Digitized by the Internet Archive in 2015 https://archive.org/details/cyclopaediaofana4184todd THE CYCLOPAEDIA OF ANATOMY and PHYSIOLOGY. VOL. IV.— PAET I. PLE STA 1817-1849 THE CYCLOPAEDIA OF ANATOMY and PHYSIOLOGY. EDITED BY ROBERT B. TODD, M.D. F.R.S. FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS; PHYSICIAN TO KING’S COLLEGE HOSPITAL; AND FORMERLY PROFESSOR OF PHYSIOLOGY AND OF GENERAL AND MORBID ANATOMY IN KING’S COLLEGE, LONDON, ETC. ETC". YOL. IV.— PART I. PLE STA 1847-1849 15703 LONDON LONGMAN, BROWN, GREEN, LONGMANS, & ROBERTS. CONTENTS OF THE FOURTH VOLUME. Pleura S’. R. Pittard, Esq. Page 1 Polygastria Professor R. Jones 2 Polypifera Professor R. Jones 18 Popliteal Region ... TU. Trew, Esq. 60 Porifera Professor R. Jones 64 Products, Adventitious Dr. Walshe 71 Prostate J. Adams, Esq. ... 146 Protein Prof. J. E. Bowman 162 Pteropoda Professor R. Jones 170 Pulse Dr. Guy 181 Quadrumana Professor Vrolik . . . 194 Radial Artery Dr. Brinton 221 Radio-ulnar Articu- 1 lation J ► Dr. Brinton 228 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 JV. Ward, Esq. 422 Scapular Region Dr. M' Dowel 433 Scrotum Dr. Brinton 438 Secretion Dr. Carpenter 439 Semen r Drs. Wagner and ) L Leuckhardt J 472 Sensation Dr. Todd 508 Sensibility Dr. Todd 510 Serous and Synovial-] Membranes J | -Dr. Brinton 511 Sesamoid Bones S. R. Pittard, Esq. 541 Seventh Pair of Nerves Dr. Brinton 543 Shell Dr. Carpenter 556 Shoulder Joint (Nor- -] mal Anatomy) J j- Dr. Mr Dowel 571 Shoulder Joint (Ab- normal Conditions of) j- Robert Adams, Esq. 577 Sixth Pair of Nerves Dr. Brinton 621 Skeleton Joseph Maclise, Esq. 622 Sleep Dr. Carpenter 677 Smell Dr. Carpenter 697 Softening and Indu- ration J j- Dr. P. M. Duncan 703 Page Solipeds Professor B. Jones 713 Spmal Accessory, ) ^ Nerve J Spinal Nerves N. Ward, Esq 750 Spleen Professor Kulliker 771 Statistics, Medical ... Dr. Guy 801 Subclavian Arteries Dr. M' Dowel 814 Supra-renal Capsules Prof. Heinrich Frey 827 Sweat Dr. G. O. Pees ... 841 Symmetry S. P. 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 'i Articulations \ S. R. Pittard, Esq. 937 Teratology Professor Vrolik ... 942 Testicle T. B. Curling, Esq. 976 Thorax Dr. Hutchinson 1016 Thymus Gland Dr. Handfield Jones 1087 Thyroid Gland Dr. Handfield Jones\\0'2 Tibio-fibular Articu- o lations \Dr- M‘ Dowel 1118 Tongue Dr. Hyde Salter ...1120 Touch Dr. Carpenter 1163 Tunicata Professor R. Jones 1185 Urethra John Adams, Esq. 1244 Urine Dr. G. Owen Rees 1268 Varieties of Mankind Dr. Carpenter 1294 Vein S. Jas. A. Salter, Esq.\367 Venous System Dr. M 'Dowel 1403 Vesicula Prostatica... Professor Ltuckhardt 1415 Vesiculae Seminales S. R. Pittard, Esq. 1429 Vision { W- White Cooper, j 143g *- Esq. J Vital Statistics Dr. Guy 1459 Voice John Bishop, Esq. 1475 Wrist Joint (Normal 1 ,, Anatomy, \Dr' M‘Dowd 1505 Wrist Joint ( Abnor- ~| oral Conditions of) JR E*>- -'5M 15703 THE CYCLOPAEDIA OF ANATOMY AND PHYSIOLOGY. PLEURA is the 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 two 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 costs 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 pleura, 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- stinum 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-posterior 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 mediastmaare 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 contains the bifurcation of the trachea, the arch of the aorta, the pulmonary and other great vessels ; the posterior contains the aorta, (Esophagus, &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 pleurae 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 two pleurae come into adhesion with one ano- 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 pre vented 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 (ligarnentum 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 epiploic®. 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 pleura 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 pulmonalis , pleura costalis, and pleura diaphragmatica, are applied respectively to those parts of the pleura 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 in 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. 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 Anentera.-)- 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, * ttoXii;, many ; yaa-Thf, a stomach. t a, pris. ; IvTSpor, intestine. terminating by an anal orifice : these have been named from this circumstance Enterodela.s The Euterodelous 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. (CYCLOCCELA.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 Orthoccela.| 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 Campy loccela.§ 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. — MoNADrNiDaL (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, fig. 1.) Polytoma, (2, fig. 1.) Microglena, (3, Jig. 1.) Phacelomonas. Glenomorum. Doxococcus. Chilomonas. Bodo, (4, Jig- 1.) Family 2. — Cryptomonadi nidie. Poly- gastric animals, presenting all the characters of the Monadinids, 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 , Jig. 1.) Cryptoglena. Trachelomonas. Family 3. — Volvocinid,3E. Polygastric ani- mals, without intestinal canal, without external * EVTspoV) intestine; manifest. t xukXo$, a. circle ; xoTxoj, large intestine. } straight ; xoTxo;, intestine. § xa^uTruXo?, crooked ; xo7xo$, intestine . || 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 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 becomes 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, fig. 1.) Chlamidomonas. Spharrosira. Volvox, (fig. 3.) Family 4. — Vijbrjonid®. Animals either distinctly or most probably polygastric; fili- form ; without alimentary canal ; without shell or external appendages ; with the uniform body of Monads; associated in filiform chains in consequence of imperfect spontaneous (trans- verse ) division. Bacterium. Vibrio, (1, 2, 3, 4, 5, fig. 5.) Spirochaeta. Spirillum. Spirodiscus. Family 5. — Clostf.rinid*. Animals dis- tinctly or most probably polygastric, without alimentary canal, and without external appen- dages ; body uniform, resembling the Crypto- monadinidse in their envelope or shell, and dividing, together with their envelope, by spon- taneous, transverse fissure, into a baeilliform or fusiform polypary ; provided with moveable papillae situated in the aperture of the shell. Closterium, (6, 7, fig. 5.) Family 6. — Astasieadas. 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, (1, fig. 6.) Amblyophis, (2, fig. 6.) Euglena, (3, fig. 6.) Chlorogonium, (4 , fig. 6.) 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. — Amoebaeadaj ( 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- malcules). 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, (\,fig. 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. Pantotrichum. 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 distinct 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. Stenlor, (fig. 8.) Trichodina. Urocentrum. Vorticella, (fig. 9.) Carchesium. Bpistylis. Opercularia. Zoothamnium. Family 14. — Opiirydinidje (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. (= Vorticellina loricata.) Ophrydium, (fig. 10.) Tintinnus. Vaginicola, (9, fig. 11.) Cothurnia. Family 15. — Encheliad® (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, fig. 11.) Disoma, (6, 7, fig. 11.) Actinophrys. Trichodiscus. Podophrya. Trichoda. Lachrymaria, (8, fig. 11) Leucophrys, (1 , fig. 12.) Holophrya. Prorodon (2, fig. 12.) Family 16. • — ■ Colepinid® (Box Ani- malcules). Polygastric animalcules, having a distinct intestinal canal, the mouth and anus TOLYGASTRIA. 5 being situated at the opposite extremities of the body; loricated. = Encheliadae furnished with a shell. Coleps, (1, 2, fig. 13.) Family 17. — Trachelinid® ( Neck Animalcules ). Animals polygastric, furnished with a distinct intestinal canal, haring an oral and an anal opening, but of these the anal opening only is terminal ; without shell. Trachelius, (3, 4, 5, fig. 13.) Loxodes. Bursaria. Spirostoma. Phialina. Glaucoma. Chilodon. Nassula, (1, fig. 16.) Family 18. — OpHEYOCERCiNiDa: (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, fig. 16.) Family 19. — Aspidiscinid/e (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. — Colpodeadze ( Breast Ani- malcules). Animals polygastric ; without a shell ; intestinal canal distinct, with two open- ings, neither of which is terminal. Colpoda, (2, 3, fig. 18.) Paramecium, (1, 4 , fig- 18.) Amphileptus, (2, fig. 16.) Uroleptus. Ophryoglena. Family 21. — Oxytrichinid* (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. — Euplotidje. ( 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, (fig. 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 : — lsf 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. | Bacillaria. Second Division. — ENTERODELA. This division includes all animalcules having an internal digestive canal provided with a mouth and anal opening. 4 th Section. Anopisthia. Mouth and anus contiguous. Nuda. I Loricata. Vorticellina. | Ophridina. 5th Section. Enantiotreta. Mouth and anus terminal and opposite ; re- production by transverse division. Nuda. Enchelia. 6th Section. Loricata. Colepina. Allotreta. Mouth and anus terminal and opposite, as in the last section ; reproduction by longitudi- nal and transverse division. Nuda. Trachelina. 7th Section. ' Loricata. j Aspidiscina. Katotreta. Mouth and anus not terminal ; reproduction 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, fig. 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 Cryptomonadinid® 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 Vibrionid® 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 causeof 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 Arcellinid®. 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 Stylo- nychia mytilus, and the latter in Paramecium uurelia. In addition to the cilia some forms of ani- malcules ( Oxytriduna ) possess seta, which are likewise stiff moveable hairs, but which are without any power of vibration ; these organs are used in standing and climbing. Sometimes they are without any thickened basis, as in Actinophrys ; generally they are pointed, but occasionally have a knob at the end. A fourth set of locomotive organs are the styli. These are thick straight set®, which in some forms of animalcules are attached like the tail fea- thers of a bird to the hinder part of the body ot the animalcule : such styli do not vibrate like 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 ventral 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 MoNADi.NiDa: 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 Monas crepusculum, 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, gJojth of a line in diameter, their number will then amount, in a drop of water of the size of POLYGASTRIA. 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 ! 1 ! 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 glaucoma. 2. Polytoma uvella. 3. Mi- cruglena monadina. 4. Bodo socialis. 5. Lagenella euchlora. 6. The same crushed, showing its shell. 7. Gonium pectorale. 8. Gonium pectorale, breaking up into its component animalcules. 9. Eudcrrina. 10. One of the animalcules comprising Eudorina 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 JJvella, (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, Jig. 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, Jig. 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 intestines 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, Infusionsthierchen. they are bound together in bunches of very beautiful appearance, as represented in the figure. In the Cryptomonads, (5, Jig. 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 the component 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, which 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 ap- 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 Volvocinidse are the Vo/voces, from which 3 POLYGASTRIA. the 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 (jig. 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 ig-sSmSSSsia WMte&Mataat 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 gemmules 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 * Abhandlungen tier Koniglichen Academie der Wissenschaften zu Berlin, Jalir 1833, p. 328. 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 Monadinid®, and that the Volvox was entirely made up of an association of similar individuals (fig- 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. Fig. 4. POLYGASTRIA. 9 On closer inspection it is seen that all the Monads, 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 the 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, 1 3, fig. 1. In 11, fig. 1, is represented the simplest con- dition of a granular mass containing a clear central spot, which in the course of a few 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 VibrionidK, 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, Vibrio, the Fig. 5. 1, 2, 3. Vibrio subtil is. 4. Vibrio rugula. 5. Vibrio rugula more highly magnified. 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 Vibrionidas 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, fig- 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 (1, jig. 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, jig. 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 Sertularia. In the next family, Amoeba, locomotion is accomplished in a most extraordinary manner, these animals apparently possessing the power of making fooi-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 shooting 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, Vi, jig. 6.) 1 . Astasia Jiavicans. 2. Amblyophys viridis. 3. Euglena acus. 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 difjluens, exhibiting a few of its changes of form. The genera Difflugia, Arcella, and Cyphidium (1,2, 3, fig. 7) seem to be merely Amoebaa 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, Pantotrichum, and Clueto- monas, and their loricated representatives, CIue- tutypla, Chatoglena, Peridinium, and Gieno- dinium, forming the families Cyclididae and Peridinaeadae, we first find a new system of locomotive organs making their appearance in the shape of vibratde 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 animalcule 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. Difflugia oblong n. 2. A rcella dentata. 3. Cy- phidium aureolum . POLYGASTRIA. The genus Stentor (Jig. 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 Fig. 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 front near the mouth to a considerable distance towards the hinder part of the body, the outline of which lias an undulated appearance. The Trichodinte, 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, JJnio, &c.,) 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 Vorticella, (fig. 9,) the sight of which cannot fail to exact the untiring admiration of the microscopical Fig. 9. Stentor Roeselii, highly magnified, t, viscus supposed by Ehrenberg to be the testis. Vorticelln 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 highly 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 slightest 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 the 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 orifice, the situation of which is nearly the same as in Stentor, above described, and thus the little being is abun- dantly supplied with food. The true Vorti- cellaj, although generally found grouped toge- ther in elegant bunches; always have single undivided stems; but in the genus Carchesium, the animals of which are similarly organised, the pedicles sprout from one another so a§ to' have a branched or ramose appearance, while in the genus Epistylis, 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 ” ( Saulenglvckchen ). The family Ophrydinidte presents us again with very remarkable forms of Polygaslric 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 Ophrydium, (jelly-bell-animal- cules,) of which the Ophrydium versatile (fig. 10) is an example, was regarded by the older 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 Miiller, 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 3'5th of a line in thickness, and about the ^th 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 ( Alcyonida ) 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, fig. 11,) and Cothurnia, although living in gelatinous transparent sheaths, and resembling Vorticella; in their structure, are not associated in masses, but remain permanently detached and solitary. The family Encheliadse 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 : — Enchelis, (revolving animalcule,) has its body flask-shaped, (1, fig. 11,) without any cilia externally, but with a circlet around the mouth, which is suddenly truncated and desti- tute of any dental armature. Disoma, ( double-bodied animalcule,) crea- tures nearly resembling Enchelis in form and structure, but with a double body (6, 7, jig. 11). Actinophrys, (sun animalcule,) having the exterior of the body unprovided with loco- motive cilia, but stuck over with setaceous ten- tacula which radiate in all directions. Trichodiscus, ( radiated disc animalcule,) re- sembling Actinophrys, only the body is here Fig. ll. 1, 2, 3, 4, 5. Enchelis farcimen , swallowing food. 6,7. Disoma vacillans. 8. Lacliry maria proteus, 9. Vaginicola decumbens. POLYGASTRIA. 13 compressed, and only furnished with a single row of setaceous tentacula, situated around its margin. Podophyra, ( radiated foot animalcule,) is an Actinophrys 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. Lachrymaria, ( lachrymatory animalcule,) (8, jig. 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 and provided with a kind of lip, but without dental organs. (1, fig. 12.) Holophrya, ( woolly animalcule,) an En- clielis 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 patula. 2. Prorodon teres, o, 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 ) The family Colepinidae consists of but one genus, Coleps (1, 2, fig. 13), the animalcules belonging to which have all the characters of Enchelis, except that they are loricated. These animalcules are found among conferva, more especially in summer time. As long as they are swimming it is difficult to perceive the transparent case in which they are enclosed ; but if they 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 rings, be- tween which the cilia seem to be exserted ( testula 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, Trachelinidee, 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 Fig. 13. 1, 2, Coleps hirtus. 3, 4. Trachelius anas. 5. Tra- chelitis ovum. o, mouth; a, outlet of alimentary canal. will be able readily to recognise them by the following characters : — Trachelius (neck animalcules, 5, fig. 13). These may be readily known 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 known appellations. Attentive examination, however, shews that the mouth is situated at the bottom of this neck-like prolongation (3, 4, fig. 13), and not at its extremity, as was the case in 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 Trachelius 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, with 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. intestinalis, and B. cordiformis, live parasitically in the intes- tines of the frog, toad, and water-newt. The genera Spirostomum ( 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 line 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 muller, 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 oesophagus of a snake when it swallows a rabbit, and immediately collapses again, and becomes quite invisible when not actually i 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, Voriicella 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). Id 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 cvcullus (Synonyme, Kul- poda, Loxodes cucullus ), Nassula ornata, Nas- sula elegans, Nassula aurea, Prorodon niveus, Prorodon compresstis, 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 (fig. 15). These teeth Fig. 15. Dental apparatus of Ckilodon 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 (l, fig. 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. 2. Amphi- leptus fasciola. 3. Trachelocerca viridis. 4. Tra- chelocerca biceps. ( After Ehrenberg . ) Muscular system . — In the generality of those 1G POLYGASTRIA. 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 Vorticellinae, (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- verse. 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 system and, organs of sense. — No nervous fibrils have as yet been discovered in any polygastric animalcule, and, in accordance with this acrite condition, no special instru- ments of sensation could, according to all phy- siological analogy, be expected 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, ( Euglena longieaudu and Amblyophys,) Ehrenberg says he saw a “ clear sharply defined ganglion,” (einen hellen, scharf umgrenzten 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 Nas- sula ornalti, (1, fig. 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 the dental cylinder. This spot is composed of a great number of little violet globules of unequal size, or, to speak more correctly, of an aggregation of colourless vesicles filled with a violet-coloured fluid. From this spot a canal may be traced running 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 alimentary 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 aggrega- tion of vesicles situated in the back of 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 w'ere quite transparent and colourless. Ehrenberg believes that the violet liquid, which is of a slightly viscid of almost oily character, possesses some dis- solving power, for he has noticed in the alimentary canal of animalcules which con- tained a large proportion of it, that frag- ments of oscillatori® and other substances taken as food were always discoloured, divided, or decomposed apparently by its action. Reproduction. — Not the least remarkable feature in the history 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 the 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 exuvize 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. Fissipurous 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 in ordinary cases as follows. The body of the parent is seen, on its arrival at maturity, to become in- tersected by a transparent line, which divides it into two equal halves. In a short time this transparent line becomes indented at each ex- tremity, 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, (figs.Yt & 18 ) and at length, 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. Tiie direction of the line of separation varies in different species, and even in individuals of the same species (Jig. 1 7. 4, 5, 6, 7, 8) ; some- times it is transverse, sometimes oblique, and in other cases it traverses the long axis ofthebody, 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 Vorticellae and allied forms supported by rigid or flexible pedicles thefissiparous pro- cess is essentially similar. The adult bell (Jig. 9, a) 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 (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 popliteal 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 inclines 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 63 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 cedematous 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 04 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 an azygos 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 passthrough 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 the 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 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 spreading 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 (afj.6p(pos, shapeless ; |c Sop, 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 fibro- 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 r — Axcyoncellum. — 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 subeorneous sub- stance which 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 (xa\ts, 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. — Bodyan 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 quantity compared with the great number of simple silicious spicula which solidify it. Geodia. — A fleshy body, tuberiform, irre- gular, hollow internally, and formed externally by a sort of crust or envelope pierced with a great number of pores, and containing a group of oscules or larger pores placed in a little subcircular space. Siphonia. — Body polymorphous, free or fixed, composed of dense fibres, forming two sorts of canals, some larger and 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 cylindrical, 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 lacuna? ; 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. * History of British Sponges and Litliophytes, by a, Tethea Cranium of the natural size; b, section George Johnston, M. D., Edinburgh, 1842. of the same. {After Johnston ) VOL. IV. F 6G 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 ( Spongia ), 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 this 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 proved by Mr. Bovver- bank * and others, the horny fibres being, in fact, solid and imperforate. In a second group of Sponges, called Halichondria silex ; xov^Pos , 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 sile.r, 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-like crystals {fig. 70) ; nor does any Fig. 70. A minute film of the rind 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. f A third group of Sponges, designated by Blainville, Calcespongia, 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- logical 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. J “ 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, Comp. Anat. p. 5. f British Sponges, p. 89. j Johnston, loc. cit. § Edin. Phil. Joum., xiv. p. 184. PORIFERA. G7 Fig. 71. a, c, d, Spicula of Tethea Cranium ; d, three forked spicula; c, fusiform spicula; a, cuticular spicula; b, spicula 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 spicula 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 spicula 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 of this fluid varies according to the species. In some, it is copious even to nauseousness, but in the compact Halichondriae, 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- tularite ; 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. Living Papillaris, showing the jets of water emitted from the osctila. ( 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. ■j- Hist. Nat. du Litt. de la France, vel. i. p. 78. F 2 Johnston, loc, cit. 68 PORIFERA. sented: — “ On moving the watch-glass, so as to bring one of the apertures on the side of the sponge fully into view, I beheld, for the first time, the splendid 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 beauty and novelty of such a scene in the animal kingdom, long arrested my atten- tion ; but after twenty -five minutes of constant observation I was obliged to withdraw my eye, from fatigue, 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 appeared 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 great 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 artificial canal thus formed, which con- tinued even after 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 small 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 oiifices, 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 microscopes, 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 easdy 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 f, A single observation is sufficient to convince us that this circulation has no- thin" in common with 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 Della 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 difference 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. Pliil. Journal, vol. xiii. p. 104. t Hist, of British Sponges, p. 89. PORIFERA. G9 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 liable 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 then 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 osculutn. 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 * “ When we cut a thin piece of the surface of a living sponge, and look down through one of its pores with the reflecting microscope, we perceive, immediately beneath the projecting spicuia which defend the pore, a very delicate network of gelati- nous threads thrown 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 live or six threads which pass in from 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- tecting spicuia 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. Phil. 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 from the rock the oscula do not rise beyond the surface, because 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 effluent cur- rents. If the texture be loose and fibrous it yields easily, and the oscula are level, or nearly sot if more compact the skin is pushed be- yond the surface into a papillary eminence ; and if too firm and dense to yield to the pres- sure behind, they fall into a level condition. 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 upon 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 spongeby 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 spicuia, along which they are placed. No part in the organization of a sponge is more constant and obvious than these granular transparent bodies, lining the interior of every canal from the pores 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 v 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 difference 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, like 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.”* Gemmules. — Mr. Bowerbank has given the following description of the gemmules of Halichondria 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 5X-, til, 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 papillae, 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, when 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. vol. ii. p. 128, &e. and Edin. New Phil. Joum. 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 bv 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 °f an inch, or about equivalent to the diameter of a disc of human blood, and their average thickness the -rsbns of an inch, so that they are of exceed- ing minuteness as compared with those found in other parts of the same sponge. The propagation 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 Scleroderma, and he may remind us that, like the sporules of sponges, the sporules of fungi are equally locomotive. The Chaos fungorum of Linnaeus is thus described : — “ Habitat uti semen Ly- coperdi, Agarici, Boleti, Mucores, reliquorum- qne fungorum, in sua matre usque dum disper- gatur et in aqua exclusum vivit et moritur, demuin figitur, et in fungos excrescit. Zoophy- torum metaphorphosis e Vegetabiliin Animale fungorum, itaque contrario exAnimali in Vege- tabile.” — Syst. p. 1326. The admissibility of sponges into the animal series is, indeed, extremely problematical, and we 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. ( 7'. Rymer 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 a new 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 reality 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 which, either pro- duced by 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 material. 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 inferior 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< PRODUCTS, ADVENTITIOUS. 72 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 Sub-Class I. ( Saline .) Produced by prcT cipitation from secreted fluids. Sub-Class II. ( A nimalized. ) Produced by exudation from the vessels. Sub-Class I. Products possessed of a dependent ex- istence and derived from a Blastema. Blastemal Formations. Sub-Class II. Products possessed of independent ex- istence and derived from a Germ. Germ- Formations or Parasites. Class I.— Non-Plastic Products or PRECIPITATES. § I- Particles. § H. Masses. C A. Calculi. I B. Concretions. I § I. Protein-Compounds. (certain forms of the). 5 11. Fat. § III. Sugar. Class II. — Plastic Products or FORMATIONS. Order I. Derived from a blastema which generates cells defi- cient in vegetative faculty and in per- manency. Deposits. Order II. Derived from a blastema which generates cells pos- sessed of vegetative faculty, hut defi- cient in permanency. Growths. Order III. Derived from a blastema which generates cells defi- cient in vegetative faculty, but pos- sessed of per- manency. . Pseudo - Tissues . § I. Typhous Deposit. § II. Tuberculous ,, $ III. Purulent „ $ IV. Melanie ,, § V. Diptheritic ,, 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. Order I. Animal. Order II. Vegetable. f Entozoa. X Epizoa. C Entophvta. X Epiphyta. f Ha?matoma. I Sarcoma. Of Protein- basis. < Cystoma. i Angeiectoma. [.Melanoma ? ? r Lipoma. 4 Steatoma. C Cholesteatoma, r Fibroma. 4 Enchondroma. C Osteoma. Of Fat-basis. Of Gelatin-basis. Of undetermined basis. Of Protein-basis. [ Colloma. - Carcinoma. j Induration-matter. f Epithelium. Extra- Vascular. 4 Nail ; Hair. C Cartilage. C Cellular; Serous. ) Fibrous : Elastic. Simple- Vascular. ■! 0sseous; C Nervous. pBloodvessel ; Erectile tissue. Lymph -vessel** Fibro and Spongy Cartilage. Compound- Vascular assu in both lungs. When of recent origin they contain pus and softened tubercle, with or without fcetor, 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 wdthin them ; and still more rarely portions of pulmonary substance, either gangrenous J 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 event 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 fistulas ; 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 possibility would be rash) that evidence has ever yet been furnished of its actual occurrence. § * Univ. Coll. Museum. f Louis. j 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 with 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 circum- stances a cure of phthisis would have been accom- plished. 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 sitigle 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, inline, their struc- tural analogy to fistulas in other parts of the body, form so many a priori arguments against the possibility of cicatrization. Laennec saw their force ; but certain observed facts led him to disregard them, and admit the reality of partied 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. (j6.) In the upper part, especially, of the upper lobes, Laennec frequently saw bands 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 obliterated in the exact site, of those bands or 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 M. Louis has anticipated, hut not, as we think, 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. 110 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 progress of contraction during life would frequently occur, whereas it has certainly never yet occurred to ourselves, nor (so far as we are aware) as matter 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. (1.) 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-pul- monary 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. 1. Pleurisy occurs, local or general, with or without liquid effusion. 2. The resulting plastic exudation penetrates or not into sulci on the pulmonary surface formed by creas- ing ; these sulci are deeper if liquid effusion 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-vellow or greenish colour, and homogeneous aspect ; of faint, pe- culiar smell, when warm ; inodorous, when cold ; of creamy consistence ; anti of sweetish, or sometimes saltish, taste. PRODUCTS, ADVENTITIOUS. 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 liquor 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-gVo °f an inch, — averaging about the -iroVo' Its 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 full)' 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 lie 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, — differences depending on variation of the focus of the microscope. The surface of the nucleus is very finely granular ; its diameter varies from the •g-sVB- to the g-j- of an 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. 6) are figured nuclei visible without the aid of acetic acid. Ill (2.) Under the name of pyoid, 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, resembling 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 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 tether, 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 TsVo t0 ttVo °f an inch in diameter (fig. Fig. 92. Compound granule-corpuscles (magnified 400 diams.). a, in the natural state, diam. = to of an inch ; b, corpuscle about to undergo rupture, the involucrum being more transparent, and the gra- nules larger, darker, and more prominent ; c, a cor- puscle treated with dilute acetic acid, the involucrum being rendered transparent, and several nuclei ap- pearing in its interior. 92) ; and composed essentially of granules and an involucrum. The involucrum is not dissolved by water, and smply 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 involucrum. 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 puris. 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 Psoas Pus from a Mammary Abscess. Abscess. Water 894.4 885.2 879.4 Fatty Matter Cholesterin 17.51 5.4 j 28.8 26.5 M ucus 11.2 6.1 Albumen Lactates, carbon- 68.5 63.7 83.6 ates, sulphates, and phosphates of soda, potash, and lime - 9.7 13.5 8.9 Iron - - - A trace. Loss - 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 pyin, by Giiterbock : 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 f , 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 tempore ) to be tritoxide of protein. Glutin 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 Giiterbock, 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-wall 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 (earlier if it be alkaline), and eventually 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 ik 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. •j- Physiological and Pathological Researches. j Annalen der Phannacie. 113 PRODUCTS, ADVENTITIOUS. varying degrees of dilution of the acid. That the involucrum 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 three 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, by 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 purium by Koch, purulina 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 its 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 corpuscles, and especially the nuclei, attract the iodine from the fluid in which they swim ; for, while they darken, this fluid loses its yellow-brown colour. t De puris natura atque formatione. (Berol.) J Medicin. Vierteljarhschrift von Roser and Wun- derlich, 1842, S. 247. The same writers regard the molecular granules of pus as composed of yet ano- ther variety of protein-compound, resembling 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 water than healthy, and a 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 accidentally 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 inflamma- 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 of 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 well as to extravasation) may, perhaps, be referred the occasional appearance of a little iron among the elements of pus. Fat is much more abundant in pus than in blood ; the high ratio of cholesterin in the former (as ascertained by V alentin *, 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 flesh placed in fresh pus underwent gradual dimi- nution of weight, and eventually solution, without any evidence of putrefaction being manifested. Ultimately, pus does putrefy however ; the occurrence of the change being much hastened by the presence of blood, mucus, or other organic fluids. Acidity', as already hinted, is one of the earliest signs of the change. * In one of Valentin’s Analyses (Kepertorium S. 307, 1838) the proportion of cholesterin is so high as 11.86 per 1000. f Gazette Mtidicale de Paris, 1844. r i PRODUCTS, ADVENTITIOUS. 1 14 The various appearances of pus have given 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 inoculable , — 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-inoculability , 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 fibrin, and fluid holding epithe- lium in suspension. The distinctive characters most to be relied on are as follow : (a) Mucus. (I.) 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 with 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 slimy and more con- sistent. (3.) Pus forms a ropy mass with the caustic alkalies, or with their carbonates. (B. Babington.) Mucus, on the contrary', 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 syphilitic 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 (Notizen, 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, No. 28. p. 88) as a species of acarus. 1 his matter requires revision ; it has even been sug- gested that Donne and his followers have mistaken ciliated epithelium-scales (to which indeed the figure ot the former hears much resemblance) for animal- 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, which remains clear and becomes colourless on the addition of water. (Brett and Bird.) (7.) According to Prettss, 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 iridescent 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 surface, 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 Fibr'm.— 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. Gulliver-)- gave support to this notion by pointing out the following peculiarities, distinguishing the substance in question from pus : I . 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 puris is a more elaborate process. + Med. Chir. Trans, vol. xxii. PRODUCTS, ADVENTITIOUS. 115 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, iu part, of pus. We have more than once discovered fully-formed and well-conditioned pus-corpuscles in such co- agula, 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 the present, perhaps, to refrain from adopting any one of them. (c.) Epithelial fluid. — 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 kidney. 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 saline 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 described (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. We 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, without 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 l' In- flammation, SfC.) 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 pus- corpuscles, the theory manifestly involves an impossibility, as the structure of the walls of the capillary vessels is too close to permit the passage of bodies of such dimensions. * Op. Cit. p. 4. I 2 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(J756), Morgan (1 703), Brugmans ( 1785), and John Hunter. The direct microscopical evidence, upon which it has been finally established, was ori- ginally and mainly supplied 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.J 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 Me'd. Juin, 1836. t The first change discoverable under the micro- scope seems to be loss of elasticity. t Prussic acid, according to Dumas. (Comptes Rendus de l’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 muriate 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 — unassociated , 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 water (which we have used) does not actually destroy the colour, but diminishes its intensity greatly. PRODUCTS. ADVENTITIOUS. 117 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 latter 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 cell-pigment, 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 ; (b.) Introduction of black-coloured substances from without. (a.) Alteration of hoematosine. — 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 interfering 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. That 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. j- 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 safety-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 of 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-pigment 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. 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 include under the title Diphtheritic’ (A ctydepri, 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 ( Muguet of the French). — The matter of white thrush forms on the mucous membrane ot the mouth, fauces, aeso- 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 looks 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 appeared to us from numerous observations, that it is less prone to become entophytic. ( h .) 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 and the similar produce of mucous membrane. Entophytic formation occurs here. Order IL — 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 inoculation 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-like 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 cases (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 Tooo^th °f 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 ToVo an) When not absorbed, blood either (1) ex- cites inflammation and its consequences ; or (2) remains stationary in a fluid condition; or (3) assumes the characters of dark grumous semi- coagula ; or (4) undergoing inspissation from deprivation of its watery parts, a firm co- agulum, growing daily more solid, remains be- hind : in this last instance we have a coloured haematoma. A haematoma is then a fibrinous mass, coloured or not, arising from haemorrhage. Before us (Univ. Coll. Mus.) lies a colour- less haematoma of the spinal meninges in the cervical region, the result of a blow. Its size is that of a walnut ; it is of pale straw-colour, homogeneous on superficial view, but finely granular when closely inspected. Haematoma may, however, be coarsely loculated ; the walls of the loculi being solid, the contents more or less fluid, or gelatiniform-looking. Such tumours (while unchanged in characters) exhibit microscopically the qualities of fibrin, — fibrils gelatinizing with acetic acid, — amor- phous fragments, granules, and molecules. Their colour varies ; it may be of deep yellow, somewhat buff', tint,— and commonly is so, in the spleen and kidney, for instance. Their chemical reactions are those of fibrin. The surface of a haematoma is smooth ; a coating of epithelial structure, rapidly form- 126 PRODUCTS, ADVENTITIOUS. ing, gives it this character. A haematoma is rarely encysted ; for though nothing is more common than the formation of a cyst round effused blood (apoplectic cyst) as a general fact, yet this process is rarely wit- nessed, where the progress of absorption has been of the kind to produce a haematoma. Haematomata may probably form wherever blood, thrown out from the vessels, is re- tained. Thus (1) they are seen in the serous cavities, — as the peritonaeum and pleura, where they have more than once been found in the stages of transition ; and in synovial cavities, where, as John Hunter long since maintained, they frequently form the so-called “ loose car- tilages” of joints. (2) Amid membranous structures, — as for instance, under the choroid coat, where they have been frequently mis- taken for carcinoma ; into the great cavity of the arachnoid (Univ. Coll. Mus.) — a not un- common seat ; between the arachnoid and dura mater of the skull, where, we feel posi- tive, they have occasionally been the origin of minute fibrous tumours ; under the mucous lining of the uterus, where a similar destiny sometimes awaits them; under the periosteum, either when the blood has flown through the influence of external injury, or through the influence of causes, partly traumatic, partly spontaneous, as in that singular affection of new-born infants — cephalhematoma. — (3) In parenchymatous organs, as the brain, the spleen, the kidneys, the lung (in all of which we have repeatedly seen them), and more rarely in the mamma, where they have often, clin- ically, played the part of cancers. — (I) In the cellulo-muscular structures of the limbs, as the result of contusions or spontaneous haemorrhage. — (5) In the proper substance of certain new products, especially encephaloid cancers. — (6) In cavities accidentally formed in the tissues, as in tuberculous cavities in the lung. (Univ. Coll. Mus.) Various changes of deep interest may occur within the substance of a haematoma. Unsup- plied with vessels, as it commonly is, it cannot be the seat of interstitial haemorrhage ; but blood may nevertheless infiltrate its substance derived from the ruptured vessels of surround- ing textures, — just as extra-vascular tissues may become infiltrated with exudation-matter produced by inflammation, not in them, but be- side them* ‘Saline precipitation is a common occurrence ; such is often the origin of ossiform particles or masses in the brain ; of similar masses in advanced cephalhaematoma j- ; and such (as elsewhere shown by us) is almost in- variably the source of free calcareous and ossi- form products in cancer : the changes con- cerned in the production of a phlebolith are one by one gone through. That melanic pigment may form in haematomata appears extremely probable, from certain observations which we made several years ago on some specimens of melanic tumour ; full reference to these will be * A remarkable example of hremorrliage into a haematoma of the brain lately occurred in our wards in University College Hospital. f See this word, Cyclopaedia of Surgery, vol. i. found in the section on Melanoma. We have in a previous section spoken of the doubt still hanging over the question of the possible evo- lution of simple effused blood into Forma- tions of definite structural characters. The question appears to be all but absolutely decided in the affirmative by a tumour now before us (Univ. Coll. Mus.), in the substance of which the transition from the characters of haematoma to those of fibrous tumour, is per- fectly traceable in point of colour, consistence, and textural arrangement. Bone-formation may take place from blood effused in localities where a tendency to such formation naturally exists, and where formative life is active. Thus, in the instance of sub-pericranial ce- phalhacmatoma, the smooth gelatinous-looking membrane, which invests the blood, may be- come so perfectly ossified, that it has, in this state, been evidently mistaken by some ob- servers for the outer table of the bone, and a figment, in the shape of interstitial or diploic cephalhasmatoma, invented to meet the dif- ficulty. Even in the centre of the fibrinous residue of this effused blood actual bone has sometimes been seen. Concerning the vascularization of blood in substance we have already given our opinion. Haematomata in the brain have been found dis- tinctly vascularized in cases where there was no evidence that plastic lymph had been added to the extravasated blood ; and M. Louis’ description, already referred to, of a vascu- larized coagulum in a tuberculous excavation of the lung is peculiarly satisfactory. Blood retained in its proper canals may coagulate and undergo various changes. In the arteries, cellulo-ftbrous evolution and cal- cification occur in stagnating blood without the intervention of an inflammatory process : in the veins we have seen vascularized coagula injected ; and the formation of phleboliths and arteroliths illustrates saline precipitation. Vascularized coagula in the heart have been described by Rigacci, Burns, Bouillaud, and others. $ 2. SARCOMA. Simple sarcoma (crap£, flesh), or cellulo- vascular growth, presents itself as a mass of variable dimensions, — those of a hazel-nut and of a cocoa-nut are the extremes we have seen. Of oval or, less commonly, spherical outline, its surface may be even and tole- rably smooth, or nodulated (U. C. Mus.). Sarcoma is particularly elastic ; varies much in consistence and density ; breaks sharply under the nail, in the direction of its fibres ; is rather crisp than tough, unless in the site of its cellulo-fibrous locular walls ; exhibits on section a tolerably smooth, glossy, semi- transparent surface, such inequalities as exist depending upon the unequal elasticity of its containing and contained elements ; is free from greasiness, either to the look or feel ; is usually of pale yellowish or buff colour in the main, presenting here and there reddish or more rarely lilac-tinted spots, or stria?, or PRODUCTS, ADVENTITIOUS. 127 (it may be) a more or less uniform red hue ; and yields on pressure a small quantity of slightly glutinous, thin, yellowish, transparent fluid. The vessels of sarcoma may be pretty equally distributed through its substance, or set in a sort of patch-work. These growths are essentially disposed to become encysted. Their cyst, vascular and cellular like themselves, may be fibrous in part, and is formed both of natural cellular tissue condensed, and of exudation-matter solidified. This secondary or pseudo-cyst adheres closely to their surface, and appears continuous with the cellular and thin, or fibrous, thick, and opaquely white, membranous septa of the growth. Molecular matter, granules, spherical, oval, and caudate cells, and fibres form the ulti- mate constituents of sarcoma. Its spherical cell seems to us identical with the common inflammatory exudation cell. (See Pseudo- Tissues.) The oval cell, of larger size (mea- suring .00073 of an English inch and upwards, according to some estimates by Muller), is provided with a dark, well defined, but small nucleus : such cells are sometimes enclosed within a mother cell-wall of proportional dimensions, and afford clear evidence of endo- genous procreation. Slightly elongated at opposite ends, as they sometimes are, they eventually pass into the state of caudate or spindle-shaped cell {fig. 93). Such cau- Fig. 93. Caudate cells from an albuminous sarcoma of the conjunctiva. (After JHiiller.') date cells are either arranged in linear juxta- position, as above ; or they are scattered loosely through the mass. They are not plainly nucleated, as a general rule ; but acetic acid brings out a parietal nucleus. They seem to pass by an easy transition into fibres ; and eventually these fibres acquire for the greater part the characters of those of cel- lular tissue, but occasionally of fibrous, and yet more rarely (we have seen this) of elastic texture. The molecular and granular matter of sarcoma is probably in part fatty ; but oil- globules are of rare occurrence. Sarcoma is mainly composed of albumen ; but (especially when a c\st with thickened processes exists) will yield a small quantity of gelatin by boiling. There are probably few sites in which sar- coma does not form. We have seen it in the cellular tissue under the lower jaw ; in the substance of both maxillae (whence it has fre- quently been removed with successful results); under the periosteum of the long bones, or (more rarely) in the actual substance of these; in the mamma ; in the eye ; in connection with fibrous textures, as the dura mater, &c. Haemorrhage, calcification, and suppuration occur in sarcoma ; the latter with great rarity. We have never seen cancer within the area of a sarcoma. Condensation and detrusion of surrounding parts are mechanically caused by this growth ; it has no intrinsic tendency to affect those parts otherwise, though inflammatory changes may, from over distention, be induced among them. § 3. CYSTOMA. See Pseudo-Tissues ; Serous. $ 4. ANGEIECTOMA. Masses of variable size composed of dilated and elongated vessels may be described under the name of angeiectoma (avyuov ekt uvw). They are rare productions, and seem essen- tially produced by dilated hypertrophy of the small vessels, venous or arterial. A tumour of this kind has been figured by Dr. Carswell, (Fascic. Melanoma, pi. ii. fig. 2). It was sunk into the substance of the brain, but evidently in connection with the pia- mater. “ The bloodvessels of the pia-mater passed into it, and constituted by far the greater part of the tumour. They became tortuous in its substance ; some of them, being nearly a line in diameter, were reflected back- wards at their extremities in the form of irre- gular intertwined bundles, towards which two or three small arteries, coming from the pia- mater, were seen to distribute themselves.” Lobstein (Anat. Path. t. i. p. 461) describes a similar mass formed of a venous plexus. In both these cases the veins contained, and were bathed in, melanic liquid. Dr. Warren (On Tumours) figures and describes a case of con- genital tumour composed of greatly dilated and knotty veins seated in the neck. There is a species of epulis which appears to be composed of dilated and hypertrophous arteries. Cruveilhier (Anat. Pathol, livrais. 33.) describes certain tumours on the surface of the skull, pulsatile, erectile, and the seat of blowing arterial murmur, which had eroded the bone ; there were similar forma- tions in the external'soft parts; they were composed of dilated “ arterial capillaries.” A man was admitted some years ago into Univ. College Hospital (Mus. Model 2854), under Mr. Liston, having a series of pale red, knotty tuberosities, extending from the left orbit to the occiput, pulsatile, erectile, and the seat of blowing murmur at a particular point. Death ensuing, Mr. Marshall examined the larger of the series, and found that it con- sisted in the main of dilated and tortuous arteries, with intervening fibrous tissue and granular fat ; large straight veins existed, and one or two of these uniting at obtuse angles, passed between (but did not communi- cate with) the arterial branches at the site of the blowing murmur. No true erectile struc- ture was to be seen. Tumours of this kind (such are many naevi, naevi verrucosi, and aneurisms by anastomo- sis), because physiologically 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. ( U. C. Musi) 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 trabeculae 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 trabeculae 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 rapidlyregenerated if imperfectly removed. Particularly when connected with the skin, erectile structures may become the seat of cancerous formation. Erectile Growths 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. Liston (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. MELANOMA. Melanie 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 (ards each other in front, they bound two sides of a small triangular portion of the gland ; this is the under surface of the third lobe, on either side of which a vas ej aculatorium takes its course. The prostate is surrounded by a dense capsule derived from the vesical fascia; this gives it a complete investment, and adheres so firmly to the tissue of the gland as to be separated from it with great difficulty. It is divisible into two layers,, between which the prostatic plexus of veins runs. The gland itself is of a lightish brown colour, of a fleshy feel, and when cut it offers the resistance ot soft cartilage : it is one of the firmest glands in the body. It is principally formed of two lateral lobes, a right and a left, of equal size in the healthy condition, of an ovoid shape, with their long axes from before backwards ; they diverge from each other behind, leaving an in- terval between them, already mentioned; the lateral lobes are connected together beneath the urethra by an isthmus of variable depth and breadth. Between the two lateral lobes, which make up the bulk of the gland, we find the middle or third lobe. The name of Sir Everard Home is usually associated with the description of this lobe. Although not the dis-. coverer of it, he gave the first full description of it. Mr. (now Sir Benjamin) Brodie made dissections of it under Home’s direction ; in the first subject in which it was examined, it appeared as a distinct gland, resembling Cow- per’s gland in size and shape ; but in the ex-, animation of this body in five different subjects, the appearance was not the same in any two of them. The following is the account given by Home of what he considers the most natural condition of this part of the prostate : — “ On turning off the vasa deferentia and vesiculae seminales, exactly in the middle of the sulcus, between the two lateral portions of the prostate gland, there was a round, pro- J48 PROSTATE GLAND. minent body, the base of which adhered to the coats of the bladder. It was imbedded not only between the vasa deferentia and the blad- der, but also in some measure between the lateral portions of the prostate gland and the bladder, since they were in part spread over it, so as to prevent its circumference from being seen, and they adhered so closely as to require dissection to remove them ; nor could this be done beyond a certain extent, after which the same substance was continued from the one to the other. This proved to be a lobe of the prostate gland ; its middle had a rounded form, united to the gland at the base next the bladder, but rendered a separate lobe by two fissures on its opposite surface. Its ducts passed directly through the coats of the bladder on which it lay, and opened immedi- ately behind the veru montanum.” Fig. 102. A posterior view o f the bladder and prostate, with third lobe ; the vasa ejaculatoria and vesiculce are thrown forwards. ( From Sir E. Home.) a, ureter ; b , bladder ; c, third lobe of prostate ; d, vas ejaculatorium, turned forwards ; e, vesicula seminalis ; f, vas defei'ens. It is well known that Hunter was aware of the existence of this lobe as a natural consti- tuent of the prostate, for he says, “ A small portion of it (the prostate) which lies behind the very beginning of the urethra, swells for- ward like a point, as it were, into the blad- der; acting like a valve to the mouth of the urethra, which can be seen even when the swelling is not considerable, by looking on the mouth of the urethra, from the cavity of the bladder in the dead body. It sometimes in- ci eases so much, as to form a tumor project- 's into the cavity of the bladder some inches. Hunter has given an accurate draw- ing of the middle lobe of the prostate. In the normal state it represents a simple elevation of glandular structure beneath the uvula vesicas, between the two lateral lobes at the back part, and connected laterally with them ; but it varies materially in size and consistence in different subjects. 1 have no doubt that in some cases it is wanting altogether, in others it is of small size; and in many, where it is well developed, it is as firm and consistent as the other parts of the prostate. In one ex- ample which I examined, it was much firmer than the lateral lobes, and of a much lighter colour; indeed, so distinct did it appear that I really doubted whether it belonged to the prostate. I applied a microscopical test, and found its ducts charged with similar concre- tions to what have been so frequently found in other parts of the gland ; this proved to me that it was a part of the gland itself. The best method of viewing the third lobe is to make a vertical section from before backwards through it, and to carry the incision directly through the veru montanum, sinus pocularis, urethra, and inferior part or isthmus of the prostate, the divided third lobe is thus brought into view, as well as the ejaculatory duct of one side, passing between it and the lateral lobe. The sinus pocularis runs beneath it (see fig. 10J). The urethra traverses the prostate from be- hind forwards, and is completely surrounded by it. Amussat doubted this fact, and thought that only three fourths of the canal were en- circled by the prostate, and that the remain- ing fourth (the anterior) was covered by a cellular or muscular medium, extending from one lobe to the other. This is undoubtedly incorrect as a general rule, for 1 have examined with the microscope that portion of the gland placed over the upper surface of the urethra, and found it identical in structure with the remainder of the organ. The urethra in pass- ing through the prostate is dilated into a con- siderable sinus, and presents in front a trian- gular opening if a transverse section be made. It is not exactly in the centre, being nearer the anterior than the posterior surface ; it is generally said to be about two lines distant from the former, and four from the latter, and seven from the lateral surface of the gland. It varies frequently in this respect in a marked degree. When the third lobe is small and flat it is much nearer the posterior surface than the anterior ; and this is the case where the isthmus or medium of connection beneath, is thin, a condition not very uncommon. The prostatic portion of the urethra is about fifteen lines in length, and is wider in the middle than at either extremity ; it con- tains within it the veru montanum or caput gallinaginis, which runs along it, forming a conical elevation, and dividing it into two equal portions. Over the urethral surface of the third or middle lobe of the prostate, the mucous membrane is raised up so as in some subjects to form a remarkable elevation, lying trans- versely at the beginning of the urethra ; this PROSTATE GLAND. 149 is especially seen in old subjects : it corre- sponds with the anterior extremity of the Fig. 103. Front view of the bladder and prostate, a, bladder ; b, ureters ; c, uvula vesicas ; d, prostate gland ; e, openings of prostatic ducts ; f a probe passed into the sinus pocularis ; g, g, bristles in vasa ejaculatoriuni ; li, membraneous portion of urethra. trigonum vesicce, and is known by the names of the uvula vesicce, luette vesicate, valvula pylorica of Amussat. In the healthy state of the bladder and prostate, this elevation is frequently scarcely perceptible, unless the bladder is much contracted ; but it is subject to considerable increase in size, and is gene- rally involved in those cases of enlarged pros- tate which are of such frequent occurrence in the old person, and where the third lobe is the seat of hypertrophy, Mercier describes this vesico-urethral valve as a semicircular fold, raised suddenly at a right angle from the posterior surface of the neck of the bladder, and composed of a tissue somewhat resem- bling muscle ; and Mr. Guthrie, in his lectures delivered at the College of Surgeons in the year 1830,- directed attention to it as fre- quently the seat of disease totally independent of any enlargement of the third lobe of the prostate ; but to this I shall again direct attention when the morbid anatomy of the prostate is under consideration. Intimate Structure. — The prostate comes under that division of the glandular system, inappropriately termed conglomerate. Muller places it in his fourth order of glands — “ glan- dules ex ce/lulorum contextu spongioso composites, mediis cellulis in ductus excretorios hiantibus, sine lobulorum divisione composita.” It is ar- ranged by Cuvier under the head of supple- mentary glands of the male organs of genera- tion. The external covering of the gland, de- rived, as already described, from the vesical fascia, having been removed, we come to a deeper layer, which closely surrounds the glandular tissue ; it is most intimately con- nected with it, so as to be detached with the greatest possible difficulty, and can evi- dently be shown to send processes into the gland, which are probably continuous with the fibrous tissue between the follicles. On the surface of this the lymphatics of the gland are seen to ramify : this is best shown after pre- vious immersion in water. If a simple section is made, the gland presents a spongy cellular aspect, and an opaque fluid oozes out from the cut surface ; but its intimate structure can only be made out by microscopical examin- ation of thin sections, or by injections with mercury or coloured size, or by inflation ; the outline of its follicles may, however, be seen by a minute injection of its blood vessels, which ramify in a delicate plexiform manner on their surface. It is not a gland of much complexity of structure or arrangement. Briefly, it may be said to be composed of minute terminal follicles, opening into canals or tubes, which unite together to form ducts, which open in an oblique manner on the pros- tatic portion of the urethra. The orifices of the prostatic ducts are situated principally close to and around the most elevated portion of the veru montanum, in the form of a cres- cent, the larger ducts on the side* and the smaller on the posterior aspect of this body If a longitudinal, vertical section is made, many of the ducts of the prostate are seen passing upwards, towards the under part of the veru montanum, in a straight direction ; the interior of some of them being slit open in the section, whilst others pass obliquely be- neath the mucous membrane for some dis- tance prior to their termination. They vary in number from ten to fourteen, but as many as thirty have been seen. Their diameter ranges from one-sixth to one-fourth of a line. It sometimes happens that two or more ducts unite, and open by one common orifice, large enough to admit the end of a small probe. To unravel the structure of the gland, it is requisite to inject the ducts separately, as the follicles to which they lead have no commu- nication with each other, as the representation given by Muller would lead one to imagine; each duct will be found to give off tubes, which passing in a straight direction, separate gradually from each other, and terminate in minute cells or follicles, which, according to Weber, range from one-sixteenth to one- twelfth of a line in diameter. Muller says that the larger cells are visible to the naked eye, and that with a simple microscope the smaller cells, situated within the larger, and formed of an exceedingly delicate membrane L 3 150 PROSTATE GLAND. can be seen ; the cellular structure is rendered perceptible by inflation from the ducts. Mr. John Quekett has injected with coloured size, and examined the tubes and follicles of the prostate with the microscope, and represents the latter as varying in size in different parts of the gland ; he thinks that one-hundredth of an inch is their average diameter, and has de- lineated them as is shown in Jig. 104. Henle Fig. 104. has found them to be lined by a delicate pave- ment epithelium, and at the commencement of the duct he has seen a cylindrical epithe- lium. Mr. Quekett has traced an intermediate cellular or fibrous tissue, filling up the spaces between the follicles or lobules, and connect- ing them together. According to Dr. C. H. Jones, “ this principally consists of the white fibrous element, but also contains numerous bands, resembling closely those of organic muscle.”* The latter anatomist thinks that the enlargement of the gland in hypertrophy of the prostate, is due to an increase in this tissue: he regards the prostate as an assem- blage of secerning follicles rather than as a really conglomerate gland. The arteries of the prostate are usually derived from the vesical and haemorrhoidal branches of the internal pudic, and from the middle haemorrhoidal of the internal iliac, which, entering the gland on either side be- neath its capsule, are distributed in the form of a network on the parietes of its tubes and follicles; the veins terminate in the vesical and haemorrhoidal veins : its nerves, which are ex- tremely small, are branches of the hypogastric plexus of the great sympathetic. The lym- phatics consist of a superficial and deep set, and pass into the hypogastric ganglia. It happens occasionally that an artery of consi- derable magnitude runs on either side of the prostate, from the internal iliac, and becomes the artery of the bulb of the urethra. This variety has been seen by Haller, Burns, and Barclay. I have witnessed a similar distri- bution myself. Dr. Monro met with a case, in which an irregular vessel came from the internal iliac, passed along the lateral and in- ferior surface of the bladder, pierced the ilio- vesical fascia, ran along the lateral lobe of the prostate, and divided into three branches, one to the dorsum, one to the crus penis, and another to the bulb. Other varieties in the course and distribution of the branches of the internal iliac, involving the prostate, have been occasionally met with, and I allude to them here as points of great interest in respect to the surgical anatomy of this body. Liquor Prostaticus. — It is the office of the prostate to eliminate from the blood sent into its arteries a fluid called the liquor prostati- cus. This has been examined microscopically; but in consequence of the difficulty in obtain- ing it in any large quantity, it has not hitherto been made the subject of chemical analysis. This fluid can be obtained after death by squeezing the gland, when it oozes through the orifices of the ducts around the veru ntontanum. It usually presents a turbid ap- pearance, is of a thin milky aspect, and is somewhat unctuous to the feel. Haller found it in many cases coagulable by the addition of alcohol : it contains, according to Krause, muddy flakes, or globules, filled with minute granules, varying from to of a line in diameter. Prevost and Dumas examined the liquor prostaticus of the dog, cat, hedgehog, and rabbit : they found it to contain globules like milk-globules. Cuvier remarked in the fluid of the hedgehog, numerous ovoid and spherical vesicles, others oblong and conical in shape : many of the vesicles presented a stellate aspect, and contained a central nu- cleus. I have carefully examined, in many cases, the prostatic secretion of the human subject, in as fresh a state as I could possibly procure it. I have found it of a milky aspect, like a very weak mixture of milk with water. In some cases, I have seen it of a consistence more resembling cream. I consider the for- mer state to represent the healthy fluid. Examined with the microscope, it was found to contain numerous molecules, epithelial cells, both pavement and cylindrical, in va- rious stages of formation, and granular nuclei of about 0 0036 of a line in diameter. In by far the greater number of instances in which I have examined it, I have been rather surprised to find it give feeble but distinct signs of acidity when tested by litmus paper. I thought it not unlikely that the apparent acidity of the prostatic secretion was due to the cadaveric infiltration of urine through the tissue of the gland ; but I adopted every pre- caution, by carefully and repeatedly washing the surface of the bladder and urethra, to ob- viate this source of fallacy, and the result was still the same. I have found a similar reaction in the prostatic secretion of an old man, in w'hom the gland was greatly hypertrophied ; and where the ducts and follicles W'ere dis- tended with an opaque creamy-looking fluid, such as is often seen after death. The ap- pearance of the liquor prostaticus may be, and probably is, very different after death to what it is during life. There is every reason to believe that it is secreted more clear and transparent, and it most likely owes much of its turbid appearance to the admixture of a large number of minute epithelial cells. I regret that I have nothing to offer as to its chemical constituents, as it is not possible to collect more than two or three drops at a time, a quantity too small to submit to che- mical investigation. That the acidity of the Medical Gazette, Aug, 20. 1847. PROSTATE GLAND. 151 liquor prostaticus is not incompatible with the existence of calculous concretions of the phosphatic species in the follicles of the gland, I have proved by repeated examination. Utrieulus prostaticus. Vesicula spermatica spuria. Vesica prostatica. Sinus pocularis. — At the anterior part of the most elevated por- tion of the veru montanum, we find an open- ing in the mesial line one-third or half a line broad, leading backwards to a small bag re- sembling a bottle in figure, of variable length and breadth : it is generally known by the name of the sinus pocularis, but has received Fig. 105. a, bladder ; b, middle lobe of prostate ; c, view of the left side of the utrieulus prostaticus ; d, bristle in left vas ejaculatorium. also the designations here mentioned. In most cases in which I have examined it, it forms a canal, terminating in a blind extremity, and usually is not more than three or four lines long. I have found it an inch in length. The opening, which faces obliquely forwards, will just admit the point of a small catheter or bougie. Some surgical interest is attached to this structure, because it has been stated by writers on urethral diseases that an instru- ment is liable to catch in it when an attempt is made to pass it into the bladder ; but I be- lieve this very rarely happens, as the beak of the catheter is usually kept against the an- terior surface of the urethra, when it is made to traverse the prostatic portion, and it is therefore carried well above this little pouch : if, however, such an accident should be sus- pected to have occurred, a gentle withdrawal of the instrument and depression of the han- dle are quite sufficient to clear the impedi- ment referred to. But much physiological importance attaches to this sinus, for reasons which we shall presently see. Huschke de- scribes it in the following manner : — It com- mences by a narrow portion, resembling a neck, which forms about half its length, be- hind which it swells out into a round mem- branous vesicle or fundus ; between these two portions there is often a constriction. It penetrates the posterior surface of the pros- tate gland, so that the middle lobe is situated in front of its fundus. Its parietes are thinner at the fundus than at the neck, and are usually about one-fourth of a line in thick- ness. On either side a vas ejaculatorium is inclosed within its wall ; so that, in point of fact, these ducts do not penetrate the glan- dular substance of the prostate. Its walls are composed of two layers, an external, fibrous and strong ; an internal, of a mucous charac- ter : the latter is covered by small mucous glands, arranged closely together, with open- ings of about the twenty-fifth of a line in diameter. These glands resemble minute warts, each with a small opening on its apex. They cannot be confounded with the orifices of the prostatic ducts, as these always open external to this pouch, around the veru mon- tanum. About its neck larger glandular open- ings are perceptible. The nature of the se- cretion of these glands is not known. Great physiological interest attaches to the utrieulus, from its having been supposed by anatomists to be the true representative of the uterus. Its homology with this body is evinced by its shape, and position between the two ejaculatory ducts, although the latter do not open into it, as the fallopian tubes do into the uterus ; thus it resembles the latter body by its division into a neck and fundus, by its being surrounded by the prostatic ducts, as the uterus is at its orifice by the follicles there situated, and by the veru montanum forming to its orifice a prolonged inferior labium ; anti if, as some anatomists assert, the ejaculatory ducts occasionally open directly into the pouch, or previously unite together, the parallel is infinitely more perfect. Morgagni has g;ven a description and figure of the utrieulus as he found it in five subjects which he examined. Ackerman also described it, and termed it uterus cystoid.es, and mentions instances described by Petit, Sue, and Maret, where it was an inch in extent. In one case mentioned by himself, it was actually larger than the prostate gland. E. H. Weber pointed out its physiological interest as a rudimentary uterus, and Huschke, has found it filled with a yellowish liquid, in which he distinctly re- cognised portions of cylindrical epithelium.* The best description I can find of this struc- ture, is that by Huschke w ho examined it in the hare. He found it in this animal in the form of a bottle, fifteen lines in length and half an inch in breadth, extending behind the bladder. It commenced by a simple transverse fissure, from a line to a line and a half in breadth, over the veru montanum. It gradually dilated for about half an inch, and becoming contracted, it was again dilated, and terminated in a point rather to the left side. The vasa deferentia were situated by the side of the utrieulus, and gradually ap- proximating, they opened within a line of each other in the utrieulus, at about a line and a half or two lines from its orifice, by two large papillary' openings ; so that when air was injected by one vas deferens, it not only escaped from the opening of the utricu- lus, but filled its cavity, and passed into the other. Huschke supposes that the utrieulus in this animal always contains semen, as the existence of spermatozoa, and the appearance of the fluid indicate. In an anatomical point of view, he does not consider it at all analogous * See note to “ Huschke, in Encyclopedic Anato- mique_traduit de l’Allemaud par A. J. L. Jourdan.” L 4 152 PROSTATE GLAND. to the vesiculae seminales of man ; but in the hare as an uterus for the reception of semen, as the female uterus receives the ovule. A more minute examination of this hag strengthens this conviction. Its orifice is transverse, anil represents an os tincse in the arrangement of its labia ; 2dly, there is an evident distinction in the mucous lining of its neck and fundus, it being arranged in five or six longitudinal folds, so as to form a true arbor vitae, and seems covered with muscular fibres. The following are the deductions of Huschke : — 1st, That the utriculus is a male uterus; 2dly, that it is originally a recep- tacle of seminal fluid ; 3dly, that its develop- ment is in the inverse ratio of the develop- ment of the vesiculae seminales and prostate gland in man ; 4thly, that it is a vestige of a structure existing in the foetus, and in man is really of no use whatever. Cuvier has described a long membranous canal with a spherical extremity, situated be- tween the two vasa deferentia in the solipeds. This long bag opens on to the urethra, in front of the common orifices of the vasa defe- rentia and vesiculae seminales, rather to the left side. A fluid of the consistency of honey can be squeezed out of it. This is evidently the utriculus. In an interesting case of hypospadias, a case peculiarly favourable for the investiga- tion, Professor Theile, of Berne, most care- fully examined the utriculus, and described its anatomical relations. I take the following account of this examination from the first number of the “ British and Foreign Medico- Chirurgical Review:” — “ The scrotum con- tained two testicles ; the vasa deferentia, vesiculae seminales, and prostate gland were present. The latter was fourteen lines long, eight and a- halfthick, and. sixteen broad. Theile found a canal originating in the usual opening on the utriculus, run backwards for an inch and a half, ending in a cul-de-sac four lines in diameter, and placed between the two vasa deferentia; this canal (vesica prostatica), with the exception of its anterior part, did not lie within the prostate, but below or behind this gland. Besides this structure, a small, ovaL, glandular body, five lines long, four broad, and two thick, was found behind, lying between the vesica prostatica and the prostate itself; it did not appear that this substance was continuous with the substance of the prostate, although this continuity might have existed and escaped detection. Examined by the microscope, this body presented an aggrega- tion of cells and vesicles, which were much more easily seen in it than in the proper pros- tate. Theile regards this body, lying closely upon the vesica prostatica, as a middle lobe of the prostate. In order to ascertain the rela- tion of the ductus ejaculatorius with the vesicle, a wax injection was thrown into the lower part of the vas deferens. On a careful examination, it was found that the ejaculatory duct did not open into the utriculus, but was only closely applied to its lateral wall, and then penetrated into the urethra in the usual place.” In this case the membranous portion of the urethra opened into a normal bulbous portion. Professor Theile also gives an account of another case of hypospadias, “ dissected by Fig. 106. the elder Soemmerring, in which the urethra and scrotum were fissured, the testicles re- maining in the abdomen. Between the glands and the anus two openings were found, separated by a partition of about one line in breadth. That next the penis was the orifice of the urethra ; the latter led into a canal, into which a quill could be passed. It was an inch and a half long, and when inflated it was nearly as large as the little finger, and was situated between the bladder and rectum, but nearer to the former. Soemmerring laid open the canal towards the rectum, and it appeared like ‘ an alveus communis,’ into which the vesiculae seminales opened. When quicksil- ver was injected into the vasa deferentia, it ran partly into the vesiculae seminales, but partly into this pouch.” “ The existence in the male of a central sac or canal, occupying precisely the same relation to the orificium urethrae, the bladder, and the rectum, as the vagina in the female, is particularly elucidative ; and, among other facts, for which we are indebted to em- bryological research, further corroborates the conclusion of the most scientific anatomists of the present day, that every variety of so-called hermaphroditical malformation is referrible to an abnormal condition, either of the male or of the female organs, existing singly, and but rarely conjoined in the same individual.” PROSTATE GLAND. With these facts before us, there is no ne- cessity to resort to the mechanical idea of the gradual distension of the prostate gland and vesiculse seminales to account for the existence of a rudimentary uterus in those cases of hermaphrodism where the subject is unquestionably male, with an increase in the development of the utriculus beyond its na- tural condition. I would also venture to suggest, that what Mr. Hunter has delineated as the uterus, in the representation he has given of the dissection “ of Mr. Wright’s free- martin, which are more the parts of a bull than those of a cow,” is really a preter- naturally large utriculus prostaticus. I have given a side view of the interior of the utricu- lus, in a case which I examined myself ; in this instance it extended obliquely down- wards and backwards, beneath the third lobe of the prostate, for the distance of about half an inch, and was slightly enlarged at its fundus. (See fig. 10-1.) The development of the prostate and vesicula prostatica. — There is no department of em- bryological research of higher interest than that relating to the development of the genito-urinary system. A minute inquiry into this subject, and a careful observation of the phenomena attending it, can afford the only means of obtaining a satisfactory clue to the comprehension of that remarkable structure just described. By no other means is it pos- sible to ascertain the natural relation of the utriculus prostaticus. I shall limit the inquiry here to the manner in which the utriculus and prostate gland are supposed to be formed. At an early period of foetal existence the allantoid sac, which was continuous with the urinary bladder, becomes shut off entirely from that viscus, and the only remains of its original communication is the obliterated ura- chus. As the bladder at its inferior fundus communicates with the intestine, thus forming with it one common cavity, it may fairly be said that the human subject really is at this period possessed of a cloaca. In the mammiferous class generally the urinary bladder very soon separates from the intestine, and has a sepa- rate opening externally in front of the anal aperture. There are different opinions as to how this is actually accomplished ; but there is no necessity to discuss the question here. In this separation of the bladder from the rectum, the evidence of the existence of a cloaca disappears, and a cavity, or space, or canal is left common to the bladder and geni- tal organs ; this is termed the sinus uro-geni- talis, or the canalis uro-genitalis. This after- wards, in the male, is represented by the neck of the bladder and beginning of the urethra, and communicates with the external organs. In the monotremata the uro-genital canal is persistent. The sinus uro-genitalis receives the terminations of the excretory ducts of the Woolfian bodies, the ureters, the vasa defe- rentia in the male, and the fallopian' tubes in the female. In the female the vagina and uterus are both developed by extension and 153 division of this canal, — the vagina having in front of it the urethra ; and as development advances, the last portion of the sinus uro-geni- talis is represented by the vestibulum, and is common to the urethra and the vagina. Ac- cording to Valentin, in the male the vasa defe- rentia at first open together in the mesial por- tion of the uro-genital canal ; in the female the same is observed in respect to the fallopian tubes. Rathke states that at a later period a small conical crimpling of the uro-genital sinus occurs near the openings of the vasa deferentia, and that from this the vesiculte seminales are developed, which communicate with the vasa deferentia, and, indirectly, with the sinus, or with the urethra itself. A se- paration takes place between the two vasa deferentia, when each vas deferens, uniting with a corresponding vesicule, opens sepa- rately into the urethra. In the interval be- tween the terminations of the vasa deferentia we find the remains of the uro-genital sinus, which eventually becomes the utriculus, or ve- sicula prostatica, or sinus pocularis. Bischoff thinks that the prostate gland com- mences by a simple thickening of the vasa deferentia near their termination. It is most probably further developed in the same man- ner as the glandular system generally. He agrees with Rathke in the opinion that there exists a septum between the two sides at this portion of the urethra, the vestiges of which are represented by the veru montanum. To complete the analogy between the utri- culus and the female uterus, the vasa ejacu- latoria ought to terminate beneath, or rather within the utriculus, as the fallopian tubes do in the uterus ; and this is said really to hap- pen occasionally. Morgagni mentions two instances of this. I have found it myself, but, it is rare ; yet the fact of even its occurrence now and then adds all we require to complete the evidence in favour of the analogy between these two apparently dissimilar structures. Presuming all that has been stated to be true, we need not tax our ingenuity further, in en- deavouring to assign a use to this heretofore obscure structure the sinus pocularis. The prostate, up to the period of the full development of the organs of generation, is of small size. In the early periods of foetal existence it is composed of two lateral lobes, which coalescing at the fourth or fifth month, give rise to the isthmus and third lobe.* It is rounder in the child, is situated vertically, and is said to be occasionally just reached by the peritonaeum. As we advance in life it becomes firmer in texture and yel- lowish in colour. Mercier says that in the child the anterior part of the gland exceeds the posterior in thickness ; in other words, that the prostatic ring encircling the urethra is thicker above than below. Function of the prostrate gland. — It is the office of the prostate to secrete a bland and * I do not consider tlie isthmus and third lobe as synonymous expressions, and would limit, the former term to that portion of the gland which connects the lateral lobes beneath the urethra. PROSTATE GLAND. 154 somewhat viscid fluid, which is poured into the urethra at the commencement of its course, at that point where the secretion of the testes and vesiculse seminales are re- ceived into the canal. It is well known that the secretion of the prostate is in- creased in quantity under states of venereal excitement; I have, however, some doubts as to whether the secretion effused under such circumstances is wholly prostatic : I cannot help thinking that some of it at least is due to the glands of Cowper and the follicles of the urethra generally ; but, be this as it may, there can be no doubt that the largest quantity of the prostatic fluid is poured into the urethra at the moment of, or prior to, the venereal orgasm ; at least we are justified in drawing this inference from observations made on these parts in animals killed during, or immediately after, the completion of the act of copulation. That the prostatic fluid is subservient to the generative function, may be deduced from these circumstances ; and this is further esta- blished by the fact mentioned by Hunter, that the gland is liable to changes at certain sea- sons, and that in the mole, in winter, the prostate is scarcely discernible, whilst in the spring it becomes of large size, and filled with fluid. We are not aware whether this is the case universally in the animal kingdom. How does the prostatic fluid aid the function of generation ? An old opinion assigns to these accessory glands the office of perfecting and increasing the bulk of the seminal secretion, so that the urethra may be more fully distended by it, and its muscles may be enabled to act more com- pletely in forcibly injecting its contents into the vagina. This idea is, in my mind, rather too mechanical, although it may be advanced in its favour, that these accessory glands are found in all animals, where they exist, to empty themselves into those dilated portions of the urethra, in which the seminal secretion is supposed to accumulate prior to its expulsion. It has been thought by some that the pros- tatic secretion is useful in diluting the semen, so as to increase its bulk, not merely for the more perfect distension of the urethra, but that it may ensure the more easy transmission of this secretion into the female vagina, and thus favour its contact with, and impregnation of, the ovum. As to its defending the orifices of the ejaculatory ducts from the presumed acrimony of the urine, I cannot attach any importance whatever to this notion ; the gland is essentially a sexual organ, and its use must, in some manner or another, be con- nected with the excretion of the seminal fluid, either in the manner just mentioned, or in lu- bricating the surface of the urethra, so as to facilitate the onward passage of this fluid. The very structure of the prostate, which is of the simple follicular character, favours the latter notion. Its position at the commence- ment of the urethra leads to the same conclu- sion. It is probable that its secretion is poured into the urethra prior to the escape of the seminal fluid into the canal ; and it is quite evident that no large glandular masses could have been conveniently placed along the urethra in any other situation ; for however much they vary in number and size, in the various orders of animals, their position near the beginning of the urethra is constant. The prostate gland, with Cowper’s glands and the vesiculac seminales, must be regarded as accessory rather than as organs essential to the generative function. That it is not essential in man, is rendered probable by the persistence of the procreative faculty in many cases of extensive disease of this organ. In connection with this obscure and diffi- cult subject, I think the fact of the prostatic secretion being naturally, as I believe, acid, is a circumstance of some interest. The secre- tion of the testes is well known to be alkaline, and has a strong tendency to coagulate or become inspissated. Is it not probable that the reaction of the prostatic on the seminal fluid may be of use in the maintenance of the fluidity of the latter ? The idea is somewhat confirmed by the fact, that in women the acid secretion of the vagina prevents the coagu- lation of the menstrual blood, and thus favours its discharge. This has been proved by Mr. Whitehead, who found that, if the menstrual fluid was received directly from the os uteri into a speculum, it coagulated like ordinary blood.* Morbid Anatomy. — Hypertrophy. — In ad- vancing years, when all other structures in the body begin to show evidence of a fail- ing nutrition, and are atrophied or wasted by interstitial absorption, the prostate gland, on the contrary, very frequently becomes the subject of a remarkable increase in size. This is so common after the age of fifty, that an enlarged prostate may be almost regarded as one of the necessary contin- gencies of advanced age. It is not, how- ever, exclusively in the old person that this takes place ; it sometimes happens at a much earlier period of life ; nay, a case is men- tioned by Sir Astley Cooper of a boy whose prostate was found, on dissection, of very large size ; but it is not improbable that this remarkable enlargement depended on stru- mous deposit in the gland. In considering this subject, it is important to distinguish between this affection of the prostate and the simple engorgement consequent on acute or chronic inflammation ; these latter conditions occur more frequently between twenty and forty years of age, and depend on stricture of the urethra, or the mal-treatment of severe gonorrhoea. Hypertrophy of the prostate is so insidious in its mode of invasion, thattheonlyindications of its occurrence are evinced by the mechani- cal impediment to the free discharge of the urine, in consequence of the increased size of the gland. No pain, no uneasiness is felt be- fore the prostate has obtained a considerable volume, after which, symptoms of a most dis- tressing character set in, and continue, with more or less severity, to the termination of * On the Causes of Abortion and Sterility, &c., by James AYhitehead, 1847. t PROSTATE GLAND. 155 the patient’s existence. It would be out of place here to enter into the signs which cha- racterise the progress of this disease. I must confine my observations to the state of the gland itself, to the effect produced upon the adjacent structures by its enlargement, and to its cause. In senile hypertrophy, the gland becomes enlarged in all its dimensions ; it expands laterally, extends downwards towards the rec- tum, so as to be readily felt, forming a consi- derable tumour in this situation, and upwards behind the symphysis pubis, so that in a thin person, with the hand firmly pressed upon the hypogastric region, the surgeon can, in some cases, feel it distinctly. Its outer sur- face is smooth and round, or occasionally irregular and nodulated : the two lateral lobes expanding universally, are pressed together, so as to become flattened at their opposed surfaces ; if one increases particularly at one part, as is often the case, there is a corre- sponding indentation in the other, and thus the direct course of the urethra is altered, and the canal is twisted in various directions. The disease is not usually confined to its lateral lobes ; for the third lobe frequently participates in the enlargement. This may happen to a great extent, in some measure, independently of the increase in size of the lateral lobes ; but usually, where the middle lobe is affected, the lateral lobes are enlarged, although the converse of this condition is not so invariable. The middle lobe sometimes forms a simple pyramidal elevation at the urethral orifice ; sometimes a large pendulous or valvular tumour, occasionally rising up- wards from the posterior part of the prostate in the mesial line direct, frequently inclining to one side. It has been known to attain the size of a small orange ; and where it has in- creased to such an extent, it must of neces- sity happen that the base of the tumour is the smallest part of it. Whatever form of en- largement the middle lobe assumes, the tumour always projects towards the bladder : it is frequently knotty or lobulated on the surface. In its increase, the third lobe draws up the prostatic portion of the urethra, and elongates the veru montanum. Very great interest has attached to this condition of the middle lobe, in a surgical point of view, since Sir Everard Home particularly directed the attention of surgeons to Mr. Hunter’s observations upon it, who states “that it sometimes increases so much, as to form a tumour projecting into the cavity of the bladder some inches.” The disease of this part of the gland had not escaped the observation of Morgagni, although he did not attach much importance to it : it was also known to Valsalva. Hypertrophy of the prostate is frequently attended with general induration, so that when cut into, it almost resembles cartilage. This has obviously given rise to the term scirrhous prostate, as applied by the older surgeons to the disease in question. In other instances, it feels softer than natural. The capsule be- comes gradually attenuated by distension, and the direction of the tumour is always towards the part where there is least resistance. It has been very commonly asserted that the left lobe is more frequently hypertrophied than the right. The observation originated with Sir Everard Home. I cannot deny the truth of the assertion; but it is divested of any practical importance, as it is well known that the right lobe is in very many cases the larger of the two. However, the fact that the two are very frequently unequally enlarged, ought to be impressed upon the mind of the surgeon, as he may expect that the course of the urethra will deviate to either side, and (in the introduction of the catheter) in eases of re- tention, from enlarged prostate, he must direct his instrument accordingly. The enormous increase of size which the prostate attains, produces serious incon- venience to the parts adjacent. Thus, inde- pendent of the effect on the nerves of the pel- vis, as indicated by pains in the loins, sacrum, groins, and down the thighs, its influence is most sensibly perceived in the altered state of the urethra, in the bladder, and the rectum. By the enlargement of the prostate, the urethra is increased in length — a fact well knowm to practical surgeons. This actual elongation takes place only in the prostatic portion of the canal ; the diameter of the urethra, so far from being diminished, is really increased ; but the part surrounded by the gland is al- tered in shape ; for, whereas in the natural state the prostatic sinus is longer in a trans- verse than in a vertical direction, it is now quite the reverse : its sides are also approxi- mated by the coaptation of the lateral lobes ; and if any unequal projection of either lobe exists, it takes a tortuous course to reach the bladder, or reaches it by two channels, one on each side of the middle lobe ; besides which, the urethral orifice into the bladder is more or less blocked up by the projection of the middle lobe, or is raised higher than na- tural, the prostatic part of the canal forming a sickle-like curve, the convexity of which is downwards. The prostatic sinus is occa- sionally dilated to such an extent, as to be capable of holding two ounces or more of urine. The veru montanum is placed at a greater distance than natural from the bladder. The bladder becomes either preternaturally dilated, or contracted to a very small size ; these two opposite conditions probably de- pending on the greater or less irritability of the viscus ; sometimes it is sacculated ; its muscular coat is thickened, and its mucous lining becomes the seat of acute or chronic inflammation, with all its accompanying pa- thological changes. So also the ureter and even the kidneys themselves are frequently diseased in the advanced stages of this affection. When the third lobe is much enlarged, it throws the neck of the bladder forwards, and increases the depth of the inferior fundus to such a degree, as to cause the lodgment of calculi in its cavity. In one respect, this circumstance is attended with some advantage, inasmuch as it lulls the symptoms of stone, by preventing PROSTATE GLAND. 1 56 the calculus from coming in contact with the sensitive neck of the bladder. But an obvious inconvenience arises in other cases from the difficulty of seizing calculi under such cir- cumstances, in the operation of lithotrity ; and after a calculus is broken up, it prevents the escape of the fragments, and thus favours the recurrence of the disease. Its influence on the rectum is felt in the flattening of its cavity from before backwards, and by its projection it causes the rectum to rise up on either side of it. Haemorrhoids and prolapsus ani are by no means unfrequent attendants on enlargement of the prostate. On examining with the microscope sections of an hypertrophied prostate with Mr. Quekett, I found numerous crystals in its ducts, which disappeared on adding dilute muriatic acid. Atrophy. — The prostate is liable to atro- phv, but the disease is rare. I have met with it myself occasionally in very old persons. When the gland is altogether diminished in size it is usually more consolidated in its tex- ture. It is, however, liable to another form of atrophy (eccentric atrophy), by which I mean a thinning of its tissue generally, and its conversion into one or more cysts, in conse- quence of continued pressure exerted by the increase in size of calculous concretions in its follicles. “ Cases sometimes occur, in which the whole of one lobe, or even the entire organ, is converted into a thin fibrous capsule, the proper substance of the gland being almost wasted.” — (Crosse’s Pathology.) In those cases the ducts of the prostate are usually increased in size, so as to arrest the progress of the catheter. It generally occurs in connection with urinary calculi, or long-standing stricture. Dr.Baillie met with one instance of atrophied prostate ; it occurred in a case of ectropium of the urinary bladder, and malformation of the organs of generation ; the utriculus pros- taticus was larger than natural. Inflammation. — Inflammation, acute or chronic, not unfrequently attacks the prostate, leading to increase of size, and suppuration of the gland. It is very commonly the result of suppressed gonorrhoeal discharge, and follows the employment of copaiba, cubebs, and power- fully stimulating injections. The signs of this condition are easily understood. With care- ful and somewhat active treatment by leeches, cupping in the perinseum, warm fomentations, &c., the disease terminates in resolution ; but permanent enlargement or suppuration are the too frequent consequences of inflamed pros- tate. An irritable state, characterised by an uneasy sensation referred usually to the end of the penis, and attended by an increase in the secretion of the gland, which can be drawn out in threads, with a frequent desire ofmaking water, indicates an inflamed condition of the prostatic ducts. The discharge is occasionally puriform in appearance. Abscess. — If the inflammation be unsub- dued, suppuration often occurs. The whole tissue of the gland is, in some instances, in- filtrated with pus ; in others a single abscess, of large size, or numerous small abscesses occupy one or both lobes of the prostate. Sir Benjamin Brodie relates an instance of an old man, the subject of abscess of the prostate, containing at least half a pint of pus, which escaped through the catheter, after the urine had been drawn off. Many similar instances are recorded. These large collections are generally the result of an attack of acute in- flammation on an already enlarged prostate. Smaller purulent deposits are met with in various parts of the gland ; so that when after death the pus is washed away, the prostate is found riddled with holes. Such deposits are not uncommonly associated with suppuration of the vesiculae and the adjacent structures ; and are frequently consequent on intense sexual ex- citement and onanism. Lallemand gives many instances of this, and relates one in particular, where the urethral membrane was perforated by numerous apertures, through which the pus escaped, so as to present a sieve-like appear- ance, which he compares to the cribriform lamella of the ethmoid bone. Mr. Curling* mentions a similar case of a young man ex- cessively addicted to onanism, and who died with symptoms of cerebral congestion. The prostate was converted into a multilocular cavity, and the urethra was perforated by numerous large apertures. These openings are the orifices of the prostatic ducts preter- naturally eidarged, suppuration most probably commencing in the minute follicles of the gland. A secretion of a puriform fluid often takes place from the prostatic ducts in cases of severe attacks of gonorrhoea, and small ab- scesses give way one by one. Abscesses of the prostate open in various directions. Not unfrequently they burst into the bladder on the introduction of the ca- theter. Sometimes they open into the urethra on the side of the veru montanum ; or they make their way forward to the perinaeum, and opening externally terminate in the formation of peri nasal fistulas. Occasionally they open at once into the rectum ; or they may burst into the adjacent cellular membrane, and even extend to the penis and scrotum. Ulceration. — This mode of termination of an inflamed prostate is rare. It is one of the most distressing consequences of inflammation, and is only found in cases of hypertrophy of the prostate in old age. It may arise spon- taneously, or it may be the consequence of the rude introduction of the catheter. It is invariably attended with most severe symp- toms, and is generally indicated during life by the mixture of blood with the urine. The mucous membrane of the bladder adjacent is in a state of high inflammation. Ulceration may exist in various degrees, from simple erosion, as after passing a catheter, to a deep ulcer with indurated edges. In one case, re- lated by Sir Benjamin Brodie, the prostate was found ten or twelve times its natural size, making a large circular projection into the bladder, round the internal orifice of the ure- thra. Nearly the whole of this portion was * Curling, on Diseases of the Testicle. PROSTATE GLAND. 157 superficially ulcerated, and in some places the ulcerated surface was incrusted with a thin layer of coagulated lymph. Simple enlargement of the prostate is an- other consequence of common inflammation. It is one of the not unfrequent sequel® of repeated and neglected attacks of gonorrhoea. It is generally accompanied with induration, and is confined to the lateral lobes, rarely im- plicating the middle lobe. This condition is occasionally dependent on the irritation or stricture of the urethra, and subsides on the cure of the latter disease. Tubercles. — The deposit of scrofulous tu- bercles in the prostate is rare. When this happens it is generally found to co-exist with similar deposition in the testicles, vesiculae seminales, and the adjacent lymphatic glands, and is associated with tubercles in the lungs. It occurs occasionally in the form of one large mass, occupying a large portion of the gland, and causing an increase in its size, or many small distinct depositions are found in various situations. Scrofulous tubercles of the pros- tate undergo the same progressive disintegra- tion as in other parts, and terminate in ab- scesses, which take a similar course and direction as common abscesses. I have seen the whole tissue of the gland broken down by the gradual softening of scrofulous tubercles. Mr. Cross, of Cincinnati, met with one in- stance of this disease ; it was in a young man who died in the Cincinnati Hospital of psoas abscess. There were six or eight small masses of a pale yellowish colour, and of a soft curdy consistence, scattered through different parts of the gland, which was considerably reduced in size ; he thinks they are originally formed in the follicles of the gland. Lallemand also mentions a case in which thirty small abscesses, and the same number of crude tubercles were found in the prostate. There were similar deposits in the kidneys. Cancer. — Cancer in any form is extremely rare in the prostate. Carswell regards it as a not uncommon cause of haemorrhage from the urethra, whilst Cruveilhier says that he has never seen an instance of it. — (Walshe on Cancer.) The encephaloid form is that which most commonly attacks this gland ; and, ac- cording to Walshe, in M. Tanchon’s tables, out of 8289 fatal cases of cancer, in five death occurred from the disease in the prostate. Rokitanski regards the affection as very rare, and makes allusion only to the encephaloid variety. When the disease attacks the pros- tate, the gland becomes increased in size. It has been found by Mercier of the size of an ostrich’s egg, “ and was attended with effusion of blood into both lobes, communicating with each other and with the urethra by means of false passages.” In a boy, five years old, Mr. Stafford found the prostate of a globular form, and as bulky as the largest walnut ; the mid- dle lobe was nearly as large as a small hazel nut. — (Walshe.) By the same author, a case is recorded from Langstaff of an encephaloid growth as big as an orange, which sprang principally from the middle lobe. Cancer of the prostate, as it advances, generally makes its way towards the bladder, and thus forms a bleeding mass in the cavity of that viscus, oc- casionally filling it up completely, and giving rise to a distinct hypogastric tumour, whichl have known mistaken for a bladder over-dis- tended with urine, the true nature of which was not suspected until after the introduction of the catheter. The cancerous mass at its base was surrounded with a distinct borderof ulcer- ation, so characteristic of cancerous tumours, when they have made their way into cavities lined with mucous membrane. The secretion of urine is frequently, under this condition, in a great measure suspended. I have known one case where the bladder was tapped above the pubis, under the idea that it was filled with urine ; but little or no urine escaped, and after death the bladder was found filled with a cancerous tumour originating in the prostate ; and no doubt many such in- stances have happened. It is a mistake of no very serious consequence, but might be avoided if a careful examination of symptoms were instituted. If an elastic catheter were gently introduced into the bladder, it would be found to give the impression as if it entered a spongy substance, little urine would escape, and that tinged with blood and mixed with shreds of cerebriform matter : if doubt still existed, a microscopical examination of the substance voided would, I apprehend, set the matter at rest. The introduction of the finger per rectum will assist the diagnosis. True scirrhus of the prostate is extremely rare. Mr. Travers and Sir Benjamin Brodie both allude to supposed cases of this disease, and from the narration there can be little doubt of their genuineness. The former sur- geon examined one case after death, and described the gland as occupied by a tumour, having all the character of scirrhus ; anti the latter mentions an instance “ where the prostate was found much enlarged, and of a stony hardness.” — (Walshe.) Fibrotis tumours, according to Rokitanski, are frequently found in the prostate. They are of a size varying from that of a pea to that of a hazel nut, are round or oval, causing, when seated at the peripheral portion of the gland, knotty protuberances on its surface. They are always attended with distinct hyper- trophy of the gland. This eminent patho- logist attaches great interest to them, on account of their similarity to fibrous tumours of the uterus. They are of very frequent oc- currence ; and in many cases of the enlarged prostate of old men that I have had an op- portunity of examining, I found them readily distinguishable on section. This subject has been alluded to before, in the account of the morbid anatomy of the enlarged prostate. Cystic Prostate. — The prostate, like the kidney, is occasionally the seat of cystic disease. It is characterised by the formation of cysts in various parts of the gland. It is extremely rare. There is an excellent exam- ple of it in the Museum of the College of Surgeons. The gland was hypertrophied, and 158 PROSTATE GLAND. on section was found studded here and there with cysts containing fluid. These are, in all probability, dilated and closed follicles; and in this respect they bear a strong analogy to the cysts of the kidney, which are found to be dilated uriniferous tubes. In the situation of the uvula vesicas, the fold of mucous membrane is occasionally thrown up, so as to form a remarkable pro- jection or bar at the neck of the bladder. Mr. Guthrie especially directed the attention of surgeons to this, but it has been met with often by others, and there is a good repre- sentation of it in Baillie’s Morbid Anatomy. No doubt it has often been confounded with supposed enlargement of the middle lobe of the prostate, with which it is often combined, but of which, in many cases, it is wholly in- dependent. In a surgical point of view it is of very great interest. The bar in question, in its most simple form, consists simply of a double fold of mucous membrane, raised at right angles from the bladder ; in other cases, there is found between the layers of mucous membrane a quantity of a substance of an in- termixture of elastic and organic muscular tissue, similar to what is found in the neck of the bladder in the normal condition ; whilst in other instances, apparently in the more ad- vanced stages of the disease, the middle lobe of the prostate, considerably hypertrophied, is found as if it had forced its way between the mucous layers, and thus carried the fold with it ; in the latter condition, it will be found in the form of two wing-like processes, one on either side, connecting the middle lobe to the side of the bladder. The disease is necessarily attended with difficult micturition, and leads to retention of urine. The diagnosis between retention from this cause and from enlarged third lobe is difficult, but practically it is not unimportant, as Mr. Guthrie thinks it may be cured. In the rough introduction of the catheter or bougie, the bar is sometimes perforated. This sur- geon found in one case as many as fifty cal- culi behind this projection. It leads, if neg- lected, to similar changes in the bladder, as are found in cases of enlarged prostate. Prostatic Concretions. — The formation of calculous concretions in the minute follicles of the gland are not by any means of unfre- quent occurrence. They are not to be con- founded with calculi of larger size, which have been long recognised by pathologists, and have been especially alluded to and described by Baillie, Woollaston, Cruveilhier, and Prout. They have very recently been examined by Mr. John Quekett and Dr. C. H. Jones, the latter of whom has published a paper on the subject in the first number of the Transac- tions of the Pathological Society, and in the Medical Gazette of August 20th, 1847. The following is the result of the microscopical observations on this subject : — The calculi are found in great numbers in the follicles of the gland, presenting sometimes a deep yellow or red colour ; occasionally they are pale and colourless, remarkably small, and scarcely to be distinguished from the tissue in which they are imbedded. Dr. Jones describes their mode of formation thus ; “ They arise in a large oval vesicle, of a single wall of homo- geneous membrane. This is occupied by a colourless finely-mottled substance, in the centre of which a nuclear corpuscle some- times occurs. Their mean diameter is about ■iu10uth of an inch. In those of larger size, the envelope is still seen, but the contained amorphous matter is beginning to be arranged in layers concentric to the envelope. In the further stage, the vesicles measure -p-J^-th of an inch or more, showing concentric layers, which are more developed on one side than on an- other, like so many repetitions of the original envelope, the intervals between the layers being occupied by a finely-mottled deep-yellow or red substance. There is a central cavity corresponding with the external contour in its form, which is triangular, with rounded angles or quadrilateral. From this normal appear- ance, these bodies present numerous variations in form and internal arrangement, and appear to occupy an intermediate position between organic growths and inorganic concretions : to the former, by their vesicular origin and by their growth, which chiefly appears to take place by the dilatation of the vesicle and suc- cessive depositions in its interior ; to the latter, by their shape, their tendency to become infiltrated with earthy matter, and to pass into the condition of a dead amorphous mass of a deep yellow red, even almost black. The chemical composition varies probably with their different stages of development, at first consisting of little else but animal matter, then acquiring, especially when in a state of de- generation, calcareous salts, stated by Dr. Prout to be phosphate, with a little carbonate of lime. The colouring matter is unaffected by ether, liquor potassae, and muriatic acid.” Fig. 107. Prostatic concretions. These minute concretions in the follicles and tubes of the prostate have been investi- PROSTATE GLAND. 159 gated by Mr. Quekett, who, on submitting sec- tions of the gland either in a healthy or dis- eased condition, to microscopical examination, has met with them so frequently, that they would seem to be a part of the natural consti- tuents of the gland or its secretion. He de- scribes them as commencing by a deposit of earthy matter in the secreting cells of the gland ; they increase in size either by aggregation, or by deposition in the form of concentric layers ; in the former case they mould themselves to the follicles, in the latter they present the ap- pearance of an ordinary lithic acid calculus on section. Where many cells were together, the parietes of the cells in contact are de- stroyed ; so that by adding dilute muriatic acid, and thus dissolving the earthy matter, a multilocular cavity remains. In consequence of the manner in which they mould themselves to the follicles, they frequently present an appearance externally like mulberry calculi.* The opinion of Prout that the deposition of earthy salts is the result of a deranged ac- tion in a mucous membrane appears thus fully borne out. In a case which I recently ex- amined with Mr. Quekett the concretions were exceedingly numerous ; and this was especially remarkable in the middle lobe of the prostate. The gland had been removed from a young man who had died of phthisis, and was of the natural size. The middle lobe was much firmer than either lateral lobe They are so- luble in acetic acid by the aid of heat. Prostatic Calculi. — It is most probable that these concretions undergo an early solution ; thus yielding up their granular or amorphous contents to form a part of the secretion of the gland. This is the opinion of Dr. Jones. But if they are not removed in this manner they become the nuclei of prostatic calculi. Prostatic calculi are thus formed in the gland, occasionally in immense numbers ; they are generally rounded in form, and from their pearly semi-transparent appearance, Dr. Wollaston compared them to grains of pearl barley. They become covered with a brownish coating from a deposit from the natural secre- tion of the gland. Continuing to increase in size, they come in contact with one another, and at the points of contact are as it were articulated together. They are smooth upon the surface, and often resemble porcelain from the high polish they obtain. As they increase still further in size they cause absorption of the surrounding glandular substance, and thus convert the gland into a multilocular bag, in which as many as fifty or sixty calculi have been seen. In this condition, if the finger is passed per anum, the prostate gives the feel of a bag of marbles. Sometimes there is only a single large cavity in one lobe filled with a single calculus. The smaller stones often escape into the bladder through the dilated ducts, and are readily extracted by the urethral forceps. When divided they' exhibit a radiated and laminated structure; or they are com- pact. * See Guy on Cause and Treatment of Stricture of the Urethra, and Diseases of the Prostate Gland, 1845. From the analysis which has been made of the prostatic calculi in the College of Surgeons, it appears that the relative proportion of phosphoric acid and lime in all the varieties of these calculi appears to vary considerably, although they may, in all probability, be re- duced to two salts, — the neutral phosphate of lime, or the diphosphate, which exists in those varieties that are partially fusible before the blowpipe, and which generally exhibit a crystalline structure; and the basic phosphate of lime which is completely infusible by the mouth of the blowpipe. In estimating the fusi- bility of these compounds, care must be taken that none of the triple phosphate is present.* When they pass into the bladder, they excite irritation of its mucous surface, and become coated with the triple phosphate; or if a large stone remains in the prostatic portion of the urethra, it may cause a deposit of lithic acid on its surface from the urine which is conti- nually passing over it. A single calculus sometimes extends from the prostate into the membranous part of the urethra, which be- comes much dilated. In these cases the cal- culus has usually an elongated, somewhat conical figure, and consists of two or three separate portions, which are closely adapted to each other, and have polished articulating surfaces at the point of contact. The rounded extremity of one calculus is often received into a corresponding concavity of another. These calculi almost always contain a larger portion of phosphate and carbonate of lime, than those found in any other situation. When the prostate is completely disorganised and converted into a mere cyst, the calculi found in its cavity are of the fusible character, or contain more or less of the triple phosphates. It sometimes happens that the phosphates are secreted by the prostate in immense quan- tities, and are excreted with the urine, giving it a milky aspect. This may be confounded with a similar deposit from the urine itself, but it is generally accompanied by symptoms of irritation of the prostate gland and neck of the bladder — as discharge from the urethra ; hence the diagnosis is not difficult. “ Vogel, in his pathological anatomy of the human body, has given an account of these prostatic calculi : he described them of small size, not larger than a pin’s head, and usually of a brownish, reddish-brown, or yellowish-brown colour, presenting a crystalline or laminated arrangement, with a polyhedric or facetted surface. He says that they are formed by a precipitate of phosphate of lime. “ Lassaigne has given an analysis of the quantitative composition of these concretions. Thus in 100 parts there are contained Basic phosphate of lime . . 84'5 Carbonate of lime . . . 0‘5 Animal matter (mucus, &c.) . I5'0 It is presumed that they are formed by a de- position of these salts when existing in excess in the prostatic secretion. Similar concre- * Catalogue of Calculi contained in the Museum of the Royal College of Surgeons in London, 1842. 160 PROSTATE GLAND. tions are occasionally met with in the vesiculae seminales and vasa deferentia; but, according to Peschier, their analysis differs slightly from prostatic concretions. Thus he found in 100 parts Phosphate of lime . . . 90'0 Carbonate of lime . . . 2'0 Animal matter . . . . 1'0”# Comparative Anatomy. — Assuming the prostate to be represented by a glandular structure placed at or near the termination of the vas deferens, it is found in many of the invertebrate animals. As a general rule, it is only discovered in those pos- sessed of an intromittent organ ; this, how- ever is not invariable. In the medicinal leech, among the annellata, according to Owen and Brandt, the two vasa deferentia and the two sacculated vesiculae seminales send their ducts to a common prostatic body, from which the penis is continued. “ In the centipede, among myriapoda, a minute efferent tube is continued from both ends of each testis, which tubes unite with those of the adjoining organ, and ultimately form a single vas deferens, which, having received the ducts of three pairs of small prostatic glands, terminate in the cloaca. In the male aphis there is a long pyri- form vesicular gland attached to each lateral vas deferens, and in many insects representa- tives of prostatic glands communicate with the ductus ejaculatorius.” f In the slug, among gasteropoda, the vas deferens is joined by the short and simple duct of a small pros- tatic sac ; and this is the case in the common snail, in whom the duct is, however, longer. In the cephalopoda, as in the octopus, “ the anterior extremity of the contractile vesicula, into which the efferent duct opens, communi- cates with a wide, bent, coecal tube (prostate), with thick glandular parietes, and having the form of a simple pouch in the sepia. The prostate in the sepio/a communicates by a long and slender duct with the vesiculas semi- nales.” t In mammalia, two varieties of prostate are found, distinguishable as to structure from each other : one, the cellular, in which small cells open into a central cavity, from which a large duct arises ; and the other, the follicular, composed, as Muller says, “ of large intesti- nules, or larger ramose follicles.” In the ape tribe, the form of the prostate is larger from above downwards than from before backwards, and surrounds the urethra in the form of a crescent. In position, size, and structure, it resembles that of man. In the mandril some accessory lobes are found. The prostate of the maids sends off two pro- longations, which surround the excretory ducts of the vesiculae seminales. In the tarsier, there are two distinct glands, placed in front of the vesiculae seminales, on the side of the urethra. The galeopitheci have a single prostate * Vogel’s Pathological Anatomy of the Human Body, translated by Dr. G. E. Day. f Owen's Lectures on the Invertebrate Animals. of large size, surrounding the base of the vesiculae. In the roussette, the prostate is simple, and surrounds a large portion of the circum- ference of the urethra. In the dormouse, it surrounds the whole circumference of the urethra, and is composed of a number of lobules. In the hedgehog, the prostates are four in number, and they belong to the tubular class. The superior prostates are the larger, and are composed of long flexuous tubes, united into lobules, which form lobes, whose tubes re- unite to form a single excretory duct, which pierces the superior surface of the urethra. They are attached by processes of the perito- naeum to the abdominal muscles. — (Hunter.) Two other bundles of smaller size, and of a rounded form, represent the inferior prostates. They are composed of smaller tubes, which separating in the form of a fan, pass towards the circumference of the gland, and terminate in coecal ends. The excretory ducts open one on either side of the veru montanum. The tubes are composed of membranes of extreme delicacy. In the mole, the prostate is single, and is formed of membranous tubes folded upon themselves. At the period of heat, it in- creases so enormously as to exceed the urinary bladder in size ; it is placed around the urethra in front of the bladder. The prostate of the bear is confounded with the dilatation of the united vasa deferentia. It surrounds the beginning of the urethra, and forms a bed for the canal of variable thickness, according to the species. In the otter, weasel, and marten, it consists of a thin layer, without any enlargement. In the ichneumon, there is a gland of consider- able size, composed of distinct lobes, situated on the rectal aspect of the urethra ; each lobe has a distinct duct. In the dog and cat, it forms a large promi- nent collar around the urethra; it resembles the human prostate in structure, and mode of termination of its ducts. In the hyena, it is of large size ; and in the civet it forms two tubercles in front of the in- sertion of the vasa deferentia. In the marmott, among the rodentia, it is divided into two lobes, and forms a consider- able swelling around the commencement of the urethra. The glandular covering of the vesiculae seminales, which extends below the muscular structure of the urethra, represents the pros- tate gland in the rabbit. In the squirrel, it is as long as the muscular portion of the urethra, of large size, ovoid in shape, flattened from above, and is divided into two lobes ; it adheres to the urethra by two points, where its excretory ducts pene- trate the canal. According to Muller, in the rat genus, be- sides three glands of different structure on each side, the urethra is surrounded by a glandular mass, consisting of bunches of vesi- cles, representing the prostate. PROSTATE GLAND. 161 In the agouti, the prostates are composed of a trunk, divided into branches and ramusculi, terminating in vesicular extremities. In the guinea-pig, the situation of the pros- tate is occupied by a number of tubes folded upon themselves, and connected together by loose cellular membrane. The elephant has four prostate glands, two on each side, external to the vesiculae semi- nales, and near their base ; they are of un- equal size, and very small in proportion to the size of the other glands connected with the generative function. They are muscular ex- ternally, and are indistinctly lobulated. They form a good illustration of the cellular type of prostates, each consisting of a principal ca- vity, into which smaller cavities open. The smaller cells represent so many cul-de-sacs of various sizes, communicating with each other and with the principal cavity ; the excretory duct is of large size, and passes by the side of that of the neighbouring gland, to open sepa- rately in the urethra by the side of the veru montanum. In the ivild boar the prostate is divided into lobes, is very compact in its structure, and forms a considerable projection at the begin- ning of the urethra. There is also found in this animal a glandular mass, analogous to the prostate, surrounding the muscular portion of the urethra, thickest at the commencement of this canal, and surrounded by muscular fibres coming from the neck of the bladder. In solipedes there are two prostates, situ- ated by the side of the vesiculae ; the cavities of these are large, and the parenchyma small in quantity ; they are covered by' muscular fibres coming from the vesiculae and neck of the bladder ; their excretory ducts terminate by many orifices on either side of the ducts of the vesiculae. The ruminants have also two prostates, precisely similar to the preceding. They are larger in the ram and bull, and are composed of distinct lobes, each containing small cells, which communicate with a large central ca- vity ; this opens by a duct in a large lacuna of the veru montanum, either internal to or be- hind the vas deferens. In the stag, axis, and buffalo they are smooth, and of a regularly oval shape, and have a central cavity commu- nicating by large openings with smaller cavi- ties ; each has a single duct, which terminates generally behind the corresponding vas de- ferens. The only difference in this class is in regard to size ; for in the chamois each is as large as a pullet’s egg, and contains a propor- tionably large cavity ; so that it has been occasionally mistaken for a reservoir of semi- nal fluid. In the seal, amongst the quadri- rhn.es, it resembles that of the otter. In the cetacea there is a large glandular mass, covering a large portion of the first part of the urethra, especially at the upper part, covered bv a strong muscle. When a section is made, it is found to consist of large cells ; its ducts open separately by numerous orifices on the urethra. VOL. IV. In the marsupial sub-class, as in the kanga- roo, the prostate is found surrounding the com- mencement of the urethra, of large size, and conical in shape, with base behind, apex in front ; it is surrounded by a strong musculo- membranous capsule. It exceeds in diameter the contracted bladder, and is made up of tubes ramifying perpendicularly to the urethra, ■which subdividing terminate in minute coeca upon the surface of the gland. It presents a similar arrangement in the opossum ; whilst in the wombat its existence is doubtful. Carus has described in birds a dilatation of the vas deferens, a rudimentary vesicula semi- nalis, and a small gland like a prostate near the termination of the vas deferens. This is not admitted by Owen. In the ornithorynchus paradoxus we find two round glandular bodies representing Cowper’s glands, but which may be fairly regarded as a rudimentary prostate. Amongst amphibious reptiles, glands ana- logous to the prostate, or Cowper’s glands, are found. In the salamander they are com- posed of two lobes ; one placed horizontally, and the other vertically ; the former, in the common salamander is heart-shaped, with the point behind ; and in its centre a fissure is seen. The vertical lobe is raised obliquely towards the dorsal aspect, so that an interval is left between them for the passage of the kidneys ; a muscle separates the two. In the black salamander, each gland is com- posed of two lobes. In the Tritons the part of the prostate which corresponds with the inferior lobe is still more complicated; it forms the wall of the vestibulum in the shape of a cup. Besides this, there are two pelvic pros- tates corresponding to the vertical lobe of the vestibular prostate of the salamander ; they occupy the dorsal aspect of the vestibule and the pelvis, and each is subdivided into two lobes. Their excretory ducts open in the mesian line of the furthest point of the vesti- bule. The Tritons have a third prostate occu- pying a large portion of the abdominal muscles under the peritonaeum. In structure they re- semble those of the hedgehog. — (Cuvier.) Bibliography. — Natural Structure. — See anatomical works in general. Muller, De penitiori Glandularum Structura, 1880. Physiology. — Por the opinions of the ancients on this subject see Haller's Elementa Physiologiae, vol. 7., and the opinions of modem physiologists are set forth in the works of physiology generally. Cow- per, Glandularum quarundam nuper detectarum, 1702. Comparative Anatomy. — See vol. 8. of Cuvier’s Leyons d’Anatomie Comparee. Lectures on Compa- rative Anatomy, by Dr. Grant, in the Lancet, and Lectures on Comparative Anatomy by Rymer Jones. See also various articles by Professor Owen on Com- parative Anatomy in this Cyclopaedia. Owen’s Lectures on the Comparative Anatomy of the Invertcbrata, 1843. Wagner’s Elements of the Com- parative Anatomy of the Vertebrate Animals, trans- lated by Tulk, 1845. Development. — Ackerman , Infantis Androgyni Historica, Jena, 1805. Meckel, Abhandlungen aus der menschl. und vergl. Anatomie, 1806. Tiede- man, Der Kopflosen Missgeburten, 1819. Muller, Bildungeschichte der Genitalien, 1830, and Archiv, M 1G2 PROTEIN. 1847. Rathhe, Abhandl. nnd Beitrage, 1830. Valentin, Entwickelungsgeschichte, Berlin, 1835. Baer, Entwickelungsgeschichte, 1837. Coste, Em- bryogenie compare'e, 1837. Bischoff, Entwicke- lungsgeschichte der Silugethiere und des Menschen, 1842. Weber, ZusUtze zur Lehi'e vom Baue der Geschlechtsorgane, Leipsig, 1846. Morbid Anatomy. — Bonctus, Sepulchretum,1700. Morgagni's Do Sedibus et Causis Morhorum, 1760. Hunter on the Venereal Disease, 1788, 2d edition. Baillie’s Morbid Anatomy, 1793. Home, Practical Treatise on the Diseases of the Prostate Gland, 1811. Wilson on the Diseases of the Urinary Organs, 1821. Howship on Diseases affecting Urinary Organs, 1823. LaUcmand, Observations surles Maladiesdes Organes Genito-Urinaires, 1825-27. Amussat, Le9ons sur les Retentions d’Urine Caustics, & c. See., 1832. Guthrie on the Anatomy and Diseases of the Neck of the Bladder and Prostate Gland, 1834. Merrier. Re- cherches sur les Maladies de la Prostate des Vieillards, 1836. Carswell’s Pathological Anatomy, 1833-38. Crosse’s Pathological Anatomy, vol. ii., Boston, 1839. Coulson, Diseases of the Bladder and Prostate Gland, 1840. Civiale, Maladies des Organes Genito-Uri- naires, 1841. Sir Benjamin Brodie on the Diseases of the Urinary Organs, 3d ed. 1842. Rohitanski, Handbuch der Patholog. Anatomie, 1844. Guy on Diseases of the Prostate Gland, 1845. Engel, Entwurf einer Pathologisch Anatomischen Propa- deutik. 1845. Walshe on Cancer. Concretions and Calculi. — Marcet, An Essay on the Chemical History and Medical Treatment of Calculous Disorders, 2d edition, 1819. Prout, An Enquiry into the Nature and Treatment of Diabetes, Calculus, and other Affections of the Urinary Organs. Cuveilhier’s Pathological Ana- tomy, 1828. Sir Astley Cooper's Lectures, by Tyrrell, 1824-7. Crosse on the Nature and Treat- ment and Extraction of the Urinary Calculus, 1835. Catalogue of Calculi of Royal College of Surgeons, 1842. Dr. C. II. Jones on Calculous Concretions of the Prostate ; see Medical Gazette for Aug. 20. 1847. Vogel’s Pathological Anatomy, translated by Dr. G. E. Day, 1847. Dupuytren sur les Calculs de la Pros- tate, dans Bull, de la Gal. de Med., tom. vii. p. 135. ( John Adams.) PROTEIN, (from TTpurebu, I am first,) is the name given by its discoverer, Mulder, to a chemical substance of the highest interest and importance ; since it appears to form the basis of by far the greater portion of the bodies of all animals. When pure fibrin , of which animal flesh or muscle chiefly consists, is analysed, it is found to be composed of C40 H31 N5 012 and a small quantity of sulphur and phosphorus. Albumen, whether obtained from the serum of the blood, white of egg, or any of the albumi- nous tissues of the body, is found also to con- sist of C4Q II31 N5 d12 and a little sulphur and phosphorus. Casein, too, or the curd of milk, yields on analysis C40 H31 Ns 012 and a little sulphur, differing from the others in not containing any phosphorus. Hence it appears that fibrin, albumen, and casein, are, chemically speaking, almost identically the same ; and that if we were enabled to separate from each the minute portion of sulphur and phos- phorus, we should obtain a compound in every case the same. Such a substance is protein ; so called from its being the initial letter, as it were, of all this class of organic principles. I shall first describe it as obtained artifi- cial!}', together with the changes produced upon it by reagents, and afterwards speak of its more common natural modifications, which play so important a part in building up the fabric of organic beings. Protein is most readily obtained from the white of egg, which, as is well known, consists of a solution of nearly pure albumen, contained in a delicate network of cellular membrane. This substance should be well beaten up, in order to break the minute cells in which the albumen is lodged, mixed with about an equal bulk of water, anil filtered through a linen cloth to separate the cellular matter, which is insoluble in water ; or it may be allowed to stand until this has subsided to the bottom of the vessel, when the clear liquid may be poured off, or removed by means of a syphon. The solution should then be evaporated to dryness on a water bath, the residue pounded in a mortar, and washed successively with alcohol, ether, and dilute hydrochloric acid, by which means it is purified from extractive matters, fat, phosphate of lime, and the other salts with which it is associated. The pure albumen thus obtained is digested for several hours in a dilute solution of caustic potash, at a temperature of from 120° to 130° ; it readily dissolves in the alkaline solution, and the sulphur and phos- phorus are gradually separated, forming sul- phuret of potassium, and phosphate of potash. Acetic acid is now added in very slight excess, when the protein separates in the form of a white flocculent precipitate, which, when washed with water until all soluble matter is removed, and dried at 212°, is pure protein. In order to asertain, however, whether the whole of the sulphur is removed, a small quan- tity should be dissolved in potash, and some of the solution boiled in two test tubes, to one of which a drop of solution of acetate of lead is added. They will both become rather brown, owing to the decomposition of the protein; but if any sulphur is present, the portion to which the lead had been added will become, after boiling for a few minutes, much darker in colour than the other, owing to the formation of sulphuret of lead. Protein, when dry, is a hard, semitransparent brownish yellow substance, having a good deal the appearance of amber. It is without taste or smell, and when exposed to damp air rapidly absorbs moisture, which may be expelled by heating it to about 220°. When further heated it melts, and almost immediately afterwards begins to decompose, leaving a residue of char- coal, which, if ignited for some little time in the air, burns completely away, leaving scarcely a trace of incombustible ash. Protein is in- soluble in water, alcohol, and ether ; it appears to combine with most of the mineral acids, forming compounds which may be considered neutral, some of which are soluble in water, though insoluble in an excess of the acid. Tribasic phosphoric, and acetic acids, how- ever, do not reprecipitate it when added in excess. It combines also with the alkalies, giving rise to soluble compounds, from which the protein may be again separated by the ad- dition of an acid. It may be thrown down in an PROTEIN. nsolrible form from any of its acid solutions by the ferrocyanide and ferridcyanide of potas- sium, which are among the most delicate tests for it ; also, by absolute alcohol, tannin, many of the metallic salts, and by carefully neutral- izing with an alkali. Tritoxide of protein. — Though protein may be said to be absolutely insoluble in water, it may by prolonged ebullition with ac- cess of air be rendered completely soluble. This is owing to the formation of a soluble oxide of protein, represented by the formula C40 H31 N5 Oj5 + HO, containing three additional equivalents of oxygen, and which Mulder has called tritoxide of protein. This interesting compound may be more easily prepared from the chlorite of protein (which I shall presently describe) by the addition of ammonia; the muriate of ammonia which is formed at the same time being afterwards separated by washing with alcohol. Tritoxide of protein has, when dry, very much the same appearance as protein ; it is readily soluble in water, nearly insoluble in alcohol, and completely so in ether. It dis- solves in sulphuric and hydrochloric acids and the alkalies, but is precipitated from its solution in water by dilute sulphuric acid, tannin, and several metallic salts, forming compounds with their oxides, having for the most part the formula (C4e Hai N5 01S + MO) + (C40 H31 N5 01S + HO). With nitric acid it behaves like protein, becoming yellow, and forming xanthoproteic acid. Water in which meat has been boiled, as broth, soup, &c., owes its nourishing properties mainly to the tritoxide of protein which is formed during ebullition ; and according to Mulder, both this and the binoxide are formed in meat during the process of roasting. Binoxide of protein. — The other compound of protein and oxygen just alluded to, called by Mulder the binoxide , consists of C40 H31 oI4 or the elements of protein pius two equivalents of oxygen. Both this and the tri- toxide exist ready formed in the* buffy coat of the blood, which, according to Mulder, con- sists chiefly of these two oxides. Binoxide of protein may be obtained by boiling fibrin in water for many hours, when the protein gra- dually combines with at first two, and even- tually three equivalents of oxygen, becoming successively binoxide, and (if the ebullition is continued long enough) tritoxide; the latter dissolves as it is formed, and may be separated from the insoluble binoxide by washing with water. This process is, however, tedious, and it is more readily obtained from hair, in the following manner. The hair should be freed from grease by washing with ether, and dis- solved in rather a dilute solution of caustic potash, with the aid of a gentle heat, not ex- ceeding 120° or 130°. A mixed solution of protein and its binoxide is in this way obtained, from which the protein is first separated by neutralizing the solution with acetic acid, and after filtration the binoxide is precipitated by the further addition of a decided excess of acid. It appears as a yellowish flocculent precipitate, 103 and when washed and dried has a dark resin- like appearance. Bouchardat obtained a substance by digest- ing moist fibrin in water acidified with one or two-thousandth of its weight of hydrochloric acid, in which it gradually dissolved, which he called albuminose ; it has since been prepared and analysed by Mulder, who considers it to be identical with binoxide of protein ; but Liebig, who has recently examined it, says that it cannot be obtained free from sulphur, and consequently that it is not pure binoxide of protein. This oxide is insoluble in water, alcohol, and ether, but dissolves in most of the dilute acids, and in solutions of potash and ammonia; it is precipitated from its acid solu- tions by ferrocyanide and ferridcyanide of po- tassium, and several other metallic salts. Nitric acid decomposes it, forming xanthoproteic acid, but the yellow colour produced by it is less intense than that obtained with protein. These oxides ofprotein possess considerable physiological interest, from the circumstance that they are contained in the blood, in small quantity during health, but much more abun- dantly in some forms of.disease. It is probable that they are formed during every act of respi- ration by the action of the inspired oxygen on the globules or fibrinous matter of the blood ; and Mulder is of opinion that it is through their instrumentality that the atmospheric oxygen is conveyed to the capillaries, there to be employed in effecting the necessary changes in the substance of the body. During fever, when respiration goes on with more than ordinary rapidity, these oxides are formed in much larger quantity; hence the buffy coat of diseased blood, which was formerly considered to be merely fibrin, consists almost entirely of oxidized protein ; and pus, false membranes, and other morbid products contain it in con- siderable quantity. Mulder has recently obtained a third oxide of protein, represented by the formula C40 H31 N5 O20 or protein plus eight equiva- lents of oxygen. As it has not, however, been found to exist naturally in the animal body, it is inferior in point of interest to the other two. Like the tritoxide it is soluble, and is obtained by boiling glutin or yeast for a length of time in water. By the action of chemical reagents on pro- tein a multitude of new compounds are formed, most of which have been only imperfectly examined, and indeed possess but little real interest. I will describe a few of the most important. Protein and chlorine. — When a current of chlorine is passed through a solution of albu- men, or any of the other modifications of pro- tein, a substance is produced, containing C40 H31 N6 015 Cl j, which Mulder considers to be a chlorite ofprotein, (C40 LI31 N6 Ola + Cl 03). It appears to be formed at the ex- pense of three equivalents of water ; three equivalents of hydrochloric acid and one of chlorous acid being simultaneously produced, the latter uniting with the protein. It sepa- rates as a snow-white flaky precipitate, and m 2 PROTEIN. IGA when dried, is hard, semitransparent, and nearly colourless. This substance is sometimes called chloroproteic acid, since it is found to combine without decomposition with several metallic oxides. When treated with ammonia, however, it is decomposed, nitrogen gas is given off, and tritoxide of protein is formed, together with hydrochloric acid, which combines with the excess of ammonia. This is the most conve- nient way of preparing the tritoxide, as it is easily separated from the muriate of ammonia by washing with alcohol, in which it is in- soluble. Protein and nitric acid. — By the action of nitric acid on protein compounds, oxalic acid, ammonia, nitrogen, nitric oxide, together with a new compound called Xanthoproteic acid, are obtained ; which latter, being insoluble, is readily purified by washing with water. Xan- thoproteic acid is of a bright yellow colour, from which circumstance it derives its name : it reddens litmus, is uncrystallizable, tasteless, and, when strongly heated, does not melt, but is decomposed, giving off the smell of burnt feathers. It is soluble in strong acids, and when water is added to the solution, a precipi- tate, containing both the acids in a loose state of combination, is thrown down. It forms with metallic oxides true salts, most of which are of a deep orange-colour, and insoluble in water; the alkaline xanthoproteates, however, are soluble. It is bibasic, and consists of C34 H.,4 N4012 + 2 HO. The troublesome and indelible stain which nitric acid causes when dropped on the skin is owing to the formation of this substance. Protein and sulphuric acid. — When protein is treated with strong sulphuric acid it forms a white insoluble compound, called by Mulder sulphoproteic acid, containing C40, H31, N5, 0,2, + S03. To purify it, it should be washed with cold water as long as the wash- ings give a precipitate with baryta water: when dry, it is hard, tough, semitransparent, and nearly colourless ; it forms with alkalies, so- luble, and with the other oxides, insoluble, sulphoproteates. There is another compound of protein and sulphuric acid, called by Mulder sidphobiprotcic acid, which is formed when dilute sulphuric acid is gradually added to a solution of protein in acetic acid : it appears to consist of two equivalents of protein, two of water, and one of sulphuric acid, and is represented by the formula C80 H62 N10 O a4 + 2 HO + S03. If a protein compound be heated with sul- phuric acid it becomes purple, but the colour disappears on dilution with water. Protein and hydrochloric acid. — Concen- trated hydrochloric acid slowly dissolves pro- tein even at common temperatures, and still more readily when gently warmed : the solu- tion is at first yellowish, but if the air is not excluded, the colour soon changes to a deep blue or purple. The appearance of this blue colour is one of the most striking tests for protein and its modifications, fibrin, albumen, and casein, as it is produced in them all by hydrochloric acid. When allowed to boil, if the acid is strong, a black substance similar to ulmic acid is formed, together with muriate of ammonia. Protein and potash. — The action of potash on protein possesses considerable interest. When treated with a dilute solution of the alkali, in the cold, it readily dissolves, and, ac- cording to Mulder, a little ammonia is always given off, however dilute the alkaline solution may be. When boiled in a strong solution of potash it is completely decomposed ; ammonia, carbonic, and formic acids are formed, together with three new compounds, which have been called leucin, protid, erythroprotid. To obtain these substances in a state of purity, the fol- lowing process may be adopted. The protein compound is boiled with solution of potash as long as any ammonia is given off, and then neutralized with sulphuric acid, which disen- gages the carbonic acid and combines with the excess of potash : the solution is then eva- porated to dryness on a water-bath, by which means the greater part of the formic acid is volatilized. The organic compounds are then separated from the sulphate of potash by re- peated boiling in alcohol, in which they are all more or less soluble. On cooling, the alco- holic solution deposits the erythroprotid, which is of a reddish-brown colour, and nearly in- soluble in cold alcohol. When left for a short time to spontaneous evaporation, the leucin crystallizes out, and the liquid then contains only protid, with a trace of erythroprotid, and a little formiate of potash. Erythroprotid, when pure, is of a fine red colour ; it is soluble in boiling alcohol and in water, and is precipitated from its solutions, of a rose red colour, by many of the metallic salts, as those of silver, mercury, and lead : it is thrown down also by tannic acid. When a current of sulphuretted hydrogen is passed through its aqueous solution, it gradually be- comes colourless ; but if the solution, thus treated, be kept in vacuo a short time, the colour returns. The formula of erythroprotid isC13 He NO,. Protid ( C13 H9 N04) may be separated from the impure alcoholic solution by diluting with water, and precipitating with subacetate of lead, which throws down protid, but not erythroprotid, which latter is also present in small quantity. The precipitate is washed with water, and decomposed by sulphuretted hydrogen ; the solution is filtered and evapo- rated, after which the protid is left in a state of purity. It is of a pale yellow colour, amor- phous, and, when dry, very brittle. It differs from erythroprotid in not being precipitated from its solutions by any of the metallic salts except basic acetate of lead; while erythro- protid is not affected by that reagent : conse- quently if the two exist together in solution, the erythroprotid may be thrown down by the neutral acetate, and the protid by the basic salt. Leucin, which gradually separates when the alcoholic solution is concentrated, is a crystal- line substance closely resembling chloresterine in appearance : it consists of Cl5, II, 2 N04. PROTEIN. 165 It is tolerably soluble in water and alcohol, but quite insoluble in ether ; and when heated to about 340° it sublimes without decomposition. When treated with nitric acid, a crystalline nitroleucic acid is formed, consisting of C12 Hi, N04 + NOs + HO. 2 Eqnivts. Erythroprotid C2 , H n2 o10l 2 „ Protid . . . . C26 H1S n2 o8 2 „ Leucin . . . . C24 H24 n2 Oe 4 „ Ammonia . . H12 n4 2 „ Carbonic acid C2 o4 <■ 1 „ Formic acid C2 H o3 c80h71n10o33 attempted to explain by the fol- lowing equation how the elements of protein may dispose themselves, in order to produce the compounds just described. [2 Equivts. Protein . . C80 H62 N10 024 9 „ Water ... H9 09 5 ^80 ^7 1 ^10 O3 3 Equations of this kind, though sometimes of great service in simplifying complicated chemi- cal changes, are always to be looked upon merely as representing possibilities , and should not be adopted without great caution ; much mischief has indeed already been done from the too ready credence in the truth of hypotheses which have thus been made to appear simple and striking, though really in the highest degree at variance with what further research has proved to be the truth. The action of potash on protein and its com- pounds derives additional interest from the cir- cumstance that it may afford a clue to the man- ner in which the gelatinous tissues of the body are formed from protein compounds, a problem at present very far from being satisfactorily solved. Both protid and erythroprotid are somewhat similar in composition to chondrin and glutin ; and leucin, which Mulder considers to be actually a constituent of protein, may be obtained also from gelatine, clearly showing some connection to exist between the protein and gelatine compounds ; moreover we find the gelatinous tissues formed in the herbivora, though not a trace of any analogous substance can be detected in their food. These circum- stances tend to the conclusion that the chondrin and glutin of the herbivora at least, are in some way derived from the proteinaceous matters, of the food, and Mulder has suggested that it may be owing to a change produced by the free alkali of the serum, not unlike that which I have described as the effect of the action of potash on the protein compounds. Glutin con- sists, according to that chemist, of C2 3 H , 0 N2 05, and it is easy to represent by a chemical equation how such a compound may be formed from either protid or erythroprotid. When these latter substances are formed in the labo- ratory by the decomposition of protein by potash, it is probable that two equivalents of ammonia are at the same time produced ; and we may conceive that in the living body the elements which, when not so circumstanced, unite to form ammonia, remain combined with those of protid and erythroprotid ; in that case we should have compounds containing protid phis ammonia, C13 H9 N04 + NH3 = CI3 Hn N, 04 : and erythroprotid plus ammonia, C13 H8 no# + nh, = ci3h11 n2 o5. If now we suppose that these two hypothetical substances, Cl3 H12 N, 04 and Cl3 HIt N, Os become united, the one to three equiva- lents, and the other with one equivalent of oxygen, a supply of which is always present in the arteries, we should have in the case of Protid, C13 H12 N, O, or CI3 H10 N2 Os + 2 HO ; and in that of erythroprotid C, 3 H N2 Oe or C, 3 H1? N2 Oj + HO, so that in both cases glutin might be formed. This hypo- thesis is highly ingenious and interesting, though the probability of its correctness is somewhat lessened by the circumstance that neither leu- cin, protid, nor erythroprotid, have yet been detected in the animal organism ; and more- over it is uncertain whether the alkaline re- action of the blood is owing to the presence of free alkali, or of tribasic phosphate of soda. We now come to the consideration of the natural modifications of protein, which we find composing the chief bulk of the bodies of animals, viz .fibrin, albumen , and casein. Fibrin. — This is a substance of the highest importance in the animal economy, since it is the material of which the solid framework of the muscles and some other tissues mainly consist ; and it is also found dissolved in the blood, from which it separates spontaneously after removal from the body, forming the clot or crassamentum. The following table shows the average proportion of fibrin in several animal products. 100 parts Fibrine. Blood of the hog contain 0-46 >. ox 0'37 „ sheep Beef (muscle of) 0-30 20-0 1 Veal „ 19-0 Mutton ,, 22-0 | Pork „ 19-0 1 Chicken „ 20-0 ' Cod „ 14-0 Haddock „ 13-0 Sole „ 15-0, Calf’s sweetbread (thy- mus) 8-0 Including a little albu- men. Fibrin may be obtained from lean animal flesh by cutting it into thin slices and washing with water till it is colourless ; it is, however, impossible to obtain it pure in this way, as it is always associated with fatty matters, nerves, m 3 1GG PROTEIN. and membrane. It may be obtained in a state of purity from the blood, in which, as already mentioned, it exists in a soluble condition, but remarkably prone to assume the solid form as soon as removed from the body. The blood, as soon as drawn, should be rapidly beaten up with a bundle of wires or twigs, to which the fibrin attaches itself in the form of solid amor- phous filaments, coloured red by a quantity of the globules entangled in its pores during the coagulation ; these latter may be removed by placing the coagulum in a piece of linen cloth, and washing with a stream of cold water until all colour disappears. It still contains fatty matters, inorganic salts, and a considerable ijuantity of water, all which may be removed bv drying on a chloride of calcium bath at a temperature of about 250°, pounding the hard mass in a mortar, washing with alcohol, ether, and dilute hydrochloric acid, and lastly, mace- rating in water until all soluble matter is dis- solved out, when it should be again thoroughly dried. Thus prepared, it is of a yellowish colour, hard, brittle, and, when perfectly free from fat, transparent. It is tasteless, and inso- luble in alcohol, ether, and water ; but in the latter it softens, swells up, and reassumes the appearance it had previous to desiccation. Though insoluble in both hot and cold water, it is converted by prolonged boiling, first into binoxide and eventually into tritoxide of protein, which latter is soluble in water. Most of the acids, when in a concentrated state, cause fibrin to swell up and assume a gela- tinous appearance. It was observed by Scherer that when moist fibrin is placed in an atmo- sphere of oxygen, it has the property of ab- sorbing and retaining a portion of the gas ; an effect no doubt accompanied by the formation of one or more of the oxides of protein : it is probable that a portion of the fibrin of the blood undergoes a similar change, since these oxides are always present in arterial blood both in health and disease, especially in some forms of fever, when, by an accelerated respiration, a larger amount of oxygen is introduced into the system. Fibrin and sulphuric acid. — With strong sul- phuric acid dry fibrin becomes yellowish and gelatinous, considerable heat being at the same time evolved, sufficient indeed, provided the quantity be large, to cause complete decompo- sition, when it blackens, and sulphurous acid is given off. When water is added, the gelatinous mass contracts suddenly in bulk, and the white curdy matter thus obtained consists chiefly of sulphoproteic acid, already described. Fibrin and nitric acid. — Fibrin behaves with nitric acid in a similar manner to protein, giving rise to the formation of xanthoproteic acid. Fibrin and acetic acid. — When treated with concentrated acetic acid, it almost immediately becomes gelatinous, and if water be added anil the mixture warmed, it readily dissolves, espe- cially if the fibrin be obtained from a young animal : this solution when evaporated leaves the fibrin with precisely the same properties which it had previous to dissolution. If an- other acid, as the sulphuric, be added to the acetic solution, it combines with the protein, forming generally an insoluble compound, as in the case of the sulphobiproteic acid. If the acetic acid solution be neutralized with potash, the fibrin is precipitated, but is redissolved if the alkali be added in excess. Fibrin and hydrochloric acid. — When treat- ed with strong hydrochloric acid fibrin be- comes gelatinous, and gradually dissolves, giving the solution a beautiful blue colour, which is characteristic of all the protein compounds : if this solution be diluted with water, a white precipitate appears, which is a compound of hydrochloric acid and protein. When the acid is very dilute it has the property of gradually dissolving fibrin ; and as a trace of free hydro- chloric acid is generally to be found in the stomach, it is probable that its solvent action tends to assist materially in the process of digestion. Bouchardat says that water con- taining only one two-thousandth of its weight of hydrochloric acid causes moist fibrin to become gelatinous, and eventually to dissolve, leaving only a small quantity of insoluble mat- ter, which he calls epidennose : the soluble portion he has called albuminose, but Mulder considers it binoxide of protein, which asser- tion, however, has recently been contradicted by Liebig. Fibrin and potash. — Fibrin dissolves rea- dily in a solution of potash, even when very dilute. If the solution be gently heated, the fibrin is gradually decomposed, the sulphur and phosphorus being removed, and protein remains combined with the potash, from which it may be separated by neutralizingwith acetic acid. Ammonia behaves in a similar manner, but its action is much less rapid. Fibrin readily dissolves in the gastric juice, which appears to owe its solvent action both to the organic principle pcpsine, and also to a little free hydrochloric acid in the stomach, which is derived from common salt. The same effect may be produced artificially by an infu- sion of the fourth stomach of the calf, to which a little hydrochloric acid has been added. It is curious that the presence of certain salts, as nitrate of potash and sulphate of soda, prevents the coagulation of the fibrin of the blood ; and even when coagulated, provided it be still moist, it is again dissolved by some saline solutions, as, for instance, muriate of ammonia. Moreover, M. Denis has found that if moist fibrin be digested in a solution of nitrate of potash containing a little soda, at a temperature of about 100°, it becomes gradu- ally converted into a substance in almost every respect identical with albumen, being soluble in water, and coagulable by heat. This change is most readily produced when the fibrin em- ployed has been obtained from venous blood, by allowing it to coagulate spontaneously ; ■while if it be separated by agitation, or if the blood be arterial, it scarcely experiences any alteration in the saline solution. Changes of this kind, of the several modifications of pro- tein into one another, are constantly occurring in the animal economy, and the great similarity PROTEIN. 167 of their composition must render such meta- morphoses comparatively easy. The composition of fibrin is C400 H310 N50 0120 SP, or ten equivalents of protein united to one of sulphur and phosphorus. It also usually contains from 1'3 to 2'3 per cent, of inorganic matter, chiefly phosphate and sulphate of lime, and alkaline salts. Albumen. — This important compound, so called from its constituting the solid matter of white of egg, exists in two conditions, perfectly distinct in physical properties from each other ; the one soluble and miscible with water in all proportions, as it is found in the serum and white of egg ; the other solid, and quite inso- luble in water, as in white of egg after boiling. The solid form is also met with, in a some- what modified condition, in the albuminous tissues of the body, as the brain, spinal cord, nerves, &c. The proportion of albumen con- tained in some of the animal products may be seen in the following table. 100 parts. Albumen. Blood of ox 18'6 „ hog 18’58 „ goat 19’28 „ sheep 18'35 East India isinglass 7"2 to 13 5 Egg, white of 15'5 „ yolk of 17‘47 Liver of ox, parenchyma of 20’ 19 Sweetbread (thymus) of calf 14‘0 Muscle of beef 2'2 „ veal 3'2 „ pork 2-6 „ roedeer 2’3 „ pigeon 4'5 „ chicken 3'0 „ carp 5‘2 „ trout 4-4 Brain 7'0 Optic nerve 22‘0 Albumen, in a state of absolute purity, has been but imperfectly examined. It may be prepared by the following process, recently adopted by Wurtz. A quantity of white of egg is well beaten up with about twice its bulk of water, and strained through linen to separate the cellular membrane. A solution of subace- tate of lead is cautiously added, which throws down a copious precipitate ; but care must be taken to avoid adding an excess of the preci- pitant, which would partly redissolve it. The precipitate should be well washed, and while suspended in water a stream of carbonic acid passed through it : the liquid soon becomes frothy, owing to the decomposition of the albu- minate of lead and liberation of free albumen, carbonate of lead being precipitated. The solu- tion of albumen, after filtration, generally con- tains a trace of oxide of lead, which may be separated by adding a few drops of solution of sulphuretted hydrogen, and warming the liquid till it just begins to coagulate, when the whole of the sulphuret of lead is entangled in the coa- gulum: the liquid, which after another filtration is clear and transparent, should be cautiously evaporated at a temperature not exceeding 120°, when it leaves a residue of pure albumen. Albumen thus prepared is brittle, semitrans- parent, without taste or smell, and almost colourless. When burnt it leaves a very minute quantity of inorganic residue, which seems to be quite free from alkali : this fact is important, as it tends to settle a question which has been long disputed, viz. whether pure albumen is really soluble in water, or whether its solubility is due to the free alkali with which it is usually associated. If dry albumen be digested with water in a moderately warm place it readily dissolves, but a small insoluble residue always remains. According to Wurtz a solution of pure albumen begins to coagulate when heated to about 140° ; but if it be perfectly dry it may be raised to 280° or 290° without losing its solubility. It appears to have a slightly’' acid reaction, and if digested at a gentle heat, with a solution of carbonate of soda, it dis- places the carbonic acid and combines with the soda. The albumen contained in white of eggs is composed of C40O H3 10 N50 03 „0 SP, or ten equivalents of protein plus one equiva- lent of sulphur and phosphorus ; while that obtained from the serum contains an additional equivalent of sulphur, or C400 H310 Nso 0 120 P. It is usually associated with from two to five per cent, of inorganic salts. The appearances presented by albumen with reagents are in most cases very similar to those of protein, which I have already’ described, and its solution in hydrochloric acid has the characteristic blue colour. Most of the acids precipitate it from its solution, but this is not the case with tartaric, acetic, and tribasic phos- phoric acids. Hence nitric acid is often used to detect albumen in the secretions. Another delicate test for albumen is ferrocyanide of potassium, which gives a white precipitate even with acid solutions; theferrideyanideof potas- sium gives a yellowish precipitate. The appli- cation of heat is also a good test for this principle: but as the presence of free alkali tends to prevent its coagulation, it is always ad- visable to add at the same time a drop or two of nitric acid, when, if both cause a precipitate, the presence of albumen may be considered certain: it must be remembered too that the presence of those acids which do not precipi- tate albumen, such as the tribasic phosphoric, tartaric, and acetic, also interferes with its coagulation by heat. Many of the metallic salts, when added to albumen, form insoluble precipitates, which are in most cases compounds of albumen with the acid or the base of the salt. A drop of a solution of bichloride of mercury will thus indicate the presence of albumen, even when diluted with two thousand times its weight of water; and this property of forming an insoluble compound has been taken advantage of in the treatment of cases of poi- soning with the bichloride, when the white of egg has been found of great service ; the white of one egg being sufficient, according to the experiments of Peschier, to neutralize the effects of four grains of the poison. Albumen is precipitated from its solutions by many m 4 168 PROTEIN. other substances, as tannic acid, creosote, al- cohol, and ether ; and its coagulation may also be effected by a current of voltaic elec- tricity. When taken into the stomach it is coagulated by the free acid usually present. The curious change which albumen under- goes from the soluble to the insoluble condition is but very imperfectly understood, and it is not known how far the physical state of that coagulated by heat resembles that rendered insoluble by alcohol and the other precipitants. It is said that if an egg be smeared with oil immediately after it is laid, and afterwards ex- posed to heat, the coagulation is incomplete. Coagulated white of egg readily dissolves in alkaline solutions, and is reprecipitated un- changed if the solution be supersaturated with sulphuric acid. If it be digested at a tempe- rature of about 120°, with a tolerably strong alkaline solution, the sulphur and phosphorus are separated from the protein; but if the alka- line solution be boiled, further decomposition takes place; ammonia is given off’, and leucin, protid, and other compounds are formed. If the alkaline solution in which white of egg is boiled be rather weak, it acquires, after some hours’ boiling, a smell precisely similar to that of boiled fowl. Though perfectly insoluble after coagulation, both in cold and boiling water, it appears to dissolve when heated under pressure to about 300° with that liquid, and the solution thus formed behaves in every re- spect similar to uncoagulated albumen. When exposed to the air in a moist state albumen is extremely prone to enter into putrefaction; but if dry it may be preserved unchanged for any length of time. If boiled for several hours in water it is converted into tritoxide of pro- tein, without passing through the intermediate stage of binoxide, in which respect it differs from fibrine. The ready convertibility of albumen into the other protein compounds, as well as into many other animal tissues, is well illustrated in the phenomena of incubation ; where we find all the various compounds which are contained in the hatched bird, derived more or less directly from this substance, which, together with a yellow oil and some inorganic salts, constitutes the whole of the solid contents of the egg. Casein is the form in which protein appears in the milk, where it constitutes the chief source of nourishment to the young animal, for which purpose it is admirably adapted, not only from the protein it contains, which is readily converted into fibrin and albumen, but also on account of the inorganic salts, espe- cially phosphate of lime, with which it is always associated. The proportion of casein contained in the milk of different animals varies consi- derably; and a still more striking variation is caused by the food of the animal, as may be seen in the following table. 100 parts. Casein. Cow’s milk 4‘48 „ fed on hay 3’0 „ „ turnips 3 0 „ ,, clover 4"o lOOyiar/s. Casein. Cow's milk potatoes and hay, 3‘3 to 5*1 Ewe’s milk 4-5 Goat’s milk 4'02 Ass’s milk 1*82 Woman’s milk P52 Casein is scarcely known in a state of abso- lute purity, as it is extremely difficult to sepa- rate it entirely from inorganic impurities : these consist chiefly of lime, potash, soda, and iron, combined with phosphoric, sulphuric, and hy- drochloric acids. The purest specimens pre- pared by llochleder left, when burnt, only 0'3 per cent, of incombustible ash ; but as it is generally prepared it contains considerably more, sometimes as much as 10 per cent. It appears to be insoluble in water, and owes its solubility in milk to the small quantity of potash which is always present. The best pro- cess for obtaining casein is the following. A quantity of milk is first evaporated to dryness on a water-bath, and the dry residue, reduced to powder, is boiled in successive portions of ether until the whole of the fatty matter is re- moved ; the impure curd should then be eva- porated to dryness, and the soluble part sepa- rated by digesting in water. To this solution, after filtration, alcohol is added to throw down the casein, which, however, is often still con- taminated with a little sugar of milk : this may be removed by again dissolving in water, and once more precipitating the casein by alcohol. W hen dry it resembles albumen very much in appearance, and its behaviour with reagents is in most cases very similar ; it differs from it chiefly in not coagulating when heated, and it is precipitated by all the acids, but redissolves in an excess of most of them. Sulphuric acid throws down a compound which has been called sulphate of casein; this precipitate al- ways contains a certain quantity of phosphate of lime, and it is only by repeatedly dissolving it in an alkaline solution, reprecipitating with dilute sulphuric acid, and well washing with boiling water, that it can be obtained in a state of purity. When milk or a solution of casein is heated under ordinary circumstances, a thin skin is formed on the surface, which, if re- moved, is quickly replaced by another ; this substance has never been properly examined; but as it is not formed unless oxygen is pre- sent, it is probably the result of oxidation. Casein is precipitated from its solutions by ferrocyanide and ferridcyanide of potassium, provided the solution is not alkaline, and still more perfectly if a little acetic acid is present. Lactic acid also readily coagulates casein; but the coagulation appears to be most completely effected by the lining membrane of the stomach of the young animal, an action due either to lactic acid, or, what is perhaps more probable, to the presence of pepsine. Casein lias been found in some of the animal fluids besides milk : the saliva, the bile, 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. 109 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 C400 H310 N60 0120 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- bulin 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 Iceratine, 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 1 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 whole 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 sulphur 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 floeculent precipitate when taken from the plant and allowed to stand. The readiest way of preparing it is to knead wheaten flour into a paste with water, and then wash it on a linen cloth with a stream of cold water until the w hole 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 potassium, 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 usuallj' 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 leguminosce, 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 leguminosce, 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, anti 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 : when the liquid is clear, it is decanted by means of a syphon, and slightly supersa- turated with acetic acid, which determines the precipitation of the casein in an impure state, but readily purified by washing with 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, rcdiesolving 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 alcoholic 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 required, which would 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 compounds, together with other branches of physiological chemistry : — Simon, Hand- buch der angeivandten medizinischen Chemie, of which a translation has been published by the Sy- denham Society. Liebig, Traitd de Chimie orga- nique, tom. i. & iii. Liebig's Animal Chemistry, translated by Gregory. Mulder, Chemistry of vege- table and animal physiology, translated from the Dutch by Fromberg ; and Dumas, Traite de Chimie appliquee aux arts, tom. vii. & viii. Besides these many detached papers of great value wall be found in the later volumes of the Annales de Chimie et de Physique; Annalen der Chemie und Pharmacie, by Liebig and Wohler ; Poggendorff’s Annalen der Physik und Chemie; Philosophical Transactions, Philosophical Magazine, &c. (./. E. Bowman.') PTEROPODA (Gr. irrepov, a wing, ttovs, a foot ; Fr. Pteropodes ; Lat. Mollusca pin- 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 w'as 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 {jig. 108). Hvalea (jig. 114). Pneumoderma {jig. 115). CVMBULIA. Limacina. Cleodora. Atlanta. 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 Nat. 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 cloud}', 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 Cleodorce, Hyalece, and Atlanta; may be caught ; but the larger species only come to the top when night has set in ; at which time only the Pneumodermas, the Clios, and the large Cleodorcc can be procured. Certain species indeed only approach the surface on very dark nights, as, for example, the Hyalea balantium. 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 sunrise 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 light 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 diffusion 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 support 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 wdiere 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 Clio is quite trans- parent, but after being kept in spirits of wine, its transparency is considerably diminished ; in its PTEROPODA. 