but slightly owing to the nature of its contents, depending principally upon the texture of its walls, which, w hen ex- amined under the microscope, are found to contain numerous granular bodies, which are apparently of a glandular character, united to- gether by a very thin and transparent mem- brane, the deficacy of which readily accounts for the fragility of the tube. The structure of the red sacculus {g) is not yet fully understood. Its walls are in some parts very thin, and on opening it, the tube (/) is seen to be continued through it. Eschricht was, at first, in considerable doubt as to the nature of this remarkable apparatus : he observed, however, that in several speci- mens, a portion of the sacculus was inverted and protruded externally in the shape of a long bow-shaped organ {fig. 114. 3, /i), along the cavity of which a delicate canal could be distinctly traced, the bow-shaped organ being manifestly the penis, everted in the same way as in many Gasteropod Mollusks, and the de- licate canal constituting the vas deferens. Hyalea. — The two fins are supported upon a fleshy neck, enclosed between the two lobes of the mantle {fig. 1 14. 3, c), which latter {fig. 114. 3, g, h, i, k) correspond accurately with the valves of the shell, beyond the edges of which they protrude all around, and which they cover with a thin epidermis. The position of the branchiae Cuvier ob- served not to correspond with what he had, erroneously, believed it to be in Clio, — namely, the surface of the lateral fins ; for in Hyalea he could not discover any vascular net-work in those organs, even with a microscope ; and thus indirectly confirms the correctness of Eschricht's views upon this point. He, there- fore, sought for them elsewhere, and, " on breaking the shell, he found them to be situ- ated between the two lobes of the mantle at the bottom of the outer space between them PTEROPODA. 179 on each side, so that the lateral fissures of the shell have apparently the function of admitting the surrounding element to the branchial organs. These latter are composed of little laminae, resembling those of patellae, phyllidia, &c., which surround the body so as to form a sort of elliptical belt, not placed transversely, but parallel to the course of the dorsal surface {fig. 1 14. 5, 6. p, r, s). The Fig. 114 (1 to 9). Anatomy of Hyalea. (^After CuvierJ) 1. The animal entire, with its shell, viewed from the side of the inflated valve. 2. The same seen from the side of the flat valve. 3. The Hyalea deprived of its shell, the lobes of the mantle drawn aside and expanded, from the in- flated side. 4. The same from the flat side, in which part of the viscera maybe obsers^ed through the membrane of the mantle, as also the muscular fibre of the latter. 5. The animal slightly magnified, -svith the mantle opened from the flat side, showing the retractor muscle and the viscera in situ. 6. The same, with the viscera displayed. 7. The same, seen from the opposite aspect : the integument of the neck has been divided as far as the mouth, showing the respective positions of the brain, of the oesophagus, of the penis, and the tongue; like terminations of the retractor muscle. 8. The penis detached. The crop and gizzard laid open. The same references apply to all the figures. a, b, c, prominent points of shell ; d, inflated valve ; e,f, lateral margins of the shell; g, h, i, k, margins of mantle : /, m, cervical fins ; n, mouth ; o, neck ; p, q, r, s, branchiae ; t, position of the heart ; u, re- tractor muscle ; v, v, oesophagus ; w, crop ; x, giz- zard ; y, intestine ; z, liver ; «, ovary ; /3, testicle ; y, supra-oesophageal ganglion. Other viscera occupy the arched and rounded portion of the shell, or the interior of the cervical region, and are enveloped in a kind of peritoneum of a blackish colour. On plac- ing the animal upon its flat valve, or ventral surface, the heart is seen to be situated on the right side, at the inner border of that portion of the branchial band marked t in fig. 1 14. 5. A cylindrical muscle (ii, fig. 114. 5 and 7) is attached to the intermediate point of the shell, and traverses the visceral mass to be inserted into the neck by four tongue-like processes. The action of this muscle will be to retract the creature within its shell. In front of the four branchiae is situated the penis, upon which lies the oesophagus, and this in turn is surmounted by the brain — these organs filling up the thickness of the neck. The oesophagus (v, v,fig. 1 14. 5 and 6) is long and slender, and the mouth, according to Cuvier, is a simple anterior opening, in the interior of which a few wrinkles only are perceptible, representing the tongue. The oesophagus dilates into a kind of membranous crop {iv, w,fig. 114. 7 and 9), which is suc- ceeded by a muscular gizzard (jc,x,fig. 114. 7 and 9) of a cylindrical shape, the walls of which are of tolerable thickness. Both these cavities are furnished internally with longitudinal folds, and these are thicker and more numerous in the crop than in the gizzard (fig. 114. 9). The intestine is slender, and of the same diameter throughout its whole length, which is considerable. It makes two convolutions in the interval between the lobes of the liver (z z,fig. 1 14. 7). The anus is situ- N 2 180 PTEROPODA. ated on the right side of the neck beneath the corresponding lateral fin : the liver is of no great bulk, and forms a nearly globular mass. The organs of generation consist of an ovary which occupies the greater portion of the right side ; of an oviduct of moderate length ; of a testicle which is almost as large as the ovary, and of a common deferent canal. The penis is here, as in Clio, an organ al- together distinct from the testicle : it is situ- ated, as already said, beneath the oesophagus, where it is folded upon itself ; and when pro- truded, issues through an orifice placed in the front of the neck and a little below the mouth. It is represented in situ in fg. 114.7, and detached in 8. The brain {fig. 114. 7, r) is large, flat, and of a square form, slightly narrowed pos- teriorly : the nerves issue principally from its angles, two of them going to join a double ganglion situated beneath the oesophagus. The salivary glands appear to be wanting. PxEuaiODERMA. — Auothcr genus of the Pteropod Mollusca, anatomized by Cuvier, embraces the Pneiimoderma, which presents many peculiarities of structure, more es- pecially as relates to the position of the re- spiratory organs and the tentacula placed at the sides of the mouth and other anatomical details, so that it will require to be described at length. In this genus, the body is without a shell, having two fins situated on the sides of the neck, but is distinguished by having two bunches of tentacula in the vicinity of the mouth, and by carrying its branchial organs at the surface of its body near its posterior ex- tremity. The body of this moUusk is of an oval shape (j'fg. i l5. 1, a), the head (6) is round, i^g. 115. (1 to 9). Anatomy of Pneiimoderma. {After Cuvier.') 1. Pneumoderma, natural size, anterior aspect. 2. The same, posterior aspect. 3. The same placed with the head doTVTiwards, and seen from the right side to show the branchiae. 4. The same enlarged and shoAvn in the position of fg. 1. The skin is di^'ided and tm-ued aside to show the muscular envelope of the viscera and the pericardium in situ. 5. The same, the muscular envelope and perito- neum laid open to show the ^'isce^a in situ. 6. The same, with the viscera developed. 7. The same : the organs of generation are turned aside ; the stomach laid open and the integuments of the head divided to show the mouth and its ap- purtenances. 8. The mass of the mouth detached and opened longitudinally to show its interior. 9. Interior of the head after the removal of the oral organs, showing the penis and the inferior ganglia in situ. The same letters answer to all the figures. a, body ; b, head ; c, mouth ; d, lips ; e, their fleshy appendage ; /, fins ; g, branchife ; h, branchial vein ; i, am-icle of heart ; k, pericardium ; / /, mus- cular envelope of viscera ; m, liver ; n, testicle ; o, ovarv ; p, stomach laid open ; q, rectmn ; r, r, fleshy appendages to oral ca-vity ; s, tongue ; t, u, anterior membranous compartment of mouth ; t, t, t, oral tubercles ; c, c, tentacles ; v, salivary glands ; x, their dilated ducts ; y, brain ; z, smaller mucous ganglia ; ct, penis ; /s, opening of common generative canal. PULSE. 181 and the neck constricted. The mouth opens upon the summit of the head, and is guarded in front by two longitudinal prominent h'ps {d, d\ beneath which is a pointed, fleshy ap- pendage (e). The fins (f,f), attached to the sides of the neck, are fleshy and much smaller than in either of the preceding genera. The branchiae (g,g) are situated at the op- posite extremity of the animal, and form two prominent lines somewhat in the shape of two capital Cs placed back to back and united by a transverse band. These lines give off from each side small prominent laminse, ar- ranged much in the same way as the leaflets of a pinnate leaf. On the right side of the body, and a little above the branchial apparatus, is seen a simple prominent line (k), which, on opening the animal, is discovered to be the branchial vein opening into the auricle of the heart (i), which, enclosed in its pericardium, is situated upon this side (i). On opening the integument, which is com- paratively soft, the mass of the viscera is found to be enclosed in a muscular envelope, the fibres of which are almost all longitudinal (^g. 1 15. 4, /, /). The pericardium is not con- tained within this fleshy envelope, which is only adherent to the skin in the vicinity of the branchiae ; for in this place are situated the arterial trunks, which convey the blood of the body into the pulmonary organ. On dividing the muscular layer (^g. l\5. 5 and 6), it is seen that almost the whole space within is nearly equally shared between the liver (?»), the testicle (n), and the ovary (o), the latter being slightly the largest viscus of the three. The ovary occupies the bottom of the visceral sac, the testicle is on the left, and the liver on the right side. The stomach is very capacious, and sur- rounded on all sides by the liver, which pours the bile directly into its interior through nu- merous orifices, exactly as in Conchiferous Mollusks. The walls of the stomach are thin and internally present numerous little cavities, into which the biliary pores open (fg. 1 15. 7, p). The rectum is short, and opens beneath the right fin (fg. 115. 7,^). The mouth is a fleshy mass of considerable size, from which two fleshy appendages are prolonged backwards ( fg. 1 15. 7, S,rr). The tongue is covered with short reverted spines, the use of which is evidently to assist in de- glutition (fg. 115. 8, s). The posterior part of the mouth, in which the tongue is situated, is separated from the anterior (^g. 1 15. 7, 8, u), which is membranous, by a fleshy construction (Jig. l\5. 8, ttt), upon which are perceived three small tubercles. The opening of the mouth is guarded by two bunches of tentacula (^g. 1 15. 1 to 8, c), which the animal can, at will, either protrude or retract within the oral orifice. Each of these tentacles consists of a delicate filament, terminated by a minute tubercle excavated in the centre. These organs forcibly remind us of the complicated oral apparatus of the Clio already described, and most probably are in- struments of prehension analogous to those of the Cephalopoda. The salivary glands (/g. 115. 7, 8, v r) are long and ample, and their excretory duct, as it passes above the brain, is obviously dilated (r.r). The brain (Jrg. 1 15. 9, is a narrow trans- verse band, and among the nerves which it furnishes, two may be observed on each side, which are connected beneath the oesophauus with a group of six ganglia, four of wh;ch are mesial and of considerable s'ze, while the other two placed at the sides are of smaller dimen- sions. There is nothing peculiar in the structure of the generative apparatus, which nearly resembles that of Hyalea and Clio. The penis is small, and situated beneath the mouth. It is protruded between the two little lips situated upon the anterior surface of the head (Jig. 115. 1, 5, d d). The common generative orifice is found immediately in front of the anus, and is prolonged externally into a kind of furrow, which is directed forwards. (T. Rymer .Tories.) THE PULSE (Gr. <7(pxr/uos, acpv^LS, Lat. Pulsus, Fr. Pou/s, Ger. Puis, Dut. Po/s, Ital. Polso, Span. Pu/so). — The nature and cause of the pulse have already been examined in an earlier part of this work.* It is proposed to consider it, in this place, as a separate and independent subject, and to bring together the leading facts which have been ascertained, in reference especially to that property which is most readily submitted to examination, namely, its frequency. Our knowledge of this subject is little more than a century old ; for though Quetelet f at- tributes to Kepler, who was born towards the end of the 16th century, the idea of ascer- taining the number of pulsations in a given time, Floyer, w ho wrote at the beginning of the l&th century, was the first who collected any considerable number of observations. Bryan Robinson j, Falconer 0, Knox [{, Graves'", Nick**, and Quetelet ff followed in the same field of inquiry, and still more recently the writer of this article. The facts which these authors placed on record have not yet been brought together in any standard treatise on physiology ; so that a clear and connected exposition of the frequency of the pulse, as it is affected by age, sex, posture, exercise, food, and other natural causes, and of the relation which it bears to the respiration, is still a desideratum. * Art. CiBcrLATiox, Vol. i. p. 638. t Sur rHomme, voL iL p. 80. t A treatise on the Animal Economv, by Brvan Ko'binson, M.D., 1732. § Observations respecting the Pulse, &c., bv TV. Falconer, M.D. F.E.S., Bath, 1796. jj Ed Med. and Surg. .Journal, voL xL, 1815, and Xo. 131, 1837. % Dublin Hospital Eeports, voL v. 1830. ** Beobachttmgen iiber die Bedingungen, unter denen die Haiirigkeit des Pulses im Gesunden Zus- tand verandert wird. Yon Georg. Heinrich Xick. tt Op.cit. N 3 I82 PULSE. It is true that there is no want of rough esti- mates, or of calculations founded on theoretical data ; but there is in this, as in most kindred subjects, a great lack of careful observations, and correct average results. This deficiency it is the object of this article to supply, by presenting in succession the number of the pulse, as influenced by the principal causes already specified. Age. — In treating this part of the subject no distinction is made between the sexes, nor is any notice taken of the influence of pos- ture, and time of day. The average results are based on the observations made by dif- ferent authors on healthy persons of both sexes iK a state of rest, and on those of the writer oi this article, which, with the excep- tion of \ei'y young children, were taken in the sitting posture in the middle of the day, and in a state of rest and abstinence. As these latter facts form the majority of those from which the averages are calculated, it will be correct to state that the tables pre- sent a near approximation to the frequency of the pulse in persons of different ages in a state of rest and abstinence, in the sitting posture, and at or about the middle of the day. The pulse has its maximum frequency in early infancy, and its minimum in robust old age. From infancy to adult age it continues to fall, and probably attains its lowest point at or about the age of 50, to rise again, if feeble as well as robust persons are included in our observations, in the aged. hifancy. — The frequency of the pulse is very variable at this period of hfe. According to Quetelet *, the numbers are as follow. Max. 165 ; min. 104 ; mean 135 ; range 61. Other authorities estimate it at 130 to 140, or at the last of these nS^ibers ; but it will assist the memory to fix the average at 140. During the first few weeks or months of life, the frequency of the pulse in healthy children is rapidly diminished, as appears from the following Table, based on the observations of Billard, in which table the averages must be understood to be approximations. Age. Max. Min. Mean. Range. 1 to 10 daysf 1 to 2 months 2 to 3 months 180 150 100 less than 80 70 70 106 103 87 100 80 30 * Op. cit. vol. ii. p. 86. t M. Yalleix (Memoires de la Societe Medicale de Paris, vol. ii. p. 312.) gives, as the average fre- quency of the pulse in thirteen healthy infants from 2 to 21 days old, 87 beats, the maximum being 104, and the minimum 76. As these observations were made with singular care, they are entitled to much attention. Mr. Gorham (London Med. Gaz. vol. xxi.) obtained from sixteen observations on sixteen infants, less than one day old, a mean of 123 beats, a maximum., of. 160, and a miuimimi of 100; and from forty.-'ttto'observations on infants, from one to seven days old — 128 as the average, 160 as the maximum, and 96 as the minimum. The average of three experiments on childi'en asleep was 108. M. Trousseau (Journal des Connaissances Medicales et Chirui-gicales, Juillet, 1841) obtained, as the Hence, then, between the first and tenth day there is a range of 100 beats ; between the first and second months, of 80 beats ; and between the second and third months, of 30 beats, with an average fall in the first three months of about 20 beats. The numbers of observations on which these averages are founded are, between 1 and 10 days, 56 ob- servations ; between 1 and 2 months, 36 ob- servations ; and between 2 and 3 months, 20 observations.* It would answer no good purpose to enter more minutely into the fre- quency of the pulse at these early periods of life ; it will suffice to present it year by year during the first twenty-five years of life, as is done in the following table, based upon be- tween 600 and 700 observations made chiefly by the writer of this article, each average being deduced either from 20 or 25 facts. Age. Max. Min. • Mean. Range. 1 158 108 128 50 2 136 84 107 52 3 124 84 106 40 4 124 80 105 44 5 133 80 101 53 6 124 70 95 54 . 7 128 72 90 56 8 112 72 92 40 9 114 65 87 49 10 120 76 91 44 11 100 56 84 44 12 120 70 94 50 13 112 70 84 42 14 114 68 86 46 15 112 60 84 52 16 104 66 83 38 17 102 54 76 48 18 104 58 74 46 19 108 60 76 48 20 106 52 72 54 21 99 59 74 40 22 96 41 68 55 23 100 60 74 40 24 84 52 71 32 25 88 59 73 29 average and extreme numbers of the pulse in six boys and five girls, aged from fifteen to thirty days, the following: — boys, max. 152, min. 96, average 127 ; girls, max. 152, min. 120, mean 135. * It is necessary to observe, that the obser\'ations of Billard, which give so low a frequency as 70 and 80 beats as of not infrequent occurrence before the third month, and even in the first ten days of life, are by no means borne out by the observations of the writer, or of any author wliom he has consulted, with the exception of M. Yalleix. Thus, the mini- mum during the first day is 104 ; nor does the pulse fall in any instance lower than that nimiber till the eighth week, when the least number is 90. If, again, the facts are grouped by months, the pulse is found in no case to fall below 104, except in one instance in the second month, till the eighth mouth, whea the minimum is 96. The minimum observed by M. Yalleix, occurred in a male infant, a year old, ad- mitted into the infirmary of the Hopital des Enfants Trouve's, in a state of languor, but free from disease. In a week from the date of admission the pulse had risen to 108 : on the folloAving day it was 117 ; and the day after that it Avas 113. There is reason to believe, therefore, that these low frequencies of the pulse of infants occur in that state and degree of de- bihty without disease which gives rise to" an infre- quent pulse in the adult, and'that they do not occur in strong and vigorous health. PULSE. 163 This table, though obviously based upon a number of facts too small to furni-^h exact averages, may be taken as presenting an ap- proximation to the truth. It indicates a progressive decline from infancy to aduit age as the true law of the pulse, — a law which would probably be clearly displayed by ave- rages deduced from a large number of facts. The following table presents the number of the Pulse at each quinquennial period through- out the whole of life. The averages for the first eight periods are founded each on 50 observations, of which half were made on males, and half on females. The average for the period from 76 to 80 is deduced from the same number of facts similarly divided. For most of the other periods the averages are derived from forty, observations, twenty on males, and twenty on females. Where the number of observations is less than this, it is stated in a note. Age. Max. Min. Mean. Range. 2 to 5 128 80 105 48 5 — 10 124 72 93 52 10 — 15 120 68 88 52 15 — 20 108 56 77 52 20 — 25 124 56 78 68 25 — 30 100 53 74 47 30 — 35 94 58 73 36 35 — 40 100 56 73 44 40 — 45 104 50 75 54 45 — 50 100 49 71 51 50 — 55* 88 55 74 33 55 — 60 108 48 74 60 60 — 65 100 54 72 46 65 — 70 96 52 75 44 70 — 75 104 54 74 50 75 — 80 94 50 72 44 80 and \ upwards! j 98 63 79 35 The want of regularity in this table arises from the same cause as in the former — the comparatively small number of facts. A regular and progressive decrease in the mean values, however, would probably not be ob- tained by any number of observations which it is in the power of a single individual to bring together, whether as the result of his own inquiries, or as derived from the recorded researches of others. But the figures of this table will still suffice to indicate a law of pro- gressive decrease from the beginning to the end of life, with an increase during the period of decrepitude. The decrease during the first four quinquennial periods is very rapid ; during the fourth and fifth the number re- mains nearly stationary ; from the fifth to the sixth period there is again a fall of a few beats ; but during the remainder of life (from 25 to 80) a very slight difference exists be- tween the several quinquennial periods ; the difference between the averages amounting to only 4 beats, between the minima to 10 beats, and between the maxima to 20 beats. The average rise during the period of decrepitude amounts to 7 beats. % * 22 Observations. t 29 Observations, t It would be interesting to accumulate observ- The pulse of the aged has been very care- fully examined by Leuret and Mitivie*, Hourmann and Deschambref, and Dr. C. W. Pennock.| According to the observations of the first-named authorities, the average fre- quency of the pulse in 27 males and .34 females, each sex being of the mean age of 71 years, was, in round numbers, 76. The number would have been somewhat higher but for the exclusion, as abnormal, of pulses exceeding 100. Dr. Pennock's observations on 170 males and 203 females, of the mean age of about 67 years, give as the average frequency of the pulse, 75 beats. The observations of Drs. Hourmann and Deschambre having been made solely on females, are not avail- able in this place. It will be seen that the results deduced from the observations of Leuret and Mitivie, and of Dr. Pennock do not differ materially from the numbers in the table. As it is extremely difficult, even for those who are most in the habit of dealing v/ith figures, to remember the exact results of a series of averages, it may be useful to lay down a near approximation to the average numbers at the several leading periods of life. This is done in the following table. At birth Infancy Childhood Youth - Adult age Old age Decrepitude 140 120 100 90 75 70 75—80. Sex. — The recorded observations on the pulses of males and females respectively during the early periods of life are few in number. At birth, according to the observations of Quetelet, there is a difference of only one beat, the average number in males being 136, and in females 135. The following table contrasts the two sexes at those periods at which the number of recorded observations, added to those made by the writer of this article, are ations on the pulse of the same person at dilFerent periods of life. The following memorandum, by the writer, of two series of observations on his own pulse, may be worth presers'ing. From an average of nine experiments made during my twentieth year, in the evening, between the hours of 9J and ll^, p.m., in the sitting posture, and, after remaining some time quiet (in one experiment some hoiu-s, and in two others during four hours each), the pulse was 72 per minute. From an average of the first nine experiments which present themselves, made under as nearly as possible the same circumstances, in my twenty-seventh year, the pulse is 55 per minute. Thus, in the space of seven years, it may be fairly inferred that the average frequency of my pulse has fallen from 72 beats per minute to 55, being a dWeF ence of 17 beats. ■ * De la Frequence des Pouls, chez les Alienes, par MM. Leuret et Mitivie, p. 35. f Archives Generales de Medicine (2nd series), Nov. 1835, tom. ix. p. 338. X Xote on the Frequency of the Pulse and Re- spiration of the Aged. By C. W. Pennock, M. D., American Journal of Medical Science, Julv 1847. N 4' 1S4 PULSE. sufficiently numerous to furnish a fair ave- rage.* Ma:es. Females. Under 2 vears 2 — o' — 5 _ 8 _ 8 — 12 — 110 101 85 79 lU 1 103 93 92 It would appear, then, that even at a very early period of life, the difference of the sexes is marked in the pulse f : that this difference is very inconsiderable in infancy, but well marked in chiidhooJ. The following table presents, in septennial periods, the results ot the observations of the writer during the whole of life. Each average is founded on 25 observations, made with great care, in apparently healthy per- sons, fasting, in a state of rest, in the middle of the day, and in a sitting posture. Age. Max. Min. 3Iearu Eange, 2 to 7 vears 128 70 97 56 8-^14 108 70 38 14—21 108 60 76 48 21—28 100 53 73 47 28—35 92 56 70 36 35—42 90 48 68 42 42—49 96 50 70 46 49—56 92 46 67 46 56—63 84 56 68 28 63—70 96 54 70 42 70—77 94 54 67 40 77-84J 97 50 ''l 47 2— 7 128 70 98 58 8—14 120 70 94 50 14—21 124 56 82 68 21—28 114 54 80 60 28—35 94 62 78 32 35-^ 1.00 56 78 44 42—49 106 64 77 42 49—56 96 64 76 32 56—63 108 60 4^ 63—70 100 52 4-S' 70—77 104 54 si 77-84§ 105 64 82 41 The same remarks apply to this table as to former tables. The number of facts is not laree enough to give a steady and progressive decrease from childhood to age: but that the approximation to a true result is sufficiently close for all practical purposes may be in- • The averages are deduced from the following nmnbers of facts.. Under 2 years, 28 and 21 facts ; 2 to 5 years 27 and 23 facts : 5 to 8 years, 32 and 33 facts ; 8 to 12 years, 46 and 59 facts. + This is in accordance with the observations of M. Talleix. (Op. cit.) J An average of 18 observations on males between 80 and 9(i by Dr. Pennock gives 724 beats, § Observations by Dr. Pennock on 37 females be- tween 80 and 9») give an average of 75 only ; and observations on 7 females between 9 " During the morning, the mere change of posture, from the horizontal to the erect, shall increase the pulse by about 15 or 20 beats. At mid- day this increase shall be 10 ; and in the evening 4, or 6." In his second essay, pub- lished in 1837, Dr. Knox gives the results of actual experiment. Nickf, in 1826, and Dr. Graves:}:, in 1830, also examined the subject experimentally. It is unnecessary to pursue the history of this department of the pulse into greater detail, as the fact that the pulse is greatly influenced by posture is now familiar to all medical men. The exact amount of the change due to this cause will, perhaps, be best displayed in the average results obtained by the writer from a large number of facts ob- served by himself. § The following averages were derived from observations on 100 healthy males of the mean age of 27 years, in a state of rest, unex- cited either by food or exercise, and, for the most part, between the hours of 12 and 2 p. M. : — Standing, T 8-90 ; sitting, 70-05; lying, 66'62. 1| Difference between standing and sitting, 8'85 ; between sitting and lying, 3-43 ; and between standing and lying, 12*28. These are the average results, from which, however, the extremes are very widely sepa- rated ; for the difference between standing and sitting ranges from 26 to 0 ; that between sitting and lying, from 18 to 0 ; and that be- tween standing and lying, from 44 to 0. The numbers in the observation, at the highest extreme of the scale, were as follows : — Age, 20. Standing, 98 ; sitting, 72 ; lying, 54 : differences, 26, 18, and 44. To the general rule that the pulse is more frequent standing than sitting, sitting than Advancement of Science, Dublin Meeting, 1835, p. 97. * Ed. Med. and Surg. Journal, vol. xi. and No. 131. t Op. cit. p. 41. X Op. cit. p. 561. I Guy's Hospital Reports, Nos. vi. and vii. II It is a remarkable coincidence that Dr. Harden, as the average of sc/eral experiments on his own person, obtained the same numbers, viz. 80, 70, and 66. See American Journal of Med. Science, vol. v. p. 342. lying, and, a fortiori, standing than lying, there are several exceptions. Thus there were 5 instances in which there was no difference between standing and sitting ; 19 in which there was no difference between sitting and lying ; and 2 in which the pulse had the same frequency standing and lying. Again, the pulse was more frequent sitting than standing in 3 instances ; lying than sitting in 11 instances ; lying than standing in 5 in- stances. The total number of instances, in which exceptions to the general rule occurred, was 34, or one-third of the whole. If we exclude all exceptions to the general rule, and deduce an average from the 66 ob- servations in which the pulse had what may be termed its normal character, we obtain the following numbers : — Mean age, 27; standing, 81-03; sitting, 71-12; lying, 65-62: differences, 9-91,5-50, and 15-41. The female pulse presents some pecu- liarities worthy of note, as will appear from the following average results of 50 observa- tions made under the same conditions as those just recorded : — Mean age, 27. Standing, 89-26 ; sitting, 81-98 ; lying, 80-24 : differences, 7-28, 1-74, and 9-02. The extreme results, in the female as in the male, are very wide of the averages ; for the difference between standing and sitting ranged from 24 to 0 ; between sitting and lying, from 11 to 0 ; and between standing and lying, from 28 to 0. The exceptions to the general rule are still more numerous in the female than in the male, the total number of exceptions being 60 per cent., and the number of observ- ations in which exceptions occurred 46 per cent. Of course the rule here referred to is the general rule established by observations on the male pulse. If, then, we compare the effect of change of posture on the male and female pulse, we discover that the effect is greater, and the exceptions to the rule less numerous, in the male than in the female. This part of the subject will repay a somewhat close examina- tion. In the following table, the numbers of the pulse, and the differences due to change of posture, are given, in round numbers, the averages being deduced from 66 observations in the male, and 27 in the female, from which all exceptions to the rule are excluded. The mean age in both sexes is 27. Standing. Sitting. L}ing. Differences. Males 81 71 66 10 5 15 Females 91 84 80 7 4 11 From this table it appears, that though the female pulse exceeds the male by 10 beats, or |th, the effect of a change of posture is con- siderably less in the former than in the latter. But, in order to determine the true relation PULSE. 187 existing between the pulses of the two sexes in this respect, it is necessary to compare equal things with equal. This is done in the following table, where the pulse in the erect posture, as deduced from 101 observations on males of the average age of 27 years, and 74 observations on females of the average age of 251 years, is in either sex 86. Standing. Sitting. Lying. Differences. Male I (77 72 9 5 14 Female j 86 {81 80 5 16 So that for the same frequency of pulse the effect of change of posture in the male is more than twice as great as in the female. The difference is still more strongly marked in early youth. The instances in which one or more ex- ceptions to general rules occurred are, as already stated, more numerous in the female than in the male, the exact proportions being 46 per cent, and 34 per cent. The next question connected with the effect of change of posture on the pulse is, whether that effect is the same at all ages '? The following table answers this question for both sexes in the negative. The averages are deduced from 30 observations at each age in the male, and 20 in the female. iding. .S &b p srences. ft MALE. Under 20, mean age 15 ") Above 20, mean age 29 j 83 (7Q {73 73 69 7 3 10 4 10 14 FEMALE. Under 20, mean age 11 \ Above 20, mean age 38 j 92 (88 {82 88 81 4 0 10 1 4 11 Hence, in the male, the difference above 20 between standing and lying is to the dif- ference below 20 as 7 to 5 ; while, in the female, the difference above 20 is to that below 20 as nearly 3 to 1. The exceptions to the general rule are also more frequent in the young subject. Another question connected with the effect of posture on the pulse requires to be exa- mined, namely, does that effect vary with the frequency of the pulse ? The following tables will be found to furnish an answer in the affirmative. The averages in the first table are founded each on 15, and in the second table on 10, observations. It will be seen that these tables concur in establishing the general rule, that the effect of change of posture increases with the frequency of the pulse; in the male as the numbers 9, 15, 27, 39 J in the female as the numbers 8, 12, 18. 50 to 70 70 to 90 bb a fcb ,c bb .5 bb .S bb c 1 '■C -i-> G -2 ■tj in i/2 j« 61 55 52 81 68 66 Differences. 6 3 9 13 2 15 90 to 110 110 to 130 bb a bb u bb c bb G bb 13 '-*-> xn m w. 101 82 74 120 93 81 Differences. 19 8 27 27 12 39 60 to 80 80 to 100 bb bb P! •-3 bb .S bb PI s J3 bb .c bb 5- a -3 m m CO m 71 67 63 92 85 80 Differences. 4 4 8 7 5 12 Differences. 100 to 120 bb bb S bb ,c Xfl 108 97 90 11 7 18 Another fact bearing on the effect of posture on the pulse, is established by the observa- tions of the writer, in confirmation of less accurate experiments previously made by Dr. Knox and others, viz. that that effect is not the same at all periods of the day. The only satisfactory way of ascertaining this fact is by contrasting the same frequency of the pulse at different periods of the day. This was done by the writer, who employed an average of twenty observations on his ow^n pulse, made before noon, twenty between 12 and 5^ p.m., and twenty between 5i p. m. and mJdnight. The greatest average difference between stand- ing and lying (10 beats) occurred before noon, the number in the afternoon being 8, and in the evening 9. The cause of the different frequency of the pulse in different postures of the body is a question of some interest, in examining which 188 PULSE. it is necessary to premise that the increase or diminution of frequency attending the change from one posture to another, is not merely a transient effect, dependent upon the muscular effort involved in the act of change, but a permanent state, continuing as long as the respective postures are maintained. This was long since stated by Dr. Graves *, who proved experimentally that when the posture of the body was changed without any effort of its own muscles, " the difference between the frequency in the horizontal and erect postures was not less than when muscular exertion was used." The mode in which Dr. Graves effected this change of posture is not stated ; but in experiments performed by the writer of the present article, by means of a revolving board -f , a difference amounting to less than a single beat was found to exist between the average of twenty experiments, in which the body was transferred from one posture to the other by the machine, and an average of twenty experiments, in which the change of posture was effected by the voluntary efforts of the same persons. The round numbers with the machine were, — standing 87, lying 74, difference 13; without the machine, — standing 89, lying 77, difference 12. This very slight difference is due to the effort of the muscles in effecting the change of posi- tion. When this is subtracted there still remains a much more considerable difference attributable to some permanent cause, which may be either the continuance of muscular effort, or some other condition. The differ- ence of opinion which has existed upon this subject, gives an interest to the following brief summary of the explanations advanced by the leading writers on the pulse. Bryan Robinson |, Falconer §, and Knox, without attempting to submit the question to the test of experiment, attribute, directly or by inference, tiie different frequency of the pulse, in different postures, to muscular contraction. Dr. Graves || , however, confesses himself to be altogether at a loss for an explanation ; Dr. Arnott 5[ seems to refer it to the more or less favourable position of the body, in respect to gravity, while other authors attribute it to the varying positions of the heart and its valves.** Very little consideration is required to show the futility of all the other causes, except that assumed by Robinson, Falconer, and Knox. The two postures between which there is the most marked difference in the frequency of the' pulse, viz. the erect and sitting postures, are precisely those in which there is no dif- ference in the position of the heart or its valves, and very little difference in the re- sistance offered to the circulation ; while the * Op. cit. p. 562. t Guy's Hospital Reports, No. VI. + Op. cit. p. 177. I Op. cit. p. 34. II Op. cit. p. 570. ^ Elements of Physics, vol. i. p. 570. See an Essay by Mr. Blackley, " On the Cause of the Pulse being affected by the Position of the Body," in the Dublin Journal of Medical and Che- mical Science, July, 1834. sitting and recumbent postures, between which there is so slight a difference in the number of the pulse, are accompanied by a marked change in the position of the heart and its valves, and of the column of blood to be propelled. On the other hand, the dif- ference in the amount of muscular contraction required to support the body in the erect and sitting postures, is much more considerable than that required to support the body in the sitting and recumbent positions — differences in strict conformity with the observed fre- quencies of the pulse in the several postures. This simple process of reasoning, therefore, serves to show the fallacy of the explanations now alluded to, and the reasonableness of the remaining alternative — muscular contrac- tion. With this strong probability the authorities just cited seem to have been satisfied; and as it did not occur to them to submit this very reasonable theory to the test of actual ex- periment, it was reserved for the writer of this article to place this mooted question beyond the reach of doubt. The experiments required for this purpose were of the very simplest kind. It was merely necessary in successive experiments to place the body in such circumstances as to exclude every other assigned cause but the contraction of the muscles ; in other words, the position of the body, and consequently of the organs of the circulation, remaining the same, first to support the body, and then to call its own muscles into action to maintain its position. The following are the results of a series of such experiments. 1. Difference between the pulse in the erect posture, without support, and leaning in the same posture, on an average of twelve experi- ments on the writer, 12 beats; and on an average of eight experiments on other healthy males, 8 beats. 2. Difference in the frequency of the pulse in the recumbent posture, tiilly supported, and partially supportetl, l-i beats, on an average of five experiments. 3. Sitting posture (mean of ten experiments on the writer), back supported, 80 ; unsup- ported, 87; difference, 7 beats. 4. Sitting posture with the legs raised at right angles to the body (average of twenty experiments on the writer), back unsup- ported, 86; supported, 68 ; difference, 18 beats. An average of fifteen experiments of the same kind on other healthy males gave the following numbers: — back unsupported, 80; supported, 68; being a difference of 12 beats. These experiments, with the simple reason- ings already advanced, serve to demonstrate the true cause of the varying frequency of the pulse in different postures of the body to be muscular contraction. The effect of an inverted position of the body on the frequency of the pulse has been made the subject of experiment by Dr. Graves, and subsequently by the writer of this essay. The reader is referred for an exact account of the experiments to the Guy's Hospital PULSE. 189 Reports, No. VIF. It will be sufficient to state, that in the inverted position of the body the pulse becomes less frequent, especially in persons accustomed to this unusual posture. In two such instances the difference between the erect and recumbent postures equalled that between the recumbent and the inverted postures, being in both cases 15 beats. The following is a short summary of the leadina: facts relating to the effect of posture on the pulse. 1. In the healthy adult male the mean numbers of the pulse are as follows: — Stand- ing, 79; sitting, 70; lying, 67; including all exceptions to the rule. Standing, 81; sitting, 71 ; lying, 66 ; excluding all exceptions to the rule. 2. In the healthy adult female the numbers are: — Standing, 89; sitting, 82; lying, 80; including all exceptions to the rule. Standing, 91 ; sitting, 84 ; lying, 80; excluding all ex- ceptions to the rule. 3. In both sexes the extremes are very remote from the mean results, and the ex- ceptions to general rules very numerous. 4. In both sexes, also, the effect of change of posture increases as the frequency of the pulse increases; but the exceptions to general rules are more numerous as the pulse is less frequent. 5. The effect of change of posture on any given frequency of the pulse is much greater in the male than in the female. 6. The effect of change of posture on the pulse is less in early youth than in the adult, and the modifying influence of age is greater in the female than in the male. 7. The exceptions to general rules are more numerous in early youth than at the adult a_'e. 8. The exceptions to general rules are more numerous as the effect of change of posture is less. 9. The effect of change of posture on the pulse is greater in the forenoon than in the afterpart of the day. 10. The inverted posture of the body les- sens the frequency of the pulse. 1 1. The varying frequency of the pulse in different postures of the body is due to mus- cular contraction. Exercise. — Muscular exertion increases the frequency of the pulse more than any other cause, as will sufficiently appear by the following quotation from Bryan Robinson.* " The pulse, in a minute, of a man lying, sitting, standing, or walking at the rate of two miles in an hour, at the rate of four miles in an hour, or running as fast as he could, were 64, 68, 78, 100, 140, and 150 or more." Change of posture, as has just been proved, forms merely a particular case of muscular effort. The act of changing from one posture to another, and the maintenance of different positions by the action of the muscles, both occasion an increased frequency of the pulse ; so also does the stretching out of the arm or the holding of it in the same posture, the * Op. cit. p. 177. pulse rising rapidly with the continuance of the effort, and falling, as the writer hai proved experimentally, on returning to a state of rest, below the frequency which it had before the effort was made ; and the same obser- vation applies to fatigue induced by long con- tinued exertion, as in walking. The cause of the increased frequency of the pulse which attends muscular effort is partly mechanical, that is to say, depending on the rapid pro- pulsion of the blood through the large veins, and partly due to the effort of the will which sets the muscles in action. It is probable, however, that the first-named cause is by far the most influential. Passive exercvie, as in riding and the various forms of carriage conveyance, has also a marked effect on the pulse ; an effect partly due to the varying action of the muscles in supporting the different postures into which the body is beins constantly throw n, and partly to a cause correctly pointed out by Dr. Ar- nott in the following passage. ** In a long vein below the heart, when the body falls, the blood, by its inertia and the supporting action of the vessels, does not fall so faat, and therefore really rises in the vein ; and as there are valves in the veins preventing return, the circulation is thus quickened w ith- out any muscular exhaustion on the part of the individual. This helps to explain the effect of the movement of carriages, of vessels at sea, of swings, &c., and the effect on the circulation of passive exercise generally, and leaves it less a mystery why these means are often so useful in certain states of weak health."* TniE OF Day — Diurnal Variations of THE Pulse. — This subject demands a more minute examination than it has yet received ; for it is extremely interesting in a physiolo- gical point of view. All the older and several comparatively modern authorities agree in representing the pulse as more frequent in the evening than in the morning. Hallert, Rye and Schwenke;;:, Gregorj O, Zimmerman [j , Hufeland , Quetelet **, ' Fodere tf , Falco- ner ji. Double, and Cullen, and, among mo. dern physiologists, Dr. Bostock ^0, describe an increase of frequency towards evening ; and more than one of these authors speak of a similar change occurring at noon and in the afternoon. Cullen especially insisted on this latter circumstance. It will facilitate our inquiry if we confine our attention for the present to the frequency of the pulse in the morning and in the even- ing, or in the earher and later periods of the day, reserving the alleged increase of frequency * Elements of Physics, voL L p. .52. t Opera Physiologica, Sectio 2, § xviL X Quoted by Haller, as above. I Conspectus Mediciiiie Theoretici?, cap. xv. ccccliii. j! On Experience in Physic, vol. L p. 250. ^ Makrobiotik, p. 53. ** Essai sur I'Homme Moyen, torn. ii. p 88. t+ Essai de Physiologie Positive, torn. L d. 190. Op. cit. p. 24. §§ Cyclopaedia of Practical Medicine, art. Pxilse. 190 PULSE. at noon and in the afternoon for subsequent consideration. The earlier authorities who have been cited as favourable to an increase of frequency towards evening were not without support from actual experiments, though those experi- ments were made in ignorance or disregard of some essential circumstances which tended to impair their value, such as the effect of pos- ture and of food and exercise. The earliest series of experiments which admits of being employed for the purpose of deciding this question is that contained in the Medicina Statica Britannica of Keill, published in 1718, and which the writer has been at some pains to analyse. Next in order of time are the tables of Bryan Robinson, published in his Animal Economy, 1732. The last series of facts, in confirmation of the opinion of the older authorities, was published by Falconer, in his Observations respecting the Pulse, pub- lished in 1796. It will economise time and space to present the general results of these three series of experiments in a tabular form.* Morning. Evening. Difference. Keill 80-50 89-72 9-22 Bryan Robinson (Pulses of A.) 70 76 6-00 (Pulses of B.) 68-50 78 9-50 Falconer - 69-60 76 6-40 Average 72-15 79-93 7-78 The results of these four series of experi- ments would appear to furnish a very strong probability in favour of the theory prevailing among the older authorities of an increased frequency of pulse towards the afterpart of the day ; and if all the experiments had been made in full cognisance of the influence of posture and other exciting causes on the pulse, and with a due regard to those circum- stances, they would have been quite conclu- sive. Even as it is, they must be admitted to establish a presumption, if not in favour of a universal law, at least for a general rule, or for a frequent exception to the opposite theory. Some experiments, however, per- formed by Nickf on his own person, of which part were made in the same manner as those of Robinson and Falconer, and part with the precautions just indicated, would lead us to entertain a doubt whether the older authorities may not have been altogether misled by an erroneous or careless mode of performing their experiments. Nick's expe- * A minute account of the experiments of Robin- son and Falconer, and of the literature of this part of the subject of the Pulse, will be found in the Me- dical Gazette, June 10. 1839. Keill's observations, from which the averages are calculated, amount to 256 in the morning, and 275 in the evening ; the observations of Bryan Robinson were continued for twelve weeks in the first case, and three weeks in the second ; while the observations of Falconer were continued almost daily for more than three months. t Op. cit. p. 5—13. riments, performed in the same manner as those of Keill, Robinson, and Falconer, that is to say, without any unusual precautions, gave, as an average of four series, made on four different days, a pulse of 59 at h past 7 A. M. and 64 at midnight ; and as the result of a single series beginning at 5 a. m. and ending at 10 p. M., a pulse of 59 for the first named hour, and 64 for the last. In each of these experi- ments the pulse was more frequent in the even- ing by 5 beats. In both these cases the posture was disregarded; but even when, as in Bryan Robinson's experiments, the sitting posture was preserved in all the observations, but other precautions disregarded, similar results were obtained. Thus, in one instance, the pulse was 66 at 6 a. m., and 71 at 8 p. m,; and in an average of three series of observations the pulse, which was 70 at 9 a. m., was 72 at ^ past 10 P.M. In the one case, therefore, there was an increase towards evening of 5, and in the other of 2 beats. When, however, the experiments were conducted still more carefully, the recumbent posture being pre- served in all the experiments, all mental and bodily excitement being avoided, no food taken, and the same temperature preserved, an average of six series of observations gave 63*8 as the pulse at 8 a. m., and 58 at 7 P. m., being a difference of 5'8 beats. The credit of propounding a diminished frequency of the pulse towards the afterpart of the day, as the true theory, is due to Dr. Knox*, who made several series of experi- ments, in order to establish it. The general results of these experiments with those of the writer, and some facts gleaned from other sources, are thrown together in a table.f As the true state of the case did not seem to be made out even by this balance of autho- rity, it was thought desirable to add to the number of observations. Accordingly several averages of the number of the pulse the first * Ed. Med and Surg. Journal, vol. xi. p. 53. 1815. f The second and third experiments of Dr. Knox were made after dinner and supper respectively. For full particulars of his other experiments the reader is referred either to the original essay or to the Medical Gazette, June, 1839. An account of the writer's experiments will be found in the Guy's Hospital Reports, No. viii. Dr. James Saunders' ex- periments were not made with any \aew to this ques- tion, but as a preliminary to the effect of digitalis on the pulse (Treatise on Pulmonary Consumption). Except when taking large doses of the drug, the pulse retained in this respect its normal character, being, in three experiments (dose 15 di-ops twace a day), 70 in the morning and 66 in the evening, and in two experiments (dose 25 di-ops), 76 in the morn- ing and 70 in the evening ; but when the dose was raised to 50 drops twice a day, the pulse became 80 in the morning and 90 in the evening, and, on the following day, when the dose was again reduced to 25 drops, it remained at the last named numbers. From some experiments on the pulse, which form part of Dr. Front's Essay on the quantity of car- bonic acid emitted from the lungs during respiration (Annals of Philosophy, vols. ii. and iv. 1813), it would appear that the morning and evening fre- quency was very nearly the same, the eleven ob- servations in the morning, which correspond with a like number in the evening, gi\ang as averages 70-91 and 70-27. PULSE. Dr. Knox Dr. Nick - Dr. Guy Dr. James S Dr. Harden* Nig'ht. Difference. 68-50 64-38 4-12 72-00 64-39 7-61 79-33 63-30 16-03 79-25 66-66 LZ Ov 94-60 65-78 28*82 63-80 58-00 5-80 6-50 64-00 54-00 10-00 60-00 56-00 4-00 64-00 62-00 2-00 thing in the morning and the last at night, founded on from two to ten observations at each period, in healthy young persons of both sexes, were obtained, with what result will be seen in the following tables. STATE OF THE PULSE, MORNING AND EVENING, IN aiALES. No. of the Pulse. Age. Morning. Evening. Difference. 21 67 80 13 in excess 21 71 80 9 20 65 75 10 19 81 71 10 in defect 27 63 61 2 15 92 85 7 18 82 73 9 22 761 75 U STATE OF THE PULSE, MORNING AND EVENING, IN FEJLALES. No. of the Pulse. Age. Morning. Evening. Difference. 22 108 120 12 in excess 51 87 80 7 in defect 26 91 81 10 14 99 81 18 26 92 84 8 24 100 84 16 23 82 82 0 22 101 101 0 The facts contained in these tables and in the previous table, together with the two series of experiments performed by Nick, may be taken to establish the general law first set forth by Dr. Knox, that the pulse is less fre- quent in the evening than in the morning; but it is obviously subject to numerous ex- ceptions. This law derives some confirmation from the fact that the only series of experiments on females which the writer has met with (those of Friedrich Hohl on pregnant women f) yielil averages in conformity with it ; for on comparing the mean of 25 observations made * American Journal of Medical Sciences, vol. v. p. 341. •j- Die Geburtshiilfliche Exploration, bey Anton Friedrich Hohl. on the pulses of pregnant women in the morfi!»^P ing with a mean of the same number made on the same women in the evening, the pulse in the morning was 83'28, and in the evening 80 88, being a difference of 2'40. The same author also states that the pulse of the new- born infant, and of the foetus in utero are more frequent in the morning than in the even- ing.* The interval between the morning and evening is filled up by pulses of very variable frequency, where the experiments are not made with due precaution ; but where, as in the second series of experiments by Nick, and in those of Knox, and of the present writer, the body remains in the same posture, in a state of rest, and unexcited by stimu- lating food, the fall in the frequency of the pulse is for the most part progressive, and free from those accelerations at noon and in the evening of which Double and Cullen have made mention. The diminished frequency of the pulse to- wards the afterpart of the day seems to de- pend altogether on the exhaustion of the strength, and is a less degree of that marked diminution of frequency which often accom- panies a convalescence from severe disease. That it is not dependent merely on the ab- sence of exertion ; in other words, that it is not the effect of continued rest, is proved by the facts now to be mentioned. It has been experimentally proved, both by Dr. Knox and by the writer of this article, that the pulse is not only less frequent in the evening than in the morning, but that it is also less excitable. So marked is the dif- ference in this respect, that in some experi- ments recorded in the Guy's Hospital Re- portsf, the very same food, which in the morning increased the frequency of the pulse from five to twelve beats, and kept it raised above its natural number from one to two hours, produced no effect whatever in the evening. This fact is in strict keeping with the well known effect of spirituous liquors in the early part of the day, as compared with their action on the system in the evening. The pulse in males appears to follow the same rule in disease as in health. The rule is inverted in females ; but in both sexes the exceptions are very numerous. J Rest. — From what has already been stated it will be inferred that the absence of exertion has the effect of diminishing the frequency of the pulse. Sleep. — The pulse falls during s'eep, slightly in adults, but considerably in young children. In six observations made by Nick on as many young adults, the mean decrease was some- what more than three beats. Quetelet, in a girl from three to four years of age, found a * An average of twenty-five observations on the morning pulse of the foetus in utero gave 138-08 beats, and on the evening pulse 135-76, a difference of 2-32 beats. Hohl himself recognizes this fact, and distinctly states that the pulse of the foetus is more frequent in the morning than in the evening. f Xo. \-iii. X Ed. Med. and Surg. Journal, No. 146. 192 PULSE. difference of 10 beats ; in a boy from four to five years old, 16 beats ; and in a female, in her 27th year, 10 beats. In two pregnant women Hohl observed a difference of 10 and 1 1 beats respectively ; and the same author reports a difference of from 20 to 40 beats in new-born infants. He also attributes a re- markable decrease of frequency sometimes observed in the foetal pulse to the sleep of the embryo. Other authors have been cognisant of the effect of sleep, but have not made it the subject of experiment. Food. — The general effect of food is to excite the pulse; this takes place to a very slight extent with vegetable food, but more with animal food. Some articles of diet, as warm drinks, alcoholic liquors, and tobacco have a very marked influence on the pulse. The effect of food is nmch more considerable in infancy than in after life. * Mental Emotions. — The effect of these on the pulse is too well known to require any comment. Temperature of the Body. — Cold lowers the pulse, heat quickens it. Exposure to a very high temperature causes a marked accelera- tion. Thus Sir C. Blagden, on exposing himself for 8 minutes to a temperature of about 260°, found his pulse rise to 144, or double its ordinary frequency, f Density of the Air. — In the observations hitherto made, it is very difficult to separate the influence of this agent from that of the exertion which accompanied the change from one medium to another. There was a very considerable increase of frequency in the case of the men who accompanied Saussure in the ascent of Mont Blanc. The pulses that beat at Chamounix 49, 66, and 72, became, on the summit of the mountain, 98, 112, and 100 re- spectively. Dr. Clark also found the pulses of his companions, in a state of rest on the summit of the mountain, 84, 84, 88, 92, 102, and 108 respectively, being a considerable increase above the probable frequency of the pulses of the same persons under ordinary circumstances. J Miiller^, on the authority of Parrot, gives a table of the frequencies of the pulse corresponding to different elevations. They are as follows : — Level of the sea, 70 ; 1000 metres, 75; 1500 metres, 82 ; 2000 me- tres, 90 ; 2500 metres, 95 ; 3000 metres, 100 ; 4000 metres, 1 10. These numbers are pro- bably unauthorised by experiments. The foregoing are some of the leading causes which affect the frequency of the pulse in health. They may be thrown into two classes ; those which increase, and those which diminish its frequency. 1. The more common causes of increased frequency of pulse are : — Exercise, active and passive ; continued muscular effort ; a change from a posture requiring little, to one re- quiring more exertion ; food, especially warm * Experiments of M. Valleix, Op. cit. p. 336. t See Sir David Brewster's Natiiral Magic, p. 311. X See Auldjo's Ascent of Mont Blanc, p. 68. § Physiology, vol. i. p. 163. drinks ; spirituous liquors and tobacco ; a high temperature ; diminished pressure of the air; extreme debihty ; sleeplessness ; the first degree of plethora ; and exciting passions and emotions. 2. The common causes of diminished fre- quency of the pulse are, — continued rest; sleep ; fatigue, when not carried to excess ; debility, when not extreme, and unaccompa- nied by disease ; cold ; increased atmospheric pressure ; a change from the erect to the sitting, and from the sitting to the recumbent posture, and the inverted position of the body ; and depressing passions of the mind. Hitherto we have been speaking solely of that character of the pulse which is most easily examined, — its frequency. To render the subject complete, it will be necessary to speak briefly of certain other characteristics of the healthy pulse. The pulse of the healthy adult male may be described as regular, equal, moderately full, compressible, and swelling slowly under the finger ; that of the female, and of the child of both sexes, is smaller, and quicker in the beat. The pulse of persons of the sanguine temperament is full, hard, and quick ; that of persons of the lymphatic temperament is softer, and slower in the beat. In old age the pulse, in consequence of the increased firmness of the arteries, assumes a hardness which would not otherwise belong to it. Exceptions to the general rule are not of very rare occurrence in persons who enjoy good health. — There are some persons, for instance, in whom every slight attack of indigestion, especially when attended with flatulence, leads to a well marked intermission. Instances are also on record in which the pulse is uniformly irregular or even distinctly intermittent in health, becoming regular in disease, and resuming its irregularity on re- covery. One other subject connected with the phy- siology of the pulse still remains to be exa- mined, viz. The relation of the Pulse to the Respiration. — The proportion which the pulse bears to the respiration has been va- riously stated by authors. Quetelet*, Parry f, Burdach, and the greater number of physio- logists estimate it as 4 to 1 ; ioyX as 4^ to I ; and Floyer as 5 to \.§ M. Valleix states it at 4 to 1 in infants. Little dependence, however, is to be placed upon any of these estimates, as they were made in ignorance of the very remarkable effect of posture on the respiration ; and as the respiration itself was probably counted for very short intervals of time, and under the disturbing influence of a consciousness of the observation which was being made. Though the posture of the body, in which the pulse and respiration were counted, is not distinctly stated by the authors who have put forward the foregoing estimates, * Op. cit. vol. ii. p. 86. t Pathology, vol. i. § 890. t Library of Practical Medicine, vol. iii. p. 274. § Pulse Watch, p. 331. PULSE. 193 it is most probable that it was the recumbent posture; for it is in that posture that the breathing is most easily counted ; and as it is possible, when the subject of the observation is lying down, to place the hand on the abdo- men, still retaining the hold upon the wrist, and to count the breathing while he remains unconscious of the object of the observer, the true number of the respirations, as compared with that of the pulse, may be ascertained with tolerable accuracy. Eighteen such ob- servations, made by the writer on as many healthy young men, gave as the average pro- portion 3-72 to 1, and thirteen observations on as many more healthy and adult females, the proportion of 3-61 to 1. The extremes, in the observations on males, were 2*54 to 1, and 5'33 to 1 ; and in females, 3*10 to ], and 4'33 to 1. In these observations the re- spiration was counted, immediately after the pulse, for two consecutive minutes. Bryan Robinson, as the result of three observations on the same number of healthy males in the sitting posture, obtained numbers of the pulse and respiration, from which the calcu- lated proportions are 3*82 to 1, 3-79 to 1, and 3-86 to 1. Quetelet*, from a series of 300 experiments on males of different ages, ob- tained the following proportions : — At birth, 3-09 to 1. 5 years of age, 3*38 to 1. 15 to 20 - - 3-72 to 1. 25 to 30 - - 4-43 to 1. 30 to 50 - - 3-88 to 1. In his own case, the average proportion was 4" 19 to 1. From a smaller number of observations on females, the following pro- portions were obtained : — At birth, 3*09 to 1. 15 to 20 years of age, 4*10 to 1. 20 to 25 - - 4-52 to 1. 30 to 50 - - 3-92 to 1. From other observations by the same author, it would appear that the proportion of the pulse to the respiration during sleep is lower than in the same persons awake, in consequence of the respiration being more affected during sleep than the pulse. Thus, in a girl from 3 to 4 years of age, the mean proportion of the pulse to the respiration was 3*40 to 1 awake, and 3*68 to 1 asleep ; in a boy from 4 to 5 years old, 3-21 to 1 awake, and 3*50 to 1 asleep ; and in a female in her 27th year, 2*85 to 1 awake, and 3*19 to 1 asleep. The averages are deduced from " iin assez grand nombre d' observations" and were probably made in the recumbent posture. Drs. Hourmann and Deschambre obtained, as the result of 255 observations on aged females, 3*41 to 1, or, excluding extreme fre- quencies both in excess and defect, 3'65 to 1. Dr. Pennock, from 146 observations on aged males, obtained a mean of 3-51 to 1, and from 143 observations on aged females, 3-53 to 1. As the respiration is greatly under the control of the will, to obtain the requisite ac- curacy in observations of this nature it would be necessary to adopt some measures by which it might be counted for several minutes at least in succession, the subject of the ob- servation being either unconscious of what is going on, or having his attention diverted from it. This object the writer has accom- plished by converting the common pocket pedometer into an instrument for registering the respirations ; and by means of it, has made several hundreds of observations during pe- riods of half an hour each, the pulse being counted for one or two minutes before and after each registration of the respirations, and the average of the two or four minutes being taken to represent the frequency of the pulse during the whole period of the experiment. The greater number of the experiments were made in the sitting posture, with the back supported, the attention being diverted from the breathing by engaging in study.* The, following are the principal results obtained in this manner: — the average proportion from 238 experiments performed in the manner just described, the pulse varying from 44 to 85 beats, and the respiration from 15^^ to 20^^, was 3'47 to 1. The extreme proportions were 2*6 1 to 1, and 5 to 1. The average proportions varied with the number of the pulse, as shown in the following table : — • No. of Observations. False. Proportion. 8 45—50 2-75 to 1 87 50—55 3-05 to 1 50 55—60 3-31 to 1 50 60—65 3-52 to 1 50 65—70 3-59 to 1 27 70—75 3-82 to 1 12 75—80 4-18 to 1 4 80—85 4-31 to 1 * Vol. ii. p. 86. From the results of these experiments, then, it would appear that the proportion which the pulse bears to the respiration, in the same posture of the body, diminishes as the frequency of the pulse increases. Another fact established by these experi- ments is the different frequency of the respira- tion morning and evening for the same fre- quency of pulse. Thus, for a pulse of 63, being an average of 50 experiments in the morning and 50 in the evening, the number of respirations in the morning was 17*60, and in the evening 18'58, being as nearly as pos- sible as the numbers 17 and 18. The effect of posture on the respiration, and the proportion which it bears to the pulse, is, however, still more remarkable than that of the time of the day. Thus, to take the only instance in which it was possible to compare the proportion of the pulse to the * An abstract of the results of these experiments was first pviblished in the first part of Hooper's Phy- sician's Vade Mecum, edited by the writer early in the year 1842. VOL. IV. 194 QUADRUMANA. respiration in three postures of the body for the same number of the pulse : the pulse being G4, the proportions were : — standing, 2'95 to 1. sitting, 3'35 to ]. lying, 4-97 to 1. Again, an average of 14 experiments, in which the pulse in the sitting and recumbent posture had the same frequency, namely, 62*40, gave the following results : sitting, 3*30 to 1. lying, 4-39 to 1. The difference between the erect and sitting posture is less considerable, as will appear from the following average results of six observations, in which the pulse had the same frequency in these two postures, namely, 61-45; standing, 3*05 to 1. sitting, 3*40 to I. The proportion which the pulse bears to the respiration, therefore, is greater in the erect than in the sitting posture, and in the sitting than in the recumbent posture ; but the difference is greater in the latter than in the former case. If experiments made with great care upon a single individual in the enjoyment of good health may be employed to establish general rules, the following may be laid down in refer- ence to the proportion between the pulse and respiration. 1. The proportion which the pulse bears to the respiration varies greatly with the fre- quency of the pulse. 2. The proportion of the puLse to the respiration decreases as the frequency of the pulse increases. 3. The proportion of the pulse to the respiration for the same frequency of the pulse is greater in the evening than in the morning ; the respirations in the evening being to those in the morning as 18 to 17. 4. The proportion of the pulse to the respiration varies in different postures, being higher in the erect than in the sitting, and in the sitting than in the recumbent posture ; the difference between the sitting and the recum- bent posture being greater than between the sitting and erect posture. Since these results were published. Dr. Harden, of Georgia, U. S , has published an account of some experiments on the pulse and respiration * made on his own person, but without the use of any registering instru- ment. They are, to a certain extent, con- firmatory of the results obtained by the writer. The average number of respirations was as follows: — Standing, 16; sitting, 14; lying, 12; the average numbers of the pulse in the same postures, 80, 70, and 66. By selecting from the table published by Dr. Harden five * Observations on the Pulse and Respiration, by John M. B. Harden, M.D., of Liberty County, Georgia. American J ournal of the Medical Sciences, April 1843, vol. v. p. 340. observations, in which the pulse, in each of the three postures, was 68, the following num- bers are obtained: — Respirations, standing, 15*2 ; sitting, 14*4 ; lying, 13. The propor- tions consequently are 4'47 to 1, 4*72 to 1, and 5*23 to 1, which follow the same order as the experiments of the writer, though they present smaller differences. The respira- tions are also more numerous in the evening than in the morning, in the proportion of 13i and 13, the ^ulse being 62 at the former period, and 64 at the latter. Calculations founded on the observations of Dr. Pennock, already more than once re- ferred to, confirm the preceding results, as far as the standing and sitting postures are concerned. As the calculations in question serve to exhibit the relation existing between the Pulse and Respiration in advanced age, as well as, by inference, the increasing frequency of the respiration in the aged, they are ap- pended in a tabular form. Males. Age. Sitting. Standing. 50—60 3-71 to 1 3-68 to 1 60—70 3-39 to 1 3-26 to 1 70—80 3-29 to .1 3-23 to 1 80—90 3-07 to 1 2-96 to 1 Feinales. 50—60 3-65 to 1 3-61 to 1 60—70 3-62 to 1 3-62 to 1 70—80 3-69 to 1 3-49 to 1 80—90 3-46 to 1 3-29 to 1 90—115 2-94 to 1 2-06 to 1 These results are somewhat at variance with those obtained by Hourmann and Des- chambre, who found both the pulse and re- spiration to increase in frequency with the advance of age, but in consequence of the former increasing more rapidly than the latter, the proportion between the one and the other diminished instead of increasing. The effect of posture on the pulse and respiration was not examined by them ; and it is probable that their observations were made in the re- cumbent position. Such are the leading results of careful observation on the frequency of the pulse as affected by the more influential natural causes. Bibliography. The leading monographs and essays which contain well observed facts bearing on the physiology of the pulse, Avill be found among the references in the foot-notes. The older works a,re so filled with fanciful conceits, and are so little likely to be referred to, that it has not been thought necessary to give a list of them in this place. {William A. Gut/.) QUADRUMANA. — The four-handed order of Mammalia, deriving their name from the thumb being opposed to the other fingers and toes, in the feet as well as in the hands, by which peculiarity they are enal)led to grasp objects both with their anterior and with their posterior extremities. According QUADRUMANA. 195 to zoological and zootomical observations, they ought to be divided into two great fami- lies, the Simics and the Lemurince. I. SiMi^. Monkei/s. Singes^ French. Af- fen. Germ. ApeUy Dutch. This name includes the Quadrumana with four vertical incisor teeth in each jaw, and in general flat and similar nails at the tops of the lingers and toes, two characters by which they approach to man ; the molar teeth have smooth tubercles, and consequently they feed in general upon fruit ; but the canine teeth are stronger than in man, and have their summits not in the same level as the other teeth, but more prominent. There is consequently, in the same manner as in the Carnivora, an interval in the upper jaw, between the exterior incisor and the canine tooth, in which the canine of the opposed jaw is received. They consist of two distinct groups, of which the first is con- fined to the old world, and is familiarly known under the name of Apes, Monkeys, and Ba- boons, These, the anatomical structure of which will be described in the first instance, have the same number of teeth as man, and approach to him in many respects, but differ so much from each other, that it is necessary to divide them into various genera. 1. SiMi^ VERiE, Monkeys of the Old Con- tinent, Simice catarrliince Geoffr. In general the same number of teeth as in man, viz. 4< , 1 1 5 5 incisors - ; canines ; molars . Nos- 4 1 — 1 5 — 5 trils situated under the nose. a. First Genus. Simia, Ape. In general the same number of teeth as in man, but stronger, especially the canine ; an interval between the exterior incisor and the canine in the upper jaw. No callosities on the buttocks ; no tail ; the fore-feet or arms much longer than the hinder. The hair of the head is directed forwards, so as to shade the temples, and that of the fore-arm reverted upwards, in the direction of the elbow, where, encountering the hair of the humerus, which grows in the opposite direction, it stands out in the form of a prominent ruff. They want the cheek-pouches, but possess very large membranaceous expansions communicating with the larynx. In the form of the hyoid bone, in the structure of the brain, and many other parts of their organisation, they ap- proach the nearest to man. They inhabit tropical Asia and equinoctial Africa. Spec. — Simia troglodytes ^ Chimpanzee ; Shnia Satyrus, Orang-oetan. b. Second Genus. Hylobates Illiger. Gibbon, French. Armaffe^ Germ. Langarmige Aap, Dutch. The same excessive length of the arms, i which are so long as to touch the ground, i when the animal is in a semi-erect attitude. Callosities on the buttocks, as in the Cerco- \ pitheci, from which the Gibbons differ by the want of a tail, and of cheek-pouches. The form and number of teeth arc the same as in Simia and in man, but the crowns of the true molars have a more rounded contour than in the inferior quadrumana, and in their relative size they resemble more the molars of the Carnivora than do those of the genus Simia. The Gibbons are restricted to the forests of tropical India, and their activity in climbing is surprising. They want the laryngeal pouch. Spec. — Hylobates lar, H. varicgatus, H. leuciscuSy the Siamaiig {H. syndacty- lus) ought to be separated from the other Gibbons. It has the second and third toe* united by a narrow membrane, extended over the whole length of the first phalanx, and possesses a laryngeal pouch. Its skeleton approaches most to that of man. Its hair is directed as in the Orangs. c. Third Genus. Seinnopithecus F. Cuv. Slank-aap, Dutch. Long, but slender and straight tail.f They have no cheek-pouches, but they possess a membranaceous, and small laryngeal, expan- sion. Callosities on the buttocks. Ex- tremities, principally the hinder, very long, as also the fingers and toes, with the exception of the thumb of the hinder hand or foot, which is short, and removed from the outer toes. The slenderness of their body, and largely-developed extremities, enable the Sem^ nopithcci to display a great deal of activity. Their stomach is very large, and divided into three or four pouches. The teeth differ from those of the Gibbons by the existence of a posterior tubercle on the last molar teeth of the lower jaw. They inhabit the Indian Con- tinent and the Indian islands, principally Bor- neo, and are there the constant companions of tlie Gibbons, with which they have a great analogy. Spec. — Semnopitheciis entellus, S. lenco' prymnus (including Simia latibarbata, Ct?- plialoptera, and S. Nestor, Benn.), ^S*. leucomystax, S. mitratus, S. melalophos, S. ru^ bicunduSy S. chrysomelas^ S. maurus, S. fron^ tatuSy S. nemceus, S. nasicus. To these could be added, 1. S. cucullatns, but it seems but a local variety of S. leucoprymniis ; 2. S. Sia- Diensis, which is a local variety of S. mitratus ; 3. S. Jlavimamis, which is a local variety of S. melalophos ; 4. S. Sumatranns^ local variety of .S". chrysomelas ; 5. S. cristaftis, variety of S. maurus. S. Muller and H. Schlegel presume that S. albogularis Sykes is a va- riety of S. entellus; but according to the observations of Ogilby, this monkey is a Cercopithecus. In the enumeration of the * According to the observations of Ogilby and F. CuviER, this character is not exckisive in the Siamang, but obvious also in many other species of Gibbons. f S. Muller and H. Schlegel have proved in their monograph on the genus Semnopithecus, that it is by a mistake that most of the authors on natural history describe and figure the tail of Semno-pitheci as incurvated in the same manner as in squirrels. It hangs straight below when they climb, and is merely horizontal and touching the ground when they walk. 196 QUADRUMANA. other species, I followed the direction given by the said authors. d. Fourth Genus, Colohus Illiger. This genus represents in North Africa the Semnopitheci of South Asia, and seems only to differ from them by the rudimentary con- dition of the thumb, and, in one species, C. verus Van Beneden *, by the total want of it. By this disposition the Se77mopitheci and Colobi may be compared with the genus Ateles from the New World, in which some species want the thumb, and others possess it : they seem, in fact, to represent that genus in the Old World, having a great deal of conformity with it in structure, manners, and character. RuppELL-f- has proved, by dissection of the Colohus guereza, that in this genus the stomach approaches to that of the Semnopitheci, by its extension and the exist- ence of separate cells. The teeth are the same as in the Semnopitheci, viz., with an additional tubercle to the posterior molar of the lower jaw. The first molar of the lower jaw on each side is inclined backwards, and gives also room for the canine of the upper jaw. In both the Semnopitheci and Co/ohi, detrition of the molar teeth seems to take place in a longitudinal direction, as has been shown by Ogilby, indicating a corresponding motion of the jaws, something similar to what takes place in the Rodentia. They have cheek- pouches and ischial callosities. Spec. — Colobus polycomos^ C. ferrughieus^ C. guerezuy C. verus. e. Fifth Genus. Cercopithecus, Monkey, Engl. Guenon, Fr. Prominent jaws ; cheek-pouches ; naked callosities on the buttocks, and long but not slender tail ; arms much shorter than the pos- terior limbs, by which disposition the Cerco- pithed climb with much agility, but walk with more difficulty : consequently they are syl- van in their habits, and confined in general to the woods of Africa. They possess in general a laryngeal pouch, and their posterior molar of the lower jaw wants in general the ad- ditional tubercle proper to the Semnopitheci. The first molar of the lower jaw is disposed as in Colobus. They are quick, capricious, choleric, cunning, and very teachable. They are a pre-eminently sylvan race, and live in the forests in society, under the guidance of the old males. Each tribe or family has its own particular district, into which individuals of other tribes or species are not allowed to intrude. So strongly is this propensity im- planted in the Cei-copitheci, that they carry it with them even into our menageries. They feed indiscriminately upon wild fruits, the seeds and buds of trees, insects, birds' eggs, &c., but appear on the whole to be less car^ * P. S. V^VN Benedex, Notice sur une Xouvelle Espfece de Singe d'Afrique, torn. v. n. 6. Bull, de I'Acad. Royale de Bruxelles. •j- E. RupPELL, Neue Wirbelthiere zu der Fauna von Abyssinien. Erankf. a. M. 1835—1840. nivorous in their appetites than either the Apes or Cynocephali. Spec. — Cercopithecus ruber, C. ^thiops, C. J'uliginosus, C. Sabceus, C. griseo-viridis, C. melarhinus, C. f annus, C. pygerylhrus. To this genus are also referred the C. mono, C. cephus, C. petauristus, C. nictitans, and C. Diana, which, according to the observa- tions of F. Cuvier, form a separate group, distinguished by their elegance of form and gentleness of manners and character. All these and the preceding Cercojntheci inhabit chiefly Africa. I intend also to introduce, upon the authority of Ogilby and Schlegel, in this genus three Asiatic and chiefly Indian species, which are referred by others to the genus Macacus, viz., C. cynomolgus, C. radi- atus, and C. jjileatus, Ogilby. Thev have an additional tubercle on the posterior molar of the lower jaw, and differ by it from the other species of the genus Cercopithecus ; but in their general form, external aspect, and man- ners, they offer the greatest analogy with the Cercopitheci, constituting a natural group with them, and forming, at the same time, a transition to the genus Inuus. I am fully convinced, that in forming a natural system, it is very wrong to be led by a single ana- tomical character. This additional tubercle of the molars is unquestionably a subordi- nate character, insufficient of itself to in- duce us to separate animals belonging to the same natural group. Geoffi'oy St. Hilaire seems to have had the same views, by the formation of his genus Cercocebusy in which he places the above-named three species, and Ogilby says that he found in the 2Ian- gabey and in the Collared Mangabey, which every one refers to the genus Cercopithecus, the tubercle in question ; a proof that it is not an essential character. Recently I. Geoffroy St. Hilaire has separated the C. melarhinus or Talapoin from the other Cer- copitheci, and has formed of it a new genus Miopithccus. The principal character is the existence of only three tubercles on the pos- terior molar of the lower jaw. But 1 am of opinion, that this is not sufficient for the formation of a separate genus. If such merely anatomical characters are admitted for the classification of animals, there will be within a short time as many genera as there are ani- mals. f. Sixth Genus^ Inuus Schlegel. Macacus Cnv. Macaque^Vr. Laponder-aap^Dutch. Upon the authority of my distinguished friend Schlegel*, curator of the splendid museum at Leyden, I am induced to unite the genus Ma- cacus Cuv. with the genus Inuus Schlegel. They form together a natural group, in which the tail becomes gradually shorter, and finally disappears, in the Inuus sylvanus or ecaudatus. An elongated muzzle, much more prominent than in the Cercopitheci^ with nostrils opening * Ogilby seems to agree wntli these \news, by the formation of his genus Papio, which is much similar to my genus Inutis. QUADRUMANA. 197 obliquely in its upper part, and a protruded superciliary ridge, give a peculiarly cunning, mistrustful, and somewhat ferocious physiog- nomy to these Inui, especially to the old ones. Their limbs are strong and compact ; by them, and by the shortness or the want of a tail, they are more a terrestrial than an arborial genus. They devour frogs, lizards, and large insects, as readily as vegetable sub- stances. They possess naked callosities, cheek-poaches, and laryngeal expansions. Their canines are very strong, and the pos- terior molars of the lower jaw have an ad- ditional tubercle. By the great development of the superior canine, the first molars of the lower jaw are inclined backwards on each side, and thus make room for the reception of those teeth. This character appears first in Colobus and Cercopithecu4, but it is not so distinct in these as in Inuns. Among the Cercopitheci it is the most apparent in C. cyno- molgxu, by which, and by the existence of the additional tubercle on the posterior mo- lars of the lower jaw, this forms, with its two congeners C. radiatus and C. sxnicujs or pde- atus, a transition to Inuus. This inclined direction of the first molar of the lower jaw becomes more distinct by age. It is rendered necessary, by the length of the superior canine tooth, and by the uninterrupted series of the canine and first molar in the lower jaw. By the action of the superior canine, there is pro- duced a surface for trituration, in the external surface of the anterior root of the first molar. The Inui inhabit generally eastern India. They are very gentle, industrious, and intel- ligent in their youth, but become ferocious and untameable in their old age. Spec. — InutLS rhesus^ I. speciosiLS^ I. nC' mestrinus, I. maurus^ I. st/Icanus or ecaudatus. Amongst these the /. syltanus is not only reraarkable by the want of a tail, but also by being the only one of this genus which comes within the geographic range of Europe ; great numbers, origiuaily fi*om Barbary, still inhabit- ing the inaccessible precipices of the rock of Gibraltar. g. Seventh Genus. Cynocephalus Cut. Ba- boon, Engl. Papion, Fr. Bariaan, Dutch. The same teeth as Inuus, but the canini of the upper jaw are enormously developed, and consequently the first molars of the lower jaw- are still more inclined. The cheek-pouches, the callosities, and the laryn£eal expansions, as in the precedent genera. Tne tail is either short, thick, and ending in a tuft of hair, or altogether deficient. A large, dog-shaped head, with a prominent, truncated, or, as it were, abruptly cut-off muzzle, with the nos- trils op>ening at the end, gives a hideous aspect to the CyyiocephaUy corresponding to their ferocious, disgusting, and formidable manners. To the prolongation of the face, and prepon- derance of the anterior over the posterior part of the head, is to be attributed, at least in a great measure, the fact that the CynocephaR less fi-equently assume the erect posture than any of the other Quadruraana, and even when they do, are less capable of maintaining it for any length of time. They are essentially con- structed for terrestrial progression. Their whole habits, as well as their organic struc- ture, approximate these animals to the ordinarj'^ quadrupeds. The great development of their organs of smell ; the position of the nostrils ; the robust make of their extremities, and their equality in point of length ; the size and power of their canine teeth, and the nature of their food ; all indicate their inferiority to the Apes and Monkeys. Their natural food consists of wild berries and bulbous roots, bird's eggs, insects, 6cc. In search of food, they go in large companies upon marauding parties, re- ciprocally to support each other, and to carry off their plunder in greater security. They inhabit principally Africa and the Philippine islands. Spec. — CynocephaliLS sUenus^ C. Spkynx, C. porcarius, C. hamadryas^ C. gelada^ C. ni- ger, C. leucophiBiLSy C. mormon. * I refer the C. silenus or Ouanderou to the Cynocephali^ by the prevailing authority of Dr. ScHLEGEL. The general physiognomy of this monkey, and the brush at the extremity of the taU, are sufficient characters to justify this determinarion. The C. sUenus forms with the C. niger the link of a chain uniting our genus Inuus with Cynocephalus. In both, the nostrils are not terminal, nor is the muzzle truncated, but disposed as in the Inui, while by the other characters they are Cynocephali, The Gelada. which was first brought to pubUc notice by the celebrated Dr. Kuppell, is certainly a Cynocephalus nearly alUed to C, hamadryas. In a skull of this monkey in the museum at Leyden, I was struck with the great conformity it has with the skull of the larger CynocephaR, for example, with the skuil of C. porcarius. It has the same pro- minent suf>erciliary ridges, the same deep orbits, the same prominent maxillary bones, and, above all, the same deep fossa on the facial surface of the supra- and infra-maxiliary bones. The Drill {C, lencoph^us ) and Man- drill ( C. mormon) ought to be separated from the rest by a t}-pi(^ pre-eminence. Their cheeks are promment, deeply ridged, and m the Mandrill beautifully coloured. Osteology. — If we consider the bonv framework of all the monkeys of the Old World, we find in it no less numerous dif- ferences than in their external form and habits. We may trace in it some successive stages, by which they deviate from the structure of man. and approximate to the skeleton of the larger Camicora. As I have stated elsewhere, they form an iminterrupted series, in the descending scale, beginning with the Chim- panzee, and ending with the Cynocephali. The skull of the Chimpanzee {Jig. 116) is of a narrow, elongated tbrin, slighUy contracted * Recently L Geofeoy St. HiUire has separated the C. pelada under the name of TVeqpAfterms, and the C. Htffer under the name of OfnapiAeaa niper. But I am afraid that the introduction of all tbese new genera does not conmtoxe an haprcfTODeat tat science. o 3 198 QUADRUMANA. towards the anterior part, which is, as it were, truncated. The cerebral portion, or the cra- Flg. 116. Skull of Simla troglodytes. (^After Owen.') nium, is smooth, and convex on its superior or coronal aspect, being devoid of the inter- muscular frontal and sagittal crests, which give so strong a carnivorous character to the skull of the Orang-cetnn, For the insertion of the temporal muscle there is, however, a long boundary continued from the outer part of the supra-orbital ridge, at first as a well- marked crest, but soon becoming a slightly elevated Hue, which is lost in the lambdoidal and supra-auditory ridges. The coronal su- ture has a transverse direction ; the occipital foramen is further from the posterior plane of the cranium, and its position is less oblique than in the Orang-cetan, Consequently there is a greater proportion of brain behind the meatus auditoriiis externus in the Chimimnzee than in the Orang-cetan. Behind the condyle of the lower jaw there is, in the glenoid cavity of the temporal bone, a process, of which the rudiment exists also in man, affording a sup- port for the jaw to guard against a backward dislocation. The frontal bone is single as in man, but distinguished by large projecting supra-orbital ridges, which form a sort of line of demarcation between the cranium and the face. The squamous portion of the occipital bone is of considerable extent, more convex than in the Or«?/g, and consequently more like that of the human subject. • The squamous portions of the temporal bone extend over a smaller portion of the sides of the cranium than in man, and their superior margin, instead of forming a convex curve, is almost a straight line. The mastoid processes are represented on either side by a mere ridge of bone, and the styloid processes by small tubercles. The condyloid processes of the occipital bone are proportionally smaller than in the human sub- ject. The foramen magnum is situated in the middle of the posterior third of the basis cranii^ and its plane is inclined upwards from the anterior margin at an angle of 5° from the plane of the basilar process; there are no posterior condyloid foramina but the anterior condyloid foramina, the foramina jugularia, stylo-mastoidea , carotica, spinosa, and ovalia, are in nearly the same relative position as in man ; the principal difference is in the greater distance between the foramen caroticiim and the foramen ovale, in consequence of the greater antero-posterior extent of the petrous bone. In consequence of the proximity of the foramen magnum to the posterior margin of the skull, a considerable extent intervenes between it and the posterior margin of the bony palate ; this is occupied by the large development of the petrous bones, and a corresponding extent of the basilar element of the occipital. The antero-posterior diameter of the bony palate, in like manner, greatly exceeds that of the corresponding part of the human skull. The zygomatic arches are op- posite the middle third of the skull, as seen from below, while in the human cranium they are included in the anterior moiety. The form of the basis cranii differs generally from the bimanoiis, and manifests the qiiadru- manous type, in its greater length, in its flat- ness, in the small extent of the receptacle for the brain behind the foramen magnum, in its contraction between the zygomata, and in the large size, and especially the anterior develop- ment, of the bony palate. A character, by which the Chimpanzee ap- proximates more closely than the Orang to the human subject, is presented by the nasal bone, which projects, in a slightly arched form, beyond the interorbital plane, while a trace of its original separation into two lateral elements remains at the lower margin of the consolidated and single bone. The ascending or nasal portion of the su- perior maxillary bone, which is of greater proportionate size than in the human subject, does not ascend vertically to the orbits, as in man and some of the lower Quadrumana, but slopes backwards, as in the Ct/nocephali and in the carnivorous mammalia, but in a less degree. The contour of the upper jaw, from the nasal aperture to the incisor teeth, is almost straight, while in the Orang it is rendered concave by the greater development of the intermaxillary bones in the anterior direction. These bones are anch}'losed to the maxillary bones in the adults of both the Chimpanzee and Orang ; but in the Chimjoanzee the anchylosis takes place at a much earlier period. In the same manner as in man the original separation remains visible, in the palate external to the foramina incisiva. The lower jaw, like the upper, is equally characterised by its strength and size in relation to the entire skull ; the symphysis or chin recedes ; but the depth of the jaw in front is less than in the Orang-cetan. The ramus of the jaw forms a more open angle with the body than in the Orang-cetan, and thus more nearly resembles the human struc- ture. The dental formula of the Chimpanzee is as I stated before. The teeth approximate in their proportionate size much more nearly than those of the Orang-cetan to the human teeth, but they differ by the absence of un- broken proximity. A well-marked interval separates the upper laniaries from the con- tiguous incisors, and the lower laniaries are removed by a smaller interval from the con- tiguous bicuspides ; these intervals admit the QUADRUMANA. 199 apices of the large laniaries respectively of the opposite jaw, when the mouth is closed. In the description of all these peculiarities of the skull of the Chimpanzee, I have been somewhat length}-, wishing to give an abstract of the excellent paper by Owen * ; and I deemed it necessary to do so, because the Chimpanzee may be considered as the typical link of a chain uniting mankind with the lower animals. By the minute exhibition of all its characters, it is evident that it has a great deal of analogy with the form of man, but that, on the other side, it is removed from man by its more imperfect structure. This infei'iority becomes gradually more ap- parent in the skull of the other monkeys, as may be seen by the brief statement of their principal forms. In the skull of the Orang-cetan (Jig. 117) Fig. 117. Skull of the Orang-cetan. (^After Owen.) the approximation to the Carnivora appears principally in the interparietal and occipital crests, which, as I have proved in my Reck. dfAnat. Comp. sur le Chimpanse, increases with the general growth of the animal ; in the less large interorbital space ; in the sometimes single, sometimes double nasal bone, which never projects, as in the Chimpanzee, beyond the plane of the nasal process of the superior maxillary bones ; in the facial suture of the intermaxillary bone, remaining till the per- manent teeth are almost fully developed ; in the more prominent maxillary and intermaxil- lary bones ; in the stronger teeth ; in the higher and longer lower jaw ; and in the more depressed chin. It is remarkable that the * Fearing I might give an inaccurate account, I have employed, for the most part, the very words of that experienced anatomist, feeling persuaded that, especially for a foreigner, it would be difficult to give a more elegant and more accurate description than he has done. I confess myself guilty of the same plagiarism in some other points of the osteology of the Chimpanzee and Orang-oetan. analogy with the human form is more striking in the young than in the old Chimpanzee and Orang-cetan. In the old, the face, and principally the maxillary bones, grow larger, by which the brutish appearance of the skull becomes greater. On the first aspect, this seems a deviation from a general rule, but it is not so; for in the human subject similar modifications of the skull by age may be observed. In advancing age the face of the child becomes gradually larger and higher, and the receptacle for the brain proportionally smaller, in the same manner as in the Orang- cetan, but in a less degree. In the skull of the Siamang (fig, ] 18), the Fig. 118. Skull of the Siamang. (^Original from the museum of Prof. G. Vrolik.) analogy with the human form is, in some parts, greater than in the Orang-cetan. The superciliary ridges, and the semicircular bound- ary for the insertion of the temporal muscle, are much developed, and the skull is very flat, as in the Chimpanzee, but the interorbital space is large, as in the human subject ; the nasal bone is double in young animals, single in the old, but much broader than in the Chimpanzee or Orang-cetan ; the facial part of the skull is broad, and not so prominent as in the two preceding species ; the chin has a vertical direction and rounded form ; the coronoidal apophysis of the lower jaw is not very high. By all this the skull of the Siamang approaches to that of the human subject, but it shows nevertheless its infe- riority by tY\e foramen occipitale mngmnn being placed more backwards. In this and the other Gibbons a sti'iking character is given, by the swollen appearance of the posterior wall of the orbit, produced by the convexity of the orbital part of the zygomatic bone. The ala magna of the sphenoid bone contril;utes nothing to the formation of the orbit, being bent backwards. The superior margin of the squamous portion of the temporal bone is straight, as in the Chimpanzee, the Orang-oetany and, in general, as in all the monkeys. The Semnopitheci form a sort of transition from these anthropomorphous species to the lower monkeys. Their face is not very pro- minent ; the facial suture of the intermaxillary bone continues to exist in the adult, but dis- appears in the very old ; the coronal suture is prolonged in a point between the two parietal o 4 200 QUADRUMANA. bones, and meets there the sagittal suture, which is evidently a proof of inferiority, as A. G. Otto indicated a few years ago.* The depressed chin, the narrowness of the inter- orbital space, the single nasal bone in most of the genus, are the other characters by which the Semnopitheci show their lower rank in the animal kingdom. This lower rank, however, is much more evident in the Inui, in which the prominent bony muzzle, the elevated superciliary ridges, the depressed forehead, the flat receptacle for the brain, the chin falling backwards, the long and narrow palate, the single nasal bone, ap- proach to the form of many Carnivora, and manifest an evident inferiority. The facial suture of the intermaxillary crone disappears only in the very old ones. All this is still more apparent in the Inuus sylvanus {fig. 1 19), Fig, 119. 8hdl of Inuus sylvanus. (^Original, Mus. Zoot Soc. Amsterdam.) in which the face is more flat and the chin more depressed than in the other species. In the skull of an adult, I found the facial suture of the intermaxillary bone almost obliterated. In no monkeys, after all, the expression of animality is more distinct than in the CT/nO" cephali(fig. 120), in which the contracted fore- Fig. 120. Skull of Cynocephalus porcarius. (^Original, Mus. G. Vrolik.) head, the flattened occiput, the formidable canine teeth, the huge jaws, the strong ex- panded zygomatic arches, the largely deve- loped cranial ridges, the projecting superciliar tuberosities, and the small extension of the cerebral cavity, contribute to form a hideous aspect, principally in the Mandrill, in which * A. G. Otto, De rarioribus quibusdam Sceleti humani cum Animalium Sceleto Analogiis. Vratis- lavise, 1839, p. 9. the convex supermaxillary ridges give an ad- ditional feature to their ferocious appearance. For the description of the skeleton of the monkeys of the old world, we shall select the two extremes, the Chimpanzee and the Mandrill, {figs. 121 and 122). The vertebral column of Fig. 121. Skeleton of tlie Cliimpanzee. (After Owen.) the C/iimpa7izee pvesentshut few deviations from that of the human subject. The number of true vertebrcB is the same, but an additional pair of ribs takes one from the lumbar, to be added to the dorsal or costal series. The spines of the seven cervical vertebrae are simple and elongated, not short and bifurcated as in the human subject; that of the third vertebra is the shortest, with the exception of the atlas, where the spine is wanting. The bodies of the lumbar vertebrcs are proportion- ally smaller in the Chimpanzee than in man, where they are enlarged in reference to his erect position. This difference from the bi- QUADRUMANA. 201 manous type is manifested still more strongly by the narrowness and length of the saa^um, its smaller curvature, and its parallelism with the spine. A peculiarity is observable in the position of the last lumbar vertebra with rela- tion to the iliac bones ; these rise on either side to, and are partially joined with that ver- tebra, so that it might almost be reckoned as belonging to the sacral series. The false vertebrcB, viz. the sacral and coc- cygeal, are seven in number. Of these, only the first two have their transverse processes fully developed, and united to the iliac bones ; and hence the trunk is less firmly connected with the pelvic arch, and is consequently more in need of additional support from the anterior extremities than in man. This pecu- liarity, together with the general disposition of the vertebral column of the Chimpanzee, shows that the animal is not designed to walk, as the human subject, on his hinder legs, but that it is chiefly a quadruped. Fig. 122. Skeleton of the Mandrill. (^Origin In the same way, the pelvis of the CMju- panzee differs from that of man in all those particulars which characterise the Qnadruivnna, and which relate to the imperfection of their means of maintaining the erect position. The ! iliac bones are long, straight, and expanded i above the outside, but narrow in proportion I to their length ; the posterior surface is con- cave, for the location of the glutaei muscles ; the anterior surface nearly flat, and stretching outwards, almost parallel with the plane of the sacrum. The whole pelvis is placed more I in a line with the spine, than in man ; its su- :i perior aperture is elongated and narrow, so ■j that the whole of the sacrum and coccyx is |i visible on a front view. The tuberosities of ij the ischia are broad, thick, and curved out- \\ wards. The pubic bones are broad and deep, ^1 but flattened from before backwards. In this general conformity with the quadru- I manous type, there is, however, a provision I for a more extended adherence of the glutaei il, Mus. Zool. Soc. Amsterdam.') muscles in a greater breadth of the ilia, be- tween the superior spinous processes, which also incline forwards more than is observable in the lower genera of Simice ; and it may thence be inferred that the semi-erect position is the most easily maintained in the Chim- j)anzee. In the Mandrill the general disposition of the vertebral column is much more remote from the form of man, and approximates to the form of the Carnivorous Mammalia. In the cervical vertebrae, the transverse pro- cesses have a triangular form, and offer an- teriorly a vertical ridge similar to that which appears in most of the Mammalia as a distinct apophysis. In the dorsal vertebrae, the spinal processes of the nine anterior are inclined backwards, of the three posterior forwards : consequently they offer an opposite direction, which is wanted in the vertebral column of the human subject and in the higher genera of monkeys, but which exists generally in the 202 QUADRUMANA. four-footed Mammalia. The same analogy with these appears in the disposition of the lumbar vertebrae. Their number is six or seven, and their articular or oblique processes are bifurcated, and give origin to a styloid process, which serves to increase the strength of the lumbar part of the vertebral column, and is therefore to be found in the greater number of the quadrupeds. There is no true sacrum ; but two or three sacral vertebrae, forming a conical series, are separately united to the iliac bones, in the same manner as in the Carnivora. The pelvis is much more elongated and cylindrical than in the Ckhnpanzee, and consequently more approximate to the type of the quadrupeds. The iliac bones are very long, but narrow, with a posterior concave, and an anterior convex surface. The pubic symphysis is very long ; the ischiatic tuberosities are curved outwards, broad, and form a semicircular surface for the insertion of the ischial callo- sities, which serve the Mandrills as a secure and commodious seat, when they are disposed to sleep or repose after the violent and fa- tiguing motions which they habitually exe- cute. By all these peculiarities it is manifest that the Mandrill is much more remote from man than the Chimpanzee, and a superficial examination of the two skeletons (^g.y. 121 and 122) will be sufficient to show the great differ- ence existing between them. Between these two extremes are ranged the other genera of Monkeys of the Old World, as I have stated in the above-mentioned book. I take the liberty to refer to it for more details, and principally for the gradual deviation, by which the vertebral column of the Chimpanzee passes, by the intermediate forms of the Orang- cetan, the Gibbons, the Semnopiitheci, the Inui, to that of the Cynocejihali ; but I think it necessary to make an exception for the Sia- Viang, because the anthropo-morphoiis disposi- tion is more distinct in this ape than in any other, and even more than in the Chimpanzee or Orang-oetan. The ascending processes of the superior surfaces of the bodies of the cervical vertebrae ; the inclination of the spines from the fourth to the ninth dorsal vertebrae ; the number of five lumbar vertebrae ; their in- creasing strength and breadth backwards ; the form of their transverse and spinal processes ; the true sacrum, and the quite anthropo- morphous disposition of the iliac bones, make the vertebral column of the Siamang (as may be seen in^;%. 123) approach the most to that of man. The same conformity with man ap- pears in the sternum of the Siamajig. It is composed of the same portions as the ster- num of man, viz. the manubrium, the body of the bone, and the xyphoidal appendix ; but it is proportionally broader and shorter, and the body consists of two symmetrical parts. In the sternum of the Chimpanzee there is more analogy with the structure in inferior ani- mals. It has a separate manubrium, want- ing the semi-limar incision of that of man. It is connected with a series of osseous seg- ments, and with a xyphoid appendix. In the Orang-oetan all these segments, and some- times also the manubrium, are separated in two symmetrical parts. Consequently it offers the division proper to the sternum of man, in Fig, 123. Skeleton of the Siamang. (^Original, JIus. Vrolik.) the earliest periods of foetal life, but con- tinuing to exist sometimes by deformity, as has been proved by Otto* and Breschet.f In the other Monkeys, and principally in the MandriU, there is no conformity at all v. ith the sternum of man. The manubrium is * Otto, hi the above-mentioned pamphlet. f G. Brescliet, Rech. sur diffe'rentes pieces du Squelette des Aniraaux Yertebres; Ann. de Sc. Natur. Aout, 1838. QUADRUMANA. 203 wanted, and the rest of the sternum composed of as many segments or stcrnebrce (Blain- ville), as there are true ribs. The form of the ribs has much analogy in the anthrojjo-morphous Apes with the ribs of vian. Their number corresponds with that of the dorsal vertebrae ; consequently it is 13 in the Chimpanzee and in the Siamang, 14 in some Gibbons, 12 in the Orang-oetan and in the greater number of the other species of monkeys. They form a very ample and con- vex thorax in the Chimpanzee, the Orang-oetan, and the Gibbonsy which becomes gradually more narrow and compressed in the Semno- pitheci, the Inui, and Cynocephali. In the size and length of the anterior extremities, the Orang-oetan and the Siamang are remote from man, to whom the Chimpanzee ap- proaches a little more. In the Orang-cetan and in the Siamang they are so long that they touch the ground, and in the quadruped position of the trunk the Orang-oetan is forced to curve the hands outwards, and to support itself upon their dorsal surfaces. In the Chimpanzee, sustaining himself in a semi-erect position, they touch the superior third part of the fibula. In the erect position of man they descend not lower than the third inferior part of the thigh. Consequently the Chim- panzee, the Orang-oetan, and the Gibbons, exhibit, as permanent conditions, proportions of the posterior extremities, w^hich in the human subject are transitory, and proper to the early periods of foetal life. It is, however, according to the observations of Owen, a remarkable fact, that in the young Chimpan- zee the lower extremities, instead of being shorter, in relation to the trunk, are longer, their adult proportions arising from the in- creased development of the trunk and ante- rior extremities, which are thus made fit for the vigorous acts of climbing. In the Chimpanzee the clavicle exhibits the same sigmoid curve as in vian, but the sca- pula deviates from the human form by being narrower, in proportion to its length, by the spine running more in the direction of the axis of the trunk, and by being situated more towards the middle of the scapula, and more perpendicular to its plane. The acromion process Is longer and narrower than in man. In the Orang-oetan the scapula is broader and more analogous to the scapula of man, but its spine is inclined towards the superior costa; its acromion is narrower and clavi- form, and its coracoid process has a greater inclination downwards. This inclination is an indication of inferiority manifested in all the lower species of monkeys, but it is wanted in the Chimpanzee and in the Gibbons, in which the coracoid process has the same direction as in man. That it is an indication of being placed on a lower scale is proved by the fact, that in all the Mammalia with cla- vicles the same disposition is observed. The humerus is long in the Chimpanzee, and in all the other long-armed Apes, in which also the fore-arm is longer than the humerus, and composed of two bones, radius and ulna. curved in two opposite directions, so that the space existing between them becomes very large. In the Mandrill, and all the other monkeys of the Old World, the disproportion between the anterior and posterior extremi- ties exists no more ; or if there is a dispro- portion, it is produced by the greater length of the posterior extremities. The humerus and forearm are in them almost of the same length. The hand of the Chimjwnzee is com- posed of the same number of bones as the hand of man ; but the trapezium and trape- zoides are proportionally smaller, while the OS jnsiforme is of larger dimensions, being nearly equal to the os magnum. The small size of the trapezium evidently relates to the shortness of the thumb, which it supports. The little finger is also shorter, as compared with the other fingers, than in the human subject. The metacarpal bones are chiefly remarkable for their length ; the phalanges, both for their length and their interior curva- ture. The hand is thus admirably formed for clasping the thick boughs of forest trees. On the sides of the anterior surfaces of the first and second phalanges, there are ridges for the insertion of the ligaments for the tendons. The general opinion is, that the carpus of the Orang-oetan offers the same number of bones as in man and in the Chimpanzee ; but I have proved in my Rech. d' Anatomic comparee sur le Chimpanse, that there is in the Orang- oetan an additional bone, situated between the two series of carpal bones (/g. 124.), which I found also in the Gibbons, and which seems to exist in all the lower monkeys. De Blain- viLLE has described it by the name of os intermediaire. Its existence in the Orang- oetan, and its absence in the Chimpanzee, are facts of some importance, as they prove that also in this point of organisation the Chim- panzee is superior to the Orang-oetan. Another character of the hand of the Orang- oetan, and of all the other Monkeys of the Old World, is the length and the narrowness of the metacarpus, and the length of the digital pha- langes, with the comparative shortness and backward position of the thumb. The sole ex- ception I know is in the Siamang, whose hand represents almost the hand of man, on a more elongated scale. The trapezium is not situated on the same level as the other bones of the carpus ; consequently the thumb, the bones of which are comparatively longer and thicker than in the Chimpanzee or Orang-oetan, can be opposed to the other fingers. "The middle finger is the longest, and the metacarpal bones decrease from the index to the httle finder in the same manner as in man. In the Mandrill, on the contrary, the four metacarpal bones of the fingers are of the same length, and the middle finger is not longer than the other. Thereby the forehand loses all its analosy with the hand of man, and approaches to the form of the paws in the Caryiivora. In the Semnopitheci the thumbs offer a dispropor- tionate shortness, which scarcely surpass the rudimentary form, and prepare us in some 204 QUADRUMANA. degree to anticipate its total absence in the to account for that sedateness of character Colobi. This defect necessarily impairs the and indisposition to violent activity for which function of prehension in the Semno2ntheci, they are so remarkable, and, according to the views of Ogilby, helps Fig. 124. a, scaphoid ; h, semilunar ; form ; A, intennediaire bone ; Carpus of the Orang-cetan. ( W. Vrolik.') c, triquetrum ; d, trapezium ; e, trapezoides ; /, os magnum ; g, unci- i, OS sesamoideum for the tendon of the abductor longus poUicis. The femur of the Chimpanzee is slightly bent in the anterior direction, as in the human subject ; the neck of the bone has the same comparative length, but stands out more ob- liquely to the shaft. The whole of the bone is flatter or more compressed from before backwards. The head of the femur is at- tached to the acetabulum by the ligamentum teres, which is most remarkable, because it is wanting in the Orang-cetan, and exists in the other monkeys. The tibia in the Chimpanzee is proportionally thicker at the upper end, and the fibida considerably stronger at the lower end than in man ; the interosseous space is wider, and the anterior convexity of both bones may be perceived to be slightly increased. The patellae are proportionally smaller. The relative size and position of the tarsal bones more nearly correspond to the same in the human subject than is found in any other quadrumanous animals ; but they deviate nevertheless as much as is necessary to produce that position of the foot which is adopted for climbing, viz. on the exterior edge of the foot, with the sole bent up, and inwards. The os calcis is relatively weak, as compared with that of man, being more com- pressed from one side to the other, and smaller in all its dimensions ; but it projects backwards more than in the Orang-cetan or in the lower SimicB. From the inclination of the tarsus to rest on its outer edge, the os naviculare is further developed downwards, so as to pro- ject considerably below the bones of the same row, without inconvenience from pressure on the sole. The internal cuneiform bone has a corresponding inclination, and thus the hallux is attached to the tarsus, in a position best adapted for its being opposed against the other toes. The whole foot of the Chimpanzee is relatively longer and narrower than in man; and the digital phalanges are more inflected towards the sole. All these deviations are still more apparent in the Orang-cetan, as I have stated in my Recherches Anatomic comp. sur le Chimpanse ; in which I compared the anatomical disposition and the physiological action of the foot of the Oravg-cetan with those of club-foot (pes varus^. There can be no doubt that this direction of the foot ren- ders it unfit to support the animal upon a level surface, while it is on the contrary very convenient for the action of climbing. For the same reason the hallux or the thumb of the posterior extremities has a great deal of mobility. I saw many times the two Orangs- cetan of our gardens at Amsterdam grasp objects with the hinder hand, scarcely with less agility and ability than with the fore- hand. The frequency of these movements of the hinder thumb, and the friction it has to support, when the animal climbs, seem to be the cause why its nail and ungual phalanx sometimes become atrophied, as I have proved by many examples, and as may be concluded also from the perusal of the works of Camper, Temminck, Owen, Vosmaer, and Oskamp. In the Siaijjang, and in the other Gibbons, the foot approaches more to the human than in the Chimpanzee and Orang-cetan. The QUADRUMAXA. 205 calcaneura is very strong, and the hinder thumb is, like the hallux of man, the thickest of all the toes. In the other monkeys of the Old World, the hinder hand loses entirely its analogy with the foot of the human subject. The tarsus is long and narrow, and the hallux acquires more and more the form of a small thumb, removed from the other toes, and giving to the foot some resemblance with the hand ; from which the name of four-handed Mammalia or Quadrumana is derived. Myology. — If the osteology of the Mon- keys of the Old World affords us the oppor- tunity of making some interesting remarks, their myology will certainly seem not less important. But it will be almost impossible to give an accurate description of their muscles in the small space allowed to me. I therefore think it proper to confine myself to those statements, by which the same gradual inferiority as in the bony framework may be confirmed, and I beg leave to refer to my Jteck. d'Anat. comp. siir le Chimpanse for a more minute description. One of the very striking peculiarities of the myology of the monkeys is the existence of a distinct pla- tysma myoides, which I found in all those I had the opportunity to dissect. It is an im- portant conformity with the structure ofman, in whom this muscle represents the larger subcutaneous muscles of the other mammalia. The sterna cleido-mastoidem offers an in- cipient indication of a lower station, by the cla\-icular fascicle being wanting in the Imd and the Cynocephali. In the digastricus maxillcB inferioris there is, especially in the Inui and Cynocephali, a reunion between the two anterior fascicles or ventres^ by which the power of the muscle for the abduction of the lower jaw must be strongly augmented. The other muscles si- tuated between the hyoid and the chin re- semble in the Chimpanzee^ those of man, but in the other monkeys they show marks of a lower organisation. According to the ob- servations of E. Burdach and myself, the hyo-thyreoidewt and hyo-glossus are united in one, in the Inui and the Cynocephali. In the infra-hyoidian muscles, the only dif- ference from man is, that the intermediate tendon of the omo-hyoideuSy which exists in the Chimpanzee as in man, disappears in the Imd and in the Cynocephali, and that in these monkeys the inferior portions of the stemo-hyoidei and sterno-thyroidei are united together. In the latissimus dorsi, an interesting transition to the form of the other mammalia is observed, even in the Chimpanzee, by a pro- longation attached to the olecranon. It seems connected with the power that must be per- formed by this muscle, in the action of clin)b- ing. According to my observations in various animals, the insertion of this prolongation differs according to the variety of movements, performed by the anterior extremities. The rhomhoideus of the Chimpanzee has the same form and situation as in man, but in the Inui and the Cynocephali it goes to the oc- ciput, in which its insertion serves to sustain the head, in the quadruped progressive motion of these animals. In the Inui and in the Cynocephali, but not in the Chimpanzee, there is a conformity with the form of the large Carnivora, in the existence of the acromio-trachelien (Cuv.), acroinio-basilaire (Vicq d'Azyr), coming from the transverse processes of the first cervical vertebrae, and inserted into the spine of the scapula. Its function seems to be to bring the scapula more strongly forwards. The pectoralis magnm, p. brevis, suhclavius, and serratus anticus magnus of the Chimpanzee^ the Orang-cetan, and the G/'6(6o«.s, resemble those of man. The only difference is that, accord- ing to the obser\'ations of Sandifort, the pec- toralis magnus is divided in the adult Orang- aetan into a large number of fascicles, in the intervals of which are situated the digitiform prolongations of the enornxjus laryngeal pouch. But in the Mandrill the pectoralis magnus acquires more analogy with the large quadrupeds, by its greater extension, and its separation into three great fascicles, of which one comes from the posterior part of the thorax. In the muscles of the anterior ex- tremities the general distribution and form are the same as in man. An interesting de- viation is given by the Hylobates leuciscuSy in which the caput breve m. bicipitis takes origin, from the insertion of the pectoralis magnus. Can this peculiarity be connected with the velocity of their movements, when they swing themselves from one branch to another ? Du- VAUCEL affirms that they will on these occa- sions leap, with comparative ease, to the surprising distance of forty or fifty feet. About the extensores of the fingers, a lower form may be observed in the extensor digiti indicis, or m. indicator., which is not a separate muscle, but only a portion of the extensor communis. Consequently the fore-finger, or index, must want the so characteristic separate move- ments, by which we are accustomed to call the attention upon a subject. The imper- fection of this muscle is certainly in relation with the lower psychical condition of the animal. In the Inui and the Mandrill the extensores are still more imperfect, by the division of the extensor digiti minimi, which gives a tendinous insertion to the annular or fourth finger. It is, as I showed in my work upon the Chimpanzee, a transition to the form of the Carnivora. The eight muscles of the thumb exist in the Chimpanzee and in the Hylobates leuciscus ; but in the Orang-cetan and in the Mandrill the abductor longus and the extensor brevis poUicis are united in their mus- cular portions, while the tendons remain se- parate, and in the Inui there is but one muscle, giving two tendons, which are united at their extremities. This is a distinct transi- tion to the form of the Carnivora. I have found this single muscle in all those which possess a thumb. The small muscles of the thumb, viz. the abductor brevis, the flexor brevis, the adductor, and the opponens, exist in all the monkeys of the Old World, but on a smaller scale than in man. They have also 206 QUADRUMANA. the three small muscles for the little finger on the opposite edge of the hand. The con- sequence of all this is, that the hand of the monkeys of the Old World approaches to the perfection of the human hand, from which it differs by the length and the narrowness of the palm of the hand, the length of the fingers, the backward position of the imperfect thumb, and a less variety of movements. For the physiological results which can be derived from this difference, I refer to my Rech. d'Anat. comp. siir le Chhwpanse, p. S-i. The muscles of the posterior extremities differ more from those of the human subject. The glutcEi are feeble, and inserted very low on the femur; the gracilis is much broader than in man, and inserted very low in the tibia ; the same is the case with the semitendinosiis, the semi- membranosus, and the biceps femoris. The result of this low insertion must be, that the knee can only be maintained in a bent, and consequently the trunk in a semi-erect at- titude. The gastrocnemius and soIcbus remain sepa- rate until their insertion in the calcaneum, where they unite to form one tendon. They are flatter than in man, and consequently do not form the calf of the leg, which is so cha- racteristic in man. There is a plantaris^ as in man. The monkeys seem to be the only brute animals which possess it. The flexor magnus of the great toe or thumb of the posterior extremities is not confined to this toe, but gives tendons to the other toes. Consequently it combines its action with that of the flexor magnus 4 digit, pedis. The monkeys possess also a flexor brevis, lumbricales , an abductor and adductor hallucis, a flexor brevis, adductor brevis digiti minimiy pei'onceus longus and brevis, and tibialis posticus. All the muscles on the sole of the foot are more isolated than in man, and consequently they produce more distinct and separate movements for the digits, and prin- cipally for the hinder thumb. They have no peroncBus tertius, but the tibialis anticus differs from the same in man, by its separation into two fascicles, of which the inner seems to act as a tibialis anticus, while the outer is a long abductor hallucis. I found this disposition in all the monkeys I had the opportunity to dissect, and it is also confirmed by the observations of E. Burdach. The last myological peculiarity which I shall mention is, that the tendon of the ex- tensor communis longus quatuor digitorum is surrounded and fixed by a ligamentous loop, about which I can add the historical pecu- liarity, that this ligament, hitherto unknown, has been described in the same year, and per- haps in the same month, by A. Retzius in Stockholm, and by myself in Amsterdam.* * A. Eetzius, Bemerk. iieb. ein Schleuderformiges Band in dem Sinus tarsi des INIenschen u. mehrere Thiere in J. Muller, Arcli. Berlin, Jahrg. 1841, Th. V. p. 497. W. Vrolik, Rech. d'Anat. Comp. sur le Chimpanse, p. 22. tab. v. fig. 2. Neurology. — The brain of the monkeys of the Old World represents an imperfect outline of the brain of man. By the form and the number of convolutions, Leuret * proved that it approaches to the brain of the human subject ; but however great this analogy may be, there remains, however, no doubt that there are some typical differences between the brain of man and of the monkeys, and that from the Chimpanzee to the Cynocephali, the gradual tendency to inferiority is as manifest as in the other points of organisation. We still want perfect representations of the brain of the first, but we may supply this defect by drawings of the brain of Xhe Orang-cetan, of which TiEDEMANx has represented the basis, Saxdifort the superior surface, and I a ver- tical section. (Figs. 125, 126, 127.) If we Fig. 125. Basis of the brain of the Orang-cetan. (After Tiedemann.) Fig.\26. Superior surface of the brain of the Orang-cetan. (After Sandifort.) * F. Leiu-et, Anat. Comp. du Systeme nen-eux conside're' dans ses rapports avec I'intelligence. Paris, 1839, 8vo. Vertical section of the brain of the Orang-cetan. {After W. Vrolik.) compare these distinct views of the brain of the Orang-cetan with those of the Baboon represented by Leuret * {figs. 128, 129, 130), QUADRUMANA. 207 the inferiority of these to the Orang-oetan is so manifest, that it needs scarcely any further explanation. In the first instance, it appears that the brain of the Cynocejyhalns, and, ac- cording to the observations of Tiedemann, we could say the same for all the monkeys inferior to the Chimpanzee, the Orang-oetan^ and the Gibbons, differs from the brain of man : 1. By a greater breadth in proportion to the length, and consequently by a less elhptical and more triangular form. 2. By less development of the hemispheres of the brain, which do not cover the whole cerebellum. 3. By a smaller number and greater sym- metry of the convolutions, and less deep anfractuosities. 4. By less development of the corpus striae turn, thalamus nervorum opticorum, corpus cal" losum, and septum lucidum. Figs. 128, 129, 130. Views of the brain of the Baboon. {After Leuret.^ 5. By the want of digitations on the convex margin of the comu Ammonis. ' 6. By the want of the eminentia digitalis (pes Hippocampi ininor). 7. By the disposition of the corpora albi- cantia, which are united in one mass. 8. By the absence of calculous granulations in the glandula pinealis. 9. By less development of the cerebellum and of the pons Varolii. * F. Leuret, Anat. Comp. du System e nei-veux considcre dans ses rapports avec I'lntelligence, Paris, 1839, 8vo. All these manifestations of inferiority are not so distinct in the brain of the Orang-cetan, which approaches more to that of man. This approximation consists in : 1. The more elliptic, and consequently more human-like form of the brain. It is a most interesting fact, that the deviation, in the descending line, begins already in the Gibbons, the brain of which has a more triangular form, and less developed anterior lobes, than the brain of the Orang-oetan. 2. The larger cerebral hemispheres, which are protracted behind the cerebellum. 208 QUADRUMANA. 3. The existence of two separate corpora viammillaria, which I found also in the Hylo- hates leuciscus, and which Sandifort repre- sented in the Siamang. But they are in these less developed than in the Orang-cetan. 4. The presence of digitations on the cornu Ammonis. 5. More numerous convolutions and deeper anfractuosities. 6. A larger cerebellum. In all these peculiarities, the brain of the Orang-cetan is superior to that of other mon- keys, and still more so to that of the Gibbons, which offer otherwise so much analogy with it. The plate of Sandifort, representing the brain of the Siamang, and my dissection of the Hylohates leuciscus, have proved, that in the Gibbons the convolutions are not so numerous ; the anfractuosities not so deep, their symmetry greater ; the cerebral hemi- spheres less developed ; the cerebellum small- er; the jt>0725 Varolii less distinct; the cornu Ammonis without digitations. This greater perfection of the brain of the Orang-cetan is evidently in accordance with the more eminent intellectual faculties of the Orang-cetan, while, according to the observations of Duvaucel and of S. Muller, the Siamang and the other Gibbons are very stupid. But if, on one side, this superiority of the brain of the Orang-cetan, with which the Chimpanzee seems to have a great deal of analogy, cannot be a subject of controversy amongst anatomists, they would however go too far by saying, that the brain of both is in all points similar to that of man. The following differences may be indi- cated : 1 . The mass of the brain, in proportion to the volume of the body, is less in these Apes than in Man. 2. The cerebral hemispheres are less deve- loped, and not so much protracted backwards. 3. The nerves are thicker in proportion to the circumference of the brain. 4. The convolutions are not so numerous, and the anfractuosities less deep. 5. The coi-jms calloswn is not so much ex- tended backwards. About the nerves of the Monkeys, T shall but mention one very interesting modifi- cation, which I observed in the no-vus acces- sorius WiLLisii of the Chimpanzee. It is divided into two branches, as in man, but the internal is not united with the vagus, as it penetrates separately into the larynx. This very peculiar ramification seems to confirm the opinion of Bischoff *, that the internal branch of the n. accessorius Willisii forms partly the n. laryngeus superior. About the organs of sense there is not much to say. The eye approaches much to the eye of the human subject, by the existence of the yellow spot on the retina, but it differs by a more thin sclerotica. The ears of the higher order of monkeys resemble much the same organs in the human subject, from which they differ * L. W. T. Bischoff, Nena accessorii Willisii^ Anat. et Physiol. Darmstadii, 1832. only by a less developed lohulus. The tongue is short, broad, and round, as in man, but it becomes long and narrow in the Inui, and still more so in the Cynocephali. Angeiology. — In the distribution of the vessels and the form of the heart, the mon- keys of the Old World offer a great analogy with the disposition of the same parts in the human subject. But few differences can be mentioned. In the trunks arising from the arcus aortcB, the superior order of monkeys, as the Chimpanzee and adult Orang-cetan, offer the same number and distribution as in Man ; but in the Semnojntheci, the Macaci, and Cy- nocephali, there is a commencement of a de- scending scale in the disposition of the A. innominata, which divides into three branches, viz., the right subclavian and the two carotids, in the same manner as in the Marsupials and Carnivora. It is interesting, that I found also this distribution in four young Orangs-oetan, but that Sandifort observed in the adult the human-like division. In the other ramifi- cations, the resemblance to those of man is very great. The plates of descriptive anatomy which I published on the Chimpanzee, will be sufficient to prove the truth of this assertion. Splanchnology. — No parts of the ana- tomy of the monkeys are, perhaps, more inter- esting than the pouches of the larynx. I have published a great number of observations about them, by which is proved : 1. that they exist in the Chimpanzee, the Orang-cetan, the Siamang, the Semnopitheci, Cercopitheci, Inui, and the Cynocephali-, 2. that they are larger in the males than in the females ; 3. that they grow with the age of the animal, and are consequently the largest in the most aged ; 4. that they are chiefly a dilatation of the laryngeal ventricles in the Chimpanzee and in the Orang-cetan, but that in the other monkeys they are in direct communication with the cavity of the larynx, by an aperture at the basis of the epiglottis ; o. and that they are wanting in the Gibbons, the Cercopithecus radiatus, the Cercopithecus mona and Cynocephalus porcarius. It is very difficult to derive any physiological conclusion from all these anatomical state- ments. The most probable hypothesis seems to be, that these receptacles of air, which send their prolongations between all the mus- cular fascicles (^fig. 131), seem to diminish the specific gravity of the body, in the action of climbing, and that they are consequently passive organs of movement. I have offered this opinion in greater detail in my work upon the Chimpanzee, and I refuted there the opinion that they were connected with the utterance of voice. The other parts of the laryngeal apparatus do not differ much from those of man, with the exception of the hyoid bone, which has much of the human form in the Chimpanzee, in the Orang-cetan, and in the Gibbons, but the basis of which is changed into a convex and elongated shield in the other monkeys, in which the laryngeal pouch opens below the epiglottis. In the form and structure of the heart and the lungs, there is no difference between the QUADRUMANA. 209 monkeys of the Old World and the human subject. Fig. 131. Laryngeal pouch of the adult Oi'ang-cetan. After Sandifort.) In the organs of digestion, there is much difference to be observed in the various spe- cies of monkeys. The Jlpes, viz. the C/iwi' panzee, the Orang-cetan, and the Gibbons^ offer much resemblance in these organs to those of vian. The stomachs of the four young Orangs- oetan, which I dissected, had quite the human form and structure. But in the adult de- scribed by Sandifort, the pyloric portion is separated from the cardiac by a very narrow constriction, and the tunics of the pyloric portion are very thick. In the coecum the resemblance to man is still more striking, by the existence of a vermiform appendix, which is separated from the intestine by a constric- tion in the Chimpanzee^ is continuous with the intestine in the Orang-cetan^ and is very small, and almost rudiraental, in the Gibbons. Consequently there is also a descending gra- dation in this organ, in the same manner as in all the other points of organisation ; for the appendix is wanting in all the other monkeys, in which the coecum is moderately large and terminates in an obtuse cone. The stomach of the other species has not the same oblong form in the transverse direction, as the sto- mach of the SimicB and of man, but acquires a more globular form, especially in the Ci/no- cephali. In this way it forms a transition to the form of the stomach in the Carnivora. A very interesting deviation is afforded by the Semnopiiheci, in which Wurmb, Otto*, and Owenf found (as I also saw confirmed in the S. maurus) a complicated form and construc- tion of the stomach, viz., its division into three portions : 1. cardiac pouch, with smooth pari- * A. "W. Otto, tieber eine neue Aflfenart, den Cerco- pithecus leucoprymmis, in Nov. Act. Acad. Caes. Leo- pold. Carol. Nat. Curios, vol. xii. p. 2. t R. Owen, on the sacculated form of Stomach as it exists in the Genus Semnopithecus. Trans. Zool. Soc. torn. i. p. 65. The paper of Wurmb is to be found in the Memoirs of the Batavian Society. VOL. IV. etes, slightly bifid at the extremity ; 2. a middle, very wide, and sacculated portion ; 3. a narrow, elongated canal, sacculated at its commencement, and of simple structure to- wards its termination. This complication of the stomach seems to be connected with the vegetable food of the Scmnopitheci, which consists only of fruits, and it is also a repe- tition of the divisions we find in the stomach of the Pleropi, the Hyrax capensis^ the Bra- dypoda, the Cetacea, and in the utmost per- fection in the Ruminantia. A curious fact connected with this sacculated division of the stomach is the existence of bezoars in the Semnopiiheci. They are said to be smaller and rounder than those produced by the goats, gazelles, and antelopes. A similar disposition of the stomach exists in the Colobi. Ruppell observed it in the Colobus gnereza, and Owen * said, that in the Colobus polycomos, the sacculation of the sto- mach is produced by the same modification of the muscular fibres as in the Semnopiiheci^ combined with a great extent of the digestive tunics. A narrow band of longitudinal fibres traverses the lesser curvature of the stomach, and a second band, commencing at the left or blind end of the cavity, puckers it up in a succession of sub-globular sacs along the greater end. The form and the size of the coecum, and the length and disposition of the intestinal canal in the Colobus^ equally corre- spond with those parts in the Semnojntheci. About the urinary and genital organs there are but few peculiarities to observe in the monkeys of the Old World. The urinary organs have the same general disposition proper to the human subject ; the male genital parts differ only by the existence of an ossi- culum penis, by the lobulated form of the glans in some species, and by the complicated structure and large development of the vesi' culcB seminales, especially in the Mandrill. In the female organs, the form and structure of the uterus are interesting : it resembles that of man, and differs from the divided and bicoj-n uterus of most of the other Mammalia. It is only by a more longitudinal, and we may say a more foetal form, that the uterus of 'the monkeys differs from the same organ of the human subject in the adult state; whereas in gestation, parturition, lactation, and in menstruation, the monkeys of the Old World offer a great deal of analogy with man- kind, as may be seen in the elegant descrip- tions which F. Cuvier gives of many species in his Hist. Nat. des Mammiferes. In the clitoris there is no bone ; at least Leuckart found none in Iniins rhesus, but he observed a bifid clitoris in Cercopithecus sabccus. Ac- cording to the observations of G. Breschet J. VAN DER HOEVEN and SCHROEDER VAN DER KoLK f, the placenta of the monkeys of the * R. Owen, Proceedings of the Zoological Society, p. ix. 1841, p. 84. t Tydsclieift von Natuurlyke geschiede nis en- physiologie intgegeven door J. van der Hoeven en W. H. de Vrese, Leyden 1837—1838, &c. &c. p. 357. G. Breschet, Rech. Anat. sur la Gestation des P 210 QUADRUMANA. Old World is separated into two lobes, united by vessels. This may be a transition to the cotyledons of the placenta in most of the Mammalia. The Second Group of Simice comprehends those of the New World, or Cebincs (SimicB 'platyrrhincB G. S. Hil), possessing a distinct character in the existence of four additional molar teeth, by which the general number of teeth is thirty- six. Their head is distinguished by a more rounded form, by nostrils situated laterally on a large nose. A long, and in some species a prehensile tail ; the want of cheek-pouches and of callosities on the but- tocks ; a smaller and less robust body, and a less malicious but more melancholy character, give a very conspicuous and distinguished physiognomy to this group. 2. Cebinve. Monkeys of the New World. The number of teeth is : incisors, — ; canines, 4 ^ — ^- ; molars, ^ — ^ = 36. 1—1 ' 6—6 They ought to be divided into two great divisions, of which the first comprehends those in which the tail is prehensile, viz., capable of grasping branches, so as to perform the office of a fifth extremity. It is naked at its extremity in some species. a. CebincB, with a prehensile tail, naked at its extremity. 1. First Genus. Mycetes. Alouatte, Singe hurleur.Vw Howler, ^ng\. Brul-aap,'Dutch. Pyramidal head, with an elevated inferior jaw, whose branches are very distant, to give room for a peculiar inflation of the basis of the hyoid bone, which communicates wnth the larynx, and seems to produce the loud and frightful bowlings. By this the anterior sur- face of the neck is swollen up, which, added to their long beard, gives these animals a hideous appearance. The teeth have the general disposition proper to the Cebince, but the canini are very strong, and therefore the space in the upper jaw between the external incisor and canine tooth is large for the reception of the canine tooth of the lower jaw. The Mycetes are drowsy and lazy in captivity. In their native woods they live in troops, and climb the trees with much agility. Spec. — M. senicidusy M.fuscus, M. niger. 2. Second Genus. Ateles. Sajoajou ordinaire. Rounded head, with a slightly prominent muzzle. The thumb imperfect, but visible in some, not visible in others. The clitoris so much developed, that it has quite the appear- ance of a penis, with a channel at its inferior surface. Those, who possess a visible thumb, have been considered by Spix as forming a distinct genus, under the name Bracliytele, but I think it not necessary to introduce this Quadrumanes, Mem. de I'Acad. de^ Sciences, s. xix. Paris, 1845. division. The species of the genus Ateles represent in America the Semnopithcci of Asia, and the Colobi of Africa. They have the same slowness of movement, and the same gravity and gentleness of manners. Their progressive motion upon a level surface is very uneasy and unsteady, while they are forced to sustain themselves upon the internal edges of their fore-hands and the external of their hinder-hands. But they climb with much agility, aiding themselves with the prehensile tail, which acts as a fi.fth extremity. Their teeth resemble those of the genus Mycetes, but the canine are not so strong, and the molar teeth rounder. They all inhabit Guiana and Brazil. Spec. — Ateles pent adactylus, A. hypoxanthus, A. paniscuSy A. arachnoides^ A. fiiliginosuSy A. marginatus. 3. Third Genus. Lagotlirix Geoffr. Caparo. Rounded head, as in the genus Ateles ; a thumb, as in Mycetes, and the tail naked at its extremity, as in both. This genus is only to be found in South America, and chiefly in Brazil. The hyoid bone is not very large. Spec. — Lagothrix Humboldtii, L. caiius. b. CebincB, with a prehensile tail covered with hair at its extremity. 4. Fourth Genus. Cebus. Sajoii. Singe pleiireWy French. Capucyn-Aap, Dutch. Rounded head and oval face, with a gentle expression. Tail thicker than in the genus Mycetes and Ateles, and less prehensile, curled at its extremity, longer than the body. Teeth not so strong as in these, especially the canine. The Cebi feed upon fruits. Their movements are graceful and gay. Their manners a mix- ture of sweetness, cleverness, agility, and lu- bricity. Their voice is a gentle whistle. The determination of the species has caused great confusion. Rengger is of opinion, that some of them are merely modifications by age of the same species. They inhabit principally Guiana. Spec. — Cebus apella, C. fatuellus^ C.robustus, C. xantho-sternos, C. capucinus, C. hypoleucus, C. albifrons. 5. Fifth Genus. Callithrix. Sagouine, Fr. Slender tail ; teeth not prominent, and short canine.* The head more elevated than in Cebus and Pithecia, but smaller, with less pro- minent zygomatic arches, and higher branches in the lower jaws. Consequently there is more room for the reception of a more com- plicated larynx. Their voice is heavier, and not so whistling as in the Cebi and Pithecice. Callithrix p)ersonatay C. amicta, C. cuprea, C. melanochir. One species C. sciurea, or sainiiri, ought to be separated fr oni the rest. W^agner makes * In his book des Dents des Mammiferes consideres comme Caracteres Zoologiques, F. Cu^ier gives the teeth of this genus as t}-pe for the Saki's by a mis- take, which he corrected in ait. Saki 7wir, Hist. Nat. d. Mammif. t. iv. edit, in folio. QUADRUMANA. 211 of it the genus Chrysothrix. Its tail is not prehensile, but depressed, and often twisted round objects. Its head is flat ; between the two orbits there is but a membranous septum, instead of a bony wall, and the glans penis is round, as in man ; while it is flat, in the form of the head of a mushroom, in the Cebi^ which have the penis in continual erection. 6. Sixth Genus. Nochthora F. Cuvier. Aotus Humboldt. Dourocoidi. Diflfers only from the genus Calliihrix by large nyctalope eyes and ears, which are partly co- vered by the skin, and by a small face. The species of this genus have nocturnal habits, and a feline physiognomy. They feed not upon fruit, as the precedent species, but on small birds and insects. In their form, noc- turnal habits, and great sensibility to light, the NochthorcB approach very much to the species of the genus Steno}n^ from which they differ in their internal structure. Their nails are straight, long, and snlcated. The dental 4, 1 1 formula is: incisors ,, canines ^ — , molars % — %. They inhabit Brazil. ^ D — 6 * Spec. — Nochthora trivirgata. 7. Seventh Genus, Pithecia. Saki. The characters of this genus consist in the bush}-, but short, prehensile, and long tail, the slender body, the large ears, the dense beard in some species, and tlie straight, but claw-Hke nails. Their incisor teeth are more prominent than in the genus Cebus. Brazil. Spec. — Pithecia SatanaSy P. rufiveyitris^ P. leucocephala, P. inusta. 8. Eighth Genus. Hapale. Ouistiti. Sahui. This genus departs more from the typical genera of monkeys of the New World than any other, inasmuch as they have only the same number of teeth as the monkeys of the Old 4 I ] World,viz.32 : incisors canines -, molars 4 1 — 1 5 5 -- — -. The nails, by being compressed and o — o pointed, assume the appearance of claws, ex- cept the thumbs of the after-hands, which have flat nails ; but the thumbs of the fore-hands, which have no flat nails, are so slightly sepa- rated from the other fingers, that it is not without hesitation that the Ouistitis are called four-handed or Quadrumana. All the species belonging to this genus live in troops in the Brazilian forests, where they spring from bough to bough, more like birds than quadru- peds. They resemble squirrels, whose form they seem to represent in South America, which possesses but one species of squirrels, Sciurus cBstuans. Their incisors, canini, and false molars, are sharp and acuminated. The inferior incisor teeth are long, narrow, and prominent. They feed upon insects, eggs, birds. Their voice is a gentle whistle, which de Humboldt* compares to the voice of some birds. He says that their larynx is similar to the inferior larynx of birds, l)ut he did not illustrate this opinion by sufficient anatomical details. The species can be divided into two groups. The first contains those in which the inferior incisors are cylindrical and the tail is annular. Hapale jacchus^ 11. ponicillatus^ II. leuco- cephalus. In the second, the inferior incisors are truncated like the mouthpiece of a pipe, and the tail is not annular. H. argentatus, H. midas, H. ursuJus, H. lahiatus, H. chrysomclas, H. rosalia, II. c1irysoj)ygus^ H. wdipiis. Osteology. — If we take a general survey of these eight genera of monkeys of the New World, we may observe in them, as well as in those of the Old World, an indication of the descending line, by which they pass into the form of the Lemuriua, and by those into the Insectivora. In this way they constitute a series, which is parallel to that of the monkeys of the Old World, the latter passing into the Carnivora, the former into the Insectivora. The truth of this assertion will be proved by a more minute examination of the skeleton. We shall first consider the skull. J. A. Wagner divided the monkeys of the New World by their skull into two great divisions. Tiie first is a pyramidal skull, in which the height is greater than the length, and in which the occiput has no posterior eminence, and the occipital foramen is situated backwards. To this division belong Mycetes., as eminently characteristic, and, in subsequent gradation, CalUthrix, Nochthora, Pithecia, and Lagothrix. The second form of skull is elongated, with a prominent muzzle, a convex occiput, and an occipital foramen, situated at the basis of the skull. Wagner refers to it the Saiiniri, offer- ing a typical pre-eminence, and subsequently Hapale, Cebus, and Ateles. In Mycetes (Jig. 132) the forehead is ele- Fig. 132, Skull of Mycetes ursinus. (^Original, Mus. Vrolik.) vated, the face flat and large ; the distance between the two orbits very great; two nasal bones ; the chin very depressed ; the lower jaw high, with distant branches, between * A. de Humboldt, Obser^^ de zoologie et d'ana- tomie comparee. Paris, 1811, vol. i. p. 8. p 2 212 QUADR UxMANA. which the inflated hyoid bone is situated. The same character is to be found in the genus Ateles. In Myceies, Lagothrix, and CaUlthrix, there is a peculiar round aperture in the orbital portion of the zygomatic bone, which has the appearance as if it were pierced in the bone by a gimlet. Mycetes, Ateles, and especially CaUithnx, afford a very striking conformity with Hylobates, in the swollen ap- pearance of the posterior wall of the orbits, produced by the convexity of the orbital part of the zygomatic bone. This is a new addi- tion to the analogy between Hylobates and Ateles. The ala magna ossis sjjhcenoidei is yet more depressed backwards than in Hylobates. In Cebus {fg. 133) the cranium is elongated, Fig. 133. Skull of Cebus apella. (^Original, Mus. Vrolik.) and uniformly round. The frontal bone is lengthened to a sharp point, which advances between the two parietals. This is, as I have said before, a manifest indication of a low^er rank. The face is not very prominent ; there are two nasal bones ; a distinct intermaxillary bone ; a rounded chin, which recedes. In Callithrix, Pitliecia, and Nuchthora, the skull has an oblong form, but it resembles very much a small human skull. The single frontal bone has a triangular form, and is distin- guished by the convexity of the orbital part. In the Saimiri the septum between the orbits is but membranous, and the interorbital space narrow ; the nasal bone is sometimes single, sometimes double ; the intermaxillary bone distinct ; the chin round and prominent ; the muzzle not protruding ; the orbital part of the zygomatic bone wants the opening proper to Ateles, Mycetes, Lagothrix, and the other species of Callithrix. This general re- semblance to the human skull is still greater in the Ouistitis. The external tuberosity of the orbit is less marked ; the interorbital sep- tum is osseous ; the muzzle not very promi- nent; the intermaxillary bone distinct, but obliterated in old age ; the nasal bones broad, short, completely separated, and consequently similar to those of man ; the chin is depressed, but rounded. Notwithstanding this general resemblance to the skull of man, Cebus, Calli- thrix, and Hapale differ in some essential points from man. The forehead is much narrower, and has its greatest elevation not laterally, but in the middle ; the occipital fora- men placed more backwards ; the muzzle more protruding. In the vertebral column of all the CebincB there is a manifest inferiority to be seen in the disposition of the cervical ver- tebrae, in which there are anterior ridges at the transverse processes, in the same manner as in the lower Mammalia. In the Cebi, the spinal process of the second cervical vertebra offers another analogy with the latter, in its elevated form, in its strength, and in its truncated posterior edge. In the Saimiri the tendency to a lower degree of pefection is still greater, by the triangular form of the transverse processes, and in the Ouistitis the spinal processes become long, acute, and di- rected backwards. The number of dorsal vertebrae varies from 13 to 14, and is con- sequently in general greater than in the monkeys of the Old World. There is oppo- site direction between the spinal processes of the three last, and the ten or eleven first dorsal vertebrae. The same disposition is observed in the Saimiri, but in the Ouistitis there is only opposition in the spinal pro- cess of the last dorsal vertebra. In Ateles and Cebus the number of lumbar vertebrae is five. The styloid processes are plainly indicated, but their spinal processes are incHned for- wards, and terminate in a recurved point, in th% same manner as in the Carnivora. In the Ouistitis the analogy with the quadru- ped form is still greater, as the styloid pro- cesses are very long. In the Nochthora the number of the lumbar vertebrae is eight, by which it approaches to Stenops. The sacrum is in the Cebince a broad quadrangular bone, with acute edges, united only by one of its spu- rious vertebrae with the iUac bones. Conse- quently the symphysis sacro-iliaca is less firm than in the higher species of monkeys. At least such is the case in the Cebi, the Ouistitis, and the Saimiri ; but in Ateles I found four spurious sacral vertebrae united with the iliac bones. The iliac bones are in general nar- rower in the Cebince than in the monkeys of the Old World : consequently the pelvis has a more cylindrical form, with a very long pubic articulation, and approaches more to the form of the pelvis in the Carnivora. The caudal vertebrce of the CebincB deserve a se- parate mention. They are true or spurious ver- tebrae. The true are but four or five, short and thick. The spurious are the longest, but become shorter at the extremity of the tail. They are onl}' united by the bodies, not by the articular processes. Chiefly remarkable are the inferior spinal processes in the an- terior caudal vertebrce, representing the letter V, and forming a canal, in which pass the vessels for the tail. These processes disap- pear in general in the posterior caudal ver- tebras, and in the monkeys with a prehensile tail the posterior vertebrae become round, tubercular bones, imitating a series of small digital phalanges. The thorax of the CebincB is compressed, and the ribs do not form the posterior arches, by which the back of man, of the Chimpanzee, and of the Orang-cetan acquire a broad and flat surface, and by which it is possible for these animals and for man to lie at full length on their back. All the QUADRUMANA. 213 species, on the contrary, which possess ischial callosities, the Gibbons among the rest, sleep and repose themselves in a sitting posture, with the arms folded across the knees, and the head reclined upon the breast, or sup- ported by the shoulder. The Cebince, in which the ischial callosities are wanting, lie down on the lateral surface of their body. The sternum is separated in the Cebince into as many segments as there are true ribs ; consequently it has quite lost the analogy with the human subject, which it has in the higher monkeys of the Old World. In the anterior extremities, the humerus of Cebns, Nochthora, Saimiri^ and Ouistiti, is similar to that of the Carnivora, by an aperture in the internal condyle, serving for the passage of the brachial artery and the median nerve, which are preserved in this manner from compression and injury, by the contraction of the muscles in the climbing motion of these Quadrumana, In the carpus of the Cebincs there are nine bones, and consequently they possess the intermediate bone, proper, as I have said, to all the monkeys, with the ex- ception of the Chimpanzee. The phalanges of the fingers and the toes are in general very long and incurvated, by which disposition they acquire a greater aptitude to grasp branches of trees, while climbing. In Ateles the fore-hand has quite lost its analogy with the hand of man, by the want of the thumb, which is only represented by an imperfect metacarpal bone. In Ateles hypoxanthus, which has a rudimental thumb. Prince Maximilian says that it consists of two phalanges, of which the first is but half as long as the second. In the Cebi, the fore-hand differs from the hand of man, by the deviation of the thumb, which is situated on the same level as the other fingers, and has the same length as the httle finger. The nails are elongated, and acquire really the form of little claws in the Ouistitis. The posterior extremities offer the general character of the posterior extremities in the monkeys ; the thumb of the hind hand is distant, and has a flat nail in the Ouistitis, while on the other fingers there are small claws. Neurology. — The brain of the Cebincs differs much in the various genera which are referred to this large division of Quadrumana. In the Cebi it is perfect, and approaches much to the brain of man, as may be seen in the drawing given by Tiedemann in his excel- lent work. But, according to the observa- tions of I. Geoffroy St. Hilaire and of myself *, there are no circonvolutions on the proportionally very large brain of the Ouistitis, and there are but few in the Saimiri, in which the anterior lobes are not so much developed as in the Cebi. To these statements Leu ret f * Comptes Rendus, t. xvi. n. 23, 1843, 12 Juin, p. 1236, and Description des Mammiferes Xouveaux, etc, in Archives du Museum, torn. ii. liv. 4., Paris, 1841, p. 515. t Comptes Rendus,tom.xvi.'n.24 p.l372. Leuck- ART agrees with these observations of I. Geoffroy St. Hilaire, saying that he found scarcely any made some objections, which have been suffi- ciently refuted by I. Geoffroy St. Hillaire. Myology. — As respects the muscles, those of the tail only deserve a special notice. They are very strong, especially the Jlexores. By them the Ateles, if it is wounded to death, remains a long time, hanging on his tail. For the same cause its tail is always inflected when in the state of rest. The Cebi sustain their body on it, if they are forced to go on their hinder legs. The other muscles seem not to differ from those of the monkeys of the Old World. The general description of these may be applied to them. Splanchnology. — The soft parts afford no material for such interesting observations as those of the monkeys of the Old World. The larynx wants in general the pouches, which I have described before. There are but two exceptions yet known, one in the Ma- rikina {Hapale rosalia), in which Cuvier and Carus state that they have found a laryngeal pouch, which, accordmg to Cuvier, communi- cates with the larynx between the thyroid and cricoid cartilages. The second exception is the Ateles jjaniscus, in which there is a mem- branous expansion behind the cricoid carti- lage. The hyoid bone of Ateles has the form proper to the monkeys of the Old World. In Cebus it approaches more to the form of 7nan, by a more truncated pyramidal and a less convex or scutiform base. The disposition of the laryngeal apparatus in the genus Mycetes deserves a more accu- rate notice. It is distinguished, as may be seen in fig. 134, by a peculiar tympaniform dilatation of the base of the hyoid bone, by which a repercussion of the exhaled air seems to be produced. A great resonance, effected by the elasticity of the parietes of this bony cavity, must be the result of this repercus- sion, by which the terrible howhngs of these animals are produced. Upon the other soft parts of the Cebincs there is nothing very particular to say. I mention only the structure of the stomach in Ateles and Mycetes, in which, according to the ob- servations of Cuvier and of Prince Maximi- lian, there is some tendency to the saccu- lated form of the stomach in the Semnojntheci. This pecuHarity confirms all that I have said before about the analogy between Ateles and Semnopithecus. In the organs of generation the length of the clitoris is worth notice, particularly in Ateles and Cebus. According to the observations of Leuckart * it has an convolutions in the brain of Hapale rosalia and jac- chiis. Recently I. Geoffroy St. Hilaire has showed to the French Academy two brains of Ouistitis, and has in\-ited the members to verify the three state- ments which he published, viz., "I'existence de chaque cote d'un sillon profond transversal entre le lobe cerebral anterieur et le lobe moyen ; celle de quelques sillons Hneaires et superficiels correspondant au trajet des vaisseaux, et I'etat lisse de la presque totahte de la surface des hemispheres." — Comptes Rendus, n. 714, Aout, 1843, p. 280. * F. S. Leuckart, Zoologische Bruchstucke t Stuttgart, 1841, ii. p. 61. p 3 214 QUADRUMANA. OS clitoridis, which grows larger at its anterior extremity. Rudolph i seems to have been misled by it, in his description of a presnmed hermaphroditical monkey. It is very probable that he did not examine an hermaphrodite, but a female Ccbus cajmcinus* Fig. 134. Vertical section of the hyoid hone and larynx of My- cetes seniculus. (^Afttr Sandifort.') About the embyro-genesis of the Ceblncs "Rudolph I published some interesting notices. He observed in the Oidstitis that the ompha- loid vesicle persists till the last period of gestation, and that there are in Hapale^ ^^y- cetes, and Cebus two umbilical veins, which unite near the liver. As an appendix to all these anatomical observations about the CebincB, I join the re- sults of the dissection of Nochthora trivirgata, which I made in the month of Jul y, 1843, in the Zoological Society of London. The sto- mach has the transversely oblong form proper to the monkeys in general, and not the round form of the Slcnops ; consequently the coecal sac is not so ample as in Stcnops. The coecum terminates in a more elongated coecal point than in Stenops. It wants cells, as in the greater part of the American monkeys. In the encephalon the hemispheres are larger in their anterior iobes ; they cover almost the whole cerebellum ; the fossa Sylvii is trans- verse, and very deep ; the mesial lobes are very distinct ; the asymctry between the two hemispheres is not so distinct as in Stenops, by all which characters the brain of the Noch- thora trivirgata approaches to the monkeys, and differs from Stcmups. The laryngeal ap- * Rudolplii, ueber eine seltene Art. des Herma- phroditismus bei einem Alfe (Simia capucina) in Abhandl d. Konigl. Alcad. d. Wissenscli. in Berlin, in J. 1816—1817; Berlin, 1819, 4to. Pliysik. Classe, p. 119. paratus has a great deal of analogy with that of 77um; the thyroid cartilage is large and prominent, and has almost the same form as in jnan. The epiglottis is much developed, particularly at its base. The arytenoid car- tilages are much elevated. The 7'ima glottidis is wide. The tongue differs from the same organ in Stenops, in which it is sustained by a triangular and flat cartilage. In the Noch- thora, on the contrary, it has the general structure of the tongue of the monkeys, being long and narrow, with isolated papillce. The heart has an oblong form. The first ramifications of the arcus aortas are similar to those of man. The right lung is divided into four, the left into two lobes. II. Lemurin^e. Prosimicc. The second large family of Quadrumana is formed by the Lemurince. They have the general aspect of the American monkeys, but their muzzle is lengthened and pointed, and in the hind feet the first toe is the only one armed with a crooked subulated nail, while the other nails are flat. The four thumbs are opposable ; the teeth differ very much in the different genera, but the molars offer in gene- ral the pointed and alternating tubercles pro- per to the Insectivora. 1. First Genus. OtoUcnus Illig. Galago. The teeth of OtoUcnus are as follows, 4 . 1 — 1 , viz. incisors, — : canines, : molars, 4 1—1 ~ — ^=z36. The inferior incisors are very 6—6 ^ narrow and compressed ; they resemble much the teeth of a fine comb, and are entirely united together. The tarsus is very long, by which the hinder extremities acquire a disproportionate size, and produce a jump- ing motion. Their tail is very bushy; their ears large and membranous ; their eyes very large, and announce their nocturnal habits. Africa. Spec. — OtoUcnus Scnegalcnsis, O. 2Iada- gascariensis. 2. Second Genus. Tarsius. Tarsier. T . 4 . 1—1 , 6—6 Incisors, — ; canines, ; molars,- =34 2 1 — 1 '6—6 Has the remarkably long hind legs, the large ears and eyes of the preceding genus ; but the interval between their true molars and their incisors is filled up with short acumi- nated teeth, of which it is difficult to say if they are canine or molar, and the superior middle incisors are very long, and resemble canine teeth. The muzzle is very short. They inhabit the MoUucca islands, and are noc- turnal animals, feeding upon insects. Spec. — Tat'sius spectrum. Third Genus. Stenops Illiger. Loris. Singe paresscux, Fr. Sjwokdier, Dutch. The teeth as in the Lemurince in general, but the external incisors of the upper jaw are very QUADRUMANA. 215 often wanting. The first molar of the lower jaw on each side is so much acuminated and in- curved that it resembles a canine. The muzzle is short and triangular ; the ears small ; large nj'ctalope eyes, close to each other ; no tail, or a short one, and a long narrow tongue. They feed upon insects. Their habits are nocturnal, and their movements very slow. They inhabit Eastern Asia. Spec. — Steiiojjs iardigradus, S. gracilis^ S. javanicus. To these ought to be added the Stenojjs potto Bosnian, coming from the coast of Guinea. It has a short tail and a short index. In a skull of a young Stcnops potto, from the Museum at Leyden (y?g. 135), the distance Fig. 135. Skull of Stenops potto. ( Original, Mus. Leyden.') between the two orbits is much larger than in Steno'ps javanicus, iardigradus and gracilis. It is the narrowest in Ste?iops gracilis, broader in Stenojjs javanicus, still broader in S. Iardi- gradus, and the broadest in ^S*. potto. In S. potto the circular boundary for the orbits is not so distinct as in other species. Fourth Gemis. Lichanotus Illiger. Iiidri. The same form of teeth, but they have only two incisors in the lower jaw. This genus has but one species (L. Indri), distinguished by the want of the tail. Madagascar. The dental formula is : Incisors, - ; canines, ? : molars, 1^=30. '2' '2' '10 Fifth Genus. Semnocebus Lesson. Avahi. The Semnocebus approaches very much to Lichanotus, from which it differs by the exist- ence of a tail, and by the form of its skull. In a skull of the Mus. Leyden {f g. 136 ), Fig. 136. Sliull of tlie Avahi. (^Original, 3Ius. Lei/den.) I observe a depression on the frontal surface, between the two orbits, which part is, on the contrary, convex in Lichanotus. The muzzle is not so much protruded as in Lichanotus^ and more flat on its anterior part, formed by the intermaxillary bones. The teeth are the same in both. Madagascar. Spec. — Semnocebus laniger or Avahi. Sixth Genus. Cheirogaleus. Among the unpublished drawings of Com- merson, Geoffi'oy St. Hilaire discovered re- presentations of certain Lernur-like animals, which he considers as constituting a distinct genus. The characters were at first very in- distinct ; but we are now acquainted with the external aspect, the skull, and the teeth of this genus. The dental formula is : incisors, 2—2 . 1—1 1 6—6 rp. ; canmes, ; molars, =36. The 6 1—1 5—5 superior incisors are situated in two pairs, with a great interval between both. On each side of the upper jaw there is a large canine, with six molars, of which the two first have acuminated crowns, and seem to be spurious molars; the four posterior are tuberculated. In the lower jaw there are six long and narrow prociive incisors, of which the two exterior are the strongest ; a vertical canine on each side ; a spurious molar with acuminated crown, and five true tuberculated molars. In the form and the size of the skull, Cheiro- galeus has some analogy with Lemur, parti- cularly by a pecuhar opening in the zygo- matic bone. The muzzle however is not so prominent, and the interval between the orbits smaller. The form of the skull is in- termediate between Lemur and Stenops. Spec , — Cheirogaleus C omm e r s on 1 1 . Seventh Genus. Lemur. Malci, Fr. Meer-kal, Dutch. Incisors, ^ ; canines,^?— ^ ; molars, ^ - = 36. 4 1 — 1 '6—6 The six inferior incisors are compressed and directed forwards ; of the four superior ver- tical incisors, the two middle are distant from each other; the canine teeth are very acumi- nated ; the molars acuminated and alternating in each jaw. The ear not much developed. The tail long, bushy, and highly ornamented. The muzzle is very prominent, lengthened, and pointed ; for which reason the French call the Makis Singes d museau de renard They feed upon fruits, and inhabit chiefly Mada- gascar. Spec. — Lemur calta, Tj. macaco, L. ruber, L. mongos, L. albifrons, L. nigrifrons, L. rufus, L. albimanus, L. cinercus. The Lemur murimis, Maki nain ought to be separated from the other Lemurs. It seems a transition to OtoUcnus. Eighth Genus. Galcopithecus. Vliegoide-hat, Dutch. This genus has been considered by Cuvier to belong to the Cheiroptera, but Temminck and De Blainville have perfectly well de- p 4) 216 QUADRUMANA. monstrated that it is not a Vespei^tilio but a Lemur, and that it forms in this way a tran- sition from the LeimirincB to the Cheiroptera. The author of the article Cheiroptera in this Cyclopcedia has adopted the same views, and I agree with them, including the Galeo- pithecus in my present paper. The Galeopi- thecus, then, is a Lemur, with the extremities connected by a bat-like membrane, or, in other words, surrounded by a thin skin, which they support as the framework of the umbrella sustains its covering. By this singular struc- ture, the animal while jumping is suspended in the air, yet without the power, as the Bats, of a continued flight. The fingers of the hands are not longer than those of the feet, and pro- vided in both with long and sharp incurvated claws. They dwell upon trees in the Indian Archipelago, and feed upon insects, and, per- haps, little birds. They sleep, as the Bats, suspended by their hind legs, with their head downwards. According to the observations of Waterhouse, their dentition is as follows : 2—2 . 0—0 incisors. false molars, 2—2 2—2 these teeth true molars, 4— 4< :34. The form of 4—4 is very strange. The anterior incisor of each side in the upper jaw is of a small size and compressed form, suddenly dilated above its insertion in the jaw, serrated at the edge, and presenting three or four nearly equal denticulations. The second in- cisor on either side resembles the first false molar in form, and, like that, has two fangs. The first false molar is compressed, of a tri- angular form, and has the anterior and pos- terior edges serrated. The second false molar is less compressed than the first, and divided into two nearly equal, acutely pointed, trian- gular cusps ; the apex of the posterior cusp is directed inwards. The triangular grinding surface of each of the true molars consists of three pointed cusps. The molars of the lower jaw resemble those of the upper, ex- cepting that the position of the three prin- cipal cusps is reverted. The false molars are compressed and resemble, in general, their opponents of the upper jaw\ The tooth, which represents the canine, is comparatively small, compressed, and considerably expanded at the apex, where it is serrated, having five or six denticulations. The incisors are almost horizontal in their position, compressed, nar- row at the base, and suddenly expanded im- mediately above the base ; each incisor is deeply festooned or subdivided by incisions into slender lam'mce. The incisors and false molars of the lower jaw are detached. Spec. — Galcopithecus variegatus. Osteology. — The considerations upon the skeleton of the LemurhicB ought to be con- Fig. 137. Skull of Gakopithecus variegatus. {After Waterhouse.') QUADRUMANA. 217 nected with those upon the Ceb'mcB, in which I said that the form of the bony framework passes gradually and in a descending line into the form of theLemurince, and by those into the form of the smaller Carnivora and Insectivora. The truth of this assertion will be proved by the examination of the skull. In all the skulls of the above-mentioned genera of LemiirincB, the orbits are open posteriorly, and most so in the Galeopithecus {Jig, 137), which we shall take as type, and in which there is a large distance between the orbital process of the frontal and of the zygomatic bone united to- gether in Tarsius, Lichanotus, Stenops, Otolic- nus, and Leviur, and forming there a boun- dary for the open orbit. In all the LemurincB there is a double frontal bone, with two nasal bones, which are universally very long, and protracted to the anterior part of the muzzle, principally in Stenops, in which they form a sort of tube with the inlermaxillar bone. The facial suture of the intermaxillar bone is in general distinct. The lacrymal canal is situ- ated not in the orbit, but on the facial surface of the superior maxillary bone ; in Cheirogaleus {fig. 138) and Lemur ^ there is a regular oval Fig. 138. Skull of the Clieirogaleus Commersonii. ( Original, Mus. Leyden.^ opening, in the zygomatic bone, similar to that, which I described in Lagothrix, Mycetes, and Ateles. In the glenoid cavity of the tem- poral bone there is a vertical ridge to prevent the backward dislocation of the lower jaw. The coronoid process of the lower jaw is very distinct, as in all the animals, in which the orbits are open posteriorly, and the chin is more depressed than in the Monkeys and CeUncB. In the vertebral column the cervical vertebrcB are seven in number. The anterior vertical ridges of the transverse processes, in the pos- terior cervical vertebrae, are more developed than in the Cebince, and extended over a larger number of vertebrae. The spinal process of the epistrophaeus has the quadrangular form, with the posterior cutting edge of the Carnivora, In the dorsal vertebrae, the tendency to the form of the lower orders of Mammalia is still more distinct, firstly in their augmented num- ber, which is in general 13, but increases to 15 or 16 in Stenojjs. The spinal processes offer the opposite direction which is proper to the inferior orders of Mammalia, excepting in Ste- nosis and Lichanotus, in which they are all inclined backwards. The bodies of the dorsal vertebrae are in general all of the same size, and they do not augment, as in the higher order of monkeys of the Old World. In the lumbar vertebrae there is also an augmentation of number, which varies from 6 — 8 or 9. In Lemur the form and direction of the spinal lumbar processes have much analogy with those of the Carnivora^ being incurvated and directed forwards. In Stenops^ Otoiwnus, and Lichanotus, they have a more quadrangular form. The styloid processes are much deve- loped. The transverse processes are strong, quadrangular, and directed forwards, as in the Carnivora. The sacrum has the form of a large quadrangular bone, with sharp and straight edges, united by one, two, or three spurious vertebrae with the iliac bones. The form of the pelvis resembles that of the Car- nivora. The iliac bones have two surfaces, an anterior or internal, slightly convex and narrow, a posterior or external, concave and broad. They unite together in a sharp, an- terior edge, of which the anterior and inferior iliac tuberosity forms the anterior and inferior termination. The horizontal branches of the pubis are very distant, and make the pelvis pretty large. By this disposition and by the inclination of the pelvis, it resembles very much that of the Carnivora, and especially of the Cercoleptes caudivolvulus, which has so many other points of analogy with the Lemu- rincB. The thorax is compressed, but the ribs are not very convex, as in most of the Car- nivora. In the Sternum there is scarcely a manubrium, but its body is separated into as many long and narrow segments or Sternehrcs as there are true ribs. In the scapula, the coracoid process is recurved and directed downwards, as in the Squirrels and other claviculated Mammalia. This is, as I have said before, a distinct manifestation of infe- riority. In the humerus there is, in general, an aperture in the internal condyle for the passage of the brachial artery and the median nerve. The fore-arm has a different disposition in the various genera. In most of them it is composed of the two ordinary bones, the radius and the cubitus, of which the radius is in general curved outwards, and the cu- bitus straight. But in the Galeopithecus, the transition to the form of the Bats appears in the disposition of the ulna, which is imperfect, not prolonged to the carpus, but terminated in a slender filiform extremity, which is united with the radius. In the hand, the quadrumanous type is visible in the thumb, which is separated from the other fingers, even in the Galeopithecus. But in no genus of the Lemurince is the form of the hand so peculiar as in Stenops. Its prin- cipal character consists in the shortness of the index, and in the proportional length of the thumb and of the fourth finger, which is the longest. The carpus is composed of the same number of ossicles as in the monkeys of the Old World ; but as I have proved in another paper*, its connexion with the anti- * W. Yrolik, Rech. d'Aiiat. Comp. sur le Genre Stenops d'llliger, in N. Verliand. d. eerste classe van het Koninkl. Xederl. Instituiit. Amsterdam, D. ix. 1843. 218 QUADRUMANA. brachium is less firm, by which the hand acquires a great deal of mobility, and can be incUned, as I have often observed, not only outwards, but also backwards. With regard to the posterior extremities, the principal deviation is oifered by the Tarsius, in which the fibula is but a slender filiform bone, not extended to the tarsus, but terminating on the third inferior part of the tibia, with which it is united. Consequently the tarsal articu- lation is only united with the tibia. A yet more striking peculiarity is exhibited in Tarsius and Otolicnus by the tarsus, in which the calcaneum and the scaphoid bone are two long styliform bones, contributing in that way to produce the enormous length of the posterior extremities. In the Stcnops there is not so great a deviation from the ordinary form to be observed ; but it is, how- ever, of some interest, that the two Malleoli are very small, and that the astragalus has an oblique direction inwards. The results of this disposition, as I have proved more minutely in the said paper, are a greater mobility of the foot, a direction upwards of its internal edge, and a great interval between the thumb and the other digits. Myology. — I can only mention the mus- cles of the Stenops, having had no opportunity to dissect the other genera of Lemurincs. The sterno-mastoideus has a distinct clavicular fascicle, the existence of which is very interest- ing, while it is not found in some monkeys, nor in any of the mammalia which have no cla- vicles. In the M. d/gastricus there is but an in- dication of intermediate tendon ; consequently the muscle is simplified, and passes into the form it has in the Carnivora, in which it is composed of a single fascicle. Another pecu- liarity in the muscular system of the Stenops is the existence of the omo-hyo'idcus^ which is wanting in many large Mammalia, but exists in the monkeys, and as my dissection has proved in the Dasyunis^ the Ursus arctos, the Pteroj)us, and the Opossum. This muscle is also one of the links connecting the genus Stcnops with the Quadrumana on one, and with the Carnivora on the other side. The latissimus dorsi gives, in the same manner as in so many other climbing animals, a pro- longation to the internal condyle of the hu- merus. The pectoralis viagnus has the length and the strong disposition of fibres, proper to all the quadrupeds. As in them, the clavi- cular fascicle is not much developed. The disposition of the bicej^s and hrachialis interjius is interesting, because it proves that the genus Stenopsy and probably the other Lemurincs, form a transition from the Quadrumana to the Carnivora insectivora. In the same manner as in these, the biceps consists of but one fascicle, which arises from the superior edge of the articular cavity of the scapula, and is inserted into the radius, and the brachialis interims pos- sesses but an external fascicle, which passes to the antibrachium, behind and under the biceps. It is very remarkable, that notwith- standing the want of the internal fascicle of the biceps, there is a coraco-brachialis. It is prolonged downwards to the internal condyle of the humerus ; between it and the internal fascicle of the triceps passes the cu- bital portion of the vascular' plexus. This is an exception to the rule, that the existence of a coraco-brachialis is connected with the ex- istence of an internal fascicle of the bicejis, and an additional {)roof that the genus Stenops forms a transition from the Quadrumana to the Carnivora. In the antibrachium the prona^ tores and sujnnatores are very strong. The Jlexores are the radialis and ulnaris internus, with the palmaris longus. The extensores are the radialis externus longus et brevis, with the uhiaris externus and the extensores of the fingers. For the flexion of the fingers, there is a rudimental flexor superficialis^ which is wanting in the Carnivora, and which exists, on the contrary, in the Quadrumana. Instead of the abductor magnus and extensor brevis poinds there is but one muscle, formed by the union of both these muscles. I have shown already that this tendency to simplify is yet observed in the Orang-cetan and in the Alandrill, and more distinctly in the hiui. Besides this the thumb of the Stenojys pos- sesses a flexor brevis, an abductor brevis, and an adductor j^ollicis. In the posterior extremities we observe, first, a very long and very strong psoas, composed of two portions, of which the in- ternal is the strongest. They are united to the iliacus internus and attached to the small trochanter. Thesartorius has an obhque di- rection, and is attached to the internal edge of the tibia. The gracilis is broad and attached lower to the tibia. The rectus femoris, the cruralis, vastus externus and internus have their usual disposition. There is no jyectijueus, but there are three adductores. It is very re- markable that the adductor magnus forms no aponeurotic canal for the passage of the plexi- form crural artery, but that this passes only on the superior margin of the adductor magnus, and penetrates in this manner into the popli- teal cavity. I have stated the same disposi- tion in the Bradj/jms didactylus, in which, and also in the Stenops, this deviation seems to be connected with the peculiar ramification pro- per to the vessels of the extremities, by which they are more preserved from compression, than in the animals, in which the crural artery forms but a single tube. On the posterior surface of the thigh there are a semi-tendinosus, semi- membranosus and biceps. The semi-tendinosus is united to the gracilis. The semi-membrano- sus has its own insertion. They descend very low and surround the gastrocnemius. The biceps terminates on the superior part of the tibia with a large muscular fascicle. Theglu- tcBus maximum has a large insertion on the thigh, and is inserted very much downwards. On the anterior crural surface there are a tibialis anticus, an extensor magnus and brevis digitorum jjedis, and extensor brevis hallucis, which has a very oblique direction, and d^per- oncEus magnus and brevis. As regards the flexores, I have only to mention the union of the flexor magnus hallucis with the flexor mag- QUADRUMANA. 219 fius quahior digitoriim pedis, which are united in the same manner as in the monkeys. They both give tendons to the toes, of which each receives consequently two tendons. The plantar surface of the tendon of the flexor magnus qua- tuor digitorum give off four lumbricai muscles. Instead of a flexor hrcvis there are but small tendons, which bifurcate for the passage of the tendons of the flexor magnus hallucis, and Hexor magnus quatuor digitorum pedis. The tibialis j)osticus is very strong. The small mus- cles of the posterior thumb or great toe are the abductor, the flexor brevis, and the adduc- tor. Their strength is connected with the mobility and with the removed position of the posterior thumb, giving a great deal of agility to the Slenojjs in his climbing motions. lutions,the shallow anfractuosities, the scarcely indicated fossa Sylvii, the not prominent Varolii^ the very thick cerebral peduncles (crura cerebri^, the want of corpora candicantia, the short corpus callosuvi. In all these points the brain of the Stenops is inferior to that of the monkeys, from which Stenops differs also by more imperfect intellectual faculties. For the organs of sense, I mention princi- pally the interesting existence in the Stenops, of the tapetum lucidum in the eye, by which the animal acquires the faculty of reflection of the light, improperly called phosphorescence of the eyes. In general the sensibility of the eye to light is very exquisite. Therefore most LemurincB are nocturnal, and see very well in almost profound obscurity, as is proved by the observations of F. Cuvier, in the Lemur muriniis. The ears of Stenops are very large ; the concha deep, the tragus imd anlitragus ele- vated, and instead of anthelix there are two prominent and almost parallel cartilaginous plates. The same development of the ear is observed in the genus Otolicnus. This great development in a nyctalope animal is an inter- esting fact, principally by comparison with the Cheiroptera^ in which the same disposition occurs. The tongue of the Stenops offers a strange structure in the existence of a cartila- ginous plate, by which it is supported, and the anterior margin of which is denticulated. Angeiology. — I only know some peculiari- ties about the heart and the vessels of the Stenops. It has a rounded and pla.ne form ; Neurology. — The encephalon of the Lemu- rincs is only known by the dissection of the Lemur mongos and of the Stenops javanicus and tardigradus. Science is indebted for the first to TiEDEMANN, and for the two last to SciiR(EDER VAN DER KoLK and to mysclf. The encephalon of Lemur mongos seems superior to that of Stenops, by the larger development of the hemispheres, the greater breadth of the anterior lobes, the more numerous convolu- tions and deeper anfractuosities, but otherwise they offer the same type. I have minutely desci'ibed the brain of the Stenops tardigradus in my paper on this animal, and I mentioned there the small development and the asyme- try of the hemispheres (flg. 139), the triangu- lar form of the anterior lobes, the few convo- the right ventricule is scarcely longer than the left, and terminates in a rounded point. The right auricle is much larger than the left. The distribution of the trunks coming from the arcus ao7-tcE is as in the plurality of Mannna- lia, viz. three trunks coming from the a. inno- minata, and a separate left subclavian artery. But the most interesting is the ulterior distri- bution of the arterial and venous vessels in the extremities. Sir A. Carlisle was the first to show, that they form plexuous ramifications, consisting of a large number of narrow cylin- drical vessels anastomosing together. Eighteen years ago, I repeated the observations of this excellent anatomist on various animals, and confirmed their veracity against the objections of Oken and Gaibiard ; and recently I had again the opportunity to show, that these ra- mifications exist in three species of Stenops ; that in the same manner as has been proved for the Bradi/pi, by Sciirceder van der Kolk and Otto, they consist not only of arteries, but also of veins ; and that, by dividing in branches, these ramifications become smaller and smaller, and composed of a less number of vessels (flg. 140). Splanchnology. — The stomach hasin-S/e-- nojjs a rounded, almost globular form, in which the cardiais near to the pylorus, and the coecal sac much developed. Consequently the con- cave margin of the stomach is small, the con- vex, on the contrary, large ; with these is connected the elongated spleen. This dispo- sition of the stomach, and especially the 220 QUADRUMANA. approximation of the cardia and pylorus, seem proper to all the Leniumice, and already pre- Fig. 140. Superior limb of Stenops tardigradus. (^After W. Vrolik.^ sents its first appearance in some Cehida:. The coecum terminates in an elongated, conic point, which ought not to be confounded with the vermiform appendix of the ccecuro in man and in the apes. The coecum is very large, and thecolonhas also a great extension. The colon is in general larger in the Lemurince than in the SimicB. It is said by Cuvier to want cells. In Lemur murinus it is short and ample. Duver- NOY and ScHR(EDER VAN DER KoLK describe alternating constrictions and expansions in the intestinal canal of Slenojis, which, how- ever, I did not find in the three Loris 1 had the opportunity of dissecting. About the organs of voice and respiration I have, first, to mention the complete osseous disposition of the laryngeal cartilages ; se- condly, their small development ; and thirdly, the bifurcated disposition of the epiglottic. All these points are proofs of imperfection, by which may also be explained the total want of voice in Stenoj:>s. The hyoid bone is different from the hyoid bone in the monkeys, and ap- proaches to that of the inferior ManimaUa. Its body is a transverse arch, slender, and united at the two extremities with the two pairs of horns. The anterior horns aFe composed of two distinct bones, of which the first is broad and flat, the second long and slender. The thyroid or posterior horns are broad and flat, and melting away with the basis of the bone, while the anterior have a free articulation. The hyoid with its horns has the form of a transversely inclined X, viz. X. In the organs of generation, the narrowness and convoluted disposition of the Fallopian tubes, the length of the vagina, and especially Fig. 141. Female external organs of generation of Stenop tardigradus. (^After W. Vrolik.) RADIAL AND ULNAR ARTERIES. 221 the perforated condition of the clitoris, merit our attention. The clitoris is very prominent, and through it passes the urethra. Conse- quently it has the structure of a penis, of which it is the representative in the female As appendix to my paper on the Quadru- mana I think it necessary to mention the Cheiromys 'psylodactylus or Aye- Aye of Mada- gascar. This singular animal seems interme- diate between the Lemurina: and Rodentia. It has the teeth of the last, but all the other characters of the first. De Blainville has elucidated them in a learned paper, published a second time in his Osteographie, and he has proved, indeed, that by the general form of the skull, by the situation of the foramen occi- pitale magnum^ and of the lacrymal opening, by the existence of an intermediate bone in the carpus, by the length of the calcaneum and scaphoid bone, the Cheiromys is indeed a Le- murine animal. But we want a more per- fect acquaintance with its organization and with the form and number of its teeth in early age, before it will be possible to determine exactly, where this very rare animal ought to be placed. To complete my anatomical description of the Quadrumana it will be necessary to men- tion the fossil specimens discovered recently in Europe, India, and Brazil. The European specimen consists in a lower jaw, discovered near Auch in a soil of tertiary formation. It seems to be of a Cercopithecus. The Indian specimen was found in tertiary formation of the mountainous district of the Himmalaya. It is a fragment of a lower jaw, having some analogy with the lower jaw of the Entellus. The third specimen is American, and consists in different bones of fossil Quadrumana, which seem to be of a Cebiis much larger than the modern species. Bibliography. — Maximilian, Pr. zu Wied., Beitr, z. Naturgeschichte von Brasilien, Weimar, 1826, B. 2. R. P. Lesson, Spec, des Mammiferes bi- manes et quadnimanes, Paris, 1840. J. Geoffroy St. Hilaire, Desc. des Mammiferes noiiveaux ou im- parfaitement connus de la Collection du Museum d'Histoire naturelle, in Arch, du Musee d'Histoire naturelle, tom. ii. 4 Liv., Paris, 1841, p. 485. Tem- minck, Monographies de Mammal ogie, Leyde, 1835, tom. 2. 12e. Monographic sur le Genre Singe, Simia Linn. Blainville, Osteographie, ou Description ico- nographique comparee du Squelette et du Systfeme dentaire des Cinq Classes d'Animaux vertebres recents et fossiles. Ogilhy, The Menageries, in Libr. of Entert. Knowledge, London, 1838, vol. i. Berichte von der koniglichen anatomischen Anstalt zu Konigsberg : Jer Bericht von Heinrich Rathke, mit einem Beitrage zur vergleichenden Anatomie der Alfen, von Ernst Burdach, Konigsberg, 1838. J. A. Wagner, Beitr. zur Kenntniss der warmblutige Wirbelthiere Amerika's, in Abhandl. d. mathem. physik. Class, d. konigl. bayer. Akad. d. Wissensch., Miinchen, 1837, 2 B. p. 419. Natimrkundige Ver- handelingen van P. Camper over den Orang-outang en eenige andere Aapsoorten, Amsterdam, 1782. R. Owen, On the Osteology of the Chimpanzee and Orang-utan : Trans, of the Zool. Soc. of London, vol. i. p. 343, London, 1835. G. Sandifort, Ont- leerkundige Beschryving van een volwassen Orang- oetan (^Simia Satt/rus) in Yerhandelingen over de Natuurlyke Geschiedenis der Nederlandsclic over- seesche Bezittingen, Leiden, 1840. Herman Schlegel en Sal. 3Iuller Bydragen tot de Natuurlyke Historie van den Orang-octan in the same Memoirs. E. Tyson, Orang-outang, sive Homo sylvestris, or the Anatomy of a Pygmie compared Avith that of a Monkey, an Ape, and a Man, London, 1699. T. S. Traill, Observ. on the Anatomy of the Orang-outang in Mem. of the Wernerian Natural History Society, vol. iii., Edinb. 1841, p. 1. C. F. Heusinger, Vier Abbildungen des Schcdels der Simia Satyrus von verschiedeneu Alter., Marburg, 1838. A. Vosmaer, Beschryving van de zoo zeldzame als zonder- linge Aapsoort, genannd Orang-outang van het Eiland Borneo, Amsterdam, 1778. D. L. Osamp, Naauwkeurige Beschryving van den grooten en kleinen Orang-outang, Amsterdam, 1803. W. Vrolik, Reclierches d'Anatomie comparee sur le Chimpans^, Amsterdam, 1841. F. Tiedemann, Icones Cerebri Simiarum et quorundam Animalium rario- rum, Heidelberg, 1821. F. Tiedemann, Hirn des Orang-outang^ s mit dem des Menschen verglichen in Zeitschrift f. die Physiologie, Darmstadt, 1827 ; 2 B. p. 17. a A. Rudolphi, Ueb. d. Embrj^o d. AfFen u. einige andere Saugethiere, Berlin, 1828. T. S. Leuckart, Ueb. die Bildung d. Geslechtsor- gane insbesondere der aiisseren einiger Affen in Zoologische Bruchstucke; Stuttgart, 1841, ii. p. 37. A. W. Otto, Ueb. eine neue Aftenart den Cercopithecus leucoprymnus in Nov. Act. C. L. C. nat. Curios, vol. xii. p. 2. R. Owen, On the sacculated Form of stomach as it exists in the Genus Semno- pithecus. Trans. Zool. Soc. vol. i. p. 65. G. Fischer, Anat. d. Maki, Frankfort am Main, 1804. G. R. Waterhouse, on the Genus Galeopithecus ; Zool. Trans, vol. ii. p. 4. J. L. C. Schroeder van der Kolk, Bydrage tot de Anatomie van den Stenops Kukang in Tydschr. voor Nat. Geschiedenis en Physiologie, D. 8. pi. 277. W. Vrolik, Rech. d'Anatomie comparee sur le genre Stenops in N. Verhand. der le Klasse koninkl. nederl. Inst. D. 10. Amsterdam, Oct. 1843. To this bibliography ought yet to be added H. Burmeister, Beitrage zur naheren Kemitniss der Gattung Tarsius, Berlin, 1846. I regret that this very valuable work was not published when I wrote my article in 1843. (IV. Vrolik.') RADIAL AND ULNAR ARTERIES. (Arteres radiale et idnaire — Speichcnpidsader und Ellenbogenpulsader.) — The nomenclature of the different branches of the systemic cir- culation is based upon two principles. Ac- cording to one of these, the distinction of appellation is grounded upon the tubes them- selves ; their different ramifications being designated by as many names, which usually more or less connote the ultimate destination of the vital fluid they contain. Where this method fails, another remains, which, though essentially arbitrary, is yet of the highest im- portance : a method which, in order to their stricter contemplation by the anatomist, and their more accurate recognition by the sur- geon, isolates different lengths of one and the same tube, according to changes in its position and relations with respect to neigh- bouring parts. The radial and ulnar arteries, whose anato- my is here to be considered, are included in the first of these categories ; being the branches which result from the bifurcation of the artery for the upper extremity. Com- mencing in their ordinary distribution, oppo- site and anterior to the elbow joint, they 222 RADIAL AND ULNAR ARTERIES. continue along the whole front of the forearm, each m tolerably close proximity to the bone whose name it bears.* The ulnar, by simply continuing this course, arrives at the hand, but the radial previously turns round the outer side of the wrist to reach the first meta- carpal interval, which it perforates. Each now takes a curved course in the palm ; a curve, whose convexity is forwards, whose situation — superficial or deep — follows that of the artery with which it is more imme- diately continuous, and which, completed by a branch or branches from its fellow, forms that from the ulnar the superficial, that from the radial the deep, palmar arch. Since either of these arches has a share from both vessels, it might at first sight be supposed that we are here presented with a rare peculiarity in the uninterrupted artery traceable from the radial through its palmar arch to the ulnar, or vice versa. But their apparent mutual continuity offers no difficulty to the exact nominal definition of each vessel and, obviously, the anastomosis differs from that common to all arteries only in degree : viz., in the greater freedom of communication which is the consequence of the larger size of the branches effecting it. The brachial artery, inclining somewhat forwards in the lower part of its course, so as to gain the angle of flexion of the limb, lies at its termination on the brachialis anticus, where this muscle becoming tendinous, covers the coronoid process of the ulna previously to its insertion into the apex of the rough non- articular surface of this prominence. Here it divides. The radial artery. Its relations. — The radial artery begins as the outer of the two divaricating branches, and ends as the deep palmar arch : in this course it offers three chief variations of regional anatomy, which will require a separate consideration. The first of these divisions may be regarded as terminating at the lower border of the radius, the second at the superior extremity of the first metacarpal space in the back of the hand, and the third at the point where, after break- ing up into the radialis indicis, magna poUicis, and palmaris profunda vessels, the latter of these, lying deeply in the inner side of the palm, unites with the communicating branch from the ulnar artery. {a.) In the forearm, the artery is directed at first downwards and externally, but afterwards more vertically, so as to exhibit a slight curve, whose convexity is upwards and outwards. It thus corresponds for a very short distance — say one third of an inch — to the coronoid process of the ulna, and lies on the brachialis anticus ; but in the whole of the remainder of its length it is related to the anterior sur- face of the radius, and is situated on the muscles which immediately cover it. Crossing the inner surface of the tendon of the biceps * It will be borne in mind, that here, as in all descriptions of this part, the forearm is supposed to be supine, and hanging vertically by the side of the trunk. as this sinks to its insertion, it by turns comes into contact with the cellular tissue on the supinator radii brevis, and lies upon the pronator radii teres, as this passes outwards to its insertion ; then for a short distance the radial origin of the flexor sublimis digitorum sustains it, and next the flexor longus pollicis; by the passage of whose muscular fibres in- wards to their tendon, it is left opposed to the pronator quadratus, but scarcely touching it from the depth at which this muscle is placed. To its outer side is the tendon of the biceps, and, at first distantly, afterwards more closely, the supinator radii longus, which maintains the relation throughout the remain- der of this portion of tlie vessel : in this situation is also found the musculo-spiral nerve, which descends under cover of the inner border of the muscle, and passes away from the lower part of the artery towards the back of the wrist. To its inner side are suc- sessively, the pronator radii teres in about the upper half of the region, in the lower, the tendon of the flexor carpi radialis ; and be- neath this for a very short distance, that of the flexor longus pollicis. The coverings of the artery are merely the integuments and fascia of the forearm, so that in the whole of its length it is comparatively superficial : and the ordinary cellular tissue surrounds the vessel, while two venae comites accompany its course. It may considerably facilitate finding the artery in the living subject, to bear in mind the superficial indices of its course : and from what has been already stated it may be gather- ed, that in the upper half of this region the vessel is situated in a triangular hollow, whose base is the brachialis anticus in the lower part of the arm, whose outer side is the su- j)inator longus, and whose inner side is the pronator teres. In the lower portion it oc- cu[)ies a linear and comparatively shallow de- pression, between two tendons whose margins the fingers readily recognise through the skin, viz. that of the supinator longus externally, the flexor carpi radialis internally. A line, therefore, from the inner border of the biceps tendon, to the inferior apex of the triangle, indicates with tolerable accuracy the first subdivision of its course ; while another from this point, parallel and equidistant to the two tendons above named, marks it in the remain- der of the forearm. (b.) In the wrist. — This part of the artery is considerably shorter than the preceding, being scarcely one fifth of its length : its di- rection is downwards and outwards from the front of the forearm to the back and lower part of the wrist. In this course, the vessel lies on the external lateral ligament of the wrist joint, and at its termination on the pos- terior ligament of the same articulation ; and corresponds to the scaphoid and trapezium bones which are beneath these. It is covered by skin and fascia, and at first situated at some distance from the surface, becomes to- wards its termination considerably more su- perficial. In its course it is crossed obliquely RADIAL AND ULNAR ARTERIES. 223 by three tendons: in the first instance by two of these placed closely side by side, the extensores ossis metacarpi and primi internodii pollicis ; but by the third, the extensor se- cundi internodii, only just before the artery enters the palm : so that between these two crossings, the vessel runs obliquely downward in the bottom of a groove, which is bounded on each side by these tendons, and whose depth is greatly increased by the action of the muscles with which they are continuous. It finally leaves the back of the hand, by passing between the processes of origin of the abduc- tor indicis. (c.) Inthe'pahn. — The vessel having per- forated the metacarpal space, is situated very deeply in the palm of the hand, beneath the flexor brevis pollicis and the different struc- tures superficial to this muscle ; namely, the tendons of the flexores sublimis and profundus digitorum, with the lumbricales muscles, the branches of the median nerve, and, above these, the palmar fascia and integuments. Immediately giving off its magna pollicis and radialis indicis branches, it now crosses the palm as the deep irnhnar arch, or " palraaris profunda," which, slightly convex forwards, lies on the proximal extremities of the meta- carpal bones, and on the interossei muscles between them ; being directed at right angles to them towards the inner side of the hand, and joined in the fourth metacarpal space by the communicating branch of the ulnar, which completes the arterial circle. This latter part is of course uncovered by flexor brevis pol- licis, and, just at its junction with the com- municans ulnae, it might almost be considered as covered by the flexor brevis minimi digiti. Branches of the radial artery. — Amid very numerous ramifications, the following are those whose constancy and size require a separate mention. (L) Arteria radialis rectirrens. — This large branch is given oft' from the outer side of the radial trunk almost immediately upon its origin from the brachial artery, and whilst it is contained in the triangular hollow before referred to. It passes at first downwards, then outwards, and finally upwards ; lying on the supinator brevis and brachialis anticus successively ; and then occupying the groove between the biceps and supinator radii longus muscles, but overlapped by the latter, it ter- minates in the arm by anastomosing with the superior profunda, which descends to meet it after passing beneath the outer head of the triceps. It has thus a curved course, the convexity of which is directed downwards towards the wrist. Its branches are very numerous, and chiefly supply the muscles with which it is in contact, inosculating with the vessels which they derive from other sources, and with the superior profunda as aforesaid. (2.) Arteria siiperficialis voIcb, which usually comes oft' from the artery just as it leaves the lower border of the radius to turn around the wrist; and, directed almost vertically down- wards, proceeds over the annular ligament and immediately beneath the integuments, until it arrives at the muscles of the thenar eminence ; amongst or upon which it passes, crossing them at an oblique angle, to join the termination of the palmar artery, or, in other words, to complete the superficial palmar arch. Liable to very considerable though un- important deviations in its exact position, perhaps one of the most constant is that where the abductor pollicis lies over the ves- sel, itself placed upon the flexor brevis and opponens muscles. Its varieties in point of size are chiefly connected with the relative proportions of the other arteries, and are de- ferred to them ; but it is usually a very small branch, and, quite as frequently as not, ends in these muscles without any direct junction with the superficial palmar arch. (3.) Arteria anterior carpi radialis. — This is ordinarily a minute branch which comes oft' from the radial, either very close to the pre- ceding, or a little above it. It runs directly inwards in contact with the anterior ligament of the wrist joint, or on the radius at a level just above this ; to join with a similar branch from the ulnar on the opposite side of the wrist, and with the termmations of the an- terior interosseous artery. It supplies the carpal bones and the articulation. (4.) The arteria dorsalis cmpi radialis, or posterior carpal branch, is considerably larger than the preceding, and is given oft" from the radial at a lower level, generally while the artery lies in the deep groove formed by the tendons of the extensors of the thumb. Its course is, like that of the anterior carpal, di- rectly inwards beneath the tendons of the diff'erent fingers; and like it, at about the middle of the wrist, it terminates by uniting with a similar branch from the ulnar artery, and with the terminal ramifications of the in- terosseous vessels. Its size and arched shape are usually much more distinct than those of the anterior carpal vessels. Other small branches are given off' from the radial immediately previous to its enterino- the palm. Thus an arteria dorsalis jwllicis is usually present, and divides, after a short course, into a branch for each side of the thumb ; and there generally exists a similar twig for the radial side of the index finger, either as a separate branch from the radial artery, or from the ulnar division of the bi- furcation just mentioned. A larger branch runs along the interosseous muscle in the second metacarpal space, to divide at its an- terior extremity into branches for the opposed sides of the index and middle fingers. The vessels occupying the third and fomuh spaces, with the same ultimate distribution, rarely arise from the radial ; more usually they come from the posterior carpal arch, and sometimes from the previous metacarpal vessel, or from a similar ulnar branch lying in the fourth space. All these metacarpal branches unite, at the superior extremity of the interosseous space, with the deep arch by means of its posterior perforating branches ; and at its inferior termination, with the digital branches 224 RADIAL AND ULNAR ARTERIES. from the more superficial arch of the ulnar vessel. Their distribution to the fingers cor- responds to that of the arteria dorsahs polli- cis. The arteria magna seu princej)s poUicis is the first branch given off from the radial in the palm, and, as its name intimates, it is usually of considerable size. From the point of its origin it runs downwards beneath the flexor brevis pollicis and tendon of the flexor longus, lying on the metacarpal bone of the thumb, until near the metacarpo-phalangeal joint ; where it divides into two branches, one of which occupies each border of the phalanges, and joins that opposite in the ordinary manner beneath the sentient cushion which forms the extremity of the thumb. The arteria radialis indicis — also given off" beneath the flexor brevis polHcis, runs yet more vertically downwards than the pre- ceding, beneath that muscle and the adductor pollicis, and on the abductor indicis or first dorsal interosseous muscle, to become super- ficial at their lower borders. Here it gives off" a tolerably large communicating branch to the superficial palmar arch of the ulnar artery, and from this point it passes along the radial side of the second metacarpal bone and index finger to its extremity, having a distribution in all respects like that of the digital branches of the palmar arch ; its description is deferred to them. From the arch itself are given off" few branches of any size. Those which proceed downwards, lying on the palmar interossei, are three in number, one for each space, and anteriorly they end by inosculating with the digital branches from the ulnar, like the small twigs already referred to as occupying the same interosseous position on the dorsum of the hand. They have been named " ante- rior interosseous " branches. The remaining branches of the radial are the j^osterior per- forating, three twigs which perforate the supe- rior extremity of the same metacarpal spaces, to anastomose on the back of the hand with the posterior carpal and metacarpal branches. The ulnar artery. — The remaining terminal branch of the brachial is usually much larger than the preceding, with which it is also contrasted by the more linear direction of its course, and by its situation in the different regions through which it passes ; since it oc- cupies the front of the limb from its com- mencement to its termination, and is placed less superficially in the forearm than in the hand. Its relations in the forearm. — In this part of its course its direction is nearly straight, but with a slight convexity inwards, and it corresponds to the ulna in its whole length. At first lying on the brachialis anticus, by passing downwards and rather inwards, it next comes into contact with the flexor pro- fundus digitorum which covers the bone ; and it continues to lie on it to near the annular ligament. Superficial to the vessel are the skin and fascia of the forearm, together with the first layer of the muscles which oc- cupy this situation, or the flexors which pro- ceed from the inner condyle ; viz., the pronator radii teres, flexor carpi radialis, palmaris lon- gus, and flexor carpi ulnaris, successively. It is overlapped by the outer head and border of the latter muscle during about two-thirds of the forearm, being only uncovered where it becomes tendinous ; in this lower part the artery lies external to this tendon, situated between it and the two inner tendons of the flexor sublimis ; structures which would form a very easy guide to its locality during life. Although thus uncovered, the artery is by no means so superficial as was the case with the radial in the same stage ; having in front of it fasciae of great strength, and being placed in a deep depression, from the coming forward of the tendon of the ulnar flexor to its in- sertion in the pisiform bone. The median nerve, which lay to its inner side on the brachialis anticus, crosses the ulnar artery very soon after the origin of the latter, the point of decussation exactly cor- responding to the coronoid origin of the pro- nator radii teres, which shp of muscle lying over the vessel, separates the two structures. The ulnar nerve at its inner side above, where it enters the forearm between the condyle and olecranon, is in close contact with it in the lower half of this region, placed somewhat superficially and to its inner side. The or- dinary venae comites accompany the vessel. In the hand. — In this latter part of its course the artery passes over the annular ligament of the wrist, internal both to the pisiform bone and the muscles of the hypothenar eminence; and next, as the superficial palmar arch, it passes transversely through this part of the hand, crossing superficially to the flexor ten- dons and the branches of the median nerve, until it arrives at the point to which we conducted the superficiaUs volae, and the communicating branch sent upwards from the radialis indicis ; a point nearly at the inner border of the prominent ball of the thumb. Though placed above the tendons and nerves the artery, however, is far from subcutaneous in any part of its progress ; for while on the annular ligament, fibres from the insertion of the flexor carpi ulnaris into the pisiform bone pass outwards over its surface to join that structure external to the vessel lying on it ; a little further downwards, the palmaris brevis, where present, is also directed inwards in front of it ; and during the remainder of its length, the strong palmar fascia effectually shields it from immediate pressure. The ver- tical part of the vessel is accompanied by the ulnar nerve, which maintains the relation it had in the lower part of the forearm, and, inferiorly, divides into its digital branches. The arch, like that of the radial artery, pre- viously described, is convex downwards, con- cave upwards; but it is obvious that its situation is considerably inferior to it, as well as much more superficial. A transverse line across either the middle of the hand or the centre of the metacarpus would tolerably indicate its position, or one continued across RADIAL AND ULNAR ARTERIES. 225 the palm from the forcibly extended thimib might be taken as a more accurate guide to this part of the vessel. Branches of the ulnar artery. — The first branches of the vessel are two, which usually come off by a common trunk, but are nearly as often separate at their origin. They are called the artericc recurrentes ulnares anterior ct posterior, being so named from their taking a recurved course upwards into the arm ; the former in the front of the internal condyle of the humerus, and the latter between it and the olecranon process of the ulna. The an- terior recurrent passes upwards from beneath the flexor muscles which cover the artery where it rises, lying on the brachialis anticus, and corresponding to the elbow joint which it partially supplies ; its superior termination inoscidates with the lowest or anastomotic branch of the brachial. The posterior re- current, having at first similar relations, passes more inwards so as to reach the above in- terval, being situated beneath the flexor carpi ulnaris, and meeting the ulnar nerve de- scending from the arm between the two heads of this muscle. Here it breaks up, anasto- mosing freely with the inferior profunda which has hitherto accompanied the nerve, uniting also by small branches with twigs sent down- wards from the superior profunda in the substance of the triceps, and giving many branches to the articulation and the neigh- bouring muscles. The next considerable branch is the arteria interossea, which diverges from the trunk of the vessel a little below the coronoid pro- cess, and whilst it is covered by the flexor muscles. Directed downwards from its origin, after a course of about an inch in length, it reaches the interosseous mem- brane in the upper part of the interval between the flexor longus pollicis and the flexor profundus digitoruin, and here it bi- furcates into two branches. One of these, the anterior interosseous, continues on the front of this membrane, lying deeply in the interval between the two muscles and con- cealed by them, until, arriving at the pro- nator quadratus which lies transversely across the lower extremities of the radius and ulna, it passes under this muscle. At its inferior border it reappears, though much diminished in size, and now situated on the anterior ligament of the wrist, it divides into many small branches, which supply the articulation and anastomose with the anterior carpal twigs from the radial and ulnar vessels. In this course, the branch now described supplies the muscle on each side of it, and usually it gives off one or two small branches which perforate the interosseous membrane beneath it in their passage backwards to the posterior region of the forearm. One of these, by far the largest and the most constant, is fre- quently named as " the posterior branch of the anterior interosseous;" and it escapes to the back of the forearm, through an aper- ture which exists in the interosseous mem- brane, near its inferior border, and about an VOL, IV. inch and a half above the radio-ulnar articu- lation. The posterior interosseous, the remaining division of the artery, leaves the front of the limb by passing between the radius and ulna above the superior border of the interosseous membrane, and next becomes visible in the back of the forearm, between the inferior border of the supinator brevis and the ex- tensor ossis metacar[)i pollicis. In the re- mainder of its extent it lies on the muscles which arise from the posterior surface of this membrane, and beneath the more superficial layer of extensors and supinators, until it arrives at the wrisr. Here, lying on the pos- terior ligament of the joint, it breaks up into its terminal ramifications, which inosculate freel}' with the posterior carpal arteries of the radial and ulnar, and with the perforating branch of the anterior interosseous division. While this vessel is passing between the two bones above the ligament, it gives off the recurrent interosseous branch, which, usually of considerable size, perforates the lower part of the supinator radii brevis to reach the back of the forearm. Subsequently it is directed upwards, lying on this muscle, and beneath the anconeus, until it attains the lower part of the arm, where it terminates by anastomosing with a large branch or branches which proceed from the superior profunda, as it turns round the humerus, and in the sub- stance of the outer head of the triceps. It supplies the muscles between which it is situated, and sends a branch to the articula- tion of the elbow-joint. iToT^^^"'"^ A very constant branch, thoughr usually ortly of small size, is the twig from the ulnar artery which accompanies the median nerve, con- tinuing along it through the forearm until gradually lost from increasing minuteness. It is the basis of an important variety which will be mentioned hereafter. Low down in the forearm, the ulnar arter}' gives off a branch which runs along the ulnar side of the metacarpus, and supplies this side of the little finger with a dorsal twig. Ac- companied by a branch of the ulnar nerve, it turns backwards from the vessel just above the inferior extremity of the ulna, beneath the flexor carpi ulnaris tendon ; and reaching the inner side of the wrist, continues in a direct line to its termination. It anastomoses with the posterior carpal arch, and, on the metacarpus, with the palmar arch of the ulnar artery. The remaining branches of the ulnar in the forearm are two, the arteria: carpi idnarcs anterior et posterior, which occupy a position closely resembling that of the similar branches from the radial artery on the opposite side of the limb. Each runs transversely outwards on its respective surface of the wrist joint, and unites with the radial branch, and from this union, (which, in the ca«;e of the posterior vessels, is a " carpal arch " in size and re- gularity of arrangement) branches perforate the ligaments to supply the articulations and bones of the caq)us. In addition to the 226 RADIAL AND ULNAR ARTERIES. opposite vessel, the anterior inosculates with the termination of the anterior interosseous and with small branches sent upwards from the superficial and deep palmar arches: while the arch formed by the posterior joins the posterior interosseous, and the dorsal branch of the anterior interosseous : and gives off a small branch which occupies each of the two ulnar metacarpal spaces on the back of the hand. The communicant ulnce is a branch of large size, which passes away from the posterior surface of the ulnar vessel at about the lower border of the annular ligament, and disappears by sinking between the abductor and opponens minimi dii:iti, to join, deeply in the palm, with the ulnar extremity of the palmaris profunda or palmar arch of the radial, to which it usually approximates in size. It gives small branches to the muscles while passing between them. In the palm of the hand, the digital arteries are the only branches of the vessel which attain any size : there are four of these, the first supphing the ulnar side of the little finger, and the remaining three correspondint; each to the opposed sides of two fingers : the most external being between the middle one and the index. They occupy a situation super- ficial to the nerves and tendons, and continue forwards, each as a single branch, until they reach to the clefts of the fingers ; Mng in in- tervals between the commencing sheaths of the tendons, and limited in front by the trans- verse ligament of the fingers, and behind by the strong ligament on the heads of the metacar- pal bones. In this space lies also the similar digital branch of the median nerve, but beneath the artery, and at its inferior tennination, each bifurcates into branches for the neigh- bouring side of the fingers which bound the cleft. Here the vessels are crossed by the nerves, and in the remainder of their length, are situated along the border of the finger, to its termination, the nerve being anterior. At the extremity of the finger, the branch of each side gives off a twig to the under surface of the nail, and the remainder immediately unitinfr in an arch with the similar branch of the op- posite side, breaks up into a network, whose meshes thus form a highly vascular subtra- tum to the sensitive papillary surface which especially occupies this part. In its course along the finger, beside many smaller branches, each digital artery gives off a transverse branch ]ust above the several phalangeal articulations ; which, by joining with its fellow, forms an arch whence proceed the smaller vessels to the joint. Varieties of the radial and ulnar arteries. — The size of these vessels, together with the comparative exposure to mechanical injury which their situation involves, renders an exact knowledge of their distribution abso- lutely essential to the surgery of the upper extremity ; and the same causes also require that the more important varieties, which con- stitute so large a per centage of their acti^al numl)ers, should at least experience some consideration. In sketching out a few of these it is impossible to avoid acknowledging great obligations to Mr. Quain"s recent work, " The Anatomy of the Arteries," in which the number of subjects, which serve as the groundwork of the estimates, the evident care with which they have been examined, and the beauty of the illustrations, leave little to be wished for. Variefies of origin. — Rarely does either of the two vessels arise from the brachial at a point lower than the ordinary situation op- posite the coronoid process of the ulna : a higher division of this artery, or as it is called, a " high origin" of one of these its branches, is, on the contrary, by no means an uncommon occurrence. It is worthy of notice, that in the majority of these cases, there is no lateral correspondence of the variety, — in the 0[>- posite limb the distribution is the usual one. The most frequent of the two is Me liigh origin of the radial, which may come off from the axillary, or from the brachial artery in any part of its course. In this case, the remaining trunk, although directly continuous with the ulnar artery, and lacking the usual means of distinction from it, beitrs yet the name of brachial, since it generally possesses the ordi- nary relations and distribution of the latter vessel. L nder these circumstances, the radial passes down the arm from the place where it is given off. generally lying rather close to the brachial, and on its outer side, until it reaches the forearm : subsequently it preserves its usual arrangement and termination. But though, for the most part, its course is thus only altered by the possession of an additional por- tion in tlie upper arm, this irregularity is some- times associated with another which concerns its course, viz., a position of the artery super- ficial to the fascia; and here it would often have a close juxtaposition to the median basilic vein at the bend of the elbow, which careless- ness in venisection might render dangerous or even fatal. A similar deviation may obtain in the remainder of its course, placing it super- ficially to the supinator radii longus, instead of beneath its overlapping inner border ; or causing it to cross over the extensor tendons at the wrist instead of under them. The latter variety is frequently associated with another alteration in the course of the vessel, which, after giving off the superficialis volae at a point much higher than usual, immedi- ately turns round the outer border of the forearm, so as to leave this small branch alone occupying its ordinary position at the wrist. Other deviations are comparatively rare: — thus occasionally the vessel enters the palm in the second instead of the first inter- osseous space. Variations in its distribution appear chiefly dependent on its relative size. If smaller than usual, a kind of enlarged communicans ulnae reinforces its deep palmar arch, or gives off its radialis indicis and magna pollicis branches: or the compensative stream may arrive by another channel, viz., a dihited anterior inter- osseous to join the artery as it turns round the wrist ; or by a large posterior branch of RADIAL AND ULNAR ARTERIES. 227 the same vessel which meets it just before entering the metacarpal interspace. Where, as is by no means infrequent, the radial is larger than ordinary, its increased size is prin- cipally expended in supplying, through a large superficialis volae artery *, one or more of the outer digital branches which usually come from the superficial palmar arch: or, by means of a dorsal metacarpal of unusual magnitude, digital branches to the opposed sides of the index and middle fingers. The high origin of the ulnar is contrasted with that of the radial in another respect beside that of its lesser frequency, since it is almost always conjoined with an important difference in the situation of the vessel in the forearm, which lies superficial to the flexors ordinarily covering it, and immediately beneath the fascia: — sometimes it is even sub-cutaneous. Its course is also somewhat affected by this origin, the vessel approaching the inner side of the forearm at a higher point than usual : in other cases, however, it possesses almost a median position during the greater part of this region, and only turns inwards to its ordinary distribution near the wrist. In size, the ulnar artery is more frequently diminished than increased by variations. The decrease is compensated sometimes by a radial vessel supplying one or more of its digital branches or contributing to its palmar arch : at others, its long branch which accompanies the median nerve is enlarged to a vessel of considerable size, which similarly assists it ; while, in a few instances, the dilated anterior interosseous has an analogous termination. The origin of the interosseous artery is subject to some variation, being liable to occur as a divarication from the radial or brachial, or though rarely — from the axillary : its en- largement aids a deficient radial or ulnar vessel, just as its diminutive size is supplied by them. The branch with the median nerve enlarged to a " median " artery, has been already men- tioned ; it passes under the annular ligament as it enters the hand, and may reinforce the deficient radial or ulnar ; but most frequently the latter of the two, by joining the super- ficial palmar arch. Finally, as to the varieties in the hand, the mode in which a diminished superficial palmar arch is obviated, has already been described ; and an unusually small deep arch is compen- sated by the uhiar communicating, which is generally little inferior in size to the radial conti'ibution. For individually smaller digital branches are substituted enlarged dorsal meta- carpal ; and in the case of the magna pollicis the superficial palmar arch, the superficialis volas, or the median artery, may either of them make up the deficiency. It may be desirable to attempt a generaliza- tion of these special variations ; in order to this, let us return for a moment to the ordinary * Such a vessel, occupying from a high origin the place of the artery, but more superficial than it, has on this account been mistaken for a " hard " pulse, and the patient depleted accordingly. anatomy of the vessels of the forearm and hand considei'ing them as a whole. Such a view assisted somewhat, it must be confessed, by our knowledge of these varieties, would dis- cover in the forearm five longitudinal trunks, all possessing some feature, whether of size, length, or constancy, which especially recom- mends them to our notice. They are the radial, ulnar, and anterior interosseous vessels, together with the posterior branch of this lat- ter, and the branch with the median nerve. The anastomosis and distribution of the ex- tremities of most of these, forms around the wrist an arterial circle which is nmch more pronounced posteriorly.* In the hand, two arches which are continuations of the larger vessels occupy its surface of flexion, at diflc- rent heights and depths ; defended from the pressure inseparable from prehension by a strong fascia, whose protective effect is aided during flexion by a tightening muscle. They join by anastomosis with the extremities of the longitudinal vessels, or the imperfect anterior carpal arch. Three branches i-un lengthwise in most of the metacarpal interspaces ; one on the dorsum from the posterior part of the carpal circlet, two at different depths in the palm from these arches ; the dorsal and deeper palmar uniting at the superior extremities of those intervals, and all three inosculating at their inferior terminations near the clefts of the fingers. All the varieties above mentioned would be referrible to the increased developiuent either of one of these longitudinal branches, or ot some portion of this complete and large anas- tomosis. The several varieties are, in fact, an exaggeration by turns of a different vessel ; which in its course towards distribution may return its contents to the ordinary channel by any one of these series of inosculations ; whe- ther it be the superficial or deep arch, the posterior carpal arch, or finall}^ the superior or inferior extremity of the aforesaid interos- seous spaces. Thus from these vessels alone might be de- duced the law, of which the origin of the ob- turator from the epigastric, or the sublingual from the facial, are familiar and miportant in- stances; viz. that varieties of arteries occur as the exaggerations of an ordinary anasto- mosis f : while it is no less evident that the deviations are compensative in the strictest sense ; i. e. that the amount of blood entering the limb is no ways affected, for that an in. * Unless we considered the deep palmar arch as the anterior half of the carpal ring, a view Avhich the comparative infrequency of the minute "ante- rior carpal arch " would almost allow of. f It may be urged against such a generalization, " that it would scarce^ include the varieties of those vessels Avhich immediately spring from the heart or aorta : since anatomy shows the amount of their ordinary anastomosis, and the number, size, and regularity of the vessels effecting it, to be utterly disproportionate to the magnitude of these vari- ations." But a reference to the aorta and branchial arches, from which they are developed in the foetus, Avould again include them in the category of dilated inosculations. Q 2 228 RADIO-ULNAR ARTICULATIONS. crease of one is a diminution of some other vessel — or vice versa. The directness of these inosculations, and the frequency of these resulting irregularities together exert an important influence on sur- gical practice, which may be regarded in three points of view. Firstly, it necessitates unusual care in the ordinary operations ; since we may open an artery of dangerous size, where we least expect it. Secondly, it renders opera- tions undertaken on the vessels themselves liable to immediate non-success ; for we may find only a twig where we expect an artery of influential magnitude. Thirdly, it may also cause their mediate failure ; the width and number of the anastomosing chan- nels rendering deligation of a trunk useless, by filling it in a very short space of time below the ligature. Fortunately, however, the same position that renders them more liable to in- jury affords somewhat of a substitute for the operation by also exposing them more directly to external pressure. T/ie diseases and injuries of the radial and ulnar arteries scarcely offer peculiarities suffi- cient to demand a special notice. Aneurism as the result of disease, an ex- tremely rare occurrence in the brachial artery, would appear to be here still more infrequent ; and this remarkable immunity as compared with the lower extremity has been differently ascribed to a supposed greater vitality of the vessels nearer the heart, or with better reason to the less exposure of the arm to strains or shocks. Even this explanation, however, has so much imperfection about it, that it seems better to avoid theorising on the subject until more is known both of the physical relations of the different tubes to their central engine, and of the differences in the nature and ra- pidity of the nutrition of their coats, which may be presumed to exist. False aneurism may occur in any part of their course as the result of puncture or inci- sion of their coats; the sac of the tumour being formed by the nearest investing fascia, and lined by the areolar tissue of the neighbour- hood condensed by the pressure of the con- tents. These consist of blood, which is usually in considerable quantities, and has experienced more or less coagulation subsequently to its discharge from the opening of the artery which occupies some part of the inner surface of the cavity. But neither in these points, nor in the treatment usually adopted is there an3- thing which requires particular specification. The disease of the arterial system generally, which constitutes so frequent and important a part of the series of changes included in the term " old age," of course includes these ves- sels. Ossification of the radial artery is by no means rare, although in this extremity it is very unusual to find it occluding the tubes or leading to senile gangrene. Here, from the superficial position of this vessel, it is often a valuable index by which an insight is afforded into the condition of other and more important arteries. In this latter stage of the change the vessel is rather larger than normal, very hard, thick, and tortuous : while the impulse of the heart communicated to it by its contents, and tending to efface these abnormal curves, often almost lifts it from its situation at each stroke. In an earlier stage of the affection it is much less easily recognised, but even here the tactus eruditus may sometimes appreciate the change ; and though it is perhaps difficult to translate the sensation into words, such a pulse might be paradoxically described as being at the same time hard to the touch, and comparatively soft and yielding to the 2^ressure, while its beats are associated with unusually little ex- pansion, though they strike the fingers with more force. {William Brinton). RADIO-ULNAR ARTICULATIONS. {Articidations radio-idnaires — Verbindungen des Ellenbogenbeins mil der Speiche.) — Wherever the anterior extremity is modified to serve as an instrument of prehension, one chief part of the provision for greater freedom and facility of movement occurs as the correlative modifi- cation, not only of the two bones of the fore- arm, but also of the articulations which mutu- ally connect them at their upper and lower extremities. In man, in whom the arm, losing its locomotive, attains its most complete pre- hensile development, the radius enjoys a very considerable degree of motion around the ulna by means of these joints. And by the alternate preponderance of either of the two bones in the wrist and elbow joints which are situated at their opposite extremities, this mobility of the radius is increased, while the freedom of movement predicable of it becomes ex- tended to the hand which occupies its distal termination : and thus the rotatory movement which is gradually superadded to the ordinary flexion and extension of the limb finally reaches its maximum. In each of these articulations we shall separately describe, 1. Its anatomical consti- tuents— the several structures which serve to allow of, or to limit, motion. 2. The result of their functions — the movements of the joint. (1.) The upper radio -ulnar ai'ticidaiioii — whose elements are the head of the radius, the lesser sigmoid cavity of the ulna, the annular ligament, and a synovial membrane. The round head of the radius — represents in shape the upper part of a cylinder, or rather a horizontal segment of an inverted cone, which becomes continuous below with the shaft of the bone by means of a constricted neck. It thus offers two articular surfaces: one, a shal- low cup-shaped cavity which plays on the radial tuberosity of the humerus : another, the side of the cylinder, which has a linear mea- surement of about a quarter of an inch at its deepest part, where it corresponds to the lesser sigmoid cavity of the ulna and ends below in a prominent margin ; elsewhere it is nar- rower ; and subsides more gradually into the neck of the bone. These two smooth surfaces merge into each other at the angle where the base and circumference of the cylinder meet, RADIO-ULNAR ARTICULATIONS. 229 but it is to the latter only that our attention is at present directed. The sigmoid cavity of the ulna — is a depres- sion situated on the outer side of its upper ex- tremity, and, in respect of its position, it might be expressed as an articular facet seated on the external margin of the coronoid process. In shape it is somewhat quadrilateral ; and is concave in both directions, but most so in the anterio-posterior, which corresponds to the convexity of the head of the radius, and is also much the longest surface of the two. "With trifling individual variations, it usually forms about the fourth of a circle. Superiorly, it is separated from the greater sigmoid cavity by a smooth elevation directed from before backwards : anteriorly, inferiorly, and pos- teriorly, the border of this articular surface overhangs the coronoid process of the ulna, the concave upper part of its anterior surface, and its posterior surface respectively. The junction of the two latter sides of its margin is marked by a strong ridge, which commences the external border of the bone : and, fre- quently the antero-inferior angle gives off a similar prominence ; which, after a short course downwards, converges to join the preceding. Articular cartilage covers these surfaces of the radius and ulna. The annular or orbicular ligament — is the next constituent, and is a strong and some- what cord -like band of white fibrous tissue, which completes the remaining three -fourths of the articular circle left unaccounted for by bone. Its width is about one third of an inch, its direction is horizontal like that of the sig- moid cavity. It arises behind from the poste- rior margin of this surface, and partly from its inferior border, uniting beyond these with the periosteum covering the surfaces of bone over- hung by them. In front, it is inserted into the anterior margin in a similar manner. Above, it receives and is continuous with the anterior ligament of the elbow joint ; far- ther outward, it is also joined by the external lateral ligament of the same articulation. Its lower border is free around the neck of the radius. The synovial membrane is a process sent off from that which lines the articular surfaces of the elbow joint. A cul-de-sac passes down- wards into the lesser sigmoid cavity, extending to its inferior extremity, but around the neck of the radius, and between it and the orbicular ligament, the remainder of this circular pouch has a diminished vertical extent ; sufficient, however, to allow it to pass under the or- bicular ligament, and appear from beneath its lower border. The movement of the head of the radius at this articulation is one of simple rotation around its own axis ; since the articular sur- faces in contact with it together form a circle, in which its only movement can be a revo- lution. And, as above stated, about three- fourths of this circle is formed by ligament; the remainder by bone. But in addition to this chief provision for the limitation and di- rection of motion, the convex radial tuberosity of the humerus forms a kind of pivot, which is received into the cavity which occupies the upper surface of the radius, and, no doubt, steadies and assists the movement by tending still more to define the axis of this part of the bone. The articulation of the atlas with the odontoid process of the axis, offers many analogies to this of the railius and ulna both in the structure of the joint and in the re- sulting movements. (2.) The lower radio-ulnar articulation — is, in many respects, the reverse of the preceding ; since instead of presenting a cylindrical ex- tremity of the radius revolving within a con- cave facet of the ulna, the latter bone itself offers a rounded termination, on and around the outer side of which the radius plays by a concave articular surface. The constituents of the joint are, the surfaces of the radius and ulna just alluded to ; a fibro-cartilage which, with a kind of imperfect ligamentous capsule, forms the means of union of the bones ; and a syno- vial membrane interposed between their ar- ticular surfaces. The lower extremity of the radius — aj)- proaches somewhat to the form called by geometricians aparallelopiped. Its largest sur- faces are the anterior and the posterior : the upper is joined and surmounted by the shaft of the bone, and the lower enters into the formation of the wrist joint. The outer side is occupied by the tendons of the muscles which extend the thumb : and the inner, which looks slightly upwards, articulates with the ulna. This surface is quadrilateral, and of these the two antero-posterior sides are much the longest. The upper is nearly straight, the lower somewhat concave downwards to adapt it to the convex surface of the radio-carpal articulation ; and they slightly diverge behind so as to make the posterior vertical border almost twice as deep as the corresponding anterior side. The articular surface itself is concave from before backwards, taking a curve whose extent is about one fifth of a circle. The lower end or head of the ulna — is of even smaller size than the upper extremity of the radius which was previously described ; a condition which is in conformity with its slight share in the wrist joint. The base of this cylindrical head has a smooth surface and is almost circular in shape ; internally it offers a dej)ression bounded by the pro- minent styloid process extending vertically downwards; externally, a margin defines its separation from the articular facet which oc- cupies the outer part of the cylinder. This convex surface is usually a little longer in the horizontal direction than the corre- sponding radial concavity, forming about a fourth of a circle ; but in all other respects it is, as it were, moulded to it. Above, its margin projects beyond the constricted shaft. A layer of articular cartilage covers both these surfaces. Ligamentous fibres in sparing quantities, and with no very definite direction, unite the upper, anterior, and posterior borders (i 3 230 RADIO-ULNAR ARTICULATIONS. of these articular facets so as to result in a species of capsule. The triangular Jibro-cartUage is brought into view by removing the preceding ligament after laying open the wrist joint, and sepa- rating the two bones. Arising by a broad base from the sharp margin which separates the ulnar and carpal articulating surfaces of the radius, it passes inwards beneath the head of the ulna with continually diminishing width, until finally its apex is inserted into the base of the styloid process of this bone. At the commencement of this course it is nearly flat, though rather thicker at the margins than towards the middle ; indeed, it is by no means unusual to find a " perfora- tion " or deficiency in this part — but towards its apex its thickness is so much increased as to give it almost a cord-like form where it joins the ulna. It belongs to the class of fibro-cartilages, and Hke most of these, the proportions in which its component tissues are mixed vary greatly in different parts : thus the centre consists chiefly of cartilage, while towards its periphery it is almost purely ligamentous. Its lower surface is covered by the synovial membrane of the carpal articu- lation, and is in contact with the upper surface of the cuneiform bone. Above, it corresponds to the lower extremity of the ulna, and the structure itself is the medium by which that bone takes its limited share in the wrist joint. Its borders, looking forwards and backwards, are united with the anterior and posterior ligaments of this articulation. The si/novial membrane, sacciformis,^'' as it is usually called, is large and loose, and is not only interposed between the radial and ulnar surfaces, but is also continued inwards beneath the extremity of the ulna, so as to cover it and the contiguous upper surface of the trian- gular fibro- cartilage. In passing from one of these apposed surfaces to the other, it lines, for a very short distance, the capsule and the two ligaments of the wrist joint which unite them. The movement of the lower end of the radius may easily be deduced from the above description, where the shape of the articular surfaces and the attachments of the fibro- cartilage alike indicate a rotatory movement of this bone around the ulna ; since there is an almost complete correspondence between the apex of the ligament and the centre of that circle of which these articular surfaces would form a part. But although the motion at either of these articulations is thus no very difficult deduction from their anatomy, the mutual consistency of the two, or the movement of the radius as a whole, seems to have been much less un- derstood. The somewhat obscure language in which this has been described would allow us to imagine that a kind of rotation of this bone on its axis was supposed to result as the balance of the miovements which obtain at the several joints. These anomalies and in- consistencies have been cleared up by Mr. ,Ward, in his very able work on Osteology; in which he points out that the axes of the head and neck of the radius above, and that of the head of the ulna below (the evident centres of rotation in each case) are con- tinuations of each other, and form different portions of one and the same line, which is thus the real axis of the whole bone in its motions. In other words, the axis of the head and neck of the radius, prolonged down- wards, woukl fall upon a point in the lower surface of the ulna, the centre of the circle whereof the sigmoid cavity is a part. And this, he urges, will alone explain how the partial rotation of the bone is altogether in- dependent of any antero-posterior movement of its head, and occurs " without disturbance to the parallelism of the superior joint." Thus we might imagine the articulations of the forearm to be the immediate consequence of two chief necessities of movement ; one of flexion and extension of this segment of the limb, another of alteration of aspect of the terminal segment or hand ; the latter can scarcely be accomplished in any other way than by semirotation. The conditions of powerful flexion and extension are, on the contrary, best suited by a more or less gingly- raoid joint at each extremity; and the shape of the interlocking surfaces which forms the chief security of such an articulation, would render it insusceptible of this partial rotation. These requirements, incompatible of fulfilment by one bone, are met by the addition of another, to which the hand is attached. And now a new necessity arises ; for the superadded lever must be associated with the pillar previously existing, so far as regards the first movement, but dissevered from it as regards the second. This is accomplished by giving the radius a very limited participation in the elbow joint, a very considerable one in the wrist ; and by making the ulna supply the terminal fixatures of the rotating shaft. The peripheral and com- plete condition of the upper attachment, the internal or centric and incomplete state of the lower, which, like the shaft itself, is here re- duced to a part of a circle ; these are pro- visions which, like many met with in other parts of the body, at once economise means and preserve the symmetry of the limb. Pronation and siijiination. — The extremes of this rotation of the lower extremity of the radius constitute the states of pronation and supination. So far as these result from the movements of this bone, they are not quite opposite aspects of its surfaces, or of those of the hand, since -the angles which they mutually form in these conditions are scarcely equal to a quadrant and a half, or 135 degrees. And this fact, which the appearance of the articular surfaces alone would lead us to suspect, may be reduced to a certaintv by the very simple experiment of bending the forearm, and then from extreme supination pronating the wrist, and comparing the lines formed by its anterior surface in both these positions with each other, so as to take the angle through which the surface has passed. Or better still, since it removes all suspicion of interference with the KEN. 231 muscles that effect pronation, fix the condyles of the humerus by any means, and then re- peat the examination of these angles. Pronation and supination may, however, be carried far beyond this limit of the radial motion ; aided by powerful rotation of the humerus inwards and outwards respectively, the surfaces will attain to complete opposition of direction, or 180 degrees of intervening angle, and even to a variable distance beyond this which is, on an average, almost another quadrant. It deserves also to be noticed, that these movements are often converted into rotation around the axis of the lower part of the forearm and wrist, by a somewhat similar humeral movement. For example, simul- taneously with pronation, the lower end of the humerus is carried outwards and upwards, and a similar deviation is thus impressed on the ulna articulated with it, which extending to its lower extremity, results in the rotation of this part of the limb ; i. e. in the completion of pronation, without the usual advance of the inner border of the forearm towards the median line of the body. Dislocations of these joints. — At the upper of the two radio-ulnar articulations either bone may be thrown out of its place in several directions. Displacements of the ulna, how- ever, chiefly aiTecting the elbow joint into which it so largely enters, are included amongst those of this part ; and though those of the radius are, both in nature and effects, accidents of the radio-ulnar articulation, in practice it is very difficult to avoid considering together injuries which have so close a re- lation, albeit, strictly speaking, an accidental one. Hence the reader is referred for these to the article " Abnormal Conditions of the Elbow-joint." At the lower joint the radius and ulna may be displaced from each other by external force, or by the violent action of the muscles in extreme pronation or supination : but the latter is a very rare occurrence. Looking to this articulation only, it might be difficult to define which bone was dislocated : whether, for in- stance, the ulna was " dislocated backwards," or the radius *' dislocated forwards," since, in such a case, either of these phrases would equally express their altered relation to each other. It is most convenient to consider this question determined by the condition of the neighbouring wrist joint, and to instance those cases as dislocations of the radius where the extremity of this bone is located unnaturally forwards or backwards, both as regards the carpus and head of the ulna. And, similarly, where the wrist and radius preserve their ordinary relation, but the lower end of the ulna is displaced with respect to both ; here it will be better to consider the ulna as the luxated bone, even though the accidents might sometimes resemble each other in their causes as well as mode of production. The dislocation of the radius forwards is easily recognized by the styloid process of this bone and the trapezium no longer lying in the same vertical line ; and by the situation of the extrennty of the radius in front of the bones of the carpus, causing an unnatural prominence there. The luxation backwards would appear to be almost unknown, a reversal of these signs would indicate it. In both, the relative position of the ulna and wrist is little affected. In the dislocation of the ulna, the ordinary connection of the hand and radius being kept up, the pronation or supination of the limb becomes a feature of a very striking kind. The signs of the luxation backwards are ex- treme pronation, the head of the ulna pro- jecting beneath the skin at the back of the forearm, and the styloid process of this bone occupying a line posterior to the border of the wrist or the cuneiform bone. The dis- location forwards is of extreme rarity, but the above marks, nmtatis mutandis, would leave little room for doubt as to the nature of the accident. The diseases of these articulations offer no peculiarities which deserve a separate de- scription. {William Brinton.) REN* — THE KIDNEY (Gr. v^ of the Malpighian body. A large artery_^-^ breaks up in a very direct manner into a num- ber of minute branches, each of which sud- denly opens into an assemblage of vessels of far greater aggregate capacity than itself, and from which there is but one narrow exit. Hence must arise a very abrupt retardation in the velocity of the current of blood. The vessels in which this delay occurs are un- covered by any structure.* They lie bare in a cell from which there is but one outlet, the orifice of the tube. This orifice is encircled by cilia in active motion, directing a current towards the tube. These exquisite organs must not only serve to carry forward the fluid already in the cell, and in which the vascular tuft is bathed, but must tend to remove pres- sure from the free surface of the vessels, and so to encourage the escape of their more fluid contents. Why is so wonderful an ap- paratus placed at the extremity of each urini- ferous tube, if not to furnish water to aid in the separation and solution of the urinous products from the epithelium of the tube?" There is nothing which appears to afford greater support to 5lr. Bowman's theory than the structure of the kidney of the boa, when considered in connexion with the fact that the urine in this animal is excreted in an almost solid form. It will be rememberedf that the greater part of the blood supplied to the kid- ney of the boa is derived from a vein which comes from the posterior part of the body ; this vein forms the plexus which surrounds the uriniferous tubes, and from which, accord- ing to Mr. Bowman, the solids of the urine are excreted. The renal artery, which is com- paratively of small size, is distributed to the Malpighian bodies, as in the higher animals, and the efferent vessel joins the portal vein. The solid urine of the serpent seems a neces- sary consequence of the peculiar distribution of the blood-vessels ; the small Malpighian bodies pour out a scanty stream of water sufficient only to carry through the tubes the large quantities of solid matter which the more numerous and larger vessels distributed on the outer surface of the tubes are continu- ally supplying. * With reference to this point, fjc/e an^e, p. 248-9. t Vide ante, p. 250. 256 REN. Another fact confirmatory of Mr. Bow- man's theory has been observed by myself.* In examining the kidneys of persons wiio had died jaundiced, and in whose urine there had been a large quantity of bile, I observed tbat the tubes were stained of a deep yellow colour by the bile in their epithelical cells, and that this yellow colour ceased abruptly at the neck of the Malpighian capsule, and in no instance did it affect any part of the tissue of the Malpighian bodies. There are certain other pathological phenomena, which Mr. Bowman's theory very much assists to explain, and which in their turn afford important evi- dence in support of the doctrine in question. The office of secreting the solids of the urine is limited to the convoluted portions of the tubes. The straight tubes of the pyra- mids probably have no secreting power, but act merely as excretory ducts to convey the secreted products from the cortical portion of the gland. The different function of these two portions of the tubes is sufficiently mani- fested by two facts : — 1st. By the difference in the character of their epithehal lining ; 2dly. By the fact, that when the cortical por- tion of the kidney is the seat of a morbid deposit in consequence of the attempted ex- cretion of abnormal products by the epithe- lial cells in the convoluted tubes, the niedul- lary portion of the gland is very commonly free from all trace of the same morbid deposit. This is very frequently observed in instances of fatty degeneration, as well as in the earlier stages of the inflammatory diseases of the kidney. PART III. PATHOLOGY OF THE KIDNEY. It will not be possible within the limits of this article to give more than an outline of the pa- thology of the kidney. The subject is one of such great interest and importance that it re- quires a much more extended consideration than can here be assigned to it. The diseases of the kidney may be arranged in two distinct classes: the first class including those which are the result of some cause acting locally, such as retention of the urine in con- sequence of stricture, the mechanical irritation of a stone impacted in the kidney, or a blow on the loins ; while in the second class are in- cluded those diseases which are the result of a constitutional cause which acts upon the kidney by inducing an abnormal condition of the blood. We shall allude very briefly to the first class of diseases, and then proceed to the con- sideration of those diseases to which the kid- ney is liable in consequence of a deteriorated condition of the blood. Dheane of the Iddney from retention of urine. — Fig. 165. represents a condition of the kid- ney which commonly results from an im- peded escape of the urine. The ureter pelvis and infundibula become much dilated, and the cortical substance expanded and lobular on the surface, the depressions between the * Med. Cliir. Trans, vol. xxx. lobules resulting from the binding down of the tissue by the interlobular septa, in the Fig. 165. Section of the kidney fi-om a patient who had stricture. The pelvis and infundibula are much tli- lated, the cortical portion is expanded, and its suiface lobular. The parts are reduced about one third in the di-aAving. . intervals of which the glandular structure is protruded by the distending force from within. The mucous membrane fretjuently becomes ulcerated, inflammatory deposits occur in the substance of the kidney, and so the gland is destroyed by a slow atrophy, or more rapidly by suppurative inflammation. Both kidneys are usually affected, but in diflferent degrees. On a microscopical examination of the kid- ney thus diseased, pus and other inflammatory deposits are found. The deposits are not confined to the tubes, but they occur irregu- larly throughout the gland, so as in many instances to obliterate all appearance of tubu- lar structure. Disease of the Iddney from renal calcidi. — When a calculus forms in the kidney, it may lead to very different results according to its size and position. If of small size, it may pass down the ureter and so get into the bladder ; or if it be too large to pass through the ureter, it may, by becoming impacted in the canal, and so obstructing the flow of urine, give rise to a rapidly destructive sup-, purative inflammation, or it may lead to com- plete atrophy of the gland. It sometimes happens that several calculi become impacted in the pelvis of one or both kidneys, causing ulceration of the surrounding tissue, and leading in some instances to a complete dis- organisation of the gland. REN. 257 Disease of the hidney from external violence — is not of common occurrence. One case of the kind has occurred to myself. A strong man in robust health received a violent blow on the loins from a bludgeon ; he suffered much pain, and within a short time after the receipt of the injury he had haematuria. The bleeding recurred at intervals during several months, and was succeeded by a discharge of purulent matter with the urine. The purulent discharge continued for a period of more than a year, when the poor man died much emaci- ated. On a post mortem examination, the right kidney was found completely destroyed by suppurative inflammation ; there was no stru- mous deposit in the kidney or in any other organ. There was no calculus. The left kidney was quite sound. Extension of disease from other organs to the kidney. — The kidney sometimes becomes in- volved in malignant or other disease affect- ing the intestines and other adjacent viscera. Allusion has already been made to a prepa- ration in the Museum of King's College, in which there is a communication between an abscess in the psoas muscle and the canal of the ureter. Diseases resulting from a constitutional cause. — Scrofulous disease of the kidney occurs in the form of small scattered deposits of tuber- cular matter, or it presents itself in the form of a thick curdy deposit which leads to the formation of a large scrofulous abscess, the cavity of which is subdivided by septa formed by the thickened interlobular cellular tissue. (Jig, 166.) The scrofulous deposit commonly Fig. 166. Scrofulous abscess in the kidney. The cavity of the abscess is divided by septa, which are formed by the interlobular cellular tissue, thickened by an in- terstitial deposit of stmmous matter. The glandular structure has been destroyed by suppurative inflam- mation. extends over the mucous membrane of the ureter, which becomes much thickened. Acute suppurative nejjhritis is not a common disease, but it is a very serious and a very 1 fatal one. In one case it supervened upon ! VOL. IV. chronic disease of the kidney, in consequence of the intemperate use of fermented liquors by a man whose general health was much dis- ordered, and who had been subject for several months to successive crops of boils and car- buncles about the neck and shoulders. He died in about a week after symptoms of sup- purative nephritis had manifested themselves. The nature of the disease was detected at the very commencement by a microscopical exa- mination of the urine (JigAQl). Both kidneys Fig. 167, Deposit in the urine of a patient labouring imder acute suppurative nephritis, a, crystals of triple phosphate ; b, c, d, moulds from the tubes of the kidney, the last entangling pus corpuscles. Some free pus corpuscles are scattered about the field. Magnified 200 diameters. were much enlarged, evidently from a recent attack of acute inflammation, numerous small points of suppuration were scattered through them, and the left contained two large recent abscesses. This case occurred in King's Col- lege Hospital, under the care of Dr. Todd. Acute desquamative nephritis. — This form of disease occurs very frequently as a conse- quence of scarlatina, and is occasionally pro- duced by other animal poisons, as for instance that of typhus fever, small-pox, or measles. The same condition of kidney very commonly occurs amongst the poor in large towns and elsewhere, as a consequence of that deterior- ated condition of the blood, which results from an insufficient supply of animal food ; and it sometimes occurs as a consequence probably of a similarly deteriorated condition of the blood in persons who are much reduced by long-continued disease, as for instance secon* dary syphilis or chronic abscess. The kidney in these cases is enlarged, ap- parently by the deposit of a white material in the cortical substance ; the vessels in the cortical portion where they are not compressed by this new materia', are injected, and of a bright red hue ; the medullary cones are of a dark red colour, in consequence of the large veins which occupy these portions of the gland being distended with blood. The ap-» s 258 REN. pearance of the entire organ is quite that of a part in a state of acute inflammation. When the kidriey has been in a softened condition before the occurrence of the inflam- matory disease, as often happms in elderly persons, the lobules on the surface appear larger and coarser than natural ; the veins being less compressed than when the natural texture of the kidney is firmer and more un- yielding, are much distended with blood, so tliat the entire organ is of a dark slate colour. On a microscopical examination the con- voluted tubes are seen filled, in different de- grees, whh nucleated cells, difTering in no essential character from those which line the tubes of the healthy gland (fg. 168). The Fig. 168. Section of a portion of inflamed kidney. The tubes appear as if divided into distinct globular and oval portions ; this appearance results from the man- ner in which the tubes are packed in the meshes of the fibrous matrix, so as to be concealed where they are crossed by the fibrous tissue, and visible in the intervals. The tubes are rendered opaque by an accumulation of epithelium, the outline of the cells being invisible on accoimt of their being closely packed. A Malpighian body in the centre of the mass appears transparent and healthy. Magnified 200 diameters. Med. Chir. Trans, vol. xxx. Malpighian bodies are for the most part trans- parent and healthy, but the vessels of the tuft are sometimes rendered opaque by an accu- mulation of small cells on their surface. Some of the tubes contain blood, which has doubt- less escaped from the gorged Malpighian vessels. There is no deposit exterior to the tubes. The condition of the urine in these cases is clearly indicative of the process going on in the kidney. After it has been allowed to stand for a short time, a sediment forms ; and on placing a portion of this under the microscope, there may be seen blood-cor- puscles, with e()ithelial cells in great numbers, partly free and partly entangled in cylindrical fibrinous casts of the urinary tubes*, and very commonly numerous crystals of lithic acid are present {Jig. 169). As the disease subsides, which under proper treatment it usually does in a few days, the blood, fibrinous casts, and epithelial cells di- * The fibrinous moulds of the kidney tubes, as seen in albuminous urine, were first observed by the late Dr. F. Simon of Berlin. minish in quantity, and finally disappear ; but traces of the casts may be seen some days after the urine has ceased to coagulate, on the application of heat or nitric acid. Fig. 169. Portion of a tube much dilated and di^^ded by septa which correspond with the rings of fibrous tis- sue in the microscopic specimen. See fig. 149, h. The cluster about h includes tAvo fibrinous moulds of the urinary tubes, entangling epithelial cells and blood corpuscles, two free epithelial cells, and three crystals of lithic acid from the urine in a case of " acute desquamative nephritis." c, A mass of oily matter from the urine. d, A cluster of octohedral crystals of oxalate of lime. Magnified 200 diameters. Med. Chir. Trans. voL xxx. The changes above described as occurring in the kidney are the result of a modification of the natural process of secretion produced by the presence of abnormal products in the blood. These products are eliminated by an excessive development of epithelial cells which are thrown into the tubes and washed out with the urine. The desquamation from the inner surface of the tubes is analogous to that which occurs on the skin subsequent to the eruption of scarlatina. I have, therefore, pro- posed to apply the term " acute desquamative nephritis" to this form of disease.* Chronic desqiiamaiive 7iephritis is essentially of the same nature as the acute form of the disease. Its most frequent cause is the gouty diathesis, and it very rarely occurs except in those who are addicted to the use of alcoholic drinks.f In the earlier stage of the disease the kidney is of the natural size, or very slightly enlarged, and the structure of the organ appears confused, as if from the ad- mixture of some abnormal product ; there is * See the author's paper on this subject in the Med. Chir. Trans, vol. xxx. t This form of diseased kidney was first described by Dr. Todd, under the name of gouty kidney, in a clinical lecture which was delivered in June 1846, and published in the Medical Gazette for June 1847. In this lecture Dr. Todd alludes particularly to the destruction of the secreting cells, and the consequent deficient excretion of the solid constituents of the urine. REN. 259 also some increase of vascularity. As the disease advances, the cortical portion gradually wastes, and the entire organ becomes con- tracted, firm, and granular, the medullary cones remaining comparatively unaffected even in the most advanced stages ; simultaneously with the diminution in the size of the kidney there is a decrease of vascularity. These changes occur very gradually ; the disease having a duration in most cases of many months, and in some even of several years. On placing thin sections of the kidney under the microscope, some of the tubes are seen to be in precisely the same condition as in a case of acute desquamative nephritis : they are filled and rendered opaque by an accumulation within them of nucleated cells, differing in no essential respect from the normal epithelium of the kidney. This increase in the number, and this slight alteration in the character of the epithelial cells are the result of the elimination by the kidney of mal-assi- inilated products, which are being continually developed hi gouty and intemperate subjects, and which are not normal constituents of the renal secretion. There would evidently be a certain Umit to the number of cells which can be formed in any one of the uriniferous tubes ; for although some of the cells escape with the Hquid part of the secretion, and so may be seen in the urine, as in a case of acute desquamative nephritis, yet in many of the tubes the cells become so closely packed that the further formation of cells becomes impossible, and the process of cell-formation, and consequently of secretion within these tubes, is arrested. The cells, thus formed and fiUing up the tube, gradually decay and becomes more or less disintegrated. While these changes are occurring in the tubes, the Malpighian bodies frequently continue quite healthy, their capsules for the most part transparent, and the vessels in their interior perfect. From these vessels water, with some albumen and coagulable matter, is continually being poured into the tubes ; and, as a conse- quence of this, the disintegrated epithelial cells are washed out by the current of liquid flowing through the tubes, so that, on ex- Fig. 170. Casts of the urinary tubes, composed of fibrinous matter and disintegrated epithelium from the urine, in a case of chronic desquamative nephritis. Mag- nified 200 diameters. 3Ied. Chir. Trans, vol. xxx. amining the sedimentary portion of the urine, we find in it cylindrical moulds of the urinary tubes, composed of epithelium in different degrees of disintegration, and rendered co- herent by the fibrinous matter which coagu- lates amongst its particles, {fig. 170.) There is reason to believe that when the pro- cess of cell-development and of secretion have once been arrested by a tube becoming filled with its accumulated contents, the tube never recovers its lining of normal epithelial cells ; but when the disintegrated epithelium has been washed away from the interior of the tube, the basement membrane may be seen in some cases entirely denuded of epithelium ; in other tubes a few granular particles of the old and decayed epithehum remain {fig. 171.) ; Fig. 171. Section of a portion of Iddney, showing the tubes deprived of their epithelium by " chronic desquama- tive nephritis." The tubes as they lie packed in the meshes of the fibrous matrix have an appearance somewhat like that of globular and oval transparent vesicles or cysts. See Jiqs. 149 c and 150. Magnified 200 diameters. Med. Chir. Trans, vol. xxx. and again, in other instances, the interior of a tube which has been deprived of its proper glandular epithelium is seen lined by small delicate transparent nucleated cells {fig. 172.), Fig. 172. a, Section of a portion of kidney sho-n-ing tlie tubes lined by delicate transparent nucleated cells ; these cells have taken the place of the normal epi- thelium Avhich has been destroyed and swept away ; h, portion of the basement membrane of a tube de- prived of its epithelium, and contracted by its elas- ticity into an irregular globular form after being detached from the surrounding tissues ; c, portion of a tube much dilated, and bulging in the inter\-als of the matrix ; the constricted portions correspond with the surromiding rings of fibrous tissue. Mag- nified 200 diameters. 3Ied. Chir. Trans, vol. xxx. S 2 260 REN. very similar to those which may sometimes be seen covering the vessels of the Malpighian tuft. {Vide ante, Jig. 160.) After the tubes have lost their normal epithelial lining they may undergo one of the three following changes. 1. In some in- stances a pecuhar whitish glistening material is thrown into the tubes, some of which escapes with the urine in the form of cylin- drical moulds of the tubes, the appearance of which as seen in the urine is somewhat im- perfectly represented in fig. 173. The effect Fig. 173. Cylindrical moulds of the iirinaiy tubes composed of a'peculiar whitish glistening material, which is sometimes effused into the tubes in the advanced stages of chronic nephritis. From the urine. Mag- nified 200 diameters. of this material being effused into the tubes appears to be to obliterate them, and in some instances it apparently becomes organised into fibrous tissue. 2. Another change which the tubes un- dergo in consequence of losing their epithelial lining, is that of becoming atrophied. The power of separating the solid urinary consti- tuents from the blood resides in the epithelial cells which line the convoluted tubes. After the destruction of the cells the secreting power is lost, and as the normal action of the cells is certainly one of the essential conditions for maintaining the continued flow of blood to the tubes, so the removal of the cells is very commonly followed by a diminished afflux of blood, and a consequent wasting of the tubes. 3. Another change consequent upon the destruction of the epithelial cells is, in a cer- tain sense, the reverse of the preceding. The tubes apj)ear to retain the power of secreting serum, which fills and dilates the tube in con- sequence of its escape being prevented by epithelial debris choking up the lower ex- tremity of the tube. When once a tube is brought into this condition the process of dilatation may proceed to an almost unlimited extent. The tube bulges in the intervals of the fibrous matrix, and assumes the appear- ance represented in Jig. 172 c. These dilated tubes form the serous cysts which are so commonly seen in the cortical portion of the kidnc} . And it is remarkable that the moni- liform appearance of the dilated tubes, as seen in the microscopic specimens, is in many instances preserved even when the tube is so much dilated as to form cysts visible to the naked eye. {Fig. 174.) Fig. 174. Section of a portion of kidney in which serous cvsts have been developed. At a there is a series of four cvsts which are probably formed by the dilata- tion of a single tube. Compare this Avith fig. 172. From a specimen in the museum of King's College. Xatm-al size. Mr. Simon, in a paper on " Subacute In- flammation of the Kidney," * has propounded the theory that these cysts are greatly dilated epithelial germs, which become thus mon- strously developed in consequence of the destruction of the basement membrane of the tubes. If jMi\ Simon's account of these cysts were correct they would be in fact hydatid cysts. I am not prepared to deny that cysts are ever formed in the kidney by the development of isolated cells, as described by Mr. Simon ; it is very possible that such an occurrence may be not unfrequent, although it has hitherto escaped my observation. But there can, I think, be no doubt in the mind of any one who will carefully examine the subject, that the appearances described and figured by jNIr. Simon are produced simply by the packing of the tubes in the fibrous net- work which surrounds and partially conceals them. The best safeguard against a misin- terpretation of appearances in diseased speci- mens is a careful study of the healthy tissues. The peculiar cyst-like appearance of the tubes in cases of chronic nephritis results from the transparency of the tubes when deprived of their epithelial lining. This delicate and * Med. Chir. Trans, vol. xxx. REN. 261 transparent appearance of the tubes, which in the human kidney is the result of disease, may constantly be seen in the kidneys of some of the smaller animals ; as, for example, those of a mouse or a young rabbit. On examining thin sections of the kidneys of these animals it will be found that the delicate and semitransparent tubes, embedded in the surrounding fibrous network, constantly pre- sent more or less of the cyst-like appearance represented in fig. 171. It can scarcely be supposed that these appearances in the kidney of the mouse indicate the existence of isolated cells. In short, Mr. Simon's theory of renal cysts is so opposed to all analogy, and so en- tirely unsupported by facts, that it appears needless to occupy the time of our readers by a further detail of facts and arguments in opposition to it. Renal Hcemorrhage . — Under this head I will allude in a few words to a condition of kidney which I have never had an opportu- tunity of examining in the dead subject, but the nature of which is sufficiently manifested by the symptoms, and particularly by the con- dition of the urine, as ascertained by a micro- scopical examination during life. It is well known that great irritation of the urinary organs is a frequent consequence of the inter- nal administration of oil of turpentine, or the application of cantharides to the cutaneous surface. The urine in these cases is generally bloody, and is passed very frequently and in small quantities ; there is great pain and irri- tation about the kidneys and bladder ; but there are no symptoms of suppression of urine, such as drowsiness and tendency to in- flammation of internal organs, symptoms which are present, in a greater or less degree, in all cases of " desquamative nephritis." In the last-mentioned cases the epithelial lining of the urinary tubes is the seat of disease, and the imperfect elimination of the solid consti- tuents of the urine is a necessary consequence of the pathological changes which the secret- ing epithelium undergoes. In the condition of kidney now under consideration the Mal- pighian capillaries appear to be the only parts of the organ primarily affected. The irrita- tion produced by the turpentine or the can- tharides leads to engorgement of the Malpig- hian tufts, which commonly ends in rupture of the vessels, hsemorrhage into the tubes, and so the admixture of blood with the urine* On a microscopical examination of the urine fibrinous moulds of the tubes may be seen in great numbers (^fig. 175), blood corpuscles are entangled in the fibrine, but no epithelium is found combined with them. The inference is, that the epithelial lining of the urinary tubules is unaffected, and this conclusion is further supported by the fact already men- tioned, viz., the absence of the usual symp- toms resulting from a deficient excretion of urea and the other solid constituents of the urine. I have never seen a fatal case of strangury ; but when haemorrhage from the Malpighian capillaries has occurred in con- nection with other pathological conditions which have terminated fatally, haemorrhagic spots are seen scattered over the surface and through the cortical substance of the kidney. Fig. 175. Fibrinous moulds of the urinary tubules from the urine of a patient who had strangurv' after taking oil of turpentine. Some hlood corpuscles are entan- gled in the fibrine, as well as some octohedral cr\-s- tals of oxalate of lime which the patient was ex- creting at the time the hjemorrhage occurred. It is important to observe that in this form of fibrinous mould there is no epithelium from the tubes. Mag- nified 200 diameters. These spots, when submitted to a microsco- pical examination, are found to be composed of convoluted tubes filled with blood which has escaped from the 3Ialpighian capillaries, and after filling the capsule has passed into the tube {fig. 176). This fact was first pointed out by Mr. Bowman. F\g. 176. INIalpighian capsule and portions of the urinary- tubes containing blood which has escaped from the Malpighian capillaries. Magnified 200 diameters. See also fig. 149 d. The condition of kidney to which turpen- tine and cantharides cive rise mav result from s 3 262 REN. the irritation produced by certain products developed within the body. I have met with two well marked cases ot" this kind, in which the characters of the urine, as revealed by a microscopical examination, and the other at- tendant symptoms were the same. In both cases the s\mptoms were of short duration. When the blood in cases of haematuria is found to be moulded in the urinary tubes, there can of course be no doubt as to the haemorrhage being renal. During the first few hours of an attack of hfematuria it com- monly happens that the blood escapes from the kidney before it has coagulated, and at this period of the attack a large quantity of the blood will be found not to have the form of cylindrical moulds when examined by the microscope, but even in this case a careful examination will always detect some moukis, and that will suffice for the diagnosis; and at a later period of the attack, when the haemor- rhage occurs more slowly it will be found that nearly all the blood has been moulded into the urinary tubes before it has escaped from the kidney. When renal hemorrhage is pro- duced by the irritation of a calculus impacted in the pelvis or the ureter, the blood does not present the fibrinous moulds in question. Fatty degeneration of the kidney occurs un- der two distinct forms. In the first form of the disease in question, the kidneys are usually large, smooth, soft, pale, and mottled, and frequently they are scattered over with haemorrhagic spots. On a microscopical exa- mination, there is found to be a great increase in the size and number of the oil globules which exist in small quantities in the epithe- lial cells of the healthy gland. {See Jig. 164-.) The urinary tubes are filled and distended by the gorged epithelial cells, the dilated tubes compress the capillary plexus on their exterior, and hence, in consequence of passive conges- tion of the Malpighian vessels, the serum of the blood gets mixed with the urine, which thus becomes albuminous ; and when the ob- struction of the circulation is still greater the colouring matter of the blood escapes from the delicate Malpighian vessels and fills the tul)es, giving rise to the haemorrhagic spots before m.entioned. It is only that forni of epithelium whose office it is to excrete the solid portion of the urine which becomes gorged with oil ; the delicate epithelium covering the Malpighian vessels, as well as that which lines the straight tubes of the medullary cones, retains its nor- mal condition : the reason of these parts re- maining healthy while the epithelium of the convoluted tubes becomes greatly changed, as well in cases of fatt}- degeneration of the kid- ney as "in the desquamative inflammatory diseases before alluded to, will be manifest from a perusal of the second part of this article. In this form of simple fatty degeneration of the kidney, ail the tubes become almost uniformly distended with oil. In a slight degree, and in the earlier stages, it is often found after death in cases where there is no reason to suspect that it has been produc- tive of serious mischief during life : it is not until the fatty degeneration exceeds a certain degree that the functions of the organ become seriously affected. It is this form of fatty degeneration which frequently occurs in ani- mals, as a consequence of their confinement in a dark room, a fact which was first noticed by Mr. Simon.* The second form of fatty degeneration of the kidney differs from the first in having combined with it more or less of the changes characteristic of desquamative nephritis. The cortical portion of the kidney is soft and pale, and interspersed with numerous small yellow opaque specks. The kidney is generally en- larged ; sometimes it is even double the natu- ral size. In some cases the cortical portion is somewhat atrophied and granular ; but nei- ther in this nor in the first form of fatty degeneration of the kidney does that extreme wasting with granulation occur, which is so frequent a consequence of chronic nephritis. On a microscopical examination the convo- luted tubes are found filled in different degrees with oil, some tubes being quite free, while others are ruptured by the great accu- mulation in their interior. The opaque yellow spots scattered throughout the cortical por- tion are neither more nor less than convoluted tubes distended, and many of them ruptured by their accumulated fatty contents. The cells which contain the oil are for the most part smaller, more transparent, and less irregular in their outline than the ordinary healthy epithe- lium ; they are increased in number, and many of them are so distended with oil as to appear quite black. In parts of the same kidney there may commonly be seen some of the appearances already described as character- istic of desquamative nephritis. This form of disease is very commonly associated with fatty degeneration of the liver, but less frequently so than the first form of fatty degeneration of the kidney. The condition of urine connected with this form of renal degeneration is usually as fol- lows : — The quantity is small, the sp. gr. rather above than belov, the healthy standard ; it is generally very albuminous, and sometimes bloody. On a microscopical examination of the sediment which is deposited after stand- ing for a few hours in a conical glass, there may be seen the fibrinous moulds of the tubes so often alluded to, frequently entan- gling blood corpuscles and epithelium. But the main point to be attended to is this, that many of the epithehal cells are more or less distended with oil. (See Jigs. 149 and 164.) This fatty condition of the epithelium indi- cates with certainty the existence of one of the most serious and intractable diseases to which the kidney is liable. The majority of the cases of acute desquamative nephritis, and many of the chronic cases, end in complete re- covery ; but fatty degeneration of the kidney almost invariably leads to general dropsy and * Med, Chir. Trans, vol. xxix. KEN. 263 a fatal termination. It is therefore as import- ant to distinuuish between acute or chronic nephritis and fatty degeneration of the kidney as it is to distinguish acute pneumonia or chronic bronchitis from tubercular disease of the lung ; and the diagnosis of the renal disease may be made with as much ease and certainty by a microscopical examination of the urine as that of the pulmonary disease by auscultation and percussion of the chest. The three forms of disease just alluded to, viz. acute and chronic desquamative nephritis, and fatty degeneration of the kidney, include the greater number of those cases to which the term " Bright's disease" is commonly applied. On an inspection of the plates in the 1st vol. of Dr. Bright's well known Medical Re- ports, it is evident that more than one form of disease is there described by that distinguished physician. In a paper published two years since*, I maintained that the term Bright's disease should be confined to those cases in which there is fatty degeneration of the kidney, but after a further consideration of the subject, I am of opinion that if the expres- sion " Bright's disease" is retained it should be used only as a generic term to include several diseases, the existence and the im- portance of which were first made known by Dr. Bright. In order to convey a precise idea of the particular form of Bright's disease al- luded to, it is clearly necessary to use some terms having a more definite meaning, and I have suggested some which appear sufficiently expressive for the purpose. Hydatids are occasionally found in the kidney. Dr. BaiUief was well aware of the distinction between true hydatid cysts as they are found in the kidney and the more common serous cysts, which he correctly supposed to arise from an expansion of some of the natural tissues of the kidney. He mentions one case of hydatids in the kidney, in which there was a discharge of these bodes with the urine. It is probable that in every case of hydatid disease of the kidney, the nature of the affection might be ascertained by a careful examination of the urine. I have already stated that if Mr. Simon's account of the common serous cysts were a correct one, they would be in fact hydatid cysts, and as they would continually escape with the urine, they might be detected by a microscopical examination of the liquid. Assuming, how- ever, that they are dilatations of the tubes, it is not surprising that they should never be found in the urine, and that they cannot be dissected out from the kidney after death. Cancer of the kidney is less uncommon than it was formerly supposed to be. It is rarely limited to the kidney, and in the great majority of cases, where other parts are im- plicated, the disease has obviously originated in some one or other of these parts. % Can- * Med. Chir. Trans, vol. xxix. t The Morbid Auatomy of tlie Human Body. By Matthew Baillie, M.D. X The Nature and Treatment of Cancer. By Walter Hayle Walshe, M.D. cer less frequently affects the bladder and kidney simultaneously than might be ex- pected. M. Rayer and Dr. Walshe have ob- served the frequent co-existence of cancer of the liver and right kidney, and of the adjacent parts of the stomach on the descending colon and the left kidney. In thirty-six of the cases collected by Dr. Walshe, the anatomical state is described with considerable accuracy. " In thirty-one of these, pure encephaloid or one of its va- rities, was the species of cancer observed ; scirrhus in five only, — two of them of doubt- ful character ; while colloid did not, in any instance, occur in this situation. Encepha- loid exhibits itself in all degrees of consis- tence, and in several of its varieties. Among these varieties, the haematoid may almosit be considered frequent, as compared with its rarity in other internal organs. Encephaloid occurs in the infiltrated and tuberous forms ; the former more especially when the disease is primary, the latter when secondary. Can- cerous infiltration (as organic diseases gene- rally) commences in the cortical substance. This structure may, in some instances, dis- appear altogether under the influence of the accumulating cancerous matter, without the tubular substances having suffered in the least. The nodular form of the affection like- wise originates in the cortical substance, ge- nerally near the surface ; as the masses en- large, they become prominent on the surface, and assume the appearance of having formed between the surface of the kidney and its capsule." The renal tissue between the can- cerous masses is sometimes quite healthy; but in other instances it is congested, in- flamed, or actually in a state of suppuration, the pus being infiltrated or accumulated in a single spot. Melanotic discolouration of the cancerous masses is occa:>ionally, but rarely, witnessed in the kidne}'. In thirty-five cases of renal cancer, the disease affected both organs sixteen times; the right alone thirteen times, the left alone six.* In concluding this brief sketch of the pathology of the kidney, I will venture to predict that, within a very short space of time, the diseases of the kidney will be more completely and generally understood with reference to their pathology, diagnosis and treatment than those of any other organ. There are two circumstances which justify such an anticipation : — I. There is perhaps no important organ in the body whose minute structure has been so com- pletely and so clearly demonstrated as that of the kidney has been by Mr. Bowman. And 2nd, The morbid deposits or accumulations to which the kidney is liable occur, almost without exception, in such a situation, within the uriniferous tubes, that portions of these materials are being continually washed out by the stream of liquid which is poured into the extremities of the tubes, and so they come within the sphere of our daily obser- * Dr. Walshe. Op. cit. s 4 264. REPTILIA. vation ; thus affording the pathologist and the practitioner an opportunity of ascertaining the nature and tracing the progress of disease which is not presented in the case of any other internal organ. Bibliography. — Xormal AxATom' axd Phy- siology.— Bellini, Excercit. Anat. de Structiira Eenum, Florence, 1662, Leyden, 1711. Albinus, Dissertatio de Poris, 1635. Malpighi, Opera Omnia, Lugd. Bat. 1637. Ruysch, Opera Omnia, Amster- dam, 1700. Ruysch, Opera Omnia, Amsterdam, 1733. Boerhaave, Institut. Med., Lugd. Bat. 1721. Bertin, Memoires de I'Acad. des Sciences de Paris, 1744. Ferrein, Memoires de I'Acad. des Sciences de Paris, 1749. Haller, Elementa Physiologife Corporis Humani, Lausannte, 1757. Schumlansky, De Struc- tnra Eenum, Argentor, 1788. Eysenhardt, Diss, de Structura Renum Observ. Mic, Berlin, 1818. 3Ieckel, Menschliche Anatomie, Halle and Berlin, 1820. Ja- cobson, Isis, 1822, and Edinb. Med. and Surg. Jom-- nal, 1823. Huschke, Isis, 1828. 3Iuller, De Glandu- lai'um Secernentium Structura, Leipzig, 1832. Lau- rent, De la Texture et du Developpement de FAppareil Urinaire. These de Concours, Paris, 1836. Berres. Anatomie der Mikroscopisclien Gebilde, Yienne, 1837. Krause, a Mailer's Archiv., 1837 ; b Hand- bucli der Anatomie, Hanover, 1848. Henle, 3Ii(ller's Archiv., 1838. Cayla, Obser\'. d' Anatomie Micros- cop, sur le Eein des Mammif eres. These, Paris, 1839. Gluge, Anatomisch-Mikroscopische Untersuchmigen, cah. i. Minden, 1839. Wagner Physiologie, Leip. 1839: Eng., by Dr. Willis, 1844. GerZ*^r, Handbuch der Allgemeinen Anatomie, Bern. 1840. Vogel, Gebrauch des Mikroskops, Leipzig, 1841. Henle, Allgemeine Anatomie, Leipzig, 1841. Midler, Yer- gleichende Anatomie der Myxinoiden. Berlin, 1841. Boivman, Philosophical Transactions, part i. 1842. Goodsir, Monthly Journal of INIedical Science, 1842. Reichert, 3Iuller's Ai-chiv., 1843. Gruby, Ajmales des Sciences Xatm*., vol. xvii. 3Iidler, Handbiich der Physiologie, 4th ed. Coblence. Owen, Lectures on Comparative Ajiatomy, vol. i. 1843. Gerlach, Muller's Archiv., 1845. Bidder, Muller's Archiv., 1845. Kolliker, Muller's Ai-chiv., 1845. Toynbee, Medico-Chir. Trans, vol. xxix. 1846. Mandl, Anatomie Microscopique, 1847. On the subject of the Development of the Kidney reference may be made to the article Ovum. Pathology. — In addition to works on the prac- tice of Medicine and on general Pathological Ana- tomy, the following books and papers may be con- sulted.— Blackall, Obser^^ations on the Xature and Cure of Dropsies, and particularly on the presence of the coagulable part of the Blood in Dropsical Urine, London, 1813; 3d edition, 1818. Bright, Eeports of Medical Cases, 3 vols. 4to, 1827—1831, and papers in the Guy's Hospital Eeports. Rayer, Traite' des Maladies des Eeins. Prout, On Stomach and Eenal Diseases. Christison, On Granular De- generation of the Kidneys, 1839, and in the Library of Practical Medicine. ^ F. Simon, Handbucli der Medizinischeu Chemie, translated by the Sydenham Society. Hecht, De Eenibus in Morbo Brightii de- generatis, Berlin, 1839. Gluge, Anatomisch-Mikro- scop-Untersuchungen, Jena, 1841. Vogel, Icones Histolog-iCc-B Pathologicte. Henle, Henle imd Pfeuf- fer's Zeitschrift, 1842. Heller, Archiv. fur Physiol, und Pathol. Chemie und Mikrosk. band ii. Scherer, Chemische und Mikroskop. Untersuch., Heidelberg, 1843. Valentin, Eepertorium, 1837—1838. Can- statt, De Morbo Brightii, Erlangen, 1844. Eichholtz, Muller's Archiv., 1845. R. B. Todd, Clinical Lec- tures on Dropsy with Albimiinous Urine, Medical Gazette, 1845 ; and on Gouty Kidney, in Medical Gazette, 1847, Busk, Medic, Chir, Trans, vol, xxix. J. Simon, Med. Chir, Trans, vol. xxx. Malmsten, Ueber die Bright'sche nierenkrankheit, Bremen, 1846. PeacocA, Monthly Journal of Medical Science, 1846. G. Johnson, Med. Chir, Trans, vols. xxix. and xxx. Eeports of the Pathological Society of London, 1847 — 1848. (^George Johnson.) REPTILIA. — A very extensive and im- portant class of vertebrate animals, inter- mediate in their organization and general eco- nomy between fishes and the warm-blooded, air-breathing birds and quadrupeds, from both of which reptiles are distinguished by the following characters* : — Reptiles have the heart disposed in such a manner, that, on each contraction, it sends to the lungs only a portion of the blood which it has received from the various parts of the bod}^ and the rest of that fluid returns to the several parts without having under- gone the action of respiration. From this it results, that the oxygen acts on a less portion of the blood than in the mammifera. If the quantity of respiration in the latter animals, in which the whole of the blood passes through the lungs before returning to the parts, be expressed by unity, the quantity of respiration in the reptiles must be expressed by a fraction of unity. In consequence of this low^ degree of re- spiration, reptiles have cold blood, and their muscular power is less than that of quad- rupeds, and, d fortiori, than that of birds. Accordingly, they do not often perform any movements, but those of creeping and of swimming ; and though many of them leap, and run fast enough on some occasions, their general habits are lazy, their digestion slow, their sensations not acute, and in cold and temperate climates they pass almost the entire winter in a state of lethargy. Their muscles preserve their irritability much longer than in the higher classes. Their heart will beat for several hours after it has been plucked out, and its loss does not hinder the body from moving for a long time. In many of them, it has been observed that the cere- bellum is remarkably small, which perfectly accords with their little propensity to motion. Reptiles are provided with a trachea and larynx, though the faculty of an audible voice is not accorded to all of them. Not pos- sessing warm blood, they have no occasion for integuments capable of retaining the heat, and they are covered with scales, or simply with a naked skin. The females have a double ovary, and two oviducts. The males of many genera have a forked or double organ of intromission. Reptiles do not sit upon their eggs ; hence the latter have generally onl}^ a membranous envelope. In many of the reptiles which lay eggs, especially in the colubri, the young one is already formed, and considerably advanced in the egg at the moment when the mother lays it ; and it is the same with those species which may, at pleasure, be rendered vivipa- rous by retarding their laying. The quantity of respiration in reptiles is not^fixed, like that of mammifera and birds, * Cu\-ier, E^gne Animal, t. ii. REPTILIA. 265 but varies with the proportion which the diameter of the pulmonary artery bears to that of the aorta. From this proceed diffe- rences of energy and sensibiUty much greater than can exist between one mammiferous animal and another, or one bird and another. Accordingl}', the reptiles exhibit forms, movements, and properties much more various than the two preceding classes ; and it is more especially in their production that nature seems to have sported in the formation of fantastic shapes, and to have modified in all possible ways the general plan which she has followed for vertebrated animals. The comparison of their quantity of respi- ration and their organs of motion has, how- ever, given foundation for their separation into three distinct orders, viz. : — 1st, The Chelonians, or Tortoises (Che- Ionia), in which the body, supported on four legs, is enveloped by two plates or shields, formed by the ribs and the sternum. 2d, The Saurians, or Lizards (Sauria), in which the body, supported on four or on two feet, is covered with scales. 3d, The Ophidians, or Serpents (Ophi- dia), in which the body is always destitute of limbs. order I. CHELONIA. Family 1. — Testudinid^e. Testudo (Land Tortoise), Emys (Fresh- water Tortoise), Chelonia (Turtle), Cheljs, Trionyx. order II. SAURIA.* Family 1. — CRocoDiLiDyE. Gavial, Crocodilus, Alligator. Family 2. — Lacertid.e. Monitor, Crocodiku-us, Tupinambis, Ame- iva, Lacerta, Algyra, Tachydromus. Family 3. — Iguanid^. Stellio, Cordyliis, Stellio, Doryphorus, Uro- mastixy Agama, Agama, Tapayes, Tra- peluSy Leiolepisy Trojndolepis, Leposoma, Calotes, Lophyrus, Gonocephalus, Lyrio- cephalus, Brachyloplms, Physignathus, Is- tiurus, Draco, Sitana, Iguana, Ophryessa, Basiliscus, Polychrus, Ecphimotes, Opiu- ms, Anolius. Family 4. — GECKOTiDiE. Gecko, Platydactylus, HemidactyluSy Theca- dactylus^ Ftyodactylus^ Splieriodactyliis , Slenodactylits, GymnodactyluSy Phyllunis. Family 5. — CuAaiyELEONiDiE. Chamaeleo. Family 6. — SciNCiDyE. Scincus, Seps, Bipes, Chalcides, Chirotes. ORDER III. OPHIDIA.f ^ Family 1. — Anguidte. Anguis, Pseudopus, OjihisauruSy Anguisy Acontias, * ffuZ^o;, a lizard, f o(fi?, a serpent. Family 2. — SERPENTiDiE. Amphisbaena, Typhlops, Tortrix, Boa Scytaliis, Eryx, Frpeloiiy Coluber, Py- thoriy Cerberus, Xenopeltis^ Hcterodon, Hiirriay Dipsas, DendrojMs, Dryimis, Dryophys, Oligodon, Acrochordus, Cro- talus, Trigonocephalus, Vipera, Kaia^ Flaps, Afio'uriis, Platurus, Trimeresurus^ OplocephaluSy Acanthophis, Echis, Lan- gaha, Bongarus, Hydrus, Hydrophis, Pe- lamides, Chersydrus. Family 3. — C^ciliad^. Caecilia. Osteology. — The Chelonian reptiles are distinguished from all other vertebrata by the pecuHar construction of their skeleton ; the bones of the thorax being in these re- markable animals literally placed externally so as to form a suit of armour that encloses the muscles as well as the viscera, and within which the bones both of the shoulder and of the pelvis are lodged. The greater part of the dorsal shield or carapax is formed by eight pairs of ribs {fig. 177, i) united to each other towards the mesial line by a longitudinal series of angular plates, which are in fact the spinous processes (jie ural spines^ of as many vertebrae spread out horizontally. The ribs are connected by suture to the margins of these plates, and likewise to each other, either along their whole length, or to a greater or less extent, according to the species or the age of the animal. In front of the carapax there are eight vertebrae which do not enter into its compo- sition {fig. 177, e) : of these the seven anterior ones, which are ordinary cervical vertebrae, are quite free in their movements. The eighth vertebra, which may be called the first dorsal, is placed obliquely between the last moveable cervical and the first vertebra entering into the composition of the carapax ; posteriorly this vertebra (the eighth) has its spinous process somewhat elongated and slightly en- larged, for the purpose of its attachment by synchondrosis to a tubercle that is situated upon the lower surface of the first of the series of the mesian plates of the carapax. The ribs which, by their external broad plates, enter into the composition of the ca- rapax, give off from their inferior surfaces a process which corresponds with what in ordi- nary skeletons is called the head of the rib. This process is always connected with the spine between the bodies of two contiguous vertebrae, as are the heads of the ribs in other animals; and, carrying out the comparison, that part of the ribs which articulates by suture with the median plate may be regarded as the " tubercle," only here it is connected with the expanded spinous process instead of the transverse. In the Turtles the ribs are not united to each other throughout their whole length; towards their external extremities there only remains the narrow central portion, the inter- vals between the contiguous ribs being in this 266 REPTILIA. Fig. 177. Skeleton o f Tortoise. A, siapenor maxilla ; b, inferior maxilla ; c, ossiculum auditus ; D, os hvoides ; E, cervical vertebrae ; F, dorsal vertebrje ; G, sacrum ; h, caudal vertebrse ; i, dorsal ribs ; K, marginal scales ; x, scapula ; o, coracoid bone ; p, os humeri ; Q, radius ; r, ulna ; s, bones of the carpus ; t, metacarpal bones ; r, digital phalanges ; v, pelvis ; w, femur ; x, tibia ; t, fibula ; z, tarsus ; je, metatarsus ; A. v., phalanges of the foot. case filled up with a cartilaginous membrane. In the carapax of fresh-water tortoises (Emys), and in the Chelides, the interspaces between the ribs in time become completely filled up, and the ribs are connected by suture, through- out their whole extent, to each other and to the marginal pieces (k). The marginal pieces (Jig. 177, p) form a sort of osseous frame composed of a series of bones, eleven in number on each side, which are united together hy suture, and likewise con- nected with the extremities of the ribs. In the Tortoises this connection with the ribs is effected by suture, but in the Turtles and other genera having the extremities of the ribs narrow, their apices are implanted in fossae excavated in the marginal plates, where they are fixed by a species of s} nchondrosis. These marginal plates cannot be otherwise regarded than as the representatives of the sternal ribs of the Crocodiles and other Saurians ; the two first and the two last, like the abdominal ribs of the Crocodile, being de- veloped without the presence of any dorsal ribs in correspondence with them. In the Soft-Tortoises (Trionyx) the marginal pieces are never ossified, but are represented by a cartilaginous rim, in which sometimes osseous particles are sparingly deposited. The ventral cuirass of the Chelonian rej)- tiles, called the plastrum, is exclusively formed by the sternum, which in this race of animals seems to attain its maximum of development. It consists invariably of nine pieces, eight of which are pairs; while the ninth, situated between the four anterior ones, is central and azygos. These elements of the sternum have been well-named by Geoftroy St. Hilaire in ac- cordance with the situations that they occupy. The anterior pair ai-e the ephtemcil pieces, and the pair situated behind these the //j/o-sierna/s. In the centre bounded by the above four bones is the azygos piece named the e?iio- sternal. The pair situated immediately pos- terior to the hyosternal are called the hi^po- sternal pieces, and the two which terminate the plastrum xqj/io-sfenials. The sacral and caudal vertebra return to the usual arrange- ment, being all free and inoveable, having their bodies concave in front and convex be- hind, and their apophyses as in ordinary ver- tebrffi. Their number varies in different species from eight to twenty-seven. The scapular apparatus is contained in the interior of the thoracic cavity. It consists of a remarkably shaped three-branched bone (Jig. 178.), which is suspended on each side by a ligamentous attachment beneath the second vertebra of the carapax. The branch which is thus suspended ( a), notwithstanding its strange position inside the thorax, is the scapula ; the branch b Cuvier, after the ma- turest deliberation, decided to be its acromion process ; while the flattened bone c directed backwards, he considers as being incontest- ably the coracoid bone. This three-branched shoulder, with its almost cylindrical scapula. REPTILIA. 267 and an acromion process that almost equals it in size, is quite peculiar to the Chelonian rep- Fig. 178. Scapular Apparatus of Clielys. a, scapiila ; b, acromion process ; c, coracoid bone. tiles, nothing like it existing in any other ver- tebrate animals : nevertheless, the relations of these bones, and the muscles derived from them, prove clearly enough their identity, and allow of strict comparison with those of other races of vertebrata. The pelvis is always composed of three distinct bones on each side, which contribute, as in quadrupeds, to the formation of the coty- loid cavity, viz. theiUum (fig. 179, a.), which is Fig, 179. Pelvis of the Turtle. a, OS ilii ; b, os pubis ; c, os ischii. of an elongated form, and attached by liga- ments to the transverse processes of the sacral vertebrae, as well as to the neighbour- ing part of the eighth pair of dilated ribs : secondly, the pubis b, and the ischium c, both of which, expanding as they descend towards the p^astrum, terminate by joining their fellows of the opposite side. The cylindrical bones of the extremities resemble those of other four-footed reptiles, and present no peculiarity worthy of special notice, except in a geological point of view. In the turtles, all the bones of the carpus are flattened, and of a squarish form. In the first row there are two bones {fg. 160, r, d.) con- Fig. 180. Anterior extremity of a Turtle. (^After Cuvier.') nected with the ulna ; and in the second row there are five smaller ones (1,2, 3, 4, 5.), to which are appended the five metacarpal bones. In addition to the above, there is an interme- diate bone (e), situated beneath the ulnar car- pal bone (c), and above the second and third bones of the last row, (2, 3.) This piece, Cuvier thinks, corresponds with the disn)en-- bered portion of the trapezoid bone, met with in monkeys. Lastly, there is a great crescent- shaped bone ( /), which is adherent to the ulnar margin of the piece which supports the metacarpal bone of the little finger ; this is the OS pisiforme, although its situation is so low down. Between the bone (1), which supports the metacarpal bone of the thumb, and the ra- dius (a), the connexion during a long period is effected entirely by ligaments, without any appearance of the great scaphoido-semilunar bone which exists in the other sub-genera, but with age a small ossicle makes its appear- ance in this situation. In very large indivi- duals, the two antepenultimate bones of the second row are consolidated into one. The metacarpal bone of the thumb is 268 REPTILIA. short and broad ; the others are all long and slender. The little finger has only two pha- langes, and is not longer than the thumb, so that the whole hand has a pointed shape. The thumb and the index finger only have their last phalanx armed with a nail. In the land tortoises (Jig. ISl.), itisneces- Fig. 181. Anterior extremity of the Tortoise. sary to admit that there are only two phalanges to each finger, or else to suppose, either that the last row of carpal bones is wanting, or that the metacarpal bones are deficient. By compa- rison, however, with the hands of fresh-water tortoises, it is evident that the bones present belong to the carpus and metacarpus. This being allowed, the carpus is found to consist of a large radial or scaphoido-semi- lunar bone (a), of two ulnar bones (c, d.), which are nearly of a square shape, of five bones of the second row (J, 2, 3, 4, 5,) sup- porting the metacarpal bones, and of an inter- mediafe bone (tiguou3 vertebrae are REPTILIA. 273 connected together by very perfectly con- structed ball and socket joints, each vertebra presenting a concavity in front, and a convex ball upon its posterior aspect ; the plane of the circumference of the articulating surface being oblique from before to behind. The spinous apophyses are generally elon- gated and flattened, being prolonged poste- riorly to the articular a])ophyses, wiiich they partially overlap. The articulating processes are of two sorts ; some facing outwardly, represent ordinary ar- ticulating apophyses, \vith horizontal facets. The second face inwards, and are situated at the base of the spinous process. These apo- physes are so arranged, that, as in the lum- bar vertebrae of some Edentata amongst quad- rupeds, two vertebrae are articulated toge- ther by a double tenon received into a double mortice, the only difference being, that the facets of the upper tenon and mortice are continuous, and form with each other an acute angle. The articular facets, without including those of the bodies, are twelve in number for each vertebra ; an arrangement which re- stricts the vertical movements of the spine very materially, whilst at the same time it permits very free motion in a horizontal di- rection. The transverse processes are very short and scarcely perceptible, except by a tubercle, which offers two facets for articulation with the ribs. In the caudal vertebrae, however, the transverse processes are much longer, and inclined downwards ; they are even double to- wards the anterior part of the caudal region. In almost all serpents, the body of the ver- tebrae presents inferiorly a prominent longitu- dinal crest, which very generally terminates behind in a prominent spine, that is directed more or less towards the tail. In some ge- nera, as in Crotalus, for example, this s[)ine is even longer than the superior spinous process, and moreover is very frequently double. The arrangement of the articular processes described above is not met with in the genera Anguis Cecilia, in which it resembles what is foiuid in lizards ; and in Amphisfcsna, Ert/x, &c., traces, merely, of either superior or in- ferior spinous processes can be detected. The ribs of serpents are enormously nume- rous, their number varying, according to the proportions of the species, from 51 pairs (S/ieltoj)usic7c), up to three hundred and twenty pairs {Python). Each pair of ribs is move- ably articulated, by nieans of two slight con- cave surfaces, with corresponding articulating facets of the transverse processes of the cor- responding vertebra, forming a kind of double ball and socket joint, which allows of an un- usual extent of motion. There is no vestige of a sternal apparatus in any of the Oj)hi-. dian reptiles, but each rib terminates by a single tapering cartilage, which is attached by muscular connexions, to be described hereafter, to the abdominal scuta of the inte- gument. Myology of Chelonian Reptiles. — In the VOL. IV. Chelonian reptiles*, the cervical portion of the spine is composed of long and very moveable vertebrae, which form a curve, the concavity of which is upwards, whilst the dorsal region is converted into a broad immoveable shield by the consolidation of the ribs and vertebrae : there consequently cannot be any muscles of the back, whilst those of the neck, on the contrary, are very distinct ; nevertheless, the attachments which they necessarily have be- neath the back and the ribs, instead of on the outer side, as is usually the case, renders it exceedingly difficult to compare them with those of other animals. Still some points of relationship may be traced between them and those of birds. Thus, in the horizontal por- tion of the neck, close to the bones, are the intertransversales, separable, as in birds, in- to two sets of fasciculi, one upon the dorsal, and the other upon the ventral aspect. These are the infcrtransvcrsarii colli and ti'ansversarii colli obliqiii of Bojanus. There is, moreover, in this horizontal part of the neck, the great transversalis, composed, as in birds, of two fascicles inserted into the transverse process of each vertebra, and de- rived from the transverse processes of the two preceding vertebrae. The anterior longus colli arises from the first dorsal vertebra ; it runs along all the ventral aspect of the curva- ture of the neck, receiving additional fibres from, and giving off' tendons to all. Another muscle, very similar in its dis- tribution to the longus colli posticus of birds, but slightly different in its insertion, arises from the carapax in front of the last vertebra of the neck, and gives off" fleshy fasciculi to four or five of the vertebrae that precede it, but it inserts them into the crests, which represent spinous apophyses ; moreover, there is no accessory nmscle as in birds. In one circumstance, however, there is a re- semblance, namely, its last fasciculus, which is very long ; those likewise to the head, where it is inserted into the upper aspect of the head, above the sjilenius : neverthe- less it is not digastric, as that of birds. The larger portion of this muscle is named by Bojanus the spinalis colli, and the slip which it gives off" to the head the splenius capitis : the tortoise has also a small complexus, which is derived only from the transverse apophyses of two or three of the anterior cervical vertebrae, and runs to the head, ex- ternal to the splenius and to the fasciculus above mentioned. This splenius, which does not exist in birds, arises in the land and fresh- water tortoises from the dorsal crests of the fourth, fifth, and sixth vertebrae, and runs to the head, where, dividing into two portions, it covers the upper surface of the occiput : this is the biventer cervicis of Bojanus. In the turtles its divisions are more widely separated ; the internal arises only from the most anterior vertebrae, whilst the external is derived from beneath the anterior edge of the * Cu^•ier, Lemons d'Anatomie Coniparee, la^t edi* tion. T 274 REPTILIA. carapax ; this gives off a fasciculus to the atlas, which is the splenius colli. So far, even as regards the small mus- cles of the neck, the analogies are suffi- ciently satisfactory; but it is not so with the long muscles coming from the dorsal or lumbar portion of the spine, which are re- placed by others having a totally contrary Fig. 191. Myology of the European Tortoise. 1, temporal muscle ; 3, digastricus ; 13, mylohyoides ; 16, hyomaxillaris ; 21, transverse muscle, embracing the neck ; 40, obliquus abdominis ; 41, transversus abdominis ; 43, attrahens, and 44, retrahens, pelvis ; 53, sphincter cloacae ; 54, dilator cloacae ; 56, pectoralis major ; 57, serratus magnus ; 60 a and 60 b, del- toides ; 62, superscapularis, representing the supraspinatus and iiifraspinatus of other animals ; 65 a and 65 c, triceps brachii ; 66 a, 66 b, biceps brachii ; 68, palmaris ; 69, flexor sublimis ; 70, flexoris profundi tendines ultimi ; 71, pronator teres ; 73, ulnaris internus ; 76, radialis externus longus ; 78, supinator longus ; 82, extensor proprius digiti minimi ; 83, extensores quinque breves digitorum manus ; 84, abductor poUicis ; 87, lumbricales manus externi ; 88, flexores digitorum breves ; 91, iliacus intemus ; 94, glutaei pars; 97, triceps femoris abductor; 101, vastus intemus; 103, bicipitis cruris pars; 105 6, semimembranosis ; 106, sartorius ; 107, gracilis ; 108, extensoris coramimis digitorum tendo ; 109, tibialis anticus; 111, extensor brevis digitonun ; 112, extensor proprius hallucis ; 114 6, gastrocnemius; 117, extremi tendines flexores, plantarem inter et soleum atque flexorem longum digitorum; 118, flexores breves digitorum pedis ; 122, interossii digitorum pedis dorsales. (After Bojanus.') position. Of these, in the land tortoises, and in the fresh-water tortoises, the principal is a thin lamina attached within the carapax to the ribs of the fifth arid sixth dorsal vertebrae, and running together with its fellow of the opposite side obliquely forwards, and in the interval between the two lungs, on to the sides of the anterior or horizontal portion of the neck, where it is inserted by fascicuU to the transverse apophyses of the third, fourth, and fifth cervical vertebrae : it terminates by a long fasciculus, which is inserted beneath the head to the basilar bone. This muscle draws the neck and head backwards, and to one side ; this is the retrahens capitis of Bojanus. A little more forward, and beneath the articulation of the fourth and fifth dorsal vertebrie, there is a similar muscle, which might indeed be regarded as a portion of the preceding, and which goes to be inserted into the side of the sixth cervical vertebra: this REPTILIA. 275 draws the head and neck powerfidly back- wards ;-dt is the retrahens colli of Bojanus. In the opinion of Cuvier, the former of these two muscles corresponds in function to the sacro lumbalis, and to the transversalis ; the latter to the longissimus dorsi ; but modified in arrangement to suit the disposition of the skeleton. In the turtle they are reduced to a single fasciculus, which runs from the third dorsal vertebra to the basilar bone, performing the office of the rectus capitis anticus. There is a third still more singular muscle which runs along the spine, receiving fibres from all the vertebrae, and traversing the in- tervals left between the heads of the ribs and the carapax, and terminating in front upon the anterior surface of the eighth cervical ver- tebra, which it draws forward, and with it the posterior vertical portion of the neck : its position reminds us slightly of the spinalis dorsi, but its insertion is very different. A muscular expansion, composed of trans- verse fibres attached on each side to the sides of the vertebrae, envelojies all the lateral and inferior portion of the neck, including the trachea and the oesophagus, joining in front the mylohyoideus, and connecting itself posteriorly with the inner borders of the plastron : this is a cutaneous muscle, similar to that which envelopes the neck of birds. In the Chelonian reptiles, the muscles of the head cannot be designated by the same names as those of birds and mammalia, because the carapax gives origin to the greater number of them ; we must therefore content ourselves by indicating their attach- ments. Upon the posterior part of the neck we remark, first, at the anterior edge, to- wards the angle of its crescentic margin, a broad muscle which runs as far as the lateral and posterior parts of the head, where it is inserted : this will draw the head back- wards. 2d. Beneath, and from the middle of the anterior crescentic space, there arises another muscle, which is slender and round, and which, separating itself from its fellow of the op- posite side, so as to form a figure of V, runs to be inserted upon the external border of the preceding : its office is similar to that of the last. 3d. The analogue of the splenius capitis arises from the spinous processes of the third, fourth, and fifth vertebrae of the neck by distinct slips, and is inserted into the occipital arch : this is the elevator of the head. 4th. The analogue of the rectus anticus major arises from the inferior tubercles of the four cervical vertebrae which succeed the first, and is inserted fleshy into the basilar fossa beneath the condyle. 5th. The trachelomastoideus arises from the inferior tubercles of the second and of the third cervical vertebrae, by two thin aponeurotic tendons ; it is inserted thick and fleshy into the eminence which corresponds with the mastoid process : this muscle bends the head to one side. 6th. Lastly, at the upper part of the cervical portion of the spine is a short muscle, which runs from the lower border of the hole formed by the temporal fossas to the spinous apophyses of the first, second, and third cervical vertebrae. In front of the neck may be remarked the analogue of the sternomastoideus which arises from the strong aponeuroses which covers the humerus near its articulation with the scapula. Its inferior third only is visible when the skin is raised, the anterior two- thirds being covered by a transverse muscular expansion representing the mylohyoideus, and the platisma myoides. It is inserted underneath the apophysis that corresponds with the mastoid process. Its action will be to draw the head inwards, and slightly to elevate the shoulder. The rectus capitis anticus arises from the inferior spine of the third vertebra of the back, and is inserted by a thin tendon into the basilar process of the occipital bone. In the Chelonian reptiles the head is arti- culated with the atlas by means of a single condyle ; in the land-tortoises it is prolonged and divided into two ; in the turtles it pre- sents three articulating surfaces resembling the leaf of trefoil. As this tubercle penetrates very deeply into the corresponding cavity of the atlas, the lateral movements of the head must be extremely limited ; the other move- ments of the head in the Chelonians are those of protraction and retraction : these depend upon the flexion and extension of the neck. In the Trionyx, Nature has doubly provided against any lateral movement in the posterior region of the neck : first, the articulations of the last cervical vertebra with the first dorsal are disposed so as to form an angular hinge, the posterior articular apophyses of the cer- vical forming a hollow cylinder, whilst the anterior articulating process of the dorsal is likewise cylindrical ; secondly, the body of the eighth cervical terminates anteriorly in two condyles, which are received in corre- sponding cavities in the body of the seventh. In the jVlatamata, which, instead of bending its neck vertically, bends it by lateral flexion, the disposition of the articulations is entirely different. The body of the eighth cervical ver- tebra is compressed laterally, and rounded at each end ; that of the seventh, on the con- trary, is excavated at both extremities ; that of the sixth rounded posteriorly, and hollowed in front ; the fifth rounded at both ends ; and the others, as usual, concave posteriorly and convex before. It results from this arrangement, combined with the disposition of the articular apo- physes, that the neck is capable of a double lateral curvature. Muscles of the Shoulder. — These muscles in the Chelonian reptiles difi^er considerably from those of other vertebrate animals : they are four in number. The first is attached beneath the edge of the carapax between the two ribs, and the pieces usually regarded as sternal ribs, from the second to the fifth. It is very thin, and T 2 276 REPTILIA. Fur. 192. 3IyQhgy of the Tortoise. 1, temporaKs ; 2, pterygoideus ; 3, digastricus maxillae ; 14, omohyoideus ; 16, hyomaxillaris ; 17, genioglossus ; 18, hyoglossus ; 22, sternomastoideus ; 26, trachelomastcideus ; 27, retrahens capitis collique ; 28, longus colli; 47, extensor Cauda?; 48, flexor caudte lateralis; 49, flexor caudte inferior ; 58, latissimus dorsi ; 59, subcla\'ius ; 64, subscapularis ; 65a, 65c, triceps brachii ; 70, flexor profimdis ; 73, ulnaris inteinus ; 74, ulnaris externus ; 76, radialis externus lougiis ; 78, supinator longus; 79, supinator bre-\-is ; 83, extensores quinque breves digitorum manus ; 85, abductor digiti minimi ; 88, flexores breves digitorum quatuor ; 91, iliacus internus ; 94, glutjeus ; 97, triceps abductor femoris ; 98, pectineus ; 100, vastus externus ; 101, vastus intemus ; 102, crureus ; 103, biceps cruris ; 104, semitendinosus ; 108, extensoris communis digitorum pedis pars; 111, extensoris brevis digitorum pars; 112, extensoris proprii hallucis pars; 116, soleus ; 117, flexor longus digitorum pedis; 119, tibialis posticus ; 120, interosseus cruris ; 123, interossei digitorum pedis plantares. runs to the external border of the coracoid bone. From these insertions it cannot but be regarded as the serratus antic us (costo coracoidien) (^/?g. 191. ,57). 2d. The elevator of the scapula is inserted at the middle internal portion of the scapula, and derives its origin by seven fleshy slips from the transverse apophyses of the seven last vertebras of the neck. 3d. Another small elongated muscle is at- tached beneath the carapax, near the sternal extremity of the first rib, and is inserted upon the dorsal extremity of the first bone of the shoulder : this is probably all that remains of the serratus magnus, for it must not be forgotten that here the muscles, as well as the bones, are in an inverse position. The above description is taken from the turtle ; in the land-tortoises the second muscle is very strong, and occupies all the length of the border of the scapula. Bojanus considers it as representing the Scalenus. 4th. There is a thin muscle met with in the fresh-water tortoises, of which Bojanus makes no mention ; this is inserted upon the anterior margin of the acromion ; it runs along the side of the neck, but without any attachment to the bones ; it is lost in the general aponeurosis. If this be not regarded as a platysma, it can only represent the tra- pezius. In the emydes, vestiges of a dorsal cutaneous muscle are inserted into the apo- neurosis of the subscapularis. Muscles of the Ann. — In order to under- stand the arrangement of the muscles of the shoulder and arm in the Chelonian reptiles, it is necessary to bear in mind that their scapula is styliforra, that the acromion and the coracoid are singularly elongated, and that the entire scapula with the humerus are REPTILTA. 277 Fig. 193. 3Tyology of the Tortoise. 12, palpebralis, representing the orbicularis muscle of the eye ; 23, splenius capitis ; 24, biventer cervicis ; 33, transversalis cervicis ; 35, spinalis cenacis ; 40, obliquus abdominis ; 41, 41a, 41b, transversus abdominis ; 42, a muscle thought by Bojanus to be analogous to the diaphragm ; 45, adducens pelvim ; 46, abducens pelvim ; 47, extensor caudce ; 48, flexor caudae lateralis ; 49 — 51, flexores caudae, inferior, lumbalis et obturatorius ; 53, sphincter cloacte ; 58, latissimus dorsi ; 110, peroneus. The other muscles are indicated by the same letters as in the preceding figures. SO disposed that the coracoid bone, instead of ternal, is anterior; this arrangement, in fact, being anterior, as in mammalia, is internal, exists more or less in all oviparous verte- and that the acromion, instead of being ex- brata. Fig. 194. Myology of the Tortoise. 5, rectus oculi supei-ior; 8, rectus oculi externus; 11, suspensor oculi; 14, omohyoideus ; 16, hyo- maxillaris ; 18, hyoglossus ; 22, stemomastoideus ; 24, biventer cerv'icis ; 25, complexus ; 34, scalenus ; 37, transversarii colli obliqui. The other muscles as in preceding figures. The analogue of the great pectoral {fig. 191, 56) is composed of two superficial portions, one of which is attached to a ridge on the anterior part of the plastron, and goes to be inserted into the small tuberosity of humerus: the other is much more extensive ; it arises from a great portion of the internal surface of the plastron, and is likewise inserted by a flat- tened tendon into the lesser tuberosity of the humerus, but it is continued by an aponeu- rotic expansion, which spreads like a fan over the inferior surface of the arm, and even of the fore-arm : its tendon is united to that of the preceding. The analogue of the deltoid {fig. 191, 60 «, and 606) arises from the extremity of the acromion, and goes to be inserted upon the external surface of the small tuberosity of the humerus, uniting its tendon to that of the infra-spinalis. The latissimus dorsi {fig- 192. 58) arises from the lateral part of the carapax as far as the articulation of the second rib, and runs nearly vertically towards the humerus, joining its tendon with that of the teres major, to be implanted in a fossa situated at the base of the internal tuberosity. The supra-spinatus arises from the pos- terior aspect of the spine of the scapula, and runs to be inserted into the external tuberosity. In the turtles it is reinforced by a large muscle derived from the anterior edge and the superior siu^face of the ex- tremity of the coracoid. The infra- spinatus arises from the posterior border of the spine of the scapula, and runs to T 3 278 REPTILIA. oin its tendon to that of the deltoid. In the turtles it is prolonged over all the posterior 3Iyologi/ of the Tortoise. 2, pter\-goideus ; 4, dilator tubse : 29, rectus ca- pitis anterior longus; 30, rectus capitis anterior minor; 31, rectus capitis posterior major : 32, rectus capitis posterior minor ; 36, intertransversarii colli ; 37, transversarii colli obliqui ; 39. longissimus dorsi ; 42, diaphragmaticus. face of the acromion, and is inserted a little higher up than the deltoid. The subscapularis (Jig. 201. 61) is the strongest muscle of the arm ; it arises from all the posterior surface of the scapula, and from three-fourths of the superior face of the coracoid, and runs to attach itself broadly to all the anterior tace of the internal tube- rosity ; its coracoid portion describes nearly a quarter of a circle to arrive at its destination. Its action must be powerfully to rotate the arm at the same time that the scapular portion advances it forward. The teres major arises from the posterior edge of the scapula, and unites its tendon to that of the latissinius dorsi. In the turtles there is a teres minor, which arises from the anterior portion of the pos- terior border of the scapula, and runs to be inserted close to the deltoid. The coraco-brachialis consists of two por- tions, as in some mammalia, one of which, the larger, arises broadly from the inferior surface of the coracoid bone ; the other, much smaller, arises between the preceding and the biceps : both are inserted near the sub- scapularis into the internal tuberosity of the humerus. It will be seen from the above account that the muscles of the arm in the Chelonian reptiles are very similar to those of mam- malia, only their different portions are more widely separated on account of the great prolongation of the acromion, and of the coracoid. JMusdes of the Fore-arm. — The bones of the arm and the fore-arm not having undergone the same distortion as those of the shoulder, the muscles are less changed from the usual arrangement. The biceps alone coming from the coracoid bone, must necessarily follow its Fig. 196. Jli/olopt/ of the Tortoise^ 9, oliliquus oculi superior; 10, obliquus oculi inferior; 27, retrahens capitis collique; 52, flexor caudc ischiadicus. Other muscles indicated by same letters as in preceding figures. movements ; it, however, always arises from its anterior margin, and passes along the bicipital groove when that exists in the Che- lonians. It is only fleshy at its coracoidal extremity ; all the rest consists of a tendon. w hich runs along the humerus to be inserted into the radius. The brachialis internus occupies its usual situation, as also does the triceps brachii; the latter, however, is proj)ortionally small, and REPTILIA, 279 in the turtles appears to have no scapular origin. Fig. 197. ( Myology of the Tortoise 71, pronator teres (insertion of); 72, pronator quadratus ; 75, radlalis internus ; 88, flexores digi- torum breves ; 90, interossei digitorum manus in- temi. There is only one supinator*, which is in- serted into the wrist; it arises from the ex- ternal condyle, but in the turtles this muscle is wanting. Both the pronators of the fore- arm are present in the land-tortoise ; however, the pronator quadratus is very small, and situated close to the carpus. Muscles of the Hand. — The muscles of the Fig. 198. Myology of the Tortoise. 86, abductor digiti tertii, quarti et quiuti ; 90, interossei digitorum manus intemi. fingers are, in the turtle, few in number, their hand being so flattened out into the shape of a fin or oar as to require neither flexors nor extensors of the fingers; in these, therefore, the analogue of the extensor digitorum com- munis is confounded with the general apo- neurosis. The flexor communis is sliiihtly more distinct; and the interossei, the abduc- tors and adductors of the thumb and of the fifth finger exist, the latter serving to expand or to contract the oar. * Bojanus regards the muscle marked 79 {fg. 192) as a supinator brevis. In spite of the extreme shortness of the hand in the land-tortoises, the muscles are well developed, and the extensor communis, the extensor, and the long abductor of the thumb, the flexor sublimis, the flexor pro- fundus, the adductor of the thumb, and the abductors of the little finger, as well as the interossei, are met with. Muscles of the Pelvis. — In the tortoise the Myology of the Tortoise. a, glans penis ; 6, bulbus penis ; c, vein derived from ditto; 50, flexor caudae lumbalis; 51, flexor Cauda? obturatorius ; 52, flexor caudae ischiadicus ; 55, protrahens penis. muscle analogous to the quadratus lumborum spreads out beneath the carapax between the antepenultimate ribs: it is inserted into the ileum near the articulation of that bone with the sacrum, that articulation being in the Chelonians moveable. This mobility of the pelvis is aided by the analogue of the rectus abdominis, which, instead of spreading out beneath the belly, is attached under the posterior extremity of the plastron by two fleshy bellies, one in front and the other behind ; both run to be inserted into the anterior margin of the external ramus of the pubis. Muscles of the Thigh. — In the land and fresh-water tortoises, although the ossa ilii are very narrow, the muscles belonging to the thigh are of considerable thickness. The glutaeus maxiraus, which might almost be mistaken for a pyramidalis, is only attached to the ileum by a small proportion of its fibres, the remainder are derived from the transverse apophyses of the caudal vertebrae. The glutaeus medius and minimus, united together at their origin, constitute a mass which arises from all the external surface of the ileum, from its anterior border, slightly from its internal surface, and even from the inferior surface of the seventh rib : this muscle divides into two tendons, one of which, that of the glutaeus medius, is inserted into the trochanter ; the other, that of the glutaeus minimus, a little lower down into the body o. the femur. The obturator internus is a very strong muscle arising from the upper aspect of the internal ramus of the pubis, and winding around the ischium, as in mammalia, to be inserted into the great trochanter. The quadratus femoris exists, but neither gemelli nor pyramidalis are present. There is no psoas ; but the ihacus is strong, and arises from the upper part of the internal T 4 Fig. 199. 280 REPTILIA. surface of the pubis, confounding its anterior margin with that of the gkitceus medius. The obturator externus (adductor of Bojanus) arises by two portions, one coming from the pubis, the other from the ischium ; their two tendons unite to form a broad tendon, which is inserted into the two trochanters. The adductors of the thigh do not arise from the pubis, but from the ischiadic portion of the symphysis. A muscle, the analogy of which it is diffi- cult to recognise, arises from the upper sur- face of the pubis, and goes to be inserted by a strong tendon at the side of the iliacus (iliacus internus of Bojanus, surpubien of Cuvier). In the turtles there is no iliacus, and the suprapubic muscle divides into two fasciculi, the external of which goes to the knee, and joins the rectus of the thigh. Muscles of the Leg. — The muscles of the leg are more recognisable than those of the thigh. In the land-tortoises these muscles are the triceps ; the sartorius, which is divided into two portions ; the semimembranosus, which has a large accessory slip derived from the coccyx; the rectus anticus, which is situated slightly internally, has an origin from the ex- ternal ramus of the pubis, and is connected with the articular capsule of the knee joint ; the gracilis is confounded at its origin from the ischium with the adductors of the thigh, but it separates from them, and is inserted at some distance from the head of the tibia. In the turtles the muscles are not so thick as in the land-tortoises ; the advanced position of the pubis gives to the anterior rectus great force in extending the thigh and the leg, for it is inserted into the knee almost at a right angle. The biceps and the semimembranosus arise from the coccygeal region only. In the terrestrial tortoises the movements of the foot upon the leg, and of the different parts of the foot one upon the other, are very limited, and consequently the muscles which execute them are indistinct. There is but one peroneus, which is con- founded by one of its margins with the ex- tensor communis, and which is inserted into the OS calcis and into the cuboid. The gastrocnemius externus alone takes its origin from the femur ; the gastrocnemius internus arises from the tibia and joins itself to the solaeus. This latter is divided into three portions, one external, one median, the other internal. These muscles, in conjunction with the peronei and the long flexor of the toes, form beneath the foot a thick ten- dinous mass ; they extend the foot upon the leg, and flex the latter upon the thigh ; but it is next to impossible to distinguish the dif- ferent portions. The tibialis anticus is distinct. In the turtles which have the foot, like the hand, flattened into the shape of an oar, the gastrocnemii are disposed as in the land- tortoises, and the soleus is equally strong. There exists, moreover, a slender plantaris longus, which arises from the external tube- rosity of the femur by a long round tencfon, and which terminates in a broad expansion. Fig. 200. Myology of the Tortoise. (^After Bojanus.') 119, tibialis posticus ; 120, interosseus cruris ; 122, interossei digitorum pedis dorsales; 123, in- terossei digitorum pedis plantares. which is inserted partly into the os calcis, and partly into the plantar fascia. This muscle is from its position an adductor of the foot. The tibialis anticus preserves its ordinary re- lations ; but the tibialis posticus runs from without to within, and its tendon becomes lost in the plantar fascia. The toes of the Chelonians not having more flexibility than their fingers, the muscles of the foot are much confused. The extensor communis longus digitorum, as in all other reptiles, only reaches as far as the bones oi the metatarsus. The extensor brevis alone reaches to the phalanges of the toes. There is, however, a proper extensor for the great toe, which arises from the inferior extremity of the fibula, an abductor of the little toe, and interossei, which latter, as in mammaha, are both adductors and abductors. In the turtles the extensor communis spreads out as it approaches the toes, and forms a broad aponeurosis, which covers the whole foot. The extensor longus, and the abductor of Fig. 201. Myology of the Tortoise. {After Bojanus.) 117, teudous of the flexor longus digitorum ; 118, flexor brevis digitorum pedis. the inner toe, arise from the inferior extremity of the fibula, and are inserted into the meta- tarsal bone that supports this toe, as well as into the first and second phalanges. Another muscle, which also arises from the inferior extremity of the fibula, is in- serted into the whole length of the metatarsal bone of the fifth toe, and upon its first pha- lanx : it is both an extensor and an adductor. REPTILIA. 281 The flexor brevis digitorum gives off a slip to each of the three middle toes. Myology of Ophidian Reptiles. jMuscles of the Spine. — In serpents, as might be expected, the muscles of the spine are very completely developed, and easy to identify. The spinalis dorsi arises from the lateral surface of the spinous processes of the verte- brae, and likewise receives tendons of rein- forcement from the longissimus dorsi, which spread out and are lost upon its inferior sur- face ; this muscle divides itself internally into as many fasciculi as there are vertebrae, each fasciculus terminating in a very long tendon, which runs in an aponeurotic sheath to be inserted into the spinous process of the ver- tebra to which it is destined. The longissimus dorsi arises by fleshy fibres from the extremities of the articular apo- physes, which here perforin the office of transverse processes. These slips, after having become united with each other, give off two sets of tendons, one of which runs obHquely to assist in giving origin to the spinalis dorsi ; the others descend in like manner, and constitute the only tendons of origin of the sacro-lumbalis, so that this mus- cle cannot be said to have any direct insertion upon the vertebral column. The sacro-lumbalis arises from the tendons of the longissimus dorsi just described, and divides itself externally into slips, each of which is inserted by a slender tendon into the posterior edge of the upper third of one of the ribs. Under the spinalis dorsi is found the semi- spinalis (transverso-spinalis), and beneath this the interspinalis. On the inferior aspect of the vertebral column there is found a muscle in all respects analogous to the longus colli, except as re- gards its extent, and which might be called the transverso-spinahs inferior : this extends from the inferior spinous process of one vertebra to the transverse processes of the second and third succeeding vertebrae. All the above six muscles ex'st from the end of the tail as far as the head : their last fasciculi, viz. those inserted into the skull, although their arrangement is slightly altered, cannot be considered on that account as being distinct muscles. The sacro-lumbalis, more- over, on ariiving at the caudal region, is in- serted into the transverse processes of the caudal vertebrae, instead of into the ribs, so that as the tail becomes attenuated the-e muscles are blended together: neverthe- less, there are always vestiges of them per- ceptible. Muscles of the Ribs. — These are the trans- verso-costal muscles, arising from the trans- verse processes of each vertebra, and running to be inserted into the following rib, for about the superior fourth of its length. The great lateral costal muscles which cover the side of the trunk of the body, arise behind the insertions of the pre- ceding, each passing obliquely over four ribs, to which it gives off a few fibres, is inserted into the fifth behind that from which it takes its origin. Fig. 202. Lateral View of the Muscles which move the Bibs of the Boa Constrictor. AA, the straight muscles of the back; b, the first set of muscles, which arises from the trans- verse processes of each vertebra, and. is inserted into the rib behind it, close to its head ; c, the second set ; D D, the third set ; E, the fourth set ; F, the fifth set ; G G, short muscles which pass from carti- lage to cartilage ; H H, a set of oblique muscles, which pass from the anterior side of the bony ex- tremity of each rib to the posterior edge of each scutum ; 1 1, muscles which pass from the ribs, near their heads, obliquely backwards, to be inserted into the skin at the edge of each scutum ; k, muscles of the scuta. (^After Home. ) The great inferior costals take their origin below the preceding, and are inserted in the same manner, only their direction is more longitudinal, so that they occupy a smaller proportion of the length of the ribs. The smaller costal muscles are placed be- tween the two preceding sets, and pass from one rib to the next behind it. The intercostal muscles occupy their ordi- nary position, and, as usual, are arranged in two planes which decussate each other. In addition to the above, there exists in the interior of the thorax an inferior transverso- costal muscle; this arises from the angle of the tubercle to which the rib is attached, and running obliquely forwards, passing three ribs, is inserted into the fourth a little below the 282 REPTILIA. middle of its length. This muscle is described by Sir Everard Home* as being in the boa constrictor divided into two, an upper and a lower portion ; but in other species, although a slight line of demarcation may be detected, such a division is scarcely admissible. From the ribs of serpents muscular fasci- A71 internal lieu- of iht JImcles which move the Ribs in the Boa Co7istrictor. A A, the muscles which pass from cartilage to cartilage of the different ribs ; b B, a set of muscles ■which pass from the point of each rib, over two ribs to the middle of the third ; c, a similar set of muscles continued from the opposite side of the rib, passing over three ribs to the body of the vertebra ; DD, the abdominal muscles which arise from the anterior edge of each rib, and pass to the linea alba ; E, the linea alba ; f f, the terminations of the oblique muscles which pass from the bony ex- tremities of the ribs to the edges of the scuta ; G G, the muscles of the scuta, consisting of two sets, which decussate each other. culi are given off, which go to be inserted into the skin : some of these arise from the same point as the great lateral costals. Their course is from before backwards, and from above downwards as they run, spreading out like a fan, to be attached to the sides of the ventral scuta. The others arise from the lower part of the rib, opposite the point of attachment of the long inferior costal muscle ; these run from behind forwards to be fixed to the angle of a ventral scutum, about * Lectures on Comp. An at., vol. i. three ribs off. The ribs, moreover, give at- tachment to a visceral muscle. In serpents there is only one muscle pro- per to the head, which seems to represent the complexus ; this arises from the articular apophyses of the five or six anterior vertebrge, and is inserted into the mastoid bone. The transverso-spinalis is continued as far forwards as the occipital bone, and thus re- places the recti capitis. The movements of the head upon the spine are, indeed, very limited in the ophidia. The body of the atlas presents three articular facets arranged after the manner of the leaves of a trefoil, which are attached to the occiput beneath the foramen magnum, so that the head is not more moveable upon the atlas than the other vertebra upon each other. The muscles of the head of serpents have been carefully dissected by M. Duges*, M. Duvernoyf, Brandt and Ratzburgj, and others. The following brief account of this part of their myology, taken from the last edition of Cuvier's Anatomie Comparee, must, however, suffice for our present purpose. The true serpents have the zygomatic (tympanic) bones {fg. 205, 7) moveable, and suspended from another bone analogous to the mastoid (6), which is attached to the cranium by means of muscles and ligaments that allow of considerable mobility : the two sides of the lower jaw, moreover, are but loosely connected with each other, and the superior maxillary bones (2) are only united to the inter-maxillary bones (1) by ligaments, so that they can be separated to a greater or less extent ; a circumstance which confers upon these reptiles the faculty of dilating their rictus, thus enabling them to swallow animals whole which could not otherwise bv possibility pass into their mouths. In ad- dition to the above arrangement, the maxil- laries (2), the palatine bones, and the ossa pterygoidea (3, 4), are more or less moveable beneath the cranium, so that the animal can raise or depress the palatine or pterygoid arches, as well as those formed by the upper maxilla, and also can separate them, or ap- proximate them to each other. The muscles subservient to the movements of the jaws are the following : — All serpents whose mandibular arches are moveable, as above described, have generally three distinct temporal muscles, one anterior, one median, and the other posterior. The antej^ior temporal {^jig. 204-, e) is at- tached superiorly behind the orbit, and de- scending downwards and backwards, Nsinds round the commissure of the lips, and turning forward again (e'), is inserted into the lower jaw, very considerably in front of the angle of the mouth. The middle temporal {fig. 20-t, i.) is partly covered by the anterior temporal, it descends nearly verticcdly from the middle and ujiper * Ann. des Sc. Nat, torn. xii. 1827. p. 378. t Ann. des Sc. Xat. tom. xxvi. 1832. p. 113. X Medezinische Zoologie, 4to. 1829 REPTILIA. 283 portion of the temporal fossa, until it meets the jaw into which it is inserted, either separately or conjointly with the anterior temporal. The posterior (emjjoral (/), which is al- ways distinct from the two others, descends from the very posterior part of the temi)oral fossa, along the zygomatic bone (tj/mpmiic) {fg. 205, 7), to the lower, into which it is inserted behind the two others. The mouth is opened by means of a muscle Fig. 20 i. Tlie Muscles of the Head of the Rattlesnake. a a, poison gland and its excretory duct ; e, anterior temporal muscle; /, posterior temporal muscle ; g, digastricus ; h, external pterygoid muscle ; /, middle temporal muscle ; q, articulo- maxillarv ligament which joins the aponeurotic capsule of the poison gland ; r, the cer\ical angular muscle ; t, vertebro-mandibular muscle ; u, costo- mandibular muscle, i^fter Duvernoi/.^ analogous to the digastric (g), which arises from the whole length of the posterior aspect of the zygomatic {ti/mjyanic) bone, and ter- minates on each side at the angle of the jaw beyond its articulation. There is likewise a cutaneous muscle which powerfully contributes to depress the lower jaw, something like the my- oides ; this has been named the costo-mandibu- lar'u (u). This, moreover, is assisted by a strong fasciculus (/), derived from the spinous processes of the vertebrae immediately be- hind the cranium, which has been distin- guished by the name of the vertebro-mandi- bularis. Two sets of muscles are appropriated to the movement of the zygomatic {li/mpanic) bone which supports the lower jaw : of these one arises on each side from the back of the occipital region, and is inserted into the lower portion of the bone above referred to. The other [Jig. 205, m) is cizi/gos, and has been named by M. Duges siib-occipito articu- laris, its fibres run across beneath the base of the skull, from the articulation of the lower jaw on the one side, to that on the other. The former pair of muscles will draw the branches of the lower jaw upwards and inwards, the azygos muscle will move them inwards and downwards. The anterior extremities of the lower jaw can be approximated by a little muscle {fig. 206, v), which passes transversely from one to the other. This muscle, which is tendinous Fig. 205. 3Iuscles of the Pterygo-Palatine Apparatus of the Rattlesnake (Crotalus durissus). (After Du- vernot/,) 1, mtermaxillarv and nasal bones ; 2, 2, superior maxillary bones 3, external pterygoid bone ; 4, internal pterygoid bone ; 5, palatine arch ; 6, mas- toid bone; /, the tympanic bone; a, capsule of the poison-gland ; a', duct of ditto; h,h, external pterygoid muscle; k, internal pterj-goid muscle; /, I, spheno-pter\-goid muscle ; m, the suboccipito- articular muscle'(of Duges) ; n, the spheno-palatine muscle ; o, the spheno-vomerine muscle. along the mesian line, is analogous to the mi/lo-hyoideus; it likewise gives off a slip v\ which is attached to the skin. The muscles belonging to the maxillary and palatine bones are, — The external pterygoid {Jig. 204, h), which, arising from each jaw, runs directly forward as far as the maxillary extremity of the exter- nal pterygoid bone, which it draws powerfully backwards. In venon^ous serpents with an- terior poison fangs, which have the external pterygoids very long, and the maxillary bones very short, this muscle is very strong, arising by aponeurotic fibres, from the capsule which encloses the articulation of the lower jaw, whence it runs forwards towards the pouch in which the venomous teeth are lodged, upon which it is partially spread out ; its principal attachment, however, is to the posterior apo- physis of the superior-maxillary bone, into which it is inserted by a distinct tendon. The use of this muscle is evidently to carry back- wards the venomous fangs when they are to be laid flat, and to incline them towards the pa- late, a position that they retain while in a state 284 REPTILIA. of repose, in which condition it covers them by drawing the inclosing pouch over them. The internal 2Jtcrijgoid (k), shorter and smaller than the external, runs from the alar bone to the posterior part of the lower jaw, which it consequently draws forwards. The s2)/ieno-j)teri/goid (I), which has no ana- logue in other vertebrata, arises from the mesial portion of the base of the cranium, and runs outwards and backwards to be at- tached to the inner surface of the pterygoid plate, which it can thus drag forwards a»ul inwards so as to cause the protraction of the superior maxillary bone, thus raising the venom fangs ; it will likewise narrow the mouth by causing the approximation of the two internal arches. It is assisted in its ac- tion by a muscle, which Cuvier regards as a dismemberment of the temporal, the post-or- hilo-palatine, which runs from the temporal fossa behind the orbit to the palatine arch. The 8j)heno-j>alatine {fig. 205, n) antagonises the two last ; it extends from all the length of the palatine arch to the mesial line of the base of the cranium ; its direction crossing that of the preceding muscle, above which it is placed. i3y its contraction it brings back- wards the entire upper jaw, approximating at the same time the branches that form it. Two small muscles {fig. 205, o) advance fx-om beneath the sphenoid, and run close to each other to be inserted by a slender tendon into the vomer. These are the spheno -vomerine muscles of Duges, for which it would be dif- ficult to find analogues. These muscles de- press the muzzle. In all the true serpents the tongue is en- closed in a membranous sheath, to be de- scribed hereafter ; and the os hyoides, which in the ophidia has no connexion with the larynx, consists of two simple cartilaginous stems {fig. 206, b,) running parallel to each other, which bend forwards underneath the sheath of the tongue, where they unite to form a sort of arch of almost membranous consis- tency. Corresponding with this simple form of the OS hyoides ; the hyoid system of muscles is very simple. The mylo-hyoideus, above described as being an adductorof thetwo divisions of the lower jaw, has some of its fibres confounded with those of the costo- mandibular muscles {fiigs. 204<. 206, %i\ which, coming from the anterior ribs, is attached to the lower margin of the inferior maxilla. Its central fascicuU are adherent to the rami of the OS hyoides, and more especially to the membranous arch which they form in front. They can therefore draw it either forwards or backwards, accordingly as it is the maxillary or the costal portion which contracts; and thus these fasciculi hold the place of both sterno-hyoidei and genio-hyoidei. In ser- pents, therefore, there are no muscles exclu- sively appropriated to the os hyoides. The tongue of serpents is slender, cylindri- cal, and forked at its extremity. It is lodged in a membranous sheath, the opening of which is situated near the anterior part of the mouth, and the animal can protrude it from its month to nearly its whole length, using it as an in- strument of touch, apparently comparable in Fio, 206. lluscles of the Throat of the Rattlesnake {Crotalus durissus). A, retractor muscles of the tongue (Hyo-vagi- niens) ; b, cornua of the os-Hyoides ; h, external pterygoid ; u, u, u, u, costo-mandibular muscles ; V, V, anterior adductor muscle of the rami of the lower jaw ; V, v', portion of the preceding connected with the skin of the throat ; .r, posterior adductor of the rami of the lower jaw ; y, a muscle running from the symphysis of the lower jaw to the sides of the trachea (genio-trachien) ; z, geno-vaginalis, representing the genio-glossi ; z', z", external and internal origins of ditto. some respects to the antennae of insects. The muscles by the agency of which it is pro- truded, are the gemo-vogimtle.s {fig. 206, z), re- presenting the genio-glossi. These arise by two fasciculi, of which the internal and small- est {z^) arises from the tendinous median portion of the adductor of the inferior maxillee {v); whilst the external (2''), which is the stroniicst, takes its origin from the ex- tremity of the lower jaw itself : these two portions unite and form a narrow^ band, which becomes applied to the sides of the sheath of the tongue, along which it is continued back- wards to its extremity. The retractors of the tongue {fig. 206, a) are analogous to the hyo-glossi ; they arise around the extremities of the rami of the os hyoides, and running forwards conjointly, enter the sheath of the tongue, and its proper investing membrane ; so that they constitute the ent've REPTILIA. 285 substance of that organ. The flexibility of the tongue seems to depend entirely upon the different muscular fasciculi of which these muscles are composed, having the power oi contracting separately, some being longer or shorter than others, accordingly as they ter- minate successively in the proper membrane of the tongue to which they are attached ; for there seem to be no transverse or oblique fibres constituting intrinsic lingual muscles. The mechanism by which the Cobra de Capello, when irritated and ready to seize its prey, expands the skin of the neck, giving it the appearance from which the snake takes its name, consists entirely of muscles, acting upon the ribs and external skin of the animal. From the rounded form of the hood, the skin has the appearance of being inflated ; but the most careful examination does not discover any communication between the trachea or the lungs, and the cellular membrane under the skin. In this snake, the ribs nearest the head, to the number of twenty on each side, have a different shape from the rest ; instead of bend- ing equally with the other ribs towards the belly, they go out in a lateral direction, having only a slight curvature, and when depressed, lie upon the side of the spine, on one another. In the extended state of the ribs, the skin of the back is brought over them, forming the hood ; and in their depressed state the hood disappears. The ribs are raised by four sets of muscles : one set from the spine to the upper edge of each rib ; a second set from the ribs above, passing over two ribs to the third rib below ; another set have their origins from the rib above, pass over one rib, and are inserted into the second below ; and a fourth set pass from rib to rib. The combined effect of these four sets of muscles raises and extends the ribs. The skin of the back is brought forwards on the neck, by a set of very large mus- cles, going off from each of the first twenty ribs on each side, a quarter of an inch from their head, by a tendinous origin, which soon becomes fleshy; the longest of these muscles are two inches long. They are inserted into the skin, and, when the ribs have been first extended, have the power of bringing the skin forwards to a great extent. Myology of Salamander {Salamandra tev restris). In-order to complete our survey of the myology of the reptilia, it has been deemed advisable to introduce in this place a brief sketch of the muscular system of the amphibia, which is obviously arranged upon the same plan as that of the quadruped reptiles pro- perly so called, and from its comparatively em- bryo condition is a subject of much interest.* Muscles of the Head. — The movements of the eye are effected in the usual manner by means of the four recti and two oblique mus- cles, the disposition of which is similar to what exists in reptilia generally. The movements of the jaw subservient to mastication, are performed by the agency of * See the article Amphibia. five muscles. Of these the first is a long muscular slip (fig. 207, 1.) that takes, its origin from the arch and spine of the first vertebra of the neck, and which, together with a broad triangular muscle (2), corresponding to the tem- poralis, that arises from the lateral region of the os-frontis and the parietal bones, is in- serted in front of the os quadratum into the upper margin of the lower jaw. A third muscle (3J, analogous to the masseter, arises at the upper extremity of the os quad- ratum towards its anterior part, and extends to the external surface. The three preced- ing muscles serve to close the jaws ; they are antagonised by a short muscle (4) de- rived from the quadrate and temporal bones ; whose attachment to the lower jaw is placed behind the centre of motion of the articulation of the jaw, and consequently its effect will be to open the lower jaw. Lastly, there is an external pterygoid mus- cle, provided for the lateral movements of the inferior maxilla. Muscles of the Trunk. — Running along the whole length of the back ihere is the broad lateral nmscle (fig. 207, .5), which like- wise forms the principal part of the lateral walls of the abdomen. This muscle forcibly reminds us of the great lateral masses of muscle which form the principal part of the body of fishes, and, in like manner, it is divided by tendinous intersections into as many por- tions as there are vertebr£e in the spine. Its commencement may be traced as far forwards as the occipital quadrate and temporal bones : it likewise has points of origin from the spinous and transverse processes of the whole vertebral column. These two lateral masses are separated above by a deep furrow (o a), which is filled up with a series of cutaneous glands peculiar to these animals. The dorsal portion is with difficulty separated into an upper and lower stratum, of which the upper and more external may be compared to the sacro-lumbalis, while the lower and broader one seems to represent the longiasimus dorsi. The cephalic extremity, having numerous points of attachment in the neck, and likewise the occipital region of the skull, forms several muscular bundles, more or less distinct from each other, which represent the muscles of the neck. The representative of the external oblique muscle of the abdomen (6), is here evi- dently merely a continuation of the great lateral muscle above described. In this re- gion, however, it attaches itself more particu- larly to the rudiments of the ribs and to the contiguous transverse process of the vertebra, extending from the second vertebra of the neck as far back as the pelvis ; inferiorly, it is connected with its fellow of the opposite side by a tendinous interlacement, represent- ing the linea alba. The internal oblique muscle of the abdomen is represented by the inner layer of the pre- ceding. By the partial separation of these two muscular layers, a sheath is formed w hich partially encloses the Pubo-hyoideus. 286 REPTILIA. The last named muscle {Shamziingenhein- muskcl) (Jig. 208, 7) arises partly from the os- Fig. 207. Muscles of Salamander tei-restris. pubis and partly from the outer border of the Y-shaped pelvic cartilage, whence it runs forward along the whole length of the abdo- men, enclosed in a sheath, formed between the internal and external oblique muscles of the abdomen as far as the throat, wdiere it is inserted into the middle cornea of the os- hyoides. The rectus abdominis (fg. 208, 8) takes its origin entirely from the Y-shaped pelvic car- tilage, and, first attaching itself to the trian- gular lower rudiment of the sternum, over which it passes, it becomes again connected with the upper transverse piece of the ster- num, from whence it sends a slip forwards to be inserted into the centre of the lower jaw : this last portion represents the genio-h3oi- deus. In its course, this muscle is divided by several tendinous intersections. It is, more- over, attached wnth some firmness to the pericardium, in the neighbourhood of which it gives off two additional slips of muscle, one of which passes obliquel}' outwards to join the pubo-hyoid ; the other (10) runs to be inserted into the scapula, becoming like- wise connected w^ith the scapulo-humeral articulation. The mylo-hyoideus {Jig. 208, 11) fills up the entire space betwen the arches of the lower jaw, from the angle of which, likewise, arise two cutaneous muscles {Jig. 207, 12) and {Jig. 208, 13), one of which extends into the skin of the inferior and anterior region of the neck, whilst the other mounts backwards and out- wards to be similarly inserted into the skin upon the sides of the cervical region. A muscle (^g. 208, 14) passes from the lower jaw near its symphasis, to be inserted into the extremity of the anterior cornu of the os- hyoides ; whilst a second slip (15) passes from the anterior to the central cornu of the latter bone. Muscles of the Extremities. — The pectoralis major {Jig. 208, 16) consists of two portions, one of which, 16 c, represents the clavicular portion in the human subject ; it entirely covers the lower surface of the shovel-shaped clavicle, so that it seems to form a distinct muscle. The following muscles are immediately re- cognisable from their position : The latissi- mus-dorsi(jfg.207, 1 1) ; the levatores-scapulas {fg. 207, 18 and 19); a muscle (20), the office of which is to draw the shoulder forwards. This muscle is derived from the sides of the occiput and anterior cervical vertebra, and extends to be inserted into the shoulder-blade near its articulation. The serratus magnus anticus {Jig. 208, 21) consists of only two small slips derived from the transverse processes of the second and third vertebras of the neck, and connected with the great lateral muscle of the trunk. The shoulder likewise possesses a muscle (22) that represents both the supra and infra spinatus, and a subscapularis occupying its usual position. The muscles of the humeral region are the representative of the biceps, and brachialis REPTILIA. 287 intemiis(j%.208,23), and the triceps extensor of the fore-arm. Fig. 208. 3Iuscles of Salamander terrestris. On the fore-arm may be distinguished the flexor carpi radiaUs (25), the flexor carpi ulnaris {Jig. 207, 26), the extensor carpi ulnaris (27), the extensor carpi radiaUs (fg. 208, 28), a flexor communis digitorum (29), and an extensor communis digitorum (30). Muscles of the hinder Extremiti/. — The thick flexor of the thigh (fg. 207, 31), repre- senting the iliacLis internus, arises broadly from the whole inner surface of the os ilei passes over the os pubis, and is inserted into the femur below its middle. The long ex- tensor and adductor of the thigh (32) arises from the third and fourth caudal vertebrae, and is inserted into the posterior aspect of the femur about its middle. The long abductor of the leg (fig. 207, 33) arises from the external surface of the os ilei, and is inserted into the tibia about its lower third. The anterior abductor of the thigh {^gs. 207 and 208, 34) arises from the anterior and internal surface of the os ilei, and is inserted into a broad tendinous expansion that covers the knee-joint. The thin flexor of the leg ( fg. 208, 36) arises from the inferior lateral surface of the os ilei, and is inserted into the outer part of the hea(l of the tibia. A long muscular slip (figs. 201 and 208, 37) arises from the transverse processes of the third and fourth vertebrae of the tail, and is inserted into the back of the thigh bone. The chief muscle of the sole of the foot (^38) arises from the side of the sacrum, and is inserted into the thick fascia of the sole. The other muscles of the foot are an extensor and abductor of the tarsus (39), which arises from the upper end of the tibia, and is inserted into the outer surface of the tarsal bone. An extensor longus digitorum pedis (40) arising from the fascia of the knee, and the anterior surface of the ligaments of that joint. This furnishes a tendon to each of the five toes. The flexor longus digitorum (41) , arising from the upper extremity of the tibia, and dividing into five tendons inserted into the last joints of the toes. A short ex- tensor arises from the entire anterior surface of the bones of the tarsus : its tendons unite with those of the long extensor. The short flexor arises from the ankle joint, and giving off* fleshy fibres to the tendons of the long flexor. There is likewise a special extensor and abductor of the great toe, and a similar one appropriated to the little toe. Both these arise from the ligaments of the tarsus. Ex- ternal and internal interossei muscles are likewise present. The other muscles represented in the atl- joining figures are the sphincter ani (42), and a flexor of the tail (43), derived from the transverse processes of the caudal vertebrae. The Teeth. — The dental apparatus of the Eeptilia is so widely different in its construc- tion in the different orders and even genera of this class of animals, that no general description of it is possible. We shall therefore quote Professor Owen's * account of the various ar- rangements adopted in the principal groups into ■which they have been divided by naturalists. In the Deirodon scaber, the inferior spinous processes of certain of the cervical vertebrae are unusually prolonged, and penetrate the * Owen's Odontography, page 179, et seq. 288 REPTILIA. coats of the oesophagus : their extremities, which are thus introduced into the aUmentar}^ canal, are coated with a layer of hard dentine, and form substitutes for the teeth, which, if not always entirely absent, are merely ru- dimental in the ordinary situations in the mouth. In the tortoises and turtles the jaws are covered, as is well known, by a sheath of horn, which in some species is of con>iderable thickness, and very dense ; its working sur- face is trenchant in the carnivorous species, but variously sculptured and adapted for both cutting and bruising in the vegetable feeders. The development of the continuous horny maxillary sheath commences, as in the parrot tribe, from a series of distinct papillae, which sink into alveolar cavities, regularly arranged (in Trionyx) along the margin of the upper and lower jaw-bones. These alveoli are indi- cated by the persistence of vascular canals long after the originally separate tooth-like cones have become confluent and the horny sheath completed. The teeth of the dentigerous Saurian and Ophidian reptiles are, for the most part, simple, and adapted for seizing and holding, but not for dividing or masticating their food. In no reptile are the teeth reduced to so small a number as in certain mammals and fishes, nor are they ever so numerous as in many of the latter class. Some species of Monitor ( rara/na) with sixteen teeth in the upper and fourteen in the lower jaw, afford examples of the smallest number in the present class. It is rarely that the number of teeth is fixed and determinate in any reptile so as to be characteristic of the species. The teeth may be present on the jaws only, as in the Crocodiles and many Lizards; or upon the jaws, and roof of the mouth, and here either upon the pterygoid bones, as in the Iguana, or upon both palatine and ptery- goid bones, as in most serpents. As a general rule, the teeth of reptiles are anchy- losed to the bone which supports them. When they continue distinct, they may be lodged either in a continuous groove, as in the extinct Ichthyosaur, or in separate sockets, as in the Crocodilians. The base of the tooth is anchylosed to the walls of a mode- rately deep socket, in the extinct Megalosaur and Thecodon. In most Ophidians, and in the Geckos, Aganuan-s, and Varanians, the base of the tooth is imbedded in a shallow socket, and confluent therewith. In the Scincoidians, Safe-guards (Tejus), in most Iguanians, in the Chameleons, and most other Lacertian reptiles, the tooth is anchylosed by an oblique surface extending from the base more or less upon the outer side of the crown to an external alveolar plate of bone, the inner alveolar plate not being developed. The lizards which have their teeth thus attached to the side of the jaw are termed Pleurodonts. In a few Iguanians, as the Istiures, the teeth appear to be soldered to the margins of the jaws: these have been termed Acrodonts. In some extinct La- certians, as the Mososaur and Leiodon, the tooth is fixed upon a raised conical process of bone. The completion of a tooth is soon followed by preparation for its remo%-al and succession. The facility of developing new tooth germs seems to be unhmited in the present class, and the phenomena of dental decadence and replacement are manifested at every period of life. The number of teeth is generally the same in each successive series, and the difference of size presented by the teeth of different and distinct series is consi- derable. The new germ is always developed, in the first instance, at the side of the base of the old tooth, never in the cavity of the base : the crocodiles form no exception to this rule. The poison fangs of serpents succeed each other from behind forwards ; in almost every other instance, the germ of the successional tooth is developed at the inner side of the base of its predecessor. As the tooth acquires hardness and size, it presses against the base of the contiguous attached tooth, causes a progressive absorp- tion of that part, and finally undermines, dis- places, and occupies the position of its predecessor. In the crocodile the tooth-germ is deve- loped from the vascular membrane covering the base of the internal wall of the socket. It is soon invested by a capsule, and by its pressure causes the formation of a shallow recess, or secondary alveolus, in the contiguous bone. In this alveolus, however, it never becomes inclosed like the successional teeth in most mammalia ; for, exerting equal pres- sure against the fang of the contiguous tooth, which, from being incompletely formed, has a wide pulp cavity with very thin walls, the nascent tooth soon penetrates that cavity, and quits the recess in the alveolar plate, in which it was originally situated. Thus the stage of development corresponding with the eruption of the tooth in the mammalia is im- mediately followed by the inclusion of the new tooth in the pulp cavity of its prede- cessor. The rapid succession of tooth germs, which stamps the impress of decay upon their predecessors often before the growth of these is completed, though common to many rep- tiles, is most strikingly manifested in the crocodiles, in which three and sometimes four generations of teeth, sheathed one within the other, are contained in the same socket. The order Ophidia, as it is characterised in the system of Cuvier, requires to be divided into two sections, according to the nature of the food, and the consequent modification of the jaws and teeth. Certain species, which subsist on worms, insects, and other small invertebrate animals, have the tympanic pedi- cle of the lower jaw immediately and im- moveably articulated to the walls of the cranium. The lateral branches of the lower REPTILIA. 289 jaw are fixed together at the symphysis, and are opposed by the usual vertical movement to a similarly complete maxillary arch above : these belong to the genera Amphisboena and Anguis of Linnaeus. The rest of the Ophi- dians (true serpents), which form the typical members, and by far the greatest proportion of the order, [)rey upon living animals of fre- quently much greater diameter than their own ; and the maxillary apparatus is conformably and peculiarly modified to permit of the requisite distention of the soft parts sur- rounding the mouth, and the transmission of their prey to the digestive cavity. The two superior maxillary bones have their anterior extremities joined by an elastic and yielding fibrous tissue, with the small and single intermaxillary bone ; the symphysial extremities of the lower maxillary rami are connected together by a similar tissue, allowing of a still wider lateral separation. The op- posite or posterior extremity of each ramus is articulated to a long and moveable vertical pedicle, formed by the tympanic or quadrate bone, which is itself attached to the extremity of a horizontal pedicle formed by the mastoid bone, so connected as also to allow of a certain yielding movement upon the cranium. The palatine and pterygoid {d) bones have similar loose and moveable articulations, and concur with the other dentigerous bones of the mouth in yielding to the pressure of the large bodies with which the teeth may have grappled. ^^'ith the exception of the Deirodon scaber and some congeneric species, in which the teeth of the ordinary bones of the mouth are so minute as to have been deemed wanting, the maxillary and premandibular in all true Ophi- dians are formidably armed with sharp- pointed teeth ; there is on each side the palate a row of similar teeth supported by the palatine and pterygoid bones. In the great Pythons, and some species of Boa, the intermaxillary bone also supports teeth. All the teeth, -whatever be their position, present a simple conical form ; the cone being long, slender, and terminated by an acute apex; and the tooih is either straight, or more commonly bent a Uttle beyond the ha>e, or simply recurved, or with a slight sigmoid inflection. The teeth are thus adapted for piercing, tearing, and holding, and not for dividing or bruising. In some species, certain teeth are traversed by a longitudinal groove for conveying an acrid saliva into the wounds which they inflict : in others, two or more teeth are longitudinally perforated for trans- mitting venom ; such teeth are called poison fangs, and are always confined to the superior maxillaries, and are generally placed near the anterior extremity of those bones. In the genus Deirodon the teeth of the ordinary bones of the mouth are so small as to be scarcely perceptible ; and they appear to be soon lost, so that it has been described as edentulous. An acquaintance with the habits and food of this species has shown how ad- mirably this apparent defect is adapted to its VOL. IV. well-being. Its business is to restrain the undue increase of the smaller birds by de- vouring their • eggs. Now if the teeth had existed of the ordinary form and propor- tions in the maxillary and palatal regions, the egg would have been broken as soon as it was sei/ed, and much of its nutritious contents would have escaped from the lip- less mouth of the snake in the act of de- glutition ; but, owing to the almo>t eden- tulous state of the jaws, the egg glides along the expanded opening unbroken ; and it is not until it has reached the gullet, and the closed mouth prevents any escape of the nutritious matter, that the shell is exposed to instruments adapted for its perforation. These instruments consist of the inferior spinous processes of the seven or eight pos- terior cervical vertebrae, the extremities of which are capped by a layer of hard cement, and penetrate the dorsal parietes of the oesophagus : they may be readily seen, even in very young subjects, in the interior of that tube, in which their points are directed backwards. The shell being sawed open longitudinally by these vertebral teeth, the egg is crushed by the contractions of the gullet, and is carried to the stomach, where the shell is no doubt soon dissolved by the acid gastric juice. ' In the Boa Constrictor the teeth are-^lei^der, conical, suddenly bent backwards antl jn- wards above their base of attachment, ?kyith the crown straight curved, as in the po**^r;or teeth. The intermaxillary boiie supports four small teeth ; each superior maxillary bone has eight much larger ones, which gradually decrease in size as they are placed further back ; there are eight or nine teeth of similar size and proportions in each pre- mandibular bone. These teeth are separated by wide intervals, from which other teeth similar to those in place have been detached. The base of each of the above teeth is extentled transversely, compressed antero- posteriorh', and anchylosed to a shallow alveolus, extending across the shallower alveolar groove. An affinity to the lizard tribes is manifested by the j:reater develop- ment of the outer as con. pared with the inner wall of the alveolar furrow. The palatine teeth, of which there are three or lour in each palatal bone, are as large as the superior maxillary, and are similarly at- tached : the pterygoid teeth, five or six in number, which complete the internal dental series on the roof of the mouth, are of smaller size, and gradually diminish as they recede backwarils. In the interspaces of the fixed teeth in both these bones, the places of attachment of the shed teeth are al- ways visible ; so that the dental formula, if it included the vacated with the occupied sockets, would express a greater number of teeth than are ever in place and use at the same time. In the smaller species of boa the intermaxillary bone is edentulous. In certain genera of the non-venomous serpents, as Drj/op/iisj Dijjsas, and Bucephalus, u 290 REPTILIA. in which the superior maxillary teeth increase in size towards the posterior part of the bone, the large terminal teeth of the series are tra- versed along their anterior and convex side by a longitudinal groove. In the Bucephalus capensis the two or three posterior max- illary teeth present this structure, and are much larger than the anterior teeth, or those of the palatine or premandibular series ; they add materially to the power of retaining their prey, and may conduct into the wounds which they inflict an acrid saliva, but they are not in connexion with the duct of an express poison gland. The long grooved fangs are either firmly fixed to the maxillary bones, or are slightly moveable, according to their period of growth : they are concealed by a sheath of thick and soft gum, and their points are directed backwards. The sheath always contains loose recumbent grooved teeth, ready to succeed those in place. In most of the Cokibri each maxillary and premandibular bone includes from twenty to twenty-five teeth ; they are less numerous in the genera Tortrix and Homalopsis, and are reduced to a still smaller number in the poisonous serpents, in the typical genera of which the short maxillary bone supports only a single perforated fang. In the poisonous serpents the superior Fh. 209. Ifi \U\ , ' Roof of the moutli of t/w lioint of entrance. In the different species of Emydes, which are more carnivorous in their habits, ami in the Trionyx. the alimentary canal is shorter — at least the large intestine, which is not longer than the small; and the latter is continuous with the large intestine, without there being any insertion of one into the other. The CrocodiliclcE differ from all other saurian reptiles in the form of their oesophagus and stomach. The cesophagus is a narrow canal, easily distinguishable troni the stomach on account of the globular form of the latter, and also by the different structure of mucous and ce.lular coats, the former of which is plicated and villous in the oesophagus, while the latter is very thin, and hardly perceptible. The stomach is a great rounded globular cul-de-sac (;%, 21 3.), into which the oesojihagus opens, at no great distance from the pylorus. Close to this insertion there is, interiorly, a small cul-de-sac {g), the cavity of which is se- parated from the larger cul-de-sac by a narrow passage, and which opens into the intestine by a constricted orifice. Necessarily, ali- mentary substances must pass through this channel into the pyloric cul-de-sac, in order to escape from the stomach. This structure evidently corresponds to the pyloric portion of the stomach in ophidian reptiles, to be described hereafter. Generally, the parietes of the stomach are very strong; the mucous lining is smooth, thick, and very glandular, forming here and there broad Iblds, which run in a serpentine manner, like the convolutions of the brain. The cellular tunic, which was not vtry dis- tinct in the oesophagus, becomes so in the stomach, whilst the muscular coat almost equals in thickness that of the cellular and raucous tunics combined : it is principally con^posed of fasciculi, which radiate from the centre towards the circumference, arising from an aponeurotic disc, which exists on both the abdominal and dorsal aspects of the organ. This stomach very nearly resembles the gizzard of a bird ; and the resemblance becomes more striking if it be compared with the gizzard of a heron, the wals of which are thin, and which also opens into a little appendage. The small intestine in the Nilotic crocodile may be distinguished into two portions : the first of these is wide, with thin walls, and is bent four times upon itself, so as to make four permanent folds : this portion is equal in len^jth to about four-tenths of the whole I 4 296 REPTILIA. length of the intestine, and corresponds to the duodenum of birds. The other part is of smaller diameter, and has thicker walls, en- closing between the mucous and muscular tunics a layer of glandular substance, re- sembling a greyish, semitransparent pulp. The lining membrane of the intestine which covers this glandular layer is disposed in longitudinal zig-zags, connected together by little folds that pass from one to another, so as to constitute a fine net-work. These zig-zags are replaced by delicate villosities in the first portion of the small intestine, where the glandular layer is not perceptible ; and towards its termination in the large intestine, they become reduced to undulating folds, rarely joined together by transverse plicae. In the larger intestine itself, they are con- verted into irregular projections, which form a sort of villous surface. In the other families of saurian reptiles, the form and structure of the stomach may be referred to the common type which we have already seen in the Chelonians. The oesophagus is wide, with very extensive walls, as is indicated by the longitudinal folds of its lining membrane ; it is generally of the same diameter with the stomach, which latter forms a cylindrical or conical bowel, directed from before backwards, and generally bent a little towards the right near its termination, so that we may distinguish a pyloric portion extending from the bend to the pylorus, the length of which is very variable, and which is distinguishable from the rest of the stomach by the greater thickness of its coat. At the entrance of the duodenum there is a promi- nent muscular ring, serving the office of a pyloric valve. The great curvature, which is generally more dilated, is sometimes, though rarely, prolonged into a small cul-de-sac {Monitor of the Nile). The small intestine of the Lacertidcs \?, short and sometimes very capacious in the first half of its extent ; the other half presents ligamen- tous bands, which produce puckerings and constrictions corresponding internally with transverse ridges that intersect the oblique folds of the lining membrane. This latter in the large intestine forms transverse valves, dividing its cavity into numerous pouches. The Iguanas, which live entirely upon fruits, grains, and leaves, have no caecum, properly so called, indicative of this regimen ; but their large intestine is prodigiously de- veloped, and its cavity extended by numerous internal folds of the lining membrane. In the Ophidian reptiles, the oesophagus and stomach form a continuous canal of va- riable length, in which it is generally difficult to say where the one terminates and the other begins ; it may be remarked, however, that the walls of the oesophagus are thin, and the longitudinal folds of its fining membrane small and few in number, whilst the commencement of the stomach is indicated externally by a strengthening of the muscular fasciculi, and internally by thicker and more numerous longitudinal plic£E of the lining tunic, which often undulating, and here and there ir- ilar. These folds are only visible when Fig. 216. Alimentary canal of Draco viridis. a, tongue ; b, larynx ; c, opening leading into the guttiiral sac; d, laryngeal sac, e, oesophagus; /, stomach ; g, g, small nitestine ; h, caecal appendage to the commencement of the colon ; i, colon ; k, the cloaca. the stomach is empty. Sometimes the cardiac commencement of the stomach is indicated by a kind of cul-de-sac. The stomach of serpents is remarkably short in relation to the length of the animal and the extent of the oesophagus; its situation also is very far back, so that the prey which the animal swallows will be lodged partly in the oesophagus and partly in the stomachal cavity. The latter may be divided into two portions, one of which Cuvier calls the "sack'" and the other the pyloric portion. The " sack " has a very different appearance when empty to that which it presents when distended with prey : in the first case, its walls appear thick and muscular, whereas in the second they are very thin and extensible. Before terminating in the intestine, the stomach becomes considerably diminished in its diameter, and is converted into a narrow channel of variable length in different genera and even in different species, which is but little susceptible of dilation, and into which the food only passes after being digested in the first portion. This second division of the stomach may be continuous with the axis of the former; at other times it seems to be given off" from one side. It may be more or less bent upon itself, or even form several curvatures in different directions, or pass straight into the intestine. When the stomach REPTILIA. 297 is empty, the pyloric portion may be distin- guished from the " sack " by the thinness of its walls and the absence of longitudinal folds in its mucous membrane, which latter be- come gradually obliterated as they approach the pylorus. At its termination, this portion of the stomach can hardly be distinguished from the commencement of the intestine, which it resembles both in the transparency of its coats and in its uniform diameter ; generally, however, the walls of the intestine are thinner and more transparent than that of the pyloric portion of the stomach, and its diameter sensibly increased. Internally, there is a very perceptible difference in the structure of the mucous membrane lining the two, which, in the pyloric portion of the stomach, is arranged in small longitudinal rugae, but in the duodenum has a shaggy or villous appearance. Generally there is a valve or circular fold separating the stomach from the intestine, but this is sometimes only re- presented by a prominent ring formed by the mucous and cellular coats, and occasionally is altogether wanting. It is in that part of the stomach which Cuvier calls the " sack " that the digestion of food is accomplished. Tiie pyloric portion forms a first obstacle to stop the prey, which descends to the bottom of the stomachal " sack," where the digestive process is most rapidly carried on, for it is here that the dis- solution of the animal swallowed always com- mences. In proportion as this dissolution goes on, the pyloric canal, the diameter of which is always very small, allows the digested portions of food to pass successively into the intestine. The intestinal canal in the common or ring- snake runs in an undulating manner from the pylorus to the rectum, preserving pretty nearly ihe same diameter throughout its whole ex- tent, except that it dilates a little to form the colon. The Hning membrane of the small intestine forms broad longitudinal laminre, folded like a shirt-sleeve. In the large intes- tine, which runs straight to the cloaca, the folds are thick and irregular. In the true serpents the arrangement is different : the first portion of the intestine forms numerous loops, more or less closely bent upon each other, and retained in position by bands of peritoneum passing between them. The whole is enveloped in a long cylindrical cell formed by the peritoneum. This disposition of a part of the alimentary canal in the true serpents, distinguishes them from all other vertebrate animals ; it seems to be rendered necessary by their manner of progressing upon their belly, which, without this precaution, might injure their intestines : it must, however, render slower the peri- staltic movements, and thus contribute to produce the extreme lentor of all their di- gestive functions. This seems to be proved by the fact, that in water serpents {Hi/drus, Platurus, Chersi/drus') the intestine is a con- tinuous cavity, and not divided into several loops, their movement in the water not re- quiring such arrangement. In the Ophidian reptiles we may always distinguish a large and a small intestine ; the Fig. 217. Viscera of the Rattlesnake, a, the trachea ; b, the right hang ; c, bladder-Hke termination of ditto ; d, e, f, the oesophagus ; the stomach ; h, commencement of the intestine, 1 ; /, the heart ; m, large arterial trunks ; n, n, anterior and posterior venai-cavie ; o, the liver ; p, the gall- bladder, situated at some distance from the liver. latter generally terminates end to end in the former, and it is rare to find anything like a cul-de-sac or caecum at the place of their union. The small intestine preserves nearly the same diameter throughout. The large intestine, which is shorter, is generally divided into two or sometimes three com- partments by one or more sets of valves, or even by one or two partitions, through which there is only a small opening leading from one compartment to another. The first compartment is generally smooth, or only presents internally a few "simple folds ; whilst the last compartment, or the rectum, pro- perly so called, has its cavity divided by irregular transverse plicae, or even by very broad valvulae conniventes. When there is an intermediate compartment, its sides are 298 REPTILIA. smooth, or nearly so, like the first ; but the communication between it and the third is always very narrow. Generally speaking, every arrangement seems to have been made to retard the passage of alimentary substances, and of the residue of digestion ; or at least to prevent their passage from being too much accelerated by the act of creeping, and the contractions of the abdominal nuiscles ne- cessary for its performance. The lining membrane of the small intestine is thrown into longitudinal folds of variable breadth, and more or less thick and numerous, which extend throughout its whole length, but which sometimes are connected together by transverse bands, so as to form cells. Some- times these folds are beautifully fringed in the first portion, so as to give the mucous lining a villous appearance ; and they have been observed quite white, with chyle filling their lacteal vessels. The liver of reptiles is but indistinctly di- vided into lobes, and frequently is only irre- gularly notched upon its free border. Its relative size, in this class of animals, is very considerable. When the body is broad, it occupies a large proportion of both the hy- pochondriac regions ; but when the body is elongated, it is situated in the right hypo- chondrium only, but extends very far back by the side of or beneath the intestines, in which position it is maintained by fokis of peritoneum, resembling those which form the air-cells of birds. In the Clielonians the liver is divided into two rounded irregular masses ; one of which fills the right hypochondrium, whilst the other, which is connected with the smaller curvature of the stomach, extends into the epigastric and left hypochondriac regions : these two divisions are only connected to- gether by two narrow processes, which bound a space through which the principal hepatic vessels pass. In the crocodiles, whose digestive organs, in many respects, resemble those of birds, the liver consists of two distinct lobes, united to- gether by a narrow central portion. In the spectacled Caiman {Crocodilus scle- rops), the right lobe is the largest, whilst the left is small and triangular. Tliese two lobes separate anteriorly to receive the heart. The gall-bladder is always connected with the right lobe, but is here quite detached and separate from it, — a circumstance which holds good likewise in the Gavials ; whilst in the Crocodile it is closely connected with the right lobe. Among the LaccrtidcE, the monitors have likewise tv^o lobes to their Uver, which are sepft*'«4ed by a deep fissure. In the safe- guards (Av^eiva) this fissure is less decided, and the right portion of the viscus is prolonged backwards to a long, narrow, pointed appen- dage. This form conducts us gradually to the shape of the liver most generally met with in other Saurians, in which the organ consists of a single mass, rarely divided by deep fissures, but slightly notched at its mar- gin. This mass is generally of a triangular shape, which is lengthened out in accordance with the form of the body, sometimes ex- tending backwards quite to the posterior boundary of the abdominal cavity. In the Ophidian reptiles the liver is not divided into lobes, but forms a long cylindrical mass. The gall-bladder is, in the Chelonian rep- tiles, almost entirely imbedded in the right lobe of the liver, and is generally of very great size ; whilst in the Saurian reptiles it is generally situated at the bottom of the fissure which separates the two lobes. In the Ophidian reptiles, the position of the gall-bladder varies ; in the genera Anguis, Am- phisboema, and Cecilia, it is more or less in- crusted by the substance of the liver; but, in the true serpents, its position is very remarkable, for it is not only entirely se- parated from the liver, but is removed to a considerable distance from that viscus, and placed in the immediate vicinity of the pylorus. In all reptiles the bile is conveyed into the gall-bladder by the branches of the hepa- tic ductSy which open either into its fundus, its neck, or into the commencement of the cystic canal : in the (^helonians, a very large proportion of the bile would seem to pass through the gall-bladder. In the Tor- toises, which have the gall-bladder imbedded in their liver, the hepato-cystic vessels open immediately into its cavity. In the Emydes, the hepatic ducts unite to form a canal, which joins the neck of the gall-bladder. Amongst the Crocodiles, the spectacled caiman has its bile-ducts arranged almost in the sa*me manner as in birds ; the right hepatic canal opening immediately into the gall- bladder. In the other Saurians, and also in Ophidian reptiles, the hepatic duct unites v.ith the cystic, so that the gall-bladder is filled by the reflux of the bile; generally, there is only one hepatic duct, but in other cases there are several, which enter the cystic duct near the neck of the gall-bladder, as, for instance, in Trigonocephalus. The pancreas is present in all reptiles, and is generally situated close to the point where the stomach terminates in the intestine, to which it is most generally adherent. In the Chelonians its shape is irregularly triangular, being narrow and thin in the vicinity of the pylorus, broad and bifurcated at its opposite extremity, by which it adheres to the spleen and to the large intestine. In the Saurians it is generally placed close to the pyloric por- tion of the stomach, and is divided into two branches, one of which accom[)anies the biliary canal ; the other adheres to the spleen. These two branches unite in the vicinity of the pylorus, and furnish a duct which o()cns into the intestine along with that of the gall-bladder, which not unfrequently is imbedded in the substance of the [pancreas. A similar dis- position occurs in all the Ophidian genera. The spleen is in the Reptilia always present, but its relations with the stomach are by no means so constant as in birds and Mammalia. REPTILIA. 299 Viscera of the Female Tortoise. (Emt/s Europceus.') The Imngsand Lymphatic Vessels have been removed, to exhibit the Course of the principal Blood Vessels. A, arch of the right aorta ; b, arch of the left aorta ; c, the pancreas ; e, trachea ; e', e', right and left bronchus ; f', f', right and left subclavian arteries ; h, the clitoris, lodged in the ca\'ily of the cloaca, showing the deep urethral groove running along its dorsum ; i, i', lobes of the liver ; k, k', the stomach ; L, common trunk formed by the union of the right and left aorta ; m", m', m', the right and left oviducts ; N, the ovarium ; q, termination of the urethral groove, at the extremity of the clitoris ; u, u, super- numerary lateral bladders, opening by wide fissures into the cloaca on each side of the clitoris ; u', urinary bladder ; x, the spleen ; d, vena-cava inferior, opening into the rrght auricle of the heart ; e', g, h, i, trunks of the jugular and subclavian veins. It is frequently connected with the com- mencement of the intestinal canal. This is the case in the Chelonian reptiles {fig. 218. x.), it is fixed to the duodenum, not far from the pylorus, behind the opening of the ductus com- munis choledochus, and the head of the pan- creas (c). In the Trionyx it, togetiier with the head of the pancreas, is inclosed between the layers of the mesentery ; and in the Turtle is contained in the first loop formed by the duo- denum, close to the pylorus. In the Crocodile of the Nile it is attached to the left side of that portion of the intestine which imme- diately succeeds the first loop : whilst in the Caiman it is placed between the layers of the mesentery adhering to the second intestinal loop, close to the pancreas. In Lizards its usual position is at the side of the stomach. The spleen in Ophidian reptiles belonging to the genera Anguis and Cecilia, is situated rather behind than in front of the pancreas, close to the commencement of the intestine ; but in all the true serpents it is situated in front of the pancreas, to which it is closely attached, or indeed sometimes imbedded in its substance, receiving from it numerous veins of large size, which sometimes appear to form a sinus between the two organs, which are moreover connected by fibrous bands, and bound down by the same folds of peritoneum. The abdominal viscera of reptiles are re- tained in sitii by numerous mesenteric folds, the 300 REPTILIA. arrangement of w hich varies in different races. It must be remembered that throughout the entire class there is no diapiiragm or other septum dividing the viscera of circuhition and respiration from those of digestion, all being inclosed in a common cavity, lined by the pleuro-peritoneum, which gives off processes to inclose and to fix them as far as is neces- sary in their respective situations. In the tor- toises, that portion of the mesentery which attaches the small intestines, does not come immediately from the vertebral column, and only forms the mesentery after having fixed the transverse colon by a meso-colon. This remarkable disposition depends upon the ge- neral arrangement of the pleuro-peritoneum, and the extent of the cavities that it forms for the lodgment of the lungs. The meso-rectum also is derived rather from the lateral regions of the pelvis than from its middle. There are, besides hepato-gastric laminee, which pass from the liver to the stomach, hepato-duodenal laminee, between the liver and the duodenum ; transverse gastro- colic laminae, which pass from the stomach to the transverse portion of the large intestine ; and duodeno-colic layers connecting the duodenal loop with the as- cending colon. On the right of the mesorec- tum, there is an expansion which descends from the dorsal portion of the abdominal walls to join the proper mesentery. Lastly, the large intestine commences by a loop which is bound down by peritoneal laminae. In the Saurian reptiles, the mesentery is well developed, that portion which is con- nected with the large intestine, as well as that which sustains the small intestine, coming off from the vertebral column. There is no trans- verse mesocolon. The pleuro-peritoneum of Ophidian reptiles presents some varieties in its disposition. In the Anguidae, a mesentery is given off from the whole length of the front of the vertebral column anteriorly : this serves to suspend the oesophagus and stomach, furnishing hkewise a mesenteric fold to each lung, and to the liver. After enveloping the liver it forms a suspen- sory hgament attached to the mesial line of the ventral aspect of the abdominal walls, so that the whole may be regarded as forming two bass connected together, both above and below, along the middle line of the body, and thus dividing the abdominal cavity into two compartments by a vertical septum, extending along its whole length. In the Ct'ciliae a similar disposition exists. In the true serpents the pleuro-peritoneum forms a ceH around the intestine, which con- tains likewise small omental folds loaded with fat : the intestine itself, moreover, is folded into numerous festoons connected to each other by fibro-cellular bands. The large intestine in serpents has no connexion with the stomach, or with the commencement of the intestinal canal, as is almost invariably the case in other vertebrata. Lymphatic Si/stem, — The lymphatic vessels in reptiles appear to be completely destitute of valves, except at the points where they ter- minate in the veins; a circumstance which explains the facility with which they can be injected from trunk to branch. In the Chchnian reptiles the lymphatics of the alimentary canal, especially those of the stomach and small intestine, form two prin- cipal layers, of w hich the inner one constitutes a very delicate net-work *, so thin as only to be well seen with a magnifying-glass, lying close to the inner surface of the intestine, interlaced amongst the blood-vessels, but easily distin- guishable from their continuity. The external layer is made up of larger branches, which are so numerous that they touch each other, and after a successful injec- tion completely cover the intestine they all affect a longitudinal direction, and have an undulated or wa^•y appearance. The lymphatics of these two layers serve to form another net-work placed external to the last, made up of large confluent branches, which convey the lymph into the principal lacteal trunks of the mesentery, which latter form a fourth net-work, the meshes of which are very close and fine. In the urinary bladder and the oviduct, the arrangement of the lymphatics is similar to the above. In the lungs they form a superficial layer, made up of large trunks ; and a deep-seated layer, composed of very fine branches. The external net-work of the gall-bladder is made up of very small meshes ; whilst that of the spleen, on the contrary, consists of large confluent trunks, resembling sinuses : the latter organ, however, has likewise a smaller deep- seated set of lymphatic vessels w hich accom- pany the ramification of the veins into its in- terior. The lymphatics of the testicle have a ramified or arborescent arrangement, increasing in size as they pass from the outer to the inner margin of the organ, the branches forming numerous anastomoses amongst themselves. The adipose tissue, situated between the peritoneum and the carapax, is full of lym- phatic vessels. Those of the peritoneum are very small and numerous : their direction is generally from before backwards. The liver seems to possess very few h-m- phatics, and these Panizza was unable to in- ject, as also those of the oesophagus. Among the Saurian rei)tiles the lymphatics have been examined in the Caiman, and in several species of lizards. In the former, the cloaca, the rectum, and the intestinal canal inclose several net-works of lymphatic trunks, the form and disposition of which varies. There is one upon the inner surface, and ano- ther upon the outer surface, the meshes of which are very close, and the vessels much convoluted. In the rectum, the lymphatics form two layers, one superficial, the other deep-seated ; in the former the vessels are large and their * Panizza Sopra 11 Sistema Linfatico dei Rettili, &c. Ta^ia, l&oo. in foL with six plates. REPTILIA. 301 direction transverse, whilst in the latter the canals are smaller, and their course longitudi- nal. In the small intestine, likewise, there are two layers of lacteal vessels, one superficial (the peritoneal), and the other deep-seated. There is, moreover, a third stratum, composed of very fine lymphatics, which penetrate as far as the viUi of the mucous membrane of the intestine. In the stomach they are com- paratively few in number. The lymphatics of the lungs form a net- work, the meshes of which are scattered and are irregular ; upon the heart they are very numerous, inclosing rhomboidal spaces. In the green Uzai'd the lymphatics form a beautiful plexus around the corpus caver- nosum, and a complicated net-work upon the cloaca ; but it is remarkable that Panizza was not able to inject the lymphatics of the limbs, nor those of the testicles or kidneys. In Ophidian reptiles, the whole extent of the alimentary canal, with the exception of the oesophagus, is covered with lymphatic vessels, which are disposed in two layers, one deep-seated, made up of very delicate tubes, the other superficial, the vessels of which are larger. The kidneys also are very rich in lym- phatics. The central parts of the lymphatic system of reptiles, corresponding with the rcceptacii- lum chyli and thoracic duct of mammalia, are extraordinarily capacious. They resemble, in fact, great serous cavities which are never entirely filled with lymph, but which establish a communication between the lymphatics of the viscera and other organs, and the veins situated in front of the heart. These reser- voirs embrace the principal arteries, and even the veins that they encounter in their passage, covering them as with a sheath {Jig. 219, c). The lymphatics from the different organs, as they run towards these receptacles, form plexicose chains or detached branches, which are more or less knotty in their calibre. In the Chehnian reptiles, according to Hewson, all the lymj)hatics derived from the hinder part of the body terminate in a plexus which surrounds the right aorta, and from thence open into a reservoir situated further forward beneath tiie left aorta. This latter Viscera of the European Tortoise lyi situ, seen from behind. E, the trachea ; c c, great central reservoirs of the lymphatic system surroiinding the principal arterial and venous trunks ; f f, subclavian vessels divided ; b b, h h, i i, tnmks of the large vessels derived from the arches of the aorta; ii, lateral margins of the liver; z z, the lungs; o o, the kidneys; N, external iliac artery ; u u, lateral supplementary bladders ; v v, urinary bladder dilated transversely ; H, the penis retracted into the cloaca ; k, termination of the urethral groove. {After Bojanus.) 302 REPTILIA. gives origin to two thoracic ducts, or rather to several principal trunks, which, as they advance, form two compHcated plexuses, ex- tending as far as the subclavian veins on each side, where they receive the lymphatics of the head, neck, and anterior extremities. On the right side, two branches pass from the plexus to open into the jugular vein, near its junction with the subclavian ; on the left side there is only a single lymphatic trunk, which opens into the jugular near the same point. Among the Saurian reptiles the arrange- ment of the lymphatic system is as follows. In the pike-headed Caiman, there is a sacral plexus formed by the lymphatic vessels de- rived from the tail, and the posterior ex- tremities under the vertebra, which represents the sacrum ; this plexus is continued along the aorta and the vena cava, the former vessel being in some places quite inclosed by it : this forms the principal reservoir of the lym- phatic system. Opposite the third and fourth lumbar vertebrae, this reservoir receives the anterior triuiks derived from the lateral pelvic plexuses, as well as those of the kidneys and of the loins ; it then runs forward and sliuhtly to the left side, above the vena cava, where it receives the lymphatics of the mesenteric plexus. Arrived opposite the conjunction of the two aortae, this reservoir divides into four trunks, which represent the thoracic duct ; these trunks unite and separate again several times as they advance forward : at last they form two fasciculi of vessels, which separate to the right and left, and terminate in the corresponding subclavian veins, having first received the lymphatics derived from the head and neck and anterior extremities. In the green Lizards, the central reservoir of the lymphatics commences a little in front of the anus, by a cul-de-sac, which receives the lymphatics of the hinder extremities, of the kidneys, and of the rectum ; it then ad- vances forwards in the abdomen, becoming considerably dilated, and collects the lym- phatics of the small intestines, and partly those of the stomach. A little in front of the latter viscus there is a constriction which seems to indicate the limit between the reser- voir and the thoracic duct. The latter vessel runs between the oesophagus and the vertebral column ; and afterwards between the latter and the left lung. Arrived at the heart, it divides into two diverging branches, which, running outwards, terminate in the anterior vena cava. In the Ophidian reptiles the central lymphatic reservoir commences in front of the anus, and advances forward inclosed between the layers of the mesentery, be- tween the intestines and the vertebral co- lumn ; becoming much enlarged as it ad- vances forwards, and ultimately terminating in a conical cul-de-sac, opposite the commence- ment of the stomach. This reservoir receives the lymphatics from the tail, from the penis, from the kidneys, the testicles, the intestine, the stomach, and the dorsal region of the spine. A little before its termination in the cul-de-sac it gives off several branches, which, united into a single trunk, form the left thoracic duct. This runs forward between the stomach and Hver, and subsequently between the liver and the oesophagus, to arrive at the region of the heart. The in- ferior or anterior right thoracic duct com- mences by a narrow cul-de-sac situated just behind the pancreas, and receives the lym- phatics of the pancreatic plexus, as well as those from the spleen and gall-bladder. It runs forward above the vena porta and the vena cava ; between the layers of the epi- ploon it receives three considerable branches from the right thoracic duct, and most of the lymphatics of the stomach ; it then expands very considerably to envelope the stomach, and becoming again contracted beyond that viscus, it runs forward beneath the lung as far as the right side of the heart, near the en- trance of the vena cava, into the pericardium, where it terminates by a cul-de-sac, after re- ceiving sevei'al branches from the lungs. Three other considerable lymphatic trunks, one mesial and inferior, the two others lateral, run along the whole length of the body from the head to the base of the heart, conveying into the cardiac plexus the lymph from all the anterior part of the body. The cardiac plexus, which is situated in front of the bai-eof the heart, is formed by the confluence of all the lymphatic trunks, form- ing as it were a central reservoir, being com- posed, first, of the three anterior lymphatic vessels mentioned above ; secondly, by the left thoracic duct ; and, thirdly, by a trunk which combmes the lymphatics of the lung and the right thoracic duct. This reservoir opens into the anterior vena cava. The lymphatic system of reptiles offers one peculiarity of structure which is very remark- able. Besides the usual termination of the principal lymphatic trunks in the venae cavae or in the axillary, subclavian, or jugular veins, it has been discovered that some lymphatic trunks open into small capsules which present alternate movements of contraction and dila- tation, and which propel the lymph that they contain immediately into small contiguous veins : these capsules are therefore lymphatic hearts. Such lymphatic hearts have been found to exist, both in the Saurian, Ophidian, and Batrachian orders of reptiles, the Chelonians only appearing to be without them. They are generally situated near the posterior ex- tremity of the body, and discharge into the venous system the lymph derived from the most remote parts. In the crocodile the lymphatic hearts are found on each side lodged between the upper border of the pelvis and the transverse process of the first caudal vertebra. They resemble elongated transparent bladders, and commu- nicate with the veins of the kidney. In the green lizard they occupy a similar situation, but they open into a vesicle that REPTILIA. 303 empties itself into the principal vein of the corresponding hinder extremity. ^ The l3mphatic hearts are in the snakes situated just above the origin of the tail. They communicate with a branch of the caudal vein, and receive lymphatic vessels from the posterior extremity of the great lymphatic reservoir. In the Pythons, the situation of the lym- phatic hearts is external to the abdominal cavity in a special chamber, which is bounded anteriorly by the last rib ; each heart receives the lymph by three canals that open into its dorsal aspect, and it communicates with the caudal veins by two orifices situated at its anterior extremity. Each of these lymphatic hearts is composed of three membranes; an external one, which is celhilar ; a middle one, vsrhich is muscular, the muscular fasciculi being arranged as in the hearts of the higher ani- mals; and an inner coat, which forms valvular folds, serving to prevent the escape of the venous blood into the lymphatic system. These lymphatic hearts are without peri- cardium, and adhere to the walls of the cavity which contains them, In a Python Tigris of seven feet long, the length of each lymphatic heart was six lines, and its diameter four lines and a quarter. Vejious System. — TJhe veins of reptiles have very thin walls, and Exhibit no fibres in their structure, except in the large trunks of spe- cies of considerable size. In the Chelonians and the crocodiles they are furnished inter- nally with a few valves, but these, it would appear, do not exist in the veins of Ophidians, at least they can be injected with facility in any direction. As in other Vertebrata, the veins of reptiles are more numerous than the arteries, and from the frequency of their anastomoses re- present rather a net-work than an arborescent arrangement. Their circulation, moreover, not being confined to a determinate course through the lungs, as in Mammalia and birds, the venous system in the Reptilia is never overloaded with blood, as must be the case in the two former classes, when respiration is suspended. And it is probably on this ac- count that their veins appear less capacious, as compared with the arteries, than in those Vertebrata which possess a double circulation. For the same reason they are not dilated into reservoirs as they are in Mammalia and diving birds, or as in fishes, where the blood has but one route through the branchiae. The Chelonians have two posterior vencB caves which traverse the liver on each side and receive in their course a multitude of small hepatic veins. Immediately after issuing from the liver, they are each joined by an an- terior vena cava of the corresponding side, or by the connnon trunk of the jugular and subclavian, all of tliem opening into a kind of reservoir, which communicates with the right auricle of the"* heart through a slit-like orifice guarded by t\Vo valves. The two veins called above posterior venae cavae are the umbilical veins of Bojanus, the analogues of the single abdominal or median vein of the Batrachian reptiles, which become confluent by winding towards each other an{l assuming a transverse direction in the isthmus that unites the lateral lobes of the liver : it is into this single transverse trunk that the two abdominal veins open. Each abdominal vein communicates by a pectoral branch with an intercostal vein, and by this intermedium with a cervical branch from the jugular. Each abdominal vein has, moreover, an anastomosis posteriorly with the inferior common intercostal ; it is essentially a con- tinuation from the iliac vein, which receives the blood from the femoral, from the iliac cir- cumflex vein, from the ischiadic, from the caudal, from the hypogastric, and from the renal, through the descending trunk of the vena azygos. This latter, after anastomosing in front of the thorax with a cervical branch from the jugular, seems to convey the blood from before backwards, if we may judge from the gradual dilatation of its calibre, as it re- ceives the intercostal veins, the muscular veins of the back, and the branches of the vertebral veins. Its trunk, as it descends towards the kidney, anastomoses with the vein derived from the generative organs, and joins the hypogastric to form the iliac : here, then, we have an arrangement of the venous system which determines the direction of the blood towards the liver, and makes the ab- dominal vein relatively to the liver what the pulmonary artery is to the lungs. A vein derived from the organs of generation, which, as already stated, anastomoses with the trunk of the vena azygos, likewise runs to the liver, traversing its right lobe like a vena cava, and in the same way receives many small hepatic veins and terminates immediately that it issues from the liver in the great sinus, com- mon to the veins of the body. Arterial Si/sfem. — In reptiles there are always two distinct aortae given off' sepa- rately from the heart, and a third artery destined exclusively to the lungs. ' In the Che/onian order, the two aortae, together with the pulmonary artery, are united together for a little space ; but the former soon separate to take the position and character, one of the right, and the other of the left posterior aortae. The right aorta gives off", shortly after it;:; commencement, a considerable artery, which might be called the anterior aorta, which soon bifurcates ; each division again subdividing into tw^o others, namely, the common carotid, and the sub- clavian. The subclavian gives off almost the same branches as in the mammalia ; namely, — 1. An artery analogous to the inferior thyroid of Mammalia, which supplies a very vascular cavernous little thyroid body, situ- ated at the bottom of the neck. 2. The co??»»o« cervical, which runs forwards under the neck internal to, and beneath the carotid, distributing branches to the muscles and other organs of the throat. 304 REPTILIA. 3. A little artery appropriated to the sub- clavian muscle. The subclavian then bifurcates to form a large ascending branch, and a smaller ex- ternal branch. From the ascending branch arise — 4. The superior cervical (vertebral of Bqjanus) which supplies the muscles of the superior region of the neck, gives off some spinal branches, and at length becomes con- founded with the cervical recurrent. o. Two small spinal branches for the vertebrae of the neck. 6. An intercostal branch, which divides to form the two anterior intercostals. 7. The ascending branch of the subclavian then turns downwards and backwards to form the analogue of the internal mammary, which runs along the external margin of the carapax, receives in succession the intercostal arteries, and ultimately becomes continuous with the epigastric. 8. The external branch, which is the con- tinuation of the subclavian, gives off several arteries to the muscles of the shoulder, and to the great pectoral muscle, and then termi- nates by becoming the axillary arterv, which, after giving off twigs to the muscles of the shoulder, becomes in turn the brachial artery. This latter immediately gives oft^ three branches analogous to the drcinvfJex. and to the profunda humeri. It then runs down, remarkably diminished in size, to the bend of the elbow, where it divides into two feeble trunks, the radial and the ulnar, the small size of which is proportionate to the small dimensions of the muscles and other parts of the fore-arm and hand : upon the palmar surface of the latter the ulnar artery forms an arch, as does the radial on its dorsal surface, and from these arches collateral branches are given off in the usual manner to supply the corresponding margins of the fingers. Arteries of the Xech and Head. — The common carotid runs forward upon the side of the neck, hidden by the muscles connected with the os-hyoides, and in its course sends 220. llscera o f the Female Tortoise (Emys Europtpus). A', rentricle of the heart ; a, common trunk of the arterial system ; b', right auricle ; B , left auricle : B, trunk of the right aorta ; c, common trunk of the pulmonarv arteries ; D. trunk of the left aorta ; e, trachea : E'E", carotid arteries ; 1 1. right and left lobes of the liver; k, the stomach ; k', commencement of the intestinal canal ; m m, terminarions of the right and left oviducts ; x, ovarium ; t t, oesophagus ; r, urinary bladder; u' r", right and left supernumerary bladders; x, external opening of the cloaca; v, the rectum; z, the lungs ; c, e, g, h, i, truncated vessels arising from the aorta. REPTILIA. 305 branches to the oe55ophagus and neighbouring muscles, until it reaches the head, to which it is distributed without previously dividing into two principal branches, representing the two carotids of mammalia. This difference doubtless depends upon the small size of the encephalon in these reptiles, and it may be remarked that the comparative smallness of the internal carotid, which is here only a subordinate branch of the ex- ternal carotid, is not compensated by the size of the vertebral artery, which in the Chelonians does not exist. This last cir- cumstance will not be surprising when it is remembered, that in birds the vertebral artery only supphes the muscles of the neck, the cervical vertebrae, and the spinal chord ; fur- nishing in the cranium only a single small branch, which is entirely expended upon the medulla oblongata. As in birds, the internal carotid of the Chelonians supplies all the parts of the en- cephalon. There is a posterior communicating branch, which forms, in conjunction with its fellow, a basilar artery ; which, as it is prolonged backwards beneath the spinal chord, forms an inferior median spinal artery. This last azygos artery gives off near its origin a re- current branch, which is the superior lateral spinal. The external carotid, which is the principal carotid trunk, resembles in its distribution very closely the external carotid of mammalia ; it may, however, be remarked, that after giving off the lingual branch this artery pene- trates into the temporal fossa through the external carotid canal, and that it there divides into two principal branches, one an- terior, the other posterior ; the former is appropriated exclusively to the head, and supplies the place both of the internal maxillary and of the temporal of mammalia. The posterior branch of the carotid repre- sents an occipital arterj^, of which the cervical branch is very greatly developed, so that this occipital seems to be transformed into a re- current cervical artery, which runs backwards over all the dorsal region of the neck, giving branches to the muscles, to the vertebrae, and to the medulla spinaUs, and ultimately anas- tomoses with the superior ascending cervical artery, derived from the subclavian. The quantity of blood which is thus furnished to the spinal chord of the neck by the recurrent and ascending cervical arteries is very re- markable. Branches of the right posterior Aorta. — The two posterior aortae, in the first instance, run upwards and outwards towards their respective sides, and then turning backwards approach each other so as ultimately to unite nearly opposite the fifth dorsal vertebra by a com- municating branch which the left aorta fur- nishes to the right. Before, however, receiving this artery, the right aorta gives off several branches corresponding with the anterior intercostals. After receiving the communicating artery, VOL. IV. the right aorta runs backwards beneath the vertebral column as far as the pelvis, giving off in its course the following branches ; — 1st, five arteries on each side analogous to the intercostals ; 2d, the spermatic ; 3d, several renal branches to the kidneys on each side ; 4th, several small lumbar branches ; 5th, a small artery analogous to the posterior mesenteric, which is distributed to the cloaca; ultimately, the right posterior aorta terminates by four branches, namely, 1st, the left ex- ternal iliac ; 2d, the left internal iliac ; and 3d, the common iliac of the right side. Between the two latter trunks arises the caudal artery analogous to the middle sacral. In the green turtle {Chelonia Mydas) the six last inter- costals are given off immediately from the right aorta : but in the Emys europea their origin is very different, the five last inter- costals being derived from a common anterior intercostal, which arises from the ascending branch of the subclavian. This vessel runs along the spine from before backwards, as is the case in many birds, and ultimately termi- nates by uniting with a posterior con)mon in- tercostal : this latter is a branch derived from the iliac artery. The divisions of the internal arteries re- semble very closely what is found in mammalia. These vessels first separate into two branches, one of which gives off vessels to the bladder and to the cloaca ; the other plunges into the pelvis, and apparently represents the ischiadic and posterior iliac arteries : the external iliac runs forward along the edge of the pelvis, giving off the analogue of the epigastric, from which arises the anterior iliac. Leaving the pelvis, the external iliac takes the name of crural, and after giving off' the circumflex arteries, and the profunda femoris, continues its course, in all respects comparable in the remainder of its distribution to what is found in manunalia and birds. The left {Visceral) Aorta. — The left aorta furnishes large arteries to the principal viscera of the abdomen, to which it is almost entirely distributed. As soon as it has passed the cardia it divides into three branches ; of these the first, which is the smallest, furnishes a twig to the oesophagus, and is then distributed to the stomach, representing the coronary artery of mammalia. The second, which is almost as large as the trunk from which it arises, supphes the intestines, the spleen, the pancreas, and the liver. The third branch, intermediate in size be- tween the two others, is the communicating artery, given off to join the right aorta, and from which no branches are furnished. In the Saurian reptiles the distribution of the arterial trunks differs but little from thai above described. In Lizards the two aortae advance forwards out of the thorax ; that of the right side after dividing into three branches, that of the left without any such division. The left aorta v^inds backward upon the side of the neck, and afterwards runs along the vertebral X 306 REPTILIA. column, receiving at the point where it begins to take this direction from before backwards the left branch of the right aorta, which forms a loop in front of it. From the convexity of this loop arises the left carotid. The two other branches of the right aorta wind back- wards, and join together in a similar manner upon the right side of the neck, forming two loops placed one in front of the other. The right carotid arises from the convexity of the loop. The subclavians are given off from each aorta a little before their union, except in crocodiles and the iguana, where they are both derived from the right aorta. The common trunk formed by the union of the two aortce, which takes place just beyond the apex of the heart, gives off in succession numerous pairs of intercostal arteries. It sends, moreover, shortly after its commence- ment, an artery to the oesophagus, and subsequently a small branch to the liver; further backwards it gives off an artery which soon divides into two branches : of these the anterior supplies the stomach, the spleen, the pancreas, and the duodenum ; the posterior, which represents the anterior mesenteric, is appropriated to the intestinal canal. The aortic trunk then gives off in succession the lumbar, the spermatic, the pos- terior-mesenteric, which supplies the rectum, and the renal, which are given off thus late because the kidneys are situated very far back in the abdominal cavity : lastly, it gives origin to the iliacs and the middle sacral arteries. The last-mentioned vessel may fairly be re- garded as a continuation of the aortic trunk, from which the iliacs seem to be mere branches ; a circumstance which is owing to the excessive proportions of the tail when compared with the extremities. In the Ophidian reptiles, the absence of limbs, the existence commonly of a single lung, and the extremely slender and elongated form of the body, concur to render the distri- bution of the arterial trunks very simple throughout this order. These trunks, as in the Chelonians and Saurians, are three in number. Their first divisions, instead of being double and symmetrical, are reduced to single trunks. This is the case, for example, with the pulmonary artery in those serpents that possess but one lung, and also with the com- mon carotid, and the vertebral in the entire order. It is from the convexity of the right aorta, and verv near its origin, that the above branches, destined to supply blood to the head and neck, are derived. The right aorta then winds backwards, passes above the oesophagus, and then running obliquely inwards and backwards, it joins the left aorta at a little distance beyond the apex of the heart. The right aorta gives off, a little after its ori- gin, a small artery that supplies a small round glandular-looking mass situated in front of the base of the heart, and subsequently to another similar body of elongated form, situ- ated beneath the jugular vein. It then gives off the common carotid, which is single in all the Ophidia. A third artery is given off a little further on, which is the conmion trunk of the vertebral and anterior intercostals. >'o other important artery is given off by the right aorta, and when it joins the left' aorta its diameter is very small, so that the greater portion of the blood that this vessel receives trom the heart is supplied to the organs which are situated in front of that viscus : it might therefore be properly named the carotid artery. The carotid artcri/ runs obliquely towards the left side, and advances forward, closely connected to the left jugular vein, between the trachea and the oesophagus, and at length is situated beneath the latter. It gives off a great number of small branches to these parts, and near the head divides into several small arteries, which represent both the external and internal carotids. "SVheu the right aorta approaches the verte- bral column, it gives off, as stated above, a considerable branch, which supplies the place both of the vertebral arteries and the anterior common intercostals. This artery advances beneath the vertebral column, giving off branches on both sides, opposite each inter- costal space, both to the muscles and to the vertebrte of the region which it traverses, and only enters the vertebral column close to the head. This vertebral and intercostal artery likewise gives off recurrent branches, which furnish intercostal vessels behind its point of origin. The left aorta runs upwards, backwards, and to the left side : passes beneath the oeso- phagus, and afterwards beneath the lung until it reaches beyond the apex of the heart, where it receives the right aorta, and con- tinues its course backwards. It continually gives off branches corresponding to the inter- costals and the visceral arteries : those which furnish the stomach, the hver, and the pul- monary sac or sacs, are given off successively from the aorta in its course backwards, so that there is nothing like celiac axis. Nearly opposite the pylorus it gives off^ the anterior mesenteric, which runs parallel to the intestine for half its length, to which it constantly furnishes branches. Further backwards the intestinal canal receives in succession three other small branches from the aorta, which gives oft" as it runs backwards arterial branches to the kidneys, ovaries, and other viscera. Arrived at the termination of the abdomen, it passes on beneath the vertebrce of the tail, in which it becomes gradually expended. Organs of Respiration. — In several species of Lizards the cavity of the fauces is much enlarged by an expansion of the skin in front of the larynx {fg. 216, d.). These laryngeal sacs, as the}- are called, appear to be recep- tacles for air rather than food ; for, although not connected with the larynx, they are ex- traordinarily distended in rage, hich one is the pulmonary artery; the other, at the left and upper part of the ventricle, is furnished at its base with two semilunar valves, and termi- nates in the left aorta There is not any direct communication between the cavities of the two ventricles. The left ventricle, which is rather smaller than the right, and situated behind and somewhat above it, has also two valves at the orifice by which it communicates with the auricle. Like the right ventricle, also, it opens into two arterial tubes, of which the first leads into the left aorta, and is separated from the corresponding orifice of the right ventricle by a cartilaginous septum only. It is important to observe that this septum interrupts the immediate communi- cation between the cavities of the two ven- tricles (for they communicate intermediately by means of the artery from each opening into the left aorta), and constitutes the most essential variation of the structure of the heart in this, from what is found in other Saurians. This first branch, arising from the left ventricle, is bordered by a valve at its origin that nearly closes its cavity. The second artery from the left heart divides REPTILIA. 309 shortly after its origin into three branches, of which one is the right or systemic aorta, the second the right subclavian, and the third the common trunk of the carotid and left subclavian arteries. The left or splanchanic aorta, previous to dividing among the vis- cera, gives off a large branch which communi- cates with the right descending or systemic aorta. The three great arteries, viz. the pulmonary, and right and left aorta, are closely connected together immediately after their origin, and dilate into expansions which are collectively larger than the cavities of the heart. In the common state of circulation the blood passes from the right ventricle chiefly into the pulmonary artery, and partly, also, into the branch arising from it, to enter into the left aorta. The blood of the left ventricle, on the other hand, is thrown into the right aorta, right subclavian, and carotid arteries, a small quantity only passing into the left aorta. When the animal is under water, the action of the lungs being inter- rupted, and the circulation of blood through them suspended, a larger proportion of the contents of the right ventricle must pass into the branch of communication with the left aorta, and it is probable that under such cir- cumstances only does it happen that the blood sent to the various organs is an admixture of arterial and venous blood, as in the Chelonia and other Sauria. In the serpent {Pytlion Tigris, Dauel.) the blood of the general system is collected into a large elongated sinus, formed by the union of the inferior with the right superior cava. The left superior cava winds round the back of the left auricle, receives the coronary veins, and terminates in the lower part of the orifice which leads from the above sinus to the right auricle. This orifice is protected by two elongated semilunar valves. The whole of the inner surface of the auricle, with the ex- ception of these valves and the opposite valve of the foramen ovale, is reticulated with delicate muscular fasciculi. The left auricle receives the blood from the lungs by a single pulmonary vein, and has a similar muscular structure : there is no valve at the termination of the vein in this auricle. The blood enters the posterior or aortic division of the ven- tricle by two crescentic apertures, which are each provided with a single semilunar valve, extended from either side of the septum of the auricle. The fleshy septum, which ex- tends from the base of the ventricle to the space between the roots of the pulmonary and systematic arteries is incomplete at its upper and anterior part, and leaves there a free communication between the pulmonary and aortic chambers : these also intercommu- nicate by several round apertures of different sizes near the apex of the ventricle, which serve to thoroughly blend together the two kinds of blood, before they are expelled, thus mixed, along the three arteries which sepa- rately arise from the ventricles. The origins of the pulmonary artery and left aorta are each provided with a pair of semilunar valves. The carotid arteries are given off fiom the right aorta, which afterwards unites with the left aorta at some distance below the heart. Nervous System. — The brain of reptiles, in Fig. 223. Anatomy of the Brain of Turtle. (^After Sivan.) a. 1, corpus striatum and a lesser oblong eminence seen on opening the lateral ventricle ; on the left side the choroid plexus is seen passing through an opening in the septum, to communicate with that of the right side ; part of the striated body has been removed on the right side ; 2, thalamus of the optic nerve ; 3, optic lobe and ventricle continued forward under the thalami, forming a resemblance of the third ventricle, and then backAvards into the cere- bellum, and to the calamus scriptorius. b. 1, cut surface, from which the striated body has been removed ; it is the crus of the brain, and is somewhat connected with the commissure of the optic nerves : the thalamus on this side has been cut off at its connection with the optic tract. 2, Optic lobe, from which more has been removed than in the preceding figure. 3, Cerebellum, from which more has been removed than in a ; two longitudinal bands are continued on from the base of the optic lobes, and terminate near the calamus scriptorius, by being iinplanted into the anterior portion of the oblong medulla : on each side of these, others les? distinct may be observed. 4, fourth nerve. the completeness of its structure, occupies a position intermediate between that of birds and fishes ; it resembles the former in the smooth- ness of its surface and the small size of the optic thalami, and the latter in the length of the olfactory lobes, and their continuity with the anterior extremity of the hemisphere ; its proportionate size relative to the dimensions of the body is, however, far inferior to that of birds, although it still completely fills the cranial cavity. The olfactory lobe of the brain is hollow, and its cavity communicates with the ven- tricle contained in the cerebral hemisphere. Each hemisphere, as in birds, consists of a central portion, or corpus striatum, the re- lative size of which varies in different orders, and of a nervous expansion which incloses the ventricle above and on its inner side. The optic thalami are small, and occupy their usual position on each side of the third ventricle. The tubercula quadrigemina are situated as ordinarily above the aqueduct : they are of a rounded form, and, as in birds, contain a ventricular cavity, which is in com- munication with the third ventricle. The anterior and posterior commissures of the X 3 310 REPTILIA. brain occupy their usual position, but there is no commissura mollis. The cerebellum is generally extremely small, and in some cases is even reduced to a simple transverse la- mella, which does not entirely cover the fourth ventricle, formed as usual by the separation of the posterior columns of the Fig. 224. c, lateral view of the brain of a turtle ; 1, optic tract ; 2, eras cerebri. d, the same : a portion of the optic nerve has been removed to show the cms cerebri passing upwards. After Swan.) spinal chord. The inferior surface of the brain is almost smooth, presenting no other ele- vations than those formed by the union of the optic nerves and by the tuber cinereum. As there are no lateral lobes to the cerebellum, of course no traces of a pons varolii exist. As in birds, a vascular inflation, which seems to represent the fissure of Sylvius, separates each hemisphere into two lobes, into the posterior of which the lateral ventricle pe- netrates. The pineal and pituitary bodies are met with in all reptiles. In the Chelonian reptiles the cerebral he- mispheres contain as usual a ventricle, in which may be perceived a body analogous to the corpus striatum, presenting an arrange- ment very similar to what is observed in birds, only it is much less voluminous, sd as to occupy a small portion comparatively of the interior of the ventricle. The crura ce- rebri, when they reach the lobes of the hemi- spheres, do not, as in mammalia and in birds, immediately dilate into large ganglia, but curving upwards and backwards, expand on each side into a tubercle, which is the corpus striatum. The optic thalami are very sniali, but the pineal gland which lies upon them is of considerable bulk. The bigeminal tubercles are of a rounded form, and instead of being separated from each other by a slight groove, as in the mam- malia, a deep fissure is interposed between them which penetrates to the roof of the aqueduct, and contains a fold derived from the pia mater. The cerebellum is nearly hemispherical in its form, consisting of an arched layer of nervous substance of equal thickness throughout, which spreads over a portion of the fourth ventricle. The remainder of that cavity is covered by a vascular plexus, derived from the sides of the medulla oblongata, which forms a sort of valve, and by becoming united to the margin of the cerebellum, completes the roof of the fourth ventricle, which is large and prolonged very far back. The anterior columns of the spinal chord form a very distinct projection into the floor of this ventricle, as they advance upwards towards the brain. A similar dispo- sition exists in the crocodiles, and in the Sau-> rian reptiles generally ; the principal differences being that the hemispheres are proportionallj larger, and do not separate from each othei so as to display the optic thalami; the olfactory bulbs also are less cfosely approximated to the cerebral hemispheres, with which they are sometimes connected by the intervention of a narrow pedicle, in which, however, a canal is always to be detected, communicating between the ventricles and the cavity of the bulb. The corpus striatum is comparatively larger than in the Chelonians, occupying a considerable proportion of the base of the Fig. 225. Brain and Nerves of Boa Const ru ior. {^After Swan.') a, anterior lobe of the brain ; b, optic lobe ; c, cerebellum ; d, schneiderian membrane of the nose ; 1, olftictoiy nerve ; 2, optic nerve ; 3, third or common oculo-muscular nerve cut short ; 4, fourth nerve given to the superior oblique muscle of the eye ; 5, first trunk of the fifth ; 6, second trunk of the fifth ; 7, third trunk of the fifth ; 8, hard portion of the seventh nerve ; 9, auditory nerve ; 10, glosso- pharyngeal nerve; 11, trunk of the par vagum; 12, ninth nerve ; 13, ganglion of the sympathetic nerve, as in fig. 226 ; 14, a branch of the s\Tnpathetic nerve passing to the palatine nerve, as in fig. 226. REPTILIA. 311 hemisphere, and projecting consitlerably into the lateral ventricle. The furrow which se- parates the bigeminal bodies is not so deep in the Saurians as in the Chelonian order. The cerebellum is very small, being repre- sented by a transverse layer of nervous sub- stance. In the Op/iidian reptiles the two hemispheres form together a mass which is broader than it is long ; the olfactory bulb is frequently of very large size, as, for example, in the Python 225) ; the corpus striatum is much smaller than in the Saurians. In the Python it is divided. The bigeminal tubercles are almost globular in many species, and much smaller than the hemispheres behind which they are situated. In the Python they are remarkable, inasmuch that they are four in number, and closely resemble the corpora quadrigemina of mammalia. The cerebellum of serpents (Jig. 22-5, c.) is exceedingly small and flattened ; it has the shape either of the segment of a circle or of a thin quadrilateral lamina, which partially covers the fourth ventricle. In reptiles, as in birds, the medulla spinalis is permeated by a canal, which is lined inter- nally with grey substance. In the Saurian and Ophidian reptiles this canal extends as far as the first coccygeal, but in the Chelonians it is shorter. The origin of the nerves derived from the encephalon and spinal chord closely resembles what is met with in the higher vertebrata : their general distribution will be best under- stood by referring to the explanations ap- pended to the annexed figures, copied from Mr. Swan's elaborate work on the Compara- tive Anatomy of the Nervous System. Nerves of Boa Constrictor. (After Swan.) 1, ganglion of the sympathetic nerve, situated near to, and connected' with, the trunk of the par vagum. 2, a branch of the s^Tupathetic nerve passing some way in a canal at the base of the cranium, and forming a small ganglion with a branch of the second trunk of the fil'th ; it sends filaments to the membrane covering the posterior part of the mouth and palate, one of which com- municates again with the second trunk of the fifth before its termination; the ganglion then sends another branch forward to form another glangUonic tmiou with a branch of the second trunk of the fifth, and from this a branch is sent to the posterior part of the nose to ramify on the schneiderian mem- brane ; other branches are given to the membrane covering the mouth and palate, and one passes for- ward and communicates again with a branch of the second trunk of the fifth, and is distributed on the membrane covering the anterior part of the mouth X 4 312 REPTILIA. and palate. It is worthv of remark, tliat the nerves distributed on the membrane of the m(>uth and nose communicate so many times •vrith branches of the second trmik of the fifth, and their connexion is so much greater than in the turtle; but in this creature the palate is homy, and not so extensive in proportion to the size of the head. 3, pro- longation of the sympathetic connected with the trunk of the par vagimi, but nc>t directly with the ganglion of the sympathetic ; it commimicates with the ninth nerve, then passes down the spine and communicates with the eleven superior spinal nerves ; it emerges on each side at the place the superior branches of the vertebral artery enter to distribute branches in the intercostal spaces : it is continued downwards in a very fine plexiform prolongation with the vertebral arterv. as far as the origin from the right aorta : it then branches to each side be- neath the membrane connecting the viscera with the ribs and spine, and communicates with fila- ments of the par vagum ; it is afterwards ccmtinued downwards, receiving a filament from each spinal nerve ; in its course it is a very fine nerve, and has not any more ganglia than the first, and those com- municating with the second trunk of the fifth ; but at different points from which the nerves pass to the viscera, there is an appearance of a delicate plexus : this plexiform structure varies in different parts, and becomes much greater about the be- ginning of the intestine, where it resembles that corresponding with the semilunar ganglion in the turtle ; near the kidney it assumes the fc>rm of a nervous membrane or retina, bef(:)re it is distributed on the urinary and generative organs. Branches pass from the plexuses with the arteries to the dif- ferent viscera. 4, second trunk of the fifth : after communicating with the sympathetic, and giving filaments to the membrane of the mouth, palate, and nose, it passes out of its canal in the upper jaw, and terminates in branches on the upper lip. 5, third trunk of the fifth ; it gives branches to the muscles of the jaws, the greatest portion of it then passes within a canal in the lower jaw: it sends three branches through the opening at the inferior margin of this part, two of them to c<:>mmunicate with the branches of the par vagum and ninth, dis- tributed on the muscles and parts underneath the jaw; the other to give filaments to the memlirane of the mouth as far as the sheath erf the tongue : the trunk is continued onwards through the fora- men, near the chin, to divide into branches and terminate on the lower lip. 6. hard portion of the seventh ; it communicates with the ganglion of the sympathetic, and then passes through the digastric uiuscle, to which it gives a branch : it communi- cates with the first spinal nerve, and terminates on the cos tom axillary muscle, 7, glosso-pharyngeal Si/mpathetic Sj/stem. — The sympathetic sys- tem of the tortoise is so feebly developed as to be detected with difficulty, except in the interior of the carapax, where nerv ous ganglia are distinctly recognisable both in the peri- toneal folds and on the bodies of the vertebrse. The ganglia exactly resemble those of birds; they give off two filaments superiorly and two infrriorly : the latter pass beneath the trans- verse process of the vertebrae, which is here connected with the carapax. From the inner margin of each ganglion a splanchnic nen-e is given off, which runs to assist in forming a plexus, ramifications from which accompany each of the arteries given off by the aorta, and likewise assist in forming a pulmonary plexus. The intercostal ganglia may be traced as far as the sides of the first vertebra of the tail. Bojanus has represented the sympathetic of the European tortoise (^Evir/s evropdea) as nerve : it passes to the ganglion oi the symjiathetic. 8, trunk of the par vagum : it commxmicateiKls a branch to communicate with the ninth, to pass to the musclfes, &c-, of the £Mices; and is then continued downwards close to the trachea, in compiany with each jugular vein ; on the left side it also ac- companies the carotid artery, and from this a small vessel also ascends with the right trunk: it sends filaments on the large vessels towards the heart, and others behind each attrta. similar to the recurrent nerves, to be distributed on the trachea and ceimpanies its corresponding pulmonary artery : a little al'cve the liver it passes in front of the superior pan of the lungs, and proceeds a short distance, where it is joined by its fellow to form a single nerve: this is cctntinued downwards under a thick membrane on the hver, and apipears to give filaments tc- this viscus, the lungs, and oesophagus : abc>ut the termi- nation of the liver it sends a large branch, which has commxmicated freely with branches of the sym- pathetic to the left surface of the stomach : this gives filaments to the lowest part of the lungs, and terminates on the stomach. The right division, or the continuation of the nerve itself having com- municated several times with the 1^ divisi(>n and filaments from the jtlexus of the sympatht-tic- is continued a short way on the membrane connecting the viscera, it passes on the right sairface of the stomach, distributing branches to this viscus. and terminates on the beginning of the intestine, reach- ing as far as the pancreas. 9, a nave from the ganglion of the sympathetic ; it appears tit be the continuation of the glosso-pharyngeal after its junction with the ganglion, it commimicates with the ninth after its connection with a branch of the trunk of the par vagum. and terminates on the glottis and muscles attached to the antm<»- point of the jaw for drawing forward the trachea. 10. ninth nerve ; it receives a branch from the trunk ci the par vagum, and from the hard p«rtion of the seventh ; after this has communic-ated with the first cervical nerves, it gives off several branches to the muscles of the tongue and throat, and. one that reaches to the end of the tongue, and CMie to cc»m- mxmicate with l>ranches of the third trunk oi the fifth, issuing out of the inferior part of the lower jaw. The glosso-jiharyngeal, the trunk erf" the par vagum, and the ninth, are so connected together that it is difficult to determine precisely to which nerve each branch belongs; they have beai with great care af^ortioofid to tbax respectiTe nerves in this descriptioi. accompanying the carotid artery into the cranium, and uniting with the vidian and the facial nerves. On issuing from the cranium, he describes it as being closel\ connected vith the vagus and with the glosso-pharyn- geal nerves, so that it is difficult to say whe- ther a superior cervical ganglion exists or not: and as the cervical vertebra are here devoid of the vertebral canal, the nerve is equallv inse- parably connected with the vagus throuirhout the whole length of the neck. Below the sixth cervical vertebra the sympathetic nen e separates itself from the sheath of the va"hile the latter maintains the more probable opinion, that they act differently in different parts of the thorax. Dr. Hutchinson has also lately made some oljser- vations on the actions of these muscles in Mechco- Chimrgical Transact, of London, vol. xxix. p. "213. [Dr. Hutchinson regards the external intercostais and the intercostilaginous portion of the internal in- tercostais as muscles of inspiration, while the rest of the internal intercostais are muscles of expiration. See a further exposition of this author's vicAvs in the article Thorax. — Ed.] * According to Dr. Hutchinson (Opus cit. p. 187) the chief enlargement of the thoracic cavity in deep inspiration is made by the ribs, and not by the diaphragm. t Part of the muscles passing between the thoracic extremities and the anterior and lateral walls of the chest, here enumerated among the accessory muscles of inspiration, may, in certain cases, act as accessory muscles of expiration, by di'awing the scapulae for- cibly doAvnwards upon the ribs. (Vide observa- tions of Mr. Sibson and MM. Beau and Maissiat.) These authors are not of the same opinion regarding the action of all these muscles ; for, while the two former class the serratus magnus among the muscles of inspiration (Opus cit. tom. iii. p. 268. 