172 substance, muscular 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. In 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 muscles 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 ami 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, with curious exactness, the double paddle used by the Greenlanders in navigating 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 whole of the swimming apparatus removed from the body; in which the following parts may be distinguished : — a, the anterior or Clio Borealis. Swimming apparatus detached. ( After Eschricht.') dorsal margin ; b, the posterior or ventral ex- cavation ; c c, the posterior, transparent, tri- angular lappets which bound the fin ; d d, the posterior outer border ; e e, the posterior inner border ; o, the central portion which traverses the neck ; m m 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 Cuvier’s 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. The vessel likewise called by Cuvier “ the branchial vein,” and which he regarded as re- turning the blood from the branchiae 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 to be evidently' arterial, and not venous, in its nature. With regard to the connexion which exists betwreen the fin-apparatus and the body of the Clio, it would appear that its central muscular basis passes directly through the neck, and is only attached to the surrounding parts by nerves, vessels, skin, and cellular membrane. Nervous 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 very evidently composed partly of a reddish and partly of a white nervous substance. Of the eight larger ganglia of the circum-cesophageal 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. Of 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 Cuvier, Mem. sur le Clio. PTEROPODA. 174 superficially, either from the dorsal or ventral aspect, they have the appearance of forming one elongated mass. By means of a nervous hand which connects them, the eight ganglia form a double 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 the oesophagus. In addition to the eight ganglia above men- tioned there are likewise two small nervous masses (fig. 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. Eyes. — 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. 1 13. 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. Bv 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 they are appended. Heacl-coiuls 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 contractual subgloboso- didymum est, lobo vel utroque vel a/terutro, imo quandoque neutro, antice papilla carnea (tentaculum) acuta, mucronata. Qui lobi sunt proprie prseputia duo (the head-cowls) crassa, carnea ; hemisphasrica, contractilia, basi coad- unata, e quorum interiore latere emergunt tentacula (head-cones) tria earnosa, conica, * Spicelegia, x. p. 28. aequalia quae ori utrinque adstant et contracta in praeputio tota delitescunt.” Fig. 110 (8 to 13). Anatomy of Clio. 9. Transverse section of the 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 cephalic appendages (s), and one of the tentacula (It) 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 widely 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 aredelineated on a large scale. In fig- HO. 11 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 ; buccce, Fabricius) seems, when more closely ex- amined, to be composed of two spherical parts intimately conjoined, of which the anterior (fig. 1 10. 1 1, a a) is the smaller, and the posterior (b 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 salivary 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- face, in the middle of which may be observed PTEROPODA. 175 either the tentacle {fig. 110. 10 and 1 1 , k), or the orifice (y?g.l 10. 12, 1), through which it is protruded : the two flat surfaces are separated front each other when the cowls are closed by a longitudinal fissure (p), 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 {Jig. 1 10. 11), 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 properly 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 {Jig. 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 0). Conical Appendages to the Head. — The co- nical appendages to the head (Kopfkegel, Eschricht ), when fully expanded, form a kind of star round the mouth (fg. 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 which 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 (Jig. 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 (Jig. 111. 15), and about twenty of these are enclosed in each sheath. The conical appendages to the head of a single Olio are, therefore, furnished with (20x3000x6) about three hundred and sixty thousand of the stem-supported discs in question. Fig. 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 isolated sucking disc from the above. Magnified 900 diameters. 16. The head and neck laid open by a longitudinal section, showing 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 Pneumo- 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 Clio 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. 1 10. 13, u). 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, stiff and sharp hooks {fig. 112. 22, iv), derived from a common base (.r), 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 , y) situated imme- diately behind it, in conjunction with the an- terior ganglia of the eircumoesophageal ring, and which inferiorly are connected together by strong branches of intercommunication and front which nerves radiate laterally to supply the surrounding parts. The thin ducts of the salivary glands {fig. 111. 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, i) 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 (fig. 111. 19, and fig. 112. 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. 1 12. 23, a) being far the longest ; while the an- Fig. 112 (22 to 24). Clio Borealis. 22, 23 a, 23 b. Dental apparatus, magnified 28 diameters. 24. Lateral view of the free portion of the tongue, magnified 130 diameters. ( After Escliriclit.') 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 lias 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 cylinders (,r) 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 construction 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, v), 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 hooklets 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 Mollusea. The oesophagus is, for the greater part of its length, surrounded by the two salivary glands, which extend quite into the abdominal cavity, where they 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 Acini, 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- ing fin. The course of the circulation in the Ptero- poda has not been as yet completely made out. In the Clio borealis, the heart enclosed in its pericardium is situated on the right side of the 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 base is turned towards the hind part of the body. From the apex of the heart arises a large vessel, which immediately pierces the pericardium, 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. Male 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 borealis occupy a very con- siderable portion of the abdominal cavity. N 178 PTEROPODA. They consist, first, of an Ovary with its oviduct ; secondly of the “ Madder ; ” and, thirdly, of the testis, upon which the bladder rests. The ovary (fig. 113. 27, ;j) 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 (. 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 i 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. Janies Saunders’ ex- periments were not made with any view 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 drops twice a day), 70 in the morning and 66 in the evening, and in two experiments (dose 25 drops), 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. Prout’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, giving as averages 70-91 and 70-27. PULSE. 191 Morning. Night. Difference. Dr. Knox - 68-50 64-38 4-12 - 72-00 64-39 7-61 - 79-33 63-30 16-03 - 79-25 66-66 12-59 - 94-60 65-78 28-82 Dr. Nick - 63-80 58-00 5-80 _ 6-50 Dr. Guy 64-00 54-00 10-00 Dr. Janies Saunders 60-00 56-00 4-00 Dr. Harden* 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 MALES. Age. No. of the Pulse. 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 9 15 92 85 7 18 82 73 9 22 76i 75 n STATE OF THE PULSE, MORNING AND EVENING, IN FEMALES. Age. No. of the Pulse. 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 Hold on pregnant women f) yield averages in conformity with it ; for on comparing the mean of 25 observations made * American Journal of Medical Sciences, vol. v. p. 341. t Die Geburtshiilfliche Exploration, bey Anton Friedrich Hohl. on the pulses of pregnant women in the morn- 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 sleep, 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. -j- No. viii. j 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 Ilohl 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 much 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 tins 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, 1 12, 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.^ Muller $, 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. Yalleix, Op. cit. p. 336. t See Sir David Brewster’s Natural Magic, p. 311. | 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 debility ; 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 ; Joy ;£ as 4^ to 1 ; and Eloyer as 5 to l.$ 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. f Pathology, vol. i. § 890. i 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 3'6l to 1. The extremes, in the observations on males, were 2'54 to 1, and 5'33 to 1 ; and in females, 3T0 to 1, 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 4T9 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 “ tin 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. * Vol. ii. p. 8G. VOL. IV. 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 2'61 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. Pulse. Proportion. 8 45—50 2-75 to 1 37 50—55 3-05 to 1 50 55— GO 3-31 to 1 50 GO— Go 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 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 published in the first part of Hooper’s Phy- sician’s Yade Mecum, edited by the writer early in the year 1842. o 194 QUADRUMANA. respiration in three postures of the body for the same number of the pulse: the pulse being (34, the proportions were : — standing, 2-95 to 1. sitting, 3'35 to I. lying, 4'97 to 1. Again, an average cf 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 I. 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 1. 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 tire Pulse and Respiration, by John M. B. Harden, M.D., of Liberty County, Georgia. American Journal 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 I3±- and 13, the pulse being 62 at the former period, and 64 at the latter. Calculations founded on the observations of Dr. Pennoek, 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 Females. 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 2-66 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. Bibliogkaphy. The leading monographs and essays which contain well observed facts bearing on the physiology of the pulse, will be found among the references in the foot-notes. The older works are 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. Out/.) 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 enabled to grasp objects botli 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 i Simice and the Lemurince. I. SimI-'E. Monkeys. Singes, French. Af- fen. Germ. Apen, 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 fingers 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. SimIjE VERiE, Monkeys of the Old Con- tinent, Simice catarrhince Geoffr. In general the same number of teeth as in man, viz. incisors- : canines ; molars . Nos- * 1 — 1 5—5 trils situated under the nose. a. First Genus, Simla. 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. — Simla troglodytes, Chimpanzee ; Simia Satyrus, Qrang-oetan. b. Second Genus. Hylobates Illiger. Gibbon, French. Armaffe , Germ. Langarmige Aap, Dutch. The same excessive length of the arms, which are so long as to touch the ground, 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 are 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. variegatus, H. leuciscus, the Siamang ( H . syndacty- lies') 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. Semnopithecus F. Cuv. Slanlc-aap, Dutch. Long, but slender and straight tail. 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- nopitheci 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 the Gibbons, with which they have a great analogy. Spec. — Semnopithecus entellus, S. leuco - prymnus (including Simla latibarbata, Ce- phaloptera, and S. Nestor, Benn.), S. leucomystax, S. mitratus, S. melaluphos, S. ru- bicundus, S. chrysomelas, S. maurus, S. fron- tatus, S. nemceus, S. nasicus. To these could be added, 1. S. cucullatus, but it seems but a local variety of S. leueoprymnus ; 2. S. Sia- mensis, which is a local variety of S. mitratus ; 3. S. flavimanus, which is a local variety of S. me/alophos ; 4. S. Sumatranus , local variety of S. chrysomelas ; 5. S. cristatus, variety of S. maurus. S. Muller and H. Schi.egel 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 exclusive in the Siamang, but obvious also in many other species of Gibbons. t 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. o 2 19G QUADRUMANA. other species, I followed the direction given by the said authors. d. Fourth Genus. Colobus 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 Semnopitheci and Colobi may be compared with the genus Aides 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-|- has proved, by dissection of the Colobus 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 Colobi, 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 JRodentia,. They have cheek- pouches and ischial callosities. Spec. — Colobus polyeomos, C. ferrugineus, C. guereza, 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- pitheci 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 Cercopitlieci, 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, &e., but appear on the whole to be less car- * P. S. Van Beneden, Notice sur une Nouvelle Espece de Singe d’Afrique, tom. v. n. 6. Bull, de l’Acad. Royale de Bruxelles. ■f E. Ruppell, Neue Wirbelthiere zu der Fauna von Abyssinien. Frankf. a. M. 1835 — 1840. nivorous in their appetites than either the Apes or Cynoccphali. Spec. — Cercopithecus ruber, C. JElhiops, C. fuliginosus, C. Sabceus, C. griseo-viridis, C. melarhinus, C. faunus, C. pygerythrus. To this genus are also referred the C. inona, C. cephus, C. petauristus, C. niclitans, 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 Cercopitlieci 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. pileatus, Ogilby. They 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 Cercopitlieci, 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. Geoff’roy St. Hilaire seems to have had the same views, by the formation of his genus Cercocebus, in which he places the above-named three species, and Ogilby says that he found in the Man- 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 Miopithecus. 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 Cuv. Macaque, Fr. Lapondcr-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 Cercopitlieci, with nostrils opening * Ogilby seems to agree with these views, by the formation of his genus Papio, which is much similar to my genus Inuvs. 197 QUAD HUMAN A. 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. The}' possess naked callosities, cheek-pouches, 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 Culobus and Cercopithecus, but it is not so distinct in these as in Inuus. Among the Cercopitkeci it is the most apparent in C. cyno- molgus, 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. sinicus or pile- 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. — Inuus rhesus , 7. speciosus, I. ne- mestrinus, I. maurus, I. sylvanus or ecaudatus. Amongst these the I. sylvanus is not only remarkable 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, originally from Barbary, still inhabit- ing the inaccessible precipices of the rock of Gibraltar. g. Seventh Genus. Cynocephalus Cuv. Ba- boon, Engl. Papion, Fr. Baviaan, 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 laryngeal expansions, as in the precedent genera. The 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 opening at the end, gives a hideous aspect to the Cynocephali, 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 Cynocephali less frequently assume the erect posture than any of the other Quadrumana, 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 ordinary 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, &c. 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. — Cynocephalus silenus, C. Sphynx, C. porcarius, C. hamadryas, C. gelada, C. ni- ger, C. leucophceus, 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 tail, are sufficient characters to justify this determination. The C. silenus 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 public notice by the celebrated Dr. Ruppell, is certainly a Cynocephalus nearly allied 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 Cynocephali, for example, with the skull of C. porcarius. It has the same pro- minent superciliary 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-maxillary bones. The Drill ( C, leucophceus) and Man- drill ( C. mormon) ought to be separated from the rest by a typical pre-eminence. Their cheeks are prominent, deeply ridged, and ip the Mandrill beautifully coloured. Osteology. — If we consider the bony 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 Carnivora. As I have stated elsewhere, they form an uninterrupted series, in the descending scale, beginning with the Chim- panzee, and ending with the Cynocephali. The skull of the Chimpanzee (fig, 116) is of a narrow, elongated form, slightly contracted * Recently I. Geoffroy St. Hilaire has separated the C. gelada under the name of Thecopithecus, and the C. niger under the name of Cynopithecus niger, But I am afraid that the introduction of all these new genera does not constitute an improvement for science. o 3 198 QUADRUMANA. towards the anterior part, which is, as it were, truncated. The cerebral portion, or the cra- Fig. lie. Skull of Simla troglodytes. ( A fter 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-cetan. 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 line, 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 auditorius externus in the Chimpanzee 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 Orang, 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 mem ; the principal difference is in the greater distance between the foramen caroticum 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 bimanous, and manifests the cjuadru- 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 Cynocephali 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 anchylosed to the maxillary bones in the adults of both the Chimpanzee and Orang ; but in the Chimpanzee 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. i99 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 lengthy, 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 inferiority 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. (TAnat. 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-cetan. 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 hioher, 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 (Jig. 1 16), 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 the foramen ocdpitale magnum being placed more backwards. In this and the other Gibbons a striking 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 contributes 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-cetan, and, in general, as in all the monkeys. The Semnopitheci form a sort of transition from these anthropomorphous species to the lower monkeys. Then- 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 intefc- orbital space, the single nasal bone in most of the genus, are the other characters by which the Scmnopitheci 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 o-one disappears only in the very old ones. All this is still more apparent in the Inuus sylvanus {fig. 1 19), Fig. 119. Shull of Inuus sylvanus. ( Original , 3Ius. Zool. 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 Cyno- 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 4 A. De rarioribus quibusdam Sceleti humani cum Artimalium Sceleto Analogiis. Yratis- lavite, 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 the Chimpanzee. ( After Owen.) the Chimpanzee presents but few deviations from that of the human subject. The number of true vertebrce 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 vertebrce are proportion- ally smaller in the Chimpanzee than in man, where they are enlarged in reference to his erect position. This difference from the hi- QUADRUMANA. manous type is manifested still more strongly by the narrowness and length of the sacrum, 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 vertebra, viz. the sacral and coc- cygeal, are seven in number. Of these, only 201 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. Skeleton of the Mandrill. ( Original , Mus. Zool. Soc. Amsterdam.) In the same way, the pelvis of the Chim- panzee differs from that of man in all those particulars which characterise the Quadrumana, and which relate to the imperfection of their means of maintaining the erect position. The iliac bones are long, straight, and expanded above the outside, but narrow in proportion 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 in a line with the spine, than in man ; its su- perior aperture is elongated and narrow, so that the whole of the sacrum and coccyx is visible on a front view. The tuberosities of the ischia are broad, thick, and curved out- wards. The pubic bones are broad and deep, but flattened from before backwards. In this general conformity with the quadru- manous type, there is, however, a provision for a more extended adherence of the glutaei 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 Sirniee ; and it may thence be inferred that the semi-erect position is the most easily maintained in the Chim- panzee. 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 Chimpanzee, 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, arid 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 (Jigs. 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- wtan, the Gibbons, the Semnopitheci, the Inui, to that of the Cynocephali ; but I think it necessary to make an exception for the Sia- mang, because the anthropo-morphous disposi- tion is more distinct in this ape than in any other, and even more than in the Chimpanzee or Orang-cetan. 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 vertebras ; 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 fig. 123) approach the most to that of man. The same conformity with man ap- pears in the sternum of the Siamang. It is composed of the same portions as the ster- num of man, viz. the manubrium, the body of the bone, and the xyplioidal 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-lunar incision of that of man. It is connected with a series of osseous seg- ments, and with a xyphoid appendix. In the Orang-cetan 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 , 3Ius. Vrolikl) 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 Mandrill, there is no conformity at all with the sternum of man. The manubrium is * Otto, in tlie above-mentioned pamphlet, t G. Breschet, Rech. sur differentes pieces du Squelette des Animaux Vertebre's ; Ann. de Sc. Ivatur. Aout, 1838. 203 QUADRUMANA. wanted, and the rest of the sternum composed of as many segments or sternebrae (Blain- ville), as there are true ribs. The form of the ribs has much analogy in the anthropo-morphous Apes with the ribs of man. 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-cetan and in the greater number of the other species of monkey s. They form a very ample and con- vex thorax in the Chimpanzee , the Orang-cetan, and the Gibbons, which becomes gradually more narrow ar.d compressed in the Semno- pitheci, the Inui, and Cynocepliali. In the size and length of the anterior extremities, the Orang-cetan 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-cetan 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-cetan, and the Gibbons, exhibit, as permanent conditions, proportions of the posterior extremities, which 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 man, 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-cetan 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 rvhich 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 Chimpanzee 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 pisiforme 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-cetan offers the same number of bones as in man and in the Chimpanzee ; but I have proved in my Rech. d'Anatomie comparee sur le Chimpanse, that there is in the Orang- cetan an additional bone, situated between the two series of carpal bones (fig. 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 intermediate. Its existence in the Orang- cetan, 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-cetan. Another character of the hand of the Orang- cetan, 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-cetan, can be opposed to the other fingers. The middle finger is the longest, and the metacarpal bones decrease from the index to the little finger 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 analogy with the hand of man, and approaches to the form of the paws in the Carnivora. In the Semnopitheci the thumbs offer a dispropor- tionate shortness, which scarcely surpass the rudimentary form, and prepare us in some 201 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 Semnopitheci, they are so remarkable, and, according to the views of Ogilby, helps Fig. 124. Carpus of the Orang-cetan. ( W. Vrolih.') a, scaphoid ; h, semilunar ; c, triquetrum ; d, trapezium ; e, trapezoides ; f, os magnum ; g, unci- form ; h, intermediaire bone ; i, os sesamoideum for the tendon of the abductor tongus pollicis. 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 fibula 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 patella 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 Simla:. 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 d’Anatomie comp, sur le Chimpame ; in which 1 compared the anatomical disposition and the physiological action of the foot of the Orang-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 Siamang, and in the other Gibbons, the foot approaches more to the human than in the Chimpanzee and Orang-cetan. The 205 QUADRUMANA. calcaneum 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 Reck. d'Anat. comp, sur 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 of man, in whom this muscle represents the larger subcutaneous muscles of the other mammalia. The sterno cleido-mastoidcus offers an in- cipient indication of a lower station, by the clavicular fascicle being wanting in the Inui and the Cynocepkali. In the digastricus maxilla inferioris there is, especially in the Inui and Cynocepkali, 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-tkyreoideus and hyo-glossus are united in one, in the Inui and the Cynocepkali. In the infra-hyoidian muscles, the only dif- ference from man is, that the intermediate tendon of the omo-hyoideus, which exists in the Chimpanzee as in man, disappears in the Inui and in the Cynocepkali, and that in these monkeys the inferior portions of the sterno-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 climb- 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 rkomhoideus of the Chimpanzee has the same form and situation as in man, but in the Inui and the Cyttocepkali 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 Cynocepkali, but not in the Chimpanzee, there is a conformity with the form of the large Carnivora, in the existence of the acromio-trachelien (Cuv.), acromio-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 magnus, p. brevis, subclavius, and serratus anticus magnus of the Chimpanzee, the Orang-cetan, and the Gibbons, resemble those of man. The only difference is that, accord- ing to the observations of Sandifort, th epec- toralis magnus is divided in the adult Orang- oetan into a large number of fascicles, in the intervals of which are situated the digitiform prolongations of the enormous laryngeal pouch. But in the Mandrill the pectora/is 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 leuciscus, in which the caput breve m. bicipitis takes orgin, from the insertion of the pectora/is 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 b^ observed in the extensor digiti indicts, 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 pollicis 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 Rich. d’Anat. comp., sur le Chimpanse, p. 34. 1 he 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 semitendinosus, 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 solceus 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, lumbrica/es, an abductor and adductor hallucis, a flexor brevis, adductor brevis digiti minimi, peroneeus 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 peronceus 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 tnyological 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.* 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 the Orang-cetan, of which Tiedemann has represented the basis, Nandieort the superior surface, and I a ver- tical section. (Figs. 125, 126, 127.) If we Basis of the brain o f the Orang-cetan. ( After Tiedemann .) Fig. 126. * A. Retzius, Bemerk. ueb. ein Schleuderformiges Band in dem Sinus tarsi des Menschen u. mehrere Thiere in J Muller, Arch. Berlin, Jahrg. 1841, Th. v. p. 497. W. Vrolik, Rech. d’Anat. Comp, sur le Chimpanse', p. 22. tab. v. fig. 2. Superior surface of the brain of the Orang-cetan. ( After Sandifort .) * F. Leuret, Anat. Comp, du Systfeme nerveux conside're dans ses rapports avec l’intelligence. Paris, 1839, 8vo. 207 QUADRUMAN a. Fig. 127. Vertical section of the brain of the Orang-cetan. ( After IV. V rolih .) compare these distinct views of the brain of the Orang-cetan with those of the Baboon represented by Leuret* {figs. 128,129,130), the inferiority of these to the Orang-cetan is so manifest, that it needs scarcely any further explanation. In the first instance, it appears that the brain of the Cynocephalus, and, ac- cording to the observations of Tiedemann, we could say the same for all the monkeys inferior to the Chimpanzee, the Orang-cetan, and the Gibbons, differs from the brain of man : 1. By a greater breadth in proportion to the length, and consequently by a less elliptical 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 stria- tum, 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 cornu Ammonis. 6. By the want of the eminentia digitalis ( pes Hippocampi minor). 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 Syst&me nerveux consider^ dans ses rapports avec l’intelligence, 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-cetan. 2. The larger cerebral hemispheres, which are protracted behind the cerebellum. 208 QUADRUMANA. 3. The existence of two separate corpora mammillaria, which I found also in the Hylo- bates 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 Hylobates 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 pons 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 Alan. 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 corpus callosum is not so much ex- tended backwards. About the nerves of the Monkeys, I shall but mention one very interesting modifi- cation, which I observed in the nervus 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, Nervi accessorii Willisii, Anat. et Physiol. Darmstadii, 1832. only by a less developed lobulus. 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 aorta, the superior order of monkeys, as the Chimpanzee and adult Orang-cetan, offer the same number and distribution as in Alan ; but in the Semnopitheci, the Alacaci, 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-cetan, 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 ; 5. 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. monkeys of the Old World and the human subject. Fig. 131. Laryngeal pouch of the adult Orang-cetan. ( After Sandifort.') In the organs of digestion, there is much difference to be observed in the various spe- cies of monkeys. The Apes, viz. the Chim- panzee, the Orang-cetan, and the Gibbons , offer much resemblance in these organs to those of man. The stomachs of the four young Orangs- cetan, 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 caecum 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 rudimental, 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 caecum 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 Simice and of man, but acquires a more globular form, especially in the Cyno- 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 Semnopitkeci, 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, ueber eine neue Affenart, den Cerco- pithecus leucoprymnus, in Nov. Act. Acad. Caes. Leo- pold. Carol. Nat. Curios, vol. xii. p. 2. f E. Owen, on the sacculated form of Stomach as it exists in the Genus Semnopithecus. Trans. Zool. Soc. tom. i. p. 65. The paper of Wurmb is to be found in the Memoirs of the Batavian Society. VOL. IV. 209 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 Semnopitkeci, which consists only of fruits, and it is also a repe- tition of the divisions we find in the stomach of the Pteropi, 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 Semnopitkeci. 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 guereza, and Owen * said, that in the Colobus poly comos, the sacculation of the sto- mach is produced by the same modification of the muscular fibres as in the Semnopitkeci, 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 coscum, and the length and disposition of the intestinal canal in the Colobus, equally corre- spond with those parts in the Semnopitkeci. 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- culce 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 bicorn 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 I nuns rhesus, but he observed a bifid clitoris in Cei-copitkecus sabcciis. Ac- cording to the observations of G. Breschet J. van der Hoeven and Sciiroeder van der Kolk f, the placenta of the monkeys of the * E. Owen, Proceedings of the Zoological Society, p. ix. 1841, p. 84. f Tydscheift von Natuurlyke geschiede nis en- physiologie intgegeven door J. van der Hoeven en W. H. de Yrese, Leyden 1837 — 1838, &c. & c. p. 35 7. G. Breschet, Eech. 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 Simla: comprehends those of the New World, or Cebince ( Simice platyrrhince 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. Cebinje. Monkeys of the New World. 4 The number of teeth is : incisors, — ; canines, 1 ; molars, 6—0 = 36. 1—1 C— 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. Cebince , with a prehensile tail, naked at its extremity. 1 . First Genus. Mycetes. Alouatte. Singe hurleur, Fr. Howler, Engl. 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 with the larynx, and seems to produce the loud and frightful howlings. 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. seniculus, M. fuscus, M. niger. 2. Second Genus. Ateles. Sapajou 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 Brachytele, but I think it not necessary to introduce this Quadrumanes, Mem. de l’Acad. des Sciences, s. xix. Paris. 1845. division. The species of the genus Ateles represent in America the Semnopitheci 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 fifth 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 pentadactylus, A. hypoxanthus, A. paniscus, A. arachnoides, A. fuliginosus, A. marginatus. 3. Third Genus. Lagothrix 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. canus. b. Cebince, with a prehensile tail covered with hair at its extremity. 4. Fourth Genus. Cebus. Sajou. Singe pleureur, 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 personata, C. amicta, C. cuprea , C. melanochir. One species C. sciurea, or saimiri, ought to be separated from the rest. Wagner makes * In his book des Dents des Mammiferes considers comme Caracteres Zoologiques, F. Cuvier gives the teeth of this genus as type for the Saki’s by a mis- take, which he corrected in art. Sahi noir, Hist. Nat. d. Mammif. t. iv. edit, in folio. QUADRUMANA. of it the genus Ckrysothrix. 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. Nochthnra F. Cuvier. Aotus Humboldt. Dourocouli. Differs only from the genus Callithrix 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 Nochthorce approach very much to the species of the genus Stenops, from which they differ in their internal structure. Their nails are straight, long, and sulcated. The dental 4 ] i formula is: incisors , canines -, molars 4* 1 — 1 6 — 6 - — They inhabit Brazil. t> — o Spec. — Noclithora trivirgata. 7. Seventh Genus. Pithecia. Said. The characters of this genus consist in the bushy, but short, prehensile, and long tail, the slender body, the large ears, the dense beard in some species, and the straight, but claw-like nails. Their incisor teeth are more prominent than in the genus Cebus. Brazil. Spec. — Pithecia Satanas, P . rufiventris,, P. leucocephala, P. inusta. 8. Eighth Genus. Hapale. Ouistiti. Sakui. 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 1 — 1 World, viz.32: incisors -, canines -, molars 4 l — 1 5 5 The nails, by being compressed and 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 cestuans. 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, but 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, H. penicillatus , PI. 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. ursulus, H. labiatus, II. chrysomelas, PI. rosalia , PI. chrysopygus, II. as dip us. Osteology. — If we take a general surveys 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 Lemurince, 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. The 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 Myce/es , as eminently characteristic, and, in subsequent gradation, Callithrix, Nochthora, Pithecia, and Lagotkrix. 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 Saimiri, offer- ing a typical pre-eminence, and subsequently Hapale, Cebus, and Ateles. In Mycetes (fig. 132) the forehead is ele- Fig. 132. Skull of Mycetes ursinus. (Original, 3Ius. Vrolikl) 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, Observ. de zoologie et d’ana* tomie comparee. Paris, 1811, vol. i. p. 8. 212 QUADRUMANA. which the inflated hyoid bone is situated. The same character is to be found in the genus Aides. In Mycetes, Lagothrix, and Callithrix, 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 Callithrix, 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 magma ossis sphcenoidei is yet more depressed backwards than in Hylobates. In Ccbus ( Jig. 133) the cranium is elongated, Fig. 133. Shull of Ccbus apella. ( Original , Mils. 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 lower rank. The face is not very prominent ; there are two nasal bones ; a distinct intermaxillary bone ; a rounded chin, which recedes. In Callithrix, Pithecia, and Nochthora, 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, Celnis, 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 Cebince there is a manifest inferiority to be seen in the disposition of the cervical ver- tebra, 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 inclined for- wards, and terminate in a recurved point, in the 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 iliac 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 vertebrae of the Cebince 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 only 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- tebrae, and in the monkeys with a prehensile tail the posterior vertebras become round, tubercular bones, imitating a series of small digital phalanges. The thorax of the Cebince 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 Cebus, 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 kypoxantkus, 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 little 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 Cebince 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 j * Comptes Rendus, t. xvi. n. 23, 1843, 12 Juin, p. 1236, and Description des Mammiftres Nouveaux, etc., in Archives du Museum, tom. ii. liv. 4., Paris, 1841, p. 515. t Comptes Rendus, tom.xvi.'n. 24. p.1372. 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 flex ores. 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 (I la pale rosalia), in which Cuvier and Carus state that they have found a laryngeal pouch, which, according to Cuvier, communi- cates with the larynx between the thyroid and cricoid cartilages. The second exception is the Ateles paniscus, 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 man, 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 howlings of these animals are produced. Upon the other soft parts of the Cebince 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 Semnopitheci. This peculiarity 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 andjac- chus. Recently I. Geoffroy St. Hilaire has showed to the French Academy two brains of Ouistitis, and has invited the members to verity the three state- ments which he published, viz., “l’existence de chaque cote d’un sillon profond transversal entre le lobe cerebral anterieur et le lobe moyen ; celle de quelques sillons lindaires et superficiels correspondant au trajet des vaisseaux, et l’etat lisse de la presque totahte de la surface des hemispheres.” — Comptes Rendus, n. 714, Aout, 1843, p. 280. * F. S. Leuckart, Zoologische Bruchstucke : Stuttgart, 1841, ii. p. 61. p 3 QUADRUMANA. os cliloridis , which grows larger at its anterior extremity. Rudolpiii seems to have been misled by it, in his description of a presumed hermaphroditical monkey. It is very probable that lie did not examine an hermaphrodite, but a female Ccbus capucinus.* Fig. 134. Vertical section of the liyoid hone and larynx of il Iy- cetes seniculus. ( After Sandifort.') About the embyro-genesis of the Cebinas Rudolph i published some interesting notices. He observed in the Ouistitis that the ompha- loid vesicle persists till the last period of gestation, and that there are in Hapale , My- cetes, and Cebus two umbilical veins, which unite near the liver. As an appendix to all these anatomical observations about the Cebince, I join the re- sults of the dissection of Nochtliora trivirgafa, which I made in the month of July, 1843, in the Zoological Society of London. The sto- mach ha's the transversely oblong form proper to the monkeys in general, and not the round form of the Stenops ; consequently the coscal sac is not so ample as in Stenops. The caecum 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 lobes ; they cover almost the whole cerebellum ; the fossa Sylvii is trans- verse, and very deep ; the mesial lobes are very distinct ; the asymetry between the two hemispheres is not so distinct as in Stenops, bv all which characters the brain of the Noc/i- thora trivirgata approaches to the monkeys, and differs from Stenops. The laryngeal ap- * Rudolphi, ueber eine seltene Art. des Herma- phroditism us bei einem Affe ( Simia capucina ) in Abhandl d. ICouigl. Akad. d. Wissensch. in Berlin, in J. 1816—1817 ; Berlin, 1819, 4to. Physik. Classe, p. 119. paratus has a great deal of analogy with that of man; the thyroid cartilage is large and prominent, and has almost the same form as in man. The epiglottis is much developed, particularly at its base. The arytenoid car- tilages are much elevated. The rima g/ottidis 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 papilla. 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. Lumurin'.'E. Prosimice. 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. Ololicnus Illig. Galago. The teeth of Oto/icnus are as follows, 4, . ] ] viz. incisors, — : canines, ; molars, 4 1 — 1 - — ® = 36. The inferior incisors are very 6—6 J 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 eves very large, and announce their nocturnal habits. Africa. Spec. — Oto/icnus Senegalensis, O. Mada- gascariensis. 2. Second Genus. Tarsius. Tarsier. T . 4 . 1—1 , 6—6 Incisors, — ; canines, ; molars, = S4 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 Mollucca islands, and are noc- turnal animals, feeding upon insects. Spec. — Tarsius spectrum. Third Genus. Stenops Illiger. Loris. Singe paresseux, Fr. Spoolcdier, 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. — Stenops tardigradus, S. gracilis, S. javanicus. To these ought to be added the Stenops potto Bossian, coming from the coast ox Guinea. It has a short tail and a short index. In a skull of a young Stenops potto, from the Museum at Leyden (Jig. 135), the distance Fig. 135. between the two orbits is much larger than in Stenops javanicus, tardigradus and gracilis. It is the narrowest in Stenops gracilis, broader in Stenops javanicus, still broader in S. tardi- 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 Genus. Lichanotus Illiger. Indri. 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, — =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 Avahi, Mus. Leyden (Jig. 136), Fig. 136. Skull of the Avahi. (Original, Mus. Leyden.) 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, Geoffroy St. Hilaire discovered re- presentations of certain Lemur-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 , 6—6 or rp» ; canines, ; 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 proclive 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 peculiar 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 Commf.rsonii. Seventh Genus. Lemur. Mala, Fr. Meer-lcat, 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 anil 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 a museau de renard They feed upon fruits, and inhabit chiefly Mada- gascar. Spec. — Lemur catta, L. macaco, L. ruber, L. mongos, L. albifrons, L. nigrifrons, L. rufus, L. albimanus, L. cinereus. The Lemur murinus. Mala nain ought to be separated from the other Lemurs. It seems a transition to Otolicnus. Eighth Genus. Galeopithecus. Vliegende-lcat, 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 Vespertilio but a Lemur, and that it forms in this way a tran- sition from the Lemurince to the Cheiroptera. The author of the article Cheiroptera in this Cyclopaedia 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 : incisors, - — — : canines, ; false molars, 4 l—l ; true molars, — — =34. The form of 2—2 4—4 these teeth 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. T£he 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 lamince. The incisors and false molars of the lower jaw are detached. Spec. — Galeopithecus vanegatus. Osteology. — The considerations upon the skeleton of the Lemurince ought to be con- Sltull of Galeopithecus variegatus. ( After Waterhouse .) 217 QUADRUMANA. nected with those upon the Cebince, in which I said that the form of the bony framework passes gradually and in a descending line into the form of the Lemurincs, 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 Lemurincs, 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, lAchanotus, Stenops, Otolic- nus, and Lemur, and forming there a boun- dary for the open orbit. In all the Lemurincs 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 intermaxillar 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 (Jig. 138) and Lemur, there is a regular oval Fig. 138. Skull of the Cheirogaleus Commersonii. ( Original, Mus. Ley deni) 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 Cebince. In the vertebral column the cervical vertebrce are seven in number. The anterior vertical ridges of the transverse processes, in the pos- terior cervical vertebra1, 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 Stenops. The spinal processes offer the opposite direction which is proper to the inferior orders of Mammalia, excepting in Ste- nops and Lichanotus, in which they are all inclined backwards. The bodies of the dorsal vertebras 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 vertebra 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 , Otolicnus, 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 - rince. 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 Sternebrce 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 Lemurincs 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, Recti. d’Anat. Comp, sur le Genre Stenops dTUiger, in N. Verhand. d. eerste classe van het Koninkl. Nederl. Instituut. Amsterdam, D. ix. 1843. 218 QUADRUMANA. brachium is less firm, by which the hand acquires a great deal of mobility, and can be inclined, as I have often observed, not only outwards, but also backwards. With regard to the posterior extremities, the principal deviation is offered 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 Stenops 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 Lemurince. 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. digastricus 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-hyoideus , which is wanting in many large Mammalia, but exists in the monkeys, and as my dissection has proved in the Dasyurus , the Ursus arctos, the Pteropus, and the Opossum. This muscle is also one of the links connecting the genus Stenops 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 magnus 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 biceps and brachialis interims is interesting, because it proves that the genus Stenops, and probably the other Lemurince, 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 ol 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 biceps, and an additional proof that the genus Stenops forms a transition from the Quadrumana to the Carnivora. In the antibrachium the prona- tores and supinatores are very strong. The Jlexores are the radialis and ulnaris interims, with the palmaris longus. The extensores are the radialis externus longus et brevis, with the ulnaris externus and the extensores of the fingers. For the flexion of the fingers, there is a rudimental flexor superflcialis , which is wanting in the Carnivora, and which exists, on the contrary, in the Quadrumana. Instead of the abductor magnus and extensor brevis pollicis 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 Mandrill, and more distinctly in the Jnui. Besides this the thumb of the Stenops pos- sesses a flexor brevis, an abductor brevis, and an adductor pollicis. 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 interims and attached to the small trochanter. The sartorius has an oblique 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 pectinceus, 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 Bradypus 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 seini-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. Th eglu- tceus maximus has a large insertion on the thigh, and is inserted very much downwards. On the anterior crural surface there are a tibialis anlicus, an extensor magnus and brevis digitorum pedis, and extensor brevis hallucis, which has a very oblique direction, and a per- onceus magnus and brevis. As regards the Jlexores, I have only to mention the union of the flexor magnus hallucis with the flexor mag- 219 QUADRUMANA. nus quatuor digitorum 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 lumbrical muscles. Instead of a flexor brevis there are but small tendons, which bifurcate for the passage of the tendons of the flexor magnus hallucis, and dexor magnus quatuor digitorum pedis. The tibialis posticus 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 Stenops in his climbing motions. Neurology. — The encephalon of the Lemu- rince is only known by the dissection of the Lemur mongos and of the Stenops javanicus and tardigradus. Science is indebted for the first to Tiedehiann, and for the two last to Sciircedkr van der Kolk and to myself. 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 described 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 (fig. 139), the triangu- lar form of the anterior lobes, the few convo- Brain of Stenops tardigradus. ( After IV. Vrolih.') lutions,the shallow anfractuosities, the scarcely indicated fossa Sylvii, the not prominent pons Varolii, the very thick cerebral peduncles (crura cerebri), the want of corpora candicantia, the short corpus callosum. 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 Lemurinae are nocturnal, and see very well in almost profound obscurity, as is proved by the observations of F. Cuvier, in the Lemur murinus. The ears of Stetwps are very large ; the concha deep, the tragus and antitragus ele- vated, and instead of anthe/ix 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 plane form ; 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 coining from the arcus aortcE is as in the plurality of Mamma- 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 Gaimard ; 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 Bradypi, by Schrclder van der Kolk and Otto, they consist not only of arteries, but also of Veins 5 and that, by dividing in branches, these ramifications become smaller and smaller, and composed of a less number of vessels (fig. 140). Splanchnology.- — The stomach hasinN/c- nops a rounded, almost globular form, in which the cardia is near to the pylorus, and the ccecal 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 Lemurince, and already pre- Fig. ldO. and in the apes. The ccecum is very large, and the colon has also a great extension. The colon is in general larger in the Lemurince than in the Simla;. It is said by Cuvier to want cells. In Lemur murinus it is short and ample. Duver- noy and Schroeder van der Kolic describe alternating constrictions and expansions in the intestinal canal of Stenops, 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 epiglottis. All these points are proofs of imperfection, by which may also be explained the total want of voice in Stenops. The hyoid bone is different from the hyoid bone in the monkeys, and ap- proaches to that of the inferior Mammalia. Its body is a transverse arch, slender, and united at the two extremities with the two pairs of horns. The anterior horns are 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. HI. 221 RADIAL AND ULNAR ARTERIES. 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 U %• 141). 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 Lemurince 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 Cebus much larger than the modern species. Bibliography. — Maximilian, Pr. zu Wied., Beitr. z. Naturgeschiehte von Brasilien, Weimar, 1826, B. 2. R. P. Lesson, Spec, des Mammiferes hi- xnanes et quadrumanes, Paris, 1840. J. Geoffroy St. Hilaire, Desc. des Mammiferes nouveaux 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 Mammalogie, Leyde, 1835, tom. 2. 12e. Monographic sur le Genre Singe, Simia Linn. Blainville, Osteographie, ou Description ico- nographique comparee du Squelette et du Sysfeme dentaire des Cinq Classes d’Acrimaux vertebre's r^cents et fossiles. Ogilby, 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 vergleiehenden Anatomie der Affen, 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. Natuurkundige 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 Satyrus') in Yerhandelingen over de Natuurlyke Geschiedenis der Nederlandsche over- seesche Bezittingen, Leiden, 1840. Herman Schleget en Sal. Midler Bydragen tot de Natuurlyke Historie van den Orang-oetan in the same Memoirs. E. Tyson, Orang-outang, sive Homo sylvestris, or the Anatomy of a Pygmie compared with 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, Yier Abbildungen des Schedels der Simia Satyrus von verschiedenen Alter., Marburg, 1838. A. Vosmaer, Beschryving van de zoo zeldzame als zonder- linge Aapsoort, genannd Orang-outang van het Eiland Borneo, Amsterdam, 1778. I). L. Osamp, Naauwkeurige Beschryving van den grooten en kleinen Orang-outang, Amsterdam, 1803. W. Vrolik, Eecherches d’Anatomie comparee sur le Chimpanse, Amsterdam, 1841. F. Tiedemann, leones Cerebri Simiarum et quorundam Animalium rario- rum, Heidelberg, 1821. F. Tiedemann, Him des Orang-outang's mit dem des Menschen verglichen in Zeitschrift f. die Physiologie, Darmstadt, 1827 ; 2 B. p. 17. C. A. Rudolphi, Ueb. d. Embryo d. Affen u. einige andere Saugethiere, Berlin, 1828. T. S. Leuckart, Ueb. die Bildung d. Gesleehtsor- gane insbesondere der aiisseren einiger Affen in Zoologische Bruchstiicke; Stuttgart, 1841, ii. p. 37. A. W. Otto, Ueb. eine neue Affenart 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. Maid, 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 Keimtniss der Gattung Tarsius, Berlin, 1846. I regret that this very valuable work was not published when I wrote my article in 1843. (IV. Vrolik 0 RADIAL AND ULNAR ARTERIES. (Arteres radiate et utnaire — Speichenpulsader und E/lenbogenpulsader.') — 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 in 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 pollicis, 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 the 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- pinator longus, and whose inner side is the pronator teres. In the lower portion it oc- cupies 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. ( h .) 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, anil 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 223 RADIAL AND ULNAR ARTERIES. 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.) In the palm. — 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 otf its magna pollicis and radialis indicis branches, it now crosses the palm as the deep palmar arch, or “ palmaris 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. (1.) Arteria radialis recurrent. — This large branch is given off 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 superfcialis voice, 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 terminations of the an- terior interosseous artery. It supplies the carpal bones and the articulation. (4.) The arteria dorsalis carpi radialis, or posterior carpal branch, is considerably larger than the preceding, and is given off 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 different 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 entering the palm. Thus an arteria dorsalis pollicis 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 fourth 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 dorsalis polli- cis. The arteria magna seu princeps pollicis 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 pollicis, 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 posterior 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 slip 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 ic arrives at the point to which we conducted the superficialis 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 thumb 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 arteries recurrentes ulnares anterior et 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 brachial is anticus, and corresponding to the elbow joint which it partially supplies ; its superior termination inosculates 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 digitorum, 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 metacarpi 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 freely 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 tw'o 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. A very constant branch, though usually only 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 artery 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 arterice carpi ulnares 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 case 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 carpus. In addition to the Q 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 band. Tlie communicans ulna; 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 digiti, 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 supplying the ulnar side of the little finger, and the remaining three corresponding 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 ; lying 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 termination, 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 uniting 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 lust 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 actual numbers, 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. Varieties 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 op- posite limb the distribution is the usual one. The most frequent of the two is the high 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, bears yet the name of brachial, since it generally possesses the ordi- nary relations and distribution of the latter vessel. Under 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 the 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 venaesection 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 dilated 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 ; bnt 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 ulnar communicating, which is generally little inferior in size to the radial contribution. 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 volte, 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 considering 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 much more pronounced posteriorly.* In the hand, two arches which are continuations of the larger vessels occupy its surface of flexion, at diffe- 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 run 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 development either of one of these longitudinal branches, or ol 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 finally, 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 important 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- * LTnless we considered the deep palmar arch as the anterior half of the carpal ring, a view which the comparative infrequency of the minute “ante- rior carpal arch ” would almost allow of. j- It may be urged against such a generalization, “ that it would scarcely include the varieties of those vessels which 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, would again include them in the category of dilated inosculations. Q 2 228 RADIO-ULNAIl 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. The 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 usuall}' adopted is there any- 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. Flere, 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 pressure, while its beats are associated with unusually little ex- pansion, though they strike the fingers with more force. (William Brinton). RADIO-ULNAR ARTICULATIONS. ( Articulations radio-ulna ires— Verbindungen des Ellenbogenbeins mit 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 articulation — 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, m 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 radius 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 theradius 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 — ap 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 depression 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 Q 3 IIADIO-ULNAR ARTICULATIONS. 230 of these articular facets so as to result in a species of capsule. The triangular fibro-cartilage 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 like 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 synovial 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 movements 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, would 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- moid 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 supination. — 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 certainty 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 REN. 23! muscles that effect pronaticn, 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 affecting 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 extremity 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, mutatis 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 (Or. vs, within the capsule, a a, Some rounded particles, which are sometimes seen in considerable numbers, either on the surface or in the wall of the vessels c. The basement membrane of the capsule, b m, beyond the termination of the ciliated epithelium appears quite naked. Magnified 200 diameters. I am not aware that ciliary motion has been detected in the kidneys of Mammalia or Birds. 1 shall presently show that in certain fishes and reptiles the cilia are not confined to the situation in which they were first discovered by Mr. Bowman ; but that they exist through- out the greater part, if not the whole length, of the uriniferous tubes. It appears desirable to allude here to some observations which have been made since the publication of Mr. Bowman’s paper, and to inquire how far certain statements which have been opposed to his account of the Malpighian bodies are worthy of consideration. It is not my intention to occupy time and space, by giving a history of all the contradictory opi- nions which this subject has elicited. It may be fairly inferred that inability to detect ciliary motion within the Malpighian capsule, or to verify any observation in reference to which several competent authorities are agreed, is the result of some defect in the microscope employed, or in the eye or mind of the ob- server. Objections have been made to two' parts of Mr. Bowman’s description ; first, to his account of the relation which the Malpighian capsule bears to the basement membrane of the tube and to the blood-vessels; and, secondly, to his statement that the Malpighian capillaries lie uncovered within the capsule. Bidder* made his observations on the kid- ney of the male triton (Triton tseniatus). The anterior part of the kidney of this animal is exceedingly well adapted for the investigation in question, since it is very thin and transpa- rent, and is thus fitted for microscopical ex- amination without further artificial preparation by tearing or other means. Bidder believes that the vessels do not perforate the capsule to enter its cavity, as described by Mr. Bow- man ; but he considers the basement membrane to be introverted so as to form a covering for the vessels and a complete partition of a semi- lunar form between the cavity of the tube and that of the Malpighian capsule. 1 have exa- mined the kidney of the triton with great care, and have satisfied myself that Mr. Bowman’s account of the perforation of the capsule by the vessels is strictly correct, and that there is no partition, but, on the contrary, a free communication, between the cavity of the capsule and the orifice of the tube. When the vessels are distended with blood, they almost fill the capsule ; on the contrary, when they are empty, they shrink into a small com- pass. I have examined them under both conditions, and could never detect any ap- pearance of a membrane reflected over them. The free communication between the cavity of the capsule and the orifice of the tube is sufficiently shown by two phenomena which I have repeatedly witnessed : first, when the cilia are in action, the liquid filling that part of the capsule which is unoccupied by the vessels is freely propelled from the cavity of the capsule into the tube; and, secondly, when water is added to the specimen, loose particles of epithelium from the tube are often driven into the capsule, until they fill that part of its cavity which is not occupied by the collapsed blood-vessels. Dr. Gerlach* describes and figures the Mal- pighian capsule as being not a blind termi- nation of the uriniferous duct, but a lateral diverticulum of the same structureless base- ment membrane which forms the duct ; and he believes that the capsule communicates with the duct by means of a short neck. It is not impossible that there may, in some rare instances, be a diverticulum from a tube as represented by Gerlach ; but as I have never yet seen such a mode of connexion between a tube and a capsule, and as 1 have seen numberless instances of tubes terminating directly in the dilatation which constitutes the Malpighian capsule, I do not hesitate to de- clare my decided conviction that Mr. Bow- man has correctly described the structures in question. f With reference to the second point above alluded to, namely, to Mr. Bowman’s state- ment that the Malpighian capillaries lie un- covered within the capsule, the observations of Gerlach deserve more consideration. He states that when the Malpighian capillary net- work is examined after the capsule has been entirely detached from it, it may be seen in its whole extent covered by a thick layer of nucleated cells, which are continued from the inner wall of the capsule upon the Malpighian vessels ; so that the latter lie introverted with- in a layer of cells like the intestine within the peritonaeum {Jig. 1 60.) ; and he supposes that the secreting structure of the Malpighian bodies differs from the ordinary structure of glands * Muller’s Arcliiv. 1845. f Dr. Gerlacli’s opinion of the manner in which the tubes are connected with the Malpighian cap- sules, is founded upon appearances which he ob- served after injecting the urinary tubules from the pelvis of the kidney. He believes that in this man- ner he succeeded in filling the Malpighian capsules as well as the tubes, and that, too, as he says, after he had failed in filling these parts by injection of the Malpighian vessels from the artery in the man- ner before described. ( Vide ante, p. 241.) On a careful consideration of the drawings by which Dr. Gerlach’s paper is illustrated, there seems reason to believe that the appearances which he describes as Malpighian bodies may result from a sudden bulging of the tubes produced by forcible distension with the injected material. (See Muller’s Arcliiv., 1845, plate 13.) It cannot be a matter of surprise that a forcible injection of the tubes from the pelvis should give rise to unnatural appearances in these structures; whereas a slow infiltration of injection from the ruptured Malpighian vessels, or an equally slow extravasation of blood during life, while it fills the capsules and the tubes, leaves these parts as nearly as possible in their normal condition, and affords the most satisfactory evidence as to the na- ture of their connexion with each other. Muller’s Arcliiv. 1845. only in the absence of the basement mem- brane between the vessels and secreting cells. Dr. Gerlach’s figure (fig. ICO.) exhibits an Fig. ICO. Malpighian tuft of capillaries covered with small transparent nucleated cells. ( After Gerlacli.') appearance which even* one must have seen in the tuft of vessels extended from the cap- sule, but which fails to establish the existence of this epithelial investment of the tuft ; for at the border of the figure the wall of the capillaries is seen actually bare, as described by Mr. Bowman. The fact, however, seems to be, that there do exist, here and there, upon the outside of the capillaries of the tuft, nu- cleated particles, of an extremely delicate nature, the nuclei sometimes lying isolated in the fork of two vessels, and the substance ot the cell not expanding into a continuous co- vering of the whole tuft. It is possible that these nucleated particles may be rather the nuclei belonging to the capillary wall, than a modified representation of the epithelium of the tube. It is at least certain that they lie sparingly upon the individual vessels of the tuft, and do not form a membranous invest- ment of it as a whole. Mr. Bowman showed me these particles, as I have now described them, some years ago. Their existence does not affect the substantial accuracy of his ac- count of the anatomy of the tuft, nor his view of its special share in the secretion of urine. Having thus briefly alluded to certain parts of Mr. Bowman’s description of the Malpig- hian bodies, the correctness of which has been questioned, and having shown, as I hope, that only in one minute part of his clear and accurate account of their structure is any mo- dification required, we may proceed to trace the blood-vessels in their course from the Malpighian bodies. The blood, leaving theMalpighian tufts, is conve3'ed by their efferent vessels to the great renal reservoir, the capillary plexus surround- ing the uriniferous tubes (figs. 152. 154. and 155.). The vessels lie in the interstices of the tubes, and everywhere anastomose freely, so that throughout the whole organ they con- stitute one continuous network, lying on the outside of the tubes, in the substance of the matrix, and in contact with the basement membrane. This plexus is intermediate be- tween the efferent vessels of the Malpighian bodies and the veins. The efferent vessels of the Malpighian bodies are always solitary, and never inos- culate with one another : each one is an iso- lated channel between its Malpighian tuft and the plexus surrounding the tubes. They are formed by the union of the capillary vessels of the tuft, and emerge from its inte- rior in the manner already explained. After a course of variable length they open into the plexus. Their size is various. In general they are smaller than the terminal twig of the artery, and scarcely, if at all, larger than the vessels of the plexus into which they discharge themselves. But where the Malpighian tuft is larger, the efferent vessel is usually large also, and divides into branches before en- tering the plexus. This is eminently the case with those situated near the base of the me- dullary cones, where the medullary and cor- tical portions of the organ seem to blend. The efferent vessels from these large Mal- pighian bodies are often three or four times the diameter of those of the plexus, and take a course towards the pelvis of the kidney between the uriniferous tubes (fig. 154. 1 .). They were formerly mistaken for tubes. They branch again and again in the manner of arteries, and form the plexus with long meshes, which invests this part of the tubes. Some of the veins springing from this plexus form the well-known network on the nipple- shaped extremities of the cones, around the orifices ; and thence take, with the remainder, a backward course, likewise parallel to the tubes, to empty themselves into various branches that lie about the bases of the cones. The arrangement of the venous radicles on the cortex and on the surface of the kidney has been already described (fig. 145). The veins from the capsule and surrounding fat join the renal vein in some part of its course. It is probable that the capillaries of the vasa vasorum, within the substance of the organ, pour their blood into the capillary plexus sur- rounding the tubes, as those of the hepatic artery do into the portal hepatic plexus of the lobules of the liver. Thus, there are in the kidney two perfectly distinct systems of capillary vessels, through both of which the blood passes in its course from the arteries into the veins : the first, that inserted into the dilated extremities of the uriniferous tubes, and in immediate con- nection with the arteries ; the second, that enveloping the convolutions of the tubes, and communicating directly with the veins. The former, which may be called the Malpighian capillary system, is made up of as many parts as there are Malpighian bodies. These parts are entirely isolated from one another; and as there is no inosculation between the arterial branches supplying them, the blood enters each in a direct stream from the main trunk. Each separate part also of this system has but one afferent and one efferent channel, and both of these are exceedingly small, compared with the united capacity of the capillary tuft. The artery in dividing dilates ; then follow branches which often exceed it in size, and which gradually break up into the finest. The efferent vessel does not usually even equal the afferent, and in size is often itself a capillary. Hence wrould arise a greater retard- 250 REN. ation of blood in the tuft than occurs pro- bably in any other part of the vascular system ; a delay that must be increased by the tor- tuosity of the channels to be traversed. The other system of capillaries, or that surrounding the uriniferous tubes, corre- sponds, in every important respect, with that investing the secreting canals of other glands. Its vessels anastomose with the utmost free- dom on every side, and lie on the deep sur- face of the membrane that furnishes the secretion. Mr. Bowman has applied the term “portal system of the kidney” to the series of vessels connecting these two, on account of the close analogy it seems to bear to the vena porta, intervening, like it, between two capillary net- works, the first of which answers to that in which the vena porta originates, and the second to that in which the vena porta ter- minates. The capillary plexus surrounding the tubes differs, therefore, from that of other glands, and agrees with that of the liver, in its receiving blood that has previously tra- versed another system of capillary vessels. The correctness of the analogy which Mr. Bowman has drawn between the circulation of the kidney and that of the liver is very beautifully shown by his observations on the kidney of the boa-constrictor, an animal which may be regarded as the type of those in which, besides the renal artery, the kidney receives a portal vein derived from the hinder part of the body.* Mr. Bowman thus de- scribes the organ in question : — “ The kidney of the boa, being composed of isolated lobes of a compressed reniform shape, displays all the points of its structure in peculiar sim- plicity and beauty. At what may be termed the hilum of each lobe, the branches of the vena porta and duct separate from those of the renal artery and emulgent vein ; the two former spreading side by side, in a fan-like form, over the opposite surfaces of the lobe, while the two latter enter its substance and radiate together in a plane midway between these surfaces. The lobe is made up of the ramifications of these four sets of vessels, in the following mode {fig. 161.). Each duct, as it runs over the surface, sends down a series of branches which penetrate in a pretty direct manner towards the central plane. Arrived there, they curl back, and take a more or less retrograde course towards the surface, and, finally, becoming more convoluted, terminate in the Malpighian bodies, which are all situated in a layer at some distance within the lobe, parallel to the central plane, and nearer to it than to the surface. The ducts never anastomose. The artery subdivides into ex- tremely minute twigs, no larger than capil- laries, which diverge on either hand and enter the Malpighian bodies. The efferent vessels are of the same size as the afferent, and, on emerging, take a direct course to the surface of the lobe, and join the branches of the vena porta there spread out. The * Vide ante, p. 232-3. branches of the portal vein on the surface send inwards a very numerous series of twigs Fig. 161. Plan of the arrangement of the elements of the kidney, in the boa constrictor, by Mr. Bowman. a, arterial branch in the centre of the lobule, sending afferent twigs to the Malpighian bodies on each side. The efferent vessels are seen running to the branches of the portal vein, p v, pv, on the sur- faces of the lobule. The plexus surrounding the tubes is seen at p, running from the portal vein to the emulgent vein, e v, which lies in company with the artery in the centre of the lobule. The urinife- rous tube, t, is seen commencing in the M. body, and passing to the branch of the ureter, u r, u r, at the surface of the lobule where it accompanies the portal vein. The M. bodies are seen diminishing in size, as the tubes become shorter towards the thin edge of the lobule h. of nearly uniform capacity, and only a little larger than the vessels of the capillary plexus, in which they almost immediately terminate. This is the plexus surrounding the uriniferous tubes. It extends from the surface to the central plane of the lobe, and there ends in the branches of the emulgent vein.” “ Thus the efferent vessels of the Malpighian bodies are radicles of the portal vein, and, through the portal vein, empty themselves, as in the higher tribes, into the plexus surround- ing the uriniferous tubes. The only real difference between this form of kidney and that of Mammalia is that there is here a vessel bringing blood that has already passed through the capillaries of distant parts, to be added to that coming from the Malpighian bodies, and to circulate with it through the plexus surrounding the tubes. The efferent vessels of the Malpighian bodies run up to the surface, in order to throw their blood through the whole extent of the capillary REN. 251 plexus; which they would fail to do if they entered it in any other part.” “ I have described the renal artery as being spent upon the Malpighian bodies ; but in the hilum of the lobe it gives off, as in the higher animals, a few slender twigs to the coats of the excretory ducts, and of the larger vessels. The capillaries of these twigs are easily seen, and, in all probability, dis- charge themselves into the branches of the portal vein.” It will appear on referring to the plan (Jig. 1G1.), that there is a direct relation between the size of the Malpighian bodies and the width of the lobe. At the apex of the lobe, where the uriniferous tubes are corn, paratively short, the Malpighian bodies are of small size, while at the base of the lobe, where the tubes are longer, the Malpighian bodies present a corresponding increase of size. It will presently be seen that this and other facts in the anatomy of this form of kidney, alford very important evidence as to the nature and office of the Malpighian bodies. Mr. Bowman thus draws a comparison be- tween the circulation through the kidney of the Boa and that through the liver : — “ The circulation through this form of kidney may be aptly compared with that through the liver, as described by Mr. Kiernan in his invaluable paper on that gland. The plexus surrounding the tubes corresponds with the portal-hepatic plexus, which, in the lobules of the liver,invests the terminal portions of the bile-ducts. Both these plexuses are supplied with blood by a portal vein, derived chiefly from the capillaries of distant organs, but in part from those of the artery of the respective organs them- selves. The only difference seems to be, that, while in the liver the branches of the artery are entirely given to the larger blood- vessels, ducts, &c., in the kidney a few only are so distributed, the greater number go- ing through the Malpighian bodies, to per- form an important and peculiar function. In both glands, however, all the blood of the artery eventually joins that of the portal vein. The emulgent vein of the kidney answers to the hepatic vein of the liver.” “ The comparison between the hepatic and the renal portal circulation may be thus drawn in more general terms. The portal system of the liver has a double source, one extraneous, the other in the organ itself ; so the portal system of the kidney, in the lower tribes, has a two-fold origin, one extraneous, the other in the organ itself. In both cases the extra- neous source is the principal one, and the artery furnishing the internal source is very small. But in the kidney of the higher tribes the portal system has only one internal source, and the artery supplying it is proportionably large.” Mr. Bowman has ascertained that in all the vertebrate classes the Malpighian bodies have essentially the same structure ; the capsule being formed by the dilated extremity of a uriniferous tube, into which a single mass of blood-vessels is inserted. But in some orders of animals there are modifications which merit notice. The most considerable of these re- gard the size of the Malpighian bodies. The following table from Mr. Bowman’s paper ex- hibits their size in a few species, and subjoined to each measurement is that of the tube soon after its emergence. It will be seen that the diameter of the tubes varies far less than that of the Malpighian bodies. Table of the Diameter of Malpighian Bodies, and of the Tubes emerging from them, in fractions of an English inch. Diameter of Malpighian Bodies. Diameter ofTubes. Max. Mean. Min. Man Wo 1 Tor 1 111 1 750 Badger l ToJ Til I T3o I 116 Dog 120 T33 156 600 Lion 1 70 80 I 90 1 512 Cat 1_ log 200 1 250 1 680 Kitten 1 •105 1 200 1 3T2 1 Tooo Rat I T3o T5o l 205 l 7T6 Mouse 1 220 253 1 512 1 *770 Squirrel I 207 1 770 Rabbit 1 l5(j 1 623 Guinea Pig 1 208 1 600 Horse 1 55 1 70 1 90 1 776 Parrot 1 730 1 tn 1 600 L'-"7(j0 Tortoise 1 270 1 780 Boa 1 250 ibo l 570 1 570 Frog I 250 Eel ... I 207 According to Professor Muller* the kid- ney of the myxinoid fishes has a very simple structure. Before the publication of Mr. Bowman’s paper Muller described the kidney of these fishes, as consisting of a long ureter extending on each side of the intestine, and sending off at intervals a small sac which terminates in a second closed sac, the junction of the two sacs being marked by a constric- tion. In the cavity of the closed sac there is a globular tuft of vessels, which is free on all sides except at one point, where the vessels pierce the investing capsule {Jig. 162.). Prof. Muller, from a comparison of his own obser- vations with those of Mr. Bowman, infers that the short tubes proceeding from the ureter in these fishes are analogous to the uriniferous tubes in the more highly organised kidneys, while the closed sac at the extremity of the tube is analogous to the Malpighian capsule ; so that each renculus in the myxinoid fish consists of an exceedingly short uriniferous tube terminating in a capsule, in which is sus- pended a globular tuft of vessels. The arte- rial branches which come directly from the aorta terminate, as in the higher animals, by piercing the capsule and forming a globular tuft within it. Miiller had not an opportu- nity of tracing the exact distribution of the * Untersuchungen uber die Eingeweide der Fische. Berlin, 1845. 252 REN. blood after leaving the capsule, but lie thinks it probable that the veins form a plexus on Fig. 162. 2 1 a 1. The anterior extremity of the kidney of the Bdellostoma Forsteri , of the natural size. a, the ureter ; b, a short uriniferous tube proceed- ing from it ; d, the capsule at the extremity of the tube ; /, the arterial branch entering the capsule ; <7, the anterior blind extremity of the ureter. 2. Distribution of the blood-vessels in the kidney of the Bdellostoma Forsteri. A, the ureter ; B, a uriniferous canal proceeding from it ; C, section of the capsule covering the blood- vessels; D, the vascular mass injected; a, the affe- rent vessel of the same ; b, the efferent vessel ; c, an artery unconnected with the vascular mass distri- buted to the ureter ; d, a branch of the renal vein. This figure is slightly magnified. ( After i! duller.') the outer surface of the tubes. It is to be regretted that Muller has not given some account of the microscopic appearances pre- sented by the inner surface of these tubes, since without some observations on this point, and particularly with reference to the charac- ter of the epithelium, it is not possible to form a definite notion as to the exact nature of the parts in question. Epithelium. — In examining the epithelium of the kidney, it will be convenient to com- mence with that of the Malpighian bodies, and thence to trace this structure through the tubes into the pelvis and ureter. It is scarcely possible to overestimate the importance of a careful study of the epithelial cells in different parts of the kidney, since accurate observations upon this point must form the basis of an exact knowledge of the physiology of the gland, and of the pathological changes to which it is liable. Epithelium of the Malpighian bodies.— M1 ith reference to the epithelium of the Malpighian bodies, it will suffice to recapitulate here what has already been fully detailed in speaking of the structure of these bodies. The epithelium of the Malpighian bodies consists of two dis- tinct portions ; first, that which covers the vessels ; and, secondly, that which lines the capsule. The vessels of the Malpighian tuft appear to have in many instances a more or less complete investment of small, delicate, and transparent nucleated cells. {Fig. 160.) These cells differ entirely from those on the inner surface of the capsule, as well as from those which line the urinary tubes. The epi- thelium covering that part of the capsule which is contiguous to the orifice of the tube is very transparent, and clothed with vibratile cilia. This ciliated epithelium covers about one-third of the inner surface of the capsule ; beyond this point the cilia cease, and the epithelium is of excessive delicacy and translucence {figs. 158. and 159.), while in many instances it is impossible to detect the slightest appearance of epithelium beyond the line where the cilia cease. The cilia in this situation have been observed only in reptiles and fishes, but they probably exist in all classes of Vertebrata. . Epithelium of the uriniferous tubes. — The epithelium of the uriniferous tubes presents itself in two distinct forms, the one kind exist- ing in the convoluted tubes of the cortex, and the other in the straight tubes of the medullary cones. The epithelium in that part of the uriniferous tubes immediately continuous with the Malpighian capsule, presents the same characters as that which covers the contiguous portion of the capsule, consisting of delicate transparent particles, which in fishes and rep- tiles are furnished with vibratile cilia. In the remaining portions of the tubes which intervene between the neck of the Malpighian capstdes and the bases of the medullary cones, the epithelium presents itself under the form to which the term spheroidal or glandular is commonly applied.* The particles are of a more or less rounded form, and are thus distinguished from the flattened cells of the lamelliform or scaly variety of epithelium. (Fig. 163.) They usually form a single lajer Fig. 163. a, portion of a convoluted tube from the cortex ot the kidney, showing the appearance of its epithelium. b, portion of a straight tube with its epithelial lining from a medullary cone. Magnified 200 dia- meters. * Vide article Mucous Membrane. REN. 253 covering the surface of the basement mem- brane. They are granular and opaque, and appear to contain a considerable quantity of solid matter. The cell wall is very delicate, and when water is added to the specimen, the cells frequently fall in pieces very rapidly. In this respect the cells of the kidney differ re- markably from the hepatic cells, the latter having a much thicker and firmer wall, which offers a greater resistance to the action of water. The cells have a distinct nucleus, and in the centre of this in many instances a nucleolus is clearly visible. (Fig- 164.) Fig. 1G4. a, b, c, d, epithelial cells from a healthy kidney. a contains no oil ; b, c, d, contain a few small oil globules in their interior, e, f, g, h, epithelial cells from a kidney affected with fatty degeneration ; the oil globules are much larger and more numerous than in the cells from the healthy kidney, m, por- tion of a urinary tube from a kidney affected with fatty degeneration. It, 7, fibrinous moulds of the urinary tubes from the urine of a patient with fatty degeneration of the kidney, each cylindrical mould entangles blood corpuscles, and a cell having a considerable number of oil globules in the interior. Medic. Chir. Trans, vol. xxix. Magnified 400 dia- meters. Another interesting feature in the renal se- creting cells consists in their containing in some cases minute particles of oil. In a perfectly healthy kidney, the quantity of oil contained in the epithelium is very small ; sometimes, indeed, it is difficult to find any cells which contain even the most minute particles of oil, while in other instances, where there is every reason to consider the organ quite healthy, the quantity of oil is much more considerable. When this material accumu- lates beyond a certain extent which it is diffi- cult to define, it must be considered ^as morbid, and a great excess of oil in the secreting cells constitutes a main feature of one of the most serious and intractable diseases to which the kidney is liable. The epithelium lining the straight tubes of the pyramids differs essentially from that of the convoluted tubes ; the latter, as before stated, is the true spheroidal or glandular variety of epithelium ; while the former approaches more nearly to the lamelliform or scaly variety. Its particles are smaller and more flattened, so that the epithelium in the medullary cones constitutes a much smaller proportion of the thickness of the tubes than does that in the convoluted tubes of the cortex. (Fig. 163. b .) The canal of the tubes in the medullary cones is also greater in proportion to the thickness of the wall than in the convoluted tubes. The cells in this portion of the tubes have uniform, smooth, and transparent walls, and their interior is less opaque and granular than is the case with the glandular cells before described. Another distinctive character con- sists in the fact of these cells seldom, if ever, containing oil. Ciliary motion in the tubes. — The preceding description of the epithelial lining of the uriniferous tubes corresponds in most par- ticulars with the usually received account of these structures. There now remain to be stated certain facts which probably are not generally known even to those who are ac- customed to make microscopical examinations of the kidney. In 1845, A. Kolliker published a short paper *, in which he mentions the interesting fact, that in the kidney of the em- bryo lizard the uriniferous tubes are lined by an epithelium remarkable for distinctly deve- loped ciliary processes, which may be seen in vigorous action for some time after the death of the animal. The ciliated epithelium, according to Kolliker’s observation, exists throughout the w'hole length of the tubes, except at the extremities next the common excretory duct. He also observed the cilia at the entrance of the Malpighian capsule. In a note appended to the same paper, the editor (J. Muller) states that he has observed the same phenomenon in the uriniferous tubes of a fish (Raia clavata). The cilia are very large and long ; they are directed along the axis of the tube, and have a wavy motion like that of a whip-lash. In the spring of the present year, before I was aware of the observations just now referred to, while examining the kidney of the newt (Triton and Lissotriton), I was surprised to find vibratile cilia in active mo- tion, not only within the Malpighian cap- sule as described by Mr. Bowman in the frog, but apparently extending throughout the whole length of the uriniferous tubes. I have since looked for this wonderful phenomenon in many of the animals just now mentioned, and have never failed to detect it in any one of the kidneys examined. The part of the kidney most favourable for the examination of this ciliary motion is the anterior extremity, where it is very thin and transparent, so that after being cut away with sharp scissors it requires no further preparation for micro- * Ueber Flimmerbewegungen in den Primordial- Nieren. Muller’s Archiv. 1845, and Edinburgh Med. and Surg. Journal, vol. lxviii. 254 REN. scopical examination. In a part thus pre- pared, I have sometimes seen the cilia in rapid action throughout the whole length of every tube in the field of the microscope, and a more wonderful or beautiful sight can scarcely be imagined. The motion commences within the Malpighian capsule; the little par- ticles floating in the liquid of the capsule are darted into the orifice of the tube with mar- vellous precision, and thence they are directed onwards through the windings of the tube in a current of liquid, which is propelled with great regularity and speed. Much violence in tearing up the specimen for examination ap- pears to arrest the motion ; and when water is added to the preparation, the epithelial particles swell and fill up the cavity of the tube, and so the motion is retarded. When the cilia are in slow motion, their form and the direction of their movement may easily be seen ; but when the motion has entirely ceased, I have never been able to see them distinctly, even with the best object glasses. The motionless cilia appear to collapse and fall upon the surface of the epithelium, and so become in- visible. Since my attention was first directed to the phenomenon in question, I have had but little time to search for it in other ani- mals ; but there appears reason to believe that it exists in most of the higher animals, and pro- bably even in man. The result of my own observations may be thus briefly stated : — In the newt I have searched for ciliary motion in the tubes many times, and have never failed to find it in any kidney which I have examined. I have searched for it in the frog twice (i. e. in two individuals), and found the ciliary motion very distinct in a considerable portion of one tube. I have examined one snake, and observed the motion very distinctly throughout a large extent of several of the tubes, as well as in the Malpighian capsules. I have searched for the phenomenon in the kidneys of some of the smaller Mammalia, as, for instance, in the mouse and the rabbit, but hitherto without success. I am not aware that any other observations with reference to this subject have been published, but possibly there may be some with which I am not acquainted. Epithelium of the pelvis and ureter. — The epithelium of the pelvis and ureter requires only a brief mention ; it belongs to the lamel- liform or scaly variety, and consists of flat- tened, delicate, transparent scales, having an angular outline caused by their lateral appo- sition, and a nucleus which is generally ec- centric. Function of the Malpighian bodies and urini- ferous tubes. — Before concluding this part of our subject, it appears desirable to make some allusion to the probable office of the several parts of the kidney, whose structure has passed under review. Mr. Bowman, in the paper to which reference has so often been made, has propounded a theory as to the office of the Malpighian bodies which I believe will soon be admitted as a true and well-established doctrine, based as it is upon accurate observation, and confirmed by sound reasoning and analogy. The theory in ques- tion, and the facts and arguments in support of it, are thus clearly stated by Mr. Bow- man : — “ Reflecting on this remarkable structure of the Malpighian bodies, and on their singular connection with the tubes, I was led to specu late on their use. It occurred to me that, as the tubes and their plexus of capillaries were probably, for reasons presently to be stated, the parts concerned in the secretion of that portion of the urine to which its characteristic properties are due (the urea, lithic acid, &c.J, the Malpighian bodies might be an apparatus destined to separate from the blood the watery portion. This view, on further consideration, appears so consonant with facts, and with analogy, that I shall in a few words state the reasons that have induced me to adopt it. I am not unaware how obscure are the regions of hypothesis in physiology, and shall be most ready to renounce my opinion, if it be shown to be inconsistent with truth. “ In extent of surface, internal structure, and the nature of its vascular network, the membrane of the uriniferous tubes corresponds with that forming the secreting surface of other glands. Hence it seems certain that this membrane is the part specially concerned in eliminating from the blood the peculiar prin- ciples found in the urine. To establish this analogy, and the conclusion deduced from it, a few words will suffice. I. The extent of surface obtained by the involutions of this membrane will by most be regarded as itself sufficient proof. But, 2. Its internal surface is conclusive. Since epithelium has been found by Purkinje and Henle in such enor- mous quantities on the secreting surface of all true glands, its use cannot be considered doubtful. It never forms less than ta-ths of the thickness of the secreting membrane, and in the liver it even seems to compose it en- tirely, for there 1 have searched in vain for a basement tissue, like that which supports the epithelium in other glands. The epithelium, thus chiefly forming the substance of secreting membrane, differs in its general characters from other forms of this structure. Its nu- cleated particles are more bulky, and appear from their refractive properties to contain more substance, their internal tissue being very finely mottled, when seen by transmitted light. In these particulars the epithelium of the kidney-tubes is eminently allied to the best-marked examples of glandular epithelium. 3. The capillary network surrounding the uriniferous tubes is the counterpart of that investing the tubes of the testis, allowance being made for the difference in the capacity of these canals in the two glands. It corre- sponds with that of all true glands in lying on the deep surface of the secreting membrane, and in its numerous vessels everywhere ana- stomosing freely with one another. “ These several points of identity may seem too obvious to be dwelt upon, but I have detailed them in order to show that in all HEN. 255 these respects the Malpighian bodies differ from the secreting parts of true glands. 1 . The Malpighian bodies comprise but a small part of the inner surface of the kidney, there being but one to each tortuous tube. 2. The epi- thelium immediately changes its characters,, as the tube expands to embrace the tuft ot vessels. From being opaque and minutely mottled, it becomes transparent, and assumes a definite outline ; from being bald, it becomes covered with cilia (at least in reptiles, and probably in all classes) ; and in many cases it appears to cease entirely a short way within the neck of the Malpighian capsule. 3. The blood-vessels, instead of being on the deep surface of the membrane, pass through it and form a tuft on its free surface. Instead of the free anastomoses elsewhere observed, neighbouring tufts never communicate, and even the branchlets of the same tuft remain quite isolated from one another. “ Thus the Malpighian bodies are as unlike, as the tubes passing from them are like, the membrane which, in other glands, secerns its several characteristic products from the blood. To these bodies, therefore, some other and distinct function is with the highest probabi- lity to be attributed. “ When the Malpighian bodies were con- sidered merely as convoluted vessels, without any connection with the uriniferous tubes, no other office could be assigned them than that of delaying the blood in its course to the capillaries of the tubes, and the object of this it was impossible to ascertain. Now, however, that it is proved that each one is situated at the remotest extremity of a tube, that the tufts of vessels are a dis- tinct system of capillaries inserted into the interior of the tube, surrounded by a capsule formed by its membrane, and closed every- where except at the orifice of the tube, it is evident that conjectures on their use may be framed with greater plausibility. “ The peculiar arrangement of the vessels in the Malpighian tufts is clearly designed to produce a retardation in the flow of the blood through them ; and the insertion of the tuft into the extremity of the tube, is a plain indi- cation that this delay is subservient in a direct manner to some part of the secretive process. “ It now becomes interesting to inquire, in what respect the secretion of the kidney dif- fers from that of all other glands, that so anomalous an apparatus should be appended to its secerning tubes. The difference seems obviously to lie in the quantity of aqueous particles contained in it ; for how peculiar soever to the kidney the proximate principles of the urine may be, they are not more so than those of other glands to the organs which furnish them. “ This abundance of water is apparently in- tended to serve chiefly as a menstruum for the proximate principles and salts which this secretion contains, and which, speaking gene- rally, are far less soluble than those ot any other animal product. This is so true, that it is common for healthy urine to deposit some part of its dissolved contents on cool- ing. “ If this view of the share taken by the water be correct, we must suppose that fluid to be separated either at any point of the secreting surface along with the proximate principles, as has hitherto been imagined, or else in such a situation that it may at once freely irrigate the whole extent of the secern- ing membrane. Analogy lends no counte- nance to the former supposition ; while to the latter, the singular position and all the details of the structure of the Malpighian bodies, give strong credibility. “ It would indeed be difficult to conceive a disposition of parts more calculated to favour the escape of water from the blood than that 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 Mr. 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, vide ante, p. 248-9. f 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 who had died jaundiced, and in whose urine there had been a large quantity of bile, I observed that 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 epithelial 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 medul- 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, ora 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. Disease of the lddney 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 * Meet. Chir. Trans, vol. xxx. lobules resulting from the binding down of the tissue by the interlobular septa, in the Fig. 165. Section of the kidney from a patient who had stricture. The pelvis and infundibula are much di- lated, the cortical portion is expanded, and its surface lobular. The parts are reduced about one third in the chawing. intervals of which the glandular structure is protruded by the distending force from within. The mucous membrane frequently 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 different 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 kidney from renal calculi. — 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 kidney 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 strumous 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 nephritis is not a common disease, but it is a very serious and a very 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. lie 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 (jig. 167). Both kidneys Fig. 167. Deposit in the urine of a patient labouring under 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 material, 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 kidney has been in a softened condition before the occurrence of the inflam- matory disease, as often happens 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 that the entire organ is of a dark slate colour. On a microscopical examination the con- voluted tubes are seen filled, in different de- grees, with nucleated cells, differing in no essential character from those which line the tubes of the healthy gland (Jig. 168). The Fig. 168. Section of a portion of inflamed lddney. 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 account 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 epithelial 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 divided by septa which correspond with the rings of fibrous tis- sue in the microscopic specimen. See Jig. 149, b. The cluster about b includes two 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 octahedral 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 desquamath e ( nephritis” to this form of disease.* Chronic desquamative nephritis 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. j- 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- I mixture of some abnormal product ; there is 1 * See tlie author’s paper on this subject in the ■ Bled. Chir. Trans, vol. xxx. 1 f This form of diseased kidney rvas first described H by Dr. Todd, under the name of gouty kidney, in a ■ clinical lecture which was delivered in June 1846, ■ and published in the Bledieal Gazette for June 1847. ■ In this lecture Dr. Todd alludes particularly to the ■ destruction of the secreting cells, and the consequent fl deficient excretion of the solid constituents of the jfl urine. B 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- milated products, which are being continually developed in gouty and intemperate subjects, and which are not normal constituents of the renal secretion. There would evidently be a certain limit 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 liquid 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 filling 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. Med. 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. (Jig. 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 epithelium remain (Jig. 171.) ; Fig. 171. Section of a portion of kidney, 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 Jigs. 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 (Jig. 172.), Fig. 172. a, Section of a portion of kidney showing the tubes lined by delicate transparent nucleated cells ; these cells have taken the place of the normal epi- thelium which has been destroyed and swept away ; b, 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 intervals of the matrix ; the constricted portions correspond with the surrounding rings of fibrous tissue. Mag- nified 200 diameters. Med. Chir. Trans, vol. xxx. 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 peculiar 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 inyfg. 173. The effect Fig. 173. Cylindrical moulds of the urinary 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 appear 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 kidney. 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. ( F/g. 174.) Fig. 174*. Section of a portion of kidney in which, serous cysts have been developed. At a there is a series of four cysts which are probably formed by the dilata- tion of a single tube. Compare this with f g. 172. From a specimen in the museum of King’s College. Natural 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 Mr. 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 Mr. 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. •261 11EN. 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, htemorrhage 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 {Jig. 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 strangury after taking oil of turpentine. Some blood corpuscles are entan- gled in the fibrine, as well as some octohedral crys- tals of oxalate of lime which the patient was ex- creting at the time the haemorrhage 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 Malpighian capillaries, and after filling the capsule has passed into the tube {fig. 176). This fact was first pointed out by Mr. Bowman. Fig. 176. Malpighian capsule and portions of the urinary tubes containing blood which has escaped from the Malpighian capillaries. Magnified 200 diameters. See also Jig. 119 d. The condition of kidney to which turpen- tine and cantharides give rise may result from s 3 262 REN. the irritation produced by certain products developed within the body. I have met with two well marked cases of 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 symptoms 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 haematuria 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 moulds, 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 haemorrhage 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 tubes, giving rise to the haemorrhagic spots before mentioned. It is only that form 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 fatty 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, all 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 below 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 epithelial cells are more or less distended with oil. (See figs. 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. Clair. Trans, vol. xxix. KEN. 263 a fatal termination. It is therefore as import- ant to distinguish 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. Baillief 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. J Can- * Med. Chir. Trans, vol. xxix. f The Morbid Anatomy of the Human Body. By Matthew Baillie, M.D. t 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. Raj'er 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 almost 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 occasionally, but rarely, witnessed in the kidney. 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 : — 1. 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 4 261 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. — Normal Anatomy and Phy- siology.— Bellini, Excercit. Anat. de Structura Renum, Florence, 1662, Leyden, 1711. Albiniis, 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. Berlin, Mdmoires de l’Acad. des Sciences de Paris, 1744. Ferrein, Memoires de l’Acad. des Sciences de Paris, 1749. Haller, Elementa Rhysiologi® Corporis Humani, Lausann®, 1757. Schumlansky, De Struc- tura Renum, Argentor, 1788. Eysenhardt, Diss. de Structura Renum Observ. Mic., Berlin, 1818. Meckel, Menschliche Anatomie, Plalle and Berlin, 1820. Ja- cobson, Isis, 1822, and Edinb. Med. and Surg. Jour- nal, 1823. Huschhe, Isis, 1828. Muller, De Glandu- larum Secernentium Structura, Leipzig, 1832. Lau- rent, De la Texture et du Developpement de 1’Appareil Urinaire. These de Concours, Paris, 1836. Berres. Anatomie der Mikroscopischen Gebilde, Vienne, 1837. Krause, a Muller's Archiv., 1837 ; h Hand- bueh der Anatomie, Hanover, 1848. Henle, Muller's Archiv., 1838. Cayla, Observ. d’ Anatomie Micros- cop. sur le Rein des Mammifferes. Thfese, Paris, 1839. Glage, Anatomiscli-MikroscopischeUntersuchungen, call. i. Minden, 1839. IVagner Physiologie, Leip. 1839 : Eng., by Dr. Willis, 1844. Gerber, Handbuch der Allgemeinen Anatomie, Bern. 1840. Vogel, Gebrauch des Mikroskops, Leipzig, 1841. Henle, Allgemeine Anatomie, Leipzig, 1841. Muller, Ver- gleichende Anatomie der Myxinoiden. Berlin. 1841. Bowman, Philosophical Transactions, part i. 1842. Goodsir, Monthly Journal of Medical Science, 1842. Reichert, Muller's Archiv., 1843. Gruby, Annales des Sciences Natur., vol. xvii. Muller, Handbuch der Physiologie, 4th ed. Coblence. Owen, Lectures on Comparative Anatomy, vol. i. 1843. Gerlach, Muller’s Archiv., 1845. Bidder, Muller’s Archiv., 1845. Kblliher, Muller’s Archiv., 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.— Blachall, Observations on the Nature 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, Reports of Medical Cases, 3 vols. 4to, 1827 — 1831, and papers in the Guy’s Hospital Reports. Rayer, Traite des Maladies des Reins. Trout, On Stomach and Renal Diseases. Christison, On Granular De- generation of the Kidneys, 1839, and in the Library of Practical Medicine. F. Simon, Handbuch der Medizinischen Chemie, translated by the Sydenham Society. Hecht, De Renibus in Morbo Brightii de- generatis, Berlin, 1839. Gluge, Anatomisch-Mikro- scop-Untersuchungen, Jena, 1841. Vogel, leones Histologic® Pathologic®. Henle, Henle und Pfeuf- fer’s Zeitschrift, 1842. Heller, Archiv. fur Physiol, und Pathol. Chemie und Mikrosk. band ii. Scherer, Chemische und Mikroskop. Untersuch., Heidelberg, 1843. Valentin, Repertorium, 1837 — 1838. Can- statt , De Morbo Brightii, Erlangen, 1844. Eichholtz, Muller’s Archiv., 1845. R. B. Todd, Clinical Lec- tures on Dropsy with Albuminous 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’sclie nierenkrankheit, Bremen, 1846. Peacock, Monthly Journal of Medical Science, 1846. G. Johnson, Med. Chir. Trans, vols. xxix. and xxx. Reports 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 body, 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 mamtnifera. 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, ci 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 only 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, * Cuvier, Regne 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 sensibility much greater than can exist betvveen one mammiferous animal and another, or one bird and another. Accordingly, 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- lonia), 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. — Testudinide;. Testudo (Land Tortoise), Emys (Fresh- water Tortoise), Chelonia (Turtle), Chelys, Trionyx. ORDER II. SALTRIA.* Family 1. — Crocodilid.e. Gavial, Crocodilus, Alligator. Family 2. — Lacertid.e. Monitor, Crocodilurus, Tupinambis, Ame- iva, Lacerta, Algyra, Tachydromus. Family 3. — Iguanidie. Stellio, Cordylus, Stellio, Doryphorus, Uro- mastix, Agama, Agama, Papayes , Tra- pelus, Leiolepis, Tropidolepis , Leposoma , Ca/otes, Lophyrus, Gotiocephalus, Lyrio- cephalus, Brachylophus, Physignathus, Is- tiurus, Draco, Sitana, Iguana, Ophryessa, Basiliscus, Polychrus, Ecphimotes, Opl Li- ras, Anolius. Family 4. — Geckotide:. Gecko, Platydactylus, Hemidactylus, Theca- dactylus , Ptyodactylus, Spheriodactylus , Stenodactylus, Gymnodactylus, Phyllurus. Family 5. — Chaiu/eleonid-E. Chamaeleo. Family 6. — SciNClDiE. Scincus, Seps, Bipes, Chalcides, Chirotes. ORDER III. OPHIDIA.f Family 1. — An guide. Anguis, Pseudopus, Ophisaurus, Anguis, Acontias. * a lizard, t ofn, a serpent. Family 2. — Serpen tide. Amphisbsena, Typhlops, Tortrix, Boa Scytalus, Eryx, Erpeton, Coluber, Py- thon, Cerberus, Xenopeltis , Heterodon, Hurria, Dipsas, Dendrophis, Dryinus, Dryophys, Oligodon, Acrochordus, Cro- talus, Trigonocephalus, Vipera, Naia, Elaps, Micrurus, Platurus, Trimeresurus , Oplocephalus, Acantliopkis, Echis, Lan- gaha , Bongarus, Hydras, Hydrophis, Pe- laniides, Chersydrus. Family 3. — Cecieiad.e. Caecilia. Osteology. — The Chelonian reptiles are distinguished from all other vertebrata by the peculiar 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 (Jig. 177, i) united to each other towards the mesial line by a longitudinal series of angular plates, which are in fact the spinous processes (neural spines ) of as many vertebras 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 vertebras which do not enter into its compo- sition (Jig. 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 vertebra, 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 maybe 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 of Tortoise. A, superior maxilla ; b, inferior maxilla ; c, ossiculum audit us ; d, os hyoides ; e, cervical vertebrae ; f, dorsal vertebrae ; o, sacrum ; h, caudal vertebrae ; I, dorsal ribs ; li, marginal scales ; N, scapula ; o, coracoid bone; P, os humeri; Q, radius; R, ulna; s, bones of the carpus; T, metacarpal bones; u, digital phalanges ; v, pelvis ; w, femur ; x, tibia ; y, fibula ; z, tarsus ; as, 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 (fig. 177, p) form a sort of osseous frame composed of a series of bones, eleven in number on each side, which are united together by 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 synchondrosis. 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 rep- 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 Geoffroy St. Hilaire in ac- cordance with the situations that they occupy. The anterior pair are the episternal pieces, and the pair situated behind these the hyo-slernah. In the centre bounded by the above four bones is the azygos piece named the ento- sternal. The pair situated immediately pos- terior to the hyostcrnal are called the hypo- sternal pieces, and the two which terminate the plastrum xipho-sternals. The sacral and caudal vertebrae return to the usual arrange- ment, being all free and moveable, having their bodies concave in front and convex be- hind, and their apophyses as in ordinary ver- tebrae. 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 (fig. 178.), which is suspended on each side by a ligamentous attachment beneath the second vertebra of the carapax. The branch which is thus suspended ( «), 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, scapula ; b, acromion process ; c, coracoid bone. tiles, nothing like it existing in any other ver- tebrate animals : nevertheless, the relations oi 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. the ilium (fig. 179, a.), which is Fig. 179. Pelvis of the Turtle, a, os ilii ; 6, 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 plastrum, 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 (fig. 180, c, 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 dismem- 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. 181.), itisneces- Fis. 181. have three like the middle ones. The thumb or great toe has but two ; it is furnished with Fig. 182. 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 , df), which are nearly of a square shape, of five bones of the second row (1, 2, 3, 4, 5,) sup- porting the metacarpal bones, and of an inter- mediate bone ( e ), situated between the great radial {a'), the first cubital, and those which support the third and fourth metacarpal bones. This intermediate bone is very frequently con- solidated with the great scaphoido-semilunar bone, as represented in the figure. The bones of the metacarpus in these tortoises are even shorter than the phalanges. Hind Feet. — In the Chelonians, the os calcis does not project posteriorly, so that the tarsus is as flat as the carpus. In the turtles {Jig. 182.), it is composed of six or seven bones, according as the last is reckoned as belonging to the tarsus or to the little toe. Two constitute the first row, of which the larger (a'), which is nearly of a rhomboidal shape, and connected both to the tibia and fibula, is the astragalus ; the smaller ( b ), con- nected to the fibula alone, is the only repre- sentative of the os calcis. In the second row there are four pieces, three of which are cuneiform bones, support- ing the metacarpal bones of the great toe, and of the two following ones ; and the fourth, which is of larger size, appropriated to the two last metatarsals. The metatarsal bones of the great toe and of the little toe are singularly broad and flat ; indeed, that of the little toe (c) might be taken for one of the tarsal bones a little removed from its place, in which last case the little toe would consist of only two phalanges : according to the former supposition it would Hind-foot of Trionyx. a nail at its extremity, as well as the finger which is next it ; the two following have their terminal phalanges large but without nails ; the last phalanx of the little toe is very small. In the land-tortoises the analogue of the Fig. 183. Hind-leg of Tortoise. astragalus is more bulky and thicker, whilst the fibular bone or analogue of the os calcis is proportionally smaller. The other four tarsal bones are present, and in this case that which supports the little finger seems to form one of the series, both from its position and its shape ; sometimes it supports a rudiment of a little toe consisting of one piece only, but in many species this is wanting. The metatarsal bone of the great toe is short but not flattened ; the others are a little longer : none of the four toes have more than two phalanges. In the Chelonian reptiles, the os hyoides varies very remarkably as to its form in REPTILIA. 269 different genera, and even in different species. It generally consists of a body or centrum, which is sometimes itself divided into several pieces, and of two and sometimes three pairs of cornua ; also under the anterior part of its body there is suspended a bone or a cartilage (sometimes double) which is the special bone of the tongue, the analogue of the lingual bone of birds, only in them it is articu- lated in front of the body of the hyoid bone, whilst in the Chelonians it is suspended under- neath. The greater cornua (the anterior pair, when only two pairs are present, the middle pair when there are three, that which represents the styloid bones) embrace the oesophagus, and mount up behind those muscles which represent the digastric or depressors of the lower jaw, but without being attached other- wise than by their own muscles. In Trionyx, the body of the os hyoides, is composed anteriorly of a cartilaginous point, beneath which is suspended a large lingual cartilage of an oval form. At the base of each pointed cartilage there is attached an osseous piece of a rhomboidal shape, which represents the anterior cornua; behind this are four other pieces, forming a disc, which is concave superiorly, broadest in front, and deeply notched both posteriorly and on each side. To the anterior angles of this disc are appended the middle cornua and to the pos- terior the posterior cornua. All four of these cornua are considerably ossified. The middle cornua consist of one long piece, which is compressed, of an arched form, and termi- nated by a little cartilage. The other cornua are broader and flatter ; they are eked out by a cartilage, in the thickness of which are enclosed five or six osseous nuclei, all placed in a line with each other, each of a round or oval form, and quite hard and distinct, so that the os hyoides of this reptile seems to consist of twenty different osseous pieces, which apparently remain distinct through life. The hyoid apparatus of Chelys is equally remarkable. Its body is composed of a single long narrow piece, of a prismatic shape, hol- lowed above into a canal in which the trachea is lodged. Anteriorly, this central portion ex- pands in order to sustain two additional pieces on each side, four in all, without reckoning the centrum itself. The two middle ones unite in front, leaving a space between them- selves and the principal body, which is closed by a membrane upon which the larynx reposes. The two lateral pieces perhaps represent the anterior cornua ; it is at the dilatation that they form with the expanded portion of the centrum that the middle cornua are ar- ticulated : these are very strong and prismatic for the internal half of their course ; afterwards slender ; and they give attachment externally to an additional piece, which is distinct from the rest of the cornua. The posterior cornua are articulated to the posterior extremity of the prismatic portion of the centrum; they are long, slightly com- pressed, and curved. Under the anterior and dilated portion is suspended the lingual bone, which consists anteriorly of a semicircular cartilage, and behind of two crescent-shaped osseous pieces, the inner angle of which is prolonged into a kind of tail or pedicle that passes beneath the prismatic body of the hyoid bone. In the turtles, the body of the hyoid re- sembles an oblong shield, concave upon its upper surface for the sake of lodging the larynx and the commencement of the trachea ; pointed in front, where it forms part of the tongue, laying above the lingual bone. The anterior cornua are very small ; the great cornua are articulated to 'the middle of its lateral margin, and have at their free termi- nations additional cartilaginous pieces. The posterior cornua are attached to the posterior angles. The pelvis of lizards {fig. 184.) is composed Fig. 184. Pelvis of Crocodile, a, ileum ; b, ischium ; c, pubis. of three bones, which, as in quadrupeds, assist in the construction of the colyloid cavity. The os ilii (a) occupies the upper half ; its neck is broad and short, and its spinous portion, instead of running forwards, as in mammifers, or being rounded, as in the crocodile, is di- rected obliquely backwards, in the shape of a narrow band. Inferiorly, the pubis ( b ) and the ischium ( c ) are conjoined with their fellows of the opposite side along the mesial line ; but the pubis does not unite with the ischium, and consequently the two infra-pubic foramina are only separated from each other by a liga- ment. The pelvis of the different genera of lizards are principally distinguished from each other by the symphysis of the pubic bones, which in the monitors is formed by the junction of two broad truncated surfaces ; but in most other genera by a much less extensive union. The junction between the ossa ischii is always effected by a wide surface. The chameleon differs from all other lizards in having the ossa ilii straight, and directed almost perpendicularly upwards, to be at- tached to the spine. They are likewise re- 270 REPTILIA. markable, because they terminate in a tri- angular cartilage, analogous to that which ekes out the scapula. Vestiges of the pelvis may be traced in Opkisaurus and Angitis, under the shape of a little os ilii, with a vestige of the ischium, but without any symphysis. The cylindrical bones of the anterior and posterior extremities present nothing worthy of special remark. The carpus (fig. 185.) consists of nine bones, the disposition of which is not unlike that of the carpal bones of a monkey. In the first row there is a radial bone (e), a cubital (d). Fig. 185. a, the ulna ; b, the radius ; c, radial car- pal bone ; d, ulnar carpal bone ; e, os pisiforme ; f a len- ticular bone inter- posed between the ulnar carpal bone and the metacarpal bones of the three inner fingers. Hind-leg of Crocodile. a, the tibia ; b, the fibula ; c, the astragalus ; d, the os calcis ; e, the os cuboides ; f, the cuneiforme, there is a flattened triangular su- pernumerary bone attached to the outer side of the cuboid, which in the figure has no letter of reference. Fig. 187. Tarsus of Lizard. a, the tibia ; b, the fibula ; a', the astragalus ; b', the os calcis ; c, the os cuboides ; d, the cuneiforme. which is of large size, and an os pisiforme ( e ) attached to the inferior extremity of the ulna. In the second row there are five small bones arranged in a curvilinear form, and corresponding with the five metatarsal bones : the ninth (f) is interposed between the two large bones of the first row, and the first, second, third, and fourth of the second, form- ing a kind of central piece to the carpus. The tarsus of lizards, like that of the croco- dile, is composed of four bones only. The first row consists of two : one tibial (fig. 187, a'), which is likewise slightly articulated with the fibula ; the other fibular (b), of smaller dimensions, which, however, soon unites into a single piece with the former, situated on the same plane. The second row likewise consists of two REPTILIA. 271 bones, the larger of which ( air - - - J Barometer, in English) inches - - - j Average of the lower temperature, 47°'24 F. Average of the higher temperature, 66°-92 F. Difference between the higher and lower temp. 72-93 71-29 1-64 12-16 11-57 0-59 33-44 31-76 1-68 406-99 366-97 40-02 18-25 15-72 2-53 4-48 4-28 0-20 29-719 29-647 The experiments of Letellier$ on warm- blooded animals agree in their results with * Memoires de l’Acaddmie Eoyale for 1789. •j- Experiments and Observations on Animal Heat, p. 311 — 315. 2nd edit. 1788. % Wagner’s Handworterbucb, band ii. S. 878, 879, und 880. Physiologie des Athmens, S. 73 — 82. § Comptes Rendus, tom. xx. p. 795. 1845. An- nales de Chimie et de Phys. tom. xiii. p. 478. 1845. Letellier has thrown the results of his experiments into the following table. He does not state whether he measured the temperature by Reaumur, or the RESPIRATION. 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 1*8 1 1 English inches), the quantity of oxygen gas consumed was dimi- nished.-)- 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 33G"' (29-841 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 0'74 „ 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. Surrounding Temperature. From 159to 20° From 30°to 40° At the freezing point. For a Canary For a Pigeon For two Mice For a Guinea Pig 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 l’lnfluence des Agens Physiques sur la Vie, ' chapitre vi. t Annales de Chimie et de Physique, tom. iv. p. 113. 1817. + Thomson’s Annals of Philosophy, vol. iv. p. 335. 349 proportion of 4-450 to 4-141, the difference between the absolute quantity of that gas in the expired air at the 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 Gavarret-f-, 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 experi- ments of the apparatus suggested by Dumas and Boussingault. Part of this apparatus 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 experiments 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 mine, 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. viii. p. 129. 1843. J Annalen der Chemie und Pharmacie, 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. Scharling 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, cateris 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 of!' 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 point 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*77 1 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 1 29*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 1 1 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 children Woman 264 94 19 Weight of body in Troy lbs. 154*73 219*70 175*49 183*30 58*96 C1-G4 60*30 149*41 Quantity of carbonj exhaled in grains. In 24 hours. 3453*90 3699*50 3386*77 3513*39 146*39 In 1 hoar. 143*91 154*14 141*11 2054*53 1929*89 1992*21 2540*88 85*6u 80*41 83*10 105*87 f 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 Influence of the respiratory movements upon the evolution of carbonic add from the lungs. — This point has been particularly ex- amined by Vierordt in 17 1 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 absolute 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 view. 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. f 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 asgroto 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 this case. f Wohler and Liebig’s Annalen der Chemie und Pharmacie, band lvii. S. 1. 1846. The male adult and the boy were naked during the experiment. + Physiologie des Athmens, vierter absehnitt, S. 102—149. 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 : — 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 l-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. wrhen 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 0-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 1. Male aged 28 years 2. — — 16 — 3. Boy — 9f — 4. Young Woman 19 — 5. Girl - - 10 — Total quantity of carbon from thewholebody 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 f 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 500 cubic centimetres (30'5 English cubic inches), and the percentage of carbonic acid to be 4-l. N umber of respi- rations in a minute. Percentage of carbonic acid in the expired air. Volume of the ex- pired air in a minute. Volume of carbo- nic acid gas in the expired air in a minute. Volume of carbo- nic acid gas in each ex- piration. Measured in English cubic inches at a temperature of 98°-6 F., and under a baro- metric pressure of 29-841 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 1464-000 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. Yierordt, 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 l-73 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 12 382 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 100 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 T55 pir 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 •)- 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 * Philos. Transact, of London for 1808. f Opus cit. RESPIRATION. 353 cent. ; while, if they were allowed to remain in it until they had become asphyxiated, it con- tained ]2'75 per cent. Vierordt, in three experiments, breathed, from 1 a to 3 minutes, a volume of air amounting to 427 English cubic inches, and found, on an average, the carbonic acid gas l-5 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 expelled 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 body, 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 Scharling * * * * §, the loss of carbon by the lungs and skin is 3543' 13 Troy grains, or 7'382 oz. Troy, f Liebig J 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 lungs in the twenty -four hours by other experimenters, differ con- siderably.. Lavoisier and Seguin estimated the loss of carbonic acid gas at 14,930 cubic inches, which they believed would yield 2776*304 grains Troy; ! Messrs. Allen and Pepys at 39,534 cubic inches of carbonic acid gas, containing rather more than 11 1 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 proceeded 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 gas by the lungs and skin. From the data thus obtained he calculates that an adult male, taking moderate exercise, loses 13'9 oz. of carbon daily by the lungs and skin ; and that 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 experiments upon the in- mates of the Bridewell at Marienschloss (a prison where labour is enforced), he calculates that each individual lost in this manner 105 oz. of carbon daily ; while in another prison, where the inmates were deprived of exercise, this loss amounted only to 8'5 oz. daily7. * 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 inference^ 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 invertebrata, 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 was 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 difficiilt must it be to ascertain the average quantity during the twenty- four hours. | Animal Chemistry, &c., edited by Dr. Gregory, p. 13 ; 3rd edit. 1846. * Opus cit. p. 46. j- Annalen der Chemie und Pharmacie, von Woh- ler und Liebig, Band lvii. S. 1. 1846. 1 Opus cit. p. 9. § The results of the various experiments upon A A 35i 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 this 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 advanced 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 was 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 evolution of carbon, combined with those of Quetelet upon the average weight of the body at this period of life. * * 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 (Marchand) P342= 4 Man (Scharling) 4'506= 12 Pigeon (Boussingault) 42-317= 1 14 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 was published, are thrown into a tabular form in Burdach’s Physiologie, 2nd edition, trans- lated by Jourdan, tom. ix. p. 512. * A table constructed on these data, exhibiting the probable quantity of carbon which combines with oxygen to form the carbonic acid gas evolved at the lungs at different ages in the human 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 volume 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 oxygen 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 : 1T742, they maintain that for every 1 volume of carbonic acid gas evolved from the blood, 1‘1 742 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 life 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- cording to the law of the diffusion of gases. Vi e shall have occasion to make some remarks on this subject when we come to discuss the theory of respi- ration. f Opus cit. p. 571. The weights and measures in the original table are here reduced to Troy weight and English cubic inches. RESPIRATION. 355 Years of age. Average weight of body in Troy pounds. Carbon consumed, in Troy grains. Quantity of oxygen which disappears from the inspired air. In grains. . Overplus of oxygen above what is neces- sary to form the car- bonic acid gas. In Troy grains. Volume of oxygen that disappears from the inspired air un- der a pressure of 29-92 inches, and a tempe- rature of 82° E. In English cubic inches. Ini hour. In 24 hours. In lhour. In 24 hours. 1 In lhour. In24hours. 1 In lhour. In24hours. 8 59-62 77-165 1864-306 240-955 5782-806 35-233 845-604 526-907 12645-770 15 124-34 134-267 3222-410 419-252 10062-069 61-207 1468-974 1154-142 27699-422 16 143-05 C164-13) 166-676 4000-233 520-447 12490-852 75-976 1823-439 1432-669 34384-076 18—20 W f 174-15 ) 175-936 4222-468 549-399 13184-782 80-359 1928-631 1512-432 36298-371 20—24 ‘° (184 36 ) C 184-36) 188-282 4518-782 587-904 14110-083 85-622 2054-934 1618-436 38842-098 40—60 1 t0 f 1 175-49 J T175-49) 155-873 3740-959 486-710 11681-052 71-099 1706-395 1339-847 32156-346 60—80 4 t° l (164-02 ) 141-983 3407-606 443-34 10640-250 64-926 1558-239 1220-478 29291-495f From the details given above we may ob- tain information of considerable importancn on several practical points. A eonsideratioe 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 already 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, troisifeme serie, 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 10i 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 1 2 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 j-, 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.^ * Edinburgh Medical and Surgical Journal, vol. lxv. 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- tween the cold-blooded and warm-blooded animals. Yauquelin (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 Phenomfenes Physiques des Corps Vi- vants, p. 115. 1847), obtained similar results on a torpedo confined in a limited quantity of water. J Dr. Snow infers from his experiments on the lower animals that in the human species “ five or A A 2 356 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 likely 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 pure carbonic acid gas to the atmospheric air to produce the same effect. The great activity 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 245). Legallois (Annales de Chimie et de Physique, tom. iv. p. 113. 1817) had previously 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 which division of the vagi nerves causes death. (Edinburgh Medical and Surgical Journal, vol. li. p. 298 to 302. 1839.) t We have published a series of experiments (Edinburgh Medical and Surgical Journal, vol. lv. 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 Bichatjupon the effects of the venous blood in suspending the sen- sorial functions. In an excellent experimental essay on this subject, published subsequently to our essay (Edinburgh Med. and Surg. Journal, vol. lxiii. 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 found that, when the suspension of the respiration had been Experiments have been made by Njsten*, by Mr. Macgregorf, Dr. Malcolm^, 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 somewhat 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- oarried so far as to arrest the flow of blood through the lungs, the admission of atmospheric air was in- 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 with that kind only of con- tractility which manifests itself by slow contractions and equally slow relaxations. * Recherches de Physiologie et de Chimie Patho- logique. Seeonde section. 1811. t Edinburgh Monthly Journal of Medical Science, vol. iii. p. 1. 1843. J Transactions of British Scientific Association, for 1840, p. 87. § De Quantitate relativa et absoluta Acidi Car- bonici ab Ilomine sano et asgroto 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 different vertebrata, and is greater in birds and in the mammalia than in reptiles and fishes ; and it also varies in different con- ditions of the body and surrounding media in the same animal. In animals exposed to artificial high temperatures* * * §, or living in warm climates -j-, 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 from 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 approaches 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 J, and lo-01 C (1°"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 1053.1 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. f Dr. J. Davy. London Phil. Transact, for 1838, p. 28. t 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 temperature varied from 1° to 3° F. § Annales des Sciences Naturelles, 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 j distant from the heart. || Researches, Physiological and Anatomical, vol. i. p. 146. Opus cit. vol. ii. p. 22. count, — where the quantity of water was greater in the arterial than in the venous blood decidedly preponderates. In all pro- bability the relative quantity of water in the two kinds 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 blood in different genera of animals, and even in different individuals of the same species.* In the greater number 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 Letellier and Simon tend to show that the proportion is fluctu- ating. According to Simon, the blood-cor- puscles of arterial contain less hsematin 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 differences between the two kinds of * Nasse (article Blut, in Wagner’s Handworter- buch der Physiologie, Band i. S. 171) states that the difficulty of conducting a correct quantitative analysis of the fibrine of the blood is sufficient to ac- count for these discrepancies. f 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 Handwijrter- buch already referred to, and the first volume of Simon’s Animal Chemistry, translated for the Sy- denham Society, by Dr. Day. J The Chemistry of Vegetable and Animal Phy- siology. Translated from the Dutch by Fromberg, Part II. p. 334. A A 3 358 RESPIRATION. blood, mentioned above. Michaelis * * * §, and Marcet and Macairef, in their 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 1tl cubic inch of carbonic acid gas, and 4L. of a cubic inch of oxygen || ; and that he procured carbonic acid gas from human venous blood heated to 112 Fahr.lf 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 singula- rium Partium Sanguinis arteriosi et venosi. Berolini, 1827. t Annales de Chimie et Physique, tom. li. p. 382. 1832. J Lelirbuch der Chemie, Band iv. S. 99, 100. Dresden, 1831. § Zeitschrift fur Physiologie, Band v. 1833. Mit- scherlich, Gmelin and Tiedemann, by the addi- tion of acetic acid, and the application 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. || Beddoes’ Contributions to Physical and Medical Knowledge, p. 132. 1799. 8f 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- lat’d de Martigny $ and Enschut j| 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.f, Stevens**, Dr. G. Hoffman f-]-, Enschut 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. Davy HIT , Mitscherlich, Gmelin, * Dissertatio Physiologico-Medica de Respira- tionis Chymismo, 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 car- bonic acid gas from venous blood, and 1 to 2’5 cubic centimetres (’061025 to T5256 English cubic inches) of the same gas from arterial blood, p. 99. Enschut points out various precautions necessary to be ob- served to secure accuracy in such experiments, a want of attention to which, he believes, was the cause of the failure of Dr. J. Davy, Muller, and others, in their attempts to obtain carbonic acid gas from blood by heat, p. 100 — 104. f 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 observed the escape of free carbonic acid gas from the blood during its coagulation, — an observation not confirmed by others. It appears that Vogel also obtained carbo- nic acid from venous blood by means of the air- pump. (Schweigger’s Journal, Band xi. S. 401, as quoted by Bischoff.) J 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 ounces of blood. § Magendie’s Journal de Physiologie, tom. x. p. 127. 1830. || Opus cit. p. 115. ®[f Meckel’s Archiv, Band ii. 1816. Nasse al- lowed the hydrogen to stand over blood from 24 io 48 hours. ** Philos. Transact, vol. xlvi. p. 345. 1835. ff Medical Gazette, for 1832 — 1833, vol. xi. p. 881. Diss. de Respirationis Chymismo, p. 124tol26. Enschut obtained carbonic acid by this means also from arterial blood, but in smaller quantities than from venous blood. §§ Experimental Essay on the Physiology of the Blood, p. 52. Edinburgh, 1837. 1111 Commentatio de Novis 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. 506. 1823. RESPIRATION. 3.59 and Tiedemann * * * §, Stromeyer f , Mliller 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 -Jg-th, and sometimes to ith of the volume of the blood erupted ; 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 ith 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-ith, and often -ith, 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 j per cent, of the volume 10 3'3J of blood employed.*! 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. f Dissertatio Liberamne Acidum Sanguine con- tinetur. Gottingen, 1831. j 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 (Preface to BischotFs Commentatio de Novis quibusdam Experimentis, &c.) also in small quantity from venous blood. § PoggendorfFs Annalen der Physik und Chernie, Band xl. S. 583. 1837. || Idem opus. Tf Poggendorffs Annalen, Band lxvi. S. 202. 1845. Enschut had, previous to Magnus’s experiments, obtained azote from both kinds of blood, and in greater quantity from venous than from arterial blood. Opus cit. p. 159. of their constituent parts, the following results are obtained : — Carbonic acid gas Oxygen - Nitrogen* Arterial blood. Venous blood. Cubic centimetres. 39-5 or 62-3 per cent. 14-7 — 23-2 — 9-2 — 14-5 — Cubic centimetres. 47-5 or 7L6 per- cent. 10-1 — 15-3 — 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 12 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 to the temperature of 32 Fahr. and the mean barometric pressure, from l "7 to 3-3 per cent, of the volume of the blood emploj'ed. 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 * PoggendorfFs Annalen, Band lxvi. S. 189. Gay Lussac (Annales de Chimie et de Physique, 3me serie, tom. x. p. 1. 1844), has brought forward va- rious objections against the inferences drawn 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. Mag- nus has replied, and on the whole successfully, to these objections of Gay Lussac (Opus cit. Band lxvi). 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 different 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 from each of the two kinds of blood. f Poggendorff ’s Annalen, Band lxvi. S. 202. In some experiments the quantity of nitrogen absorbed by the blood, when previously agitated with carbonic acid, was 6-5 per cent. Though these various results obtained by Magnus in his experiments have not been fully confirmed by others, indeed several expe- rimenters, such as Enschut, Bischoff, and Dr. J. Davy, who succeeded in procuring carbonic acid gas both from venous and arterial blood, failed in ob- taining decided evidence of the presence of oxygen gas, yet they appear to have been so carefully and repeatedly performed, that a belief in their general A A 4 3G0 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’OTroy grains) of blood, was 0T32 gram. ( l-937 grains) of free, and 0’6759 gram. (KT431 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 2T9G8 cubic inches of combined carbonic acid.'f 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 (Journal fur 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 qualitative 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 by 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 fur 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 off 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 carbonic 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 lvii. S. 126. 1846), but without sufficient reason, as Marchand (Journal fiir praktische Chemie, Band xxxvii. S. 321. 1846), Lehmann (idem opus, Band xl.), and Moleschott (Hollandische Beitrage, Band i. hedft ii. S. 163. 1847) have shown.' * Dr. J. Davy (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 praktische Chemie, von Erdmann und Marchand, Band xl. S. 133. 1847. of Spallanzani* and Dr. W. F. Edwardsf 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 §, Collard de Mar- tigny || , Muller and Bergemannf , Bischoff** and Marchand f j, on frogs confined in hy- drogen or azote ; and those of Dr. W. F. Edwards JJ, 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 f T, 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 j-f-f, 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 Differences in the form of the red corpuscles in venous and arterial blood. — The physical * Memoires sur la Respiration, p. 346 to 351. f De P Influence des Agens Physique sur la Tie, p. 449. 1824. J Opus cit. p. 447, 448. § Opus cit. p. 442 to 447. j! Magendie’s Journal de Physiologie, tom. x. p. 122 to 124. If Muller’s Elements of Physiology, translated by Baly, vol. i. p. 354. ** Commentatio de Novis quibusdam Experi- mentis Chemico-Physiologicis, p. 20. ft Journal fur 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. ft Opus cit. p. 453 to 455. Recherches de Physiologie et de Chimie Patho logiques, p. 225 to 229. 1111 Researches, Chemical and Philosophical. Divi- sion II. Coutanceau’s Revision des Nouvelles Doctrines Chimico-Physiologiques, p. 280 to 302. 1821. Cou- tanceau and Nysten 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. Iff Recherches, &c. p. 230, 231. j J j 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. 361 conditions of the 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 exosmotic 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 *, Schultz f, IT. NasseJ, Scherer $, Reuter ||, Mr. Gulliver^, 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 -) — j- ; while BurdachJJ, Muller Bruch || || , and Marchand Iff, have failed in de- tecting by the microscope any difference 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 * Experiments circa Statum Sanguinis et Yaso- rum in Inflammatione, p. 71. 1826. t Das System del- Circulation, S. 27. 1836. % Handworterbuch der Physiologie, von Wagner, Bandi. S. 97. 1842. § Zeitschrift Fur Bationelle Medizin. Herausge- geben von Henle und Pfeufer, Band i. heft ii. S. 288. 1843. || Idem opus, Band iii. heft ii. S. 165. 1845. 1. Work of Hewson, printed for the Sydenham Society, note at p. 9. 1846. * *_ Monographie iiber den Einfluss der Gase auf die Form der Blutkorperchen, von Bana temporaria. Erlangen, 1846. ff We 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 two 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. t+ Traitd de Physiologie, &c. traduit par Jourdan, tom. vi. p. 135, 136. 1837. §§ Elements of Physiology, translated by Balv, vol. i. p. 346. 1840. 1111 Zeitschrift, &c. Yon Henle und Pfeufer, Band i- heft iii. S. 440. 1844 ; Band v. heft iii. S. 440. 1847. ITU Journal fur praktische Chemie, Band xxxviii. IS. 279. 1846. 1 *** Dr. G. 0. Rees (Med. Gazette, Session 1844-5, p. 840) maintains that the structure of the red par- icles prevents the possibility of their assuming any 'ther form than the biconcave in a fluid of the 'pecific gravity of serum, whether exposed to air or '°t > hut this statement appears to be founded upon he presumed effects of the endosmotic and exosmo- i'c conditions of the red corpuscles, and not upon any .xamination by the microscope of the effects of gases pon 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 mammalia, 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 respiration. — The actions be- tween the blood and the atmospheric air in the performance of the function of respiration 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 between 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 disappears from the inspired air ; 3dly, the nature of the changes the blood undergoes in passing from the venous to the arterial condition. 3G2 RESPIRATION. On the manner in which the air in the upper and lower parts of the respiratory apparatus becomes intermixed. — The respiratory qualities of the other parts of the inner surface of the air-passages must he 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 expired 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 oxygen 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 atmospheric air in the lungs, by which 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.-)- * Edinburgh Transactions of Royal Society, vol. xii. p. 573. 1834. t Seguin and Lavoisier “ Sur la Transpiration des Animaux,” in Memoires de l’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, who appear to re- gard the function of respiration simply as a process of combustion, but who do not uphold the opinion that this combustion takes place in the lungs and that the watery vapour in the expired air is imme- diately derived from this source, that a part of the oxygen that disappears from the inspired air unites with hydrogen to form water. No satisfactoiy 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 (Aunales de Chimie, tom. ix. p. 261. 1791), which has received various modifications since his time, was based on the view that the purple colour of the venous blood is the result of the combination of oxygen with 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 with 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 experiments 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. Philos. 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 fur 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 inversely 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, oxygen 0-9487, and carbonic acid 0-8091. (Trans- actions of Royal Society . of Edinburgh, vol. xii. p. 222. 1834.) In some later experiments Mr. Gra- 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 diminished, 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 rapidly, 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 Medical Sciences, Nov. 1830), and by other experimenters, is not in accordance with the law of the diffusion of gases, as determined from experi- ments upon their diffusive velocities through porous septa into the atmospheric air-, and through minute apertures in a thin plate into a vacuum. When a bladder filled with 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 which the diffusion of the gases occurs, are not the same as those in respiration ; and we find the carbonic acid gas passing in greater quantity through the organic membranes than the oxygen,— 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 interchange 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- sorbed, 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 will 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 evolved 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 being 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 blood, 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 physiologists, the more especially as the attempts to detect free oxygen in the arterial blood had failed in all 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 in 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- lin, Tiedemann, and Mitscherlich (Zeitsehrift fur Physiologic, 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 se'- 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, 3me edit.) 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 tins latter salt, by a real combustion, is converted into carbonate of soda, which is decomposed in its turn in the lungs by a fresh portion of lactic acid. Liebig (Organic Chemistry of Physiology and Pathology, edited by Gregory, p. 2G5. 1841) supposes that car- bonate of protoxide of iron exists in the red cor- puscles of venous blood, and that in its passage through the lungs, a large portion of the absorbed oxygen unites with it, forms hydrated peroxide of iron, and sets the carbonic acid free. Mulder (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 peroxide of iron in respiration is impos- sible, and maintains that the absorbed oxygen com- bines with the proteine compounds of the blood and forms oxy-proteine, which being conveyed by the RESPIRATION. 3G5 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 Mart-hand 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 carbonic 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 phosphorus, 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 hfematosine. See Dr. Rees’ paper in the Lond. Edin. and Dubl. Phil. Mag. for July, 1848. — Ed.] * Marchand (Journal fur praktische Chemie, Band xxxv. S. 385. 1845) in his experiments found 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 invalidate 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 haematosine or colouring matter of the blood is enclosed within the enveloping membrane of the red corpuscles ; that this hgematosine, 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 oxygen 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 hasmato- 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 f, 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 andforms or liberates carbonic acid gas, drawn from the experiments of Scherer (Annalen der Che- mie und Pharmacie, Band xl. 1841) upon the action of oxygen gas upon fibrin, and those of Berzelius (Lehrbuch der Chemie, Band iv. S. 94. 1831), and Maack (De Ratione quaj Colorem Sanguinis inter, &c., p. 35. Elite 1884) 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. f Dr. J. Davy and others. 3GG RESPIRATION. with hydrogen gas * * * § and the addition of a saline solution, of the same strength as that existing in the blood f, 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 J, 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 || ; while others believe that the action of tile oxygen on the blood is analogous to that of the nitrous oxide on the solutions of * Bischoff, Dr. Maitland, Nasse, and Marchand. t Gregory and Irving (vide London Medical Ga- zette, vol. xiii. p. 814. 1834). Nasse (Wagner’s Handworterbuch,&c., Band i. S. 182) affirms that even concentrated solutions of muriate 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 itwith the aid of the salts. t Nasse (opus eit. 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. || Scherer, Reuter, and Gulliver. Mulder (The Chemistry of Annual 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, hut he gives a very different explanation of the cause of the change in the form of the red particles from the other support- ers of this view. According to Mulder, part of the oxygen absorbed unites with some of the proteine compounds in the blood in the lungs, and forms oxy- proteine, and this finnishes a thin envelope to the red corpuscles, 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 praktisehe Chemie, Band xxxviii. § 276, 277) and Dumas (Comptes Rendus for 1846, tom. 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 evidence 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. 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Dumas concludes, that neither the presence, of albumen nor fibrin is necessary 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 with insuperable diffi- culties (opus cit. Band xxxviii. S. 278). * Magnus and Marchand. RESPIRATION. 367 ]a Respiration produit dans l’Air, in Memoires de la Societd d’Arcueil, tom. ii. 1809. Provengal and Humboldt, Recherches sur la Respiration des Pois- sons, in Mem. de la Soc. d’Arcueil, tom. ii. 1809. Nysten, Recherches de Physiologie et de Cliimie Pathologiques, Paris, 1811. Legallois, Experiences sur le Principe de la Vie, Paris, 1812 ; and Memoire sur la Clialeur Animale, in Annales de Chimie et de Physique, tom. 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, Observations 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. JVasse, Untersuchungen uber das Athmen, in Meckel’s Archivfur Anatomie und Physiologie, Bandii. 1816. Coutanceau, Revision de Nouvelles Doctrines Chi- mico-Physiologiques, See., Paris, 1821. Dulong, De la Chaleur Animale, in Magendie’s Journal de Phy- siologie, tom. iii. 1823. IV. T. Edwards, De l’ln- fluence des Agens Physiques sur la Vie, Paris, 1824. Despretz, Recherches Expe'rimentales sur les Causes de la Chaleur Animale, in Annales de Chimie et de Physique, tom. xxvi. 1824; also in Magendie’s Journal, tom. iv. 1824. Scudamore, An Essay on the Blood, London, 1824. Herbst, Ueber die Capa- citat der Lungen fur Luft in gesunden und kran- ken Zustande, in Meckel’s Arehiv, Band xiii. 1828. Collard de Martigny, Recherches Experimentales et Critiques sur l’Absorption et sur l’Exhalation Re- spiratoires, in Magendie’s Journal de Physiologie, tom. x. p. 111. 1830 ; also, Recherches Experimen- tales sur 1’Exhalation Gazeuse 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. JR. and R. C. Tremranus, Versuche uber das Athmenholen der niedern Thiere, in Zeitsclirift fur Physiologie, von Tiedemann und Tremranus, vierter Band. 1831. Christison, 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 Physiologie, Band v. 1833. Maack, De Ratione qu® Colorem Sanguinis inter et Respirationis Func- tionem intercedit, Kilise, 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 Physiologie, 1845. Enschut, Dissertatio Physiologico-Medica de Respi- rationis Chymismo. Trajecti ad Rheniun, 1836. Bischoff, Commentatio de Novis quibusdam Expe- riments Chemico-Physiologicis ad illustrandam Doctrinam de Respiratione institutis. Heidelberg®, 1837. Magnus, Ueber die in Blute entlialten Gase, Sauerstoff, Stichstoff, und Ivolensauxe, in Poggen- dorffs Annalen der Physik und Chemie, Band xl. 1837 : Ueber des Absorptions vermogen des Blute fur Sauerstoff, in PoggendorfFs Annalen, Band lxvi. 1845. Maitland, Experimental Essay on the Blood, Edinburgh, 1837. Becquerel and Breschet, Re- 1 cherches Experimentales Physico-Physiologiques sur la Temperature des Tissues et des Liquides Ani- maux, in Annales des Sciences Xat urelles, 2me serie, tom. vii. 1837. Dr. John Davy, An Account of some I 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. Mi Gregor, Experiments on Carbonic Acid thrown off from the Lungs, in p. 87 of Transactions of the Sections in the Report of the British Scientific As • sociation for 1840. Leblanc, Recherches sur la Composition de l’Air confine, in Annales de Chim. et de Phys. tom. v. 1842. Mandl, Memoire sur les Alterations qu’eprouve le Sang pendant la Respira- tion, in Arehiv. Gener. de Med. 3me serie, tom. xiii. 1842. Beau and Maissiat, Recherches sur le Me- chanisme des Mouvements Respiratoires, in Arehiv. Gener. de Medecine, 3me serie, tom. xv. 1842, and 4me se'rie, tom. i. ii. and iii. 1843. Bourgery, Memoire sur les Rapports de la Structure intime, avec la Ca- pacity fonctionelle des Poumons dans les deux Sexes, et a divers Ages, in Comptes Rendus, 23me Janvier, 1843, and in Archives Generales de Medecine, 4me sdrie, tom. i. 1843. Thomson, The Chemistry of Animal Bodies, Edinburgh, 1843. Valentin and Brunner, Ueber das Verhaltniss der bei dem Athmen des Menschen ausgesehiedenen Ivolensauere zu dem dureh jenen Process aufgenommenen Sauerstoff, in Arehiv fur physiologische Heilkunde, von Roser und Wunderlich, Band ii. 1843 ; also Valentin’s Lehrbuch der Physiologie des Menschen, Band i. Braunschweig, 1844. Scharling, Versuche uber die Quantitat der, von einem Menschen in 24 Stunden ausgeathmeten, Kohlensaure, in Annalen der Chemie und Pharmacie von W ohler und Liebig, Band xiv. 1843. Fortgesetzte Untersuchungen zur Bestim- mimg der Quantitat von Kolensaure, welche ein Mensch in 24 Stunden ausathmet, in Annalen der Chemie und Pharmacie, Band Ivii. 1846. Andral and Gavarret, Recherches sur la Quantite d’Acide Carbonique exhale par le Poumon dans l’Espece Humaine, in Annales de Chim. et de Phys. tom. viii. 1843. Malcolm, Some Experiments on the Propor- tion of Carbonic Acid formed during Respiration in Typhus, in the London and Edinburgh Monthly Medical Journal, 1843. Dumas, Essai de Statique Chimique des Etres Organises, 3me edit. Paris, 1844. Enderlin, Physiologisch-Chemische Untersuchun- gen, in Annalen der Chemie und'Pharmacie, Band xlix. 1844. Boussingault, Analyses Comparees de 1’ Aliment consomme et des Excrements rendus par rme Tourterelle, entreprises pom rechercher s’ll y a Exhalation d’Azote pendant la Respiration des Granivores, Ann. de Chim. et de Phys. tom. xi. 1844. . Scherer, Ueber die Farbe des Blutes, in Zeitschrift fur rationelle Medizin, heraus-gegeben von Henle und Pfeufer, Band i. 1844. Brucli, Ueber die Farbe des Blutes, in Zeitschrift fur rationelle Medizin, Band i. 1844. Noch einmal die Blutfarbe, in same journal, Band iii. 1845. Das Neuste zur Gesehichte der Blutfarbe, in same journal, Band v. 1846. Hutchinson, 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, Ueber die Respiration derFrosche, in Journal fur praktische Chemie, von Erdman und Marchand, Band xxxiii. 1844. Ueber die Einwir- kung des Sauerstoffes auf das Blut und seine Be- standtheile, in same journal, band xxxv. 1845. Ueber die Anwesenheit der kolensauren Salze in dem Blute, in same journal, band xxxvii. 1846. Ueber die Farbe des Blutes, in same journal, Band xxxviii. 1846. Gay-Lussac, Observations Critiques sur la Theorie des Phenombnes Chimiques de la Respiration, in Annales de Chim. et de Phys. 3me serie, tom. xi. 1844. Hannover, De Quantitate relativa et absoluta Acidi Carbonici ab Homine sano et ®groto exhalati, ILauni®, 1845. Mendelssohn, Der Mechanismus der Respiration und Cirkulation, Berlin, 1845. Vierordt, Physiologie des Athmens, Karlsruhe, 1845. Article “ Respiration,” in W agner’s Handworterbuch der Physiologie. In Sachen der Respirationslehre. Noch eine Antwort an Herr P. Lowenberg in Berlin, in RODENTIA. 368 Zeitschrift fur rationelle Medizin, Band v. 1846. Ludwig, Einige Bemerkungen zu Valentin’s Lehren von Athmen und vom Blutkreislauf, in Zeitschrift fur rationelle Medizin, Band iii. 1845. Reuter, Be- leuchtung der Versucke von Prof. Scherer und Dr. Bruch uber die Farbe des Blutes, in Zeitschrift fur rationelle Medizin, Band iii. 1845. Letellier, In- fluence des Temperatures extremes de 1’ Atmosphere sur la Production de l’Acide Carbonique dans la Re- spiration des Animaux & Sang chaud, in Comptes Rendus, tom. xx. 1845, and Annales de Chim. et de Phys. tom. xiii. 1845. Mulder, Zur Frage, auf welche” Weise der SauerstofF der Lul’t bei der Respi- ration vom Blute aufgenommen wil'd, 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. Liebig, Ueber die Abwesenheit der kohlensauren Alkalien im Blute, in Annalen der Chemie und Pharmacie, Band lvii. 1846. Animal Chemistry, &e., edited by Dr. William Gregory, 3d edition, London, 1846. Moleschott, Versuche zur Bestimmung des Wassergehalts der vom Menschen ausgeathmeten Luft, in Hollandische Beitrage, &c., Band i. heft i. 1846. Snow, On the Pathological Effects of Atmospheres vitiated by Carbonic Acid Gas, 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 Pathologie und Physiologie, heraus-gegeben von Dr. L. Traube, Berlin, 1846. Harless, Monographic uber den Ein- fluss der Gase auf die Form 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 Iicid.) RODENTlA(G7iras, 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 office of chisels by cutting and gnawing away the hard vegetable substances, w hich (orm 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 iil-adapted to seize living prey, or to devour flesh, notwithstanding that certain genera of rodents exhibit decidedly carnivorous propensities. These incisors, also called dentes scalprarii, 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 gnawing. The molar teeth have their crowns flattened and traversed by plates of enamel, arranged transversely, the better to antagonise the backward and forward movement of the jaws. Fig. 247. 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 Squirrel) (Jig. 247.). Cheiromys (Aye-Aye). Arctomys (Marmot). Myoxus (Dormouse). Echimys. Hydromys. Capromys. Mus(Raf). Gerbillus. Meriones. Cricetus (Hamster). Arvicola (Vole). Fiber (Musk Rat). Geo- j rychus (Lemming). Otomys. Dipus (Jer- boa) (jig. 248.). Poephagomys. Helamys, Spalax (Rat Mole) (Jig. 249.) Bathiergus (Cape Mole) (Jig. 260.). Geomys. Diplo- stoma. Castor (Beaver). Myopotamus (Coni). Hystrix (Porcupine). Lepus (Hare). Lago- mys (Rat Hare). Hydrochoerus (Capybara) Bhyzomys. Cavia (Guinea Pig). Dasyprocta (Agouti). Ccelogenys (Paea). Chinchilla. RODENTIA. 369 Fig. 248. Spalax typlilus. Shull of the Hare. liarities in their arrangement, which it will be an evident approximation to what is found in necessary to notice. birds. Fig. 250. Bones of the cranium. — The bones of the mina are united into one, in fiont of which cranium in the Rodentia present several pecu- the sphenoid forms a single vertical lamella, Fig. 249. Fig. 251. Bathiergus maritimus. In the hare*, the anterior sphenoid is very The remarkable, inasmuch as the two optic fora- orbital * Cuvier, Anatomie coinpan'e, last edition. before and behind VOL. IV. os frontis presents a strong supra- crest, which is deeply notched both It advances on each side n n Dipus hersipes. 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 purietals 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 tympanic 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 tlescend 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 thefrontal bones is Iikewiseobliter- 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 consolidated 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 broader 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. Tlie 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 ( Bathiergus ) 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 deep notch, which exists on the external border of the occipital bone. The paramastoid apophysis is dilated into a prominent plate. 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 water 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 371 RODENTIA. 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 rests 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 I 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-. ■angement of the bones in the orbit resembles hat of the genus Mas. The tympana are extremely vesicular and prominent ; they iound posteriorly the glenoid cavity, which esembles a deep furrow. There are small aramastoid apophyses closely applied to hem. In the hamster ( Cricetus) the inter-parieta is a small triangular 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. In the rat motes ( Syntax ) 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 rliyzomys 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 1I0DENTIA. bones form a perfect cross; the inter-parietal bone is large and of a rhomboidal shape. In the alactaga {Mus jaculus, Lin.), a spe- cies of the same genus, the inter-parietal is Fig. 255. Skull of the Dipus hersipes. separated from the temporal by a broad pro- cess divided from the occipital, which runs to join the parietal, as in the gerbilles ( Gcr - billus, Desmar, Meriones, Ilig). The os petro- sura occupies a considerable space in the occipital region ; but in the jerboa {Dipus) 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. Anothernarrow band is derived from the sum- mit of the 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 tympanum, 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 alae do not ascend higher than the orbital, and remain widely separated from the parietal. In the eclnmys (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 only, 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 capromys 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 well 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 anehylosed 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 I 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 ( Cavia) the parietal RODENTIA. 373 bones and the inter-parietal, which 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 foramen lacerum anterius, 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 ( Myopotamus , Connnerson) 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 aim 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 capybara 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-pa rietals 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 the herodons, 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 u 3 374 R0DENT1A. 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 which 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 zygomatic 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 laminae, the ex- ternal of which is prolonged as far as the tympanum, 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 malte 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 w'ith 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, posteriorly', about one-fifth of the extent of the palate. After having formed the root of the pterygoid alas, 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 beaver , the post-orbital apophysis of the os malas 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 w'ell 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 water 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 alse 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 externally. 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 visible 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 alse 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 fissureof the maxillary bone. The points of the internal pterygoid apophyses do not reach as far as the tympanum. There is be- tween the pterygoid alas a membranous space. In the gerbilles, 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 by 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 concealing 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 ( Myoxus ), 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 ( Myoxus 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 inferiorly, and are proportionally of larger size than in orycteres. The process of the maxillary which surrounds the infra-or- bital bole 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 a/actaga, 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 little 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 paephagomys the jugal is broad, it gives off 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 lielamys 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 aim do not extend transversely beneath the foramen ovale. The eapromys 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 (Hystrix crhtata). In the common porcupine ( Hystrix crhtata, 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 prehensilh, 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, Comraer- 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 edge of its malar apophysis very much flattened. The 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. Guv. ; 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 aDophysis, a long oval sinus, into which, both before and behind, a rounded canal opens. Inferiorlv, the palate bone advances in a wedge-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 aim 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 paces ( Ccelogenus Fred. Cuv ; Cavia 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. 11ns swelling, which fills up a portion of the 378 RODENTIA. pre-orbital ring, causes the latter to be much elongated transversely. And towards its in- Fie. 258. Skull of the Ccelogymis. 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 ( Ancema , Fred. Cuv. ; Cavia, Ilig. ; Mus porcellus, 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 orbit, when it is connected with the lachrymal bone. In the palate it is very deeply notched. In the capybara ( Hydrochcerus , 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 aim 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 Capybara. tympanum. The palatine encroaches upon the palate as far forward as the third molar Fig. 260. Skull of the Chinchilla. a, b, c, portions of the temporal bone, which is here very remarkable on account of the extraordinary development of the tympanic cavity ; e, meatus auditorius externus ; f the occipital bone ; y, 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 hone ; /, 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 ; f 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 alas 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 tympanum. Bones of the carpus. — 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 th e 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, with which it is articulated. In the marmot and the agouti this rudiment is composed of three ossicles ; and there is, moreover, an internal supernumerary bone. Fig. 262. Skeleton of the Hare ( Lepus timidus). 110DENTIA. 380 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. Fig. 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. 264. 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 linea aspera ; in all the Rodentia the great tro- chanter is very prominent, and the neck of RODENTIA. 381 the thigh bone considerably narrower than its its posterior aspect there is likewise a promi- head. nent crest. It results from this structure, Fig. 263. Skeleton of the Paca ( Ccelogenys Paco). individuals are examined carefully, it is per- ceptible that the external malleolus is formed 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- Skcleton of the Jerboa ( Dipus hersipes). nal to the astragalus, to which is attached the {Altered from Pander and D’ Alton.) cuneiform bone" that supports the great toe, 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 ondatra. 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 Fig. 26G. The Rodentia have the fibula 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 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 spalaxand 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 helainys, 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 eapybara, 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 different 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 eapybara, the agouti, and the Guinea-pig both the inner and outer toes are reduced to a single bone. The jerboa (Mus jaculus) and the alactaga (Alns 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 dentes 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 jaws 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 consists 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, Odontography, 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 Fig- voles, the houtias (Cajorotnys), and the Cape jerboa {Helamys) . The genera which have molars, with short or incomplete roots, developed late, are Castor (beaver), liystrix (porcupine), Ccelogenys (spotted cavy), JDasyprocta (agouti). Spa/ax (blind rat), Myopotamus (coypa), Euryotis, Accomys, and Aplodontia. 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, 267. Lower jaw of the Porcupine (Hystrix cristata ). i, incisor tooth ; m, the molar teeth, implanted in the jaws by means of fangs ; i *, pulp at the base of incisor tooth ; p, anterior molar. 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. 