1843), the latter affirms that the greater portion of its fasciculi acts visibly in violent expiration (Opus cit. p. 535) : they agree, however, in placing the latissimus dorsi among the accessory muscles of expiration. X The hyoid bone, larynx, and trachea are some- times drawn downwards during violent inspirations by the strong contractions of the sterno-hyoid and sterno-thyroid muscles, causing a depression of these parts, at the same time that they elevate the sternum. hurried ; and in laboured breathing the nos- trils are expanded by the contraction of the muscles, which draw the alae of the nostrils outward. The greater or less demand for fresh air in the lungs regulates the number of these accessory respiratory nuiscles brought into play, and the energy of their contraction. A diminution of the capacity of the thorax or an act of expiration, by which part of the air is expelled from the lungs, follows imme- diately each inspiratory movement. In ordi- nary respiration, after the muscles of inspi- ration have ceased to contract, the elasticity of the thoracic walls, especially of the carti- laginous portion, causes it to return to the state in which it was before its dilatation ; and when the contracted diaphragm has re- laxed, the elasticity of the parts displaced by its descent, is sufficient, without much, if any, aid from the abdominal muscles, to push the diaphragm again upwards. The gas present in greater or less quantity in the digestive tube, being compressed during the descent of the diaphragm, will, from its elasticity, assist in pushing upwards the relaxed diaphragm.* In more forcible expirations, when the walls of the chest are compressed beyond the state they assume when the muscles of inspiration are relaxed, the compressing muscles expe- rience considerable resistance from the elas- ticity of the w alls of the chest. When the ex[iirations are performed more forcil)ly than ordinarilj', the diaphraum is pushed up, and the sternum and ribs de- pressed by the contractions of the three broad muscles of the abdomen, by the recti abdo- minis, and by the triangularis sterni muscles. The levator ani, one of the antagonist muscles of the diaphragm, assists also in pushing the abdominal viscera upwards. In hurried or laboured expirations the diaphragm is pushed more forcibly upwards by the muscles mentioned, and the ribs are pulled downwards, and the chest compressed, by the quadrati lumborum, serrati postici inferioresf , sacro-lumbales and longissimi dorsi muscles. MM. Beau and Maissiat J have described three kinds of ordinary respiratory move- ments : i. the abdominal, in which the abdo- minal walls chiefly act : 2. the costo-inferior, in which the movements chiefly take place in the lower ribs, from the seventh inclusive, downwards : 3. the costo-supsrior, in which the superior part of the chest is carried u[)- wards by the elevation of the superior ribs and the sternum. The first kind, or the ab- dominal type, is observed in infants up to the end of the third year in both sexes ; but after this period the costo-superior type in girls, and the costo-inferior and abdominal types in boys, generally prevail, and this difference becomes more marked as they advance in years. Almost all men, therefore, breathe by * Maissiat, in his Etudes de Physique Animale, and Beau and Maissiat in Ai-ch. Gener. de Me'd. tom. iii. p. 263. 1843. t Dr. Hutchinson informs us that the body is considerably shortened diu-ing violent expiration. (Op. cit. pp. 191, 192.) X Archiv. Gen. de Med. tom. xv. p. 399. 1842. 336 RESPIRATION. the lower part, and women by the upper part of their chest, and this independentk of the effects of particular articles of dress ! * This difference in the mode of respiration in the two sexes is, in general, maintained even in dyspnoea, unless it be very severe. As the costo-inferior and abdominal types of respi- ration would be impeded in the female when pregnant, the ordinary costo-superior type of respiration in the female has apparently a reference to that condition.-}- Valentin J, Dr. Hutchinson^, and Men- delssohn 11, have lately made experiments upon the force of the muscular movements of in- spiration and expiration. Those of Dr. Hutch- inson are much the most extensive, and are loOO in number. He found that the power of expiration is nearly one third stronger than that of inspiration ; and he states that whenever the expiratory are not stronger than the inspiratory muscles, that some dis- ease is present. He tested the force of the two classes of respiratory muscles by causing persons to make the most powerful efforts of which they were capable when breathing through the nose into an instrument con- structed for the purpose, and the subjects of experiment were taken from individuals of the male sex, following very different occu- pations. In examining the results of the whole experiments, and including all the thirteen classes of men subjected to expe- riment, the power of the inspiratory muscles is found greatest in men of o feet 9 inches in height, their inspiratory power being equal, on an average, to a column of 2'7o, and their expiratory power to 3*97 inches of mercury ; while in four of these classes, composed ge- nerally of active, efficient, and healthy indi- viduals, viz. Firemen, Metropolitan Police, Thames Police, and Royal Horse Guards, the inspiratory power of the men of 5 feet 7 inches was the greatest, being equal to 3'07 inches of mercury, and those of 5 feet 8 inches to 2 96 (nearly 3 inches). The aver- age power of the 5 feet 7 inches and 5 feet 8 inches men of all the thirteen classes was only 2"65 inches of mercury. The inspiratory power of twelve six-feet men in the first bat- talion of Grenadier Guards was only 1*92 inches, while that of thirty-one of the same * These observations of Beau and Maissiat upon the differences in the respiratory movements in males and females are confirmed by Dr. Hutchin- son (Op. cit. p. 195), and they were known so far to Boerhaave and Haller. t These authors also state that this difference in the respiratory^ movements of the two sexes have impressed upon the chest certain anatomical differ- ences ; for while the intercostal spaces at the upper part of the chest are larger in the female, those at the lower part are larger in the male ; and wliile the first rib is moA'able in the female, it is almost or entirely immovable in the male. X Lehrbuch der Phvsiologie des Menchen, band i. S. 524. 1844. § Journal of the Statistical Society of London, vol. vii. p. 193. 1844 ; and Medico-CMrurg. Trans- actions of London, vol. xxix. p. 197. 1846. II Der Mechanismus der Respiration und Circu- lation, S. 116—120. BerUn, 1845. height in the Blues (Life Guards) was 2-71 inches. He infers from these experiments that a healthy man of 5 feet 7 inches or 3 feet 8 inches, should elevate by inspiration 3 inches of mercury. The force of the expi- ratory muscles is more liable to be affected by the ordinary occupation of the individual than that of the inspiratory muscles, and therefore the state of the former is less to be relied upon in judging of the health of the individual than that of the latter.* The elas- ticity of the walls of the chest is, no doubt, one cause of the greater force of the expi- ratory over that of the inspiratory muscles. In inspiration the pressure of the elastic air in the lungs causes these organs to ex- pand, so as to keep their outer surface in contact with the inner surface of the dilating thorax ; and by this the air of the lungs be- comes rarified, and a quantity of fresh air rushes along the trachea and bronchial tubes to restore its equihbrium : in expiration, on the other hand, the lungs are compressed, and a portion of air is forced outward along the same passages. In these movements the lungs are not quite passive. The external surface of the lungs, and of the numerous lobes into which they may be divided, is covered with an elastic membrane, and this, conjoined with the weight of their tissues, must favour the expulsion of the air during expiration, and present a certain amount of resistance to its entrance during inspiration. -f- * Valentin's experiments upon the respiratory forces were performed upon six males between 1*8 and 32 years of age. In ordinary tranquil respira- tion the force of each of the acts of inspiration and expiration was equal to the weight of a column of mercur}- of from 4 to 10 millimetres (or from -1574 to -3937 of an English iach) ; in the least forcible respiration it ranged between 20, 35, and 4 33 0 16 216 34 1 17 95 35 0 18 181 36 1 19 70 37 0 20 510 38 0 21 120 39 1 22 136 41 1 23 41 24 220 Total 1714 25 16 From Mr. Hutchinson's table it would ap- pear that the majority of male adults breathe between 16 and 2-1: times per minute, and that of these a great number make 20 respirations per minute. + Accordin2 to Prevost and Dumas j, the ratio of the respirations to the pulsations of the heart is as 1 to 4. According to Mr. Hutchin- son §, "the prevailing numbers run as four beats of the heart to one respiration." Quetelet || states, that " it does not appear that there is * Medioo-Chirurgioal Transaotioiis of London, vol. xxix. p. 226. 1846. •I- The following results upon the fi^uency of the respiration in a state of rest hare been obtained by others ; but as these were made upon their oicn per- sons, thev possess only the value of individual cases. Dalton (Memoirs of the Literary and Philosophical Society of Manchester, 2nd series, voL iL p. 26, 1813) "foimd the number of his respirations to be 20 per minute : Thomson (System of Chemistry, voL iv. p. 604, 1820), to be 19 :" Sir H. Davy (Researches chiedv concerning Xitrous Oxide and its Eespira- tion, p. 434, 1800), to be 26 or 27 ; Magendie" (Com- pendium of Physiology, translated by Milligen, p. 390, 1831), to "be 15V E>iinglisson (Htmian Physio- logy, vol. ii.), to be 16 : and Allen and Pepys, on one of" themselves (Philos. Trans, of London for 18<."i8), to be 19. Menzies (Teutamen PhysioL Liaug. de Re- spiration e, 1790), fomid them to be 14 in the minute in the person on whom he experimented : Yierc>rdt (Article " Respiration " in Wagner's Handworterbuch der Physiologie, band ii. S. 834), in his own person, fotmd them on an average to be ll^^g when sitting, and the mind disengaged: while their maximum was 15, and their minimiun 9. Dr. Guy (Hc»oper*3 Tade-Mecmn, edited by Dr. Guy) ascertained that the respirations in his own person were 22 in a minute while standing. 19 when sitting, and 13 when in the recumbent position. X Vide Burdach's Traite' de Physiologie, traduit de FAllemand par Jourdan, torn. vii. p. 38. 1837. § Journal of the Statistical Society of London, vol. vii. p. 205. Ii Op. cit. RESPIRATION. 339 a determinate ratio between the pulsations and respirations ; however, in many indivi- duals, and I am of the number, it is as 1 to 4." Dr. C. Hooker* informs us that, from numerous careful observations, he has arrived at the conclusion, that the numerical relation between the beats of the heart and the respi- rations (except in infancy) is as I to 4^, and that any marked deviation from this relation indicates some mechanical or structural impe- diment to the free play of the lungs. Accord- ing to Burdachf, the same circumstances which diminish the frequency of one of these movements acts equally upon the other ; but it is proved by the recent observations of Dr. Guy, that these variations do not bear the same proportion to each other. In Dr. Guy's experiments J, the proportion between the respirations and the pulse has varied from 1 : 2*60 to 1 : 5*23 ; and whereas the pulse be- comes less frequent as the day advances, the respiration increases in frequency, so that there are 18 respirations in the evening for 17 in the morning. The chief cause of the varia- tion in the ratio of the respirations and the pulse "is the position of the body. Thus, for a pulse of 64, the proportion standing was 1 : 2-95 ; sitting, 1 : 3'35 ; and lying, 1 : 4-97. In the sitting posture, but from different fre- quencies of the pulse, it has varied from 1 : 2*61 to I : 5*00. The proportions morn- ing and evening for the same frequency of the pulse are about 1 : 3 60 and 1 : 3-40. The proportions which the respiration bears to the pulse decreases as the pulse increases. Thus, for a pulse of 54 the proportion was 1 ^ 3, for a pulse of 72 it was 1 : 4." Quantity of air drawn irito the lungs at each insj)iration, and expelled at each expiration ; and the quantity of air in the lungs at different times. — During ordinary respiration in a state of health, and when the body is at rest, a small quantity only of the air which the lungs can contain is exchanged by each act of inspiration and expiration. The average amount of air in the lungs in the state of ordinary respiration, may be considerably in- creased or diminished by forced inspirations and expirations, but the whole air contained in the lungs cannot be expelled by the most powerful action of the muscles of expiration. The quantity of air drawn into the lungs by each inspiration and again expelled by expira^- tion, in the state of ordinary aspiration, not only varies in different individuals, but in the same individual in different conditions of the body, so that the results obtained by physio- logists on this point must necessarily be dis- similar, and the more especially as the greater number of these have experimented only upon a single, or a very limited number of indivi- duals. The difficulty of ascertaining the ave- rage quantity of air exhaled at an ordinary * Boston Medical and Surgical Journal for 1838, Vide also British and Foreign Medical Review, vol. vii. p. 2G3. t Op. cit. p. 39. X Hooper's Vade-Mecum, edited bv Dr. Guy, pp. 131, 132. 184G. expiration, and the great range that occurs in this respect, may be judged of by the state- ment of Vierordt, that the variation in his own person is as great as 1 : 4"75.* The pro- bable average quantity of air drawn into the lungs at each inspiration even in healthy indi- viduals, at different ages and in different states of the body and of the physical conditions under which it may be placed, can only be ascertained by the performance of a much more extended series of experiments than we at present possess ; and the ascertainment of the causes which determine these variations from the average quantity will be still more difficult, and of still more importance. All such experiments are liable to many sources of fallacy, both from imperfections in the instruments used in conducting them, and from the muscular movements of respiration being unwittingly influenced by the attention of the persons experimented upon being fixed upon these movements j but the later experi-> ments on this point are more trust-worthy than the earlier, as the instruments employed are better suited for the purpose, and by fre^. quently repeating the experiment on the same persons, they at last become accustomed to the artificial circumstances under which they are placed, and they breathe more naturally. Herbst, from his experiments, concluded, that a healthy adult of average size should in an ordinary inspiration inhale from 20 to 25 Parisian cubic inches (24*211 to 30-263 English cubic inches), and exhale the same quantity in expiration; while an individual of a feebler constitution of body should inhale from 16 to 18 Parisian cubic inches (19*368 to 21*789 English cubic incites). f Valentin gives as the result of his experiments upon seven males between 17^ and 33 years of age, that the quantity of air expired in ordinary up to a somewhat quickened respiration, ranges between 239*3 and 1567*7 cubic centimetres (14*603 and 95*672 English cubic inches), the average of which was 655*11 c. c. (40*081 English cubic inches).^ Vierordt §, in re- peated experiments upon himself, ascertained that at each expiration, when in a state of rest, he ex[)elled from the lungs on an average 507 cubic centimetres (30*940 English cubic inches), and that the average of the five high- est values was 699 c. c. (42*657 E. c. inches), and of the lowest 177 c. c. (10*801 E. c. inches). II Bourgery, from experiments upon * "Wagner's Hand-vvorterbuch der Physiologie, band ii. s. 836. f IMeckel's Archiv fiir Anatomie und Physio- logie, band xiii. S. 83. 1828. X Lehrbuch der Physiologie,! band i. S. 538. These calculations of Valentin rest on the supposition that the expired air is fully saturated with moisture — a supposition invahdated by the experiments of Moleschott. § TS^agner's Handworterbuch der Physiologie, band ii. S. 835. Vierordt elsewhere states that he is. of the middle height, and has no particularly roomy chest, was 59 kilogrammes in weight and 25 years of age Avhen he performed his experiments. II The following estimates have been drawn from a limited number of experiments upon a single individual, or upon a very small number of iu- z 2 340 RESPIRATION. fifty males and twenty females*, with the view of ascertaining the relation between the inti- mate anatomical structure of the lungs, and the functional capacity of these organs in the 'two sexes, concludes that the volume of air required by an individual in ordinary respira- tion augments gradually with the age, being least in youth (from 5 to 15 years), in conse- quence of the extreme vascularity of the lungs ; increased from 15 to 30 years of age, in consequence of the proportional diminution in the closeness of the pulmonary capillary network of blood vessels ; and to a much greater amount in old age, in consequence of the more rapid diminution of the extent of the respiratory membrane, which begins to take place after the lungs have arrived at their full development, or the age of 30. It is obvious that we are not yet in posses- sion of data to enable us to venture upon an estimate of the average quantity of air in- spired and expired at an ordinary respiration, when the body is at rest and the mind undis- turbed, at different periods of hfe, in the two sexes, and in different physical configurations of body. It is equally apparent that this is liable to considerable variation, and that the different results obtained by most experi- menters,— setting aside those where an obvi- ously faulty method was pursued, — depends as much upon the inherent differences in the extent of the respiratory movements in the individuals experimented upon, as upon errors in the mode of experimenting, and that the chief error committed by some of them consists in deducing averages from the few and insufficient experiments performed by themselves, and casting doubts upon the results obtained by others, simply because di%iduals, and are therefore of little value in enabling us to ascertain the average quantity of air taken into the lungs and again expelled in ordinary respiration. Besides, some of these experiments are liable to ob\'ious objections. Borelli (De Motu Animalium, Pars Secunda, p. 118. Lugdani, 1685) who appears to have been the first who attempted to ascertain this by experiment, estimates it at 15 cubic inches. Turin (Diss. p. 41, 42, as quoted by Haller), fi-om experiments on his own person, at 40 cubic inches ; and this is the estimate also formed by Menzies (op. cit. p. 28,) from his experiments. GoodwA'n (The Connexion of Life "\\ith Respiration, &c., p. 36. 1788), from experiments on three individuals, esti- mates the quantity inspired at 12 cubic inches, which he supposes to be increased to 14 in the lungs by the increase of temperature. Sir H. Daw (Researches Chemical and Philosophical, &c., p\ 4.33, 1800) informs us that he threw out of his lungs at each ordinary inspiration nearly 1 3 cubic inches ; ]Mr, Abernethy (Surgical and Physiological Essays, Part II. p. 142', 1793), that he inspired 12 cubic inches ; Dalton (Memoirs of the Literary and Philosophi- cal Society of Manchester, 2nd Series, vol. ii. p. 26), also from experiments on his own person, esti- mates an ordinary inspiration at 30 cubic inches ; Allen and Pepys' (London Phil. Trans, for 1808), from experiments on one individual, at 16^ cubic inches; and Thomson (Animal Chemistry, p. 612. 1843) estimates his own inspirations at 16 cubic inches. * Archiv. General, de Med. 4^ Serie, torn. i. p. 875, 1843, and Comptes Rendus, 23 Janvier, p. 182. 1843. they do not accord with their own. It also necessarily follows that we are not in a posi- tion to form an estimate of the average quan- tity of air which passes out and in from the lungs in twenty-four hours in ordinary respi- ration. Vierordt*, from experiments on his own person, calculates that he respires 603-t cub. cent. (368'074' English c. inches) of atmospheric air in one minute, or 8,688,960 cub. cent. (o30,026'560 Eng. c. in.) in the twenty-four hours. As, however, the respi- ration is rendered more energetic by speaking, walking, &c., any estimate drawn, as this by Vierordt is, from observations made when the body was in a state of rest, will be, as he was aware, too low ; and proceeding on some of the results of Scharling's experiments, he makes allowances for this increase, and esti- mates the quantity of air respired in the twen«:y-four hours at 624,087'401 Enghsh cubic inches. Valentin -j- calculates that in his own person, after making allowances for temperature and watery vapour, he respires 469'97o5 litres (28681 1948 English cubic inches) in an hour, and 688,348-6761 Eng. cubic inches, or nearly 398.| cubic feet of atmospheric air in the twenty-four hours.J The quantity of air drawn into the lungs during quickened or forced inspiration, and again expelled during expiration, also varies very considerably in different individuals of the same age. Sir H. Davy§, in many ex- periments upon himself, ascertained that at a temperature from 58° to 62° Fahr. he threw out of his lungs by a full forced expiration, Cubic Inches. After a full voluntary inspiration, from 189 to 191 After a natural inspiration, from 78 — 79 After a natural expiration, from 67 — 68 So that, making corrections for temperature, he calculates that his lungs, in a state of vo- luntary or forced inspiration, contained about 254 cubic inches ; in a state of natural in- * Op. cit. pp. 856, 857. t Op. cit. p. 570. The effects of exercise, diges- tion, &c., are included in this estimate. X Mr. Coathupe (London and Edinburgh Phil. Magaz. vol. xiv. p. 401, 1839), from experiments on his ovn\ person in a state of rest, estimates the number of respirations at 20 in the minute, the average bulk of each respiration at 16 cubic inches, and the quantity of air that passes through the lungs in 24 hours', at 460,800 cubic inches, or 266-66 cubic feet. Mr. Coathupe's estimate agrees pretty closely ■^^^th that of Dumas (Statique Chimique des Etres' Organises, 3" edit. p. 87), also formed from experiments on his ovra. person, in a state of rest. The estimate of the quantity of air that passes through the lungs, given by Bostock (System of Physiology, p. 321, 1836) is "in all probability above the" average. He proceeds on the supposition that in ordinary respii-ation a man respires 40 cubic inches of a'ir 20 times in a minute, so that he makes the quantity respired in the 24 hours, 1,152,000 cubic inches or about 666^ cubic feet. It is probable that between 25 and 30 cubic inches of air for each ordi- nary inspiration will be found to be near the average in an adult male when in a state of rest. § Researches Chemical and Philosophical, &c., p. 410. 1800. RESPIRATION. 341 spiration about 135; in a state of natural expiration about 118 ; and in a state of forced expiration 41 .* Goodw vn-|-, in his experiments on the capacity of the lungs upon four indi- viduals after a natural death, found the resi- dual air in the lungs to vary from 90 to 125 cubic inches, giving an average of 109, and as the chest, after a natural death, may be re- garded as in a state of natural or ordinary expiration, this result differs very little from that of Davy. Allen and PepysJ, in one experiment on the capacity of the lungs in a middle-sized man after death, also obtained a little more than 100 cubic inches of residual air. Vierordt^ supposes that the residual air in the lungs, after the deepest expiration, is about 600 cub. cent. (36-600 Eng. cub. in.), which differs but little from the estimate of Davy. Herbst || made experiments upon 1 1 males, between 16 and 30 years of age, with the view of ascertaining the quantity of air drawn into the lungs in forced inspiration. The smallest quantity observed was in a Jew aged 22, of small stature, and feeble muscular sys- tem. He inspired between 60 and 70 Parisian cubic inches (between 72'635 and 84*738 Eng. cub. in.) after an ordinarv expiration ; be- tween 102 and 118 (123-476 and 142-844 Eng. cub. in.) after a strong expiration ; and 120 (145-266 Eng. cub. in.) after the strong- est expiration. The largest quantity inspired was by a young man of 25 years, of middle height with a broad chest and large and powerful muscles, who inspired by a forced inspiration, about 169^ English cubic inches, without any previous voluntary expiration; about 290|- after a strong expiration ; and about 290h or 295^ after the strongest ex- piration. A young man of 23 years of age, 6 feet high, with broad chest and large mus- cles, inspired, without any previous voluntary expiration, 121 English cubic inches, and 280-72 after the fullest expiration. The quan- tities of air drawn into the lungs in forced inspiration in the other eight males, were in- termediate between the highest and lowest mentioned above, and the average was about 202 English cubic inches. Herbst also sa- tisfied himself that the lungs of females have a considerably smaller capacity for air than those of males. He states that robust fe- males, about the age of 30, may inspire with- out a previous voluntary expiration, 72^ English cubic inches, after an ordinary ex- * Sir H. DavA- states that this capacity is most probably below the medium, as his chest was nar- row. t Op. cit. p. 26. J Philos. Trans, of London, 1809. § Op. cit. p. 892. li Op. cit. p. 98. % Herbst foimd that a boy of 15 years inspired 116-16 English cubic inches fifter a strong expira- tion, and expired the same quantity after a full in- spiration. Another boy of 13 years,' but of the size of one of 15, likewise 'expired' 116-16, while a boy of 11 years inspired withoiit a pre^-ious expiration, 36-30 ; after a strong expiration he inspired 72*60 English cubic inches,"aud expired the same quantity after a full inspiration. piration nearly 109, and after the strongest expiration, from about 157^ to 174^ English cubic inches.* Herbst had an opportunity, in two of these experiments on males, of ascertaining the effects of tight clothing on the extent of the respiratory movements. One individual who inspired 128 and another 116-16 English cubic inches, without a pre- vious expiration after the clothes were loos- ened, could before this only inspire 96-80 and 60.V English cubic inches, t The most extensive experiments by far, made with the view of ascertaining the quantity of air which can "be thrown out of the lungs b}' forced expiration, after the deepest inspiration, are those of Mr. Hutchinson. ^ These experi- ments were performed upon 1923 males, and they were made to breathe into an instrument constructed for the purpose, and which he has called a spirometer. He has inferred from the data he has collected on this point, the rule, that " for every inch of height (from 5 feet to 6) 8 additional cubic inches of air at 60° Fahr. ai-e given out by a forced ex- piration ;" so that he believes that from the height alone of an adult male, he can tell what quantity of air he should breathe to constitute him healthy, and that this method may be turned to important practical appli- cation in ascertaining disease of the lungs, * Bourgen* (op. cit.) states, that in well formed and healthy incli\iduals, a man at 30 ^^ill, by a forced inspiration, draw into the lungs 2-50 to 4-30 litres (or 152-567 to 262-416 English cubic inches), and a woman from 1-10 to 2-20 litres (or 67-129 to 134-259 English cubic inches), and has inferred from his experiments, that at the same age the amount of forced respiration of the male doubles that of the female, and this con- clusion accords with the results of Mr. Thackrah (The Effects of Arts, Trades, and Professions, &c., on Health and Longe^-ity, 2nd edit. p. 181, 1832), who states that " extensive examination shows us that, while healthy men exhale by the pulmometer 200 cubic inches and upwards, women rarely exceed 100, and often do not reach that amount." Mr. Thackrah supposes that this diflerence is duC; to a considerable extent, to tight lacing by females. t The condition of the stomach as to fulness, also affects the extent of the respiratory muscular movements. Mr. Hutchinson says, " I have found a dinner diminish the \-ital capacity (by which he means the greatest volimtary expiration foUoAv-ing the deepest inspiration) to the extent of 12 and even 20 cubic inches." The position of the body has also, according to Mr. Hutchinson (opus cit. p. 197), a considerable effect upon the vital capacity of the chest. In experiments upon himself he found that when standing he could throw out 260 cubic inches ; sitting, 255 ; and when recumbent (supine), 230, (prone) 220, so that position effected a difference of 40 cubic inches. In a fit of dyspnoea a person can breathe easier in the erect or sitting than in the re- cumbent postiu-e, as the dorsal movements that attend difficult respiration, are freer in the former than in the latter position. X Joiu-nal of the Statistical Society of London, vol. vii. 1844, and ^Nledico-Chirurgical Transact tious of London, vol. xxix. p. 137. 1846. The memoir in the last publication contains a more extensive series of experiments than that in the former. These researches would require to be still farther extended upon both sexes at the various periods of life, and imder varied circumstances, be- fore they can jield all the information on thii; subject that is desirable. z 3 343 RESPIRATIOX. under circumstances where the ordinary me- thods fail. Mr. Hutchinson has given the following table to show the quantity of air expelled by the strongest expiration after the deepest inspiration for every inch of height between 5 and 6 feet, as ascertained by actual experiment (column 1) by his spirometer, and as calculated according to the rule mentioned above (column 2). Height. From Observation. Regular Progression. ft. in. ft. in. cub. in. cub. in. 5 0 to 5 1 174 174 5 1—52 177 182 5 2 — 53 189 190 5 3 — 54 193 198 5 4-^55 201 2i36 5 5 — 5 6 214 214 5 6 — 5 7 229 222 5 7 — 5 8 228 23<3 5 8 — 59 237 238 5 9 — 5 10 246 246 5 10 — 5 11 247 254 5 11 — 6 0 259 262* Mr. Hutchinson has found that two other conditions of the body besides the height, regulate the quantity of air that passes to and from the lungs in forced voluntary respi- ration, and these are age and weight. He states that weight doe^ not atFect the respira- tory power of an individual of any height between 5 feet 1 inch and o feet 1 1 inches until it has increased 7 per cent, above the average weight of the body in persons of that height, but beyond this it diminishes in the relation of 1 cubic inch per pound for the next .35 pounds— the limit of the calculation. In males of the same height the respiratory power is increased from 15 up to 35 \ears of age, but from So to 65 years it decreases nearly li cubic inch for each year.f Bourgery * Med.-Chir. Trans, vol. xxix. p. 237. Experi- ments to ascertain the quantity of air that may be inspired or expired in forced respiration have also been perfonned by Hales (Statical Essays, vol. i. p. 243), Jiirin, Menzies, Goodw%-n, Dr. Bostock (Sys- tem of Physiology, p. 316. 183*6), Dalton (Opus cit, p. 26), Thomson (Animal Chemistry-, p. 610. 1843), Valentin (Opus cit. p. 540), and Thackrah (The Effects of Arts, Trades, and Professions, &c. on Health and LongeAity, 2nd edit. pp. 27, 30, 64, 76, 98, 181, and 182). These experunents, however, are neither sufficiently numerous — several of them hav- ing been performed on a single indi%'idual only, — nor are they accompanied "with the details necessary to enable us to contrast them with those of Mr. Hutchinson ; but the results obtained in the greater number of these do not differ much from those of IMr. Hutchinson Ujion men of middle stature. Va- lentin experimented on six males, and his estimates rest on the questionable supposition that the ex- pired air is fiilly satiu-ated vrith moisture. Thom- son experimented on 11 males and 1 female, from 14 to 33 years of age : and ]\Ir. Thackrah's experi- ments were considerably more extensive, and were made on individuals of different trades and pro- fessions. t Mr. Hutchinson has not observed any direct relation between the circumference of the chest and the respiratory power or Avhat he terms the vital capacity. According to the experiments of Herbst concludes from his experiments already re- ferred to, that the measure of respiration (by which he apparently means the quantity of air which may be drawn into the lungs by a forced inspiration) is greater the younger and thinner the person is ; that its maximum in both sexes occurs at the age of 30 ; that the relation of a forced and ordinary res[)iration diminishes with the age of the individual, being, he says, from 1 to 12 at three years of age, as I to 10 at fifteen, as I to 9 at'twenty, as 1 to 3 at sixty, and as 1 to ^ or -i- at eighty years ; whence it follows that in youth there is an immense respiratory power in reserve for any violent exertion, while in old age the individual under such circumstances is at once out of breath.* Changes upon the atmospheric air in respi- ration.— One of the most obvious changes, under ordinary circumstances, upon the air that enters the lungs in respiration is an increase of its temperature, and consequently an augmentation of its bulk. As a quantity of water is readily supplied by the fluid secre- tions of the inner surface of the air-passases, and by the blood in the pulmonary capillary blood-vessels, this augmentation of the tem- perature of the air is also necessarily attended by an increase of its watery vapour, and con- sequently by an additional increase in its bulk and elasticity. The expired air, therefore, contains more caloric, more watery vapour, is more elastic, and is of less specific gra%-ity than the inspired air. Valentin performed 12 experiments on his own person by breathing through an apparatus invented by Brunner and himself, to ascertain the temperature of the expired air, and he obtained the following results. In breathing atmospheric air of a temperature varying from 8°-o to 33°'o Reau- mur (51°-12o to lO^T'^-ST.S Fah.), he observed a difference of l°-7o R. (3=-937 F.) in the temperature of the expired air, M'hile breath- ing in the lowest temperature, \\z. 51^'] 25 F., the temperature of the expired air was 96°* 687 F., and was warmer than the inspired air by 45° •562 F. ; and when breathing in the highest temperatm'e the expired was colder (Opus cit. p. 104), and Mr. Hutchinson, the mode of determining the quantity of air which the lungs are capable of containing during life in any parti- cidar case, by measuring after death the quantity of air which can be thro^^^l into them by inflation, is fallacious. This is probably chiefly due to the congestion of the depending parts of the hmgs by blood, so fi-equently foimd after death. Both Herbst and Mr. Hutchinson have performed experiments to show the extent to which the quantity of air in forced respiration is diminished in phthisis. * Among the proofs of these conclusions, ad- vanced by Bourgery, it is stated by him that the measure of respiration of a boy of 15 years of age is 2 litres (122-054 Eng. cubic inches), and a man of 80 years 1-35 litre (82'386 Eng. cubic inches) : that while a boy of 10 years and a man of 80 inspire by a forced inspiration the same quantity of air, viz. 1-35 Litre, yet the ordinary respiration of the former is only 1 decilitre (6402 Eng. cub. in.), while that of the latter is 9 decilitres (54-918 Eng. cub. in.) ; so that ynxh. a mass three times smaller, the child possesses an energy of hematose eight times greater. RESPIRATION. 343 than the inspired air by 6°'75 F. In the last experiment, though the inspired air was 7°'875 F. warmer than the internal tempera- ture of the body, the expired air was only about 1°*125 F. warmer than what it is when air of the ordinary temperature is breathed. The average temperature of the expired air is, according to Valentin, 99°'5 F. when breath- ing in an atmosphere of moderate tempera- ture.* According to his calculations, when a person breathes 100 cubic centimeters of atmospheric air at the temperature of 60° F., their bulk is increased to 107-87975 cubic centimeters when raised to the temperature of 99*5 F. in the lungs, since the expansive co-efficient of atmospheric air is 0 3C65. As the expired air, however, contains ^'^ per cent, of carbonic acid gas, and as the ex- pansive co-efficient of this last gas is 0'369087 the expansion of the expired air will differ slightly from what it would be were it com- posed of oxygen and nitrogen only, and will be 107*882197 cubic centimeters.f It is difficult to obtain an accurate estimate of the quantity of watery vapour that escapes from the body along with the expired air. Were the inspired and expired air always fully saturated with moisture, and were their quan- tities, barometric pressure, and relative tem- perature accurately ascertained, the absolute and relative quantities of watery vapour which they contain could be calculated by certain algebraic formulae. The atmospheric air which we breathe is sometimes saturated with moisture, more frequently the dew-'point, or that at which the precipitation of the atmo- spheric moisture can occur, is considerably below the temperature of the air, and the number of thermometric degrees between the actual temperature of the air and the dew- point shows the degree of dryness in the air, or in other words how much it is below the point of saturation with moisture. J The * Moleschott (Holljindiselie Beitrage zu den anatomischen und physiologischen Wissenschaften, band i. heft i. S. 86. Utrecht und Dusseldorf, 1846) has more lately made experiments on the temperature of the air in the hack part of the mouth,, and ascertained that in a range of temperature in the external air to the extent of 12° -6 F. that there was scarcely any difference in the temper- ature of the expired air. In 26 experiments, — three of which were upon women, — upon indivi- duals chiefly from 19 to 43 years of age, he found the average temperature of the expired air to be nearly 98° -6 F. The longer or shorter time which the inspired air remains in the lungs will modify the results in such experiments. t Opus cit. X According to the calculations made by the late Professor Daniell (Elements of Meteorology, vol. ii. p. 316. London, 1845) from meteorological tables,, kept for 17 years consecutively, the mean temper- ature of London is 490-54 F., while the mean dew- point is 440-31, giving 50-59 upon the thermometric scale, and 827 upon the hygrometric scale, as the degree of drjmess. The mean elastic force of this watery vapour is, he says, -342 of an inch of mercury, and a cubic foot contains 3-806 grains of moisture. The greatest degree of dr>niess was 49^ F., or the least degree of moisture when the hygrometric scale was 235. According to Dalton's observations (Man- chester Memoirs, 2nd series, vol. ii.) the medium of loss of watery vapour by the lungs will evi- dently be regulated by the temperature of the inspired air, the quantity of watery vapour it holds in solution, the volume of air inspired, and the length of time it remains in the lungs. The lower the temperature of the inspired air, the less it apprc^aches to the point of sa- turation with moisture, and the greater its volume, the greater will be the loss of watery vapour by the lungs. When the respirations are more rapid, and the sojourn of the air within the lungs is short, the same volume of expired air will probably contain less water in solution, than when its sojourn there is more prolonged, but the more frequent renewal of the air within the lungs will be more than sufficient to compensate for this. The most correct and trust-worthy expe- riments to ascertain by the direct method the quantity of watery vapour in the expired air are those of Valentin and Brunner.* These experiments were performed upon seven males between the ages of 17^- and 33 years, and the maximum of watery vapour exhaled was 13156*323 Troy grains in the 24 hours; the minimum 4511*374 grains, and the average 7819*222 grains. The quantity of watery vapour in the expired air within a given tin)e varied in the same individual ;. and in one exp^iment it was increased after drinking. In these experiments the entire quantity of water in the expired air was ascertained, so that the actual quantity given off by the fluids of the body must have been less than this ; and Valentin calculates that if a person breathes atmospheric air saturated with moisture, at the temperature of 60° Fahr., and if the expired air be at the temperature of 99°*5 Fahr., and also saturated with moisture, about f of the watery vapour contained in the expired air will be lurnished by the fluids of the body.f, We have seen that aqueous vapour in this climate (that of Manches- ter) may be estimated at -30 5f an inch of mercury due to the temperature of 44^' ,F. This vapour, he says, is increased by the temperature of 98° in the lungs from -30 to 1-74 inch of mercury, being an increase of 1-44 inch ; but it will only be equal in weight to air of 1 inch of force, as the specific gravity of vapour is less than that of air in the pro- partiou of 7 to 10. Valentin calculates (Opus cit. p. 533) that 100 cubic centimeters of dry air under a barometric pressure of 29-922 English inches, raised to the tempei-ature of 99-5 F., and saturated with moisture, would be expanded to 106-488 cubic centi- metres. * Opus cit. p. 536. Lavoisier has given different estimates of the quantity of watery vapour in the expired air in his papers on respiration and trans- piration in the Memoires de I'Academie des Sciences. Hales, Menzies, and Abemethy, from experiments on themselves, and employing different kinds of ap- paratus, all more or less imperfectly suited for the purpose, have respectively estimated it at 9792 grs. or about 20 oz., 2880 grs. or about 6 oz., 4320 grs. or about 9 oz. Dalton and Thomson, from calculations based upon the relative quantities of watery vapour required to saturate the inspired and expired air, have estimated it respectively at 1*55 or nearly l^lb. Troy or 8640 grs., and at 19 oz. t"^ Opus cit. p. 533. Vierordt (Physiologie des Ath- mens, &c. S. 155. 1845) calculates from the quantity z 4 344 RESPIRATION. several of the calculations of the amount of the watery vajiour exhaled from the lungs proceed on the supposition that the expired air is saturated with moisture, but this has not been substantiated by the only experiments made with the view of deter- mining this point. In Moleschott's experi- ments, the amount of water held in solution varied. In five out of seven experiments the watery vapour in the expired air was appre- ciably less than what is sufficient to saturate air of the same temperature, while in one experiment it was saturated. On taking the average difference in the seven experiments performed, as much as possible under similar circumstances, between the actual quantity of moisture in the expired air, and in air of the same temperature saturated with moisture, he found that 2420 cub. cent. (147-620 Eng. cub- inches) of the expired air would require a quantity of watery vapour additional to that already existing in it equal to 10 millegrammes ("150 Eng. Troy grains) to saturate it. From these experiments he concludes "that in the greater number of instances the expired air in man is not saturated with watery vajiour, but sometimes such a saturation occurs."* Magendie observed, in experiments on dogs, that the escape of an increased quantity of watery vapour from the mouth follows the injection of water into the veins, caused, as he supposes, by the transpiration from the lungs being considerably increased.f Animal mattei's in quantities too minute to be subjected to analysis are also exhaled from the lungs, and escape along with the expired vapour. The condensed vapour from the lungs, when collected in a vessel, and kept for some days, putrefies, and emits an ammoniacal smell.;}: We are also often sensible of the escape of different substances, previously taken into the sto- mach, along with the expired air, by their smell ; and the experiments of Nysten §, of air respired by himself in a state of rest, supposing the temperature of the expired air to be 980-6 Fahr., and saturated ^\ith. moisture, the temperature of the inspired air to be 570-2 F., and containing only its average quantity of moisture, that the quantity of water in the expired air ^-ill amount in the '24 hours to 55oo-880 Troy grains, of which, on an average, 4953-993 grains may be allowed for the loss of water from the inner surtace of the lungs and air passages, and 601-887 grains for the quantity previously con- tained in tiie inspired air. As, however, the body is not at rest during a considerable part of the "24 hours, the loss of watery vapour must be greater than this. * Hollandische Beitrage zu den anatomischen und physiologischen Wisseuschaften, band i. S. 96. 1846. t Compendium of Phvsiologv, translated by Mil- ligan, p. 395. 1831. X Valentin and Brunner (Opus cit. pp. 571, 572), in their experiments on the human species, detected the presence of a minute quantity of organic matter in the expired air. This was ascertained by the sulphuric acid, through -which the expired air was made to pass, becoming red. Marchand (Journal fiir praktische Chemie, von Erdman imd Marchand, band xxxiii. S. 129. 1844), in his experiments on frogs, also observed this. § Recherches de Physiologie, &c. p. 145. Magendie*, Tiedemannf, and others, prove that various organic and mineral substances, when injected into the veins, escape in part by exhalation from the lungs. If the inspired air, during its sojourn in the lungs, becomes increased in bulk from an increase in ten-iperature and an addition of watery vapour, it suffers a small diminution from the absorption of part of its constituent gases. The older experimenters observed a diminution in the air respired, but as they experimented with imperfect apparatus, and transmitted the expired air through water which would absorb part of the carbonic acid gas, little confidence is to be placed in their results. J There can be no doubt that a greater amount of oxygen disappears from the inspired air than what is sufficient for the formation of the quantity of carbonic acid gas in the expired air, and that there is a slight diminution in the bulk of the expired air from this cause ; but we cannot speak so decidedly regarding any changes in the quan- tity of the nitrogen. Provencal and Hum- boldt §, in their experiments on the respi- ration of fishes, and J>pallanzani ||, in his experiments on snails, observed an absorption of azote : while Jurinel and Xysten**, in their experiments on the human species, and Ber- tholletf-f-, Despretzjj, Dulong§§, and Mar- tignyll II, in their experiments on warm-blooded animals, and TreviranusTT in his experiments on the cold-blooded animals, observed an exhalation of azote. Dr. W.F.Edwards***, in * Opus cit. t Zeitschrift fiir Physiologie, band V. 1835. This paper is translated in the British and Foreign Quar- terly Review, vol. i. p. 241. Tiedemann, in this paper, has given an account of all the experiments previously performed on this point by others. X GoodAv^-n (Opus cit. p. 51), Plafi" (Nicholson's Journal of Natural Philosophy, vol. xii. p. 249. 1805), Dr. Alex. Henderson (Nicholson's Joimial, vol. Aiii. p. 40), and Sir H. Davy (opus cit.), in their experiments on the human species, observed a dimi- nution in variable proportions in the respired air ; and Henderson, Plafl', and DaA^-, supposed that part of this diminution was caused by the absorption of nitrogen at the lungs. § Me'm. de la Societe d'ArcueU, [torn. ii. p. 388. 1809. II Memoire sur la Respiration, traduit par Sene- bier, pp. 162, 184, and 230. 1803. An absorption of azote was not imiformly observed by Spallanzani. ^ Me'moire couronne en 1787, par la Socie'te Rovale de Me'decine, as quoted bv Nvsten. ** Opus cit. p. 186. ft INIe'm. de la Societe d'Arcueil, torn. ii. p. 459. XX Annales de Chimie et de Physique, torn. xx\i. p. 337. 1824.' §§ Maaendie's Journal de Phvsiologie, 'torn. iii. p. 4b. 1823. nil Magendie's Journal, torn. x. p, 337. 1824. Zeitschrift fiir Physiologie, band iv. Trevi- ranus says, " in some of my experiments there was more azote than carbonic acid exhaled, and this not only in the avertebrata, but also in the frog." p. 33. *** De rinfluence des Ascens Phvsiques sur la Tie, p. 420. Tableaux 63, 64, aiid 65. 1824. Dr. Edwards concludes from his experiments that there is both a constant exhalation and absorption of azote at the lungs, and that these two actions are sometimes equal, while at other times the one preponderates over the other. RESPIRATION. 345 his experiments upon warm-blooded animals and reptiles, found that in some cases the quantity of azote in the air respired was increased, in others diminished, while in others it remained unchanged ; but these changes in the quantity of azote did not equal the difference between the amount of oxygen absorbed and of carbonic acid exhaled. La- voisier and Seguin*, Allen and Pepysf, Va- lentin and BrunnerJ, and Dr. Thomson^, in their experiments on the respiration in the human species, detected no change upon the quantity of azote.]! Boussingault t, by a series of comparative analyses of the aliments consumed, and of the excrements in a turtle- dove, arrived at the conclusion by this in- direct method of research that azote was exhaled. Marchand**, in his carefully-conducted ex- periments on frogs, detected a quantity of ammonia in the tube of his apparatus, con- taining the concentrated sulphuric acid, and concludes that nitrogen in this combination is exhaled from the lungs and skin. From a review of all the experiments upon the nitrogen of the respired air, we perceive that though the evidence preponderates in favour of the exhalation of a small quantity of nitrogen from the lungs ff, yet that it is not sufficiently conclusive to justify us in stating that its operation is constant. It appears, * Mem. de I'Academie Royale for 1789, p. 574. f Opus cit. X Opus cit. § Animal Chemistry, p. 612. 1843. Dr. Thom- son says, in experimenting upon animals placed in vessels in which the air was renewed during the experiment, no diminution of the volume of air took place, but the case was very dilFerei^ when the animal Avas obliged to breath confined air. Nysten (Opus cit. p. 230) observed an evolution of azote in the hmuan species, both in a state of health and disease, when the same air was breathed several times. Marchand, on the other hand (Jovirnal fiir praktische Chemie, band xxxiii. S. 166), from his experiments on frogs placed in close vessels, con- cludes that it is exceedingly probable, if not certain, that, under this condition, these animals absorb part of the azote of the atmospheric air. II Vierordt remarks upon Valentin and Brunner's experiments, and the same observation applies to to the others on the human species, that the evolu- tion of a minute quantity of nitrogen, not readily detected during the short time each of these experi- ments was carried on, might amount to a notable quantity in the 24 hours. ^ Annales de Chimie et de Physique, tom. xi. p. 433. 1844. In taking the mean of the result of his experiments, he found a turtle-dove, weighing 2885-971 English Troy grains, evolved in 24 hours from the lungs 288-697 grains of carbonic acid gas, and 2-469 grs. of azote, or in volume 576-155 English cubic inches of carbonic acid and 7-689 cubic inches of azote, — a considerably smaller quantity than was obtained by Dulong and Despretz in their experi- ments by the direct method. This quantity of azote, according to Boussingault, constitutes the one-third of the whole of this substance which entered into the composition of the aliment of the pigeon. ** Opus cit. ft It must, however, be remembered that in the great majority and in the most trust- worthy of these experiments in favour of the increase of the nitrogen, the exhalations from the skin were luixed with those from the lungs. however, from the evidence adduced, that the nitrogen in the expired air is at least frequently increased in quantity in ordi- nary respiration, but not to the extent of affecting materially the percentage of this gas in the respired air.* Valentin and Brunner, in their carefully conducted experiments, could detect no traces of hydrogen, carbonic oxide, or carburetted hydrogen, in the expired air. By far the most im[)ortant chemical change the atmospheric air undergoes during its so- journ in the lungs, is a diminution in the quantity of its oxygen and an increase of its carbonic acid gas ; and it may be safely af- firmed that all the other changes in the respired air are of trivial importance in the function of respiration, when compared with this. There can be no doubt that the con- clusion drawn by Allen and Pepys from their experiments, that the amount of oxygen which disappears from the inspired air is exactly equal to the quantity required to form the carbonic acid that a[)pears in the expired air, is incorrect ; for all the latest and most accurate experiments have confirmed the general accuracy of the results obtained by Lavoisier and Davy on this point, and have satisfactorily determined that a larger quantity of oxygen disappears from the inspired air than what is sufficient to form the carbonic acid gas present in the expired air. Percentage and absolute quantiti/ of carhonic acid gas in the expired air, — The results of the earlier experimenters on this point are of so little value that we need not refer to them. The following results have been obtained by some of the later experimenters : — QUANTITY OF CARBONIC ACID GAS IN THE 100 PARTS OF THE EXPIRED AIR ESTIMATED BY VOLUME. Average. Max. Min. Difference between Maximum and Minimum. Prout Coathupe Brunner & \ Valentin j Vierordt Thomson 3- 45 4- 02 4-380 4-334 4-16 4- 10 7-98 5- 495 6- 220 7- 16 3-30 1-91 3-299 3-358 1-71 •80 t 6-07 1 2-196 § 2-86 II 5-45 t * Even supposing the nitrogen of the respired air to remain unaltered in quantity, yet as the quantity of oxygen absorbed is somewhat greater than what is necessary to form the carbonic acid exhaled along with the expired air, the percentage of the nitrogen in the inspii-ed air will be slightly greater than in the expired air when estimated by volume. t Thomson's Annals of Philosophy, vol. ii. p. 333. 1813. In some subsequent experiments by I'rout (same Avork, vol. iv. p. 331) the range in the quan- tity of carbonic acid gas in the expired air was be- tween 2-80 and 4-70, the minimum number occurring once only, and while he was sleepy. Prout's expe- riments were performed upon himself, and at eveiy hour of the day and night. X London, Edinburgh, and Dublin Philosophical aiagazine, vol. xiv. p. 401. 1839. These experi- 346 RESPIRATION. The results obtained by Brunner and Valen- tin, and by Vierordt, appear especially trust- worthy ; and though the number of experiments is too small to enable us to deduce averages w ith any confidence, yet we may in the meantime consider that, in an adult male of middle age, the average quantity of carbonic acid in the expired air is about 4'3o per cent.* The quan- tity of carbonic acid gas in the expired air is not uniform in the same individual, but varies repeatedly, even in the course of the twenty- four hours, and these variations are deter- mined by certain conditions of the body and of the surrounding media. Period of the day. — Dr. Prout believed that he had discovered that the quantity of car- bonic acid formed during respiration is always greater at one and the same period of the day than at any other ; that this maximum occurs between 10 a. m. and 2 p. m., or generally be- tween 11 A. M. and 1 p. 31.: and that the minimum commences about 8^ 30' p. m., and continues nearly uniform till about 3^ 30' A. M. The beginning and end of the period of minimum evolution of carbonic acid he believed to be connected with the beginning and end of twilight, and he adduces some experiments in favour of this opinion. In these experiments Prout attended only to the percentage of the carbonic acid in the expired air, and took no means to ascertain the volume of air passing through the lungs at the time, — an omission which seriouslv diminishes their value. f Prout's results do not accord with the previous experiments of Brande|, nor ments were 124 in number, and performed upon himself at abnost every hour of the day between 8 A. M. and midnight. The difference between the maximum and minimum percentage is great in Coathupe's experiments ; but this was only found in single cases. § Opus cit. p. 546. These experiments were 34 in number, and performed upon three adult males between 33 and 53 years of age. II Article Respiration in "Wagners Handwbrter- buch, p. 853. Yierordt's experiments were performed upon himself, were nearly 600 in number, were ccai- tinued over a period of nearly 15 months, and were chiefly made between 9 A. m. and 7 r. 3i. Tierordt, in his Physiologie des Athmens, has given in a tabular form the results obtained in 578 experi- ments, p. 21 — 65. f Animal Chemistry, p. 614. 1843. These expe- riments were made on 10 males and 2 females, and between 11 and 12 o'clock A. 3i. * Dalton (Opus cit, p. 25), Dimias (Essai de Statique Chimique des Etres Organises, 3me edit., p. 87. 1844), and Gay Lussac (Annales de Chimie et de Physique, torn. xi. p. 14. 1844), estimate the average carbonic acid in the expired air at 4 per cent. Apjohn (Dublin Hospital Reports, vol. v. 1830), and Macgregor (TransactioiLS of British Sci- entific Association for 1840, p. 87), estimate it at 3-6 and 3*5 per cent. The esrimate of Allen and Pepys (Opus cit.), and Dr. Fyfe (Dissert. Chemico- Physiol. Inaug. de Copia Acidi Carbonici e Pulmo- nibus inter respirandum evoluti. Edinburgh, 1814)^ making the average quantity 8- to 8-5 per cent., is undoubtedly considerably too high ; and they were led into this error by the impediment to the free respiration occasioned by the imperfect apparatus employed. t Thomson's Annals of Philosophy, vols. ii. and iv. X Nicholson's Journal, vol. xi. p. 82. with the subsequent experiments of Coa- thupe* and Vierordt. -f- It would appear, therefore, that the variations in the quantity of carbonic acid in the course of the dav do not occur at uniform periods, independent ot other circumstances, as Prout supposed. It is, however, proved by the experiments of Schariing:}: upon the human species, by Bous- singault § upon the turtle dove, and by Mar- chand j| upon frogs, that the absolute amount of carbonic acid exhaled is very considerably less during the night than during the day. Scharling gives in the following table the relative proportion of the carbon exhaled during the day and night in six individuals upon M hom he experimented : — Xight. Day. 1. Scharling 1 1-237 2. Thomson 1 1-2.30 ~i. A Soldier 1 1-420 4. An adult Female 1 1-240 5. A Bov - 1-266 6. A Gi^l - \ 1-225 The average proportion is 1 during the night to 1"237 during the day, or, in other words, nearly a fourth part more carbonic acid gas is evolved during the day than during the night. T How much of the diminished evolution of carbonic acid during the night is dependent upon the languor and drowsiness incident to that period, and how much upon the absence of the sun's rays and other causes, it is at present impossible to determine. It appears that this diminished evolution of car- bonic acid during the night does not require the occurrence of sleep, though no doubt it is increased by sleep. Digestion. — Seguin and Lavoisier **, in their experiments upon Seguin found that when he was in a stare of repose and fasting he vitiated only 1-210 cubic inches of oxygen gas in an hour, while, during digestion, this was raised to between ISOO and 1900 cubic * Opus cit. t Physiologie des Athmens, Sec, S. 66. % Aniialen der Chemie und Pharmacie, band xlv. s. 214. 1843. Translated in Annales de Chimie et de Physique, torn. viii. p. 478. 1843. § Axmales de Chim. et de Phys., tom. xi. p. 445. 1844, Boussingault calculates from his experiments that, supposing the entire day to be divided into 12 hours of sleep, and 12 hours of waking, the quantity of carbon consumed in respiration by the turtle-dove during the day and night would be as follows : — Carbon consimied in the day (English Troy grains per hour) 3-981 Carbon consumed in the night (ditto) .. 2-500 fj Journal fiir praktische Chemie, von Erdman und Marchand, band xxxui. S. 148. 1844. ^ Annalen der Chemie und Pharmacie, band xlv. S. 236. ** ^Slemoire de rAcade'mie Royale for 1789, p. 574, 575. Jurine (Encyclope'die Me'thodique, Medecine, article Air, tom. L p. 497. 1787) has also maintained that a greater quantity of air is vitiated during digestion. RESPIRATION. inches. Spallanzani* observed that snails, after a redundant repast, exhaled considerably more carbonic acid gas than when fasting. Similar observations have been made upon insects by Sorg-j- and Newport:};, upon the Mammalia by Zimmermann §, and upon the human species by Scharling ||, Valentin^, and Vierordt. The most complete experiments on this point are those of Vierordt, performed on himself, the results of which are contained in the following tables. His dinner lasted from 30 minutes past 12 to 1 o'clock : — q5 ' minute. Volume of an Expiration. Expired in one minute. arbonic red air. Hours. ■♦J 1 m P< 0) Ph a .2 Air. Carbo- nic acid gas. centage of c in the expii CO M In English cubic inches. 12 2 66-5 82-3 11- 55 12- 77 31- 43 32- 26 362-64 412-17 15-77 18-22 4-32 4-37 Difference 15-8 1-22 •as 49-53 2.45 •05 To ascertain that this increase in the quan- tity of carbonic acid evolved from the lungs was really dependent upon digestion, and not upon any other cause, the experiment was repeated at the same period of the day when he had not dined, and had eaten nothing since his breakfast at 7 o'clock, and the following results were obtained : — Hours. Pulse per minute. Respirations per minute. Volume of an Expiration. Expired in one minute. Per centage of carbonic acid in the expired air. Air. Carbo- nic acid gas. In English cubic inches. 12 1 2 63 64 62^5 10 9 9i 33-25 32-16 35-08 332-58 289-44 334-35 16-49 14- 75 15- 75 4- 69 5- 09 4-73 ** * Memoires sur la Respiration, p. 217 — 223. f Disquisitio Physiologica circa Respirationem In- sectorum et Vermium. 1805. X London Phil. Trans, for 1836 and 1837. § The result of Zimmermann's experiments is given on Vierordt's authority in Wagner's Hand- worterbuch, band ii. S. 884. II Opus cit. In Scharling's experiments the total quantity of carbonic acid exhaled from the body during a given time was determined, and they are, therefore, not liable to the en-ors of those experi- ments where the percentage only Avas ascertained. ^ Opus cit. p. 566. Valentin states that an hour after he had taken a meal of bread and butter, the quantity of carbonic acid given off by the lungs was raised from 616-085 to 627-505 English Troy grains per hour, while after a fast of 16 hours it fell to 579-972 grains per hour. ** Physiologie des Athmens, &c. S. 91 und 94. Notwithstanding, therefore, that Prout failed to observe any decided increase in the quantity of carbonic acid gas thrown off by the lungs during digestion, and that Mr. Coa- thupe maintains from his experiments that the carbonic acid in the expired air increases with increased abstinence from food, and that its maximinn quantity is before breakfast and hnmc- diately before dinner * , we must consider the evidence detailed above perfectly conclusive in proving that the quantity of carbonic acid evolved in respiration is considerably in- creased after a full meal. Fasting. — In describing the effects of di- gestion upon the quantity of carbonic acid evolved from the lungs, we were led to refer to the maimer in which the opposite condition of the body, or that of fasting, operates. That fasting diminishes the quantity of carbonic acid in the expired air is not only proved by the facts already mentioned, but also by the experiments of Scharling upon the human species, of Boussingault upon the turtle dove, and of Marchand upon frogs. The tw'O last experimenters found that in very prolonged fasting the quantity of carbonic acid was greatly diminished. Alcohol. — Dr. Prout states that alcohol, and all Hquors containing it which he had tried, have the remarkable property of diminishing the quantity of carbonic acid gas in the expired air much more than any thing else he had made the subject of experiment, and its effects were most remarkable when taken on an empty stomach. Vierordt mentions, in confirmation of Prout's observations on this point, that in four experiments, after having taken from one half to a bottle of wine, the percentage of carbonic acid had fallen, a quarter of an hour after this, from 4"54 to 4*01, and it continued to exercise this effect from one to two hours. f The quantities of atmospheric air and carbonic acid are calculated in the original tables in cubic centi- metres. In reducing these to English cubic inclicv;, one cubic centimetre has been considered tn lie ( (jual to -06102523 of an English cubic inch. * London, Edinburgh, and iJublm^Philoi*. ]Magaz. vol. xiv. p. 409 and 413. The number of meals and the times at which they were taken explain the re- sults obtained by Mr. Coathupe. He lunched at 1 o'clock p. M., and at 2 p. m. the average percentage of carbonic acid gas was raised from 3-92 to 4-17, and thus so far in accordance with the experiments mentioned above. At 5^ p.m. he took a good dinner, with a pint of wine. Kow, as alcohol diminishes the quantity of carbonic acid evolved from the lungs, this might have counteracted the effects of diges- tion for a time. It must also be remembered that Mr. Coathupe ascertained only the pei'centage, not the absolute quantity of carbonic acid evolved ; and Vierordt ascertained by experiment (Physiologie des Athmens, &c. S. 93) that when he drank wine at dinner the percentage of the carbonic acid in the expired air was diminished ; and that, though its ab- solute quantity was increased, this was not nearh' to the same extent as when no "vWne was taken. Were experimenters ahvays to detail minutely the circum- stances under which they performed their experi- ments, it would frequently be found, as in the present case, that results, apparently most discord- ant, are not so in reality. t Wagner's Handw'brterbuch, band ii. S. 884 ; and Physiol, des Athmens, &c. S. 97. 348 RESPIRATION. A strong infusion of tea has, according to Prout, an effect simihir to alcohol. According to Dr. Fyfe, when a person has taken mercury or nitric acid for some time, the quantity of carbonic acid is diminished. Conditions of the mind. — Prout found that anxiety and the depressing passions diminish the percentage of carbonic acid in the expired air ; and Vierordt, on two occasions, observed this effect, for a short time at least, from mental emotions, both of a joyful and of an opposite nature. Scharling remarked that in those persons who felt very anxious on being enclosed in the box used by him in his expe- riments, the evolution of carbonic acid gas from the body was much diminished. Exercise. — Prout states that moderate ex- ercise, as walking, seems always at first to increase the evolution of carbonic acid, but when continued it ceases to produce this effect, and when carried the length of fa- tigue the quantity is diminished : that violent exercise appears to lessen the quantity from the first, or if any increase occurs, this is trifling and transitory ; and that, after violent exercise, the quantity is much lessened. In Prout's mode of experimenting, the percen- tage of carbonic acid having been alone ascer- tained, we have no certain means of judging of the changes in the absolute quantity of carbonic acid evolved, as the increase in the number of respirations and in the bulk of the air respired, occasioned by exercise, was not taken into account. In the experiments of Seguin and Lavoisier already referred to, it was found that Seguin, when fasting and at rest, vitiated in the hour 1210 cubic inches of oxygen gas : by an amount of exercise equal to raising 15 lbs. to a height of 613 feet, this was increased to 3200 while still fasting, and to 4600 cubic inches, while digesting food. In Scharling's experiments, where the absolute quantity of carbonic acid gas evolved from the whole body in a given time was ascertained, the quantity of carbonic acid was increased during exercise. Vierordt ascertained that during the increased respiratory movements occasioned by moderate exercise, that on an average there w-as an increase per minute of 18*978 English cubic inches in the expired air, containing an increase of 1*197 cubic inch of carbonic acid gas, giving, however, an in- crease of carbonic acid gas in the expired air of only 0*140 per cent. There can, therefore, be no doubt that the evolution of carbonic acid gas from the lungs can be considerably increased by exercise.* Temperature. — The effects of low tempera- tures upon the respiratory process, as ascer- tained by Spallanzani and Treviranus upon snails and insects, by Marchand upon frogs, and by different observers upon the hyber- nating warm-blooded animals, are not appli- * G. R. Treviranus (Zeitschrift fiir Physiologic, vierter baud, S. 29. 1831) and Newport (opei-a cit.) in their experiments upon insects, observed a mark- ed increase in the exhalation of carbonic acid gas in these animals during active voluntar}^ move- ments. cable to the human species, since the re- duction of the temperature to a certain extent induces in these animals a lethargic condition, well known under the term hy- bernation, altogether different from its effects upon man and the other warm-blooded animals. Seguin and Lavoisier state that in their ex- periments, Seguin, in a temperature of 82° Fahr., fasting and at rest, consumed, in the space of an hour, 1210 French cubic inches of oxygen ; while in a temperature of 57° Fahr., he consumed in the same time 1344 cubic inches.* Crawford f, in experiments upon guinea-pigs, ascertained that these animals, in a given time, deteriorate a greater quantity of air in a cold than in a warm medium. The most perfect experiments on this point, at least on the human species, are those of Vierordt.J He ascertained, by numerous trials upon himself, the effects of temperature from 37°*4 to 75°*2 Fahr. From a t.ible, showing the results obtained, both upon the respiration and the pulse, at each degree of the centigrade thermometer within the limits mentioned, he has constructed the following shorter table, where the first table is arranged in two divisions, — the one containing the aver- age of all the lower, and the other the average of all the higher temperatures. In the follow- ing table the measures of the expired air and carbonic acid have been reduced to English cubic inches. Pulse > . ^ f Respirations jP^^°^^°"*^ { Volume of an expiration") in cubic inches J Expired air^ C car- Vper minute < bonic acid J Carbonic acid gas in the"i 100 parts of the expired V air - - - J Bai-ometer, in English ) inches - - - f S3 ^ > S 72*93 12-16 33*44 406-99 18*25 4*48 4*28 29-719 29*647 71-29 11*57 31*76 366-97 15-72 5 fcb 1-64 0-59 1*68 40*02 2*53 0-20 The experiments of Letellier^ on warm- blooded animals agree in their results with * Memoires de I'Acade'mie R ovale for 1789. f Experiments and Observations on Animal Heat, p. 311—315. 2nd edit. 1788. X Wagner's Handworterbuch, band ii. S. 878, 879, und 880. Physiologic des Athmens, S. 73—82. § Comptes Rendus, torn. xx. p. 795. 1845. An- nales de Chimie et de Phys. tom. xiii. p. 478. 1845. Letellier has thro"\vn the results of his experiments into the folloAAing table. He does not state whether he measured the temperature bj Reaumur, or the RESPIRATION. 3¥J those of Vierordt. He found that the quan- tity of carbonic acid gas evolved from the body at the freezing point, was double of that at an elevated temperature, in the two mice and guinea-pig, and a little more in the canary and pigeon. There can, therefore, be no doubt that more carbonic acid gas is evolved from the body in a cold, than in a warm tem- perature. Effect of the seasons. — Dr. W. F. Edwards* ascertained, by several well-devised experi- ments, that birds placed under exactly the same circumstances, and with the surrounding air of the same temperature, consumed more oxygen in winter than in summer, and this appears to be connected with that change in the constitution of the warm-blooded animals in the colder regions of the earth, by which they are enabled to generate more caloric in winter than in summer. Barometric pressure. — Legallois found that when warm-blooded animals breathed air in a vessel under an atmospheric pressure reduced to 30 centimetres (] 1*811 English inches), the quantity of oxygen gas consumed was dimi- nished.f Prout, on the other hand, informs us, that, in every instance in his experiments, any remarkable increase in the percentage of carbonic acid in the expired air was accom- panied by a sinking barometer. J Vierordt tested the effects of a range of the barometric scale between 330''^ (29-309 English inches) and 340''' (30-197 English inches), and has thrown the results into a tabular form. The measure of the expired air was calculated under the ordinary pressure of 336"^ (29-84'l English inches). He found that a rise of 5''^*67, (the mean between the experiments at the lower and those at the higher pressures,) produced the following effects : — It increased the pulsations in one minute 1 '3 „ respirations O'T-i „ expired air (cubic in.) 35*746 As, however, the percentage of the carbonic acid in the expired air was greater at the lower than at the higher pressures, in the Centigrade scale, but we believe that it was the latter. For a Canary For a Pigeon For two Mice For a Guinea Pig Surrounding Temperature. From 150to 20° From 30Oto40° At the freezing point. grammes 0-250 0-684 0-498 2-080 grammes 0-129 0-366 0-268 1*453 grammes 0*325 0-974 0*531 3-006 * De rinfluence des Agens Physiques sur la Vie, chapitre vi. t Annales de Chimie et de Physique, tom. iv. p. 113. 1817. X Thomson's Annals of Philosophy, vol. iv. p. 335. proportion of 4*450 to 4*141, the difference between the absolute quantity of that gas in the expired air at tlie higher exceeds so little that at the lower pressures, that it may be reckoned as nil.* Age, sex, and constitution of body. — The quantity of carbonic acid evolved from the body is not only influenced by the ingesta and the varying conditions of the surrounding media, but also by the age, sex, and constitu- tion of the body. The only important re- searches into the effects which these last con- ditions of the body have upon the evolution of the carbonic acid, are those of Andral and Gavarretf, and Scharling J ; and though they are far from having exhausted the subject, they possess the merit of having been care- fully and accurately conducted, and of being carried on in the right direction. Andral and Gavarret availed themselves in their ex[)eri- ments of the apparatus suggested by Dumas and Boussingault. Part of this apj)aratus consists of a mask, which can be fitted air- tight to the face, and having a tube on each side, on a level with the commissures of the lips, provided with valves permitting the ex- ternal air to pass in, but preventing its pas- sage outwards. In front of the mouth there is a large aperture for conducting outwards the expired air ; and to this a tube can be at- tached for conducting it into the receivers and other parts of the apparatus prepared for ascertaining the quantity of carbonic acid gas. A person can breathe through this apparatus without constraint ; and the experiments were all performed between one and two o'clock P.M., each lasting from eight to thirteen mi- nutes, and the individuals experimented upon were placed, as far as possible, under the same conditions with regard to food, muscular exertion, and state of the mind. They ex- perimented upon sixty-two individuals of dif- ferent ages, and of both sexes. They restricted their valuation of the quantity of carbonic * Dr. Hutchinson ( Medico- Chirurgical Transac- tions of London, vol. xxix. p. 228) has given some expeiiments upon the effects of an increased barometric pressure upon the frequency of the re- spiratory movements. These were made upon six persons before and after descending a nunc, 1488 feet deep, where the barometric pressure was 1-54 inch more than at the level of the sea. As there was a difference of 10 degrees in the temperature at the top and bottom of the mine, this, ought to be taken into account in judging of the results. The pulse was increased at the bottom of the mine on an aver- age 1-3 per minute, and the respirations 2*4 per mi- nute. The accounts given by travellers of the effects upon their respiration in elevated regions are so discordant that we can deduce no very satisfactory conclusions from them. t Annales de Chim. et de Phys. tom. ^^ii. p. 129. 1843. X Annalen der Chemie vmd Phannacie, band xlv. S. 214. 1843, translated in Annales de Chim. et de Phys. tom. viii. p. 478. 1843. In Scharling's ex- periments, as in those of Andral and Gavarret, the absolute quantity and not the percentage of car- bonic acid gas in the expired air was determined. In Scharling's first experiments, the carbonic acid gas given off at the external surface of the body was mixed with that given off by the lungs. 350 RESPIRATION. acid evolved from the lungs to one hour, being perfectly aware of the fallacy of at- tempting to estimate from experiments so limited as to time, the quantity given off in the twenty-four hours. Scharhng conducted his experiments in a different manner. He en- closed the individuals experimented on in a box, perfectly air-tight, and so large as to permit a person to work, read, or even sleep, during the experiment. Tubes were fixed in the box, to admit the external air freely, and to conduct the expired air into an apparatus fitted for determining the amount of the car- bonic acid. The individuals experimented on remained in the box generally for an hour at a time, sometimes an hour and a half, but also often from thirty to forty minutes only ; and precautions were taken to keep up a free circulation of atmospheric air through the box during the whole of the experiment. His experiments were performed upon six persons, of different ages and of both sexes. Andral and Gavarret have drawn the fol- lowing conclusions from their experiments: 1. The quantity of carbonic acid gas ex- haled from the lungs, in a given time, varies according to the age, the sex, and the consti- tution of individuals ; and that, independently of the weight of the body. 2. At all periods of life extending from 8 years (the earliest age subjected to experiments) up to the most advanced old age, the quantity of carbonic acid evolved from the lungs differs in the two sexes, but, cceteris paribus, the male exhales a considerably larger quantity than the female. This difference is most marked between 16 and 40 years of age, during which period the male generally evolves nearly twice as much as the female. 3. In the male, the quantity of carbonic acid exhaled goes on conti- nually increasing from 8 to 30 years of age, and becomes suddenly very great at the age of puberty. After 30 years of age it begins to decrease, and this so much the more de- cidedly as the person approaches extreme old age, at which period it may be reduced to the quantity evolved at 10 years of age. 4. In the female also, the evolution of carbonic acid increases from infancy up to puberty ; but at this period, contrary to what takes place in the male, it remains stationary, so long as the menstrual secretion continues natural. At the time the menses cease, the evolution of carbonic acid gas from the lungs undergoes a marked augmentation ; but after a while it begins to decrease, as in the male, and pro- portionally as she advances towards old age. 5. In the female, during gestation, the exhala- tion of carbonic acid from the lungs equals the quantity exhaled at the period of the ces- sation of the menses. 6. In both sexes, and at all ages, the quantity of carbonic acid is so much the greater, as the constitution is stronger and the muscular force more deve- loped. The most important of the data upon which the above inferences are founded are as follows : — In the male child, in his progress upwards from his 8th to his 15th years, the quantity of carbon given off by the lungs was raised, on an average, from 5 grammes (77-165 Troy grains) to 8*7 grammes (134-267 Troy grains) per hour ; while in the female at the same age it was on an average 1 gramme (15-433 Troy grains) less per hour. In the male at 16 years of age, or soon after puberty, it sud- denly increased to 157"416 Troy grains, on an average, per hour ; and from this period up to the age of 20 and 25 it gradually increased, on an average, to 172*849 and 191-369 Troy grains per hour. At this {)oint it remained nearly stationary until about 40 years of age, when it began to undergo a slight diminution, but not to any great extent until 60 years of age. Adult females, who menstruated regu- larly, lost, on an average, 98*771 grains only of carbon, by the lungs, in an hour, — a quan- tity not greater than that lost by girls. Take the average loss of carbon, by the lungs, in the male at 174*392 grains between the ages of 15 and 20 years, it is, on an average, 155*873 grains between 40 and 60 years; and 141*953 grains between 60 and 80 years. In the fe- male, at the period of the cessation of the menses, the loss of carbon is suddenly ele- vated from an average of 98-771 to 129*637 grains per hour; and a similar elevation, and nearly to the same extent, was observed in four females during pregnancy. In females between 50 and 60 years of age, the loss was 11 2*660 grains, and between 60 and 80 it was, on an average, 104*944 grains in an hour. In one female of 82 years, it was 92*595 grains, and in a male of 102, but remarkably hale for his years, it was 91*590 grains. In a male, aged 26, and remarkable for his muscular de- velopment, the loss was as high as 217*105 grains, while in another male, aged 45, of mo- derate height, but extremely feeble muscular development, it amounted on an average only to 132*723 grains an hour.* Scharling, after allowing seven hours for sleep to an adult, and nine for a child, calculates, from his experiments on six individuals, the amount of the loss of carbon from the body as follows : — Male - Average of men Boy Girl - Aver, of cliildi-en "Woman 73 r 9 fcJD < 1 Quantity of carbon Weight exhaled in grains. OI uouy 111 Troy lbs. In 24 hours. In 1 hour. 16 28 35 154-73 219-70 175-49 3453-90 3699-50 3386-77 143-91 154-14 141-11 26i 183-30 3513-39 146-39 9| 10 58-96 61-64 2054-53 1929-89 85-60 80-41 60-30 1992-21 83-10 19 149-41 2540-88 105-87 1 * Brunner and Valentin (opus cit. p. 567), from RESPIRATION. 351 In these experiments of Scharling the evo- lution of carbonic acid by the skin was in- cluded, with that evolved through the mouth and nostrils ; and the quantity is calculated for the twenty-four hours. But in some sub- sequent experiments, by uniting the use of the mask used by Andral and Gavarret with the box, he has been enabled to ascertain the relative amount of the loss by these two dif- ferent channels in an hour. In other respects, he has endeavoured to assimilate his experi- ments, in regard to the hour of the day, &c., to those of Andral and Gavarret, and has given the following comparative view of the results : — 1. Male aged 28 years 2. — — 16 — 3. Boy — 9| — 4. Young Woman 19 — 5. Girl - - 10 — Total quantity of carl)on from the Avhole body in Troy grains. Carbon from general sur- face of body. Carbon expired through the mouth and nostrils in Troy grains. >Scharling. Andral and Gavarret. 181-183 169-763 101-086 128-340 95-622 5-756 2-793 1-913 4-197 1-913 175-426 166-969 99-172 124-143 93-709 191-369 157-416 91- 054* 108-031 92- 598 1 Injluence of the respiratory movements upon the evolution of carbonic acid from the lungs. — This point has been particularly ex- amined by Vierordt in 171 experiments upon himself, and he has ascertained that the fre- quency, extent, and duration of the respiratory movements have a marked effect, not only upon the relative proportion of the carbonic acid gas in the expired air, but also upon the absokite quantity evolved from the lungs in a given time.:]: We shall afterwards find, when we come to describe the theory of respiration, that the results obtained by Vierordt are of considerable importance in a theoretical point of Frequency of the respiratory movements. — When the number of respirations is less than usual, the percentage of the carbonic acid in the expired air is increased, while its absolute quantity is diminished ; on the other hand, when the respirations are more frequent than usual, the percentage of carbonic acid in the expired air is diminished, while its absolute quantity is increased. Vierordt endeavours to point out that the diminution in the per- centage of the carbonic acid gas in the ex- six experiments on themselves, calculate that 172-664 Troy grains of carbon were thrown off from the lungs in an hour. t This table is given in the form into which it has been thrown by Hannover (De Quantitate relativa et absoluta Acidi Carbonici ab homine sano et jegroto exhalati, p. 17. 1845) and the kilo- grammes and grammes in the original table have been reduced to Troy pounds and Troy grains. * As the boy upon whom Scharling experimented was of slender form, he has taken the average of the results of Andral and Gavarret upon two boys of 10 and 8 years as the standard of comparison in tliis case. t Wohler and Liebig's Annalen der Chemie und Pharmacie, band Ivii. S. 1. 1846. The male adult and the boy were naked during the experiment. X Physiologic des Athmens, vierter abschnitt, S. 102—149. pired air when the respirations are more fre- quent, probably bears a certain proportion to their frequency or length per minute, sup- posing their bulk to be the same. The operation of this law, according to Vierordt, may be illustrated as follows. Let us take the average number of respirations in a state of rest as 12, and suppose these to be doubled or increased to 24, the relative percentage of carbonic acid will be dimi- nished by 0*8 ; if the number of respirations be again doubled, or increased to 48, the carbonic acid will suffer a still further dimi- nution of 0*4 per cent. ; and if the respira- tion be again doubled, and increased to 96 per minute, the carbonic acid will suffer a farther reduction of 0 2 per cent. On the other hand, if the number of respirations be less than 12 (here taken as the normal number of respirations by Vierordt) by one half or reduced to 6 in the minute, the re- lative percentage of carbonic acid will be in- creased above what it is in the normal fre- quency by 1*6. If the percentage of carbonic acid in the expired air be 4*1, when the re- spirations are 12 in the minute, it will be 5"7 per cent, when the respirations are 6, and 2'7 per cent, when they are 96 in the minute. Proceeding upon the existence of this law, he supposes that if the respirations were increased from 96 to twice that number, or 192, the percentage of the expired air would suffer a farther reduction of only O'l per cent. ; in other words, it would be reduced from 2'7 to 2*6 per cent. This last ratio, viz. 2 6, he believes to be the smallest percentage of carbonic acid gas that the expired air can present. If Vierordt be correct in supposing that the percentage of carbonic acid in the expired air has a fixed arithmetical proportion to the frequency or length of the respiratory movements, we could, after determining the normal number of respirations, the bulk of air expired, and the percentage of carbonic acid 352 RESPIRATION. gas, when the body is in a state of rest, be able to determine both the relative and the absolute quantity of carbonic acid gas in the expired air from the number of respirations alone, when these are either increased above, or diminished below the normal number, provided the bulk of each respiration continues equal. He has constructed the following table to illustrate the variations in the absolute quan- tity of carbonic acid gas occasioned by altera- tions in the frequency of the respiratory move- ments. The normal number of respirations is supposed to be 12, the average bulk of each respiration to be oOO cubic centimetres (30"o Enghsh cubic inches), and the percentage of carbonic acid to be 4'1. I Tolume Yolvune of carbo- oftheex- nic acid Number Percentage of respi- of carbonic rations in acid in the a minute, expired air. pired air gas in the in a minute. I air in a Volume of carbo- nic acid minute. piration. Measured in English cubic inches at a temperature of 98°-^ F., and under a baro- metric pressure of 29*811 j English inches. | 6 5-7 183-000 10-431 1-738 12 4-1 366-000 15-006 1-250 24 3-3 732-000 24-156 1-006 48 2-9 1464000 42-456 0-884 96 2-7 2928-000 79-056 0-823 Bulk of the air expired. — The quantity of air thrown out of the lungs at each expiration has also an influence upon the percentage and absolute quantity of carbonic acid gas in the expired air. Vierordt, in six experiments, found that while the average of carbonic acid gas in the expired air in a normal expiration in a state of rest was 4-78 per cent., in the deepest expiration he could make, it was 4*05 per cent. The stoppage of the respiratory movements for a time has also a marked effect upon the quantity of carbonic acid in the expired air. Vierordt has made four series of experiments upon himself to ascertain the extent of this influence upon the quantity of carbonic acid evolved from the lungs. In the first series he shut his mouth and held his nose from 20 to 60 seconds (the longest period he could con- tinue the experiment), and then made the deepest possible expiration. In the second series he made the deepest inspiration pos- sible, then suspended the respiratory move- ment for a longer or shorter time, at the ter- mination of which he made the deepest ex- piration. This experiment he was able to prolong to 70, 90, and even 100 seconds. In the third series he made an ordinary inspira- tion before suspending the respiratory move- ments, and after this suspension had con- tinued for different periods up to 30 seconds, he made an ordinary expiration. The fourth series of experiments was to ascertain the period of time after the stoppage of the respi- ratory movements when the percentage of carbonic acid gas becomes uniform in the different parts of the lungs and air passages, and this he found took place after 40 seconds. He has arranged the results of the three first series of experiments in several tables, ex- hibiting the difference between the percentage and absolute quantity of carbonic acid gas in the expired air at various periods, after the suspension of the respiratory movements under the circumstances mentioned, and when the respiratory movements proceed in the normal manner. In the first series of ex- periments, the percentage of the carbonic acid in the expired air, after the respiratory movements had been suspended 20 seconds, was higher by TTS than when these move- ments were normal, but the absolute quantity evolved from the lungs had diminished by 2*642 English cubic inches, and at the end of 55 seconds its percentage had increased 2-32, but its absolute quantity had diminished to the extent of 12 3S2 cubic inches. In the second series of experiments, where the deep- est possible inspiration preceded, and the deepest possible expiration followed, the sus- pension of the respiratory movements, the absolute quantity of carbonic acid gas evolved from the lungs, for the first 15 seconds, was somewhat more than what would have oc- curred had these movements proceeded in the normal manner, but after this it began to diminish ; and when the respiratory move- ments had been suspended for 95 seconds, it was diminished to the extent of 14-078 English cubic inches, though its percen- tage had considerably increased. At the end of the l(tO seconds, the percentage of the expired air was 3*08 above the normal quan- tity in ordinary respiration. In the third series of experiments, the carbonic acid in the expired air, at the end of 30 seconds, was 1*55 ptr cent, above the normal quantity. These experiments prove, therefore, that when the respiratory movements have been suspended for a time, the percentage of carbonic acid in the expired air will increase, but the absolute quantity evolved from the lungs will be diminished, so that the increase in the per- centage of this gas does not by any means compensate for the diminished quantity of air passing through the lungs. When the same air is breathed more than once, the quantity of carbonic acid in it is increased. Allen and Pepys * state that air, passed 9 or 10 times through the lungs, con- tained 9 5 per cent, of carbonic acid gas ; and the greatest quantity obtained, in air breathed as often as possible, was 10 per cent. Mr. Coathupe f found the average quantity of carbonic acid gas, in air in which warm- blooded animals had been confined until they were becoming comatose, to be 10*42 per * Fhilos. Transact, of Loudon for 1808. t Opus cit. RESPIRATION. 353 cent. ; while, if they were allowed to remain in it until they had become asphyxiated, it con- tained ]275 per cent. Vierordt, in three experiments, breathed, from 1^ to 3 minutes, a volume of air amountin;^ to 427 English cubic inches, and found, on an average, the carbonic acid gas l*o per cent, above that contained in air breathed only once. The percentage of carbonic acid in the expired air differs at different periods of the same expiration. As the air ex[)elled in the first part of an expiration consists chiefly of that contained in the trachea and upper part of the air passages, its amount of carbonic acid gas must necessarily be smaller than that expelled at a later period of the expiration. Allen and Pepys found the carbonic acid gas in the first and last portions of air in a deep expiration to differ as widely as 3 5 and 9*5 per cent. Dalton states that while the ave- rage carbonic acid in an ordinary expiration is 4 per cent., the last portion of a forced ex- piration contains 6 per cent. Vierordt divided the air of an ordinary expiration as far as possible into two equal parts, and in twenty- one experiments ascertained that while the average quantity of carbonic acid in the whole expiration was 4*48, the first half contained 3*72 per cent., and the last half 5*44 per cent. We have already seen, that Vierordt concludes from his experiments that the air, after a sojourn of about 40 seconds in the respiratory apparatus, has the same percentage of car- bonic acid gas in the different parts of the lungs and air passages. From the above details, it must be obvious that nearly all the attempts made to estimate exactly the average quantity of carbon evolved in the form of carbonic acid gas from the body in the 24 hours are entitled to very little con- fidence. The greater number of these are founded on a few experiments performed upon one or a very small number only of indi- viduals in a state of rest, and upon the result of a few respirations in some cases performed under constraint. The estimate of the amount of loss of carbon in the 24 hours from the lungs and external surface of the botly, based upon the direct method of experiment, in which the greatest number of the circumstances that influence the evolution of carbonic acid gas from the lungs were taken into account, is undoubtedly that of Scharling, though this even must be regarded as an approximation only to the truth. Suppose we take the average estimate of the two adult males be- tween 28 and 35 years of age for the 24 hours, as given by Schai ling *, the loss of carbon by the lungs and skin is 3543-13 Troy grains, or 7-382 oz. Troy, f Liebig % has endeavoured * Vide table given in p. 350. t The estimates of the average loss of carbon, in the form of carbonic acid gas, from the kings in the twenty-four hom-s by other experimenters, differ con- siderably. Lavoisier and Seguin estimated the loss of carbonic acid gas at 14,930 cubic inches, Avhich they believed would yield 277G-304 grains Trov; Messrs. Allen and Pepys at 39,534 cubic inches 'of carbonic acid gas, containing rather more than 11 oz. Troy of carbon ; and Mr. Coathupe at 10,666 cubic VOL. IV. to ascertain the quantity of carbon lost at the lungs and skin in the 24 hours by the indirect method of research, which he maintains to be by far the most trust-worthy. He [jroceeded to ascertain the quantity of charcoal in the daily food and drink of a body of soldiers, and after deducting the comparatively small quan- tity of this substance that passes off" in the faeces and urine, the remainder was taken as the amount of carbon that unites with oxygen, and escapes in the form of carbonic acid tras by the lungs and skin. From the data thus obtained he calculates that an adult male, taising moderate exercise, loses 13-9 oz. of carbon daily by the lungs and skin ; and tliat 37 oz. of oxygen gas must be daily absorbed from the atmospheric air for the purpose of converting this charcoal into carbonic acid gas. From similar exi)eriments upon the in- mates of the Bridewell at Marienschloss (a prison where labour is enforced), he calculates that each individual lost in this manner iO'5 oz. of carbon daily ; while in another prison, where the inmates were deprived of exercise, this loss amounted only to 8-5 oz. daily. * Allowing that this indirect method of research is more accurate than the direct, — a point which we are not at present prepared to de- termine, — the accuracy of the data upon which Liebig's inferences rest regarding the quantity of carbonic acid exhaled from the lungs and skin in an adult using moderate exercise, has been called in question by Schar- ling. f He endeavours to prove, by an ana- lysis of the food and drink allowed to the sailors on board of his Danish Majesty's vessels of war, that the whole carbon' taken daily into the body of each of these individuals must be somewhat less than 10| oz.; yet these sailors are subjected to harder work than ordinary seamen. J The quantity of carbonic acid gas evolved from the body in respiration varies greatly in the different divisions of the animal kingdom. It is greater in birds, in proportion to their bulk, than in the cold-blooded vertebrata, and still smaller in the invei tebrata, with the ex- ception of insects. § The ascertainment not feet of carbonic acid gas, yielding 2386-27 grains, or 5-45 oz. avoirdupois. Vierordt, from numerous ex- periments on himself, ascertained that when in a state of rest the quantity of carbonic acid gas ex- haled from the lungs per minute was for the maxi- mum 452 cubic centimetres (27-572 Eng. cub. in.\ for the minimum 177 cub. cent. (10-797 Eng. cub. in.), and for the average 261 cub. cent. (12-261 Eng. cub. in.), so that the relation of the minimum and maxi- mum Avas 100 : 255. If the quantity of carbonic acid evolved from the lungs differs so much at dif- ferent times in the same individual in the minute, and is so materially influenced by the varying con- ditions of the body, how difficult must it be to ascertain the average quantity during the twenty- four hours. X Animal Chemistrv, &c., edited by Dr. Gregoi-y, p. 13 ; 3rd edit. 1846."^ * Opus cit. p. 46. I Annalen der Chemie und Pharmacie, von "\Voh- ler und Liebig, Band Ivii. S. 1. 1846. Opus cit. p. 9. The results of the various experiments upon A A 354 RESPIRATION. only of the absolute quantity of carbon which escapes from the body in the form of carbonic acid gas in the different classes of animals, but also the relative proportion of tliis to the weight of the body, is a matter of considerable physiological interest, especially with refer- ence to the source of animal caloric. From the experiments of Scharling, Andral, and Gavarret, it is evident that the young of the human species relative to their weight consume considerably more oxygen gas, and evolve more carbonic acid gas by respiration, than the middle-aged ; and that the latter again evolve more carbonic acid than those far advancetl into old age. Valentin and Brunner have calculated, from experiments performed on Valentin, who at the time was 33 years of age, that for every gramme weight (15"433 Troy grains) of his body, there w^as evolved "0089 Troy grain of carbonic acid gas, containing *0024 Troy grain of carbon ; and this calcu- lation approximates pretty closely to one based upon the results of Andral and Gavarret upon the evokition of carbon, combined with those of Quetelet upon the average weight of the body at this period of Hfe. * The follow- ing table, calculated from the experiments of different observers, to show the quantity of carbon consumed in the 24 hours for every 100 grammes weight (1543'3 Troy grains) of the body in the four divisions of the verte- brata, is given by Vierordt : — Troy Grains. Tench (Provencal and Humboldt) -370 = 1 Frog ( March and) 1 '342 = 4 Man (Scharling) 4-506= 12 Pigeon (Boussingault) 42-317 = 114 Quantity of oxygen absorbed at the lungs. — That a quantity of oxygen gas greater than what is necessary to form the carbonic acid gas in the expired air disappears from the inspired air, is now placed beyond a doubt. The quantity of oxygen gas that disappears from the inspired air by absorption at the lungs is not uniform, even in the same indi- vidual, for any length of time, and the varia- tions in this respect are in all probability determined by the same circumstances which affect the evolution of carbonic acid gas, the absorption of oxygen being increased when the evolution of carbonic acid is increased, and vice versa. Dalton calculated that he himself respired 500 cubic feet of atmospheric air, containing 105 cubic feet of oxygen, in the 24 hours, and that 25 cubic feet of the oxygen, weighing 15,120 grains, or 2*6 lbs. Troy, were absorbed at the lungs. Valentin and Brunner, in 34 analyses of the air expired the quantity of carbonic acid evolved in respiration in different classes of animals up to the period when the work Avas published, are thrown into a tabular foi-m in Burdach's Physiologic, 2nd edition, trans- lated by Joiu-dan, toui"^ ix. p. 512. * A table constructed on these data, exhibiting the probable quantity of carbon which combines "nith oxygen to fonn the carbonic acid gas evolved at the liuigs at different ages in the hmuan species, is given-at p. 569 of Valentin's Lehrbuch. by 3 individuals between 33 and 54 years of age, found the average quantity of oxygen gas to be 16 033, the maximum 17-246, and the minimum 14-968 parts by volume in the 100 parts of the expired air. Proceeding on these results of Valentin and Brunner, we may esti- mate the average amount of oxygen that dis- appears from the inspired air at 4-78 by vohmie in the 100 parts. While the experiments upon the relation of the quantity of oxygen absorbed at the lungs to that of the carbonic acid gas evolved, made by Lavoisier, Sir H. Davy, and Dalton on the human species, by Legallois, Dulong, Despretz, and Dr. W. F. Edwards upon the warm-blooded animals, by Treviranus upon several cold- blooded animals, and by Marchand upon frogs, all concur in making the oxygen absorbed greater than what is necessary to form the carbonic acid exhaled, they exhibit very con- siderable differences in the relative propor- tions of the absorbed oxygen and exhaled carbonic acid gas. In some of these experi- ments, the ox} gen absorbed was considerably greater than what is necessary to form the carbonic acid gas. In Marchand's experiments on frogs subjected to prolonged fasting, the relation of the oxygen absorbed to the car- bonic acid evolved constantly increased, until it amounted to between 410—430 : 100.* Valentin and Brunner, in their experiments on the human species, found the relative proportions of these two gases to approximate so closely to their diffusive volumes, that they believed the small difference between the results obtained by actual experiment and when calculated according to the law of the diffusion of gas, discovered by Graham, arose from incidental circumstances ; and as the diffusive volume of carbonic acid gas is to oxygen gas as 1 : 1*1742, they maintain that for every 1 volume of carbonic acid gas evolved from the blood, 1-1742 volume of oxygen gas is absorbed. Valentin has given the following table, constructed from facts furnished by Quetelet, Andral, and Gavarret, conjoined with calculations of the relative quantities of oxygen absorbed and carbonic acid evolved according to the law of the diffusion of gases, to exhibit the weight of the body, the quantity of carbon consumed in respiration, and the probable amount of oxy- gen absorbed and carbon consumed at the different periods of hfe in the human spe- cies f : — * At page 563 of Valentin's Lehrbuch are two tables exhibiting the relative proportions of oxygen gas absorbed and carbonic acid evolved, as ascer- tained by direct experiment, and as calculated ac- corthng to the law of the diffusion of gases. We shall have occasion to make some remarks on this subject when we come to discuss the theorj- of respi- ration. t Opus cit. p. 571. The weights and measures in the original table are here reduced to Troy Aveight and English cubic inches. RESPIRATION. 355 Years of Average weight of body in Troy pounds. 15 16 18—20 20—24 40—60 60—80 59-62 124-34 143-05 m (174-15 J (184 36 J m (175-49 j Fin (164-02 j Carbon consumed, in Troy grains. Inl hour. 77-165 134-267 166-676 175-936 188-282 155-873 141-983 In 24 hours. 1864-306 32-22-410 4000-283 4222-468 4518-782 3740-959 3407-606 Quantity of oxygen which disappears from the inspired air. In grains. In Ihour. 240-955 419-252 520-447 549-399 587-904 486-710 443-34 In 24 hours, 5782-806 10062-069 12490-852 13184-782 14110-083 11081-052 10640-250 Overphis of oxygen above what is neces- Volume of oxygen that disappears from the inspired air un sary to form the car- der a pressure of 29-92 bonic acid gas. In Troy grains. In Ihour. In 24 hours. 35-233 61-207 75-976 80-359 85-622 71-099 64-926 845-604 1468-974 1823-439 1928-631 2054-934 1706-395 1558-239 inches, and a tempe rature of 32° F. In English cubic inches. In Ihour. In 24 hours. I I 526-907 12045-770 1154-142 27699-422 1432-669 , 34384-076 1512-432 36298-371 1618-436 38842-098 1339-847 32156-346 1220-478 ^ 29291-495t From the details given above we may ob- tain information of considerable importancn on several practical points. A consideratioe of the large quantity of atmospheric air pass- ing through the lungs in the 24 hours, and the extent to which it is vitiated by this in the removal of a part of its oxygen and the sub- stitution of a quantity of carbonic acid gas, will assist us in acquiring definite information regarding the amount of ventilation required in the apartments of our private and public buildings. It appears that between 400 and 500 cubic feet of atmospheric air pass daily through the lungs of an adult enjoying mode- rate exercise ; and the estimate of Dalton, that 23 cubic feet of oxygen gas are, during the same period, aborbed at the lungs, is pro- bably not far from the average. The same air cannot be breathed twice without in- ducing prejudicial effects, so that at each in- spiration entirely fresh air ought to be sup- plied, or the air ah'eady breathed ought to be so largely diluted by the admission of fresh air as to be restored very nearly to its original composition. Leblanc informs us, that in the Chamber of Deputies in Paris, where the system of ventilation is based upon the prin- ciple of furnishing to each individual from 10 to 20 metres cubes (353-316 to 706-331 English cubic feet) of air per hour, the air issuing from the apartment contained from 2 to 4 of carbonic acid gas in the 1000 parts by weight.* The quantity of pure atmospheric air here furnished is probably somewhat insuf- ficient, if the presence of 1 part of carbonic acid in the 100 of atmospheric air be likely to act prejudicially when breathed for a long time * Annales de Chimie et de Physique, troisieme se'rie, tom. v. p. 241. 1842. In the Model Prison at Pentonville from 30 to 45 cubic feet per minute, or from 1800 to 2700 cubic feet per hour, of pure fresh air is made to pass into every cell. (Report of the Surveyor-General on the Construction, &c. of Pen- tonville Prison. 1844.) continuously. From Dr. Snow's experiments, it appears that the prejudicial effects of breath- ing air deteriorated by respiration, is not en- tirely due to the presence of an increased quantity of carbonic acid gas, but also in a considerable degree to the diminution of the oxygen. He found that birds and mammalia introduced into an atmosphere containing only from 16 to lOi per cent, of oxygen soon died, though means were adopted for remov- ing the carbonic acid formed by respiration.* The increase of the carbonic acid gas to 12 and 20 per cent., provided the oxygen gas was still as high as 21 per cent., did not appear to enfeeble the vital actions more rapidly than the diminution of the oxygen to the extent above stated. Any notable diminution in the percentage of the oxygen gas, even when no carbonic acid is present, cannot take place without danger to the warm-blooded ani- mals-{-, and the carbonic acid in the air respired acts more or less energetically in destroying life, as it has been produced at the expense of the oxygen of the air, or been added to it already formed .J * Edinburgh Medical and Surgical Journal, vol. Ixv. 1846. A green-linnet was confined in a vessel containing 2000 cubic inches of air, consisting of 16 of oxygen and 84 of nitrogen in the 100 parts by volume, and it died in ten minutes. A mouse was introduced into the same vessel filled with air con- taining 10 J per cent, of oxygen, and in five minutes it was no longer able to stand. f There is a marked difference in this respect be- tAveen the cold-blooded and warm-blooded animals. Vauquelin (Annales de Chimie, tom. xii. p. 271. 1792) in his experiments upon some snails, found that when confined in a quantity of air, all the oxygen had disappeared at the time of their death ; and Spallanzani observed the same thing in a few of his experiments on the same animals. Matteucci (Le- mons sur les Phenomenes Physiques des Corps Yi- vants, p. 115. 1847), obtained similar results on a torpedo confined in a limited quantity of water. X Dr. Snow infers from his experiments on the lower animals that in the human species " five or A A 2 S56 RESPIRATION. The experiments on the effects of dimi- nished frequency of the respirations in re- ducing the amount of carbonic acid gas evolved from the blood in a given time, are in accordance with observations made on the state of the blood and its circulation, when this condition has been induced in man or in the other warm-blooded animals. A diminu- tion in the frequency of the respiratory move- ments occasionally occurs to a notable extent in the course of some diseases, and this de- serves the careful attention of the practitioner, as it is hkely to lead to very serious conse- quences.* The greater length of time that the respi- rations may be suspended without inducing insensibility, when a deep expiration followed by a deep inspiration has immediately pre- ceded, affords additional illustration of the procedure which a person ought to adopt when he wishes to suspend, during diving, &c., the respirations for the longest period consistent with his safety. The manner and the order in which the vital actions are brought to a stand when the chemical changes between the blood and the atmospheric air are arrested, have been discussed under the article AsPHYxiA.f six per cent, by volume of carbonic acid gas cannot exist in the air without danger to life, and that less than half this amount will soon be fatal, when it is formed at the expense of the oxygen of the air." (Opus cit. p. 54.) Leblanc ascertained that an ad- dition of 3 or 4 per cent, by weight of carbonic acid formed by the combustion of charcoal, and at the expense of the oxygen of the air respired, proved instantly fatal to dogs, while it required the addition of 30 or 40 per cent, of pm-e carbonic acid gas to the atmospheric air to produce the same effect. The great acti%-it3" of air deteriorated by the burning of charcoal in producing asphyxia, Leblanc attributes to the presence of carbonic oxide. He states that birds placed in air containing one per cent, of this gas, die in two minutes (Opus cit. pp. 240 and 24o). Legallois (Annales de Chimie et de Physique, tom. iv. p. 113. 1817) had pre^-iously performed experi- ments, from which it may be inferred that an addi- tion of somewhat more than 20 per cent, of carbonic acid to the atmospheric air, is sufficient to bring the evolution of carbonic acid from the blood in the lungs to a stand in the warm-blooded animals, and that, when the percentage of carbonic acid in the inspired air is increased to above 30, part of this gas is absorbed by the blood. * We have given some illustrations of this in pointing out the manner in Avhich division of the vagi nerves causes death. (Edinburgh Medical and Sm-gical Journal, vol. b. p. 298 to 302. 1839.) t We have published a series of experiments (Edinburgh Medical and Surgical Journal, vol. Iv. 1841) which go to support the account given of the manner in which the vital actions are arrested in asphyxia in the article referred to. In this we ob- tained satisfactory proof of the opinion of Bichat|upon the effects of the venous blood in suspending the sen- sorial functions. In an excelleiat experimental essay on this subject, published subsequently to our essay (EfUnburgh Med. and Surg. Jovu-nal, vol. Ixiii. 1845), the author maintains, in opposition to the doctrine laid down in the article Asphyxia, " that the flow of blood through the lungs is arrested in consequence of the venous blood acting as an excitant to the minute branches of the pulmonary veins and causing their contraction." In our experiments we foimd that, when the suspension of the respiration had been Experiments have been made by Nvsten*, by Mr. Macgregorf , Dr. Malcolm":J:, and by Hannover §, upon the quantity of carbonic acid gas evolved from the lungs in some diseases, but these have not yet been carried sufficiently far to furnish us with any practical or theoretical conclusions of importance. Differences between arterial and venous blood. — A knowledge of the chemical and physical differences between arterial and venous blood, or, in other words, between the blood imme- diately before and immediately after it has passed through the lungs and been subjected to the action of the atmospheric air, consti- tutes part of the data requisite for discussing the Theory of Respiration. Although many able chemists and physiologists have of late years directed their attention to this subject, yet, from its inherent difficulties, much discre- pancy of observation and conflicting evidence still require to be cleared up and reconciled. Most, if not all, of the comparative analyses of the venous and arterial blood hitherto pub- lished are of considerably less value for our present purpose than they may at first appear, since only those of the venous blood flowing from the right side of the heart, and the arte- rial blood flowing from the left side of the heart or along the arteries, ought properly to be taken into account. The blood returning along the veins of the abdominal viscera, and entering the heart by the cava inferior, differs in composition from that entering the heart by the cava superior, for, independently of other reasons, a quantity of water and certain sub- stances taken into the stomach are absorbed by the mesenteric and gastric veins. The composition of the blood in the large veins at the lower and lateral parts of the neck must also be somewhac affected by the lymph and chyle poured into that portion of the venous system. The analyses of venous and arterial blood taken at the same time from the carotid artery and the jugular vein, — the plan most generally followed in these researches, — are better fitted for throwing light upon the changes the blood undergoes in the perform- carried so far as to arrest the flow of blood through the lungs, the admission of atmospheric air was m- stantaneously followed by the renewal of the passage of the blood to the left side of the heart, — a fact in- compatible with this opinion, seeing that the blood- vessels are endowed •n-ith that kind only of con- tractihty which manifests itself by slow contractions and equalh- slow relaxations. * Recherches de Physiologic et de Chimie Patho- logique. Seconde section. 1811. t Edinburgh ^Monthly J oumal of Medical Science, vol. iii. p. 1. 1843. X Transactions of British Scientific Association, for 1840, p. 87. § De Quantitate relativa et absoluta Acidi Car- bonici ab Homine sano et fegroto exhalati. 1845. Hannover, in his experiments, employed the appa- ratus of Scharling, and was enabled to ascertain the absolute quantity of carbonic acid evolved from the body ; while the other experimenters ascertained its percentage only. There can be no doubt that the plan adopted by Hannover is the one which ought to be followed. " RESPIRATION. 357 ance of nutrition and secretion than of respi- ration. The most marked difference, more espe- cially in warm-blooded animals, between ar- terial and venous blood is that of colour, — arterial blood being of a scarlet red, and ve- nous blood of a dark Modena hue. The extent of this difference of colour between the blood in the arteries and in the veins varies in the diflferent vertebrata, and is greater in birds and in the mammalia than in reptiles and fishes ; and it tiho varies in different con- ditions of the body and surrounding media in the same animal. In animals exposed to artificial high temperatures*, or Hving in warm climates -f-, when the energy of the re- spiratory function is naturally diminished, the venous blood may be of a brighter colour than usual, while the arterial may be less so, and it may then be difficult to distinguish the one kind frdm the other. In certain cases of high febrile excitement of the circulation, as in acute rheumatism when the blood passes rapidly and abundantly through the lungs, the blood in the veins may be of a scarlet colour: on the other hand, where the aeration of the blood is imperfect, as during the state of hy- bernation, in certain diseases, or from some mechanical impediment to the free passage of the air into the lungs, the blood flowing along the arteries apj)roaches more or less the dark colour of venous blood. The temperature of the arterial blood in the left side of the heart, aorta, and large vessels springing from it, is higher than the venous blood by from 1° to 2° Fahr., according to Dr. John Davy $, and 1°-01 C (I°-818 Fahr.) on an average, according to Becquerel and Breschet.§ According to Dr. Davy, the ca- pacity of venous blood for caloric is 852, that of arterial blood 839. || The specific gravity of venous is somewhat greater than that of arterial blood. Dr. Davy gives the specific gravity of arterial blood as 1050, that of venous as 1053. If Some of those who have published analyses of both kinds of blood, procured more solid materials and less water from venous than from arterial blood ; others again have obtained the oppo- site result; while Denis, in his analysis of the blood of a dog, observed no difference in this respect. The number of instances, — taking the more trust-worthy analyses only into ac- * Crawford. Experiments and Observations on Animal Heat, p. 309. 3rd edit. t Dr. J. Davy. London Phil. Transact, for 1838, p. 28. X Researches, Physiological and Anatomical, vol. i. p. 147. 1839. At page 211 of the same volume, another series of experiments is given, in which the difference in temperatm-e varied from 1° to 3° F. § Annales des Sciences Natm-elles, 2me serie, tom. vii. p. 94. 1837. Becquerel and Breschet, in their experiments, used a thermo-electric apparatus. They found the difference of temperature between the two kinds of blood diminish as the blood-vessels are more distant from the heart. II Researches, Physiological and Anatomical, vol. i. p. 146. ' ^ b ^ Opus cit. vol. ii. p. 22. count, — where the quantity of water was greater in the arterial than in the venous blood decidedly prej)onderates. In all pro- bability the relative quantity of water in the two kmds of blood is determined by the rela- tive extent of the loss of that fluid by the arterial blood at the kidneys, lungs, skin, &c., and of the supply entering the veins from without, but chiefly through the mesenteric veins. A larger quantity of fibrin has been ob- tained by some analysts from arterial than from venous blood in man and in the domes- ticated animals; others again have procured a larger quantity from venous than from arterial blood; while a few have obtained dissimilar results in their analyses of these two kinds of bl jod in different genera of animals, and even in different individuals of the same species.* In the greater immber of the analyses, however, more fibrin was obtained from arterial than from venous blood, f According to Denis and Scherer, the fibrin of the two kinds of blood differs in regard to its solubility in nitre. When a portion of well-washed fibrin from venous blood is triturated with a third part of nitre, and four times its weight of water, and a small quantity of caustic potass or soda is then added, it dissolves into a gelatinous mass, having the chemical characters of albu- men ; while the fibrin from arterial blood si- milarly treated undergoes no such changes. The blood-corpuscles are more abundant in arterial than in venous blood, according to Prevost and Dumas, Lecanu and Denis ; ac- cording to Meyer, Hering, and Nasse, they are more abundant in the venous blood ; while the analyses of LeteUier and Simon tend to show that the proportion is fluctu- ating. According to Simon, the blood-cor- puscles of arterial contain less hasmatin than venous blood, while the quantity of globulin is variable. Mulder states that the chemical composition of haematin is the same whether derived from arterial or venous blood. t The statements made regarding the relative proportions of the albumen, fat, osmazone, and salts in the two kinds of blood, differ too much to justify us in attaching any importance to them, — a remark which, as yet, we are afraid applies with too much truth to most of the other statements regarding the che- mical difJerences between the two kinds of * Xasse (article Blut, in "Wagner's Handworter- buch der Physiologic, Band i. S. 171) states that the difficulty of conducting a coiTect quantitative analysis of the fibrine of the blood is sufficient to ac- count for these discrepancies. t We refer those who may •wish to obtain more detailed information upon this and some other points connected -with the chemical differences between the arterial and venous blood, with references to the different authors who have investigated this subject, to Nasse's Treatise, entitled Das Blut, &c., and the article by him in Wagner's Handworter- buch already referred to, and the first volume of Simon's Animal Chemistry, translated fcr the Sy- denham Society, by Dr. Day. X The Chemistry of Vegetable and Animal Phy- siology. Translated from the Dutch by Fromberg. Part XL p. 334. A A 3 358 RESPIRATIOxV. blood, mentioned above. Michaelis *, and Marcet and Macairef, in tbeir ultimate or elementary analyses of both kinds of blood, found more carbon and less oxygen in ve- nous, and less carbon and more oxygen in arterial blood; but Berzelius has adduced sufficient reasons to induce us to doubt whe- ther, in such investigations, at least as at present conducted, the distinctive characters of the two kinds of blood can be preserved during the analysis, and that they are de- serving of any confidence. J A larger quantity of fixed carbonic acid has been obtained from venous than from arterial blood by Mitscherlich, Gmelin, and Tiedemann.^ It is now placed beyond dispute that free gases exist in the blood, and it be- comes a point of great importance in de- ciding upon the true theory of respiration to ascertain their nature, quantity, and rela- tive proportions in the two kinds of blood. Four methods have been followed in pro- curing the free gases from the blood. 1. By the application of heat. 2. By the use of the air-pump. 3. By agitation of the blood with other gases. 4. By the respiration of other gases than atmospheric air. The first of these methods is imperfect, as the albumen coagulates when the temperature is raised towards the boiling point, and may retain gases present in the blood. The se- cond method is also liable to lead to negative results, unless the air-pump employed be of the best construction, for, according to Mag- nus, it is not until the pressure of the air •within the bell-glass is reduced to one inch, that the gases begin to escape from the blood. In such experiments it is also necessary to employ blood from which the fibrin has been removed, for coagulated blood will retain the free gases, and prevent their escape. Sir H. Davy stated that by raising the temperature gradually to 200 Fahr., he ob- tained from 12 cubic inches of the arterial blood of a calf I-l. cubic inch of carbonic acid gas, and -^-^ of a cubic inch of oxygen jj; and that he procured carbonic acid gas from human venous blood heated to 112 Fahr.t Enschut assures us that, by subjecting blood to the temperature of boiling water, he ob- tained carbonic acid gas both from venous and arterial blood, and a greater quantity from the former than the latter kind of _ * Diss. Inaug. de Partibus Constitutionis singiila- rium Partimn Sanguinis arteriosi et venosi. Berolini, 1827. t Aiinales de Chimie et Physique, torn. li. p. 382. 1832. X Lehrbuch cler Chemie, Band iv. S. 99, 100. Dresden, 1831. § Zeitschrift fiir Physiologie, Band v. 1833. Mit- scherlich, Gmehn and Tie'demann, by the addi- tion of acetic acid, and the appHcation of heat, ob- tained from 1000 parts of venous blood at least 12-3 parts, and from the same quantity of arterial blood 8-3 parts of combined carbonic acid. II Beddoes' Contributions to Physical and Medical Knowledge, p. 132. 1799. ^ Idem opus, p. 134. blood.* It is alleged that Brande obtained carbonic acid gas both from venous and ar- terial blood in considerable quantity by the use of the air-pump -j-; and Scudamore states that he procured it by the same means in variable quantities from venous blood. J Col- lard de Martigny^ and Enschut || procured carbonic acid gas both from venous and arterial blood, by placing them in the Torri- cellian vacuum, and a larger quantity from the former than from the latter. Nasse, sen.1I, Stevens**, Dr. G. Hoffman ff, Enschut i|, Dr. Maitland and BischofF|| || , obtained carbonic acid gas from venous blood on agitating it with hydrogen, or by allowing this gas to stand over the blood for several hours. The existence of free carbonic acid gas in the blood was still, however, regarded by some physiologists as very problematical, since se- veral trust-worthy and careful experimenters, such as Dr. J. DavylfH, Mitscherlich, Gmelin, * Dissertatio Physiologico-Medica de Respira- tionis ChjTnismo, p. 96 to 99. 1836. Enschut, in one set of experiments, obtained in this manner from 40 cubic centimetres (2-440 English cubic inches) of each kind of the blood of the calf, 2 to 4 cubic centi- metres (-12205 to -24410 English cubic inches) of cai-- bonic acid gas from venous blood, and 1 to 2-5 cubic centimetres (-061025 to -15256 English cubic inches) of the same gas from arterial blood, p. 99. Enschut points out various precautions necessai-}' to be ob- served to secure accuracy in such experiments, a want of attention to which, he beheves, was the cause of the failure of Dr. J. Da"\-^-, Miiller, and others, in their attempts to obtain carbonic acid gas from blood by heat, p. 100—104. t Sir Everard Home, in London Philos. Trans, vol. xxix, p. 172. 1818. It is stated by Sir Everard (p. 181), that Mr. Brande obtained carbonic acid in the proportion of 2 cubic inches for every ounce of blood, — a quantity so large, and obtained apparently with such facility, as to raise insuperable suspicions regarding the accuracy of the experiments. Sir Everard Home (29th vol. Philos. Trans, p. 189) and Scudamore state that they obser\-ed the escape of free carbonic acid gas from the blood during its coagulation, — an obsen-ation not confirmed by others. It appears that Yogel also obtained carbo- nic acid from venous blood by means of the air- pump. (Schweigger's Journal, Band xi. S. 401, as quoted bv Bischoff.) X An Essay on the Blood, p. 108. 1824. The largest quantity of carbonic acid gas that Scudamore procured from venous blood, was half a cubic inch of gas from six oimces of blood. § Magendie's Journal de Physiologie, tom. x. p. 127. 1830. II Opus cit. p. 115. ^ Meckel's Archiv, Band ii. 1816. Nasse al- lowed the hydi-ogen to stand over blood from 24 to 48 hours. ** Philos. Transact, vol. xlvi. p. 345. 1835. ft Medical Gazette, for 1832 — 1833, vol. xi. p. 881. XX Diss, de Eespirationis Ch^Tnismo, p. 124 to 126. Enschut obtained carbonic acid by this means also from arterial blood, but in smaller quantities than from venous blood. §§ Experimental Essav on the Physiology of the Blood, p. 52. EcUnburgh,^1837. nil Conmientatio de Xovis quibusdam Experi- mentis Chemico-Physiologicis ad illustrandam Doc- trinam de Respiratione institutis, pp. 17, 18. Hei- delberg, 1837. Bischoff also procured carbonic acid gas from arterial blood by means of the air-pump, pp. 11, 12. Philos. Trans, vol. xxxiv. p. 500. 1823. RESPIRATION. 3o9 and Tiedemann *, Stromeyer f , Miiller and others J. failed in obtaining any carbonic acid gas from the blood by the air-pump and other means, and it was not until the publication of the important experiments of Magnus, con- firmed as they have been to a certain extent by other observers, and strengthened by evi- dence collected both before and since on the results of the respiration of animals in hy- drogen and nitrogen gases, that the existence of any free gas in the blood has been gene- rally admitted. Bertuch and Magnus pro- cured carbonic acid gas from human venous blood by agitating it with hydrogen.^ Mag- nus has not only obtained carbonic acid gas from both kinds of blood in some of the domesticated animals, but also oxygen and azote by means of the air-pump. The two latter gases were also procured from both kinds of blood by agitation with carbonic acid gas. The quantity of gases obtained from the blood by the air-pump in these expe- riments by Magnus amounted to yVt-h, and sometimes to ith of the volume of the blood employed ; but from the difficulty of libe- rating the gases from the blood, he believes that this quantity forms but a small part of that actually held in solution in this fluid. In some experiments with hydrogen, the quan- tity of carbonic acid obtained amounted to ^th of the volume of the blood employed. The relative quantity of oxygen gas to the car- bonic acid gas is greater in arterial than in venous blood. In venous blood the oxygen was as Ath, and often ^th, while in arterial blood it was at least as -id and sometimes ^ to the carbonic acid.|| Magnus, in a second memoir on this subject, states that he obtained the following quantities of oxygen and nitrogen from the arterial blood of two old horses, by agitating it in carbonic acid gas : — Oxygen. Azote. 10*5 2*0 "1 per cent, of the volume 10 3-3J of blood employed.il By adding together the total quantity of gases collected from each kind of blood in his dif- ferent experiments by means of the air-pump, and then comparing the relative proportions * Loc. cit. t Dissertatio Libenxmne Acidum Sanguine con- tinetur. Gottingen, 1831. X Two at least of these experimenters, viz. Dr. Davy and Gmelin, have since satisfied themselves that carbonic acid gas is evolved from blood under the air-pump. Dr. Davy (Philos. Transact, for 1838, p. 291) obtained it in small quantities both from venous and arterial blood, and Gmelin (Pi-eface to BischofTs Commentatio de Novis quibusdam Experimentis, &c.) also in small quantity from venous blood. § PoggendorfF's Annalen der Physik und Chemie, Band xl. S. 583. 1837. 11 Idem opus. i Poggendoi-fF's Annalen, Band Ixvi. S. 202. 1845. Enschut had, previous to Magnus's experiments, obtained azote from both kinds of blood, and in greater quantity fi'om venous than from arterial blood. Opus cit. p. 159. of their constituent parts, the following results are obtained : — Arterial blood. Venous blood. Cubic Cubic centimJjtres. centimetres. Carbonic acid gas 39-5 or 62-3 per 47-5 or 71-6 per cent. cent. Oxygen - 14-7 _ 23-2 — 10-1 — 15-3 — Nitrogen* 9-2 — 14-5 — 8-7 — 13-1 — / The quantity of oxygen gas procured from the blood of calves, oxen, and horses, pre- viously agitated with atmospheric air, was not less than 10 per cent, and not more than VI per cent. The blood can, however, absorb a greater quantity of oxygen and nitrogen than was collected in the experiments last-men- tioned, for by repeatedly shaking blood with renewed quantities of carbonic acid gas to remove the whole of the oxygen and nitrogen gases it contained, and then agitating it in measured quantities of atmospheric air, he ascertained, by again measuring the atmo- spheric air, that the minimum quantity of oxy- gen absorbed amounted to 10 per cent., and the maximum to 16 per cent. The quantity of nitrogen procured in numerous experiments on the blood of calves, oxen, and horses, pre- viously agitated with atmospheric air, was, when reduced toithe temperature of 32 Fahr. and the mean barometric pressure, from 1*7 to 3'3 per cent, of the volume of the blood employed. The quantity of oxygen gas which blood is capable of absorbing from the atmo- spheric air, is, according to Magnus, from 10 to 13 times more than water can do under the same circumstances.f The experiments * Poggendoi-ffs Aimalen, Band Ixvi. S. 189. Gay Lussac (Annales de Chimie et de Physique, 3me serie, torn. x. p. 1. 1844), has brought forward va- rious objections against the inferences drawni by Magnus from his experiments. He asserts that they lead to the conclusion that more carbonic acid gas exists in arterial than in venous blood. I\Iag- nus has replied, and oii the whole successfully, to these objections of Gay Lussac (Opus cit. Baud Ixvi). He contends that as the quantity of gases procured was only a part of what the blood actually contained, and as the experiments were of tlifferent duration, it must lead to error to compare, as Gay Lussac has done, the relative quantities of carbonic acid gas obtained from corresponding quantities of the two kinds of blood; and that the legitimate mode of procedure under the circumstances of the case, is to compare, as has been done in the above table, the relative quantities of the whole of the gases procured fi-om each of the two kinds of blood. t Poggendoi-lf 's Annalen, Band Ixvi. S. 202. In some experiments the quantity of nitrogen absorbed by the blood, when previously agitated Avith carbonic acid, was G*5 per cent. Though these various results obtained by Magnus in his experiments have not been fully confinned by others, indeed several expe- rimenters, such as Enschut, Bischofl^, and Dr. J. Davy, who succeeded in procuring carbonic acid gas both from venous and arterial blood, failed in ob- taining decided e-\adence of the presence of oxygen gas, yet they appear to have been so carefully and repeatedly performed, that a behef in their general A A 4 360 RESPIRATION. of Dr. J. Davy, Mitscherlich, Gmelin and Tiedemann, Enschut and Magnus, prove that venous blood can absorb considerably more than its own volume of carbonic acid gas ; and according to Mitscherlich, Gmelin and Tiedemann, and Enschut, more of this gas can be absorbed by arterial than by venous blood * Lehmann has endeavoured to ascertain the relative quantities of free and combined car- bonic acid in the blood. In twelve experi- ments upon bullock's blood the average quan- tity of free carbonic acid in 1000 grammes (15433-0 Troy grains) of blood, was 0-132 gram. (1*937 grains) of free, and 0*6759 gram. (10-431 grains) of combined carbonic acid : or, estimating these quantities by volume, in 61 "250 English cubic inches of blood, there were 4*271 cubic inches of free, and 21"9G8 cubic inches of combined carbonic acid.'j' The results obtained on causing animals to breathe gases devoid of oxygen are in unison with those derived from direct experiment, and furnish additional evidence in proof of the existence of free gases in the blood. That a quantity of carbonic acid gas may be exhaled from the blood during the respiration of gases devoid of oxygen is proved by the experiments accuracy is justly almost universally entertained by physiologists. Marchand (Joui-nal fiir praktische Chemie, Band xxxv. S. 391) is the only other che- mist, as far as we are aware, who has procured oxygen gas from the blood. He ascertained, by qualitative but not by quantative analysis, that oxygen gas is contained in the venous blood of the dog. It has been argued, and the objection is antici- pated and examined b}^ Magnus, that part of the carbonic acid gas obtained from the blood in the above experiments may not have existed in the free, but in the combined state in the blood. It has been proved by the experiments of Heinrich Rose (Pog- gendorff's Annalen, Band xxxiv. S. 149. 1835), and Marchand (Journal fiir praktische Chemie, Band xxxv. S. 389, 390. 1845), that when a solution of bicarbonate of soda is agitated with, or even exposed for some time to, atmospheric air or hydrogen, it gives oif part of its carbonic acid, and becomes a sesqui- carbonate ; and if heat be now applied, an additional quantity of carbonic acid is given off, and it is re- duced to the state of carbonate of soda. If, there- fore, bicarbonate of soda exists in the blood, part of the cai'bonic acid gas obtained in the experiments of Magnus and others may have been derived from this source. The exact condition of the carbonates of soda in the blood is not known : indeed their ex- istence there has lately been called in question by Enderlin (Annalen der Chemie und Pharmacie, Band xlix. S. 317) and Liebig (idem opus. Band l\ni. S. 126. 1846), but Avithout sufficient reason, as Marchand (Journal ftir praktische Chemie, Band xxxvii. S. 321. 1846), Lehmann (idem opus, Band xl.), and Moleschott (HoUandische Beitrage, Band i. hedft ii. S. 163. 1847) have shoAvn. * Dr. J. DaA^ (Philos. Transact, for 1838, p. 298) has made an important observation on the absorbing capacity of the blood for carbonic acid under different circumstances. In two animals, one of which was killed by strangulation, the other by exhaustion of the air of the lungs by the air-pump, the blood of the former absorbed only 150 per cent., that of the latter 370 per cent. t Journal fiir pi-aktische Chemie, von Erdmann und ^larchand, Band xl. S. 133. 1847. of Spallanzani* and Dr. W. F. Edwards f on the products of the respiration of snails con- fined in hydrogen and azote ; those of Dr. W. F. Edwards J on a fish (Cyprinus aureus) confined in water saturated with hydrogen ; those of Dr. W. F. Edwards §, Col lard de Mar- tignylj, Miiller and Bergemann^I, Bischolf** and Marchand "j"!", on frogs confined in hy- drogen or azote ; and those of Dr. W. F. Edwards IJ, upon the young of certain of the mammalia confined in hydrogen gas. The experiments of Nysten in which he first exhausted the air, as far as possible, in the lungs of adult dogs, and then caused them to breathe hydrogen or azote ; and those of Sir H. Davy || || , and of Coutanceau and Nysten Ifl, on the respiration of nitrous oxide and azote in their own persons, though not free from serious objections, are still, as far as they go, in favour of the opinion that free carbonic acid gas is contained in the blood. In a former part of this article we have de- tailed several observations, both upon the human species and the lower animals, to prove that a quantity of azote is frequently exhaled in respiration. The experiments of Allen and Pepys***, and Nysten fff, show that the exhalation of azote is considerably increased by breathing oxygen or hydrogen, or a mixture of these two gases, and thus afford additional evidence that free azote exists in the blood. Marchand concludes from his experiments on frogs, that when they are made to breathe pure oxygen gas, azote is evolved from the blood, and that when made to breathe pure hydrogen, both oxygen and azote are evolved from the blood. J J j Differences in the form of the red corpuscles in venous aiid arterial blood. — The physical * Me'moires sur la Respiration, p. 846 to 351. t De r Influence des Agens Physique sur la Vie, p. 449. 1824. X Opus cit. p. 447, 448. § Opus cit. p. 442 to 447. II Magendie's Journal de Phvsiologie, tom. x. p. 122 to 124. ^ Muller's Elements of Physiology, translated by Baly, vol. i. p. 354. ** Commentatio de No vis quibusdam Experi- mentis Chemico-Physiologicis, p. 20. ft Journal fiir praktische Chemie, Band xxxiii. S. 154. 1844. Marchand thinks that in the experi- ments of those who preceded him, upon the respira- tion of frogs in hydrogen, that the gas employed must have contained some oxygen, as the animals lived longer than those used in his experiments where the gas was quite pure. XX Opus cit. p. 453 to 455. §§ Recherches de Physiologic et de Chimie Patho- logiques, p. 225 to 229. II II Researches, Chemical and Philosophical. Divi- sion II. Coutanceau's Revision des Xou velles Doctrines Chimico-Physiologiques, p. 280 to 302. 1821. Cou- tanceau and Xysten breathed azote alone ; and their experiments were regarded, even by Coutanceau himself, as " essais bien incomplets." Opus cit. p. 301, 302. *** Philos. Trans. 1809, p. 404. ttt Recherches, &c. p. 230, 231. XXX Opus cit.Band xxxiii. S.154 — 159. Band xxxv. S. 386—389. Marchand does not distinctly state that he ascertained this by direct analysis of the expired gases. RESPIRATION. 3(51 conditions of tlie red corpuscles can be changed by the action of various agents, such as pure water, and solutions of certain neutral salts. By the action of the former, the corpuscles swell, become more globular, and reflect less light ; by the action of the latter, they become smaller, thinner, somewhat bent and notched, and reflect more light. These changes are apparently dependent upon endosmotic and exosinotic currents, between the fluid contents of the red corpuscles and the surrounding fluid. It has been maintained that the red cor- puscles of venous and arterial blood differ in their external form, — the former approaching in their shape those acted upon by water, the latter those subjected to the action of solutions of the neutral salts ; and this change in the form of the corpuscles has been adduced as the cause of the difference; in colour between arterial and venous blood. Kaltenbrunner *, Schultzf, H. Nasse |, Scherer^, Renter ||, Mr. Gulliver If, and Harless **, have de- scribed various differences in the external form of the red corpuscles of the two kinds of blood, as observed by them under the microscope, from which some of them infer an increase in their power of reflect- ing light ft ; while BurdachtJ, Miiller Bruch II II, and Marchand tlf, have failed in de- tecting by the micoscopeany difi^erence in their external form in the two kinds of blood.*** Those observers who have described differ- ences in the shape of the red corpuscles in arterial and venous blood do not quite agree in their account of these. They agree, how- ever, in this, that the red corpuscles are * Experimenta circa Statum Sanguinis et Vaso- rum in Inflammatione, p. 71. 1826. t Das System der Circulation, S. 27. 1836. X Handworterbuch der Physiologie, von Wagner, Band i. S. 97. 1842. § Zeitschrift Fiir Eationelle Medizin. Herausge- geben von Henle und Pfeufer, Band i. heft ii. S. 288. 1843. II Idem opus, Band iii. heft ii. S. 165. 1845. ^ Work of Hewson, printed for the Sydenham Society, note at p. 9. 1846. * * Monographic iiber den Einfluss der Gase auf die Form der Blutkorperchen, von Rana temporaria. Erlangen, 1846. tt ^^^e have not included, for obvious reasons, among these authorities in favour of there being a difference in the shape of the red corpuscles in the tAvo kinds of blood, those authors who, like Henle and Mulder, have adopted this view without stating that they had personally investigated by the micro- scope the point at issue. XX Traite de Physiologie, &c. traduit par Jourdan, torn. vi. p. 135, 136. 1837. §§ Elements of Physiology, translated by Baly, vol. i. p. 346. 1840. III Zeitschrift, &c. Von Henle und Pfeufer, Band i. heft iii. S. 440. 1844 ; Band v. heft iii. S. 440. 1847. Journal fur praktische Chemie, Band xxx^dii. S. 279. 1846. *** Dr. G. O. Bees (INIed. Gazette, Session 1844-5, p. 840) maintains that the structure of the red par- ticles prevents the possibility of their assuming any other form than the biconcave in a fluid of the specific gravity of serum, whether exposed to air or not ; but this statement appears to be founded upon the presumed efiects of the endosmotic and exosmo- tic conditions of the red corpuscles, and not upon any examination by the microscope of the effects of gases upon these bodies. more turgid and less clear in venous than in arterial blood. Scherer describes the red corpuscles in arterial blood as biconcave, and those in venous blood as biconvex and de- cidedly swollen. Mr. Gulliver states that in all his experiments " the red corpuscles were reduced in size, both in breadth and thickness, by neutral salts, and in a less degree by sugar and oxygen ; while the first effect of water and of carbonic acid was to swell the cor- puscles and make them more globular." Nasse says that the red corpuscles of the arterial blood in the mammaliii, on the contact of car- bonic acid gas, become muddy in the middle, the ring formed by the colouring matter be- comes broader, they become darker and some- what thicker, at least on one side, and they adhere closer together. Harlass gives measure- ments of the corpuscles of the blood of the frog, when brought into contact with oxygen and carbonic acid, to show that they become somewhat broader and thicker when exposed to the action of the latter gas. He also states that while the corpuscles in the former are finely granulated on the external surface, those in the latter are smooth. Theory of resj)iraf.ion. — The actions be- tween the blood and the atmospheric air in the performance of the function of resj)iration are regulated entirely by chemico-physical laws. No doubt the blood and air are con- veyed to and from the lungs through the in- strumentality of the vital properties of the nervous and muscular tissues, but the changes they there undergo do not appear to be in- fluenced by vitality. When venous blood and atmospheric air are brought into contact out of the body, the same actions apparently occur as in the lungs during life, viz., the atmospheric air loses part of its oxygen, acquires in its place a quantity of carbonic acid gas, and the blood assumes the arterial hue. The distri- bution of the blood in innumerable minute streamlets upon the surface of the air-cells, filled with atmospheric air, affords much more advantageous means than can be obtained in experiments out of the body, for facilitating the mutual actions of the blood and atmo- spheric air. From the known rapidity with which gases permeate both living and dead animal membranes, the moist delicate mem- branes that intervene between the blood con- tained in the capillaries of the lungs, and the atmospheric air in the air-cells, will readily permit the endosmose of a portion of the at- mospheric air, and the exosmose of a portion of the gases held in solution in the blood. The rest of our remarks on the theory of respiration maybe arranged under three heads : viz. 1st, the manner in which the air in the upper and in the lower parts of the respiratory apparatus is intermixed ; 2dly, the nature of the immediate actions betw^een the blood and atmospheric air in the lungs, in which a quan- tity of carbonic acid gas appears in the expired, and a quantity of oxygen disap()ears from the inspired air ; 3dly, the nature of the changes the blood undergoes in passing from the venous to the arterial condition. 362 RESPIRATION. On the manner in which the air in the upper and lower parts of the respiratory ajyparatiis becomes intermixed. — The respiratory qualities of the other parts of the inner surface of the air-passages must be very feeble when com- pared with the membrane of the air-cells of the lungs ; and there can be no doubt that almost all the carbonic acid present in the ex[)ired air is derived from the blood circula- ting in the capillary blood-vessels of the air- cells ; and that this evolution of carbonic acid gas is continuous, going on during expiration as well as during inspiration. As a portion only of the atmospheric air, probably not much more than a fourth or a fifth part, is re- newed at each ordinary respiratory movement when the body is in a state of rest, the air expelled during expiration will chiefly consist of that occupying the larynx, trachea, and the larger bronchial tubes ; so in the same man- ner, the air drawn in by inspiration will chiefly occupy the same parts of the respira- tory apparatus. It is well known that the air expelled in the first part of an expiration contains less carbonic acid than that expelled towards its close ; thus the air in the deeper parts of the respiratory apparatus must be richer in carbonic acid and poorer in oxygen than that in the upper parts. The amount of intermixture of the gases in the different parts of the respiratory apparatus effected by the muscular movements of the chest would, in all probability, be too imperfect for the proper arterialisation of the blood, were this not aided by the well-known tendency of gases to diffuse themselves through each other. As the air in the air-cells differs from that in the higher parts of the respiratory apparatus in containing more carbonic acid and less oxy- gen, the nitrogen being nearly the same in both, this diffusion of gases is probably chiefly confined to the two former. From the oxy- gen being of lighter specific gravity than the carbonic acid gas, the descending current of oxy gen gas will exceed the ascending current of carbonic acid, and 81 parts of carbonic acid will be replaced by 95 of oxygen, for according to the law regulating the diffusion- volumes of gases under such circumstances, established by Graham, in the case of each gas this is inversely proportional to the square root of its density.* On the nature of the actions between the blood and the atttwspheric air in the lungs, by vihich a quantity of oxygen is removed from the inspired air, and a quantity of carbonic acid gas added to the expired air. — Four views have been maintained on this point. — 1. That of Lavoisier, La Place, and others; that the oxygen which disappears from the inspired air unites directly in the lungs with hydro- carbon furnished by the venous blood, and forms the carbonic acid gas and watery vapour that escape along with the expired air.f * Edinbiu-gh Transactions of Royal Society, vol. xii. p. 573. 1834. t Seguin and Lavoisier " Sur la Transpiration des Animaux," in Memoires de I'Academie des 2. That of La Grange and Hassenfratz; that free carbonic acid gas is present in a state of solution in the venous blood before it arrives at the lungs, where this gas is ex- haled ; that nearly the whole of the oxygen gas abstracted from the inspired air is absorbed at the lungs, and held in solution by the arterial blood ; and that the combination of the oxygen with the carbon and formation of carbonic acid chiefly take place when the blood is passing through the capillaries of the systemic circulation.* 3. That the oxygen that disappears from the inspired air enters into chemical combina- tion with one or more of the constituent parts of the blood in its course through the lungs, that in the passage of the blood through the capillaries of the systemic circulation this oxygen leaves the substance or substances to which it had united itself, and combines with carbon to form carbonic acid, or with carbon and hydrogen to form carbonic acid and water, and that the carbonic acid thus formed does not combine chemically with any of the constituent parts of the venous blood, but is held in solution by it, and is evolved while passing through the capillaries of the lungs. 4. That not only the oxygen that disap- pears from the inspired air is united chemi- cally in the arterial blood, but also the carbonic acid formed during its circulation through the systemic capillaries enters into chemical combination with some one of the constituent parts of the venous blood ; that the combination thus formed is decomposed in the pulmonic capillaries by the agency of the absorbed oxygen, and the carbonic acid thus set free is evolved and escapes in the expired air. The first view, viz. that the carbonic acid that appears in the expired air is formed in the lungs by the combination of part of the oxy- gen of the inspired air with the carbon of the venous blood, must now be regarded as unte- nable. The existence of free gases in the blood, the evolution of carbonic acid from the blood at the lungs in animals made to breathe gases devoid of oxygen, the small increase of Sciences for 1790, p. 601. It is still maintained by some chemists and physiologists, Avho appear to re- gard the fmiction of respiration simply as a process of combustion, but who do not uphold the opinion that this combustion takes place in the hmgs and that the watery vapom- in the expired air is imme- diately derived fi-om this soiu-ce, that a part of the oxygen that disappears from the inspired air vmites with hydrogen to form water. No satisfactors' evi- dence is offered in support of this opinion, and in the present state of our knowledge it must be re- garded as a mere conjecture. * This doctrine, as propounded by Hassenfratz (Annales de Chimie, tom. ix. p. 261.* 1791), which has received various modifications since his time, was based on the ^•iew that the purjile colour of the venous blood is the result of the combination of oxygen vdih. the carbon and hydrogen of the blood, while the scarlet colour of arterial blood is caused by the solution of oxygen gas in it, and consequently there can be little combination of the carbon and hydrogen of the blood Anth the atmospheric air in the lungs. RESPIRATION. 363 temperature the blood acquires in its change from the venous to the arterial condition *, and the result of observations made upon the blood out of the body, when subjected to alternate applications of oxygen and carbonic acid gas, are all opposed to the supposition that the formation of carbonic acid gas takes place to any great extent in the lungs. The existence of a quantity of free carbonic acid in the venous blood, more than sufficient to furnish the whole of this gas thrown off at the lungs, and the avowedly conjectural explana- tion of the manner in which the carbonic acid is combined and the agency by which its com- binations are decomposed in the lungs, given by those who advocate this view, justify the adoption of the opinion that the carbonic acid gas evolved at the lungs exists in a free state in the venous blood before it reaches the lungs. An interchange, therefore, takes place be- tween the air in the cells of the lungs and the blood in the pulmonic capillaries, the latter receiving oxygen and giving up part of the free carbonic acid held by it in solution. These gases, from their solubility, readily per- meate the thin moist membranes interposed between the blood and the atmospheric air contained in the cells of the lungs. We have already mentioned that Valentin and Brunner have concluded from their experinients that this interchange of oxygen and carbonic acid gas is regulated by the law of the diffusion of gases established by Graham ; but besides the objections that may be urged against this view, drawn from the considerable diversity in the relative proportions of these gases inter- changed during respiration as ascertained by different experimenters, the conditions under which the two gases are placed in respiration are very different from those in the experi- ments instituted by Graham. f In respiration the gases are separated by moist animal mem- branes, and one of these, viz. the carbonic * Dr. J. Davy ascertained (Lond. Pliilos. Trans, for 1838, p. 298) that oxygen gas shaken with ve- nous blood out of the body raised the temperature of the latter from 1° to 2° Fahr. Marchand (Journal fiir praktische Chemie, Band xxxv. S. 400) adduces reasons for believing that this increase in temper- ature arose from the mere absorption of the gas, and not from any chemical action between it and the blood. t Graham's first experiments, from which he de- duced his law that " the diffusive velocities of dif- ferent gases are invei*sely as the square root of their densities," were made by interposing a porous sep- tum of stucco between the gases experimented upon and the external air. The equivalent diffusion-vo- lumes of oxygen and carbonic acid calculated ac- cording to this theory, with which the experimental results closely agree, are — air being equal to 1, ox3-gen 0-9487, and carbonic acid 0-8091. (Trans- actions of Royal Society of Edinburgh, vol. xii. p. 222. 1834.) In some later experiments Mr. Gi*a- ham ascertained that this law also held when gases pass through minute apertures in a thin plate into a vacuum, while, on the other hand, the discharge of the same gases through tubes into a vacuum has no uniform relation to the density of the gases. (Philosophical Transactions of London for 1846, p. 373.) acid, is held in solution in a fluid subjected to an increased pressure caused by the action of the heart.* We are not, in the present state of our knowledge, in a condition to form any thing like an accurate estimate of the various cir- cumstances which regulate this interchange between the oxygen of the air and the car- bonic acid gas of the blood, but it is obvious that it will be affected in a most important manner by the relative proportion of these gases in the air contained in the air-cells of the lungs and in the blood, and by the quan- tities of atmospheric air and blood trans- mitted through the respiratory apparatus. We have seen, from the experiments of Vierordt, that when the air is rapidly renewed in the lungs, though the percentage of car- bonic acid in the expired air is dnninished, yet the total amount of this gas thrown off from the lungs within a given time is pro- portionally increased ; while, on the other hand, when the respirations are diminished below the natural standard, though the per- centage of carbonic acid in the expired air is increased, yet the total quantity thrown off from the lungs in a given time is propor- tionally diminished. When the atmospheric air in the lungs is rapidly renewed by an in- creased frequency of the respiratory move- ment, the diffusion of the oxygen in the higher, and of the carbonic acid in the deeper, parts of the air tubes will proceed more ra{)idly, and the air in the deeper parts or in the air-cells will contain a less percentage of carbonic acid, and a greater percentage of oxygen, than when the respirations are carried on with the usual frequency and force. This diminution of the usual quantity of carbonic acid gas and increase of oxygen in the deeper parts of the lungs will accelerate the inter- change between the oxygen of the air and the carbonic acid of the blood, provided the blood holds its normal amount of free gases in solu- tion, and a larger quantity than usual of car- bonic acid will be separated from the blood at * The passage of gases through moist membranes is not simple diffusion, as it is influenced by the solubility of these gases in the fluids of the mem- branes. In the case of respiration it will also pro- bably be affected by the attractive force of the constituents of the blood for the gases. The relative rapidity of the passage of different gases through membranous septa, as observed in the experiments of Dr. Faust and of Mr. Mitchell (American Journal of the INIedical Sciences, Nov. 1830), and by other experimenters, is not in accordance ^ith the law of the diffusion of gases, as determined from experi- ments upon their diflusive velocities through porous septa into the atmospheric air, and through minute apertures in a thin plate into a vacuum. "When a bladder filled vnth oxygen gas is introduced into a vessel full of carbonic acid gas, the latter passes so much more rapidly through the coats of the bladder than the former, that the bladder becomes gradually distended, and at last may burst. In these last expe- riments, equally as in those of Graham, the condi- tions under Avhich the diffusion of the gases occurs, are not the same as those in respiration ; and Ave find the carbonic acid gas passing in greater quantity through the organic membranes than the oxj-gen, — the reverse of what takes place in respiration. 364 RESPIRATION. the lungs, and carried out in the expired air. If, then, we add an increased flow of blood through the capillaries of the lungs to an in- creased frequency of the respiratory move- ments, as occurs in exercise, the interchan_'e between the oxygen of the air and the free carbonic acid of the blood will be carried on with greater activity. When, on the other hand, the air is renewed in the lungs less fre- quently than usual, as happens when the respiratory movements are diminished in number and in extent, the air in the deeper parts of the lungs will contain less oxygen and more carbonic acid than usual, and the interchange between the oxygen of the atmo- spheric air and the free carbonic acid of the blood will proceed more slowly. When the respirations are reduced to about one half of their normal frequency, as occurs in the course of some diseases, and after division of the vagi nerves, the carbonic acid gas gradually accumulates in the blood, less oxygen is ab- sorbeJ, and the individual generally sooner or later dies of asphyxia. When the quantity of carbonic acid gas in the air-cells reaches a certain amount, the evolution of this gas from the blood wi.l cease ; and when this is carried still farther, there will be an absorption of a part of the carbonic acid gas by the blood. The interchange between the nitrogen and the other gases at the lungs is very small in the normal condition of the respiration, but there is every reason to believe that this is regulated by circumstances similar to those which determine the interchange of the oxygen and carbonic acid. The nitrogen is much less soluble in the blood than the oxygen and carbonic acid, and we presume that its power of permeating moist animal membranes is much inferior to these gases, and that the smaller quantity of it held in solution in the blood may be in this manner explained. We have already pointed out that, in the experi- ments made to determine whether nitrogen is absorbed or exhaled at the lungs, opposite results have been obtained, but that the evi- dence preponderates in favour of the opinion that a small quantity of this gas is evo'.ved from the blood during respiration. By an alteration of the usual relation between the quantities of nitrogen present in the air and in a free state in the blood, the evolution of nitrogen from the blood may be increased or suspended, or it may be absorbed by the blood instead of bemg evolved by it. In a previous part of this article we have referred to ex- periments which prove that when animals breathe oxygen or hydrogen gases, or a mix- ture of both, azote is evolved in greater quantity than usual from the blood in the lungs; and that when they breathe azote alone, part of this gas is absorbed at the lungs. The exact condition in which the whole of the oxygen absorbed at the lungs exists in the biood, notwithstanding the light thrown upon this point by recent researches, is still not free from considerable difficulties. Pre- vious to the experiments of Magnus upon the gases of the blood, already referred to, the opinion of Le Grange and Hassenfratz, that the greater part of the oxygen gas absorbed at the lungs is dissolved in the blood and carried along with it in that condition to the systemic capillaries, was considered untenable by many celebrated ph} biologists, the more especially as the attempts to detect free oxygen in the arterial blood had failed in ali the more trust-worthy experiments. Different opinions as to the kind of chemical combination formed by the oxygen in the arterial blood have been entertained by those who believe that the portion of this gas that disappears from the inpired air does not unite with car- bon in the lungs to form carbonic acid, and that little or none of it is simply dissolved in the arterial blood. In the greater number of these hypotheses, however, the oxygen is supposed to unite itself in whole or m part to the red corpuscles, and especially to the iron contained in these: and as the exact state in which the metal exists in the red corpuscles is still undetermined, this has given rise to very different notions regarding the changes effected upon it by the oxygen. According to other views, the oxygen in whole or in part is united chemically to some of the other constituent parts of the arterial blood, and from these it is again separated in passing through the systemic capillaries, and unites with carbon to form carbonic acid.* * "We shall here very shortly notice a few of the more recent theories of respiration, which proceed on the supposition that the oxygen abstracted from the inspired air is combined, in whole or in part, with some of the constituents of the arterial blood. Gme- Un, Tiedemann, and MitscherUch (Zeitschrift fur Physiologie, Band v.) supposed that the oxygen absorbed at the lungs partly unites with carbon and hydrogen to form carbonic acid and water which are there exhaled, and partly with organic substances in the blood to form acetic and lactic acids : that these acids decompose some of the car- bonates of soda brought to the lungs in the venous blood, and that the carbonic acid thus set free is also exhaled. The arterial blood in its course through the tissues, more especially those of the kidneys and skin, loses part of its acetic and lactic acids ; and the soda with which they were combined, being set free, unites with the carbonic acid formed during the process of nutrition, and these carbonates are again decomposed in the lungs in the manner de- scribed. Dumas (Statique Chimique des Etres Or- ganises, pp. 43, 44, ome e'dit.) believes that the absorbed oxygen combines with certain matters of the blood and forms lactic acid, the lactic acid com- bines with soda to form lactate of soda, and this latter salt, by a real combustion, is converted into carbonate of soda, which is decomposed in its turn in the limgs by a fresh portion of lactic acid. Liebig (Organic Chemistry of Physiology and Pathology, edited by Gregory, p. 265. 1841)"supposes that car- bonate of protoxide of iron exists in the red cor- puscles of venous blood, and that in its piissage through the lungs, a large portion of the absorbed oxygen unites with it, forms hydrated peroxide of iron, and sets the carbonic acid free. !Miilder (The Chemistry of Vegetable and Animal Physiology, translated by Fromberg, Part II. p. 337) affirms that an alternate" change into carbonate of the protoxide of iron and peroxTde of iron in respiration is impos- sible, and maintains that the absorbed oxygen com- bines with the proteine compoimds of the blood and forms oxy-protelae, which being conveyed by the RESPIRATION. 365 The presence of a larger quantity of free oxygen gas in the arterial blood than what is sufficient to form the carbonic acid gas evolved at the lungs, amounting in some cases to rather more than 10 per cent, of the vo- lume of the blood in the experiments of Magnus, naturally leads to the conclusion that the greater part, at least, of the absorbed oxygen is not chemically combined in the arterial blood, and is simply held in solution by it. We are not, however, quite prepared to concur in the opinion of Magnus, that the whole of the absorbed oxygen is held in solu- tion in the arterial blood, and that an inter- change between part of the free carbonic acid of the venous blood, and part of the oxygen of the atmospheric air, embraces the entire changes in the blood as it passes from the venous to the arterial condition : for, if the opinion be correct that the elaboration of the materials of the chyle into blood is completed in the lungs, and that certain marked differ- ences in the fibrin of the two kinds of blood, noticed above, really exist, something more than this is probably necessary. Though the experiments of Marchand appear to prove that the absorbed oxygen does not enter into any chemical combination with the consti- tuent parts of the arterial blood in the lungs, by which carbon^"c acid gas is formed ; yet, while the greater part of the absorbed gas is held in solution in the arterial blood, a small portion of it may enter into chemical combi- nation in a manner hitherto not definitely ascertained.* It is almost universally believed that the free carbonic acid gas in the blood is formed by the combination of the absorbed oxygen with carbon in the blood, chiefly if not en- arterial blood to the capillaries is decomposed during the nutritive processes, and carbonic acid is formed and held in solution in the blood. [Dr. G. 0. Rees has lately put forward the following ingenious theory of respiration. He finds by analysis that the corpuscles of venous blood contain fatty matter in combination with phosphonis, which does not exist in arterial blood, or, at most, is found in it only in very small quantity. In respiration the oxy- gen of the inspired air unites with this phosphorus and fatty matter, and a combustion of it takes place, of which the products are water and carbonic acid, from the union of the oxygen with the elements of the fatty matter, and phosphoric acid, from the union of the oxygen with the phosphorus. The carbonic acid and water are exhaled, and appear in the expired air ; the phosphoric acid attracts the soda of the liquor sanguinis from its combination with albumen and lactic acid, and thus forms a tribasic phosphate of soda, a salt which possesses in a marked degree the property of giving a bright colour to hsematosine. See Dr. Rees' paper in the Lond. Edin. and DubL Phil. Mag. for July, 1848. — Ed.] * Marchand (Journal fiir praktische Chemie, Band XXXV. S. 385. 1845) in his experiments foimd that oxygen gas does not unite with fibrin to form car- bonic acid until it has been exposed to its action for some days, in fact not until it is passing into a state of putrefaction; and that, on subjecting to a conti- nuous current of oxygen gas, the red corpuscles, and beaten venous blood, after all the free carbonic acid held in solution had been carefully separated by the air-pump and agitation with hydrogen, no carbonic acid gas was evolved. These experiments invaUdate tirely in the course of its circulation through the systemic capillaries ; but this opinion, however plausible it may appear, and though it apparently accounts for the evolution of animal caloric in a satisfactory manner, does not rest upon any direct evidence. There are no facts that militate against the exist- ence of such a combination, and there can be no doubt that in the present state of our knowledge it affords the readiest and most complete interpretation of the phenomena referred to it, but still it is quite possible that the carbonic acid may be formed during the process of nutrition differently from what is generally supposed. Cause of the change of colour in the blood. — The manner in which the changes of colour in the blood is effected as it passes through the pulmonic and systemic capillary vessels, has not yet been satisfactorily determined. It seems now to be pretty generally admitted that the hosmatosine or colouring matter of the blood is enclosed within the enveloping membrane of the red corpuscles ; that this haematosine, though it may be combined with iron, does not derive its colour from the pre- sence of this metal ; and that all attempts to explain the change in the colour of the blood in the lungs by the formation of certain oxides and salts of iron must be abandoned. It is well known that various substances, besides ox3^gen gas, can impart a bright red colour to venous blood when mixed with it, and without being attended with any evo- lution of carbonic acid gas. The best known of these are solutions of the sulphate of soda, nitrate of potass, phosphate of soda, carbon- ate of soda, carbonate of potass, and sugar. The opinion of Stevens *, that the change from the venous to the arterial hue in the blood is to be attributed to the actions of the salts dissolved in the blood upon the haemato- sine, after the removal of the free carbonic acid of the venous blood through the attrac- tive force of the oxygen of the atmospheric air, has not been confirmed by subsequent researches. It has been ascertained that the removal of carbonic acid from venous blood, by means of the air-pump -j-, or by agitation the inferences in favour of the opinion, that the oxygen absorbed at the lungs partly enters into combination with the constituents of the blood in the lungs and forms or bberates carbonic acid gas, drawn fi'om the experiments of Scherer (Annalen der Che- mie und Pharmacie, Band xl. 1841) upon the action of oxvgen gas upon fibrin, and those of Berzehus (Lehrbuch der Chemie, Band iv. S. 94. 1831), and Maack (De Ratione quje Colorem Sanguinis inter, &c., p. 35. KiHfe 1834) upon the greater absorbing power for oxygen of the colouring matter of the blood over the serum. Mulder (Hollandische Beit- rage, &c. Band i. heft i. B. 20. 1846) adduces various arguments to show that the experiments of Magnus, and they apply equally to those of Marchand, by no means prove that a part of the oxygen absorbed at the lungs does not enter into chemical combination with the constituents of the blood before it reaches the capillaries of the systemic circulation. * London Philos. Transact, vol. xlvi. p. 345. 1835. t Dr. J. Davy and others. 366 RESPIRATION. with hydrogen gas * and the addition of a sahne solution, of the same strength as that existing in the blood -|-, will not impart to it the arterial hue, if oxygen gas be not at the same time present. The oxygen gas, there- fore, acts directly, and not indirectly by re- moving the carbonic acid, in changing the colour of the blood ; but as a small quantity only of this gas is sufficient, when the salts are present in their usual quantity, to produce this effect J, the action of the oxygen, in changing the colour of the blood in respira- tion, will be aided by the presence of the salts. In the present state of our knowledge, there is some difficulty in deciding whether the reddening of the blood by the absorbed oxygen be entirely a physical action, or whether it be partly physical and partly che- mical, seeing that several accurate observers, who have recently investigated this point, have arrived at very different conclusions. The opinion, first promulgated by Dr. Wells ^, that the change from the venous to the arterial hue arises from an increased re- flection of light in the red particles, caused by the presence of the absorbed oxygen, and without any chemical change upon the haema- tosine, has of late obtained several supporters. Those who have adopted this view do not, however, agree in their explanation of the manner in which this increased reflection of light is effected; some maintaining that it arises from an alteration in the form of the red corpuscles, and that this change consists in the biconvex corpuscles of the venous blood, becoming biconcave in the arterial blood II ; while others believe that the action of the ox3'gen on the blood is analogous to that of the nitrous oxide on the solutions of * Bischoff, Dr. Maitland, Xasse, and Marchand. t Gregory and Irving (vide London ^Medical Ga- zette, vol. xui. p. 814. 1831:). Xasse (Wagner's Handworterbuch,&c., Bandi. S. 182) affirms that even concentrated solutions of mvuiate of soda, nitrate of potassa, and carbonate of potass, cannot impart the true arterial hue to venous blood, without the pre- sence of a small quantity of oxygen ; and that when Stevens saw the blood redden under the air- pump, there must have been sufficient oxygen still present in the rarefied air to act on it with the aid of the salts. X Xasse (opus cit. p. 182). He also infers from his experiments that oxygen can redden the blood without the presence of salts (p. 187). § London Philos. Transact, for 1797, p. 41G. II Scherer, E enter, and Gulliver. Mulder (The Chemistry of Animal and Vegetable Physiology, p. 341, 342.) also contends that the arterial hue depends upon the red particles assuming the bicon- cave form and reflecting more light, but he gives a verv different explanation of the cause of the change inthefoi-mof the red particles from the other support- ers of this view. According to Mulder, part of the oxygen absorbed miites with some of the proteine compounds in the blood in the limgs, and forms oxy- proteine, and this furnishes a thin envelope to the red coi-puscles, and by its contraction causes them to assume the biconcave form. This opinion is sup- ported neither by direct observation nor by experi- ment. Marchand (Journal fur praktische' Chemie, Band xxxviii. § 276, 277) and Dimias (Comptes Eendus for 1846, torn, xxii, p. 900) after separa- the salts of iron, changing their colour with- out entering into chemical union with them.* We may, in the meantime, conclude that the change in the blood from the venous to the arterial hue in the lungs, is a physical and not a chemical action ; and that though there is pretty strong e\'idence in favour of the opinion that this physical change consists in an alteration of the form of the red corpuscles, yet it is not free from doubt. The various systematic works on Physiology are not included in the following Bibliography of Re- spiration. BiBLiOGRAPHT. — Mayow, Tractus Duo, quonun prior agit de Eespiratione : alter de Eachitide, Oxon. 1669. Lower, Tractus de Corde, &c. Caput iii. De Colore Sanguinis, Lugduni, 1722. Priestley, Observations on Eespiration and the Uses of the Blood, in Philos. Transact, of London for 1776. Lavoisier, Experiences sur la Eespiration des Ani- maux, et sur les Changemens qui arrivent a I'Air en passant par leur Poumons, in Me'moire^ de I'Aca- de'mie Eoyale des Sciences de Paris, for 1777, pub- lished in 1780. Lavoisier and La Place, Me'moire sur la Chaleur. Article IT. De la Combustion et de la Eespiration, in Me'm. de I'Acad, Eoy. des Sciences for 1780, published in 1784. Crawford, Experi- ments and Observations on Animal Heat, &c., Lon- don, 1788. Goodwyn, On the Connexion of Life with Eespiration, &c., London, 1788. Lavoisier and Seguin, Premier Memoire sur la Eespiration des Animaux, in Mem. de TAcad- Eoy. des Sciences for 1789 ; and Sur la Transpiration des Animaux, in Mem. de TAcad. Eoy. des Sciences for 1790. Men- zies. Tent. luaug. de Eespiratione, Edinburgh, 1790. Hassen fratz, Me'moire sur la Combinaison de I'Oxi- gene avec le Carbone et I'Hydrogene du Sang, sur la Dissolution de TOxigene dans le Sang, et sur la iNIaniere dont le Calorique se de'gage, in Aimales de Chimie, tom. ix. 1791. Coleman, On natural and suspended Eespiration, London, 1791. Vauquelitv, Observations Chimiques et Physiologiques sur la Eespiration des Insects et des Vers, in Annales de Chimie, tom. xii. 1792. Wells, Observations and Experiments on the Colour of the Blood, in Philos. Transact, of London for 1797. Sir Humphry Davy, Eesearches Chemical and Philosophical, See, Lon- don, 1800. Spallanzani, Me'moires sur la Eespira- tion, traduits par Senebier, Geneve, 1803. Bostock, On Eespiration, Liverj^ool, 1804. Henderson, Expe- riments and Observations on the Changes which the Air of the Atmosphere undergoes by Eespiration, particularly with regard to the^Absorption of Xitro- gen, in Xicholson's Journal of Xatural Philosophy, vol. vui. 1804. Brande, A concise Yiew of the Theory of Eespiration, in Xicholson's Journal, vol xi. 1805. Pfaff, Xew Experiments on the Eespi- ration of Atmospheric Air, &c., in Xicholson's Jour- nal, vol. xii. 1805. Lllis, On the Changes of At- mospheric Air in Eespiration and Vegetation, parts i. and ii. Edinburgh, 1807 — 1811. Allen and Pepys, On the Changes produced in Atmospheric Air and Oxygen by Eespiration, in Philos. Transact, of London' for 1808 : and. On Eespiration, in Philos. Trans, for 1809. BerthoUet, Sur les Changemens que ting the red corpuscles from the other constituents of the blood, and washing them in a solution of sul- phate of soda, fomid that they still changed from the venous to the arterial colour on the addition of oxy- gen. Dumas concludes, that neither the presence of albumen nor fibrin is necessarA- to enable oxygen to redden venous blood ; and Marchand, after a careful experimental investigation, affirms that the supposi- tion that the changes of colour in the blood are from a chemical action, is attended vdxh. insuperable diffi- culties (opus ciL Band xxxviii. S. 278). * Magnus and Marchand. RESPIRATION. 3G7 la Respiration produit dans I'Air, in Memoires de la Societe d'Arcueil, torn. ii. 1809. Prove7igal and Humboldt, Recherches sur la Respiration des Pois- sons, in Mem. de la Soc. d'Arcueil, torn. ii. 1809. Nysten, Recherches de Physiologic et de Chimie Pathologiques, Paris, 1811. Legallois, Experiences sur le Principe de la Vie, Paris, 1812 ; and Memoire sur la Chaleur Auimale, in Annales de Chimie et de Physique, torn. iv. p. 1, and p. 113. 1817. Dalton, On Respiration and Animal Heat, in Memoirs of the Literary and Philosophical Society of Manchester, second series, vol. ii. 1813. Prout, Obsei'\'-ations on the Quantity of Carbonic Acid Gas emitted from the Lungs during Respiration at different Times and under different Circumstances, in Thomson's Annals of Philosophy, vol. ii. 1813, and vol. iv. 1814. Nasse, Untersuchungen uber das Athmen, in Meckel's Archivfur Anatomie und Physiologic, Bandii. 1816. Coutanceau, Revision de Nouvelles Doctrines Chi- mico-Physiologiques, &c., Paiis, 1821. Dulong, De la Chaleur Animale, in Magendie's Journal de Phy- siologic, tom. iii. 1823. IF. T. Edwards, De I'ln- fluence des Agens Physiques sur la Vie, Paris, 1824. J)espretz, Recherches Experimcntales sur les Causes de la Chaleur Animale, in Annales de Chimie et de Physique, tom. xxvi. 1824; also in IMagendie's Journal, tom. iv. 1824. Scudamore, An Essay on the Blood, London, 1824. Herhst, Uebcr die Capa- citat der Lungen fur Luft in gesunden und kran- ken Zustande, in Meckel's Archiv, Band xiii. 1828. Collard de Martigny, Recherches Experimentales et Critiques sur I'Absorption et sur I'Exhalation Re- spiratoires, in Magendie's Journal de Physiologic, tom. X. p. 111. 1830; also, Recherches Experimen- tales sur I'Exhalation Gazeusc de la Peau, at p. 162 of the same volume. Apjohn, Experiments relative to the Carbonic Acid of the expired Air in Health and in Disease, in Dublin Hospital Reports, vol. v. 1830. G. R. and R. C. Treviranus, Versuche uber das Athmenholen der niedern Thiere, in Zeitschrift fur Physiologic, von Tiedemann und Treviranus, vierter Band. 1831. Christhori, On the Mutual Ac- tion of Blood and Atmospheric Air, in Edinburgh Med. and Surg. Journal, vol. xxxv. 1831. Stevens, Observations on the Healthy and Diseased States of the Blood, London, 1832 ; also. Observations on the Theory of Respiration, in London Medical Gazette, vol. xiv. 1834 ; and Philos. Trans, of London, vol. xlvi. 1835. Hoffman, Observations and Experi- ments on the Blood, in Medical Gazette for 1832, 1833, vol. xi. Reid-Clanny, Experiments on the Blood, in Lancet for 3d Nov. 1832, also on 13th April and 15th May, 1833. Gmelin, Tiedemann, and Mitscherlich, Versuche uber das Blut, in Zeitschrift fur Physiologic, Band v. 1833. Maach, De Rationc quas Colorem Sanguinis inter et Respirationis Fimc- tionem intcrcedit, Kiliae, 1834. Graham, On the Law of the Diffusion of Gases, in Trans, of Royal Society of Edinburgh, vol. xii. 1834 : On the Mo- tion of Gases, in Philos. Transact, of London for 1846. H. Nasse, Das Blut Physiologisch und Patho- logisch untersucht, Bonn, 1836 : also, article "Blut" in Wagner's Handworterbuch der Physiologic, 1845. Enschut, Disscrtatio Physiologico-Medica de Respi- rationis Chymismo. Trajecti ad Rhenum, 1836. Bischoff, Commentatio de Novis quibusdam Expe- limentis Chemico-Physiologicis ad illustrandam Doctrinam de Respiratione institutis. Heidelbergfe, 1837. 3Iagnus, Uebcr die in Blute enthalten Gase, Sauerstoff, Stichstoff, und Kolcnsaure, in Poggen- doi-ff's Annalen der Physik und Chemie, Band xl. 1837; Uebcr des Absorptions vermogcn des Blute fur Sauerstoff, in Poggendoi-ff's Annalen, Band lx^^. 1845. Maitland, Experimental Essay on the Blood, Edinburgh, 1837. Becquerel and Breschet, Re- cherches Experimentales Physico-Physiologiques sur la Temperature des Tissues et des Liquidcs Ani- maux, in Annales des Sciences XaturcUes, 2me serie, tom. vii. 1837. Dr. John Davy, An Account of some Experiments on the Blood in connexion with the Theory of Respiration, in Philos. Transact, of Lon- don for 1838 : Researches, Physiological and Ana- tomical, in 2 vols. London. 1839. Coathupe, Expe- riments upon the Products of Respiration at different Periods of the Day, in London, Edinburgh, and Dublin Philosophical Magazine, vol. xiv. 1839. McGregor, Experiments on Carbonic Acid thrown off from the Lungs, in p. 87 of Transactions of the Sections in the Report of the British Scientitic As • sociation for 1840. Leblanc, Recherches sur la Composition de I'Air confine, in Annales de Chim. et de Phys. tom. v. 1842. 3Iandl, INIemoire sur les Alterations qu'e'prouve le Sang pendant la Respira- tion, in Archiv. Gener. de Mod. 3me serie, tom. xiii. 1842. Beau and Maissiat, Recherches sur le INIe- chanisme des Mouvements Respiratoircs, in Archiv. Gener. de Medecine, 3me se'ric, tom. xv. 1842, and 4mc sex'ie, tom. i. ii. and iii. 1843. Bourgery, Memoire sur les Rapports de la Structure intime, avec la Ca- pacite fonctionelle des Poumons dans les deux Sexes, et a divers Ages, in Comptes Rendus, 23me Janvier, 1843, and in Archives Generales de Medecine, 4me serie, tom. i. 1843. Tlwmson, The Chemistry of Animal Bodies, Edinburgh, 1843. Valentin and Brunner, Uebcr das Verhaltniss der bei dem Athmen des Menschen ausgeschiedenen Kolensauere zu dem durch jenen Process aufgenommenen Sauerstoff, in Archiv fur physiologische Heilkmide, von Roser und Wunderlich, Band ii. 1843 ; also Valentin's Lehrbuch der Physiologic des Menschen, Band i. Braunschweig, 1844. Scharling, Versuche uber die Quantitat der, von cinem Menschen in 24 Stunden ausgeathmetcn, Kohlensaure, in Annalen der Chemie und Pharmacic von Wohler und Liebig, Band xiv. 1843. Fortgesctztc Untersuchungen zur Bestim- mung der Quantitat von Kolensaure, welche cin Mcnsch in 24 Stunden ausathmet, in Annalen der Chemie und Pharmacic, Band Ivii. 1846. Andral and Gavarret, Recherches sur la Quantite d'Acide Carbonique exhale par le Poumon dans I'Espece Humainc, in Annales de Chim. et de Phys. tom. viii. 1843. Malcolm, Some Experiments on the Propor- tion of Carbonic Acid formed during Respiration in Tyi^hus, in the London and Edinburgh IMonthly Medical Journal, 1843. Dumas, Essai de Statique Chimique des Etres Organises, 3mc edit. Paris, 1844. Enderlin, Physiologisch-Chcmischc Untersuchun- gen, in Annalen der Chemie und"Pharmacie, Band xlix. 1844. Boussingaidt, Analyses Comparees de I'Aliment consomme' et des Excrements rendus par une Tourtercllc, enti-cp rises pour rechcrcher s'il y a Exhalation d' Azote pendant la Respiration des Granivores, Ann. de Chim. et de Phys. tom. xi. 1844. Scherer, Uebcr die Farbc des Blutes, in Zeitschrift fiir rationellc Medizin, heraus-gegeben von Henle und Pfeufer, Band i. 1844. Bruch^ Uebcr die Farbe des Blutes, in Zeitschrift fiir rationellc Medizin, Band i. 1844. Xoch cinmal die Blutfarbe, in same journal. Band iii. 1845. Das Neuste zur Geschiclite der Blutfarbe, in same journal. Band v. 1846. Hidchinson, Contributions to Vital Statistics, &c., in Journal of the Statistical Society of London, vol. vii. 1844. On the Capacity of the Lungs, and on the Respiratory Functions, &c., in London Medico-Chirurgical Transactions, vol. xxix. 1846. 3Iarchand, Uebcr die Respiration der Frosche, in Journal fur praktische Chemie, von Erdman und Marchand, Band xxxiii. 1844. Uebcr die Einwir- kung des Sauerstoffes auf das Blut und seine Be- standthcilc, in same journal, band xxxv. 1845. Uebcr die Anwesenheit der kolensaurcn Salzc in dem Blute, in same journal, band xxxvii. 1846. Uebcr die Farbe des Blutes, in same journal. Band xxx^•iii. 1846. Gay-Lussac, Observations Critiques sur la Theorie des Phenomenes Chimiques de la Respiration, in Annales de Chim. ct de Phys. 3mc serie, tom. xi. 1844. Hannover, De Quantitate rclativa et absoluta Acidi Carbonici ab Hominc sano ct aegroto cxhalati, Hauniag, 1845. 3Iendelssohn, Der Mechanismus der Respiration und Cirkulation, Berhn, 1845. Vierordt, Physiologic des Athmens, Karlsruhe, 1845. Article " Respiration," in Wagner's Handworterbuch der Physiologic. In Sachen der Rcspirationslehre. Noch cine Antwort an Herr P. Lowenberg in Berlin, in 868 RODENTIA. Zeitschrift fur rationelle Medizin, Band v. 1846. Ludwig, Einige Bemerkungen zu Valentin's Lehren von Athmen und vom Blutkreislauf, in Zeitschrift fiir rationelle Medizin, Band iii. 1845. Renter, Be- leuchtung der Versuche von Prof. Scherer und Dr. Bruch uber die Farbe des Blutes, in Zeitschrift fiir rationelle Medizin, Band iii. 1845, Letellier, In- fluence des Temperatures extremes de I'Atmosphere sur la Production de I'Acide Carbonique dans la Re- spiration des Animaux a Sang chaud, in Comptes Rendus, tom. xx. 1845, and Annales de Chim. et de Phys. tom. xiii. 1845. 3Iulder, Zur Frage, auf welche Weise der SauerstofF der Luft bei der Respi- ration vom Blute aufgenommen wird, in Hollan- dische Beitrage zu den anatomischen und physiolo- gischen Wissenschaften, Band i. heft i. 1846. The Chemistry of Vegetable and Animal Physiology, translated from the Dutch by Dr. Fromberg, Edin- burgh, 1845. Liehig, Ueber die Abwesenheit der kohlensauren Alkalien im Blute, in Annalen der Chemie und Phamiacie, Band Ivii. 1846. Animal Chemistry, &c., edited by Dr. William Gregory, 3d edition, London, 1846. 3Ioleschott, Versuche zur Bestimmung des Wassergehalts der vom Menschen ausgeathmeten Luft, in HoUandische Beitrage, &c., Band i. heft 1. 1846. Stiow, On the Pathological Effects of Atmospheres vitiated by Carbonic Acid Gras, and by a Diminution of the due Proportion of Oxygen, in Edinburgh Med. and Surg. Journal, vol. Ixv. 1846. Fr. Nasse, Verbren- nung und Athmen, chemische Thatigkeit und or- ganisches Leben, Bonn, 1846. Loewenberg, Bericht uber die neuesten experimentellen Leistungen in Bezug auf den chemischen Process des Athmens, in Beitrage zur experimentellen Pathologic und Physiologic, heraus-gegeben von Dr. L. Traube, Berlin, 1846. Harless, Monographic uber den Ein- fluss der Gase auf die Fonn der Blutkorperchen von Rana temporaria, Erlangen, 1846. Sibson, On the Mechanism of Respiration, London Phil. Transact, for 1846. Lehmann, Ueber den Gehalt des Blutes an kolensauren Alkali, in Journal fur praktische Chemie, band xl. 1847. (John ReicL) gnawing. The molar teeth have their crowns flattened and traveised by plates of enamel, arranged transversely, the better to antagonise the backward and forward movement of the jaws. Fis- 2i7. RODENTIA (G/ir^-^, Linn.) (Fr. Rongeurs). — An important order of mammiferous Verte- brata, distinguishable by the remarkable struc- ture of their incisor teeth, which are adapted to perform the ofEice of chisels by cutting and gnawing away the hard vegetable substances, which form their principal food. The animals of this order, indeed, appear to be specially ap- pointed to devour the hardest substances, ge- nerally living upon the wood and bark of trees, as well as upon nuts and other shelled fruits. The incisor teeth, which characterize the ani- mals of this order, are situated in both jaws, and are separated from the molar by a considerable space, so that they are ill-adapted to seize living prey, or to devour flesh, notwithstanding that certain genera of rodents exhibit decidedly carnivorous propensities. These incisors, also called denies sca/praini, are only provided with enamel upon their anterior surface, so that the posterior portion of the tooth being worn away more rapidly than the an- terior, these teeth always present a chisel-like edge. The lower jaw is articulated to the cranium by a longitudinal condyle, in such a manner that it has no horizonal motion ex- cept from before, backward, and vice versa; a movement adapted to effect the act of Pteromys volitans. Those genera in which these layers of enamel are simple plates, and which have the crowns of their molar teeth very flat, are more particularly frugivorous ; those in which the eminences of these teeth are divided into blunt tubercles, are omnivorous ; whilst a small number of genera, which possess pointed mo- lars, will attack other animals, and in some of their habits approximate the Carnivora. This order comprises the following genera : — Sciurus (Squirrel). Pteromys (Flying Squiriel) (j%. 247,). Cheiromys (Aye-Aye). Arctomys (Marmot). Myoxus (Dormouse). Echimys. Hydromys. Capromys. Mus(Rat). Gerbillus. Meriones. Cricetus (Hamster). Arvicola (Vole). Fiber (Musk Rat). Geo- rychus (Lemming). Otomys. Dipus (Jer- boa) {Jig. 248.). Poephagomys. Helamys. Spalax ("Rat Mole) {fg, 249.) Bathiergus (Cape Mole) (/g. 250.). Geomys. Diplo- stoma. Castor (Beaver). Myopotamus (Coui). Hystrix (Porcupine). Lepus (Hare). Lago- mys (Rat Hare). Hydrochcerus (Capybara). Rhyzomys. Cavia (Guinea F'ig). Dasyprocta (Agouti). Ccelogenys (Paca). Chinchilla. RODENTIA. Fig. 248. 369 Dipus hersipes. Bones of the cranium. — The bones of the mina are united into one, in front of which cranium in the Rodentia present several pecu- the sphenoid forms a single vertical lamella, Fig. 249. Fig. 251. Spulax typlUus. Skull of the Hare. liarities in their arrangement, which it will be an evident approximation to what is found in necessary to notice. birds. Fig. 2.50. Batliiefgus mca iiim us. In the hare*, the anterior sphenoid is very The os frontis presents a stronj? supra- remarkable, inasmuch as the two opiic fora- orbital crest, which is deeply notch'ed both * Cuvier, Anatomic comparee, last edition. before and behind. It advances on e:irh side VOL. IV. 370 RODENTIA. by a long process, between the ascending point of the inter-maxillary bone and that portion of the maxillary which forms the cheek : the parietals remain for some time distinct from each other, and from the inter-parietal ; which latter, in the rabbit, is small, and resembles an ellipse placed transversely : in the hare this last bone can only be detected in very young specimens, when it is found to con- sist of two small pieces, which are separated by a prominent angle of the occipital. The petrous portion of the temporal bone occu- pies a large triangular space in the occipital region of the skull. The mastoid process is entirely formed by the occipital bone; but the ospetrosum furnishes a parallel process, which embraces the temporal externally, and at an early period it becomes united therewith. The t3'mpanic portion of the temporal is con- siderably arched, but is far from reaching the pterygoid processes. The temporal alae of the posterior sphenoid do not mount up very high, and do not reach the frontal, from which they are separated by the anterior sphenoid and by the temporal, still less do they ap- proximate the parietal bones, which do not descend so low as the temporal. In the marmot, the frontal and the parietal bones are at a very early age consolidated into a single piece, and an inter-parietal bone is not discoverable even in very young mar- mots. The frontal bones, which are extensively penetrated by the two ossa nasi, penetrate deeply between the parietals, which latter are narrow, and the sutures which connect them to the temporal remarkably straight and pa- rallel. The occipital suture is situated a little in front of the occipital crest, with which it runs nearly parallel. One-third of each side of this crest is formed by the petrous bone, which infringes slightly upon the occipital surface of the cranium. External to the tympanum, and a little behind it, there is a mastoid process ; behind which is another (the paramastoid), formed by the oc- cipital bone. The tympanic bones are round and much inflated ; they are consolidated at an early age with the petrous bones. In the temple the posterior sphenoid mounts consi- derably upwards, but nevertheless only joins the temporal and the frontal, the parietal not descending sufficiently low. The orbital ala of the sphenoid enters but little into the com- position of the orbit. In the squirrel the separation between the parietals and the frontal bones is likewise obliter- ated at a very early period. The inter-parietal also becomes soon confounded with the parietal ; but in very young subjects its presence is well- marked ; it is of semi-circular form. There is, moreover, a special point of ossification in the centre of the cross, formed by the frontal and parietal bones. The glenoid cavity is more deeply excavated than in the marmot. In the beaver, the frontals are consohdated together at a very early age ; the parietals also unite to each other and to the frontals, even before the inter-parietal has become blended with them. The inter-parietal is triangular, and in very young subjects is double. The glenoid cavity is bioader than it is long ; its external border only is formed by the jugal bone ; its posterior margin is al- together free. The tympanum is altogether formed by the tympanic bone. Between the two tympana the basilar region . of the cranium is hollowed to such an extent as to be partly membranous, even in very old animals. There are two mastoid tubercles placed near to each other ; one formed by the petrous bone, the other by the occipital. The petrous bone becomes united at an early period to the tympanic bone, a pointed apophysis of the temporal insinuating itself between them, behind the external auditory foramen. The posterior sphenoid joins to the frontal in the temporal region ; the anterior sphenoid then mounts up very high ; and in adult spe- cimens, when the molar teeth have come down, and the maxillary bones are no longer distended, there is inferiorly a compressed portion, by which the sphenoid joins the maxillary and the palatine bones, and which forms a partition pierced with several holes between the bottom of the two orbits. In the Cape mole (Batliiergus) the sutures at the upper part of the cranium are disposed much in the same way as in the beaver, only in the larger species the temporals are broader anteriorly, and encroach upon the frontal in front of the parietal. The inter-parietal is of an oval shape. The temporal presents, posterior to its arch, a large fissure, which is not closed by the os petrosum : the latter bone, however, on the other hand, fills up a dee[) notch, which exists on the external border of the occipital bone. The paramastoid apophysis is dilated into a prominent plate. Fig. 252. Skull of the Bathkrgus maritlmus. The anterior sphenoid, which enters but little into the composition of the orbit, forms beneath it a simple lamella, but which is not perforated. The posterior sphenoid does not ascend into the temporal, but a considerable prolongation of the frontal bone comes down to unite with it, about the level of the edge of the glenoid cavity ; it also furnished a process to be articulated both with the pala- tine and the maxillary bones. In the ondatra and the ivater voles the parietal bones are, as it were, imbedded in the shape of a disk between the temporals. The temporal, moreover, furnishes a prominent projection, that might be mistaken for the RODENTIA. 371 post-orbital apophysis of the frontal, which latter does not exist. The frontal bones, Fig. 253. Skull of the Ondatra. which are consolidated together long before the parietal, are much reduced in size, in con- sequence of the extension of the temporals, and the narrowness of the inter-orbital space. The inter-parietal remains for a long time distinct, it is very large, and is situated be- tween the two parietals, the two temporals, and the sphenoid. The posterior sphenoid mounts much higher into the temporal region than in the genus Bathiergus, and joins both the tem- poral and the frontal. The parietal does not reach within a considerable distance of it. The tympanum is prominent, and reyts posteriorly upon a well-marked paramas- toid process. The suture between the tympanic and the petrous bone exists till a late period. The occipital portion of the petrous bone forms no tubercle, but pene- trates deeply into the occipital. In the rats, properly so called, the frontals which remain separate for a long period, are distinguished from the parietal by the inter- vention of a straight transverse line. Their inter- parietal is rectangular and placed trans- versely, but does not reach as far as the temporal bones. The posterior sphenoid does not mount into the temporal region to a greater height than the anterior; it there joins the frontal, but remains separated by a con- siderable space from the parietal. In the gerbilles the fronto-parietal suture forms the arc of a circle. The inter-parietal is broad transversely ; its suture with the parietals is nearly straight, and it is embraced posteriorly and laterally by the occipital. The temporal, upon the sides of the cranium, is comparatively small in front ; it touches the frontal at the extremity of the frontop-arietal suture ; posteriorly it continues the suture, which, descending from the inter-parietal angle, separates the parietal from the occipital : the latter bone is deeply notched to receive the os petrosum, which it separates from the inter- parietal by a quadrilateral process. The ar- rangement of the bones in the orbit resembles that of the genus Miis. The tympana are extremely vesicular and prominent ; they bound posteriorly the glenoid cavity, which resembles a deep furrow. There are small paramastoid apophyses closely applied to them. In the hamster (Cricehts) the inter-parieta is a small tri angular bone ; the temporal is extended at the expense of the parietal, and stretches as far back as the occipital. The orbital and temporal alae of the sphenoid are arranged in the orbit as in the rats. There is no paramastoid process behind the condyles of the lower jaw. The same observations are applicable to the dormice, but their inter-parietal bone is elongated transversely, so as to touch both the occipital, the parietal,' and the temporal ; the posterior sphenoid, moreover, only touches the maxillary by its apex. A little process, derived from the palatine, separates them below. These animals have the zygomatic arch situated lower down and broader than the hamsters. Their tympana are much larger, well rounded, and in contact with the inter- nal pterygoid processes. Fig. 254. Skull of the Spalax typhlus. In the rat ynoles (^Spalax) the occipita bone is flanked by the ossa petrosa and the temporals, to form the occipital surface of the cranium ; but the occipital suture is as usual situated in front of the occipital crest — a circumstance which encroaches much upon the parietal bones. This disposition is in relation with the strength of the muscles that support the head. The parietal encroach upon the frontal by a pointed process. The temporal ridges unite together to form a single sagittal crest, and the zygomatic arches are very prominent, externally corresponding to the great size of the temporal muscles. There is no inter-parietal bone. The tympana are but slightly arched. In the rhyzomys of Sumatra, on the con- trary, it is the frontal which extends by a pointed process between the parietal ; and, moreover, the temporal bones mount upwards very high upon the cranium, so as to join the frontal; there is no inter-parietal bone visible. The OS petrosum is visible upon the occipital aspect of the cranium. A process derived from the temporal, which contributes to form the occipital ridge, is interposed between the OS petrosum and the external auditory tube. The tympanum is lofty and well-rounded, and separated from the petrous bone behind by a process of the occipital, which terminates in a paramastoid tubercle. In the jerboas (Dipus, Gmel.), the lines of separation between the frontal and parietal B B 2 372 RODENTIA. bones form a perfect cross; the inter-parietal bone is large and of a rhomboidal shape. In the alactaga {Mus jacuhis, Lin.), a spe- cies of the same genus, the inter-parietal is Fig. 255. Skull of the Dipus Jiersipes. separated from the temporal by a broad pro- cess divided from the occipital, which runs to join the parietal, as in the gerbilles (Ger- hillus, Desmar, Meriones, Ilig). The os petro- sum occupies a considerable space in the occipital region ; but in the jerboa the great development of the ear renders impor- tant changes in the structure of this portion of the skull indispensable. All the hinder por- tion of the temporal bone is reduced to a thin osseous band, which is closely connected with the dilated tympanum and with the os petro- sum, surrounding entirely the auditory canal. Another narrow band is derived from the sum- mit of tile occipital bone, which runs to be- come united at a right angle with the above process derived from the temporal, so that a small triangular space is formed between the parietal, the occipital, and the temporal, in which is visible, at the upper part of the skull, that great vesicular mass, which occupies a part of its base and its posterior aspect. The paramastoid apophysis is a little tubercle which leans against the t^ mpanum, and bounds posteriorly the articulating surface of the lower jaw. In the helamys (Cape jerboa, or jumping hare), the structure of the skull in the vi- cinity of the ear is analogous to that of Dipus. The petrous bones arise to the upper part of the cranium, and there oc- cupy a considerable space between the tem- poral and the inter-parietal bones, so that the temporals only give off a narrow band posteriorly, which does not reach the occipital bone, and does not surround the auditory passage, as in the jerboa. From the absence of any slip derived from the occipital bone, the upper portion of the os petrosum is not divided into two parts, as it is in the jerboa. The tympanum also is much less developed, and in its vicinity there is a very distinct paramastoid process. The inter-parietal, which is triangu- lar, moreover, touches the parietals, the ossa petrosa, and the occipital. The lines of sepa- ration between the frontals and the parietals form a cross ; the former are much larger than the latter. The anterior sphenoid is perfo- rated at the bottom of the orbit. The tem- poral aljE do not ascend higher than the orbital, and remain widely separated from the parietal. In the ec/iivij/s (or porcupine rat of Az- zara), the line which separates the frontal from the parietal bones is straight. The inter- parietal is obliterated at an early age. A very distinctive character peculiar to the echimys is, that the occipital bone, as it descends late- rally towards the ear, bifurcates in such a way as to enclose the ascending portions of the tympanic bone and of the os petrosum, form- ing by itself both the mastoid tubercles instead of the posterior one onl}^ as is usually the case. The anterior sphenoid gives off an orbital plate, which is moderately elongated ; but the posterior is almost excluded, both from the temporal region and from the orbit, owing to the length of the temporal front of the suture in this part. It is hardly visible except at the base of the cranium. The articulating surface for the lower jaw is of a transverse form with- out any marginal boundary behind. In the cojjromys the bifurcation of the oc- cipital bone is equally distinct, but its two processes join inferiorly in such a way, that only a small hole is left occupied by the os pe- trosum. The orbital wing of the sphenoid is also less extensive. In the porcupines the frontal bones are very wide in front between the lachrymals. In young animals, a large semi-oval inter-parietal is met with ; but this bone, as w^ell as the pa- rietals and the frontals, unite at a very early period into one piece ; they also at an early age become consolidated with the ossa nasi, so that these seven bones not only form one piece, but even become united to the tempo- rals and to the occipital long before the bones of the face are anchylosed with each other. The OS petrosum is scarcely discoverable at the back of the cranium, where it only forms a small tubercle embraced by two processes of the occipital, the interior of which represents the mastoid process of the temporal bone, and forms, external to the condyles of the lower jaw, a broad paramastoid apophysis. The pos- terior sphenoid does not reach so far as the orbit, or rise above the anterior, which latter is but slightly visible upon the exterior of the skull. In the coendou the parietal bones are pro- longed by a pointed process between the frontals ; the suture between them, and also between the inter-parietal and occipital, is ob- literated. The tympanum is much arched ; the OS petrosum hardly appears in the occipital region of the skull, but is slightly visible a little behind the tympanum above the paramastoid apophysis, which is of moderate size. In the paca the frontal bones are much elongated ; the suture between them and the parietals is transverse ; the temporal extends backwards as far as the occipital ridge, and descends behind the tympanum over the base of the mastoid process, the point of which be- longs to the occipital bone. The relations of the sphenoid orbital plates are as in the agouti, but the tympana are less prominent. In the foetus, and in very young subjects, there are two parietal and two inter-parietal bones ; but these four pieces become at an early age consolidated into one. In the Guinea-pig (Cavio) the parietal RODENTIA. 373 bones and the inter-parietal, whicli is large, and of a semi-oval shape, are at an early period consolidated into one piece. The occipital bone extends beyond the occipital crest in the upper region of the skull, but the sides are formed by the temporal. The petrous bone, which is in early age consolidated with the tympanic, is slightly visible by a narrow slip in the occipital region. The tympana are much arched, but the pterygoid processes do not touch them, because the foraynen lacerum anteiius, which is very large, separates them. The superior maxillary bone is articulated posteriorly with the pos- terior sphenoid above the palatine, upon the occipital region of the cranium. In the couia (Mi/opotamus, Commerson) the sutures between the frontal and parietal bones form a complete cross. The inter-parietal is united to the surrounding bones at an early age, but in young individuals it is very large, and divided into two pieces ; in the adult ani- mal the zygomatic processes of the temporal bone formed at their extremities a strong hooked process, which winds down beneath the jugal bone. The posterior sphenoid does not enter into the composition of the orbit ; the OS petrosum is visible externally in the occipital region of the skull, situated between the two mastoid processes, which are both formed by the occipital bone, but are of very unequal length ; the external is pointed, the inferior and internal is of much greater size, running backwards and outwards, compressed, pointed, and recurved. In the agouti, the frontal and nasal bones remain separate, although the parietal and in- ter-parietal are united into one piece ; in young subjects the inter-parietal is of great size, and semicircular in its shape. The or- bital plate of the sphenoid enters largely into the composition of the orbit, where it articu- lates by it posteriorly with the temporal. In the preceding genera it is to be remarked, that the posterior sphenoid is joined to the frontal, which is interposed between the temporal and the orbital alae of the sphenoid; the tympana regularly arched. The os petrosum does not appear externally, but in addition there here re-appears a small portion of the ethmoid, in- terposed between the orbital ala of the sphe- noid, the frontal and the lachrymal bones. In the capyhara the hinder portion of the cranium, as well as the occipital bone and the inferior region of the temple, resemble what is met with in the kerodon of Patagonia. The paramastoid apophysis is excessively long, the tympana are small. The petrous bone does not appear at all in the occipital region of the cranium. The parietals and inter-parietals are consolidated into one piece at a very early age, and separate, by a process more acute than in any of the preceding genera, the cra- nial portion of the temporal bone into two branches ; the frontals are likewise united together in very young animals. In the viscache the squamous portion of the temporal bone is likewise deeply indented by a point derived from the parietal. The posterior branch of this bifurcation, which is narrow at its commencement, enlarges as it approaches the occipital ridge. The inter-parietal and the parietals are united into one piece, the frontals are distinct, and the coronal suture is transverse. The zygomatic process of the temporal is directed almost horizontally, and this bone remains widely separate from the maxillary ; the posterior sphenoid unites with this latter bone, external to the palatine, which does not penetrate into the temple or into the orbit : the posterior sphenoid has no temporal ala, so that it reaches neither the frontal nor the parietal bone — a circumstance which has been already remarked in preceding genera. In ihekerodons, the frontal bones remain se- parate after the parietal and inter-parietal are conjoined. The fronto-parietal suture is trans- verse. The superior margin of the occipital is bent upon itself at a right angle, as in the hares, and articulates at the side of the cranium with the temporals, terminating laterally by a long, slender, vertical, paramastoid process. The temporal gives off posteriorly a lamina, or apophysis, which descends more or less in different species between the tympanum and the petrous bone. The latter bone is not visible externally in the occipital region, but is apparent upon the side of the head, above and behind the auditory passage. The con- nections of the bones in the orbit are not less remarkable than in the Guinea-pig. The tem- poral is in like manner developed at the ex- pense of the posterior sphenoid ; but it is the former which becomes united by its apex to the extremity of the maxillary bone, the sphenoid which runs parallel with it only ap- proaching the maxillary, from which it is separated by a slip derived from the os palati. The temporal, as in the preceding genera, is united in the orbit to the anterior wing of the sphenoid in the Guinea-pig, with this differ- ence, however, that the temporal leaves it free externally. The petrous bone occupies a considerable surface in the occipital region of the skull, and likewise furnishes a mastoid tubercle at the base of the paramastoid apophysis, which resembles that of the couia ; and which, at first, running outwards and backwards, suddenly bends inwards and for- wards. The petrous bone occupies a large part of the occipital region, where it presents a flattened surface ; it also furnishes a mastoid tubercle at the base of the paramastoid apophysis, which resembles that of the couia, and which, at first, directed outwards and backwards, afterwards suddenly bends in- wards and forwards. In the chinchilla the connection of the frontal and of the parietal bones, as well as those of the sphenoid with the maxillary and with the temporal, are the same as in the viscache, but the great development of the ear causes differences in the posterior region. The paramastoid apophysis, which is strongly marked, is closely applied against the tympa- num, and does not project inferiorly. The petrous bone, instead of presenting a flat sur- B B 3 374 RODENTIA. face in the occipital region of the skull, is ex- tremely dilated, insomuch, indeed, that this dilatation appears in the upper wall of the skull, in the shape of two large projections, bounded in front by the parietals, internally by a plate common to them and the occipital bone, and posteriorly by a long narrow trans- verse projection from the occipital, which is in contact with the petrous bone, and exter- nally by another thin and pointed slip, which forms the posterior termination of the tempo- ral bone, and which projects above the audi- tory meatus to join that derived from the occipital. We have seen, above, that in the jerboa a similar disposition exists. Bones of the face. — In the Rodentia the intermaxillary bones are of enormous dimen- sions, on account of the great size of the inci- sor teeth, so that the maxillary bones are pushed very far backwards ; these latter form a large portion of the inner wall of the orbit, into the composition of which the os palati enters but slightly, and sometimes, indeed, not at all. The anterior boundary of the orbit is formed by a process of the maxillary bone, which proceeds to contribute to the formation of the zygomatic arch in such a way that the os malae is, as it were, suspended in the centre of the arch between the apophy- sis, derived from the maxillary and the zygo- matic process of the temporal bone.* It joins neither the frontal nor the sphenoid. The elongation of the ossa nasi is such that the opening of the nose is situated quite at the extremity of the snout. In the aye-aye the bones of the nose are short and broad. The intermaxillaries mount up along their sides by a broad process, which occupies part of the snout, and are articulated to the frontal by a tolerably broad space ; they touch, likewise, the lachrymals v/hich encroach upon the cheek ; while the canal situated between the latter bones, the maxil- lary, and the jugal, is out of the orbit. The jugal apophysis of the maxillary arises oppo- site the second molar tooth, and the boundary of the Jugal bone is placed at the anterior base of the zj'gomatic arch. It articulates with the lachrymal, both within and without. The orbit is very broad, and furnishes a large post- orbital apophysis, which joins that derived from the frontal bone. The palatine bone advances but a little way into the palate, ter- minating by a straight suture between the last molar teeth. The palatine portion of the pterygoid alae is simple ; their sphenoidal portion is divided into two laminte, the ex- ternal of which is prolonged as far as the t} mpanum, to which it is articulated, as well as to the inner border of the glenoid surface. In the temporal region, the palatine bone re- mains behind the posterior margin of the maxillary, between the latter bone and the two sphenoids, only touching the frontal by its apex. In the hares, the intermaxillary bone pre- * It will be seen from the details that follow, that the part played by the os mahB in the construction of the cheek is not always so simple. sents, besides its palatine portion, which is large, a long ascending apophysis, which is at first imbedded between the maxillary and the OS nasi, and subsequently between the latter and the apophysis of the frontal, to which latter it is connected. All that portion of the maxillary bone which forms the cheek is, in the adult animal, riddled with holes, so as to have the appearance of lace-work. The la- chrymal in the orbit is tolerably large ; exter- nally, it gives off a blunt hook, beneath which is the lachrymal canal, situated upon the very edge of the orbit. The zygomatic portion of the maxillary bone is short ; its inferior margin forms a ridge, which projects slightly externally, and presents a flattened surface, from which arises one of the portions of the masseter muscles. It is this surface which we shall see in other -Rodentia become rounded into a more or less oblique vaulted space, and in others become transformed into a wide ring. The union between the maxil- lary and the jugal bones is so soon obliterated, that unless we examine very young indivi- duals we should be tempted to believe that no jugal existed. This latter bone is arched in- feriorly, and extends by means of a process beneath the zygomatic portion of the temporal bone. Besides the floor with which it covers the roots of the teeth, the maxillary gives off a narrow plate, which mounts into the orbit as high as the os frontis, between the lachry- mal, from which, however, it is separated by a membranous space and the anterior sphenoid. The vomer is visible at the hinder part of the septum, which separates the foramina inci- siva. The palatine occupies beneath the an- terior sphenoid in the orbit a much greater space than in other Rodents ; inferiorly it extends as far as the third molar tooth, and is deeply indented as far as the fourth. The ptery- goid alae extend to the azygos portion, or to the body of the anterior sphenoid, but they are separated from that of the posterior sphenoid by a membranous space on each side. The posterior sphenoid has on each side two pterygoid plates, which are both of them con- tiguous to those of the palate bones ; the in- ternal ones terminate in a slender point or style. In the lagomys, the base of the zygomatic arch gives off a process, which is directed downwards ; and the jugal bone, after having passed beyond the zygomatic process of the temporal, is prolonged directly backwards into a lengthened point. In the marmot, the two nasal bones con- stitute the middle of the upper vault of the snout. On each side of them the ascending apophysis of the intermaxillary bones, which are broader than in the hares, run up to be articulated with the frontal, the anterior border of which is transverse and only slightly festooned. The external surface of the maxillary is concave beneath a ridge, which is continuous with that of the zygomatic arch, extending as far as the intermaxillary suture. Setting off from this point, the intermaxillary suture descends vertically to embrace the RODENTIA. 375 palate, of which it occupies rather less than a third. The jugal bone reaches to the anterior base of the zygomatic arch, where it articulates with the lachrymal as well as with the maxil- lary bone ; it is connected with the zygomatic apophysis of the os temporis by a horizontal suture, which occupies all the second half of the arch, so that it extends as far back as the glenoid cavity, the external margin of which it fills. The lachrymal is of moderate extent in the orbit, but is scarcely visible beyond the margin of that cavity ; besides its canal, which is altogether within the orbit, there is a small unossified space between it and the maxillary bone, situated very near to the pos- terior opening of the sub-orbital canal. The large space occupied by the maxillary in the orbit keeps the lachrymal widely sepa- rated from the palatine bone, with which it articulates so extensively in the Carnivora. The palatine bone occupies, posteriori}', about one-fifth of the extent of the palate. After having formed the root of the pterygoid alae, it is prolonged between them for about half their length laterally ; it mounts up into the temporal region as high as just beneath the optic foramen ; it there spreads out back- wards as far as the spheno-orbital foramen, and forwards, as the foramen which represents the spheno-palatine. The internal pterygoid process is not detached from the sphenoid, and terminates posteriorly in a long hook. The external pterygoid plate is very distinct ; although but little prominent, it covers the vidian foramen, and touches with its point the extremity of the maxillary. In the squirrel, the lachrymal hook is formed by the bone of that name ; but it is also doubled by a similar unciform process, derived from the jugal. There is no membranous space between the lachrymal and the maxillary. The prolongations of the palatine bone be- tween the pterygoid alae are shorter. In other respects the relations of the bones to each other are very similar to what exists in the marmot. Fig, 256. Skull of the Beaver (^Castor Fiber). In the heaver^ the post-orbital apophysis of the OS malae is very large and blunt, and all this portion of the bone very broad ; it occu- pies the greater portion of the zygomatic arch. The two nasal bones are broader in their middle, and both the intermaxillary and max- illary bones reach up as far as the frontals. The lachrymals are small, especially that por- tion of them which is situated without the orbit, to which the jugal bones touch. The vaulted portion of the maxillary bone is very extensive and well circumscribed in adult ani- mals ; on its external margin, by the ridge, which is continuous with the inferior edge of the zygomatic arch, and internally by another ridge, which commences close to the sub- orbital foramen, and mounts up on the cheek to join the ridge last mentioned. The pala- tine bone occupies in the palate a triangular space, extending as far forward as opposite the second molar tooth; it terminates pos- teriorly between the two pterygoid alae. The external pterygoid apophysis is of moderate length, nearly rectangular in its shape, and is pierced at its base by the vidian canal ; it ar- ticulates broadly with the posterior part of the maxillary in such a way as to exclude the palatine both from the orbit and from the temple. The internal pterygoid apophysis is of a hooked form, the point of the hook reaching as far as the tympanum. In the orycteres, the jugal bone com- mences at about the anterior fourth of the length of the zygomatic arch, and conse- quently remains widely separated from the lachrymal. The ossa nasi constitute scarcely half the breadth of the snout, in which the maxillary occupies much less space, it being here the inter-maxillary which principally forms it. The last-mentioned bones mount up upon the forehead higher than the bones of the nose — a circumstance which is the reverse of what occurs in the beaver. The concavity of the maxillary beneath the base of the zygomatic arch is reduced to a slight oval depression; but its zygomatic apophysis is very long ; it is the maxillary bone and the frontal, to which it is joined by a long suture, which forms almost alone the osseous walls of the orbit. There is no lachrymal suture visible, although the lachrymal canal is distinctenough. The external pterygoid apophysis presents neither crest nor prominent angle ; the inter- nal resembles that of the beaver. In the ondatra and the ivater voles, the bones of the nose, which are pointed at their summits, are considerably enlarged at their inferior extremities. The intermaxillaries occupy a smaller portion of the snout than the preceding pieces, the oblique excavation at the root of the zygomatic arch exists ; but it is separated from the cheek superiorly by the vertical prolongation of the sub- orbital fora- men. The malar apophysis of the maxillary extends beneath the jugal until it almost reaches that of the temporal ; so that the jugal is only free at its lower margin for a very small space, and is very far removed from the lachrymal, which latter bone does not appear external to the orbit, it being concealed in the sub-orbital canal. The os palati extends into the palate as far as the first molar tooth, but is not visible either in the orbit or in the temple, in which latter region the maxillary is connected to the two sphenoids and to the B B 4; 376 RODENTIA. frontal, as far as the lachrymal. The two pterygoid alae are well developed and of equal size ; the internal are connected with the tympanic bones, as are the external ; and by their anterior margins the latter are connected with the maxillary to a greater extent than in the beaver, so that no part of the palatine is visible externall}-. In the rats, properly so called, the bones of the nose likewise increase in breadth, towards their extremity, to an extent which varies in different species. The intermaxillaries are joined to the frontal by a suture con- sisting of extremely fine and numerous in- dentations : they form scarcely the half of the snout, comprehending the vault and the roof of the zygomatic arch, which is here directed much further outwards, and is separated from the rest of the cheek by a deep groove ; in front of this groove the maxillary is ex- cavated into a sort of pouch, its zygomatic process is very long, the jugal bone short and slender. The lachrymal is entirely contained within the orbit, no part of it being N-isibk at the point of union between the frontal and maxillary upon the margin of the orbit, but a prominent hook-process, situated within the edge of the orbital cavity. The palatine fills up half the space situated between the fora- mina incisiva and the hinder margin of the palate ; its pterygoid wings, moreover, are con- siderably prolonged between those of the sphe- noid, but the external pterygoid alae of the latter bone entirely cover it externally by passing to join the maxillary, as in the ondatra, never- theless it shows itself in the floor of the orbit embraced in a fissure of the maxillary bone. The points of the internal pterygoid apophyses do not reach as far as the tympanum. There is be- tween the pterygoid alae a membranous space. In the gerbil/es, the bones of the nose and the intermaxillaries are prolonged in front, a little beyond the incisor teeth ; the suture be- tween the intermaxillary is composed of radi- ated indentations; the maxillary bone expands into a very thin lamina at the anterior margin of the orbit ; and this lamina is continuous with another given off at this point i)y the lachrymal ; the jugal bone is very slender ; the palatine runs forward in the palate as far as the middle of the first molar tooth ; posteriorly it is not visible in the orbit, the articulation of the external wing of the sphenoid with the maxillary conceahng it on the outer side, as in the preceding genera. The internal pte- rygoid apophysis reaches as far as the tym- panum. In the hamsters, the bones of the face closely resemble in their disposition those of the rats properly so called. In the dormice (Mi/oxiis), as in the gerbilles, the end of the snout projects beyond the incisor teeth ; and the intermaxillary bone occupies a large portion of the snout ; whence it results that it is pro- longed upwards by a short ascending branch. In Myoxus nitela the maxillary presents be- neath the sub-orbital hole a prominent tubercle, which does not exist in the dormouse {Mi/oxus Glis). Both of them have a mem- branous space in each of their palatine bones ; and, moreover, this bone retakes its usual position between the maxillary and the sphe- noid upon the outer side of the pterygoid ala, so that the latter is only in contact with the maxillary by its apex, nearly in the same manner as in orycterus. In spa/ax (the rat mole), the bones of the nose become at an early period consolidated together for a portion of their length, they expand infeiiorly, and are proportionally of larger size than in orycteres. The process of the maxillary which surrounds the infra-or- bital hole is broad and thin ; the jugal is very slender, and does not at all contribute to form the inferior rim of the orbit ; the ex- ternal pterygoid apophysis almost covers the foramen ovale. In the rhizomys of Sumatra, the fronto- maxillary suture continues the line of union between the frontal bone and the other bones of the face. The bones of the nose are sepa- rate, and the frontals consolidated together : the bones of the nose are here of a triangular form. The lachrymal is entirely contained in the orbit; the jugal, which is broad, occupies the centre of the zygomatic arch ; the palatine is small, and of a triangular shape in the re- gion of the palate ; it is not visible in the orbit, on account of the union between the ala of the sphenoid and the maxillary bone, which is as extensive as in the ondatra. The in- ternal pterygoid apophysis is prolonged into a long hook. In the jerboa, properly so called, and in the alactaga, the jugal ascends at a right angle along the posterior edge of the great pre-orbital ring as far as the lachrymal, with which it is connected. In the jerboa this part is enlarged into a broad lamina ; in the alactaga it is a simple, stem-like process. The maxillary takes beneath the sub-orbital hole the form of a large ring, which might almost be mistaken for an orbit. The lachrymal forms towards the upper part of this ring a broad hood-like process. The bones of the nose cover the whole upper part of the snout, and are even bent a httle into a tubular form at their extremity. The ascending ramus of the intermaxillary is very narrow at its origin, between the nasal and the maxillary ; it after- wards spreads out as it approaches the frontal, with which it is connected on a level with the bones of the nose by a finely serrated suture. In the pcEp/iagomi/s the jugal is broad, it gives oflp a post-orbital apophysis, and does not mount along the pre-orbital ring. The face of this animal offers a very remarkable peculiarity. A cylindrical tube, bent into an arched shape, traverses the great ring, and is applied beneath the orbit against the alveolar arch. In this genus, as in the preceding, the maxillary is connected with the sphenoid. In the helami/s the jugal is broader, and extends along a little more than half of the ring ; the rest is completed by the lachrymal, and even by the frontal bone. The lachrymal in this genus has no hook-like process : after having shown itself external to the orbital RODENTIA. 