2C8. Upper jaw of the Patagonian Cavy ( Chloromys Patagoniea'). i, 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 same advantage as the incisors, in the relief of the delicate tissues of the active vascular matrix from the effects of the pressure which would otherwise have been transmitted more directly from the grinding surface. The complexity of the structure of the crown of the molar teeth, and the quantity of enamel and cement interblended with the dentinp, are greatest in the rootless molars of the strictly herbivorous Rodents. The crowns of the rooted molars of the omnivorous rats and mice are almost as simple as the tuber- culate molars of the bear, or of the human subject, which they appear to typify. They are at first tuberculate ; when the summits of the tubercles are worn off, the inequality of the grinding surface is for a time maintained by the deeper transverse folds of enamel, the margins of which are separated by alternate valleys of dentine and cement ; but these folds, sinking only to a slight depth, are in time obliterated, and the grinding surface is reduced to a smooth field of dentine, with a simple border of enamel. A similar change in the grinding surface, consequent on age and use, is shown in the molars of the souslik, or ground squirrel ; as also in those of the gerbille, and is common to all that possess roots. It will be seen that these folds have a general tendency to a trans- verse direction across the crown of the tooth. Baron Cuvier has pointed out the concomitant modification of the shape of the joint of the lower jaw, which almost restricts it to horizontal movements to and fro, in the direction of the axis of the head, during the act of mastication. When the folds of enamel dip in vertically from the summit to a greater or less depth into the substance of the crown of the tooth, as in those molars which have roots, the con- figuration of the grinding surface varies with the degree of abrasion, of which examples have the Guinea-pig, the capybara, and the Pata- gonian cavy. The whole exterior of the molar teeth of the Rodentia is covered by a cement, and the external interspaces of the enamel folds are filled with the same substance. In the chin- chilidte and the capybara, where the folds of enamel extend quite across the body of the tooth, and insulate as many plates of dentine, these detached portions are held together by the cement ; such folds of enamel are usually parallel, as in the large posterior lower molar of the capybara, which, in shape and structure, offers a very close and interesting resemblance to the molars of the Asiatic elephant. The partial folds and islands of enamel in the molars of the porcupine and agouti, typify the structure of the teeth of the rhi- noceros ; the opposite lateral inflections of enamel in the molars of the gerbille and Cape mole-rat represent the structure of the molars of the hippopotamus ; the double crescenti' folds in the jerboa sketch out, as it were, the characteristic structure of the molars of the Anoplothere and Ruminantia. Although, as has been shown, the molar teeth in many Rodents are rootless and of un- limited growth, as in the Edentata, in none is enamel absent ; or vascular dentine, as the chief constituent of the tooth, present. These essential differences characterise the molars of those Rodents, which by use have their grinding surface reduced to a simple depres- sion bounded by a raised circular margin, as in the great Cape mole; that margin being formed by true enamel, but in the sloths by hard dentine. It is peculiar to some of the Rodents with rootless molars to have the sockets of these long curved teeth open at both extremities, so that, in the dry skull, the base of the tooth protrudes as well as the grinding surface ; the matrix in such instances adheres to the peri- RODENT1A. 385 osteum, which covered the portion of bone absorbed from the bottom of the alveolus. The jumping hare ( Helamys capensis ), 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 ( Lagomys ), has - — - ; the squirrels 5 5 have , — ; the families of the dormice, the 4 — 4 porcupines, the spring rats (Eckingidcc), the octodonts, chinchillas, and cavies, have 4—4 , . ^ j molars ; in the great family of rats ( Muridce ), the normal number of molars is 3 3 g — - ; but the Australian water rat ( Hydro - 2 9 mys) 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 ^ — j, 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 lower 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 upper jaw of a Rabbit, showing the effects of unchecked growth on the scalpriform 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 muscle 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 own 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 animal and vegetable substances forming the nutriment of some genera, whilst others live exclusively upon the fruit, bark, or leaves of c c 386 llODENTIA. 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 hursarius). 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 lined 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 ( Sciurus ) 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 lined internally with a thick epi- dermis, which forms 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 (Fiber, Cuv.), campagnols (Arvicola), and the lemmings (Georychus, llinger), present a similar ar- rangement. Fig. 271. Stomach of the Water Vole (Arvicola amphibius'). g, cesophagus ; 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 Hud- sonius, 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 tipper 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 (Dipus, Gm.), and in the leaping hares of the Cape (Helamys). 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 cylindrical pyloric portion, which is bent forwards. The rat moles (Spa/a. r, 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 muscardirt (M. 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 stomach 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 (Cricetus, 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 maritimus) has its stomach slightly different ; its position is more longitudinal, so that the left compartment is anterior, and the right posterior ; the piyloric 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 igoutis and the pacas. In the pteromys (F. Cuv.) the stomach is situated more transversely, and the two euls- de-sac are more distinct ; the right compart- ment is the largest, 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: these would seem to indicate traces of a division of the cavitv into three pouches. In the dormice ( Myoxus , 6m.) the stomach differs in shape in accordance with the appe- tites of the different species. In the common dormouse {Mus G/is, 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. I n MyoxusNitela, 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 ( Hystrix , Lin.) we have another example of the dif- ferences which the stomach may present in different genera. In the cuendu ( Synetheres , 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, cylindrical, and directed forwards, terminating by a ring, which projects into the intestine. In the European porcupine {Hystrix crista/a, 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 walls 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 ( Myoxus ), 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 allied 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 caecum is divided into compartments by a broad spiral membrane. In some species again, as in the jerboa, &c., the interior of the caecum 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. Fig. 272. Caecum of tlic Squirrel. a, termination of the small intestine ; h, 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 Stomach and intestinal canal of the Rat ( Mus Rattus). f, cesopliagus ; a, h, d, compartments of tiie stomach ; e, pylorus ; y, h, i, small intestine ; h, /, 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 Lcpns and Lagomys. In order to illustrate the above general description 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 ( Sciurus ) the small intestine (Jig. 272. a) is nearly of the same diameter throughout ; the caecum (b, c, d) is of mo- derate dimensions, of a conical shape, and destitute of any cells or partitions internally. Caecum of the Hare. c, termination of the ileum ; a, d, a spirally convoluted csecum ; b, d, its terminal glandular portion ; f dilated pouch, close to the termination of the small intestine ; e, capacious commencement of the colon’ which, at g, becomes considerably diminished in size. RODENTIA. 389 The colon ( e ) is for a short distance almost ol 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 papilias form small lamellae, the borders of which are fringed with 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 nearty 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. Ca.cum of the Water Vole ( Avicola ampliibius'). f, in, end of the small intestine ; n, o, p, q, csecum ; 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 amphibius ) 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 {Jig. 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 (/, mi) 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. [n the Cape moles {Bathiergus) the struc- ture of the caecum varies. In the orycterus of the Downs ( Bathiergus marUimus ) 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 {Bathiergus capensis ) the csecum 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 Fig. 275. c c 3 300 RODENTIA. three inches from its extremity {fig. 27 5.). 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 walls of which are thick and glandu- lar. At its commencement (od may be deposited as fat in those individuals who have a disposition to the production of adipose tissue ; but the azotised constituents cannot be applied in like manner to the unlimited increase of the mus- cular and other tissues ; and that which is not speedily converted into organisable material, and drawn off from the blood by conversion into organised tissue, would accumulate in- juriously in the circulating current, and would taint it by decomposition, if it were not con- tinually removed by the excreting processes. 5. Again, it cannot be deemed improbable that the changes which the crude aliment un- dergoes, from the time of its first reception into the absorbents and blood-vessels, to that of its conversion into organised tissues and into the materials of secretions eliminated for some special purpose in the economy, involve the liberation of many products, of which the elements are superfluous, and therefore injuri- ous to the system if retained within it. The condition of organic chemistry, however, is not at present such as to admit of anything beins advanced with certainty under this head. From these various sources, then, a large amount of effete matter is being continually received back from the tissues into the current of the circulation, or is generated in the blood by the changes to which it is itself subject ; and it is one great object of the secreting ap- paratus, to free that fluid of the products which would rapidly accumulate in it, but for the 458 SECRETION. provision which is thus made for their re- moval. The first product of the decay of all or- ganised structures is carbonic acid ; and this is the one which is most constantly and rapidly accumulating in the system, and the retention of which, therefore, within the bodv, is the most injurious. Accordingly, we find two organs, the lungs and the skin, specially des- tined to remove it ; and their action is so contrived, that whilst eliminating a noxious product, they shall be subservient to the in- troduction into the system of the vivifying element, oxygen, without a continued supply of which the animal functions cannot be long kept in activity, nor the heat of the body sus- tained. The skin, again, is one of the organs for the removal of the superfluous water from the body ; and the exhalation from its surface, the amount of which varies with the degree of external heat, serves the additional purpose of keeping down the temperature to its nor- mal standard. The lungs also regularly throw off a considerable quantity of water, of which the amount is but little subject to vari- ation, and of which some portion may have been actually generated in the blood by the union of hydrogen and oxygen. And the kidneys, the structure of which is beautifully adapted to eliminate the superfluous fluid by simple mechanical transudation, draw off the residue ; the amount of water which they re- move being the complement of that exhaled by the skin. All azotised substances have a tendency, during their decomposition, to throw off ni- trogen ,* and in the animal body this element is for the most part eliminated by the kidneys, entering largely into the composition of the urinary secretion. Thus we find urea to con- tain a larger proportion of nitrogen than exists in any other organic compound ; and uric acid, hippuric acid, kreatine and kreatinine, and other compounds, which are charac- teristic elements of this secretion in different animals, are all rich in nitrogen. Rut it is not only by the kidneys that azotised substances are thrown ofi, for the solid matter exuded from the skin closely corresponds in composi- tion with that of the urinary secretion ; and urea has been detected in it. The biliary secretion is peculiarly rich in hydrocarbon, and may probably be regarded as the complement of that of the kidneys ; it having been shown by Liebig, that if the em- pirical formula; for the bile and urine be added together, the result comes very near to the empirical formula for blood. Of this secre- tion, a part is certainly destined to be imme- diately carried off through the intestinal canal ; but another part seems to be re-absorbed, in combination with the fatty matters of the food, and to be subsequently thrown off by the respiratory process. What proportion is ap- plied to each purpose cannot be definitely stated, and probably varies much with circum- stances. But besides the metamorphosis of the or- ganised tissues, and of the organic elements of the blood, into the definite (generally crys- talline) compounds, which are the character- istic elements of the secretions already men- tioned, it would seem that a portion of the effete matters take on a putrescent state ; and that for the elimination of these a special and most appropriate apparatus is provided, namely, the extensive system of glandulae in the wall of the intestinal canal. As this point has been much less attended to than its im- portance deserves, it seems desirable to dwell upon it here in some detail. It has been too much the custom to regard the ftecal evacua- tions as little else than the indigestible re- sidue of the food, mingled with portions of the biliary and pancreatic secretions ; where- as we think that a little consideration will show, that the peculiarly fiscal matter is a real excretion, which must have been eliminated from the blood by the intestinal glandulte. The undigested residue of the food may form a greater or a smaller proportion of the bulk of the evacuation, according to the nature of the ingesta ami the completeness of the digestive process. When the alimentary canal is in an irritable state, and the aliment is hurried through it without time being allowed for the proper action of the gastric secretions, a con- siderable part of it may be recovered from the fieces in an almost unchanged condition. It has been found that even starch vesicles, if not ruptured by the masticating process, or by the heat employed in the preparation of the food, resist the digestive process so com- pletely as not to give up their contents ; being readily detectible in the feces, in an en- tire state, by the assistance of the microscope. Further, there is no evidence whatever, that the undigested residue of the food could ac- quire the fecal character, during the short period which suffices in the state of health tor its transmission along the alimentary canal ; and there is every reason to believe the contrary, since the substances which re- sist the action of the gastric solvent are pre- cisely those which have the least tendency to this kind of decomposition. Moreover, in purely Carnivorous animals, and in Man when he adopts the same diet, fecal matter is still voided, though in smaller quantity than in Herbivora. The case is still stronger in re- gard to sucking animals ; since the milk by which they are supported is pure nutriment, of which no part can be supposed to pass di- rectly into the feces. The continued evacu- ation of fecal matter when little or no food has been taken in, the large quantity brought off by purgative medicines after the bowels have been completely emptied of their solid contents, and the colliquative diarrhoea which so frequently occurs at the close of exhaust- ing diseases and previously to death by starvation, are so many obvious confirmations of the same view. And Dr. Williams* has pointed out many pathological phenomena, which indicate that the inflammation and ul- * Principles of Medicine, 2d ed. p. 248. note. ceration of the intestinal glandulae, which is so frequent a complication ot levers and of other diseases induced by the presence of a morbid poison in the blood, results from the continued operation, upon their own structure, of the noxious matter which these glandulae are endeavouring to eliminate from the system. This view has derived important confirma- tion from experiments recently made by Prof. Liebig ; these having indicated that the sub- stances to which the faeces owe their peculiar foetor may be artificially produced by the im- perfect oxidation of albuminous compounds.* The immense relief frequently given by an attack of diarrhoea, which spontaneously eli- minates morbific matters that were operating prejudicially on the system, and the corre- sponding effects of mild purgatives, which excite the secreting action of these glandulae, furnish additional evidence, if such be re- quired, to the same effect. It is obviously important in a therapeutic point of view, that definite ideas should be entertained on this subject ; and although it may be difficult to obtain positive proof of the position here ad- vanced, — that it is the special function of the glandulae of the lower part of the small intes- tines, and at the upper part of the large, to eliminate from the blood the putrescent matter which results from the disintegration of the tissues, — it will scarely be denied that a strong probability has been established by the foregoing evidence, in favour ot such a view. The interruption of any of these excreting processes, by causing an accumulation of effete matters in the blood, occasions speedy death (see Excretion); and Dr. Marshall Hall was perfectly correct in affirming f, that the functions of egestion are more immediately necessary to the maintenance of life than those of ingestion. For whilst most animals may live for a considerable time without food, and many without oxygen, there are none which are not speedily killed (unless pre- viously reduced to a state of torpidity) by the complete suspension of the excretory operations. In all the cases hitherto considered, the necessity for the secreting function arises out of the changes which are continually taking place in the system at large, and which tend to produce an injurious effect upon the cha- racter of the blood. We have seen, however, that even the act of liberation of effete or superfluous matters is frequently made to answer some ulterior purpose in the economy ; and we are thus led to notice the other class of secretions, in which this ulterior purpose appears to be the principal, it not the sole, ob- ject of their separation. The variety of these, however, is so great, and their uses are so different, that no general statement can be made regarding them. It must suffice to re- fer to a few examples, such as will show their importance in the economy of the different animals which form them. The secretion of tears for the cleansing and lubrication of the * Animal Chemistry, 3d ed. p. 154. j Gulstonian Lectures, 1842. TION. 459 surface of the eye ; the salivary, gastric, and pancreatic secretions for the reduction and solution of the food ; the mammary se- cretion for the nutrition of the offspring; the sebaceous secretions for the lubrication of the skin ; the mucous secretions for the protection of the mucous membranes ; the poisonous secretions of certain serpents, insects, &c. ; the glutinous secretion with which the silkworm weaves its cocoon anti the spider its web ; the pigmentary secretion of the cuttle-fish ; the colouring matter se- creted by the mantle of many of the mollusca for imparting various hues to their shells ; the strongly odorous secretions of many ani- mals, which seem generally attractive to those of their own kind, but repulsive to others ; together with many others that might be cited, are sufficient to indicate that the form- ation of even a very small amount of some peculiar product may be essential to the w ell- being of the animal which furnishes it ; by contributing to the due performance of one or more of its vital functions, or by the protec- tion it affords to some important organ. Existence of the elements of secretions in the blood. — The chemical proofs which have been recently obtained of the presence of the characteristic elements of certain secreted fluids in healthy blood, have afforded the most complete evidence of that which was previously highly probable, namely, that the office of the secreting organs is more that of selection and separation than that of conver- sion. The proof is most complete and satis- factory in regard to the chief elements of the urinary secretion ; but inferential evidence scarcely less conclusive exists with regard to several other substances. The presence of urea in the blood was first clearly shown by Prevost and Dumas*, who found that when the functions of the kidneys were destroyed, either by the extirpation of those organs, or by ligature of the renal ar- teries, urea could be detected in the circula- ting fluids after a short period. Similar re- sults have been obtained by other experi- menters ; and pathological observation, in cases where the normal secretion has been suspended or greatly diminished (as in the ad- vanced stages of Bright’s disease), has equally shown that under such circumstances the presence of urea manifests itself in the blood when duly analysed. f An interesting case has lately been put on record by Dr. Shear- man, in which the secretion of true urine being temporarily suspended, in consequence of accident (a watery fluid, containing neither urea, uric acid, nor the urates, being all that was passed for some days), urea was ob- tained in considerable quantity from the se- rum of blood drawn from the arm. J It would be difficult to explain such facts in any other way, than by supposing that urea is con- stantly being generated in the system, and * Annales de Cliimie, tom. xxiii. t See Christison in Edinb. Med. and Surg. Journ. 1829. J Edinb. Monthly Journal, March, 1848. 460 SECRETION. being received into the circulating current ; that being eliminated by the kidneys, in the state of health, as fast as it is formed, it has no time to accumulate in the blood ; but that when such elimination is checked or dimi- nished, whilst its formation continues, the minute quantity originally present gradually increases, so as at last to become easily de- tectible by chemical processes. However probable such an explanation might be felt to be, it is yet satisfactory to find it confirmed by direct experiment.* Simon and Marchand some time since obtained satisfactory evi- dence of the presence of urea in the healthy blood of the cow; and Dr. Garrod has lately succeeded in obtaining urea from the serum of healthy human blood. The amount, as might be anticipated, was very small, only l-200th of a grain of urea being procurable from 1000 grains of serum. f The pre-existence of uric acid in the blood might in like manner be inferred from the well-known fact of its deposition in gouty con- cretions : this inference, also, has been con- firmed by Dr. Garrod, who has discovered uric acid in the blood of gouty subjects. It might be not unreasonably asserted, however, that the presence of uric acid in the blood is the result of a disordered condition of the system generally ; and it is hence satisfactory to find that in this case also Dr. Garrod has succeeded in obtaining the substance itself from healthy blood. He states that the amount seems liable to considerable variation, and to have some relation to the period that has elapsed since food was last taken, being least where this was longest : thus in one in- stance, where food had not been taken for twenty-four hours, 1000 grains of serum yielded only 2-1000ths of a grain of uric acid ; whilst a similar quantity of serum from the blood of other healthy subjects yielded 7-1000ths ; and a like amount of serum from the blood of a man of full habit, but other- wise healthy, yielded 37-1000ths of a grain of uric acid. Of hippuric acid, which exists in small quantity in human urine, but in much larger amount in the urine of herbivorous animals, Dr. Garrod states (loc. cit.) that he thinks he has detected traces in the blood. There can be no reasonable doubt that /creatine and /creatinine are normal elements of healthy blood, since they are constituents of the “juice of flesh,” which seems to be the result of the disintegration of the muscular tissue, and must be taken into the circulating current to be conveyed from the muscles into the urine, where we again meet with these substances. In like manner it is probable that lactic acid * Dr. Prout states ( On Stomach and Penal Dis- eases, 5th ed. p. 531. note), that when engaged in examining the blood in the year 1816, he found urea (or a substance having most of its properties) in that fluid ; hut not crediting the fact, and think- ing it might be accidental, he did not pursue the enquiry, though he made a memorandum of the circumstance. f Lancet, July 8. 1848. is normally present in the blood in very mi- nute proportion ; for it abounds in the juice of flesh, and must be taken into the current of tlie circulation, in order to be eliminated from the body. In the healthy state it seems to be eliminated through the respiratory organs as fast as it is generated; being con- verted by oxidation into carbonic acid and water. It was formerly supposed to be a normal constituent of the urine; but it has been clearly proved by Liebig not to have a real existence there. Even when lactate of potash has been introduced by the stomach, the potash is thrown out by the kidneys in combination with other acids, the lactic acid not being eliminated in the urine, but passed off through the lungs. In certain dis- eased states of the system, however, lactic acid unquestionably presents itself in the gas- tric, urinary, and cutaneous secretions ; and as it has been shown to be one of the results of the disintegration of the muscular tissue, its pre-existence in the blood cannot be reason- ably doubted. The less definite nature of the constituents of bile prevents them from being as certainly re- cognised in the blood as those of urine have been ; nevertheless, the evidence of their pre- existence in the circulating fluids is sufficiently clear. Thus cholesterine may be obtained from the serum of the blood by an analytical process of no great complexity ; and its pre- sence there is also manifested by its occasional deposit, as a result of diseased action, in other parts of the body, especially in the fluids of local dropsies, as hydrocele, ovarian dropsy, &c. Again, the colouring matter of the bile seems to be nearly identical with certain normal elements of the blood, since the hue exhibited by a departing ecchymosis is identical with the characteristic colour of bde. In cases of jaundice, the presence of the colouring matter in the blood is often made evident, not merely by the communica- tion of its peculiar hue to the several tissues and secretions of the body, but also by the tint visible in the serum of the blood itself. It would seem probable, however, that in many of these cases there has been an actual re-absorption of the biliary matter subse- quently to its elimination by the Lver, as a consequence of obstruction to its exit by the gall duct. But in the most severe and ra- pidly fatal cases of jaundice, as pointed out by Dr. Alison*, the secreting process has never taken place, and the colouring matter must then have been generated in the blood itself. Neither cholesterine, nor the colouring matter of bile, seem to exert the poisonous influence on the nervous system which is manifested in the cases alluded to ; and it is probable that this must proceed from the accumulation of the peculiar organic constituent of the bile. As the precise nature of this, however, is still a matter of discussion amongst chemists, we cannot be surprised that it has not yet been obtained by analysis from the blood. * Edinb. Med and Surg. Journ. vol. xliv. 4G1 SECRETION. The proof that the constituents of the milk pre-exist in the blood, is rather inferential than direct. That the caseine (although so like the albumen of the blood that we might imagine it to be a mere modification of it, effected in the act of secretion) is, in reality, specially prepared in the circulating current, would appear from the fact that, during preg- nancy, a substance, kiestein, having a close relation to it, is eliminated by the urine, and that this substance disappears from the urine within a few days after parturition, the mam- mary secretion being then fairly established. Perhaps, however, the most remarkable evi- dence to the same effect is afforded by cases of metastasis of the mammary secretion, of which an account will be presently given ; and on the same kind of evidence rests the proof of the pre-existence of the other cha- racteristic elements of the mammary secretion in the blood. With regard, however, to the elements of other secretions, the evidence is less clear as to the state in which they exist previously to their elimination by the secreting apparatus. The fact would appear to be, however, that the solid constituents of most cf them are little else than constituents of the blood itself, either pure or but slightly altered. Thus in the lachrymal fluid, the saliva, the gastric and pancreatic juices, and the serous fluid of areolar tissue and of serous and synovial membranes, we find little else than saline matters, which are normal consti- tuents of the serum of the blood, with one or more organic compounds, that seem like albumen in a state of change. The repres- sion of these secretions does not produce any deleterious effect upon the general system, otherwise than as impairing or preventing the performance of the function to which they are subservient; whence it maybe inferred, that the selection of the secreted products from the blood is made in these cases, not for the sake of purifying the circulating fluid from any matter that would be noxious if retained, but merely for some minor purposes in the economy, to which these simple fluids are adequate. Metastasis of secretion. — Although the number and variety of the secretions become greater in proportion to the increased com- plexity of the nutritive processes in the higher classes, and although each appears as if it could be formed by its own organ alone, yet we may observe, even in the highest animals, some traces of the community of function which characterises the general surface of the lowest. It has been shown that, although the products of secretion are so different, the elementary structure of all glands is the same ; that wherever there is a free secreting surface it may be regarded as an extension of the gene- ral envelope of the body, or of the reflexion of it which lines the digestive cavity ; that its epithelium is continuous with the epider- mis of the integument, or with the epithelium of the mucous membrane from which it is prolonged; and that the peculiar principles of the secreted products pre-exist in the blood, in a form at least closely allied to that which they assume after their separation. Now, it may be stated as a general law in physiology, that in cases where the different functions are highly specialised (that is, where every one has its special and distinct organ for its own pur- pose alone), the general structure retains, more or less, the primitive community of function which characterised it in the lowest grade of develop- ment* Thus, although the functions of absorption and respiration have special organs provided for them in the higher animals, they are not altogether restricted to these, but may be performed in part by the general sur- face, which (although the special organ for exhalation) permits the passage of fluid into the interior of the system, and allows the in- terchange of gases between the blood and the air. In the same manner, we find that the functions of secretion being equally performed in the lowest animals by the whole surface, whilst in the highest there is a complicated apparatus of glandular organs, to each of which some special division of the function is assigned, either the general muco-cutaneous surface, or some one of its subdivisions or prolongations, is able to take on in some degree the function of another gland whose functions may be suspended. This truth was well known to Haller, who asserted that almost all secretions may, under the influence of disease, be formed by each and every secreting organ.' f This statement, however, needs to be received with some limitation, and it would be probably safest to restrict it to the excretions, whose elements pre-exist in the blood, and accumulate there when the elimination of them by their natural channel is suspended. We shall now consider some of the more remarkable examples of the me- tastasis of secretion. It seems to be established by a great mass of observations, that urine, or a fluid present- ing its essential characters, may pass off by the mucous membrane of the intestinal canal, by the salivary, lachrymal, and mam- mary glands, by the testes, by the ears, nose, and navel, by parts of the ordinary cutaneous surface, and even by serous membranes, such as the arachnoid lining the ventricles of the brain, the pleura, and the peritoneum. A. considerable number of such cases was col- lected by Haller J : many more were brought together by Nysten J ; more recently Bur- dach has furnished a full summary of the most important phenomena of the kind [| ; and Dr. Laycock has compiled a valuable summary of cases of urinary metastasis occurring as com- plications of hysteria.*)! The following table * See the author’s “ Principles of General and Comparative Physiology,” 2d ed § 243. f Elementa Physiologix, tom. ii. p. 369. + Ibid. p. 370. § Recherches cle Physiologie et de Chimie patho- logique, p. 265. |j Traitd de Physiologie (Jourdan’s Translation), voi. viii. p. 248, et seq. *1 Edinb. Med. and Surg. Joum. 1838. 4G2 SECRETION. of cases referred to by the last of these authors of the different forms of this curious affec- will give some idea of the relative frequency tion : — Vomit. Stool. Ears. Eyes. Saliva. Nose. Mammae. Navel. Skin. Total. 33 20 4 4 5 3 4 34 17 124 ft is to be borne in mind, however, that cases of hysterical ischuria are frequently compli- cated with that strange moral perversion, which leads to the most persevering and in- genious attempts at deceit ; and there can be little doubt that a good many of the instances on record, especially of urinous vomiting, are by no means veritable examples of metastasis. The proofs of the fact we are seeking to establish are, therefore, much more satisfac- tory when drawn from experiments upon animals, or from pathological observations, about which, from their very nature, there can be no mistake. Thus Mayer* found that when the two kidneys were extirpated in the guinea-pig, the cavities of the peritoneum and the pleura, the ventricles of the brain, the stomach, and the intestinal canal, contained a brownish li- quid having the odour of urine ; that the tears exhaled the same odour ; that the gall-bladder contained a brownish liquid not resembling bile; and that the testicles, the epididymis, the vasa deferentia, and the vesicufe semi- nales, were gorged with a liquid perfectly si- milar to urine. Chirac and Helvetius are quoted by Haller as having tied the renal ar- teries in dogs, and having then remarked that a urinous fluid was passed off from the sto- mach by vomiting. A remarkable case is quoted by Nysten from Zeviani, in which a young woman having received an incised wound on the external genitals, which would not heal, the urine gradually became more scanty, and at last none could be passed even with the assistance of the catheter ; at last dropsy supervened, with sweats of a urinous odour, and vomiting of a urinous fluid, which continued daily for thirty-three years. On post-mortem examination, the kidneys were found disorganised, the right ureter entirely obliterated and the left nearly so, and the bladder contracted to the size of a pigeon’s egg. In some other instances, the urine ap- pears to have been secreted, and then re-ab- sorbed in consequence of some obstruction to its exit through the urinary passages. Thus Nysten quotes from Wrisberg a case in which, the urethra having been partially obstructed for ten years by an enlarged prostate, the bladder was so distended as to contain ten pounds of urine ; and the serosity ot the pericardium and of the vesicles of the brain exhaled a urinous odour. He cites other in- stances in which the presence of calculi in the bladder prevented the due discharge ot the secretion ; and in which a urinous liquid was ejected from the stomach by vomiting, or was * Zeitschrift fiir Physiologie, tom. ii. p. 270. discharged by stool. A still more remarkable case is recorded, of a girl born without either anus or external genitals, who nevertheless remained in good health to the age of fifteen years, passing her urine from the nipples, and getting rid of fsecal matters by vomiting. There are cases, moreover, in which it would seem that the mucous lining of the urinary bladder must have had a special power of secreting urine ; the usual discharge having taken place to the end of life, when, as ap- peared by post-mortem examination, the kid- neys were so completely disorganised that they could not have furnished it ; or, having been prevented by original malformation, or by ligature of the urethra, from discharging it into the bladder. A considerable number of these have been collected by Burdach* In all the older statements of this kind, there is a defi- ciency of evidence that the fluids were really urinous, urea not having been obtained from them by chemical analysis, and the smell having been chiefly relied upon. The urinous odour, however, when distinct, is probably nearly as good an indication of the presence of the most characteristic constituent of hu- man urine, as is the sight of the urea in its separated form. The passage of a urinous fluid from the skin has been frequently ob- served in cases in which the renal secretion was scanty ; and the critical sweats, by which attacks of gout sometimes terminate, contain urates and phosphates in such abundance as to form a powdery deposit on the surface. It has lately been ascertained, that in warm climates urea is an element of the perspiration even of healthy persons. -f- The metastasis of the biliary secretion is familiar to every practitioner, as being the change on which jaundice is dependent. It is not, however, in every case of yellowish brown discolouration of the tissues, that we are to impute such discolouration to the pre- sence of biliary matter ; and we can only safely do so, when we have at the same time evidence of concurrent disturbance of the biliary apparatus. This disturbance may be of two kinds : either the secreting function of the liver itself may be diminished or sus- pended, so that the original elements of bile accumulate in the blood ; or, the secretion being formed by it as usual, its discharge may be prevented by obstruction of the gall-ducts, so that it is re-absorbed into the blood. The former condition is much the most dangerous of the two ; the re-absorption of the secretion after it has been once eliminated not being * Op. cit. pp. 263, 254. f Landerer in Heller’s Archiv. vol. iv. p. 196. SECRETION. 463 nearly as injurious as the cessation of the eliminating process. In either case, the uri- nary apparatus is the principal channel through which the biliary matter is eliminated ; the urine becomes tinged with the colouring prin- ciple of bile, being sometimes of a yellowish or orange hue, and sometimes of a brown co- lour with a considerable sediment ; and the presence of the most characteristic consti- tuents of the bile has been determined in the urine. The same result presents itself when the biliary duct has been artificially obstructed by ligature. Other secretions have been found tinged with the colouring matter of bile : thus the pancreatic fluid has been seen of a yellow colour in jaundice; and the milk has presented not merely the hue, but the characteristic bitterness, of the biliary secre- tion. The cutaneous transpiration is not un- frequently so much impregnated with biliary matter, as to communicate the tinge to the linen covering the skin ; and even the sputa of patients affected with bilious fevers have been observed to be similarly coloured, and have been found to contain biliary matter. The secretions of serous membranes, also, have been frequently seen to present the cha- racteristic hue of bile ; and biliary matter has been detected, by analysis, in the fluid of the pleural and peritoneal cavities. Biliary matter, however, when unduly pre- sent in the circulating current, is not removed from it by the secreting organs alone ; for it seems to be withdrawn also in the ordinary operations of nutrition, entering into combi- nation with the solid tissues. Thus, in per- sons affected with jaundice, we find the skin, the mucous and serous membranes, the lym- phatic glands, the brain, the fibrous tissues, the cartilages, the bones and teeth, and even the hair, penetrated with the colouring mat- ter of the bile, which they must have with- drawn from the blood, and which seems to have a particular affinity for the gelatinous tissues. Many instances are on record, in which the secretion of milk has apparently been trans- ferred from the mammary glands to some other surface. It might be expected, from what has been already stated regarding kies- tine, that the kidneys should eliminate the constituents of the secretion when the mam- mary glands are unable to do so. Several cases in which this happened are referred to by Voigtel.* One of these, strange to say, was a male , who was suffering under tume- faction of the mammary glands, accompanying an attack of catarrh. It is well known that the secretion of milk may be formed by the mammary gland of the male under particular circumstances ; but it could scarcely have been anticipated that it would be produced and eliminated through any other channel. A case has been recorded by Roller, however, in which this was unequivocally the case. A young man, suffering under various ailments, * Handbuch der Pathologischen Anatomie, tom. i. was affected with a vesicular eruption on the skin of the scrotum, which was considerably distended, and on the thighs ; and these ve- sicles discharged a large quantity of a whitish fluid, of somewhat spermatic odour, in which Lowig detected butter, caseous matter, sugar of milk, and alkaline and earthy salts. A fluid, having the appearance of milk, has also been transuded from the skin of the umbi- licus, of the axillae, of the groins, and of the back ; from the gastro-intestinal mucous membrane; from the mucous membrane of the genitals ; and from the surface of an ulcer. The following seems an unequivocal case of the vicarious secretion of milk by a very unusual channel. “ A lady of delicate constitution (with a predisposition to pneumonia) was prevented from suckling her first child, as she desired, by the following circumstance. Soon after her delivery she had a severe fever, during which her breasts became very large and hard ; the nipples were swollen and firm ; and there was evidently an abundant secretion of milk ; but neither the sucking of the infant, nor any artificial means, could draw a single drop of fluid from the swollen glands. It was clear that the milk-tubes were closed ; and as the breasts continued to grow larger and more painful, purgatives and other means were em- ployed to check the secretion of milk. After three days the fever somewhat diminished, and was replaced by a constant cough, which was at first dry, but soon after was followed by the expectoration of simple mucus. After this the cough diminished in severit}', and the expectoration became easy ; but the sputa were no longer mucous, but were composed of a liquid which had all the physical charac- ters of genuine milk. This continued for fifteen days, the quantity of milk expectorated amounting to three ounces or more in the twenty-four hours. The breasts gradually diminished in size ; and by the time that the expectoration ceased, they had regained their natural dimensions. The same complete ob- stacle to the flow of milk from the nipples re- curred after the births of four children suc- cessively, with the same sequel. After the sixth, she had the same symptoms of fever, but this time they were not followed by bron- chitis, or the expectoration of milk ; she had in their stead copious sweatings, which, with other severe symptoms, reduced her to a cachectic state, and terminated fatally in a fortnight.”* Although the menstrual flux cannot be re- garded in the light of an ordinary secretion, since it consists in great part of actual blood, yet there are indications that it is the means ol removing from the body something that is more injurious to it than a mere superfluity of the circulating fluid. A sudden suppression of the catamenia is frequently followed by symp- toms of constitutional disturbance, which neither general nor local abstraction of blood suffices to relieve, and which are only abated * Bidletino delle Scienze Mediche, Apr. 1839. 4G4 SECRETION. by tne restoration of the uterine flux, or by the establishment of a similar discharge from some other organ. Hence cases of vicarious menstruation may really be placed on the same footing with those of metastasis of secretion ; and they serve to illustrate and establish the same general truth. Such cases are by no means uncommon, the menstrual flux being replaced by haemorrhages from various parts of the skin, from the mucous membranes, or from glandular surfaces, especially the mammae. The following case, quoted by M. Brierre de Boismont* from the “ Medecine Pratique” of Pinel, is of peculiar interest from the variety of phenomena which it presents. “ Madlle A. had been subject, from the age of eleven, to attacks of hysteria, which were followed by vomiting of blood. She men- struated at fourteen ; her health was re-es- tablished, and the catamenia continued to flow regularly for several months. A sudden fright suppressed the menses, and again hys- teria came on. Vicarious menstruation now occurred. The legs swelled and were covered with vesicles, and during six months blood was regularly discharged from them. The left arm swelled, and the legs recovered ; and for a year there was a regular sanguineous discharge from the arm. A third deviation occurred from the left thumb, which had been slightly wounded ; the catamenia flowed from this opening for six months. In the fourth year two wounds were formed on the face from an attack of erysipelas ; one, on the side of the nose, the other on the upper eyelid. For two years the periodic discharge took place from these openings, and it no longer occurred from the thumb. The abdomen in its turn was attacked with erysipelas, and for five months regularly there was a discharge from the navel at each menstrual period. For four months the discharge proceeded from the inner ankle of the left foot; for two months from the left ear ; for three from the left nipple. When the discharge did not flow from any one part, bleedings at the nose and vomitings of blood took place, preceded by convulsions, pains in the head, and giddiness. After remaining some time at the Sal- petriere, the health of this young female im- proved, and regular menstruation was es- tablished.” It is probable that although the statement of Flaller, already quoted, is universally true as a possibility, yet that it is practically verified only in the case of the excretions, the mate- rials of which differ considerably from the nu- tritious elements of the blood, and accumulate in it when their usual exit-pipe is no longer open, forcing their way (so to speak) through other channels. If it be true, as we have suggested, that the materials of the recremen- titious secretions , as they have been termed, are nothing else than the materials of the blood itself, slightly modified for their special pur- pose in the very act of elimination, we see * De la Menstruation eonsideree dans ses Rap- ports Physio'.og-'ques et Pathologiques. why, when they are suspended, there is no accumulation of their materials in the circu- lating system, and no attempt at the sepa- ration of them by other organs. Influence of the nervous system on the secreting jtrocess. — That the eliminating ac- tion of the various secreting organs, and the amount and nature of their products, are greatly influenced by the conditions of the nervous system, cannot be doubted by any one who takes a general survey of the facts of this department of physiology. For although we can no more increase, diminish, or other- wise alter any one of our secretions by a mere effort of the will, than we can, “ by taking anxious thought, add one cubit unto our stature,” yet there is ample evidence that the state of the feelings has a powerful in- fluence upon many of them, increasing or diminishing their amount, or altering their character A' A brief review of the phenomena which manifest this influence, will serve as the most appropriate foundation for an inquiry into its nature and extent. The mammary secretion affords, perhaps, more remarkable evidence than any other, of the influence exercised over it by states of mind, in increasing or diminishing it, or in producing a complete change in its properties. Of the increase in the development of the gland at puberty, and still more during lacta- tion, no definite explanation can be given ; to say that it takes place by “ sympathy ” with the genital organs, being obviously a mere verbal evasion of the difficulty. But the ac- tivity of its function, w hen once it has been fully established, is mainly dependent upon the sensations and emotions connected with the act of suction, and with the thought of the offspring. Although the formation of milk may be constantly going on, yet it is greatly increased by the application of the infant to the breast. The quantity which can be squeezed from either breast at any one time, and the secretion of which may have occupied several hours, is about two ounces; and yet during a quarter of an hour’s suction, an in- fant may draw three or four times that amount', * True it is that there are cases in which secre- tions would seem to lie voluntarily produced, as when real tears are shed by performers on the stage, in the. personation of their assumed parts. But in such instances, a strict investigation of the mental state leads to the conclusion, that the emotions pro- per to the assumed character are for a time really felt ; the effort of the will being rather exerted in the change of individuality ( so to speak ) than in the production of the several movements of gesture or expression -which are significant of the mental state. And it is always observable that where the actor, possessing the requisite qualifications, can thus transform himself into the character he is per- sonating, so that his tones, looks, and gestures shall be the spontaneous and natural expression of his temporary feelings, he produces a much greater in- fluence upon the spectators, than he can do by the most careful voluntary realisation of his intellectual idea of the mode in which the character should be manifested. In these cases, then, as in all others, it is through the emotions, not directly by the will that the secretion is really excited. SECRETION. When the child is applied to the breast, a sudden turgescence is experienced in the organ, known to nurses as “the draught:” this is probably due to an increased afflux of blood, produced by the mental state, as in ordinary blushing. The “ draught ” will often take place, and the secretion begin to flow spontaneously from the ducts, at the mere sight of the infant, or at the thought of him when absent, especially if this be associated with the idea of nursing. Analogous phenom- ena are observed in domesticated Mammalia. Thus a good milch-cow will yield far more at a single milking, than the udder could have contained, so that the secretion must have been rapidly formed during the process. There are certain breeds of cows which will only yield milk when their calves are in sight; and in some instances if a calf should die, its skin is placed over a living calf, the presence of which has the same effect. The most curious instances, however, of the power of irritation of the nipple and of mental emotions to excite the secretion, are those in which its production has long ceased, or has never taken place. Numerous cases are on record in which young women who have not borne children, and even old women past the period of child-bearing, have had such a copious flow of milk, as to be able to act as nurses. In all these instances, the flow appears to have been brought on, in the first instance, by the con- tinued suction of the child, which had been applied to the breast to pacify it ; or by the influence of strong mental emotions, or by both causes combined. It has been lately mentioned by Dr. Me. William*, that the in- habitants of Bona Vista (one of the Cape de Verd islands) are accustomed to provide a wet nurse in cases of emergency, in the person of any woman who has once borne a child, and is still within the age of child-bearing, by continued fomentation of the mammas with a decoction of the leaves of th ejatropha curcas, and by suction of the nipple. Still more re- markable proofs of the same influence are furnished by the cases, of which several have now been narrated by credible witnesses, in which males have acted as efficient nurses. -j- The following, related by Dr. Dunglison £, is one of the most recent and at the same time most satisfactory upon record ; “ Pro- fessor Hall, of the University of Maryland, exhibited to his obstetrical class, in the year 1837, a coloured man, fifty-five years of age, who had large, soft, weil-formed mammas, rather more conical than those of the female, and projecting fully seven inches from the chest ; with perfect and large nipples. The glandular structure seemed to the touch to be exactly like that of the female. This man had officiated as wet nurse, for several years, * Report of the Niger Expedition. t See the case described by the Bishop of Cork in Phil. Trans, vol. xli. p. 813. ; one mentioned by Capt. Franklin (Narrative of a Journey to the Polar Sea, p. 157.) ; and one witnessed by Humboldt (Personal Narrative, vol. iii. p. 58.). t Physiology, vol. ii. p. 417. VOL. IV. 465 in the family of his mistress ; and he repre- sented that the secretion of milk was induced by applying the children intrusted to his care to the breasts during the night. When the milk was no longer required, great difficulty was experienced in arresting the secretion. His genital organs were fully developed.” Corresponding facts are also recorded of the male of several of the lower animals. The secretion of milk may be entirely checked by mental emotions, especially those having reference to the offspring. Thus a mother sees her infant in sudden danger, either from illness or accident ; the secretion is entirely suspended, and does not return until the child, having been restored to her safe and sound, is applied to the breast. The death of the infant will frequently occasion the sudden and complete cessation of the secretion. The same result will sometimes happen from powerful emotions unconnected with the infant : thus Sir A. Cooper mentions two instances in which the secretion, though previously abundant, was suddenly arrested by terror. It has been observed by medical men who practise much among the poor, that the apprehension of the brutal conduct of a drunken husband will put a stop for the time to the secretion of milk ; the breast feels hard and knotted, and flaccid from the ab- sence of the fluid ; and some time elapses before the proper amount returns. It may be stated, generally, that whilst a tranquil, cheer- ful state of mind has a tendency to increase the secretion, the depressing emotions diminish it. The mere increase or diminution of the secretion, from an influence communicated through the nerves, may possibly be accounted for by the influence they seem to exercise over the calibre of the smaller arteries, as shown in the act of blushing, to which “ the draught ” seems to have considerable resem- blance. But no such explanation accounts for the important fact, that not only the quan- tity but the quality of the milk is changed by mental emotions. Grief, anxiety, fits of anger, or a continual fretfulness, tend to render the milk thin and serous, and to impart to it qualities that excite intestinal irritation, griping, and fever in the child that ingests it. It might be difficult to detect any noxious elements in it by chemical analysis ; but the effect of the fluid upon the delicate system of the infant is a sure indication of their ex- istence. With this knowledge, derived from almost daily observation, we can have no reasonable ground for refusing to credit ac- counts of still more remarkable results pro- ceeding from the influence of mental emotion on the mammary secretion, such as the fol- lowing : — “ A carpenter fell into a quarrel with a soldier billeted iu his house, and was set upon by the latter with his drawn sword. The wife of the carpenter at first trembled from fear and terror, and then suddenly threw herself furiously between the com- batants, wrested the sword from the soldier’s hand, broke it in pieces, and threw it away. During the tumult, some neighbours came in H it 466 SECRETION. and separated the men. While in this state of strong excitement, the mother took up her child from the cradle, where it lay playing and in the most perfect health, never having had a moment’s illness ; she gave it the breast and in so doing sealed its fate. In a few minutes the infant left oft’ sucking, became restless, panted, and sank dead upon its mother’s bosom. The physician who was instantly called in, found the child lying in the cradle as if asleep, and with its features un- disturbed ; but all his resources were fruitless. It was irrecoverably gone.”* Such a case might be regarded as a mere coincidence if it stood alone ; but several others of similar character are upon record. Mr. Wardrop mentions f that having removed a small tu- mour from behind the ear of a mother, all went well until she fell into a violent passion, and the child being suckled soon afterwards, died in convulsions. He was sent for hastily to see another child in convulsions, after taking the breast of a nurse who had just been severely reprimanded ; and he was informed by Sir Richard Croft that he had seen many similar instances. Burdach cites two cases of a similar kind ; in one of which the infant put to the breast of its mother, just as she had received some very alarming intelligence, died in her arms before the eyes of the mes- senger; whilst in the other, the child having been nursed when the mind of the mother was in violent agitation, suddenly became extremely pale, and after some hours was attacked with paralysis on the right side, and convulsions on the left. Another of a very similar character has been more recently put on record. “ A woman while suckling her child became violently excited by the loss of some article which had been stolen from her. She gave her child the breast while in a state of violent passion. The child at first re- jected it, but subsequently took a quantity of milk. Soon afterwards violent vomiting supervened. In the course of some hours, the child took the other breast, when it was attacked with violent convulsions, and died in spite of medical aid.” j It will not be requisite to enter into similar details in regard to other secretions, the in- fluence of emotional states on which is a familiar fact. Thus the flow of saliva is stimulated by the sight, the smell, the taste, or even by the idea, of food ; whilst it may be entirely arrested by strong emotion, as is shown by the well known test often resorted to in India for the discovery of a thief among the servants of a family. All the parties being compelled to hold a certain quantity of rice in the mouth during a few minutes, the offender is generally distinguished by the com- parative dryness of his mouthful at the end of the experiment. The gastric secretion is greatly influenced by the emotional states * Dr. A. Combe’s Treatise on the Management of Infancy, p. 222., quoted from Dr. Von Ammon, “Die ersten Mutterpflichten und die erste Kinderspflege.” t Lancet, No. 516. t Casper’s Wochenschrift, 1845, S. 204. being usually increased by moderate exhilara- tion, and diminished by depression of the feel- ings. Any very strongemotion, however, usually suspends it for a time. The lachrymal secretion, which is continually being formed to a small extent for the purpose of bathing the surface of the eye, is poured out in great abundance under the moderate excitement of the emo- tions, either of joy, tenderness, or grief. It is checked, however, by violent emotions : hence in intense grief the tears do not flow. It is a well known proof of moderated sorrow when the flow returns : tears, however, do not bring relief, as commonly supposed, but they indicate that the violence of the emotion has passed off’. The odoriferous secretion from the skin, which is much more powerful in some individuals than in others, is increased under the influence of certain mental emo- tions, such as fear or bashfulness, and com- monly also by sexual desire.* That the formation of this secretion is due to changes occurring in the blood itself, and that the function of the cutaneous glandulae is rather to eliminate than to produce it, would appear from the fact that the characteristic smell of different animals may be detected in their blood when it is treated with sulphuric acid. The influence of fear or of sexual desire on the odoriferous secretions of many of the lower animals is well known ; the emission of a powerful and disgusting smell being not un- frequently a chief means of defence. The odoriferous matter is sometimes poured into the internal cavities, and discharged with the normal excretions, imparting to them its peculiar scent: thus the urine of a cat, voided under the influence of alarm, possesses a strong and disagreeable smell, which is with difficulty got rid of. The halitus from the lungs is in some persons so affected by mental emotions, that a piece of bad news shall almost instantaneously produce foetid breath. A copious secretion of foetid gas not un- j frequently takes place in the intestinal canal, under the influence of any disturbing emo- tion ; or the usual liquid secretions from its walls are similarly disordered. The tendency to defsecation, which is commonly excited under such circumstances, is not simply due therefore to relaxation of the sphincter ani, as commonly supposed, but is partly dependent on the unusually stimulating character of the faeces themselves. It is a prevalent, and, perhaps, not an ill-founded, opinion, that me- lancholy and jealousy have a tendency to in- crease the quantity, and to vitiate the quality, ■ of the biliary fluid ; and amongst the causes I of jaundice are usually set down the indul- ■ gence of the depressing emotions, or an access M * A series of glandulse in tlie axillary region, bearing a general resemblance to the sudoriferous H glands, but of larger size, have been supposed by H Prof. Horner (Amer. Journ. of Med. Sci. Jan. 1846 ), H and by M. Robin (Gaz. Med. Sept. 13. 1845), to be ■ specially concerned in the elimination of the pecu- jH liar odoriferous secretion of this region. These !jfj| glandulse have been shown by Prof. Homer to be ; M unusually large in the negro, whose axillary odour ■ is peculiarly strong. i H SECRETION. 467 of sudden and violent passion. There can itself. For we find, in the case of the pecu- be no doubt, however, that a disordered state iiar odorous matter for example, that it may of the biliary secretion is frequently rather be eliminated in a vaporous form by the air- the cause than the consequence of a melan- passages, or by the intestinal canal ; or that cholic state of mind ; the blood being suffi- its taint may be imparted to the liquid secre- ciently vitiated by a deficient elimination of tions of the intestinal glandulae ; or, again, bile, to have its due relations with the nervous that it mav be communicated to the urinarv system seriously disturbed, before any ob- vious indications of that deficiency make their appearance in the jaundiced aspect of the cutaneous surface. These and similar phenomena afford clear proof of the influence exerted over the secreting processes by mental states ; and it is scarcely to be imagined that this influence can be exerted through any other channel than the nervous system. If we further in- quire to which division of the nervous system we are to attribute the conveyance of this influence, we shall find reason to regard it as chiefly, if not entirely, operating through the portion commonly known as the sympathetic. For there are many secreting organs which are supplied with no other nerves than those which they receive from this division, so that they cannot possess any connection with the cerebro-spinal centres except through its medium. The mammary glands, which are supplied by the spinal nerves as well as by the sympathetic, may be considered as re- quiring such a direct communication with the cerebro-spinal centres, inasmuch as their se- cretion is made, for obvious purposes, greatly dependent upon sensations directly affecting themselves, which is rarely the case elsewhere. The lachrymal and salivary glands would seem to have a more direct and exclusive con- nection than most others, with the cerebro- spinal centres ; but perhaps this may be more apparent than real, for the fifth pair, from which they are supplied, seems in many re- spects to combine the attributes of a sympa- thetic with that of a proper cranial nerve ; and bearing in mind the minuteness and the universality of the distribution of the sympa- thetic plexuses upon the trunks of the blood- vessels, we see that even these glands, like others, may be subjected to its influence. If we further examine into the mode in which that influence is exerted, we shall, per- haps, find reason to attribute it to the effect of nervous agency, rather upon the walls of the blood-vessels and upon their contents, than upon the secreting structures themselves. For, as already remarked, the variations in the quantity of a secretion may be accounted for by such an increase or diminution in the access of blood as we know to take place, through an alteration in the calibre of the vessels, in the act of blushing or the paleness of fright ; and the feelings experienced by the nursing female harmonise well with this sup- position. On the other hand, the perversion ol the quality of a secretion, which may take place as a result of mental emotion, would seem rather due to an alteration in the con- stituents of the blood previously to the elimi- nation of the secretion, than to the exercise of any influence upon the secreting structure excretion : and this variety in the channels of escape of the same kind of material, pretty clearly indicates that it must have pre-existed in the blood. There are many other facts which confirm this view, by indicating that the condition of the blood whilst circulating in the vessels may be influenced by mental emotions, which probably act upon it through the medium of the sympathetic nerve ; but of these it is scarcely the place to speak. Another class of evidence, as to the ex- ertion of an influence by the nervous system upon the secretory function, is furnished by observation of the results of the interruption of that influence, either by a diseased con- dition of the nervous centres or nerve trunks, or by experimental interference. One of the most familiar of these, on account of its fre- quent occurrence, is the change in the cha- racter of the urine in cases of paraplegia ; resulting, as it would seem, from the secre- tion of an undue quantity of alkaline mucus from the lining of the bladder.* Various ex- periments have been made upon the nerves of the kidney, which seem to indicate that the normal secretion of urine is dependent upon their integrity. Thus Krirner j states, that division of any of the nerves of the kidney occasioned albumen and the red colouring matter of the blood to pass into the urine, their proportion increasing as that of the re- gular constituents of the urine diminished. Division of the vagus did not put a stop to the secretion of urine ; but rhubarb and prussiate of potass taken by the mouth ceased to pass off by the urine, which at the same time acquired greater specific gravity from containing serum of the blood. After divi- sion of the spinal cord in the dorsal or lumbar region, the urine became limpid like water; and division of the sympathetic nerve in the neck caused it to become alkaline and albu- minous. Brachet and Muller have both ex- perimented on the effects of the division of the sympathetic nerves which are distributed upon the renal artery. The former divided the trunk, and connected the divided ends by a canula, so as to allow of the continued passage of blood, whilst the nervous influence was completely intercepted ; the latter pro- duced the same condition by applying a liga- ture around the renal vessels, so tightly as to destroy the texture of the renal nerves at that point, and then relaxing it again, so as to permit the re-establishment of the circu- lation. In both cases the effect was similar ; the secretion of true urine being interrupted, but a sanguineous fluid passing into the * The nature of this change has been elsewhere considered. See Yol. III. p. 721 T. art. Nervous System. f Quoted in Muller's Physiology (Baly’s Trans- lation), p. 470. FI FI 2 468 SECRETION. ureter. Muller states that a remarkable softening of the kidney was always one of the results of these experiments. Numerous experiments have been made to determine the degree of dependence of the secretion of the gastric fluid upon the nervi vagi; to these experiments copious references have elsewhere been given*, and we shall therefore only here allude to their results. The temporary suspension of the digestive process appears to be an invariable result of the complete division of the par vagum on both sides ; and many of those who have witnessed this result have somewhat hastily concluded, that the secretion of gastric fluid is dependent upon nervous agency conveyed through that nerve. But it has been observed, in several instances, that the digestive powers have returned after a time, animals which were becoming much emaciated having re- covered their flesh ; and it is obvious, there- fore, that the secretion of the gastric fluid can not he dependent upon the supply of nervous agency through the par vagum, as some have supposed it to be. It is true, that in a large proportion of the experiments made to deter- mine this question, there has been no appear- ance of any return of the digestive power, after complete section of the par vagum on both sides ; but there are various modes of account- ing for this fact. The animals on which this experiment has been made, usually live for only a short time afterwards, on account of the disorder of the respiratory processes, which is one of the results of the operation ; so that all which is proved by the great bulk of the experiments is, that the digestive process is generally arrested during the short time that the animal lives after the vagi have been di- vided or tied. And such negative results, as Dr. J. Reid has very justly observed, “ can never overthrow the results derived from positive experiments, provided that these have been accurately performed, and are free from all sources of fallacy.” j- With these facts before us, it is much to be desired that the experiments just cited, as to the influence of section of the renal nerves upon the secretion of the kidney, had been sufficiently prolonged to ascertain whether the effects described are transient, and whether the real secretion would be restored if time were permitted. And it is obvious that, as they at present stand, no such experiments can serve as an adequate foundation for the hypothesis entertained by some, that the act of secretion is dependent upon nervous in- fluence, or, in other words, that nervous agency supplies a condition without which it cannot take place. There is another group of phenomena bear- ing upon this question, though less 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 tooting 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 organ or tissue receives, depends upon its functional activity; and thus not merely the muscles, but all the textures of a paralysed limb gradu- ally waste away, the disuse of its muscles occa- sioning a stagnation in the circulation through the entire part. Of the former result it is ne- cessary' to make a careful examination, that we may be prepared to estimate it at its true value. One of the cases most frequently quoted in this connection, is the effect of section of the trigeminus in producing destruc- tive inflammation of the eye-ball, as first shown by Magendie, and confirmed by many sub- sequent experimenters. A full account of these effects has been already given in another part of this work (see Fifth Pair), and it is therefore unnecessary to repeat them here. A corresponding result may be produced by disease. A case is related by Mr. Stanley*, in which there was impairment of the whole nutrition of one side of the face, with frequent attacks of erysipelatous inflammation, bleeding from the nose, central penetrating ulceration of the cornea, and, at last, destructive inflam- mation of the tunics of the eye, in consequence (as it would appear) of destruction of the trunk of the trigeminal nerve of that side by the pressure of a tumour near the pons. No such destructive effects ensue on section of any of the other cranial nerves ; the only injurious influence exercised on the eye by any such operation, being the tendency to inflammation from irritants which the para- lysed orbicularis palpebrarum does not shut ■ out or help to remove. But, on the other hand, cases are occasionally to be met with (of which the author has himself witnessed more than one) of the complete paralysis of the ophthalmic division of the fifth pair, which has existed for some time without any other result than a degree of dryness of the surface of the eye from deficient secretion, and a disposition to superficial inflammation from irritating par- ticles of whose presence no warning was given by sensation, and for whose removal there was consequently no provision. Such exceptional cases must be admitted as proving that, however unfavourable may be division or injury of the trigeminus to the continued healthy nutrition of the eye, still this may. be maintained ; and that it is consequently no more essentially dependent upon “nervous influence,” supplied through that channel, than is the secretion of gastric fluid upon the * Vol. III. p. 000. art. Pak Vagum, f Ibid. * Medical Gazette, vol, i. p. 531. SECRETION. 4-69 power supposed to be transmitted by the par vagum. That the nutritive operations of other parts, however, are usually less vigorously and cor- rectly performed when the nerves have been paralysed, than when they retain their entire integrity, would appear from numerous other facts, of which the following are examples. A case is related by Mr. Swan* * * § in which a man’s wrist having been injured by a cord having been very tightly drawn round it, there was partial paralysis of the hand, with constantly repeated ulcerations of its dorsal surface ; and on amputation seven years afterwards, there was found to be induration of the median nerve, with adhesion of the tissues beneath the annular ligament. The following case, stated by Mr. Paget f on the authority of Mr. Hilton, is still more remarkable. “ A man was at Guy’s Hospital, who, in consequence of a fracture at the lower end of the radius, re- paired by an excessive quantity of new bone, suffered compression of the median nerve. He had ulceration of the thumb, and fore and middle fingers, which had resisted various treatment, and was cured only by so binding the wrist, that the parts on the palmar aspect being relaxed, the pressure on the nerve was removed. So long as this was done, the ulcers became and remained well ; but as soon as the man was allowed to use his hand, the pressure on the nerves was renewed, and the ulceration of the parts supplied by it returned.” That the reparative processes are affected, as well as those of ordinary nutrition, by the loss of nervous power, is a matter of familiar ob- servation. A striking example to this effect is mentioned by Mr. Travers. J A man was rendered paraplegic by fracture of the lumbar vertebrae, the same accident having also frac- tured his humerus and his tibia. The former, in due time, united ; the latter did not. This peculiar affection of the nutritive pro- cesses appears rather dependent upon lesion of the sensory than of the motor nerves. Thus we have seen that the disorganisation of the eye after section of the fifth pair, takes place when only the sensory nerve of the part is affected, and that no such result occurs when only the motor nerves of the orbit are divided. In cases of disease or injuries of the spine, it has been noticed that sloughing of the blad- der or other parts has occurred earlier and more extensively when sensation, than when motion alone, has been lost. And Mr. Cur- ling has noticed § that two men having been taken at nearly the same time to the London Hospital with injury of the spine, one of whom had lost only the power of motion in the lower extremities, whilst the other had lost both motion and sensation, at the end of four months the atrophy of the lower extre- mities had advanced much further in the latter case than in the former. These phenomena * On Diseases and Injuries of the Nerves, p. CO. f Loc. cit. t Further Inquiry concerning Constitutional Ir- ritation, p. 436. § Med. Chirurg. Trans, vol. xx. p. 342. would seem to harmonise with the view, that it is especially through the sympathetic system of fibres that the peculiar influence is exerted, whose continual agency we only recognise by the results of its withdrawal. For if, as already remarked, the fifth pair may be con- sidered as the sympathetic of the head, the Gasserian ganglion may probably be regarded as belonging to the sympathetic system ; and it has been observed by Magendie, and con- firmed by Longet, that the destructive inflam- mation of the eye ensues more quickly after division of the trigeminal nerve in front of the Gasserian ganglion, than when the division is made between that ganglion and the brain. If this be true of the Gasserian ganglion, it is probably true, also, of the ganglia on the posterior roots of the spinal nerves ; and thus the disordered nutrition which results from in- jury to the trunks of these nerves, and which is not to be accounted for by the mere disuse of parts, may be attributed, with some show of probability, to the interruption of the connec- tion with the sympathetic system, which is specially established by these ganglia and their communicating cords. But it is to be remembered, on the other hand, that defec- tive or disordered nutrition is a marked resulf of injuries of the spinal cord, whilst the sym- pathetic centres remain uninjured ; and that general atrophy is a frequent consequence of chronic diseases of the brain. Fresh evi- dence is much required, therefore, to deter- mine the relative shares of the cerebro-spinal and sympathetic centres, in regard to the in- fluence exerted by them over the organic functions. By the survey we have now taken, we are in some degree prepared to estimate the degree and nature of the influence exerted by the nervous system on the nutritive and se- cretory functions, and to inquire into the validity of the several doctrines which have been propounded on the subject : — 1. The first of these theories may be stated in the words of Dr. Wilson Philip, one of its most distinguished advocates : — “ It appears,” he says, “ that the nervous influence is neces- sary to the function of secretion. It either bestows on the vessels the power of decom- posing and recombining the elementary parts of the blood, or effects those changes by its direct operation on this fluid. From many facts stated or referred to in my inquiry, it appears that the vessels possess no powers but the muscular and elastic ; and that the former, as well as the latter, is independent of the nervous system . Nor is it possible to con- ceive any modification of these powers by which they could become chemical agents, and thus be enabled to separate and recom- bine the elementary parts of the blood. The first of the above positions may, therefore, be regarded as set aside, and the necessary infer- ence seems to be, that in the functions of secretion the vessels only convey the fluids to be operated on by the nervous influence.” It will, perhaps, be sufficient to say of this hypothesis, that having been put forth at a H H 3 SECRETION. 470 time when the real nature of the secreting structure was altogether unknown, and when the choice seemed to lie only between the in- fluence of the nerves and that of the vessels, it is totally fallacious now that a third agent has been discovered, to which all analogy would lead us to refer, at any rate, the chief instrumentality in the operation. The prin- cipal experiment adduced in support of this hypothesis, and of the identification attempted by Dr. Philip between nervous agency and galvanism, was the effect of section of the par vagum in checking the secretion of gastric fluid, and the renewal of the process under the influence of galvanism. We have already shown the utter invalidity of this result as a ground for any such inference; and it only remains to show the inconsistency and insuffi- ciency of the hypothesis itself, which is easily done. For, as Dr. Prichard has justly re- marked *, “ if we begin by supposing the ex- istence of the cause assigned, we shall find that there is one agent, namely the galvanic fluid, operating on one material, which is the blood, and effecting its decomposition. How, then, we may ask, does it happen that so many different substances are, in different examples of the same process, the results of this single operation ? In other chemical de- compositions, as when water is decompounded by the galvanic fluid, the result is the same and uniform. But in the instance supposed, the operation of the same chemical agents upon each other is followed by the formation of products of the most different descriptions : in one part of the vascular system the blood is converted into bile ; in another, by the operation of the same chemical agent, into milk ; in another, into tears.” This variety of effects can only be explained by attribut- ing them to the special endowments of the several secreting organs through which the nervous power is supposed to act ; and if it be thus necessary to admit that such special endowments do exist, by which the particular nature of the secretion is determined, the question naturally arises, Of what use is the nervous power at all ? 2. The second hypothesis, framed to meet this objection, supposes, to use the language of Prof. Muller, that “ the influence of the nerves on the glands merely enables the se- creting substance, in each gland, endowed with peculiar properties, to exert its chemical ac- tion.” In order to sustain this hypothesis, it is necessary to show that the processes of secretion and nutrition are not only modified by the division of the nerves by which their organs are supplied, but that they are alto- gether suspended by that operation ; the secreting or growing structures having no functional power of their own, save when connected with certain nervous centres, which are supposed to transmit to them the requisite vital force : much as in a factory there may be seen a great variety of machines, each of * Review of the Doctrine of a Vital Principle, p. 198. them constructed to perform a certain special action, but all of them dependent for their power of carrying it into effect upon a general motive power transmitted to each. We shall, perhaps, more conveniently and satisfactorily examine into the merits of this hypothesis, by bringing it into comparison with the next. 3. The third doctrine, of which Dr. Alison has been one of the most philosophical and consistent advocates, is to the effect that the whole organic or vegetative life of animals, — i. e. every thing which goes on in them with- out the intervention of any sensation or other mental act, including the functions of nutrition and secretion, — may go on without the in- tervention of the nervous system, and stands in no relation of dependence to any changes in nervous matter ; but that these changes exert a powerful controlling and modifying influence on the organic functions, increasing or dimi- nishing their activity, or even altering their character ; just as, to use the appropriate illus- tration of Dr. John Reid, the movements of a horse are influenced by the hand and heel of the rider, although they are in themselves in- dependent of him, being executed in virtue of the power inherent in the animal. Now, in support of this last view of the subject, it may be urged, in the first place, that in one great division of the organised world, namely, in the vegetable kingdom, the functions of nutrition and secretion are per- formed, not only independently of, but with- out any kind of influence from, a nervous system ; each act being the result of the pro- perties inherent in the several parts of the structure itself, called into play by the appro- priate stimuli. We should have a right to expect, therefore, that the corresponding func- tions in animals should be adequately per- formed by a similar mechanism ; and it is fair, therefore, to throw the burthen of proof upon those who maintain the contrary. If we fol- low out in this case the great general principle of Cuvier, which every day’s experience only shows to be more strictly correct and more widely applicable, — that the different classes of animals may be considered as so many ex- periments ready prepared for us by nature, who adds to ‘or takes from their several organs, just as we might wish to do in our laboratories, showing us at the same time the various results of these combinations, — we see that a comparison of different organisms affords us a much better ground for the de- termination of this question, than can be ob- tained from the results of such experiments as have been already cited ; it not being pos- sible to make such experiments, without such injury to the organism as is of itself a serious disturbing cause. We notice, on looking at the highest animal, that the organic functions are brought into very close relation with the animal powers, and are liable to be consider- ably modified by the exercise of the latter. But, as we descend the scale, we find the nervous system constituting a less and less predominant part of the organism, and the apparatus of organic life becoming more and SECRETION. more disconnected from it ; until, in zoo- phytes, we are scarcely able to distinguish a nervous system at all, whilst all the operations of growth, nutrition, and secretion take place very much as in plants, in which no nervous system exists. Thus we find that “ the ner- vous sj'stem lives and grows within an ani- mal, somewhat as a parasitic plant does in a vegetable,” deriving its nutriment from the structure in the midst of which it is deve- loped, and capable of exercising a certain ac- tion upon it, but being strictly a superadded part, and having rather an adaptive than an essential connection with that structure. Now this view has derived from late dis- coveries in minute anatomy, as complete a confirmation as any such facts are capable of affording. For it has been shown, not merely that the functions of nutrition and secretion are common to animals and plants, but that the component elements of the organs by which they are performed are in both instances essentially the same. We have seen that the act of secretion is effected, even in the most complex gland, bv the agency of aggregations of ceils, each of which lives for and by itself, and appears to be dependent upon no other external conditions, than those which are re- quired for the growth of the simplest cellular plant, namely, food and warmth. And it is difficult to conceive how, over that most es- sential part of the secreting process — the de- velopement of the secreting cells — the ner- vous system can exert any direct influence. Another natural experiment, whose imme- diate bearing is rather upon the physiology of nutrition than upon that of secretion, but which is really as conclusive in regard to the latter as the former, is exhibited to us in the early growth and developement of the em- bryonic structure ; which makes considerable progress, especially in invertebrated animals, before any trace of the nervous system can be detected. And in the human species the case is not unfrequent, of the foetus coming to its full size with the usual variety of textures in its composition, but without either brain or spinal cord. It has been said, however, that in such instances the ganglia of the sympa- thetic system probably exist, and supply the influence supposed to be needed; but there are cases on record, in which these would seem to have been carefully looked for and not de- tected.* Ancj moreover, even if their uni- form presence were to be admitted, and the power of sustaining the operations of nutri- tion and secretion be supposed to reside in them, how are we to explain the effects of in- juries of the brain and spinal cord, the gangli- onic centres being left intact ? We can see no other consistent account of these phenomena, than that which is presented by the last of the three hypotheses enumerated ; the functions of nutrition and secretion (like the contrac- tility of muscular fibre) not being regarded as dependent for their ordinary exercise upon any power supplied by the nervous system, 471 but being considered to be modified by causes operating through it. And that this is the true view of the mat- ter, would further appear from a careful exam- ination into the nature of the phenomena which follow the section or injury of nerve- trunks or centres, and which have been supposed to indicate the impossibility of the continuance of true nutritive operations after the withdrawal of the hypothetical nervous influence. In the first place, the etfect pro- duced by section of those nerves which are supposed to exert the greatest influence, is probably not in any case a simple suspension of the nutritive operations, nor a death of the part ; but it is of the nature of inflam- matory action, involving disordered nutrition and perverted secretion. Further, this dis- ordered condition does not seem to be the direct result of the paralysis of the nerves, so much as an indirect consequence of the want of power to resist morbific causes. “ If' the section of the sensitive nerves of a part,” it has been observed (with special reference to the inflammations of the eye, the lungs, and stomach, consequent upon section of the fifth pair and par vagum), “ were the direct cause of its inflammation, we should expect to see in- flammation in all parts of which tne sensitive nerves are cut ; whereas the phenomenon in question is seen only in a few parts ; and in those parts it originates, and is chiefly seated, in a single texture, viz. the mucous mem- brane : that membrane is distinguished from others in the body by its power of bearing the contact of air, of foreign substances, and of excretions elaborated within the body, with impunity. This power seems obviously con- nected with its vital power of throwing out, when irritated, a mucous secretion, which protects it equally as the cuticle protects the true skin ; and this adaptation of the quantity of protecting mucus to the irritation which may act on a mucous membrane, may be very naturally supposed to depend on its sensi- bility, and to cease when its sensitive nerves are divided, and allow the mucous membrane to inflame and slough, equally as a serous membrane would do from the irritations which, in the natural state, excite only a healthy action upon it. On this supposition, the inflammations in question depend, not simply and directly on the division of nerves, but on the action of the air, the food, the bile, &c., on mucous membranes deprived of their sensibility, and thereby in great measure of their protecting mucus ; and bear an analogy to the inflammations of the same membranes which frequently take place from deficiency of the mucous secretion, in cases of death by starvation, and towards the close of lingering and exhausting diseases.”* And lastly, even supposing the inflammatory changes to be the direct result of the paralysed state of the nerves, they in themselves afford conclusive evidence against the doctrine, that the nervous influence is essential to the nutritive and * Brit, and For. Med. Rev. vol. iii. p. 14 H It 4 * Elber, de Acephalis, pp. 31. 35. 45. 172 SEMEN. secretory operations ; for, as Bichat observed, respecting the inflammation and suppuration of the testicle after its complete isolation from the larger masses of the nervous system, the establishment and maintenance of a morbid secretion was just as conclusive evidence of the independent character of the process, as if the normal product of the testis had been continued.* Upon all these grounds we feel justified in asserting, that no adequate ground has yet been furnished by pathological observation and experiment, for the establishment of any other doctrine as to the relation between the nervous system and the organic functions, than the last of those just stated. It is perfectly conformable to the facts supplied by com- parative physiology, and by the history of developement ; and may be said to rest upon them as upon a broad foundation. It har- monises sufficiently well with the results of experiment and pathological observation on man and the higher animals, to be considered as giving the most satisfactory interpretation of them which, in the present state of our knowledge, seems likely to be attained ; and if it be not the whole truth, is evidently not far from it. On the other hand, the doctrine that nervous influence is essential to the per- formance of the nutritive and secretory oper- ations, is opposed to the mass of phenomena presented in the vegetable world, in the lower tribes of the animal creation, and in the his- tory of the developement of the higher ; to the exact knowledge we now possess of the structure of glands themselves ; and even to the results of those experiments and patho- logical observations which have been relied upon to prove it, when these are carefully sifted. (W. B. Carpenter.') SEMEN. — Sperma ; Sperm, Engl.; Gr. inrepfia ; Germ. Samen ; Fr. Sperme. — Male animals, when perfectly developed and capable of procreation, secrete a thickish white fluid in their testicles, which possesses the faculty of inciting the generative parts of correspond- ing female individuals to a series of processes, the ultimate result of which is the developement ot the embryo. This fluid, so indispensably necessary as the medium of sexual generation, is the seed or semen. Histological elements of the semen. — Mi- croscopic analysis proves that the most essen- tial morphological constituent of the semen consists in the spermatozoa (animalcula sper- roatica), a number of corporeal elements, dis- tinguished by their specific shape, and by their pecul ar phenomena of vitality. The attention of physiologists and others has been actively directed towards them, ever since their dis- covery by Ham and Leuwcnhoek ; and the most varied and frequently the wildest assumptions and conjectures have been occasioned in con- sequence. In spite of the intimate relation w hich they evidently occupy with regard to the procreative capacity of the semen, they * Anatomie Gdne'rale, tom. iv. p. 604. have been considered, even up to the most recent period, as independent animal orga- nizations, or parasitical animals. The reason adduced for such a conjecture is the peculiar motion which may be observed in almost all of these formations, and which in many cases bears a striking resemblance to voluntary mo- tion. This assumption, however, is perfectly irreconcileable with our present knowledge of the quality and developement of these bodies, based as it is principally upon the discoveries of R. Wagner, Von Siebold, and Kdlli/cer. With our present means of a scientific diag- nosis, it can be proved that the formations in question are mere elementary constituents of the animal organization, like the ova, consti- tuents equally as necessary for the spermatic fluid as the blood-globules are for the blood. The remarkable phenomena of the life of sper- matozoa are quite analogous to those pheno- mena of motion observable not only in animal formations, but also in vegetable structures; as, for instance, in the spores of the algae and of the lower species of fungi, in the so termed vibriones, which grow out into the fibres of the conferva called “ hygrogrocis.” The denomination of “ animalcula sperma- tica, spermatozoa,” is based upon the assump- tion that these moveable elements of the semen are animated organizations endowed with all the attributes of animals ; and they were, ac- cordingly, classified among the Infusoria or Helminthea. Kolliker *, the first who most distinctly expressed the assertion that the so called spermatozoa are mere elementary parts of the organization, mere histological ele- ments, applied to them the name o 1 fila sper- matica; a designation which w'ould certainly be appropriate, if all the formations in ques- tion possessed a linear form. V. Siebold f, rejecting the old name on the same grounds, has proposed that of spermatozoides, which, however, we consider as still less happily chosen. We confess that we cannot exactly see the necessity of creating a new designation for these spermatic elements at all, the less so as many names in our scientific nomen- clature specify something quite different from that which they immediately indicate. We shall therefore principally use for the future the old name of spermatozoa, admitting at the same time that it is not quite a suitable one, and that it might probably be better expressed by the designation of corpuscula seminis, or spermatococci, by which they have occasion- ally been distinguished. The spermatozoa, or corpuscula seminis, are not merely normal, but in fact the essen- tial constituents of the procreative semen. Indeed, it appears, in many cases, espe- cially among the lower animals, that they are its only constituents. The presence of a fluid, liquor seminis, to hold them in sus- * Beitriige znr Kenntniss der Geschlechtsver- haltnissen and der Samenfliissigkeit wirbellosen Thiere. Berlin, 1841. f Uber die Spermatozooiden der Locnstinen. From the Acta Acad. Leop. Carol. Nat. Cur. vol. xxi. Part I. S. 1. SEMEN. 473 pension, is not perceptible in these cases ; and it would be perfectly unnecessary, when pro- creation takes place, without sexual connexion, in the water. The presence of such a medium can certainly not be denied among the verte- brata; but it remains to be proved whether it is of specific importance to the semen, or whether it does not perform a subordinate part both in a histological and physiological point of view. It is not quite improbable that the presence of this liquor seminis is merely incidental, and that it stands in a certain connexion with the process of developement'*, and perhaps also with the formation of the spermatozoa. In a phy- siological point of view, it may perhaps serve as the medium of a more easy and safe trans- mission of the spermatozoa to the ovaries. It may form for the spermatozoa a medium, which serves partly for the better develope- ment of their peculiar motions, and partly to afford them an immediate protection against the external influence of many in- jurious agencies. At any rate, the liquor seminis appears to be much more an accessory product of secre- tion in the glandular elements of the testicles than a necessary and essential constituent of the semen. A comparison with the liquor sanguinis would therefore not be applicable. We would rather draw attention to the fact that a peculiar fluid is also secreted in the female generative organs. For instance, among the mammalia the fluid contents in the Graafian follicles, which, taking it in all its bearings, we feel inclined to consider as ana- logous to the liquor seminis. The liquor seminis, wherever it occurs, exhibits itself as a homogeneous, transparent fluid, existing always only in a small quantity. It is frequently only observed after the ad- dition of a re-agent, as acetic acid and al- cohol, when it coagulates and forms a fine, delicate, granular matter betwixt the sper- matozoa. Formerly, one of the authors of this ar- ticle, R. Wagner , distinguished, in addition to the spermatozoa, other particular globular formations j-, which he called granula seminis, and which he considered at that time as in- dependent elements. At the present moment, however, it may be looked upon as decided that these formations occupy a relation of de- velopement ( genetisehen Beziehung) to the sper- matozoa j, being, in fact, the vesicular ele- * This modifies or changes the view respecting thefunctionof the liquor seminis, which was formerly entertained. See Rudolph Wagner’s Elements of Physiology ; translated by Robert Willis. Part I. p. 74. 3d German edition, S. 53. t Fragment* zur Physiologie der Zeugung, p. 29., in the Transactions of the Math. Physical Class of the Royal Bavarian Academy of Science, Mu- nich, 1837. Lehrbuch der Physiol. 3d edition, S. 13. English edition by Willis, p. 5. _ + Stein like-wise is at present of this opi- nion. (Vergleich. Anat. und Phys. der Insekt. S. 107.) after having previously represented these formations in the shape of a peculiar theory of procreation. ments which have since been generally acknow- ledged as the formative cells of the sperma- tozoa. The former opinion of R. Wagner, at a time when the formative processes of the spermatozoa was so little known, was appa- rently justified by the circumstance that these bodies are found not merely in the testicles, but likewise in the vasa deferentia. This fact is even at the present moment of great in- terest. It proves that the developing cells of the testicles are not all of them used for the production of the spermatozoa, but that a number of them are removed in their primitive state, such removal being either accidental, or caused by their incapability of a further developement. We need not enter here into other irregular and fluctuating constituents of the semen. They are principally found only in the duct of the generative organs, and generally consist of fatty globules, of several epithelial cells, &c., which, from their characteristic appearance, are readily perceived to be incidental ad- mixtures. Periodical developement of the spermatozoa and testicles. — The developement of the sper- matozoa in the interior of the testicles does not take place constantly and uniformly during the whole of life ; but a genuine semen, with its characteristic histological elements and physical peculiarities, is only secreted at the period of sexual maturity, and then only during the period of rutting. It is likewise only at this period that the semen is capable of acting with fructifying influence upon the female organs of reception. In those cases where the periods of rutting repeatedly occur in one year, where, as in human beings, and among most of the domestic animals, they are hardly separated by any perceptible or dis- tinct intervals, the spermatozoa are certainly found at all times from the period of puberty thoughout life. But even in these cases it may be assumed that the production of the spermatozoa is principally confined to the re- spective periods of rutting, although not per- haps entirely limited to it. The spermatozoa, like all other elementary constituents of the animal body, are likewise subjected to a process of re-formation (. Ruck - bUdungs-process), if they do not make their exit from the body. If the periods of rutting are separated from each other by longer in- tervals, this process affects likewise the organs for the transmission and for the preparation of the liquor seminis. The testicles and vasa deferentia in these cases decrease considerably in size and developement until the commence- ment of a new sexual period leads them to- wards a new state of turgescency, and anew capacitates them for the production of sper- matozoa. The period of rutting among most animals, at least in our climate, is associated with the commencement of the warmer season. The testicles then receive a larger influx of blood ; they increase in size ; the walls of the sper- matic canals become thicker, their lumina larger. These changes of the generative organs SEMEN. 474 may be most readily traced among birds, the increase of size of the testicles being very striking with them at the period of copula- tion, as proved by the researches of Hunter, as quoted by Owen*, to which we may add our own, which likewise have been instituted with the sparrow. During the winter the testicles only pos- sess a very small size. In a specimen which we examined in the middle of January, they scarcely measured a millimeter. Both tes- ticles were equally developed, had a globular shape, and weighed together (in a fresh state) about 3 milligrammes. The vasa deferentia, which we were only enabled to discover after a very accurate examination, appeared in the shape of a couple of thin and almost solid strings. Henceforward the testicles and sper- matic ducts begin to grow, although at first but very slowly. The 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 1^ 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-g-, the weight 6 Mgrs. By the end of the month the organ enlarges itself to a body of 2J Mm. in length, I§ Mm. in width, with a weight of 8 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 48 Mgrs., the length simul- taneously increasing to3.y Mm., the width to 2§. The subsequent developement 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 8 Mm., a width of almost 7 Mm. The weight, we 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 fo rmations. The testicles obtain their perfect 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 therefore by no means rare. Individual spe- cimens exhibit either a very premature or a very late developement. Thus we met with, for instance, as early as the middle of January, specimens, the testicles of which had a length of 2 Mm., a width of 1 J, and a weight of 6 Mgrs., such occurring usually only four weeks afterwards. Towards the end of the same month the testicles of another indi- vidual measured a length of 2i, 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 D Mm., a width of 1 Mm. Form and history of developement of 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 upon 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 abridged 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, i" 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 genera!. Let us now trace the different histological formations of the semen, according to form and connexion in the principal groups in the animal creation. Man. — In man (in which the sperma- tozoa (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 -Jf", at the outside J-J" ■ * We always refer in our measurements to Pari- sian lines : a millim. = 0.443 of a Paris line. Vol. I. p.354. art. Aves. SEMEN. 475 Of this by far the greatest part is occupied by the filiform tail. For the anterior body there hardly remains more than ^^-'"to The body is rather flattened on the sides, so as to represent the shape of an almond. Viewing it from the surface (fig. 323. a), it looks like an oval disc, the longitudinal dia- meter of which exceeds the greatest width by Fig. 323. Spermatozoa of Man. A, viewed 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 (fig. 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 T\'", in Mus musculus ff", in Hypudacus arvalis, Sciurus, Talpa fig'", in Plecotus auritus, Cercopithecus ruber -ffi1' . In many other cases, — in Canis, Felis, 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 ziro"'’ as a^so Tfdpm The size of the body in a rat amounts even to The difference, however, is frequently less considerable. In Canis, Rhinolophus, Hy- pudacus, Mus musculus, &c., the body only measures and even 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. Pliysiolog. 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 extremi- ties. In the Rhinolophus 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 mammalia 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 (fig. 324.). Here the body is very Fig. 324. Spermatozoa of the Squirrel (Sciurus 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 appeal', especially at the anterior end, much thickened. Another very remarkable form is seen in the body of the spermatozoa of the Muridas. It is attached to the anterior end of the caudal ap- pendix, like 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, whilst 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 SEMEN. 476 margin of the body which projects at the posterior part into an obtuse angle. In the rat (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 slightly de- veloped. The differences in the caudal appen- 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, which KolliJcer (who had like- wise observed this in the semen of rabbits) * Anna!, 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, certainly 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, however, 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. Kolliker 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 '» hut intermixed with them there are frequently found vesicles ol a smaller and of a larger diameter (to ')• 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 quality ; but this we cannot con- sider as its natural condition. Most of these vesicles are free within the little seminal canals (fig. 326. a, b, c). They are frequently surrounded by a cellular enclosure, * Tide Wagner, leones Physiolog. tab. 1. fig- 2- Elements of Physiology, p. 10 .fig. 4. SEMEN. 477 either singly {fig. 326. d) or in numbers of three four, six, or seven (fig- 326. e). A more con- Fig. 326. 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- lilcer’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 _j /// !_'// °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- bility of this opinion. It is certainly often difficult to determine whether an individual vesicle is destined for the production ot 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 ofdevelopement, 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 shadow it is seen lying in the in- terior {fig. 327. A, b) ; in addition to which it Fig. 327. A ’ B C I) 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 (fig. 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 Kolliker 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 ofdevelopement, 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 causedby 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-like 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-like portion. The body, in most birds prolonged into a cylinder, is distin- Spermatozna of the Cock (Gallus domesticus). guished by a greater thickness from the thin and filiform tail, which is twice its length {fig- 328.). In other instances, how- Fig. 329. ever, it makes a number of spiral twists, generally four, which make it look like 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 {fig- 329.). The latter form is generally peculiar to the singing birds, and, indeed, an ex- elusive 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 singing 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 thrushes, 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 b), in the Lanins (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 tremity of the spermatozoon. The s'lmus" ar)d thickness of the tail, like the number and arrangement I \ ( of the windings, is subject to many changes and fluctuations among the several genera. It is particularly strong and rigid among the Fringillidae, 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 = F. Canaria , F. domestica so"') . The tail part of the spermatozoa of the Lanidrn is, on the other hand, very short and fine, its length scarcely measures -ffi" — °f which about -oho'" — tooW goes to the anterior spiral body. The spermatozoa of Oriolus are only slightly larger. Among the Thrushes the length is about , 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, Artbus, Certhia, &c. Motacilla and Emberza have spermatozoa of so'", Sylvia (Phoenicurus vibilatrix) and Saxicola of ffi". 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 Lanidae. In other words, the formations just alluded 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 -xW" — -fits'" (Picus, Falco, Columba, Gallus, Pavo, Anas, &c.), but seldom less (in Vanellus and Cuculus = sho'")- 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 lines, 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 easy 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 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 its exit with the tail end first (Jig- 330.). Fig. 330. Spermatozoa of the Cock partly enclosed by 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- malia; these generally have a diameter of r&s"' — Jo"' — so'"- 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 (Jig. 33].). On the destruction Fig. 331. A Mother Cell from the Cock, 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 (Jig. 332.), where they lie together often in a great number, but never * Lekrbucli der Fhysiol. 3d edit. § 18. S. 27. in regular fascicular groups. Finally, this cyst also gets dissolved, without, however, Fig. 332. A Mother 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 (fig. 333.). Fig. 333. Cyst 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 likewise 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 (fig. 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 Muller’s Ar- chiv. 1836, S. 225., in Fragm. zur Physiol, der Zeugung ; in Lehrbuch der Physiolog. § 17. S. 25. ; as also in the Icon. Phys. tab. I. fig. 5. (copied in the article, Entozoa, Yol. II. p. 112.), which 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 free, 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 cysts, 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 Fig. 335. Mother Cell with a Bundle of Spermatozoa from Fringilla 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 Fringilla ccelebs. tails of the spermatozoa are shorter than among the Lanidte. The cysts here retain almost entirely their original form, or do not enlarge to any extent (Jig. 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. 48 i 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 lengthwise, 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 encourage the conjecture just now alluded to (Jig. 340.); Fig. 340. Part of Spermatozoon of Triton. a, body of the spermatozoon ; b, spiral windings of the delicate tail. Spermatozoa of Lacerta Spermatozoon of Itana • agilis. temporaria. spermatozoa measure about Jj", the length of the body amounts to only stto"' > *n t'le lizards (Lacerta), on the other hand, in which the spermatozoa are smaller (fj" — Jj") about nis"'- The differences of the form of the sperma- tozoa are however much greater in the group of the Batrachia, which likewise distinguish them- selves in other respects by various deviating circumstances. A staff-like 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 — Jj", of which the body occupies more than the anterior third. Among the Salamanders the body is likewise cylindrical, but much longer (Jj''), 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-like * Vide copies in R. Wagner; Fragment. Tab. II. f Froriep’s Neuen Notizen, vol. ii. S. 281. No. xl. VOL. IV. but in other cases the twistings 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 twistings. 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 Pouchet’s 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 fj", in 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 Bombinator igneus. The spermatozoa in Bombinator 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. 35G. i i 482 SEMEN. tened. The posterior end is continued into the the cell of developement continue for a long tail, which latter is tolerably thick, and almost time adhering to the body of the spermatozoa, straight at its commencement. It gradually, generally in the centre, exhibiting the appear- however, assumes a very thin appearance, ance of a comb-like appendix of a variable becoming a very attenuated hair-like ap- shape and size. pendix, which exhibits the same spiral wind- The formation of the spermatozoa in the ings that occur among the Salamanders. The interior of independent cells of developement length of the spermatozoa, as far down as likewise takes place in a similar manner in where the tail bends itself, amounts to -gfi" — the Lacerta crocea. We have but rarely seen -ij-'". that the same cells are enveloped by larger Another very singular form of spermatozoa cysts at the period of the production of the is met with in Pelobates fuscus. Thesperma- spermatozoa, which is commonly the casein tozoa measure J5///. There is no boundary former stages of the developement. The num- perceptible between the body and tail part, berof cells contained in one common cyst is but one half of the spermatozoon distinguishes generally only very small, seldom exceeding itself from the other by a considerable thick- eight. The same is found, according to the ness. Both, however, gradually pass into one another. The thicker part exhibits from its Fig. 343. commencement a number (generally eight) of spiral windings, which increase in size towards the anterior free end (y?g.342.). The anterior Fig. 342. Spermatozoa of Pelobates fuscus. Cells of developemen t of Testudo grceca with Sperma- tozoa and external cysts. ( After Kolliker.') observations of Kolliker, in Testudo graeca ; but the external cyst in this instance is said generally to persist for a longer period. The 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 {fig. 344.). It is only afterwards, Fig. 344. end itself does not however participate in this formation. It is of a more delicate quality, 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 Reptilia 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 their production in the interior of se- parate solitary cells of developement ; as, for instance, in Anguis fragilis, or Bombinator igneus. 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 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 ..t 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 body does so (fig. 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. It is a remarkable sight to see the cyst burst- Fig. 345. A bundle of Spermatozoa of Pelobates. 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 — -g-ho'", or even smaller, down to to*oo,/ /> as 'n Perea fluviatilis), and an extraordinarily thin, hair- Spermatozoa of Perea Spermatozoa of Cobitis fluviatilis. 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 (fig. 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« .348 Pefomyzon, in which the form of ° ’ the body is, however, different. In P. marinus* the body is egg-shaped; j in P. fluviatilis (fig. 348.) staff- shaped. The length of the body in P. fluviatilis is T|/'. The spermatozoa among the Pla- giostome fishes are similarl}' formed Spermato- to those of the birds. They are long, zoon of filiform, and furnished with an an- Petromy- terjor cylindrical body. In Scy Ilium tilis. la~ Canicula the body is stiff and quite straight, and tapers at both ends. The tail is thin, and of an equal length to the b°Jy GV"). * J. Muller, Untersuch. uber zu Eingewerde der Eische, Berl. 1845, S. 6. The spermatozoa of Scymnus niceaensis ( fig. 349. a) are similar but rather longer, whilst Fig. 349. A. Spermatozoa of B. Spermatozoon of Scymnus nicecensis. Torpedo jVarce. 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 whilst the length of the whole spermatozoon amounts to ffi" 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. 349. b), Raja rubus, &c. In Raja oxyrhynchus it is only the anterior part of the body which is spirally wound in a length of about fj", 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 spermatozoon amounts to Chimera monstrosa like- wise exhibits these windings, notwithstanding the comparatively short body of its spermatozoa, which have a length of ffi" ■ The number of windings 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 Hallmann* 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. Cysts, 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 * Muller’s Archiv., 1840, S. 467. 484 SEMEN. enclosed by a lesser or greater number of cyst-like mother cells {Jig. 350.). The size of each of these cysts amounts to about j&o'", wherever the number of the enclosed cells is small ; but in the reverse case it may in- crease to Js'". 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. 35 1 . Spermatozoa in the interior of the cysts {Totpedo 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. 353.); but here, as well as in the Lacerta, &c., the formation of the spermatozoa only takes place Fig. 353. Spermatic cells from Cyprinus brama. 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 Kollilcer that the spermatozoa of Am- phioxus develope themselves from little cells (of ToVoW — tIo"')- which 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 spindle-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. Moi.lusca. — 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 Fig. 354. Cephalopoda. — In 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 {Jig. 354.), which have a length of P", of which xkrs" belongs to the anterior body. The spermatozoain Sepiola are shorter, and furnished with a body which measures The developement of these spermatozoa occurs just as in birds, according to lldlliker. 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, Spermatozoon of Octopus vulgaris. i A 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 des Sciences Nat. 1842, tome xvii p. 335. Patella (Jig. 355.). The spermatozoa of the former consist of thin delicate fibres of fj", the anterior body of which has an oblong shape, measuring about ■ The body in Chi- ton is broader, almost pear-shaped, and of a more considerable size (J--"). Similar cer- caria-like spermatozoa are possessed by Ha- lyotis and Bermetus, as also by Trochus 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, Pomato- branchiata, and Pteropods. 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 spiral windings are closer, as among the singing birds, and confined to the anterior body only (Jig. 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 — Jj" , in Thedys, Aplysia Jj", in Pleurobranchia Meckelii even x"' &c The spermatozoa of pulmonary Gasteropods are usually still larger, extending to V", as in Helix. As in the Nudibranchiata, thev 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 with an appendix, which must be viewed as a peculiar form of body (Jig. 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. Clausilia, &c.), it exhibits two easy spiral windings, almost in the form of an S. Some Fig. 357. 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 by Kolli/cer’s excellent researches. Even in the Gasteropods we may observe the deve- lopement of the spermatozoa in the interior of particular vesicles. The arrangement of these parts only exhibits some deviation. In Helix or Clausilia, in which 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 (fig. 358.), which is in diameter -.2—"' to f-f". 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- quently in an irregular manner, generally measure but are sometimes larger, to the extent of T&o/// and above it. In the interior of these cells we meet again with vesicular formations, generally mea- suring njja"'. 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 (fig. 359.). According to the Fig. 359. Spermatozoon of Helix pomatia in the interior of its developing cell. (After Kolliker.') observations of K'dllilcer, 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 spermatozoa being sufficiently developed, the vesicle of developement is dissolved, and the spermatozoa get into the cavity of the exter- nal cell (fig. 360.). Here they may usually Fig. 300. Spermatozoa of Helix pomatia in the interior 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 lengthwise, 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 (fig, 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 attachment 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.). Spermatozoa of Helix po- A group of Spermatozoa matia at their extrusion of Helix pomatia , from the mother cell. partially 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 cysts 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 this, confirming, at the same time, the conjecture of Kolliker ; 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 globular remainder of the cellular contents (Jig. 363.). Fig. 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, Lymnaeus, &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 Cyclobranehiata, in Turbo, Buccinum, &c.) ; but this does not change in any way the developement and mode of grouping together of the spermatozoa. 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 vesi- cles in the shape of a round mass. Acepliala. — In comparison with the variety in the form of the spermatozoa among the Gasteropods, we meet with but slight differ- ences in the class of the Acephala, at least among the Lamellibranchiates.* The sperma- tozoa of these Mollusca consist of delicate fibres of about in length, the anterior end of which supports a short and distinct body of variable size (from — Zoo'") (fig- 364.). This body is usually (as in Unio, Cyclas, Clavagella) cylindrical ; in other cases (for instance in Mytilus, Pholas) pear-shaped. Respecting the formation of these fibres we only know Kol- liker’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- stance, in Chiton, &c. : our ex- amination of Unio was not calculated to give us an insight into it. Fig. 364. 13 Spermatozoon of Unio. * VideV. Siebold in Muller’s Archiv. 1837, S. 381. i i 4 4-88 SEMEN. Tunicata. — Among the Tunicata the Ascidia possess spermatozoa quite similar to those of the Lamellibranchi- 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 {fig- 365.) ; the head is usually — go"' , the tail fluctu- ating between gfi" — gt"' The sper- matozoa seem to want a body in the Salpae, according to the observations of Spermatozoon of PliaUuria Ko Hiker, monacha. ( After Kolliker .) The endogenous formation of the spermatozoa in the Ascidia is as little distinct asamong the Lamellibranchiata. Itseems,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. Akticulata. — In thesecond great division of the Invertebrate animals, among the Artkro- poda, the filiform shape of the spermatozoa, if indeed it occurs at all, is generally still more marked in its developement 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 uniformity. They ap- pear, without exception, as filiform fibres {fig. 366.), which are frequently distinguished by being extremely slender in proportion to their length (the latter exceeds in Staphylinus, but is generally less ; in Culex gg"; in Agrion Virgo gg" — go'"). 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 body, this appendix being formed of two short crura, which converge Fig. 365. and pass into one towards the anterior part, like the head of an arrow. Fig. 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, (they are smaller in many Diptera, Culex (•g-£o///), Musca, Fig. 367. Cysts, with developing vesicles, from the testicle oj Staphylinus cyaneus. &c.), are in a variable, generally, however, in considerable number (twenty, thirty, forty), enveloped by larger cysts {fig. 367.) These cysts or enveloping cells frequently attain the size of gg" (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 which case the vesicles of developement form much smaller than in the lower part. It fol- loose groups, as in Amphioxus. 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 i /// i /// Too 75 • 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. Siebold * 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 the 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 * Ubcr die Spermatozoiden der Locustinen, A. I a. o. S. 1. 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 — Coleoptera, 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. cyaneus. (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. Siebold 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 {fig. 371. b) these bundles are wrapped 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 {c. g. in Scatopsis). In their gradual advance through the vas deferens, the spermatozoa lose this mode of grouping; — their bundles separate. In the place of this they are, however, very fre- quently enclosed in masses by peculiar baglike enclosures, the so-called Spermatophora *, 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 Locustinas 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, Tittigoria, &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- markable shape, velopement alone ments alluded to perhaps suppose. traction, or w hether 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- The history of their de- can prove that the ele- are not, as one might 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 spermatozoa. 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 Ay/// long, and rather thickened at one end. They develope themselves, according to Kdlliker, in the usual manner in the interior of vesicles, which are contained, in numbers, in a larger cyst-like cell. In the Aranete, on the other hand, which, owing to the difficulty of an anatomical ex- amination, have hitherto but rarely been a careful inspection, the sper- said to present a very dif- V. Sit bold*, to whom we are the only statements regarding as round or reni- the interior wall of submitted to matozoa are ferent shape, indebted for them, describes them form cellular bodies, 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 of\iTy//'', in which a very perceptible nu- cleus is contained. The nucleus is at first round {fig. 372. a), but gradually elongates * Vid. Stein. * Lehrbuch der Vergluchenden Anatomie, § 544. SEMEN. 491 itself, and then becomes a short, and gene- rally curved, cylinder (b), one end of which Fig. 37 2. Seminal cells in the testicles of CluUona daustraria. 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 maigin oi 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 not been able to discover further stages of develope- Fig. 373. ment in the interior of the \ testicles ; but we have suc- |\ ceeded in detecting, besides i the already mentioned cor- I j puscles, a number of dis- ij tinct linear fibres of — 7 fJ" ( fig. 373.) in the spoon- I 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, j and thicker than the pos- I terior tail-like part. Very i similar, only rather longer, Seminal fibres of seminal fibres are likewise CluUona. 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 them cells of developement, formations which, besides the spermatozoa, also occur in the capsules ot 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 cannot 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. Siebold’s 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 (Jig. 374, a) the Fig. 374. Developement of the spermatic cells of Epeira. nucleus which they contain . The cells are enclosed in larger cysts (ofT5L_,// — %-") ; 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 any where penetrate beyond the cell. It constantly 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 ihs")’ It usually exhibits here some slight and irregular windings, which 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 happens 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 formerly contained in 492 SEMEN. it. A tail part we have, however, never been able to discover in the spermatozoa of Epeira. The form was uniformly cylindrical, 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 sbo'"- Mg. 375. 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 (u, 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 ^bo'"; they, 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 A carina;, we have as yet had but few observations ; it appears, however, from the statements oi V. Siebold, that similar stages of develope- ment take place as among the genuine Aranece. V. Siebold observed in the testicles of Ixodes ricinus a large number of rather long and large rods, which had an arched curvature, and were enlarged at one end in a clubbed shape. These rods were probably the developed spermatozoa, and of a similar na- ture to those we have found in Epeira. We do not venture to determine whether the same inference may be drawn with regard to the club- shaped corpuscles, which V. Siebold discovered in the Hydrachneae and Gamaseas. From the description given, however, viz. of these cor- puscles enclosing an oblong spot in the en- larged end, and of their having been pro- duced by the metamorphosis of round nu- cleated cells, we would rather suppose that they were mere stages of developement of the seminal cells, similar, perhaps, to the pe- dunculated seminal corpuscles in Clubiona. In addition to this we may mention that Dr. Frey has communicated to us an observation, from which it appears that Hydrachna like- wise possesses spermatozoa of a filiform shape. The contents of the testicles in other Acarinae (Trombidium, Zetea, Oribatea, Hop- lophora, &c.), consist of small globules, which in Bdeila assume a cylindrical shape. We are inclined to consider such as the free nuclei of seminal cells. We, at least, believe we have seen in Phalangium that they were surrounded by a cellular vesicle. Myriapoda. — The remarkable spermatozoa of the Ckilopoda, which appear either as cylin- drical corpuscles when in a developed state (in Glomeris), or (as in lulus) as short conical formations with a rounded point, are, accord- ing to our observations, of the same nature as the foregoing. In lulus terrestris, in which we have traced the developement of these parts through all phases, the primitive contents of the testicles consist of a great number of small round cells of , containing a very clear nucleus (of about which lies close to the cell wall, and is highly refracting {Jig. 376. a). In the course of the developement, the nucleus en- Fig. 376. Spermatic cells of lulus terrestris. larges, and, in so doing, gradually converts itself into a short cone (b, c, d), which, with its point, extends beyond the surface of the cell. For a time the cell continues to be at- tached to the surface, until it dissolves, rendering the seminal corpuscles free {Jig. 377.). The basal part of the developed Fig. 377. Spermatozoa of lulus terrestris. spermatozoa has a diameter of ^ho'" — jbx < and is rather protuberant and enlarged at the edges. The height of the spermatozoa is always less than the width, generally by one half. On comparing the phenomenon in the form- ation of these bodies with the first changes of the nucleus in Clubiona, the analogy between the two will clearly be seen. The relative value only of the two is changed. The corresponding conditions in Clubiona form mere stages of transition necessary for fur- ther developement, whilst the developement in lulus does not proceed further than the stage described. SEMEN. 493 The differences in the form and develope- ment of the spermatozoa of lulus fabu- losus are very interesting. The formation of these parts does not confine itself, as in lulus terrestris, to the mere metamorphosis of the nucleus into spermatozoa. Previ- ous to the latter projecting over the ex- ternal surface, the cell membrane gets en- larged on the opposite side {Jig. 378. a, b, c) into a corpuscle, which assumes the Fig. 378. Spermatic cells of lulus fabulosus. same shape as the nucleus. The sperma- tozoa in I. fabulosus do not, therefore, con- sist in one short cone, but rather in two such formations {Jig. 378. d,e, f), which are turned towards each other with their broad surfaces partially touching. One of these is not unfrcquently distinguished from the other by a more considerable size. In a developed state, when the original cell membrane, in which the cone was formerly imbedded, has disappeared, the two parts sometimes separate, each having a perfect resemblance to the spermatozoa of I. terrestris. V. Siebold, to whom we are indebted for the first accurate statement respecting the Chilo- pods*, was not acquainted with the developed forms of these parts in I. fabulosus. He de- scribes as such the stages of developement of the spermatic cells illustrated by us in y?g. 378. A to e, comparing them with the shape of snuff-boxes, in which the lower surface is much thickened, whilst the upper surface contains in the centre a roundish nucleus. The spermatozoa of the Chilognatka f are filiform and of a very considerable length and thickness ; e. g. in Geophilus, where they mea- sure IF". Towards one end they gradually become finer, and usually rather undulating or spiral, particularly at the anterior thick part. In Geophilus these fibres are rolled up separately into one ring-like curl ; in Scolopendra, on the other hand, they are straight, and united in small numbers into string-like bundles. Nothing certain is as yet known respecting the developement of these fibres ; but, with V. Siebold, we think it very probable that they originate from the larger cells (measuring in Geophilus fj", in Lithobius — Jj"), which con- tain a single, double, or treble nucleus (of ihJ" — Jo ") with a nucleolus, and * Muller’s Archiv. 1841, S. 13. f See Stein. Muller’s Archiv. 1842, S. 258. which are found in great quantity in the testicles. From analogy we may infer that it is in the nucleus within the vesicle that the fibres are produced. The association of the groups of spermatozoa in fascicles in Li- thobius has, however, no intimate connection with the manner of their production, because the enclosed nuclei never equal in number the united fibres enclosed in one bundle. It is probably the result of a subsequent transition (like the formation of the seminal fibrous strings in the Hexapods). Crustacea. — Among the Crustacea, to which we now proceed, we likewise meet with, as in the Myriapoda and Arachnida, many vary- ing forms of the seminal elements. The most remarkable are the so-called radiating cells of the Decapods*, small, strangely formed corpuscles of a variable shape (and generally of a size of which owe their origin to a metamorphosis of sper- matic cells containing nuclei. By the dif- ferent developement of the nucleus and cell membrane {Jig. 379. a, b, c, d), they are F/g. 379. Radiating cells of Grapsus marmoratus (a), Pa- gurus oculatus (b, c), and Pisa tetraodon (d). (. After Kolliker .) usually divided into two portions of different shape and size, and are furnished at the bound- ary between the two with delicate and fibrous rays, which vary in number from one to four, but are generally three ; but this is effected in such a manner that the rays constantly re- main connected with the division produced from the metamorphosis of the original cell membrane, and never with the nucleus part. These radiating cells are produced from the original simple seminal cells in the fol- lowing manner : — The nucleus (as in Clu- biona and the Iulides) gradually projects further and further towards the outside, thereby metamorphosing itself into a roundish (in Calappa, Hyas, Stenorhynchus, Scyllarus, Astacus fluviatilis, &c.) or spiral (in Cran- gon, Pisa, Galathea, Pagurus) appendix of the cell wall, which frequently enlarges itself considerably, especially in Pagurus, where it reaches Jj" . In the mean time, the cell membrane has likewise undergone some changes. It either gets flattened more or less (Palaemon, Stenorhynchus, Pica, Calappa), or it lengthens itself into a cylindrical cor- puscle (Galathea, Astacus marinus). It is sometimes the case, however, that it retains its original round form (Ilia, Pilumnus, Pagurus, Astacus fluviatilis). At the anterior end of this last corpuscle, where the part containing the nucleus ad- heres to it, the rays now gradually dart forth, * Tide the numerous and accurate statements and illustrations of Kolliker. 491 at regular intervals, which give to the corpus- cle sometimes an angular appearance, as in Pisa. The length of the rays holds an in- verse ratio to the size of the cells, and is, in most cases, either equal to, or double, their diameter. The peculiar form of these seminal ele- ments naturally provokes the question, whe- ther they really represent the developed spermatozoa, or whether they are not per- haps mere phases of developement. The relation in which they stand to the simple spermatic cells suggests a conjecture of this kind ; and the more so as the rays at- tached to them already present the greatest similarity with the usual filiform sperma- tozoa. We regret to say, that we are not yet in a position to decide this question with perfect certainty. From various obser- vations, however, the latter assumption gains in probability. Kollilcer has observed (in Calappa) that the adhering nucleus is lost at a later period ; further, that in Portunus corru- gatus, the cell membrane gradually gets very much contracted ; whilst, on the other hand, the rays considerably lengthen themselves. If we consider, in addition to this, that radiated cells are found in Ilia Nucleus, which C/fg.380.) Fig. 380. SEMEN. us, owing to the remarkable mode of form- ation of the spermatozoa, which is extremely similar to the developement of the radiating cells in the other Decapods. The primitive seminal cells in Mysis appear as round pale nucleated vesicles of about in diameter {Jig. 381.). In the course oftheir Fig. 381. A cell with rays Jrom Ilia Nucleus. ( After Kolliker.') possess extraordinarily long fibres on a very small body ; that finally in Pagurus, as it seems, the rays perfectly sever themselves from the corpuscles ; that, at all events, developed radiating cells, without rays, are often found in the latter, it must induce us to share Kolliker's opinion, that the ra- diating cells, at this stage of their formation, are not yet perfected ; but that they are more likely to be instrumental in the developement of ordinary spermatozoa. Such spermatozoa, however (if we except the genus Mysis, which is certainly unjustly divided from the Decapoda), have not yet been proved to exist in any of the animals belonging to this class. Kollilcer has succeeded only in Dronia Kumphii in discovering a great number of fine pale fibres of Tr5',/ in the lowest part of the vas deferens, which probably owe their origin to the rays of the seminal corpuscles, which, however, are much shorter than those fibres, hardly measuring above xjoo'"- Such a negative result can, however, the less determine our judgment on the nature of the radiating cells, since the observations, which one of us ( R . Leuckart , together with Dr. Fret/) has instituted, with regard to the deve- lopement of the spermatozoa in Mysis, have brought the question pretty nearly to a deci- sion. V. Siebo/d was already acquainted with the filiform spermatozoa in this crawfish, which are distinguished by their great length (of i'"). This animal possesses the more interest for Developement of the seminal corpuscles in Mysis. { After Frey and Leuckart.') further developement, a small wart-like pro- cess (b) rises somewhere on this vesicle, which gradually lengthens itself (c, d), and grows into a long cylindrical tube of Jj". The nucleus does not participate, in any way, in this metamorphosis. It retains its original form, and remains at its original place in the interior of the seminal cell, which is seated on the cylindrical staff like a globular appendix. In spite of their rather peculiar shape, we do not hesitate to pronounce these seminal elements of Mysis as parallels of the radiating cells of the other Decapods. Excepting the rays, we can find no material difference between them. That the wall of the cell is not immedi- ately metamorphosed into the cylindrical body, is equally as little material as the circumstance that the nucleus remains without change, and does not project outwards. Indeed, we also find the same relation in the radiating cells of Astacus marinus {Jig. 382.), where the nu- cleus likewise remains in the interior of the cylindrical radiated corpuscle. To judge from their form, these seminal cor- puscles would have most resemblance to the radiated cells of Pagurus ; but, according to Kolliker’s observations, it would appear that the long cylindrical appendix has originated Fig. 382. Radiating cells of Astacus marinus {After Kolliker. ) from the metamorphosis of the cellular nucleus. The nucleus in Mysis, together with the sorrounding head-shaped part of the seminal corpuscle, is subsequently destroyed, the same as Kolliker has found it in Calappa. There merely remains, then, a simple long cylinder {Jig. 383. a), which represents the radiating corpuscle. The formation of the spermatozoa takes place in the interior of this cylinder : they consist of long linear fibres, which lie in 495 SEMEN. it lengthwise, until they perforate the exter- nal enclosure at one end, and now gradu- Fig. 383. Developement of the Spermatozoa in Mysis. (After Frey and Leuckart .) ally project outwards (b, c). The number of the fibres thus formed is generally limited 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 Kblliker, 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- l'.ke mass. The spermatozoa in the other orders of the Malacostraca , the Amphipoda, and Isopoda, are uniformly filiform. Their developement takes place in the usual way, without 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 in Gammarus Pulex 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. Kollilcer 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 believe, however, that such an Fig. 384. Spermatozoa of Gammarus Pulex. appendix ( fig . 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 Kblliker, 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 Kblliker describes in Hj^peria, 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 Oniscidee, according to our observation, also takes place in the interior of transparent cells*, which reach 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 ■&/", 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 J5") which possess, besides nucleus and nucleolus, dark gra- nular contents, and which form the epithelium of the vas deferens, hut which are wanting in the genuine seminal tubes, should not be confounded with these seminal cells. Similar cells, only smaller (of about are likewise 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 Kblliker, mea- sure upon an average about -go'" in Pychno- gonum Balaenarum. Equally filiform and also pointed at both ends, are the developed spermatozoa of the Fig. 385. Developement of the Spermatozoa in Clithamalus Philippii. (After Kolliker.) Cirripeds, the size of which, in Chthamalus Philippii, amounts to about J-J" . They are produced from smaller nucleated cells (of ,J>7T/// — _j_,//V which would seem, from ex- ternal appearances, simply to grow out into seminal fibres {Jig. 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 most 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 l"'), 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 f, 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 with the spermatozoa in the same individual ; and therefore to the her- maphrodite condition of the genitals in Cypris. f Vergleich: Anat. S. 483. j According to Scholler, hi 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 lulus. They at first appear as roundish nuclei in the in- terior of thq seminal cells, which have a size of zio"' — 2oo'///- At this period the nuclei measure -gfo'" ; they subsequently grow, change their shape to an oval, and in so doing not un frequently 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 1'"), 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 Ilirudo fj", Planaria varicosa -Jj", in 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 bran chiated Annelida, Fig. 386. I B Spermatozoa of Lumbricus (a) ; of Nemertis Ehren- bergii (b) ; and Planaria verrucata (c). (After Kolliker.') 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 * Frey and Leuckart in Wagner’s Zootomie, 2d edit. Part II. p. 259. f Will in Wiegman’s Archiv., 1844, Tk. I. S. 340. | 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 eases produced separately from small cells, containing nuclei (generally of -g-fa'" — sho'"), which lie together in round masses ; being generally situated on the circumference of a large central ball among the bristled wo rips and Hirudines, as among Fig. 387. A \ Developernent of the spermatozoa in Lumbricus, the Helicinse (fig. 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 of Kolliker j~ on the developernent 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- lopernent 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 ot cells originate through the continued en- * Wagner in Muller’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 developernent lead to the form of groups of cells, taking their origin from one single nucleated cell containing some brownish granules. In the 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 Helicinm. In other cases the mother cell not only survives the endogenous formation of daughter cells, but also the process of the developernent 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 Fig. 389. Developernent of the spermatozoa of Flnstra carnosa. ( After Kolliker.') most correctly classed among the Annelida), for instance, in Laguncula and Alcyonella*, * Vid. Yon Beneden in the Mem. de l’Acad. de Bruxelles, tom. xv. and xviii. It 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 (T£Tr/// — f^,r) cyst-like mother cell ( fig . 388. a.). The spermatozoa even here, how- ever, are produced by the apparent growing out of the small cells of developement (of ■sfa'") containing nuclei (see fig. 389.). When developed they are linear and proportion- ately thick and long (in Flustra about and frequently, it seems, furnished with a roundish or oval corpuscle. Rotifera — The spermatozoa of the Rotifera, at least of Megalotrocha, have a similar pin- like form, if we may judge from the observa- tion of Kollilcer*, which 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 they have been confounded with the remarkable vibratile organs, which are certainly not spermatozoa. Kollilcer' 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. Spcrmatophora 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 shfi", and a short rigid peduncle, which projects more or less outwards, and has a varying thickness {fig. 390.). The spermatozoa in Fig. 390. Spermatozoa of Strongylus auricularis. ( After Reichert in Muller'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, having sought in vain, and for a long time, for other forms of developement, and having found * Froriep’s Neuen Notizen, S. 596. the very same formations again, in a perfectly unchanged shape, in the female individuals. We must therefore characterise Kolliker’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 nuclei, which, according to Reichert's researches, are produced in the interior of large mother cells * {fig. 391.). The nucleus Fig. 391. Spermatic cell of Ascaris acuminata, with four vesicles of developement. {After Reichert.) has at first a roundish shape {fig. 392.), but gradually stretches itself more and more, and i 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 which does not in- variably occur, is the only distinction that can be found between the Nematoda and the Iulidse. Radiata. — Echinodcrmata. — The sper- matozoa, in the division of the Echi- nodermata, possess, it seems throughout, a pin-like form {fig. .393.), with a small Fig. 393. Spermatozoon of Ilolothuria tuhulosa. roundish body (of eio'")> and a vel7 slender tail appendix of about ff" — . 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 * Muller’s Archiv. 1847, S. 88. 499 SEMEN. seems rather to indicate a gradual elonga- tion of the cells. The spermatozoa lie to- gether in bundles, either enclosed by the cysts or free. Acalephce and Anthozoa. — The Acalephaeand Anthozoa exhibit quite a similar series ofphe- nomena. The bodies of the spermatozoa are usually round, frequently however, especially among the Medusa? {fig. 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 period 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 Medusas, 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. Ehrenberg, 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. General 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. Kolliker * was the first who directed attention to the wide exten- sion of this mode of production f, hav- * Die Bildung der Samenfaden. t The doubts which Reichert 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 metamorphosis of the vesicles of developement into seminal fibres (by means of elongation, growing out, &c.). The laws of analogy certainly justify us in drawing the same inference as Kolliker ; 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 type. 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 Kb'lli/cer 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; butwedare notconceal 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 rations 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 clue 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 form- 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 prises, 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 tubuii seminiferi. Nevertheless, some observations that have been made may perhaps already 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 Mechel * and h 61- liher 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 Archiv. 1844. ■01 SEMEN. 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 3-^ 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 all 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 Chilopoda, Acarina, Entomostraca, and Nematoda furnish us with sufficient proofs of this, — proofs which contradict the as- sumption of IC6 Hiker 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 are 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 have 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 in 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 only 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 rela- 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 cannot agree to the objection that 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, which 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- flect 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 formation 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 it 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).-)- 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. Kotliker'sX observa- tions, as well as our own more recent ones, instituted upon 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 the 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 a 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 celi 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 Planar im 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 the discovery of Frey and Leuc- kart (Wagner’s Zootomie, ii. p. 61.), which sub- sequently, has also been made by H. Meckel (Mtil- .ler’s Arcliiv. 1846, S. 26.). t Vid. Henle (Allgemein. Anat. S. 193.) and Zwicky (Metamorphose der Thrombus). J R. Wagner in Weigmann’s Arcliiv. 1*835. rally ; and it was frequently asserted that the distinct traces of an internal organization had been found in them. Even Leuwenhoelc *, 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 Ehrenbergf 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 cl animal organizations, is a very unsafe ar.d 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 Infusoriensthierchen, S. 465. t Nov. Act. Acad. Leopold, vol. xix. p. 239. § For instance, Nordmann , has described the severed ciliated cells from the sails of the larvae of Nudibrancliiata as parasitic Infusoria (Cos- mella hydrarhaoides). (Versuch einer Mono- graphic der Tergipes Edwardsii. Petersburg!!. 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.')' Such spores as these may be found described and illustrated in the well-known magnificent work of 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 are capable of independent motions, and even not every one of these. No such movements have as yet been perceived in the spermatozoa of the Malacostraea (Isopoda and Amphipoda). They appear motionless and rigid. The same hoids 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 fungi. * Yid. Unger, Die Planze im Moment der Thier- wendung; also Yon Siebold, Dissert.de Finibus inter Regnum Animaie et Yegetabile constitnendis. t Fresenius, Zur Controverse liber die Verwand- 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 difficulty 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 spermatozoa 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 fili- 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 lie 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 SEMEN. 504 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-like spermatozoa of the Insects, Gas- teropoda, Helmintha, and Cirripeda, and also sometimes, although in a slighter degree, in those of the Reptiliaand Mammalia. Hiebold* was the first who estimated these latter phe- nomena at their proper value, attributing to them their real cause, viz. the hygroscopic quality of the spermatozoa. These phenomena take place only on the addition of fresh water, whilst sea water exercises but little influence on the sper- matozoa, which may be 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- dium 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 at 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 * Muller’s Archiv. 1836, S. 19. peculiarly beautiful sight is afforded by the aggregate motion of the spermatozoa in the semen of the earth worm, which 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 winding motions of the sperma- tozoa, which follow each other in quick and regular succession, imparting the impulse to the whole mass. Motion, however, is entirely wanting when (as is especially the case among the insects) the spermatozoa are united into simple arid 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 with 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 its 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 motion 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 different influence on the spermatozoa of the coki- biooded animals; among the fishes, for in- stance, they continue moving for days 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 whe- 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. 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 likewise 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 Limnaeus 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 oil the movements of the spermatozoa, vid. Donne’s Nouvelles Experiences sur les Ani- malcules Spermat., Paris, 1837 ; as well as Krse- mer, p. 17. In some cases, however, our own re- searches have furnished a different result. 505 Fourcroy, Vauquelin , Jordan, John, and Las - 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 Las saigne. Spermatine, however, the more intimate knowledge of which would have possessed the principal 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 fluid 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- lowish, 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 quantities of phos- phates and sulphates of the alkalies. The spermatic fluid therefore resembles a thin solution of mucus. The spermatozoa which were left after 506 SEMEN. filtration were carefully Washed with water : they were thus quite pure, excepting the ad- mixture of some few epithelial 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 alkaline 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 (4'05 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, lime was recognised, amounted to 5'21 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. Nitric 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 white 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 pieces, and the milky semen expressed. It consisted of spermatozoa and numerous epi- thelial cells. The reaction in the testicles was neutral, in the epididymis 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 of 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. The pure semen presents the appearance of a milky fluid, of a mucous consistence, and neutral reaction. A slight alkaline 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 5 per cent, of phosphate of lime. 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 alkalies. 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 perfectly 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 aomposition, 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 by 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.f *■ Versuch einer Allgem. Pliysiolog. Chetnie. § 532. 560. f In spite of this functional difference we cannot help regarding spermatozoa and ova as constituents of the animal organization. Reichert, who declares them to be organizations of quite a peculiar kind, 507 SEMEN. 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. Physiological 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 operandi in the process of fecundation. Indeed, it would almost seem that an answer to such an inquiry is farther of}' 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 spermatine 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 LeuwenhoeJc, Andry , 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 doctrine of an Aura seminalis 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- which, in a certain degree, form a medium between animals and elementary parts of animals, seems en- tirely to forget that it is only the morphological 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 proof of the great organizability of the semen, of the ready mode of dispersing it, which such an operation upon the ovum would a priori 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 liquor 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, without a similar physiological importance. The following fact, however, appears to us of more real importance, viz. that a liquor se- minis is positively not at all traceable in many’, 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 from the male animals, and then left 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. ITagner, Physiologie, S. 38. f>08 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 Kolliker and JBischoff * (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 every 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 JBischoff 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 place 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 Dumas *, as well as of Hausmann •)•, 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 (-W" — end 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. Bibliography. — A. Leuwenhoeh, Anatomia seu Interiora Rerum, Lugd. Batav. 1687 ; Arcana Naturae, Delphis, 1695 ; Epistolse Physiologicas, Delpliis, 1719; Sur les Animalcules de la Sentence des Auimaux, Philos. Trans. 1672. LedermuUer , l'hysikalische Beobachtungen der Samenthierchen, Nuremberg, 1756. Spallanzani, Nouvelles Re- cherches sur les Decouv. Microscop., Londres, 1769. Gleichen, Abhandlung liber die Samen, und Infu- sionsthierclien, Nuremberg, 1788. Prevost and Dumas, Annal. des Sc. Nat. tom. i. ii. Czermah, Beitrage zur Lehre von den Spermatozoen, Vienna, 1833. Treviranus, in Tiedemann’s Zeitschrift, vol. ii. Von Siehold, in Muller, Archiv. 1836, S. 232. ; 1837, S. 381. Ii IVagner, Fragmente zur Physio- logie der Zeugung; Beitrage .zur Geschichte der Zeugung und Entwickelung ; in den Abhandl. der Konigl. Baeierisch Acad., Munich, 1837. Kolliker, Beitrage zur KenntnissJ der Geschlechtsverhaltnisse und Samenfliissigkeit wirbellosen Thiere, Berlin, 1841 ; Die Bildung der Samenfaden in Blaschen, Nurembg. 1846. I (7?«c/. Wagner and Bud, Leuclcarl.) SENSATION. — (Fr. Sensation; Germ. Empfindung .) — 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 accomplished. 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 Nat. i. p. 182. f Ueber der Mangel der Sameuthierclien beiHaus- thierclien ; Hannover, 1841. J R. Wagner’s Physiology, § 20. Translation by Willis, § 12. * Muller’s Archiv. 1847, S. 436. 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, a 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 feeling 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 papillae 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- 510 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 System, 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 bladder 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 neutralisation 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. Sensibilite ; Germ. j Empflndlick/ceit). — 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 sensibility 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 tothat 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, the 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, quae a levi contactu, parum quae a valente demum causa in brevitatem cietur. Sentientem partem corporis humani 511 SEROUS AND SYNOVIAL MEMBRANES. appello cujus contractus animce 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 priori 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- bility 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 sereuses, Fr.; Serose Haute, Serose Ueberziige, Wasserhaiite, Germ. Membranes synoviales, Fr. ; Synovial-Kapseln, 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 sentientibus et 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 (aw 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 different 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 further 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 micrqscopical elements pervade all these structures, and will there- fore demand some attention. These are the white and yello w fibrous 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. 393. a. White fibrous tissue ; b, Yellow fibrous tissue. -4/1(7 Todd and Bowman, Magnified 320 diame- ers.') 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 striae and another; and since it is also swelled up into one shapeless 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 form, 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 latae ; 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 of volition 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 nuchae, which suspends the ponderous heads of the horned graminivora, the uses of the tissue are ex- emplified 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 Egyptian mummy, I lately found these tissues (after moistening) displaying as perfect a structure as a specimen of yesterday could have done. 513 SEROUS AND SYNOVIAL MEMBRANES. 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 off branches which again unite with the other neighbouring subdivisions of the same kind, so as to form a complicated 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 icar' i tpxi'iv, “ 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 different 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 rough 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. Bursts. — 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 bursce. In the majority of instances, their interior is almost void of contents ; but, in exceptional cases, they contain a considerable quantity of a glairy, mucus-like fluid, which closely resembles that before alluded to, as naming, from its consistence, the synovial membranes. This similarity of their contents was till lately supposed to be the only analogy borne by these structures to the synovial membranes of the articulations ; and hence they have been included by Henle* and other systematic writers in a class of “ Pseudo- serous membranes,” and characterised as lack- ing an epithelium on their inner surface. Reichert f, however, detected a layer of nucleated cells lining their interior. He stripped off a fine layer from this surface under water, and, upon expanding and com- pressing it, found that it was covered by nu- merous darkish nuclei, of somewhat elon- gated shape, and upon which acetic acid * Allgemeine Anatomie, S. 364. f Muller’s Arehiv., 1843. Jahresbericlit fur Mi- kroscopiscli Anatomie, S. 339. L L 514. SEROUS AND SYNOVIAL MEMBRANES. exerted its ordinary effect ; defining their outline, and deepening their colour. But although the existence of a stratum of nuclei was sufficiently distinct, the contour of the cells themselves he does not seem to have determined. The resemblance of these bursae to the membranes which form the especial subject of this article is thus rendered so complete as to deserve a brief notice of their structure in this place ; and the more so, perhaps, that the writer is enabled to add a few details which place this similarity in a still more striking light. The subcutaneous bursa; are the simplest form of these structures, and are very nume- rous in the human subject, but seem much less frequent in other animals. The areolar tissue which immediately in- vests these sacs is, for the most part, very lax, and contains an unusual quantity of the yellow fibrous element, the fibres of which are here of large size. O n removing this from the outer surface of the bursa, it is seen to lie composed of a more compact and whiter tissue, which is tough and much less extensible than the looser tex- ture which surrounds it. The microscope shows this to consist of the white and yellow fibrous tissues. The latter is generally in much less considerable proportion than in the ordinary areolar tissue, while at the same time its constituent fibres are of a smaller size : they possess their ordinary arrangement, and branch and unite sparingly with each other. The white fibrous element is disposed in wavy bands of varying size. These take a course parallel with the surface of the bursa, and, apparently, with few interstices or reti- culations ; thus forming a dense laminated structure, which cannot be broken up without much difficulty. In this structure, at a little distance from the interior, are arranged the blood-vessels, the capillary meshes of which are of tolerably large size, and generally take a more or less quadrangular shape. It is by no means unusual to find one, two, or more fat cells lying comparatively isolated in this mass of tissue, with a loop or curve of capil- lary thrown around them in the ordinary manner. Of the nerves of these membranes I am not qualified to speak. As the white fibrous tissue approaches the internal or free surface which limits the cavity, the bands ap- pear somewhat to differ from this descrip- tion, and become more refractile, acquiring a yellowish colour, and seeming more solid. The interior of the bursa forms a cavity which is very rarely a solitary and regular one, being almost always complicated by the possession of membranes and threads, which run across its interior, and thus shut off in- complete secondary cavities. The number and situation of these is quite irregular in dif- ferent subjects ; and, of the two complications, the first is the most common, giving rise to the production of folds, which project into the general cavity in a manner which maybe com- pared to those processes of dura mater, which form the tentorium and falx cerebri. The surface itself is hard and smooth, and the blade of a knife removes little or nothing from it by scraping with any ordinary force. It deserves to be stated that in examining different specimens differences are seen, both in the amount of the yellow or elastic tissue, and in the degree of condensation of the white element, which ought to be called con- siderable, i. e. that they seem to range, from tough, inextensible, white sacs, of compara- tively simple form and composed of little but white fibrous tissue, to a highly elastic mem- brane, containing a tolerable quantity of the yellow fibrous tissue, and a cavity much com- plicated by numerous threads and processes. How far these diversities are associated with differences of age or habit, it is impossible to state. The whole of this internal surface is covered by a cell-growth, but the exact shape and ar- rangement of the constituent particles are rendered difficult of observation by one or two physical peculiarities not devoid of interest. On examining the free aspect of a thin hori- zontal section, made just below the surface, the dark mass of fibrous tissue upon which the cells are placed, obscured and intersected by the numerous lines which mark its fibres, very seldom allows more than a layer of nu- clei to be observed. And the application of acetic acid, which swells up this tissue, and renders it transparent, at the same time dis- solves the cell-wall, and leaves the dark nu- cleus alone occupying its place. On the other hand, scraping the surface, instead of i obtaining a layer of cells, mutually adherent by the adapted sides of their polygonal mar- j! gin, and easily separated from the subjacent tissue, as is the case with the serous mem- branes,— instead of this, little or nothing is stripped off, save a few scattered cells with much debris and many oil-globules. If j greater violence be used, a portion of the sub- jacent structure is torn off, and offers the ( same optical difficulties as the thin section alluded to. The careful and repeated examination of different portions and fragments, both with and without the application of dilute acetic acid, leads to the following results. I have been unable to verify the existence of a basement membrane, although, on analo- gical grounds, it might perhaps have been ex- , pected that such a structure was present. Or. getting a favourable view of a vertical section, I the surface immediately beneath the epithe- lium appears to be smooth and defined ; but there is nothing which resembles the other surface of a membrane intervening between the cell-growth and the fibrous tissue. The latter appears to be immediately subjacent to the cells, and is continued outwards without any interruption to the surrounding areolar tissue, in which course it is subject to the modifications already described. In one instance only many elongated nu- clei were observed, which were of extreme delicacy, and were seated upon or in a mem- 515 SEROUS AND SYNOVIAL MEMBRANES. brane of little more than their own breadth ; this membrane was prolonged at their oppo- site poles into ribbon- shaped processes, of excessive tenuity and considerable length. Such a description greatly approximates to that given by Mr. Goodsir *, of the torn-up “ germinal membrane ” of the serous tissues ; but I have not studied these objects sufficiently to be able to affirm or deny the complete ap- plicability of his description to them. In the instance where I saw it, I rather inclined to consider it a distortion and elongation of the ordinary epithelia, due to accidental mecha- nical violence, inflicted during the examination of the specimen. The characters of the cells. — The different individual cells which may be found floating in the field of the microscope exhibit great diversities of appearance, so as to offer almost every gradation of cell-growth. The first form visible. {fig. 396. a) is that of a delicate pale, flat, cytoblast, which is either unaffected by the application of acetic acid, or is even rendered somewhat more transparent by it. The next gradation ( h ) is still a cytoblast, i.e. uncomplicated by the addition of an outer cell- wall ; but dilute acetic acid renders it yellowish, and much more distinct. In the next variety (the next stage of development, I think it may safely be termed), two outlines Fig. 396. are visible (c), one of the nucleus or cyto- blast, another of a cell-wall exterior to this ; . and the distance between the two gradually increases in different individuals by an in- crease in the size of the cell, which, however, retains its flattened oval shape. Its contents are either transparent, or very faintly gra- nular : and the succeeding modification mainly consists in the increased granularity of the contents of the cell, and in the assumption of a more or less polygonal outline. This is seen in the figures marked d, e,f g ; and these diagrams also illustrate another detail, viz. that the polygon is anything but a regular one, offering a variety of forms, some of which ap- proximate to a triangle, others to a trapezium or a pentagon. And though sometimes (as in those marked e ), they may be seen apposed in groups of two or even three, yet it will be recollected that many of these forms are phy- sically insusceptible of the neat tesselated 'adaptation which is seen in the hexagonal cells * Anatomical and Pathological Observations, !p. 41. of serous membrane. The wall of the cell is still soluble in acetic acid, and the outline of the nucleus is darkened by its application as usual. The subsequent alterations consist in a gradually increasing flattening and widening, both of the cell and nucleus, but especially of the former, which finally more than doubles the diameter of the polygonal cell, and at the same time reduces its depth to a mere scale. The granular or mottled appearance of the contents before spoken of now reaches its maximum, often forming yellow refractile dots or beads, which appear to be incompletely fluid (h). The nucleus, during this process of flattening, becomes somewhat larger, and much less distinct; and in the larger and more mottled scales, it completely disappears, an effect which might at first be supposed due to the obscuring of its outline by the granular contents, but which is evidently independent of this cause. A further difference is pre- sented by the action of acetic acid, which fails to affect these broad squamous epithelia in any perceptible degree. The arrangement of the cells. — Hitherto we have merely enumerated and distinguished the different forms of cell-growth which may be detected after tearing up casual portions of the tissues lining the cavity : we have next to determine the relative quantities of the differ- ent varieties, and to specify their arrangement, both with respect to each other and to the surface which they clothe. The forms which appear greatly to pre- dominate in quantity, are those represented in the figure as c, d,f. Some of these are nucleated cells of a flattened oval shape, and others are probably similar cells, in a stage immediately subsequent to the preceding, when the oval vesicle becomes more or less an- gular by the lateral pressure of its neighbours opposing its own inherent expansion ; or, re- garding a number of such bodies, when a si- multaneous expansion obliges their yielding walls to adopt that shape which presents the few-est interstices, and thus allows of the greatest amount of mean area. Were the process conducted W'ith mathematical accu- racy, this shape would obviously be a hexagon, and in the serous membranes it will be seen with how few exceptions the cells ap- proximate to that form ; but in the outline of these bursal epithelia, as has been already seen, the oval or circle glides into the polygon by many gradations. Generally speaking, there is but one layer of cells, and these are usually more or less polygonal ; but not unfrequently a few oval ones are seen in close proximity to each other, and only distinguishable by the smaller dis- tance between their nuclei, and the occasional overlapping of their curved borders. The chief exceptions to the unity of the layer are twofold, one at each extremity of the cell-life, so to speak. For instance, pale flat cytoblasts (a), in sparing quantity, some- times underlie the stratum ; while, on the other hand, it is often covered by the very- large polygonal squames ( h ). In either case, L l 2 516 SEROUS AND SYNOVIAL MEMBRANES. it is almost impossible to observe both these different layers in situ, from the transparency and flatness of the objects just named causing them to be effectually shrouded and lost in the outline of the granular polygonal layer ; but, from various reasons, I have little doubt that the preceding description may be re- garded as tolerably correct. It is especially countenanced by these facts, that in looking directly upon the free surface, I have never seen cells referrible to either of the two ex- tremes, but always such as from their shape, their size, and the mutual distances of their nuclei, would be included in the varieties (c, d,f) ; while, nevertheless, a careful tearing up of the same specimen often afforded the cytoblasts and scales. The latter were in much greater quantity than the former, but whether they existed over the whole surface of the bursa, or on particular parts only, I am unprepared to state. And whether the cyto- blasts chiefly underlie the oval or the poly- gonal forms, is a question equally impossible to answer satisfactorily, yet by no means so insignificant an inquiry as it may seem at first sight. On the whole, their usual appearance in conjunction with the younger forms, and their comparative absence from the polygonal- celled serous membranes, somewhat tend to associate them more with the oval than with the polygonal epithelia. The sublendinous bursa:. — It frequently happens that, where tendons in passing to their insertion lie upon a bone, the action of the muscle with which they are continuous gives rise to considerable friction of the two surfaces against each other: and, in some cases, the projecting surface of the bone is even made the pulley by means of which the direction of the muscle’s action is altered, through a similar change in the course of the tendon ; a condition which necessarily implies a yet greater amount of resistance and fric- tion. In these circumstances, burs® are found interposed between the osseous and tendinous surfaces. These bursae have* hitherto been regarded as in all respects similar to the subcutaneous sacs just de- scribed, and the possession of an epithelial lining has been denied them equally with these. But while they apparently present the same form, that of a shut sac, continuous with itself in every part, and are, in the majority of in- stances, indistinguishable from them by the naked eye, they are yet separated from them by important differences. They present, it is true, a cell-growth analogous to that de- scribed in the preceding structures ; but they * Since writing the above, I have been informed that a description of these structures, somewhat re- sembling that given by the writer, has appeared in a provincial German periodical of a few months’ earlier date. I have been unable to meet with it however. So also, the account which I have given of Synovial Membranes must not be understood as claiming any priority. I believe that priority (and probably something more) belongs to Mr. Rainey ; a report of whose paper has appeared in the “ Pro- ceedings of the Royal Society,” a publication which I have found difficult of access. differ from these in the extent of surfac eon which that growth obtains, in the nature of the tissues which are substituted where it is absent, and, in a lesser degree, in the general characters of the membrane where it is pre- sent : the general effect of these differences being greatly to liken tbe anatomy of these structures to that of the joints. On laying open one of the least complicated of these bursae, such as they are generally seen in the dog and cat, we gain entrance to a simple cavity, which everywhere possesses a smooth and shining interior. Above is the tendon, below the periosteum of the bone ; on either side, a delicate continuous membrane separates it from the neighbouring areolar tissue. It might be expecteil that this mem- brane covered the neighbouring opposed sur- faces of tendon and periosteum ; and, indeed, the description usually given by authors affirms the existence of such a covering, to which it attributes the smoothness of their surfaces. But this is not the case : a careful examination of these structures with the microscope dis- tinctly shows that their surfaces of friction are quite devoid of this membrane, and have assumed more or less of the structure of cartilage. The membrane, then, may be described as preserving the continuity of the inner surface of the bursae in the interval between the two ij rubbing surfaces. It is attached to the ten- ' don and periosteum by a mingling of its areolar tissue with these structures. Like its neighbouring areolar tissue, it is extremely jjl elastic and delicate ; so that its tenuity often equals that of the serous membranes. It is plentifully supplied with blood-vessels; and, generally, there is a considerable amount or adipose tissue on its attached surface, the capillaries of which are arranged in the samej manner as those in the bursae previously men- tioned, or those which supply the fat cells of the so-called “ Haversian glands ” in the joints : — viz. the same capillary plexus, which! immediately underlies the epithelium, giver1 off' occasional loops to surround the adipose vesicles. The epithelium itself resembles that | of the subcutaneous bursae in the intimacy o. its adhesion to the subjacent tissue, as well as in the comparatively slight eonnectioi which subsists between the cells themselves S but it appears to differ from it in the greate quantity of the oval cells and cytoblasts, o the former especially : and in the immediat neighbourhood of the fat vesicles this shap,! seems to predominate to the comparative ex elusion of polygonal forms. In the human subject, the surface of bon on which the tendon plays often presents covering of what has all the appearance of fibrous tissue mingled with cartilage, c “ fibro-cartilage and even in smaller animal! (as the cat), in whom the tissue offers n visible difference from the neighbouring per osteum, its intimate structure exhibits a sim lar transition. The bursa beneath the tendc’ of the obturator internus, where this tun over the border of the ischium in its pr SEROUS AND SYNOVIAL MEMBRANES. 517 gress towards the trochanter of the femur, is a convenient one for examination. On making a thin section parallel to the osseous surface, it is found that the bands of the white fibrous element which constitute the periosteum are considerably changed where they line the bursae. They are much less wavy than usual, and, at the same time, have become much more brittle and transparent. Besides be- coming more linear, the markings have altered in another respect, viz. they are much less frequent, and are placed at more regular dis- tances. The ordinary epithelium which else- where lines the cavity has disappeared, and, in its stead, we recognise a great number of cells irregularly scattered over the surface of the specimen ; although even now one may perhaps trace an approach to a longitudinal arrangement in their greater proximity in this direction. These cells, in respect of their solidity, their somewhat angular shape, their colourless transparency, and refractility, greatly resemble those seen in articular cartilage. They are, in fact, cartilage corpuscles. But although exactly on the surface these cells are somewhat flattened, and scattered with com- parative irregularity, this appearance by no means extends any depth in the tissue. A slight alteration of the focus shows that, im- mediately beneath the surface, corpuscles are not only less numerous, but also assume a dis- tinctly linear arrangement.; and form somewhat interrupted longitudinal rows, which chiefly occupy the interstices of the altered bands of white fibrous tissue. The corpuscles them- selves are here more angular and elongated- By further altering the focus, and obtaining a deeper view, the lines marking these sur- faces are seen to be crossed by others ; and a closer inspection reveals the existence of two strata : one, the superficial layer just ex- amined, of which the lines are in the direction of motion, or transverse to this border of the ischium ; and another deeper layer, which lies at right angles to the preceding, and im- mediately covers the bone. In the latter, the i same corpuscles exist, but in rather fewer numbers. The application of acetic acid slowly I swells and dissolves the intercellular sub- stance, and renders the cells more distinct, but does not deepen their colour. After a considerable interval of time, it attacks the : corpuscles themselves, and renders them in- visible ; apparently more from its effect on their relations to the refractility of the surrounding substance, than from a real so- lution. In like manner, the under surface of the tendon offers a similar cellular structure, and a corresponding, but much less considerable, modification of the fibrous tissue itself. But this change, which, on the surface, is so well marked, gradually diminishes as one examines successive and deeper horizontal sections ; and, finally, at a certain depth, the intercellu- lar substance altogether loses its cartilaginous characters, the cells themselves vanish, and the tendon completely resumes its ordinary structure. The crossing of two strata at right angles to each other, which is witnessed in the modified periosteum, is a frequent anatomical peculiarity of the original tissue, and not essential to the modification. And something very similar is seen in the tendon. The tendinous bundles to which the several mus- cular fibres are attached, are successively received into the border of the oblique ten- don ; and very frequently, in joining it, a Fig. 397. don. From the Cat. a, superficial stratum ; b, deeper layer lying at an oblique angle to- the preceding. (. Magnified about 180 diameters .) certain proportion of their fibres swerve aside from its track, scatter themselves, and strengthen the cord as a whole, by cross- ing its surface at a varying angle, and form- ing a thin stratum superficial to it. Where the tendon assumes the peculiarities just al- luded to, the markings and corpuscles of this superficial layer are seen decussating those of the larger and deeper mass which take the direction of the tendon. This crossing of two strata is indicated inyfg. 397. The chief differences between the cells on the surface and those at a greater depth have been already indicated ; viz., that the former are more numerous, flatter, and more oval. But the shapes and appearances of the deeper layer deserve further consideration, since they present the phenomena of a fissiparous genesis of cells, which the upper stratum does not ; so that it is perhaps difficult to avoid attributing the increase of numbers and alter- ation of shape which is seen near the surface to the gradual advance of the multiplied cor- puscles in that direction. The stages of the process are the same as may be observed in other tissues. An elongation of the nucleus is followed by an hour-glass constriction of its middle ; a dark line across the corpuscle then testifies to the fission of both cell and nucleus ; and, finally, the two new cells separate, and their walls surround the nucleus at a more equal distance in every part. Most of these steps may be observed in fig. 397. i, l 3 518 SEROUS AND SYNOVIAL MEMBRANES. The conjecture just mentioned derives con- siderable support from a comparison of their structure in the adult with their younger and foetal conditions in the same animal. In the latter especially, the quantity of cell-growth on the surface is so great, as, in respect of mere continuousness, almost to merit the appellation of an epithelium. But though its constituent cells lack the angularity, and somewhat the size, of those which belong to the inferior strata ; yet, like the same cells in the adult, they are quite distinguishable from the epithelial covering of the bursa, not only by their appearances with and with- out acetic acid, but by the distance to which the shifting focus follows them. At successive depths, they are seen to become somewhat larger, more angular, and wider apart ; and the same process of fissiparous multiplication may be detected in them as in the adult cells. We shall see that these differences at the different stages of the animal’s life experience a close parallel in articular cartilage. In a few instances, I have witnessed another form of cell-multiplication in this tissue. It occurred in one or two cats of a few months’ age, but I cannot say whether it is limited to any particular period of their life. It is represented in fig. 398, and con- Fig. 398. Compound. Cells of Bursal Fibro-cartilage. From the young Cat. ( Magnified 400 diameters.') sists of an oval or elongated vesicle or cell of limitary membrane, which is filled with, and usually more or less bulged by, a number of cytoblasts. These compound vesicles were sparingly scattered through the carti- lage-like tendon and periosteum ; similar masses of cytoblasts, of a spherical form, may occasionally be seen in young articular carti- lage ; and, indeed, instances of this form of cell-multiplication might be adduced from many structures, temporary, permanent, and morbid, but their introduction would be foreign to the province of this article. The constitution of the synovial sheaths of tendons resembles that of these bursse in many respects ; and, on the whole, offers a still closer approximation to the structure of a joint. In many places, the sheath consists only of a delicate transparent membrane, the tenuity of which approaches that of the serous membranes, and which, like them, rests on a stratum of loose areolar tissue, and is reflected from the parietes of the cavity to the tendon where it enters it. Here they possess an oval or slightly angular epithelium, which constitutes only one layer. But almost every such tendon, in some part or other of its course, offers an alteration of direction implying considerable friction, and effected either by a projection of bone, or by a pulley of thick and strong fascia. Such are the grooves and posterior carpal ligament for the extensors at the back of the wrist. And here is again discovered the condition which was previously stated of the obturator tendon, but with some slight modifications ; firstly, that the approximation to the structure of cartilage, here visible to the naked eye, affects equally the whole periphery of the tendon, instead of being limited, as heretofore, to one of its surfaces ; and, secondly, that the cell- growth is more plenteous, sufficiently so as io offer scarcely a point of the surface unoc- cupied by cells; of which the shape, size, and disposition almost exactly resemble those of the surface of articular cartilage in the young mammal or the adult reptile. In the cartilaginous-looking portions of the sheath, a similar, but less extensive depth of cell-growth obtains ; and I believe I have recognised the same condition in the surface of the crucial ligaments of the knee-joint. The vessels of these synovial sheaths are very numerous, ami their capillaries exhibit a tortuous arrangement which is identical with that witnessed in the articular synovial mem- branes hereafter to be described. But this copious supply of vessels is limited to the delicate membranous portions of the sheath, and to those mesentery-like reflections which here and there pass from the parietes to the contained tendon. Wherever the tendons are subject to much friction, and evince the partially cartilaginous structure already de- scribed, there the vessels are absent from those superficial and cell-containing strata, and, so far as I know, are limited to the deeper and non-cellular parts of the tendon. Synovial Membranes. — The synovial membranes are structures exceedingly analo- gous to the preceding, and consist of a layer of cell-growth, which covers the inner surface of the ligaments that connect the different segments of the skeleton in the diarthrodial joints, and which thus partially lines the |j “ cavity ” or interior of these articulations. They have been usually described as re- sembling the bursa mucosa both in the nature and consistence of their secretion, and in jj their constant adherence to the morphological j character of a shut sac ; while the absence of epithelium predicated of these burs®, has been laid down as the chief anatomical dis- 1 tinction between the two structures. And, on the other hand, they have been likened to , the serous membranes by the common pos- session of a tesselated epithelium, ami by their continuity over the whole surface o! the cavity and its contents; while they have been severed from them by the difference in the composition and consistence of their secretion, — a viscid alkaline fluid, instead of a more limpid and neutral one. Most of these statements can only be received with some modification. 519 SEROUS AND SYNOVIAL MEMBRANES. In the following sketch, such details as are more or less common to the synovial mem- branes in general will chiefly be treated of. For a description of their more salient pecu- liarities in the different joints, the reader is referred to the articles headed with the names of the several articulations. The epithelium of these structures presents characters which afford some grounds for distinguishing it both from that of the bursal and serous membranes. It forms, for the most part, but one layer, the forms of the constituent cells of which vary to the same extent as those witnessed in the burs®. But the broad, squamous, polygonal epithelia are comparatively rare ; and in by far the larger extent of its surface, the predominant shape is that of a slightly flattened spheroidal, or oval, or somewhat angular cell, such as the majority of those represented in fig. 399, in The vessels of the membrane are exceedingly numerous, and its capillaries form a horizontal plexus, which ramifies immediately beneath the epithelium in the areolar tissue just men- tioned. The great vascularity of the tissue has long been known, but the capillaries are not only very numerous, but offer a much more remarkable peculiarity.* They are greatly increased in their length, so as to be everywhere extremely tortuous, and some- times this tortuosity almost amounts to a spiral disposition. On looking at the broad surface of well-injected specimens, an exag- geration of this disposition here and there, gives rise to small patches of tortuous capil- laries ; but the arrangement is clearly a general one, and extends, in some degree, to every in- dividual capillary of the net-work. But though the length of these vessels in a given space is thus greatly augmented, the frequency of their Fig. 399. Epithelium, of Synovial Membranes, a, free surface seen in situ; b, separated cells. ( Magnified 200 diameters.') some of which are seen decussations of two convex outlines, caused by the margin of one cell slightly overlapping that of its neighbour. Acetic acid exerts an unusual effect upon the cell-membrane, swelling up its outline very much before dissolving or rupturing it ; an appearance which obtains in the more flat- tened and polygonal epithelia of the serous membranes, but, so far as I have seen, in a much smaller degree. Like those of the bursas, they are firmly attached to the sub- jacent tissue, and possess little mutual ad- hesion ; though here and there a cluster of two or three more polygonal than usual may be found. Cytoblasts are rare, the cells ap- pearing to be completed by the addition of the outer membrane when yet extremely small, (Jig. 399. b.) All these peculiarities might perhaps be generalized in the statement, that the cells which cover the general surface of these membranes are in a younger and more active stage of cell-life than those of the bursae. And a slight yet perceptible difference in the same respect has been already indicated as existing between the subcutaneous and sub- tendinous members of this class of structures. Immediately beneath these cells lies a stratum of looser areolar tissue, which connects the membrane with the inner aspect of the liga- ments of the joint. It includes little of the yellow fibrous tissue, and its meshes are comparatively few and close : exteriorly, they unite, by a gradation of structure, with the dense white fibrous tissue of which the liga- ments are composed. Fig. 400. Capillaries of the Synovial Membrane, projecting by their convex border over the articular cartilage. From the human finger. a, artery ; v, vein. (_ Magnified 40 diameters.) inosculations does not seem to experience a corresponding increase. Their tortuous form is represented mfig. 400. The preceding description of the vascular, fibrous, and areolar constituents of synovial membrane applies only to the simplest form of that tissue, which consists of a plain flat expanse of membrane. In special joints, as well as in special parts of every joint, each of them experiences modifications deserving of notice. Over the cartilage of the articulation, for instance, all of these cease ; and deferring for the present a consideration of the ana- logous structure which here supplies the place of epithelium, we come to consider the anatomy of the synovial membrane where it reaches the border of articular cartilage. The fibrous tissue exterior to the mem- * I have here to express great obligations to Mr. Quekett, of the Royal College of Surgeons, since his kindness supplied me both with specimens, and with many further details of this arrangement, till then unknown to me. The joint from which fig. 400. was sketched, was taken from a hand admirably in- jected by him. L L 4 520 SEROUS AND SYNOVIAL MEMBRANES. brane, and with which its areolar tissue is mingled, passes to the side of the articular cartilage, and immediately becomes inextri- cably interlaced with its fibrous tissue or pe- richondrium. The plexus of capillaries, some- what more tortuous here than on the plain surface, runs up to the edge of the cartilage, or may even advance a very short distance over it, where it is not exposed to friction during the movements of the joint. Its various branches then suddenly stop short, and each taking a looped course, returns upon itself in the same tortuous manner. This distribution is represented in Jig. 400. The layer of epithelium offers equally re- markable appearances ; a few of its particles are very slightly flattened, but most of them are spherical, and of very various sizes, of which some are extremely large. All of the larger contain a pale and rather flattened nucleus, which is in contact with a part of their inner surface. The cells are also of singular delicacy and transparency, and are, to all appearance, distended with a fluid, the refractility and colour of which closely ap- proximate to that of water. The areolar tissue which forms the foundation of the membrane being diverted at this point to join with the ligaments and perichondrium, the vessels are left comparatively naked ; and so far as I have been able to make out, upon these bare capillaries the cells are seated, without the intervention of any membrane. They thus form what is indeed a covering for the vessels (since there is no part of them upon which large or small cells or cytoblasts are not placed) ; but, as is evident from their shape only, they constitute a layer in a very different sense from those in which the epi- thelium of the serous membranes does so. In some of the more complex joints, another modification occurs, which is in many respects very similar to this, viz. distinct folds or invo- lutions of synovial membrane, which project into the cavity of the joint. The best in- stances of this are seen in the knee-joint, where they form what are called the “mucous” and “ alar ligaments.” The folds which con- stitute these come off horizontally from the synovial membrane in the front of the articu- lation, but with a considerable interval be- tween their upper and lower layers, which is filled with adipose tissue. They contain besides, a plexus of vessels, of which some, lying immediately beneath the membrane, ramify in the flexuous manner described ; while the deeper are distributed to the fat vesicles, throwing loops around each in the manner peculiar to this tissue. A very small quantity of fine areolar tissue is present, chiefly as a covering and protection to the vessels. Gradually going backwards, they lose their adipose tissue, and taper to an edge, which accurately fits into the interstice be- tween the condyles of the femur and head of the tibia. Here the upper and under layers come into contact, and in the middle line pursue their way backwards as the ligamen- tum mucosum, a flat, thin duplication of the membrane ; until, finally, at the anterior ter- mination of the notch between the condyles, they terminate by joining the synovial cover- ing and fibres of the neighbouring crucial ligament. On either side of the middle line, the process of synovial membrane terminates, by a convex margin, a little beyond the point where it ceases to contain fat : these are the “ alar ligaments.” On the ligamentum mucosum, the cells are of a similar appearance to those of the general surface of the membrane, though they seem rather more delicate and transparent. The projecting edge of the so-called alar ligaments offers still more marked characters. Owing to the congestion of its vessels from some unknown cause, it is frequently seen after death of a bright red colour, its surface is minutely rough or velvety, and its consist- ence soft or almost pulpy. On examining it with the microscope, many minute and villus- like processes are seen studding its border, and directed backwards towards the commis- sure of the femoral and tibial articular sur- faces. These processes appear to consist chiefly or entirely of two structures, viz. bloodvessels and cells. The vessels are nu- merous long tortuous capillaries, which pass to the margin of the villus, anti then, taking an arched or looped course, return upon themselves, and pass, with few anastomoses, into the general plexus of the fold. The cells, equally with the vessels, resemble those al- ready described as existing at the border of the articular cartilage. They are of various sizes, the more numerous and larger ones are spherical, transparent, and contain a tolerably large nucleus : they are distended with fluid, and the slightest pressure on their singularly delicate cell-wall bursts the cell, and causes the fluid to exude. In this condition, the action of the surrounding water seems to impress on it something like a partial coagu- lation, giving it a mottled or minutely granular appearance. The smaller cells exhibit the same shape and general appearances, except that the nucleus is proportionally larger ; a few cyto- blasts are also present, and a granular blastema completes the covering of the vessels. One would fancy this to be a favourable situation for verifying the existence of a basement membrane, did such a structure exist here: but I have been unable to detect it. On the contrary, I have often seen the curved border of a large cell seated directly on a capillary, the dark line of the wall of this tube alone separating its cavity from the delicate sphere in contact with it. Fig. 401. represents such a villus-shaped process. The relation of the synovial membranes to the diarthrodial cartilages, or the question of “ Whether the membrane is continued over the articular surface of the cartilages, or not?” has been long a matter of dispute among anatomists. But a resume of the history ol this discussion having been already given in an earlier part of the work, the reader is 521 SEROUS AND SYNOVIAL MEMBRANES. referred to it for a statement of the arguments on both sides of this interesting question up to that date. (See Articulation.) The rapid progress of histological anatomy, and the use of the microscope, have since thrown much light on the subject, yet perhaps with a less immediate effect than might have been anticipated. Fig. 401. Villus-sliaped process from the free Margin of the Alar Ligament. From the Cat. ( Magnified 300 diameters.') From the impossibility of injecting the vessels of the synovial membrane beyond the margin of the cartilage, it had long been known that they did not extend over this articular surface ; and one might almost imagine that a looped termination of the vessels in this situation must have been sus- pected. And the researches of Mr. Toynbee* concerning the vascular arrangements of the deep or osseous surface of the cartilaginous lamina, showed a similar disposition of the vessels in this situation. Everywhere a thin plate of bone, impermeated by vessels, sepa- rates them from actual contact with the car- tilage ; and the capillaries themselves, as they approach this osseous lamella, appear some- what dilated, and finally, taking an arched course, they return upon themselves into the neighbouring extremity of the bone. The truth of this description as a whole is readily tested and confirmed by examining any part of the substance of a diarthrodial cartilage. Such a fragment, torn up in any manner, and submitted to a sufficiently high magnifying * Philosophical Transactions, 1841. power, evinces no trace whatever of vessels, or of their easily recognisable contents. But although the absence of vessels is thus proved, the absence of the synovial membrane by no means necessarily follows. The less so, indeed, that modern physiological research exhibits almost all structures as essentially extra-vascular : i. e. it shows that in almost all, the characteristic substance of their tissue is separated from their vessels by an interval ; an interval which, though always minute, is nevertheless an appreciable, and often a measurable one, and which the pabulum de- rived from the blood has to traverse in order to effect their nutrition. The continuity of the synovial membrane, or the reverse, can only be settled in one way ; to wit, by an appeal to observation : and since the naked eye fails to give sufficient information, it remains to the microscope to decide its presence on, or absence from the articular surface. Henle* affirms the continuity of the mem- brane over the cartilage, as a tesselated epi- thelial covering of nucleated cells, resembling those which line the serous membranes and the other parts of the joint. Professors Todd and Bowman in their more recent work), state that they have been unable to detect such a covering in the adult, but that, on the contrary, they have usually observed an irregular surface, presenting no cells beyond the ordinary scattered corpuscles of the cartilage. In the foetus, however, they have found it readily visible. A comparative examination of those car- tilages in different genera of animals, or in the same animal at different stages of life, partly confirms, partly modifies, each of these state- ments. In a specimen of diarthrodial cartilage, taken from an adult mammal, if we make a thin section parallel to the articular surface, and look directly upon this part of the interior of the joint, we see appearances similar to those represented in fig. 402. A number of cartilage corpuscles, at irregular distances from each other, and separated by the intercellular sub- stance of this tissue, constitute the only cell-formation visible, and the existence of similar corpuscles at varying depths in the substance of the cartilage may easily be verified. The chief difference noticeable between the deeper and more superficial of these cells is, that those in the latter situation contain in their interior many yellow and highly refractile granules, which are of com- paratively uniform size, and occupy their cavity about midway between their tolerably central nucleus and the inner surface of the cell-membrane. This appearance becomes still more manifest as the corpuscles approach the articular surface. A thin vertical section of the cartilage shows that the cells are in greater numbers near this surface, and the edge which borders the joint exhibits an irre- * Allgemeine Anatomie, S. 226, et seq. f The Physiological Anatomy and Physiology of Man, vol. i. p. 90. 522 SEROUS AND SYNOVIAL MEMBRANES. gular outline, from which cells may often be seen projecting. The attrition which these appearances would seem to denote appears to be exerted upon the cells equally with the interstitial substance of the cartilage, but is more difficult to verify in the former tissue, since such a cell that has suffered a partial destruction of its form, has, at the same time, lost a valuable optical means of detection. Occasionally, however, as in fig. 402., on looking Fig. 402. Free surface of Articular Cartilage. From the elbow- joint of an adult Cat. ( Magnified 200 diameters.') directly at the free surface of the tissue, we see a darkish nucleus, lying very superficially, and surrounded by a clear space. In all pro- bability, this was such a cell ground down to a hemispherical cavity. More rarely, a profile view of such a hemisphere is obtained. On examining similar specimens from ani- mals of the same species at successively younger ages, the intercellular substance becomes gradually more scanty, and finally altogether disappears, leaving the whole of the surface occupied by a cell-growth, which is a covering, but notan epithelium; unless we extend the application of this objectionable word, and call the whole cartilage itself, what indeed we might with perfect truth, “ a modified epithelium.” The accuracy of this description of the cartilage of very young animals is easily veri- fied by a vertical section ; and, if it be made sufficiently deep, it will include a portion of another structure, and a different process, with which it may be advantageous to com- pare it. At the furthest extremity of such a section, we see the ossification of temporary cartilage actively going forward. First comes the formation of cancelli, and the enclosure of cells ; next, a little nearer the articular surface, the greatly dilated cells are arranged in closely-packed rows, the bottoms of which rest in cups of bone, which will soon become cancelli. Still approaching the articular sur- face, we find the cartilage corpuscles smaller, more refractile, and flatter ; but vet with a distinctly linear arrangement. The loss of this arrangement in rows seems to indicate the limit of the ossifying cartilage and the commencement of the articular lamina; and I have often seen the distinction still further marked out by a horizontal fissure in this situation, — the effect of accidental violence, no doubt, but perhaps indicative of some deficiency of cohesion dependent on structure. Immediately beyond this situation, the cartilage cells are scattered irregularly but closely through the transparent intercellular substance. They are angular and refractile, and they contain a large granular nucleus. Many of them are elongated, and somewhat spindle-shaped, while many more are tri- angular ; and these two forms appear respec- tively to precede and follow a fissiparous multiplication of their numbers, the constancy and accuracy of which would almost allow of its being termed a bisection. The details of this process have been already alluded to in speaking of the subtendinous burs®, and are too well known to need any recapitulation here. From hence onwards to the articular surface, the cells become more numerous, larger, and less angular in shape, until finally, on the surface itself, the increase of their number and size results in a continuous layer. But the appearances of this multipli- cation are not seen in the most superficial stratum of all, although the prevalence of the hemispherical outline still indicates the binary nature of the fission ; whence it seems pro- bable, that just upon the surface the increase is one of bulk only. In fig. 403. is represented a vertical view of the superficial and of a deeper layer, which contrasts them in the particulars just men- Fig. 403. Articular Cartilage from a Kitten four days old. a, arrangement of cells on the free surface ; b, a deeper stratum. ( Magnified about 250 diameters.) tioned. The condition of these cartilages in the adult fishes and reptiles closely resembles this description of their appearance in the young mammal, in the complete cellularity of their surface. For the knowledge of this fact, I am indebted to Mr. Quekett. Serous Membranes.- — -The serous mem- branes, presenting a structure which offers a close general parallel with that of the pre- ceding tissues, are yet contrasted with them in many important respects. The first and most obvious distinction, and one on which the other structural differences are to a great extent based, is, that in place of their main- taining a direct relation to the locomotive apparatus, or being connected with the seg- ments of the skeleton in the diartbrodial joints, the organs to which they are more im- mediately subservient are those concerned in the organic or vegetative life. The serous membranes of the human body are seven in number ; three being median and single, while two are double and lateral. They are the arachnoid, pericardium, and peritoneum, with the pleurae and tunic® 523 SEROUS AND SYNOVIAL MEMBRANES. vaginales. Thus they are connected with the organs of respiration, circulation, diges- tion, generation, and innervation. Perhaps, under this accurate allotment of serous mem- branes to these several functions, many im- portant analogies lie hidden, but the inter- pretation of these hieroglyphics of nature scarcely belongs to the present elementary sketch ; and it will be both safer and more profitable to regard their relations to the three first of these functions as being deter- mined mainly by the necessity of movement which a high development of any one of them implies, although the general protection which mobility affords must not be lost sight of. The relation of a separate membrane to the function of generation seems, as it were, the accidental result of position : the tunica vaginalis, an offshoot of the perito- neum, is prolonged from it by the testicle in its descent from out of the abdominal cavity, and is subsequently isolated by a degene- ration of the serous membrane into areolar tissue along the spermatic cord which con- nects this gland with the interior of the belly. So the arrangement of the arachnoid around the nervous centre is, perhaps, more related to the comparative delicacy of its structure, and the movements inseparable from circulation, than to the function of in- nervation itself. A prominent feature in the anatomy of all these structures is the remarkable continuity of surface which they exhibit. With a single exception, indeed, their interior surface, like that of the subcutaneous bursae, is everywhere a continuous one ; and hence the definition of a serous membrane always includes the statement, that it is “a shut sac,” while this peculiarity of arrangement is constituted their “ morphological character.” A complete description of the serous mem- branes would comprise two chief divisions of the subject. One of these would, include the relative situation and arrangement of the neighbouring textures, as well as the various folds or processes by which the membranes preserve their continuity in the intervals between the viscera which they cover and the cavities which they line. The other would limit attention to their general structure ; and to any variations in the nature, proportions, or arrangement of their constituent tissues, which may be obtained by a comparison of the several membranes with each other. In the present instance, the latter only of these divisions will be briefly attempted ; for the former of the two, the reader is referred to the articles under the several headings of Pleura, Peritoneum, Heart, Nervous Centres, Testicle, &c. The epithelium of serous membranes con- sists of flattened cells. The shape of most of these is roundish-polygonal, and many of them closely approximate to the hexagonal form : and they are arranged in a single layer, so as to form a tesselated pavement, which everywhere constitutes the free sur- face of the membrane. Their diameter varies considerably, but, generally speaking, is about one 1000th of an inch. Their depth is nearly one-fourth of this width; but it tapers awa3r towards the edge of the particle, and is greatest at its centre, where it is usually somewhat bulged by the presence of a tole- rably large nucleus, which is contained in the cavity of the cell, but is placed nearer its inferior or attached surface than the opposite or free one. This nucleus is of an oval or spheroidal form, and contains a single bright refractile spot or nucleolus ; but not unfre- quently there are two of these. Besides the nucleus, the cell includes a small quantity of contents, which are of somewhat viscid consistence, and are usually almost trans- parent, but sometimes, and especially after exposure to the action of water, become mottled or faintly granular. The attachment of these cells to each other is very remark- able, but their adhesion to the textures on which they are placed is much less considera- ble ; and this preponderance of their adhesion in the horizontal direction renders it very easy to strip off a number of them, and ex- hibit the layer which they form by their union. In this circumstance they offer a marked and probably important difference from the cells which clothe the interior of bursae and synovial membranes. Acetic acid exerts its ordinary effects, causing the cells to swell out, and thus defining their polygonal shape more accurately than before. The exceptions to these general cha- racters are few. In one instance, namely in the peritoneum of the female, the form of the cellular covering is said to differ from the above ; the ciliated epithelium, which lines the Fallopian tubes, being con- tinued for an exceedingly short distance over the margins of their fimbriated extre- mities. The size of the cells also expe- riences slight variations : thus, they are largest in the peritoneum, and smaller in the pericardium, especially in its visceral layer. Their arrangement as a single cellular stratum is also interrupted in some parts : thus, the arachnoid exhibits one or two layers, the outer of which is composed of cells which are more flattened and elongated than usual. Basement membrane. — The existence of a basement membrane immediately beneath these cells is still a matter of doubt. It rests chiefly on the affirmation of Professors Todd and Bowman, and Goodsir — high authorities on such a question. By the first of these ana- tomists it is regarded as “ a continuous trans- parent membrane of excessive tenuity,” and “homogenous, or nearly so.”* The latter describes it in much the same terms, but considers it sometimes, or generally, separable into component cells, which are of a rhom- boidal and extremely flattened shape ; and it has been named by him as the Germinal Membrane.\ As somewhat corroborative of these statements, it may be urged, that such a structure is easily seen to exist in the very * Op. cit. p. 130. f Ibid. p. 41. 524 SEROUS AND SYNOVIAL MEMBRANES. similar mucous membranes ; and that the cell-lining of the arteries, which becomes deficient where these pass into the capillaries, and thus leaves the latter vessels with a simple membranous wall, seems to exhibit a kind of natural analysis of a yet more similar compound structure. And it must be recol- lected that failure of recognition is by no means a satisfactory argument against the presence of such a delicate structure ; i. e. that one such affirmation as those above ought to outweigh many denials. Still those who, after repeated and careful examination, have failed to recognise it, are no doubt justified in continuing to doubt its existence. Areolar Tissue. — A stratum of areolar tissue occupies the outer or inferior surface of the preceding cellular structure, and in- cludes in and amongst its meshes the remain- ing constituents of the serous membrane. The inner surface of this lamina is smooth and condensed, where it immediately under- lies the cells : exteriorly, it can scarcely be considered as possessing a defined surface, but gradually merges into the areolar tissue of the neighbouring organs. The separation of the two structures is, however, generally indicated by an interval, in which their tex- ture is somewhat looser. This is called the “ subserous cellular tissue .” As this layer constitutes the chief thick- ness of the membrane, and is the constituent on which its physical properties are mainly dependent ; so its varieties of constitution and arrangement, correlatively with the re- quisite differences of these properties, are both numerous and important. One of the most common of these altera- tions is an augmented quantity of the yellow fibrous element ; indeed, in many portions of the serous membranes, this increase is so considerable as to constitute a continuous special layer of the elastic fibre, which occu- pies a horizontal plane immediately beneath the epithelium. The fibres of this layer are delicate, of a smaller diameter, and somewhat paler colour, than those which are found in the ordinary areolar tissue : they branch at acute angles in every direction, and unite with those in the immediate neighbourhood ; while beneath, and partly amongst them, are seen the white fibrous bundles, with their ordinary arrangement. The advantage of such a pre- dominance of the yellow element is obvious : it confers an increased elasticity on the mem- brane, and better adapts it for distention, or for a return to its original bulk after this force is removed. The situations in which it is found are in exact conformity with this view : m the peritoneum, which lines the anterior abdominal wall and covers the blad- der, it attains its maximum ; in the detached folds of the mesentery, in the costal pleura, and in the so-called suspensory ligaments of the liver, it is still very prominent ; but on the posterior wall of the belly, and in the serous membranes where they cover many of the viscera, such as the heart, brain, lungs, liver, &c., it is almost completely deficient. On the lungs, the necessity of its presence is probably superseded by the large quantity, both of the texture and of the property, which is inherent in these organs themselves : the remaining viscera are all organs of a size which is either little variable, or of uniform variety. In the areolar tissue beneath the spinal and ce- rebral arachnoid, another modification occurs. Between the vascular pia mater, which closely envelopes the nervous centre, descending in- to its sinuosities of surface, and the visceral layer of the arachnoid, a considerable interval exists, in which the meshes of this tissue are exceedingly long and lax ; while, in many parts, the distance between them is so much in- creased as to form cavities, which have re- ceived the name of “ the subarachnoid spaces.” They are filled with the fluid of the same name ; and by its presence the visceral and parietal layers of the serous membrane are maintained in contact, pressure generally be- comes equalised, and large portions of the nervous centre hang suspended in fluid. The chief interruption to this arrangement obtains at the summit of the cerebral convolutions, where the arachnoid and pia mater are strongly adherent to each other : but the more minute description of these spaces or cavities belongs to the special anatomy of these membranes. The fat cells which are so often deposited in the intervals of areolar tissue frequently occupy its meshes in the serous membranes. In most of these instances, however, it would be more correct to regard the subserous or connecting areolar tissue as the seat of the deposit, than that more condensed portion of it, to which an artificial separation would limit the term “ serous membrane.” It is plentifully found in connection with both layers of the peritoneum, while it is comparative!}' absent from the arachnoid. In the case of the other serous membranes, the parietal layer is that which is most liable to its presence ; indeed, on the lungs, it appears to be completely and invariably absent. This latter circumstance has been ascribed to a supposed local antago- nism of respiration to the deposit, analogous to that which is known to be exerted by this process generally. But this supposition seems quite untenable, since the lungs themselves are not nourished by the blood which it is their function to depurate, but by the ordinary arterial fluid, which exhibits the usual changes in the bronchial veins ; and one can hardly imagine respiration to exert an influence on the tissue, apart from, or greater than that which it exerts on its blood. Here, as else- where, the necessities of movement seem to be the circumstances which chiefly regulate the locality of the deposit : excessive mobility, as in the scrotum, penis, and eyelids, seeming to contraindicate the formation of adipose tissue. The amount present in these membranes generally exhibits a direct relation with that which is contained in the whole body. The vessels of the serous membranes ramify in their areolar tissue, and by their numerous anastomoses with each other constitute a 525 SEROUS AND SYNOVIAL MEMBRANES. plexiform arrangement, which occupies, for the most part, a plane parallel to the surface of the membrane. Lymphatics in considerable numbers exist in the same situation. Nerves. — Little is known of the manner in which these tissues generally are supplied with nerves. In the case of most of them, anatomy sufficiently shows that the amount of nervous tissue which they receive for distribution is but small ; and at present, even the aid of the microscope does not seem materially to affect this statement. The observations of Pur- kinje *, and more recently of Volkrnann j- and Rainey £, however, agree in verifying the exist- ence of a large number of nerves in connec- tion with the cerebral and spinal arachnoid. They appear not to communicate with the roots of the spinal nerves, but to pertain ex- clusively to the sympathetic system ; and they branch and form plexuses in the areolar tissue beneath the arachnoid. But how far they are related to this membrane, or the serous mem- branes generally, or whether they belong more to the pia mater and other subjacent textures, seems at present incompletely determined, and is a question which will require an ex- tended comparison with the other serous tissues. The very painful nature of the diseases of these membranes is singularly contrasted with the slight amount of sensation of which they are capable in a state of health. It is pro- bable that, as in the bowels, bones, and some other tissues, this contrast mainly depends on the minutiae of the anatomical arrangements of the nerves relatively to the tissue. In the serous membrane, this may perhaps receive some explanation wThen we call to mind that almost every morbid change to which they are liable has the immediate effect of converting a smooth, moist, and plane surface into one the nature and disposition of which implies a vast amount of friction, and the abnormal character of which draws this important dis- tinction between it and other normal surfaces which rub with far more force : viz. that no provision has been made to guard against it. And if the arrangement of the nerves, what- ever be its other features, allots to them as great a proximity to the surface as is granted to the vessels, it seems tolerably obvious, that any such friction would, in reality, amount to a serious injury of these delicate nervous filaments, and would be quite suffi- cient to account for the intense pain expe- rienced. In addition to the preceding tissues in- cluded in the ordinary enumeration of the se- rous membranes, there are other parts of the body which present structures so closely re- sembling these, as to render it perhaps doubt- ful whether this title can justifiably be with- held from them. The ventricles of the brain are lined by a membrane which exhibits the * Mtiller’s Arcbiv. 1845. f Wagner’s Handworterbucli der Physiologie, artikel “ Nervenphysiologie.” } Medico-Chirurgical Transactions for the year 1845. characteristic smooth and shining appearance of the serous tissues ; the posterior surface of the cornea is occupied by a similar layer ; and, according to Henle, there are consider- able grounds for conjecturing the existence of some such structure on the inner surface of the membranous labyrinth and semicircular canals. But without here entering into the question of a possible transition of mucous into serous membranes being represented by these tissues, it will be sufficient to point out that while the ventricular and corneal mem- branes present a stratum of epithelial cells analogous to those described above, they are almost or entirely deficient in the important element of areolar tissue, — and that this constitutes a difference according to which the line of distinction is drawn, excluding them from the serous membranes. The epi- thelium which lines the general surface of the cerebral ventricles consists of flattened poly- gonal cells which are covered with ciliae ; but where it passes over the choroid plexus, it varies so considerably from this description as to merit a special notice. The choroid plexus occupies the descending cornua of the lateral ventricles, and forms the margins of the velum interpositum, the inti- mate structure of which it resembles in many respects. It consists chiefly of an interlace- ment of capillaries and capillary arteries. The former are of large size and great tortuosity ; and, in this last respect, they are similar to those of the synovial membrane already de- scribed. A little areolar tissue surrounds and supports the vessels, and a stratum of cells covers the surface of the plexus. Besides these structures, a large number of nerves have been described by Mr. Rainey as rami- fying beneath the cells, but Purkinje and other observers deny the existence of nerves in this situation. Concerning the shapes of the cells which cover the plexus, similar dif- ferences of opinion and description obtain ; Henle*', Valentin f, and other high authorities speak of them as being in general polygonal, but somewhat flattened and curved where they cover the fringes of the plexus ; while, on the other hand, Mr. Rainey attributes to them a spherical shape and faintly granular con- tents. The following are tlieir appearances as noted by the writer of this article. At the margins of the fringes are seen many long and tortuous capillaries, the gene- ral course of which is parallel to the border of the plexus, and interrupted by few anasto- moses. No basement membrane can be de- tected interposed between these vessels and the cells. The cells themselves are of a sphe- rical shape, and of the very large size repre- sented in the sketch {fig. 404-.), many of them being one five-hundredth of an inch in diameter, a magnitude rarely paralleled by any cells but those of the adipose tissue : they contain a tolerably large nucleus in contact with their inner surface. Where exposed to the slightest pressure, they take a polygonal shape, but I * Allgemeine Anatomie, S. 228. t Wagner’s Handworterbucli, artikel “ Gewebe.” 526 SEROUS AND SYNOVIAL MEMBRANES. have never seen such an appearance except under these circumstances ; and at the edge of the fringe, which is usually more or less shielded from pressure by the prominence of the neighbouring surface receiving the weight of the upper lamina of glass, this perfect glo- bularity is readily verified. The cell-wall is extremely delicate and thin; its contents are Cells of the Choroid Plexus. From the adult Cat- The upper figure represents their arrangement in situ ; in the lower, a, nuclei of ruptured cells ; b, cells detached. ( Magnified 320 diameters.') fluid, and usually nearly transparent, and of a refractility not much different from that of water. So great is the delicacy of the mem- brane, and so little aid to observation is given by its colour or refractility, that at first it requires careful scrutiny before its pre- sence is verified ; and its recognition is often retarded by the excess of light which the modern achromatic condenser affords. From this, which is the ordinary size, they pass by few gradations to a plentiful blastema, which fills up the interstices, and more or less com- pletes the covering of the vessels. On tear- ing up such a fringe, most of these cells dis- appear, and their collapsed membranous walls may be found here and there, flattened and folded upon themselves, or burst at one ex- tremity, and giving vent at the rupture to a faintly granular mass and their nucleus. The nuclei found in multitudes in such a specimen are round and pale, and contain granular matter and a single small bright yellow nu- cleolus ; or, rarely, there are two such spots. Many of these free nuclei exhibit a flattened or truncated surface, which indicates the ex- tremity previously seated on the inner surface of the cell. Whatever may be the import of this pecu- liar structure, it is interesting to observe how closely, both in the arrangement of the vessels and the structure of the cell-covering, it re- sembles the synovial fringes previously de- scribed. The view of Mr. Rainey, that these spherical cells are nerve vesicles, seems to rest at present on the very insufficient basis of a slight external resemblance. But it appears difficult to infer such complicated functions as are sustained by the nervous matter from such simple physical properties as sphericity, faint granularity, and the like, unaided by other structural analogies. Development of serous membranes. — The steps of this process are little known, a circum- stance which seems partly to depend on the extreme readiness with which it occurs, partly on the comparative simplicity of its nature : the cell being retained as the permanent form of the tissue, the mere apposition of a number of these in connection with a surface of areolar tissue is all that is required to complete the visible phenomena of its deve- lopment. In the animal kingdom, serous membranes are almost invariably present. They mostly appear in immediate connection with some higher development of the several viscera around which they are grouped. In this manner, first the peritoneum, and next the pericardium and arachnoid, appear. The first indication of the pericardium is in the mol- lusca, and its appearance seems to be imme- diately preceded by a mechanical provision of a very different kind, although perhaps of similar import : the heart is suspended in the centre of a muscular cord, which is attached by its two extremities, and thus fixes the viscus and steadies its movements. The peritoneum and pleurae are united in one in the reptiles ; afterwards, the latter membranes are shut off by the formation of a diaphragm. Tiie tunica vaginalis is absent in those animals, in whom the testicles occupy a position within the belly. Generally, there is the same obvious relation of their presence to mechanical uses which is seen in the human subject. But the ciliated serous membranes of many reptiles, and the urinating pericardium of cephalopods, offer, at present, such great and inexplicable dif- ferences from the human serous membranes, that one might almost doubt, especially in the latter of these instances, how far textures contrasted by such manifest differences of structure, and probably of function, can justi- fiably be called by the same name. In the human foetus, their development is also little understood. This period of life, however, adds the amnion to the list of serous membranes, the structure of which it closely resembles. Its cavity is occupied by a saline and albuminous fluid in large quantity. It is subject to fluctuations in amount, and one or two analyses appear to show that the proportion of albumen which it contains is considerably diminished in ad- vanced pregnancy. Development by friction. — Besides these two forms, the development of some of these structures is witnessed in another condition, perhaps more peculiar than either; viz., in answer to the application of mechanical force. The subcutaneous bursae which are ordinarily found over some of the various prominences of bone indicate the nature of their relation to these localities by their reproduction after 527 SEROUS AND SYNOVIAL MEMBRANES. excision ; while in other situations of the same kind, but in which they are not usually present, the application of long-continued pressure and friction gives rise to their pro- duction. If we add to these phenomena the development of diarthrodial false joints, it will appear that a certain amount of pressure is capable of determining the formation of a cavity, and the growth of a cell-covered membrane, which secretes a synovial fluid ; and that, exerted in a higher degree upon the more resisting bones, it clothes their extremities with a substance which presents all the appearances of cartilage. The presence of blood plasma is no doubt a necessary con- dition of both processes, but in neither are the subsequent minute changes known. In the case of the areolar tissue which is con- verted into a bursa, we may indeed infer, that mechanical violence exerted upon it would produce an increase of vascularity or an active congestion ; but we can scarcely conjecture bow this alone should result in an increased vital activity, in the removal of some of the partitions of its net-work, the com- pression of others, the formation of a cavity, and the regular cell-covering of its inner surface. But while the production of this structure in answer to pressure is exceedingly inte- resting, and offers a remarkable analogy to its general development in the foetus and animal kingdom, there is perhaps a danger of our exaggerating the resemblance, and becoming too mechanical in our views. On closer consideration, their ordinary and extraor- dinary formation will be found to exhibit a difference, which may teach us caution in our conclusions as to the method in which me- chanical force acts. It is this : that while, in the latter case, their development appears to provide for a want already experienced ; in the former instance, — in the young embryo, — we may observe a very similar development oc- curring, which is a provision for a necessity that has never yet existed, and cannot there- fore be the immediate cause. Physiology of the serous and synovial mem- branes.— At present, the physiological import of the preceding minute structural details is so little recognised or understood, as to leave scarcely anything to be said under this divi- sion of the subject. But, in this respect, these textures present so close a parallel to many others in the human bod}', that to con- sider this imperfect knowledge as demanding a complete silence, would be to interpose an insuperable barrier to almost all conclusions on any physiological subject. In truth, the question of the abstract truth or falsity of physiological conjectures by no means involves the question of their usefulness ; and the difficulty of retaining mere details, the danger of considering them as essentially knowledge, the possibility of allowing a philosophic sus- pension of judgment to merge into sloth- fulness,— all these circumstances taken to- gether perhaps claim that such anatomical minutiae should at least be considered with a view to their explanation ; even while they demand that the various shades of probability possessed by these conjectural explanations should, as far as possible, receive their due estimation ; and that their adoption should never interrupt the collection of fresh facts. Some attempt has already been made to discriminate between the physical and vital properties of these membranes ; and the mechanical advantages conferred by some of the former were enumerated as constituting their most prominent use. Their secretory function has next to be considered, together with any relations which this process may possibly bear to the organism generally, as the further use of these structures. A most important feature, and one which belongs to all these membranes, is their pe- culiar arrangement. The general statement, that they are so disposed as to form shut sacs, has been already alluded to, and was at no late period considered their characteristic definition. But as mere form could scarcely be thought of such essential importance, various attempts have been made to explain this morphological character, by referring it to some other term, which should either ex- press a real cause, or should approximate to this by enunciating some physiological purpose itself implying the fact. Many of these, however, such as its being the result of the universal presence of epithelium, &c., are little more than re-statements of the fact in another form. But to the exception of the female peritoneum, long known, must now be added (unless the definition of these structures be arbitrarily extended so as to include many varieties of cartilage) all the articular synovial membranes, and many of the bursas ; in which the interruption to the continuity of the membrane constitutes the phrase “ shut sac,” an inaccurate expression as applied to them. In short, all that the term really implies is, that there is no visible outlet by which the cavities these tissues form, or assist to form, can communicate with the exterior of the body. And even in the case of the apparent exception at the extremity of the Fallopian tube, it is exceedingly probable that the small size of the aperture of communication, the ciliated lining which it possesses, and the direction in which the current of ciliary motion sets, constitute it, in effect, a closure. The internal position of the serous membranes is followed hy this important physiological consequence, that the contents of their cavities are never directly eliminated from the body ; but that such portions of the substance of the membranes, or of its sepa- rated products, as may become effete in the course of the vital changes, can only be dis- charged from the system after a previous reception into the general mass of the circu- lating fluid. This fact at once establishes a broad line of distinction between these tissues, and the mucous membranes, or true glands ; while at the same time it tends to prove that their secretion, whatever it may be, possesses little of the deleterious quality, or excretory 528 SEROUS AND SYNOVIAL MEMBRANES. composition, which marks many of the pro- ducts of the mucous system. Contrast of serous and synovial membranes. — The shape of the cell of serous membrane may afford some indications of its history. In flatness, it occupies a position about mid- way between the squamous outer epithelial particles of the skin, and the columnar in- testinal cells. The conditions which lead to the excessive horizontal extension of the former appear to be, a vertical pressure acting upon them during their growth, and aided by an eva- poration which diminishes the cell-contents, themselves originally small in quantity. On the other hand, the immediate cause of the prismatic or columnar shape is, no doubt, a horizontal pressure mutually exerted by the growing cells themselves. This pressure appears generally to limit their diameter to that of the contained nucleus ; a smaller diameter, which implies the existence of a greater number of cells in a given space. Their longitudinal extension similarly involves a greater amount of contents ; so that, on the whole, this might be termed the highest form of cell-growth, the development and filling of a large number of cells simultaneously.* Comparing the serous epithelium with these two extremes, we may recognise in its flattened shape the effect of vertical pressure on a cell containing but little in its cavity ; while the comparatively small number of cells in a given space, and the oneness of the layer, are further indications of the moderate activity of the cell-growth. The uniform size and poly- gonal shape of the constituent cells, together with their great mutual adhesion by their edges, or in the horizontal plane; — these are circumstances which seem to point to the simultaneous development of the whole layer, and to the previous causes of flatness determining its growth almost exclusively in this direction. The little aid afforded by the composition of these cells is derived from observations which are chiefly of a negative kind : since they show that the cells do not offer any con- siderable chemical differences from the liquor sanguinis, but consist chiefly of albuminous and fibrinous materials. The nature of the serous secretion seems little understood. In health, the quantity of fluid present in the interior of the membranes is only sufficient to moisten their free surface ; while where its amount is enough for the purposes of analysis, the accompanying dis- eased conditions would prohibit our assuming its identity with the normal fluid, even if the supposition were not rendered untenable by the varying composition of the fluids them- selves. But, on the whole, the very small quantity of fluid naturally present, its compa- ratively limpid consistence and transparent appearance, together with the absence of the cell-form in which secretions are involved, probably refer it immediately to the simple * For some further remarks on the subject of cell-growth, the reader is referred to a future article, “ Stomach and Lxtisstinal 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 f has pointed out that the different serous membranes seem to effect this “filtration” with different de- grees of fineness. Arid, possibly, the dimi- nution of albumen noticed in the liquor anniii of advanced pregnancy may be ascribed to a similar subtraction from this fluid by the serous membrane in the cavity of which it is situated. The share which the cells as such take in this process can scarcely be conjec- tured ; but that their disposition in such a form is not absolutely 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 affinity,” “ 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 name 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 Physiologie des Menschen, Band 1., S. 601. f Report on the Progress of Human Anatomy (Brit, and For. Review, year 1843-4, p. 10.) 529 SEROUS AND SYNOVIAL MEMBRANES. 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 gliding 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 op- 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 offer 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 cells, 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 physical 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 which 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 gro wth, 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 func- 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 disproportionaliy greater. However carefully the surfaces of diarthrodial cartilage may be lubricated by the synovial fluid, a very slight knowledge of 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 in Jig. 402) 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 which is interposed between this “ debris ” and the M JI 530 SEROUS AND SYNOVIAL MEMBRANES. vessels at the osseous surface (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 probability, 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 synovial membranes ; but many of the preceding remarks, mutatis mutandis, are applicable to them. The close resemblance of the choroid plexus 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 blood, 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 perhaps 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 synovial 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 plexus, 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 Anatomy 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 possible 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-growth 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. Serous or dropsical effusions. — One ot 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 of 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 ot earlier occurrence in the history of the dis- * Physiological Anatomy and Physiology of Man, vol. i. p. 131. 531 SEROUS AND SYNOVIAL MEMBRANES. 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 eases, 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 affirms 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 cases 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 likelihood, 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 effu- 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 fulfils, 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 the 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 column 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. Physical 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 limpidity of water to the viscidity of synovia j 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 m si 2 532 SEROUS AND SYNOVIAL MEMBRANES. exactly alike in this respect. The following table exhibits four analyses, contrasted with that of the serum of the blood : — Water - Albumen Extractive - Fat Salts - Serum of Blood. Phthi- sis.* Asci- tes, f Ascites. Ascites. 905 78 4-2 3-8 9 988 3 I9 988 0-9 10 956 29 9 7 8 704 290 2 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 quantitative 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 Eat -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 anaemias, 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 front 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 Bibra, Dublanc, and Lecanu, are quoted at second-hand. J 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 then- 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 fibrinous effusions. — A large number of the fluids which are found effused in the interior of the serous mem- branes offer characters which essentially dis- tinguish them from the dropsical effusions above described. The first and most pro- minent differences are those presented uy their appearance and chemical composition. 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 ease is mentioned as “ Hydrocephalus.” 533 SEROUS AND SYNOVIAL MEMBRANES. To these physical differences accede equally important pathological 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 inflammation ; 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 susceptibility 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 i i.e. 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 complete organization, being converted either into 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. Im the earliest stage of inflammation, and before effusion 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 parts 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 inflammatory, — 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 ; still less, where present, is its amount to be considered any measure of the intensity of the process. An alteration in the texture of the mem- brane it3elf is probably immediately subsequent to this injection in the order of time, and is generally seen in connection with it. Its 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 thickness, 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 limpid consistence. It is true that we are rarely able to verify this transparency in the exsudation of the large? 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 uniforndy 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 u-hich it has thus already begun to separate- The composition of this effused fluid exhibits M m 3 534 SEROUS AND SYNOVIAL MEMBRANES. great 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. AY ater - Fibrine - Albumen Extractive Eat Salts Liquor San- Fibrinous Ef- guinis. fusion. - 906 934-936 3-4 -984 77 51-88 The composition 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 quantity 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 like 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 villi 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 fihrine 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 :s 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 earliest to be organized. Rarely the completeness of this coagulation leaves the serous part entirely 535 SEROUS AND SYNOVIAL MEMBRANES. devoid of fibrine, and, in respect of composi- tion, closely resembling some of the dropsical 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 irregular 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 uniform 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 to 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 approximate 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 -r although there is no reason to believe that it confers an ab- stract immunity as respects the inflammatory process. The suppurative inflammation 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 membraniform exsudation, resembling the wall of an abscess, to which the altered tissue may, under these circumstances, be fairly com- si si 4 536 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 wails 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 complete ab- sorption. The pus., deprived of certain of its constituents, is slowly transformed into a mortar- 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 ofthem 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 ” effusion, first recognised by Lasnnec, 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 portion is only capable of a very slow absorption, and prior to this event it passes through many gradations of colour and appearance. Ge- nerali)', it slowly loses its red colour .; but in the case of the haemorrhagic 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 haemorrhage 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 occurrence, 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 * Handbuch dev Patliologisclien Anatomie, Band ii. S. 28, SEROUS AND SYNOVIAL MEMBRANES. 537 a slight effusion, which is followed by an ad- hesion of its visceral and parietal layers ; an effect 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. Tubercle. — 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 granularity 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 parieties 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 limited 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-cartilaginous thickening, which is itself the developenient 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. Cysts 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 limpid and transparent, and are composed of water, with blood salts (chiefly chloride of sodium), and an exceedingly small quantity of albumen. Yet the effusion 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 within 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, which is formed by this covering where it becomes continuous with 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 known 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 539 SEROUS AND SYNOVIAL MEMBRANES. few weeks’ or months’ standing, they may vary somewhat from this description by the possession of a rough surface 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-f- 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 offered 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 anil 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 alcohoi, and were swelled out into a transparent mass by acetic acid. The substances described b}' 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 Entstehimg fester Korper in den von Sy- novialkauten gebildeten Holden. J Oesterreiclie Medizinische Jalirbueher, Bd. xxxix. S. 261. Anatomiscbe Untersuchung einer so- genannterHydatiden Gescliwulst des Schleimbeutels der Beugesebnen 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 neighbouring areolar tissue by pressure into a membranous form, similar to that seen in the sac of an aneurism.) The synovial membrane, where it covered the tendons, w'as 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, little 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 uniformly 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 affections 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- 640 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 acquired 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 li kely, 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 Home j- 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. t 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 Ilyrtl 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 verified the con- version of bone into these structures. The change was partial, and the vessels seem the immediate agents of the process, since not only did a superficial stratum of cartilage occupy the whole surface of a pedunculated and cartilaginous structure, hut 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 physical adaptation is absent. From these circum- stances it seems probable that the absorption which is accomplished in the former case by ithe 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. ToddJ 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 Brinton.) 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 Generates de Medecine, vol. iv. p. 161. t Anatomical and Pathological Observations, j Medical Gazette, 1847. owe their name udog) 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 inetacarpo-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, probably', 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- line, 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 42 SESAMOID BONES. stouter towards the external part than to- wards the inner or that which is in contact with the long flexor tendon. A microscopic examination of sections, taken in the three cardinal directions, shows that they possess much the same minute structure as other similarly shaped bones. The lacunae 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 laminae, or conversely as though the ossification had extended up in laminae between the tendinous fibres. The lacunae 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 fractured 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 any 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 Yol. III. p. 850. fhj. 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 metamorphosis 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. Ollier 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 heads 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 peroneus 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 quadruped mam- |l malia than in man ; and they seem to be largest in animals that are digitigrade in their progression. I have not had an opportunity of scrutinizing their condition in the Quadru- inana ; 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 fifth toe, which 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 Mammalia a pair occurs opposite every metacarpo- and I; metatarso-phalangeal joint. The two bones of the pairs are not unfrequently anchylossd 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 ftbro-cartilage. In Reptiles they are wanting. The patella exists in all placental Mammals, 543 SEVENTH PAIR OF NERVES. blit is absent in many Marsupials. In Birds it is usually, but not invariably, present ; there are even sometimes two, one placed above another. In those aquatic birds which have the tuberosity of the tibia prolonged upwards 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 So/ipedes, 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 Ruminants 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 little bones. (5. R. Pitlard .) SEVENTH PAIR OF NERVES (Sie- benter Nerv, derm. ; 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 difficulty 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 * Yol. I. p. 286. + Meckel. X Yol. 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 ; 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 offer the essential structure of nervous centres ; and include, in addition 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 then- 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 auditorius 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 differences, 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- i 14 SEVENTH PAIR OF NERVES fibres. From the fact of its lesser consistence, it is frequently termed the “portio 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 line, 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 Physiologie du Systeme Nerveux, tom. ii. p. 84. t Traite Complet de l’Anatomie du Systfeme Nerveux Cerebro-spinal. Premiere Partie. surface of the petrous portion of the tem- poral bone, where it enters the internal audi- tory meatus. In this 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 encephalic nerves are traced. It is difficult to follow it any depth 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. Th e first 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. 515 SEVENTH PAIR OF NERVES. 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 passing 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 probabilit}', 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 unravelling 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 bane. — The facial nerve, entering the aqumductus Failopii 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 Failopii 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- pying 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 Failopii 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 Fai- lopii. The swelling 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 superficial petrosal nerve is connected with the facial. Tracing it forwards from the intumescence, it is seen to pass at once through the neighbouring hiatus Failopii, 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 Gasserian ganglion 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 tnus 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 Failopii, whence 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 540 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 rotun- dum and ovale : and appearing on the inferior surface of the base of the skull, it immediately unites with the otic ganglion 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 which 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 aquaeductus 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 lies 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-pharyp- geal just below the ganglion of Andersch. Longet states that this branch, after its junction with the glosso-pharyngeal, may ge- nerally be traced to the digastric or stylo-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 winch 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, being 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 upwards 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- frontalis muscle, which it supplies : in this course it is covered by a dense fascia, and is 547 SEVENTH PAIR OF NERVES. 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 believed 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 division 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 auriculo-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 bynames, 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 Bonamy have 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 attollens 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. Th e buccal 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 orbicularis 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 downwards 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 supra-maxillary 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 obliquely 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 offer 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- cludes 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.^ 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. 405, 6), shortly after its origin, and Fig. 405. Diagram of the Portio intermedia and its branches. {After Morganti.') * Op. cit. ■j- Report on the Progress of Human Anatomy and Physiology in the year 1844-5. British ana Foreign Medical Review. 549 SEVENTH PAIR OF NERVES. 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 the 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 l-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 (Jig. 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 (k), 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 (m) 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, (Jig. 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 simplified, 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 (fig. 406.) was taken from the left side of a sheep’s head. With as little artificial separation as possible, it represents the arrangement of the ganglion and nerves in situ, 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 Nerves of a Sheep as seen in situ. JIagnifed about 2£ diameters. a, portio dura; b, portio intermedia; c, portio molfis ; e, origin of the superficial petrosal nerves , f 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. Upon 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 Liefemng. Artikel “ Sympathischer Nerv Ganglienstruktur mid Nervenendigung.” 551 SEVENTH PAIR OF NERVES. 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 submaxillarj' 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. Rut these general 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- NS 4 Aimali di Metlicilia. Maggio, 1842. 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 muscles 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 paralysis 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 Natural 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 probability 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 j 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- 1 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 annexes aux organes des sens. I 553 SEVENTH PAIR OF NERVES. 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 facial 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 c onsiderable interval of time. Professor Roux has left a recital of his sensations during a rheumatic facial hemiplegia ; and in his description, which Longet quotes f, 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 perversion 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 Generates de la Medicine, 1843, 1844. f Op. cit. tom. ii. p. 465. 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 facial 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 was 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 js 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 palate : — 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 may 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 which 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 whole, 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 painfully 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- glion 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 of 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- * Lelirbucli der Physiologie, B. ii. S. 673. f Muller’s Archiv. 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 suffer- 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 support 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 555 SEVENTH PAIR OF NERVES. of the portio dura in that larger sense, in which we generally use this word of nerves ; and hence the changes effected 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 hancN of Magendie*, Es- chricht, Lund "j", and LongetJ ; 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 * Leyons sur les Fonctions du Systfeme Nerveux, tom. ii. p. 181. ■j- Dictionnaire des Sciences Medic., Journal Com- plem, tom. xxvi. p. 204. j 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 irritation 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 tympani 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 supposition quite untenable. 556 SHELL. centres, of which the}' form such large and important roots : while, allowing them to be affected 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 Morganti may somewhat supply the deficiency of direct evidence. ILe 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, like 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, we 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 Nervous System. ( William Brinton.) SLIELL.— This term is commonly employed 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 t.heir texture as the envelope of a beetle or a centi- pede. Among radiated animals, the class of Echinodersiata is the only one in which shells are met with ; and these are by nc means universally present throughout the group. In the molluscous series, we meet with shells in every class save the Tunicata ; all the animals of the class Conciiifeba, whe- ther lame/li-branchiafe or pal/io-branchiate, 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 aperture) of the ganglion on the posterior root of a spinal nerve ? SHELL. 557 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 the 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. Serpida, 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 microscopical 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 Moliusea, 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 would 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 Moliusea, and the thinner jointed envelopes of the Crustacea, have been commonly regarded as mere exudations of stony matter, mixed with an animal glue secreted from the membrane which answers to the true skin. The hard axes and sheaths of the Polypifera, how- ever, have been also regarded in the' same light ; and yet, as will hereafter appear, these are un- questionably formed by the consolidation of what was once living tissue. Prom the analogy which the shells of Moliusea and Crustacea bear to the epidermic appendages of higher animals, there would seem reason to believe that the former, like the latter, have then- origin in cells, and that these are afterwards 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, as well fossil as recent ; whilst the degree of 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. Moliusea. — The shells of Moliusea 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 carbonate 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 (fig. 407.) that the prisms themselves appear to be composed of a very homogeneous substance, but that they are separated by definite and strongly-marked lines of division. When such a lamina is submitted to the action of dilute acid, so as to dissolve away the carbonate oflinie, a tolerably firm and consistent membrane is left, which exhibits the prismatic structure just as perfectly as did the original shell (fig. 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 it is then seen that whilst many of them pass Fig. 407. Section of the shell of Pinna parallel to the surface, showing prismatic cellular structure, cut trans- versely. Magnified 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. Magnified 185 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 shells, that the decay of the animal membrane leaves the contained prisms without any con- Fig. 409. 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 of 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 fig. 411.: it is seen that these also exhibit transverse striae of a si- milar aspect. By submitting the edges of the membranous walls of the prismatic cells divided longitudinally (as in fig. 410.) to a high magnifying power, the cause of the transverse SHELL. striation is seen to be a thickening of the cell- wall in those situations ; which will of couise F‘g- 411- 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 laminm along the lines of striation, as shown in the lower part ofyfg.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 mgrina) 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 fig. 412, 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 allied to Pinna. In all the genera of the Margaritacece , 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 559 thickness of the shell is made up of the inter- nal or nacreous layer ; 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 Ostracees the greater part of the shell is composed of a sub-nacreous substance, the successively-formed lamina; of which have very little adhesion to each other ; but every one of these lamina; 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 Pandoridce, which belongs to quite a different section of the class ; and it is curious to ob- serve that the marked difference in the struc- ture of the shells of Pandora and Lyonsia from that of the Anatinidce and other neighbouring families, harmonises completely with the pecu- liar combination of characters presented by the animals of these tw'o 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 Margaritacece, 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 Hanley’s British Mollusca, vol. i. pp. 207, 213. 5G0 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 adistinct 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 arenaria, a careful examination of which shell brings to light nu- merous interesting varieties of cellular organ- isation. Thus in jig. 4 13. we see in one part of Fig. 413. Section of shell of Mya arenaria, showing in one part distinct cellular partitions , with large nuclear spots ; whilst in another part of the same layer , the cell- boundaries 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 Mya, 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 Anomia and Fccten, and generally in C/iama, Cleidothoerus, Fig. 414. Section of the hinge-tooth of Mya arenaria, showing radiating arrangement of carbonate of lime within the cells, and the gradual disappearance of the cell- boundaries, so that the texture becomes homogeneous. Magnified 80 diameters. Tri.gan.ia, 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 fusiform 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 surface has not suffered abrasion. (See fig. 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 Margaritaceee 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. When a piece of nacre is carefully 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, tiie closer will their edges be ; whilst the less the angle which they make with the surface, * Phil. Trans. 1814. SHELL. 56] 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 multitude 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 decalcificalion, which tends to unfold the plaits. There is one shell, however, — the well-known Haliotis splendens , — 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 lustre, although all the calcareous matter has been re- moved from their structure. 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 Loo. 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-nacreous 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 Mytilacece, and with the common Oyster. 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 1-20, 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 Ephippium they are scantily dis- tributed in the internal nacreous lamina ; but in the yellow outer layer they are very abundant (Jig. 415.), forming an irregular net- work, which spreads out in a plane parallel to the surface. In Cleidotheerus chamoides, 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, but 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 Area 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 often pre- sent, in their beaded aspect, indications of a cellular origin, as if they had been formed o o 562 SHELL. by the coalescence of a series of cells arranged in a linear direction. They are generally j Fig. 415. Tubular shell-structure from external surface of Anomia Ephippium. Magnified 250 diameters. most abundant in shells whose exterior has a foliated or sculptured character ; and not un- frequently they may he distinctly seen to pass directly towards the prominences of the sur- face, — as in Lima scahra 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 origin and mode of formation of the membranous shell-structure, it is rather diffi- cult to give an exact account. Possibly, after 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 layer 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/iotis, the nacreous laminae 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 ( fig. 416.), their short diameter not being above l-5000th of an inch. Their boundaries in many parts are very indistinct, or even disappear altogether, so that every gradation can be traced, from the obviously cellular ar- rangement shown in Jig. 412., to the homo- geneous aspect presented by the nacre of bivalve shells. The same cellular structure, anti 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 agency 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 Nautilus. We seem justified in concluding that nacre has everywhere a similar origin ; and if one variety of membranous shell-substance be thus Fig. 416. Cellular structure of nacre of Ilaliotis splendens : the cells cut transversely at a, longitudinally at b, and showing their terminations (with 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; which 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 liquefy or dissolve away, unless supported by 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 Margaritacece 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 Perna we not unfre- quently find, between the calcified layers, membranous laminae consisting chiefly ot 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. SHELL. 563 would seem to be peculiarly abundant, being apparently of the same kind as that of which the bi/ssus 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 laminae, each of which is in contact with the internal surface of the preceding, and extends beyond it, — does not express the whole 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 oi Jig. 417. will clearly show the mode in which the operation is effected. This figure Fig. 417. Vertical section of shell of TJnio occidens, near the lip, showing the arrangement of the outei or prismatic, and the internal or nacreous layers: aar, bd, cd, successive lines of growth; d, maigin of the \alve Magnified 8 diameters. represents a section of one of the valves of Unio occidens, taken perpendicularly 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 a a', bb', 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 we 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 well seen in the Oyster; with this difference, that the successive layers have but a comparatively slight adhesion to each other. The shells of Terebratulce, and of several 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 (5). 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 other genera of Braehiopoda, or Palliobran- cluate 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, (Jig. 418. a .) Fig. 418. Portion of the shell of Terebratula australis, showing the orifices of the perforations, and the peculiar structure of the shell : at a the shell is traversed by the section ; at l is shown its internal surface. 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 by 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. psitlacea (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 (fig. 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. bullata, 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 ( fig . 419.): the free extremi- Fig. 419. Decalcified membrane of shell of Terebratula australis, showing the ccecal tubuli, which occupy the perfora- tions of the shell : the tubuli are filled with minute cells. Magnified 150 diameters. ties of these appendages have distinct ccecal terminations ; and when a sufficient magnify- ing power is employed, it is found that their contents are distinctly cellular, resembling the cells in the interior of glandular follicles. These coecal tubuli lie 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 coecal 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 ccecal appendages. The perforations are wanting in a large proportion of the very numerous species of fossil Terebratula; ; 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 Ortkis and Spirifer, the distinction has to be established between the perforated and noil- perforated species ; whilst in Atrypa (to which the recent Ter. psiltacea properly belongs), all the species are destitute of perforations. There is not, by any means, the same amount of diversity 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 usually 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. 384), 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. Gray -J- as the result of rhom- boidal crystallisation ; each layer being eom- * See a Paper on the Subdivision of the Genus Terebratula, by Mr. J. Morris, in the Journal of the Geological Society, vol. ii. p. 382. t Phil. Trans. 1833, p. 790. SHELL. 565 posed of thin laminaj 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 Jig. 420. Although the intimate structure of Fig. 420. ortion of fractured surface of middle layer of Cyprcea mauritiana, showing laminae composed of prismatic cells obliquely crossing one another. Magnified 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 plane 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- iiotis, 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- liotis 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 ( Helix 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 Pteropoda, 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 layers 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 considered 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 SMELL. which connect these plates. The Sepiostaire having been formerly described in some detail (vol. i., p. 546), it will only be re- quisite 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 class have yet been examined ; it may, however, be stated as an interesting result of microscopic ob- servation, that the “ spathose guard” of the Belemnile 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 Septaria gigantea, the great sand-boring Teredo of Sumatra. The structure of the shells of the testa- ceous Annelida, and of the pedunculate Cirrho- poda, does not essentially differ from that of Mollusca ; but in most of the sessile Cir- rhopods, such as the common Balanus, 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, magnified o diameters. diploe has been described by Mr. J. E. Gray* as existing between the laminae of Ostrea purpurea; but in no other shells of existing Mollusca has any approach to it been yet discovered. A very regular cancellated structure, however, is exhibited in the singular extinct group of Budistes, where it makes up nearly the entire thickness of the shell (Jig. 421.). The cancelli are usually short hexa- gonal prisms, terminated at each end by a flat partition ; consequently, a section taken in one direction (fig. 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- * Magazine of Zoology and Botany, vol. ii. p. 228. verse partitions ( fig. 422.). The cancelli are frequently occupied by calcareous infiltra- Fig. 422. Cancellated structure from the shell of Hippurite, as seen in vertical section. Magnified 5 diameters, tion ; which might lead to the belief that, like the cells of the Pinna, they were so consolidated in the living 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 Mollusca and the sessile Cirrhopoda. And it may be added that, by the same evidence, the place of the curious Pleurorhyncus hibernicus, a fossil which has been assigned to a different tnbe by almost every naturalist who has examined it, would unhesitatingly be determined as amongst the Budistes. Echinodcrmata . — The structure of the skeleton in this class is entirely different from that which we have found to be cha- racteristic of the Mollusca ; 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 Crinoidea, and in the scattered calcareous deposits which are met with in the integuments and in the tentacula of the Hole- thurida. The elementary structure of the skeleton of the Echinodcrmata may be described as a nct-worlc, composed of calcareous and animal matter intimately united ; the former, however, being greatly predominant. In this net-work, the interspaces or areola, and the solid structure which surrounds them, may bear an extremely variable proportion to one another ; so that, in two masses of equal size, the one or the other may greatly pre- SHELL. 567 dominate, and the texture may have either a remarkable lightness and porosity, or a con- siderable degree of compactness and brittle- ness. We may take the plates making up the shell of the Echinus as presenting a typical form of this structure ; from which the transition is easy towards either the more solid or the more open character which it elsewhere presents. When we obtain a very thin slice of one of these plates, taken parallel to the surface of the shell, we find that it is composed of a lamina, apparently in itself destitute of structure, perforated with con- siderable regularity by apertures of a circular or oval form. The diameter of these aper- tures (Jig. 423.) varies to a certain extent in Fig. 423. Tii in Lamina o f shell of Echinus, showing its areolar structure: a a, portions of subjacent layer; bh, fractured bases of columns connecting the super- posed laminse. Magnified 164 diameters. different parts of the same shell, the reticula- tion being much coarser in the inner than in the outer layers : from numerous measure- ments, the extremes may be stated at about l-450th and l-2500th of an inch. The en- tire thickness of the shell is made up of an immense number of such plates, which lie parallel to each other, but not in contact ; for they are separated from each other by little pillars, which rise up vertically from each plate to support the next, and which thus connect the different plates whilst hold- ing them apart. The broken bases or ends of these minute pillars are commonly to be seen upon the surfaces of the perforated plates, at the spots intermediate between three or four of the apertures (Jig. 423. b, b). The suc- cessive plates are always so disposed, that the centres of the perforations of one shall corre- spond with the intermediate solid structure of the next (Jig. 423. a, a) ; and their trans- parency is such, that, when we have reduced a section to such a degree of thinness as to contain a small number of the reticulated layers, it is easy, by a proper adjustment of the focus of the microscope, to bring either one of them into distinct view. In whatever direction we slice the shell of the Echinus, we always meet with a sort of reticulated structure ; for if our section be parallel to the surface of the plates, it brings into view one or more of the perforated laminae just described; whilst, if it be per- pendicular to the surface, it passes vertically through a series of these laminae, and in the direction of the pillars that connect them, which thus constitute an areolar structure of a tolerably regular form. The testa is thus of an extremely porous character, the areolae having the freest communication with each other. Even in the living state, however, the areolae appear to be empty, the ingress of the fluid with which the surface of the shell is in contact being prevented by the delicate membrane that covers it. At the same time, it possesses a remarkable degree of strength, in proportion to the amount of solid matter employed in its construction ; for every part at the same time supports, and is supported, by the surrounding fabric. The skeleton of the Echinodermata con- tains very little organic matter. When it is submitted to the action of dilute acid, so that the calcareous matter is removed, the re- siduum is very small in amount ; indeed, unless the acid be so weak as only just to dissolve the carbonate of lime, the organic matter also will be dissolved, and no animal basis will be apparent. When, however, it is obtained in a state fit for examination, it is found to possess the reticular structure of the calcareous shell ; the meshes or areolae being bounded by a substance in which a fibrous appearance, intermingled with granules, may be discerned under a sufficiently high magnifying power, as was first pointed out by Professor Valentin. This tissue bears a close resemblance to the areolar tissue of higher animals ; and the shell may probably be con- sidered as formed, not by the consolidation of the cells of the epidermis, as in the Mol- lusca, but by the calcification of the fibro- areolar tissue of the true skin. This calcifi- cation of areolar or simply fibrous tissue, by the deposit of mineral substance, not in the meshes of areolae, but in intimate union with the organic basis, is a condition of much interest to the physiologist ; for it presents us with an example, even in this low grade of the animal kingdom, of a process which seems to have an important share in the formation and growth of bone, viz. the progressive calcification of the fibrous tissue of the periosteum.* Not only the entire shell, but the frame- work by which the teeth of the Echinus are enclosed and supported, is composed of a calcareous reticulation similar to that now described ; nor is it confined to these solid structures. It has been pointed out by Pro- fessor Valentin, that the buccal membrane contains isolated patches of extreme de- licacy ; and the same eminent observer has detected a most beautiful example of this * See Dr. Sharpey’s Introduction to the Fifth Edition of Dr. Quaiu’s Anatomy, p. 148, et seq. o o 4 563 SHELL. structure in the calcareous rosette, with which, as long since observed by Monro, the sucker at the extremity of each am- bulacral tube is furnished. But it is in the spines with which the shell is beset, that the most remarkable displays of it are to be met with ; for it is there disposed in connection with solid ribs or pillars, which increase the strength of these organs, in such a manner as to constitute a most regular and elaborate pattern, which appears to differ in every distinct species. When we make a thin transverse section of almost any spine be- longing to the genus Echinus, we are at once made aware of the existence of a number of concentric layers, arranged in a manner that strongly reminds us of the layers of wood in the stem of an exogenous tree. The number of these layers is extremely variable ; depending, not merely upon the age of the spine, but upon the part of its length from which the section is taken. The centre of the spine (y%. 424. a.) is filled up Fig. 424. Transverse section o f spine o f Echinus : a, medullary centre ; hb, first layer of solid pillars; cc, eld, ee, ff successive rings of growth. Magnified 45 diameters. with the same kind of calcareous net-work as that of which the shell is composed ; and this is sometimes so delicate, as to appear as if made up by the interlacement of mere threads. This medullary centre is bounded by a row, more or less circular according to the form of the spine (which is sometimes angular), of open spots ( b , b, b), in which it is deficient : these, on a cursory inspection, might be supposed, from their transparency, to be void spaces ; but a closer inspection makes it evident that they are the sections of a circular row of solid ribs or pillars, which form the exterior of every layer. Their solidity becomes very obvious when we either examine a section of a spine whose substance is pervaded (as frequently happens) with a deep colour, or when we look at a thin section of any spine by polarised light. Around the first circle of these solid pillars, we find another layer of the fibro-calcareous net-work, which again is bounded by ano- ther circle of solid pillars, whose transverse sections are seen at c, c, c. The same ar- rangement may be repeated many times, (del, ee). On looking at the outer border of the section, we observe that the rounded sides of these pillars (f,f) form a series of pro- jections with hollows between them ; and these exactly correspond with the projecting ribs and furrows which we may notice run- ning along the natural surface of the spine when we examine this with a magnifying glass, or even (in some instances) with the naked eye. Although there is nothing like interstitial growth in the shell or spines of the Echinus, yet both are progressively enlarged by the addition of new matter. The polygonal plates of which the shell is composed are separated from each other by a membrane that passes into every suture ; and the margins of each plate appear to receive periodical additions, by calcareous deposit in the substance of this membrane. In this manner the globular form of the entire shell is preserved, whilst it undergoes progressive enlargement ; new plates being added, as they may be required, round the anal orifice of the shell (Agassiz). There can be little doubt that the spines are, in like manner, periodically augmented in diameter by suc- cessive formations or acts of growth, which take place in the investing membrane ; and a longitudinal section of the spine makes it evident that these additions not only sur* round the preceding deposits from the base upwards, but pass considerably beyond them, thus adding to the length of the spine. The consequence is, that a transverse section taken near the base of the spine will exhibit all the layers of which it is made up, each layer being narrow, and the central medulla small. A section taken at about the middle of the length may very probably not cut across the original spine nor the older layers, which do not reach so far ; and a section taken across the spine near its apex wi 1 only traverse the one or two layers last formed. Nevertheless, in many species, the spine is larger at that part than near its base ; but the large size is due to the great ex- pansion of the medullary centre, which is composed of a very loose calcareous reti- j culation. The structure of the shell of the Echinus is repeated in that of the three genera which may be regarded as the types of the principal subdivisions of the order Echinida, — namely, Cidaris, C/i/peaster, and Spatangus : there can be no reasonable doubt, therefore, that it is universal throughout the group. The spines, however, of Cidaris, present a marked vari- ation from the plan of structure exhibited in Echinus ; for they are usually nearly cylin- drical in form, destitute of concentric layers, and composed of a calcareous reticulation en- veloped in a cylinder of a solid, apparently homogeneous substance, chiefly calcareous, SHELL. 569 which rises up in ridges upon the exterior. Hence it would appear that, like endogenous trees, whatever additions these spines may receive in length, they can receive little or none in diameter. The slender, almost fila- mentary species of the Spatangaceee, and the innumerable minute hair-like processes at- tached to the shell of the Clypeasteridce, are composed of a like regular reticulated tissue ; many of these are extremely beautiful objects when examined with the microscope without any preparation. It is interesting also to remark, that the same structure presents itself in the Pedicellmice, which are found upon the surface of many Echinida, and which have been so great a source of perplexity to naturalists. The complete conformity which exists between the structure of their skeleton, and that of the animal to which they are attached, would seem to remove all reasonable doubt that they are truly appendages to it ; as their actions also would indicate. The same structure presents itself in the calcareous plates which form the less perfect skeletons of the Asteriadce, and also in their spines, when these (as in the large Goniaster equestris) are furnished with a calcareous frame-work, and are not mere projections of the hard integument. It is also met with in the family Opkiurida, which forms, in some respects, the transition to the Crinoidal group ; but the calcareous skeleton is here generally subordinate to the firm and almost horny integument. In the Crinoidea, on the other hand, the calcareous skeleton is highly developed, and its structure is extremely characteristic. This is well displayed in the recent Pentacrinus Caput Medusa, the stem and branches of which are made up of a calcareous net-work, closely resembling that of the shell of the Echinus. There is ex- hibited, moreover, in a transverse section of the stem of Pentacrinus, as in the spines of Echinus, a certain regular pattern, which results from the varying dimensions of the areolae in different parts. This pattern, formed by the extension of five pairs of rays (strongly reminding us of the medullary rays of plants) from the centre towards the cir- cumference, is frequently well preserved in the fossilized stems of Pentacrini, and varies in different species sufficiently to serve as a distinctive character. In the round-stemmed Encrinites , a transverse section of the joints exhibits a simple concentric arrangement. It only remains for us to notice the order Holoihurida, in which, as is well known, the calcareous skeleton of the other Echinoder- mata is reduced to its most rudimentary con- dition ; never forming a complete and con- nected framework, but only showing itself in detached pieces, the disposition of which is extremely variable. In the typical Hu/o- thuria, there are five solid calcareous plates around the mouth, in which the calcareous reticulation is very characteristically seen. Each of the tentacula, also, has a small cal- careous disk at its extremity, which presents a sort of rude sketch of the beautiful struc- ture of the rosette that supports the ambu- lacral suckers of the Echinus. There can be no reasonable doubt that this peculiar arrangement is universal throughout the group, since it has been detected in cha- racteristic examples of every one of its prin- cipal subdivisions. And, consequently, as no similar calcareous reticulation is found in the internal or external skeleton of any other animal, even the minutest fragment which distinctly presents this structure may be re- ferred with certainty to an Eehinoderm. And this structure is perfectly preserved, even after the substance has been infiltrated with calcareous matter in the act of fossilization, and has become so completely mineralised, that the disposition to rhomboidal fracture makes it difficult to obtain a section in any other direction than that of the plane of cleavage. As already remarked, the elemen- tary structure is essentially the same every- where; so that it might not be possible to determine from a very minute fragment whe- ther it formed part of the shell of an Echinus, Cidaris, or Spatangus, — a portion of the frame- work of an Asterias, Ophiura, or Holothuria, — or entered into the composition of the stem of an Encrinite. But where any regular pat- tern is displayed, this is frequently sufficient to distinguish the genus, or even the species, to which the fragment belonged. This is certainly the case in regard to the spines of Cidarites and the stems of Pentacrinites ; and will probably be found no less true in other instances, when these beautiful structures shall have been more extensively investigated. Crustacea. — The structure of the shell in Crustacea has been hitherto examined only in the Decapod order ; and that of the common crab ( P/atycarcinus pa gurus) alone has been subjected to a minute investigation. It is in the Decapod order that the shell attains its most perfect development, and contains the largest proportion of mineral matter : the special respiratory apparatus in this order being so elaborate as to render unnecessary any participation of the general tegumentary surface in the function of respiration. (See vol. i. p. 752.) The shell of the Decapod Crustacea con- sists of three layers; — namely, 1. a horny epidermic membrane covering the exterior; 2. a cellular or pigmentary stratum ; and 3. a calcareous or tubular substance. The horny epidermic membrane is easily detached from the subjacent layers, after the shell has been immersed for a time in dilute acid ; it is thin but tenacious, presenting no trace of structure, though it may exhibit markings on the under surface, derived from its contact with the cel- lular layer beneath. The pigmentary stratum is very thin in the crab and lobster ; but in some other Decapods it is much thicker. In Scyllurus latus, it is stated by M. Lavalle to be the thickest of the three layers of the shell ; and in the cray-fish and many other species, according to the same observer, it seems made up of a considerable number of layers, its ver- tical section being traversed by several ex- 570 SHELL. tremely fine lines, passing in a direction parallel to the surface of the shell and to each other. The number of these is usually from six to fifteen ; but they sometimes amount to as many as thirty, or even sixty, their number not being in relation either to the thickness of the pigmentary layer, nor to the size of the species observed ; but appearing to augment with age. The cellular layer is that in which the colouring matter of the shell is solely con- tained; but it does not always contain pig- ment, its structure being precisely the same on the white under-surface of the crab as on the reddest portion of its carapace. When examined with a low magnifying power, it pre- sents an areolar aspect ; but when a suffi- ciently thin section is viewed by transmitted light with a high magnifying power, the cha- racter of the net-work, and of the dark spaces it encloses, becomes at once apparent. It is Fig. 425. E.Wiiiiarn $ Cells of pigmentary layer of shell of Crab ; a, papil- lary elevation of subjacent layer. Magnified 400 diameters. then obvious that the nearly colourless poly- gonal reticulations are the thickened walls of cells, each of them being divided by a distinct line, which marks the junction of the conti- guous boundaries ; whilst the dark spaces or areolas are the cavities of the cells, filled with colouring matter, or with some other semi- opaque substance. This cellular layer is not uniformly disposed over the entire surface of the crab-shell ; for the calcareous layer beneath rises up through it in little papillary eleva- tions ( Jig. 425. «), to the summit of which the epidermis adheres. It is from the deficiency of the pigmentary layer at these points, that the shell derives its minutely speckled appear- ance. The internal layer is that which constitutes by far the thickest part of the shell of the crab, and which must be regarded as its fun- damental or essential element, since (according to M. Lavalle) it is never wanting in the Decapod Crustacea, whilst other layers are sometimes deficient. It is in this internal layer, that the calcareous matter is chiefly de- posited ; but even after this has been re- moved, a very distinct animal basis is left. possessing considerable firmness, and closely resembling that which is left after the decal- cification of dentine. When a thin section of it is made parallel to its surface, and sub- jected to a high magnifying power, it is seen to be composed of an apparently homogeneous substance, studded with minute points, each surrounded by a clear space, which correspond with those seen in a section of dentine cut at right angles to the course of its tubuli, and which would seem to possess the same essen- tial character with them. A thin section of the shell taken in the opposite direction (i. e. from surface to surface) leaves no doubt, when examined with a sufficient magnifying power, of the nature of these markings ; for they are then clearly seen to be the orifices of tubuli, which pass with great regularity from one surface of the shell to the other, lying nearly parallel to each other, and having their usually straight course interrupted at tolerably regular intervals by minute sinttosi- Fig. 426. &W'tka>mhs Portion of transverse section from claw of Crab. Magnified 400 diameters. ties resembling the “ secondary curvatures ” described by Prof. Owen in the dentinal tubuli. These sinuosities correspond with bands which are seen to traverse the section, running parallel to the surfaces of the shell ; and they appear, like those of dentine, to indicate the successive stages of calcification of the animal basis. This structure is par- ticularly well seen in the black extremities of the claws of the common crab, in which the intertubular substance is quite transparent in a thin section, and of which the hardness and density are as great as in many varieties oi dentine ; and as the tubuli are seen, in a transverse section of the claw, to radiate from the central cavity towards the surface, the resemblance to a section of a tooth is alto- gether so close, as quite to deceive an ob- server unacquainted with the substance he is examining. The same structure exists, how- ever, in the remainder of the shell; but from some difference in its molecular constitution, the intertubular substance has a less dense and tenacious character, and has an opaque chalky aspect, which renders even a very thin 571 SHOULDER JOINT — (Normal Anatomy). section of it impermeable to light, unless it be saturated with Canada balsam, which then very commonly enters the tubuli, and prevents them from being readily distinguishable. The purpose of the extraordinary density possessed by the extremities of the claws, is evidently to adapt them to the various mechanical uses to which the animal applies them : and it is in- teresting to see that this is attained without any variation in the organic structure of the part, but merely by a more intimate union, as it would seem, of the solidifying mineral matter with the organic basis. It does not seem improbable that the phosphate of lime which is known to be present with the carbo- nate in the shells of Crustacea, may exist in larger proportion towards the extremities of the claws than in other parts of the shell ; a question well worthy of chemical investigation. The periodical exuviation of the shell does not appear to be common to all Crustacea; for, according to Mr. Couch*, it does not take place in many of the sessile-eyed tribes, whose cases are as dense as those of the pe- dunculate orders. It is much to be desired that careful observations should be made on the formation of the new shell in the Crab ; since these would probably throw light on much that still remains obscure in the de- velopment of dentine. [The author of the forgoing article is de- sirous that it should be understood that all the statements contained in it, except such as are expressly made on the authority of others, are the result of his own observations ; the general facts regarding the organic structure of the shells of Mollusca, Echinodermata, and Crustacea, having been determined by him in the year 1842, and embodied in a paper read before the Royal Society, Dec. 22 of that year, of which the first of the memoirs cited is an abridgment ; and the subject having been subsequently worked out by him in de- tad, with the aid and encouragement of the British Association, to the reports of which he would refer the reader who may desire additional information as to the results of his researches.] Bibliography. — Carpenter, On the Microscopic Structure of Shells, in Annals of Natural History, Dec. 1843 ; and in Reports of British Association for 1844 and 1847. Bowerbank, On the Structure of the Shells of Molluscous and Conchiferous Ani- mals, in Transact, of Microscopical Society, vol. i. London, 1844. G. Valentin, Anatomie du Genre Echinus, in Monographies d’Echinodermes vivans et fossiles, par L. Agassiz : Neufchatel, 1842. Lavalle, Re'ehcrches d’Anatomie Microscopique sur le test des Crastaces De'capodes ; in Annales des Sciences Naturelles, Juin, 1847. ( IV. B. Carpenter.') SHOLTLDER JOINT (Normal Ana- tomy of). j- The scapular and the axillary regions are each limited externally by the * Report of Cornwall Polytechnic Society, 1843. t This article includes the surgical anatomy of the scapulo-humeral articulation. region of the shoulder-joint ; the latter also unites the two former regions to each other. The region of the shoulder joint (le moignon de Vepaule ) exhibits a rounded projection, due to the angle formed by the union of the arm with the shoulder ; and to the surgical anatomist it possesses extreme interest, be- cause its skeleton is formed by the shoulder- joint. Some difficulty arises in assigning to this surgical region precise limits. Anteriorly, it is separated from the pectoral region, by the narrow space between the deltoid and the great pectoral muscles (the coraco-deltoid groove, Velpeau) ; above, it is limited by the convex projection of the acromion pro- cess, and by the outer end of the clavicle; posteriorly, it is confounded with the scapular region ; whilst inferiorly, it extends as far as the insertion of the folds of the axilla. The elements of which this region is com- posed, are the following : under the super- ficial coverings lie the deltoid muscle (the greater portion of which belongs exclusively to this space), and in it and beneath it, the branches of the circumflex arteries, and of the great circumflex nerve ; still deeper are situ- ated the exterior of the capsule of the shoulder- joint, the neck and tuberosities of the humerus, the acromion and coracoid processes, with the attachment to them of numerous muscles and ligaments. In this article it is proposed to notice, first, the structures in the scapulo-humeral region which are superficial to the joint ; and, se- condly, to describe the anatomical characters oi the shoulder joint itself. In removing the integuments and subcuta- neous layer of areolar tissue which covers the deltoid muscle, the anatomist brings into view numerous small branches of nerves from the cervical plexus ( supra-acromial twigs), some of the fibres of origin of the platysma myoides, and some small venous branches which, after anastomosing freely with one another, termi- nate in the cephalic or axillary trunks. By the removal of its investing fascia, the deltoid muscle is next exposed : in its origin it corresponds accurately to the insertion of the trapezius ; hence these two muscles are direct antagonists of each other. The fibres of the deltoid muscle arise from the anterior edge of the outer third of the clavicle and of the acromion process, and from the lower margin of the spine of the scapula : from this extensive line of origin, the fibres in descending con- verge to the humerus, and are inserted on the outer aspect of that bone into a rough surface called the deltoid impression. The insertion of the muscle is outside the limits of the scapulo-humeral region, and belongs to that of the arm, whilst its posterior portion is contained in the scapular region; so that the anterior, upper, and central portions of the deltoid alone belong to the region under con- sideration. Immediately beneath the clavicle, the anterior edge of the deltoid is separated from the pectoralis major by a triangular in- terval, of which the base, placed superiorly. 572 SHOULDER. JOINT — (Normal Anatomy). is formed by the bone, whilst the edges are constituted by the adjacent muscles ; in- feriorly, the interstice becoming smaller de- generates into a groove, which continues to separate the muscles from each other, until at length the clavicular fibres of the great pectoral unite with the deltoid, and are in- serted conjointly with it into the humerus. In this muscular interstice the cephalic vein is lodged, which, ascending to the triangular space below the clavicle, there dips into the axilla, and joins the axillary vein. The descending branch of the thoracica acro- mialis ( arteria thoracica lmmcraria ) descends in the same groove, twisting in a spiral manner around the cephalic vein. More deeply still the ligamentum hicorne, enclos- ing between its layers the subclavius muscle, may be seen. The axillary vein and artery, brachial plexus of nerves, and inferior to these and crossing before them, the lesser pectoral muscle, may also be made apparent in this space ; but to bring these latter parts into view, the anatomist must first freely separate the muscles from each other. It has been proposed by Hodgson, in order to place a ligature around the axillary artery in the first stage, to cut between the pectoral and deltoid muscles, and then to separate the clavicular attachment of the great pectoral to an extent sufficient for insulating and tying the artery. As in other radiated muscles, the tendinous structure of the deltoid is chiefly placed in its interior ; as many as three or four laminae attached to the bone above, penetrate into the substance of the muscle, and multiply the points of origin of its fleshy fibres. The fasciculi, of which the deltoid muscle is com- posed, like those of the glutaeus maximus, which is its analogue in the lower extremity, are remarkably coarse and large. When the deltoid is cut across and reflected, the following parts are found in relation with its deep surface ; anteriorly is seen the cora- coid process and the insertions of the pectora- lis minor, of the coraco-brachialis, and of the short head of the biceps into its inner edge, and of the ligamentum bicorne (coraco-clavi- cular ligament) into its summit ; external to the coracoid process is a triangular space, the sides constituted by the opposed edges of the coracoid and acromion processes, the apex placed superiorly at the clavicle, the base inferiorly formed by the convex promi- nence of the head of the humerus ; this space, filled by the coraco-acromial or triangular ligament, should be familiar to the surgeon, as the point of the knife must be here introduced when disarticulation at the shoulder-joint is being performed after the method of MM. Champesme and Lisfranc. Immediately be- neath the coraco-acromial triangle the capsular ligament is situated, and a large bursa (sub- deltoid) which intervenes between it and the deep surface of the deltoid muscle ; still lower down, the insertions of the capsular muscles into the tuberosities of the humerus, also the neck of the humerus, and the bicipital groove, present themselves. The bicipital groove looks directly forwards and lodges the long tendon of the biceps ; into its anterior edge the tendon of the pectoralis major is inserted, whilst those of the latissimus dorsi and teres major take attachment to the very bottom of the groove, passing a little below the level of the former. The anastomosis of the circum- flex arteries, and the circumflex nerve in a great part of its course, constitute also re- markable relations to the deltoid, separating it from the neck of the humerus ; and under the posterior division of the muscle are placed the infra-spinatus, teretes and latissimus dorsi muscles, with the triangular and quadrilateral spaces which they circumscribe. ( Vide Sca- pular Region.) The anterior and the posterior fibres of the deltoid may act independently of each other, and draw the arm forwards and upwards, or backwards and upwards, respectively. The central portion of the muscle is the principal abductor of the upper extremity ; although its insertion is at a considerable distance from the fulcrum, and the power arm of the lever on which it acts is therefore of considerable length, yet the efficient power of the muscle, relatively to its size, is feeble, owing to the fibres whilst in action being invariably parallel to the lever which they are raising. In this action the deltoid is assisted by the supra- spinatus muscle. SCAPLILO-IIUMERAL ARTICULATION. The scapulo-humeral articulation is formed by the contact of the head of the humerus with the glenoid cavity of the scapula. This, the prin- cipal articulation of the upper extremity, is placed at the superior and external portion of the trunk, behind the line of the axis of the hip-joint ; an arrangement which is produc- tive of this advantage, that the most impor- tant motions of the upper extremity (those in the direction forwards) jhave a more exten- sive range than if the articulation had been located nearer to the anterior aspect of the thorax. The arrangement of the articular surfaces and of the ligamentous structures belonging to the shoulder joint, accords with the general plan on which the bones and articulations of the upper extremity are constructed ; “ the disposition and structure of the bones of the upper extremity afford a marked contrast to those of the lower ; the latter are organs or support, and therefore are solid, firm, strong, and withal elastic. The former are destined to perform extended motions, as well as minute and nicely adjusted ones, and there- fore, while they possess all the requisite strength, they are light, present little expanse of surface, and are articulated by numerous very moveable articulations.” ( Todd and Bow- man's Physiological Anatomy, vol. i. p. 147.) The varied uses fulfilled by the upper ex- tremity, added to its remarkable mobility, especially predispose the shoulder joint to accidents; but as we proceed we shall take 573 SHOULDER JOINT — occasion to point out the abundant provisions which exist to counteract this tendency. As regards its motions, and the anatomical dispositions of its connecting media, the shoulder joint belongs to the class of “ Enar- throdial Articulations but, if its bony con- stituents alone be considered, it seems more nearly allied to the “ Arthrodia.” This is owing to the imperfect development of the glenoid cavity which is opposed to the head of the humerus. The shoulder joint is constructed after the same plan in all vertebrate animals whose anterior extremities are developed. In this article the several components of the scapulo-humeral articulation shall be de- scribed in the following order: — 1. The Bones. 2. The Structures which facilitate their motions, a. Arti- cular Fibro-Cartilage. b. Articular Cartilage, c. Synovial Membrane. 3. The Connecting Media, a. Passive connecting Media — ■ the Ligaments, b. Active connecting Media — the Muscles ; in connection with the detail of the Mechanical Functions of the joint. 1. Bones. — We shall speak of these briefly, as they have been already described in the article Extremity. The bones which enter into the formation of the shoulder joint are, the head of the hu- merus and the glenoid cavity of the scapula. These opposed surfaces are of very dispro- portionate size, the shallow cavity of the sca- pula not exceeding in dimensions one-third of the head of the humerus. The glenoid cavity is placed at the anterior superior angle of the scapula, below and be- tween the acromion and coracoid processes ; a slight constriction, the neck of the scapula, separates it, together with the coracoid pro- cess, from the body of the scapula ; superiorly, the neck of the scapula traverses the notch in the superior costa of the bone, behind the base of the coracoid process ; inferiorly, it terminates close to the lower extremity of the articular surface. The aspect of the glenoid cavity in the quiescent state of the scapula, is upwards, forwards, and outwards ; it presents 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 diminishes 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 Medical Science, vol. xv„ 1839. (Normal Anatomy). 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 tendon 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 aspect 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 ot 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, but also the tuberosities; for though, doubtless, the line of junction between the upper epiphysis and the shaft 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. j- 2. Structures which 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 deptli of the cavity is somewhat increased. This structure is thickest at its attachment to the bone ; its free edge is very thin ; a section of it made at right angles to the bone gives it a triangular outline. Both its surfaces are lined by sy- novial membrane, which consequently sepa- rates it externally 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 will 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 of the convex head of the humerus * Traite des Maladies Chirurgicales, tom. iv. p. 176. & > f t Essay oil Fractures, &c., p. 203. Dublin, 18J8. SHOULDER JOINT — (Normal Anatomy). 574 than at the circumference ; whilst the reverse is true of the glenoid cavity, the cartilage being there of greater depth at the circum- ference than at the centre. The anatomical disposition of (c.) the synovial membrane, can be more conveniently studied after the ligaments have been examined. 3. Connecting Media. Carpsular ligament. — This is a fibrous expansion which in its general character resembles the capsular ligament of other articulations. The capsule oftheshoulder joint is remarkable for its capaciousness, and consequent laxity — an arrangement which 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 two apertures, of which the lower is by far the larger. 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-spinatus muscle. The capsule possesses considerable strength an- teriorly and above, being there reinforced by a thick bundle of fibres, sometimes 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 proper fibres of the capsule, and are traceable inferiorly to the great tuberosity of the humerus, crossing an- terior to its bicipital groove. Inferiorly, 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 much 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 from 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 which 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 humerus 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 superiorly with the supra-spinatus, and posteriorly with the infra-spinatus and teres minor muscles ; inferiorly, it is con- nected with the scapular origin (long head) of the triceps; whilst anteriorly, 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 motions 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 much 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 from the upper edge of the tendon of the great pectoral muscle, (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 fraenum,” by Winslow. It must be obvious from this description, that the 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 mainly by the tonic contraction of the surrounding muscles (which are placed in the most favourable position to accomplish this important object). Accordingly, in para- lysis of the upper 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, owing probably to a some- what similar condition of parts, spontaneous dislocation of the humerus has been known to occur in the debilitated state of the sys- 575 SHOULDER JOINT - tem 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-humeral ) 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,” described 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 ■ (Normal Anatomy). 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 pit, 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. Synovial membrane. — In its arrangement and general characters, the synovial membrane of the shoulder joint differs in no way front 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 lined the capsule, the synovial 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 beyond 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. 672. 570 SHOULDER JOINT shoulder joint, and as being intended to com- pensate for 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 protec- tatrice, 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 : I. 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-humeral 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 pass- 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 ; whereas, 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 — (Normal Anatomy). 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- lae, 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 pectoralis 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 way and dislocation be effected. More frequently this accident oc- curs w hen the arm is moderately abducted, and the mechanism by 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 oi contact of the elbow with the ground, and the power at the “ folds of the axilla;” the at- ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 57? taclnnent of these muscles at right angles to the lever, anil 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- scapularis 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 this position, whilst on the other hand the com- parative fixity of the scapula when the arm is being abducted, explains in some degree the frequency of dislocation of the humerus down- wards. 5. Circumduction 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 upper 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 shoulder 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 caused by accidental injury; and, thirdly, those which are the result of congenital malformation. Section I. Disease. — 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 morb'd 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.j- 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, * See Hip .Joint, Yol. II. p. 790. t See Yol. III. pp. 49—55 ; Hip Joint; also Yol. 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 paiu 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 off 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 should 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 inflammation 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 elsewhere in this work denominated chronic rheumatic 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. III. p. 54. f See Hand; Hip Joint; Elbow, &e. &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 shoulder joint, which he will now endeavour faithfully to delineate. 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 6igns 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 examining 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 projects (see fig. 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 of 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 plaee ; 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 w ill 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, set. 27, servant, admitted March 8th, 1848, under the writer’s care. She complained of stiff- ness and weakness of her right shoulder; {fig. 427.), and of pain, which 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-,1 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 TIIE SHOULDER JOINT. 579 ever she moves her arm in the slightest de- gree the scapula follows the humerus, so Fie. 427. Case of M. Moore : Articular caries of the right shoulder joint ; second stage of the disease. 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 the 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. 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 foul' years, but that it never swelled much nor became in- flamed, 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 The foregoing ease 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 favourable ; 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 wall 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 possibility 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 pf 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 muscles ; 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, ast. 21, servant, admitted into the Richmond Hospital 25th July, 1847, under the care of Dr. Hutton. She has been now (June, 1848) eleven months fp 2 580 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. In hospital, and her left shoulder joint has in this period gone through all the stages of ■chronic arthritis ; and a process of anchylosis, 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- quently to this fall she felt pain in her left shoulder, but she cannot recollect that the joint swelled or became hot ; on the contrary, 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 progress 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 than 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 jnt|ich more advanced stage, it was equally evident that the length of the affected ex- tremity was 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 ; hut 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 pro- 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. Anatomical 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 I have been also found coated with lymph. I 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 the post-mortem examination of one ABNORMAL CONDITIONS OF TI1E 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 tbem- 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. Hutton’s care.f He stated that about nine months previously he was 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. f The writer is indebted to Dr. Hutton for the notes of this ease. 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 existed, in which were seen the orifices of three or four fistulous canals, which led from 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 abscess. The car- tilages had been entirely removed from the 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 outlineof the glenoid cavity was elon- gated from above downwards, and somewhaf 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 all 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 stagey there were tubercles and tubercular excavations in both lungs. lu 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*. Articti/ar caries of the shoulder in the fourth stage.lf. — Edward Brady, set. 36, a baker, was admitted into the Richmond Hospital, 6th of May, 1828, 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 blisters, &c., he was not really better. On the contrary, “ the patient was much debili- tated, the hectic symptoms had increased, the shoulder was flattened, the motions of the joint were circumscribed within very narrow limits, the acromion was prominent as in axillary 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 eli- cited on rotating the humerus ; the hand is * Vide Hip Joint, Abnormal Condition of, VoL IL p. 7 04. /?>/. 311. f Museum, Richmond 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 known to the editor of this work as well as to the writer. sUght.li/ aedematous, 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-mortem 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 j 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- I thritis, the anatomical characters which belong to each stage respectively ; but we repeat, we are as yet only truly acquainted with those appearances which the post-mortem exami- nations exhibit of the ultimate result of the disease as it has affected the articular fix- 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 1 humerus from the glenoid cavity, anil conse- quent elongation of the upper extremity ol the affected side. This, we conjecture, may be accounted for by 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-1 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 lymph, or purulent mat- ter to a small amount ; but whatever the effusion be, it also will have the effect 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 s.tage 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, t 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 pretend 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. Anchylosis 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, 184-1, 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- natus 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 diploe of the scapula 584. ABNORMAL CONDITIONS OF TILE SHOULDER JOINT. freely communicating with each other, just as we have already noticed as exemplified in complete bony anchylosis of the hip joint {see Vol. II. 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, ast. 24, ap- peared among the extern patients at the Richmond Hospital on Thursday, 8th June, 1848, 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 had 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 die 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 be called upon to execute when the scapulo- humeral joint is in an anchylosed state. Chronic rheumatic arthritis of the shoulder joint. — The shoulder joint issome- 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 person, 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 remains 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. Symptoms. — 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 around 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 may 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 uneasiness. 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. Diagnosis. — This peculiar affection of the shoulder joint, particularly when the history of the case is known, cannot well be con- founded with 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 muscles 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 attempts 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 head 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 result of accident ; but we are of opinion that, as the chronic rheumatic affection is daily becoming better known to the profes- sion than formerly, such errors will no longer be committed, particularly when 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 capsular 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 neck 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 TI1E 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 productions 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 (Jig- 428. a.). Bones.— The head of the humerus assumes a very characteristic appearance as a con- sequence of this peculiar disease, and acquires a form 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- pies 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 (Jig. 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 arthritis : 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 appearance (Jig. 428.). By these vegetations of bone, we are reminded of the analogous appearance which the corona of the head of the femur presents when affected 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 vie 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.f 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. IT .Jig. 317. page 802. •f Sandifort in his fourth volume has given a delineation of the head of the humerus in this case as well as of the scapula the glenoid cavity of which was enlarged very much in the direction downwards, and was surrounded 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 vauit 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 which the shoulder joint has long been the seat of this chronic disease, the acromion process 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 and thrown inwards over the head of the humerus, 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 had 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 much 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 repeatedly remarked, that one of the most constant anatomical observations we had to make in post-mortem examinations of the shoulder joints of those who 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. affected 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 (7%. 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 off 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 museums, 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 the 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 by acci- dent, but absorbed as the result of disease. We 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 ride 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 disease. 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 may 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 says, the external extremity of the clavicle and the neighbouring part of the acromion were in a great part destroyed, &c.* 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 the shoulder ; and 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 un- 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. 589 ABNORMAL CONDITIONS OF is thinner than natural, 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 shoulder, 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 which the man was admitted, he also had an affection of the right shoulder- joint, which presented all the characters at- tributed to the ease 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. THE SHOULDER JOINT. wasted appearance; 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 w-as 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 0%. 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 floeculi, 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. — Chronic rheumatic arthritis. a, line of complete division of the acromion into two portions ; b , coracoid process ; 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 ; f capsule widen- 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 humerus. 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 process was 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 portions 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 investment 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 room, 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, who 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 jorocess 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 ot cartilage. There were also many particles of cartilaginous matter upon the head of the os humeri, and upon the hollow of the new 591 ABNORMAL CONDITIONS C 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 piece of the 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 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 ligament is torn, and the head of the bone has an opportunity of escaping forwards to the coracoid process.” * The foregoing dissection, whicli 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. F THE SHOULDER JOINT. 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- tion 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 shoulder 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 (fig. 4-29.), 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 gratuitously, because the previous history of the case he alludes to was unknown, and the accident supposed 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 {fig. 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 j of Sandi- fort, 1827, we find delineated the bones of the shoulder joint which present all the cha- * See Athenreum, September 10, 1836 ; also Pro- ceedings of the Dublin Pathological Society, Dub- lin Journal, vol. xv. p. 502. | Yol. iv. tab. 24 . figs. 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 (“ luxatio 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, polished, and ivory-like (“ partial porosa sed coatera 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 articulari affert eandem praeternaturalem glabritiem et duritiem, dum in vertici, ubi tuberculuni majus occurrit, superficicm exhibet partim glaberrimam, par- tial inequabilem, rugosam, quae juxta sum- mum humerum movebatur trituratione, etiam locum habuisse inter marginem inferiorem clavicular, et verticem capitis humeri mani- feste apparet ; 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 * Museum Anatomicum Sandifort, tab. cli .figs. 1, 2, 3. vol. iv. had been partial 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 {Jig. 429.). The explanation of the circumstance why the superior 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 poreelainous deposit (Jig. 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 (iO, 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 TIIE SHOULDER JOINT. 593 tion, and the deltoid muscle was cut across anil thrown back, when the attention of the dissector was attracted by 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 appearances 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 defith, showing the degree of ele- vation of the summit of the humerus on the affected side ; and also exhibited a prepara- * This specimen is preserved in the Museum of the College of Surgeous. 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 humerus 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 showed 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 much 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 Q Q ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 694. 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 medium 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 tenclon 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 Sudan's case. — Partial disloca- tion upwards. — “ 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 could 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 beyond 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 j 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 i 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 ? Upon 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 immediate 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” be felt re-assured, and endeavoured to resume his work. It would appear to us, that if the tendon of the bi- ceps were accidentally dislocated the patient would not be able, immediately 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 we 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 analy- 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 told, of a rheumatic habit, or predisposed 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 called 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'ore 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, wbo 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, retat. 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 <1 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 belonging to rheumatic gout, or chronic rheumatic arthritis.* 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. Lie 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 suffering. 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 examination. — 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 I, and could not be extended, but they permitted of flexing to a very trivial degree. When any of the affected joints were moved, the characteristic crepitus, or crackling, 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. Upon 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 Hand. Yol. II. p. 518. fig. 233. capsular ligament, superiorly and posteriorly, was very short, 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 inferiorly the capsule descended on the neck of the humerus below 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 anti 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 head 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 (fig. 430.). The tendon of the biceps lay entirely to the 5 Case of Charles Mailly. — Chronic rheumatic arthritis. The long tendon of the biceps dislocated inwards, the head of the humerus partially displaced up- wards, as in Mr. Soden’s case . . inside of the head of the humerus ; 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 597 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. above the course of the tendon of the biceps was divested of all cartilaginous covering, 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 11s 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 villi, 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 semi-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 ether 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 and its membranous coverings we found the peri- cardium 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 internally, 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 biceps 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 immediate 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- ternal!}', 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 inwards, 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 ■ HQ 3 508 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 tlie 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 right and left shoulder joint of the same individual. Partial dislocation of the head of the humerus inwards. — In the museum of the College of Surgeons, Dublin, we find a specimen pre- sented by Professor Hargrave, which he con- siders one of partial 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 ; hut 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 thehumerus. 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 glenoid 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 apposition 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 slight/// hollowed. 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 ruptured, 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 glenoid 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 theout- 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. The coracoid process, wc 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 E. C. of Surgeons, Dublin, vol. ii. p. 397. Edinburgh Medical and Surgical Journal, for October, 1837. 599 ABNORMAL CONDITIONS arthritis exist in this shoulder joint, but also that the acromio-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 not really afford any proof that exter- nal injury was the cause of the partial luxation. In thus differing from Professor Hargrave, we would make the same remarks which we have already made in allusion to Sir A. Coo- per’s case, at page 591 . of this article. The pro- gress of science will soon settle the question. Partial displacement of the head of the ha- mej'ns downwards 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 effusion into the cavity of the joint, of crepitus having been fedt 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 chronic rheumatic arthritis, shortly to he published by the writer ; illustrated hy lithographic drawings of natural size. OF THE SHOULDER JOINT. example adduced by Sandifort must be con- sidered as the result of chronic rheumatic Fig. 431. Scapula and portion of the clavicle connected to it, viewed externally.* a , glenoid cavity ; h, a fragment of hone 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 “oninem motum clavieulse seque- batur.” (After Sandiford. ) arthritis of long standing, with partial displace- ment of the altered head of the humerus down- wards (fig. 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 ligament 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, we 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 writer 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, which had been affected by this chronic disease, was thrown completely backwards on the dorsum of the scapula. In this case the displacement was double, and two new glenoid cavities had * Diminished drawing from one in Sandifort’s Museum Anatomicum, vol. iv. table 25 .fig. 2. Q Q 4 COO ABNORMAL CONDITIONS OF TIIE 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 vvas 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 around their borders ; 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, are 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 may be 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 ofthe 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 vvii 1 be pulled down by the weight of the extremity and contraction of the deltoid muscle. The portion 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 superior 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 ofthe 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. Thus Boyer f gives us the account of a fracture ofthe 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 j that if the contusion accom- panying this accident be slight, we can seize * Sir A. Cooper, t Maladies Chirurgicales. t Sanson. ' ABNORMAL CONDITIONS OF THE SHOULDER JOINT. C01 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 which 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 line 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. K. Smith has exposed well the error of con- founding together as the same the line of the ana- tomical neck of the humerus, and the line by which the superior epiphysis is united with the shaft of the hone. 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 from the severity of the injuries which accompanied the fracture. He mentions the case of a woman who lived for seven days, alter 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. Re'ichel 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; anti 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. Macdowell, 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 fracture 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 shoulder was care- * Cloquet, Dictionnaire de Medicine, article Frac- ture. G02 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. fully examined. The arm was slightly 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. Upon 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 displaced 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. 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 summit 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- tions, which had sprung up from the shaft of the humerus. In the year 1813, 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, set. 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 ; anti the capsular muscles atrophied. Dissection. — 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 Nelaton’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 anatomical 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 tins complete inversion of the upper frag- ment of the brok n humerus is to be found A ; 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 above 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 J bone is broken into many fragments. There is some shortening of the ai m, 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 ol * See Dr. Ii. Smith’s work on Fractures. Dr. 1!. Smith’s work on Fractures. 603 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 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. Symptoms. — 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. 60, 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 failen 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 ol 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 spiculae of the broken humerus, and this membrane showed decided traces of having been the seat of inflammatory action. The cartilaginous covering 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 accident. 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 for, 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 line of practice was pursued. 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 through the line of junction of the epi- 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 below this line in the surgical neck, occurs, then much displacement of the frag- ments may generally be observed. Sir A. Cooper has described an assemblage cot ABNORMAL CONDITIONS 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 in 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 extension, 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 by 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 aet. 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 immediate 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 of 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 (fig. 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-clavieular 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 engaged in the deeper layers 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 humerus 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- diately 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, 1848, fell from a height of seven feet off a ladder, and was thrown on the posterior part of his left shoulder on uneven grounj. He was not seen until next morning, when the injured shoulder presented the following appearances * : — “ There was a i 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 abducted, but it could be readily pressed against the side. He could 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 Mr. 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 eond) le 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 nth. — 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 6th 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 necle 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 by the principal part of the shaft of the humerus, is drawn upwards 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 process 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 the 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 frequently 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 posi- 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 60C 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. 1. — 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 pec t oralis 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, the 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 downwards 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. Symptoms. — 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 (fg. 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 communicated 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, anil to raise it up to the head, and even press the elbow close to the side. On moving the limb, a slight crepitus 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 immediately 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 thei 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 wTas 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 below the centre of the glenoid cavity from which it had been thrown. The 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 supra-spinatus. 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- spinatus muscle my great opponent, until 1 drew the arm directly upwards, when the head of the bone glided into the glenoid cavity. The deltoid and supra-spinatus 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 satisfactory 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 wrho 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 pushed upwards, and detached from the inner surface of the scapula {fig- 434.). Fig. 434. Axillary 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 the head of the bone, and interpose themselves between it. ami 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 snpra-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 apparently similar dislocations of the humerus, there may be very different kinds 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, th e cellular 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 Mr. Thompson’s case, the capsular ligament was completely 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 Astley Cooper’s cases, on the contrary, although the tendon of the subscapularis was torn through, the supra- and infra-spinatus muscles retained the connection with the greater tubercle, and “ until this muscle was relaxed, by raising the arm, the humerus could not be reduced by any efforts which 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. C09 the head of the bone is found altered in its form, the surface towards the scapula being flattened, a complete capsular ligament en- Fig. 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, like 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 bead 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 himself 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 Jig. 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. the longitudinal axis of the limb passing from below upwards, is much altered, being thrown Fig. 436. 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 Philip 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 immediate neighbourhood of the Meath Hospital, while the lime was still burning ; he was drawn up by ropes, but just as he reached the top of the shaft, the rope broke, and he again fell to the bottom, a dis- tance of about fifteen feet, on the ignited stones. It appeared, on examination, made in theMeaih 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 dislocation, 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 R R CIO ABNORMAL CONDITIONS 0 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 ot 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 downwards, so that they formed a curve, which partly embraced the neck of the humerus (fig • 437.). The supra- and infra-spinatus mus- cles were on the stretch, but had suffered no injury. The cellular substance covet- 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. A 37. Dislocation forwards and inwards. ( Sir P. Cramp- ton's 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 humeri, 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 F THE SHOULDER JOINT. 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 forwards set- tles the long disputed question as to whether or not the humerus can be dislocated primi- tively in any other direction than downwards, 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 forseven 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 scapulae, 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 jj its attachment to the venter. The head was situated on the inner side of the coracoid 1 process, and immediately under the edge of the clavicle, without having the slightest con- neetion with the ribs; 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 hands 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 (Jig- 438.) is taken from a scapula preserved in the museum of the College of Surgeons in Dublin, and re- 611 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. sembles much the specimen alluded to by Mr. Key. The newly formed socket reached from Fig. 438. the edge of the glenoid cavity, to about one- third across the subscapular fossa ; a deep cup was formed for 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 scapula. 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 we look at the shoulder side- ways, the head of the humerus may be seen to form a remarkable 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 immediately 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. Complin 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 stragglings 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-mortem, proved that the cause of' this symptom was the laceration of the tendon of the subscapularis muscle, which was found to adhere 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 but 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 anti relaxed, as the head 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 which 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 the acromion was sawn off, to look for any little fragment 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 I 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 forepart 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 scapula;. The elbow cotdd 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 limb giving him 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 injury becomes very evident indeed. A gentle- man, Mr. A. F., aged about 35 years, called upon the writer four years ago to examine his shoulder. He stated that he was thrown off a jaunting car about three months previously, and injured his shoulder, and that ever since he had had but very imperfect 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 oj the humerus backwards on the dorsum of the scapula. about ten weeks after the accident, he called upon the writer. The 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 (Jig. 440.). Tills 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 (fig- 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-bumeral 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 different 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 falling, his arm is se- jparated from his body directed forwards, or outwards, as it were instinctively to break .he fall, and save the upper part of the body, f under these circumstances displacement of he upper part of the humerus occurs, the existing deformity will be found to be the 'esuit of dislocation; but if, on the contrary, he fall takes place when the arm is by the fide, as, for instance, in the breeches pocket, md no effort is made by the patient, at the 'noment of the fall, to raise the arm, the nomentum and weight of the body have been eceived on the point of the shoulder, the esulting injury has been most probably a racture of the head and upper part of the mmerus. In both cases the pain expe- ienced 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 observable 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 twro 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 seizing 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 l’epaule deformee, soyez as- sure quevous 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 ordinal-}' 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 almost 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 limb 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 with 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 muscles, 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 Philip 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, hut 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 similar 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. When 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, but 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 ; i 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-t 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 much obscured by the effusion of blood, and by the inflammation which speedily follows ; but, for the first three] hours, the muscles are so lax, that but for the] pain it occasions, considerable motions ot thij limb might be produced. * Medical Obs. and Enq. vol. ii. p. 349. * Smith on Fractures. 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, “ 1 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 Cliirurgicale, Paris, tom. 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 eedematous 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 inflammation. 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 ail 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 R. C. Surgeons, England, vol, ii. p. 20. No. 868. ER 1 616 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. and it is known that Desault had already ob- served a similar occurrence. A Memoir, con- taining six cases published in the Repertoire d’Anatomie 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 cases 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 inflammation 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 Lemons 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 tons 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.” * Alterations of the nerves. — 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 symptoms. The nerves, besides being stretched, have been sometimes even torn across; when this has oc- cured the effects produced must long 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 circum- flex 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 circumflex 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 w'as 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, set. 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 or 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 clinical 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 axilla he immediately concluded could be attributed to no other source than to the laceration of a large artery. He quickly sought for the pulse 1 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 sub< la- vian, while the pulse, though feeble, coulu be readily felt at the heart, and in every externa! 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 of the axillary artery ; in a word, be- sides the dislocation there was a diffused aneurism ; the latter was unattended by any pulsation, so that he conjectured the artery was completely torn across. He did not long deliberate 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 Kouines, 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 the 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 patient 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 aiong 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. Alter 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, but 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 failing, 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 consulta- 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 (fig. 441.). The young lady is now 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 comparing 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 ( fig . 