377 ring, it occupies a considerable space in the orbital cavity ; but the entrance of the lachrymal canal is concealed by the sub-orbital arch. The bones of the nose are singularly robust ; the ascending ramus of the intermaxillary is, on the contrary, very narrow, even at the point where it joins the frontal. The pre- orbital ring is of large size, and the malar apophysis of the maxillary arises close to the intermaxillary suture. A few lines behind the incisor teeth the palatine interposes itself, under the shape of a round shield-like plate, between the sphenoid and the maxillary. In the echimys the jugal is very long, and tolerably broad ; the lachrymal is small, and is furnished with a little hook-like process ; the maxillary presents, inferiorly, in front of the molar teeth, a small fossa and a malar apo- physis, the margin of which is broad and flattened. The bony arch of the pre-orbital ring is simple, and not doubled posteriorly by an ascending apophysis of thejugal, as is the case in the jerboa ; or by the latter and the lachry- mal, as in the helamys and the viscache. The palatine is deeply indented posteriorly, but it ascends into the orbit, and likewise appears in the pterygoid ala, between the sphenoid and the maxillary. The external pterygoid alae do not extend transversely beneath the foramen ovale. The capromys very nearly resembles the preceding genus in the construction of its face, but in it the jugal bone is broader, and almost rhomboidal in its shape. The sphe- noid also is in contact with the maxillary, above the point of union between this bone and the pterygoid portion of the palatine. Fig. 257. Skull of the Porcupine (Hi/strix cristata). In the common porcupine {Hystrix cristata, Lin.), the bones of the nose are very large and broad, the suture connecting them with the frontal mounts much higher up than the inter- maxillary sutures. The intermaxillary bones have their ascending ramus much less narrow than in the preceding genera. The maxillary is hence a pre-orbital ring, which is much broader than it is high ; and the inferior horizontal por- tion of its circumference is much more slen- der than the vertical posterior portion. The lachrymals consist of a small portion situated external to the orbit, which furnishes a little hook-like process, and of another portion situated within the orbit, which is also of small size. The jugal is of moderate dimensions, and broader in front than it is posteriorly ; the palatine is deeply indented, and only sends ofF a little tongue-like pointed process to pene- trate the orbit ; but it completely separates the sphenoid from the maxillary. The internal pterygoid processes end in hook-like ter- minations, the extremities of which are united to the tympanum ; the external ones only re- present a transverse bar, into the composition of which the palatine slightly enters. In the cuendu {Hystrix prehensilis, Lin.), the bones of the nose are short and flattened at their anterior portion ; they are likewise remarkably broad and mount Very high up. The pre-orbital ring is higher than it is^broad. The internal pterygoid process extends as far as the tympanum. In the ursons {Hystrix dorsata, Lin.), the pre-orbital ring is larger than in either of the preceding genera, and^its two arches are of equal strength ; the bones of the nose are short, flat, and one third narrower than those of the cuendu. In both genera, the lachrymal is united, at an early age, both with the maxillary and the frontal. The in- termaxillary suture is straight and almost vertical. In the coni {Myopotamus, Commer- son; Mus coipus, Molin.), the bones of the nose are broad and much elongated ; they do not mount higher than the intermaxillaries. The suture between the latter bones forms a very rounded arch, which is concaved pos- teriorly. The maxillary has the inferior edue of its malar apophysis very much flattened. Jhe pre-orbital ring is large. The palatine is in contact with the maxillary below, but above the sphenoid joins that bone likewise, as in Orycterus and other genera. In the agouti {Chloromys, Fred. Cuv. ; Dasyprocta, Ilig.), the lachrymal, which is larger than in the allied genera, contributes to surround the sub-orbital foramen superiorly, so that the ring formed around this hole by the maxillary is not complete. The lachrymal comes down very nearly as far as the jugal bone, but does not touch it. The jugal itself is very small. The pre-orbital ring is broader than it is high ; and there is, moreover, in- ternal to it, situated upon the cheek just above the commencement of the malar apophysis, a long oval sinus, into which, both before and behind, a rounded canal opens. Inferiorlv, the palate bone advances in a wedfe-like' manner as far as opposite to the first "molar tooth ; it penetrates into the orbit by a thin slip, which separates the sphenoid from the maxillary. The internal pterygoid alaj are pro- longed as far as the tympanum by a broad hook-like process ; the external form simple plates, to the construction of which the pala- tines partially contribute. There is a mem- branous space on each side, at the base of the union between the palatines and the in- ternal pterygoid. In the j^acas {Ccslogenys, Fred. Cuv. ; Cuvia Paca, Lin.), the maxillary portion of the zygomatic arch conceals be- neath It an enormous sinus, which is less deep in very young subjects than in adult animals. This swelhng, which fills up a portion of the 378 RODENTIA. pre-orbital ring, causes the latter to be much elongated transversely. And towards its in- Fig. 258. Skull of the Ccdogijnus. ner angle there is an excavation resembling a long furrow or semi canal, which is really the infra-orbital canal. The jugal is much higher than it is broad ; the palatine extends into the palate as far forward as the first molar tooth : in the orbit it is almost hidden by the projection of the maxillary ; ne- vertheless, it is interposed between that bone and the sphenoid, and at the posterior extremity of the alveolar arch. In the Guinea-pigs (Amsma, Fred. Cuv. ; Cavia, Ilig. ; Musporcellus, Lin.), the lachrymal is large ; but it does not entirely form the upper [root of the pre-orbital ring, and the maxillary is not interrupted at this point. The pre- orbital ringis much wider than itis high. We may remark in this genus both the groove of the paca and the fossa of the agouti ; but the latter is situated higher up, as in the rats. The ascending branch of the maxillary is long and narrow. The bones of the nose are broader in front than behind. The jugal only commences towards the middle of the zygomatic arch ; the palatine, which superiorly does not penetrate either into the orbit or into the temporal region, extends in the palate only as far forward as the interval between the second and the third molar teeth. In the kerodons, a small point of the frontal insinuates itself above, between the bones of the nose and the intermaxillaries, the ascend- ing branch of the latter being very long, and extremely narrow at its origin, in the Bra- zilian species. In this species, likewise, the pre-orbital ring is oval, and much elongated transversely, but formed entirely in the maxil- lary bone as it is in the Guinea-pig ; whilst in the kerodon of Patagonia the lachrymal forms by itself nearly the whole vertical portion of its arch, so that the lachrymal is necessarily of very great size. Posteriorly, the maxillary touches by its apex a long point derived from the temporal external to the palatine ; the latter, however, is enclosed between the sphe- noid and the maxillary, and mounts up into the floor of the oibit, when it is connected with the lachrymal bone. In the palate it is very deeply notched. In the capyhara {Hydi'ochcerus, Erxleben), the jugal is still shorter than in the Guinea- pig. The lachrymal is largely developed at the root of the vertical arch of the pre-orbital ring, but does not assist in forming it. The bones of the nose are very large and rectan- gular. The ascending ramus of the inter- maxillary, on the contrary, is extremely narrow, and is only united by its point to a point de- rived from the frontal. The inferior hori- zontal arch of the ring is broad and flattened, with a little fossa at its base, as in the kero- dons ; the maxillary is connected behind with the temporal, near the glenoid facet, external to the palate bone ; but what distinguishes capybara from them is, that this articulation is much more extensive, and that we cannot see, within, the long pterygoid apophysis and that portion of the palatine alluded to above. The external pterygoid alae are obliterated ; the internal alae terminate by a rounded plate, which is very far from reaching as far as the Fig. 259. Skull of the Capyhara. tympanum. The palatine encroaches upon the palate as far forward as the third molar Fig. 260. 6 Skull of the Chinchilla, h, c, portions of the temporal bone, which is here very remarkable on accomit of the extraordinary development of the tympanic cavity ; e, meatus auditorius externus ; /, the occipital bone ; g, the parietal ; h, h, the frontal ; i, zygomatic portion of the temporal, which in this animal is quite detached from the preceding portions ; k, malar bone ; /, ossa nasi. RODENTIA. 379 tooth, and is interposed behind, between the maxillary and the sphenoid. In the viscache and the chinchilla, the bones of the nose are oval and elongated ; the ascending branches of the intermaxillaries very narrow at their origin ; but they enlarge as they approach the frontal, as in the jerboas. The maxillary, in both, forms the entire pre- orbital ring ; but in the viscache the vertical portion of the arch is doubled posteriorly, as in the helamys, by an ascending branch of the jugal, by the lachrymal, and by the frontal bones. At the bottom of the ring there is a deep* groove, almost entirely separated from it by a vertical plate, as in the alactaga. In the chinchilla, the jugal does not reach as far as the lachrymal, and in the pre-orbital ring there is only a very superficial furrow, with no ver- tical plate of separation. In both species the Fig. 261. Base of the skull of the Chinchilla, b, b, tympanic portion of temporal bone ; /, occi- pital bone; m, mastoid bone; n, palate bone; o, the sphenoid ; p, the superior maxillary bone. palatine is very deeply notched, it articulates with the maxillary, except externally, where a point of the posterior sphenoid touches the latter bone : moreover, on account of the en- tire absence of the external wall of the ptery- goid fossa, the palatine is found to occupy a considerable space in the floor of the orbit, be- tween the orbital alae and the maxillary : it does not, however, mount upwards, as in the kerodon, between the latter bone and the frontal, to become connected with the lachry- mal. The internal pterygoid apophysis is largely connected with the tympaiumi. Bones of the carjius. — Generally, in the Rodentia, the os magnum is divided into two, as it is in the monkeys ; in the porcupine this is not the case, but there is a supernumerary bone interposed between the os pisiforme and the metacarpal bone of the fifth finger con- nected with the OS unciforme. The hare and some other Rodents have one carpal bone more than the human subject ; it is situated between the scaphoid, the trape- zium, and the os magnum, of which last it appears to be a dismemberment ; but the beaver, the marmot, the squirrel, the rats, and the agoutis have, like the Carnivora, a single bone representing the scaphoid. The supernumerary bone is as large as the ordinary pisiform, and often much larger. Sometimes, as in the jerboa and the marmot, there are two supernumerary bones, so that, on each side of the wrist, there is a bone of equal size out of rank. In the capybara the scaphoid and the semi- lunar bone are united without any supernu- merary ossicle ; a small one, however, exists in the Guinea-pig. The paca, the agouti, and the capybara have the os magnum divided ; these three animals possess, as the rudiment of the thumb, a small bone situated upon the trapezoid, w^ith which it is articulated. In the marmot and the agouti this rudiment is com{)osed of three ossicles ; and there is, moreover, an internal supernumerary bone. Fig. 262. Skeleton of the Hare (^Lepus timidus). 380 RODENTIA. In the order Rodentia the structure of the thumb differs in different genera ; there is a complete but short thumb in hares, beavers, and jerboas ; an incomplete thumb, consisting of only two phalanges, in squirrels, rats, por- cupines, pacas, and agoutis ; and a thumb, represented by only a single ossicle, in the capybara, the Guinea-pig, the marmot, &c. In connection with the fore-arm it may be observed, that the rabbit has only one pronator of the wrist, corresponding to the pronator teres; a circumstance easily accounted for by the very small degree of motion permitted between the bones of the fore-arm ; in most other Rodentia, however, both the pronators are present. 263. Skeleton of the Beaver (^Castor Fiber). The terminal phalanges of the fingers are generally very slender, elongated, almost straight, and pointed, except in the capybara, which has its last phalanges of a triangular shape, and enclosed in strong horny hoofs. In those Rodentia which have a complete clavicle, the muscles of the shoulder resemble very nearly in their disposition those of the human subject. The humerus resembles that of the Carnivora in its mode of articulation with the fore-arm ; but in those genera that are without clavicles, the articu- lation of the elbow joint resembles more nearly what is met with in herbivorous quad- rupeds, being a simple hinge joint. The hu- merus of the beaver is much expanded at its ulnar extremity, and the deltoid crest is pro- In the Rodentia the general form and posi- tion of the pelvis is nearly similar to what exists in the Carni- vora. The femur is in the beaver very broad, flattened from before to behind, and exhibits along its outer surface a sharp crest, which represents the linea aspera, and which is pro- longed towards its middle into an apophysis, which has been named the third trochanter. This third trochanter is also met with in other rodents, as, for example, in the musk rat ; in the hares it is placed so high up, that it ap- pears to be a derivation from the great trochan- Fig. 2G4. Skeleton of the Flying Squirrel (^Fteromys volitans). longed inferiorly into a prominent point ; a circumstance which is likewise observable in the rat, the water vole, the ondatra, and in many other genera. In the hares, the porcupine, the paca, and the agouti, the humerus near the elbow joint is completely perforated. ter ; in other genera, as in the water vole, the rats, the squirrels, and the marmots, it is a simple crest, or ex- ternal iinea aspera ; in all the Rodentia the great tro- chanter is very prominent, and the neck of Skeleton of the Paca ( Ccelogenys Paca). The Rodentia have the Jibjila situated quite behind the tibia ; in rats, voles, jerboas, the beaver, the helamys, and the rabbit, it becomes consolidated with the tibia towards the lower third of its length, a wide triangular space being left between the two bones at the upper part of the leg ; the anterior crista of the tibia in all the above genera is remarkably prominent, as is the internal edge ; and upon Fig, 266. that, viewed from behind, the tibia exhibits, in the upper half of its length, two deep fossae for the attachment of the tibialis posticus and the flexor longus pollicis. This struc- ture is more particularly remarkable in the 07idatm. In the beaver the fibula gives off from its upper extremity a strong recurrent apophysis, which is directed slightly outwards. In some genera the fibula is excessively slender, and does not reach so low down as to become connected with the lower extremity of the tibia. In those Rodents which have the fibula con- solidated with the tibia towards its tarsal ex- tremity, the tarsus seems to be articulated with the latter bone only ; but if very young Skeleton of the Jerboa (^Dipus hersipes). (^Altered from Pander and D^Alton.^ individuals are examined carefully, it is per- ceptible that the external malleolus is tbrraed by the fibula. In Rodentia the os calcis is very much elorg ted posteriorly. In such genera as have five complete toes the following circumstances may be remarked : In the beaver the os scaphoides is divided into two portions, one placed in front of the astragalus, which supports the second and third cuneiform bones, and one placed inter- nal to the astragalus, to which is attached the cuneiform bone that supports the great toe, 382 RODENTIA. and a supernumerary flattened bone situated along the inner margin of the tarsus. The same disposition of these bones exists in the genera spahix and capromys, in the marmot, squirrels, and porcupines ; but in the four latter genera the supernumerary bone is of smaller size. The rats and the paca have their os sca- phoides divided, but are without any super- numerary bone. Among ^those genera which have only four toes, such as the helamys, or Cape jerboa, which has its foot exceedingly elongated, the inferior tubercle of the scaphoid, which is observable in the sole of the foot of all rodents, is very long and prominent. Upon the internal margin of the tarsus there are in this animal some elongated flat bones, which are the rudiments of the great toe. In the jerboas, properly so called, both the internal and external metatarsal bones are ex- tremely small, and the three others are con- solidated into one bone, upon the distal ex- tremity of which are three articulating surfaces which support the phalanges of the toes. In the rabbit and the hare, animals which resemble the jerboa in the great size of the tubercle of the scaphoid, the rudiments of the great toe become consolidated at an early age with the metatarsal bone of the second toe. In the capybara, the Guinea-pig, the mara, and agouti, which have only three toes, the internal portion of the scaphoid supports a single bone, representing the cuneiform and a rudiment of the inner toe ; the cuboid like- wise supports a small bone, which is a ru- diment of the outer toe. The disposition of the toes varies considerably in the difi^erent genera of Rodents ; in the beaver, the inner toe is nearly of equal length with the others ; in the marmot, the porcupine, and the rats, it is considerably shorter ; in the paca it is nearly obliterated ; and in the Cape jerboa it is a mere rudiment, consisting of but a single bone ; in the hares not even this rudiment is perceptible. In the capybara, the agouti, and the Guinea-pig both the inner and outer toes are reduced to a single bone. The jerboa (Mus Jaculm) and the alactaga (AIus sagitta ) have their three middle meta- tarsal bones consolidated into one piece. The two lateral toes are distinct in the jerboa, but of comparatively small size ; in the alac- taga they are quite wanting. Teeth. — The distinguishing character of the order of quadrupeds under consideration is the remarkable arrangement of their dental system, by which they are enabled to erode the hardest vegetable substances. The chief food of many genera, indeed, consists of the bark, wood, and even the hard fruits of trees, to devour which necessarily requires great strength of jaw, and such a disposition of their incisor teeth as to convert them into strong chisel-like cutting weapons, the edges of which never become blunted even to the latest period of life. These incisor teeth, called also de7ites scalprarii, are situated in the front of the mouth,' and are generally two in number in each jaw, except in the genus Lepus, em- bracing the hares and rabbits, which possess two small additional incisors, situated behind each of the large ones contained in the upper jaw. Between the incisors and the molar teeth there is a considerable vacant space, by which arrangement the play of the anterior chisels is much facilitated, their action being like- wise materially assisted by the mode of arti- culation of the lower jaw, which allows of considerable movement from behind forwards, and by the great power of the pterygoid and masseter muscles. The molar teeth are like- wise exceedingly strong, and vary considerably in their mode of implantation in the jaw s of different genera. The incisors* are always regularly curved, the upper ones describing a larger segment of a smaller circle, the lower ones a smaller segment of a larger circle; these are the longest incisors, and usually have their alveoli ex- tended below or on the inner side of those of the molars to the back part of the lower jaw. Like the molars of the Me- gatherium, and other teeth of unlimited growth, the implanted part of the long and large incisors retains the form and size of the exposed part or crown to the widely open base, which contains a long, conical, persistent dentinal pulp, and is surrounded by the cap- sule in a progressive state of ossification as it approaches the crown, an enamel pulp being attached to the inner side of that part of the capsule which covers the convex surface of the curved incisor. The matrix is here no- ticed in connection with the tooth, because it is always found in full development and activity to the time of the Rodent's death. The calcification of the dentinal pulp, the de- position of the earthy salts in the cells of the enamel pulp, and the ossification of the capsule proceed contemporaneously ; fresh materials being added to the base of the vas- cular matrix as its several constituents are progressively converted into the dental tissues in the more advanced part of the socket. The tooth thence projecting consist of a body of compact dentine, sometimes with a few short medullary canals continued into it from the persistent pulp cavity, with a plate of enamel laid upon its anterior surface, and a general investment of cement, which is very thin upon the enamel, but less thin in some Rodents, upon the posterior and lateral parts of the incisor. The substance of the incisor diminishes in hardness from the front to the back part of the tooth ; the enamel consisting of two layers, of which the anterior and ex- ternal is denser than the posterior layer, and the posterior half of the dentine being by a modified number and arrangement of the calcigerous tubes less dense than the anterior half. The abrasion resulting from the reciprocal action of the upper and lower incisors pro- * Owen, Odontograpliy, p. 398. RODENTIA. 383 duces accordingly an oblique surface, sloping from a sharp anterior margin formed by the dense enamel, like that which slopes from the sharp edge formed by the plate of hard steel laid upon the back of a chisel ; whence the name dentes scalprarii given to the incisors of the Rodentia. The varieties to which these incisors are subject in the different Rodents are limited to their proportional size, and to the colour and sculpturing of the anterior surface. Thus in the Guinea-pig, jerboa, and squirrel the breadth of the incisors is not half so great as that of the molars, whilst in the coypa they are as broad, and in the Cape mole rats {Bathyergus and Orycteromys) broader than the molars. In the coypa, beaver, agouti, and some other Rodents, the enamelled surface of the incisors is of a bright orange or reddish brown colour. In some genera of Rodents, as orycteromys, otomys, meriones, gerbilla, hydrochaerus, lepus, and lagomys, the anterior surface of the upper incisors is indented by a deep longitudinal groove. This character seems not to influence the food or habits of the species ; it is often present in one genus and absent in another of the same natural family; in mostRodents the anterior enamelled surface of the scalpriform teeth is smooth and uniform. The molar teeth are always few in number, obliquely implanted and obliquely abraded, the lateral series converging anteriorly in both jaws ; but they present a striking con- trast to the incisors in the range of their varieties, which are so numerous that they typify almost all the modifications of form and structure which are met with in the molar teeth of the omnivorous and her- bivorous genera of other orders of Mammalia. In some Rodents the molar teeth are root- less, like those of the wombat, the toxodon, and elasmothere; some have short roots tardily developed, like the molars of the horse and elephant ; and some soon acquire roots of the ordinary proportional length. The Rodents which have rootless molars comprise the families of the hares, chin- chillas. Chili rats, and cavies ; most of the voles, the houtias (^Capromys)y and the Cape jerboa (Helamys). The genera which have molars, with short or incomplete roots, developed late, are Castor (beaver), Hystrix (porcupine), Ccolugcnys (spotted cavy), Danyjyructa (agouti). Spa/ax (blind rat), Myopotamus (coypa), EuryotiSy Accomys, and A2)lodontia. The families of the squirrels, dormice, rats, and jerboas have rooted molars. The differences in the mode of implantation of the molar teeth relate to differences of diet. The Rodents, which subsist on mixed food, and which betray a tendency to carnivorous habits, as the true rats, or which subsist on the softer and more nutritious vegetable sub- stance, as the oily kernels of nuts, suffer less rapid abrasion of the molar teeth ; a minor depth of the crown is therefore needed to perform the office of mastication during the brief period of existence allotted to these active little mammals ; and as the economy of nature is manifested in the smallest par- ticulars as well as in her grandest operations, no more dental substance is developed after the crown is formed than is requisite for the firm implantation of the tooth in the jaw. Rodents that exclusively subsist on vege- table substance, especially the coarser and less nutritious kinds, as herbage, foliage, the bark and wood of trees, wear away more rapidly the grinding surface of the molar teeth ; the crowns are therefore larger, and their growth continues by 'a reproduction of the formative matrix at their base, in propor- tion as its calcified constituents, forming the exposed working part of the tooth, are worn away. So long as this reproductive force is active the molar tooth is implanted, like the incisor, by a long undivided continuation of the crown ; when the force begins to be ex- hausted the matrix is simplified by the sup- pression of the enamel organ, and the dentinal pulp continues to be reproduced only at certain points of the base of the crown, which by their elongation constitute the fangs. The beaver and other Rodents in the second cate- gory of the order, according to the implanta- tion of the molar teeth, exemplify the above condition ; but in the capybara, dolichotis, Fig. 267. Lower jaw of the Porcupine (^Hystrix cristatd). iy incisor tooth ; m, the molar teeth, implanted in the jaws by means of fangs ; incisor tooth ; p, anterior molar. pulp at the base of 384 RODENTIA. and other Rodents with rootless molars, the already been cited ; but in the rootless molars reproduction of the molar, like that of the in- where the folds of enamel extend inwards from cisor teeth, appears to continue throughout the entire length of the sides of the tooth, the the animal's existence. The rootless and per- characteristic configuration of the grinding ' petually growing molars are always more or surface is maintained without variation, as in Fig. 2G8. Upper jaw of the Patagonian Cavy (^Chloromys Patagonicd). t, incisor tooth, laid bare throughout its whole length ; m, p, molar teeth implanted without fangs into arched sockets. less curved ; they derive from this form the the Guinea-pig, the capybara, and the Pata- same advantage as the incisors, in the relief gonian cavy. of the delicate tissues of the active vascular The whole exterior of the molar teeth of matrix from the effects of the pressure which the Rodentia is covered by a cement, and the would otherwise have been transmitted more external interspaces of the enamel folds are directly from the grinding surface. filled with the same substance. In the chin- The complexity of the structure of the chilidae and the capybara, where the folds of crown of the molar teeth, and the quantity of enamel extend quite across the body of the enamel and cement interblended with the tooth, and insulate as many plates of dentine, dentine, are greatest in the rootless molars of these detached portions are held together by the strictly herbivorous Rodents. The crowns the cement ; such folds of enamel are usually of the rooted molars of the omnivorous rats parallel, as in the large posterior lower molar and mice are almost as simple as the tuber- of the capybara, which, in shape and structure, culate molars of the bear, or of the human offers a very close and interesting resemblance subject, which they appear to typif\'. They to the molars of the Asiatic elephant, are at first tuberculate ; when the summits of The partial folds and islands of enamel in the tubercles are worn off, the inequality of the molars of the porcupine and agouti, the grinding surface is for a time maintained typify the structure of the teeth of the rhi- by the deeper transverse folds of enamel, the noceros ; the opposite lateral inflections of margins of which are separated by alternate enamel in the molars of the gerbille and Cape valleys of dentine and cement; but these mole-rat represent the structure of the molars folds, sinking only to a slight depth, are in of the hippopotamus ; the double crescentic time obliterated, and the grinding surface is folds in the jerboa sketch out, as it were, the reduced to a smooth field of dentine, with characteristic structure of the molars of the a simple border of enamel. A similar Anoplothere and Rurainantia. change in the. grinding surface, consequent Although, as has been shown, the molar on age and use, is shown in the molars teeth in many Rodents are rootless and of un- of the souslik, or ground squirrel ; as also limited growth, as in the Edentata, in none in those of the gerbille, and is common is enamel absent ; or vascular dentine, as the to all that possess roots. It will be seen that chief constituent of the tooth, present. These these folds have a general tendency to a trans- essential dirferences characterise the molars verse direction across the crown of the tooth, of those Rodents, which by use have their Baron Cuvier has pointed out the concomitant grinding surface reduced to a simple depres- modification of the shape of the joint of the sion bounded by a raised circular margin, as lower jaw, which almost restricts it to horizontal in the great Cape mole; that margin being movements to and fro, in the direction of the formed by true enamel, but in the sloths by axis of the head, during the act of mastication, hard dentine. When the folds of enamel dip in vertically It is peculiar to some of the Rodents with from the summit to a greater or less depth rootless molars to have the sockets of these into the substance of the crown of the tooth, long curved teeth open at both extremities, so as in those molars which have roots, the con- that, in the dry skull, the base of the tooth figiu'ation of the grinding surface varies with protrudes as well as the grinding surface ; the the degree of abrasion, of which examples have matrix in such instances adheres to the peri- RODENTIA. 385 osteum, which covered the portion of bone absorbed from the bottom of the alveolus. The jumping hare {Helamys copen.sis), when full grown, offers a good example of this cu- rious structure. The molars are not numerous in any Ro- dents ; the hare and rabbit (Lepus) have ; i. e. six molars on each side of the upper 5 — 5 jaw, and five on each side of the lower jaw : 5 5 the pika (Lagomi/s)^ has — - ; the squirrels 5 5 have J — J ; the families of the dormice, the ^ T" porcupines, the spring rats (Echingidce), the octodonts, chinchillas, and cavies, have 4 4 ^ — |- molars; in the great family of rats (Muridce), the normal number of molars is 3 3 X — ^ ; but the Australian water rat {Hydro- o — o 2 9 mi/s) has but - — ^ molars, making with the incisors twelve teeth, which is the smallest number in the Rodent order ; the greatest number of teeth in the present order is twenty- eight, which is exemplified in the hare and rabbit ; but thirty-six teeth are developed in these species, six molars and two incisors being deciduous. In all the Rodents, in which the number of molars exceeds three in a series, the addi- tional ones are anterior to these, and are pre- molars, i. e. they have each displaced a deci- duous predecessor in the vertical direction, and are what Cuvier calls dents de remplace- ment. This it is which constitutes the essential distinction between the dentition of the marsupial and the placental Rodent ; the latter, like the placental Carnivora, Ru- minantia, and ordinary Pachydermata having never more than three true molars. Thus the Rodents, which have the molar formula of 4 4 ^, shed the first tooth in each series ; and this is succeeded by a permanent pre-molar, which comes into place later than the true molars ; later, at least, than the first and second, even when the deciduous molar is shed before birth, as was observed by Cu- vier in the Guinea-pig. In the hare and rabbit the three anterior teeth in the upper jaw, and the two anterior ones in the lower jaw, succeed and displace, in like manner, de- ciduous predecessors, and come into place after the first and second true molars are in use, and contemporaneously with the last molar. It does not appear that the scalpriform incisors are preceded by milk teeth, or, like the pre-molars of the Guinea-pig, by uterine teeth ; but the second incisor was observed by Cuvier to be so preceded in the genus Lepus, and he has figured the jaw of a young rabbit, before that deciduous tooth was shed, when six incisors are present in the upper jaw. This condition is interesting, both as a transi- tory manifestation of the normal number of VOL. IV. incisive teeth in the Mammalia series, and as it elucidates the disputed nature of the great anterior scalpriform teeth. GeofFroy St. Hilaire contended that the scalpriform teeth of the Rodents were canines, because those of the upper jaw extended their fang backwards into the maxillary bone, which lodged part of their hollow base and matrix. But the scalpriform teeth are confined exclusively to the inter- maxillary bones at the beginning of their formation; and the smaller incisors, which are developed behind them in our anomalous native Rodents, the hare and rabbit, retain their usual relations with the intermaxillaries, and, a fortiori, prove the tooth which projects anterior to them to be also an incisor. The law of the unlimited growth of the scal- priform incisors is unconditional, and constant exercise and abrasion are required to maintain the normal and serviceable form and propor- tions of these teeth. When, by accident, an op- posing incisor is lost, or when by the distorted union of a broken jaw the low er incisors no longer meet the upper ones, as sometimes hap- pens to a wounded hare, the incisors continue to grow until they project like the tusks of the elephant, and the extremities, in the poor animal's abortive attempts to acquire food, also become pointed like tusks : following the curve prescribed to their growth by the form of their socket, their points often return against some part of the head, are pressed through the skin, then cause absorption of the jaw-bone, and again enter the mouth ; rendering masti- cation impracticable, and causing death by starvation. In the Museum of the College of Fig. 269. Incisor teeth of the npper jaw of a JRabbif, shoiving the effects of unchecked growth on the sealpriform incisor (i), and the accessory incisor (i, 2). Surgeons there is a lower jaw of a beaver in which the scalpriform incisor has,by unchecked growth, described a complete circle; the point has pierced the masseter nuiscle and entered the back of the mouth, passing between the condyloid and coronoid processes of the lower jaw, descending to the back part of the molar teeth, in advance of the part of its ow n alveolus, which contains its hollow root. The upper jaw of a rabbit with an analogous abnormal growth of the scalpriform and acces- sory incisors is represented in Jig. 269. Organs of digestion. — The order of Rodent quadrupeds comprehends animals which are nourished by various kinds of food, both aninml and vegetable substances forming the nutriment of some genera, whilst others live exclusively upon the fruit, bark, or leaves of c c 386 RODENTIA. trees, or upon tender succulent plants. The differences observable in the structure of the stomach and intestinal canal correspond to the variety of their food, and bear a relation to the structure of their dental apparatus. Fig. 270. Cheek pouches of the Canada Rat ( Geomys bursarius^. Some genera, as, for example, the Canada rat (fig. 270.) are remarkable for the pos- session of capacious cheek pouches, in which considerable quantities of food can be stored up, and which, like the crop of birds, may be considered as reservoirs, wherein nutriment can oe retained preparatory to its introduction into the stomach. The type of stomach most common in this order is the following : the stomachal bag is formed by two distinct pouches, which are more or less separated from each other ; one portion, situated to the left of the cardia, is placed longitudinally, and is generally of a cylindrical or conical shape. This portion is frequently larger than the right portion ; it is lined internally with a thick epidermis, which terminates suddenly, and clearly indicates by its margin the boundaries of this compart- ment of the stomach. The right compartment, which is situated more transversely and further back, is of a conical shape, the apex of the cone terminating at the pylorus. This second portion has its walls thicker and more mus- cular than the former ; its mucous membrane is not hned with epidermis, but presents the ordinary appearance. The distinction be- tween these two portions is indicated ex- ternally by a constriction. The cesophagus enters the first compartment very near to the point where it communicates with the second. Such may be said to be the typical form of the stomach in this extensive order, but many families recede from it to a greater or less ex- tent. In the squirrels (Sciiirus) for example, the stomach is not divided into separate cavities, but is of a pyriform or oval shape, giving off a conical or cylindrical portion, which ter- minates in the pylorus. The first compart- ment is hned internally with a thick epi- dermis, which foi'ms two oval lips, as it is prolonged around the opening into the second compartment, the lining membrane of which is simply mucous, without any apparent epi- dermic covering. The ondatras (Fibcr^ Cuv.), campagnols (Arvicolaj, and the lemmings (Geoiyckiis, llinger), present a similar ar- rangement. Stomach of the Water Vole {Arvicola amphibius'). g, oesophagus ; a,f, cardiac extremity of the stomach ; c, its median constriction ; b, dilated pyloric extre- mity of ditto ; e, pyloric pouch ; h, i, duodenum. In the Hudson's Bay lemming (Mus Hnd- sojiius, Gm.), the shape of the stomach is slightly different, it is situated transversely and much elongated, without any division into cavities ; the cardia opens at about the upper third of its anterior border ; the left cul-de-sac is cylindrical and of uniform size with the pyloric portion, which is bent for- ward and to the left side. The stomach likewise varies from the com- mon type in the jerboa (Dipiis, Gm.), and in the leaping hares of the Cape {Helami/s). In the former it is globular, in the latter pyriform and longitudinal, with a large cardiac cul-de sac directed forwards, a pyloric cul-de-sac, and a short c\lindrical pyloric portion, which is bent forwards. The rat moles (Spa/ax, Guldensledt) are approximated to the lemmings and to the campagnols in the shape of their stomach, which is divided into two pouches, having the oesophagus closely approximated to the pylorus. In the muscardin (21. avellenarius, L.) the stomach offers a peculiarity in its struc- ture, which distinguishes it not only from the other species of this genus, but also from all other Mammalia, — the cesophagus imme- diately beyond the diaphragm terminates in a globular pouch, the walls of which are thick, glandular, and exhibiting internally numerous pores leading into crypts : this structure is separated by a constriction from the stomacii properly so called. This latter organ forms a large cul-de-sac of a slightly oval shape, which gives off anteriorly, and to the right side, a short bowel-like pyloric portion. In this animal, therefore, there are two stomachs, one of which corresponds with the glandular stomach of birds, as will be seen further on. The beaver exhibits traces of this structure. The stomach of the hamster (Cricefus, Cuv.) approximates the common type de- scribed above, the stomach being divided into two pouches, separated by a deep constric- tion ; the left pouch is cylindrical, the right globular. The cardiac orifice is situated in RODENTIA. 387 the former to the right of its base, opening on the constriction itself, so that aliments can pass immediately into the second compart- ment by the assistance of a fold, which is pro- longed from the cardia into this cavity ; and the pyloric portion may be distinguished, which is more muscular than the rest, and ter- minates in the intestine by a slightly pro- minent pylorus. The Cape mole {Bathiergus, Iliger) like- wise conforms to the preceding type of struc- ture ; the left compartment of the stomach is of enormous size, elongated and pierced at its base by the cardiac orifice ; the left com- partment is of smaller dimensions, of a glo- bular form, and separated from the preceding, both by an external constriction and an in- ternal fold of the mucous membrane. There are, moreover, two additional folds nearer to the pylorus, which seem to form a third compartment. The orycteres of the Downs (Bathiergus viaritimiis) has its stomach slightly different ; its position is more longitudinal, so that the left compartment is anterior, and the right posterior ; the pyloric portion short, cylindrical, and directed forwards. In the beaver {Castor) the stomach is transverse and elongated in that direction, the right portion being larger than that which is situated to the left of the cardia • the oesophagus is inserted into the first third of its anterior margin by a narrow opening, sur- rounded with pointed processes, which are analogous to the fringes formed by the epi- dermis in many other Rodents. At the point where it terminates around the opening of the first compartment of the stomach into the second, numerous largely developed culs-de- sac are distinguishable, which project more or less beyond the cardia in different individuals. On the right of this orifice commences the pyloric portion, the termination of which is indicated by an external constriction, and by an internal thickened ring. The pylorus is approximated very closely to the cardiac orifice. This pyloric portion, which is more muscular than the rest, is sometimes dilated into a distinct pouch, separated by a con- striction from the pyloric cul-de-sac. The internal membrane presents every where the same appearance, except that in the pyloric portion it appears to be more smooth, and its folds take a different direction. On the right of the cardia there is a very thick fold, sepa- rating the left from the right compartment. In the rabbit and the hare {Lepus, Lin.) the stomach is very much elongated, par- ticularly in that portion which is situated to the right of the cardiac orifice. This latter portion forms a bulb, the muscular wall of which is thicker than elsewhere, especially in the vicinity of the pylorus, where it is swollen into a muscular ring. In the other parts of the stomach the existence of this layer is scarcely perceptible. In the lagomys (Cuv.) we have again the common type of structure, as also in the agoutis and the pacas. In the pteromys (F. Cuv.) the stomach is situated more transversely, and the two culs- de-sac are more distinct ; the right compart- ment is the hirgest, and gives off at an angle a short conical pyloric portion. In the sciuropteres (F. Cuv.) the stomach is round, deep from before to behind, and having the bottom of the cardiac culs-de-sac formed into a little pouch, and extending slightly beyond the cardia ; the pyloric portion is conical, very muscular, and lined internally with a yellowish mucous membrane, whilst the lining membane of the rest of the stomach is white and arranged in folds, which form arches parallel to the curvatures of the viscus. There are two other folds running longi- tudinally on the right and on the left of the cardia, but which probably do not exist when the stomach is distended t these would seem to indicate traces of a division of the cavity into three pouches. In the dormice (Mt/oxus, Gm.) the stomach differs in shape in accordance with the appe- tites of the different species. In the common dormouse (^Mus Glis, Lin.) it is conical, with a small pyloric portion directed forwards ; its membranes are thick and muscular, approxi- mating the type of a carnivorous stomach. In Mt/oxus Nile/a, on the contrary, it is globular, and consists of a single sac ; the crypts, the orifices of which open into the cavity of the stomach, form a thick disc in the vicinity of the cardia : these crypts are evidently small culs-de-sac, formed by the mucous membrane and the cellular layer beneath it, which here appear folded upon themselves in irregular festoons, when a section of this glandular disc is examined. The ligneous substances upon which the beavers feed have rendered neces- sary this superabundance of the secretions furnished by this gland. A constriction se- parates the pyloric portion from the re- mainder of the straight part of the stomach. The pylorus consists of a prominent ring projecting into the intestine. In the family of the porcupines (//y^/W.r, Lin.) we have another example of the dif- ferences which the stomach may present in different genera. In the cuendu (St/nef/iercs, F. Cuv.) this viscus resembles that of the orycteres of the Downs, above described ; it is elongated, longitudinal, with one compart- ment anterior and the other posterior ; the oesophagus is inserted into the right side ; the cardia is placed far back, and approximated to the pylorus ; the pyloric portion is short, cyhndrical, and directed forwards, terminating by a ring, which projects into the intestine. In the European porcupine {Hystrix cristafay Lin.) the stomach is globular, forming from before to behind a deep and wide bag. Intestinal canal. — The tract of the small intestines offers nothing remarkable in the Rodentia ; its w^alls are very thin, and its diameter pretty even throughout. On coming to the large intestines, the most striking fea- ture is the enormous size of the caecum, which, in many genera, itself fills up a great proportion of the abdominal cavity. There are, moreover, many interesting modi- c c 2 388 RODENTIA. fications to be noticed, both in the construc- tion of the caecum and of the commencement of the colon, which generally presents the same appearance as the caecum itself for a short distance from its commencement. The greater or less development of the caecum is in relation to the nature of the food appropriate to each individual. In one genus only, namely, the dormouse (Mi/oxics), it is altogether wanting ; those Rodents that live upon grass and herbs have it most remark- ably developed ; and in the hare it has been calculated that the capacity of the caecum is ten times as great as that of the stomach itself. In the granivorous genera its size is likewise very considerable ; so that, in the hamsters, lemmings, Guinea-pigs, and aUied genera it has been estimated to be four times larger than the stomach. Another remarkable peculiarity may be observed in the caecum of the Rodentia, namely, that it frequently has its cavity divided into regularly arranged cells disposed in several rows, or else forming a single series. In other cases the cavity of the cjEcum is divided into compartments by a broad spiral Fig. 272. CCEcum of the Squirrel. a, termination of the small intestine ; b, d, the caecum ; e, dilated commencement of the colon. valve, as is the case in the hares ; or, as in the marmots, by circular folds of its lining membrane. In some species again, as in the jerboa, &c., the interior of the ca^cum is a simple cavity, without any division or internal complication. All these diversities of struc- ture seem to be in relation with the different kinds of food devoured by these animals. The proportionate length of the small in- testine as compared with that of the large, is frequently the reverse of what holds good in carnivorous quadrupeds ; but the diameter of the latter, except in the immediate vicinity of the caecum, is scarcely greater than that of the small intestine (Jig. 273. m, n). The intestinal villi have the shape of leaf- lets of fringed laminae, or sometimes of very fine filaments ; the entire inner surface of the small intestine is villous, whilst that of the large intestine is quite smooth. Fig. 273. Stomach and intestinal canal of tlie Rat {Miis Rattus). f, oesophagus ; a, b, d, compartments of the stomach ; e, pylorus ; g, h, i, small intestine ; k, /, caecum ; p, commencement of the colon ; m, n, colon ; o, anus. It is worthy of observation that in those species that have the caecum most largely de- veloped, that organ is furnished with very remarkable glandular appendages ; this struc- ture is met with in the genera Lepus and Lagomt/s. In order to illustrate the above general deseription of the digestive organs "of the order of quadrupeds under consideration, we shall select a few examples illustrative of the principal varieties which it presents in dif- ferent genera. In the squirrel (Sciiirus) the small intestine (fg- 272. a) is nearly of the same diameter throughout ; the ceecum (b, c, d) is of mo- derate dimensions, of a conical shape, and destitute of any cells or partitions internally. RODENTIA. 389 The colon (e) is for a short distance almost of the same diameter as the caecum, but it soon diminishes in size, and throughout the rest of its extent is scarcely wider than the small intestine. Internally, it presents no septa or valvulae conniventes. The intestinal papillae form small lamellae, the borders of which are fringed w^ith delicate filaments ; these papillae extend throughout the whole length of the small intestine, but towards its termination becomes smaller and less per- ceptible. In the rats, the alimentary canal would be nearly of the same calibre throughout, were it not for the interposition of the caecum between the ileum and the colon. The caecum in this family of Rodents rather re- sembles a second stomach (Jig. 273. k, /) than a bowel ; it is capacious, short, and slightly curved upon itself, but without any constric- tions, tapering gradually towards its blind ex- tremity. The walls of the intestinal canal are throughout thin, delicate, and transparent ; Fig. 274. C(Ecum of the Water Vole {Avicola amphibius). l, m, end of the small intestine ; n, o,p, q, caecum ; r, dilated commencement of the colon ; s, point at which the colon becomes contracted. but slight traces of a spiral valve are visible at the commencement of the colon. In the water-rat {Arvicola amjMb'ms) the small intestines are of equable diameter throughout their whole extent, but their calibre is small, as indeed is that of the large intestine. The caecum is, however, of enor- mous proportions {fg. 274:. n, o, p, q), and is divided at intervals into pouches by deep constrictions. The commencement of the colon (?) is extremely voluminous, but it soon diminishes in its diameter, and is twisted in a remarkable manner, so as to form several close spiral turns ; the walls of the small in- testine (/, ni) are very thin and transparent ; at the commencement of the colon its lining membrane is thrown into regular folds, which, as they appear through the transparent coats of the intestine, resemble a series of spiral muscular fibres. In other species belonging to the genus arvicola, the same disposition is observable. In the Cape moles (Bathiergus) the struc- ture of the caecum varies. In the orycterus of the Downs {Bathiergiis marithmis) the* caecum is short, and has its walls sacculated and puckered up, as it were, by tendinous bands. The colon begins by a wide pouch, and preserves through nearly its whole length a considerable diameter and sacculated ap- pearance, but on approaching the anus it be- comes contracted and of equable diameter. In the white-spotted orycterus (Bat/iiergus capensis) the caecum is much longer in pro- portion and of more equal calibre, although still very wide, in proportion to the size of the small intestine, and much sacculated; the com- mencement of the colon is at first of the same diameter as the caecum, but it soon be- comes narrower and spirally convoluted, much in the same way as in the water-rat. In the hare and in the rabbit the small intestine is nearly of the same diameter throughout its whole length ; the caecum is of a very remarkable size, and forms an enormous elongated conical sac, divided, at intervals, by deep constrictions into numerous compart- ments, as far as about the distance of two or Coccum of the Hare. c, termination of the ileum ; a, d, a spirally convoluted ciecum ; 5, d, its temiinal glandular portion ; f dilated pouch, close to the termination of the small intestine ; e, capacious commencement of the coloa which, at g, becomes considerably diminished in size. c c 3 390 RODENTIA. three inches from its extremity 275.). The constrictions, apparent externally, correspond to the windings of a spiral valve, which runs nearly along the whole length of its cavity. The small intestine, at the point where it is about to enter the colon, dilates into a cavity (/), the w alls of which are thick and glandu- lar. At its- commencement (e) the colon is quite as capacious as the caecum, but it soon begins to contract in its diameter, (g) At its commencement there are three rows of sacculi, divided by as many tendinous bands, but further on these sacculi disappear. The rectum is much dilated, and contains, at in- tervals, small pellets of excrement moulded in the sacculi of the colon. In all the species belonging to this genus, as well as in the rats and hares, including the Lagomys, the ex- tremity of the caecal bag, opposite to that which receives the termination of the small intestine, is terminated by a long, smooth, cylindrical appendage {fig. 275. d, b) the walls of which are glandular, and somewhat resemble those of the glandular stomach of a bird. The above examples will suffice to put the reader in possession of the general structure of the alimentary canal in the rodent order of quadrupeds ; and for farther details we must refer him to the last edition of Cuvier's Le9ons d'Anatomie comparee, where the principal varieties met with in the different genera are recorded. Liver. — In the Rodentia the liver is very largely developed, and presents the usual division into five principal lobes. The gall- bladder, though generally present, is some- times wanting, a circumstance more particu- larly observable in the family of rats. Another circumstance which may be noticed is that the bile is frequently poured into the intestine at a point remote from that where the ])ancreatic fluid enters it ; when such is the case, the biliary secretion enters the duodenum very near to the pylorus, above the entrance of the pancreatic duct. In the porcupine the ductus communis choledochus is formed by the union of two hepatic canals with the cystic duct; it enters tlie intestine close to the pyloric ring, opening into a furrow excavated in the latter, in such a manner that the bile would seem to flow as easily into the stomach as into the duo- denum. The opening of the pancreatic canal is at a considerable distance from the pylorus. The fjancrcas is very large, and generally divided into two portions. The spleen occupies its usual position sus- pended from the stomach by the gas^ro-splenic omentum. The lymphatic system of the Rodentia con- forms in all respects to the usual arrangement of these vessels met with in other quadrupeds, and exhibits nothing worthy of particular remark. The arterial system, as far as the general distribution of the blood-vessels is concerned, offers a few peculiarities worthy of notice. In all those genera of rodent quadrupeds wliich become dormant during the winter months, the vertebral artery considerably surpasses in size the internal carotid ; to such an extent, indeed, that some authors have described the latter vessel as being entirely wanting. In this case the basilar artery forms by itself a very considerable part, and some- times the whole of the circle of Willis, giving off the anterior cerebral arteries as well as the posterior arteries of the brain.* The arrangement of the carotids, moreover, varies remarkably in different genera. In the beaver the internal carotid is larger than the vertebral. In the porcupine the internal carotid, after following for some distance the direction of the internal maxillary, without undergoing any sinuous flexures, enters the cranium through the foramen lacerum anterius, where it immediately joins with the basilar, which surpasses it in size, to form the circle of Willis. In the Guinea-pig and the agouti there is, properly speaking, only an external carotid, of which the mternal carotid is but a small branch. This little cerebral branch is derived from the internal maxillary, of which it seems to be a continuation ; it enters the cranium through the foramen ovale of the sphenoid bone, and joins the circle of Willis, which is here principally formed by the vertebral artery. In the squirrel the internal carotid enters an osseous canal in the tympanum, through the jugular foramen, passes between the crura of the stapes, and then penetrates the cra- nium through a hole in the petrous portion of the temporal bone ; it there divides into two branches, the smaller of which enters a deep groove in the os petrosum, issues from the cranium through the foramen lacerum an- terius to enter it again through the oval foramen of the sphenoid bone. It is only after all these windings that it divides into small branches, and of these only one or two go to form the circle of Willis, the rest being meningeal arteries. The continuation of this branch subsequently becomes the representa- tive of a portion of the ophthalmic artery. The other branches usually given off from the ophthalmic artery are derived from the second branch of the internal carotid above mention- ed, which previously gives off branches to the dura mater. It will thus be seen that the in- ternal carotid supplies very little blood to the brain, and this blood only arrives at its desti- nation by a very circuitous route, f In the marmot the internal carotid at first follows the same course as in the squirrel ; it enters the canal of the tympanum through the jugular foramen, and then traverses the opening between the crura of the stapes, after which it divides into two branches : of these the internal, which is the smallest, runs * Vide Memoire sur les vaisseaux cephaliques de quelques niammiferes qiii s'en coui'dissent pendant I'hiver, par M. Otto, Anuales des Sc. Xatur, t. xi. p. 200. t Vide Barkow, Disquisitiones circa originem et dccursum arteriaiiun auimalium. Lipsise, 1829. RODENTIA. 391 through an ascending canal, which enters the cavit} of the skull close to the sella •turcica, arriving at the brain much in the same manner as the internal carotid of the human subject. This branch is smaller than the vertebral artery. The other or external branch enters the cranium through a canal that opens upon the anterior surface of the petrous bone, and divides into the middle meningeal and ophthal- mic arteries. In the dormouse the distribution of the internal carotid very nearly resembles what is described above, as occurring in the squirrel and in the marmot. In some genera of Rodents the internal condyle of the os humeri is perforated by a canal through which the ulnar artery passes in company with the median nerve : this arrangement exists in the squirrel, the hamster, and the helamys. Venous system. — In most of the Rodentia, instead of a single anterior vena cava, there are two principal anterior trunks of the venous system, one of which, namely the right, occu- pies the usual position of the vena cava anterior, whilst the left runs along the furrow that separates the base of the ventricle of the heart from the left auricle, to reach the right auricle, into the upper and left side of which it opens. In those genera which hibernate the exter- nal jugular vein likewise presents a very remarkable arrangement. This vein receives a considerable proportion of the blood de- rived from the brain through a wide canal, situated between the os petrosum and the temporal bone, into which the anterior division of the transverse sinus opens, so that it is only the smallest moiety of blood derived from the vein which escapes through the jugular for- amen into the internal jugular. The vertebral vein likewise communicates with the external jugular, carrying off its share of the blood from the interior of the cranium. Fig. 276. Upper surface of the brain of the Porcupine. (After Serres.) a, medulla spinalis ; b, hemispheres of cerebellum ; c, median lobe of the cerebellum ; d, e, h, I, cere- bral hemispheres. Although this disposition of the cerebral veins is common to all hibernating animals, as Cuvier very justly remarks, it is by no means peculiar to quadrupeds that pass the winter in a state of torpor ; on the contrary, it is met with in many Rodents that do not hibernate ; as, for example, in the rats ; it also occurs in the horse, as well as in many Edentata, Ru~ mhiantia, and Carnivora. Cuvier believes this arrangement to be in relation with the situ- ation and direction of the head, the differ- ence between these quadrupeds and man rather depending upon the position of the latter standing on four legs, than upon any cause connected with the habit of hiber- nation. Nervous si/stem. — The brain in the Rodent order of quadrupeds presents two principal forms ; in the feebler, and more strictly her- bivorous species, such as the hare, the rabbit, the agouti, paca, «&c., it presents a great re- semblance externally in its shape to that of birds, the cerebral hemispheres being broad behind, and gradually tapering towards the anterior lobes. In others, such as the beaver, porcupine, capromys, &c., the contour of the brain is nearly circular {fig. 276.), as in car- nivorous quadrupeds. Between these extreme forms there are, however, intermediate grada- tions, such as are met with in the squirrel, the marmot, the water-rat, and others. Fig. 277. Base of the brain of the Porcupine (Histrix cristata). (After Serres.) a, anterior pjTamid, exhibiting the interlacement of their internal fasciculi ; o, olivary bodies ; t, tra- pezoid bodies ; p, pons Varolii ; ti, the lobe of the hippocampus ; g, middle portion of the hemisphere ; r, olfactory tract ; x, external root of olfactory lobe ; 2/, internal root of ditto. The nerves are indicated by corresponding numbers. The most striking circumstance presented by the brains of these animals is the almost complete deficiency of cerebral convolutions. The hemispheres are almost completely smooth upon their surface, presenting only a few shallow lines instead of the numerous sulci which characterise the brain of the Car- nivora. c c 4 392 RODENTIA. The cerebellum is of moderate proportions, and is scarcely at all overlapped by the pos- terior lobes of the cerebrum. Fig. 278. Upper surface of the brain of the male Agouti {After Serres.) «, the medulla spinalis ; b, posterior pjTamid ; c, median lobe of the cerebellum; d, hemisphere of cerebellum ; e, cerebral hemispheres ; /, olfactory- lobe of the brain. On separating the hemispheres, the tuber- cula qiiadrigemina (^g. 280. 8, 9) are seen to be of very large size ; and, what is re- Fig. 279.] Saseof the brain of the male Agouti. (^Afler Serves.) p, pons Varolii ; h, lobe of the hippocampus ; g,f, lateral portion of cerebral hemisphere ; k, anterior part of the lobe of the hippocampus ; e, olfactory lobe ; u, infundibulum. The nerves are indicated by corresponding numbers. markable, the anterior pair (nates) are of a roundish form, and much larger than the pos- terior pair (testes) (8) ; a circumstance which is the converse of what exists in carnivorous quadrupeds. In other respects the structure of the brain in the Rodentia offers no pecu- liarity worthy of special notice. The organs of the senses conform strictly in their anatomical structure to the general type common to mammiferous quadrupeds, and consequently need not occupy our attention in this place. Fig. 280. Interior of the brain of the same animal. (After Serres.) a, medulla spinalis ; b, restiform body ; c, arbor vitte cerebelli ; 1,2, 3, 4, 5, 6, ramifications of ditto ; d, superior peduncle of the cerebellum ; 7, nervus patheticus ; 8, posterior quadrigeminal tubercle ; 9, anterior quadrigeminal tubercle; 11, optic tract; 12, posterior pillar of the fornix ; 13, corpus stria- tum ; n, corpus callosum ; i, f, g, horizontal section of the hemisphere on a level A\'ith ditto ; Z, ?», lateral portion of the cerebral hemisphere. The structure of the hdnet/s, and the gene- ral disposition of the urinary apparatus afford nothing deserving particular description. Alale organs of generation. — The Rodentia are amongst the most prolific of all quadru- peds ; a circumstance which may, perhaps, account for the extraordinary development of the appendages to the male generative system, which are met with throughout the order. It is, indeed, difficult to identify the precise ana- logies of some of the accessory genital organs, which are much more complex in structure than those of other Vertebrata. In the greater number of Rodents, as for instance in the rats, the Guinea-pigs, the agoutis, the porcupines, the beaver, the onda- tra, and the squirrels, the testicles are not contained in a scrotum, but during the season of impregnation are lodged beneath the skin of the perineum, which is tightly stretched over them. In the hares, however, two dis- tinct scrotal pouches exist (Jig. 281. k, I), situated in the vicinity of the anus, in which RODENTIA. 393 the testes are contained. The testes are moreover, remarkable for tneir great size, Fig. 281. Male generative organs of the Hare. a, glans penis ; 6, body of penis ; c, prostate gland ; d, vesiculae seminales ; e, the urinary bladder ; /, g, testicles; h, i, epididymis; k, I, the two scrotal pouches ; p, q, vasa deferentia. which generally exceeds that of the kidneys ; a circumstance which is more remarkably evident during the season of copulation. From the testicles situated as above, the vasa deferentia ascend into the abdominal cavity, along with the spermatic vessels, through the external abdominal ring. In some tribes, a little above their insertion, the walls of the vasa deferentia become manifestly thicker, and the cavity of their duct considerably dilated ; in some cases they join together, and seem to form but one canal ; but this appearance is merely external, the ducts continuing separate throughout their whole length. The vesiculcB seminales, or their analogues, exist in all the Rodentia. In the hares they are simple bags {fig. 2S\ . d) ; but, generally speaking, their cavity is more or less convo- luted, or branched out into caeca, as, for ex- ample, in the agouti (fig. 282. ?, 0, and in the beaver {fig. 284. o,p). In most of the genera of this order of quadrupeds the vesiculae seminales are remarkable for their great de- velopment; in the Guinea-pig they form two long conical tubes, which taper much towards their extremities, but are slightly sacculated for a portion of their length ; the excretory ducts in this animal open into the urethra by an orifice common to them, and to the vasa deferentia. In the agouti each opens separately into the common cavity of the verumontanum , in which are also situated the separate orifices of the vasa deferentia, and of the excretory canals of the accessory vesicles ; so that all these canals are brought into communication by means of this chamber. In the Alpine marmot, the vesiculae semi- nales contain internally a very complicated cavity, the walls of which are glandular. In the rats, properly so called, the vesiculae seminales consist of large membranous blad- ders of a flattened conical form, with their inner margins sacculated and uneven, some- thing like a cock's comb. In these animals they are in great part situated out of the pel- vis on account of their very la ge size ; in the hamsters, the voles (ylm'co/^s), the dormice, and the jerboas they present a similar structure, and become remarkably developed during the season for copulation. Fig. 282. The generative organs of the male Agouti. a, a stylet introduced into the cul-de-sac, at the extremity of the penis; b,b, serrated bony plate, situated on each side of the glans penis ; c, c, vasa deferentia ; d, the body of the penis ; e, e, the pro- states -jf canal of urethra laid open ; g, h, a style in- troduced through the prostatic duct into the ure- thra ; i, i, the vesiculie seminales ; I, m, a wire passed along their duct k, into the urethra ; o, o, Cowper's glands, communicating -\ath the urethra by means of the duct, p, into which a style q has been passed ; n, the anus ; r, anal gland with the style, s, t, passed into its duct. In the hare and in the rabbit these organs are represented by the single sac already alluded to {fig. 281. d), the size of which is considerable ; this sac is of a triangular shape, two of its three corners being sometimes con- siderably elongated ; its walls are membranous, except for about two thirds of its upper side, where they are formed by a thick glandular substance something resembling in texture the prostate gland. This sac opens into the urethra by a single orifice excavated in the centre of the verumontanum, which receives 394 RODENTIA. likewise the terminations of the two vasa defe- rentia. In the lagomys (Lepus piisillus, ogotonusy and alphmsy Pall.) the vesiculae seminales are double and separate. In the common squirrel each seminal vesicle consists of a short canal folded upon itself. This approximates its fellow on the opposite side between the prostate and the canal of the urethra ; and, contrary to what is usual in this order, internal to the vasa deferentia. The prostate glands. — The name of pro- state gland is restricted by Cuvier to those glandular masses of analogous structure to the human prostate, the excretory canals of which open by one or several orifices into the com- mencement of the muscular portion of the urethra, or into the first portion of that canal. In some cases, however, the representatives of the prostate are made up of numerous rami- fied and complicated tubes, in which case they are called tubular prostates. In the hare and the rabbit, this gland is represented by the glandular mass, which, as above described, forms a portion of the walls of the vesiculae semi- nales, and which extends for some distance upon the muscular portion of the urethra {fig. 281. c). Fig. 283. 3Iale organs of the Water Vole {Arvicola amphibius). a, glans penis ; c, the urinary bladder ; d, e, the testicles ; /, g, epididymis, situated at some distance from the testes ; k, I, vesiculae seminales ; m, n, o, p, q, r, the prostates ; s, the rectum, the extremity of which is suiTounded by a glandular mass, t, from ■which a milky fluid is povu-ed into the rectum in the vicinity of the anus, v. In the Alpine marmot it forms a consider- able mass situated above the commencement of the urethra, divided posteriorly into two roundish lobes. In the squirrel the prostate gland is as long as the muscular portion of the urethra, to which, however, it is only adherent at the two points where its excretory ducts penetrate that canal ; in this animal its shape is oval, flattened above, and bilobed posteriorly. In the agouti the prostates {fig. 282. e, e) assume the tubular form, each gland being composed of a common trunk, divided into branches and ramusculi, ending in vascular enlargements. In the numerous family of rats, the pro- states are represented by several packets of ramified tubes, situated around the com- mencement of the canal of the urethra. Two others are connected with the inferior surface of the vesiculae seminales : these consist of a principal trunk, which has but few ramifica- tions. These latter organs exist likewise in the lagomys, and may perhaps be considered accessory seminal vesicles. The Guinea-pig is furnished with numerous ramified and convoluted tubes, connected to- gether by a loose cellular tissue, which occupy the situation of the prostate gland ofother quadrupeds. Fig. 284. Generative organs of the male Beaver. a, opening common to the rectum and the urethral canal ; h, the prepuce ; c, glans penis enclosed in the prepuce; d, body of the penis; e,f,g,h,{,k, preputial glands ; I, bifurcation of corpus caverno- sum foruiing the bulb ; 7ti, n, Cowper's glands ; o^p, vesicular seminales ; q, urinary bladder ; r, s, testicles ; t, V, vasa deferentia. Cowper's glands. — Most of the Rodentia are provided with accessory glands, which, in situation at least, correspond with those called the glands of Cowper in the human subject. In the male Agouti, these glands are two round, flattened, and very vascular bodies {fig. 282. o), which open into the bulb of the urethra by separate ducts (p). In the Guinea-pig their structure is similar, as likC' RODENTIA. 395 wise in the beaver, only they are of much smaller proportionate size. In the squirrel, Cowper's glands are repre- sented by two large conical bladders twisted upon themselves, the summits of which are evidently of a glandular nature, and are divided internally into numerous small cells. Each of these organs opens by a large orifice into a cid-de-sac, which occupies the interior of the hu\h of the urethra, and which is pro- longed into a canal, that, becoming gra- dually narrower, opens into the urethra near the angle formed by the bend of the penis. The walls of the conical bladders, which con- stitute the substance of these glands, contain muscular fibres, which serve to constrict their cavities. In the Alpine marmot and in the boback, these glands present a similar structure. In the rats they are of very large size and of a pyriform shape, their substance being en- veloped in an aponeurotic sheath. Penis. — The penis in the Rodentia is dif- ferently arranged in different genera. In the Guinea-pig and the agouti, this organ, after running forwards in the ordinary manner as far as the anterior margin of the symphysis pubis, bends back again upon itself beneath the skin of that region towards the anus, so that the opening of the prepuce is situated very little in front of the anal orifice. Mus- cular fibres, derived from the creraaster mus- cles, are inserted into the penis near its curva- ture ; and others, derived from the external obhque muscle of the abdomen, are connected with the same point. The former probably contribute to effect the protrusion of the penis from its sheath, whilst the latter draw it back again into its concealment. In the marmot, the penis, when it arrives in the sub-pubic region, does not bend back again to approximate the anus, but curves directly downwards ; in which position it is retained by ligamentous attachments. In many genera of Rodents, as, for example, in the rats, the voles, the dormice, the jerboa, the hares, and the lagomys, the penis, after issuing from the pelvis, does not run forwards beneath the symphysis of the pubis, but passes directly backwards towards the anus, imme- diately in front of which the orifice of the prepuce is situated (Jig. 281. a). In most of the Rodentia the penis contains a bone, imbedded in the substance of the corpus cavernosum. But the most remark- able part of the penis in the order before us, is the glans, which in many species is armed with such a formidable apparatus of spines, saws, and horny spikes, that it must indeed be a rather stimulating instrument of excitement. In the Alpine marmot it is conical, and terminated by a sharp point, formed entirely by the extremity of the os penis. On the right of this point is situated the opening of the urethra, and on the left there is a small but deep cul-de-sac. In the common rat, the extremity of the penis, in its relaxed state, resembles a second prepuce, there being here a wide cavity exca- vated in the centre of the glands, enclosing a bone, the extremity of which projects beyond it, and is furnished with two small, cartila- ginous, lateral appendages. Beneath this is situated the cavity of the urethra. Most of the genera allied to the rats, such as the hamsters, the voles, the dormice, &c., have their penis constructed upon the same plan ; but in some the surface of the glans is smooth, whilst in others it is covered with papillae, or studded with fine hairs. The glans penis of the beaver is cylin- drical in shape, but flattened at its extremity, which is studded with large papillaj, the orifice of the urethra being situated near its centre. In the Guinea-pig, the penis is supported by a flat and slightly curved bone imbedded in its upper portion, which reaches as far as the extremity of the glans above the canal of the urethra. Behind and below the termi- nation of the urethral canal is a wide pouch, in the bottom of which are lodged two long cartilaginous horns. This pouch, during erection, is everted, so that the horns pro- trude externally. Two tendons are connected with the bottom of this pouch, which run along the penis inferiorly, and are connected with a thin layer of muscular fibres, derived from the bulb of the urethra and the rami of the corpora cavernosa. These tendons, either by their own elasticity, or by the action of the muscular fibres connected with them, serve to invert the pouch and draw it back again within the glans. The whole surface of the glans is covered with corneous scales, which, with the two horns above mentioned, give it a formidable appearance. Fig. 285. Penis of the spotted Cavy ( Cfive genera and eight families. The Rotifera, undoubtedly, deserve to be called Infusoria as much as the Polygastria, as they are found very generally with the latter in various kinds of infusions. There are some circumstances, however, under which the Polygastria are developed, in which no Rotifera have yet been found : thus the Polygastria have been found inhabiting water, containing sulphuretted hydrogen and other gaseous constituents, where no Rotiferous ani- malcules have been found at all. As a general statement, it is true that the Rotifera are the last to appear in infusions ; but there are many instances in which Polygastria are developed without the subsequent appearance of Rotifera, and they disappear from infusions sooner than the former. Of the 722 species of Infusoria, described by Ehrenberg, he found that forty - one only were commonly present in the various artificial infusions, which he made in various parts of the world. Of these only three species belonged to the class Rotifera, viz. Co- lurus uncinatus, Ictht/diinn podura, and Lepa- della ovalis. It is the appearance of these animalcules in infusions, which among other things have led to the question of equivocal ge- neration (Generation); but whateverground the low organisation of some of the Poly- gastria might afford for a belief in this doc- trine, the Rotifera have an organisation too high to allow of doubt on this point. The fact of creatures so highly developed being produced in infusions, would create a doubt with regard to the whole theory of equivocal generation, which only positive observation could set aside. The Rotifera, although classed with the Po- lygastria as *' infusory animalcules," must not be regarded as performing a common function with them in the economy of creation, for not only are there fewer species of Rotifera, but they also exist in much smaller numbers. 398 ROTIFERA. Whilst the Polygastria descend in structure to a point where it may be well questioned, whether they partake most of the animal or vegetable character, the Rotifera have always' a decided animal character. The Polygastria are even said to perform functions, such as the absorption of carbonic acid and the evo- lution of oxygen, which would seem to throw doubt on their animality altogether ; but no such function can possibly be attributed to the Rotifera. They appear to be distributed as widely on the earth as the Polygastria ; and Ehrenberg has recorded their existence in various parts of Europe, Asia, and Africa. They have also been found in America. They inhabit both salt water and fresh, although the species which inhabit the latter are by far the most numerous. Like some of the higher animals, the same species are found inhabiting both salt and fresh water, whilst others are peculiar to brackish water. Although they are capable of pursuing their way in the open water, they are generally found swimming around, or attached to, the leaves and other parts of aquatic plants. In our own country the leaves of Ceratoi)hyllum are found to be a favourite resort of species Limnias^ Alasti- gocerca, Dinocharis, Moiiura^ and others. The floating roots of the various species of Lemna are also the favourite resort of several species, whilst others are found in abundance amongst the fibrilliform fronds of the fresh-water algoe. Some of them even take up their residence in the interior of the cells of plants. Roper first discovered them in the cells of Sphagman obtusifolium. Subsequently Unger described a peculiar movement in certain tubercles which he had observed to be developed upon the stalk of Vaucheria clavata. The same phe- nomenon was witnessed by Professor Morren, of Liege, who, on investigating the subject more closely, found that the movements of the tubercles was due to the presence in their interior of the Rotifer vulgaris. Others, again, are found in turfy and bog waters ; whilst some, especially the species of Notommata, are found parasitic upon other animals. The Rotifera are more susceptible to the in- fluence of either high or low temperatures than the Polygastria. Ehrenberg observed the latter constantly come to life after the water in which they were contained had been frozen. Species of Diglena, Metopidia, ColuriiSy and Lepadella frequently came to life after they had been frozen for a short time. Other species experimented on, as Hydatina senfa, Brachionus urceolaris, and s{)ecies of Salpina, all died. Although they are easily destroyed by being frozen, some of them will bear a great variety of temperature. Thus the Phi- lodina roseola, which we have found in the streams of Yorkshire, has been discovered by Professor Agassiz amongst the red snow of the Alps, where it must have been exposed to a much lower tempeiature than in the former habitat. Polygastria bear also a higher de- gree of heat than Rotifera. Brachionus urceo- laris and Hydatina senta were found alive after having been exposed for thirty seconds to a temperature of 104° Fah. Higher tempera- tures speedily destroyed them. One of the most remarkable points in the economy of the Rotifera is the power they possess of recovering their vitality after having been apparently perfectly desiccated. This fact was first made known by Leeuwen- hoek, who, at the same time that he disco- vered the existence of the common Rotifer, had an opportunity of observing this remark- able property. In one of his original papers, contributed to the Royal Society of London, he says : — "In October, 1702, I caused the filth or dirt of the gutters, when there was no water there, and the dirt was quite dry, to be ga- thered together, and took about a teacupfid of the same and put it into a paper upon my desk, since which time I have often taken a httle thereof, and poured upon it boiled water, after it had stood till it was cold, to the end that I might obviate any objection that should be made, as if there were living creatures in that water. These animalcula, when the water runs off them or dries away, contract their bodies into a globular or oval figure. After the above-mentioned dry substance had lain near twenty-one months in the paper, I put into a glass tube, of an inch diameter, the remainder of what I had by me, and poured upon it boiled rain water after it was almost cold, and then inmiediately viewed the small- est parts of it, particularly that which sub- sided leisurely to the bottom, and observed a great many round particles, most of which were reddish, and they were certainly ani- malcula ; and some hours after I discovered a few that had opened or unfolded their bodies, swimming through the water ; and a great many others that had not unfolded them- selves, were sunk to the bottom, some of which had holes in their bodies ; from whence I concluded that the little creature called the mite had been in the paper, and preyed upon the aforesaid animalcula. " The next day I saw three particular ani- malcula swimming through the water, the smallest of which was 100 times smaller than the above said animalcula. "Now, ought we not to be astonished to find that these small insects can lie twenty-one months dry, and yet live, and as soon as ever they are put into water fall a swinnning, or fastening the hinder parts of their bodies to the glass, and then produce the wheels, just as if they had never wanted water. In the month of September I put a great many of the last- mentioned animals into a wide glass tube, which placed themselves on the sides of the glass presently, whereupon I poured the water out, and then observed that several animal- cula, to the number of eighteen or nineteen, lay by one another in the space of a coarse sand, all which, when there remained no more water, closed up themselves in a globular figure. " Some of the bodies of these animalcula were so strongly dried up, that one could see the wrinkles in then), and they were of a ROTIFERA. 399 reddish colour ; a few others were so trans- parent, that if you held them up between your eye and the light, you might move your fingers behind them, and see the motion through their bodies. " After that these animalcula had lain thus dried up a day or two, I invited some gentle- men to come and partake of the agreeable spectacle with me, that is, to see how the said animalcula would divest themselves of their globular figure, and swim about in the water. According to which, after my friends had satisfied their curiosity in viewing the animal- cula in their oval or globular form, some of which were so pellucid as if they had been little glass balls, I poured some water into the glass tube, whereupon they presently sunk to the bottom, and then the gentlemen took the said tube into their hands, and viewing it one after another through a microscope, they saw the animalcula, after the space of about half an hour, beginning to open and extend their bodies, and getting clear of the glass to swim about the water, excepting only two of the largest of them, that stayed longer on the sides of the glass before they stretched out their bodies and swam away." Since the period that Leeuwenhoek made these observations, this subject has been one of great interest to naturalists ; and a question has been raised as to the condition of the dried animalcules. Leeuwenhoek seems first to have raised this question, by declaring that complete desiccation must involve the death of an animal, and as it could not come to hfe after once dead, that the revivified animalcules were not completely desiccated. The experi- ments of Leeuwenhoek were repeated by other observers, and the same results obtained. Needhara not only saw it in the Rotifers, but also in the Vibrio of bhghted wheat. His opi- nion was, that the desiccation was quite com- plete. Needham's experiments were repeated by Baker, who also came to the same conclu- sion. These observers were followed by Spallanzani, who, in a most elaborate series of investigations, confirmed the conclusions at which Needham and Baker had arrived. He, however, points out the fact, that the re- vivification of the animah'ules was much more constant when they were dried with sand than when dried on a smooth surface. He found also that animalcules when in this desiccated state would bear a much greater heat, as well as a much more intense degree of cold, than when in an active state. Animalcules that, whilst living, would not bearahigher temperatare than 100° Fahr., when dried were resuscitated after having been exposed to a temperature of 144° Fahr. They also recovered after being ex- posed to a degree of cold 24° cent, below zero. Although numerous facts of the same kind were recorded by subsequent observers, the accuracy of these observations have been doubted by several eminent naturalists, at the head of whom stands Bory St. Vincent, who, in the article Rotiferes, in the Dictionnaire Classique d'Histoire Naturelle, says, that the desiccated animals have not been resuscitated at all, but that they are developed from eggs, in the same way as the Daphnia and other minute entomostracous Crustacea are de- veloped after the first shower of rain which falls on the soil in which their ova are con- tained. The correctness of these observations can now hardly be doubted ; and since the time that Bory St. Vincent wrote, a great number of observers of undoubted accuracy, have repeated the experiments of Spallanzani and others, and have arrived at the same con- clusions. Doyere, a French naturalist, pub- lished a very extended series of investigations on this subject, in the Annates des Sciences Naturelles for 1842, in which various species of animalcules were perfectly desiccated and resuscitated under circumstances which would entirely prevent the supposition of a develop- ment such as was suggested by Bory St. Vincent. Experiments of the same kind have been performed by observers in our own country. Dr. Carpenter says, " In the sum- mer of 1835, I placed a drop of water con- taining a dozen specimens of the Rotifer vulgaris on a slip of glass, and allowed the water to dry up, which it did speedily, the weather being hot. On the next day I ex- amined the glass under the microscope, and observed the remains of the animals coiled up into circles ; a form which they not unfre- quently assume when alive, but so perfectly dry that they would have splintered in pieces if touched with the point of a needle, as I had observed before in similar experiments. I covered them with another drop of water, and in a few minutes ten of them had re\'ive(.), and these speedily began to execute all their regular movements with activity and energv. After they had remained alive for a few hours, I again allowed the water which covered them to dry up, and I reviewed it on the following day with the same result. This process I re- peated six times ; on each occasion one or two of the animals did not recover, but two sur- vived to the last, and with these I should have experimented again had I not acciden- tally lost them." Professor Owen in his Lectures, after alluding to the experiments of Professor Schulze on this subject, says, " I myself wit- nessed at Freiburg, in 1838, the revival of an ArctiscoHy which had been preserved in dry sand by the professor upwards of four years.'' We must, however, quote one great authority against the view that a perfect desiccation of the resuscitated animals has ever taken place, and that is Professor Ehrenberg him- self. He does not go so far as Bory St. Vincent, but regards the desiccation spoken of as an assumption, and supposes that the rotiferous and other animalcules which are re- vivified have the power of living in both water and air; although they do not perform their functions so actively in'the latter, yet that they still perform them. He says that he has seen the stomachs of Rotifera filled with granules of a conferva which was growing in the sand in which they were supposed to have been desic- cated. Although we feel that the opinions of 400 ROTIFERA. Ehrenberg on the subject of animalcales are en- titled to great respect, we think that he has not investigated this subject with the candour that would entitle his conclusions to confidence. There is no a jpriori evidence why a perfect desiccation and suspension of the functions of life should not take place. This is the natu- ral condition of the embryo of the seeds of many plants, which, after hundreds of years, when placed in proper circumstances, will exhibit all the functions of vegetable life. Amongst the highest forms of animals we often witness a suspension of the functions under special external circumstances, which, although not amounting to the extent found amongst the Infusoria, would yet prepare us to admit a far more intense degree of the same phenomenon amongst those beings in which animality was less decided, and the vegetative functions more predominant. There is no necessity to regard the condition of desicca- tion in which those animals may be placed as one of death. The conditions of the exist- ence of the vitality of the animal, whatever they may be, are undoubtedly secured in this state, and the conditions of the activity of this vitality are alone withdrawn. Although many of the species of Polygas- tria are as large as the Rotifera, the structure of the latter is much more easily discernible, on account of the transparency of the lorica, or shield, in which they are enclosed, and the distinctness of their individual organs. The external coverins, though always clear like some instances forming a homy kind of case, insusceptible of movement, and, in others, a skin susceptible of transverse corrugations. Into this dense external membrane the animal is capable of drawing in its tail and rotatory organs; hence this ^class of animals has been called Systolides. In none of the species does there' appear to be a deposit of earthy salts, either in the skin or other parts of the body.* This will account for the fact, that few or none of the Rotifera have been found in a fossilised state. Those forms alone of the Polygastria have been dis- covered in the chalk and subsequent forma- tions, which, in their living state, possess a si- hceous or calcareous skeleton. In the classification of the Rotifera we shall follow Ehrenberg, as no separate ar- rangement of these creatures existed previous to his profound investigation of their struc- ture ; and although other attempts have been made, since the appearance of his work, on the Infusoria, none of them seem better adapted for the purposes of further inquiry. At the same time we would, with the utmost diffi- dence, express our doubts as to the correct- ness of much of the terminology employed by Ehrenberg, implying, as it frequently does, views of the structure and functions' of the parts of these animals which the facts them- selves, so remarkably correctly observed, do not always seem to warrant. ' The following is a table of the eight families of Rotifera according to Ehrenberg : — crystal, has varying degrees of density, in fMargins of the wheek CMoLOTRO- j ^^^^ loricated. entire. CHA.) Margins of the wheelsi -nt i ^ crenated. (ScHizo- f ^^^^I , TROCHA.) jLoncated. . , T -1 1 fManv-parted -wheels, "i Naked. A compound, or divided, [ (PoLyxROCHA.) } Loricated. A single, continuous, ci- liated wheel. (MOXO- TROCHA.) (SO- ciliated wheel EOTROCHA.) t GOTROCHA.) It will at once be seen that this is an exceed- ingly artificial arrangement ; for although the rotatory organs are the most striking external character of the Rotifera, the function they per- form does not seem to be of that fundamental importance in the economy of the animal, so that a change in their form would be attended with corresponding changes in their general structure. In fact, in this arrangement, forms are separated which are nearly related by the affinities of more important organs. In the next place, the families are arranged accord- ing as they are naked (panzerlose), or loricated (gepanzerte). The condition of the integu- ment here employed as a means of classifica- tion, cannot be regarded as absolute ; and there are species which it w^ould be difficult to refer to either group. Some of the species secrete around them an external tube, in which they dwell, as Stephanoceros ( 'fg. 292.) and others, which is an entirely different thing from the hardened integument called by Ehrenberg the lorica, or shield, and yet these are classed as a loricated family. It is, however, but due to Ehrenberg to state that Icthydina. (Ecistina. Megalotrochcea. Flosctdaria. HydatincBa. Euchlanidota. PhilodiruEa. BrachioTUBa. I Two-parted wheels. (Zt-1 Naked. L GOTROCHA.^ J Loricated. he is not unaware of the defects of this ar- rangement, and that he has pointed out that both the structure of the alimentary canal, and even the teeth and jaws, would afford characters by which the species might be arranged. Dujardin, in a recent work on the Inftisoria, proposes the four following fami- lies : — 1. Rotifers having the posterior part of their bodies Jixed. Examples : Flosctdaria^ Stephanoceros. 2. Rotifers having but one means of loco- motion, that of the vibratile ciha, and which are consequently always sivimmers. Exam- ples : Plygina, Lacitmolaria, Ale/icej-ta. 3. Rotifers which have two modes of loco- motion : one creeping like the leech, the other swimming as the last. This family includes the largest number of genera, as Brackionus, Dinochdi'is, Pterodina, Salpina, Lejjadel/a, Euchlanis, &c. * Ehrenberg states that the remains of some Rotifera having been chemically examined ; they were found to contain phosphate' of lime, which he supposes was deposited in their jaws and teeth. ROTIFERA. 401 4. Rotifers without vibratile cilia, but which are supplied with nails, by means of which they walk. Examples : Hydatina, Notom- matay Furcularia^ S^c. Dujardin, in his work, also objects to the characters on which Ehrenberg has consti- tuted the various genera belonging to his eight families, these genera being principally determined by the presence or absence of little red spots, which Ehrenberg designates as eves. (^Fig. 292. a ; fig. 303. a ; fig. 296. a ; fig. 294. a ; fig. 298. a ; fig. 299. b.) The following is a description of the families adopted by Ehrenberg : — Family 1. — Icthydina. Character. Naked Rotifers, with a single continuous rotatory organ, not lobed at the margin. In the genera Ptygura and Glenophora^ the rotatory organ is circular, and serves as a means of locomotion. In ChcBtonotus and Icthy- dium it is elongated, elliptical, band-like, and seated on the ventral surface. ChcBtonotus and Icthydium possess a furcated foot, Pty- gura and Glenophora a simple one. Icthydium and Chtstomttts have a simple conical intes- tine, with a long thin oesophagus without teeth (?) Glenophora, a short oesophagus with two teeth; Ptygura,dL constricted stomach with three teeth (jifg.288.). Pancreatic glands are only seen in ChcBtonotus and Ptygura. Caecum, gall-ducts, and male sexual organs not observed. In two genera, the female sexuaj system consists of an ovarium with a few large ova. The evidence of the existence of a nervous system is seen in the two large red frontal eyes of Glenophora. Chaetonotus has a hairy back. Analysis of the genera : — 'A single foot. Ptygura. A furcated] j- , j- ,^ foot. ] Icthydium. ChcBtonotus. Fig. 288. Eyes ab- sent. Two eves. No hair. Hairv. Glenophora. These genera embrace six species, some of which have been known to microscopic ob- servers under various names, from a very early period. Icthydium podura was described by Joblot, as poisson a la tete treflee, in 1718. The Chcstonotus larus was described by Miiller in 1776 as Trichoda acarus. This family embraces some of the simplest forms of the Rotifera. It may perhaps be doubted as to whether this class at all is the place for the genus ChcBtonotus. They have no distinct rotatory organ, and their bodies covered with cilia, place them in very close alliance with some forms of the Polygastria, especially the Euplota, from which they are distinguished by their symmetry, and distinctly furcated tail. Dujardin places CJuEtonotus amongst his symmetrical Infusoria, which do not include the Rotifera or Systolides. Family 2. — CEcistina. Character. Ro- tiferous animals, with a single rotatory organ entire at the margin, enclosed in a shield. The organs of motion consist of internal muscles and an entire foot or tail. The or- gans of nutrition are an apparatus with rows VOL. IV. Ptygura melicerta. {After Elirenberg.') 1, partially expanded ; 2, completely expanded, the cilia in action causing currents indicated by the arrows ; 3, contracted. a, a, a, contractile vesicle ; b, situation of the anal orifice. of teeth for chewing (/g. 289. «, a), two pan- creatic glands. Ova and ovaria have been Fio. 289. Conochilus volvox. (^After Ehrenberg.') a, a, jaws and teeth ; b, b, papillai ; c, c, c, c, glands ; d, d, ovarium, observed in the two forms of which the family consists. Vessels, two filiform tremulous or- gans (called by Ehrenberg "gills"); nervous D D 402 ROTIFERA. fibres, with ganglia, are seen in Conochiliis, and two red eyes are seen in both genera, r Confined to an in- Lorica, or shield. J dividual. (Ecistes, L Common to many. Conochilus. In the less circular rotatory organ than in Ptygura we see the tendency in these animals to the more compound forms of that organ. The lorica, in this family, is not homologous with this organ in many of the other loricated species ; but a case formed by a secretion from the surface of the body of the animal, as is seen in some Annelides, and occasionally in the aquatic larvae of insects. The social habit of Conochilus is very remarkable in this group, as many as forty individuals being frequently found together, attached by their tails, and the consequence of the action of their rotatory organs is a circular movement of the whole mass {fig. 290.). This habit is not confined to Conochilus amongst the Roti- fera ; but it is interesting as connecting this class in habit with the compound Polygastria on the one side, and the Cirripedia and com- pound Ascidia on the other. Fig. 290. The animals of Conochilus volvox, half contraeted, forming a circle. {After Ehrenberg.^ Family 3. — Megalotroch(EA. Character. Monotrochous rotatory animals, with the mar- gin of the rotatory organ incised or flexuous, not inclosed in a shield. The flexuous extended rotatory organ is used for locomotion, swimming, and the sup- ply of nutriment. Muscular bands are evident in the interior, by which the form of the body is changed. In Megalotrocha, the alimen- tary canal is supplied with a stomach, two caeca, jaws with a double row of teeth, and two pancreatic glands. In the other two species there is a single canal, without sto- mach or caeca. Microcodon has jaws with two teeth. Cyphonautes is toothless. The re- productive organs consist of an ovarium. The ova in Megalotrocha are attached to the parent by a thread. Vessels, and tre- mulous gill-like organs, are observed in Megalotrocha. The organs of the senses are in two genera — the red eyes. Mega^ lotrocha exhibits radiated nervous masses, and above these four dark glandular bodies in the neighbourhood of the mouth. These have been erroneously regarded as eyes {fig. 291.). Analysis of genera. Eyeless. Cyphonautes. ™.. , rOne eye, Microcodon. VVitn eyes. |Two eyes. Megalotrocha. Of these three genera, Megalotrocha is the only one that is well known, or that appears to answer to the description of the family. Cyphonautes is a marine animal, of which Eh- renberg has seen but two specimens. Micro- codon has also doubtful characters. Megalo- trochay of which there is only one species, M. albo-fiavicansy has often been described by the older observers. Megalotrocha fla vicans. (^After JEhrenberg.^ a, a, nervous ganglia ; b, jaws ; c, ovum ; d, d, bodies whose functions are unknown ; e, e, e, e, trans- verse vessels. Family 4. — Floscularia. Character. Monotrochous loricated Rotifers, with a ro- tatory organ, with sinuous lobed or multifid margins. The rotatory organ is divided more or less deeply into two, four, five, or six divisions. In the last case they may be almost said to be compound. The alimentary canal gene- rally exhibits a stomach, and is supplied with jaws and teeth. Floscul-iria has no stomach. Lacinularia has two caeca. Semilunate pan- creatic glands are seen in all the species. A short ovarium, producing a few ova at a time, ROTIFERA. 403 is found near the foot in all the genera. Male organs, as glands, exist in Lac'mularia and MelicertUy perhaps also in Floscularia and Stephanoceros. Vessels are seen in Lacinu- laria. Tremulous gill-like organs in Stephano- ceros and Lacinidaria. Eyes are seen in all F'l^. 292. except Tubicolaria. Nerve-like ganglia may be found in Lacinularia^ Limnias, and Meli- certa. Two pairs of muscles contract the body posteriorly {Jig 5.). Analysis of the genera. Eyes notl present. / One eye. f Wheels 2-parted. younfeO. ^"P""''"'- Wheels 6-or L G-parted. Fia. Tubicolaria. Stephanoceros* 1 Separate. Limnias. J Segregate. Lacinularia. V Melicerta. Floscularia. 293. ! m Stephanoceros Eichornii. {After Ehrenherg.') a, single eye ; 6, h, nervous ganglia ; c, crop, con- taining a navicula and other infusory animalcules ; rf, jaws ; e, anal orifice ; J\f, ova. Hydatina senta. (^After Ehrenberg.^ a, brain ; b, nervous cords ; c, ganglia ; d, ali- mentary canal, containing infusory animalcules ; e, e, e, e, muscular fibres; /,/,/,/, transverse ves- sels ; g, respiratory orifice h, seminal tubes ; », anal orifice. D D 2 404 ROTIFERA. Although, at first sight, this might appear a very natural group, a little examination of their so-called rotatory organs will^ suggest the propriety of separating from the rest the genera Floscularia and Stephanoceros. The organs which are called rotatory in those ge- nera are evidently, as Dujardin has pointed out, more like to the bristles or setae of the lorica of other species, than to the true rota- tory organs. The cilia, as they are called, of Floscularia, do not move at all. The bristle- like organs of Stephanoceros are covered with cilia, which appear to be vibratile. The lo- ricae of these animals also consist not of the integument rendered horny, but of a case secreted from the outside of the body of the animal. The animal has the power of retiring into this case, and in Stephanoceros this habit, combined with its structure, give to it a strong resemblance to some of the Cilio brachiate Bryozoa. This external resemblance is so great, that many of the earlier observers re- ferred it to the Polypifera. Oken referred it to the hydroid polyps, and placed it between Hydra and Tuhularia. Goldfuss referred it to a position in the same class between Coryna and Cristatella. In the genus Ladnulariay the same ten- dency to association exists, as is found in Conochilus. The genera Floscularia and Stephanoceros constitute the first family of Dujardin. The remaining genera, previously noticed in this and the other families, are referred to his second family. Family 5. — HydatiNjEA. Character. Na- ked Rotifers, with a many-parted rotatory organ. All the species of this family agree in the divided condition of their wheels, which do not consist of a circular or semi-circular row of cilia, but of several distinct rows or circles of such cilia, which are distinctly separated from each other. All the three forms, except Polyarthra, have an elongated pincer-like pro- cess, proceeding from the abdomen, which resembles a tail, but is no proper continuation of the dorsal integument. In many species, a muscular apparatus is visible, by which the form of the body is changed. The nutritive organs in all cases are very obvious. It is mostly a simple conical intestine, which, in the great proportion of species, is without the constriction, which forms a kind of stomach ( Jig. 293. d). Tiiarthra longiseta ( Jig. 297.) is, however, an exception, and exhibits a stomach formed by the constriction of the alimentary canal ; whilst Notommata myrmeleo {Jig. 303. c) with some other species have a kind of gastric enlargement, terminated by a narrow anal ori- fice. The commencement of the alimentary canal, with one or two exceptions, in all the genera, is supplied with jaws and teeth. Pancreatic glands are constantly present. The reproductive system is hermaphrodite. The ovarium {Jig. 303. 0 is elongated ; the eggs few. The male organs consist of two filiform elongated glands {Jig. 303. g), and two contractile vesicles. The ova appear under two forms, one smooth and soft, the other hard and spinous. Kotommata bracliionus, and the genera Polyarthra and Tnarthra, bear their ova, like the Crustacea, attached to their sides. In several of the genera a vascular system has been observed ( fg. 293.//,/,/), in the form of transverse and longitudinal vessels, the latter supplied with the tremulous organs called gills ( fig. 303./, /). With this system, a kind of tap, or simple opening, in the neck {Jig. 293. g) is connected. In fifteen of the genera, the two eyes, with their accompanying nervous ganglia { Jig. 293. c), indicate the exist- ence of a sensationarv system. In Hydatina and other genera, nervous ganglia are seen in other parts of the body. Eyeless. "With eyes. No teeth. With iP9ih |Teeth many. With teeth. i^gg^j^ single. Eye frontal. Analysis of the genera. One eye. Two eyes. Three eyes. Eye in neck. Eyes frontal. Eyes in neck. Eyes sessile. Two frontal pedi- culated, neck sessile. Eyes more fin single heaps, than three. [In two heaps. ital pedi-l I, one inl jssile. J Foot styliform. Foot furcated, f^lj^^^^i^; rilifl frontal i With hooks. ciha trontal. ^ Without either. No foot, divided! fins. J TA furcate foot. fstylifonnfoot. {™ded. Foot furcate. In neck. Two frontal, in neck. one I Enteroplea. Hydatina. Pleurotrocha. Furcularia. Monocerca. Synchceta. Scaridium. Notommata. Polyarthra. Diglena. Triarthra. Rattulus. Distemma. Triophthalmus. Fosphora. Otoglena. Cycloglena. Theorus. This family contains a larger number of very generally diffused ; and Ehrenberg, in his species than any of the others. They are microscopic labours, in many parts of the ROTIFERA. 405 world, observed them in the north of Africa and the north of Asia ; they are commonly distributed throughout Europe. The loca- lities they inhabit are very various, some are found in fresh water, other in salt. They are fond of confervae, and may be easily found nestling among these plants. They some- times are in great numbers, so that they dis- colour the waters in which they exist. The species of Triarthra give a milky opaque- ness to the water in which they are found. The species of Polyarthra are interesting on account of the finlike organs which are de- veloped at their sides, and by which they are able to move about. Several of the Notom- mata are parasitic on other animals, and thus approach in habit some of the higher epizoa. The elongated setae or bristles of the species of Triarthra are also worthy of notice {fig. 297.). Family 6. — Euchlanidota. Character. Loricated Rotifers, with a many-parted ro- tatory organ. All the species of this family are clothed with a lorica, which resembles the exoskeleton of tortoises or crabs. Many of the species are remarkable for the appendages of the shield, as setw in Euchlanis and Stephanops, hooks {uncini) in Colurus, horns {cornicula) in Dinocharis, spurs or respiratory tubes {calcar sipho) in Euchlanis (fig. 294.) and Salpina, a helmet (cucullus), in Stephanops. Most of the species have a furcated foot, some few of them have styliform feet. The interior of these animals is not so well observed as in families where the shield is of a less dense character. A muscular system, consisting of both longitudinal and transverse fibres, and muscles to move the foot, can be seen in most species. The nutritive organs consist of a muscular oesophageal head, furnished with two jaws bearing teeth. The oesophagus is mostly a short tube. In eight genera the alimentary canal assumes a conical form, in the re- mainder it is constricted into a gastric organ. Two round or egg-shaped intestinal glands are present in all the species. The anal orifice is situated at the back of the basis of the foot {fig. 302. a). An ovarium with small ova, in four genera, Euchlanisy Monostyla, Stepha- nopsy and Squainella, are seen, in the form of Fig. 294. Euchlanis iriquetra. a, single eye ; &, band of muscles with transverse striae ; c, ovarium ; d, alimentary canal. D D 3 406 ROTIFERA. two strap-shaped sexual glands and contrac- tionary system is indicated [by the presence of tile \esicles. Traces of a vascular system are eyes, which are visible in ten genera and tiiirty- seen only in a few species. The sensa- three species. Analysis ofihe genera. Eyes sent. ab-| J Eyes pre- sent. One eye in neck. Two eyes frontal. Foot fui'cate. Styliform foot. Furcated foot, r Styliform foot. Furcated foot. rDepressed shield. I Prismatic shield. Shield gaping be-1 neath. | Shield closed be , neath. "^i Shield L homs f Shield horned. without Four eyes. Furcated foot. 'Shield somewhat! compressed or prismatic. J Shield depressed f Hooded, or cylindrical. \Not hooded. Lepadella. Monostyla. 3Iastigocerca. Euchlanis. Salpina, I Dinocharis, Monura. Colurus. Stephanops. Metnpidia. SquameUa. In this as in the preceding family, there can be little doubt that the artificial character, the number and position of the so-called eyes, on which the genera are founded, separates species which are united by much more im- portant characters. Thus Dujardin remarks, that the genera Lejyadella, Metojndia, Sle- pkanopSy and SquameUa are separated only by characters which vary according to the nutrition of the animal and the time of the year. The same remark will apply to many of the genera of the preceding family Hyda- tinaea. The species of this family are found m both salt and fresh waters, and have a wide distribution over the surface of the earth. The genus Lepadella is developed sometimes in stagnant water in such quan- tities as to give it a milky appearance. Family 7. — Philodin^A. Character. Naked Rotifers with two rotatory organs. The body of these animals is mostly of a ten- uiform, cylindrical, or spindle-shape, with false articulations, by which, through its muscles, the animal is enabled to withdraw the parts of its body one within another, hke the tube of a telescope. The double rotatory organ, so evident in Rotifers (^Jig. 301.), is seen in all the species. In every species there is a fur- cated foot. In the genera Callidina^ Rotifer^ Acthiurus, and Plii/odina, appendicular hooks are found on the false articulations (^g. 295.). A muscular system is seen in Callidina, Acti- nuruSy Rotifer, and Philodina, Three of the genera have two jaws with two teeth, and two jaws with a row of teeth. A filiform in- testine, with a vesicular enlargement at the end, is seen in four of the principal genera. Intestinal glands are seen in four genera. The reproductive system is hermaphrodite in four genera, with an ovarium and male sexual glands, and contractile vesicles. The last are only seen in Rotifer and Philodina. These two genera and Actinurus sometimes produce living young. Traces of a vascular system in the transverse vessels of Rotifer oxid Philodina, and also in the respii-atory tube or opening of these genera, and of Actinurus and Mono- lahi^, are seen. Nervous masses are fooind under the eyes. Firt. 295. Philodina roseola. (After Ehrenberg.) a, respirjitory tube ; b, alimentary canal ; c, cel- lular mass; d, terminal intestinal pouch; e, anal orifice. ROTIFERA. 407 Eyes absent. Eyes present. With proboscis,'and appendi- cular processes on foot Analysis of the genera. No proboscis or processes Two frontal eyes LTwo cervical eyes. |Wheels pedunculated. \Wheels sessile. f Two toes Foot with processes. { Three toes. Foot without processes. Two toes. Callidina. Hydrias. Typhlina. Rotifer. Aetinurus. Monolabis. PhUodiiia. This family, which includes the true Ro- tifers of Dujardin, embraces some of the least known, as also the most common, animals of the class. The genera Hydrias and Typhlina were found during the travels of Ehrenberg in Asia. Callidina and Monolabis have been found by Ehrenberg at Berlin only. The Rotifer vulgaris was the first wheel-animalcule ever seen, and is certainly the most com- mon of the whole class. It was described with great accuracy by Leeuwenhoek in in his early papers on its discovery. It is this animal which has also been most fre- quently the subject of the desiccating ex- periments to which we have alluded. Acti- nurus Neptunius was known to the earlier observers of these creatures as the wheel- animalcule with the long foot, on account of the extension of its foot or tail. The Philo- dina, though not an unfrequent genus, was first described by Ehrenberg in 1838. The articulated character of the integument in the fepecies of this family, give them a habit dif- ferent from the rest of the group : by means of their probiscoid mouth and prehensile tail, they can successively grasp the object on which they are placed, and are thus enabled to crawl in the same way as the leech and other Annulosa. The affinity between the Rotiferge proper and the Arctiscon and whole family of Tardigrades, which are not ad- mitted as Infusoria by Ehrenberg, has been pointed out by Doyere ; and there can be little doubt that we have, through this group, a transition from the Rotiferae to the Anne- lida. The Rotifer vulgaris is found very com- monly in the ponds and ditches of England, where it attaches itself to the Confervas, the various species of Lerana, and the Cerato- phyllum, which are so abundant in these places. M. Morren, of Liege, has recently pointed out a curious habitat for this animal. Roeper, many years ago, observed that this animalcule sometimes penetrated the cells of Sphagnuniy and even lived in those parts of the plant which were not immersed in water. Unger described, in 1828, some vesicles in the structure of Vaucheria clavata^ which had the power of moving about spontaneously, and which he discovered were produced by an animalcule in their interior. The subsequent researches of Morren showed that this ani- malcule was truly the Rotifer vulgaris. It seems to prefer such a situation to its liberty, for Morren says, " One day 1 opened a protu- berance gently ; I waited to see the Rotifer spring out and enjoy the liberty so dear to all creatures, even to imprisoned animals ; but no, he preferred to bury himself in his prison, descending into the tubes of the plant, and to nestle himself in the middle of a mass of green matter, rather than swim about freely in the neighbourhood of his dweUing." The species of Philodina are beautiful ani- malcules. P. roseola has a rose colour of its whole body ; and the ova, when deposited, have a reddish colour. The ova of this ani- malcule are deposited in little heaps, which the parent attends to, and even remains with the young ones after they are hatched, which Ehrenberg attributes to a kind of social in- stinct. Professor Agassiz found this creature amongst the animalcules which contribute to the colour of the red snow. It was at one time supposed that this colour was due to a species of Alga, the Protococciis nivalis, Mr. Shuttleworth, of Berne, was the first to an- nounce that he had found, in addition to the cells of a plant, several species of Polygastria, belonging probably to the genus Astasia, Subsequently to this announcement. Professor Agassiz discovered the presence of this ani- malcule in the same situation. The author of this article has found Philodina roseola in com- pany with a red animalcule, apparently a species of Astasia^ in waters slightly im- pregnated with sulphuretted hydrogen. Ehren- berg says this animal sometimes occurs entirely colourless, so that its colour may depend on its food. Family 8, — Brachion^a. Character. Loricated Rotifers, with a double rotatory organ. The external covering of these animals is a. testula, such as is possessed by the tortoises, not a scutellum, as found in the Crustacea. The motory system consists partly of external organs, and partly of internal muscles. The rotatory apparatus is often apparently com- posed of five parts — three in the middle and one on each side.. The latter only can be regarded as the true rotatory organs ; the middle portions are only ciliated frontal pro- cesses. In the genus Synchceta there are two setae in the rotatory organs, which are also possessed by the Brachionsea. Noteus and Brachionus have a furcate foot, Anurcea is foot- less, and Pterodina has a kind of sucker in its place. The nutritive organs are very similar to those of the Hydatinaea and Euchlanidota. Intestinal glands have been observed in all the species. The reproductive organs consist of an ovarium, with a few large eggs, which are not hatched internally, but, with the ex- ception of Pterodina^ are externally attached to the parent after expulsion. The male organs consist of glands and contractile vesi- D D 4 408 ROTIFERA. ties. The vascular system is composed of tremulous gill-like organs, and a respiratory spur or tube in some species. Noteus has no eyes, but a large cerebral ganglion ; the other genera have eyes. Analysis of the genera. Noteus. With eyes. Anurcea. Brachioniis. foot. Pterodina. Eyeless, with furcate foot. One inl Without foot. neck. J Foot furcated. Twofrontaljg^ ^.f^^,^ eyes. J With the exception of Noteus, the genera of this family were known to the older ob- servers. Three species of Anuraea were de- scribed by Midler in 1776, and Joblot disco- vered the Brachionus pala (f g. 296.) in 1716. large quantities that they render the water turbid in which they exist. Doyere has constructed a family which he calls Tardigrades, and which are most properly included in the class of Kotifera. The ani- mals of this family have an elongated body, contractile like that of the Rotifer, with four pairs of short legs, each bearing two pairs of small claws. The ahmentary canal is narrow, prolonged into a siphon at its anterior ex- tremity, with an internal maxillary apparatus, moveable, and consisting of a muscular bulb traversed by a straight canal, furnished with horny articulated pieces. Until this family was investigated by Doyere, it was supposed to consist of but one species, the Water-bear (Wasser-bar)of Eichorn ; but under the name Fig. 296. Brachionus pala. {After Ehrenberg.') a, eye ; b, jaAvs ; c, ovary ; d, d, ova ; e, contractile vesicle ; /, ova attached ; g, g, g, teeth of shell ; h, h, intestinal glands ; i, constriction of alimentary canal ; k, respiratory tube ; /, /, transverse vessels. The Pterodina patma was described by Eic/iorn of Macrohiotus, Arctiscon, and other names, in 1775. The genus Brachionus is, of all the which were supposed to be synonymous, it Rotifers, the most remarkable for the density appears that several animals were confounded, of its lorica. The thickness of this organ pre- for which Doyere proposes the generic terms vents their internal structure from being so Eniydia, Milnesia, and Macrobiottis. These plainly obseived as that of many other genera, animals are found in the same localities as the The species of Brachionus often occur in so common Rotifer, and like it possess the ROTIFERA. 409 same faculty of resuscitation after desiccation. On account of the slow movement of Macro- biotus, they have been called Tardigrada j an objectionable term, because applied to a family higher up in the scale of development. On account of their habit of crawling, and not swimming as the great mass of Rotifers, Du- jardin names them Systolides marchess. They are interesting as connecting the Rotifers, not only with the Annelida, but also, through their four pair of feet, with the higher forms of the Articulata, and on the other side with the Helminthida. Ehrenberg regards Macro- biotus not as a Rotifer, but as an animal re- lated to LerncBa. This epizoon and its con- geners have undoubtedly more affinity with the articulate than with the molluscous tribes ; and the relation of the Tardigrades with the Rotifers establishes for that family a more decided tendency towards the articulate groups than any other. Although the organisation of the Rotifera is included in too small a space to permit of dissection, the transparency of their integu- ments is so great as to permit of an easy ex- amination of their internal organs. From the previous descriptions of the families of this order, it will be seen that their organis- ation is very complicated, and that their size is by no means the measure of their position in the animal scale. Tegumentary system. — The Rotifers are all covered with a resisting tegument, more or less flexible, and which is the last part of the body to decompose. The composition of this tunic, although possessing various degrees of density, appears to be entirely organic ; and the absence of siliceous or calcareous matter will account for these animals being never seen in a fossilised state. The investing membrane is open in front, to allow of the contact of the fleshy interior with the water in which the creatures live. There is, also, an anal orifice. In those species in which this membrane is not hardened, so as to form a shield, it is capable of being folded by the action of the muscles, and possesses a number of false articulations. The anterior part, to which are attached the vibratile ciliae consti- tuting the rotatory organ, is capable of being retracted into, or thrust out from, the rest of the body. All the parts of the body retract within the skin into a kind of globule, when the animal is removed from the water. The tegument has attached to it various organs, as the claws in Emydium, the cirrhi, or fins, of Polyarthra, and the elongated setae of Tri- arthra {Jig. 297.), the teeth in the dense tegu- ment, or lorica, of BracMoiKsa (fig. 296. g,g). The tail, or foot, must be regarded as an elongation of the tegument. It varies much in size and length. Sometimes it consists of a single styliform seta, as in Triarthra longi- seta {fig. 297.) ; in the genera Monura and Monostyla it is styliform, but is also articu- lated. In some of the species of the genus Anuraea there is no tail at all. In most in- stances the tail is forked, as in Hydatina, Etcchlanis, Pkilodina, Rotifer, Brachionus^ Sfc. {figs. 293 — 296.). Sometimes the tail is di- vided from the point of its origin with the tegu- Fis. 297. Triarthra longiseta. (^After Ehrenherg'). a, a, muscular fibres ; h, contractile vesicle ; c, c, intestinal glands. ment of the body, as in Notommata longiseta (/jg. 298.) and in Hydatina senta (fig.293.). More frequently a portion intervenes between the body and the terminal processes. This is soft and movable in every part in Brachio- niis pala (fig, 296.) ; forms a series of sheaths 410 ROTIFERA. in others, as Dlnocharis paupera {fig. 302.), and many of the Philodinaea. The tail is Fig. 298. h Notommata longiseta. a, single eye ; b, anal orifice. often furnished with supplementary setae, or bristles, and in Pterodina it is terminated with a row of vibratile cilia. The tail is used as a rudder, an oar, and a hold-fast. When styli- form, it seems used as a rudder, although in some cases apparently employed to propel the animal. When furcated it has the power of opening and closing the processes on each side, and apparently holding on to any object by their means. Many genera, as ConochUiiSy Floscularia, Stephanoceros, and others, have no fork, but remain fixed by their tails. Even in species which have forked tails, as in the Philodinaea, the creatures seem to have the power of fixing themselves independently of their fork. It would thus seem not impro- bable that the tail in these cases acts as a kind of sucker. Fig. 299. Rotifer vulgaris. (^After Ehrenherg.') G, orifice of proboscis ; h, eyes ; c, probiscoid pro- cess ; d, spur or respiratory tube ; e, jaws ; /, ali- mentary canal; ^r, g, g, g, transverse vessels; h, muscular fibres ; i, i, seminal canals ; *, young animal. ROTIFERA. 411 Projecting from the upper part of the ex- ternal tegument, in many species, is a little process, which Ehrenberg calls a spur, or siphon {Jig. 299. d), and which he thinks is connected with the function of respiration, and therefore calls it a respiratory tube. It corresponds with an orifice in some species (^g.293.g), which Ehrenberg calls the respira- tory orifice. He has also hinted that they may be connected with the reproductive func- tion. Two of these organs are seen in some of the Notommata and other genera, and they are sometimes covered with cilia. Dujardin thinks that they resemble more closely the palpi and antennae of the Entomostraca. The rotatory organs, or wheels, must be also regarded as a portion of the tegumentary system. They are fleshy retractile lobes, covered with vibratile cilia, capable of being contracted or expanded at the will of the animal. The movement of the cilia when the lobes are expanded gives the appearance of a wheel moving upon its axis, an appearance which was a source of much wonder to the earlier observers of these creatures. In addi- tion to the vibratile cilia, there are frequently found, on the rotatory lobes, setae, or bristles, which have not the power of moving. This is the case in Floscularia^ if, indeed, the organs called rotatory in that genus are truly homologous with the rotatory organs in other species. The true homologue of the rotatory apparatus in Floscularia appears to us to be seated within the external ciliated lobes, where an evidently active motion is constantly going on. The form of the lorica varies greatly ; in some species it is flat and depressed, as in Pterodina and Monostyla ; in others it is pris- matic, as in Mastigocerctty or gaping, as in Euchlanis {Jig. 294.). Some species, as Ste- phanoceros {Jig. 292.), Floscularia^ Melicerta^ and others, have a soft skin, very contractile, which secretes externally a case, and which Ehrenberg calls a lorica; but this is essen- tially a different organ from the lorica. Where this case occurs, it seems to stand in the same relation to the animal as the Polypidon of the zoophytes. The animals which form these cases are also fixed, and retract their bodies within their case in the same manner as the Polypiferae. The Floscularia may be compared to the Hydroid Polyps, while Ste~ phanoceros^ with its ciliated tentacula-like pro- cesses, would appear to have a relation with the Ascidoid polyps. Motory system. — As the movements of the Rotifers are rapid and various, so we find their muscular system complicated. The principal organs of locomotion are the rota- tory organs, by which alone the great mass of the Rotifers appear to move. The move- ments effected by these organs are performed principally by the agency of the vibratile cilia. Although no tissue has yet been dis- covered in the cilia of the Rotifera and Poly- gastria. Professor E. Forbes has observed fibrous tissue in the cilia of a species of Me- dusae, and there can be little doubt that the movements of the cilia, like those of organs to which muscles are attached, are of two kinds, one of which is under the control of the will, and the other not. In the Rotifera, the vibratile cilia of the rotatory organ appear to be under the control of the will of the animal. The extension and contraction of the rotatory apparatus is under the influence of longitudinal muscular bands, which are very evident in most of the species {Jig. 293. e, - - - - "2 1000*0 Tiedemann and Gmelin obtained from 1*14 to 1*19 per cent, of solid residue by evapo- rating saliva. From this, 0*25 parts of ash were obtained, of w^hich 0 203 were composed of salts soluble in water, the remainder con- sisting of earthy phosphates. The following is a list of the constituents of the saliva, according to the above-men- tioned chemists : — 1. Water. 2. A substance soluble in alcohol, and in- soluble in water (fat containing phosphorus). 3. Matters soluble both in alcohol and water (osmazome, chloride of potassium, lac- tate of potash, and sulpho-cyanuret of potas- sium. 4. Animal matter soluble in boiling alcohol, but precipitated during cooling, with sulphate of potash and some chloride of potassium. 5. Matters soluble in water only (salivary matter with abundant phosphate, and some sul- phate of an alkali, and chloride of potassium). 6. Matters soluble neither in water nor in alcohol (mucus, probably some albumen, with alkaline carbonate, and phosphate). Mitscherlich gives the following analysis of the saline ingredients of saliva ; Chloride of potassium - percent. 0*18 Potash (in combination with "1 ^.^^ , lactic acid) - - . I 0 09-* Soda 0-024 Lactic acid - Soda (combined with mucus) - 0*164 Phosphate of lime - - - 0*017 Silica 0-015 Simon made an analysis of his own saliva, and gives the following as the result : Fat containing cholesterine - 0*525 Ptyalin with extractive matter - 4*375 Extractive matter and salts - 2*450 Albumen, mucus, and cells - 1*400 Water 991*225 Simon* adopted the following process in order to complete the above analysis. A known weight of saliva was first evaporated to dryness ; the loss of weight thus indicated the proportion of water. The residue was treated with ether, which extracted the fats. The solid mass remaining was next treated with water, which dissolved out the ptyalin, extractive matters, and salts, leaving behind mucus, albumen, and cells. Dr. Wright has experimented on saliva most industriously, and has entered at some length on the peculiarities of ptyalin, but evidently speaks of a very different constituent to that described by Berzelius and Simon. Accord- ing to the mode of analysis adopted by these two latter chemists, the ptyalin of Wright will be estimated with the fatty constituents, among which it most probably holds its proper place. His process of extraction is as follows : — " To pass saliva through ordinary filtering paper, and after filtration shall have been completed, to exhaust the residue with sulphuric ether ; the ethereal solution contains a fatty acid and ptyalin. It is to be allowed to evaporate spontaneously, and the residue left by evapo- ration is to be placed upon a filter and acted upon by distilled water, which dissolves the ptyalin and leaves the fatty acid. If the aque- ous solution be carefully evaporated to dry- ness, the salivary matter will be obtained in a pure state. Ptyalin, thus prepared, is a nearly solid matter, adhesive, and of a yellowish co- lour ; it is neither acid nor alkaline, readily * In framing this article, much valuable informa- tion has been derived from Simon's work on Phy- siological and Pathological Chemistry, translated by Dr. Day for the Sydenham Society.' SALIVA. 417 soluble in ether, alcohol, and essential oils, but more sparingly soluble in water. It pos- sesses the odour of saliva, and is precipitated by diacetate of lead, nitrate of silver, and slightly by acetate and nitrate of lead, and by tincture of galls ; neither bichloride of mercury nor the strong acids precipitate it. The latter de- crease its solubility, and heighten its odour, while alkalies render it more soluble, and give it the odour of mucus. Ptyalin, when pure, may be kept a length of time, at a mo- derate temperature, without undergoing de- composition." According to Dr. Wright, saliva possesses the property of absorbing oxygen gas, and he states that he has known as much as 2*25 times the bulk of the saliva to be taken up. This quality varies, however, in different spe- cimens ; in Dr. Wright's opinion, according to the quantity of carbonic acid gas con- tained in the secretion. He states he has succeeded in obtaining oxygen from saliva by applying heat, and considers its presence of great value in as- sisting the action of the secretion during the process of digestion, inasmuch as he found that, after exposing saliva to oxygen, so as to enable it to absorb the gas freely, he was en- abled to convert, by its use, a much greater quantity of starch into sugar and gum (an action of which I shall hereafter treat), than by using saliva which had not been exposed to oxygen. Dr. Wright's analysis of saliva is as follows : Water ----- 988-1 Ptyalin 1-8 Fatty acid - - "5 Chlorides of potassium and sodium 1*4 Albumen combined with soda - "9 Phosphate of lime - - _ -6 Albuminate of soda - - - -8 Lactates of potash and soda - -7 Sulphocyanide of potassium - "9 Soda ----- -5 Mucus, with some ptyalin - - 2*6 L'Heritier made analyses of saliva as ob- tained from healthy persons, and gives the following as a mean of ten observations on adults : Water - - - 986-5 Organic matter - - 12*6 Inorganic matter - - '9 Of the organic matters 2*5 parts consisted of salivary matter, or ptyalin (probably not the ptyalin of Dr. Wright, but that described by Berzelius and Simon). Saliva of Children. — Observations by L'He- ritier on the saliva of children showed the quantity of water to be greater in early life. He gives the following as the mean of four analyses : Watet- - - - 996-0 Organic matter - - 3*5 Inorganic matter - - -5 The ptyalin contained in the organic matter amounted to only 1*1. VOL. IV. Male and Female Saliva. — L'Heritier states that he could detect no difference between the saliva of men and women. Enderlin has made several analyses of the ashes obtained from different specimens of saliva, and has found them to be similarly con- stituted. In his opinion, the tribasic phosphate of soda it contains is valuable as a solvent of the protein compounds. He denies the existence of alkaline lactates, not only because the ashes of saliva yielded no carbonate in his experi- ments, but because he failed in detecting them by direct observation before incineration. Plis analyses of the ashes of saliva, as obtained from a large quantity of the secretion from dif- ferent persons, yielded the following result : — Tribasic phosphate of soda - - 28*122 Chlorides of potassium and sodium - 61" 930 Sulphate of soda - - - - 2"315 Phosphate of lime 1 Phosphate of magnesia f " - 5*509 Peroxide of iron J The existence of the sulphocyanide of potas- sium in the saliva is a matter of importance, and some difference of opinion is observed among chemists on the subject. The dis- covery was originally announced by Trevi- ranus, who noticed that saliva, when mixed with a neutral solution of the peroxide of iron, produced a dark red colour. This he regarded as produced by an acid, to which the name of "acid of the blood" had been given by Winterl, and which was afterwards known as the sulphuretted chyazic acid of Porrett. Tiedemann and Gmelin examined into this question, and found that the reaction de- scribed by Treviranus really occurred on adding persalts of iron to saliva, and made experiments to discover whether the colour- ation was produced by a sulphocyanide. After lengthened observation, these physio- logists arrived at the conclusion that such was the case, and procured other reactions besides such as were obtained by testing with iron, which satisfied them of the presence af sulphocyanogen. Dr. Wright mentions sulphocyanide of po- tassium in his analysis of saliv^a, and states that its quantity is always increased by locally stimulating the salivary glands, as by smoking or chewing sialogogues. The internal use of prussic acid or salts containing cyanogen in- creases its quantit}'. It is also greatly in- creased by the use of sulphur. Dr. W, says the presence of this salt is best detected in the alcoholic extract obtained from dried saliva. The sulphocyanide of potassium con- stitutes, according to his observations, from 0 051 to 0*098 of the secretion. Kuehn tried to detect the presence of a sulphocyanide in saliva, but failed. He could not prove the presence of sulphur either by the processes of Gmelin or Ure. Miiller, also, w^as not satis- fied by his observations that the red colour produced in iron resulted from the presence of sulphocyanogen. K E 4J8 SALIVA. The properties and physiological uses of the saliva have been examined into by a great number of observers, and we find much valu- able and curious matter for consideration in their general results. General Properties. — Boerhaave and Hoff- man ascribed a peculiar fermentative power to saliva, a subject which was subsequently more fully entered upon by Sir John Pringle and Dr. "Macbride. The former observer experimented on certam anti-putrescent qua- lities of the secretion, and found that raw meat putrefied slower after admixture with saliva. Another experiment of Sir John's deserves description in detail. He took two drachms of fresh meat, and the same quantity of bread, and to these added as much saliva as he supposed might be necessary for digestion. He beat up this mixture in a mortar, then enclosed it in a phial, and set it in a warm atmosphere for about two days. No signs of fermentation could be detected at the end of that time, but during the third day the bread and flesh rose in the water, a sediment formed, and bubbles were observed mounting in the liquor. The mixture now possessed a vinous smell. This action was observed to continue about twice as long as in a similarly conducted experiment made without saliva. In the former case the fermentation was more gradual, and when complete the mixture possessed a pure acid flavour, and had no disagreeable smell. Notwithstanding that the subject has been laboriously investigated by some of the most ingenious experimenters of the day, the uses of the saliva in the economy are evidently still but imperfectly ascertained. Spallanzani was inclined to believe in a solvent action which this fluid was capable of exerting on animal matters, and thought that food, when inclosed in a tube perforated with numerous small holes, and placed in saliva, was more ra- pidly broken up and dissolved than when water only was used. The further observations of Berzelius and Miiller tended, how ever, to im- pugn the correctness of this opinion, pure water acting, according to their experiments, quite as efficiently as saliva. Some experiments have been made by Hiinefield, by which he thinks he has shown saliva to possess a peculiar action on fibrin : this, however, requires confirmation. In the year 1831 Leuchs made a most important discovery in connection with the history of saliva, viz., that when boiled starch is added to it, and the mixture is kept at a temperature of 98°, the starch becomes converted into sugar. This action has been since investi- gated by Mialhe, who attributes the pheno- menon to the presence of a peculiar proximate principle existing in saliva, to which he has given the name of animal diastase, in con- sequence of its possessing the qualities of that principle as it exists in the vegetable kingdom, in germinating seeds. In order to obtain this substance the saliva is to be fil- tered, and then precipitated by the addition of absolute alcohol, of which generally from five to six times the weight of the saliva are re- quired to effect the purpose. The animal diastase falls in the form of a flocculent pre- cipitate, which may be collected and dried on a filter. It forms about 0"2 of the whole saliva. It is a white substance, insoluble in alcohol. A series of experiments have been lately made by M. Bernard, with a view of deter- mining what the action of saliva may be in the digestive process. He first satisfied himself that the saliva of the horse and the dog, as well as that from the human subject, possessed the property of de- composing starch into sugar, under the con- ditions of temperature above described. The saliva of the dog, however, effected the con- version but slowly, that of the horse more quickly, but neither nearly with the rapidity of human saliva. The dog's saliva required nearly eight times as long as that from man, and that of the horse nearly four times as long. Care was taken in these experiments to employ the same quantities of saliva and of starch. Pure saliva, obtained from the parotid and submaxillary glands of the dog, were found by Bernard" quite incompetent to effect the transformation of starch. This agrees with the observation of Lassaigne, who found that pure saliva from the parotid of horses pos- sessed no transforming power of the kind, though mixed sahva taken from the oesophagus acted well on starch. According to Ber- nard's experiments, the explanation of this rests on the fact that the power of trans- formation is a property of the secretion from the mucous membrane lining the mouth, for on placing layers of that membrane in contact either with starch or sugar he obtained de- composition, and lactic acid was produced. He thus reduces the importance of saliva, as an adjunct in digestion, to little more than that of a lubricating fluid. Saliva of Animals . — The saliva of animals has not been much experimented upon. Berzelius remarks as follows on the saliva of the dog * : — " As obtained from the pa- rotid, it is a pale yellow fluid of mucila- ginous consistence, resembling white of egg in its physical characters. It leaves 2*58 per cent, of solid matters on evaporation. These solids form a transparent paie yellow varnish on the surface of the evaporating dish, which becomes moist by exposure to air. Alcohol extracts principally chlo- ride of sodium from this mass, and, by eva- porating the alcoholic solution, crystals of the chloride can be obtained nearly in a pure state, being, however, mixed with a small proportion of a yellowish substance, com- posed principally of lactate of soda and os- mazome. Sulphocyanogen cannot be de- tected with certainty in the alcoholic extract, and but a trace only of its reaction with the salts of iron can be observed. The portion of solid matter which is in- * Traite de Chimie, voL viL SALIVA. 419 soluble in alcohol contains salivary matter, combined with soda, and its reactions accord perfectly with those of the salivary matter found by Gnielin in human sahva. Phosphate of potash, phosphate of soda, and a small proportion of carbonate of lime, also exist in this saliva. The saliva of the sheep, according to Ber- zelius, is clear, and not adhesive, like that of the dog. It has a feeble saline taste, and a faint alkaline reaction. When dried, it leaves 1*68 per cent, of solid matter, which forms an opaque white membrane, and becomes moist by exposure. Chloride of sodium is extracted from this mass, in octahedral crystals, by di- gestion with alcohol. The salts of iron yield ample evidence of the presence of sulpho- cyanogen in the alcoholic solution. The por- tion of solid matter insoluble in alcohol, when treated with water, yields little else than salts. So completely is this the case, that the eva- porated aqueous solution scarcely gives out an empyreumatic odour while being heated to redness. The mass, which is insoluble both in water and alcohol, is brittle and mem- branous, insoluble in acetic acid, and not gelatinised when moistened by it. The acid, however, dissolves out {ihosphate of lime, after which it is precipitable by the addition either of ammonia or oxalate of lime, but not by in- fusion of galls. The following is an analysis of the saliva of the sheep : — Water 98*90 Matters soluble in alcohol (ex- tract of meat, a matter which crystallises chloride of sodium in octahedra, chloride of so- dium, and a small proportion of sulphocyanide of sodium) . O'll Matters soluble in water only (traces of ptyalin, a consider- able quantity of phosphate of soda and chloride of potassium, and carbonate of soda) - - 0*82 Matters insoluble in water and alcohol (mucus or coagulated albumen, and a small quantity of phosphate and carbonate of lime) 0*05 The pecuhar quality possessed by sahva of becoming mucilaginous and adherent, was at- tributed by Tiedemann and Gmelin to a solu- tion of mucus in alkaline carbonate. This last is present in the saliva of the sheep in such abundance, that when dry it effervesces on the addition of acids. The saliva of the dog, however, contains most, and the saliva of man the smallest quantity of the salt. Ac- cording to Tiedemann and Gmelin, the alkaline carbonate of human saliva is a potash salt, while the saliva of the dog and sheep contains carbonate of soda. The alkaline phosphate contained in saliva exists in larger proportion in tiiat of man, and of the sheep, than in that of the dog. All three contain chloride of sodium in large quantity. The sulphocyanide which exists in the saliva of man and of the sheep cannot be satisfactorily detected in the dog. Ptyalin is almost wanting in the saliva of the sheep, while that of the dog is deficient in animal extractive matter. Lassaigne and Leuret found the same quan- tity, viz. about one per cent, of solid matters, in the saliva of man, tlie horse, and the dog. The saliva of insects has been collected by Reuzzer*, but not in quantity to admit of analysis. It was found, however, to yield an alkaline reaction. SALIVA IN DISEASE. SaUvari/ Calculi. — As the result, in all pro- bability, of some defect in secretion, the sahva occasionally gives rise to the formation of calcu- lous matter. Thus, what is commonly called tartar, tends to deposit upon the teeth. Ber- zelius has examined this substance, and found that water extracted ptyalin from it, and that the remainder was soluble in hydrochloric acid, only a small residue composed of mucus being left unacted upon. Caustic ammonia precipitated phosphate of lime, and ammo- niaco-magnesian phosphate from the acid solution. Analysis yielded the following result : — Ptyalin 10 Salivary mucus - - - - 12*5 Earthy phosphates - - - 79-o Animal matter soluble in hydro- chloric acid - - - - 7*5 1000 Vauquelin and Langier found one of these masses to contain Water ----- 0 07 Salivary mucus insoluble in acids and in water - - - - 0*13 Phosphate of lime, with traces of magnesia - 0'66 Carbonate of lime - - - 0 09 Animal matter soluble in hydro- chloric acid - - - . 0*05 Salivary calculi only occasionally occur in the human subject, but are frequently ob- served in animals. One of these substances from the human subject yielded, according to the analysis of Poggiale, 94 per cent, of phos- phate of lime, the remainder being mucus and other animal matters. Wurzer found, in a concretion from the submaxillary gland of a man, carbonate of lime, earthy phosphates, oxide of iron, and manganese. Calculous concretions, obtained from the salivary ducts of the horse and ass, have been analysed by Lassaigne, Henry, and Caventon, with the following results : — * Physiol. Untersuch. iiber die tliierisclie Haus- haltimg' der lusecteu. Tub. 1817. E E 2 420 SALIVA. Caventon. Lassaigne. Henry. The Ass. The Horse. The Horse. Carbonate of lime - Carbonate of magnesia - Phosphate of lime - Animal mat- ter - Water - 91-6 4-8 3-6 84 3 3) 85-52 7-56 4-40 2-42 100-0 99 99-90 Ramda. — The disease called ranula, which was long supposed to depend upon the deten- tion of saliva within the salivary duct, owing to inflammatory closure of its orifice, and the dis- tention consequent upon such condition, has been lately shown by Dr. Goruss Besanez* to depend on the development of an encysted tumour within the duct. The fluid evacuated from ranula has been analysed by him, and its composition determined as follows : — Water - 95 -029 Traces of fat and chloride of sodium - 1-062 Aqueous extractive matter - 0-923 Albuminate of soda - - 2-986 This analysis shows the contained fluid of ranula to differ entirely from saliva, and places it among the products of morbid secreting sacs. Under the microscope, blood corpuscles and inflammatory exudation corpuscles were observed, none of the ordinary characters of saliva appearing. Much curious information has been collected by Dr. Wright with regard to the morbid conditions of saliva, and the production of hydrophobic disease. Among the statements made by various authors are the following, -j- Hydrophobia. — Ambrose Pare agrees v.ith Galen and Dioscorides in the opinion that morbid saliva may produce hydrophobia by contact with the second skin. The disease is stated by Coelius Aurelianus to have been com- municated to a sempstress who used her teeth to unsew the cloak of a hydrophobic patient. Schenckins states hydrophobia to have been communicated by a sword which had been used some years before for the purpose of destroying a rabid dog. Palmarius relates that a peasant rendered his children rabid by kissing them. jNIagendie and Breschet succeeded in pro- ducing hydrophobia in a dog by inserting the saliva of a rabid man under the skin of the animal. Dr. Herturch found that out of fifty- nine trials, only fourteen animals became affected with real rabies. ]Mr. Youatt suc- ceeded in causing hydrophobia in a healthy dog by inserting as a seton-cord a piece of * Heller's Archiv fiir Phvs. und Patholog. Che- mie und ISIikroskopie, vol. ii. t See Dr. Wright's communications to the Lancet, 1844. silk moistened in the mouth of a hydrophobic animal. There appears but little doubt that hydrophobia is really a disease produced by a morbid poison circulating in the system ; nor does the long period which occasionally elapses between inoculation and the develop- ment of the disease in anv way miUtate against the correctness of such a view, for we are aware, from the history of other well- recognised morbid poisons, how various the period required for development of action is; probably bearing some relation to the tempe- rament and general habits of the subject af- fected. Dr. Wright beheves that there is no che- mical difference (or, rather, none admitting of detection) between healthy saliva and that secretion which is capable of producing hy- drophobia. He has succeeded in producing rabies by injecting healthy saliva into the veins of animals, and it appears probable from his observations, that the difference between sahva capable of producing hydrophobia, and the fluid in its normal state, must be regarded rather as one of degree than in kind. Infection, — Saliva is said to have produced disease by contact in a variety of ways ; with how much truth appears most uncertain, but the following statements are related as mat- ters of fact : — Syphilis is said to have been communicated by kissing, and by the morbid saliva adhering to a drinking cup. Lassius, Wedehus. and Victor Schneider are of that opinion. Phthi- sis, according to Bernhard Gladbach, has been communicated by means of the saliva ; and scurvy, also, according to Rolfincius, Senner- tus, and Michael. Ledelius states that an old woman infected a boy with ague by giving him bread to eat which she had previously mumbled. ]Man\' other equally strange and disgusting statements of this kind have been put forth by old writers, which show httle else than the imperfect method of inquiry which satisfied the older investigators, and a lamentable inchnation on their part to re- gard coincidences as of necessity bearing the relation of cause and effect. The saliva is stated to become coloured occasionally, but the subject requires further investigation. Drs. Thomson and Christison have noticed it of a blue colour under the use of lead, and Dr. Wright says that ordinary medicinal doses will produce that effect. The same observer has noticed a deep blue co- loured saliva in purpura and advanced stages of fever, and is of opinion that prussian blue is the cause, but has not yet examined the point. Great acridity of saliva has been ob- served in maniacal patients. Dr. Wright has recorded that such saliva is sometimes so irritating as to be capable of excoriating the hand when applied to it. Children's saliva may become so acrid as to excoriate the nipples of any nurse who may suckle them. ^lercurial Salivation. — Simon has obtained acetic acid from sahva discharged during sali- vation, and believes it may also exist in rheu- SALIVA. 421 matism. Donne says the saliva becomes acid in many forms of disease. Brugnatelli found oxalic acid in the saliva of a phthisical patient. The following is Simon's analysis of the saliva of mercurial salivation (it contained acetic acid which was volatilised during evaporation) : Water 974-12 Yellow viscid fat - - - 6"94 Ptyalin, extractives, and traces'! ^.^^ of casein - " J Alcoholic extractives, and salts - 7'57 Albumen . - - - 7-77 This saliva, therefore, differed from that of health in containing excess of solid constitu- ents, arising from excess of fatty matter, ex- tractives, albumen, and salts. The ptyalin remains much as in health. L'Heritier gives the following as the mean of three analyses of the saliva in mercurial salivation. Water - - - 970-0 instead of 986-5 health. Organic matters 28-6 „ 12-6 Inorganic matters I'l „ ]-9 L'Heritier, like Simon, found no great va- riation in the amount of ptyalin. Dr. Wright found a great increase in the quantity of mucus contained in the saliva dur- ing mercurial salivation. He could not detect mercury in the secretion. His analysis is as follows : — Water 988' 7 Ptyalin ----- 1-9 Fatty acid - - - - 0-4 Albuminate of soda - - - 0*6 Mucus, with a trace of ptyalin - 3"8 Lactates ~| , i Phosphates I P^f^h I Hydrochlorates f f.^^^ f Hydrosulphocyanate J Gmelin found a considerable variety in the saliva of patients who had been salivated by mercurial inunction. In one case a large quantity of fat was detected by him. He obtained mercury from this saliva. Spontaneous Salivation. — The saliva of spontaneous salivation has been examined by Vogel, who found it constituted as follows : — Water - - - - 991-2 Ptyalin, osmazome, fat, and \ albumen - - - J Salts of soda, potash, and lime 4-4 This shows no great variation from the na- tural standard. Mitscherhch and Guibourt, who also ex- amined the saliva of spontaneous salivation, found no increase in the solid constituents, while the sulphocyanogen and ptyalin were deficient. Simon examined the saliva of a patient suf- fering from inflammation of the pancreas (?). It vvas a clear viscid fluid secreted in great abundance. It contained mucus, and was of alkaline reaction. Its specific gravity was 1005. Under the microscope, numerous oil ve- sicles were visible, besides ordinary mucus. globules, and epithelium scales ; 1000 parts of this saliva yielded 10 parts of solid matters. L'Heritier examined the saliva of chlorosis, and found it to suffer from watery degenera- tion, in the same manner as the animal tissues and secretions generally. In dropsy, with albuminous urine, the saliva was found by L'Heritier to contain. Water - - - 985-9 Organic matter - - 13*6 Inorganic matter - - '5 The amount of water contained in saliva appears to diminish in inflammatory affections. The following is a mean result obtained from six analyses made on the saliva of cases of in- flammatorj' fever, pneumonia, and erysipelas : Water - - - 968-9 Organic matters - - 30-0 Inorganic matters - I'l The proportion of ptyalin was found in- creased. Scherer analysed the saliva of a girl suffer- ing from a scorbutic affection of the mouth. There was a large secretion, forty ounces flow- ing in the twenty -four hours. It was fetid and alkaline, and of specific gravity 1004. Analysis yielded the following result : — Water - - - - 988 '8 Casein - 6*5 Fat 0-6 Extractive matter and ptyalin 1*8 Carbonate of soda - - 1-2 Chloride of sodium - - O'T Phosphate of lime - - 0'4 Confervoid growths and infusoria were de- tected in this saliva as taken fresh from the patient. A specimen of saliva from a phthisical pa- tient was examined by Landerer*, who found it to contain a great number of small fat glo- bules aggregated into a viscid mass. These globules exhibited the properties of oleic acid. Several kinds of diseased saliva have been analysed by Dr. Wright, and I shall subjoin his analyses. 987-4 -7 3-9 FATTY SALIVA. Water - - - - Ptyalin - Adventitious fatty matter and fatty acid - Albuminate of soda - - - 1*5 Sulphocyanide of potassium - a trace Mucus 2-4 Lactates - f potash "j Hydrochlorates - \ soda - 1*8 Phosphates - \\\me J SWEET SALIVA. Water 986*9 Ptyalin ----- "3 Fatty acid - - - - -2 Muco-saccharine matter - - 5-6 Albuminate of soda - - - -4 Sulphocyanogen - - - a trace * Heller's Archiv. 1846, p. 297. E E 3 422 SALIVARY GLANDS. Mucus, with trace of ptyalin - 2'6 Lactates - ( potash 1 Hydrochlorates - - - 1-7 Phosphates - lime J Loss - 2-3 MILKY SALIVA. This kind of saliva has been noticed by several authors, A case is related by Nuck in which, during four months, milky saliva was secreted by a woman who became gravid dur- ing lactation. When the flow of milky saliva commenced, an intumescence of the breast was observed to decline. Richard, speaking of milk fever (Ann. Clin, de Montpellier), says the malady occasionally terminates favourably by the occurrence of a salivation consisting of milky saliva. Other authors also have noticed the occurrence of milky saliva, in connection with a suppressed flow of milk from the mammary gland. Dr. Wright describes milky saliva as white, completely opaque, neutral to test paper, and rendered curdy by acetic acid. URINARY SALIVA. This variety of saliva has been described by Dr. Prout. The salivation occurred spon- taneously. The patient suffered anorexia, and was weak, but otherwise healthy. The renal secretion was diminished, and the saliva had a urinous taste- It was opalescent, foamed when agitated, and was slightly ropy. Its specific gravity was 1005. It restored the blue colour to reddened litmus paper. The soluble salts of lead, mercury, and silver, caused precipitates when added to it, as did also the mineral acids. Dilute acetic acid caused a precipitate, but no further precipitate could be obtained by subsequent addition of a solution of ferrocyanide of potassium. There- fore no albumen was present. 1000 grains of this saliva, when evaporated to dryness at a temperature between 212° and 300°, left 8*65 grains, which were composed as follows : — Animal matter peculiar to saliva - 3'33 Alcoholic extract, apparently! similar to that from the blood J Sulphuric acid - - - - 0"90 Hydrochloric acid - . . 0*75 Phosphoric acid - - - - 0*06 Alkali — partly potash and partly 1 o.kk soda J 2_ 8-65 In this case, when the urinary secretion was restored by the use of diuretics, the sa- livary discharge was proportionally diminished. (G. Owoi Rces.} THE SALIVARY GLANDS (Les Glandes Salivaires, Fr. : Die Spcichel-Drusen^ Germ. ; Le Glandule Salivali, Ital.). A series of conglomerate glands, arranged in a curved manner, and following the circumfe- rence of the inferior maxilla from the posterior border of one side to that of the other, and pouring their secretion into the mouth by means of excretory ducts, are thus denomi- nated. They present a distinctly lobulated granular appearance, the component lobes and lobules being more or less loosely connected together by areolar tissue derived from the surface, and which, though serving the pur- pose of an investing membrane, is not of a sufficiently definite character to constitute a distinct capsule. They have a yellowish or greyish-red appearance, and are thus at once distinguished from the soft structures with which they are in immediate connection, namely, the cellular membrane and the lym- phatic glands, the former being perfectly white, and the latter pale brown. They are three in number on either side, and are named from above downwards the Parotid, Submaxillar}', and Sublingual, and have in the same direction a relation as to their size, the parotid having the largest, the sublingual the smallest, and the submaxillary an intermediate volume. Though usually se- parated from each other by a slight interval. SALIVARY GLANDS. 423 they not un frequently impinge the one upon the other, the lower edge of the parotid ap- pearing to be structurally connected with the posterior border of the submaxillary, and the latter forming a junction with the sublingual. An uninterrupted glandular chain then in these instances surrounds the lower jaw. The saliva secreted by them is poured by the ducts of the two last into the floor of the mouth, and by the duct of the first into the posterior part of the side of the cavity between the cheek and the upper and lower dentar arches. The Parotid Gland is so named from its si- tuation in the immediate vicinity of the exter- nal ear {japa. near, and olc the' ear). It fills up the space of the same name, and is conse- quently bounded in front by the posterior edge of the ramus of the lower jaw, behind by the meatus auditorius externus above, and the mastoid process, digastric and sterno-mastoid muscles below : internally by the styloid pro- cess and muscles attached to it, together with the internal and external pterygoid muscles : superiorly by the posterior or parotidean divi- sion of the glenoid cavity within, and the zygomatic process without : inferiorly by a line continued on a level with the lower bor- der of the horizontal ramus of the jaw from its angle to the anterior border of the sterno- mastoid muscle. The dimensions and form of the gland can only be well ascertained after re- moving it from its various connections, and in so doing it will be found that its posterior surface adheres very strongly by condensed cellular membrane to the cartilaginous portion of the meatus auditorius externus, while from its inner edge will be observed a process ex- tending between the styloid muscles and the internal pterygoid as far as the pharvnx. A dense fibrous septum, the stylo-maxillary, con- stituting one of the fixed points of attachment of the deep cervical fascia, separates it usually from the submaxillary gland. It has a triangu- lar or pyramidal form. "The base, which is su- perficial and slightly convex, rej^resents its ex- ternal surface, and is covered over bv a dense areolar tissue, known as the parofid fascia,'' from which the different processes which sepa- rate the component parts of the gland are ob- served to proceed. The apex is^the deepest- seated portion of the gland, and is represented by the prolongation already alluded to. The gland is bent, as it were, upon itself from be- hind forwards, so that its anterior surface presents a deep vertical groove, corresponding with the convexity of the ramus of the jaw, which is consequently overlapped bv it ex- ternally and internally, in the former situation extending to a greater or less degree over the masseter, in "the latter over the internal pterygoid muscle, and stylo-maxillary liga- ment. The part overlapping the masseler externally gives off above a process which runs between the zygoma and the duct of the gland, is horizontal in direction, and some- what triangular in form, and is known as the Accessory Parotid Gland or " Soda Parotidis:' It varies as to size, extent, and relation with the gland itself. It is ordinarily about two- thirds of an inch in length, a third of an inch in the longest part of its vertical diameter, and from one- sixth to one-eighth of an inch in thickness. It is generally, as it were, an offset from the body of the gland, and has no imme- diate connection with Steno's duct : at other times it is distinct from the body of the gland, and opens by one or more excretory ducts into, this canal. It occasionally becomes hyper- trophied when the body of the parotid itself is atrophied. Cruveilhier has observed two small accessory glands, one at the middle and the other at the anterior part of the masseter muscle. The parotid measures in a vertical direction from an inch and a half to two inches, from before backwards from an inch and a quarter to an inch and a half, and from with- out inwards about an inch. The lobes which enter into its composition are irregularly rounded, and considerably smaller than those of the submaxillary gland. They range from the one-eighth to the one-fifth of an inch in diameter; and these again are constituted of lobules having an average diameter of about the ^ of an inch, the smallest measuring .j-i^, and the largest about 3^ inch across. The relations of the external carotid artery, and its terminal branches, the external jugular vein, the facial and the anterior auricular nerve, and the further relative anatomy of the gland, have been already fully entered into.* We may mention, however, that in the sub- stance of the parotid, i. e. in the cellular tis- sue between its lobules a little below the surface, are embedded one or more lymphatic glands which can at a glance be recognised from the structure of the parotid by their brown colour; smooth surface, and compara- tive density. These glands not unfrequently undergo morbid changes, and by their gradual enlargement cause progressive atrophy of the parotid itself, and ultimately assume its ana- tomical position. This circumstance consti- tutes therefore an important element in the inquii-y as to the nature of any morbid growth occupying the parotid space, but which it would be out of place here further to allude to. The Duct of the Parotid Gland, called also the Duct of Steno, emerges from above the middle of its anterior border, accompanied by several branches of the portio dura, runs hori- zontally forwards across the masseter muscle as far as its buccal border, passing about half an inch below the zygoma, and immediatelv below the accessory gland and transverse facial artery. Having reached the anterior border of the masseter, it curves over a mass of fat between it and the buccinator ; forming then a very obtuse angle, it perforates the latter, and glides between it and the mucous mem- brane of the mouth, which it perforates oppo- site the second upper molar tooth. This terminal oblique portion is about the fifth of an inch in extent, and has justly been compared by Cruveilhier to the vesical portion of the ureter, w hich, after having perforated * See Parotid Regiox. E E 4 424 SALIVARY GLANDS. the muscular tunic of the bladder, runs for the extent of an inch between it and the mucous membrane. The parotid duct is from two and a half to three inches in length, and is covered over by a prolongation of the areolar tissue which forms the investment of the body of the gland. This can be distinctly traced as far as the point at which it perforates the buccinator, and here it is surrounded by an aponeurotic expansion derived from the tendon of that muscle, and by a series of glands continuous with the genial glands, the ducts of which open partly into it and partly into the mouth. Having removed the external cellular covering of the duct, its true middle or fibrous coat is observed, giving it a distinct opaque white appearance. It is strong, dense, and elastic. Its thinnest portion is over the oblique part of the duct that glides between the muscular and mucous lining of the buccal cavity, its thickest that covering that part of it between the buccinator and the masseter, the remainder of the duct having this coat developed to an intermediate extent. Beneath the middle coat is the mucous lining, the cylindrical epithelium of which commences, according to Henle, suddenl^y at the excretory orifice, and con- tinues as far as the delicate divisions of the duct in the substance of the gland. The cells of this epithelium in the main duct range from the y^Vo to the -g-i^- part of an inch in their long diameter. The parotid derives its arterial supply from the main trunk of the external carotid, the supeificial temporal, transverse facial, anterior ami posterior auricular : its venous, from ves- sels of the same name. The lymphatics ter- minate in the superficial and deep facial and cervical glands. The nerves are derived from the facial, the anterior auricular, and the ex- ternul carotid plexus. The Submaxillary gland, much smaller than the parotid and larger than the sublingual, is situated in the anterior portion of the digas- tric space. It is irregularly oblong in form, and is enclosed in a loose investment of areolar tissue more delicate than that cover- ing the parotid. Its long axis is directed from before backwards, and is about an inch and a half in extent. Its external or maxil- lary surface is slightly concave, is lodged in a groove in the bone, and is in immediate contact with the mylo-hyoid nerve. The inferior or platysmal surface is in relation with the platysma-myoides and superficial cervical fascia, constituting, in fact, that part of the gland which is seen on reflecting that muscle. The internal surface, which looks slightly upwards, is in relation with the pos- terior third of the mylo-hyoid muscle, the tendon of the digastric, and the stylo-hyoid and stylo-glossus. The anterior extremity, which is smaller than the posterior, impinges on the anterior belly of the digastric. The posterior border is deeply grooved by the facial artery and vein, which are occasionally sur- rounded entirely by the structure of the gland. From the narrowest portion of the gland, which would be represented by the confluence of the inner and outer surfaces above, gene- rally proceeds a process, longer than the gland itself, and passing along the upper surface of the mylo-hyoid muscle in company with the excretory duct, but above it, as far as the sublmgual gland in front, with which it is oc- casionally incorporated. This process may be regarded as analogous to the accessory gland of the parotid, and like it varies con- siderably in size and relation to the body of the gland. In a subject recently examined, we found it represented by two accessory glands, the upper or larger being about the size of a horse-bean, embracing the poste- rior half of the lower border of the sublin- gual gland, and grooved behind by the trunk of the gustatory nerve. It opened by a dis- tinct duct, more than half an inch in length, into the main canal about the middle of its upper border : the other accessory gland, very small, situate half an inch further back, and also communicating with the lower border of the main duct by a canal one-sixth of an inch long. The primary lobes of the submaxillary gland are much larger than those of the paro- tid, and the lobules have an irregularly trian- gular arrangement. A quarter of an inch below the part at which the accessory process is ordinarih- given off, appears the commencement of the excre- tory canal, or Wharton's duct, winding behind the'posterior border of the mylo-hyoid muscle. It first lies below the gustatory nerve l)etween it and the lingual, and after a course of a quarter of an inch, crosses the former at an acute angle, and again gets below it, resting on the hyo-glo3sus muscle. It accompanies the gustatory towards the tip of the tongue be- tween the sublingual gland and the genio- hyo-glossus muscle to the side of the frasnum lingua, N\here it terminates. In the terminal part of its course it is directed forward, lies immediately beneath the mucous membrane, and opens by a very narrow orifice into the mouth, in the centre of a papilla of mucous membrane. This papilla forms an obvious prominence by the side of the freenum linguae, and is situated above the eminence formed by the anterior part of the upper edge of the sublingual gland, behind the incisor teeth. The duct is about two inches in length, its coats much more delicate, and consequently more extensible, than those of the parotid. Its calibre exceeds that of the parotid duct, and, like it, its narrowest portion is that im- mediately beneath the mucous membrane, and this gradually contracts more and more, so that the terminal orifice becomes so small as scarcely to be visible by the naked eye. The arteries and veins that supply the submaxillary gland, are derived from the facial and lingual. The nerves are from the mylo-hyoid branch of the dental, and the gustatory, but chiefly from the submaxillary ganglion. The lymphatics communicate with the deep cervical glands. The Sublingual gland forms a distinct eminence underneath the anterior part of the tongue by the side of the fraenum. It SALIVARY GLANDS. 425 can be felt in the floor of the mouth, and forms a prominent ridge which elevates the mucous membrane. Its long axis is from before backwards, following, in fact, the di- rection of the horizontal ramus of the jaw, to which the gland is appHed. The inferior sur- face rests upon the mylo-hyoid muscle ; the external is received into the sublingual fossa ; the internal is in relation with the genio- hyo-glossus and hyo-glossus below, and the mucous membrane above, the upper edge being covered by the latter. It is shaped somewhat hke an almond, flattened from side to side, having its large extremity anteriorly. It is more compact in front than behind, in which latter situation its component lobes are occasionally separated the one from the other, and exist under the form of distinct irregularly rounded glands, with separate ex- cretory ducts about a quarter of an inch in length, coming from their upper surface. The sublingual gland is from one inch and a half to two inches in its long axis, three quarters of an inch in the longest part of its vertical diameter, and about a quarter of an inch from side to side. It has a more granular feel, and its lobules, which are mutually connected by a very delicate areolar tissue, are more dis- tinct, harder, and smaller than in either the submaxillary or parotid. The ducts of the sublingual are very nume- rous, and their orifices can be seen without much difficulty, opening into the floor of the mouth, behind the movable papilla of Whar- ton's duct, and along the crest of mucous membrane which is elevated by the upper border of the gland from which they take their origin. They are extremely thin and delicate, and pour out, when pressure is made on the body of the gland, a distinctly viscid saUva. They range from one-tenth to one- third of an inch in length, vary much in their direction and relative situation, and are in number from 7 to lo. The anterior are ver}' short, curve slightly on themselves from behind forwards, are about four or five in number, and some of them, according to many anatomists, form a conununication with Whar- ton's duct, the remainder piercing the mucous membrane of the mouth. The ducts from the middle and posterior part of the gland arise at unequal intervals from each other, run in a parallel, divergent, or convergent direction, and pierce the mucous membrane by straight orifices, the posterior two or three not being longer than the one-tenth or one- eighth of an inch. They are known under the name of the Ducts of Rivinus. Bartholi- nus* has described another duct in connection with the sublingual gland, and which some- times proceeds from the accessory gland of the submaxillary. It rims parallel to Whar- ton's duct, and pierces the mucous membrane by the side of it. It frequently opens, how- ever, into Wharton's duct, and both terminate by a common mouth. It is by no means * Caspar! Bartholin. Thorn, fil. decluctu Salivali hactenus non descripto Observatio Anatomic a. 1G84. usually met with. In a young male, whose salivary glands we recently dissected, the duct of Bar'tholinus was very distinct (a ci,fig. 139). Fig. 304. a a, the dncts of Bartholinus ; hb, the ducts of Wharton ; c c, the inner surface of the sublingual gland ; d, inferior surface of the tongue. It arose from a large lobe at the upper third of the internal surface of the sublingual gland, midway between its anterior and posterior extremity. It was nearly equal in calibre to the duct of Wharton, and was more than half an inch in length, and opened on the left side close to the orifice of that duct in the centre of the loose papilla of mucous membrane. The two orifices were so closely approximated that it was difficult to determine their indi- vidual identity. The duct of Bartholinus of the right sublingual, on the other hand, al- though arising from the corresponding part of the body of the gland, and being of the same length and cahbre, opened at the anterior part of the crest of the mucous membrane, the one-eighth of an inch behind the orifice of Wharton's duct. The sublingual gland derives its arterial suppl}' from the sublingual branch of the lin- gual, and the submental. Its nerves are de- rived from the gustatory branch of the fifth. Its lymphatics communicate with the deep cervical glands. The salivary glands, according to the re- searches of Huschke, are more voluminous, in proportion to the bulk of the body, in the infant than the adult, the submaxillary and sublingual, however, being proportionately larger than the parotid. In the adult, on the other hand, the parotid is, in proportion to the bulk of the body, larger than the other two. The subsidiary salivurij glands. — The labial, buccal, molar, palatine, posterior, and interior lingual glands may without any impropriety be reckoned among the glands of the salivary apparatus, being identical in their structure, and provided with excretory ducts opening on to the free surface of the mucous mem- brane. Varying materially in size, and irre- gularly rounded or flattened, they exude a 426 SALIVARY GLANDS. slightly viscid saliva by their orifices, which are visible to the unassisted eye. We have already stated that the posterior part of the sublingual gland is occasionally represented by one or more distinct glands in juxta-position, each furnished with a very short excretory duct. These distinct lobes of the gland are in every way analogous to one of the molar glands or larger labial. It will thus be observed that the transition of the primary to the subsidiary glands is by no means rapid, but that they run the one into the other by insensible gradations, the sub- lingual gland passing from the one series into the other. A molar, labial, or buccal gland, with its excretory duct, might then be not inaptly compared, according to its size, to a secondary or tertiary lobule of the parotid, or submaxillary. The labial glands form a series of closely packed small spheroidal glands, of consider- able density, situated in the areolar tissue between the mucous membrane of the mouth and the orbicularis oris muscle, and in relation above and below, consequently, with the upper and lower lip. They are not of uniform volume or number. Sebastian* has observed as many as fifty-seven in the lower lip, and in other instances from thirteen to twenty- one, their size increasing in the inverse ratio to their number. They are more nu- merous in the infant than in the adult. Their excretory ducts open perpendicularly or ob- liquely into the vestibule of the mouth on the posterior or free surface of the labial mucous membrane. They are not visible to the eye when the lips are in their natural lax position, but when the latter are everted, so that the mucous membrane is rendered tense, they form considerable projections. The buccal glands are exactly analogous to the labial glands in form and position, being irregularly spheroidal, and placed between the buccinator and mucous membrane, and open by the orifices of distinct ducts on to the free surface of the latter. They are, however, smaller. The molar glands — two, three, or four in number — form an exception as regards their situation to the above glands, being placed between the buccinator and masseter muscles. They are also larger and more dense, being composed of several lobes. The ducts ter- minate by opening on to the mucous mem- brane at the posterior part of the cheek. In a subject we recently examined, their ter- minal orifices were arranged horizontally at unequal distances from each other, on a level with the orifice of Steno's duct, but more than half an inch behind it. They were five in number. We have not succeeded in observ- ing the communications which the ducts of one or more of these glands is stated by some anatomists to estabhsh with the duct of the parotid. The 'palatine glands are very numerous and * Sebastian, Reclierclies sur les Glandes Labiales, Annales de la Chirurgie. Paris, 1842. t. vi. small, and situated partly between the mucous membrane and the palatine arch, and partly between the mucous and muscular layers of the soft palate. The former are situated on either side of the median line, and form a thick layer, being more closely aggregated together in the front and behind than in the middle, opening on to the mucous membrane by distinct orifices. The latter, smaller than the former, exist both on the upper and lower surface of the velum, and are continuous below, where they are more numerous than above, with the glands of the hard palate. The posterior lingual glands are placed at the back part of the tongue, directly behind the large papillae, which form a distinct pro- minence at this part. They are spheroidal, and have remarkably short excretory ducts, the circular orifices of which, however, are distinctly visible. The last glands to which we would direct attention are two in number, and from their situation may be appropriately termed the anterior lingual glands. They have been re- cently described by Blandin, Nuhn*, and Schlemm, as being situate below the apex of the tongue, between the lower longitudinal and transverse muscular fibres, and pouring their secretion during the movements of that organ on to the mucous membrane beneath the tip. They have only as yet been disco- vered in man and the ouran-outan. We have observed them on the inferior surface of the tongue, half an inch behind its anterior border, immediately above the longitudinal muscular fibres, one on either side of the median line, and about two-thirds of an inch long. Broad behind and narrow in front, they are separated from each other in the former direction by an interval of about half an inch, in the latter are almost in mutual contact. Their direction therefore is obliquely from behind forwards and inwards {Jig. 305, b). Each gland is fur- Fig. 305. a. Bristles in the orifices of the ducts of the left anterior lingual gland, b. The right anterior lin- gual gland, c. The raphe of the tongue. nished with three or four delicate ducts, given off from its lower surface, and which perforate the mucous membrane obliquely parallel to the long axis of the gland 305, a). These glands are of less consistence than the molar or labial. We have met with one instance in * A. Nuhn, iiber eine bis jetzt noch nicht naiher beschriebene Drtise im Innern der Zungenspitze. Mannheim, 1845, quoted by Valentin in Physiologic der Menschen, 1847, zweite Auflage. SALIVARY GLANDS. 427 which only one gland was present, running at right angles to the middle line. It was convex in front and concave behind, having a trans- verse diameter of one-third of an inch, an antero-posterior one-eighth of an inch. It gave off three delicate ducts. The minute structure of the glands in general has been already fully inquired into *, and to the type on which they are formed the salivary glands offer no exception. A simple caecal membranous prolongation is the model to which they can all be referred, however complex each individual series of glands may appear. This grand generalisation, by which the ex- treme simplicity of the operations of nature is remarkably illustrated, has mainly been the result of a minute inquiry into developmental and comparative anatomy. We are particu- larly indebted, however, to Miiller and E. H. Weber for the exposition of the evolution and minute structure of the salivary glands. Miiller thus describes the first appearance of a salivary gland in Mammalia, and his ob- servations were taken from the embryo of a sheep, two inches long : — Its form is that of a simple canal with bud-like processes, lying in a gelatinous nidus or blastema, and com- municating with the cavity of the mouth. As the development of the gland advances, the canal becomes more and more ramified, in- creasing at the expense of the germinal mass or *' blastema," in which it is still enclosed. The blastema soon acquires a lobulated form, corresponding to that of the future gland, and is at last wholly absorbed. Yalentint remarks that a portion of this blastema, which contains nuclei and cell-formations, and which is not converted into glandular structure, is changed into blood-vessels, nerves, and connecting cellular tissue; and he has, further, accu- rately determined that the secondary tubes are formed independent of the primary, at the expense of portions of the blastema, in the vicinity of the main duct, with which, by a centripetal development, they ultimately com- municate. Thus, in the first stage of their development, the salivary ducts can be seen to constitute an independent closed system of tubes. The investigations of E. Weber i carry us a step further in the inquiry. He found, by a successful injection of the parotid in a human foetus, that the excretory duct, after having undergone its ultimate state of subdivision, by an extensive ramification of its secondary tubes, terminated in microscopic twigs, each twig having appended to it one or more minute cells or vesicles, forming small group-like lobules or bunches. These cells have not a uniform size, their long diameter, which is more or less in a line with the axis of each of the terminal divisions of the duct with which the cells are structurally conti- nuous, is, on the average, almost of a * Yide Article Gla>t). t Wagner's Haudworterbuch der Physiologie, Article Geavebe. X Meckel's Archiv. fur Anatomie et Physiologie, 1827. Paris line. Gerber * states these vesicles or cells are variously shaped, from to -j-i-g- of a Paris line in diameter, and upon the periphery of the gland appear mutually to compress each other and to become poly- hedral in their outline. They are united to- gether into small lobules, from four to seven times greater than each individual vesicle, the latter consequently being almost three times, the former about twelve times the diameter of the capillary blood-vessels which ramify on the surface. They form, in fact, the caecal terminations of the branches of the excretory tubes, without having of necessity an indi- vidual narrow connecting pedicle, as figured by Berresf in the minute anatomy o( the parotid. Such, then, is the essential structure of the salivary glands ; and in the full state of or- ganisation of each we recognise the elements of a mucous membrane, constituting the in- ternal lining of the excretory duct and conti- nuing throughout the series of its ultimate ramifications as far as the terminal vesicles ; a middle elastic coat, and an external covering of areolar tissue. The mucous membrane consists of an epithelial layer, and a basement membrane. The epithelium is of the co- lumnar variety, and maintains this character along the track of the excretory duct as far as its delicate divisions, where it gradually changes its character, so that that lining the interior of the vesicles is of the pavement tvpe. This transition of columnar into pavement epithehum would appear gradual; so that it is difficult to determine the point at which the one form terminates and the other commences. The basement membrane is continued alons the entire track of the tubular ramifications^ as far as the vesicles, the form of which it would appear to determine. There can be little doubt that this is the membrane which Berres alludes to as the proper wall of the vesicles, and describes as a small transparent membrane, covered over with molecules, and which also has been represented by Henle as homogeneous, but which he at the same time considers as composed of filaments of cellular tissue solidly united together.^ Considerable difference of opinion has ex- isted as to the nature of the middle coat of the glandular tubes, according as the largest or smallest have been examined. Yalentin re- marks that in the first case it has been considered fibrous, in the second simply horaoseneous. In by far the greater number of the terminal extre- mities of the glandular tubes the intermediate membrane appears clear and transparent, and gives neither in the fresh state, nor when re- agents are applied, any indication of a fibrous character. In all the large tubes the intermediate coat is formed of distinct fiat fibres, together with the characteristic fibres of cellular tissue, * Gerber, General and Minute Anatomv of Man and the Mammalia, translated by E. Gulliver, 1842. t Anatomia Microscopica Corporis Huraani, tab. ix. fig. 2. X Miiller 's Archiv. 1838, p. 105. 428 SALIVARY GLANDS. studded at intervals with elongated or rounded nuclei, which present a great analogy w'ith the fibres of organic muscle, if they be not completely identical witli it. We are at pre- sent, however, in doubt as to whether the intermediate membrane of small glands, and of the terminal portion of the large, be really a simple transparent membrane, or whether it acquire, as the tubes which it envelopes en- large, cellular and muscular fibres externally, whilst the previously transparent membrane disappears or remains as a basement mem- brane towards the epithelium ; or whether a separation or splitting of the transparent membrane into fibres takes place. In the opinion of Henle, all the true glands having a vesicular termination, from the smallest to the most complicated, have an intermediate mus- cular tunic, with a series of longitudinal fibres situated within, and circular fibres without, the former being much more highly developed than the latter, and entirely absent in the more delicate ramifications of the duct. Miiller, admitting the great difficulty of determining by the microscope the muscular character of the intermediate coat, is nevertheless of opinion that such is its nature, and appears inclined to believe that the frequent sudden expulsion of the saliva is attributable to it. The cellular or areolar tissue forms an in- tricate network throughout the whole struc- ture of the saUvary glands, and can be dis- tinctly traced to proceed along the course of the duct and its primary, secondary, and ulti- mate subdivisions. It unites together, more or less firmly, the different lobes and lobules, ultimately expanding over the primary aggre- gations of the vesicles of the gland, where it is lost to observation, not appearing to extend between each individual vesicle. The spaces, then, between the lobes and lobules are filled up with areolar tissue, which forms a kind of rete for the ramifications of the arteries, veins, and nerves. The vascular sujipJy. — This is derived from Fig. 306. Capillaries of Parotid of Pig. small branches which penetrate the areolar tissue at different points of the surface, and are conducted, as it were, by this tissue through the interlobular spaces as far as the primary aggregations of the vesicles, where they form a network, which is distributed over the elementary parts of the gland, as seen in ^g. 306, the vascular arrangement in the parotid of a pig, from a preparation of Mr. Quekett's, and in which the capillary vessels range from the -^^n to ttho of an inch. The nervous supj)li/. — The nerves are de- rived partly from the cerebro-spinal, and partly from the sympathetic system, and form a plexus around the arteries, which is ulti- mately lost in the interior of the gland. Their exact distribution, however, has not yet been accurately determined. The arrangement and course of the lym- phalics have yet to be made the subject of investigation. The salivary glands are particularly called into play during mastication ; and in order clearly to understand their relative import- ance, it will be necessary briefly to consider the nature of that process. The food having been taken into the mouth, is, in the first instance, coarsely divided by the incisor teeth ; and this divi- sion takes place by the alternate elevation and depression of the lower upon the upper jaw. This having been accomplished, the food is next submitted to the action of the molars, reaching the back part of the dentar arches, where the rotatory or grinding movement, brought about by the pterygoid muscles, is peculiarly exerted. Here its ultimate mechanical reduction and intimate admixture with the saliva from the parotid takes place in the following manner : — By the elevation of the jaw and the rotatory move- ment of the above muscles, it is alternately passed from between the two sets of teeth to between the latter and the cheeks on the one hand, and the tongue on the other. The buccinator contracting, urges it again between the two sets of teeth, from which it passes between them and the tongue, and is pushed, by the contraction of the muscles of that organ, again to its original position, between the den- tar arches. These different movements are alternately kept up until the entire mass of food has assumed its requisite state of me- chanical reduction, and during them the saliva flows down from the orifice of Steno's duct, becoming intimately incorporated with it, and aiding most materially in its integral sub- division. It is worthy of remark, that the position of the terminal portion of Steno's duct, or rather that part of it which passes between the fibres of the buccinator muscle, is such that it must be pressed upon during the contraction of the muscle at that parti- cular time when by the same action the food would be placed between the two sets of molar teeth, and the saliva not be immediately required. During the relaxation of the buc- cinator, on the contrary, and when the food SALIVARY GLANDS. 429 would be situated between the cheek and the teeth, the quantity of sahva amassed in the canal of the duct, by its temporary oblitera- tion, would flow down and become intimately mixed up with the particles of the food, v.'hich would now entirely surround its orifice. This relation, then, of the buccinator with the duct of the parotid would seem to regulate the supply of saliva, which, if this view be correct, flows down only at a time when it can be most thoroughly incorporated with the material during its mastication. The relation of the ducts of the submaxillary and sublingual glands to this process would seem to be of far less importance. The orifices of Wharton's ducts and the subhngual ducts situated behind the incisor teeth, would appear to hold a direct relation only to the primary stage of mastication, that is to say, lubricating with the saliva the larger masses into which the food is broken up during that process, and probably after its completion, immediately prior to the passage of the whole mass into the stomach. The position, then, of the duct of the parotid, which is so situated that mechanical means are brought into play, in order to insure the thorough incorporation of its saliva with the food, and the great comparative size of the gland itself, lead naturally to the in- ference that the parotid is by far the most important gland in the series, the submaxillary and lingual having but a subordinate function. This deduction has been experimentally proved by Bernard*, who, having made an aperture at the lower part of the oesophagus of a horse, administered to the animal about sixteen ounces of oats. Fifteen or sixteen seconds after the commencement of mastication, a rounded mass made its appearance at the oesophageal opening, well triturated, perfectly moist, pasty in the interior, and covered on the exterior by a moderately thick layer of tenacious mucus and saliva. A fresh quantity of the oats, in a similar condition, was pro- jected every three-quarters of a minute. At the end of nine minutes, the mastication of the entire quantity having been finished, the ducts of the parotid were divided, so that the saliva that was secreted could be conducted out of the mouth. The same quantity of oats was again given to the animal. In this second experiment mastication did not appear to be attended with any particular incon- venience, and was performed as easily as in the first. It M'as exerted, however, a much longer time ; for a minute and a half elapsed before the first mass made its appearance at the opening : this, though well triturated, and covered on its external surface with nuich mucus, was considerably smaller than those masses which had escaped from the oesopha- geal opening prior to the division of the ducts of the parotid. The interior of the mass, also, instead of being, hke them, well mois- tened and pasty, had but slight tenacity, and * Memoires siir le Role de la Salive dans les Phe- nomcnes de la Digestion. Archives Gendrales de Medicine, Janvier, 1847. was comparatively dry. Mastication and deglu- tition now became more and more difficult, lengthened, and laborious, so that an interval of from two minutes and a half to three minutes frequently occurred between the exit from the oesophagus of the successive masses. The horse, in its endeavours to swallow the oats which appeared to adhere to the palate, frequently gulped down a quantity of air, which escaped with noise from the oesophagus prior to the exit of the oats that had with such difficulty passed into the canal. At the end of twenty-five minutes, but little more than eleven ounces of the oats had been mas- ticated and swallowed, whereas, prior to the division of the parotid ducts, sixteen ounces had been well triturated and swallowed in nine minutes. Bernard further remarks, that he collected during the second experiment the sahva that flowed from the parotid ducts, and he found that it came away in an almost continued current ; but that during the time that he administered water to the animal not a single drop of saliva escaped. The circum- stance of the smallness of the masses passed in the second experiment, and the dryness of their interior, taken together with their ex- terior envelope of tenacious mucus and saliva, which was as abundant as before the division of Steno's ducts, lead to the inference that the former condition was owing to the absence of the aqueous secretion of the parotid ; the latter condition, to the fact of the submaxillary and sublingual glands being mainly engaged in the secretion of a tenacious saliva. Further experiments bring about the conclusion that the fluid from the parotid on the one hand, and from the submaxillary and sublingual on the other, are regulated by conditions special to each. Thus, the quantity of saliva secreted by the parotid of a horse is in direct ratio to the dryness of the food and the difficulty experienced in its mechanical division. The mastication of straw and hay causes the flow of more than that of oats and farinaceous matters ; the mastication of moist forms of food, hardly any. This, however, is by no means the case with the saliva from' the sublingual and the submaxillary ducts. This always flows nearly in equal abundance whether mastication be exerted on dry or moist forms of food, and, owning to its com- parative tenacity, is not easily imbibed into the centre of the masticated material, but gathers round the surface of the mass, thus favouring its passage along the alimentary canal. In a mechanical point of view, then, there are two forms of saliva : the one clear and aqueous, secreted from the parotid, and which may be denominated the "saliva of masticntioji" because its secretion is directly related to this act ; the other tenacious and secreted by the submaxillary and sublingual, " t/ie saliva of deglutition,'' because it always lubricates the surface of the alimentary mass, whether it be submitted to mastication or not. The above views of Bernard are materially strengthened by the fact of the high develop- ment of the parotid in animals that masticate, 430 SALIVARY GLANDS. and its absence or mere rudimentary condition in those that swallow -without masticating. Its comparative smallness, in relation to the submaxillar}' and sublingual in the human in- fant, is also corroborative. Without entering into the physiology of the secretion of the saliva, which will be found treated of elsewhere (see Saliva, Se- cretion), it may be interesting to remark, that the salivary glands, although immediately surrounded by muscles, are not necessarily compressed in the different movements of the jaw. This conclusion has been arrived at by a series of interesting experiments and in- ductions due to Bordeu, but into the analysis of which it would be beyond the limits of this article to enter.* Morbid Anatomy. — The parotid gland is far more frequently the subject of disease than either the submaxillary or sublingual. The idiopathic inflammation of these glands is known under the name of Cynanche parotidea, vulgarly translated " mumps." The submaxil- lary is occasionally, and the subUngual but rarely implicated. The surrounding soft parts, particularly the lymphatic glands, participate in the inflammation, tending greatly to increase the swelling. On account of the intimate relation of the glands with the jaw, consider- able pain and inconvenience form a prominent svmptom. The saliva is at first increased, and subsequently diminished in quantity. Suppuration very rarely occurs. Secondary inflammation takes place as an occasional com- plication of the different forms of fever. In eighteen cases of typhoid Louis observed one in which the parotid was implicated. The man died on the thii*ty-ninth day of the attack ; and nine days prior to death pain supervened in the parotid glands, which were found after death to be twice their ordinary volume, and studded throughout with small purulent deposits. The chief point of interest, however, to the surgeon and anatomist, in connection with inflammation of the parotid, is the formation of abscess in the region of the gland. This may either take place in the subcutaneous cellular tissue superficial to the parotid fascia, or in the substance of the gland beneath that fascia. It generally occurs, in the one form or the other, in connection with phlegmonous erysipelas of the face and neck. Abscesses forming in the latter situation demand the prompt attention of the surgeon, inasmuch as they are attended with the most severe con- stitutional symptoms, which are only relieved by a free incision through the dense fibrous envelope of the gland : unless thus treated, the matter either makes its way through the external auditory canal, by passing between its bony and cartilaginous divisions, or, after the most severe symptoms, bursts externally in the parotid region. It may even extend deeply into the neck as far as the trachea, and terminate by effusion into the chest and * Bordeu, Eecherches Anatomiques sur la Position des Glandes, et sur leur Action. Paris, An. viiL — death. Independent of this extensive bur- ro\\ing, matter pent up beneath the parotid fascia may exert a most injurious influence by compression of the larger vessels of the neck, the structure of the gland itself, and the facial nerve. Examples, in fact, are on record of almost complete destruction of the gland itself, and incurable facial paralysis, from neglect of incising the parotid fascia at an early period of the formation of pus beneath it. In inflammation of the salivary- glands, whether primary or secondary, the areolar tissue of the gland is most usually affected ; in a few instances, however, the true structure of the gland is impUcated. Berard* relates a remarkable instance of this kind, in which both the areolar and glandular tissue were affected. When the parotid was pressed, pus flowed into the mouth from Steno's duct. Abscesses connected with disease of the ear now and then make their way into the sub- stance of the parotid gland. Encysted tumours are occasionally observed in the body of the paiotid, and in all pro- bability are more in connection with the lymphatic glands than the gland itself, except in those cases where they arise from isolated collections of saliva, owing to obstruction in some part of the excretory canal. The latter formations are, however, but rarely met with, and, when so, occur usually in the track of Steno's duct. The parotid and submaxillary undergo also fibrous and carcinomatous degeneration. The latter affection, as a purely idiopathic change, is extremely rare ; and, although the records of surgery afford ample illustration of such in the parotid, according to the assertions of the authors of individual cases, the evidence in some must be received with considerable reserve. Carcinoma originating in the lym- phatic glands, superficially to or beneath the parotid fascia, or, lastly, in the paren- chyma of the gland itself, has been, in fact, indiscriminately described as carcinoma of the parotid gland. This subject has been minutely inquired into by Berard, as also the extir- pation of the gland j in a great number of the cases on record. He concludes his obser\a- tions, by remarking that scirrhus of the parotid generally calls for the extirpation of the parts affected : and supports this conclusion by ob- serving, that relapses after the operation are comparatively rare. This inference is at variance with the opinion of many practical surgeons ; and it would require a much more extensive and impartial series of statistics than we at present possess to arrive at a definite conclusion on the subject. No greater difficulty exists than to obtain the subsequent history of apparently successful cases in sur- gery, and that of those in which the parotid has been extirpated forms no exception to the remark. In the case related by Mr. Luke J, * Berard, Maladies de la Glande Parotide, et de la Ee'gion Parotidienne. 8vo. Paris, 184L t Loc. cit, J London Medical Gazette, Feb. 5, 183L SALIVARY GLANDS. 431 and in which there is every thing to show that the parotid was entirely extirpated, the disease returned at the end of a year, and terminated fatally. In Mr. Solly's case*, in which the ascending ramus of the jaw was removed, in order to extirpate the gland as completely as possible, the disease, instead of being confined to the parotid gland, was found, a few months afterwards, by the death of the patient, to have proceeded from the brain. Other cases, again, have been described as carcinomatous affections of the parotid, but in which their details by no means indicate that such was their nature. The case related by Larrey, for example, and which he considered to be one of carcinoma, will appear, we think, on a careful perusal, to have been nothing more than a strumous affection of the lymphatic in the substance of the gland, or possibly of the gland itself, " which had degenerated into a dense yellow lardaceous substance." A remarkable case of hypertrophy of the parotid is related by Tenon. % It had the form of a tumour, of the size of the fist, ex- tending from the ear to the angle of the lips ; it was soft, white, indolent and movable, some large vessels here and there ramifying on the surface. The arteries, on the death of the child, were found considerably en- larged, which circumstance, in all probability, accounted for the condition of the gland. Berard also met with a similar case in a child three years old. The tumour was of almost the same volume, but simulated an erectile tumour. The veins were found very much enlarged and the arteries normal, the cellular tissue reddish and granular, and the true tissue of the gland remarkably hyper- trophied. Scdivari/ fistuIcE occur in the course of the excretory duct of the parotid, in it or its smaller ramifications, and arise from accidental injury, the result of inflammation, or from ulceration of a salivary tumour, which has gradually enlarged in consequence either of inflammatory obstruction at some part of the duct, or the presence of calculi. Marti relates the case of a congenital de- formity of the parotid duct (simulating fistula) in an otherwise healthy female infant. § The orifice opened on the exterior of the right cheek, down which the saliva flowed. The exact nature of ranula has not been clearly determined. It consists of a sublingual tumour, varying considerably in size and density. Some consider it as a mere dilatation of the duct from obstruction at its orifice ; others as a submucous tumour, external to the duct, causing its compression ; and others, again, as an encysted tumour developed in its interior. Although the analysis of the con- tained fluid (see Saliva) would appear to * London Medical Gazette, Dec. 19, 1845, and July 14, 1848. t Memoire de I'Extirpation des Glandes Sali- vaires. X Histoire de I'Academie des Sciences pour I'anne'e 17 GO, quoted by INIurat. § Marti, De Loco pra;ternaturali Orificii Ductus Salivalis Stenoniani sanato. 1746. indicate that the last opinion were correct, it is by no means certain whether mere ob- struction at the orifice of the duct may not give rise to a similar change in the quality of the saliva. The morbid condition of the labial glands has been made the subject of distinct inquiry by Sebastian*, who arranges their affections under the heads of — 1. Obstruction of the excretory duct. 2. Atrophy. 3. Tumefac- tion with hyperaemia. 4. Ulceration. The first affection occurs under two forms : The one as a transparent painless tumour of a bluish tint, resembling a vesicle or hydatid in the substance of the lip, of the size of a pea, and containing a transparent viscid fluid. He has only met with it in the lower lip, on the right side, near the angle of the mouth, and always solitary, and of quick formation. The other form is comparatively frequent, and appears as small round elastic, more or less transparent indolent tumours, frequently as many as fifteen in the lower lip. They exude on puncture a thick, viscid, greasy matter. The second affection is distinctly re- marked in the incipient stage of cancer of the lip, which, according to his opinion, com- mences in the cellular tissue. The third occurs in folHcular duodenitis ; and typhoid fever, as observed by him in children. He has frequently met with the fourth affection in phthisical individuals, &c. Comparative Axatomy. — The first ap- pearance of a salivary apparatus has been ob- served by Owen, in a genus of Entozoa found in the stomach of the tiger, and named by him Gnathostoma. It consists of four elongated straight blind tubes, each about two lines in length, placed at equal distances around the commencement of the alimentary canal, having their small extremities directed forward, and opening into the mouth. f Among the Echinodermata the salivary organs in Holothuria regalis are represented by elongated cascal processes, surrounding the oesophagus, and continued into the branched tentacles around the mouth. They exude a viscid secretion, which assists in entangling the objects which constitute the food of the animal, lubricating them, and adapting thera for deglutition. In Myriapodn the salivary glands consist of small transparent vesicles, constituting in Julus terrestris, for example, a clavate mass, the small extremity of which terminates in a tv/isted excretory canal opening into the pharynx. They are large and very vascular in the Scolopendridae. In the Insecta the salivary glands evacuate themselves either into the mouth, or the com- mencement of the intestine in front of the stomach. They are arranged by Burmeister as fol- lows I ; — * Loc. cit. f Proceedings of the Zoological Societv, 1836. p. 125. X Burmeister's Manual of Entomology, trans- lated from the German by W. E. Schuckard, p. 144. 432 SALIVARY GLANDS. A. Salivary vessels opening into the mouth, generally beneath the tongue, and more seldom at the base of the mandibles. They take the following forms : — 1. Simple, long, undivided, twisted tubes : thus in the majority of insects, viz. all butterflies, many beetles and flies. 2. As a narrow vessel which empties it- self into one or two bladders, whence the salivary duct originates (Nepa, Cimex^ Sarcophaga). 3. As a ramose vessel with Wind branches (Blaps). 4. As two long cylindrical pipes, which unite into one excretorj^ duct. 5. As four small round bladders, each pair of which has a common duct (Pulex, Lygoeus, Cimex). 6. As a multitude of such vesicles in Nepa. 7. As capitate tubes, in the free ends of which many very fine vessels empty themselves (Tabanus). 8. As tubes which at intervals are sur- rounded by twirhng blind bags (Ci- cada). 9. As granulated glands which on each side unite into a salivary duct, both of which join into a single evacuating duct (Gryllus). B, Salivary glands which empty them- selves into the commencement of the stomach, as short or long bags, either simple or furnished with processes (Bu- prestis); other forms as well as those just cited, are found among the Diptera : — L As two capitate tubes, into the free ends of which many delicate vessels open (Hemerobius perla). 2. As two short processes of the same width as the stomach (Leptis and Acheta). 3. As two bags covered entirely with short blind processes (Bombylius, Bu- prestis). 4. As triangular processes, each edge of whicii is occupied by a row of vesicles (Chrysotoxum). 5. As six narrow tubes which surround the commencement of the stomach (Gryllus). 6. The blind processes which clothe the stomach in the predaceous beetles. In Cirrhopoda the salivar}^ glands are two in number and of considerable size, opening into the commencement of a short oesopha- gus. Among PterojKxla they are found in Clio as two long and slender glands placed at the sides of the oesophagus, and pouring their secretion into the mouth. They " present in the Gasteropoda different forms and degrees of development bearing the ordinary relations to the construction of the mouth and the nature of the food. In the Calyptraea they are represented by two simple elongated se- creting tubes. In the whelk they present a conglomerate structure, and are situate at each side of the oesophagus at the base of the proboscis, along which they transmit their slender ducts to terminate on each side the anterior spines of the tongue." (Owen.) In the snail they are flattened, elongated, and irregular in form, and conglomerate in struc- ture, diminishing in breadth as they proceed upwards to the pharynx, where their ducts terminate. In the Vaginulus an additional slender tube which lies first on the stomach, passes through the nervous collar to join the duct by which the saliva is discharged. The salivary glands are present in all the Cejyhalojjoda, with the exception of Loligo- psis. In the Onychoteuthis two glands are situated at the root of the tongue. They are in general, however, four in number, two at the root of the tongue, which give oft' distinct ducts which terminate at the commencement of the oesophagus ; the other pair, generally longer than the superior, is lodged in the vis- ceral sac, on each side of the upper part of the crop. The ducts of the last form a single tube which opens in the neighbourhood of the spiny portion of the tongue. The salivary glands are absent in Pisces. Among reptiles in the Chelonian, Saurian, and Batracliian orders, the substance of the tongue seems principally made up of a glan- dular mass formed by a multitude of little tubes united at their bases, but becoming se- parate towards the surface of the tongue. In the OiMdian reptiles two glandular organs placed immediately beneath the skin of the gums surround the margins of the upper and lower jaw, and pour an abundant salivary secretion into the mouth. (Rymer Jones.) In many genera the salivary apparatus is de- ficient. The |3oison glands of serpents can hardly be reckoned among the salivary organs, being destined for a special secretion, and forming the analogues to similar glands in the Arachnida. In Aves the salivary glands present con- siderable variation in their number, position, and degree of development. In the crow the only indication of a salivary apparatus is a series of simple cone-shaped follicles, placed along the sides of the oral cavity, upon the mucous membrane of which they open by distinct orifices. In general, however, there are four pairs, two sublingual on each side beneath the tongue, two maxillary divided each into an anterior and posterior, and opening by special ducts in front of the tongue, and a gland which can be compared to the parotid. These are generally all present in the Rapaces^ Pas- scres, and Gallinct ; and appear to be absent in Sula, Carbo, and Phaenicopterus, and but slightly developed in the GruUce and Palmi- pedes generally. In the goose they occupy the entire space included between the rami of the lower jaw, being closely united in the median line, and opening into the mouth on each side of this by a series of orifices. In the watercoot and Hirundo esculenta, the parotid is highly developed, in the latter the secretion serving for the preparation of SCAPULAR REGION. 433 its edible nests. In the woodpecker the glan- dular mass is of extraordinary size, extending from the angle to the symphysis of the jaw on each side, and opening by the confluence of the two ducts into a single orifice at the apex of the mouth. In Mammalia the salivary glands present considerable variation. In the Monotremata they are partially deficient : in the Echidna there appears to be no parotid ; the submax- illary, on the other hand, is highly developed, extending from the meatus auditorius along the neck, and upon the anterior part of the thorax. Its ducts terminate by numerous orifices on the membranous floor of the mouth, and pour out a secretion for the lubrification of its long and slender tongue. In the Cetacea the salivary glands are absent. In the Dugong, however, one of the herbivo- rous Cetacea, the parotids are highly deve- loped. In the Ruminajiiia the three pairs are highly developed, particularly the parotid ; and in addition to these there is a group, apparently continuous with the molar, which mounts up along the superior maxillary bone, beneath the zygoma, to the globe of the eye, as observed in the ox, the sheep, and the horse. The excretory ducts pierce the mu- cous membrane near the posterior margin of the superior alveolar ridge. In the armadillo, among the Edeiitata, the submaxillary gland has appended a reservoir or bladder, receiving the saliva by small ducts, which open into it posteriorly in a valvular manner. A single duct comes off from its anterior part, and terminates just behind the symphysis of the lower jaw. The saliva is very tenacious, the serous part being pro- bably absorbed during its detention in the reservoir, and is expelled at the extremity of the mouth, in order to lubricate the tongue, which is by this means rendered subservient, as in the ant-eater, to the catching of insects. In the latter animal the salivary secretion takes place from two glands, situated, accord- ing to Cuvier, the one in contact below with the upper edge of the masseter, and filling up a great part of the temporal, zygomatic, and orbital fossae ; the excretory duct opening into the mouth behind the superior maxilla : the other, probably furnishing the viscid secre- tion that coats the tongue in front of the tendon of the masseter, behind the angle of the lips, and then running along the edge of the lower lip as far as the middle. Its canal opens externally at the commissure of the lips. In the Carnivora the variations of the sali- vary glands are but slight. The submaxillary in them, as in the Rodentia and Ruminantia, are large. The sublingual gland is absent in the cat. The writer of this article has to acknowledge his obligations to the undermentioned sources, for the preceding account of the comparative anatomy of the salivary glands: — Cuvier, Le- 90ns d' Anatomic comparee ; Owen's Lectures on the Invertebrata; R3^mer Jones, General Structure of the Animal Kingdom ; Wagner, Elements of Comparative Anatomy, trans- lated by Tulk ; Kelp, De Systemate Salivali, VOL. IV. and the various articles on Comparative Ana- tomy in this Cyclopaedia. Bibliography. — JS^ck, Disquisitio Anatomica de Ductibus Salivalibus, 1656. Wharton, Adeno- graphia sive Glandularum totius corporis Descriptio, 1659. Haller, Dispiitationes Anatomicae, vol. i. p. 1, ad 92. Stejw (iV.), De Musculis et Glandulis Ob- servationum Specimen, &c., 1664 ; Observationes Anatomicae quibus varia Oris Oculorum et Narium Vasa describuntur, novique Salivas et Muci Fontes deteguntur, &c., 1662. Vater, Novi Ductus Sali- valis in Lingua Excretorii Demonstratio, 1723. Siebold (J. Barth), Diss. Inaug. Med. sistens His- toriam Systematis Salivalis Physiologice et Pa- tliologice consid., &c. Jenae, 1787. Murat, Sur la Glande Parotide consideree sous ses Rapports Ana- tomiques, Physiologiques, et Pathologiques, 1803. Midler, De Glandularum Secernentium Struct. Pe- nitior, 1830. Bordeu, Recherches Anatomiques sur la Position des Glandes, et sur leur Action. Panizza (5.), Remarques Chirurgicales sur la Glande Paro- tide. Annales de la Chirm-gie, Paris, 1844, t. x. p. 54. Vide also the Bibliography of GLAND. {Nathaniel Ward.) SCAPULAR REGION (Descriptive AND Surgical Anatomy of). The term sca- pular region is intended by some anatomists to comprise all the structures which lie on the scapula, on its anterior as well as on its pos- terior surface; but, in accordance with the arrangement of Velpeau and others, we limit the term scapular region to the posterior as- pect of the scapula, regarding its anterior, or subscapular, surface as appertaining to, and forming one of the boundaries of, the axillary region. Under the denomination then of scapular region, v/e include a portion of the posterior aspect of the shoulder, presenting a triangular outline, to which the following boundaries may be assigned. Its base, which is placed internally, is constituted by the ver- tebral margin of the scapula; its apex, placed externally, becomes continuous with the re- gion of the shoulder joint ; inferiorly, it is limited by the lower oblique edge of the la- tissimus dorsi muscle, which likewise separates it from the region of the axilla ; and above, the superior costa of the scapula constitutes its extreme boundary, and separates it from the great posterior triangle of the neck. Between the integuments and the dorsum of the scapula, which forms the floor of the region under consideration, lie numerous muscles, layers of fasciae, vascular inoscula- tions, branches of nerves, &c., which we shall describe in the order in which they present themselves in dissection. The muscles, which are numerous, may be divided into the extrinsic and the intrinsic ; the latter are, the fleshy portions only of the supra- and infra-spinati, and of the teres major and the teres minor muscles. Under the former class, we shall have to speak of portions of the trapezius, latissimus dorsi, and deltoid muscles. Numerous other muscles are at- tached to the different borders of the scapular region ; but these have been already described in the several articles treating of the regions to which they more properly belong (vide Neck, Back, Arm). The projection back- wards of the spine of the scapula naturally F F 434 SCAPULAR REGION. divides the scapular region into two distinct parts, termed by anatomists the supra- and infra-spinal fossae ; and in this article we shall describe, seriatim, the anatomical relations of the structures which occupy these two fossae respectively. The subcutaneous layer of areolar tissue, throughout the whole of the scapular region, is dense, and much more closely connected to the integument than to the aponeurosis be- neath. Very free motion of the skin on the deeper seated structures is thus allowed. In this layer, superiorly, we find some of the superficial descending branches of the cervical plexus of nerves passing towards the region of the shoulder, where they become lost in the integument. Beneath the skin, sub- cutaneous areolar tissue, and superficial layer of fascia, the trapezius muscle covers all that portion of the scapular region which corre- sponds to the supra-spinal fossa. The fibres of this muscle take a direction downwards, outwards, and forwards, across this region, to the upper edge of the spinous process, and angle of junction between the acromion pro- cess and clavicle, into which they are inserted ; the more posterior fibres are oblique ; the an- terior, coming from the superior crest on the occipital bone, descend more perpendicularly. This muscle acts powerfully as an elevator of the shoulder joint, its anterior fibres drawing the entire scapula upwards and backwards, and with it the upper extremity, whilst its posterior fibres effect the same purpose by producing a motion of rotation in the scapula, in virtue of which the posterior angle of that bone is depressed, and the anterior, or acro- mial extremity, proportionately elevated. In cutting through the trapezius muscle, the anatomist will probably meet with some of the terminal branches of the spinal accessory nerve distributed to this muscle ; as also descending branches of the supra-scapular artery, which, becoming superficial, maintain around the acromion process an anastomosis with the ascending (inferior acromial) branches of the acromial axis, and the circumflex branches of the axillary trunk. Beneath the trapezius muscle, and sepa- rating it from the fascia which covers the supra-spinatus muscle, a layer of fatty areolar tissue is always placed, which varies, however, in its amount, in different persons. In chronic disease of the shoulder joint, such as ulcera- tion of the articular cartilage, and, in fact, in all cases where inflammatory action has ex- isted in the articulation for any considerable length of time, this intermuscular fatty stra- tum becomes absorbed ; and to this circum- stance, as also probably in some degree, to atrophy of the muscular fibres, is due the pe- culiar flattening, or even the depression, so constantly observed above the spine of the scapula in such cases ; appearances analogous to the flattening of the gluteal region, which is one of the most remarkable external fea- tures of" morbus coxae." Deeper still is placed an aponeurosis of great strength, which forms, with the smooth concave surface of the supra-spinal fossa, an osteo-fibrous canal, containing the fleshy por- tion of the supra-spinatus muscle. This fascia is stretched between the superior costa and the spine of the scapula ; by its under surface, posteriorly, it affords attachment to the fibres of the supra-spinatus ; whilst ante- riorly it accompanies the tendon of that muscle, under the acromial end of the cla- vicle and the triangular ligament, losing itself on the capsular ligament of the shoulder joint. By the removal of this fascia, we bring into view the supra-spinatus muscle, filling accu- rately the fossa from which it derives its name, and from nearly the entire of which it derives its origin ; anteriorly, however, the muscular fibres have no ossific attachment. They here glide over the smooth, pulley-hke surface presented by the bone, and then, bending downwards and outwards, they form the tendon of the muscle, which is inserted further on into the upper facette of the great tuberosity of the humerus, becoming also in- corporated with the capsular ligament. In this part of their course the supra-spinatus muscle and tendon are concealed by the acro- mio-clavicular articulation, and more exter- nally by the coraco-acromial, or triangular li- gament, which is stretched in the form of an arch above them ; a bursa of large size inter- venes between the under-surface of the liga- ment and the superficial, or upper aspect of the tendon. By the removal of the trapezius muscle we are also enabled to see the attach- ments of several muscles to the edges of the supra-spinal fossa ; thus the insertion of the levator anguli scapulae into the posterior su- perior angle of the scapula becomes apparent ; also the attachment of the upper fibres of the serratus magnus anticus to its superior costa; and that of the omo-hyoid muscle to " the hgament of the notch," and the base of the coracoid process. In this situation also the supra-scapular nerve and artery enter the supra-spinal fossa, usually separated from one another by " the ligament of the notch." The nerve, in the majority of instances, being beneath, and the artery above, the ligament, the nerve is transmitted through a foramen, formed by the notch in the upper edge of the scapula and the ligament of the notch, whilst the artery enters the fossa through a small triangular interval, the respective sides of which are constituted by the ligament of the notch, coracoid process, and the posterior belly of the omo-hyoid muscle. The supra-scapular nerve is a branch from the upper division of the brachial plexus : in the neck it follows the course of the omo- hyoid muscle to the scapula, passes beneath the origin of that muscle and through the foramen above described ; after which it enters the supra-spinal fossa, and is distri- buted, firstly, to the supra-spinatus muscle ; secondly, to the infra-spinatus and teres minor muscles, by a branch which passes beneath the acromion process ; and, thirdly^ by a few twigs to the exterior of the capsule of the shoulder joint. SCAPULAR REGION. 