441.). Case. — The following is the history of the case from which the drawing has been taken. M. H., set. 28, is in every respect healthy and well formed, except as to his left shoul- der, which, since his birth, has always been noticed to have been smaller than the other. This defect gives a peculiar appearance to his whole figure as he stands 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 little 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 suffered 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. 618 ABNORMAL CONDITIONS OF THE SHOULDER JOINT. also slightly adducted towards the middle line. When the shoulder is viewed posteriorly a depression corresponding to the situation of the posterior half of the glenoid cavity is observable : into this depression the finger can be sunk so far as to reach the surface of the posterior part of the glenoid cavity. When the arm is drawn forwards across the chest, the head of the humerus passes backwards beneath the acromion, and a depression can be felt in front beneath the coracoid process, corresponding to the portion of the abnormal articular cavity which the head of the humerus had just before occupied. The muscles of the region of the shoulder are very imperfectly developed, but those of the fore-arm and Fig. 441. Case of 31. Ii. — Congenital malformation of the left shoulder joint, with luxation of the head of the humerus inwards. hand seem of their normal size. The patient has but little power of moving the affected upper extremity. The trapezius muscle of this side is well formed, therefore he can by means of its influence elevate on the side of the trunk the whole limb. The deltoid and capsular muscles are very imperfectly formed, and consequently the patient has no power of abduction, nor of rotation, of the humerus. The shoulder has not the usual rounded form, but still it does not present the flattened ap- pearance, nor the acromion the angular out- line which characterises the accidental luxa- tion of this joint. Yet the acromion process does project somewhat, and when the arm hangs by the side, the head of the humerus, distinct and prominent, is removed so much from the under surface of the acromion, as it were by the weight of the limb, that the thumb can be easily placed between them. When we take hold of the elbow and raise the arm vertically, the joint assumes more of a natural form. Still; independent of its com- parative diminution of size, it wants the ro tundity and fulness of contour ordinarily de- rived from a proper development of muscular covering. The elbow joint is perfect as to its form and functions. This patient has been under the writer’s observation for many years, and these symptoms have not varied. Anatomical characters of congenital malform- ation of the shoulder joint with displace- ment of the head of the humerus inwards. — We may consider the following as a good example, showing the anatomical characters of the congenital malformation of the shoulder joint, with displacement inwards of the head of the humerus ; the congenital defect ex- isted in both shoulder joints. Case.—11 A female, aetat 28, who had been for many years a patient in the lunatic department of the House of Industry, died of chronic is- 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 anatomical 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 was 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. j 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 shoulder joint, 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. 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 already noticed a similar condition of the liga- ments, and a similar effect, when describing a case of congenital malformation of the radio-humeral joint. See Elbow Joint, Yol. 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- pearance 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 expressing his opinion that the case was one of double congenital luxation 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, immediately 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 wras 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 w'as 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 have 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 socket 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. 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. ; Seehster 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 laeerum 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 lies 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 of 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. 621 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 which 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 tentorial 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. A very 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 outwards, 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 tile preceding details. Since anatomy shows that its terminal distribution is exclusively to a muscular surface, we should on this ground alone be tolerably entitled to predicate its motor function. The little that is known of its comparative 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 optic 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 insensibility 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 Nerveux. 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. Bibliography. — See “ Nerve.” ( William Brinton .) SKELETON. — The name skeleton, o-yt- \erov, formed from cryfXXo.), 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, l 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 unity 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 j" three thousand years back, and afterwards lay in cold obstruction till resumed in later times by Leibnitz, Newton, Buffon, Cuvier, Geoffroy St. Hilaire, Oken, Goethe, Cams, 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 j beings more or less closely to one another. His || “ loi de continuity ” is founded likewise upon the I same general fact. He defines the universe as “ l’unitd dans la varie'te',” and of the animal king- dom he writes, “ tout va par degres dans la nature, et rien par saut.” See CEuvres Pliilosophiques de M. de Leibnits, liv. p. 440. f Aristotle, the great founder of generalisation in the physical sciences, was strongly impressed Ij with the common resemblances or analogies of ani- mals, and expresses the fact as follows: — “hut , some animals neither have parts specifically the same, nor the same according to excess and defect, j but according to analogy.” History of Animals, |J book i. p. 4. trans. by. Taylor. J The late work of the learned Hunterian profes- sor, entitled “ Homologies of the Vertebrate Skele- ton,” contains, in addition to his own especial views, a complete account of all that has been written upon the subject of skeletal analogies by the leading com- SKELETON. 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 assayed 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 1 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 with greater freedom and less confusion than perhaps we do.” Locke, Reality of Knowledge. 623 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 unmistakeable evidences of an en- chained specific diversity, the latter encountering the former condition at every step of inquiry, and neither the differences nor the analogies (while contem- plated as such under the same regard) holding forth to me any 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 whole form — some integer or full skeletal figure which might be seen as containing in its own quantitative character the sum of all known 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 Archetype 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 dtendue, sont les rapports necessaires qui derivent de la C24 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 similitude 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, while 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. Vcrtebi ee 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 ,fig. nature ties choses.” Esprit des Lois, lib. i. ch. 1. Montesquieu. * Lamarck originated the name vertebrated, as characterising one great division of the animal kingdom, — “ Les animaux verthbres,” from the other “ Les animaux sans vertfebres.” But comparative osteology, as studied in the present time, has almost rendered this name obsolete, incapable, as it evi- dently is, to be the instrument wherewith 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 dejk montrd qu’il est un produit de l’art, et que rnalgre' les apparences contraires il ne tient reellement rien de la nature.” See Philosophie Zoologique, tom. i. chap. v. f 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 which we see apparent in the proportionals of a whole quantity ; thus a segment of a circle or a semicircle, 4 1 1.) differs in this respect from the dorsal ver- tebra (c) ; this from the lumbar vertebra (e); Fig. 444. Vertebra of the human spine, Showing a quantitative difference. The similar parts of each bear the same figures. this from the sacral vertebra (ii); and this from the coccygeal vertebra (i). In all ani- mal spinal axes 1 see that those bodies which the comparative anatomist names vertebras 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 vertebra; 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- p tional correspondence ail three; and in the same way, vertebral quantities which manifest to each p other a similar degree of proportional correspond- ence, seem to point to some unknown whole quail- 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, which, 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 firm basis of demonstrative evidence. SKELETON. 625 the human cervix, thorax, or loins, or sacrum, or caudex, the vertebrae 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 surplus rib (j%.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 vertebra 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. Even 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, fig. 444.) of the mammal spinal axis occasion- ally produces a costal appendage (4 of b). The first lumbar vertebra if, fig. 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 vertebra; contain a greater or lesser amount of certain Icnown elemental qneces. — 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 ff vertebrae (whatever be their special \ariety) jtontaining few or more of those elemental luclei from which vertebrae are fashioned. Thus as we find vertebrae to be constituted from i whole sum of elementary pieces proper alone o vertebral form, we therefore consent to give he name vertebra to every spinal figure which hall produce any one element proper to the leal vertebral type. But then we must not Understand by this name vertebrated, a coii- ition of absolute quantitative uniformity* * The uniformity of a serial line of bodies im- lies that all units of the line of serial order ire quantitatively equal and homologous. A series circles would constitute such an uniformity, (ecause all such circles would be similar. Uni- irmity, taken in this sense of equality among the pits of the series, does not characterise the verte- "al spinal series ; but while we see that vertebrae, ough not uniform as quantities, are still various dy as proportionals of a greater ens or archetype, en 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 endo- 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, _/£§■. 444.) is only different from a lumbar (f,e) or cervical vertebra (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 ,fig. 444 ) is in reality a vertebral centrum (5) 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 plus in those very same elements which the coccygeal vertebra wants. It is sufficient for us at pre- sent to know clearly that all vertebras 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, fig. 444.), being as a vertebral centrum (5) 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 human anatomist separates the dorsal vertebra (c, fig. 444.) from its costal appendages marked din 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, while 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 differential quantity which is to equate it with a +6; and this is the mode which I adopt, in order to re-establish the original typical uniformity of skeleton bodies, for I shall p'rove that the known quantitative difference be- tween two unequal forms renders them equal in idea. The typical skeleton of Cams 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 forrh, regardless of the difference as to function. The paramount necessity of this will at once occur to the reader, and he will recognise in the truly philosophical researches of the Hunterian professor an advance towards the truthful interpretation of the law of formation, equal in degree to the measure of this mode of comparison adopted by him. s s SKELETON. 626 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, Jig. 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. transverse process (4, 3, fig. 445. b), is the true homologue of the thoracic rib (4 ,Jig. 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 an thropotomist 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 ah exeellentia functionum et remediorum sequentium non eurantur.” Novum Organon Sci- entiarum, Aph. 30. shall lay down my remarks as follow : — I se- parate from the human spinal axis that body (c.Ji'g. 444.) which the human anatomist terms the “ dorsal vertebra ; ” and on comparing it with the cervical vertebra (a ,fig. 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 ,Jig. 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 vertebrae (a, c. Jig. 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 vertebrae that a doubt arises as to their identity. Now if I call the posterior moiety (3) of the transverse process of Jig. 445. b, the true homologue or counterpart of the dorsal transverse process (Jig. 444. c, 3), I still have no element in the dorsal ver- tebra (Jig. 444. c), wherewith to compare the anterior half (4) of the cervical transverse process of Jig. 445. b. But when I apply the costal piece (4 ,Jig. 445. a) to the dorsal vertebra, constituted of the pieces 1, 2, 3, 5, then it becomes evident that this costa ;s supplying the place of the anterior half (4) of the cervical transverse process (fig. 445.). * All 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 he fully acknowledged, still so difficult was it for them to emancipate themselves from tiieli 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-;1 ably with the artificial vertebral quantity of the human anatomist’s “ dorsal vertebra,” whose trans- verse process is single, that of the cervical veitebn being double, both processes were held to com spom nevertheless; and consequently, when such a fac as that of the anterior nucleus of the cervical trans verse process being produced to the dimension o a cervical rib appeared, they, with Meckel, inter preted this as a prolongation of the cervical trans verse process, which they had already regarded a homologous with the process so named in the dorsal vertebra: or with Blainville, they acknowledge!! its costal character and proportions, but interprete it as belonging to a “ category of ribs proper t themselves,” distinct from those of the thorax, an also diverse to those called “ cervical ribs” in olhi classes of animals. And although it had beej broadly asserted, long since, by Hunauld, Sardj fort, and others, that the transcendental law gay to even the human skeleton more than twelve pai of ribs — the supemumei'ary ones which now ant then stood upon the cervical and lumbar vertebra- still, owing to the obstructiveness of the pre-coi ceived doctrine of the mammal cervix being ad counted limited to the number of seven rible vertebrae, even nature herself failed to prove tl invalidity of that general rule, though she present* them with the sloth’s cervix, which produces nil ■§ vertebrae, and that of the human species occasional ■ producing only five or six. IjH 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, 1,5) 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 {Jig. 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 Jig. 445. b, is the true counterpart of the tho- racic rib {fig. 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) ot the cervical transverse process {fig. 445. b) and the dorsal transverse pro- cess {fig. 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 {fig. 445. b) possesses a costal element (4), just as the dorsal vertebra (y%.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 vertehrce 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 vertebra;, 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- ween the cervical vertebrae, even that named itlas {fig. 446.), and the thoracic costo-ver- Fig. 446. ebral quantities {Jig. 444.) is one of quantity ; nd this difference in quantity appears upon miparison to be alone attaching to the costal This term, “neural arch,” is used by Professor Wen, from whom the term originates. “ By neural arch, I mean both neurapophysis and ' ural sP'ne, or the totality of the distinct parts of nch such arch is composed.” Homologies of the ertebrate Skeleton, p. 190. appendages marked 4. — The thoracic cost® are of larger dimensions titan the cervical costa;. 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 (e, 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, Jig. 444.) which has never been seen separate from its ribs, as it appears in T>,Jig. 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 (b ,Jig. 447.) with the last costo-vertebral tho- Fig. 447. racic form {a, fig. 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 s s 2 C28 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, fig. 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 ” f so called are also counterparts. The lumbar vertebra therefore produces the costal appendage.j Prop. VIII. All the lumbar vertebra? 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 difference. — The ribs of the thorax are proportionably larger than those of the loins. In the thorax the costae (4 of a, fig. 447.) appear articularly connected with the centrum (5). In the loins the costa; (4ofc, fig. 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. f Cruveilhier states, as a peeuliarity.of the lumbar transverse process, that it sometimes remains arti- cularly separate, and simulates the costal character, becoming the “ supernumerary rib.” Meckel alludes to the fact also. J On referring to the “ Homologies of the Verte- brate Skeleton,” I find the following affinnation ; — “ Each of the five succeeding segments is repre- sented by the same elements (centrum and neural arch) coalesced, that constitute the so called dorsal vertebra ; they are called ‘ lumbar vertebra: ; ’ they have no ossified pleurapophyses.” 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 process as being the counterpart or homologue of the dorsal transverse process, which, if such were the case, would leave the lumbar ver- tebra without a rib. vertebrae, then the elements (4) are as ribs seen in f ,fig. 444. Prop. IX. The sacral vertebrae 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 vertebra?, then we may account both lumbar and sacral vertebra? as homologous with the costo-vertebral tho- racic form. And it does appear that the sa- cral vertebra (n,fig. 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 (is, fig. 447.) and of the costa (4) of the thoracic form (a] fig. 448.) and of the anterior half of the cervical transverse process (4, fig. 445.). All these pieces hold serial order ; all are autogenou growths ; all are posited in the same relatioij witl) respect to the other vertebral piece (1, 2, 3, 5) of the cervical, dorsal, and lumba forms. Now', having once determined th proper identity of the anterior nucleus (4) < the lateral mass (3, 4) of the sacral vertebi (a, fig. 448.), it becomes easy to recognise th; homological cast and relation of all the oth< pieces of the sacral vertebra. The posterk half (3) of the lateral mass of the sacral vej1 tebra (b) is the counterpart of the “ tubercle (3) of the lumbar vertebra (n,j?g.447.),of tl transverse process (3) of the dorsal verteb (a, fig. 448.), and of the posterior hah' of tl transverse process (3) of the cervical verteb (fig. 445.). The spinous process (1), larair (2, 2), centrum, or body (5) of the saci vertebra (b, fig. 448.) are evidently identii with the like-named parts of all the otl vertebra? correspondingly numbered. It " hence appear that sacral vertebra? do r differ from other vertebrae ; and that it is error as to the identity of the anterior nuclu SKELETON. 629 (4) of the lateral mass of the sacral vertebra (b,7%. 448.), which causes the human anatomist to name this anterior nucleary appendage as the “ peculiarity ” of sacral form. This anterior nueieus of the sacral lateral mass, I call a rudimentary rib abutting against the iliac bone. Prop. X. The coccygeal vertebra: are de- prived of their costal appendages. — The serial order in which we find all spinal figures standing, renders it, under comparison, a de- monstrable fact, that the coccygeal bones (b ,fig. 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 though 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 vertebra of the spinal series, j et 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 vertebrae, 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, fig. 449.) is equal to A, or to any ocher 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 tad subtracted from them their spinous (1), leural (2), and costal elements (4); and un- ler this interpretation we nay have as strong m idea of the whole or plus quantity (a) of vhich caudal bones (b) have been metamor- phosed, as ii we saw those quantities still per- isting entire. The difference between any of he costo-vertebral spinal segments and a caudal bone is like the quantitative difference between a -\-b and a — b. Thus a, fig. 449., minus the elements 1, 2, 3, 4, equals b ; while b plus the elements 1, 2, 3, 4, equals a. Prop. XI. The first seven thoracic costo- vertebral figures are whole or plus quantities. — In no one respect do the first seven thoracic costo-vertebral figures (all equal to fig. 450 J differ from each other; in each of them may be counted the same elemental pieces ; and those pieces of each (marked as inj»%.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, the whole quantities (such as fig. 450.), 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, because 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, 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 far 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^g. 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- s 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 plus or whole quantities would then be the variable proportionals of such plus figures; and, being proportionals, would therefore be proportionally, 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 Jig. 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- bral 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 typical 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 pi'ove 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 vertebra; what- ever, then must it be evident that the simple costo- vertebral quantity, as I have drawn it, is all-suffi- cient as the archetypal whole composed (dorsad) of a neural arch and spine, and (ventrad) of a haemal 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 archetype or plus figure. Neither will it be required for my typi- cal spinal figure that I should introduce into its proportions the parts called haemal arch and spine (the chevron bones) as things distinct from the ventral costal circles (thepleurapophyses),whileIsee 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 sum of his ty- pical form, to be in reality but varying 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 sternal costo-vertebral plus quanti- ties.— The thoracic region ofthehuman 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, Jig. 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, Jig. 451.) becomes the advent or presence of the specific difference be- tween Jigs. 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-j 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 Jig. 451. Prop. XIII. The five lumbar vertebra, are proportionals metamorphosed from fine sternal costo-vertebral archetypes. — The se- ven sternal costo-vertebral circles are sue-! ceeded by the five asternal costo-vertebral proportionals, and these latter by the five- lumbar vertebrae. In this series of spina'; 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 costa1 elements only. In all other respects th. lumbar and thoracic segments are similar for in both orders of structures we find tin same elements, such as spinous processes: transverse processes (the tubercle being th; transverse process of the lumbar vertebra) centra, and neural arches. In both we alsli find the costal appendages, but these are no of equal growth or quantity. It is quit true, however, that the sternal costa is serial! succeeded by the asternal costa, and this bJ 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 outline for Jig. 4-52., for it is true Fig. 452. ca that the presential proportional condition of lumbar vertebrae, consisting of the elements 1, 2, 3, 4, 5, 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 vertebra 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 iumbar 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. Fig. 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 j quantity, the complement of which I have drawn as the parts marked 1, 2, 3, 4, 6 I around 5, Jig. 452., thereby equating it with the plus thoracic form. Prop. XV. The seven cervical vertebra; are proportionals degraded from seven sterno- costo-vertebral whole quantities. — The same elemental quantit}' which is proper to a lumbar vertebra is to be found in a cervical vertebra. In both (vide Jigs. 445. and 447.) we distinguish the centrum (5), the neural arch (2), the spinous (1), and transverse pro- cesses (3), and the costal rudiments (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 dep>ends upon proportioning 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. 455., 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 oflumbar 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. Tn 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 figure 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 632 SKELETON. and sternum drawn at neck and loins, as well neck and loins, than to understand her as as thorax, degrades this prime-model to the having first given creation to an ens of dimensions of a specific or proportional lesser proportions (such as fig. 455.), with variety, by obliterating costal quantity at the cervical and lumbar vertebrae lesser than Fig. 455. Showing in dotted outline at the neck and loins those 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, viz. 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 segments of the spinal axis, created, as it were by after thought, other figures secondary 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, Caras expresses his idea of the organic whole quantity compared with the lesser thing or species : — “La partie d’un tout organique est incontestablement doude d’un organisation d’au- tant plus elevde qu’elle repete plus parfaitement en elle l’ide'e du tout, et le tout lui-meme est d’autant plus parfait qu’il correspond d’avantage a l’idde de la nature entihre dont nous ddvons reconnaitre que 1’essence est l’unite des lois dternelles reveldes dans l’infinie diversity de la manifestation.” See C. G. Caras, Traite Element. d’Anatomie Comp. c. xi. p. 26., traduit par J. L. Jourdan; see also Cams, Yon den Urtheilen des Knocheu und Schalengerustes, fol. Leipzic, 1828. these by the addition of new and unknown elemental structure, such as a thoracic rib anti 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. XVII. Uniformity of structure is a condition proper to the plus thoracic origi- 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 from 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 bv the centrum (5 ,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 {5,, fig. 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,)1 ns 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 Jig. 455., whose serial units at neck and loins are equated with the thoracic lin ts, 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 their own originals, such as those of the thorax , and hence 1 conclude that uniformity alone characterises the series of such originals. f Prop. XVIII. Every spinal segment which is lesser, refers to every spinal segment which is greater ; and all lesser segments refer to that which is greatest.- — If it be easy to conceive that the last caudal bone (i,J%.444.) is a lesser quan- tity metamorphosed from such another quantity as the penultimate caudal bone (11, Jig. 141.), where can be the difficulty in rationally inter- preting both to be as quantities metamor- phosed or proportioned from such quantities as lumbar vertebrae (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 Jig. 450. ; or if it were not the fact 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.): 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 which those proportionals themselves repre- j sent are likewise infinite. “ Species autem ilia ab- i 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 ’ we contrast with this quantitative uniform line this i other line of graduated proportional serial quantities, i such as the present state of the mammal skeletal axis exhibits them, we are enabled to estimate the j law which has created the line of proportional quan- j tities such as we find it. When the special or pro- portional thing is contrasted with the uniform whole ' or complete quantity, the contrast gives the inter- pretation. If species arise from the infinite sub- j division of the line of whole quantities, then this latter, as perfect quantitative uniformity, may be I defined as follows : — “ Unitas (uniformitas) est sine jeommissura (sine liiatu) continuatio.” Seneca, Na- tur. Quaest. lib. xi. J “ The great advantage of this idea of a whole is, that a greater quantity of truth may be said to be such as the centrum (fig. 453.5), reminds me as strongly of its original whole quantity, viz. Jig. 453., from which it has been meta- morphosed as a dorsal spinous process (1, 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. For when, as in Jig. 455 , we equate those segments which are proportionally different, we re-establish uniform series. Prop. XXI. The knoivlcdge 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 1 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 the whole is greater than its parts, needs no comment to sustain it ; but that the part standing alone per se still refers to the whole quan- tity of which it is the part, requires to be insisted upon much oftener, for at first sight we are apt, without reflection, to regard it as it is in the light of a perfect figure. How many anatomists are there who never waken to the idea, that every lesser seg- ment of the spinal axis refers to the greater whole quantity ; and yet in this interpretation the law of formation enshrines itself. “L’ensemble de tous les ordres de perfections relatives, compose la perfec- tion absolue de ce tout.” Bonnet, Contemp. de la Nature, part i. chap. iii. 634 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 (Jig. 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 costte to the cervical vertebra, in order to equate this segment to the thoracic plus character of Jig. 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 knowing the full di- mensions of whole or uniform quantities , we 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 spinal 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 manifestly 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, &c. Uniformity must, therefore, alone charac- terise the original archetype series, not only of all spinal segments such as they appear in the one spinal axis (fig. 455.), but the Ike original archetypal uniformity must be that whole quantity from which all segments of all spinal axes have been degraded. And diver- sity or specific difference will at the same time get its proper interpretation; for if a mammal cervical vertebra be diverse to a costo-vertebral thoracic archetype by reason of being proportionally different, and rendered so by the simple subtraction of its sternal piece and ribs, then, as the like difference or |j variety characterises all cervical or lumbar segments of animal skeletons of the classes mammals, birds, reptiles, &c. from all thoracic costo-vertebral archetypes of the same ani- !j mals, it will hence appear that such diversity or specific variety has originated by the law of proportioning from whole archetype quantities. 1 draw the conclusion, therefore, that as an archetype series of sternal costo-vertebral segments, ranging from 1 to 24 of fig. 455., is the original of the mammal spinal axis, so may it be inferred that such an archetype series is the original of all spinal axes, what- ever be their existing variety ; and the law by which such variety occurs is the simple pro- cess of degradation or subtraction from the |j archetype series of sterno-costo-vertebral seg- ments. There can, I believe, be no other true interpretation of the law of unity in variety than this. Prop. XXIII. The mammalian cervix is not limited to the fixed number of seven cervical ;j vertebra;. — A general rule may have excep- |j tions, and anatomists may still indulge the as- sertion, that “ the exception proves the rule but, as I take it, the exception only proves |j that the rule has a flaw in it, and that such ex- ception can prove nothing more than this, namely, that error rests somewhere in our in- pretations of the law of formation. When I say that there are many grave excep- tions to the general rule that the mammal cervix is developed of seven cervical vertebrae, I am but recording facts — anatomical facts — which are exceptions to the rule. And while 1 here endeavour to develop the true evi- dence of the universal law of formation, 1 do not purpose doing so irrespective of those exceptional facts, for I believe that they must be interpreted before the law can be estab- lished truly. The neck of one species of sloth (b ,fig. 450.) possesses nine cervical ver- tebras, while the neck of another species (a) SKELETON. 635 contains seven. The human cervix (b, fig. wherein the cervix counted only five or six; 457.) occasionally develops only five or six. I and I have no doubt, that if we dissected have seen some species of the monkey tribe other mammalian bodies as frequently as we Fig. 456. A, the neck of the sloth ( Bradypus didactylus), representing the costo-sternal quantities lost to the seven cervical vertebrae ; b, the neck of another species of sloth (A. tridactylus ), exhibiting the loss of costo-sternal quantity, from nine cervical vertebrae. In both figures it is shown how the numerical difference of vertebrae of the cervix depends upon the number of metamorphosed archetypes. do the human subject, we should find also in them many exceptions to the rule which we now call general. But these exceptions will be called “ ano- malies ’’ by the special anatomist. To this I answer, that if we understood fairly the true interpretation of the universal law, we should forthwith blot out the word anomaly from anatomical nomenclature ; for there can be no anomalies any more than there can be exceptions to the universal law. Anomalies, such as they appear upon the bodies of one species, as, for instance, the cervical ribs (a, b ) ol the cervical vertebrae (6, 7 of b, fig. 457.), are, in reality, not more remarkable to the normal condition of that species than the figure and proportions of one species {a, fig. 456.) are to those of another and different species (b ,fig. 456.). The same law presides over aii conditions of formation. * Prop. XXIV. The number of cervical vertebra in the mammal cervix depends upon the number of archetypal costo-vertebral figures which have suffered metamorphosis. — Even if it were true that the mammal cervix invariably contains the fixed number of seven vertebrae, still there would appear no reason why we should not interpret the fact in the following mode, namely, that the seven cervical vertebrae of fig. 455. are those pro- portional osseous quantities left standing after the metamorphosis of the ribs (1, 2, 3, 4, 5, 6, 7) of seven costo-vertebral archetypes. For it is evident that cervical vertebrae do, * “ Tout phenomdne dans la nature est lid a l’en- semble ; et, quoique nos observations nous semblent Isoldes, quoique les expdriences ne soient pour nous ! fiue des faits individuels, il n’en resulte pas qu’elles le soient rdellement ; il s’agit seulement de savoir comment nous trouverons le lien qui unit ces faits ou ces e'venements entre eux.” Goethe, CEuv. d’Hist. Nat, Introd. p. xi. traduits par Martins. like the thoracic figures, contain costal ap- pendages, although in rudimental propor- tions. In the cervical vertebrae the costal pieces are liable to a plus condition (a b, of b, fig. 457.). In the thoracic vertebrae the costae are fully produced. Fig. 457. a, the human cervix, numbering only five cervical vertebra of normal quantity, owing to the pre- sence of a, b, the cervical ribs persistent on the 6th and 7th vertebra ; b, the cervix of the sloth (2?. tridactylus), which numbers as many as nine cervical vertebra, in consequence of the metamor- phosis of nine costo-sternal quantities. If it were possible to raise a rational objec- tion to the above mentioned interpretation of the cervical spinal region, I would then re- mark that “cervical ribs” do still further prove the truth of what I advance concerning this region of the spinal axis. For is it not true that when the sixth or seventh cervical 636 SKELETON. vertebrae of B,fig. 457., produce the costae a b of greater dimensions than ordinary, these segments of the spinal axis are but resembling somewhat more completely the thoracic costo- vertebral archetypes (such as 8, c, cl, of b, fig- 457.) ? Whenever, therefore, the sixth or seventh cervical vertebra produces the cervical ribs, I may interpret the occurrence of this “ ano- malous” fact in this way, viz. that a greatei proportional of the archetype costo-vertebral quantity (such as 8, c, cl, of b, Jig. 457 .) re- mains to the sixth and seventh spinal segment than is generally the rule. Cervical vertebrae, therefore, whether with or without the plus cervical ribs, are still the proportionals of full thoracic costo-vertebral forms ; and the number of cervical vertebrae simply depends upon the number and degree of metamor- phosis to which thoracic costo-vertebral forms have been subjected. When the cervix de- velops seven vertebrae of those proportions, such as we ordinarily find in the mammal body (a, fig. 456.), all we can say of it is, that seven thoracic archetypes have suffered metamorphosis of the ribs to the cervical degree ; and when the mammal cervix ex- hibits only five or six vertebrae of cervical degree (is, fig. 457.), this occurs by reason of the fact that the seventh vertebra of b is not metamorphosed to cervical degree, but still retains a large proportional of the rib (b). When the mammal cervix (tc,fig. 457., or b, fig. 456.) produces nine cervical vertebras, then the simple interpretation is, that nine quantities, equal to those of the thorax, and which I have represented in dotted outline, have had the original plus costo-sternal quan- tity subtracted from them. Prop. XXV. The presence of cervical ribs subtracts from the number of cervical vertebra, ancl adds to the number of thoracic archetypes. —Whenever cervical ribs (a, b of a, fig. 457. and 458.) are produced upon the sixth and seventh cervical vertebrae, the numerical length of the cervical region of the mammal spine is diminished to the serial line of five cervical segments, which we call cervical ver- tebrae ; and there and then by the occurrence of this fact, which subtracts from the cervical vertebral numbers, the thoracic costo-ver- tebral spinal region is added to and becomes numerically greater than we ordinarily find it. By as much as the ordinary cervical re- gion is lessened, owing to the presence ol cervical ribs, by so much is the thoracic region increased owing to the same cause, viz. the presence of cervical ribs. The con- verse of this condition would happen if ribs were subtracted from the thoracic spinal re- gion ; and we would then find that by as much as the thoracic region was lessened by so much would the cervical region be in- creased. What other rational interpretation can be given of this condition of balancing between the cervical and the thoracic spinal regions except this, namely, that the nu- merical difference of both regions occurs by the presence or absence of full costal forms ; and that the condition of either region of the spinal axis is influenced by the simple law of subtracting the ribs from whole thoracic costo-vertebral quantities.* Prop. XXVI. The length of the thorax depends upon the number of persistent costo- vertebral archetypes. — When I say that the numerical length of the cervix depends upon the number of costo-vertebral archetypes which have undergone a metamorphosis of osseous quantity down to cervical degree, it will fol- I low that the numerical length of the thoracic region must depend upon the number of those original archetype costo-vertebral figures left J standing in spinal series. That same law of formation which influences the numerical length of one spinal region must also influence the numerical length of the adjacent spinal regions, and so we invariably find this to be the case. When the cervix of fig. 458. pro- duces cervical ribs a on the vertebr 6, nil Fig. 458. the next succeeding, the thorax is increased. When the loins produce lumbar ribs, suc- ceeding the vertebra 19 b, the thorax is still increased. When the thorax is numerically lessened, by subtracting the ribs a b from the vertebrae 6 19, the cervical or lumbar spinal regions are numerically increased. Now all this variation in the spinal regions no doubt depends upon the number of per- sistent ribs, whether normal or abnormal. The degradation of the costo-vertebral ar- chetype whole quantities, is the law which produces all minus or special variety, and * As it seems that the presence or absence of the costal pieces varies the quantitative character of the j vertebrae, making them thoracic by their plus pre- sence, and cervical by their almost total obliteration, so the reader will, from this expression of the fact, j readily gather the tendency of my remarks, which is this, namely, that the archetypal quantities of the cervical spinal region are equal to those which are still persisting for the thorax in full sterno-costo- vertebral proportions. This, be it right or wrong, is SKELETON. 637 yields the mammal spine as it is, normally or abnormally. Prop. XXVII. The numerical length of the lumbar spinal region depends upon the num- ber of archetypes subjected to metamorphosis. — The first lumbar vertebra, that which succeeds 19, b, fig. 458., counts twentieth from the occiput, and thirteenth after the last cervical vertebra, when this latter counts seventh from the occiput ; and it is ac- cording to the character of the costal ap- pendages of this first lumbar segment of the spinal series, that we are inclined to regard it as belonging to the category of thoracic or of lumbar spinal segments. When it produces articular costae, it stands in true thoracic character, and adds to the number of thoracic segments, at the same time that it subtracts from the number of lumbar vertebrae. In this respect, namely, that of influencing the numerical series of the spinal regions ac- cording as the ribs are standing plus upon it or otherwise, this first lumbar vertebra is similar to the seventh cervical vertebra. As the numerical length of the cervix depends upon the presence or absence of cervical ribs, produced from the seventh cervical vertebra, and as this very condition influences also the length of the thoracic series, so does the numerical length of the lumbar region de- pend upon the presence of lumbar ribs pro- duced in plus or minus dimensions from the first lumbar vertebra ; and this is the very fact which also influences the length of the thoracic series. The inference to be drawn from these facts is obvious enough. The abnormal as well as the normal conditions of the lumbar spine, in regard to the ribs, prove that lumbar vertebras, as well as cervical ver- tebra, are proportional figures degraded from the costo-vertebral thoracic archetype quan- tities such as I have drawn them in fig. 455., from 1 to 24. Prop. XXVIII. The numerical length of the sacral and coccygeal series is not fixed, and this is owing to the same fact of archetypes im- dergoing metamorphosis. — Though the human anatomist speaks of a spinal figure under the name of first sacral and first coccygeal vertebra, it is not hence to be inferred that this form pre- sents, in all human spinal axes of a fixed and invariable character, either as to osseous quan- tity or numerical position. In order to prove that such is the changeable character of the form named sacral and coccygeal vertebras, we have only to fix attention upon its nume- rical situation in several spinal axes of even human species ; and w'e shall find that the first sacral vertebra of one spine is the last lumbar vertebra of another spine. In like manner we shall see that the first coccygeal the idea I wish to create as contradistinguished from the ideas promulgated in “ The Homologies of the Vertebrated Skeleton,” where I find that the author, in his figures of the archetype of mammalian, avian, and reptilian forms, leaves their cervical regions standing in their class proportions, as though these were “ archetypal,” “ the general,” “ the fundamental type.” vertebra of one spine is the fifth sacral of another spine. In the “ normal ” condition of the human spine, the first sacral vertebra (fig. 4 55./) counts as the twenty-fifth reckon- ing from the occiput ; but if we will compare and examine a large number of human ske- letal axes, we shall see that the twenty-fifth spinal segment or vertebra is not always standing in sacral condition. I have found that this twenty-fifth spinal vertebra is some- times in lumbar and sometimes in sacral form, a circumstance which proves that sacral character is mainly owing to the juxta- position of the iliac bones. Upon which- ever vertebra of the lumbar spine, whether it be f or the one before or behind f fig. 455., the iliac bones abut, this determines its sacral character. This sacro-iiiac junction does not always occur between the twenty- fifth vertebra of the human spinal series and the iliac bone. I have occasionally seen it at the twenty-fourth and at the twenty-sixth numerical vertebra of spinal series. When the sacro-iiiac junction happens between the twenty-fourth vertebra and the iliac bone, the human lumbar spine reckons only four ver- tebrae, provided the last thoracic be the nineteenth. When, again, this junction takes place between the twenty-sixth vertebra and the iliac bone, then the lumbar spine reckons six vertebra provided always the last thoracic costo-vertebral segment be the nineteenth. These variations in the numerical length of the lumbar spine, occur according to the spinal position of the iliac spinal junction ; and it will hence appear that the sacro-coccy- geal series of spinal forms must also be in- fluenced by the same facts. Prop. XXIX. A comparison of the same numerical vertebra in all human spinal axes will prove the truth of the present interpre- tation of the law which governs the develop- ment of all vertebral forms , not only in the same spine, but all other spines. — When I say that the seventh cervical vertebra of fig Abb. is a proportional metamorphosed from its own costo-vertebral archetype or whole quantity, and which archetype is the equal of that which stands as the first thoracic costo-vertebral form, viz. that marked 8 in fig Abb., have I not a certain proof of the truth of this interpretation, when upon comparing this seventh cervical vertebra of fig. 455. with the seventh cervical vertebra of a, fig. 457., or that of fig. 458., I find that the very same numerical seventh cervical vertebra is, in the one skeleton (fig. 455.), of cervical, and in the other skeleton (fig. 458.), of thoracic cha- racter. For it is the presence or persist- ence of the cervical ribs which determines its character in this case as thoracic, and it is the absence or rudimentary condition of the ribs which in the other case stamps it as cer- vical. Again, when I say that the twentieth spinal vertebra of fig Abb., reckoning after the occiput, and which twentieth vertebra is the first lumbar vertebra, must be considered as a proportional or lesser form metamorphosed from such another whole archetype as the 638 SKELETON. thoracic costo-vertebral figure, have I not a proof of the truth of this reading in the fact, that this twentieth spinal vertebra in one spine presents in lumbar form, and in another spine in thoracic costo-vertebral form. How much closer can we urge the science of com- parison to yield to us the secret of nature’s law of formation than by comparing the same numerical vertebra with itself, and discovering that it is proportionally diverse in several individuals of one and the same species ? If, therefore, the same vertebra be in many indi- viduals in all those same conditions of pro- portional variety in which we find all vertebrae throughout the serial order of the one spinal axis from atlas to the last coccygeal no- dule,— if this same vertebra (seventh) shall prove, upon a comparison of it in many ani- mal skeletons, of the same variable propor- tions as we find to exist between a cervical, a thoracic, a lumbar, a sacral, and a coccy- geal vertebra in the same spine, it must be evident that the law which governs the pro- portional variety of the same vertebra in many animals is the same as the law which governs the proportional variety of all ver- tebrae in the one animal. So true is this that I hold it to be possible to take the same spinal vertebrae of normal and abnormal con- dition from a plurality of skeletons, and construct with them a spine of the same quantitative variety as it exhibits in the serial line of cervical, thoracic, lumbar, sacral, and caudal vertebral regions. Prop. XXX. The anomaly is a link in the chain of form. — False interpretation of the law of form is the source of all those conditions which are spoken of as being anomalous to the law. When anatomists name cervical or lumbar ribs as being anomalous to the human neck or loins, it is a proof that they do not under- stand the law of development which governs the human and all the general connected chain of special variety. The anomaly (6 a of fig. 458.) is to the normal form of the same cervical vertebra of fig. 455. just what one normal form (19 b/fig. 458.) is to the other before or behind it in series. The cervical and lumbar ribs are to the cervical and lum- bar vertebrae just what the thoracic ribs are to the thoracic vertebrae. And the seventh cer- vical and first lumbar vertebrae, whether these produce the rib in plus or in rudimental form, are to each other just what ordinary cervical and lumbar vertebrae are to thoracic costo- vertebral archetypes, namely lesser quantities metamorphosed from greater quantities. Hence does it plainly appear that normal as well as abnormal cervical and lumbar vertebrae are alike only proportionally various to tho- racic costo-vertebral archetypes, and hence may it be understood that all variety, whether normal or abnormal, springs by the simple metamorphosis of the archetypes, indicated in dotted lines at the neck and loins of fig. 455. While human anatomists falsely interpret the ordinary cervical and lumbar vertebra as being whole quantities, then every elemental structure which occurs plus upon a cervical or lumbar vertebra, will by them be named “ anomalous.”* Cervical and lumbar ribs are thus accounted anomalies. But when we shall regard cervical and lumbar vertebra through the medium of the idea here enter- tained of them, viz. that they are lesser things degraded, proportioned, or metamorphosed from greater whole quantities, such as costo- vertebral archetypes, then may we reasonably know the origin of cervical and lumbar ribs, and interpret these as being larger propor- tionals of the costo-vertebral archetypes than what we ordinarily find in cervical or lumbar regions. f Prop. XXXI. All the spinal segments of all classes and species of vertebrated animals ars only as the vaiiable proportionals of sternu- costo-vertebral archetypes. — A comparison of those several regions of the spinal axes re- presented in fig. 459. will prove the truth of the assertion, that the law of formation by which all skeletal species are produced, and the law which produces the regional variety of cervical, thoracic, lumbar, sacral, and caudal in the one skeletal axis, are one and the same in operation. When I take the cervical spine of a bird (a b) (the ostrich), and com- pare it with the lumbar spine (c d) of the same animal, I find that both regions of tile same spine present the like proportional cha- racter. The segment (b, a,,b,c, d ), which is the thoracic sterno-costo-vertebral archetype or whole quantity, is preceded by a series of pro- portional quantities gently graduated and de- clining into the cervical minus figure marked a, a. In like manner (c, a, b, c) the arche- typal sterno-costo vertebral quantity, the last of the thoracic region, is succeeded by a series j1 of proportional quantities, graduated in the same way, and declining into the lumbar minus figure marked d, a. Again, when I compare the human cervical spinal region (e f) which “ anomalously ” produces cervical ribs, with A b of the bird’s cervix, which normally de- : velopes the cervical ribs, I only find a mani- festation of the same law. And the bird’s lum- bar spine (g ii) is only in the same way pro- portionally characterised as the bird’s neck (a b), or the mammal neck (ef), or the ! * “ La loi de la continuite porte que la nature ne laisse point de vide (anomalie) dans l’ordre qu’elle suite.” Leibnitz, CEuv. Philos. Nouv. Essais, liv. iii. p. 267. t The continuity of the chain, not only of an animal kingdom, but even of the serial spinal axis, j is so evident a truth, and so sound a generalisation, that when any form shall appear abruptly inter- rupting this continuity, and, as it were separating members of the chain apart and isolated fi'om each other, it may be taken for granted that we are ignorant of its true nature, and its general and special relations to all other units of the series. 1 The true object of science is the discovery of sack jj points of analogy as will relate the anomalous form to the general chain of which it is a unit.. The jj differential character of the thing or things is that which strikes the uninitiated at first sight always. “ Itaque convertenda plane est opera ad inquirendas et notandas rerum similitudines et analoga, tam in- tegralibus quam partibus : illse enim sunt, quie naturam uniunt, et constituere scientias incipiunt.” — Bacon, Novum Organum, aph. xxvi. SKELETON. 639 lizard’s neck (i k), or the lizard’s loins (l si). Now as all the units of these several regions Fig. 459. A b, c D, tlie neck and loins of the ostrich ; E F, the human cervix, with cervical ribs ; g h, the loins of a mammal ; i K, the neck of a lizard ; l M, the loins of a saurian (crocodile) ; N o, a part of the ophidian thoracic skeleton. of the same and of different species, evidently illustrate the simple law of the archetypal plus ens of the thoracic sterno-costo-vertebral quantity, undergoing a graduated metamor- phosis into less quantities of a neck or loins, so I have equated in dotted outline, all those parts which the minus quantities have ac- tually lost ; and thus 1 have in idea given creation to their whole or plus originals ; and the reader will observe that by this very mode of equation between the plus and minus seg- ments of A B, C D, E F, G II, I Ii, L Jl, I have equated them likewise with the plus series N o, which represents part of the ophidian thoracic skeletal axis. The fact likewise may be noticed in this place, which will be more fully considered hereafter, that in Jig. g ii the parts b, c, d, which are represented in dotted outline as the quantity lost to the shortened ribs a, a, are those very structures which in the saurian venter opposite its lumbar spine l m, appear as the ventral ribs ( c , c), joining a ventral sternum (d, d ) ; and there appears ventrad of the saurian cervix (i k) that series of osseous pieces marked c, d, amongst which I find the bones known as clavicles and coracoids. Are these clavicles and cora- coid bones which appear ventrad of the cer- vical spine, in reality only as persistent parts of the whole sterno-costo-vertebral arche- types ? Fig. 460. a, the seventh cervical vertebra of the human neck ; b, the seventh of a bird's neck ; c, the seventh of a serpent’s spinal axis; D, the seventh cervical vertebra of the human neck, producing a, b, the cervical ribs ; e f, g h, vertebral segments of the ostrich, taken from the caudex E, neck f, loins G, and thorax h. When I compare all those spinal regions of several species of animals represented in 640 SKELETON. fig. 459., I find that the difference between them is resulting by a subtraction of different parts from each. But when guided by the light of comparison, I supply to each those parts which it has lost, then I render them all equal as whole quantities. Now, if the ques- tion be here asked upon what authority I act in thus equating the minus ens with the plus, by adding to the former that quantity by which it is less than the latter ? I may answer that nature herself teaches me the rule in offering to my consideration the following facts: — In fig. 459. abcd represents the same numerical spinal segment of different animals, and it manifests only a proportional variety. Again, I find that, numerically dif- ferent vertebrae of the same spine e f g h, exhibit the same proportional variety. Again, I choose numerically different vertebrae from the spinal axes of different classes of animals (a b c,J%.461.), and they present in the same Fig. 461. abc, vertebrae taken from, the human neck (a), the bird’s thorax (b), and the crocodile’s loins (e) ; n e f, vertebra: from any region of the ophidian spinal axis. proportional variety ; and, lastly, I take dsf numerically different vertebrae from the same spine, and they represent uniformity amongst themselves ; but this uniformity is occurring only by reason of the fact that these units are of equal quantity. Now, upon comparing all those spinal segments ol figs. 460. and 461., it becomes manifest that the thoracic or ventral circle a, b, c, which I have supplied in dotted outline for some, indicating the quantity lost or substracted, is actually created for others ; and hence it appears that the only difference between them, one and all, is in that degree in which the rib ( a b) falls short of the sternal median line c. The law of species therefore appears to be the law of proportioning lesser quantiti.s from whole and complete quan- tities. It is the metamorphosis of ribs at the neck, loins, sacrum, and caudex, which renders these regions different to the thorax. Be- tween those spinal segments to which the plus ribs are present in one animal (b, /?g.46I.), and those spinal segments from which the ribs are metamorphosed in another animal (a, fig. 461.), I hold comparison, and I find the ra- tional conclusion, that the parts or ribs (a,b of a) which are absent from one class of ver- tebrae are identical with the parts or ribs (a, b of b) which are present to another class of vertebrae. And that specific difference, as it exists between two or more animals, is ac- cruing by the loss of known parts, viz. ribs. For which reason I am led to name that skeletal form (n o ,fig. 459.) which holds all its ribs (a, b, c,) to be archetype of all other skeletal bodies of the four classes from each of which variable numbers of original ribs are subtracted. And for the like reason, I sav, that the thoracic region of the one skeletal axis which holds its ribs is archetype ef all other regions of the same spinal axis from which the ribs have been metamorphosed. The law of formation therefore is the meta- morphosis of ribs. The original or archetype skeletal axis is therefore one of costo-ver- tebral character from occiput to the extreme caudal tip. The metamorphosis of the ribs of this original, or archetype, or continuous 1 series of costo-vertebral quantities, yields all species of skeletal axes. If all skeletal axes were similar in osseous quantity to the thoracic ophidian (n o ,fig. 459.), there would be no specific variety, for all skeletal axes would then be similar to one another. But they are not all quantitatively similar, and this is the reason that they are specifically various, having severally lost various parts, which parts are to be read in the original, the uniformity, the archetype, the uninter- rupted serial line of costo-vertebral spinal segments. Prop. XXXII. The Hyoid Apparatus occurs, opposite to the cervical spinal region, where we j know costal quantity to be lost. The hyoid ap- paratus refers to the cervical vertebra;, and con- sists of their ribs metamorphosed. — W herever plus or archetypal or thoracic osseous quan- tity persists complete in all its parts, there, in that place, we never find a new apparatus } posited. It is as impossible for a new or specifically various apparatus to appear where archetypal osseous quantity exists, either among the four classes of skeletal forms, or the four spinal regions of the one skeletal figure, as it is for two things to occupy one and the same place. I call the thoracic sterno costo-vertebral apparatus the archetypal or plus quantity of the spinal axis, and I find SKELETON. 041 that, because it is plus quantity, no new appa- ratus ever appears, or can appear, at that locality which it occupies. Anatomical re- search has never yet discovered, and never can at any future time discover, a new and hitherto unknown osseous piece of any form or cast whatsoever at that spinal region where the thoracic apparatus stands fully created from the sternum in front to the spinal bone behind. Anatomical science may safely ven- ture to predict that the searcher after variety and specific differences will never find in any skeletal form, whether of extinct species, of existing species, or as yet uncreated species, a new. osseous apparatus happening where the complete thoracic apparatus occurs. It can- not occur at this locality, because the full archetypal osseous quantity is already existing in thoracic structure. There is no regional spinal variety, and no new or special apparatus, in the thoracic ophidian skeletal axis, be- cause the full or archetypal osseous quantity already exists in the thoracic form. The ophidian skeleton has neither cervix, loins, sacrum, clavicles, coracoid bones, ventral ap- paratus, pubic bones, or marsupial bones, be- cause the whole length of its spinal axis is already persistent in costo-vertebral thoracic character. If it be said that these various apparatus are not created for the ophidian skeleton, because they would not suit this particular cast of form, and that the “ nihil supervacaneum ,” is a rule with nature in the construction of animal beings, I grant the truth of this most freely ; but still I will main- tain that this has no power to invalidate my present argument, which is conducted not to disprove design, but to demonstrate that all design occurs by the omission of elemental structure proper to plus archetypal structure. I grant that the ophidian thoracic skeleton, though deprived of all the above-named special apparatus, is as perfect in its own design as the “ paragon of animals” himself is, or as any other cast of skeletal form furnished with those same apparatus ; but yet I say that it is as impossible, as it would be unfitting, for creative force to give birth to such a form as the thoracic ophidian, and furnish it at the same time with clavicles, coracoid bones, ven- tral apparatus, marsupial bones, cervical, lum- bar, and sacral vertebrae. Moreover, I assert it to be likewise impossible for creative force to produce any of those apparatus, or all of them, for a skeletal figure, if such figure were not at the same time to manifest a cervical, a lumbar, or a sacro-caudal spinal region. In whatever skeletal form the cervix or loins or sacro-caudal spinal region is developed, in this same form alone can we find the hyoid and ventral apparatus. It is quite true that a skeleton may be found characterised with the cervical and lumbar, &c. vertebras, and yet not characterised with clavicles, coracoid bones, ventral ribs, or marsupial bones ; but where these do exist, then such a spinal axis as that of the ophidian, consisting of costo-vertebral archetypes, cannot at the same time exist. The continuity of such a thoracic spinal axis must be broken directly any special apparatus, suchasl,2of Jig. 462., or 1,2,3, 4 of, j%.463., appears upon it. A thoracic skeletal axis, irj Fig. 4G2. Showing that the hyoid circles 1, 2 appear as the ribs of cervical vertebra;, and hold serially related to those ribs 3, 4, 5, 6, 7, which, having been subtracted from the thorax, give to this latter its particular form. order to be of what I call full plus archetypal dimensions, should present its spinal segments, one and all, from the skull to the other.ex- .reme, in sterno-costo-vertebral quantities, such as the thoracic spinal segments of the human skeletal axis. Upon such a skeletal axis there could not appear such an apparatus as the hyoid structure (1,2 of Jig. 462. or 1, 2, 3, 4 >f/?g. 463.), or the clavicles, the coracoid bones, marsupial bones, pubic bones, or ventral appa- ratus, and for this reason, namely, that all the isseous quantity which goes to construct these, vhen fitness and special design demand their presence in the skeleton, must be drawn from he costal and sternal quantity of the continu- ous series of archetypes, and in such case the resence or creation of the hyoid species of VOL. IV. apparatus must imply the metamorphosis of the other costo-sternal species of form. Now, the ophidian skeleton itself proves to be im- perfect when compared to this standard ske- letal figure, consisting of sterno-costo-verte- brai archetypes ; for the sternal median structure is lost to the ophidian throughout its entire length. In the ophidian skeletal axis, 1 find the cervical region, or that division of the spinal segments which immediately succeeds the occiput, having the costte or ribs persisting ; but those ribs are free, that is to say, they do not meet the sternal line in front. The sternal pieces and the sternal ends of the ribs are wanting ; but in that very locality where these should appear, if the archetypal sterno-costo-vertebral segments were perfect 6+2 SKELETON. and enclosing thoracic space completely, ap- special design of an ophidian hyoid apparatus, pears the new apparatus named hyoid. The By an actual necessity, therefore, and in the absence of the sternum and sternal ends of relationship of cause and effect, it appears the ribs becomes the presence of the simple that the presence of a hyoid apparatus (1,2 Fig. 463. The cervical spine of the osseous Fish, Exhibiting the hyoid apparatus 1, 2, 3, 4, as being the original costo-stemal quantity proper to those vertebras which immediately succeed the occiput. In both figs. 462. and 463. the parts indicated in dotted outline are those quantities of the archetypal series of sterno-costo- vertebral circles which, being subtracted, give to both forms their class characters. If such parts still existed for both forms, these would approach the original character of plus uniformity, and thereby would leave no distinction between the hyoid apparatus, 1, 2, 3, 4, and the thoracic apparatus, 5, 6, 7. In both figures it will be marked that the variable number of hyoid circles depends upon the variable number of those costse which have suffered metamorphosis. of fig. 462.) must be the metamorphosis of a costal apparatus at those spinal segments which immediately succeed the occiput, and the same appears true of every other special apparatus produced upon the skeleton form. The appearance of any or all kinds of special apparatus implies the metamorphosis of all or some of the costal and sternal quantities. Consequently, therefore, it must follow that as the original costo-sternal apparatus of the cervical spinal segments may he regarded as homologous with the thoracic costo-sternal apparatus, so will the hyoid apparatus (1, 2, 3, 4, fig. 463.), which is constructed of the cervical costo-sternal quantity, bear some analogy, more or less, to the thoracic appa- ratus (5, 6, 7, 8, 9, \0,Jig. 463.). In all ske- letons I see an analogy, more or less strongly marked, between not only all hyoid apparatus as special designs {Jig. 462, 463.), but between these and the thoracic apparatus. The source of this structural analogy, no doubt, is, that the hyoid apparatus (1, 2 of Jig. 462., and 1, 2, 3, 4 of Jig. 463.) is specially modified from the original structure at the cervix, which structure is costo-sternal proper to the cervical spinal region, and, as such, is the true structural homologue of that apparatus which elsewhere constitutes the thorax. The hyoid apparatus, at one spinal region, is not the thoracic appa- ratus at another spinal region ; for to assert this would be as absurd as to say that the thorax of one skeleton was the thorax of another ; in other words, as to assert that duality was unity. How can the hyoid appa- ratus (1,2, 3, 4 of Jig. 463.) be rationally named the thoracic apparatus, when both ap- paratus may exist at the same time in the same skeleton ? When I see the hyoid apparatus (1, 2, 3, 4) of a fish {Jig. 463.) existing with the thoracic apparatus {5—10, Jig. 463.), and both the same apparatus existing in a mammal skeleton {a, b, 8 — 19, Jig. 455.), why should I therefore say that the hyoid apparatus of the fish was the thoracic apparatus of the mammal pushed upwards into the fish’s throat? If the i hyoid apparatus of the fish were the thoracic apparatus of the mammal, then, strictly speak- ing, the fish could have no hyoid apparatus at all, and wherefore should we still continue top call that hyoid which in reality was thoracic r Evidently anatomists are only disputing about the shadow of nomenclature in their ignorance of the real entity of form, and the law which modifies to infinite variety. Evidently, while they record how unity or uniformity is varied they cannot describe or figure the charactei of unity, and they never will, so long as the' dispute about variety without first ascertain1 ing the source of this variety. What is tin truth concerning the source of this remarkably analogy between all hyoid apparatus as such (i! Jigs. 462, 463.), and all thoracic apparatus a such ? 1 believe the source of the analogy t be this, namely, that the thoracic apparatu happens at variable localities of the spin :) axi| according to the position whereat sternc costo-vertebral archetypal structure persists, a, from 8 to 19 of Jig. 455., and 5 to 10 oiJigAb\ This thoracic apparatus may, according to nt cessity, persist at any region of the spin; length, or at all regions, because the origin' archetypal skeletal axis is one of a contimioij series of thoracic segments. Where it dot persist, as in Jig. 463. from 5 to 10., there i new apparatus can recur ; but where the thy racic apparatus has undergone metamorphosi as at cervix 1 to 7 of Jig. 455., and 1 to 4ofy/ 462. or 463., there and there only a new speci apparatus, such as the hyoid, can happe SKELETON. 643 Where this original or archetypal thoracic structure suffers metamorphosis, as at the neck, there the hyoid apparatus appears as part of the original thoracic quantity, and hence it is that the hyoid apparatus, as such, bears an analogy with the thoracic apparatus as such, because the original of the former is thoracic quantity. When this original thora- cic quantity undergoes metamorphosis imme- diately alter the occiput, then the vertebral cervix is formed, and also the hyoid apparatus below it. As both these have come by the metamorphosis of costo -vertebral quantity, so do we find them bearing analogy to those seg- ments, next succeeding them in spinal series, — those segments, namely, which persist as whole archetypes, and constitute the thorax.* Prop. XXXIII. The Ventral Apparatus oc- curs opposite to the lumbar spinal region, where we understand that costal quantity is lost . The ventral apparatus refers to the lumbar vertebra and consists of tlieir ribs metamorphosed. — With the mere change of name from hj-oid to ven- tral apparatus, I may apply the foregoing remarks, which prove that the hyoid appa- ratus has come of the metamorphosis of the ribs of cervical vertebrae, to demonstrate, also, that the ventral apparatus ( 1, 2, 3, 4, 5, 6, 7, Jig. 464.) has come of the metamorphosis of ribs proper to the lumbar vertebrae. As the origi- nal or whole archetypal quantities from which the hyoid apparatus and the cervical vertebrae have been metamorphosed are of thoracic or costo-vertebral proportions, so, in like manner. Fig. 464. The lumbar spine and ventral apparatus of the Crocodile, Showing that the ventral ribs (1 to 7) are the proper continuations of the lumbar costal pieces, b, c, d, e, f g, h, with which they correspond numerically. I believe that the original or whole archetypal quantities, from which the ventral apparatus ( I to 8, fig. 464.) and lumbar vertebrae (b to h , y?c.464.) have been metamorphosed, are also of thoracic costo-vertebral proportions. In the ophidian thoracic skeleton, I find that that region of the spinal axis which corresponds numerically to the cervical region of the mam- mal spinal axis presents in thoracic costo- vertebral proportions ; and therefore I say, that the true interpretation of the law of for- mation, which strikes the skeletal neck of the mammal specifically different to the skeletal neck of the ophidian, must he this, viz , that the costo-vertebral original of the mammal neck is equal and homologous to the persisting figure of the ophidian neck ; but that meta- morphosis has modified the original quantity of the mammal neck (figA55.) to its existing appa- ratus of hyoid arcs a b and cervical vertebrae, whereas the original quantity of the ophidian neck still persists. In the latter we therefore find the cervix in thoracic costo-vertebral quantity, having appended to it, in front, the * Professor Owen considers the first circle of the fishes’ throat apparatus as the only part of it which is homologous to that of other animals, and ac- ■ counts all the succeeding arches (three or more in number, and all similar to the first, however,) as , “ appertaining to the system of the splanchno- j skeleton, or to that category of bones to which the heart-bone of the ruminants, and the hard jaw-like pieces supporting the teeth of the stomach of the lobster, belong.” See Homologies, &c. simple hyoid apparatus metamorphosed of the sternal elements. In the former we find the cervix consisting of vertebrae with stunted ribs, which are occasionally produced to more imposing proportions, being then called “cer- vical ribs” and still having appended to them, in front, the hyoid apparatus. The same in- terpretation will apply, also, to the mammal lumbar spine {fig. 455.), viewed in connec- tion with the fibrous bands named “ lines transversce ” (20 to 24) and “linea alba'” ( d to e). And still more evidently will the same interpretation apply to the saurian lumbar region (b to h, fig. 464.), and the ventral appa- ratus (1 to 7); for this latter structure is evidently composed of sternal and costal ele- ments. What the hyoid apparatus is to the cervical vertebrae, namely parts of the thoracic original whole quantities, just in the same re- lation stands the ventral apparatus of fig. 464. to the lumbar vertebrae ; for I regard both these latter structures to be parts, likewise, of the thoracic whole quantities. The hyoid ap- paratus refers to the cervical vertebrae, there- fore, just as the costo-sternal structures of the thorax refer to the dorsal vertebra ; and in the same relation does the ventral apparatus of fig. 464. refer to the lumbar vertebra. If we seek a proof still further that the original quantities of the cervical and lumbar regions of the spinal axis of any animal are thoracic costo-vertebral quantities, equal to those of the thoracic region of the same animal, we have this proof in the fact, that all the spiral t t 2 SKELETON. 6 it regions of the ophidian are thoracic, and there- fore in this skeleton there does not appear a cervical spine, or a lumbar spine, properly so called. If the above observations, respecting the several spinal regions, and the several appa- ratus thereunto appended, be true, then, how- ever harshly it may seem to jar against reason, in asserting that there must exist the same analogy between a hyoid, a thoracic, and a ventral apparatus, as between the cervical, the dorsal, and the lumbar vertebrae, still I do not hesitate to make that assertion, under the knowledge that the original whole quantities of each region are of thoracic costo-vertebral proportions. I do not mean to say that the apparatus of the vocal throat ( a b o'i fig. 455.), or the respiratory thorax (8 to 19 of fig. 455.), and the digestive venter (1 to 8 of y?y.464.), are identical as osseous quantities, having the same number of elemental pieces in each which we find in one, but what I distinctly repeat is this, namely, that, however broad may be the specific distinctions between the presential characters of a hyoid, a thoracic, and a ventral apparatus, when compared and contrasted with each other, still the law of serial arrangement will, if followed in the one skeletal form, and throughout the whole ani- mal kingdom, prove that they are variable proportional osseous quantities of the same original, viz., the thoracic costo-vertebral con- tinuous series of archetypes : and, therefore, I have united with dotted lines the hyoid apparatus to the cervical vertebrae, and the ventral apparatus to the lumbar vertebrae. Prop. XXXIV. Clavicles, coracoid bones, and ribs are identical parts of the costo-vertebral whole quantities or archetypes. — It is impossible to tell which of the two bones named clavicle and coracoid, in a bird, is the counterpart or homologue of the bone named clavicle in man. Anatomists are not agreed upon this point at the present time ; and, I may venture to say, they never will be, for this reason, viz., that they believe these bones to be specifically diverse bodies, and holding a permanently fixed cha- racter in all animals, when, in fact, they are identical bodies, being severally subjected to the same modification in two or more skele- tons. Whichever of these two bones (and it may be either one or the other) is made to assume the functions ami connection proper to the thing called clavicle in the human ske- leton, will be the clavicle. It is the distin- guishing mark of the human clavicle ( a b,fig. 465.), to abut by one end against the sternal piece (r), and by the other end (a) against the acromion process of the scapula ; but, strange to say, we find that both these con- nections proper to the clavicle of the mammal are divided between the two bones named clavicle and coracoid in the bird. The bone named coracoid (cl, fig. 466.) in the bird joins the sternum (/), like the bone named clavicle in the mammal ; but it is the bone named clavicle (a fig. 466.) in the bird which joins the acromion process ( b ) like the bone named clavicle in the mammal. For this reason, I say, that it is not possible to pronounce what bone in the bird is counterpart of the clavicle in the mammal, since, evidently, those very articular Fig. 465. connections which characterise the one bone, called clavicle in the mammal body, are divided Fig. 466. between two bones at the same locality in the bird. It is this circumstance which has given ! rise to so much written controversy* in the school of comparative anatomy. 1 find that the mammal clavicle (b Jig. 465.) joins the first sternal piece (e) by one end * In tlie writings of Cuvier, Geoffroy, Cams, Meckel, and others, I find the following statement respecting the identity of the. bones called clavicles and coracoids. l?y one, the furcular bone, at the root of the bird’s neck, is accounted the true ana-1; logue of the mammal clavicle. By another, this’ “ coracoid” bone, which is behind the furcular, and articulates with the sternum, is called the analogue)) of the mammal clavicle. By another, this coracoid;, bone is said to represent the coracoid process of the human scapula. By another, the two bones, furcu- lar and coracoid, are said to be clavicles proper. One states that the corresponding bone, which occurs at the root of the chelonian cervix, is a cora-) coid bone ; another avers that it is the counterpart of the clavicle ; another that it may represent either. In the tortoise, the bone is clavicle according to one; coracoid, according to another. In the casso- wary and ostrich, where one of the two bones hj rudimentary, a doubt arises as to whether this hi the coracoid or the clavicle; some prove one read- ing on the bat, some another on the monotremej some another on the lizard, others prove their owl- interpretation on the fish; and Nitsch discovers)?' a small additional rudimentary scapula in the cap; sular ligament of the shoulder of some accipitres which he says is proper to the furcular bone, am therefore the furcular bone is a clavicle. I leaWj the reader to choose his own belief out of these, if i be possible with him. SKELETON. 645 just as the first thoracic rib (7, 8, fig. 465.) itself does ; and, in this particular, the clavi- cle is like the rib. The sternal half of the cla- vicle (b fig. 465.) and the sternal half of the first rib (7, 8) are therefore as identical one with the other as the sternal halves of any other two thoracic ribs of serial order. But I see that while the ribs join the dorsal vertebrae behind, the clavicle joins the acromion pro- cess of the scapula laterally. In this latter particular the clavicle differs from the rib. Now, granting this to be a well-marked spe- cific difference between rib and clavicle, [ still maintain that there is as broad a difference ex- isting between clavicles of mammals and birds; and also between clavicles and coracoid bones. If change of place at one end from vertebra to acromion process be enough to distinguish clavicle (a, b fig. 465.) from rib (7, 8) in the mammal body, so must change of place be sufficient to characterise the bone named cla- vicle ( a fig. 466.) in the bird from the bone so named in the mammal, for the former does not join the sternum ( fifig • 466.), and the latter does abut against that bone. And true it is that the bone named coracoid ( d,fig 466.) in the bird joins the sternum (/), like a true mammal clavicle, but yet is not considered the clavicle, because its scapular end (e) joins another process than the acromion. It ap- pears, therefore, all circumstances considered, that the mammal clavicle {a, b,fig. 465.) is as homologous to the rib (7, 8) in sternal re- spect (c, d ) as it is to the bird’s so-called cla- vicle {g, fig. 466.) in scapular respect (c, b ) ; and at the same time it appears that the coracoid bone ( d,fig . 466.) of the bird is as similar to the mammal clavicle (a, b,fig. 465.), and mammal rib (7, 8) in sternal junction, as the bird’s clavicle (a, fig. 466.) is to the mam- mal clavicle (a, fig. 465.) in acromion junc- tion. What, then, is the difference between the rib, the clavicle, and coracoid bone ? It is a difference of articular connection, which all three bones appear to share in common, — a crosswise difference in articular connection, which presents us with reasons equally strong for naming either of these bones ribs, as well as clavicles or coracoids. Viewed all three as clavicles, they share the clavicular cha- racter amongst them ; for that clavicular con- nection which the one has not, the other has. Viewed as ribs, all three, they share the costal character likewise between them, and hence follows the inquiry into truth; namely, whe- ther their originals be ribs, or bodies abso- lutely distinct from ribs, passing through metamorphosis. I believe them to be ribs, or costal parts of whole costo-vertebral arche- types, and that their difference depends simply upon that act of the creative force which in the process of development bends them from the continuous line of serial costal order, and renders them cleaving articularly to various parts for the fitness of various special skeletal fabrics. The track of the law of metamorphosis which differences clavicles or coracoid bones from ribs, may be easily fol- lowed, if we will enlarge the view, through comparison, and over a sufficient number of facts. As iny?g. 467. the rib (/c) follows the rib i, 9, in serial order through the thoracic Fig. 467. The cervical spine of the Crocodile, Showing that if in idea we continue the cervical ribs, a, b, c, d, e,f g, h, i, over the cervix, in the same way as we find the thoracic ribs, k, &c., enclosing thoracic space, we then find 8, the clavicle, holding serial order with the costal continuations, 1, 2, 3, 4, 5, 6, 7, which proves the costiform character of the clavicle itself. region, so does rib i, 9, and clavicle 8, taken with the cervical rib h, succeed each other n the same serial line ; and so likewise in fig. 468, does rib e, the coracoid d, md clavicle b, succeed each other in costal irder. These bodies are similar by succes- ional position ; and the only specific aiffer- nce between them, upon which we hang the ames rib, clavicle, and coracoid bone, is this, iz., that whilst all three bodies have a ster- al articulation (c,fig. 468.), the rib (e) still olds connected with its proper vertebral iece, while the clavicle (b), and the coracoid bone (d) disconnect themselves from their vertebrae behind, and are taken up by the acromion and coracoid processes of the sca- pula.* In fig Ad'S . we find the osseous pieces marked ] , 2, 3, 4, 5, to be succeeded by the sternal rib 6, which joins the part/, and constitutes the costo-vertebral archetypal quantity of the thorax. If, therefore, the serial order of the osseous pieces a, b, c, d, e, continued into the * This fact will be more fully illustrated when 1 shall have to define the homological relations of the scapulary members. T T 3 646 SKELETON. thoracic rib, invites the reason to name all these pieces as costiform, wherefore should Fig. 468. The 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- logues. we not regard the pieces 1,2, 3, 4, 5, con- tinued serially into the rib of 6, as being cos- tiform likewise, despite the fact that anato- mists have already regarded the pieces 1 and 2 as the coracoid and clavicular bones ? Do we not see in Jig. 469. that the parts 1, 2, 3, 4, 5 point to the parts a, b, c, d, 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 a, 1 or b, 2, taken as whole quantities, equal the costo- sternal form f 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 aught else, to regard the cora- Fig. 469. The cervical spine of 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 just as the sternal rib, 6, continues the vertebral rib, f to the sternal median line. coid process of the human scapula as the counterpart of the bone ( d Jig. 466.) called coracoid in the bird, or of 2, the coracoid of Jig. 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 ossepps centre (a rudi- mental representative of the hsemgpophysis), which coalesces with the pleurapophysis in mammalia, and only attains its normal proportions completing the arch with the haemal spine (episternum) 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 scapulary organ is referred to the occipital vertebra, as the haemal arch of this segment of the skull, the scapula is interpreted as its pleurapophysis or rib, and the coracoid bone (process) is accounted the haemapophysis appended to the costiform scapula, and thus the typical occipital vertebra is formed. Although I regal'd the work from which I have quoted to he 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 respecting 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 sleek' tal form and another, still there does appear happily some well-marked limits to the bamo- logies. No one, for example, will torture the bone named scapula into an identity of cast with the bone named rib')' ; and I believe '.hat; 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 th^ chelonian reptile. The coracoid process ol the human scapula is an elemental part propel to the scapula, just as the centrum is a pari proper to the vertebra The bone caliet coracoid (d, Jig. 466.) in the bird abut against that part of the bird’s scapula when the coracoid process usually appears ii mammal scapulae; but this coracoid bone i not representative of the mammal coracoij * He Blainville, Meckel, and Carus entertain thi opinion, which certainly has no support from natur; evidence. f It is true, however, that this very opinion u specting the scapula is advanced by the distil guished author of the “ Homologies,” & c. SKELETON. 647 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- bras ; 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,Jig. 470.) in connection with the cervical rib behind (a), 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 b, 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 the bird) and joining (c) the first sternal piece. Fig. 472. The cervical vertebra, with the rib a, the cora- coids b, 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 parts, 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*, Osteogenie is constant to^he 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 process 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, however, 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 with 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'ogenie est constante, en ce qu’une meme os est toujours a la meme place,” CEuv. d’Hist. Nat. p. 41. T T 4 SKELETON. 648 While clavicles, coracoid bones, and ribs appear identical, we then can readily under- stand how a bird or reptile 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 appear in all skeletal forms.* Prop. XXXV. Marsupial bones, pubic and ischiadic bones, and ribs, are identical parts of the costo-vertebral whole quantities or archetypes. — Wherever we find these parts, viz. sternum, rib, and vertebral 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 costas 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 difform to vertebrre, may disconnect that vertebral series. The same remarks apply to the sternal bodies in front, 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- ally 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 feads 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 cervical vertebrae, 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 specialities 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 ribs, 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, anti aii 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. osseous parts which do not present greater varieties compared to ribs, than ribs do when compared to each other. The law of serial 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. 47 3. 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 (6, Jig. 474.). What is it ? Whence is Fig. 474. The thoracic and ventral median line of the Orni- thorliynchus, Showing the serial homology between the coracoid hones (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 vertebra behind. If m 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 1 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 I marsupial bone (6, 474.) holdswith the line of cost® (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 STON. 649 (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 Jig. 475., representing the continuous series of costiform bodies from the clavicles Fig. 475. The thoracic and ventral median line of the Crocodile (dorsal aspect), Showing the same serial order of the parts named i'afig. 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 pubic 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 (5) 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 fig. 476., the pubic bone (2) occurs op- posite to the sacral vertebral rib (1), and the Fig . 476. The sacral vertebra: and pubic forms of the Crocodiles forming the whole quantity. whole form is thereby completed as the sterno- costo-vertebral-archetypal quantity. The part 2, of fig. 476., may, therefore, as appro- priately be termed a pubic rib as a costitorm pubis. This pubic bone [2, fig. 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 vertebra, 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 vertebrae, such as “ chevron bones” (4, of fig. 477.), be likewise referred to the original whole quantities from which those caudal vertebrae 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 lum- * 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 haj- 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, which I hold respecting it, nor can I believe that any other anatomist will discover the similitude bet ween 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 JDugong, 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 libs 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 I archetype, such as fig. 478., whose costal I Fig. 478. The caudal vertebra of the Dugong, Showing bow 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 vertebras, are bent towards each other and to the median; line, taking the place of the parts 4, 5, then SKELETON. we shall have produced such a vertebra as Jig. 4*77. 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 vertebras 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 651 opinion, the error of which I shall not here stay to point out, if it be not already demonstrated by what I 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 11, 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 Fig. 479. The lumbar region of the Dugong’s skeleton. Showing a serial degradation of the ribs into the chevron bones. 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 fi'om the maxilla to the pubic bones of the abstract archetypal 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 his view over a large number of facts, and to compare these one with another, and sum together all the evidences, making them demonstrate the generalization 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, 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 pah's he terms “ false ribs,” because they are Go2 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 the 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 case, 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 orarchetypal 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, whether 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 conti asthe 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, |l 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. 653 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- typal 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 incontestibly, 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 same way will general com- parison prove that the region which is cervical, or minus the ribs 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 junction 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 tissue 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 “ lines transversae” of the human venter, must be taken as sketches drawn in primordial sub- stance by the hand of nature, indicative of the 'ibs which are wanting at this region of series. Those ribs are proper to the lumbar vertebrae. The linea alba is a sternal trace of archetypal isseous quantity, and is proper to the ribs vhich are now wanting at the mammal venter. The saurian venter, furnished as it is with oth sternum and ribs, and lumbar vertebrae, nust 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 region pre- sents this apparatus degenerated into pri- mordial or fibrous bands. The original of the mammal venter is thoracic, and, as such, 1 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 mammal is equal to that which is persistent at the venter of the saurian ; and thus, in idea, I 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 unity in variety ; that is to say, a whole quantity undergoing a me- tamorphosis of parts. It is this metamor- phosis or subtraction of parts proper to the whole archetypal quantity, which furnishes all the endless sum of variety. 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 mammal 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 fully ascertained by extending the observation through general comparison. In general comparison, we readily discern the ability of creative force 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 submultiple of archetypal uniformity. When I limit my observation to the indi- vidual mammal skeletal form, I find the SKELETON. 054 venter and caudex, Showing the original serial continuity of the ribs and sternal 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 that I cail every sternal apparatus, which happens to he created of lesser dimensions than this space, as a specialty cut from the transcendent line of sternal median uniformity, such as Tfg.480. represents, with the piscean neck ad, the mammal thorax c d, and the reptilian venter and loins e f. Now, the hyoid appa- ratus (a,b,c,d) occurs at the median line of the cervix (a u. Jig. 480) where 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 1 doubt not but that reason must draw the conclusion, that as the ventral sternum (k k) relates the pubic symphysis ( c * d) to the thoracic sternum ( i , i), so does the hyoid sternum as a cervical ster- num (g, h) relate the maxillary symphysis 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 ot' 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 1 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 common and general median line of the mammalian 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 wt 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 mamma, abdomen, and the cricoid, the thyroid, am 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 line 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. Wnat the ventral or the cervical sternal median line 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, fig. 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 vertebras (ab, 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 (b*b*) 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 vertebra behind, they constitute the archetypal series of whole quantities. Prop. XXXVIII. Every fossil skeletal species of extinct animals, as cvell 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 all 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, tha): 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 anatomical science should marvel at the length of a plesiosaure neck as an extraordinary fact “ dug out of the bowels of the harmless earth,” however bizarre a creation this skeletal form mayr 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 Ichthyo- 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 contemplate 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 craniofacial appara- tus consists, like the thoracic apparatus , of 656 SKELETON. variable proportionals of the sterno-costo-vcrte- bral quantities. — The connection which exists between the cranial and the facial structures is quite as intimate as the connection which exists between dorsal vertebras 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 cephalic 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 proceed 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, secondly, 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-vertebral 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 played 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 unproven grounds, to de- monstrate that which had existence no where save in the imagination. An ill-defined sha • dowy resemblance was first seen to have ex- istence between cranial and spinal vertebral forms, and in pursuance of this idea has arisen all that vagrant and bizarre imagery * Almost all the anatomists of the French and German schools differ in opinion as to the number of modified vertebra 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 facial 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; Cuviei', three ; Geoffrey, seven ; Carus, three (Lehrbuch der Zootomie) ; Meckel, three (Beitrage zur verglei- chenden Anatomie, Band 11. S. 74.) ; Bojanus ad- mits four, and Burdach only three. Professor Owen enumerates four in the fish, 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. My present limits confine me to the observation of nature, ami 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- lope of the cerebral mass and the osseous j, coverings of the spinal chord, is now a fixed and immoveable fact in anatomical science. But though the existence of this homoiogy is now undeniable, still I may remark that every observation which serves to prove something further in respect to spinal verte- brae, 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 vertebra. Every new fact, established upon the com- parison of spinal vertebrae, must be new aiso in regard to cranial vertebrae ; and this is the * Oken is generally acknowledged as the signal j] discoverer of the homology between cranial and spinal segments. He believed that the cranial struc- 1 tures were repetitions of the osseous quantities pro- ij per to the cervical vertebra. It is said by some;; anatomists with Meckel, that Frank first recognised]] this analogy between the skull and the vertebral (Sammlimg Auserlesener Abhaudlungen, Band XV. S. 267.). Burdin supposed the head to be a com- plicated vertebra (Cours d’Etudes Mddicales, Baris, 1803, vol. i. p. 16.). Keilmeyer believed the same.i Next Geoffrey St. Hilaire, Dumeril, and Goethe ex- tended the theory, making such observations as art at present considered to be purely hypothetical, and little better than fanciful vagaries which almost1 overshadow the first truth. The similitude drawn by Goethe between the facial bones and the ver- tebra, is scarcely less absurd than the likeness which; Oken and Spix are supposed to have seen between] the temporal styloid process and the sacrum, or, between the hyoid apparatus and the pelvis. Hence it is not to be wondered at why Cuvier mocked tin cranial vertebral theory, when we find Spix seeking for a repetition of the regions of the trunk of tin body in the head ; and, because lie would bend na- ture to his wild unstable fancy, whether she wenS willing or otherwise, so we have him representing1 tlie pelvis in the temporal bone ; and likening tin1 hind limbs to the lower maxilla ; the auditory ossi. cles to the pubis ; the maxillary condyle to tin femur ; tire coronoid process to the tibia, &c. &c See Cephalogenesis, seu Capitis ossei Structural For Oken’s views of this subject, see Jsis, 1820 No. 6. p. 552. ; Escpxisse d’un Systeme d’Anatomi de Physiol. &c., Paris, 1821, p. 41. ; alsoUeberdi Bedeutung der Schadelknochen, Jena, 1817. SKELETON. 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 1 have named archetype, and compared with it I have shown that all other spinal vertebrae 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 this rib makes an integral part of all vertebrae — of all those, at least, which possess a certain ]uantitative character. It must have already appeared evident to he reader that it was premature to have ;ought to establish an identity between cranial md spinal segments, without having first iscertained the quantitative nature of the jhing which was named vertebra. For as it vas evident that something was yet to be iroved by the comparison of spinal vertebrae, o therefore it was not possible to prove all hat might be known of cranial vertebrae, vhile prematurely referring one unknown uantity to another equally unknown — I lean the spinal vertebra to the cranial verte- ra. Since it was by no means as yet demon- trated that the form which anatomists recog- ised as the spinal vertebra was a quantity of xed and invariable character, how then could be proved that the form to which it was kened in the cranium was of fixed and un- tying dimensions ? When anatomical science, lighted by the irch of Oken’s genius, first pierced the mist id obscuring cloud of nomenclature, which '.‘scribed the cranial structures as distinct pm the spinal forms, and when it expounded e facts and doctrine of that radical homo- fey caste which related both classes of fucture together under the common name jrtebrse, it did not in truth progress much arer to the explanation of the law of form an when it first explained, despite of no- mclature, the analogy which existed between VOL. IV. 657 sacral bones and lumbar vertebra. In the one case it only related hitherto unknown forms to vertebrae, without knowing the typi- cal form of vertebrae 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 archetj'pe or whole quantity. The facial apparatus is to the cranial forms just what the thoracic cost* 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 resemblance, as well between costal forms and maxillary forms, as other anatomists have recognised between cranial forms and spinal vertebrae. The identity which is already proved to exist between the latter must prove the identity of the former likewise. The homology of caste which d priori reasoning establishes between cranial and spinal forms, will 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 vertebra, so must we, I contend, be induced to name the maxillas of cranial vertebrae to be the homo- logues of the costae of spinal vertebrae (even if 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 vertebra, 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 much 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, while we see that the latter are always attended with * If the facial be to the cranial structures just what the thoracic costa? are to the dorsal vertebra, then it will appear evident to the reader that, when Oken, or Spix, or Goethe, or Geoffroy 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 vertebral pieces. Schultz (De Primordiis Systematis 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 pieces. 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 vertebra. U V <3.58 SKELETON. the ribs, then the cranial vertebrae, as verte- brae, must have the ribs also. What other cephalic structures, therefore, are there in the head which may be said to stand as the ribs of cranial vertebrae, if these ribs be not the maxillary arches ? * Now there happens in Jig. 481., between the costiform maxilla (dd*) and thoracic ribs Fig. 481. Showing that the hyoid apparatus relates to the cervical vertebra;, and the facial apparatus to the cranial vertebras, just as the thoracic or costo-sternal apparatus relates to the dorsal vertebra;. ( pp *), that hiatus or gap in costal series (q q q) which interrupts the idea of a eo which is called the cervix, and it is this hiatus tinuous serial costal order ; at the same til * In the “ Homologies,” the author names the maxillae the “inverted arches” of the cranial ver- tebrae. These inverted arches answer to the hsema- pophyses of the author’s ideal typical vertebra, and not to the pleurapophysial elements (the ribs_) of that ideal form. 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 evidently some mystery about this ideal typical vertebra figured in the “ Homo- logies,” which I cannot penetrate, and for this reason, viz. that I find the author’s “ ideal typical vertebra,” while compared to the osseous segmi taken from the bird’s thorax, and which he ter: the “ natural typical vertebra,” does not correspo quantitatively. In this ideal form I find the r ( pleurapophyses) but as mere rudiments, whilst the natural form I see that these ribs embrace tl racic space from the spine nearly to the sternU| Again, in the ideal form the hsemapophyses lm appended to the vertebral centrum ; whereas in 1 natural typical form they articulate with the ills ends of the thoracic ribs. SKELETON. 659 that vertebral series (g, h, i, k, l, m, n) is still uninterrupted as it passes from dorsal ver- tebras (p), through cervical vertebrae, to cra- nial vertebrae (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, h, l, m, n ) are developed upon each of the cervical vertebrae. If the original plus ribs of the cervical vertebrae still persisted at the lines q q q, 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 cost® below is the hyoid apparatus ( f*>g *, &*). 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 q q 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 ban cranial vertebrae do to spinal vertebrae ; md if we see little reason to doubt the iden- ity between the latter structures, there is, as t seems to me, even still less reason to doubt he homology or correspondence between the wo former. In Jig. 481. I have indicated the number of hose vertebral forms which constitute the uman cranium, taking as my guide the in- ariable attendance of the costal structure pon the vertebral structure, as well in the ead as in all other regions of the spinal tis. The first dorsal vertebra (p) is attended v the plus ribs (pp*), stretching over tho- icic space from the back to the sternum. 11 the cervical vertebrae (n, m, l, k, i, h, g) e likewise attended by the minus costae 1’, m, l, k, i, h, g). From these severally I tve produced lines to the hyoid apparatus, |id these lines, together with the hyoid sees, indicate thoracic costo-sternal quan- y, which metamorphosis has degraded down the quantities at present forming the cervi- 1 region. The intervals between the cervi- lines of the original costae are marked and the thing, though absent, may be still visible to the mental although in- visible to the physical eye. For the knowledge of the thing absent, viz. some of the digits of e ,Jig. 483., is, I con- tend, equal to the knowledge derivable from the actual presence of the very same quan- tity, viz. those digits in a ; and, therefore, so long as I know the quantity which is absent from one ens to be the same as the quantity which is present to another ens, this must furnish me with the idea of equality, or the uniformity, as saliently as if the quantity were f resent for both enses. When, for example, compare the soliped or the cloven foot with the human hand, I find that the lesser ens is contained in the greater ens, and that the other parts, which are wanting to the lesser, are still manifest in the greater ; there- fore I conclude, that as the greater, viz. the human hand, can undergo a metamorphosis or subtraction of parts, so as to reduce it to the proportions of the cloven or the soliped organ successively, so has the original or plus quantity, which may be regarded as equal to the human hand, undergone a metamorphosis of parts in such degree as now yields for our contemplation the special or minus quantities, which we name cloven or soliped foot. Prop. XLI. The scapulary and pelvic mem- bers are homologous. — In a former place I have given reasons why we should consider the clavicles, the pubic, and ischiadic bones as the homologues of ribs ; and therefore 1 shall not need their presence in this place while holding comparison between the fore and hind members.* The fore-limb (Jig. 485. a.) separated from the clavicle, consists, like the hind limb (e), separated from the pubisand ischium, ofafixed and invariable number of segments; and the parts which constitute these segments in both are absolutely corresponding. The scapula (a) corresponds to the ilium (e) ; the hu- merus (b) to the femur (f) ; the radius (d) to the tibia (h) ; the ulna(c) to the fibula (g). The hand is manifestly the counterpart of the foot. The carpus represents the tarsus ; the metacarpus corresponds to the metatarsus ; the phalanges of the hand are represented in the phalanges of the foot. The pisiform bone (rf) of the carpus is similar to the os calcis ( q ) of the tarsus ; the great toe represents the thumb ; the little toe simulates the little finger. The common structural identity be- tween both organs is plainly manifest at al points save one ; and this, though often at- tempted to be explained, has not as yei yielded up its mystery. How happens i that the patella (hi) and fore aspect of tin hind limb (e), corresponds to the olecranoi (h) and back of thefore-limb(A)? I believe that the complete solution of this problem may bi had from the following remarks made ii reference to Jig. 485. On comparing the right scapulary orgai| (a, b, c, d) with the left pelvic membe (e, f, g, h), I find that the fore aspect of til- former does not correspond to the fore aspec of the latter ; but when I compare the bad] of the arm a, b*, c*, d* with the front of th lower member (e, f, g, h), their correspond * Yicq d’Azyr regarded the coracoid and acroraio processes of the scapula as representing the pubi and ischiadic bones, while Cruveilhier states it '< his opinion that the spine and acromion process the scapula has no part analogous to them in th ilium. Professor Owen considers the clavicle as th homologue of the os pubis, agreeing in this vie;, with Cruveilhier. But, according to Professi Owen’s views, it is not with the rib that either tf clavicle os pubis or ischium manifests an homology1 on the contrary, he regards the iliac bone and tl scapula as the true representatives of the ribs — bJ pleurapophysial elements. SKELETON. 665 ence is at once manifested ; for then we have the olecranon process ( 'h ) of the ulnae* in the exact position of the patella ( h ) of the lower member (e). Moreover, in this new position of the scapulary organ (b*, c*, d*), we find that the position of the bones ge- nerally correspond with those of the pelvic organ (e, f, g, h) ; for the radius (d*) is now Fig. 485. A, The right scapulary member, and E, the le ft pelvic member of the human skeleton, compared ; and showing how a torsion in the shaft of the humerus differences loth limbs. internal to the ulna (c*), just as the tibia (h) is internal to the fibula (g) ; while the back of the hand ( n,m,p , o ) of the member b*, c*, d*, corresponds now to the dorsum of the foot ( n,m,p,o ) of the member f,g,h, and the thumb (°) of the member c*, d* is now laid opposite to the great toe (p) of the member (g, h). Now, I also find that the back of the lower member (f*, g*, h*) represents the front of the upper limb (b, c, d), and that on com- paring f*, G*, h, in its present position, with b, c, d, the constituent bones of both organs correspond ; for now the ulna (c), being in- ternal to the radius (d), is exactly simulated, by the fibula (g*) being internal to the tibia (h*). Moreover, the palm of the hand (m, 71, o, p) of the limb (b, c, d) is now turned for- wards, like the sole of the foot (m, n, o, p of 066 SKELETON. g*, h*), while the pisiform bone ( q ) of the hand corresponds in position to the os calcis ( g (fig- 4-88.) When the ventral ray (3, 2, 1) of the arche- type (Jig. 487.) widens to the costal arch c, c in Jig. 488., this arch is left standing at the thorax of some animals, and even at the ven- ter of others. As Jig. 488. stands in its pre- sent quantitative character, it may be found in the abdomen of fishes still having the parts 1 and 2 attached and persisting, or obliterated and lost to the original quantity, as the case may require. At the dorsal aspect of the spinal axes of all terrestrial animals it may be understood that the parts 1 and 2 of Jig. 488. are lost or subtracted. It is the ventral ray, consisting of the parts 7, 8, 9 (Jig. 488), which suffers median cleavage and widens into the costal arches (c, c). As a certain proof of this fact, I may remark, that where the full ventral ray persists as at 7, 8, 9, there we never find the full costal arches (c, c) existing; and where these latter are existing, there we never find the ventral ray. As the one becomes converted into the other, it is hence impossible for the same ens to exhibit both conditions of form at one and the same time. When the ventral ray 7, 8, 9 (Jig. 488.) has widened into the costal arches, these arches may and do suffer a metamorphosis of quan- tity to the same degree as w hen in their ori- ginal azygos condition. Thus the ribs (c, c ) become symmetrically proportioned or oblite- rated successively at the points f e , d, by imaginary lines radiating from the sternal centre at 9. When these costal arches (c, c ) meet at the central point 9, then we name the ribs sternal ; when they fall short of this point 9, either at the point f or e, we name these ribs asternal; when they become ob- literated as far back as the point d, then we name them, as in the lumbar spine, the trans- verse processes. As every law in nature is phaseal and gra- duated, so is this the distinguishing character of the law of formation. The ventral ray (7, 8, 9), after undergoing a cleavage into symmetrical halves, will present, in various classes and species of animals, a phaseal gra- dation in the process of widening, and assume the form of the arc a, b, and c, successively', according to necessity. In the caudex of the saurian or cetacean, we find vertebrae producing at the same time the neural arch and spine, the haemal arch and spine, together with the costal process (c, c), jutting laterally from the centrum (3) as far as the point d ; when this is the case, then the haemal arch and spine is fashioned of that quantity of the costae which intervenes between d and f and which, being severed from c at the point d, is bent inwards towards the median line 6, 7, thus assuming a second time its azygos position. In some aquatic mammalia (the porpoise, dolphin, &c.) there remains at the dorsal aspect some trace of the dorsal form (1, 2, 3, of Jig. 488.). The ceta- cean dorsal fin is thus explained. Prop. XLI1I. The scapulary and pelvic pairs of limbs are proportional quantities meta- morphosed from the dorso-ventral archetypes. — The scapula disconnected from the clavicle is the quantitative counterpart of the iliac bone separated from the os pubis and ischium. Having in a former place remarked upon the structural homology which relates clavicles, pubic bones, and ischiadic bones to ribs ; and having also pointed out the homological rela- tions between the scapulae and the iliac bones, we shall in this place first consider the struc- tural homology between these latter osseous quantities and the vertebrae, and next the homological relations between the fore and hind limbs, the ribs, and the dorso-ventral rays. The dorsal vertebra, viewed from behind, is represented in A (Jig. 489.). b represents the dorsal aspect of the two scapulae conjoined, and c represents the two iliac bones placed base to base. Is there a structural identity apparent between these three figures ? and in what points of character do they correspond? To this question I answer in almost all points ; for not only do these forms, viewed in their entirety, correspond, but even their mode of genesis is identical. The vertebra (a) is a symmetrical form, consisting of opposite laminae (c, c), which 670 SKELETON. join each other at the common median line (a, b). From these lamina; we find jutting out laterally the exogenous transverse pro- cesses (d, d), each of which is tipped by an epiphysis. The pair of scapulae (e) forms asymmetrical figure : both scapulae (c, c ) are evidently similar to each other, and also to the laminae (c, c) of the vertebra (a).* From each sca- pula we find projecting laterally an exogenous rig. 489. Showing that the pair of scapula; and the pair of iliac bones, compared with the pair of vertebral lamimc, prove a homological relation, and also that the heads of the humerus, the femur4, and the rib are similar to one another. process (d, d ), which is commonly named acromial process, and each is tipped with an epiphysis also. These acromial processes evidently correspond to the transverse pro- cesses (d, d) of the vertebra (a). The pair of iliac bones (c) likewise forms a symmetrical figure when laid crest to crest. These two iliac bones (, c), which sketch out the form of the original ventral ribs proper to the lumbar vertebra ; and it will be seen that a, b, c hold series with (d) the pubic bone, and (e) the ischiadic bone. Between a, b, c, as the ventral ribs, occur the intercostal spaces iff), and be- tween the pubic and ischiadic bones (d, e) occurs that space (/) which, in human ana- tomy, is named “ thyroid foramen.” Is not this thyroid foramen an intercostal space, if d ande be costae proper to the sacral vertebrae ? And do not the pubic and ischiadic sym- phises at the point k correspond to the linea alba (/, /), which stretches between the pubis and sternum ? Iuj%- u. we find the scapula (k, k, h, i ) oc- cupying, at this region of series, a position similar to that which the iliac bone holds elsewhere. But beneath the scapula the ribs (2, 3, 4), for obvious purposes, persist ; while oeneath the iliac bone they are wanting. This want ot the ribs beneath the iliac bone, and his presence of the ribs beneath the scapula, institute the difference. It those portions of the ribs (b and c of %"• b.) which lie beneath the scapula suffered netamorphosis, then b and c would abut upon he glenoid cavity h, and would be to the capula what the pubic and ischiadic costiform mnes are to the ilium ; and then we should iave, between b and c of fig. b., the inter- ostal space/, as corresponding to the thyroid perture. It is the costiform clavicle (a of b) Iiich becomes severed by the scapula from s vertebra behind, just as the costiform os ubis is severed by the iliac bone from its ver- ■bral quantity. The cotyloid cavity (g of a) is formed by ie junction of three bones, viz. the ilium 1 ")> jhe os pubis (d), and the ischium (e) ; it it is the iliac facet of the cotyloid cavity Inch alone corresponds to the glenoid cavity the scapula. It the ribs (b or c of Jig. b.) ippened to be dissevered from their vertebrae •hind by an interval equal to the size of the apula (k, k, h), and if these sternal ends of e ribs (b, c) then joined themselves to the ;noid articular surface (/;) of the scapula, is three bones (h, b, and c) would also form cotyloid cavity for the head of the humerus. In those animals (birds, reptiles, &e.), where VOL. IV. two clavicles are required to be metamor- phosed from ribs, they illustrate still further the structural analogy which exists between them and the ischiadic and pubic bones, which latter exhibit, in relation to the ilium, the same character that the clavicles manifest in relation to the scapula. In fig. a. the os penis (/*) will be seen to fall behind the symphisis pubis, while in fig. b. the episternal ossicles (/*) will be noticed as producing the sternal median line forwards into the neck. At the subpubic region, where l * occurs, and at the episternal region, where the episternal ossicles occasionally appear, the sternal median line is bounded in the animal ; but in the comparative abstract animal, these points may be regarded as unfinished. Prop. XL IV. The craniofacial apparatus of segments are proportionals of the dorso-ventral archetypes. — If it be true that the vertebral quantity is a proportional of the sterno-costo- vertebral quantity, and this latter a propor- tional of the dorso-ventral archetype, then it must follow that the cranio-facial apparatus, which appeal s to bear a structural homology with the sterno-costo-vertebral quantities, is also constituted of segments which, like these latter, are proportionals of the archetypal quantities. Even though the whole animal kingdom did not present us with a skeletal form, upon whose cranium the dorsal rays persisted complete, still the above-mentioned inference may be legitimately drawn ; but when, amongst the class of osseous fishes, we find fig. 492., upon whose cranium the dor- sal rays actually persist, then the a priori and the d posteriori trains of reasoning meet and answer to each other, while standing in pre- sence of the fact itself, as nature produces it. In fig. 492. we see that the archetypal dorso-ventral quantities ( a,b,c,d ) are conti- nued into the head, not only by their centra, their costal inferior arches, and their dorsal laminae, which form the neural arches from 17 to 1, but also by their dorsal interspinous os- sicles from in to n, and by their dorsal palms from o to p. The head of the osseous fish (fig. 492.) of the class Pleuronectida; may be accounted, therefore, as constituted of a series of the dorso-ventral archetypes specially modified. Between the cranial and the facial structures is continued the line of spinal centra ; and from these, as from the centra elsewhere throughout spinal series, the dorsal and the ventral rays project. The inferior cranial rays are the jaw-bones (c f. h h) and hyoid arches (g, g) ; the superior cranial rays are the forms o p, m n. Prop. XLV. The cranio-facial apparatus is the origin of the dorso-ventral archetypal series, and the caudal apparatus is its termination. — In the same animal, whose cranial structures are still crested by the dorsal rays complete, we find the opposite caudal extreme (figA93.) also crested by similar rays, dorsad as well as ventrad. The spinal centra (n, m, l — a) still produce the entire rays (o, q ) above and be- low, while the terminal centrum (a) stands as x x 674 SKELETON. a nucleus, around which are arranged, in pal- zontal ray (9), fashion the fan-shaped caudal fin. mate order, the rays of nine archetypes, which. This caudal fin, whose rays describe the arc bending towards each other, and to the hori- p q, is composed of the palms of nine arche- Fig. 492. The craniofacial apparatus of the osseous fish ( Pleuronectidee ), Indicating the metamorphosis of twelve or more spinal quantities in its composition. types, radiating from the common centre (a). The nine inferior palms are those which num- ber from 17 to the palm 9 ; and the nine supe- rior palms are those which number from 1 to the palm 9; while the azygos palm 9 may be regarded as composed of the dorsal and ven- tral palms of the last archetype bent towards each other, and becoming in the horizontal line fused together. The bones (o, p, q), are the counterparts of the neural and haemal laminar arches, assuming the same palmate order as the palms. The head {Jig. 492.) and the caudex {Jig. 493.) constitute the origin and termination of spinal series, and are ex- amples of special modifications exercised upon the original archetypal quantities. Prop. XLVI. The uniform archetypal se- ries undergoes a graduated metamorphosis of its quantities for the production of all varieties of skeletal species.— In fig. 494. I represent the archetypal series of the dorso-ventral quanti- ties constituting the uniformity, forasmuch as all the segments are plus and quantitatively equal. The segment 1 is equal to the segment 38, and to all the intervening segments. This uniform series of quantities appears finite, like the right line (c d) which passes through its centre; but as the right line itself is but a part or proportional of that ideal lin> which is infinite or boundless, so of the seriei of archetypal quantities, numbering in tin figure from 1 to 38 ; for this series may liki number be produced to infinity in imagina tion. In the serial line {fig. 494.) which if com posed of 38 archetypal dorso-ventral quantij ties, we do not as yet distinguish any specie, differences ; and this is owing to the fact tha all the quantities composing the series are sim; lar or homologous ; neither can we discove any reason why we should name cither of th extremes of this serial line (d c) as the orig! or the termination in preference to the otha extreme, for the segment 38 is equal to tl segment 1 and hence it matters nothing t the entities themselves at which end of tl series we commence the enumeration, 1 nature there is no instance of a skeletal ax constituted of such a uniform serial line quantities as those of Jig. 494., but yet it possible to prove that every skeletal axis part of such an original series. That skelet axis which approaches nearest to the abs lutely uniform condition of Jig. 494. is to I found amongst the class Pisces. The skeletal fabrics of all animals are syr SKELETON 67 b bolic of that sphere in Nature in which they those of aquatic and terrestrial animals. The are destined to live and act. The two main aquatic class, inhabiting the watery regions, primary divisions of differential forms are symbolise their native element, in which Fig. 493. The caudal apparatus of the osseous fish ( Pleuronectidce ). hey move submerged ; and accordingly we prone upon the earth, produce the locomotive nd them treading this medium by loco- organs suited to that motion, viz. on the lotive members arranged dorsad as well as ventral side onl}\ entrad ; while the terrestrial class, moving All species of the class of fishes approach Fig. 494. 676 SKELETON. of the dorsal fin, since they are denizens of the world of waters. The tribe of fishes known as Pleuronectidae is bordered dorsad as well as ventrad by the locomotive palm- organs, and therefore they simulate the series of fig. 494. more closely than any other class of animals. The Pleuronectidae are the most archetypal class of animals in Nature ; for the first step of the law of formation in the meta- morphosis of fig. 494. is to create a cephalic end (fig. 492.) and a caudal end (fig. 493.) to this series of whole quantities, by a modifica- tion of a certain number of the archetypes at either end ; and thus the animal of the class Pleuronectidae is fashioned, having the con- tinuous palmed or fin-organ still persisting dorsad and ventrad on those spinal arche- types which stand in series between the cephalic and caudal extremes. The structural composition of the head will vary according to the number of those serial archetypes which suffer metamorphosis for its creation. For if we suppose that the six quantities which are included within the circle a c R (fig. 494.) should be subjected to cephalic metamorphosis, we still can assign no reason why Nature should limit herself to the number si. r, or any other number, if ne- cessity required the metamorphosis of agreater number for one species of cephalic apparatus and a less number for another. Although in a former place I have numbered six segments as proper to the composition of the human head, still I am by no means of opinion that Nature limits herself to number six in the creation of all other species of cephalic appa- ratus ; on the contrary, 1 shall not hesitate to assert it as a fact, that (fig. 49:1.) the head of the plaice may be taken as an instance in which fourteen dorso-ventral archetypes have suffered cephalic modification.* The alternate fin-organs at the back and venter occur by the alternate metamorphosis of certain members of the palms of the conti- nuous series of archetypal quantities. In the Pleuronectidae, the dorsal and ventral palmed fins are continuous for the entire length of the spinal axis, as in fig. 494. ; but in other classes of fishes we find the fins occurring isolated at certain regions of the spinal axis: such, for example, as the fins called dorsal, jugular, abdominal, anal, and caudal; and this alternation may be explained by referring to fig. 494. If the palms which I have included in the semicircles k i,, m n happen to be metamorphosed or subtracted, then the iso- lated dorsal fin (m o l) will remain as we find it presenting in many of the class Pisces, and even in some of the cetaceans. The fin- * Professor Owen enumerates four vertebral seg- ments as composing the heads of all animals of the four classes. For my own part, I see no reason to entertain the opinion that Nature limits herself to a fixed number in the segments of the head, any more than she does in constructing the cervix, the thorax the loins, the sacrum, or the caudal region of the spinal axes. Cams and Oken speak of the number Jive, as though Nature limited the operation of her law in patronage to this magical quinque in vertebrate creation. organ is composed in all cases of a plura number of palms; the number always corre sponding to the dorsal rays of the archetypes The palm is a hand, while the fin presents ai a series of hands. When the series of archetypal quantitie; suffers metamorphosis at certain lines whicl the creative hand of Nature draws through it the animal design or species is struck oui accordingly. When all quantity lying externa to the converging lines o it, p it undergoes metamorphosis or subtraction, then the series of quantities which happens within these lines will exhibit the condition of proportional am progressional quantities, such as we fine standing in the caudal region of many animals When Nature draws the right line a b througl this region of the serial archetypes, and at tin same time metamorphoses all quantity afiovi or dorsad to this line, she creates the dorsa region of the spinal axis of all terrestria animals, to which are remaining those part which we name the neural arches, sufficien for the protection of the spinal cord. The quantity which occurs within the line a B, f g answers to the thoracic ophidiai skeletal axis, whose ventral or opposite cost; arches occur by a bicleavage of the azygc ventral rays. The thoracic series of eac skeletal axis is formed after the same manne as that of the ophidian. The numeric; length of every thorax varies according to tli number of those serial archetypes of fig. 49 which suffers thoracic metamorphosis ; an! its position in spinal series varies also ai cording to the numerical position of thol archetypes which undergo a thoracic modi! cation ; for if they be the segments whit' hold serial order between that which numbej (in fig. 494.) as 13, and that which numbers 3|j then the thoracic length will correspond these numerical segments. When the head is fashioned of the s quantities included in the circle q c r, whi the neck is proportioned by the line e d, fro six, or seven, or more of those quantiti which succeed the head, viz. those seginei between 7 and 14, 15, or 16, then the ne will number accordingly ; and when the tlior is to succeed the cervix, then the twelve more segments which succeed those of t. cervix are proportioned thoracically by f lines f g. When, lastly, the lumbar, saci and caudal regions are to succeed the thorj it is the line F d which gives to these regie]1 their several quantitative characters. The law of “unity in variety” appeji therefore to be plainly demonstrable as archetypal plus series of quantities, undergo!' a graduated metamorphosis ; and if, by ; order of the foregoing remarks, I have t upon the reader’s mind the idea that the pi- portional variety constitutes the species ol d form of skeleton compared to another, anejf all others of the lour classes of vertebi'f animals, then my object has been attained) the course of argument which 1 havepursu (Joseph Maclise. SLEEP. 677 SLEEP. — This term is employed to desig- nate that state of suspension of the sensory and motor functions, which appears to alternate, in all animals, with the active condition of those functions, and which may be made to give place to it by the agency of appropriate impressions upon the sensory nerves. Although this may seem a complex de- finition of a state which seems to be in itself so simple, yet it will not be found easy to alter its character without rendering it less stringent. We more especially desire to ex- clude from it the abnormal condition of coma , in all its forms ; whether resulting from the influence of pressure or effusion within the cranium, or consequent upon the poisoning of the blood by narcotic substances, or occurring as part of that inexplicable series of phenomena which are termed hysterical. The state of coma, where not so intense as to affect the movements of respiration and deglutition, is identical with profound sleep as regards its obvious manifestations ; but there is this im- portant difference, that simple sleep may be made to give place to activity by the ap- plication of appropriate stimuli to the sen- sorial system ; whilst in complete coma, no impressions on the sensory nerves have any dower of bringing back the consciousness. Between these two conditions, however, every ;radation may be seen ; as in the heavy sleep iroduced by an over-dose of a narcotic, in in- omplete hysteric coma, or in the torpor fesulting from slow effusion within the cra- jiium. The necessity for sleep seems to arise from he fact, that the exercise of the animal junctions is in itself destructive of the sub- tance of the organs which minister to them ; o that, if the waste or disintegration pro- uced by their activity be not duly repaired, ley speedily become incapacitated for further se. This doctrine is now' so generally ad- litted, that it does not seem requisite to Iduce proofs in its support. The substance f muscles is regenerated during the sus- msion of their action in simple repose ; and is not essential that, for this purpose, a state unconsciousness should intervene. As e substance of the nervous centres and unks, more especially the former, under- •es a similar disintegration as a necessary ^sequence of its activity, this too requires period of repose for its regeneration ; but e repose, or suspension of functional acti- y, of the sensorial portion of the nervous stem, necessarily involves unconsciousness ; d it appears to be on the nutritive regene- yon which takes place during true sleep, pt its refreshing power depends. No such reshment is experienced from the uncon- ousness of coma, however prolonged ; and '-’re are some forms of ordinary slumber in '"ich it is more or less deficient. The or- f lie functions are not affected in any con- -erable degree by the suspension of the sen- 5 ial ; for we find that not only are the ( nations in which these functions essentially c isist uninterruptedly carried on, but that the muscles, nerves, and nervous centres also which are concerned in maintaining them, are enabled to sustain an unintermitted action. Thus the movements of the heart are not, in warm-blooded animals at least, normally suspended, from the first development of that organ until the close of life ; the respiratory motions, in like manner, are kept up uninter- ruptedly from birth to death ; and the pro- pulsion of food along the alimentary canal during sleep by the peristaltic contraction of its muscular coat, the sustained action of the sphincters, the peculiar position of the eyes, and the active state of the extensor muscles of the legs in animals which sleep standing, are additional evidences that the state of con- tinuous repose is not required for the reno- vation of the powers of certain parts of the nervous and muscular apparatus. To use Dr. Marshall Hall’s phraseology, “ the true spinal system never sleeps and, whatever we may think of the existence of his “ true spinal ” system of nerve-fibres, as distinct from those which minister to the functions of the ence- phalon, there can be no longer any doubt that the ganglionic portion of the spinal cord is a distinct centre of nervous action, which re- tains its power of actively responding to im- pressions made upon it, during the profoundest repose of the other centres ; whilst, from the complete suspension of its functions, even for a very brief period, death inevitably results. In following out our inquiry into the nature of sleep, and of certain conditions allied to it, we shall find it convenient to regard the encephalon as composed of four leading or primary divisions : 1. The medulla oblongata, which essentially consists of a prolongation of the spinal cord, including the centres of respiration and deglutition ; and also having incorporated with it, without properly form- ing part of it, the ganglia of hearing and of taste ; 2. The ganglia of sensation, including, with the olfactive, optic, auditory', and gus- tative centres, the corpora striata and thalami optici, which are probably', when taken to- gether, to be regarded as the ganglia of tac- tile sensation*: 3. The hemispheric ganglia (trolly), or peripheral portion of the cerebral hemispheres: and 4. The cerebellum. The^rrfof these divisions really belongs to the spinal cord, and, like it, is constantly active — The second appears collectively to form the true sensorium , to which external impressions must be conveyed, in order that they may be felt (each class of sensations being received through the medium of its own ganglion), and from which proceeds the stimulus to those automatic movements which can only' be excited by a sensation. Such are the truly instinctive actions. — The third division, of which scarcely a rudiment exists in the lowest fishes, although it constitutes by far the largest proportion of the encephalon in man, seems to be the instrument through which ideas are generated, by' which they are retained and made the subjects of intellectual * See British and Foreign Medical Review, vol. xxii. p. 510. x x 3 078 SLEEP. processes, and by which voluntary determina- tions are formed. Impressions made upon the organs of sense would seem only able to act on the hemispheric ganglia through the medium of the sensorium ; whilst the volun- tary determinations, resultingfrom the exercise of the reasoning powers, can only act on the muscular system by the transmission of a downward impulse from the hemispheric ganglia to the automatic centres, in which the motor nerves originate. If this be a true representation, the ordi- nary phenomena of sleep are not difficult of comprehension. The state consists essentially in suspended activity of the sensorium, so that impressions made on the organs of sense are neither felt nor perceived, — that is, neither excite sensations, nor give rise to ideas. In like manner, those automatic move- ments which are dependent upon sensations for their excitement are suspended; and as the tor- por of the sensorium cuts off the functional connection between the hemispheric ganglia and the muscles, the latter cannot be called into activity by any mental operations in which the former may be concerned. In or- dinary profound sleep, the hemispheric ganglia would seem to be in the same passive con- dition as the sensorium itself ; so that all mental activity is suspended. In dreaming, however, there is a train of ideas, called up by the laws of association, and not regulated by any voluntary control, bespeaking a partial activity of the hemispheric ganglia. Into the conditions of this phenomenon we shall inquire hereafter ; at present only ob- serving, that if the sleep be deep, external impressions are as completely unperceived by the dreamer, as they' are in a state of entire unconsciousness ; and that, in like manner, the strongest desire felt by the dreamer to perform certain bodily movements, even when he fancies that his life depends upon them, is as ineffectual as if he were suffering from a total paralysis. If external impressions are in any degree felt by the dreamer, or his volition can exert its power over the move- ments of his body, the sleep is not profound, but rather approximates towards the state of somnambulism or sleep-waking, in which the sensorial as well as the hemispheric ganglia are in a condition of partial activity. The state of simple sleep, again, is allied to that of hibernation (see Hibernation) ; the difference between them being essentially this, that in the latter condition, besides the profound torpor of the sensorial centres, there is a great diminution or complete sus- pension of the activity of the organic functions. We may trace, in fact, every gradation be- tween the simple repose of the sensorial cen- tres, in which the state of sleep essentially consists, to that complete suspension of all the functions of life, which is of ordinary oc- currence, during the winter season, in cold- blooded animals. Many of these can even en- dure the freezing process without the loss of their vitality ; their activity being restored by the renewal of warmth. Next to this is the condition of those hibernating mammalia, which pass the winter in a state of uninter- rupted torpor, and in which the organic func- tions seem reduced to their lowest possible amount of activity, short of entire stagnation. This reduction is manifested in the slowness of the circulation, the infrequency of the respira- tory movements, the low degree of heat sus- tained, the abatement of the demand for food, and the small amount of carbonic acid, urea, and other excretory products, set free daring the persistence of the hibernating state. But there are other hibernating mammals, in which the reduction is less decided, and the torpor less profound ; these animals awaking from their repose at long intervals, taking food from the store which they have prepared, and again relapsing into inactivity. And there are others, again, in which it differs but little from ordinary profound sleep, except that the pro- portion of time passed in the waking state is much less than usual. Further, it is a curious ;] observation of Dr. M. Hall’s (loc. cit.), that the ordinary diurnal sleep of certain hibernating mammalia presents, in the reduced activity of the organic functions, an approach to the tor- por of their winter state. Sleep of Plants. — The complete suspen- sion of the organic as well as of the animal functions during the hibernation of cold- blooded animals corresponds with what lias been termed the winter steep of plants. But plants have also what has been called a diurnal sleep ; and although it is obvious that plants can present no phenomena really ana- logous to those in which we have defined tilt- sleep of animals to consist, yet there are pe- riodical changes in the condition of their leaves! and flowers which are deserving of consider-'J ation under this head, especially as affording] ing an additional indication that even in the; functions of organic life there is a tendency to a] more or less decided alternation of activity andi quiescence. The parts of plants which exhibit the changes in question, are the leaves and the flowers . In the former we frequently notice an entire difference in the nocturnal and di-i urnal aspects of the leaves, which is the result1 of a periodic change, affecting either the posi- tion of the leaf as a whole, or that of the se- veral leaflets of which a compound leaf isj formed. The petioles, or stalks of the leavesj or leaflets, either bend upwards or down- wards ; so that the flattened surface of th< leaf is either elevated or depressed. This i: not a result of simple flaccidity ; for, as D< Candolle remarks *, the nocturnal position i; maintained with the same rigidity and con stancy as the diurnal; so that the “sleeping, leaf would be broken, more readily than i could be forced into the position which i proper to it during the day. Eleven differed modifications are enumerated by the distin guished botanist just cited, in the mariner ii] which the leaves incline themselves to th stalks on which they grow. Thus, of th entire leaves which exhibit this phenomenor some sleep face to face, others back to bad * Physiologic Yegetale, p. 855. SLEEP. others fold in at the sides so as to embrace the stem or to protect the flower which arises from their axil. It is rare to see a movement of the whole of a compound leaf, when its in- dividual portions fold together ; such a move- ment is seen, however, in the Mimosa. The variety of positions assumed in sleep by the subdivisions of compound leaves is very con- siderable, and need not be here enumerated : the phenomenon is best exhibited by the Le- guminosce and the Oxalidece. Of the causes of this phenomenon, little can be definitely stated. They are not to be looked for solely in the operation of exter- nal physical agents, such as light, heat, and moisture ; for it can be easily shown that the changes in question cannot be thus accounted for, without attributing to the plants by which it is exhibited a tendency to such periodical manifestations inherent in their own consti- tution. Thus, when sensitive plants are con- fined in a dark room, their leaflets periodically fold and open as usual ; the periods, however, being somewhat lengthened. On the other hand, when exposed to continued light, the periodical folding and unfolding still occurs, but the periods are shortened. And when the plants are exposed to strong lamplight by night, and excluded from all light by day, their periods of sleep become extremely ir- regular for a time, but in the end the plants generally close their leaves during the day and open them at night. No such modifica- tions can be induced, however, in the Oxalidece ; their periods of opening and closing their leaves being unaltered hy light, darkness, or by the disturbance of the natural sequence of the two. In the same manner it may be proved that these movements cannot be laid to the account of changes of temperature; for it appears from the experiments of De Candolle, that they continue to take place in plants exposed to various degrees of temperature, as well as in those left in air, provided that the heat or cold be not sufficient to injure the health of the plants. And by the same method of exclusion, they can be shown not to be dependent upon variations in the amount of circumambient moisture ; since they con- tinue equally well, cceteris paribus, when plants are kept in stoves the humidity of whose at- mosphere is uniform, and in some cases even when the plants are entirely immersed in water. We must conclude, then, that al- though the exact time of the occurrence of the phenomenon may be liable to modification irom the influence of external agents, its per- formance is essentially independent of them, aud must be referred to causes inherent in the plant itself. The periodical closing of flowers is a change which is obviously analogous to the sleep of leaves. Many flowers only expand themselves once, and speedily wither. Even in this case, however, there is often considerable regularity in the time of expansion, indicating periodi- city. But in the flowers which remain fresh for some days, some degree of alternation between closure and expansion may be gene- 679 rally discerned. There is no definite rela- tion, however, between the sleep of flowers and that of leaves ; for they may be united in the same individuals, or be exhibited sepa- rately in different species of the same genus. Among other curious examples which show the absence of connection between the two classes of phenomena, is one cited by De Candolle from Berthollet; the subject of it being an Acacia cultivated in the garden at Orotava, in which the leaves closed at sunset, but the flowers then expanded, their numerous stamens raising themselves up like tufts of feathers, so as to become conspicuous ; whilst in the morning, when the leaflets assumed their di- urnal position, the filaments relaxed so that the bunches of stamens gave to the flowers the appearance of floss-silk, and the flowers them- selves partly closed together. It has been ascertained by Meyen, that, by the action of artificial light and darkness, the usual hours for opening and closing may be changed in flowers as well as in leaves. Thus he found that after passing two days in a room from which external light was excluded, but which was lighted by four Argand lamps, the flowers of Ipomcea purpurea , which natu- rally open during the night, expanded in the morning ; whilst those of Oxalis tetrapliylla, at the end of the fourth day of artificial illumi- nation, opened in the evening, instead of at their usual morning hour. Periodicity of Sleep. — There can be little doubt that a tendency to occasional repose is inherent in the constitution of every animal possessed of a sensorial apparatus; and that this disposition is so arranged as to correspond in its periodical recurrence with the diurnal revolution of the earth. Al- though we are accustomed to think that “ night is the time for sleep,” and although, in our own case and in that of most other animals, darkness and silence favour repose, yet it must be borne in mind that there are many tribes of animals whose period of activity is the very same with that during which most others are wrapped in slumber. Thus, among lepidopterous insects, we find the activity of the greater part of the butter- flies to be diurnal, that of the sphinges to be crepuscular, and that of the moths to be nocturnal. So among the insectivorous birds, we find the diurnal swallow replaced during the night by the goatsucker (or night-jar) ; whilst the insectivorous bats are most active during twilight. Among the raptorial birds, again, we find the whole tribe of owls, with only one or two exceptions, to be either noc- turnal or crepuscular in their activity. And among carnivorous animals we meet with a similar diversity. As a general rule, the vegetable-feeders of all tribes are diurnal in their activity, taking their repose at night. The nocturnal predaceous animals take their repose during the day ; and those whose period of activity is the twilight, sleep partly by night and partly by day. Notwithstanding this variety as to the periods of sleep and activity, the complete xx 1 SLEEP. 680 cycle in every case is fulfilled in twenty-four hours ; and this uniformity in their recurrence would seem to indicate either an entire and invariable dependence on external agencies, or else a periodical tendency to sleep, inherent in the animal kingdom, and corresponding with the cycle of day and night. The ex- perience of the human species seems to be decisive in favour of the latter view. There is, among all tribes of mankind, a general uniformity in the periods of slumber and activity, which is scarcely inferior to that observable among tbe lower animals; yet we find reason to believe that this periodicity is a law of our own organic constitution, for it is quite certain that it cannot be seriously de- parted from without injury to the system, and that, even where light and warmth are continuous through the whole range of the twenty-four hours (as during the summer in arctic regions), the same periodical desire for sleep manifests itself, resistance to which is prejudicial to the health. As Dr. Whewell justly remarks# — “ No one can doubt that the inclination to food and sleep is periodical, or can maintain, with any plausibility, that the period may be lengthened or shortened with- out limit. We may be tolerably certain that a constantly-recurring period of forty-eight hours would be too long for one day of em- ployment and one period of sleep, with our present faculties ; and all whose bodies and minds are tolerably active will probably agree, that, independently of habit, a perpetual al- ternation of eight hours up and four in bed would employ the human powers less advan- tageously and agreeably than an alternation of sixteen and eight.” We may remark, however, that when the habit has been once acquired, the shortening of the cycle is probably not so injurious as its extension. We know by ex- perience that the habitual attempt to sustain an uninterrupted activity during more than sixteen or eighteen hours at a time, is either unsuccessful, or, if successful, is very wearing to the system. On the other hand, the ex- perience of seamen who kept “ watch and watch” during long voyages without any ob- vious injury to their health, indicates that if the due amount of sleep be obtained within every twenty-four hours, the division of the cycle is not attended with any prejudicial effect. On the whole, we may conclude with Dr. Whewell, that, “ when we have sub- tracted from the daily cycle of the employ- ments of men and animals, that which is to be set down to the account of habits acquired, and that which is occasioned by extraneous causes, there still remains a periodical cha- racter, and a period of a certain length, which coincides witn, or at any rate easily accom- modates itself to, the duration of the earth’s revolution. Causes of Sleep. — The most potent of all the causes of sleep, which is capable of acting by itself, when in sufficient intensity, in opposition to the most powerful influences tending to the continuance of wakefulness, is the condition * Bridgewater Treatise, p. 40. of the nervous system induced by its pro- tracted functional activity. Sleep may thus come on in the midst of the roar of cannon, and this not merely in persons accustomed to the noise, but in those who have never previously experienced it. Thus it is on record that during the heat of the battle of the Nile, some of the boys who were over-fatigued fell asleep on the deck. We have known a listener to an orchestral performance drop off in slumber during the noisiest part of the grand finale. Again, the continued demand for muscular activity is not incompatible with the access of sleep. During fatiguing marches, as in the retreat to Corunna, it has been repeatedly noticed that whole battalions of infantry have slumbered whilst in motion ; muleteers frequently sleep on their mules, coachmen on their boxes, and post-boys on their horses ; and factory children, before the shortening of the hours of work, were often known to fall asleep whilst attending to their machines. Bodily pain, again, yields before the imperative demand occasioned by the continued exhaustion of the powers of the sensorial centres. Of this the medical prac- titioner has frequent illustrations. It is well known, too, that the North American Indians, when at the stake of torture, will go to sleep on the least remission of agony, and will slumber until the fire is applied to awaken them. It is related that Damiens slept during his protracted tortures upon the rack ; and that this having been prevented by the con- stant renewal of fresh torments, he spoke of the want of sleep, a little before the termi- nation of his existence, as the most dreadful of all the sufferings he had endured. That the strongest voluntary determination to remain awake is forced to give way to the demand for sleep produced by the exhaustion of nervous power, must be within the ex- perience of every one. It does not appear to be of any consequence whether this exhaustion is produced by the active exercise of volition, emotion, reflection, or simple sensation. In all alike the sen- sorial centres must participate ; by all alike, therefore, must their nervous substance be subjected to that disintegration which cannot proceed beyond a certain point without either being repaired by sleep, or producing a state (l of exhaustion which becomes fatal. Never- theless, we find that the involuntary con- tinuance of mental activity is unfavourable to" access of sleep, so as to oppose the action of other predisposing influences; and such per- sistence will be found to be especially difficult to check in cases in which the feelings are concerned. The activity of the purely intel- lectual operations, which can be suspended at any moment, provided tbe feelings be not interested in their continuance, predisposes to sleep instead of preventing it. But the desire to work out a result, or to complete the survey of a subject, is an emotional state which in- duces restlessness, remaining active until it is gratified. So, again, anxiety or distress is a most frequent cause of wakefulness ; the ex- SLEEP. citementof the feelings keeping up vi forced state of mental activity, which no voluntary effort can subdue. The state of suspense is in most persons more difficult to bear with equanimity, and is more opposed to the access of sleep, by the continual perturbation which it induces, than the greatest joy or the direst calamity when certainty has been attained. Thus it is a common observation that criminals under sentence of death sleep badly so long as they entertain any hopes of a reprieve ; but as soon as they are satisfied that their sentence will be certainly carried into execution, they usually sleep more soundly, — anti this even on the very last night of their lives. That the continued excitement of the feelings, whilst producing an indisposition to sleep, really occasions as great a demand for it in the system as is produced by the most active ex- ercise of the intellectual [lowers, is evident from the very exhausting effects of its pro- traction ; which necessitate a long period of tranquillity for restoration to health. Among the most powerful of the predis- posing causes to sleep, is the absence of sensorial impressions : thus darkness and silence usually conduce to repose ; and the cessation of the sense of muscular effort, which takes place when we assume a position that is sustained without it, frequently acts as the complement of all other influences. There are cases, however, in which the continuance of an accustomed sound is necessary instead of positive silence, the cessation of the sound being a complete preventive of sleep. Thus it happens that persons living in the neigh- bourhood of the noisiest mills or forges cannot sleep elsewhere; and when, to induce repose in illness, the mill or the forge has been stopped, the cessation of the sound only occasions more obstinate wakefulness. Such instances, perhaps, fall within the next category of predisposing causes, — namely the monotonous repetition of sensorial impres- sions. Every one knows how efficacious a provocative of sleep is the droning voice of a heavy reader, especially when his subject is equally prosaic. The ripple of the calm ocean upon the shore, the murmur of a rivulet, the sound of a distant waterfall, the rustling of foliage, the hum of bees, and similar monotonous impressions upon the auditory sense, are usually found to induce sleep ; and Boerhaave relates, that being desirous of pro- curing sleep for one of his patients troubled with obstinate insomnia, he directed a brass pan to be so placed as to receive a succession of drops of water, the sound of which had the desired effect. A lulling influence, however, is not universally thus produced ; for we have known a case in which sleep was altogether kept away by the sound of dropping water, which seems to have occasioned a state of emotional excitement. Not only is the repe- tition of auditory impressions provocative of sleep ; uniform succession of gentle movements has a similar effect upon the sensorium through the sense of vision. The sleep thus induced, however, is usually characterised by 681 certain peculiarities which will be described hereafter. — The recurrence of impressions received through the sense of touch has the same effect. Thus Dr. Elliotson says*, — “ I know a lady who often remains awake in spite of every thing, till her husband very gently rubs her foot ; and by asserting to a patient my conviction that the secret of an advertising hypnologist whom I allowed to try his art upon the sleepless individual, and which he did for a time successfully, was to make him gently rub some part of his body till he slept, he confessed this to be the fact.” The rocking of the infant’s cradle, or the gentle swaying of the body backwards and forwards in the arms, are predisposing causes of sleep well known to nurses. In these and similar cases, the influence of the impressions would seem to be exerted in withdrawing the mind from the conscious- ness of its own operations, the loss of which, as we shall presently point out, is the tran- sition-step of the passage into complete un- consciousness. The reading of a dull book acts in the same mode. There is a monotony of sensorial impressions, the eyes wandering on from line to line and from page to page, without any mental interest in the sensations received; and if the voluntary effort of atten- tion be intermitted, the thoughts pass off along their own spontaneous train, whilst the sensorial centres are left free to the soporific influence of monotony. The foregoing are the chief causes of sleep, which operate directly through the sensorial organs themselves. YVe have now to consider those whose action is indirect, being exerted primarily on the organic functions. Of these the first in order of importance are those which produce increased pressure of blood within the vessels of the encephalon. Thus the assumption of the recumbent position operates in this method as a powerful predis- ponent to sleep, as well as by rendering all muscular effort unnecessary for the mainte- nance of the position of the body. To this cause again we are probably to attribute, in great part at least, the drowsiness which suc- ceeds a full meal, the pressure within the encephalic vessels being increased by the pres- sure of the distended stomach upon the ves- sels of the abdomen ; but the circulation of imperfectly assimilated matter in the blood may possibly concur in the production of the result. The influence of pressure is most characteristically seen in cases of gradual effusion of blood or of serum from the vessels of the brain : this at first occasions a state of sopor but little different from profound or- dinary sleep ; but with the increase of the effusion there is an increase in the depth of the slumber; the patient can no longer be aroused by sensorial impressions which were at first sufficient to re-excite consciousness, and at last complete coma comes on.j- A * Physiology, p. 609. f Dr. Marshall Hall has advanced the hypothesis, that ordinary sleep is the result of congestion of the brain produced by compression of “ certain veins,” 682 SLEEP. moderate degree of warmth favours sleep ; perhaps by increasing the energy of the heart’s contractions, at the same time that the walls of the vessels are more relaxed than usual, and thus yield to the impulse. A moderate degree of cold usually has the opposite effect, more especially when the cold is sufficient to produce uneasy sensa- tions. But cold of great severity produces drowsiness, sopor, and even complete coma ; apparently by producing a contracted state of the superficial vessels of the body, and thus occasioning an increase of sanguineous pres- sure on the encephalic centres. Again, the circulation of blood charged with narcotic substances through the brain, is one of the most powerful of all hypnotising agencies ; and this, again, may produce every gradation of effect, between simple sleep, from which the patient may be easily aroused, and the profoundest coma. One of the most com- mon instances of the operation of this cause, is the production of drowsiness by a deficiency of ventilation ; the carbonic acid which accu- mulates in the blood, when not freely carried off in the air, having the properties of a pow- erful narcotic. Phenomena of ordinary Sleep. — The state of perfect sleep is characterised by negative rather than by positive phenomena. As al- ready stated, it essentially consists in the complete suspension of the sensorial powers, and of all those movements in which the nervous system participates, except the simply reflex : with this is conjoined a partial or complete suspension of the functional activity of the cerebrum. According to the more or less potent operation of the soporific causes, will be the degree of insensibility to impres- sions upon the afferent nerves. No ordinary cause, as we have already shown, is so power- ful as previous fatigue. Of the profoundness of the sleep which may result from it, — in combination, perhaps, with two other agents, warmth, and an atmosphere somewhat charged with carbonic acid, — the following remark- able example may be cited from the “Journal of a Naturalist.” It may be proper to men- tion that, the correctness of the statement having been called 'in question, it was fully confirmed by Mr. Richard Smith, the late senior surgeon of the Bristol Infirmary, un- der whose care the sufferer had been. “ A travelling man, one winter’s evening, laid him- self down upon the platform of a lime-kiln, placing his feet, probably numbed with cold, upon the heap of stones, newly put on to burn through the night. Sleep overcame him in this situation ; the fire gradually rising and increasing, until it ignited the stones upon by “ a state of contraction of certain muscles of the neck.” (See his Observations in Medicine, second series, p. 27.) He does not, however, offer the least proof of this hypothesis, nor does he even name the muscles or veins to which he refers. We presume that the platysma myoides and the external jugular are meant. If so, why should not a slight com- pression of the vein by any other means have the effect of producing sleep at will ? which his feet were placed. Lulled by the warmth, the man slept on ; the fire increased until it burned one foot (which probably was extended over a vent-hole) and part of the leg above the ancle entirely off, consuming that part so effectually, that a cinder-like fragment was alone remaining, — and still the wretch slept on ! and in this state was found by the kiln-man in the morning. Insensible to any pain, and ignorant of his misfortune, he attempted to rise and pursue his journev, but missing his shoe requested to have it found ; and when he was raised, putting his burnt limb to the ground to support his body, the extremity of his tibia crumbled into frag- ments, having been calcined into lime. Siiil he expressed no sense of pain, and probably experienced none, from the gradual operation of the fire, and his own torpidity during the hours his foot was consuming. This poor drover survived his misfortunes in the hos- pital about a fortnight ; but the fire having extended to other parts of his body, recovery was hopeless.” It may be added that cases are recorded by medico-legal writers, in which defloration of a virgin, followed by concep- tion, lias been effected whilst she was in a state of ordinary sleep, rendered unusually profound by previous fatigue ; but such state- ments are obviously liable to considerable doubt, and scarcely appear entitled to cre- dence. Besides the suspension of the sensorial functions, however, there is usually a slight diminution in the activity of the functions of organic life. The heart’s contractions are less frequent, but the pulse is fuller. So likewise the respiratory movements are diminished in number ; but the inspirations are deeper. Less carbonic acid is produced than during a similar bodily inactivity in the waking state, j As might be expected from these differences, the amount of heat generated in the body is diminished, and there is much less power of j resisting the effects of cold. So remarkable ! is this abatement, that when the body is exposed to intense cold (as in the well-known j attempt of Sir Joseph Banks and Dr. Solander to explore Terra del Fuego), “ to sleep is to die.” There would seem, too, to be a dimi- nution in the power of resisting other mor- bific agencies. Thus all authorities agree that I sleeping in a malarious atmosphere is much more liable to engender the diseases produced by it, than spending the same length of time in the same place, but in the waking state. As a general rule, it would seem that the secreting processes go on with diminished activity during sleep ; but to this the cuta- neous transpiration is an exception, so that, in debilitated states of the system, a profuse sweating often occurs as soon as the patient falls asleep. From this diminished activity of the organic functions it happens that hun- ger is not renewed so speedily after sleep as when the same number of hours have been passed in watching ; a fact well known to those who are liable to suffer habitually or occasionally from the want of food. In this SLEEP. 683 respect-, then, even the ordinary sleep of the warm-blooded animal may be regarded as an incipient hybernation. Some writers have spoken of the organic functions as performed with increased activity during sleep ; a doc- trine so inconsistent with obvious facts, that it could never have been sustained except on the basis of a preconceived idea with regard to the antagonism between the relative ac- tivity of the functions of organic and animal life, which idea is in itself fallacious. The actual renovation of the nervous and mus- cular tissues by the nutritive processes, pro- bably takes place with peculiar energy during the functional inactivity of those parts ; but the preparation of the nutritive materials, which is the office of the digestive and as- similative apparatus, seems to go on more slowly during sleep ; and it is quite certain that less oxygen is then taken into the sys- tem, and less carbonic acid generated and set free. The access of sleep is sometimes quite sudden ; the individual passing at once from a state of mental activity to one of complete torpor. More generally, however, it is gradual; and is marked by phenomena which are par- ticularly worthy of attention. “While the mind remains poised, as it were, between sleep and the opposite condition,” says Dr. Macnish*, “it is pervaded by a strange confusion, which almost amounts to wild delirium ; the ideas dissolve their connection from it, one by one ; those which remain longest behind are faint, visionary, and indistinct; and its own essence becomes so vague and diluted, that it melts away in the nothingness of slumber ; as the morning vapours are blended with the sur- rounding air by the solar heat.” In this passage there is an attempt made to depict the result of the loss of that power of voluntary control over the current of thought, the possession of which is the especial characteristic of the human mind in its state of normal activity. It is the complete suspension of this power, as we shall presently see, which, taken in connection with the entire want of sensibility to external objects, constitutes the state of dreaming ; and the same suspension, occurring before the mind is altogether withdrawn from connection with the external world, constitutes that curious intermediate state betwixt sleeping and waking, which may readily pass into either condition. Thus, if the torpor of the sen- sorial centres be allowed to increase, sleep is produced ; but if it be dissipated by some sen- sory impression of unusual strength, wakeful- ness is brought back again, a dreamy impression remaining, both of what had been passing in the mind itself, and of that which had been taking place around. Now, it appears to be by suspending the mind’s attention to its own proceedings, and by drawing off the attention of the sensorium from all other impressions upon the organs of sense, that the monoto- nous sensations already referred to favour the access of sleep. And it may be further affirmed that all the successful plans for vo- * Philosophy of Sleep, p. 21. luntarily producing sleep have some such modus operandi; their success being dependent upon the intentional fixation of the thoughts upon some one class of sensory impressions (as in the method of Mr. Gardner), or upon some very simple and uniform mental process (such as counting, repeating a French or Greek verb, &c.); and when the attention has been once thus fixed, the monotony of the impression serves to retain it there, so that it abandons, as it were, all control over its operations, and allows itself to be gradually wrapped in repose under the influence of that continued recurrence of similar impressions, which seems even more potent as a soporific than the suspension of all sensational stimuli. The gradual loss of consciousness and of voluntary control over the muscular system during the invasion of sleep is thus described by Dr. Macnish : — “Previous to the acces- sion of sleep, a feeling of universal lassitude prevails ; this sensation heralds in the phe- nomena of slumber, and exhibits itself in yawning, heaviness of the eyes, indifference to surrounding objects, and all the characteristics of fatigue. If the person be seated, his head nods and droops, and, in all cases, the muscles become relaxed, and the limbs thrown into that state most favourable for complete mus- cular inaction. The lying position is, con- sequently, the best adapted for sleep, and the one which is intuitively adopted for the pur- pose. The organs of the senses do not re- lapse into simultaneous repose, but suspend their respective functions gradually and suc- cessively ; sight, taste, smell, hearing, and touch, parting with sensation in the order in which they here stand, and gliding insensibly away. In the same manner the muscles do not become simultaneously relaxed ; those of the limbs giving way first, then those of the neck, and lastly the muscles of the spine. Nor do the external senses, on awaking, re- cover all at once their usual vigour ; we, for some seconds, neither hear, nor see, nor smell, nor taste, nor touch, with our usual acuteness. Ordinary sights dazzle our eyes; ordinary sounds confuse our ears ; ordinary odours, tastes, and sensations, our nose, our tongue, and our touch : they awake successively, one after another, and not in the same instant.” * The power of being aroused by impressions made upon the organs of sense, is, as already remarked, one of the chief distinctions be- tween sleep and stupor. The strength of the impression requisite to produce this effect depends upon two circumstances, which re- quire separate consideration : first, the pro- foundness of the slumber; and, second, the relation of the impression to the habitual condition of the mind. It is a familiar fact that most persons are much more easily aroused towards the morning, when the slum- bers are lighter, than they are during the early part of the night, when the sleep is more profound. In fact, the spontaneous awaken- ing which takes place when our repose has been sufficient for the restoration of mental Op. cit. p. 22. G84 SLEEP. vigour, may generally be traced to some sen- sory impression of a trivial nature, such as the striking of a clock, which would have pro- duced no effect at a previous time. Some persons, however, always sleep so heavily, that they require a strong impression to arouse them, even when they have had an ample allowance of repose. It is through the hearing and the touch that the awakening im- pressions are ordinarily conveyed ; but either of the other senses may serve as their channel. Thus, although the closure of the eyelids destroys the acuteness of the perception of light, the eyelids are sufficiently transparent to allow of an impression being made by a light of moderate intensity ; so that those who sleep in a room whose window has an eastern aspect, and is not furnished with sufficient means of excluding the sun’s rays, are liable to be aroused by their ingress some time before the natural amount of repose has been taken. So, again, the sleeper may be awakened by unusual odours ; thus the inmates of a burning house are sometimes first aroused by the smell of fire. The introduction of sub- stances possessing a strong taste into the mouth, will also usually put an end to the state of slumber ; but when the slumber is very profound, such substances may be re- ceived, and even swallowed, without the sleeper being thereby awakened. The variety of modes in which the oper- ation of sensory impressions on the sleeper is modified by the previous habitual state of mind, is one of the most remarkable points of the whole subject. The general rule is, that habitual impressions of any kind have much less effect in arousing the slumberer, than those of a new or unaccustomed character. An amusing instance of this kind has been related to the author, which, even if not literally true, serves extremely well as an illustration of what is unquestionably the or- dinary fact. A gentleman who had taken his passage on board a ship of war, was aroused on the first morning by the report of the morning gun, which chanced to be fired just above his berth ; the shock was so violent, as to cause him to jump out of bed. On the second morning he was again awoke, but this time he merely started and sat up in bed ; on the third morning the report had simply the effect of causing him to open his eyes for a moment, and turn in his bed : on the fourth morning it ceased to affect him at all, and his slumbers continued to be undisturbed by the report as long as he remained on board. It often happens that sleep is terminated by the cessation of an accustomed sound, especially if this be one whose monotony or continuous repetition had been the original inducement to repose. Thus, a person who has been read or preached to sleep, will awake, if his slum- ber be not very profound, on the cessation of the voice ; and a naval officer, sleeping be- neath the measured tread of the watch on deck, will awake if that tread be suspended. In this latter case, the influence of the simple cessation of the impression will be augmented by the circumstance next to be alluded to, which has received too little attention from writers on this subject, but which is of pe- culiar interest both in a physiological and psychological point of view, and is practi- cally familiar to almost every one. This is, that the influence of sensory impressions is greatly modified by our habitual state of mind in regard to them. Thus, if we are accustomed to attend to these impressions, and our perception of them is thus increased in acuteness, we are much more easily aroused by them than by others which are in them- selves much stronger, but of which we have been accustomed to entertain an utter dis- regard. Thus, most sleepers are aroused bv the sound of their own names uttered in a low tone, when it requires a much louder sound of a different description to produce any manifestation of consciousness. The same thing is seen in comatose states ; a patient being often capable of being momentarily aroused by shouting his name into his ear, when no other sound produces the least effect. The following circumstance, commu- nicated to the author by a naval officer of high rank, is a most apposite illustration of this principle. When a young man, he was serving as signal-lieutenant under Lord Hood, at the time when the French fleet was con- fined in Toulon harbour ; and being desirous of obtaining the favourable notice of his com- mander, he devoted himself to his duty — ■ that of watching for signals made by the look- out frigates — with the greatest energy and perseverance, often remaining on deck nine- teen hours out of the twenty-four, with his attention constantly directed towards this one object. During the few hours which he spent in repose, his sleep was so profound, that no noise of an ordinary kind, however loud, would awake him ; and it used to be a favourite amusement with his comrades, to try various experiments devised to test the soundness of his sleep. But if the word “ signal ” was even whispered in his ear, he was instantly aroused, and fit for immediafe duty.. It is not requisite, however, that the sound should be one habitually attended to during the hours of watchfulness ; for it is sufficient if it be one on which the attention has been fixed as that at which the slumberer is tc arouse himself. Thus the medical man, even in his first profound sleep after a fatiguing day’s work, is aroused by the first stroke of the clapper of his night-bell ; and to those who are accustomed to rise every morning at the sound of an alarum-clock, the fre- quency and regularity of the occurrence do not diminish, but rather increase, the readi- ness with which it produces its effect, pro- vided that the warning be promptly obeyed. On this usually depends the efficiency of the awakening sound ; if it be disregarded as a thing to which there is no occasion to give heed, it very soon ceases to produce any effect, the entire peal not being sufficient to awake the sleeper; whilst, on the other SLEEP. 685 hand, the first stroke is enough to break the repose of him who is impressed with the effectual desire of profiting by the warning. And thus it may happen that, of two persons in the same room, either shall be at once aroused by a sound which produces no disturbance in the slumbers of the other. — The influence of habitual attention, is shown as much in the effect produced by the cessation, as in that of the occurrence, of sensory impressions. Thus in the case of the naval officer aroused by the suspension of the measured tread of the watch over his head, the knowledge possessed during the waking state that this suspension is either an act of negligence which requires notice, or indicates some unusual occurrence, doubtless augments the effect which the dis- continuance of the sound would of itself produce. Putting aside the awakening influence of external impressions, the period of natural termination of the slumber is greatly influenced by habit. Thus, many persons who are ac- customed to rise at a particular hour, wake regularly at that hour, whether they have gone to rest early or late ; so that the act of spontaneously awakening is no proof that the desirable amount of repose has been obtained. But what is more remarkable is, that many individuals have the power of determining, at the time of going to rest, the hour at which they shall rise, so as to awake from a pro- found sleep at the precise time fixed upon. In others, however, the desire to rise at a particular hour only induces a state of rest- lessness throughout the night, destroying the soundness of the slumbers : the individual awakes many times in the night, with the belief that the hour is past, and very possibly oversleeps it after all, the system being worn out by the need of repose. The Amount of sleep required by man is affected by many conditions, especially age, temperament, habit, and previous exhaustion ; so that no general rule can be laid down upon the subject. The condition of the foetus in utero may be regarded as one of continual slumber ; the energy of the organic functions being entirely directed to the building-up of the organism, whilst the apparatus of animal life is completely secluded from all the stimuli which could arouse it into activity. On its first entrance into the world, the infant con- tinues to pass the greater part of its time in slumber; and this is particularly to be noticed in cases of premature birth, — the seven months’ child seeming to awake only for the purpose of receiving food, and giving but little heed to any external objects when its internal cravings are satisfied ; and even the eight months’ infant being considerably less alive to sensory impressions, than one born at the full time. During the whole period of infancy and child- hood, it is necessary for the development of the body that the constructive operations should be more energetic than the destructive; and, accordingly, we find that the period of sleep, during which the former take place without hindrance, is longer in proportion to the waking state, during which the latter aro in play, than it is when full growth has been obtained.* As age advances, the necessity for very rapid nutrition gradually diminishes, in conse- quence of the progressive approach to com- plete development ; and when the adult period has been attained, it is not requisite that the constructive processes should do more than balance the destructive. The amount of sleep requisite for this purpose, therefore, gradually diminishes, until it is reduced to (at most) one-third of the cycle of twenty-four hours. It is to be noticed that the sleep of children and young persons is not only longer than that of adults, but is also more profound. On the other hand, as age advances, and the bodily and mental activity of the waking state decreases, a smaller amount of sleep suffices ; or, if the slumber be protracted, it is usually less deep and refreshing. It may be noticed, however, that very old persons usually pass a large proportion of their time in sleep, or rather in dozing; as if, in consequence of the want of energy of their nutritive operations, a very long period of repose is necessary to repair the waste which takes place during their short period of activity. It is stated f that “ the celebrated De Moivre slept twenty hours out of the twenty-four ; and Thomas Parr latterly slept away by far the greater part of his existence.” The repose of the aged is most apt to take place immediately after taking food ; while they solicit it in vain at that period at which, during the former years of their lives, they had been ac- customed to enjoy it. The amount of sleep, again, is much af- fected by temperament. It will generally be found that a plethoric habit of body, sustained by full diet, predisposes to sleep, provided the digestive powers be in a vigorous con- dition. Such persons frequently pass nine or ten hours in slumber, and maintain that they cannot be adequately refreshed by less. On the other hand, thin wiry people, in whom the “ nervous” temperament predominates, usually take comparatively little sleep, not- withstanding the greater activity of their ner- vous system when they are awake ; but their slumber, while it lasts, is generally very deep. Persons of “ lymphatic” temperament, heavy * It is to be remembered, when we compare the condition of the nutritive operations during the period of growth, and after the complete development of the organism, that it is not in the mere amount of accretion that the difference consists. This would be the case if the new matter were merely added to the old, as in the formation of a new layer of wood in an exogenous stem. The growth of the animal fabric requires a continual new development of every part of it, involving a constant change in its mate- rials ; and thus we see that the amount of food required by children, and the quantity of urea, and other products of the disintegration of the tissues set free in their excretions, bear a much larger proportion to those of the adult, than would be inferred from the relative bulk of the body at the two periods, and from its rate of increase during the former. f Macnisli, op. cit. p. 37. 686 SLEEP. passionless people, who may be said to live very slowly, are usually great sleepers ; but this rather because, through the dullness of their perceptions, they are less easily kept awake by sensorial or mental excitement, than because they really require a prolonged cessa- tion of activity. As they are half asleep during the waking state, so would it appear that the constructive operations must be far from active while they are asleep, — so little do they seem restored by the repose. The amount of sleep, c ceteris paribus , re- quired by individuals, is very greatly influenced by habit ; and, contrary to what we might anticipate, we find that the briefest sleepers have usually been men of the greatest mental activity. Thus Frederick the Great and John Hunter are said to have only required five hours’ sleep out of the twenty-four. General Elliot, celebrated for his defence of Gibraltar, is re- corded not to have slept more than four hours out of the twenty-four.* Sir Gilbert Blane states f that General Pichegru informed him that, “ in the course of his active campaigns, he had for a whole year not more than one hour of sleep, on an average, in twenty-four hours.” We suspect that if he had said “ one hour of sleep at a time,” he would have been nearer the truth. This we believe to have been the case with regard to the Duke of Wellington during the Peninsular campaigns. Dr. Elliotson saysj, “ I heard Baxter, the coach maker, declare that he never took more than three hours’ sleep during the most active period of his life.” We doubt if it would be possible for any one to sustain a life of vigorous exertion with a smaller allow- ance than this. The influence of habit is further shown in producing an aptitude for repose, or a readiness to wake, at particular periods. Thus, if a man is accustomed to go to rest at ten o’clock, and to rise at six, he will pro- bably awake at six, even if he have not fallen asleep until twelve. And in like manner, if the morning sleep have been unusually protracted, the desire for sleep will probably return at the accustomed hour in the evening. The influence of habit is further exerted in producing an aptitude for sleep whenever the opportunity is afforded. Thus, the celebrated pedestrian Capt. Barclay, when accomplishing his extraordinary featof walking 1000 miles in as many successive hours, obtained at last such a mastery over himself that he fell asleep the instant he lay down. And the sleep of soldiers, sailors, and others, who may be pre- vented from obtaining regular periods of re- pose, but are obliged to take their rest at short intervals, may be almost said to come at command ; nothing more being necessary to induce it than the placing the body in an easy position, and the closure of the eyes. On the other hand, habit favors the protrac- tion of sleep. This was the case with Quin, the celebrated actor, who could slumber for * Mannish, op. cit. p. 34. t Medical Logic, p. 83. j Physiology, p. 601. twenty-four hours successively; and with Dr. Reid, the metaphysician, who could take as much food, and afterwards as much sleep, as were sufficient for two days. It is needless to dwell upon the obvious fact, that, other things being equal, the amount of sleep required by man is proportional to the amount of mental exertion put forth during the waking hours ; since this is an obvious result of what has been laid down as the cause of the demand for sleep. It may be remarked, however, that we must not measure the amount of sleep by its duration alone ; I since its intensity is a matter of equal import- ance. The light slumber which is disturbed by the slightest sounds, cannot be as reno- vating as the profound sopor of those whom no ordinary noise will awake. There are certain states of the nervous system in which there is an entire absence of steep ; and this may continue for many days, or even weeks or months. Insomnia is, for instance, one of the characteristics of acute mania, and may also exist in various forms of monomania. It is usually, also, one of the symptoms of incipient meningeal inflammation. And it may constitute a specific disease in itself. In all these cases, however, the pre- ponderance of the destructive processes over the constructive manifests itself, sooner or I later, in the exhaustion of the mental and bodily powers. Thus mania, when prolonged or frequently occurring, subsides into de- mentia. When meningitis (or rather inflam- mation of the surface of the hemispheric gan- glia) is fully developed, a rapid disintegration of nervous matter takes place, as indicated by the large amount of alkaline phosphates in the urine.* The same would probably be detected in cases of idiopathic insomnia; which state, if it continue for any length of time, is sure to be followed by a great sense of wretchedness and prostration, frequently ac- companied by continual restlessness. Such effects, too, in a less aggravated degree, result from habitual deficiency of sleep; whether this results from emotional excitement, whini keeps repose at bay, or from a voluntary de- termination to keep the intellect in activity. This is a very common occurrence among industrious students, who, with a laudable desire for distinction, allow themselves less than the needed quantum of repose. Head- ache, tension, heat, throbbing, and various other unpleasant sensations in the head, give warning that the brain is being overtasked; and if this warning be not taken, sleep, which it was at first difficult to resist, becomes even more difficult to obtain ; a state of general restlessness and feverish excitement are in- duced ; and if, in spite of this, the effort be continued, serious consequences, in the form of cerebral inflammation, apoplexy, paralysis, fever, insanity, or loss of mental power, more or less complete, are nearly certain to be induced. Some individuals can sustain such an effort much longer than others, but it is a great mistake to suppose that they are not * See Dr. Bence Jones in Phil. Trans. 1846. SLEEP. 687 equally injured by it ; in fact, being possessed with the belief that they are not suffering from the-exertion, they frequently protract it until a sudden and complete prostration gives a fearful demonstration of the cumulative effects of the injurious course in which they have been persevering. Those, consequently, who are earlier forced to give way, are fre- quently capable of accomplishing more in the end. In regard to the degree of protraction of sleep which is consistent with a healthy state of the system in other respects, it is difficult to speak with certainty. Of the numerous well-authenticated instances on record*, in which sleep has been continuously prolonged for many days or even weeks, it is enough here to state that they cannot be regarded as examples of natural sleep ; the state of such persons being more closely allied to hysteric coma. An unusual tendency to proper sleep generally indicates a congested state of the brain, tending to apoplexy ; and it has been stated that apoplexy has been actually induced by the experimental attempts to ascertain how large a proportion of the diurnal cycle might be spent in sleep. This effect may be readily explained, if we regard it as a general law of the capillary circulation, that its rate is increased by functional activity, and diminished by inactivity ; for whilst congestion of the brain arising from other causes will tend to produce sleep, through the augmented pres- sure it occasions, mental inactivity, if en- couraged and persisted in, will itself tend to produce congestion. Thus, on either side, inattention to the dictates of Nature in respect to the amount of sleep required for the renovation of the system, becomes a source of disease, and should therefore be carefully avoided. DREAMING. We have hitherto spoken of sleep in its most complete or profound form, — that is, the state of complete unconsciousness. But with the absence of consciousness of external things, there may be a state of mental activity, of which we are more or less distinctly conscious at the time, and of which our subsequent remem- brance in the waking state also varies in com- pleteness: theimpression being sometimes vivid, definite, and enduring; sometimes shadowy and evanescent ; sometimes not amounting to more than the feeling that we have dreamed ; and sometimes not even this being preserved, not- withstanding that there may be positive as- surance that the sleep has been thus disturbed. This state, known as dreaming, is one of the highest interest to the psychologist; but the limits imposed upon us forbid our doing more than enumerate its leading phenomena. The chief feature of the state of dreaming appears to be, that there is an entire absence of voluntary control over the current of thought ; so that the principle of suggestion — one thought * Such, for example, as that of Samuel Chilton (Phil. Trans., 1694), and that of Mary Lyall (Trans, of Roy. Soc. of Edinb., 1818). callingup another, accordingto the laws of asso- ciation— has unlimited operation. Sometimes the train of thought thus carried on is remark- ably consistent. We witness scenes that have occurred during our waking hours, and seem to hear, see, move, talk, and perform all the actions of life. We may experience every kind of mental emotion, and may even compare, reason, judge, and w ill, during our sleep ; and our reasoning processes have frequently a re- markable clearness and completeness, — the data on which they are founded being sup- posed to be accurate. This consistency is usu- ally the greatest, when the mind simply takes up a train of thought on which it had been engaged during the waking hours, not long previously ; and it may even happen that, in consequence of the freedom from distraction occasioned by the suspension of ordinary sen- sations, the intellectual operations may be carried on during sleep with uncommon vigour and success. Thus, to name only two instances, Condorcet saw, in his dreams, the final steps of a difficult calculation, which had puzzled him during the day ; and Condillac states that, when engaged with his “ Corn's d’Etude,” he frequently developed and finished a subject in his dreams, which he had broken off before retiring to rest. The imagination, equally with the reasoning processes, sometimes moves in a consistent course. Thus, Dr. Good relates the case of a friend who composed a little ode of about six stanzas, and set the same to agreeable music, in his sleep, the impression remaining so vividly that he was able to write down both the words and music on awaking in the morning ; and Coleridge relates of himself that his fragment, entitled “ Kubla Khan,” was composed during sleep, w'hich had come upon him whilst reading the passage in “ Purchas’s Pilgrimage ” on which the poetical description is founded, and was written down immediately on awaking. The images, he says, “ rose up before him as things, witha parallel production of the correspondent expressions, without any sensation or con- sciousness of effort.” It would seem ne- cessary, in most cases of this kind, that the results should be committed to paper imme- diately on waking, before the train of thought, continued from the dream, has been disturbed by any other. Thus, Coleridge tells us that, after having written for some little time, he was interrupted by a person on business, who continued with him above an hour ; and on the departure of his visitor, he found, to his surprise and mortification, that “though he still retained some vague and dim recollection of the general purport of the vision, yet, with the exception of some eight or ten scattered lines and images, all the rest had passed away like the images on the surface of a stream into which a stone had been cast; but, alas ! without the after-restoration of the latter.” In other cases, a strong general impression of what has passed through the mind in sleep may' remain on waking, without power of recalling the par- ticulars. This was the case in the well-known instance of the musician Tartini, to whom the 688 SLEEP. arch-fiend appeared in his sleep, and was challenged by him to a trial of skill : the dreamer lay entranced by the transcendent performance of his visitor, which surpassed anything he had ever heard or conceived ; on awaking, however, he could not reproduce the succession of notes, although he imme- diately seized his violin, and endeavoured to do so ; but, under the strong general impres- sion of what he had heard, he produced a new composition, which retains the name of the “ Devil’s Sonata.” But, although dreams may possess a re- markable coherence, whether as regards pro- cessses of reasoning, or the new combinations of the imagination, the general fact is, that such coherence is altogether wanting, and that there is a complete incongruousness in the thoughts and images which pass through our minds. All probabilities, and even possibilities of “ time, place, and circumstance ’’are violated; the dead pass before us as if alive and well ; even the sages of antiquity hold personal con- verse with us ; our friends at the antipodes are brought upon the scene, or we ourselves are conveyed thither, without the least per- ception of distance ; and the strangest combi- nations of reality and fancy are presented, either as objects passing before our con- sciousness, or as affecting our own condition. But of this incongruity we are seldom in the least aware. We are not capable of testing the probability or possibility of the phenomena by our ordinary experience. And, as a conse- quenceof this, nothing surprises us in dreams ; the feeling of surprise being the result, and indeed the measure, of our perception of the unlikelihood of a phenomenon. Not only is there usually a want of congruity in the in- tellectual processes, but a great disturbance in the ordinary play of the emotions. “Thus, in our dreams we may walk on the brink of a precipice, or see ourselves doomed to imme- diate destruction by the weapon of a foe or the fury of a tempestuous sea, and yet feel not the slightest emotion of fear ; though, during the perfect activity of the brain, we may be naturally disposed to the strong manifestation of this feeling. Again, we may see the most extraordinary object or event without surprise, perform the most ruthless crime without com- punction, and see what in our waking hours v\ould cause us unmitigated grief, without the smallest feeling of sorrow.” * This is, how- ever, by no means uniformly the case. In fact, our emotions in the dreaming state are often highly wrought; and it frequently seems that the excitement of some particular emotion gives the direction to the whole train of thought, and causes it to possess an unusual coherence and probability. This is most remarkable, perhaps, when the emotion in question has greatly occupied the mind in the previous waking hours. Thus, a female, whose husband is at sea, and for whose safety she naturally feels anxious, especially in stormy weather, is very apt to dream of shipwreck and all its at- * Prof. Wheatstone, quoted in Elliotson’s Phy- siology, p. 621. tendant circumstances ; or, on the other hand, a man in love dreams of his mistress, of married life, and of its various enjoyments. Even here, however, the congruity is frequently in- terrupted by the intervention of some strange occurrence; the oddity of which may be per- ceived by the dreamer as being discordant, not with the intellectual but with the emotional state. In simple dreaming, as there is a loss of voluntary control over the current of thought, so is there an absence of control over the muscular system. Movements expressive of emotions, however, may still take place, and may afford to the by-stander an indication of what is passing in the mind of the dreamer. The indications of fear, horror, or disgust, or of hope, rapture, or desire, — laughter or weeping, smiles or frowns, — may all display themselves, when there is an absolute cessation of all vo- luntary movements. This is remarkably the case in attacks ol incubus, or nightmare ; in which the dreamer is oppressed by intolerable distress, from which he makes vain attempts to free himself. His distress may be expressed by moans, or by the agitation of his coun- tenance ; but none of his fancied efforts are indicated by any respondent movements. This condition may subside into a state of tranquil slumber, or the agitation may increase to such a pitch as to awake the sufferer ; and as the first act ol the waking state is usually to cry out or kick violently, it has been supposed that the return of volition has been the cause, instead j ot being the effect, of the cessation of the op- pressive dream. There are cases, however, in which the dreamer executes movements in consonance with ideas passing through his mind, — such as would, in the waking state, be termed voluntary ; but these must be con- sidered as belonging rather to the category of somnambulism than to that of simple dreaming. The direction of the current of thought in dreaming is often given by impressions on the organs of sense, which influence the mental operations, by calling up associated ideas, without being recognized and perceived as i distinct sensations. Thus, Dr. James Gre- gory, having applied a hot bottle to his feet on going to bed, dreamt that he was walking up Etna and finding the ground intolerably hot. On another occasion, he dreamt of spending a winter at Hudson’s Ba}', and of suffering much distress from the intense frost; this evidently the consequence of his having thrown oft' the bed-clothes in his sleep, and of his having been reading, a few days before, a very particular account of the state of the colonies in that country during winter. Dr. lleid, having a badly-dressed blister on bis head, dreamt that he was being scalped by Indians ; and a man in a damp bed, that he was being dragged through a stream. A gouty man, when beginning to feel his pain in his sleep, may dream he is on the rack before inquisitors. The sound of music may excite delightful dreams. M. Girou de Buzarein- gues* made some curious experiments on * Journal de Pliysiologie, tom. viii. SLEEP. 689 this point, and directed at pleasure the cha- racter of his dreams. In his first experiment, having allowed the back of his head to be uncovered during sleep, he thought he was at a religious ceremony in the open air ; the custom of tlie country in which he lived being to keep the head covered excepting on some rare occurrences, among which was the per- formance of religious ceremonies. On waking he felt cold at the back of the neck, as he frequently had when present at the real cere- monies. He repeated the experiment in two days, with the same result. In a third ex- periment, he left his knees uncovered, and dreamt that he was travelling at night in the diligence; and all travellers know, he observes, that it is chiefly at the knees that they feel cold when travelling by that conveyance at night. The very remarkable degree in which this influence of external impressions is ex- erted, when sleep is being induced by the agency of certain narcotics, will be presently noticed. By the use of the term “ external ” is here meant that which is external to the mind itself. The dream may originate in im- pressions derived from any part of the bodily frame. Thus we find that indigestion is a very common cause of nightmare, and that an irritable state of the genital apparatus provokes lascivious dreams. When the ex- ternal impressions are recognized as sensa- tions, and the dreamer’s current of thought completely follows their guidance, so that even the meaning of spoken language is ap- preciated, the condition approximates to that of Somnambulism. One of the most remarkable of all the pecu- liarities of the state of dreaming, is the rapidity with which trains of thought pass through the mind ; a dream in which a long series of events has seemed to occur, and a multitude of images has been successively raised up, being often certainly known to have occupied but a few minutes or even seconds. This is best seen in those cases in which the dream has obviously originated in some sensory impres- sion, which has also had the effect of arousing the sleeper. A very interesting example of this, in which a similar dream was produced in two individuals, husband and wife, from the same cause, came within the knowledge of the late Dr. James Gregory. It happened when the public mind was much excited in regard to the alarm of French invasion, and the gentleman who was the subject of it was himself a zealous member of the Edinburgh volunteer corps. Whilst asleep, between two and three o’clock in the morning, he dreamt of hearing the signal gun: he was immediately at the Castle, witnessed the proceedings for displaying the signals to alarm the country', and saw and heard a great bustle over the town, from troops and artillery assembling, especially in Princes Street. At this time he was roused by his wife, who awoke in a fright, in consequence of a similar dream, connected with much noise and the landing of the enemy, and concluding with the death of a particular friend of her husband’s, who had VOL. tv. served with him as a volunteer. The origin of this remarkable occurrence was ascer- tained, in the morning, to be the noise pro- duced in the room above by the fall of a pair of tongs. How long the dream had continued in this instance is uncertain ; evidently not for a period in the least comparable to that required for the actual occurrence of the events that had passed through the mind of each ; and it is probable, from many similar cases, that the lady was awoke by the noise rather than by the fright. Thus a gentleman dreamt that he had enlisted as a soldier, joined his regiment, deserted, was apprehended, carried back, tried, condemned to be shot, and at last led out for execution. After all the usual preparations, a gun was fired ; he awoke with the report, and found that a noise in an adjoining room had both produced the dream and awoke him. The same feeling of duration, arising out of the number of images passing in succession through the mind, is often experienced when we are well assured that the whole duration of our sleep has not exceeded a few moments. We have known a clergyman fall asleep in his pulpit during the singing of the psalm before sermon, and awake with the conviction that be must have slept for at least an hour, and that the congrega- tion must have been waiting for him ; but on referring to his psalm-book, he has been con- soled by finding that his slumber has lasted no longer than during the singing of a single line. There would not seem, in fact, to be any limit to the amount of thought which may thus pass through the mind of the dreamer, in an interval so brief as to be scarcely capable of measurement ; and this view is confirmed by the circumstance, now well attested, that it is a common occurrence in drowning for the whole previous life of the individual to be presented instantaneously to his view ; with its every important incident vividly impressed on his consciousness, just as if all were combined in a picture, every part of which could be taken in at a glance. This, again, is connected with the fact that the operation of the associative principle may re- produce in dreams the remembrance of facts long since forgotten in the waking state. Such, however, is by no means peculiar to the state of dreaming ; for in the waking state we often retrace involuntarily and unexpectedly some- thing which we have in vain attempted to recall at will, and which might be said to have passed from our mental grasp. From the foregoing and other similar facts it has been argued, that all our dreams really take place in the act of falling asleep or of awaking ; so that even when we fancy that ■we have been dreaming all night, our uncon- sciousness has been really complete, except at these momentary intervals. That this doctrine cannot be altogether true is obvious from the fact, that we can frequently detect the character of a dream, and even in some degree trace its progress, by the expression of the sleeper’s countenance ; so that dreams certainly may occupy time, and occur during Y Y 690 SLEEP. ordinary sleep. On the other hand, it may be freely admitted that the apparent duration of our dreams does not afford the least measure of the time they have really occupied; and that it is probable that even when our sleep has seemed most disturbed by them, we have really passed a larger portion of the night in a state of complete unconsciousness than the mere impression left by our dreams would allow us to believe. But it has been questioned by some, on the other hand, whether there is ever such a state as that of complete unconscious- ness. It is affirmed that the mind can never be entirely inactive ; and that every body, in fact, does dream throughout the period of sleep, although the dreams may not be re- membered in the waking state. This state- ment is rather based upon the hypothesis with which it commences, than upon any positive facts ; and as it requires us to give up the simple teachings of ordinary experience, for the reception of a mere metaphysical dogma, the physiologist need not concern himself with the discussion. On the whole, it maybe said that dreaming indicates that sleep is imperfect ; and this view harmonises with the fact that between dreaming and the waking state there are various connecting gradations. Thus, reverie or day-dreaming differs from the dreaming of the sleeper, not so much in the condition of the mind and its instrument the cerebrum, as in that of the sensorium, which is not so com- pletely withdrawn in the former case, as it is in the latter, from the consciousness of external impressions. In sleep, on the other hand, the dreamer may have a consciousness of the un- reality of the images that arise in his mind, and may even make a voluntary and successful effort to prolong them if agreeable, or to dis- sipate them if unpleasing ; thus evincing the presence of that power of control over the current of thought, the want of which is one of the best characteristics of ordinary dreaming, as it is also of insanity, and indicating, there- fore, an unusual approximation to the vigilant condition. The action of narcotics on the nervous system presents many curious illustrations of the foregoing statements regarding the nature and phenomena of dreaming. There are some which have the power of inducing every con- dition intermediate between an unusual activity of the thoughts and a state of complete stupor, according to the dose taken. This is the case to a certain degree with opium; but still more decidedly with the extract of Cannabis Indica, a preparation of whch, known under the names of Hachiseh and Dawamesc, is much used in the East for the production of a species of agreeable intoxication. The first effect of a dose of this substance is usually to produce a moderate exhilaration of the feelings and an unusual activity of the intel- lectual powers ; but this activity gradually frees itself from voluntary control. The in- dividual feels himself incapable of fixing his attention upon any subject ; his thoughts being continually drawn offby a succession of ideas which force themselves (as it were) into his mind, without his being able in the least to trace their origin. These speedily occupy his attention, and present themselves in strange combinations, so as to produce the most fantastic and impossible creations. By a strong effort of the will, however, the original thread of the ideas may still be recovered, and the interlopers driven away. These lucid intervals successively become of shorter duration, and can be less frequently procured by a voluntary effort ; for the internal tempest becomes more and more violent, the torrent of disconnected ideas increases in power so as completely to arrest the attention, and the mind is gradually withdrawn altogether from the contemplation of external realities, being engrossed by the consciousness of its own internal workings. There is always preserved, however, a much greater amount of self-consciousness than exists in ordinary dreaming; the condition rather corresponding with that just referred to, in which the sleeper foioivs that he is dreaming. The succession of ideas has at first less of incoherence than in ordinary dreaming, the ideal events not departing so far from possible realities ; and the disorder of the mind is at first manifested in errors of sense, in false convictions, or in the predominance of one or more extravagant ideas. These ideas and convictions are generally not altogether of an imaginary character, but are called up by external impressions, which are erroneously interpreted by the perceptive faculties. The error of perception is remarkably shown in regard to time and space ; minutes seem i hours, hours are prolonged into years, and at last all idea of time seems obliterated, and past anil present are confounded together as in ordinary dreaming : and in like manner, streets appear of an interminable length, and the people at the other end seem to be at a vast distance. Still there is a certain con- sciousness of the deceptive nature of these illusions, which, if the dose be moderate, is never entirely lost. The effect of a full dose, however, is at last to produce the complete withdrawal of the ! mind from any distinct comprehension of ex- ternal things ; the power of the will over the current of thought is in like manner suspended, and the condition of the mind becomes the same in all essential particulars with that of the ordinary dreamer ; differing in this chiefly, that the feelings are more strongly ex- erted, and that they still take their tone almost entirely from external impressions. Thus, says M. Moreau*, “ It will be entirely dependent on the circumstances in which we are placed, the objects which strike the eyes, the words which fall on our ears, whether the most lively sentiments of gaiety or of sadness shall be produced, or passions of the most I; opposite nature shall be excited, sometimes with extraordinary violence ; for irritation * Du Hachiseh et de 1’ Alienation Mentale, Etudes Psychologiques, p. 67. SLEEP. shall pass rapidly into rage, dislike to hatred, and the desire of vengeance and the calmest affection to the most transporting passion. Fear becomes terror, courage is developed into rashness which nothing checks, and which seems not to be conscious of danger, and the most unfounded doubt or suspicion becomes a certainty. The mind has a tendency to exag- gerate everything, and the slightest impulse carries it along. Those who make use of the hachisch in the East, when they wish to give themselves up to the intoxication of the/«n- tasia, take great care to withdraw themselves from everything which could give to their de- lirium a tendency to melancholy, or excite in them anything else than feelings of pleasurable enjoyment. They profit by all the means which the dissolute manners of the East place at their disposal. It is in the midst of the harem, surrounded by their women, under the charm of music and of lascivious dances executed by the Almees, that they enjoy the intoxicating dawamesc ; and with the aid of superstition, they find themselves almost transported to the scene of the numberless marvels which the Prophet has collected in his Paradise.”* SOMNAMBULISM. Our history of sleep would be incomplete without some account of a state which is closely allied to it, though differing from it in several important particulars. The pheno- mena of somnambulism are so varied, that it is very difficult to frame any definition capable of including them all ; and we prefer charac- terising the state by saying that it may be con- sidered as an acted dream, — differing from or- dinary dreaming in the two following points. In the first place, the train of thought is more under the direction of sensations derived from without; and, secondly, the muscular system is so completely under the control of the mind, as not merely to give expression to its emotional states, but also to act in respon- dence to its volitions. As in dreaming, there would seem to be, in true somnambulism, a complete want of voluntary control over the current of thought, but there is not the same degree of mental activity; and in particular the operation of the associative principle is so much more restricted, that there is little or * The celebrated oriental scholar, M. Sylvestre de Sacy, appears to have made it pretty plain that our word assassin is derived from Hachiscliin, in the following- manner. It is well known that the term ■was originally employed in Syria, to designate the followers of the “ Old Man of the Mountain,” who were accustomed to devote themselves with blind obedience to the execution of the orders of their : chief, sacrificing themselves or others with equal readiness. Their education tended in every way to impress upon them this duty ; and as a reward for its performance, they were promised after death all i the sensual pleasures they could imagine, — a foretaste of these being every now and then given to them ; by intoxicating them with hachisch, in the midst of j scenes in which everything was provided to gratify their senses. In this manner, a sort of fanaticism 1 was gradually induced, which rendered them fit. i agents of the murderous designs of their master. 691 none of that incoherence or incongruity in the ideas brought up, which is so peculiar in ordi- nary dreaming. On the contrary, reasoning processes are often carried out with extraor- dinary clearness and correctness; the mind being intently fixed upon them to the exclu- sion of all other considerations. This exclu- siveness, indeed, is one of the most remarkable characteristics of the condition. Whilst the attention of the mind remains fixed upon any object, either perceived by the senses or brought up by the act of conception, nothing else is felt. Thus there may be complete in- sensibility to bodily pain, the somnambulist’s whole attention being given to that which is passing within the mind. Yet, in an instant, by directing the attention to the organs of sense, the anaesthesia may be succeeded by the most acute sensibility. So, again, when the attention is fixed upon a certain train of thought, whatever is spoken in harmony with it is heard and appreciated by the somnam- bulist ; but whatever is in discordance with it is entirely disregarded. The character of the intellectual operations partakes of this pecu- liarity. As just now stated, the reasoning processes are usually accurately and definitely carried on, so that the conclusion will be sound, provided that the data have been cor- rect. Thus, a mathematician will work out a difficult problem, or an orator will make a speech appropriate to a given subject. But the usual defect of the intellectual operations carried on in this condition is, that, owing to their very intensity, the attention is drawn off from the considerations which ought to modify them ; and thus it happens that the result is often palpably inconsistent with the teachings of ordinary experience, and will be admitted to be so by the somnambulist when the former are brought to his mind. The state of somnambulism may pass, on the one hand, into that of ordinary dreaming, so that it is difficult to draw the line between the two. Thus, the ordinary “talking in the sleep” may be referred to one or the other condition, according to the definition of each that we may adopt. In our own arrangement, they fall under the second head; because the vocal movements are expressions of the intel- lectual processes that are taking place in the mind ; and because, in most cases of this kind, the sleep-talker hears and comprehends what is said to him, provided that this harmonises with what is going on within, and will answer rationally, so as to sustain a conversation. Thus, we knew a young lady at school, who frequently began to talk after having been asleep an hour or two ; her ideas almost al ways ran upon the events of the previous day ; and if encouraged by leading questions addressed to her, she would give a very distinct and co- herent account of them ; frequently disclosing her own peccadilloes and those of her school- fellows, and expressing great penitence for the former, whilst she seemed to hesitate about making known the latter. To all ordinary sounds, however, she seemed perfectly insen- sible. A loud noise would awake her, but v v 2 692 SLEEP. was never perceived in the sleep-talking state; and if the interlocutor addressed to her any questions or observations that did not fall in with her train of thought, they were completely disregarded. By a little adroitness, however, she might be led to talk upon almost any subject; a transition being gradually made from one to another by means of leading questions. The well-known case of the officer, narrated by Dr. James Gregory, is one of the same in- termediate class; rather allied, in our appre- hension, to somnambulism than to ordinary dreaming. This gentleman, who served in the expedition to Louisburgh in 1758, was in the habit of acting his dreams ; and their course could be completely directed by whispering into his ear, especially if this was done by a friend with whose voice he was familiar; so that his companions in the transport were in the constant habit of amusing themselves at his expense. At one time they conducted him through the whole progress of a quarrel, which ended in a duel ; and when the parties were supposed to be met, a pistol was put into his hand, which he fired, and was awakened by the report. On another occasion they found him asleep on the top of a locker or bunker in the cabin, when they made him believe he had fallen overboard, and exhorted him to save himself by swimming. He imme- diately imitated all the motions of swimming. They then told him that a shark was pur- suing him, and entreated him to dive for his life. He instantly did so, with such force as to throw himself entirely from the locker upon the cabin-floor, by which he was much bruised, and awakened of course. After the landing of the army at Louisburgh, his friends found him one day asleep in his tent, and evidently much annoyed by the cannonading. They then made him believe that he was engaged, when he expressed great fear, and showed an evident disposition to run away. Against this they remonstrated; but, at the same time, in- creased his fears, by imitating the groans of the wounded and the dying; and when he asked, as he often did, who was down, they named his particular friends. At last they told him that the man next himself in the line had fallen, when he instantly sprung from his bed, rushed out of the tent, and was roused from his danger and his dream together, by falling over the tent- ropes. After these experiments, he had no distinct recollection of his dreams, but only a confused feeling of oppression and fatigue ; and used to tell his friends that he was sure they had been playing some trick upon him. This is another point of conformity with somnam- bulism ; one of whose most distinctive pecu- liarities it is, that neither the trains of thought nor any of the events of the somnambulistic state are remembered in the ordinary waking condition, though the impression of the feelings strongly excited during that state, is some- times continued. Both the trains of thought and the events of the somnambulistic state, however, are frequently remembered with the utmost vividness on the recurrence of that state, even at a very distant interval : and of the interval, however long it may have been, there is no consciousness whatever. The same thing, but more rarely, occurs in dreaming ; the dreamer sometimes recollecting a previous dream, and even taking up and continuing its thread, although he could not in the least retrace it in his waking state. A remarkable case of spontaneous somnam- bulism, which occurred within our own ex- perience, wdl serve to illustrate many of the most characteristic features of the condition in question. The subject of it was a young lady of highly nervous temperament ; and the affection occurred in the course of a long and trying illness, in which almost every form of hysteria, simulating tetanus, epilepsy, coma, and paralysis, had successively presented itself. Although natural somnambulism ordinarily arises out of ordinary sleep, yet in this instance the patient usually passed into the somnam- bulistic condition from the waking state ; the transition being immediately manifested by the peculiar expression of the countenance. In this condition her ideas were at first entirely fixed upon one subject — the death of her only brother, which had occurred some years pre- viously. To this brother she had been very strongly attached ; she had nursed him in iiis last illness ; and it was perhaps the return of the anniversary of his death about the time when the somnambulism first occurred, that gave to her thoughts that particular direction. She JJ talked constantly of him, retraced all the cir- cumstances of his illness, and was unconscious of anything that was said to her which had not direct reference to this subject. On one oc- casion she mistook her sister’s husband for her lost brother ; imagined that he was come from heaven to visit her; and kept up a long conversation with him under this impression. This conversation was perfectly rational on her side, allowance being made for the funda- mental errors of her data. Thus, she begged her supposed brother to pray with her; and on his repeating the Lord’s Prayer, she interrupted him after the sentence “ forgive us our tres- passes,” with the remark, “ But you need not pray thus ; your sins are already forgiven.” Although her eyes were open, she recognised no one in this state, not even her own sister, who, it should lie mentioned, had not been at home at the time of her brother’s illness. On another occasion, it happened that, when she passed into this condition, her sister, who was present, was wearing a locket, containing some of their deceased brother’s hair. As soon as she perceived this locket, she made a violent snatch at it. and would not be satisfied until she had got it into her own possession, when she began jj to talk to it in the most endearing and even extravagant terms. Her recognition of this | locket, when she did not perceive that her sister was the wearer of it, was a very curious fact, which may be explained in two ways,# each of them in accordance with the known laws of somnambulism. Either the concen- tration of her thoughts on this one subject caused her to remember only that which was j| SLEEP. 693 immediately connected with her brother ; and her unconsciousness of the presence of her sister might be due to the absence of the latter at the time of his death, which caused her to be less connected with him in the thoughts of the somnambulist: — or it may have happened that she was directed to this locket by the sense of smell, which is fre- quently exalted in a very remarkable degree in the somnambulistic state. (See Smell) Her feelings were so strongly excited by the posses- sion of the locket, that it was judged prudent to check their continuance; and as she was inaccessible to all entreaties on the subject, force was employed to obtain it from her. She was so determined, however, not to relinquish it, and was so angry at the gentle violence used, that it was found necessary to abandon the attempt; and she became calmer after a time, and at last passed off into ordinary sleep, which was in her case the successor, instead of being (as it usually is) the predecessor, of the somnambulistic state. Before going to sleep, however, she placed the locket under her pillow, remarking, “ Now I have hid it safely, and they shall not take it from me.” On awaking in the morning, she had not the slightest conscious- ness of what had passed ; but the impression of the excited feelings remained ; for she remarked to her sister, — “ I cannot tell what it is that makes me feel so ; but every time that S comes near me, I have a kind of shuddering sensation ; ” — the individual named being a servant, whose constant at- tention to her had given rise to a feeling of strong attachment on the side of the invalid, but who had been the chief actor in the scene of the previous evening. This feeling wore oft’ in the course of a day or two. A few days afterwards, the somnambulism again recurred ; and being upon her bed at the time, she immediately began to search for the locket under her pillow. In consequence of its having been removed in the interval (in order that she might not, by accidentally finding it, be led to inquire into the cause of its presence there, of which it was thought better to keep her in ignorance), she was unable to find it ; at which she expressed great disappointment, and continued feeling for it, with the remark, “ It must be there ; 1 put it there myself a few minutes ago; and no one can have taken it away.” In this state, the presence of S renewed her previous feelings of anger ; and it was only by sending S out of the room that she could be calmed and induced to sleep. This patient was the subject of many sub- sequent attacks, in every one of which the anger against S revived; until the current of thought changed, no longer running exclu- sively upon what related to her brother, but becoming capable of direction by suggestions of various kinds presented to her mind, either in conversation, or, more directly, through the several organs of sense. On one occasion, the attack having come on whilst she was alone, she managed to make her way down stairs, along a passage, and out into the garden by a back-door, although completely paraplegic,— a very curious instance of sleep- walking. So nearly did her condition, in some of these attacks, approach the waking state, that the case might then be almost regarded as one of double consciousness, — that very curious affection, of which the sub- ject seems to lead two distinct lives, A and B, in neither remembering what takes place in the other, but each state being, as it were, continuous with itself. The preceding case is well adapted to illustrate the general characters of the som- nambulistic condition : we have now to notice some of those peculiar phenomena which are presented in individual cases. The first of these to which we shall advert, is the extraordinary exaltation of the sensibility to external impressions through one or more of the organs of sense; which would seem to result, in some instances, from the concentra- tion of the attention upon that one class of impressions, but which, in other cases, is independent of any such state of attention.* We have ourselves been particularly struck with this, in the somnambulism induced by the “ hypnotic ” process of Mr. Braid, to which we shall presently refer. We have seen unequivocal proof that the sense of smell has been exalted to an acuteness ac least equalling that of the most keen nosed ruminant or carnivorous animal ; that the sense of hearing has been rendered equally acute ; and that the sense of touch has been exalted, especially in regard to temperature, to a degree that would be scarcely credible, were not the phenomena in perfect keeping with the exaltation of the other senses. We are not aware that the sense of sight has ever been thus acted on. In most som- nambulists it is altogether suspended ; and those who claim to possess the power of clairvoyance, reading words inclosed in opaque boxes, &c., do not refer their power of doing so to any unusual acuteness of their visual organs, but attribute it to the develop- ment of an entirely new faculty, for the operation of which any such optical instru- ment as the eye is altogether unnecessary. Among the senses most commonly exalted in somnambulism, is that “muscular sense” by which all our voluntary movements are guided ; and this seems to be so much in- creased in acuteness, as quite to replace the visual sense, in the performance of many of those operations for which sight is ordinarily requisite. Thus we find that sleep-walkers make their way over the roofs of houses, * The young lady whose case we have just de- tailed, exhibited, in a former attack of nervous disorder, a most extraordinary acuteness of the au- ditory sense, so that it was difficult to prevent her from hearing everything that passed in the house. Of a conversation held in an ordinary tone, in a room two stories below, she could hear every word as distinctly as if it had passed in her own chamber. Yet she did not suffer pain, as might have been expected, from the excessive loudness of ordinary sounds. V Y 3 694 SLEEP. steadily traverse narrow planks, and even clamber precipices; and this with far less hesitation than they would do in the waking state. The fact seems to be, that they are utterly unconscious of the danger they are incurring ; and that the whole attention being fixed without any distraction upon the indications of the muscular sense, the requi- site movements are performed under its guidance with steadiness and certainty. So, again, it is well known that somnambulists will write with their usual degree of neatness and regularity, when prompted to do so either by their own train of thought, or hy some suggestion from without ; and this, when it is perfectly certain that they cannot see. We have ourselves witnessed this in hypnotic experiments on two individuals, and made quite sure that vision could not be affording any assistance, by holding a large book between the eyes and hand of the writer. Not only were the lines well written, and at the proper distances, but the i’ s were dotted and the t' s crossed ; and in one instance, the writter went back half a line to make a correction, crossing off a word, and writing another above it, with as much correctness as if he had been guided by vision. The guidance of the muscular sense in this case may be compared to that which we ourselves receive from it, when ascending or descend- ing a pair of stairs, or traversing a passage, to which we have previously been accustomed, in the dark ; we know when we have come to the end, without having counted our steps, or in any way observed our progress, simply by the information we receive through the muscular sense. To the suspension, com- plete or partial, of the activity of one or more of the organs of sense, which may occur spon- taneously, or may be induced by calling off the attention from it, reference has already been made. The next point to be noticed is the readiness with which the train of thought may be guided, during the state of somnambulism, by the principle of suggestion. This is more, perhaps, the case in artificial or induced than in natural somnambulism ; for in the latter there is fre- quently, as already pointed out, some domi- nant idea or set of ideas, from which the attention of the somnambulist cannot easily be distracted, In the former, the mind is like a weathercock, without the least fixity or self-control, but liable to be turned in any direction by the impressions to which it is subjected. It is one of the most curious and important of Mr. Braid’s discoveries, that the suggestions conveyed through the muscular sense are among the most potent of any in determining the current of thought. Let the face, body, or limbs be brought into the atti- tude expressive of any particular feeling, or into a condition at all corresponding with that in which they would be placed for the performance of any voluntary action, and the corresponding mental state is at once called up. Thus, if the hand be placed upon the vertex, the somnambulist will frequently, of his own accord, draw his body up to its fullest height, anil throw his head slightly back; his | countenance then assumes an expression of the most lofty pride, and his whole mind is obviously possessed by the feeling. Where | the first action does not of itself call forth the rest, it is sufficient to straighten the legs and spine, and to throw the head somewhat back, !' to arouse the feeling and the corresponding expression to its full intensity. During the most complete domination of this emotion, let the head be bent forward, and the body and limbs gently flexed ; and the most pro- found humility then takes its place. So, again, if the angles of the mouth be gently separated from one another, as in laughter, a hilarious disposition is immediately generated ; and this may be immediately made to give :j place to moroseness, by drawing the eyebrows towards each other and downwards upon the nose, as in frowning. Not only have we witnessed all these effects repeatedly pro- duced upon numerous “ hypnotised ” sub- jects, but we have been assured by a most I intelligent friend who has paid special atten- tion to the psychological part of this enquiry, that having subjected himself to Mr. Braid's manipulations, and been only partially thrown into the “hypnotic” state, he distinctly re- members everything that was done, and can retrace the uncontrollable effect upon his state of mind which was produced by this management of his muscular apparatus. So, again, not merely emotional states but definite ideas are thus excitable. Thus, if the hand be raised above the head, and the fingers are flexed upon the palm, the idea of I climbing, swinging, or pulling at a rope is called up,; if, on the other hand, the fingers are flexed when the arm is hanging down at the side, the idea excited is that of lifting a weight ; and if the same be done when the arm is advanced forwards in the position of striking a blow, the idea of fighting is at once aroused, and the somnambulist is very apt to put it into immediate execution. On one occasion on which we witnessed this result, a violent blow was struck, which chanced to | alight upon a second somnambulist within reach ; his combativeness being thereby ex- cited, the two closed, and began to belabour one another with such energy, that they were with difficulty separated. Although their pas- \ sions were at the moment so strongly excited, that even when separated they continued to utter furious denunciations against each other, yet a little discreet manipulation of their muscles soon calmed them, and put them into perfect good humour. The power of the operator, in regulating the state of mind ol such somnambulists, is almost unlimited ; and surpasses the credibility of those who do not discern the very simple principle on which it 1 is exercised. The facility with which parti- cular feelings or ideas may thus be excited, j will of course be dependent in part on the i previous character and habits of the somnam- bulist. Again, a very uncommon degree of power SLEEP. may be determined to particular muscles, as Mr. Braid has shown, either by a suggestion (so to speak) applied directly to themselves, or by the induction of such a mental state as shall be most fitted to call them into energetic operation. Thus the extensor muscles of a limb may be excited to contraction by gently rubbing or pressing the surface above them ; and this contraction may not merely raise the limb, but may keep it fixed in a cataleptiform manner for a much longer time than anv voluntary effort could accomplish. This con- traction may be caused to give way at any moment, by gently wafting a current of air over the same surface, which seems to call off the attention from the muscles to the skin. In order to throw an extraordinary degree of power into a group of muscles by a mental process, all that is required is to suggest the action, and to assure the somnambulist that it can be accomplished with the greatest facility if he will only determine to do it. Thus, we have seen one of Mr. Braid’s hypnotised sub- jects, a man remarkable for the poverty of his muscular development, lift a twenty-eight pound weight upon his little finger alone, and even swing it round his head, — upon being assured that it was as light as a feather. We have every reason to believe that the personal character of this individual placed him above the suspicion of deceit ; and it is obvious that if he had practised such a feat (which very few, even of the strongest men, could accomplish without practice), the effect would have been visible in his muscular development. The same individual declared himself altogether unable to raise a handker- chief from the table, after many apparently strenuous efforts; having been assured that its weight was too great for him to move. Of course, there was not an equal proof of the absence of deception in this seeond case as in the first; but if the reality of the first be ad- mitted, there need be no difficulty in the re- ception of the second, since both are manifes- tations of that mental condition which has been shown to be so characteristic of this state, — the possession of the mind by a dominant idea, which, when infused into it (as it were) by the principle of suggestion, directs the bodily movements, and is not cor- rected by the teachings of ordinary experience, or even by present sensations, if the mental assurance be strong enough to cause these to be disregarded. Of the causes of somnambulism, no very definite account can be given. In some persons this state recurs frequently, or even habitually ; in others occasionally. In the case formerly detailed, its access might gener- ally be traced to some strong mental emotion. Those in whom it presents itself spontaneously are said to be natural somnambulists ; but it may be induced, not merely in them, but in others who have manifested no predisposition to it, by certain artificial procedures. In many cases this may be effected through the mind alone, the simple expectation of the result being sufficient to bring it about. Thus 695 the Abbe Faria was accustomed to induce somnambulism by placing his patient in an arm-chair, and then, after telling him to shut his eyes and collect himself, pronouncing in a strong voice and imperative tone the word “ dormez,” which generally produced on the individual an impression sufficiently strong to give a slight shock, and occasion warmth, transpiration, and sometimes somnambulism. — The following case is another illustration of the effect of this state of expectation, acting in concurrence with a fixed position. The subject of it was a lady w'ho had pre- viously shown great susceptibility to the “ mesmeric ” and “ hypnotic ” processes. “ We now requested our patient to rest quietly at the fire-place, to think of just what she liked, and look where she pleased, except at ourselves, who retreated behind her chair, saying that a new mode was about to be tried, and that her turning round would disturb the process. We very composedly took up a volume which lay on the table, and amused ourselves with it for about five minutes ; when, on raising our eyes, we could see, by the excited features of other members of a little party that were assembled, that the young lady was once more magne- tised. We were informed by those who had attentively watched her during the progress of our little stratagem, that all had been, in every respect, just as before. The lady herself, before she was undeceived, expressed a distinct consciousness of having felt our unseen passes streaming down the neck.”* Perhaps the most effectual of all modes of inducing somnambulism is that discovered by Mr. Braid, and practised extensively by him under the designation of hypnotism. j- The following is his description of his mode of in- ducing it, and of the phenomena attending its production. “ Take any bright object (I gene- rally use my lancet-case) between the thumb and fore and middle fingers of the left hand ; hold it from about eight to fifteen inches from the eyes, at such position above the forehead as may be necessary to produce the greatest possible strain upon the eyes and eyelids, and enable the patient to maintain a steady fixed stare at the object. The patient must be made to understand that he is to keep the eyes steadily fixed on the object, and the mind riveted on the idea of that one object. It will be observed that, owing to the con- sensual adjustment of the eyes, the pupils will be at first contracted ; they will shortly begin to dilate, and after they have done so to a considerable extent, and have assumed a wavy motion, if the fore and middle fingers of the right hand, extended and a little separated, are carried from the object towards the eyes, most probably the eyelids will close invo- luntarily, with a vibratory motion. . . . After ten or fifteen seconds have elapsed, by gently elevating the arms and legs, it will be found * Brit, and For. Med. Rev., vol. six. p. 477. f Neurypnology, or the Rationale of Nervous Sleep, considered in relation with Animal Magnetism, &c., by James Braid, M. R. C. S. E., &c. Y Y I 696 SLEEP. that the patient has a disposition to retain them in the situation in which the)’ have been placed, if he is intensely affected. If this is not the case, in a soft tone of voice desire him to retain the limbs in the extended posi- tion, and thus the pulse will speedily become greatly accelerated, and the limbs, in process of time, will become quite rigid and involun- tarily fixed. It will also be found that all the organs of special sense, excepting sight, in- cluding heat and cold, and muscular motion or resistance, and certain mental faculties, are at first prodigiously exalted ; such as happens with regard to the primary effects of opium, wine, and spirits. After a certain point, however, this exaltation of function is fol- lowed by a state of depression, far greater than the torpor of natural sleep. From the state of the most profound torpor of the organs of special sense, and tonic rigidity of the muscles, they may at this stage be in- stantly restored to the opposite condition of extreme mobility and exalted sensibility, by directing a current of air against the organ or organs we wish to excite to action, or the muscles we wish to render limber, and which had been in the cataleptiform state. By mere repose the senses wdl speedily merge into the original condition again.” We have our- selves frequently witnessed the induction of somnambulism after this method ; and whilst fully admitting its potency, we are bound to say that the almost invariable success which it has in the hands of Mr. Braid himself, appears partly due to the mental condition of rlie patient, who is usually predisposed to the “ hypnotic ” state by the expectation of its certain production, and by the assurance of a man of determined will that it cannot be resisted. When the hypnotic state, however, has been induced a few times in the manner just described, the subject can usually send himself to sleep very readily by looking at his own finger, brought sufficiently near the eyes to occasion a sensible convergence of their axes ; or even by simply standing still, and fixing the eyes on a distant point. In all cases, the fixation of the eyes is the circum- stance of most importance ; although the withdrawal of other stimuli has a decided influence in favouring the production of the effect. The peculiar condition of the muscular sense, as felt through the ophthalmic branch of the fifth pair, seems to have a closer relation with the subsequent state than has the con- dition of the visual sense; for the same effect may be produced at night, or in blind persons, if the eyes can be kept in a fixed position, especially in one that produces a feeling of muscular tension. And it seems to be in facilitating this, that the sense of sight comes into play in the operation just de- scribed. How far the mode in which the somnambulism is produced has an influence upon its phenomena, it may not be very easy to determine. For an account of these pe- culiarities, we must refer to Mr. Braid’s treatise already quoted ; but we may cite the following, as having ourselves repeatedly witnessed it and satisfied ourselves of its reality. “ The remarkable fact that the whole senses may have been in a state of profound torpor, and the body in a state of rigidity, and yet by very gentle pressure over the eye-balls the patient shall be instantly roused to the waking condition, as regards all the senses and mobility of the head and neck, in short, to all parts supplied with nerves originating above the origin of the fifth pair, and those inosculating with them, — whilst they will not be affected by simple mecha- nical appliance to other organs of sense, — is a striking proof that there exists some remarkable connection between the state of the eyes, and condition of the brain and spinal cord, during the hypnotic state. Another remarkable proof to the same effect is this ; Supposing the same state of torpor of all the senses, and rigidity of the body and limbs, to exist, a puff of air or a gentle pressure against one eye will restore sight to that eye, and sense and mobility to one half of the body — the same side as the eye operated on ; — but will leave the other eye insensible, and the other half of the body rigid and torpid as before.” * We consider that the experimental re- searches of Mr. Braid throw more light than has been derived from any other source upon tlie phenomena of Mesmerism . That there is much of reality mixed up with much impos- ture in these phenomena, is a conclusion at which most candid persons have arrived who have given their attention to them ; and we have little doubt that a searching investiga- tion, carried on under the guidance of his results, would lead to something like a correct discrimination between the two. The induc- tion of mesmeric somnambulism appears to us to be fully explicable by the facts we have previously stated, as to the influence of the mental condition of the patient, — namely, the state of expectation, and the additional confidence derived from the mental impres- sion produced by the. operator, — and as to the effect of the fixation of vision. The ordi- nary phenomena of the mesmeric somnam- bulism itself are in most respects identical with those of hypnotism, except in this parti- cular,— that there seems to he a peculiar relation between the somnambulist and the mesmeriser, which does not exist between the somnambulist and any other individual, excepting one who is en rapport with the mesmeriser. This relationship may perhaps be not unreasonably regarded as the result of a dominant idea, which possessed the mind at the moment of falling asleep, and which con- tinued to influence it so long as the somnam- bulism lasts. We have examined into the history of many cases, in which it was affirmed that mesmeric sleep was induced without any consciousness on the part of the subject of it that any influence was being exercised; but we have never been able to satisfy ourselves that such was unequivocally the case. When the patient was expecting the per for man ce; * Op. cit. p. 64. note. SLEEP. 697 and was waiting in quiescence for its com- mencement, the expectation alone was suffi- cient to induce the sleep. When the patient had no such expectation, all attempts to pro- duce the sleep, that have come to our know- ledge, have completely failed. Hence we are strongly inclined to the belief that the rela- tion between the mesmeriser and the som- nambulist is one of a purely mental character, and not the result of any new physical power. With regard to what have been termed the “ higher phenomena” of mesmerism, we be- lieve that without regarding them as the result of intentional deception, most of them are capable of receiving a very simple expla- nation on the principles already laid down, — namely, that in the state of somnambulism the senses, or some of them, are often en- dowed with a wonderful acuteness, which causes the mind to be acted on by impressions that might be affirmed to be too faint to be perceived ; and that these impressions will suggest trains of thought, anti give rise to respondent actions, which are frequently of a kind that the will could not produce. As to the reality of the so-called clairvoyance , re- peated personal examination has led us to a negative conclusion. The sources of fallacy arising from the causes we have mentioned, as also from the tendency on the part of the bystanders to afford assistance by asking “ suggestive” or “ leading questions,” and from their disposition to interpret the least shadow of a resemblance into a complete coincidence, are such as greatly to diminish the wonder that a firm belief in the reality of these phenomena should be entertained by many persons of excellent judgment and great discrimination and acuteness as to all ordinary matters. A state in most respects corresponding with natural somnambulism is frequently in- duced by the inhalation of ether, chloroform, and other anaesthetic agents. Instead of being completely comatose, the patient, though quite unconscious of pain, may be awake to ex- ternal impressions received through some of his organs of sense, so as during an operation to obey the directions given him in order to facilitate its performance ; and yet he shall be completely unaware of what has taken place when the effects of the anaesthetic agent have gone off But even the sense of pain may not be extinguished, and the patient may scream and struggle even more violently than in the waking state ; and yet the whole is subsequently forgotten, or is remembered only as a troubled dream. It was further to be noticed that, during the employment of ether, the state of the nervous system induced by it appeared to be much influenced by the pre- vious degree of confidence entertained by the patient as to its results. The more potent action of the chloroform, however, has pre- vented this influence from being so apparent. (IE. B. Carpenter.) SMELL. — The sense through which we take cognizance of odours. Of the nature of odorous emanations no- thing is certainly known. They are generally supposed to consist of material particles of extreme minuteness, detached from the odor- ous body, and dissolved or suspended in the air. This idea derives its chief support from the facts that most odorous substances are volatile, that is, their loss of weight, when exposed to the air, shows that their particles really diffuse themselves through it, — that most strongly odorous substances are ex- tremely volatile — and that circumstances which increase the volatility of such substances also augment their odorous powers. These gene- ral statements, however, are not without their exceptions. Thus, in the first place, we do not find that many gaseous substances are truly odorous ; the pungent, irritating qualities, by which many of them are distinguished, not being perceived through the sense of smell but through that of touch. Again, although it is true that a great number of volatile liquids are odorous, the strength of their scent bears no constant proportion to their respec- tive volatility ; and water, which is so con- stantly diffused through the air, has no odor- ous property. And with regard to solids, we find that although some of those which are most strongly odorous are also volatile (such as camphor), yet this is not by any means universally the case ; for it has been proved by experiment that no diminution in weight can be ascertained to take place in musk or amber, although they have been freely exposed to the atmosphere for many years, and have imparted their perfume to an almost incalculable volume of air. These considerations have led some philosophers to suppose that odorous emanations are not material, but dynamical: — in other words, that the impressions made upon our olfactory organ do not result from the contact of dif- fused particles detached from the odorous body ; but that they are 'effected by a change propagated through the atmosphere or other medium, in the same manner as sound is pro- duced by undulations that originate in the sonorous body, and are transmitted onwards, through some material medium, to the organ of hearing. There are strong objections, how- ever, to this hypothesis. In the first place, we find that odours are not perceived unless the air, gas, or liquid in contact with the olfactory surface is, or has been, in direct continuity with the odorous body ; the inter- position of any substance which prevents the actual passage of the odoriferous medium being sufficient to prevent the transmission of the odour. This is by no means the case in regard to sound, or to any other agent that is known to be dynamically propagated ; for we find many substances which are capable of conducting these agents, that is, of transmitting their influence through unlimited spaces; and this may be accomplished in spite of any number of interruptions in their continuity, provided the chain of conducting substances be complete. Thus, sonorous vibrations may be transmitted from air to liquids, from liquids 698 SMELL. to solids, from air to solids, from solids to air, &e. ; and many such changes usually take place, before the vibrations originating in a sonorous body are communicated to the sen- tient extremities of the auditory nerve. The same is the case with heat, light, electricity, and other agents whose transmission is be- lieved to be dynamical : that it is not the case in regard to odorous emanations must be regarded, therefore, as a powerful argument against the idea of their dynamical nature. Another argument may be derived from the well-known fact, that odorous emanations re- quire such a time for their propagation, as corresponds rather with the diffusion of the odoriferous medium itself, than with the mere conduction of vibrations. Thus, in a house in which free communication is established throughout by passages, staircases, &c., but in which the course of air is not very direct from one part to another, any strong odour set free in one spot will be gradually diffused through the whole house, the rapidity being governed by the circumstances which favour or obstruct the movement of air. On the other hand, the transmission of sonorous un- dulations, which merely throw the air into vibration, is not dependent upon its move- ment, and is, indeed, but little influenced by it. This argument is, perhaps, yet more cogent than the former, and may be regarded as conclusive against the dynamical theory of odours. It is not difficult to explain many of the apparent inconsistencies which attend the material theory. The varieties of the olfac- tive power among human beings are quite sufficient to prove, that a substance which is strongly odorous to one individual may not produce any impression on the smell of an- other, whose scent for other substances may nevertheless be very acute. And there is strong reason to believe that there is a great diversity in this respect amongst dif- ferent species of animals, some appearing en- tirely insensible to odours which strongly affect others. That rue do not appreciate an odour, therefore, is no proof of its non-exist- ence ; and we have no right to say of any volatile or gaseous substances, that they are not odorous, but simply that they are not odorous to us. Again, the sense of smell, like the other senses, is rather relative than •positive ■, that is to say, it rather estimates a change in the condition of the surrounding medium, than its actual permanent state. This is fully proved by the fact that persons who habitually dwell amongst odours of any one kind, become, in time, entirely insensible to them, although their olfactive sense may re- main of its full acuteness in regard to any different scent. This being the case, we at once perceive that water, oxygen, nitrogen, and carbonic acid could not, in accordance with the general laws of sensation, possess any odour to animals whose organs of smell are constantly imbued with them. We shall presently find that the moisture of the olfac- tory membrane is a necessary condition of its functional power ; and thus neither fishes, which have their olfactory surface con- stantly bathed in water, nor air-breathing ani- mals, whose pituitary membrane is lubricated with it, could take cognisance of any odorous properties which it might really possess. In like manner, the nasal cavities of animals being continually filled with a mixture of oxygen, hydrogen, and carbonic acid, these gases cannot excite the olfactive sense ; whilst I on the other hand, we can easily imagine that if animals were adapted to breathe hydrogen or its strongly odorous compounds, they |j would be insensible to the latter, whilst they might distinguish oxygen, nitrogen, or carbo- nic acid by their respective odours, just as | readily as ive distinguish phosphu retted, sul- phuretted, or carburetted hydrogen. Although it is through the atmosphere ( that odorous emanations are most readily conveyed, yet there can be no reasonable doubt that they may be transmitted through water also. Thus we find fishes provided | with a complex organ of smell, which seems to be of considerable importance in directing them towards their prey. This may be infer- red, not merely from the fact that the olfactive !; ganglia and nerves are of large size relatively to the rest of the encephalon, but also from the circumstance, well known to fishermen, that many fish are particularly attracted by odorous bait. Some anglers are even in the habit of scenting their bait with essential j oils, in order to render it more alluring. The general structure of the organ of smell in man has already been described (Nosb,); but some particulars recently ascer- tained by Messrs. Todd and Bowman re- specting the minute anatomy of the pituitary membrane, and the structure and distribution of the olfactory nerve, are too important to be passed by. That the true sense of smell is specially, if not exclusively, the endowment of the upper portion of the organ, has been inferred by anatomists from the limited dis- tribution of the olfactory nerve, and by phy- siologists from the fact that odours are only perceived strongly when the odoriferous air is drawn into the upper part of the cavity. The lower part of the nasal cavity is pro- perly to be regarded as the orifice of the respiratory passages : it is extremely sensitive j to irritants , but it does not participate in the discrimination of odours properly so called ; and its mucous membrane is covered with a ciliated columnar epithelium. On the other hand, the limits of the olfactive region “ are distinctly marked by a more or less rich sienna-brown tint of the epithelium, and by a remarkable increase in the thickness of this structure compared with the ciliated region below ; so much so, that it forms an opaque soft pulp upon the surface of the membrane, very different from the delicate, very trans- parent film of the sinuses and lower spongy bones. The epithelium, indeed, here quite alters its character, being no longer ciliated, but composed of an aggregation of superposed nucleated particles, of pretty uniform appear- SMELL. 699 ance throughout ; except that, in many in- stances, a layer of those lying deepest, or almost deepest, is of a darker colour than the rest, from the brown pigment contained in the cells. These epithelial particles, then, are not ciliated ; and they form a thick, soft, and pulpy stratum, resting on the basement membrane. The deepest layer often adheres after the others are washed away.” The vessels of the olfactive membrane in the fetus present a regular series of papillary loops ; but these cannot be seen in the adult. “ The olfactory filaments form a considerable part of the entire thickness of the membrane, and differ widely from the ordinary cerebral nerves in structure. They contain no white substance of Schwann, are not divisible into elementary fibrillae, are nucleated and finely granular in texture, and are invested with a sheath of homogenous membrane.” These nerves thus rather correspond with the gela- tinous fibres, than with the ordinary tubular fibres of the trunks and branches of true nerves ; and they are regarded by the authors as direct continuations of the vesicular matter of the olfactory bulb or ganglion . “ Although these nucleated olfactory filaments lie in great abundance under the mucous membrane of the olfactory region, we have been quite foiled in our attempts to trace their ultimate distribution in the membrane, and the diffi- culty is attributable to their want of the characteristic white substance. Their elon- gated nuclei render the larger branches un- mistakeable ; but if these become resolved at last into fibrous elements, the nuclei cease to be distinct from those of the numerous nu- cleated tissues which they traverse.” “ We are averse from speculating prematurely on the meaning of anatomical facts ; but as some hypothesis will intrude itself, we would ven- ture to hint that the amalgamation of the elements of the peripheral part of the nervous apparatus in the larger branches, and probably' in the most remote distribution, as well as the nucleated character indicative of an essential continuity of tissue with the vesi- cular matter of the lobe, are in accordance with the oneness of the sensation resulting from simultaneous impressions on different parts of this organ of sense, and seem to show that it would be most correct to speak of the first pair of nerves as a portion of the nervous centre put forward beyond the cra- nium, in order that it may there receive, as at first hand, the impressions of which the mind is to become cognisant.”* It has also been remarked by the same excel- lent observers j-, that on the septum narium and spongy bones bounding the direct pas- sage from the nostrils to the throat, the lining membrane is rendered thick and spongy by the presence of ample and capacious sub- mucous plexus of both arteries and veins, of which the latter are by far the larger and * Physiological Anatomy and Physiology of Man, vol. ii. pp. o — 11. f Op. c it. p. 3. more tortuous. And they surmise, with much probability, that the chief use of these may be to impart warmth to the air, before it enters the proper olfactive portion of the cavity; as well as to afford a copious supply of moisture, which may be exhaled by the abundant glandulce seated in the membrane. “ The remarkable complexity of the lower turbinated bones in animals with active scent, without any ascertained distribution of the olfactory nerves upon them, has given coun- tenance to the supposition that the fifth nerve may possess some olfactory endowment, and seems not to have been explained by those who rejected that idea. If considered as accessory to the perfection of the sense in the w'ay above alluded to, this striking arrangement will be found consistent with the view which thus limits the power of smell to the first pair of nerves.” * The olfactive organ, in other air-breathing Vertebrata, corresponds with that of man in all the essential particulars of its structure ; being a cavity opening anteriorly upon the face by the external or anterior nares, and posteriorly into the upper part of the pharynx by the internal or posterior nares. It may thus be considered as the entrance of the respi- ratory passages, which is dilated for the ex- tension of the olfactive membrane ; or, per- haps, it would be more correct to speak of it as a diverticulum from the commencement of the respiratory tube, since, as we have seen, the proper olfactive organ does not extend into that portion of the cavity which is placed in a direct line between the anterior and pos- terior nares. The development of the olfac- tive organ, as measured by the size of the olfactory ganglia and nerves, and by the ex- tent of the surface over which these are dis- tributed, varies greatly in different tribes ; and details must be sought on this subject under the respective names of the classes and orders of vertebrata. The chief departure from the ordinary type is observable in the case of the Cetacea, in which the nasal cavity is almost entirely devoted to the purposes of respiration, and to the ejection of the water taken in by the mouth with the food. To animals which seek their prey in the water, an organ of smell, adapted to take cognisance of odorous emanations contained in the inspired air, would obviously be entirely useless ; and it is probable that whatever olfactive power they possess is called into exercise by the passage of the water that is spouted through the nos- tril. The ordinary statement that the Cetacea are entirely destitute of olfactive ganglia and nerves, and that they must therefore be en- tirely devoid of the sense of smell, is true only of the DelpInnidcB, or that division of the order which includes the dolphins and porpoises ; for the BalcemdcE , or proper whales, do possess olfactive nerves, although these are comparatively of small size; and in the Manatidce , or herbivorous whales, which properly belong rather to the Pachydermata Op. cit. p. 12. 700 SMELL. than to the Cetacea, the olfactive apparatus is formed after the usual type. In Fishes, however, the plan is altogether changed, the organ of smell being no longer connected with the respiratory passages, but disposed in a cavity peculiar to itself, which opens externally by anterior nares, but has no internal communication by means of posterior orifices. No distinct organ of smell has yet been dis- covered in the Dibranehiate Cephalopoda; but in the Nautilus, a peculiar laminated orcran, strongly resembling the olfactive organ of fish, has been considered by Prof. Owen as an olfactory apparatus. The inferior Mol- lusca would seem to be altogether destitute of special organs of smell ; but as there is much reason to believe that some of them, espe- cially the terrestrial Gasteropods, are guided to their food by its scent, it would not seem improbable that some part of the soft spongy glandular mantle, in which the entire body is enveloped, may be adapted to take cogni- zance of odorous emanations ; or that in the air-breathing species, the entrance to the re- spiratory sac should be endowed with a low degree of this power. There is ample reason to infer, from ob- servations of the actions of Insects, that these animals possess the olfactive power in no in- considerable degree ; and yet no special organ for this sense has hitherto been satisfactorily made out. That many insects are guided to their food, to the proper nidus for their eggs, and to the opposite sex of their own species, and are even informed of the proximity of their natural enemies, by odorous emanations, can scarcely be doubted by any one who watch.es their habits, and who experiments upon their actions under a variety of circumstances. Thus, the flesh-fly will be attracted by the odour of decomposing meat, when this is completely hid from its sight ; and will depo- sit its eggs on the envelope with which it may be covered. On the other hand, the same insect is deceived by the odour of the Stapelia , or carrion-flower, and is led to deposit its eggs in its petals. Again, many male insects will show that they are aware of the prox- imity of their females, when the latter are shut up in boxes, so as to he hid from their sight, and utter no sound. And in like manner, when a predaceous insect or spider is shut up in a box that gives a sufficiently free pas- sage to air, the small insects on which it preys will manifest their alarm at its proximity, and will endeavour to make their escape. Some entomologists have supposed the seat of the olfactory sense of insects to be in their an- tennas, others in the palpi, and others in the entrances to the air-tubes. No evidence can be adduced in favour of either of these sup- positions that is satisfactory enough to prove it, and we have little other guide at present than a priori probability. In regard to the last of the three suppositions, however, it may be remarked that all analogy opposes the idea that the true olfactory apparatus should be thus scattered amongst the several segments of the body ; and the experiments which appear to favour it really lead to no other conclusion than this, that acrid or irritating vapours, taken in through the breathing-pores, may excite reflex movements which seem destined to expel them, or to withdraw the body from them. Such movements resemble those of coughing and sneezing in man, which are ex- cited through the nerves of common sensa- tion, and not through the first pair ; and they do not in the least indicate, therefore, that the sense of smell is in any way connected with the respiratory apparatus of insects, myriapods, &c. The use which many insects may be seen to make of their palpi, in taking cognizance of their food without actually touching it, suggests the idea that they are the true olfactive organs; and this idea is borne out by the fact, that these organs ter- minate, in the living state of many insects, in soft bulbous expansions, which shrivel up and become horny in the dead specimen, thereby obscuring their real character. On the other hand, many insects are furnished with soft membranous appendages at the base of their antennae, which seem equally adapted to perform this function. And it is asserted by Duges*, that insects whose antennae had been It cut oil' did not manifest the same cognizance of the neighbourhood of odorous substances, as did others of their kind whose antennae had been left entire. It would seem not a very improbable supposition that, as the antennas j and palpi are organs of a similar class, the sense of smell may not be localised in one or other of them constantly ; but that it may be assigned to one or the other, according to the j modifications they may respectively require for the performance of their other offices. The same doubt exists in regard to the olfac- tive organ of the Crustacea. The manner in which crabs and lobsters are attracted by odorous bait placed in closed traps, makes it almost certain that they must possess some sense of smell ; and the most probable locality of the organ would seem to be a cavity dis- covered by Rosenthal at the base of the first pair of antennae. As to the existence or absence of the sense of smell in the lower Invertebrata, nothing can be definitely stated. Nerve of smell. — That the first pair of cra- nial nerves is the true olfactive, and that through it alone are the proper odorous emanations perceived, would seem a legitimate inference from the fact, that its development in vertebrated animals is constantly propor- tionate, ccEteris paribus, to the acuteness of the sense ; and that it is chiefly distributed to that part of the nasal cavity, which is most distinguished by the possession of this endow- ment. This inference is fully borne out by the facts supplied by experiment and patho- logical observation. The division of the olfac- tory nerves in animals evidendy produces a complete destruction of the power of per- ceiving odours ; although they are st.ll affected * Physiologic Compavee, tom. i. pp. 160, 161. SMELL. by irritating vapours. They do not imme- diately perceive these vapours, however, but seem indifferent to them at first, and then suddenly and vehemently avoid them as soon as the Schneiderian membrane becomes irri- tated. It was maintained by Magendie that the fifth pair in some way furnishes conditions requisite for the enjoyment of the sense of smell ; this sense being destroyed, according to his assertion, by section of its trunk. His experiments, however, were made with irritating vapours which excite sternutation ; and he inferred the loss of the sense of smell from the absence of the automatic movements which these vapours normally excite. This in- ference was altogether unjustifiable ; since the experiments in question afford no proof that the power of perceiving odours, with which the excitement of automatic movements does not appear to be in any way connected, is de- stroyed by section of the fifth pair. A dimi- nution in the acuteness of the true sense of smell, however, appears to be a usual result of paralysis of the fifth pair ; but this is readily accounted for by the diminution of the nor- mal secretion of the pituitary membrane, by which its surface is deprived of the moisture that is necessary for the exercise of its sen- sory powers. The difference in the endow- ments of the first and fifth pairs of nerves, and the speciality of the former, are further marked by the result of mechanical irritation of their trunks and branches. Such irritation of the first pair excites no muscular movement, either direct or reflex, and it produces no in- dication of pain. On the other hand, irrita- tion of the nasal branches of the fifth pair is obviously attended with violent pain, and excites various automatic muscular move- ments. Lastly, it has been found that in cases of deficiency or loss of the sense of smell, some abnormal condition of the olfac- tive nerves or ganglia has existed ; and the same kind of change has been discovered in cases in which subjective sensations (i. e. sen- sations not originating in external objects) had existed during life. Conditions of the exercise of the sense. — The first condition requisite for the exercise of the sense of smell, is the contact of the odorife- rous medium with the olfactive surface. This may be favoured or prevented by a variety of circumstances. Thus, odours are more rapidly transmitted by air in motion than by air at rest ; but they only proceed in the direction of the movement : and hence animals pos- sessed of the keenest scent, which would be alarmed by the presence of a human or other foe a mile off on the windward side, may be approached within a short distance on the leeward, when afresh breeze is stirring. The odoriferous medium must not only be brought to the nose, but it must be introduced within the olfactive cavity. This is usually accom- plished by the ordinary movement of inspira- tion, which draws a current of air through the nose ; but as the current chiefly passes through the lower part of the nasal cavity, to which the olfactive nerve is very sparingly or not at 701 all distributed, the full use of the sense of smell is not thus gained. It is only by making a series of short and quick inspira- tions,— the effect of which seems to be, to empty the whole nasal cavity of the air it pre- viously contained, and thus to cause the newly-inspired air to pass forcibly into its upper part, instead of merely streaming through the passage between the anterior and posterior nares, — that we employ our olfactive powers to the best advantage. This move- ment, combined with the direction of the nostrils towards the source of the odour, and with the dilatation of their orifices by the muscles adapted for that purpose, constitutes the active exercise of the sense, which may he termed scenting. This bears the same rela- tion to ordinary smelling, as feeling bears to touch, listening to hearing, or looking to see- ing. The effect of the sensory impression on the mind is further heightened by the atten- tion which is bestowed upon it ; and it does not seem improbable that the sensation itself is rendered more acute by an increased deter- mination of blood to the olfactive surface when it is being thus actively employed. On the other hand, the use of this sense may be prevented, not merely by the closure of the nares, anterior and posterior, so as completely to exclude the odoriferous medium, but also by simply refraining from drawing air into the nasal cavity. If we breathe through the mouth only, closing the posterior nares by means of the velum palati, we may avoid being affected by odours even of the strongest and most disagreeable kind ; for the nasal cavity being already filled with air, there is no room for the entrance of the odoriferous atmosphere from without ; and it may thus be long before the odorous particles come into contact with the olfactive surface. It is, of course, an essential condition of the exercise of this sense, that the whole nervous apparatus, which forms the essential part of its organ, should be in a state of integrity ; and that a free circulation of blood shall take place through the olfactive portion of the pituitary membrane. But. in addition, it is requisite that the epithelial and mucous covering of the membrane be in a normal state. If the surface be too dry, the odorous particles cannot undergo that solution in the fluid in contact with the sentient extremities of the nerves, which seems necessary for the production of an impression on them. On the other hand, when the secretion is too abundant, it interferes with its contact in the opposite manner. And thus it happens that the sense of smell is blunted, both in the primary and secondary stages of an ordinary cold, by the disorder of the secreting surface, indepen- dently of the effect which the disturbance of the circulation may have upon the functional power of the olfactive nerve. Purposes of the sense. — When we take a comprehensive survey cf the animal kingdom, we at once perceive that the most general, and therefore the most essential purpose of the sense of smell, is to make known the pre- 702 SMELL. sence of food, to indicate its direction and thus to guide the animal towards it, and to aid in the discrimination of its qualities. We always find the olfactive organ placed in the neighbourhood of the mouth ; its connection with the respiratory apparatus is by no means so constant. In air-breathing vertebrata, whose olfactive cavity opens into the pharynx, the sense of smell largely participates in that of taste (see Taste), being the means by which we take cognisance of the flavours of sapid bodies introduced into the mouth. Of the importance of this sense in directing ani- mals to their food, it is needless to multiply instances ; but we may remark that, from ob- servation of the actions of the human infant, we are well convinced that it is rendered cognisant by smell of the neighbourhood of its nurse, long before it recognises her by sight, and that this sense is its guide in seek- ing the source of its nutriment. How purely instinctive this action is, — that is, how com- pletely independent of all experience, and en- tirely dependent upon the provocative sens- ation,— is well shown by the experiment of Galen, who placed a kid, just dropped, near three vessels, one filled with milk, another with honey, and another with wine ; after smelling at all three, it presently began to drink the milk. It would seem to be by the information conveyed through their smell, that bees are induced to fly to pastures at a great distance from their hive ; and it would not seem improbable that the sense of direc- tion, which is so remarkably displayed by many animals, is the result of the acuteness of their olfactive power. Whilst the chief use of smell to the carnivorous tribes is to guide them to their prey, the herbivorous races, whose food is constantly within their reach, are warned by its means of the neighbourhood of their enemies. The sense of smell is sub- servient to defence in another way; being the means by which the foetid scents, emitted by many animals under the influence of alarm, deter their enemies from further pursuit. In nearly all animals, the sexual secretions are more or less odorous ; and these would seem to be intended, not merely to contribute to make the sexes aware of each other’s prox- imity, through the sense of smell, but also, in many instances, to serve as a provocative to sexual desire. The odours which are attrac- tive to animals are usually related either to their food or their sexual instinct ; but there are cases in which animals seem to delight in odours which have no such relation : thus, cats seem to revel, as it were, in the odour of Nepeta (catmint) or Valerian. In the air-breathing vertebrata, the sense of smell is, as it were, the sentinel of the respi- ratory organs, having for its office to take cognisance of the aeriform fluids which enter them, and to give warning of such as are in- jurious. The contact of irritating matters, however, is perceived (as already stated ) through the general sense of feeling, not the special sense of smelling; and it is through the fifth pair that the act of sneezing is ex- cited, the purpose of which is to expel such I particles from the nasal cavity. The distinc- tion is well seen in some air-breathing inverte- brata, whose organ of smell is seated in the head, whilst the impression of irritants on the respiratory surface, exciting reflex movements for the purpose of avoiding or expelling them, is made through the stigmata. Thus M. Duges relates* that if the stigmata on one side of a decapitated Scolopendra be exposed to an irritating vapour, the body will be imme- diately flexed in the opposite direction ; and that if the stigmata on the opposite side be then similarly irritated, a contrary movement will occur ; whilst by exposing the anterior stigmata on one side, and the posterior on tire other, to the same irritation, the body will be bent into the form of the letter S. In man, the sense of smell is not ordinarily so acute as it is in many of the lower animals ; yet it is very possible that it may be capable jj of taking cognisance of a greater variety of odours. In the selection of his food, it is to him by no means the infallible guide that it seems to be in many other races ; for it not only gives no warning, in many instances, of what is noxious, but renders certain poisonous substances (as, for instance, those charged with prussic acid or the essential oil of al- monds) positively attractive. So, again, in regard to the respiratory organs, whilst it ij gives warning of the presence of certain gases and emanations which are injurious, it takes no cognisance of many others which are not less hurtful. In the ordinary conditions of civilised life, man is not dependent upon bis sense of smell for many of the ends which it jj answers in other animals ; hence this sense is j| altogether subordinate to others, and the want of it is not usually attended with any great inconvenience. But the case is far different among savage tribes, to whom it is as impor- j tant as it is to other animals in a state of nature, and in whom it seems to acquire, by the constant habit of attention to its indica- tions, a similar acuteness. Thus, it is stated by Humboldt that the Peruvian Indian, in the middle of the night, is informed of the proximity of another individual by his smell, and can distinguish by his sme'l whether the stranger be an European, an American Indian, or a Negro. It has even been asserted that some other savage tribes of mankind are enabled to follow a track by the scent of the footsteps, like the bloodhound. The sense of smell, moreover, usually acquires great acute- ness, when, from deficiency of the other senses, jj its indications become the chief or only means of recognising bodies not in immediate con- tact with the individual. Thus, in the well- known case of James Mitchell, who was deaf, , blind, and dumb from his birth, it was the principal means by which he distinguished persons, and enabled him at once to perceive the entrance of a stranger. Mr. Wardrop gives the following curious account of the mode in which he exercised this sense, and ol Op. cit. tom. i. p. 102. SMELL. the information which he derived from it : — “ There were some people whom he never permitted to approach him, whilst others at once excited his interest and attention. The opinions which he formed of individuals, and the means he employed to study their charac- ter, were extremely interesting. In doing this, he appeared to be chiefly influenced by the impressions communicated to him by his sense of smell. When a stranger approached him, he eagerly began to touch some part of his body, commonly taking hold of the arm, which he held near his nose, and after two or three strong inspirations through the nostrils, he appeared to form a decided opinion regard- ing him. If this was favourable, he showed a disposition to become more intimate, ex- amined more minutely his dress, and ex- pressed by his countenance more or less satis- faction ; but if it happened to be unfavourable, he suddenly went off' to a distance with ex- pressions of carelessness or disgust. When he was first brought to my house to have his eyes examined, he both touched and smelled several parts of my body ; and the following day, whenever he found me near him, he grasped my arm, then smelled it, and imme- diately recognised me, which he signified to his father by touching his eyelids with the fingers of both hands, and imitating the ex- amination of his eyes which I had formerly made.” We learn from the same account, that in selecting his food, he was always guided by his sense of smell, for he never took any thing into his mouth without previously smelling it carefully. He always recognised his own clothes by their smell, and refused to wear those which belonged to others. Sometimes the peculiar acuteness of this sense is restricted to a particular odour or class of odours, these usually proceeding from objects for which there is either a special fondness or a particular aversion. Thus, a gentleman blind from birth, who had an unac- countable antipathy to cats, so that he could never endure the presence of one in his apart- ment, one day, when in company, suddenly leaped up and exclaimed that a cat was in the room, begging his friends to remove it. It was in vain that, after careful inspection, they as- sured him that he was under an illusion. He persisted in his assertion, and his agitation con- tinued ; and on the door of a small closet being opened, it was found that a cat had been accidentally shut up in it. With such unequivocal proofs of the acute- ness of the sense of smell which may exist in the human subject, the statements made re- specting the extraordinary exaltation of the faculty in various forms of somnambulism be- come less incredible ; and the author is fully satisfied, from his own observations upon in- dividuals hypnotised by Mr. Braid (see Sleep ), that this exaltation may certainly take place in regard to the sense of smell. In one in- stance, a glove being placed in the hand of the hypnotised subject, he found out the owner of it without difficulty, from amongst more than sixty persons, scenting at each of 703 them, one after another, until he came to the right individual. And in another case, the owner of a ring was in like manner unhesi- tatingly found out from amongst a company of twelve. The information conveyed by the sense of smell is restricted to the quality and intensity of the odour, and to some general notion of its direction. This last, indeed, is rather de- rived from a comparison of its relative inten- sity when the face is turned towards different sides, than from any more direct information as to locality furnished by the organ itself. The absence of any consciousness of the part of the olfactory surface specially affected by the impression, — so that, unless the experiment be made, we know not that we are constantly exerting the sense on both sides, the double sensation being perceived as a single one, — is attributed by Messrs. Todd and Bowman *, with much probability, to the peculiar plexiform arrangement of the fibres of the olfactive nerve, and to the want of the isolation usually effected between the fibres by the white sub- stance of Schwann. Various classifications of odours, founded upon the impressions which they make upon the sense of smell, have been proposed ; but they are all liable to the objection, that there seems to be more of individual diversity in regard to the character of olfactory impres- sions, than with respect to those of any other kind. Many odours, by some persons thought intolerable, are very agreeable to others ; thus, assafoetida is known amongst some by the name of “ devil’s dung,” whilst by others it is spoken of as “food for the gods.” It was commonly employed by the ancients as a con- diment; but the individuals who thus relish it in our own country certainly constitute the exceptions to the mass. So, again, the fumet of game, so highly valued by the epicure, is disagreeable to most persons who have not been trained to appreciate it. On the other hand, the aroma of certain flowers, which is peculiarly agreeable to most persons, is by no means so, or perhaps the reverse, to others. Thus, Miiller remarks that the smell of mig- nonette is to him only herb-like; whilst the flower of Iris Persica has been pronounced to be of pleasant odour by forty-one out of fifty- four persons, by four to have little scent, by eight to be without all odour, and by one to be ill-scented.-)- It more frequently- happens, in regard to odours and savours, than with respect to other sensory impressions, that habit renders that agreeable, and even strongly relished, which was at first highly repugnant. ( (V. B. Carpenter .) SOFTENING and INDURATION (Ra- mollissement et Induration, — Endurcissement, Fr., die Erweichuvg und Hartung, Germ.) are terms used to express a pathological or phy- siological diminution and increase, of the con- sistence of the body or its parts. * Op. cit., p. 12. f Arnold’s Physiology, vol ii. p. 561. 704 SOFTENING AND INDURATION. Softening and induration in a physiological sense, refer to those changes which occur in the density of tissues and organs during their development, growth, and decay ; whilst, in a pathological sense, they refer to alterations in the normal consistence, with or without actual molecular change. In order to be able to distinguish morbid alterations of cohesion, from those which oc- cur in the natural course of things, it is neces- sary to be well acquainted with the power exercised by age, sex, and idiosyncrasy, in modifying the density of the tissues. Softening and induration are but relative terms, the standard of consistence is con- stantly varying, both as regards the whole body, or as regards organs and tissues. In the foetal state all the tissues are soft, and contain large quantities of fluid ; as develop- ment proceeds, so do the parts gradually be- come hard, not all equally so, for certain tissues remain permanently soft in comparison to others, which rapidly increase in density. After birth, the hardening processes still con- tinue, and it is not until the age of puberty is passed, that all the tissues have attained their highest stage of development. But the pro- cess of natural hardening is interfered with, or retarded, by peculiar idiosyncrasy and by the influence of sex and occupation ; the general firmness of the tissue of an athlete is greater than that of those, who, although in perfect health, happen to lead inactive and sedentary lives ; it is greater as a general rule in the male than in the female sex, and in the sanguineous than in the lymphatic temper- ament. As old age comes on, changes in the con- sistence of the tissues occur, which are pro- duced by the natural decay to which all organized matter is subject ; thus the cellular tissue, the serous and mucous membranes, the muscles and tendons, bone, the brain and nervous system, and particularly the uterus and ovaries, sometimes acquire a de- gree of hardness, equal to that which is known to be produced by certain diseases. Finally, after death the whole organism is affected by forces, which had little or no in- fluence upon it during life ; the tissues are subjected to the macerating influence of their fluids, which may also act chemically upon them. In the natural course of things, soften- ing and putrefaction, and disorganization of the ultimate atoms of our body occur, before they are fitted to be assimilated into other organized structures ; this decay increases as time progresses, and is enhanced by a high state of temperature and exposure to the air. After death, hypostatic congestion of the cel- lular tissue simulates the appearance that this structure frequently presents, when af- fected with inflammatory softening ; and the macerating effects of the fluids, which had no such influence during life, are seen in the brain and spinal cord ; w hilst the alimentary mucous membrane suffers softening and dis- integration from the peculiarities of the fluid usually secreted by it. By recognising then the normal alterations of cohesion, and those arising from post mortem causes, the attributes of morbid softenings will become perfectly fl apparent. Softening and induration are said to exist without any structural change ; such is not generally the case, indeed it is exceptional, and were such a state only to be properly termed softening and induration, many of the most important and interesting pathological facts would be unaccounted for. Softening and induration are produced by a variety of causes, |j and frequently co-exist in the same organ, Cl- one may supervene on, or cause, the other. Both softening and induration may be pro- duced by inflammation leading, on the one hand, to effusion of serum and pus, and on the other to the deposition and subsequent contraction and hardening of coagulable lymph ; the one appears to be the result of acute, and the other of subacute, inflam- matory action. Active sanguineous conges- tion produces in some organs the sensation of diminished consistence, whilst in others, especially in those surrounded by a dense fibrous tissue as the testicle, hardening results. In softening, the effused product of inflamma- i1 tion, appears not only to break down the structure by infiltration, but also by its pres- sure to impede the usual nutrition of the part. * The softening of an organ, induced by in- flammatory action, is frequently confined to one of the component tissues, especially to the cellular tissue ; the readiness with which the serous envelope may be stripped from off a parenchymatous organ, depends more upon the subserous cellular tissue, than upon the other structures; and, in like manner, the softness of a whole organ is often assignable,!! rather to the deficient tenacity of the mem- brane which unites its lobules, than of the proper tissue. Softening may be produced by causes totally !1 differing from those produced by inflammation ; it may depend upon a deficiency or perverted state of the blood, and an anaemic state of the general system. For instance, in white- softening of the brain, the arteries, which ought to have sufficiently nourished the af- fected parts, fail to do so on account of their being blocked up, more or less, by abnormal deposits. In certain softened states of the spleen, the blood contained in its parenchyma loses its consistence, and becomes more fluid than natural, from a perverted state of its constitution ; and the flabby muscles and general loss of tone of anaemic subjects are notorious. In scrofula, the perverted state of the gene- ral nutrition produces softening of peculiar tissues, for instance, of the bones ; and in the cancerous cachexia like effects occur. Long continued functional inactivity, for in- stance of the muscles of an extremity stricken with paralysis, tends to produce softening ; and pressure, in certain instances so interferes with the nutrition of a part as to diminish its cohesion. Fatty deposit in the ultimate cells SOFTENING AND INDURATION. 705 of tissues and organs, renders them soft and flabby; as will also infiltrations of certain morbid adventitious products. The coin- pound granule cells found in acute softening of the brain, and mixed with pus in other situations, are described in the article on Ad- ventitious Products. Softening may be accompanied by atrophy, or by hypertrophy, which is generally produced by simple conges- tion ; or no alteration of bulk may occur. Three degrees of softening are recognised ; — in the first, the softened tissue is still solid, but it breaks down and tears and can be per- forated with ease ; in the second, all solidity is gone, nothing but a pultaceous semi-fluid mass is found ; and, in the third degree, the tissue is broken down and diffluent. Softened parts may retain their natural colour, or may be paler, or may have an in- crease of colour. Softening, without any change of tint, occurs in mucous and serous membranes, in the brain, heart, liver, and uterus. All post mortem softenings are of this kind, except where the colouring matter of the blood has tinted the effused fluids. In certain softenings of the brain the af- fected parts are much paler than usual, being of a dead white colour ; there is a diminution in the quantity of blood usually present in the diseased parts ; a like decrease of colour is found in other softenings. Generally, however, softening is accom- panied by reddening, or by an increased co- lour ; the tints may vary from a bright ver- milion to a brownish red, and may be seen as grey, almost black, and, occasionally, are yellow. These varieties of colour depend upon the amount of blood usually existing in the softened tissue, and upon the degree of congestion. The redness of softened tissues is occasionally partial, and merges into lighter tints as the tissue becomes harder. Partial effusions of blood, or highly injected vessels, are commonly found in red softenings. Induration, generally speaking, is to be re- garded as a symptom of previous or coexist- ing diseased states ; its physical condition varies muclj in its nature, in the same or in different tissues, as proved by microscopical, mechanical, and chemical analysis ; and both observation and experiment tend to prove, that it is produced by causes of a very oppo- site kind. Changes in the amount of fluid destined for the nutrition of a part, frequently give rise to induration ; an increased quantity of blood and a consequent increased deposit of solid structure, produce simple induration of many organs, which are liable to variations in the quantity of blood they may contain, for in- stance, the brain and spinal marrow, the cellular and muscular tissues ; also of denser structures, as bone, in which the induration jis occasionally extreme, and in fibrous tissues ; they produce also hardening of the lymphatic glands and of the salivary glands. The brain las been found to be increased to twice its natural density and consistence. Muscular, ibrous, and cellular tissues, become so hard, VOL. iv. as to give out a grating sound when cut ; and the walls of some hollow organs, naturally soft and flaccid, acquire such a degree of firm- ness, that they preserve, when empty, a glo- bular or cylindrical form, and spring up with considerable force after sudden pressure ; and parts of bone acquire that degree of hard- ness, which has been termed eburneoid indu- ration. An increased quantity of the usual fluids of nutrition frequently gives rise to in- duration, differing from that just described, in not being attended by deposition of solids. The accumulation of blood in the vessels of the lungs and spleen, the result of congestion, produces, sometimes, a great degree of hard- ness and density of these organs. Diminution of the quantity of the same fluid, especially when there is also a compressing force, is also followed by an increase of consistence, and, generally, by a decrease in bulk of cer- tain organs ; in pleurisy, for instance, dense false membranes, by their pressure, compress the lung into a small space, and its tissue be- comes indurated from simple approximation ; for, on the removal of the compressing agents, the lung can be inflated. The inordinate increase and accumulation of the secretion of certain organs, as the mamma, testis, gall bladder, and kidney, pro- duce a degree of hardness, sometimes equal to that of dense tumors, arising from the in- compressibility of the fluids themselves, and the state of condensation of the walls of the organs in which they are accumulated. Effusions of serum and blood into the tissues from mechanical causes produce great distension and induration ; such is the case in the oedema of the cellular tissue of the extremities in dropsy ; effusion of serum into the intermuscular cellular tissue produces hardening. Pulmonary apoplexy and ecchy- mosis in various organs, from a mechanical impediment to the return of blood to the heart, have a like effect. But inflammation of a sub-acute form is the great cause of induration, from the effu- sion of serum and coagulable lymph ; the former of which is absorbed, and the latter becomes “ induration matter,” whose proper- ties are described under the head of Adventi- tious Products ; this last product produces induration on account of its being actually denser than the tissues into which it is effused, and, also, by its compressing power, for it has the peculiarity of contracting and becoming hard after its deposition. Certain morbid states of the blood, occasionally produce in- durations of certain organs. The changes of form, with which indura- tion may be connected, are numerous ; none may, however, occur ; the bulk also of in- durated structures varies ; it may remain un- changed, but, generally, it is increased, and more rarely, decreased. The colour of indurated parts, is generally different from the normal tint ; sometimes, owing to diminished vascularity, and to the presence of induration matter, it may be pale ; at others, owing to increased vascularity, and z z 70G SOFTENING AND INDURATION. the state of the fluids of the tissue, and the presence of effused or infiltrated matters, it may be bright or dark red, grey, yellow, and sometimes almost black. Induration presents several degrees of re- sistance to pressure or to the knife ; much depends on the ordinary cohesion of the af- fected organ. Generally speaking, the first degree is characterised by a slight increase in the resistance to pressure ; the second finds the tissue denser, cutting with a cracking noise ; and the third comprehends increased cohesion, amounting to a cartilaginous or bony hardness. Softening of the brain may be ascribed to inflammatory action, or to a defective state of the circulating apparatus of the organ ; it may be an effect of a defective or perverted state of the body generally, and it is frequently caused by post mortem agencies. Now these four varieties of softening, although, as re- gards their external appearances they have much in common, differ considerably from each other, each having peculiar attributes. The first and second varieties are generally found in the most, and the third in the least, vascular parts of the brain. Post mortem softening occurs, for the most part, in the immediate neighbourhood of the ventricles, is usually very diffused, is found on both sides at once, and is, of course, never preceded by symptoms. Softening of the brain may be partial or general, and may present various degrees : the least change of consistence is only to be recognised by the microscope ; in a more ad- vanced degree the softening is obvious to the unassisted senses, at first to the touch and then to the eye, the diseased part being pul- taceous, and readily removed by a stream of water, a cavity surrounded by healthy struc- ture being made evident. In a more advanced degree still, the cere- bral substance instead of being pultaceous is quite diffluent, and occasionally a perfect so- lution of continuity is found. The softened portion of brain presents various alterations of colour. In inflammatory softening, the colour mainly depends upon the previous quantity of blood in the part; it may be of a deep red colour, with or without effused clots of blood, and frequently merges at the edges into at first a deep, and then a pale, yellow colour. Sometimes the yellow colour is central and the reddened portion external, resembling a collection of pus, so much so that Lallemand described it as such. A dull red ocln-e colour with more or less hardening in the neighbouring structure, is indicative of chronic disease of long standing; as is also a chalky milk appearance, and a bright vermilion, of a recent effusion of blood into a previously softened part. In com- mencing softening, a diffused blush, with or without spots of blood, is generally found. A deep grey colour and fawn and dirty white tints accompany inflammatory softening, but much more frequently that which is produced by a deficient supply of blood. No alteration of colour takes place in post- mortem softening. These distinctions of colour indicate no essential differences, as far as structure is concerned, for all coloured softenings may present the same histological characters. As a general rule, the red varieties are indicative of acute inflammation, yellow of subacute, and white or grey of deficient nutrition of the affected part ; but this rule is by no means invariable. Universal softening of the brain, accom- panied by a smell of sulphuretted hydrogen, is; found in children suffering from general de- bility, and occasionally in infants stricken with induration of the subcutaneous cellular tissue.; Softening from a defective state of the cir-| culatory apparatus is found, for the most; part, in persons advanced in life, and consti-; tutes what is termed white softening. It de- pends on the presence of osseous, cartila- ginous, or atheromatous matter in the walls' of the arteries, nearly or quite blocking up their entire caliber, and affecting vessels o: all sizes. It may supervene upon occlusioi of the common carotid from ligature, and indeed, upon any circumstance retarding ol diminishing the quantity of blood to the brain l! intense inflammation may disorganise the ves: sels, carrying blood to a remote portion o the brain, and thus cause softening ; or ; severe blow, or the presence of a tumor oj greater or less density and magnitude, may act in the same manner. The very fact of adventitious product;! being found within the arteries, hints at ; perverted state of the brain and system genej rally ; absorption does not progress in tli diseased portions of the brain, which, bavin; lost their supply of blood, are in a state ana logous to that of an extremity attacked with gangrena senilis. The softening of the brain which is pro; duced by post mortem agencies is of ver,1 frequent occurrence. It may exist alone, o may complicate the other varieties, and i| caused by the decomposition natural to or« ganised bodies after death, or by the infif trating action of fluids, which, either durin life or in the agony of death, were effused int the ventricular cavities, and sub-arachnoi spaces. Softening of the spinal cord is of not tin common occurrence. It presents the same ehaj racters as those pertaining to the like affeq tion of the brain, is produced by the sam causes, and offers the same pathological cha racters. Softening of the whole cord ma occur, but most frequently parts of it onl are affected ; it is found softened most fre quently in the lumbar region, and not unfix quently in the cervical. Induration of the brain may be general c partial, and presents three degrees ofconsis; ence. In its first degree, the affected part nearly of the consistence of a brain whicj has been left some time in dilute nitric acid in the second degree, the indurated part is < a cheesy, and in the third of a waxy, fibre SOFTENING AND INDURATION. cartilaginous hardness. General induration affects either the whole or the greater part of the brain : the degree ofhardness never exceeds the first variety. The induration is not al- ways equal throughout the whole of the parts affected, the central medullary parts usually exhibiting a higher degree of it than the grey substance. A section of the indurated por- tions generally presents increased vascularit}', in the usual speckled and striated form ; yet the reverse is occasionally observed, the brain being preternaturally white. Induration of the spinal cord may be general 3r partial. Billard found a spinal cord in a child of a few days’ old, which, without the nembranes, supported a pound weight. In partial induration, the white, and not the grey, natter is usually affected. For further re- narks on the softening and induration of the ipinal cord, see the article Nervous Centres Abnormal Anatomy). Softening of the heart occurs as a diminished ;tate of the cohesion of the muscular structure, t is a rare disease, and is produced by very ipposite causes ; from inflammation, from a lefective state of the nutrition of the organ, vith or without general anaemia, and from a lerverted state of the nutrition of the mus- ular and cellular elements. The heart when oftened collapses on itself when empty, tears vith the greatest facility, and breaks down vith little pressure, the finger perforating its ubstance and penetrating into its cavities with reat ease. Its colour varies, being sometimes eep red and violet, at others dirty white, and ccasionally of a faint yellow hue. Soften- )g of the heart may be general or partial, uperficial or deep-seated ; it may be confined d the walls of a particular cavity, or to the entricular septum, or it may occur in small atches, disseminated in the midst of the mus- ular substance. Softening of the heart may oincide with hypertrophy of its walls, or a dated state of its cavities, and Hope found it ] a case of angina pectoris. When found as a sequel of carditis, the aftening is of a dark tint, the fibres are dark om the whole heart being gorged with venous lood, soft and loose in their texture, being asily separable, and compressed with facility etween the fingers. When accompanying ironic carditis and co-existing pericarditis, I lie white colour predominates, sometimes ling nearly superficial, and attended by peri- irdial and sub-pericardial effusion. The yellow-coloured softening is found in ises of local and general anaemia, in malig- mt fevers ; and it sometimes has an inflam- atory, as well as merely cachectic origin. An 'normal deposition of adipose tissue in the llular structure of the heart, produces sof- ning by affecting the nutrition of the mus- ;lar fibres, which suffer also from the state of stem peculiarised by the above deposition. Induration of the heart is said to follow rditis, and appears to be produced by the usion of lymph into the cellular tissue, uund the muscular fibres and beneath the mus membranes ; by its contraction and sub- 707 sequent hardening, it may pass into a sub- stance almost equal to bone in hardness. It may exist in any part of the organ, the whole of the apex and the column® carneae of the left ventricle were found indurated in one case, and in another the walls of the ven- tricles were tough, did not collapse, and emitted on being struck, a ringing hollow sound. We sometimes find partial softenings and indurations in the same heart. Softening of the lungs generally depends upon the presence of effused products of in- flammation ; for instance, in the engorged, he- patised, and suppurative stages of acute pneu- monia. It is w orthy of remark, that, although in the hepatised stage the lungs are heavier, contain less air, and appear denser, still they are more fragile, and on being pressed by the finger break down. The more acute and re- cent the inflammation, the greater the soften- ing. When we press a healthy lung with the finger, it gives to the touch on account of the elastic state of the tissue ; but this is lost, and an unusual resistance, easily broken through, is produced by the loss of air, and the pre- sence of lymph, compound granule cells, se- rum, and an abnormal quantity of blood. In the third stage of pneumonia, softening is produced by the alterations in the effused products ; lymph, for instance, is converted into a yellow friable matter, which subse- quently becomes pus. In typhoid pneumonia the softening is great, even in the first or con- gestive stage. Softening of the lung may be produced by an insufficient supply of blood. A part of a lobe may be so indurated, that the vessels and bronchial tubes passing through it become blocked up ; the tissue which ought to have been supplied by these becomes at first soft, and finally gangrenous. Induration may occur in any part of the lung, it may affect simply the bronchi and the tissue in their immediate neighbourhood, or the interlobular cellular tissue and the paren- chyma may suffer. The bronchi after long continued and re- peated attacks of inflammation are found in a more or less indurated state, the hardening being generally in the outer cellular coat, and the cartilages of the larger tubes may become as hard as bone. The lung in the vicinity is generally denser than it should be. The interlobular cellular tissue may be hardened at the same time as the lobules, or separately ; it becomes more apparent than usual, and acquires a density occasionally re- sembling fibro-cartilage, and sometimes exer- cises so compressing an influence on the lobules, as to obliterate them. But it is as a sequel of inflammatory action of long duration, that hardening of the whole or part of a lobe is found ; the vesicular struc- ture first suffers, the air vesicles are obliterated, and, often enough, the bronchi and blood- vessels of a certain magnitude. Such portions of lung are dense, not at all friable, possess a peculiar crispness, and con- tain little or no air. z z 2 708 SOFTENING AND INDURATION. The colour of an indurated lung may be light or dark grey, or brown, and rarely pale. A section of a piece of indurated lung shows the circular apertures of the bronchi and larger blood-vessels, surrounded by a dense tissue in which no vesicular structure is seen. The fibrinous dense lymph which produces these changes frequently becomes the nidus for tubercular deposit. Partial indurations are found around tuber- cular cavities and abscesses, and around collec- tions of miliary, or oflarger tubercular masses. In certain obstructive diseases of the heart the circulation in the lungs is so impeded, that effusion of blood, constituting pulmonary apoplexy, or effusion of lymph, producing general increase of density of the whole lung, may occur. Long continued pressure by a pleuritic effusion, has the effect of rendering the lung nearly solid and impervious to air. In treating of alterations in the cohesion of mucous , serous, and articular membranes, it is necessary to premise that they consist of a basement membrane sustaining epithelium cells and supported by sub-basement areolar tissue in which vessels, nerves, and absorb- ents, are found. The nutrition of the basement membrane and the proper development of the epithelium cells depend upon the amount and health of the fluid parts of the blood supplied to them by the capillaries of the sub-basement tissue. It is evident that any morbid state of this tissue will influence the integrity of the base- ment membrane and the epithelium cells ; and it is known that, for the most part, physical alterations of these last depend upon such morbid states, and that these changes are most likely to happen where the cellular structure is loose and considerable in amount. Softening has been found in all serous and fibro-serous membranes, and may be produced by inflammatory action and by a defective and perverted state of the general nutrition of the body. The lining membrane of the heart is fre- quently softened, being at the same time redder and more vascular than usual. It is occasionally so soft as to peel very readily from the muscular structure ; a like state of the pericardium exists with effusion of pus into its cavity. Softening of the internal membrane of the venous system is found of either a deep red or pale colour ; the tissue is very lacerable and breaks down into a pulp under the scalpel ; it may be caused by phle- bitis, by the pressure of a considerable column of blood, especially when the valves have been obliterated ; and is found in cases of malignant fever, scurvy, and whenever the fluids are greatly altered. Post mortem softening is frequent enough to raise our sus- picions, and great allowance must be made for the macerating and colouring properties of the blood. Chronic softening of the internal membrane of arteries is occasionally found ; when so affected the serous tissue is easily lacerable, and such solutions of continuity are deter- mined by causes, which ought in health to have no influence. Portions of the interior lining membrane may be found retracted and rolled up within the canal, so that with the effusion of lymph which generally occurs al the same time, and the consequent coagula tion of a small portion of blood, the artery may become completely obstructed and ob literated in a part of its course. Occaj sionally, the arteries of the upper and lowei extremities become thus affected in succes sion, on the employment of the slightes exertion, indicating a very extensive affectici of the nutrition of the arterial system. W> find, in cases of anaemia, and where athe roma is being deposited, considerable dinii nation of the general tenacity of the larg vessels. Softening of the arachnoid, peritoneim and pleura is generally found where there i effusion of pus, or blood into the sub-bast ment tissue ; it rarely occurs when lymph i thrown out into the serous cavity, but seem to be a more advanced phenomenon of ir flammation, or, rather, is produced by inflair, mation of a more intense and destructiv character. nino Dalmas ascribes nearly all serous softening to diseased states of the subserous cellula tissue, and we find constantly that on accouf of the altered state of this cellular structure the peritoneum and pleura may be strippe off large spaces of the parts they cover ; it notorious, that in the pelvis sero-sanguineoi effusion into the subserous cellular tissue, an| consequent lacerability of the serous men brane, frequently occur. Pulpy degeneratio, of synovial membrane is a kind of softenir with a perverted state of the nutrition of th tissue. Softening of mucous membranes is gem rally produced by inflammatory causes: it most frequently noticed, and is best studie in the alimentary canal, part or the whole < which may be affected ; it is most frequent observed at the end of the ilium, in the d< pending portion of the colon, and in the ca cum ; in the right and left hypochondriac r gions, and in the sigmoid flexure. Softening of the mucous membrane in g neral, or of any one or more of its elements | particular, presents various degrees. In tl first degree, the mucous membrane, instead ; possessing that degree of cohesion which pe mits of its being detached from the submucot tissue, breaks as soon as it is seized betwci the fingers or blades of the forceps ; in tl second degree, the edge of a scalpel, or t1 finger, pressed lightly over its surface, conver it into a soft and somewhat opaque crean looking pulp ; and, in the third stage, it is ; soft that it is removed with ease by a sligj stream of water. In this stage portions ot tl mucous membrane are found partially or e tirely destroyed, and having been removed the fluid contents of the stomach or inte, tines, as the case may be, during life, the su mucous cellular tissue is thus found destitu SOFTENING AND INDURATION. 709 ofits natural covering. It is in this manner that various forms of softening are produced, as irregular or circular patches of various sizes. It is important to notice this circumstance, for, when the softening is limited to thegland- ul® solitarias, as is frequently the case in dys- entery, it might be overlooked ; these bodies being very small, and their entire destruction by softening being often unaccompanied by any obvious alteration of the mucous mem- brane itself, the seat and nature of the intes- tinal affection might not be ascertained, were it not for the presence of a number of minute circular patches, which, when narrowly ex- amined, are found to be the result of softening bf these follicles ; for it often happens that enlarged follicles are seen intermixed with :he patches, and which, when a scalpel is tarried over the surface of the mucous mem- brane, break down or are removed, and thus ather patches are formed similar to the former. These circular patches, which have the sub- nucous tissue for their base, are often de- icribed as ulceration of the mucous membrane; tut in all cases of doubt, the scalpel, used as ibove, will enable us to determine their na- ure. Softening of the mucous membrane in the orm of stripes and bands, has been described vith great care by Louis, and has been much nsisted upon as a characteristic of inflam- natory softening; but Carswell has proved its >rigin from post mortem causes. Softening of the mucous membrane of the ligestive organs, may present various degrees if redness, or it may be quite pale; the red- ness may be confined to the softened part, or t may extend to the neighbouring parts at the ante time ; or the latter may be red and the ormer pale. The redness of the softened membrane may ary from a light or a dark red to a brown- ish or purple; varieties of colour the value if which it is by no means easy to estimate, aasmuch as the quantity of blood in an in- lamed tissue cannot be taken as a measure 'f the degree of inflammation which had aused the accumulation of this fluid. The pale softening presents also some va- iety of tint. The softened tissue is either of pale greyish or yellowish grey tint, being little ltered from its natural colour; or it may be aler than natural, when it generally presents milky aspect, owing to the colour of the ubmucous tissue being seen through it. The pale softening is found in pthisis, in ibercular disease of the mesenteric glands, nd in any disease accompanied by great ema- nation. Softening may be accompanied by thicken- ig of the submucous tissues, and may pre- ade and surround ulcerations. The inflammatory softening of the other mcous membranes resembles as closely as ossible that which has been described ; it is ot however so frequently complicated with iast mortem effects, nor does it so often occur, xcept in the oesophagus, stomach, and intes- nes from the action of irritant poisons, which produce it either by their direct action, or by inducing and modifying inflammation. Softening of mucous membranes from post mortem causes, is of great importance as a pathological fact, and may be produced by the action of the secretions of the membrane itself, or by putrefaction. This last cause is of doubtful efficacy ; it is not likely to be met with in post mortem examinations, made at a reasonable period after death ; it may however suffice to cause complete decompo- sition, when the membrane has been the seat of disease before death, and more particularly when the lesion has been of such a kind as to deprive the tissue of its vital properties sud- denly. General putrefaction rapidly occurs in many cases of sudden death, especially in those in which the nervous system, or blood, or both, happen to be the vehicles of the de- structive agent. Softening from the action of special secre- tions may occur in two manners, either by simple maceration, which is long in taking place, or by chemical action. The first may happen in all mucous membranes, the second in the stomach and intestines alone. Under favourable circumstances, and at a greater or less period after death, we find softening of the coats of the stomach, per- foration, and the contents of the viscus free in the cavity of the peritoneum. Various opinions have been given by the most celebrated pathologists, to account for this phenomenon; some embracing the views of Hunter, and recognising a chemical and post-mortem cause ; and others attributing it to certain inflammatory causes, which pro- duced ulceration and subsequent perforation. Now, Hunter’s view is demonstrable by direct experiment, whilst that held by the others is disproved by the absence of symp- toms during life sufficient to account for such vast organic changes, and by the difference between such ulceration and those solutions of continuity which we are now about to de- scribe. The following facts tend to strengthen the first, and militate strongly against the latter opinion. When a rabbit, dog, cat, or any animal, in fact, is killed an hour or so after a meal when digestion is going on, and is al- lowed to remain in one position and in a moderate temperature, we find, after a few hours have elapsed, that the mucous mem- brane of the most depending part of the stomach is softened, and can, with the sub- mucous cellular tissue and the muscular coat, be broken down with the greatest facility. The vessels ramifying in the softened part are black from the action of the solvent upon their blood. After a greater lapse of time we find the peritoneum perforated, and the contents of the stomach in its cavity ; by and by the tissues in the immediate neighbourhood of the stomach begin to suffer, and we see the ab- dominal muscles, and the cuticle covering them, eaten through by the gastric juice. In fish, softening and perforation occur so z z 3 710 SOFTENING AND INDURATION. rapidly, that, unless perfectly fresh specimens be used, no microscopic structure can be dis- tinguished in the stomachal mucous mem- brane. I have noticed the same thing to occur in caterpillars : their stomachs, which contain both globular and columnar cells, after a time become softened and are per- forated, so, subsequently, is the external cuticle ; nature seems to have taken this ori- ginal method of doing away with useless organisms. In ulceration of the stomach the affected part is generally circular, and if it reaches the peritoneum excites inflammation in the re- flexion contiguous to it ; by this means per- foration is rarely accomplished. Now, in post mortem perforations the softened part, said by some to be the seat of ulceration, is diffuse and the perforation large and irregular, and no part of the neighbouring peritoneum presents the slightest trace of recent inflam- mation ; shreds of muscular tissue and cellular membrane, moreover, form an irregular fringe around the opening, and, by their presence, detract greatly from the theory which calls such phenomena pathological and not pseudo- morbid. Generally speaking, the fundus is most fre- quently the part of the stomach most affected by the gastric juice ; but every thing depends upon its being the most depending part, and upon its containing more or less semi-digested food. The solvent matter is secreted by the tubes of the stomach, and consists of pepsin in com- bination with lactic acid and water : it pos- sesses the power of disintegrating all dead structures, but cannot influence the living tissues. It is not secreted when the stomach is empty, a stimulus to the mucous coat, in the form of some matter foreign to the stomach, is necessary for its production ; it is probably the case, that an ulcer of the mucous membrane may act as a stimulus, and that a certain quantity of juice may always be present in the stomach ; and that when, by the de- pressing effect of this lesion, the general nutri- tion suffers and the tissues are less able to resist decomposition, the gastric juice may act locally on the surface of the ulcer, and produce perforation before any peritoneal adhesion is formed. Perforation of the coats of the stomach sometimes occurs suddenly after a meal ; it is produced generally by the giving way of some small ulcer, the progress of which had been enhanced by the presence of a large quantity of corroding liquid. Post mortem softening may modify and ex- aggerate softening from other causes, and differs in its own appearances under various circumstances. The colour which the soft- ened membrane presents appears to depend upon the quantity of blood contained in the organ at the time of death ; if the quantity be small and natural, the softened parts are of a dull yellow or orange tint; and this colour increases with the quantity of the blood, and is accompanied by a black colour of the vessels. In infants and young children, and in anaemic patients and persons whose blood is deficient in quantity and altered in quality, containing | a great disproportion of serum, the whole stomach appears as if macerated ; it is, in- deed, sometimes infiltrated with serosity, and is so completely deprived of blood that no trace of this fluid is perceived except in some!] of the larger veins. Post mortem softening and perforation of the intestines may occur from the presence of an acid fluid, either within them or without,™ and derived from the stomach ; in the one case, softening is from within outwards, and, in the other, from without inwards. Softening of the skin : the skin may be sof- tened wholly, or one or more of its layers only.) In some skin diseases, especially among scrofu- lous subjects, there is an alteration of the cohesion of the epidermis, which is properly formed by layers of cells, the row nearest the i basement being smallest and more liquid than the others, the more distant being dry and united laterally, so as to form a dense integu- ment. Certain defects in the quantity and quality of the fluid contained in the newest made cells prevent them from progressing, normally, in their development ; they do no! become dry, neither is any disposition evinced by the basement to secrete other cells ; undci these circumstances the epidermis is soft, anc the basement tender and red, the tissue be- neath being visible. The cutis may lose its consistence in severa manners. When considerable quantities o serum are collected in the subcuticular eeliulai tissue, the cutis becomes mechanically dis tended and remarkably soft ; and sometime! is only represented by a thin friable tissue which breaks down with the least pressure It may gradually lose its fibrous structuro and degenerate into a tissue analogous to that usually found beneath it. Softening also occurs as a sequel of acub active local congestion. The appendages of the skin, the nails, hairs and, in the lower animals, horns, unaergfl softening to a certain extent in diseases c long standing, attended with great emaciations and softening of the cornea with ulceration i a common symptom of starvation. Induration of mucous membranes, is gene rally caused by long continued sub-acute it, flammatory action ; the sub-basement eeliulai tissue is generally affected, and thickening tj the whole structure, with hypertrophy of th papillae, where they exist, is found at th same time. Induration with hypertrophy | consequent upon chronic dysentery, and upo chronic inflammation of the bladder. IJlcei ation of mucous membrane is generally a| companied by surrounding thickening an] induration, and this last is frequent in thj gall-bladder, gall-ducts, uterus, and urethri Induration of mucous membranes is generallj accompanied by contraction of their caliber , >, It, parietal bones ; — m, n, n, 716 SOL1PEDA. process, which encroaches largely upon the squamous process of the temporal bone. The zygomatic process of the temporal (fig. 4*96. o) has at its base a process which projects upwards and backwards. This process con- stitutes the entire length of the temporal arch, articulating anteriorly by suture with the post-orbital process of the os fronds (Jig. 495. b, c), which is very long : the zygo- matic process of the temporal even extends to beneath the orbit, the bony circle around which it contributes to form, and is thence prolonged behind the os mala, so as to be- come articulated with the superior maxillary bone. The occipital suture is situated con- siderably in front of the superior occipital ridge ; nevertheless there is generally an in- terparietal bone of quadrangular shape, called by hippotomists the os quadratum, but which at an early age becomes consolidated with the two parietals. The interparietal is, indeed, itself frequently divided into two pieces in the new-born foal. It is always much too narrow to reach as far as the temporals. The anterior sphenoid appears but very slightly in the orbit. The posterior sphenoid mounts upwards in that region almost as high as the temporal, but without coming in con- tact with the parietal. Inferiorly, it is pro- longed in a square form considerably beyond the pterygoid region. The glenoid cavity for the articulation of the lower jaw is situated beneath the middle of the temporal arch ; it is convex inferiorly, and has a tubercle situ- ated behind its internal extremity, behind which, and on the same level, is situated the meatus auditorius externus. The bony meatus remains distinct from the temporal even when it has become completely consolidated with the tympanic and petrous portions of that bone. The tympanum is but little prominent, and of a very irregular shape. The petrous portion appears externally at the side of the occiput (Jig. 495. u), in front of the base of the para-mastoid apophysis (fig. 495.y>), which is here long and pointed. Of the bones of the face it may be ob- served, that the ascending apophyses of the intermaxillary bones (fig. 495. 15) are placed very obliquely, and become connected with the ossa nasi at about one third of the length of those bones from their anterior extremity. Inferiorly, their palatine apophyses penetrate between the maxillary bones as far as the first molar teeth, leaving two incisive foramina, or rather fissures, which are about half the length of the apophyses themselves. The pointed extremities of the ossa nasi arch over the cavity of the nose nearly as far as the middle of the intermaxillary bones. Supe- riorly, the ossa nasi increase in breadth as far as the inner angles of the orbits, where they become joined with the lacrymals (3, 4,5,6), which descend to a considerable dis- tance upon the cheek, and enter almost as largely into the structure of the orbital cavity. The jugal (fig. 495. 7, 8) advances upon the cheek as far forwards as the lacry- mal bone, and terminates beneath the middle of the orbit. This bone does not extend sufficiently far backwards to enter into the composition of the zygomatic arch, properly so called. It forms upon the side of the cheek, by its union with the maxillary bone, a broad, square ridge, which is continued backward as far as the commencement of the zygomatic arch. The palatine bone is deeply notched and very narrow, not extending forward beyond the penultimate molar tooth. This bone merely forms a narrow border around the meso-pterygoid fossa, but it composes more than two thirds of the pterygoid aim. In the floor of the orbit it mounts upwards, between the maxillary bone on one side, and the two sphenoids on the other, as far as the os frontis, but it does not come in contact with the lachrymal. The external pterygoid process of the sphenoid runs along the palatine externally, anti extends beyond it, but the internal pterygoid process is dis- tinct from the sphenoid, forming a long and narrow tongue-like process, which, after having covered the lateral suture of the an- terior end of the posterior sphenoid, extends obliquely over the centre of the pterygoid process of the palatine, anti proceeds to form a bony hook, situated upon the side of the great palatine fissure. Spinal column. — The cervical vertebra of the horse are, as in all mammiferous quadrupeds, seven in number; their proportions are mas- sive, and the whole series forms a chain of great strength and considerable flexibility. All the posterior vertebras of the neck have in the horse a square or oblong shape, and both the spinous and transverse processes are short and stunted, so as not to interfere with that freedom and extent of motion which is essen- tial in this portion of the spine. The atlas, as in man and other mammifera, presents characters peculiar to itself. The body of this bone is entirely suppressed, its place being supplied by the two articulating surfaces appropriated to the reception of the condyles of the occipital : the superior lamina are broad and flat, and the superior spinous apophysis is not developed ; w hilst, instead of transverse processes, the vertebra is prolonged laterally into two broad alas, into which nu- merous muscles are implanted. In the horse it may be remarked that the entrance of the canals for the passage of the vertebral arteries, instead of being situated at the posterior edge of the transverse apophyses, is placed upon its upper surface, but in other respects this bone presents no peculiarity worthy of special notice. Axis. — The configuration of the second cervical vertebra in most quadrupeds differs considerably from what is met with in the human subject, owing to the horizontal direc- tion of the neck, and the unfavourable posi- tion in which the head has to be sustained. This difference is most remarkable in the arrangement of the spinous process, which, instead of being merely a prominent tubercle, as in man, is prolonged into a vertical crest that SOLIPEDA. Fig. 497. 717 Skeleton of the Horse. ( After Stubbs.') Skull. — 9, orbit ; 11, 12, superior maxillary bone ; 12, infra-orbital foramen; 15, intermaxillary; 16, os nasi; 17,18, 19, lower jaw; 18, mental foramen; 19, coronoid process. Cervical region. — a, c, the atlas ; g, h, k, the vertebra dentata ; o, body ; r, transverse ; s, t, oblique, and u, spinous processes of cervical vertebrae ; z, process from the root of the transverse process of the sixth cervical vertebrae, assisting with its fellow to form the groove in which the longus colli muscle is lodged. Dorsal region. — c, oblique, and e, e, spinous processes of the two anterior dorsal vertebrae ; 5 to 18, continuation of dorsal spinous processes. Lumbar region. — a , b, c, d, e, f lumbar vertebrae ; l, the sacrum ; p, superior, and r, inferior, caudal vertebrae. Sternal region. — a, b, c, osseous and cartilaginous pieces of the sternum with the cartilaginous attachments of the true ribs. Shoulder. — h, i, o, the scapula; b, g, k, the os humeri. sometimes advances forwards above the atlas and is prolonged posteriorly above the third, or even the fourth, cervical vertebra, thus af- fording an ample expansion for muscular at- tachments. In the Solipeds, this spinous crest (&) is but moderately developed, extending backwards so as to overlap the third vertebra to some extent ; but its anterior prolongation is wanting. The transverse apophyses are short, and perforated by the vertebral canal, while the articular processes are but moder- ately developed, and directed backwards to articulate with those of the succeeding ver- tebra. The five posterior cervical vertebras are remarkable for their strength and mobility ; their bodies are of great proportionate size, and articulated together by broad sub-globular surfaces that allow a considerable extent of motion ; the vertebral laminae are broad and massive, and the articular processes well de- veloped and connected together by large articulating surfaces. The spinous processes are almost wanting except upon the sixth and seventh vertebrae, that belonging to the latter being of considerable size and turned backwards, so as to represent the commence- ment of the dorsal series of spines. The bodies of the sixth and seventh vertebrae of the neck, more particularly of the former, are prolonged infericrly into a central crest of considerable size, which projects downwards and backwards, and gives origin to the longus colli, which muscle is likewise lodged in a kind of groove formed by osseous plates derived from the transverse processes. The dorsal vertebree in the Solipeds are invariably eighteen in number, and are distin- guished by the shortness of their transverse apophyses, each of which is provided with an articulating surface, whereby it is connected with the corresponding rib as well as by similar articulations situated on each side upon the anterior and posterior extremities of their bodies to which the heads of the ribs are affixed. The spinous processes of the anterior dorsal vertebree are of great length, and dilated at their extremities, where they give origin to the broad elastic cervical liga- ment by means of which the weight of the 718 SOLIPED A. head is in a very material degree supported ; posteriorly, the spinous processes of the dor- sal region become gradually shorter, and their extremities broad and flattened, so as gradu- ally to approximate in their shape those of the lumbar region. The vertebra of the loins are, in the Soli- peda, usually six in number: such is the case in the horse, zebra, and quagga; but in the ass there are but five lumbar vertebras. This portion of the vertebral column is, in the class under consideration, possessed of great strength ; the bodies of the vertebrae are broad and firmly bound together ; the trans- verse processes of remarkable length and power ; the articulating apophyses strong and broadly connected with each other, while the spinous processes, which are of great breadth, are either quite straight or inclined forward. The sacrum in all the Solipeda is composed of five vertebrae consolidated into one piece, and, with that exception, scarcely different from the vertebral pieces that immediately precede and follow it. In the horse, as in most quadrupeds, the sacrum is much nar- rower in proportion than in the human sub- ject, and forming, moreover, a continuous straight line with the rest of the spinal column, allows of much more freedom of motion in this part of the skeleton than is possible in the human subject; and this is much increased by the obliquity of the junction between the sacrum and the iliac bones. The articulation, moreover, between the last lumbar vertebra and the sacrum, still further adds to the mobility of these parts ; for in the horse, the oblique processes of that vertebra are con- nected with the sacrum by means of articu- lating surfaces of very large size, so that from the combination of all these circumstances, there is a springiness given to this region of the vertebral column, the importance of which, in galloping or leaping, is at once conspicuous. The caudal vertebra; in the solipeds vary in number from seventeen to twenty-one ; but of these, the upper ones only resemble true vertebrae. Even in the first caudal vertebra, the inferior oblique processes become ob- literated, and as we descend, all the vertebral apophyses rapidly disappear : at the second bone of the tail, the spinal laminae no longer rise high enough to enclose the spinal canal ; but resemble two short processes ; and at about the fifth or sixth, ail vestiges of them are lost, nothing remaining but the bodies of the vertebrae of a cylindrical shape and slightly enlarged at each extremity, until we approach the last, where all regularity of form is lost. Thorax. — The sternum of the solipeds is considerably compressed towards its anterior extremity, which is moreover prolonged to some extent beyond the insertion of the first rib, so as to give to the whole chest a cari- nated appearance, which forcibly reminds the anatomist of the thorax of a bird. Posteriorly, the carinated form disappears, and the sternum becomes broad and flattened where it receives the cartilages of the posterior true ribs. The sternum of the horse is composed of several osseous pieces bound together by strong liga- mentous and cartilaginous connections. The ribs are eighteen in number, so that the thorax is prolonged very far backwards towards the pelvis. The anterior ribs are broad and massive ; but of these, eight only are attached to the sternum : the posterior or false ribs gradually become more slender as they recede backwards to expand over the cavity of the abdomen. Anterior extremity. — The frame-work of the shoulder in the Solipeda, as in all ungulate quadrupeds, is composed of the scapula only ; the coracoid apparatus being dubiously repre- sented by a rudimentary apophysis, and the clavicle is totally wanting in circumstances which allow of the close approximation of the shoulder blades to the sides of the chest, and thus cause the weight of the body to be trans- mitted perpendicularly to the ground. The shape of the scapula (fig- 498. o) is al- most that of an isosceles triangle, the spinal costa, which is about half the length of the other two, having its angles rounded off. The spine of the scapula is prominently deve- loped, and towards its upper third, projects posteriorly, so as to form a considerable re- curved process (i) ; as it approaches the neck of the bone, however, the scapular spine be- comes quite obliterated, spreading out upon the margin of the glenoid cavity (It), so that no acromion process exists in these quadru- peds. The humerus (fig. 498. c, b, Ic) is short, hut of great strength, and the muscular imprints strongly marked. Th e forearm is almost exclusively formed by the radius (fig. 498. o, r), the strength of which is in accordance with the enormous weight it has to sustain, while the ulna is reduced to a mere appendage (y?g.498.«, u), which in the adult animal is completely consolidated with its posterior surface, the line of demarcation between the two being only indicated by a fur- row which, towards the upper extremity of the forearm, deepens into a slight fissure. The olecranon process is, however, of large size, and, by its projection posteriorly, affords a powerful purchase to the massive extensor muscles inserted into this portion of the limb. From the above arrangement of the bones of the forearm, it is manifest that all movements of pronation and supination are here out of the question ; the limb must remain constantly fixed in a state of pronation, in which con- dition it is anchylosed, and thus acquires a firmness and steadiness which would be quite incompatible with more extensive movements. The carpus in the Solipeda consists of seven bones arranged in two rows, — of which four are situated in the first, and three in the second. The upper series consists of the representa- tive of the os scaphoides of the human subject ( fig. 498. w ) ; of the os lunare ( x ) ; of the cuneforme (y) ; and of the os pisiforme (z). In the lower series, the os trapezium, which supports the thumb of the human hand, does not exist in the horse ; but the trapezoid (not SOLIPEDA. 719 seen in the figure) the os magnum (2.) ; and the unciforme (3.) are all of them readily identified. Fig. 498. Osteology of the Horse — Hones of the anterior Extremity. Scapula. — h, its neck ; i, spine ; k, coracoid apo- physis ; I, l, inferior costa ; m, m, superior costa ; n, n, base; o, fossa subspinalis ; p, fossa supra-spinalis. Os humeri. — a, shaft of the bone ; h, protuberance into which the teres major is inserted ; e, bicipital protuberance ; f neck of the humerus ; i, external condyle ; K, double articular suface, articulated with the radius ; k, internal condyle ; l, anterior fossa which receives the upper head of the radius, when the fore- arm is bent ; m, posterior sinus, for the reception of the olecranon of the ulna, when the fore-arm is ex- tended. Radius. — n, its upper head ; o, protuberance for the insertion of the tendon of the biceps; r, its lower extremity. Ulna. — s, the olecranon process ; t, its articulation with the humerus ; ?«, continuation of the bone which in aged horses becomes united with the radius. Bones of the carpus. — w, Scaphoides ; .r, Lunare ; y, Cuneiforme ; z, Pisiforme or Orbiculare ; 2, Os magnum ; 3, Unciforme. Metacarpus. — 4, 5. The great metacarpal or cannon bone. G, 7. Rudimentary external metacar- pal bone. 10, 11. Sesamoid bones. Fore-foot. 12, 13. Pronhnal phalanx or great pastern bone. 14, 15. Middle phalanx or lesser pastern or coronary bone. 16. Terminal phalanx or coffin-bone. 17. Sesamoid bone. The metacarpal bones are in the horse con- solidated into one large piece, called by farriers the shank or cannon bone, and two smaller supplementary pieces, which seem merely ap- pendages to the former. The large cannon bone {Jig. 498. 4, 5.) is formed by the union of two metacarpal bones indissolubly conjoined, — viz. of those which support the ring and middle fingers in the human hand ; these conjoined, here form a massive piece, the upper end of which articu- lates with the carpus, while its distal ex- tremity sustains the first joint of the foot. A second or supplemental piece (/%.498. 6,7.) is simply a rudiment representing the internal metacarpal bone of the human skeleton, or that which in man supports the little finger ; superiorly this piece presents an articulating surface, which articulates with the unciform bone of the carpus, but interiorly, there being no finger for it to support, it gradually dwindles away to a mere splint, which is ap- plied against the ulnar aspect of the preceding bone. The third bone of the metacarpus is equally rudimentary as the last, and consists of a ■similar styliform bone applied against the op- posite side of the shank bone, and obviously representing the metacarpal bone of the fore finger. The fore foot of the horse is composed of three bones, representing the first, second, and third phalanges in the fingers of the human hand ; but extraordinarily changed in their appearance. Of these, the first {fg. 498. 12, 13) is equivalent to the bones of the first phalanges of the ring and middle fingers in the human subject, as is indicated by a central groove, showing this piece to be composed of two lateral halves — this bone in the horse is called the “great pastern .” The second piece {Jig, 498. 14. 15.) corre- sponding with the second phalanx, is named, in common language the'" little pastern,” while the third (16), the representative of the third phalanx, a bone of very large size and cres- centic shape, has received from farriers the name of the “ coffin bone.” In addition to the above may be noticed two sesamoid bones (10, 11) implanted in the flexor tendon of the foot, as it passes behind the articulation between the cannon bone and the great pastern, and a third lying over the posterior part of the articulation, between the coffin hone with the coronary bone, or be- tween the two distal phalanges. Posterior extremity. — The pelvis of the so- lipeds, both in its disposition and in the shape of the bones composing it, differs in many important particulars from that of man, and even of the generality of quadrupeds. The body of the ileum is elongated into a sort of 720 SOLIPEDA. neck, while its crest and spine, extending themselves outwards almost at a right angle with the body, give the whole bone a shape somewhat like that of the letter T, or of a hammer, of which the body of the bone will form the handle, while the extremity of one of its branches is articulated to the side of the sacrum, and the other forms a broad ex- pansion, the inner surface of which is turned obliquely towards the spinal column. The body of the ileum joins the ischium and pubis at a very obtuse angle, the cotyloid cavity being excavated in the usual manner in the line of junction between the three bones. Fig. 499. Ligaments of the anterior extremity of the Horse. a, a, Ligaments of the scapula ; b, capsular liga- ment of the shoulder-joint ; h, radial nerve ; li, cap- sule of elbow-joint; d, d, d, e, e, e, ligaments of the elbow, carpus, and phalanges ; o, outer cartilage of the hoof ; p, inner cartilage of the hoof. The os femoris in the Solipeda is very strong and massive, with well developed tro- chanters, and prominent ridges for the attach- ment of the muscles implanted into it : it is however so short as to be entirely concealed within the flesh and integuments of the trunk, so that what is ordinarily designated the thigh in these quadrupeds is in reality the muscular portion of the leg. Inferiorly the articulating surface that sustains the patella is no longer, as in the human subject, continuous with that of the knee-joint, but forms a distinct articu- lation upon which the patella (yfg.500. q) plays during the movements of the leg. Fig. BOO. Femur. — a, Body of the bone ; b, its neck ; e, the head incrusted with cartilage ; d, d, trochanter major, or “ spoke ” ; f, projection of the linea aspera, into which the glutseus extemus is inserted; 3_3 The canine teeth, however, it must be observed, only exist in the male sex. The incisor teeth, in the generality of her- bivorous quadrupeds, are bevelled off poste- riorly, so as to present in front chisel-like cutting edges ; but in the Solipeds, when young, the lateral incisors are furnished with two cutting edges, one in front and the other behind, from which circumstance those cen- tral fossae are produced which, as we shail see further on, furnish important testimony relative to the age of the animal. The canine teeth, here called “ tusks ,” or “ tushes ,” are always of very moderate dimen- sions, and their points, at an early age, become flattened and blunt. Those of the upper jaw are separated from the incisors by a con- SOLIPEDA. siderable interval ; and a similar interspace also exists, but to a less extent, in the lower jaw. The molar teeth of the horse are of a pris- matic form, their grinding surfaces being marked with four crescents of enamel in the lower jaw, and with five in the upper: these crescentic patches in the upper jaw have their concavities turned outwards, but in the lower jaw in the opposite direction. The teeth of the horse are, moreover, distinguishable from those of the ox and some other Ruminants, which they resemble in their general appear- ance, from the circumstance that, in the latter, the crescentic patches of enamel are arranged in pairs, and are placed parallel to each other ; whilst in the horse they are situated alter- nately, the first of the inner margin of the tooth corresponding to the interval between the two of the outer margin. Professor Owen * observes, that the cha- racter by which the horse’s molars may be best distinguished from the teeth of other Herbivora corresponding with them in size, is the great length of the tooth before it divides into fangs. This division, indeed, does not begin to take place until much of the crown has been worn away ; and thus, except in old horses, a considerable portion of the whole of the molar is implanted in the socket by an undivided base. The deciduous molars have shorter bodies, and sooner begin to develope roots ; but in these, or in an old permanent molar with roots, the pattern of the grinding surface, though it be a little changed by partial obliteration of the enamel folds, yet generally retains as much of its cha- racter as to serve, with the form of the tooth, to distinguish such tooth from the permanent molar of a Ruminant. A knowledge of the structure and history of the teeth of the horse becomes addition- ally important, from the circumstance that it is from the condition of the dental apparatus that an estimate may be formed concerning the age of the animal ; and, in order to un- derstand the data thus afforded, it will be necessary to consider the structure of these organs rather more closely. The incisors f, when the permanent teeth are first completely developed, are arranged close together, forming the arc of a circle at the extremity of both jaws ; they are slightly curved, with long simple sub-trihedral fangs, tapering to their extremity. The crowns are broad, thick, and short; the contour of the biting surface, before it is much worn, ap- proaching an ellipse. These teeth, if found detached, recent, or fossil, are distinguishable from those of the Ruminants by their greater curvature, and from those of all other animals by a fold of enamel, which penetrates the body of the crown from its broad flat summit, like the inverted finger of a glove. When the tooth begins to be worn, the fold forms an island of enamel, inclosing a cavity partly * Odontography, p. 574. •f Owen, Odontography, p. 572. 733 filled with cement, and partly by the dis- coloured substances of the food, and is called “ the marie’' In aged horses the incisors are worn down below the extent of the fold, and “the mark” disappears. The cavity is usu- Fig. 505. Lower jaw of a one-year-old Colt; milk incisors . ( After Youatt.). Fig. 506. Two-years' -old; milk incisors, middle pair much worn. ( After Youatt.') Fig. 507. Three years ; the tiro middle teeth have been shed and renewed; the canines just appearing above the gums. ( After Youatt.) SOLIPEDA. 