435 The supra-scapulttr artery (sometimes de- signated arteria transversalis humeri) has elsewhere been described as arising from the thyroid axis of the subclavian trunk ; it passes at first downwards, and then nearly trans- versely outwards, anterior to the phrenic nerve, and between the sterno-cleido mastoid and the anterior scalenus muscles ; it next runs along the base of the supra-clavicular triangle in close contact with the front of the subclavian vein, behind the clavicle and sub- clavian muscle, and below the level of the subclavian artery, here in the third stage ; more externally it crosses this great trunk near the commencement of the axillary ; it then passes in front of the brachial plexus of nerves, running along with the supra-scapular branch, parallel to the omo-hyoid, and covered by the trapezius muscle, to the superior costa of the scapula, where it enters the supra- spinal fossa above " the ligament of the notch." Whilst under cover of the trapezius muscle, the supra-scapular artery gives off a large muscular branch, the ramifications of which have been alluded to as assisting to form the acromial anastomosis. The final distri- bution of the artery is by two branches. 1. supra-apiJial branch, "whhch. is distri- buted to the supra-spinatus muscle, and which anastomoses near the posterior superior angle of the scapula, with branches from the pos- terior scapular artery. 2. The infra-spinal branch, which enters the infra-spinal fossa by passing beneath the acromion process, and the " spino-glenoid ligament " of Sir Astley Cooper ; here it is distributed to the deep surfaces of the muscles of this region, and anastomoses freely with the termination of the posterior scapular, and with the posterior branch of the subscapular arteries. The structures thus shown to be contained in the supra-spinal division of the scapular region are the following : — 1. Integument, dense areolar tissue, and superficial nerves ; 2. A thin aponeurosis covering, 3. The trapezius muscle ; 4. A layer of fatty areolar tissue ; 5. The strong supra-spinal aponeu- rosis ; 6. The supra-spinatus muscle ; 7. The supra-scapular vessels and nerve ; 8. The smooth concave surface of the bone (fossa supra-spinata). Below the spine of the scapula portions of the trapezius, deltoid, and latissimus dorsi muscles overlap the scapular region, and partly conceal from view the intrinsic muscles of the infra-spinal fossa. These muscles are covered by an aponeurotic expansion, which is thin over the trapezius and latissimus dorsi muscles ; more dense and strong where it covers that part of the deltoid which belongs to the region of the shoulder ; and much stronger still, where it invests the infra-spi- natus and teretes muscles ; superiorly, it is attached to the lower edge of the spine of the Bcapula ; posteriorly, it is connected with the tendinous expansion of the trapezius muscle, and the base of the scapula. From its deep surface, septa are detached, which pass in between the subjacent muscles, and contract firm adhesions to the bone ; whilst, at the posterior edge of the deltoid muscle, it divides into two laminae, between which that muscle is enclosed ; the superficial layer covers the outer surface of the deltoid, and so becomes identified with the fascia of the arm ; whilst the deeper layer, passing beneath the deltoid muscle, becomes continuous with the capsule of the scapulo-humeral articulation. The trapezius and latissimus dorsi muscles overlap — the one, the posterior superior, the other, the inferior angle of the scapula. The trapezius is tendinous where it glides upwards and forwards over the smooth triangular sur- face situated behind the spine of the scapula. A bursa here intervenes between the bone and the flat tendinous expansion of the muscle. The latissimus dorsi, by its fleshy fibres, over- laps the inferior angle of the scapula. The di- rection of the muscle at this part of its course is nearly horizontal. As these fibres pass off the scapula, they are joined by those of its costal origin, and thence they all run upwards and forwards, presenting a twisted appearance to their insertion, which takes place by a narrow flat tendon into the bottom of the bi- cipital groove of the humerus. Both these muscles, from their pecuHar relation to the scapula, serve to compress it against the thorax, and so to prevent its being unduly separated from the trunk in the varied and extensive movements which it enjoys. A peculiar displacement of the scapula, the result of accident, has been described by Vel- peau, who supposes it to depend on paralysis of the serratus-magnus from injury of the great posterior thoracic nerve (external respi- ratory, Ch. Bell), which is distributed to that muscle. The appearances observed in the case detailed by Velpeau were, remarkable projection backwards of the scapula, especially of its posterior border, and inability on the part of the patient to bring it in contact with the side of the thorax : cases corresponding in their general features to this description have been seen by almost every surgeon. In those which have occurred in the writer's ex- perience, the projection of the posterior edge and of the lower angle of the scapula was very remarkable, and the movements of the upper extremity were greatly impeded. Mr. Adams has suggested, as a more plausible ex- planation of the deformity in these cases, that the lower angle of the scapula escapes from under the latissimus dorsi muscle; an accident which ma}' occur from too great elevation and abduction of the upper extremity ; and the more easily, as, in the majority of instances, either the muscle is not attached to the bone at all, or else it adheres to it by a few small fibres only. The deltoid, trapezius, and latissimus dorsi muscles, where they overlap the scapular re- gion, circumscribe a triangular space, in which may be seen part of the posterior edge of the scapula, with the attachment to it of the rhomboid muscle, and also a portion of the infra-spinatus and of the teres minor muscles. F F 2 436 SCAPULAR REGION. By the removal of so much of these super- ficial muscles as encroach on the scapular re- gion, and of the strong fascia already de- scribed, the deeper seated muscles of the infra-spinal fossa, viz. the infra-spinatus and the teres major and minor, are completely exposed. The infra-sjnnatus muscle arises from the upper four-fifths of the dorsum of the scapula below its spine. The strong fascia of invest- ment already described also furnishes an extensive surface of origin to its fibres ; the muscle is triangular, the fibres all converging anteriorly to their common tendon, which, passing beneath the spine of the scapula and the acromion process, approximates closely to the tendon of the supra-spinatus muscle, and is inserted immediately beneath it, into the great tuberosity of the humerus. The teres minor muscle seems to be little else than a fasciculus of the last described muscle, to which it is parallel, and along the lower edge of which it is placed : anteriorly, it is inserted by a separate tendon into the lowest portion of the great tuberosity of the humerus. The teres minor and infra-spina- tus muscles might be regarded as different portions of one and the same muscle, not only from the similarity of their anatomical rela- tions, but also fi'om the identity of their physiological functions; both draw down- wards and backwards the humerus, and pro- duce the rotation outward of the arm at the shoulder joint. The teres minor is placed between the infra-spinatus superiorly and the teres major inferiorly, in close contact with the former, from which an aponeurotic septum and branches of blood-vessels alone separate it ; whilst a very considerable space, containing the long head of the triceps, and some im- portant nerves and vessels, intervenes between it and the teres major. The teres vmjor and the teres minor mus- cles arise close together from the lowest portion of the dorsum of the scapula. The teres major (the more superficial of the two at its origin) is attached to the rough surface on the outer aspect of the inferior angle of the scapula, whilst the teres minor arises more anteriorly, from a narrow but well-marked groove, situated just above the axillary margin of the bone. At their origin the teres minor is concealed by the teres niajor, but as they pass towards the humerus they gradually diverge, and are inserted on different aspects of the bone, and at different levels, so that the long head of the triceps firstly, and the neck of the humerus secondly, intervene be- tween them. The teres minor is inserted on the outside of the humerus into its great tuberosity, below the insertion of the infra- spinatus muscle, whilst the teres major, in company with the latissimus dorsi, passes on the inner aspect of the humerus, and is in- serted along with it into the bottom of the bicipital groove: at their insertion, the tendon of the teres major is posterior, and a little inferior to the tendon of the latissimus dorsi. The teretes muscles, in diverging to the humerus, form with the upper part of that bone a triangular space, of which the base is at the humerus, and the apex at the inferior angle.of the scapula. The scapular origin of the triceps extensor muscle in its vertical course down the arni, crosses this space, and divides it into compartments, a posterior triangular, and an anterior quadrilateral one, through both of which the axillary cavity communicates with the posterior region of the scapula and shoulder. The triangul'tr covipartment, overlapped posteriorly by the deltoid ir.uscle, is bounded, above, by the teres minor and axillary edge of the scapula; below, by the teres major. Its base, situated externally, is formed by the long head of the triceps ; whilst its ajpcx, directed inter- nally, corresponds to the point of contact of the teretes muscles, where they arise together from the scapula. In this compartment is seen the posterior branch of the sub-scapubr artery {circumjlexus scapidce, Soemmering), forming here a curve, the convexity of which is directed downwards and backwards. The artery leaves this space by bending upwards and backwards, bereath the teres minor and infra-spinatus muscles. It thus arrives in the infra-spinal fossa, lies next the bone, and ramifying minutely anastomoses, superiorly with the descending branch of the supra- scapular artery, and posteriorly with the termination of the posterior scapular artery. (^Vide Axillary Artery.) The quadrilateral compartment is bounded above, by the capsular ligament of the shoulder joint, by the prominence of the head of the humerus, and by the tendinous attachments of the teres minor and of the sub-scapularis muscles ; below, by the teres major and latissi- mus dorsi ; externally, by the neck of the humerus ; whilst, internally, it is separated from the triangular compartment last de- scribed by the long head of the triceps muscle; it transmits, from within outwards, the circum- flex nerve and posterior circumflex artery. This artery contributes to form the great scajndar anastomosis ; some of its branches ascending in the substance of the deltoid muscle, inosculate freely with the superior acromial branches of the infra-scapular artery, whilst others pass backwards and unite in the infra-f^pinal fossa, with branches of the sub- scapular and the posterior scapular arteries. The circumflex nerve is distributed almost exclusively to the deltoid muscle ; but two collateral branches are detached from it, which are distributed in the scapular region; the first, a branch to the teres minor muscle ; the second, a cutaneous filament, which escapes from beneath the posterior edge of the deltoid muscle, and is distributed to the integument. The posterior scapxdar artery, although placed beyond the limits of the scapular region, may, nevertheless, be here described, as it is distributed chiefly to the parts con- tained within it. Under the name of "trans- versalis colli" this artery arises in the neck from the thyroid axis, near to, and sometimes by a common trunk with, the transversalis humeri ; it sometimes comes from the sub- SCAPULAR REGION. 437 clavian, external to the scaleni muscles, — an irregularity which is by no means uncommon. When derived from its more usual source^ this branch runs transversely across the scalenus anticus muscle and the phrenic nerve, covered by the clavicular portion of the sterno- cleido-mastoid muscle: it then traverses the apex of the supra-clavicular triangle, lying above the level of the curve of the subclavian artery, and placed before or between the for- mative roots of the brachial plexus ; passing still further outwards it gets under the trapezius muscle, and here gives off its ascending cer- vical branch ; at the posterior superior angle of the scapula, the artery bends backwards, under cover of the levator anguli scapulas ; here it changes its direction, and inclining downwards, runs along the vertebral edge of the scapula. Its course may, therefore, be divided into two stages ; the first extends from the origin of the artery to the superior angle of the scapula, and so far its direction is nearly horizontal, and it is properly desig- nated the "arteria transversalis colli." In its second stage, the artery runs vertically, parallel to, and about an inch distant from, the vertebral margin of the bone. This portion of the artery, which alone should be termed " posterior scapular," is covered by the great- er and the lesser rhomboid muscles, and by the trapezius. To these, and to the other muscles attached to the scapula, it furnishes numerous branches, and at the inferior angle of that bone, it anastomoses very freely with the posterior branch of the sub-scapular artery. The structures which occupy the infra- spinal fossa may here be briefly recapitulated : first the integument and the sub- cutaneous layer of areolar tissue ; secondly, the fleshy edges of the deltoid and the latissimus dorsi muscles, and the triangular tendinous expansion of the trapezius, covered by their respective portions of fascia: in the interval between these muscles, and partly covered by them, lie, thirdly, the infra-spinatus, the teres major, and the teres minor, muscles ; these are con- tained in distinct sheaths, formed by their investing fascia, and the aponeurotic septa detached from its deep surface ; fourthly, the anastomoses of branches from all the scapular arteries; fifthly, the bone (fossa infra-spinata). Around the margins of the scapula there exists, as has thus been shown, a chain of large blood-vessels, which, by numerous branches, anastomose freely at the angles, and on the different aspects of the bone, forming a vascular circle of great interest to the surgeon ; for by means of it the upper extremity is mainly supplied with blood, when the current through the subclavian is inter- rupted, at the distal side of the branches which spring from its first stage. At the acromial end of the scapula two series of anastomoses may be observed ; the first, su- perficial to the acromion process, is formed by the union of the superior acromial branches of the supra-scapular artery with the ascending (inferior acromial) branches of the circum- flex, and with the acromial thoracic divisions of the axillary artery. Secondly; an anastomosis occurs beneath the acromion process and behind the glenoid cavity, bet ween the supra- and the sub-scapular arteries. Thirdly; at the posterior angle of the scapula, the supra- and the posterior scapular arteries anastomose, in the posterior part of the supra- spinous fossa. Lastly ; at the inferior angle, a free commu- nication exists under cover of the infra-spina- tus muscle, between the supra-, the posterior, and the sub-scapular branches, aided by the posterior circumflex. Through all these channels the sub-clavian and the axillary trunks communicate with each other, and experience has shown that full reliance may be placed on the capability of this anastomosis to maintain the circula- tion in the upper extremity after a ligature has been placed on the subclavian artery in the second or third stage. The veins of the scapular region merit no particular description ; they are very numer- ous, and communicate freely with each other. They accurately follow the course of the arteries. Those which lie above the spine of the scapula form one or tu o trunks of con- siderable size, which accompany the supra- scapular artery, and unite with the subclavian vein, external to the scalenus muscle; those of the infra-spinal fossa constitute a very large trunk, the sub-scapular vein, which enters the axilla and joins the axillary vein, as it lies on the posterior wall of the axilla; the sub-scapu- lar vein here forms an important anterior relation to its accompanying artery. The lymjihatics of the scapular region are arranged in two sets ; the superficial which pass to the ganglia of the axilla, and a deep set which closely correspond to the course of the bloodvessels, and terminate, as do the venous trunks, in the supra- clavicular and in the axillary regions. The scapular region participates in the remarkable mobility of the bone which sup- ports it, but as its motions cannot be regarded independently of those of the shoulder joint, we refer to the article on that subject for their elucidation. The uses of the scapula may be briefly stated as follows : — In the first place it con- nects the upper extremity to the trunk, and participates in, and is subservient to, many of the movements enjo} ed by the upper extremity. Secondly, it furnishes, by its flat surface, a lateral protection to that portion of the thorax against which it is applied. Thirdly, it is concerned in the mechanism of respiration, furnishing processes and surfaces for the attachment of numerous muscles, which are capable of altering the capacity of the thorax. This latter function of the scapula is well illustrated by cases where the upper extre- mities are totally wanting, in which the mus- cles, passing from the scapula to the thorax are well-developed, and act with vigour in effecting the full expansion of the thorax. F F 438 SCROTUM. This fact is mentioned on Sir Charles Bell's authority, from whom we also quote the fol- lowing short passage : — "We would do well to remember this double office of the scapula and its muscles, that whilst it is the very foundation of the bones of the upper extre- mity, and never wanting in any animal that has the most remote resemblance to an arm, it is the centre and "poijit d'appui " of the muscles of respiration, and acts, in that capacity when there are no extremities at all. " Percussion and auscultation are constantly practised over the scapular region, the super- ficial position of the spine of the scapula causing it to furnish satisfactory results when percussed, w hilst the nature of the respiratory sound, in the subjacent portions of the lung, may be easily learned by applying the stetho- scope to the supra- or infi-a-spinal fossa. The scapular region is sometimes the seat of fui'uncular viflammation, and of anthrax, which selects in general the posterior a-pect of the body, where the sub-cutaneous areolar tissue is most dense, often shows a special preference for the scapular region. Here likewise practical surgeons are well aware that chronic abscesses ("absces froid ") not un- frequently occur. Collections of matter in this situation are generally unconnected with any other local disease, but at the same time indicate consti- tutional derangement, more or less profound. Chronic abscess in this locality is not always superficially seated ; it may have for its site the loose areolar tissue beneath the scapula, which connects the sub-scapularis to the ser- ratus magnus muscle. Here it may attain a great magnitude, and displace the scapula outwards to a considerable distance from the trunk. Fractwes of the body of the scapula are met with as the result of direct violence only, and occur less frequently than the slightness of the bone would lead one a priori to expect. The numerous muscles covering the bone, which form for it an elastic cushion, and its strong projecting spine, are sources of protec- tion to which the scapula is indebted for its comparative immunity from this form of injury. Ablation of large portions of the scapula, or even the complete removal of that bone with part of the clavicle, and the scapulo-humeral articulation, has been had recourse to in cases of extensive injurj' of the shoulder, as from gunshot wounds. (Larrey.) In the Hopital des Invalides at Paris may be still seen hving examples of the success which sometimes attends even such severe mutilations; whilst the records of British sur- gery also furnish successful instances of the complete removal of the scapula, scapular end of the clavicle, and upper extremity, for tumours of great magnitude occupying the region of the shoulder, of w hich the cases by Mr. Fergusson and the late Mr. Liston are amongst the most remarkable. {B. Geo, M'Dowel.) SCROTUM. Latin, per metath. a scor- turn, i. e. pellis ; koovkoc, wrx^oc, 6\fvc, Gr. ; der Hodeiuack, Germ. Neither the Endish nor French language appears to have retained any word exclusively significant of this part of the body. In the former tongue, the Saxon word' " cod," a husk, or shelT, or bag, seems to have been originally applied to it in common with other legumentary tissues ; e. g. " peascods." Subsequently, however, the meaning of the word was extended, and from the containing tissues came to imply the contents. It is now obsolete, and the only term popularly retained in both languages is *' the purse,' " les bourses,"^ either in allusion to the scrotum resembling a purse, or from its tegumenlary nature (orpcra, pellis). The scrotum is the pouch or fold of integu- ment in which the testicles are placed, where they occupy an external position. It is com- posed of skin and areolar tissue, and is plen- tifully supplied with vessels and nerves. It contains the testicles, their cremaster rauscie, and serous membrane, together with their ar- teries, veins, nerves, and efferent duct, and a considerable length of the spermatic cord, which continues these into the abdominal canty. The skin of the scrotum is continuous above and in the middle hue with that which covers the inferior or urethral surface of the penis, and on each side with that of the lower part of the belly, the inguinal region, and the inner side of the thigh : behind, it is continuous with the perineum. Its colour is darker than the neighbouring in- tegument, and in the adult its surfiace is sparmgly occupied with hair ; in health it is rendered irregular by the presence of nu- merous rugae or furrows, the larirer of which take a transverse direction. The median line offers a prominence which extends back- wards to the anus, and which, from its like- ness to a suture, modem anatomists have named the raphe* {oaoi), sutura). The areolar tissue of the scrotum is conti- nuous with, or, in anatomical language, de- rived from, that of the perineal and inguinal regions. The more superficial or subcuta- neous fascia, together with that deeper lavCT which is attached to Poupart's ligament and to the ramus of the pubes, converges towards the scrotum; the two layers uniting t^ en- sheath the spermatic cord and testicle of each side in a cylindrical prolongation, the apposi- tion of the two bags in the middle line form- ing a common partition, the septum scroti. The texture of this covering of areolar tissue is peculiar, or even sui generis, and perhaps led to its receiving the appellation of the dartos (^caproCf tunica). It is xery deli- cate, and highly elastic, and is usually of a reddish or pink colour ; but it is not unlikely that this phenomenon maybe of post-mortem occurrence : and it has the additional pecu- liarity of being destitute of the fat which is * Its prof>er Greek name is iff*s- The etymology of the word is unknown, but it is used by Aris- tophanes and GaJen. SECRETION. 439 found in connection with this tissue in most parts of the body. Later researches have shown a still further difference, viz. the pos- session of another structure — the unstriped or organic muscular fibre — which is either not present in the subcutaneous textures of other regions, or is in far more sparing quan- tity. The contractility which is the function of these fibres is quite independent of the will, and is not only readily developed on the ap- plication of a direct stimulus, but is also pro- ducible by cold, and is associated with general tonicity of the system. And in opposite con- ditions of warmth or debility, a relaxation of these fibres effaces the rugae which their con- traction had previously produced. The vessels of the scrotum are numerous, but of little surgical importance ; they are derived from those of the thigh and perineum. The superior and inferior external pudic, from the femoral artery, terminate by sending many small twigs to the integuments of the penis and scrotum ; while, posteriorly, the internal pudic of each side sends forwards a superficial perineal branch, which likewise ends in these tissues, by ramifying and anastomosing with the preceding. The accompanying veins have in all respects a corresponding distribution. The nerves are chiefly the anterior termi- nations of those seen in the perineal space. Thus on each side is the inferior pudendal, which leaves the sacral plexus with the small sciatic nerve; while, nearer the median line, are the two superficial perineal nerves (ex- ternal and internal perineal). The branches of these are very numerous, and are traceable to the front of the scrotum. The ilio-in- guinal, a small branch from the higher part of the lumbar plexus, and which perforates the abdominal nmscles, together with a part of the genito-crural nerve from the same source, terminate near the front of the scrotum, but extend very little on it. For the anatomy of the contents of the scrotum, as well as its morbid appearances, the reader is referred to the article " Testicle," in which they will be included. ( William Brinton.) SECRETION. — This term is usually em- ployed to designate the process of separation of those matters from the nutritious fluids of the body, which are destined, not to be directly applied to the nutrition and reno- vation of its organised fabric, but (1) to be either at once removed as injurious to its welfare, or (2) to be employed for some ul- terior purpose in the chemical or physical pro- cesses of the economy itself, or to exert some kind of action upon other beings. The term is often used, also, to designate the products thus separated. The nature of this process of separation is essentially the same in all cases, whatever may be the destination of its products ; and we shall consider it, therefore, in the first place, without any further reference to them, than may suffice to indicate the boundaries of the three groups under which we have ar- ranged them. It is probable that in almost every act of secretion a double purpose is served, the blood being freed from some in- gredient whose accumulation would be super- fluous, if not injurious ; and the fluid sepa- rated having some secondary purpose to answer. Thus, whilst biliary matter becomes a positive poison if it be retained in the blood, it serves an important purpose, when poured into the duodenup.i, in completing the diges- tive process, and in preparing the nutrient contents of the intestinal canal for absorption. So, again, the cutaneous exhalation not only removes the superfluous water of the blood, but is one of the chief means of regulating the temperature of the body; whilst the sebaceous matter, poured forth by the glandulas of the skin, serves to lubricate its surface, at the same time that it relieves the blood of matter which, not being nutritive, is extraneous. Even the urine, which seems to be eliminated merely for the removal of noxious matters from the blood, is sometimes made to serve an additional purpose, its acridity, or its pe- culiarly offensive odour (increased under the influence of terror), frequently rendering it an effectual means of defence. On the other hand, the substances which are separated from the blood for the purpose of discharging some important office in the economy, usually, if not always, contain some substances whose retention in the blood would be injurious, and which are therefore advantageously got rid of through this channel. Thus the sa- livary, the gastric, and the pancreatic fluids all contain an animal principle nearly allied to albumen ; but this principle seems to be in a state of change, or of incipient decomposition ; and it would seem not improbable, that whilst this very condition renders the albuminous matter useful in promoting the solution of the aliment, it renders it unfit to be retained within the circulating current. It is impossible, therefore, to divide the secreted products strictly, as some have at- tempted to do, into the excrementitious and the recrementitious ; that is, into those which are purely excretory in their character, and those which are subservient to further uses in the economy ; most, if not all of them, par- taking more or less of both characters. Still we may group the secreting processes for practical purposes, according to the predo' minance of one or other of the objects enu- merated above; those being arranged under the first division, in which the depuration of the blood is manifestly the chief end, any other being rendered subservient to this, as is the case pre-eminently w'ith regard to the urine ; those being classed under the second, in which the ulterior purpose of the separated fluid would seem to be the principal occasion of its production ; and this second group being subdivided, according as this ulterior purpose is connected with the operations of the economy itself, as is that of the tears, the saliva, the gastric fluids, &c., or is destined to act upon some other, as is the case with the milk, the odorous secretions, &c. F F 4f 440 SECRETION. Another classification has been proposed, of which the foundation is the degree of re- semblance of the secreted products to the normal constituents of the blood ; those being associated into one group, whose charac- teristic ingredients are altogether unlike those of the blood ; and a second group being formed of those, whose elements seem nearly alUed to those of the blood. This classification is practically almost the same with the pre- ceding ; for, as we shall hereafter see, all the cases in which the secreted products are very unlike the constituents of the blood, are those in which they are most directly and speedily removed from the body ; whilst those in which they serve some ulterior purpose, are for the most part also those, whose elements differ least from the components of the blood. The first group of these processes cor- responds with that which has been elsewhere treated of under the head of Excretion ; and the resultant products have been termed excrementitious secretions^ or more briefly ex- cretions y in contradistinction to the recremcn- titious secretionsy which are the products destined for ulterior uses. There is another group of processes, which corresponds so completely with the secreting operations in its general nature, that it is diffi- cult to avoid placing it under one category with them; the more especially, as the instruments by which it is effected correspond with the organs of secretion in the most essential fea- tures of their structure. We refer to that elaborating agency, which is now generally "believed to be exerted upon certain materials of the blood by the spleen, thymus, and thy- roid glands, and suprarenal capsules (which are sometimes collectively termed vascular glands), and also by the glands of the ab- sorbent system. The *' vascular glands," as will presently appear, exactly correspond with ordinary glands in all that part of their struc- ture by which they withdraw or eliminate certain mattei*s from the blood ; and they differ only in being unprovided with excretory ducts for the discharge of the product of their operation. These products, instead of being carried out of the body, are destined to be restored to the circulating current, apparently in a state of more complete adaptiveness to the wants of the nutritive function ; in other words, these vascular glands are concerned in the assimilation of the materials that are destined to be converted into organised tissues, instead of being the instruments of the re- moval of the matters which result from the disintegration or decay of those tissues. And in regard to the entire absorbent system, with its glandulae, reasons will be presently ad- vanced for regarding it all as one great secre- tory apparatus, whose relations are essentially antagonistic to those of the excreting appa- ratus ; the materials of its operation being de- rived from the external world, and its products being poured into the blood ; and its purpose being to supply fresh pabulum to the circu- lating fluid, whose effete matters are being drawn off" by the eliminating agency of other glands, whose products are carried back to the external world. The line of demarcation between the func- tions of nutrition and secretion can scarcely be drawn with definiteness ; so close is the affinity between the two sets of operations, both in their nature and in their purpose. For, as will presently appear, every act of true secretion is really a part of the nutritive pro- cess, the selection of the materials on which the secreting organ acts being effected by the development of certain groups of cells, which, during their short period of existence, form a part of the solid constituents of the body ; so that, as was first pointed out by Professor Goodsir, the functions of nutrition and secretion are essentially the same in their nature. In regard to the objects of the two functions, moreover, there is not that differ- ence which might at first sight appear ; for although the nisus of the nutritive functions is directed towards the increase and mainte- nance of the solid fabric, and that of the secreting operations to the removal of certain fluids from the circulating current, the reten- tion of which would be injurious, yet here again there is much common ground. For, as was first pointed out by Treviranus, " each single part of the body, in respect of its nu- trition, stands to the whole body in the rela- tion of an excreted substance;" in other words, every part of the body, by taking from the blood the peculiar substances which it needs for its own nutrition, does thereby act as an excretory organ, inasmuch as it removes from the blood that which, if retained in it, would be injurious to the nutrition of the rest of the body. Thus the phosphates which are deposited in our bones are as effectually ex- creted from the blood, and prevented from acting injuriously on the other tissues, as are those which are discharged in the urine. The application of this idea has been thus felicitously extended by Mr. Paget*: — " The influence of this principle may be considered in a large class of outward growing tissues. The hair, in its constant growth, serves, over and above its local purposes, for the advantage of the whole body ; in that, as it grows, it re- moves from the blood the bisulphide of pro- teine, and other constituents of its substance, w^hich are thus excreted from the body. Now this excretive office appears, in some in- stances, to be the only one by which the hair serves the purpose of the individual ; as, for example, in the foetus. Thus, in the foetus of the seal, and 1 believe of most other mammals, removed as they are from all those conditions against which hair protects, a perfect coat of hair is formed within the uterus, and very shortly after birth is shed, and replaced by another coat of wholly different colour, the growth of which had begnn within the uterus. Surely, in these cases, it is only as an ex- cretion, or chiefly as such, that this first growth of hair serves to the advantage of the * Lectures on Xutrition, Hypertrophy, and Atro- phy. Londoai Medical Gazette, ibi7. SECRETION. 441 individual. The lanugo of the human foetus is an homologous production, and must, I think, similarly serve in its economy, by re- moving from the blood, as so much excreted matter, the materials of which it is composed. " Now if this be reasonable, we may carry this principle to the apprehension of the true import of the hair, which exists in a kind of rudimental state on the general surface of our bodies, and to that of many other permanently rudimental organs, such as the mammary glands of the male and others. For these rudimental organs certainly do not serve, in a lower degree, the same purposes as are served by the homologous parts which are completely developed in other species, or in the other sex. To say they are useless, is contrary to all we know of the absolute perfection and all-pervading purpose of creation ; to say they exist merely for the sake of conformity with a general type of structure, is surely unphilo- sophical ; for the law of unity of organic types is, in larger instances, not observed, except when its observance contributes to the advan- tage of the individual. No ; all these rudi- mental organs must, as they grow, be excre- tions serving a definite purpose in the economy by removing their appropriate materials from the blood, and leaving it fitter for the nutrition of other parts, or adjusting the balance which might else be disturbed by the formation of some other part. Thus they minister to the self-interest of the individual ; while, as if for the sake of wonder, beauty, and perfect order, they are conformed with the great law of unity of organic types, and concur with the universal plan observed in the construction of organic beings." We cannot have a better example of the close affinity between the functions of nutri- tion and secretion, in regard alike to their essential nature and to their purpose, than that which is afforded by the structure, growth, and offices of the adipose tissue. Fat, wherever it exists, whether in large isolated masses, or dispersed through areolar tissue, is made up of an aggregation of minute cells, whose peculiar province it is to draw into themselves the superfluous oleaginous matter of the blood, as a part of the history of their own development. Since they form constituent parts of the organism, and may possess as great a duration as that of any other of the elements of the soft tissues of the body, the growth of fat cells is commonly regarded as an act of nutrition. But it may also be considered as an act of secretion ; for it is the means of separating from the blood a product which is not destined to undergo any further organisation, and whose accumulation in the circulating fluicl, beyond a very small and limited amount, would be positively noxious. This very same act of elimination of fatty matter, when performed by the cells of the liver, or of the sebaceous follicles of the skin, or (abnormally) by those of the kidney or of the intestinal glandulae, is recognised as forming part of the function of excretion, the difference being simply in the position and re- lations of the secreting cells. For whilst those of the glands are placed upon or near the free surfaces of follicles or ducts, and are destined from the first to a speedy exuviation, those of fat are woven up with areolar fibres and membranes, and form solid masses of tissue. A distinction might be drawn, on the ground that the contents of the fat cells are destined to be again taken into the circula- tion ; whilst those of glandular cells, having been once eliminated from the blood, are never to return to it. But this would not hold good ; for the fat cells appear to have an in- definite duration, the reception of their con- tents into the circulating current seeming entirely to depend upon the demand for these in the blood* ; and there is now sufficient evidence that a considerable part of the bile that has been secreted and poured into the intestinal canal is destined for re-absorption. And if we admit that the spleen, thymus and thyroid bodies, and supra-renal capsules, are to be regarded as possessing a glandular character, although the products of their elaboration are destined to be received back again into the current of the circulation, it is difficult to find a reason for the exclusion of a mass of adipose tissue from the same category. Of the organs of secretion. — In order that we may duly understand the real nature of the secreting process, as elucidated by recent discoveries, it is requisite that we should ex- amine into the nature of the instruments by which it is effected. There can scarcely be a more beautiful illustration of the doctrine that physiology is as capable as any other science of being reduced to general prin- ciples, and that these principles must, if valid, be of universal operation, than the fact that the process of secretion — common as it is in all its essential features to the animal and vegetable kingdoms — is everywhere per- formed by the same agenc}', namely, the de- velopment of simple cells, each possessing its own independent vitality ; these bodies form- ing the really operative part of every secreting * Ma}" not this re-entrance be governed simply by physical laws ? There can be no question that the chief purpose of fat is to serve as a store of combustible matter, for the maintenance of the heat of the body, when there is a deficiency of materials in the blood. A certain proportion of fatty matter (from 4 to 6 parts in 1000) seems normally to exist in the blood ; and this is usually rencAved from the food as rapidly as it is eliminated by the respiratory process, or by the nutrition of the nervous tissue. But if the supply be -Rithheld, a diminution of the quantity of oleaginous matter in the circulating cm-rent must rapidly take place ; and it is then that we find the contents of the fat-cells reabsorbed into the blood. It has been sho^Ani by Matteucci that oleaginous matter ynW pass through a membranous septum towards a slightly alkaline fluid, such as the blood ; and it does not seem difficult to understand, therefore, how the fat-cells should give up a portion of their contents when the alkalinity of the blood is no longer neutralised by the fatty matter which it normally contains, and how just that amount should pass back again, which is necessary to keep up the due proportion of fatty matter in the blood, and no more. SECRETION organ, however complex its structure may be. The progress of comparative anatomy has shown that neither the form nor the in- ternal arrangement of the parts of a gland could have any essential connection with the nature of its product (see Gland) ; since even those glands (the liver and the kidney, for example) in which there is the greatest complexity of structure, make their first appearance at the lower end of the animal series, as in the early embryo of the very highest, in the simplest possible form. Still something was wanting to prove that the structural elements immediately concerned are in all instances the same ; and there seemed no analogy whatever between the secreting membrane of the animal and the secreting cell of the plant. The doctrine was first propounded by Purkinje * and Schwann f, adopted and extended by Henle J, and fully confirmed by the researches of Goodsir^ and Bowman ||, that the true pro- cess of secretion — under whatever form it may present itself — is always performed by the intervention of cells; which, as part of their own regular vital actions, select and withdraw certain ingredients from the nu- tritive fluids, and afterwards set them free again, generally by the rupture or dissolution of the cell-wall, but sometimes perhaps by a simple act of transudation. For the proper comprehension of this doctrine in all its ge- nerality, it is necessary to give some attention to the history of cell-development, as mani- fested in the simplest forms of organic ex- istence ; those cryptogamic plants, namely, in which every cell is a distinct and inde- pendent individual. The earliest condition of such a cell is a minute molecide, which cannot be discerned except under a considerable magnifying power, and in which even the highest ampli- fication fails to exhibit any distinction of parts. When placed under circumstances favourable to its development, — namely, when supplied with the materials of its nu- trition, and stimulated by the requisite de- gree of warmth, — this germ increases in size; and a distinction becomes apparent between its transparent exterior and its coloured interior. Thus we have the first indication between the cell-wall and the celUcavity. As the en- largement proceeds, the distinction becomes more obvious ; the cell-wall is seen to be of extreme tenuity and perfectly transparent, and to be homogeneous in its texture, whilst the contents of the cavity are distinguishable in the Algae by their colour, which is green in the Chlorococciy and bright red in the Hcsma- tococci ; but in the simple fungi, such as the Torula cerevisiiy or yeast -plant, they are colourless. The contents of the cell-cavity * Isis, 1838, No. 7. f Froriep's Notizen, Feb. 1838. X Mtiller's Ai-chiv. 1838, p. 104—108 ; 1839, p. 45. § Trans, of Royal Society of Edinburgh, 1842. II Art. INIucous Membrane ; and Phil. Trans. 1842, " On the Structure and Uses of the Malpighian Bodies of the Kidney." have no relation whatever to the material of the cell. wall. Of this we have a remarkable example in the cases just cited ; for whilst the red and green coloured products of the Algae are probably nearly related to each other and to the chlorophyll of higher plants, being simple ternary compounds of water and carbon, the cell-contents of the yeast-plant are closely allied to the protein compounds ; and yet the cell- walls in both instances are composed of the same material, cellulose. It is evident, then, that the inherent powers of the cell are not confined to the application of nutrient materials to the extension of its own walls, and the consequent enlargement of its cavity ; but that they are exercised also in selecting from (and it maybe in combining or modifying) the same materials, in order to fill this cavity with a certain product, which may be altogether different in its constitution and its properties from that of which its wall is composed. This latter process is as essential to our idea of a living cell, as is the growth of its wall; and must never be left out of view when the history of cell-development is being considered. The nature of the compound thus stored up in the interior of a cell depends in part upon the original inherent endowments of the cell itself, derived from its germ ; and, in part, upon the character of the nutriment supplied to it. Thus we find that the simple Algae will grow wherever they can obtain, from the air and moisture around, the elements of their cell-walls and of their cell-contents ; which elements they have themselves the power of combining into those peculiar com- pounds, of which analysis shows that they are composed. But out of the very same materials, and under circumstances to all appearance identical, the Chlorococcus manu- factures a green product, and the Hsemato- coccus a red one. On the other hand the yeast-plant, like the fungi in general, will only grow where it meets with an azotised compound already formed ; and from this it elaborates the product which occupies its cell-cavity, its cell- wall being apparently formed by the same process as that of the simplest Algae. It could no more vege- tate, as they do, upon cold damp surfaces, than they could develop themselves in a solution of fermentible matter secluded from the light. A similar variety of function is seen amongst the cells, whose aggregation makes up the structure of any one of the higher plants, and which are all the descendants of the single cell which constituted its original germ. Thus we have in the green cells of the leaves the representatives of the simple Chlorococci ; these, under the influence of solar light, com- bining the carbon which they derive from the atmosphere, or from the soil, with the water transmitted from the roots, and elaborating these elements into a variety of new products, amongst which chlorophylf and cellulose are still pronainent ; but also operating upon the azote which they draw from the atmosphere SECRETION. 443 or from the soil, and combining this with the other three elements into quaternary com- pounds, that seem destined rather for the nutrition of animals than for any special pur- pose in the economy of the plant itself. The contents of the cells of the leaves are thus of a very complex nature ; their life not be- ginning and ending with themselves, as is the case with that of the independent organisms, which in other respects they resemble ; but having relations to the rest of the structure, for which, in fact, it is their function to pre- pare the pabulum. For the elaborated sap or nutritious fluid, which is the product of their agency, is transmitted through the entire fabric, and furnishes each portion with the materials of its development and extension, which in every instance is effected by an act of cell-growth. All parts select from it the same substance for the formation of the cell- walls, but the cell-contents are different in every organ and variety of tissue. Thus we find one set of cells drawing in starch, another fixed oil, another resin, another volatile oil, another colouring matter, another sclerogen, another protein compounds, and so on ; and this with the greatest uniformity and regu- larity. We may frequently see that even contiguous, and in other respects similar, cells, in the same organ, either select from the common pabulum a different compound, or exercise upon the same compound a dif- ferent influence. Thus we observe in the parti- coloured petal of a hearts-ease or tulip, certain stripes or patches of diflferent hues, which, when examined with the microscope, are found to consist of cells that differ from each other only in the colour of their contents. A precisely similar phenomenon is presented by the epidermic cells, which constitute the scales of the wings of Lepidoptera. In all these cases, however, the products which are separated from the circulating fluids are stored up within the component cells of the fabric, instead of being cast forth from it ; and although the term secretion is commonly applied to the process, yet it would be just as correct to regard it as part of the function of nutrition, it is, in fact, exactly on the same footing with the production of fat in animals. The absence of necessity for any other form of excretion in plants, than that which is carried on through the respiratory process, may be accounted for without much difficulty. A large proportion of the vegetable fabric is (from the nature of its chemical constitution) but little prone to decomposition, and pos- sesses a character so permanent, that it may remain almost unchanged for an indefinite time; and those parts which are of softer texture and more actively employed in the vital processes, and which are therefore more prone to decay, are periodically thrown off and renewed. In animals, on the other hand, all the softer tissues have a strong tendency to disintegration, in virtue of their peculiar composition ; and in some of them a destruc- tive chemical change seems to be the very condition of their functional activity. For the maintenance of their vital energy, theie- fore, there is needed not merely a constant supply of new material, but a continual re- moval of the effete particles. On this last operation, indeed, the continuance of the vital activity of animals is more closely and imme- diately dependent, than it is upon the supply of aliment ; for whilst the latter may be in- terrupted for a period of considerable dura- tion without producing more than debility, the former cannot be checked for many hours (in the warm-blooded animals at least) with- out a fatal result. Indeed, if we consider respiration as one of the excreting processes (which it undoubtedly is in a broad and philosophical acceptation of the latter term), we must say that tlie liberation of effete particles may not be suspended for more than a few minutes without death ensuing. Turning our attention, then, in the first instance, to the excretory organs of animals, we may define them to be groups of cells, placed on the free surface of a membrane, which is directly continuous with that of the exterior of the body, whilst its attached sur- face is in relation to the blood-vessels, &c. of the interior ; so that these cells, having grow^n and developed themselves at the expense of the materials supplied by the bloo;l, are either cast off entire and conveyed away, or give up their contents by the rupture or deliquescence of their walls ; the products which they have selected or eliminated being thus, in either case, entirely got rid of from the interior of the fabric. The disposition of the membrane on which the cells -lie, whether it be spread out on a plane surface, depressed into short rounded follicles, or extended into long and convoluted tubes, is a matter of secondary consequence ; nor is it of more importance whether the follicles be isolated, and discharge their contents by separate outlets, as those of the skin or mucous membrane {Jig. 307.), or whether they are aggregated in clusters, and Fig. 307. {Fig. 209. Vol. II.) Glandular follicles in ventriculus succenturiatm of Falcon and other birds. {After Milller.) SECRETION. open into a common channel, like those of the liver of the lobster or cray-fifeh {fg^ 308.) ; Fig. 308. {Fig. 2U. Vol. II.) Lobule of the liver of Astacus fiuviatilis. (^JFiiUer.') nor, again, whether the tubes are few and of great length, lying loose in the cavity of the body, and passing from one end of it to the other, like the biliary vessels of insects Fig. 309. {Fig. 431. Vol. II.) Alimentary canal of Pontia hrassica. (fg. 309.) ; or whether they are very nu- merous, of less proportional length, and aggre- gated in a compact mass, as in the kidney of the higher animals. In all instances, then, the excretory organ essentially consists of a limitary membrane, which forms part of the integument of the body, or of one of its involutions ; and of cells covering the free surface of that membrane, and, consequently, in direct relation with the external surface. Thus we have the hmitary membrane of the true skin, and of the mu- cous membrane of the alimentary canal which is directly continuous with it, sunk into follicular depressions ; and the tree surfaces of these are lined with cells, the layers of which are continuous with those of the epidermis and of the gastro-intestinal epithe- lium respectively. (See Mucous Membrane.) We trace inwards another extension of the same membrane along the genito-urinary passages, up to the -kidneys, where it form's the walls of the tubuU uriniferi ; and there, too, its free surface is covered with an epithelial layer of cells, which is the efficient instrument of the selection of the constituents of the lu-inary fluid, and which, when ex- uviated, is conveyed along the urinary- passages to the exterior of the body. So, too, the hepatic cells, by which the bihary matter is eliminated from the blood, are brought into direct continuity with those of the external surface, through the hepatic ducts and gastro- intestinal raucous membrane. The case is not different, in any essential respect, with regard to the organs by which the recrementitious secretions are formed. Thus the lachrymal, salivary, pancreatic, and mammary glands are in like manner composed of a continuation of the limitary membrane of the true skin, or of the mucous membrane lining the alimentary canal, involuted into tubes and follicles, the free surfaces of which are covered with epithehal cells. These cells, drawing into themselves certain constituents of the blood, are cast off when they have completed their full development ; and their contents, set free by the disintegration of the cell-walls, are carried off by the ducts, which collect them from different portions of the glandular structure, and deposit them in the situation where the purposes of the secreted product are to be answered. If we attentively consider the character of what is commonly designated as the absorbent system, we shall see that this, too, may be re- garded as a glandular apparatus ; possessing, as it does, the essential characters of a gland in regard to its structure, and being analogous to the true glands in its mode of performing its function, and the difference of its purpose in the general economy being accordant with the difference of its anatomical relation. Putting out of view for the time the absorbent glands, or ganglia, we find the absorbent system to consist of two series of long tubuli, one set ex- tended through almost the entire body, whilst the other is distributed upon the intestinal canal. These tubes appear to commence either in cEecal origins or in loops ; they coalesce with each other; and at last dis- charge themselves into a common receptacle, just as do the tubuli of the kidney. That their origins should be widely scattered, in- stead of being bound together in one compact mass, is a fact of no physiological importance ; having reference only to the remoteness of the sources, whence are derived the materials on which the particular agency of this appara- tus is exerted. These materials are of two kinds ; for they consist in part of the crude materials selected by the lacteal division of the system from the contents of the ahment- ary tube, over whose walls the origins of the SECRETION. 445 lacteals are dispersed; and in part of substances taken up by the lymphatic or interstitial divi- sion, and probably consisting chiefly of par- ticles which are 'set free by the continual disintegration of the living structure, but which, not being yet decomposed, are capable of being again employed for the purposes of nutrition. The materials derived from these sources appear to require a considerable pre- paration or elaboration, before they are fit to be introduced into the current of the circula- tion ; and this elaboration is effected by an agency of precisely the same nature with that which is concerned in the removal of various products of secretion from the blood ; for the tubuli of the absorbent system, like those of the kidney or the testis, are hned by epithe- lial cells, and their duty seems to be altogether analogous. The alterations which the ab- sorbed matters undergo during their passage along this system of tubes, and the evidence thatlhese alterations are in great part due to the elaborating action of cells, having been heretofore considered (^see Nutrition), need not be again dwelt on ; but a few words may be added respecting the structure and func- tions of the glandulag or ganglia, with which the absorbent vessels of man and the mam- malia are copiously furnished. These bodies are composed of lacteal or lymphatic trunks, convoluted into knots, and distended into cavities of variable form and size, which are known as the "cells" of these glands. Amongst these cells there is a copious plexus of blood-vessels, but there is no direct com- munication between their cavities. Accord- ing to Prof. Goodsir *, the epithelium which lines the absorbent vessel undergoes a marked change where the vessel enters a gland, and becomes more like that of the proper glandu- lar follicles in its character. Instead of being flat and scale-like, and forming a single layer in close apposition with the basement mem- brane (as it does in the lacteal tubes before they enter the gland, and after they have emerged from it), we find it composed, within the gland, of numerous layers of spherical nucleated cells, of which the superficial ones are easily detached, and which appear to be identical' with the cells that are found floating in the chyle and lymph, especially after their passage through these bodies. The absorbent glands may be regarded, therefore, as concen- trating within themselves that agency, to which the whole system of tubuU is more or less subservient. Such an idea is strictly ac- cordant with the facts of comparative anatomy; for in reptiles, in which there are no glands, the tubuli or vessels are enormously length- ened by the convolutions which they present along their course, as if to furnish a suffi- cient extent of epithelial surface. There is strong reason for regarding the spleen, the thymus and thyroid glands, and the supra-renal capsules, as parts of the same assimilative apparatus, their office apparently * Anatomical and Pathological Obsen^ation r. 4G. being, to withdraw certain crude matters from the blood, to submit these to an elaborating action whereby they shall be rendered more fit for the nutrition of the tissues, and then to restore them to the circulating current. The details of the structure of these organs will be found under their respective names ; and it will be sufficient to state here, that they all show an essential correspondence with the true and recognised glands in every respect but this, that they have no eflf'erent ducts. Each of them may be described as consisting essentially of a number of vesicles, which are either closed and isolated, or open into a common reservoir, which is itself closed ; the vesicles in either case are lined with epithelial cells.* Around these, as around the follicles or tubuli of the true glands, blood-vessels are copiously distributed ; and the elimination of products from the blood appears to be effected by their agency, precisely as if these products were destined to be cast out of the body. The mode in which they are taken back into the circulation, after they have been subjected to the elaborating process, is not very clear ; both blood-vessels and absorbents have been supposed to participate in the operation ; and this idea may not be regarded as improbable, v^hen the large size and number of the lymphatics distributed to these organs is considered. Having thus taken a general survey of the principal varieties of secretory structure, and of the chief aspects under w^hich the secreting function presents itself, we shall pass on to a more particular consideration of the mode in which this operation is performed, and of the instruments by w^hich it is effected. For this purpose it will be preferable to select a par- ticular gland, and to examine the minutiae of its structure in the most diverse forms and conditions under which it presents itself ; and there is none which suits our purpose so well as the liver, which is the gland of most universal existence throughout the whole animal series, and which presents almost every leading variety that is found in the whole series of glandular structures. And we gladly avail ourselves of the opportunity thus afforded, of bringing the account already given of that gland (see Liver) into con- formity with the increased knowledge of its structure that has been since acquired. There are few animals possessed of a dis- tinct digestive cavity, in which some traces of a biliary apparatus (recognisable by the colour of the secretion) may not be distinguished. Thus in the Hi/cb-a, some of the cells that form the lining of the stomach contain a brownish-yellow matter, strongly resembhng bile, which is probably poured into the cavity on the rupture of the cells. In the walls of the stomach of the Actinia^ Dr. Thomas Wil- liams has described sulci formed by duplicatures of the lining membrane, in which are lodged a set of cells of glandular appearance, some *■ See Prof. Ecker, in Annales des Sciences Na- turelles, Zoologie, Aout, 1847. 446 SECRETION. of them containing scarlet-red, and others bright yellow granules ; the latter are regarded by Dr. VV., and probably with justice, as the diffused rudiments of a liver.* In the Bower- hankia densa, and in other Bryozoa, very distinct spots may be seen in the parietes of the stomach, which seem to be composed of clusters of biliary cells contained within fol- licles ; and during digestion, the contents of the stomach are seen to be tinged with a rich yellow-brown hue, derived from the matter discharged from these follicles.f In the Asterias the digestive cavity is surrounded by a more complicated glandular apparatus, but it seems difficult to determine the precise portion of this which discharges the function of a liver. The central stomach is furnished with a pair of glandular appendages, each composed of a cluster of follicles, which open into its fundus ; and these, from their dull yellow colour, have been thought to be a liver. Dr. Williams states, however (loc. cit.), that their ultimate structure does not sanction that idea, the terminal vesicles abounding in a white elastic tissue, in the meshes of which are entangled a number of small, compact, and granular cells, which are by no means hepatic in their aspect. He is disposed to agree with Dr. Grant, who hints that this organ may be a rudimentary pan- creas ; we should, ourselves, regard it as more probably a salivary gland, its secretion being apparently mingled with the food immediately upon the ingestion of the latter. In the walls of this central stomach, proper gastric follicles have been detected by Dr. Williams; and he regards in the light of an hepatic organ the dilated culs-de-sac, filled with large glan- dular cells, which are disposed in great num- bers along the ramifying caecal prolongations of the central stomach that are extended into the rays. In the lower groups of the Articulated series, we meet with a diffused form of the biliary apparatus, not unlike that which has been just described in the lower Radiata. Thus in the Earthworm, the large annulated alimentary canal is completely encased in a flocculent external coating, which, when exa- mined with the microscope, is found to consist of a mass of minute flask-shaped follicles, held by tubular peduncles, several of which coalesce to form the excretory canals for the discharge of the secretion into the digestive cavity. These follicles are composed of a membrane of extreme tenuity, and their inte- rior is filled with cells containing granular matter and oil globules, which are the consti- tuents of the hepatic secretion. In the Leech and some other Annehda, the alimentary canal is furnished with large sacculated appendages ; and in the walls of these, as well as of the central canal, the bifiary cells are closely dis- posed. These cells, according to Dr. Wil- liams, are not included within follicles, as in the earthworm ; the absence of caecal multi- * Guy's Hospital Reports, 1846, p. 280. t Dr. A. Farre, in Phil. Trans. 1837. plications of the stomach in the latter being compensated by a concentration of parts in Fig. 310. {Fig. 69. Vol. 1.) Alimentary canal of Leech, with ccecal prolongations. the biliary system. In the Myrapoda, there is a decided advance from this difJused form of hepatic structure, towards that more con- centrated and isolated condition, in which we find the liver of Lisects. The general distri- bution of the biliary organs in this class has already been described. (See Insects, Vol. II. p. 974.) They consist of a number of dis- tinct filiform tubes, usually of a yellowish- brown colour, placed in close apposition to the sides of the alimentary canal, and opening into it near the pyloric extremity of the stomach, usually by separate orifices, but sometimes after the junction of two or more with each other, to form short common trunks. Their number varies considerably; the fewest, namely four, existing in the Dij)- tera, six being found in the Lepidoptera^ and many more in the Orthoptera and Hymenop- tera. When few in number, they are very long, sometimes three or four times the length of the alimentary canal, and are tortuous and convoluted ; when numerous, they are pro- portionally short, and are more delicate in structure. In many larvae, they are furnished with lateral caeca, but these almost always disappear as the insect approaches the imago state. The following is the description re- cently given of the minute structure of the biliary tubuh, by a well qualified observer : — " When more intimately examined, these tubes are found to consist of a delicate tube of clear, transparent, amorphous basement membrane, the inner surface of which is co- vered with secreting cells. From the thin- ness of the tube, the cells often project, so as to give it a granulated appearance when SECRETION. 447 viewed by the naked eye, as in the flesh-fly, Musca carnaria {fig. 31 1. a, 6) ; and generally F^. 311. Biliary Organs of Musca carnaria. a, portion of a trunk and two branches of one of the bihary tubes of the flesh -fly, xaewed by re- flected light, and magnified eight diameters ; h, portion of a biliary tube of the flesh-fly highly magnified, exhibiting the arrangement of the se- creting cells, and the mode of distribution of the tracheas ; c, a secreting cell from the liver of the flesh-fly, very highly magnified. {After Leidi/.) towards the free extremities the sides of the tubes are so irregular, that they appear as if merely folded upon the secreting cells to keep them together. The secreting cells are round, oval, or nearly cylindrical from elongation. Their average measurement is about '09 millhn. The contents are white, yellowish, or brownish, and consist of a finely granular matter, numerous fine oil globules, a granular nucleus, and a transparent nucleolus. The cells in the extremity of the tubes are not more than half the size of those a little further on (or nearer the termination), and contain less granular matter and no oil globules, so that they are more distinct, and the nucleus more apparent. Upon advancing a very little, the cells are found to be of an increased size, and full of granular matter, so as considerably to obscure the nucleus from view. A little further, we find the addition of fine oil globules, readily distinguishable by their thick, black outUne when viewed in a certain focus. Sometimes the cells become so filled with oil, as to be distended with it, rendering the granular matter and nucleus so transparent as totally to destroy all appearance of the for- mer, and the latter only is to be perceived in faint outline. Such a state I have frequently observed in Dermestes, Ateuchus, &c. The nucleus (fig. 31 1, c) is generally central, glo- bular, and pretty uniform in size in the same species, averaging in measurement about *025 millim. The nucleolus is always transparent, and measures about '006 millim. The cen- tral passage of the tubes, or separation of the cells in the middle line, is usually found filled with fine granules, and a great amount of oil globules. The biliary tubes of insects are bathed in blood, or the nutritive fluid, and the respiratory tracheae are distributed to them with extreme minuteness, but are separated from the secreting cells by the intervention of the basement membrane."* According to Dr. T. WilUams (op. cit.), some at least of the large cells which give the sacculated ap- pearance to a biliary tubulus are really parent cells, filled with a second generation of hepa- tic cells ; they are, therefore, analogous to fol- licles, save that they have no proper outlet, for we shall hereafter see that the follicle in its earliest condition is probably nothing else than a parent cell. From the above descrip- tion, it would appear that the hepatic cells originate towards the upper or caecal end of the tubulus, that they are gradually being pushed onwards towards the outlet by the growth of new generations behind them ; and that, as they thus advance, they acquire an increase in size by their own inherent powers of development, at the same time drawing into themselves the peculiar matters which they are destined to eliminate from the circu- lating fluids. The ceils, having attained their full growth, and completed their term of life, give up their contents by the rupture or deli- quescence of their walls, and these pass down the central cavity of the tube, to be discharged into the alimentary canal. In the higher Crustacea we find a condition of biliary structure much more closely allied to that of MoUusca than to that of Insects ; the Hver being a pair of massive lobulated bodies, each of them made up by the aggre- gation of numerous caecal follicles, from every one of which passes off a narrow duct, to join a trunk that is common to all the vesicles on one side. " In structure," says Dr. Leidy (loc. cit.), ** the caeca resemble the tubes of insects, being composed of a sac of basement membrane, within which, originating from the inner surface, are numerous secreting cells {fig. 312. a). The cells are more or less polygonal in form, from mutual pressure. At the bottom of the caeca the cells are small, with an average diameter of 02 millim., and contain a finely granular matter of yellowish hue, with a granular nucleus, and a trans- parent nucleolus. As we proceed from the bottom upwards, the cells {f,e,d,c, i) are found to increase in size, and to obtain a gra- dual addition of oil globules, until beyond the middle of the tube, where they are found filled with oil, so as to have the appearance of ordinary fat cells, and have a diameter avera- ging '06 millim. From this arrangement of the cells, when a caecum is viewed beneath the microscope, its lower half appears filled * Leidy, in American Journal of the Medical Sciences for Jan. 1848. 448 SECRETION. with a finely granular matter, intermingled with nucleoio-nucleated bodies, and the an- Fig. 312. Biliary Organs of Artacus affinis. a, cjBcum of the liver of Cray-fish, with its contained cells ; h, c, d, e, /exhibit the progressive changes of the cells, as they advance fi-om the bottom of the tube. ( After Lddy. ) terior half with a mass of fat cells, the nucleus hardly visible, from the property of oil ren- dering organic tissues more or less trans- parent. The central cavity of the caeca is filled with fat globules, and' a finely granular matter corresponding to that in the interior of the cells." In some of the lower forms of Crustacea, the liver is reduced to the simple condition which it presents in insects ; and there is one very curious group, that of Pyc- nogonidcB, in which the biliary apparatus is as much diffused as in the Radiata. In these animals, the stomach sends caecal prolonga- tions into the legs, and these extend nearly to their terminal claws. The walls, both of the central stomach and of its tubular exten- sions, are studded with brownish -yellow cells ; but beyond this there is no rudiment of any organ for the secretion of bile. In the MoUuscous animals, the general structure of the liver closely corresponds with that which has just been described in the higher Crustacea. Among the Compound Tunicata, however, to which the Bryozoa are so nearly related that many naturahsts asso- ciate them together in one group, the struc- ture of the liver is the same as that of Bower- bankia; the hepatic follicles being isolated from each other, and lodged in the walls of the stomach, into the cavity of which they pour their secretion by separate orifices. In the Solitary Ascid'ians, the hepatic follicles are more developed, and cluster round the ex- terior of the stomach, so as to give it a shaggy appearance, very much as in the earthworm. In the Conchifera, the liver presents itself as a distinct organ, composed of numerous lobules ; each of these is made up of a cluster of tubes, terminating at one extremity in flask-shaped follicles, whilst at the other they coalesce into a few larger trunks, which discharge themselves into the digestive ca^'ity. The follicles are filled with cells containing the bihary secretion. The structure is nearly the same in the Gasteropoda ; the ducts of the several lobules coalescing, so as to form two main trunks, by which the secretion is poured into the duodenum. The folio wing is Dr. Leidy's account of the minute structure of the liver of the snail ; a portion of which, moderately en- larged, and showing the arrangement of the lobules, is shown in fig. 313. a. *' When one Fig. 313. Biliary Organs of HeUx alholabris. a, portion of the liver of the snail, moderately mag- nified, exhibiting the arrangement of the lobules ; b, a biliary c£ecum from the same liver, highly magnified. of the bulbiform caeca (fig. 313. b) is examined beneath the microscope, it is found to have a structure differing in no important particulars from that of the cray-fish. The cells at the bottom cf the sac (fig. 314. a, I, 2) average SECRETION. 449 •02 millim. in diameter ; those towards the other extremity about ^04 millim. Some of Fig, 314. Hepatic cells of Helix alholahris, a, 1, 2, two cells from the bottom of the caecum ; 6, 1, 2, two cells more advanced, containing nu- merous oil globules ; c, 1, 2, 3, three cells, con- taining larger oil globules; d, a cell distended with oil; e, a cell containing nothing but six deep yellow consistent oil globules ; f, a cell con- taining a hard yellow mass of fat ; g, a cell rup- turing, and its contents escaping ; A, nuclei of hepatic cells, highly magnified. the fully ripe cells (6, 1, 2) are filled with innumerable minute globules of oil, hardly distinguishable from the granular matter ; others (c, 1, 2, 3) with globules of a larger size ; some are found with from one to ten or more large, deep yellow, oil globules in the centre ; a few (/) with a hard or crystallised mass of fat in the centre ; and many (d ) are distended with oil. By pressing the cells (g) between two plates of glass, the contents will be squeezed out, and the structure will be seen as follows : — the vesicular transparent, amorphous cell-wall, finely granular matter, fat globules, and a granular nucleus (h), mea- suring about '01 millim. and containing a hard transparent nucleolus. A few of the cells contain two nuclei. The blood-vessels, con- sisting of arteries and veins, form a rete around the bulbiform caeca, but do not appear to come in immediate contact with the secreting cells " (loc. cit.). The general plan of struc- ture of the liver of the Cephalopoda is essen- tially the same ; the hepatic ducts and follicles being clustered as in a raceme, and the follicles being crowded with biliary cells. In the LoligOy these follicles are described by Dr. Williams (op. cit.), as being themselves sac- culated, by duplications of their membrane ; and some of the biliary cells appear as if pro- ducing a new generation within themselves. A very remarkable departure from the general type is presented by certain of the Nudibranckiate Mollusca, of which Eolis may be taken as the type. In these animals, the VQL. IV. stomach gives off on either side a number of branches, which usually redivide, and then Fig. 315. Eolis Farrani, showing the branchial papilla;. (^After Alder and Hancock.') give off smaller tubes, which are contirnied into the branchial papillae that cover the dor- sal surface (^g. 315.). "The prolongations of the branches that enter the papillae undergo a considerable enlargement and change of form ; and from the variety and brilliancy of their colouring are the chief attraction of these elegant little animals. The simplest form of this peculiar organ is met with in Eulis concinna, where it is a mere dilated tube, having its walls slightly waved, and the inner surface sprinkled with darkish granules. In E. Farrani {Jig. 316. b) it still retains a con- siderable simplicity of structure, but becomes decidedly sacculated. The complexity is much increased in E. olivacea, in which it is produced into puckered follicles or sacculi ; but in E. papulosa (Jiq. 316. a) it appears to attain its highest development. The central canal is there somewhat tortuous, and gives off on all sides variously sized, irregular, blind sacs, which are crowded with little conipound follicles. The whole of the inner surface is lined with a thickish layer of irregular vesicles or globules, filled with numerous granules. These last, when submitted to a high magni- fying power, are seen to be of various sizes, transparent, rounded, and nucleated. The whole of the internal surface of the gland is covered with vibratile cilia. These compound glands are evidently biliart/ organs, diffused throughout the several papillae, and supplying the place of a compact liver, Avhich is wanting in the body of these animals. The stomach G G 450 SECRETION. and biliary organs are so intimately connected in this genus, that it is not easy to point out Biliary apparatus of Eolis. A, branchial papilla of E. papillosa, exhibiting the gland h and the duct c ; also an ovate vesicle, a, apparently an organ of defence, and at d the wall of the inner sheath; b, branchial papilla of E. Farrani, showing the same parts. {After Alder and Hancock.^ the limits of each ; they appear to differ in different species. In E. papillosa, the central canal is evidently a continuation of the sto- mach, and the plicated internal membrane is not only continuous throughout it, but also passes into the lateral branches, which thus appear to form part of the same organ. On the other hand, we find in some species coloured granules, similar to those of the papillae, partially lining the ramifications, as in E. gracilis and others ; while in E. despecta, the central canal, all the ramifications, and the glands of the papillae, are coloured and gra- nulated alike, implying a greater diffusion of the biliary function. The food, after being partially digested in the stomachal pouch, is driven in detached portions through the alimentary system, by the alternate contrac- tions of the pouch and great trunks leading from it ; these contractions are only of a nature to produce an oscillatory motion, which serves to promote that intimate mixture of the alimentary matters with the hepatic and other secretions, necessary to the process of digestion."'* The intimate structure of the liver of Ver- * Alder and Hancock's Nudibranchiate Mollusca, Part tehrated aninials is much more difficult of elucidation, and can scarcely be said to be yet satisfactorily determined. The organ presents more and more, as we ascend the seiies, a solid parenchymatous texture, which strikingly contrasts with its loosely lobulated racemose aspect, even in the highest Invertebrata. There is not the least difficulty in demon- strating that this parenchyma is composed of cells, which correspond in the nature of their contents, and, therefore, in their functional character, with those contained within the hepatic follicles of the Invertebrata ; but the point of obscurity is the relation of these cells to the biliary ducts, the arrangement of whose ultimate ramifications has been rather a matter of surmise and inference, than of actual obser- vation. It is very interesting to find, however, that in the lowest known Vertebrate the liver exists under the same rudimental and diffused type, as that which it exhibits in the lower Arti- culata. In the Amphioxus, or lancelet, the only vestige of a distinct hepatic organ is a large caecum prolonged from the stomach, which is lined with greenish-yellow cells. But it is pointed out by Miiller, that the intestinal canal itself has a layer of similar cells in its walls, so that the organ would seem to have the same diffused condition as that which it presents in the earth-worm. In all other fishes, however, the liver is a well-defined conglomerate gland, even the Myxinoids presenting a liver nearly as fully developed as that of the higher fishes, so that there is not here any such complete gradation as we usu- ally meet elsewhere. Dr. T. Williams states that he has succeeded in tracing the ducts to their ultimate terminations in the fiver of the Sole (Solea vulgaris), and the Flounder (Pla- tcssa fiexus) ; and he describes them as rami- fying like those of the Mollusca, and as ending in tubular caeca, without vesicular expansions. Within these caeca are found the hepatic cells, which usually, as in the Invertebrata, contain a large quantity of fat.* There is a remarkable diminution in the proportion of the adipose contents of the hepatic cells, and an increase in the granular constituents, in the class of Reptiles ; and in Birds there is an almost total absence of adipose particles. The ultimate distribution of the bile-ducts, and their relation to the parenchyma, seem to be the same as in the Mammalia. In the Mammalia, the liver is more or less distinctly divisible into minute lobules, each of them composed of a parenchyma of hepatic cells, through which the blood-vessels are dis- tributed in a close and solid plexus. The hepatic cells appear to occupy the entire space left in the meshes of this plexus, the bile- ducts having been usually regarded as not traceable, under any form, into the interior of the lobule. Mr. Kiernan, however, has always regarded the bile-ducts as forming a plexus in the substance of the lobule, interlacing with the plexus of capillaries ; his belief being chiefly founded on the anastomotic distribu- * Guy's Hospital Reports, 18i6, p. 323. SECRETION. 451 tion of the bile-ducts in the left lateral liga- ment, which he considers as in itself a rudi- mental liver, exhibiting the structure of the entire organ in its most simple form . By Mr. Bowman it was supposed, that the limitary membrane forming the wall of the minute biliary ducts is not continued into the sub- stance of the lobule, but that the epithelial lining of the ducts is continuous with the mass of hepatic cells which forms its parenchyma. There is an a priori improbability in such an idea, which would leave the glandular cells in immediate 'contact with the surface of the blood-vessels ; an arrangement which does not exist in any other gland. We have been accustomed, therefore, to accord with the opinion of Dr. Thomas Williams*, that the limitary membrane of the bile-ducts is pro- bably expanded over the whole of the paren- chymatous portion of each lobule, moulding itself upon, and identifying itself with, the capsule or sheath of the vessels, and thus forming a sort of irregularly reticulated cavity, which may be described as the whole space occupied by the lobule, minus the series of passages containing the capillary plexus. The manner in which the lining membrane of the uterine sinuses with the cellular decidua are prolonged into the placenta, and reflected over the capillary tufts of the foetal vessels, so as to divide the whole cavity of the placenta into a series of irregularly shaped chambers, freely communicating with each other, into which the maternal blood is conveyed, will convey an idea of this method of viewing the disposition of parts in the liver ; the uterine sinuses representing the bile-ducts ; thecellated cavities of the placenta, corresponding with the spaces occupied by the cells of the hepatic parenchyma ; and the foetal vessels occupying Fig. 317. Biliary plexus in human Liver. Transverse section of a lobiJe of the human liver' highly magnified, shoAving the reticulate struc- ture of the biliary tubes. In the centre of the figure is seen the hepatic vein cut across, and several small branches terminating in it. At the periphery are seen branches of the hepatic artery, vena portae, and hepatic duct. {After Leidy.) * Op. cit. p. 330. the place of the capillary plexus from which the secretion is formed. The observations recently published by Dr. Leidy harmonise precisely with the view pro- mulgated by Mr. Kiernan, and seem to confirm the idea that here, as elsewhere, the hepatic cells are enclosed in a limitary membrane. " The lobules are composed of an intertexture of biliary tubes {fg. 317.) ; and in the inter- spaces of the network the blood-vessels ramify and form among themselves an intricate anastomosis, the whole being intimately con- nected together by a combination of the white fibrous and the yellow elastic tissue. In Fig. 313. Biliary plexus in h uman Liver. A small portion of the same section more highly magnified. The secreting cells are seen within the tubes ; and in the interspaces of the latter, the fibrous tissue is represented. (After Leidy.') Structure, the biliary tubes (^^5. 3 18, 3 19.) cor- respond with those of Invertebrata, consisting Fig. 319. Biliary tubulus of human Liver. Portion of a biliary tube from a fresh human liver, very highly magnified. The secreting cells are seen to be polvgonal from mutual pressure. (After Leidy.) of cylinders of basement membrane, containing numerous secreting cells, and the only differ- ence exists in the arrangement, tlie free tubes of the lower animals becoming anasto- mosed on forming an intertexture in the Ver- tebrata. The tubuli vary in size in an un- important degree in different animals, and also in the same animal, being generally from two G G 2 452 SECRETION. to two and a half times the diameter of the secreting cells. The tubes of one lobule are distinct from those of the neighbouring lobuli, or only communicate indirectly by means of the trunks or hepatic ducts, originating from the tubes, and lying in the interspaces of the lobuh. The secreting cells (fig. 320.) are irre- gularly angular or polygonal in form, from mutual pressure, and line the interior surface of the tubes. They vary in size in a moderate degree in different animals, and also in the same animal, appearing to depend upon cer- tain conditions of the animal and liver."* We have ourselves verified these important observations to a certain point, not having been able to obtain a view of the regular and complete plexus of ducts figured and described by Dr.Leidy,but having satisfied ourselves that a system of canals, prolonged from the bile- ducts, exists in each lobule. The recently published observations of Dr.Natalis Guillotf are to the same effect. He has not been able, any more than ourselves, to distinguish mem- branous parietes around these canals ; and he considers that they are simply channelled out in the parenchyma of the liver, the particles of which form its sole borders. It appears probable to us, however, that these canals correspond to the spaces left in the centre of the biliary tubuli of insects, &c. ; and that the membranous walls, if they exist at all, would be found to invest the cells which immediately bound these passages. The biliary cells of the Mammalia (fig. 520.) usually contain a certain number of adipose particles ; their size and number, however, vary considerably according to the food of the animal, the amount of exercise which it has been taking, and other circumstances. If an animal be very fat or well fed, especi- Fig. 320. Hepatic cells of human Liver. a, three secreting cells of ordinary aspect ; b, a secreting cell much more highly magnified, show- ing the central nucleus, granular particles, and oil globules ; c, four secreting cells from a human liver in a state of fatty degeneration, showing a great increase of oil globules. ( After Leidy.) ally with farinaceous or oleaginous substances, the proportion of adipose particles is much greater than in an animal moderately fed and taking much exercise. The size of the glo- bules varies from that of mere points, scarcely distinguishable from the granular contents of the cells but by their intense blackness, up to one-fourth of the diameter of the cell. The finely granular matter is the portion from which the colour of the cell is derived ; it seems to fill the space not occupied by the oil globules ; and it often obscures the nu- cleus, so that the latter cannot be distinguished until acetic acid is added, which makes the granular matter more transparent without affecting the nucleus. The following are the dimensions of the hepatic cells in various animals, according to the measurements of Dr. Leidy (loc. cit.). Long Diam. Short Diam. Nucleus. Centipede (Jul us impressus^ Millim. Millim. Millim. •0125 Tumble bug (Ateuchus volvens) •0225 •0125 Katydid (Platyphyllum concavwn) - •13 •0225 House-fly (Musca domestica) - - - •09 •06 •0225 Flesh-fly (3fusca carnaria) - - - •00 •0275 Cray-fish (Astacus affi.nis') - - - •OG to -02 •015 Snail {Helix albolahris) - - - •04 to ^02 Slug (Limax variegatus^ .. _ _ •OG to ^03 Rock-fish {Labrax lineatus) - - - •0275 Minnow (Hydrargira ornata^ •02 •015 Cat-fish (Pimelodus catus) - - . •0275 Lizard {Triton niger) - .. - _ •03 •0125 Frog (Rana halecina) - _ _ - •03 •02 •005 to •Ol Terrapin (Einys Terrapin) - - - •03 Snake (Tropinodotus sirtalis) - •02 to -0275 Boa {Boa constrictor) - - - - •03 •015 Duck {Anas acuta) - - - - Owl {Strix braclujotos) - - - - •0175 to ^02 •006 •015 •005 Chi?ken ( Gallus domesticus) - - - •016 Ground Squirrel (Sciurus striatus) - •0175 Gray Squirrel (Sciurus Carolinensis) •015 Eabbit {Lepus Americanus) - - - •03 to •Olo •01 Sloth {Bradypus tridactylus) - - - •0133 Leopard {Felis leopardus) - - _ •0125 to -015 Monkey ( iSmm ?) - - - •015 •03 to ^015 •02 •009 * See American Journal of the Medical Sciences, of injected liver, then to make as thin a slice of this Jan. 1848. Dr. Leidy does not specify the mode in as possible, and to examine this slice when restored which his preparations have been made; but Ave to its original condition by moisture, understand that his plan is to dry a small portion Annales des Sciences Naturelles, Mars, 1848. SECRETION. 4o3 When the foregoing facts are duly weighed, the conclusion seems irresistible, that the cells containing the biliary matter are the only in- variable constituents of the hepatic a|)pa- ratus ; and that the manner in which these cells are arranged, and brought into relation with the blood-vessels, may vary indefinitely without producing any change in the charac- ter of the product. Consequently we cannot but look upon the biliary cells as the essential portion of the secreting structure ; and we must, in like manner, consider their agency as the essential part of the secretory function. The same result has been obtained in all other cases in which the character of the se- creted product is such, that it can be de- tected, when in a finely divided state, by the assistance of the microscope. Thus Prof. Goodsir has shown* that the pigmentary matter of the "ink" of the cuttle-fish is con- tained within the cells that Hue the ink-bag ; that the purple fluid secreted from the edge and internal surface of tiie mantle of lanth'ina fragUls (which is supposed to have furnished the Tyrian dye) is contained within a layer of nucleated cells situated on the secreting surface ; and that a fluid resembling milk may be found in the cells contained within the ultimate follicles of the mammary gland in a lactating animal. We seem perfectly justified in concluding, therefore, that in cases where the transparency and freedom from colour of the secreted product prevent our distinguish- ing it in the cells of the organ by which it is eliminated (as in the case of the urine), it is nevertheless contained within them and eli- minated by their agency. It would probably be too much to affirm, that the elimination of the secretion always involves the Q.c>x\\\x\vvdX exuviation of the cells, which are the instruments of the process. On the con- trary, it seems probable that where the solid matter of the secretion bears but a small pro- portion to the liquid, and is in a state of per- fect solution, the secreting cells ma}- be con- tinually drawing in their peculiar pabulum on the side nearest to the capillary network, and may be as constantly allowing it to transude by the free surface, so as to permit its pas- sage into the cavity of the tube or follicle, — the cells themselves remaining attached to its walls, and continuing to perform this function f<)r a considerable time. Such is probably the case with regard to the epithelial cells which line the tubuli of the kidney, and which eli- minate the secretion of urine ; and those which line the tubes of the perspiratory glan- dule are probably as permanent. In the case of cells, however, whose secre- tion contains a large quantity of solid matter, and especially where this is of an adipose character, it seems impossible to suppose that their contents can be given up, without the rupture or deliquescence of the cell-walls. This may take place either whilst the cells are yet in the follicles within which they were generated, or after they have been ca^t entire * Trans, of Royal Society of Edmburgb, 1842. into the ducts, or have been even conveyed through them to their outlet. We have seen that in the biliary follicles of the Invertebrata, the discharged contents of secreting cells are usually to be met with, indicating that this rupture or deliquescence has taken place with- in the follicles ; and this is probably the fiict in regard to the biliary cells in general. An extreme case of another kind is furnished by Mr. Harry Goodsir, in regard to the cells of an organ which is essentially one of secretion as to its structure, though its function has a different direction ; the peculiarity of this case being, that even after the complete exuviation of the cells, they retain so much of inde- pendent vitality, as to proceed in their own development to a stage much beyond that at which they were set Iree. The case referred to is that of the seminal secretion of the deca- podous crustaceans ; the cells of which, when thrown out of the caeca of the testis, are very imn)ature, and undergo important changes in their progress along the tubuli of that gland. The final changes, however, whereby they are fitted for the fertilisation of the ova, only take place after they have been discharged from the male organs, and have been lodged in the spermotheca of the female.* Now in every case in which the secreted product can only be given up by the rupture or solution of the cell-wall, it is obvious that there must be a continual succession or new production of the secreting cells ; and a ques- tion naturally arises as to their origin and mode of development. Few facts are as yet known upon this subject. It may, however, be stated with some certainty, that, in many of the simpler glands at least, the follicle with its contained secreting cells was originally a single closed cell, of which the secreting cells are the progeny. This is the case with the Peyerian glands, which are best known to us in this condition, but which afterwards open and discharge their contents into the intestinal canal. Dr. Allen Thomson has ascer- tained that the primitive condition of the gas- tric gland also is that of a closed vesicle ; and Henle has extended this view to the terminal follicles of the more complex secreting glands, which he considers to have originated in the same condition. The observations of Prof. Goodsir upon the testis of Squalus coniiibicus show that this is the true account of the changes occurring in that organ ; the follow- ing stages being distinguishable in its structure, when it is in a condition of activity : — 1st, Isolated nucleated cells attached to the side of the duct, and protruding as it were from its outer membrane (/g. 321 . «). 2nd, A cell containing a few young cells grouped in a mass within it, the parent cell presenting itself more prominently on the side of the duct. 3d, A cell attached by a pedicle to the duct, the pedicle being tubular, and communicating with the duct ; the cell itself being pyriform, but closed and full of nucleated cells (6). * Anatomical aud Pathological Observations, p. 39. G G 3 45t SECRETION. 4th, Cells larger than the last, assuming more of a globular form, still closed, full of nu- Fig. 321. Progressive development of vesicles of testis of Squalus cornubicus. a, portion of duct with a few nucleated cells, the primary or germinal cells of the future acini, at- tached to its walls ; h, c, d, e, f primary cells, or acini, in successive stages ; g, one of the secondary cells in an immature state ; h, a secondary cell elongated into a cylinder, each cell of its com- posite nucleus elongated into a spiral ; i, k, the spiral cells or spermatozoa free. {After Goodsir.) cleated cells, and situated mire towards the surface of the lobe (c). 5th, The full sized vesicles situated at the surface of the lobe, with their contents in various stages of deve- lopment (d, e, f). These vesicles are spheri- cal and perfectly closed ; that part of the wall of each, which is attached to the hollow pedicle, forming a diaphragm across the pas- sage, so that the vesicle has no communica- tion with the ducts of the gland. The con- tained cells are at first spherical (g) ; but as the spermatozoa are gradually formed within them, they present a cylindrical form (A), and they are arranged within the vesicles in somewhat of a spiral manner (/). When the development has advanced to this stage, the diaphragms across the necks of the vesicles dissolve away or burst ; and the bundles of spermatozoa float along the ducts of the gland, some of them separating into indivi- dual filaments (i, k). Besides the bodies now described. Prof. Goodsir has observed what he considers to be vesicles which have discharged their contents, and which are in a state of atrophy (^fg. 322. a). The testis of Squnlus cornubicus, the func- tional history of which has been now given, is considered by Prof. Goodsir as a type of a number of glands, whose action takes place after the same manner; and he lays down the following general facts, which he has ascer- tained in regard to glands of this order. " 1st, The glandular parenchyma is in a constant state of change, passing through stages of development, maturity, and atrophy. " 2d. The state of change is contempo- raneous with, and proportional to, the forma- tion of the secretion, being rapid when the latter is profuse, and vice versa. " 3d. The acinus is at first a single nu- cleated cell. From the nucleus of this cell others are produced. The parent-cell, how- ever, does not dissolve away, but remains as a covering to the whole mass, and is ap- pended to the extremity of the duct. Its cavity, therefore, as a consequence of its mode of development, has no communication with the duct. The original parent-cell begins to dissolve away, or to burst into the duct, at a period when its contents have attained their full maturity. This period varies in different glands, according to a law or laws peculiar to each of them. " 4. The secretion of a gland is not the product of the parent-cell of the acinus, but of its included mass of cells."* An ideal representation of these successive changes is given in fig. 322. At b is seen a Fig. 322. Ideal representation of changes occurring in vesicular glands. a, a bunch of acini in various states of development, maturity, and atrophy ; b, c, d, are diagrams, ar- ranged so as to illustrate the intimate nature of the changes which occur in vesicular glands when in a state of functional activity. (After Goodsir.) portion of gland with two acini ; one of them being a simple primary cell, the other being in a state of development, its nucleus pro- ducing young cells. At c, both acini are ad- vancing ; the second has almost reached ma- turity. At d the second acinus is ready to pour out its contents, and the first to take its place ; and at e, the second acinus is thrown in a state of atrophy, whilst the first is be- come fully matured. There is another set of glands, in which the follicles remain persistent for a much longer period, and continue to produce many suc- cessive generations of secreting cells ; of these, the liver of the Crustacea may be taken as the type. From the appearances presented by these follicles, which have been already figured and detailed (fig. 312.), it seems fair to conclude, that the develoi)ment of these cells * Anatomical and Pathological Observations, p. 30. SECRETION. 455 takes place from the caecal extremities ; and Prof. Goodsir considers that they originate in a " germuial spot," which is the persistent nucleus of the parent cell, whose enlargement and connection with the gland forms the folUcle. Growth in glands of this kind is regulated, according to him, by the following laws : — " 1st. Each follicle is virtually permanent, but actually in a constant state of develop- ment and growth. " 2d. This growth is contemporaneous with the function of the gland ; that function being merely a part of the growth, and a conse- quence of the cu'cumstances under which it occurs. " 3d. The vital action of some folUcles is continuous, the germinal spot in each never ceasing to develope nucleated cells, which take on the action of, and become, primar\' secreting cells, as they advance along the folUcle. The action of other follicles is periodical. 4th. The wall, or germinal membrane, of the follicle is also (probably) in a state of progressive growth, acquiring additions to its length at the blind extremity, and becoming absorbed at its attached extremity. A pro- gressive growth of this kind would account for the steady advance of its attached con- tents, and would also place the wall of the follicle in the same category with the primary vesicle, germinal membrane, or wall of the acinus, in the vesicular glands. " 5th. The primary secreting cells of the follicle are not always isolated. They are sometimes arranged in groups ; and when they are so, each group is enclosed within its parent-cell, the group of cells advancing in de- velopment according to its position in the follicle, but never exceeding a particular size in each follicle." * Prof. Goodsir further expresses the opi- nion, that there is an order of glands with very much elongated ducts, which do not possess " germinal spots " in particular situ- ations, but in which these spots are diffused more uniformly over the whole internal sur- face of the tubes. To this order he refers the kidney in Man and the higher Vertebrata. We have thought it right to give Prof. Goodsir's statements in full, as being in the main unquestionably correct ; but we must express our own doubts as to that part of the doctrine which relates to the production of the secreting cells from distinct " germinal centres." We have examined a great number of membranes bearing an epithelial covering, without being able to discern these ; and our own impression is, that the membrane itself is in a continual state of change, deriving from the blood-vessel, on the one side, the elements of the new growth, and yielding these up on the other. Of the first devclo]mie7it of secreting struc- tures, a partial account was formerly given (see Gland) ; and as this is on the whole in * Op. cit. p. 31. conformity with our present views, it is only requisite to add here the principal facts, as- certained by microscopic research since thzt article was written. The "plastic mass" of which the entire gland consists in its early condition, is now known to be composed of nucleated cells, which appear to be the parent-cells within which the true secreting cells are afterwards to be formed ; these parent-cells themselves becoming the vesicles or follicles of the gland, by the establishment of communications be- tween their cavities and the branches of the duct. It seems probable that some of the original component cells of the gland coalesce or break down altogether, so as to form the smaller ducts, the development of which has been observed to be quite independent of the protrusion of the principal duct, and of its primary branches, from the cavity of which it is a diverticulum. These last are properly intercellular passages ; which, as Prof. Good- sir justly observes, " is an important consider- ation, inasmuch as it ranges them in the same category with the intercellular passages and secreting receptacles of vegetables." Sources of the demand for the secreting function. — We must now consider in more detail, the causes which render the perform- ance of this function essential to the active existence of every living being. 1, In the first place, nearly all the solids and fluids of the animal body are liable to continual decomposition and decay, in virtue of their peculiar chemical composition. That the living state antagonises this decay, and that decomposition can only take place after death, is a doctrine which long held undis- puted sway in physiological science, but which is now generally admitted to be com- pletely untenable. The resistance to decay which living organised structures present, is rather apparent than real ; for it only con- tinues so long as the circulating current con- tinues to pass through or near them, carrying off the products of incipient decomposition, and replacing these by matter that is newly organised. 2. In the second place, a continual decom- position and decay of an organised fabric is involved in its mere t^e^c/aZ/ye existence. For every portion of it has an individual and indej^endent life, and a limited duration of its own : each part, like the simple isolated cell of the lowest Cryptogamia, grows from a germ, arrives at maturity, and finally dies and decays ; its debris being directly cast off, if the organ be external ; but being taken again into the current of the circulation, to be eliminated by another channel, if the part have no direct communication with the surface of the body.* Perhaps the most obvious example of this general fact is presented to us in the vegetable * The author believes that he may claim the credit of having been the first to enunciate this doctrine in definite terms, and as more than a mere h}T)Othesis. (See Mr. Paget's Lecturer on Nutrition, &c. Medical Gazette, 1847.) G G 4 456 SECRETION. economy. The cells of the woody stem have a long and almost indefinite duration, espe- cially after they have become consolidated by the fiUing-up of their cavities with resinous or sclerogenous secretions ; but those of the leaves, which are much more actively con- cerned in the vital operations, have a short and limited term of existence. The " fall of the leaf" is not the cause of the death and decay of the organ, but its result; for the de- composition of its tissues is already far ad- vanced, when its detachment occurs : — its functions have been fulfilled ; its term of life is expired ; and it is cast off, to be replaced by a new development of cellular parenchyma, which in its turn will discharge the same im- portant function, that of preparing the ma- terials for the growth of the more permanent parts of the fabric. This kind of passive change is more constantly going on in the animal body than is usually supposed, espe- cially during the period of its growth and in- crease. A goad illustration is afforded by the deciduous or milk teeth. " We trace each of these developed from its germ, and, in the course of its own development, separating a portion of itself to be the germ of its suc- cessor ; then each, having attained its due perfection, retains for a time its perfect state, and still lives though it does not grow. But at length, coincidently, not consequently, as the new tooth comes, the deciduous tooth dies ; or rather, its crown dies, and is cast out like a dead hair; while its fang with the bony sheathing, and the vascular and nervous pulp, degenerates, and is absorbed. It is here especially to be observed, that the de- generation is accompanied by some spon- taneous decomposition of the fang, for it could not be absorbed unless it was first so changed as to be soluble. And it is degeneration, not death, which precedes its removal; for when a tooth fang really dies, as that of the second tooth does in old age, then it is not absorbed, but is cast out entire, as a dead part. Such, or nearly such, it seems almost certain, is the process of assimilation every- where ; these may be taken as types of what occurs in other parts, for these are parts of complex organic structure and composition ; and the teeth-pulps, which are absorbed as well as the fangs, are very vascular and sensi- tive, and therefore, we may be nearly sure, are subject to only the same laws as prevail in all equally organised parts."* All the epidermic and epithelial structures, including the secre- tory substance of glands, are continually un- dergoing the same change, by the exuviation of the old cells when their term of life is ac- complished, and by the production of new ones; the durability being different according to the particular endowments of the part, but also varying with changes in the supply of blood, which increase or decrease its vital activity. Generally speaking, those parts which live most slowly are those of which the dir ation is the greatest, and in which there ie con- sequently the least frequent change. Of the exuviation of epidermic structures en masse — a process altogether comparable to the fall of the leaf — \s closely related to it, — namely the changes in the state of nutrition in parts whose nerves have been injured, and which are thereby rendered insensible. The close affinity, however, al- ready shown to exist between the functions of Nutrition and Secretion, is sufficient to make it apparent that they must stand upon the same footing in this respect, and that whatever is true as to the relation of either of them to the nervous system, must be true also of the other. Now it is an observation very frequently made, that parts whose nerves have been paralysed are peculiarly disposed to suffer from destructive inflammation, or to undergo a gradual wasting. The latter of these changes is easily accounted for on the general principle dwelt on under the head of Nutrition, that the degree of nourishment which any orgtate) about 3 milligrammes. The vasa deferentia, which we were only enabled to discover alter a very accurate ex:imination, appeared in the shape of a couple of thin and almost solid strings. Henceforwi\rd the testicles and sper- matic ducts begin to grow, although at first but very slowly. Tne increase of the testicles does not however extend itself in all directions. It is limited principally to the longitudinal diameter, thus causing the subsequent kidney form of these parts. Towards the end of the month of January they reach the length of about H Mm., whilst the transverse diameter is not materially changed : weight of both tes- ticles = 4 Mgrs. In the middle of February" the length reached about 2 Mm., the width 1^, the weight 6 Mgrs. By the end of the month the organ enlarges itself to a body of Mm. in length. If Mm. in width, with a weight of S Mgrs. At the commencement of the next month the testicles measured 2^ Mm. in length, 2 Mm. in width. They had a weight of 15 Mgrs.. which increased at the middle of the same month to 4S Mgrs.. the length simul- taneously increasing to 3 ^ Mm., the width to 2^ The subsequent dev elopement of the testicles is much more rapid and extensive. At the commencement of April we found them to be of a considerable size, with a longitudinal diameter of S Mm., a width of almost 7 Mm. The weight, w e are sorry to say, we did not note down. The microscopical analysis now for the first time exhibited to our view spermatozoa in the different stages of de- velopement. The former stages of develope- ment had not been capable of producing such formations. The testicles obtain their p>erfect develope- ment towards the end of this month (April), when they measure 10 Mm. in length, with a width of 8 Mm., and a weight of nearly f Gramme (0.575 Gramme.). The researches which we have now com- municated are of course only of an average value or validity, and cannot be applied to all individual cases. Deviations from them are theretbre by no means rare. Individual spe- cimens exhibit either a very premature or a very late developement. Thus we met "* ith. for instance, as early as the middle of January, specimens, the testicles of which had a length of 2 Mm., a width of 1^, and a weight of 6 Mgrs., such occurring usually only four weeks afterwards. Towards the end of * VoL L p. 35-L art. Avis. the same month the testicles of another indi- vidual measured a length of 2^, a width of 2 Mm. As an opposite instance, we may mention that we found at the end of the month of February, in the testicles of a sparrow, a length of 1^ Mm., a width of 1 Mm. Furm and historu of developement o f the sper- matozoa.— The first thing that strikes the observer, on entering into a microscopical research of the semen of a great number of ani- mals, is the difference of the shape of the sper- matozoa. The specific shape of these elements generally corresponds with the individual Classes, genera, and species, and this so dis- tinctly, that one may often safely venture to infer from it the systematic position and the name of the animals investigated. We will not, however, venture to determine whether this variety of the shape is connected with the rich variety of animal formations, or whether the specific shape of the spermatozoa has a de- termining influence upou the developement of the germ into a certain specific form. Such a conjecture, however, would certainly not be supported by the circumstance that a corresponding shape of the spermatozoa is frequently met with in animals very far re- moved, indeed quite different, from each other. The variety of form in the spermatic elements is the more striking, because the female ge- nerative elements, throughout the animal creation, are distinguished by a uniform de- velopement. Most of the spermatozoa have a slender, linear body, either filiform throughout, or swollen and enlarged at one end, which for convenience we designate the anterior end. This swollen extremity is differently developed, and frequently grown into a peculiar independent part, as, for instance, into a head or body, from which the other thin and longer part is extended as a whip- like tail. Various other forms of the sper- matozoa cannot, however, well be reduced to this type, or at least only by the assump- tion that the filiform body is abridired in its longitudinal axis, to compensate for which it afterwards increases much in width and thickness. Hence the short dense thick corpuscles of a different shape, which are occasionally found in the genuine semen in- stead of the filiform spermatozoa. The size of the spermatozoa, like the size of all the elementary constituents of the animal body, is only very slight. It is only in a few cases that it exceeds the length of a line, a much shorter dimension being however much more general. Let us now trace the different histological formations of the semen, according to form and connexion in the principal groups in the anuual creation. Man. — In man (in which the sperma- tozoa i^Jig. 323.) are composed of head and tail), as indeed generally in the whole division of the Vertebrata. the size * does not often amount to more than » outside • * We always refer in our measxirements to Pari- sian line? ; a 'miUim. = 0.443 of a Paris line. SEMEN. 475 Of this by far the greatest part is occupied by the fihform tail. For the anterior body there hardly remains more than -i-^^to -f^^^^. The body is rather flattened on the sides, so as to represent the shape of an almond. Viewing it from the surface (Jig. 323. a), it looks like an oval disc, the longitudinal dia- meter of which exceeds the greatest width by Fig. 323. A B Spermatozoa of 3Ian. A, vieAved on the surface ; b, viewed edgeways. about one half, and which extends itself to- wards the posterior part into the filiform caudal appendix. The anterior extremity of the body is usually rather pointed, almost like the lower part of a pear or the point of an egg. If the body is situated on its edge {Jig. 323. b), it resembles a short rod, rather pointed towards the anterior part, the transverse dia- meter of which measures about from one half to one third of the greatest transverse diameter of the lateral surface. The tail is cylindrical, thin at the posterior part, and prolonged into a very fine point, which can only be perceived by the application of the highest magnifying power. At its anterior part, on the other hand, the double outline can distinctly be traced. But the thickness even here is always less than the thickness of the body. Mammalia. — The spermatozoa of the Mam- malia have quite a similar form, but frequently a more considerable size. The genus Mus, the smallest mammals, remarkable to state, are distinguished in the latter respect. The length in Mus decumanus amounts to yV'^^ Mus musculus -r}^^^^,'m Hypudacus arvalis, Sciurus, Talpa -V ^ Plecotus auritus, Cercopithecus ruber -gV^' many other cases, — in Canis, Fells, Erinaceus, Lepus, Cervus, &c., the length of the seminal fibres is about the same as in man. But even then the body is gene- rally of a considerable size; as, for instance, in Sciurus, Cervus, and Lepus, where it mea- sures ■J^■o'^^ as also in Talpa. The size of the body in a rat amounts even to Yi-o^^^' The difference, however, is frequently less considerable. In Canis, Rhinolophus, Hy- pudacus, Mus musculus, &c., the body only measures ^s^'^^ eyen still less in the horse and cat. The form of the body varies extremely*; all, however, exhibit parts corresponding to those of the spermatozoa of man. The fun- damental form likewise is always that of a * Vid. R. Wagner's Icon. Physiolog. Table I. Elements of Physiology, p. 13. flattened oval. The spermatozoa of the mon- key tribe are very similar to those of man ; likewise those of the cat, in which the body has a similar inverted oval shape ; as also those of the hedgehog. The body of the spermatozoa in the mole, as also in the horse, is uniformly rounded off at both cxtren)i- ties. In the Khinolophus it presents the same regular form, but at its anterior ex- tremity it seems to be furnished with a short and thin appendix, resembling a point. In other manuualia the posterior extremity of the body, which is in connexion with the tail, is the narrower one, whilst the free an- terior end appears to be rounded off, or even to be more or less flattened. If the an- terior extremity decreases gradually, the body assumes the usual egg form (Cervus, Lepus), whilst it exhibits more the shape of a pear in cases where that extremity is rounded off (Canis, Sciurus). The width of the body, as well as the la- teral flattening off, likewise increases with the enlargement of the longitudinal diameter. Its extreme developement is reached, as it seems, in Sciurus (Jig. 324?.). Here the body is very Fig. 324. Spermatozoa of the Squirrel (^Scivrus vulgaris^. Viewed in different aspects. expanded and thin, like a fine, transparent leaf- The lateral surfaces are hollowed out, like a spoon, or shovel. The margins, or edges, however, do not participate in this. They appear, especially at the anterior end, much thickened. Another very remarkable form is seen in the body of the spermatozoa of the Muridae. It is attached to the anterior end of the caudal ap- pendix, hke the blade of a knife, but in such a manner that the tail, when viewing the body on the surface, is not situated as usual in the central longitudinal axis of the body, but passes over into one of the lateral margins. It might almost give rise to the conjecture that the one lateral half of the body had arrived at its full developement, Avhilst the other had dwindled away and been lost. In fact, the whole appearance of the body seems to justify the assumption of such a non-sym- metrical kind of developement. At the point which usually corresponds to the centre of the body, the lateral part, distinguished by its thickness, is prolonged into the tail. The thickness gradually decreases towards the upper extremity, which is bent in an arched manner, presenting a convexity towards that 476 SEMEN. margin of the body which projects at the posterior part into an obtuse angle. In the rat i^fig. 325. a) the body is very long, but narrow in proportion, and bent like Fig. 325. A. Spermatozoa of the Rat ; B, of the common Mouse. a sabre at the anterior extremity. The body of the spermatozoa of the domestic mouse is shorter, and may be compared to a bent bistoury. The anterior end, how- ever, is likewise drawn out into a short point, which in the field mouse is very slightl}' de- veloped. Thedifferences in the caudal afjpen- dages of the spermatozoa among the mammalia may be reduced to mere differences in length and thickness. In all of them the anterior part attached to the body distinguishes itself from the posterior part by its thickness, but not always to the same extent. Wherever the spermatozoa distinguish themselves by their length, the tail is likewise proportionably thick. Dujardin* occasionally observed in the spermatozoa of men, at the commencement of the tail part, a small irregularly shaped protuberance, wliich KoUiker (who had like- wise observed this in the semen of rabbits^ * Aiinal. des Sciences, 1837, t. vii. p. 291. supposes to be a mere temporary pheno- menon— only a phenomenon of developement — and that it subsequently disappears, whilst its adhesive matter is expended in the pro- longation of the tail. This assumption like- wise appears to us possible, although it is remarkable that such swellings or protuber- ances are so rarely met with, and, therefore, certainlv cannot be considered as constant associates of the developement. We have only observed a few cases of this description, and that principally in the semen of rabbits. The swellings, which in their physical condition, especially in their refracting power, coincide entirely with the anterior body, have gene- rally a globular shape, but exhibit otherwise many differences in size and position. They are found sometimes at the commencement of the tail part, sometimes rather remote from it. It appeared to us as if the respective ap- pendages were formed less by a swelling of the tail fibre, than by a peculiar enclosing matter. It seemed to us. at least in a single spermatozoon, as if the tail could be clearly distinguished in the interior like a peculiar fibre. Further investigations on this subject are still necessary. The spermatozoa of the mammalia generally lie very irregularly and confusedly. At times, how ever, they are grouped together (as we have especially found in the rat, the guinea pig, and rabbit, and as others have likewise observed in men) in very regular fascicles or bundles, which are formed by the bodies of the spermatozoa adhering by their lateral surfaces, as may be often observed with the blood glo- bules.* It is uncertain, however, whether this group-like association of the spermatozoa is dependent, like that of the blood globules, on definite physical processes. The developement of the spermatozoa takes place among the mammalia in the interior of vesicle-shaped globules, which fill up the separate little canals of the testicles in great quantity. KoiUker has traced this mode of developement first of all in the guinea pig (which is very convenient for these in- vestigations); likewise in the domestic mouse ; but has subsequently, after more extensive researches, determined that the mode of de- velopement in all the mammalia is the same. These developing vesicles have pretty uni- formly a size of about but intermixed with them there are frequently found vesicles of a smaller and of a larger diameter (to t^ct"')- Taken from a fresh dead body, and when ex- amined without being treated with water or any other agent, they are as clear as glass, possessing a delicate contour, and perfectly homogeneous contents. The latter, however, coagulates very readily, assuming thereby a granular quahty ; but this we cannot con- sider as its natural condition. Most of these vesicles are free within the Httle seminal canals {fg. 326. a, b, c). They are frequently surrounded by a cellular enclosure, * Tide Wagner, Ic<>Des Physiolog. tab. 1. fg. 2. Elements of Physiolog;N-, p. 10. fg- 4. SEMEN. 477 either singly (/g. 326. d) or in numbers of three four, six, or seven (/g.326. e). A more con- Fig. 326. BCD Developing Vesicles of the Spermatozoa from the Testicles of the Dog. siderable number of them in one common cyst is unusual ; but they may, according to Kol- liker's statement, amount"^to twenty. The size of the cyst naturally depends on the number and state of developement of the vesicles it encloses. Ordinarily it amounts to about On pursuing the genesis of the vesicles of developement, it will be found that they are produced in the interior of cells, according to the law of endogenous formation. The various circumstances which present themselves during the microscopical analysis support the proba- bihty of this opinion. It is certainly often difficult to determine whether an individual vesicle is destined for the production of other cells (tochter-Zellen), or immediately for the formation of a spermatozoon. But we shall see presently that the daughter cells are fur- nished with the same capacities as the free vesicles of developement ; they are like them in every respect, and justify the inference of a perfect identity with them. Wherever, there- fore, we find these free vesicles of developement, they have, in our opinion, likewise been pro- duced in the interior of other cellular forma- tions, and have only become free by the dis- solution of the former. The real process of formation of the spermatozoa in the interior of the vesicles of developement cannot be reached by our observation. The spermatozoon does not possess at its commencement those sharp, distinct contours — that great refracting power, which afterwards so much distinguish it. Like a slight linear shadowit is seen lying in the in- terior {fig. 327. A, b) ; in addition to which it Fig. 327. A ' B C D Spermatozoa of the Dog in the interior of the developing Cell. is covered by the granules, which are so readily deposited from the liquid part of the con- tents. It is only gradually that it assumes a distinct appearance. At first the body only is seen, being recognisable by its specific form. The tail becomes visible subsequently. The entire spermatozoon lies in a curved shape close to the wall of the vesicle, until it has reached its full developement, when it be- comes free by the bursting of the vesicle of developement. Sometimes 327. c,d) indi- vidual vesicles may be seen, from which the tail of a spermatozoon is projecting, whilst the body is still situated in the interior. The vesicle of developement generally retains, however, its original round shape, even when the sper- matozoon has reached its perfect developement, and begins to stretch itself. Angular vesicles of developement, which occur so frequently in other animals, probably never occur here. It is only in rare cases {fig. 327. d) that the vesicle extends itself into a thin tail-like appendix, which then encloses the posterior part of a spermatozoon, and which is evidently only produced by the stretching of the latter. A law, which KoUiker first pronounced as correct, may here be enume- rated, viz. that only one single spermatozoon, and never a greater number, is developed in each vesicle of developement. The formation of the spermatozoa takes place in exactly the same way in the vesicles of developement, even in those cases where the latter have not become free, but remained enveloped by their mother cells. The sper- matozoa, in this case, are not, however, im- mediately set free by the dissolution of the vesicles of developement ; but they ar- rive, first of all, in the cavity of the ex- ternal cyst. The number of the enclosed spermatozoa therefore depends on the num- ber of the enclosed vesicles of develope- ment, a single fibre only being formed in each vesicle. The presence of several sper- matozoa in the interior of a vesicle, therefore, affords us an immediate proof, that the latter histologically possesses the function of a mother cell, and is not itself the vesicle of developement. But likewise in this case the process ter- minates with the dissolution of the cyst that surrounds the spermatozoa, and which pre- vented their becoming free immediately after the dissolution of the vesicle of developement. According to analogy with other animals, it is very probable that the above men- tioned association of groups of the sperma- tozoa into fascicles is caused by the longer per- sistency of the vesicles of developement in the interior of a common mother cell. At all events, such an occurrence is traceable in almost all other cases in which a similar asso- ciation in groups takes place; and it also happens among the mammalia, to judge from the fact, that a delicate cyst-Hke enclosure is often perceived at the circumference of the bundles. AvES. — The spermatozoa of birds possess uniformly, instead of the short oval and flat- tened body which distinguishes them in mammalia, a body of a long and slender 478 SEMEN. shape, which gradually passes off into the pos- terior tail-hke portion. The body, in most birds prolonged into a cylinder, is distin- Fig. 328. Spermatozoa of the Cock (Gallus domesticus). guished by a greater thickness from the thin and filiform tail, which is twice its length [fg. 328.). In other instances, how- Fig. 329. ever, it makes a number of spiral twists, generally four, which make it look hke a corkscrew. The anterior end, in that case, is generally point- ed, and the posterior end is gra- dually extended into a long and straight tail {fg. 329.). The latter form is generally peculiar to the singing birds, and, indeed, an ex- clusive characteristic of them, en- abling us, even by this circum- stance, to detect the Picarii of Nitzsch from the true birds of song. Birds of the genera Coracias, Ca- primulgus, Alcedo, at all events, show this corkscrew form as little as those of the genera Cuculus, Picus, &c. ; whilst the birds of the raven tribe exhibit this same characteristic in common with the siniiing birds. The number of separate twist- ings or turnings of the body, and their distance from each other, is different, however, in the several families and genera of singing birds. Among the thruslies, for instance, the spiral is very extended, and almost undulating, whilst the numerous twinings pass into one another at an obtuse angle. The twistings are less in number (from 4 to o), in the Lanius (the Shrike) ; they are very narrow, and almost acute- ly angular, whilst they are at a greater distance from each other, among the Finches, where their number is still less (3 to 4). The upper windings are, in most cases, the most considerable, and likewise the most constant, whilst the lower become continually slighter, extend- ing themselves sometimes (especi- ally in Turdus, and likewise occa- sionally in Fringilla) throughout Sperma- the greatest part of the tail ex- tozoonof tremitv of the spermatozoon. The f7l£ length and thickness of the tail, •-f"" • Yike the number and arrangement of the windings, is subject to many changes and fluctuations among the several genera. It is particularly strong and rigid among the Fringillidas, the spermatozoa of which (as in Fringilla ccelebs, the Chaffinch) attain some- times a length of whilst in other cases they are much shorter (in Fr. Spinus = -^o"\ F. Canaria yV'") F- domestica oV'O- The tail part of the spermatozoa of the Lanidse is, on the other hand, very short and fine, its length scarcely measures J^'" — ^o"\ of which about — too' 'go^^ to the anterior spiral body. The spermatozoa of Oriolus are only slightly larger. Among the Thrushes the length is about oV''> of which the anterior spiral body occupies quite one third. The same is the case among most other singing birds, as Sturnus, Hirundo, Parus, Alauda, Arthus, Certhia, &:c. Motacilla and Emberza have spermatozoa of ^V'"* Sylvia (Phoenicurus vibilatrix) and Saxicola of tV''- Among the last-mentioned genera, the spermatozoa form by their shape a kind of approach to the cor- responding formations of the Fringilla, whilst the spermatozoa of others remind us more of these formations in the thrushes and the Lanidse. In other words, the formations just aliuded to form a medium between the latter mentioned birds and the Fringilla. The spermatozoa with a simple cylin- drical body are much more uniform in size and shape, and differ from each other chiefly as regards the length of the tail, very little as to the length of the body. The body generally measures from yl-o'" — -n\s"' (Picus, Falco, Columba, Galius, Pavo, Anas, &c.), but seldom less (in Vanellus and Cuculus = 2^'")- The tail is .very thin, and can usually only be traced to its ter- mination with difficulty. The anterior part, which is connected with the body, is but little distinguished from the posterior, and is always without any remarkable thickening. Its length is always more considerable than the length of the body, the entire fibre gene- rally measuring and rarely less (Va- nellus, Cuculus ) or more (Gallus, Co- lumba). It is an interesting fact that the difference of form of the spermatozoa in birds is associated with a difference in the man- ner in which they adhere to each other. Those which have a simple cylindrical body, are constantly dispersed about in the canals of the testicles without any order, whilst the spermatozoa of the singing birds are generally met with in regular bundles. The spermatozoa in each of these bundles, as in the mammalia, lie together in parallel hnes, and with their tails all in the same direction. It is only in their passage through the vas deferens that the bundles gradually lose their regular connexion. The genesis of the spermatozoa of birds, is essentially the same as among the mam- malia. Their proportions are, however, much more distinct, and therefore more easv to trace. The examination of the domestic fowl is much to be recommended in this re^^pect ; some time ago we described SEMEN. 479 the developement of the spermatozoa of this bird.* The vesicles of developement, in this instance, have a size of 2oo^^^~ lio'^^' They are as clear as glass when in a fresh state, and the spermatozoon in the interior can very readily be observed. At the commencement they are globular. Subsequently the shape becomes more irregular ; sometimes it assumes that of a pear, until finally the enclosure bursts (which generally takes place at the sharp extremity), when the spermatozoon makes if s exit with the tail end first {Jig- 330.). Fig. 330. Spermatozoa of the Cock parti?/ enclosed hy the Cell of Developement. For some time afterwards, the remainder of the vesicle of developement may be seen adhering to the separate spermatozoa. All the cells of developement, however, are not free. We often find large cystiform globules, enclosing a number of three, four, eight, twelve, or sixteen cells of developement, much more frequently than among the mam- maha; these generally have a diameter of T*o'' — iV'— sV'''- But the persistency of these mother cells does not hinder the de- velopement of the spermatozoa in any way. The enclosed cells of developement are equally as capable of producing these forma- tions as the free ones, as one may readily convince oneself by observation through the microscope {fg. 33].). On the destruction Fig. 331. A Mother Cell from the Coch, with three Spermatozoa still enclosed in their Cells of Developement. of the membrane of the cells of develope- ment, the spermatozoa get into the in- terior of the cysts (fig. 332.), where they lie together often in a great number, but never * Lehrbuch der Physiol. 3d edit. § 18. S. 27. in regular fascicular groups. Finally, this cyst also gets dissolved, without, however, Fig. 332. A 3Iother Cell from the Cock, with Spermatozoa free in its interior. having changed its shape in any remarkable way previously. The spermatozoa common to each cyst, however, remain together for a time, being connected by means of the tough albuminous contents of the mother cell. Thus, at least, we feel inclined to explain the occurrence of irregular groups of sperma- tozoa, which, kept together by one common cement, not unfrequently occur in the semen of the cock. According to our observation, the develope- ment of the spermatozoa of the woodpecker and of the pigeon takes place in precisely the same manner; and this may be said likewise of singing birds.* The cells of developement of the latter are however still more rarely to be met with free, and are perhaps always en- closed by mother cells. The number of the enclosed cells is generally very considerable (/g.333.). Fig. 333. Ci/st of the House Sparrow, with enclosed Cells of of Developement. The formation of the spermatozoa in the interior of the individual vesicles of develope- ment is Hkewise very difficult to be traced, principally because the contents of the latter coagulate very readily, thus covering the spermatozoa, and rendering them indistinct. We have, however, succeeded several times in observing the spermatozoa in the house sparrow in the interior of their cells of form- ation (^g. 334.). It certainly requires some practice to discover the windings of the body between the granules of the contents, the * Vide R. "Wagner's figures in Miiller's Ar- chiv. 1836, S. 225., in Fragm. ziir Physiol, der Zeiigung ; in Lehrbuch der Physiolog. § 17. S. 25. ; as also in the Icon. Phys. tab. I. fg. 5. (copied in the article, Entozoa," Vol. 11. p. 112.), wl;;ch however, in consequence of our recent researches, require some correction. 480 SEMEN. more so as the characteristic spiral twistings have not yet assumed that distinctness and Fig. 334. Cells of Developement with Spermatozoa of the House Sparrow. regularity, which they subsequently attain. The presence of the spermatozoa can only be proved with certainty, when they have become tree, after the dissolution of their formative cells, the mother cyst still continuing to en- circle them. Thus we may also explain the former conjecture of one of us, R. Wagner, who thought that the spermatozoa of the singing birds had their origin immediately in the interior of the large cysts. The spermatozoa of the singing birds do not however lie together irregularly in the inte- rior of these c} sts, as in the cock, the pigeon, &c.,but are associated in very definite fascicles, as already described. We are ignorant as to the cause of this arrangement. The number and grouping of the cells of developement in the interior of the cysts do not present any remarkable differences from those in the cock, &c., although the spermatozoa of the latter are constantly devoid of such a regular arrangement. The spermatozoa of the sing- ing birds likewise remain enclosed for some time by the membrane of the mother cysts. At the commencement they lie with re- verted tails close to the interior wall of the cysts, which then assumes an oval form {fig. 335.). Subsequently the tail ends of Mother Cell with a Bundle of Spermatozoa from Fr 'mgilla domestica. the spermatozoa remove themselves further and further from the anterior bodies. The cyst bursts where the points of the tails are situated, and the bundles, which are still covered at the anterior end by the remains of the cyst, as if by a cap, then assume the shape of a retort, or of a knee- shaped bent cylinder. Even in cases in which the spermatozoa have perfectly separated them- selves (fig. 336.), this remainder of the for- mer cyst can generally be traced. We may also see very distinctly a tough albuminous substance between the individual sper- matozoa, from which the tail ends project freely. These proportions experience a small mo- dification in those singing birds, in which the Fig. 336. A Bundle of Spermatozoa from FringUIa ccelebs. tails of the spermatozoa are shorter than among the Lanidae. The cysts here retain almost entirely their original form, or do not enlarge to any extent (fig. 337.). The Fig. 337. Bundle of Spermatozoa in the interior of a Cyst of Lanius. spermatozoa in this case lie quite straight in the cyst from the commencement, and sub- sequently pierce the posterior end of it with their tails. Reptilia. — The spermatozoa of the rep- tilia possess the same shape as those of birds ; that is to say, an oblong cylindrical body, and a very fine hair-like tail. No great differences present themselves in the form of these elements among the rep- SEMEN. 481 tilia with scales. Lizards, snakes, and tor- toises uniformly possess, like most birds, a simple and straight body {Jig. 338.), which, however, is occasionally rather pointed towards the anterior part. This occurs, for instance, in the snakes. The only difference consists in the difference of breadth of body and tail. In the snakes (Coluber), in which the Fig, .338. Fig. 339. formation, which is assumed to be seated on the body lenj^thwise, and which is said to be bent in a zig-zig manner to the right and left. It is true that this fibre is frequently only seen to rise on one side of the sperma- tozoon, and in a shape which would encounige the conjecture just now alluded to (^^g. 340.); Fig. 340. Part of Spermatozoon of Triton. a, body of the spermatozoon ; h, spiral windings of the delicate tail. Spermatozoa of Lacerta Spermatozoon of Rana agilis. temporaria. spermatozoa measure about the length of the body amounts to only ; in the lizards (Lacerta), on the other hand, in which the spermatozoa are smaller {-io'" — -so'"') about ^^o"'- The differences of the form of the sperma- tozoa are however much greater in the group of the Batrachia, which Hkewise distinguish them- selves in other respects by various deviating circumstances. A staff'-hke body with a very thin and proportionately short tail charac- terise the spermatozoa of Rana and Bufo (Jig. 339.). The length of the spermatozoa here amounts to about J^^''^ — ^o'^^, of which the body occupies more than the anterior third. Among the Salamanders the body is likewise cylindrical, but much longer i^J'^), bent in the shape of a sabre, and thickest at its pos- terior end.* Towards the anterior part it becomes gradually thinner, and (in Salamandra at least) furnished at the point with a very small globular knob. The tail is likewise of a considerable length. In the anterior part, which passes into the body, it possesses a not inconsiderable thickness. Towards the posterior part it becomes finer and thinner, until at last it can only be traced with diffi- culty. The end of the tail is, however, not straight, nor curved like the anterior part, but turned up in a remarkable manner, and wound in very numerous narrow spirals round the commencing part of the tail, and even round the body. At least so we may ex- plain the peculiar structure of the spermatozoa of Salamandra, and in this we agree with V. Siebold.f Others, especially French na- turalists, as, for instance, Pouchet, merely suppose the slender fibre, which is so twisted round, to be the contour of a ridge-hke * Vide copies in R. Wagner ; Fragment. Tab. II. t Froriep's Neueu Xotizen, vol. ii. S. 281. No. xl. VOL. IV. but in other cases thetwistings are so distinct that they are not to be denied. We are of opinion that, whenever the tail has been lying only on one side of the spermatozoon, a partial twisting off" has taken place. This notched appearance may be attributed to the tail fibre retaining its spiral tvvistings. It is, however, remarkable that the tail never moves further from the trunk of the body, constantly main- taining only a certain distance from it. We do not venture to decide the cause of this, yet we cannot see in it a positive proof of the correct- ness of Pouchefs view. The length of the spermatozoa is very con- siderable. From the anterior point of the body down to the region where the tail bends itself, they measure in the Salamander ^V'^^ Triton even The spermatozoa of the Proteus seem to possess a still greater length, according to an imperfect statement of Valentin.* Fig. 341. Spermatozoa of Bomhinator igneus. The spermatozoa in Bomhinator igneus (Jig. 341.) are of a structure quite similar to those of the Salamander, only smaller. The body of the former is staff'-shaped, tolerably long, and getting thinner towards both ends. The point is again rather enlarged, and flat- * Repertorium fur Anat. &c. 1841, S. 356. I I 482 SEMEN. tened. The posterior end is continued into the tail, which latter is tolerably thick, and almost straight at its commencement. It gradually, however, assumes a very thin appearance, becoming a very attenuated hair-like ap- pendix, which exhibits the same spiral wind- ings that occur among the Salamanders. The length of the spermatozoa, as far down as where the tail bends itself, amounts to — "so" • Another very singular form of spermatozoa is met with in Pelobates fuscus. The sperma- tozoa measure . There is no boundary perceptible between the body and tail part, but one half of the spermatozoon distinguishes itself from the other by a considerable thick- ness. Both, however, gradually pass into one another. The thicker part exhibits from its commencement a number (generally eight) of spiral windings, which increase in size towards the anterior free end (/g.342.}. The anterior F'lg- 342. Spermatozoa of Pehhates fuscus. end itself does not however participate in this formation. It is of a more delicate qualit}', paler, and has a constant vibrating motion, which gives to it a varying form. It generally appears to be wound in an undulating manner. A fascicular group of the spermatozoa is only found among the Reptiha in Batra- chians ; Bombinator, however, forming an ex- ception. In the latter, as well as in the scaly Reptilia, the spermatozoa lie confusedly toge- ther. In the latter instances we can readily trace thtir production in the interior of se- parate solitary cells of developement ; as, for instance, in Anguis fiagilis, or Bombinator inneus. The cells of developement of the latter animal (which to the number of two or four are enclosed by a mother cell, when in the earlier stages of developement) mea- sure in a developed state about At first, when the spermatozoon forms itself in the interior of these cells, it lies curled up close to the wall. Subsequently the fibre stretches itself, and changes the cell into an obtuse cylindrical enclosure, which finally bursts in the anterior and posterior part, to enable the spermatozoon to make its exit. The remains of the cell of developement continue for a long time adhering to the body of the spermatozoa, generally in the centre, exhibiting the appear- ance of a comb-hke appendix of a variable shape and size. The formation of the spermatozoa in the interior of independent cells of developement likewise takes place in a similar manner in the Lacerta crocea. We have but rarely seen that the same cells are enveloped by larger cysts at the period of the production of the spermatozoa, which is commonly the case in former stages of the developement. The num- ber of cells contained in one common cyst is generally only very small, seldom exceeding eight. The same is found, according to the Fig. 343. Cells of developement of Testudo grceca with Sperma- tozoa and external ci/sts. C After KdlUker.) observations of Kolliker, in Testudo grseca ; but the external cyst in this instance is said generally to persist for a longer period. Tiie persistency of this enclosure is very general among the Batrachians, which distinguish themselves by the spermatozoa being asso- ciated in fasciculate groups. The number of the enclosed cells of developement here is generally a larger one (from ten to twenty). The developement of the spermatozoa in other respects does not, however, exhibit anything peculiar. They are formed as usual, separately in the enclosed cells of de- velopement (/g. 344.). It is only afterwards, Fig. 344. Developing cell of the Frog, with a Spermatozoon in its interior. (After Kolliker.^ when these cells have been dissolved, that the spermatozoa get into the interior of the mother cyst, in which they congregate in fasciculate groups. By their so doing the cyst loses its original round shape, and as- sumes the form of a pear, until it bursts at the pointed extremity, and the tail-ends of the spermatozoa immediately project. The re- mains of the cyst continue recognisable for some time at the anterior end of each bundle. This is the case in the frog at any rate. In Pelobates, on the other hand, the filiform tails of the spermatozoa do not project from that part of the cylindrical enclosure which is burst, but the anterior vibrating bodv does so (/g. 345.). The external cyst of the bundles of sperma- tozoa of the Salamander constantly retain its original globular shape, as the sperma- SEMEN. 483 tozoa do not stretch but remain wrapped up. The spermatozoa of Scymnus niceaensis(./^. It is a remarkable sight to see the cyst burst- 349. a) are similar but rather longer, whilst Fig. 349. A bundle of Spermatozoa of Pelohates. ing on being treated with water. The whole mass of spermatozoa suddenly bursts forth, and only remain attached to each other by the heads, as if imbedded in one common sub- stance. The separate fibres radiate in all direc- tions, each being wrapped up in a spiral form. Fishes. — In the class of fishes, the sper- matozoa occur in two forms. The first is found throughout the osseous fishes, and also in Amphioxus. The other form is found among the Plagiostomes. In the former case the spermatozoa consist (Jig- 346.) of a very small globular body (of 5^0'" — sAo^'^ or even smaller, down to toVo'^^ in Perca fluviatilis), and an extraordinarily thin, hair- Fig. 346. Fig. 347. Spermatozoa o f Perca fluviatilis. Spermatozoa of Cobitis fossilis. like tail, which, however, possesses compa- ratively a very considerable length. Sometimes the body at the point of insertion of the tail has a small knotty appendix, as in Cobitis (^g. 347.), which gives to it a pear-like shape. The body in some genera is so small that it can hardly be perceived with any distinctness. This also applies to the spermatozoa of Fi(T 348 Petromyzon, in which the form of 'the body is, however, different. In P. marinus* the body is egg-shaped; in P. fluviatilis (fig. 348.) staff- shaped. The length of the body in P. fluviatilis is yio'''. The spermatozoa among the Pla- giostome fishes are similarly formed Spermato- to those of the birds. They are long, zoon of filiform, and furnished with an an- zonAuvia- cylindrical body. In Scyllium tiUs.^"^' Canicuia the body is stiff* and quite straight, and tapers at both ends. The tail is thin, and of an equal length to the body (^V'O. * J. Muller, Untersuch. uber zu Eingewerde der Fische, Berl. 1845, S. 6. A. Spermatozoa of Scymnus nicecensis. . Spermatozoon of Toipedo Narce. the body, instead of being straight, describes two long spiral windings. Four more narrow spiral windings are found round the body of the spermatozoa in Spinera acanthias, which measures gV^^ whilst the length of the whole spermatozoon amounts to A similar num- ber of spiral twistings are likewise seen in the body of the spermatozoa of most of the rays, in Torpedo narce {fig. 3+9. b), Raja rubus, &c. In Raja oxyrhynchus it is only the anterior part of the body which is s[)irally wound in a length of about gV'^ whilst the posterior part is straight. The number of the windings is nevertheless, however, more considerable, viz. 7 or 8. The length of the whole s[)ermatozoon amounts to y-''''. Chimera monstrosa like- wise exhibits these windings, notwithstanding the comparatively short body (y^o'^O of its spermatozoa, which have a length of 2V The number of windinns is three. The developement of the spermatozoa in fishes has as yet only been observed in the Plagiostomes. It is exactly the same as in frogs and birds, as the statements of Hallmanu* lead us to infer. Almost all of the sperma- tozoa are united with one another in bundles. According to our researches in Torpedo Narce, the spermatozoa are produced sepa- Fig. 350. Ci/sts, with developing cells from the testicle of Torpedo Narce. rately in the cells of developement, which pos- sess about the size of ^ and which are * Mllller's Archiv., 1810, S. 467. 1 I 2 484 SEMEN. Fi2. 353. enclosed by a lesser or greater number of but here, as well as in the Lacerta, &c., the cyst-like mother cells {Jig. 350.). The size of formation of the spermatozoa only takes place each of these cysts amounts to about wherever the number of the enclosed cells is small ; but in the reverse case it may in- crease to -io"^. The cells of developement dissolve after the formation of the sperma- tozoa, and the latter then get into the in- terior of the cyst {Jig. 351.). The spiral wind- Fig. 351. Spermatozoa in the interior of the cysts {Torpedo Narce'). ings of the body seem to be still wanting at this stage, or, at least, not to be perfectly developed. If the number of spermatozoa is only small in one cyst, they never group together into a bundle, whilst this is con- stantly occurring in the reverse case {Jig- 352.). Fig. 352. Bundle of Spermatozoa in a cyst { Torpedo Narce). We will not venture to decide, however, whe- ther this difference is entirely attributable to the greater number of the cells of develope- ment ; and we are the less inclined to do so, as we have already seen, when investigating the spermatozoa of birds, that, even with an equal number of the formations alluded to, the grouping of the spermatozoa in the in- terior of the cyst may be different. This much, however, is certain, that the num- ber of the enclosed cells is not entirely with- out influence. The fact of the fascicles of spermatozoa always coinciding in one cyst with a greater number of the cells of develope- ment, seems, at all events, to favour this con- jecture. Previous to the period of procreation, we also find, in the testicles of the osseous fishes, that the cells of developement are enclosed in the interior of larger cells {Jig. 1^53.) ; Spermatic cells from Cyprinus hrama. subsequently to the destruction of the cyst, and to the consequent independence of the cells of developement. We infer this from the circumstance that we have never seen in them any real bundles of spermatozoa. The state- ment of Kolliker that the spermatozoa of Am- phioxus develope themselves from little cells (of ToW — tW). ^vhich lie together in groups of from six to twenty-five, also seems to support the correctness of our conjecture. Each of such groups appears to us to be the brood of a single mother cell. The mother cells themselves, however, are of such a small size, that the formation of such brood in their inte- rior is not to be traced or perceived. It can only be seen that these cells gradually lose their round shape, and that they assume a pear, or spinclle-like form. This, unquestionably, is merely the consequence of the endogenous developement of a spermatozoon, which gra- dually stretches itself, thereby causing (as in Gallus, Rana, &c.) the change of shape of the external enclosure. Thus much of the proportions of form, and of the mode of developement of the sperma- tozoa among the Vertebrata. We have treated this subject somewhat elaborately, partly be- cause the spermatozoa of these animals are those which may be most frequently obtained for observation, — partly also because it is in them that the stages of developement can be better traced and recognised. We have invariably met with in them a common type, not merely in the external shape, but also in the mode of developement of the spermatozoa ; and these are circumstances which will be of importance to us in interpreting the stages of developement of the spermatozoa in the lower animals, in which they are as yet enveloped in great ob- scurity. MoLLUscA. — Among the Invertebrata, the division of the Mollusca uniformly possesses (as in the Vertebrata) filiform spermatozoa, which are enlarged at the anterior extremity. This anterior extremity does not, however, every where form a particular division, as a body, distinct from the posterior thinner part or tail. On the contrary, the one passes in many cases so gradually into the other, that it is im- possible to determine the boundary between the two. The tail then appears to be a mere pointed continuation of the anterior enlarged part. The two thus distinct forms of sper- matozoa are, however, again united with one another in various ways. SEMEN. 485 Cephalopoda. the Ce- phalopods we meet with the former form of spermatozoa with a distinct body and a thin and long hair-like tail, as among the scaly reptilia, &c. The body is cylindrical, or staff-shaped, in the spermato- zoa of Octopus vulgaris {fi^. 354.), which have a length ofy^ of which ri/^' belongs to the anterior body. The spermatozoa in Sepiola are shorter, and furnished with a body which measures aso • The developement of these spermatozoa occurs just as in birds, according to Kolliker. The separate spermatozoa may be perceived very dis- tinctly in the interior of their cells of developement. The fascicular grouping is want- ing, although the spermatozoa remain enclosed for some time by the mother cells. These fibres in the Cepha- lopods are, however, sur- rounded in their passage through the vas deferens by peculiar sack-like enclosures or Sperma- tophores, which are formed from the secre- tions of the gland contained within the walls of that channel. These enclosures gra- dually assume a very strange complicated structure, which we have only become ac- quainted with, within a recent period, through the excellent researches of Milne Edwards.^ They assume the shape of cylindrical bags of a not inconsiderable size, so that they may readily be perceived with the naked eye. They contain at the posterior extremity a peculiar apparatus (besides the Spermatozoa, which are accumulated at the anterior thicker end), which is distinguished by a particular me- chanism adapted for the expulsion of the seminal liquor. Gasteropoda. — The spermatozoa of the Gas- teropods exhibit, only in rare cases, as it seems. Fig. 355. M 3 ^ J Spermatozoon of Octopus vulgaris. Spermatozoa : A, of Patella ; b, of Chiton. a similar form to those of the Cephalopods. This is the case, for instance, in Chiton and * Annales cles Sciences Nat. 1842, tome xvii. p. 335. Patella {fig. 355.). The spermatozoa of the former consist of thin delicate fibres of -J^'^^, the anterior body of which has an oblong shape, measuring about -^^q''' . The body in Chi- ton is broader, almost pear-shaped, and of a more considerable size {-^-^o'"). Similar cer- caria-like spermatozoa are possessed by Ha- lyotis and Bermetus, as also by Trocluis and Paludina impura. The strict distinction be- tween body and tail is, however, wanting in most of the other Gasteropods. The sper- matozoa then have a filiform shape, and in- crease gradually in thickness from the pos- terior, pointed, towards the anterior end. The head or cephalic end is flattened. It is thus, for instance, in Carinaria ; also among the Nudibranchiata, Hypobranchiata, Poinato- branchiata, and Ptcropods. At the same time the spermatozoon usually exhibits a num- ber of light spiral windings, which diminish uniformly from the anterior to the posterior end {Jig. 356. a). In Paludina vivipara (which, Fig. 356. Spermatozoa, A, of Doris ; b, of Paludina vivipara. from the form of the spermatozoa, likewise belongs to this description, although the thin- ner tail part is distinguished by a greater length) the spii-al windings are closer, as among the singing birds, and confined to the anterior body only (fg. 356. b). The sperma- tozoa of most of the other species of this genus possess quite a different form. In Turbo, Buccinum, Purpura, they are simply filiform, and equally pointed towards both ends. In Turbo they measure -^q'^' — -^o''\ Thedys, Aplysia ^V'^^ '"^ Pleurobranchia Meckelii even The spermatozoa of pulmonary Gasteropods are usually still larger, extending to V'\ as in Helix. As in the Nudibranchiata, they likewise become gradually enlarged towards the anterior part, but not flattened at the cephalic end, being, on the contrary, fur- nished with a short point (in Helix of ^io'^O* with an appendix, which must be viewed as a peculiar form of body {fig. 357.). The same is thickest at the posterior part, thicker than the body, and gradually gets thinner to- wards the end. In most cases (Helix, Arion, I I 3 486 SEMEN. windings, almost in the form of an S. Fig. 337. Clausilia, &c.), it exhibits two easy spiral quently in an irregular manner, generally Some measure but are sometimes larger, to the extent of t^'^^ above it. In the interior of these cells we meet again with vesicular formations, generally mea- surin^:: The contents of these vesicles coagulate on being treated with water, &c., into a fine granular mass, exhibiting some- times a simple or double granule of extra- ordinary size. The number of the enclosed vesicles, which evidently were produced in an endogenous way, is usually very small, mostly 1 or 2, more rarely 3, 4, or 6. The developement of the spermatozoa takes place in the interior of these last-men- tioned vesicles (Jig. 359.). According to the Fig. 359. Spermatozoon of Helix pomatia. easy spiral windings are also not unfrequently observed at the enlarged body. The mode of formation of these sperma- tozoa can usually be traced without any great difficulty. It usually takes place in the same way as in the animals already described, as proved hy K'dlfiker^s excellent researches. Even in the Gasteropods we may observe the deve- lopement of the spermatozoa in the interior of particiihir vesicles. The arrangement of these parts only exhibits some deviation. In Helix or Clausilia, in M^hich the stages of this mode of developement can best be ob- served among our native snails, we meet with in the interior of the testicle, besides the de- veloped spermatozoa, numerous larger and smaller aggregations of vesicles (in number varying from ten to forty), which are seated on the external surface of a round or oval globule (^g. 358.), which is in diameter to ,V"- On a nearer research, it will be found that this globule is not a cell, as one might sup- pose at first sight, but merely a mass of a Fig. 358. Group of vesicles from the testicle of Helix pomatia. tough substance, in which a number of small brown granules are embedded, exhibiting a great similarity with the yolk molecules from the eggs of Helix. There is no external en- closure around this globule. The periphe- ral vesicles or cells, which adhere to it fre- Spermatozoon of Helix pomatia in the interior of its developing cell. (After Kdlliker.) observations of Ko/li/cer, the head is produced first, being at first of a less regular, un- wieldy shape. The tail is formed subse- quently, attaching itself in spiral windings to the internal surface of the cell wall. On the s" cmatozoa being sufficiently developed, the vc .icle of developement is dissolved, and the spermatozoa get into the cavity of the exter- nal cell (fig. 360.). Here they may usually Fi2. 3G0. Spermatozoa of Helix pomatia in the ijiterior of their mother cells. be perceived with great distinctness, whilst they can but rarely be distinguished in the in- terior of the real cells of developement. At first the mother cells retain their original round form, even after the reception of the spermatozoa. They soon, however, on the windings of the fibres being stretched, extend themselves k ngthwise, and assume an ellipti- cal or pyriform shape. At a still later period the cell pushes forward (at the point where the heads of the spermatozoa are situated) a long pedicle-formed process, which contains the anterior extremity of the spermatozoa (Jig. 361.). The point of this process or continu- ation constantly remains connected with the central globule of the former mass of vesi- cles, whilst the posterior belly-like part of the cell removes itself further and further from it. The same att - chment takes place after- wards with the heads of the spermatozoa, on their being projected from the anterior end of this process, which usually happens soon. At this period the mass of vesicles reminds us SEMEN. 487 strongly, owing to its shape, of a group of vorticellae {Jig. 362.). i^^g. 361. i^^g. 362. Spermatozoa of Helix po- A group of Spermatozoa matia at their extrusion of Helix pomatia, from the mother cell. partialhj protruded from the mother cell. As soon as the heads of the spermatozoa have projected, the remainder of the mother cell lengthens itself, and becomes a delicate cylindrical envelope. These remains still ad- here to the spermatozoa when completely ex- tended, exhibiting the appearance of a couple of larger or smaller knobs on the tail : the same thing occurs in the spermatozoa of the frog. This mode of developement is not changed by the presence of a greater number of sper- matozoa in the interior of the mother cell. All the difference that may be seen is, that one spermatozoon comes forth rather earlier than another. The free spermatozoa are, however, by no means distributed without order over the surface of the central globule to which they still adhere. On the contrary, they are grouped together into one com- mon fasciculate mass, in the same manner as we have already described in the singing birds. This circumstance is remarkable, be- cause it shows us that the formation of a bundle of spermatozoa is not occasioned every- where by the same means, and therefore does not always justify the inference of the persistence of an enclosing cell. A separation of the bundles of spermatozoa happens in Helix : the central globule (which forms the common cement that holds together the individual spermatozoa, in the same way as the tough albuminous mass in the C3'sts of the singing birds) gradually passes away. The developement of the group of vesi- cles in Helix is very interesting and im- portant. It is at once apparent that the same has originated from the brood of a single, originally simple, cell, and that through a continual endogenous increase. Our re- searches have afforded us the immediate proof of the truth of th^s, confirming, at the same time, the conjecture of KoUiker ; viz. that the primitive spermatic cells are the same formations which have been described as epithelial cells of the follicles of the testicle. In the interior of these cells, the contents of which consist of a brownish granular homo- geneous substance, a certain number of vesi- cles are gradually produced, which continually increase in an endogenous manner, until the bursting of the mother cell, when the daughter cells deposit themselves around the globidar remainder of the cellular contents (^fg. 363.). Formation of groups of vesicles around the epithelial cells of the testicle in Helix pomatia. The developement of the spermatozoa in the other Gasteropods is similar to that describ- ed, although not in all cases so distinct as in Helix. The endogenous formation of the spermatozoa can only with difficulty be per- ceived in Lyma, Lymneeus, &c. ; it would rather appear as if they were produced by immediate growth from vesicular elements. The general rule is, that they are united with each other into groups, in which, how- ever, the interior central globule is some- times wanting (as in Cyclobranchiata, in Turbo, Buccinum, &c.) ; but this does not change in any way the developement and mode of grouping together of the sperniatozoa. We have also, in this instance, in the united vesicles of a group, unquestionably only the brood of a common mother cell, which group may have enlarged after the destruc- tion of the external membrane that sur- rounded it. The only difference would consist, in the circumstance that the entire contents of the mother cell are employed for the structure of the daughter cells, leaving no remainder, which perhaps might induce a more firm connection of the separate ve.-ii- cles in the shape of a round mass. Acephala. — In comparison with the variety in the form of the spermatozoa among the Gasteropods, we meet with bat slight differ- ences ill the class of the Acephala, at least among the Lamellibranchiates.* The sperma- tozoa of these Mollusca consist of delicate fibres of about ^iQ^'Mn length, the anterior end cf v/hich supports a short and distinct body of Fis.SQ^. variable size (from -oW' — ^ 4io"0 (/^-Sei.). This body j| is usually (as in Unio, Cyclas, j Clavagella) cylindrical ; in other cases (for instance in Mytilus, Pholas) pear-shaped. Respecting the formation of these fibres we only know Kol^ hker^s opinion of it, viz. that they are produced in bundles from round cellular masses, and through an apparent prolonga- tion of the vesicles ; as, for in- Spermatozoon ^^^^ . of Unto. . \ r TT • amination or Unio was not calculated to give us an insight into it. * VideV. SieboldinMuUer's Aichiv. 1837, S. 381. 1 I 4 488 SEMEN. Spei'mntozoon of PhaUuria monacha. (^AfterKoUiker. ) Tunicafa. — Among the Tunicata the Ascidia possess spermatozoa quite similar to those of the Lamellibranchi- Fig. 365. ates, having a dis- tinct head of dif- erent shape and a slender tail. The size of the sperma- tozoa is, however, usually rather larger (/g-.365.); the head is usually t^o'^^ — the'tail fluctu- ating between ■^■^"^ The sper- matozoa seem to want a body in the Salpae, according to the observations of KoUiker. The endogenous formation of the spermatozoa in the Ascidia is as little distinct as among the Lamellibranchiata. It seems, also, with regard to the former, that the developing vesicles simply extend themselves into the spermatozoa. At a previous stage of deve- lopement, these vesicles are, however, con- tained (either singly or in a greater number) in the interior of cells. Articulata. — In the second great division of the Invertebrate animals, among the Arthro- j)oda, the filiform shape of the spermatozoa, if indeed it occurs at all, is generally still more marked in its developeuient than in the Mollusca. The spermatozoa are long and slender fibres, which, perhaps in all cases, are deficient of a real, distinct, and separate body, being at the utmost only slightly enlarged at the anterior end. The spermatozoa of some few groups, however, differ from this, and ex- hibit so striking a form and arrangement that one can hardly at first recognise in them the genuine spermatic elements. The question, indeed, arises, whether these parts are really in all cases the developed spermatozoa, or whether they do not constitute mere stages of developement. We shall subsequently return to this question ; let the remark suffice for the present, that in some cases the circumstances observed seem to favour the latter hypothesis. Insecta, — The spermatozoa among the hexa- pod insects are of great uniformit}'. They ap- pear, without exception, as filiform fibres '(^o-. 366.), which are frequently distinguished by being extremely slender in proportion to their length (the latter exceeds f^^in Staphylinus, but is generally less ; in Culex 23"^; in Agrion Virgo -^q'" — aV^O- The anterior end is pro- bably always rather thickened for a consider- able extent, and thereby distinguished from the posterior pointed end of the fibre. Remark- able deviations from this fundamental shape occur but rarely, but are nevertheless not en- tirely wanting. We may mention, for instance, that a peculiar angular appendix is found in the spermatozoa of the Locustinae at the an- terior end of the bod}^ this appendix being formed of two short crura, which converge and pass into one towards the anterior part, like the head of an arrow. Fis. 366. Spermatozoa of an Insect. The spermatozoa of the Hexapods are developed in the same endogenous man- ner, as among the Vertebrata. This process may very easily be observed. The vesicles of developement, which measure pretty uniformly, when in a developed state, ^^q' ' (they are smaller in many Diptera, Culex (3^'^'), Musca, Fis. 367. Ci/sts, ivith developing vesicles, from the testicle oj Staphylinus cyaneiis. &c.), are in a variable, generally, however, in considerable number (twenty, thirty, forty), enveloped by larger cysts {fg. 367.) These cysts or enveloping cells frequently attain the size of J/'' (Carabus, Staphy- linus, Locusta, &c.),'and they are evidently the mother cells of the enclosed vesicles. In the upper division of the testicle, the SEMEN. 489 number and size of the latter is generally much smaller than in the lower part. It fol- lows, of course, that the size of the mother cells themselves is influenced by the size and number of their contents : wherever the number of the enclosed vesicles is small, the cyst never attains a considerable size. In Culex, for instance, it seldom exceeds 1 /// 1 /// Too T 5 • The vesicles surrounded by the cyst are as clear as glass, and, when uninjured, contain an entirely homogeneous material, which, how- ever, appears granulated on being treated with water, and then also it sometimes forms a Fig. 368. Developing cells of the Spermatozoa of Culex. large nucleus-like body in their interior. In each of these vesicles, as V. S'lebold'^ has shown, a single spermatozoon is usually produced {fig. 368.). It attaches itself in numerous windings to the inner surface of the cell wall, until it has reached its full develope- ment. In the mean time the vesicle loses its original round shape, becoming stretched, and assuming the most various forms {fig. 369.). At last the vesicle bursts at some place, and allows the spermatozoa to come forth. ( Fig. 370.) The spermatozoa having thus become free, group themselves together into regular bun- dles, still enclosed by the mother cell of the vesicle of developement. This at least seems to be the case invariably wherever the cyst persists long enough. It, however, some- Fig. 369. /' Spermatozoa in tlie interior of the vesicles of develope- ment of Nepa cinerea. times disappears at an early period, as, for instance, according to Kolliker, in Musca, in * Uber (lie S^jermatozoiden der Locustinen, A. a. 0. S. 1. which case the vesicles of developement form loose groups, as in Amphioxus. Fig. 370. Spermatozoa partially expelled from the^vesicles of developement of Nepa cinerea. , The bundles in many cases disperse as soon as the mother cells are destroyed. But it still more frequently occurs that these bundles survive the existence of the cyst, the remainder of which then covers for some time to come (as in the singing birds, &c.) the anterior end of the bundle in a cap-like form. (Instances — Coleo[)tera, Neu- roptera, &c.) In this part, which is ge- nerally lengthened, the separate spermatozoa lie together in a remarkably dense manner, being almost united together into one com- mon mass. It is different, however, in most cases with the posterior division of the bundles {fig. 371. A.), where the separate fibres start away from each other. In this way the usual pear, club, or retort shape of the spermatozoa bundles is produced.* It is but rarely the case that the spermatozoa present, in their whole length, an arrangement similar to that which is usual at the anterior end. The whole bundle of spermatozoa then appears as {fig. 371. b) a homogeneous structure, and might Fig. .371. Bundles of Spermatozoa, A, from the testicle of Sta- phylinus erythropterus ; B, of St. cyajieus. {After Siebold.^ readily be taken for a single colossal sperma- tozoon, if the observation of the develope- ment had not taught us otherwise. Of this, however, we may convince ourselves by ma- * We are inclined to regard as bundles of sper- matozoa of this kind, those formations from the testicle of Paludina vivipara, which V. Siehold de- scribed as a second form of spermatozoa. MUller's Archiv. 1836, S. 246. 490 SEMEN. nipulation, pressure, &c., whereby the sepa- rate constituent elements can be demon- strated. In Staphylinus cyaneus {Jig. 371. b) these bundles are wraj)ped up into one roundish knot (excepting the anterior ones, which are still covered by the remains of the cysts) ; in Panorpa communis they have curled arrangement. In many cases, several of such fibres join themselves lengthwise into one restiform mass, which is still covered in the interior of the testicles by a common gelatinous enclo- sure. This produces the long vermiform bodies, which are so frequently met with in the testicles of the butterflies, but which also occur in some few other insects, as in Diptera (e. g. in Scatopsis). ^ In their gradual advance through the vas deferens, the spermatozoa lose this mode of grouping; — their bundles separate. In the |)lace of this they are, however, very fre- quently enclosed in masses by peculiar baglike enclosures, the so-called Spermntophora^^ such as we find in the spermatozoa of the Ce- phalopods, only of a much more simple struc- ture. By the aid of these formations, the spermatozoa are transferred into the female generative organs. Formerly it was usual to look upon the remains of these bags as the torn-off generative organ of the male. The spermatophora of insects have usually the form of a pedunculated globule (for instance, in the Locustinae and Lepidoptera). Through a series of transition-forms they reach ulti- mately the shape of a long thin cylinder, of which a striking example is afforded in Clivina Fossor. The spermatozoa lie either irregularly in the interior of the spermato- phora, or united into regular bundles. This mode of grouping has an extremely elegant appearance in the Locustinae. The tails of the fibres join together on either side of a furrow, from which the several fibres start to the right and left like the barbs from the shaft of a feather. Spermatophora are want- ing in many of the Hexapoda. Instead of them we sometimes find (as in Carabaea, Titfigoria, &c.) a number of long and rather broad bandlike transparent strings, which are fre- quently wound in the shape of a spiral, and, like the spermatophora, are also formed in the vas deferens of the male. These strings, on being treated with water, separate into a great number of spermatozoa, the separa- tion taking place either gradually from the ends, or more suddenly in their whole ex- tent. The entire mass thus proves itself to be one large seminal string, a formation which, in its whole quality, approximates very nearly to the second form of the seminal bundles from the interior of the testicles enumerated by us. The cause of such an arrangement and grouping of the spermatozoa is equally as unknown to us as that of the formation of the bundles of spermatozoa in the cysts. Whether they are peculiar phenomena of at- traction, or whether they are other relations caused by external influences and circum- stances, we know not. We must therefore for the present be satisfied with a simple statement of the facts. Although, from the great uniformity of the spermatozoa in the class of Insects, we might reasonably expect a corresponding simi- larity in the other groups of the Arthropoda, observation teaches us that such is not the case. Instead of the filiform formations, which, however, are here the usual constituents of the seminal liquid, there are found in some cases quite peculiar bodies of a re- markable shape. The history of their de- velopement alone can prove that the ele- ments alluded to are not, as one might perhaps suppose, morphologically different formations, but that they owe their origin to a mere modification in the application of the ordinary stages of developement. It can be proved that the bodies in question in most cases are immediately connected with the former stages of developement of the spermatozoa. Thus our conjecture (above expressed) gains in probability, that many of such-like little bodies are mere forms of de- velopement of ordinary filiform spermatozo;i. The following investigations, however, will afford us a confirmation of the truth of our conjecture : — Arachnida. — In the class of the Arachnida, the usual filiform appearance of the sperma- tozoa has only been observed among the scor~ pions. The spermatozoa of these animals are about long, and rather thickened at one end. They develope themselves, according to Kdliikcr, in the usual manner in the interior of vesicles, which are contained, in numbers, in a larger cyst-like cell. In the Arnnc^e, on the other hand, which, owing to the difficulty of an anatomical ex- amination, have hitherto but rarely been submitted to a careful inspection, the sper- matozoa are said to present a very dif- ferent shape. V. Sicbold*, to whom we are indebted for the only statements regarding them, describes them as round or reni- form cellular bodies, on the interior wall of which a round or oblong nucleus is situ- ated. We have also met with such corpuscles, and that in great quantity, in the testicles of the most different species of spiders ; we must however dispute the assumption of V. Siebold, viz. that such are the developed spermatozoa, since we have succeeded in discovering filiform bodies besides these for- mations, which former undoubtedly develope themselves from the latter, and are the real spermatozoa. These relations we have re- ^ cognised most distinctly in Clubiona claus- ' traria. The contents of the testicles here consist of a large number of small round cells oi\^~'^,\n which a very perceptible nu- cleus is contained. The nucleus is at first round (Jig. 372. a), but gradually elongates Vid. Stein. * Lehrbuch der Verglucheiiden Anatomie, § 544. SEMEN. 491 itself, and then becomes a short, and gene- rally curved, cylinder (b), one end of which Fig. 372. BCD Seminal cells in the testicles of Qubiona claustraria. is frequently club-shaped. The nucleus at the same time generally urges itself to- wards the outside, its point penetrating through the external cellular membrane. The projecting part of the nucleus generally ap- pears like a protuberance at the margm of the cell, the greater part of it being still situ- ated in the interior (c, d). In some cases, however, it breaks forth in its whole length (e). It then looks like a peduncle-shaped appendix. We have Fig, 373. Seminal fibres of Cluhiona. not been able to discover further stages of develope- ment in the interior of the testicles ; but we have suc- ceeded in detecting, besides the already mentioned cor- puscles, a number of dis- tinct linear fibres of Jq^'" — (^Jig. 373.) in the spoon- shaped capsules on the pal- pi of the males, which, no doubt, were developed sper- matozoa. The anterior half of these was generally bent in an arched cylindrical form, and thicker than the pos- terior tail -like part. Very similar, only rather longer, seminal fibres are likewise found in the seminal capsules of the palpi in a species of Tetragnathus. It can hardly be doubted that these fibres have originated from the previously described spermatic cells. The changes of form to which the nucleus is subjected in the course of developement present a gradual approximation to this form of spermatozoa, at least to the form of the anterior thick- ened corpuscles, with which the nucleus moreover corresponds in its physical cha- racters. In order to render the metamor- phosis of the nucleus into spermatozoa com- plete, it certainly is necessary that the external cellular wall should disappear; but this is a general rule in the developement of spermatozoa, and probably also takes . place here, although we cannot furnish any * immediate proof of it. It must, however, appear remarkable that we have never met with developed spermatozoa in the testicles them- selves. We could only trace in tliem cells of developement, formations which, besides the spermatozoa, also occur in the capsules of the palpi. The question might be asked whe- ther this would not render the inference justifiable that the spermatozoa only at- tained their final developement at the latter spot, and therefore at a distance from the place of their formation. From our described observations we c&nnot yet venture to decide this question with certainty. The circum- stance is, at all events, very remarkable, and would be the more so in case V. Siebokrs statement that the cellular seminal corpuscles are to be met with even in the receptacula seminis of the female spiders, were to receive confirmation. In our description of the developement of the spermatozoa in Clubiona we have left the question undetermined, whether they ori- ginate directly from a metamorphosis of the nucleus, or through endogenous formation in the interior of it. — We have not been able to arrive at any decisive result respecting it with regard to Clubiona, although the latter appeared to us more probable from analogy. Of some importance in this respect are our observations on the developement of the spermatozoa in a large species of Epeira. The seminal cells measure { fig. 374. a) -^^-o"\ the Fig. 374. Developement of the spermatic cells of Epeira. nucleus which they contain ^Jo^'^ The cells are enclosed in larger cysts {o^-^'^' — -sV'^O J but besides these there is also no want of in- dividual solitary cells. The most interesting circumstance con- nected with this is, that the spermatozoa are produced quite distinctly in the interior of the nucleus of the spermatic cells. At first they are lying (b) like a bent cylinder at the interior surface of the wall, so much bent that both ends nearly touch each other. We have never perceived a change of shape in the nucleus, nor does the same ever or anv where penetrate beyond the cell. It constanth re- mains round, and in the interior of the cell, until it is dissolved, which takes place pretty rapidly after the formation of the spermatozoa. The spermatozoon now arrives in the cavity of the cell (c — f), where it increases in size (to Too'''); It usually exhibits here some slight and irregular windings, u hich sometimes change the form of the cell into an oval. The spermatozoon only becomes free afterwards, when the membrane of the cell has disap- peared. It is only if the external cyst hapj)ens to persist that the spermatozoa still remain enclosed for a time (h), but always in a greater number, which naturally is equal to the number of the cells formerlv contained in 49S SEMEN. it. A tail part we have, however, never been able to discover in the spermatozoa of Epeira. The form was uniformly cyhndrical, and of a tolerable thickness, similar to the body in the spermatozoa of Clubiona. Quite the same mode of developement of the spermatozoa we have also found in one species of Theridimna. It can be traced that it does not deviate at all in the forma- tion of its spermatozoa from other animals. But even the process of developement in Clu- biona, which we have described, does not exhibit any very material differences, which is proved by the observation, instituted by us in a small Dysdera, as also in Tegenaria domestica. The mode of formation of the spermatozoa, in fact, in these instances, occu- pies almost the medium between the former two. In Dysdera the spermatic cells containing the nucleus {Jig. 375. a) measure only sho'''- Fig. 375. Spermatic cells of Dysdera, They are round at first until the nucleus elongates itself, enlarges, and finally assumes a kidney form, the external cell taking on the same shape (b, c,d). One end of the nucleus not unfrequently projects outwards (e), but never in so striking a manner as in Clubiona. The same changes of shape are exhibited in the nucleus in the seminal cells of Tegenaria, which measure -^ho'^'i ^hey, however, never lose their original round shape in the course of the change. We have not been able to discover filiform spermatozoa in the two last-mentioned spiders ; but we nevertheless believe that they likewise occur here, as in Clubiona. Respecting the spermatozoa of the Acarhice, we have as yet had but few observations ; it appears, however, from the statements Ox V. Siebold, that similar stages of develope- ment take place as among the genuine Araneae. V. Siebold observed in the testicles of Ixodes ricinus a large number of rather long and large rod (^After Frey and Leuckart.^ ally project outwards (b, c). The number of the fibres thus formed is generally Umited to one. We have, however, seen cylinders which contained three or four (c). The formation of the spermatozoa in the radiating cells of the other Decapods, in our opinion, takes place in the same manner. Judging from analogy with Mysis, at least, we cannot share the conjecture of KoUiker, that the rays would simply drop off and change into spermatozoa. It appears to us much more probable that they are pro- duced, as in Mysis, in the interior of the cell, and that the growing out of rays is merely a secondary event, caused by the circumstance that the spermatozoa formed in the interior urge the external membrane forward with one end, and ultimately pene- trate through it. The projection of the semi- nal fibres, in Mysis, from the cylinder, has indeed much the appearance of their growing out into a thin and long appendix. Thus much respecting the remarkable semi- nal corpuscles of the Decapods. We must still, however, mention the circumstance that the radiating cells in the lower division of the testicles, or in the vas deferens, are generally still enclosed by peculiar spermatophora, like capsules, which possess a round or oval shape, and are often attached, by means of a solid peduncle, in great numbers, one behind another, to one common round or flat jelly- Ike mass. The spermatozoa in the other orders of the Malacostraca, the Awpkijwda, and Isopoda, are uniformly filiform. Their developement takes place in the usual way, v»^ithout the intervention of radiated cells. The length of the spermatozoa, in most cases, is very considerable : in Hyperia medu- sarum in Iphimedia obesa in Idotea tricuspidata tV'^ Gammarus Pulex aV^^- The thickness, on the other hand, is compa- ratively only slight, being most considerable in the centre, whence the fibre gets gradu- ally thinner towards both ends. KoUiker describes, in the spermatozoa of Iphimedia and Hyperia, a thicker cylindrical and oval end, like a peculiar corpuscle. V. Siebold does the same with regard to Asellus aqua- ticus. We beUeve, however, that such an Fin. 384. Spermatozoa of Gammarus Pulex. appendix {Jig. 384.), or this so-called corpus- cle, is merely the adhering remainder of the mother cell, from which the spermatozoa pro- ject. Of this we have convinced ourselves in Gammarus Pulex. It is certainly difficult to distinguish the seminal fibre in the interior of it, but it appears to us that our observa- tions are sufficient to render doubtful the interpretation of KoUiker, when we consider that this corpuscle occupies so variable a position with respect to the fibre, now lying in the same line with it, and at other times passing into it at a larger or smaller angle, quite in the same manner that we have ob- served in the cylinder of the seminal corpuscle of Mysis. The variable shape of the body, which KoUiker describes in Hyperia, and which we have also found, although less remarkably so, in Gammarus Pulex, might also speak in favour of our opinion. The formation of the seminal fibres in the Oniscidce, according to our observation, also takes place in the interior of transparent cells*, which reach -^^-'^ — ^^o''', and fill up by their number the sacs of the testicles. As soon as the developement of the spermatozoa has commenced in the interior, the cells grow to the extent of -^o^'\ and in so doing assume an oval shape. The contents then usually become rather granular, but the windings of the transparent spermatozoa can nevertheless be recognised now and then. The vesicular seminal elements of Gammarus Pulex, on the * The large egg- shaped corpuscles (of -L' ') which possess, besides nucleus and nucleolus, dark gra- nular contents, and which form the epithelium of the vas deferens, but Avhich are wanting in the genuine seminal tubes, should not be confounded with these seminal cells. Similar cells, only smaller (of about ^go'")' likcAvise found in the spiders ; but, although they occur in the seminal cor- puscles of the palpi, they are not in any way con- nected with the production of the spermatozoa. 496 SEMEN. other hand, are cell formations, which de- velope a seminal fibre in the interior of the enclosed nucleus. Of the same filiform shape, and probably also of the same mode of developement, are the seminal fibres of the Pychnogonides, which, according to an observation of Kolliker, mea- sure upon an average about -^q"' in Pychno- gonura Balaenarum. Equally filiform and also pointed at both ends, are the developed spermatozoa of the Fig. 385. Developement of the Spermatozoa in Chthamalus Philippii. (After Kolliker.') Cirripeds, the size of which, in Chthamalus Philippii, amounts to about rV^''. They are produced from smaller nucleated cells (of — -5ho"% which would seem, from ex- ternal appearances, simply to grow out into seminal fibres {fg. 385.). An exact research into the mode of their production is prevented by the smallness of the cells ; but we need the less hesitate in inferring the usual en- dogenous mode of formation, since we know how often spermatozoa, on liberating them- selves from a mother cell, present, in a mo.st deceiving manner, the appearance of vesicles that are growing out. Little is as yet known respecting the spermatozoa of the Entomostraca. Here also, however, the usual filaments occur in the seminal liquid, in some instances. This may be proved in the genus Cypris, in which such formations can readily be traced.* They are of a considerable length (about V"), and usually wrapped up in the shape of a reel. Such a form of the spermatozoa does not, however, seem to be the only one among the Entomostraca. V, Siebold-\, in Daphnia rec- tirostris, describes oblong semilunar sper- matozoa, whilst Cyclopsina, and probably also Acanthocereus J, possess small finely granular corpuscles of an oval shape, as the elements of the semen. Similar corpus- cles one of us {R. Leuckart with Dr. Frey§,) * We beg to direct attention to the simultaneous appearance of eggs together Avith the spermatozoa in the same individual ; and therefore to tlie her- maphrodite condition of the genitals in Cypris. t Yergleich : Anat. S. 483. j According to Scholler, in Wiegman's Archiv., 1846, Th. i. S. 367. § Ibid. p. 135. has discovered in Caligus. The production of these elements, which could be observed in the latter case, is the same as in luliis. They at first appear as roundish nuclei in the in- terior of the seminal cells, which have a size ofaW — sW''- At this period the nuclei measure s^'" ; they subsequently grow, change their shape to an oval, and in so doing not unfrequently project outwards a little be- yond the cell wall. Vesicular seminal elements are also pos- sessed by Branchipus*, and oblong cylin- drical corpuscles by Staurosoma.f In their passage through the vas deferens, the spermatozoa in Cyclopsina, as well as in the Cephalopoda, &c., are enclosed by one common jelly-like spermatophore. In some other cases, on the other hand (as in Onis- cus), the spermatozoa unite into long flat rib- bon-like strings (of V^^), which present quite an uniform structure, betraying at the ends only that they are composed of separate semi- nal fibres. J Annelida. — The spermatozoa, in the divi- sion of the Annelida, also possess very gene- rally a hair-like form, excepting among the Nematoda. They are thin delicate fibres, ge- nerally without any very considerable length (in Hirudo ^o'^', Planaria varicosa ^V^'j Branchiobdella, on the contrary, quite ^"^), which are either pointed towards the ends, or every where equally thick (in the Tre- matoda, Acanthocephala, and Cestoidea), or enlarged at one end. In Lumbricus {Jig. 386. a) the enlarged part is of an oblong cylindrical form ; in the Nemertinae (b) and the branchiated Annelida, Fig. 386. Spermatozoa of Lumbricus (a) ; of Nemertis Ehren- berqii (b) : and Planaria verrucata (c). (After Kmiker') WW on the other hand, they are round or pear- shaped. In some few cases the spermatozoa among the Annelida exhibit some spiral twin- ings ; as, for instance, in Planaria verru- cata (c), Leptoplana atomata, and especially * Frev and Leuckart in Wagner's Zootomie, 2d edit. Part II. p. 259. f Will in Wiegman's Archiv., 1844, Th. I. S. 340. X Vide Siebold in MUller's Archiv. 1836. SEMEN. 497 in the Branchiobdella. In the latter, these windings are, however, confined to the anterior half ; but they are so close and numerous that they formerly gave rise to the erroneous opinion of one of us*, namely, that the fibres of this part were jointed or articulated. These fibres are in all cases produced separately from small cells, containing nuclei (generally of ^^o'^^ — soo^^0> which lie together in round masses ; being generally situated on the circumference of a large central ball among the bristled worms and Hirudines, as among Fiff. 387. Developement of the spermatozoa in Lumhricus. the Helicinae {Jig. 387. a,). According to analogy with the higher animals the sperma- tozoa are also unquestionably produced in an endogenous way, and, as is shown by the ob- servations KoUiker\ on the developement of the spermatozoa in Lumbricus and Distoma, in the interior of the nuclei. We cannot, however, trace the process of formation with decisive certainty owing to the smallness of the elements in question. The external ap- pearance (b) leads us, however, to infer that the cellular formations grow out into a long fibre. The cells gradually assume a fusi- form shape, but still remain united toge- ther in one group. It is the peripheric end which seems to get extended in forming the spermatozoa. Wherever a central ball oc- curs, for instance, in Lumbricus and Hirudo, the group of cells at this stage of the deve- lopement presents a very pretty appearance. The spermatic fibres radiate towards all directions from the central ball, into which their thickened extremity is inserted; they have then made their exit in a still imperfect state (c). They soon, however, get grouped together into bundles, the points of the fibres gradually converging towards one common point (d) ; the central ball in the mean time gradually dissolves. Similar fasciculated groups are likewise seen in the spermatozoa of Annelids in most cases even where the central ball is wanting — in the Trematoda, &c. for in- stance. The same facts we have already noticed when speaking of the Gasteropoda. We then proved that the separate elements in the groups of cells originate through the continued en- * Wagner in Miiller's Archiv. 1835, S. 222. t Kolliker, Die Bildung der Samenfaden, u. s. w. S. 37. VOL. IV. dogenous formation from one single, and at first simple, cell. It is easily traceable that the same takes place in the Annelida, when we compare the different constituents of the semen, for instance, in Lumbricus. Here, as in the Gasteropoda, we meet with nu- merous formations, which in one continued series of transitional developement lead to the form of groups of cells, taking their origin from one single nucleated cell containing some brownish granules. In tlie interior of this cell numerous daughter cells are produced, the number of which continually increases. Finally the wall of the mother cell bursts, the enclosed cells become free, and deposit them- selves around the remainder of the cellular contents, which latter have not participated in the formation of the daughter cells. Whenever the central ball is wanting in the group of cells, the mother cell generally gets destroyed at an earlier period. This view is supported by an observation of Kolliker, from which it appears that the groups in Spio con- sist at first only of few and large cells, which subsequently increase in number whilst their size decreases. It is impossible, however, to draw a very strict boundary here. Even in the former case the increase of the daughter cells frequently seems to take place after the membrane of the mother cell has been destroyed, which may also be seen in the Helicinae. In other cases the mother cell not only survives the endogenous formation of daughter cells, but also the process of the developement of the spermatozoa. We are at least led to this inference by the observations which we had the opportunity of making in some small species of Terebellaria from the North Sea, namely, that the bundles of spermatozoa are sometimes still enclosed by one common oval cyst. Bryozoa. — A similar series of phenomena we Fig. 388. Spermatic cells of Flustra carnosa; (a) still con- tained in the mother cyst ; (b) partially free. find in some Bryozoa (which would be perhaps Fis. 389. Developement of the spermatozoa of Flustra carnosa. (^After Kolliker.) most correctly classed among the Annelida), for instance, in Laguncula and Alcyonella*, * Yid. Von Beneden in the M^rn. de I'Acad. de Bmxelles, torn. xv. and xviii. K K 498 SEMEN. whilst the formation of the spermatozoa in others (for instance, in Flustra, Erisia, Bowerbankia) only commences when the separate cells of developement (b) have be- come free through the destruction of the large (tW^^ — tVO cyst-like mother cell {fg. 388. A.). The spermatozoa even here, how- ever, are produced by the apparent growing out of the small cells of developement (of -gL-^'^j containing nuclei (see fg. 389.). When developed they are linear and proportion- ately thick and long (in Flustra about oVO' and frequently, it seems, furnished with a roundish or oval corpuscle. Roiifera — The spermatozoa of the Rotifera, at least of iSIegalotrocha, have a similar pin- like form, if we may judge from the observa- tion of KoUiker^,vih\c\\ is the only one before us, and this does not seem to be quite decisive. His statement, that these formations had par- tially been fixed in the interior of the cavity of the body, makes us at least look upon his observations with mistrust, and leads us to suppose that the}' have been confounded with the remarkable vibratile organs, which are certainly not spermatozoa. Xul/i/cer's observa- tion, however, is interesting, inasmuch as he also states that those fibres are apparently produced through the growing out of small solitary cells. Speinnatophora have not yet been met with in the division of the Annelida. On the other hand, however, we have observed that the spermatozoa in some species of Saenuris (Tubifex) unite into transparent homogeneous strings (as in many insects) in their passage through the vas deferens. These formations have a cylindrical shape, almost vermicular, getting thinner towards both ends. They are also not unfrequently met with in the recepta- culum seminis of the female apparatus. A simi- lar mode of grouping seems to take place with regard to the spermatozoa of the Hirudines, in the so-called secondary testicles. The sper- matozoa of the Nematoda (excepting the paradoxical genus Pentastomum, in which we find the ordinary linear spermatozoa ) possess very deviating shapes. They consist of a roundish or oval corpuscle of about 3-00"^ and a short rigid peduncle, which projects more or less outwards, and has a varying thickness (^^r. 390.). The spermatozoa in the very same formations again, in a perfectly unchanged shape, in the female individuals. We must therefore characterise Ku/li/cer's supposition of these corpuscles being mere stages of developement of seminal fibres, as one that cannot be relied upon. The developement takes place in the same way as in lulus. At first we find simple cells containing n uclei, which , according to it'e/f/^erf^ researches, are produced in the interior of large mother cells * (fg. 391.). The nucleus Fig. 391. Spermatic cell of Ascaris acuminata, with four vesicles of developement. (A fter Reichert.) has at first a roundish shape {fg. 392.), but gradually stretches itself more and more, and Fig. 392. Developement of the spermatozoa of Ascaris acuminata. projects 'more or less outwards with its point, thus metamorphosing itself into the peduncle-like appendix of the spermatozoa, the body of which is formed from the persisting membrane of the seminal cell. This last circumstance, but %\hich does not in- variably occur, is the only distinction that can be found between the Nematoda and the lulidae. Radiata. — Echinodermata. — The sper- matozoa, in the division of the Echi- nodermata, possess, it seems throughout, a pin-like form {fg. 393.), with a small Fig. 393. ] Fig. 390. Spermatozoa of Sti'ongylus auricularis. {After Reichert in Midler's Archiv. 1837. Tab. VI.) Gordius appear in the shape of short rods without any corpuscles. We cannot doubt that these seminal ele- ments are developed spermatozoa, havino; sought in vain, and for a long time, for other forms of developement, and having found * Froriep's Xeuen Xotizen, S. 59G. Spermatozoon of Holothuria tububsa. roundish body (of eiso'")^ ^^d a very slender tail appendix of about — -5^'^'. It is only in rare cases (as Spatangus} that the body has an oblong form, and is rather pointed at the anterior end. The developing cells of these spermatozoa are very small, and lie in groups, as in the Bryozoa, inclosed in large cyst-like mother cells. The developement of the spermatozoa undoubtedly takes place according to the usual mode, although it cannot be proved with certainty, and although the appearance * Mullet's Archiv. 1847, S. 88. SEMEN. 499 seems rather to indicate a gradual elonga- tion of the cells. The spermatozoa He to- gether in bundles, either enclosed by the cysts or free. Acalephcs and Anthozoa. — The Acalephaeand Anthozoa exhibit quite a similar series of phe- nomena. The bodies of the spermatozoa are usually round, frequently however, especially among the Medusae (^g. 394.), oblong, cy- Fig. 394. Spermatozoon of Pelagia denticulata. lindroid. Little is as yet known respecting their developement. The spermatozoa have generally a fasciculated style of grouping together, and mostly so at a j)eriod when they are still enclosed by cyst-like cells. Pre- vious to the maturity of the generative capa- city, these cysts contain, as has been proved with regard to the Medusae, numerous small vesicles, which subsequently pass through ap- parent prolongation into spermatozoa. Infusoria. — The Infusoria are especially distinguished by the want of a sexual mode of propagation. There is no trace of either spermatozoa or ova to be discovered in them. Ehrenherg, it is true, describes in these animals particular organs of procreation, both male and female ; but there is no foundation for the assignment of such an import to these particular parts of their structure, it being altogether an arbitrary one. The proof of the existence of spermatozoa and ova — the ' characteristic structures — is indis- pensably necessary to prove the embryo-pre- paring function of certain parts, and to justify their being interpreted as generative organs. Goieral conclusions respecting the morphology and developement of the spermatozoa. — A re- view of the description now lying before us, of the form and developement of the seminal ele- ments in the several divisions of the animal kingdom, and of the mutual relations of the respective formations, must unavoidably lead us to claim for them a different morphological value. By far the greater part of the spermatozoa, — all the so-called seminal fibres, which are distinguished by the linear form of the body, — are produced in an endogenous way, and that (with the exception of the spermatozoa in the Decapoda) separately in the interior of vesicular elements. KolliJcer* was the first who directed attention to the wide exten- sion of this mode of production f, hav- * Die Bildung der Samenfaden. t Tlie doubts which Reicliert recently raised against the correctness of the statements and obser- ing claimed it likewise for such animals, in which appearances are rather in favour of an immediate metamor()hosis of the vesicles of developement into seminal fibres (by means of elongation, growing out, &c.). The laws of auc.logy certainly justify us in drawing the same inference as KoUiker ; the more so, as observation has proved that many animals, the developement of whose spermatozoa was formerly accounted for by the latter me- thods, evidently also follow the endogenous It IS difficult to trace the intimate develope- ment of the spermatozoa in the interior of these vesicles ; but it appears probable that it is brought about by the junction of molecular corpuscles, which join each other linearly, and which have been deposited from the con- tents of the vesicles. Indeed, such a mode of procedure does not seem to be at all sin- gular in the history of developement of organic tissues. By saying this, we do not exactly mean to allude to the mode of formation of the muscular fibrils in the interior of the sarcolemma of a so-called primitive fasciculus, since at present we know too little about it ; yet, we cannot help reminding our readers of the process of lignification in the vegetable world, or of the production of the so-called spiral vessels, which essentially seem to be founded on a perfectly analogous deposit of a firm substance, from that which was at first fluid. The decision of the question respecting the histological significance of the vesicles of de- velopement is much more difficult. In many cases, especially when they are situated sepa- rately or in small numbers in the interior of the spermatic cells, they have evidently the value of nuclei. Whether this however is always and every where the case, as Kollikei- supposes, we would not assert ; the less so because the appearance and the vesicular form of these structures do not by any means enable us to distinguish them properly from cells void of nuclei. By the laws of analogy, we are, however, perhaps justified in forming a judgment on the nature of the respective elements even in such doubtful cases. We ourselves might perhaps even venture to pronounce that the vesicles of developement of the spermatozoa are in all cases nuclei. The unity in the mode of developement of the spermatozoa which would thus be established is certainly very attractive; but we dare not conceal it from ourselves that this inference from analogy is the less to be depended upon, since the genesis of the spermatozoa in the Decapoda furnishes us with a proof that the formation of these elements may also take place imme- diately in the interior of cells, without the nuclei at all participating in it. We are confirmed in this opinion from the circum- stance that in many Decapoda, for instance in Mysis, it is not the cell itself in which the spermatozoa are produced. The cylindrical vations of Kolliker we certainly must consider as entirely unfounded. K K 2 500 SEMEN. staff, in the interior of which the spermatozoa are developed, is the produce of the metamor- phosis of this cell ; a metamorphosis which here appears in its extreme form, but which in other cases is less striking, and may even be entirely wanting. And then it is the cell in its unchanged form which appears as the vesicle of developement of the spermatozoa. Under such circumstances it might for the present be venturing too much to sever the mode of developement of the spermatozoa in the Decapoda, as a particular form, from the ordinary endogenous formation of these elements. We are not justified in so doing, until we have proved that in other animals mere nuclei exist as the mother cells of the spermatozoa. It is possible that such a proof may yet be established, indeed even probable, when we consider that there is also in other respects a difference in the formation of the seminal fibres between the Decapoda and other animals, inasmuch as the vesicles of developement in the former generally and almost constantly produce a greater number of spermatozoa, whilst in other animals they only produce a single fibre. As a circumstance of subordinate import, which need not influence our judgment re- specting the nature of the vesicles of de- velopement, we may specify a difference in the histological characters of these parts, which certainly at first sight must appear very striking. We meet with them either in an independent free state, or separate, or en- closed in a variable number within cells, which themselves not unfrequently hang to- gether in groups, or are even situated in a cyst-like enclosure. But all these differ- ences result solely from a different develope- ment and application of all the plastic capa- cities inherent in the cells. They are due to the occurrence of an endogenous multipli- cation, and are readily explained by the in- timate unity and connection which this method of developement presupposes. The formative elements of the semen ap- pear to us in their primitive form as simple nucleated cells. But it is only rarely that they retain this original form. As a rule they present only the starting point of a series of metamorphoses, which essentially are limited to a new formation of nuclei, or even of perfect nucleated cells in the interior of the primitive spermatic cell : a new Ibrm- ation, which, however, not unfrequently oc- casions the destruction of the mother cell. It is not yet decided in all cases in what manner the formation of the daughter cells takes place, whether in the usual mode of endogenous cell formation, or by enclosure of portions of the contents. It seems, how- ever, that the former mode of production is by far the more frequent one. Reichert has been the only one who has hitherto dis- covered a formation of daughter cells round portions of the contents (like the forma- tion of cells in the minutely divided yolk) in the spermatic cells of the Nematoda. If such discovery should be confirmed — should it even have a greater extension — we may then further presume (as Kolliker already observes) that these two modes of develope- ment are not essentially different from each other. The description we have just now given may, at all events, be sufficient to prove of what a merely subordinate significance are these differences in the histological arrange- ments of the formative elements in the seminal fluid. By a series of intermediate stages, we can almost every where readily trace the con- nexion in which the arrangement of the vesi- cles of developement stands with the simple primitive spermatic cell. Such a relation, however, is not only interesting on account of its enabling us to recognise an internal typical structure and developement of the seminal contents, and that in spite of their external variety, but also because we thereby discover that the primitive form of the male procrea- tive elements is precisely the same — namely, a simple cell — as that of the female gene- rative product, which is designated " the ovum." Having thus, by our preceding researches, arrived at the result that the developement of the spermatozoa always and everywhere ori- ginates from the same primitive formation, namely, from the simple cell, another question now arises, viz. the question respecting the relation of this simple cell to the epithelial lining of the seminal tubes. This claims our attention the more, as our conception of the epithelium, within a re- cent period, begins to be more and more indefinite, owing to the accumulation of ob- servations, by which the so-termed epithelial cells of the glands have been proved to be mere vesicles of secretion, the workshops for the preparation or expulsion of the products of secretion. The recognition of the connexion of the spermatic cells with the real epithelial cells is rendered very difficult by the various meta- morphoses of the former in the tubuli seminiferi. Nevertheless, some observations that have been made may perhaps akeady justify the inference that the simple spermatic cells are, in many instances, at least, identical with the so-called epithelial cells of the se- minal tubes. This appears with particular distinctness in the Gasteropoda, in which Meckel* and Kol- liker have already assumed such a relation, without, however, pronouncing it with that degree of certainty which our observations enable us to do. We may as readily con- vince ourselves of this fact in the Annelida, in Hirudo or Ascaris, as also in the In- sects, Spiders, and Arthrostracans : it being evident in all of them that the spermatic ceils constitute the only vesicular contents of the testicles, and form, in their primitive shape, a complete epithelial layer, the ele- ments of which frequently even assume a polygonal shape by close adaptation to each other. * Muller's Ai'chiv. 1844. SEMEN. 501 This connexion is, however, least distinct among the higher Vertebrata ; in which, inde- pendently of the spermatic cells which exist free in the semen of the seminal canals, there likewise occurs a special and generally well developed stratum of epithelial cells, which are distinguished from the former by size and appearance. But this arrangement is only to be met with during the period of generative maturity. Previous to it, free spermatic cells do not exist, and the canals of the testicle have then uniform contents, con- sisting of small cells of of a line in dia- meter,, in which one or two small granules are contained. We have not been able to trace the history of the real seminal cells, but we do not consider it as altogether impro- bable that they are produced from the former epithelial cells, and most likely are developed in an endogenous manner. The possibility can certainly not be denied, that they may have been produced independently and free in the interior of the seminal canals. But even in this latter case it is unquestionable that the vesicle in which they develope themselves is furnished by the epithelial cells and has formerly been contained in their in- terior. The difference even in this instance, therefore, would not be so very material,- and might be reduced to a mere difference in the periods of formation. In both cases the seminal cells might be assumed to be produced from the contents of the epithelial vesicles, either at a period when such contents are still contained in the interior of them, or after they have become free. Our preceding remarks respecting the his- tological relations of the seminal cells apply in an equal measure to ail animals, and not merely to those the spermatozoa of which possess a linear form and are produced in the interior of the vesicles of developement. The Ghilopoda, Acarina, Entomostraca, and Nematoda furnish ns with sufficient proofs of this, — proofs which contradict the as- sumption of Koiliker*, that a linear form of spermatozoa is common to all animals. Al- though many of the differently-shaped seminal elements may, after a more accurate research, be proved to be mere forms of developement of the real spermatozoa, even this cannot be asserted with regard to all of them. These differently- shaped seminal elements are the very ones that here more particularly concern us ; we know that they differ in their develope- ment from the ordinary seminal fibres. They are solid massive corpuscles, which, as we have already shown, have been produced simply and immediately from a metamorphosis of nuclei. But even here it is the nuclei of the seminal cells, which serve for the developement of the spermatozoa. The whole difference consists in this, that the nuclei are metamorphosed altogether into the fructifying elements of the semen, whilst otherwise they produce the spermatozoa in the interior, they themselves * Page 63, getting dissolved when the latter arc about to be liberated. The external cellular mem- brane which encloses these nuclei remains, however, without any immediate participation in the formation of the spermatozoa. It gets^ destroyed in the course of the developement, in order to enable the nuclei, which in the mean time liave been converted into sperma- tozoa, to make their exit. This at least holds good in most of these cases, the Nematoda only being an exception. The membrane of the cells belonging to the metamorphosed nuclei, persists in the latter-named animals. According to this we have a threefold mode of developement of the spermatozoa, viz. : — 1st. The cell membrane and nucleus of the formative vesicles convert themselves imme- diately into the spermatozoon. 2d. The nucleus of the formative vesicles alone metamorphoses itself into the sperma- tozoon. 3d. A new formation, which takes place m the interior of the nucleus (or immediately in the cell cavity), performs the functions of a spermatozoon. On comparing the spermatozoa developed in these different ways, we cannot deny that they have a different stage of developement in a morphological point of view. The sper- matozoa resulting from endogenous forma- tion are most highly developed ; they are the produce of a perfectly new generative process-, whilst the other forms of spermatozoa owe their origin to a persistency and further developement of structures, which, first of all, were mere transitory elements, and were onlv of importance as the seat of that neoplastic process. Under such circumstances we may assume, then, that all these forms of sperma>- tozoa, according to the morphological relf^ tion in which they stand, are mere different stages of developement in one common con- tinued series, — mere variations of one thema, in which the differences seen are not essen- tial, but only of a relative import. Taking; into consideration this unity, we cannoi^ agree to the objection tliat may possibly be made to us, as if we had described the spermatozoa (which, essentially and in fact,^ are identical formations) to have been pro- duced in different ways. The mutual rela- tion of these differences is in perfect unison with the laws of organic architecture, whirh every where (when a common plan is made the basis of a series of formations) exhibits the variety of the concrete form principally through a variable developement and perfec-. tion of the ideal type. It might not be without interest to re-< fleet upon the important part which the nucleus plays in the formation of the sperma- tozoa, since it is an element which is usually only important for the form,ation of cells, and does not participate in their subsequent me-? tamorphoses. This at least is the rule ; a rule, however, by no means without excep- tion. We already know that in many cases the nucleus is important for the developement of certain parts ; we know that the nucleus K K 3 502 SEMEN. in many glandular cells of the insects gra- dually assumes a remarkable ramified shape * ; and that it even converts itself in other cases into peculiar fibrous formations — into the so-called nuclear fibres (Kernfasern).f Still more remarkable is the metamorphosis of the nucleus in the developement of the so- called prickle or nettle organs — those in- teresting microscopical formations, which are so frequently imbedded in the skin of the lower animals (e. g. Polyps and Medusae), and which present so great a similarity to certain forms of the seminal fibres, that they were even taken for such by one of us on their first discovery. Kolliker'sX observa- tions, as well as our own more recent ones, instituted ui)on Hydra, convince us beyond doubt that it is the nuclei of cells which gradually metamorphose themselves into the capsules of the prickles, and which ultimately become free through the dissolu- tion of tlie cell membrane surrounding them. The same genetic process therefore takes place here in every essential point of view, as that by which the formation of the sperma- tozoa in the Chilopoda is effected. But the developement of the prickles is never limited to this metamorphosis of the nucleus. There is formed at the same time in its interior ti peculiar linear or fibrous part, which how- ever constantly enters into combination with -the persistent external vesicle of the nuclei or with the capsule. Thus we may see that the formation of the prickles is closely con- nected with that scheme which we have laid down as a formula for the developement of the spermatozoa. It occupies the medium be- tween the second and third mode of de- velopement of the spermatozoa established by us. On examining the external coverings of Hydra, we shall readily be enabled to con- vince ourselves of the formation of these organs. The most different stages of de- velopement may here be seen, viz. developed prickles, either free or still enclosed by a cell membrane, from which the organ it- self, and especially the fibre enclosed in its interior, recedes more and more, until it finally appears as a mere simple nucleus. In several Planariae the organs are con- tained, in an imperfect state, in considerable numbers in one common cell. The nuclei in the interior of the cells have therefore multiplied here, as in the seminal cells of the vertebrata. Organization of the spermatozoa. — At the period when the spermatozoa were still con- sidered as individual animated creatures, it was natural that those qualities should be sought for, which distinguish animals gene- * According to tlie discovery of Frey and Lenc- kart (Wagner's Zootomie, ii. p. 61.), which sub- sequently, has also been made by H. Meckel (Mul- ler's Archiv. 1846, S. 26.). f Yid. Henle (Allgemein. Anat. S. 193.) and ZAvicky (Metamorphose der Thrombus). \ R. Wagner in Weigmann's Ai'chiv. i835. rally ; and it was frequently asserted that the distinct traces of an internal organization had been found in them. Even Leuwenhoek^^ the oldest observer of these structures, de- scribes in the body of the spermatozoa of the ram and of the rabbit, indications which were subsequently interpreted by Ehrenberg \ and Valentin \ to be intestines, stomachic vesicles, and even generative organs. Other histologers, for instance, Schwann and Henle, thought themselves justified in calling a dark spot, which shows itself occasionally in the body of the spermatozoon in men, but which is decidedly a mere accidental formation, as a suctorial cavity. But all these statements are now no longer believed in, as our present knowledge of the developement of these form- ations has entirely removed the idea of their parasitic nature. Indeed the subject requires no further refutation, as an unprejudiced ob- servation will prove that the spermatozoa are every where void of a special organization, and consist of an uniform homogeneous sub- stance, which exhibits, when examined by the microscope, a yellow amber-like glitter. The above mentioned investigators have by this time undoubtedly seen their error. Motions of the spermatozoa. — The opinion of an internal organization of the developed seminal elements was not a little supported by the various remarkable phenomena of motion, which were frequently perceived in them. In former times, when people had no idea of the existence and extent of the so- called automatic phenomena of motion, which take place without the intervention or in- fluence of the nervous system ; when nothing was known of the motion, very similar to a vo- luntary one, which exists even in plants ; this movement was certainly calculated to place the independent animal nature of the spermatozoa almost beyond a doubt. But it is different now. We now know that motion is not an exclusive attribute of animals, and that an in- ference respecting the animal nature of the formations in question, however similar the motion observed in them may be to that of animal organizations, is a very unsafe and venturesome one. We know that certain elementary constituents, animal as well as vegetable, possess a power of movement, and that they even retain it for some time after having been separated from the organisms to which they belonged. We only here need remind our readers of the so-called ciliated epithelia, the severed cells of which swim about in the fluid surrounding them, and which, when in this state, have not unfre- quently, and that even quite recently, been considered as independent animals how, * Opera, vol. iv. pp. 168. 284. f Infusoriensthierclien, S. 465. j Xov. Act. Acad. Leopold, vol. xix. p. 239. § For instance, Xordmann , has described the severed ciliated cells from the sails of the larvae of Xudibranchiata as parasitic Infusoria (Cos- mella hydrarhaoides). (Versuch einer Mono- graphic der Tergipes Edwardsii. Petersburgh. S. 97.) SEMEN. 