734 F'g. 508. Four years ; four teeth have been shed and renewed. ( After Youatt.) Five years ; all the incisors have been shed and re- newed; the middle pair much worn. (After Youatt .) ally obliterated in the first, or mid-incisors, at the sixth year ; in the second incisors at the seventh year, and in the third, or outer incisors, in the eighth year, in the lower jaw. It remains longer in those of the upper jaw, and in both the place of the “ mark ” con- tinues for some years to be indicated by the dark-coloured cement, even to about sixteen years old. At this period the worn summits of the incisors present a subtriangular form. The canine teeth are small in the horse, and rudimentary in the mare ; the unworn crown is remarkable for the folding in of the anterior and posterior margins of enamel, which here includes an extremely thin layer of dentine. The representative of the first premolar in the first set of teeth is a very small and simple rudiment, and is soon shed. The three normal premolars are as large and complex as the true molars, the anterior one being usually the largest of the series in the upper jaw. Salivary Glands. — The salivary apparatus in the Solipeda is very extensive, perhaps more so than in any other class of quadrupeds, con- sisting of large glandular masses divided into numerous lobes and lobules of a pale colour, and but loosely connected together by cellular tissue. The Parotid Glands in the horse constitute a secreting apparatus, the bulk of which is extremely remarkable. Each of these glands extends from the external meatus auditoreus along the side of the head and of the lower jaw, as far forwards as the masseter muscle, and at the same time stretching deeply in- wards as far as the side of the trachea. This enormous glandular organ may be considered as composed of three principal portions : each furnishing its excretory duct, which, however, soon unite to form a common canal, which at first descends within the angle of the jaw, whence, winding round the anterior edge of the masseter, it mounts up externally as far as the buccinator muscle, which it perforates nearly opposite the fourth molar tooth of the upper jaw, its internal orifice being situated in the centre of a prominent papilla. The Submaxillary Glands are much smaller than the parotids. Posteriorly they consist of a thick globular portion, which is adherent to the inner surface of the parotid, but as they advance forwards, they become consider- ably attenuated, each terminating in its appro- priate duct. The latter is of considerable length, and, after passing the sublingual gland, with which it contracts some attachments, opens into the mouth at a little distance be- hind the canine tooth, its opening being in the immediate vicinity of a papilla that seems to form a kind of valve at its orifice. The Sublingual Glands are smaller than the preceding, and are of an oblong shape : they pour the saliva that they secrete into the cavity of the mouth through numerous orifices arranged in several rows on each side of the tongue. In addition to the above large glandular organs, there remain to be noticed the Molar Glands , consistingof numerous detached granu- lar-looking bodies of a lenticular shape situated beneath the mucous membrane that lines the buccinator muscle, and the inner surface of the superior maxillary bone behind which they mount up into the zygomatic fossa to within a little distance of the abductor muscle of the eye. Pharynx. — The pharynx in quadrupeds generally presents a structure very similar to that of the human race, and may be said to be composed of analogous muscles : nevertheless its horizontal position in these animals renders the necessity for muscular exertion during deglutition greater than in man ; and, accord- ingly, these fibres are not only stronger in quadrupeds than in our own persons, but sometimes additional muscles are met with, by the aid of which the action of swallowing is facilitated. In the horse, the muscle which represents the middle constrictor of the pharynx might more properly be called the pterygo-palato - SOLIPED A. 735 pliaryngeus*, its fibres descending from the pterygoid and palate bones, along the sides of the pharynx, around which they wind obliquely, uniting in the middle line upon its posterior surface, where they form a thick muscular layer. The inferior constrictor, or thyro-pliaryngeus, is equally broad and strong, its fleshy fibres taking nearly the same direction as they pro- ceed towards the back of the pharynx, where they join by a median raphe. In addition to the above, there is a crico- pharyngeus, arising from the posterior and inferior margin of the cricoid cartilage, whence its fibres extend obliquely upwards along the sides of the pharynx. The analogue of the stylo-pharyngeus is, in the Solipeds, a cylindrical muscle derived from the styloid bone, and, running from be- hind forwards upon the sides and upper part of the pharynx, mixes its fibres with those of the superior constrictor — its action is to raise the commencement of the pharyngeal sac, which it at the same time dilates and draws backward. There is likewise a small muscle derived from the middle part of the styloid bone, the fibres of which run backwards and inwards, so as to meet those of the muscle last men- tioned. Lastly, there are two other muscles, the fibres of which take a longitudinal direction. One of these, the pharyngeus proprius, arises from the tendinous middle line that extends from below the insertion of the stylo-pha- ryngei, and is prolonged downwards along the posterior and lateral walls of the oesophagus : the other, the aryteno-pharyngeus, is a small muscular band proceeding from the back part of each arytenoid cartilage, and running down the front of the oesophagus towards the sto- mach. Stomach. — In all the Solipeda the stomach is simple, and presents little remarkable in its shape. The oesophagus (Jig. 510. b) is in- serted at a very acute angle into its smaller cur- vature, which is, as it were, folded upon itself. The cardiac cul-de-sac (c) is very capacious. Fig 510. Stomach of the Horse. * Cuvier, Lemons cl’Anatomie Comparee, tom. iv. p. GOG. and is lined throughout internally with a thick cuticular layer continuous with the lining of the oesophagus, and extends nearly as far as the middle of the stomachal cavity, where it terminates abruptly by a prominent indented edge, the interior of the pyloric half of the viscus (a, cl) presenting the usual villous mu- cous surface. The muscular coat of the stomach consists of several superimposed layers of fibres that cross each other in differ- ent directions, some of them being apparently derivations from the muscular bands of the oesophagus ; and it is doubtless the contrac- tions of these muscular bands, in conjunction with the obliquity of the entrance of the oeso- phagus, that renders the act of vomiting im- possible in these animals. The alimentary canal in the Solipeds is short in comparison with that of the Rumi- nants and some other herbivorous quadru- peds ; but this want of length is perhaps more than made up for by the enormous capacity of the large intestine, which, on first opening the body of one of these animals, seems of itself to occupy the whole of the abdominal cavity^. Commencing from the pylorus, the duo- denum (Jig. 510./.) is found to be considerably Fig. 511. Caput Coli Sfc. of the Horse. dilated ; but its diameter soon contracts, and the rest of the tract of the small intestines is of pretty equable dimensions throughout, or if it presents constrictions here and there, they disappear when the gut is distended with air. The iliac portion of the small intestine (Jig. 51 1. cl) terminates in a caecum of enor- mous bulk (Jig. 511. <7, b, c, e,f ), which is separated from the commencement of the colon by a deep constriction (g) : the colon itself is throughout its entire extent propor- tionately voluminous, commencing in the right flank: its ample folds (Jig. 512. a, b) mount upwards as far as the diaphragm, whence they descend again, forming a viscus of vast capa- city as far as the left iliac region, where, be- coming gradually contracted in its dimensions, it terminates in the rectum. The ascending portion of the colon (a, b ) is separated from the descending part (e, d) by a constriction ; and the latter forms a third remarkable dila- tation before it ends in the rectum. The whole colon is puckered up into huge sacculi by three longitudinal muscular bands, which 736 SOLIPEDA. terminate where the rectum begins, the last- small size, in which, the faeces become moulded named division of the alimentary canal pre- into balls preparatory to their expulsion, renting only a few pouches of comparatively When in a state of moderate distension, the Fig. 512. Colon of the Mare in Situ. small intestines of an ordinary size are found to measure about fifty-six feet in length from the pylorus to the csecum, with a circumference varying according to the state of contraction of the bowel from two inches and a half to six inches. The caecum is about two feet and a half long, and about two feet in circumfer- ence at its broadest part ; but towards its blind termination it assumes a conical form, and terminates in a point (Jig. 511.6). Above the ileo-csecal junction, the intestine forms a cul-de-sac (Jig. 51l.e), which is bent upon itself so as almost to resemble a second caecum separated from the rest of the colon by a deep contraction, and there is, moreover, sometimes a third globular cavity, situated as shewn in Jig. 511 ■ f: but this is not constantly present. The enormous colon ( Jig . 512. a, b, c, cl), which seems of itself to occupy the whole abdominal cavity, is divided into two por- tions : — the first (a, b) is about 2 feet 3 inches long, and, at least, two feet in circumference ; the second portion ( c , d) is ofnearlvthe same dimensions; but towards its termination, its circumference diminishes to 10 inches, anti the continuation of the bowel retains that size for the length .of a couple of feet, when it again enlarges to a cir- cumference of 2 feet 4 inches before its ter- mination in the rectum. The entire length of the colon and rectum taken together is 2 l feet, which, added to the length of the small intestines, gives a total length of 77 feet for the intestinal canal, ex- clusive of the caecum. Liver. — T'his viscus in the horse is divided pretty equally between the left and the right sides of the body. It is divided into four lobes, measures about a foot and a half in its j greatest diameter, and weighs between four i and five pounds. There is no gall-bladder ; but the hepatic duct is extremely capacious, and evidently forms a receptacle for the biliary secretion. Spleen. — The spleen of the horse has the shape of an elongated triangle, situated, ob- SOLIPEDA. 737 liquely, upon the left side, of the stomach ; its base pointing upwards and backwards, and its apex downwards and forwards; it is about 9 inches long, 4 inches broad at its widest part, and three-quarters of an inch in thick- ness. Its weight is about twelve ounces. The pancreas is of an irregular shape, ap- pearing to be made up of three branches — the shortest of which terminates at the duodenum ; of the other two, one extends beneath the right, and the other reaches as far as the left kidney: these three branches form, by their union, a flattened mass, about half an inch in thickness, which may be called the body of the pancreas. There is nothing remarkable in the arrangement of its excretory duct. Circulatory Apparatus. — The struc- ture of the heart and the general arrangement of the arterial and venous systems offer no pecu- liarities worth}' of notice. Structure of the Horse’s Foot. — The mechanical structure of the foot of the horse demands to be considered at length, for in what- ever point of view this part of their economy is regarded, either as a simple instrument of progression, or a curious piece of anatomy, it will be found equally deserving the study of the physiologist and of the veterinarian. Nu- merous writers have accordingly devoted their attention to this subject, both on the conti- nent and in our own country ; but their de- scriptions are, unfortunately, so mixed up with terms of farriery and stable jargon, that the anatomist finds considerable difficulty in deciphering their elaborate disquisitions. Among the most philosophical English treatises are those of Professor Coleman and Mr. Bracy | Clark, to both of whom we shall be indebted for many of the following observations. Horny hoof. — The whole exterior conical covering of the horse’s foot, called in tech- nical language the “ wall of the hoof,” is formed of a dense horny substance, which in shape resembles a hollow cone obliquely truncated at its upper part, so that the hoof is deepest or highest in front of the foot, diminishing in this respect as it recedes back- wards towards the “ quarters ; ” it then loses, to a considerable extent, its conical shape, and becomes nearly upright, especially on the inside or inner quarter, still growing narrower or lower to the posterior extremity of the foot, where, at first sight, it appears to termi- nate by mixing with the substance of the “ frog,” hereafter to be described, and with the integuments of the posterior region of the foot : instead of terminating in this manner, however, a more accurate examination shows it to be suddenly inflected inwards, pursuing its course towards the centre of the foot, where, diminishing gradually in depth, it is finally lost, becoming mixed up with the “ sole,” near the point of the frog, thus form- ing a distinct and remarkable internal wall that supports the under parts of the foot, and at the same time protects, by its bold projection, the sole and the frog from an undue degree of pressure and contusion against the ground. The parts thus formed by a continuation of the wall of the hoof beneath the foot, are called the “ bars of the foot,” and are fre- quently described with, and taken for, part of the “ sole.” The direction of this sloping floor serves to throw all superincumbent pres- sure outwards towards the sides of the foot, and at the same time leaves a triangular space, posteriorly, for the insertion of the frog (fig. 513.), which it likewise protects from injury. Fig. 513. Structure of the hoof of the Horse. 1, the sole. ; 2, section of the horny hoof ; 3, upper surface of the frog ; 4, 4, the horny heels ; 5, Bars of the foot ; 6, walls of "the hoof ; 7, 8, 9, 10, 11, boun- daries of the vaulted space, £ in which the frog is lodged ; 12, 12, the sensitive foot. The wall thus constructed appears to form the basis of the mechanism of the hoof, to which all the other parts are subordinate, and, if so understood, will much facilitate our views of the nature and economy of its structure. Its inner surface is every where lined, as it were, with numerous elastic lamellae that pro- ject internally, and arranged in parallel lines, proceeding downwards perpendicularly to- wards the front of the foot (fg- 514, 3.) : these horny laminae are, at least, five hundred in number, and afford, from the aggregate surface that they present, a very extensive superficies for the attachment of an equal number of similar processes, derived from the vascular surface that covers the coffin bone, with which they interdigitate in such a way that the pres- sure to which the foot is subjected, which if concentrated upon a small surface would in- 3 B ! 738 SOLIPEDA. evitably cause the destruction of living tissues, becomes so diffused as to produce no incon- venient results. The horny lamellae above alluded to, when removed from the hoof, have little or no elasticity when drawn in a longitudinal di- rection; but when drawn transversely, they possess this quality in a very remarkable de- gree, more especially in resisting pressure ap- plied in a direction outwards and downwards, to resist which, the arrangement of their fibres is, on close examination, found to be particu- larly adapted. The whole horny hoof, if unravelled by maceration or long continued exposure, is found to be essentially composed of longitu- dinal corneous threads or hairs matted, and, as it were, strongly glued together, — a structure preeminently adapted to combine all the re- quirements of strength, elasticity, and tough- ness. As it approaches the quarters and heels, the horny helmet encasing the foot diminishes in its thickness as well as in height, affording, by this means, a degree of pliancy, which here becomes as necessary as firmness and unyield- ing solidity were in the front of the organ ; yet, even here, by the doubling in of the hoof towards the sole, a strong horny margin is left, which is admirably adapted to receive the principal bearing of this part of the foot, and to protect and defend the sole enclosed within its curvature. Frog. — The triangular chasm left by the inflections of the wall towards the centre of the foot, is filled up by a very remarkable organ, named, in the language of farriery, the “ frog,” either from some fancied gross resem- blance which it bears to that animal, or, more probably, by corruption, from the French “ fourche ” or “ fourchette,” Anglice “ fork,” applied to the same structure. By Latin writers, it is generally known under a similar appellation, “ furca,” and by the Greeks was named “ xeA‘<5ora,” from a similarity between its shape and that of a swallow. This bod}', which externally has the ap- pearance of a triangular mass of elastic horn, may not be inaptly compared to an elastic key-stone received into an elastic arch com- municating in some cases, and admitting in all, the springing movements of which such an arch would be capable. Its bar, which, to- wards the heels, is thin and broadly spread out, possesses a considerable degree of flexi- bility, which is gradually lost in approaching the centre of the foot, where there is less occasion for movement. The bnse of the frog lies between and con- nects together the two posterior incurvations of the hoof ; it then passes over and en. ve'opes those parts, restraining their action. The sides of the frog are united by applied surfaces to the upper edge of the arch formed by the sole, or more truly the bar formed by the continuation of the wall. Its point extends to or beyond the centre of the sole. The frog recedes from pressure in the na- tural foot, by having its level within the level of the other parts of the under surface of the foot, taking a third rate or degree of bearing upon the ground : the wall first ; the bar next projecting beyond it: its base also retires further from pressure than the other parts of it, and is protected by the projecting angles of the horny or lower heel. On either side, the frog is bounded by deep longitudinal excavations or channels, named the commissures of the frog ; the bottom or deepest part of these channels, forming the line of un'on of the frog with the bar, a space is thus afforded on either side of the frog, which, as an elastic body, would have been useless without it; for in vain would elasticity have been given to any part, unless sufficient room was also given for its expansion. To- wards the heels, these commissures are of considerable width, and they are there arched over by horny prolongation, from the base of the frog, named the arch of the commissure. The other extremity of the commissure grow- ing, by degrees, shallower, is lost in the level of the sole, before it approaches the arch of the frog. Seen from without, the frog makes a bold projecting appearance, as though it were a solid body of horn ; and the smiths, deceived by this appearance, entertain but indifferent notions of its real structure, and use their paring knives upon it much more freely than its thickness warrants; for it is in reality only an inverted arch of horn that is turned downwards and reversed in respect to the general arch formed by the sole and bar, so that its real thickness in horn is by no means so considerable as on a first view it would appear to be. Examined from within — that is to say, w hen the foot has been drawn forth from the hoof — the frog presents an inverted triangular arch, so intimately connected with the bar and sole, that no one would suspect it of being a distinct or divisible part, one uniform uninterrupted surface being everywhere observable on this inside : it may, however, be exhibited as a dis- tinct inserted part by making a horizontal sec- tion of the foot through the union of the bar with the side of the frog, when the difference of their structure and appearance, and the line of their applied surfaces become sufficiently visible and distinct. A hoof exposed to the weather will also be seen in its decay to se- parate at this part first, and thus readily show its distinctness from the rest of the hoof. In a perfect, well-formed foot, undistorted by shoeing, Bracy Clark observes that “ the base of the frog occupies a certain division of the general circle of the hoof, and that this division is about a sixth part of the whole circumference. By knowing this fact we are not only led to entertain more just notions of the form of the foot and the proportions ot its parts, but it affords us also an easy means of forming a pretty accurate guess of what in- jury or diminution the foot has sustained at any period of the life of the horse without previously seeing the original state of the frog.” SOLIPEDA. 739 The wings or lateral processes above de- scribed, as extending from the base of the frog, not only enclose the posterior ends or doub- lings in of the hoof, but the same horn is con- tinued around the whole upper edge or margin of the roof, forming a broad convex band, whose upper edge, projecting higher than the hoof itself, receives and covers over the ter- minating edge of the skin, where it meets the hoof, and thus protects this part from external injuries, to which it would otherwise be liable. Posteriorly it is of considerable breadth, and firmly connects the frog with the upper part of the slope of the horny heels, over which it likewise expands. This structure, first de- scribed by Bracy Clark, received from him the denomination of the “ coronary frog-band.” In the centre of the frog, as viewed from the sole, is a considerable cavity, the edges of which are furnished with rising lips or promi- nent margins of the horn ; this hollow is termed the cleft of the frog, and extends to a considerable depth. This cavity appears to serve the following useful purposes * : — 1st. It is a safeguard from rupture between the two halves or divisions into which the foot is almost separated. 2dly. By closing when pressure comes direct upon the underside of the foot, it prevents too much condens- ation of the horn at this part, and con- sequent pressure and a too solid resistance upon the soft parts beneath. 3dly. When the foot bears partially upon the ground, as by one side only, which will happen occasionally where the surface is irregular, it can extend along with that side of the foot without rup- turing, by the greater liberty it thus affords to the part, while at the same time the strength of its margin secures it from laceration. 4thly. On loose soils this indent or cavity will doubt- less assist in giving the foot a firmer hold by the irregularity it offers to the surface. It is, however, upon the inner aspect of the hoof that the most remarkable part of this structure is to be observed, for when ex- amined internally it is found that the external cleft is only the hollow base of a cone of stout horn of considerable size, which passes from it directly into the substance of the sensitive frog, and which, though completely imbedded in the soft parts, is nearly or quite as hard and tough as is the horn of the exterior of the frog which is exposed to the air. This re- markable provision seems to serve the pur- pose of uniting more firmly the two halves of which the foot of the solipeds at this part really consists, there being here an evident tendency, in the tegumentary defences of the horse’s foot, towards that division which in the ruminating quadrupeds is completely carried out. This important cone of horn Bracy Clark named the frogstay or bolt, ob- serving that, like an inserted tooth, it more firmly holds the horny to the sensitive frog, for while the sensitive frog falls into the in- verted arch of the horny frog, and is thus held most firmly in its place, this part, entering * Bracy Clark, op. cit. in the opposite direction into the sensitive frog, serves reciprocally to confirm and fix these parts together, and preserve them from external injury and dislocation. An excel- lent view of this piece of anatomy is obtained by making a perpendicular section of the foot extending through the “ heels and surrounding elastic matter.” The Sole. — This is an irregular plate of horn, which serves to close up the space or great inferior opening described by the lower circumference of the wall, and makes the third member or part of the hoof. It is usually of an arched form, more or less flat- tened, its concavity being turned to the ground, so that its centre, which is the thinnest part, is by this means removed from the degree of external pressure which the sides or bottom part of the arch have to support. Nature has secured herself, by the arrange- ment of this part, in two ways from the re- sistance which an arch of common properties would create on becoming condensed under pressure, and forcibly resisting the load brought upon it, which would have been sub- versive of the leading principles of the me- chanism of the hoof. In the first place the sole being cleft to its centre or beyond it by the large triangular opening formed at its posterior part, which, destroying the resist- ance of the arch, serves to receive the ends also of the wall of the hoof first, and is then closed and filled up by the inverted arch of the frog ; so that the ends of the hoof are thus tied in and secured from being forced asunder by the pressure from within, being thus wedged in between the frog and the sole, serving in their places the other offices already noticed, while the sole, being thus broken, has a diminished resistance in the centre. Again : the lower circumference of the arch of the sole is everywhere found abutting against the sides of the wall, which are ren- dered sufficiently flexible outwards to yield to the weight when pressed against by the de- scent and flattening of the sole, so that every provision for the elasticity of the foot is thus fully secured. The horse’s hoof is therefore fully provided with the means of preserving its form ; but this power is unfortunately grievously inter- fered with by the process of shoeing ; and it is in this country at least a very rare occur- rence to obtain an opportunity of examining a foot in its full-grown natural condition. From the above description of the foot of the horse it will be seen that, although when viewed in front it appears to be solid and single, the terms Solidungula and Solipes con- vey but a very imperfect notion of the real nature of this kind of hoof; for though the front be solid the posterior parts possess the greatest degree of elasticity, short of being actually cloven, that can be imagined from the sole being open to its centre and filled up with the frog. In such a foot as the term Solid- ungula would imply, or a continuous circle of horn, no animal could long stand, much less move, without great fatigue and pain from 3 li 2 740 SOLIPEDA. compression, which would soon become de- structive. If it were necessary to employ any single epithet to express the real nature of this kind of locomotive apparatus, Bracy Clark suggests that the term Semifissipex, or half- cloven foot, would be less objectionable, though also not exactly true, on account of the presence of the frog, which, added to the entire hoof in front, seems to afford the most essential character of this kind of foot. Fig. 514. Foot. 1, General integument ; 2, fatty mass, forming a cushion behind the great pastern joint ; 3, wall of the hoof turned back, showing the vertically lamel- lated horny processes projecting from its inner sur- face ; 4, section of the wall of the hoof ; 5, articulation between the cannon bone and the great pastern ; 6, 0, 6, aponeurotic tissues ; 7, 7, tendon of the ex- tensor longus digiti pedis. 8, 9, 10, the flexor ten- dons of the foot ; 11, 12, 13, 14, 15, expansions of the great anterior cartilage of the foot; 16, the coronary frog-band raised from the hoof ; 17, the vascular or sensitive hoof ; 18, elastic cushion of the heels ; 19, 20, 21, arteria plantaris; 22, 23, plantar veins; 25, part of the coronary venous plexus raised from its position ; 26, 27, 28, plantar nerves. Cartilages of the Foot. — On removing the hoof there are seen immediately beneath it two large elastic cartilages ranging to a great extent along both sides of the foot. Their figure is almost too irregular for comparison ; but, when seen on a lateral view of the foot, their shape may be said to resemble that of a lozenge or of a pretty fully expanded fan, fixed by its centre, which is very much thicker and more solid than the other parts, in a deep horizontal cavity or channel in the coffin bone provided for its reception ; from this central point of insertion the anterior portion of it, passing forward, nearly meets the cartilage of the opposite side in front of the foot, the great extensor tendon of the foot only separating them, with which they are likewise connected, and make a common surface. On its inside this extremity of the cartilage takes a strong ad- herence to the condyles of the coronary bone, and so closely surrounds the joint betwixt the latter and the coffin bone that the articulation ; appears to be without any capsular ligament at this part. The posterior portion of the cartilage, ranging more largely and becoming thinner as it expands itself backwards, growing at the same time more elastic in its texture, is gradually and inseparably mixed up towards the hinder part of the foot with the skin and the ligamentary elastic tissues that form the “ upper heels,” and constitute the principal materials for elasticity in these parts. Spreading also in an upward direction to a considerable height above the hoof, it terminates by a rounded, thin, and irregular edge, which is inflected inwards over the soft interior of the foot, to 1 which it forms a kind of roofing and defence. | Next, this widely distributed cartilage may be observed passing downwards, and surround- ing on every side the rough and knotty ex- tremities of the heels of the coffin bone, entering and filling up its sinuosities, and {[ taking strong adherence to these processes ; it then extends itself horizontally inwards, passing over the horny sole and bar, and, meeting the side of the sensitive frog, inti- mately unites with it, forming one inseparable mass, and together filling up the whole internal area described by the sides of the coffin bone. The upright or lateral portion of the cartilage forms, with this horizontal process inwards, a right angle, thus making together a hollow space or receptacle at the back of the coffin bone, that contains the spongy elastic stuffing of the heels, together with the tendons, trunks of bloodvessels, nerves &c., passing through this part to the sole of the foot. The upper surface of the horizontal process of cartilage is full of scabrous elevations and depressions that defy dissection, among which there exists a quantity of a gelatino-ligamentous material. Beneath, or to the under surface of this hori- zontal layer of cartilage, the sensitive sole and bar are adherent ; and, in approaching the frog, or centre of the foot, it loses its carti- laginous nature, and becomes coriaceous, or rather ligamento-coriaceous, in texture, agree- ing in this with the internal frog. The horizontal portion or process of the cartilage, named by veterinary writers the “ stratiform process ,” is of greater thickness and substance than the other parts ; it is also of a coarser grain and more elastic nature ; both portions together communicate the gene- M SOUPED A. ral boundary and form to the lateral, the pos- terior, and inferior parts of the foot ; anti when the bars or frog are thrust upwards by pressure from without, they are then acting against this same horizontal flooring, formed by the cartilage anti the frog, and met by the depression of the bones of the foot forced down from the weight of the animal ; the whole can then dilate exteriorly along with the posterior and more elastic parts of the hoof. Fig. 515. 1, Great pastern bone ; 2, lesser pastern or coro- nary bone ; 3, sesamoid bone implanted in the flexor tendon of the last phalanx ; 4, coffin bone ; 5, tendon of extensor digiti ; 6, tendon of flexor sublimus ; 7, tendon of flexor profundus ; 8, section of the posterior expansion of the great cartilage ; 9, soft cushion of the heel ; 10, section of homy hoof; 11, sensitive hoof ; 12, anterior section of the cartilage spreading over the coffin bone. The objects attained by the introduction of this admirable structure into the foot of the soliped are various, and have been well pointed out by Bracy Clark, in his excellent treatise, to which we must refer the reader for many practical applications connected with the veterinary art, that would be foreign to the objects of the present article. First, seeing that the resistance of a solid unyielding sup- port would have been inadmissible, the pedal cartilages are employed as a substitute for bone, and made to occupy a very large share in the composition of the hinder part of the foot ; for it will be remarked, the coffin bone, except by its extremity, does not extend be- yond the middle of the hoof (Jig. 515.), the posterior shape of the foot being almost wholly communicated by the cartilage, which, passing nearly around the whole coronary circle, serves to support and convey the skin to its lodg- ment in the coronary concavity of the hoof. Secondly, it serves to equalise the pressure every where over the internal surface of the hoof when under the pressure of the weight from within, during the descent of the bones 741 of the foot, and, what is singular, the hoof itself is the most solid material of these hind parts of the foot. A more important office still remains to be explained, namely, that of supplying the coffin bone with a considerable share of its capability of motion in the interior of the hoof ; for it is to be remarked that, as the coffin bone is obliged to describe in its de- scent a small portion or segment of a circle, at its back part, round its centre of motion, or rather its more fixed part (for there is none of it wholly fixed), towards the front of the foot ; so this could not so well have been accomplished had the bone itself been fixed at its upper part to the processes in front of the hoot', these being too inconsiderable to afford, in that part of the bone, the extent of motion required ; but, by the intervention of an elastic cartilage between the bone and the substance of the hoof, the bone acquires greater liberty for action, and movement of its upper parts. The cartilages of the foot, in old horses, not unfrequently become partially ossified, in which condition they are known to farriers by the name of ring-bones. Soft Parts of the Foot. — On removing the hoof, and its horny appendages situated be- neath the sole of the foot, the whole subjacent surface is found to consist of a thick, villous looking, and highly vascular membrane, moulded exactly to its inner surface, to which the name of sensitive foot is generally' applied ; or, according to the structures beneath which it is situated, it is sometimes divided into sensitive hoof, sensitive frog, &c. This struc- ture is, indeed, the matrix from which the entire corneous hoof derives its origin, and is essentially similar, in its texture and func- tions, to the soft core upon which the hollow horns of many ruminants and the vascular secreting surfaces upon which the nails and claws of unguiculate quadrupeds are formed. Externally it presents, upon the anterior sur- face of the foot, the broad vascular laminae which interdigitate with the horny' plates, pro- jecting from the interior of the hoof, as de- scribed above, so as to amplify', to a very considerable amount, the extent of surface whereby the contact between the sensitive foot and the wall is effected. This entire surface is richly supplied with nerves and bloodvessels, the latter of which open into capacious plexuses, that surmount the coronary margin of the hoof (fig. 514.), and, when injected, present a very beautiful appearance. Nervous System and Organs of the Senses. — The general arrangement of the nervous system and structure of the organs of sensation offer in the class before us no pecu- liarities of sufficient physiological importance to require a detailed description ; we append, however, figures representing the cerebral con- volutions and the base of the encephalon of the horse for comparison with similar figures given in other articles. 3 b 3 742 SOLIPEDA. Fig. 5 1 6. the latter end of June, during which period he will efficiently serve fifteen or eighteen mares. The scrotum is suspended between the thighs at a distance of about nine inches be- neath the anus, whence it is prolonged for- wards, to terminate in the prepuce (tfg. 518. a,f c)- The penis (Jig. 518. b, c, cl ) is full a foot in length even in its nndistended state, measur- ing from the bifurcation of the corpora caver- nosa (6) to the extremity of the glans (c), which latter organ is itself nearly half a foot in length, and four inches in circumference ; its shape is cylindrical, and it is covered with a soft and smooth skin. Fig. 5 1 8. Brain of the Horse, showing the Convolutions. Fig. 517. Organs of generation of the Stallion. (After JDaubenton.') Base of the Brain of the Horse, showing the origin of the Cerebral Nerves. Organs of Generation. Male Generative Organs. — The external organs of generation in the male solipeds are remarkable for their great development, and in nearly equal pro- portion are these animals conspicuous for their vigorous and fruitful generative powers, which, however, are only called into full ac- tivity at a certain season of the year, namely, in this climate, from the beginning of April till a, the scrotum ; h, c, d, the penis ; e, the prepuce j f, f, tire rudimentary mammas ; g, the left testicle removed from the scrotum; h, the epididvmus ; i,h, the upper margin of the testis; l, m, vas deferens ; n, vas deferens from the opposite side ; o, o, enlarge- ments of the vas deferens. before their termination; p, <], tendinous hands derived from the root of the tail, these, after embracing the end of the rectum, r, run along the penis, s, as far as the prepuce, t, where they terminate ; v, the urinary bladder ; x, x, vesiculffi semiuales ; y, y, Cowper’s glands. The testicles (one of which only (g) is repre- sented in the figure) are of an ovoid flattened form, each being about three inches long by two inches broad, and one inch and a half thick : the epididym us (h ) issues from its anterior part, and is composed of large tubes of a yellowish colour, bound up together in SOLIPEDA. numerous small bundles. Arrived at the pos- terior extremity of the testes, the epididymus folds back upon itself, to constitute the vas deferens ; which, at its commencement, is very tortuous, and forms a protuberance of considerable size (/). The vasa deferentia (l, m, n) are upwards of fourteen inches in length, and, during the greater part of their course, about two lines in diameter ; but to- wards their termination they become, for a length of about seven inches, much dilated, here measuring upwards of fifteen lines in circumference (oo). The caliber of the in- ternal canal does not, however, expand in proportion to the dilatation of the exterior of the duct. Female Organs of Generation. — The gene- rative organs in the female solipeds offer no variations of structure from the usual type common to placental quadrupeds. The cli- toris (fig. 519. a) is of great size, and is lodged in a cavity appropriated to its recep- tion, situated immediately above the inferior (i. e. anterior) commissure of the labia pudendi ; its glans is enclosed in an ample prepuce, above v\ hieh may be observed an orifice leading into a cavity big enough to lodge a small bean. The canal of the vagina is about afoot in length, and in its capacity corresponds with the ample dimensions of the penis of the other sex. Immediately behind the orifice of the ure- thra, the mucous membrane of the vagina forms a broad fold, which is directed forwards and lies immediately over the urethral opening : the length of this fold in the adult mare is about eight inches, and, near its middle, it is upwards of an inch in breadth. The urinary bladder is small in comparison with the size of the animal ; its shape is nearly round; and its circumference, when moderately distended, about a foot and a half. The urethra is remarkably short and capacious, the circum- ference of its canal being about three inches, while its length is only about an inch and a quarter. The orifice of the uterus ( i ) projects to the distance of about half an inch into the upper end of the vagina, and is of a rounded shape, encircled by a thick margin. The womb is made up of the body and two cornua, which latter, in the unimpregnated state, measure about seven inches in length. The ovaria and fallopian tubes present nothing remarkable in their structure or ar- rangement. Gravid Uterus. — The anatomy of the con- tents of the gravid uterus, and the arrange- ment of the membranes that enclose the foetus offer some peculiarities worthy of notice. The foetus in utero in the solipeds, is en- veloped in the usual uterine membranes, — the amnion, the chorion, and the allantoid ; but the disposition of these envelopes differs remarkably from what exists in the rumi- nants, and many other quadrupeds. The urachus (fig. 520. a ) issues from the umbilicus in company with the umbilical arte- ries and vein (b), and, in the ovum represented 743 in the figure, was found at some distance from the umbilical opening to measure about five inches in circumference, beyond which point its diameter gradually diminishes, till it reaches the point at which the amnion spreads out on all sides to envelope the foetus, where it terminates by the orifice e, and is prolonged to form the allantoid, which encompasses the rest of the cord. On the arrival of the al- lantoid at the extremity of the cord, it ex- tends itself upon the chorion to which it be- comes adherent, lining its internal surface in such a manner, that the two seem to form but a single membrane, the inner surface of which is formed bj' the allantoid ( g ), its exterior by the chorion (h). Fig. 519. Organs of generation and gravid uterus of the mare. Vagina laid open. (After Daubenton.') a , the clitoris ; b, anus ; c, rectum ; d, posterior surface of the vagina ; e, the orifice of the urethra ; f membrane which covers the urethral opening ; g, the canal of the urethra ; h, the bladder ; i, i, the ure- ters ; k. continuation of the vagina ; l, orifice of the womb ; m, foetus as seen through the transparent amnion, n ; o, portion of the umbilical cord that ex- tends from the umbilicus of the foetus as far as p, the point where the amnion spreads out ; q, portion of the umbilical cord which extends beyond the amnion to the point r, where the chorion and the allantoid become imited ; s, the allantoid ; t, the chorion seen from its outer surface ; v, a. hippomanes attached by its pedicle ; x, y, chorion adherent to the uterine walls by numerous rug* ; z, the left ovarium ; a’, the sper- matic vessels. The size of the umbilical cord gradually enlarges as it approaches the chorion, owing to the progressive dilatation of the vessels 3 b 4 744 SOLIPEDA. composing it as the}' recede from the umbi- licus. The allantoid in the mare does not form a closed bag, as it does in the ruminants, but lines about half of the interior of the cavity that exists between the amnion and the cho- rion. To form an idea of this cavity and of the space occupied by the allantoid, it will be necessary first of all to consider the amnion as a sac, in which the foetus is enclosed, and the allantoid and the chorion as forming an- other sac of larger size, by which the former is enveloped in such a manner, that an inter- space is left between the two : this interspace is traversed by the second portion of the umbilical cord as it passes from the former sac towards the latter, and in this course, the cord is enveloped by the allantoid membrane, which subsequently invests all the interior of the second sac formed externally by the chorion. Fig. 520. The aperture of the urachus pours forth a glairy fluid of a reddish colour, which is re- ceived into the cavity, the boundaries of which are described above : this fluid has a urinous smell, especially when heated, and moreover contains certain solid bodies, which have been from time immemorial dignified with the name of hippomanes , and were by the ancients sup- posed to be possessed of various mysterious qualities, and magical influences. The Hippomanes was considered, until a very recent period, to be a piece of flesh growing upon the forehead of the nascent foal ; and it was not until Daubenton presented a memoir upon this subject to the Royal Academy of Sciences in Paris *, that its real nature was understood. The hippomanes were then found to be merely masses, of a thick substance, of variable dimensions, con- tained in the allantoid cavity, which, although they might occasionally during parturition after the laceration of the membranes, become adherent to the head of the foetus, are, in reality, produced between the amnion and the allantoid mem- ji branes. These bodies are very variable in their size, and frequently several are met with, the dimensions of which vary from the size of a pea to that of a large pear, some of the latter weighing as much as five or six ounces. They are composed of a viscid substance of an olive brown colour, and frequently have irregu- larly shaped cavities in their inte- rior ; but they present no traces of organization. When cut into they seem to be made up of numerous superposed layers, and externally their surface is covered with float- ing filaments : sometimes they are found to be attached by long pe- dicles to the walls of the allantoic cavity ; but, whatever their shape, they are evidently merely sedi- mentary deposits from the fluid :n which they are immersed, and in- deed may be formed at pleasure by slowly evaporating the contents of the allantoic sac. These struc- tures are indeed by no means pe- culiar to the horse, but are fre- quently met with in other animals. The exterior of the chorion is everywhere in contact with the uterine walls, and in shape repre- sents exactly the interior of the cornua uteri, upon which it is moulded, the placenta occupying the greater portion of its extent. Mammary Glands. — It was ge- nerally believed from the time of Aristotle until a very recent period, that in themalehorse there wereno nipples or other rudiments of the * Memoires de l’Acadifmie Boyale des Sciences, anndes 1751 and 1752. Anatomy of the gravid uteris of the mare. ( After Dauhenton.) a, the urachus emerging from the umbilical opening of the foetus, accompanied by the umbilical vein ; h, and by two umbilical arte- ries ; e, continuation of the umbilical cord as far as the expansion of the amnion ; d, d, e, termination of the urachus ; f continuation of the umbilical cord ; g, g, allantois ; h, the chorion ; i, an liip- pomanes adherent to the allantoid by its pedicle ; l, m, two other hippomanes of smaller size. The other letters refer to the genera- tive organs of the foetus (a female) shown in connection with the above parts ; o, the rectum ; p, the anus ; q, the bladder of urine communicating with the urachus ; r, r, the ureters ; s, canal of the vagina ; t, orifice of the urethra ; v, first appearance of the mem- brane, which subsequently spreads over the urethral orifice ; x, x, the cornua uteri ; y, separation between their internal cavities ; z, z, the ovaria. SPINAL ACCESSORY NERVE. female mamma; except, as Aristotle expresses it, in such animals as resemble their mothers* : that is to say, in other words, that there were a few exceptional cases. Subsequent authors have stated the same concerning male solipeds in generalf, although none stated in what the resemblance consisted, or where the mammae in those furnished with them were situated ; so that even Button asserted it as a fact, that the male solipeds had no vestiges of mammae. Daubenton, however, having previously dis- covered the situation of these organs in the male ass, was led from analogy to expect their presence in the horse likewise, and soon detected them, but situated in a very unusual position, — namely, upon the prepuce of the animal. The prepuce of the stallion is found to form a kind of prominent ring around the aperture through which the penis is protruded, and it is upon this circular protuberance, close to the sides of the scrotum, that the mam- ms are situated. These organs are two in number ( ), situated at a distance of about half an inch from each other, and are easily distinguishable from the circumstance of the skin being raised into a papilla around each nipple, in the centre of which there is a shallow depression. It would seem, however, that in old horses the presence of these ru- dimentary mamma becomes less apparent. In the mare, the mammary glands are situ- ated between the thighs at a distance of about nine inches in front of the vulva. The nipples are only two in number, one on each side of the mesial line, and their distance from each other is not more than an inch and a half. As in the goat and many herbivorous quadrupeds, all the lactiferous ducts form, in the base of each gland just above the root of the nipple, a large hollow cavity, which is divided by an internal septum into two chambers, one situ- ated in front, and the other behind ; from each chamber a separate duct is derived, which passes along the nipple as far as its extremity, where it terminates. The orifices of these canals are situated, one behind, the other about a line, apart. It is owing to the presence of the reservoirs thus formed by the cavities of the mammary glands, that the lacteal secretion is permitted to accumulate in considerable quantities, until required for the nourishment of the young, or removed by human agency for the purpose of procuring the milk, which is frequently employed as an article of diet. Bibliography. — Buffon et Daubenton, Histoire Naturelle, tom. iv. 4to. Paris, 1753. Cuvier, Anato- mie Comparee. Clark, Bracy, A Series of original Experiments on the Foot of the living Horse, 4to. 1809. Clark, Bracy, Sectional Figure of the Horse, with Remarks on certain Properties of his general Framing, 4to. London, 1813. Stubbs, George, The Anatomy of the Horse, London, fol. 1766. Bourgelat, Ele'mens de l’Art V eterinaire. Lafosse, Cours d’Hip- piatrique. Vitet, Medecine Veterinaire, Lyons, 1783. ( T. Rymer Jones.') * Equi mammas non habent, nisi qui matri similes prodiere. — Arist. de Partib. Anim. lib. iv. cap. 9. f Solidungula mascula mammas non habent prceterea qure matribus similia sunt. — Rai, Synops. method. Anim. quad. &c. p. 64. 745 SPINAL ACCESSORY NERVE (part of the sixth pair of the older anatomists ; part of the eighth pair of Willis ; nervus accessorius ad par vagum ; nervus accessorius WilUsii ; the eleventh pair of Soemmering ; the beinerve of the German anatomists). This nerve is attached to, or, as it is more commonly expressed, arises from, the lateral surface of the cervical portion of the spinal chord close to the posterior roots of the spinal nerves ; and it lies between the pos- terior roots of the spinal nerves and the ligamentum denticulatum. On entering the cranium by the foramen magnum, it continues to receive additional roots or filaments of origin from the medulla oblongata. It com- mences by a very slender filament, most ge- nerally opposite the fifth or sixth posterior roots of the spinal nerves, and in its passage upwards to the interior of the cranium, its bulk is gradually increased by additional fila- ments of origin from the lateral surface of the spinal chord and from the medulla ob- longata. The filaments arising from the spinal chord pass upwards and a little for- ward to join the trunk of the nerve, so that it lies a little nearer to the ligamentum den- ticulatum than the attachments of the fila- ments forming it. After it enters the cranium by the foramen magnum, it runs forward, outward, and upward, places itself in close apposition to the posterior surface of the par vagum, and escapes from the interior of the cranium, through the foramen lacerum posterius, along with the vagus and glosso- pharyngeal nerves. The roots of the "acces- sory that arise from the medulla oblongata are placed in the same line with the lower roots or filaments of origin of the par vagum; and the upper roots of the former approach so closely to the lower roots of the latter, that it is frequently difficult to say with con- fidence where the roots of the one nerve end and those of the other begin. (Fig. 521, 3, 5.) Previous to the time of Willis, anatomists considered this nerve as constituting a part of the vagus, and to him is due the credit of first [jointing out clearly the grounds on which its separation from the vagus rests. Very great discrepancy exists in the descrip- tion of the origin of this nerve given by the best anatomists. This is explained, not only by the fact first pointed out particularly by Scarpa*, that its filaments of origin are at- tached over different extents of the spinal chord in different individuals, and sometimes to a greater extent on one side than on the other in the same individual, but also by its lower roots or filaments of origin being so slender that they sometimes cannot be ac- curately traced by the naked eye. Willis himself describes it as commencing by a very slender beginning near the sixth or seventh cervical nerve. f Scarpa ascertained that its * Abliandlung- iiber den zum achten Paare der Gehirnerven liinlaufenden Beinerven. In den Ab- handlung der rom. K. K. Josephinischen Med. Chir. Academie, Band i. Wien, 1787. f Cerebri Anatome, &c., Caput xxviii. p. 294. Amstelodami, 1666. 746 SPINAL ACCESSORY NERVE. lowest root may be attached to the spinal chord opposite the fourth, fifth, sixth, or seventh cervical nerve, but more frequently between the fifth and sixth ; and that when its roots are extended over a more limited por- tion of the spinal chord, this is compensated for by their being proportionally stronger.* Anatomists have differed as widely in their account of the particular column or tract of the spinal chord to which the roots of the spinal accessory are attached, as they have done regarding the extent of the spinal chord over which these roots stretch. This is a point in the anatomy of the nerve which has assumed greater importance since the dis- covery by Sir Charles Bell, of the separate functions of the anterior and posterior roots of the spinal nerves, and is of much more interest to the modern, than it was to the older anatomists. The filaments of origin or roots of this nerve that come from the spinal chord are attached to the chord near the posterior lateral groove separating its posterior and middle columns, and close upon the pos- terior roots of the spinal nerves, so that we can readily understand how some anatomists should describe these roots as arising from the middle column, and others describe them as springing from the posterior column, f Among the modern anatomists we find Bel- lingeri, who has attended particularly to the anatomy of this nerve, describing it as arising from the middle or lateral column of the * Huber (De Medulla Spinali, et speciatim de Nervis ab ea provenientibus, p. 13.) says that this nerve commences opposite the seventh cervical, but he afterwards speaks of it arising opposite the sixth. Lobstein (De Nervo Spinali ad Par Vagum Ac- cessory, p. 233, as reprinted in Ludwig’s Script. Neurol. Min. Selec. tom. ii. Lipsise, 1792) describes it as arising under the sixth pair of cervical nerves by a slender beginning. Bellingeri (De Medulla Spinali, Nervisque ex ea prodeuntibus, p. 74, 1823) places its origin opposite the seventh cervical nerve. Cruveilhier (Anatomie Descriptive, tom. iv. p. 899, 1835) says that its origin seldom passes below the level of the fifth pair of cervical nerves, but it may arise opposite the sixth and even the seventh pair. Bendz (De Connexu inter Nervum Vagum et Ac- cessorium Willisii, p. 22, 183G) describes its lowest root as arising from the spinal chord in the region of the fifth or sixth cervical nerves, and rarely as low as the posterior root of the seventh cervical. V alentin (Soemmering vom Baue des menschlichen Korpers. Hirn und Nervenlehre, S. 513, 1841) states that its most frequent origin is opposite the sixth, or between the sixth and seventh cervical nerves ; sometimes it arises opposite the fourth or fifth, or it may extend as far as the seventh, and in rare cases as far as the first dorsal. Krause (Handbuch der menchlichen Anatomie, Erster Band, S. 1066 : Hannover, 1842) says that it usually arises opposite the upper part of the roots of the seventh cervical, seldom higher. Bernard (Archives Generates de Mddecine, iieine serie, tom. iv. p. 410, 1844) describes it as arising by a series of bifid or trifid nervous filaments, which extend, in man, from the origin of the pneumogastric to a point opposite the fourth or fifth pair of cervical nerves. f Bolando (Recherches Anatomiques sur la Mo- elle Ablongee) and Serres (Anatomie Comparde du Cerveau, tom. i.) have stated that the lower fibres of this nerve come from the anterior column of the spinal chord. spinal chord*, while Bischofff and Bernard]; trace its origin to the posterior column ; and Bendz states that while nearly the whole of its roots come from the middle column, a few arise between the posterior roots of the spinal nerves and from the posterior column. || From my own examinations of the attach- ments of this nerve, I had arrived at the con- clusion that it arises from the posterior part of the middle column, and that its middle and inferior roots are attached along the course of the decussating fibres of the pyramidal column, which form the posterior part of the middle column of the chord. Stilling says** that the lower and middle roots of this nerve can be traced to the anterior grey substances in the chord, from which the anterior roots of the spinal nerves arise, and that, in an anatomical point of view, they must be re- garded as performing the same functions as the anterior roots of the spinal nerves ; while the upper roots, or those which are attached to the medulla oblongata, differ in a marked manner, in regard to their origin, from the lower and middle roots. He states that these upper roots above the first cervical nerve arise from a grey mass in the medulla ob- longata, which he styles the accessory -kernel (accessorius-kernff ), and that they resemble closely the lower filaments of origin of the par vagum. These upper roots of the acces- sory do not arise from the gelatinous sub- stance from which, according to Stilling, the posterior roots of the spinal nerves spring, yet they come into closer relation w'ith it the nearer they approach to the commencement of the roots of the vagus. The upper fi- bres of the accessory, though not continuous with the posterior roots of the spinal nerves, are yet, he believes, analogous to these; and this view is strengthened by their presenting the same connection with the roots of the hypoglossal as is found between the roots of * De Medulla Spinali, Nervisque ex ea prode- untibus, pp. 51. 55, 1823. f Nervi Accessorii Willisii Anatomia et Physio - logia, p. 11. Darmstadii, 1832. J Archives Generates de Medeeine, 4ifeme serie, tom. iv. pp. 409, 410, 1844. § Tractatus de Connexu inter Nervum Vagum ct Accessorium Willisii, pp. 22. 39. Hauniae, 1836. || Lobstein (De Nervo Spinali, in Ludwig’s Scriptures Nevrologici Minores Selecti, tom. ii. p. 233.) also describes some of the filaments of origin of the spinal accessory as coming from the spinal chord between the fasciculi which consti- tute the posterior roots of the spinal nerves, and has represented these in fig. 1. Those who may wish to ascertain the opinions of other anatomists as to the particular column of the spinal chord into which this nerve is implanted, and the extent of its attachment to the cervical portion of the spinal chord, may consult the monographs of Bischoff and Bendz quoted above, and especially that of the former of these authors. «|f On some points in the anatomy of the me- dulla oblongata, in Edinburgh Medical and Surgical Journal for 1841. ** Ueber die Textur und Function der Medulla Oblongata, pp. 55. 57. Erlangen, 1843, If He describes the position and structure of this accessorius-kern at p. 23. of the work quoted. SPINAL ACCESSORY NERVE. 747 the posterior and anterior spinal nerves at And in another place he says, “ I believe that their origin. the filaments from the posterior roots, which The spinal accessory in its course within join the accessory, leave it again to proceed the spinal canal frequently forms communi- to the posterior root of the first cervical.”* cations with the posterior root of the first From this he concludes that the accessory cervical, and much more seldom with the contains no sensiferous filaments. Muller, on posterior root of the second cervical nerve.* * * § When these communicating filaments come from the second cervical, they are generally few in number. This communication between the spinal accessory and the posterior root of the first cervical is, according to Lobstein, more frequently present than absent. f When the posterior root of the first cervical joins itself, either in whole or in part, to the spinal accessory, a branch of equal size generally leaves the accessory, either at the point where it is joined by the posterior root of the first cervi- cal, as figured and described by Asch J, or a little above this junction, as figured by Hu- ber §, and described by Bellingeri.|| This branch, after leaving the accessory, proceeds outwards, approaches the anterior root of the first cervical, and takes the place of the posterior root of that nerve.1 ®[T When the posterior root conies from the accessory, it generally presents a ganglion in the usual position. Sometimes, however, though rarely, this ganglion is found on the accessory where the posterior root of the first cervical leaves it to join itself to the anterior root. This ganglion was first pointed out by Huber ; its existence has been denied by Lobstein, Asch, Haller, and Scarpa, and it has again been described by Bellingeri. I have seen this gan- glion twice, and it was present on one side only. It becomes an interesting question in a physiological point of view to know, whether or not the whole of the filaments of the pos- terior roots of the spinal nerves which join themselves to the accessory, again leave it to form the posterior root of the first cervical. Bellingeri answers this question in the affirm- ative. “ The filaments,” he says, “ coming from the posterior roots to the accessory are not intermixed, but only approximated, so that they can be separated by slight traction.”** * Scarpa states (opus cit. p. 395.) that in a great number of bodies he examined with a special refer- ence to this point, he found a communication be- tween the accessory and the posterior root of the second cervical only in two instances. j- Circa harum radicularum, quse pro radicibus posticis primi paris habenter, communicationem illud notamus, quod saepius accessorium subire, quam eundern intactum relinquere observenter. Opus cit. p. 223. J De Primo Pare Nervorum Medullar Spinalis, tab. x. fig. 2. ; et explicatio, p. 335. Ludwig Scrip. Nevr. Min. Sel. tom. i. § Opus cit. || Opus cit. p. 80. Monro secundus has also given a representation of this communication between the accessory and posterior root of the first cervical. Observations on the Structure and Frmctions of the Nervous System, tab. x. fig. 2. 1783. Bischoff states (opus cit. pp. 34. 82.) that in none of the numerous instances in which he dis- sected the accessory in the lower animals, did lie. ever observe any filaments of the posterior roots of the spinal nerves join themselves to it. ** Opus cit. p. 81. the other hand, has adduced some unusual anatomical arrangements in this nerve, which may be regarded as favouring the opinion that it contains sensiferous filaments independant of those which it may receive from the pos- terior roots of the spinal nerves. He men- tions an instance f, which he elsewhere J describes at considerable length, where the posterior root of the first cervical nerve oil the right side was not present, and where its place was supplied by two bundles of fila- ments from the superior part of the spinal accessory. The upper of these bundles, at least, came from the medulla oblongata. Upon the posterior root of the first cervical thus constituted, a ganglion was formed while it was still within the theca vertebralis. The upper fibres of the posterior root of the second cervical of this side joined themselves to the accessory, but no nervous filaments were attached to the spinal chord in the usual position of the posterior root of the first cervical. On the left side, the posterior root of the first cervical presented its usual appearance, and was connected to the spinal accessory by some filaments of communi- cation. The filaments of the accessory arising from the medulla oblongata did not, as on the right side, divide themselves into two parts, one of these becoming the substitute of the posterior root of the first cervical : but the whole ran upwards into the accessory nerve. || Muller also states that Hyrtl has often seen a ganglion upon the accessory nerve opposite the entrance of the vertebral artery into the in- terior of the cranium ; and that Remak showed him an instance of a ganglion upon the spinal accessory at its passage through the foramen lacerum. “ I do not, however, affirm,” Mul- ler remarks in reasoning from these cases, “ that the spinal accessory always contains originally sensiferous filaments, but leave it doubtful.” “ But in the case,” he continues, “ where the nervus accessorius forms an inti- mate connection with the posterior root of the first cervical, or any other nerve, we may suppose an interchange ; and this, in the same degree, will render probable the idea of Monro, * Ibid, p. 79. f Archiv. fur Anat. und Physiol. 1834, p. 12. + Idem opus, 1837, pp. 279 — 281. § Arnold (Bemerkungen iiber den Bau des Hirns und Rtickenmarks, &c., S. 181 — 183 ; Zurich, 1838) has published remarks upon this anomalous instance in the origin of the posterior root of the first cervical from the accessory, the object of which is to en- deavour to show that Muller had misinterpreted the facts observed. Among other things urged with this view, is the circumstance that the pos- terior root of the first cervical does not arise usually in the same line with the posterior roots of the other spinal nerves, but somewhat anterior to these. AVe cannot, however, believe that so experienced and accurate, an anatomist as Muller is, could fall into any such mistake as is here insinuated. 748 SPINAL ACCESSORY NERVE. that the communication of the spinal accessory with the posterior root of the first, or with any other spinal nerve, will be an equivalent to it for a posterior root.” We have already seen that Stilling concludes, on anatomical grounds, that those filaments of the accessory that come from the medulla oblongata con- tain centripetal filaments.* The spinal accessory passes through the foramen lacerum posterius in a canal formed by the dura mater, common to it and the vagus, but they are occasionally separated from each other as they enter this canal by a bridle of arachnoid, or of the dura mater. Soemmering has pointed out that the acces- sory does not perforate the dura mater like the other nerves, but is, as it were, insensibly surrounded by this membrane, j- One or two filaments generally pass be- tween the accessory and the superior gang- lion o r ganglion jugnlare of the vagus, as they lie in the foramen lacerum posterius. Hein states that he has more than once distinctly observed, as also Krause has remarked, the superior five, or even six filaments of the root of the accessory approximate very closely to the ganglion jugulare of the vagus, and partly enter into its formation, so that a junction between the vagus and accessory had already taken place in this ganglion, before the fila- ments of the accessory had been fully collected to form together the trunk of this nerve. J As the spinal accessory is passing through the foramen lacerum, it is in close proximity to the posterior surface of the par vagum, and it there divides into its two branches — its internal and external branches. The former, or the internal, is composed of the filaments forming the upper roots of the nerve {Jig. 521, 1 1.), and entirely, or almost entirely, of those coming from the medulla oblongata; and it joins itself to the vagus immediately below the ganglion jugulare of that nerve. The passage of the accessory through the foramen lacerum posterius, its division into two branches, and the distri- bution of the internal branch as far as it is known, have been already described in the art. Par Vagum, vol. iii. pp. 883. and 890 , and need not be repeated here. The external branch, composed of those fibres which arise from the spinal chord {Jig- 521, 12.), proceeds downwards, outwards, and backwards behind the internal jugular vein, in front of the occipital artery, and be- hind the posterior belly of the digastric and stylo-hyoid muscle, and reaches the inner sur- face of the sterno-cleido-mastoid muscle at the lower part of its upper third. In con- * Stilling further states (p. 59) that in an ana- tomical point of view we may regard the upper roots of the accessoiy forming the internal branch of that nerve as being composed of centripetal and centrifugal filaments, exactly like the vagus. ■j “ Non reliquorum nervorum more, suh arcu durse membranse fertur, sed insensili quasi modo a dura membrana obducitur.” De Basi Encephali, &c., p. 104, reprinted in Ludwig’s Scrip. Nevr. Min. Sel., tom. ii. X Muller’s Archiv. 1844, p. 337. tinuing its course downwards and outwards, it here generally perforates the sterno-cleido- mastoid ; at other times it is only closely con- nected to it by cellular tissue ; but in both cases it gives branches to this muscle. In this part of its course it is strengthened and anastomoses with twigs of the third and second cervical nerves. Continuing its pro- gress downwards and backwards it anastomo- ses with twigs of the fourth and fifth cervical nerves, and throws itself into the inner surface of the trapezius muscle, among whose fibres it is ultimately lost. Comparative anatomy of the spinal accessory. — The origin and distribution of this nerve in the mammalia does not essentially differ from what is found in the human species.* Willis states that this nerve is not only pre- sent in the mammalia, but also in birds and fishes f ; but the existence of it in the two latter divisions of the vertebrata has been subsequently denied by many excellent ana- tomists. “ If an animal,” says Mr. Shaw, “ does not perform part of the act of respira- tion by muscles which run from the skull to the chest, no spinal accessory is found. The truth of this observation may be shown by the dissection of any of the larger birds, but the most extraordinary proof is to be found in the neck of the camel. The constitution of the neck of this animal is like that of birds ; there being a succession of short muscles along the side of the neck, and attached to the vertebrae, but no long muscle passing from the jaw to the sternum to assist in breathing, as in other quadrupeds.” J It appears, however, that in the camel this nerve is present, but it is smaller and differently distributed from what it is in the horse.$ Serres found it in three of the larger birds, Weber in some fishes, and Bis- choff hasgiven descriptions and representations of it in several birds, reptiles, and fishes. In these animals the upper part only of this nerve seems to be present, for it does not stretch downwards along the spinal chord to the same extent in them as in the mammalia. The whole of this nerve, in these animals, throws itself into the vagus, while a branch leaves the vagus after it has escaped from the cranium, and taking the place of the external branch of the accessory is distributed to the muscles of the neck in birds and in reptiles, and to the muscles which move the pectoral fin in fishes. || In the chimpanzee, the spinal accessory, after passing through the foramen lacerum, divides into two branches. The in- ternal runs towards the larynx, into which it penetrates above the os-hyoid. It is placed between the superior laryngeal nerve and stylo-hyoid ligament, and passes behind the internal carotid artery to the superior hyoi- * Dissections of this nerve upon several mammalia are given in detail by Bischotf and Bendz. f Opus cit. p. 295. j London Medical and Physical Journal, vol. xlix, p. 458, 1823. § Vide note by Defermon, at p. 527 of tom. ii. of the Archives Generates de Me'decine, 1823. || A full account of the comparative anatomy of this nerve is given by Bischotf. SPINAL ACCESSORY NERVE. 749 dean region (la region hyoidienne superieure), where it terminates. The external branch passes downwards below the sterno-cleido- mastoid muscle to reach the trapezius, in which it is chiefly distributed.* Fig. 521. From Bendz, reduced one-half. a, part of cerebellum cut across ; b, medulla ob- longata ; c, spinal chord ; a, floor of fourth, ventricule ; b, calamus scriptorius ; cc, posterior pyramidal bodies; d, right restiforme body obliquely divided; f f lateral columns of spinal chord ; h h, posterior columns of spinal chord ; i, posterior longitudinal fissure ; k k, posterior roots of spinal nerves ; 3 3, roots of vagus nerve ; 4 4, roots of glosso-pharyngeal ; 55 5, roots of nervus accessorius; 6, ganglion of the root of the vagus or superior ganglion ; 7, auricular branch of vagus ; 8, right ganglion petrosum of glosso-pharyngeal; 9, ramus anastomicus of Jacob- son ; 10, communicating branch between the superior ganglion of the vagus and the ganglion petrosum ; 11, roots of the accessory which form its internal branch ; 12, roots of the accessory which form its external branch ; 13, glosso-pharyngeal nerve ; 14, trunk of the vagus ; 15, pharyngeal branch of vagus ; 16, filaments of this branch that come from the vagus ; 17, filaments of this branch that come from the internal branch of the accessory; 18, ganglion of the trunk of the vagus or inferior ganglion ; 19, nervus laryngeus superior ; 22 22, communicating branches between the ganglion of the trunk of the vagus and the superior ganglion of the sympathetic ; 23, fibres of the internal branch of the accessory which do not enter into the for- mation of the ganglion of the trunk of the vagus ; 24, branch from these fibres which joins itself to the external branch of the superior laryngeal nerve. Physiology of the accessory. — The peculiar origin and course of this nerve, and particularly its intimate connection with the par vagum, have formed the basis of most of the specula- tions on its functions since the time of Willis. It was maintained by Willis that this nerve, from its connection with the par vagum, re- gulates those involuntary movements of the neck and arm caused by the emotions and * Recherches d’Anatomie Comparee sur le Chim- pansd: par W. Vrolik, p. 40. Amsterdam, 1841. passions.* Lobstein likewise believed that the spinal accessory joins the vagus for the purpose of connecting itself with the in- voluntary functions, and he supposed that its paralysis might also affect the move- ments of the pharynx and larynx. f Others have maintained that it is a nerve of involun- tary motion from the particular portion of the spinal chord in which it is implanted. It is, as is well known, one of Sir Charles Bell’s respiratory nerves, arising as he supposed from a particular tract in the spinal chord to which he gave the name of respiratory tract, and is therefore, according to this view, a nerve of involuntary motion. Bellingeri believes that the lateral tract of the spinal chord, from which the accessory arises, presides over the instinc- tive and sympathetic movements, and that it is consequently a nerve of involuntary motion. J Arnold §, Scarpa ||, Bischoff^f, Valentin **, and Longet f f , have maintained that the accessory stands in the same rela- tion to the vagus as the anterior roots of the spinal nerves do to the posterior roots. Ac- cording to this last view, the vagus does not originally possess any motor filaments, but derives them from the spinal accessory. The two first of these authors came to this con- clusion on anatomical grounds alone ; the three latter, from experiments upon these nerves in living animals, as well as from their anatomy. Bernard has arrived at the conclusion that it is entirely a motor nerve, and that it enables the larynx and pharynx, and muscles of the neck in which it is distributed, to partake in the production of the phenomena of phona- tion, but that it does not assist in any of the true respiratory movements.^ Dr. Todd and Mr. Bowman ||||, on the other hand, believe that the internal branch of the accessory is composed of afferent nerves, and that the mode of implantation of this nerve in the cen- tral organs of the nervous system serves to bring the sentient surface of the lungs and air- passages into immediate relations with the roots of all those nerves which animate the great muscles of respiration, the phrenic, the external thoracic, the cervical plexus, and the motor fibres of the spinal accessory and vagus nerves. All experimenters agree that the external * Opus cit. caput xxviii. f Ibid. pp. 345, 346. J Ibid. pp. 89, 90. § Der Kopftheil des vegativen Nervensystems. Heidelberg, 1831. || De Gangliis Nerv. deque Essentia Nervi Inter- cost. Ann. Univers. di Medieina, 1831. Nervi Accessorii Willisii Anatomia et Phy- siologia, 1832. ** De Functionibus Nervorum Cerebralium et Nervi Sympathici, 1839. ft Anatomie et Pbysiologie du Systeme Nerveux, &c., tom. ii., 1842. It appears that this idea had been previously suggested by Gorres (Exposition der Physiologie, Coblentz, 1805, as quoted by Muller). §§ Archives Generates de Medecine, 4ibme serie, tom. iv. and tom. v., 1844. 1111 The Physiological Anatomy and Physiology of Man, vol. ii. p. 130. 750 SPINAL NERVES. branch of the spinal accessory is a motor nerve. We found that when it was embraced firmly within the forceps, or tied tightly soon after it had emerged from the foramen laeerum, the animal gave indications of suffering * * * § ; but an experiment of this kind does not enable us to decide whether these sensiferous filaments were originally contained in the accessory, or were derived from the neighbouring nerves. Mr. Shaw has detailed an experiment to show that the movements which it imparts to the sterno-mastoid, and to the trapezius are not voluntary, but respiratory. f In our experi- ments, and in those subsequently performed by Bernard, these muscles acted in unison with the muscles of respiration after the spinal accessory nerves had been divided. While all experimenters agree that the ex- ternal branch of the accessory is chiefly if not entirely composed of motor filaments, they' have arrived at discrepant conclusions re- garding the functions of the internal branch. Volkmann J, Van Kempen §, and Stilling ||, observed no movements of the muscles in which the internal branch of the accessory is distributed, on irritating the roots of this nerve within the cranium ; while in those of Bischoff, my own, those of Valentin 51, Lon- get** * * §§, Heinj--j-, Morganti JJ, and Bernard §§, partly consisting of irritating the roots of the nerve within the cranium after death, and partly, as in those of Bischoff, Longet, Mor- ganti, and Bernard, by lesions of the nerve in living animals, anti observing their effects upon the movements of the muscles in which it is distributed, proofs of its being a motor nerve were believed to be obtained. We think that this evidence is sufficiently strong to justify the belief that the internal branch of the accessory does contain motor filaments; * Edinburgh Medical and Surgical Journal for January, 1838. Valentin states (opus cit. pp. 58. 62.) that he succeeded in increasing the action of the heart by irritating the trunk of the accessory ; but Van Kempen (opus cit. p. Go) repeated this experiment without success. f London Medical and Physical Journal, vol. xlix. j Muller’s Archiv. 1840. § Essai Experimental sur la Nature Fonctionelle du Nerf Pneumogastrique : Louvain, 1842. In giving the results of Van Kempen’s experiments in the art. ParVagum, foot-note atp. 891, vol. iii. upon the effects of irritating the roots of the vagus within the cranium, I have inadvertently written the pa- lato-glossus muscle instead of the palato-pharyngeus or pharyngo-staphylin muscle, as one of the muscles seen to contract in this experiment. I may also here correct another error in the same article : at p. 900, it is stated that Longet believes that the secretion of the gastric juice is greater after section of the vagi than in the sound animal ; while in fact he states that it is diminished by section of the vagi, and that this diminution in the secretion may be explained on mechanical grounds. || Bischoff’s Bericht iiber die Fortschritte der Physiologie im Jalire 1842, S. 154. In Muller’s Archiv. 1843. 5f Opus supra cit. ** Opus supra cit. tf Muller’s Archiv. 1844. Jl Omodei, Annali Universali di Medicina. Juli, 1843. §§ Opus supra cit. but it is at the same time highly probable that it is partly composed of sensiferous anil afferent filaments, and if so, its constitution must be similar to the vagus nerve, with which it be- comes so closely incorporated. In the art. Par Vagum, sufficient proof has been ad- duced to satisfy us that the opinion that the spinal accessory furnishes all the motor fila- ments contained in the trunk of the vagus, is no longer tenable. ( John Reid.) SPINAL NERVES (Les Nerfs rachidicns, Fr. ; Die Rueclcenmarksnerven, Germ. ; I Nervi Spinali, Ital.) are thirty-one pairs, and are dis- tributed to the neck, and the upper extremi- ties, the trunk and lower extremities. They are divided into Cervical, Dorsal, Lumbar anil Sacral : the first division comprising eight ; the second, twelve ; the third, five ; and the fourth, six. Their general and special cha- racters, and their apparent and absolute con- nexion with the spinal chord having been already described *, we shall limit the details of this article to their ultimate distribution. Each spinal nerve, after the union of its roots, divides into an anterior and posterior branch, the former having generally a much more complicated and extensive distribution than the latter. It will be convenient there- fore for the purpose of description to enter first into a consideration of the posterior branches. The posterior branch of the first cervical or sub-occipital nerve is larger than the anterior, and passes internal to and below the vertebral artery, between the arch of the atlas and the occipital bone, to gain the triangular space be- tween the rectus capitis posticus major, the su- perior and inferior oblique muscles. It is here imbedded in a considerable quantity of fat and dense cellular membrane, and having directed itself from before, backwards, and slightly from belowupwards,dividesinto a series of branches. Two external branches are sent to the two oblique muscles : an internal ascends to the rectus capitis posticus major, and which having supplied this, terminates in the minor : another filament is directed to the anterior aspect of the complexus near to its occipital attachment: and the terminal branch descends, generally perforating the inferior obliquely, and anastomoses with the posterior branch of the second cervical nerve. The posterior branch of the second cervi- cal nerve emerges from between the lower border of the posterior arch of the atlas, and the lamina of the axis, and is larger than any of the posterior branches of the cervical nerves, and three or four times greater than the anterior branch of the same nerve. It appears at the lower border of the inferior oblique, and having passed a short distance horizontally inwards, winds round this muscle to the anterior aspect of the outer part of the complexus, which it perforates. It inclines outward and upwards between it and the * Vide Nervous System, vol. iii. p. 657. SPINAL NERVES. trapezius, passes through the latter, and ter- minates in the skin in the occipital region as the great occipital nerve, coursing along with the occipital artery but lying internal to it. Before becoming great occipital, it gives off at the lower border of the inferior oblique a branch to supply this muscle and a superior and inferior anastomotic branch to commu- nicate with the first and third cervical. When passing along the anterior surface of the corn- plexus, numerous branches are given off to this muscle, the trapezius, and splenius. Those for the last muscle are more numerous ami larger than the branches, for the two others are directed to the anterior aspect of the muscle, and one or more of them perforate the complexus before reaching it. The posterior branch of the third cervical is smaller than the second, but larger than the fourth, and situated more externally, emerg- ing from between the transverse processes of the second and third cervical vertebra. It is directed inwards, between the opposed surfaces of the complexus and semispinalis colli towards the median line, and having reached the sides of the spinous processes of the vertebrae, di- vides into ascending and horizontal cutaneous branches. The ascending branch, after a short course, perforates the inner border of the complexus and trapezius, and becomes cuta- neous. It continues its course close to the median line, as far as the region of the oc- ciput, the inner and lower part of which it supplies on the internal side of the great occi- pital nerve. The horizontal branch passes between the ligamentum nuchas and the inner border of the complexus, and after having perforated the tendon of the trapezius, terminates in ex- ternal small cutaneous filaments. The nerve prior to division, and at the outer border of the semispinalis colli, communicates by one or more filaments with the posterior branch of the second cervical. From the anastomosis between the communicating branches of the posterior roots of the three first cervical nerves, results an irregular plexus placed between the complexus and outer part of the semi- spinalis colli, and consequently nearly in a line with the transverse processes of the superior cervical vertebrae. From this posterior cervical plexus, numerous branches arise to supply the complexus, splenius, and semispinalis colli. The anastomosis between these posterior branches is, according to Cruveilhier, some- times deficient. The posterior root of the fourth cervical nerve varies much as to individual size, but is al- ways smaller than the preceding. It passes downwards and inwards between the com- plexus and semispinalis colli, and having reached the side of the median line, perforates the tendons of the splenius and trapezius, and becomes cutaneous. In its course it supplies these muscles, and occasionally terminates in the splenius without going to the skin. The posterior branches of the fifth, sixth , seventh, and eighth cervical nerves have a similar course to the fourth, but decrease in 751 size from above downwards. The fifth and sixth usually pass between the opposed sur- faces of the semispinalis colli and complexus, give branches to these muscles, and perforate the inner part of the tendons of the splenius and trapezius, to terminate in the skin at the lower part of the nape of the neck. The posterior branches of the seventh and eighth cervical nerves pass either through the deep-seated fibres of the semispinalis colli, or between it and the multifidus spin®, give branches to these two muscles, perforate the tendons of the trapezius and splenius, and terminate by ramifying, the one on the skin above the scapula, the other over the integu- ment, as far as about the spinous process of the third dorsal vertebra. The inter-trans- versaies muscles, cervicalis ascendens, tra- chelo-mastoid, and transversalis colli, receive numerous small filaments from these nerves almost immediately after their appearance in the neck. The posterior branches of the dorsal ( tho- racic) nerves are much smaller than the an- terior, and are directed backwards between the ascending costo-transverse ligaments and the sides of the vertebrae. Having reached the outer border of the semispinalis dorsi and multifidus spinas, they divide into external and internal branches, the latter being muscular and cutaneous in their distribution, the former only muscular in the eight upper. In the first eight the internal branches are larger, in the last four much smaller than the ex- ternal. The external or muscular branches of the eight superior pass between the sacro-lum- balis and longissimus dorsi, and give off nu- merous filaments to supply these muscles, and the levatores costarum ; that of the first send- ing a few filaments to the cervicalis ascendens, trachelo-mastoid, transversalis colli, and sca- leni muscles. The internal branches wind either over the posterior aspect of the semispinalis dorsi, or between it and the multifidus spinas, and having supplied these muscles with numerous filaments, reach the sides of the spinous pro- cesses ; here they perforate the rhomboid, latissimus dorsi, and trapezius, the last muscle very obliquely, and become cutaneous, being principally distributed to the skin at the back part of the scapular region. The external branches of the four inferior pass obliquely downwards and outwards be- tween the sacro-lumbalis and longissimus dorsi, communicating with each other in their course, and at the outer border of the former muscle perforate the tendon of the latis- simus dorsi, and become cutaneous, some of the lower filaments being capable of being traced over the glutasal region. The internal branches of the four inferior are remarkably small, and are lost either in the substance of the multifidus spinas, or semi- spinalis dorsi. The cutaneous filaments from the posterior branches of the dorsal nerves given off on the one hand from the internal, and on the other from their external divisions. SPINAL NERVES. 752 are situated somewhat in a line with the angles of the ribs, so that the)' become more external in proportion to their inferior posi- tion. The posterior branches of the lumbar nerves are analogous in their distribution to the four lower dorsal branches, having an external large musculo-cutaneous, and small internal muscular divisions. The external branches run along the deep surface of the longissimus dorsi, and at its outer edge perforate the tendon of the latissimus dorsi, and terminate in cutaneous filaments directed over the crest of the ileum to the glutaeal region, as far as on a level with the great trochanter. The internal branches are lost in the substance of the multifidus spin®. The posterior branches of the sacral nerves exist as distinct branches within the spinal canal, and consequently differ from the cer- vical, dorsal, and lumbar, which become dis- tinct trunks after the main trunks have issued from the spinal or intervertebral foramina. They decrease in size from above downwards, being extremely small, and passing out of the posterior sacral foramina, the fifth coming out between the sacrum and coccyx. They form a minute anastomosis with each other, and with the corresponding branch of the last lumbar, and after having given filaments to the lower part of the erector spin®, per- forate the tendon of that muscle, and are distributed to the skin over the sacrum and coccyx, and immediately around the anus. The anterior branches of the spinal nerves are much larger than the posterior branches, the two upper cervical forming the only ex- ception. They form intricate plexuses in the neck, the lower part of the spine and sacrum, the nerves given off from those in the first situation being principally intended for the neck and upper extremities ; in the two last for the lower extremities. The intervening series represented by the thoracic nerves, being comparatively simple in their distribution, do not form plexuses. The Anterior Branches of the Cervical Nerves. The anterior branch of the first cervical nerve, smaller than the posterior, is di- rected between the occipital bone and the transverse process of the atlas, passes over the outer edge of the vertebral artery, and appears at the inner side of the rectus ca- pitis lateralis. It then descends, and forms an anastomotic arch with the anterior branch of the second, in front of the transverse process. In its course the rectus capitis lateralis, and rectus capitis anticus minor receive one or more filaments, and it also sends a filament into the canal for the vertebral artery, and which communicates with the trunk of the second cervical between the transverse pro- cesses of the atlas and axis. From this ana- stomotic arch are given off filaments which communicate with the lingual and par vagum and superior cervical ganglion of the sym- pathetic. The anterior branch of the second cervical nerve, also much smaller than the posterior passes forwards between the transverse pro- cesses of the atlas and the axis, being con- cealed by the levator anguli scapulas, splenius, and first inter-transverse muscle, and divides into an ascending branch, passing in front of the transverse process of the atlas, to com- municate with the first cervical; and a de- scending branch. The descending branch soon subdivides, and gives several filaments of communication with the superior cervical ganglion; one small filament to communicate with the par vagum, another enters the rectus capitis anticus major, and the last concurs to form the cer- vical plexus. Anterior branch of the third cervical nerve, larger than the posterior, and twice as large as the preceding, passes between the verte- bral artery and inter-transverse muscles, and having given branches to the levator anguli scapulae and rectus capitis anticus major, com- municates above with the descending branch of the second, below with that of the fourth, anti in the interval with the superior cervical ganglion, and then again bifurcates to enter into the formation of the cervical plexus. The anterior branch of the fourth cervical nerve, of the same size as the preceding, communicates above with the third, below with the fifth cervical, in the middle with the superior cervical ganglion, and then enters into the formation of the lower part of the cervical plexus. The cervical plexus (the deep cervical plexus) is composed of the primary and secondary anastomosing arches of the anterior branches of the four upper cervical nerves. These anastomosing arches are subject to consider- able variation, though generally formed by each nerve bifurcating, and, after having com- municated with the nerve above and below, again reuniting in a more or less uniform manner prior j to giving off their terminal branches. The plexus is situated deeply at the upper anterior and outer part of the neck behind the posterior edge of the sterno-mastoid, in front of the scalenus posticus, external to the rectus capitis anticus major, the carotid artery, jugular vein, and par vagum. It con- stitutes the chief contents of the posterior superior cervical triangle, and is surrounded by a large quantity of loose cellular membrane, absorbent glands, and fat, and immediately in- vested with a prolongation of the deep cervical fascia, which renders the dissection of the nu- merous branches as they immediately proceed from it, difficult. It communicates internally by several delicate filaments with the superior and middle cervical ganglia of the sympathetic; below with the upper part of the brachial plexus, and externally with the spinal acces- sory, giving several filaments to the muscles with which it is in immediate relation. The branches given off' from the cervical plexus may be divided as follows, into j Superficialis colli. Superficial ascending -j Auricularis magnus. Occipitalis minor. SPINAL NERVES. 753 Superficial descending Deep f Supra-r.lavicular. \ Supra-acromial. {Communicating branches. Muscular. Phrenic. The superficial^ colli (superficial cervical nerve) takes its origin from the middle of the plexus in company with, but anterior to the great auricular, the anastomosing branches of the second and third cervical nerves concurring to form it. It emerges from behind the pos- terior border of the sterno-mastoid about the middle of the neck, and is directed horizontally forwards and inwards, behind the external jugular vein, and between the sterno-mastoid and platysma, and at a variable point divides into two branches, an ascending and descend- ing, the former larger than the latter. The ascending branch almost immediately divides into numerous filaments, some of which supply the platysma myoides ; one or two ascending along the external jugular vein. The greater number are directed upwards and forwards to the upper part of the platysma and digastric muscle, communicate with the deeper seated filaments given off' from the portio dura, and becoming cutaneous, supply the skin over the region of the sub-maxillary gland, the chin (communicating with the sub- mental nerve), and the lower part of the cheek ; some filaments being directed to the median line to communicate with the corresponding nerve of the opposite side. The descending branch forms a loop, the concavity of which looks upwards and inwards, perforates the anterior part of the platysma, a little above the middle of the neck, gives off one or two twigs to accompany the anterior jugular vein, and terminates in the skin about the hyoid bone. The aui icularis magnus (the auricular nerve) arises in common with the trunk of the super- ficial cervical from the anastomosing branches between the second and third cervical. It emerges from behind the posterior border of the sterno-mastoid, above the superficial cer- vical, and in front of the occipitalis minor. It winds round the edge of the sterno-mastoid, and is directed along it obliquely upwards and inwards to the lower part of the parotid gland on a level with the angle of the jaw, reaches to the anterior border of this muscle, and divides into a superficial and deep terminal branch. It gives off’ before dividing several filaments between the parotid gland and the skin, and others which pass through the sub- stance of the former to terminate in the skin in the malar region, where it communicates with the facial nerve. The superficial branch courses upwards in the parotid fascia, and on a level with the antitragus divides into several filaments, which are distributed on the one hand to the concave surface of the auricle, particularly the concha ; and on the other, to the anterior border of the helix, and the vertical groove in front of it. The deep branch (anterior mastoid), having perforated the parotid gland, and crossed the auricular branch of the facial, with which it communicates, becomes placed behind the auricle of the ear, ascends along the anterior part of the mastoid process, communicates with the occipitalis minor, and terminates by supplying the skin at the back of the ear, some filaments passing on to its upper border. The occipitalis minor (mastoid, external oc- cipital) comes from the posterior part of the cervical plexus, taking its origin from the second cervical. It appears at the posterior edge of the sterno-mastoid, behind and above the great auricular. It passes upwards parallel with the great occipital nerve directed by the border of the splenius, which it occasionally perforates, to the occipital region behind the mastoid process ; communicates with the great auricular externally, and with the great occipital nerve internally, and ends by terminating in the skin over the parietal bone. There occa- sionally occurs a small accessory nerve, be- tween the auricularis magnus and occipitalis minor. This is directed along the posterior border of the sterno-mastoid, and is distributed to the skin over the mastoid process. The supra-clavicular and acromial nerves, form the termination of the cervical plexus, and exist as two primary trunks, which usu- ally about the level of the posterior belly of the omo-hyoid, divide and subdivide into numerous branches, which traverse super- ficially the posterior inferior triangle of the neck, first passing behind the platysma, then between it and the skin. The internal series ( sternal ) are directed forwards and inwards, over the lower part of the sterno-mastoid, the inner third of the clavicle, and end in the skin over the upper part of the sternum, and upper and inner part of the pec- toralis major. The middle filaments ( mam - mary') pass over the centre of the clavicle, and are distributed to the skin of the pectoralis major and the mammary gland, and commu- nicate with branches of the intercostal nerves. The posterior ( clavicular ) pass downwards and outwards over the outer third of the cla- vicle, and ramify in this skin over the anterior and outer part of the deltoid. The acromial nerves are larger than the cla- vicular, and are, ordinarily, two in number. They pass obliquely outwards, downwards, and backwards, over the lower part of the superficial aspect of the trapezius, give some filaments to this muscle, which communicate with the spinal accessory nerve, and having reached the acromion, divide into numerous cutaneous branches, which are lost in the skin covering the spine of the scapula, and the outer and back part of the deltoid. The communicating branches have been al- ready partly described in the consideration of the formation of the plexus ; and are formed by different filaments, which are connected with the trunk of the sympathetic, its upper and middle cervical ganglion, as also with the par vagum and lingual. The internal deep branch is represented by the communicans noni or internal descending cervical. It takes 3 c SPINAL NERVES. 754 its origin principally from the descending di- vision of the second cervical, and having re- ceived a filament from the first cervical, comes down the neck external and posterior to the internal jugular vein. At the middle or lower third of the neck, it describes a curve ; the concavity of which looks upwards, and com- municates with the descending branch of the lingual (descendens noni), by winding in front of the internal jugular vein. This nerve is subject to considerable variation, bifurcating, occasionally, before communicating with the descendens noni, and giving off now and then one or two delicate filaments to the same muscles, usually supplied by the latter nerve : viz. the sterno-hyoid, sterno-thyroid, and omo-hyoid. The external communicating branches are represented by a rather larger anastomotic branch, which communicates at an acute angle with the spinal accessory ; and by the muscular branches. These accompany the spinal accessory, communicate more or less with it, and are distributed to the trapezius, le- vator anguli scapulae, the rhomboideus minor, and upper part of the rhomboideus major. The phrenic nerve (diaphragmatic, internal respiratory) appears at the lower and anterior part of the fourth cervical nerve of which it appears the continuation. It receives, how- ever, some accessory filaments from the third and fifth cervical, which exist either as single or plexiform twigs, or are occasionally absent. The secondary sources of origin are, in fact, subject to considerable variation. It is di- rected along the anterior edge of the scalenus anticus, inclining slightly inwards between the subclavian artery and vein, before entering the superior opening of the thorax. It passes behind and outside the carotid artery and jugular vein, and communicates with the fifth, sixth, and, occasionally, with the seventh cervical and pneumogastric nerves, and in- variably with the sympathetic. The exact points of communication of these different nerves is by no means determinate ; some- times taking place in the neck ; at others, in the upper part of the chest. It crosses the direction of the internal mammary artery, and reaching the anterior mediastinum, glides down in front of the root of the lung between the pericardium and inner aspect of the former, and terminates in the diaphragm. In its course within the chest, it gives several fila- ments to the remains of the thymus gland ; some very minute twigs of communication with the superior cardiac plexus ; and re- ceives, occasionally, a very delicate filament of communication, coming down obliquely, from the descendens noni : on reaching the diaphragm, the nerve divides into a series of superior and inferior filaments ; the former, long and diverging from each other, enter the upper surface of the muscle, having first passed for some distance between the muscle and the pleura covering it; the latter per- forate the muscle, diverge, and run for some distance between the muscle and peritoneum, and enter its under surface. The right phrenic is shorter and more ver- tical in direction, and more anterior in its position than the left, being directed in the upper part of the chest, along the vena cava superior. Several of its internal terminal filaments pass behind the vena cava inferior, communicate with the left, and end in the coeliac plexus ; a few, however, communi- cate, also, with some twigs of the pneumo- gastric. The left phrenic turns over the apex of the heart; and, besides its general distribu- tion, gives filaments to the crura of the dia- phragm, anastomosing filaments to the solar and coeliac plexus, and some communicating branches to the opposite nerve. The anterior branches of the four inferior cervical and first dorsal nerves are very large, and form, therefore, a remarkable contrast to the four upper cervical, situated above them. They pass through the intervertebral foramina, between the two scaleni ; the eighth cervical passing between the foramen common to the last cervical and first dorsal vertebra. Having given off several filaments to communicate with similar filaments from the inferior and middle cervical ganglion, and some small twigs to the scaleni, the different branches unite together, so as to constitute the bra- chial plexus; the first, communicating above with the fourth cervical, and sending a twig to the phrenic. The union of the different branches takes place in the following manner: — the anterior branches of the fifth and sixth descend obliquely outwards, and, after a course of about one or two inches, unite at an acute angle. Those of the eighth cervical and first dorsal, which are not so oblique in their direction, similarly unite; but a little | more internally : this union taking place, oc- casionally, between the scaleni, either pair of branches almost immediately bifurcating after their union. The trunk of the seventh passes distinct between the two upper and lower branches, as far as the lower border of the clavicle in the upper part of the axilla, and there bifurcates ; the upper part of the bifur- cation being connected with the lower part of the bifurcation of the first united cord, and the lower with the upper of the last united cord. Secondary bifurcations and anasto- moses take place at more or less acute angles, anil thus the brachial plexus is constituted. The brachial plexus (axillary') is situated at the inferior and lateral part of the neck, in the posterior inferior cervical triangle, where it is covered in by a considerable quantity of fat, cellular membrane, and lymphatic glands, which separate it from the external jugular vein. The scalenus anticus bounds it in front and internally ; the scalenus posticus in the oppo- site direction ; and in its course from between these muscles to the clavicle, it is crossed by the omo-hyoid muscle, transversalis coli, and humeral vessels, and more superficially, by the supra-clavicular and acromial branches of the cervical plexus. Having passed from beneath the clavicle, it becomes placed be- tween the coracoid process of the scapula and the first digitation of the serratus magnus, SPINAL NERVES. Infra-clavicular and anterior, and external to the first rib, and there divides into its terminal branches. In the neck, the plexus is situated superior, pos- terior, and external to the artery ; but as the trunks gradually converge towards the axilla, and the terminal branches again diverge, the artery comes to be bounded by some inter- nally, by others externally. The plexus is broad above, where it represents the base of a triangle, and narrow below at its termina- tion at the upper part of the axilla. The different branches of the plexus may be divided into those given off above, and those below the clavicle : — the former, for the levator anguli scapula, subclavius, rhom- boid, and serratus magnus; the latter, for the upper extremity and its muscles. Supra-clavicular { jocular supra-scapular. |_ oubscapular. Internal cutaneous. External cutaneous. Median. Ulnar. Musculo-spiral. _ Circumflex. Of the muscular branches. The nerve for the rhomboideus takes its origin from the an- terior branch of the fifth cervical, immediately after it has quitted the intervertebral foramen ; but is frequently given off from the cervical plexus : it is, consequently, deeply seated. It either perforates the scalenus porticus or winds round it, to get between it and the levator anguli scapula; ; continues along the costal surface of the latter muscle, and then passes to the same surface of the rhomboi- deus, as far as its lower part, frequently sup- plying, in its course, the levator anguli sca- pula;, which, in many cases, however, receives filaments from a distinct nerve arising above it, and taking a similar course. The nerve to the serratus magnus (external respiratory, posterior thoracic), situate at the posterior and upper part of the plexus, arises from it by two delicate roots, which come off from the lower edge of the fifth and sixth cervical, immediately after they have passed the intervertebral foramina. It receives, sometimes, a twig from the seventh. It is directed downwards and outwards, and reaches the thorax between the subscapularis and ser- ratus magnus, passing behind the axillary vessels. It passes along this muscle inferior, to the long thoracic artery, and terminates in its lower part, by numerous filaments. The nerve for the subc/avius is very small, but always present, and is given off from the anterior part of the united trunk of the fifth and sixth cervical. It passes down anterior to the subclavian artery, and enters the mid- dle of the muscle. The remainder of the muscular branches are very small, and come off from the lower and anterior part of the plexus, being princi- pally derived from the seventh cervical : some pass behind, and others, in front of the ax- illary artery, enter the axilla, and are distri- buted to the posterior surfaces of the pecto- ralis major and minor. They are known 755 under the collective name of anterior or short thoracic. The supra-scapular nerve, larger than the long thoracic, issues from the upper and back part of the plexus, from the united root of the fifth and sixth cervical at their angle of union. It is directed downwards, outwards, and backwards in company with the supra- scapular vessels, passes behind the trapezius and coracoid process to the notch in the upper edge of the scapula, beneath the ligament which converts this notch into a foramen, and which separates it from the supra-scapular vessels. Having reached the supra-spinal fossa, and supplied the supra-spinatus muscle, it winds along the concave external border of the spine, and reaches the infra-spinal fossa, supplying the infra-spinatus. From the in- ferior filaments one or two twigs can be traced to the teres minor. The subscapular nerves are intended for the latissimus dorsi, teres major, and subscapularis. That for the first muscle is the largest and longest. It arises from the plexus above, and internal to the circumflex nerve, passes down in the axilla between the subscapularis and serratus magnus, parallel, but posterior to the long thoracic, and terminates bj' reach- ing the lower border of the latissimus dorsi, where it enters its substance. It gives off occasionally in its course the branch from the teres major, which usually, however, arises from the plexus below it. This nerve passes downwards and outwards at the subscapularis, and enters the anterior surface of the teres major. The nerves for the subscapularis are : a small one, generally constant as to its origin arising high up from the same source of origin as the circumflex, passing behind the axillary artery to the upper part of the superficial surface of the subscapularis ; the other larger, and frequently derived from the circumflex, to be distributed to the middle of the muscle. The internal cutaneous, the smallest of the terminal branches of the brachial plexus, and situated most internally, takes its origin princi- pally from the last cervical and first dorsal. It descends, covered in by the brachial aponeuro- sis, along the inner aspect of the arm, between the median and the ulnar, and concealed above by the axillary artery. Deeply seated in the axilla, in leaving this cavity it inclines slightly forwards and outwards in company with, but anterior to, the basilic vein ; and at a variable distance from the elbow joint, generally a little below the middle of the arm, divides into external and internal cutaneous branches : both of which perforate the fascia. In this part of its course the internal cutaneous gives off in the axilla a small cutaneous filament, which, having communicated with the second or third intercostal nerve, perforates the fascia, and supplies the skin on the inner part of the arm as far as the internal condyle. The external terminal branch, the continua- tion of the trunk in the arm, and the larger of the two, divides into two or three twigs, which pass either in front or behind the 3 c 2 750 SPINAL NERVES. median basilic vein, some occasionally pass- ing in front, and some behind. The exter- nal filaments course down the anterior and inner part of the fore-arm, following the di- rection of the median vein, and communica- ting with branches of the external cutaneous : the internal follows the course of the ulnar vein, communicating with a twig of the ulnar nerve at the lower part of the fore-arm. Both terminate in the integument over the annular ligament. The internal branch , frequently perforating the fascia lower down than the external, passes behind and then below the median basilic vein, to the inner and back part of the fore-arm, and having communicated a little below the elbow with the accessory internal cutaneous, continues its course, and supplies the integument along the inner and back part of the fore-arm as far as the inner edge of the hand, communicating, in its course, with the innermost filaments of the external branch. Placed behind and internal to the internal cutaneous nerve, is the cutaneous nerve of Wrisberg (the accessory nerve of the internal cutaneous), considerably smaller than it. It arises from the united chord formed by the seventh cervical and first dorsal. It descends along the inner part of the axilla, and com- municates with the cutaneous branch of the second intercostal. Coursing down the arm on a plane behind the ulnar and internal to the basilic vein, it perforates the fascia about the lower third, and, becoming cutaneous, di- vides into anterior filaments, communicating with the internal cutaneous : and posterior, communicating with the internal cutaneous branch of the musculo-spiral. The external cutaneous (musculo-cuta- neous : perforans casserii), larger than the preceding, but smaller than all the other nerves, and most external, is formed by the fifth and sixth cervical. It is directed ob- liquely downwards and outwards in front of the tendon of the subscapularis to the inner aspect of the coraco-brachialis, perforates this muscle (occasionally, however, passes behind it without perforating), and then becomes situated obliquely between the biceps and bra- chialis anticus. At a short distance from the elbow it emerges from beneath the outer border of the biceps, and internal to the supinator longns ; and at the bend of the elbow, after passing behind the median ce- phalic vein, hcomes subcutaneous. In this part of its course the external cutaneous nerve gives off a series of muscular branches. Of the two branches to the coraco-brachialis, the upper, having perforated it, terminates in the short head of the biceps. The branches to the biceps unite separately or by a common trunk, and one of them per- forates the biceps, and supplies the elbow- joint, being here situated to the outside of the superficial flexor tendons. The branches for the brachialis anticus are several, and penetrate the muscle by its superfi- cial surface. The continuation of the external cutaneous nerve in the fore-arm is represented by a series of internal and external cutaneous branches, which pass down along either side of the radial vein. The former near the wrist joins with a branch from the radial nerve, and gives oil' a filament which perforates the fascia, and accompanies the radial artery to the outer and back part of the wrist, where it supplies small twigs to the front and back of the radio- ulnar articulation. The latter gives filaments to the outer and back part of the fore arm, as far as the wrist. The median nerve. — The largest of the bra- chial plexus, and situated between the external cutaneous and the ulnar, arises by two roots, the external common to the median, and the external cutaneous : the internal common to the median, the internal cutaneous, and the ulnar. The fifth, sixth, seventh, and eight cervical and first dorsal nerves consequently concur to form it. Between its two roots is placed the axillary artery. It passes along the inner side of the arm in company with the axillary artery to the bend of the elbow, lying at first to the outside of the vessels, and then a little above the middle of the arm, crosses to its inner side, occasionally, however, con- tinuing all along to its outside. It is slightly overlapped by the inner border of the biceps, having the brachialis anticus to its outside : the latter muscle separates it inferiorly from the ulnar nerve. The upper part of the in- ternal cutaneous nerve runs along its inner side. It sinks into the bend of the elbow behind the semilunar fascia, and in front of the brachialis anticus, passes between the two heads of the pronator radii teres, and is then conducted along the forearm between the flexor digi- torum sublimis and profundus to the annular ligament, behind which it passes; and at the lower border of this becomes expanded, and di- vides into a series of terminal digital branches. The median nerve gives off’ no branches during its course along the arm, with the exception of an occasional communicating branch to the inusculo-cutaneous below the level of the insertion of the coraco-brachialis; and a branch which is usually found coming off from the anterior part of the trunk a little above the elbow. This is directed along the brachialis anticus to the pronator teres, which it supplies, and sends a few filaments back- wards to enter the articulation. The branches given off in the fore-arm arc muscular, interosseous, and cutaneous. The muscular branches for the lower part of the pronator teres, flexor carpi radialis, pal- maris longus, and flexor sublimis, are generally derived from a primary branch, which arises behind the pronator teres a little below the elbow-joint ; the lower part of the flexor sublimis, however, receiving several smaller branches from the main trunk. The branches for the flexor longus pollicis and flexor digi- torum profundus are given off lower down, there being generally one for the former and two for the latter, the outer part of which only is supplied ; the inner part of the muscle being supplied by the ulnar nerve. The anterior interosseous nerve is the most SPINAL NERVES. 757 deeply seated branch of the median, coming off at an acute angle from the trunk, between the origin of the deep-seated muscular brandies. It runs vertically downwards in company with, but to the radial side of, the corresponding artery, in front of the interosseous membrane between the flexor digitorum profundus and flexor longus pollicis, giving on either side small filaments to them. Having reached the upper edge of the pronator quadratus, it passes behind that muscle, and terminates either by sending numerous filaments into its posterior surface, or, after having supplied it, perforates the lower aperture of the interos- seous membrane, and reaches the back of the carpus. The palmar cutaneous branch is given off at the lower fourth of the fore-arm, passes for- wards from beneath the tendons of the flexor sublimis, and behind the fascia, which it per- forates a little above the wrist, and divides into an external filament, which, having com- municated with the radial, terminates in the skin of the vola major, and an internal de- scending over the annular ligament to be lost in the skin of the upper part of the palm. The terminal digital branches of the median are derived from two primary branches, into which the flattened and expanded nerve di- vides, after having passed from beneath the annular ligament. These are external and internal, the former supplying the muscles of the thumb, and sending off three digital branches for the thumb and radial side of the index finger, and rather smaller than the latter, which gives off two digital branches for the opposed sides of the index and middle, and the middle and ring finger. The muscular branch passes in a slightly curved manner out- wards and upwards, and terminates in fila- ments for the supply of the abductor, opponens and flexor brevis pollicis. The first digital nerve is directed obliquely downwards and outwards in front of the tendon of the flexor longus pollicis, and near the head of the metacarpal bone, crosses it to its outer side, and continues its course to the extremity of the outer side of the anterior aspect of the first phalanx, where it terminates in dorsal anti palmar branches. The dorsal branch winds on to the back of the last pha- lanx, communicates with the radial, and sup- plies the skin at the root of the nail ; the palmar continues in the original course of the nerve to the skin at the extremity of the thumb. The second digital nerve, not so oblique in its direction as the first, crosses over the adductor pollicis, gives a filament to it, and is conducted along the inner side of the flexor longus pollicis tendon to the ulnar side of the thumb, sending in its course some fila- ments backwards to communicate with the dorsal branches of the radial, and terminating in a similar manner to the preceding branch. The third digital nerve is directed in front, and to the outside of the first lumbrical muscle, gives a filament to it, and reaches to about the middle of the outer side of the proximal phalanx of the index finger, where it divides into dorsal and palmar branches. The dorsal branch passes on to the back of the phalanx, communicates with one of the dorsal cutaneous nerves, to form a nerve which ends in the integuments of the back part of the last phalanx : the palmar branch passes in the original direction of the nerve, and terminates on the outer side of the distal pha- lanx by again dividing into palmar and dorsal branches, having a similar distribution to the two first nerves. The fourth digital nerve passes in front of the second interosseous space, gives a filament to the second lumbrical muscle, and about the middle of this space divides into two branches, which are directed along the op- posed sides of the middle and index fingers. The fifth passes downwards and slightly in- wards in front of the third metacarpal space, gives a filament to the third lumbricus, com- municates by a delicate filament with the ulnar, and at the middle of this space ter- minates in two branches for the opposed sides of the middle and ring finger. The termina- tion of the divisions of the fourth and fifth digital nerves, and the branches given off from them, are exactly similar in distribution to the third digital nerve, giving off, like it, on the proximal and distal phalanx, a dorsal branch. Each of the digital nerves, although running along the sides of the fingers, and giving off in their course numerous cutaneous filaments, which are directed towards the axes of the fingers, are not observed to anastomose with each other. The median nerve in the palm of the hand is situated on a plane anterior to all the flexor tendons, and the trunk before dividing is situated half art inch or more above the level of the superficial palmar arch of arteries which crosses in front of its three internal branches. The accompanying digital arteries are placed somewhat behind, and further from the longitudinal axes of the fingers than the nerves, which, however, in their course send numerous small filaments w hich wind around them. The ulnar nerve, somewhat smaller than the median, arises from a trunk common to it, the internal cutaneous and the inner head of the median. The first dorsal and last cer- vical are consequently principally engaged in forming it. Almost immediately after its origin it is directed slightly inwards and out- wards from the median, and behind the in- ternal cutaneous, and at the lower part of the axilla appears deeply seated at the inner aspect of the arm, being directed in front of the triceps extensor muscle. Below the level of the coraco-brachialis it perforates the in- ternal intermuscular septum, and becomes surrounded by several fasciculi, derived from the inner head of the triceps, and passes be- hind the intermuscular septum to gain the space between the internal condyle and ole- cranon, being here situated betw'een the two heads of the flexor carpi ulnaris. It now in- clines downwards and slightly outwards along 3 c 3 758 SPINAL NERVES. the inner part of the coronoid process of the ulna, and then takes a vertical course down the fore-arm, covered over by the flexor carpi ulnaris, and between it and the flexor digi- torurn profundus. It gradually inclines to the surface, and at the lower third of the fore- arm becomes sub- aponeurotic, and passes from between the flexor carpi ulnaris and inner tendon of the flexor sublimis to the lower part of the anterior surface of the annular ligament, passing along it in a distinct sheath with the artery, in close contact with, and external to, the pisiform and unciform bones, and divides into its terminal branches. In the upper part of the arm the ulnar nerve is in relation with the axillary artery, which is placed between it and the median, nearer however the latter. In the upper part of the fore-arm it is about half an inch or more dis- tant from the artery, but gradually inclines, so as to come in close relation with, but internal to it, in the two lower thirds of the fore-arm, and in the palm of the hand. The ulnar gives off no branches in the arm ; and the first that comes oft' from it, is when the nerve is placed between the two heads of the flexor carpi ulnaris. There are several small articular filaments which enter the inner part of the joint, and three or four which are distributed to the above muscle. In the upper third of the fore-arm some filaments are again given off' to the flexor carpi ulnaris, and others for the supply of the inner half of the flexor digitorum profundus. About the mid- dle a small branch is given off, which, after sending satellite filaments to accompany the ulnar artery, perforates the fascia, and be- comes cutaneous to communicate with the internal cutaneous. The largest branch, how- ever, given off from the ulnar, comes away about two inches above the wrist-joint, and is named, its dorsal branch (dorsalis carpi ulna- ris : internal dorsal nerve). This winds down- wards and inwards, and having passed be- tween the tendon of the flexor carpi ulnaris and the bone, perforates the fascia at the back of the fore-arm, and becomes cutaneous a little above the styloid process. It runs then along the inner edge of the carpus ; and on the posterior annular ligament terminates in tvvo branches. The inner branch passes along the inner and back part of the metacarpal bone, and phalanges of the little finger, supply- ing the integument as far as its extremity, and sending in its course some small filaments to the abductor minimi digiti. The outer branch crosses obliquely the tendon of the extensor minimi digiti, and on the fourth interosseous space sub-divides. The inner sub-division at the extremity of the space bifurcates in order to supply the opposed sides of the little and ring finger. The outer sub-division at the lower extremity of the third interosseous space having communicated with the dorsal branch of the radial, similarly bifurcates for the supply of the integument of the opposed sides of the middle and ring finger. The dorsalis carpi ulnaris, independently of the above branches, sends numerous filaments to the inner and back part of the wrist and hand, and communicates above with the external or posterior cutaneous. The terminal branches of the ulnar nerve are two in number, a superficial external, and deep internal. — The former, after a very short course, divides into two branches, a small internal, and large external. The internal branch passes along the ulnar side of the little finger to its extremity, giving filaments in its course to the muscles of the little finger. The external passes obliquely across the flexor tendons for the ring finger, gives a filament to the fourth lumbricus, and one of communication with the median, and over the fourth inter- osseous space at a variable distance from its inferior extremity bifurcates : the divisions of the bifurcation being distributed in a similar manner with the median to the opposed sur- face of the ring and little finger. The deep branch is directed backwards and outwards between the abductor minimi digiti, and the flexor brevis to the posterior aspect of the adductor minimi digiti, having first given off on the palm a small branch which sends filaments to these three muscles. It passes downwards in a curved manner, the convexity of the curve looking downwards and inwards, and after a short course passes at an acute angle behind the deep palmar arch of arteries. No branches come off from its con- cavity. From its convexity and back part and outer termination are derived filaments which supply the two inner lnmbricales, the palmar and dorsal interossei, the adductor and flexor brevis pollicis. The deep or per- forating interosseous branches can be traced through the two layers of interossei to the skin on the back of the hand, where they com- municate with the dorsal cutaneous from the radial and ulnar nerves. The musmlo-spiral nerve ( radial ) slightly larger than the median, arises from the inner and back part of the plexus, and is formed particularly by the three inferior cervical and first dorsal nerves. The trunk from which it arises also gives origin to the circumflex nerve. It passes at first from before back wards, running behind the ulnar, and in front and below the circumflex nerve, and having crossed the con- joined tendons of the teres major, and latissi- mus dorsi, inclines downwards, backwards and outwards to the posterior surface of the hu- merus, between it and the long head of the triceps. It continues gradually inclining more outwards, till it reaches the lower third of the arm where it gains the outer aspect of the bone, and here it passes forwards in company with the superior profunda artery, to the an- terior and outer aspect of the arm lying in- ternal to the outer head of the triceps which it perforates. It is now directed between the supinator longus and brachialis anticus, and then between the latter and extensor carpi radialis longior, and, having reached the outer and anterior part of the elbow- joint, divides into an anterior and posterior terminal branch. The branches given off from the musculo- SPINAL spiral in the arm are numerous, and may be arranged into Internal cutaneous. Branch for the internal head of the triceps. Branches for the long head of the triceps. Outer head and anconmus. Cutaneous filaments to the arm. External cutaneous. The internal cutaneous is the first branch of the musculo-spiral, and continues for some distance deeply seated to the fascia, which it perforates above the middle of the arm, and descends as one or two filaments along the inner and back part of the arm to the elbow, where they communicate with the posterior filaments of the accessory internal cutaneous. The branch for the internal head of the tri- ceps is the next that is given off. It is a delicate, long nerve, which is directed along the surface of the inner portion of the triceps, running behind the ulnar nerve to within three or four inches of the elbow-joint, when it enters the substance of the muscle. The branches for the long head of the triceps are numerous, and enter its anterior surface. The superior branch is reflected upwards, and can be traced as far as the axillary origin of the muscle. The inferior or descending branch is the longest, and courses downwards to near the olecranon before entering it. The branch for the outer head of the triceps and anconceus, given off externally to the branches for the long head, is a long slender nerve. It passes down between the outer and middle head to the outside of the olecranon, sup- plying the outer head in its course, and ter- minating in the anconceus by entering at its anterior surface. The external cutaneous branch is given off below the middle of the arm, as the musculo- spiral is commencing its anterior and outer course. It passes along the outer and back of the arm, and divides into two or three delicate descending filaments which supply the skin, and terminate on the back of the carpus be- tween the posterior branches of the external cutaneous, radial, and dorsalis carpi ulnaris with which they communicate. The musculo-spiral nerve, before giving off its terminal branches, sends filaments to the muscles between which it passes, viz. the bra- chialis anticus, supinator longus, and extensor carpi radialis longior. The anterior terminal branch ( radial nerve') is the apparent continuation of the musculo- spiral nerve, though smaller than the posterior terminal branch. It passes between the supi- nator longus and brevis, lying on the latter, and over-lapped by the former, and gradually approaches, in its descent of the fore-arm, the radial artery ; so that at the middle it is in close contact with, but external to, the vessel. Having arrived at the lower third of the fore- arm, or a little above, it twists round the deep surface of the tendon of the supinator longus, and appears beneath the fascia on the outer part of the fore-arm, and after a short sub- NERVES. 759 aponeurotic course, perforates the fascia, and divides about acouple of inches above thesty- loid process into an external large, and internal terminal-branch. The external branch passes along the outer aspect of the styloid process ; and at the proximal part of the wrist sends a communicating loop inwards, to be connected with the cutaneous palmar branch of the me- dian. It then descends on the dorsum of the thumb, and supplies its external border. The internal branch crosses obliquely the extensor ossis metacarpi and primi internodii pollicis, and divides into a series of branches which supply the ulnar side of the thumb : both sides of the index finger, and the radial side of the middle. These different branches furnish, in their course along the carpus, several cutaneous filaments, and some small twigs which com- municate with the perforating interosseous of the deep branch of the uinar nerve. The most internal division communicates with the dorsalis carpi ulnaris. The two terminal branches of the radial are subject to much variation : the external being sometimes larger than the internal, and supplying either both sides of the thumb, or both sides of the thumb and the radial side of the index finger. The internal branch occasionally unites with the outer division of the dorsalis carpi ulnaris, and supplies the opposed sides of the middle and ring fingers. The deep terminal branch ( the posterior interosseous or muscular) is larger than the anterior, passes downwards and backwards along the inner aspect of the exterior carpi radialis brevis, gives filaments to it, and reaches the surface of the supinator brevis, supplies it, as it passes obliquely downwards, backwards, and inwards through its substance, to emerge at its lower and posterior portion. It here divides into a posterior and anterior series : the former supplying the extensor carpi ulnaris, the communis digitorum, and minimi digiti, entering at their anterior aspect the latter the deep-seated muscles. One of the latter has a somewhat remarkable course ; is longer and larger than the rest; and passes along the posterior surface of the extensor ossis metacarpi and primi internodii; and at the lower part of the fore-arm becomes placed between the interosseous ligament and the extensor seeundi internodii, and indicator, sup- plies these muscles with one or two twigs, and is conducted in front of the posterior annular ligament to the back of the carpus, where it assumes a gangliform enlargement, from which numerous filaments radiate for the supply of the ligaments and carpal articulations. The circumflex nerve ( axillary ) is the most posterior of the terminal branches of the bra- chial plexus, and is occasionally given off from the musculo-spiral, usually, however, taking its origin from a trunk common to it, and to that nerve, external to wh;ch it is situated. After a short course in the axilla, it soon leaves that space by passing downwards and outwards over the upper part of the axillary border of the subscapularis to enter the quadri- lateral space above the teres major, below the 3 c 4 Internal Posterior External 760 SPINAL NERVES. teres minor, and between the humerus and long head of the triceps to terminate in the deep surface of the deltoid. It gives off in this course branches to the subscapularis and teres minor; that for the latter entering the lower border of the muscle, and prior to dividing into its deltoid branches. — The cutaneous nerve of the shoulder passes from belli nd the posterior border of the deltoid, perforates the fascia, and divides into a series of radiating branches, which supply the skin at the upper and back part of the shoulder. The deltoid branches ramify through the sub- stance of the muscle as far as its insertion, and from one of them a filament is given off to the capsular ligament of the shoulder joint. The anterior branches of the dorsal ( inter- costal) nerves are twelve in number, the first escaping between the first and second dorsal vertebrae, and the last between the last dor- sal and first lumbar. They run more or less parallel to each other without forming plexuses, and are destined to supply the tho- racic and abdominal parietes, and the skin about the arm and axilla. They present general and special characters. Each branch runs outwards, from its origin, being sepa- rated from the posterior root by the in- tervention of the anterior costo-transverse ligament, to reach the intercostal space, be- tween the pleura and external layer of the in- tercostal muscles, and below the intercostal vessels. Having communicated by one or two filaments with the thoracic ganglia of the sympathetic, these nerves are continued be- tween the two layers of the intercostals, to about midway between the spine and the sternum, and here they divide into cutaneous and intercostal branches. The cutaneous branches perforate, in a very oblique manner, the external layer of intercostals ; and, after a short course, forwards and outwards, between them and the serratus rnagnus, either escape between the digitations of the serratus mag- nus and external oblique, or perforate their fibres, and divide into anterior and posterior branches. This division takes place some- times when the trunks of the cutaneous nerves are covered by the serratus and oblique. The jiosterior branches are reflected backwards and upwards, and, after a course of an inch or two between the latissimus dorsi and the skin, terminate in the latter. The anterior branches are directed downwards and forwards, or horizontally, and, after a longer course than the posterior branches, terminate, like them, in the skin. The intercostal branches, though somewhat smaller than the cutaneous, represent the con- tinuation of the anterior branches of the dorsal nerves. They continue in the original course of the latter, below the lower edge of the ribs on the one hand, and the costal carti- lages on the other ; and near the border of the sternum above, and the linea alba below, perforate the muscular fibres, and become cutaneous. The trunks of the intercostal nerves and their continuation give off numer- ous filaments to the supply of the intercostal muscles, and several extremely delicate twigs, which frequently pass over the inner aspect of the ribs, to communicate above and below with each other in the intercostal spaces. The special characters of the intercostal nerves are as follow : — The first dorsal nerve, ascending in front, and across the neck, of the first rib, to assist in the formation of the brachial plexus, gives off only a small intercostal nerve. This comes away soon after the nerve has left the intervertebral foramen, and is directed along the inner surface of the first rib, to the first intercostal space, without giving off a middle cutaneous branch, and passes along the lower edge of the cartilage to the sternum, by the side of which it perforates the intercostal muscles, and terminates on the skin, at the upper and fore part of the thorax. The second dorsal nerve crosses obliquely over the second rib, external to its neck, to gain the lower part of the first intercostal space, and again crosses the second rib, to reach the second intercostal space on a level with the middle of the former. Its cutaneous branch is of large size, and, supplying the arm with cutaneous branches, is named the inter- costu-humcral, which perforates the second intercostal space. In traversing the axilla it gives off a branch of communication to the accessory internal cutaneous, and one to com- municate with the second intercosto-humeral ; the latter united nerve sending filaments to the skin at the upper and anterior part of the arm. Two or three filaments represent the termination of the nerve, cross the lower part of the posterior boundary of the axilla, and terminate in the skin, at the upper and back part of the arm. The cutaneous branch of the third dorsal (the second intercosto-humeral) is smaller than the second, and passes through the third in- tercostal space : it divides into an anterior and posterior branch ; the former winds up- wards, forwards, and inwards, over the lower border of the pectoralis major, to terminate in the mamma and integument ; the hitter, having communicated with the second intercostal, sends filaments to the axilla, and terminal branches, which are directed to the outer and anterior part of the axilla to supply the skin, at the upper and back part of the arm. The cutaneous branches of the fourth and fifth dorsal nerves send filaments inwards, to supply the mamma; and filaments backwards, over the superficial surface of the latissimus dorsi, to supply the skin over the anterior and outer part of the scapula. The intercostal nerves of the eighth, ninth, tenth, and eleventh dorsal nerves perforate the intercostal spaces of the false ribs, pass through the costal attachments of the diaphragm, to get between the external and internal oblique, as far as the border of the rectus, where they give off small cuta- neous branches. Entering the sheath of the rectus, they proceed along the posterior sur- face of the muscle, and terminate, by giving off some filaments, which ramify in its inner part ; and others, which perforate the anterior SPINAL NERVES. 701 layer of the sheath, at a variable distance from the linea alba, to supply the skin at the anterior part of the abdomen. The twelfth dorsal nerve is larger than those that have preceded it, and gives a filament of communication to the anterior branch of the first lumbar nerve. It is directed ob- liquely downwards and outwards, following the course of the last rib, along the lower border of which it runs, passes behind the anterior layer of the transversalis fascia be- tween it and the quadratus lumborum, and, on a level with the apex of the rib, divides into two branches. The cutaneous branch, larger than the abdominal, or continuation of the trunk, perforates, obliquely, the external and internal oblique, gives them some small branches, and then becomes superficial, crosses over the crest of the ilium, and divides into a series of divergent filaments, which lose themselves in the skin of the middle of the glutaeal region. The abdominal branch or con- tinuation of the nerve passes between the in- ternal oblique and transversalis, supplies these muscles, communicates with the first branch of the lumbar plexus, and terminates in the rectus and pyramidalis, and the skin over them. The anterior branches of the lumbar nerves are five in number, intervening between the corresponding branches of the dorsal and sacral nerves. They increase in bulk from above downwards, communicate with each other by anastomosing branches, and with the lumbar ganglia by filaments, which come from the latter, or the main trunks. These fila- ments of communication with the sympathetic, vary in number from two to five, and are in close relation with the convexities of the bodies of the lumbar vertebrae. Several nerves are also given to the supply of the psoas muscle. The anterior branch of the first lumbar nerve is small, much resembling the anterior branch of the last dorsal. Having quitted the inter- vertebral foramen, it immediately divides into three branches ; two external and small, viz. : — the great and small muscu/o-cutaneous ; the other internal and vertical in direction, and forming the anastomosing branch with the second. The anterior branch of the second lumbar nerve, twice as long and broader than the first, gives off the genilo-crural and external cuta- neous, and communicates by a long anasto- mosing branch with the third. The anterior branch of the third lumbar nerve, nearly twice as large as the second, is directed downwards and outwards, and gives off, at an acute angle, a large external branch, concurring to form the anterior crural, and an internal, the obturator nctve: it communicates with the fourth nerve by one branch con- nected with the main trunk, or by two con- nected with its two branches. The anterior branch of the fourth lumbar nerve is somewhat larger than the third. It divides into an external branch connected with the external division of the third, to com- plete the anterior crural ; and internal to assist in the formation of the obturator. Its ter- minal branch is the anastomosing branch with the fifth, internal to the other two, and ver- tical in direction. The anterior branch of the fifth lumbar nerve is the largest of all the series, and terminates in the sacral plexus, and is named the lumbo- sacral nerve. The lumbar or lumbo-abdominal plexus is rather intricate, and formed by the anasto- mosis of the anterior branches of the five lumbar nerves. Placed upon the sides of the lumbar vertebrae between the transverse pro- cesses, and enveloped by the fasciculi of the psoas muscle, it presents, when the latter are dissected away from it, an irregularly triangu- lar appearance ; the apex of the triangle be- ing above, and the base below. In the former situation, the nerves forming it are compara- tively delicate, and unite with each nearer the vertebral column than the latter ; it com- municates above with the twelfth dorsal nerve, through the medium of the “ dorso-lumbar,” and below, with the sacral plexus, through the medium of the “ lumbo-sacral ” nerve. The branches given off from it may be divided into abdominal and crural : the former being given off from its upper ; the latter, from its inferior or terminal portion. The abdominal series is represented by the musculo-cutaneous nerves, and the genilo-crural. The crural series by the external cutaneous, crural, and obturator. The musculo-cutaneous nerves are two in number : the upper being three or four times larger than the lower. The upper musculo-cutaneous (large ab- dominal, llio-hypogastric, ilio-scrotal) is the highest of the branches of the lumbar plexus, taking its origin from the first lumbar nerve. It makes its appearance from behind the psoas muscle about an inch and a half below the last dorsal nerve, runs obliquely down- wards and outwards across the quadratus lumborum in the subperitoneal tissue, and about an inch above the crest of the ilium, perforates the tendon of the transversalis, and is continued between it and the internal ob- lique to the middle of the crest of the ilium, where it divides into two branches, an ex- ternal and internal. The external passes ob- liquely between the internal and external ob- lique, and at the anterior-third of the crest of the ilium, winding on to the glutseal re- gion, divides into an anterior and posterior series of filaments ; the one supplying the integument over the tensor vaginae femoris, the other that over the anterior part of the glutaeus medius. The internal branch, or the continuation of the nerve, after a course of an inch or two, communicates with the small musculo-cutaneous by a loop which usually passes round the internal circumflex ilii ves- sels. It then divides into an abdominal and scrotal branch. The abdominal runs parallel to the corresponding branch of the last dorsal, generally communicates with it, and passes through the tendons of the internal and ex- ternal oblique, and is distributed to the skin at the inner part of the groin. The inguinal. SPINAL NERVES. 7G2 jmbic, or scrotal branch runs parallel to Pou- part’s ligament, in company with, but above, the small external cutaneous, reaches the ex- ternal ring, and divides into internal terminal branches supplying the skin over the pubis ; and external ones supplying the scrotum in the male, and the labia pudendi in the female. The lower musculo-cutaneous (small muscu- lo-cutaneous — small inguino-cutaneous — small abdominal) is a thin delicate nerve, arising generally from the first lumbar, sometimes front the large musculo-cutaneous, is directed down- wards and slightly outwards, along the back part of the psoas, a little in front of the inner border of the quadratus lumborum, crosses the iliacus interims about its upper fourth, and reaches the anterior third of the crest of the ileum. There it is lost by communicating with the large musculo-cutaneous, or, as is generally the case, passes after this communication as a very delicate nerve between the internal ob- lique and transversalis, supplying the lower part of these muscles, but principally the latter, and parallel to Poupart’s ligament, per- forates the former muscle at the outer ring, and terminates in a manner similar to the pubic or scrotal branch of the upper mus- culo-cutaneous, in the scrotum and pubic in- tegument. The genito- crural nerve (external sper- matic — internal inguinal) derived from the second lumbar nerve, and sometimes from the communicating branch between the first and second, passes directly forwards to the anterior part of the psoas muscle, along which it de- scends vertically to the femoral arch. It lies behind the spermatic vessels, and is crossed by the ureter. Having reached Poupart’s ligament, it divides into two branches, an in- ternal or genital, and an external or crural. The genital is directed across the external iliac artery (to which it supplies a few filaments) to the chord, lying below it as far as the in- ternal ring. Prior to entering the inguinal canal the transversalis and internal oblique re- ceive a few reflected branches from it. The nerve then accompanies the chord, crosses the epigastric vessels, supplies the cremaster muscle, runs immediately in front of Gimber- nat’s ligament, and terminates in the scrotal integument in the male, anil labia pudendi in the female, supplying also the integument at the upper and inner part of the thigh, and communicating with the inferior pudendal nerve. The crural branch (femoral-cuta- neous), having given off several delicate fila- ments to be distributed to the transversalis and internal oblique, crosses the circumflex ilii vessels, passes underneath Poupart’s liga- ment, a little to the outside of the femoral artery, pierces the fascia immediately below the ligament, and becomes cutaneous, sup- plying the skin of the thigh at the middle part of its upper third. The division of the genito-crural into its terminal branches is subject to considerable variation, sometimes taking place either immediately after it has emerged from within the psoas, or within the psoas directly after its origin from the plexus. The crural division is at times also extremely small, the external cutaneous then having a more extensive distribution than ordinary. The external cutaneous (external inguinal) is a branch from the second or from the second and third lumbar, or is occasionally derived from the outer part of the crural nerve. It passes from beneath the outer border of the psoas below its middle, runs across the iliacus towards the space between the two spinous processes of the ilium, lying behind the transversalis fascia. It then passes beneath Poupart’s ligament, and divides into an interior and posterior branch. The poste- rior passes outwards and backwards over the fascia, covering the tensor vaginae femoris, and supplies the integument at the upper, outer, and back part of the thigh. The ex- tent of distribution of this branch is subject to variation, owing to the circumstance of a corresponding branch being occasionally sup- plied either by the great musculo-cutaneous, or by the genito crural, when the trunk of the external cutaneous itself comes from the anterior crural. In such instances this branch is small and insignificant, if it exist at all. The anterior branch becoming cutaneous about the upper fifth of the thigh, soon divides into an external and internal, directed downwards, over the fascia covering the anterior and outer part of the rectus muscle. The external di- vision terminates in the integument at the middle third of the outer part of the thigh ; the internal at the lower third of the thigh, above and to the outside of the patella. The crural nerve (femoral) is by far the largest branch of the lumbar plexus, and is placed in the substance of the psoas muscle between the external cutaneous, and the ob- turator, below the level of the former and above that of the latter, from which it diverges at an acute angle. It is formed by the union of the second with the outer branch of the third lumbar nerve, by part of the fourth, and generally by their communicating branch. It is destined to supply the integuments of the front of the thigh, and all the muscles at its anterior and outer portion. Having emerged from the psoas muscle it is directed forwards and outwards between that muscle and the iliacus to Poupart’s liga- ment, under which it passes, and entering the thigh becomes flattened and expanded, and divides into a series of divergent terminal branches, the trunk occasionally bifurcating before so doing. The nerve in its course within the pelvis is situated behind the iliac division of the trans- versalis fascia, external to the iliac artery, and gives off a few branches to the psoas and ili- acus. Outside the sheath of the femoral vein and artery it is separated from the latter by the intervention of the psoas muscle. The terminal branches may be divided into superficial and deep ; the first consisting of the internal , and middle cutaneous, and branches to the femoral vessels and pcctinceus : the second of branches to the quadriceps extensor cruris, and the cutaneous branch of the inner and SPINAL NERVES. 763 anterior part of the knee and leg, viz. the in- ternal saphcenus. The internal cutaneous nerve (internal mus- culocutaneous) directed along the inner bor- der of the sartorius muscle, perforates the fascia at the lower third of the leg, occa- sionally perforating the sartorius before so doing. Having given off several cutaneous branches, which form a connexion with the cu- taneous branch of the obturator in this situa- tion, it continues its course towards the lower and inner part of the thigh, having previously communicated with a branch perforating the sartorius, and coming from the internal sa- phasnus. From the thigh it passes along the inner edge of the patella, describing a curve, and sending some terminal filaments from its concavity upwards to unite with the middle cutaneous : others, from its convexity down- wards, to communicate with the reflected branch of the saphaenus itself, and also its accessory branch. The accessory saphcenus nerve (Cruveilhier) takes its origin from the internal cutaneous ; from the anterior crural in company with the latter ; or from the trunk of the saphaenus it- self. It soon divides into a superficial internal branch, which passes from within the sheath of the sartorius muscles over the femoral vessels, and adductor longus, and at the junc- tion of about the upper with the middle third of the thigh meets with the internal saphaena vein, which it accompanies as far as the knee- joint, in which situation it communicates with the internal saphaenus and cutaneous branch of the obturator. The external branch, situ- ated behind the level of the superficial, is directed inwards to the femoral artery, runs along its outer part in close contact with it, and accompanies the vessel in Hunter’s canal to its lower extremity. It then quits the artery, is directed in front of the tendon of the adductor magnus, to the upper part of the internal condyle of the femur, where it becomes cutaneous, anastomosing with the internal cutaneous above, with the reflected branch of the saphaenus below, and sending cutaneous branches over the inner and middle part of the patella. This branch has been termed by Cruveilhier the satellite nerve of the femoral artery : and the superficial branch might with equal propriety be denominated the satellite nerve of the saphcena vein. The accessory saphaenus is subject to considerable variation, both as to size and origin. The middle cutaneous nerve perforates the fascia three or four inches below Poupart’s ligament, crosses the sartorius muscle, and is directed over the inner part of the rectus to terminate in the cuticle over the front of the patella, anastomosing above with the external cutaneous nerve, and below with the internal cutaneous and accessory saphaenus. It fre- quently divides about the middle of the thigh into two branches, which run parallel with each other. The internal and middle cuta- neous nerves not unfrequently perforate the sartorius muscle before becoming cutaneous, the first at the middle, the second at its upper part. They are consequently described also as the inferior perforating cutaneous, and the superior perforating cutaneous. The nerve to the femoral vessels is very de- licate, and arises internal to the internal cu- taneous, sometimes however coming off from the lumbar plexus. It is directed downwards and inwards to the femoral vessels, and di- vides into a series of filaments, one or two of which are directed through the cribriform fascia to the saphaena vein, along which they pass in a tortuous manner till lost by com- municating with the internal branch of the accessory saphaenus, about the middle of the thigh. The remainder pass, some behind and some in front of the femoral vessels, and ter- minate at the lower third of the thigh, by uniting with the external branch of the acces- sory saphaenus. The branches to the pectinceus are directed inwards behind the femoral vessels, and in their course to this muscle generally send a few filaments to the psoas. The deep-seated muscular branches arise ex- ternal to the internal saphaenus nerve, and behind the superficial already described : and are from within outwards : Branches for the vastus interims and cruraeus : branch for the rectus : and branches for the vastus externus, which are the deepest of all. The branch for the vastus internus (short saphaenus), taking its origin in close contact with the internal saphaenus, from which it not unfrequently arises, is directed in com- pany with, but external to it, along with the femoral artery. It separates a little below the middle of the thigh from the vessels, and is directed to the external aspect of the vastus internus, to enter it at its lower one third ; but before so doing gives off a superficial ar- ticular branch, which passes in front of the outer border of Hunter’s canal ; in this situa- tion occasionally communicating either with the cutaneous branch of the obturator, or the outer branch of the accessory saphaenus; crosses through the superficial muscular fibres of the vastus to its aponeurotic termination, which it perforates, it is then reflected for- wards, upwards, and outwards, and terminates in two or three filaments, one of which passes behind the ligamentum patella, entering the anterior part of the knee-joint ; the others pass in front of the patella, to supply the periosteum and skin over it. The nerve for the crurceus, shorter than that for the vastus internus, enters the upper and inner part of the muscle, extends as far as its lower part, and gives off filaments to the deep-seated portion of the muscle (the sub- cruraeus) to the periosteum and upper part of the synovial capsule. The branch for the rectus enters the upper part of its posterior aspect, and divides into a superior branch which passes transversely out- wards, and a long vertical branch which passes along its inner side to the lower portion. The branch for the vastus externus frequently arising in company with that for the rectus, is directed downwards and outwards between 7G4 SPINAL NERVES. that muscle and the cruraeus, and, in company with the descending branches of the external circumflex artery, enters its inner aspect by two or three divisions, having previously given off a superficial articular branch. This filament, the analogue of the corresponding branch of the vastus interims, creeps beneath the su- perficial muscular fibres, and near the pa- tella becomes cutaneous, some of the ter- minal filaments passing behind the outer part of the ligamentum patella, others over the patella, where they are lost in the skin and periosteum. The sapheenus nerve (aacpris, manifest), the most internal of the deep-seated branches, and arising behind and external to the mid- dle cutaneous, is the largest branch of the crural. It passes downwards and outwards towards the femoral artery, and, about two or three inches below Poupart’s ligament, en- ters its sheath. The nerve first lies outside and behind the artery; but a little before the vessel enters Hunter’s canal it gets anterior to it. During the course of the artery down- wards and outwards, to enter the ham, the nerve inclines forwards and inwards, and quits the canal, in company with the anastomotic ar- tery, a little above the level at which the fe- moral vein and artery pass out. It now follows the course of the sartorius lying behind it, to the inner condyle, and one or two inches above the head of the tibia is placed between that muscle and the gracilis, and gives off, before continuing its course, the cutaneous tibial or re- fiected branch. This nerve first runs parallel for a short distance with the tendons of the two muscles, then sweeps downwards, for- wards, and slightly upwards over the fascia covering them and their tendinous expansions, and across the spine of the tibia to the skin at the upper and outer part of the leg, about two or three inches below the head of the tibia, communicating above with the internal cutaneous. The continuation of the nerve, or what may be termed the posterior trunk, inclines slightly backwards from between the tendon of the sartorius and gracilis, and on a level with the knee-joint is a little to the inner and back part of the tendon of the latter. Having received its connection with the cu- taneous branch of the obturator, it passes in company with the saphaena vein into the re- gion of the leg, inclining slightly forwards to the back part of the inner border of the tibia Having supplied the integuments at the upper, inner, and anterior part of the leg, it inclines slightly backwards about its middle, sends filaments to communicate with the continu- ation of the cutaneous branch of the obturator at the posterior part of the leg. It then again inclines forwards, and terminates about three or four inches above the ankle in two branches. The anterior terminal, the smaller of the two, supplies the skin at the lower sixth of the inner and front part of the leg, and over the front of the ankle joint, a few of the branches entering the articu- lation. The posterior terminal, apparently the continuation of the trunk, supply the inte- guments over the inner malleolus, upper, inner, and back part of the foot. The saphaenus nerve not unfrequently, in its course in the thigh, in company with the fe- mora! artery, gives off', at a variable height, usually however at the lower fourth of the leg, a small branch corresponding more or less with the distribution of the outer division of the accessory saphaenus. The internal sa- phaenus nerve first lies behind the correspond- ing vein ; then in front of it to the middle third of the leg, when it again is placed behind it : an inch or two before it divides into its ter- minal branches, it is again anterior to it, the latter passing over in front, and the other behind. The obturator nerve , derived from the third and fourth, and sometimes also from their internal intercommunicating branch, is much smaller than the anterior crural, and rounded. It perforates the inner border of the psoas, along which it is conducted to the pelvis, a little below the level of which it runs to between the external and internal iliac ves- sels. It then passes obliquely behind the ex- ternal iliac vein, crossing it at a very acute angle, and reaches the obturator foramen in company with, and above, the obturator artery. It passes through this foramen into the thigh, and terminates by dividing into super- ficial and deep) divergent muscular branches, situated behind the pectinaeus and adductor longus. 8oon after its origin a small nerve, the accessory obturator, is occasionally ob- served to proceed from the outer part of the trunk. It passes in company with the femo- ral vein, anterior and internal to it, beneath the femoral arch, over the horizontal ramus t f the pubis, and external to the pectinaeus. It is then directed a little inwards, and divides into several branches, some of which enter the joint through the anterior part of the cap- sular ligament ; others supply the posterior surface of the pectinaeus, and the remainder, as the continuation of the nerve, terminate by communicating either with the upper part of the trunk of the obdurator itself, or with the branch of the nerve destined for the adductor longus. The obturator nerve, in passing through the subpubic canal, gives off two or three branches to the obturator externus muscle : one pene- trating its upper edge, the others its anterior surface. Some articular filaments are also sent off in this direction, and accompany some of the branches of the inferior division of the obturator artery, beneath the trans- verse ligament to the hip-joint. The relation of these filaments as to size anil numbers, how- ever, is not constant, being in the inverse pro- portion to the size and number of branches given off from the accessory obturator, which is not unfrequently absent. From the superficial branch is given off a long filament internally to the gracilis muscle, which runs for about two inches along the outer surface of the muscle before entering it, another to the posterior surface of the pec- SPINAL NERVES. 7Gj tinaeus, which varies in its size according to whether this muscle be supplied by the ac- cessory obturator or not : and a third to the adductor longus, which also enters its posterior surface. The most important branch, however, is the long cutaneous branch which emerges from behind the lower border of the adductor lon- gus muscle, passes in the fascia behind the internal saphmna vein as far as the knee joint, where it perforates the fascia, and becomes cutaneous at the anterior border of the tendon of the gracilis muscle. In this part of its course, a little below the upper third of the thigh, it communicates either with the internal branch of the accessory saphcenus, or with a branch occasionally given off from the saphte- nus itself, and which accompanies the saphaena vein to the knee joint. It gives off cutaneous branches to the middle of the thigh, forming, with the above nerve, a more or less intricate plexus. Having perforated the fascia on a level with the knee joint, above it, or a little below it, it communicates with the trunk of the internal saphmnus (being occasionally only in apposition with it), and internal cuta- neous nerve. It terminates by being directed downwards and backwards to above the lower part of the poplitaeal region, and continues to give off cutaneous branches, till it is lost in the integument at the inner and back part of the leg to within two or three inches of the ankle : having previously sent filaments of communication to the continuation of the saphaenus nerve. The deep branch of the obturator runs gene- rally behind the adductor brevis, and divides into two branches, one ramifying through the centre of that muscle : the other, for the supply of the adductor magnus. From the latter is given off a small articular nerve for the knee joint, which is directed downwards and out- wards, towards the attachment of the adductor magnus to the linea aspera, perforates this attachment below the middle of the thigh, and is directed with the poplitmal artery into the ham, winding around the artery, and giving off an internal delicate branch, which enters the knee joint through the ligament of Winslow. The Anterior Branches of the Sacral PTei ves are six in number, and escape from the anterior sacral foramina, decreasing in size from above downwards, and presenting, consequently, cha- racters reverse to what obtain in the corre- sponding branches of the lumbar nerves. They communicate with the sacral ganglia of the symphathetic, the filaments of communication being usually two between each nerve and the sympathetic. The first nerve, smaller than the lumbo- sacral nerve, extends more obliquely down- wards and outwards, and having passed from the first sacral foramen, unites with it at an acute angle, and communicates with the second nerve. The second nerve, somewhat smaller than the first, passes more obliquely downwards and outwards from the second anterior sacral foramen, and, having communicated with the third, enters the sacral plexus, sometimes bifurcating previously. The third nerve, about one-third the size of the second, comes from the third sacral fora- men, and passes more horizontally outwards to the sacral plexus, having communicated with the second by a delicate filament sent in front of a portion of the pyriformis intervening between it and the second nerve. The fourth verve, considerably smaller than the third, passes from the fourth sacral fora- men, communicates above and below with the third and fifth nerve, and terminates in three sets of filaments. One, usually in the form of a single trunk, is directed a little downwards and outwards, between the levator ani and the coccygaeus muscle, gives branches to them, and finally becomes cutaneous. This filament in its course generally furnishes a small twig which perforates the great sacro-sciatic liga- ment, and terminates in the skin over the border of the coccyx. A second, as a single small trunk, passes to enter the sacral plexus. The third series anastomose freely with the hypogastric plexus, and then form of them- selves a loose kind of interlacement, from which branches are given off to the rectum sides of the bladder, prostate, and vesiculm seminales, and the vagina in the female. The levator ani generally receives one or two fila- ments, a distinct twig entering the middle, the other supplying the anterior part, after rami- fying on the prostate. The fifth passes front the fifth anterior sacral foramen, communicates above and below with the fourth and sixth, and sends a filament which perforates the coccygaeus muscle, sup- plies it, and terminates on the skin to the side of it. The sixth (anterior branch of the coccygaeal nerve) is extremely delicate, passing between the lower cornu of the sacrum, and the upper border of the coccyx, communicates within the bone with the descending branch of the fifth, and terminates by passing along the border of the coccyx in the substance of the sacro-sciatic ligament to become cutaneous. Some filaments are given off from it which supply the coccygaeus ; others perforate the ligament, and are lost in the substance of the glutaeus maximus. The Sacral Plexus (sciatic) is formed by the lumbo-sacral nerve and the four upper ante- rior branches of the sacral nerves, principally, however, by the convergence of the three upper: the fourth sacral nerve sending merely' a small filament of communication. The branches that contribute to its formation enter it at once, at a more or less acute angle, with- out any complex subdivision, as usually occurs in other plexuses. It has a well marked tri- angular figure, the apex being indicated by the line of convergence of the different trunks : the base by the trunks as they issue from the sacral foramina. It rests upon the pyriformis muscle, the internal iliac vessels separating it from the pelvic viscera, being however in im- mediate relation with a layer of pelvic fascia. Before terminating in the great sciatic nerve. 7GG SPINAL NERVES. the plexus gives off a series of anterior and posterior branches. Of the former are ob- served, a nerve for the obturator internus, and the internal pudic : of the latter, the su- perior glut seal, inferior glutaeal, nerves for the pyriformis, gemelli, and quadratus femoris. The nerve for the obturator internus takes its origin from the upper and outer part of the plexus, being derived from the lumbo-sacral and first sacral. It passes behind the spine of the ischium, and the lesser sacro-sciatic liga- ment, reenters the pelvis at the lesser sciatic notch, and is distributed by three or four branches within the inner aspect of the muscle. The internal pudic nerve, arising from the lower part of the plexus, and generally de- rived from the third and fourth nerves, passes behind the spine of the ischium, internal to the pudic artery, in company with the preceding, and then enters the ischio-rectal fossa, where it divides into a superior and inferior branch. The superior branch (the dorsul nerve of the penis ) ascends in company with the internal pudic artery, but above it, between the obtu- rator internus and the levator ani, to pass between the two layers of the triangular liga- ment: perforating the anterior layer imme- diately under the pubic arch it gains the dor- sum of the penis, in which situation it is placed in the fold of the suspensary ligament, and in- clines inwards to the median line. Having given off one or more external branches, which run superficially as long and slender fila- ments along the upper and outer part of the penis, supply the corpora cavernosa and their integument, and are conducted as far as the prepuce, the nerve continues its forward direc- tion. It passes to the side of the median line, sends numerous filaments to the skin ; commu- nicating branches to the nerve of the opposite side; and some to accompany the dorsal vein of the penis; and at the root of the glans penis, penetrates deeply between it and the corpus cavernosum,and terminates by sending numer- ous filaments throughout its substance. The inferior branch (Perinaeal nerve — su- perficial peri meal) perforates the obturator fascia at the inner and anterior part of the tuberosity of the ischium, and divides into two branches, an anterior and superior, having previously given off a posterior branch, named by Cruveilhier the external perinceal, which passes through the obturator fascia behind the tuberosity of the ischium. It runs in company with, but external to, the anterior branch, superficial to the crus of the penis, and terminates by supplying the lower and anterior part of the scrotum where it gives off filaments on the inside to unite with some from the anterior branch, on the outside to communicate with the long inferior puden- dal branch of the lesser sciatic. The an- terior branch passes in the interval between the accelerator urinae and the erector penis, internal to the preceding, and inclines a little forwards and inwards, and ends in a series of long filaments, which communicate laterally with the external perinaeal, and send branches to the middle of the lower and anterior part of the skin of the scrotum, some of them being conducted along the skin at the lower aspect of the penis as far as the prepuce. The su- perior branch soon divides into a series of muscular branches, after having passed above the transversalis perinaei muscle. Some are sent inwards to the external sphincter, le- vator ani, and accelerator urinae : others to the erector penis ; the termination of the nerve being represented by a small branch, which passes into the substance of the bulbous por- tion of the urethra. The pudic nerve not unfrequeritly gives off the inferior hcemorrhoidal (anal), which passes j along its inner side, is directed through the obturator fascia to the ischio-rectal space which it traverses to the side of the rectum, and at the upper border of the external sphincter divides into a series of filaments, the anterior of which communicate with the superior branch of the perinaeal, and supply the front of the sphincter and the skin over it. The middle and posterior series supply the sides and back part of the sphincter. Some filaments are given off externally, which pass over the great trochanter, and communicate with the long inferior pudendal nerve. The skin about the anus is also freely supplied. The inferior haemorrhoidal, when not a branch of the pudic, is given off from the sacral plexus. The superior glutccal nerve is derived either from the lumbo-sacral nerve only, or from two distinct roots, the one from it and the other from the back part of the first sacral nerve. The former source of origin usually obtains ; and in the latter the root from the sacral nerve is not more than half as long as that from the lumbo-sacral. It passes out as a single trunk at the upper and fore part of the border of the sacro-sciatic notch, in front, and above the pyriformis, and divides into a superior and inferior branch. The superior branch takes the course of the superficial trunk of the corresponding artery, courses along the convex border of the glutaeus minimus, and supplies principally the upper and back part of the glutaeus mo- dius. The inferior branch is directed down- wards, forwards, and outwards between the two glutsei, and, after a short course, divides into a superficial branch, supplying the upper and anterior part of the glutaeus medius ; and a deep branch running across the glutaeus minimus, supplying it and the medius, and terminating near the great trochanter, by entering the substance of the tensor vagime femoris, at the lower, inner, and back part of its sheath. The inferior glutaeal nerve (lesser sciatic) arises from the back part of the sacral plexus by one or more roots. It emerges from the pelvis at the lower and anterior part of the great sacro-sciatic notch, either as a single, or as two, or three, trunks, below the pyri- formis, and about a quarter of an inch behind and internal to the great sciatic. It is directed between the tuberosity of the ischium, and the great trochanter, but nearer the former. SPINAL NERVES. over the back and inner part of the gemelli, and divides into muscular and cutaneous branches. The muscular branches are long and numerous, being destined to supply the glu- taeus maximus. One series are directed out- wards, upwards, and forwards, and, entering its anterior surface, ramify through the sub- stance of the muscle, as far as its upper and anterior part. The other series are directed downwards, backwards, and outwards, over the tuberosity of the ischium, and supply the lower and back part of the muscle. The inferior glutaeal having emerged from beneath the lower border of the glutaeus maximus, divides into its two terminal branches, perinaeal cutaneous, and cutaneous branch to the thigh and upper part of the leg. The peri- nceal cutaneous nerve is reflected upon the lower border of the glutaeus maximus, and describes a curve, the concavity of which looks towards the sacrum. It soon divides into an external large branch, supplying the skin in the glutaeal region, and an internal small branch (the long inferior pudendal of Soemmering), which passes in a curved man- ner beneath the tuberosity of the ischium. It is then directed beneath the fascia of the upper and inner part of the thigh, running parallel to the ascending ramus of the ischium, and at or near the junction of the latter with the descending ramus of the pubis, perforates the fascia, and becomes cutaneous, supplying the skin in the perinaeum ; it anastomoses either with the superficial perinaeal, or the external perinaeal nerve, and sends terminal branches to supply the inner and outer por- tions of the scrotum, and the lower part of the skin of the penis. The cutaneous branch to the bach of the thigh and upper part of the leg. — The continuation of the trunk of the inferior glutaeal is situated anterior and external to the above-named branches. It passes obliquely over the inner and back part of the biceps muscles, and, a little above the middle of the thigh, ordinarily divides into two branches. The small external branch passes downwards, forwards, and out- wards to the upper part of the lower third of the thigh, in which situation it anastomoses with the external cutaneous nerve of the lumbar plexus. The large internal branch runs down a little to the inside of the median line of the thigh to the skin in the poplitaeal region, where it divides into external terminal filaments, supplying the skin over the outer and back part of the tibia and fibula, and in- ternal filaments, some of which go to the skin at the inner part of the poplitaeal region, others very small, accompanying and surround- ing the external saphaena vein, communicate below the middle of the leg with filaments given off from the external saphaenus nerve. The nerve for the pyriformis passes below the level of the superior glutaeal nerve, from the middle of the back part of the plexus, generally taking its origin from the third sa- cral nerve. It is distributed to the anterior surface of the muscle. The nerves for the gemelli and quadratus fc- 767 moris pass from the plexus along the lower part of the pyriformis, close to the os inno- minatum, to the anterior surface of the muscles. That for the quadratus femoris gives off a few branches to the capsular ligament, one of which enters the articulation, and usually sends off the nerve which supplies the inferior gemellus. This nerve comes off frequently from the upper part of the great sciatic. The great sciatic nerve (the sciatic, ischi- atic, femoro-poplitaeal), the largest nerve in the body, is formed by the convergence of a branch of the fourth lumbar, the lumbo-sa- cral, and the three or four upper sacral nerves ; represents the termination of the sa- cral plexus, and is destined to supply the muscles at the back part of the thigh, and the muscles and integuments of the leg and foot. It escapes from the pelvis, from beneath the lower border of the pyriformis, as a flattened ribbon-shaped nerve, about half an inch broad, soon becomes rounded, and continuing its course from between the great trochanter and tuberosity of the ischium, descends with a slight inclination outwards to the back part of the thigh, a little to the outside of the me- dian line, as far as, or somewhat above, the level of the upper angle of the poplitaeal space, where it divides into terminal branches, the peronaeal and posterior tibial. This division occasionally takes place within the pelvis, in which instances the outer division passes either between the lower fascicles of the pyriformis or above the muscle, the inner beneath the lower edge of the muscle. In some instances it takes place while the nerve is placed between the trochanter and tube- rosity: in others, again, the two trunks are dis- tinct as far as this situation, where they again unite, and subsequently divide in the poplitaeal space. In the upper part of its course the nerve is rather deeply seated, being covered over by the glutaeus maximus, and having be- hind and internal to it the branches of the inferior glutaeal nerve. At the lower border of the tendon of the glutaeus maximus it is crossed by the long head of the biceps, and in the remainder of its course is covered only by the fascia. It is in relation in front with the two ge- melli and obturator internus, the quadratus femoris and adductor magnus. Behind these muscles it passes successively from above downwards, is in close contact with the su- perior, and separated from the adductor magnus by a quantity of fat and cellular membrane. The branches given off from the sciatic nerve are muscular and articular. The muscular branches come away above the middle of the thigh, with the occasional ex- ception of that for the short head of the biceps, which arises near the middle. There are several branches for the long head of the biceps, some of which ascend to be dis- tributed to the muscle at its origin; others descend for some distance, and enter its an- terior surface. The nerve for the semi-tendinous is a long delicate filament, which usually passes down 7C8 SPINAL NERVES. to the lower third of the thigh before it enters its surface. The senii-membranosus generally receives two or more branches: and from the lower is not unfrequently derived a branch for the ad- ductor magnus, which also receives a branch from the main trunk. The articular nerve is usually given about the middle; but as this nerve, in the majority of instances, is derived from the peronaeal, it will lie described with that nerve. The peronaeal nerve (external poplitaeal — external poplitaeal-sciatic) is more superficial, and not much more than a third the size of the posterior tibial. It is directed down- wards and outwards along the inner edge of the biceps muscle, behind the outer condyle of the femur, the outer head of the gas- trocnemius, and the outer and back part of the head of the tibia, to below the head of the fibula, where it divides into four branches, the anterior tibial , and musculo-cutaneous, the former being larger than the latter. The peronaeal nerve, during this course, gives off superficial cutaneous branches , and occasionally deep articular: the former being represented by the peronaeal cutaneous and peronaeal saphaenus, the latter by the superior and inferior external articular. The peronaeal cutaneous proceeds from the back part of the nerve, generally an inch or two alter its commencement. Having passed superficially with the trunk as far as its ter- mination, and having supplied the integu- ments in its course, it gives branches on the one hand to the integuments immediately on the outside of the external saphaenus, and on the other over the upper part of the pero- nasus longus, the middle terminal filaments extending below the middle of the leg, and communicating with cutaneous branches from the external saphaenus. The peronaeal sapheenus (communicans fibu- lae— communicating saphaenus) usually taking its origin above and to the inside of the pe- ronaeal cutaneous, is directed downwards and inwards beneath the skin, and communicates with a corresponding branch from the pos- terior tibial to form the external saphaenus. This communication is very variable as to situ- ation, usually taking place below the middle of the leg, where it perforates the fascia, oc- casional!}', however, in the lower part of the poplitaeal space in front of the fascia. The nerve now and then runs quite distinct from its corresponding branch, which consequently in these instances entirely constitutes the external saphaenus. It is either very small, terminating about the middle of the leg, or divides opposite the lower part of the tendo Achillis into branches which pass over the lower part of the peronaeus longus to the skin of the external malleolus, where they communicate with small descending branches from the musculo-cutaneous ; and into those which supply the skin at the lower and outer part of the heel, communicating in the in- terval between the heel and malleolus with branches from the external saphaenus. The deep articular branches are external and internal, the one arising above the other. They are thus described by Mr. Ellis*: — “ The superior external articular nerve, arising either from the trunk of the sciatic or the externa! poplitaeal in the case of a high divi- sion of the sciatic, is a long slender nerve, which descends deeply into the poplitaeal space, under cover of the biceps muscle, nearly as low as to the outer condyle, then passes from the space beneath the tendon of the biceps, reaches the superior articular artery, which it accompanies to the front of the joint, and supplies the synovial membrane of the articulation. The inferior external articular, more fre- quently a branch of the external poplitaeal than of the sciatic, is also a long nerve close to the biceps, and has the same direction as the preceding ; but it extends lower down, passing beneath the tendon of the biceps, and below the condyle of the femur, to the artery of the same name, and it divides on the outer side of the articulation into many branches that extend forwards, perforate the capsules, and supply the synovial membrane. The anterior tibial nerve (interosseous nerve), rather larger than the musculo-cuta- neous, passes from beneath the extensor com- munis digitorum, having previously perforated the deep surface of the peronaeus longus, to the interosseous membrane, which it crosses obliquely downwards, forwards, and inwards ; and a little below the middle of the leg is placed in front of the corresponding artery. It continues to accompany the vessel beneath the annular ligament, passing first to the in- side of it, then to the outside, and again to its inside, while behind the annular ligament it divides into an internal and external terminal branch. The nerve in this course is placed first between the tibialis anticus and extensor communis digitorum ; then between the former and the extensor proprius pollicis, and lastly between the extensor pollicis and the extensor communis digitorum. In its course from the leg to the ankle the anterior tibial gives off branches to the different muscles between which it passes ; and also one or two delicate satellite filaments to the anterior tibial ves- sels. The terminal branches are both rather deeply seated. The internal deep branch, the continuation of the trunk in reference to di- rection, but not to size, being smaller than the external, passes beneath the dorsal artery of the foot and the tendon of the extensor brevis destined for the great toe, gives fila- ments to supply the inner part of this muscle, and reaches the first interosseous space, send- ing a few twigs to the first interosseous muscle. At the anterior part of this space it communi- cates with the musculo-cutaneous, and ter- minates by dividing into two branches destined for the opposed sides of the first and second toes. The external deep branch passes obliquely * Ellis’s Demonstrations of Anatomy, p. 675. SPINAL NERVES. outwards beneath the exterior brevis, supplies this muscle, and gives off from its anterior part several delicate filaments, which running close to the tarsus reach the three outer interosseous spaces, and expand in the sub- stance of the interosseous muscles. The musculo-eutaneous nerve (the external peronaeal), commencing its course below and behind the anterior tibial, and running more superficial and external than it, is directed, first obliquely then vertically downwards in the substance of the peronaeus longus ; it is then situated behind the fascia, and at a vari- able distance from the ankle, generally at the lower third, perforates the fascia, between the extensor communis, and peronaeus tertius. Subcutaneous in the remainder of its extent, it follows the course of the extensor com- munis, and after running for a greater or less distance parallel to it, divides into an internal and external branch which diverge consider- ably from each other. This bifurcation is sub- ject to variation, taking place sometimes while the nerve is situated behind the fascia, at others over or very near the annular liga- ment, and occasionally the two divisions re- unite over the annular ligament, and form an irregular oval space between them. While passing deeply between the muscles of the leg this nerve sends two filaments to the peronaeus longus, the inferior of which, given off about the upper fourth of the leg, can be traced running in the subtance of the muscle, to within two or three inches of the ankle. The upper part of the peronaeus brevis also receives a small branch. Shortly after perforating the fascia, the musculo-eutaneous sends off' its malleolar branches directed down- wards and outwards to the skin over the outer ankle, and anastomosing with cutaneous branches either from the external saphaenus, or the termination of the peronaeal cutaneous. The internal terminal branch, passing over the annular ligament giving a few branches to it, and some to communicate with the internal saphsenus and anterior tibial, is di- rected along the inner border of the foot to the inside of the great toe as far as its ex- tremity. The external branch, having passed over the annular ligament, divides into three branches which are directed along the three outer interosseous spaces, and near their an- terior extremities, each branch again sub- divides into two filaments supplying the op- posed sides of the four outer toes, the most external filament anastomosing with the ex- ternal saphtenus. Both terminal branches, in their course from the annular ligament to the toes, send off numerous filaments to the skin on the dorsum of the foot. Such is the usual distribution of the musculo-eutaneous nerve ; but frequently the outer branch does not sup- ply the inner side of the little toe, and occa- sionally gives filaments only to the opposed sides of the second and third toes. In these instances an extension of the external sa- phaenus nerves compensates for the deficiency. The tibial nerve (tibial-sciatic, internal po- plitaeal) much larger than the peronaeal or 7C9 external poplitaeal, is in a direct line with the sciatic nerve. It passes through the centre of the poplitaeal space, rather nearer the semi- membranous than the biceps, then between the two heads of the gastrocnemius to the lower border of the poplitaeus. It perforates the tendinous arch of the solaeus, reaches the front of that muscle, and passes down the leg between it on the one hand and the deep- seated muscles on the other. At the lower third of the leg it runs from beneath the inner border of the solaeus, and continues its ter- minal superficial course, anterior and internal to the tendo Achillis, as far as the lower extre- mity of the tibia, and, on a level with the base of the external malleolus, divides into the internal and external plantar. In the upper part of the poplitaeal span, the tibial nerve is superficial and external to the po- plitaeal vessels in the middle immediately be- hind, and at the lower part is placed internal to them. This last relation the nerve holds as far as the lower third of the leg, when it crosses the posterior tibial artery ajain to its outer side. It continues very gradually to separate from the vessel ; so that in the in- terval between the heel and malleolus the nerve is a quarter of an inch nearer the os calcis than the vessel. The branches given off from the tibial are muscular, articular, and cutaneous. The majority of the muscular branches arise from the posterior part of the trunk, and we observe, first, two branches for the two heads of the gastrocnemius entering their an- terior surface. The inner branch arises fre- quently from a trunk common to it and the tibial saphaenus ; the outer, from a trunk com- mon to it and a large branch for the solaeus, which enters, usually, the posterior surface of that muscle. When the outer branch is small, one or two others are given off lower down, to enter its anterior aspect. The small branch for the plantaris is derived, in the majority of in- stances, from the trunk of the tibial ; but sometimes from the inferior internal articular nerve. The nerve for the poplitceus, given off op- posite the knee-joint, is directed forwards to the poplitaeal vessels, descends external to them, and terminates at the lower border of the muscle by entering its substance. The nerve to the tibialis posticus comes off from the above, descends along the back of the muscle, gives numerous filaments to it, and terminates by entering below the middle. The nerve for the flexor communis digitorum and the longus pollicis take their origin together somewhat below the preceding ; that for the latter muscle being the larger, and descend- ing to within a short distance of the ankle joint, in company with the fibular artery. The articular branches are three in number, and correspond with the internal and anterior articular branches of the poplitaeal artery. “ The superior internal articular, very small, arises above the articulation, descends on the outer side of the poplitaeal vessels, passes beneath them, and runs with its artery to the 3 D 770 SPINAL NERVES. front of the femur and inner part of the ar- ticulation ; this is the least constant of the branches. The inferior internal articular , the largest of the nerves to the joint, arises rather above the articulation, descends to it, lying external to the vessels, is then directed in- wards, beneath the poplitaeal vessels, and meets with the artery of the same name ; it now lies on the poplitseus, covered by the fascia, passes beneath the internal lateral liga- ment, winds round the head of the tibia, per- forates the capsule, and supplies the synovial membrane. This branch gives, occasionally, some filaments to the posterior part of the articulation. The last articular branch is the posterior or azygos, which is given off opposite the joint, or from the inferior internal nerve : it perforates the posterior ligament, and is distributed to the articulation.”* We have observed this inferior articular nerve give off, occasionally, muscular filaments to the plan- taris, and upper part of the poplitaeus. The cutaneous branch is named the tibial sa- phcenus (external saphaenus — communicating saphaenus — communicans tibiae), and takes its origin from the back part of the trunk ex- ternal to the muscular branches. It inclines a little to the outside of the middle of the poplitaeal space, under the fascia, but super- ficial to the gastrocnemius, along the posterior surface of which it passes till it perforates the fascia at a variable distance from the ankle, and receives the corresponding branch from the peronaeal saphaenus. It is then directed, under the name of the external saphcenus, along the outer part of the tendo Achillis to the outer and back part of the external ankle, where it divides into its terminal branches. In the first part of its course it lies to the inside of the external saphaena vein. Near the lower angle of the poplitaeal span it passes in front of the vein to get to its outside, continues external to it as far as about an inch above the outer ankle, and again passes in front of it to its inside. The tibial saphaenus gives off no branch till it becomes external saphaenus, and internal and external cutaneous branches arise from it. The internal supply the outer and back part of the leg : and a superior and inferior calcaneal branch are generally observed. The superior is directed over the tendo Achillis, supplies the skin at the inner and back part of the heel, and communicates with filaments from the external plantar : the inferior passes along the outer border of the tendo Achillis to the skin at the outer and lower part of the heel. The outer cutaneous run downwards and forwards over the tendon of the pero- naeus longus, as far as the malleolus externus, communicating above with descending fila- ments of the peronaeal cutaneous ; and below with the malleolar filaments of the musculo cutaneous. Independent of these, cutaneous filaments and a few delicate nerves are given off, which accompany the saphaena vein. The terminal branches are composed of a se- ries of cutaneous branches to the back part of * Ellis’s Demonstrations of Anatomy, p. 676. the ankle, heel, and back part of the outer edge of the foot, and a long nerve, the continuation of the trunk directed along the outer edge of the foot to supply the outer margin of the little toe, communicating previously with the musculo-cutaneons. ] The termination of the tibial saphaenus nerve is subject to considerable variation, both as to size and distribution. It occasionally forms no connection with the peronaeal saphaenus, and then is very large. When united with the peronaeal saphaenus, so as to form the ex- ternal saphaenus, its terminal branch not un- frequently divides into two ; the one division for the opposed edges of the fourth and fifth toe ; the other for the outer edge of the latter, i We have observed the saphaenus nerve sup- plying also the opposed edges of the third and fourth toes, whilst the museulo-eutaneous in this instance supplied merely the inner edge of the great toe and the opposed margins of the second and third toes. The tibial nerve, before dividing into the in- ternal and external plantar, gives off, a little ] above the ankle, an interned calcaneal branch, which in a high division of the nerve conies 1 away from the external plantar. Having sup- plied the skin at the inner aspect of the heel, ] it winds beneath the inferior surface of the os calcis, and communicates with the calcaneous I] branch of the external saphaenus. The internal plantar nerve, larger than the external and analogous to the median nerve]] in the hand, passes behind the internal malleolus Jj superficial to and distinct from the tendons of] the tibialis posticus, and in front of the pos- terior tibial vessels. It then runs above]! the abductor pollicis, and is directed in the intermuscular septum, between it and the flexor brevis digitorum. Having perforated this, it appears between the two muscles, and ; divides into internal and external branches The internal branch is smaller than the ex- ternal, passes from without inwards over the tendon of the long flexor of the toe to the inner side of the metatarsal bone, gives fila- ments to the abductor pollicis, flexor brevis, and the skin, and terminates at the inner side of the toe, supplying in its course filaments to the articulations, and when it reaches the last phalanx, a small cutaneous branch to the dorsum. The external branch divides after a course of about an inch or two. The internal division, as it is directed along the first interosseous space, gives off in its course filaments to the first interosseous and lumbricalis, and at the anterior part of this space divides into two twigs for the opposed sides of the great and second toe. The external division, after a very short course, divides into two branches : the internal crosses obliquely the second in- terosseous space, gives filaments to the second lumbricalis, and bifurcates at its anterior ex- tremity for the supply of the opposed sides of the second and third toes : the external crosses obliquely to the third interosseous space, and like the preceding divides at its anterior extremity into two twigs for the SPLEEN. 771 ipposed sides of the third and ourth toes, laving previously communicated with the ex- ernal plantar. These different divisions of the internal lantar nerve give off', in their course, fila- nents to those portions of the cuticle with vhich they are in relation ; and also small wigs for the metatarso-phalangeal and pha- angeal articulations, and muscular branches o the flexor digitorum brevis, over the ten- ions of which the different divisions of the xternal portion of the nerve are obliquely ,nd superficially directed. The external plantar nerve, smaller than he internal, is directed forwards and out- vards between the musculus accessorius and lexor digitorum brevis, giving filaments to •ither, and, having reached the inner border of lie abductor minimi digiti, which muscle it sup- ilies, divides into a deep and superficial branch. The deep branch passes from between the irst and second layer of muscles to place it- :elf between the latter and the third, passing n company with the exterual plantar artery. It describes a curve, the concavity of which ooks towards the heel and inner malleolus. Filaments are sent off for the two outer lum- iricales, for the transversalis pedis, the ad- luctor pollicis, the interossei, and the tarsal md metatarsal articulations. The superficial branch passes obliquely for- wards and outwards between the flexor brevis digitorum and abductor minimi digiti, to both af which it gives filaments, and soon divides into an external and internal branch. The external branch reaches the outer border of the foot, and terminates at the extremity of the outer aspect of the little toe; giving filaments to the flexor brevis minimi digiti and the articulations. The internal, larger, com- municates with the most external division of the internal plantar, and bifurcates at the ex- tremity of the fourth interosseous space, for the supply of the contiguous sides of the fourth and fifth toes. The divisions of the superficial branch of the external plantar nerve, like those of the internal, supply the portions of the integument with which they are in relation, as also the articulations over which they pass. The internal and external plantar nerves are, in reference to size, directly the reverse of the corresponding, arteries : the former giving off seven filaments for the supply of the three inner toes, and half of the fourth ; and being analogous in its distribution to the median in the hand : the latter giving oft' only three filaments for the fifth and half of the fourth toe, and corresponding with the distri- bution of the termination of the ulnar nerve. ( Nathaniel Ward.) SPLEEN. ( Lien seu Splen, Lat. ; jv, Gr. ; die Milz, Germ.; la Rate, Fr.) Nor- mal anatomy. The spleen is a single so-called “ vascular gland,” which is attached to the cardiac extremity of the stomach, and appears to possess some intimate connection with the renovation of the blood. Situation and form. — The spleen has a roundish elongated form, or almost the shape of half an egg, and lies in the left hypochon- driac region. We recognise on it two sur- faces, two borders, and two extremities. The outer surface (superficies externa seu convexa ) is completely free and smooth, and often ex- hibits a more or less deep, long, and oblique incision : it looks outwards, upwards, and back- wards ; and is in contact with the left costal portion of the diaphragm, corresponding to the tenth and eleventh ribs. The inner surface (superficies interna seu concava ) is directed inwards and forwards; is for the most part slightly concave, and presents, in a prolonged elevation which occupies its middle, a vertical furrow, the fissure for the vessels, or hilus lienalis, which contains many holes and de- pressions, through which pass the nerves and vessels to and from the spleen. This fissure separates the concave surface into an anterior and larger, and a posterior and smaller por- tion ; and it is connected by the broad, but short gastro-splenic omentum ( ligamentum gastro-lienale ), with the fundus of the stomach, to which the remainder of the concave surface is opposed. The upper • extremity or head of the spleen (caput Hems'), is the thicker and more obtuse of the two ; it occupies the ele- vated hinder part of the eighth rib, and is con- nected by a suspensory ligament (ligamentum phrenico-lienale sen suspensiorum) with the diaphragm. The lower extremity or cauda lienis, is thinner and more pointed, and is directed downwards and forwards. The i in- terior border ( margo anterior) is the thinner and sharper, and is free. The posterior border (margo obtusus) is thick and rounded, and is in contact with the lumbar portion of the diaphragm, and the anterior surface of the left suprarenal capsule. The spleen is thus least moveable, where it is limited by the diaphragm ; but much more so at the site of its attach- ment to the stomach. But its situation changes with the variable positions of the diaphragm and stomach : thus, on the one hand, it de- scends and rises in the states of in- and ex- spiration respectively ; and, on the other hand, becomes more superficial or deeper, according as the stomach is empty or full. Varieties of the spleen. — It is not un- common to find the anterior border of the spleen, presenting one or more separate deep fissures. Also supplementary spleens (lienculi, seu lienes succenturiati ) are now and then ob- served : according to Rosenmiiller and Giesker, more frequently in the Southern than in the Northern Germans. These are situated in the gastrosplenic ligament, and rarely in the great omentum (Morgagni, Huschke) ; they are red, of the ordinary splenic structure, and of a size which varies from a linseed to a walnut. They are generally one or two in number, less frequently four or seven, and in a misdeveloped foetus have even amounted to twenty-three. The size and weight of the spleen experience great variation, not only in different indi- viduals. but even in one and the same person : 3 r> 2 SPLEEN. 772 of this more will be said hereafter. On an average, its length is from 4 to 5| inches * ; its thickness from 1 to 1J- inches ; and its breadth, from the anterior to the posterior border, 3 to 4 inches. According to Krause, its cubic contents range between 9J and 15 inches, with an average of 12. Its absolute weight varies from 6 to 15 oz., according to Soemmering ; from 7J to 10|, according to Krause ; and it has a medium of about 8 oz. According to J. Reid between the twentieth and sixtieth years, it ranges from 6 to 10 oz. in the male, and from 3 oz. 1 3^ dr. to 9 oz. 10 dr. in the female. Krause also states, that its specific gravity varies from 1.0579 to 1.0625, with an average of 1.0606. The consistence of the spleen is not very great : its parenchyma is soft and doughy, readily yielding to the pressure of the finger. It is not unfrequently torn by mechanical injury during life ; indeed, more easily than any other glandular organ, especially if it be over-distended with blood at the time; but, under the opposite circumstances, it is much less disposed to give way. The colour of the spleen is bluish red, during life greyish violet, and the parenchyma is of a dark dusky red. Structure. — In the spleen we first distin- guish the coverings or involucra, and the paren- chyma or proper spleen-substance. The first consists of the serous and the fibrous mem- brane. The latter is composed of a frame- work of reticulated fibres firmly connected together, constituting the so-called trabecular tissue (trabeculce Hems') ; and, beside this, of the red spleen-substance, the splenic cor- puscles, and vessels and nerves, together with sheaths which arise from the fibrous coat. 1. The serous membrane ( tunica serosa) is a part of the peritoneum. It accurately covers the outer surface of the spleen as a smooth membrane, with the exception of its hilus only, where it takes the form of two folds which convey the vessels of the organ, con- stituting the gastro-splenic ligament, and pass- ing off to the stomach, where they become continuous with its serous covering. When the ligament uniting the spleen to the dia- phragm exists, the membrane is similarly con- tinuous with the peritoneum covering this muscle. The serous membrane is a thin, mo- derately strong, whitish membrane, which is intimately connected with the fibrous coat ; although in particular places, and especially after previous maceration, the two mav be separated from each other. In respect of its microscopical structure, it scarcely differs at all from other parts of the visceral layer of the peritoneum; thus it consists of an outer and single layer of polygonal pavement epithelium, and of an inner layer of white fibrous tissue, in which meshes of fine fibre of yellow tissue are present in no very considerable quantity. In mammalia, e. g. in the sheep, ox, &c., * In this and the following measurements the German inch and line have been retained. t London and Edinburgh Monthly Journal, April, 1813. ' as was remarked by Malpighi, the serou membrane is easily separated entire. But ii man this is not the case, and hence Halle anti others have supposed that only oni membrane is present. But microscopical re search proves the opinion to be erroneous and pathological anatomy confirms this state ment, by showing that the outer part of thi coat of the spleen shares in the diseases o the peritoneum. In animals numerous vessel are seen in the serous membrane, and a ver dense network of stronger and thicker fibre of yellow tissue is present. 2. The fibrous coat ( tunica fibrosa, albu ginea, sive propria) is in man a moderate!; delicate semi-transparent, but firm, membrane which encloses the parenchyma of the spleei on every side, so as to include it in a kind o sac. Its outer surface is even, and in mai is intimately united with the serous covering with the single exception of the hilus, when the two membranes diverge, and are separatee from each other by vessels, nerves, and t loose areolar tissue. The inner surface boundi the parenchyma of the organ, and, with the exception of very numerous solid processei which come off from it, is limited by the tra becular tissue. At the hilus of the spleen ii sinks into the interior of the organ in tin shape of tubes ( vagina vasorum), which en sheath the entering and emerging vessels, am are continued on these throughout the wholi parenchyma. The fibrous coat, in the human subject, is composed of white fibrous tissue mixed with elastic or yellow fibres. The former of these, as in other fibrous membranes, consists of bands, which take a parallel course, but do not form distinct bundles ; and the latter are united in a very dense and irregular network. Duvernoy and Stukely have de- scribed muscular fibres Fig. 522. j,, this tunic ; but, ac- cording to my re- searches, they certainly are not present in the human subject, al- though I have found them existing in some of the mammalia, and most visibly in the dog and pig. They are un- striped muscles, the elements of which, the elongated cells or “ fibre cells” (fig. 522.) which I have described *, are deposited in consider- able quantity amongst the elastic network and white fibrous tissue previously mentioned. Muscular fibre-cell from In addition to these the tunica propria of the two animals I have also spleen of the Dog, mag- founc[ the muscular nifieei 350 diameters. structure in the Ca', the ass, and the Dicotyles a, nucleus of the same. * Zeitschrift fiir wissenscliaft.Iiche Zoologie, von v. Siebold und Kolliker, Leipzig, bei Engelmann, Jalirgang, 1848, Heft 1. SPLEEN. orquatus, while it was absent in the rabbit, rnrse, ox, hedgehog, guineapig, and bat. The elastic fibres of this tunic are for the most iart much stronger than in man. Their peculiar vessels and nerves I have lever witnessed. 3. The trabecular tissue, (trabecuke lienis, talks, or joists of the spleen), consists of white, shining, flat or cylindrical fibres, which arise n great numbers from the inner surface of the fibrous coat ; and, in smaller quantity, from he exterior surface of the sheaths of the ves- sels. These are so connected with similar ibres in the interior of the spleen as to con- stitute a network which extends throughout he whole organ. Between the fibres of this let exist a great number of spaces which are ’onnected with eacli other, and are occupied ly the red spleen-substance and splenic cor- luscles ; and which, although very irregular in ■espect of their form, and, as regards their size, of the most variable dimensions, have yet i considerable resemblance to each other. The older anatomists regarded these spaces is regular and uniform cavities provided with i special membrane. But this last structure lowhere exists, as may be verified in a spleen n which, after short maceration, the pulp has reen removed from these spaces by washing. Such a preparation will also afford the best neans of studying the mode of connection of :he fibres, and in this manner it may be seen :hat, although they are of very different diame- lers, yet the finer fibres are not everywhere given off’ from the thicker ones. This is es- pecially shown by the fact, that fibres of the most different diameters are intimately con- nected together at all points. Where four, five, or more of these joists meet, there generally oc- curs a knot of a flattened cylindrical form, which is not unlike that of a nerve-ganglion. Such knots are more frequently found to- wards the outer surface of the organ, since the cross-beams are more numerous here than in the interior. In this latter part, namely in the neighbourhood of the great vessels, the nume- rous ramifications of these tubes themselves serve as points of support to the pulp, and consequently render the joists less necessary. The structure of the trabecular tissue of the human spleen completely corresponds with that of the fibrous tunic, since it consists of white fibrous tissue and the yellow fibres. The former of these two structures exhibits parallel fibrillce, which run without exception in the direction of the long axis of the parti- tion or joist, and rarely unite into individual bundles. The latter consists of somewhat finer and stronger yellow fibres, which anas- tomose with each other ; their maximum di- ameter is 1,1000th of a line: the greater number of them lie between the bundles of white fibrous tissue, and are easily recognised by their irregular course and manifold curves. Many anatomists, with Malpighi, had spoken of muscular fibres in the partitions of the spleen, although none had succeeded in de- monstrating them, either with the scalpel or microscope, or chemically. But in 1846 I dis- 773 covered them with the aid of the microscope, in the spleen of the pig.* Here they exist both in the finest and largest of the partitions, but they are not isolated, being connected with the finer reticulations of the yellow fibres (jig. 523.). In the larger partitions which are Fig. 523. A trabecula from the Spleen of the Pig, magnified. 350 diameters, and treated with acetic acid. a, muscular fibre-cells with a projecting extremity. or not isolated ; b, nuclei of the same ; c, elastic fibres. visible to the naked eye, the muscular and elastic fibres are present in pretty nearly equal quantities, consequently these parts are to be regarded as alike elastic and contractile. But in the smallest and microscopic cross-beams the muscular fibres predominate, and often they appear to be even unmixed with elastic fibres. In these parts the quantity of white fibrous tissue is still smaller than that of the yellow ; indeed, in this animal it is but very sparingly present in the larger partitions. The direction of the fibres above-named is always longitudinal or parallel to the long axis of the joist, never transverse. In similar extent and quantity, and with a like connection to the elastic tissue, I have found muscular fibre in the dog, the ass, the cat, the Dicotyles tor- quatus, the sheep, rabbit, horse, hedgehog, guineapig, and bat. In the ox, on the con- trary, it exists only in the finer and micro- scopic partitions, where it is present in very considerable quantity and in remarkable dis- tinctness. The remainder of the trabecular tissue consists only of yellow fibre in union * Mittheilungen der naturforschendec Gesell schaft in Zurich, 1847, S. 120. 3 D 3 774 SPLEEN. with some white fibrous tissue. As to the lower vertebrata, I have examined a great number of them with respect to this muscular structure, and have found that the smallness of the spleen in many of them offers a great obstacle to observation ; yet I believe I have verified that the spleens of the pigeon, sparrow, blindworm, tench ( tinea chrysitis ), and trout, contain muscular fibres. So, also, my friend Professor Ecker, of Basle, has orally commu- nicated to me that he has found very dis- tinct muscular fibre in the spleens of the ray and shark. All these muscles are, like those of the fibrous coat, unstriped ; their elements consist of elongated shortish fibres, each possessing a long nucleus. (Fig. 523. a, Fig. 524.) In the thicker partitions there are what I call “ mus- cular fibre-cells,” either stiff, pale, flat, from 4 to G.lOOOths of a line broad, and2 to.S.lOOths long, or more cylindrical, darker, spindle- shaped, and undulating, varying from 2 to 5.100ths of a line in length, and 3 to 4.1000ths in breadth. In both cases they have long, neat, small, staff-shaped, nuclei. In the finer partitions, on the contrary, appear many shorter and more spindle-shaped fibre-cells ; their nuclei are elliptical or even spherical, and they often project laterally from the fibres, so as sometimes to render these muscular elements scarcely distinguishable from the spindle- shaped epithelial cells of the splenic arteries. The muscular elements lug. 5-4. just described are seen in the best and plainest manner in the pig and dog ; but they are also readily verified in the horse, ox, ass, sheep, and cat, in all of which they may frequently be isolated. In the other mammals previously named, and in the rest of the vertebrata, they are less easily recog- nised, and are scarcely susceptible of isola- tion ; but they can al- ways be partially un- covered, and in any case may be demon- strated by the applica- tion of acetic acid, which displays their characteristic nuclei. As regards the hu- man subject, I find that in the partitions which are visible by the naked eye, no trace of un- striped muscular fibre is present; and they probably consist entirely of yellow and white fibrous tissue. In the finer partitions, on the contrary, elements occur to which one may perchance ascribe a muscular character. They are the same short fibres of a peculiar kind (fig. 525. 1.), which Giinsburg* has Muscular fibre-cells from the trabecula of the Pig, magnified 350 diameters. 1, without acetic acid ; 2, with acetic acid ; a, nucleus. Bathologische Gewebelehre, Band. i. S. 81. Peculiar structures from the human spleen, magnified 350 diameters. 1, spindle-shaped fibres with a nucleus ; 2, a cell, which contains such a fibre ; 3, a similar cell, without a fibre. erroneously regarded as epithelial cells of the splenic veins; otherwise they have hither- to remained altogether unnoticed. They are characterised by their roundish or elongated oval nucleus, which is laterally disposed, and often occupies a pedunculated process ; by their homogeneous texture ; by their easy undulatory or serpentine outline ; and, finally, by their size, which offers a breadth of 15 to 25-1000ths, and a length of 2 to 3-100thsofa line. The round nuclei of these fibre-celH even at first sight, somewhat militate against their muscular import ; but it must be recol- lected, that in the mammals named it has been previously stated that the muscular fibre-cells, which occur in the smallest partitions, deviate considerably from the characteristic fibres, and greatly resemble the structures now de- scribed in men. On this account, and from the further fact, that the above mentioned human fibre-cells, in moderately fresh spleens, seem to occupy the smallest partitions, just as the muscular fibres in animals ; while in later periods after death, or in decomposed spleens, they can only be found isolated, with the pa- renchyma cells, in the red pulp of the spleen, I formerly considered it not too hazardous to regard them as muscular fibre-cells. But more recently I have made some observations which have again thrown me into complete uncer- tainty in respect of the import of these ques- tionable structures. Thus I believe myself to have verified, that these fibres occur in 'he human subject rolled together in a kind of spherical cell (fig. 525. 2,) of 5 to 7-1000thscf a line in diameter ; and that, on tearing up this structure they become free, and extend themselves., But, since this fact in no way harmonizes with the nature of muscular fibre- cells, anil is besides altogether obscure and incomprehensible to me, I hesitate to express at once an opinion concerning the above- mentioned structures in the human spleen, but am desirous of calling the attention of inquirers to this peculiar arrangement, which, on ac- count of its constancy and frequency, is very interesting SPLEEN. 775 4. The splenic corpuscles or Malpighian cor- puscles of the spleen (yesiculee sen glandules lienis, s. corpuscula Ma/pighii ) are whitish spherical corpuscles, which are imbedded in the red spleen substance of certain animals, and are connected with the smallest arteries. In the dead bodies of men, in the state in which they are generally subjected to examination in hos- pitals, these corpuscles are very seldom seen. On this account, some of the earlier observers, as Rudolphi, Heusinger, Andral, and others, and more recently Gluge * * * § and Oesterlen f, have regarded them as not constant structures, or even as products of disease ; or have considered them as J. Muller formerly did J, to be altogether distinct from the splenic cor- puscles of the Ruminantia. But this view is erroneous, and since Giesker §, Krause ||, and Bischofff, who described the splenic cor- puscles of the human subject, and showed their correspondence with those of the mam- malia ; and since the revocation by Muller of his earlier opinion **, all observers are tolerably agreed, that although the corpuscles in question are often deficient in the human subject, yet they are not the less to be re- garded as normal structures, which are in- variably present in the healthy subject. The frequent deficiency of the splenic corpuscles is explained by many circum- stances. Most of the observations of them concern human individuals, in whom a long abstinence from food has preceded death. In such cases, as Henle has well remarked f f , the apparent absence of the corpuscles is easily explicable, since their size is notoriously regulated by the quantity of ingesta. So, also, great number of the human spleens which come under our notice are diseased; either softened, distended with blood, and soaked through with extravasations, or enlarged, hardened, atro- phied, or already half decomposed and putrified. Finally, the human spleen corpuscles are very delicate, and easily destroyed. As to the fre- quency of their occurrence in diseased sub- jects, we are supplied with accurate data by v. Hessling, who has given the results of 960 dissections. Of the whole number just men- tioned, Malpighian corpuscles were only pre- sent in 116, or in about every eighth indi- vidual. He also adds the following numerical statement respecting the different ages of life. In the first and second year of life the cor- puscles were present in every second subject ; from the second to the tenth year, in every third subject ; from the tenth to the fortieth year, in every sixteenth ; from the fortieth year to old age, in every thirty-second. These numbers are in general correct, and are readily explicable when we recollect that diseases of * Haser’s Archiv. fur die g'esammte Medicin, 1841, SS. 83. 88. ' f Beitrage zur Physiologie des gesunden und kranken Organismus, Jena, 1813, S. 48. J Muller’s Archiv, 1824, S. 80. § Splenologie, S. 159. || Anatomie, Band. i. S. 520. *|f 31 idler’s Archiv, 1838, S. 500. ** Physiologie, Aufl. 4. Band. i. S. 466. ft Algemeine Anatomie, S. 1000. the spleen are more numerous as age ad- vances. But the results of my own observa- tions coincide with those of Oesterlen, in representing the number of cases in which corpuscles are detected as greater than that above mentioned. This difference may be ascribed to the difficulties which often prevent the recognition of the dwindled spleen cor- puscles; thus in many cases where the first view has afforded no signs of their presence, the application of soda, or the washing of the pulp, has brought them into view. On the other hand, it is absolutely certain that, in many spleens, they disappear without leaving any traces, and cannot be made visible by any method of treatment. In the bodies of healthy individuals which are examined while fresh, they may always be detected ; at least, there are very numerous observations extant in which they have been found after accidental deaths, executions, suicides, &c. ; and to these cases I myself am enabled to add two. So, also, I have found them in a great majority of the bodies of children which I have examined ; and here they are both very' distinct and numerous, so as not to offer anyr visible difference, in these respects, from those of the Ruminantia. The size of the Malpighian corpuscles ex- periences many variations both in men and animals, even apart from the effects of dis- ease : they measure from one-tenth to one- third of a line; on an average, about one-sixth. Their size has hitherto been somewhat too highly estimated ; and chiefly on this account, that sufficient preliminary care has not been taken to isolate them from the surrounding parts : when this is done it will be found, that they are not so large as appears from viewing them on a section of the spleen ; and that, in many cases, they measure less than the given bulk. The fluctuations in their size depend not merely upon the differences of individuals, but obtain in one and the same animal : in this latter case, they appear mainly to be regulated by the condition of the chylopoietic viscera ; although accurate data, as to these points in the human subject, are altogether deficient. It is also possible, as Oesterlen has sup- posed, that these corpuscles experience a certain course of development ; and that, in many cases, the very small corpuscles are very young and undeveloped ones : but, hitherto, I have not been able to observe facts import- ing the certain existence of a continual deve- lopment of the Malpighian corpuscles in the adult animal ; nevertheless, I cannot avoid mentioning that, like Oesterlen, I have seen in the spleens of animals little heaps (from 2 to 4-lOOths line in size) of cells, which have no distinct cell walls, and which, possibly, have some relation to the formation of the splenic corpuscles. It seems quite certain that the spleen corpuscles are not developed from separate cells of the spleen pulp ; al- though this view has lately been brought for- ward in a singular manner by Heinrich.* * Die Kranklieiten der Blilz, 1847, S. 15. 3 d 4 776 SPLEEN. The Malpighian corpuscles are imbedded in the red spleen substance, and, with the ex- ception of one point, where they are attached to arterial twigs, they are everywhere sur- rounded by this substance. They are con- Fig. 526. A small arterial trunk with Malpighian corpuscles, on a somewhat larger artery. From the spleen of the Pig. Magnified 10 diameters. a, the artery ; b, the sheath of the same ; c, Mal- pighian corpuscles ; d, pencils or tufts of arteries. nected to the small arteries and their twigs by short peduncles, like the berries of a bunch of grapes ; and, in such wise, that a small arterial trunk of from 2 to 4-lOOths line, with its ramifications, supports 5 to 10 corpuscles. (Fig. 526.) The peduncles of the corpuscles are almost always small arteries, which pass to be distributed to them ; but in less frequent instances, they are constituted by short pro- cesses of the arterial sheaths, which are con- tinuous with the membranous wall of the corpuscle. In this manner the majority of the Fig. 527. A Malpighian corpuscle from the spleen of the Ox in connection with a small artery, magnified 150 dia- meters. a, wall of the Malpighian corpuscle ; b, contents of the same; c, coat of the artery; d, sheath of the same. corpuscles are essentially devoid of a peduncle, and sit immediately on the arteries at their points of bifurcation, or at their sides. (Figs. 527, 258.) This relation, which also obtains Fig. 528. Malpighian corpuscle from the spleen of the Pig in connection with an artery from which a branch passes to the corpuscle. Treated with soda, and magnified 250 diameters. a, wall of the corpuscle ; b, elastic fibres in the same ; c, sheath of the artery ; d, dissolved middle tunic of the artery ; e, elastic inner coat, in animals, formerly appeared to J. Muller as indicating the fact that the splenic corpuscles were hollow excrescences of the vessel-walls, or were imbedded in these latter. But if by this be understood, what Muller’s plates and description imply, that the sheaths of the vessels, in their whole thickness, with all their elements, are continued to form the cor- puscles, then it is certainly incorrect : for in some animals I have seen that, from the rich network of elastic fibres and muscular struc- ture of these sheaths, little or nothing passes to the corpuscles : and I have generally found the membrane of the corpuscle very delicate. It is, however, quite conformable to truth, to state that this membrane has a direct con- tinuity with the arterial sheaths. (Fig. 521, 528.) The corpuscles do not possess any con- nection with the trabecular network, still less that which Gerlach has lately attributed to them : viz. that they serve as points of sup- port to the elastic fibres of the partitions ; a belief which is altogether baseless. It is difficult to say any thing definite re- specting the number of the splenic corpuscles. Hessling believes that, in some cases, they constitute from one-fifth to one-sixth of the whole splenic mass ; and this seems to me no overstatement, if we substitute the expression “ spleen-pulp ” for “ spleen-mass.” At least, I have found, that their quantity is very considerable ; and that in some instances, when they are rather turgescent, the whole pulp appears as if besprinkled with white. They stand so thickly together, that in many places they touch each other’s sides ; and in others are only separated from each other by narrow interspaces, which in the least favour- able circumstances are about one to two lines in size. I believe that the estimate, that one and a half to two lines of spleen-pulp con- SPLEEN. 777 tains one Malpighian corpuscle, is rather too little than too large. As regards the lower animals, it would follow from my researches, that the Malpighian cor- puscles occur in Mammalia in precisely the same way as in Man ; at least, in more than twenty genera which I have examined, I have never found them to be absent. It has long been known that they are very distinct in pigs, sheep, oxen, goats, and so also in guinea pigs, hedgehogs, and bats, &c., in whom they are rather larger and more resisting than in Man ; and although in the dog, cat, and rabbit, they are somewhat smaller and more covered by the pulp, yet they are nevertheless very dis- tinct. As to Birds, Bardeleben seems to have recognised the Malpighian corpuscles in swal- lows, pigeons, and geese ; while I have been able to verify their existence in sparrows, although they are not particularly distinct. So also Ecker briefly states, that he has seen them in birds ; and Oesterlen mentions their occurrence in the fowl, pigeon, and in many of the Raptores. Amongst the Reptilia, J. Muller has detected them in the Chelonia ; while I have seen them very distinctly in the anguis fragilis, in whom the corpuscles were surrounded by a beautiful network of capil- laries. Amongst the naked Amphibia , Oesterlen states himself to have seen them here and there in toads and frogs ; but in direct op- position to this, I have found no trace of them. Just as little have I been able to de- tect them in Fishes, although I have examined many of the fresh-water genera with this especial purpose. And thus the conjecture of MLiller*, — that they exist in all the verte- hrata, although in none so distinct or so easy of observation as in the vegetable-eating mammals — must be considered as incorrect : a cirumstance which is not without consider- able interest in the determination of their import. On inquiry into the more minute structure of the Malpighian corpuscles, it is exceedingly necessary to regard, not only their appear- ances in Man, but also in the lower animals. Each Malpighian corpuscle possesses a mem- brane and contents, and therefore is not a solid corpuscle, but rather a vesicle. The mem- brane which Malpighi beheld, was minutely described for the first time by Muller and Giesker. According to the first of these ob- servers it is, as previously mentioned, a pro- cess of the common sheath of the vessels, which either immediately continues as a ve- sicular swelling of the same, or is previously produced into a peduncle. Giesker rejects this view, at least as regards the human sub- ject, and describes in each corpuscle a pecu- liar, independent, and tolerably strong mem- brane, which seems to have no connection with the sheaths of the vessels, but receives an additional thin outer covering of white fibrous tissue, in which the vessels of the cor- puscle ramify, and to which they frequently impart their own red colour. The ma- * Thysiologie, i. S. 486. jority of later observers have unconditionally adopted one or the other of these views ; only a few of them, as J. Simon, Henle, Ecker, and Oesterlen, having taken the trouble of substantiating their truth by original inquiry. Henle, Oesterlen, and J. Simon, deny the existence of a special membrane. The first of these observers finds that the wall of the corpuscles is constituted solely of granules, under which appear to be comprised struc- tures resembling the morphous part of the contents ; while fine bundles of white fibrous tissue unite on their outer surface. Oesterlen and J. Simon likewise deny the peculiar mem- brane (limitary membrane), an absence which the latter associates with the capacity of the corpuscles to fill themselves out from the capillary vessels. So also Bardeleben de- scribes a membrane very indistinctly. On the other hand, Ecker* has assured him- self of the presence of a membrane in mam- mals and birds. By the application of pot- ash, the masses of granules which seem to constitute the wall of the corpuscle were dis- solved ; and he then not only saw the rami- fications of the arteries on the Malpighian cor- puscle with great distinctness, but he also recognised that this possesses a distinct mem- branous wall, in which a network of ex- ceedingly fine and well-defined stripes could be detected. Although these stripes are actual fibres, yet, according to Ecker, they everywhere cover a structureless gland-mem- brane, for the wall of the vesicle is never interrupted in the structureless intervals be- tween these fibres ; indeed it is possible that the latter are themselves but folds of a structureless membrane. Amongst the most recent authors, Arnold f and Huschke j ac- cept Giesker’s view, and Dr. Gerlach § re- peats Ecker’s decision. As to myself, in the first place, l regard it as an incontro- vertible fact, that the Malpighian corpuscles possess a special membrane. If one of the vesicles be isolated, and sufficiently separated from the surrounding tissues, it may be seen without any further preparation, especially with a slight pressure (Jig. 527.) ; and it be- comes particularly distinct if a little dilute soda or potash be applied (Jig. 528.). These reagents dissolve all the surrounding parts of the pulp, with the exception of the ves- sels, and thus leave the membrane of the vesicle, although somewhat altered, yet quite entire. Concerning the nature of this mem- brane, I have veritied the following : it is colourless, transparent, about 1 to 2-1000ths of a line in thickness, has everywhere two contours, and here and there it exhibits con- centric lines. Its structure so far corresponds with that of the sheaths of the vessels with which it is continuous, that it contains at least white fibrous tissue and elastic fibres ; but the unstriped muscular fibres which oc- * Der feinere Bau der Nebennieren, 1846, S. 10. f Anatomie, ii. S. 123. | Eingeweidelehre, S. 178. § Zeitschrift fur Rationelle Medicin, Bd. vii. S. 77. 778 SPLEEN. cur in these sheaths in many animals, are altogether absent from the membrane of the Malpighian corpuscle ; and the latter must especially be noticed as being much more de- licate than the sheaths of the arteries on which the corpuscles sit. The white fibrous tissue, which Ecker regarded as a continuous membrane, in consequence of having seen it when changed by the action of potash, is in precisely the same condition as in the par- titions and sheaths of the vessels, and forms by far the greatest part of the coat of the cor- puscles ; while the elastic tissue (the stripes of a doubtful nature which Ecker saw) ap- pears to constitute only a more or less ex- tensive network of pale, so-called nuclear fibres (kernfasern) {fig. 528. b ). So that the membrane of the Malpighian corpuscles would thus appear to be only a modified portion of the vascular sheath, — a view which most ap- proximates to that enunciated by J. Muller. An outer coat, of which Giesker speaks, has never been plainly verified by me as a special membrane connected with the preceding ; but it seems to me more probable, that the cor- puscles are alway's immediately surrounded by the cells and vessels of the pulp. Certainly these vessels are often connected together by an indistinct fibrous or membranous sub- stance, but this is especially present in the pulp, and is nothing else than the termination of the sheath of the vessels. The preceding remarks especially apply to the Malpighian corpuscles of the higher brute mammalia. As to those of man, although they are much more difficult to examine, yet I have satisfied my- self in the most positive manner that they correspond with those of the brute mammalia in all essential points. This is easiest and best seen in the spleens of children. The struc- ture of these is exactly that seen in animals, only the coat is more delicate, so that it is extremely difficult to isolate a single cor- puscle entire, and the contents are expelled by the slightest pressure. In the wall is seen the same network of elastic fibres as in ani- mals, and this renders it possible even to re- cognise those which are burst. Extremely fine capillaries of 3-1000ths of aline in diameter may frequently be seen around the corpus- cles ; but the latter are just as little enve- loped in a second membrane as in animals. The Malpighian corpuscles do not possess in their interior an epithelium and separated contents like the glands, but they are densely filled with a semifluid, greyish white, cohesive mass {fig. 527. b). This contains, together with a small quantity of a clear fluid, a large quantity of morphous particles, which have been very differently described by different observers. According to J. Muller they very much resemble the corpuscles of the spleen- pulp, and have a general likeness to the blood discs, but are irregularly spherical. Bischoff regards them as altogether corresponding with those of the chyle, both in appearance, size, and behaviour with water and acetic acid. According to Henle, they resemble those of the spleen-pulp and those of the thymus and thyroid body ; and he so de- scribes them, that it would appear he recog- nised nuclei and a small proportion of cells. Oesterlen describes them as nuclei resembling the elements of the pulp. Hessling, Huschke, and Nasse# agree with Bischoff respecting the similarity of the elements in question to the lymph and chyle corpuscles. The latter of these authorities finds those of the rabbit to be 2 — 3-1000ths of a line in diameter, while Hessling certifies to their size in men as from 2 — 5i-1000ths, and describes their surfaces as possessing a mulberry-like ap- pearance, and their contents as partly minute granules, partly separate nuclei. J. Simon found that the corpuscles in question never attained a development into cells. Bemakj describes them as consisting — partly of large transparent cells, with an interior containing a single lateral, or double and clear nucleus — partly of small, dark-bordered vesicles, closely surrounded by a delicate pale membrane, and occupied by a dark central nucleus. The first, according to him, resemble the larger, the last the smaller lymph corpuscles. Fi- nally, Gerlach finds in the Malpighian cor- puscles the nuclei of cells, and, in equal quan- tity, cells of different sizes, with one, two, or three nuclei, as well as blood corpuscles, with all those forms of granule-cells which I shall hereafter describe as developed in the spleen- pulp from the effused blood. These are the most important accounts given by others. As the result of my own researches, I must, firstly, corroborate J. Mul- ler, who explains the elements of the contents of the Malpighian corpuscles and spleen-pulp as similar structures. Also, I can add with Bischoff, that they often resemble the chyle corpuscles ; yet I am not disposed to lay any weight upon this correspondence. Further- more, I consider it fully made out that Ger- lach’s view, according to which blood cor- puscles, and cells which include blood cor- puscles,are a constant constituent of the Mal- pighian corpuscles, is altogether erroneous. They are not even frequent occurrences, for in many animals I have not found them at all ; and when they occurred — as, for instance, in oxen — they were mostly found in scattered vesicles, and, further, were in such small quantity, that they had no influence on their colour. And very often blood corpuscles and their metamorphoses appeared to occupy the vesicles, w'here a more careful examin- ation showed that they were only in con- tact with their outer surface. The degree of accuracy to which Gerlach’s assertion may lay claim is best shown by the fact, that he al- together denies the existence of these granule- cells (which are produced from the effused blood) in the spleen-pulp ; while it is here, as well in these as in animals which possess no proper spleen vesicles, that they' occur in * Handworterbucli der Physiologie, von B. Wag- ner, ii. S. 387. f Diagnostische mi d Patfiogenetisclie Untersuch- ungen ; Berlin, 1845. SPLEEN. 779 the greatest quantity, and are most easily seen. The constant and essential elements of the splenic vesicles are cells, with a single nucleus of a spherical shape, and from 3 to 5-1000ths of a line in diameter: besides these, free nuclei, and larger cells of 6-1000-ths of a line in diameter, and with one or two nuclei, also occur (Jig. 529.). The cells are in general pale and faintly granular ; their nuclei are from 16 to 25-10000ths of a line in size, spherical, apparently homogeneous, and with a rather dark margin ; or frequently vesicular, with a more or less distinct nucleolus and other granules. It is not infrequent to see Fig. 529. Elements of the Malpighian corpuscles of the O r, mag- nified 350 diameters. a, smaller cells ; b, larger cells ; c, free nuclei. single cells provided with dark fatty granules, and in particular instances blood discs are present, either changed or unchanged, free or included in cells. The free nuclei are of the same size as those contained in cells, and are also, in other respects, quite similar to them. In the ordinary method of examining the Malpighian corpuscles, the quantity of them nuclei seems larger than it really is, since many of the cells burst, and allow their nu- cleus to escape. Yet it is very remarkable that their number is very variable in the most cautious examination, a fact which appears to me partly to account for the very different statements of different observers. In many cases it has happened to me to find only a few free nuclei, often none at all, while in other instances they constitute a half or more of the elements of the corpuscles. This fact, taken together with the often very different size of the cells present, seems to prove that a continuous process of cell-growth exists in the Malpighian corpuscles ; in such wise, that new nuclei and cells continually arise, and old cells perish. But hereof more will be said in speaking of the pulp, in which the same pro- cess obtains. If, after these remarks, we take a glance at the import of the Malpighian corpuscles, we shall be compelled especially to ask ourselves, first, whether they are the beginnings of the lymphatics, or in any other way connected with them ? and, secondly, whether they have the import of glandular vesicles ? A connection of the Malpighian corpuscles with the lymphatics was a belief of many anato- mists in earlier times, and in our own days has been recently upheld by Giesker, Huschke, Gerlach, and Poelmann. The acceptors of such a theory rest mainly on conjecture, but partially also on facts. Amongst the latter, there may be mentioned — 1. The cor- respondence of the cells in the Malpighian corpuscles with the lymph corpuscles. But we must remember that cells which cor- respond with the lymph corpuscles occur in many other situations where no such connec- tion with the lymphatics can be imagined, as in the spleen-pulp itself, in the pancreas, in the salivary glands, the glands of mucous mem- brane, the thymus, thyroid, &c. 2. Huschke adduces the similarity of the spleen vesicles with the whitish granules of the lymphatic glands, which are dilatations of the lymphatic vessels themselves. Against this it need only be objected, that this latter is a pure fiction of Huschke’s, and that even were it as he states, no conclusion concerning the nature of the Malpighian corpuscles could fairly be deduced from it. I have yet further to men- tion, that, according to an oral communica- tion of Ecker which was made to me many years ago, and recently repeated, concerning the splenic vesicles of the mammalia, processes and pedicles exist which are neither blood- vessels nor partitions, and, therefore, may be lymphatics, — a view with which Poelmann’s and Gerlach’s recent statements are some- what in unison. The former of these two* says that he followed the thoracic duct even to the Malpighian corpuscles, with which it became connected ; but he does not specify more exactly the nature of this connec- tion. The latter says that it has often seemed to him as if the neighbouring Mal- pighian corpuscles communicate with each other through special tubes ; that he has been led to this belief by the circumstance that when the vesicles are compressed, their con- tents are expelled in definite directions, which a closer examination shows to be canals, the coats of which tolerably resemble in texture those of the Malpighian corpuscle ; and that it is thence clear that the corpuscles communicate with a system of tubes which can scarcely be imagined to be any thing else than the lymphatics. And thus, if the Mal- pighian corpuscles are dilatations of the lymphatics, they may possibly be commenced as simple varicose swellings, or, what is more probable, as lateral productions of these vessels. I acknowledge that I am unable to verify this fact last adduced, or to subscribe to this connection of the Malpighian cor- puscles with the lymphatics. In my researches I have given an attention to this point con- formable to its great importance ; and although I have not seen the commencement of the lymphatics in the spleen, yet I have so far come to a positive conclusion, that I am con- vinced of the complete closure of the Mal- pighian corpuscles. What Gerlach states of the tubes into which the contents of the cor- puscles are forced, is altogether erroneous; such tubes nowhere exist. Gerlach appears to have been misled to this opinion by the fact, that when a corpuscle is burst by pres- sure, the contents rush out at several points, * Annales et Bulletin de la Socie'te de Me'dicine de Gand, 1846, p. 267. 780 SPLEEN. and are then effused in the shape of long and small streaks in the surrounding tissues. If the commencements of such a streak were not observed, it might easily be regarded, from its always taking a radiating course from the Malpighian corpuscle to which it is united, as a canal communicating with the same, especi- ally when a longer pressure applied to the corpuscles has elongated these stripes by con- tinually forcing out the contents. The pro- cesses which Ecker has described on the Malpighian corpuscles, and which are not bloodvessels, probably belong to the same category as the artificial products mentioned above ; or, if this is not the case, it is possible that they are small trunks of nerves, which are frequently present in the neighbourhood of Malpighian corpuscles, and which, from reasons that will be hereafter mentioned, are exceedingly difficult to recognise as being what they really are. I therefore maintain, quite plainly and definitely, that the Malpighian corpuscles are closed capsules, and stand in no connection at all with the lymphatics. If this be so — and the structure of the Malpighian corpuscles, which altogether differs from that of vessels, corroborates the fact — it is next demanded may not the Malpi- ghian corpuscles be glands? If by “glands” be meant the word in its ordinary sense, I answer with a decided “no for these alto- gether differ from the known simple shut glandular sacs of the ovary, thyroid, thymus, and supra-renal capsules, and possess neither a structureless membrana propria (limitary membrane, or basement membrane) nor an epithelium. On the contrary, in my opinion, they correspond with the spaces filled with cells in the lymphatic glands, and with the sacs of the glandulae solitariae and agminatae of the intestine. Here and there hollow spaces exist, which possess a covering of white fibrous tissue, are completely inclosed, and contain in their interior no trace of epithelium, but only a coherent mass of nuclei and cells, together with some fluid ; we might call these “ vesicular glands,” recol- lecting at the same time that they possess the function of the real shut glandular vesicles, although their anatomy essentially differs. Although the discussion of the former ques- tion does not belong to this part, yet I will add, that, in reality, there is much to indicate that the structures in question constitute a kind of shut glandular vesicle ; and that, con- sequently, there is nothing to prevent their being regarded as glandular vesicles. 5. The red spleen substance, the spleen-pulp, the parenchyma of the spleen ( substantia ru’:ra, pulposa, parenchyma lienis ), is a soft reddish mass, which fills up all the interstices between the larger partitions and the stronger vessels, and on section of the organ is easily scraped off or squeezed out. It consists essentially of three constituents ; which are, fine bloodvessels, parenchyma cells of the spleen, and small partitions or fibres. To these constituents is so frequently added, both in man and animals, extravasated or coagulated blood in various metamorphoses, that one is almost forced to designate it a normal constituent. According to the pre- dominance or diminution of the latter in- gredient, or according to the greater or lesser distention of the bloodvessels themselves, the spleen-pulp appears sometimes altogether of the colour of the blood, at others of a clearish red, with a greater or lesser tendency towards whiteness. The following remarks apply to the mi- croscopic appearances of the constituents of the pulp, the vessels only excepted, which will be described hereafter. The fibres of the pulp are of two kinds. The one kind, which may be named “ small or microscopic partitions ” (“ microscopische ballcchen ”), are quite analogous to those larger partitions (“ balken”) which are visible to the naked eye ; they are also of the same structure, except that in the lower animals they often contain more muscular fibres than the latter. Their diameter is variable, from 5 to 10-1000ths of a line ; their frequency and quantity also vary in different situations, and amongst different creatures. In the human subject I find them to be fewer and broader than amongst other mammalia, and exactly like the larger partitions in structure ; while in the ox, sheep, &c., they occur frequently, are more delicate, and arc remarkable by their purely muscular structure. The other fibres of the pulp are evidently processes front the sheaths of the larger vessels ; they greatly predomi- nate in quantity, and appear chiefly in the form of delicate membranes of an indistinctly fibrous structure, and without any mixture of elastic fibres, which seem to connect the capillaries to each other. Whether they take the form of small partitions — in which case they could not be distinguished from the small trabecula; — is at present undecided. In animals, these membranes are also present on the veins ; but of this more will be said hereafter, in speaking of the vessels. The cells of the sp/een-pn/p, which I shall call “ parenchyma-cells of the spleen,” have been described by J. Muller as similar to those of the Malpighian corpuscles ; and, as was previously stated, this view has been followed by the majority of writers ; as by Henle, Bischoff, Huschke, Iiemak, and others. Only Von Hessling and Gerlach are of another opinion. According to the former, the globules of the spleen-tissue are distin- guished by their dark colour, and by their being mingled with spindle-shaped cells. Ger- lach finds that cells with nuclei are rare in the spleen-pulp ; while, on the contrary, he considers them to be frequent in the Mal- pighian corpuscles. As to myself, I have already expressed my concurrence with the view taken by Muller, and may therefore for- bear to enter further upon this point ; never- theless, it is necessary to remark that the parenchyma-cells exhibit some additional peculiarities, which ought not to be passed over without notice, A considerable por- tion of these cells completely correspond SPLEEN. 78 1 with the cells of the spleen vesicles ; the characteristic appearances of which are their Fig. 530. Parenchyma-cells from the spleen of the Ox, magnified 350 diameters. a, Smaller cells ; h, cells of medium size ; c, free nu- clei ; d, largest cells. roundness, their size— -from 3 to 5-1000ths of a line — their paleness, and their dark nucleus {fig. 530. b ). On the other hand, smaller and larger corpuscles also occur in the spleen-pulp, which are never met with in the Malpighian corpuscles. The former are small round corpuscles, somewhat larger than blood globules. They are seen in one of two states : either they exhibit a membrane and nucleus inseparable from each other, and thus, apart from their colour and somewhat lighter outline, resemble blood globules ; or they are free nuclei, in which no nucleoli are visible. But only a few of these are free nuclei, for by the application of saliva or a little water a membrane starts into view, either completely enclosing them, or limited to one side {fig. 530. a). The nuclei, which thus appear as something separate from the membrane, have always the dark appearance of those cells the two parts of which are inseparable from each other ; so that the appearance of these latter would seem chiefly dependent on the nucleus. With these small and quasi-developing cells, one also meets with free nuclei ; and careful manipulation of the preparation shows these to be in general more numerous than in the Malpighian cor- puscles {fig. 530. c). The larger named cor- puscles are partly pale cells of 7-1000ths of a line in size, with one or two nuclei^ or granule- cells of 4 to 6-1000thsof a line, and which may be described as “ the colourless granule- cells” {fig. 530. d ) : both of these are more frequent than in the Malpighian corpuscles. The spindle-shaped or fusiform cells which Hessling mentions do not belong to the normal constituents of the spleen-pulp, and are nothing else than epithelium cells of the splenic arteries {fig- 534. b), which in ma- cerated specimens of the human spleen, and in preparations where the vessels have been cut through, easily get into the pulp, and give rise to the delusive appearances of the so-called fusiform cells. The comparative examination of this part of the spleens of many animals confirms what has been al- ready stated of the elements of the Malpi- ghian corpuscles ; namely, the elements of the pulp vary greatly, since sometimes the nu- clei, sometimes the smaller cells, sometimes the greater cells, predominate. And in this, as in the former case, I conclude therefrom that a continuous process of cell growth ob- tains in the spleen, by which new cells are formed around nuclei, and old ones dis- appear. The quantity of parenchyma-cells of dif- ferent kind and shape, and of free nuclei which must be reckoned with these, is a very considerable one ; so much so, as to con- stitute nearly one half of the whole red spleen substance. These do not lie collected in large heaps, but constitute small irregular groups of different size, which occupy the interspaces formed by the partitions of all sizes, the vessels, and the Malpighian cor- puscles. The best method of representing this disposition is to regard each part of the pulp, which is included in a large mesh by trabeculae visible to the naked eye, as con- stituting in a small form what the spleen itself is in a larger. The microscopic par- titions and fibres and the finest vessels thus exhibit the same relations as the larger par- titions and vessels ; while the small nests of parenchyma-cells answer to the large homo- geneous masses of red pulp which are visible to the naked eye. There are nowhere any special coats which include these cells, but they may be seen everywhere placed imme- diately on the sheaths of the vessels, the par- titions, and the membranes of the Malpighian corpuscles. In the above delineation of the parenchyma-cells, those of man and of the higher mammalia have especially served as the model: but in general a complete simi- larity obtains in other animals ; and it is only here and there that any specialities show themselves. In many animals — thus, for instance, in amphibia — the spleen has often, though not always, very beautiful pa- renchyma-cells with large nuclei : in birds, and in the scaly Reptilia, granulated and somewhat dark cells are for the most part more frequent. In the hedgehog, rabbit, and guinea-pig, some cells, which are altogether peculiar, occur in company with the ordinary ones. In both the former of these I saw, here and there, large round cells from 10 to 16-1000ths of a line, with three, four, to ten or more nuclei, which often lay so closely together in the middle of the cell that they appeared to make up a mulberry-like mass, like certain large cells which one finds in the marrow of young bones. These cells were by no means uncommon, but gradually dimi- nished in size towards that of the parenchyma- cells, In the guinea-pig occur round cells, in large quantity, of 48 to GO-lOOOOths of a line, which contain one or seldom two round granules of a dark contour ; and their nu- cleus, not always very distinctly visible, is very plainly seen on the application of acetic acid; while, at the same time, the dark granules often disappear. The blood effused in the spleen-pulp, as well as the metamorphoses of the blood globules in the same, demand the greatest consideration both in respect of anatomy and physiology. I believe myself to have been the first who* directed attention to this circumstance, and cor- * Loc. cit. 782 SPLEEN. rectly recognised it ; although Oesterlen, l'c- inak,and Handheld Jones had already detected isolated facts having a reference to it. Oester- len * was the first who found in the spleen of frogs and toads, and with less distinctness in that of the mammalia, yellow, rose-red, and black minute corpuscles, but he was not in a condition to explain them. Remak followed next without greater success ; he found in the spleen-pulp of the calf delicate trans- parent vesicles, with 1 to 3 round, reddish- yellow homogeneous bodies, the colour of which approximated to that of the blood corpuscles, but which were not so easily swollen out by water. Finally, Handheld Jones f discovered peculiar yellow corpuscles in the spleen of different vertebrata. All these facts are placed in their true light by my discovery that blood corpuscles are almost constantly undergoing dissolution in the spleen and disappearing. This will be shown as follows : — The red pulp of the spleen in man and animals exhibits at different times a different Fig. 531. 1 Cells containing blood corpuscles from the spleen of the Rabbit, magnified 350 diameters. 1, cells with one, three, four, and seven unchanged blood corpuscles ; 2, cells with blood corpuscles undergoing dissolution, and coloured in different shades of brown or yellow (coloured granule cells) ; 3, cells with destroyed and decolorized blood globules, larger or smaller, and with or without granules ; 4, blood globules altered in colour, di- minished or destroyed, either single or aggregated, in small clumps. In 1, 2 and 3 the following letters signify alike : — a, more or less unchanged blood globules ; e, co- lored granules begun by a diminution or destruc- tion and alteration of colour in blood corpuscles ; d, colourless granules produced by the discolor- ation of c ; e, nuclei of the cells containing blood corpuscles and their metamorphoses ; f, nucleoli of these nuclei. colouring, or rather a different condition of the blood corpuscles contained in it, and * Loc. cit. p. 52. t London Medical Gazette, Jan. 1847, pp. 140- 142. these, without any participation of the other elements, affect its colour by the different nature of their appearances. Thus, in a par- ticular animal or in the human subject, this sub- stance sometimes possesses a paler or more greyish red, sometimes a brown, or even black-red colour : in the latter case a quan- tity of altered blood globules are present, the appearances of which will hereafter be de- scribed ; while in the former case, it may easily be proved by the microscope that the red colour depends on unaltered blood globules, which are easily separated from the pulp by pressure, and on the application of water give off all their colour in a short space of time. In other animals, the spleen has always about the dark colour mentioned : nevertheless, even in these cases, sometimes only un- changed blood globules are seen ; sometimes many of these are undergoing the most manifold changes. Now these changes (figs. 531,532.) are very extraordinary and peculiar, and in all animals depend essentially upon these facts. The blood globules first become at once smaller and darker, while the elliptical corpuscles of the lower vertebrata also become rounder : then, in connection with some blood plasma, they become aggregated into small round heaps; which heaps, by the appearance of an interior nucleus and of an outer membrane, experience a transition into spherical cells containing blood corpuscles. Thesg. are from 5 to 15-1000ths of a line in size, and contain from 1 to 20 blood corpuscles (figs. 531. 1. 532. 1.) During this time the blood cor- puscles are continually diminishing in size, and, assuming a golden yellow, brownish-red, or dark colour, they undergo, either imme- diately or after a previous dissolution, a com- plete transition into pigment granules. So that these cells themselves are changed into pigmentary granule-cells ; and, finally, by a gra- dual loss of colour of their granules, they form themselves into completely colourless cells (figs. 531. 3. 532. 4.). In respect of the more special circumstances of this process, it is first necessary to con- sider the commencement of the cells de- scribed, and their changes, somewhat more in detail. As regards the first of these, it is certain that the cells containing the blood corpuscles do not commence directly around a nucleus, but by the circumposition of a membrane around a heap of coagulated blood : in the same way, to wit, that the so-called inflammatory globules of Gluge in certain cases change themselves to cells ; or that by which the smaller globules of fission of the yolk form themselves into vesicles. On the other hand, it remains doubtful whether the nuclei which are seen in these cells are there before the formation of the membrane, or whether they only begin as supplementary to it. If the former be the case, one might add that, in the extravasated or clotted blood of the spleen, nuclei arise in consequence of the commencing organization, each of which then, like the nuclei in the fission of the yolk, SPLEEN. surrounds itself with a part of the blood (plasma and globules), and, finally, con- F/g, 532. Cells containing blood corpuscles, from the spleen of the Frog ( liana temporaria and esculenta), magnified 350 diameters. 1, cells with one or more blood globules of an intense yellow colour, diminished in size, yet mostly not yet destroyed ; 2, cells with blood globules coloured brown, orange, or black, still more diminished and dissolved (coloured granule cells) ; 3, cells with blood globules much diminished or quite dissolved, and undergoing discolorization (pale-coloured granule-cells) ; 4, cells with completely dissolved and discolorized blood globules (colourless gra- nule-cells) ; 5, coloured granule-cells (like those in 3) in different stages of their transition into black pigment-cells. In 1 — 5 the letters import, as in fig. 351. b, the nuclei of the blood globules. ditionates the development of a membrane on the surface of the sphere thus commenced. Or one might regard the formation of spheres consisting of some blood plasma and blood globules as the primary phenomenon ; and that then a nucleus begins in each sphere; and that, finally, a membrane is thrown around these. In corroboration of this opinion, Hasse and myself* have observed in the pigeon the occurrence of inflammatory globules, which are without nuclei or membranes, but contain blood globules ; and to this may be added, that in the splenic extravasations blood cor- puscles are often grouped together in heaps without being contained in cells. Be this as it may, in any case thus much is certain, that as soon as the cells with their included blood globules are visible, the nuclei are never absent ; and this fact, taken in conjunction with what is already known of the import of nuclei in the process of cell development, speaks strongly for their formation preceding that of the membrane of the said cells. These cells containing blood corpuscles * Zeitschrift fur Ration. Medicin, Band. iv. S. 1. 783 behave themselves so far alike in all creatures, that their blood corpuscles by degrees dis- appear and fall to the ground ; "and, ulti- mately, they all seem to be converted into colourless cells, although the methods by which this change occurs are different in different animals ; whence it will be well to go through them one by one. a. In mammals the cells with unchanged blood corpuscles are not very easily seen, on account of the small size of the latter, and the facility with which they lose their colour ; yet one can easily get a sight of them, pro- vided the examination be made at the right time, and the application of water forborne. 1 have seen them plainly in man, the rabbit {fig. 531. 1.), guinea-pig, sheep, calf, and dog ; and have found that in these creatures the number of the included blood globules is from 1 to 12, on an average from 2 to (5, and the size of the cells from 5 to 16-1000ths of a line ; while their vesicular nuclei have a length of 36-10000ths, and a breadth of 28-10000ths of a line. By the shrinking up and falling to pieces of the blood globules, which immediately renders them darker in colour, coloured granule-cells begin from these cells. They are of a golden yellow, or rusty or brownish yellow, or even blackish colour ( fig. 531. 2.), and gradually experience a trans- ition into cells, with slightly coloured, more numerous, and smaller granules; and, finally', they take the form of altogether colourless cells, part of which are even poor in granules {fig. 531. 3.). In man, the rabbit, and the guinea-pig were found, besides the cells just described, free granules and heaps of granules, of a golden yellow, brown, or blackish colour; together with altered blood globules, con- cerning which it seemed to me very probable that they were originally free, and were never included in cells. In other vertebrata, as in the hedge-hog, the cat, and the bat ( Vespertilio myotis and pipisirellus), the cells with the unchanged blood globules were not observed, although all other stages, from the golden yellow to the altogether colourless granule- cells, were seen. Finallv, in others, as in the horse and ass, were seen uncommonly nu- merous,diminished, and highly coloured blood- globules, both isolated and aggregated ; and the metamorphoses of these into golden, brown, and blackish-yellow heaps of granules, although no definite indication of cell struc- ture could be detected around these heaps. b. Amongst birds, I have found the round cells in Falco albicillus, Cuculus eanorus, Turdus varius, Perdix saxatilis, and Sylvia hortensis. They were in larger or smaller quantity, from I to 10-1000ths of a line in size, with dark golden yellow granules which were evidently nothing but metamorphosed blood globules. This was very distinctly shown in Turdus musica, since here the cells occurred with unchanged blood globules. Everywhere these cells experienced a trans- ition, partly into brown and black granule- cells, partly into colorless granulated cells. ' c. Amongst the Reptilia. In the scaly 781 SPLEEN. Reptilia, amongst which I have only ex- amined Anguis fragilis and Coluber austriacus, I have seen no cells with unchanged blood globules ; but in the Anguis I found pale yel- low, brown, and black granule-cells, which were, as in birds, of from 6 to 10-1000ths of a line in diameter. Transitions of these into faintly yellowish and colourless granule-cells were also present in considerable number, being almost as frequent as the ordinary pa- renchyma cells in the spleen-pulp. The Co- luber austriacus certainly exhibited an effu- sion of blood in the parenchyma of the spleen, but no changes of the blood corpuscles. The naked amphibia offered a striking contrast. Amongst them I examined Rana temporaria and esculenta, Bombinator igneus, Hyla ar- borea, Bufo cinereus, Alytes obstetricans, Salamandra maeulata and atra, Triton igneus, taeniatus, and cristatus. The cells with blood globules were better seen in these than in any other animals. This was especially the case in Triton, Bombinator, and Rana, in which 5, 10, 20, and more blood globules, with dis- tinct nuclei, were frequently seen occupying a plainly nucleated cell of 6 to 12-1000ths of a line in diameter. The size of the blood globules in these cases allowed their meta- morphoses to be followed through all stages, as is represented in jig. 532. At first they were round, of an intense yellow, and less easily altered by water ; then they contracted themselves yet more together, assumed a golden yellow or brown yellow colour, and were no longer assailed by water ; finally, they became colourless, or experienced a transition into black granules, while they generally also fell asunder into smaller granules. In this manner golden and brownish yellow granule-cells (Jig. 532. 1.) arise from the cells with unchanged blood globules (jig. 532. 2, 3, 5.), and finally they experience a transition into colourless granule-cells (fig. 532. 4.), or exist for a longer time as black pigment cells. d. \n fishes I have recognised the same con- ditions as in the naked amphibia, only they were not so brilliant. The cells with blood globules were very distinctly seen in Salmo fario, Cyprinus carpio and brama, Tinea chry- sitis, Esox lucius, Perea fluviatilis, Coregonus muroena, and Gadus lota. In Anguilla flu- viatilis, Aspius alburnus, Chondrostoma nasus, leucocephalus, &c., they were less plainly seen; nevertheless, cells with shrunken blood cor- puscles, or aggregates of such, occurred also in these. In" all fishes these structures be- come converted partly into colourless granule- cells, partly into black pigment-cells and pig- ment masses, which finally often lose their colour. The place where the changes of the blood corpuscles above mentioned occur can be demonstrated in some amphibia to be the bloodvessels. Thus, in Triton igneus, the spleen is at its margins tolerably transparent, and here one frequently comes upon the cells which contain blood corpuscles, occupying the capillaries in a row one after another ; and here we are also able to drive them into the larger venous channels by pressure, so that one of these is often filled by a consider- able streak, consisting entirely of these alto- gether characteristic elements. Whether this occurrence is a rule in the Triton, and whether it obtains in other amphibia, I am unable to certify. Yet I may communicate that, in the Triton, frog, toad, and Salamandra atra, I have found these cells containing blood corpuscles even in the trunks of the splenic vein and vena port® ; while in Bufo cinereus, Triton igneus, and Salamandra, I have found them in the hepatic branches of the vena porta?, even to its capillaries ; and in the latter animal, even in the inferior cava and the heart. In any case, these facts may be con- sidered as conclusive of the not unfrequent occurrence and formation of the cells in ques- tion within the bloodvessels of the spleen ; although it can scarcely be added that they are not probably also formed in the extra- vasated blood. In certain genera of fishes, as in Tinea, Esox, Perea, the cells which contain blood corpuscles, and their metamorphoses, are seen included in round delicate-walled vesicles of from l-40th to 1 - 1 Gth of a line in diameter (fig. 533.), which for the most part Fig. 533. Artery (a), with a cyst (b) in its tunica adventitia (c), which contains cells (d) enclosing Hood corpuscles. From the spleen of the Tinea chrysitis. sit on the ramifications of the splenic arteries, either laterally on the vessels, or on the points where they divide ; and which are connected with the sheath or exterior membrane of the same ; or, in other words, are nothing else than poachings of the same. How these ve- sicles are developed I have not determined, yet I can scarcely doubt that they have the import of false aneurisms, and owe their origin to a tearing of the inner and middle tunics, and to a protrusion of the tunica ad- ventitia, together with the sheath of the ves- sels (if the latter texture can be supposed to exist here). The similarity of these vesicles with the Malpighian corpuscles of the mam- mals seems to be especially worthy of men- tion. After the description already given of the relation of the Malpighian corpuscles to the arteries, it is unnecessary to explain in de- tail, that the correspondence of both in re- spect of their site is very great. But, in re- spect of their contents a similar resemblance is sometimes exhibited, when, as in the cysts of fishes, the cells with blood corpuscles SPLEEN. have all undergone a transition into colour- less cells, or the Malpighian corpuscles con- tain effused blood. By pondering upon these circumstances, one might almost come to the idea of regarding the cysts of fishes as Mal- pighian corpuscles, or the Malpighian cor- puscles of mammals as false aneurisms of the splenic arteries ; but in my opinion either of these views would be altogether erroneous. For although blood is often present in the Malpighian corpuscles, yet this appearance is much too seldom to allow of our explaining then- contents as arising out of altered blood. And as regards the cysts of fishes, they are alto- gether absent from many fishes, and, where they are present, often undergo a cretifica- tion, or are changed into concretions ; while they occur in other organs, as for instance in the kidneys : facts which have little confor- mity with the constant occurrence of the Mal- pighian corpuscles. In others of the fishes previously mentioned, no vesicles can be re- cognised in the spleen ; on the contrary, in many genera, the blood corpuscles obtained in different conditions of their metamorphosis are seated together in roundish heaps of a more or less definite outline, and of a size which equals that of the vesicles : these are evidently nothing else than extravasations of blood. The numerous circumscribed red or brown points which occur in the spleen pulp of all fishes, are nothing but the self-decom- posing blood globules ; and they are, as above mentioned, either free or arranged in masses which are included in vesicles. In the scaly reptilia, birds, and mammals, it is very dif- ficult to state with certainty in what part of the spleen the formation of the cells which contain the blood corpuscles and their meta- morphosis occurs. At first 1 thought of the hollow interspaces with which the vein of the spleen begins ; only these spaces, as will be shown hereafter, do not in the least obtain in the human subject in the form which has been hitherto attributed to them. Or the branches of the veins, which are always large, might easily be regarded as the locality, provided that the occurrences above mentioned be not regarded as extravasations. With regard to this question direct observation teaches us as fol- lows. In the capillaries and arteries of the spleen in mammalia no changes of the blood corpuscles exist ; so that the only question is, whether the blood corpuscles, which con- stantly occur in the spleen-pulp, and here un- dergo their metamorphoses, are situated in the commencements of the veins; or whether they occupy spaces newly formed by the ex- trusion of the blood. Much may be adduced in support of the first of these view's. Thus, it is scarcely possible to suppose that extra- vasations of blood in such extraordinary quan- tity constantly occur in the spleen ; then it may also be mentioned that pigmentary gra- nule-cells, such as are developed in the spleen from the blood, may also be found in blood- vessels exterior to the spleen, which seems to speak for their being situated within the ves- sels in the case of the spleen itself. I have VOL. IV. 785 myself formerly found scattered pigment-cells in human blood * which I can now only re- gard as granule-cells from the spleen. Ecker has also seen f in the splenic veins of the calf, cells containing blood corpuscles like those in the spleen. And, lastly, Meckel J has also found black pigment-cells in the blood of a woman whose spleen abounded in them. Finally, we may recollect, that in the amphibia the cells in question are certainly situated in the vessels. But, on the other side, it must not be forgotten that in the spleen of fishes metamorphoses of the extravasated blood take place, and that also portions of the extravasations enter the vessels, and that it is possible the pigment-cells in the blood may thus originate ; finally, that the masses of blood in the spleen-pulp are scarcely de- fined with the sharpness which they would possess even in veins with very delicate coats. In this state of things it is much better to abstain from giving a definite decision ; or if one be absolutely required, to attribute the metamorphoses of the blood in the spleen of mammals to both the localities mentioned. The changes of the blood globules in the spleen are not exactly similar in all circum- stances, either as regards the quantity of the cells thus changed, or the degree of metamor- phosis which they undergo. In fishes , all the blood globules, without exception, may be recognised as decomposing; yet the quantity of these varies, i. e. the number and size of the vesicles and masses previously described varies in a considerable degree in different in- dividuals and species, although no very de- finite laws have as yet been found out. Reptilia exhibited the following peculiarity. In newly-caught individuals, the cells con- taining blood corpuscles were very numerous and distinct ; but in those which had fasted one, two, or three days, they occurred in exceedingly small quantity ; while, finally, by a longer duration of the fasting (a week or more), they exhibited themselves in very great number, and of extraordinary distinct- ness ; while at the same time the spleen became large, dark red, and very rich in the normal blood corpuscles. When newts which bad fasted a week were fed, the cells previ- ously existing, and the unchanged blood cor- puscles, vanished, since they were changed into colored granule-cells, and only on the sixth day after the feeding did such cells re- appear ; but in three days afterwards almost all of these had again experienced a meta- morphosis into granule-cells. In mammalia I have, in a series of cases, seen the decom- positions of the blood corpuscles in as little as five, six, and more hours after eating, while immediately after the reception of food, or after a day’s fasting, I have failed to observe it. At my advice, Landis § instituted experi- * See also Fahrner, De Globulorum Sanguinis origine : Turici, 1845, p. 26. fig. 143. f Zeitschrift fur Rationelle Median, Band vi. S. 264. j Zeitschrift fiir Psychiatrie, 1847, S. 22. § Beitrage zur Lehre iiber die Verrichtungen der Milz : Zurich, 1847. 3 E 786 SPLEEN. ments concerning this on thirty rabbits, and obtained the following results. Of fifteen animals which were examined, two, five, and eight hours after eating, cells with unchanged blood globules were found in eleven ; in five they were in masses ; in six separate ; in four cases they did not occur at all. Fifteen other animals, which were killed twelve, twenty-four, and forty-eight hours after eating, showed in eleven cases no trace of the cells mentioned ; in two cases many were present, in two cases a few only. And, vice versa, golden yellow granule-cells ( metamorphoses of the cells with unchanged blood globules) occurred fourteen times in the latter animals ; ten times in great quantity, once in consider- able numbers, and three limes very sparingly, while in one instance only were they alto- gether wanting. In the fifteen animals first mentioned these were twice absent, five times sparingly present, twice in considerable num- bers, and six times in large quantity. The conclusion to be deduced from these facts is, that cells with unchanged blood globules only show themselves a short time after eating, and that the granule-cells which proceed from these are almost always present, although in greater number in animals which have fasted a considerable time. If any animal were examined at the proper time, one would be astonished at the uncommon quantity of de- composing blood globules; for in such a case the whole red part of the pulp consists (so to speak) of nothing but golden yellow or blackish corpuscles, which are the different metamorphoses of blood corpuscles already mentioned. Of the ultimate destiny of the blood cor- puscles so metamorphosed, thus much is certain, — that they are decomposed and dis- solved ; but, on the other hand, it is difficult to make out what is the destiny of the cells which usually enclose them We have already seen above that these cells occur in the splenic vein, the vena portre, and the inferior cava, and it is thence questionable whether all these cells may not possibly pass into the blood. It is difficult to give an answer to this. Thus much I consider to be made out : — that cells with unchanged blood globules, and yellow, brown, or blackish-yellow granule- cells, only' exceptionally and seldom pass into the blood of the splenic vein, or beyond ; since, in the first place, these cells are, upon the whole, rarely found in the blood ; while, secondly, their occurrence in the spleen is demonstrably very frequent. On the other hand, as to the colourless granule-cells wdtich finally arise from the cells containing blood corpuscles, it is not made out whether they remain in the spleen or enter the blood. Supposing the first of these to be the case, they may either abide a considerable time in the pulp, and then in a certain manner serve as parenchyma-cells, with which they have a great similarity, or they may experience a dissolution, and altogether disappear. In the second case, one may imagine that they are converted into lymph corpuscles, with wdiich they have, to some extent, a great similarity’ or that they undergo a solution in the blood of the portal vein and the rest of the circula- tion. I own that I cannot hazard a decision. It is certain that colourless granule-cells occur in the blood as well as in the spleen ; but it is also certain that they are much more frequent in the spleen, and that, as regards the blood of extravasation which un- dergoes metamorphosis, it may be definitely stated, that its products for the most part remain in the same place. So much for my experience of the decom- position of blood corpuscles in the spleen. Simultaneously with myself, Professor Ecker, of Basle, made similar observations, which likewise referred to a destruction of blood corpuscles, and which, soon after, lent an ad- ditional light to mine.* In contradiction to this, however, Gerlach has lately uttered the opinion that my observations allude to the formation of colored corpuscles within colorless ones; so that he explains the forms of cells which are found in the spleen in precisely the reverse way, and supposes that the cells with golden yellow granules are the younger, and those with unchanged blood corpuscles the elder ; that is, that they are those in which the blood corpuscles have completely developed themselves, and from which they are ready to be expelled or set free. So that if Gerlach be correct, the relation of the blood corpuscles to the spleen is precisely the reverse of that which I have stated, and they begin there in great quantities ; and it thus becomes important to inquire whose opinion is the correct one. But if my ex- periments upon the behaviour of the blood corpuscles in the spleen have no other con- sideration, this merit, at least, remains to them, that they accurately set forth the anatomical facts, and in this manner have already sufficed to refute such false theories as that of Gerlach. In point of fact, Gerlach is altogether wrong when he supposes that the golden yellow granules are changed into blood globules ; for this can in no way be proved, but very easily the contrary. He is equally in error in adducing, as a ground for this view, that blood corpuscles begin as cells ! in the embryonal liver, — a statement which is altogether incorrect. Anil when he finally adduces that since, according to Harless f, the blood corpuscles are destroyed by the alternating influence of nitrogen and carbonic acid, a second kind of solution of these in the spleen cannot be conceived ; it need only be remarked that this theory of Harless’s is not in the least proved as regards the living organism. So, also, Virchow J has expressed himself as partially against mine and Ecker’s account; since, though he does not at all doubt the dissolution of blood corpuscles, yet he altogether denies the origin of cells around * Loc. cit. f Ueber den Einfluss der Gase auf die Form der Blutkugelchen : Erlangen, 1846. J Archiv fiir pathologische Anatomie und klinische Medicin, Band i. SS. 452. 483. SPLEEN. heaps of blood corpuscles. This statement is only explicable by supposing that the Mam- malia and Reptilia, in whom this pheno- menon can be seen as plainly as could be wished, were not examined by Virchow. Besides, I do not maintain that the effused blood always forms cells containing blood corpuscles ; only I hold it as a fact established beyond all doubt, that this very frequently happens in the spleen as well as in extrava- sations in the lungs, lymphatic glands, brain, and thyroid body ; and while 1 believe that the formation of cells around these several effusions is not an equivalent fact, yet it is altogether certain that blood globules enclosed in cells undergo a more speedy dissolution than if they remain free. In conclusion, one word concerning the import of the changes of the blood corpuscles in the spleen. It may be asked, whether they constitute a normal and physiological, or a pathological appearance ? On the one side, very weighty grounds may be alleged for the normal character, especially their (so to speak) constant occurrence and innumerable quantity in such a number of animals living in their natural condition, as the amphibia and fishes were. Furthermore, the appa- rently complete health which existed in spite of the vast quantity of dissolving blood globules. Thirdly, in Reptilia, the cells con- taining blood corpuscles may be seen in blood- vessels which are in no way isolated from the general circulation. Fourthly, similar and constant changes of the blood repeated at short intervals are absent from other organs of birds, mammals, and reptiles ; and many other arguments might be adduced. But, in contrast to these facts, many others appear on a more careful contemplation, which may almost lead to the opinion that all the changes of the blood globules in the spleen are pos- sibly only pathological appearances. In fishes, dissolutions of the blood corpuscles occur not only in the spleen, but in an exactly similar way in other organs, namely in the kidneys, the liver, and the peritoneum. In the first of these organs their presence is constant; at least, in the examination of many examples of eel, pike, Coregonus muraena and muraenula, Salmo fario, Barbus fluviatilis, Cyprinus brama and carpio, and Tinea chrysitis, not only were they always present, but almost always as numerous as they were observed to be in the spleen. In the peritoneum and the liver they were sometimes scarce, sometimes frequent, but only in the carp and Tinea chrysitis were they constant ; in other fishes they were either altogether absent, or only occurred here and there, as in the trout. If to these facts be appended that in certain animals, — to wit, in cats, sheep, and others, — the changes of the blood corpuscles in the spleen are very seldom observed, one can scarcely resist the notion that the appearance is abnormal ; and this is much more the case when one con- siders that similar appearances which are known not to be physiological, constitute almost constant occurrences, and are asso- 787 dated with exactly parallel changes of blood globules. Of this, the small effusions of blood in the lungs, bronchial glands, and thyroid bodies of men, and those of the lymphatic glands and mesentery of pigs and rabbits, are instances. But this latter view is insusceptible of full explanation ; for although pathological effusions and metamorphoses of blood often constitute almost a constant oc- curence, yet, first, the quantity of blood globules which undergo dissolution in such effusions is in no comparison at all with that of the millions which are destroyed in the spleen ; and, secondly, it has yet to be shown that effusions of blood may not occur as a physiological phenomenon, as happens in the bursting of a Graafian follicle in the ovary, in menstruation, and in the separation of the placenta. And although all animals do not show in the spleen such a solution of the blood corpuscles as can be verified by the microscope, yet it is by no means proved therewith, that where this-takes place it de- pends on a pathological condition ; indeed, the blood corpuscles of different animals may undergo dissolution in different ways. At least thus much is certain, that in all animals, without exception, stagnations of blood occur in the spleen ; and I might add, almost of a certainty, in mammals, extravasations also. In these stagnations, the blood globules may dissolve themselves in the one case rapidly, in the other case slowly, and thus, according to the outer phenomenon, a difference will be produced. Such an occurrence may be 2^ly~ sio/ugical, since it is, at least in many animals, visibly constant and very extensive ; and it may have the greatest signification to the life of the organism. Therefore, so long as the pathological character of the phenomenon! s not proved of a certainty, I am disposed to hold fast by its physiological nature, and to consider the dissolution of the blood cor- puscles in the spleen as a normal fact. 6. Bloodvessels of the spleen. — The splenic artery ( arteria lienalis ) springs from the cteliac axis, and courses with man} windings between the layers of the gastro-colic liga- ment until it reaches the fundus of the stomach, where it enters the gastro-splenic ligament, after giving off some small twigs to the pancreas and the stomach. Arriving in the neighbourhood of the hilus lienalis, it divides into a superior and an inferior branch. The upper of the two, passing somewhat upwards, and giving backwards from two to six short arteries ( vasa brevia ) to the large extremity or pouch of the stomach, divides into from three to six branches, which, lying in a line one over another, extend to the hilus, into which they enter. The inferior branch is somewhat larger than the others ; it passes to the in- ferior and anterior part of the spleen, sup- plying it with three to six branches, which enter the hilus in the same manner as the others, and it ends finally as the gastro- epiploica sinistra. Thus, all the six to twelve branches which enter the spleen lie tolerably' 3 E 2 788 SPLEEN. in one line upon each other in the gastro- splenic omentum, and they are also connected to each other by fat and areolar tissue. The size of the splenic arteries is very consi- derable in proportion to that of the organ, and so also the thickness of their coats is worthy of notice. In the first of these re- spects, it is possible that only the thyroid gland exceeds the spleen ; the liver, which is so much larger than this organ, being sup- plied by an artery of scarcely larger size than the splenic, although we must not over- look the fact, that beside this the liver receives very much additional blood through the vena port®. In the mammalia generally, the splenic artery is proportionally smaller than in men ; this possibly depends only upon the more considerable contraction of the vessel at their death. Wintringham finds that the thickness of the arterial coats is greater than that of the aorta above the giving off' of the renal ar- teries, to which it bears the ratio of 1 to 0’762 ; he also states that they will sustain a pres- sure of 41 lbs. The serous covering of the spleen receives some unnamed small arteries : thus a twig is given to it from the left inferior phrenic artery, which courses in the phrenico-lienal ligament ; and, besides this, it receives branches from the first lumbar, from the left spermatic, and from the splenic itself. Addi- tionally to these, in some of the vertebrata, to wit in the calf, small twigs in great number leave the substance of the spleen, and after perforating the fibrous coat of the organ spread themselves out upon its surface. The sjilenic vein altogether corresponds in distribution to the splenic artery. So many primary arterial branches enter the hilus of the spleen, and just as many veins come out of it. These six to twelve veins unite into two branches, and receiving, the upper the venae breves from the stomach, and the lower the vena gastro-epiploiea sinistra, they constitute the trunk of the vein. In the spleen, and at their emergence from it, the veins lie anterior to the arteries, but then they place themselves posteriorly to them ; and it is behind the arteries that they unite to form the common trunk. This trunk receives a twig from the pancreas, from the lymphatics of the spleen, from the stomach, and, further, the vena coro- naria ventriculi ; it then passes away over the aorta to the under surface of the liver ; and, finally, with the vena mesenterica superior it constitutes the trunk of the vena portae. The splenic vein, like all the branches of the vena portae, has no valves, and is the largest branch which assists to form that trunk. Its width is very considerable: ac- cording to E.Home* and Giesker, the propor- tion to that of the arteries is as 5 to I ; and according to earlier authorities it is yet more. The proportionate size of the branches is still larger ; and, according to C. A. Schmidt, then- ratio in the spleen itself to that of the arteries * On the Structure and Uses of the Spleen, Phil. Trans, for 1808. which run with them is as 20 to 1. In con- trast to this, the thickness of their coats is very inconsiderable, and, according to Win- tringham, is to that of the arteries as 1 to 4-8 or 4’3, to that of the iliac vein as 1 to 3-5. On their entry into the spleen, both arterial and venous branches receive as a covering a process of that “ tunica propria” of the spleen which forms the vagina; vasorum, previously described. These are not alike in all animals : thus, for instance, they differ in man from those ex- hibited by the higher brute mammalia — a fact which explains the various descriptions given by different authors. In man, the sheaths of the vessels form complete coats around them. A section made in the centre of the hilus, and continued through the spleen, exhibits them very distinctly as projections or processes of the tunica propria, and also allows their further circumstances to be seen. It is thus shown that arteries, veins, and nerves are thickly enclosed in these sheaths ; hut in such wise that they are easily separated and isolated, especially in old, or macerated, or boiled spleens. The arteries and nerves allow of this more easily than the veins, which latter have a closer connection to these sheaths. It is further seen that not only are the trunks of entering and emerging vessels thus covered, but that their finer ramifications receive a similar clothing. The thickness of these sheaths is in the human subject by no means inconsiderable. As Giesker correctly states, they are at first exactly the thickness of the tunica propria, and retain the same thickness for a considerable distance, that is, as long as they clothe the main trunks of the vessels. On the branches which proceed laterally from these trunks, and on their fur- ther extent, the sheaths become naturally finer, and gradually increase this fineness as the vessels become more minute, until finally, becoming very delicate, they lose themselves in the pulp of the spleen in the manner previously mentioned. The thickness of a sheath is always less than that of the coat of [ the artery which it incloses, and greater than that of the vein ; yet this does not hold good of vessels in all parts of their extent, since on the finest branches the sheaths are pro- portionally somewhat stronger than on the larger ones. As to the relations of the sheaths to the rest of the spleen substance, it must especially be considered that they do not lie free in the parenchyma of the organ, but are connected with the general trabecular network by means of balks which are given off' from them: but these balks are not so J numerous as different anatomists appear to think ; so that we are scarcely entitled to con- sider with Giesker, that the whole trabecular network is formed out of this connection. In other Mammalia, as in the horse, ass, ox, pig, sheep, &c., the course of these sheaths differs in some respects from that seen in man. In the three latter animals, which in this respect are best known to me, no SPLEEN. sheaths at all are found on the smaller veins, and on the larger they are chiefly found on that side on which the arteries and nerves which accompany them lie. Only the two primary trunks of the veins which proceed from the spleen have for a very short dis- tance a complete sheath, while all the arte- ries, even the finest, possess one ; a con- dition of which more will be said hereafter. The minute structure of the sheaths of the vessels in man altogether correspond with that of the partitions ; and this holds good of animals generally. But I have not been able to detect unstriped muscular fibre in the sheaths in all those cases in which I have found it in the trabeculae. In oxen this is especially the case; while, on the con- trary, in pigs, &c., they are very plainly present. Great difficulties oppose the inquiry con- cerning the distribution of the vessels in the spleen itself : since, lstly, injection or in- flation of the vessels gives little result on account of the delicacy of the organ ; and, 2dly, great difficulties are connected with the microscopic examination of the organ. What will be now adduced concerning it is espe- cially the result of the latter method of in- quiry, which, combined with fine preparations by the knife, has seemed to me to be the most fertile in results. When the main branches of the splenic artery have entered into the spleen they lie in their sheaths, each in company with a vein, to which they are posterior and infe- rior : they are in tolerably loose connection with the sheath, and not unfrequently they take a serpentine course. In their further distribution they do not behave as arteries generally do, which continually give off smaller branches, but they divide immediately into a quantity of different large and long branches in the manner of a shrub ; of these the larger branches go to the anterior, the smaller to the posterior, margin of the organ. Beside this, it is especially to be remarked of the arteries of the spleen, that their different branches form no anastomoses. Assolant tied a branch of the splenic artery in a living dog, and then allowed the spleen to return into the cavity of the belly. The dog died thirty hours after : much inflammation and exsudation of a bloody serous fluid was found in the belly, and the spleen was quite healthy ; only the part cut off from the circulation of the blood was gangrenous, and, as it were, separated from the sound part by a line of demarcation. In contrast to this, Heusinger tied all the branches of the splenic artery, one only excepted ; upon dissection, the whole spleen was found to be mortified, excepting the part in which the artery not deligated ramified. Also injections in an artery always return solely by the corresponding branch of vein ; and they only fill that region of the spleen in which the branch ramifies, never passing over into any other. I am unable from mv own experience to pass any judg- ment upon these data, and will therefore not 789 impugn them ; but I may be allowed to doubt whether the capillaries of the pulp are com- pletely separated from each other, and am more inclined to believe that, in consequence of the anatomical circumstances of the pulp, such a separation^ must be considered as im- possible ; since in the spleen we have before us, not a gland with special lobes separated from each other, but a parenchyma every- where united. The above results of deli- gation and injection by no means necessarily imply an isolated course of the capillaries, and are fully explained by the supposition that the arteries possess no anastomoses. When the arteries have divided into small vessels of 1 to 2-100ths of a line, they come into contact with the Malpighian corpuscles in the mode already described ; while they are also connected to these by them sheaths. According to Giesker, their final terminations are coronal or pencil-shaped, radiating so as to surround the Malpighian corpuscles, and altogether enclose them ; then arriving at the highest point of the vesicle, they return upon themselves in the shape of a loop, course back again as veins, and there meet together, beneath the point whence the artery radiated, to form a vein, which enters the same sheath from which the artery emerged. At this point the sheath divides into three to four fibrous threads, which pass over on the spleen corpuscles to the threads arising nearest to them, and unite with these. If we compare with this description of the minute anatomy of the spleen that which is considered most admissible by J. Muller, the next author after Giesker, we shall find very considerable contradictions. J. Muller finds that the smallest branches of arteries partly continue on the side of the corpuscles with- out giving off branches to them, partly per- forate either a portion or the whole of the corpuscle, without in any instance leaving any branches of the artery in its interior ; that these fine arterial branches pass through the middle of the corpuscles, then con- tinue on their coats, and then quit them altogether ; and that if an artery in the corpuscle divides into many branches — which never happens on the surface, but alwa}*s in the thickness of its coats — these branches leave it again, in order to ramify minutely in the surrounding red pulpy substance of the spleen, into which part especially all the fine pencil-shaped ramifications of the arteries pass. The commencements of the veins spring from these branches ; they are tolerably large, anastomose frequently with each other, and scarcely have a special coat as yet. If a little piece of the pulp of the spleen be care- fully examined, it will be seen that it is as if cribriform, and constitutes as it were a net- work of red partitions, the diameters of which are larger than the interspaces and canals existing between them. It is these venous canals which give the cellular appear- ance seen in inflation of the veins of the pulp, and which, injected, form structures resembling the corpora cavernosa of the 790 SPLEEN. penis. Special cells or cavities do not exist. So far J. MLiller. If we now ask ourselves the reason of these important differences be- tween these two authors cited, one of whom affirms the continuation of the tufts in the pulp, and a connection of Malpighian cor- puscles with arteries and venous interstices only ; while the other denies all this, we shall find it not very difficult to give an answer. Giesker, in his description, limited himself to the appearances met with in the human subject, while J. Miiller made the pig and the ox the basis of his delineation. This circumstance will at least partially explain the want of corre- spondence in the two descriptions ; for 1 find that between the spleen of man and that of the animals mentioned considerable differences exist. In man, at least generally, the arteries to- gether with the veins pass deeply into the substance of the spleen, lying in the same sheath with them, and exactly following their course. According to Giesker, the two classes of vessels accompany each other even to their final ramifications ; but this is not correct. In every spleen instances occur, which are easily seen, where small veins and arteries lie very close to each other ; and Giesker has evidently allowed himself to regard these par- ticular instances as the rule, and has ex- tended it as a description to the smallest branches of vessels. But if an arterial and venous primary branch be successively fol- lowed to their minutest ramifications, it will be seen that, sooner or later, every artery and vein, without exception, separate from each other, and follow their special path. It is not at all unusual to find this even with arteries from to 1 line in diameter, but it is always the case with those of from 1 -10th of a line. In such an instance the artery, setting out alone, does not perforate the sheath in which it hitherto lay, but takes with it a distinct yet often inseparable covering of the same ; so that from this point forwards a special and se- parate venous and arterial sheath exist. And in man the Malpighian corpuscles lie only on these isolated arteries ; a state which Mal- pighi and Muller had already described in Mammalia. As regards the other circumstances of the arteries, I have found them exactly as Miiller describes them in the lower animals. After the smaller branches of the arteries are connected with the Malpighian corpuscles, they enter into the red spleen substance, and immediately' upon this each small trunk spreads out in the shape of a tuft into a large number of yet finer arte- ries {Jig. 526, d.) ; and these tufts or pencils of arteries, lying in great numbers close to each other, give to the terminations of the arterial trunks a very beautiful appearance, which may be best compared to the broad crown of a ( pollard ) tree. These separate tufts, dividing and diminishing in size yet more, terminate by an immediate transition into the true capillaries ; which, in a more and most minute form of 3 to 5-1000ths of a line, constitute a close and beautiful network in the separate portions of the pulp, and in those parts of it which sur- round the Malpighian corpuscles ; although they do not form a special vascular covering for the same. Many authors seem to deny the existence of capillaries in the spleen : thus Engel * has lately altogether denied them; but this is quite erroneous. They may easily be seen in the pulp of the human spleen, by the aid of the microscope, both empty and filled with blood, and exhibit themselves as in no way different from the capillaries of other organs ; and the finest of them have a dia- meter of only 3-1000thsof a line. J. Muller is also in error when he describes the arteries as coursing through the coats of the Mal- pighian corpuscle, since they always pass on its exterior. Finally, Giesker is wrong in describing the arterial pencils as spreading themselves out on the Malpighian corpuscle, and here becoming continuous with the veins ; even in man it is not difficult to discover that the pencils only begin beyond the corpuscles, that they lie in the pulp, and that it is here they first break up into capillaries. Giesker at least partially agrees with this statement when he says f that the pulp con- sists of nothing but the minutest arteries and veins united by fibrous tissue. The sheaths of the vessels above described are just as much more delicate as are the vessels themselves, and they are finally lost as distinct coats on the capillaries ; here they form delicate fibrous membranes which connect the capillaries to- gether, and under this form they pass through the whole of the pulp. As to the veins, I must first, with Giesker, express myself in the most decided manner against all the more ancient and modern ana- tomists who suppose and describe venous spaces ( sinus venosi) in the human spleen. I have bestowed the greatest attention to the dilated commencements of the veins in ques- tion, anil it was only my own researches that led me to renounce the opinion that these dilatations really exist ; indeed I have never been able to discover anything special or ex- traordinary about these veins. Firstly, as to the larger veins, which are as yet accom- panied by tlie arteries, there is nothing very remarkable about them, with the exception of their considerable size, which has been already mentioned. They all have a membrane which is continuous with that of the smaller veins, and is least separable on that side with which the artery is in contact ; this membrane is only distinguishable from the sheath of the vessels by its greater delicacy, and in com- pany with this sheath it gradually diminishes its thickness. Orifices of the smaller veins, constituting the so-called stigmata Malpighi, are present in very small numbers in the larger veins ; while, on the other hand, they are somewhat more frequent in the smaller of the vessels in question. When the veins * Zeitsclirift der Gesellschaft der Aerzte in Wien, 1847. f Loc. cit. S. 166. SPLEEN. leave the arteries and pursue their way alone, they vary in some respects from this descrip- tion, although not so considerably as might be imagined from the delineations which have been given of them. In the first place, the character of the branchings is peculiar, since from hence onwards, and so much the more frequently the smaller the veins become, branches are given oft' from the veins on all sides at very nearly right angles, and the open mouths of these ramifications are seen from within as numerous round or oval orifices lying very closely to each other. In the second place, the membranes of these veins gradually become thinner and thinner, and at the same time are blended with the similarly attenuated sheaths, so that both constitute only one delicate membrane, which is never- theless everywhere demonstrable even in the smallest vessels which can be isolated, and which everywhere exhibits itself without any interruption as a perfectly continuous mem- brane. Dilatations or pouchings can no- where be seen, either in the course of the isolated veins or in their smallest branches ; only it must be added, that the narrowing of their calibre occurs much more slowly than in the arteries. As to the beginnings of the veins, and their connection with the ca- pillaries, I have not been able to detect any- thing more than what one sees elsewhere ; namely, that by a constant simplification and attenuation of their structure, the veins finally pass into capillaries. Here also no traces of dilatations are visible, of whatever kind these dilatations might be imagined to be ; and there is just as little appearance of any other pecu- liarity. As regards the brute mammalia, many of them certainly correspond in a very considerable de- gree with man, in respect of the condition of these vessels ; but my researches do not ex- tend sufficiently to enable me to express myself decisively on this point. While, on the other hand, some, as the horse, ass, ox, pig, and sheep, exhibit essential differences. In the latter animal, which I have examined the most carefully, the following deviations are pre- sent. The arteries differ little from those of man, only they separate earlier from the veins to pursue their isolated course. In most other respects they behave precisely as J. Muller has described them, and as I have also spoken of them in man ; only I cannot corroborate the statement of Muller, that the sheaths of the smaller arteries are equal in strength to those of the greater. The rami- fications which reach the Malpighian cor- puscles measure from 1 to 1 i-lOOths ofaline in diameter; they then course in the pulp, form very beautiful tufts, and finally capillaries, of which the smallest measure from 3 to 4- lOOOths of a line. But in contrast to this, the veins exhibit very essential differences. In the first place, a special membrane and sheath are only found in the largest venous trunks, and even here they only extend a short dis- tance around the circumference of the vessel ; while more deeply in the spleen they only lie 791 upon the side where the artery and nerve are attached to the vein. In all the smaller veins which are no longer accompanied by arteries, there is no trace of these two membranes to be seen ; and not only is this the case, but the mode in which the precise limit of the venous canal is indicated is also very extra- ordinary. The vein appears to be formed in the first instance by the strong anastomosing trabeculae, and soon afterwards it seems com- posed simply of delicate fibres and red sub- stance deposited between them, a structure which continues even into the large venous trunks. They thus distinguish themselves at the first glance as excavations in the paren- chyma of the spleen, which are devoid of walls. Nevertheless, by a more careful ex- amination of the red limits of these veins, one may verify their smooth and shining appear- ances, a circumstance which is significant of the existence of a delicate membranous cover- ing ; and, in point of fact, microscopic inves- tigation proves the existence of an epithe- Ffg. 534. Epithelial cells from the Splenic vein of Man and other Mammalia. Magnified 350 diameters. lium, which every where clothes this surface, and consists of fusiform or more spherical cells, of a to I - 1 00th ofaline in diameter, with roundish or elongated nuclei of 3 to 5- lOOOths of a line in size {fig. 534.). This epi- thelium altogether corresponds with that which covers the part of the veins possessing a visible membrane ; but in the vessels of which I am speaking, it is placed in part imme- diately on the trabeculae, in part upon a deli- cate fibrous membrane limiting that part of the pulp which bounds the veins. In con- sequence of what has been said, the greater number of the splenic veins of the ox must be likened in respect of their structure to the spaces in the corpora cavernosa penis, and to the sinuses of the dura mater ; since, in- stead of the venous membranes elsewhere present, they possess only the “ tunica mtitna ” in the shape of a delicate epithelium. So that one may speak of them as “ venous sinuses,' and the more correctly, it it be considered that these veins, almost devoid ot walls, possess a colossal width, and are every- where rendered quite cribriform by larger and smaller veins opening into their interior ; which smaller veins may themselves be traced by their great width for a considerable dis- tance. How these smaller veins are con- nected with the very distinct capillary net- 3 e 4 792 SPLEEN. work of the pulp, I have not been able to find out ; and I do not believe that either injec- tion or inflation of the vein, or a microscopic examination, will ever give any definite con- clusion hereto. For these vessels, often pos- sessing but a few little trabeculae for their coats, are of such a delicate texture, that they tear by theslightest mechanical force, while by the microscope the}' cannot be distinguished from the surrounding constituents of the pulp. Yet thus much one may see, that the veins gradually become very small, — so small, that it is quite impossible to talk of their commen- cing as dilated spaces. For my own part, I am convinced that a similar communication obtains between the veins and capillaries of oxen as of men ; and that the only possible difference is, that the veins here possess only an epithelium, and must therefore be con- nected with the capillaries in a somewhat dif- ferent way. I will yet further add, that in microscopic examination of the pulp of ani- tiials, skeins of epithelium are not unfre- quently found, consisting of roundish cells, as it were, fused together : these can only come from the small venous trunks. The following may be noticed concerning the microscropic structure of the splenic vessels : • — The arteries everywhere possess their three usual coats. The inner consists, first, of an Fig. 535. Epithelial cells from the human Splenic artery, a, shorter cells ; h, somewhat longer cells. epithelium of spindle-shaped cells, which easily come off in skeins or separately (fig. 535, a, b) ; and, secondly, of an elastic mem- brane of homogeneous composition, wrinkled in the longitudinal direction (fig. 528, e.), and with or without openings : which openings although very small, are visible even in the arteries of the tufts. The middle tunic is very thick, and gives rise to the considerable thickness of the wall of the vessel ; it con- tains very little else but unstriped muscular fibres. In the larger and largest arteries, nets of elastic fibre and elastic membrane (gefenslirle membranen of Henle) are also present, while they exist without exception on the vessels which pass to the Malpighian corpuscles, and on those which form the pencils or tufts. The adventitious for cellu- lar) coat is altogether absent from the smaller vessels in the interior of the spleen, and is here represented by the sheath ; but it exists in the larger vessels, and presents white fibrous tissue and meshes of elastic fibres. The capillaries (fig. 53G.) have’a simple, struc- tureless membrane, with nuclei lying on its Fig. 53G. Capillary from the Spleen of the Pig. Magnified 350 diameters. inner surface. The veins have been already described as they exist in brute mammalia : in man they possess — 1 . An epithelium as above described ; 2. A membrane of elastic longi- tudinal fibres ; 3. Transverse unstriped mus- cular fibres, in a single or double layer, which are present in the trunk of the splenic vein and all its primary branches in the interior of the spleen, but are absent from the smaller and smallest veins ; 4. White fibrous tissue, with elastic fibres which take a longitudinal direction. The smallest veins possess only white fibrous tissue with elastic fibres, and an epithelium. So much has been already said above con- cerning the blood of the splenic vessels and of the spleen, that I will here only append some special observations made upon animals. In a dog whose spleen abounded in the dissolv- ing blood globules, the blood of the splenic vein distinguished itself by a very great quan- tity of colourless blood corpuscles, almost all of which contained numerous nuclei, and often had a deceptive resemblance to pus globules. In the blood of the liver were found a great number of altogether different blood Fig. 537. Blood corpuscles from the liver and Splenic vein of a Dog, ivith yellow crystals of a substance resembling Hcematine. globules'(_yfg. 537.). These were swollen out and almost colorless, but contained from 1 to 5 thinner or thicker small rods of a dark yellow colour; part of these possessed the same length as the blood globules, part were shorter. These small rods were unchanged in water, but in acetic acid they seemed to disappear. In a second dog i found the same cells with small yellow rods in the blood of the splenic vein, while they could not be detected in any other part of the body. With them I found at the same time numer- ous colourless blood globules with manifold nuclei. In the fresh-water perch, the blood SPLEEN. 793 of the splenic vein of many individuals con- tained numerous golden yellow cells with diminished blood globules. In the same blood, and in the splenic pulp, there also occurred, either sparingly or in uncommon quantity, rod-shaped crystalline corpuscles, of a yellow colour, and a length of 4 to 6-1000ths of a line : at the first glance they seemed to be lying altogether free, and they were dissolved by potash {Jig. 538, b). On the application of water a membrane was upraised from these Fig. 538. Similar llood corpuscles from the Spleen and Splenic vein of the fresh-water Perch, a, crystals and nuclei seen on treating colourless nucleated blood corpuscles with water ; b, crystals apparently free. small rods, and near them a nucleus came into view (Jig. 538, a). On more accurate in- quiry, it plainly appeared that these small rods lie in decolorized blood globules, and in unchanged blood globules the gradual form- ation of one, or even two, of these may be followed. In Barbus Jluviatilis, the spleen pulp contains an enormous quantity of really free crystals ; these are of a violet and reddish colour, and of a nail or spindle-shaped form ; and on the application of acetic acid, they are completely dissolved, leaving some colour behind. Crystals such as these also occurred sparingly in the kidneys, the liver, and the blood of the heart. In this animal, as well as in Cyprinus brama, the blood contained yellow granule-cells, like those which occur in the spleen and kidneys. All the rod- shaped yellow corpuscles just named (of which the first, indeed, are nothing but crystals) must in any case consist of a substance allied to the haematin of the blood ; and possibly they consist of the substance which Virchow has lately named haematoidin, with which they correspond in some respects. Their occur- rence in the spleen is physiologically inter- esting, and so also is their formation within the blood corpuscles, while at the same time it affords a very plain indication of the rela- tion of haematin to them. 7. Lymphatics . — The views of authors con- cerning the lymphatics of the spleen are very' contradictory, since one class have the prece- dent of Haller for altogether denying their existence in the human spleen, while others have stated their existence in abundance, and have constituted the spleen, in a certain mea- sure, a large lymphatic ganglion. This differ- ence mainly depends hereon, — that the one class have specially examined the human spleen, while others have chiefly drawn their conclusions from that of the lower animals, considerable differences in respect of these vessels existing in different creatures. In man, the lymphatics of the spleen are, at any rate, in utterly in" considerable quantity, being rather less nu" merous than in other glandular organs, as the liver and kidneys, and not at all so numerous as in the lymphatic glands. They are divi- sible into superficial and deep. The former course, in sparing numbers, between the two coats of the spleen, and form in this situation delicate trunks, which anastomose with each other ; but, excepting in perfectly healthy spleens, and in the neighbourhood of the hilus , they can scarcely be recognised. The latter lie in sparing numbers in the hilus, and in the sheaths of the vessels, where they accompany the arteries, although they cannot be traced so far as there. Both sets of these vessels pass to the gastro-splenic omentum, to enter the small lymphatic glands placed there ; and finally they collect to a trunk which opens into the thoracic duct, at about the eleventh or twelfth dorsal vertebra. All these lymph- atic vessels can only be thus seen in the quite fresh and undeteriorated spleens of executed criminals or subjects killed by accidents, al- though they may often be recognised in parti- cular parts of the healthy spleen after natural death, especially if the vessels be tied and the spleen soaked in water. But, on the other hand, in diseased spleens it is very rare to see even a trace of them, unless a preparation be made of a small gland in the gastro-splenic ligament, in which case small entering and emerging trunks may be recognised. In the lower animals, or at least in many of them, the lymphatics seem to be more nume- rous. Moreschi distended the lymphatics of the spleen in fishes (in whom they possess no valves) from the trunk, and he says that the in- jected spleen appeared to consist almost solely of a network of absorbents. But in another place he freely states that the spleen consists, so to speak, of nothing but vessels. In a Testudo mydas, Tiedemann and Gmelin saw all the absorbents of the small intestine going to the spleen, in which, by interlacing with arteries and veins, they formed a network. From this network large branches, like the emer- gent vessels of the lymphatic glands, took their course towards the thoracic duct. Al- most all the older writers recognised the rich- ness of the spleen in lymphatics, which later examiners have but confirmed. But it will be well to set forth one fact which, in my opinion, is not sufficiently estimated, namely that even here absorbents are only sparingly jtresent in the interior of the spleen ; at least I have found this to be the case in the pig, ox, sheep, &c. Here the superficial lymphatics are, as is well known, very numerous, and this fact seems to me to correspond with the circumstance that in these animals the serous and fibrous coats are only loosely connected to each other, and contain many vessels in the loose areolar tissue between them. But, on the other hand, if the vessels in the hilus be examined, only a few scattered trunks can be seen, a condition which stands in extraordinary contrast with the very nu- merous lymphatics of the coats. Thus, for 791 SPLEEN. instance, in the hilus of a large calf I found only four trunks of lymphatics, which toge- ther possessed a diameter of only 176-1000ths of a line ; while the interior of the spleen is also poor in lymphatics, for, so far as I have seen, the numerous plexuses of lymphatic trunks in the coats of the spleen have no rela- tion with the interior of the organ, but at least the greater number of them belong solely to the snbserous areolar tissue. As to the distribution of the lymphatics in the spleen, it may easily be seen, by observ- ations on oxen, that they only follow the course of the arteries, lying with these in- side the sheaths; while the veins, which take a solitary course, and (as was before mentioned) possess no sheath, are also devoid of these companions. I have not seen the commencement of the lymphatics, yet I can state for a certainty, that they have nothing to do with the Malpighian corpuscles, since these corpuscles are completely closed, as was before mentioned. And, I will add, in support of this my view, that the small arte- ries which pass to the Malpighian corpuscles are no longer accompanied by lymphatic vessels ; at least microscopic examination detects no trace of such vessels within their sheaths. Just as little does the pulp possess any lymphatics ; for if these, like the nerves (see below), pass from the sheaths of the arteries into the pulp, they would in such a case be visible. And from what has been said, I conclude that the lymphatic vessels of the interior of the spleen belong wholly and solely to the sheaths of the arteries, and not in the least to the pulp or the Malpighian corpuscles ; and thus that here they play pre- cisely the same rather subordinate part which they do in the liver, where they pertain to the capsule of Glisson, and not to the glandu- lar substance ; or as in the kidneys, in the interior of which they only accompany the bloodvessels. Concerning the structure of the lymphatic vessels, I can only state thus much ; that in the calf they possess, at least in their main trunks, three membranes : — 1. An epithelium similar to that of the arte- ries ; 2. A circular fibrous membrane, com- posed of two or three layers of very distinct unstriped muscular fibres ; 3. An outer mem- brane of white fibrous tissue. Valves occur in the deep as well as in the superficial lymph- atics. 8. Nerves. — The nerves of the spleen arise from the splenic plexus, and accompany the splenic artery as two or three interlacing trunks, and divide in such wise at the giving off of its branches, that each artery receives one, or very frequently two nerves, which accompany it, and here and there anastomose with each other. The thickness of the primary nervous trunks varies very much in different creatures. Thus in the sheep, and especially in the ox, they are of really a colossal size, and taken all together, their diameter equals that of the empty and contracted splenic arteries ; while in man and the pig they are no way remarkable in size, and are many times smaller than the arteries. These differences, which led the earlier authors to speak of the splenic nerves in similarly different expressions, were at first altogether inexplicable to me, since I could not understand why the spleen of one animal should possess so much larger nerves than another. On a more careful examin- ation, the microscope gave a very simple and unforeseen explanation. The uncommon size of the splenic nerves of Ruminantia depends solely on this, — that the white fibrous tissue of these nerves is disproportionally developed in the shape of the so-called “ fibres of Remak,” while it is much less prominent in the same nerves of other animals. A com- parison of the splenic nerves of the pig and calf has taught me that if we limit our inquiry to the number of primitive nerve fibres, scarce any difference exists between the two sets of nerves. But, on the other hand, the primi- tive nerve fibres of the pig lie very closely together, so that they cannot be numbered without considerable trouble ; while as an example of their condition in the calf, I will adduce the following: — The trunks of the nerves entering the hilus were seven in number, with a diameter of ‘37, *2, '048, -6, '48, ‘48, •6 (line) ; and they contained respectively only 28, 7, 6, 9, 13, 9, 22 primitive nerve fibres. In the lower animals, the nerves may be followed with the knife for a considerable distance into the spleen, much further than in man ; and with the help of the microscope, I have very frequently followed them even on the arteries which go to the Malpighian corpuscles. I have been just as little able as Remak to find any ganglia on the arteries in the interior of the spleen. Concerning their mode of termi- nation, I am only able to say thus much ; that the nerves also pass into the pulp, and may even be easily seen on the pencils of arteries, and finally that they disappear as very small branches of not greater size than the smallest capillaries ; but I am unable to decide whether they terminate by means of Fig. 539. A very small nerve from the Spleen of the Calf with- out any visible primitive nerve fires, and apparently consisting only of neurilemma (or fbres of Remak). Magnified 350 diameters. SPLEEN. 795 loops or with free extremities. In the calf, the thickness of these smallest nerves on arteries of a line in diameter (where it is not uncommon to find two such trunks) is 24 to 28-1000ths of a line ; on the pencils of arteries 48 to 56-10, OOOths ; on the smallest ar- teries and capillaries 3 to 4-1000ths. Their structure was so far peculiar, that in the calf the finest nerves {fig. 539.) exhibited no trace of nerve fibres, even when treated with soda and acetic acid, but they seemed to consist wholly and solely of the fibres of Remak. Nevertheless, in branches of 12 to 28-1000ths of aline, I have often very plainly seen a single Fig. 540. A somewhat larger nerve, in which may be seen a single dark nerve fibre : also from the Calf. Mag- nified 350 diameters. nerve tubule of 20 to 28-10, OOOths of a line {fig. 540.), with dark margins, in the midst of the fibres of Remak. From these facts it may be concluded that the finest nerve tubes in the spleen of the calf are devoid of the dark bor- ders, just as they are in the organ of smell according to Todd and Bowman ; or as in the Pacinian corpuscles, the cornea, &c. ; but we are scarcely able to conclude therefrom that they possess the same constitution in the adult animal. I will here permit myself to Fig. 541. Two primitive nerve fibres given off from the trunk of the splenic nerve of the Calf, about an inch before its entry into the Spleen. Magnified 350 diameters. add an interesting microscopic observation concerning the splenic nerves of the calf. A division of the primitive nerve fibres takes place in them {fig. 541.), similar to that which Henle and myself found in the Pacinian cor- puscles, Muller, Briicke, and R. Wagner in the muscles, and Savi and R. Wagner in the electrical organ of the torpedo. But what is altogether new in the minute anatomy of nerve is, that these divisions do not take place at the terminations of the primitive nerve fibres, but in their trunks. I detected them in the large trunks which accompany the splenic artery previously to its entering the hilus ; and, indeed, in considerable numbers, so that I often counted three or four such divisions in one preparation. They always took place by the division of a primitive nerve fibre at an acute angle into two parts, and never gave rise to more fibres. These divisions often repeated themselves on the same fibre, so that in one instance three, and in another case even four, fibres were given off by the successive divisions of a single primitive fibre : this happened in the smaller branches in the interior ; but, so far as I could remark, it did not occur in the smallest branches of nerves, although, from the difficulty of examining the finer nerves, I cannot say that such divisions were absolutely wanting here. The significa- tion of these facts seems to be very important, both in an anatomical and physiological point of view, but this is not the place to give a more detailed statement. But thus much will I remark ; that by means of such a dis- tribution of the nerves, a small nerve may be rendered subservient to a larger organ ; and, in addition, an harmonious activity of the whole organ may be facilitated ; while, finally, in respect to sensation, it may possibly ex- plain the want of an exact local sensibility. In concluding this treatise on the anatomy of the spleen, I will allow myself briefly to propound somewhat concerning the physio- logical and pathological properties of the organ. The spleen is developed at the end of the second or the beginning of the third month, in the fetal mesogastrium at the fundus of the stomach. It originates from a blastema which is developed independently in this situation, and neither proceeds from the intestine, like that of the liver, nor from the pancreas, as Arnold has maintained ; since, although in the ruminants it is placed on this gland, yet in the dog, according to Bischoff, it is not. It is at first a small, white, often slightly ta- bulated corpuscle, which gradually reddens, and soon becomes as rich in vessels and blood as it is in the adult.* The elements of the fetal spleen are originally quite uniform cells ; at a later period part of these are transformed into fibres and vessels, while part become persistent as the parenchyma-cells. It is only subsequently that the Malpighian corpuscles are developed, yet I have found them, without exception, both in man and animals, at the end of the fetal life. Ac- cording to Heusinger, the proportion of the 796 SPLEEN. spleen to the whole body is, in an embryo of ten weeks old, as 1 to 3000 ; in the eighth month it is, according to Huschke, as 1 to 720 ; while at birth, he states it to be as 1 to 357 ; in the adult as 1 to 235 to 400 ; and in old age as 1 to 600 to 800. From these data it will be seen, that the proportionate weight of the spleen to that of the whole body in- creases very rapidly in the embryo, and is almost as great at the period of birth as in the adult ; from which it sufficiently follows, that the spleen is an organ, the activity of which extends from the end of the foetal period through the whole life, and reaches its highest point in middle age. As regards the function of the spleen, of the innumerable theories and hypotheses re- specting it, only a very few deserve a nearer consideration ; namely, only those which place the spleen in intimate relation with the life of the blood. In point of fact, almost all the facts which with greater or less certainty we know concerning the spleen, and, above all, the ana- tomical ones, point to such a relation. Hew- son had already stated, that when an organ receives more blood than it requires for its own nutrition, we may conclude therefrom that that blood undergoes a change in it, or a secretory process takes place ; and this ex- pression will not apply to any organ in the body better than to the spleen, which must be considered as relatively better supplied with blood than any other organ. Therefore since all pathological, anatomical, and physiological facts prove a relation of the spleen to the blood, we may securely assume, that a change of the blood takes place in the spleen. The only difficulty is to know what change. Firstly, the blood may either suffer a change in its transition from the arteries to the veins ; or, secondly, the separation of a particular lymph from the blood may take place in this organ. It is well known that the latter view was first maintained by Hewson *, who at the same time announced that the lymph generated in the spleen serves to form blood corpuscles ; and since then, Tiedemann and Gmelin have specially supported the same view. But the grounds adduced for this theory seem to me to be insufficient. At one time, the great quan- tity of lymphatics in the spleen was brought to prove that a special lymph was developed here. But that part of the spleen on which special stress is laid, namely, the interior or parenchyma, is quite poor in lymphatic vessels; and its surface, even in the lower animals, scarce contains more of such vessels than other organs ; to wit, the peritoneum covering the liver, the pleura covering the lungs, &c. Therefore the formation of a special lymph by the spleen can as little be assumed as in the case of the lungs and liver. Se- condly, the red colour of the spleen-lymph, and its greater coagulability, have been ad- duced as proofs of a peculiarity, and of a blood-forming import. But it may be de- manded, are these properties constant, and on * Opus posthumum, sive rubrarum sanguinis par- tieularum thymi et lienis descriptio, 1786. what do they depend ? As to the first ques- tion, it is certain that a red colour of the spleen-lymph is, on the whole an exception, as Seiler and Ficinus * formerly stated. In rabbits, cats, or dogs, I have never found such a colour, and have also always found the chyle of the thoracic duct of only different shades of white. But I will not deny that in calves and sheep a reddish spleen-lymph is often found, and I will add that this is frequently the case in the horse. But this is sometimes the case in other organs, as, for instance, in the liver and in the lacteals, where Tiedemann and Gmelin in some cases also found a reddish and very easily coagulable fluid ; and it is im- portant to observe, that the reddish colour and easy coagulability in these cases depend simply on blood which is mixed with the lymph. Thus, if the reddish spleen-lymph of a calf be examined, a quantity of fully de- veloped blood corpuscles are found in it, which are altogether identical with those in the blood, f Now since it cannot be as- sumed that real coloured blood globules are formed in the lymphatic vessels of the spleen, and since, in point of fact, all trace of such a developement of blood globules is absent, it will only follow from the facts adduced, that in the cases of reddish spleen-lymph a mixture of real blood and lymph has taken place. This mixture may be the result of normal anas- tomoses between lymph and bloodvessels, or may owe its origin to a rupture of both these vessels. I believe the latter to be the case, and am simply of the opinion that it is not at all to be wondered at. For in Tiedemann’s cases the animals were either killed by a blow on the head, or died during convulsions ; and it is not surprising that during such a death- struggle an organ so richly supplied with blood as the spleen should make an abnormal path for that fluid, or that a similar thing should happen when the vena porta has been tied. It is well enough known, how easily the lymphatics of the spleen are filled by an injection into the bloodvessels. The reddish colour and easy coagulability of the spleen- lymph in particular cases therefore proves nothing at all, except that, on account of its great vascularity, blood is more easily extra- vasated in the spleen than elsewhere, and enters the lymphatic vessels. Thirdly and lastly, Tiedemann and Gmelin adduce the above-mentioned course of the lymphatics in the tortoise as a powerful proof of their view ; but Rudolphi J found exactly the contrary, since in two large sea-tortoises not a single lymphatic of the intestine passed to the spleen, but they all went directly to the thoracic duct. In consequence of what has been said — which I might also corroborate by many other facts could I go more into detail — it is im- possible to imagine the development of a special lymph in the spleen ; and hence the * See Giesker, S. 265. f See also Nasse, (Wagner’s Handworterbuch der Pliysiologie, Band ii. S. 370.) J Pliysiologie, Band ii. Pleft 2. S. 156. SPLEEN. 797 theory which ascribes to the spleen a relation to the lymphatic system, and considers it as in a certain manner a large lymphatic gland, is utterly devoid of meaning. In this manner there remains as a last resource the view, that changes occur in the blood itself con- tained in the spleen. But what is the na- ture of these changes ? Are blood corpuscles possibly formed in the spleen, as has been already so often supposed ? Certainly not ; for in the most rigorous examination of the blood in the spleen and the larger splenic vessels, just as in the spleen-lymph, no trace whatever of the formation of blood globules can be detected, much less in blood which is exactly reversed, and is exhibiting, as I might say, at every step the plainest and most lively indications of a dissolution and decomposition. Let us recall to mind the details already given of the condition of the blood globules in the spleen. Upon the facts there men- tioned, in the year 1847 * I founded the con- jecture that the blood corpuscles undergo solution in the spleen, and that their colouring matter is employed in preparing the colouring matter of the bile ; a conjecture which seems to me preferable to all those which have hitherto been offered concerning the function of the spleen. If the fact be made out that new blood globules are continually arising from the cells of the chyle, it is just as certain that the blood globules must also slowly dis- appear in order to maLe room for those newly arising. And if it be considered that nobody has yet seen the least trace of a solution of blood globules in any other organ, and that, on the contrary, 1 have found in the spleen a healthy organ, in which, in all four classes of vertebrate animals, blood corpuscles are almost constantly undergoing decomposition, even in uncommon quantities, it will, I think, be conceded to me that I have some grounds for setting forth the hypothesis here given. It is, indeed, as yet not altogether settled whether the changes of the blood seen by me are normal or abnormal ; but, as was previously remarked, so long as their patho- logical nature is not proved with certainty, I must continue to regard them as physiological and pertaining to healthy life. But this is not saying that they occur in all creatures in the method described above. It is highly possible that blood globules undergo disso- lution in the spleen without previously form- ing the cells containing blood corpuscles : an opinion which is corroborated by the blood globules described above as occurring in the blood of the splenic vein of the dog and fresh-water perch : these contained crystals of haematine or some kindred substance, and were evidently near their destruction. In- deed, it is even possible that such a direct mode of dissolution may be the rule in some animals, perhaps even in many. And although I have regarded the spleen as an organ in which the blood corpuscles undergo disso- lution, yet I have not maintained therewith * Loc. cit. S. 135. that it is in all animals the only organ in which any thing of this kind occurs : it would therefore in no way militate against my theory if it should ever turn out that in the kidneys of fishes, the vessels of which are arranged so peculiarly, a constant and physio- logical solution of blood globules obtained. The following circumstances also speak for my hypothesis. That in no other way can any reasonable account be given of the changes of the blood in the spleen. Further- more, that it elucidates the relation of the spleen to the portal system of veins ; since ac- cording to it, the dissolved blood corpuscles are subservient to the formation of the bile, the colouring matter of which is so nearly allied to that of the blood. Finally, that, as will be more fully stated below, the patho- logical facts are proportionally in unison with it. On all these grounds I am therefore in- clined to defend the hypothesis first set forth by me of a destruction of the blood globules in the spleen ; and the more so, that J. Be- dard has lately maintained, that the blood of the splenic vein is always poorer in blood cor- puscles than that of the other veins. He has stated this in a memoir which was laid be- fore the Academie des Sciences in Paris on the 17th January, 1848, and published in the “ Archives generates de Medicine” of Oc- tober to December, 1848. Since J. Bedard’s results are an important support to my' hypo- thesis, I have permitted myself to communi- cate here the most important of them. Be- dard has analysed the blood from the lower branch of the splenic vein, and that front the jugular vein, in fourteen dogs and two horses. In most of the instances of the analysis, (1.) the water, (2.) the blood corpuscles and fibrine, and (3.) the albumen and salts, were separated from each other ; and only in the horses were the blood corpuscles and fibrine obtained separately. A deficiency of the blood globules and fibrine was always present in the splenic vein, which diminution out of a 1000 parts of blood, amounted to the fol- lowing quantities in the sixteen cases. 1654 15-94 8-51 37-11 19-67 13-06 19-43 20-80 14-91 12-82 10-88 9-40 13-92 16-06 13-60 14-78 On an average of the sixteen cases, the de- ficiency amounted to 16’OS parts. As regards the albumen, on the contrary, there was a constant increase of this constituent in all the sixteen cases, in an average of 13‘02 parts. Finally, in the two analyses in which the quantity of fibrine w as certified, there was the extraordinary increase in its quantity in the blood of the splenic vein of 0‘3 and 0'5 parts. Beclard deduces the same conclusion from these facts which I have drawn from my micro- scopical examinations ; namely', that the blood corpuscles normally undergo dissolution in the spleen ; and 1 regard this conclusion as neither more nor less correctly deduced than 798 SPLEEN. mine, for it is dear that the results of his ana- lyses may solely depend upon this fact, that in the animals he examined, the changes which I have verified in the blood globules of the spleen, were going on in an energetic manner. If these visible changes of the blood globules, — which certainly occur in a most exquisite manner in the horse and dog, — if they be nor- mal appearances, then is the diminution in the quantity of the blood globules, which Be- dard found on analysis, also a normal phe- nomenon ; but if not, then he only examined a blood partially deprived of its globules by stagnation and effusion. The results of che- mical analysis would then only be secure, if it were at the same time shown, that there were no visible changes of the blood globules in the spleens of the animals examined. Until this takes place, Bedard’s conclusion will remain, like mine, hypothetical ; although this is in no way diminishing the merit of his ob- servations, since I hold my own hypothesis as one which I am perfectly justified in pro- pounding in the present state of our know- ledge. But even if we suppose that the blood corpuscles are destroyed in the spleen, it is nevertheless a question how this dissolution is super-induced, and at what time it comes to pass. As regards the first of these points, in my writing previously mentioned I ex- pressed the opinion, that the spleen is a con- tractile organ, and may, by virtue of its con- tractility, be able to dilate and contract itself, ■ — to fill itself with blood, and again to expel the blood from it. In the state of filling itself with blood, a stagnation of blood occurs in the smaller vessels, perhaps even an extravasa- tion ; and in this stagnant blood, the blood globules undergo destruction, since they slowly dissolve themselves, either free or in- closed in cells. This view I still regard as cor- rect. For, firstly, it is a matter of fact that the spleen does enlarge and diminish its size, and certainly under vital circumstances which are altogether normal. Very many of the older observers have accepted this fact ; as Lieu- tand, Haller, Stuckeley, Rush, Clarke, Hodg- kin, Home, and Dobson. This is shown by an examination of the splenic region in the living human subject (Piorry). So also it is shown by vivisection of animals, in whom I have myself seen (and especially in the dog) a very distict diminution and rounding of its outer surface. Finally, Landis *, by weighing the spleen, has recognised a distinct increase and diminution of weight. He examined at different times thirty rabbits, and finds that the average weight of the organ in five obser- vations was : 12 hours after eating, 0-768 grammes.f 5 „ „ -588 8 „ „ ’548 24 „ „ -526 48 „ „ -510 2 „ „ ‘444 ,, Now although it may be freely conceded that * I.oc. cit. t The “ gramme ” is 15J grains Troy English. (Transl.) an organ like the spleen is subject to so many variations in respect of size as to render thirty observations much too small a number to afford any very definite information con- cerning its increase or decrease of size, it must, nevertheless, be considered, that Landis has examined the proportion of the spleen to the whole body, and to many other organs, as the stomach, liver, and kidneys, and that from this means he derived a confirmation of what the estimate of its absolute weight had previously taught ; so that his observations must be regarded as a meritorious contri- bution to our knowledge respecting the changes of volume which the spleen expe- riences. We now ask, secondly, how these changes come to pass ? Beclard states that the spleen enlarges and becomes filled with blood in consequence of the splenic vein being com- pressed by a muscular force; but the nature of this he has not stated, nor can I regard his view as correct. I believe myself to have propounded a better theory when I stated, that the spleen becomes turgesceut in conse- quence of the relaxation of the muscular fibres which exist in its balks, coats, and vessel-sheaths ; or in animals from whom these are absent, through a relaxation of the muscular fibres of the vessels themselves. A constriction of the splenic vein cannot be supposed to obtain, since the muscular fibres which it contains are but very little de- veloped, and no other compressing force is present ; while, on the contrary, we know that in all animals the splenic artery is uncom- monly muscular, and that the partitions of the spleen themselves contain distinct muscular fibres. It is these muscles and no others which, according to my researches, produce the distension of the spleen ; but not through their contracting together, but by their re- laxation, which brings with it a distension of the vessels with blood, and a slower circu- lation of this fluid. The diminution in the size of the spleen occurs simply through the contraction of the muscular parts just named. Precisely in the same manner the corpora cavernosa of the penis become filled with blood by a relaxation of the muscles situated in their fibrous partitions ; and become poorer in blood, and smaller in size, when the mus- cles again contract themselves. Of course, both here and in the spleen, the nerves play an important part in the process ; probably in consequence of antagonistic relations be- tween them and other parts of the nervous system, which at present cannot be accu- rately indicated. Thirdly, and finally, it may be asked, whether the blood corpuscles simply dissolve because the blood of the spleen be- comes stagnant at certain times, or whether special influences are necessary to this effect ? — whether the parenchyma of the spleen or the Malpighian corpuscles may not secrete a juice, a “ succus lienalis,” of which the earlier authors speak, which exerts a solvent in- fluence on the blood corpuscles ? Asa kind of vague answer to this question, I have ex- amined the parenchyma with respect to its SPLEEN. 799 reaction, and have found that without ex- ception it has an energetic acid reaction. This appeared to me very extraordinary, and the more so when I thought of the great quan- tity of blood which the organ contains; and I was already captivated by the conjecture that this acid reaction might be of great import- ance. But I found that litmus paper was .just as much reddened by the liver and kidneys of the calf and rabbit ; and, further, that the muscular substance of the heart and the muscles of the trunk have the same effect. So that this acid reaction appears to be a general phenomenon, which is probably due to the fact, that the acids lately found by Liebig in muscle (lactic and inosic acids) also occur elsewhere. At any rate since there is as yet no exact chemical analysis of the spleen, I cannot express myself con- cerning the import of this vigorously acid re- action of its parenchyma ; although it is very conceivable, that the acid reaction does not depend on the same causes in all organs. As regards the time at which the blood globules experience their dissolution in the spleen, nothing definite can at present be said ; but my theory appears at least to pre- suppose, that this process especially comes to pass some time after the reception of nutri- ment, since I have found the spleen of the greatest size in animals at about the time of five to twelve hours after eating, the same time at which the visible changes of the blood globules were most marked. The cause of this phenomenon seems to be, that the vo- lume of the blood is increased after each time of taking food, and especially that a great num- ber of new cells enter from the chyle. And if an equal weight is to remain in the organism, then, on the other hand, just as many elements of the blood must be dissolved, as there have new ones entered into it ; and this is ex- actly what happens in the spleen. Besides, I am not anxious to maintain that the spleen may not become distended, and blood glo- bules undergo dissolution, at other times than those just mentioned ; probably the con- ditions of tiie liver have also a great influence upon the events in the spleen, so that in hypersemia of the liver, the spleen becomes also distended ; and so likewise the nervous sys- tem may be interested therein. Beclard, who has also found many variations in the blood globules contained in the blood of the splenic vein, is unable to assign any definite cause for these varieties, and only remarks, that in the case of a blood rich in blood globules, the amount of these lost in the spleen was greater than in the opposite case. So that it must be left to the future to bring to light the more special relations of the dissolution of the blood globules in the spleen. I have hitherto said nothing concerning the function of the Malpighian corpuscles of the spleen. I do not regard their function as at all a peculiar one, since ( 1 .), in many animals, as fishes and naked amphibia, these corpuscles are ab- sent ; 2. their constituents exactly correspond with those of the parenchyma of the spleen. I believe that the parenchyma-cells and the cells of the Malpighian corpuscles play exactly the same part, although I am just as little able as my predecessors to say with certainty what this is. If they are not subservient to the formation of a special fluid which takes a part in the solution of the blood corpuscles, I should be almost inclined to ascribe to the parenchyma- cells the mechanical use of form- ing in the first place a soft parenchyma in which the minute vessels can extend at their pleasure ; and nextly, that they, as well as the elements of the Malpighian corpuscles, are simply expressions of the fact, that the spleen, as a highly vascular organ, is everywhere permeated by a fluid which is very rich in plastic matters. At the same time, it may be imagined that all these cells elaborate the fluid in which they are soaked, and after a certain kind of assimilation, again part with it, and through the blood and lymph vessels transmit it to the general circulation. The swelling up of the Malpighian corpuscles after the use of food is quite consonant with this notion. But whether this fluid is of a pe- culiar nature, and of different properties from that of other organs, we can only know from future chemical researches ; and then only can it be determined, whether or no we are to ascribe to it a special signification. If the spleen be the only or even the chief organ in which blood globules undergo their dissolution, in either case the part which they enact in the organism is by no means the subordinate one which many have hitherto considered it ; but one which is very full of import. And the results afforded by vivisec- tions and by pathology are by no means so contradictory to this expression as they are generally maintained to be. It is true that the spleen of animals may be excised without causing their death, a fact which I have my- self repeatedly witnessed ; it is also certain, that men can live without spleens, or with spleens completely atrophied, or rendered functionally useless by degeneration ; nay, in many cases, may live without any disturb- ance at all, — a circumstance which is also true of animals. But what does this prove ? Nothing at all ; for if the spleen fails, then indeed other organs undertake its functions, and discharge them vicariously for it. Pro- bably in these cases the blood globules un- dergo dissolution in the general mass of the blood, or possibly in the liver. But if this be so, the spleen is surely not therefore devoid of import or function. With equal correctness might we say, that one kidney is superfluous, because in certain cases an hypertrophied kidney enacts the part of both ; or might re- gard kidneys generally as devoid of import, because certain rare instances of misdevelope- ment are narrated, in which the skin or the thoracic glands have undertaken the excre- tion of the urinary constituents. If the spleen is not the only organ in which blood cor- puscles undergo dissolution, it is possible that these are destroyed in some small quantity in the capillaries of all the organs of the body. 600 SPLEEN. Many observers, as Lecanu and Letellier, and more recently J. Beclard, have found a dimi- nution in the quantity of blood corpuscles in the venous blood generally, although others have denied this. If this be the case, it con- firms such a supposition, and would effectually explain the results of extirpation. In any case thus much is certain, that they afford no grounds for regarding the spleen as devoid of signification. Finally, we may remark in ad- dition, that not unfrequently extirpations of the spleen give rise to considerable disturb- ances, and especially of the biliary secretion ; a fact which very well corresponds with my supposition that the colouring matter of the bile arises from the haematin set free in the spleen. If this theory of the function of the spleen which I have set forth, which Ecker has adopted, and which J. Beclard has now con- firmed, be correct, it will be able to explain the diseased conditions of the spleen and their operation on the organism. But this is at present impossible, since these conditions are much too little known to allow us to say any- thing even approximatively correct and secure concerning their origin and import. There- fore, instead of entering upon a discursive detail of possibilities resting upon an alto- gether hypothetical basis, it seems to me much more suitable, simply to indicate the points to which future observers might pro- perly direct their special attention. It is known that the enlargements of the spleen, which constitute the most serious diseases of the organ, have a special coincidence with complaints in which either a dissolution, or some other abnormal condition of the blood is present. This is the case in typhus, typhoid cholera, pya-mia, putrid exanthemata (erysi- pelas, scarlatina, measles), dyscrasia of drunk- ards, ague, scurvy, purpura, chlorosis, acute rheumatism, acute tuberculosis, &c. May not the enlargement of the spleen possibly have a share in the production of these diseases, without being so entirely secondary as most pathologists have hitherto assumed ? Is it not conceivable, that in a spleen which is enlarged and distended with blood, a destruction and dissolution of the blood globules is going on on too large a scale, so that the normal composition of the blood becomes seriously prejudiced thereby ? In such a case the blood would be poorer in blood globules, but its plasma would be rich in colouring matter, and possibly at first in fibrine, as J. Beclard found it to be in his analysis. May not chlorosis or scurvy, in which a considerable diminution of the blood corpuscles has been shown to exist, possibly depend in part on the dispropor- tionate activity of an enlarged spleen ? In consequence of such a too considerable de- struction of blood globules in other cases, further changes of the blood may be induced, which may then end as an overcharging of the fluid with colouring matter ; to wit, with the colouring matter of the bile ; or as a pyaemia or the so-called white blood. On the other hand, is it not possible, that in cases of the temporary diminution, or inflammation, or de- generation, or atrophy of the spleen, other organs may undertake its functions ? — as, for instance, the liver, which, indeed, is usually hypertrophied in such cases ; or the general mass of blood, a state which must again give rise to peculiar phenomena ? Thus, in re- spect of its pathology there is much which might yet be observed, if I did not consider it more suitable to conclude with the remark, that in order to the building of a larger super- structure upon the anatomical and physi- ological basis here given, and in aiming at anything respecting the pathology of the organ, a deliberate, careful inquiry is above all things necessary, an inquiry in which chemical analysis, microscopical research, experiment, and pathological experience, will have to go hand in hand. For if I have perhaps been able to elucidate the spleen in many respects more correctly than my predecessors, yet this ac- count is very far from a final termination of our knowledge, and must be regarded as nothing more than a foundation-stone for an altogether new superstructure. Morbid Anatomy. — Variations in number and form have already been alluded to. The absence of the organ is usually or always accompanied by that of other and neighbour- ing viscera. On account of the obscurity which has hitherto attached to the anatomy of the organ, its diseased conditions are little understood ; and it is obvious, that until morbid conditions of the spleen are examined and classified with reference to the appearances of their several anatomical constituents, there will be little to be said under the head of morbid anatomy, besides enumerating the most prominent de- viations of its bulk, colour, and consistence. Enlargement of the spleen is, perhaps, the most common of all the outward deviations! We have already seen that, within certain and very wide limits, the size of the spleen may vary, and that these wide variations are of constant occurrence even in the healthy sub- ject, being intimately associated with its func- tion and that of the organ. It is, therefore, only when such enlargement becomes exces- sive, or is associated with an alteration of texture, or occurs in the course of some of those diseases which it is known usually to accompany, that we are justified in regarding it as essentially morbid. The enlargement of the organ, to all out- ward appearance, depends mainly on the in- creased mass of the contained blood, and is hence sometimes called hypersemia ; and the most obvious distinction of this enlargement is into two kinds : — one in which the conges- tion is produced mechanically ; the other, in which the determination of blood to the organ can only be accounted for on the supposition of non-mechanical causes. The former of the two classes would include the swollen spleens which occur in obstructions of the portal vein, or of the vena cava, as happens in some diseases of the liver and heart respectively. I Todd