503 further, the spores of the algae possess motion by the aid of a ciliated investment*, or of a single or manifold long whip-like fibre, until they eventually become fixed, and develop themselves into a new plant.f Such spores as these may be found described and illustrated in the well-known magnificent work o( Ehren- berg, classified as Infusoria under the groups of Monadina, Volvocina, &c. Under such circumstances we may consider ourselves perfectly justified in declaring every attempt to prove the parasitic nature of the spermatozoa, by the characteristic of their peculiar motions, as futile and inadmissible. Developement, structure, and composition are the decisive characteristics in this respect, and these prove the fructifying elements of the semen to be mere elementary constituents of the body in which they are formed. The motions of the spermatozoa are therefore in their essence identical with the above men- tioned automatic motions of cilia, &c. But the knowledge of the movement of the sperma- tozoa will always be interesting and impor- tant ; because, of all these phenomena, it is undeniably most closely connected with the locomotive motions of animals. We must not, however, lose sight of the fact, that these motions are not possessed in equal perfection by all spermatozoa, but that in many cases they are scarcely visi- ble, and hardly equal the motions of the cilia. Indeed there are many spermatozoa which are perfectly motionless, particularly all those forms which owe their immediate origin to a metamorphosis of the nucleus, or of the wall of the primary cells. Only those spermatozoa which have been produced by an endogenous and new developement arecapable of independent motions, and even not every one of these. No such movements have as yet been perceived in the spermatozoa of the Malacostraca (Isopoda and Amphipoda). They appear motionless and rigid. The same holds good with regard to the body of the spermatozoa when it has a short, round, or pyriform shape. It never then participates in the motions, which are in such cases altogether effected by the thinner, whip- like, caudal extremity. It is different, how- ever, with those spermatozoa which pos- sess a cylindrical body. The body here par- ticipates in the motion ; at least very fre- quently, as, for instance, among the scaly amphibia, among the birds (excepting among the singing birds), &c. But the motions of the body are less rapid, energetic, and various than those of the tail. They are principally limited to a bow-shaped curvature, similar to the motion of the Vibriones, which, like the Monadina, belong to the vegetable kingdom, and may undergo a further developement into fibrous fungii * Vid. Unger, Die Planze im Moment der Thier- wendung ; also Von Siebold, Dissert, de Finibus inter Regnum Animale et Vegetabile constituendis. t Fresenius, Zur Controverse iiber die Yerwand- lung von Infusorien in Algen. In order to observe the movements of the spermatozoa properly, they ought to be in- vestigated under different circumstances. On putting a drop of thick semen from the vas deferens under the microscope, a slow mo- tion only can usually be observed in the accumulated masses of spermatozoa. They present an appearance as if they had some diffi-culty in disentangling themselves from the tough fluid by which they are sur* rounded. On adding blood serum to it to dilute the mass, the movement becomes more lively, either instantaneously or gradually. Se- parate sjjermatozoa writhe once or twice, turn round on their axis, lash with their tail, and creep about in all directions over the field. The motion gradually imparts itself to greater numbers. Here and there, simultaneously all the individuals of a group begin to move ; or particular parts of the mass commence the movement. The remainder perhaps exhibit no motion, and sometimes this quiescent state is permanent. If the movement of the spermatozoa be rapid, it assumes, for the most part, an accu- rate rhythm like a pendulum. The firli- form tail vibrates like a whip, and the small corpuscle or head follows the impulse. Frequently a peculiar trembling, dancing, or jumping is exhibited by the latter when the rest of the spermatozoon remains fixed and un- moved. A serpentine creeping in all directions is produced during a slow motion, and is caused by an undulating contraction of the caudal appendix. These undulating motions are perhaps the most frequent which the spermatozoa (and even the thread-like forms which possess no visible body) present to our view. They often move in one straight direc- tion, without turning aside, and altogether in such a way and with such a regularity as to resemble the locomotive motions of many of the lower animals. The same regularity is met with in the motions of the long and rigid spermatozoa with a spiral body among the singing birds, which very frequently turn rapidly round their axis, and thereby advance with a screw-like or boring movement. Pendulum-like lateral motions are but rare. Very peculiar and different are the motions of the spermatozoa in the Salamanders, which usually he wrapped up like a watch spring, flat on a level. For a time they remain quiet until suddenly, by fits and starts, a trembling motion takes place, by which they turn them- selves round in a circle, pretty nearly on the same spot. Some few (as the Bombinator) stretch themselves out, and travel with a slow undulating motion over the field of the microscope. The most remarkable pheno- menon, however, consists in a peculiar wave- like motion on the surface, and which is solely caused by the rapid succession of un- dulating motions. We have also perceived a perfectly similar undulating motion in the very long, coiled-up spermatozoon of Geo- philus, which is occasionally so powerful as K K 4 504; SEMEN. to cause the whole fibre to be moved round in a circle. The normal movements of the spermatozoa just described must be distinguished from various other remarkable and irregular pheno- mena of motion which are perceived on treat- ing them with water, particularly in the long and hair-Uke spermatozoa of the Insects, Gas- teropoda, Hehnintba, and Cirripeda, and also sometimes, ahhough in a shghter degree, in those of the Reptilia and Mammalia. !Siebold* was the first who estimated these latter phe- nomena at their proper vakie, attributing to them their real cause, viz. the hygroscopic quality of the spermatozoa. Tliese phenomena take place only on the addition of fresh water, whilst sea water exercises but little influence on the sper- matozoa, which may he accounted for by the difference in the saline constituents of these fluids. This fact, however, is of the greatest importance, in a physiological point of view, because the fecundation of the ova in many marine animals does not take place by copulation, but is accomplished through the transfer of the spermatozoa by means of the sea water, and the influence of this me- ilium should not be such as to destroy the power of motion on the part of the sperma- tozoa. In cases where the fecundation takes place in the same manner in fresh water, for instance in the muscles, the spermatozoa are but slightly hygroscopic, so that their in- tegrity remains undisturbed. These abnormal phenomena of motion, caused by the influence of water, exhibit something similar to that which is seen in a rope turned by a wheel in a rope yard. The -spermatozoa roll themselves out in larger or smaller windings, and form simple or com- pound coils of the most variable kinds. Fre- quently they turn back again after some time, and re-assume their original shape ; they fre- quently also remain in the position they have at first assumed. In short, changes take place every moment. When the fibres lie in a straight position, a number of coils are sud- denly produced; but they disappear equally as quickly, and it is only after some hours, when all the spermatozoa have rolled themselves into these coils, that the movements finally cease. It is interesting that the normal undulating motions of the spermatozoa, where they lie together in regular masses without being able to change their position, very frequently coincide in a remarkable manner, appearing to be carried out, as it were, by one common will. But although this may appear strange jat the first glance, it cannot surprise us when we consider that the same behaviour is ob- served in the ciliated cells. We here see the motions in the cilia of one epithelium regu- lated, as it were, by one common plan ; we observe how these coincide with the move- ments of the cilia of others, and thus unite into one regular motion of the whole. A * Huller's Archiv. 1836, S. 19. peculiarly beautiful sight is afl^orded by the aggregate motion of the spermatozoa in the semen of the earth w orm, w hich resembles the undulating motion of a corn field. Among the insects we have also various opportunities of observing this kind of aggregate motion. A similar aggregate motion is frequently (especially among the Invertebrata) found in the separate bundles of spermatozoa, even when they are still surrounded by their cyst- like enclosures. At first sight it creates an impression as if an undulating fluid were agitated in the interior of the cysts, whilst it is merely the windmg motions of the sperma- tozoa, which follow each other in quick and regular succession, impai'ting the impulse to the whole mass. iNIotion, however, is entirely wanting when (as is especially the case among the insects) the spermatozoa are united into simple and uniform cords. A slight curving or trembling is only observed now and then, which is evidently the consequence of hygroscopic conditions. We know^ as little of the cause of the movements of the spermatozoa as we do, in point of fact, of the remote cause of every mo- tion. But that it depends on certain relations of structure and composition, is evident from the circumstance, that it is wanting in the unde- veloped spermatozoa, only gradually taking place w ith progressive developement. A slight vibration or beating with the tail is first of all observed in them. The most lively, most vigorous, and most combined motion takes place, on the other hand, during the period of rutting, when the developement of the fructi- fying spermatic elements has reached it^ height. But the motion of the spermatozoa is not even then unlimited. The death of the ani- mal in whose spermatic organs they are con- tained, or their removal from it, only allows the motions of the spermatozoa to survive for a time, which, however, is of a different dura- tion in different animals. It seems to be shortest in the birds, where the mot'.on fre- quently is extinguished fifteen or twenty mi- nutes after death ; at least it can but rarely be observed after some hours. In the mam- malia their motion survives some time longer, especially if they remain enclosed in their natural organs. Death, or removal, seems to have a diflferent influence on the spermatozoa of the cold- blooded animals ; among the fishes, for in- stance, they continue moving for da\s after having been expelled from the body. The mode of death of the animals has no influence at all upon the duration of the motion in the spermatozoa. It remains all the same w he- ther the animals are decapitated, strangled, or poisoned. The motion of the spermatozoa survives longest of all in the interior of the female generative organs. The insects (in whom, as in Gasteropoda and some other animals, parti- cular pockets or capsular organs are deve- loped during the period of procreation) furnish SEMEN. 505 the most striking proof of this. The sperma- tozoa, when enclosed in these, frequently re- tain their full vitality for months. Among the mammalia, likewise, the motions of the spermatozoa remain unimpaired in the vagina, or in the uterus, for some days after copulation. The mucous coat which covers these or- gans has no prejudicial effect on the motion and vigour of the spermatozoa*, and equally as little so the addition of other animal fluids, as the secretion of the prostate, the serum, milk, &c. Common saliva, and even bile or pus, does not exercise any impeding influence upon the motions of the spermatozoa. The addition of urine, especially when hav- ing an acid reaction, seems to have a rather more injurious influence upon them, for their motion ceases soon afterwards, although for some hours slight traces of it may still be per- ceived. We have already treated of the influence of common water upon the spermatozoa. Diluted saline solutions or sugar and water, on the other hand, either do not produce these inju- rious effects at all, or, at least, only in a very slight degree. The chemical agents are the only ones which have a positively injurious effect on the spermatozoa, changing and destroying their structure and composition ; as for instance alcohol, acids, metallic salts, &c. Diluted aqueous solutions of narcotic vegetable substances, of strychnia, morphia, &:c., have the same effect as common water. The electric spark destroys the motion of the spermatozoa instantaneously, unques- tionably because it changes their structure. Galvanism, on the other hand, remarkable to say, has no effect upon them, as Prevost states. A high or low temperature hkewise causes the motions to cease, or at least to slacken, although the motions of the sperma- tozoa of frogs and fishes continue when the surrounding medium sinks below zero. The same has been observed in the spermatozoa of Limngeus and Planorbis on treating them with hot water of 70^—80° (Centigrade). Chemical composition of the semen. — The semen in most animals is a tough, thick, white, yellow, or darkish grey fluid, heavier than water, falling to the bottom when shaken with it. Its taste is sharp and astringent. The peculiar smell, which is usually attributed to it, is comparable with the smell of bone filings, and has its origin, perhaps, in the secre- tions mixed with it. Pure semen in man and animals does not seem to give forth any de- cidedly striking smell. The chemical analyses of semen are dated from a period when our knowledge of organic combinations was still very imperfect, and far from having attained that elevation, by which it has become equally important to physiology as the study of morphology. The works of * For numerous researches on the influence of reagents on the movements of the spermatozoa, vid. Donne's Nouvelles Experiences sur les Ani- malcules Spermat., Paris, 1837 ; as well as Krte- mer, p. 17. In some cases, however, our owti re- searches have furnished a different result. Fourcroy^ Vauquelin^ Jordan, John^ and l^as" saigne, are still the sources from which we derive our knowledge of the chemical nature of the semen. Vauquelin, whose analysis is the most elaborate, found in the human semen ninety parts of water, one part of soda, three of phos- phate of lime and chloride of calcium, and six parts of a peculiar substance (spermatine). These statements were afterwards confirmed by John and Lassaigne. Spermatine, however, the more intimate knowledge of which would have possessed the princi[)al interest, was no further investigated than it had been pre- viously by Vauquelin. Under such circumstances it appeared desirable to undertake a new chemical analy- sis of the semen, especially as the former researches had embraced the whole mass, without paying regard to the morphological constituents, or to the admixture of the prostatic secretion. To remove this defect, a series of researches has been instituted by Dr. Frerichs at our request, in the new chemical laboratory of the physiological in- stitute of Gottingen, respecting which the fol- lowing has been communicated to us for publication. The most careful of these analyses was made on the semen of the carp, it being a fish which is perhaps best calculated for an inves- tigation of this nature. The testicles were cut into pieces, and crushed, in order to press out the semen. Thus obtained, it presented a whitish, glutinous, or viscid mass, from which the membranous fragments were carefully removed. The residue of pure semen con- sisted of the spermatozoa, suspended in a fluid, and a few epithelial cells. It was perfectly neutral. The corpuscular parts of the mass of semen were now separated from the fluid by filtra- tion, and both were separately examined. The Jluid was colourless and clear, of a neutral reaction. The fluid at first filtered ex- hibited no coagulation when boiled, nor was it precipitated by nitric acid. Albumen, there- fore, was not present. The liquid which sub- sequently passed through, however, on wash- ing the mass, precipitated a small quantity of albumen on being subjected to a boiling heat, as also on being treated with nitric acid. Acetic acid, tannic acid, alum, and acetate of lead likewise precipitated albumen. On being evaporated, the fluid left a yel- lowisb, gum-like mass with a strong fishy smell. It re-dissolved partially in water, but was precipitated from it by tincture of galls. The insoluble residue was easily dissolved by diluted solution of potash, and precipitated by acetic acid, without being again dissolved by an excess of it. A part of the evaporated semen was burnt : there remained an ash, consisting of chloride of sodium, as also of slight quantifies of phos- phates and sulphates of the alkahes. The spermatic fluid therefore resembles a thin solution of mucus. The spermatozoa which were left after 606 SEMEN. filtration were carefully washed with water : they were thus quite pure, excepting the ad- mixture of some few epithehal cells. The subject used in the investigation had attained full generative maturity, and was almost devoid of vesicles of developement. The spermatozoa were dissolved by cold solution of potash ; a certain cloudiness which remained was due to epithelia that were slowly dissolved. The alkahne solution exhi- bited a copious precipitate on the addition of acetic acid ; but the precipitate was insoluble in the excess of the acid, even by digestion. It was filtered off, and the acidulated fluid treated with potash, iron, and cyanic acid, but no cloudiness was produced. The sub- stance of the spermatozoa coincides, therefore, with the " binoxyde of protein" of Mulder; it contains no albumen or fibrin. A part of the spermatozoa were dried in a water bath, pulverised, and treated with ether. During this process they yielded a not inconsiderable quantity of fat (i'Oo per cent.) of a yellowish colour and butter-like con- sistence. The spermatozoa, liberated from this fat, left, on being burnt, a black coal, which could not be made white by burning, and had an acid reaction, which was due to free phos- phoric acid. The total quantity of fixed constituents, in which, besides the phosphoric acid, Hme was recognised, amounted to 5*2 1 per cent. Another portion of the expressed semen was treated with a concentrated solution of nitre. It thereby became considerably tougher, more viscid, and filtered with difficulty. On adding water, a milk-like cloudiness was pro- duced in the filtered portion ; it was, how- ever, precipitated in the same manner as the simple watery extract by the infusion of galls. IS'itric acid caused a slight precipitate of al- bumen. A second series of experiments was insti- tuted on the semen from the testicles of a cock, in which, however, the spermatozoa were only scantily developed. The contents of the seminal tubes principally consisted of cells of developement, which could only be separated with difficulty from the tissues of the testicles. The filtered solution abounded in albumen, but contained, on the other hand, only a slight quantity of the matter (mucus), which was precipitable by acetic acid, and insoluble in excess of it. The residue on the filter (cells of deve- lopement and spermatozoa) was dissolved in solution of potash. The solution yielded a v;hite precipitate with acetic acid, which principally dissolved in excess of the acid (albuminous substance), whilst only a slight quantity remained undissolved (binoxyde of protein). An old rabbit, when in the period of rutting, was subjected to a third series of experiments. The moderately turgid testicle was cut into ])ieces, and the milky semen expressed. It consisted of spermatozoa and numerous epi- thelial cells. The reaction in the testicles was neutral, in the epididmis it was slightly alka- line. It could only be filtered imperfectly. The filtered solution was cloudy, and con- tained many spermatozoa. The presence of a slight quantity of albumen could be perceived on the application of boiling heat. The residue of spermatozoa left on the filter, and which were only imperfectly sepa- rated from the fluid, dissolved with tolerable ease in solution of potash, and were precipi- tated by acetic acid. A very slight quantity only dissolved in an excess oi"this acid. Only a slight cloudiness was produced in the acetic solution by ferro-cyomide of potassium. These different experiments yield the fol- lowing results : — 1. Tiie pure semen presents the appearance of a milky fluid, of a raucous consistence, and neutral reaction. A slight alkahne reaction was perceived only once. 2. The developed spermatozoa consist of binoxyde of protein, the same substance which Mulder has proved to be the principal constituent of the epithelia, as well as of the horny tissues in general.* 3. The spermatozoa contain about 4 per cent, of a butter-like fat, as well as phos- phorus in an unoxydized state, and about o per cent, of phosphate of hme. 4. The fluid part is a thin solution of mucus, which, in addition to the animal matter, contains chloride of sodium and small quan- tities of phosphate and sulphate of the alkahes. 5. The imperfectly developed spermatozoa are composed of an albuminous substance, the quantity of which diminishes in proportion to the progress of the morphological develope- ment. 6. The perfectlv developed semen contains no longer any albuminous compound. 7. The semen in fishes, birds, and mam- malia possesses, essentially, the same chemical composition. Such are the statements of Dr. Frerichs. The most important inference derivable from them appears to us to be the fact, that the spermatozoa, in their chemical composition, belong to the same category as the epithelial cells of the animal body. This fact removes every doubt respecting the nature of these formations, — every idea of their being inde- pendent animals. The spermatozoa are there- fore (as proved both by chemical analysis and by microscopical investigation) mere element- ary constituents of the male animal body, which, like their equivalents in the female ani- mal, the ova or contents of the ovaries, are distinguished from other histological elements b}- their having a different physiological pur- pose ; they have less influence on the indivi- dual in which they are produced, but are in- tended, when separated from that individual, to give rise to the formation of a new one.-j- * Tersucli einer AUgem. Phvsiolog. Chemie. § 532. 560. t In sopite of this functional difference we cannot help regarding spermatozoa and ova as constituents of the animal organization. Eeichert, who declares them to be organizations of quite a peculiar kind. SEMEN. 507 It is probably no false inference on our part, when we express the opinion that the de- veloped seminal elements present every where, and not merely in mammalia, birds, and fishes, the same composition. Indeed, we do not see any reason for assuming that this differs even in cases where the proper fluid is want- ing, and where it is only the spermatozoa which constitute the seminal mass. Phyuological office of the semen. — Al- though these results of chemical analysis appear very important for the knowledge of the nature and quality of the semen, yet they afford but little assistance to an in- vestigation respecting its modus oj)eran(li in the process of fecundation. Indeed, it w^ould almost seem that an answer to such an inquiry is farther oft' than ever, inasmuch as we now know that a peculiar substance of a specific quality exists, which we may indeed consider as the bearer of the fructifying prin- ciple,— but that an effective sj^ei-matme does not exist. The truth is, " the how'" of the fecundation is as far from our knowledge to- day as it was thousands of years ago ; this process is still enveloped in what we feel in- clined to consider " its sacred mystery." It would be different if we could prove that the spermatozoa really yielded the material found- ation for the body of the embryo ; that they penetrated into the ovum, and were deve- loped into the animal (which was the assump- tion of Leiiwenhock, Andri/, Gautier), or else, that they become metamorphosed into the central parts of the nervous system. However, we are now convinced that all these assumptions are without any found- ation. The import of the spermatozoa must be a very different one. But this is the very point of which we know nothing with any certainty. Leaving these views, which require no spe- cial refutation, to oblivion, the following two opinions on the nature of fecundation have taken a tolerable position in our physiology : — One of them consists in the opinion that the fructifying principle is lodged in the liquor seminis ; the other, that it is centred in the spermatozoa. Both, however, agree in this, that an actual material meeting, an immediate contact of semen and ova, is indispensable to effect fecundation. The doctrme of an Au7'a semincdis has long since, and most justly, been cast aside. It was natural that the former of these two opinions (viz. that which sought the essentials of fecundation in the fluid and its mode of action) should have found its advocates at a period when the existence of the spermatozoa was hardly known, or when, at all events, they were supposed to be mere parasitic animal forms. Indeed, this assumption is at first sight sup- wliich, in a certain degree, form a meclinm between animals and elementary parts of animals, seems en- tirely to forget that it is only the moi-phological condition, which can characterise a constituent of the body as such. The physiological comportment by itself ought not here to be taken into consideration at all. ported by arguments of a seductive nature. The liquor seminis, it was thought, comes into contact with the membranes of the ovum, and transudes them. It mixes itself with parts of the yolk, and enters with them into many chemical combinations, which fit them for a change in their capacity for organization, for the formation of cells, and for the developement of the embryo. This opinion did not, indeed, suffer at first from the recognition of the nor- mal nature of the spermatozoa. It was in- deed possible, as Burdach thought, to find in this very circumstance a prool^of the great organizability of the semen, of the ready mode of dispersing it, which such an operation upon the ovum would d jJriori require. Even up to the present day this hypothesis of the influence of the liquor seminis has not met with any direct refutation, although, as we shall see presently, it appears to us now, for many reasons, less admissible than it did to one of us formerly.* The presence of certain elementary structures in the seminal fluid cannot yet be connected with the part which they are intended to perform. It was indeed possible that the remarkable qualities of these structures had reference to the semi- nal fluid alone ; that they, as it were, formed isolated, free, ciliated epithelia, and that they were intended, by means of their movement, to bring the Hquor seminis into contact with the ovum ; or, as Valentin supposed, that the state of mixture of the semen, so readily dis- turbed, was preserved in its integrity through their motions. The circumstance of meeting now and then with motionless spermatozoa is not in itself sufficient to refute this con- jecture. For it might be said that in these cases such a provision might not be neces- sary, or that the object sought might be gained in another way, and that the spermatozoa merely existed as morphological equivalents of the moveable seminal fibres, w^ithout a similar physiological importance. The following fact, however, appears to us of more real importance, viz. that a hquor se- minis is positively not at all traceable in manv, and especially not in many of the lower, ani- mals, in worms, insects, &c. ; but that, on the contrary, the whole mass of the semen is formed by the spermatozoa alone. Another reason against the former assumption is this, that an action of the liquor seminis on the ova would be impossible in many cases, — where, for instance, the fecundation takes place in the water, and without any real act of copulation, the semen being ejected I'rora the male animals, and then lett to chance whether it comes in contact with the ova or not. Such facts speak too powerfully in favour of a specific purport of the spermatozoa in the act of impregnation to allow us to venture to say a word in support of the older assumption. In addition to this, it must be granted that the spermatozoa in the male individuals are, in a morphological point * R. Wagner, Physiologie, S. 38. fi08 SENSATION. of view, the representatives of the female generative products — the ova ; and that, as explained in the commencement of our article, we are enabled to pronounce the presence of a particularly large quantity of liquor seminis as a fact of subordinate significance in a his- tological point of view. Under these circumstances we do not hesi- tate any longer to coincide with KolUker and JSischoff* (the latter changed his opinion only recently) " that it is the spermatozoa which, by their contact, fructify the ovum." How this is done remains as much an enigma as the real essence, the remote cause, of eveiy thing else that is done. We are certainly able to watch growing life in its first commencement, to fathom the laws of the successive phases of its developement ; but the internal relation of all these processes is hidden from our percep- tion. It is possible, and, indeed, even probable, that the material constitution of the sperma- tozoa is somehow concerned in fecundation. Whether, however, as Bischoff supposes, the act of impregnation merely takes place accord- ing to the laws of the so-termed catalytic power, that a certain internal motion is trans- ferred from the spermatozoa to the molecules of the ova, which till then were in a dormant state, we do not venture to decide. At all events, the circumstance, that it is not the spermatozoa of every animal which are capable without any distinction of fructifying every egg, is sufficient in itself to prove that we have not here to deal with such very simple relations. It is an established fact, that only animals of the same species enter voluntarily into sexual connexion, and produce prolific young ones. The importance of this law, for the preservation of once created definite forms of life, is evident. Exceptions to this law are but rarely found, and generally are due to the interfer- ence of man. — Animals of a different species scarcely ever enter into sexual connexion in their natural state ; and, indeed, this act, when it does take place under such circum- stances, remains generally without any conse- quences. Fecundation only takes j^lace when the respective individuals approximate to- wards each other in point of genus, and even then the hybrids produced are generally un- fruitful. A fructifying act of procreation is known in them only in very rare cases, and that usually only when it takes place with one of the original stock, not among them- selves. This infertility or barrenness of the hy- brids, coincides in a very interesting manner with an imperfect developement of the sper- matozoa, a relation which we might certainly at once infer from the functional significance of these formations. In many cases there does not even seem to be any production of spermatozoa ; a fact proved by the older state- ments of Bonnet and Gleichen^ as well as by the more recent researches of Prevost and * Miiller's Archiv. 1847, S. 436. Dumas *, as well as of Hausmann f , with regard to the mule. One of us J found the same in the hybrids of goldfinches and canary-birds. In others, real spermatozoa develop themselves ; but they remain smaller than in the stock species (^V'' — -V'0» without the characteristic cork-screw spirals. The thicker end is generally oblong, and fre- quently curved at the point, or of an irregular club form. In addition to this, the sper- matozoa of the hybrids do not group together in bundles, owing perhaps to their being usually only small in number, even in the in- terior of the separate cysts. The microscopical examination of the semen in hybrids, the ca- pacity of propagation of which has been con- firmed, would be of importance. It is very probable that the spermatozoa in these cases have a regular developement, and their usual form. BiBLiOGRAPHT. — A. Leuwenhoek, Anatomia seu luteriora Eemm, Lugd. Batav. 1687 ; Arcana Xatm-fe, Delpliis, 1695 ; Epistolae Physiologicje, Delphis, 1719; Sur les Auimalciiles de fa Semence des Auimaux, Philos. Trans. 1672. LedermiUler, Physikalische Beobachtungen der Sameiithierchen, Nuremberg, 1756. Spallanzani, Xouvelles Ee- cherches sur les De'couv. jSlicroscop., Londres, 1769. Gleichen, Abliandlung iiber die Samen, und Infu- sionsthierchen, Nui-emberg, 1788. Prevost and Dumas, Annal. des Sc. Xat. torn. i. ii. Czermak, Beitrage zur Lehre von den Spermatozoen, Yienna, 1833. Treviranus, in Tiedemann's Zeitschrift, vol. ii. Von Siebold, in Miiller, Archiv, 1836, S. 232. ; 1837, S. 381. M Wagner, Fragmente zur Physio- logie der Zeugung ; Beitrage zur Geschichte der Zeugung und Entwickelung ; in den Abhandl. der Konigl. Baeierisch Acad., Munich, 1837. KoUiker, Beitrage zur Kenntniss^ der Geschlechtsverhaltnisse und Samenfliissigkeit wirbellosen Thiere, Berlin, 1841 ; Die Bildung der Samenfdden in Blaschen, Xurembg. 1846. (Rud. Wagiier and Rud. Leuckart.) SENSATION. — (Fr. Sensation; Germ. Emp^iidung.) — The improved state of our knowledge of the physiology of the ner- vous system makes it imperative that phy- siologists should adopt and adhere to a pre- cise definition of the term which forms the heading of this article. Perhaps the simplest definition of sensation which'can be given is the following ; namely the perception by the mind of a change wrought in the body. According to this definition, then, sensation involves, first, a bodily change, from some cause, whether in- herent or external ; and, secondly, a mental change, whereby the perception of the bodily change is accomplibhed. A hot substance is applied to the skin sufficient to burn ; a visible change is produced on the part to which the application has been made, shown by the in- creased redness of the cutaneous surface, and the nerves of the part are so irritated that pain must be felt if the perceiving power of * Annal. des Sciences Xat. i. p. 182. t Ueber der Mangel der Samenthierchen bei Haua- thierchen ; Hannover, 1844. X R. Wagner's Phvsiologv, § 20. Translation by Willis, § 12: SENSATION. 509 the mind be unimpaired. But unless the mind is conscious of the' irritation excited we cannot say that a sensation has taken place. The person on whom the injury is inflicted may be comatose, or in a profound sleep, or under the influence of intoxicating or anaesthetic agents, and consequently his perceptive powers are in abeyance. Never- theless, the same physical changes take place, whatever be the state of the mind, and all the physical phenomena, which may flow from or succeed to those which are capable of excit- ing sensation, may ensue upon them, and yet true sensation will not take place, unless the mind perceives and takes cognisance of the physical change induced. It must then be regarded as a cardinal point in reference to the acceptation of the term Sensation in Physiology, that an action of the mind is necessarily involved, that act being of the nature of a recognition or per- ception of the physical changes associated with the sensation. The true organ of sensation is the organ of the mind — the brain, and especially that part of the brain which constitutes the centre of sen- sation, and which extends into the spinal cord, forming the posterior horn of its grey matter. When an impression is made upon a nerve or nerves which communicate directly or indi- rectly with any part of this centre, a sensation is excited, provided the intracranial portion of it be in a normal state, and provided also the connection between the cranial and spinal portions be complete and uninterrupted. Sensations depend, as to their nature, on that of the excitant, and nerves are adapted to receive impressions from various agents, ponderable or imponderable. The mechanical qualities of bodies, heat, cold, electricity, light, sound, &c., are capable of exciting their ap- propriate sensations, which the mind soon learns to appreciate and distinguish. Sensa- tions thus distinguished receive the appella- tion of pleasurable or of painful, according as they are agreeable or the reverse. These sensations are infinitely varied in kind and in degree. It is impossible, d priori ^ to deter- mine how a pleasurable or a painful sensation may be excited. Nor will the experience of one person be always a guide for another, in- asmuch as a sensation which may be agree- able to one, may be painful or disagreeable to another. Physiologists distinguish sensation as com- mon and special : the former being that which is excited by ordinary mechanical or chemical stimuli ; the latter is excited by special sti- muli, and is exemplified in the special senses of vision, hearing, smell, taste, and touch. The nerve of vision does not, when irritated, communicate simply a feeling of pain or of pleasure ; its chief effect is to excite the sen- sation of a flash of light. When the electric stream passes through the retina, a sensation is caused similar to that which the sudden presentation of a luminous object would pro- duce. In like manner the mechanical or electrical stimulation of the other nerves of pure sense will create, not pain, but a feelmg closely allied to that which would be excited by the application of the stimulus proper to each. This is remarkably illustrated by the effects of mechanical or electrical stimulation of the nerve of hearing and of the nerve of taste. Mechanical impulses against the tym- panum occasion the sense of a dull sound, and the electric current developes a musical note. Galvanic excitation of the gustatory pa[)ill[E of the tongue causes a peculiar sour taste, and, as Dr. Baly has pointed out, the mechanical stimulation of them by a sharp tap with the fingers, occasions a taste some- times acid, sometimes saline. The nerves which minister to specia sensation, differ from the nerves of common sensation in no essential point of their ana- tomy, except in their mode of organisation at the periphery of the body. Each of them has, probably, likewise some peculiarity of connection with the brain : this is obvious as regards the olfactory and the optic nerves ; less so as regards the nerves of taste, touch, and hearing. The physiological peculiarity of these nerves is then, in all probability, due to their central and peripheral organisation ; and especially, perhaps, to the latter, which, doubt- less, renders them peculiarly susceptible of the influence of those delicate physical agencies to which each of them is exposed. The nerves and organs of special sensa- tion, especially those of touch, are so com- prehensive in their objects, that it would almost seem that little was left for the so- called nerves of common sensation. These latter nerves, nevertheless, serve many important objects ; they doubtless ex- cite in the mind many feelings, agreeable or disagreeable, of pain or of pleasure, or even feelings neutral as regards pain and pleasure, which could not be developed through the nerves of special sense. The consciousness of the integrity of our limbs and of the general framework of our bodies, is secured, in a great measure, through the instrumentality of these nerves. Injuries to various parts — disturbances in their nutrition, as inflammations, ulcera- tions, &c. — are made known to the mind by the painful sensation excited through these nerves. The sensibility of organs and textures — i. e. the degree to which affections of these parts are capable of inducing corresponding affections of the mind — depends upon the number of these nerves which are distributed to them — the degree of sensibility being in proportion to the number of the nerves. Hence these nerves of common sensation ex- ercise a conservative influence over the several textures and organs to which they are dis- tributed, and serve to afford warning of the approach or of the existence of danger. What some have called the muscular sense, i.e. the knowledge which we have of the state of our muscles, is generally attributed to these same nerves. As the sensibility of the muscles is doubtless due to these nerves, we may reasonably impute to them the faculty of informing the mind of the state and degree of contraction or relaxation of the muscles, and thus of contributing to that power of adjust- 610 SENSIBILITY. ment which is necessary to give precision to our muscular efforts. This sense comes greatly in aid of that of touch, and of those powers which we derive from the sense of touch. It admits of question whether this sense really requires the presence of true nerves of sensation in the muscles, and whether it may not be due to the reaction of the muscular force upon the proper muscular or motor nerves, through which, by reflection at the centre, the centre of sensation becomes affected. (See Nervous Systeji, Physiology of.) All nerves of sensation are excitors of mo- tion under certain circumstances, but especi- ally when they are organised at their periphe- ral distribution in a peculiar manner. Objective and subjective sensations. — In the ordinary mode of exciting sensations the pre- sence of an object is necessary. This object creates an impression on the peripheral parts of the sensitive nerves ; and the change caused by this impression, being duly propagated to the centre of sensation, is perceived by the mind. Thus is produced what some meta- physicians call an objective sensation. Such sensations are durable or transient, according to the force of the primary impres- sion. The mind may continue conscious of the sensation long after the exciting object shall have been withdrawn ; or the sensation having ceased, the mind may recall it, with more or less exactness, without the renewal of the original stimulus. This is one form of subjective sensation, in which a mental act can develope a sensation independently of any present object, but resembling a previously experienced objective sensation. Other forms of subjective sensations are caused by phy- sical changes in nerves themselves, or in those parts of the centres in which they are implanted. These changes are caused by alterations in the quantity, but more fre- quently in the quality, of the blood, the deficiency in some of its staminal principles, or the presence of some abnormal element in it, or by modifications in the nutrient actions of the nerves or nervous centres. Subjective sensations of this kind are those most com- monly met with. As examples of them we may refer to the motes or flashes of light occasioned by disturbed conditions of the retina, mechanically or otherwise ; or of the optic nerve ; or of those parts of the en- cephalon in which the optic nerve is im- planted ; tinnitus aurium, or singing in the ears, resulting from some analogous affections of the auditory nerve, or of the parts of the brain with which it is connected ; pains, or feelings of tingling or creeping in the limbs (formication). Reflex sensations. — The physical change developed in the production of an objective sensation at one part may give rise to what may be compared to a subjective sensa- tion in another and a remote part of the body. The irritation of a calculus in the bladiler will give rise to pain at the end of the penis, or to pains in the thighs. The ob- ject by which the irritation of the bladder is excited cannot exercise any direct influence on the nerves of the penis or of the thigh ; through the nerves of the bladder it excites that por- tion of the cord in which both the vesical nerves and the nerves of the penis and of the thigh are implanted, and thus the latter nerves are stimulated at their central ex- tremities through the influence of the peri- pheral stimulation ; in other words, the phy- sical changes excited in the first are reflected into the second. Sometimes distant and apparently wholly unconnected parts may be affected in this way. Thus irritation of the ovary will cause pain under the right or left mamma ; stimula- tion of the nipple, whether in male or female, gives rise to peculiar sensations referred to the genital organs ; ice suddenly introduced into the stomach will cause intense pain in either supra-orbital nerve ; acid in the sto- mach is apt to cause a similar pain, which may be very quickly relieved by the neutrahsation of the acid. Phenomena of this kind imply some closeness of connection between the nerves of the sympathising parts in the centre, probably by means of commissural fibres con- necting the respective points of implantation of the nerves with each other. For further remarks on the subject of this article see Nervous System, Physiology OF ; and the articles on the Senses, — Hearing, Smell, Taste, Touch, Vision. {R. B. Todd.) SENSIBILITY.— (Fr. SensibiUte ; Germ. Empjindlichkeit). — This term, like Sensa- tion, should be limited to signify the power which any organ or tissue of the body has, of causing changes inherent or excited in it to be perceived and recognised by the mind. The greater this power is in any tissue or organ, the more sensitive it is, — the greater the sensibilitj/ of the organ or tissue ; the less this power is, the less the sensibility of the organ, &c. Sensibility, like Sensation, involves the power of affecting the mind through the body; but as the mind, of its own mere motion, may excite the centre of sensation, so, by directing the attention specially to some particular tissue or organ, it may create a sensation which, will be referred to that part, and which, by frequent repetition, may assume the nature of pain. No doubt many instances of hys- terical pain are greatly aggravated by the mind being constantly directed to, and dwell- ing upon, tiie painful part. The term Sensibility is sometimes con- founded with Irritability, especially by Psycho- logical writers. Haller has, with great pre- cision, laid down the distinction between these two properties of tissues in the following words : — " Irritabilem partem corporis humani dico, quae ab externo aliquo contactu brevior fit ; valde irritabilem, quce a levi contactu, parum quae a valente demum causa in brevitatem cietur. Sentientem partem corporis humani SEROUS AND SYNOVIAL MEMBRANES. 511 appello cujus contractus animoe representatur ; et in animalibus brutis, de quorum anima non perinde liquet, eas partes sentientes dico, quibus irritatis animal doloris et incommodi signa ostendit ; insensilem contra partem quae usta, scissa, puncta, ad destructionem usque caesa, nullum doloris signum, convulsionem nullam, nullam in totius corporis situ muta- tionem excitat." * The sensibility of any part must be judged of by the readiness with which changes in it are perceived by the mind. In general, highly sentient parts, when stimulated, are capable of exciting movements in the muscles of neigh- bouring parts ; thus, stimulation of the sole of the foot excites motions in the whole lower extremity ; the stimulation of any other part of the leg, whilst it might excite movements, would not produce them to the same extent. The difference is due to the greater ; sensi- bility of the sole of the foot than of any other part of the integument of the lower extremity, and also to the peculiar connection of its sen- tient nerves with the papillary texture of the skin. The anatomical condition necessary for the developement of the greater or less sensibility in an organ or tissue, is the distribution in it of a greater or less number of sensitive nerves. Thus the anatomist can determine the degree to which this property is enjoyed by any tissue or organ by the amount of nervous supply which his research discloses ; and physiological experiments and surgical opera- tions furnish us with abundant evidence in confirmation of the, as it were, a jiriori sug- gestions of the anatomist. The sensibility of tissues is modified by disturbances of their nutrition, and thence in- flammatory affections tend to increased sensi- bility, and will even make parts sensitive which before were but slightly so. Thus the periosteum, which in health is but slightly sensitive, becomes, under the influence of in- flammation, exquisitely sensible. It is necessary to add that the word sensi- bihty is also used, as applied to nerves, to signify their power of evolving the nervous force. Excitability is a better word for this purpose, and ought to be generally used, to ensure a greater exactness in the applica- tion of physiological terms than has hitherto prevailed. (R. B. Todd.) SEROUS and SYNOVIAL MEM- BRANES.— {Membranes sereuseSy Fr.; Serose Haute, Serose Ueherzuge, Wasserhaute, Germ. Membranes synoviales, Fr. ; Synovial-KapselUy Synovial Haute,Germ.) — The names by which these structures are designated seem to have been originally derived from the appearances presented by fluids which are frequently found after death in the so-called cavities formed by their continuous interior surface. Thus, for instance, rejecting those cases * Haller, De Partibus corp humani seutientibus ct irritabilibus. — Op. Minora, t.i. p. 407. where marked symptoms of disease of these tissues precede death, the structures first named, where they offer any contents at all, present a fluid the colour and composition of which greatly approximate to that of the serum of the blood ; and thence the fluid so found names the tissues yielding it as the " serous " membranes : while the interior of the joints constantly affords a small quantity of a fluid, the viscid consistence of which, resembling that of the white of an egg, gives rise to the application of the name " synovial " membrane {(tw wov) to the tissue which immediately lines the articulation, and is presumed to yield it. But neither do these circumstances, nor that of their membranous form, by which the terms at the head of this article are completed, sufficiently express their most important characteristics. A serous membrane essen- tially consists of an endogenous cell-growth, covering a thin expansion of areolar tissue. The compound structure which results from this arrangement of these two tissues is thrown around the more moveable organs of the body, and also lines the cavities which they fill. By thus affording to these two opposed surfaces uniformity of texture and smoothness of surface, it greatly diminishes their mutual friction: or, in other words, facilitates their movements upon each other. It will, I think, be advantageous to defer for the present all consideration of the pos- sible or probable function of these membranes, as implying by that word an immediate organic operancy in virtue of their intimate structure; and to fix our attention chiefly on their mechanical use in reference to motion. In the living man, there are many processes which necessitate changes in the relations to space of the different parts of the body. The actions of locomotion, digestion, circu- lation, and respiration, for instance, all imply some degree of movement in the organs which are their immediate agents, often in the more important parts to which they immediately minister ; and, in many cases the protection of delicate organs appears to be partly ac- complished by an increase of their mobility upon neighbouring structures. The neces"^- sity of movement thus comes to be more or less participated in by almost all the tissues, organs, and segments of the body ; and as- suming, what is above stated, that it is the most obvious want for which serous mem- branes are destined to provide, we might naturally imagine, either that these structures would pervade as universally as this require- ment, or that those of similar import which should be substituted for them would suffi- ciently approximate in their nature and com- position to be referrible to the same class of tissues : a class, in which the degrees of re- semblance afforded by the different members should somewhat accord with the varying mechanical requirements of those difl^erent parts of the body, to the movements of which they were subservient. An appeal to facts abundantly confirms 512 SEROUS AND SYNOVIAL MEMBRANES. such an inference. Observation shows that in the human body a variety of structures exist, which are united by the characteristics not only of considerable analogy of office, but also of similarity of structure, almost complete identity of chemical composition, and intimacy of pathological relations. Adopting the possession of these common properties as a natural and safe basis of classification, we form a group in which are included all those tissues which serve to limit, define, or facilitate movement. The class of structures thus constituted was formerly termed " the Cellular System ; " but the cel- lularity which the name connotes, as it was never supposed to be predicable of all its members, so it is now known to be erro- neously used of that part of them to which it was originally applied ; and they have there- fore been preferably arranged under the head of Passive Organs of Locomotion." And if any should consider this term open to the lesser objection of specifying a general, but not essential fact, that of " Passive Organs of Movement " might be again substituted. On this view we may regard serous mem- branes as forming one of a group of tissues. A farther analysis of this group shows it to be composed of several members, separated from each other by differences, in which we may recognise a progressive, though some- what interrupted, series of gradations. These differences we shall now proceed rapidly to trace. Two important microscopical elements pervade all these structures, and will there- fore demand some attention. These are the white and yello w Jibrojis tissues. The white fibrous tissue (fig. 395. a) consists of bands or bundles of a very variable width, which, unless artificially stretched, take a sinuous or wavy course ; and, at distant in- tervals, include cell-nuclei in their substance. They are marked with striae, which take the direction of their length, and, by their mutual proximity, give a fibrous or fibrillated ap- Fig. 395. pearance to the whole mass. But these markings are not exactly parallel to the borders of the band ; and since the tissue, though easily divided longitudinally to almost any degree of minuteness, cannot be split up into uniform and definite fibrils of a diameter corresponding with the transverse width which intervenes between one of these striee and another; and since it is also swelled up into one shai)eless and semitransparent mass by the action of acetic acid ; it seems highly probable that they are limited to the surface of the bundle, or its immediate neighbourhood. At any rate, they do not sufficiently divide the mass to give it a filamentous constitution, or to render it " fibrous " in the true sense of the word. The yellow fibrous tissue (fig. 395. b) is contrasted with the preceding tbrm, not only by its colour, but equally by its minute struc- ture and properties. It consists of separate fibres, the size of which varies considerably in different parts, and, in a lesser degree, in any one specimen. They are exceedingly disposed to curl up, often assuming almost a spiral form ; and are rendered very distinctly visible by the dark margin which their great refracting power gives them. Their branchings are generally dichotomous, and the processes thus given off" are of a size which nearly equals that of the original stem ; and they may often be traced to their union with neighbouring ones, so as to form a kind of trellis- work. The first form exists alone in tendons, ligaments, and the stronger fasciae latag ; its inextensibility and strength admirably adapting it to the use of mere passive resistance to an external force. The second is highly elastic, whence it is often termed " the elastic tissue :" it is chiefly found where, along with a certain amount of yielding, is also required a complete restoration of the previous state without any further expenditure of muscular force, the long duration of an action often rendering it advantageous to avoid the fatigue which the constant exercise ofvoHtion and muscle would imply. And as these conditions are much rarer than the simply mechanical wants which the preceding form is destined to supply, so also is the tissue which fulfils them, being found separately in but a few parts of the body; viz. in the ligamenta subflava, and in certain portions of the vocal and respiratory apparatus. Here it is in sparing quantity ; but in the vast ligamentum nuchag, whicii suspends the ponderous heads of the horned graminivora, the uses of the tissue are ex- eniplified in a very striking manner. Chemically, they are distinguished by the white fibrous tissue containing much gelatine, or rather yielding it by boiling ; while, from the yellow, none can be obtained. They are both little disposed to putrefaction, and retain their peculiar physical properties almost un- impaired by time.* * In an Egj^tian muramy, T lately found these tissues (after moistening) displacing as perfect a structure as a specimen of yesterday cculd have done. SEROUS AND SYNOVIAL MEMBRANES. 513 A mixture of these two elements consti- tutes the areolar tissue, which enters so largely into the formation of almost all the organs. The bands of the one and the fibres of the other are closely interwoven, although with- out mutual continuity ; each giving ctf'branches which again unite with the other neighbouring subdivisions of the same kind, so as to form a compHcated interlacement of the two net- works. This arrangement results in an innu- merable series of meshes, which everywhere communicate with those in their immediate proximity, and the size and shape of which varies within very wide limits. And these limits are frequently still further extended, since the separation of some of these micro- scopic meshes, and the approximation and condensation of others, gives rise to the for- mation of a secondary net-work, which is visible to the naked eye, and which, though still open in every direction, possesses, espe- cially in inflated and dried preparations, an appearance sufficiently resembling that of cells to remind one of the name formerly applied to this structure, which was called, as if KUT iloxvv, " the cellular tissue." The proportion in which these two consti- tuents are mixed varies greatly in the areolar tissue of different parts of the body ; the pre- ponderance of one over the other following that of the conditions which were previously stated to regulate their separate presence. Thus, the likelihood of its frequent and great distention is often a requisition of increased elasticity, and is then accompanied by an increased proportion of the yellow element. Similarly, the amount of this compound structure present in different parts appears to depend mainly on its uses. Its offices of uniting the different textures, and of convoying the vessels and nerves, render it necessary that more or less of the tissue should always be present on the exterior of an organ ; and the same circumstances would lead us to expect a slight penetration of its surface. In the interior of organs, however, its absence is by no means infrequent, and is very significant of its use. Thus, the minute elements of the osseous tissue are physically insusceptible of movement; the permissive and facilitating structure becomes unnecessary and impossible ; and is therefore absent. The highly delicate nervous pulp not only pos- sesses no inherent mobility, but, by the ex- treme delicacy of its structure, offers a physiological obstacle to movement of equal importance with the preceding, and is accom- panied by a similar absence of the tissue. The intimate mutual connection of the mus- cular fibres of the heart, and their association in a common and nearly simultaneous move- ment, is associated with a like deprivation of this interstitial structure. The same absence at once of the necessity and of the tissue is seen in glandular organs, the situation of which shields them from injurious external force, as appears to be the case with the liver. But where opposite circumstances obtain, VOL. IV. where extent and variety of movement imply considerable mobility of the neighbouring muscles of a limb, or situation exposes an organ to external violence, a large quantity envelopes these different textures, penetrating between the diflTerent muscles and isolating their several fibres, or breaking up the gland into numerous subdivisions, moveable on each other : of this latter, the mamma is a familiar instance. A similar relation might be traced in the wider circumstances of its application. Not only does it form a web of union to the whole body, but it also presents a special layer of considerable thickness, which invests its sur- face, and partitions which isolate its muscles. And something of a corresponding minimum is found in those animals whose locomotive movements are few and simple, or whose situation and habits little expose them to external violence. So that a rbugh gradation might be traced through fishes, cetaceans, and reptiles, to mammals ; in which last class man stands pre-eminent in the number and complexity of his voluntary motions, and in the remarkable amount of this subservient tissue. An increase in the freedom of movement of contiguous parts is associated with an increased laxity of this web, the meshes of which become both longer and wider, so as to be more capable of stretching. They thus allow a greater amount of separation to take place between the parts which are attached to the extremities of their irregular net- work. BuRSTE. — Here and there throughout the body, where integument or tendon glides over a bony prominence, a further provision occurs, as the development of distinct cavities, which are lined by a smooth shining surface. By dissecting their parietes from the sur- rounding looser cellular tissue, they may be artificially exhibited as a membrane ; and hence these sacs, closed at all points of their circumference, have received the appellation of burs-D IXTESTIXAL CanAL." physical process of transudation : a process which is present everywhere in the body, but is favoured by the thin parietes of these struc- tures, while their position prevents the re- moval of the fluid by evaporation. But the fluid yielded by this supposed process appears to be chiefly aqueous ; and the question therefore readily suggests itself, whether any mere transudation could filter off the dissolved constituents from a perfect so- lution, such as the liquor sanguinis is known to be ; and whether the elective affinities of the tissue itself may not constitute the main agents of the process, by retaining certain materials, and allowing others to obey this physical law. Valentin * mentions some ex- periments in which dried serous membrane was used as the filter, and albumen, so far suspended in water as to constitute a homo- geneous fluid under the microscope, was passed through it. The result was, that it retained a thicker portion, while only a thinner or more dilute part passed through. But saline solutions transuded entire, and perhaps the doubtful state of solution of the organic con- stituent will not permit much reliance to be placed on these experiments. In connection with this subject, Mr. Paget -j- has pointed out that the different serous membranes seem to effect this " filtration " with different de- grees of fineness. And, possibly, the dimi- nution of albumen noticed in the liquor amnii of advanced pregnancy may be ascribed to a similar subtraction from this fluid by the serous meirbrane in the cavity of which it is situated. The share which the cells as such take in this process can scarceh' be conjec- tured ; but that their disposition in such a form is not absolr.tely essential to the fluid, is shown by its occurrence in the areolar tissue, where such a stratum is absent. And while we know next to nothing of the process itself, and have no name by which it may be exclu- sively indicated, it is important to recollect that the words used above, " elective afSnity," " subtraction," " filtration," are probably alike inaccurate ; that the first seems to imply chemical combination, the second represents the subtracted materials as too passive, the third is the nam.e of a physical process by which solid objects are left behind after the removal, by capillary attraction, of the fluid in which they were suspended. The pro- cesses to which it seems most analogous, and to which it may best be compared, are those curious varieties of heterogeneous adhesion existing between bodies of different cohesive forms, of which the action of charcoal or platinum upon certain gases are familiar in- stances The period of duration of the cell-growth, and the manner of its renewal, can only be conjectured. But from the constant absence of shed epithelium from the interior of the membrane, and the uniform shape and mutual * Lehrbuch der Plivsiolo2:ie des Menschen, Band 1., S. 6nl. t Keport on the Progress of Human Anatomy (Brit, and For. Keview, year 1843-4, p. 10.) SEROUS AND SYNOVIAL MEMBRANES. 520 adhesion of the cells, one might imagine that the stratum ordinarily lasts a considerable period without experiencing any desquamation or substitution of new cells. And although the ease with which a layer of cells is stripped off by slight force might at first sight seem opposed to such a notion of their durability, yet it is tolerably certain that the mechanical relations of the cells are so adjusted as to allow the free gUding movements of their moist, smooth surface with perfect impunity. While, on the other hand, where the presence of the tissue seems to fulfil its main object, a mechanical one, and where the flattened epi' thelium does not include the elements of a secretion in any quantity, and consequently would hardly fulfil any secretory purpose by its occasional or exceptional separation ; to what purpose should it be ever shed at all ? The serous membrane exhibits one layer of solid cells, all of which are related by one (the nucleated) surface with the neighbouring vascular supplies, while they present their o[)- posite surface to receive a slight friction ; and it does seem possible that the effete ma- terials may be removed, the losses of friction made up, and, in a word, the gradual exchange which constitutes the nutrition of a tissue accomplished, without the disruption of the old cell and the substitution of an entire fresh one. The cell-form does not necessarily imply evanescence, and the centre of attraction which it constitutes can hardly be supposed unfitted for the processes of ordinary nutri- tion, because it sometimes collects materials which imply its destruction, or is thrust away from the sources of nourishment by its fellow vesicles. And if it should be asked, " Why is the serous membrane constituted of cells, if the ordinary form of nutrition would suffice?" it might be pointed out that, although the form of nutrition be the same, its pace may and probably does attain a greater rapidity in cells than in the more permanent textures, and that by their instrumentality the rubbing surfaces are everywhere separated by an ap- preciable interval from the delicate capillaries, a condition that could scarcely obtain in areolar or ligamentous tissue, however it were disposed ; and that in addition to this, cells ofl^er the mechanical advantage of forming a smooth tesselated pavement, while they possess the physiological merit of readily repairing the accidents to which this tissue seems compa- ratively more liable than others. The synovial membranes seem to differ from the serous membranes in most of these respects. The cells which cover the general surface of the membrane are more spherical, less uniform in size, and less accurately tes- selated ; while on the highly vascular fringes, the large, globular, and distended epithelia, with their plentiful blastema, strengthen the indications of active secretion thus afforded. The presence of synovia in considerable quan- tity, and the recognition of the ordinary se- cretory process, by the detection in it of relics of celis, chiefly nuclei, form another ground of distinction. This secretion of viscid fluid VOL. IV. appears to be indirectly referrible to the greater pressure exerted on these surfaces, and the consequent necessity of a further protection against friction ; while it is no doubt immedi- ately the result of the separation of this active cell-growth, alone, or accompanied by fluid derived from the vessels. The bursting of the distended and delicate cell is probably the agent of the separation, and may be due solely to a distention beyond the [)hysical power of resistance which its wall possesses. The resistance of the cells on the general or capsular part of the synovial surface, and the irregular and isolated manner in whicii force detaches them, have been previously noticed, and contrasted with the facility of removing the whole layer of serous cells. They seem to denote, not only a mechanical adaptation to greater friction, but perhaps a corresponding independency of the cells, which possibly form a continuous and active growth, scarcely any two portions of which are exactly of the same age. And not only is the secretory activity of these membranes much greater, but there is every reason to suppose their absorptive fiinc- tions are still more increased. Assuming, from the preceding appearances of active cell- growth, that a greater quantity of fluid is se- creted by them into the cavity of the joint than the amount of serum which finds its way into the interior of the serous membranes; — since only a tolerably uniform and small quan- tity is discovered to be present there, — it will follow, that the rapidity of its removal has corresponded with that of its introduction : and as this removal cannot be attributed to any other cause than that of absorption, we must therefore regard its increase as parallel with the increase of secretion. But there is another circumstance which renders it likely that the former of these two processes is even disproportionally greater. However carefully the surfaces of diarthrodial cartilage may be lubricated by li^e synovial fluid, a very slight knowledge uf mechanics would inform us, that some friction of these must of necessity obtain ; and that from the conditions of its density, homogeneous nature, &c., it is probable that the amount of this is, though diminished, yet by no means incon- siderable. So also, from the structure of this substance, it is physiologically probable that its tissue grows towards this surface, and that the arrival of any one particular portion at this point is, mediately or immediately, the cause of the termination of its existence. While the anatomy of this free edge abun- dantly confirms the fact of such an attrition: vertical sections show an irregular border, from which some cells are seen slightly projecting, while others appear (as mJigAO'Z) ground down to its level. Whatever be the amount of cartilage which is thus rubbed off" and set free in the cavity of the articulation, or whatever may be the cohesive form which it assumes, the thick and solid cartilaginous lamina wliich is interposed between this " debris " and the JM M 530 SEROUS AND SYNOVIAL MEMBRANES. vessels at the osseous suruice (the vessels to which in the first instance the formation of the tissue was due) seems to constitute an effectual barrier to the performance of its absorption by them. And since the process no doubt occurs, the only remaining vascular surface, or that of the synovial membrane, is clearly indicated as the agent by which it is effected. Hence, the synovial membrane possesses, so to speak, a double absorptive function : one, which is essentially its own, counter- balancing the active progress of secretion, of which it is the seat ; another, which is, as it were, delegated to it by the cartilage, and is the result of the physical incapacity of the latter tissue. And in a sketch of the morbid anatomy of these structures which occupies the subse- quent part of this article, it will be seen that the mutual dependence thus supposed to exist between the articular cartilage and synovial membrane in health, finds, in all probabihty, a close parallel in some forms of disease. The chief difference noticeable here is, that the preliminary breaking up of structure which appears to be chiefly physi- cal or attritional in the normal cartilage, is a vital process which is inherent to the diseased texture. The subcutaneous and subtendinous bursce present a similar fluid, which is usually in much smaller quantity. They seem, in most of the preceding respects, placed midway be- tween the serous and synonal membranes ; but many of the preceding remarks, mutatis mutandis, are applicable to them. The close resemblance of the choroid jjli'xus to the synovial fringes was pointed out in speaking of the former structure : but it is obviously almost impossible to conjec- ture a similar mechanical import of its secre- tion ; nor, indeed, have we any reason for asserting the separate existence of a fluid secreted by it. In respect of their internal situation, all the preceding tissues resemble that recondite class of structures, the glands without ducts ; and their similarity of form has also a physio- logical parallel; — viz. that all their consti- tuents are returned into the b'ood, either unchanged in their composition, or elabo- rated, or effete. They differ from them, however, both in the greater perfection or maturity of their cell- form, and in the lesser activity of their secerning power. In the degree, and perha|)s in the nature, of this resemblance, some distinctions may be drawn. Thus, the serous membranes, in the possession of a solid attenuated epithelium, and in the probable absence of a secretion, are at the lowest or most distant extremity of the scale ; raised very little above areolar tissue. The si/novial membrane, with its much more active cell-growth, and its fluid secretion, comes somewhat nearer; albeit, the secretion seems mainly developed in answer to the mechanical requirement of a lubricating fluid. Still, the possibility of a less physical function of both these tissues must not be lost sight of. In the choroid j^lexus, the approximation is made yet more close by the negation of this mechanical import; and we are left in complete doubt, whether it is a provision for quantitative or qualitative fluc- tuations in the blood which supplies it ; whether, in either of these cases, the cell- growth operates a chemical change or elabo- ration on the materials submitted to its action ; or, finally, whether it returns these to the circulation, or surrenders them at once to the neighbouring nervous tissues. Morbid Anatojiy of Serous and Sy- novial ^Membranes. — The following sketch of the diseased appearances of these tissues is necessarily limited to their more general features. At present, it is scarcely pos^^ible to discriminate between the very analogous pa- thological conditions of the two classes of serous and synovial membrane ; although it is probable that an advance of knowledge will at no distant date enable us to do so. And even where the distinctions of appearances are sufficiently palpable, our ignorance of their general nature allows few inferences to be drawn from these varieties. Thus, the remarkable immunity from me- chanically-produced effusions which the syno- vial membranes enjoy is little understood, although one may perhaps doubt whether it is quite so complete as it is generally sup- posed to be. The only conjecture that seems at all probable is, that the nature and activity of the cell-grow th which covers their surface may have some relation to the diffi- culty with which such fluids transude. So, also, the comparative infrequency of adhesion in their inflammations is, at present, a vague fact, the cause of which is unknown; — it may either be referred to an explanation similar to the preceding, or may, as Profes- sors Todd and Bowman suggest*, depend upon the presence of a viscid secretion in their interior. Sei'ous or dropsical effusions. — One of the most frequent of the morbid appearances seen in these tissues is the presence of a serum-like fluid in their cavity. It occurs in a very large number o: deaths from various diseases. In most instances, however, the serous membrane only shares in a dropsy which is common to other structures, and especially affects the areolar tissue. Thus, for instance, where death has resulted from some mediate or immediate obstruction to the passage of blood through the right cavi- ties of the heart, and has been preceded for some time by general anasarca, it is usual to find a considerable quantity of fluid occupy- ing the pleura, peritoneum, and other serous membranes. In other diseases, as in cirrhosis, the serous effusion is not only a more direct result of a greater venous obstruction, but it also assumes a higher import than in the previous instance, and becomes both of earher occurrence in the history of the dis- * Physiological Anatomy and Physiology of Man, vol. i. p. 131. SEROUS AND SYNOVIAL MEMBRANES. 531 order, and of weightier influence upon its termination. Here, an accompanying dropsy of the areolar tissue is less frequent and prominent, but it still generally follows at a certain stage of duration and intensity : it is usually ascribed to the pressure of the dis- tended belly acting upon the vena cava, and producing a secondary dropsy from the branches of the systemic circulation which join that vein. In another class of cases, the serous effu- sion is still common to the areolar tissue and the serous membranes, but it arises from a different cause ; one which is no longer a mechanical impediment, but a chemical altera- tion. The dropsy of chlorosis is a good example of this species of effusion, and to it may probably be also referred that seen in the latter stage of phthisis and other ex- hausting disorders. Analysis shows, that in these ancemicE the blood is rendered much poorer by the loss of a considerable propor- tion of its albumen, and the serum of the thus diluted fluid possesses a greater tendency to transude the membranous walls of the vessels, and pervades the surrounding struc- tures in an undue quantity. Below a certain percentage of albumen, Andral afhrms the occurrence of dropsy to be tolerably constant. To these two classes may be added a third, in which serum is found in these structures without any sign or symptom of its presence having been detected during life. These eases are so numerous, that, even after sub- tracting a considerable number as possibly due to neglect or difficulty of recognition during life, a large number still remain, in which the effusion may be fairly presumed to have taken place after death. And in many instances, they are not only affected by gravi- tation, but, like the very analogous condition of the areolar tissue, their occurrence seems to be favoured by it. Yet, as such appear- ances are absent from a large majority of post-mortem inspections, it will follow, that the effusion of this fluid is to be ascribed, at least in part, to some conditions other than mere gravity. These are probably similar to the circumstances which conduce to the pro- duction of the preceding class of effusions, a deficiency of the albuminous constituent in the blood, or, with lesser hkelihood, the condition of the walls of the containing vessels themselves. They thus appear to be due to both a mechanical and chemical affec- tion of the blood, and so seem to offer an union of the two causes to which the pre- ceding classes have been severally ascribed. Many of the serous fluids which are found in the ventricles of the brain and beneath its arachnoid membrane, offer sufficient distinc- tions in their nature and causes to merit recognition as a separate variety. They are alike independent of physical obstruction of the vessels, or of a qualitative alteration of their contents ; while their quantity, which is frequently a considerable one, and the corre- sponding diminution of the size of the brain, together clearly indicate that they are not due to mere post-mortem phenomena. But while, on the one hand, they are unattended by these, the ordinary causes of such effii- sions, and are devoid of all symptoms which would indicate them as in themselves mor- bid ; so, on the other, they are not present in the healthy subject. Hence we may deduce, first, that they are related to some abnormal condition ; and secondly, that this relation is not an immediate one. This may be confirmed by considering that the organ bathed by these fluids is one which, from its physical and physiological properties, its soft consistence and important functions, is both peculiarly susceptible of disturbance from pressure, and ready to give signs of such disturbance ; so that the absence of these indications betokens a nicety of adaptation of the fluid to the cranium and its contents which is hardly to be explained in any other way than by sup- posing that this adaptation is itself the ob- ject which the presence of the serum fidfils,. or that the want of it is the condition which necessitates the effusion, if indeed it does not more immediately give rise to it. In the cerebro-spinal fluid itself, we are pre- sented with a more normal counterpart of this scarcely morbid effusion ; since a fluid of similar constitution, in lesser quantity, is here a constant phenomenon. In tlie loose and vascular areolar tissue between, the arachnoid and the spinal cord, this perpetual dropsy is the natural condition of the part ; and is perhaps due to the greater mobility enjoyed by the vertebral colunui where it surrounds these parts of the nervous centre, a freedom of movement which requires that they, in their turn, should be more carefully protected from external violence. Fliysical and chemical properties. — The appearances of the fluid found in the cir- cumstances above mentioned are tolerably uniform, and the few variations that occur are chiefly of an accidental nature. It is usually a limpid, colourless, and transparent fluid, of a faintly alkaline reaction ; and, in a state of purity, it offers no trace of organiz- ation, either to the naked eye or the micro- scope. In its consistence, however, it is susceptible of great differences. It varies from the hmpidity of water to the viscidity of synovia ; and when containing very much albumen, is sometimes even thicker and more tenacious than this liquid. Its colour is very frequently and greatly affected by admixture with blood, bile, and other matters; or by the partial precipitation of its albumen ; or, more rarely, by the solidification or crystal- lisation of fatty constituents. Many of these causes also affect its transparency, giving it more or less opacity, as well as colour. Its alkalinity is less liable to variation ; but occa- sionally it is neutral, and very rarely acid. Its unorganized character is only interfered with by accidental impurities similar to those above noticed. The chemical composition of these fluids is much more variable; indeed it is very pro- bable that scarcely any two of them are 532 SEROUS AND SYNOVIAL MEMBRANES. exactly alike in this respect. The following table exhibits four analyses, contrasted with that of the serum of the blood : — Serum of Blood. Phthi. sis.* Asci- tes .f Ascites. Ascites. Water - 905 988 988 956 704 Albumen 78 3 0-9 29 290 Extractive - 4-2 9 2 Fat - 3-8 }• 10 7 Salts - 9 8 4 1000 1000 998-9 1009 1000 The difference in the amount of albumen which these analyses exhibit is very striking ; and the large quantity present in the latter is especially remarkable as offering nearly four times the quantity which is present in the serum of the blood. The anomaly of an unorganized liquid, derived from the blood, possessing more of this important constituent than the parent fluid, has been attributed by Vogel to a reabsorption of the watery parts subsequently to the effusion. The varying methods of analysing these fluids leave less room to remark fjuantitative differences of their other constituents. The quantity of salts seems, however, pretty constant ; al- though the following analysis J exhibits a singular increase in one of the most common saline ingredients. It was taken from the dropsical belly of a woman aged 40, and the urine is stated to have contained about 6 parts in the 1000 of the same salt. Water 950 Extractive, with traces of albumen - 5-97 Fat -84 Almost pure chloride of sodium - 44 1000-81 The small number of analyses hitherto made, and the incompleteness of the patho- logical notice with which they are usually accompanied, render it at present too early to arrange the composition of these fluids in any real connexion with the various morbid states which have regulated their production. But the possible cause of an excessive pre- ponderance of albumen has been already alluded to, and on the whole it seems likely that the cases where this substance is of a less remarkable, but still a considerable amount, belong chiefly to the category of dropsy from mechanical obstruction ; while the dropsies of anaemiae, post-mortem trans- udation, and the like, seem to be characterised by the possession of a very small quantity of albumen : thus the second analysis in the table exhibits only three parts in the thousand ; * Reduced from an analysis by Karl Frua. Heller's Archiv., 1845, S. 363. The fluid was found in the abdominal cavity. f An analysis by Vogel, from whose " Patholo- gie " the remaining analyses by von Bibi-a, Dublauc, and Lecanu, are quoted at second-hand. X Heller's Archiv fur Phys. und Path. Chemie, 1844, S. 47. and two or three others are given by the same author, which have a very similar com- position. In the serous fluids of the cerebral ventricles, the quantity of albumen appears still smaller, as is exemplified in the following analysis by Berzelius.* Water 988-3 Chloride of sodium and potassium - 7-09 Albumen - - - - - 1-66 Lactate of soda, with alcohol extract - 2-32 Soda -28 Extractive, with traces of phosphates -35 1000-00 In respect of their diminished quantity of albumen, it is difficult to avoid noticing their approximation to the characters of the cerebro- spinal fluid, the vitreous humor, and other healthy effusions. The question that next suggests itself is, *' What relations do these fluids bear to the serous membranes?" From a comparison of the analyses quoted above, it is sufficiently obvious that amid multiform phases of com- position all these fluids preserve a close re- semblance to the serum of the blood ; a feature which sufficiently testifies to their origin and import, and which refers their production to the conditions of the blood, and their consi- deration to the pathology of this fluid, rather than to the serous membranes in contact with which they are found. And the bearing of this evidence is corroborated by several other facts. In a vast majority of cases, as above mentioned, their occurrence may be directly traced to blood disorders ; either a qualitative affection of this fluid, or a me- chanical distention of its containing vessels, — a mutual dependence which tends still more to allot them to the blood rather than to the serous membranes. Again, instead of their presenting the cellular form, in which the ele- ments of secretion, morbid as well as healthy, are usually involved, and which they might be expected to assume were they essentially the product of the cell-growing membrane, they are devoid of all appearances of such organ- ization. While in place of being peculiar to these membranes, it is found that an iden- tical effusion obtains in the areolar tissue; a structure which is alike destitute of their membranous form and epithelial covering. Inflammatory or fibruious effusions. — A large number of the fluids which are found eflfused in the interior of the serous mem- branes offer characters which essentially dis- tinguish them from the dropsical effusions ivbove described. The first and most pro- minent differences are those presented by their appearance and chemical comjJosition. In addition to the albumen and salts which form the main constituents of the serous effusions, they also offer a greater or lesser quantity of fibrine ; and as this substance retains its or- dinary power of spontaneous coagulation, its presence is readily recognized by the eye. * Simon's Chemie, Band ii. § 581. The case is mentioned as " Hydi-ocephalus." SEROUS AND SYNOVIAL MEMBRANES. 533 To these physical differences accede equally important patliological grounds of discrimina- tion. The effusion of the fibrinous fluid is usually attended by more or fewer of those symptoms, the aggregate of which is known by the name of injlammation ; and in the few instances where these external indications are absent, the presence of the fluid is itself con- sidered sufficient evidence of the previous oc- currence of the inflammatory process ; while the mechanical causes, which often appear mediately or immediately to determine the occurrence of the simply albuminous effusion, seem to have no influence in the production of these phenomena. Lastly, the fibrinous effusion is distinguished by this important quality, that it is susceptible of organization, or capable of an apparent conversion into tissues, the structure of which closely approxi- mates to that of some one or other of the normal and permanent textures of the human body. The class of effusions characterised by the possession of the common properties of fibri- nous composition, inflammatory origin, and susceptibihty of organization, is a very large one, and includes a great variety of fluids. The extremes of these numerous gradations offer some contrast ; in one the symptoms of inflammation are well marked, and the effusion chiefly consists of matters which are plastic ^ Le. which pass rapidly from a fluid state, through that of an uniform pasty mass, into a solid form ; and which for the most part ex- perience a rapid and CG>mplete organization, being converted either inio pus or into some more permanent structure. In the other sub- division, the symptoms of inflammation are usually less marked, the fluid contains less fibrine, is less susceptible of organization, and not only remains chiefly fluid, but, in a large number of instances, does not deposit any part of its contents in a solid form until sub- sequently to its removal from the living body, or after the death of the patient. In the earliest stage of inflammation, and before eflTusion has yet occurred, the morbid appearances of the serous membranes are limited to an injection, or active congestion of their vessels. Most of these, it will be recol- lected, are arranged as a flattened plexus in the areolar tissue which forms so large a part of the membrane ; and the injection of this plexus, at first in isolated points, and after- wards in larger patches, gives to these parrs of the free surface a heightened red colour, which is clearly visible through the thin and almost transparent layer of cells, alone inter- vening between the capillaries and the interior of the membrane. But although a superficial, patchy, and well-marked redness, dependent on congestion of the minutest vessels, con- stitutes a tolerable presumption of the presence of inflammation, yet such a state can be so closely imitated by conditions which are not inflannnatory, — such as a merely passive ve- nous congestion, due to position of the body, mode of death, and a variety of other causes, — as to be, in a majority of cases, of little value as evidence of this process. And even in instances where the symptoms during life have rendered the existence of inflammation probable, an examination after death has often detected no such appearance ; whence it would seem that this vascularity is capable of dis- turbance or removal, either during the phe- nomena of death, or after that event has hap- pened. And it is also to be noted, that the different serous structures seem liable to this appearance in a very different degree : some, as the arachnoid, scarcely ever presenting any trace of such a suffusion ; while in others, as the pleura, it is much more frequent. So that, on the whole, it may be stated that neither does its presence affirm, nor its ab- sence deny, the occurrence of inflammation j still less, where present, is its amount to be considered any measure of the intensity of ths process. An alteration in the texture of the mem-' brane itself is probably immediately subsequent to this injection in the order of time, and is generally seen in connection with it. Ita surface, instead of the smooth and shining appearance which it ordinarily possesses, be* comes dull and dim, while it is dry and almost rough to the touch ; and at the same time the thin and transparent expanse of its texture acquires a milky opacity, and an increased thicknesSy which in the more delicate serous membranes is especially well marked. The former of these appearances probably indicates some affection of the epithelium, which clothes the free surface of the membrane ;. but the latter is due to the commencement of effusion. This process begins where we should natu- rally expect it, viz. in the immediate neigh- bourhood of the vessels, or in the subserous and neighbouring areolar tissue in which they ramify ; and by the filling and distention of the meshes of this net-work, it gradually com- municates its own appearances to the sur- rounding tissue generally. The next stage is constituted by the ap- pearance of the products of inflammation on the inner or free surface of the membrane, or the effusion of a plastic fluid into their cavity. This effusion is at first a clear transparent fluid, of a tolerably hmpid consistence. It is true that we are rarely able to verify this transparency in the exsudation of the larger serous membranes ; but the condition of the blood plasma from which it is derived, and the similar appearance which is visible in the case of fluid effused into the inflamed anterior chamber of the eye, together leave no doubt of the fact. In a space of time which is a very short one, this uniformly fluid state usually gives place to a greater or less opacity and solidi- fication; and in this, the earliest stage in which the effusion is generally recognized, it offers the appearance of a milky semifluid substance, which either forms the whole of its mass, or is mixed with a variable quantity of serum, from which it has thus already begun to separate. The covijwsition of this effused fluid exhibits M M 3 SEROUS AND SYNOVIAL MEMBRANES. jjreat variety in different cases. The follow- ing table is an average of five analyses by Quevenne, Scherer, and Vogel, which is com- pared with the liquor sanguinis of healthy blood, as analysed by Lecanu. This im- portant comparative method of regarding these fluids is due to Vogel, in whose valu- able work these analyses are given at length. Liquor San- Fibrinous Ef- guinis. fusion. Water - - - 90G 934-936 Fibrine - - - 3-4 -984 Albumen - - 77 51-88 Extractive - - 3 ") Fat - - - 3 V 12-2 Salts - - - 8_ J The compositiou of 1000-4 1000- A comparison of the composition of this fluid with that of the serous effusion which was previously described, not only exhibits the addition of a new constituent, fibrine, but it shows the quantit}' of albumen to be in- creased in an important degree ; it being, on the average, nearly trebled. Contrasting it with the normal liquor sanguinis, it is seen to possess a considerable proportion of its albu- men and fibrine, although less than this fluid itself contains. And it is important to notice, that the former of these two constituents is not only present in larger quantity than the latter, as might be expected from its very different amount in the parent fluid, but in a much greater proportion of its respective quantity, i. e. that only two- sevenths of the fibrine of the liquor sanguinis appears in the inflammatory exsudation, while five-sevenths of its albumen is present. And in all proba- bility, were the diseased liquor sanguinis of the same subjects the object of comparison, its increased quantity of fibrine would render the disproportionately small transudation of this constituent a still smaller one. Although the number of analyses from which the average is taken will allow little stress to be laid upon these facts, yet they have seemed to deserve especial notice, as having some bearing upon a question which is of the greatest importance to pathology, and which cannot yet be con- sidered as settled, viz. *' What is the relation of fibrine to the process of organization ?" The further progress of the exsudation arranges the plastic or fibrinous constituent as a more complete coagulum, which is in contact with the inner surface of the serous membrane. The colour of this portion of the exsudation is yellowish, or sometimes reddish from mixed blood ; its thickness varies from that of a scarcely perceptible deposit to one of half an inch or more in thickness. The uniformity with which it covers the interior of the membrane is also subject to great differences ; sometimes it is arranged as a stratum of tolerably equal thickness over the whole or a greater part of its extent, at others it is limited to the formation of raised points or patches which here and there stud its surface. These conditions apparently indicate a corresponding diffusion or limitation of the inflammation. In hke manner, the state of surface of this stratum is liable to great dif- ferences, being sometimes level and compara- tively smooth, while in other instances it offers every conceivable degree of roughness, from a trifling irregularity of surface to those long, large, and shaggy processes which are so often seen in acute pericarditis, and which have been well compared to the vilii of an ox's tongue. Considerable difference of opinion prevails as to the exact mode in which this curious state is produced : thus some imagine it to be the result of the mutual movements of the visceral and parietal layers of the membrane ; or that, in separating from each other, they draw out a thread of the viscid and coagulating paste, until it breaks, and thus leaves a projecting process attached to each of these surfaces. But the fact, that an elongation very similar to that of those processes is seen in solitary warty deposits on the valves of the heart, in situations where no such physical causes as this can be supposed to obtain, renders this explanation more than doubtful ; and, on the whole, the interpretation of Vogel seems much more probable, that they result from a want of uniformity of the effusion in the first instance forming small scattered patches of lymph, on and around which, as around foreign bodies, the subsequent continuous effusion tends to deposit itself. The first layer of fibrine thus deposited on the inner surface of the membrane forms, if it is complete, a kind of sac, in which the more serous part of the exsudation is included. But this liquid part generally contains a con- siderable further portion of the fibrinous element ; and the resulting phenomena appear to depend in some measure on its amount. Thus, if the exsudation be almost wholly of plastic material, large irregular masses of fibrine are found in the cavity of the mem- brane ; the serous fluid being only in sufficient quantity to moisten these loose coagula. If the serum be superabundant, the fibrine may remain almost or entirely dissolved in it ; or may only be visible as a slight disturbance of its transparency', imparting to it a white colour, or forming a few scattered flakes which float hither and thither in the fluid. A medium between these two extremes is perhaps more common, in which the plastic element coa- gulates in a loose irregular kind of net-work, the meshes of which enclose the serum. And with this more general precipitation there is usually a special deposit upon the peripheric or oldest layer before mentioned, which imitates its irregular or shaggy form. But as this process of coagulation is often a very slow one, the extent of lamination is by no means limited to these two layers ; five, ten, or twenty thin strata often appearing to be laid down from the fluid, one after another. In all these cases, the denser and stronger layer, in contact with the surface of the serous membrane, is the original plasma, the first which was deposited, and the earhest to be organized. Rarely the completeness of this coagulation leaves the serous part entirely SEROUS AND SYNOVIAL MEMBRANES. 535 devoid of fibrine, and, in respect of composi- tion, closely resembling some of the dro[)sical fluids previously described. Organization of the effusion. — In some very few instances, in which the exsudation is only in a limited quantity, absorption occurs prior to the deposit of the fibrinous portion ; but after this change has once occurred, and the fluid has been separated into a serous and solid portion, the former only is susceptible of removal, the latter or fibrinous constituent being either absolutely incapable of absorption, or, what is perhaps more probable, being re- moved so slowly as to be replaced by the organization of new tissues long before its withdrawal is completed. When the quantity of fibrine is small, organization is on the whole both less frequent and rapid. Still it may occur; and even where this substance is re- tained in solution, the fluid containing it is susceptible of this change. But although the products of inflammation generally progress towards organization, yet the steps and results of this further develop- ment differ very widely from each other. In the majority of these effusions, one of two processes occurs. In one class of cases, the free surfaces of the membrane are glued together by the coagulable lymph effused upon them ; and this cementing substance is either itself converted into a permanent structure which obliterates the cavity, or it forms a nidus or stroma in which the structure is developed. In another set of cases, the plasma experiences a rapid development into a number of cells, floating in a thin fluid. These are termed the adhesive and suppurative forms of in- flammation respectively ; or sometimes, with perhaps less correctness, the " terminations " of this process. In some instances, however, a process similar to the first of these takes place inde- pendently of adhesion. Sometimes, the plastic layer on the inner aspect of a serous mem- brane experiences a transition into a structure which resembles areolar tissue, and presents an iiTegular or shaggy surface, like the fibrine for which it is substituted. In other instances, a thinner layer, with a more regular surface, is formed, and clothes the normal structure with a new serous or fibro-serous membrane, which can readily be peeled off from the subjacent tissue. This layer is rarely of unifoi'm thickness, and when limited to small isolated patches forms the " white spots " which are so frequently seen in the peri- cardium. In these instances, the effusion is evidently in very small amount, and probably consists almost wholly of the plastic materials of the blood, with very little accompanying serum. Another class of cases may be mentioned here which, in respect of the absence of ad- hesion, are somewhat similar to this condition. They differ from it, however, in the fact of their presenting a large quantity of a serous or little fibrinated fluid, and in the very slow organization of their solid matter, which, in some instances, advances so little in a con- siderable lapse of time, that we might almost doubt the occurrence of any further deve- lopement. In these instances, the small amount of plastic material present is irregu- larly deposited here and there in the shape of small granules of fibrine which are scattered over the surface of the serous membrane. This condition frequently occurs in the peri- toneum, and has been called " tubercular peritonitis." It offers, however, such wide distinctions from the really tuberculous in- flammation, that it is difficult to imagine that the term was ever used to express more than the shape of the deposit ; and in order lo avoid the confusion caused by designating two such different diseases with one name, Mr. Simon has suggested that of " granular peritonitis," a term which avoids this ob- jection, but equally indicates the peculiar form which the fibrine exhibits. When the plastic material has been mainly deposited on the walls of the cavity, and has included a considerable quantity of serum in its interior, an absorption of this fluid neces- sarily precedes the contact and adhesion of the opposed surfaces. But in the more diffuse and irregular coagulation previously alluded to, in which the serous portion occupied the meshes or interstices of the fibrinous net-work, the latter may become organized, and may thus form cyst-like cavities, which are perma- nently filled with this fluid. In most instances, the serum having been absorbed, and the walls of the cavity having been united by coagulable lymph, the latter becomes slowly organized into a substance which resembles areolar tissue, but contains comparatively little of the yellow fibrous ele- ment. Cotemporaneously with this change, vessels are developed in the mass by a series of processes, which, in all probability, closely ap[)roximate to those of their formation in the embryo. The resulting structure occu- pying what was previously the cavity of the serous membrane, effectually prevents the re- petition of such an effusion ; although there is no reason to believe that it confers an ab- stract immunity as respects the inflammatory process. The supjnirative injiammaiion of the serous membranes frequently offers, in its symptoms or causes, few differences from the adhesive variety; but the formation of pus is sometimes discoverable at so early a stage of the dis- order, as to render it doubtful how far it may not be considered, not so much a mere form or termination of the disease, but an inflamma- tion sui generis. Where pus has been re- ceived into the bloodvessels, and circulated with their contents, large collections of this fluid are sometimes seen in these tissues : these are, however, to be distinguished from the suppuration which occurs primarily as the result of an inflammatory process. In the latter case, the cavity of the inflamed serous membrane is usually lined by a soft, irregular, and membranitbrm exsudation, resembling the wall of an abscess, to which the altered tissue may, under these circumstances, be fairly com- 536 SEROUS AND SYNOVIAL MEMBRANES. pared. The appearances of the pus present the varieties met with in this fluid generally. In the most favourable cases, the fluid ra- pidly diminishes in quantity ; and the pus-cells, which are incapable of further organization, disappear, the substances which compose them being, in all probability, absorbed subse- quently to the breaking up of their structure ; while the remaining parts of the exsudation become organized together with the adhering walls of the cavity, and result in the complete obliteration of the serous structure. In other instances, the suppurative process takes a more unfavourable course ; the pus assumes a sanious appearance and a very of- fensive smell ; and, finally, after ulceration or sloughing of the serous membrane, is dis- charged through the opening into the cavity of the viscus, or into a neighbouring serous membrane, or on the surface of the body. Sometimes this process appears to be modi- fied by the occurrence of a less ccmiplete ab- sorption. The pus, deprived of certain of its constituents, is slowly transformed into a rnortar-like mass, lining the membranous wall by which it appears to be secreted. The sandy or gritty consistence of this substance shows that it contains chiefly the inorganic constituents of the exsudation ; and sometimes the fluid, gradually thickening, passes into a cheesy pultaceous mass, and thence, by long duration, into a cretaceous substance, resem- bling that into which tubercle often degene- rates. The so-called chronic inflammation presents no differences which can be called essential ; most of them chiefly referring to the duration and intensity of the process, rather than to any peculiarities in its nature and appearances. For instance, if the general symptoms are less prominent than usual, and the disease pro- gresses slowly, with frequent remissions and exacerbations, it is called chronic." So, also, the same name would be applied to a case which, originally "acute" in the intensity of its symptoms, and the rapidity of its progress, had overpassed the violence of the first attack ; the effusion remaining with diminished con- stitutional disturbance. Or a recurrence of the inflammation, pouring forth a new effu- sion in and within the already dense and har- dened layer of a previous exsudation, is called chronic. In such a relapse, the unorganized exsudation has been said to be the seat of the secondary inflammation ; but it may be ques- tioned how far the inflammatory process can occur in a tissue which is as yet unprovided with vessels : and even were the absence of these as complete as it seems to be, the in- flammation of the lymph would scarcely be a necessary supposition, since it would be dif- ficult to deny the possibility of a physical transudation of fluid, derived from the nearest vascular surface, or that of the original mem- brane. Besides these divisions of inflammation ac- cording to its duration and results, there are others, in which the process is compli- cated^ by its occurrence in connection with other diseases, or by its dependence upon some specific cause. Amongst these the " haemor- rhagic " eff"usion, first recognised by Lgennec, holds a very conspicuous place. In this dis- order the inflammatory exsudation is mingled with more or less blood, which communicates its colour and appearances to the whole mass, in a degree varying with the quantity in which it is present. By longer duration, it separates into two parts : a peripheric layer of whitish or slightly-coloured lymph, which covers the serous surface ; and a fluid which contains the greater part of the blood corpuscles and serum, and is included in the cavity formed by the plastic layer. This liquid |)ortion is only capable of a very slow absorption, and prior to this event it passes through many gradations of colour and appearance. Ge- nerally, it slowly loses its red colour ; but in the case of the hasmorrhagic inflammations of the peritoneum, it very frequently becomes darker, and, finally, almost black ; a change which seems due to the action of the intes- tinal gases. This conjunction of inflammation and ha2morrhage occurs in many diseases, but with the greatest frequency in tubercular ca- chexia, in fevers, and in other exanthemata. In all these disorders, the mass of the blood is greatly affected, and in many of them suffi- ciently so to exhibit marked deviation from the composition and properties of the healthy fluid. And in addition to these, the gene- ral conditions of its occiu-rence, Rokitansky * points out a local circumstance which greatly favours its access ; viz. the previous existence of a plasma, in which organization is com- mencing. And he refers this aptitude for haemorrhage to the probable state of its vas- cular apparatus, which, in this early stage of its development, offers simultaneously the greatest delicacy in the texture of its walls, and a deficiency of anastomosis with the neighbouring vessels ; two conditions which would respectively diminish its capacity of re- sistance to any distensive force, and increase the amount and duration of this distension. And in illustration of this his opinion, it may be pointed out, that a granulating surface on the exterior of the body seems closely to imi- tate these local conditions; while the resulting haemorrhage, often traceable to the congestion mechanically producible by posture, often de- pending on exciting causes of a more recon- dite nature, affords a parallel to some of the effusions noticed above. The events of inflammation are mainly in- cluded in the preceding sketch of the effusion which constitutes its most important feature : in this manner adhesion, suppuration, ulcera- tion, and more rarely sloughing, occur. But they also happen, though with less frequency, as secondary affections of the serous mem- branes, in connection with diseases of the viscera or cavities which they cover. Thus, a morbid process in the immediate neighbour- hood of a serous membrane frequently causes * Haudbuch der Pathologischen Auatomie, Band ii. S. 2ti. SEROUS AND SYNOVIAL MEMBRANES. 537 a slight effusion, which is followed by an ad- hesion of its visceral and parietal layers ; an elfect which is usually attributed to an " irri- tation " of the part by the disease. And as this process generally precedes any similar extension of ulceration to these membranes, it has the salutary result of sealing up their in- terior, and thus of preventing what would otherwise be a serious or even fatal effusion into their cavity. Their destruction by the communication of an ulcerative process in their immediate proximity may be called by the same name ; but it often more resembles sloughing in the rapidity of its course, and in the imperfect absorption of the broken down textures. So also where softening of these tissues happens, it almost invariably depends upon an action which primarily affects the subjacent viscera, and gradually implicates their serous covering. Tuhercle. — The deposit of this morbid product in the cavity of a serous membrane constitutes but a part of the general tuber- cular cachexia; and in the majority of in- stances, it only occurs after the disease has been localised in some other organ ; often, indeed, after it has already implicated the respiratory apparatus. And even in those cases in which its symptoms precede other manifestations of the disease, it appears ex- tremely probable that the lymphatic glands of the immediate neighbourhood have been the original seat of the deposit, and that from thence it has, as it were, extended to the par- ticular serous membrane. Occasionally, the tubercular matter is de- posited in and amongst the effused products of inflammation, so that the two processes appear to merge into each other, with a similar mingling of their products. This occurrence of tubercle in connection with inflammatory exsudation has been minutely described by Rokitansky, who considers that a complete metamorphosis of the latter substance into the former does, in some instances, obtain. But from the difficulty of procuring direct evidence upon this point, i. e. of examining different portions of the same effusion at different periods of its dura- tion, one may be allowed to doubt whether such a transmutation, or even a substitution, is really effected. Generally speaking, the coexisting inflam- mation plays a more subordinate part. Where the tubercular matter is thus compa- ratively uncomplicated, it occurs in the form of greyish semi-transparent granulations, of about the size of a millet-seed, or rather larger. The situation of these is usually on the inner surface of the membrane, which they render irregular by their presence, so that on removing a tubercle (which is easily peeled off from the subjacent texture), a depression of a size which corresponds to it is exposed, in which the serous membrane has lost its smooth and shining character, and has become dull and somewhat opaque. Besides this, which is the ordinary form of tubercle in these textures, other and smaller varieties often occur : and where a large quantity of the deposit is present, more or less exsudation unites the whole into a layer ; in which, however, the granidarity of their developement can still be discerned. Usually, a certain amount of serous fluid is also present, the quantity of which has some relation to the extent of the disease. In the peritoneum, however, its quantity is for the most part insignificant ; and the cavity of the serous membrane is completely filled by a thick and solid, yet granular mass of tuber- cle, by which the viscera and abdominal I)arieties are completely matted together. Sometimes, but rarely, the texture of the serous membrane itself, or the subserous areolar tissue, becomes the seat of the de- posit ; in these cases its quantity is small. The after-changes of tubercle in these tissues may lead to suppuration and ulceration, or to a slow absorption of the organic constitu- ents of the mass, and a cretification of the remainder ; but in the greater number of cases, the patient dies of the general disease without either of these events having hap- pened. Cancer of these tissues is comparatively rare ; and of those instances which do occur, many are scarcely affections of the serous membranes themselves, but ought rather to be considered as secondary, and dependent on a mere local proximity. Thus, a neigh- bouring cancerous tumour, by the progress of its growth, comes into contact with a serous membrane, and, as its size increases, gradually implicates this structure in its own diseased mass. Sometimes they are primarily at- tacked ; yet even here, other organs gene- rally suffer at the same time, and either com- plicate or mask the local disease. The carcinomatous deposits themselves offer few special peculiarities of appearance. The harder or scirrhous forms are seldom seen ; the softer varieties, viz. the gelatini- form or areolar, the medullary, and the me- lanotic, being those to which they are most liable. For a description of these the reader is referred to the article Adventitious Products. Ossification of the serous membranes is also infrequent. Like the same process else- where, the deposit of bony matter never occurs alone, but is a very slow change, which appears to require the existence of a previous tissue. Hence, it is hmited to two forms, neither of which primarily affect the cell-growing membrane. In the first, the fibrinous exsudation of a preceding inflam- mation is gradually transformed into ossific matter. In this case, the shape of the de- posit is rough and irregular, and sometimes it forms a kind of nucleus, which occupies the centre of the tough fibrous mass. Its appearances sometimes approximate to those of the cretification before alluded to, as pos- sibly do the several processes which form these substances. In the second variety, the subserous and neighbouring areolar tissue is occupied by the deposit ; but here also 538 SEROUS AND SYNOVIAL MEMBRANES. a fibrous or fibro-cartilaginoiis thickening, which is itself the developement of an exsu- dation, is probably the immediate seat of the change ; and a variable quantity of this mor- bid tissue is generally seen around and upon the bony matter. The shape which, under these circumstances, it assumes, is somewhat more regular than that of the preceding variety, it being often flattened and extended in thin plates, the roughly tuberculated sur- face of which is, for the most part, parallel with the surface of the membrane. The pleura is the most frequent site of these ossifications, as it is also of the adhe- sions in which they mainly occur : but they are also found in the subarachnoid tissue and pia mater ; and, more rarely, in the peri- toneum and the synovial sheaths of the ten- dons. Ci/sts are often found in these membranes, but their great differences of nature and causes claim a longer notice than can be accorded in this brief sketch. Three chief varieties may be distinguished. One of these is inhabited by parasitic animals, as the echi- nococcus. These are usually found in great numbers, and may occur in any of the serous membranes, although the peritoneum is their most frequent locality, probably from its proximity to the intestine by which they are introduced into the body. Sometimes they occupy the cavity of the membrane, and are in contact with its interior by a slightly flat- tened part of their surface; in other instances, they project into the cavity, carrying the membrane before them ; and at least one layer of their wall is formed by lymph de- rived from the neighbouring vessels. Ano- ther form is not recognised as parasitic, but in the present state of our knowledge might rather be described as a gigantic cell, which often includes a vast progeny of smaller ones. The whitish powder which some of these contain, may frequently be seen to be com- pletely composed of small cells, which are de- void of a nucleus, of uniform size and sphe- rical shape, and exhibit a clear sharp outline. These characters alone would, perhaps, indi- cate their merely cellular nature, as above stated; but the general appearance of these contained globules is suspiciously like the ova of entozoa. In other cases, the included cell again includes a smaller one, and this yet another, so as to form a series of concentric hollow spheres ; an arrangement which has named them as the pill-box hydatid. In their general appearances, they closely resemble the preceding variety. The fluid contents of both are Hmpid and transparent, and are composed of water, with blood salts (chiefly chloride of sodium), and an exceedingly small quantity of albumen. Yet the eftiision of this apparently harmless fluid into the serous cavities gives rise to an inflammation of the greatest violence and fatality. In a third class of cases, the cysts are usually in much fewer numbers than the preceding : they occur for the most part in the neighbourhood of the female reproductive organs ; and this their situation, together with their contents, which often consist of teeth, hair, bone, fat, and other products of an abortive develop- ment, sufficiently indicate a relation to the generative process. The fluids which they contain are albuminous, often sufficiently so to possess a glairy consistence. They exist w ithin the cavity of the serous membrane, or in its texture, indifferently ; when developed in or beneath the subserous areolar tissue their gradual enlargement causes them to reach the free surface of the membrane, and then to dilate and extend this tissue before them, until finally the cyst, still covered by the serous layer, hangs freely in the cavity by a more or less elongated peduncle, w hich is formed by this covering where it becomes continuous w^ith the rest of the serous membrane. The subserous areolar tissue has been men- tioned as implicated in most of these diseases ; but other morbid conditions are not wanting, in which it appears to be affected without the essential participation of the remainder of the tissue. Such are the little masses of fat which are occasionally found projecting into the serous cavities ; they are covered by the smooth and apparently healthy membrane, and their form is generally pedunculated, or sometimes ramified and arborescent. The development of this shape corresponds with that of the subserous cysts just mentioned. The fibrinous Pacchionian bodies of the cere- bral meninges have been similarly explained as arising from the pia mater, and gradually invested with a layer of arachnoid which becomes converted into a peduncle, the rupture of which leaves them adhering to the dura mater, or even projecting into the longitudinal sinus. Loose cartilages. — The cavities of the serous and synovial membranes sometimes contain morbid products in the shape of certain free or unattached substances, which, from their usual appearance and consistence, are best knowm as " loose cartilages." The most frequent situation of these bodies is in the knee-joint, and next to this, in the synovial sheaths of the flexors and extensors of the hand or foot ; but they are not uncommonly found in the subcutaneous bursae over the patella, trochanter, or acromion. More rarely they are seen in connection with the serous membranes; for instance, in the tunica va- ginalis testis, or in hernial sacs. They may also exist in the diarthrodial species of false joints. Their appearances offer great variety in different cases. In some instances, as often happens in the knee-joint, only one, or per- chance two such bodies are present. Here they are of considerable size, attaining the magnitude of a large bean or almond ; their shape is a more or less flattened oval, and their surface is smooth and slippery. Their consistence is firm and elastic, their appear- ance whitish and cartilaginous, their substance uniform and structureless. When comparatively recent, or of only a SEROUS AND SYNOVIAL MEMBRANES. 539 few weeks' or months' standing, they may vary somewhat from this description by the possession of a rough surfiice on one side, which indicates the seat of their previous attachment to one of the bones of the leg. The observations of Cruveilhier * have furnished us with a knowledge of the stage which, at least in some instances, immediately precedes this condition. He has shown that, in some cases, the development of these bodies occurs in the subserous or rather subsynovial tissue ; that their enlargement carries forward the synovial membrane ; and that a peduncle is thus formed, the rupture of which sets them free, in the articular cavity. There are other cases which possibly re- present a different class, and which are dis- tinguished from these by the characteristics of the greater number, lesser size, and, for the most part, much softer consistence of these bodies. Their general features have long been known to anatomists, and recently the minute descriptions of Bidder-)- and HyrtlJ have added important, though appa- rently conflicting, details concerning them. In the case which Bidder has narrated, the morbid product was removed from the knee-joint during the life of the patient, so that the appearances of the synovial mem- brane are necessarily wanting. The mass consisted of granules, the shape of which was always a flattened oval ; and their size oflfered a similar uniformity, the length of the oval being about one-eighth of an inch, and this about double and treble its width and depth respectively. Their surface was smooth and shining, their colour yellowish-white, and a viscid fluid in sparing quantity (probably synovia) united them into small clumps or masses. In consistence, they were softish, yet highly elastic, resuming their original size and shape immediately after the removal of a flattening pressure. A microscopic exami- nation showed them to consist of an uniform substance, and to be entirely devoid of all traces of organization. Their chemical re- action was that of an albuminous solid ; — viz. they were unchanged by water or ether, were shrunken by the application of alcohol, and were swelled out into a transparent mass by acetic acid. The substances described by Hyrtl differed in many important respects from the preceding granules. The synovial sheath of the flexor tendons was distended, so as to form a protuberance above and below the annular ligament of the wrist. Pressure on either of these swellings alternately gave rise to a predominance of the other one, and was attended by a kind of crepitating sound. On laying open the sheath, its interior was found to be occupied by upwards of a hundred * Patholog. Anat. ii. 2. p. 211. t Henle und Pfeuffer's Zeitschrift, 1845, Band iii. Ueber Entstehung fester Korper in den von Sy- novialhaliten gebildeten Hohlen. X Oesterreiche Medizinisclie Jahrbucher, Bd. xxxix. S. 261. Anatomische Untersuchung einer so- genannter Hydatiden Geschwulst des Schleunbeutels der Beugesehuen am Carpus. small bodies, which in their colour and general appearance seem to have greatly resembled those described above ; but their consistence appears to have been softer, their size less uniform, varying from that of a hempseed to a lemon-pip, and their flattened shape was, in most instances, altered by the possession of an elongated extremity, although others were more globular. The sac itself exhibited very interesting appearances. The tendons, where they passed through it, were greatly diminished in bulk. The parietal portion of the sac appeared to consist of two layers, a serous and a fibrous, the latter of which was dense. (Probably this appearance was partly due to a condensation of the neigh bourino; areolar tissue by pressure mto a membranous form, similar to that seen in the sac of an aneurism.) The synovial membrane, where it covered the tendons, was looser than natural, and had lost its smoothness and polish, while in many places it had acquired a villous appearance. In the subserous areolar tissue, httle knots were seen, many of which projected into the sac, carrying before them a covering of the serous membrane ; others of them had rather a constricted neck; and, finally, in others this constriction had increased so as to form a peduncle of little more than the thickness of a hair. The severance of this connection brings these bodies to the same condition as the granules which were found free in the cavity ; but the bulk of many of these was larger, while those yet in connection with the sac were uniforrhly of small size. This larger size of the un- attached bodies was also noticed by Mor- gagni. The minute anatomy of both the free and attached substances was the same. Their surface was clothed with an epithelium of angular flattened cells, and their interior contained areolar tissue and fat, with a grumous coagulated substance. These two normal tissues, however, were not in a healthy state ; the fat cells were wrinkled, their con- tents half solidified, almost opaque, and of a sordid yellow colour ; the areolar tissue was alike destitute of regular arrangement and of its ordinary wavy lines ; while with all this was mingled much amorphous debris. Concerning the mode of formation of these substances considerable differences of opinion have prevailed, which may justify a slight notice in this place. The descriptions of Cruveilhier, Hyrtl, and others, leave no doubt as to what is the pro- cess of their development in at least a large proportion of instances. These exhibit them as aff^ections of the subserous, or rather sub- synovial areolar tissue ; while the circum- stances under which they are found, such as the arrangement of the deposit in small masses, which are plentifully scattered over a large surface, the aged and debilitated constitutions in which they are chiefly present, &c., indicate with tolerable clearness that they are the result of disease, as contradistinguished from external violence. But it may be doubted whether this expla- S40 ' SEROUS AND SYNOVIAL MEMBRANES. nation will apply to these unattached bodies universally : it seems more probable that amongst these substances are included some which have not only a different origin, but also a different relation to the synovial mem- branes. Thus, it was imagined by Hunter* that " the loose cartilages usually found in the knee-joint originated from a deposit of coagu- lated blood upon the end of one of the bones, which had acqinred the nature of cartilage, and had afterwards been separated." He conjectured that their pedunculated shape during the period of their attachment de- pended on the movements to which such deposits were liable during their soft con- dition ; and in confirmation of this he adduces an instance in which some blood effused in the abdominal cavity acquired a peduncle half an inch in length before it lost its red colour, and, when washed, exactly resembled a pendulous tumor. And as to the possibility of the transformation of such an effusion into a cartilaginous-looking substance, reference is made to an examination of joints which had been violently strained or otherwise injured, where the patients had died at diffe- rent periods after the accident. In some of these there were small projecting parts, pre- ternaturally formed, as hard as cartilage, and so situated as to be readily knocked off by any sudden or violent motion of the joint." The frequent connection of this variety of loose cartilage with external violence has long been known, and in some of these cases symptoms of local inflammation mark the period of their formation ; while, after a cer- tain interval, the accident of their separation occurs, attended by the ordinary effects on the movements of the joint. These facts, however, while they afford a great probability that external violence may operate as a cause of these growths, by giving rise to an effusion, which in some instances consists, it is most likely, of blood ; yet they do not exhibit the relation of this effusion to the synovial membrane. But it may be con- jectured from the situation and arrangement of the vessels, that a sudden hemorrhage, to any perceptible amount, would necessarily imply the rupture of this delicate tissue, and the consequent presence of the effusion in its cavity ; while a smaller or slower process would carry the membrane before it ; or, in other words, that the presence or absence of the serous covering would chiefly depend on mechanical conditions ; and that, in either case, the result would be little affected. Indeed, the synovial membrane itself cannot be considered immediately essential to the formation of these substances ; another vas- cular surface may be substituted, the result continuing the same. Thus, Sir Everard Homef mentions a case in which thirty or forty such substances were found loose in the cavity of a false joint, having apparently been * Transactions of a Society for the Improvement of Medical and Surgical Knowledge, vol. i. p. 231. f Loc. cit. mechanically broken off from a number of projecting portions of cartilage, which studded the broken ends of the bones, leaving exposed interstices. Although slight variations in the size and shape of these substances, and more considerable differences of their consistence, are spoken of, yet their description essentially coincides with that of the preceding bodies examined by Bidder. Taken altogether, these facts seem to in- dicate that the unattached substances which are found in these tissues include the products of very different pathological conditions and processes. They appear to show that morbid deposits beneath the synovial membrane, effu- sions the result of violence, and either oc- curring beneath it, or by mechanical extension in its cavity, and finally, irregularly formed cartilage, may all, under certain circum- stances, give rise to the production of these substances.* The conditions essential to their transform- ation seem to be of a twofold nature, me- chanical and physiological ; exposure to pres- sure and movement, and the presence of a synovial fluid. It is doubtful how far the ac- quisition of the peduncle noticed in some, may depend on the joint influence of their extensibility, and the mechanical violence which must be exerted on such isolated pro- minences. But the separation, whether of these, or of those seen in the false joint, is obviously the direct result of violence. Pres- sure seems an important condition, so much so, that a close relation may probably be traced between its amount and the degree in which they have assumed the cartilaginous form and consistence ; the synovial sheath, the knee-joint, and the false joint appear to present gradations in both these respects. And as to the operation of the synovial fluid, similar probabilities may be deduced. The mere permanence of these bodies seems to point out that they possess some kind of nu- trition; and the increased bulk noticed by Hyrtl in the unattached as compared with the attached substances, would still further ne- cessitate such a supposition ; their structure sufficiently denying the suggestion that the increase is due to the union of two or more. And in the case described by Hyrtl, the struc- ture of these bodies seems to show that the results of a previous organization are not exempt from this transforming process, but may undergo a degeneration into a cartilagi- nous substance. And in the absence of any inherent or chemical capacity of their contents for such a change, this would yet more re- quire the supposition of an agent of nutrition, which should supply the materials, if it did * I may, perhaps, mention, that since writing the above, I believe myself to have veiified the con- version of bone into these structures. The change vras partial, and the vessels seem the immediate agents of the process, since not only did a superficial stratum of caitilage occupy the Avhole surface of a pedunculated and cartilaginous structure, but a layer of nearly equal thickness surrounded the vessel in each Haversian canal. See Medical Ga- zette of Dec. 8. 1848. SESAMOID BONES. 541 not effect the metamorphosis. While the complete isolation of these bodies from the vessels which are the immediate channels of nutrition, leaves only one supposition, viz., that the synovial fluid is the pabulum from which they derive the materials essential to their permanence, growth, or alteration. The composition of this fluid as compared with their own, perhaps sufficiently warrants this conclusion. Other conjectures as to the mode of their development are offered by Bidder, such as the possible precipitation of synovia around an epithelial cell, the gigantic development of a cell, or, what much approximates to this, their hydatid nature. In certain abnormal conditions of the ar- ticular cartilages, peculiar appearances of the synovial membranes are seen, although it is somewhat doubtful how far they can be re- garded as essentially morbid. Thus, for example, in the ulceration of diar- throdial cartilages, it appears probable, that the removal of their substance is chiefly accomplished by the synovial membranes. Cruveilhier * narrates a case in which puru- lent fungosities of this tissue replaced the destroyed cartilages of the ankle-joint; and the general connection of hypertrophy of the membrane with ulceration of the cartilage has long been known. More recently, Mr. Good- sir's f investigations have thrown much ad- ditional light on this subject. He has shown that the preternaturally active growth of the cartilage, and the similarly rapid change of its properties and appearances, are to be regarded as inherent in this tissue itself ; that where the destruction of its substance occurs at its margin, or in the immediate neighbourhood of the vessels, a fungous enlargement or ex- tension of these accurately fits into the eroded part ; but that in the ulceration of the centre of the cartilaginous lamella, such a phy^sical adaptation is absent. From these circum- stances it seems probable that the absorption which is accomplished in the former case by the local enlargement, is in the latter shared by the vessels of the synovial membrane generally. A somewhat similar, but much less pro- minent affection of vascularity has been de- scribed by Dr. Todd J in the porcelain-like condition of these cartilages, which often obtains in the chronic gout of the aged. The highly injected vessels of the synovial membrane were covered by a whitish powder, which was doubtless a frictional detritus of the diseased cartilage. How far this con- gestive state is connected with the absorption of this powder, is unknown. ( William Brinfon.') SESAMOID BONES. By this name are designated the small bones met with in the neighbourhood of certain joints, generally in the tendons of the adjacent muscles. They * Archives Generales de Medecine, vol. iv. p. IGl. f Anatomical and Pathological Observatious. X Medical Gazette, 1847. owe their name {(rrjtrafxri ei^og) to the figure which they usually possess, resembling that of an Indian grain called sesame. But the present application of the term regards the character of their situation in the course of a tendon, rather than their form ; for in- stance, the patella is often said to be a sesa- moid bone, not because it resembles sesame, but because it is placed in the tendon of the extensor cruris muscles. This character of their situation in the course of tendons con- stitutes their chief point of interest ; it is in this that they are peculiar, and different from other bones. In the human subject these bones are usually met with only on the palmar aspect of the metacarpo-phalangeal joint of the thumb and the homologically corresponding part of the great toe, in both of which situations there are usually two. These are not constantly present, and, according to Cloquet, are not met with in children, owing, j)robably, to their becoming ossified late, though in young Ru- minants and Solipeds, as well as in other animals, I have found their ossification as far advanced as it was in the other bones. They are more frequently absent in the hand than in the foot, and in females than in males. The long flexor tendon of the thumb or great toe passes between them, and the two are bound together above and below it by dense fibrous tissue, so that they assist in forming its sheath. The sesamoid bones of the thumb are very small — usually not bigger than the half of a large pea. They have a somewhat oval out- hne, are convex on their palmar, and slightly concave on their dorsal aspect, which is arti- cular, and covered with cartilage. They arti- culate with the head of the metacarpal bone. Those of the great toe are each as large as a horse bean, of a long oval outline, convex on the plantar aspect, and presenting a concave cartilage-covered surface to the head of the metatarsal bone, to which they are adapted. The little pieces of bone, situated and shaped as above, are enclosed in the tendons of the short flexor muscle of the thumb or great toe, the fibres of which have the follow- ing relation to them : — Some of the ten- dinous fibres pass over them, and some on each side, whilst their articular cartilage, as I have verified by microscopic examination, be- comes mixed with tendinous fibres, passing on their arthrodial aspect, as it approaches the bone. The greater part of the tendon, how- ever, is inserted into their proximal, and arises again, so to speak, from their distal end. The arthrodial surface of their articular cartilage forms part of the synovial surface of the sub- jacent metacarpo phalangeal joint, and they are held in their place by the strong fibrous tissue of the common synovial capsule. Structure. — The sesamoid bones consist of finely cancellated osseous tissue, enclosed in a shell of denser bone. The main direction of the osseous columns that surround the can- celli is longitudinal, but they intercommunicate in all directions. These columns are much 542 SESAMOID BONES. stouter towards the external part than to- wards the inner or that which is in contact with the long flexor tendon. A microscojyic examination of sections, taken in the three cardinal directions, shows that they possess much the same minute structure as other similarly shaped bones. The lacunas are large and expanded*, the canaliculi dis- tributed arborescently, except a few in the immediate neighbourhood of the cancelli and Haversian canals, where they have the straight and parallel arrangement met with in the shafts of the long bones. The Ha- versian canals are but few in number, their place being plentifully supplied by the nu- merous cancelli. The dense surrounding shell is stratified parallel to the surface, very markedly so on the articular aspect, where it is thickest. At the points where tendinous fibres are attached, it appears to be laminated at right angles to the strata and the surface, as though the fibres of the tendon were re- ceived between the plaitings of osseous laminss, or conversely as though the ossification had extended up in laminge between the tendinous fibres. The lacunas that occur in this crust are mostly large and clumsy, elongated and directed vertically or obliquely towards the surface, particularly the articular surface, and all of them destitute of canaliculi ; a condi- tion met with in the superficial osseous crust of other articular surfaces, and points of attachment of tendons, especially in old sub- jects.— It is probably the form of osseous tissue that results from the ossification of permanent cartilage or white fibrous tissue ; but my researches, in order to ascertain this point, have not been sufficiently extensive. Developement (examined in young Rumi- nants).— A small mass of temporary cartilage precedes the osseous condition of these little bones. This becomes ossified from a single central point in the manner of an epiphysis, as described at page 857. Vol. III. art. Osseous Tissue. Disease and injury. — I am not aware that the diseases or accidents affecting the sesa- moid bones have ever been noticed, unless the patella be considered a sesamoid bone, which, indeed, it is in structure, by situation in a tendon, and in function. This bone comports itself in disease just as other bones do (see Knee Joint, Abnormal Anatomy). When fi-actured transversely, it presents the pecu- liarity of uniting, by white fibrous tissue, in- stead of by bone. I cannot regard this non- union by osseous tissue as resulting from au}^ deficiency of nutritive or reparative power in the patella, for new fibrous tissue is always^ and when the fracture is longitudinal, even new bone is usually, formed ; nor from want of apposition, for in many ununited speci- mens the apposition is very perfect. Osseous union, as a result of reparative inflammation, never occurs in situations where the new ma- terial of repair is not subjected to pressure, as in the skull, acromion, olecranon, heel, * See Vol. III. p. 850. fig. 452. art. Osseous Tissue. — a hole made in the scapula does not be- come filled up with bone. I therefore regard the non-union by bone of transverse fracture of the patella as due to the absence of that stimulus (pressure) which I conceive to be necessary in order to determine the repara- tive material to assume the osseous form ; whilst I attribute the union by ligament to the presence of the stimulus (tension) which I regard as necessary, in order to direct the jnetamorphosis of the adhesive lymph, or rather the mass of new corpuscles or cells, which is formed for the purpose of repair, soon after any accidental breach of continuity has been produced, towards the ligamentous form. These remarks would, of course, ap- ply to transverse fractures of the sesamoid bones properly so called, in case such acci- dents ever occur. Other sesamoid bones. — Sesamoid bones are occasionally met with in the human subject in other than the above-named situations. One is sometimes found at the distal joint of the thumb and great toe ; two at the prox- imal joint of the forefinger and second toe ; and one at the corresponding joint of the little finger and toe. There is pretty fre- quently one, or even two or three, in the lieads of the gastrocnemius, just at the posterior part of each condyle of the femur. An ossi- fication often takes place in the tendon of the j)eroneus longus, just where it doubles round the OS cuboides ; and a small bone is not un- frequently found in the tendon of the tibialis anticus, near its insertion into the scaphoid. Comparative anatomy. — Sesamoid bones at the metacarpo-tarso-phalangeal joints exist in much greater number in the quadrujjed mam- malia than in man ; and they seem to be largest in animals tnat are digitigrade in their progression. I have not had an opportunity of scrutinizing their condition in the Quadru- mana ; none are preserved in the skeletons, and as the thumbs are somewhat rudimentary they are probably absent. In the Seal, a pair is situated on the metatarsal joints of both the hallux and the fitth toe, v.hich greatly exceed the other toes in size ; but there are none in the fin-like hands. They do not exist in the paddles of the Cetacea nor in the singularly modified extremities of the Sloth. In all, or nearly all, other ^lammalia a pair occurs opposite every metacarpo- and metatarso-phalangeal joint. The two bones of the pairs are not unfrequently anchylosed together, as in the outer digit of the hand and foot of the Elephant. They are always situated in the course of the tendons of the interossei muscles. Often, however, as in Ruminants, their large size is enormously dis- proportioned to the small tendons on which they are placed, which, in this order with their muscles, are quite rudimentary, and the large sesamoid bones seem to be embedded in the sheath of the long flexor tendons. In Birds their place is occasionally supplied by large masses of fibro-cartilage. In Reptiles they are wanting. The patella exists in all placental Mammals y SEVENTH PAIR OF NERVES. 543 but is absent in many Marsupials. In Birds it is usually, but not invariably, present ; there are even sometimes tw^o, one placed above another. In those aquatic birds which have the tuberosity of the tibia prolonged npvi^ards as a large process, a patella is always found placed just behind it*, sometimes closely adapted to it, and extending beyond it so as apparently to form its summit. f No patella has been met with in any reptile. Other sesamoid bones. — Opposite the plan- tar aspect of the distal joint of the fore and hind foot of Solipedes, there is a long super- numerary bone, called by farriers the shuttle bone, placed transversely. This, like the sesamoid bones above described, enters into the composition of the subjacent joint ; a broad slip of the perforans tendon is inserted into its proximal side, whilst on the distal side a portion of the synovial capsule alone, and that not so strong as one would expect, attaches it to the ungual phalanx ; the main part of the tendon passes over it to be inserted into the ungual phalanx, leaving a cavity lined by a synovial membrane between itself and the sesamoid bone in question. This bone re- minds one of that which, as above mentioned, is occasionally found at the distal joint of the thumb and great toe in the human subject. Small bones are found in one or both heads of the gastrocnemius in all Mammalia except Man, the Seals, Pig, and all Rimiinants but Cervus, in which genus they are found, yet only in the external head of the muscle. A sesamoid bone is met with in the inser- tion of the tendo Achillis of certain Birds, as the capercailzie J ; and the tendons of the legs of birds are very commonly ossified, not, how- ever, where they correspond to the joints. Use. — Sesamoid bones serve much the same purpose as processes for the muscles that are inserted into them, without the incon- venience inseparable from a process, of giving an angular form to the joint. They also pro- tect the long flexor tendons at points where perhaps they might be injured. But after all, taking into consideration all the facts related above, and many others that have presented themselves to me in the course of this inquiry, I cannot but believe, that some higher law than that of adaptation concurs in deter- mining the presence, if not the size, of even these Httle bones. (S. R. Pitlard.) SEVENTH PAIR OF NERVES (Sie- tenter Nerv, Germ. ; Le Septieme Nerf, Fr.). In laying the foundations of the natural sci- ences, few circumstances would seem to have occasioned more serious and permanent embar- rassments than the immediate necessity of in- dicating the various new objects which they presented by specific names, and the difUculty of finding suitable ones. A nomenclature based upon their properties, would, perhaps, readily have suggested itself; but, generally speaking, the recognition of the object so * Vol. I. p. 286. t Meckel. X Vol. I. p. 288. greatly preceded the discovery of its proper- ties, that this attempt was almost impossible. In the science of anatomy, this was especially the case ; and a large proportion of the human structures were named, either according to their form, or, if this was not sufficiently de- fined, by their real or fancied resemblance to some previously known object; or failing this, by the proper names of their discoverers, however polysyllabic or uncouth they might happen to be. In some one or other of these modes, the different parts of the complicated nervous centre received their various designations. But the cerebral nerves, although very similar to each other in the outward properties of their shape, size, and appearance, yet offered, by their fewness, a sufficient ground of distinction in the application of the ordinal numbers. By denying the claims of the olfactory lobes, and overlooking the fourth and sixth, the earlier anatomists made a smaller number j but the arrangement of Willis, which is more usually adopted in the present day, counts nine of these soft round cords, and reckons them from before backwards. Yet even this apparently simple method of distinction comes far short of real accuracy. Thus, some of the so-called nerves ofJer the essential structure of nervous centres ; and include, in adtlition to the ordinary nerve- fibres, those globular vesicles which modern physiology recognizes as the generators of the nervous force. In others of them, the limited resemblance implied by this numerical ar- rangement is modified by their arising as two or more roots, which subsequently, by their junction, form one nerve. While in the seventh nerve, which forms the subject of the present article, the close proximity of two such cords during a part of their course has led to their being united under one name ; although in their distribution, properties, and functions, they present a marked contrast with each other. The facial and auditory nerves proceed to- gether from the medulla oblongata to the bottom of the meatus auchtorius internus in the petrous portion of the temporal bone. Up to this point they are included in the term seventh nerve; but beyond this situation their courses widely diverge. In conformity with these diflf'erences, the following short account will describe them separately from each other. It will first mention such of their anatomical features as are manifest on simply laying bare their surface, and will afterwards refer to the appearances afforded by a more artificial dissection or separation of their fibres. Subsequently we shall briefly examine the bearing of these their structural peculiari- ties, and the effect of their morbid changes, with a view to attempting the deduction of their function. The auditory nerve is of a considerably softer texture than the facial ; a difference which is in great part attributable to the much more delicate neurilemma by which it is enveloped, but which is, no doubt, to some extent the result of a peculiarity of its constituent nerve- SEVENTH PAIR OF NERVES fibres. From the fact of its lesser consistence, it is frequently termed the ''2^^^'^^^ mollis''' of the seventh nerve. Its apparent origin is close to that of the facial. At the upper part of the lateral surface of the medulla oblongata, a somewhat trian- gular depression exists, which is bounded in front by the olivary body, above by the lower border of the pons varolii, and behind by the restiform body. This shallow cavity has been termed by Vicq d' Azyr " the fossa of the olivary eminence," and in it appears the com- mencement of the auditory nerve. On dissecting out this origin, however, it may be separated into two portions or roots. One of these immediately penetrates the res- tiform body at a right angle to its surface, and sinks into the central grey matter of the me- dulla oblongata : while the other, continuing backwards superficially to the restiform body, winds round it to reach the floor of the fourth ventricle, where this structure is deficient. By this latter root, the nerve seems to be directly continuous with the tranverse white fascicles of the calamus scriptorius ; and near the middle fine, it sinks into the posterior part of the same grey mass of the olivary columns, into which the other portion was followed. But considerable variations appear to prevail in the degree of the visible continuity of this root with these transverse white striae. Thus Meckel and Prochaska remarked that they are sometimes wanting; while Longet* confirms their statements, and adds, from the experience of himself, Serres, and others, cases which show that not only is their number variable within certain limits, but that, even where present, they may not unite with the root of the auditory nerve, but may curve upwards at their extremity, and pass up the posterior surface of the mesocephale. One or two ex- aminations made by the author of this article seem to show that this is by no means unusual. Other and more complicated origins have been ascribed by various anatomists to the au- ditory nerve. Thus, according to Fovillef, a thin and white nervous lamina, which is con- tinued from its roots and from those of the fifth nerve, is spread over, and as it were lines, the interior of the cortical grey matter of the cere- bellum, in addition to covering the whole sur- face of the fourth ventricle and medullary velum. But in this and other descriptions of a like tendency, it seems difficult to distinguish how much of the connection observed was referrible to a mere physical contiguity of the soft nervous matter, apart from that unbroken continuity of nerve-tubules which we are pro- bably justified in predicating of the cerebral nerves and their more immediate processes of origin. From the place of its first appearance at the surface of the encephalon, the nerve passes, in a direction which is at once for- wards, outwards, and upwards, to the inner * Anatomie et Physiologic du Systeme Xerveux, torn. ii. p. 84. f Traite Complet de rAnatomie du Systeme Nerveux Cerebro-spinal. Premiere Partie. surface of the petrous portion of the tem- poral bone, where it enters the internal audi- tory meatus. In tins course, the flocculus, an isolated lobule of the cerebellum, is in close proximity with its outer side ; while on its inner side, and in front of it, is the portio dura, which slightly grooves this surface of the somewhat flattened auditory nerve. After entering the auditory canal, it con- tinues along it to its termination ; and, finally, at the bottom of the meatus, it divides into two branches. The anterior of these is dis- tributed to the cochlea ; and the posterior, which exhibits a small gangliform enlarge- ment, supplies the vestibule, dividing into three branches; one for the posterior vertical canal, another for the sacculus, and a third for the utriculus, and remaining semicircular canals. These several divisions perforate the numerous foramina which are found at the bottom of the meatus to enter the internal ear ; but as an account of their further ar- rangement with respect to the parts they sup- ply would require a description of the auditory apparatus itself, the reader is referred to a previous article, " Organ of Hearing," in which these details will be found included. The facial nerve, the " portio dura " of the seventh pair, emerges from the same depression in the restiform body which was above de- scribed as giving rise to the auditory. It is of a much firmer and harder consistence than the latter, the tubules which compose it being connected by, and included in, a firm and strong neurilemma. Its real origin is generally referred to that central grey matter of the olivary columns to which so many of the encephahc nerves are traced. It is difficult to follow it any liepth beyond these in a satis- factory manner ; but Foville considers that it may be traced in the transverse direction around the olivary column and anterior pyra- mid, and hidden beneath the lower margin of the pons varolii, to an origin from the inner border of the pyramid. He corroborates this by a reference to its comparative anatomy ; and states that the various stages of this course are successively laid bare by that diminished development of the lower arches of the pons which occurs in many of the mammalia. The description given by Morganti* somewhat differs from this, since he describes its roots as radiating by many filaments, ascending, descending, and transverse ; and the latter joining more deeply the central grey substance of the medulla oblongata near the floor of the fourth ventricle. The description of the facial nerve may be conveniently separated into three parts : each representing a distinct stage of its course, which is accurately defined by its anatomical relations to the skull. The^;',y/ of these is intra-cranial, and extends from the surface of the encephalon to the termination of the in- ternal auditory canal. The second is osseous, and reaches from the latter point to the stylo-mastoid foramen, which forms the exit * Annali Universali di Medicina. Giugno, 1845. SEVENTH PAIR OF NERVES. 545 of the nerve from the aqueduct of Fallopius. The third is extra-cranial, and includes its distribution on the exterior of the skull be- yond this aperture. In the cranium, the course of the facial nerve is comparatively short. From the restiform body it passes forwards, lying immediately be- neath and in contact with the pons varolii, and taking the same direction as the portio mollis, which is external and posterior to it. It next enters the meatus auditorius internus in company with this nerve; and finally leaves it by [)assing through the aperture at the upper part of the termination of this canal, and entering the aqueduct of Fallopius. Portio intermedia. — With this part of the auditory and facial nerves a third portion is visibly associated ; which is, in all probability, essentially distinct from both. Wrisberg first announced the existence of this nerve as a separate branch ; and from its occupying a position between the " portio mollis " and "portio dura" of the seventh, he named it the " portio media " or " intermedia." It arises by two or three filaments from the restiform body, in the same locality as the neighbouring facial nerve, from which its deeper origin can scarcely be separated. Fo- ville, however, describes its ultimate visible fibres as traceable to a situation which is in- termediate between that of the facial on the one hand, and that of the auditory on the other. He thus considers these three nerves, the facial, intermediate, and auditory, as aris- ing respectively from the anterior pyramid, the olivary column, and the restiform body ; or to use his own language, from the anterior, the lateral, and the posterior tracts of the me- dulla oblongata. Morganti's view of its origin closely approximates to this ; but he places it more in connection with the vestibular nerve, and hence more externally. But whatever may be the differences of opinion as to its exact mode of commencement, it is tolerably agreed that it is in very close proximity to the facial nerve, so much so as at first hardly to be separable from it ; and that, at a further stage of its course, it is attached to the vesti- bular branch of the auditory nerve. Con- cerning its behaviour subsequently to this point, anatomists are less unanimous. Thus, some imagine that it continues engaged in the auditory nerve, and accompanies it into the internal ear. Others regard it as returning to the facial nerve, and passing with it into the aqueduct of Fallopius. It is, however, suffi- ciently evident, that the only correct foundation of any of these views must be anatomical ; and since this method of investigation requires not only the artificial unraveUing of the trunks, but also necessitates a frequent reference to portions and branches of the facial, as yet un- described, its consideration is deferred until these shall have received some notice. In the temporal hone. — The facial nerve, entering the aquaeductus Fallopii from the internal auditory meatus, passes, for a very short distance, in a direction forwards, out- wards, and slightly upwards, until it reaches VOL. IV. the margin of the hiatus Fallopii on the upper surface of the petrous bone : it then suddenly bends backwards upon itself in the horizontal plane. Its next curve differs from the preceding both in character and direction, being much more gradually effected, and occu- p}ing a vertical plane. The termination of this bend reaches the perpendicular, and opens by the stylo-mastoid foramen on the under surface of the petrous bone, or between the styloid and mastoid processes. In the middle of this course the osseous tube of the aquaeductus Fallopii projects into the cavity of the tympanum ; and the nerve thus passes successively along its roof, above the fenestra ovalis, and then behind the pyramid on the inner side of the cavity ; and, finally, down its posterior surface. At the anterior of the acute angle formed by the first bend of the facial nerve in the aqueduct of Fallopius, it experiences a slight enlargement, which has been called, from its position and shape, the " intumescentia genu- formis." A dense and strong neurilemma here ensheaths the nerve, being a prolongation of dura mater, which is sent inwards on a minute vessel from the middle meningeal artery to enter the canal at the hiatus Fal- lopii. The swelUng itself is of a greyish-red colour, but it is somewhat obscured by this thick covering of fibrous tissue. Its nature will be spoken of hereafter. Just at this point, the swperficicd petrosal nerve is connected with the facial. Tracing it forwards from the intumescence, it is seen to pass at once through the neighbouring hiatus Fallopii, and thus it immediately gains the interior of the skull. Within the cranium it passes forwards, downwards, and inwards, lying in a groove on the outer or anterior surface of the petrous bone, and situated be- neath the Gasserianganghon of the fifth nerve. According to some anatomists, it occasionally passes amongst or through the meshes of the gangliform structure. Still beneath and in- ternal to the ganglion, it is next placed im- mediately external to the internal carotid artery, where this vessel, emerging from the canal of the same name in the temporal bone, springs vertically upwards to form the com- mencement of the posterior limb of the sig- moid turn on the side of the sphenoid. It thus enters the foramen lacerum basis cranii, perforating the cartilaginous substance which closes this bony orifice ; and in this manner it gains the posterior extremity of the vidian canal, which opens into the anterior aspect of this irregular opening. Finally, it continues along this canal to its anterior termination ; and is then prolonged horizontally forwards for a short distance to join Meckel's ganglion, which occupies this part of the spheno-palatine fossa. Another nerve comes off' from the same knee-shaped bend of the portio dura ; and as it appears from the same horizontal slit, or hiatus Fallopii, w hence the preceding emerged, and occupies a very similar position with re- spect to the temporal bone, it has also been named *' superficial petrosal," but is distin- N N 646 SEVENTH PAIR OF NERVES. guished, from its lesser size, as the " small petrosal nerve." From the hiatus it is con- tinued forwards and slightly inwards for about half an inch, running along the same surface of the temporal bone, but placed a little ex- ternal to the preceding nerve. Arriving at the greater wing of the sphenoid, it perforates the bone by an oblique and minute orifice, which is situated between the foramen rotim- dum and ovale : and appearing on the inferior surface of the base of the skull, it immediately unites with the otic ganghon which lies on the inner surface of the third division of the fifth. During the latter part of this course it is ac- companied by a filament from Jacobson's nerve of the glosso-pharyngeal. This branch, however, leaves the tympanum by a special canal, and is next placed externally to the lesser petrosal nerve on the petrous bone ; but, finally, it joins or runs with it to enter the same ganglion. A branch to the membrane ivhich closes the fenestra ovalis is sometimes described as coming from the facial, where it passes, in the aqueduct, above this orifice. The minute filament to the stapedius muscle is the next branch of this nerve. It leaves the portio dura and aquseductus Fallopii at about the middle of their second or vertical curve, or nearly on a level with the base of the promontory ; it next enters a small canal in this prominence, which conducts it to the proper osseous cavity for the muscle: it then breaks up and is lost in its substance. The chorda tympani, the next connection of the portio dura, is a much larger nerve than any of the preceding branches ; it leaves the trunk of the facial at a distance of about the third of an inch from the stylo-mastoid fora- men. Tracing the portio dura in the upward direction, it is first seen to experience a slight thickening, and gradually, by the increasing laxity of the connecting areolar tissue, a to- lerably large branch seems to extricate itself from the trunk at a very acute angle. Di- verging still more, it now altogether quits the aquaeductus Fallopii, and enters a short canal which is appropriated to it, and which is placed anteriorly and externally to the former cavity, occupying the base of the promontory. While yet at a considerable distance from the apex of this eminence, the nerve emerges from its canal by an orifice very near the osseous ring to which the tympanic membrane is fixed. It now crosses the tympanum from its an- terior to its posterior part, and lying close to its outer wall, but covered by a reflection of its mucous membrane, and ascending as it goes, it passes between and at right angles to the long process of the incus and the handle of the malleus, to reach the processus gracilis of the latter bone ; along this process it con- tinues during the remainder of its course in the tympanum. It next leaves the anterior wall of this cavity, and occupies a minute canal in the petrous portion of the temporal bone ; but it is still in close proximity to this process of the malleus, being only separated by a small interval of bone from the Glasserian fissure which contains it. It is next seen ex- ternal to the cranium, after coming through the aperture of this canal anteriorly and in- ternally to the fissure. In the remainder of its course it hes deeply in the pterygoid fossa beneath the ramus of the inferior maxilla, and is directed for about an inch downwards, for- wards, and inwards, beneath the spinous process of the sphenoid, and the internal la- teral ligament of the lower jaw attached to it, to join, at an acute angle, the outer side of the gustatory branch from the third division of the fifth. Very near the termination of the aqueduct of Fallopius, a minute twig connects the facial and vagus nerves. Following it from this cavity, it is seen to enter a small pore on its anterior surface, which conducts it by a short canal to the under surface of the petrous bone, where it emerges a very short distance in front of the stylo-mastoid foramen, and be- tween it and the jugular fossa. The nervous filament now turns inwards and forwards in front of the jugular vein, and terminates by connecting itself with the pneumogastric, just below its ganglion in the dura mater of the foramen lacerum posticus. Besides these branches of the facial within the aqueduct, it appears pretty constantly to give off, while yet contained in this canal, a filament which passes inwards behind the jugular vein, and joins with the glosso-pharyn- geal just below the ganglion of Andersch. Longet states that this branch, after its junction with the glosso-pharyngeal, may ge- nerally be tracetl to the digastric or st\ lo-hyoid muscle, in which it often unites for the first time with this nerve by a kind of plexiform arrangement. External to the cranium. — On leaving the Fallopian canal, the facial nerve immediately enters that portion of the parotid gland which dips downwards behind the styloid process to reach the structures lying deeply at the base of the skull. The nerve next continues through the substance of the gland, bemg directed for- wards and inwards to about its middle, where it divides into its temporo-facial and cervico- facial portions, the ramifications of which cover the whole side of the face, with part of the neck below and the head above. In its short course previously to this bifurcation, it gives off three branches, the posterior auri- cular, the digastric, and the stylo-hyoid nerves. The posterior auricular, the first branch of the facial without the skull, passes upwai'ds from the trunk of the nerve, and turns round the front of the mastoid process, lying at first rather deeply in a depression between the au- ricle of the ear and this prominence, and being enveloped in a dense cellular tissue. Having gained the side of the head, it divides into two branches ; one of these continues back- wards in the horizontal direction, above the insertion of the sterno-mastoid, and crossed by the lesser occipital nerve of the cervical plexus, to reach the posterior belly of the occipito- frontahs muscle, which it supplies : in this course it is covered by a dense fascia, and is SEVENTH PAIR OF NERVES. 547 in close proximity to the artery which bears the same name. The remaining branch of the nerve takes a vertical direction, ascending perpendicularly behind the ear through the fleshy bundles of the retrahens aurem. To this muscle it is chiefly distributed ; but a few of its filaments continue to the posterior sur- face of the auricle, probably to supply its transverse muscular fibres. The trunk of the posterior auricular nerve, or some one of these its branches, is usually found to be joined by filaments of the great auricular nerve from the cervical plexus, and more rarely by some twigs from the lesser occi- pital branch of the same plexus. Arnold also describes a filament of the auricular of the pneumogastric uniting with it. The two following branches not unfre- quently arise by a common trunk. The di- gastric, the larger of the two, leaves the facial nerve to penetrate the posterior belly of the digastric muscle, and supply it with many filaments. One of its branches, of more con- siderable magnitude, perforates its substance, and passing directly inwards, joins the glosso- pharyngeal immediately on its emergence from the skull. Other filaments of smaller size are said to join the superior laryngeal of the pneu- mogastric. The stylo-hyoid branch, leaving the trunk of the portio dura near the preceding, passes downwards, forwards, and inwards ; crossing the styloid process obliquely, then running along the upper border of the muscle, and finally penetrating its fibres to be distributed to its interior. It is beheved to unite, by nu- merous minute twigs, with the sympathetic around the neighbouring carotid vessels. At the place of its division, the nerve occu- pies a position in the parotid gland which is superficial to the many other vessels and nerves found here ; and especially, at right angles to the external jugular vein and carotid artery. The temporo-facial (livisio7i or branch is larger than the cervico-facial ; it passes forwards and upwards over the condyle of the lower jaw, and joins, towards the zygoma, with one or two large branches of the auric ulo-temporal nerve. This comes from the third division of the fifth in the pterygoid fossa ; and the place of its union with the portio dura is in close proximity to the external carotid artery. The intimacy of the junction which connects the two nerves has probably led some anatomists to describe this temporo-facial branch as giving many filaments to the front of the ear. These, however, with many others which ramify in the gland itself, belong to the associated branch of the fifth, and not to the portio dura. Beyond this its junction with the fifth, it is no longer possible to trace any special nerve, or to indicate its subdivisions by names, since, on the masseter, a succession of diverging branches are given off from it, each of which, by uniting with its neighbours above and below, and giving off fresh ramifications from the branches of union, forms part of a com- plicated network, in which the original con- stituent branches, and the respective shares which they take in the new loops, can scarcely be recognized. Cruveilhier and Bonamyhave traced this looped arrangement still more minutely, having followed it into the smallest branches of the nerve, and especially into those which supply the orbicularis ; and it has been likened by them to the mode in which the mesenteric arteries break up to reach the intestine. Notwithstanding this free communication, however, the different portions of this re- ticulated arrangement may be conveniently regarded in succession, in order the better to appreciate their distribution. Superiorly are the temporal branches ; these emerge from beneath the upper border of the parotid, and cross the zygoma to be distri- buted to the superficial muscles of the auricle, the attoUens and attrahens aurem, and to the anterior belly of the occipito-frontalis beyond these. The orbital branch of the second division of the fifth joins, by its long ascending filaments, with these branches of the facial; so also a perforating filament from the deep temporal of the third division, with others from the auriculo-temporal of the same portion of the fifth, are usually traceable to an union with this nerve. Anteriorly to these are the numerous or- bicular or supra-orbital branches. They pass obliquely forwards and upwards over the malar bone, to supply the orbicularis palpe- brarum, and corrugator supercilii muscles. Their connection with the fifth occurs chiefly by the supra-orbital and lachrymal of the oph- thalmic division ; but others join the malar branch of the second division, where it emerges from its foramen in the malar bone near the outer angle of the orbit. The infra-orbital filaments pass almost hori- zontally forwards from the temporo-facial divi- sion towards the side of the nose. In this course, accompanied by the parotid duct, they cross over the masseter muscle; and more anteriorly, they pass beneath the different muscles which descend to the angle of the mouth and upper lip, and are distributed to them by numerous filaments which enter their deep surface. In this manner the greater and lesser zygomatic, with the proper and common elevator of the lip, and the elevator of the angle of the mouth, receive their ner- vous supply; and the pyramidalis and trans- versalis nasi also obtain filaments from this part of the facial. Many of these, in passing forwards, unite at right angles with the ra- diating bundles of filaments into which the infra-orbital nerve divides after leaving the foramen of the same name. Besides this union with the second division of the fifth, it unites with the ophthalmic by a small twig of its nasal branch, which appears between the lateral cartilage and the nasal bone, and generally by an infra-trochlear filament of the same portion in the angle of the eye. Thebuccal branches, with the same direction as the preceding, occupy a position at a some- what lower level on the face, in the neigh- N \ 2 548 SEVENTH PAIR OF NERVES. bourhood of the transversalis faciei artery. They mostly terminate in the upper half of the orhicularis oris, and in the buccinator, on which muscle they join with the buccal branch of the inferior maxillary division of the fifth. This latter nerve is distributed to the mucous membrane and integuments, and probably has no share in the supply of the muscle. The lower of these buccal branches join another portion of the network, which results from the ramification and union of the next division of the facial. The cervico-facial division^ of smaller size than the temporo-facial, passes do\vn\\ard3 and forwards from the seat of bifurcation of the portio dura, and emerges from the parotid gland near the angle of the lower jaw. Here it divides and subdivides in the same manner as the preceding portion. It is divided into a facial and cervical, or a supra and infra- maxillary part. Its siipra-maxillai't/ part is constituted by one or two large branches, which, breaking up as they pass forwards to the interval be- tween the jaw and mouth, enter beneath the platysma and triangularis menti ; and besides supplying these and the other muscles of this region, they join with a branch of the inferior dental which comes through the mental fora- men. The infra-maxillary ^ or cervical portion of the facial nerve, consists of two or three branches, which, directed still more obhquely downwards, soon divide into very numerous filaments. These pass beneath the platysma to gain the upper and anterior part of the neck, where they form looped ramifications, the most inferior of which are traceable in a vertical direction to a short distance below the hyoid bone. They are chiefly distributed to the platysma, and above they join with the neighbouring supra-maxillary branches just mentioned. They unite beneath the platysma with one, or more usually with two, branches from the superficial cervical nerve of the cer- vical plexus, which turns round the posterior border of the sterno-mastoid muscle to supply the integuments of the same part of the neck. Little can be said with respect to the exact nature of these very numerous junctions of the facial nerve, either with the terminal branches of the various divisions of the fifth, or with the cutaneous nerves of the cervical plexus. They olfer a very obvious anatomical resemblance to that intermingling of different nerves which constitutes a plexus ; but with- out here specifying other distinctions, it may suffice to point out that, in many instances, the branches of the facial seem visibly con- tinued in their previous direction beyond their connections with the fifth. In the absence of more minute investigations, this apparent in- dependence can only be received as indicating a partial involvement of the two nerves, or an incomplete mixture of their fibres, in which one gives to the other, or each gives to each, a small number of its filaments, but retains the large majority. . We next proceed to consider those minuter features in the anatomy of the seventh nerve, which require a more artificial dissection or examination for their verification. The origin of the portio intermedia, rather more externally than the facial, has been al- ready spoken of, and the nerve was then traced to an union, more or less complete, with the neighbouring vestibular portion of the auditory nerve. Beyond this point the views adopted respecting it, from being some- what conflicting, become absolutely discor- dant. The very different nature of the numerous opinions upheld by various anatomists pre- chides the possibility of enumerating them here at full length. Some of these, however, have been already very briefly noticed ; and perhaps, on the whole, the most prevalent was that which supposed the portio intermedia to give a branch which united with the vestibular nerve, while the remaining portion passed itself into the facial. More recently, the anatomy of the distribu- tion and connections of this nerve seems to have been fully made out by Morganti in an elaborate monograph on the Geniculate gang- lion * ; which is, I believe, chiefly known in this country through the medium of an ex- cellent analysis contained in one of Mr. Paget's Reports.-f- By careful dissection of the nerves, which he had previously hardened in nitric acid, Morganti' succeeded in unravelling their filaments ; and thus in separating the portio intermedia from the facial and vestibular nerves to a much greater extent than had hitherto been accomplished. The general result of this process was, that many of the so-called anastomoses were shown to be mere relations of propinquity, due to an intricate entangle- ment, but not implying any real junction or interchange of fibres. In the human subject. — The portio inter- media {fig. 40o, b), shortly after its origin, and 7^-!^. 405. Diagram of the Portio intermedia and its bra7iches. {After Morganti.) * Op. cit. t Eeport on the Progress of Human Anatomv and Ph}-siology in the year 1844-5. British and Foreign Medical Keview. SEVENTH PAIR OF NERVES. 549 while lying closely by the side of the vestibular branch of the auditory nerve (c), gives off a filament (d), which passes towards it. Before joining with it, however, a similarly small branch which comes off from the latter nerve, unites with that previously given from the portio intermedia, and the common trunk thus formed passes into and is lost in the vestibular nerve. The intermediate nerve next emits two small filaments (e), which join the portio dura, and cannot be satisfactorily traced through its trunk. The description is now complicated by the introduction of a large branch of the facial (f) which emerges from it to take a spiral course around the portio intermedia ; and which,, after running with it for some distance, re- turns to the facial at a lower point than that from which it set out. Setting aside this fictitious junction, the whole of the portio intermedia, after the giving off of the facial and auditory branches, was traced into the genuform intumescence : this, it will be recollected, is seated on tlie first bend of the facial in the Fallopian canal, and close to the hiatus of the same name. The nature of this intumescence is the next question to which the description directs itself, and is perhaps even more important than the preceding dissections. The appear- ances of this swelling, and its reddish-grey colour, had long given rise to conjectures of its ganglionic nature. Many anatomists, in- deed, have affirmed its identity with the true ganglions. By others, however, it has been somewhat obscurely described as intermediate in structure between a ganglion and a gangli- form enlargement: a description which can only be understood as indicating their doubt of its ganglionic character, since the supposi- tion of such a gradation of texture is perfectly gratuitous. And others have altogether de- nied its ganglionic characters ; attributing its colour to the minute vessels which pass through the hiatus Fallopii to the facial nerve and internal ear, and explaining the appearance of enlargement or intumescence by the diver- gence of the fibres of the superficial petrosal nerve where it joins the facial. With the question of the ganglionic struc- ture of this body has necessarily been mixed up that of the course taken by the nerves which arise from it, and their relation to the facial. Indeed, the negative side of the ar- gument— the denial of the ganglion — perhaps requires its advocates to explain the real nature of the swelling, and to show the ar- rangement of its supposed constituent nerve- fibres. But in the present day at least, the affirmative of the question may be justifiably reduced to the detection, in the so-called ganglion, of the globular vesicles which are essential to the structure of a nervous centre. it is singular that for a considerable time this simple method of settling the disputed nature of the intumescence should either have escaped notice or failed to afford any satisfac- tory results : the latter seems to have been sometimes the case ; but more frequently, perhaps, this method of proof or disproof was overlooked. The discovery of the ganglion corpuscles, and thus the establishment of its ganglionic nature, belongs to Morganti. He describes it as consisting of meshes or reticu- lations of nerves, the intervals of which are filled by a yellowish ash -coloured substance. In the latter, he states himself to have verified the existence of these bodies. The essential part of this description I am able to confirm. It appears difficult to obtain specimens from the human subject in a state sufficiently fresh to observe these delicate and easily decomposed corpuscles. In the lower animals, however, this difficulty is no longer met with ; and many of them present the additional advantage of a much less dense neurilemma than that which is present in the human structure. After removing the brain of the sheep, the ganglion may thus be easily exposed and removed, preferably with the nerves still attached to it. Cutting off" the attached extremities of these, and very gently and imperfectly tearing up the ganglion which remains, completes the preparation of the specimen. Under these circumstances, the corpuscles of the grey matter are readily visible. They are of an oval or roundish shape, and of a very large size, which amounts in the average to about the 1 -200th of an inch. In the uninjured parts of the specimen, they appear to be disposed with considerable regu- larity, each being in contact with several others by a part of its surface. On a rough calcula- tion, the ganglion contains about three or four hundred of these corpuscles. The contents of the corpuscles are of the ordinary kind. A nucleus occupies some portion of their inner surface, and a large quantity of the usual granular substance fills up the remainder of their interior. Most of them also contain a quantity of pigment towards one extremity of their ovoid cell-cavity. This is disposed as a dark brown mass of an oval form, and some of these masses, when seen isolated by the accidental rupture of their containing vesicles, have exhibited a defined and sharp outline, which induces me to suspect their inclusion in a cell membrane, separating them from the rest of the contents of the vesicle. Rarely there are appearances of short processes from these vesicles. Nerve tubules in rather spar- ing quantity are found in contact with these large cells, mostly occupying their interstices, or coiled around their circumference ; and the periphery of the ganglion itself is surrounded by a kind of layer of them : these appear- ances, however, seem distinctly traceable to the mechanical violence employed in the examination, which forces the tubes into the situations of least pressure ; and one cannot, therefore, regard them as affording the least insight into the mode in which the nerves are arranged with respect to the vesicles. From this ganglion emerge, or rather to it are attached, the following branches : — 1 . and 2. The superficial petrosal nerves, the greater of which (^g. 405, h) passes to the N N 3 550 SEVENTH PAIR OF NERVES. spheno-palatine, and the lesser (i) to the otic ganglion : the first of these Morganti has de- picted receiving a filament which comes from the facial, and in its course to the pe- trosal nerve passes over the ganglion without joining it. The second or lesser of the two appears to be derived solely from the ganglion. 3. A large branch (?«) which forms the great bulk of the chorda tympani ; but, in order to this, is also joined by one or two filaments (n) from the facial nerve, which accompanies it in the Fallopian canal. 4. Branches (/) which passing downwards are lost in the trunk of the portio dura. The annexed diagram, (^g. 405.) with the letters attached to it, will assist the reader in following this otherwise intricate description. It is taken from a drawing by Morganti in the essay referred to ; but it has been reduced in size and simphfied, so as better to allow of its introduction here. The same author has examined into the comparative anatomy of the ganglion and the nerves connected with it in many of the other mammalia, as the dog, calf, lamb, mule, and dormouse. The general results of these examinations abundantly verify his description of the ar- rangement in the human subject. Indeed, these animals offer by far the most favourable subjects for exemplifying the truth of the preceding description, being, as Morganti remarks, natural preparations of these parts. Not only is the dense and intimately adherent sheath of fibrous tissue, which is present in man, much looser in the ganglion and nerves of these animals, but the position of this body with respect to the nerve is considerably altered. The much less marked anterior bend of their portio dura occurs at some little distance from the hiatus Fallopii ; and the ganglion, which is in immediate proximity to this aperture, is thus no longer geniculate in its position, being removed from the knee of the facial. Hence it is, as it were, out of the way of the facial branches, and ceases to be entangled amongst them, as in the human subject. The author of this article can bear testi- mony to the accuracy of these statements; indeed, any one may easily verify them for himself, in most of these animals, with scarcely more trouble than removing the brain and osseous roof of the Fallopian canal, and then stripping off the comparatively lax neuri- lemma from the subjacent ganglion and nerves. The accompanying sketch {fg. 406.) was taken from the left side of a sheep's head. With as little artificial separation as possible, it re()resents the arrangement of the ganglion and nerves in sitfi, especially the manner in which the trunk of the portio intermedia crosses the facial nerve without joining it, and the apposition or proximity, without mingling, of the ganglion and the latter nerve. The varieties of arrangement which obtain in the different animals whose nerves Mor- ganti examined, are chiefly, as might be expected, differences in the degree of inter- lacement of the adjacent nerves. In parti- cular, that of the portio intermedia with the Fig. 406. Auditory, Facial, and Intermediate Xerves o f a Sheep as seen in situ. 3Iagnified about 2^ diameters. a, portio dura ; b, portio intermedia ; c, portio mollis; e, origin of tlie superficial petrosal nerves; /, chorda tympani ; g, geniculate ganglion. vestibular nerve is sometimes so complete and intricate, as to render it in such instances difficult to ascertain from their examination only, whether the former of these nerves gives branches to the latter, or, vice versa, this to that. In the mule, he exhibits a fila- ment from the facial to the ganglion ; but thinks this a possible restitution of one or both of the two previously given to it by the portio intermedia. The general anatomical conclusion to be drawn from these details is, that the facial nerve — as implying in this term both the portio dura and the portio intermedia — arises by two roots. ITpon the smaller of these a ganglion is formed, while the latter is entirely devoid of such a structure. The branches of the facial nerve in the Fallopian canal are mixed nerves, being formed partly by filaments from the ganglion ; partly also by filaments from the aganglionic root ; the latter being in considerably lesser numbers. And the trunk of the facial itself, beyond the ganglion, is also a mixed nerve, since, although by far the greater part of its bulk consists of fibres from the greater root, yet it also con- tains one or two filaments which come from the ganglion. The analogy of this arrange- ment to that of the spinal nerves is sufficiently obvious, and will be hereafter again re- ferred to. It deserves to be mentioned in this place, that many other accounts of the arrangement of these nerves might easily have been added from various authors, but that all of them are more or less at variance, both with the above description by Morganti, and with each other. It has seemed fit, however, to assign these a very subordinate position in the present short article, since the verification of a ganglion belonging exclusively to the portio intermedia includes not only the denial, but I think we may add the disproof, of many of these descriptions. So far as our knowledge of the structure of ganglia at present extends, and whether the late brilliant researches of Ru- dolph Wagner* apply universally or not, we are at least justified in viewing with great * Handworterbuch der Physiologie. Sieben - zehnte Liefermig. Artikel " S^■Tnpathi?cher Xerv Ganglienstniktur und Xervenendigung." SEVENTH PAIR OF NERVES. 551 incredulity any account of the unaltered pas- sage of a nerve through a ganglion, as viewed by the unassisted eye ; and, in the particular instance before us, the microscope disproves this supposition. So, also, concerning the various theories of the derivation of the super- ficial petrosal nerves which have been set forth as based on dissections. Let it be granted that there are two ganglia, — the sphenopalatine and the geniculate, — which are united by an intervening nervous cord : in such a case, I cannot see how any merely anatomical skill would enable one to predicate a definite di- rection as taken by the connecting nerve. Indeed, any statement of this kind really amounts to asserting a special direction or quality of the nervous force, and to the affir- mation or denial of such a view, the scalpel affords no assistance. The unravelling of the nerves themselves, even as performed in the above dissections, requires, perhaps, to be received with con- siderable caution ; and that natural separation or simplification which is afforded by their comparative anatomy must be regarded as vastly increasing the value of the results obtained. The chorda tympani affords a good instance of the conflicting results of these dissections, when unaided by this latter method of inquiry. Some have considered, with H. Cloquet and Longet, that, after remain- ing a short time in contact with the gustatory or lingual branch of the fifth, the whole of this nerve passes away from it, to form one of the roots of the submaxillary ganglion. Others have described it as only giving a fila- ment to this ganglion, and uniting itself by the remainder of its bulk with the branch of the fifth ; while others have failed to detect any direct transition of the chorda tympani into the ganglion, but, on the contrary, have found the two nerves inseparably mixed up below the situation of their visible junction. And more recently it has been traced by Guarini* to the lingualis muscle. On general grounds, the first of these notions is liable to much objection, since it seems singular that a nerve so far removed from the facial as the chorda tympani is at the base of the skull, should be involved in such an accidental proximity as this would make it, or should run so closely to the gustatory without any interchange of fibres. Again, the total pas- sage of the nerve to the ganglion appears very improbable, when the relative size of the entering and emerging branches is considered, — that is, on comparing the bulk of the chorda tympani with that of the two or three filaments which join the ganglion, it may be seen that the former is larger than all of them together. This is especially the case in some of the lower animals, as the dog ; in whom the submaxillary ganglion and its roots from the cerebral nerves are so greatly reduced in size as to be scarcely visible to the naked eye, while the chorda tympani continues a compa- ratively large branch. But these general * Annali di Medicina. Maggio. 1842. objections will not apply to the supposition of a partial connection of the chorda tympani with the submaxillary ganglion, and the ques- tion must accordingly still remain in doubt. Physiology of the seventh nerve. — The func- tions sustained by the auditory nerve are recognised with sufficient certainty. The anatomy of its distribution, its variations in the different classes of the animal kingdom, and the results of experiment or disease affecting its structure, all unite to indicate it as the nerve which, specially adapted at its periphery in the organ of hearing to receive impressions from the vibrations of the ex- ternal air, conveys them to the brain, and by exciting corresponding impressions there, gives rise to the production of a sensation which we term a sound. For the further details of its function, reference is made to the article Hearing. The facial nerve. — It has been seen from the preceding description, that the facial nerve is distributed almost exclusively to muscular structures ; and, although these are very numerous, yet they all admit of being reduced to one class, viz. the muscles of the face. A further subdivision would next sepa- rate them into several groups, which serve to enlarge or diminish the size of the various apertures by which impressions are admitted to the organs of the special senses, as the eye, ear, nose, and tongue. But these ori- fices are also the pathways of food and air, so that the muscles which regulate their size have thus far an influence on the functions of respiration and digestion. In man, they fulfil the further purpose of organs of expres- sion ; their various and complicated adjust- ments conveying, for the most part, a toler- able index of the passions or emotions of the presiding mind. This prominently muscular distribution of the facial would lead us to expect d priori that the nerve was chiefly motor in its func- tion ; and, if we turn from its anatomy in the human subject to its varieties of arrangement and appearance in the animal kingdom, this view will be abundantly confirmed. Not only is its peripheric distribution almost ex- clusively muscular, and in connection with the same facial set of muscles, but it also experiences a development which is co-equal with that of these organs, increasing with their augmented development, or disappear- ing with their suppression. Thus, in Fishes, the facial scarcely exists as a separate nerve. In Reptiles and Birds, its small size corre- sponds with the bony and immobile state of the face. In the Mammalia, it becomes much more considerable, and both the nerve and muscles experience various degrees of aug- mentation. Thus, in the monkeys it attains a large size, in accordance with the number and magnitude of the facial muscles generally ; and the trunk of the elephant, and the mus- cular apparatus connected with the blowholes of Cetaceans, are supplied by large branches from this nerve, which here experiences a partial development, to meet the special exi- 552 SEVENTH PAIR OF NERVES. gencies of the case. In man, the nerve at- tains the maximum of general development. Experiment also confirms the testimony afforded by the human and comparative ana- tomy of the facial nerve : indeed, the results afforded by this method of enquiry first led Sir Charles Bell* to the discovery of its function. On cutting across the trunk of the nerve, he found that the whole side of the face on which it was divided had com- pletely lost the power of movement, while its sensibility remained unimpaired. His experi- ments have since been frequently repeated, and invariably with the same results. The over-excitement of the nerve affords evidence of its motor function, equally with the destruction of its continuity. Thus, gal- vanism of the distal extremity of the cut nerve at once sets up convulsive movements in the nuiscles to which it is distributed. The paralysis produced by section includes all those muscles which the facial has been previously described to supply ; but the muscles of the jaw, which are furnished with nerves from the inferior maxillary division of the fifth, are still free to execute their con- tractions, and hence the movements of the jaw continue. But although these are still carried on, yet the act of mastication as a whole is rendered very imperfect ; since this not only requires the apposition and trituration of the teeth upon each other, but also demands accessory though subordinate movements of the neighbouring lips and cheek, and the section of the facial nerve distributed to these parts render these adjuvant movements im- possible. In such cases an imperfect masti- cation may indeed be seen to take place ; but the cheek and lips, having lost their contrac- tility, instead of pressing in the food towards the teeth, and submitting it again and again to their action, allow it constantly and gra- dually to accumulate in this flaccid and yielding pouch ; or permit it to fall out of the anterior opening in the mouth. In this instance, experiment throws a reflected light upon descriptive anatomy. The buccinator muscle, which forms the greater part of the fleshy parietes of the cheek, was previously mentioned as receiving branches from both the facial and inferior maxillary nerves ; and were we to confide altogether in the appear- ances seen in dissecting these nerves in the human subject f, we might perhaps justifiably regard them as sharing between them the supplying of the muscle. But the {)aralysis of the buccinator, which is always present in those instances where the facial nerve has suffered division, points distinctly enough to the latter as at least taking the more consi- derable and important part of the two ; while * Exposition of the ^^atural System of the Nerves of the Human Body. London, 1824. f The lesser development of the facial muscles of the lower animals allows the distribution of the small buccal nerve to be more easily traced. Thus, in the dog, the two small filaments which form it pass, as is evident on dissection, almost exclusively to the mucous membrane and buccal glands. the failure of the galvanic stimulus to affect the muscle through the buccal nerve, indicates that the filaments of the facial are in all j)robability the only motor nerves which are distributed to it. Many of those cases of paralysed facial nerve, which occur in the human subject as the effect of disease involving their structure, approximate closely to the results obtained by an artificial division of the nerve in animals ; but in consequence of the much more ex- pressive character of the human countenance in the normal state, the deviations produced are even of a more striking appearance. One half of the face forms a perfect blank, its muscles hanging passively from the subjacent structures ; while the movements of the opposite side are distorted by the absence of their proper antagonist motions, and are ex- aggerated in appearance by the contrast. In the experiments above mentioned. Sir Charles Bell found that immediately on di- viding the nerve the muscular aperture of the nostril, which had previously been subject to an alternate dilatation and contraction during the periods of inspiration and expiration respectively, suddenly lost this movement. He has termed the portio dura the respiratory nerve of the face ; since it presides over these and other motions of the facial muscles, which are developed independently of the will, and in answer to the necessities of res- piration. The section of the facial nerve indirectly affects the sense of smell. This fact was also first pointed out by Sir Charles Bell, and has since been confirmed by many other observers. Under these circumstances, the power of discerning strong odors, as tobacco and ammonia, appears to be much diminished on the affected side, although scarcely abso- lutely lost. This loss of smell has been ascribed to the absence of two causes greatly conducive to the exercise of this faculty in health. The muscular contraction of the nostril which accompanied the effort of snuffing effects a considerable narrowing of the aperture ; and in the deep inspiration which accompanies the act, the rapidity of the entering current of air is thus greatly augmented, and in this greater velocity is implied an increased contact of the odorous vapour with the sensitive surface. Besides this, the direction of the current of air seems to be somewhat altered ; the muscles, tending much more to constrict the posterior than the anterior parts of the orifice, appear to direct the current more upwards or anteriorly than in the ordinary inspiration. The me- chanical nature of the action has been illus- trated by Diday *, who has shown that dila- tation of the nostrils by a glass tube, through which the air may be respired, equally pre- vents the perfect exercise of the olfactory sense ; and Longet confirms his experiments. The effect of division of the portio dura on * Gazette Medicale, 1838. Memoire sur les appa- reils musculaires annexe's aux organes des sens. SEVENTH PAIR OF NERVES. 553 the eye is still more important. There is complete inability to close the eyelids of the affected side. This permanently open state is due to the action of the levator palpebrae, unopposed by the paralysed orbicularis pal- pebrarum ; and the eye itself, no longer pre- served from the contact of foreign bodies, or swept over by the conjunctiva which lines the eyelids, is often irritated into inflammation. The hazy vision which accompanies this con- dition is partly attributable to this cause ; but more frequently depends on the im- perfect removal of the lachrymal secretion, which becomes irregularly diffused in a more or less solid or dried state over the globe. The general relaxation of the orbicularis perhaps aids this, and it has also the effect of altering the position of the punctalachrymalia, and thus preventing the natural exit of the secretion, which is sometimes poured down the face. But these effects are on the whole rarely so complete as is above stated ; the aperture between the eyelids is usually small, and movements of the globe of the eye are to some extent substituted for those of the lids ; so that the general results offer the most marked contrast to the rapid disorganization which follows the section of the fifth nerve which forms the sensitive supply of these parts. Besides the influence of the focial nerve on mastication, as shown by the result of its paralysis or artificial division ; the sense of taste appears to be considerably impaired on the corresponding side. This fact has been well illustrated by M. Claude Bernard *, who has collected nine or ten cases of this kind. The manner in which the sense is affected seems to vary. Thus, he describes it as an impairment, in which the most sapid sub- stances failed to excite their ordinary im- pressions, and are only perceived after a considerable interval of time. Professor Roux has left a recital of his sensations during a rheumatic facial hemiplegia ; and in his description, which Longet quotes -}-, he mentions that everything on the affected side tasted strongly metallic ; whence it would appear that this diminution of taste is some- times substituted by a jjerversion or deprava- tion of the function. And M. Bernard has conclusively shown that the chorda tympani is the immediate in- strument of the change. He has adduced instances of paralysis from experiments, in which the facial nerve being divided above the point where this nerve diverges, the taste was constantly impaired ; while in the facial paralysis due to disease of the nerve below its origin, the sense was unaffected. In connexion with these facts may be mentioned the motor function of the chorda tympani. It has been previously stated that, among other courses ascribed to this nerve after its union with the gustatory, Guarini has succeeded in tracing its filaments to the * Archives Generales de la Medicine, 1843, 1844. f Op. cit. torn. 11. p. 405. lingualis muscle. But in addition to this, he has adduced experimental evidence of a much more conclusive character. He found that galvanising the fifth, ninth, and fiicial nerves affected the muscles of the tongue in a very different manner. When the sensitive nerve was stimulated, the tongue remained without movement ; but in the case of the ninth and facial, an upward and downward movement v/as perceptible. When the hypo- glossal was galvanised, a backward and for- ward motion was added to this common movement; while on stimulating the facial nerve, the middle tract of the tongue, which had remained tranquil in the previous experi- ments, was agitated in a vermiform manner. This latter movement was instantly anni- hilated by section of the chorda tympani. The region which it occupied was that of the lingualis muscle, and to it he traced some branches of the nerve : while the upward and downward movement belonged to the stylo- glossus. The cause of the affection of the taste is very imperfectly understood ; since, in the case of the tongue, it seems difficult to con- nect such an impairment of the special sense with any mere loss of motion. Bernard has, however, offered such an explanation ; in which, as a preliminary, he supposes a vermi- form movement like that observed to be ne- cessary to taste, and that it acts by increasing the contact of the papillae of the tongue with the sapid particles. And although this is sufficiently unlikely, yet it is advisable to recollect that, unless guided by experience, we might have asserted the same improba- bility in the instance of smell ; while this sense has been seen to experience an equal impairment, and in a method very similar to this which Bernard has supposed : — viz. by a diminution of effective contact between the object of the special sense and the distribution of its nerve, which contact is itself in part the result of the contractions of certain muscles, supplied by branches of the facial. The mixed nature of the chorda tympani, as laid down by Morganti, may perhaps ex- plain these effects in a different manner; by suggesting that the paralysis of this nerve involves the loss of some of the sentient as well as motor filaments distributed to the tongue. And the varieties in the nature of the affection which were indicated above, per- haps render this explanation a more probable one. A connection has also been traced between the paralysis of the portio dura and an ab- normal state of the soft jmlate : — the curtain of the palate itself being somewhat relaxed, while the uvula is drawn towards the unaf- fected side. In a great number of facial palsies, however, this deviation is absent. But although materials on this point are yet somewhat few, it n)ay be safely stated that its presence or absence varies according to the seat of the disease causing the para- lysis : _ if above the geniculate ganglion, the deviation appears pretty constantly present ; if below, it is absent. The light \vhich ex- 554 SEVENTH PAIR OF NERVES. periment affords is somewhat uncertain and conflicting. Mechanical irritation of the root of the facial nerve in various animals has failed to excite contractions of the muscles of the palate, both with Valentin* and Hein.f The stimulus of galvanism has also acted irregularly and variably, being sometimes fol- lowed by contractions, sometimes not. It is, on the w4iole, difficult to avoid coming to the conclusion that the facial nerve is intimately associated with the movements of the palate by its greater petrosal branch : but the actual transmission of its uninterrupted filaments through the spheno-palatine ganglion is, on anatomical grounds, exceedingly doubtful. And the experiments above mentioned, to- gether with others in which Hein found that its division did not affect pre-existing move- ments from other nervous sources, render the term " motor nerve " clearly an inapplicable name. Concerning the influence of the facial nerve on hearing, little is known at present. Longet, in quoting the above case of M. Roux, in which comparatively faint sounds were painfull}^ distinct, has given a very pro- bable and ingenious explanation of the fact, by pointing the derivation of the nerve to the tensor tympani from the otic ganglion, which is itself associated with the geniculate gan- ghon and facial nerve. Regarding this muscle as the regulator of the acoustic drum, and the tension of this as the means of moderating excessive stimulus, just as the iris does in the eye, he shows the probability that the paralysis of the tensor in this manner de- prives the ear of an important protection, and increases the loudness of the sound received. It has thus been deduced that the facial is chiefly a nerve of motion ; or, in other words, that by its central and peripheral organization it is adapted to determine the contraction of the facial muscles. It has next to be con- sidered whether it is exclusively motor, or whether, on the contrary, it contains a certain proportion of nervous filaments, the office of which is the production o{ sensations. The highly sensitive integument which forms the surface of the face, evidently re- ceives its nervous supply solely from the different divisions of the fifth ; and the anatomy of the distribution of these branches is confirmed by comparing the results which are obtained by artificial section of the facial and fifth nerves. In the case of the divided portio dura, it was previously mentioned, that while motion is lost, sensibility is unaffected ; while in the common instance of the divided fifth, mobility remains, but the sensibility of this surface completely vanishes, and no ex- pression of pain can be obtained even by cauterising large portions of the integuments. The facial is thus excluded from all share in the tactile sensibility of this surface ; yet it by no means follows that the nerve itself is wholly insensible. On the contrary, the ex- * Lehrbuch cler Physiologic, B. ii, S. 673. t Midler's Aichiv. 1844. Heft. 3, 4. periments of most physiologists from the time of Bell agree in verifying the fact of its sensi- bility ; as shown by the expressions of pain which are called forth on mechanically irri- tating the nerve in the living animal. Thus, pinching the trunk of the facial, or any of its larger branches, or the act of section itself, have been constantly found to be accompanied by the most unequivocal indications of sufier- ing. From the evidence above stated, it is mani- fest that the sensory filaments which we must suppose the trunk of the facial to con- tain, are not distributed to the cutaneous surface of the face. But although the skin is the chief organ of common sensation, it is by no means the only seat of the function : a variable but necessary share is possessed by the whole body, and accomplishes the general purpose of protection, perhaps also confers the muscular sense. Thus, by means of sensa- tion, the injury of any particular part deter- mines the occurrence of pain which is referred to that situation ; and in this manner atten- tion is directed to the seat of injury, and its duration or increase is prevented by a voluntary act. And it is probable that the sensitive branches which accompany the portio dura are of this kind ; branches which, although very different in function, travel with the motor nerve, because they experience a distribution in its immediate neighbourhood. Indeed it is perhaps not unlikely that some of the sensory filaments which are included in the facial may bear a protective relation to this important nerve itself, possibly by a virtual distribution among its fibres : — a notion which would thus far approximate to the supposed '* nervi nervorum " of the old authors. But although the sensibility of the facial nerve is well ascertained, the origin or imme- diate cause of this endowment is still a matter of considerable dispute. The numerous views adopted by different authors offer many slighter modifications, but they are all re- ducible to two chief theories. One of these considers that the facial nerve is insensible at its origin from the brain ; and that whatever amount of sensibility it subsequently exhibits is due to foreign filaments, which come from the acknowledged sensitive nerves of the fifth and pneumogastric ; and which, joining the portio dura in different parts of its course, accompany it beyond these points included in its substance. The other regards the facial nerve as arising by two roots, whereof the larger is motor, the smaller sensitive ; and that the sensibility of the nerve as a whole is the result of its double constitution, and is effected by its own sensory filaments. Each of these theories has received the sanction of distinguished anatomists. Thus, amongst many others, the first has obtained the sup[)ort of Magendie, Cruveilhier, Eschricht, Lund, &c. ; while the latter numbers amongst its advocates, Arnold, Bischoff, Goedechens, Barthold, and, more lately, Morganti. The dispute scarcely involves the function SEVENTH PAIR OF NERVES. 555 of the portio dura in that larger sense, in which we generally use this word of nerves ; and hence the changes elFected by disease afford very little aid to the settlement of the question. The inquiry therefore limits itself to a judg- ment on the two remaining kinds of evidence : firstly, the results of experiment ; and secondly, the anatomical appearances. With this latter means of proof, a third is intimately associated in the present instance ; viz. the analogies offered by the structure of the facial to other nerves, of which the functions are better ascertained. These analogies, where present, will argue a similarity of function ; and in a degree of probability varying with the degree of the resemblance. On the supposition that the sensory fila- ments are borrowed from neighbouring nerves, the very numerous junctions of the facial and fifth would naturally point to the latter as constituting one of the most probable and important sources. There are two ways of instituting the question experimentally. If these filaments come from this nerve, the destruction of its continuity will annihilate the sensibility alike of the facial and itself. Again, if the portio dura be insensible until joined by these branches of the fifth, irritation or section of the former nerve, previous to the point of junction, ought to be unattended by pain. In both these methods, the fifth is functionally separated from the facial ; but in the second instance, the natural isolation of this nerve behind the situations where the fifth joins it, supplies the place of the artificial isolation practised in the first. And in both the continuance of sensibility would imply that the portio dura possessed inherent sensi- tive fibres. The division of the fifth nerve within the skull, or close to its origin from the ence- phalon, has been attended with insensibility of the facial, in the hands of Magendie*, Es- chricht, Lund f, and Longetlj: ; and I am not aware of any such experiments which have contradicted their statements. The latter author states that, under these circumstances, the insensibility of the portio dura is perfect ; but Lund and Eschricht, although they seem to deduce the same conclusion that he does, viz. that the sensibility of the facial nerve is entirely due to its anastomoses with the fifth, — yet, nevertheless, distinctly state that in their experiments the insensibility produced extended only from the ear forwards ; while be- hind this situation the portio dura still evinced a well-marked sensibility. Apparently, Longet would explain this contradiction by supposing that the nerve behind the ear, which they found to be still sensible, was an ascending filament of the cervical plexus ; but it seems very unlikely that they should confound the facial trunk with so very small a twig as one of these cervical branches would be. It must * Le9ons sur les Fonctions du Systeme ISTerveux, torn. ii. p. 181. f Dictionnaire des Sciences Medic, Journal Com- plem, torn. xxvi. p. 204. X Loc. cit. be observed that the results afforded by section of the fifth are only valid when the whole of the nerve has been divided, since in any other case there is a possibility that the sensibility of the facial, which remains after the operation, is due to the reception of filaments from the uncut branches. These anatomical considerations apply even more forcibly to the second series of experi- ments. Thus, in some of them, conclusions are sought to be drawn from the observed sensibility of the larger branches of the nerve in the face ; but the numerous anastomoses with the fifth, of which mention has pre- viously been made, and especially that large union with the auriculo-temporal nerve of its third division, immediately in front of the ear, invalidate all these results. Similar contradictory evidence obtains con- cerning the sensibility of the facial at its emergence from the skull, or behind its more visible junctions with the fifth. Thus, Valen- tin regards it as insensible in this place, while the experiments of Longet, Morganti (and probably Eschricht and Lund, as above stated), induce them to maintain the opposite opinion. So that, perhaps, on the whole, the balance of evidence inclines towards the statement that the irritntion of the facial nerve at the stylo-mastoid foramen is attended with expressions of pain, and, therefore, that the nerve is possessed of sensibility at this place. The reception of this fact considerably narrows the question ; since the only branches connected with the facial above this point are, the greater and lesser superficial petrosal nerves, and the auricular filament of the pneu- mogastric. But Morganti has laid bare the chorda tympani in the tympanum, and has proved its sensibility to irritation. And this nerve, it will be recollected, comes* from the portio dura at a point above its junction with the auricular filament; and since the latter is thus not essential to the sensibility of this branch of the facial, so in all probability it is not necessary to the sensibility of this trunk itself. Thus the superficial petrosal nerves only remain ; and many who consider one or both of these to join the facial, explain the sensibility of the nerve in the Fallopian canal by supposing that they convey to it branches of the second or third division of the fifth, which pass through the spheno-palatine and otic ganglia respectively. But, as has been previously stated, anatomy fails to recognise such a direct passage to the facial ; and, on the contrary, by showing the unequivocally ganglionic nature of the genuform intumes- cence, renders it highly improbable. And on physiological grounds, it seems difficult to imagine that a nerve or nerves should pass unchanged through two successive nervous * Some have supposed the chorda t\Tiipani to pass from the gustatory to the facial nerve, con- veying sensitive fibres to it. But numerous argu- ments, especially its anatomy and function as above mentioned, combine to render this sujiposition quite untenable. 556 SHELL. centres, of which they form such large and important roots : while, allowing them to be aflfected in their functions, we are at least not justified in calling them " sensitive branches of the fifth." By this elision of one sensitive anastomosis after another, sensibility still remaining, we have been led, in a retrograde course, to the ganglion at the hiatus Fallopii : at and above this point the evidence afforded by experi- ment fails us. Magendie* states himself to have succeeded, in one instance, in exposing the facial nerve within the skull, or where it enters the auditory meatus ; and adds that it was in- sensible to irritation. But the experiment stands alone, and it appears doubtful whether the portio intermedia was included in the irritation. But the anatomical discoveries of jNlorganti may somewhat supply the deficiency of direct evidence. He has pointed out the complete analogy of the facial to a spinal nerve ; and hence deduces the probability, that the portio intermedia, which exclusively forms the geni- culate ganglion, is, hke the posterior or gan- gliform root of the spinal nerve, the source of sensitive fibres to the compound nerve. The observed insensibility of the facial after section of the fifth militates strongly against this view. But it will be recollected that although affirmed by some, it has been denied by others. And even granting it to be as complete as Longet states it, yet possibly it would constitute a less conclusive objection than might at first appear. For when we consider the violent nervous shock which division of the important trifacial must pro- duce on the parts in the immediate neigh- bourhood of its origin, and the close prox- imity of the two nerves at their roots, w^e are perhaps justified in considering the result an insufficient testimony to their more imme- diate connection. A comparison of the lesion and symptoms in many cases of cerebral hemorrhage would almost parallel the occur- rences of such an anaesthesia ; while, in such an instance, a direct continuity would scarcely be admitted. But even granting that the facial nerve, as thus constituted, possesses an inherent sensibility, it is still probable, from its nu- merous anastomoses, both with the fifth and with the cervical nerves, that it subsequently receives many additional sensory filaments. These junctions differ from a plexus like the cervical, or brachial, in the fact that, in place of forming communications between the mixed nerves of different segments of the body, they connect nerves of different endowments. The exchange appears to be at the expense of the sensitive nerve ; that is, more filaments seem to pass from the fifth to the facial than from the latter to the former. The amount of these filaments given to the different branches of the seventh is said to differ : thus, Longet affirms the insensibility of the " mentonnier," or supra-maxillary portion. * Loc. cit. Little can here be said of the more minute ramifications of Morganti's theory.* But nothing that is known at present, either of the facial generally, or of the chorda tympani, or superficial petrosal branches, is absolutely incompatible with his views. All of these branches, except the lesser petrosal, he shows to be mixed nerves : the experiments and observations above quoted tend to indi- cate all as more or less directly subservient to motion ; and in none are we able to deny the possibility of sensation. But the petrosal nerves would probably be likened to the branches which connect the roots of the spinal nerves to the sympathetic ganglia on the side of the spine ; and the obscure and un- certain results obtained by experiment on these filaments of the facial are closely analogous to the effects of similar experiments on the spinal nerves in connection with the sympathetic of the trunk. But the anomaly of the tensor tympani being apparently supplied solely from the sensitive portion of the facial nerve, is very much weakened by the physiological facts of the involuntary character of its movements, and the interposition of a second ganglion. The more important effects of disease of the facial nerve have already been spoken of in treating of its functions. For its morbid anatomy, in which it offers no especial pecu- liarity, reference is made to the article Nerve. Bibliography. See Xervous System. (^William BrintonJ) SHELL. — This term is commonly emj^tloyed to designate the hard envelopes in which the bodies and members of many animals be- longing to the Radiated, Molluscous, and Articulated sub-kingdoms are enclosed. Ge- nerally speaking, it is applied to those only into whose composition mineral matter enters : thus, we speak of the shell of a Crustacean, whilst we do not give that appellation to the dermo-skeleton of an Insect or Myriapod. Still this rule is not strictly observed ; for there are many Crustacea and Mollusca which are commonly spoken of as possessing shells although these bodies are entirely destitute of calcareous matter, being as horny in their texture as the envelope of a beetle or a centi- pede. Among radiated animals, the class of EcHiNODERMATA is the only one in which shells are met with ; and these are by no means universally present throughout the group. In the molluscous series, we meet with shells in every class save the Tumcata ; all the animals of the class Conchifera, Xhevlamelli-branchiate or pallin-brajicl/iate, being furnished with them ; a considerable propor- tion of Gasteropoda (all of them, it would seem, in the embryonic state) possessing them ; * The comparative anatomy of the geniculate ganglion seems to show that its position is much more closely related to the orifice of the bone than to the motor nerve. Is this any analogy to the similar close relation (to a more external apertiu-e) of the ganglion on the posterior root of a spinal nerve ? C "J SHELL. 55t whilst they are occasionally found in the deli- cate little Pteropoda, and in the compara- tively gigantic Cephalopoda. In this last class, however, the shells are not unfrequently internal; an approach to this arrangement being seen in certain Gasteropoda and Ptero- poda, in which the shells are covered-in by folds of the mantle, whilst really external to :he body. In the articulated series, the pre- sence of a shelly covering, according to the usual acceptation of the term, is more re- stricted. It is possessed by a few Annelida (e. g. Serpula, Spirorbis, &c.), whose shelly tubes so much resemble those of certain Mol- lusks as to be readily confounded with them. It is usually found, too, in the Cirrhopoda, (a class whose articulated character is now quite settled) ; and it is generally present in the Crustacea, although it is only in the larger and more highly developed forms of this class, that the shell is consolidated by mineral deposit, and really deserves the appel- lation. The external configuration of the principal varieties of shelly covering having been suf- ficiently described under the several heads above referred to, it is not requisite here to revert to that subject ; our present purpose being to give an account of the intimate struc- ture of shell, on which an entirely new light has been thrown by raicrosco[)ical en- quiries. The prevalent doctrine respecting the nature of shell, as expressed even by the most recent conchological writers, has been that it is not only extravascular, but completely inorganic^ being composed of an exudation of calcareous particles, cemented together by animal glue. It may now, however, be stated as an ascertained fact, that shell always pos- sesses a more or less distinct organic struc- ture* ; this being in some instances of the cha- racter of that of the epidermis of higher animals, but in others having more resemblance to that of the dermis, or true skin. The nature of the organic structure is so entirely different in the Mollusca, Echinodermata, and Crustacea re- spectively, that a separate description is re- quired for each ; indeed, even in the subor- dinate divisions of these groups very charac- teristic diversities are frequently observable; so that, as in the case of teeth, it is often possible * The idea that such wotild prove to be the case was expressed by the author of this article in the 2d edition of his " Principles of General and Com- parative Physiology" (published in 1841), as fol- lows : — ** The dense calcareous shells of the Mollusca, and the thinner jointed envelopes of the Ciiistacea, have been commonly regarded as mere exudations of stony matter, mixed vrith an animal glue secreted from the membrane which answers to the true skin. The hard axes and sheaths of the Poh-jDifera, hoAv- ever, have been also regarded in the same light ; and yet, as ^yi\l hereafter appear, these are un- questionably formed by the consolidation of what was once living tissue. From the analogy which the shells of Mollusca and Crustacea bear to the epidermic appendages of higher animals, there Avould seem reason to believe that the fonner, like the latter, have their origin in cells, and that these ai-e aftenvards hardened by the deposition of earthy matter in their interior." P. 33. to determine the family, sometimes the genus, and occasionally even the species, from the inspection of a minute fragment of a shell, well fossil as recent; whilst the degree ei^^y^ correspondence or difference in the intimate structure appears to be, in many groups, more valuable than any other single character as a basis for classification, because more indicative of the general organisation of the animal. Examples of both these applications will be presently given. Mollusca. — The shells of Mollusca may always be regarded as epidermic in their cha- racter; being formed upon the surface of the mantle, which answers to the true skin of other animals. As might be anticipated from this description, they are essentially composed of cells, consolidated by a deposit of carhonate of lime in their interior ; but, as in other tissues, we frequently find that the original cellular organisation is obscured by subsequent changes, and we sometimes lose all traces of it. We shall first examine it in what may be consi- dered its typical condition, which is most cha- racteristically seen in certain bivalves. If a small portion be broken away from the thin margin of the shell of any species of Pinna, (this margin being composed of the outer layer only, which projects beyond the inner), and it be placed without any prepa- ration under a low magnifying power, it pre- sents on each of its surfaces, when viewed by transmitted light, very much the appearance of a honeycomb ; whilst at the broken edge it exhibits an aspect which is evidently fibrous to the eye, but which, when examined under the miscroscope with reflected light, resembles that of an assemblage of basaltic columns. The shell is thus seen to be composed of a vast number of prisms, having a tolerably uniform size, and usually presenting an approach to the hexagonal shape. These are arranged perpendicularly (or nearly so) to the surface of the lamina of the shell ; so that its thick- ness is formed by their length, and its two surfaces by their extremities. A more satis- factory view of these prisms is obtained by grinding down a lamina until it possesses a high degree of transparency ; and it is then seen (^g. 407.) that the prisms themselves appear to be composed of a very homogeneous substance, but that they are separated by definite and strongly-marked fines of division. When such a lamina is submitted to the action of dilute acid, so as to dissolve away the carbonate of hme, a tolerably firm and consistent membrane is left, which exhibits the prisn)atic structure just as perfectly as did the original shell (^g. 408.) ; the hexagonal divisions being evidently the walls of cells resembling those of the pith or bark of a plant, in which the cells are fre- quently hexagonal prisms. In very thin natural laminae, the nuclei of the cells can often be plainly distinguished ; but we cannot expect to find these, when the two ends of the cells (at one of which they are generally situated) have been removed by grinding. By making a section of the shell perpendicularly to its surface, we obtain a view of the prisms cut 558 SHELL. in the direction of their length {fig. 409.); and shells, that the decay of the animal membrane it is then seen that whilst many of them pass leaves the contained prisms without any con- Fig, 407. Fic 409. Section of the shell of Pinna parallel to the surface, showing prismatic cellular structure, cut trans- versely. 3Iagnified 185 diameters. continuously from one surface of the layer to the other, some terminate in points midway. _ Fig. 408. Lamina of decalcified membrane of prismatic cellular structure, from shell of Pinna. JIagnifiea loo diameters. Hence it happens that the number of the re- ticulations is smaller on the interior than on the exterior of the layer ; their size, on the contrary, being greater. The 'prisms are seen to be marked by delicate transverse striae, closely resembling those observable on the prisms of the enamel of teeth, to which this kind of shell-structure may be considered as bearing a very close resemblance, except as regards the mineralising ingredient. If a si- milar section be decalcified by dilute acid, the membranous residuum will exhibit the ■walls of the prismatic cells viewed longitudi- nally ; and these will be seen to be more or less regularly marked by the transverse striae just alluded to. It sometimes happens in recent, but still more commonly in fossil Vertical section of prismatic cellular structure, from external layer of shell of Unio occidens. Magnified 40 diameters. necting medium ; and being then quite iso- lated, they can be easily detached from one Fig, 410. Vertical section o f cellular structure of Pinna ; at its lower part the membrane is splitting into thin layers. Magnified 74 diameters. another without any fracture. A group of three such prisms, found in a fragment of chalk, is shown in ^g. 411.: it is seen that these also exhibit transverse stria of a si- milar aspect. By submitting the edges of the membranous walls of the prismatic cells divided longitudinally (as in fg. 410.) to a high magnify ing power, the cause of the transverse SHELL. 559 striation is seen to be a thickening of the cell- wall in those situations ; which will of course jRg. 41L Calcareous prisms of the shell of Pinna ; from Chalk. produce a corresponding series of indentations upon the contained prisms. This thickening seems best accounted for by supposing (as first suggested by Prof. Owen) that each long prismatic cell is made up by the coalescence of a pile of flat epidermic cells, the transverse striation marking their lines of junction ; and this view corresponds well with the fact that the shell-membrane not unfrequently shows a tendency to split into thin laminje along the lines of striation, as shown in the lower part of^g. 410; whilst we occasionally meet with an excessively thin natural lamina, composed of flat pavement-like cells resembling those of the epithelium of serous membrane, lying between the thicker prismatic layers, with one of which it would have probably coalesced but for some accidental cause which pre- served its distinctness. That the entire length of the prism is not formed at once, but that it is progressively lengthened and consolidated at its lower extremity, would appear also from the fact that where the shell presents a deep colour (as in Pinna nigrina) this colour is usually disposed in distinct strata, the outer portion of each layer being the part most deeply tinged, whilst the inner extremities of the prisms are almost colourless. The prismatic arrangement of the carbonate of lime in the shells of Pinna and its allies has been long familiar to conchologists ; but it has been usually regarded as the result of crystallisation. It is now, however, perfectly evident that the calcareous prisms are nothing else than casts of the interior of the prismatic cells ; the form of which, however irregular, they constantly present ; whilst the markings of the membrane are faithfully transferred to the surface of the prism. Further, the prisms in a thick layer of shell frequently present a decided curvature, which would not be the case if their form were due to crystallisa- tion. Not unfrequently, moreover, they are altogether destitute of angular boundaries ; the large quantity of animal matter disposed between the contiguous cells giving them a rounded contour, as seen in Jig. 4-12, and thus causing the calcareous casts of their interior to be cylindrical rather than prismatic. It is only in a few families of Bivalves, how- ever, that the cellular structure is seen in this very distinct form, or that it makes up a large part of the substance of the shell ; and these families are for the most part nearly aUied to Pinna. In all the genera of the MargaritacecB ^ we find the external layer of the shell formed upon this plan, and of considerable thickness ; the internal layer being nacreous. In the Unionidce, on the contrary, nearly the whole thickness of the shell is made up of the inter- nal or nacreous layer j but a uniform stratum Fig. 412. Lamina of outer layer of shell of Ostrea edulis, showing its cellular structure, with a large amount of intercellular substance. Magnified 250 diameters. of prismatic cellular substance is always found between the nacre and the periostracum. In the OstracecB the greater part of the shell is composed of a sub-nacreous substance, the successively-formed laminae of which have very little adhesion to each other ; but every one of these laminaj is bordered at its free edge by a layer of the prismatic cellular substance, distinguished by its brownish-yellow colour : this structure presents itself again in the family PandoridcB, which belongs to quite a different section of the class ; and it is curious to ob- serve that the marked diflTerence in the struc- ture of the shells of Pandora and Lyonsia from that of the Anathiidce and other neighbouring families, harmonises completely with the pecu- . liar combination of characters presented by the animals of these two genera.* In all the foregoing cases, a distinct cellulo-membranous residuum is left after the decalcification of the prismatic substance by dilute acid ; and this is most tenacious and substantial where, as in the MargaritacecB, there is no proper perios- tracum,— as if the horny matter which would have otherwise gone to form this investment had been diffused as an intercellular substance between the proper cell-walls. In many other instances, a cellular arrange- ment is perfectly evident in sections of the shell ; and yet no corresponding structure can be distinctly seen in the delicate membrane left after decalcification. In all such cases, the animal basis bears but a very small propor- tion to the calcareous deposit, and the shell is usually extremely hard. A very characteristic example of this is presented by the outer layers of the shells of the genus Thracia and other Anatinidce. But there are numerous other cases, in which no traces of cellular structure can be detected in the fully-formed shell, and in which we can only be guided by analogy in * See Forbes and Hanlev's British Mollusca, vol. i. pp. 207, 213. 560 SHELL. assigning to them a similar origin with the preceding. We seem justified in doing so, however, by two considerations. In the first place, where the fully-formed shell is destitute of cellular arrangement, this may be frequently detected in the embryonic shell ; as the author is informed by Dr. Leidy of Philadelphia, who has carefully studied the embryology of many Mollusca. And secondly, there are certain shells which exhibit so complete and gradual a transition from a distinct cellular arrangement to an apparently homogenous structure, that we can scarcely doubt the common origin of both substances. This is particularly well seen in the common Mya arenana^ a careful examination of which shell brings to light nu- merous interesting varieties of cellular organ- isation. Thus in J?g.413. we see in one part of Fig. 413. Section of shell of JL/a arenand, s/toiring in one part distinct cellu/ar partitmis, with large nuclear spots ; whilst in another part of the same layer, the celL- houndaries become fainter, and then disappear alto- gether. Magnified 150 diameters. the section a very distinct set of cell-boun- daries, with a large nuclear spot in the centre of each cell ; whilst on the other side we ob- serve that the cell- walls have completely dis- appeared,— the nuclear spots, however, still remaining to mark the cellular origin of the substance. A little further on, these also might disappear, and thus all traces of the original organisation might be lost, though no reasonable doubt could be entertained as to its prior existence. A very curious variety of cell-structure is seen in the large hinge-tooth of Mva, in which there is a layer of large cells occupied by carbonate of lime disposed in a radiated form of crystallisation, resembling that of the mineral called Wavellite. Ap- proaches to this beautiful arrangement may be seen in many other shells. Here, too, we find the partitions between the cells gradually becoming less distinct, as we pass from this peculiar stratum into the surrounding substance, until we lose them altogether. In general, a cel- lular layer may be detected upon the external surface of bivalve shells, where this has been pro- tected by a periostracum,or has been prevented in any other mode from undergoing abrasion : thus it is found occasionally in Ayiomla and Pecten, and generally in Chama, Cleidotlicerus^ Fig. 414. Section of the hinge-tooth of Mya arenaria, showini radiating arrangement of carbonate of lime withir, the cells, and the gradual disappearance of the cell- boundaries, so that the texture becomes homogeneous. 3Iagnified 80 diameters. Trigonia, Anatina, Solen, Glycimeris, Solemya. &c. In the last-named genus it is very firm, and leaves a distinct membranous residuum after the calcareous matter has been removed by acid, which is not the case with the others. The cells of which the outer layer of the shell is made up are frequently rather Jusi/onn than prismatic in their shape, and are disposed with their long axes nearly parallel to its surface, so that their extremities " crop out" very ob- liquely on its exterior, where their rounded terminations, containing nuclei, may often be distinguished when the surflice has not suffered abrasion. (See Jig. 416.) The internal layer of Bivalve shells rarely presents a distinct cellular structure, when examined in a thin section ; and the residuum left after decalcification is usually a distinct but structureless membrane, closely resembling the "basement membrane" of Mr. Bowman. (Mucous Membrane.) This form of shell- substance may consequently be distinguished as membranous. In the Margaritacece and many other families, this internal layer has a na- creous or iridescent lustre, which depends (as Sir D.Brewster has shown*) upon the stria- tion of its surface with a series of grooved lines, which usually run nearly parallel to each other. As these lines are not obliterated by any amount of polishing, it is evident that their presence depends upon something peculiar in the texture of this substance, and not upon any mere superficial arrangement. Wh(in a piece of nacre is carefull}' examined, it be- comes evident that the lines are produced by the cropping-out of laminae of shell situated more or less obliquely to the plane of the sur- face. The greater the dip of these laminae, the closer will their edges be ; whilst the less the angle which they make with the surface, • Phil. Trans. 1814. SHELL. the wider will be the interval between the lines. When the section passes for any dis- tance in the plane of a lamina, no lines will present themselves on that space. And thus the appearance of a section of nacre is such as to have been aptly compared by Sir J. Herschel* to the surface of a smoothed deal board, in which the woody layers are cut per- pendicularly to their surface in one part, and nearly in their plane in another. Sir D. Brewster appears to suppose f that nacre con- sists of a nuiltitude of layers of carbonate of lime alternating with animal membrane; and that the presence of the grooved lines on the most highly-polished surface is due to the wearing away of the edges of the animal la- minae, whilst those of the hard calcareous la- minae stand out. If each line upon the na- creous surface, however, indicate a distinct layer of shell-substance, a very thin section of mother-of-pearl ought to contain many thou- sand laminae, in accordance with the number of lines upon its surface ; these being frequently no more than 1 -7500th of an inch apart. But when the nacre is treated with dilute acid, so as to dissolve its calcareous portion, no such re- petition of membranous layers is to be found : on the contrary, if the piece of nacre be the product of one act of shell-formation, there is but a single layer of membrane. The mem- brane is usually found to present a more or less folded or plaited arrangement ; but this has generally been obviously disturbed by the disengagement of carbonic acid in the act of decalcification, which tends to unfold the plaits. There is one shell, however, — the well-known Haliotis sj^lendens, — which affords us the opportunity of examining the plaits in situ^ and thus presents a clear demonstra- tion of the real structure of nacre. This shell is for the most part made up of a series of plates of animal matter, resembling tortoise- shell in its aspect, alternating with thin layers of nacre ; and if a piece of it be submitted to the action of dilute acid, the calcareous portion of the nacreous layers being dissolved away, the plates of animal matter fall apart, each one carrying with it the membranous residuum of the layer of nacre that was applied to its inner surface. It will usually be found that the nacre- membrane covering some of these horny plates will remain in an undisturbed condition ; and their surfaces then exhibit their iridescent Instre^ although all the calcareous matter has been re- moved from their strzictnre. On looking at the surface with reflected light under a magnifying power of 75 diameters, it is seen to present a series of folds or plaits more or less regular; and the iridescent hues which these exhibit are often of the most gorgeous description. But if the membrane be extended with a pair of needles, these plaits are unfolded, and it covers a much larger surface than before ; and the iridescence is then completely de- stroyed. This experiment, then, demonstrates that the peculiar lineation of the surface of nacre (on which the iridescence undoubtedly * Edinb. Philos. Journ. vol. ii. t Loc. cit. VOL. IV. depends, as first shown by Sir D. Brewster), is due, not to the outcropping of alternate layers of membranous and calcareous matter, but to the disposition of a single membranous layer in folds or plaits, which lie more or less obliquely to the general surface. There are several bivalve shells which pre- sent what may be termed a sub-nacrcot(s struc- ture, their polished surfaces being covered with lines indicative of folds in the basement membrane ; but these folds are destitute of that regularity of arrangement which is neces- sary to produce the iridescent lustre. This is the case, for example, with most of the Pecti- nidce, also with some of the Mylilacecc, and with the common Oijstcr. Where there is no indication of a regular corrugation of the shell-membrane, there is not the least approach to the nacreous aspect ; and this is the case with the internal layer of by far the greater number of shells, the presence of nacre being exceptional, save in a small number of families. The membranous shell-substance, some form of which constitutes the internal layer of most bivalve shells, is occasionally traversed by tubes, which seem to commence from the inner surface of the shell, and to pass towards the exterior. These tubes vary in size from about the l-"20,000th of an inch, or even less, to about the l-2000th ; but their general diameter, in the shells in which they most abound, is about l-4000th of an inch. The direction and distribution of these tubes are extremely various in different genera. Thus, in Anomia Ephippimn they are scantily dis- tributed in the internal nacreous lamina ; but in the yellow outer layer they are very abundant (fg. 415.), forming an irregular net- work, which spreads out in a plane parallel to the surface. In Cleidothcerus chanwides, on the other hand, the tubes are abundant in the internal layer of the nacreous lining, where they form an intricate but irregular net-work parallel to the internal surface of the shell ; and from this arise a series of straight tubes, which pass nearly at right angles with the surface, at a considerable distance from each other, through the external portion of the nacreous layer, towards the cellular structure which constitutes the exterior of the shell. This, however, they do not penetrate; stopping short as they approach it, just as the tubes of dentine cease at its plane of junction with the enamel. The diameter of the tubes is toler- ably uniform, even when they divaricate ; the trunk not being much larger than either of the branches. In other instances, however, no such net-work is formed, l>ut the tubes run at a distance from each other, traversing the shelly layers obliquely, and are then usually of comparatively large size : this is the case, for example, with some species of A7'ca and Pectunculus. That these tubes are not mere channels or excavations in the shell- substance, is proved by the fact that they may be frequently seen very distinctly in the decalcified shell-membrane. They oflen pre- sent, in their beaded aspect, indications of a cellular origin, as if they had been formed o o 562 by the coalescence of a series of cells arranged in a linear direction. They are generally Fig. 415. SHELL. has everywhere a similar origin ; and if one variety of membranous shell-substance be thus Fig. 416. Tubular shell- structure from external surface of Anomia Ephippium. 3Iagnified 250 diameters. most abundant in shells whose exterior has a foliated or sculptured character; and not un- frequently they may be distinctly seen to pass directly towards the prominences of the sur- face, — as in Lima scabva and various species of Chama. They are by no means restricted, however, to shells thus characterised; nor are they universally present in them. Of the oriiiin and mode of formation of the membranous shell-structure, it is rather tliffi- cult to give an exact account. Possibly, alter the epidermic cells have undergone calcifica- tion, so as to form the external cellular layer, the basement membrane itself may become detached from the surface of the mantle, in combination with a la\er of calcareous matter. Even in nacre, however, which may be con- sidered as the most perfect form of this sub- stance, indications of cellular structure are not unfrequently to be seen, especially in univalve shells : these are particularly evident in Ha/ioti<, the nacreous lan,inaB of which, when carefully examined under a sufficiently high magnifying power, are found to be com- posed of minute cells of a long oval form (_y?g. 416.), their short diameter not being above i-oOOOth of an inch. Their boundaries in many parts are very indistinct, or even disappear altogether, so that every gradation can he traced, from the obviously cellular ar- rangement shown in ^g. 412., to the homo- geneous aspect presented by the nacre of bivalve shells. The same cellular structure, and the same gradation to a homogeneous stratum, may be made apparent in the decal- cified membrane ; so that here we seem to have evidence that even the membranous shell- substance is originally formed by the agenc\' of cells, although the boundaries of these have usually been subsequently obliterated, so that the structure comes to present a homoge- neous aspect. Indications of the same cel- lular organisation may be detected in the na- creous lining of the shell in Turbo and Xautilns, We seem justified in concluding that nacre C 0 (I Cellular structure of nacre of Haliotis splendens : the cells cut transversely at a, longitudiually at b, and slio^ving their terminations (viith. nuclear spots) at c. Magnified 450 diameters. proved to have been formed by the agency of cells, little doubt can be entertained as to the corresponding organisation of others. The fact may probably be, that, as maintained by Professor Goodsir the basement mem- brane is itself composed of cells more or less perfectly developed, the boundaries of which usually disappear. Of this view a very good illustration is afforded by the va- rious examples of shell-membrane ; w hich pre- sent every gradation, from the most per- fectly homogeneous pellicle, to a distinct stra- tum of cells. The loss of the original boundaries of the cells, and the consequent obscuration of the real nature of the structure, are by no means peculiar to shell ; for the physiologist is familiar with this change as occurring in various other tissues. Thus, in dentine, the cases in which the vestiges of the original cells are preserved are few in proportion to those in which they are obliterated ; and yet these isolated examples are sufficient to mark the real nature of the transformation of the soft dentinal pulp into the dense ivory. It would seem as if, in the process of calcifica- tion, the cell-walls have a tendency to hquefy or dissolve away, unless supported b}- addi- tional deposits of animal matter, thus allow- ing the complete fusion of their contents. The peculiar tenacity of the decalcified shell- substance in the Margarilaceoe and certain other tribes seems due, not so much to the strength of the original cell-walls, as to the interposition of an intercellular substance between them. In Pcrna we not unfre- quently find, between the calcified layers, membranous laminre consisting chiefly of horny matter interposed between rounded cells that are more or less widely separated from each other : here the animal substance * Anatomical and Pathological Observations, p. 3, note. would seem to be peculiarly abundant, being apparently of the same kind as that of which the byssus of these animals is composed. The ordinary account of the mode of growth of the shells of Bivalve Mollusca, — that they are progressively enlarged by the deposition of new laminaj, each of which is in contact with the internal surface of the preceding, and extends beyond it, — does not express the SHELL. whol 563 truth ; for it takes no account of the fact that most shells are composed of two layers of very different texture, and does not specify whether both these layers are thus formed by the entire surface of the mantle whenever the shell has to be extended, or whether only one is produced. An examina- tion of Jig. 417. will clearly show the mode in w^iich the operation is effected. Tliis figure Ficr. 417. Vertical section of shell of Unto occidens, near the U and tlie internal or nacreous layers : a a', hV, cd, Magnified 8 diameters. represents a section of one of the valves of Unio occidens, taken perpendicul^rly to its surface, and passing from the margin (at the right hand of the figure) towards the umbo (which would be at some distance beyond the left). This section brings into view the two substances of which the shell is composed ; traversing the outer or prismatic layer in the direction of the length of its cells, and passing through the nacreous lining, which is seen to be made up of numerous laminae, separated by the lines aa\ bl/, cc\ &c. These lines evidently indicate the successive formations of this layer ; and it may be easily shown, by tracing them towards the umbo on the one side, and towards the margin on the other, that at every enlargement of the shell its whole interior is lined by a new nacreous lamina, in immediate contact with that which preceded it. The number of such laminae, therefore, in the oldest part of the shell, in- dicates the number of enlargements which it has undergone. The outer or prismatic layer of the growing shell, on the other hand, is only formed where the new structure projects be- yond the margin of the old ; and thus v/e do not find one layer of it overlapping another, except at the lines of junction of two distinct formations. When the shell has attained its full dimensions, however, new laminae of both layers still continue to be added ; and thus the lip becomes thickened by successive for- mations of prismatic structure, each being applied to the inner surface of the preceding, instead of to its free margin. The same ar- rangement may be w^ell seen in the Oyster; with this difference, that the successive layers have but a comparatively slight adhesion to each other. The shells of Terchraiulcc, and of several ), showing the arrangemtnt of the outej or prismatic, successive lines of growth ; d, margin of the valve other genera of Brarhiopoda., or Pa.ll'iobran' chiate Bivalves, are distinguished by peculiari- ties of structure, which serve to distinguish them from all others. When thin sections of them are microscopically examined, they present a very peculiar texture, {fg. 418. a.) FiiT. 418. a b Portion of the shell of Terebratula australis, shoicing the orifices of the perforations, and the peculiar structure of the shell : at a the shell is traversed by the section ; at i is sho-svn its internal surface. which might be referred either to long flattened cells, or to plications in the shell-membrane ; on the other hand, the natural internal surface of these shells always exhibits an imbricated aspect of great regularity (b). If the section pass very obliquely towards this surface, it becomes evident that these imbrications are formed by the outcrop of the long flattened cells or folds, which were seen when the plane of the section has passed in the direction of o o 2 564 SHELL. their length. A great variety of appearances is presented by this structure, according to the direction in which it happens to be tra- versed b}' the section ; but they are all in- dicative of its peculiar character, which is readily recognisable even in the minutest fragment, although its nature yet remains doubtful. The cells, if cells they be, must be excessively flattened ; and no vestige of them can be traced in the decalcified shell ; whilst, on the other hand, the membranous residuum does not give any distinct indication of having been plicated with the regularity necessary to produce such a remarkable appearance. When any recent species of Terebratula is examined, save Ter. psittacea (which is now generally excluded from the genus on other grounds), an additional peculiarity is observed ; con- sisting of the presence of a large number of perforations in the shell, generally passing obliquely from one surface to the other, and terminating internally by an open orifice (fg. 418.), whilst on the exterior they are covered in by the periostracum. Their diameter, which is greatest towards the external surface, varies in different species from about l-1800th to 1 -500th of an inch ; and there is a con- siderable difference, also, in their degree of proximity to each other. In some fossil spe- cies, as Ter, bul'ata, the interval between the passages is scarcely greater than the diameter of the passages themselves. When a portion of one of these shells, which has been pre- served with the animal in spirit, has been completely decalcified by the action of dilute acid, the membranous residuum presents a very remarkable structure, no vestige of which is seen in the ordinary bivalves. Attached to the membranous films are a series of tubular appendages, corresponding in diameter to the perforations of the shell, and arranged at the same distances {fg. 419.): the free extremi- Fig. 4 1 9. Dccalcifitd incinbniiic (>l s/i' /l of J cu LrdtiihL auAiraliy, showing the ceecul tuhtdi, icliirli oevupy tltc jKrfoni- tions of the shell: the tuUuli are Jilted icilli minute cells. Magnified 150 diameters. ties of these appendages have distinct coecal terminations ; and when a sufficient magnif\- ing power is employed, it is found that their contents are distinctly cellular, resembling the cells in the interior of glandular follicles. These ccecal tubuli he in the perforations of the shell, and open on its inner surface ; but there does not appear to be any system of tubes or canals for collecting the matter poured out from them, each coecum having its distinct and independent termination on the internal surface of the shell. The surface of the mantle in contact with the shell is found to be studded with minute cells, cor- responding in size and aspect with those con- tained in the ccecal tubuli. The physiological purpose of this curious structure is at present a mystery ; but there can be little doubt that it is a very important one in the economy of the animal, when we see the shell thus ren- dered subservient to the special protection of the coecal appendages. The perforations are wanting in a large proportion of the very numerous species of fossil TerehralulcB ; and there would appear strong reason for regard- ing their presence or absence as a character of fundamental importance in the subdivision of this important genus.* In most of the non • perforated species, the shell is readily divisible into thin micaceous plates, which exhibit the characteristic texture of the shell in great perfection ; and as this texture undergoes remarkably little change in the act of fossil- isation,it is often possible to recognise a Tere- bratula from a very minute fragment, imbedded even in the palaeozoic strata. A very similar structure exists in several genera allied to Terebratula ; and in some of these, also, as Orth'is and Spinfer, the distinction has to be established between the perforated and non- perforated species ; w hilst in Atri/pa (to which the recent Ter. psittacea pro})erly belongs), all the species are destitute of perforations. There is not, by any means, the same amount of diver.rity in the structure of the shell in the class of Gasteropoda^ as that which exists among the several tribes of Conchifera ; a certain typical plan of con- struction being common to by far the greater number of them. The small proportion of animal matter contained in most of these shells is a very marked feature in their cha- racter ; and it serves to render other features indistinct, since the residuum left after the removal of the calcareous matter is usuall}- so imperfect, as to give no clue whatever to the explanation of the appearances shown by sec- tions. Nevertheless, the structure of these shells is by no means homogeneous, but al- ways exhibits indications, more or less clear, of an original organic arrangement. The porcellanous shells, as formerly stated (vol. ii. p. 381), are composed of three layers, all pre- senting the same kind of structure, but each differing from the others in the mode in which this is arranged. This structure was de- scribed by Mr. Gra} -j- as the result of rhom- boidal crystallisation ; each layer being com- * See a Paper on the Subdhision of the Genus Terehraftda, by ]Mr. J. 3Iorris, in the Journal of the Geoloijical Society, vol. ii. p. 382. t Phil. Trans. 1833, p. 790. SHELL. 565 posed of thin laminae placed side by side, which separate from one another in the planes of cleavage when the shell is fractured. As first pointed out, however, by Mr. Bowerbank, each of these laminae really consists of a series of cells in close apposition ; and the plates are disposed alternately in contrary directions, so that each series of cells intersects the one beneath it nearly at right angles, as seen in j^g. 420. Although the intimate structure of Fig. 420. 07'tion of fractured surface of middle layer of Cyprcta mauritiana, shoiving laniince composed of prismatic cells obliquely crossing one another. MagnifiQd 235 diameters. (After Bowerbank.) each of the three layers of the shell is essen- tially the same, yet the disposition of the laminae is not the same in any two adjoining ones, — an arrangement which adds greatly to the strength of the shell. The planes of the laminae are always as nearly as possible either parallel or at right angles to the lines of growth ; those of the inner and outer layers always having the same direction with each other, but those of the middle layer being set at right angles to them. When, therefore, a section is made parallel to the surface of the shell, it will cut the edges of the laminae of which the layers traversed by it are composed ; but if the section be made in a direction per- pendicular to the surface, and pass through the middle layer in the plmie of its laminae, it will cut through the edges of the laminae making up the interior and exterior layers ; whilst if the section traverse the two latter in the plane of their laminae, it will cut across the laminae of the middle layer. The principal departures from this plan of structure are seen in Patella, Chiton, Ha- liotis, and Turbo and its allies. In Patella, the inner and outer layers are composed of large and irregular laminae, by no means firmly adherent to one another ; but the middle layer is made up of tolerably regular polygonal cells, which form only a thin stratum in some parts, whilst in others they are elongated into prismatic cells ; and the directions of the laminae, of which the inner and outer layers are composed, instead of being conformable with each other, are at right angles. In Chiton^ the external layer, which seems to be of a delicate fibrous tex- ture, but which is of extreme density, is per- forated by large canals, which pass down obliquely into its substance, without pene- trating, however, as far the middle layer. The middle layer, as in Patella, is distinctly cellular ; whilst the internal has the same nearly-homogeneous texture as the external, but shows no trace of perforations. The peculiarities of structure presented by Ha- llotis have been already described. In Turbo and its allies, the inner layer is nacreous, and the middle one is made up of large cells : the cellular structure is also very evident in the solid operculum of Turbo, when reduced to sufficient thinness. That the shell-substance in Gasteropoda is formed in the first instance by the agency of cells, however indistinct their traces may subsequently become, is further apparent from the researches of Mr. Bowerbank on the growth of the shell of the common garden-snail (/7tV2.r aspersa); and his obser- vations further confirm the opinion already expressed, that the formation of each layer of shell is a progressive operation ; new matter being added to its interior after the exterior has been consolidated. Passing by the Ptero])oda, whose delicate membranous shells present no very distinct structure, we come to the testaceous Cephalo- poda, of which there are but few species now existing. The shell of Nautilus pompilius bears more resemblance to that of bivalves in its intimate structure, than to that of the Gasteropodous univalves ; the three layers of perpendicular laminae, so characteristic of the latter, not making their appearance here; and of the two la} ers of which the shell is com- posed, the inner one being nacreous, whilst the outer one is made up of an aggregation of cells of various sizes, those which are nearest the external surface being generally the largest. In the thin shell of Argonauta^ the same kind of irregular cellular structure can be easily distinguished, as in the outer layer of the shell of Nautilus ; but there would seem to be nothing comparable to the inner layer of the latter. The shell of Spi- rula must be cons dered to bear a greater re- semblance, as regards its relation to the ani- mal, to the Sepiostaire of the Cuttle-fish, than to the chambered shell of the Nautilus : although it so closely approximates the latter in its own conformation. This being the case, it is interesting to find that the intimate structure of the shell has a much greater resemblance to the Sepiostaire than would be supposed from its general aspect. For al- though its texture seems uniform, and its minute parts are composed of an aggregation of calcified cells, yet its surface is marked by sinuous lines, closely resembling those which are seen upon the transverse plates of the Sepiostaire ; and these lines or bands project in such a degree, that they might be con- sidered as rudiments of the vertical partitions o o 3 566 SHELL. which connect these plates. The Sepiostaire having been formerly described in some detail (vol. i., \>. o4G), it will only be re- qui-^ite here to mention, that the calcified layers which alternate with horny membranes to form the shallow cone or cup, exhibit a distinct cellular structure, when the section is made sufficiently thin ; and that indications of a similar structure may also be perceived in the delicate and fragile plates which are arranged obliquely upon one another in the hollow of this cup. Few of the numerous fossil shells referable to this cla»s have yet been examined ; it may, however, be stated as an interesting result of microscoj)ic ob- servation, that the " spathose guard" of the Belenmite is thereby proved to be composed of long prismatic cells, radiating from the centre to the circumference; closely re- sembling in their general arrangement those of the massive tube of SejJtaria giganiea, the great sand-boring Teredo of Sumatra. The structure of the shells of the testa- ceous Annelida, and of the pedunculate Cirrho- jyodn, does not essentially diifer from that of MoUusca ; but in most of the sessile Cir- rhopods, such as the common Balamis, we find a cancellated structure or diploe in- tervening between the inner and outer plates of the shell (vol. i., p. 685). A less regular Fig. 421. Cancellated structure from shell o f Hippurite, as seen in transverse section, 3IagniJied 5 diameters. diploe has been described by Mr. J. E. Gray* as existing between the laminae of Oslrea pzirpurea ; but in no other shells of existing Moliusca has any approach to it been yet discovered. A very regular cancellated structure, however, is exhibited in the singular extinct group of Rudisles, where it makes up nearly the entire thickness of the shell {fg. 421.). The cancelli are usually short hexa- gonal prisms, terminated at each end by a flat partition ; consequently, a section taken in one direction (/g. 421.) will exhibit the walls of the chambers disposed in a hexagonal net- work ; whilst a section that passes at right angles to this will bring into view the trans- * :.L-:gaziue of Zoolf>gy and Lotar.v, vol. ii. p. 228. verse partitions ( fg. 422.). The cancelli are frequently occupied by calcareous infiltra- Fig. 422. Cancellated structure from the shell o f Hippurite, as seen in vertical section. Magnified 5 diameters tion ; which nvght lead to the belief that, like the cells of the Pinna, they were so consolidated in the hving state. But they are also to be met with entirely empty, or with their walls merely lined by calcareous crystals ; so that there can be no doubt that they were originally hollow. The presence of this structure assists in determining the zoological position of the curious group in question, which many considerations would lead us to regard as having been interme- diate between the Bivalve Moliusca and the sessile Cirrhopoda. And it may be added that, by the same evidence, the place of the curious Pleiirorhynciis hiberniciis, a fossil which has been assigned to a different tribe by almost every naturalist who has examined it, would unhesitatingly be determined as amongst the Rudistes. Echinodernmta. — The structure of the skeleton in this class is entirely different from that which v.e have fount! to be cha- racteristic of the Moliusca ; whilst, in its essential features, it presents a remarkable uniformity throughout the various members of the group. The general arrangement of its components is the same, for example, in the firm plates which make up the testa of the Echinida, in the joints of the stems and branches of the Criuoiden, and in the scattered calcareous deposits wliich are met with in the integuments and in the tentacula of the Holo- ihnrida. The elementary structure of the skeleton of the Echinodermata may be described as a net-work^ composed of calcareous and animal matter intimately united ; the former, however, being greatly predominat)t. In this net-work, the interspaces or areolents an ovoid outline, the larger end below, and the smaller above. A vertical line falling upon the axillary margin of the scapula di- vides this articular cavity into two unequal portions, of which the inner is the larger. This arrangement in some degree dimini'^hes the tendency to displacement inwards of the head of the humerus, to which, for other reasons, the joint is strongly disposed. An "arrest of development" may cause a deficiency of either the outer or the inner lip of the glenoid cavity, resulting in a congenital dislocation of the head of the humerus, in- wards or outwards, according to the portion of the cavity which is deficient. These con- stitute the " sub-acromial" and " sub-cora- coid " dislocations described by Dr. R. Smith.* Boyer supposes that a deficient develop- * Dublin Journal of IMedical Science, vol. xv , 1839. (Normal Anatomy). o73 ment of the outer lip of the glenoid cavity must pre-exist, in order to permit the dislo- cation backwards on the dorsum of the sca- pula to occur.* A little external to its apex, a slight notch in the margin of the glenoid cavity marks the place of attachment of the long ttndon of the biceps; whilst on its upper and inner side a shallow groove points out the passage of the tendon of the subscapularis muscle. The head of the humerus presents a convex hemispherical surface, the a^pect of which is upwards, backwards, and inwards. An irre- gular wavy line separates the head from the anatomical neck of the bone, the latter inter- vening between the head and the tuberosities. The line which marks the union of the upper epiphysis with the shaft of the humerus has been "long incorrectly described, as though it were identical with the anatomical neck. The upper epiphysis comprises not only the head of the bone, bid also the tuberosities; for though, doubtless, the line of junction between the upper epiphysis and the shalt corresponds internally to the anatomical neck immediately beneath the cartilage of incrustation, yet from this its direction is chiefly outwards, so that externally it passes below the greater and the lesser tuberosities, traversing the bicipital groove which is included between them. This anatomical fact, and the practical in- ferences derivable from it, have been clearly pointed out by Dr. R. Smith.f 2. Structures luhich facilitate motion in the Joint. — a. The border of the glenoid cavity has attached to it a fibro-cartilaginous rim (glenoid ligament) by which the depth of the cavity is somewhat mcreased. This structure is thickest at its attachment to the bone ; its fi ee edge is very thin ; a section of it made at right angles to the bone gives it a triangular outline. Both its surfaces are fined by sy- novial n)embrane, which consequently sepa- rates it externully from the capsular ligament ; superiorly, many fibres of the biceps tendon become continuous with the fibrous portion of the so-called "glenoid ligament," and after prolonged maceration the tendon w ill separate from the bone along with this structure, but to describe the glenoid ligament as formed by the splitting of the tendon of the biceps, would be erroneous. The glenoid ligament is subservient to the following purposes: it deepens the shallow glenoid cavity, and so lessens the liability to dislocation ; it prevents the bony surfaces of the neck of the humerus, and the edge of the glenoid cavity, from being unduly pressed against each other in the ex- tensive motions of the joint ; and it gives a more extended, and therefore a more secure attachment to the tendon of the biceps. b. The articular surfaces are invested with cartilage of incrustation, which, in accordance with a very general rule, is much thicker at the centre ot the convex head of the humerus * Traite' des Malaclies Chirurcricales, torn. iv. p. 176. => ' 1 t Essay on Fractures, &c., p. 203. Dublin, 18i8. 674 SHOULDER JOINT — (Normal Anatomy). than at the circumference; whilst the reverse is true of the glenoid cavity, the cartilage heing there of greater depth at the cii cuiu- ference than at the centre. Theaniitomicaldisposition of (c.) the si/novial v^embrane, can be more conveniently studied after the ligaments have been examined. 3. Comiecting 2Iedici. Capsular I'gament. — This is a fibrous expansion which in itsgenerai character resembles the capsular hgament of other articulations. The capsule of the shoulder joint is remarkable for its capaciousness, and consequent laxity — an arrangement w hich per- mits the great freedom of motion enjoyed by this articulation. It embraces the margin of the glenoid cavit}' above, and is prolonged upon the tuberosities of the humerus interiorly; hence it may be described as a sac having tw o apertures, of which the lower is by fiar the lar;i:er. Viewed externally, its form is that of a hollow cone, the base of which is placed inferiorly. The fibres which compose the capsule are extremely irregular in direction, nor are they of uniform strength or thickness. The capsule is very thin, posteriorly and also internally ; in the latter direction, it is almost aways deficient, so that the cavity of the joint is continuous with that of the synovial bursa, beneath the tendon of the subscapularis muscle ; more rarely, an opening in the cap- sule establishes a communication between the serous cavity of the shoulder joint and a bursa under the infra-spinatns muscle. The capsule possesses considerable strength an- teriorly and above, being there reintbrced by a thick bundle of fibres, sometinies described as a distinct ligament, under the name of coraco-humeral, or accessory/. These fibres are attached superiorly to the under surface of the coracoid process, they thence follow an oblique course downwards and outwards, be- come incorporated with the pro[)er fibres of the capsule, ai:d are traceable inferiorly to the great tuberosity of the humerus, crossing an- terior to its bicipital groove. Infei'iorly, or towards the region of the axilla, the capsule possesses much intrinsic strength, though here totally devoid of any muscular or tendinous coverings. When the arm is nuich abducted, the head of the humerus presses strongly against this part of the ligament, which some- times gives way, and the head of the bone escaping from the glenoid cavity, between the subscapular muscle, and the long head of the triceps, dislocation into the axilla is produced. In this accident, the head of the humerus generally detaches the subscapular muscle Irom the bone, and lies between that muscle and the subscapular fossa. The anatomist will not fail to observe that the subscapular nerve, as it runs from the brachial plexus outwards, to wind round the neck of the humerus, is closely related to this portion of the capsule wdiich may be seen from the axilla, between the triceps and subsca- pularis muscles ; and can, therefore, easily understand why the nerve in question should be sometimes torn or compressed, when the head of the hmuerus has been dislocated downwards and inwards ; this complication of the axillary dislocation gives rise to para- lysis of the deltoid muscle, partial or com- plete, temporary or permanent, according to the degree of injury which the nerve may have sustained. The exterior of the capsular ligament is in close relation SKperiorlij w ith thesupra-spinatus, and jwsferior/i/ with the infra-spinatus and teres minor muscles ; inferiorly^ it is con- nected w ith the scapulai' origin (long head) of the triceps; whilst a?//6';vor(//, it is covered and partly replaced by the subscapularis. With the intervention of the capsular muscles, it is also related on its external, anterior, and posterior aspects to the deltoid muscle, and above to the coraco-acromial triangle. A large bursa is situated beneath the deltoid, and separates this muscle from the exterior of the capsule ; it also gives an extensive in- vestment to the tendons of the capsular muscles, and is evidently designed to favour the very free moti. ns which those parts enjoy. The long tendon of the biceps, placed ex- actly upon the anterior aspect of the bone, escapes from beneath the lower edge of the capsule, which here arches across the bicipital groove, and converts it into a canal ; the capsule is not therefore perforated by the tendon of the biceps, as is stated by many anatomists. A portion of the synovial mem- brane descends with the tendon below the edge of the capsule, is again reflected on the groove, and so re-ascends into the joint, having formed a small " cul-de-sac," without the ar- ticulation. From these relations with the surrounding muscles, the capsule derives nuich of its strength : the tendons of the four capsular muscles are inseparably united to the fibres of the ligament, which are prolonged inferiorly, as far as the lowest portion of the humeral tuberosities; posteriorly, it derives some fibres from the triceps ; and Irom the upper edge of the tendon of the great pectoral nuiscle, (at its insertion into the anterior lip of the bi- cipital groove,) a fibrous fasciculus ascends, and likewise becomes identified with the cap- sule ; this prolongation has been described, under the name of " suspensory frccnum," by Win slow. It must be obvious from this description, that tlie capsular ligament alone cannot maintain the bones of the shoulder joint in opposition: from its great laxity, it permits a considerable separation of the osseous sur- faces, and they are maintained in contact with each other nsainly by the tonic contraction of the surroundmg muscles (w hich are placed in the most favourable position to accomplish this important object). Accordingly, in para- lysis of the ui)per extremity, the limb be- coming elongated, one or two fingers can be pressed into the joint towards the glenoid cavity, now abandoned by the head of the humerus ; and, ow ing probably to a some- what similar condition of parts, spontaneous dislocation of the humerus has been known to occur in the debiUtated state of the sys- SHOULDER JOINT — (Normal Anatomy). .575 tern consequent on the administration of mercury. Neither must the influence of at- mospheric pressure be forgotten, which, ex- erting as it does a force of nearly fifteen pounds on the square inch, must powerfully contribute to preserve the contact of the articular surfaces. Within the capsular ligament, and at the upper and outer part of the joint, two struc- tures are found, which may, with propriety, be described as inter-articular ligaments; these are the tendon of the long head of the biceps, and the gleno-humeral, or Flood's ligament. The long tendon of the biceps has been de- scribed already, as attached to the apex of the glenoid cavity, and to the fibrous portion of its circumferential fibro-cartilage. Surrounded by synovial membrane, it passes downwards and outwards, forming an arch over the head of the humerus, it then descends in the bi- cipital groove, where it is retained in situ by the fibres of the capsular, and of the accessory (^coraco-lunneral) ligaments. Cruveilhier mentions that in two cases he found this tendon united by a strong adhesion to its groove, *' thus justifying the name of * inter-articular ligament:' the tendon for the long head of the biceps took its origin from the same groove." This condition, Cruveil- hier supposes to have been the result of in- jury; but as the appearance in question has been seen by the writer, as the result of chronic rheumatism, affecting the scapulo- humeral articulation, he is compelled, although reluctantly, to dissent from such high autho- rity, and to express his opinion that this change originated in rheumatism, not in ac- cident; his opinion is farther borne out by the state of the inter-articular portion of the tendon in Cruveilhier's cases, for it is stated, that " the bicipital groove was depressed, and the inter-articular ligament flattened, and, as it were, lacerated." The inter-articular portion of the tendon of the biceps, by itself, could scarcely protect the head of the humerus from displacement upwards, a use very commonly assigned to it, as the smooth convex head of the bone would readily slip from beneath it ; but in the interior of the joint, a second band, the " gleno-humeral ligament," cjescribed by the late Dr. V. Flood, is thrown across the head of the humerus, and may contribute to oppose this luxation ; we quote the following de- scription of this ligament from Dr. Flood : — " It may be easily exposed," he says, " by cut- ting through the inferior part of the capsule transversely, and throwing back the arm over the head, you thus expose the interior of the upper part of the capsule, also the biceps tendon. Parallel to the inner edge of the latter, this ligament may be felt and exposed by a little dissection. The tendon of the sub- scapularis in passing to its insertion, rests in a notch in the superior and internal part of the edge of the cavity ; from the edges of this notch, the ligament arises broad and flat, then proceeds along the internal edge of the biceps tendon, and becoming smaller and rounder, is inserted into a distinct pit in the anatomical neck of the humerus, at the inner edge of the bicipital groove. In its triangular form, its origin at a notch in the articular fossa, and its insertion into a jjit, it strongly resembles the ' ligamentum teres ' of the hip- joint."* In nearly all the specimens examined by the writer, the upper half of this ligament had both its surfaces invested by the synovial membrane. This enables the dissector readily to distinguish it from the capsule ; but in- feriorly, its fibres are generally identified with this structure, and therefore it loses the ap- pearance of a distinct ligament, before ar- riving at the humerus. With the mode of its origin, and its intra- capsular position, all resemblance between this structure and the "ligamentum teres" in the hip-joint, ceases ; the latter has little of the structure, and fulfils none of the uses of a ligament. Not so the " gleno-humeral liga- ment:" its structure is distinctly fibrous, it possesses great powers of resistance, and it is an auxiliary to the tendon of the biceps, so that both together are enabled to restrain the undue ascent of the humerus ; an object which it seems probable neither of them could ac- complish, unaided by the other. Si/novial membrane. — In its arrangement and general characters, the synovial membrane of the shoulder joint differs in no way from that of other articulations. As the fibrous capsule is lax, so the serous membrane, which lines it, presents a cavity of large size. Hav- ing covered the articular cartilage of the head, it passes downwards on the neck and tubero- sities of the humerus, as far as the lower attachment of the capsule, to the inner surface of which it is thence reflected : having fined the capsule, the s} novial membrane arrives at the glenoid cavity, the articular surface of which it similarly invests ; it forms sheaths for the inter-articular ligaments, for the long tendon of the biceps, and for the gleno- humeral ligament : that for the former, as has been already described, extends along the bicipital groove, even be\'ond the limits of the capsule. Internally, where the capsule is deficient, the synovial membrane covers the corresponding portion of the tendon of the subscapularis, and here a communication is established between the cavity of the serous membrane of the articulation and that of the bursa mucosa, which is found beneath that muscle. A similar communication sometimes exists posteriorly between the cavity of the joint and the bursa, which is subjacent to the infra-spinatus muscle. A few fatty folds are generally found attached to the reflections of the membrane. In connection with the scapulo-humeral articulation, the remarkable vaulted arch placed above it remains to be described. This is constituted by the acromion and coracoid processes, and the intermediate ligament. It may be regarded as supplemental to the * Lancet, 1829-30, p. G72. 576 SHOULDER JOINT —(Normal Anatomy). shoulder joint, and as being intended to com- pensate i'or the incomplete reception of the head of" the humerus by the glenoid cavity. The centre of this arch is formed by the coraco- acromial or triangular ligament, of which the apex is situated at the acromion, and the base at the outer edge of the coracoid process. The ligament consists of two bundles, sepa- rated by a cellular interval, and placed more anteriorly the one than the other. The acro- mion and coracoid processes constitute re- spectively the extremities and the points of support to the arch, whilst its under surface is accurately adapted to the convexity of the head of the humerus, the tendon of the supra- spinatus muscle intervening. The existence of the large bursa (elsewhere noticed) between this tendon and the coraco-acromial ligament, abundantly proves that considerable motion takes place between them : the upper surface of the ligament is concealed by the deltoid muscle. In this arrangement may be recognised a provision for protecting the shoulder-joint against violence from above (Voute jjrotcc- tatince, Blaudin), and the humerus against displacement from below, either directly up- wards or with an inclination backwards or forwards. And for such a provision there is the greater necessity, as the upper extremity is constantly exposed to forces which act upon it from below. Mechanical functions. — In common with other enarthrodial articulations, the shoulder joint enjoys the following varieties of motion : 1. Flexion ; 2. extension ; 3. adduction; 4. ab- duction ; 5. circumduction ; and 6. rotation. 1. Of the opposed motions of flexion and extension, the former possesses the greater latitude. When carried to its utmost extent, the humerus appears to move through the arc of half a circle of which the centre is at the joint ; for the arm from being parallel to the trunk in the direction downwards, may by this motion be raised vertically upwards. 2. Extension, on the other hand, is much more limited, being restrained by the great strength of the anterior portion of the capsule, by the inter-articular ligaments, and by the contact of the head of the humerus with the coracoid process, which are all calculated to check the advance of the head of the humerus, the necessary result of extension. Flexion and extension, although apparently performed in the scapulo-humei al articulation solely, are really distributed over a much more extended sphere, being shared by the scapula, and by the articulations of the clavicle with the acromion and with the sternum. When extreme flexion or extension takes place, the scapula undergoes a motion of rotation upon its axis (an imaginary line i)ass- ing through the centre of the bone) ; and the result is, that when the humerus is flexed the superior angle of the scapula moves back- wards, and its inferior angle forwards , wht reas, in extension of the arm, a change of position the reverse of this is produced in the scapula. This rotation of 'the scapula is favoured by the looseness of the ligamentous connections of the acromio-clavicular articulation, whilst it is restrained within bounds by the coraco- clavicular ligaments (conoid and trapezoid). The trapezoid limits the advance of the upper angle of the scapula ; the conoid checks the rotation which would carry it in the opposite direction. The muscles which chiefly effect the rotation of the scapula are, the trapezius, latissimus dorsi, levator anguli scapulae, rhomboidei scapu- las, serratus magnus anticus, and the pectoralis minor. Of these the trapezius and serratus magnus rotate the scapula, so as to elevate its acromial end ; whilst the rhomboidei muscles and the pectorahs minor produce the contrary effect ; the latissimus dorsi can only act on the scapula when it takes an origin from its inferior angle. If it were possible for the levator anguli scapulae to act independently of the other scapular muscles, it would depress the acromion ; but as this rarely, if ever occurs, its ordinary action is to assist those muscles which elevate the entire scapula, and, conse- quently, the shoulder joint. 3. The motions of adduction and abduction are remarkably contrasted : the former can hardly, with strict propriety, be said to exist, being prevented by the immediate contact of the arm with the side ; adduction, however, in an oblique direction forwards and inwards, is permitted. This motion is limited by the projection of the thorax : when the arm is placed in this position the head of the humerus is strongly pressed against the posterior por- tion of the capsule, and if force -were to be applied to the distal extremity of the lever under these circumstances, dislocation back- wards might be produced. 4. The motion of abduction is the most extensive of those enjoyed by the shoulder- joint ; it permits the separation of the arm from the side, until it becomes parallel to the trunk in a direction upwards ; flexion has been stated to be capable of the same range, but the latter owes much of its freedom to the mobility of the scapula, whereas in abduc- tion the scapula moves but little, and nearly all the motion takes place in the scapulo- humeral articulation. Abduction is limited by the contact of the neck of the humerus with the acromion, and by the resistance of the capsular ligament. When fully performed, the head of the humerus revolves in the glenoid cavity, and in its de- scent presses strongly against the inferior portion of the capsule ; if force be now ap- plied to the upper extremity from above, the ligament may give wav and dislocation be effected. More frequently this accident oc- curs when the arm is moderately abducted, and the mechanism b} which, under such cir- cumstances, it is effected, may be briefly ex- plained. When a person falls on the inside of the elbow, while the arm is abducted, the upper extremity represents a lever of the third order, of which the fulcrum is at the point of contact of the elbow with the ground, and the power at the " folds of the axilla;" the at- ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 577 tachment of these muscles at right angles to the lever, and at a considerable distance from the fulcrum, enables them to act at a great mechanical advantage, and their sudden con- traction makes the upper end of the humerus to become the moveable extremity of the lever, and presses it against the capsule, which giving way between the triceps and the sub- scapuiaris muscles, allows the bone to escape into the subscapular fossa. The long diameter of the glenoid cavity being vertically placed is favourable to the motion of abduction, and in some degree lessens the liability to dislo- cation, to which the joint is so prone in tliis position, whilst on the other hand the com- parative fixity of the scapula when the arm is being abJucted, explains in some degree the frequency of dislocation of the humerus down- wards. 5. Circ2cmd action is compounded of the preceding motions, the flatness of the humeral tuberosities and the shallowness of the glenoid cavity rendering it very extensive in subser- vience to the variety of uses of the uj)per ex- tremity. Circumduction is much more limited in the hip-joint, as there, the anatomical conditions which favour this motion in the shoulder are wanting, freedom of motion being sacrificed to security. 6. Rotation is imperfectly developed in the fchoulder joint, but it exists in great perfection in the hip, as a necessary consequence of the great development of the neck of the femur. {Ben. Geo. M'Dowel.) SHOULDER JOINT, Abnormal Con- ditions OF. — The alterations from the normal condition of the shoulder joint, which we have observed, may be classed under the three fol- lowing heads : — First, those which are pro- duced by disease ; secondly, those causetl by accidental injury; and, thirdly, those which are the result of congenital malformation. Section I. — Uiscase^ — The abnormal appearances observed in the joints in gene- ral, and in that of the shoulder in particular, resulting from disease, owe their origin to some local injury done to the joint, or to some specific irritation, such as gout, rheu- matism, syphilis, struma, &c. Whether the disease first commences in the bone, the cartilage, or synovial membrane*, it soon in- volves all the structures of the articulation in the same morbid action, and with the local affection is usually associated some form of inflammation, either acute or chronic. Acute arthritis of the shoulder. — The symptoms of acute inflammation of the shoulder joint will be found to be similar to those we have elsewhere in this work described as being present, when some of the other large articulations have been affected by it.f The patient will feel considerable pain in the shoulder joint, to the front of which he will point as the seat of his most acute suffering. This pain is aggravated by the slightest touch, * Sec Hii' Joint, Vol. 11. p. 790. t See Vol. III. pp. 49—55 ; IIip Joint ; ;;lso Vol. II. pp. 788—792. VOL. IV. or when any movement is communicated to the joint. The patient himself carefully pre- serves his arm immovably in one posture as he lies in bed, with his elbow abducted from his side, and his hand supported in the state of supination. Effusion of altered synovia, or purulent matter, rapidly takes place into the synovial sac of the articulation. There is much heat of the surface and tension of the skin. The pain which, as already mentioned, is felt on the front of the shoulder joint, soon ex- tends down the arm to the inside of the elbow-joint, and the patient complains of spasmodic startings of the limb, and cedema of the whole extremity may supervene. The distention of the synovial sac of the articu- lation increases, and the surgeon can discover a fluctuation along the anterior or posterior border of the deltoid region, and he may find it expedient, with the view of relieving pain and tension, to make an incision into the joint, and thus give exit to a large quantity of purulent matter. Irritative, or it may be in some constitutions inflammatory, fever accom- panies these symptoms, and the patient may be carried oflf" even before the period when the purulent matter shall have made its way to the surface ; or the acute inflammation may subside into chronic arthritis, and articular caries of the shoulder joint be established, to run its subsequent course as a chronic disease. The acute form of the disease only differs from the chronic in the former being more intense in its attack, and in being accompanied with swelling of the joint — in being more rapid in its course, and more speedily pro- ducing complete disorganisation of the arti- cular textures. Anatomical characters of arthritis of the shoid- der. — Very few opportunities are offered to the anatomist of witnessing the appearances which the several tissues of the shoulder joint pre- sent when they have been the seat of acute inflammation ; we may, however, safely infer, that the articular structure of this joint will be altered in a similar manner in consequence of an attack of acute arthritis, as the corre- sponding tissues in other joints have been already described.* Chronic arthritis of the shoulder. — We meet, in practice, with two forms of chronic arthritis of the shoulder. The first of these oc- curs as an example of slow inflannnation passing into either articular caries or anchylosis of the joint, and is analogous to the well-known scrofulous disease of the hip. The second furnishes us with a specimen of a chronic disease, which the writer has elscichcre in this work denominated chronic rhcnmutic arthritis f ; a disease, the effects of which are to be traced in all the articulations, but its peculiarities are in no joint better exemplified than when the shoulder becomes the seat of it. We shall first treat of the abnornal ap- pearances produced by the disease we call * Vide Vol. in. p. 54. t See Hand ; Hip Joint ; Elbow, &c. &c. P P 578 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. simple chronic arthritis of the shoulder; se- condly, we shall describe those which belong to chronic rheumatic arthritis of the same arti- culation. While the two chronic diseases of the hip, namely, the scrofulous affection and the chronic rheumatic arthritis of this joint, have of late years attracted much attention from the profession, it appears to the writer of this article that the corresponding diseases of the shoulder joint have been much overlooked. He hopes, therefore, he shall be excused if he deems it necessary to enter into more than ordinary details relative to the two chronic affections of the shouKler joint, which he will now endeavour faithfully to dehneate. Simple chronic arthritis of the shoulder may be the result of a sprain or contusion : the synovial and fibro-synovial structures are in this case principally affected. If, however, the inflammatory action be not arrested, the bones, as well as their cartilaginous incrusta- tions, become ultimately engaged, and true articular caries is established. The disease sometimes begins in the shoulder joint, with- out the patient being able to assign any cause for it ; and in this case it may have a consti- tutional origin, and be the result of struma, or acute rheumatism, which last having sub- sided in the other joints, has concentrated itself on this one articulation, assuming the form of an articular caries. We have known it also appear in a young female during the convalescence from a long-continued gastric fever. Symptoms. — The first symptoms the patient suffers from, who is affected with simple chronic arthritis, or articular caries of the bones which enter into the formation of the shoulder joint, is a sensation of weight, weari- ness, and aching in the affected arm. These signs of the disease are at first not constantly present ; they appear and then disappear, to return again in some days. Some stiffness in moving the affected arm is next complained of, to which is soon added pain, which the patient says is deeply seated in the joint, and which is augmented by using the articulation, or when the articular surfaces are pressed against each other. These symptoms are seldom so severe as to prevent the patient from following his ordinary occupations. So far the disease may be said to be merely in its commencement ; but very soon we ob- serve it to pass into the second stage, when it may be discovered, on minute inquiry, that there is some sympathetic disturbance of the system — some heat of skin and slight acce- leration of the pulse. On exan)ining the affected joint, we observe that the patient habitually carries it higher than the opposite shoulder, and the clavicle at the affected side is observed to pass, as it were, obliquely upwards and outwards, the adipose and cellular tissue, as well as all the muscles around the shoulder joint waste. The deltoid muscle, in a state of atrophy, appears stretched longitudinally, and the affected shoulder to have lost much of its normal roundness. The acromion process j)rojects (see Jig. 427.), and the arm of the affected side appears, and is usually found, on comparative measurement, to be really lengthened ; the anterior fold of the axilla is deepened by the descent of the humerus from the glenoid cavity. The pain increases, and extends downwards from the shoulder to the inside of the elbow and wrist. In the third period the disease, the wasted condition of the muscles around the shoulder joint, as well as those of the whole upper extremity, becomes still more obvious, and now the arm, which was really longer than natural, becomes gradually shorter. It is quite possible that, after the limb has become shortened, any pain or uneasiness felt in the joint may subside, and a process of true anchylosis be established before suppuration takes place ; but it much more frequently occurs, that about the time of the shortening of the limb, or subsequently, a chronic symp- tomatic abscess will make its appearance, and perhaps open spontaneously, in the axilla, or on some point along the outline of the deltoid, or inferior margin of the pectoral muscle ; and then the disease may be said to be in the fourth stage. This very serious chronic disease of the shoulder may be sometimes arrested in its early stage, and the patient recover the use of the joint; but, on the other hand, the disease frequently ends unfavourably by hectic fever, with its fatal consequences supervening. The more usual course for the disease to run will be found in general to be, that suppuration will take place, abscess after abscess will form, their purulent contents escaping and con- tinuing to flow, greatly exhausting the strength and spirits of the patient ; but under the in- fluence of good air and judicious management, the discharge from the abscesses may cease, the constitution improve, and true bony an- chylosis of the shoulder joint be established. The history of the two following cases of simple chronic arthritis of the shoulder, at this moment (June, 1848) under treatment at the Richmond Hospital, will serve to illus- trate some of the preceding observations as to the symptoms which patients usually labour under when affected by this chronic disease. Case 1. Chronic arthritis of the right shoulder joint of four years^ duration. The disease in the second stage. — Margaret Moore, a^t, 27, servant, admitted March 8th, 1848, under the writer's care. She complained of stiff- ness and weakness of her right shoulder {Jig. 427,), and of pain, w^hich was much worse at night than during the day ; she had also a constant uneasiness at the inner side of the right elbow% and her nights were restless, her sleep interrupted by spas- modic starting of the whole limb, and pain extending down to the wrist and back of the hand ; she states that she has really more pain in the elbow and wrist than in her shoulder, and that these pains are increased when the arm is moved, or the articular sur- faces are pressed against each other. When- ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 579 ever she moves her arm in the gree the scapula follows the Fw. 427. slightest de- humerus, so Case of M. Moore : Articular caries of the shoulder joint ; second stage of the disease. fight that in the voluntary movements of the upper extremity really no motion takes place in the shoulder joint ; but if we grasp the scapula, and thus firmly fix it, and at the same time move the humerus, a distinct crepitus is oc- casionally elicited, of which the patient her- self also is conscious. When the arm is per- mitted for a moment to hang down by her side unsupported, she has great pain, and she feels the advantage of keeping it constantly in a sling, with her hand as high as her oppo- site collar bone. The muscles surrounding the right shoulder joint were observed to be in a wasted condition ; this shoulder seemed higher up than the other, and the clavicle of this side to have a corresponding obliquity. The history she gives of the origin and progress of this disease is, that she has had a certain degree of pain and uneasiness in the articulation for the last four years, but that it never swelled much nor became in- flametl, nor did it prevent her from follow- ing her occupation as housemaid, until three months ago, when she felt compelled to give up her situation. She referred the aggrava- tion of her distress latterly to an injury the joint received from a severe fall she got down an entire flight of stairs. The latter circumstance in the history of her case made us more particular in our inquiries as to whether any fracture or dislocation could have occurred at the moment of this accident, and have been left unreduced. We were readily satisfied that there had been no frac- ture, as the affected arm was longer than the other. The deltoid muscle was flattened and the acromion was seen presenting an angular projection as in an old luxation ; yet the head of the humerus could be felt below the acro- mion; the anterior fold of the axilla was deeper than natural, but the elbow in this woman was placed habitually close to her side, and the long axis of the humerus could be traced by the eye to run nearly perpendi- cularly upwards towards the site of the gle- noid cavity, and not more inwards towards the axilla, as in the case of luxation. The atrophy we observed to affect the muscles in the vicinity of the diseased shoul- der joint in this case, was not confined to the deltoid and capsular muscles ; but the great pectoral was so much wasted that tlie ribs and intercostal interstices were seen con- spicuously on the right side, while the cor- responding spaces on the left side of the front of the thorax were sufficiently covered by muscle, &c. The right arm and forearm were more wasted than the left or unaffected limb, while the former extremity, measured from the acromion to the outer condyle of the humerus, shows an addition of length, or rather a descent of the humerus from the glenoid cavity, for the space of one inch. This woman has been subjected to the ordinary treatment for such cases ; she feels the necessity of supporting her arm, and not allowing it out of the sling during the day, while she walks in the open, air. The foregoing case presents us, as we have said, with a good specimen of the simple chronic arthritis, or articular caries of the shoulder in the second stage of the disease. It is probable that a slow process of bony an- chylosis will be ultimately established ; and the woman after a time may lose all pain, regain her general health, and ultimately recover, but with the impediment which must ever attend an an- chylosed shoulder joint. The course of the disease is not always so fav,ourable ; on the contrary, when the disease has arrived, as in the case of Moore just related, at the second stage, the pain is in some instances increased, the head of the humerus becomes wasted by caries as well as the surface of the glenoid cavity, when it will be found that the affected extremity, which was really longer than the other, shall have become shorter. This shortening, which marks the third stage of the disease, is frequently thought to be the result of complete dislocation ; but this occur- rence, the possibihty of which we do not deny, we believe, however, to be exceedingly rare. The shortening may be the consequence of caries and absorption of the head of the humerus, as well as of the surface of the gle- noid cavity. Under such circumstances the head of the bone may lean towards the axilla and subscapular fossa, or backwards to- wards the dorsum of the scapula ; or it may be elevated, so as to reach the concavity of the coraco-acromial vault, and be maintained there by the tonic force of the elevator nuiscles ; but we have not found it com- pletely dislocated as a result of caries. Case 2. Articular caries at the shoulder joint in the fourth stage of the disease, — Mary Ann Malloy, iet. 21, servant, admitted into the Richmond Hospital 25th July, 1847, under the care of Dr. Hutton. She has been now (June, 1848) eleven months p p 2 680 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. in hospital, and her left shoulder joint has in this period {^one through ail the stages of chronic arthritis ; and a process of anch> losis, with shortening of the left upper extremity, appears to have been nearly completed. Her general health seems at this time but little affected : several depressions along the mar- gins of the deltoid muscle, anteriorly and pos- teriorly, mark the situation of the numerous openings, most of which are now closed, through which purulent matter had escaped from the joint. The history which we collected of her case was, that about two months pre- viously to her coming to the hospital she fell backwards on her left elbow, to which acci- dent she ascribes her disease ; that subse- c|uentiy to this fall she felt pain in her left shoulder, but she cannot recollect that the joint swelled or became hot ; on the contrarj^ the shoulder always seemed to her, from the first, to waste, and to be colder (as it is at this moment) than the other ; except when the period of the formation of the abscesses arrived. She states that the movements of the joint, during the [U'ogress of the disease, were most painful, and that she had a sensa- tion of something grating in the joint when- ever the surgeon, in examining it, moved the arm. The arm is half an inch shorter th^n the other, and is closely approximated to the side : whenever abduction, flexion, or exten- sion of it is attempted by the patient, the scapula invariably moves also. The patient has no power of rotation of the head of the humerus on the scapula, nor can any move- ment of the kind be communicated. The head of the humerus in this case has not been dislocated, but its tendency is certainly backwards towards the infraspinatus fossa, where some fulness is perceived. The par- tial absorption of the head of the humerus, as well as the removal of a portion of the sur- face of the glenoid cavity by caries, which we believe has occurred here, will sufficiently account for the shortened condition of the arm. The most favourable prognosis we can form as to this case is, that a bony anchylosis of the shoulder joint will be established. In the first of these cases (M. Moore) it was very manifest that the limb was elongated; and in this second case (Malloy), when the disease of the shoulder joint had arrived at a much more advanced stage, it was equally evident that the length of the affected ex- tremity v.as diminished. We have adduced these cases as examples of what may be frequently expected to be seen by those who watch the course of articular caries of the shoulder joint ; but we must be prepared to meet with examples in which it may be ob- served, that during the whole progress of the disease the length of the limb will be neither increased nor diminished. Varieties analogous to this we notice in the symptoms and [)ro- gress of articular caries when it affects other joints (see Hip Joint); and therefore we need not be surprised, when the shoulder joint is the seat of chronic arthritis, that sometimes the extremity of the affected side is shorter, sometimes longer, and that sometimes during the whole course of the disease but little al- teration as to increase or diminution of length is appreciable. Anatondcal characters of chronic arthritis of the shoulder. — The specimens we have an opportu- nity of examining anatomically, which show the ultimate effects of chronic arthritis on the se- veral structures composing the shoulder joint, cannot be considered very rare ; but it must be confessed that we seldom can ascertain the condition of the different structures of the shoulder joint which have been affected by chronic arthritis, excepting in cases in which the disease has arrived at its last stage, and has been the cause of the death of the patient. On making the post-mortem examination of the affected shoulder in cases where the dis- ease has arrived at its last stage, we usually notice that the skin has been perforated by numerous fistulous openings; these are some- times to be seen in the axilla, or ranged along the line of the margin of the deltoid muscle, perhaps at points more distant from the joint, as on the lower margin of the pectoral muscle near the mamma (case of Malloy). The subcu- taneous cellular structure we have not found infiltrated, as it is in cases of white swelling of the knee, or of the other joints, with a ge- latinous glairy matter; on the contrary, the cellular structure itself has always seemed to us to be in a wasted condition, containing no adeps ; the deltoid as well as the arti- cular muscles have been found in a state of atrophy. The bursa underneath the deltoid muscle has been observed to have been the seat of an effusion of fluid, quite distinct from that contained within the capsule of the joint; the internal surface of the bursa as well as the synovial lining of the fibrous capsule have been also found coated with lymph. Sometimes in advanced cases the fibrous capsule has been found much contracted as well as thickened, and having numerous per- forations in it, which had been the internal orifices of several fistulous canals, which having opened externally had acted as ex- cretory ducts, as it were conducting purulent matter from the different points of the carious surfaces of the bones of the joint, and even from the centre of the diseased head of the humerus. In all of the advanced cases that we have examined, the tendon of the biceps, so far as its intra-articular portion is concerned, has been removed. The articular surfaces have been always divested of their cartila- ginous incrustations, and the reticular struc- ture of the head of the humerus, and of the scapula where it forms the glenoid cavity, usually exposed and bare sometimes coated with a layer of puriform lymph. Part of the head of the humerus has been removed, and in what remains of it deep digital depressions have been observed, and foramina, which pene- trate even into the centre of the head of the bone. M. Bonnet, of Lyons, states, "that on making (he post-mortem examination of one ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 581 of his patients, who died of articular caries of the shoulder joint, he discovered, when a vertical section was made of the humerus, that in the centre of the head of this bone there was contained a cavity or cell, the size of a hazel nut, filled with tubercular matter, in the middle of which were found fragments of necrosed particles of bone. In this case also, he adds, tubercular matter was found in the axillary glands."* Bony nodules and stalactiform osseous productions are observed to be produced from different parts of the scapula and head of the humerus, in the vici- nity of the shoulder joint. The coracoid process and acromial end of the clavicle we have found in these cases carious ; the alter- ations of the osseous structure do not seem confined to the bones in the immediate vici- nity of the joint itself. The whole scapula and humerus seem specifically lighter than they should be normally. We have tried the experiment of placing the diseased bones in water, and have seen them float, while the normal bones of the same region sink. The ribs, too, have been found sometimes carious simultaneously with the bones which con- stitute the scapulo-humeral joint. These observations refer merely to the local condition of the articular structures them- selves. The state of the constitution of many of these cases affected with chronic arthritis of the shoulder deserves the attentive con- sideration of the physician and surgeon. The prognosis to be formed as to any ad- vanced case of articular caries of the shoulder joint should be a guarded one, as the follow- ing facts may convince us. In the first case which we shall now adduce, fatal disease of the lungs seemed coincident with the articu- lar caries of the shoulder ; and at last it was doubtful which of the two diseases was the im- mediate cause of the death of the patient. In the second case disease of the brain, with paralysis, came on, and was the immediate cause of the death of the individual, who had been previously much reduced by articular caries of the shoulder. Case 3. Chronic arthritis or articular caries of the shoulder joint, lasting thirteen months. — Matthew M'Cabe, a labourer, aet. 38, was admitted into the Richmond Hospital, Sept. 2. 1846, under Dr. Button's care.f He stated that about nine months previously he w^as seized with a pain in his left shoulder, which soon extended to his elbow; he was able to work for two months after the first attack of pain, but after this period the arm became stiff, and remained powerless by his side ;. the muscles around the shoulder and of the whole extremity were wasted ; fistulous open- ings existed beneath the coracoid process, and through the deltoid muscle ; the limb was of its normal length. When the joint was pressed the patient complained of pain ; the motion of the head of the humerus on the glenoid ca- vity of the scapula appeared much limited ; * Traite des Maladies des Articulations, t The writer is indebted to Dr. Hutton for the ftotes of this case. he had cough and hectic fever, of which the prominent symptoms, beside the cough, were a quick pulse and diarrhoea. He died Jan. 25. 1842. Post-mortem examination. — The body was emaciated. Before making the examination, a plaster of Paris cast was taken of the left shoulder joint, which is preserved in the hos- pital museum : this shows especially the wasted condition of all the muscles around the shoulder joint, and the consequent prominence of the spine and acromial process of the scapula, usual in cases of articular caries of the shoulder. For the space of two inches along the anterior wall of the axilla and line of the humerus an oblong depressed scrofulous ulcer existeil, in which were seen the orifices of three or four fistulous canals, which led fi'om the interior of the joint. The elbow was placed somewhat backward, and the long axis of the humerus was consequently directed, from below up- wards and forwards ; the convexity of the head of the humerus, without being dislocated, was placed somewhat more forwards and in- wards than natural. Upon removing the deltoid muscle, which was wasted and per- forated by fistulous openings, it was found that the capsular ligament was contracted and thickened, and had several openings in it, and that purulent matter was effused both into the joint and under the deltoid muscle, which thus formed the sac of an ab5:cess. The car- tilages had been entirely removed from tlie ar- ticular surfaces. The intra-capsular portion of the tendon of the biceps had disappeared ; the highest part of this tendon which remained was attached to the inside of the capsular ligament. The bones had been injected with size and vermilion, and presented in their interior as well as on their carious surfaces a reddish colour; but they did not appear softened; when after maceration they had been dried, they seemed to be preternaturally light. The superior hemispherical portion of the head of the humerus had been removed very nearly to the level of the anatomical neck, or situation for the attachment of the capsules ; and the surface was red, porous, and much rough- ened from caries. Towards the highest part of the humerus, just within the line which separates the great tuberosity from the head of the humerus, there existed two very deep digital or alveolar depressions, which pene- trated into the cellular structure of the head of the humerus : the anterior part of the upper extremity of this bone, where the bicipital groove exists, was rough and porous ; the groove was much deepened, particularly in the situation of the lesser tuberosity, which was elevated into a bony nodule, and enlarged about one inch below the lesser tuberosity. On the front of the surgical neck there existed another bony nodule, but smaller. The surface of the glenoid cavity seemed to have been somewhat worn away and rendered more than naturally concave ; the anterior or inner margin of it was rounded off by caries. The oval outline of the glenoid cavity was elon- gated from above downwards, and somewhat p p 3 582 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. narrowed transversely. The axillary margin of the scapula, where the long head of the triceps arises, was furnished with the friable stalactiform osseous productions, which we have already noticed to have existed around the articular surfaces of ail the other articu- lations, when they had been for a long time the seat of strumous arthritis, or scrofulous caries of the joint.* The rest of the scapula had a rough scabrous aspect ; the coracoid pro- cess presented the appearance also of having been in a commencing state of caries. The external lamina of the bone had been absorbed ; the exposed reticular structures of it were so friable, they would crumble under the slightest pressure.f The lungs presented the ordinary appear- ances of phthisis in its last stage ; there were tubercles and tubercular excavations in both iungs. In this case the disease of the shoulder joint seemed to have arrived at its last stage, and to have been in itself sufficient to have induced a fatal hectic fever. However, co- incident with the articular caries appeared the disease of the lung, which caused, or at all events hastened, the death of the patient. Case 4. Articular caries of the shoulder in the fourth stage.X — Edward Brady, set. 36, a baker, was admitted into the Richmond Hospital, 6th of May, 1S28, labouring under disease of the right shoulder joint. It appeared that he had had for some time previously a chronic inflammatory affection of this articulation, for the origin of which he knew no cause ; that an abscess had formed, and that matter had made its way through the skin just beneath the point of insertion of the pectoralis major into the humerus, where a fistulous aperture ex- isted, which daily gave exit to a considerable discharge of purulent matter. On admis- sion into the hospital, the right shoulder joint was swollen, the man was emaciated and in a state of debility, his pulse quick and weak ; he complained of pain when the slightest pressure was made on the joint, or motion communicated to it. From the short notes of the patient's symptoms during the two last months of his life when in hospital, we learn, that after five weeks' treatment, such as local bleeding and counter-irritations, as bhsters, &c., he was not really better. On the contrary, "the patient was much debili- tated, the hectic symptoms had increased, the shoulder v.as flattened, the motions of the joint were circumscribed within very narrow limits, the acromion was prominent as in axillar}' dislocation." In another month, viz. July 12, we find entered the following re- port:— " No improvement either locally or constitutionally ; the shoulder is more ema- ciated, and a crepitating, grating sound is el'- cited on rotating the humerus ; the hand is * Vide Hip .Joixt, Abxormal CoxDmox of, Tol. II. p. 704.^^^. 311. t Museum, Eichmond Hospital. j This case has been extracted from the case book of the late Dr. Macdowell, whose accuracy of obser- vation and fidelity were well knoT.Ti to the editor of this work as well as to the WTiter. slightly cedematous, yet the discharge is less profuse, and considered of a more healthy ap- pearance." Eight days subsequently to this report the patient became comatose, and died in the course of a few hours. Post-mo7'tem examination. — The subcuta- neous cellular structure which covered the deltoid muscle of the affected side was desti- tute of all adipose tissue; the deltoid was pale and thin ; the sub-deltoid bursa contained a sanious fluid, which being removed it was seen that the bursa had been lined with lymph ; the fibrous capsule, ulcerated at one point, was thickened, as was the synovial membrane, which was pulpy; the articular cartilage was entirely removed from the head of the hume- rus and surface of the glenoid cavity of the scapula. The superior extremity of the former was almost totally destroyed, the bone having been crumbled down into many small portions. The surfaces were covered with unhealthy looking pus and lymph. The long tendon of the biceps had disappeared ; the surface of the glenoid cavity was carious ; the small muscles about the joint resembled the deltoid as to the state of thinness and atrophy they had been reduced to. The sinus leading to the point in the axilla already mentioned was lined with lymph. The disease of the shoulder joint in this case, it appears, had, as in the preceding, ar- rived nearly at its last period, and we might have supposed that the morbid state here described of so important an articulation was of itself sufficient to cause a fatal result, when the affection of the brain suddenly supervened, and became the immediate cause of the death of the patient. It were very desirable that we could assign to the four periods of this disease of the shoulder joint, when affected by chronic ar- thritis, the anatomical characters which belong to each stage respectively ; but we repeat, we are as yet only trul}' acquainted with those appearances which the post-mortem exanii- nations exhibit of the ultimate result of the disease as it has afl^ected the articular tex- tures, when it has been the cause of the death of the patient. The pathological condition, therefore, of the different tissues which enter into the com- position of the shoulder joint, as they are af- fected in the early stages of this chronic dis- ease, is as yet, we believe, but little known. The most remarkable features of the second stage of chronic arthritis of the shoulder joint we notice, is the descent of the head of the humerus from the glenoid cavity, and conse- quent elongation of the upper extremity of the affected side. This, we conjecture, may be accounted for bv recollecting that the del- toid and articular muscles, which in their normal state maintain the head of the humerus close up against the glenoid cavity, are now in a state of atrophy. They have from want of use, and perhaps, also, from sympathy with the dis- eased state of the articular structures, lost all tonic force. Although these muscles are not really paralysed, still they seem not to have ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 583 power enough to resist the influence of the weight of the upper extremity ; and hence the head of the humerus, unrestrained by the naturally loose capsular ligament, descends to the extent of half an inch or an inch from the glenoid cavity. There can be but little doubt, also, that in the second period of the disease we are now considering, an effu- sion takes place into the interior of the syno- vial capsule of the joint : this may be altered synovial fluid or ljm[)h, or purulent mat- ter to a small amount ; but whatever the effusion be, it also will have the eflect of par- tially displacing, and causing an elongation of, the upper extremity. It may be asked how it happens that the head of the humerus, once partially displaced downwards, does not become subjected to a secondary displacement inwards, under the influence of the contractions of the pectoral and other muscles? The answer may perhaps be, that, in the second stage of this disease, the long tendon of the biceps retains its form, place, and functions ; so long as this tendon remains in its state of integrity, arching over the head of the bone, and then passing in a perpendicular line down along the humerus, the head of this bone cannot be partially ele- vated above its normal situation, nor even drawn inwards or backwards by either of the great muscles which form the anterior or pos- terior walls of the axilla; but when the long tendon of the biceps is destroyed, as it very generally is in the third stage of this disease, then the head of the humerus may be moved in whatever direction the inclination of the new plane formed by the altered surface of the glenoid cavity may give, or the muscles may draw it in. In the third stage of chronic arthritis of the shoulder, the bones which compose the joint are carious, and their surfaces are partially and unequally removed ; the length of the ex- tremity may be diminished. The long tendon of the biceps is removed, and hence no longer influences the position which the head of the humerus is ultimately to take, whether the bone in this third stage be partially displaced upwards, forwards, or backwards, i Some of the surrounding muscles are in this period of the disease in a state of atrophy, while others retain their form and functions. The proper articular muscles, whose normal function it is to keep the head of the humerus close to the glenoid cavity, are, in the third stage of disease, wasted ; and besides, as their capsular attachment is usually in this advanced stage of the disease destroyed, their influence becomes annihilated. The pectoralis major may draw the head of the bone towards the median line ante- riorly ; the latissimus dorsi and triceps pos- teriorly towards the dorsum of the scapula; and several muscles, such as the attenuated deltoid, the coraco-brachialis, &e., may ele- vate the head of the humerus, so as to bring its upper surface into contact with the acro- mion and coracoid process. We cannot prele7id to say what it is which determines the line of direction the head of the humerus in these partial displacements which occur from disease may take, or explain why the bone should in some cases take one direction, and why occasionally another ; no more than we can assign any cause for the various direc- tions the head of the femur takes in the third stage of scrofulous caries of the hip joint, a disease we consider analogous to this we are now considering. Anchi/losis of the shoulder joint. — Anchy- losis of the shoulder joint may be observed to be one of the terminations of an attack of acute or chronic arthritis of this joint. It may, we think, be remarked generally as the result of true bony anchylosis of any of the joints of an extremity, that shortening of the limb shall have taken place. This observation seems to be exemplified by what we commonly observe in studying the characters of true bony anchylosis of the shoulder joint. Most of the specimens preserved in our collection at the Richmond Hospital museum and else- where, present examples of solid union of the bones which compose the shoulder joint ; partial displacement upwards of the head of the humerus, and slight shortening of the ex- tremity having previously taken place. There is at present in the museum of the Richmond Hospital a specimen of complete bony anchy- losis of the shoulder joint, which was exhi- bited by Dr. R. Smith to the Pathological Society on the 13th March, 1841, along with some other examples of anchylosis of this joint. " The specimen," observes Dr. Smith, " was taken from the body of an individual aged 90, who had been confined to bed for many years^before his death. The external appear- ance of the shoulder joint resembled some- what those of luxation of the head of the hu- merus into the axilla, so far as the acromion process having been prominent, and the joint in the region of the deltoid completely flat- tened; the arm was rotated inwards; the glenoid cavity and head of the humerus formed one continuous bone ; the greater tubercle was anchylosed by bone to the acro- mion process, while the coracoid process was similarly joined to the lesser tubercle." Consequently the humerus must have been partially displaced upwards, and the arm shortened. The supra-spinatus and infra-spi- natiis muscles, as well as the subscapularis, had undergone fatty degeneration from want of use ; a change very commonly observed in cases of true anchylosis of long standing, no matter which of the joints has been the seat of this termination of arthritis. In the ex- ample just adduced the humerus was observed to have ascended, and the greater and lesser tuberosities had formed a solid union with the coracoid and acromion process ; but in some examples the anchylosis has been found to have taken place directly between the sur- face of the glenoid cavity and the head of the humerus ; and a vertical section of the bony structures running through the consolidated joint exhibited the cells of the original head of the humerus and the diplos of the scapula 584 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. freely communicating with each other, just as we have ah*eady noticed as exemphfied in complete bony anchylosis of the hip joint (see Vol. 11. of this work, p. 796.). It may not be uninteresting to transfer our attention from the appearances disclosed by the post- mortem examination of an anchylosis of the shoulder joint to the signs by which we re- cognise this state of the articulation in the living. A labourer, Thomas Rooney, aet. 24, ap- peared among the extern patients at the Richmond Hospital on Thursday, 8th June, 184-8, seeking relief for some internal ailment; we noticed the wasted condition of the right shoulder joint. We learned that about three years previously he had fallen on the right shoulder and injured it ; he applied for relief to an ignorant person called a bone setter, in whose hands he suffered severely, having been subjected to violent dragging, with the view, as he was told, of reducing a sup- posed dislocation of his shoulder ; violent in- flammation of the joint succeeded, for the treat- ment of which he was admitted into Steeven's Hospital. While in the house suppuration of the joint occurred, and purulent matter made an exit beneath the anterior fold of the axilla, where the tendon of the pectoralis major is inserted into the humerus. The pain and swelling then became less, and he returned to the country, the abcess and sinus leading from it closed up, and his general health became gradually as good as it liad been before he met with the accident, and remained so until he became affected with the trivial ailment he now sought advice for as an extern patient at the Richmond Hospital. The shoulder joint, on a superficial ex- amination, might be said to resemble some- what the appearance presented in a case of an old unreduced axillary dislocation, but the resemblance was but slight. It is true that the acromion process stood out laterally, that the deltoid was flattened, that the anterior fold of the axilla was deeper than natural, and that the angular appearance the right shoulder presented was strongly contrasted with the natural rounded contour of the left shoulder joint ; but the head of the humerus could be felt underneath the acromion process ; the elbow, instead of being separated from the side as in disolcation, seemed habitually ap- proximated to it. The biceps muscle, in consequence of the atrophied condition of the elevators of the extremities, had double duty to perform, and hence had been greatly hypertrophied at its lower part. The man can hold the plough, and can perform all the under movements of the arm very well, but cannot elevate it, nor place his forearm be- hind his loins. In this case the arm is habitually approxi- mated to the side, directed somewhat for- wards, and strongly rotated inwards. The most striking features in the case are the wasted condition of the shoulder joint from the atrophy of the deltoid and articular .muscles, and the extraordinary development of the lower part of the belly of the biceps the cause of which hypertrophy is easily un- derstood. We have seen cases in the living subject of perfect anchylosis of the shoulder joint, in which it seemed doubtful whether any short- ening of the extremity existed. In these cases we must suppose that the head of the hu- merus became directly consolidated with the surface of the glenoid cavity, and without the more usual union having been established between the upper extremity of the bone and the superincumbent processes. One of the most important points which engages the attention of the practical surgeon, in the treatment of cases of diseased joints at the period when it is expected that a process of anchylosis is going on, is to preserve the affected limb in that position which will be found most convenient to the patient, when true bony anchylosis of the joint shall have been established ; for example, under such circumstances we take care to preserve the knee and hip joints extended, the ankle and elbow joint bent to a right angle ; but the shoulder joint, when anchylosis is taking place, may be left to nature, so far as the position of the limb is concerned, because the humerus in these cases habitually remains nearly parallel to the long axis of the body, somewhat rotated inwards ; and, in a word, in a position which will be found most favour- able to the performance of those functions it shall called upon to execute when the scapulo-humeral joint is in an anchylosed state. Chronic rheumatic arthritis of the SHOULDER JOINT. — The shoulder joint is some- times the seat of this peculiar disease, though by no means so frequently as many of the other articulations. The origin of it we have known to be attributed to accident, such as a fall on the shoulder, or to a sprain of the joint. On some occasions the sudden exposure of the persoa, when overheated, to currents of cold air, has been referred to as its cause ; and in others the chronic disease of the shoulder joint has been supposed to have originated in the lingering reniains of a rheu- matic fever. These are, indeed, the ordinary exciting causes of this disease in general, no matter in what particular joint it may show itself. Sywptoms. — The patient complains of feeling pains in the shoulder joint, which, like those of rheumatism, are variable, and seem to be under the influence of changes in the atmosphere. He states that he feels a stiffness in the joint, and is conscious of a "crackling" sensation in it, particularly when he first moves it in the morning. The muscles around the articulation fall into a state of atrophy, while the bony prominences tiround the joint ge- nerally become conspicuous from their en- largement. If only one shoulder joint be affected with the ordinary form of the disease, and we com- pare it with that of the opposite side, the head of the humerus of the affected side will ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 585 be observed to be somewhat elevated, ad- vanced, and very generally approximated towards the middle line. When we view the articulation in profile (as it were), the amount of the advancement of the head of the hume- rus is more readily appreciated. And when we look at the shoulder joint from behind, a very remarkable abnormal depression mny be seen, which corresponds to the space or interval which exists between the posterior part of the glenoid cavity and the head of the hume- rus. After a time, the voluntary motions of the joint become restricted within very nar- row limits. The patient cannot well abduct the elbow from his side, nor elevate it nearly to an horizontal level. The motions he is himself capable of communicating to his arm are chiefly confined to under movements, yet the head of the humerus is in some of these cases susceptible of an abnormal degree of mobility. Although in the ordinary form of this disease the head of the humerus will be found to be placed above its normal level, and is observed to be several lines higher than the coracoid process, still if the arm be grasped by the surgeon it can be drawn down, and the head of the bone will place itself beneath the coracoid process ; the joint will then as- sume all the appearances usually assigned as the marks of the case styled by Sir A. Cooper " Partial luxation of the head of the humerus forwards and inwards." In cases of long standing, the capsular ligament becomes wider than natural, and the articular surfaces are so altered that partial dislocation of the head of the humerus occurs in other directions besides those above alluded to ; but any observations we have to offer upon this part of our subject it will be more convenient to defer until we come to speak of the anatomical characters of this disease. Although the patient may complain of pain in the middle of the arm, and of spasms of the muscles, of the whole extremity of the affected side, even to the fingers, yet if the surgeon elevate the arm at the elbow, and press the humerus even rudely against the glenoid cavity of the affected articulation, the patient experiences no tmeasiness. It is very remarkable that this peculiar affection of the shoulder joint has never, as far as we have known, terminated in anchy- losis, nor proceeded to suppuration ; nor has its presence excited any sympathetic disturb- ance in the constitution of the patient ; yet from year to year the disease slowly but gra- dually increases, until the patient is carried off by some other complaint, or dies from the mere effect of age alone. Diag?2osis. — This peculiar affection of the shoulder joint, particularly when the history of the case is known, cannot well be con- founded w^ith any other disease of the articu- lation with which we are acquainted. Scro- fulous -caries of the bones of the shoulder joint may have some symptoms in common with the chronic disease we are describing, but there is more pain and more wasting of the inuscles of the arm and fore-arm, and more sympathetic disturbance of the constitu- tion in the case of articular caries of the shoulder than in that of chronic rheumatic arthritis of this articulation ; and while the former case usually proceeds to suppuration, or to anchylosis of the joint, these processes never take place in the latter. In the chronic rheumatic disease, the op- posite shoulder joint will, in general, be found symmetrically affected ; a circumstance we have never yet known to have been the case in a chronic arthritis, or articular caries, of the shoulder. The history of the case of chronic rheuma- tic arthritis usually betrays its nature by the general rheumatic pains the patient reports himself to have suffered from ; by the disease not being confined to the one articulation ; by the enlargement of the bony prominences about the joint, although the muscles are wasted. In both cases there may be crepi- tus felt on moving the joint and on making pressure ; but the efforts to elicit crepitus, and the pressing together of the articular sur- faces cause, in the case of chronic arthritis, or articular caries, so much pain, that the patient shrinks back from our attem[)ts at making these trials ; while in the ordinary case of chronic rheumatic arthritis of the shoulder, when even it appears as a local disease confined to one or two articulations, we find we can even rudely press the heat! of the humerus against the surface of the glenoid cavity without causing the patient pain, just as we can, in the case of the same disease when it affects the hip joint, press the head of the femur against the acetabulum without causing the least uneasiness to the patient (see Vol. II. p. 799.). No doubt some few cases of chronic rheu- matic arthritis of the shoulder joint in the living and in the dead have been mistaken for partial dislocation of the head of the humerus, the rcsidt of accident ; but we are of opinion that, as the chronic rheumatic affection is daily becoming better known to the profes- sion than formerlv, such errors will no longer be committed, particularly w^hen the anato- mical characters of this disease have been more fully studied by the profession. Anatomical characters. — When we ana- tomically examine the shoulder joint of a patient who has long laboured under this chronic disease in the articulation, we notice on removing the integuments that the deltoid muscle is unusually pale, and that the inter- stices between its fibres are occupied by an unhealthy-looking fat. This and the sub- jacent capsidar muscles are in a state of atrophy. The capsular ligament is generally altered in form and structure, and it will be sometimes found to have abnormal attach- ments above to the acromion or coracoid process ; and, below, its attachment to the anatomical r^eck of the humerus is some- times partially interrupted, allowing of an interval which in some forms of the disease permits the head of the humerus to pass through it. 586 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. The capsular ligament is occasionally in- creased in thickness, and its fibres are hyper- trophied ; and it is generally more capacious than natural, showing that effusion of synovia to a considerable amount had existed, although the external signs of this phenomenon are not usually evident. When the interior of the synovial sac is examined, it will be found to present evidences of having been the seat of chronic inflammation. Bunches of long or- ganised fringes hang into the interior of the synovial sac ; and many of these vascular fimbriae, which in the recent state are of an extremely red colour, surround the corona of the head of the humerus. We also notice rounded cartilaginous productions, appended by means of membranous threads attached to the interior of the various structures which compose the joint. Some of these foreign bodies are small, others large. Some are round ; but their shapes are various. Besides these rounded cartilaginous bodies, we occa- sionally find osseous proiluctions of a mul- tangular form added to the edges of the gle- noid cavity, deepening it, and increasing the articular surface for the reception of the head of the humerus, which usually is in such cases much enlarged. The intra-articular part of the long tendon of the biceps is very seldom to be seen in the interior of the joint ; but immediately out- side of the capsular ligament the latter tendon will generally be found to have contracted a firm adhesion to the superior extremity of the bicipital groove {fig. 428. a.). Bones. — The head of the humerus assumes a very characteristic appearance as a con- sequence of this peculiar disease, and acquires a lorm which cannot be easily mistaken for the effects of any other disease or accident. The usual angle at which the head and neck of the humerus join the shaft of the bone is often altogether effaced ; so that instead of the axis of the head and neck of the humerus being directed, as it normally is, upwards, inwards, and backwards, it seems to run ver- tically, or, as it were, in a continuous line with that of the shaft of the bone. The articular surface is usually much enlarged, and in the ordinary form of this disease occu- l)ies the whole summit of the humerus, ex- tending itself even over the greater and lesser tuberosities and the highest part of the bi- cipital groove ; effacing in this direction part of the circular line which marks the anato- mical neck of the humerus and insertion of the capsular ligaments. Some of the articular cartilage is removed from the head of the bone, which, in some places, presents a porous appearance {fig. 428.). In other parts, in place of the cartilage, there is a polished ivory-like surface. The portion of the bone which thus presents this polished surface is the very summit of the humerus ; and this is the part of the bone which will be found evidently to have been for years in habitual contact with the under surface of the acromion and coracoid pro- cess, where these bones assist in forming por- tions of the new and abnormal cavity for the reception of the head of the humerus. The Fig. 428. a Chronic rheumatic arihntis : a, tendon of the biceps basis of the head, in the line where it joins the shaft of the humerus, is studded round by granular osseous productions, which give to it a characteristic a})pearance {fig. 428.). By these vegetations of bone, we are remintled of the analogous appearance which the corona of the head of the femur presents when affectetl by the same species of morbid action *; but of course much variety may be expected to be found in the form the head of the humerus will assume under the influence of this disease : we have found the articular surface in some cases formed completely on the summit of the hu- merus, sometimes on the side of the head. Very generally the head of this bone is much enlarged, but exceptions to this rule occur. One of the most remarkable alterations of form we have noticed as the result (as we imagine) of this disease we found in the anatomical museum at Leyden. In the spe- cimen to which we allude, the head of the humerus appears bifurcated at its upper part, or divided longitudinally into two surfaces for articulation with the scapula.-|- Lastly, we have to advert to the anatomi- cal characters of the new and abnormal socket formed for the reception of the altered head of the humerus. This new cavity is com- posed of two portions, which however will be found to have become almost continuous with each other. The original glenoid cavity (ge- nerally much enlarged) forms one of these portions ; the coraco-acromial vault the other. * Vol. U.fig. 317. page 802. t Saiulifort in liis fourth volume lias given a delineation of tlie liead of the humerus in this case as well as of the scapula tlie glenoid cavitj^ of which was enlarged xexy niucli in the direction downwards, and was sui rounded with a margin of osseous granules. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 587 By the coraco-acromial vault we mean a concave surface, looking downwards, formed internally by the coracoid process, and ex- ternally by the acromion ; the intervening space being filled up in front by the proper triangular ligament of the scapula, and com- pleted behind by a portion of the under-sur- face of the acromial end of the clavicle This coraco-acromial arch in the normal state overhangs much the head of the humerus, and its inferior surface is not articular, but, on the contrary, is separated from the head of the humerus, which is beneath it, by an in- terval of about three or four lines, measured in vertical height. This interval is normally occupied by the long tendon of the biceps and the capsular ligament, as they pass from the upper margin of the glenoid cavity to the hu- merus — the capsular ligament having above it the tendon of the supra-spinatus, a special bursa mucosa, much cellular tissue, and the fibrous bands, which pass from the humerus to the coracoid and acromial processes. Under the influence of the most usual form of this disease, all these parts intervening between the head of the humerus and the coraco-acromial arch or vault are absorbed ; and the superior extremity of the head of the humerus at length comes into immediate con- tact with the concavity of the arch. The first effect of this morbid process in bringing about the remarkable changes which we have been describing, may be to cause the absorp- tion of those tendons, viz. the supra-spinatus and the long tendon of the biceps, which pass over the head of the humerus, and which, by virtue of their muscular attachments, restrain within proper limits the degree of elevation * which the head of the humerus is normally susceptible of. When, however, these tendons are absorbed, and consequently the muscles to which they belong have lost all power of re- pressing the humerus, the latter is then drag- ged upwards, and its head being constantly pressed against the under-surface or concavity of the coraco-acromial arch, not only do the processes of the scapula which form this arch at length show manifestly the effects of fric- tion, but the outer portion of the acromial end of the clavicle does so equally. All these portions of bone are rendered con- cave, and are usually covered by a porcelain- like deposit, corresponding to an analogous polished surface which covers the convexity of the summit of the humerus. In many cases in v/hich the shoulder joint has long been the seat of this chronic disease, the acromion jjrocess has been found traversed in the line of junction of its epiphysis, by a complete interruption of its continuity, as if fractured : we say as if fractured, for we are convinced that this solution of continuity of the acro- mion process is not really a fracture produced by violence, but a lesion, which so frequently exists in combination with chronic rheumatic * If the long tendon of the biceps be dislocated find thrown inwards over the head of the hun:ierus, the same effects will be produced as if it -were ab- sorbed. arthritis of the shoulder, that we are com- pelled to look upon it, in these cases, as a peculiar organic change, the result of chronic rheumatic disease. We do not pretend to account for the separation of the acromion process into two portions ; nor can we say why it is that the division usually occurs in the original line of the epiphysis, particularly at the late period of life at which we generally witness this phenomenon. In some of these cases we have found the acromion in a state of hypertrophy ; in others in a state of atro- phy ; but in no case did there seem to be any attempt at ossific deposition on the contigu- ous surface of the separated portions of the acromion, a circumstance which might be ex- pected if a fracture hud occurred. The glenoid cavity of the scapula, under the influence of this disease, is generally much en- larged ; and by becoming wider above, it loses much of its ordinary ovoidal figure, approach- ing in its outline more to a circular form. The surface of the cavity appears preternatu- rally excavated, its brim being elevated into a sharp margin. The cartilage of incrustation, as well as the glenoid ligament, are generally removed altogether, some parts of the surface are porous, and some covered with porcelain- like enamel. Near the margins of the glenoid cavity, where the capsular ligament arises, we may often find osseous productions attached to the capsular ligament, adding depth to the receptacle for the enlarged head of the humerus. The glenoid cavity will of course be found to present nuich variety of form. Sometimes the head of the humerus occupies its upper portion, and habitually remains in contact with the under surface of the acro- mion and coracoid process, thus leaving the lower part of the glenoid cavity unoccupied. Sometimes part of the head of the hume- rus remains within the glenoid cavity, while the remaining portion of it occupies the neigh- bouring part of the subscapular fossa. Occa- sionally the head of the humerus will be found to have descended on the axillary mar- gin of the scapula * ; while in other cases equally rare, which we shall hereafter have occasion to refer to, the head of this bone may, under the influence of this disease, pass backwards on the dorsum of the scapula: under all these circumstances, the glenoid cavity must undergo special changes of form adapted to each variety. Those who carefully study the anatomical characters of chronic rheumatic arthritis of the shoulder, cannot fail in the course of their investigation to observe many deviations from the normal state of the joint, the result of this disease, which are well calculated to mislead those who are unacquainted with it ; to which we may here advantageously advert. It has been re[)eatedly remarked, that one of the most constant anatomical observations we had to make in post-mortem examinations of the shoulder joints of those w ho had been * Catalogue of the Museum of the College of Sur- geons, Dublin, vol. i. p. 399. Prepar. E. b. 905. 588 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. afFecteJ with chronic rheumatic arthritis was, that the long intra-articular portion of the tendon of the biceps was absent from the joint, although adherent outside to the highest point of the bicipital groove (^/?^. 428.). Thisremoval of a large portion of the tendon of the biceps strikes the observer who is unacquainted with this disease as a direct proof that the tendon had been ruptured by accidental violence, and that a partial luxation of the head of the hu- merus has been the consequence. Another character of this disease is, that the humerus has a very general tendency to pass upwards towards the coraco-acromial vault; and besides the removal of the tendon of the biceps, the superior part of the capsular ligament is observed to be deficient. Those who do not know that this perforation is a consequence of slow disease, immediately take it for granted that the same accident which ruptured the tendon of the biceps had also caused the head of the humerus to be partially dislocated upwards, perforating as it passed the superior part of the capsular ligament. If, in addition to these abnormal appear- ances, small portions of bone, as if fragments broken otf from the margins of the glenoid cavity, are found to be present, as they fre- quently are, this also is an appearance cal- culated to confirm an erroneous impression, that some external violence has been the source of it ; and if in addition the acromion process be found divided into two portions, as we have frequently noticed it, the preju- dice in the observer's mind may at first be strongly in favour of the idea, that accidental violence has been the source of these many and combined phenomena. But notwithstanding all these lesions, namely, the total disappearance of the articular part of the tendon of the biceps ; the perfora- tion of the superior part of the capsular liga- ment by the head of the humerus, and the separation into two portions of the acromion process, we feel convinced that all these phe- nomena combined should by no means be considered as proof of any accident having occurred to produce them ; but, on the con- trary, should be looked upon as the usual result of chronic rheumatic arthritis of the shoulder. The tendon of the biceps in all those cases of presumed accidents is said to be ruptured ; yet the chronic disease of the shoulder joint is frequently found to affect both shoulder joints in the same individual, and the long tendon of the biceps, in these cases, to be removed on both sides. It is easy to conceive that this double lesion may be the effect of disease, but difficult to imagine how any accidents could occur to "rupture" the tendons of the biceps in both shoulder joints. Nor is it easy to ad- mit that the long tendon of the biceps can be readily ruptured in partial dislocations of the humerus from accident, when we know that this tendon is rarely if ever ruptured, even in complete luxation of this bone. The statement made in the report of various cases in surgical works, and in the catalogues of Hjuseums, in which we find it briefly noted, " that the tendon of the biceps was found ruptured," has been made by the writers con- fessedly without any knowledge of the pre- vious history of the case, the anatomical cha- racters of which they are describing. On this account we feel t*ie less delicacy, after long and patient consideration of the subject, in expressing our conviction that the tendon of the biceps, in the numerous cases published, was not (as supposed to be) ruptured bv acci- dent, but absorbed as the result of disease. AVe have stated that the bones entering into the formation of the shoulder joints are very generally enlarged as a consequence of this chronic disease having for a considerable time existed in the articulation. It is right, however, here to observe, that very exten- sive inquiry into the pathological anatomy of this peculiar affection as it presents itself in the shoulder joint, will prove that some few exceptions to this rule may be occasionally met with ; and that, instead of the bones enter- ing into the formation of the shoulder joint being found hypertrophied, they may be dis- covered, on the contrary, to be in a state of atrophy ; or portions of these bones may be removed altogether, as the apparent result of this chronic rheumatic (hsease. That the writer may not appear to have been singular in having observed the changes which the acromion process and neighbour- ing bones have undergone as the result of this chronic rheumatic disease, he mav refer to the dissection of a case mentioned by Cruveilhier, in which the affection we have called chronic rheumatic arthritis was so ge- neral that there was scarcely any articulation in the body exempted from its effects. When adverting to the anatomical changes observ- able in the region of the shoulder in this ex- ample, he sa\s, the external extremity of the clavicle and the neighbouring part of the acromion were in a great part destroyed, dec* In the museum of the College of Surgeons in Dublin will be found a preparation of a shoulder joint, which is styled by the late Dr. Houston in his catalogue, a specimen of chronic rheumatic arthritis of tJie shoulder ; ancl that it was justly so styled may also be inferred from the " bunches of synovial fim- briae," which hung into the synovial cavity of the joint ; the existence of hydrops ar- ticuli, or over-distension of the synovial sac by an albuminous fluid ; and from the de- ficiency of the intra-articular portion of the tendon of the biceps, mentioned in the ac- count given of this case : — all these show the disease to have been correctly designated. The writer finds upon examining this prepa- ration with the intelligent curator, Mr. Carte, that the acromial end of the clavicle is ui> supported, and that the acromion process has been removed for the amount of an inch in extent ; that which remains for this process * Cruveilhier, livraison ix. p. 12. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 589 is thinner than natin-al, and in a state of atrophy.* The coracoid process is not usually found so much altered by the existence of this peculiar disease in the shoulder joint as the acromion; but we have found its under concave surface in some cases to have entered into the forma- tion of the shoulder joint, and to have pre- sented a broad glenoid-shaped surface, which had been smoothed off from frequent contact with the head of the humerus, while the breadth of the process had been at the same time much increased. We have thought it necessary to enter into this subject thus minutely, because we are convinced that, up to the present hour, these remarkable appearances, when met with, have been misunderstood even by some of the most intelligent anatomists and physicians. This circumstance may appear perhaps ca- pable of explanation, by recollecting that the disease generally runs a long course, is not in itself fatal ; and hence, although the practical medical man may have had numerous oppor- tunities of witnessing the symptoms of this disease in the living, he may never have had any opportunity in any case of informing himself of the true relation subsisting between the symptoms of this disease of the shoulder joint as observed in the living patient, and the 'phenomena which the post-mortem examina- tion of the same shoulder joint might have presented. On the other hand, when anato- mists have heretofore discovered in dissection appearances which are stated to be truly those of chronic rheumatic arthritis of the shoidder, they have not at that time been able to learn the previous history of the case. The following case may contribute some- what to supply this deficiency : — Case. Chronic rheumatic arthritis of the shoulder. — J. Byrne, a servant, aet. 55, was admitted into the Whitworth Hospital House of Industry in 1834. Dr. Mayne, at that time resident clinical clerk in the hospital, informed the writer that, besides the disease of the lungs, for v^hich the man was admitted, he also had an affection of the right shoulder joint, which presented all the characters at- tributed to the case of partial luxation of the humerus, and was kind enough to invite the writer to examine him. The man complained of an inability to use his right arm well, in consequence of his having for some years an affection of his right shoulder joint, in which he felt almost con- tinually a dull boring pain. He could how- ever perform, without much inconvenience, all those motions of the arm which did not require it to be raised near to the horizontal line. The joint felt to his own sensation somewhat stiff; and he was conscious, under certain movements of the arm, of a sense of something crepitating or crackling in the joint. Upon viewing the shoulder in front, it had a * See a preparation in the Museum of the College of Surgeons, Dublin, Catalogue, vol. ii. p. 397. E. 6. 901. wasted aj)pearance ; the acromion process was more prominent, rendering the bony eminences around very conspicuous ; the head of the humerus seemed to be a little higher than usual, and to have advanced somewhat forwards. The amount of advance was best seen by viewing the joint in profile or laterally. In this aspect a slight elevation and the increase of the antero-posterior measure- ment of the joint became very obvious. When the arm was pressed by the surgeon, and very slight force used, the humerus could be easily made to descend somewhat, and at the same time to pass a little beneath the outer margin of the coracoid process ; and the finger could be readily pressed into the outer half of the glenoid cavity, into the space which the head of the humerus was found to have aban- doned. When again the shaft of the humerus was elevated vertically, its superior extremity could be felt to strike against the under sur- face of the acromion. In a word, the symp- toms strongly resembled those usually as- signed to the partial luxation forwards and inwards. This patient remained in the Whitworth Hospital until the pulmonary affection proved fatal. Dr. Mayne and the writer carefully examined the joint, which is still preserved in the museum of the Richmond School (/g.429.). We found the deltoid and other muscles around the joint in a wasted condition, and much paler than those of the opposite shoul- der. When the capsular ligament was ex- posed, it was found to have superiorly a much wider and more extensive adhesion than natural. Instead of this fibro-synovial sac having its ordinary attachment all round to the limited circumference of the glenoid cavity of the scapula, its adhesion to the upper margin of this cavity did not exist, but the superior and outer portions of the capsu- lar ligaments seemed to have acquired new attachments, and to be connected superiorly and externally with the anterior margin of the coraco-acromial arch ; and thus the space in which the head of the humerus had been permitted to move, had been rendered much more extensive than natural. The capsular ligament was much thick- ened, and when opened more synovia than usual flowed out. This membrane was lined with cellular flocculi, and several small carti- laginous bodies, rounded, and of the size of ordinary peas, were seen to float in the inte- rior of the synovial sac, appended by means of fine membranous threads. All those parts which, in the normal condition, intervene be- tween the superior part of the head of the humerus and under surface of the coraco- acromial arch, were completely removed. No remnant or trace of the supra-spinatus tendon, nor any portion of the capsular liga- ment to which this tendon is attached, was to be found. The entire of the articular portion of the tendon of the biceps was absent, and the highest point of the remaining portion of the tendon was attached to the summit of the 590 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. bicipital groove. It was remarkable that the acromion process and other portions of bone, Fig. 429. Case of J. Byrne. — Clironic rheumatic arthritis. a, line of complete division of the acromion into two portions ; h, coracoid ]n'ocess ; c, acromial end of the clavicle, worn by the attrition of the head of the humerus ; d, tendon of the biceps adherent to the bone ; e, glenoid cavity ; /, capsule ■^^^den- ed ; foreign bodies attached to it. viz. the outer extremity of the clavicle and coracoid process, had acquired size and density., although their under surfaces were much worn and excavated where they formed an arch which overhung the hamerus. These appear- ances showed the great degree of friction and pressure from below upwards which these bones had been subjected to, from the head of the humerus being constantly drawn up- wards by muscular action. We also noticed that the acromion j)rocess luas traversed from within outwards by a perfect solution of con- tinuity, completely dividing it into two nearly equal portions. This might be supposed by some to have been a fracture which never had been united by bone — an opinion which, however, we did not entertain ; the two pieces of the acromion were on a perfect and uniform level, and the edges of the separated j)ortions of bone exhibited no evidence of any ossific de- posit, nor any such appearances as would lead us to infer that a fracture had existed. The glenoid cavity of the scapula was larger and deeper, and more of a cup-like form than usual. The cartilage of encrustation and glenoid ligament were removed, the sur- face of the cavity presented a porous appear- ance. Along its inner margin were arranged several round and firm cartilaginous granules. The head of the humerus was somewhat enlarged. The articular surface had become extended over the superior margin of the greater and lesser tuberosity. Much of the cartilaginous mvestment of the head of the bone had been removed, and its place supplied by means of a porcelain-like deposit. The line which marks the junction of the head of the bone to the shaft, was studded all round with granular elevations of bone (fg. 429.). Our knowledge of the anatomical cha- racters of this disease has now arrived at a degree of precision quite sufficient, we might suppose, to save us henceforth from falling into the error of confounding the morbid re- sults of chronic rheumatic arthritis of the shoulder with the consequences of chronic or acute osteitis, or with the ultimate ef- fects of accidents sustained during the pa- tient's lifetime. Nevertheless we feel called upon now to allude to some cases of partial luxation of the shoulder joint which have been published as the result of accident, but which we consider to be specimens of the chronic rheumatic disease of the shoulder joint which we are endeavouring to describe. Among these authors we find Sir A. Cooper, who, in his description of the acci- dent called by him "partial luxation of the shoulder joint, forwards and inwards, to the coracoid process," gives a case which he sup- posed to be one of this accident, and relates the symptoms to teach us how it may be re- cognised ; but for its anatomical characters he refers to an example found in the dissecting roon), the history of which was unknown. He says, '* The only dissection of this accident which I have had an opportunity of seeing was the following, for which I am indebted to Mr. Patey, surgeon in Dorset Street, ivho had the subject brought to him for dissection at the anatomical room, St.Thomas's Hospital. The following is Mr. Patey's account : — " ' Partial dislocation of the head of the os humerus. — The head of the os humeri on the left side was placed more forward than is na- tural, and the arm could be drawn no farther from the side than the half way to an hori- zontal position. *' ' Dissection. — The tendons of those muscles which are connected with the joint were not torn, and the capsular ligament was found attached to the coracoid j^rocess of the scapula. When the ligament was opened it was found that the head of the os humeri was situated under the coracoid process, which formed the upper part of the new glenoid cavity; the head of the bone appeared to be thrown on the anterior part of the neck of the scapula, which was hollowed, and formed the lower portion of the glenoid cavity. The natural rounded form of the head of the bone was much altered, it having become irregularly oviform, with its long axis from above down- wards : a small portion of the original glenoid cavity remained, but this was rendered irre- gular on its surface by the deposition of cartilage. There were also many particles of cartilaginous matter upon the head of the OS humeri, and upon the hollow of the new ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 591 cavity in the cervix scapulae, which received the head of the bone. At the upper and back part of the joint there was a large /jicce of the cartilage which hung loosely into the cavity, being connected with the synovial menlbrane at the upper part only by two or three small membranous bands. The long head of the biceps muscle seemed to have been ruptured near to its origin at the upper part of the glenoid cavity, for at this part the tendon was very small, and had the appear- ance of being a new formation.' — Signed, James Patey. "This accident," adds Sir Astley, "hap- pens from the same cause which produced the dislocation forward. The anterior part of the hgament is torn, and the head of the bone has an opportunity of escaping forwards to the coracoid process." * The foregoing dissection, which is illus- trated by an engraving in Sir A. Cooper's work on Fractures and Dislocations, should not, in our opinion, be considered in any other light than as an excellent specimen of the anatomical appearances to be found in those who have had chronic rheumatic ar- thritis of the shoulder joint ; for we consider that these appearances were not the result of an accidental luxation, but the true effects of this slow chronic disease. If Sir A. Cooper had known any thing of the history of the case during life, we might hesitate to call in question the opinion of so eminent an au- thority on such a subject ; but as the only grounds he possessed for forming any opinion were derived from the mere anatomical ap- pearances observed in the shoulder joint of the subject in the dissecting-room, we con- ceive that every one who studies the report of this dissection, accompanied as it is by an engraving, is at liberty to draw his own con- clusion as to what was the real nature of the case ; and to us it seems quite clear that the appearances observed in the examination of the case referred to by Sir A. Cooper were exactly those most frequently found to be the result of chronic rheumatic arthritis as it affects the shoulder joint. The new form assumed by the head of the humerus, the fact of the cartilage having been removed, and its place supplied by an ivory enamel — the piece of cartilage which hung loosely into the cavity being connected with the synovial membrane, at the upper part only, by two or three small membranous bands — the attachment of the capsular liga- ment to the coracoid process — all these cir- cumstances related in the above-mentioned case strongly remind us of what we now know to be characteristic marks of the disease we have denominated chronic rheumatic arthritis, as we have so often met with them. Add to this, the observation that the intra-ar- ticular portion of the long tendon of the biceps muscle did not exist ; or, as is pre- sumed, to have been " ruptured " at its origin. * See Sir A. Cooper on " Dislocations," p. 449. Plate 21. fig. 2. ; also octavo edition of this work by Mr. B. Cooper, p. 401. In all these details we find a very complete account of the anatomy of the shoulder joint which had been the seat of chronic rheumatic arthritis. On the other hand, such appearances afford no evidence whatever that an accidental luxa- tiori*was the cause of them ; certain it is that appearances exactly resembling those de- scribed in Sir A. Cooper's case have been met with in cases in which their cause could not be attributed to accident, because no in- jury had been received; while in others it was useless to refer to accident, inasmuch as the morbid action had similarly affected both shoidder joints ; so that by the dissection of such cases we have convinced ourselves that disease^ not accident, was the source of the morbid appearances. If the reader will com- pare the woodcut 429.), which is designed to represent the anatomical appearances pre- sented by the examination of a case (J.Byrne) already detailed, of chronic rheumatic ar- thritis of the shoulder, with the engraving of Sir A. Cooper's case of partial luxation of the head of the humerus, he will, we think, agree with us that the writer, in believing that whatever causes influenced the produc- tion of the morbid appearances in the one were identical with those which produced them in the other. Sir A. Cooper, in our opinion, somewhat gratuitously supposes that his specimen was the much sought-for ex- ample of the anatomy of the accident called partial luxation. We say gratidtoudy, because the previous history of the case he alludes to was unknown, and the accident siijiposcd to have occurred. In the case the writer has adduced (J. Byrne, (^fig. 429.), the history was known, and has been preserved, with the account of the post-mortem appearances which the examination of the shoulder joint presented. At the meeting of the British Association at Bristol in September, 1836, the author gave an account of this chronic rheumatic disease, as it engages most of the joints. When speaking of its effects on the shoul- der, he alluded to this case published by Sir A. Cooper ; and then demonstrated, as he thought, to the satisfaction of the meeting, that the specimen {Jig. 429.) of this chronic rheu- matic disease which he then laid before them for inspection, corresponded exactly to the ap- pearances found in the supposed case of " par- tial luxation of the humerus " delineated in Sir A. Cooper's work. The opinion which he at that time expressed (now twelve years ago) has since been amply confirmed by his subsequent experience *, and by the opportu- nities he has had of further investigating the nature of this disease. In the Museum Anatomicum'\ of Sandi- fort, 1827, we find dehneated the bones of the shoulder joint which present all the cha- * See Athenaeum, September 10, 1836 ; also Pro- ceedings of the Dublin Pathological Society, Dub- lin Joiu'nal, vol. xv. p. 502. t Vol. iv. tab. 24.^5. 1, 2, 3. 592 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. racters of the chronic rheumatic arthritis, with partial displacement upwards of the head of the humerus. Sandifort also, we feel sure, has fallen into the error of concluding with- out proof, that this specimen of the bones of the shoulder constituted an example of par- tial luxation from accident (" liixatio ossis humeri ab injuria externa'"). The subject of this case, he says, was a robust man: the head of the humerus having been driven upwards between the coracoid process and the acromion, a new articular surface was produced, partly on the upper narrow part of the glenoid cavity, and partly on the root of the coracoid process. This new articular surface, in its centre porous, was as to its circumference hard, pohshed, and ivory-like (" partim porosa sed caetera valde polita ac quasi eburnea"), and had been in habitual contact with the head of the humerus. The latter was much enlarged, and its circumference near the corona of the head was much increased by the addition of a hard rounded margin (" margine revoluto calloso"). The wearing away of the upper part of the great tuberosity, the eburnisa- tion of the summit of the humerus where it came in contact with the concavity of the coraco-acromial vault, the preternatural con- tact of the head of the humerus with the under surface of the acromial extremity of the clavicle, are also noticed. " Caput ossis humeri amplitudine auctum, margine revoluto calloso, in superficie articular! affert eandem prasternaturalem glabritiem et duritiem, dum in vertici, ubi tuberculum majus occurrit, superficiem exhibet partim glaberriraam, par- tim inequabilem, rugosam, quae juxta sum- mum humerum movebatur trituratione, etiam locum habuisse inter marginem inferiorem claviculse, et verticem capitis humeri mani- feste a[)paret ; subluxatio in superiora ergo hie locum habuit."* Here we find the description of the bones unaccompanied with any account of anatomi- cal characters of the other structures of the joints ; nor is there any proof adduced that any accident had occurred to produce the appearance noticed ; we may therefore, we think, conclude, that the history of the case was unknown. When we compare Sandifort's description of the above case, accompanied as it is with an engraving, with the account given by us in the preceding pages of the dissection of other cases of the chronic rheumatic ar- thritis as it affects the structures of the shoulder joint, we think we may safely con- clude that this case, adduced by Sandifort as an example of partial luxation of the head of the humerus upwards from external injury, must be considered as presenting in the bones described the anatomical characters of chro- nic rheumatic disease, as it very commonly affects the bone of the shoulder joint. In the anatomical examination of advanced cases of this disease of the shoulder joint, which we have witnessed, in which there * INIuseura Anatomicum Sandifort, tab. c\lfgs. 1, 2, 3. vol. iv. had been jiarlial luxation of the head of the humerus upwards — when the deltoid mus- cle has been cut through, the head of the humerus has been usually found exposed, and in absolute contact with the under surface of this muscle, having passed through the upper part of the capsular ligament. In such cases, the head of the humerus has been found to present the usual characteristic appearances of this chronic rheumatic disease ; that is to say, the cartilage has been absorbed, and its place supplied by an ivory-like enamel. The arti- cular portion of the tendon of the biceps has also been removed, as well as all those parts which in the normal state intervene between the summit of the head of the humerus and the under surface of the coraco-acromial arch. The superior portion of the capsular ligament itself has been found perforated ; and the under surface of the coraco-acromial vault excavated, and has become a new and sup- plementary socket for the head of the hu- merus {fig. 429.). The explanation of the circumstance why the su])erior and external part of the capsular liga- ment has been found perforated by a large cir- cular opening, through which the head of the humerus can pass, appears to be, that the effects of the loss of the tendon of the biceps are such, that the head of the humerus is at once elevated by the deltoid, and kept habitually pressed up against the under surface of the acromion. The coraco-acromial vault now becomes the articular socket for the head of the humerus, more than the original glenoid cavity. The head of the humerus assumes altogether a new form ; its summit is ex- panded, and at the same time smoothed by the constant effects of use and friction ; the anatomical neck is encroached upon, and gradually the whole summit, including the great and lesser tuberosities, becomes articu' lar, these latter eminences being, as it were, ground down and covered with a porcelainous deposit (^fig. 428.). As the upper portion of the circular groove, called the anatomical neck of the humerus, which normally gives attachment to the capsular ligament of the joint, has been removed, this attachment of the capsule must be destroyed, and a large opening will be found in it. This occurrence is well illustrated by a case of chronic rheu- matic arthritis of the shoulder joint, described by Mr. Hamilton Labatt, who entitles the case, *' An excellent specimen of that chronic disease of the shoulder joint which old people are liable to ; as also an example of partial luxation upwards, the result of slow disease." * The history of this case, as of almost all of the same kind published, was unknown. The subject was a female aged GO, brought into the College of Surgeons for dissection ; the muscular system well developed. The com- mon integuments had been removed when Mr. Labatt was called to witness the dissec- * Vide London Medical Gazette, 1838, vol. xxii. p. 22. ; also Catalogue, Coll. Surgeons, Ireland, vol. ii. p. 396. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 593 tion, and the deltoid muscle was cut across and thrown back, when the attention of the dissector was attracted b}' the head of the humerus, which was exposed and firmly sup- ported against the under surface of the acro- mion process by the lips of a vertical rent in the capsular ligament, which was otherwise healthy, firmly girding the anatomical neck of the humerus. The articular cartilage of the head of the humerus had been universally eroded. The head of the humerus had been increased in size by the addition of an osseous margin, which overhung the anatomical neck of the humerus. Several cartilaginous bodies, connected to the surrounding fibrous tissues, projected into the cavity of the joint. The larger were pedunculated and pendulous, while the smaller were attached by broad sur- faces. The articular part of the biceps tendon had disappeared. The capsular ligament was thickened ; and the longitudinal aperture al- ready mentioned, which existed in the upper part, was sufficiently capacious to allow the head of the bone under certain circumstances to pass with facility from its natural situation upwards, and to come in contact with the under surface of the acromion process. The coraco-acromial articulation of the same side, as well as several of the other articulations in this subject, exhibited unquestionable traces of having been affected with the same dis- ease.* When a specimen of chronic rheumatic ar- thritis of the shoulder joint, such as the pre- ceding, has been met with, by anatomists not familiar with the ordinary anatomical charac- ters of the disease, it is usually mistaken for a case of partial displacement of the humerus upwards, the result of accident. We find many such cases and such mistakes recorded. Although the history of Mr. Labatt's case was unknown, the ap[)earances which the head of the humerus presented were sufficiently cha- racteristic to clearly designate the true nature of the affection, independently of the condi- tion alluded to of the coraco-clavicular and other articulations, so many concurring cir- cumstances sufficiently proved that, in the above case, the shoulder had been long affected by the chronic rheumatic arthritis, and that this, and not accident, was the source of the partial luxation upwards which existed. In April, 1840, Dr. Robert Smith, who is well acquainted with this disease, laid before the Surgical Society of Dublin an account of the post-mortem examination he had made of an aged female, who died of an internal organic disease in the House of Industry. She had been long affected with a partial displacement upwards of the right humerus, which was the result of chronic rheumatic disease. He pre- sented a cast of the upper part of the body, taken after death, showing the degree of ele- vation of the summit of the humerus on the affected side; and also exhibited a prepara- * This specimen is presers'ed in the ^Tuseum of the College of Surgeons. Vide Catalogue, Coll. Surg. Ireland, vol. ii, p. 396. VOL. IV. tion of the shoulder joint to the meeting. The post-mortem examination had been made a few weeks previously to Dr. Smith's com- munication of this case to the society. " It may be seen," he said, '* from the cast, that in this case there was a remarkable contrast in the appearance the two shoulder joints pre- sented : on one side, the head of the hinnerus was placed far above the level of the coracoid and acromion processes. Many persons," he added, " in viewing the cast and accompanying preparation, might consider the specimen as one of some unusual form of congenital mal- formation, or the result of accident ; but the abnormal appearances were clearly the result of that peculiar affection of the joints, of which so many specimens had been elsewhere brought forward by the president in the chair (Mr. Adams), and which disease he has denominated * chronic rheumatic arthritis.'" Dr. Smith added that his chief reason in bringing forward the case was, that it pre- sented some peculiarities he had not observed in other specimens of the same disease, as it affects the shoulder joint : he had often before noticed the elevation of the head of the bone as a symptom of this affection, but had never seen the elevation to the same degree it had amounted to in this case. The head of the humerus was displaced upwards, even to a point above the level of the clavicle and acro- mion process. The capsular ligament was enlarged, and as thin as if the synovial mem- brane alone constituted it. Superiorly, this capsule was altogether deficient : a large aper- ture was here found, which permitted the head of the humerus to pass upwards, as already mentioned ; the tendon of the biceps was perfect, but was thrown off the head of the bone inwards. The cartilage of the head of the bone was abraded in several places, and osseous depositions had been formed in the vicinity of the bicipital groove, and around the margin of the articular head of the humerus, as is usually the case in examples of chronic rheumatic disease. Mr. Smith observed, that the preparation s'lowed a large deficiency in the upper part of the capsular ligament — a fact not before observed by him, until he had seen Mr. Labatt's preparation ; and even then he was disposed to attribute the deficiency to some injury received in removing the parts. He had therefore taken the greatest care in removing the preparation just exhibited to the society, and had found that in dividing the deltoid muscle he had cut at once into the cavity of the joint. Dr. Smith and the writer have lately care- fully examined this preparation, and find that the acromion process has been nuich reduced in thickness ; its under surface is excavated, and denuded of all periosteal covering ; this process is divided into two portions, as if a fracture had traversed the original line of the junction of the epiphysis with the rest of the process : half an inch in extent of the bone is thus separated from the rest, and seems merely retained by a ligamentous connection. The deltoid and triangular ligament were 594 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. relaxed : — " The shoulder joint presented a remarkable degree of mobility in this case ; and the head of the humerus of the affected side could be pushed half an inch higher than its fellow." The great peculiarity in this case Dr. R. Smith thought consisted in the cir- cumstance that the tendon of the biceps was not, as it usually is in cases of this chronic disease, absorbed, but was in a perfect state of integrity as to structure. This tendon having been thrown off the head of the humerus, and displaced inwardly, its normal function to restrain the ascent of the humerus, through the mediuin of its mus- cular connection, was as much annulled as if it had been removed altogether, as it usually is, under the influences of this chronic dis- ease. Questions here naturally arise : Can the tendon of the biceps be dislocated from its groove by accidental violence ? and if so, Shall the consequent dislocation of the head of the humerus be in the direction upwards, exactly as it was in the preceding case, which was evidently an example of the displacement of the tendon from disease. Mr. John Soden, junior, of Bath, has pub- lished a case, accompanied by some interesting remarks, the objects of which are to prove that the tendon of the biceps may be dislocated by accident, and that a partial displacement of the head of the humerus upwards must im- mediately follow. Mr. John Soden'' s case. — Partial disloca- tion 2ipwards. — " Joseph Cooper, aged 59, was admitted into the Bath United Hos- pital, November 9, 1839, on account of a compound fracture of the skull. His death afforded an opportunity of examining an old injury of the right shoulder, the symptoms of which had been always involved in great ob- scurity, and which occurred in the following manner : — *' In the month of May, 1839, the deceased (six months before his death) was engaged in nailing down a carpet, when, on rising sud- denly from his occupation, his foot slipped, and he fell backwards on the floor. In order to break the force of the fall, he involuntarily placed his arm behind him, and by so doing received the whole weight of the body upon his right elbow ; that joint, the only one struck, received no injury, for the shock was instantly transmitted to the shoulder, and there the whole effects of the accident were sustained. Acute pain was immediately ex- perienced, and the man supposed he had either suffered a fracture or a dislocation, but finding that he cotdd raise the arm over his head, he felt reassured, and endeavoured to resume his work. The pain, however, com- pelled him to desist, and he went home." " When I saw him," says Mr. Soden, " on the following morning, the joint was greatly swollen, tender to the touch, and painful on very slight motion. There was then no pos- sibility of his placing his arm over his head, as he had done immediately after the acci- dent. I satisfied myself that there was nei- ther fracture nor dislocation of the bones, and not suspecting the existence of a more specific injury than a severe sprain, I set down the case as such, and avoided the un- necessary pain of further examination. Un- usually active means were necessary to sub- due the inflammation, and at the end of three weeks, though the swelling was much reduced, the tenderness in the front of the joint, and pain on certain motions of the limb, were scarcely less than on the day after the occurrence of the accident. " On comparing the joint with its fellow, now that the swelling had subsided, a marked difference was observable between their re- spective outlines. The injured shoulder was evidently out of drawing, but without pre- senting any glaring deformity : when the man stood erect with his arms dependent, the dis- tinction was very manifest, but difficult to define. There was a slight flattening on the outer and posterior part of the joint, and the head of the bone looked as it were drawn up higher in the glenoid cavity than it should be. Examination verified the appearance in two ways : first, on moving the limb, with one hand placed on the shoulder, a crepitating sensation was experienced under the fingers, simulating a fracture, but in reality caused by the fric- tion of the head of the humerus against the under surface of the acromion : secondly, on attempting abduction, it was found that the arm could not be raised bej'ond a very acute angle with the body, from the upper edge of the greater tubercle coming in contact with that of the acromion, and thus forming an obstacle to all further progress. The head of the bone was also unduly prominent in front, almost to the amount of a partial dislocation. For all useful purposes the arm was power- less. The pain caused by the action of the biceps was acute, extending through the whole course of the muscle, but felt chiefly at its extremities. When the joint was at rest the pain was referred to the space in front, be- tween the coracoid process and head of the humerus ; which spot was marked by extreme tenderness and some puffy swelling. *' The patient being of a rheumatic habit, in- flammatory action of that character was soon established in the joint, so that the peculiar symptoms of the injury were marked by those of general articular inflammation, which added greatly to the man's suffering, and to the dif- ficulty of diagnosis. On examining the joint the accident was found to have been a dislo- cation of the long head of the biceps from its groove, unaccompanied by any other injury. The tendon was entire, and lay enclosed in its sheath, on the lesser tubercle of the hu- merus ; the capsule was but slightly ruptured ; the joint exhibited extensive traces of inflam- mation ; the synovial membrane was vascular and coated with lymph ; recent adhesions were stretched between different parts of its surface, and ulceration had commenced on the cartilage covering the humerus, where it came in contact with the under surface of the acromion ; the capsule was thickened and ad- ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 595 herent, and in time, probably, anchylosis might have taken place." Observations on this case. — In this interest- ing case, recorded by Mr. Soden, it is true that the tendon of the biceps was dislocated; but, we may ask, are the appearances noticed during life, as well as the condition of the shoulder joint found on examination after death, capable of any other explanation than that given to them by Mr. Soden ? L^'pon such a matter we feel we ought to speak with the greatest diffidence, because this case is so far unlike almost every case of partial luxa- tion yet published in this circumstance, that its history was known before the post-mortem examination of the joint was instituted. However, we must confess that we do not as yet feel convinced that the case of partial displacement upwards of the head of the hu- merus, as the immetliate and direct result of accident, has been fully proved by Mr. Soden. If we analyse the symptoms the patient him- self reports to have observed immediately after the accident, we find that he at first supposed he had either suffered a fracture or a dislocation, but finding that " he could raise the arm over his head^^ he felt re-assured, and endeavoured to resume his work. It would appear to us, ihat if the tendon of the bi- cej;s were accidentally dislocated the patient would not be able, immedi tely after the acci- dent, to raise his arm over his head ; while the circumstance here noticed seems quite reconcilable with Mr. Soden's own impres- sion, that there was in this instance no other injury than a severe sprain of the joint. The symptoms under which the patient subse- quently laboured were those of an inflamma- tory character, such as might have been expected where so severe a sprain had oc- curred, as we may suppose the shoulder joint in this instance to have suffered. The ap- pearance the joint presented externally when the disease became subacute, or chronic, namely the flattening of the outer and poste- rior part of the joint, and the appearance of the head of the bone, which had been drawn up higher in the glenoid cavity, the crepitating sensation caused by the friction of the head of the humerus against the under surface of the acromion, the pain felt in the whole course of the biceps muscle, the difficulty experienced in abduction of the elbow from the side, the prominency of the head of the bone in front, almost to " the amount of a partial disloca- tion,"— all these symptoms we have repeatedly noticed to belong to the affection of the shoul- der joint which w^e have called chronic rheu- matic arthritis, and all these have been present in patients who have had this disease in both shoulder joints at the same time, and in whom they could not by any means be referred to accident. Finally, before we leave our anal\- sis of the symptoms of this case, we must not omit to allude to the author's own observa- tion— " The patient being of a. rheumatic habit, inflammatory action of that character was soon established in the joint, so that the peculiar symptoms of the injury were masked by those of general articular inflammation, which added greatly to the man's suffering, and to the difficulty of diagnosis." The patient being, as we are tokl, of a rheumatic habit, or [)redisposcd to this ar- ticular disease, it may be readily conceived that any injury this man, aged fifty-nine, might receive in the shoulder joint would be well calculated to give rise to the disease which we have calied chronic rheumatic arthritis. As to the anatomical examination of the joint, it will be recollected that the disease had been only six months established, and there'bre that the more striking results of chronic rheumatic disease should be found was not to be expected. Those which were noticed, however, were such as might be sup- posed to represent the anatomical characters of chronic rheumatic arthritis of the shoulder in an early stage. As to whether Mr. Soden's interpretation of his own case be the correct one, or the doubt we have ventured to express should be considered to have a just foundation, we must leave to the judgment of others, to time, and to the result of future investigations to determine ; but the subject must be con- fessed to be one of a truly practical nature, and therefore worthy of further inquiry. We had written thus much on the subject of partial dislocation of the head of the hu- merus upwards, with displacement inwards of the long tendon of the biceps, when (on the 12th of August, 1848) an opportunity occurred to us of examining anatomically both shoulder joints of a patient who had died in the North Union Poor House the day before, who had been for eight years one of the severest sufferers the writer had ever known from chronic rheumatic arthritis in almost all his joints. The disease existed in an aggravated form in his hips and knees, wrists and elbows, and of late years began also to affect equally both shoulder joints. It was very remark- able that, on examining anatomically the shoulder joints in this case, we discovered the same displacement of the head of the humerus upwards, with dislocation of the tendon of the biceps inwards, as in Mr. So- den's case, in both shoulder joints, and with the dislocation of the long tendon in both shoulder joints in this case, which we shall now relate, were found associated the ordinary anatomical characters of chronic rheumatic arthritis in rather an early stage of the disease; while in the other articulations of this same individual the chronic rheumatic disease was in a very advanced state. Case. Charles Mailly, aetat. 48, had been a farming servant in the country,and was remark- able for his strength and activity. He was addicted to drinking ardent spirits to excess, and it was stated of him that he frequently lay whole nights in the open air in a state of insensibility from drunkenness. To these circumstances he attributed the origin of his disease, which disabled him from earning his bread ; he was therefore admitted into the poor house, in 1840. For the last five years he Q Q 2 596 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. has been altogether confined to his bed, as he could not stand upright, much less walk, when the writer visited him in August, 1847. His hips, knees, and elbow joints were semiflexed and rigid, his wrist extended, his fingers and toes presented the ordinary characteristic distortion belon<:ing to rheumatic gout, or chronic rheumatic nrtliritis.* Although the shoulder joints in this case had lost much of their muscular covering, the deltoid and cap- sular muscles being in a state of atrophy, yet the bones of the articulation seemed much enlarged, and the heads of both humeri were evidently situated much above the level of the coracoid process. He did not complain of much pain in the shoulders ; the constant torture he endured in the right hip and both his knees quite distracted his attention from all minor suiiering. He stated that he had a " crackling " sensation in all his joints when- ever they were moved ; that his sufferings were influenced by the weather, and that he endured more pain during the frost of winter than at any other time. The patient died worn out by pain and irritative fever, attended with severe diarrhoea. Post-mortem exam'motion. — Dr. R. Smith assisted the writer in this examination. As the body lay on its back on the table, the hips, the elbows, and knee joints were semi- flexe 1, and could not be extended, but they permitted of flexing to a very trivial degree. AVhen any of the affected joints were moved, the characteristic crepitus, or crackhng, so often alluded to, was elicited now as during life. The head of the os humeri of each side was drawn up much above the level of the coracoid process, and was preter- naturally advanced. LTpon rotating the hu- merus, a marked crepitus was evident in these as well as all the other joints. On re- moving the integument over the right shoul- der joint, the deltoid muscle was found pale, and forming a thin attenuated layer of muscular fibres covering the articulation. When this was removed, the sub-deltoid bursa was seen to be of a yellowish colour, and it had a fibrous appearance externally, like to a capsular ligament. When this bursa was freely cut into by an incision parallel to the margin of the acromion, its cavity was observed to be more capacious than usual. The posterior or inferior wall of the bursa was found to have identified itself with the external and superior part of the fibrous capsule of this articulation, and both seemed here to have become degenerated into thin cellular structure, which adhered to and formed a periosteal covering for the summit of the humerus near to the upper part of the great tuberosity. The capsular ligament was elsewhere somewhat thicker than natural, particularly at the upper and anterior part, where it seemed to have identified itself at its origin with the coraco- humeral ligament, which was much thickened. As to its attachment to the humerus, the * See Haxd, Yol. 11. p. 518. rig. 233. capsular ligament, superiorly and posteriorly, was very siiort, having become adherent to the head of the bone before this capsule had reached its usual point of insertion into the anatomical neck of the humerus. Ante- riorly and interiorly the capsule descended on the neck of the humerus btlow its normal level {fig. 430.). When this ligament was cut into and examined posteriorly, several broad patches of adhesion were found to exist (as in Mr. Soden's case) between its internal surface and the head of the bone pos- teriorly, so that in these parts the syno- vial cavity was completely obliterated by the adhesion of the opposed surfaces of the membrane which lined the capsular liga- ment, and invested the posterior part of the iiead of the humerus, just as we find occa- sionally the pericardium partially adherent to the surface of the heart. When the capsular ligament was fully opened anteriorly, where it is covered by the tendon of the subscapu- laris, it was seen, more evidently than it could have been previously, that the head of the humerus had been placed habitually above the level of the coracoid process and the highest point of the glenoid cavity from which the long tendon of the biceps springs {fg. 430.). The tendon of the biceps lay entirely to the Fig. 430. Case of Charles Mallly. — CJironic rheumatic arthritis. The louci tendon of the biceps dislocated inicards, the head of the humerus partially displaced up- wards, as in Jlr. Soden's case. . inside of the head of the humenis ; indeed, such was its position, that it might rather be said that the humerus was displaced out- wards, and elevated above the level of the course of the tendon of the biceps, than that the latter was dislocated inwards. A semi- circular groove marked the course of the tendon of this muscle as it arched across from the highest point of the glenoid cavity to the summit of the bicipital groove. The portion of the head of the humerus which was situated ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 597 above the course of the tendon of the biceps was divested of all cartilaginous coverini;, was of a yellowish colour, and remarkably hard, and presented an appearance as if the summit of the humerus had been prepared for the polish of eburnisation, but as yet no ivory-like enamel had formed, because as yet bone had not come in contact with bone. The head of the humerus was much en- larged and altered from its normal figure, par- ticularly above, in the neighbourhood of the great tuberosity, which bulged out much ex- ternally ; the usual deep groove above, sepa- rating the tuberosity from the head, and here marking the anatomical neck of the humerus, was effaced. The under surface of the neck of the hu- merus was furnished with a vast number of the synovial fimbriae before noticed by us when describing the anatomical characters of chronic rheumatic arthritis of the shoulder and other articulations. * These were in the recent state of a very red colour. The humerus seemed habitually to have remained in contact with the glenoid cavity, rotated inwards, and in this position these synovial fimbriae lay in contact with the inferior and broadest part of the glenoid cavity ; and it was very remarkable that wherever these red sy- novial fimbriae had been in exact apposition with the cartilage of incrustation of the gle- noid cavity, exactly in the extent of the con- tact the cartilage had been removed, satisfac- torily proving that these vascular fimbriae had been absorbing villous surfaces. The glenoid articular surface presented but little worthy of notice, except a porous ap- pearance where its cartilaginous investment had been removed by the absorbing vilH, and the commencing state of disintegration of the glenoid ligament. The cartilage which re- mained on a portion of the head of the hu- merus, as well as that which still adhered to the surface of the glenoid cavity of the sca- pula, was rough, and altered from its natu- ral state. The acromio-clavicular articula- tion of this side seemed enlarged externally, the periosteum about it thickened. When the articular surfaces were exposed, it was found that the cartilaginous covering had been re- moved, and that the articular surfaces were nearly double their normal size. It is quite plain that the movements of the head of the humerus in the glenoid cavity in this case had been confined to those of a species of sem.i-rotation only ; the adhesions which were found to exist between the head of the humerus and the inner surface of the synovial membrane of the joint sufficiently suggest this, as well as the new form which the head of the humerus had assumed. The left shoulder joint in almost every re- spect was symmetrically affected with the right, but particularly as regarded the dis- location of the tendon of the biceps, the ex- istence of fimbriae, &c. &c., and therefore it does not require a separate description. * See Dublin Journal, vol. xv. p. 159. It does not appear to us necessary to enter into any details here, relative to the condition the other articulations were found in. The lungs and other viscera were sound. Whether the patient ever had rheumatic fever or not we are not now able to learn ; but we may mention that upon looking to the state of the heart j'.nd its membranous coverings we found the peri- cardiunj adherent to the heart on all its sur- faces except where it lay on the diaphragm. It seems to us plain that hereafter, when the tendon of the biceps shall be found displaced interna!!}', we are not at once to refer the dislocation to accident, but that inquiry must be made as to whether chronic rheumatic arthritis may not have been its cause. That the tendon of the bicej^s should, under the influence of changes which the structures of the joint may have undergone from disease, be thus thrown off the head of the humerus over which it arches, does not appear to us extraordinary, because we have known similar displacement of tendons under analogous circumstances ; indeed, we have generally found the extensor tendons of the fingers displaced, and the ligament of the patella and patella itself are sometimes thrown on the outer side of the external condyle of the femur when the knee joint has been the seat of chronic rheumatic arthritis. In Mr. Soden's case accident may have had just so much to do with the displacement of the tendon, that the injury was the inmiediate exciting cause of the development of a local disease, a predisposition to which had pre- viously existed in the constitution of the patient. The writer regrets much that he has not as yet had any opportunity of examining the preparation of the shoulder joint presented by Mr. Soden to the museum of King's Col- lege, London ; but he requested his friend Dr. Macdowell, at the time in London, and who was familiar with the many preparations of chronic rheumatic arthritis contained in the Richmond Hospital Museum, to report to him his opinion on the appearances the pre- paration presented, and he writes to say, " that from the partial examination he could make of the preparation he had only to re- mark, that the head of the humerus is con- siderably enlarged, and that the long tendon of the biceps, which has been dislocated in- ternally, is in a state of atrophy." In these two additional circumstances, as well as those already mentioned, the preparation resembles those of the shoulder joints in the case of Mailly. Although we have as yet said but little of any displacement of the head of the humerus occurring as a consequence of this chronic rheumatic disease, except in the di- rection upwards, and upwards and inwartls, yet we would now call attention to facts to prove that the head of the humerus, un- der the influence of the changes induced by this disease in the structures of the shoulder joint, may suffer a partial displacement di- rectly inwards under the coracoid process ; Q Q 3 598 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. partially downwards, enlarging the axillary margin of the scapula, so as to form a new glenoid cavity ; and lastly, that the infra-spi- natus fossa of the dorsum of the scapula may become the new situation, to which the head of the humerus may be transferred from the effects of chronic rheumatic arthritis of the shoulder. The writer has after much investigation seen but two examples of this last displace- ment, and, curious to observe, these were in the rii>ht and left shoulder joint of the same indivitlual. Partial dulocation of the head of the humerus hiwards. — In the museum of the College of Surgeons, Dublin, we find a specimen pre- sented by Professor Hargrave, which he con- siders one of ])artial luxation inwards from accident. The accidental origin of the af- fection, however, cannot be proved, as the history of the case is unknown ; and the spe- cimen presents so many of the features of the chronic rheumatic disease combined with the partial luxation, that we are of opinion that Professor Hargrave's specimen cannot be considered the result of accident ; but that all the appearances it presents are the conse- quence of long established chronic rheu- matic arthritis. We shall here give an ab- stract of Dr. Hargrave's case, referring for a fuller account to the Edinburgh Medical Journal. The capsular ligament presented a perfect state of integrity along the superior and pos- terior part of the joint. It was very dense and strong, extending from the acromion process downwards and forwards towards the humerus. When the capsule was opened on its internal aspect, the head of the humerus was seen to be in part external to the joint, and was di- vided into two unequal portions by a deep groove extending for the entire length of its head in a perpendicular direction. Of these two portions the internal and larger one passed a small distance beyond the corre- sponding edge of the glenoi(i cavity into the subscapular fossa, while the posterior and smaller one remained in the glenoid cavity, occupying its internal surface. The groove now mentioned fitted on the inner edge of the glenoid cavity, which did not present its usual well defined border, but was rounded off", so as to present a thick lip, from the constant pressure and frequent mo- tion of the humerus upon it. The head of the humerus in its superior aspect was in close a[)position with the coracoid process, and had altered in a remarkable degree its form, which in place of being beaked and point- ed, was much expanded^ flattened and slightly hollovved. When the articulation was first opened, the tendon of the long head of the biceps could not he seen ; but on more particular examina- tion it was found to have been rujHured, the portion connected with the muscle being in- timately attached to the bicipital groove of the humerus, while the portion belonging to the glenoid cavity was much diminished in size. and presented a mere rudimental character in the capsular cavity.* When we carefully observe this specimen, we notice that it presents many of the general anatomical characters of the chronic rheumatic arthritis, these appearances being of course modified, as to the external shape of the sur- faces, by the special peculiarity of the partial displacement which had in this case occurred. The head of the humerus was much en- larged and mis-shapen. It was found that a large portion of the new articular cavity for the head of the humerus lay on the sub- scapular fossa, but that a portion of the old glenoitl cavity remained, and that the head of the humerus, divided into two surfaces, arti- culated with both the new and old glenoid cavity. The effects of friction during the movements which took place between the bifid head of the humerus and the double articular cavity, which corresponded to it, were such that perfect and complete ebur- nisation of parts of the contiguous surfaces took place. This last circumstance could not be said to amount to proof, that chronic disease rather than accident had caused the partial luxation. In addition to the ivory-like enamel, we find also that bony vegetations, or granular nodules of new bone, surround the out- line of the new articular surface formed for the head of the humerus; and that small foreign bodies, like sesamoid bones, are seen bordering the edge of the articular cavity posteriorly. All these minor circumstances remind us of the anatomical characters we have found in examining cases of chronic rheumatic arthritis of the shoulder. Tiie coracoid process, we are informed, had altered in a remarkable degree its form, which had become expanded, flattened, and slightly hollowed; in a word, it became articular, as we have often before found it to be, as the result of chronic rheu- matic arthritis. The glenoid ligament (Pro- fessor Hargrave's case) was absent ; and the following description, which we may be ex- cused for recopying, may well be applied, we think, to the ordinary condition of the tendon of the biceps in most of the cases of chro- nic rheumatic arthritis of the shoulder. " When the articulation was first opened, the long tendon of the biceps could not be seen, but on more particular examination it was found to have been ruptured, the portion con- nected with the muscle being intimately at- tached to the bicipital groove of the humerus, while the portion belonging to the glenoid cavity was much diminished in size, and pre- sented a mere rudiment." We have already made the remark, that when the shoulder joint is the seat of chro- nic rheumatic arthritis, the neighbouring acromio-clavicular articulation is frequently affected with this same disease. Now, in care- fully examining Professor Hargrave's specimen, we shall find that not only do the anatomical characters which belong to chronic rheumatic * See Catalogue of the Museum of the R. C. of Surgeons, Dublin, vol. ii. p. 397, Edinburgh Medical and Surgical Journal, for October, 1837. AB^'OIlMAL CONDITIONS OF THE SHOULDER JOINT. 599 arthritis exist in this shoulder joint, but also that the acroniio-clavicular articulation in the same specimen is enlarged externally; and that, on examining it internally, it presents undoubted traces of this chronic rheumatic disease. Upon the whole, therefore, we feel convinced that this specimen produced by Professor Hargrave as an example of a case of partial luxation inwards, the result of acci- dent, does notreallyaffbrdany proof that exter- nal injury was the cau-se of the partial luxation. In thus differing from Professor Harirrave, we would make the same remarks which we have already made in allusi< n to Sir A. Coo- per's case, at page 59 1 . of this article. The pro- gress of science will soon settle the question. Partial displacement of the head of the hu- vwriis doicnwards has been observed to be the result of chronic rheumatic disease of long standing ; but after much diligent inquiry in museums and in books, I can find but two well-marked specimens of this morbid change. The most remarkable of these specimens is a left scapulo-humeral articulation, which is contained in the museum of the College of Surgeons, Dublin. The history of the case is unknown : the preparation formed part of the collection presented by Dr. Kirby to the College of Surgeons in Dublin. The head of the left humerus in this specimen is greatly enlarged, and a proportionate glenoid cavity has been formed to receive it. The head of this bone had descended so much beneath its ordinary situation, that a new glenoid cavity had been formed to receive it on the axillary border of the scapula. The lower part of the old glenoid cavity was still partially occupied by the enlarged head of the humerus, but the new addition to the cavity extends down- wards for the space of an inch and half below its ordinary situation. The new glenoid cavity is enamelled on its surface, and en- larged on its posterior margin by several irregular-shaped bones of new formation. The capsular ligament in this case has been partly ossified.* If we look over the engravings in Sandi- fort's Museum Anatomicum, we shall find, we think, a specimen of partial displace- ment of the head of the humerus downwards, the result of this chronic rheumatic dis- ease. The writer of the catalogue considers the specimen to have been the result of acci- dent, and has appended a history to the case, giving an account of somewhat equivocal symptoms. Whether these symptoms, — such as extensive elfusion into the cavity of the joint, of crepitus having been felt on the mo- tions of the bones on each other, — were the re- sult of accident or of disease, their origin is re- ferred to accident. When we carefully compare the engraving with what we have seen of other specimens of this disease elsewhere, we must, we think, come to the conclusion, that this * See Catalogue of the Museum of the College of Surgeons, Dublin, pp. 406 — 905. &c. See also plate IX. fig. 7. of a work on clironic rheumatic arthritis, shortly to be published by the writer ; illustrated by lithographic dravvings of natural size. example adduced by Sandifort must be con- sidered as the result of chronic rheumatic Fig. 4.31. Scapula and portion of the clavicle connected to it, viewed externally.* a, glenoid cavity ; h, a fragment of bone appa- rently of new formation ; c, anterior part of acro- mion separated from the spine of the scapula and re- united to it ; d, extremity of the coracoid process ; e, clavicle adhering to the acromion broken off from the spine of the scapula. The acromion process was depressed, and "omnem motum claviculae seque- batur." ( After Sandiford.) arthritis of long standing, with partial displace- ment of the altered head of the humerus down- ivards (fg. 431.). Upon looking at the wood- cut we notice the acromio-clavicular ar- ticulation enlarged as if from chronic rheu- matic disease. The acromion process is divided into two portions : a phenomenon we have so frequently noticed to accompany this disease of the shoulder joint (see p. 587.). We also notice the additional portions of bone of new formation attached to the capsular ligaT.ent so common in this disease, and the addition of an osseous margin to the glenoid cavity ; all these circumstances, so well seen in the origi- nal drawing to be found in Sandifort's work as large as nature, w e have attempted, in a re- duced form, to repeat here. Finally, the head of the humerus may be not only displaced partially upwards as' the result of this chronic rheumatic disease, par- tially inwards, and, as we have just proved, also partially downwards, but the most re- markable abnormal appearances the w riter has witnessed from this chronic disease, has been in two specimens contained in the Museum of St. Bartholomew 's Hospital, in which it will be found that the head of the humerus, w hich had been affected by this chronic disease, w as thrown completely backwards on the dorsum of the scapula. In this case the di>placement was double, and two new glenoid cavities had * Diminished drawing from one in Sandifort's Museiim Anatomicum, vol. iv. table 25. fig. 2. Q Q 4 600 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. been formed for the reception of the enlarged heads of the humeri behind the glenoid cavi- ties, and partly beneath the bases of the spines of the scapulae just where the head of the humerus has been found to rest in the ordi- nary dislocation backwards from accident ; but in this case, although the history was unknown, that these appearances were not the result of accident is almost certain, as similar abnormal appearances are ob- servable on each side. The notice of this preparation in the catalogue of the museum is as follows (p. 108—32.) : — " The bones of both the shoulder joints of an adult. In each joint there has been * ulceration,' or such absorption as occurs in chronic rheumatism of the articular surface of the head of the humerus, and the glenoid cavity. The heads of the humeri are flattened and enlarged by growths of bone awund their boi'dcrs; and the glenoid cavities, enlarged in a corresponding degree, and deepened, extend backwards and inwards to the bases of the spines of the scapulae. The articular surfaces, thus en- larged, are mutually adapted, and are har- dened, perforated, and in some parts polished and ivory-like. The changes of structure are symmetrical, except in that the articular surfaces of the right shoulder joint are more extensively polished than those of the left." Section II. — Accident. — The principal accidents the shoulder joint and the bones in its immediate vicinity are liable to, arc frac- tures and luxations. Fractures. — A fracture may traverse the acromion, the coracoid process, or detach the glenoid articular portion of the scapula from the body of this bone by passing directly across the neck of the scapula. A. Fracture of the acromion process. — A fracture of the acromion process maybe caused by the fall of a heavy body on the superior surface of the acromion ; but this accident most usually occurs in consequence of falls in which the patient is thrown from a height on the point of the shoulder. The fracture of the acromion will be generally found to have taken place at a point behind, and within, the junction of the clavicle with this bony process ; its direction we always observe to be in the original line of the junction of the epiphysis with the rest of the bone. In this accident, if the distance be measured from the sternal end of the clavicle to the extre- mity of the shoulder, it will be found lessened on the injured side. Considerable ecchymosis of the shoulder may be expected soon to suc- ceed the injury, and the patient will be unable to elevate the arm. Sometimes the perios- teum of the acromion is not torn, and then, although the fracture of the bone has been complete, there is no displacement of the fragments. If, however, this fibrous invest- ment of the acromion, above and below, be completely torn across, the acromion process will be found to be depressed, because it vvi.l be pulled down by the weight of the extremity and contraction of the deltoid muscle. The poriion of the acromion thus detached is generally very moveable, following the clavicle whenever the arm is moved. This accident is best recognised by the surgeon first taking hold of the elbow of the affected side, and elevating the whole arm perpendicularly. " Having thus restored the figure of the part, he places his hand upon the acromion, and rotates the arm, when a crepitus can be dis- tinctly perceived at the point of the spine of the scapula." * Fractures of the acromion unite by bone, sometimes with much deformity, arising from ossific depositions, which however do not, after a time, interfere much with the motions of the arm. This union has sometimes been known to take place in forty-eight days, and in other cases in a much shorter time. The union, however, is frequently only ligamentous. Sir A. Cooper speaks of a false joint being occasionally the result of a fracture. Mal- gaigne, alluding to a case in which a false joint was the consequence of a fracture of the acromion, says that the fractured surfaces presented a polished appearance, and were covered with an ivory deposit, the effects of friction. He adds, that the union was not simply a ligamentous connexion, but that an arthrodial false joint had been formed. In all the specimens of this fracture examined by Malgaigne, the suiierior border of the fracture was surmounted with small bony crests of new formation, of which the more consider- able number grew from the scapular portion of the acromion, while those produced from the detached extremity of this process were but few, no doubt inconsequence of its lesser degree of vitality. This remark of Malgaigne coincides with the observations to be found in Sir Astley Cooper's Work, that the dis- position to ossific union is very weak in the detached acromion. Malgaigne, however, re- fers to a preparation in the Museum of Du- puytren, in which the external fragment pos- sessed a thickness almost double that of the portion of bone from which it had been de- tached. This thickness the writer of the Catalogue of the Museum thought was caused by an overlapping of the fragments of the broken portions ot the acromion ; but Malgaigne supposes it to have arisen from simple hyper- trophy of the detached fragments. B. Fracture of the coracoid process — is a rare accident, and when it does occur, it is generally the result of a severe injury, in which the fracture of the bone is the least of the evils attendant on the compound injury. ThusBoyerf gives us the account ofafracture of the coracoid process produced by the blow of a carriage pole ; the patient died in a few days afterwards, in consequence of the severe contusion he suffered at the moment of the accident. The coracoid process, when frac- tured at its basis, is pulled downwards and forwards by the lesser pectoral coraco-bra- chialis and short portion of the biceps muscle. We are told \ that if the contusion accom- panying this accident be slight, we can seize * Sir A. Cooper. f Maladies Chirurgicales. % Sanson. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. GOl the fragment between the finger and thumb, and prove at once the mobility of the frag- ment and the existence of crepitus. If, says Boyer, the soft parts were in the natural state, we could easily recognise the fracture of the coracoid process, when it has occurred ; but so much force is necessary to produce this fracture, that the considerable swelling w hich always accompanies it, prevents us from being able to recognise the characters of the injury, so that it is not generally as- certained except in the dead body. C. Fracture of the neck of the scapula. — By a fracture of the neck of the scapula is meant a fracture through the narrow part of the bone immediately beneath the notch on the coracoid margin of the scapula, by which the glenoid or articular portion of the bone, together with the coracoid process, becomes detached from the rest of the scapula ; the head of the humerus falls into the axilla, with the glenoid cavity attached to it by means of the capsular ligament. Sir Astley Cooper says the diagnostic marks of this injury are three : first, the facility with which the parts are replaced ; secondly, the immediate fall of the head of the bone into the axilla when the extension is removed ; and thirdly, the crepitus which is felt at the extremity of the coracoid process when the arm is rotated. The best method for dis- covering the crepitus is as follows ; let the surgeon's hand be placed over the top of the shoulder, and the point of his forefinger be rested on the coracoid process ; the arm being then rotated, the crepitus is distinctly per- ceived, because the coracoid process being attached to the glenoid cavity, and being broken off with it, although itself uninjured, crepitus is communicated through the medium of that process. We believe this accident to be exceedingly rare. D. Fracture of the superior extremity of the humerus. — The superior extremity of the humerus may be broken across, in the line of its anatomical neck, or through the head of the bone above this oblique line. In both cases the fracture will be intra-capsular. Secondly, the fracture may be extra-cap- sular, passing through the tubercles ; beneath the anatomical neck of the humerus, yet above the line of the junction of the epiphysis, with the shaft of the bone. Thirdly, a fracture may traverse the hu- merus in the line of junction of the epi- physis with the shaft of this bone, or close to this line.* Fourthly, the humerus may be fractured in the part called the surgical neck, beneath the hue of junction of the epiphysis with the shaft. 1. Intracapsular fracture of the humerus. — We find on record fractures of the head of the humerus, which were altogether intra- * Dr. R. Smith has exposed well the error of con- founding together as the same the line of the ana- tomical neck of the hmnenis, and the line by which the superior epiphysis is united -with the shaft of the bone. articular ; and in these cases the head of the bone was separated at the proper anatomical neck. Boyer states he has met with many such cases, most of which were fatal I'rom the severity of the injuries which accompanied the fracture. He mentions the case of a woman who lived for seven days, after having received one of these severe injuries. On making a post-mortem examination of the shoulder, the separated head of the humerus had suffered a great loss of substance; it was hollowed out as to its fractured surface, so as to represent a complete hollow cap or " ca- lotte." It seems to be the opinion of many, that in cases of intra-capsular fractures of the superior extremity of the humerus, unless some portions of synovial membrane and periosteum remain unbroken, no bony consoli- dation can occur. This may be true as to some fractures ; but, on the other hand, we have evidence of cases in which the head of the humerus must have been completely broken, as well as all its membranous cover- ings severed ; and yet perfect reunion of the portion of bone which had been detached was established ; but in these cases it is to be observed, that impaction, to a certain degree, of the head of the humerus into the shaft, had occurred. The possibility of the consolidation, by bony union, of a fracture of the anatomical neck of the humerus had been long doubted. Upon this subject, J. Cloquet observes : " I have, some years ago, made known a case of fracture of the humerus through its anatomi- cal neck, which had been perfectly united. Reichel had before published a similar fact: sometimes the consolidation in these cases would appear to be accomplished by the agency of the inferior fragment, from which spring up stalactiform productions, which surround and encase the superior fragment." He adds, *' we have also met with examples, in which consolidation did not take place. In these last cases, the head of the bone has been found to have been hollowed out, by contact with the inferior fragment, so that a false joint had been formed in the situation of the fracture ; and the superior fragment, by its inferior surface, represented a hollow cup, or ' calotte articulaire.'"* The following cases will show that a frac- ture through the anatomical neck of the hu- merus may occur, in which the head of the bone may be subsequently impacted into the shaft, and be then consolidated by bony union. A female, aet. 47, was admitted into the Richmond Hospital, under the care of the late Dr. Macdovvell, for an injury of the hu- merus, the result of a fall upon the shoulder. The case has been merely entered in the Hospital Case-Book, " a fnicture of the humerus." Five years afterwards, the wo- man was admitted into the same hospital, under the care of Mr. Adams, for another in- jury, a fracture of the thigh, of which she died. Post mortem, the shouKler was care- * Cloquet, Dictionuaire de Medicine, article Frac- ture. 602 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. fully examined. The arm was sliiihtly short- ened. The contour of the shoulder was not as full nor as round as that of its fellow, and the acromion process was more prominent than natural. L^pon opening the capsular ligament, the head of the humerus was found to have been driven into the cancellated tis- sue of the shaft, between the tuberosities, so deeply as to be below the level of the summit of the great tubercle ; this process had been split and disj)laced outwards; it formed an ob- tuse angle with the outer surface of the shaft of the bone. The distance to which the su- perior fragments had penetrated into the shaft is well seen in the wood-cut {Jig. 432.) Fig. 432. Tlie head of the humerus impacted. Nelaton and Smith* have alluded to cases of intra-capsular fractures of the head of the humerus, in which the detached head of the bone became inverted on itself, and was thus impacted into the shaft of the humerus. Nela- ton observes : — "Dr. Dubled showed me a specimen, in which the cap which the sunmiit of the head of the humerus forms had been broken from the shaft, and afterwards in- verted on itself, so that the broken surface of the upper fragments looked upwards and in- wards, while the smooth polished articular part looked downwards, and in this position was buried into the shaft or inferior fragment. Notwithstanding this displacement, consoli- dation had taken place.'' The superior frag- ment was enveloped by stalactiform produc- * Dr. R. Smith's work on Fractures, tions, which had sprung up from the shaft of the humerus. In the year 1843, Dr. Robert Smith laid before a meeting of the Pathological Society of Dublin, a remarkable specimen of a frac- ture of the neck of the humerus, in which the head of this bone was driven into the shaft, splitting asunder the bone in the situation of the tuberosities. The subject of the observa- tion was a woman, aet. 40, who, many years before her death, had met with the accident. On proceeding to make the post-mortem ex- amination of this case, it was remarked that the acromion process was prominent ; the del- toid flattened ; the arm was shortened ; the glenoid cavity could not be felt ; the shaft of the humerus was drawn upwards and inwards, so as to be almost in contact with the cora- coid process ; the motions of the joint were limited ; and the capsular muscles atrophied. Dissectiofi. — When the soft parts were re- moved, and the capsular ligament was opened, the traces of a fracture having long ago passed through the anatomical neck of the humerus were obvious. The head of the humerus was solidly united to the shaft. But, upon ex- amining further, what struck Dr. Smith as very remarkable was, that the head of the humerus was found reversed, or turned up- side down, in the articulation ; or, in other words, the fractured surface was turned up- wards towards the glenoid cavity, and the cartilaginous articulating surface turned down- wards, as in Nehiton's case, towards the shaft. The only explanation of this circumstance which can be given is, that the head of the bone, at the time of the accident, had been completely separated from the shaft by a frac- ture through the anaiomical neck ; that thus rendered free in the interior of the joint, the head of the bone became inverted on itself, and was thus subsequently driven into the cancellated structure, between the tubercles. It appears that in the Museum of the Col- lege of Surgeons of Dublin, a third specimen of this complete inversion of the upper frag- ment of the brok- n humerus is to be found.* 2. Extra-capsular fracture through the tuber- cles.— The fracture may be extra-capsular ; passing through the tuberosities beneath the anatomical neck of the humerus, yet alcove the line of the junction of the epiphysis, with the shaft of the bone. This fracture is usually the consequence of severe falls on the outside of the shoulder; it may occur at all ages, but is most frequently met with in elderly persons. The line of the lesion may be transverse, but usually the bone is broken into many fragments. There is some shortening of the arm, but very little if any transverse displacement of the bony fragments The long tendon of the biceps, in front, and the strong fibres proceeding from the bony attachment of the capsular ligament and capsular muscles, will retain the fragments in their place. The shortening is the result of the mutual impaction into each other of * See Dr, K, Smith's work on Fractm"es. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 603 the superior and inferior fragments. As the fracture thus generally exists without any very obvious displacement of the fragments, and as it is usually accompanied by much swell- ing of the shoulder joint, the diagnosis may be very obscure. Syviptovis. — The patient will complain of severe pain in the shoulder, which is much increased by the least pressure, or by commu- nicating any movement whatever to the arm ; and he cannot, by any voluntary effort of the muscles of the injured arm, elevate it ; on making a methodical examination soon after the accident has occurred, crepitus can be elicited. As to the degree of power which the patient possesses of moving his arm in these cases, some variety may be noticed, par- ticularly if some days have elapsed since the receipt of the injury. The following case of fracture through the tuberosities of the humerus was very recently under observation at the Richmond Hospital, and may be here adduced, to show the diffi- culty that may occur in making our diagnosis if the case is not seen soon after the occur- rence of the accident. Case. — Mary Trainor, aet.CO, was admitted into one of Mr. Peile's wards in the Richmond Hospital on the 19th of May, 1848. She com- plained much of the left shoulder, on which she had fallen fourteen days before. She had never used her arm since the accident, nor left it unsupported. The patient pointed to one part close to the head of the humerus anteriorly, which was particularly painful, and here a small bony projection was detected, whether a spicula of bone or a small exostosis could not be known. She could elevate, or abduct her arm some inches from her side, and could rotate it freely herself, without these movements causing her any pain. Although many examinations had been made since her admission into the hospital, no satisfactory evidence of crepitus could be detected; there was some tumefaction, and heat showing in- flammation of the shoulder joint. She died suddenly of apoplexy on the fourth day after her admission. Post-mortem. — Before the shoulder joint was examined, it was ascertained by careful measurement from the posterior angle of the acromion to the outer condyle of the humerus, as well as from the scapular ex- tremity of the clavicle to the same point below, that the left or injured arm was fully one quarter of an inch shorter than the right. On removing the muscles and their tendons, a fracture was seen to have traversed the superior extremity of the humerus : the line of this fracture was somewhat irregular ; pos- teriorly it passed along the basis of the head of the humerus, or nearly as high as the level of the anatomical neck, and anteriorly along the basis of the lesser tuberosity, which was thus left attached to the head, while the greater tuberosity was detached, and broken into frag- ments ; and it appeared as if this last was the mechanical result of the impaction of the head into the cancelli of the shaft of the bone; the amount of this impaction was to the extent of one quarter of an inch. The synovial mem- brane was perforated or punctured in one or two points by spicula; of the broken humerus, and this membrane showed decided traces of having been the seat of inflammatory action. The cartilaginous coverinjr of the head of the humerus seemed to have been somewhat thinned — the result of the inflammation which had engaged the joint more or less ever since the occurrence of the accitlent. The diagnosis in this case was very diffi- cult, for there was some swelling and decided inflammation of the shoulder joint: fourteen days had passed since the accident occurred, and no crepitus, although carefully sought lor, could at this period be detected. Apparently self-persuaded that no fracture existed, the woman repeatedly showed to Mr. Robert Macdonnell (the resident pupil, who had im- mediate charge of the case) how freely she could rotate the injured humerus ; she could also abduct the elbow some inches from her side. A fracture through the superior part of the humerus was suspected ; but as there was no obvious displacement of the fragments, the principal indication seemed to be to reduce the inflammation of the shoulder joint, and this hne of practice was j)ursued. The ex- pedient of making a comparative measure- ment as to the relative length of the two arms was not thought necessary as an aid in the diagnosis of this case ; yet the result of this experiment would have shown in the living as it did subsequently in the dead body, a decided shortening of the left arm to the amount of a quarter of an inch, an ob- servation which would no doubt have con- firmed the idea already existing in the minds of the attendants, that a fracture of the hu- merus existed, as well as an inflammation of the shoulder joint. 3. Fracture of the superior extremity of the humerus throiigti the line of junction of the cpi" physis with the shaft of the bone, or close to this line. This is a species of fracture which not un- frequently occurs in early life. In the old subject we occasionally witness cases of frac- ture in the same situation. This accident is so far unlike that last adverted to, that while in the former there is no displacement, the latter accident is attended with considerable deformity. We may make this general remark with respect to fractures above the line of junction of the epiphysis, whether the fracture be extra-capsular or intra-capsular. — There is little or no deformity, and crepitus (a symptom of fracture, the possibility of eliciting which usually exists), and shortening to a small amount of the length of the humerus, are the only positive signs to which we can refer to establish our diagnosis ; but when a fracture of the humerus, either at the line of junction of the epiphysis with the shaft of the bone, or beloio this hne in the surgical neck, occurs, then niuch displacement of the frag- ments may generally be observed. Sir A. Cooper has described an assemblage ABNORMAL COXDITIONS OF THE SHOULDER JOINT. of symptoms belonging to a class of cases of fracture of the superior extremity of the hu- merus, which we have no doubt he conjectured to belong to the separation of the superior epiphysis from the shaft of the humerus in the young subject. In the adult, a fracture through the original line of junction of the superior epiphysis with the shaft of the humerus would be attended with nearly similar symptoms. In alluding to the injury in question. Sir A. C. observes, that in children it is the result of falls upon the shoulder. The signs of it are as follow : — The head of the bone remains iu the glenoid cavity of the scapula, so that the shoulder is not sunken as in dislocation; when the shoulder is examined a projection of bone is perceived upon the point of the coracoid process, and when the elbow is raised and brought forward this projection is rendered particularly conspicuous. By drawing down the arm the prominence is removed, but it im- mediately re-appears upon ceasing to make the exten-ion, and the natural contour of the shoulder is lost. All the movements of the shoulder joint are painful, and the patient cannot raise the arm unless b}' the aid of the other hand. The elbow is with difficulty withdrawn from the side, and the arm requires support. Sir A. Cooper adduces a case illustrating the above symptoms in a child £et. 10, who had fallen on the shoulder into a sawpit the depth of which was eight feet. The writer has witnessed many examples of fracture of the humerus in the line of junction of the superior epiphysis with the shaft of the bone, or in the inmiediate vicinity of this line. In these cases the youth of the patient, and the situation of the fracture, led him to con- jecture that a separation ot' the superior epi- physis of the humerus had occurred ; but he had no opportunity of ascertaining anatomi- cally the true nature of the lesion. The principal deformity noticed by the writer in these cases is attempted to be de- lineated in (fg. 433.), the representation of one of the plaster casts which he has preserved of one out of many of these cases. The pro- minence here delineated is found to be owing to a very remarkable projection forwards of the upper extremity of the inferior fragment of the humerus. This was best seen by view- ing the shoulder in profile, or sidewise. The antero-posterior measurement of the shoulder was much increased. Sir A. Cooper, in re- ference to the cases he has seen of this kind, observes, that when the shoulder is examined a projection of bone is perceived "at the front of the coracoid process in four cases which the writer has witnessed, the projection of bone formed by the superior extremity of the lower fragment of the humerus was situated exactly in the centre of a line stretching an- teriorly from the acromio-clavicular articula- tion to the lower margin of the anterior fold of the axilla. This remarkable projection of the bone, formed by the lower fragment, was in two cases engageil in the deeper lasers of the integuments covering the deltoid muscle near to its anterior margin, and hence the deltoid muscle must have been itself per- forated. In these latter cases it was found impossible to disengage the bone from its faulty position, or from the fibres of the deltoid Fig. 433. Case of C. Austin. Fracture of the humerits in or near the line of Junction of the epiphysis. muscle, and deeper layer of the integuments. The following case of the above description has been recently seen by the writer. Case. — Fracture through the humerus imme- diatehj below the tuberosities^ or through the original line of junction of the epiphysis and shaft of this bone. — Charles Austin, aged 14 years, on the morning of the 12th April, 1S46, fell from a height of seven feet otF a ladder, and was thrown on the posterior part of his left shoulder on uneven ground. He was not seen until next morning, when the injured shoulder presented the following appearances * ; — ** There was a great deal of ecchymosis and swelling about the joint : the acromion process appeared pro- minent, and in viewing the shoulder sidewise the measurement of its antero-posterior diame- ter appeared greatly increased. The patient supported the hand and fore-arm of the injured arm with the opposite hand ; the elbow was slightly abtiucted, but it could be readily pressed against the side. He couhl not him- self make the least effort to move the arm, and the attempt to raise it from the side, or to deprive it, even for a moment, of the sup- port of the right hand, was productive of much pain. On placing one hand over the joint, and rotating the humerus with the other, * For the notes of this case, the writer is obliged to ^Ir. W. Court, resident surgeon to Steeven's Hos- pital, with whom he examined it. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 605 a distinct crepitus could be perceived. The head of the bone could be felt in the glenoid cavity, and when the shaft of the humerus was rotated no motion was communicated to the head. On the seventh day after the accident all swelling had subsided, and the appearances noted were as follows : — On viewing the shoulder in front, a very remarkable angular projection of bone forwards is observed. This prominence is very near the anterior margin of the deltoid muscle, and near the centre of a line drawn from the scapular end of the clavicle to the margin of the anterior wall of the axilla. This projection is evidently the abrupt termination of the upper extremity of the lower fragment of the humerus ; every movement communicated to the shaft of the bone also moves this projecting point, a little below, and to the outside of which, an indent- ation or slight puckering of the skin is observ- able. This last we can readily suppose has been produced by the lower fragment having perforated the deltoid muscle, and engaged itself in the deeper layer of the integument. " On viewing the joint sidewise or in pro- file, the posterior angle of the acromion pro- jects much behind, while the abrupt promi- nence already mentioned, formed by the shaft of the humerus, is very salient in front; so that in this side view, the antero-posterior diameter of the joint is seen to be much in- creased. The long axis of the arm is di- rected from above downwards and backwards, very slightly also outwards. By measurement from the acromion to the external condyle of the humerus, the injured side is found to be a quarter of an inch shorter than the oppo- site. The patient cannot himself perform any of the movements of the shoulder joint, ex- cept that of rotation to a small extent, but can permit the humerus to be freely moved by another. Although crepitus was evident at first, now, seven days having elapsed since the accident, it can no longer be elicited. May Yith. — Nearly a month has passed since he received the fall ; he has regained considerable power of motion over the left arm, can even raise his hand to the top of his head. On the Cth of June he left the hospi- tal, being able to use his arm ; the deformity, consisting in the abrupt projection of bone, was somewhat reduced." 4. Fracture of the surgical necJc of the hu- merus below the tuberosities and original line of junction of the epiphysis with the shaft of the lone. — In this case there is much de- formity to be observed. The head and tuber- osities form the superior fragment, which in general remains in its natural situation, while the upper extremity of the lower fragment, which last is constituted b}^ the principal part of the shaft of the humerus, is drawn upw^ards and forwards under the pectoral muscle. When the arm is grasped at the elbow by the surgeon, and pushed upwards, the upper ex- tremity of the broken shaft of the humerus is made to project at the inner side of the coracoid [)rocess of the scapula, and is felt to roll whenever the arm is rotated. Fracture of the humerus in its surgical neck occurs at different heights in this bone. The most common situation for the fracture is where the spongy portion of the bone unites with the rest of the shaft ; and here it is that the humerus, considered anatomically, would seem to be tlie least capable of resist- ing external violence. The direction of the fracture is generally transverse, more rarely is it oblique, and, in this last case, the ob- liquity is generally in a line from without in- wards, and from above downwards, parallel to the line of the anatomical neck of the hu- merus, but below it, and the nature of the displacement is variable. Most frequentlv the inferior fragment is drawn inwards towards the axilla; but the inferior fragment has been also observed to be displaced and become prominent in other directions. Desault has seen it thrown backwards ; Dupuytren, Pa- letta, Duret, and others, have seen it raised up, and even perforate the deltoid muscle outwards ; finally, it more frequently still has been observed to become prominent in front towards the coracoid process. Mons. Gely has, in the Journal de Chi- rurgie, mentioned a case of fracture of the surgical neck of the humerus, in which the fracture was oblique, the obliquity running parallel with, but below, the anatomical neck of the humerus. The inferior fragment had perforated in front the deltoid muscle, very near to the interstice which separates the deltoid from the pectoral muscle ; the arm was shortened an inch. These observations refer to the altered position of the inferior fragment, resulting from a fracture through the part of the humerus called the surgical neck. It is said that usually the superior fragment remains in its normal position in these fractures, but this is not always the case. Malgaigne narrates a case of a man, aged 78, in whom the humerus was fractured transversely in its surgical neck, about an inch and a half above the folds of the axilla. There was an overlapping of the bones; the in- jured arm was consequently one inch and a half shorter than the other. The fracture during life could not be reduced ; he died on the twenty-sixth day after the injury. The inferior fragment was drawn inwards and for- wards, and indeed during life had raised up the soft parts towards the union of the del- toid and pectoral muscles, more internally than the situation of the coracoid process; the over- lapping of the fragments was to the amount already mentioned. The fracture through the humerus was beneath the tuberosities, the longitudinal axis of the lower fragment was in the direction upwards and inwards, and the longitudinal axis of the upper fragment was directed downwards and outwards. In a word, the superior fragment was in a pos'- tion which would correspond to the highest elevation of the arm in the normal state ; and the inferior, on the contrary, was in a position which corresponded to its greatest depres- sion. Dislocations.— The head of the humerus 606 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. may be dislocated from the glenoid cavity of the scapula as the result of accident, in three different directions ; namely, downwards and inwards, into the axilla. Secondly, forwards and inwards. Thirdly, backwards on the infra-spinatus fossa, or on the dorsum of the scapula. Partial dislocations, or subluxations of the head of the humerus, as the result of acci- dent, have been much spoken of, and accounts of such supposed accidents are to be found in the works of practical surgeons. While we would not deny that cases deserving the name of partial luxations of the head of the humerus do occasionally present themselves to the surgeon, in our experience all such cases have been found, on strict inquiry, not to have been the direct effect of accident, but the result of chronic disease, or of congenital malformation of the shoulder joint. And we here formally deny that the case of partial luxation of the head of the humerus, as the result of accident, has ever been satisfactorily proved, either in the living or the dead sub- ject. I. — Dislocation downwards and inwards into the axilla. — The dislocation of the hu- merus downwards is unquestionably the most common, and is generally produced by a fall on the elbow, or palm of the hand, the arm being at the time extended from the body. The humerus, therefore, immediately prior to the accident, would be so related to the glenoid cavity as to form with it an acute angle inverted ; and the head of the bone, thus gliding from above downwards, is forced violently against the lower part of the cap- sule, which is stretched and lacerated so as to allow the head of the humerus to escape ; this result is further aided by the weight of the body, and by the contraction of the great pectoral, latissimus dorsi, and teres major muscles. The new position assumed by the head of the dislocated bone is on the inner side of the anterior margin of the scapula, between the subscapular muscle anteriorly, and the long head of the triceps, posteriorly. The pectoralis major, latissimus dorsi, and teres major muscles act upon the arm as on a lever, of which the elbow is the fulcrum, and the point of resistance is at the articulation ; while the elbow rests on the ground, and the weight of the body presses on the lower part of the capsular ligament of the shoulder joint, the muscular folds of the axilla being in- stinctively thrown into violent action, make an effort to approximate the arm to the side; but as these muscles cannot move the lower extremity of the humerus, on account of the elbow resting on the ground, tlie head of the bone becomes the moving point, and bursts through the lower part of the capsular liga- ment, and is dislocated into the axilla. Dis- location dowmuards may, according to some authors, be produced by a violent blow on the outer part of the shoulder, below the acromion ; but in that case it is often compli- cated with fracture of the scapula or humerus. It is further possible that it may result from simple muscular action, as in the act of lift- ing a heavy weight, or during an attack of epilepsy ; in either case a violent effort is re- quired, whether the effect be attributed to the agency of the deltoid, in depressing the head of the bone, or, as Boyer supposes, to the action of the great pectoral, latissimus dorsi, and teres major muscles, simultaneously co- operating with the elevators of the arm. Si/mptows. — The usual signs of this disloca- tion into the axilla, are the following : — A hol- low is formed below the acromion, in conse- quence of the displacement of the head of the humerus from the glenoid cavity. The deltoid muscle is flattened and dragged down with the depressed head of the bone, so that the na- tural roundness of the region of the shoulder is lost. The arm is somewhat longer, and the anterior fold of the axilla is deeper than na- tural, because the new situation occupied by the head of the bone on the subscapular fossa of the scapula, is below the level of its na- tural position in the glenoid cavity (Jig. 434.). The elbow is with difficulty made to touch the patient's side; this movement is the source of much pain, as it causes the head of the dislocated bone to compress the nerves in the axilla; and upon this account the patient himself supports his arm at the wrist with the other hand. The head of the OS humeri can be felt in the axilla, but not except the elbow be considerably removed from the side. *' I have," says Sir Astley Cooper, " several times seen surgeons de- ceived in these accidents, by thrusting the fingers into the axilla, when the arm is close to the side, when they have directly said, ' This is not a dislocation ; ' but upon raising the elbow from the side, the head of the bone could be distinctly felt ; for that movement throws the head of the bone downwards, and more into the axilla." The surgeon finds some difficulty in overcoming the fixedness of posi- tion of the humerus in its new situation. The patient's voluntary power of abduction of the arm, and of rotation, are lost ; the motion of the limb forwards and backwards is preserved. There is great difference in respect to the movements which can be conmiunicated to the limb, depending on the tone of the mus- cles ; because, if the muscles are relaxed and feeble, from age or any other cause, the sur- geon may be able to move the patient's arm freely, and to raise it up to the head, and even press the elbow close to the side. On moving the limb, a slight cre[)itus will sometimes be felt, but by a continuance of the motion, this soon ceases ; the crepitus, however, in these cases is never like the rough grating which is felt when a fracture is examined. The direc- tion of the longitudinal axis of the arm is changed; for the lower extremity of the hu- merus being placed outwards from the side, its longitudinal axis, if prolonged upwards, instead of passing towards the glenoid cavity, may be observed to be directed inwards to- wards the axilla. In this accident, numbness of the fingers is sometimes complained of, arising from the pressure of the head of the ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 607 bone upon some of the nerves of the brachial plexus. Anatomical characters of the dislocation into the axilla. — Sir Astley Cooper informs us that he dissected two recent cases of this dis- location : — "First case : A sailor fell from the yard-arm on the ship's deck, injured his skull, and dislocated the arm into the axilla. He was brought into St. Thomas's Hospital in a dying state, and expired iiiunediately after. On the next day the shoulder joint was mi- nutely examined, and the following were the appearances found : — On removing the integu- ments, a quantity of extravasated blood pre- sented itself in the cellular membrane, lying immediately under the skin, and in that which covers the axillary plexus of nerves, as well as in the interstices of the muscles, extending as far as the cervix of the humerus, below the insertion of the subscapularis muscle. The axillary artery and plexus of nerves were thrown out of their course by the dislocated head of the bone, which was pushed back- wards upon the subscapularis muscle. The deltoid muscle was sunken, with the head of the bone. The supra-and infra-spinati were stretched over the.' glenoid cavity and inferior costa of the scapula. The teres major and minor had undergone but little change of po- sition ; but the latter, near its insertion, was surrounded by extravasated blood. The coraco-brachialis was uninjured. In a space between the axillary plexus and coraco-bra- chialis, the dislocated head of the bone, co- vered by its smooth articular cartilage and by a thin layer of cellular membrane, appeared. The capsular ligament was torn on the whole length of the inner side of the glenoid cavity, and would have admitted a much larger body than the head of the os humeri through the opening. The tendon of the subscapularis muscle which covers the ligament, was also extensively torn. The opening of the liga- ment, through which the tendon of the long head of the biceps passed, was rendered larger by laceration, but the tendon itself was not torn. The head of the os humeri was thrown on the inferior costa of the scapula, between it and the ribs, and the axis of its new situ- ation was about an inch and a half beloiv the centre of the glenoid cavity from which it had been thrown. T'he second case" adds Sir Astley Cooper, " which I had an opportunity of examining, was one in which the disloca- tion had existed five weeks, and in which very violent attempts had been made to reduce the dislocated bone, but without success. The sub- ject of the accident was a woman, fifty years of age. All the appearances were distinctly marked ; the deltoid muscle being flattened, and the acromion pointed ; the head of the bone could also be distinctly felt in the axilla. The skin had been abraded during the at- tempts at reduction, and the woman apparently died from the violence used in the extension. Upon exposing the muscles, the pectoralis major was found to have been slightly lacer- ated, and blood was effused amongst its fibres; the latissimus dorsi and teres major were not injured ; the supra-spinatus was lacerated in several places ; the infra-spinatus and teres minor were torn, but not to the same extent as the former muscle ; some of the fibres of the deltoid muscle, and a few of those of the coraco-brachialis, had been torn, but none of the muscles had suffered so much injury as the suj)ra-sj)inatus. The biceps was not in- jured. Having ascertained the injury which the muscles had sustained in the extension, and, in some degree, the resistance which they opposed to it, I proceeded to examine the joint. The capsular ligament had given way in the axilla, between the teres minor and sub- scapularis muscles ; the tendon of the sub- scapularis was torn through at its insertion into the lesser tubercle of the os humeri, and the head of the bone rested upon the axillary plexus of nerves and the artery. Having de- termined these points by dissection, I next," says Sir Astley Cooper, " endeavoured to re- duce the bone, but finding the resistance too great to be overcome by my own efforts, I became very anxious to ascertain its origin. I therefore divided one muscle after another, cutting through the coraco-brachialis, teres major and minor, and infra-spinatus muscles. Yet still the opposition to my efforts re- mained, and with but little apparent change. I then conceived that the deltoid must be the chief cause of my failure, and, by elevating the arm, I relaxed this muscle ; but still could not reduce the dislocation. I next divided the deltoid muscle, and then found the supra- spinatiis muscle my great opponent, uritil 1 drew the arm directly upwards, when the head of the bone glided into the glenoid cavity. The deltoid and supra-sjnnatus muscles are those which most powerfully resist reduc- tion in this accident." This dissection ex- plains the reason why the arm is sometimes easily reduced, soon after the dislocation, by raising it suddenly above the horizontal line, and placing the fingers under the head of the bone, so as to lift it towards the glenoid cavity, which will sometimes prove effectual, because, in this position, the muscles are relaxed, so as no longer to offer any resistance to reduction. Sir Philip Crampton has adduced an example of dislocation of the shoulder joint, which illustrates in a satisfoctory manner the anatomy of a recent case of dislocation into the axilla. Case. — " In the year 1808, a labouring man was brought into the County of Dublin In- firmary in a dying state : the persons who carried him stated that he had been engaged in digging under the foundation of a house that had been burned ; that a part of a par- tition wall fell upon him, and that they had found him buried under the rubbish : the man did not survive more than two hours. On examining the body eighteen hours after death, it was observed, that in addition to the injury of the head, which had proved fatal, the right humerus was dislocated into the axilla. To this part I directed the whole of my attention. I made a careful dissection of the joint, pre- viously to reducing the dislocation, and was so fortunate as to obtain a drawing of the 608 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. parts, executed upon the spot, by a distin- guished artist. On removing the integuments of the axilla, the cellular membrane, which was extensively ecchymosed, formed a kind of cap, closely embracing the head of the os humeri, which, when the axilla was cleared, was seen lodged on the inferior costa of the scapula, or rather, on its neck ; the head of the bone, in escaping from its socket, had pushed the teres minor downwards, and burst through the lower part of the subscapularis muscle, some of the fibres of which closely embraced the neck of the bone, while the bulk of the us- cle was piixhed upivards, and detached from the inner surface of the scapula (Jig. 4.34.). F^g, 4.34. Aonltary dislocation ; recent case. (After Sir P. Crampton.) The neck of the humerus, therefore, was in some degree embraced by the divided fibres of the subscapularis muscle, while a portion of its head rested on the neck and part of the venter of the scapula, without the interven- tion of any muscular substance. The short head of the biceps, and the coraco-brachialis, were forced to describe a curve outwards, over the neck of the humerus on the sternal side, while the long head of the triceps crossed the neck of the bone obliquely on the dorsal side ; this strangulation of the head of the bone, by the surrounding muscles, was made most apparent when extension was applied to the fore-arm. The biceps and triceps seemed then to close behind tlie head of the bone, and interpose themselves between it and the glenoid cavity ; the tendon of the long head of the biceps remained in its groove, but the sheath in which it runs was partially ripped up. The capsular ligament was com- pletely torn from the lower part of the neck of the humerus, to the extent of more than half its circumference, the torn edge appear- ing like a crest over the head of the bone. The great nerves and blood vessels of the arm were forced to describe a curve backwards, by the pressure of the head of the bone, which was in contact with them. But the greatest injury had been sustained by the articular muscles,' as they have been called, which lie on the back of the scapula. The tendons of the supra-spinatus, the infra-spinatus, and the teres minor, were completely torn off from the humerus, carrying with them, however, a scale of bone, which was ascertained to be the surface of the greater tubercle into which they are inserted." In order to ascertain the nature of the ob- stacles which oppose the reduction of the dislocated humerus, the scapula was fixed, and the arm being raised to nearly a right angle with the body, extension was slowly ap- plied to the arm by pulling at the wrist ; it then appeared that so long as the hand was held supine, the head of the bone remained immovable; the chief resistance appearing to be caused by the closing of the biceps and triceps behind the head of the bone. The muscles of the back of the scapula being de- tached from the greater tubercle, could of course afford no resistance; but, on turning the hand into the prone position, and giving a motion of rotation inwards to the whole limb, the extension being still maintained, the head of the bone glided easily into its socket. The appearances observed in this case are nearly identical with those which are described by Mr. Henry Thompson, in the Medical Ob- servations and Inquiries, while they differ materially from those which were found by Sir Astley Cooper ; establishing an important fact, which, indeed, might have been inferred a priori, that in apparen'h similar dislocations of the humerus, there may be very different ki7ids as well as degrees of lesion, and conse- quently very different causes of resistance to reduction. " In Mr. Thompson's case," Sir P. Crampton adds, " as in mine, the head of the bone was found lodged on the inside of the neck of the scapula, between the subscapu- laris and teres major muscles ; but during the eighteen days which had elapsed since the injury had been received, the ceUidar substance of the axilla had formed a kind of capsular ligament, which embraced the head of the bone, and contained a small quantity of mucus resembling synovia. In ]NIr. Tnompson's case, the capsular ligamient was corajdetely torn from the whole circumference of the humerus. In mine it was detached to the extent of more than half the circumference. In both cases, the attachments of the ten- dons of the supra- and infra-spinatus muscles were torn off with the part of the bone they were inserted into ; in both cases, some fibres of the subscapularis muscle embraced the neck of the bone." In Sir A>tley Cooper's cases, on the contrary, although the tendon of the subscapularis was torn through, the su;)ra- and infra-spinatus muscles retained the connection with the greater tubercle, and " until this muscle icas relaxed, raising the arm, the humerus could not be reduced hy any efforts ichich he (Sir Astley) could make." In cases of dislocation of the humerus into the axilla, which have been left long unreduced, ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 609 the head of the bone is found altered in its the longitudinal axis of the limb passing from form, the surface towards the scapula being below upwards, is much altered, being thrown flattened, a complete capsular ligament en- ^ Fig. ^6, Fia. 435. Axillary dislocation ; case of long standing. virons the head of the os humeri. The glenoid cavity is filled entirely by ligamentary matter, in which are to be found small portions of bone. These must be of new formation, as no portion of the scapula or humerus is broken. A new cavity is formed for the head of the OS humeri on the inferior costa of the scapula, but this is shallow, hke that from which the os humeri had escaped. 2. Dislocation forwards. — This species of dislocation is much more distinctly marked than the former. The acromion is more pointed, and the hollow below it, from the depression of the deltoid, is more considerable. The head of the os humeri can be felt through the skin and pectoral muscle, and its con- vexity seen, in thin persons, just below the clavicle ; and when the arm is rotated, the protuberance may be observed also to rotate and accompany the motions of the arm. The coracoid process of the scapula is placed above and on the outside of the head of the bone, which we know is covered by the pectoris major muscle. The elbow is thrown out more from the side, and further back than it is in the case of dislocation into the axilla ( Jig. 436.). Much difference of opinion seems to pre- vail as to whether the arm is lengthened or shortened, as the result of this dislocation of the head of the humerus forwards. Mal- gaigne and Dupuytren both assert that the arm on the dislocated side is longer than na- tural ; Sir A. Cooper expresses himst If in opposite terms ; he says, that in the disloca- tion forwards and inwards of the head of the humerus, the arm is shortened. In our experience we have never found in the living subject the arm shortened ; and in the speci- men from which ^g. 436. has been taken, the centre of the new glenoid cavity is several lines below the centre of the original cavity, and the arm therefore must have been by, so much, longer than natural. The direction of VOL. IV. Dislocation of the head of the humerus forwards and inwards. inwards towards the middle of the clavicle The pain attending this accident is less than it is in the case where the head of the bone is thrown into the axilla, because the nerves of the axillary plexus are less compressed ; but the motions of the joint are much more materially affected. The strongest diagnostic marks of the dislocation are these. The elbow is separated from the side and thrown backwards, and the head of the humerus can be felt to move below the clavicle when the arm is rotated. Sir Pt^ilip Crampton has adduced the following example of the ordinary dislocation forwards, in which the head of the bone was thrown at once on the neck of the scapula, without previously passing into the axilla. " James Wilson, aet. 30, fell into a lime- kiln, in the innnediate neighbourhood of the Meath Hospital, while the lime was still burning ; he was dmwn up by ropes, but just as he reached the top of the shaft, the rope broke, and he aiiain fell to the bottom, a dis- tance of about fiiteen feet, on the ignited stones. It appeared, on examination, made in the Mea h Hospital, that in addition to several extensive burns and lacerations, there was a dislocation of the humerus, under the pectoral mus- cle. Mr. Macnamara, without assistance, re- duced the di>location, by merely drawing the arm gently forwards and downwards with one hand, while he pushed the head of the bone towards the glenoid cavity with the other. The man died in the course of the day, from the conjoint effects of the burn and the fall. Eighteen hours after death the 610 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. shoulder joint was dissected by Mr. Macna- mara, from whom I take the description of the appearances, with the advantage of having the preparation before me while I write. The dislocation was unattended with rup- ture of any muscle, or the separation of any tendon from its insertion into the bone ; by a slight effort the dislocation was reproduced, and the pectoral muscles being removed, the polished head of the bone was now seen lodged on the cervix of the scapula, at the root of the coracoid process, but extend- ing nearly as far as the notch in the superior margin of the scapula. The head of the bone had passed out through a rent in the capsu- lar ligament, over the upper edge of the tendon of the subscapularis, detaching this muscle from its connection, which is at this point but slight, with the inner surface of the scapula, and pushing its fibres doiunwards, so that they formed a curve, which partly embraced the neck of the humerus {fig. 437.). The supra- and infra-spinatus nnis- cles were on the stretch, but had suffered no injury. The cellular substance cover- ing their tendons was deeply ecchymosed, so as to mark their course most distinctly. On replacing the head of the bone, the open- ing in the capsular ligament through which it Fig. 437. Dislocation forwai'ds and inwards. {Sir P. Cramp- tons case.^ had escaped from its socket, could be dis- tinctly seen. It was formed, by a separation of the ligament from the interior side of the brim of the glenoid cavity from top to bottom, it was bounded at the top by the tendon of the supra-spinatus, and at the bottom by the inferior edge of the tendon of the subscapu- laris ; the rent was continued as far as the root of the lesser tubercle of the os hmneri, and was of sufficient extent, but no more, to per- mit the head of the bone to pass easily through it. The inferior part of the capsular liga- ment, however, the part corresponding to the axilla, was perfect. The great blood vessels and nerves lay to the sternal side of the head of the humerus, and were forced a little out of their course. The axis of the head of the bone in its disturbed position was scarcely a quarter of an inch higher than the axis of the glenoid cavity. Sir P. Crampton observes, " the anatomy of the recent case of dislocation forivards set- tles the long disputed question as to whether or not the humerus can be dislocated primi- tively in any other direction than doivnivards, or into the axilla ; it is plain, that in the case of Wilson, the head of the bone was thrown at once forwards, into the situation into which it appears under the clavicle ; as the inferior portion of the capsular ligament was not ruptured, and the attachment of the sub- scapularis and teres minor muscles to the in- ferior costa of the scapula remained undis- turbed." Mr. Key has given the following account of the appearances observed in dissection of the right shoulder joint of a patient who had had for seven years an unreduced dislocation of the head of the humerus, in the direction for- wards and inwards. The specimen is pre- served in the museum attached to St. Thomas's Hospital. The head of the bone was thrown on the neck and part of the venter of the scapulee, near the edge of the glenoid cavity, and immediately under the notch of the su- perior costa : nothing intervened between the head of the humerus and the scapula, the subscapularis muscle being partly raised from its attachment to the venter. The head was situated on the inner side of the coracoid process, and immediately under the edge of the clavicle, without having the slightest con- nection with the rib^!; indeed, this must have been prevented by the situation of the sub- scapularis and serratus magnus muscles be- tween the thorax and humerus. The tendons of all the muscles attached to the tubercles of the humerus were perfect, and are shown in the specimen preserved. The tendon of the biceps was not torn, and it adhered to the capsular ligament. The glenoid cavity was completely filled up by ligamentous structure, still however preserving its general form and character ; the tendons of the supra- and infra- spinati and teres minor muscles adhered by means of bands to the ligamentous structure occupying the glenoid cavity, and, to prevent the effects of friction between the tendons and the glenoid cavity in the motions of the arm, a sesamoid bone had been formed in the substance of the tendons ; the newly formed socket reached from the edge of the glenoid cavity to about one-third across the venter; a complete lip was formed around the new cavity, and the surface was irregularly co- vered with cartilage. The head of the bone had undergone considerable change of form, the cartilages being in many places absorbed, and a complete new capsular ligament had been formed." The accompanying wood-cut (fig. 438.) is taken from a scapula preserved in the museum of the College of Surgeons in Dublin, and re- ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 611 sembles much the specimen alluded to by Mr. Key. The newly formed socket reached from Fig. 438. Dishcation forwards and downwards. ( Original, from tlie museum of the College of Surgeons, Dublin.) the edge of the glenoid cavity, to about one- third across the subscapular fossa ; a deep cup was formed lor the reception of the dislocated head of the humerus; the inner margin of this cup was fully half an inch above the level of the subscapular fossa; the glenoid cavity had lost all cartilaginous investment ; it was rough on its surface from bony deposition, and its inner margin was elevated somewhat into a sharp ridge, so as to form part of the margin of the new articular cavity for the head of the humerus. 3. Dislocation backwards of the head of the humerus on the dorsum of the scapula^ the result of accident. — In this dislocation the arm is Fig. 439. Dislocation on the dorsum of the scapida. directed from above downwards, inwards, and forwards. The deformity of the joint is well seen by viewing it in front, where a deficiency is noted of the normal roundness of the articu- lation. When w^e look at the shoulder side- ways, the head of the humerus may be seen to form a remarkahle saliency behind the posterior angle of the acromion. In this dislocation the head of the bone is thrown on the posterior surface of the scapula inmiediately below the spine of this bone, and there forms a very re- markable protuberance, and when the elbow is rotated as far as practicable this protuberance moves also. The dislocated head of the bone may be easily grasped between the fingers, and distinctly felt resting below the spine of the scapula; the motions of the arm are impaired, but not to the same extent as in the other luxations of the shoulder, and the longitudinal axis of the humerus may be observed to run upwards, backwards, and to a point, evidently behind the situation of the glenoid cavity. In Guy's Hospital Reports* Sir A. Cooper has published a case of this species of dislocation, from which we abstract the following. Case. — " Mr. Key has given me the par- ticulars of the following case. Mr. Comphn was 52 years of age, and had been the sub- ject of epileptic fits ; one of them, which was particularly severe, occurred one morning while he was in bed, and in his violent con- vulsive strugglings his shoulder became dis- located on the dorsum of the scapula, present- ing the ordinary symptoms of this accident in which dislocation had never been reduced." The circumstance most peculiar in this case was, that the head of the bone could by ex- tension be drawn into its natural situation in the glenoid cavity ; but so soon as the force ceased to be applied it slipped back again in the dorsum of the scapula, and all the appear- ances of dislocation were renewed. The se- cond peculiarity consisted in a sensation of crepitus as the bone escaped from its socket, so as to lead to a belief that the edge of the glenoid cavity had been broken off. The patient was unable to use or even to move the arm to any extent, nor could he by his own efforts elevate it from his side, and although he lived seven years after the occurrence of the epileptic fit, he never recovered the use of the limb, Mr. Key sent the following note of the dissection of the dislocated shoulder in this case to Sir A. Cooper : — " The dislocation of Mr. Complin's shoulder arose from muscu- lar action alone in a paroxysm of epilepsy, and during his life it was thought probable that a portion of the glenoid cavity had been broken off, or a piece of the head of the os humeri, or perhaps the smaller tubercle, and that either of these injuries would account for the head of the bone not remaining in its na- tural cavity when reduced. But the inspec- tion, post-mortevi, proved that the cause of this symptom was the laceration of the tendon of the subscapulam muscle, which was found to iadhere to the edge of the glenoid cavity, and was much thickened and altered in its cha- racter from its laceration, and from its very * Astley Cooper on Dislocations, &c., page 384., edition 1842, by Mr. B. Cooper. E R 2 612 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. imperfect and irregular union. The muscles of the dorsum scapulae were diminished, by being thrown out of use, and the tendon of the long head of the biceps muscle was entire, but glued down by adhesion." Upon further ex- amination of the scapula and os humeri, Sir A. Cooper found the muscles and the situation of the bones to be as follows: — *' The head of the OS humeri was placed behind the glenoid cavity of the scapula, and rested upon the posterior edge of that articular surface, and upon the inferior costa of the scapula, where it joins the articulation. When the scapula was viewed anteriorly, the head of the os hu- meri was placed in a line behind the acromion biit below it, and a wide space intervened be- tween the dislocated head of the bone and the coracoid process, in which the fingers sunk deeply towards the glenoid cavity of the sca- pula. When viewed posteriorly, the head of the OS humeri was found to occupy the space between the inferior costa and spine of the scapula, which is usually covered by the infra- spinatus and teres minor muscles. The tendon of the subscapularis muscle, and the internal portion of the capsular ligament, had been torn at the insertion of that muscle ; but the greater part of the posterior portion of the capsular ligament remained, and had been thrust back with the head of the bone, the back part of which it enveloped. The supra- spinatus muscle was put upon the stretch, the subscapularis was diminished by want of ac- tion, and the infra-spinatus,^and teres minor muscles were shortened and relaxed, as the liead of the bone carried their insertions back- wards. The tendon of the long head of the biceps muscle was carried back with the head of the bone, and elongated ; but it was not torn. As to the changes in the bones, the head of the os humeri, and the outer edge of the glenoid cavity of the scapula, were in di- rect contact, the one bone rubbing upon the other when the head of the os humeri was moved ; and this accounted for the sensation of crepitus at the early period of the disloca- tion, as there was no fracture. The glenoid cavity was slightly absorbed at its posterior edge, so as to form a cup, in w hich the head of the bone was received, and this latter bone and the articular cartilage had been in some degree absorbed where it was in direct contact with the scapula, as well as changed by attrition during the seven years the patient lived." The surface of the original glenoid cavity, instead of being smooth and cartilaginous, was rough and irre- gular, having elevations at some parts, and depressions at others. The extremity of tiie acromion was sawn off, to look for any little f ragment of bone which might have been broken off, but not the smallest fracture could be per- ceived. ^ Mr. Key, in his account of another case of dislocation of the os humeri backward on the dorsum of the scapula, writes as follows : — " I found a very stout man sitting up in bed in great pain, and complaining more than patients commonly do under dislocation, and 1 concluded it to be some fracture about the cervix, especially as at first view nothing could be seen of a hollow under the deltoid muscle, the joint appearing round as usual. On pass- ing to the man's side to examine the limb, the deformity of the shoulder became visible, the fore[)art appeared flattened, and the back of the joint fuller than natural : the head of the bone could be seen as well as felt, resting on the posterior part of the cervix scapulae. The elbow could be brought to the side, or raised on a level, with the acromion. Rotation out- wards was entirely impeded, in consequence of the subscapularis being stretched, all motions of the liaib giving hira extreme pain, which was referred to the lower part of the deltoid muscle, in the direction of the articular nerves, which were probably injured by the pressure of the head of the bone." The dislocation of the head of the hu- merus backwards on the dorsum of the scapula is said to be very easily recognised, yet the writer has seen two examples of it which had been overlooked at the moment of the accident, and he has heard of two others. When the swelling, the result of the lacera- tion of parts, has subsided, the nature of the injurv becomes very evident indeed. A gentle- man," Mr. A F., aged about So years, called upon the w riter four years ago to examine his shoulder. He stated that he was throw n off a jaunting car about three months previously, and injured his shoulder, and that ever since he had had but very iniperfect use of his arm. The patient had been educated as a medical man, had practised surgery, but did not him- self suspect the nature of" the injury, when, Fig. 440. Case of Mr. A. F.— Dislocation of the head of the humerus backwards on the dorsum of the scapula. about ten weeks after the accident, he called upon the \sriter. Tiie nature of the injury ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 613 was very manifest. The arm was placed close to the side, was neither lengthened nor short- ened; he had no pain in the shoulder joint, but had very imperfect use of the limb. The shoulder had not the flat appearance externally surmounted by the prominent angle formed by the acromion, which characterises the ax- illary dislocation ; nor had he the fulness be- neath the clavicle and in front of the acromion which are noticed in the dislocation forwards ; on the contrary, a deficiency was observed in front beneath the acromion ; and here the fingers could be sunk into a deep fossa, which seemed to extend even to the unoccupied glenoid cavity ; while behind the posterior angle of the acromion a tumor as large as an orange could be seen and felt {fig. 440,). Tliis rounded prominence moved with the shaft of the humerus ; a well-marked vertical groove showed the distinction between the convexity which belonged to the head of the dislocated humerus behind and that which formed the posterior angle of the acromion (/^.440.). An energetic attempt was made at the Richmond Hospital to reduce the dislocation in this case three months after the accident had occurred, but without success. Diagnosis between fractures of the superior extremity of the humerus and dislocations of the shoulder-joint. — As we have already pointed out the symptoms which are peculiar to each of the forms of scapulo-humeral dislocations, we may here direct attention to the fact, that these symptoms are very similar to those which belong to fracture of the upper extre- mity of the humerus : so that in many cases the difficulty of distinguishing between these different injuries is such as to lead not un- commonly to a false diagnosis. Every person labouring under either a fracture or luxation of the superior extremity of the humerus, informs us that he has fallen on that side of the body on which the injury exists ; but the position of the arm at the moment of the accident will be found to have been diflTerent in the case of fracture and dislocation : so that if we know how the limb was placed at the moment of the fall, we may be led to con- jecture from this alone the nature of the ac- cident which has occurred. If, for example, when the patient is falhng, his arm is se- parated from his body directed forwards, or outwards, as it were instinctively to break the fall, and save the upper part of the body, if under these circumstances displacement of the upper part of the humerus occurs, the existing deformity will be found to be the result of dislocation ; but if, on the contrary, the fall takes place when the arm is by the side, as, for instance, in the breeches pocket, and no effort is made by the patient, at the moment of the fall, to raise the arm, the momentum and weight of the body have been received on the point of the shoulder, the resulting injury has been most probably a fracture of the head and upper part of the humerus. In both cases the pain expe- rienced at the shoulder is severe, and gives rise to the impression, on the patient's mind, that he fell on that part ; but if the patient has met with a dislocation, it will be found that in reality he has fallen on the palm of the hand, evidences of which the surgeon will be better able to discover in the ex- coriations which the palm has suffered, than by any report which the patient himself may be enabled to make. When the patient has met with a fracture, we shall, on inquiry, discover that the fall has taken place on the outside of the shoulder ; there is, in this case, no abrasion of the palm of the hand, while con- siderable tumefaction and extensive ecchy- mosis, the effects of contusion, are observ^able along the outer side of the arm. When called to the patient immediately after the accident, we notice those circumstances as to the hand and clothes which will instruct us as to the probability, whether the patient had fallen forwards on the palm of the hand, or com- pletely outwards on the stump of the shoulder. In case of fracture, moreover, there is exten- sive ecchymosis ; in simple dislocation, little, if any; but if it should exist, it is rather on the anterior and internal part of the limb, than on the outside, as in fracture. In both fracture and luxation the acromion is salient, and the deltoid flattened ; but as the dis- placement is more complete in luxation than in fracture, the prominence of the acromion and the depression beneath it are more marked in the former than in the case of fracture. When there is a luxation, and we wish to impart movements to the limb, the humerus often moves in connection with the scapula, as if the two bones made but one body. If there is a fracture, there is abnormal mobility at one point in the upper part of the humerus. This mobility is ordinarily accompanied by a crepitus which is best eli- cited by seiz ng the inferior extremity of the humerus at the elbow and rotating it on its long axis. Finally, great efforts are frequently neces- sary to effect a reduction of the dislocated humerus ; but once replaced, the bone remains in its proper articular cavity, and the de- formity of the shoulder does not recur ; but in fracture, although the bone may be replaced with comparative facility, yet, if it be left un- supported, the deformity will almost imme- diately recur. In the case in which it is not easy to distinguish a fracture from a luxation, Dupuytren gives the precept — " Rendez au membre, par des manoeuvres convenables, sa forme et sa longueur naturelles ; retournez aupres du malade sept ou huit heures apres : si vous trouvez I'epaule deformee, soyez as- sure qiievous avez a faire a une fracture."* Malgaigne has made the observation, that in all luxations of the head of the hu- merus, the head of the bone must descend below its ordinary level, and consequently that, no matter which of the three disloca- tions has occurred, the dislocated arm must be longer than the other. This appears to us * Lemons Orales. R R 3 614 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. to be a point, by attention to which we may be assisted in our endeavours to establish the diagnostic marks between dislocation and fracture, because, in fracture of the humerus, we have ahiiost invariably found, whether from some overlapping of the bones, or im- paction of one of the fragments into the other, that some shortening of the arm exists. If there be dislocation, the arm is sometimes abnormally lengthened, and never shortened. In the measurement of the injured hmb we have therefore a simple means to resort to, which will no doubt assist us much in making our diagnosis. 4. We have heretofore adverted only to the ordinary symptoms and anatomical characters belonging to the three dislocations which the head of the humerus is liable to ; but practical surgeons have, however, noticed that a dis- location of the head of the humerus is some- times combined ivith a fracture of this bone. In this case the fracture 'may sometimes en- gage merely the tuberosities, sometimes the anatomical, and sometimes the surgical neck of this bone. It has been long ago noticed by Thompson *, that when the head of the humerus is dislocated into the axilla, the greater tuberosity of this bone, which gives attachment to the three posterior capsular innscles, is torn off from the shaft of the hu- merus, and left attached to these muscles. This observation of Thompson has since been repeated by others, from amongst whom we have already quoted a case adduced by Sir Phihp Crampton, of an axillary dislocation, in the dissection of which it was found that the tuberosities were detached. Such a com- plication with a dislocation of the humerus would no doubt facilitate the reduction of the dislocated bone, but its subsequent main- tenance in its place would be thereby rendered very difficult. We have reason to believe that a fracture, completely detaching the greater tuberosity of the humerus, may be combined with a dislo- cation forwards ; and in this case, although the dislocation may be reduced, the head of the humerus cannot be maintained in the glenoid cavity. We have for some time con- sidered this to be the explanation of the spe- cimen contained in the Richmond Hospital Museum, an account of which we find given by Dr. R. Smith, and from which we abstract the following: — "Upon removing the soft parts, the head of the bone presented itself, lying partly beneath, and partly internal to the coracoid process. The greater tuberosity, together with a very small portion of the outer part of the head of the bone, had been completely separated from the shaft of the humerus. This portion of the bone occu- pied the glenoid cavity, the head of the hu- merus having been drawn inwards, so as to project upon the inner side of the coracoid process ; it was still contained within the capsular ligament, which was thickened and enlarged, and bone had been deposited in its tissue. A new and shallow socket had been formed upon the costal surface of the neck of the scapula, below the root of the coracoid process, and the inner edge of the glenoid cavity, the tuberosity was united to the shaft only by ligament. The injury had occurred many years before the death of the patient, but the history of the case was not precisely known." But fracture of the greater tuberosity may also occur, as a consequence of falls on the outer side of the shoulder, or otherwise, with- out any dislocation following. Fracture of the lesser tuberosity of the humerus may, we suppose, be an accident likely to attend on dislocations of the head of this bone, and would, we imagine, be at- tended with consequences sim.ilar to those which followed the laceration of the tendon of the subscapularis muscle in a case of dis- location on the dorsum of the scapula, no- ticed by Sir A. Cooper and Mr. Key. Dislocation of the head of the humerus ^ ac- companied with a fracture of the neck of the humerus. — Sometimes the luxation of the humerus is complicated with a fracture of the anatomical or surgical neck of this bone ; we have then one of those rare lesions to deal with, for which nature and art can do but little. In such a case it is plain that the dis- location has first occurred. W^hen there is both a dislocation and fracture, Sir A. Cooper says, the symptoms resemble those which usually accompany the dislocation into the axilla, the head of the bone being there felt ; but there is somewhat less of the hollow to be observed below the acromion, and the del- toid muscle does not seem much depressed, because the broken extremity of the shaft quits the head and lodges in the glenoid cavity of the scapula. Upon rotating the arm, the broken shaft of the bone can be perceived to move under the acromion ; there is but little power of motion ; and considerable pain is felt not only in the shoulder, bat in the arm and hand. The head of the os humeri can be felt when the arm is raised, and the sur- geon's fingers are introduced into the axilla ; but when the arm is rotated at the elbow, the head of the bone remains entirely unmoved, or very little obedient to the motions of the elbow. In some cases, but not always, a dis- tinct crepitus can be perceived. The broken end of the os humeri is drawn somewhat forwards, but is easily pushed into the glenoid cavity, from which, unless it be supported, it is again drawn by the pecto- ralis and coraco-brachialis muscles. The arm, measured from the acromion to the elbow, is shorter than the other.* As this accident is produced by great vio- lence, the parts are nuich obscured by the effusion of blood, and by the inflammation which sj)eedily follows ; but, for the first three hours, the muscles are so lax, that but for the pain it occasions, considerable motions of the limb might be produced. ♦ Medical Obs. and Enq. yol. ii. p. 3-19. * Suiith on Fractiu-es. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 615 In one case detailed by Sir A. Cooper, the tubercles were broken off with the head of the bone, and the fractured extremity of the neck of the os humeri was placed in the glenoid cavity of the scapula. In another case, the fracture was intra-capsular, and the head of the bone was at the same time dis- located forwards, under the pectoral muscle, and placed at the inner side of the coracoid process. Delpech * gives the history of a case of fracture of the anatomical neck of the hu- merus, combined with a dislocation. The case was remarkable, and differed from all the others recorded, in being an example of that rare form of dislocation, where the bone is thrown on the dorsum of the scapula. The history of the case is accompanied with an engraving. With regard to the case of dislocation into the axilla, complicated with fracture. Sir A. Cooper says, " I would observe that in this case the fall and depression of the shoulder is less striking than in the case of simple ax- illary dislocation, as the shaft of the bone fills up the glenoid cavity ; also, that in the case complicated with fracture, the head of the bone can still be distinctly felt in the axilla, and that as it does not move when the os humeri is rotated from the elbow, this be- comes the principal diagnostic mark. " That a grating sensation can generally be felt, and sometimes a very distinct crepitus, especially if the elbow be raised outwards during the rotation of the arm. " That the upper extremity of the shaft of the humerus can be felt advancing to the coracoid process ; but that it is easily re- turned into the glenoid cavity, and that it there rotates with the arm, but easily again slips forward. " That the accident which produces it is much more severe than that by which simple dislocation into the axilla is produced ; and there is, therefore, more contusion, more swelling, and more pain," Muscles. — If in some cases the tuberosities of the humerus are broken off and remain connected with the muscles when the head of the humerus is dislocated, in others, we may be prepared to expect that in the dis- section of cases of dislocation, the capsular and other muscles will be found lacerated. If, as has been stated, the supra-spinatus be the muscle which is most put on the stretch when the head of the humerus is dislocated down- wards, we need not be surprised to learn that this muscle is very frequently found to have been ruptured, or to have torn away a frag- ment of bone from the head of the humerus. In the dislocation on the dorsum of the scapula, the dissection of which is detailed in Sir A. Cooper's work, we find the following observations made by Mr. Key, with reference to a very peculiar phenomenon noticed in that case : namely, " that, during the patient's life-time it was thought probable that a portion * Clinique Chirurgicale, Paris, torn. i. p. 234. of the glenoid cavity had been broken off, or a piece of the head of the os humeri, or perhaps the smaller tubercle ; and that any of these injuries would account for the head of the bone not remaining in its natural cavity when reduced ; but the inspection post- mortem proved that the cause of this symptom was the laceration of the tendon of the sub' scapularis muscle, which was found to adhere to the edge of the glenoid cavity, and much thickened and altered in its character from its laceration, and very imperfect and irregular union." The tendon of the long head of the biceps is sometimes altered, as to its direction, in cases of complete dislocation, and adhesions between it and the contiguous parts occur ; but there are very few cases recorded, or to be found in museums, which prove that in true dislocation from accident, the tendon was found ruptured. In this respect, the effects of accident and disease on this tendon are strongly contrasted ; for, as the result of disease, the tendon, so far as its articular por- tion is concerned, is very generally removed altogether. Besides lesions affecting the bones, mus- cles, and tendons, injuries of other tissues may be found occasionally to accompany or succeed to dislocations of the shoulder. A dislocation of the head of the humerus may be accompanied with an oedematoiis swelling of the arm and forearm ; with a pa- ralysis of the dislocated extremity, or with a laceration of the axillary artery, and a dif- fused aneurism ; it is said also that occasion- ally an emphysematous swelling of the shoul- der has followed the reduction of the dis- location ; and on other occasions, that the articular structures have been attacked with very severe injlammation. For example, as to this last : Mr. Hunter gives an account of a case of dislocation of the shoulder-joint, which he dissected three weeks after its re- duction, from which, if we could be influenced by one case, we might infer that inflammation, though latent, may sometimes be the conse- quence of a dislocation of the head of the humerus. Mr. Hunter's observation is as follows : " What was very remarkable, and what I did not expect, there was a good deal of pus in the Joint.^^ * Partial or general paralysis of the muscles of the arm has also been observed as a con- sequence of a dislocation of the head of the humerus, particularly when either the circum- flex nerve alone, which is that most usually injured, or all the nerves of the brachial plexus have been violently contused, or greatly stretched ; or even torn across either at the time of the accident, or by the violence of the means used to restore the luxated humerus, when the dislocation has been left long un- reduced. Flaubert, of Rouen, speaks of an emphysema of the chest succeeding his efforts to reduce an old luxation of the humerus ; * Pathological Catalogue of Museum of K. C. Surgeons, England, vol, ii. p. 20. No. 868. R R 4 616 ABNORMAL CONDITIOXS OF THE SHOULDER JOINT. and it is known that Desault had already ob- served a similar occurrence. A Memoir, con- taining six cases pubUshed in the Repertoire d' Anatomic et de Chirurgie, by M. Flaubert, surgeon in chief to the Hotel Dieu de Rouen, is not well calculated to encourage practitioners to attempt the reduction of old dislocations. In five of these ras.^s the reduction was fol- lowed by serious accidents. M. Flaubert observes, that in many cases when para- lysis of the upper extremity had been attri- buted to the dislocation itself, he believes it was rather owing to the violent efforts made for its reduction ; laceration of muscles and extensive abrasion of the skin have been no- ticed as the consequence of these efforts, and even death from diffuse inHammation has oc- curred ; but these accidents, whether the re- sult of dislocation, or of the means used to restore the bone to its place, must be consi- dered as rare in this country, as from the comments of Mr. Mar, and the observations of the Editors of the Lecons Orales of Du- puytren, they seem to have been in Paris. The latter observes, " Le hasard qui a fourni a M. Flaubert, dans le court espace de trois ou quatre ans, un ensemble de tous les acci- dens les plus graves qui puissent determiner la reduction, est vraiment extraordinaire : il faut sans doute en chercher la cause dans des circonstances particulieres, qui sont incon- nues."* Alteratiom of the r.erves. — We have noticed as belonging to the symptoms of dislocation of the head of the humerus, that the patient complains of pain extending down the course of the nerves of the arm and the forearm, and also of numbness. These symptoms generally disappear when the dislocation is reduced, but sometimes they persist. The pressure which the nerves of the axillary plexus undergo has naturally been referred to as the cause of these unpleasant svmptoms. The nerves, besides being stretched, have been sometimes even torn across; when this has oc- cured the effects produced must Ions remain ; such cases are very rare. Among all the nerves in the vicinity of the shoulder-joint which have been referred to as the seat of injury the result of luxation of the humerus, the eircum- Jlrx nerve, which supplies the deltoid, is that which has been found most frequently injured. Indeed, from the manner it winds round the neck of the humerus to arrive at its destina- tion at the under surface of the deltoid mus- cle, it can scarcely escape being stretched and elongated, and such a lesion of this nerve we may well expect to be followed by a pa- ralysed condition of the deltoid muscle. The circumflex nerve has been found compressed by the dislocated head of the humerus, flat- tened, and firmly adherent to the capsule of the joint. We find in the Museum of Bartho- lomew's Hospital, (Catalogue, p. 124, vol. i.. No. 42.,) a preparation of a shoulder-joint, exhibiting a dislocation of the humerus, which occurred eighteen months before death. " The * Lemons Orales, vol. iii. page 140. head of the humerus rests on the anterior surface, near the inferior border of the sca- pula. The tendons of all the capsular mus- cles were entire ; the long tendon of the biceps retains its attachment to the glenoid cavity. The cireumjlex nerve is compressed by the head of the dislocated bone, and was in con- sequence flattened, and firmly adherent to the capsule of the joint. The dislocation had been followed by permanent paralysis of the del- toid muscle." Artery. — Luxations of the head of the hu- merus havebeen found complicated with alesion of the axillary artery. This we believe to be a very rare occurrence. M. Flaubert of Rouen cites cases of this lesion to have occurred in the Hotel-Dieu de Rouen, as a consequence of the efforts made by surgery to reduce old luxations of the humerus. In the following case, which the writer thinks of sufficient im- portance to be here introduced, the laceration of the axillary artery was recognised a few minutes after the dislocation had occurred — and before any effort whatever had been made to restore the humerus to its place. Case. — John Smith, eet. 50, was thrown down by a runaway horse one morning during the summer of 1833; in about ten minutes after this occurred, he was brought to Jervis Street Hospital, when the writer, at that time one of the surgeons of the institution, was prescribing for the extern patients. The man was in a cold perspiration, pallid, and apparently on the verge of syncope. The writer imme- diately observed that the patient had a dislo- cation of his left humerus, into the axilla, and, proceeding to point out, as was his cus- tom, to the cluiical class the diagnostic marks of the luxation, he noticed that the cavity of the axilla was filled up to a remarkable de- gree. This sudden filling up of the Hxilla he immediately concluded could be attributed to no other source than to the laceration of a larcje artery. He quickly sought for the pulse in the radial and brachial artery of the dislo- cated limb ; but no pulsation could be felt in any artery below the site of the left subcla- vian, while the pulse, though feeble, could be readily felt at the heart, and in every external artery of the system, except in those of the dislocated arm.* The writer then observed to the clinical class, that in this case there were two lesions to be noticed, namely, a disloca- tion into the axilla, the features of which were very well marked, complicated with a rupture cf the axillary artery ; in a word, be- sides the dislocation there was a diffused aneurism ; the latter was unattended by any pulsat'on, so that he conjectured the artery was completely torn across. He did not long dtliberate as to what course was the best to pursue under existing circumstances, because he felt sure that, so far as the torn artery was concerned, if the head of the humerus was once restored to its place, this vessel would be in at least as favourable a condition * Mr. Brassington, now a practising surgeon at Port Eouines, was one of those present on this oc- casion. ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 617 as it then was, and secondly that the state of prostration and debility (he patient was in, at that moment, offered an opportunity which, if once lost, might not again be afforded, of reducing easily the dislocation. Taking the patient, therefore, unawares, the writer placed his knee in the axilla of the dislocated arm, and then slight extension having been made over this fulcrum, the bone at the first trial returned into the glenoid cavity. The pat ent was placed in bed in the hospital, under the care of the late Mr. Wallace, whose day it was for admitting accidents. There was much more superficial ecchymosis about the axillary, and subclavian region, and along the inside of the left arm, than is usually observed after a simple dislocation of the head of the humerus. The deep axillary swelling re- mained stationary for some days ; but no pul- sation could be discovered either in it, or in the arteries of the limb. A feeble and fre- quent pulse could be felt in the left subcla- vian, and in all the other arteries, as well as in the heart. After the space of ten days, Mr. Wallace's month of attendance having expired, the case came under the care of Mr. O'Reilly, who having been satisfied that a diffused aneurism existed, and was on the increase, performed the operation, at which the writer was present, of tying the subclavian artery in the third stage of its course. The patient recovered, and was discharged from the hospital about two months afterwards ; he lost the last two fingers by gangrene ; but whether from an attack of erysipelas, which succeeded the operation, or from the effects of the ligature of' the main artery of the limb, is not clearly known. The man lived for many years afterwards, in the immediate vici- nity of the Richmond Hospital. Section 3. — Congenital malformation of the shoulder joint. — Although little can be done by medicine or surgery to alleviate, much less to remedy, the evils attending on congenital malformation of the shoulder joint, still it appears to us to be not the less necessary that the abnormal conditions of this articula- tion resulting from congenital defects should be studied. These, like some other congenital malformations of the joints, attract but little notice during the first months of infancy, hut as the child grows the defect becomes more manifest. It very commonly happens in these cases, that after some time the ordinary sur- gical opinions taken on the case, and the mea- sures recommended faihng, as they naturally do, to produce satisfactory results, the ill- fated patient, born with malformation of the shoulder joint, is subjected to ignorant and empirical treatment, the inutility of which too often proves to be the least of the evils attending it.* * About ten years ago the writer met in cousulta- tion surgeon W". Wilde on the case of an only child, a girl of thirteen years of age, who had a congenital malformation of the shoulder joint.presenting exactly the appearance of the joint '(/^r. 441.). The young lady is noAv twenty-three years of age, and the writer has been informed by one of her relatives. The most common form of congenital mal- formation of the parts composing the region of the shoulder joint that we have noticed, has been apparently the result of an arrest of development, and of atrophy affecting the muscles, the bones, and probably also the nerves of this region. Sometimes we find both shoulder joints are malformed in the same individual; generally one only is thus affected. In this last case the atrophied con- dition of the malformed joint is well seen on com[)aring the normal and abnormal shoulder: the latter is smaller than the former ; the muscles around the joint are so imperfectly developed, that the coracoid and the acro- mion processes and the head of the humerus become unusually conspicuous. The deltoid and articular muscles are so weak, and the capsule so loose, that the limb seems usually to be drawn down, as it were, by its own weight, and then becomes displaced forwards and inwards beneath the coracoid process, where it habitually remains, the head of the humerus forming a protuberance in front, which yields to the slightest force pressing it backwards towards the usual site of the glenoid cavity of the scapula. When the arm is taken hold of at its lowest extremity, as at the elbow, and drawn back- wards, the head of the humerus advances forwards and passes beneath the coracoid process, and a depression, corresponding to the posterior half of the glenoid cavity, is perceptible. On the contrary, when the elbow is drawn forwards, the head of the humerus recedes towards the normal site of the gle- noid cavity ; when the humerus is raised up perpendicularly towards the acromion, and the influence of the weight of the limb is thus counteracted, the shoulder appears of its natural form, but diminished about half the normal size. The muscles around the joint are so badly developed, that the bony process which surrounds it becomes very conspicuous. The accompanying drawing is designed to pourtray the general aspect of one of these cases of congenital malformation of the shoul- der joint in the displacement inwards of the head of the humerus (^Jig. 44L). Case. — The following is the history of the case from which the drawing has been taken. M. H., aet. 28, is in every respect healthy and well formed, except as to his left shoul- der, which, since his birth, has al ways been noticed to have been smaller than the other. This defect gives a peculiar appearance to his whole figure as he j^tands or walks. As his arm hangs by his side, the longitudinal axis of it is directed downwards and a little back- wards. The head of the humerus is a li;tle advanced as well as depressed beneath the outer margin of the coracoid process ; it is that she is in no respect better as to the condition of her shoulder joint ; but that her general health has suflered materially in consequence of the various treatment she had been subjected to in vain. Her parents, ignorant of the nature of the case, and too sanguine in their hopes, had been the easy dupes of charlatanism. &18 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. also slifrhtly adducted towards the middle the head of the humerus passes backwards line. When the shoulder is viewed posteriorly beneath the acromion, and a depression can a depression corresponding to the situation be felt in front beneath the coracoid process, of the posterior half of the glenoid cavity is corresponding to the portion of the abnormal observable : into this depression the finger can articular cavity which the head of the humerus be sunk so far as to reach the surface of the had just before occupied. The muscles of the posterior part of the glenoid cavity. When region of the shoulder are very imperfectly the arm is drawn forwards across the chest, developed, but those of the fore-arm and Fig. 441. Case of 31. H. — Congenital malformation of the left shoulder joint, with lujration of the head of the humerus inwards. hand seem of their normal size. The patient the arm vertically, the joint assumes more of has but little power of moving the affected a natural form. Still, independent of its com- upper extremity. The trapezius muscle of parative diminution of size, it wants the ro- this side is well formed, therefore he can by tundity and fulness of contour ordinarily de- means of its influence elevate on the side of rived from a proper development of muscular the trunk the whole limb. The deltoid and covering. The elbow joint is perfect as to capsular muscles are very imperfectly formed, its form and functions. This patient has and consequently the patient has no power been under the writer's observation for many of abduction, nor of rotation, of the humerus, years, and these symptoms have not varied. The shoulder has not the usual rounded form, Anatomical cha?-acters of congenital malform- but still it does not present the flattened ap- ation of the shoulder joint irith displace- pearance, nor the acromion the angular out- ment of the head of the humerus inivards. — line which characterises the accidental luxa- We may consider the following as a good tion of this joint. Yet the acromion process example, showing the anatomical characters of does project somewhat, and when the arm the congenital malformation of the shoulder hangs by the side, the head of the humerus, joint, icith displacement inwards of the head distinct and prominent, is removed so much of the humerus ; the congenital defect ex- from the under surface of the acromion, as it isted in both shoulder joints, were by the weight of the limb, that the Case. — " A female, aetat 28, who had been for thumb can be easily placed between them, many years a patient in the lunatic department When we take hold of the elbow and raise of the House of Industry, died of chronic in- ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 619 flammation of the membranes of the brain, and Dr. Smith* made the post-mortem ex- amination. Upon entering the room his attention was attracted by the appearances which the shoulder joints presented. The de- viations from the normal state were most remarkable at the left side. The muscles of the shoulder and arm were atrophied, the acromion process projected considerably, and the head of the humerus could be perceived lying a little beneath the coracoid process, the apex of which was in a line with the bicipital groove of the humerus. The na- tural roundness of the shoulder did not exist, and the elbow could be readily brought into contact with the side. The right shoulder joint presented similar appearances, but in a slighter degree ; the head of the humerus was not placed so directly beneath the coracoid process ; but the flattened form of the shoul- der, the atrophied muscles, and the projection of the acromion, all indicated that the condi- tion of the joint was nearly similar on both sides. From the last circumstance, and the absence of any external sign of disease, it was concluded that the deformities were the result of an original or congenital malformation. The anatowical examination of the joints confirmed this opinion. Upon the left side there existed scarcely any trace of an arti- cular surface in the situation which the gle- noid cavity occupies in the normal state ; but there had been formed on the costal surface of the scapula a socket of a gle- noid shape, measuring an inch and half in its vertical direction, and an inch and a quarter transversely. It reached upwards to the under surface of the coracoid process, from which the head of the humerus was merely separated by the capsular ligament, there being no interval between the summit of the abnormal socket and the coracoid pro- cess. Around this socket the glenoid liga- ment, perfect in every respect, was continued from the margin of that small portion of the natural articulating surface which existed upon the axillary margin of the bone, and to the apex of which the tendon of the biceps was attached. The capsular ligament was perfect. The head of the humerus did not present its natural spherical form ; it was of an oval shape, its long axis corresponding with that of the long axis of the shaft of the bone. The shaft of the humerus w^as small and seemingly atrophied, and the position of the bone with respect to the coracoid and acromion processes varied according as the motion of rotation inwards or outwards was imparted to the arm. During rotation out- wards in this case the head of the bone passed towards the acromion process, and occupied the small portion that existed of the glenoid cavity on the normal site ; while rotation inwards brought the head of the humerus altogether beneath the coracoid process, so that the finger could be easily sunk into the outer portion of the socket.f * Smith on Fractures, &c. t This species of locomotion of the articular head On the right side, although the condition of the bones was somewhat different, the cha- racteristic features of the deformity were similar. In this case it was ascertained, that there never had been any disease of either of the shoulder joints at any period of the patient's life, nor had they ever been the subject of in- jury or accident of any description. The position of the glenoid cavity in this case, beneath the coracoid process, the remarkable form of the head of the humerus, the presence of a perfect glenoid ligament, the absence of any trace of disease, and the existence of the deformity upon each side, all indicate that the nature of the malformation must have been congenital, although but little of the early history of the case was known. Congenital malformation of the sJionlder joints with displacement of the head of the humerus on the dorsum of the scapula. — The second case we think right to abstract from Dr. R. Smith's work is also a very important one, equally proving that a double congenital luxation of the head of the humerus may be observed to take place backwards on the dorsum of the scapula, just as we have already shown that Fig. 442. Congenital luxation on the dorsum of the scapula. an analogous dislocation forwards has oc- curred. of a bone representing the proper rotation which should exist, is a consequence of the existing lax state of the fibrous structures of the joint. "We have ah-eady noticed a similar condition of the liga- ments, and a similar effect, when describing a case of congenital malformation of the vadio-humeral joint. See Elbow Joint, Vol. II. note to page 81, where it is said — " These movements did not con- sist in a simple rotation of the radius on its longi- tudinal axis, but a real change of the upper extre- mity of the radius on the outer condyle of the humerus." J 620 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. Case. — A woman, named Judith Doyle, died upon the 8th of February, 1839 : she had been a patient for fifteen years in the lunatic department of the House of Industry ; was subject to severe epileptic convulsions, which were the cause of her death. While making the examination of the brain, the unusual ap- '3earance which the left shoulder joint presented accidentally attracted the author's attention. The head of the humerus appeared to have been dislocated on the dorsum of the scapula. Finding that the opposite shoulder presented precisely similar appearances, he had no hesitation in expressmg his opinion that the case was one of double congenita! Inxation of the head of the humerus backwards. The two shoulders resembled each other so perfectly, not only in their external conform- ation, but likewise in their anatomical cha- racters, that the description of one will be sufficient. The coracoid process, owing to the removal of the head of the humerus from its vicinity, formed a most remarkable projection, and the subject being emaciated, the coraco-brachialis Fig. 443. Congenital malformation of the left humerus. and the short head of the biceps could be seen passing very obliquely downwards and out- wards, and the anterior margin of the coraco- acromial ligament stood out in strong relief. The acromion process was unusually promi- nent, although it did not project as much as in any of the accidental dislocations of the shoulder. The glenoid cavity could not be felt, although the head of the humerus was so far removed from its natural position. The shoulder appeared higher than natural, and was flattened anteriorly ; but posteriorly a round, solid tumour plainly indicated the situation of the head of the bone placed on the dorsal surface of the scapula, hnmediately below the spine and posterior angle of the acromion. The head of the bone thus dis- placed could be seen and felt to accompany all the movements given to the shaft of the humerus. The transverse diameter of the shoulder was much greater than natural, the distance between the coracoid process and the external surface of the head of the humerus being three inches and a half; the arm was directed obliquely downwards and inwards ; the elbow was in contact with the side, and the hand and fore-arm in a state of prona- tion. Upon removing the muscles and ex- posing the interior of the joint, I found that there was no trace of a glenoid cavity in the natural situation ; but upon the posterior surface of the neck of the scapula there was a well-formed socket, which received the head of the humerus. It was an inch and three quarters in length, and one inch in breadth ; it was a little broader above than below, and its summit was less than a quarter of an inch from the under surface of the acro- mion process. It was directed outwards and forwards, was covered with cartilage, and sur- rounded by a perfect glenoid ligament. The tendon of the biceps muscle arose from the most internal part of its superior extremity, from whence it passed downwards and out- wards very obliquely, in order to reach the bicipital groove of the humerus. The axillary margin of the scapula, if pro- longed upwards, would have passed nearly altogether internal to the abnormal socket. The surfaces of the acromion process had not their normal aspects, but looked directly upwards and downwards, being on the same continuous plane with the surfaces of the spine of the scapula that contribute to form supra- and infra-spinatus fossa ; a circumstance in itself sufficiently showing that the mal- formation was congenital, and not altogether limited to the shoulder joint itself. The capsular ligament was perfect; the scapula was smaller than natural, and its muscles badly developed. The head of the humerus was of an oval form on the right side, somewhat broader above than below; its anterior half was in contact with the glenoid cavity : this portion was covered with cartilage, the re- maining half being rough and scabrous, and destitute of articular cartilage. The greater tubercle was normal as to form, but the lesser was elongated for the extent of one inch, and curved upwards, forming a concavity on its upper surface to receive the tendon of the biceps ; on the left side, the head of the humerus presented almost similar appear- ances. The hypertrophy of the lesser tube- rosity, Mr. Smith observes, appears to ha\e been the result of a process established to counteract the danger to which the very oblique course of the tendon, with regard to the muscular fibres, exposed it. The history of this case, so far as the mo- tions which the head of the humerus was ca- pable of performing, is not known ; but we may conclude from the post-mortem examination, that there was here a complete congenital dislocation on the dorsum of the scapula. A well-formed ?:ocket existed on the dorsum of the scapula, upon which the head of the humerus was permanently lodged ; it did not shift its position during the motions of SIXTH PAIR OF NERVES. 621 rotation, as was mentioned to be the case in the former example. We must agree with the author that the phenomena noticed in this rare and remark- able case originated neither in disease, nor were they the result of accident. The com- plete absence of a glenoid cavity in the nor- mal situation for it, the existence of the malformation on both sides, the perfect resemblance to each other of the abnormal sockets, in form, size, and position, the in- tegrity of the tendon of the biceps and of the capsular and glenoid ligaments, and the pe- culiar form of the head of the humerus, as well as of the acromion process of the sca- pula on each side, all support the opinion that the malformation was intra-uterine and con- genital. (^Robert Adams. ^ SIXTH PAIR OF NERVES. Le Sixieme Nerf, Fr. ; Sechster Nerv, Germ. According to the enumeration of Willis, this name is bestowed upon a single soft round cord, which is, with the exception of the fourth, the smallest of the cranial nerves, and which, passing forwards from the medulla oblongata to the external rectus of the eye, finds its distribution in this muscle. The anatomy of this nerve is readily sub- divided into three portions. The first of these extends from its apparent origin to the point where it enters the cavernous sinus ; the second includes its course in that cavity ; and the third, commencing at the sphenoidal fissure or foramen lacerum anticus, contains the course of the nerve in the orbit, and is terminated by its distribution. The visible origin of the nerve is by one or two bundles from the medulla oblongata, from the anterior pyramid of which it ap- pears at its upper part, or in the transverse depression immediately behind the posterior border of the pons varolii. By careful dis- section, the nerve can be traced into the sub- stance of this anterior column, and, appa- rently, it passes through it towards the grey matter which more deeply surrounds this tract of the medulla. Further than this it is impossible to follow it satisfactorily, although some anatomists have, with Mayo, assigned to it a yet deeper origin. In the first part of its course the nerve passes forwards, upwards, and outwards for a very short distance, from near the median line to the posterior extre- mity of the cavernous sinus which forms the commencement of the inferior petrosal sinus. In this course it Hes upon the concave basilar surface of the sphenoid bone, and is covered above by the projecting pons varolii ; and at the front, where it leaves the interior ol the skull, the arachnoid membrane is reflected around it. It next passes through an opening in the dura mater, and enters the cavity of the sinus. This aperture is situated just in- ternal to the tip of the petrous bone, and is about one-third of an inch anterior to the orifice of the fifth nerve, bnt on a rather lower level. On entering the sinus, it is somewhat curved or bent into a more horizontal direction, and crosses over the posterior or vertical part of the carotid artery, which here experiences its sigmoid bend by the side of the body of the sphenoid bone. It next lies parallel to, but beneath, the horizontal part of this vessel, and passes almost directly forwards, through and amongst the numerous reticulations which occupy the cavity of the sinus, but it is covered by its lining membrane. At the anterior extremity of the cavernous sinus it enters the orbit by passing between the two heads or processes of origin of the external rectus muscle. Since the nerve in this course lies within the sinus, it is internal to the three nerves, viz. the third, fourth, and the ophthalmic division of the fifth, which are situated in the dura mater forming its outer wall. Poste- riorly, the lowest of these, or the ophthalmic nerve, lies on much the same level, but nearer to the sphenoidal fissure. The latter nerve having passed upwards, the sixth is left again occupying the most inferior and internal position of all the nerves w hich pass through this orifice, the lower division of the third being to its inner side, and somewhat superior to it, whilst above this is the nasal branch of the fifth. Below the sixth nerve, the oph- thalmic vein perforates the dura mater of the sinus by a separate aperture, In the cavernous sinus, the following branches are connected with, or come from, this nerve : — 1. It is connected with the sympathetic nerve by several filaments. Two of these are of considerable size, and may be traced back- wards at rather an acute angle from the trunk of the nerve, to join those numerous rami- fications of the sympathetic which constitute the carotid plexus surrounding the artery in this venous cavity. 2. An anastomosis, or junction with the ophthalmic branch of the fifth, is described by most anatomists, and may be readily verified in the recent subject. One or more branches, having very much the same direction and ap- pearance with the preceding to the sympa- thetic, pass backwards from the sixth nerve, in the anterior part of the sinus ; leaving it at a very acute angle, inclining outwards as they go, and finally, entering the wall of the sinus to join the ophthalmic branch, not far from the Gasserian ganglion. These branches also exist in the sheep, and some other of the lower animals.* * A very similar description might be extended to the analogous junction of the fourth nerve with this division of the fifth. Thus, in the sheep, three or even four considerable branches leave the ophthal- mic nerve at an acute angle to join the fourth nerve. They effect this junction very obliquely, and may be traced forwards (distad ) for at least some distance. May not some of these filaments, traced backwards from the fourth nerve to the wall of the cavernous sinus, which they enter to join the ophthalmic division, have been the ^entormZ branches of Bidder, which he describes as coming from the former nerve to be distributed to the dura mater of the tentorium ? 622 SKELETON. 3. Avery fine filament from the sixth nerve to the ciliary or lenticular ganglion has been described by several authors. Subsequently to the cavernous sinus, the course of the nerve is but short. Arriving at the posterior extremity, or apex of the orbit, the nerve lying to the outer side of that part of the third which supplies the inferior rectus and oblique muscles, runs slightly upwards, and turning oiitw-ards, continues for a very short distance along the inner surface of the external rectus. It finally breaks up into numerous minute filaments, which enter the ocular surface of this muscle to be distributed to it. Physiology of the sixth nerve. — The function of the nerve is, perhaps, sufficiently indicated by the preceding tletails. Since anatomy shows that its terminal distribution is exclusively to a muscular surface, w^e should on this ground alone be tolerably entitled to predicate its motor function. The little that is known of its comjjarative anatomy confirms the inference. In all the higher vertebrata it is distributed to the ex- ternal rectus. In some, however, it experi- ences an enlargement, and a further distribu- tion. The muscle which sweeps the broad nictitating membrane over the bird's eye, and the funnel-shaped, or choanoid muscle which surrounds the 0{)tic nerve and eyeball of many mammalia, are both supplied from this nerve. So also one or two cases are recorded, in which an injury of this nerve from disease in the neighbourhood has produced paralysis of the external rectus, and an inward squint. While, vice versa, the experiment of galvanising the nerve has been accompanied by violent contractions of the muscle, and an external strabismus. The insensibihty of the nerve is, perhaps, less certain than might at first appear, though Longet* distinctly states that pinching the nerve at its origin is unattended by signs of pain. The branch of junction with the oph- thalmic nerve seems to be, from its direction and appearances, much more like a filament from the sensitive to the motor nerve, than from the latter to the former. If this be the case, they would seem to be somewhat ana- logous to the junction of the numerous branches of the fifth with the portio dura on the face. And in the absence of direct ex- periment upon the nerve beyond the seat of this union, one might conjecture it as possible, that the sixth nerve was possessed of a slight sensibility similar to that of this portion of the seventh. Concerning the import of the junc- tion with the sympathetic, little can here be said ; for although, as compared with the size of the communicating nerves, this union is larger than most others, yet there does not seem any sufficient reason for supposing other differences. The distribution of a branch from the sixth to the ciliary ganglion has been thought by Longet and others to explain the persistence * Sur le Systeme Xen'eux. of movements of the iris after paralysis of the third nerve. But besides that the constant existence of this filament seems hardly veri- fied ; perhaps the interposition of a ganglion between the paralysed nerve and the ciliary filaments might alone be thought a sufficient explanation of the inconstancy or imperfec- tion of the result, without requiring the ex- istence of another and an uninjured channel as the cause. Bibhograj)hy. — See *' Nerve." (JVilUam Brinton.) SKELETON. — The name skeleton, cxe- \sTov, formed from (r^f^Xw, to dry, is, in anatomy, ordinarily applied to denote that assemblage and arrangement of all the osseous pieces of an animal framework in such con- nection and relationary order as the hand of nature has disposed them for fitting operation in the living body. The less the name skeleton impresses the mind with the configuration of any particular form of the osseous machines, the better is it fitted as an abstract general title, under which to give a comparative survey of all figures of the osseous system, whatever be their special characteristics ; and this abstract survey being my present purpose, I find that the name skeleton, devoid as it is of any direct and inconvertible meaning, conveniently ex- tends itself over all varieties of the osseous fabrics of the four higher classes of animals ; from the mutual comparison of which I shall strive to elicit the law which creates them in the character of a tmity in variety *, a condi- tion of form by which the many species gather themselves together naturally into a circle and point to some unknown oneness of character which enchains them the one to the other. This law of unity in variety is still uninter- preted ; and though it formed the moving theme of the great Grecian naturalist f three thousand years back, and afterwards lay in cold obstruction till resumed in later times by Leibnitz, Newton, Buftbn, Cuvier, GeoffVoy St. Hilaire, Oken, Goethe, Carus, Owen J, * Leibnitz makes use of this phrase as being the general expression of his ideas of that condition of development manifested throughout the animal kingdom, namely the condition of an all-encom- passing structural analogy which relates organised beings more or less closely to one another. His " loi de continuite " is founded likewise upon the same general fact. He defines the universe as " I'uuite dans la varie'te," and of the animal king- dom he writes, *' tout va par dcgre's dans la nature, et rien par saut." See (Euvres Philosophiques de M. de Leibnits, liv, p. 440. t Aristotle, the great founder of generalisation in the physical sciences, Avas strongly impressed with the common resemblances or analogies of ani- mals, and expresses the tact as follows: — "But some animals neither have parts specifically the same, nor the same according to excess and defect, but according to analogy." History of Animals, book i. p. 4. trans, by Taylor. X The late work of the leamed Himterian profes- sor, entitled " Homologies of the Vertebrate Skele- ton," contains, in addition to his own especial Anews, a complete account of all that has been AATitten upon the subject of skeletal analogies by the leading com- SKELETON. 6-23 Grant, and others, still does it remain as an open arena of inquiry, courting the votary of truth to enter there and allure her from her se- cret covert. All that has been written has not fixed the Protean interpretation of this law which governs the developement of vertebrated skeletons. Since, therefore, this theme (upon which so many great inquirers have assa}'ed interpretations which conflict with each other, and in the struggle lose the clue of truth), even to this hour fails of the culminating idea, and is by so much imperfect, of what avail would it be to the reader or myself were I to discuss the merits of the various opinions such as they stand? Rather than dispute about opinions, I shall turn to the facts themselves, upon which those opinions have been grounded, and engage at once in the comparison of facts as facts independent of all opinion respecting them, and unmindful of the names * by which they are liable to be mistaken for what they are not. Under the abstract term skeleton, I shall take a general survey of the whole subject of comparative osteology ; and if the reader chooses to call this survey " transcendental," I shall endeavour to show that it shall not be visionary. My argument shall set out from a first proposition, through a successional en- chainment of propositions ; and in the matter of all the propositions taken collectively, I shall body forth an interpretation hitherto un- known in anatomical science. The facts and their proper interpretation may be fairly termed the body and soul of truth, and such a truth is a compound of the actual and the in- tellectual. The facts themselves give evidence to all observers of the truth of " unity in variety," but it is by inductive reasoning that the intellect is to interpret the law, the poten- tial agency, by which the same facts are at the same time uniform and yet various. The object which I shall keep in view while constructing my comparisons, is to demonstrate the figure of unity, and give interpretation to the figures of variety which are sprung of it. To this end I shall prove, — 1st. That all the osseous skeletal forms are quantitatively unequal things. parative anatomists of the German and French schools. To this work, and the principle which the author endeavours to establish, I shall frequently refer ; and believing (as all who shall study that work must believe) that the meritorious object of its distinguished author is to give creation to a great truth in science, at the same time that he is not unwilling to give ear to all counter-argument rationally advanced, I shall therefore not hesitate to question the principle set forward in the work, as freely as shall serve my own purpose, which holds the like object in view. In whatever points, there- fore, I may take objection to the author's reading, and in doing so may appear too rash to question so great and philosophical an authority, it is the cause which must be my excuse. * " This, if we rightly consider and confine not our thoughts and abstract ideas to names, as if there were or could be no other sorts of things than what known names had already determined and, as it were, set out, we should think of things vnth. greater freedom and less confusion than perhaps we do." Locke, Reality of Knowledge. 2d. That they are the unequal quantities of a greater or archetypal form *, a unity which has undergone such an infinitely graduated metamorphosis of its parts as to yield these unequal skeletal forms. 3d. That the law of formation is one of degradation of an archetypal uniform original. 4th. That these unequal skeletal forms con- stitute the species or varieties of the unity of the archetype. 5th. That the whole or archetypal form of which these unequal skeletal figures are the parts, is the only absolutely uniform skeletal series. 6th. That nomenclature and all modes of classification, according to specific distinct- nesses, have no real meaning apart from the consideration of this law of an archetypal uniform prime model undergoing a graduated metamorphosis of its parts. That in this higher law of graduated series is enveloped all lesser laws of classes, orders, genera, species, and individuals, which, whatever be the amount of their distinctive characters, do one and all point to a unity of type more or less. With this purpose before the reader's mind, I proceed to lay down my propositions as preliminaries by which to pioneer a passage through the blinding thicket of nomencla- ture and gain the light beyond it, the light of a general law f in nature. But before he * This term, archetype, having been first intro- duced by me in the study of comparative osteology, may require here a word in explanation. When I first applied myself to the study of the law of " unity in variety " which presides over the de- velopment of vertebrated skeletons, there appeared to be such a shadowy and ill -defined meaning in the term unity in variety, and the facts of form themselves presented in such a mysterious condition of enchained analogous characters, and at the same time gave such immistakeable e\idences of an en- chained specific diversity, the latter encountering the former condition at every step of inquiry, and neither the diff'erences nor the analogies (while contem- plated as such under the same regard) holding forth to me Siwy promise of an end to labour and research, that I at length resolved to know (in addition to the self-evident analogy which the facts manifested) whether or not the deferential properties were mainly owing to some law which degraded or pro- portioned the lesser and special forms from some greater or Avhole form — some integer or full skeletal figui-e which might be seen as containing in its omti quantitative character the sum of all knoAvn varie- ties or species. The comparative method which I adopted to define the existence of such a figure realised my expectation, as I shall presently show, and to this figure I gave the name archetype. In a paper " On Anatomical Nomenclature," ad- dressed to Professors Owen and Grant, published in a number of the Lancet, March, 14. 1846, I have spoken of the figure of an archetype skeleton. About the same time that I since published my work on " Comparative Osteology and the Arche- type Skeleton," bearing date 1847, I felt gratified to see that the learned Professor Owen sanctioned the name archetype, and gave it the weight and interest of his philosophical researches. See his work, en- titled " The ArchetjqDC and Homologies of the Ver- tebrate Skeleton," published 1848, being a second edition of his work bearing the same title, published 1847. t " Les lois, dans la signification la plus etendue, sont les rapports necessaires qui de'rivent de la 624 SKELETON. passes with me to my task of comparison, I warn him that he should feel within himself a full conviction of the truth, that in order to gain a fair insight of the law of formation, he must not suffer names of different significa- tions to hide the common analogy or sitnilitude which the things themselves manifest. He must have fully freed himself of the barbarisms of the nomenclature which the unreasoning human anatomist still makes use of ; he must not suppose that because one spinal piece is named sacrum, it is therefore absolutely dif- ferent to another spinal piece named vertebra. And even in respect to the name vertebra*, which applies alike to all spinal segments, however quantitatively different these may be, he should not think these the same things in form and dimensions, and elemental consti- tuents, simply because they bear the same name. For in reality this name vertebra attaches to bodies which are quantitatively different, and is, therefore, a name as truly misapplied to generalise not only over the spinal units of the skeletal axes of the four classes of vertebrata, but even over those of the human type ; as if, \Ahile viewing a series of circles, semi- circles, and segments, we called it a series of segments of semicircles or of circles, which it evidently is not. We would not call the two quantities, viz. circle and segment, by the same name ; neither should we name such different quantities as cervical, dorsal, and coccygeal forms under the common title " vertebrae." If we fully ackowledge to this first truth, truth will be begotten of it ; but if we still begin the calculation with the error, error will spring from out of it, and defy all mathematical computation. Proposition I. VcrtebicB are unequal quan- tities.— In the human spinal axis I find that those bodies which the human anatomist terms vertebrae are not quantitatively similar, equal, or homologous.f The cervical vertebra (a,^^. nature des choses." Esprit des Lois, lib. i. eh. 1. Montesquieu. * Lamarck originated the name vertebrated, as characterising one great division of the animal kingdom, — " Les animaux vertebres," from the other " Les animaux sans vertebres." But comparative osteology, as studied in the present time, has ahiiost rendered this name obsolete, incapable, as it evi- dently is, to be the instrument where^vith to gene- ralise the skeletal frameworks of the four classes of animals. Even the originator himself seems to have entertained a doubt as to the efficiency of the name, or any mode of classification, or method, or nomenclature used in subdividing the continuity of the chain of nature. He writes, " Mais j'ai deja montre qu'il est un produit de Fart, et que malgre' les apparences contraires il ne tient reellement rien de la nature." See Philosophie Zoologique, torn. i. chap. V. t This term " homologous," as used by the geo- metrician, means corresponding. Figures are called similar or corresponding whose sides and angles are homologous. Quantities having the same manner or proportions are homologous. Quantities, there- fore, which are not equal to one another are not homologous ; but such quantities, though being un- equal, may still possess the correspondence Avhich we see apparent in the proportionals of a whole quantity j thus a segment of a circle or a semicircle, 4 1 k) differs in this respect from the dorsal ver- teora (c) ; this from the lumbar vertebra (e); Fig. 444. Vertebres of the human spine. Showing a quantitative difference. The similar parts of each bear the same figures. this from the sacral vertebra (h); and this from the coccygeal vertebra (i). In all ani- mal spinal axes 1 see that those bodies which the comparative anatomist names vertebrae are likewise quantitatively different. The several classes of vertebrae termed cervical, dorsal, lumbar, sacral, and caudal, are actually deve- loped of unequal quantities. And it is, more- over, most true that even the vertebrae of any one class, whether of the cervical class, the dorsal, lumbar, sacral, or caudal, are not quantitatively similar or equal. In animal cer- vices, thoraces, or loins, the vertebrae consti- tuting any of those regional divisions of the spinal axis are not equal quantities. Even in though not equal to the circle, manifest a propor- tional correspondence all three ; and in the same way, vertebral quantities which manifest to each other a similar degree of proportional correspond- ence, seem to point to some unknown whole quan- tity of which they are the parts. Philosophical anatomists seem to have all agreed upon the point, that the name vertebra attaches to certain osseous forms arranged along the spinal axis, Avhich, in fact, are proportionally diverse bodies, and being so acknowledged, they have directed comparative re- search to determine the quantitative form of the " typical vertebra." The difficulty of this inquiry into the form and quantitative character of the typical vertebra may be learned from the fact, that science has not, as yet, determined it upon the finn basis of demonstrative evidence. SKELETON. G25 the human cervix, thorax, or loins, or sacrum, or caudex, the vertebras of each region mani- fest those quantitative differences. For we find in the human neck that b, or in the loins F, occasionally develops a sur{)lus rib (^5'.444. B and f, 4); which circumstance gives rise to a serious objection to the rule, that " the mammal cervix is constant to the num- ber of seven vertebrae," or that the thorax of even the human skeleton develops twelve vertebrae constantly, or that the human lum- bar region is confined to the number of five vertebrae constantly. It is evident, therefore, that the bodies named vertebrae are quantita- tively different bodies, as seen not only in all spinal axes comparatively estimated, but even in the one animal spine of human type. Prop. II. Evoi the one vertebra is not of equal quantity in all individuals of the same species. — Comparative research proves that all vertebrae are quantitatively unequal entities ; but this is not all, for even when I fix attention upon the single isolated vertebral segment of the spine, I find that it manifests a fluctuating character as to proportions and elementary quantity. The seventh cervical vertebra (a. Jig. 444.) of the mammal spinal axis occasion- ally produces a costal appendage (4 of b). The first lumbar vertebra (e,j%. 444.) of the human spine likewise develops now and then the costal appendages (4 of f, fig. 444.) ; and hence it is that anatomists are still unde- cided whether to name them thoracic vertebrae or not. I do not here intend to discuss those several interpretations which anatomists have advanced concerning the cervical and lumbar ribs, for we should find ourselves in the end as little enlightened about the true nature of the anatomical fact as when we first set out, suffice it here that we fully own to the fact ; that the body which we name vertebra is not always equal to itself at all times even in the one fixed locality of the spinal series. Prop. III. All vertebrce contain a greater or lesser amount of certain knoivn elemental pieces. — If we will consider why it is that we de- signate vertebral bodies under one generalising appellation, we will find that it is on account of vertebrae (whatever be their special variety) containing few or more of those elemental nuclei from which vertebrae are fashioned. Thus as we find vertebrae to be constituted from a whole sum of elementary pieces proper alone to vertebral form, we therefore consent to give the name vertebra to every spinal figure which shall produce any one element proper to the ideal vertebral type. But then we must not understand by this name vertebrated, a con- dition of absolute quantitative uniformity* * Tl>e uniformity of a serial line of bodies im- plies that all units of the line of serial order are quantitatively equal and homologous. A series of circles would constitute such an unifortnity, because all such circles would be similar. L^ni- formity, taken in this sense of equality among the units of the series, does not characterise the verte- bral spinal series ; but while we see that vertebrae, though not uniform as quantities, are still various only as proportionals of a greater ens or archetype, then the question arises as to how these propor- VOL. IV, throughout the bodies so named ; for to do so would be as directly opposed to natural evi- dence as to understand by the name cndo- skeleton, that all figures so named were abso- lutely uniform with each other in quantity. The truth is that vertebrae are as much varied to each other as skeletons ; but the truth also is that vertebrae are only quantitatively differ- ent, just as skeletons are. A coccygeal vertebra (i,/g.444.) is only different from a lumbar (f,e) or cervical vertel)ra (a, b) by quantity ; and a skeleton of a frog is different to that of a whale by the condition of variable quantity also. But a coccygeal vertebra {i,^/ig- 444 ) is in reality a vertebral centrum (o) unattended with the presence of those other elementary pieces, such as laminae marked 2, 2, spinous (1), and transverse processes (3), which else- where constitute the completer vertebral form ; and hence it is to be inferred that a coccygeal vertebra is a minus quantity, and as such dif- fers in this respect only from a lumbar or cervical vertebra ; these latter being pins in those very same elements which the coccygeal vertebra wants. It is sufficient for us at pre- sent to know clearly that all vertebrae have some elements in common, and that the only difference which appears between them is occurring by a simple omission of elementary parts from some vertebrae, which parts are present and persistent in other vertebrae. The coccygeal bone (i, 444,), being as a vertebral centrum (a) identical with the centra marked 5 in all other vertebra, is different from all other vertebrae simply by the loss ot parts ; and those parts which it has lost are evidently such parts as I find in a vertebra elsewhere posited, viz. the parts marked 1, 2, 3, 4. Prop. IV. The dorsal vertebra of human anatomy is an artificial figure. — The hunian anatomist separates the dorsal vertebra (c, fig. 444.) from its costal appendages marked 4 in D, fig. 444., and by so doing he discon- nects forms which nature has created inse- parable from each other. In nature there is no such ens as the dorsal vertebra (c, fig. 444.) developed without the ribs (4 of d.) ; nor can we conceive the idea of a dorsal ver- tionals have had creation ? It is evident that the solution of this question is attainable only by a rule of equation, which, Avhile it acknowledges the con- dition of the proportional, or the a—b, must fill up or supply mentally (without deference to the doctrine of functional fitness) the ditferential quantity which is to equate it Avith a+b ; and this is the mode which I adopt, in order to re-establish the original typical uniformity of skeleton bodies, for 1 shall p'rove that the known quantitative dili'crence be- tween two unequal fonns renders them equal in idea. The typical skeleton of Carus and Owen is an ideal creation, sprung from a rule of comparison which rejects (as I mean to do) the teleological doc- trine of Cuvier, and undertakes to compare form as form, regardless of the difference as to function. The paramount necessity of this ^ill at once occur to the reader, and he will recognise in the truly philosophical researches of the Hiuiterian professor an advance towards the truthful interpretation of the law of formation, equal in degree to the measui'e of this mode of comparison adopted by him. S S 626 SKELETON. tebra naturally independent of its costa.* When we bisect the circles we make semi- circles ; but by so doing we cannot possibly lose sight of the fact, that both semicircles -once constituted the whole circle ; and in the same way, when we separate the dorsal ver- tebra (c) from its attendant ribs (4 in d), we cannot obliterate from the memory the idea, that the dorsal vertebra and its ribs once formed an entire osseous quantity as that re- presented by D, having the ribs appended. When the human anatomist separates the dorsal quantity (c, fig. 444.) from the costal elements 4 in d, and describes the quantity of c as a vertebral figure, he commits an error no less visibly opposed to natural evi- dence than if he separated one half of the dorsal element from the other half, and called either half a vertebra. The dorsal vertebra (c) of human anatomy is therefore insepa- rable from its thoracic ribs (4 of d), and to these several pieces naturally combined and collectively contemplated (in d), I give the name costo-vertebral quantity. Prop. V. The cervical vertebra develops the costal appendages also. — In order to prove in- contestably that the anterior moiety (4) of the Fig. 445. A, dorsal vertebra ; b, cervical. transverse process (4, .3,^/%. 445. b), is the true homologue of the thoracic rib {^,fig. 445. a), I * I call the reader's attention particularly to this fact, as a starting point from which I set out with my argument, which is to conduct to the recog- nition of what I call whole quantities in the skeleton axis. It will be seen afterwards, that owing to this first error of the anthropotomist arbitrarily severing the ribs from the dorsal spinal centre, and giving to this latter the name vertebra, much con- fusion has arisen in the comparative method and its inferences. " Errores radicales et in prima digestione mentis ab excel) entia functionum et remedioi-um sequentium non curantur." Xo%'um Organon Sci- entiarum, Aph. 30. shall lay down my remarks as follow : — I se- parate from the human spinal axis that body (c,fig. 444.) which the human anatomist terms the " dorsal vertebra ; " and on comparing it with the cervical vertebra (A,/g. 444.), I find that both figures are identical as to the number and position of their elemental pieces in all respects save one particular. This one point in which the cervical vertebra (A,fig. 444.) dif- fers from the dorsal vertebra is evidently the anterior moiety (4) of the transverse process of the cervical vertebra (a) ; for the dorsal vertebra (c), such as the human anatomist describes it, does not contain any elemental piece as the true counterpart or homologue of the clement (4) which is posited as the an- terior half of the cervical transverse process.* In both vertebras (a, c, fig. 444.), I find the spinous elements marked 1, the laminae or neural arches (2), and the bodies or centra (5) ; but it is attaching to the transverse pro- cesses of both vertebras that a doubt arises as to their identity. Now if I call the posterior moiety (.3) of the transverse process of fig. 445. B, the true homologue or counterpart of the dorsal transverse process {fig. 444. c, 3), I still have no element in the dorsal ver- tebra (^g. 444. c), wherewith to compare the anterior half (4) of the cervical transverse process of fig. 445. b. But when I apply the costal piece (4,^g. 445. a) to the dorsal vertebra, constituted of the pieces 1, 2, 3, 5, then it becomes evident that this costa is supplying the place of the anterior half (4) of tlie cervical transverse process {fig. 445.). * AH anatomists (the comparative as well as the human) had, until lately, overlooked the compound nature of the transverse process of the cervical vertebra ; and even when this character of the pro- cess came to be fully acknowledged, still so difficult was it for them to emancipate themselves from the toils of the original error committed by the anthro- potomist, that we find them more willing to bend the stubborn facts of nature in accordance with the error, than to correct the oversight. Thus, agree- ably with the artificial vertebral quantity of the human anatomist's " dorsal vertebra," whose trans- verse process is single, that of the cervical vertebra being double, both processes were held to correspond nevertheless ; and consequently, when such a fact as that of the anterior nucleus of the cer^^cal trans- verse process being produced to the dimension of a cervical rib appeared, they, with Meckel, inter- preted this as a prolongation of the cer\-ical trans- verse process, which they had already regarded as homologous vrith the process so named in the dorsal vertebra : or with Blainville, they acknowledged its costal character and proportions, but interpreted it as belonging to a " category of ribs proper to themselves," distinct from those of the thorax, and also diverse to those called " cer-vical ribs " in other classes of animals. And although it had been broadly asserted, long since, by Hunauld, Santli- fort, and others, that the transcendental law gave to even the human skeleton more than twelve pairs of ribs — the supernimierary ones which now and then stood upon the cervical and lumbar vertebrae — still, owing to the obstructiveuess of the pre-con- ceived doctrine of the mammal cervix being ac- counted limited to the nmnber of seven ribless vertebrse, even nature herseh" failed to prove the invalidity of that general rule, though she presented them with the sloth's cer\-ix, Avhich produces nine vertebra, and that of the human species occasionally producing only five or six. SKELETON. 627 And it cannot be doubted, for 'a moment, that both these elemental pieces, marked 4 in both figures, are identical ; for many facts go to prove it : first, both elements marked 4 are posited in the same situation with re- spect to the other pieces (3, 2, ], 5) of the vertebrae; second, both are autogenous, that is to say, they are developed as sepa- rate and isolated deposits ; third, they hold the same serial order in the spinal axis ; fourth, the anterior element (4) of the cervical transverse process (^g. 445. b), is that which is occasionally converted into a rib, as seen in B, Jig. 444., and thereby simulating more closely the thoracic rib (4) of the dorsal verte- bra {Jig. 445. A.) ; fifth, a negative evidence may be adduced to prove that the anterior half (4) of the cervical transverse process of fg. 445. B, is the true counterpart of the tho- racic rib (/%. 444. b,4) ; for the more clearly it can be shown that the posterior half (3) of the cervical transverse process of Jig. 445. b, is the homologue of the dorsal transverse pro- cess {Jig. 444. c, 3), the more evident must it appear that neither one or the other of these last-named pieces are homologous to either of the two former ; sixth, the posterior half (3) of the cervical transverse process {Jig- 445. b) and the dorsal transverse pro- cess {Jig. 444. c, 3) are ''exogenous " growths ; that is to say, they are produced of ele- mental nuclei common to them and the *' neural " * or laminar arches marked 2 ; and therefore it appears that the cervical vertebra {Jig. 445. b) possesses a costal element (4), just as the dorsal vertebra (/g.445.A) does, the only difference between these vertebrae being, that the costa of the latter is produced of greater dimensions than the costa of the former. Prop. VI. All the cervical vertebrce develop costal appendages. — The identity which has been proved to exist between the seventh cer- vical vertebra and the first thoracic costo-verte- bral quantity will allow it to be inferred, that all the cervical vertebraj,the atlas not excepted, which are fashioned of an equal number of elemental nuclei, must therefore be identical with all the thoracic costo-vertebral quan- tities. The only difference which exists be- tween the cervical vertebrae, even that named atlas {Jig. 446.), and the thoracic costo-ver- Fig. 446. tebral quantities {Jig. 444.) is one of quantity ; and this difference in quantity appears upon comparison to be alone attaching to the costal * This term, " neural arch," is used by Professor Owen, from whom the term originates. " By " neural arch, I mean both neui-apophysis and neural spine, or the totality of the distinct parts of which such arch is composed." Homologies of the Vertebrate Skeleton, p. 190. appendages marked 4. — The thoracic costae are of larger dimensions than the cervical costae. Prop. VII. The lumbar vertebra develops the costal appendage. — When I take the dor- sal vertebra {c,Jig. 444.) (of human anatomy) separated from its costae, and hold it in comparison with the lumbar vertebra (r. Jig. 444.), I find that the elemental nuclei of both are, for the most part, equal in num- ber and similar in position and shape. The points by which anatomists doubt their ab- solute identity are the processes (3 of c and 4 of e), named " transverse" in both, and the process (3 of e) named *' tubercle " in the lumbar form. The cause of this doubt I find to be occasioned by an error as to the identity of elementary nuclei, and a consequent mis- application of terms. The cause of the anatomical error originates with human ana- tomy having described as a complete dorsal vertebra that figure (c, ^g. 444.) which has never been seen separate from its ribs, as it appears in T>,^g. 444. The best mode, there- fore, whereby we may correct this error, is to take nature as she presents to us, and inter- pret her by her own evidence, not through the artificial system of any "human invention. While I compare the first lumbar vertebra {Bfjig. 447.) with the last costo-vertebral tho- Fig. 447. racic form {x^Jig. 447.), I discover that nature has developed them of the same elemental pieces. In both the spinous element (1), the neural or laminar elements (2), and the bodies or centra (5), are apparent. In both are to be traced the true transverse processes which are homologous to each other in every re- spect, I mean the process named " tubercle " (3) of the lumbar vertebra (b), and the pro- cess named " transverse " (3) of the thoracic figure (a). Both these processes are identical in form, mode of growth, relative position in regard to the other vertebral elements (1, 2, 4, 5), and in serial order with regard to each other. They are the true transverse pro- cesses by every anatomical proof, for they are produced of elemental pieces common to them 628 SKELETON. and the neural arches (-2). — They are " exo- genous." Now the thoracic rib (4 of a) is also the true homologue of the lumbar mis- named and mistaken " transverse " process (4 of b), for both these structures are iden- tical in every respect : 1st, they hold the same serial order ; 2d, they are posited in the same situation with respect to the other ver- tebral elements ; 3d, they are autogenous ; 4th, the so called " transverse process " (4) of the lumbar vertebra (b) is that very struc- ture which occasionally presents to us in arti- cular costal form and function as seen in 4 of F, fg. 444., thereby more closely be- coming assimilated to the thoracic rib of the dorsal vertebra ; 5th, by negative evidence it may be shown that the thoracic rib (4 of a) is the true homologue of the so named trans- verse process (4) of the lumbar vertebra (b), for while it stands manifest that the " tuber- cle " (3) * of the latter is counterpart of the transverse process (3) of the dorsal vertebra, then it must follow that the thoracic rib and the lumbar " transverse process " "j" so called are also counterparts. The lumbar vertebra therefore produces the costal appendage.j Prop. VIII. All the lumhar verlehrcr. develop costal appendages. — That which is true of the first lumbar vertebra and the last costo- vertebral thoracic form must be true of the five lumbar vertebrae and the twelve thoracic costo- vertebral forms, for all the lumbar vertebrae are fashioned of an equal number of elementary pieces. The difference which exists between lumbar vertebrae and thoracic costo-vertebral forms is one of quantity, and the costal ap- pendages of both are those which show this quantitative diflference. — The ribs of the thorax are proportionably larger than those of the loins. In the thorax the costae (4 of a, j%.447.) a[)pear articularly connected with the centrum (5). In the loins the costaj (4 of b, Jig. 447.) are fixed or anchylosed to the ver- tebral centrum (5); but this state of anchy- losis is by no means constant ; and when they articulate freely with the centra of the lumbar * The " tubercle " is, in human anatomy, ac- counted as a process specially characterising the lumbar vertebra as distinct from the dorsal vertebra, in which latter the tubercle is supposed to have no counterpart. t Cruveilhier states, as a peculiarity,of the lumbar transverse process, that it sometimes remains arti- cularly separate, and simulates the costal character, becoming the " supenimnerary rib." Meckel alludes to the fact also. X On referring to the " Homologies of the Verte- brate Skeleton," I find the following afiirmation : — " Each of the five succeeding segments is repre- sented by the same elements (centiaim and neural arch) coalesced, that constitute the so called dorsal vertebra ; they are called ' lumbar vertebra ; ' ttiei/ have no ossified pleurapopJiysesy Professor Owen's " pleurapophysis " is the rib or costal appendage of his typical vertebra. While he states, therefore, that the lumbar vertebra has no pleurapophysis, he means that it has no rib or costal piece. This over- sight (which, -with all respect, I believe it to be) has arisen from the evident error of mistaking the lumbar transverse jjrocess as being the counterpart or homologue of the dorsal transverse process, which, if such Avere the case, would leave the lumbar ver- tebra without a rib. vertebrae, then the elements (4) are as ribs seen in F,Jig. 444. Prop. IX. The sacral vertebrce develop costal appendages. — If it can be demonstrated that the first sacral vertebra is developed of nuclei equal in number, and identical in situa- tion, in form, and in mode of growth with those which are proper to lumbar vertebrae, then we may account both lumbar and sacral vertebrae as homologous with the costo-vertebral tho- racic form. And it does appear that the sa- cral vertebra {^,fg. 448.) is actually fashioned Fig. 448. of the same number of elements. For the serial order of nucleary deposition throughout the whole length of the spinal axis proves that the anterior nucleus (4) of the lateral mass (3, 4) of the sacral vertebra (b) is the true homologue of the so called " transverse pro- cess " (4) of the lumbar vertebra (B,fg. 447.), and of the costa (4) of the thoracic form (a, ^g.448.) and of the anterior half of the cervical transverse process (4, Jig. 445.), All these pieces hold serial order ; all are autogenous growths ; all are posited in the same relation with respect to the other vertebral pieces (1, 2, 3, 5) of the cervical, dorsal, and lumbar forms. Now, having once determined the proper identity of the anterior nucleus (4) of the lateral mass (3, 4) of the sacral vertebra (B,Jig. 448.), it becomes easy to recognise the homological cast and relation of all the other pieces of the sacral vertebra. The posterior half (3) of the lateral mass of the sacral ver- tebra (b) is the counterpart of the " tubercle " (3) of the lumbar vertebra (b,/'ct.447.), of the transverse process (3) of the dorsal vertebra (A,^g. 448.), and of the posterior half of the transverse process (3) of the cervical vertebra 445.). The spinous process (1), laminae (2, 2), centrum, or body (5) of the sacral vertebra (b. Jig. 448.) are evidently identical with the like-named parts of all the other vertebras correspondingly numbered. It will hence appear that sacral vertebrae do not differ from other vertebree ; and that it is an error as to the identity of the anterior nucleus SKELETON. 629 ^4) of the lateral mass of the sacral vertebra • (^,^g. 448.), which causes the human anatomist to name this anterior nucleary appendage as the *' peculiarity " of sacral form. This anterior nucleus of the sacral lateral mass, I call a rudimentary rib abutting against the iliac bone. Prop. X. The coccygeal vertehrce are de- prived of their costal apjiendages. — The serial order in which we find all spinal figures standing, renders it, under comparison, a de- monstrable fact, that the coccygeal bones (B,^g. 449.) are the debris or metamorphosed Fig. 449. remains of true and complete vertebrae, such as A of the thorax. It matters not as an ob- jection to the truth of this idea of coccygeal bones being the minus proportionals of full costo-vertebral quantities, that we now find them wanting many of those elemental pieces which are existing to these latter. For thongh it be true that it is impossible now to read the same number of elements in the last caudal ossicle (b) which we find elsewhere posited for all other vertebrae of the spinal series, yet I hold it to be also impossible for any ana- tomist to contemplate the presential character of a caudal bone and remain unproductive of the idea that the caudal bone (b), as a cen- trum (5), is a proportional left standing after the metamorphosis of all its other parts. If, then, we agree to this, we must also agree to the fact that those very parts (1, 2, 3, 4, of a) which a caudal centrum (such as b) wants, are identical with those same parts which are left standing to other vertebrae. Now, when I find that a coccygeal ossicle (b, 5) holds series with the centra (5) of all other vertebras, I have every reason to name it as being the centrum of its own vertebra, which has under- gone metamorphosis ; and therefore I may conclude that the plus original of the caudal ossicle (b, Jig. 449.) is equal to a, or to any other vertebra of the spinal series. It will be sufficient to the present argument, which holds comparison in order to establish the ideas of original or archetype uniformity, that we clearly understand how the original or archetype of a coccygeal bone is equal and uniform with any other vertebra of the spinal axis. The coccygeal bones (b) as nature pre- sents them to us are vertebral centra, having had subtracted from them their spinous ( 1), neural (2), and costal elements (4) ; and un- der this interpretation we nay have as strong an idea of the whole or plus quantity (a) of which caudal bones (b) have been metamor- phosed, as if we saw those quantities still per- sisting entire. The difference between any of the costo-vertebral spinal segments and a caudal bone is like the quantitative difference between a-\-bi\nda — b. Thus A,^g.449., minu.s the elements 1, 2, 3, 4, equals b ; while b plus the elements 1, 2, 3, 4, equals A. Prop. XI. 77ic first seven thoracic costo- vertebral figures are ivhole or phis qunntitics. — In no one respect do the first seven thoracic costo-vertebral figures (all equal lo fig. 4.50.) differ from each other; in each of them m;.y be counted the same elemental pieces ; and those pieces of each (marked as in fig. 450.) are identical or homologous both as to position, use, mode of growth, number, and linear order. These elements consequently bear the same name in each, and most properly, be- cause the corresponding pieces of each are absolutely similar. Consequently, also, tiie whole quantities (such as fig. 4i0.), which are Fig. 450. compounded of those pieces (1, 2, 3, 4, 5, 6, 7), should properly bear the same name ; and therefore I call them sterno-costo-verte- bral circles. There are, then, seven whole seg- ments (such as fig. 449.) of the human spinal axis, which absolutely resemble each other in quantity. These segments are posited in linear order, and by this arrangement they yield an absolute linear uniformity. Such linear uniformity is evidently the result of quantitatively equal figures being posited in serial order ; these figures enclose the thoracic space completely ; and, l)ecause they severally manifest an equal number of homologous ele- ments, so is it impossible to read any condi- tion of specific variation between them. As archetypes, or whole quantities, of the mam- mal spinal axis, these seven thoracic sterno- costo-vertebral figures have no special di- versity. When we compare them with one another we discover no more distinction between them than we find between the serial quantities + a-\-b, a-\-b. It is quite true, therefore, that there is at least one regional department of the mammalian spinal axis, to which we may apply the name of absolute uniformity, as fittingly as we might apply it to a linear series of circles. And it is, moreover, true that the thing called species is, so fiir as regards this linear series of plus thoracic figures, as perfectly absent, as if it were non- existent everywhere. But yet it is possible for nature to work specific variety from out of this linear series of thoracic archetypes (such as fig. 450.). And how may nature effect this ? Just in the same mode as she effects it in the creation of skeletal bodies comparatively contemplated, and this mode is the sub- 5 s 3 630 SKELETON. traction of quantity from whole or archetype originals. If nature arrested the develop- ment of, or, what amounts to the same result, if she subtracted different elemental parts from different regions of these se- veral thoracic costo-vertebral archetypes ; if she subtracted the spinous process (1) of one, the sternal element (6) of another, the rib (4) of another, or the spinous process, sternal piece, and ribs of another, then the remainders of those once uniform whole plus quantities would represent specific distinc- tiveness to each other. The remainders of the phis or whole quantities would then be the variable proportionals of such plus figures ; and, being proportionals, would therefore be proporiionally, that is to say specifically, various to them and to each other. Therefore I conclude that such species results not by the positing of new and unknown quantity, but by the annihilation or degradation of already known and posited quantity. In the plus figures (such as 450.) we therefore discern not only the already create and positive entity of uniform quantity, but even every condition of possible variety or species which can result by a subtraction of their elemental parts.* Prop. XII. The Jive asternal costo-verte- hral forms are proportionals metamorphosed * This whole or plus segment of the mammalian spinal axis, to which I give the simple name costo- vertebral quantity, may appear at first sight to be the same as the " typical vertebra" of Carus, Owen, and others ; but it is not so in fact, nor are the ideas which I entertain of the plus form, compared with other vertebrae of the same spine or different spinal axes, the same as theirs. I do not, for example, think it necessary to see in the tj'pical form so many elements and parts as those which Professor Owen names, in order to render it inclusive or archetypal of all varieties of vertebrae, which, in addition to the centrum, the neural arch and spine, and the costal haemal arch and spine, seem to produce such other elements as he calls zygapophysis, diapophysis, pa- rapophysis, distinct. If I can prove that the ventral costo-sternal pieces, under a process of metamor- phosis or degradation, suffer for the creation of such variety as we find ventrad of all vertebrae what- ever, then must it be evident that the simple costo- vertebral quantity, as I have drawn it, is all-suffi- cient as the archet}'pal whole composed (dorsad) of a neural arch and spine, and (ventrad) of a ha;mal arch and spine, together with their point of union — the vertebral centrum. If I can show that the lumbar " transverse process " and the anterior piece of the cervical transverse process (both of which are named " parapophysis " by Mr. Owen) are actually of costal growth, — the remains of the degraded plus ribs of a thorax, then there will be no need of them as distinct elements from ribs in my archetj-i^e or plus figure. Neither \n\\ it be required for my t}"pi- cal spinal figure that I should introduce into its proportions the parts called haemal arch and spine (the chevi'on bones) as things distinct from the ventral costal circles (the pleurapophyses),while I see good reason to believe the former to be the ribs them- selves somewhat degraded. In short, while I see it possible to interpret many of those elements which have been gathered together by the philosophic anatomist, as being necessary to the sixm of his ty- pical form, to be in i-eality but varjang propor- tionals of the same whole quantity, so shall I be enabled to divest my typical form of all needless complexity, and set up simplicity in its stead. from Jive steryial costo-vertehral plus quanti- ties.— The thoracic region of the human spinal axis consists for the most part of twelve costo-vertebral spinal segments. Seven of these enclosing space completely, arch for- ward and join at the sternal median line {Jig' 450. 6). Five of these (such as Jig. 451.) Fig. 451. do not enclose thoracic space completely, but fall short of this sternal median line (6) more or less (as at point 7,^g. 451.); and in this respect the five asternal costo-vertebral seg- ments are specifically distinct from the seven sterno-costo-vertebral plus forms. This dis- tinction or species is evidently owing to the subtraction of costo-sternal quantity (7 to 6) from the asternal five forms (such as Jig. 451.), which costo-sternal quantity is persistent for the seven sternal forms (such as Jig. 450.). The loss or subtraction of the sternal piece (from 7 to 6, 451.) becomes the advent or presence of the specific difference be- tween 450. and 451. ; and hence it be- comes clearly apparent that the law which exercises in creation of such difference be- tween the sternal and asternal spinal seg- ment is one of subtracting quantity from whole or plus forms, from which it is self- evident, that as the quantity of a sternal ele- ment and sternal costal pieces is that which is subtracted from the now asternal costo-verte- bral segment {Jig. 450.), so the original or plus quantity of this latter figure is of sternal costo-vertebral integrity or entirety, as I have drawn it in dotted outline for^o-. 451. Prop. XIII. The five lumbar vcrtehrcB are proportionals metamorphosed from Jive sternal costo-vertehral archetypes. — The se- ven sternal costo-vertebral circles are suc- ceeded by the five asternal costo-vertebral proportionals, and these latter by the five lumbar vertebrae. In this series of spinal segments it is easy to distinguish a descending scale of proportional quantities, whose only difference is one of quantity. This quanti- tative difference is exercised upon the costal elements only. In all other respects the lumbar and thoracic segments are similar ; for in both orders of structures we find the same elements, such as spinous processes, transverse processes (the tubercle being the transverse process of the lumbar vertebra), centra, and neural arches. In both w e also find the costal appendages, but these are not of equal growth or quantity. It is quite true, however, that the sternal costa is serially succeeded by the asternal costa, and this by SKELETON. 631 the lumbar " transverse process " or costa ; and this serial order clearly indicates that these are of the same original, but created specifically diverse by undergoing metamor phosis quantitatively. The originals, there- fore, of the lumbar vertebrae must have been such as the sternal costo-vertebral circles, and I have drawn this original quantity in dotted outUne for Jig. 452., for it is true Fig. 452. that the presential proportional condition of lumbar vertebrae, consisting of the elements 1, 2, 3, 4, ^,Jig. 452.), manifests no other variety or species to the archetypal quantity 1, 2, 3, 4, 5, 6, 7, elsewhere persisting, than a simple quantitative variety. Prop. XIV. The sacro-coccygeal series of vertehrce are proportionals degraded from ster - nal costo-vertebral circles. — That which is true of lumbar vertebrae, compared with thoracic segments, must be true of sacral vertebrae com- pared with the same. For as it seems that lumbar vertebrae are the proportionals of ster- nal costo-vertebral circles, so must sacral ver- tebrae, which are developed of elements iden- tical in all respects with those of lumbar ver- tebrae, be proportionals of the like whole quan- tities or originals. And this is what I affirm of both sacral and coccygeal spinal segments. Fis. 453. The last caudal bone, equal to the centrum (5, Jig. 453.), being a spinal centrum itself, is the vanishing point of the series. The next degree of subtraction is annihilation of all quantity proper to the costo-vertebral original whole quantity, the complement of which I have drawn as the parts marked 1, 2, 3, 4, 6 around 5, Jig. 452., thereby equating it with the plus thoracic form. Prop. XV. The seven cervical verttbrcB are proportionals degraded from seven sterno- costO'Vertehral whole quantities. — The same elemental quantity which is proper to a lumbar vertebra is to be found in a cervical vertebra. In both {y'xAiiJigs. 445. and 447.) we distinguish the centrum (5), the neural arch (2), the spinous (1), and transverse pro- cesses (3), and the costal ruditnents (4). In both we find that the difference which they manifest on comparison with the costo-ver- tebral thoracic archetypes is simply a differ- ence in costal quantity ; and hence the same reasons which have been here advanced for regarding the lumbar segments as propor- tionals of sterno-costo-vertebral circles, may be also applied as proof of the truth of the interpretation that cervical vertebrae (such as fig. 454. ), are also proportionals of the like Fig. 454. whole originals, and therefore* I have equated it with the thoracic whole quantity. Prop. XVI. The mammalian spinal axis consists of a series of segmental quantities, whose only variety or specific distinction depends upon proj)ortioning from whole thoracic quantities. — The truth of this proposition has been established by the foregoing remarks. All the spinal segments of those regions of Jig. 4^55., named cervical, thoracic, lumbar, sacral, and caudal, are not uniform, because they are not equal quantities. A cervical uniformity throughout the spinal axis would require that all the serial segments stood in cervical quantity. _A lumbar uniformity would require all the serial segments to be of lumbar quantity. The same with respect to sacral uniformity ; and the same of caudal uni- formity. A thoracic uniformity would also require the spinal axis to be of thoracic sterno-costo-vertebral quantity from cranium to the other extreme of the same linear series, such as is represented in Jig. 455., where the ribs are indicated in dotted out- line in the neck from 1 to 7, and in the loins from 20 to 24. In neither of these con- ditions is the mammal spinal axis developed; and therefore it is that the original plus uni- formity of all the segments from 1 to 25 is interrupted, the serial quantities being now developed of thoracic or plus, and of minus or cervical and lumbar, &c. proportions. Now as to the just interpretation of the natural law which creates this Jigure 455., thus com- posed of spinal segments in plus and minus variety, I apprehend that it is more rational to regard nature as being an artificer who, after creating a prime-model of whole or entire dimensions (such as Jig. 455.), with the ribs s g 4 632 SKELETON. and sterniira drawn at neck and loins, as well as thorax, degrades this prime-model to the dimensions of a specific or proportional variety, by obliterating costal quantity at Ficr. 455. neck and loins, than to understand her as having first given creation to an ens of lesser, proportions (such as Jig. -ioo.), with the cervical and lumbar vertebrae lesser than T7ie JIavimalian Skeletal Axis," Shovring in dotted outline at the neck and loins ttiose costo-sternal quantities which, if present, would render these regions equal to, and uniform with, the thorax. those of the thorax, and then varied all other forms to this ens by a superaddition of new and hitherto unknown elements. The former idea is that which I am endea- vouring to establish throughout these pro- positions. Original uniformity, or the prime model or archetype, \\z. Jig. 455., with the costo-sternal quantities at neck and loins, is that figure whose proportions I mean to develop by my mode of comparison ; and the idea that the degradation or subtraction of parts proper to this archetype is that law which becomes the creator of specific variety. When I find that the osseous quantity of a caudal centrum, a sacral, a lumbar, or a cervical vertebral quantity can severally be referred to the like quantities contained in a sternal thoracic costo-vertebral segment*, I entertain the opinion that the latter, as a whole or prime model, has undergone meta- morphosis to the creation of such propor- tional variety as the former instance ; and this opinion, I fancy, is more consonant with reason, or is, at least, more pliable for un- derstanding, than to suppose that nature, after having first given creation to the caudal, lumbar, or cervical S'^gments of the spinal axis, created, as it were b}^ after thought, other figures secondar}- and special to such as * Every' lesser unit of the vertebral chain finds its quantitative homologue in a part of the greater unit, and all lesser units in the greatest unit, which I therefore name as the archetype. In the following beautiful sentence, Carus expresses his idea of the organic whole quantity compared with the lesser thing or species : — " La partie d'un tout organique est incontestablement douee d'un organisation d'au- tant plus e'leve'e qu'elle repe'te plus parfaitement en elle I'ide'e du tout, et le tout lui-meme est d'autant plus parfait qu'il correspond d'avautage a I'ide'e de la nature entiere dont nous devons reconnaitre que I'essence est Funite des lois eternelles revelees dans I'infinie diversite de la manifestation." See C. G. Carus,Traite Element. d'AnatomieComp. c. xi. p. 26., traduit par J. L. Jourdan ; see also Carus, You den Urtheilen des ELnochen und Schaleugeriistes, fol. Leipzic, 1828. these by the addition of new and unknown elemental structure, such as a thoracic rib and a sternal piece ; for in the absence or presence of certain elements consists all the specific difference between all segments and regions of the mammalian spinal axis. Prop. XVIL Uniformity of structure is a conditio7i proper to the plus thoracic 07-igi- nals of the spinal axis of the mammalian body. — It is a demonstrable fact, that all the spinal segments of those regions (^Jig. 455.), named cervical, lumbar, and sacral, differ trom the first seven thoracic costo-vertebral circles (those numbered from 8 to 14) by quantity only ; and this quantity is costo-sternal. It is also demonstrable, that the coccygeal seg- ments of the spinal region, represented by the centrum (o,Jig. 453.), differ from the same whole forms by quantity only : this quantity is the neural arch and spinous process, in addition to costo-sternal elements, all of which I have drawn in dotted outline around the caudal centrum (d, Jjg. 453.). Now this differential condition, visible between all such spinal segments, being one of quantity only, it must appear evident that the idea of a structural uniformity can alone be established, first by interpreting the present condition of cervical, lumbar, sacral, and caudal segments, lis being one of proportional variety ; and second, by comparing them as such with their originals, which I assert to be of sternal costo- vertebral quantity. If, then, the original or archetypal quantity of a caudal, a sacral, a lumbar, or a cervical segment be a sternal costo-vertebral segment, it will follow that the series of such originals constitutes plus uniformity, as indicated in Jg. 455., whose serial units at neck and loins are equated with the thoracic units, whereas the series of such segments as cervical, lumbar, sacral, and caudal quantity constitutes proportional va- riety or specific difference, created out of the substance of the uniform archetype costo- vertebral originals. In order to fix the idea SKELETON. 633 of uniformity throughout the serial line of spinal segments such as they are, we must submit them to a mental process of com- parison which is to tell us what they once were. For as it is evident that these seg- ments are only proportionally various, so is it equally evident that their plus originals must be uniform and absolutely similar. When I compare a caudal, a lumbar, or a cervical segment with a sternal costo- vertebral seg- ment, I must acknowledge to a specific dif- ference existing between these bodies ; but then I also have every reason to believe that this specific difference is only a proportional difference.* If, then, the cervical, lumbar, or caudal segment shall severally prove to be parts or proportionals when they are com- pared with a sternal costo-vertebral segment standing at the thorax, it cannot be errone- ous to read them as having been meta- morphosed from Vieir oiun originnln, such as those of tha thorax^ and hence 1 conclude that uniformity alone characterises the series of such originals. f Prof. XVIII. Every spinal segvient irhich is lesser, refers to every spinal segment ivliich is greater ; and all lesser segments refer to that ivhich is greatest. — If it be easy to conceive that the last caudal bone (i,J%.+44'.) is a lesser quan- tity metamorphosed from such another quantity as the penultimate caudal bone (ii, fig. 444.), where can be the difficulty in rationally inter- preting both to be as quantities metamor- phosed or proportioned from such quantities as lumbar vertebrge (e, fig. 444.), and hence from such segmental quantities as sternal costo-vertebral plus forms (such as fig. 453.). I could not entertain this idea of a caudal bone, if I found that it were an ens holding within its dimensions any elemental part which may not also be found to be contained in the plus form of fig. 450. ; or if it were not the fiict that the archetype (fig. 450. or 453.) could undergo a simple graduated metamorphosis of its parts (1,2, 3, 4, 6), so as to simulate any other segment of the spinal axis lesser than itself J A caudal ossicle, * The number of proportionals capable of being struck from a whole quantity being of infinite amount, it -will be also seen that the number of species wliicli those proportionals themselves i-epre- sent are likewise infinite. " Species autem ilia ab- scissio infinite recte vocari possit." Bacon, Nov. Organon Scientiarum, Aph. 26. t The series of the archetypal sterno-costo-verte- bral circles constitutes absolute uniformity ;and when w^e contrast with this quantitative uniform line this other line of graduated proportional serial quantities, such as the present state of the mammal skeletal axis exhibits them, Ave are enabled to estimate the law which has created the line of proportional quan- tities such as we find it. When the special or pro- portional thing is contrasted with the uniform Avhole or complete quantity, the contrast gives the inter- pretation. If species arise from the infinite sub- division of the line of Avhole quantities, then this latter, as perfect quantitative uniformity, may be defined as follows : — " Unitas (uniformitas) est sine commissura (sine hiatu) continuatio." Seneca, Na- tur. Qua}st. lib. xi. X " The great advantage of this idea of a whole is, that a greater quantity of truth maybe said to be such as the centrum (fig. 453. 5), reminds me as strongly of its original whole quantity, viz. fig. 453., from which it has been meta- morphosed as a dorsal spinous process (I, fig. 450.), separated from that thoracic seg- ment, reminds me of the whole of such seg- ment. If it be true that I could never thus interpret the caudal ossicle, if I had not seen the thoracic archetype, this can be no argu- ment to show the error of my interpretation ; for it is equally true, that I could never know of what whole figure the dorsal spinous pro- cess was a part, if I had not seen the thoracic segment named costo-vertebral.* Prop. XIX. Structural uniformity cannot characterise such spinal segments as are pro- portionally or quantitatively various. — A cer- vical segment differs from a thoracic seg- ment by existing quantity ; and the like dif- ference prevails between all other segments of the spinal series, therefore those segments cannot be termed uniform. But though these segments are not uniform by reason of their being unequal things, still it is most true, that they are only diversified by reason of their quantitative inequality. In fig. 455. all the spinal segments are rendered plus and equal, by supplying in idea the osseous quantities lost at neck and loins. Prop. XX. Specific variety is none other than proportional variety. — A cervical, a lum- bar, a sacral, or a caudal spinal segment is various to a thoracic segment, forasmuch only as the former fall short of those parts which are proper to the latter figure, and therefore I say that specific variety is none other than proportional difference. iFor when, as in fig. 455 , w^e equate those segments which are proportionally difllerent, we re-establish uniform series. Prop. XXI. The Jcnoivledge of the differ- ential quantity between all spinal segments renders them exactly uniform in idea. — Upon holding comparison between one spinal seg- ment and another, when I find that certain persistent parts of the segment of greater dimensions, viz. that of the thorax (fig. 455.), are those which are subtracted from the segment of lesser dimensions, viz. that of the neck or loins (fig. 455.), this is tantamount to the knowledge that the lesser segment has lost those parts which are persistent for the greater. And therefore I say, that in the knowledge of those parts which are wanting contained and expressed in it." Sir Joshua Rey- nolds' Discourses, Discourse xi. * The self-evident truth which attends the geo- metrical axiom, that tlie whole is greater than its parts, needs no comment to sustain it ; but that the part stancbng alone per se still refers to the whole quan- tity of which it is the part, requires to be insisted iipon much oftener, for at first sight Ave are apt, Avithout reflection, to regard it as it is in the light of a perfect figure. Hoav many anatomists are there A\-ho neA'er Avaken to the idea, that CA-ery lesser seg- ment of the spinal axis refers to the greater Avhole quantity; and yet in this interpretation the Liav of formation enshrines itself. "L'ensemble de tons les ordres de perfections relatiA-es, compose la perfec- tion absolue de ce tout." Bonnet, Coutemp. de la Nature, part i. chap. iii. ^34 SKELETON. to the lesser, I may idealise it by a mode of equation to uniformity with the greater. For while I find reasons to believe that the spinal segment {fig. 454.), which is now in cervical form as consisting of the parts 1, 2, 3, 4, 5, has lost its sternal piece (6) and most part of its lateral costae or ribs (7), then I have only to supply in idea the sternal piece and costse to the cervical vertebra, in order to equate this segment to the thoracic plus character of fig. 450. The same mode of comparison carried out through all the serial segments of the spinal axis, will likewise render them in idea all equal to thoracic costo- vertebral arche- types, as seen in fig. 455. ; and this is the mode of comparison by which alone the ana- tomist can understand the law of skeletal formation. Prop. XXII. Without knoiving the full di- mensions ofivhole or uniform quantities, ive can never rightly understand the real character of lesser and special forms, and therefore can never otherwise understand the law of formation. — The object of the present mode of com. parison is, to ascertain the exact forms of whole quantities or archetypes, and the means adopted to this end is the synthetic mode. This object, and the comparative method by which I here endeavour to prove the existence of it, differs from all other methods hitherto adopted by comparative anatomists in search of the true interpreta- tion of skeletal fabrics and the law of unity in variety. 1 mean to show that anatomical science can never know the figure of skeletal unity or uniformity until it shall know the archetype or prime model of complete dimen- sions from which all skeletal fabrics are fashioned ; and, furthermore, that it can never comprehend the source of variety or specific difference until it shall interpret this as attaching to variable figures of osseous quantity degraded from the archetypes, and hence that it can never understand the law of skeletal formation in any other light ration- ally, unless in the sense of a law of degrada- tion from whole or archetype skeletal fabrics. Now it appears to me, that by means of the mode of comparison which I here make use of for ascertaining the whole original or archetype quantity from which such a fabric as the mammal spinal axis {fig. 455.) is fashioned, we may also define as clearly the originals or archetypes of a large number of s[)inal axes throughout the classes of mammals, birds, reptiles, &:c. ; for, no doubt, what is true of one form must be likewise true of plural numbers of forms, such as skeletons which manifestl}' bear a remarkable analogy the one to the other. The same law of de- gradation by which a cervical, a lumbar, a sacral, and a caudal ossicle happens in the mammal spinal axis, appears to me to give a complete solution of the more extended problem, viz. how it happens that animal spines of all classes present differences in the cervix, the thorax, the loins, the sacrum, and the caudex. For while I find, by compara- tive reasoning held upon the serial segments of the one mammal spine, that a cervical or lumbar, &c. segment has actually lost costo- sternal quantity, and that by this loss it now differs from a thoracic costo-vertebral arche- type, it must follow that the original or whole archetype quantity of a cervical or lumbar spinal segment is the equal of a thoracic costo-vertebral segment ; and the very same reasoning lends a true interpretation to all cervical, or lumbar, or sacral, or caudal seg- ments wherever they appear, whether in the class mammalia, birds, reptiles, g. 468. TTie cervical spine of the Ornithorhynchus, Showing that h the coracoid bone, d the clavicle, and e the sternal end of the rib, are serial homo- lognes. we not regard the pieces 1,2,3.4,5, con- tinued serially into the rib of 6, as beins cos- tiform like^vise, despite the fact that anato- mists have already regarded the pieces 1 and 2 as the coracoid and cla^acular bones r Do we not see in fig. 469. that the parts 1, 2, 3, 4, 5 point to the parts a, by c, rf, e, just as the part 6 points to the part/'? If it be said that the parts 1 and 2 (the coracoid and clavicle), being disconnected from the cervical ribs (a and b) are therefore to be regarded as quantities unrelated originally to a, b, I must doubt whether this can efface from the rational mind the belief that the now separated pieces o, 1 or b, 2, taken as whole quantities, equal the costo- sternal form /, 6. Whether or not the above-mentioned interpretation as to the origin of the bones called clavicle and coracoid be true, must be seen through the facts as they are here recorded : but be this interpretation as it may, I plainly affirm that the comparative anatomist has no positive evidence, near or remote, directly or indirectly, either by a similarity of structure, or function, or po- sition, or auiiht else, to resard the cora- Fis. 469. T7i€ cervical spine o f a Lizard. In which the cervical ribs, a, b, c, d, e, point to the coracoid bone 1, the clavicle 2, and the pieces marked 3, 4, 5, as their proper continuations, and j ust as the sternal rib, 6, continues the vertebral rib, /, to the sternal median line. coid process of the human scapula as the counterpart of the bone (d fig. 466.) called coracoid in the bird, or of 2. the coracoid of fig. 469., the reptile.* The anatomist may just as well call the sternum a series of vertebrae (a statement by-the-by which some * On referring to the " Homologies of the Verte- brate Skeleton," I find, in the section " General Homology-," the following opinion, advanced re- specting the coracoid bone, that it " is always deve- loped from an independent osseous centre (a rudi- mental representative of the hsemapophysis), which coalesces with the pleurapophysis in mammalia, and only attains its normal proportions completing the arch with the haemal spine (epistemum) in the monotremes." The reader will not, perhaps, com- prehend the author's meaning in this sentence, taken separate from the flowing context of the work cited. The meaning of the sentence is this : — The scapularv- organ is referred to the occipital vertebra, as the hjemal arch of this segment of the skull, the scapula is interpreted as its pleurapophysis or rib, and the coracoid bone (process) is accoxmted the haemapophysis appended to the costiform scapula, and thus the t^-pical occipital vertebra is formed. Although I regard the work from which I have quoted to be a lasting monument of learning, re- search, and inductive reasoning — a worthy effort in a great cause — still I cannot concur in the opinion which that work announces respecring the relation between the scapulary member and the occipital vertebra. have made)*, as to say that there is identity between the human coracoid process and the bird's coracoid bone. However endless may be the whole account of specific difference be- tween bone and bone, and between one skele- tal form and another, st:ll there does appear happily some well-marked limits to the homo- logies. Xo one, for example, wiil torture the bone named scapula into an identity of cast w ith the bone named rib t ; and I believe that the same absolute difference is possible to be pointed out between the coracoid process of the human scapula and the bone named cora- coid in the bird, or that bone so named in the chelonian reptile. The coracoid process of the human scapula is an elemental part proper to the scapula, just as the centrum is a part proper to the vertebra The bone called coracoid (d, fig. 466.) in the bird abuts against that part of the bird's scapula where the coracoid process usually appears in mammal scapulae ; but this coracoid bone is not representative of the mammal coracoid * De Blainville, Meckel, and Carus entertain this opinion, which certainly has no support from, natural evidence. + It is true, however, that this very opinion re- specting the scapula is advanced by the distin- guished author of the " Homologies," &c. SKELETON. 6^7 process produced to sternal junction ; and I shall hereafter prove that the coracoid process of the mammal scapula is as distinct a piece from the coracoid bone of the bird, as the centrum of a vertebra is from the costa. In order to understand aright the law of formation, it is as necessary to know what parts are identical and different in two or more skeletons, as it is to know what parts are identical and different in two or more verte- brae ; an error in the one or in the other is fatal to a proper understanding of the law which governs the development of both. While we view the clavicle {b,fg. 470.) in connection with the cervical rib behind («), we then find that the entire of Jig. 470. repre- sents a quantity equal to the thoracic arche- type, inclosing a visceral or haemal space ven- trad, and a neural space dorsad. This same whole quantity of the archetype is also seen in Jig. 471., where {b) the furculum joins c, the sternum, and points dorsad to a, the cervical Fig. 470. The cervical vertebra, with the rib, a, the clavicles, b, and first sternal piece, c, of the crocodile, form- ing, in their connected totality, the sterno-costo- vertebral whole quantity. rib of the cervical vertebra. In like manner Jig. 472. shows the dimensions of a thoracic Fig. 471. The cervical vertebra, with its rib a, pointing to the furcular bone h, and the sternal junction c, which parts in their totality form the stemo-costo-ver- tebral quantity in the albatross. whole quantity when we take (a) the cervical rib with {b) the coracoid bone (so called in tiie bird) and joining (c) the first sternal piece. Fig. 472. The cervical vertebra, with the rib a, the cora- coids h, and the first sternal piece c of the albatross, forming the whole quantity. When the whole quantities of the sterno- costo-vertebral circles suffer a dismemberment of their integral [)arts, then it is that special or diversified objects first appear — then it is that clavicles become special to coracoid bones, and both to ribs — then it is that the anatomists pursue, with special distinctions, fragmental plurality, and lose sight of the intelligible form of unity on the whole. Osteogenic is constant to the law of serial order. As rib follows rib in serial order — a cir- cumstance which indicates the homological cast of both — so rib, and coracoid, and clavicle, which take serial order, indicate by this same fact their own identity or homological relation. But the mammal's coracoid process is a part distinct from the bird's costiform coracoid bone. The former never takes place of the latter, but is a part proper to the scapula alone.* * Professor Owen's idea of the relationship of the mammal scapulary member and its coracoid element to the occipital vertebra, must imply that the cora- coid clavicle of the bird is (if the mammal coracoid pi'ocess and the bird's coracoid bone be considered by him to be homologous parts) also referable to the occipital vertebra. This homological relation, I am bound to say, I could never discover; and if the asserted relationship between these parts shall be ever received as an opinion true to nature, the learned author is certainly the discoverer. For my own part, hoAvever, I must confess myself no convert to the belief that so large an amount of displace- ment between any two numbers of a whole quantity, such as that which, according to the author, is instanced in the totality of the occipital vertebra, taken with the scapulary limb, ever occurs, but I am rather impressed vnth. the opinion which the im- mortal Goethe advanced respecting the fixity of place which osseous pieces of the endo-skeleton in- variably hold : " L'oste'oge'nie est constante, en ce qu'une meme os est toujours a la meme place." CEuv. d'Hist. Nat. p. 41. I T 4 648 SKELETON. While clavicles, coracoid bones, and ribs appear identical, we then can readily under- stand liovv a bird or re[)tile may possess two or more clavicles, according as the laws of form shall subject two or more of the original costae to clavicular modification. The cla- vicles, therefore, of the mammal and the cla- vicles and coracoids of the bird or reptile being costal quantities under metamorphosis, these bodies are to be regarded as the ribs proper to those cervical vertebrae, opposite to which they af)pear in all skeletal forms.* Prop. XXXV. Marsupial bones, pubic and ischiadic bones, and ribs, are identical parts of the costo-vertebral luhole quantities or archetypes. — Wherever we find these parts, viz. sternum, rib, and vertei)ral piece, occurring in skeletal fabrics, we shall never find that they take the place of each other. The sternum, even when appearing isolated from the other parts, is still holding its proper locality at the median line in front. The rib is always found laterally, and the vertebral piece always behind. The sternal pieces hold serial order, and hence we know them throughout all variety of modifi- cation. The costae in like manner hold serial order, and hence we also recognise these parts. The vertebral pieces hold their own serial order, and thus we know them. The costal, the sternal, and the vertebral serial orders are never interrupted by the introduction of a new and unknown element among the bodies which form each serial line. There never occurs among the vertebral pieces behind any other thing which by being diffbrm to vertebrae, may disconnect that vertebral series. The same remarks apply to the sternal bodies in ii'ont, and the same to the costal pieces ar- ranged laterally. Every body which holds serial order with the sternal bone is a sternal bone, and constituting sternal serial order. Every body which holds serial order with a vertebral bone is a vertebral bone, and consti- tuting vertebral order. Every body, also, which takes serial order with a rib is a rib, and constitutes costal-serial order. Every body, therefore, which on first sight shall seem to be specifically distinct from that order with which it holds series, is in fact only rendered special in such order by modification ; origin- allv it is identical with all the pieces of that same order. Just as the clavicle and coracoid bone hold series with ribs, and are ribs originally, but rendered special by modification, so does it appear that the marsupial, the pubic, and is- chiadic bones, which hold serial order with ribs are ribs originally, but now presenting in such conditions of modification as we mark by * The same reasoning which leads the author of the " Homologies" to refer the coraco-scapular arch to the occipital vertebra, induces him to pronounce the mammal clavicle to be naturally related to the atlas vertebra. Now, I cannot understand why the author's views, which are certainly correct, in so far as he is led to believe the pair of clavicles to be the inferior arch of some one of the cer\ncal vertebrre, should make choice of the atlas so remote, in prefer- ence to that cervical vertebra, opposite which the clavicles appear. nomenclateric difference. A clavicle, a cora coid bone, a marsupial bone, a pubic bone, and an ischiadic bone, are thus differently named in order to point to their several sj^ecialitits of caste. But through these special characters their costiform original character is still visible, and therefore I call them ribs modified. These modifications which clavicles, coracoids, mar- supial, pubic, and ischiadic bones present, when contrasted with each other and with rihs, are in reality of no greater amount than those varieties which are apparent among those bodies which we name ribs, enduring as such through the skeletal axis. At the present day we well know that the thing named rib is not necessarily confined to that region of the skeletal axis named thorax. Ribs are found embracing the ventral region of fishes, and all spinal regions of ophidians. Ribs of unequi- vocal character are also developed embracing the venter of Saurians. Ribs are jutting out laterally from the loins of the draco volans, supporting the parachute of that animal. In fact we can readily distinguish the costal cha- racter of many bones, even though they are separated from their proper vertebral centres behind. See these osseous quantities, which project from the sternal bone behind, ensheath- ing the venter of the bird's, and the Saurian's skeleton, and standing free from the lumbar vertebral pieces, to which, nevertheless, they refer, — are they not ribs, which special laws have dissevered from the spinal axis behind ? It is not, therefore, necessary to the bone named costa, that it should always hold at- tached to the vertebral form posteriorly, and to the sternal form anteriorly. And why, therefore, not extend the name costa to those Fig. 473. c osseous parts which do not present greater varieties compared to ribs, than ribs do when compared to each other. The law of serial SKELETON. 649 order must indicate the true character of those osseous parts, whose various names serve to blind us to the actuality of their homologous caste. Examine closely the anatomical fact, and see whether I am stretching the imagina- tive faculty while I assert that the pubic (5,7) and ischiadic bones (6, 8) of the bird {Jig. 473. ostrich) are actually springing from the lumbar vertebrae like true ribs, (1. of the thorax). If, therefore, it be the rule to affirm as incontest- ible truth that these pubic and ischiadic bones of the bird are counterparts of the bones so named in the mammal, wherefore should we stop here, and hesitate to name both orders of bones (those of the mammal as well as of the bird) as ribs originally ? Even up to the present hour we find the osteologist strolling the Museum, and still marvelling at the interrogative marsupial bone (Joy jig. 474.). What is it ? Whence is Fig. 474. (4), hold series with the marsupial bone (6) , just as this latter holds series with the ribs (7, 8.) Does not this serial order prove the identity of all these bodies in common ? Do they not all alike abut against their sym- metrical fellows at the common median line ? Does not the pubic bone exactly correspond with the sternal median line ? In ^g. 475., representing the continuous series of costiform bodies from the clavicles Fig. 475. Tlie thoracic and ventral median line of the Orni- thorhynchus, Showing the serial homology between the coracoid bones (2), clavicles (1), ribs (3), and the marsu- pial (6) and pubic bones (5). it ? What is its interpretation ? What else, I answer, can it be, but a ventral rib, proper to some one of the lumbar vertebrae behind. If in these pages I have furnished the querist with the idea that a lumbar vertebra has lost costo-sternal quantity, then he cannot be un- productive of the idea, that this marsupial bone, which now occupies the place of this costal quantity of the lumbar vertebra, is none other than this quantity itself. Besides this, it is also evident, from the serial order which the marsupial bone (6,/a. 474.) holds with the line ol costae (3, 8, 7), that it is itself costiform. Now, in Jig. 474., it will be also seen that the pubic bone (5), and the ischiadic bone The thoracic and ventral median line of the Crocodile {dorsal aspect^, Showing the same serial order of the parts named infg. 474. (1) to the ischiadic bones (4), it is scarcely possible to recognise a difference between all forms of this serial order. The clavicles (1) are succeeded by the ribs (2, 3, 8), these by the ventral ribs from (8 to 6), and these by the piibic bone (5), and the ischiadic bone (4). The homology between the bodies, (1) the clavicle, and (2) the rib, is as clearly ap- parent as between (5) the pubic bone, and (4) the ischiadic bone. Moreover, the homo- logy between (1 and 2), (5 and 4), is as clearly apparent as between any two ribs of the series. If {b) the pubic bone still held its original place at (7), and had not discon- nected itself from the ischiadic bone (4), it 650 SKELETON. would not be more like the clavicle (1) than it is in its present situation. In ^or. 476., the pubic bone (2) occurs op- posite to the sacral vertebral rib (1), and the Fig. 476. Tlie sacral vertebrce and pitbic forms of the Crocodiles forming the whole quantity. whole form is thereby com{)leted as the sterno- costo-vertebral-archetypal quantity. The part 2, of ^g. 476., may, therefore, as appro- priately be termed a pubic rib as a costiform pubis. This pubic bone {2, Jig. 476.) is sepa- rated from the sacral rib by an interval equal to the iliac bone, and this latter is regarded by a high authority * to be of costiform cha- racter ; but in the present reading I have no need to view the bone in this regard. Prop. XXXVI. Chevron bones and ribs are identical parts of the costo-vertebral ivhole quan- tities or archetypes. — As every part which shall appear plus upon a cervical or lumbar vertelM'a, such as cervical or lumbar ribs, may be referred to the original whole quantities from which the cervical or lumbar vertebrae have been metamorphosed, and gain their proper interpretation accordingly, so may those parts which now and then appear plus upon the caudal vertebras, such as " chevron bones" (4, of fig. 477.), be likewise referred to the original whole quantities from which those caudal vertebras have been degraded. We have seen reason to interpret the caudal bone as the centrum of the vertebra, — of which vertebra ? Of the thoracic plus vertebra ; for why not of this plus archetypal form, as well as of any other form less in quantity than this archetype? If the caudal bone be considered as a part degraded from the equal of the ium- * The author of the " Homologies " entertains the opinion that the iliac bones are the " pleurapo- physeal" (costal) elements of the sacral vertebra, and thereby he connects the pubic arches (his hte- mapophyses) with their proper vertebral pieces in the sacrum. This opinion as to the costiform cha- racter of the ilium or haunch bone, is by no means that Avhich I hold respecting it, nor can I believe that any other anatomist will discover the similitude between an iliac bone and a rib, any more than be- tween a scapula and a rib, or any more than they will find to exist between a sternal piece and a spinal vertebral form, even though the imposing names of Oken, Meckel, and De Blainville intro- duce this latter opinion. bar vertebra, why not also from the equal of the thoracic costo-vertebral archetype ? If the caudal bone gives evidence of the fact that its present condition is owing to the loss of the Fig. 477. The caudal vertebra of the Dugong, Showing that it is not the typical or whole vertebral quantity. neural arch, the spinous process, and trans- verse-costal processes, and if it elicits accord- ingly the interpretation that had those ele- mental quantities still persisted, that which is now the caudal would have been equal to the lumbar vertebra ; so, on the like grounds, we may elevate ourselves to the reading, that if the thoracic ribs and ster- num, the neural arch and spine still per- sisted, that which is now the caudal bone would have been equal to the thoracic arche- type. Such a reading I here venture to put forth respecting the caudal bones {fig. 477.), and when these develope the chevron os- sicles (4), I interpret them as being proximal parts of the costal arch (1, 2, 3), left standing after the degradation of the whole archetypal quantities. If a thoracic costo-vertebral archetype, such as fig. 478., whose costal Fig. 478. Tlie caudal vertebra of the Dugong, Showing how the costal quantities are metamor- phosed into the chevron bones. arch is 1, 2, 3, undergoes such an amount of degradation as to sternal and costal quantity, that the proximal or vertebral ends (2) of the ribs (2, 3) alone remain persistent ; and if these ends (2, 3) of the ribs, while remaining still articularly appended to the vertebrae, are bent towards each other and to the median line, taking the place of the parts 4, 5, then SKELETON. 651 we shall have produced such a vertebra as Jig. ¥11. or 478., which, composed of the ele- ments 1, 4, 5, happens in the tail of" cetaceans, saurians, fishes, and many species of even the quadruped mammalia. There are chevron os- sicles developed on the caudal vertebrae of the quadrumanous species. The caudal vertebra {Jig. 477.) having the chevron bones (4) and inferior spinous process (5) appended to it, is taken to be the typical vertebra by all ana- tomists. They regard it as containing all the elemental parts proper to all vertebrae, an opinion, the error of which I shall not here stay to point out, if it be not already demonstrated by what 1 have elsewhere spoken. Taken as quantities of osseous form, it would be as impossible to distinguish the same parts in such a " typical " vertebra, as either 9, 10, or i\. Jig. 479., and that which stands at the thoracic region of spinal series, as it would be to read the quantity a — b and a-\-b as equal. In Jig. 479., which represents the cetacean loins, it will be seen that the thoracic ribs 1, 2, .3, hold serial order Fis. 479. Tlie lumbar region of Showing a serial degradation of with the costiform pubic arch 7, and that this series is continued into the lesser quantities of chevron bones 9, 10, 11. This serial order indicates the homology of these several struc- tures. Prop. XXXVII. The sternal median line ranges from the maxilla to the pubic bones of the abstract archetyjml skeletal fabric. — In order to comprehend the truth of this propo- sition, the reader will have to exercise his mental as well as his bodily vision. He will have to expand l.is view over a large number of facts, and to compare these one with another, and sum together all the evidences, making them demonstrate the generaUzation which I here propose to establish. The ab- stract idea which general comparison has fur- nished me with respecting the sternal median series of osseous pieces, I shall endeavour to develope in the reader's mind, after the same manner in which it was furnished to my own ; and comparison of anatomical facts shall be my instrument. When I compare all skeletal fabrics by the sternal apparatus, I find that such an infinite variety marks them in respect to this par- ticular, that it would take a long and busy lifetime to make a record of one half of those varieties ; and, after all, it is most true, that such record would not be worth one jot to science, since it would leave us in the end no better informed as to the law producing this variety, than when we first began. The one great fact which I shall remark upon in reference to the sternal apparatus is, the Dugong^s skeleton, the ribs into the chevron bones. that it is a part which varies not only in several species but even in the one species, and that it is a structure the most indeter- minate and indefinable of all those consti- tuting the osseous skeleton. It is produced of variable lengths in the human body, and in every other animal species regarded per se. Now, assuming that the interpretation of sternal variety, and not the enumeration of it, is the sovereign and paramount object of com- parative research, I here venture to affirm, that there is no other mode of accounting for this variety, as it appears already created, or of interpreting the process which has yielded it, excepting that of regarding every variety of sternal apparatus as being propor- tional lengths cut from a whole linear sternal quantity, drawn in continuous order through the median line of the fore aspect of the animal fabric from end to end. The reasons which lead me to adopt this reading of the source of sternal variety are as follow. When I examine the human skeleton as a form isolated from all other forms of the four higher classes of animals, I find the sternal series of osseous pieces extending through that region of the median line in front where the fully produced ribs meet it and enclose thoracic space completely. This costo-sternal junction happens generally between the seven first ribs and the sternal apparatus. It is owing to this sternal union of these seven ribs, that the human anatomist terms them " true ribs." The five succeeding costal pairs he terms " false ribs," because they are 652 SKELETON. asternal, that is to say, falling short of sternal junction. A comparison held between these seven sternal and five asternal ribs, must lead the reason to draw the conclusion that the difference between both orders of these ribs is caused by the subtraction of a certain osseous quantity from tlie asternal ribs, which circumstance has dissevered them from the sternal median line ; and hence follows the relationary inference, that if this osseous quan- tity had not suffered subtraction or meta- morphosis from those ribs which are now in asternal character, these would have per- sisted in their original archetypal or plus quantities, and would thereby have joined a sternal median line, just in the same way as the seven true ribs still do. In this cise, we should have had twelve true or sternal ribs forming the human thoracic cavity. In the same way, again, I may remark, that if the five ribs which are now lost to the lumbar vertebrae, and which loss has rendered these bodies in the lumbar fashion, had still per- sisted in their original archetypal proportions, these ribs would also have joined a sternal median line, and would have thereby com- pletely enclosed ventral space. In such case we should have had seventeen true or sternal ribs. Again, if the original or archetypal costo-vertebral osseous quantities, from which the sacro-caudal series of vertebrae have been metamorphosed, had still persisted, these also should have joined a sternal median line, and completely enclosed space. In this case we should have had twenty-eight true or sternal ribs. And if the original archetypal osseous quantities, from which the seven cervical ver- tebrae have been metamorphosed, had also still persisted, we should then have had thirty- five true or sternal ribs. In which case the human skeletal axis, instead of numbering, as it does, thirty-five spinal segments of variable proportions, such as those of cervix, thorax, loins, sacrum, and caudex, would have pre- sented to us, in its original or archetypal quan- tity, the number of thirty-five sternal costo- vertebral spinal segments. In such a form, I imagine that the sternal median line would range from one extremity to the other of the serial spinal axis. And now let us examine, w hether this ideal archetype coincides with all natural evidence derivable from general com- parison. Not only does a numerical variation occur in human species as to the true or sternal ribs (for I have seen them counting from 7 to 10), but I will venture to predict, that we should find this numerical variation, as to sternal ribs, happening amongst the indi- viduals of any other species of the four classes, if we dissected them as frequently, and with as much interest, as we do the human body. In the human skeletal form, we are accustomed to name the seven sternal ribs as normal to this type ; and all excess of costo-sternal union as abnormal or anomalous. The like variation, from normal to abnormal, occurs amongst the individuals of every known species of skeleton ; and the reason which I assign for this variety of infinite account is, that all such variety, whether normal or ab- normal, is but a minus condition, degraded from a plus or archetype condition of skeletal form, which latter has all the vertebral pieces holding homologous series behind, all the costal pieces holding homologous series late- rally, and all the sternal pieces holding their own order anteriorly. In such an archetypal skeleton there could be no such hiatuses or gaps, in series, as those of the cervix and the venter, &c., where, be it remembered, all variety and " anomalous" creation occurs. Now is there not every good reason to be- lieve that the contrast, which the normal con- dition of any one species bears to the abnormal condition of that same species in respect to the number of ribs meeting at a sternal median line, is only a part of that general contrastive condition which all species bear to one ano- ther, in respect to this same costo-sternal union or non-union? Let us examine this truly marvellous law, whereby all contrasts of formation result, not only for the one spe- cies, but for all species : for it is this law which I conceive to be the proper aim of the osteologist. Let us not weary patience with recounting the facts that skeletal forms do differ, but let us rather furnish imagination with the one over- arching fact, as to how they are differenced, each one to each, and all to archetypal uniformity. All individuals of one species will, when viewed collectively, manifest the normal and abnormal contrasts to that same species, in respect to variation in the number of sternal, and the number of asternal ribs. All species, viewed collectively, will manifest the same, only in a greater degree, and in broader con- trast. When I compare the normal and the abnormal conditions of costo-sternal union in individuals of the same species, and also the numerical variety as to the number of sternal and asternal ribs, I find that the abnormal is to the normal condition of the one species, nothing more than what the normal condition of one species is to the normal condition of another; hence, I say that it is the same law which produces, in the one case, the normal and abnormal castes of form in the one spe- cies, and the normal castes of form in diverse species. If one human skeleton differs from another, as to the number of sternal ribs and of asternal ribs, and that in one we find the cervical ribs, in another the lumbar ribs, and in all some number of ribs or other, what is this variety, and whence has it occurred, but by the operation of that same law of metamorphosis which fashions the skeletal axis of a baboon of one number of ribs, that of a horse of another number, that of a sloth of another number, that of a cetacean of ano- ther number, that of a bird of another number, that of a reptile of another number, that of a fish of another number ? Is it not this same law which has fashioned all individual species of mammals of variable numbers of ribs ? all individual species of birds of variable numbers of ribs ? all individual species of reptiles of SKELETON. C.53 variable numbers of ribs ? all individual spe- cies of fishes of variable numbers of ribs also ? Is not numerical difference, as to costal, as to vertebral, and as to sternal elements, infinite ? Where, then, shall we find a resting place in this ever moving creativeness of the variety ? There is no resting place for the understand- ing, except in the idea of the skeletal arche- tj'pal uniformity, and there is no other mode whereby to mount to the recognition of this archetype, but by summing together all pro- portional variety, and constructing plus uni- formity from out of it. The number of osseous thoracic sternal pieces varies even in the same species ; it varies still more in the different species of a class, and general comparison carried through the four classes will prove incontestihly, that the region which is ventral, or minus the osseous ribs and sternum, in one animal (the human), is furnished with the ribs and sternum in another animal (the saurian), and hence becomes thoracic for this latter animal. In the mammal venter, the costo-sternal osseous pieces do not exist, but in the saurian venter they do. In the snme way will general com- parison prove that the region which is cervical, or minus the r'bs and sternum, in one animal, is furnished with the ribs and sternum in ano- ther animal, and hence becomes thoracic for this latter animal. In the mammal cervix, the costo-sternal osseous pieces do not exist as such, but in the ophidian and the fish they do ; for what else is the fish's hyoid apparatus but a series of ribs joining a sternal series ? Now, the true interpretation of the indivi- dual skeletal fabric is only to be had in the abstract or compound idea which springs from general comparison. The abstract or archetypal skeleton is the exponent of the special or individual skeletal fabric. The former is plus quantity, the latter is a special creation degraded from such a plus. The thoracic sternal series of the human skeleton commences, as bone, at the junction of the first pair of thoracic ribs, and continues as bone as far as the j miction of the seventh pair of ribs ; after this latter point the human sternum degenerates into cartilaginous or primordial tissue of the second stage of ossific process, and from thence it is continued over the ventral region in fibrous or primordial tishue of the first stage of ossification, and as such is united to the pubic symphysis, thus relating this point to the thoracic sternum, and also the pubic and ischiadic bones to the thoracic ribs, with which they are identical, no doubt. Those fibrous bands, named " lineae transversae" of the human venter, must be taken as sketches drawn in primordial sub- stance by the hand of nature, indicative of the ribs which are wanting at this region of series. Those ribs are proper to the lumbar vertebrae. The litiea alba is a sternal trace of archetypal osseous quantity, and is proper to the ribs which are now wanting at the mammal venter. The saurian venter, furnished as it is with both sternum and ribs, and lumbar vertebrae, must therefore be regarded as a nearer ap- proach to archetypal or thoracic uniformity than the mammal venter. In the former, the ventral region is embraced with an osseous costo-vertebral sternal apparatus, like the thorax. In the latter, the ventral rej^ion pre- sents this apparatus degenerated into pri- mordial or fibrous bands. The original of the mammal venter is thoracic, and, as such, I affirm that this original, although now only in idea, stands before the mental vision in as vivid a character as if its actual presence pre- sented to the corporal vision. That which is wanting at the venter of the manunal is equal to that which is persistent at the venter of the saurian ; and thus, in idea, 1 draw the sternal and costal osseous series over the ven- tral region of the mammal body. In every skeletal fabric where a venter is formed with- out the sternum and the ribs, nature may be said to have subtracted these for fitness and functional ease. The law of species requires that the costo- sternal series should not persist in the ventral and cervical regions of all animals, the reasons for which are obvious. It is by this law of special or proportional variety, which creates the cervix and the venter as fitting hiatuses in series, that the law of archetypal uniformity becomes eternally interrupted. The law of species is acting in constant nisus opposed to the law of plus quantitative uniformity. Both laws are eternal, and their eternal acts yield forms as they are. viz. a tinity in variety ; that is to say, a whole quantity undergoing a me- tamorphosis of parts. It is this metamor- phosis or subtraction of parts |)roper to the whole archetypal quantity, which furnishes all the endless sum of variet}'. The " xyphoid " cartilage and the *' manu- brium sterni " are the opposite extremities of sternal series in the mammal skeleton. At these extremities there is manifested, as it were, a constant tension or endeavour to extend the sternal line over the neck and abdomen. In the manunal body and others, this tendency to extend is held in constant subjection ; but occasionally we find that this nisus of the creative force advances a step, and marks its progress by the development of " episternal ossicles " at one end of the ster- nal line, and by additional nuclei of osseous substance at the other end. The character of either extremity of the sternal series is un- finished ; and even amongst the individuals of the several species of mammalia and birds, it cannot be said to be fixed. Sternal creation, and the law of its infinite variety as to length, can only be fiilly ascertained by extending the observation through general comparison. In general comparison, we readily discern the ability of creative i'orce exercising itself by the simple addition and subtraction of certain known elemental parts. By the addition of parts, nature mounts to archetypal uniformity ; by the subtraction of parts she degrades to variety. Every variety is but a subinultiple of archetypal uniformity. When I limit my observation to the indi- vidual mammal skeletal form, I find the 654 SKELETON. An archetypal /skeletal axis, constructed of the Piscean cervix, the Mammalian thorax, and the Reptilian venter and caudex. Showing the original serial continuity of the ribs and eternal median line. osseous sternal median line produced for the most part of set dimensions ; but when I extend my comparison through all individuals of that class, I find the sternum to be created of variable length, and constituted of variable numbers of elemental pieces. When, further, I carry my observations through all indi- viduals of the four classes, fishes, reptiles, birds, and mammals, I find that the osseous sternal median line has no limit short of the space which the maxillae mark before, and the pubic arches behind. Hence it is tiiat I call every sternal apparatus, which happens to be created of lesser dimensions than this space, as a specialty cut from the transcendent line of sternal median uniformity, such as J?g.480. represents, with the piscean neck ab, the mammal thorax c d, and the reptilian venter and loins e f. Isow, the hyoid appa- ratus (a,b,c,d) occurs at the median hue of the cervix (ab, ^^g. 480) ^^here we know costal quantity to be subtracted. The costo-sternal apparatus (a,b,c,d) happens at the median line of the thorax (c d), where we still view costal quantity persisting. Let these two facts be submitted to the focal light of com- parison, and I doubt not but that reason must draw the conclusion, that as the ventral sternum {k fc) relates the pubic symphysis (c* d) to the thoracic sternum (/, i), so does the hyoid sternum as a cervical ster- num (g, h) relate the maxillary symphi sis to the thoracic sternum {i, i). Hyoid ap- paratus is, therefore, but a name by which we designate the degree of metamorphosis to which the original costo-sternal series of a cervix has been subjected. It is this meta- morphosis which has rendered the costo- sternal quantities, proper to the cervical ver- tebrae, into the vocal organs of one class of animals, into the laryngeal organs of all ani- mals, and into the branchial organs of the fish (a b), in which latter class the character of the original costo-sternal apparatus is least modified ; for evidently the hyoid or branchial apparatus (a, b, c, d) of the fish (a b) is consti- tuted like the thoracic apparatus (a, b, c, d) of other animals (c d), of a series of ribs joining a sternal median line. The greater the degree of metamorphosis which the archetype has undergone, the greater is the obscurity of that structural analogy existing between organs of the same order in two or more animals. But though we are accustomed to limit the name sternum as applicable alone to the osseous part of the conuiion and general median line of the manmialian animal, and though we do not usually recognise as a sternum in this class that region of the median line which presents in cartilaginous structure, as, for ex- ample, at the neck and venter, still I maintain that, so long as it is acknowledged that com- parison is the only instrument by which we can ever hope to ascertain the law of form- ation in the creation of special differences, we must interpret the linea alba as being the continuation of the sternal line in the mammal abdomen, and the cricoid, the thyroid, and SKELETON. 655 hyoid forms, whether these be cartilaginous or osseous, as being the continuation of the sternal median line in the mammal neck. The history of the ossific process teaches us that every part of the skeleton which presents now in osseous structure, has passed through the prior stages of cartilage and of fibrous or cellular primordium. The general median line in front of the mammal form presents, in regional divisions, the one differ- enced from the other only in respect to these three stages of the ossific process. The thoracic sternal median division presents in the tertiary or osseous stage. The cervical sternal median division of this same line pre- sents in cartilaginous or secondary stage. The ventral sternal median division of this same continuous fine presents in the fibrous or primary stage. But whether the several divisions of this one sternal median line be, in the mammal body, of fibrous, or cartilaginous, or osseous tissue, it must still be regarded as the same unbroken sternal series from maxilla to pubis. The only difference which marks one class or species of skeletal form as dis- tinct from another throughout the animal kingdom, is simply the same as that which marks one region of the sternal line in one form diverse, or special, to another region of the same line in the same form. What the ventral or the cervical sternal median fine is to the thoracic of the same animal, namely phasially different ; just so is the ventral and the cervical median line of the several classes and species of animals diverse to the thoracic of all animals by a simple arrest of develop- ment in one or other of the three phases of the ossific process. The venter of a mammal is intersected with fibrous traces of the ster- num and ribs. This sternum and these ribs are of osseous growth in the saurian venter {k, k, Jig. 480.). The cervix of a mammal is intersected with the cartilaginous and osseous traces of original sternum and ribs, and these traces of the sternum and ribs are now called hyoid apparatus. The homologue of this hyoid apparatus, which is fashioned by the metamorphosis of sternum and ribs, is pre- sented in the osseous fish (g,Jig. 480.) as a sternum and ribs, to which we give the name hyoid apparatus. When I compare the foregoing anatomical facts together, I conclude that the abstract or archetypal skeletal fabric (Jig. 480.) to which comparison gives creation in my mind, is a form whose median sternal line is continuous from maxilla to pubis, from g to /, and in this archetype the ribs {a b) are holding continu- ous series. The vertebrae (a b, c d, e f) hold serial order in the same archetype also. The ribs succeed the hyoid apparatus, the pubic and ischiatic bones (c*c*) succeed the ribs, and the chevron bones (/j*Z>*) succeed the pubic bones. This serial order demon- strates the homological cast of all these parts, and therefore 1 have numbered them alike. When these serial parts are taken in connec- tion with the vertebrae behind, they constitute the archetypal series of whole quantities. Prop. XXXVIII. Evoy fossil skeletal species of extinct animals, as well as every recent existing species of skeleton, are forms created of the archetypal skeleton. — While we under- stand clearly, that it is the graduated meta- morphosis of certain parts from one or many of the serial sterno-costo vertebral archetypes which yields all spinal axes, variable as to the numerical lengths of a cervical, or a lumbar, a sacral or a caudal region, and while we know, even to a demonstration, that the tho- racic region results simply by the persistence of some of those archetypes, then we can readily understand that the persistence of idl the archetypal quantities would leave the form devoid of any such regional spinal variety as a neck, a loins or a caudex. And when I add to this remark this other, namely, that all the archetypes undergoing cervical metamorphosis would render all the spinal length in cervical character, or, if undergoing lumber metamor- phosis, would strike the whole spinal length in lumbar character, or if submitted to sacral or caudal metamorphosis would leave the whole spinal length of sacral or caudal stamp, then 1 see no reason why anatouiical science should marvel at the length of a plesiosaure neck as an extraordinary fact " dugout of the bowels of the harmless earth," however bizarre a creation this skeletal form may seem to the wonder-working geological speculator. Forms, as they are at present existing, and congeneric, seem to me to manifest, under contrast, no less a cause for wonder while I view them comparatively, than these same existing species of form can give rise to when I regard them comparatively with those of the lost or extinct species of a foregone time. But I believe that the only hope which science can ever entertain of solving the problem of formation in the past, must depend upon the demonstration of the process of the creative force, which rules formation in the present And when we shall have clearly demonstrated the creative law which at present strikes out the form of an ostrich in presence of the form of a whale, then we will cease to regard with doubtful interrogative the form of the Plesiosaure laid side by side with the Ichtliyo- saure, or any other figure the vestige of fore- gone creation. When science shall arm herself cap-a-pie with the knowledge of a law, then will she be enabled to contemj)late the past, the present, and the future, holding her statuesque gravity still unmoved, how- ever or by whatever show of seeming bizarre facts short-sighted ignorance may strive to startle her. Upon the proof of the truth of the reading here advanced, viz. that the cervical the lum- bar, sacral, and caudal spinal regions consist of spinal segments metamorphosed or de- graded from such archetypal segments as we find standing for the thoracic spinal region of all skeletons, depends the full and just inter- pretation of all varieties of spinal axes of animals, whether now existing or now extinct. Prop. XXXIX. The crania-facial appara- tus consists, like the thoranc apparatus, of 656 SKELETON. variable proportionals of the sterno-costo-verte- bral quantities. — The connection which exists between the cranial and the facial structures is quite as intimate as the connection which exists between dorsal vertebrae and thoracic ribs. In nature, we never find the cranial structures happening independent of the facial apparatus ; but we invariably witness the pre- sence of both, whenever the presence of one is manifested, just as is the case with dorsal vertebrae and the costal apparatus; and there- fore it is that when I shall presently draw comparison between cephaHc and thoracic regions of the spinal serial axis, I shall regard the one as a cranio-facial series of osseous quantities, homologous to the other as a costo-vertebral series. Before I {)roceed to compare the cranio- facial apparatus with the thoracic costo-verte- bral apparatus, let me here distinctly state one or two positions, which I shall not engage to define, simply because it would be impos- sible to prove that certain conditions were manifested, which are in fact and nature not manifest. Firstly, 1 do not mean to shew that an equality or quantitative uniformity characterises the cephalic and the thoracic regions of the one spinal series ; nor, secondli/, that all species of cephalic apparatus of the four classes are constituted of absolutely equal quantitative structure*, any more than thoracic apparatus are themselves ; nor, thirdly, that the number of cranio-facial seg- ments and the number of costo-vei tebral seg- ments correspond in the same spinal axis ; nor, fourthly, that the number of cranio-facial segments correspond in the cephalic apparatus of all animals of the four classes, any more than the thoracic apparatus of the same ani- mals correspond as to the number of spinal costo-vertebral segments. The so-called "Vertebral theory " appears to me to have jjlayed lightly with the serious patience of anatomical science, and to have brought itself into discredit, not because it has proved no one truth in generalisation at all, but because it has striven, while standing upon equivocal and un[)roven grounds, to de- monstrate that which had existence no where save in the imagination. An ill-defineJ sha- dowy resemblance was first seen to have ex- istence between cranial and spinal vertebral forms, and in puistiance of this idea has arisen all that vagrant and bizai're imagery * Ahnost all the anatomists of the French and German schools differ in opinion as to the number of modilied vertebrae which compose the head, for while some of them limit the number to three, viz. those which enclose the encephalon, others count as many as seven ; and these latter have increased the num- ber by absurdly likening the focial structures to the vertebral forms also. Goethe counts six, three of which comprise the cranium, the other three the face. Oken enumerates four ; Spix, three ; Cuvier, three ; Geoffroy, seven ; Cams, tliree (Lehrbuch der Zootomie) ; Meckel, three (Beitriig-e zur vcrglei- chenden Anatomic, Band II. S. 74.) ; Bojanus ad- mits four, and Burdach only three. Professor Owen enumerates four in the hsh, the reptile, the bird, and the mammal. See " Homologies," &c. which has enveloped the first dawn of a great truth in the smoke and mist of that sacrifice and homage which it was thought was due to the inspired genius of him* who first promul- gated it. I shall not here trouble either the reader or myself with a barren discussion about the merits or demerits of the views of those authors who sought to expand this ver- tebral theory beyond its natural limits, or of those who strove to discountenance the theory altogether, rather than to pursue it to the verge of sheer nonsense, ^ly present limits confine me to the observation of nature, and will not suffer me to canvass written opinion concerning her to any greater extent than such opinion shall be confirmed as cor- responding witn natural truth. Out of all that loose and flighty imagery which anato- mists of the transcendental school have in- dulged in, I select the first and only truth which has ever been fairly established, viz. that one respecting the homology between cranial and vertebral structures. That this homology exists between the osseous enve- lo|)e of the cerebral mass and the osseous coverings of the spinal chord, is now a fixed and immoveable fact in anatomical science. But though the existence of this honiolojry is now undeniable, still I may remark that every observation which serves to prove something further in respect to spinal verte- brcE, which had not been known previously to the recognition of this cranio-spinal resem- blance, must also prove that the same thing was unknown respecting cranial vertebrae. Every new fact, established upon the com- parison of spinal vertebrae, must be new also in regard to cranial vertebrae ; and this is the * Oken is generally acknowledged' as the signal discoverer of the homology between cranial and spinal segments. He believed that the cranial struc- tures were repetitions of the osseous quantities pro- per to the cervical vertebrne. It is said by some anatomists with Meckel, that Frank first recognised this analogy- between the skull and the vertebne (Sammlimg Auserlesener Abhandlungen, Band XV. S. 267.). Burdin supposed the head to be a com- plicated A'ertebra (Cours d'Etudes Me'dicales, Paris, 1803, vol. i. p. 16. \ Keilmeyer believed the same. Xext Geoffroy St. Hilaire, Dumeril, and Goethe ex- tended the theory, making such observations as are at present considered to be purely hypothetical, and little better than tanciful vagaries which ahnost overshadow the tirst truth. The similitude drawn by Goethe between the fiicial bones and the ver- tebrte, is scarcely less absurd than the likeness Avhich Oken and Spix are supposed to have seen between the temporal styloid process and the sacrum, or between the hvoid apparatus and the pelvis. Hence, it is not to be Avondered at why Cuvier mocked the cranial vertebral theory, when we tind Spix seeking for a repetition of the regions of the trunk of the body in the head ; and, because he would bend na- ture to his wild unstable fancy, whether she were willing or otherwise, so Ave have him representing the pelvis in the temporal bone ; and likening the hind limbs to the lower maxilla ; the auditory ossi- cles to the pubis ; the maxillary condyle to the femur ; the coronoid process to the tibia, &c. &c. See Cephalogenesis, seu Capitis ossei Structura. For Oken's A-iews of this subject, see Isis, 1S20, Xo. 6. p. 55'2. ; Esquisse d'un Systeme d'Anatomie de Physiol. Sec. Paris, 1821, p. 41.; also Ueber die Bedeutung der Schadelknochen, Jena, 1817. SKELETON. 657 point to which I direct the reader's attention, for it is upon this assertion that I found the present reading. If, for example, from fore- going remarks I have proved that the spinal vertebra is not a whole quantity, as it exists either in the cervical lumbar sacral or caudal regions, but that it is in reality a proportional metamorphosed from the sterno-costo-verte- bral archetype, then it must follow that the figure which has been named cranial vertebra is also a proportional metamorphosed from the like archetype; for that which is true of the form we name spinal vertebra, must un- questionably be true of the cranial form, which we liken to a vertebra. Now, in each of those spinal forms which hold serial order from cranium to the other extreme, there exists, as I have already shown, some proportional of the rib. In the thoracic spinal segment, the rib is plus, and meets its fellow of the opposite side at the sternal piece. This thoracic costo-vertebral form I have named archetype, and com|)ared with it I have shown that all other spinal vertebras vary from it, not because of the introduction of any new elemental part found in any of them, and not found in the archetype, but simply because they are, compared with this archetypal or plus quantity, the minus propor- tionals of such plus archetypes. However, it is still most true that the quantity which we recognise as the cervical lumbar or sacral vertebra, does contain within itself the rudi- ment of the rib, and therefore I repeat that t.'iis rib makes an integral part of all vertebrae -*-of all those, at least, which possess a certain quantitative character. It must have already appeared evident to the reader that it was premature to have sought to establish an identity between cranial and spinal segments, without having first ascertained the quantitative nature of the thing which was named vertebra. For as it was evident that something was yet to be proved by the comparison of spinal vertebrae, so therefore it was not possible to prove all that might be known of cranial vertebrae, while prematurely referring one unknown quantity to another equally unknown — I mean the spinal vertebra to the cranial verte- bra. Since it was by no means as yet demon- strated that the form which anatomists recog- nised as the spinal vertebra was a quantity of fixed and invariable character, how then could it be proved that the form to which it was likened in the cranium was of fixed and un- varying dimensions ? When anatomical science, lighted by the torch of Oken's genius, first pierced the mist and obscuring cloud of nomenclature, which described the cranial structures as distinct from the spinal forms, and when it expounded the facts and doctrine of that radical homo- logy of caste which related both classes of structure together under the conmion name vertebrae, it did not in truth progress nuich nearer to the explanation of the law of form than when it first explained, despite of no- menclature, the analogy which existed between VOL. IV. sacral bones and lumbar vertebrae. In the one case it only related hitherto unknown forms to vertebrae, without knowing the tvpi- ral form of vertebrce themselves ; in the other case it related the sacrum (sacer) to the lum- bar vertebrae, and called both vertebrae, with- out having any idea of the vertebral archetype or whole quantity. The facial apparatus is to the cranial forms just what the thoracic costae are to the dorsal vertebrae, namely, the integral parts of whole sacral quantities.* As in thoracic series, it is required that we should take the dorsal ver- tebra, holding its natural connection with the thoracic rib, and describe both as the parts of whole thoracic quantities; so in cephalic series, we are reminded, from the natural connection which facial structures hold with cranial forms, to describe both orders of parts as constituting the whole cephalic quantities. It is upon this connection apparent between facial and cranial structures at one region of series, and between vertebral and costal struc- tures at another region of the same serial order, that I am induced to draw a likeness or resL'mblance, as well between costal forms and maxillary forms, as other anatomists have recognised between cranial foriiis and spinal vertebrae. The identity which is already j)roved to exist between the latter n)ust prove the identity of the former likewise. The homology of caste which d priori reasoning establishes between cranial and spinal forms, wiil lead us to interpret by a posteriori reason- ing that an homology of caste must charac- terise the costal and the maxillary forms ; for if we are already forced to acknowledge iden- tity between cranial and spinal vertebrae, so must we, I contend, be induced to name the maxillae of cranial vertebrae to be the homo- logues of the costae of spinal vertebrae (even it special modification had rendered homology still more obscure than it is at present), and for this reason, viz. that costae are the natural attendants upon vertebrae, wherever we find vertebrae, whether in the head or in the spinal serial axis. As all spinal segments whatever contain some proportional of a rib, it must follow that the rib is to indicate the presence of the ver- tebral piece as nuich as the vertebral piece implies the presence of the rib ; and if the cranial forms are proved to manifest a struc- tural identity with spinal vertebrae, w hile we see that the latter are always attended with * If the facial be to the cranial structures just what the thoracic costje are to the dorsal vertebra;, then it will appear evident to the reader that, when Oken, or Spix, or Goethe, or Geoffiw likened the facial structures to vertebra?, they committed an error as evident as if they saw an analogy of form between the thoracic ribs and the verteljral pieces. Schultz (De Priniordiis Systeniatis Ossium et de Evolutione Spina? Dorsi in Animalibus) was the first to pronounce the gross error into which the trans- cendental anatomists had fallen in respect to liken- ing the facial apparatus to the vertebral piece3. Bojanus, in like manner, prudently freed himself from this error. Professor Owen considers the facial apparatus to consist of the " inverted arches" of the cranial vertebrre. u u 658 SKELETON. the ribs, then the cranial vertebrae, as verte- of cranial vertebras, if these ribs be not tlie brjE, must have the ribs also. What other maxillary arches ? * cephalic structures, therefore, are there in the Now there happens mjig. 481., between the head which may be said to stand as the ribs costiform maxilla {dd*) and thoracic ribs rig. 481. The human cranio-facial and ceTvico-hyoid apparatus. Shelving tliat the liyoid apparatus relates to the cervical vertebrae, aud the facial apparatus to the cranial vertebra;, just as the thoracic or costo-stemal apparatus relates to the dorsal vertebra;. (f P*)' that hiatus or gap in costal series which is called the cervix, and it is this hiatus * In the " Homologies," the author names the maxillae the "inverted arches" of the cranial ver- tebrae. These inverted arches answer to the haema- pophyses of the author's ideal typical vertebra, and not to the pleurapophysial elements (the ribsj of that ideal foiiii. Now I confess, for my own part, that I do not see clearly why these maxillary arches are referred to the former rather than to the latter elements. There is e^^dently some mystery about this ideal typical vertebra tigured in the " Homo- logies," which I cannot penetrate, and for this reason, viz. that I find the author's " ideal tj-pical {q q q) which interrupts the idea of a con- tinuous serial costal order ; at the same time vertebra," while compared to the osseous segment taken from the bird's thorax, and which he terms the " natural typical vertebra," does not con-espond quantitatively. In this ideal form I tind the ribs (pleurapophyses) but as niere rudiments, whilst in the natural form I see that these ribs emljrace tho- racic space from the spine nearly to the sternum. Again, in the ideal form the hasmapophyses hang appended to the vertebral centrimi ; Avhereas in the natural tji^ical form they articulate %vith the distal ends of the thoracic ribs. SKELETON. G59 that vertebral series (g, h, i, k, l, m, n) is still uninterrupted as it passes from dorsal ver- tebrae (p), through cervical vertebrje, to cra- nial vertebrse (f, e, d, c, b, a). Thus we find that vertebral series persists continuously, while costal series is interrupted by the cer- vical hiatus happening between the maxilla above and the thoracic costae below. This hiatus is caused by the degradation of costal quantity simply, for we still see that rudi- mentary ribs (g, h, i, k, I, m, n) are developed upon each of the cervical vertebrse. If the original plus ribs of the cervical vertebrae still persisted at the lines qqq, for them as the plus ribs (pp*) do for the dorsal ver- tebrae, then we should have the maxilla hold- ing serial continuous order with the thoracic ribs, in which case it could scarcely be doubted that the maxillae were structural homologues of the costae elsewhere. But in this occur- rence of cervical hiatus, which results by the metamorphosis of that plus costal quantity which I consider to be originally proper to the cervical vertebrae, we have the facial ap- paratus now disconnected from the thoracic apparatus ; and the only structural entity which at present relates the maxilla above to the costae below is the hyoid apparatus (f*,g*, h*, I*, k*). Hence this latter structure can come of no other source than cervical original costal quantity under metamorphosis. The idea of the plus costal quantity, which we now know to be lost at the cervix, is equal to the idea of the same quantity pre- sent ; and hence, when I say that they are the plus ribs which are lost to cervical vertebrae, it is as strong an idea as if I still viewed them persisting at the lines qq q. If these cervical plus ribs still persisted, they would leave no doubt that the maxillae are of costal origin. Indeed the maxillae, as they at present stand, prove a much stronger resemblance to ribs than cranial vertebrae do to spinal vertebrae ; and if we see little reason to doubt the iden- tity between the latter structures, there is, as it seems to me, even still less reason to doubt the homology or correspondence between the two former. In ^g. 481. I have indicated the number of those vertebral forms which constitute the human cranium, taking as my guide the in- variable attendance of the costal structure upon the vertebral structure, as well in the head as in all other regions of the spinal axis. The first dorsal vertebra (p) is attended by the plus ribs stretching over tho- racic space from the back to the sternum. All the cervical vertebrae (n, m, l, k, i, h, g) are likewise attended by the minus costae (}i,77i,l,/c,i, h,g). From these severally I have produced lines to the hyoid apparatus, and these lines, together with the hyoid pieces, indicate thoracic costo-sternal quan- tity, which metamorphosis has degraded down to the quantities at present forming the cervi- cal region. The intervals between the cervi- cal lines of the original costae are marked (79) as corresponding wiih the intercostal spaces. The atlas (g) supports the occipital or first (reckoning from below) cranial vertebra. In the atlas vertebra* may be recognised (g) the vertebral end of its rib, which when pro- duced through the line q joins g, the greater cornu of the hyoid bone, to which latter the body g* is attached ; this group of elementary parts represents the debris of the archetypal sterno-costo-vertebral quantity ; the atlas stands in series with the other vertebrae, while the inferior half of the hyoid bone holds series with the sternum. The axis vertebra (h), in the same way, corresponds to the (/«*) thyroid cartilage. The third cervical vertebra (i) corresponds to the cricoid carti- lage (/*). The fourth vertebra (k), the fifth (l), the sixth (m), point to the rings of the trachea. The seventh vertebra (x) stands opposite to the clavicle (72), which I regard as the costa of that vertebra. The ^rsl or occipital costo-vertebral quan- tity of the head consists of (f) the centrum and the pieces V'^''\ 2, 3, which form the neural arch and spine. The rib and sternum or costo-sternal quantity of this vertebra is re- presented by the styloid process (/), which, when produced in a Ime to (/*) the upper half of the hyoid body with its lesser cornu, completes this group of elemental parts.-|- The second or j)etrosal costo-vertebral quan- tity of the head consists of (e) the centrum and the parts V"'\ 2, answering to the neural arch and spine ; the costo-sternal quantity of this vertebra is represented by the tympanic bone {e) coiled upon itself, and enclosing within its circle the auditory ossicles. The tympanic bone, together with the auditory ossicles, may be regarded as costo-sternal quantity, specially modified in subservience to the special sense of hearing.| The third or temporal costo-vertebral quan- tity of the head has no part corresponding to the body at d ; but the neural arch and bicleft spine of this segment of the skull are repre- sented by the parts V"\ 2. The costo-sternal quantity of this vertebra is represented by the lower maxilla (d) articulating like a rib with the glenoid cavity (r/). ^ The fourth or post sphenoid-costo-vertebral quantity consists of (c) the centrum and the parts 2, answering to the neural arch and spine. The costo-sternal quantity of this vertebra is represented by the zygoma (c, c) and upper maxilla (c*). * Professor Owen refers the clavicles to the atlas vertebra, and considers them as forming the hsemal inverted arch of this vertebra. See " Homolo- gies," &c. t The scapixlary limbs are referred bv Professor Owen to his occipital vertebra, of which he consi- ders the scapulae to be the ribs, and the rest of these members to represent Avhat he terms the " diverging appendages." X Professor Owen does not regard the petrous bone as a part of a cranial vertebra, but he calls it a " sense capsule," and refers it to the splanchno skeleton. § The styloid process is regarded bv Professor Owen as the rib of his parietarvertebra.' u u 2 660 SKELETON. The Jifth or anterior sphenoid costo-verte- bral quantity consists of (b) the centrum and the part V\ as the neural spine. The costo- sternal quantity of this vertebra is represented by {h) the palate bone. The sixth or ethmoidal costo-vertebral quantity of the head consists of (a) the cen- trum, with the part 1' as the neural arch. The costo-sternal quantity is represented by the nasal bones (o). Now, consitlering^o-. 481. as a Avhole, I find it to be characterised in certain ways, which still further prove the nature of the fact, that the human head consists of six* costo- vertebral archetypes, as numbered above ; and though I by no means would have it under- stood that I consider each of those cranial archetypes to be equal in quantity either to one another or to the first sterno-costo-ver- tebral quantity of the thorax, still I find that there are certain sutural marks in the human head and facial apparatus, which seem to define, with sufficient clearness, those natural groups of bones which form the archetypal quantities. The spaces called intervertebral, amongst the spinal vertebrse, viz. those spaces w hich occur between the neural arches of two adjacent vertebrae, such as g and H,are repre- sented by all the transverse sutures of the cranium. Those sutural intervertebral inter- vals I have marked thus : Between the axis h and the atlas g, the intervertebral space is ^/////// . between the atlas g and the occipital form, the sj)ace is o''"" ; between the latter and petrous form is the lambdoidal suture o''^'\ and so on. The intercostal spaces are marked ^, q. Sec. When we seek to determine the nature of the sutures of the cranial structures by com- parison with the serial vertebrae of spinal order, we should bear in mind the fact that one order of the cranial sutures mu-t cor- respond to the intervertebral spaces of spinal vertebrae, while another order of cranial sutures must answer to those points where the elements constituting each vertebra join. Thus, whilst such sutures as the coronal (/ig. 481. o\) and lambdoidal answer to the intervertebral spaces (o'""''), the sutural temporo-parietal point of union between T"' and 2 answers to the point of junction be- tween the elements 1, 2 of the atlas vertebra G, or of the axis h. The frontal suture is that line of union which the symmetrical laminae of one vertebra ot the spine would, when meeting each other at the median line of neural space, represent. The sagittal suture is a biclevage of the spinous process (viz. the symmetrical parietal bones) of that vertebra of the head to which they belong. As the nerves passing from the spinal cord bear a somewhat fixed relation to spinal ver- * Professor Owen eniuiierates four cranial verte- brae, viz. tlie occipital, parietal, frontal, and nasal, lie regards the ethmoid to be a sense capsule, like the petrosal bone, neither of which he considers to be parts of vertebras. Oken held the same opinion. Spix, Bojanus, and Geoffroy left these bones unde- termined as to their homological signification. tebrae, so might we expect that the nerves of the encephalon should bear the like relation- ship to the cranial vertebral quantities. A spinal nerve passes between two adjacent ver- tebrae, and thus to six spinal vertebrae there correspond five nerves. I have enumerated six cranial vertebrae, each one with the costal quantity, and hence the nerves passing between these six should number five, like those of the spine. These cranial nerves I consider to form five natural groups, as follow : — The first or olfactory nerve, being one of special sense, is distributed upon the ethmoid vertebra (Jig. 481. a). The second is a group of motor and sensory branches, consisting of the optic, the third, and the fourth nerves, which pass through the optic and lacerate foramina or cleft, which occurs between the ethmoid and anterior sphenoid vertebrae. The t/tird group of nerves is motor and sen- sory, consisting of branches of the fifth, which pass through the foramen ovale (fg.A'S2. e). The fourth group of nerves is motor and sen- sory, consisting of the portio mollis and portio dura ; one of these nerves is distributed to the organ of hearing, and the other makes exit at the stylo-mastoid foramen (^/ig. 482. r i'), being destined for the side of the face. The Jifth group is also motor and sensory, and consists of the eighth and ninth nerves pass- ing out through the foramina (/, t), viz. the anterior condyloid and foramen lacerum pos- terius. The groups of foramina, which I consider as answering to the intervertebral foramina of the spinal series, are indicated in Jig. 482., each group being surrounded by a dotted line, as at the point e, the place s, m, r, and the place /, /. The other two intervertebral foramina are not seen in this view of the cranial base. It is a singular fact that the external meatus occurs like a true intervertebral foramen between the petrosal and temporal vertebrae, w hich in the early foetal condition are naturally separated. When I view the serial order of the inter- vertebral foramina of the cervical spine, I find that the external meatus exacth coincides with the series. There are many facts of interest which re- cur to me regarding Jig. 4:82. as a form com- parable to vertebrae ; but since to record these in full would exceed the space allotted to this article, 1 must forego the task, and only remark in brief, that afl the other fora- mina of the cranial base give passage to arterial and venous vessels like the vertebral foramina (gg) of the atlas and {h k) of the axis. The cranial base (Jig. 482.) gives evidence of a certain fact of special modification of so large an interest, that I cannot but advert to it : the fact is this — the body of the axis (8, 8) passes through the body of the atlas (7, 7), and carries part of this latter (q, q) before it as its odontoid process. The body of the oc- cipital vertebra (6, 6), passing forward to the body of the post sphenoid vertebra (3, 3), sunders the body of* the petrosal vertebra (5, o), while the bcdy of the parietal vertebra SKELETON. C61 is altogether obliterated. By this circum- or post sphenoid vertebra, the cranial basis stance of the body of the sixth or occipital is contracted in its longitudinal axis, while cranial vertebra joining the body of the third the cranial vault {fig. 481.) fashioned of the expanded neural arches, affords ample space wherein to locate the crescent organ of the intellect. Prop. XL. The scapulari/ or fore-limbs of all the vertebrated animals are homologous to one another. The variety among these organs occurs by a metamorphosis or omission of ele- mentary quantity. — The right scapulary organ is perfectly identical with the left in the same animal body. Both the fore-limbs of the human body are identical ; those of other mam- mals are identical ; those of a bird are iden- tical ; those of a reptile are identical ; and those of a fish are also identical. Os- seous quantity is equal for both fore- limbs of the same animal. But the fore- limbs of all animals are not quantitatively equal, far from it. The fore-limbs of a mam- mal differ by quantity from the fore-limbs of a bird, those of a bird from those of a reptile, and those of a reptile from those of a fish. The mammal fore-limbs manifest a quantitative difference amongst all species of that class ; the avian fore-limbs the same ; the reptilian fore-limbs the same ; the piscean fore-limbs the same also. The ana- tomist who would undertake the task of re- cording the quantitative difference manifested amongst all the fore-limbs of the vertebrated classes, would require a chart as free as space and a leisure as unconfined as time. As quantitative difference is of such infinite ac- count, I shall not therefore record it by the numerical method ; but my task shall rather be to develop that idea in generalisation, which will interpret the infinity of variety as u u .3 660 SKELETON. being the product of a law of metamorphosis, exercising itself upon the whole quantity or unity. Comparison teaches me the fact that not only are the fore-limbs of the animal classes varied amongst themselves as to osseous quantity, but 1 find that even the individuals of any one species have not the fore-limbs developed of invariably fixed and equal quan- tity ; for there is no one species free from the possibility of that occurrence which we term "anomaly." The human hand is seen to develop (by no means unfrequently) a plus number of digital appendages. I have seen the hke anomalies upon the fore-hands of the Quadrumana. The Ruminantia now and then develop in the fore-foot solipedal character. The solipedes are known to pro- duce the fore-limbs in cloven stamp some- times. The individuals of every species, I doubt not, would, if we studied them with sufficient care and in large masses, prove themselves to be subject to the occurrence of a plus or minus quantitative variety to that character which is general or normal with them. It is because I find that these ano- malies to species are facts not more mar- vellous in themselves than are the facts which vary species to species, that I will here embrace them in the general interpretation of a plus unity undergoing metamorphosis for the creation of variety. The variety between species can be nothing more than the variety which the anomaly proves to the species of normal character. There is no member of the animal fabric which more interestingly illustrates the fact that nature adheres to a unity of type than does the osseous fore-limb. Whatever be the variety which fore-limbs manifest, when comparatively contemplated, still we find that the bond of unity embraces and girds within its circlet the whole subject of the variety. A proof of this fact may be seen Fh. 483. A, the fore limb of the lion ; b, that of the wild boar ; c, that of the rhinoceros ; D, that of the bull ; E, that of the horse ; showing a serial degradation from plus to minus quantity. even in the use of that nomenclature, by tude the one to the other, we should not and which we designate all varieties of the sea- could not afford to generalise them under the pulary organ; for, were it not that all such common appellation ofscapulary organ, members proved a greater or lesser .simili- The fore- limbs of all osseous skeletal fabrics SKELETON. 063 483.) are alike as to those segments which constitute them one and all. Those segments are the scapula («, a), the humerus {b, b), the fore-arm bones (c, d), the carpal ossicles (e,/), and the metacarpo -phalangeal series (1, 2, 3, 4, 5). Every species of the fore member produces these segments in- variably ; I say invariably, for I am not now referring to their pathological state. When I compare all fore-limbs by the scapula (a) or proximal segment, I find that this bone is invariably present, though very much modified in several animals. As all scapulary organs of mammals, birds, reptiles (and I would add the osseous fishes, but for certain facts which require previous expla- nation,) produce the bone named scapula, they may be hence termed uniform as to this particular. The invariable occurrence of the humerus {b) renders them likewise uniform as to this segment. But though the fore-arm carpus and metacarpo-phalangeal segments are, as segraentSj invariably present likewise, still all fore-limbs are not equal or uniform as to the quantity contained in each of these segments. Considering the fore-limbs under general notice, I see that they are uniform by the proximal ends (a, b) of the organs, and variously by the distal or terminal appen- dages. But it is most true, nevertheless, that this variety is only quantitative, or simply a plus and minus variation, for a produces five digits, B four, c three, d two, and e only one. Of the two bones (c, d) constituting the fore-arm, that one which is most constantly developed in entire proportions is the ra- dius (c). The ulna {d) is very often reduced to almost unrecognisable dimensions {d of e) ; and that part of the ulna which is most gene- rally metamorphosed or annihilated is its distal or carpal extremity. The olecranon process and a part of the shaft of the ulna is always present. The carpal ossicles (e,f), which in all fore- limbs manifest a greater relationship to the radius (c) than to the ulna {d), are as constant as the radius itself. The n)etamorphosis of the ulna {d of e) does not appear to affect the carpal ossicles (